Repository: golang/tools
Branch: master
Commit: 02548f745018
Files: 2761
Total size: 13.6 MB

Directory structure:
gitextract_5udc9x7r/

├── .gitattributes
├── .gitignore
├── .prettierrc
├── CONTRIBUTING.md
├── LICENSE
├── PATENTS
├── README.md
├── benchmark/
│   └── parse/
│       ├── parse.go
│       └── parse_test.go
├── blog/
│   ├── atom/
│   │   └── atom.go
│   ├── blog.go
│   └── blog_test.go
├── cmd/
│   ├── benchcmp/
│   │   ├── benchcmp.go
│   │   ├── benchcmp_test.go
│   │   ├── compare.go
│   │   ├── compare_test.go
│   │   └── doc.go
│   ├── bisect/
│   │   ├── go120.go
│   │   ├── main.go
│   │   ├── main_test.go
│   │   └── testdata/
│   │       ├── README.md
│   │       ├── basic.txt
│   │       ├── count2.txt
│   │       ├── double.txt
│   │       ├── max1.txt
│   │       ├── max2.txt
│   │       ├── maxset.txt
│   │       ├── maxset1.txt
│   │       ├── maxset4.txt
│   │       ├── negate.txt
│   │       ├── rand.txt
│   │       ├── rand1.txt
│   │       └── rand2.txt
│   ├── bundle/
│   │   ├── .gitignore
│   │   ├── main.go
│   │   ├── main_test.go
│   │   └── testdata/
│   │       ├── out.golden
│   │       └── src/
│   │           ├── domain.name/
│   │           │   └── importdecl/
│   │           │       └── p.go
│   │           └── initial/
│   │               ├── a.go
│   │               ├── b.go
│   │               └── c.go
│   ├── callgraph/
│   │   ├── main.go
│   │   ├── main_test.go
│   │   └── testdata/
│   │       └── src/
│   │           └── pkg/
│   │               ├── pkg.go
│   │               └── pkg_test.go
│   ├── compilebench/
│   │   └── main.go
│   ├── deadcode/
│   │   ├── deadcode.go
│   │   ├── deadcode_test.go
│   │   ├── doc.go
│   │   └── testdata/
│   │       ├── basic.txtar
│   │       ├── filterflag.txtar
│   │       ├── generated.txtar
│   │       ├── issue65915.txtar
│   │       ├── issue67915.txt
│   │       ├── issue73652.txtar
│   │       ├── jsonflag.txtar
│   │       ├── lineflag.txtar
│   │       ├── marker.txtar
│   │       ├── testflag.txtar
│   │       └── whylive.txtar
│   ├── digraph/
│   │   ├── digraph.go
│   │   ├── digraph_test.go
│   │   └── doc.go
│   ├── eg/
│   │   └── eg.go
│   ├── file2fuzz/
│   │   ├── main.go
│   │   └── main_test.go
│   ├── fiximports/
│   │   ├── main.go
│   │   ├── main_test.go
│   │   └── testdata/
│   │       └── src/
│   │           ├── fruit.io/
│   │           │   ├── banana/
│   │           │   │   └── banana.go
│   │           │   ├── orange/
│   │           │   │   └── orange.go
│   │           │   └── pear/
│   │           │       └── pear.go
│   │           ├── new.com/
│   │           │   └── one/
│   │           │       └── one.go
│   │           ├── old.com/
│   │           │   ├── bad/
│   │           │   │   └── bad.go
│   │           │   └── one/
│   │           │       └── one.go
│   │           └── titanic.biz/
│   │               ├── bar/
│   │               │   └── bar.go
│   │               └── foo/
│   │                   └── foo.go
│   ├── go-contrib-init/
│   │   ├── contrib.go
│   │   └── contrib_test.go
│   ├── godex/
│   │   ├── doc.go
│   │   ├── gc.go
│   │   ├── gccgo.go
│   │   ├── godex.go
│   │   ├── isAlias18.go
│   │   ├── isAlias19.go
│   │   ├── print.go
│   │   ├── source.go
│   │   └── writetype.go
│   ├── goimports/
│   │   ├── doc.go
│   │   ├── goimports.go
│   │   ├── goimports_gc.go
│   │   └── goimports_not_gc.go
│   ├── gomvpkg/
│   │   └── main.go
│   ├── gonew/
│   │   ├── main.go
│   │   ├── main_test.go
│   │   └── testdata/
│   │       └── quote.txt
│   ├── gotype/
│   │   ├── gotype.go
│   │   ├── sizesFor18.go
│   │   └── sizesFor19.go
│   ├── goyacc/
│   │   ├── doc.go
│   │   ├── testdata/
│   │   │   └── expr/
│   │   │       ├── README
│   │   │       ├── expr.y
│   │   │       └── main.go
│   │   └── yacc.go
│   ├── html2article/
│   │   └── conv.go
│   ├── present/
│   │   ├── dir.go
│   │   ├── doc.go
│   │   ├── main.go
│   │   ├── play.go
│   │   ├── static/
│   │   │   ├── article.css
│   │   │   ├── dir.css
│   │   │   ├── dir.js
│   │   │   ├── jquery-ui.js
│   │   │   ├── jquery.js
│   │   │   ├── notes.css
│   │   │   ├── notes.js
│   │   │   ├── play.js
│   │   │   ├── playground.js
│   │   │   ├── slides.js
│   │   │   └── styles.css
│   │   └── templates/
│   │       ├── action.tmpl
│   │       ├── article.tmpl
│   │       ├── dir.tmpl
│   │       └── slides.tmpl
│   ├── present2md/
│   │   └── main.go
│   ├── signature-fuzzer/
│   │   ├── README.md
│   │   ├── fuzz-driver/
│   │   │   ├── driver.go
│   │   │   └── drv_test.go
│   │   ├── fuzz-runner/
│   │   │   ├── rnr_test.go
│   │   │   ├── runner.go
│   │   │   └── testdata/
│   │   │       └── himom.go
│   │   └── internal/
│   │       └── fuzz-generator/
│   │           ├── arrayparm.go
│   │           ├── gen_test.go
│   │           ├── generator.go
│   │           ├── mapparm.go
│   │           ├── numparm.go
│   │           ├── parm.go
│   │           ├── pointerparm.go
│   │           ├── stringparm.go
│   │           ├── structparm.go
│   │           ├── typedefparm.go
│   │           └── wraprand.go
│   ├── splitdwarf/
│   │   ├── internal/
│   │   │   └── macho/
│   │   │       ├── fat.go
│   │   │       ├── file.go
│   │   │       ├── file_test.go
│   │   │       ├── macho.go
│   │   │       ├── reloctype.go
│   │   │       ├── reloctype_string.go
│   │   │       └── testdata/
│   │   │           ├── clang-386-darwin-exec-with-rpath
│   │   │           ├── clang-386-darwin.obj
│   │   │           ├── clang-amd64-darwin-exec-with-rpath
│   │   │           ├── clang-amd64-darwin.obj
│   │   │           ├── fat-gcc-386-amd64-darwin-exec
│   │   │           ├── gcc-386-darwin-exec
│   │   │           ├── gcc-amd64-darwin-exec
│   │   │           ├── gcc-amd64-darwin-exec-debug
│   │   │           └── hello.c
│   │   └── splitdwarf.go
│   ├── ssadump/
│   │   └── main.go
│   ├── stress/
│   │   └── stress.go
│   ├── stringer/
│   │   ├── endtoend_test.go
│   │   ├── golden_test.go
│   │   ├── multifile_test.go
│   │   ├── stringer.go
│   │   ├── testdata/
│   │   │   ├── cgo.go
│   │   │   ├── conv.go
│   │   │   ├── conv2.go
│   │   │   ├── day.go
│   │   │   ├── gap.go
│   │   │   ├── int8overflow.go
│   │   │   ├── num.go
│   │   │   ├── number.go
│   │   │   ├── prime.go
│   │   │   ├── prime2.go
│   │   │   ├── tag_main.go
│   │   │   ├── tag_tag.go
│   │   │   ├── unum.go
│   │   │   ├── unum2.go
│   │   │   └── vary_day.go
│   │   └── util_test.go
│   └── toolstash/
│       ├── buildall
│       ├── cmp.go
│       └── main.go
├── codereview.cfg
├── container/
│   └── intsets/
│       ├── export_test.go
│       ├── sparse.go
│       └── sparse_test.go
├── copyright/
│   ├── copyright.go
│   └── copyright_test.go
├── cover/
│   ├── profile.go
│   └── profile_test.go
├── go/
│   ├── analysis/
│   │   ├── analysis.go
│   │   ├── analysistest/
│   │   │   ├── analysistest.go
│   │   │   └── analysistest_test.go
│   │   ├── checker/
│   │   │   ├── checker.go
│   │   │   ├── checker_test.go
│   │   │   ├── example_test.go
│   │   │   └── print.go
│   │   ├── diagnostic.go
│   │   ├── doc/
│   │   │   └── suggested_fixes.md
│   │   ├── doc.go
│   │   ├── internal/
│   │   │   ├── analysisflags/
│   │   │   │   ├── flags.go
│   │   │   │   ├── flags_test.go
│   │   │   │   └── help.go
│   │   │   ├── checker/
│   │   │   │   ├── checker.go
│   │   │   │   ├── checker_test.go
│   │   │   │   ├── fix_test.go
│   │   │   │   ├── start_test.go
│   │   │   │   └── testdata/
│   │   │   │       ├── conflict.txt
│   │   │   │       ├── diff.txt
│   │   │   │       ├── fixes.txt
│   │   │   │       ├── generated.txt
│   │   │   │       ├── importdup.txt
│   │   │   │       ├── importdup2.txt
│   │   │   │       ├── json.txt
│   │   │   │       ├── noend.txt
│   │   │   │       ├── overlap.txt
│   │   │   │       └── plain.txt
│   │   │   ├── internal.go
│   │   │   └── versiontest/
│   │   │       └── version_test.go
│   │   ├── multichecker/
│   │   │   ├── multichecker.go
│   │   │   └── multichecker_test.go
│   │   ├── passes/
│   │   │   ├── README
│   │   │   ├── appends/
│   │   │   │   ├── appends.go
│   │   │   │   ├── appends_test.go
│   │   │   │   ├── doc.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── b/
│   │   │   │               └── b.go
│   │   │   ├── asmdecl/
│   │   │   │   ├── asmdecl.go
│   │   │   │   ├── asmdecl_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── asm.go
│   │   │   │               ├── asm1.s
│   │   │   │               ├── asm10.s
│   │   │   │               ├── asm11.s
│   │   │   │               ├── asm2.s
│   │   │   │               ├── asm3.s
│   │   │   │               ├── asm4.s
│   │   │   │               ├── asm5.s
│   │   │   │               ├── asm6.s
│   │   │   │               ├── asm7.s
│   │   │   │               ├── asm8.s
│   │   │   │               └── asm9.s
│   │   │   ├── assign/
│   │   │   │   ├── assign.go
│   │   │   │   ├── assign_test.go
│   │   │   │   ├── doc.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               ├── typeparams.go
│   │   │   │               └── typeparams.go.golden
│   │   │   ├── atomic/
│   │   │   │   ├── atomic.go
│   │   │   │   ├── atomic_test.go
│   │   │   │   ├── doc.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── atomicalign/
│   │   │   │   ├── atomicalign.go
│   │   │   │   ├── atomicalign_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── stub.go
│   │   │   │           └── b/
│   │   │   │               ├── b.go
│   │   │   │               └── stub.go
│   │   │   ├── bools/
│   │   │   │   ├── bools.go
│   │   │   │   ├── bools_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── buildssa/
│   │   │   │   ├── buildssa.go
│   │   │   │   ├── buildssa_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           └── c/
│   │   │   │               └── c.go
│   │   │   ├── buildtag/
│   │   │   │   ├── buildtag.go
│   │   │   │   ├── buildtag_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── buildtag.go
│   │   │   │           │   ├── buildtag2.go
│   │   │   │           │   ├── buildtag3.go
│   │   │   │           │   ├── buildtag4.go
│   │   │   │           │   ├── buildtag5.go
│   │   │   │           │   ├── buildtag6.s
│   │   │   │           │   ├── buildtag7.s
│   │   │   │           │   └── buildtag8.s
│   │   │   │           └── b/
│   │   │   │               ├── vers.go
│   │   │   │               ├── vers1.go
│   │   │   │               ├── vers2.go
│   │   │   │               ├── vers3.go
│   │   │   │               ├── vers4.go
│   │   │   │               ├── vers5.go
│   │   │   │               └── vers6.go
│   │   │   ├── cgocall/
│   │   │   │   ├── cgocall.go
│   │   │   │   ├── cgocall_go120.go
│   │   │   │   ├── cgocall_go121.go
│   │   │   │   ├── cgocall_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── cgo.go
│   │   │   │           │   └── cgo3.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           ├── c/
│   │   │   │           │   └── c.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── composite/
│   │   │   │   ├── composite.go
│   │   │   │   ├── composite_test.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   ├── a.go.golden
│   │   │   │   │       │   ├── a_fuzz_test.go
│   │   │   │   │       │   └── a_fuzz_test.go.golden
│   │   │   │   │       └── typeparams/
│   │   │   │   │           ├── lib/
│   │   │   │   │           │   └── lib.go
│   │   │   │   │           ├── typeparams.go
│   │   │   │   │           └── typeparams.go.golden
│   │   │   │   └── whitelist.go
│   │   │   ├── copylock/
│   │   │   │   ├── copylock.go
│   │   │   │   ├── copylock_test.go
│   │   │   │   ├── main.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── copylock.go
│   │   │   │           │   ├── copylock_func.go
│   │   │   │           │   ├── copylock_range.go
│   │   │   │           │   ├── issue61678.go
│   │   │   │           │   └── newexpr_go126.go
│   │   │   │           ├── forstmt/
│   │   │   │           │   ├── go21.txtar
│   │   │   │           │   └── go22.txtar
│   │   │   │           ├── issue67787/
│   │   │   │           │   └── issue67787.go
│   │   │   │           ├── typeparams/
│   │   │   │           │   └── typeparams.go
│   │   │   │           └── unfortunate/
│   │   │   │               ├── local_go123.go
│   │   │   │               └── local_go124.go
│   │   │   ├── ctrlflow/
│   │   │   │   ├── ctrlflow.go
│   │   │   │   ├── ctrlflow_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── lib/
│   │   │   │           │   └── lib.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── deepequalerrors/
│   │   │   │   ├── deepequalerrors.go
│   │   │   │   ├── deepequalerrors_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── defers/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── defers/
│   │   │   │   │       └── main.go
│   │   │   │   ├── defers.go
│   │   │   │   ├── defers_test.go
│   │   │   │   ├── doc.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── directive/
│   │   │   │   ├── directive.go
│   │   │   │   ├── directive_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── badspace.go
│   │   │   │               ├── issue66046.go
│   │   │   │               ├── misplaced.go
│   │   │   │               ├── misplaced.s
│   │   │   │               ├── misplaced_test.go
│   │   │   │               └── p.go
│   │   │   ├── errorsas/
│   │   │   │   ├── errorsas.go
│   │   │   │   ├── errorsas_test.go
│   │   │   │   ├── main.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── fieldalignment/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── fieldalignment/
│   │   │   │   │       └── main.go
│   │   │   │   ├── fieldalignment.go
│   │   │   │   ├── fieldalignment_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               ├── a.go.golden
│   │   │   │               ├── a_386.go
│   │   │   │               ├── a_386.go.golden
│   │   │   │               ├── a_amd64.go
│   │   │   │               └── a_amd64.go.golden
│   │   │   ├── findcall/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── findcall/
│   │   │   │   │       └── main.go
│   │   │   │   ├── findcall.go
│   │   │   │   ├── findcall_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── framepointer/
│   │   │   │   ├── framepointer.go
│   │   │   │   ├── framepointer_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── asm.go
│   │   │   │               ├── asm_amd64.s
│   │   │   │               ├── asm_arm64.s
│   │   │   │               ├── asm_darwin_amd64.s
│   │   │   │               ├── asm_linux_amd64.s
│   │   │   │               ├── asm_windows_amd64.s
│   │   │   │               └── buildtag_amd64.s
│   │   │   ├── gofix/
│   │   │   │   ├── doc.go
│   │   │   │   ├── gofix.go
│   │   │   │   ├── gofix_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── hostport/
│   │   │   │   ├── hostport.go
│   │   │   │   ├── hostport_test.go
│   │   │   │   ├── main.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── httpmux/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── httpmux/
│   │   │   │   │       └── main.go
│   │   │   │   ├── httpmux.go
│   │   │   │   ├── httpmux_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── httpresponse/
│   │   │   │   ├── httpresponse.go
│   │   │   │   ├── httpresponse_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── ifaceassert/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── ifaceassert/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── ifaceassert.go
│   │   │   │   ├── ifaceassert_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── inline/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── inline/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── inline.go
│   │   │   │   ├── inline_test.go
│   │   │   │   ├── issue77844_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   ├── a.go.golden
│   │   │   │           │   └── internal/
│   │   │   │           │       └── d.go
│   │   │   │           ├── b/
│   │   │   │           │   ├── b.go
│   │   │   │           │   └── b.go.golden
│   │   │   │           ├── binding_false/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           ├── binding_true/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           ├── c/
│   │   │   │           │   └── c.go
│   │   │   │           ├── directive/
│   │   │   │           │   ├── directive.go
│   │   │   │           │   └── directive.go.golden
│   │   │   │           ├── issue76190.txtar
│   │   │   │           ├── issue77610.txtar
│   │   │   │           ├── issue77844.txtar
│   │   │   │           └── rmimport/
│   │   │   │               ├── rmimport.go
│   │   │   │               └── rmimport.go.golden
│   │   │   ├── inspect/
│   │   │   │   └── inspect.go
│   │   │   ├── internal/
│   │   │   │   └── gofixdirective/
│   │   │   │       └── gofixdirective.go
│   │   │   ├── loopclosure/
│   │   │   │   ├── doc.go
│   │   │   │   ├── loopclosure.go
│   │   │   │   ├── loopclosure_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── b.go
│   │   │   │           ├── golang.org/
│   │   │   │           │   └── x/
│   │   │   │           │       └── sync/
│   │   │   │           │           └── errgroup/
│   │   │   │           │               └── errgroup.go
│   │   │   │           ├── subtests/
│   │   │   │           │   └── subtest.go
│   │   │   │           ├── typeparams/
│   │   │   │           │   └── typeparams.go
│   │   │   │           └── versions/
│   │   │   │               ├── go18.txtar
│   │   │   │               └── go22.txtar
│   │   │   ├── lostcancel/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── lostcancel/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── lostcancel.go
│   │   │   │   ├── lostcancel_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── modernize/
│   │   │   │   ├── any.go
│   │   │   │   ├── atomictypes.go
│   │   │   │   ├── bloop.go
│   │   │   │   ├── cmd/
│   │   │   │   │   └── modernize/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── errorsastype.go
│   │   │   │   ├── fmtappendf.go
│   │   │   │   ├── forvar.go
│   │   │   │   ├── maps.go
│   │   │   │   ├── minmax.go
│   │   │   │   ├── modernize.go
│   │   │   │   ├── modernize_test.go
│   │   │   │   ├── newexpr.go
│   │   │   │   ├── omitzero.go
│   │   │   │   ├── plusbuild.go
│   │   │   │   ├── rangeint.go
│   │   │   │   ├── reflect.go
│   │   │   │   ├── slices.go
│   │   │   │   ├── slicescontains.go
│   │   │   │   ├── slicesdelete.go
│   │   │   │   ├── sortslice.go
│   │   │   │   ├── stditerators.go
│   │   │   │   ├── stringsbuilder.go
│   │   │   │   ├── stringscut.go
│   │   │   │   ├── stringscutprefix.go
│   │   │   │   ├── stringsseq.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── any/
│   │   │   │   │       │   ├── any.go
│   │   │   │   │       │   ├── any.go.golden
│   │   │   │   │       │   ├── generated.go
│   │   │   │   │       │   └── generated.go.golden
│   │   │   │   │       ├── appendclipped/
│   │   │   │   │       │   ├── appendclipped.go
│   │   │   │   │       │   ├── appendclipped.go.golden
│   │   │   │   │       │   ├── bytesclone.go
│   │   │   │   │       │   └── bytesclone.go.golden
│   │   │   │   │       ├── atomictypes/
│   │   │   │   │       │   ├── atomic.go
│   │   │   │   │       │   ├── atomic.go.golden
│   │   │   │   │       │   ├── atomic_shadow.go
│   │   │   │   │       │   ├── atomic_shadow.go.golden
│   │   │   │   │       │   ├── go118/
│   │   │   │   │       │   │   ├── atomic_go118.go
│   │   │   │   │       │   │   └── atomic_go118.go.golden
│   │   │   │   │       │   ├── go120/
│   │   │   │   │       │   │   ├── atomic_go120.go
│   │   │   │   │       │   │   └── atomic_go120.go.golden
│   │   │   │   │       │   └── ignored/
│   │   │   │   │       │       ├── atomic.go
│   │   │   │   │       │       ├── atomic.go.golden
│   │   │   │   │       │       └── atomic_ignored.go
│   │   │   │   │       ├── bloop/
│   │   │   │   │       │   ├── bloop.go
│   │   │   │   │       │   ├── bloop_test.go
│   │   │   │   │       │   └── bloop_test.go.golden
│   │   │   │   │       ├── errorsastype/
│   │   │   │   │       │   ├── dotimport/
│   │   │   │   │       │   │   ├── a.go
│   │   │   │   │       │   │   └── a.go.golden
│   │   │   │   │       │   ├── errorsastype.go
│   │   │   │   │       │   └── errorsastype.go.golden
│   │   │   │   │       ├── fieldsseq/
│   │   │   │   │       │   ├── fieldsseq.go
│   │   │   │   │       │   ├── fieldsseq.go.golden
│   │   │   │   │       │   └── fieldsseq_go123.go
│   │   │   │   │       ├── fmtappendf/
│   │   │   │   │       │   ├── fmtappendf.go
│   │   │   │   │       │   └── fmtappendf.go.golden
│   │   │   │   │       ├── forvar/
│   │   │   │   │       │   ├── forvar.go
│   │   │   │   │       │   └── forvar.go.golden
│   │   │   │   │       ├── mapsloop/
│   │   │   │   │       │   ├── mapsloop.go
│   │   │   │   │       │   ├── mapsloop.go.golden
│   │   │   │   │       │   ├── mapsloop_dot.go
│   │   │   │   │       │   └── mapsloop_dot.go.golden
│   │   │   │   │       ├── minmax/
│   │   │   │   │       │   ├── go120/
│   │   │   │   │       │   │   ├── minmax.go
│   │   │   │   │       │   │   ├── minmax_go120.go
│   │   │   │   │       │   │   └── minmax_go120.go.golden
│   │   │   │   │       │   ├── minmax.go
│   │   │   │   │       │   ├── minmax.go.golden
│   │   │   │   │       │   ├── nonstrict/
│   │   │   │   │       │   │   ├── nonstrict.go
│   │   │   │   │       │   │   └── nonstrict.go.golden
│   │   │   │   │       │   ├── userdefined/
│   │   │   │   │       │   │   ├── userdefined.go
│   │   │   │   │       │   │   └── userdefined.go.golden
│   │   │   │   │       │   ├── wrongoperators/
│   │   │   │   │       │   │   ├── wrongoperators.go
│   │   │   │   │       │   │   └── wrongoperators.go.golden
│   │   │   │   │       │   └── wrongreturn/
│   │   │   │   │       │       ├── wrongreturn.go
│   │   │   │   │       │       └── wrongreturn.go.golden
│   │   │   │   │       ├── newexpr/
│   │   │   │   │       │   ├── newexpr.go
│   │   │   │   │       │   ├── newexpr.go.golden
│   │   │   │   │       │   └── newexpr_go125.go
│   │   │   │   │       ├── omitzero/
│   │   │   │   │       │   ├── kube/
│   │   │   │   │       │   │   └── kube.go
│   │   │   │   │       │   ├── omitzero.go
│   │   │   │   │       │   └── omitzero.go.golden
│   │   │   │   │       ├── plusbuild/
│   │   │   │   │       │   ├── plusbuild.go
│   │   │   │   │       │   ├── plusbuild.go.golden
│   │   │   │   │       │   └── plusbuild2.go
│   │   │   │   │       ├── rangeint/
│   │   │   │   │       │   ├── a/
│   │   │   │   │       │   │   └── a.go
│   │   │   │   │       │   ├── rangeint.go
│   │   │   │   │       │   └── rangeint.go.golden
│   │   │   │   │       ├── reflecttypefor/
│   │   │   │   │       │   ├── reflecttypefor.go
│   │   │   │   │       │   └── reflecttypefor.go.golden
│   │   │   │   │       ├── slicescontains/
│   │   │   │   │       │   ├── slicescontains.go
│   │   │   │   │       │   └── slicescontains.go.golden
│   │   │   │   │       ├── slicesdelete/
│   │   │   │   │       │   ├── slicesdelete.go
│   │   │   │   │       │   └── slicesdelete.go.golden
│   │   │   │   │       ├── slicessort/
│   │   │   │   │       │   ├── slicessort.go
│   │   │   │   │       │   ├── slicessort.go.golden
│   │   │   │   │       │   ├── slicessort_dot.go
│   │   │   │   │       │   └── slicessort_dot.go.golden
│   │   │   │   │       ├── splitseq/
│   │   │   │   │       │   ├── splitseq.go
│   │   │   │   │       │   ├── splitseq.go.golden
│   │   │   │   │       │   └── splitseq_go123.go
│   │   │   │   │       ├── stditerators/
│   │   │   │   │       │   ├── stditerators.go
│   │   │   │   │       │   └── stditerators.go.golden
│   │   │   │   │       ├── stringsbuilder/
│   │   │   │   │       │   ├── stringsbuilder.go
│   │   │   │   │       │   └── stringsbuilder.go.golden
│   │   │   │   │       ├── stringscut/
│   │   │   │   │       │   ├── stringscut.go
│   │   │   │   │       │   └── stringscut.go.golden
│   │   │   │   │       ├── stringscutprefix/
│   │   │   │   │       │   ├── bytescutprefix/
│   │   │   │   │       │   │   ├── bytescutprefix.go
│   │   │   │   │       │   │   ├── bytescutprefix.go.golden
│   │   │   │   │       │   │   ├── bytescutprefix_dot.go
│   │   │   │   │       │   │   └── bytescutprefix_dot.go.golden
│   │   │   │   │       │   ├── stringscutprefix.go
│   │   │   │   │       │   ├── stringscutprefix.go.golden
│   │   │   │   │       │   ├── stringscutprefix_dot.go
│   │   │   │   │       │   └── stringscutprefix_dot.go.golden
│   │   │   │   │       ├── testingcontext/
│   │   │   │   │       │   ├── testingcontext.go
│   │   │   │   │       │   ├── testingcontext_test.go
│   │   │   │   │       │   └── testingcontext_test.go.golden
│   │   │   │   │       ├── unsafefuncs/
│   │   │   │   │       │   ├── unsafefuncs.go
│   │   │   │   │       │   └── unsafefuncs.go.golden
│   │   │   │   │       └── waitgroupgo/
│   │   │   │   │           ├── waitgroup.go
│   │   │   │   │           ├── waitgroup.go.golden
│   │   │   │   │           ├── waitgroup_alias.go
│   │   │   │   │           ├── waitgroup_alias.go.golden
│   │   │   │   │           ├── waitgroup_dot.go
│   │   │   │   │           └── waitgroup_dot.go.golden
│   │   │   │   ├── testingcontext.go
│   │   │   │   ├── unsafefuncs.go
│   │   │   │   └── waitgroupgo.go
│   │   │   ├── nilfunc/
│   │   │   │   ├── doc.go
│   │   │   │   ├── nilfunc.go
│   │   │   │   ├── nilfunc_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── nilness/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── nilness/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── nilness.go
│   │   │   │   ├── nilness_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           ├── c/
│   │   │   │           │   └── c.go
│   │   │   │           └── d/
│   │   │   │               └── d.go
│   │   │   ├── pkgfact/
│   │   │   │   ├── pkgfact.go
│   │   │   │   ├── pkgfact_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           └── c/
│   │   │   │               └── c.go
│   │   │   ├── printf/
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── printf.go
│   │   │   │   ├── printf_test.go
│   │   │   │   ├── testdata/
│   │   │   │   │   ├── nonconst_go123.txtar
│   │   │   │   │   ├── nonconst_go124.txtar
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── a2.go
│   │   │   │   │       ├── b/
│   │   │   │   │       │   └── b.go
│   │   │   │   │       ├── issue68744/
│   │   │   │   │       │   └── issue68744.go
│   │   │   │   │       ├── issue70572/
│   │   │   │   │       │   └── issue70572.go
│   │   │   │   │       ├── issue72850/
│   │   │   │   │       │   ├── a_go125.go
│   │   │   │   │       │   └── a_go126.go
│   │   │   │   │       ├── issue76616/
│   │   │   │   │       │   └── issue76616.go
│   │   │   │   │       ├── nofmt/
│   │   │   │   │       │   └── nofmt.go
│   │   │   │   │       ├── nonconst/
│   │   │   │   │       │   └── nonconst.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           ├── diagnostics.go
│   │   │   │   │           └── wrappers.go
│   │   │   │   └── types.go
│   │   │   ├── reflectvaluecompare/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── reflectvaluecompare/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── reflectvaluecompare.go
│   │   │   │   ├── reflectvaluecompare_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── shadow/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── shadow/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── shadow.go
│   │   │   │   ├── shadow_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── shift/
│   │   │   │   ├── dead.go
│   │   │   │   ├── shift.go
│   │   │   │   ├── shift_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── sigchanyzer/
│   │   │   │   ├── doc.go
│   │   │   │   ├── sigchanyzer.go
│   │   │   │   ├── sigchanyzer_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── slog/
│   │   │   │   ├── doc.go
│   │   │   │   ├── slog.go
│   │   │   │   ├── slog_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── b/
│   │   │   │               └── b.go
│   │   │   ├── sortslice/
│   │   │   │   ├── analyzer.go
│   │   │   │   ├── analyzer_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── stdmethods/
│   │   │   │   ├── doc.go
│   │   │   │   ├── stdmethods.go
│   │   │   │   ├── stdmethods_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── b.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── stdversion/
│   │   │   │   ├── main.go
│   │   │   │   ├── stdversion.go
│   │   │   │   ├── stdversion_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── test.txtar
│   │   │   ├── stringintconv/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── stringintconv/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── string.go
│   │   │   │   ├── string_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── fix/
│   │   │   │           │   ├── fix.go
│   │   │   │           │   ├── fix.go.golden
│   │   │   │           │   ├── fixdot.go
│   │   │   │           │   ├── fixdot.go.golden
│   │   │   │           │   ├── fixnamed.go
│   │   │   │           │   └── fixnamed.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── structtag/
│   │   │   │   ├── structtag.go
│   │   │   │   ├── structtag_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               └── b/
│   │   │   │                   └── b.go
│   │   │   ├── testinggoroutine/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── b.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           └── typeparams.go
│   │   │   │   ├── testinggoroutine.go
│   │   │   │   ├── testinggoroutine_test.go
│   │   │   │   └── util.go
│   │   │   ├── tests/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   ├── a_test.go
│   │   │   │   │       │   ├── ax_test.go
│   │   │   │   │       │   └── go118_test.go
│   │   │   │   │       ├── b/
│   │   │   │   │       │   └── b.go
│   │   │   │   │       ├── b_x_test/
│   │   │   │   │       │   └── b_test.go
│   │   │   │   │       ├── divergent/
│   │   │   │   │       │   ├── buf.go
│   │   │   │   │       │   └── buf_test.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           ├── typeparams.go
│   │   │   │   │           └── typeparams_test.go
│   │   │   │   ├── tests.go
│   │   │   │   └── tests_test.go
│   │   │   ├── timeformat/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── a.go.golden
│   │   │   │   │       └── b/
│   │   │   │   │           └── b.go
│   │   │   │   ├── timeformat.go
│   │   │   │   └── timeformat_test.go
│   │   │   ├── unmarshal/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── unmarshal/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   └── a.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           └── typeparams.go
│   │   │   │   ├── unmarshal.go
│   │   │   │   └── unmarshal_test.go
│   │   │   ├── unreachable/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       └── a/
│   │   │   │   │           ├── a.go
│   │   │   │   │           └── a.go.golden
│   │   │   │   ├── unreachable.go
│   │   │   │   └── unreachable_test.go
│   │   │   ├── unsafeptr/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── issue40701.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           └── typeparams.go
│   │   │   │   ├── unsafeptr.go
│   │   │   │   └── unsafeptr_test.go
│   │   │   ├── unusedresult/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── unusedresult/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   └── a.go
│   │   │   │   │       └── typeparams/
│   │   │   │   │           ├── typeparams.go
│   │   │   │   │           └── userdefs/
│   │   │   │   │               └── userdefs.go
│   │   │   │   ├── unusedresult.go
│   │   │   │   └── unusedresult_test.go
│   │   │   ├── unusedwrite/
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   └── unusedwrite.go
│   │   │   │   │       └── importsunsafe/
│   │   │   │   │           └── i.go
│   │   │   │   ├── unusedwrite.go
│   │   │   │   └── unusedwrite_test.go
│   │   │   ├── usesgenerics/
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   └── a.go
│   │   │   │   │       ├── b/
│   │   │   │   │       │   └── b.go
│   │   │   │   │       ├── c/
│   │   │   │   │       │   └── c.go
│   │   │   │   │       └── d/
│   │   │   │   │           └── d.go
│   │   │   │   ├── usesgenerics.go
│   │   │   │   └── usesgenerics_test.go
│   │   │   └── waitgroup/
│   │   │       ├── doc.go
│   │   │       ├── main.go
│   │   │       ├── testdata/
│   │   │       │   └── src/
│   │   │       │       └── a/
│   │   │       │           └── a.go
│   │   │       ├── waitgroup.go
│   │   │       └── waitgroup_test.go
│   │   ├── singlechecker/
│   │   │   └── singlechecker.go
│   │   ├── unitchecker/
│   │   │   ├── export_test.go
│   │   │   ├── main.go
│   │   │   ├── separate_test.go
│   │   │   ├── unitchecker.go
│   │   │   ├── unitchecker_test.go
│   │   │   └── vet_std_test.go
│   │   ├── validate.go
│   │   └── validate_test.go
│   ├── ast/
│   │   ├── astutil/
│   │   │   ├── enclosing.go
│   │   │   ├── enclosing_test.go
│   │   │   ├── imports.go
│   │   │   ├── imports_test.go
│   │   │   ├── rewrite.go
│   │   │   ├── rewrite_test.go
│   │   │   └── util.go
│   │   ├── edge/
│   │   │   └── edge.go
│   │   └── inspector/
│   │       ├── cursor.go
│   │       ├── cursor_test.go
│   │       ├── inspector.go
│   │       ├── inspector_test.go
│   │       ├── iter.go
│   │       ├── iter_test.go
│   │       ├── typeof.go
│   │       └── walk.go
│   ├── buildutil/
│   │   ├── allpackages.go
│   │   ├── allpackages_test.go
│   │   ├── fakecontext.go
│   │   ├── overlay.go
│   │   ├── overlay_test.go
│   │   ├── tags.go
│   │   ├── tags_test.go
│   │   ├── util.go
│   │   ├── util_test.go
│   │   └── util_windows_test.go
│   ├── callgraph/
│   │   ├── callgraph.go
│   │   ├── callgraph_test.go
│   │   ├── cha/
│   │   │   ├── cha.go
│   │   │   ├── cha_test.go
│   │   │   └── testdata/
│   │   │       ├── func.go
│   │   │       ├── generics.go
│   │   │       ├── iface.go
│   │   │       ├── issue23925.go
│   │   │       └── recv.go
│   │   ├── internal/
│   │   │   └── chautil/
│   │   │       └── lazy.go
│   │   ├── rta/
│   │   │   ├── rta.go
│   │   │   ├── rta_test.go
│   │   │   └── testdata/
│   │   │       ├── func.txtar
│   │   │       ├── generics.txtar
│   │   │       ├── iface.txtar
│   │   │       ├── multipkgs.txtar
│   │   │       ├── reflectcall.txtar
│   │   │       └── rtype.txtar
│   │   ├── static/
│   │   │   ├── static.go
│   │   │   └── static_test.go
│   │   ├── util.go
│   │   └── vta/
│   │       ├── graph.go
│   │       ├── graph_test.go
│   │       ├── helpers_test.go
│   │       ├── initial.go
│   │       ├── internal/
│   │       │   └── trie/
│   │       │       ├── bits.go
│   │       │       ├── bits_test.go
│   │       │       ├── builder.go
│   │       │       ├── op_test.go
│   │       │       ├── scope.go
│   │       │       ├── trie.go
│   │       │       └── trie_test.go
│   │       ├── propagation.go
│   │       ├── propagation_test.go
│   │       ├── testdata/
│   │       │   └── src/
│   │       │       ├── arrays_generics.go
│   │       │       ├── callgraph_collections.go
│   │       │       ├── callgraph_comma_maps.go
│   │       │       ├── callgraph_field_funcs.go
│   │       │       ├── callgraph_fields.go
│   │       │       ├── callgraph_generics.go
│   │       │       ├── callgraph_ho.go
│   │       │       ├── callgraph_interfaces.go
│   │       │       ├── callgraph_issue_57756.go
│   │       │       ├── callgraph_nested_ptr.go
│   │       │       ├── callgraph_pointers.go
│   │       │       ├── callgraph_range_over_func.go
│   │       │       ├── callgraph_recursive_types.go
│   │       │       ├── callgraph_static.go
│   │       │       ├── callgraph_type_aliases.go
│   │       │       ├── channels.go
│   │       │       ├── closures.go
│   │       │       ├── d/
│   │       │       │   └── d.go
│   │       │       ├── dynamic_calls.go
│   │       │       ├── fields.go
│   │       │       ├── function_alias.go
│   │       │       ├── generic_channels.go
│   │       │       ├── go117.go
│   │       │       ├── issue63146.go
│   │       │       ├── maps.go
│   │       │       ├── node_uniqueness.go
│   │       │       ├── panic.go
│   │       │       ├── phi.go
│   │       │       ├── phi_alias.go
│   │       │       ├── ranges.go
│   │       │       ├── returns.go
│   │       │       ├── select.go
│   │       │       ├── simple.go
│   │       │       ├── static_calls.go
│   │       │       ├── store.go
│   │       │       ├── store_load_alias.go
│   │       │       ├── stores_arrays.go
│   │       │       ├── t/
│   │       │       │   └── t.go
│   │       │       ├── type_assertions.go
│   │       │       └── type_conversions.go
│   │       ├── utils.go
│   │       ├── vta.go
│   │       └── vta_test.go
│   ├── cfg/
│   │   ├── builder.go
│   │   ├── cfg.go
│   │   ├── cfg_test.go
│   │   └── main.go
│   ├── gccgoexportdata/
│   │   ├── gccgoexportdata.go
│   │   ├── gccgoexportdata_test.go
│   │   └── testdata/
│   │       ├── errors.gox
│   │       ├── long.a
│   │       └── short.a
│   ├── gcexportdata/
│   │   ├── example_test.go
│   │   ├── gcexportdata.go
│   │   ├── importer.go
│   │   └── main.go
│   ├── internal/
│   │   ├── cgo/
│   │   │   ├── cgo.go
│   │   │   └── cgo_pkgconfig.go
│   │   └── gccgoimporter/
│   │       ├── ar.go
│   │       ├── backdoor.go
│   │       ├── gccgoinstallation.go
│   │       ├── gccgoinstallation_test.go
│   │       ├── importer.go
│   │       ├── importer_test.go
│   │       ├── newInterface10.go
│   │       ├── newInterface11.go
│   │       ├── parser.go
│   │       ├── parser_test.go
│   │       ├── testdata/
│   │       │   ├── aliases.go
│   │       │   ├── aliases.gox
│   │       │   ├── complexnums.go
│   │       │   ├── complexnums.gox
│   │       │   ├── conversions.go
│   │       │   ├── conversions.gox
│   │       │   ├── escapeinfo.go
│   │       │   ├── escapeinfo.gox
│   │       │   ├── imports.go
│   │       │   ├── imports.gox
│   │       │   ├── issue27856.go
│   │       │   ├── issue27856.gox
│   │       │   ├── issue29198.go
│   │       │   ├── issue29198.gox
│   │       │   ├── issue30628.go
│   │       │   ├── issue30628.gox
│   │       │   ├── issue31540.go
│   │       │   ├── issue31540.gox
│   │       │   ├── issue34182.go
│   │       │   ├── issue34182.gox
│   │       │   ├── libimportsar.a
│   │       │   ├── nointerface.go
│   │       │   ├── nointerface.gox
│   │       │   ├── notinheap.go
│   │       │   ├── notinheap.gox
│   │       │   ├── pointer.go
│   │       │   ├── pointer.gox
│   │       │   ├── time.gox
│   │       │   ├── unicode.gox
│   │       │   └── v1reflect.gox
│   │       └── testenv_test.go
│   ├── loader/
│   │   ├── doc.go
│   │   ├── loader.go
│   │   ├── loader_test.go
│   │   ├── stdlib_test.go
│   │   ├── testdata/
│   │   │   ├── a.go
│   │   │   ├── b.go
│   │   │   ├── badpkgdecl.go
│   │   │   └── issue46877/
│   │   │       ├── x.go
│   │   │       └── x.h
│   │   └── util.go
│   ├── packages/
│   │   ├── doc.go
│   │   ├── example_test.go
│   │   ├── external.go
│   │   ├── golist.go
│   │   ├── golist_overlay.go
│   │   ├── gopackages/
│   │   │   └── main.go
│   │   ├── internal/
│   │   │   ├── linecount/
│   │   │   │   └── linecount.go
│   │   │   └── nodecount/
│   │   │       └── nodecount.go
│   │   ├── loadmode_string.go
│   │   ├── overlay_test.go
│   │   ├── packages.go
│   │   ├── packages_test.go
│   │   ├── stdlib_test.go
│   │   └── visit.go
│   ├── ssa/
│   │   ├── TODO
│   │   ├── block.go
│   │   ├── blockopt.go
│   │   ├── builder.go
│   │   ├── builder_generic_test.go
│   │   ├── builder_test.go
│   │   ├── const.go
│   │   ├── const_test.go
│   │   ├── create.go
│   │   ├── doc.go
│   │   ├── dom.go
│   │   ├── dom_test.go
│   │   ├── emit.go
│   │   ├── example_test.go
│   │   ├── func.go
│   │   ├── instantiate.go
│   │   ├── instantiate_test.go
│   │   ├── interp/
│   │   │   ├── external.go
│   │   │   ├── interp.go
│   │   │   ├── interp_test.go
│   │   │   ├── map.go
│   │   │   ├── ops.go
│   │   │   ├── rangefunc_test.go
│   │   │   ├── reflect.go
│   │   │   ├── testdata/
│   │   │   │   ├── boundmeth.go
│   │   │   │   ├── complit.go
│   │   │   │   ├── convert.go
│   │   │   │   ├── coverage.go
│   │   │   │   ├── deepequal.go
│   │   │   │   ├── defer.go
│   │   │   │   ├── fieldprom.go
│   │   │   │   ├── fixedbugs/
│   │   │   │   │   ├── issue52342.go
│   │   │   │   │   ├── issue52835.go
│   │   │   │   │   ├── issue55086.go
│   │   │   │   │   ├── issue55115.go
│   │   │   │   │   ├── issue66783.go
│   │   │   │   │   ├── issue69298.go
│   │   │   │   │   └── issue69929.go
│   │   │   │   ├── forvarlifetime_go122.go
│   │   │   │   ├── forvarlifetime_old.go
│   │   │   │   ├── ifaceconv.go
│   │   │   │   ├── ifaceprom.go
│   │   │   │   ├── initorder.go
│   │   │   │   ├── methprom.go
│   │   │   │   ├── minmax.go
│   │   │   │   ├── mrvchain.go
│   │   │   │   ├── newexpr_go126.go
│   │   │   │   ├── range.go
│   │   │   │   ├── rangefunc.go
│   │   │   │   ├── rangeoverint.go
│   │   │   │   ├── rangevarlifetime_go122.go
│   │   │   │   ├── rangevarlifetime_old.go
│   │   │   │   ├── recover.go
│   │   │   │   ├── reflect.go
│   │   │   │   ├── slice2array.go
│   │   │   │   ├── slice2arrayptr.go
│   │   │   │   ├── src/
│   │   │   │   │   ├── encoding/
│   │   │   │   │   │   └── encoding.go
│   │   │   │   │   ├── errors/
│   │   │   │   │   │   └── errors.go
│   │   │   │   │   ├── fmt/
│   │   │   │   │   │   └── fmt.go
│   │   │   │   │   ├── io/
│   │   │   │   │   │   └── io.go
│   │   │   │   │   ├── log/
│   │   │   │   │   │   └── log.go
│   │   │   │   │   ├── math/
│   │   │   │   │   │   └── math.go
│   │   │   │   │   ├── os/
│   │   │   │   │   │   └── os.go
│   │   │   │   │   ├── reflect/
│   │   │   │   │   │   ├── deepequal.go
│   │   │   │   │   │   └── reflect.go
│   │   │   │   │   ├── runtime/
│   │   │   │   │   │   └── runtime.go
│   │   │   │   │   ├── sort/
│   │   │   │   │   │   └── sort.go
│   │   │   │   │   ├── strconv/
│   │   │   │   │   │   └── strconv.go
│   │   │   │   │   ├── strings/
│   │   │   │   │   │   └── strings.go
│   │   │   │   │   ├── sync/
│   │   │   │   │   │   └── sync.go
│   │   │   │   │   ├── time/
│   │   │   │   │   │   └── time.go
│   │   │   │   │   ├── unicode/
│   │   │   │   │   │   └── utf8/
│   │   │   │   │   │       └── utf8.go
│   │   │   │   │   └── unsafe/
│   │   │   │   │       └── unsafe.go
│   │   │   │   ├── static.go
│   │   │   │   ├── typeassert.go
│   │   │   │   ├── width32.go
│   │   │   │   └── zeros.go
│   │   │   └── value.go
│   │   ├── lift.go
│   │   ├── lvalue.go
│   │   ├── methods.go
│   │   ├── methods_test.go
│   │   ├── mode.go
│   │   ├── print.go
│   │   ├── sanity.go
│   │   ├── source.go
│   │   ├── source_test.go
│   │   ├── ssa.go
│   │   ├── ssautil/
│   │   │   ├── deprecated.go
│   │   │   ├── deprecated_test.go
│   │   │   ├── load.go
│   │   │   ├── load_test.go
│   │   │   ├── switch.go
│   │   │   ├── switch_test.go
│   │   │   ├── testdata/
│   │   │   │   └── switches.txtar
│   │   │   └── visit.go
│   │   ├── stdlib_test.go
│   │   ├── subst.go
│   │   ├── subst_test.go
│   │   ├── task.go
│   │   ├── testdata/
│   │   │   ├── fixedbugs/
│   │   │   │   ├── issue66783a.go
│   │   │   │   ├── issue66783b.go
│   │   │   │   └── issue73594.go
│   │   │   ├── indirect.txtar
│   │   │   ├── objlookup.go
│   │   │   ├── src/
│   │   │   │   ├── README.txt
│   │   │   │   ├── bytes/
│   │   │   │   │   └── bytes.go
│   │   │   │   ├── context/
│   │   │   │   │   └── context.go
│   │   │   │   ├── encoding/
│   │   │   │   │   ├── encoding.go
│   │   │   │   │   ├── json/
│   │   │   │   │   │   └── json.go
│   │   │   │   │   └── xml/
│   │   │   │   │       └── xml.go
│   │   │   │   ├── errors/
│   │   │   │   │   └── errors.go
│   │   │   │   ├── fmt/
│   │   │   │   │   └── fmt.go
│   │   │   │   ├── io/
│   │   │   │   │   └── io.go
│   │   │   │   ├── log/
│   │   │   │   │   └── log.go
│   │   │   │   ├── math/
│   │   │   │   │   └── math.go
│   │   │   │   ├── os/
│   │   │   │   │   └── os.go
│   │   │   │   ├── reflect/
│   │   │   │   │   └── reflect.go
│   │   │   │   ├── runtime/
│   │   │   │   │   └── runtime.go
│   │   │   │   ├── sort/
│   │   │   │   │   └── sort.go
│   │   │   │   ├── strconv/
│   │   │   │   │   └── strconv.go
│   │   │   │   ├── strings/
│   │   │   │   │   └── strings.go
│   │   │   │   ├── sync/
│   │   │   │   │   ├── atomic/
│   │   │   │   │   │   └── atomic.go
│   │   │   │   │   └── sync.go
│   │   │   │   ├── time/
│   │   │   │   │   └── time.go
│   │   │   │   └── unsafe/
│   │   │   │       └── unsafe.go
│   │   │   ├── structconv.go
│   │   │   └── valueforexpr.go
│   │   ├── testutil_test.go
│   │   ├── typeset.go
│   │   ├── util.go
│   │   └── wrappers.go
│   └── types/
│       ├── internal/
│       │   └── play/
│       │       └── play.go
│       ├── objectpath/
│       │   ├── objectpath.go
│       │   ├── objectpath_go118_test.go
│       │   └── objectpath_test.go
│       └── typeutil/
│           ├── callee.go
│           ├── callee_test.go
│           ├── example_test.go
│           ├── imports.go
│           ├── imports_test.go
│           ├── map.go
│           ├── map_test.go
│           ├── methodsetcache.go
│           ├── ui.go
│           └── ui_test.go
├── go.mod
├── go.sum
├── gopls/
│   ├── README.md
│   ├── contributors.txt
│   ├── doc/
│   │   ├── README.md
│   │   ├── advanced.md
│   │   ├── analyzers.md
│   │   ├── assets/
│   │   │   ├── assets.go
│   │   │   └── go.mod
│   │   ├── codelenses.md
│   │   ├── command-line.md
│   │   ├── contributing.md
│   │   ├── daemon.md
│   │   ├── default.tmpl
│   │   ├── design/
│   │   │   ├── design.md
│   │   │   ├── implementation.md
│   │   │   └── integrating.md
│   │   ├── editor/
│   │   │   ├── emacs.md
│   │   │   ├── helix.md
│   │   │   ├── sublime.md
│   │   │   ├── vim.md
│   │   │   └── zed.md
│   │   ├── features/
│   │   │   ├── README.md
│   │   │   ├── assembly.md
│   │   │   ├── completion.md
│   │   │   ├── diagnostics.md
│   │   │   ├── index.md
│   │   │   ├── mcp.md
│   │   │   ├── modfiles.md
│   │   │   ├── navigation.md
│   │   │   ├── passive.md
│   │   │   ├── templates.md
│   │   │   ├── transformation.md
│   │   │   └── web.md
│   │   ├── index.md
│   │   ├── inlayHints.md
│   │   ├── release/
│   │   │   ├── README
│   │   │   ├── v0.16.0.md
│   │   │   ├── v0.17.0.md
│   │   │   ├── v0.18.0.md
│   │   │   ├── v0.19.0.md
│   │   │   ├── v0.20.0.md
│   │   │   ├── v0.21.0.md
│   │   │   └── v0.22.0.md
│   │   ├── settings.md
│   │   ├── troubleshooting.md
│   │   └── workspace.md
│   ├── go.mod
│   ├── go.sum
│   ├── integration/
│   │   └── govim/
│   │       ├── Dockerfile
│   │       ├── README.md
│   │       ├── artifacts.go
│   │       ├── cloudbuild.harness.yaml
│   │       ├── cloudbuild.yaml
│   │       ├── run_local.sh
│   │       └── run_tests_for_cloudbuild.sh
│   ├── internal/
│   │   ├── analysis/
│   │   │   ├── deprecated/
│   │   │   │   ├── deprecated.go
│   │   │   │   ├── deprecated_test.go
│   │   │   │   ├── doc.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── a.go
│   │   │   │               └── a_test.go
│   │   │   ├── embeddirective/
│   │   │   │   ├── doc.go
│   │   │   │   ├── embeddirective.go
│   │   │   │   ├── embeddirective_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── embedText
│   │   │   │               ├── import_missing.go
│   │   │   │               ├── import_missing.go.golden
│   │   │   │               ├── import_present.go
│   │   │   │               └── import_present_go120.go
│   │   │   ├── fillreturns/
│   │   │   │   ├── doc.go
│   │   │   │   ├── fillreturns.go
│   │   │   │   ├── fillreturns_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── fillstruct/
│   │   │   │   ├── fillstruct.go
│   │   │   │   ├── fillstruct_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           ├── b/
│   │   │   │           │   └── b.go
│   │   │   │           └── typeparams/
│   │   │   │               └── typeparams.go
│   │   │   ├── fillswitch/
│   │   │   │   ├── doc.go
│   │   │   │   ├── fillswitch.go
│   │   │   │   ├── fillswitch_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   └── a.go
│   │   │   │           └── b/
│   │   │   │               └── b.go
│   │   │   ├── infertypeargs/
│   │   │   │   ├── infertypeargs.go
│   │   │   │   ├── infertypeargs_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               ├── basic.go
│   │   │   │               ├── basic.go.golden
│   │   │   │               ├── imported/
│   │   │   │               │   └── imported.go
│   │   │   │               ├── imported.go
│   │   │   │               ├── imported.go.golden
│   │   │   │               ├── notypechange.go
│   │   │   │               └── notypechange.go.golden
│   │   │   ├── maprange/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── maprange/
│   │   │   │   │       └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── maprange.go
│   │   │   │   ├── maprange_test.go
│   │   │   │   └── testdata/
│   │   │   │       ├── basic.txtar
│   │   │   │       └── old.txtar
│   │   │   ├── modernize/
│   │   │   │   └── cmd/
│   │   │   │       └── modernize/
│   │   │   │           └── main.go
│   │   │   ├── nonewvars/
│   │   │   │   ├── doc.go
│   │   │   │   ├── nonewvars.go
│   │   │   │   ├── nonewvars_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── noresultvalues/
│   │   │   │   ├── doc.go
│   │   │   │   ├── noresultvalues.go
│   │   │   │   ├── noresultvalues_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               ├── a.go
│   │   │   │               └── a.go.golden
│   │   │   ├── recursiveiter/
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── recursiveiter.go
│   │   │   │   ├── recursiveiter_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           └── a/
│   │   │   │               └── a.go
│   │   │   ├── simplifycompositelit/
│   │   │   │   ├── doc.go
│   │   │   │   ├── simplifycompositelit.go
│   │   │   │   ├── simplifycompositelit_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           └── generatedcode/
│   │   │   │               ├── generatedcode.go
│   │   │   │               └── generatedcode.go.golden
│   │   │   ├── simplifyrange/
│   │   │   │   ├── doc.go
│   │   │   │   ├── simplifyrange.go
│   │   │   │   ├── simplifyrange_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           ├── generatedcode/
│   │   │   │           │   ├── generatedcode.go
│   │   │   │           │   └── generatedcode.go.golden
│   │   │   │           └── rangeoverfunc/
│   │   │   │               ├── rangeoverfunc.go
│   │   │   │               └── rangeoverfunc.go.golden
│   │   │   ├── simplifyslice/
│   │   │   │   ├── doc.go
│   │   │   │   ├── simplifyslice.go
│   │   │   │   ├── simplifyslice_test.go
│   │   │   │   └── testdata/
│   │   │   │       └── src/
│   │   │   │           ├── a/
│   │   │   │           │   ├── a.go
│   │   │   │           │   └── a.go.golden
│   │   │   │           ├── generatedcode/
│   │   │   │           │   ├── generatedcode.go
│   │   │   │           │   └── generatedcode.go.golden
│   │   │   │           └── typeparams/
│   │   │   │               ├── typeparams.go
│   │   │   │               └── typeparams.go.golden
│   │   │   ├── unusedfunc/
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── basic.txtar
│   │   │   │   ├── unusedfunc.go
│   │   │   │   └── unusedfunc_test.go
│   │   │   ├── unusedparams/
│   │   │   │   ├── cmd/
│   │   │   │   │   └── main.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── a/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── a.go.golden
│   │   │   │   │       ├── generatedcode/
│   │   │   │   │       │   ├── generatedcode.go
│   │   │   │   │       │   ├── generatedcode.go.golden
│   │   │   │   │       │   ├── nongeneratedcode.go
│   │   │   │   │       │   └── nongeneratedcode.go.golden
│   │   │   │   │       └── typeparams/
│   │   │   │   │           ├── typeparams.go
│   │   │   │   │           └── typeparams.go.golden
│   │   │   │   ├── unusedparams.go
│   │   │   │   └── unusedparams_test.go
│   │   │   ├── unusedvariable/
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       ├── assign/
│   │   │   │   │       │   ├── a.go
│   │   │   │   │       │   └── a.go.golden
│   │   │   │   │       └── decl/
│   │   │   │   │           ├── a.go
│   │   │   │   │           └── a.go.golden
│   │   │   │   ├── unusedvariable.go
│   │   │   │   └── unusedvariable_test.go
│   │   │   ├── writestring/
│   │   │   │   ├── doc.go
│   │   │   │   ├── main.go
│   │   │   │   ├── testdata/
│   │   │   │   │   └── src/
│   │   │   │   │       └── a/
│   │   │   │   │           ├── a.go
│   │   │   │   │           └── a.go.golden
│   │   │   │   ├── writestring.go
│   │   │   │   └── writestring_test.go
│   │   │   └── yield/
│   │   │       ├── doc.go
│   │   │       ├── main.go
│   │   │       ├── testdata/
│   │   │       │   └── src/
│   │   │       │       └── a/
│   │   │       │           └── a.go
│   │   │       ├── yield.go
│   │   │       └── yield_test.go
│   │   ├── bloom/
│   │   │   ├── filter.go
│   │   │   └── filter_test.go
│   │   ├── cache/
│   │   │   ├── analysis.go
│   │   │   ├── cache.go
│   │   │   ├── check.go
│   │   │   ├── constraints.go
│   │   │   ├── constraints_test.go
│   │   │   ├── debug.go
│   │   │   ├── diagnostics.go
│   │   │   ├── errors.go
│   │   │   ├── errors_test.go
│   │   │   ├── filemap.go
│   │   │   ├── filemap_test.go
│   │   │   ├── filterer.go
│   │   │   ├── fs_memoized.go
│   │   │   ├── fs_overlay.go
│   │   │   ├── future.go
│   │   │   ├── future_test.go
│   │   │   ├── imports.go
│   │   │   ├── keys.go
│   │   │   ├── load.go
│   │   │   ├── metadata/
│   │   │   │   ├── cycle_test.go
│   │   │   │   ├── graph.go
│   │   │   │   └── metadata.go
│   │   │   ├── methodsets/
│   │   │   │   └── methodsets.go
│   │   │   ├── mod.go
│   │   │   ├── mod_tidy.go
│   │   │   ├── mod_vuln.go
│   │   │   ├── os_darwin.go
│   │   │   ├── os_windows.go
│   │   │   ├── package.go
│   │   │   ├── parse.go
│   │   │   ├── parse_cache.go
│   │   │   ├── parse_cache_test.go
│   │   │   ├── parsego/
│   │   │   │   ├── file.go
│   │   │   │   ├── parse.go
│   │   │   │   ├── parse_test.go
│   │   │   │   ├── resolver.go
│   │   │   │   ├── resolver_compat.go
│   │   │   │   ├── resolver_gen.go
│   │   │   │   └── resolver_test.go
│   │   │   ├── port.go
│   │   │   ├── port_test.go
│   │   │   ├── session.go
│   │   │   ├── session_test.go
│   │   │   ├── snapshot.go
│   │   │   ├── source.go
│   │   │   ├── symbols/
│   │   │   │   └── symbols.go
│   │   │   ├── symbols.go
│   │   │   ├── testfuncs/
│   │   │   │   ├── match.go
│   │   │   │   └── tests.go
│   │   │   ├── typerefs/
│   │   │   │   ├── doc.go
│   │   │   │   ├── packageset.go
│   │   │   │   ├── pkggraph_test.go
│   │   │   │   ├── pkgrefs_test.go
│   │   │   │   ├── refs.go
│   │   │   │   └── refs_test.go
│   │   │   ├── view.go
│   │   │   ├── view_test.go
│   │   │   ├── workspace.go
│   │   │   └── xrefs/
│   │   │       └── xrefs.go
│   │   ├── clonetest/
│   │   │   ├── clonetest.go
│   │   │   └── clonetest_test.go
│   │   ├── cmd/
│   │   │   ├── call_hierarchy.go
│   │   │   ├── capabilities_test.go
│   │   │   ├── check.go
│   │   │   ├── cmd.go
│   │   │   ├── codeaction.go
│   │   │   ├── codelens.go
│   │   │   ├── counters.go
│   │   │   ├── definition.go
│   │   │   ├── execute.go
│   │   │   ├── folding_range.go
│   │   │   ├── format.go
│   │   │   ├── help_test.go
│   │   │   ├── highlight.go
│   │   │   ├── implementation.go
│   │   │   ├── imports.go
│   │   │   ├── info.go
│   │   │   ├── integration_test.go
│   │   │   ├── links.go
│   │   │   ├── mcp.go
│   │   │   ├── mcp_test.go
│   │   │   ├── parsespan.go
│   │   │   ├── prepare_rename.go
│   │   │   ├── references.go
│   │   │   ├── remote.go
│   │   │   ├── rename.go
│   │   │   ├── semantictokens.go
│   │   │   ├── serve.go
│   │   │   ├── signature.go
│   │   │   ├── span.go
│   │   │   ├── spanformat_test.go
│   │   │   ├── stats.go
│   │   │   ├── subcommands.go
│   │   │   ├── symbols.go
│   │   │   ├── usage/
│   │   │   │   ├── api-json.hlp
│   │   │   │   ├── bug.hlp
│   │   │   │   ├── call_hierarchy.hlp
│   │   │   │   ├── check.hlp
│   │   │   │   ├── codeaction.hlp
│   │   │   │   ├── codelens.hlp
│   │   │   │   ├── definition.hlp
│   │   │   │   ├── execute.hlp
│   │   │   │   ├── fix.hlp
│   │   │   │   ├── folding_ranges.hlp
│   │   │   │   ├── format.hlp
│   │   │   │   ├── help.hlp
│   │   │   │   ├── highlight.hlp
│   │   │   │   ├── implementation.hlp
│   │   │   │   ├── imports.hlp
│   │   │   │   ├── inspect.hlp
│   │   │   │   ├── licenses.hlp
│   │   │   │   ├── links.hlp
│   │   │   │   ├── mcp.hlp
│   │   │   │   ├── prepare_rename.hlp
│   │   │   │   ├── references.hlp
│   │   │   │   ├── remote.hlp
│   │   │   │   ├── rename.hlp
│   │   │   │   ├── semtok.hlp
│   │   │   │   ├── serve.hlp
│   │   │   │   ├── signature.hlp
│   │   │   │   ├── stats.hlp
│   │   │   │   ├── symbols.hlp
│   │   │   │   ├── usage-v.hlp
│   │   │   │   ├── usage.hlp
│   │   │   │   ├── version.hlp
│   │   │   │   ├── vulncheck.hlp
│   │   │   │   └── workspace_symbol.hlp
│   │   │   ├── vulncheck.go
│   │   │   └── workspace_symbol.go
│   │   ├── debug/
│   │   │   ├── flight.go
│   │   │   ├── flight_go124.go
│   │   │   ├── flight_unix.go
│   │   │   ├── info.go
│   │   │   ├── info_test.go
│   │   │   ├── log/
│   │   │   │   └── log.go
│   │   │   ├── metrics.go
│   │   │   ├── rpc.go
│   │   │   ├── serve.go
│   │   │   ├── template_test.go
│   │   │   └── trace.go
│   │   ├── doc/
│   │   │   ├── api.go
│   │   │   ├── api.json
│   │   │   └── generate/
│   │   │       ├── generate.go
│   │   │       └── generate_test.go
│   │   ├── file/
│   │   │   ├── file.go
│   │   │   ├── hash.go
│   │   │   ├── kind.go
│   │   │   └── modification.go
│   │   ├── filecache/
│   │   │   ├── filecache.go
│   │   │   └── filecache_test.go
│   │   ├── filewatcher/
│   │   │   ├── export_test.go
│   │   │   ├── filewatcher.go
│   │   │   ├── filewatcher_test.go
│   │   │   └── fsnotify_watcher.go
│   │   ├── fuzzy/
│   │   │   ├── input.go
│   │   │   ├── input_test.go
│   │   │   ├── matcher.go
│   │   │   ├── matcher_test.go
│   │   │   ├── self_test.go
│   │   │   ├── symbol.go
│   │   │   └── symbol_test.go
│   │   ├── goasm/
│   │   │   └── definition.go
│   │   ├── golang/
│   │   │   ├── add_import.go
│   │   │   ├── addtest.go
│   │   │   ├── assembly.go
│   │   │   ├── call_hierarchy.go
│   │   │   ├── change_quote.go
│   │   │   ├── change_signature.go
│   │   │   ├── code_lens.go
│   │   │   ├── codeaction.go
│   │   │   ├── comment.go
│   │   │   ├── compileropt.go
│   │   │   ├── completion/
│   │   │   │   ├── builtin.go
│   │   │   │   ├── completion.go
│   │   │   │   ├── deep_completion.go
│   │   │   │   ├── deep_completion_test.go
│   │   │   │   ├── definition.go
│   │   │   │   ├── format.go
│   │   │   │   ├── fuzz.go
│   │   │   │   ├── keywords.go
│   │   │   │   ├── labels.go
│   │   │   │   ├── literal.go
│   │   │   │   ├── newfile.go
│   │   │   │   ├── package.go
│   │   │   │   ├── package_test.go
│   │   │   │   ├── postfix_snippets.go
│   │   │   │   ├── printf.go
│   │   │   │   ├── printf_test.go
│   │   │   │   ├── snippet/
│   │   │   │   │   ├── snippet_builder.go
│   │   │   │   │   └── snippet_builder_test.go
│   │   │   │   ├── snippet.go
│   │   │   │   ├── statements.go
│   │   │   │   ├── unify.go
│   │   │   │   ├── unimported.go
│   │   │   │   └── util.go
│   │   │   ├── counters.go
│   │   │   ├── definition.go
│   │   │   ├── diagnostics.go
│   │   │   ├── embeddirective.go
│   │   │   ├── extract.go
│   │   │   ├── extracttofile.go
│   │   │   ├── fix.go
│   │   │   ├── folding_range.go
│   │   │   ├── format.go
│   │   │   ├── format_test.go
│   │   │   ├── freesymbols.go
│   │   │   ├── freesymbols_test.go
│   │   │   ├── highlight.go
│   │   │   ├── hover.go
│   │   │   ├── hover_test.go
│   │   │   ├── identifier.go
│   │   │   ├── identifier_test.go
│   │   │   ├── implementation.go
│   │   │   ├── implementation_test.go
│   │   │   ├── inlay_hint.go
│   │   │   ├── inline.go
│   │   │   ├── inline_all.go
│   │   │   ├── invertifcondition.go
│   │   │   ├── known_packages.go
│   │   │   ├── lines.go
│   │   │   ├── linkname.go
│   │   │   ├── modify_tags.go
│   │   │   ├── movetype.go
│   │   │   ├── origin.go
│   │   │   ├── pkgdoc.go
│   │   │   ├── references.go
│   │   │   ├── rename.go
│   │   │   ├── rename_check.go
│   │   │   ├── semtok.go
│   │   │   ├── signature_help.go
│   │   │   ├── snapshot.go
│   │   │   ├── splitpkg/
│   │   │   │   ├── graph.go
│   │   │   │   ├── splitpkg.go
│   │   │   │   └── splitpkg.html.tmpl
│   │   │   ├── stub.go
│   │   │   ├── stubmethods/
│   │   │   │   ├── stubcalledfunc.go
│   │   │   │   └── stubmethods.go
│   │   │   ├── symbols.go
│   │   │   ├── type_definition.go
│   │   │   ├── type_hierarchy.go
│   │   │   ├── types_format.go
│   │   │   ├── undeclared.go
│   │   │   ├── util.go
│   │   │   ├── workspace_symbol.go
│   │   │   └── workspace_symbol_test.go
│   │   ├── label/
│   │   │   └── keys.go
│   │   ├── licenses/
│   │   │   ├── gen-licenses.sh
│   │   │   ├── licenses.go
│   │   │   └── licenses_test.go
│   │   ├── lsprpc/
│   │   │   ├── autostart_default.go
│   │   │   ├── autostart_posix.go
│   │   │   ├── binder.go
│   │   │   ├── binder_test.go
│   │   │   ├── commandinterceptor_test.go
│   │   │   ├── dialer.go
│   │   │   ├── export_test.go
│   │   │   ├── goenv.go
│   │   │   ├── goenv_test.go
│   │   │   ├── lsprpc.go
│   │   │   ├── lsprpc_test.go
│   │   │   └── middleware_test.go
│   │   ├── mcp/
│   │   │   ├── context.go
│   │   │   ├── counters.go
│   │   │   ├── file_context.go
│   │   │   ├── file_diagnostics.go
│   │   │   ├── file_metadata.go
│   │   │   ├── instructions.md
│   │   │   ├── mcp.go
│   │   │   ├── mcp_test.go
│   │   │   ├── outline.go
│   │   │   ├── references.go
│   │   │   ├── rename_symbol.go
│   │   │   ├── search.go
│   │   │   ├── symbol_references.go
│   │   │   ├── vulncheck.go
│   │   │   ├── workspace.go
│   │   │   └── workspace_diagnostics.go
│   │   ├── mod/
│   │   │   ├── code_lens.go
│   │   │   ├── diagnostics.go
│   │   │   ├── format.go
│   │   │   ├── hover.go
│   │   │   ├── inlay_hint.go
│   │   │   └── references.go
│   │   ├── progress/
│   │   │   ├── progress.go
│   │   │   └── progress_test.go
│   │   ├── protocol/
│   │   │   ├── command/
│   │   │   │   ├── command_gen.go
│   │   │   │   ├── commandmeta/
│   │   │   │   │   └── meta.go
│   │   │   │   ├── gen/
│   │   │   │   │   └── gen.go
│   │   │   │   ├── generate.go
│   │   │   │   ├── interface.go
│   │   │   │   ├── interface_test.go
│   │   │   │   └── util.go
│   │   │   ├── context.go
│   │   │   ├── doc.go
│   │   │   ├── edits.go
│   │   │   ├── enums.go
│   │   │   ├── form.go
│   │   │   ├── generate/
│   │   │   │   ├── README.md
│   │   │   │   ├── generate.go
│   │   │   │   ├── main.go
│   │   │   │   ├── main_test.go
│   │   │   │   ├── output.go
│   │   │   │   ├── tables.go
│   │   │   │   ├── typenames.go
│   │   │   │   └── types.go
│   │   │   ├── json_test.go
│   │   │   ├── log.go
│   │   │   ├── mapper.go
│   │   │   ├── mapper_test.go
│   │   │   ├── protocol.go
│   │   │   ├── semtok/
│   │   │   │   ├── README.txt
│   │   │   │   └── semtok.go
│   │   │   ├── span.go
│   │   │   ├── tsclient.go
│   │   │   ├── tsdocument_changes.go
│   │   │   ├── tsinsertreplaceedit.go
│   │   │   ├── tsinsertreplaceedit_test.go
│   │   │   ├── tsjson.go
│   │   │   ├── tsprotocol.go
│   │   │   ├── tsserver.go
│   │   │   ├── uri.go
│   │   │   ├── uri_test.go
│   │   │   └── uri_windows_test.go
│   │   ├── server/
│   │   │   ├── assets/
│   │   │   │   ├── common.css
│   │   │   │   ├── common.js
│   │   │   │   ├── splitpkg.css
│   │   │   │   └── splitpkg.js
│   │   │   ├── call_hierarchy.go
│   │   │   ├── code_action.go
│   │   │   ├── code_lens.go
│   │   │   ├── command.go
│   │   │   ├── completion.go
│   │   │   ├── counters.go
│   │   │   ├── debug.go
│   │   │   ├── definition.go
│   │   │   ├── diagnostics.go
│   │   │   ├── folding_range.go
│   │   │   ├── format.go
│   │   │   ├── general.go
│   │   │   ├── highlight.go
│   │   │   ├── hover.go
│   │   │   ├── implementation.go
│   │   │   ├── inlay_hint.go
│   │   │   ├── link.go
│   │   │   ├── prompt.go
│   │   │   ├── prompt_test.go
│   │   │   ├── references.go
│   │   │   ├── rename.go
│   │   │   ├── resolve.go
│   │   │   ├── selection_range.go
│   │   │   ├── semantic.go
│   │   │   ├── server.go
│   │   │   ├── signature_help.go
│   │   │   ├── symbols.go
│   │   │   ├── text_synchronization.go
│   │   │   ├── type_hierarchy.go
│   │   │   ├── unimplemented.go
│   │   │   ├── vulncheck_prompt.go
│   │   │   ├── vulncheck_prompt_test.go
│   │   │   ├── workspace.go
│   │   │   └── workspace_symbol.go
│   │   ├── settings/
│   │   │   ├── analysis.go
│   │   │   ├── codeactionkind.go
│   │   │   ├── default.go
│   │   │   ├── settings.go
│   │   │   ├── settings_test.go
│   │   │   ├── staticcheck.go
│   │   │   └── vet_test.go
│   │   ├── telemetry/
│   │   │   ├── counterpath.go
│   │   │   ├── counterpath_test.go
│   │   │   ├── latency.go
│   │   │   └── telemetry_test.go
│   │   ├── template/
│   │   │   ├── completion.go
│   │   │   ├── completion_test.go
│   │   │   ├── highlight.go
│   │   │   ├── implementations.go
│   │   │   ├── parse.go
│   │   │   ├── parse_test.go
│   │   │   └── symbols.go
│   │   ├── test/
│   │   │   ├── compare/
│   │   │   │   ├── text.go
│   │   │   │   └── text_test.go
│   │   │   ├── integration/
│   │   │   │   ├── bench/
│   │   │   │   │   ├── bench_test.go
│   │   │   │   │   ├── codeaction_test.go
│   │   │   │   │   ├── completion_test.go
│   │   │   │   │   ├── definition_test.go
│   │   │   │   │   ├── diagnostic_test.go
│   │   │   │   │   ├── didchange_test.go
│   │   │   │   │   ├── doc.go
│   │   │   │   │   ├── hover_test.go
│   │   │   │   │   ├── implementations_test.go
│   │   │   │   │   ├── imports_test.go
│   │   │   │   │   ├── iwl_test.go
│   │   │   │   │   ├── references_test.go
│   │   │   │   │   ├── reload_test.go
│   │   │   │   │   ├── rename_test.go
│   │   │   │   │   ├── repo_test.go
│   │   │   │   │   ├── stress_test.go
│   │   │   │   │   ├── tests_test.go
│   │   │   │   │   ├── typing_test.go
│   │   │   │   │   ├── unimported_test.go
│   │   │   │   │   └── workspace_symbols_test.go
│   │   │   │   ├── codelens/
│   │   │   │   │   └── codelens_test.go
│   │   │   │   ├── completion/
│   │   │   │   │   ├── completion18_test.go
│   │   │   │   │   ├── completion_test.go
│   │   │   │   │   ├── fixedbugs_test.go
│   │   │   │   │   └── postfix_snippet_test.go
│   │   │   │   ├── debug/
│   │   │   │   │   └── debug_test.go
│   │   │   │   ├── diagnostics/
│   │   │   │   │   ├── analysis_test.go
│   │   │   │   │   ├── builtin_test.go
│   │   │   │   │   ├── diagnostics_test.go
│   │   │   │   │   ├── golist_test.go
│   │   │   │   │   ├── gopackagesdriver_test.go
│   │   │   │   │   ├── invalidation_test.go
│   │   │   │   │   └── undeclared_test.go
│   │   │   │   ├── doc.go
│   │   │   │   ├── env.go
│   │   │   │   ├── env_test.go
│   │   │   │   ├── expectation.go
│   │   │   │   ├── fake/
│   │   │   │   │   ├── client.go
│   │   │   │   │   ├── doc.go
│   │   │   │   │   ├── edit.go
│   │   │   │   │   ├── edit_test.go
│   │   │   │   │   ├── editor.go
│   │   │   │   │   ├── editor_test.go
│   │   │   │   │   ├── glob/
│   │   │   │   │   │   ├── glob.go
│   │   │   │   │   │   └── glob_test.go
│   │   │   │   │   ├── proxy.go
│   │   │   │   │   ├── sandbox.go
│   │   │   │   │   ├── workdir.go
│   │   │   │   │   ├── workdir_test.go
│   │   │   │   │   └── workdir_windows.go
│   │   │   │   ├── hover/
│   │   │   │   │   └── hover_test.go
│   │   │   │   ├── inlayhints/
│   │   │   │   │   └── inlayhints_test.go
│   │   │   │   ├── misc/
│   │   │   │   │   ├── addtest_test.go
│   │   │   │   │   ├── call_hierarchy_test.go
│   │   │   │   │   ├── codeactions_test.go
│   │   │   │   │   ├── compileropt_test.go
│   │   │   │   │   ├── configuration_test.go
│   │   │   │   │   ├── debugserver_test.go
│   │   │   │   │   ├── definition_test.go
│   │   │   │   │   ├── embed_test.go
│   │   │   │   │   ├── extract_test.go
│   │   │   │   │   ├── failures_test.go
│   │   │   │   │   ├── filecache_test.go
│   │   │   │   │   ├── fix_test.go
│   │   │   │   │   ├── formatting_test.go
│   │   │   │   │   ├── generate_test.go
│   │   │   │   │   ├── highlight_test.go
│   │   │   │   │   ├── hover_test.go
│   │   │   │   │   ├── import_test.go
│   │   │   │   │   ├── imports_test.go
│   │   │   │   │   ├── link_test.go
│   │   │   │   │   ├── misc_test.go
│   │   │   │   │   ├── modify_tags_test.go
│   │   │   │   │   ├── multiple_adhoc_test.go
│   │   │   │   │   ├── package_symbols_test.go
│   │   │   │   │   ├── prompt_test.go
│   │   │   │   │   ├── references_test.go
│   │   │   │   │   ├── rename_test.go
│   │   │   │   │   ├── semantictokens_test.go
│   │   │   │   │   ├── settings_test.go
│   │   │   │   │   ├── shared_test.go
│   │   │   │   │   ├── signature_help_test.go
│   │   │   │   │   ├── staticcheck_test.go
│   │   │   │   │   ├── test_test.go
│   │   │   │   │   ├── vendor_test.go
│   │   │   │   │   ├── vuln_test.go
│   │   │   │   │   └── workspace_symbol_test.go
│   │   │   │   ├── modfile/
│   │   │   │   │   ├── modfile_test.go
│   │   │   │   │   └── tempmodfile_test.go
│   │   │   │   ├── options.go
│   │   │   │   ├── regtest.go
│   │   │   │   ├── runner.go
│   │   │   │   ├── template/
│   │   │   │   │   └── template_test.go
│   │   │   │   ├── watch/
│   │   │   │   │   ├── setting_test.go
│   │   │   │   │   └── watch_test.go
│   │   │   │   ├── web/
│   │   │   │   │   ├── assembly_test.go
│   │   │   │   │   ├── flight_test.go
│   │   │   │   │   ├── freesymbols_test.go
│   │   │   │   │   ├── pkdoc_test.go
│   │   │   │   │   ├── splitpkg_test.go
│   │   │   │   │   └── util_test.go
│   │   │   │   ├── workspace/
│   │   │   │   │   ├── adhoc_test.go
│   │   │   │   │   ├── broken_test.go
│   │   │   │   │   ├── didcreatefiles_test.go
│   │   │   │   │   ├── directoryfilters_test.go
│   │   │   │   │   ├── fromenv_test.go
│   │   │   │   │   ├── goversion_test.go
│   │   │   │   │   ├── metadata_test.go
│   │   │   │   │   ├── misspelling_test.go
│   │   │   │   │   ├── modules_test.go
│   │   │   │   │   ├── multi_folder_test.go
│   │   │   │   │   ├── packages_test.go
│   │   │   │   │   ├── quickfix_test.go
│   │   │   │   │   ├── standalone_test.go
│   │   │   │   │   ├── std_test.go
│   │   │   │   │   ├── vendor_test.go
│   │   │   │   │   ├── workspace_test.go
│   │   │   │   │   └── zero_config_test.go
│   │   │   │   └── wrappers.go
│   │   │   └── marker/
│   │   │       ├── doc.go
│   │   │       ├── marker_test.go
│   │   │       └── testdata/
│   │   │           ├── callhierarchy/
│   │   │           │   ├── callhierarchy.txt
│   │   │           │   ├── issue64451.txt
│   │   │           │   ├── issue66923.txt
│   │   │           │   └── issue75230.txt
│   │   │           ├── codeaction/
│   │   │           │   ├── add_struct_tags.txt
│   │   │           │   ├── addtest.txt
│   │   │           │   ├── change_quote.txt
│   │   │           │   ├── eliminate_dot_import.txt
│   │   │           │   ├── extract-variadic-63287.txt
│   │   │           │   ├── extract_anonymous_struct.txt
│   │   │           │   ├── extract_control.txt
│   │   │           │   ├── extract_control_label.txt
│   │   │           │   ├── extract_method.txt
│   │   │           │   ├── extract_return_err.txt
│   │   │           │   ├── extract_variable-67905.txt
│   │   │           │   ├── extract_variable-70563.txt
│   │   │           │   ├── extract_variable-if.txt
│   │   │           │   ├── extract_variable-inexact.txt
│   │   │           │   ├── extract_variable-toplevel.txt
│   │   │           │   ├── extract_variable.txt
│   │   │           │   ├── extract_variable_all.txt
│   │   │           │   ├── extract_variable_all_resolve.txt
│   │   │           │   ├── extract_variable_resolve.txt
│   │   │           │   ├── extracttofile.txt
│   │   │           │   ├── failedresolve.txt
│   │   │           │   ├── fill_struct.txt
│   │   │           │   ├── fill_struct_resolve.txt
│   │   │           │   ├── fill_switch.txt
│   │   │           │   ├── fill_switch_resolve.txt
│   │   │           │   ├── functionextraction.txt
│   │   │           │   ├── functionextraction_issue44813.txt
│   │   │           │   ├── functionextraction_issue50851.txt
│   │   │           │   ├── functionextraction_issue66289.txt
│   │   │           │   ├── functionextraction_issue73972.txt
│   │   │           │   ├── grouplines.txt
│   │   │           │   ├── import-shadows-builtin.txt
│   │   │           │   ├── imports-generated.txt
│   │   │           │   ├── imports.txt
│   │   │           │   ├── inline-lhs-var-method.txt
│   │   │           │   ├── inline-lhs-var.txt
│   │   │           │   ├── inline-var-74347.txt
│   │   │           │   ├── inline-var-74347b.txt
│   │   │           │   ├── inline-var-76144.txt
│   │   │           │   ├── inline-var-parens.txt
│   │   │           │   ├── inline-var.txt
│   │   │           │   ├── inline-version.txt
│   │   │           │   ├── inline.txt
│   │   │           │   ├── inline_issue67336.txt
│   │   │           │   ├── inline_issue68554.txt
│   │   │           │   ├── inline_resolve.txt
│   │   │           │   ├── invertif.txt
│   │   │           │   ├── issue64558.txt
│   │   │           │   ├── issue70268.txt
│   │   │           │   ├── moveparam.txt
│   │   │           │   ├── moveparam_issue70599.txt
│   │   │           │   ├── remove_struct_tags.txt
│   │   │           │   ├── removeparam.txt
│   │   │           │   ├── removeparam_formatting.txt
│   │   │           │   ├── removeparam_funcvalue.txt
│   │   │           │   ├── removeparam_imports.txt
│   │   │           │   ├── removeparam_issue65217.txt
│   │   │           │   ├── removeparam_method.txt
│   │   │           │   ├── removeparam_resolve.txt
│   │   │           │   ├── removeparam_satisfies.txt
│   │   │           │   ├── removeparam_witherrs.txt
│   │   │           │   ├── splitlines-variadic.txt
│   │   │           │   └── splitlines.txt
│   │   │           ├── codelens/
│   │   │           │   ├── generate.txt
│   │   │           │   └── test.txt
│   │   │           ├── completion/
│   │   │           │   ├── address.txt
│   │   │           │   ├── alias.txt
│   │   │           │   ├── anon.txt
│   │   │           │   ├── append.txt
│   │   │           │   ├── assign.txt
│   │   │           │   ├── bad.txt
│   │   │           │   ├── basic_lit.txt
│   │   │           │   ├── builtins.txt
│   │   │           │   ├── casesensitive.txt
│   │   │           │   ├── cast.txt
│   │   │           │   ├── channel.txt
│   │   │           │   ├── comment.txt
│   │   │           │   ├── complit.txt
│   │   │           │   ├── constant.txt
│   │   │           │   ├── danglingstmt.txt
│   │   │           │   ├── deep.txt
│   │   │           │   ├── deep2.txt
│   │   │           │   ├── errors.txt
│   │   │           │   ├── field_list.txt
│   │   │           │   ├── foobarbaz.txt
│   │   │           │   ├── func_rank.txt
│   │   │           │   ├── func_sig.txt
│   │   │           │   ├── func_snippets.txt
│   │   │           │   ├── func_value.txt
│   │   │           │   ├── fuzzy.txt
│   │   │           │   ├── imported-std.txt
│   │   │           │   ├── index.txt
│   │   │           │   ├── interfacerank.txt
│   │   │           │   ├── issue51783.txt
│   │   │           │   ├── issue56505.txt
│   │   │           │   ├── issue59096.txt
│   │   │           │   ├── issue60545.txt
│   │   │           │   ├── issue62141.txt
│   │   │           │   ├── issue62560.txt
│   │   │           │   ├── issue62676.txt
│   │   │           │   ├── issue70636.txt
│   │   │           │   ├── issue72753.txt
│   │   │           │   ├── keywords.txt
│   │   │           │   ├── labels.txt
│   │   │           │   ├── lit.txt
│   │   │           │   ├── maps.txt
│   │   │           │   ├── multi_return.txt
│   │   │           │   ├── nested_complit.txt
│   │   │           │   ├── postfix.txt
│   │   │           │   ├── postfix_placeholder.txt
│   │   │           │   ├── printf.txt
│   │   │           │   ├── randv2.txt
│   │   │           │   ├── range_func.txt
│   │   │           │   ├── rank.txt
│   │   │           │   ├── snippet.txt
│   │   │           │   ├── snippet_placeholder.txt
│   │   │           │   ├── statements.txt
│   │   │           │   ├── testy.txt
│   │   │           │   ├── type_assert.txt
│   │   │           │   ├── type_mods.txt
│   │   │           │   ├── type_params.txt
│   │   │           │   ├── type_params_reverse_infer.txt
│   │   │           │   ├── unimported-std.txt
│   │   │           │   ├── unimported.txt
│   │   │           │   ├── unresolved.txt
│   │   │           │   ├── unsafe.txt
│   │   │           │   └── variadic.txt
│   │   │           ├── configuration/
│   │   │           │   └── static.txt
│   │   │           ├── definition/
│   │   │           │   ├── asm.txt
│   │   │           │   ├── branch.txt
│   │   │           │   ├── branch_issue73797.txt
│   │   │           │   ├── branch_issue73797_go124.txt
│   │   │           │   ├── cgo.txt
│   │   │           │   ├── comment.txt
│   │   │           │   ├── embed.txt
│   │   │           │   ├── import.txt
│   │   │           │   ├── misc.txt
│   │   │           │   ├── nearby.txt
│   │   │           │   ├── return.txt
│   │   │           │   ├── standalone.txt
│   │   │           │   └── standalone_issue64557.txt
│   │   │           ├── diagnostics/
│   │   │           │   ├── addgowork.txt
│   │   │           │   ├── analyzers.txt
│   │   │           │   ├── excludedfile.txt
│   │   │           │   ├── generated.txt
│   │   │           │   ├── initcycle.txt
│   │   │           │   ├── issue56943.txt
│   │   │           │   ├── issue59005.txt
│   │   │           │   ├── issue60544.txt
│   │   │           │   ├── issue60605.txt
│   │   │           │   ├── issue64547.txt
│   │   │           │   ├── issue67360.txt
│   │   │           │   ├── issue69505.txt
│   │   │           │   ├── issue70791.txt
│   │   │           │   ├── issue71812.txt
│   │   │           │   ├── osarch_suffix.txt
│   │   │           │   ├── parseerr.txt
│   │   │           │   ├── rundespiteerrors.txt
│   │   │           │   ├── stdversion.txt
│   │   │           │   ├── stdversion_synctest.txt
│   │   │           │   ├── strangefiles.txt
│   │   │           │   ├── typeerr.txt
│   │   │           │   ├── useinternal.txt
│   │   │           │   └── usemodule.txt
│   │   │           ├── fixedbugs/
│   │   │           │   ├── issue59318.txt
│   │   │           │   ├── issue59944.txt
│   │   │           │   ├── issue61543.txt
│   │   │           │   ├── issue66109.txt
│   │   │           │   ├── issue66250.txt
│   │   │           │   ├── issue66876.txt
│   │   │           │   ├── issue71044.txt
│   │   │           │   └── issue74581.txt
│   │   │           ├── foldingrange/
│   │   │           │   ├── a.txt
│   │   │           │   ├── a_lineonly.txt
│   │   │           │   ├── bad.txt
│   │   │           │   └── parse_errors.txt
│   │   │           ├── format/
│   │   │           │   ├── format.txt
│   │   │           │   ├── generated.txt
│   │   │           │   ├── issue59554.txt
│   │   │           │   └── noparse.txt
│   │   │           ├── highlight/
│   │   │           │   ├── controlflow.txt
│   │   │           │   ├── highlight.txt
│   │   │           │   ├── highlight_kind.txt
│   │   │           │   ├── highlight_printf.txt
│   │   │           │   ├── issue60435.txt
│   │   │           │   ├── issue68918.txt
│   │   │           │   └── switchbreak.txt
│   │   │           ├── hover/
│   │   │           │   ├── basiclit.txt
│   │   │           │   ├── comment.txt
│   │   │           │   ├── const.txt
│   │   │           │   ├── embed.txt
│   │   │           │   ├── expression.txt
│   │   │           │   ├── fileuri.txt
│   │   │           │   ├── generics.txt
│   │   │           │   ├── godef.txt
│   │   │           │   ├── goprivate.txt
│   │   │           │   ├── hover-74351.txt
│   │   │           │   ├── hover.txt
│   │   │           │   ├── hover_alias.txt
│   │   │           │   ├── issue74361.txt
│   │   │           │   ├── issue75975.txt
│   │   │           │   ├── issues.txt
│   │   │           │   ├── json.txt
│   │   │           │   ├── linkable.txt
│   │   │           │   ├── linkable_generics.txt
│   │   │           │   ├── linkname.txt
│   │   │           │   ├── methods.txt
│   │   │           │   ├── pointerdoclink.txt
│   │   │           │   ├── return.txt
│   │   │           │   ├── sizeoffset.txt
│   │   │           │   ├── std.txt
│   │   │           │   └── structfield.txt
│   │   │           ├── implementation/
│   │   │           │   ├── basic.txt
│   │   │           │   ├── generics-basicalias.txt
│   │   │           │   ├── generics.txt
│   │   │           │   ├── issue43655.txt
│   │   │           │   ├── issue67041.txt
│   │   │           │   ├── issue68641.txt
│   │   │           │   ├── issue74305.txt
│   │   │           │   └── signature.txt
│   │   │           ├── inlayhints/
│   │   │           │   ├── ignored-error.txt
│   │   │           │   ├── inlayhints.txt
│   │   │           │   └── issue67142.txt
│   │   │           ├── links/
│   │   │           │   └── links.txt
│   │   │           ├── mcptools/
│   │   │           │   ├── context.txt
│   │   │           │   ├── file_context.txt
│   │   │           │   ├── file_diagnostics.txt
│   │   │           │   ├── file_metadata.txt
│   │   │           │   ├── package_api.txt
│   │   │           │   ├── references.txt
│   │   │           │   ├── rename_symbol.txt
│   │   │           │   ├── search.txt
│   │   │           │   ├── symbol_references.txt
│   │   │           │   ├── workspace.txt
│   │   │           │   ├── workspace_diagnostics.txt
│   │   │           │   └── workspace_diagnostics_empty.txt
│   │   │           ├── modfile/
│   │   │           │   ├── godebug.txt
│   │   │           │   └── godebug_bad.txt
│   │   │           ├── quickfix/
│   │   │           │   ├── embeddirective.txt
│   │   │           │   ├── infertypeargs.txt
│   │   │           │   ├── issue65024.txt
│   │   │           │   ├── noresultvalues.txt
│   │   │           │   ├── self_assignment.txt
│   │   │           │   ├── stub.txt
│   │   │           │   ├── stubmethods/
│   │   │           │   │   ├── basic.txt
│   │   │           │   │   ├── basic_resolve.txt
│   │   │           │   │   ├── fromcall_basic.txt
│   │   │           │   │   ├── fromcall_params.txt
│   │   │           │   │   ├── fromcall_returns.txt
│   │   │           │   │   ├── issue61693.txt
│   │   │           │   │   ├── issue61830.txt
│   │   │           │   │   ├── issue64078.txt
│   │   │           │   │   ├── issue64114.txt
│   │   │           │   │   ├── shadowedmethods.txt
│   │   │           │   │   └── stuberrors.txt
│   │   │           │   ├── undeclared/
│   │   │           │   │   ├── diag.txt
│   │   │           │   │   ├── missingfunction.txt
│   │   │           │   │   ├── undeclared_variable.txt
│   │   │           │   │   └── undeclaredfunc.txt
│   │   │           │   ├── unusedrequire.txt
│   │   │           │   └── unusedrequire_gowork.txt
│   │   │           ├── references/
│   │   │           │   ├── crosspackage.txt
│   │   │           │   ├── imports.txt
│   │   │           │   ├── interfaces.txt
│   │   │           │   ├── intrapackage.txt
│   │   │           │   ├── issue58506.txt
│   │   │           │   ├── issue59851.txt
│   │   │           │   ├── issue60369.txt
│   │   │           │   ├── issue60622.txt
│   │   │           │   ├── issue60676.txt
│   │   │           │   ├── issue61618.txt
│   │   │           │   ├── issue67978.txt
│   │   │           │   ├── issue75810.txt
│   │   │           │   ├── issue75810A.txt
│   │   │           │   ├── issue76872.txt
│   │   │           │   ├── shadow.txt
│   │   │           │   ├── test.txt
│   │   │           │   └── typeswitch.txt
│   │   │           ├── rename/
│   │   │           │   ├── bad.txt
│   │   │           │   ├── basic.txt
│   │   │           │   ├── conflict.txt
│   │   │           │   ├── crosspkg.txt
│   │   │           │   ├── doclink.txt
│   │   │           │   ├── embed.txt
│   │   │           │   ├── func.txt
│   │   │           │   ├── generics.txt
│   │   │           │   ├── generics_basic.txt
│   │   │           │   ├── issue39614.txt
│   │   │           │   ├── issue42134.txt
│   │   │           │   ├── issue42301.txt
│   │   │           │   ├── issue43616.txt
│   │   │           │   ├── issue57479.txt
│   │   │           │   ├── issue60752.txt
│   │   │           │   ├── issue60789.txt
│   │   │           │   ├── issue61294.txt
│   │   │           │   ├── issue61640.txt
│   │   │           │   ├── issue61813.txt
│   │   │           │   ├── issue65098.txt
│   │   │           │   ├── issue67069.txt
│   │   │           │   ├── issue70968.txt
│   │   │           │   ├── methods.txt
│   │   │           │   ├── packagedecl.txt
│   │   │           │   ├── pkgpath.txt
│   │   │           │   ├── prepare.txt
│   │   │           │   ├── prepare_func.txt
│   │   │           │   ├── prepare_move.txt
│   │   │           │   ├── random.txt
│   │   │           │   ├── recv.txt
│   │   │           │   ├── shadow.txt
│   │   │           │   ├── testy.txt
│   │   │           │   ├── typeswitch.txt
│   │   │           │   └── unexported.txt
│   │   │           ├── selectionrange/
│   │   │           │   └── selectionrange.txt
│   │   │           ├── signature/
│   │   │           │   ├── generic.txt
│   │   │           │   ├── issue63804.txt
│   │   │           │   ├── issue69552.txt
│   │   │           │   └── signature.txt
│   │   │           ├── symbol/
│   │   │           │   ├── basic.txt
│   │   │           │   └── generic.txt
│   │   │           ├── token/
│   │   │           │   ├── comment.txt
│   │   │           │   ├── format.txt
│   │   │           │   ├── illformed.txt
│   │   │           │   ├── issue66809.txt
│   │   │           │   ├── issue70251.txt
│   │   │           │   ├── modifiers.txt
│   │   │           │   └── range.txt
│   │   │           ├── typedef/
│   │   │           │   ├── expression.txt
│   │   │           │   ├── issue60544.txt
│   │   │           │   └── typedef.txt
│   │   │           ├── typehierarchy/
│   │   │           │   └── basic.txt
│   │   │           ├── workfile/
│   │   │           │   ├── godebug.txt
│   │   │           │   └── godebug_bad.txt
│   │   │           ├── workspacesymbol/
│   │   │           │   ├── allscope.txt
│   │   │           │   ├── caseinsensitive.txt
│   │   │           │   ├── casesensitive.txt
│   │   │           │   ├── issue44806.txt
│   │   │           │   ├── workspacesymbol.txt
│   │   │           │   └── wsscope.txt
│   │   │           └── zeroconfig/
│   │   │               ├── adhoc.txt
│   │   │               ├── dynamicports.txt
│   │   │               ├── nested.txt
│   │   │               └── nonworkspacemodule.txt
│   │   ├── util/
│   │   │   ├── README.md
│   │   │   ├── asm/
│   │   │   │   ├── parse.go
│   │   │   │   └── parse_test.go
│   │   │   ├── browser/
│   │   │   │   ├── README.md
│   │   │   │   └── browser.go
│   │   │   ├── bug/
│   │   │   │   ├── bug.go
│   │   │   │   └── bug_test.go
│   │   │   ├── constraints/
│   │   │   │   └── constraint.go
│   │   │   ├── cursorutil/
│   │   │   │   └── util.go
│   │   │   ├── fakenet/
│   │   │   │   └── conn.go
│   │   │   ├── fingerprint/
│   │   │   │   ├── fingerprint.go
│   │   │   │   └── fingerprint_test.go
│   │   │   ├── frob/
│   │   │   │   ├── frob.go
│   │   │   │   └── frob_test.go
│   │   │   ├── goversion/
│   │   │   │   ├── goversion.go
│   │   │   │   └── goversion_test.go
│   │   │   ├── immutable/
│   │   │   │   └── immutable.go
│   │   │   ├── lru/
│   │   │   │   ├── lru.go
│   │   │   │   ├── lru_fuzz_test.go
│   │   │   │   ├── lru_nil_test.go
│   │   │   │   └── lru_test.go
│   │   │   ├── memoize/
│   │   │   │   ├── memoize.go
│   │   │   │   └── memoize_test.go
│   │   │   ├── moremaps/
│   │   │   │   └── maps.go
│   │   │   ├── moreslices/
│   │   │   │   └── slices.go
│   │   │   ├── morestrings/
│   │   │   │   └── strings.go
│   │   │   ├── pathutil/
│   │   │   │   └── util.go
│   │   │   ├── persistent/
│   │   │   │   ├── map.go
│   │   │   │   ├── map_test.go
│   │   │   │   ├── race_test.go
│   │   │   │   ├── set.go
│   │   │   │   └── set_test.go
│   │   │   ├── safetoken/
│   │   │   │   ├── safetoken.go
│   │   │   │   └── safetoken_test.go
│   │   │   ├── tokeninternal/
│   │   │   │   └── tokeninternal.go
│   │   │   └── typesutil/
│   │   │       └── typesutil.go
│   │   ├── version/
│   │   │   └── version.go
│   │   ├── vulncheck/
│   │   │   ├── copier.go
│   │   │   ├── govulncheck/
│   │   │   │   ├── govulncheck.go
│   │   │   │   ├── handler.go
│   │   │   │   └── jsonhandler.go
│   │   │   ├── osv/
│   │   │   │   └── osv.go
│   │   │   ├── scan/
│   │   │   │   └── command.go
│   │   │   ├── semver/
│   │   │   │   ├── semver.go
│   │   │   │   └── semver_test.go
│   │   │   ├── types.go
│   │   │   └── vulntest/
│   │   │       ├── db.go
│   │   │       ├── db_test.go
│   │   │       ├── report.go
│   │   │       ├── report_test.go
│   │   │       ├── stdlib.go
│   │   │       ├── stdlib_test.go
│   │   │       └── testdata/
│   │   │           ├── GO-2020-0001.json
│   │   │           └── report.yaml
│   │   └── work/
│   │       ├── completion.go
│   │       ├── diagnostics.go
│   │       ├── format.go
│   │       └── hover.go
│   └── main.go
├── imports/
│   └── forward.go
├── internal/
│   ├── aliases/
│   │   ├── aliases.go
│   │   └── aliases_test.go
│   ├── analysis/
│   │   ├── README
│   │   ├── analyzerutil/
│   │   │   ├── doc.go
│   │   │   ├── extractdoc.go
│   │   │   ├── extractdoc_test.go
│   │   │   ├── readfile.go
│   │   │   └── version.go
│   │   ├── driverutil/
│   │   │   ├── fix.go
│   │   │   ├── print.go
│   │   │   ├── readfile.go
│   │   │   ├── url.go
│   │   │   ├── url_test.go
│   │   │   └── validatefix.go
│   │   ├── generated/
│   │   │   └── generated.go
│   │   └── typeindex/
│   │       └── typeindex.go
│   ├── astutil/
│   │   ├── clone.go
│   │   ├── comment.go
│   │   ├── comment_test.go
│   │   ├── equal.go
│   │   ├── fields.go
│   │   ├── fields_test.go
│   │   ├── free/
│   │   │   ├── free.go
│   │   │   └── free_test.go
│   │   ├── purge.go
│   │   ├── purge_test.go
│   │   ├── stringlit.go
│   │   ├── stringlit_test.go
│   │   ├── unpack.go
│   │   └── util.go
│   ├── bisect/
│   │   ├── bisect.go
│   │   └── bisect_test.go
│   ├── diff/
│   │   ├── diff.go
│   │   ├── diff_test.go
│   │   ├── difftest/
│   │   │   ├── difftest.go
│   │   │   └── difftest_test.go
│   │   ├── export_test.go
│   │   ├── lcs/
│   │   │   ├── common.go
│   │   │   ├── common_test.go
│   │   │   ├── doc.go
│   │   │   ├── git.sh
│   │   │   ├── labels.go
│   │   │   ├── old.go
│   │   │   ├── old_test.go
│   │   │   └── sequence.go
│   │   ├── merge.go
│   │   ├── merge_test.go
│   │   ├── ndiff.go
│   │   └── unified.go
│   ├── diffp/
│   │   ├── diff.go
│   │   ├── diff_test.go
│   │   └── testdata/
│   │       ├── allnew.txt
│   │       ├── allold.txt
│   │       ├── basic.txt
│   │       ├── dups.txt
│   │       ├── end.txt
│   │       ├── eof.txt
│   │       ├── eof1.txt
│   │       ├── eof2.txt
│   │       ├── long.txt
│   │       ├── same.txt
│   │       ├── start.txt
│   │       └── triv.txt
│   ├── drivertest/
│   │   ├── driver.go
│   │   └── driver_test.go
│   ├── edit/
│   │   ├── edit.go
│   │   └── edit_test.go
│   ├── event/
│   │   ├── bench_test.go
│   │   ├── core/
│   │   │   ├── event.go
│   │   │   ├── export.go
│   │   │   └── fast.go
│   │   ├── doc.go
│   │   ├── event.go
│   │   ├── export/
│   │   │   ├── eventtest/
│   │   │   │   └── eventtest.go
│   │   │   ├── id.go
│   │   │   ├── labels.go
│   │   │   ├── log.go
│   │   │   ├── log_test.go
│   │   │   ├── metric/
│   │   │   │   ├── data.go
│   │   │   │   ├── exporter.go
│   │   │   │   └── info.go
│   │   │   ├── otel/
│   │   │   │   ├── common.go
│   │   │   │   ├── metrics.go
│   │   │   │   ├── metrics_test.go
│   │   │   │   ├── options.go
│   │   │   │   ├── otel.go
│   │   │   │   ├── otel_test.go
│   │   │   │   ├── otlp.go
│   │   │   │   ├── traces.go
│   │   │   │   └── traces_test.go
│   │   │   ├── printer.go
│   │   │   ├── prometheus/
│   │   │   │   └── prometheus.go
│   │   │   └── trace.go
│   │   ├── keys/
│   │   │   ├── keys.go
│   │   │   ├── standard.go
│   │   │   ├── util.go
│   │   │   └── util_test.go
│   │   └── label/
│   │       ├── label.go
│   │       └── label_test.go
│   ├── expect/
│   │   ├── expect.go
│   │   ├── expect_test.go
│   │   ├── extract.go
│   │   └── testdata/
│   │       ├── go.fake.mod
│   │       ├── go.fake.work
│   │       └── test.go
│   ├── facts/
│   │   ├── facts.go
│   │   ├── facts_test.go
│   │   └── imports.go
│   ├── fmtstr/
│   │   ├── main.go
│   │   └── parse.go
│   ├── gcimporter/
│   │   ├── bexport_test.go
│   │   ├── bimport.go
│   │   ├── exportdata.go
│   │   ├── gcimporter.go
│   │   ├── gcimporter_test.go
│   │   ├── iexport.go
│   │   ├── iexport_common_test.go
│   │   ├── iexport_go118_test.go
│   │   ├── iexport_test.go
│   │   ├── iimport.go
│   │   ├── israce_test.go
│   │   ├── main.go
│   │   ├── predeclared.go
│   │   ├── shallow_test.go
│   │   ├── stdlib_test.go
│   │   ├── support.go
│   │   ├── testdata/
│   │   │   ├── a/
│   │   │   │   └── a.go
│   │   │   ├── a.go
│   │   │   ├── aliases/
│   │   │   │   ├── a/
│   │   │   │   │   └── a.go
│   │   │   │   ├── b/
│   │   │   │   │   └── b.go
│   │   │   │   └── c/
│   │   │   │       └── c.go
│   │   │   ├── b.go
│   │   │   ├── exports.go
│   │   │   ├── issue15920.go
│   │   │   ├── issue20046.go
│   │   │   ├── issue25301.go
│   │   │   ├── issue51836/
│   │   │   │   ├── a/
│   │   │   │   │   └── a.go
│   │   │   │   ├── a.go
│   │   │   │   └── aa.go
│   │   │   ├── issue57015.go
│   │   │   ├── issue58296/
│   │   │   │   ├── a/
│   │   │   │   │   └── a.go
│   │   │   │   ├── b/
│   │   │   │   │   └── b.go
│   │   │   │   └── c/
│   │   │   │       └── c.go
│   │   │   ├── p.go
│   │   │   └── versions/
│   │   │       ├── test.go
│   │   │       └── test_go1.20_u.a
│   │   └── ureader_yes.go
│   ├── gocommand/
│   │   ├── invoke.go
│   │   ├── invoke_notunix.go
│   │   ├── invoke_test.go
│   │   ├── invoke_unix.go
│   │   ├── vendor.go
│   │   ├── version.go
│   │   └── version_test.go
│   ├── gopathwalk/
│   │   ├── walk.go
│   │   └── walk_test.go
│   ├── goplsexport/
│   │   └── export.go
│   ├── goroot/
│   │   └── importcfg.go
│   ├── imports/
│   │   ├── fix.go
│   │   ├── fix_test.go
│   │   ├── imports.go
│   │   ├── imports_test.go
│   │   ├── mkindex.go
│   │   ├── mod.go
│   │   ├── mod_cache.go
│   │   ├── mod_cache_test.go
│   │   ├── mod_test.go
│   │   ├── sortimports.go
│   │   ├── source.go
│   │   ├── source_env.go
│   │   ├── source_modindex.go
│   │   ├── sourcex_test.go
│   │   └── testdata/
│   │       └── mod/
│   │           ├── example.com_v1.0.0.txt
│   │           ├── golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt
│   │           ├── rsc.io_!q!u!o!t!e_v1.5.2.txt
│   │           ├── rsc.io_!q!u!o!t!e_v1.5.3-!p!r!e.txt
│   │           ├── rsc.io_quote_v1.5.1.txt
│   │           ├── rsc.io_quote_v1.5.2.txt
│   │           ├── rsc.io_quote_v2_v2.0.1.txt
│   │           ├── rsc.io_quote_v3_v3.0.0.txt
│   │           ├── rsc.io_sampler_v1.3.0.txt
│   │           └── rsc.io_sampler_v1.3.1.txt
│   ├── jsonrpc2/
│   │   ├── conn.go
│   │   ├── handler.go
│   │   ├── jsonrpc2.go
│   │   ├── jsonrpc2_test.go
│   │   ├── labels.go
│   │   ├── messages.go
│   │   ├── serve.go
│   │   ├── serve_test.go
│   │   ├── servertest/
│   │   │   ├── servertest.go
│   │   │   └── servertest_test.go
│   │   ├── stack/
│   │   │   ├── parse.go
│   │   │   ├── process.go
│   │   │   ├── stack.go
│   │   │   ├── stack_test.go
│   │   │   └── stacktest/
│   │   │       └── stacktest.go
│   │   ├── stream.go
│   │   ├── wire.go
│   │   └── wire_test.go
│   ├── jsonrpc2_v2/
│   │   ├── conn.go
│   │   ├── frame.go
│   │   ├── jsonrpc2.go
│   │   ├── jsonrpc2_test.go
│   │   ├── messages.go
│   │   ├── net.go
│   │   ├── serve.go
│   │   ├── serve_test.go
│   │   ├── wire.go
│   │   └── wire_test.go
│   ├── mcp/
│   │   ├── CONTRIBUTING.md
│   │   ├── README.md
│   │   ├── client.go
│   │   ├── client_list_test.go
│   │   ├── client_test.go
│   │   ├── cmd.go
│   │   ├── cmd_test.go
│   │   ├── conformance_go124_test.go
│   │   ├── conformance_go125_test.go
│   │   ├── conformance_test.go
│   │   ├── content.go
│   │   ├── content_test.go
│   │   ├── create-repo.sh
│   │   ├── design/
│   │   │   └── design.md
│   │   ├── example_progress_test.go
│   │   ├── examples/
│   │   │   ├── hello/
│   │   │   │   └── main.go
│   │   │   └── sse/
│   │   │       └── main.go
│   │   ├── features.go
│   │   ├── features_test.go
│   │   ├── generate.go
│   │   ├── internal/
│   │   │   ├── oauthex/
│   │   │   │   ├── oauth2.go
│   │   │   │   ├── oauth2_test.go
│   │   │   │   └── resource_meta.go
│   │   │   ├── readme/
│   │   │   │   ├── Makefile
│   │   │   │   ├── README.src.md
│   │   │   │   ├── build.sh
│   │   │   │   ├── client/
│   │   │   │   │   └── client.go
│   │   │   │   └── server/
│   │   │   │       └── server.go
│   │   │   └── util/
│   │   │       ├── util.go
│   │   │       └── util_test.go
│   │   ├── jsonschema/
│   │   │   ├── annotations.go
│   │   │   ├── doc.go
│   │   │   ├── infer.go
│   │   │   ├── infer_test.go
│   │   │   ├── json_pointer.go
│   │   │   ├── json_pointer_test.go
│   │   │   ├── meta-schemas/
│   │   │   │   └── draft2020-12/
│   │   │   │       ├── meta/
│   │   │   │       │   ├── applicator.json
│   │   │   │       │   ├── content.json
│   │   │   │       │   ├── core.json
│   │   │   │       │   ├── format-annotation.json
│   │   │   │       │   ├── meta-data.json
│   │   │   │       │   ├── unevaluated.json
│   │   │   │       │   └── validation.json
│   │   │   │       └── schema.json
│   │   │   ├── resolve.go
│   │   │   ├── resolve_test.go
│   │   │   ├── schema.go
│   │   │   ├── schema_test.go
│   │   │   ├── testdata/
│   │   │   │   ├── draft2020-12/
│   │   │   │   │   ├── README.md
│   │   │   │   │   ├── additionalProperties.json
│   │   │   │   │   ├── allOf.json
│   │   │   │   │   ├── anchor.json
│   │   │   │   │   ├── anyOf.json
│   │   │   │   │   ├── boolean_schema.json
│   │   │   │   │   ├── const.json
│   │   │   │   │   ├── contains.json
│   │   │   │   │   ├── default.json
│   │   │   │   │   ├── defs.json
│   │   │   │   │   ├── dependentRequired.json
│   │   │   │   │   ├── dependentSchemas.json
│   │   │   │   │   ├── dynamicRef.json
│   │   │   │   │   ├── enum.json
│   │   │   │   │   ├── exclusiveMaximum.json
│   │   │   │   │   ├── exclusiveMinimum.json
│   │   │   │   │   ├── if-then-else.json
│   │   │   │   │   ├── infinite-loop-detection.json
│   │   │   │   │   ├── items.json
│   │   │   │   │   ├── maxContains.json
│   │   │   │   │   ├── maxItems.json
│   │   │   │   │   ├── maxLength.json
│   │   │   │   │   ├── maxProperties.json
│   │   │   │   │   ├── maximum.json
│   │   │   │   │   ├── minContains.json
│   │   │   │   │   ├── minItems.json
│   │   │   │   │   ├── minLength.json
│   │   │   │   │   ├── minProperties.json
│   │   │   │   │   ├── minimum.json
│   │   │   │   │   ├── multipleOf.json
│   │   │   │   │   ├── not.json
│   │   │   │   │   ├── oneOf.json
│   │   │   │   │   ├── pattern.json
│   │   │   │   │   ├── patternProperties.json
│   │   │   │   │   ├── prefixItems.json
│   │   │   │   │   ├── properties.json
│   │   │   │   │   ├── propertyNames.json
│   │   │   │   │   ├── ref.json
│   │   │   │   │   ├── refRemote.json
│   │   │   │   │   ├── required.json
│   │   │   │   │   ├── type.json
│   │   │   │   │   ├── unevaluatedItems.json
│   │   │   │   │   ├── unevaluatedProperties.json
│   │   │   │   │   └── uniqueItems.json
│   │   │   │   └── remotes/
│   │   │   │       ├── README.md
│   │   │   │       ├── different-id-ref-string.json
│   │   │   │       ├── draft2020-12/
│   │   │   │       │   ├── baseUriChange/
│   │   │   │       │   │   └── folderInteger.json
│   │   │   │       │   ├── baseUriChangeFolder/
│   │   │   │       │   │   └── folderInteger.json
│   │   │   │       │   ├── baseUriChangeFolderInSubschema/
│   │   │   │       │   │   └── folderInteger.json
│   │   │   │       │   ├── detached-dynamicref.json
│   │   │   │       │   ├── detached-ref.json
│   │   │   │       │   ├── extendible-dynamic-ref.json
│   │   │   │       │   ├── format-assertion-false.json
│   │   │   │       │   ├── format-assertion-true.json
│   │   │   │       │   ├── integer.json
│   │   │   │       │   ├── locationIndependentIdentifier.json
│   │   │   │       │   ├── metaschema-no-validation.json
│   │   │   │       │   ├── metaschema-optional-vocabulary.json
│   │   │   │       │   ├── name-defs.json
│   │   │   │       │   ├── nested/
│   │   │   │       │   │   ├── foo-ref-string.json
│   │   │   │       │   │   └── string.json
│   │   │   │       │   ├── prefixItems.json
│   │   │   │       │   ├── ref-and-defs.json
│   │   │   │       │   ├── subSchemas.json
│   │   │   │       │   └── tree.json
│   │   │   │       ├── nested-absolute-ref-to-string.json
│   │   │   │       └── urn-ref-string.json
│   │   │   ├── util.go
│   │   │   ├── util_test.go
│   │   │   ├── validate.go
│   │   │   └── validate_test.go
│   │   ├── logging.go
│   │   ├── mcp-repo-replace.txt
│   │   ├── mcp.go
│   │   ├── mcp_test.go
│   │   ├── prompt.go
│   │   ├── protocol.go
│   │   ├── resource.go
│   │   ├── resource_test.go
│   │   ├── root.go
│   │   ├── server.go
│   │   ├── server_example_test.go
│   │   ├── server_test.go
│   │   ├── shared.go
│   │   ├── shared_test.go
│   │   ├── sse.go
│   │   ├── sse_example_test.go
│   │   ├── sse_test.go
│   │   ├── streamable.go
│   │   ├── streamable_test.go
│   │   ├── testdata/
│   │   │   ├── conformance/
│   │   │   │   └── server/
│   │   │   │       ├── prompts.txtar
│   │   │   │       ├── resources.txtar
│   │   │   │       ├── tools.txtar
│   │   │   │       ├── version-latest.txtar
│   │   │   │       └── version-older.txtar
│   │   │   ├── files/
│   │   │   │   ├── info.txt
│   │   │   │   └── template.txt
│   │   │   ├── private.txt
│   │   │   └── public/
│   │   │       ├── dir/
│   │   │       │   └── file3.txt
│   │   │       ├── file1.txt
│   │   │       └── file2.txt
│   │   ├── tool.go
│   │   ├── tool_test.go
│   │   ├── transport.go
│   │   ├── transport_test.go
│   │   ├── util.go
│   │   └── util_test.go
│   ├── modindex/
│   │   ├── dir_test.go
│   │   ├── directories.go
│   │   ├── export_test.go
│   │   ├── gomodindex/
│   │   │   └── cmd.go
│   │   ├── index.go
│   │   ├── lookup.go
│   │   ├── lookup_test.go
│   │   ├── modindex.go
│   │   └── symbols.go
│   ├── moreiters/
│   │   └── iters.go
│   ├── packagepath/
│   │   ├── packagepath.go
│   │   └── packagepath_test.go
│   ├── packagesinternal/
│   │   └── packages.go
│   ├── packagestest/
│   │   ├── expect.go
│   │   ├── expect_test.go
│   │   ├── export.go
│   │   ├── export_test.go
│   │   ├── gopath.go
│   │   ├── gopath_test.go
│   │   ├── modules.go
│   │   ├── modules_test.go
│   │   └── testdata/
│   │       ├── groups/
│   │       │   ├── one/
│   │       │   │   ├── modules/
│   │       │   │   │   └── example.com/
│   │       │   │   │       └── extra/
│   │       │   │   │           └── help.go
│   │       │   │   └── primarymod/
│   │       │   │       └── main.go
│   │       │   └── two/
│   │       │       ├── modules/
│   │       │       │   └── example.com/
│   │       │       │       ├── extra/
│   │       │       │       │   ├── geez/
│   │       │       │       │   │   └── help.go
│   │       │       │       │   ├── v2/
│   │       │       │       │   │   ├── geez/
│   │       │       │       │   │   │   └── help.go
│   │       │       │       │   │   └── me.go
│   │       │       │       │   └── yo.go
│   │       │       │       ├── tempmod/
│   │       │       │       │   └── main.go
│   │       │       │       ├── what@v1.0.0/
│   │       │       │       │   └── main.go
│   │       │       │       └── what@v1.1.0/
│   │       │       │           └── main.go
│   │       │       └── primarymod/
│   │       │           ├── expect/
│   │       │           │   ├── yo.go
│   │       │           │   └── yo_test.go
│   │       │           └── main.go
│   │       ├── test.go
│   │       ├── test_test.go
│   │       └── x_test.go
│   ├── pkgbits/
│   │   ├── codes.go
│   │   ├── decoder.go
│   │   ├── doc.go
│   │   ├── encoder.go
│   │   ├── flags.go
│   │   ├── pkgbits_test.go
│   │   ├── reloc.go
│   │   ├── support.go
│   │   ├── sync.go
│   │   ├── syncmarker_string.go
│   │   └── version.go
│   ├── pprof/
│   │   ├── main.go
│   │   ├── pprof.go
│   │   ├── pprof_test.go
│   │   └── testdata/
│   │       └── sample.pprof
│   ├── proxydir/
│   │   ├── proxydir.go
│   │   └── proxydir_test.go
│   ├── refactor/
│   │   ├── delete.go
│   │   ├── delete_test.go
│   │   ├── edit.go
│   │   ├── imports.go
│   │   ├── imports_test.go
│   │   ├── inline/
│   │   │   ├── callee.go
│   │   │   ├── calleefx.go
│   │   │   ├── calleefx_test.go
│   │   │   ├── doc.go
│   │   │   ├── escape.go
│   │   │   ├── everything_test.go
│   │   │   ├── export_test.go
│   │   │   ├── falcon.go
│   │   │   ├── falcon_test.go
│   │   │   ├── inline.go
│   │   │   ├── inline_test.go
│   │   │   ├── testdata/
│   │   │   │   ├── assignment-splice.txtar
│   │   │   │   ├── assignment.txtar
│   │   │   │   ├── basic-err.txtar
│   │   │   │   ├── basic-literal.txtar
│   │   │   │   ├── basic-reduce.txtar
│   │   │   │   ├── cgo.txtar
│   │   │   │   ├── comments.txtar
│   │   │   │   ├── crosspkg-selfref.txtar
│   │   │   │   ├── crosspkg.txtar
│   │   │   │   ├── dotimport.txtar
│   │   │   │   ├── embed.txtar
│   │   │   │   ├── empty-body.txtar
│   │   │   │   ├── err-basic.txtar
│   │   │   │   ├── err-shadow-builtin.txtar
│   │   │   │   ├── err-shadow-pkg.txtar
│   │   │   │   ├── err-unexported.txtar
│   │   │   │   ├── exprstmt.txtar
│   │   │   │   ├── generic.txtar
│   │   │   │   ├── import-comments.txtar
│   │   │   │   ├── import-comments2.txtar
│   │   │   │   ├── import-preserve-local-pkgname.txtar
│   │   │   │   ├── import-rename.txtar
│   │   │   │   ├── import-shadow-1.txtar
│   │   │   │   ├── import-shadow-2.txtar
│   │   │   │   ├── import-shadow.txtar
│   │   │   │   ├── internal.txtar
│   │   │   │   ├── issue62667.txtar
│   │   │   │   ├── issue63298.txtar
│   │   │   │   ├── issue69441.txtar
│   │   │   │   ├── issue69442.txtar
│   │   │   │   ├── line-directives.txtar
│   │   │   │   ├── method.txtar
│   │   │   │   ├── multistmt-body.txtar
│   │   │   │   ├── n-ary.txtar
│   │   │   │   ├── newexpr.txtar
│   │   │   │   ├── param-subst.txtar
│   │   │   │   ├── revdotimport.txtar
│   │   │   │   ├── std-internal.txtar
│   │   │   │   ├── substgroups.txtar
│   │   │   │   └── tailcall.txtar
│   │   │   └── util.go
│   │   └── refactor.go
│   ├── robustio/
│   │   ├── copyfiles.go
│   │   ├── gopls_windows.go
│   │   ├── robustio.go
│   │   ├── robustio_darwin.go
│   │   ├── robustio_flaky.go
│   │   ├── robustio_other.go
│   │   ├── robustio_plan9.go
│   │   ├── robustio_posix.go
│   │   ├── robustio_test.go
│   │   └── robustio_windows.go
│   ├── stdlib/
│   │   ├── deps.go
│   │   ├── deps_test.go
│   │   ├── generate.go
│   │   ├── import.go
│   │   ├── manifest.go
│   │   ├── stdlib.go
│   │   └── testdata/
│   │       ├── nethttp.deps
│   │       └── nethttp.imports
│   ├── testenv/
│   │   ├── exec.go
│   │   ├── testenv.go
│   │   ├── testenv_notunix.go
│   │   └── testenv_unix.go
│   ├── testfiles/
│   │   ├── testdata/
│   │   │   ├── somefile.txt
│   │   │   └── versions/
│   │   │       ├── go.mod.test
│   │   │       ├── mod.go
│   │   │       ├── post.go
│   │   │       ├── pre.go
│   │   │       └── sub.test/
│   │   │           └── sub.go.test
│   │   ├── testfiles.go
│   │   └── testfiles_test.go
│   ├── tool/
│   │   └── tool.go
│   ├── typeparams/
│   │   ├── common.go
│   │   ├── common_test.go
│   │   ├── copytermlist.go
│   │   ├── coretype.go
│   │   ├── coretype_test.go
│   │   ├── free.go
│   │   ├── free_test.go
│   │   ├── genericfeatures/
│   │   │   └── features.go
│   │   ├── normalize.go
│   │   ├── normalize_test.go
│   │   ├── termlist.go
│   │   └── typeterm.go
│   ├── typesinternal/
│   │   ├── classify_call.go
│   │   ├── classify_call_test.go
│   │   ├── element.go
│   │   ├── element_test.go
│   │   ├── errorcode.go
│   │   ├── errorcode_string.go
│   │   ├── errorcode_test.go
│   │   ├── fx.go
│   │   ├── fx_test.go
│   │   ├── isnamed.go
│   │   ├── qualifier.go
│   │   ├── recv.go
│   │   ├── toonew.go
│   │   ├── typeindex/
│   │   │   ├── typeindex.go
│   │   │   └── typeindex_test.go
│   │   ├── types.go
│   │   ├── varkind.go
│   │   ├── varkind_go124.go
│   │   ├── zerovalue.go
│   │   └── zerovalue_test.go
│   ├── versions/
│   │   ├── features.go
│   │   ├── gover.go
│   │   ├── types.go
│   │   ├── types_test.go
│   │   ├── versions.go
│   │   └── versions_test.go
│   └── xcontext/
│       └── xcontext.go
├── playground/
│   ├── playground.go
│   └── socket/
│       ├── socket.go
│       └── socket_test.go
├── present/
│   ├── args.go
│   ├── caption.go
│   ├── code.go
│   ├── code_test.go
│   ├── doc.go
│   ├── html.go
│   ├── iframe.go
│   ├── image.go
│   ├── link.go
│   ├── link_test.go
│   ├── parse.go
│   ├── parse_test.go
│   ├── style.go
│   ├── style_test.go
│   ├── testdata/
│   │   ├── README
│   │   ├── basic.md
│   │   ├── basic.p
│   │   ├── code.md
│   │   ├── code.p
│   │   ├── code.txt
│   │   ├── list.md
│   │   ├── list.p
│   │   ├── media.html
│   │   ├── media.md
│   │   ├── media.p
│   │   ├── pre.md
│   │   └── pre.p
│   └── video.go
├── refactor/
│   ├── README
│   ├── eg/
│   │   ├── eg.go
│   │   ├── eg_test.go
│   │   ├── match.go
│   │   ├── rewrite.go
│   │   └── testdata/
│   │       ├── a.txtar
│   │       ├── b.txtar
│   │       ├── bad_type.txtar
│   │       ├── c.txtar
│   │       ├── d.txtar
│   │       ├── e.txtar
│   │       ├── expr_type_mismatch.txtar
│   │       ├── f.txtar
│   │       ├── g.txtar
│   │       ├── h.txtar
│   │       ├── i.txtar
│   │       ├── j.txtar
│   │       ├── no_after_return.txtar
│   │       ├── no_before.txtar
│   │       └── type_mismatch.txtar
│   ├── importgraph/
│   │   ├── graph.go
│   │   └── graph_test.go
│   ├── rename/
│   │   ├── check.go
│   │   ├── mvpkg.go
│   │   ├── mvpkg_test.go
│   │   ├── rename.go
│   │   ├── rename_test.go
│   │   ├── spec.go
│   │   └── util.go
│   └── satisfy/
│       ├── find.go
│       └── find_test.go
└── txtar/
    ├── archive.go
    ├── archive_test.go
    ├── fs.go
    └── fs_test.go

================================================
FILE CONTENTS
================================================

================================================
FILE: .gitattributes
================================================
# Treat all files in this repo as binary, with no git magic updating
# line endings. Windows users contributing to Go will need to use a
# modern version of git and editors capable of LF line endings.
#
# We'll prevent accidental CRLF line endings from entering the repo
# via the git-review gofmt checks.
#
# See golang.org/issue/9281

* -text


================================================
FILE: .gitignore
================================================
# Add no patterns to .gitignore except for files generated by the build.
last-change


================================================
FILE: .prettierrc
================================================
{
  "singleQuote": true,
  "trailingComma": "es5"
}

================================================
FILE: CONTRIBUTING.md
================================================
# Contributing to Go

Go is an open source project.

It is the work of hundreds of contributors. We appreciate your help!

## Filing issues

When [filing an issue](https://golang.org/issue/new), make sure to answer these five questions:

1.  What version of Go are you using (`go version`)?
2.  What operating system and processor architecture are you using?
3.  What did you do?
4.  What did you expect to see?
5.  What did you see instead?

General questions should go to the [golang-nuts mailing list](https://groups.google.com/group/golang-nuts) instead of the issue tracker.
The gophers there will answer or ask you to file an issue if you've tripped over a bug.

## Contributing code

Please read the [Contribution Guidelines](https://golang.org/doc/contribute.html)
before sending patches.

Unless otherwise noted, the Go source files are distributed under
the BSD-style license found in the LICENSE file.


================================================
FILE: LICENSE
================================================
Copyright 2009 The Go Authors.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of Google LLC nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.


================================================
FILE: PATENTS
================================================
Additional IP Rights Grant (Patents)

"This implementation" means the copyrightable works distributed by
Google as part of the Go project.

Google hereby grants to You a perpetual, worldwide, non-exclusive,
no-charge, royalty-free, irrevocable (except as stated in this section)
patent license to make, have made, use, offer to sell, sell, import,
transfer and otherwise run, modify and propagate the contents of this
implementation of Go, where such license applies only to those patent
claims, both currently owned or controlled by Google and acquired in
the future, licensable by Google that are necessarily infringed by this
implementation of Go.  This grant does not include claims that would be
infringed only as a consequence of further modification of this
implementation.  If you or your agent or exclusive licensee institute or
order or agree to the institution of patent litigation against any
entity (including a cross-claim or counterclaim in a lawsuit) alleging
that this implementation of Go or any code incorporated within this
implementation of Go constitutes direct or contributory patent
infringement, or inducement of patent infringement, then any patent
rights granted to you under this License for this implementation of Go
shall terminate as of the date such litigation is filed.


================================================
FILE: README.md
================================================
# Go Tools

[![PkgGoDev](https://pkg.go.dev/badge/golang.org/x/tools)](https://pkg.go.dev/golang.org/x/tools)

This repository provides the `golang.org/x/tools` module, comprising
various tools and packages mostly for static analysis of Go programs,
some of which are listed below.
Use the "Go reference" link above for more information about any package.

It also contains the
[`golang.org/x/tools/gopls`](https://pkg.go.dev/golang.org/x/tools/gopls)
module, whose root package is a language-server protocol (LSP) server for Go.
An LSP server analyses the source code of a project and
responds to requests from a wide range of editors such as VSCode and
Vim, allowing them to support IDE-like functionality.

<!-- List only packages of general interest below. -->

Selected commands:

- `cmd/goimports` formats a Go program like `go fmt` and additionally
  inserts import statements for any packages required by the file
  after it is edited.
- `cmd/callgraph` prints the call graph of a Go program.
- `cmd/digraph` is a utility for manipulating directed graphs in textual notation.
- `cmd/stringer` generates declarations (including a `String` method) for "enum" types.
- `cmd/toolstash` is a utility to simplify working with multiple versions of the Go toolchain.

These commands may be fetched with a command such as
```
go install golang.org/x/tools/cmd/goimports@latest
```

Selected packages:

- `go/ssa` provides a static single-assignment form (SSA) intermediate
  representation (IR) for Go programs, similar to a typical compiler,
  for use by analysis tools.

- `go/packages` provides a simple interface for loading, parsing, and
  type checking a complete Go program from source code.

- `go/analysis` provides a framework for modular static analysis of Go
  programs.

- `go/callgraph` provides call graphs of Go programs using a variety
  of algorithms with different trade-offs.

- `go/ast/inspector` provides an optimized means of traversing a Go
  parse tree for use in analysis tools.

- `go/cfg` provides a simple control-flow graph (CFG) for a Go function.

- `go/gcexportdata` and `go/gccgoexportdata` read and write the binary
  files containing type information used by the standard and `gccgo` compilers.

- `go/types/objectpath` provides a stable naming scheme for named
  entities ("objects") in the `go/types` API.

Numerous other packages provide more esoteric functionality.

<!-- Some that didn't make the cut:

golang.org/x/tools/benchmark/parse
golang.org/x/tools/go/ast/astutil
golang.org/x/tools/go/types/typeutil
golang.org/x/tools/playground
golang.org/x/tools/present
golang.org/x/tools/refactor/importgraph
golang.org/x/tools/refactor/rename
golang.org/x/tools/refactor/satisfy
golang.org/x/tools/txtar

-->

## Contributing

This repository uses Gerrit for code changes.
To learn how to submit changes, see https://go.dev/doc/contribute.

The git repository is https://go.googlesource.com/tools.

The main issue tracker for the tools repository is located at
https://go.dev/issues. Prefix your issue with "x/tools/(your
subdir):" in the subject line, so it is easy to find.

### JavaScript and CSS Formatting

This repository uses [prettier](https://prettier.io/) to format JS and CSS files.

The version of `prettier` used is 1.18.2.

It is encouraged that all JS and CSS code be run through this before submitting
a change. However, it is not a strict requirement enforced by CI.


================================================
FILE: benchmark/parse/parse.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package parse provides support for parsing benchmark results as
// generated by 'go test -bench'.
package parse // import "golang.org/x/tools/benchmark/parse"

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"strconv"
	"strings"
)

// Flags used by Benchmark.Measured to indicate
// which measurements a Benchmark contains.
const (
	NsPerOp = 1 << iota
	MBPerS
	AllocedBytesPerOp
	AllocsPerOp
)

// Benchmark is one run of a single benchmark.
type Benchmark struct {
	Name              string  // benchmark name
	N                 int     // number of iterations
	NsPerOp           float64 // nanoseconds per iteration
	AllocedBytesPerOp uint64  // bytes allocated per iteration
	AllocsPerOp       uint64  // allocs per iteration
	MBPerS            float64 // MB processed per second
	Measured          int     // which measurements were recorded
	Ord               int     // ordinal position within a benchmark run
}

// ParseLine extracts a Benchmark from a single line of testing.B
// output.
func ParseLine(line string) (*Benchmark, error) {
	fields := strings.Fields(line)

	// Two required, positional fields: Name and iterations.
	if len(fields) < 2 {
		return nil, fmt.Errorf("two fields required, have %d", len(fields))
	}
	if !strings.HasPrefix(fields[0], "Benchmark") {
		return nil, fmt.Errorf(`first field does not start with "Benchmark"`)
	}
	n, err := strconv.Atoi(fields[1])
	if err != nil {
		return nil, err
	}
	b := &Benchmark{Name: fields[0], N: n}

	// Parse any remaining pairs of fields; we've parsed one pair already.
	for i := 1; i < len(fields)/2; i++ {
		b.parseMeasurement(fields[i*2], fields[i*2+1])
	}
	return b, nil
}

func (b *Benchmark) parseMeasurement(quant string, unit string) {
	switch unit {
	case "ns/op":
		if f, err := strconv.ParseFloat(quant, 64); err == nil {
			b.NsPerOp = f
			b.Measured |= NsPerOp
		}
	case "MB/s":
		if f, err := strconv.ParseFloat(quant, 64); err == nil {
			b.MBPerS = f
			b.Measured |= MBPerS
		}
	case "B/op":
		if i, err := strconv.ParseUint(quant, 10, 64); err == nil {
			b.AllocedBytesPerOp = i
			b.Measured |= AllocedBytesPerOp
		}
	case "allocs/op":
		if i, err := strconv.ParseUint(quant, 10, 64); err == nil {
			b.AllocsPerOp = i
			b.Measured |= AllocsPerOp
		}
	}
}

func (b *Benchmark) String() string {
	buf := new(bytes.Buffer)
	fmt.Fprintf(buf, "%s %d", b.Name, b.N)
	if (b.Measured & NsPerOp) != 0 {
		fmt.Fprintf(buf, " %.2f ns/op", b.NsPerOp)
	}
	if (b.Measured & MBPerS) != 0 {
		fmt.Fprintf(buf, " %.2f MB/s", b.MBPerS)
	}
	if (b.Measured & AllocedBytesPerOp) != 0 {
		fmt.Fprintf(buf, " %d B/op", b.AllocedBytesPerOp)
	}
	if (b.Measured & AllocsPerOp) != 0 {
		fmt.Fprintf(buf, " %d allocs/op", b.AllocsPerOp)
	}
	return buf.String()
}

// Set is a collection of benchmarks from one
// testing.B run, keyed by name to facilitate comparison.
type Set map[string][]*Benchmark

// ParseSet extracts a Set from testing.B output.
// ParseSet preserves the order of benchmarks that have identical
// names.
func ParseSet(r io.Reader) (Set, error) {
	bb := make(Set)
	scan := bufio.NewScanner(r)
	ord := 0
	for scan.Scan() {
		if b, err := ParseLine(scan.Text()); err == nil {
			b.Ord = ord
			ord++
			bb[b.Name] = append(bb[b.Name], b)
		}
	}

	if err := scan.Err(); err != nil {
		return nil, err
	}

	return bb, nil
}


================================================
FILE: benchmark/parse/parse_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package parse

import (
	"reflect"
	"strings"
	"testing"
)

func TestParseLine(t *testing.T) {
	cases := []struct {
		line string
		want *Benchmark
		err  bool // expect an error
	}{
		{
			line: "BenchmarkEncrypt	100000000	        19.6 ns/op",
			want: &Benchmark{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6,
				Measured: NsPerOp,
			},
		},
		{
			line: "BenchmarkEncrypt	100000000	        19.6 ns/op	 817.77 MB/s",
			want: &Benchmark{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6, MBPerS: 817.77,
				Measured: NsPerOp | MBPerS,
			},
		},
		{
			line: "BenchmarkEncrypt	100000000	        19.6 ns/op	 817.77",
			want: &Benchmark{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6,
				Measured: NsPerOp,
			},
		},
		{
			line: "BenchmarkEncrypt	100000000	        19.6 ns/op	 817.77 MB/s	       5 allocs/op",
			want: &Benchmark{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6, MBPerS: 817.77, AllocsPerOp: 5,
				Measured: NsPerOp | MBPerS | AllocsPerOp,
			},
		},
		{
			line: "BenchmarkEncrypt	100000000	        19.6 ns/op	 817.77 MB/s	       3 B/op	       5 allocs/op",
			want: &Benchmark{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6, MBPerS: 817.77, AllocedBytesPerOp: 3, AllocsPerOp: 5,
				Measured: NsPerOp | MBPerS | AllocedBytesPerOp | AllocsPerOp,
			},
		},
		// error handling cases
		{
			line: "BenchPress	100	        19.6 ns/op", // non-benchmark
			err:  true,
		},
		{
			line: "BenchmarkEncrypt	lots	        19.6 ns/op", // non-int iterations
			err:  true,
		},
		{
			line: "BenchmarkBridge	100000000	        19.6 smoots", // unknown unit
			want: &Benchmark{
				Name: "BenchmarkBridge",
				N:    100000000,
			},
		},
		{
			line: "PASS",
			err:  true,
		},
	}

	for _, tt := range cases {
		have, err := ParseLine(tt.line)
		if tt.err && err == nil {
			t.Errorf("parsing line %q should have failed", tt.line)
			continue
		}
		if !reflect.DeepEqual(have, tt.want) {
			t.Errorf("parsed line %q incorrectly, want %v have %v", tt.line, tt.want, have)
		}
	}
}

func TestParseSet(t *testing.T) {
	// Test two things:
	// 1. The noise that can accompany testing.B output gets ignored.
	// 2. Benchmarks with the same name have their order preserved.
	in := `
		?   	crypto	[no test files]
		PASS
				pem_decrypt_test.go:17: test 4. %!s(x509.PEMCipher=5)
			... [output truncated]

		BenchmarkEncrypt	100000000	        19.6 ns/op
		BenchmarkEncrypt	 5000000	       517 ns/op
		=== RUN TestChunk
		--- PASS: TestChunk (0.00 seconds)
		--- SKIP: TestLinuxSendfile (0.00 seconds)
			fs_test.go:716: skipping; linux-only test
		BenchmarkReadRequestApachebench	 1000000	      2960 ns/op	  27.70 MB/s	     839 B/op	       9 allocs/op
		BenchmarkClientServerParallel64	   50000	     59192 ns/op	    7028 B/op	      60 allocs/op
		ok  	net/http	95.783s
	`

	want := Set{
		"BenchmarkReadRequestApachebench": []*Benchmark{
			{
				Name: "BenchmarkReadRequestApachebench",
				N:    1000000, NsPerOp: 2960, MBPerS: 27.70, AllocedBytesPerOp: 839, AllocsPerOp: 9,
				Measured: NsPerOp | MBPerS | AllocedBytesPerOp | AllocsPerOp,
				Ord:      2,
			},
		},
		"BenchmarkClientServerParallel64": []*Benchmark{
			{
				Name: "BenchmarkClientServerParallel64",
				N:    50000, NsPerOp: 59192, AllocedBytesPerOp: 7028, AllocsPerOp: 60,
				Measured: NsPerOp | AllocedBytesPerOp | AllocsPerOp,
				Ord:      3,
			},
		},
		"BenchmarkEncrypt": []*Benchmark{
			{
				Name: "BenchmarkEncrypt",
				N:    100000000, NsPerOp: 19.6,
				Measured: NsPerOp,
				Ord:      0,
			},
			{
				Name: "BenchmarkEncrypt",
				N:    5000000, NsPerOp: 517,
				Measured: NsPerOp,
				Ord:      1,
			},
		},
	}

	have, err := ParseSet(strings.NewReader(in))
	if err != nil {
		t.Fatalf("unexpected err during ParseSet: %v", err)
	}
	if !reflect.DeepEqual(want, have) {
		t.Errorf("parsed bench set incorrectly, want %v have %v", want, have)
	}
}

func TestString(t *testing.T) {
	tests := []struct {
		name   string
		input  *Benchmark
		wanted string
	}{
		{
			name: "nsTest",
			input: &Benchmark{
				Name: "BenchmarkTest",
				N:    100000000, NsPerOp: 19.6,
				Measured: NsPerOp,
			},
			wanted: "BenchmarkTest 100000000 19.60 ns/op",
		},
		{
			name: "mbTest",
			input: &Benchmark{
				Name: "BenchmarkTest",
				N:    100000000, MBPerS: 19.6,
				Measured: MBPerS,
			},
			wanted: "BenchmarkTest 100000000 19.60 MB/s",
		},
		{
			name: "allocatedBytesTest",
			input: &Benchmark{
				Name: "BenchmarkTest",
				N:    100000000, AllocedBytesPerOp: 5,
				Measured: AllocedBytesPerOp,
			},
			wanted: "BenchmarkTest 100000000 5 B/op",
		},
		{
			name: "allocsTest",
			input: &Benchmark{
				Name: "BenchmarkTest",
				N:    100000000, AllocsPerOp: 5,
				Measured: AllocsPerOp,
			},
			wanted: "BenchmarkTest 100000000 5 allocs/op",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := tt.input.String()
			if result != tt.wanted {
				t.Errorf("String() is called, want %q, have %q", tt.wanted, result)
			}
		})
	}
}


================================================
FILE: blog/atom/atom.go
================================================
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Adapted from encoding/xml/read_test.go.

// Package atom defines XML data structures for an Atom feed.
package atom // import "golang.org/x/tools/blog/atom"

import (
	"encoding/xml"
	"time"
)

type Feed struct {
	XMLName xml.Name `xml:"http://www.w3.org/2005/Atom feed"`
	Title   string   `xml:"title"`
	ID      string   `xml:"id"`
	Link    []Link   `xml:"link"`
	Updated TimeStr  `xml:"updated"`
	Author  *Person  `xml:"author"`
	Entry   []*Entry `xml:"entry"`
}

type Entry struct {
	Title     string  `xml:"title"`
	ID        string  `xml:"id"`
	Link      []Link  `xml:"link"`
	Published TimeStr `xml:"published"`
	Updated   TimeStr `xml:"updated"`
	Author    *Person `xml:"author"`
	Summary   *Text   `xml:"summary"`
	Content   *Text   `xml:"content"`
}

type Link struct {
	Rel      string `xml:"rel,attr,omitempty"`
	Href     string `xml:"href,attr"`
	Type     string `xml:"type,attr,omitempty"`
	HrefLang string `xml:"hreflang,attr,omitempty"`
	Title    string `xml:"title,attr,omitempty"`
	Length   uint   `xml:"length,attr,omitempty"`
}

type Person struct {
	Name     string `xml:"name"`
	URI      string `xml:"uri,omitempty"`
	Email    string `xml:"email,omitempty"`
	InnerXML string `xml:",innerxml"`
}

type Text struct {
	Type string `xml:"type,attr"`
	Body string `xml:",chardata"`
}

type TimeStr string

func Time(t time.Time) TimeStr {
	return TimeStr(t.Format("2006-01-02T15:04:05-07:00"))
}


================================================
FILE: blog/blog.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package blog implements a web server for articles written in present format.
package blog // import "golang.org/x/tools/blog"

import (
	"bytes"
	"encoding/json"
	"encoding/xml"
	"fmt"
	"html/template"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"time"

	"golang.org/x/tools/blog/atom"
	"golang.org/x/tools/present"
)

var (
	validJSONPFunc = regexp.MustCompile(`(?i)^[a-z_][a-z0-9_.]*$`)
	// used to serve relative paths when ServeLocalLinks is enabled.
	golangOrgAbsLinkReplacer = strings.NewReplacer(
		`href="https://golang.org/pkg`, `href="/pkg`,
		`href="https://golang.org/cmd`, `href="/cmd`,
	)
)

// Config specifies Server configuration values.
type Config struct {
	ContentPath  string // Relative or absolute location of article files and related content.
	TemplatePath string // Relative or absolute location of template files.

	BaseURL       string        // Absolute base URL (for permalinks; no trailing slash).
	BasePath      string        // Base URL path relative to server root (no trailing slash).
	GodocURL      string        // The base URL of godoc (for menu bar; no trailing slash).
	Hostname      string        // Server host name, used for rendering ATOM feeds.
	AnalyticsHTML template.HTML // Optional analytics HTML to insert at the beginning of <head>.

	HomeArticles int    // Articles to display on the home page.
	FeedArticles int    // Articles to include in Atom and JSON feeds.
	FeedTitle    string // The title of the Atom XML feed

	PlayEnabled     bool
	ServeLocalLinks bool // rewrite golang.org/{pkg,cmd} links to host-less, relative paths.
}

// Doc represents an article adorned with presentation data.
type Doc struct {
	*present.Doc
	Permalink string        // Canonical URL for this document.
	Path      string        // Path relative to server root (including base).
	HTML      template.HTML // rendered article

	Related      []*Doc
	Newer, Older *Doc
}

// Server implements an http.Handler that serves blog articles.
type Server struct {
	cfg       Config
	docs      []*Doc
	redirects map[string]string
	tags      []string
	docPaths  map[string]*Doc // key is path without BasePath.
	docTags   map[string][]*Doc
	template  struct {
		home, index, article, doc *template.Template
	}
	atomFeed []byte // pre-rendered Atom feed
	jsonFeed []byte // pre-rendered JSON feed
	content  http.Handler
}

// NewServer constructs a new Server using the specified config.
func NewServer(cfg Config) (*Server, error) {
	present.PlayEnabled = cfg.PlayEnabled

	if notExist(cfg.TemplatePath) {
		return nil, fmt.Errorf("template directory not found: %s", cfg.TemplatePath)
	}
	root := filepath.Join(cfg.TemplatePath, "root.tmpl")
	parse := func(name string) (*template.Template, error) {
		path := filepath.Join(cfg.TemplatePath, name)
		if notExist(path) {
			return nil, fmt.Errorf("template %s was not found in %s", name, cfg.TemplatePath)
		}
		t := template.New("").Funcs(funcMap)
		return t.ParseFiles(root, path)
	}

	s := &Server{cfg: cfg}

	// Parse templates.
	var err error
	s.template.home, err = parse("home.tmpl")
	if err != nil {
		return nil, err
	}
	s.template.index, err = parse("index.tmpl")
	if err != nil {
		return nil, err
	}
	s.template.article, err = parse("article.tmpl")
	if err != nil {
		return nil, err
	}
	p := present.Template().Funcs(funcMap)
	s.template.doc, err = p.ParseFiles(filepath.Join(cfg.TemplatePath, "doc.tmpl"))
	if err != nil {
		return nil, err
	}

	// Load content.
	content := filepath.Clean(cfg.ContentPath)
	err = s.loadDocs(content)
	if err != nil {
		return nil, err
	}

	err = s.renderAtomFeed()
	if err != nil {
		return nil, err
	}

	err = s.renderJSONFeed()
	if err != nil {
		return nil, err
	}

	// Set up content file server.
	s.content = http.StripPrefix(s.cfg.BasePath, http.FileServer(http.Dir(cfg.ContentPath)))

	return s, nil
}

var funcMap = template.FuncMap{
	"sectioned": sectioned,
	"authors":   authors,
}

// sectioned returns true if the provided Doc contains more than one section.
// This is used to control whether to display the table of contents and headings.
func sectioned(d *present.Doc) bool {
	return len(d.Sections) > 1
}

// authors returns a comma-separated list of author names.
func authors(authors []present.Author) string {
	var b bytes.Buffer
	last := len(authors) - 1
	for i, a := range authors {
		if i > 0 {
			if i == last {
				if len(authors) > 2 {
					b.WriteString(",")
				}
				b.WriteString(" and ")
			} else {
				b.WriteString(", ")
			}
		}
		b.WriteString(authorName(a))
	}
	return b.String()
}

// authorName returns the first line of the Author text: the author's name.
func authorName(a present.Author) string {
	el := a.TextElem()
	if len(el) == 0 {
		return ""
	}
	text, ok := el[0].(present.Text)
	if !ok || len(text.Lines) == 0 {
		return ""
	}
	return text.Lines[0]
}

// loadDocs reads all content from the provided file system root, renders all
// the articles it finds, adds them to the Server's docs field, computes the
// denormalized docPaths, docTags, and tags fields, and populates the various
// helper fields (Next, Previous, Related) for each Doc.
func (s *Server) loadDocs(root string) error {
	// Read content into docs field.
	const ext = ".article"
	fn := func(p string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		if filepath.Ext(p) != ext {
			return nil
		}
		f, err := os.Open(p)
		if err != nil {
			return err
		}
		defer f.Close()
		d, err := present.Parse(f, p, 0)
		if err != nil {
			return err
		}
		var html bytes.Buffer
		err = d.Render(&html, s.template.doc)
		if err != nil {
			return err
		}
		p = p[len(root) : len(p)-len(ext)] // trim root and extension
		p = filepath.ToSlash(p)
		s.docs = append(s.docs, &Doc{
			Doc:       d,
			Path:      s.cfg.BasePath + p,
			Permalink: s.cfg.BaseURL + p,
			HTML:      template.HTML(html.String()),
		})
		return nil
	}
	err := filepath.Walk(root, fn)
	if err != nil {
		return err
	}
	sort.Sort(docsByTime(s.docs))

	// Pull out doc paths and tags and put in reverse-associating maps.
	s.docPaths = make(map[string]*Doc)
	s.docTags = make(map[string][]*Doc)
	s.redirects = make(map[string]string)
	for _, d := range s.docs {
		s.docPaths[strings.TrimPrefix(d.Path, s.cfg.BasePath)] = d
		for _, t := range d.Tags {
			s.docTags[t] = append(s.docTags[t], d)
		}
	}
	for _, d := range s.docs {
		for _, old := range d.OldURL {
			if !strings.HasPrefix(old, "/") {
				old = "/" + old
			}
			if _, ok := s.docPaths[old]; ok {
				return fmt.Errorf("redirect %s -> %s conflicts with document %s", old, d.Path, old)
			}
			if new, ok := s.redirects[old]; ok {
				return fmt.Errorf("redirect %s -> %s conflicts with redirect %s -> %s", old, d.Path, old, new)
			}
			s.redirects[old] = d.Path
		}
	}

	// Pull out unique sorted list of tags.
	for t := range s.docTags {
		s.tags = append(s.tags, t)
	}
	sort.Strings(s.tags)

	// Set up presentation-related fields, Newer, Older, and Related.
	for _, doc := range s.docs {
		// Newer, Older: docs adjacent to doc
		for i := range s.docs {
			if s.docs[i] != doc {
				continue
			}
			if i > 0 {
				doc.Newer = s.docs[i-1]
			}
			if i+1 < len(s.docs) {
				doc.Older = s.docs[i+1]
			}
			break
		}

		// Related: all docs that share tags with doc.
		related := make(map[*Doc]bool)
		for _, t := range doc.Tags {
			for _, d := range s.docTags[t] {
				if d != doc {
					related[d] = true
				}
			}
		}
		for d := range related {
			doc.Related = append(doc.Related, d)
		}
		sort.Sort(docsByTime(doc.Related))
	}

	return nil
}

// renderAtomFeed generates an XML Atom feed and stores it in the Server's
// atomFeed field.
func (s *Server) renderAtomFeed() error {
	var updated time.Time
	if len(s.docs) > 0 {
		updated = s.docs[0].Time
	}
	feed := atom.Feed{
		Title:   s.cfg.FeedTitle,
		ID:      "tag:" + s.cfg.Hostname + ",2013:" + s.cfg.Hostname,
		Updated: atom.Time(updated),
		Link: []atom.Link{{
			Rel:  "self",
			Href: s.cfg.BaseURL + "/feed.atom",
		}},
	}
	for i, doc := range s.docs {
		if i >= s.cfg.FeedArticles {
			break
		}

		// Use original article path as ID in atom feed
		// to avoid articles being treated as new when renamed.
		idPath := doc.Path
		if len(doc.OldURL) > 0 {
			old := doc.OldURL[0]
			if !strings.HasPrefix(old, "/") {
				old = "/" + old
			}
			idPath = old
		}

		e := &atom.Entry{
			Title: doc.Title,
			ID:    feed.ID + idPath,
			Link: []atom.Link{{
				Rel:  "alternate",
				Href: doc.Permalink,
			}},
			Published: atom.Time(doc.Time),
			Updated:   atom.Time(doc.Time),
			Summary: &atom.Text{
				Type: "html",
				Body: summary(doc),
			},
			Content: &atom.Text{
				Type: "html",
				Body: string(doc.HTML),
			},
			Author: &atom.Person{
				Name: authors(doc.Authors),
			},
		}
		feed.Entry = append(feed.Entry, e)
	}
	data, err := xml.Marshal(&feed)
	if err != nil {
		return err
	}
	s.atomFeed = data
	return nil
}

type jsonItem struct {
	Title   string
	Link    string
	Time    time.Time
	Summary string
	Content string
	Author  string
}

// renderJSONFeed generates a JSON feed and stores it in the Server's jsonFeed
// field.
func (s *Server) renderJSONFeed() error {
	var feed []jsonItem
	for i, doc := range s.docs {
		if i >= s.cfg.FeedArticles {
			break
		}
		item := jsonItem{
			Title:   doc.Title,
			Link:    doc.Permalink,
			Time:    doc.Time,
			Summary: summary(doc),
			Content: string(doc.HTML),
			Author:  authors(doc.Authors),
		}
		feed = append(feed, item)
	}
	data, err := json.Marshal(feed)
	if err != nil {
		return err
	}
	s.jsonFeed = data
	return nil
}

// summary returns the first paragraph of text from the provided Doc.
func summary(d *Doc) string {
	if len(d.Sections) == 0 {
		return ""
	}
	for _, elem := range d.Sections[0].Elem {
		text, ok := elem.(present.Text)
		if !ok || text.Pre {
			// skip everything but non-text elements
			continue
		}
		var buf bytes.Buffer
		for _, s := range text.Lines {
			buf.WriteString(string(present.Style(s)))
			buf.WriteByte('\n')
		}
		return buf.String()
	}
	return ""
}

// rootData encapsulates data destined for the root template.
type rootData struct {
	Doc           *Doc
	BasePath      string
	GodocURL      string
	AnalyticsHTML template.HTML
	Data          any
}

// ServeHTTP serves the front, index, and article pages
// as well as the ATOM and JSON feeds.
func (s *Server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	var (
		d = rootData{
			BasePath:      s.cfg.BasePath,
			GodocURL:      s.cfg.GodocURL,
			AnalyticsHTML: s.cfg.AnalyticsHTML,
		}
		t *template.Template
	)
	switch p := strings.TrimPrefix(r.URL.Path, s.cfg.BasePath); p {
	case "/":
		d.Data = s.docs
		if len(s.docs) > s.cfg.HomeArticles {
			d.Data = s.docs[:s.cfg.HomeArticles]
		}
		t = s.template.home
	case "/index":
		d.Data = s.docs
		t = s.template.index
	case "/feed.atom", "/feeds/posts/default":
		w.Header().Set("Content-type", "application/atom+xml; charset=utf-8")
		w.Write(s.atomFeed)
		return
	case "/.json":
		if p := r.FormValue("jsonp"); validJSONPFunc.MatchString(p) {
			w.Header().Set("Content-type", "application/javascript; charset=utf-8")
			fmt.Fprintf(w, "%v(%s)", p, s.jsonFeed)
			return
		}
		w.Header().Set("Content-type", "application/json; charset=utf-8")
		w.Write(s.jsonFeed)
		return
	default:
		if redir, ok := s.redirects[p]; ok {
			http.Redirect(w, r, redir, http.StatusMovedPermanently)
			return
		}
		doc, ok := s.docPaths[p]
		if !ok {
			// Not a doc; try to just serve static content.
			s.content.ServeHTTP(w, r)
			return
		}
		d.Doc = doc
		t = s.template.article
	}
	var err error
	if s.cfg.ServeLocalLinks {
		var buf bytes.Buffer
		err = t.ExecuteTemplate(&buf, "root", d)
		if err != nil {
			log.Println(err)
			return
		}
		_, err = golangOrgAbsLinkReplacer.WriteString(w, buf.String())
	} else {
		err = t.ExecuteTemplate(w, "root", d)
	}
	if err != nil {
		log.Println(err)
	}
}

// docsByTime implements sort.Interface, sorting Docs by their Time field.
type docsByTime []*Doc

func (s docsByTime) Len() int           { return len(s) }
func (s docsByTime) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
func (s docsByTime) Less(i, j int) bool { return s[i].Time.After(s[j].Time) }

// notExist reports whether the path exists or not.
func notExist(path string) bool {
	_, err := os.Stat(path)
	return os.IsNotExist(err)
}


================================================
FILE: blog/blog_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package blog

import (
	"bytes"
	"testing"
)

func TestLinkRewrite(t *testing.T) {
	tests := []struct {
		input  string
		output string
	}{
		{
			`For instance, the <a href="https://golang.org/pkg/bytes/" target="_blank">bytes package</a> from the standard library exports the <code>Buffer</code> type.`,
			`For instance, the <a href="/pkg/bytes/" target="_blank">bytes package</a> from the standard library exports the <code>Buffer</code> type.`},
		{
			`(The <a href="https://golang.org/cmd/gofmt/" target="_blank">gofmt command</a> has a <code>-r</code> flag that provides a syntax-aware search and replace, making large-scale refactoring easier.)`,
			`(The <a href="/cmd/gofmt/" target="_blank">gofmt command</a> has a <code>-r</code> flag that provides a syntax-aware search and replace, making large-scale refactoring easier.)`,
		},
		{
			`<a href="//golang.org/LICENSE">BSD license</a>.<br> <a href="//golang.org/doc/tos.html">Terms of Service</a> `,
			`<a href="//golang.org/LICENSE">BSD license</a>.<br> <a href="//golang.org/doc/tos.html">Terms of Service</a> `,
		},
		{
			`For instance, the <code>websocket</code> package from the <code>go.net</code> sub-repository has an import path of <code>&#34;golang.org/x/net/websocket&#34;</code>.`,
			`For instance, the <code>websocket</code> package from the <code>go.net</code> sub-repository has an import path of <code>&#34;golang.org/x/net/websocket&#34;</code>.`,
		},
	}
	for _, test := range tests {
		var buf bytes.Buffer
		_, err := golangOrgAbsLinkReplacer.WriteString(&buf, test.input)
		if err != nil {
			t.Errorf("unexpected error during replacing links. Got: %#v, Want: nil.\n", err)
			continue
		}
		if got, want := buf.String(), test.output; got != want {
			t.Errorf("WriteString(%q) = %q. Expected: %q", test.input, got, want)
		}
	}
}


================================================
FILE: cmd/benchcmp/benchcmp.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"flag"
	"fmt"
	"os"
	"sort"
	"strconv"
	"text/tabwriter"

	"golang.org/x/tools/benchmark/parse"
)

var (
	changedOnly = flag.Bool("changed", false, "show only benchmarks that have changed")
	magSort     = flag.Bool("mag", false, "sort benchmarks by magnitude of change")
	best        = flag.Bool("best", false, "compare best times from old and new")
)

const usageFooter = `
Each input file should be from:
	go test -run=NONE -bench=. > [old,new].txt

Benchcmp compares old and new for each benchmark.

If -test.benchmem=true is added to the "go test" command
benchcmp will also compare memory allocations.
`

func main() {
	fmt.Fprintf(os.Stderr, "benchcmp is deprecated in favor of benchstat: https://pkg.go.dev/golang.org/x/perf/cmd/benchstat\n")
	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, "usage: %s old.txt new.txt\n\n", os.Args[0])
		flag.PrintDefaults()
		fmt.Fprint(os.Stderr, usageFooter)
		os.Exit(2)
	}
	flag.Parse()
	if flag.NArg() != 2 {
		flag.Usage()
	}

	before := parseFile(flag.Arg(0))
	after := parseFile(flag.Arg(1))

	cmps, warnings := Correlate(before, after)

	for _, warn := range warnings {
		fmt.Fprintln(os.Stderr, warn)
	}

	if len(cmps) == 0 {
		fatal("benchcmp: no repeated benchmarks")
	}

	w := new(tabwriter.Writer)
	w.Init(os.Stdout, 0, 0, 5, ' ', 0)
	defer w.Flush()

	var header bool // Has the header has been displayed yet for a given block?

	if *magSort {
		sort.Sort(ByDeltaNsPerOp(cmps))
	} else {
		sort.Sort(ByParseOrder(cmps))
	}
	for _, cmp := range cmps {
		if !cmp.Measured(parse.NsPerOp) {
			continue
		}
		if delta := cmp.DeltaNsPerOp(); !*changedOnly || delta.Changed() {
			if !header {
				fmt.Fprint(w, "benchmark\told ns/op\tnew ns/op\tdelta\n")
				header = true
			}
			fmt.Fprintf(w, "%s\t%s\t%s\t%s\n", cmp.Name(), formatNs(cmp.Before.NsPerOp), formatNs(cmp.After.NsPerOp), delta.Percent())
		}
	}

	header = false
	if *magSort {
		sort.Sort(ByDeltaMBPerS(cmps))
	}
	for _, cmp := range cmps {
		if !cmp.Measured(parse.MBPerS) {
			continue
		}
		if delta := cmp.DeltaMBPerS(); !*changedOnly || delta.Changed() {
			if !header {
				fmt.Fprint(w, "\nbenchmark\told MB/s\tnew MB/s\tspeedup\n")
				header = true
			}
			fmt.Fprintf(w, "%s\t%.2f\t%.2f\t%s\n", cmp.Name(), cmp.Before.MBPerS, cmp.After.MBPerS, delta.Multiple())
		}
	}

	header = false
	if *magSort {
		sort.Sort(ByDeltaAllocsPerOp(cmps))
	}
	for _, cmp := range cmps {
		if !cmp.Measured(parse.AllocsPerOp) {
			continue
		}
		if delta := cmp.DeltaAllocsPerOp(); !*changedOnly || delta.Changed() {
			if !header {
				fmt.Fprint(w, "\nbenchmark\told allocs\tnew allocs\tdelta\n")
				header = true
			}
			fmt.Fprintf(w, "%s\t%d\t%d\t%s\n", cmp.Name(), cmp.Before.AllocsPerOp, cmp.After.AllocsPerOp, delta.Percent())
		}
	}

	header = false
	if *magSort {
		sort.Sort(ByDeltaAllocedBytesPerOp(cmps))
	}
	for _, cmp := range cmps {
		if !cmp.Measured(parse.AllocedBytesPerOp) {
			continue
		}
		if delta := cmp.DeltaAllocedBytesPerOp(); !*changedOnly || delta.Changed() {
			if !header {
				fmt.Fprint(w, "\nbenchmark\told bytes\tnew bytes\tdelta\n")
				header = true
			}
			fmt.Fprintf(w, "%s\t%d\t%d\t%s\n", cmp.Name(), cmp.Before.AllocedBytesPerOp, cmp.After.AllocedBytesPerOp, cmp.DeltaAllocedBytesPerOp().Percent())
		}
	}
}

func fatal(msg any) {
	fmt.Fprintln(os.Stderr, msg)
	os.Exit(1)
}

func parseFile(path string) parse.Set {
	f, err := os.Open(path)
	if err != nil {
		fatal(err)
	}
	defer f.Close()
	bb, err := parse.ParseSet(f)
	if err != nil {
		fatal(err)
	}
	if *best {
		selectBest(bb)
	}
	return bb
}

func selectBest(bs parse.Set) {
	for name, bb := range bs {
		if len(bb) < 2 {
			continue
		}
		ord := bb[0].Ord
		best := bb[0]
		for _, b := range bb {
			if b.NsPerOp < best.NsPerOp {
				b.Ord = ord
				best = b
			}
		}
		bs[name] = []*parse.Benchmark{best}
	}
}

// formatNs formats ns measurements to expose a useful amount of
// precision. It mirrors the ns precision logic of testing.B.
func formatNs(ns float64) string {
	prec := 0
	switch {
	case ns < 10:
		prec = 2
	case ns < 100:
		prec = 1
	}
	return strconv.FormatFloat(ns, 'f', prec, 64)
}


================================================
FILE: cmd/benchcmp/benchcmp_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"reflect"
	"testing"

	"golang.org/x/tools/benchmark/parse"
)

func TestSelectBest(t *testing.T) {
	have := parse.Set{
		"Benchmark1": []*parse.Benchmark{
			{
				Name: "Benchmark1",
				N:    10, NsPerOp: 100, Measured: parse.NsPerOp,
				Ord: 0,
			},
			{
				Name: "Benchmark1",
				N:    10, NsPerOp: 50, Measured: parse.NsPerOp,
				Ord: 3,
			},
		},
		"Benchmark2": []*parse.Benchmark{
			{
				Name: "Benchmark2",
				N:    10, NsPerOp: 60, Measured: parse.NsPerOp,
				Ord: 1,
			},
			{
				Name: "Benchmark2",
				N:    10, NsPerOp: 500, Measured: parse.NsPerOp,
				Ord: 2,
			},
		},
	}

	want := parse.Set{
		"Benchmark1": []*parse.Benchmark{
			{
				Name: "Benchmark1",
				N:    10, NsPerOp: 50, Measured: parse.NsPerOp,
				Ord: 0,
			},
		},
		"Benchmark2": []*parse.Benchmark{
			{
				Name: "Benchmark2",
				N:    10, NsPerOp: 60, Measured: parse.NsPerOp,
				Ord: 1,
			},
		},
	}

	selectBest(have)
	if !reflect.DeepEqual(want, have) {
		t.Errorf("filtered bench set incorrectly, want %v have %v", want, have)
	}
}

func TestFormatNs(t *testing.T) {
	tests := []struct {
		input    float64
		expected string
	}{
		{input: 0, expected: "0.00"},
		{input: 0.2, expected: "0.20"},
		{input: 2, expected: "2.00"},
		{input: 2.2, expected: "2.20"},
		{input: 4, expected: "4.00"},
		{input: 16, expected: "16.0"},
		{input: 16.08, expected: "16.1"},
		{input: 128, expected: "128"},
		{input: 256.2, expected: "256"},
	}

	for _, tt := range tests {
		actual := formatNs(tt.input)
		if actual != tt.expected {
			t.Fatalf("%f. got %q, want %q", tt.input, actual, tt.expected)
		}
	}
}


================================================
FILE: cmd/benchcmp/compare.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"math"

	"golang.org/x/tools/benchmark/parse"
)

// BenchCmp is a pair of benchmarks.
type BenchCmp struct {
	Before *parse.Benchmark
	After  *parse.Benchmark
}

// Correlate correlates benchmarks from two BenchSets.
func Correlate(before, after parse.Set) (cmps []BenchCmp, warnings []string) {
	cmps = make([]BenchCmp, 0, len(after))
	for name, beforebb := range before {
		afterbb := after[name]
		if len(beforebb) != len(afterbb) {
			warnings = append(warnings, fmt.Sprintf("ignoring %s: before has %d instances, after has %d", name, len(beforebb), len(afterbb)))
			continue
		}
		for i, beforeb := range beforebb {
			afterb := afterbb[i]
			cmps = append(cmps, BenchCmp{beforeb, afterb})
		}
	}
	return
}

func (c BenchCmp) Name() string           { return c.Before.Name }
func (c BenchCmp) String() string         { return fmt.Sprintf("<%s, %s>", c.Before, c.After) }
func (c BenchCmp) Measured(flag int) bool { return (c.Before.Measured & c.After.Measured & flag) != 0 }
func (c BenchCmp) DeltaNsPerOp() Delta    { return Delta{c.Before.NsPerOp, c.After.NsPerOp} }
func (c BenchCmp) DeltaMBPerS() Delta     { return Delta{c.Before.MBPerS, c.After.MBPerS} }
func (c BenchCmp) DeltaAllocedBytesPerOp() Delta {
	return Delta{float64(c.Before.AllocedBytesPerOp), float64(c.After.AllocedBytesPerOp)}
}
func (c BenchCmp) DeltaAllocsPerOp() Delta {
	return Delta{float64(c.Before.AllocsPerOp), float64(c.After.AllocsPerOp)}
}

// Delta is the before and after value for a benchmark measurement.
// Both must be non-negative.
type Delta struct {
	Before float64
	After  float64
}

// mag calculates the magnitude of a change, regardless of the direction of
// the change. mag is intended for sorting and has no independent meaning.
func (d Delta) mag() float64 {
	switch {
	case d.Before != 0 && d.After != 0 && d.Before >= d.After:
		return d.After / d.Before
	case d.Before != 0 && d.After != 0 && d.Before < d.After:
		return d.Before / d.After
	case d.Before == 0 && d.After == 0:
		return 1
	default:
		// 0 -> 1 or 1 -> 0
		// These are significant changes and worth surfacing.
		return math.Inf(1)
	}
}

// Changed reports whether the benchmark quantities are different.
func (d Delta) Changed() bool { return d.Before != d.After }

// Float64 returns After / Before. If Before is 0, Float64 returns
// 1 if After is also 0, and +Inf otherwise.
func (d Delta) Float64() float64 {
	switch {
	case d.Before != 0:
		return d.After / d.Before
	case d.After == 0:
		return 1
	default:
		return math.Inf(1)
	}
}

// Percent formats a Delta as a percent change, ranging from -100% up.
func (d Delta) Percent() string {
	return fmt.Sprintf("%+.2f%%", 100*d.Float64()-100)
}

// Multiple formats a Delta as a multiplier, ranging from 0.00x up.
func (d Delta) Multiple() string {
	return fmt.Sprintf("%.2fx", d.Float64())
}

func (d Delta) String() string {
	return fmt.Sprintf("Δ(%f, %f)", d.Before, d.After)
}

// ByParseOrder sorts BenchCmps to match the order in
// which the Before benchmarks were presented to Parse.
type ByParseOrder []BenchCmp

func (x ByParseOrder) Len() int           { return len(x) }
func (x ByParseOrder) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
func (x ByParseOrder) Less(i, j int) bool { return x[i].Before.Ord < x[j].Before.Ord }

// lessByDelta provides lexicographic ordering:
//   - largest delta by magnitude
//   - alphabetic by name
func lessByDelta(i, j BenchCmp, calcDelta func(BenchCmp) Delta) bool {
	iDelta, jDelta := calcDelta(i).mag(), calcDelta(j).mag()
	if iDelta != jDelta {
		return iDelta < jDelta
	}
	return i.Name() < j.Name()
}

// ByDeltaNsPerOp sorts BenchCmps lexicographically by change
// in ns/op, descending, then by benchmark name.
type ByDeltaNsPerOp []BenchCmp

func (x ByDeltaNsPerOp) Len() int           { return len(x) }
func (x ByDeltaNsPerOp) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
func (x ByDeltaNsPerOp) Less(i, j int) bool { return lessByDelta(x[i], x[j], BenchCmp.DeltaNsPerOp) }

// ByDeltaMBPerS sorts BenchCmps lexicographically by change
// in MB/s, descending, then by benchmark name.
type ByDeltaMBPerS []BenchCmp

func (x ByDeltaMBPerS) Len() int           { return len(x) }
func (x ByDeltaMBPerS) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
func (x ByDeltaMBPerS) Less(i, j int) bool { return lessByDelta(x[i], x[j], BenchCmp.DeltaMBPerS) }

// ByDeltaAllocedBytesPerOp sorts BenchCmps lexicographically by change
// in B/op, descending, then by benchmark name.
type ByDeltaAllocedBytesPerOp []BenchCmp

func (x ByDeltaAllocedBytesPerOp) Len() int      { return len(x) }
func (x ByDeltaAllocedBytesPerOp) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaAllocedBytesPerOp) Less(i, j int) bool {
	return lessByDelta(x[i], x[j], BenchCmp.DeltaAllocedBytesPerOp)
}

// ByDeltaAllocsPerOp sorts BenchCmps lexicographically by change
// in allocs/op, descending, then by benchmark name.
type ByDeltaAllocsPerOp []BenchCmp

func (x ByDeltaAllocsPerOp) Len() int      { return len(x) }
func (x ByDeltaAllocsPerOp) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x ByDeltaAllocsPerOp) Less(i, j int) bool {
	return lessByDelta(x[i], x[j], BenchCmp.DeltaAllocsPerOp)
}


================================================
FILE: cmd/benchcmp/compare_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"math"
	"reflect"
	"sort"
	"testing"

	"golang.org/x/tools/benchmark/parse"
)

func TestDelta(t *testing.T) {
	cases := []struct {
		before  float64
		after   float64
		mag     float64
		f       float64
		changed bool
		pct     string
		mult    string
	}{
		{before: 1, after: 1, mag: 1, f: 1, changed: false, pct: "+0.00%", mult: "1.00x"},
		{before: 1, after: 2, mag: 0.5, f: 2, changed: true, pct: "+100.00%", mult: "2.00x"},
		{before: 2, after: 1, mag: 0.5, f: 0.5, changed: true, pct: "-50.00%", mult: "0.50x"},
		{before: 0, after: 0, mag: 1, f: 1, changed: false, pct: "+0.00%", mult: "1.00x"},
		{before: 1, after: 0, mag: math.Inf(1), f: 0, changed: true, pct: "-100.00%", mult: "0.00x"},
		{before: 0, after: 1, mag: math.Inf(1), f: math.Inf(1), changed: true, pct: "+Inf%", mult: "+Infx"},
	}
	for _, tt := range cases {
		d := Delta{tt.before, tt.after}
		if want, have := tt.mag, d.mag(); want != have {
			t.Errorf("%s.mag(): want %f have %f", d, want, have)
		}
		if want, have := tt.f, d.Float64(); want != have {
			t.Errorf("%s.Float64(): want %f have %f", d, want, have)
		}
		if want, have := tt.changed, d.Changed(); want != have {
			t.Errorf("%s.Changed(): want %t have %t", d, want, have)
		}
		if want, have := tt.pct, d.Percent(); want != have {
			t.Errorf("%s.Percent(): want %q have %q", d, want, have)
		}
		if want, have := tt.mult, d.Multiple(); want != have {
			t.Errorf("%s.Multiple(): want %q have %q", d, want, have)
		}
	}
}

func TestCorrelate(t *testing.T) {
	// Benches that are going to be successfully correlated get N thus:
	//   0x<counter><num benches><b = before | a = after>
	// Read this: "<counter> of <num benches>, from <before|after>".
	before := parse.Set{
		"BenchmarkOneEach":   []*parse.Benchmark{{Name: "BenchmarkOneEach", N: 0x11b}},
		"BenchmarkOneToNone": []*parse.Benchmark{{Name: "BenchmarkOneToNone"}},
		"BenchmarkOneToTwo":  []*parse.Benchmark{{Name: "BenchmarkOneToTwo"}},
		"BenchmarkTwoToOne": []*parse.Benchmark{
			{Name: "BenchmarkTwoToOne"},
			{Name: "BenchmarkTwoToOne"},
		},
		"BenchmarkTwoEach": []*parse.Benchmark{
			{Name: "BenchmarkTwoEach", N: 0x12b},
			{Name: "BenchmarkTwoEach", N: 0x22b},
		},
	}

	after := parse.Set{
		"BenchmarkOneEach":   []*parse.Benchmark{{Name: "BenchmarkOneEach", N: 0x11a}},
		"BenchmarkNoneToOne": []*parse.Benchmark{{Name: "BenchmarkNoneToOne"}},
		"BenchmarkTwoToOne":  []*parse.Benchmark{{Name: "BenchmarkTwoToOne"}},
		"BenchmarkOneToTwo": []*parse.Benchmark{
			{Name: "BenchmarkOneToTwo"},
			{Name: "BenchmarkOneToTwo"},
		},
		"BenchmarkTwoEach": []*parse.Benchmark{
			{Name: "BenchmarkTwoEach", N: 0x12a},
			{Name: "BenchmarkTwoEach", N: 0x22a},
		},
	}

	pairs, errs := Correlate(before, after)

	// Fail to match: BenchmarkOneToNone, BenchmarkOneToTwo, BenchmarkTwoToOne.
	// Correlate does not notice BenchmarkNoneToOne.
	if len(errs) != 3 {
		t.Errorf("Correlated expected 4 errors, got %d: %v", len(errs), errs)
	}

	// Want three correlated pairs: one BenchmarkOneEach, two BenchmarkTwoEach.
	if len(pairs) != 3 {
		t.Fatalf("Correlated expected 3 pairs, got %v", pairs)
	}

	for _, pair := range pairs {
		if pair.Before.N&0xF != 0xb {
			t.Errorf("unexpected Before in pair %s", pair)
		}
		if pair.After.N&0xF != 0xa {
			t.Errorf("unexpected After in pair %s", pair)
		}
		if pair.Before.N>>4 != pair.After.N>>4 {
			t.Errorf("mismatched pair %s", pair)
		}
	}
}

func TestBenchCmpSorting(t *testing.T) {
	c := []BenchCmp{
		{&parse.Benchmark{Name: "BenchmarkMuchFaster", NsPerOp: 10, Ord: 3}, &parse.Benchmark{Name: "BenchmarkMuchFaster", NsPerOp: 1}},
		{&parse.Benchmark{Name: "BenchmarkSameB", NsPerOp: 5, Ord: 1}, &parse.Benchmark{Name: "BenchmarkSameB", NsPerOp: 5}},
		{&parse.Benchmark{Name: "BenchmarkSameA", NsPerOp: 5, Ord: 2}, &parse.Benchmark{Name: "BenchmarkSameA", NsPerOp: 5}},
		{&parse.Benchmark{Name: "BenchmarkSlower", NsPerOp: 10, Ord: 0}, &parse.Benchmark{Name: "BenchmarkSlower", NsPerOp: 11}},
	}

	// Test just one magnitude-based sort order; they are symmetric.
	sort.Sort(ByDeltaNsPerOp(c))
	want := []string{"BenchmarkMuchFaster", "BenchmarkSlower", "BenchmarkSameA", "BenchmarkSameB"}
	have := []string{c[0].Name(), c[1].Name(), c[2].Name(), c[3].Name()}
	if !reflect.DeepEqual(want, have) {
		t.Errorf("ByDeltaNsOp incorrect sorting: want %v have %v", want, have)
	}

	sort.Sort(ByParseOrder(c))
	want = []string{"BenchmarkSlower", "BenchmarkSameB", "BenchmarkSameA", "BenchmarkMuchFaster"}
	have = []string{c[0].Name(), c[1].Name(), c[2].Name(), c[3].Name()}
	if !reflect.DeepEqual(want, have) {
		t.Errorf("ByParseOrder incorrect sorting: want %v have %v", want, have)
	}
}


================================================
FILE: cmd/benchcmp/doc.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Deprecated: benchcmp is deprecated in favor of benchstat: golang.org/x/perf/cmd/benchstat

The benchcmp command displays performance changes between benchmarks.

Benchcmp parses the output of two 'go test' benchmark runs,
correlates the results per benchmark, and displays the deltas.

To measure the performance impact of a change, use 'go test'
to run benchmarks before and after the change:

	go test -run=NONE -bench=. ./... > old.txt
	# make changes
	go test -run=NONE -bench=. ./... > new.txt

Then feed the benchmark results to benchcmp:

	benchcmp old.txt new.txt

Benchcmp will summarize and display the performance changes,
in a format like this:

	$ benchcmp old.txt new.txt
	benchmark           old ns/op     new ns/op     delta
	BenchmarkConcat     523           68.6          -86.88%

	benchmark           old allocs     new allocs     delta
	BenchmarkConcat     3              1              -66.67%

	benchmark           old bytes     new bytes     delta
	BenchmarkConcat     80            48            -40.00%
*/
package main // import "golang.org/x/tools/cmd/benchcmp"


================================================
FILE: cmd/bisect/go120.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"os"
	"os/exec"
	"time"
)

func cmdInterrupt(cmd *exec.Cmd) {
	cmd.Cancel = func() error {
		// On timeout, send interrupt,
		// in hopes of shutting down process tree.
		// Ignore errors sending signal; it's all best effort
		// and not even implemented on Windows.
		// TODO(rsc): Maybe use a new process group and kill the whole group?
		cmd.Process.Signal(os.Interrupt)
		return nil
	}
	cmd.WaitDelay = 2 * time.Second
}


================================================
FILE: cmd/bisect/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Bisect finds changes responsible for causing a failure.
// A typical use is to identify the source locations in a program
// that are miscompiled by a given compiler optimization.
//
// Usage:
//
//	bisect [flags] [var=value...] command [arguments...]
//
// Bisect operates on a target command line – the target – that can be
// run with various changes individually enabled or disabled. With none
// of the changes enabled, the target is known to succeed (exit with exit
// code zero). With all the changes enabled, the target is known to fail
// (exit any other way). Bisect repeats the target with different sets of
// changes enabled, using binary search to find (non-overlapping) minimal
// change sets that provoke the failure.
//
// The target must cooperate with bisect by accepting a change pattern
// and then enabling and reporting the changes that match that pattern.
// The change pattern is passed to the target by substituting it anywhere
// the string PATTERN appears in the environment values or the command
// arguments. For each change that matches the pattern, the target must
// enable that change and also print one or more “match lines”
// (to standard output or standard error) describing the change.
// The [golang.org/x/tools/internal/bisect] package provides functions to help
// targets implement this protocol. We plan to publish that package
// in a non-internal location after finalizing its API.
//
// Bisect starts by running the target with no changes enabled and then
// with all changes enabled. It expects the former to succeed and the latter to fail,
// and then it will search for the minimal set of changes that must be enabled
// to provoke the failure. If the situation is reversed – the target fails with no
// changes enabled and succeeds with all changes enabled – then bisect
// automatically runs in reverse as well, searching for the minimal set of changes
// that must be disabled to provoke the failure.
//
// Bisect prints tracing logs to standard error and the minimal change sets
// to standard output.
//
// # Command Line Flags
//
// Bisect supports the following command-line flags:
//
//	-max=M
//
// Stop after finding M minimal change sets. The default is no maximum, meaning to run until
// all changes that provoke a failure have been identified.
//
//	-maxset=S
//
// Disallow change sets larger than S elements. The default is no maximum.
//
//	-timeout=D
//
// If the target runs for longer than duration D, stop the target and interpret that as a failure.
// The default is no timeout.
//
//	-count=N
//
// Run each trial N times (default 2), checking for consistency.
//
//	-v
//
// Print verbose output, showing each run and its match lines.
//
// In addition to these general flags,
// bisect supports a few “shortcut” flags that make it more convenient
// to use with specific targets.
//
//	-compile=<rewrite>
//
// This flag is equivalent to adding an environment variable
// “GOCOMPILEDEBUG=<rewrite>hash=PATTERN”,
// which, as discussed in more detail in the example below,
// allows bisect to identify the specific source locations where the
// compiler rewrite causes the target to fail.
//
//	-godebug=<name>=<value>
//
// This flag is equivalent to adding an environment variable
// “GODEBUG=<name>=<value>#PATTERN”,
// which allows bisect to identify the specific call stacks where
// the changed [GODEBUG setting] value causes the target to fail.
//
// # Example
//
// The Go compiler provides support for enabling or disabling certain rewrites
// and optimizations to allow bisect to identify specific source locations where
// the rewrite causes the program to fail. For example, to bisect a failure caused
// by the new loop variable semantics:
//
//	bisect go test -gcflags=all=-d=loopvarhash=PATTERN
//
// The -gcflags=all= instructs the go command to pass the -d=... to the Go compiler
// when compiling all packages. Bisect varies PATTERN to determine the minimal set of changes
// needed to reproduce the failure.
//
// The go command also checks the GOCOMPILEDEBUG environment variable for flags
// to pass to the compiler, so the above command is equivalent to:
//
//	bisect GOCOMPILEDEBUG=loopvarhash=PATTERN go test
//
// Finally, as mentioned earlier, the -compile flag allows shortening this command further:
//
//	bisect -compile=loopvar go test
//
// # Defeating Build Caches
//
// Build systems cache build results, to avoid repeating the same compilations
// over and over. When using a cached build result, the go command (correctly)
// reprints the cached standard output and standard error associated with that
// command invocation. (This makes commands like 'go build -gcflags=-S' for
// printing an assembly listing work reliably.)
//
// Unfortunately, most build systems, including Bazel, are not as careful
// as the go command about reprinting compiler output. If the compiler is
// what prints match lines, a build system that suppresses compiler
// output when using cached compiler results will confuse bisect.
// To defeat such build caches, bisect replaces the literal text “RANDOM”
// in environment values and command arguments with a random 64-bit value
// during each invocation. The Go compiler conveniently accepts a
// -d=ignore=... debug flag that ignores its argument, so to run the
// previous example using Bazel, the invocation is:
//
//	bazel test --define=gc_goopts=-d=loopvarhash=PATTERN,unused=RANDOM //path/to:test
//
// [GODEBUG setting]: https://tip.golang.org/doc/godebug
package main

import (
	"context"
	"flag"
	"fmt"
	"io"
	"log"
	"math/bits"
	"math/rand"
	"os"
	"os/exec"
	"sort"
	"strconv"
	"strings"
	"time"

	"golang.org/x/tools/internal/bisect"
)

// Preserve import of bisect, to allow [bisect.Match] in the doc comment.
var _ bisect.Matcher

func usage() {
	fmt.Fprintf(os.Stderr, "usage: bisect [flags] [var=value...] command [arguments...]\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("bisect: ")

	var b Bisect
	b.Stdout = os.Stdout
	b.Stderr = os.Stderr
	flag.IntVar(&b.Max, "max", 0, "stop after finding `m` failing change sets")
	flag.IntVar(&b.MaxSet, "maxset", 0, "do not search for change sets larger than `s` elements")
	flag.DurationVar(&b.Timeout, "timeout", 0, "stop target and consider failed after duration `d`")
	flag.IntVar(&b.Count, "count", 2, "run target `n` times for each trial")
	flag.BoolVar(&b.Verbose, "v", false, "enable verbose output")

	env := ""
	envFlag := ""
	flag.Func("compile", "bisect source locations affected by Go compiler `rewrite` (fma, loopvar, ...)", func(value string) error {
		if envFlag != "" {
			return fmt.Errorf("cannot use -%s and -compile", envFlag)
		}
		envFlag = "compile"
		env = "GOCOMPILEDEBUG=" + value + "hash=PATTERN"
		return nil
	})
	flag.Func("godebug", "bisect call stacks affected by GODEBUG setting `name=value`", func(value string) error {
		if envFlag != "" {
			return fmt.Errorf("cannot use -%s and -godebug", envFlag)
		}
		envFlag = "godebug"
		env = "GODEBUG=" + value + "#PATTERN"
		return nil
	})

	flag.Usage = usage
	flag.Parse()
	args := flag.Args()

	// Split command line into env settings, command name, args.
	i := 0
	for i < len(args) && strings.Contains(args[i], "=") {
		i++
	}
	if i == len(args) {
		usage()
	}
	b.Env, b.Cmd, b.Args = args[:i], args[i], args[i+1:]
	if env != "" {
		b.Env = append([]string{env}, b.Env...)
	}

	// Check that PATTERN is available for us to vary.
	found := false
	for _, e := range b.Env {
		if _, v, _ := strings.Cut(e, "="); strings.Contains(v, "PATTERN") {
			found = true
		}
	}
	for _, a := range b.Args {
		if strings.Contains(a, "PATTERN") {
			found = true
		}
	}
	if !found {
		log.Fatalf("no PATTERN in target environment or args")
	}

	if !b.Search() {
		os.Exit(1)
	}
}

// A Bisect holds the state for a bisect invocation.
type Bisect struct {
	// Env is the additional environment variables for the command.
	// PATTERN and RANDOM are substituted in the values, but not the names.
	Env []string

	// Cmd is the command (program name) to run.
	// PATTERN and RANDOM are not substituted.
	Cmd string

	// Args is the command arguments.
	// PATTERN and RANDOM are substituted anywhere they appear.
	Args []string

	// Command-line flags controlling bisect behavior.
	Max     int           // maximum number of sets to report (0 = unlimited)
	MaxSet  int           // maximum number of elements in a set (0 = unlimited)
	Timeout time.Duration // kill target and assume failed after this duration (0 = unlimited)
	Count   int           // run target this many times for each trial and give up if flaky (min 1 assumed; default 2 on command line set in main)
	Verbose bool          // print long output about each trial (only useful for debugging bisect itself)

	// State for running bisect, replaced during testing.
	// Failing change sets are printed to Stdout; all other output goes to Stderr.
	Stdout  io.Writer                                                             // where to write standard output (usually os.Stdout)
	Stderr  io.Writer                                                             // where to write standard error (usually os.Stderr)
	TestRun func(env []string, cmd string, args []string) (out []byte, err error) // if non-nil, used instead of exec.Command

	// State maintained by Search.

	// By default, Search looks for a minimal set of changes that cause a failure when enabled.
	// If Disable is true, the search is inverted and seeks a minimal set of changes that
	// cause a failure when disabled. In this case, the search proceeds as normal except that
	// each pattern starts with a !.
	Disable bool

	// SkipHexDigits is the number of hex digits to use in skip messages.
	// If the set of available changes is the same in each run, as it should be,
	// then this doesn't matter: we'll only exclude suffixes that uniquely identify
	// a given change. But for some programs, especially bisecting runtime
	// behaviors, sometimes enabling one change unlocks questions about other
	// changes. Strictly speaking this is a misuse of bisect, but just to make
	// bisect more robust, we use the y and n runs to create an estimate of the
	// number of bits needed for a unique suffix, and then we round it up to
	// a number of hex digits, with one extra digit for good measure, and then
	// we always use that many hex digits for skips.
	SkipHexDigits int

	// Add is a list of suffixes to add to every trial, because they
	// contain changes that are necessary for a group we are assembling.
	Add []string

	// Skip is a list of suffixes that uniquely identify changes to exclude from every trial,
	// because they have already been used in failing change sets.
	// Suffixes later in the list may only be unique after removing
	// the ones earlier in the list.
	// Skip applies after Add.
	Skip []string
}

// A Result holds the result of a single target trial.
type Result struct {
	Success bool   // whether the target succeeded (exited with zero status)
	Cmd     string // full target command line
	Out     string // full target output (stdout and stderr combined)

	Suffix    string   // the suffix used for collecting MatchIDs, MatchText, and MatchFull
	MatchIDs  []uint64 // match IDs enabled during this trial
	MatchText []string // match reports for the IDs, with match markers removed
	MatchFull []string // full match lines for the IDs, with match markers kept
}

// &searchFatal is a special panic value to signal that Search failed.
// This lets us unwind the search recursion on a fatal error
// but have Search return normally.
var searchFatal int

// Search runs a bisect search according to the configuration in b.
// It reports whether any failing change sets were found.
func (b *Bisect) Search() bool {
	defer func() {
		// Recover from panic(&searchFatal), implicitly returning false from Search.
		// Re-panic on any other panic.
		if e := recover(); e != nil && e != &searchFatal {
			panic(e)
		}
	}()

	// Run with no changes and all changes, to figure out which direction we're searching.
	// The goal is to find the minimal set of changes to toggle
	// starting with the state where everything works.
	// If "no changes" succeeds and "all changes" fails,
	// we're looking for a minimal set of changes to enable to provoke the failure
	// (broken = runY, b.Negate = false)
	// If "no changes" fails and "all changes" succeeds,
	// we're looking for a minimal set of changes to disable to provoke the failure
	// (broken = runN, b.Negate = true).

	b.Logf("checking target with all changes disabled")
	runN := b.Run("n")

	b.Logf("checking target with all changes enabled")
	runY := b.Run("y")

	var broken *Result
	switch {
	case runN.Success && !runY.Success:
		b.Logf("target succeeds with no changes, fails with all changes")
		b.Logf("searching for minimal set of enabled changes causing failure")
		broken = runY
		b.Disable = false

	case !runN.Success && runY.Success:
		b.Logf("target fails with no changes, succeeds with all changes")
		b.Logf("searching for minimal set of disabled changes causing failure")
		broken = runN
		b.Disable = true

	case runN.Success && runY.Success:
		b.Fatalf("target succeeds with no changes and all changes")

	case !runN.Success && !runY.Success:
		b.Fatalf("target fails with no changes and all changes")
	}

	// Compute minimum number of bits needed to distinguish
	// all the changes we saw during N and all the changes we saw during Y.
	b.SkipHexDigits = skipHexDigits(runN.MatchIDs, runY.MatchIDs)

	// Loop finding and printing change sets, until none remain.
	found := 0
	for {
		// Find set.
		bad := b.search(broken)
		if bad == nil {
			if found == 0 {
				b.Fatalf("cannot find any failing change sets of size ≤ %d", b.MaxSet)
			}
			break
		}

		// Confirm that set really does fail, to avoid false accusations.
		// Also asking for user-visible output; earlier runs did not.
		b.Logf("confirming failing change set")
		b.Add = append(b.Add[:0], bad...)
		broken = b.Run("v")
		if broken.Success {
			b.Logf("confirmation run succeeded unexpectedly")
		}
		b.Add = b.Add[:0]

		// Print confirmed change set.
		found++
		b.Logf("FOUND failing change set")
		desc := "(enabling changes causes failure)"
		if b.Disable {
			desc = "(disabling changes causes failure)"
		}
		fmt.Fprintf(b.Stdout, "--- change set #%d %s\n%s\n---\n", found, desc, strings.Join(broken.MatchText, "\n"))

		// Stop if we've found enough change sets.
		if b.Max > 0 && found >= b.Max {
			break
		}

		// If running bisect target | tee bad.txt, prints to stdout and stderr
		// both appear on the terminal, but the ones to stdout go through tee
		// and can take a little bit of extra time. Sleep 1 millisecond to give
		// tee time to catch up, so that its stdout print does not get interlaced
		// with the stderr print from the next b.Log message.
		time.Sleep(1 * time.Millisecond)

		// Disable the now-known-bad changes and see if any failures remain.
		b.Logf("checking for more failures")
		b.Skip = append(bad, b.Skip...)
		broken = b.Run("")
		if broken.Success {
			what := "enabled"
			if b.Disable {
				what = "disabled"
			}
			b.Logf("target succeeds with all remaining changes %s", what)
			break
		}
		b.Logf("target still fails; searching for more bad changes")
	}
	return true
}

// Fatalf prints a message to standard error and then panics,
// causing Search to return false.
func (b *Bisect) Fatalf(format string, args ...any) {
	s := fmt.Sprintf("bisect: fatal error: "+format, args...)
	if !strings.HasSuffix(s, "\n") {
		s += "\n"
	}
	b.Stderr.Write([]byte(s))
	panic(&searchFatal)
}

// Logf prints a message to standard error.
func (b *Bisect) Logf(format string, args ...any) {
	s := fmt.Sprintf("bisect: "+format, args...)
	if !strings.HasSuffix(s, "\n") {
		s += "\n"
	}
	b.Stderr.Write([]byte(s))
}

func skipHexDigits(idY, idN []uint64) int {
	var all []uint64
	seen := make(map[uint64]bool)
	for _, x := range idY {
		seen[x] = true
		all = append(all, x)
	}
	for _, x := range idN {
		if !seen[x] {
			seen[x] = true
			all = append(all, x)
		}
	}
	sort.Slice(all, func(i, j int) bool { return bits.Reverse64(all[i]) < bits.Reverse64(all[j]) })
	digits := sort.Search(64/4, func(digits int) bool {
		mask := uint64(1)<<(4*digits) - 1
		for i := 0; i+1 < len(all); i++ {
			if all[i]&mask == all[i+1]&mask {
				return false
			}
		}
		return true
	})
	if digits < 64/4 {
		digits++
	}
	return digits
}

// search searches for a single locally minimal change set.
//
// Invariant: r describes the result of r.Suffix + b.Add, which failed.
// (There's an implicit -b.Skip everywhere here. b.Skip does not change.)
// We want to extend r.Suffix to preserve the failure, working toward
// a suffix that identifies a single change.
func (b *Bisect) search(r *Result) []string {
	// The caller should be passing in a failure result that we diagnose.
	if r.Success {
		b.Fatalf("internal error: unexpected success") // mistake by caller
	}

	// If the failure reported no changes, the target is misbehaving.
	if len(r.MatchIDs) == 0 {
		b.Fatalf("failure with no reported changes:\n\n$ %s\n%s\n", r.Cmd, r.Out)
	}

	// If there's one matching change, that's the one we're looking for.
	if len(r.MatchIDs) == 1 {
		return []string{fmt.Sprintf("x%0*x", b.SkipHexDigits, r.MatchIDs[0]&(1<<(4*b.SkipHexDigits)-1))}
	}

	// If the suffix we were tracking in the trial is already 64 bits,
	// either the target is bad or bisect itself is buggy.
	if len(r.Suffix) >= 64 {
		b.Fatalf("failed to isolate a single change with very long suffix")
	}

	// We want to split the current matchIDs by left-extending the suffix with 0 and 1.
	// If all the matches have the same next bit, that won't cause a split, which doesn't
	// break the algorithm but does waste time. Avoid wasting time by left-extending
	// the suffix to the longest suffix shared by all the current match IDs
	// before adding 0 or 1.
	suffix := commonSuffix(r.MatchIDs)
	if !strings.HasSuffix(suffix, r.Suffix) {
		b.Fatalf("internal error: invalid common suffix") // bug in commonSuffix
	}

	// Run 0suffix and 1suffix. If one fails, chase down the failure in that half.
	r0 := b.Run("0" + suffix)
	if !r0.Success {
		return b.search(r0)
	}
	r1 := b.Run("1" + suffix)
	if !r1.Success {
		return b.search(r1)
	}

	// suffix failed, but 0suffix and 1suffix succeeded.
	// Assuming the target isn't flaky, this means we need
	// at least one change from 0suffix AND at least one from 1suffix.
	// We are already tracking N = len(b.Add) other changes and are
	// allowed to build sets of size at least 1+N (or we shouldn't be here at all).
	// If we aren't allowed to build sets of size 2+N, give up this branch.
	if b.MaxSet > 0 && 2+len(b.Add) > b.MaxSet {
		return nil
	}

	// Adding all matches for 1suffix, recurse to narrow down 0suffix.
	old := len(b.Add)
	b.Add = append(b.Add, "1"+suffix)
	r0 = b.Run("0" + suffix)
	if r0.Success {
		// 0suffix + b.Add + 1suffix = suffix + b.Add is what r describes, and it failed.
		b.Fatalf("target fails inconsistently")
	}
	bad0 := b.search(r0)
	if bad0 == nil {
		// Search failed due to MaxSet limit.
		return nil
	}
	b.Add = b.Add[:old]

	// Adding the specific match we found in 0suffix, recurse to narrow down 1suffix.
	b.Add = append(b.Add[:old], bad0...)
	r1 = b.Run("1" + suffix)
	if r1.Success {
		// 1suffix + b.Add + bad0 = bad0 + b.Add + 1suffix is what b.search(r0) reported as a failure.
		b.Fatalf("target fails inconsistently")
	}
	bad1 := b.search(r1)
	if bad1 == nil {
		// Search failed due to MaxSet limit.
		return nil
	}
	b.Add = b.Add[:old]

	// bad0 and bad1 together provoke the failure.
	return append(bad0, bad1...)
}

// Run runs a set of trials selecting changes with the given suffix,
// plus the ones in b.Add and not the ones in b.Skip.
// The returned result's MatchIDs, MatchText, and MatchFull
// only list the changes that match suffix.
// When b.Count > 1, Run runs b.Count trials and requires
// that they all succeed or they all fail. If not, it calls b.Fatalf.
func (b *Bisect) Run(suffix string) *Result {
	out := b.run(suffix)
	for i := 1; i < b.Count; i++ {
		r := b.run(suffix)
		if r.Success != out.Success {
			b.Fatalf("target fails inconsistently")
		}
	}
	return out
}

// run runs a single trial for Run.
func (b *Bisect) run(suffix string) *Result {
	random := fmt.Sprint(rand.Uint64())

	// Accept suffix == "v" to mean we need user-visible output.
	visible := ""
	if suffix == "v" {
		visible = "v"
		suffix = ""
	}

	// Construct change ID pattern.
	var pattern string
	if suffix == "y" || suffix == "n" {
		pattern = suffix
		suffix = ""
	} else {
		var elem []string
		if suffix != "" {
			elem = append(elem, "+", suffix)
		}
		for _, x := range b.Add {
			elem = append(elem, "+", x)
		}
		for _, x := range b.Skip {
			elem = append(elem, "-", x)
		}
		pattern = strings.Join(elem, "")
		if pattern == "" {
			pattern = "y"
		}
	}
	if b.Disable {
		pattern = "!" + pattern
	}
	pattern = visible + pattern

	// Construct substituted env and args.
	env := make([]string, len(b.Env))
	for i, x := range b.Env {
		k, v, _ := strings.Cut(x, "=")
		env[i] = k + "=" + replace(v, pattern, random)
	}
	args := make([]string, len(b.Args))
	for i, x := range b.Args {
		args[i] = replace(x, pattern, random)
	}

	// Construct and log command line.
	// There is no newline in the log print.
	// The line will be completed when the command finishes.
	cmdText := strings.Join(append(append(env, b.Cmd), args...), " ")
	fmt.Fprintf(b.Stderr, "bisect: run: %s...", cmdText)

	// Run command with args and env.
	var out []byte
	var err error
	if b.TestRun != nil {
		out, err = b.TestRun(env, b.Cmd, args)
	} else {
		ctx := context.Background()
		if b.Timeout != 0 {
			var cancel context.CancelFunc
			ctx, cancel = context.WithTimeout(ctx, b.Timeout)
			defer cancel()
		}
		cmd := exec.CommandContext(ctx, b.Cmd, args...)
		cmd.Env = append(os.Environ(), env...)
		// Set up cmd.Cancel, cmd.WaitDelay on Go 1.20 and later
		// TODO(rsc): Inline go120.go's cmdInterrupt once we stop supporting Go 1.19.
		cmdInterrupt(cmd)
		out, err = cmd.CombinedOutput()
	}

	// Parse output to construct result.
	r := &Result{
		Suffix:  suffix,
		Success: err == nil,
		Cmd:     cmdText,
		Out:     string(out),
	}

	// Calculate bits, mask to identify suffix matches.
	var bits, mask uint64
	if suffix != "" && suffix != "y" && suffix != "n" && suffix != "v" {
		var err error
		bits, err = strconv.ParseUint(suffix, 2, 64)
		if err != nil {
			b.Fatalf("internal error: bad suffix")
		}
		mask = uint64(1<<len(suffix)) - 1
	}

	// Process output, collecting match reports for suffix.
	have := make(map[uint64]bool)
	all := r.Out
	for all != "" {
		var line string
		line, all, _ = strings.Cut(all, "\n")
		short, id, ok := bisect.CutMarker(line)
		if !ok || (id&mask) != bits {
			continue
		}

		if !have[id] {
			have[id] = true
			r.MatchIDs = append(r.MatchIDs, id)
		}
		r.MatchText = append(r.MatchText, short)
		r.MatchFull = append(r.MatchFull, line)
	}

	// Finish log print from above, describing the command's completion.
	if err == nil {
		fmt.Fprintf(b.Stderr, " ok (%d matches)\n", len(r.MatchIDs))
	} else {
		fmt.Fprintf(b.Stderr, " FAIL (%d matches)\n", len(r.MatchIDs))
	}

	if err != nil && len(r.MatchIDs) == 0 {
		b.Fatalf("target failed without printing any matches\n%s", r.Out)
	}

	// In verbose mode, print extra debugging: all the lines with match markers.
	if b.Verbose {
		b.Logf("matches:\n%s", strings.Join(r.MatchFull, "\n\t"))
	}

	return r
}

// replace returns x with literal text PATTERN and RANDOM replaced by pattern and random.
func replace(x, pattern, random string) string {
	x = strings.ReplaceAll(x, "PATTERN", pattern)
	x = strings.ReplaceAll(x, "RANDOM", random)
	return x
}

// commonSuffix returns the longest common binary suffix shared by all uint64s in list.
// If list is empty, commonSuffix returns an empty string.
func commonSuffix(list []uint64) string {
	if len(list) == 0 {
		return ""
	}
	b := list[0]
	n := 64
	for _, x := range list {
		for x&((1<<n)-1) != b {
			n--
			b &= (1 << n) - 1
		}
	}
	s := make([]byte, n)
	for i := n - 1; i >= 0; i-- {
		s[i] = '0' + byte(b&1)
		b >>= 1
	}
	return string(s[:])
}


================================================
FILE: cmd/bisect/main_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/build/constraint"
	"math/rand"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"golang.org/x/tools/internal/bisect"
	"golang.org/x/tools/internal/diffp"
	"golang.org/x/tools/txtar"
)

var update = flag.Bool("update", false, "update testdata with new stdout/stderr")

func Test(t *testing.T) {
	files, err := filepath.Glob("testdata/*.txt")
	if err != nil {
		t.Fatal(err)
	}
	for _, file := range files {
		t.Run(strings.TrimSuffix(filepath.Base(file), ".txt"), func(t *testing.T) {
			data, err := os.ReadFile(file)
			if err != nil {
				t.Fatal(err)
			}
			a := txtar.Parse(data)
			var wantStdout, wantStderr []byte
			files := a.Files
			if len(files) > 0 && files[0].Name == "stdout" {
				wantStdout = files[0].Data
				files = files[1:]
			}
			if len(files) > 0 && files[0].Name == "stderr" {
				wantStderr = files[0].Data
				files = files[1:]
			}
			if len(files) > 0 {
				t.Fatalf("unexpected txtar entry: %s", files[0].Name)
			}

			var tt struct {
				Fail   string
				Bisect Bisect
			}
			if err := json.Unmarshal(a.Comment, &tt); err != nil {
				t.Fatal(err)
			}

			expr, err := constraint.Parse("//go:build " + tt.Fail)
			if err != nil {
				t.Fatalf("invalid Cmd: %v", err)
			}

			rnd := rand.New(rand.NewSource(1))
			b := &tt.Bisect
			b.Cmd = "test"
			b.Args = []string{"PATTERN"}
			var stdout, stderr bytes.Buffer
			b.Stdout = &stdout
			b.Stderr = &stderr
			b.TestRun = func(env []string, cmd string, args []string) (out []byte, err error) {
				pattern := args[0]
				m, err := bisect.New(pattern)
				if err != nil {
					t.Fatal(err)
				}
				have := make(map[string]bool)
				for i, color := range colors {
					if m.ShouldEnable(uint64(i)) {
						have[color] = true
					}
					if m.ShouldReport(uint64(i)) {
						out = fmt.Appendf(out, "%s %s\n", color, bisect.Marker(uint64(i)))
					}
				}
				err = nil
				if eval(rnd, expr, have) {
					err = fmt.Errorf("failed")
				}
				return out, err
			}

			if !b.Search() {
				stderr.WriteString("<bisect failed>\n")
			}
			rewrite := false
			if !bytes.Equal(stdout.Bytes(), wantStdout) {
				if *update {
					rewrite = true
				} else {
					t.Errorf("incorrect stdout: %s", diffp.Diff("have", stdout.Bytes(), "want", wantStdout))
				}
			}
			if !bytes.Equal(stderr.Bytes(), wantStderr) {
				if *update {
					rewrite = true
				} else {
					t.Errorf("incorrect stderr: %s", diffp.Diff("have", stderr.Bytes(), "want", wantStderr))
				}
			}
			if rewrite {
				a.Files = []txtar.File{{Name: "stdout", Data: stdout.Bytes()}, {Name: "stderr", Data: stderr.Bytes()}}
				err := os.WriteFile(file, txtar.Format(a), 0666)
				if err != nil {
					t.Fatal(err)
				}
				t.Logf("updated %s", file)
			}
		})
	}
}

func eval(rnd *rand.Rand, z constraint.Expr, have map[string]bool) bool {
	switch z := z.(type) {
	default:
		panic(fmt.Sprintf("unexpected type %T", z))
	case *constraint.NotExpr:
		return !eval(rnd, z.X, have)
	case *constraint.AndExpr:
		return eval(rnd, z.X, have) && eval(rnd, z.Y, have)
	case *constraint.OrExpr:
		return eval(rnd, z.X, have) || eval(rnd, z.Y, have)
	case *constraint.TagExpr:
		if z.Tag == "random" {
			return rnd.Intn(2) == 1
		}
		return have[z.Tag]
	}
}

var colors = strings.Fields(`
	aliceblue
	amaranth
	amber
	amethyst
	applegreen
	applered
	apricot
	aquamarine
	azure
	babyblue
	beige
	brickred
	black
	blue
	bluegreen
	blueviolet
	blush
	bronze
	brown
	burgundy
	byzantium
	carmine
	cerise
	cerulean
	champagne
	chartreusegreen
	chocolate
	cobaltblue
	coffee
	copper
	coral
	crimson
	cyan
	desertsand
	electricblue
	emerald
	erin
	gold
	gray
	green
	harlequin
	indigo
	ivory
	jade
	junglegreen
	lavender
	lemon
	lilac
	lime
	magenta
	magentarose
	maroon
	mauve
	navyblue
	ochre
	olive
	orange
	orangered
	orchid
	peach
	pear
	periwinkle
	persianblue
	pink
	plum
	prussianblue
	puce
	purple
	raspberry
	red
	redviolet
	rose
	ruby
	salmon
	sangria
	sapphire
	scarlet
	silver
	slategray
	springbud
	springgreen
	tan
	taupe
	teal
	turquoise
	ultramarine
	violet
	viridian
	white
	yellow
`)


================================================
FILE: cmd/bisect/testdata/README.md
================================================
This directory contains test inputs for the bisect command.

Each text file is a txtar archive (see <https://pkg.go.dev/golang.org/x/tools/txtar>
or `go doc txtar`).

The comment at the top of the archive is a JSON object describing a
target behavior. Specifically, the Fail key gives a boolean expression
that should provoke a failure. Bisect's job is to discover this
condition.

The Bisect key describes settings in the Bisect struct that we want to
change, to simulate the use of various command-line options.

The txtar archive files should be "stdout" and "stderr", giving the
expected standard output and standard error. If the bisect command
should exit with a non-zero status, the stderr in the archive will end
with the line "<bisect failed>".

Running `go test -update` will rewrite the stdout and stderr files in
each testdata archive to match the current state of the tool. This is
a useful command when the logging prints from bisect change or when
writing a new test.

To use `go test -update` to write a new test:

 - Create a new .txt file with just a JSON object at the top,
   specifying what you want to test.
 - Run `go test -update`.
 - Reload the .txt file and read the stdout and stderr to see if you agree.


================================================
FILE: cmd/bisect/testdata/basic.txt
================================================
{"Fail": "amber || apricot"}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
apricot
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... FAIL (44 matches)
bisect: run: test +00-x002... ok (23 matches)
bisect: run: test +10-x002... FAIL (21 matches)
bisect: run: test +010-x002... ok (10 matches)
bisect: run: test +110-x002... FAIL (11 matches)
bisect: run: test +0110-x002... FAIL (6 matches)
bisect: run: test +00110-x002... FAIL (3 matches)
bisect: run: test +000110-x002... FAIL (2 matches)
bisect: run: test +0000110-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x006-x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x006-x002... ok (88 matches)
bisect: target succeeds with all remaining changes enabled


================================================
FILE: cmd/bisect/testdata/count2.txt
================================================
{"Fail": "amber || apricot", "Bisect": {"Count": 2}}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
apricot
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... FAIL (44 matches)
bisect: run: test +0-x002... FAIL (44 matches)
bisect: run: test +00-x002... ok (23 matches)
bisect: run: test +00-x002... ok (23 matches)
bisect: run: test +10-x002... FAIL (21 matches)
bisect: run: test +10-x002... FAIL (21 matches)
bisect: run: test +010-x002... ok (10 matches)
bisect: run: test +010-x002... ok (10 matches)
bisect: run: test +110-x002... FAIL (11 matches)
bisect: run: test +110-x002... FAIL (11 matches)
bisect: run: test +0110-x002... FAIL (6 matches)
bisect: run: test +0110-x002... FAIL (6 matches)
bisect: run: test +00110-x002... FAIL (3 matches)
bisect: run: test +00110-x002... FAIL (3 matches)
bisect: run: test +000110-x002... FAIL (2 matches)
bisect: run: test +000110-x002... FAIL (2 matches)
bisect: run: test +0000110-x002... FAIL (1 matches)
bisect: run: test +0000110-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x006-x002... FAIL (1 matches)
bisect: run: test v+x006-x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x006-x002... ok (88 matches)
bisect: run: test -x006-x002... ok (88 matches)
bisect: target succeeds with all remaining changes enabled


================================================
FILE: cmd/bisect/testdata/double.txt
================================================
{"Fail": "amber || apricot && peach"}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
apricot
peach
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... ok (44 matches)
bisect: run: test +1-x002... ok (45 matches)
bisect: run: test +0+1-x002... FAIL (44 matches)
bisect: run: test +00+1-x002... ok (23 matches)
bisect: run: test +10+1-x002... FAIL (21 matches)
bisect: run: test +010+1-x002... ok (10 matches)
bisect: run: test +110+1-x002... FAIL (11 matches)
bisect: run: test +0110+1-x002... FAIL (6 matches)
bisect: run: test +00110+1-x002... FAIL (3 matches)
bisect: run: test +000110+1-x002... FAIL (2 matches)
bisect: run: test +0000110+1-x002... FAIL (1 matches)
bisect: run: test +1+x006-x002... FAIL (45 matches)
bisect: run: test +01+x006-x002... ok (23 matches)
bisect: run: test +11+x006-x002... FAIL (22 matches)
bisect: run: test +011+x006-x002... FAIL (11 matches)
bisect: run: test +0011+x006-x002... ok (6 matches)
bisect: run: test +1011+x006-x002... FAIL (5 matches)
bisect: run: test +01011+x006-x002... ok (3 matches)
bisect: run: test +11011+x006-x002... FAIL (2 matches)
bisect: run: test +011011+x006-x002... ok (1 matches)
bisect: run: test +111011+x006-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x006+x03b-x002... FAIL (2 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x006-x03b-x002... ok (87 matches)
bisect: target succeeds with all remaining changes enabled


================================================
FILE: cmd/bisect/testdata/max1.txt
================================================
{"Fail": "amber || apricot && peach", "Bisect": {"Max": 1}}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set


================================================
FILE: cmd/bisect/testdata/max2.txt
================================================
{"Fail": "amber || apricot && peach || red && green && blue || cyan && magenta && yellow && black", "Bisect": {"Max": 2}}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
blue
green
red
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... ok (44 matches)
bisect: run: test +1-x002... FAIL (45 matches)
bisect: run: test +01-x002... ok (23 matches)
bisect: run: test +11-x002... ok (22 matches)
bisect: run: test +01+11-x002... FAIL (23 matches)
bisect: run: test +001+11-x002... ok (12 matches)
bisect: run: test +101+11-x002... FAIL (11 matches)
bisect: run: test +0101+11-x002... ok (6 matches)
bisect: run: test +1101+11-x002... ok (5 matches)
bisect: run: test +0101+11+1101-x002... FAIL (6 matches)
bisect: run: test +00101+11+1101-x002... FAIL (3 matches)
bisect: run: test +000101+11+1101-x002... FAIL (2 matches)
bisect: run: test +0000101+11+1101-x002... ok (1 matches)
bisect: run: test +1000101+11+1101-x002... FAIL (1 matches)
bisect: run: test +1101+11+x045-x002... FAIL (5 matches)
bisect: run: test +01101+11+x045-x002... FAIL (3 matches)
bisect: run: test +001101+11+x045-x002... FAIL (2 matches)
bisect: run: test +0001101+11+x045-x002... FAIL (1 matches)
bisect: run: test +11+x045+x00d-x002... FAIL (22 matches)
bisect: run: test +011+x045+x00d-x002... ok (11 matches)
bisect: run: test +111+x045+x00d-x002... FAIL (11 matches)
bisect: run: test +0111+x045+x00d-x002... FAIL (6 matches)
bisect: run: test +00111+x045+x00d-x002... FAIL (3 matches)
bisect: run: test +000111+x045+x00d-x002... ok (2 matches)
bisect: run: test +100111+x045+x00d-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x045+x00d+x027-x002... FAIL (3 matches)
bisect: FOUND failing change set


================================================
FILE: cmd/bisect/testdata/maxset.txt
================================================
{"Fail": "amber || apricot && peach || red && green && blue || cyan && magenta && yellow && black", "Bisect": {"MaxSet": 3}}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
blue
green
red
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... ok (44 matches)
bisect: run: test +1-x002... FAIL (45 matches)
bisect: run: test +01-x002... ok (23 matches)
bisect: run: test +11-x002... ok (22 matches)
bisect: run: test +01+11-x002... FAIL (23 matches)
bisect: run: test +001+11-x002... ok (12 matches)
bisect: run: test +101+11-x002... FAIL (11 matches)
bisect: run: test +0101+11-x002... ok (6 matches)
bisect: run: test +1101+11-x002... ok (5 matches)
bisect: run: test +0101+11+1101-x002... FAIL (6 matches)
bisect: run: test +00101+11+1101-x002... FAIL (3 matches)
bisect: run: test +000101+11+1101-x002... FAIL (2 matches)
bisect: run: test +0000101+11+1101-x002... ok (1 matches)
bisect: run: test +1000101+11+1101-x002... FAIL (1 matches)
bisect: run: test +1101+11+x045-x002... FAIL (5 matches)
bisect: run: test +01101+11+x045-x002... FAIL (3 matches)
bisect: run: test +001101+11+x045-x002... FAIL (2 matches)
bisect: run: test +0001101+11+x045-x002... FAIL (1 matches)
bisect: run: test +11+x045+x00d-x002... FAIL (22 matches)
bisect: run: test +011+x045+x00d-x002... ok (11 matches)
bisect: run: test +111+x045+x00d-x002... FAIL (11 matches)
bisect: run: test +0111+x045+x00d-x002... FAIL (6 matches)
bisect: run: test +00111+x045+x00d-x002... FAIL (3 matches)
bisect: run: test +000111+x045+x00d-x002... ok (2 matches)
bisect: run: test +100111+x045+x00d-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x045+x00d+x027-x002... FAIL (3 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x045-x00d-x027-x002... FAIL (86 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x045-x00d-x027-x002... ok (44 matches)
bisect: run: test +1-x045-x00d-x027-x002... ok (42 matches)
bisect: run: test +0+1-x045-x00d-x027-x002... FAIL (44 matches)
bisect: run: test +00+1-x045-x00d-x027-x002... FAIL (23 matches)
bisect: run: test +000+1-x045-x00d-x027-x002... ok (12 matches)
bisect: run: test +100+1-x045-x00d-x027-x002... ok (11 matches)
bisect: run: test +000+1+100-x045-x00d-x027-x002... FAIL (12 matches)
bisect: run: test +0000+1+100-x045-x00d-x027-x002... FAIL (6 matches)
bisect: run: test +00000+1+100-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +000000+1+100-x045-x00d-x027-x002... ok (2 matches)
bisect: run: test +100000+1+100-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +100+1+x020-x045-x00d-x027-x002... FAIL (11 matches)
bisect: run: test +0100+1+x020-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +1100+1+x020-x045-x00d-x027-x002... FAIL (5 matches)
bisect: run: test +01100+1+x020-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +001100+1+x020-x045-x00d-x027-x002... FAIL (2 matches)
bisect: run: test +0001100+1+x020-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +1+x020+x00c-x045-x00d-x027-x002... FAIL (42 matches)
bisect: run: test +01+x020+x00c-x045-x00d-x027-x002... FAIL (21 matches)
bisect: run: test +001+x020+x00c-x045-x00d-x027-x002... FAIL (12 matches)
bisect: run: test +0001+x020+x00c-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +1001+x020+x00c-x045-x00d-x027-x002... ok (6 matches)


================================================
FILE: cmd/bisect/testdata/maxset1.txt
================================================
{"Fail": "apricot && peach", "Bisect": {"MaxSet": 1}}
-- stdout --
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... ok (45 matches)
bisect: run: test +1... ok (45 matches)
bisect: fatal error: cannot find any failing change sets of size ≤ 1
<bisect failed>


================================================
FILE: cmd/bisect/testdata/maxset4.txt
================================================
{"Fail": "amber || apricot && peach || red && green && blue || cyan && magenta && yellow && black", "Bisect": {"MaxSet": 4}}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
blue
green
red
---
--- change set #3 (enabling changes causes failure)
black
cyan
magenta
yellow
---
--- change set #4 (enabling changes causes failure)
apricot
peach
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... ok (44 matches)
bisect: run: test +1-x002... FAIL (45 matches)
bisect: run: test +01-x002... ok (23 matches)
bisect: run: test +11-x002... ok (22 matches)
bisect: run: test +01+11-x002... FAIL (23 matches)
bisect: run: test +001+11-x002... ok (12 matches)
bisect: run: test +101+11-x002... FAIL (11 matches)
bisect: run: test +0101+11-x002... ok (6 matches)
bisect: run: test +1101+11-x002... ok (5 matches)
bisect: run: test +0101+11+1101-x002... FAIL (6 matches)
bisect: run: test +00101+11+1101-x002... FAIL (3 matches)
bisect: run: test +000101+11+1101-x002... FAIL (2 matches)
bisect: run: test +0000101+11+1101-x002... ok (1 matches)
bisect: run: test +1000101+11+1101-x002... FAIL (1 matches)
bisect: run: test +1101+11+x045-x002... FAIL (5 matches)
bisect: run: test +01101+11+x045-x002... FAIL (3 matches)
bisect: run: test +001101+11+x045-x002... FAIL (2 matches)
bisect: run: test +0001101+11+x045-x002... FAIL (1 matches)
bisect: run: test +11+x045+x00d-x002... FAIL (22 matches)
bisect: run: test +011+x045+x00d-x002... ok (11 matches)
bisect: run: test +111+x045+x00d-x002... FAIL (11 matches)
bisect: run: test +0111+x045+x00d-x002... FAIL (6 matches)
bisect: run: test +00111+x045+x00d-x002... FAIL (3 matches)
bisect: run: test +000111+x045+x00d-x002... ok (2 matches)
bisect: run: test +100111+x045+x00d-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x045+x00d+x027-x002... FAIL (3 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x045-x00d-x027-x002... FAIL (86 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x045-x00d-x027-x002... ok (44 matches)
bisect: run: test +1-x045-x00d-x027-x002... ok (42 matches)
bisect: run: test +0+1-x045-x00d-x027-x002... FAIL (44 matches)
bisect: run: test +00+1-x045-x00d-x027-x002... FAIL (23 matches)
bisect: run: test +000+1-x045-x00d-x027-x002... ok (12 matches)
bisect: run: test +100+1-x045-x00d-x027-x002... ok (11 matches)
bisect: run: test +000+1+100-x045-x00d-x027-x002... FAIL (12 matches)
bisect: run: test +0000+1+100-x045-x00d-x027-x002... FAIL (6 matches)
bisect: run: test +00000+1+100-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +000000+1+100-x045-x00d-x027-x002... ok (2 matches)
bisect: run: test +100000+1+100-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +100+1+x020-x045-x00d-x027-x002... FAIL (11 matches)
bisect: run: test +0100+1+x020-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +1100+1+x020-x045-x00d-x027-x002... FAIL (5 matches)
bisect: run: test +01100+1+x020-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +001100+1+x020-x045-x00d-x027-x002... FAIL (2 matches)
bisect: run: test +0001100+1+x020-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +1+x020+x00c-x045-x00d-x027-x002... FAIL (42 matches)
bisect: run: test +01+x020+x00c-x045-x00d-x027-x002... FAIL (21 matches)
bisect: run: test +001+x020+x00c-x045-x00d-x027-x002... FAIL (12 matches)
bisect: run: test +0001+x020+x00c-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +1001+x020+x00c-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +0001+x020+x00c+1001-x045-x00d-x027-x002... FAIL (6 matches)
bisect: run: test +00001+x020+x00c+1001-x045-x00d-x027-x002... ok (3 matches)
bisect: run: test +10001+x020+x00c+1001-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +010001+x020+x00c+1001-x045-x00d-x027-x002... ok (2 matches)
bisect: run: test +110001+x020+x00c+1001-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +1001+x020+x00c+x031-x045-x00d-x027-x002... FAIL (6 matches)
bisect: run: test +01001+x020+x00c+x031-x045-x00d-x027-x002... ok (3 matches)
bisect: run: test +11001+x020+x00c+x031-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +011001+x020+x00c+x031-x045-x00d-x027-x002... FAIL (2 matches)
bisect: run: test +0011001+x020+x00c+x031-x045-x00d-x027-x002... ok (1 matches)
bisect: run: test +1011001+x020+x00c+x031-x045-x00d-x027-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x020+x00c+x031+x059-x045-x00d-x027-x002... FAIL (4 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (82 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (42 matches)
bisect: run: test +1-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (40 matches)
bisect: run: test +0+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (42 matches)
bisect: run: test +00+1-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (21 matches)
bisect: run: test +10+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (21 matches)
bisect: run: test +010+1-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (10 matches)
bisect: run: test +110+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (11 matches)
bisect: run: test +0110+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (6 matches)
bisect: run: test +00110+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (3 matches)
bisect: run: test +000110+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (2 matches)
bisect: run: test +0000110+1-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (1 matches)
bisect: run: test +1+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (40 matches)
bisect: run: test +01+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (19 matches)
bisect: run: test +11+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (21 matches)
bisect: run: test +011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (11 matches)
bisect: run: test +0011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (6 matches)
bisect: run: test +1011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (5 matches)
bisect: run: test +01011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (3 matches)
bisect: run: test +11011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (2 matches)
bisect: run: test +011011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (1 matches)
bisect: run: test +111011+x006-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x006+x03b-x020-x00c-x031-x059-x045-x00d-x027-x002... FAIL (2 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x006-x03b-x020-x00c-x031-x059-x045-x00d-x027-x002... ok (80 matches)
bisect: target succeeds with all remaining changes enabled


================================================
FILE: cmd/bisect/testdata/negate.txt
================================================
{"Fail": "!amber || !apricot && !peach"}
-- stdout --
--- change set #1 (disabling changes causes failure)
amber
---
--- change set #2 (disabling changes causes failure)
apricot
peach
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... FAIL (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... ok (90 matches)
bisect: target fails with no changes, succeeds with all changes
bisect: searching for minimal set of disabled changes causing failure
bisect: run: test !+0... FAIL (45 matches)
bisect: run: test !+00... ok (23 matches)
bisect: run: test !+10... FAIL (22 matches)
bisect: run: test !+010... FAIL (11 matches)
bisect: run: test !+0010... FAIL (6 matches)
bisect: run: test !+00010... FAIL (3 matches)
bisect: run: test !+000010... FAIL (2 matches)
bisect: run: test !+0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v!+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test !-x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test !+0-x002... ok (44 matches)
bisect: run: test !+1-x002... ok (45 matches)
bisect: run: test !+0+1-x002... FAIL (44 matches)
bisect: run: test !+00+1-x002... ok (23 matches)
bisect: run: test !+10+1-x002... FAIL (21 matches)
bisect: run: test !+010+1-x002... ok (10 matches)
bisect: run: test !+110+1-x002... FAIL (11 matches)
bisect: run: test !+0110+1-x002... FAIL (6 matches)
bisect: run: test !+00110+1-x002... FAIL (3 matches)
bisect: run: test !+000110+1-x002... FAIL (2 matches)
bisect: run: test !+0000110+1-x002... FAIL (1 matches)
bisect: run: test !+1+x006-x002... FAIL (45 matches)
bisect: run: test !+01+x006-x002... ok (23 matches)
bisect: run: test !+11+x006-x002... FAIL (22 matches)
bisect: run: test !+011+x006-x002... FAIL (11 matches)
bisect: run: test !+0011+x006-x002... ok (6 matches)
bisect: run: test !+1011+x006-x002... FAIL (5 matches)
bisect: run: test !+01011+x006-x002... ok (3 matches)
bisect: run: test !+11011+x006-x002... FAIL (2 matches)
bisect: run: test !+011011+x006-x002... ok (1 matches)
bisect: run: test !+111011+x006-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v!+x006+x03b-x002... FAIL (2 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test !-x006-x03b-x002... ok (87 matches)
bisect: target succeeds with all remaining changes disabled


================================================
FILE: cmd/bisect/testdata/rand.txt
================================================
{"Fail": "amber || apricot || blue && random"}
-- stdout --
--- change set #1 (enabling changes causes failure)
amber
---
--- change set #2 (enabling changes causes failure)
apricot
---
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... FAIL (45 matches)
bisect: run: test +00... ok (23 matches)
bisect: run: test +10... FAIL (22 matches)
bisect: run: test +010... FAIL (11 matches)
bisect: run: test +0010... FAIL (6 matches)
bisect: run: test +00010... FAIL (3 matches)
bisect: run: test +000010... FAIL (2 matches)
bisect: run: test +0000010... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x002... FAIL (89 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x002... FAIL (44 matches)
bisect: run: test +00-x002... ok (23 matches)
bisect: run: test +10-x002... FAIL (21 matches)
bisect: run: test +010-x002... ok (10 matches)
bisect: run: test +110-x002... FAIL (11 matches)
bisect: run: test +0110-x002... FAIL (6 matches)
bisect: run: test +00110-x002... FAIL (3 matches)
bisect: run: test +000110-x002... FAIL (2 matches)
bisect: run: test +0000110-x002... FAIL (1 matches)
bisect: confirming failing change set
bisect: run: test v+x006-x002... FAIL (1 matches)
bisect: FOUND failing change set
bisect: checking for more failures
bisect: run: test -x006-x002... FAIL (88 matches)
bisect: target still fails; searching for more bad changes
bisect: run: test +0-x006-x002... ok (43 matches)
bisect: run: test +1-x006-x002... FAIL (45 matches)
bisect: run: test +01-x006-x002... FAIL (23 matches)
bisect: run: test +001-x006-x002... ok (12 matches)
bisect: run: test +101-x006-x002... FAIL (11 matches)
bisect: run: test +0101-x006-x002... ok (6 matches)
bisect: run: test +1101-x006-x002... FAIL (5 matches)
bisect: run: test +01101-x006-x002... ok (3 matches)
bisect: run: test +11101-x006-x002... ok (2 matches)
bisect: run: test +01101+11101-x006-x002... FAIL (3 matches)
bisect: run: test +001101+11101-x006-x002... ok (2 matches)
bisect: run: test +101101+11101-x006-x002... ok (1 matches)
bisect: run: test +001101+11101+101101-x006-x002... ok (2 matches)
bisect: fatal error: target fails inconsistently
<bisect failed>


================================================
FILE: cmd/bisect/testdata/rand1.txt
================================================
{"Fail": "blue && random"}
-- stdout --
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... ok (45 matches)
bisect: run: test +1... FAIL (45 matches)
bisect: run: test +01... FAIL (23 matches)
bisect: run: test +001... ok (12 matches)
bisect: run: test +101... FAIL (11 matches)
bisect: run: test +0101... ok (6 matches)
bisect: run: test +1101... FAIL (5 matches)
bisect: run: test +01101... ok (3 matches)
bisect: run: test +11101... ok (2 matches)
bisect: run: test +01101+11101... FAIL (3 matches)
bisect: run: test +001101+11101... ok (2 matches)
bisect: run: test +101101+11101... ok (1 matches)
bisect: run: test +001101+11101+101101... ok (2 matches)
bisect: fatal error: target fails inconsistently
<bisect failed>


================================================
FILE: cmd/bisect/testdata/rand2.txt
================================================
{"Fail": "blue && random", "Bisect": {"Count": 2}}
-- stdout --
-- stderr --
bisect: checking target with all changes disabled
bisect: run: test n... ok (90 matches)
bisect: run: test n... ok (90 matches)
bisect: checking target with all changes enabled
bisect: run: test y... FAIL (90 matches)
bisect: run: test y... FAIL (90 matches)
bisect: target succeeds with no changes, fails with all changes
bisect: searching for minimal set of enabled changes causing failure
bisect: run: test +0... ok (45 matches)
bisect: run: test +0... ok (45 matches)
bisect: run: test +1... FAIL (45 matches)
bisect: run: test +1... FAIL (45 matches)
bisect: run: test +01... FAIL (23 matches)
bisect: run: test +01... ok (23 matches)
bisect: fatal error: target fails inconsistently
<bisect failed>


================================================
FILE: cmd/bundle/.gitignore
================================================
testdata/out.got


================================================
FILE: cmd/bundle/main.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Bundle creates a single-source-file version of a source package
// suitable for inclusion in a particular target package.
//
// Usage:
//
//	bundle [-o file] [-dst path] [-pkg name] [-prefix p] [-import old=new] [-tags build_constraints] <src>
//
// The src argument specifies the import path of the package to bundle.
// The bundling of a directory of source files into a single source file
// necessarily imposes a number of constraints.
// The package being bundled must not use cgo; must not use conditional
// file compilation, whether with build tags or system-specific file names
// like code_amd64.go; must not depend on any special comments, which
// may not be preserved; must not use any assembly sources;
// must not use renaming imports; and must not use reflection-based APIs
// that depend on the specific names of types or struct fields.
//
// By default, bundle writes the bundled code to standard output.
// If the -o argument is given, bundle writes to the named file
// and also includes a “//go:generate” comment giving the exact
// command line used, for regenerating the file with “go generate.”
//
// Bundle customizes its output for inclusion in a particular package, the destination package.
// By default bundle assumes the destination is the package in the current directory,
// but the destination package can be specified explicitly using the -dst option,
// which takes an import path as its argument.
// If the source package imports the destination package, bundle will remove
// those imports and rewrite any references to use direct references to the
// corresponding symbols.
// Bundle also must write a package declaration in the output and must
// choose a name to use in that declaration.
// If the -pkg option is given, bundle uses that name.
// Otherwise, the name of the destination package is used.
// Build constraints for the generated file can be specified using the -tags option.
//
// To avoid collisions, bundle inserts a prefix at the beginning of
// every package-level const, func, type, and var identifier in src's code,
// updating references accordingly. The default prefix is the package name
// of the source package followed by an underscore. The -prefix option
// specifies an alternate prefix.
//
// Occasionally it is necessary to rewrite imports during the bundling
// process. The -import option, which may be repeated, specifies that
// an import of "old" should be rewritten to import "new" instead.
//
// # Example
//
// Bundle archive/zip for inclusion in cmd/dist:
//
//	cd $GOROOT/src/cmd/dist
//	bundle -o zip.go archive/zip
//
// Bundle golang.org/x/net/http2 for inclusion in net/http,
// prefixing all identifiers by "http2" instead of "http2_", and
// including a "!nethttpomithttp2" build constraint:
//
//	cd $GOROOT/src/net/http
//	bundle -o h2_bundle.go -prefix http2 -tags '!nethttpomithttp2' golang.org/x/net/http2
//
// Update the http2 bundle in net/http:
//
//	go generate net/http
//
// Update all bundles in the standard library:
//
//	go generate -run bundle std
package main

import (
	"bytes"
	"flag"
	"fmt"
	"go/ast"
	"go/format"
	"go/printer"
	"go/token"
	"go/types"
	"log"
	"os"
	"strconv"
	"strings"
	"unicode"

	"golang.org/x/tools/go/packages"
)

var (
	outputFile = flag.String("o", "", "write output to `file` (default standard output)")
	dstPath    = flag.String("dst", ".", "set destination import `path`")
	pkgName    = flag.String("pkg", "", "set destination package `name`")
	prefix     = flag.String("prefix", "&_", "set bundled identifier prefix to `p` (default is \"&_\", where & stands for the original name)")
	buildTags  = flag.String("tags", "", "the build constraints to be inserted into the generated file")

	importMap = map[string]string{}
)

func init() {
	flag.Var(flagFunc(addImportMap), "import", "rewrite import using `map`, of form old=new (can be repeated)")
}

func addImportMap(s string) {
	if strings.Count(s, "=") != 1 {
		log.Fatal("-import argument must be of the form old=new")
	}
	i := strings.Index(s, "=")
	old, new := s[:i], s[i+1:]
	if old == "" || new == "" {
		log.Fatal("-import argument must be of the form old=new; old and new must be non-empty")
	}
	importMap[old] = new
}

func usage() {
	fmt.Fprintf(os.Stderr, "Usage: bundle [options] <src>\n")
	flag.PrintDefaults()
}

func main() {
	log.SetPrefix("bundle: ")
	log.SetFlags(0)

	flag.Usage = usage
	flag.Parse()
	args := flag.Args()
	if len(args) != 1 {
		usage()
		os.Exit(2)
	}

	cfg := &packages.Config{Mode: packages.NeedName}
	pkgs, err := packages.Load(cfg, *dstPath)
	if err != nil {
		log.Fatalf("cannot load destination package: %v", err)
	}
	if packages.PrintErrors(pkgs) > 0 || len(pkgs) != 1 {
		log.Fatalf("failed to load destination package")
	}
	if *pkgName == "" {
		*pkgName = pkgs[0].Name
	}

	code, err := bundle(args[0], pkgs[0].PkgPath, *pkgName, *prefix, *buildTags)
	if err != nil {
		log.Fatal(err)
	}
	if *outputFile != "" {
		err := os.WriteFile(*outputFile, code, 0666)
		if err != nil {
			log.Fatal(err)
		}
	} else {
		_, err := os.Stdout.Write(code)
		if err != nil {
			log.Fatal(err)
		}
	}
}

// isStandardImportPath is copied from cmd/go in the standard library.
func isStandardImportPath(path string) bool {
	i := strings.Index(path, "/")
	if i < 0 {
		i = len(path)
	}
	elem := path[:i]
	return !strings.Contains(elem, ".")
}

var testingOnlyPackagesConfig *packages.Config

func bundle(src, dst, dstpkg, prefix, buildTags string) ([]byte, error) {
	// Load the initial package.
	cfg := &packages.Config{}
	if testingOnlyPackagesConfig != nil {
		*cfg = *testingOnlyPackagesConfig
	} else {
		// Bypass default vendor mode, as we need a package not available in the
		// std module vendor folder.
		cfg.Env = append(os.Environ(), "GOFLAGS=-mod=mod")
	}
	cfg.Mode = packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo
	pkgs, err := packages.Load(cfg, src)
	if err != nil {
		return nil, err
	}
	if packages.PrintErrors(pkgs) > 0 || len(pkgs) != 1 {
		return nil, fmt.Errorf("failed to load source package")
	}
	pkg := pkgs[0]

	if strings.Contains(prefix, "&") {
		prefix = strings.Replace(prefix, "&", pkg.Syntax[0].Name.Name, -1)
	}

	objsToUpdate := make(map[types.Object]bool)
	var rename func(from types.Object)
	rename = func(from types.Object) {
		if !objsToUpdate[from] {
			objsToUpdate[from] = true

			// Renaming a type that is used as an embedded field
			// requires renaming the field too. e.g.
			// 	type T int // if we rename this to U..
			// 	var s struct {T}
			// 	print(s.T) // ...this must change too
			if _, ok := from.(*types.TypeName); ok {
				for id, obj := range pkg.TypesInfo.Uses {
					if obj == from {
						if field := pkg.TypesInfo.Defs[id]; field != nil {
							rename(field)
						}
					}
				}
			}
		}
	}

	// Rename each package-level object.
	scope := pkg.Types.Scope()
	for _, name := range scope.Names() {
		rename(scope.Lookup(name))
	}

	var out bytes.Buffer
	if buildTags != "" {
		fmt.Fprintf(&out, "//go:build %s\n", buildTags)
	}

	fmt.Fprintf(&out, "// Code generated by golang.org/x/tools/cmd/bundle. DO NOT EDIT.\n")
	if *outputFile != "" && buildTags == "" {
		fmt.Fprintf(&out, "//go:generate bundle %s\n", strings.Join(quoteArgs(os.Args[1:]), " "))
	} else {
		fmt.Fprintf(&out, "//   $ bundle %s\n", strings.Join(os.Args[1:], " "))
	}
	fmt.Fprintf(&out, "\n")

	// Concatenate package comments from all files...
	for _, f := range pkg.Syntax {
		if doc := f.Doc.Text(); strings.TrimSpace(doc) != "" {
			for line := range strings.SplitSeq(doc, "\n") {
				fmt.Fprintf(&out, "// %s\n", line)
			}
		}
	}
	// ...but don't let them become the actual package comment.
	fmt.Fprintln(&out)

	fmt.Fprintf(&out, "package %s\n\n", dstpkg)

	// BUG(adonovan,shurcooL): bundle may generate incorrect code
	// due to shadowing between identifiers and imported package names.
	//
	// The generated code will either fail to compile or
	// (unlikely) compile successfully but have different behavior
	// than the original package. The risk of this happening is higher
	// when the original package has renamed imports (they're typically
	// renamed in order to resolve a shadow inside that particular .go file).

	// TODO(adonovan,shurcooL):
	// - detect shadowing issues, and either return error or resolve them
	// - preserve comments from the original import declarations.

	// pkgStd and pkgExt are sets of printed import specs. This is done
	// to deduplicate instances of the same import name and path.
	var pkgStd = make(map[string]bool)
	var pkgExt = make(map[string]bool)
	for _, f := range pkg.Syntax {
		for _, imp := range f.Imports {
			path, err := strconv.Unquote(imp.Path.Value)
			if err != nil {
				log.Fatalf("invalid import path string: %v", err) // Shouldn't happen here since packages.Load succeeded.
			}
			if path == dst {
				continue
			}
			if newPath, ok := importMap[path]; ok {
				path = newPath
			}

			var name string
			if imp.Name != nil {
				name = imp.Name.Name
			}
			spec := fmt.Sprintf("%s %q", name, path)
			if isStandardImportPath(path) {
				pkgStd[spec] = true
			} else {
				pkgExt[spec] = true
			}
		}
	}

	// Print a single declaration that imports all necessary packages.
	fmt.Fprintln(&out, "import (")
	for p := range pkgStd {
		fmt.Fprintf(&out, "\t%s\n", p)
	}
	if len(pkgExt) > 0 {
		fmt.Fprintln(&out)
	}
	for p := range pkgExt {
		fmt.Fprintf(&out, "\t%s\n", p)
	}
	fmt.Fprint(&out, ")\n\n")

	// Modify and print each file.
	for _, f := range pkg.Syntax {
		// Update renamed identifiers.
		for id, obj := range pkg.TypesInfo.Defs {
			if objsToUpdate[obj] {
				id.Name = prefix + obj.Name()
			}
		}
		for id, obj := range pkg.TypesInfo.Uses {
			if objsToUpdate[obj] {
				id.Name = prefix + obj.Name()
			}
		}

		// For each qualified identifier that refers to the
		// destination package, remove the qualifier.
		// The "@@@." strings are removed in postprocessing.
		ast.Inspect(f, func(n ast.Node) bool {
			if sel, ok := n.(*ast.SelectorExpr); ok {
				if id, ok := sel.X.(*ast.Ident); ok {
					if obj, ok := pkg.TypesInfo.Uses[id].(*types.PkgName); ok {
						if obj.Imported().Path() == dst {
							id.Name = "@@@"
						}
					}
				}
			}
			return true
		})

		last := f.Package
		if len(f.Imports) > 0 {
			imp := f.Imports[len(f.Imports)-1]
			last = imp.End()
			if imp.Comment != nil {
				if e := imp.Comment.End(); e > last {
					last = e
				}
			}
		}

		// Pretty-print package-level declarations.
		// but no package or import declarations.
		var buf bytes.Buffer
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT {
				continue
			}

			beg, end := sourceRange(decl)

			printComments(&out, f.Comments, last, beg)

			buf.Reset()
			format.Node(&buf, pkg.Fset, &printer.CommentedNode{Node: decl, Comments: f.Comments})
			// Remove each "@@@." in the output.
			// TODO(adonovan): not hygienic.
			out.Write(bytes.Replace(buf.Bytes(), []byte("@@@."), nil, -1))

			last = printSameLineComment(&out, f.Comments, pkg.Fset, end)

			out.WriteString("\n\n")
		}

		printLastComments(&out, f.Comments, last)
	}

	// Now format the entire thing.
	result, err := format.Source(out.Bytes())
	if err != nil {
		log.Fatalf("formatting failed: %v", err)
	}

	return result, nil
}

// sourceRange returns the [beg, end) interval of source code
// belonging to decl (incl. associated comments).
func sourceRange(decl ast.Decl) (beg, end token.Pos) {
	beg = decl.Pos()
	end = decl.End()

	var doc, com *ast.CommentGroup

	switch d := decl.(type) {
	case *ast.GenDecl:
		doc = d.Doc
		if len(d.Specs) > 0 {
			switch spec := d.Specs[len(d.Specs)-1].(type) {
			case *ast.ValueSpec:
				com = spec.Comment
			case *ast.TypeSpec:
				com = spec.Comment
			}
		}
	case *ast.FuncDecl:
		doc = d.Doc
	}

	if doc != nil {
		beg = doc.Pos()
	}
	if com != nil && com.End() > end {
		end = com.End()
	}

	return beg, end
}

func printComments(out *bytes.Buffer, comments []*ast.CommentGroup, pos, end token.Pos) {
	for _, cg := range comments {
		if pos <= cg.Pos() && cg.Pos() < end {
			for _, c := range cg.List {
				fmt.Fprintln(out, c.Text)
			}
			fmt.Fprintln(out)
		}
	}
}

const infinity = 1 << 30

func printLastComments(out *bytes.Buffer, comments []*ast.CommentGroup, pos token.Pos) {
	printComments(out, comments, pos, infinity)
}

func printSameLineComment(out *bytes.Buffer, comments []*ast.CommentGroup, fset *token.FileSet, pos token.Pos) token.Pos {
	tf := fset.File(pos)
	for _, cg := range comments {
		if pos <= cg.Pos() && tf.Line(cg.Pos()) == tf.Line(pos) {
			for _, c := range cg.List {
				fmt.Fprintln(out, c.Text)
			}
			return cg.End()
		}
	}
	return pos
}

func quoteArgs(ss []string) []string {
	// From go help generate:
	//
	// > The arguments to the directive are space-separated tokens or
	// > double-quoted strings passed to the generator as individual
	// > arguments when it is run.
	//
	// > Quoted strings use Go syntax and are evaluated before execution; a
	// > quoted string appears as a single argument to the generator.
	//
	var qs []string
	for _, s := range ss {
		if s == "" || containsSpace(s) {
			s = strconv.Quote(s)
		}
		qs = append(qs, s)
	}
	return qs
}

func containsSpace(s string) bool {
	for _, r := range s {
		if unicode.IsSpace(r) {
			return true
		}
	}
	return false
}

type flagFunc func(string)

func (f flagFunc) Set(s string) error {
	f(s)
	return nil
}

func (f flagFunc) String() string { return "" }


================================================
FILE: cmd/bundle/main_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"os"
	"os/exec"
	"runtime"
	"testing"

	"golang.org/x/tools/internal/packagestest"
)

func TestBundle(t *testing.T) { packagestest.TestAll(t, testBundle) }
func testBundle(t *testing.T, x packagestest.Exporter) {
	load := func(name string) string {
		data, err := os.ReadFile(name)
		if err != nil {
			t.Fatal(err)
		}
		return string(data)
	}

	e := packagestest.Export(t, x, []packagestest.Module{
		{
			Name: "initial",
			Files: map[string]any{
				"a.go": load("testdata/src/initial/a.go"),
				"b.go": load("testdata/src/initial/b.go"),
				"c.go": load("testdata/src/initial/c.go"),
			},
		},
		{
			Name: "domain.name/importdecl",
			Files: map[string]any{
				"p.go": load("testdata/src/domain.name/importdecl/p.go"),
			},
		},
	})
	defer e.Cleanup()
	testingOnlyPackagesConfig = e.Config

	os.Args = os.Args[:1] // avoid e.g. -test=short in the output
	out, err := bundle("initial", "github.com/dest", "dest", "prefix", "tag")
	if err != nil {
		t.Fatal(err)
	}

	if got, want := string(out), load("testdata/out.golden"); got != want {
		t.Errorf("-- got --\n%s\n-- want --\n%s\n-- diff --", got, want)

		if err := os.WriteFile("testdata/out.got", out, 0644); err != nil {
			t.Fatal(err)
		}
		t.Log(diff("testdata/out.golden", "testdata/out.got"))
	}
}

func diff(a, b string) string {
	var cmd *exec.Cmd
	switch runtime.GOOS {
	case "plan9":
		cmd = exec.Command("/bin/diff", "-c", a, b)
	default:
		cmd = exec.Command("/usr/bin/diff", "-u", a, b)
	}
	var out bytes.Buffer
	cmd.Stdout = &out
	cmd.Stderr = &out
	cmd.Run() // nonzero exit is expected
	if out.Len() == 0 {
		return "(failed to compute diff)"
	}
	return out.String()
}


================================================
FILE: cmd/bundle/testdata/out.golden
================================================
//go:build tag

// Code generated by golang.org/x/tools/cmd/bundle. DO NOT EDIT.
//   $ bundle

// The package doc comment
//

package dest

import (
	"fmt"
	. "fmt"
	_ "fmt"
	renamedfmt "fmt"
	renamedfmt2 "fmt"

	"domain.name/importdecl"
)

// init functions are not renamed
func init() { prefixfoo() }

// Type S.
type prefixS struct {
	prefixt
	u int
} /* multi-line
comment
*/

// non-associated comment

/*
	non-associated comment2
*/

// Function bar.
func prefixbar(s *prefixS) {
	fmt.Println(s.prefixt, s.u) // comment inside function
}

// file-end comment

type prefixt int // type1

// const1
const prefixc = 1 // const2

func prefixfoo() {
	fmt.Println(importdecl.F())
}

// zinit
const (
	prefixz1 = iota // z1
	prefixz2        // z2
) // zend

func prefixbaz() {
	renamedfmt.Println()
	renamedfmt2.Println()
	Println()
}


================================================
FILE: cmd/bundle/testdata/src/domain.name/importdecl/p.go
================================================
package importdecl

func F() int { return 1 }


================================================
FILE: cmd/bundle/testdata/src/initial/a.go
================================================
package initial

import "fmt" // this comment should not be visible

// init functions are not renamed
func init() { foo() }

// Type S.
type S struct {
	t
	u int
} /* multi-line
comment
*/

// non-associated comment

/*
	non-associated comment2
*/

// Function bar.
func bar(s *S) {
	fmt.Println(s.t, s.u) // comment inside function
}

// file-end comment


================================================
FILE: cmd/bundle/testdata/src/initial/b.go
================================================
// The package doc comment
package initial

import (
	"fmt"

	"domain.name/importdecl"
)

type t int // type1

// const1
const c = 1 // const2

func foo() {
	fmt.Println(importdecl.F())
}

// zinit
const (
	z1 = iota // z1
	z2        // z2
) // zend


================================================
FILE: cmd/bundle/testdata/src/initial/c.go
================================================
package initial

import _ "fmt"
import renamedfmt "fmt"
import renamedfmt2 "fmt"
import . "fmt"

func baz() {
	renamedfmt.Println()
	renamedfmt2.Println()
	Println()
}


================================================
FILE: cmd/callgraph/main.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// callgraph: a tool for reporting the call graph of a Go program.
// See Usage for details, or run with -help.
package main // import "golang.org/x/tools/cmd/callgraph"

// TODO(adonovan):
//
// Features:
// - restrict graph to a single package
// - output
//   - functions reachable from root (use digraph tool?)
//   - unreachable functions (use digraph tool?)
//   - dynamic (runtime) types
//   - indexed output (numbered nodes)
//   - JSON output
//   - additional template fields:
//     callee file/line/col

import (
	"bytes"
	"flag"
	"fmt"
	"go/token"
	"io"
	"os"
	"runtime"
	"text/template"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/callgraph/rta"
	"golang.org/x/tools/go/callgraph/static"
	"golang.org/x/tools/go/callgraph/vta"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

// flags
var (
	algoFlag = flag.String("algo", "rta",
		`Call graph construction algorithm (static, cha, rta, vta)`)

	testFlag = flag.Bool("test", false,
		"Loads test code (*_test.go) for imported packages")

	formatFlag = flag.String("format",
		"{{.Caller}}\t--{{.Dynamic}}-{{.Line}}:{{.Column}}-->\t{{.Callee}}",
		"A template expression specifying how to format an edge")

	tagsFlag = flag.String("tags", "", "comma-separated list of extra build tags (see: go help buildconstraint)")
)

const Usage = `callgraph: display the call graph of a Go program.

Usage:

  callgraph [-algo=static|cha|rta|vta] [-test] [-format=...] package...

Flags:

-algo      Specifies the call-graph construction algorithm, one of:

            static      static calls only (unsound)
            cha         Class Hierarchy Analysis
            rta         Rapid Type Analysis
            vta         Variable Type Analysis

           The algorithms are ordered by increasing precision in their
           treatment of dynamic calls (and thus also computational cost).
           RTA requires a whole program (main or test), and
           include only functions reachable from main.

-test      Include the package's tests in the analysis.

-format    Specifies the format in which each call graph edge is displayed.
           One of:

            digraph     output suitable for input to
                        golang.org/x/tools/cmd/digraph.
            graphviz    output in AT&T GraphViz (.dot) format.

           All other values are interpreted using text/template syntax.
           The default value is:

            {{.Caller}}\t--{{.Dynamic}}-{{.Line}}:{{.Column}}-->\t{{.Callee}}

           The structure passed to the template is (effectively):

                   type Edge struct {
                           Caller      *ssa.Function // calling function
                           Callee      *ssa.Function // called function

                           // Call site:
                           Filename    string // containing file
                           Offset      int    // offset within file of '('
                           Line        int    // line number
                           Column      int    // column number of call
                           Dynamic     string // "static" or "dynamic"
                           Description string // e.g. "static method call"
                   }

           Caller and Callee are *ssa.Function values, which print as
           "(*sync/atomic.Mutex).Lock", but other attributes may be
           derived from them. For example:

           - {{.Caller.Pkg.Pkg.Path}} yields the import path of the
             enclosing package; and

           - {{(.Caller.Prog.Fset.Position .Caller.Pos).Filename}}
             yields the name of the file that declares the caller.

           - The 'posn' template function returns the token.Position
             of an ssa.Function, so the previous example can be
             reduced to {{(posn .Caller).Filename}}.

           Consult the documentation for go/token, text/template, and
           golang.org/x/tools/go/ssa for more detail.

Examples:

  Show the call graph of the trivial web server application:

    callgraph -format digraph $GOROOT/src/net/http/triv.go

  Same, but show only the packages of each function:

    callgraph -format '{{.Caller.Pkg.Pkg.Path}} -> {{.Callee.Pkg.Pkg.Path}}' \
      $GOROOT/src/net/http/triv.go | sort | uniq

  Show functions that make dynamic calls into the 'fmt' test package,
  using the Rapid Type Analysis algorithm:

    callgraph -format='{{.Caller}} -{{.Dynamic}}-> {{.Callee}}' -test -algo=rta fmt |
      sed -ne 's/-dynamic-/--/p' |
      sed -ne 's/-->.*fmt_test.*$//p' | sort | uniq

  Show all functions directly called by the callgraph tool's main function:

    callgraph -format=digraph golang.org/x/tools/cmd/callgraph |
      digraph succs golang.org/x/tools/cmd/callgraph.main
`

func init() {
	// If $GOMAXPROCS isn't set, use the full capacity of the machine.
	// For small machines, use at least 4 threads.
	if os.Getenv("GOMAXPROCS") == "" {
		n := max(runtime.NumCPU(), 4)
		runtime.GOMAXPROCS(n)
	}
}

func main() {
	flag.Parse()
	if err := doCallgraph("", "", *algoFlag, *formatFlag, *testFlag, flag.Args()); err != nil {
		fmt.Fprintf(os.Stderr, "callgraph: %s\n", err)
		os.Exit(1)
	}
}

var stdout io.Writer = os.Stdout

func doCallgraph(dir, gopath, algo, format string, tests bool, args []string) error {
	if len(args) == 0 {
		fmt.Fprint(os.Stderr, Usage)
		return nil
	}

	cfg := &packages.Config{
		Mode:       packages.LoadAllSyntax,
		BuildFlags: []string{"-tags=" + *tagsFlag},
		Tests:      tests,
		Dir:        dir,
	}
	if gopath != "" {
		cfg.Env = append(os.Environ(), "GOPATH="+gopath) // to enable testing
	}
	initial, err := packages.Load(cfg, args...)
	if err != nil {
		return err
	}
	if packages.PrintErrors(initial) > 0 {
		return fmt.Errorf("packages contain errors")
	}

	// Create and build SSA-form program representation.
	mode := ssa.InstantiateGenerics // instantiate generics by default for soundness
	prog, pkgs := ssautil.AllPackages(initial, mode)
	prog.Build()

	// -- call graph construction ------------------------------------------

	var cg *callgraph.Graph

	switch algo {
	case "static":
		cg = static.CallGraph(prog)

	case "cha":
		cg = cha.CallGraph(prog)

	case "pta":
		return fmt.Errorf("pointer analysis is no longer supported (see Go issue #59676)")

	case "rta":
		mains, err := mainPackages(pkgs)
		if err != nil {
			return err
		}
		var roots []*ssa.Function
		for _, main := range mains {
			roots = append(roots, main.Func("init"), main.Func("main"))
		}
		rtares := rta.Analyze(roots, true)
		cg = rtares.CallGraph

		// NB: RTA gives us Reachable and RuntimeTypes too.

	case "vta":
		cg = vta.CallGraph(ssautil.AllFunctions(prog), nil)

	default:
		return fmt.Errorf("unknown algorithm: %s", algo)
	}

	cg.DeleteSyntheticNodes()

	// -- output------------------------------------------------------------

	var before, after string

	// Pre-canned formats.
	switch format {
	case "digraph":
		format = `{{printf "%q %q" .Caller .Callee}}`

	case "graphviz":
		before = "digraph callgraph {\n"
		after = "}\n"
		format = `  {{printf "%q" .Caller}} -> {{printf "%q" .Callee}}`
	}

	funcMap := template.FuncMap{
		"posn": func(f *ssa.Function) token.Position {
			return f.Prog.Fset.Position(f.Pos())
		},
	}
	tmpl, err := template.New("-format").Funcs(funcMap).Parse(format)
	if err != nil {
		return fmt.Errorf("invalid -format template: %v", err)
	}

	// Allocate these once, outside the traversal.
	var buf bytes.Buffer
	data := Edge{fset: prog.Fset}

	fmt.Fprint(stdout, before)
	if err := callgraph.GraphVisitEdges(cg, func(edge *callgraph.Edge) error {
		data.position.Offset = -1
		data.edge = edge
		data.Caller = edge.Caller.Func
		data.Callee = edge.Callee.Func

		buf.Reset()
		if err := tmpl.Execute(&buf, &data); err != nil {
			return err
		}
		stdout.Write(buf.Bytes())
		if len := buf.Len(); len == 0 || buf.Bytes()[len-1] != '\n' {
			fmt.Fprintln(stdout)
		}
		return nil
	}); err != nil {
		return err
	}
	fmt.Fprint(stdout, after)
	return nil
}

// mainPackages returns the main packages to analyze.
// Each resulting package is named "main" and has a main function.
func mainPackages(pkgs []*ssa.Package) ([]*ssa.Package, error) {
	var mains []*ssa.Package
	for _, p := range pkgs {
		if p != nil && p.Pkg.Name() == "main" && p.Func("main") != nil {
			mains = append(mains, p)
		}
	}
	if len(mains) == 0 {
		return nil, fmt.Errorf("no main packages")
	}
	return mains, nil
}

type Edge struct {
	Caller *ssa.Function
	Callee *ssa.Function

	edge     *callgraph.Edge
	fset     *token.FileSet
	position token.Position // initialized lazily
}

func (e *Edge) pos() *token.Position {
	if e.position.Offset == -1 {
		e.position = e.fset.Position(e.edge.Pos()) // called lazily
	}
	return &e.position
}

func (e *Edge) Filename() string { return e.pos().Filename }
func (e *Edge) Column() int      { return e.pos().Column }
func (e *Edge) Line() int        { return e.pos().Line }
func (e *Edge) Offset() int      { return e.pos().Offset }

func (e *Edge) Dynamic() string {
	if e.edge.Site != nil && e.edge.Site.Common().StaticCallee() == nil {
		return "dynamic"
	}
	return "static"
}

func (e *Edge) Description() string { return e.edge.Description() }


================================================
FILE: cmd/callgraph/main_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android && go1.11

package main

import (
	"bytes"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func init() {
	// This test currently requires GOPATH mode.
	// Explicitly disabling module mode should suffix, but
	// we'll also turn off GOPROXY just for good measure.
	if err := os.Setenv("GO111MODULE", "off"); err != nil {
		log.Fatal(err)
	}
	if err := os.Setenv("GOPROXY", "off"); err != nil {
		log.Fatal(err)
	}
}

func TestCallgraph(t *testing.T) {
	testenv.NeedsTool(t, "go")

	gopath, err := filepath.Abs("testdata")
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		algo  string
		tests bool
		want  []string
	}{
		{"rta", false, []string{
			// rta imprecisely shows cross product of {main,main2} x {C,D}
			`pkg.main --> (pkg.C).f`,
			`pkg.main --> (pkg.D).f`,
			`pkg.main --> pkg.main2`,
			`pkg.main2 --> (pkg.C).f`,
			`pkg.main2 --> (pkg.D).f`,
		}},
		{"vta", false, []string{
			// vta distinguishes main->C, main2->D.
			"pkg.main --> (pkg.C).f",
			"pkg.main --> pkg.main2",
			"pkg.main2 --> (pkg.D).f",
		}},
		// tests: both the package's main and the test's main are called.
		// The callgraph includes all the guts of the "testing" package.
		{"rta", true, []string{
			`pkg.test.main --> testing.MainStart`,
			`testing.runExample --> pkg.Example`,
			`pkg.Example --> (pkg.C).f`,
			`pkg.main --> (pkg.C).f`,
		}},
		{"vta", true, []string{
			`pkg.test.main --> testing.MainStart`,
			`testing.runExample --> pkg.Example`,
			`pkg.Example --> (pkg.C).f`,
			`pkg.main --> (pkg.C).f`,
		}},
	} {
		const format = "{{.Caller}} --> {{.Callee}}"
		stdout = new(bytes.Buffer)
		if err := doCallgraph("testdata/src", gopath, test.algo, format, test.tests, []string{"pkg"}); err != nil {
			t.Error(err)
			continue
		}

		edges := make(map[string]bool)
		for _, line := range strings.Split(fmt.Sprint(stdout), "\n") {
			edges[line] = true
		}
		ok := true
		for _, edge := range test.want {
			if !edges[edge] {
				ok = false
				t.Errorf("callgraph(%q, %t): missing edge: %s",
					test.algo, test.tests, edge)
			}
		}
		if !ok {
			t.Log("got:\n", stdout)
		}
	}
}


================================================
FILE: cmd/callgraph/testdata/src/pkg/pkg.go
================================================
package main

type I interface {
	f()
}

type C int

func (C) f() {}

type D int

func (D) f() {}

func main() {
	var i I = C(0)
	i.f() // dynamic call

	main2()
}

func main2() {
	var i I = D(0)
	i.f() // dynamic call
}


================================================
FILE: cmd/callgraph/testdata/src/pkg/pkg_test.go
================================================
package main

// An Example function must have an "Output:" comment for the go build
// system to generate a call to it from the test main package.

func Example() {
	C(0).f()

	// Output:
}


================================================
FILE: cmd/compilebench/main.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Compilebench benchmarks the speed of the Go compiler.
//
// Usage:
//
//	compilebench [options]
//
// It times the compilation of various packages and prints results in
// the format used by package testing (and expected by golang.org/x/perf/cmd/benchstat).
//
// The options are:
//
//	-alloc
//		Report allocations.
//
//	-compile exe
//		Use exe as the path to the cmd/compile binary.
//
//	-compileflags 'list'
//		Pass the space-separated list of flags to the compilation.
//
//	-link exe
//		Use exe as the path to the cmd/link binary.
//
//	-linkflags 'list'
//		Pass the space-separated list of flags to the linker.
//
//	-count n
//		Run each benchmark n times (default 1).
//
//	-cpuprofile file
//		Write a CPU profile of the compiler to file.
//
//	-go path
//		Path to "go" command (default "go").
//
//	-memprofile file
//		Write a memory profile of the compiler to file.
//
//	-memprofilerate rate
//		Set runtime.MemProfileRate during compilation.
//
//	-obj
//		Report object file statistics.
//
//	-pkg pkg
//		Benchmark compiling a single package.
//
//	-run regexp
//		Only run benchmarks with names matching regexp.
//
//	-short
//		Skip long-running benchmarks.
//
// Although -cpuprofile and -memprofile are intended to write a
// combined profile for all the executed benchmarks to file,
// today they write only the profile for the last benchmark executed.
//
// The default memory profiling rate is one profile sample per 512 kB
// allocated (see “go doc runtime.MemProfileRate”).
// Lowering the rate (for example, -memprofilerate 64000) produces
// a more fine-grained and therefore accurate profile, but it also incurs
// execution cost. For benchmark comparisons, never use timings
// obtained with a low -memprofilerate option.
//
// # Example
//
// Assuming the base version of the compiler has been saved with
// “toolstash save,” this sequence compares the old and new compiler:
//
//	compilebench -count 10 -compile $(toolstash -n compile) >old.txt
//	compilebench -count 10 >new.txt
//	benchstat old.txt new.txt
package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"time"
)

var (
	goroot                   string
	compiler                 string
	assembler                string
	linker                   string
	runRE                    *regexp.Regexp
	is6g                     bool
	needCompilingRuntimeFlag bool
)

var (
	flagGoCmd          = flag.String("go", "go", "path to \"go\" command")
	flagAlloc          = flag.Bool("alloc", false, "report allocations")
	flagObj            = flag.Bool("obj", false, "report object file stats")
	flagCompiler       = flag.String("compile", "", "use `exe` as the cmd/compile binary")
	flagAssembler      = flag.String("asm", "", "use `exe` as the cmd/asm binary")
	flagCompilerFlags  = flag.String("compileflags", "", "additional `flags` to pass to compile")
	flagLinker         = flag.String("link", "", "use `exe` as the cmd/link binary")
	flagLinkerFlags    = flag.String("linkflags", "", "additional `flags` to pass to link")
	flagRun            = flag.String("run", "", "run benchmarks matching `regexp`")
	flagCount          = flag.Int("count", 1, "run benchmarks `n` times")
	flagCpuprofile     = flag.String("cpuprofile", "", "write CPU profile to `file`")
	flagMemprofile     = flag.String("memprofile", "", "write memory profile to `file`")
	flagMemprofilerate = flag.Int64("memprofilerate", -1, "set memory profile `rate`")
	flagPackage        = flag.String("pkg", "", "if set, benchmark the package at path `pkg`")
	flagShort          = flag.Bool("short", false, "skip long-running benchmarks")
	flagTrace          = flag.Bool("trace", false, "debug tracing of builds")
)

type test struct {
	name string
	r    runner
}

type runner interface {
	long() bool
	run(name string, count int) error
}

var tests = []test{
	{"BenchmarkTemplate", compile{"html/template"}},
	{"BenchmarkUnicode", compile{"unicode"}},
	{"BenchmarkGoTypes", compile{"go/types"}},
	{"BenchmarkCompiler", compile{"cmd/compile/internal/gc"}},
	{"BenchmarkSSA", compile{"cmd/compile/internal/ssa"}},
	{"BenchmarkFlate", compile{"compress/flate"}},
	{"BenchmarkGoParser", compile{"go/parser"}},
	{"BenchmarkReflect", compile{"reflect"}},
	{"BenchmarkTar", compile{"archive/tar"}},
	{"BenchmarkXML", compile{"encoding/xml"}},
	{"BenchmarkLinkCompiler", link{"cmd/compile", ""}},
	{"BenchmarkExternalLinkCompiler", link{"cmd/compile", "-linkmode=external"}},
	{"BenchmarkLinkWithoutDebugCompiler", link{"cmd/compile", "-w"}},
	{"BenchmarkStdCmd", goBuild{[]string{"std", "cmd"}}},
	{"BenchmarkHelloSize", size{"$GOROOT/test/helloworld.go", false}},
	{"BenchmarkCmdGoSize", size{"cmd/go", true}},
}

func usage() {
	fmt.Fprintf(os.Stderr, "usage: compilebench [options]\n")
	fmt.Fprintf(os.Stderr, "options:\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("compilebench: ")
	flag.Usage = usage
	flag.Parse()
	if flag.NArg() != 0 {
		usage()
	}

	s, err := exec.Command(*flagGoCmd, "env", "GOROOT").CombinedOutput()
	if err != nil {
		log.Fatalf("%s env GOROOT: %v", *flagGoCmd, err)
	}
	goroot = strings.TrimSpace(string(s))
	os.Setenv("GOROOT", goroot) // for any subcommands

	compiler = *flagCompiler
	if compiler == "" {
		var foundTool string
		foundTool, compiler = toolPath("compile", "6g")
		if foundTool == "6g" {
			is6g = true
		}
	}
	assembler = *flagAssembler
	if assembler == "" {
		_, assembler = toolPath("asm")
	}
	if err := checkCompilingRuntimeFlag(assembler); err != nil {
		log.Fatalf("checkCompilingRuntimeFlag: %v", err)
	}

	linker = *flagLinker
	if linker == "" && !is6g { // TODO: Support 6l
		_, linker = toolPath("link")
	}

	if is6g {
		*flagMemprofilerate = -1
		*flagAlloc = false
		*flagCpuprofile = ""
		*flagMemprofile = ""
	}

	if *flagRun != "" {
		r, err := regexp.Compile(*flagRun)
		if err != nil {
			log.Fatalf("invalid -run argument: %v", err)
		}
		runRE = r
	}

	if *flagPackage != "" {
		tests = []test{
			{"BenchmarkPkg", compile{*flagPackage}},
			{"BenchmarkPkgLink", link{*flagPackage, ""}},
		}
		runRE = nil
	}

	for i := 0; i < *flagCount; i++ {
		for _, tt := range tests {
			if tt.r.long() && *flagShort {
				continue
			}
			if runRE == nil || runRE.MatchString(tt.name) {
				if err := tt.r.run(tt.name, i); err != nil {
					log.Printf("%s: %v", tt.name, err)
				}
			}
		}
	}
}

func toolPath(names ...string) (found, path string) {
	var out1 []byte
	var err1 error
	for i, name := range names {
		out, err := exec.Command(*flagGoCmd, "tool", "-n", name).CombinedOutput()
		if err == nil {
			return name, strings.TrimSpace(string(out))
		}
		if i == 0 {
			out1, err1 = out, err
		}
	}
	log.Fatalf("go tool -n %s: %v\n%s", names[0], err1, out1)
	return "", ""
}

type Pkg struct {
	ImportPath string
	Dir        string
	GoFiles    []string
	SFiles     []string
}

func goList(dir string) (*Pkg, error) {
	var pkg Pkg
	out, err := exec.Command(*flagGoCmd, "list", "-json", dir).Output()
	if err != nil {
		return nil, fmt.Errorf("go list -json %s: %v", dir, err)
	}
	if err := json.Unmarshal(out, &pkg); err != nil {
		return nil, fmt.Errorf("go list -json %s: unmarshal: %v", dir, err)
	}
	return &pkg, nil
}

func runCmd(name string, cmd *exec.Cmd) error {
	start := time.Now()
	out, err := cmd.CombinedOutput()
	if err != nil {
		return fmt.Errorf("%v\n%s", err, out)
	}
	fmt.Printf("%s 1 %d ns/op\n", name, time.Since(start).Nanoseconds())
	return nil
}

type goBuild struct{ pkgs []string }

func (goBuild) long() bool { return true }

func (r goBuild) run(name string, count int) error {
	args := []string{"build", "-a"}
	if *flagCompilerFlags != "" {
		args = append(args, "-gcflags", *flagCompilerFlags)
	}
	args = append(args, r.pkgs...)
	cmd := exec.Command(*flagGoCmd, args...)
	cmd.Dir = filepath.Join(goroot, "src")
	return runCmd(name, cmd)
}

type size struct {
	// path is either a path to a file ("$GOROOT/test/helloworld.go") or a package path ("cmd/go").
	path   string
	isLong bool
}

func (r size) long() bool { return r.isLong }

func (r size) run(name string, count int) error {
	if strings.HasPrefix(r.path, "$GOROOT/") {
		r.path = goroot + "/" + r.path[len("$GOROOT/"):]
	}

	cmd := exec.Command(*flagGoCmd, "build", "-o", "_compilebenchout_", r.path)
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		return err
	}
	defer os.Remove("_compilebenchout_")
	info, err := os.Stat("_compilebenchout_")
	if err != nil {
		return err
	}
	out, err := exec.Command("size", "_compilebenchout_").CombinedOutput()
	if err != nil {
		return fmt.Errorf("size: %v\n%s", err, out)
	}
	lines := strings.Split(string(out), "\n")
	if len(lines) < 2 {
		return fmt.Errorf("not enough output from size: %s", out)
	}
	f := strings.Fields(lines[1])
	if strings.HasPrefix(lines[0], "__TEXT") && len(f) >= 2 { // OS X
		fmt.Printf("%s 1 %s text-bytes %s data-bytes %v exe-bytes\n", name, f[0], f[1], info.Size())
	} else if strings.Contains(lines[0], "bss") && len(f) >= 3 {
		fmt.Printf("%s 1 %s text-bytes %s data-bytes %s bss-bytes %v exe-bytes\n", name, f[0], f[1], f[2], info.Size())
	}
	return nil
}

type compile struct{ dir string }

func (compile) long() bool { return false }

func (c compile) run(name string, count int) error {
	// Make sure dependencies needed by go tool compile are built.
	out, err := exec.Command(*flagGoCmd, "build", c.dir).CombinedOutput()
	if err != nil {
		return fmt.Errorf("go build %s: %v\n%s", c.dir, err, out)
	}

	// Find dir and source file list.
	pkg, err := goList(c.dir)
	if err != nil {
		return err
	}

	importcfg, err := genImportcfgFile(c.dir, "", false) // TODO: pass compiler flags?
	if err != nil {
		return err
	}

	// If this package has assembly files, we'll need to pass a symabis
	// file to the compiler; call a helper to invoke the assembler
	// to do that.
	var symAbisFile string
	var asmIncFile string
	if len(pkg.SFiles) != 0 {
		symAbisFile = filepath.Join(pkg.Dir, "symabis")
		asmIncFile = filepath.Join(pkg.Dir, "go_asm.h")
		content := "\n"
		if err := os.WriteFile(asmIncFile, []byte(content), 0666); err != nil {
			return fmt.Errorf("os.WriteFile(%s) failed: %v", asmIncFile, err)
		}
		defer os.Remove(symAbisFile)
		defer os.Remove(asmIncFile)
		if err := genSymAbisFile(pkg, symAbisFile, pkg.Dir); err != nil {
			return err
		}
	}

	args := []string{"-o", "_compilebench_.o", "-p", pkg.ImportPath}
	args = append(args, strings.Fields(*flagCompilerFlags)...)
	if symAbisFile != "" {
		args = append(args, "-symabis", symAbisFile)
	}
	if importcfg != "" {
		args = append(args, "-importcfg", importcfg)
		defer os.Remove(importcfg)
	}
	args = append(args, pkg.GoFiles...)
	if err := runBuildCmd(name, count, pkg.Dir, compiler, args); err != nil {
		return err
	}

	opath := pkg.Dir + "/_compilebench_.o"
	if *flagObj {
		// TODO(josharian): object files are big; just read enough to find what we seek.
		data, err := os.ReadFile(opath)
		if err != nil {
			log.Print(err)
		}
		// Find start of export data.
		i := bytes.Index(data, []byte("\n$$B\n")) + len("\n$$B\n")
		// Count bytes to end of export data.
		nexport := bytes.Index(data[i:], []byte("\n$$\n"))
		fmt.Printf(" %d object-bytes %d export-bytes", len(data), nexport)
	}
	fmt.Println()

	os.Remove(opath)
	return nil
}

type link struct{ dir, flags string }

func (link) long() bool { return false }

func (r link) run(name string, count int) error {
	if linker == "" {
		// No linker. Skip the test.
		return nil
	}

	// Build dependencies.
	ldflags := *flagLinkerFlags
	if r.flags != "" {
		if ldflags != "" {
			ldflags += " "
		}
		ldflags += r.flags
	}
	out, err := exec.Command(*flagGoCmd, "build", "-o", "/dev/null", "-ldflags="+ldflags, r.dir).CombinedOutput()
	if err != nil {
		return fmt.Errorf("go build -a %s: %v\n%s", r.dir, err, out)
	}

	importcfg, err := genImportcfgFile(r.dir, "-ldflags="+ldflags, true)
	if err != nil {
		return err
	}
	defer os.Remove(importcfg)

	// Build the main package.
	pkg, err := goList(r.dir)
	if err != nil {
		return err
	}
	args := []string{"-o", "_compilebench_.o", "-importcfg", importcfg}
	args = append(args, pkg.GoFiles...)
	if *flagTrace {
		fmt.Fprintf(os.Stderr, "running: %s %+v\n",
			compiler, args)
	}
	cmd := exec.Command(compiler, args...)
	cmd.Dir = pkg.Dir
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	err = cmd.Run()
	if err != nil {
		return fmt.Errorf("compiling: %v", err)
	}
	defer os.Remove(pkg.Dir + "/_compilebench_.o")

	// Link the main package.
	args = []string{"-o", "_compilebench_.exe", "-importcfg", importcfg}
	args = append(args, strings.Fields(*flagLinkerFlags)...)
	args = append(args, strings.Fields(r.flags)...)
	args = append(args, "_compilebench_.o")
	if err := runBuildCmd(name, count, pkg.Dir, linker, args); err != nil {
		return err
	}
	fmt.Println()
	defer os.Remove(pkg.Dir + "/_compilebench_.exe")

	return err
}

// runBuildCmd runs "tool args..." in dir, measures standard build
// tool metrics, and prints a benchmark line. The caller may print
// additional metrics and then must print a newline.
//
// This assumes tool accepts standard build tool flags like
// -memprofilerate, -memprofile, and -cpuprofile.
func runBuildCmd(name string, count int, dir, tool string, args []string) error {
	var preArgs []string
	if *flagMemprofilerate >= 0 {
		preArgs = append(preArgs, "-memprofilerate", fmt.Sprint(*flagMemprofilerate))
	}
	if *flagAlloc || *flagCpuprofile != "" || *flagMemprofile != "" {
		if *flagAlloc || *flagMemprofile != "" {
			preArgs = append(preArgs, "-memprofile", "_compilebench_.memprof")
		}
		if *flagCpuprofile != "" {
			preArgs = append(preArgs, "-cpuprofile", "_compilebench_.cpuprof")
		}
	}
	if *flagTrace {
		fmt.Fprintf(os.Stderr, "running: %s %+v\n",
			tool, append(preArgs, args...))
	}
	cmd := exec.Command(tool, append(preArgs, args...)...)
	cmd.Dir = dir
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	start := time.Now()
	err := cmd.Run()
	if err != nil {
		return err
	}
	end := time.Now()

	haveAllocs, haveRSS := false, false
	var allocs, allocbytes, rssbytes int64
	if *flagAlloc || *flagMemprofile != "" {
		out, err := os.ReadFile(dir + "/_compilebench_.memprof")
		if err != nil {
			log.Print("cannot find memory profile after compilation")
		}
		for line := range strings.SplitSeq(string(out), "\n") {
			f := strings.Fields(line)
			if len(f) < 4 || f[0] != "#" || f[2] != "=" {
				continue
			}
			val, err := strconv.ParseInt(f[3], 0, 64)
			if err != nil {
				continue
			}
			haveAllocs = true
			switch f[1] {
			case "TotalAlloc":
				allocbytes = val
			case "Mallocs":
				allocs = val
			case "MaxRSS":
				haveRSS = true
				rssbytes = val
			}
		}
		if !haveAllocs {
			log.Println("missing stats in memprof (golang.org/issue/18641)")
		}

		if *flagMemprofile != "" {
			outpath := *flagMemprofile
			if *flagCount != 1 {
				outpath = fmt.Sprintf("%s_%d", outpath, count)
			}
			if err := os.WriteFile(outpath, out, 0666); err != nil {
				log.Print(err)
			}
		}
		os.Remove(dir + "/_compilebench_.memprof")
	}

	if *flagCpuprofile != "" {
		out, err := os.ReadFile(dir + "/_compilebench_.cpuprof")
		if err != nil {
			log.Print(err)
		}
		outpath := *flagCpuprofile
		if *flagCount != 1 {
			outpath = fmt.Sprintf("%s_%d", outpath, count)
		}
		if err := os.WriteFile(outpath, out, 0666); err != nil {
			log.Print(err)
		}
		os.Remove(dir + "/_compilebench_.cpuprof")
	}

	wallns := end.Sub(start).Nanoseconds()
	userns := cmd.ProcessState.UserTime().Nanoseconds()

	fmt.Printf("%s 1 %d ns/op %d user-ns/op", name, wallns, userns)
	if haveAllocs {
		fmt.Printf(" %d B/op %d allocs/op", allocbytes, allocs)
	}
	if haveRSS {
		fmt.Printf(" %d maxRSS/op", rssbytes)
	}

	return nil
}

func checkCompilingRuntimeFlag(assembler string) error {
	td, err := os.MkdirTemp("", "asmsrcd")
	if err != nil {
		return fmt.Errorf("MkdirTemp failed: %v", err)
	}
	defer os.RemoveAll(td)
	src := filepath.Join(td, "asm.s")
	obj := filepath.Join(td, "asm.o")
	const code = `
TEXT ·foo(SB),$0-0
RET
`
	if err := os.WriteFile(src, []byte(code), 0644); err != nil {
		return fmt.Errorf("writing %s failed: %v", src, err)
	}

	// Try compiling the assembly source file passing
	// -compiling-runtime; if it succeeds, then we'll need it
	// when doing assembly of the reflect package later on.
	// If it does not succeed, the assumption is that it's not
	// needed.
	args := []string{"-o", obj, "-p", "reflect", "-compiling-runtime", src}
	cmd := exec.Command(assembler, args...)
	cmd.Dir = td
	out, aerr := cmd.CombinedOutput()
	if aerr != nil {
		if strings.Contains(string(out), "flag provided but not defined: -compiling-runtime") {
			// flag not defined: assume we're using a recent assembler, so
			// don't use -compiling-runtime.
			return nil
		}
		// error is not flag-related; report it.
		return fmt.Errorf("problems invoking assembler with args %+v: error %v\n%s\n", args, aerr, out)
	}
	// asm invocation succeeded -- assume we need the flag.
	needCompilingRuntimeFlag = true
	return nil
}

// genSymAbisFile runs the assembler on the target package asm files
// with "-gensymabis" to produce a symabis file that will feed into
// the Go source compilation. This is fairly hacky in that if the
// asm invocation convention changes it will need to be updated
// (hopefully that will not be needed too frequently).
func genSymAbisFile(pkg *Pkg, symAbisFile, incdir string) error {
	args := []string{"-gensymabis", "-o", symAbisFile,
		"-p", pkg.ImportPath,
		"-I", filepath.Join(goroot, "pkg", "include"),
		"-I", incdir,
		"-D", "GOOS_" + runtime.GOOS,
		"-D", "GOARCH_" + runtime.GOARCH}
	if pkg.ImportPath == "reflect" && needCompilingRuntimeFlag {
		args = append(args, "-compiling-runtime")
	}
	args = append(args, pkg.SFiles...)
	if *flagTrace {
		fmt.Fprintf(os.Stderr, "running: %s %+v\n",
			assembler, args)
	}
	cmd := exec.Command(assembler, args...)
	cmd.Dir = pkg.Dir
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	err := cmd.Run()
	if err != nil {
		return fmt.Errorf("assembling to produce symabis file: %v", err)
	}
	return nil
}

// genImportcfgFile generates an importcfg file for building package
// dir. Returns the generated importcfg file path (or empty string
// if the package has no dependency).
func genImportcfgFile(dir string, flags string, full bool) (string, error) {
	need := "{{.Imports}}"
	if full {
		// for linking, we need transitive dependencies
		need = "{{.Deps}}"
	}

	if flags == "" {
		flags = "--" // passing "" to go list, it will match to the current directory
	}

	// find imported/dependent packages
	cmd := exec.Command(*flagGoCmd, "list", "-f", need, flags, dir)
	cmd.Stderr = os.Stderr
	out, err := cmd.Output()
	if err != nil {
		return "", fmt.Errorf("go list -f %s %s: %v", need, dir, err)
	}
	// trim [ ]\n
	if len(out) < 3 || out[0] != '[' || out[len(out)-2] != ']' || out[len(out)-1] != '\n' {
		return "", fmt.Errorf("unexpected output from go list -f %s %s: %s", need, dir, out)
	}
	out = out[1 : len(out)-2]
	if len(out) == 0 {
		return "", nil
	}

	// build importcfg for imported packages
	cmd = exec.Command(*flagGoCmd, "list", "-export", "-f", "{{if .Export}}packagefile {{.ImportPath}}={{.Export}}{{end}}", flags)
	cmd.Args = append(cmd.Args, strings.Fields(string(out))...)
	cmd.Stderr = os.Stderr
	out, err = cmd.Output()
	if err != nil {
		return "", fmt.Errorf("generating importcfg for %s: %s: %v", dir, cmd, err)
	}

	f, err := os.CreateTemp("", "importcfg")
	if err != nil {
		return "", fmt.Errorf("creating tmp importcfg file failed: %v", err)
	}
	defer f.Close()
	if _, err := f.Write(out); err != nil {
		return "", fmt.Errorf("writing importcfg file %s failed: %v", f.Name(), err)
	}
	return f.Name(), nil
}


================================================
FILE: cmd/deadcode/deadcode.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	_ "embed"
	"encoding/json"
	"flag"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"io"
	"log"
	"maps"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"runtime/pprof"
	"slices"
	"sort"
	"strings"
	"text/template"

	"golang.org/x/telemetry"
	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/rta"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

// flags
var (
	testFlag = flag.Bool("test", false, "include implicit test packages and executables")
	tagsFlag = flag.String("tags", "", "comma-separated list of extra build tags (see: go help buildconstraint)")

	filterFlag    = flag.String("filter", "<module>", "report only packages matching this regular expression (default: module of first package)")
	generatedFlag = flag.Bool("generated", false, "include dead functions in generated Go files")
	whyLiveFlag   = flag.String("whylive", "", "show a path from main to the named function")
	formatFlag    = flag.String("f", "", "format output records using template")
	jsonFlag      = flag.Bool("json", false, "output JSON records")
	cpuProfile    = flag.String("cpuprofile", "", "write CPU profile to this file")
	memProfile    = flag.String("memprofile", "", "write memory profile to this file")
)

func usage() {
	// Extract the content of the /* ... */ comment in doc.go.
	_, after, _ := strings.Cut(doc, "/*\n")
	doc, _, _ := strings.Cut(after, "*/")
	io.WriteString(flag.CommandLine.Output(), doc+`
Flags:

`)
	flag.PrintDefaults()
}

func main() {
	telemetry.Start(telemetry.Config{ReportCrashes: true})

	log.SetPrefix("deadcode: ")
	log.SetFlags(0) // no time prefix

	flag.Usage = usage
	flag.Parse()
	if len(flag.Args()) == 0 {
		usage()
		os.Exit(2)
	}

	if *cpuProfile != "" {
		f, err := os.Create(*cpuProfile)
		if err != nil {
			log.Fatal(err)
		}
		if err := pprof.StartCPUProfile(f); err != nil {
			log.Fatal(err)
		}
		// NB: profile won't be written in case of error.
		defer pprof.StopCPUProfile()
	}

	if *memProfile != "" {
		f, err := os.Create(*memProfile)
		if err != nil {
			log.Fatal(err)
		}
		// NB: profile won't be written in case of error.
		defer func() {
			runtime.GC() // get up-to-date statistics
			if err := pprof.WriteHeapProfile(f); err != nil {
				log.Fatalf("Writing memory profile: %v", err)
			}
			f.Close()
		}()
	}

	// Reject bad output options early.
	if *formatFlag != "" {
		if *jsonFlag {
			log.Fatalf("you cannot specify both -f=template and -json")
		}
		if _, err := template.New("deadcode").Parse(*formatFlag); err != nil {
			log.Fatalf("invalid -f: %v", err)
		}
	}

	// Load, parse, and type-check the complete program(s).
	cfg := &packages.Config{
		BuildFlags: []string{"-tags=" + *tagsFlag},
		Mode:       packages.LoadAllSyntax | packages.NeedModule,
		Tests:      *testFlag,
	}
	initial, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		log.Fatalf("Load: %v", err)
	}
	if len(initial) == 0 {
		log.Fatalf("no packages")
	}
	if packages.PrintErrors(initial) > 0 {
		log.Fatalf("packages contain errors")
	}

	// If -filter is unset, use first module (if available).
	if *filterFlag == "<module>" {
		seen := make(map[string]bool)
		var patterns []string
		for _, pkg := range initial {
			if pkg.Module != nil && pkg.Module.Path != "" && !seen[pkg.Module.Path] {
				seen[pkg.Module.Path] = true
				patterns = append(patterns, regexp.QuoteMeta(pkg.Module.Path))
			}
		}

		if patterns != nil {
			*filterFlag = "^(" + strings.Join(patterns, "|") + ")\\b"
		} else {
			*filterFlag = "" // match any
		}
	}
	filter, err := regexp.Compile(*filterFlag)
	if err != nil {
		log.Fatalf("-filter: %v", err)
	}

	// Create SSA-form program representation
	// and find main packages.
	prog, pkgs := ssautil.AllPackages(initial, ssa.InstantiateGenerics)
	prog.Build()

	mains := ssautil.MainPackages(pkgs)
	if len(mains) == 0 {
		log.Fatalf("no main packages")
	}
	var roots []*ssa.Function
	for _, main := range mains {
		roots = append(roots, main.Func("init"), main.Func("main"))
	}

	// Gather all source-level functions,
	// as the user interface is expressed in terms of them.
	//
	// We ignore synthetic wrappers, and nested functions. Literal
	// functions passed as arguments to other functions are of
	// course address-taken and there exists a dynamic call of
	// that signature, so when they are unreachable, it is
	// invariably because the parent is unreachable.
	var (
		sourceFuncs    []*ssa.Function
		generated      = make(map[string]bool)
		interfaceTypes = make(map[*types.Package][]*types.Interface)
	)
	packages.Visit(initial, nil, func(p *packages.Package) {
		// Collect interfaces by package for marker method identification.
		var interfaces []*types.Interface
		scope := p.Types.Scope()
		for _, name := range scope.Names() {
			if typeName, ok := scope.Lookup(name).(*types.TypeName); ok &&
				types.IsInterface(typeName.Type()) {
				interfaces = append(interfaces, typeName.Type().Underlying().(*types.Interface))
			}
		}
		interfaceTypes[p.Types] = interfaces

		for _, file := range p.Syntax {
			for _, decl := range file.Decls {
				if decl, ok := decl.(*ast.FuncDecl); ok {
					obj := p.TypesInfo.Defs[decl.Name].(*types.Func)
					fn := prog.FuncValue(obj)
					sourceFuncs = append(sourceFuncs, fn)
				}
			}

			if ast.IsGenerated(file) {
				generated[p.Fset.File(file.Pos()).Name()] = true
			}
		}
	})

	// Compute the reachabilty from main.
	// (Build a call graph only for -whylive.)
	res := rta.Analyze(roots, *whyLiveFlag != "")

	// Subtle: the -test flag causes us to analyze test variants
	// such as "package p as compiled for p.test" or even "for q.test".
	// This leads to multiple distinct ssa.Function instances that
	// represent the same source declaration, and it is essentially
	// impossible to discover this from the SSA representation
	// (since it has lost the connection to go/packages.Package.ID).
	//
	// So, we de-duplicate such variants by position:
	// if any one of them is live, we consider all of them live.
	// (We use Position not Pos to avoid assuming that files common
	// to packages "p" and "p [p.test]" were parsed only once.)
	reachablePosn := make(map[token.Position]bool)
	for fn := range res.Reachable {
		if fn.Pos().IsValid() || fn.Name() == "init" {
			reachablePosn[prog.Fset.Position(fn.Pos())] = true
		}
	}

	// The -whylive=fn flag causes deadcode to explain why a function
	// is not dead, by showing a path to it from some root.
	if *whyLiveFlag != "" {
		targets := make(map[*ssa.Function]bool)
		for _, fn := range sourceFuncs {
			if prettyName(fn, true) == *whyLiveFlag {
				targets[fn] = true
			}
		}
		if len(targets) == 0 {
			// Function is not part of the program.
			//
			// TODO(adonovan): improve the UX here in case
			// of spelling or syntax mistakes. Some ideas:
			// - a cmd/callgraph command to enumerate
			//   available functions.
			// - a deadcode -live flag to compute the complement.
			// - a syntax hint: example.com/pkg.Func or (example.com/pkg.Type).Method
			// - report the element of AllFunctions with the smallest
			//   Levenshtein distance from *whyLiveFlag.
			// - permit -whylive=regexp. But beware of spurious
			//   matches (e.g. fmt.Print matches fmt.Println)
			//   and the annoyance of having to quote parens (*T).f.
			log.Fatalf("function %q not found in program", *whyLiveFlag)
		}

		// Opt: remove the unreachable ones.
		for fn := range targets {
			if !reachablePosn[prog.Fset.Position(fn.Pos())] {
				delete(targets, fn)
			}
		}
		if len(targets) == 0 {
			log.Fatalf("function %s is dead code", *whyLiveFlag)
		}

		res.CallGraph.DeleteSyntheticNodes() // inline synthetic wrappers (except inits)
		root, path := pathSearch(roots, res, targets)
		if root == nil {
			// RTA doesn't add callgraph edges for reflective calls.
			log.Fatalf("%s is reachable only through reflection", *whyLiveFlag)
		}
		if len(path) == 0 {
			// No edges => one of the targets is a root.
			// Rather than (confusingly) print nothing, make this an error.
			log.Fatalf("%s is a root", root.Func)
		}

		// Build a list of jsonEdge records
		// to print as -json or -f=template.
		var edges []any
		for _, edge := range path {
			edges = append(edges, jsonEdge{
				Initial:  cond(len(edges) == 0, prettyName(edge.Caller.Func, true), ""),
				Kind:     cond(isStaticCall(edge), "static", "dynamic"),
				Position: toJSONPosition(prog.Fset.Position(edge.Pos())),
				Callee:   prettyName(edge.Callee.Func, true),
			})
		}
		format := `{{if .Initial}}{{printf "%19s%s\n" "" .Initial}}{{end}}{{printf "%8s@L%.4d --> %s" .Kind .Position.Line .Callee}}`
		if *formatFlag != "" {
			format = *formatFlag
		}
		printObjects(format, edges)
		return
	}

	// Group unreachable functions by package path.
	byPkgPath := make(map[string]map[*ssa.Function]bool)
	for _, fn := range sourceFuncs {
		posn := prog.Fset.Position(fn.Pos())

		if !reachablePosn[posn] {
			reachablePosn[posn] = true // suppress dups with same pos

			pkgpath := fn.Pkg.Pkg.Path()
			m, ok := byPkgPath[pkgpath]
			if !ok {
				m = make(map[*ssa.Function]bool)
				byPkgPath[pkgpath] = m
			}
			m[fn] = true
		}
	}

	// Build array of jsonPackage objects.
	var packages []any
	for _, pkgpath := range slices.Sorted(maps.Keys(byPkgPath)) {
		if !filter.MatchString(pkgpath) {
			continue
		}

		m := byPkgPath[pkgpath]

		// Print functions that appear within the same file in
		// declaration order. This tends to keep related
		// methods such as (T).Marshal and (*T).Unmarshal
		// together better than sorting.
		fns := slices.Collect(maps.Keys(m))
		sort.Slice(fns, func(i, j int) bool {
			xposn := prog.Fset.Position(fns[i].Pos())
			yposn := prog.Fset.Position(fns[j].Pos())
			if xposn.Filename != yposn.Filename {
				return xposn.Filename < yposn.Filename
			}
			return xposn.Line < yposn.Line
		})

		var functions []jsonFunction
		for _, fn := range fns {
			posn := prog.Fset.Position(fn.Pos())

			// Without -generated, skip functions declared in
			// generated Go files.
			// (Functions called by them may still be reported.)
			gen := generated[posn.Filename]
			if gen && !*generatedFlag {
				continue
			}

			// Marker methods should not be reported
			marker := isMarkerMethod(fn, interfaceTypes[fn.Pkg.Pkg])
			if marker {
				continue
			}

			functions = append(functions, jsonFunction{
				Name:      prettyName(fn, false),
				Position:  toJSONPosition(posn),
				Generated: gen,
				Marker:    marker,
			})
		}
		if len(functions) > 0 {
			packages = append(packages, jsonPackage{
				Name:  fns[0].Pkg.Pkg.Name(),
				Path:  pkgpath,
				Funcs: functions,
			})
		}
	}

	// Default line-oriented format: "a/b/c.go:1:2: unreachable func: T.f"
	format := `{{range .Funcs}}{{printf "%s: unreachable func: %s\n" .Position .Name}}{{end}}`
	if *formatFlag != "" {
		format = *formatFlag
	}
	printObjects(format, packages)
}

// prettyName is a fork of Function.String designed to reduce
// go/ssa's fussy punctuation symbols, e.g. "(*pkg.T).F" -> "pkg.T.F".
//
// It only works for functions that remain after
// callgraph.Graph.DeleteSyntheticNodes: source-level named functions
// and methods, their anonymous functions, and synthetic package
// initializers.
func prettyName(fn *ssa.Function, qualified bool) string {
	var buf strings.Builder

	// optional package qualifier
	if qualified && fn.Pkg != nil {
		fmt.Fprintf(&buf, "%s.", fn.Pkg.Pkg.Path())
	}

	var format func(*ssa.Function)
	format = func(fn *ssa.Function) {
		// anonymous?
		if fn.Parent() != nil {
			format(fn.Parent())
			i := slices.Index(fn.Parent().AnonFuncs, fn)
			fmt.Fprintf(&buf, "$%d", i+1)
			return
		}

		// method receiver?
		if recv := fn.Signature.Recv(); recv != nil {
			_, named := typesinternal.ReceiverNamed(recv)
			buf.WriteString(named.Obj().Name())
			buf.WriteByte('.')
		}

		// function/method name
		buf.WriteString(fn.Name())
	}
	format(fn)

	return buf.String()
}

// printObjects formats an array of objects, either as JSON or using a
// template, following the manner of 'go list (-json|-f=template)'.
func printObjects(format string, objects []any) {
	if *jsonFlag {
		out, err := json.MarshalIndent(objects, "", "\t")
		if err != nil {
			log.Fatalf("internal error: %v", err)
		}
		os.Stdout.Write(out)
		return
	}

	// -f=template. Parse can't fail: we checked it earlier.
	tmpl := template.Must(template.New("deadcode").Parse(format))
	for _, object := range objects {
		var buf bytes.Buffer
		if err := tmpl.Execute(&buf, object); err != nil {
			log.Fatal(err)
		}
		if n := buf.Len(); n == 0 || buf.Bytes()[n-1] != '\n' {
			buf.WriteByte('\n')
		}
		os.Stdout.Write(buf.Bytes())
	}
}

// pathSearch returns the shortest path from one of the roots to one
// of the targets (along with the root itself), or zero if no path was found.
func pathSearch(roots []*ssa.Function, res *rta.Result, targets map[*ssa.Function]bool) (*callgraph.Node, []*callgraph.Edge) {
	// Search breadth-first (for shortest path) from the root.
	//
	// We don't use the virtual CallGraph.Root node as we wish to
	// choose the order in which we search entrypoints:
	// non-test packages before test packages,
	// main functions before init functions.

	// Sort roots into preferred order.
	importsTesting := func(fn *ssa.Function) bool {
		isTesting := func(p *types.Package) bool { return p.Path() == "testing" }
		return slices.ContainsFunc(fn.Pkg.Pkg.Imports(), isTesting)
	}
	sort.Slice(roots, func(i, j int) bool {
		x, y := roots[i], roots[j]
		xtest := importsTesting(x)
		ytest := importsTesting(y)
		if xtest != ytest {
			return !xtest // non-tests before tests
		}
		xinit := x.Name() == "init"
		yinit := y.Name() == "init"
		if xinit != yinit {
			return !xinit // mains before inits
		}
		return false
	})

	search := func(allowDynamic bool) (*callgraph.Node, []*callgraph.Edge) {
		// seen maps each encountered node to its predecessor on the
		// path to a root node, or to nil for root itself.
		seen := make(map[*callgraph.Node]*callgraph.Edge)
		bfs := func(root *callgraph.Node) []*callgraph.Edge {
			queue := []*callgraph.Node{root}
			seen[root] = nil
			for len(queue) > 0 {
				node := queue[0]
				queue = queue[1:]

				// found a path?
				if targets[node.Func] {
					path := []*callgraph.Edge{} // non-nil in case len(path)=0
					for {
						edge := seen[node]
						if edge == nil {
							slices.Reverse(path)
							return path
						}
						path = append(path, edge)
						node = edge.Caller
					}
				}

				for _, edge := range node.Out {
					if allowDynamic || isStaticCall(edge) {
						if _, ok := seen[edge.Callee]; !ok {
							seen[edge.Callee] = edge
							queue = append(queue, edge.Callee)
						}
					}
				}
			}
			return nil
		}
		for _, rootFn := range roots {
			root := res.CallGraph.Nodes[rootFn]
			if root == nil {
				// Missing call graph node for root.
				// TODO(adonovan): seems like a bug in rta.
				continue
			}
			if path := bfs(root); path != nil {
				return root, path
			}
		}
		return nil, nil
	}

	for _, allowDynamic := range []bool{false, true} {
		if root, path := search(allowDynamic); path != nil {
			return root, path
		}
	}

	return nil, nil
}

// -- utilities --

func isStaticCall(edge *callgraph.Edge) bool {
	return edge.Site != nil && edge.Site.Common().StaticCallee() != nil
}

var cwd, _ = os.Getwd()

func toJSONPosition(posn token.Position) jsonPosition {
	// Use cwd-relative filename if possible.
	filename := posn.Filename
	if rel, err := filepath.Rel(cwd, filename); err == nil && !strings.HasPrefix(rel, "..") {
		filename = rel
	}

	return jsonPosition{filename, posn.Line, posn.Column}
}

func cond[T any](cond bool, t, f T) T {
	if cond {
		return t
	} else {
		return f
	}
}

// isMarkerMethod reports whether fn is a marker method:
// an unexported, empty-bodied method with no parameters or results
// that implements some named interface type in the same package.
func isMarkerMethod(fn *ssa.Function, interfaceTypes []*types.Interface) bool {
	// Is it an unexported method of no params/results?
	if !(fn.Signature.Recv() != nil &&
		!ast.IsExported(fn.Name()) &&
		fn.Signature.Params() == nil &&
		fn.Signature.Results() == nil) {
		return false
	}

	// Does the method have an empty body?
	body := fn.Syntax().(*ast.FuncDecl).Body
	if body == nil || len(body.List) > 0 {
		return false
	}

	// Does it implement some named interface type in this package?
	return slices.ContainsFunc(interfaceTypes, func(iface *types.Interface) bool {
		return types.Implements(fn.Signature.Recv().Type(), iface)
	})
}

// -- output protocol (for JSON or text/template) --

// Keep in sync with doc comment!

type jsonFunction struct {
	Name      string       // name (sans package qualifier)
	Position  jsonPosition // file/line/column of declaration
	Generated bool         // function is declared in a generated .go file
	Marker    bool         // function is a marker interface method
}

func (f jsonFunction) String() string { return f.Name }

type jsonPackage struct {
	Name  string         // declared name
	Path  string         // full import path
	Funcs []jsonFunction // non-empty list of package's dead functions
}

func (p jsonPackage) String() string { return p.Path }

// The Initial and Callee names are package-qualified.
type jsonEdge struct {
	Initial  string `json:",omitempty"` // initial entrypoint (main or init); first edge only
	Kind     string // = static | dynamic
	Position jsonPosition
	Callee   string
}

type jsonPosition struct {
	File      string
	Line, Col int
}

func (p jsonPosition) String() string {
	return fmt.Sprintf("%s:%d:%d", p.File, p.Line, p.Col)
}


================================================
FILE: cmd/deadcode/deadcode_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main_test

import (
	"bytes"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

// Test runs the deadcode command on each scenario
// described by a testdata/*.txtar file.
func Test(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}

	exe := buildDeadcode(t)

	matches, err := filepath.Glob("testdata/*.txtar")
	if err != nil {
		t.Fatal(err)
	}
	for _, filename := range matches {
		t.Run(filename, func(t *testing.T) {
			t.Parallel()

			ar, err := txtar.ParseFile(filename)
			if err != nil {
				t.Fatal(err)
			}

			// Write the archive files to the temp directory.
			tmpdir := t.TempDir()
			for _, f := range ar.Files {
				filename := filepath.Join(tmpdir, f.Name)
				if err := os.MkdirAll(filepath.Dir(filename), 0777); err != nil {
					t.Fatal(err)
				}
				if err := os.WriteFile(filename, f.Data, 0666); err != nil {
					t.Fatal(err)
				}
			}

			// Parse archive comment as directives of these forms:
			//
			//  [!]deadcode args...	command-line arguments
			//  [!]want arg		expected/unwanted string in output (or stderr)
			//
			// Args may be Go-quoted strings.
			type testcase struct {
				linenum int
				args    []string
				wantErr bool
				want    map[string]bool // string -> sense
			}
			var cases []*testcase
			var current *testcase
			for i, line := range strings.Split(string(ar.Comment), "\n") {
				line = strings.TrimSpace(line)
				if line == "" || line[0] == '#' {
					continue // skip blanks and comments
				}

				words, err := words(line)
				if err != nil {
					t.Fatalf("cannot break line into words: %v (%s)", err, line)
				}
				switch kind := words[0]; kind {
				case "deadcode", "!deadcode":
					current = &testcase{
						linenum: i + 1,
						want:    make(map[string]bool),
						args:    words[1:],
						wantErr: kind[0] == '!',
					}
					cases = append(cases, current)
				case "want", "!want":
					if current == nil {
						t.Fatalf("'want' directive must be after 'deadcode'")
					}
					if len(words) != 2 {
						t.Fatalf("'want' directive needs argument <<%s>>", line)
					}
					current.want[words[1]] = kind[0] != '!'
				default:
					t.Fatalf("%s: invalid directive %q", filename, kind)
				}
			}

			for _, tc := range cases {
				t.Run(fmt.Sprintf("L%d", tc.linenum), func(t *testing.T) {
					// Run the command.
					cmd := exec.Command(exe, tc.args...)
					cmd.Stdout = new(bytes.Buffer)
					cmd.Stderr = new(bytes.Buffer)
					cmd.Dir = tmpdir
					cmd.Env = append(os.Environ(), "GOPROXY=", "GO111MODULE=on")
					var got string
					if err := cmd.Run(); err != nil {
						if !tc.wantErr {
							t.Fatalf("deadcode failed: %v (stderr=%s)", err, cmd.Stderr)
						}
						got = fmt.Sprint(cmd.Stderr)
					} else {
						if tc.wantErr {
							t.Fatalf("deadcode succeeded unexpectedly (stdout=%s)", cmd.Stdout)
						}
						got = fmt.Sprint(cmd.Stdout)
					}

					// Check each want directive.
					for str, sense := range tc.want {
						ok := true
						if strings.Contains(got, str) != sense {
							if sense {
								t.Errorf("missing %q", str)
							} else {
								t.Errorf("unwanted %q", str)
							}
							ok = false
						}
						if !ok {
							t.Errorf("got: <<%s>>", got)
						}
					}
				})
			}
		})
	}
}

// buildDeadcode builds the deadcode executable.
// It returns its path, and a cleanup function.
func buildDeadcode(t *testing.T) string {
	bin := filepath.Join(t.TempDir(), "deadcode")
	if runtime.GOOS == "windows" {
		bin += ".exe"
	}
	cmd := exec.Command("go", "build", "-o", bin)
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("Building deadcode: %v\n%s", err, out)
	}
	return bin
}

// words breaks a string into words, respecting
// Go string quotations around words with spaces.
func words(s string) ([]string, error) {
	var words []string
	for s != "" {
		s = strings.TrimSpace(s)
		var word string
		if s[0] == '"' || s[0] == '`' {
			prefix, err := strconv.QuotedPrefix(s)
			if err != nil {
				return nil, err
			}
			s = s[len(prefix):]
			word, _ = strconv.Unquote(prefix)
		} else {
			prefix, rest, _ := strings.Cut(s, " ")
			s = rest
			word = prefix
		}
		words = append(words, word)
	}
	return words, nil
}


================================================
FILE: cmd/deadcode/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
The deadcode command reports unreachable functions in Go programs.

	Usage: deadcode [flags] package...

The deadcode command loads a Go program from source then uses Rapid
Type Analysis (RTA) to build a call graph of all the functions
reachable from the program's main function. Any functions that are not
reachable are reported as dead code, grouped by package.

Packages are expressed in the notation of 'go list' (or other
underlying build system if you are using an alternative
golang.org/x/go/packages driver). Only executable (main) packages are
considered starting points for the analysis.

The -test flag causes it to analyze test executables too. Tests
sometimes make use of functions that would otherwise appear to be dead
code, and public API functions reported as dead with -test indicate
possible gaps in your test coverage. Bear in mind that an Example test
function without an "Output:" comment is merely documentation:
it is dead code, and does not contribute coverage.

The -filter flag restricts results to packages that match the provided
regular expression; its default value matches the listed packages and any other
packages belonging to the same modules. Use -filter= to display all results.

Example: show all dead code within the gopls module:

	$ deadcode -test golang.org/x/tools/gopls/...

The analysis can soundly analyze dynamic calls though func values,
interface methods, and reflection. However, it does not currently
understand the aliasing created by //go:linkname directives, so it
will fail to recognize that calls to a linkname-annotated function
with no body in fact dispatch to the function named in the annotation.
This may result in the latter function being spuriously reported as dead.

By default, the tool does not report dead functions in generated files,
as determined by the special comment described in
https://go.dev/s/generatedcode. Use the -generated flag to include them.

The tool also does not report marker interface methods by default.
Marker interface methods are typically used to create compile-time constraints
to ensure that only specific types can implement a particular interface.
These methods have no other functionality (empty function body) and are never invoked.
Although marker interface methods are technically unreachable, removing them would break
the interface implementation. Hence, the tool excludes them from the report.

In any case, just because a function is reported as dead does not mean
it is unconditionally safe to delete it. For example, a dead function
may be referenced by another dead function, and a dead method may be
required to satisfy an interface that is never called.
Some judgement is required.

The analysis is valid only for a single GOOS/GOARCH/-tags configuration,
so a function reported as dead may be live in a different configuration.
Consider running the tool once for each configuration of interest.
Consider using a line-oriented output format (see below) to make it
easier to compute the intersection of results across all runs.

# Output

The command supports three output formats.

With no flags, the command prints the name and location of each dead
function in the form of a typical compiler diagnostic, for example:

	$ deadcode -f='{{range .Funcs}}{{println .Position}}{{end}}' -test ./gopls/...
	gopls/internal/protocol/command.go:1206:6: unreachable func: openClientEditor
	gopls/internal/template/parse.go:414:18: unreachable func: Parsed.WriteNode
	gopls/internal/template/parse.go:419:18: unreachable func: wrNode.writeNode

With the -json flag, the command prints an array of Package
objects, as defined by the JSON schema (see below).

With the -f=template flag, the command executes the specified template
on each Package record. So, this template shows dead functions grouped
by package:

	$ deadcode -f='{{println .Path}}{{range .Funcs}}{{printf "\t%s\n" .Name}}{{end}}{{println}}' -test ./gopls/...
	golang.org/x/tools/gopls/internal/lsp
		openClientEditor

	golang.org/x/tools/gopls/internal/template
		Parsed.WriteNode
		wrNode.writeNode

# Why is a function not dead?

The -whylive=function flag explain why the named function is not dead
by showing an arbitrary shortest path to it from one of the main functions.
(To enumerate the functions in a program, or for more sophisticated
call graph queries, use golang.org/x/tools/cmd/callgraph.)

Fully static call paths are preferred over paths involving dynamic
edges, even if longer. Paths starting from a non-test package are
preferred over those from tests. Paths from main functions are
preferred over paths from init functions.

The result is a list of Edge objects (see JSON schema below).
Again, the -json and -f=template flags may be used to control
the formatting of the list of Edge objects.
The default format shows, for each edge in the path, whether the call
is static or dynamic, and its source line number. For example:

	$ deadcode -whylive=bytes.Buffer.String -test ./cmd/deadcode/...
	                 golang.org/x/tools/cmd/deadcode.main
	static@L0117 --> golang.org/x/tools/go/packages.Load
	static@L0262 --> golang.org/x/tools/go/packages.defaultDriver
	static@L0305 --> golang.org/x/tools/go/packages.goListDriver
	static@L0153 --> golang.org/x/tools/go/packages.goListDriver$1
	static@L0154 --> golang.org/x/tools/go/internal/packagesdriver.GetSizesForArgsGolist
	static@L0044 --> bytes.Buffer.String

# JSON schema

	type Package struct {
		Name  string       // declared name
		Path  string       // full import path
		Funcs []Function   // list of dead functions within it
	}

	type Function struct {
		Name      string   // name (sans package qualifier)
		Position  Position // file/line/column of function declaration
		Generated bool     // function is declared in a generated .go file
		Marker    bool     // function is a marker interface method
	}

	type Edge struct {
		Initial  string    // initial entrypoint (main or init); first edge only
		Kind     string    // = static | dynamic
		Position Position  // file/line/column of call site
		Callee   string    // target of the call
	}

	type Position struct {
		File      string   // name of file
		Line, Col int      // line and byte index, both 1-based
	}
*/
package main


================================================
FILE: cmd/deadcode/testdata/basic.txtar
================================================
# Test of basic functionality.

 deadcode -filter= example.com

 want "T.Goodbye"
 want "T.Goodbye2"
 want "T.Goodbye3"
!want "T.Hello"
 want "unreferenced"

 want "Scanf"
 want "Printf"
!want "Println"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

import "fmt"

type T int

func main() {
	var x T
	x.Hello()
}

func (T) Hello() { fmt.Println("hello") }
func (T) Goodbye() { fmt.Println("goodbye") }
func (*T) Goodbye2() { fmt.Println("goodbye2") }
func (*A) Goodbye3() { fmt.Println("goodbye3") }

type A = T

func unreferenced() {}

================================================
FILE: cmd/deadcode/testdata/filterflag.txtar
================================================
# Test of -filter flag.

 deadcode -filter=other.net example.com

 want `other.net`
 want `Dead`
!want `Live`

!want `example.com`
!want `unreferenced`

-- go.work --
use example.com
use other.net

-- example.com/go.mod --
module example.com
go 1.18

-- example.com/main.go --
package main

import "other.net"

func main() {
	other.Live()
}

func unreferenced() {}

-- other.net/go.mod --
module other.net
go 1.18

-- other.net/other.go --
package other

func Live() {}
func Dead() {}


================================================
FILE: cmd/deadcode/testdata/generated.txtar
================================================
# Test of -generated flag output.

 deadcode "-f={{range .Funcs}}{{$.Name}}.{{.Name}}{{end}}" example.com
!want "main.main"
 want "main.Dead1"
!want "main.Dead2"

 deadcode "-f={{range .Funcs}}{{$.Name}}.{{.Name}}{{end}}" -generated example.com
!want "main.main"
 want "main.Dead1"
 want "main.Dead2"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

func main() {}
func Dead1() {}

-- gen.go --
// Code generated by hand. DO NOT EDIT.

package main

func Dead2() {}

================================================
FILE: cmd/deadcode/testdata/issue65915.txtar
================================================
# Regression test for issue 65915: the enumeration of source-level
# functions used the flawed ssautil.AllFunctions, causing it to
# miss some unexported ones.

 deadcode -filter= example.com

 want "unreachable func: example.UnUsed"
 want "unreachable func: example.unUsed"
 want "unreachable func: PublicExample.UnUsed"
 want "unreachable func: PublicExample.unUsed"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

type example struct{}

func (e example) UnUsed() {}

func (e example) Used() {}

func (e example) unUsed() {}

func (e example) used() {}

type PublicExample struct{}

func (p PublicExample) UnUsed() {}

func (p PublicExample) Used() {}

func (p PublicExample) unUsed() {}

func (p PublicExample) used() {}

func main() {
	example{}.Used()
	example{}.used()
	PublicExample{}.Used()
	PublicExample{}.used()
}


================================================
FILE: cmd/deadcode/testdata/issue67915.txt
================================================
# Test of -whylive with reflective call
# (regression test for golang/go#67915).

# The live function is reached via reflection:

 deadcode example.com
 want "unreachable func: dead"
!want "unreachable func: live"

# Reflective calls have Edge.Site=nil, which formerly led to a crash
# when -whylive would compute its position. Now it has NoPos.

 deadcode -whylive=example.com.live example.com
 want "                  example.com.main"
 want " static@L0006 --> reflect.Value.Call"
 want "dynamic@L0000 --> example.com.live"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

import "reflect"

func main() {
	reflect.ValueOf(live).Call(nil)
}

func live() {
	println("hello")
}

func dead() {
	println("goodbye")
}


================================================
FILE: cmd/deadcode/testdata/issue73652.txtar
================================================
# Test deadcode usage under go.work.

 deadcode ./svc/... ./lib/...
 want "unreachable func: A"

# different order of path under the same go.work should behave the same.

 deadcode ./svc/... ./lib/...
 want "unreachable func: A"


-- go.work --
go 1.18

use (
	./lib
	./svc
)

-- lib/go.mod --
module lib.com

go 1.18

-- lib/a/a.go --
package a

func A() {}

-- svc/go.mod --
module svc.com

go 1.18

-- svc/s/main.go --
package main

func main() { println("main") }



================================================
FILE: cmd/deadcode/testdata/jsonflag.txtar
================================================
# Very minimal test of -json flag.

deadcode -json example.com/p

 want `"Path": "example.com/p",`
 want `"Name": "DeadFunc",`
 want `"Generated": false`
 want `"Line": 5,`
 want `"Col": 6`

-- go.mod --
module example.com
go 1.18

-- p/p.go --
package main

func main() {}

func DeadFunc() {}

type T int
func (*T) DeadMethod() {}

================================================
FILE: cmd/deadcode/testdata/lineflag.txtar
================================================
# Test of line-oriented output.

 deadcode `-f={{range .Funcs}}{{printf "%s: %s.%s\n" .Position $.Path .Name}}{{end}}` -filter= example.com

 want "main.go:13:10: example.com.T.Goodbye"
!want "example.com.T.Hello"
 want "main.go:15:6: example.com.unreferenced"

 want "fmt.Scanf"
 want "fmt.Printf"
!want "fmt.Println"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

import "fmt"

type T int

func main() {
	var x T
	x.Hello()
}

func (T) Hello() { fmt.Println("hello") }
func (T) Goodbye() { fmt.Println("goodbye") }

func unreferenced() {}

================================================
FILE: cmd/deadcode/testdata/marker.txtar
================================================
# Test of marker suppression functionality.
# Deadcode should not identify marker interface methods as unreachable

 deadcode -filter= example.com
!want "T.isMarker"
want "R.isNotMarker"
!want "P.greet"
want "Q.greet"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main
import "fmt"

// Marker method: implements interface, unexported, no params, no results, empty body
type Marker interface {
    isMarker()
}
type T struct{}

func (t *T) isMarker() {}

// Not marker method: does not implement interface
type R struct {}
func (r *R) isNotMarker() {}

// Ensure that it still reports valid interface methods
// when unused
type Greeter interface {
    greet()
}
type P struct {}
func (p *P) greet() {fmt.Println("P: hello")}
type Q struct {}
func (q *Q) greet() {fmt.Println("Q: hello")} // this method should be reported

func main () {
    var p P
    p.greet()
}

================================================
FILE: cmd/deadcode/testdata/testflag.txtar
================================================
# Test of -test flag.

deadcode -test -filter=example.com example.com/p

 want "Dead"
!want "Live1"
!want "Live2"

 want "ExampleDead"
!want "ExampleLive"

-- go.mod --
module example.com
go 1.18

-- p/p.go --
package p

func Live1() {}
func Live2() {}
func Dead() {}

-- p/p_test.go --
package p_test

import "example.com/p"

import "testing"

func Test(t *testing.T) {
	p.Live1()
}

func ExampleLive() {
	p.Live2()
	// Output:
}

// A test Example function without an "Output:" comment is never executed.
func ExampleDead() {
	p.Dead()
}

================================================
FILE: cmd/deadcode/testdata/whylive.txtar
================================================
# Test of -whylive flag.

# The -whylive argument must be live.

!deadcode -whylive=example.com.d example.com
 want "function example.com.d is dead code"

# A fully static path is preferred, even if longer.

 deadcode -whylive=example.com.c example.com
 want "                  example.com.main"
 want " static@L0004 --> example.com.a"
 want " static@L0009 --> example.com.b"
 want " static@L0012 --> example.com.c"

# Dynamic edges are followed if necessary.
# (Note that main is preferred over init.)

 deadcode -whylive=example.com.f example.com
 want "                  example.com.main"
 want "dynamic@L0006 --> example.com.e"
 want " static@L0017 --> example.com.f"

# Degenerate case where target is itself a root.

!deadcode -whylive=example.com.main example.com
 want "example.com.main is a root"

# Test of path through (*T).m method wrapper.

 deadcode -whylive=example.com/p.live example.com/p
 want "                 example.com/p.main"
 want "static@L0006 --> example.com/p.E.Error"
 want "static@L0010 --> example.com/p.live"

# Test of path through (I).m interface method wrapper (thunk).

 deadcode -whylive=example.com/q.live example.com/q
 want "                 example.com/q.main"
 want "static@L0006 --> example.com/q.E.Error"
 want "static@L0010 --> example.com/q.live"

# Test of path through synthetic package initializer,
# a declared package initializer, and its anonymous function.

 deadcode -whylive=example.com/q.live2 example.com/q
 want "                 example.com/q.init"
 want "static@L0000 --> example.com/q.init#1"
 want "static@L0016 --> example.com/q.init#1$1"
 want "static@L0015 --> example.com/q.live2"

# Test of path through synthetic package initializer,
# and a global var initializer.

 deadcode -whylive=example.com/r.live example.com/r
 want "                 example.com/r.init"
 want "static@L0007 --> example.com/r.init$1"
 want "static@L0006 --> example.com/r.live"

-- go.mod --
module example.com
go 1.18

-- main.go --
package main

func main() {
	a()
	println(c, e) // c, e are address-taken
	(func ())(nil)() // potential dynamic call to c, e
}
func a() {
	b()
}
func b() {
	c()
}
func c()
func d()
func e() {
	f()
}
func f()

func init() {
     (func ())(nil)() // potential dynamic call to c, e
}

-- p/p.go --
package main

func main() {
	f := (*E).Error
	var e E
	f(&e)
}

type E int
func (E) Error() string { return live() }

func live() string

-- q/q.go --
package main

func main() {
	f := error.Error
	var e E
	f(e)
}

type E int
func (E) Error() string { return live() }

func live() string

func init() {
	f := func() { live2() }
	f()
}

func live2()

-- r/r.go --
package main

func main() {}

var x = func() int {
	return live()
}()

func live() int


================================================
FILE: cmd/digraph/digraph.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main // import "golang.org/x/tools/cmd/digraph"

// TODO(adonovan):
// - support input files other than stdin
// - support alternative formats (AT&T GraphViz, CSV, etc),
//   a comment syntax, etc.
// - allow queries to nest, like Blaze query language.

import (
	"bufio"
	"bytes"
	_ "embed"
	"errors"
	"flag"
	"fmt"
	"io"
	"os"
	"sort"
	"strconv"
	"strings"
	"unicode"
	"unicode/utf8"
)

func usage() {
	// Extract the content of the /* ... */ comment in doc.go.
	_, after, _ := strings.Cut(doc, "/*")
	doc, _, _ := strings.Cut(after, "*/")
	io.WriteString(flag.CommandLine.Output(), doc)
	flag.PrintDefaults()

	os.Exit(2)
}

//go:embed doc.go
var doc string

func main() {
	flag.Usage = usage
	flag.Parse()

	args := flag.Args()
	if len(args) == 0 {
		usage()
	}

	if err := digraph(args[0], args[1:]); err != nil {
		fmt.Fprintf(os.Stderr, "digraph: %s\n", err)
		os.Exit(1)
	}
}

type nodelist []string

func (l nodelist) println(sep string) {
	for i, node := range l {
		if i > 0 {
			fmt.Fprint(stdout, sep)
		}
		fmt.Fprint(stdout, node)
	}
	fmt.Fprintln(stdout)
}

type nodeset map[string]bool

func singleton(x string) nodeset { return nodeset{x: true} }

func (s nodeset) sort() nodelist {
	nodes := make(nodelist, len(s))
	var i int
	for node := range s {
		nodes[i] = node
		i++
	}
	sort.Strings(nodes)
	return nodes
}

func (s nodeset) addAll(x nodeset) {
	for node := range x {
		s[node] = true
	}
}

// A graph maps nodes to the non-nil set of their immediate successors.
type graph map[string]nodeset

func (g graph) addNode(node string) nodeset {
	edges := g[node]
	if edges == nil {
		edges = make(nodeset)
		g[node] = edges
	}
	return edges
}

func (g graph) addEdges(from string, to ...string) {
	edges := g.addNode(from)
	for _, to := range to {
		g.addNode(to)
		edges[to] = true
	}
}

func (g graph) nodelist() nodelist {
	nodes := make(nodeset)
	for node := range g {
		nodes[node] = true
	}
	return nodes.sort()
}

func (g graph) reachableFrom(roots nodeset) nodeset {
	seen := make(nodeset)
	var visit func(node string)
	visit = func(node string) {
		if !seen[node] {
			seen[node] = true
			for e := range g[node] {
				visit(e)
			}
		}
	}
	for root := range roots {
		visit(root)
	}
	return seen
}

func (g graph) transpose() graph {
	rev := make(graph)
	for node, edges := range g {
		rev.addNode(node)
		for succ := range edges {
			rev.addEdges(succ, node)
		}
	}
	return rev
}

func (g graph) sccs() []nodeset {
	// Kosaraju's algorithm---Tarjan is overkill here.

	// Forward pass.
	S := make(nodelist, 0, len(g)) // postorder stack
	seen := make(nodeset)
	var visit func(node string)
	visit = func(node string) {
		if !seen[node] {
			seen[node] = true
			for e := range g[node] {
				visit(e)
			}
			S = append(S, node)
		}
	}
	for node := range g {
		visit(node)
	}

	// Reverse pass.
	rev := g.transpose()
	var scc nodeset
	seen = make(nodeset)
	var rvisit func(node string)
	rvisit = func(node string) {
		if !seen[node] {
			seen[node] = true
			scc[node] = true
			for e := range rev[node] {
				rvisit(e)
			}
		}
	}
	var sccs []nodeset
	for len(S) > 0 {
		top := S[len(S)-1]
		S = S[:len(S)-1] // pop
		if !seen[top] {
			scc = make(nodeset)
			rvisit(top)
			if len(scc) == 1 && !g[top][top] {
				continue
			}
			sccs = append(sccs, scc)
		}
	}
	return sccs
}

func (g graph) allpaths(from, to string) error {
	// We intersect the forward closure of 'from' with
	// the reverse closure of 'to'. This is not the most
	// efficient implementation, but it's the clearest,
	// and the previous one had bugs.
	seen := g.reachableFrom(singleton(from))
	rev := g.transpose().reachableFrom(singleton(to))
	for n := range seen {
		if !rev[n] {
			delete(seen, n)
		}
	}

	// For each marked node, collect its marked successors.
	var edges []string
	for n := range seen {
		for succ := range g[n] {
			if seen[succ] {
				edges = append(edges, n+" "+succ)
			}
		}
	}

	// Sort (so that this method is deterministic) and print edges.
	sort.Strings(edges)
	for _, e := range edges {
		fmt.Fprintln(stdout, e)
	}

	return nil
}

func (g graph) somepath(from, to string) error {
	// Search breadth-first so that we return a minimal path.

	// A path is a linked list whose head is a candidate "to" node
	// and whose tail is the path ending in the "from" node.
	type path struct {
		node string
		tail *path
	}

	seen := singleton(from)

	var queue []*path
	queue = append(queue, &path{node: from, tail: nil})
	for len(queue) > 0 {
		p := queue[0]
		queue = queue[1:]

		if p.node == to {
			// Found a path. Print, tail first.
			var print func(p *path)
			print = func(p *path) {
				if p.tail != nil {
					print(p.tail)
					fmt.Fprintln(stdout, p.tail.node+" "+p.node)
				}
			}
			print(p)
			return nil
		}

		for succ := range g[p.node] {
			if !seen[succ] {
				seen[succ] = true
				queue = append(queue, &path{node: succ, tail: p})
			}
		}
	}
	return fmt.Errorf("no path from %q to %q", from, to)
}

func (g graph) toDot(w *bytes.Buffer) {
	fmt.Fprintln(w, "digraph {")
	for _, src := range g.nodelist() {
		for _, dst := range g[src].sort() {
			// Dot's quoting rules appear to align with Go's for escString,
			// which is the syntax of node IDs. Labels require significantly
			// more quoting, but that appears not to be necessary if the node ID
			// is implicitly used as the label.
			fmt.Fprintf(w, "\t%q -> %q;\n", src, dst)
		}
	}
	fmt.Fprintln(w, "}")
}

func parse(rd io.Reader) (graph, error) {
	g := make(graph)

	var linenum int
	// We avoid bufio.Scanner as it imposes a (configurable) limit
	// on line length, whereas Reader.ReadString does not.
	in := bufio.NewReader(rd)
	for {
		linenum++
		line, err := in.ReadString('\n')
		eof := false
		if err == io.EOF {
			eof = true
		} else if err != nil {
			return nil, err
		}
		// Split into words, honoring double-quotes per Go spec.
		words, err := split(line)
		if err != nil {
			return nil, fmt.Errorf("at line %d: %v", linenum, err)
		}
		if len(words) > 0 {
			g.addEdges(words[0], words[1:]...)
		}
		if eof {
			break
		}
	}
	return g, nil
}

// Overridable for redirection.
var stdin io.Reader = os.Stdin
var stdout io.Writer = os.Stdout

func digraph(cmd string, args []string) error {
	// Parse the input graph.
	g, err := parse(stdin)
	if err != nil {
		return err
	}

	// Parse the command line.
	switch cmd {
	case "nodes":
		if len(args) != 0 {
			return fmt.Errorf("usage: digraph nodes")
		}
		g.nodelist().println("\n")

	case "degree":
		if len(args) != 0 {
			return fmt.Errorf("usage: digraph degree")
		}
		nodes := make(nodeset)
		for node := range g {
			nodes[node] = true
		}
		rev := g.transpose()
		for _, node := range nodes.sort() {
			fmt.Fprintf(stdout, "%d\t%d\t%s\n", len(rev[node]), len(g[node]), node)
		}

	case "transpose":
		if len(args) != 0 {
			return fmt.Errorf("usage: digraph transpose")
		}
		var revEdges []string
		for node, succs := range g.transpose() {
			for succ := range succs {
				revEdges = append(revEdges, fmt.Sprintf("%s %s", node, succ))
			}
		}
		sort.Strings(revEdges) // make output deterministic
		for _, e := range revEdges {
			fmt.Fprintln(stdout, e)
		}

	case "succs", "preds":
		if len(args) == 0 {
			return fmt.Errorf("usage: digraph %s <node> ... ", cmd)
		}
		g := g
		if cmd == "preds" {
			g = g.transpose()
		}
		result := make(nodeset)
		for _, root := range args {
			edges := g[root]
			if edges == nil {
				return fmt.Errorf("no such node %q", root)
			}
			result.addAll(edges)
		}
		result.sort().println("\n")

	case "forward", "reverse":
		if len(args) == 0 {
			return fmt.Errorf("usage: digraph %s <node> ... ", cmd)
		}
		roots := make(nodeset)
		for _, root := range args {
			if g[root] == nil {
				return fmt.Errorf("no such node %q", root)
			}
			roots[root] = true
		}
		g := g
		if cmd == "reverse" {
			g = g.transpose()
		}
		g.reachableFrom(roots).sort().println("\n")

	case "somepath":
		if len(args) != 2 {
			return fmt.Errorf("usage: digraph somepath <from> <to>")
		}
		from, to := args[0], args[1]
		if g[from] == nil {
			return fmt.Errorf("no such 'from' node %q", from)
		}
		if g[to] == nil {
			return fmt.Errorf("no such 'to' node %q", to)
		}
		if err := g.somepath(from, to); err != nil {
			return err
		}

	case "allpaths":
		if len(args) != 2 {
			return fmt.Errorf("usage: digraph allpaths <from> <to>")
		}
		from, to := args[0], args[1]
		if g[from] == nil {
			return fmt.Errorf("no such 'from' node %q", from)
		}
		if g[to] == nil {
			return fmt.Errorf("no such 'to' node %q", to)
		}
		if err := g.allpaths(from, to); err != nil {
			return err
		}

	case "sccs":
		if len(args) != 0 {
			return fmt.Errorf("usage: digraph sccs")
		}
		buf := new(bytes.Buffer)
		oldStdout := stdout
		stdout = buf
		for _, scc := range g.sccs() {
			scc.sort().println(" ")
		}
		lines := strings.SplitAfter(buf.String(), "\n")
		sort.Strings(lines)
		stdout = oldStdout
		io.WriteString(stdout, strings.Join(lines, ""))

	case "scc":
		if len(args) != 1 {
			return fmt.Errorf("usage: digraph scc <node>")
		}
		node := args[0]
		if g[node] == nil {
			return fmt.Errorf("no such node %q", node)
		}
		for _, scc := range g.sccs() {
			if scc[node] {
				scc.sort().println("\n")
				break
			}
		}

	case "focus":
		if len(args) != 1 {
			return fmt.Errorf("usage: digraph focus <node>")
		}
		node := args[0]
		if g[node] == nil {
			return fmt.Errorf("no such node %q", node)
		}

		edges := make(map[string]struct{})
		for from := range g.reachableFrom(singleton(node)) {
			for to := range g[from] {
				edges[fmt.Sprintf("%s %s", from, to)] = struct{}{}
			}
		}

		gtrans := g.transpose()
		for from := range gtrans.reachableFrom(singleton(node)) {
			for to := range gtrans[from] {
				edges[fmt.Sprintf("%s %s", to, from)] = struct{}{}
			}
		}

		edgesSorted := make([]string, 0, len(edges))
		for e := range edges {
			edgesSorted = append(edgesSorted, e)
		}
		sort.Strings(edgesSorted)
		fmt.Fprintln(stdout, strings.Join(edgesSorted, "\n"))

	case "to":
		if len(args) != 1 || args[0] != "dot" {
			return fmt.Errorf("usage: digraph to dot")
		}
		var b bytes.Buffer
		g.toDot(&b)
		stdout.Write(b.Bytes())

	default:
		return fmt.Errorf("no such command %q", cmd)
	}

	return nil
}

// -- Utilities --------------------------------------------------------

// split splits a line into words, which are generally separated by
// spaces, but Go-style double-quoted string literals are also supported.
// (This approximates the behaviour of the Bourne shell.)
//
//	`one "two three"` -> ["one" "two three"]
//	`a"\n"b` -> ["a\nb"]
func split(line string) ([]string, error) {
	var (
		words   []string
		inWord  bool
		current bytes.Buffer
	)

	for len(line) > 0 {
		r, size := utf8.DecodeRuneInString(line)
		if unicode.IsSpace(r) {
			if inWord {
				words = append(words, current.String())
				current.Reset()
				inWord = false
			}
		} else if r == '"' {
			var ok bool
			size, ok = quotedLength(line)
			if !ok {
				return nil, errors.New("invalid quotation")
			}
			s, err := strconv.Unquote(line[:size])
			if err != nil {
				return nil, err
			}
			current.WriteString(s)
			inWord = true
		} else {
			current.WriteRune(r)
			inWord = true
		}
		line = line[size:]
	}
	if inWord {
		words = append(words, current.String())
	}
	return words, nil
}

// quotedLength returns the length in bytes of the prefix of input that
// contain a possibly-valid double-quoted Go string literal.
//
// On success, n is at least two (""); input[:n] may be passed to
// strconv.Unquote to interpret its value, and input[n:] contains the
// rest of the input.
//
// On failure, quotedLength returns false, and the entire input can be
// passed to strconv.Unquote if an informative error message is desired.
//
// quotedLength does not and need not detect all errors, such as
// invalid hex or octal escape sequences, since it assumes
// strconv.Unquote will be applied to the prefix.  It guarantees only
// that if there is a prefix of input containing a valid string literal,
// its length is returned.
//
// TODO(adonovan): move this into a strconv-like utility package.
func quotedLength(input string) (n int, ok bool) {
	var offset int

	// next returns the rune at offset, or -1 on EOF.
	// offset advances to just after that rune.
	next := func() rune {
		if offset < len(input) {
			r, size := utf8.DecodeRuneInString(input[offset:])
			offset += size
			return r
		}
		return -1
	}

	if next() != '"' {
		return // error: not a quotation
	}

	for {
		r := next()
		if r == '\n' || r < 0 {
			return // error: string literal not terminated
		}
		if r == '"' {
			return offset, true // success
		}
		if r == '\\' {
			var skip int
			switch next() {
			case 'a', 'b', 'f', 'n', 'r', 't', 'v', '\\', '"':
				skip = 0
			case '0', '1', '2', '3', '4', '5', '6', '7':
				skip = 2
			case 'x':
				skip = 2
			case 'u':
				skip = 4
			case 'U':
				skip = 8
			default:
				return // error: invalid escape
			}

			for i := 0; i < skip; i++ {
				next()
			}
		}
	}
}


================================================
FILE: cmd/digraph/digraph_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main

import (
	"bytes"
	"fmt"
	"io"
	"reflect"
	"sort"
	"strings"
	"testing"
)

func TestDigraph(t *testing.T) {
	const g1 = `
socks shoes
shorts pants
pants belt shoes
shirt tie sweater
sweater jacket
hat
`

	const g2 = `
a b c
b d
c d
d c
e e
`

	for _, test := range []struct {
		name  string
		input string
		cmd   string
		args  []string
		want  string
	}{
		{"nodes", g1, "nodes", nil, "belt\nhat\njacket\npants\nshirt\nshoes\nshorts\nsocks\nsweater\ntie\n"},
		{"reverse", g1, "reverse", []string{"jacket"}, "jacket\nshirt\nsweater\n"},
		{"transpose", g1, "transpose", nil, "belt pants\njacket sweater\npants shorts\nshoes pants\nshoes socks\nsweater shirt\ntie shirt\n"},
		{"forward", g1, "forward", []string{"socks"}, "shoes\nsocks\n"},
		{"forward multiple args", g1, "forward", []string{"socks", "sweater"}, "jacket\nshoes\nsocks\nsweater\n"},
		{"scss", g2, "sccs", nil, "c d\ne\n"},
		{"scc", g2, "scc", []string{"d"}, "c\nd\n"},
		{"succs", g2, "succs", []string{"a"}, "b\nc\n"},
		{"succs-long-token", g2 + "x " + strings.Repeat("x", 96*1024), "succs", []string{"x"}, strings.Repeat("x", 96*1024) + "\n"},
		{"preds", g2, "preds", []string{"c"}, "a\nd\n"},
		{"preds multiple args", g2, "preds", []string{"c", "d"}, "a\nb\nc\nd\n"},
	} {
		t.Run(test.name, func(t *testing.T) {
			stdin = strings.NewReader(test.input)
			stdout = new(bytes.Buffer)
			if err := digraph(test.cmd, test.args); err != nil {
				t.Fatal(err)
			}

			got := stdout.(fmt.Stringer).String()
			if got != test.want {
				t.Errorf("digraph(%s, %s) = got %q, want %q", test.cmd, test.args, got, test.want)
			}
		})
	}

	// TODO(adonovan):
	// - test errors
}

func TestAllpaths(t *testing.T) {
	for _, test := range []struct {
		name string
		in   string
		to   string // from is always "A"
		want string
	}{
		{
			name: "Basic",
			in:   "A B\nB C",
			to:   "B",
			want: "A B\n",
		},
		{
			name: "Long",
			in:   "A B\nB C\n",
			to:   "C",
			want: "A B\nB C\n",
		},
		{
			name: "Cycle Basic",
			in:   "A B\nB A",
			to:   "B",
			want: "A B\nB A\n",
		},
		{
			name: "Cycle Path Out",
			// A <-> B -> C -> D
			in:   "A B\nB A\nB C\nC D",
			to:   "C",
			want: "A B\nB A\nB C\n",
		},
		{
			name: "Cycle Path Out Further Out",
			// A -> B <-> C -> D -> E
			in:   "A B\nB C\nC D\nC B\nD E",
			to:   "D",
			want: "A B\nB C\nC B\nC D\n",
		},
		{
			name: "Two Paths Basic",
			//           /-> C --\
			// A -> B --          -> E -> F
			//           \-> D --/
			in:   "A B\nB C\nC E\nB D\nD E\nE F",
			to:   "E",
			want: "A B\nB C\nB D\nC E\nD E\n",
		},
		{
			name: "Two Paths With One Immediately From Start",
			//      /-> B -+ -> D
			// A --        |
			//      \-> C <+
			in:   "A B\nA C\nB C\nB D",
			to:   "C",
			want: "A B\nA C\nB C\n",
		},
		{
			name: "Two Paths Further Up",
			//      /-> B --\
			// A --          -> D -> E -> F
			//      \-> C --/
			in:   "A B\nA C\nB D\nC D\nD E\nE F",
			to:   "E",
			want: "A B\nA C\nB D\nC D\nD E\n",
		},
		{
			// We should include A - C  - D even though it's further up the
			// second path than D (which would already be in the graph by
			// the time we get around to integrating the second path).
			name: "Two Splits",
			//      /-> B --\         /-> E --\
			// A --           -> D --          -> G -> H
			//      \-> C --/         \-> F --/
			in:   "A B\nA C\nB D\nC D\nD E\nD F\nE G\nF G\nG H",
			to:   "G",
			want: "A B\nA C\nB D\nC D\nD E\nD F\nE G\nF G\n",
		},
		{
			// D - E should not be duplicated.
			name: "Two Paths - Two Splits With Gap",
			//      /-> B --\              /-> F --\
			// A --           -> D -> E --          -> H -> I
			//      \-> C --/              \-> G --/
			in:   "A B\nA C\nB D\nC D\nD E\nE F\nE G\nF H\nG H\nH I",
			to:   "H",
			want: "A B\nA C\nB D\nC D\nD E\nE F\nE G\nF H\nG H\n",
		},
		{
			// C <--> B --> A --> D <--> E
			//        ⋃
			name: "non-regression test for #74842",
			in:   "A D\nB A\nB B\nB C\nC B\nD E\nE D",
			to:   "D",
			want: "A D\nD E\nE D\n",
		},
		{
			// A --> B --> D
			//       ^
			//       v
			//       C[123]
			name: "regression test for #74842",
			in:   "A B\nB C1\nB C2\nB C3\nB D\nC1 B\nC2 B\nC3 B\n",
			to:   "D",
			want: "A B\nB C1\nB C2\nB C3\nB D\nC1 B\nC2 B\nC3 B\n",
		},
		{
			// A -------> B --> D
			//  \--> C ---^     |
			//       ^----------+
			name: "another regression test for #74842",
			in:   "A B\nA C\nB D\nC B\nD C\n",
			to:   "D",
			want: "A B\nA C\nB D\nC B\nD C\n",
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			stdin = strings.NewReader(test.in)
			stdout = new(bytes.Buffer)
			if err := digraph("allpaths", []string{"A", test.to}); err != nil {
				t.Fatal(err)
			}

			got := stdout.(fmt.Stringer).String()
			if got != test.want {
				t.Errorf("digraph(allpaths, A, %s) = got %q, want %q", test.to, got, test.want)
			}
		})
	}
}

func TestSomepath(t *testing.T) {
	for _, test := range []struct {
		name string
		in   string
		to   string
		// somepath is non-deterministic, so we have to provide all the
		// possible options. Each option is separated with |.
		wantAnyOf string
	}{
		{
			name:      "Basic",
			in:        "A B\n",
			to:        "B",
			wantAnyOf: "A B",
		},
		{
			name:      "Basic With Cycle",
			in:        "A B\nB A",
			to:        "B",
			wantAnyOf: "A B",
		},
		{
			name: "Two Paths",
			//      /-> B --\
			// A --          -> D
			//      \-> C --/
			in:        "A B\nA C\nB D\nC D",
			to:        "D",
			wantAnyOf: "A B\nB D|A C\nC D",
		},
		{
			name: "Printed path is minimal",
			// A -> B1->B2->B3 -> E
			// A -> C1->C2 -> E
			// A -> D -> E
			in:        "A D C1 B1\nD E\nC1 C2\nC2 E\nB1 B2\nB2 B3\nB3 E",
			to:        "E",
			wantAnyOf: "A D\nD E",
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			stdin = strings.NewReader(test.in)
			stdout = new(bytes.Buffer)
			if err := digraph("somepath", []string{"A", test.to}); err != nil {
				t.Fatal(err)
			}

			got := stdout.(fmt.Stringer).String()
			lines := strings.Split(got, "\n")
			sort.Strings(lines)
			got = strings.Join(lines[1:], "\n")

			var oneMatch bool
			for want := range strings.SplitSeq(test.wantAnyOf, "|") {
				if got == want {
					oneMatch = true
				}
			}
			if !oneMatch {
				t.Errorf("digraph(somepath, A, %s) = got %q, want any of\n%s", test.to, got, test.wantAnyOf)
			}
		})
	}
}

func TestSplit(t *testing.T) {
	for _, test := range []struct {
		line string
		want []string
	}{
		{`one "2a 2b" three`, []string{"one", "2a 2b", "three"}},
		{`one tw"\n\x0a\u000a\012"o three`, []string{"one", "tw\n\n\n\no", "three"}},
	} {
		got, err := split(test.line)
		if err != nil {
			t.Errorf("split(%s) failed: %v", test.line, err)
		}
		if !reflect.DeepEqual(got, test.want) {
			t.Errorf("split(%s) = %v, want %v", test.line, got, test.want)
		}
	}
}

func TestQuotedLength(t *testing.T) {
	for _, test := range []struct {
		input string
		want  int
	}{
		{`"abc"`, 5},
		{`"abc"def`, 5},
		{`"abc\"d"ef`, 8}, // "abc\"d" is consumed, ef is residue
		{`"\012\n\x0a\u000a\U0000000a"`, 28},
		{"\"\xff\"", 3}, // bad UTF-8 is ok
		{`"\xff"`, 6},   // hex escape for bad UTF-8 is ok
	} {
		got, ok := quotedLength(test.input)
		if !ok {
			got = 0
		}
		if got != test.want {
			t.Errorf("quotedLength(%s) = %d, want %d", test.input, got, test.want)
		}
	}

	// errors
	for _, input := range []string{
		``,            // not a quotation
		`a`,           // not a quotation
		`'a'`,         // not a quotation
		`"a`,          // not terminated
		`"\0"`,        // short octal escape
		`"\x1"`,       // short hex escape
		`"\u000"`,     // short \u escape
		`"\U0000000"`, // short \U escape
		`"\k"`,        // invalid escape
		"\"ab\nc\"",   // newline
	} {
		if n, ok := quotedLength(input); ok {
			t.Errorf("quotedLength(%s) = %d, want !ok", input, n)
		}
	}
}

func TestFocus(t *testing.T) {
	for _, test := range []struct {
		name  string
		in    string
		focus string
		want  string
	}{
		{
			name:  "Basic",
			in:    "A B",
			focus: "B",
			want:  "A B\n",
		},
		{
			name: "Some Nodes Not Included",
			// C does not have a path involving B, and should not be included
			// in the output.
			in:    "A B\nA C",
			focus: "B",
			want:  "A B\n",
		},
		{
			name: "Cycle In Path",
			// A <-> B -> C
			in:    "A B\nB A\nB C",
			focus: "C",
			want:  "A B\nB A\nB C\n",
		},
		{
			name: "Cycle Out Of Path",
			// C <- A <->B
			in:    "A B\nB A\nB C",
			focus: "C",
			want:  "A B\nB A\nB C\n",
		},
		{
			name: "Complex",
			// Paths in and out from focus.
			//                   /-> F
			//      /-> B -> D --
			// A --              \-> E
			//      \-> C
			in:    "A B\nA C\nB D\nD F\nD E",
			focus: "D",
			want:  "A B\nB D\nD E\nD F\n",
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			stdin = strings.NewReader(test.in)
			stdout = new(bytes.Buffer)
			if err := digraph("focus", []string{test.focus}); err != nil {
				t.Fatal(err)
			}
			got := stdout.(fmt.Stringer).String()
			if got != test.want {
				t.Errorf("digraph(focus, %s) = got %q, want %q", test.focus, got, test.want)
			}
		})
	}
}

func TestToDot(t *testing.T) {
	in := `a b c
b "d\"\\d"
c "d\"\\d"`
	want := `digraph {
	"a" -> "b";
	"a" -> "c";
	"b" -> "d\"\\d";
	"c" -> "d\"\\d";
}
`
	defer func(in io.Reader, out io.Writer) { stdin, stdout = in, out }(stdin, stdout)
	stdin = strings.NewReader(in)
	stdout = new(bytes.Buffer)
	if err := digraph("to", []string{"dot"}); err != nil {
		t.Fatal(err)
	}
	got := stdout.(fmt.Stringer).String()
	if got != want {
		t.Errorf("digraph(to, dot) = got %q, want %q", got, want)
	}

}


================================================
FILE: cmd/digraph/doc.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
The digraph command performs queries over unlabelled directed graphs
represented in text form.  It is intended to integrate nicely with
typical UNIX command pipelines.

Usage:

	your-application | digraph [command]

The supported commands are:

	nodes
		the set of all nodes
	degree
		the in-degree and out-degree of each node
	transpose
		the reverse of the input edges
	preds <node> ...
		the set of immediate predecessors of the specified nodes
	succs <node> ...
		the set of immediate successors of the specified nodes
	forward <node> ...
		the set of nodes transitively reachable from the specified nodes
	reverse <node> ...
		the set of nodes that transitively reach the specified nodes
	somepath <node> <node>
		the list of edges on some arbitrary path from the first node to the second
	allpaths <node> <node>
		the set of edges on all paths from the first node to the second
	sccs
		all strongly connected components (one per line)
	scc <node>
		the set of nodes strongly connected to the specified one
	focus <node>
		the subgraph containing all directed paths that pass through the specified node
	to dot
		print the graph in Graphviz dot format (other formats may be supported in the future)

Input format:

Each line contains zero or more words. Words are separated by unquoted
whitespace; words may contain Go-style double-quoted portions, allowing spaces
and other characters to be expressed.

Each word declares a node, and if there are more than one, an edge from the
first to each subsequent one. The graph is provided on the standard input.

For instance, the following (acyclic) graph specifies a partial order among the
subtasks of getting dressed:

	$ cat clothes.txt
	socks shoes
	"boxer shorts" pants
	pants belt shoes
	shirt tie sweater
	sweater jacket
	hat

The line "shirt tie sweater" indicates the two edges shirt -> tie and
shirt -> sweater, not shirt -> tie -> sweater.

Example usage:

Show which clothes (see above) must be donned before a jacket:

	$ digraph reverse jacket

Many tools can be persuaded to produce output in digraph format,
as in the following examples.

Using an import graph produced by go list, show a path that indicates
why the gopls application depends on the cmp package:

	$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/gopls |
		digraph somepath golang.org/x/tools/gopls github.com/google/go-cmp/cmp

Show which packages in x/tools depend, perhaps indirectly, on the callgraph package:

	$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps golang.org/x/tools/... |
		digraph reverse golang.org/x/tools/go/callgraph

Visualize the package dependency graph of the current package:

	$ go list -f '{{.ImportPath}} {{join .Imports " "}}' -deps |
		digraph to dot | dot -Tpng -o x.png

Using a module graph produced by go mod, show all dependencies of the current module:

	$ go mod graph | digraph forward $(go list -m)
*/
package main


================================================
FILE: cmd/eg/eg.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The eg command performs example-based refactoring.
// For documentation, run the command, or see Help in
// golang.org/x/tools/refactor/eg.
package main // import "golang.org/x/tools/cmd/eg"

import (
	"flag"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"os/exec"
	"path/filepath"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/refactor/eg"
)

var (
	beforeeditFlag = flag.String("beforeedit", "", "A command to exec before each file is edited (e.g. chmod, checkout).  Whitespace delimits argument words.  The string '{}' is replaced by the file name.")
	helpFlag       = flag.Bool("help", false, "show detailed help message")
	tagsFlag       = flag.String("tags", "", "comma-separated list of build tags to apply (see: go help buildconstraint)")
	templateFlag   = flag.String("t", "", "template.go file specifying the refactoring")
	transitiveFlag = flag.Bool("transitive", false, "apply refactoring to all dependencies too")
	writeFlag      = flag.Bool("w", false, "rewrite input files in place (by default, the results are printed to standard output)")
	verboseFlag    = flag.Bool("v", false, "show verbose matcher diagnostics")
)

const usage = `eg: an example-based refactoring tool.

Usage: eg -t template.go [-w] [-transitive] [-tags=tag,...] <packages>

-help            show detailed help message
-t template.go   specifies the template file (use -help to see explanation)
-w               causes files to be re-written in place.
-transitive      causes all dependencies to be refactored too.
-v               show verbose matcher diagnostics
-tags tag,...    comma-separated list of build tags to apply (see: go help buildconstraint)
-beforeedit cmd  a command to exec before each file is modified.
                 "{}" represents the name of the file.
`

func main() {
	if err := doMain(); err != nil {
		fmt.Fprintf(os.Stderr, "eg: %s\n", err)
		os.Exit(1)
	}
}

func doMain() error {
	flag.Parse()
	args := flag.Args()

	if *helpFlag {
		help := eg.Help // hide %s from vet
		fmt.Fprint(os.Stderr, help)
		os.Exit(2)
	}

	if len(args) == 0 {
		fmt.Fprint(os.Stderr, usage)
		os.Exit(1)
	}

	if *templateFlag == "" {
		return fmt.Errorf("no -t template.go file specified")
	}

	tAbs, err := filepath.Abs(*templateFlag)
	if err != nil {
		return err
	}
	template, err := os.ReadFile(tAbs)
	if err != nil {
		return err
	}

	cfg := &packages.Config{
		BuildFlags: []string{"-tags=" + *tagsFlag},
		Fset:       token.NewFileSet(),
		Mode:       packages.NeedTypesInfo | packages.NeedName | packages.NeedTypes | packages.NeedSyntax | packages.NeedImports | packages.NeedDeps | packages.NeedCompiledGoFiles,
		Tests:      true,
	}

	pkgs, err := packages.Load(cfg, args...)
	if err != nil {
		return err
	}

	tFile, err := parser.ParseFile(cfg.Fset, tAbs, template, parser.ParseComments)
	if err != nil {
		return err
	}

	// Type-check the template.
	tInfo := types.Info{
		Types:      make(map[ast.Expr]types.TypeAndValue),
		Defs:       make(map[*ast.Ident]types.Object),
		Uses:       make(map[*ast.Ident]types.Object),
		Implicits:  make(map[ast.Node]types.Object),
		Selections: make(map[*ast.SelectorExpr]*types.Selection),
		Scopes:     make(map[ast.Node]*types.Scope),
	}
	conf := types.Config{
		Importer: pkgsImporter(pkgs),
	}
	tPkg, err := conf.Check("egtemplate", cfg.Fset, []*ast.File{tFile}, &tInfo)
	if err != nil {
		return err
	}

	// Analyze the template.
	xform, err := eg.NewTransformer(cfg.Fset, tPkg, tFile, &tInfo, *verboseFlag)
	if err != nil {
		return err
	}

	// Apply it to the input packages.
	var all []*packages.Package
	if *transitiveFlag {
		packages.Visit(pkgs, nil, func(p *packages.Package) { all = append(all, p) })
	} else {
		all = pkgs
	}
	var hadErrors bool
	for _, pkg := range pkgs {
		for i, filename := range pkg.CompiledGoFiles {
			if filename == tAbs {
				// Don't rewrite the template file.
				continue
			}
			file := pkg.Syntax[i]
			n := xform.Transform(pkg.TypesInfo, pkg.Types, file)
			if n == 0 {
				continue
			}
			fmt.Fprintf(os.Stderr, "=== %s (%d matches)\n", filename, n)
			if *writeFlag {
				// Run the before-edit command (e.g. "chmod +w",  "checkout") if any.
				if *beforeeditFlag != "" {
					args := strings.Fields(*beforeeditFlag)
					// Replace "{}" with the filename, like find(1).
					for i := range args {
						if i > 0 {
							args[i] = strings.Replace(args[i], "{}", filename, -1)
						}
					}
					cmd := exec.Command(args[0], args[1:]...)
					cmd.Stdout = os.Stdout
					cmd.Stderr = os.Stderr
					if err := cmd.Run(); err != nil {
						fmt.Fprintf(os.Stderr, "Warning: edit hook %q failed (%s)\n",
							args, err)
					}
				}
				if err := eg.WriteAST(cfg.Fset, filename, file); err != nil {
					fmt.Fprintf(os.Stderr, "eg: %s\n", err)
					hadErrors = true
				}
			} else {
				format.Node(os.Stdout, cfg.Fset, file)
			}
		}
	}
	if hadErrors {
		os.Exit(1)
	}

	return nil
}

type pkgsImporter []*packages.Package

func (p pkgsImporter) Import(path string) (tpkg *types.Package, err error) {
	packages.Visit([]*packages.Package(p), func(pkg *packages.Package) bool {
		if pkg.PkgPath == path {
			tpkg = pkg.Types
			return false
		}
		return true
	}, nil)
	if tpkg != nil {
		return tpkg, nil
	}
	return nil, fmt.Errorf("package %q not found", path)
}


================================================
FILE: cmd/file2fuzz/main.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// file2fuzz converts binary files, such as those used by go-fuzz, to the Go
// fuzzing corpus format.
//
// Usage:
//
//	file2fuzz [-o output] [input...]
//
// The default behavior is to read input from stdin and write the converted
// output to stdout. If any position arguments are provided stdin is ignored
// and the arguments are assumed to be input files to convert.
//
// The -o flag provides a path to write output files to. If only one positional
// argument is specified it may be a file path or an existing directory, if there are
// multiple inputs specified it must be a directory. If a directory is provided
// the name of the file will be the SHA-256 hash of its contents.
package main

import (
	"crypto/sha256"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"path/filepath"
)

// encVersion1 is version 1 Go fuzzer corpus encoding.
var encVersion1 = "go test fuzz v1"

func encodeByteSlice(b []byte) []byte {
	return fmt.Appendf(nil, "%s\n[]byte(%q)", encVersion1, b)
}

func usage() {
	fmt.Fprintf(os.Stderr, "usage: file2fuzz [-o output] [input...]\nconverts files to Go fuzzer corpus format\n")
	fmt.Fprintf(os.Stderr, "\tinput: files to convert\n")
	fmt.Fprintf(os.Stderr, "\t-o: where to write converted file(s)\n")
	os.Exit(2)
}
func dirWriter(dir string) func([]byte) error {
	return func(b []byte) error {
		sum := fmt.Sprintf("%x", sha256.Sum256(b))
		name := filepath.Join(dir, sum)
		if err := os.MkdirAll(dir, 0777); err != nil {
			return err
		}
		if err := os.WriteFile(name, b, 0666); err != nil {
			os.Remove(name)
			return err
		}
		return nil
	}
}

func convert(inputArgs []string, outputArg string) error {
	var input []io.Reader
	if args := inputArgs; len(args) == 0 {
		input = []io.Reader{os.Stdin}
	} else {
		for _, a := range args {
			f, err := os.Open(a)
			if err != nil {
				return fmt.Errorf("unable to open %q: %s", a, err)
			}
			defer f.Close()
			if fi, err := f.Stat(); err != nil {
				return fmt.Errorf("unable to open %q: %s", a, err)
			} else if fi.IsDir() {
				return fmt.Errorf("%q is a directory, not a file", a)
			}
			input = append(input, f)
		}
	}

	var output func([]byte) error
	if outputArg == "" {
		if len(inputArgs) > 1 {
			return errors.New("-o required with multiple input files")
		}
		output = func(b []byte) error {
			_, err := os.Stdout.Write(b)
			return err
		}
	} else {
		if len(inputArgs) > 1 {
			output = dirWriter(outputArg)
		} else {
			if fi, err := os.Stat(outputArg); err != nil && !os.IsNotExist(err) {
				return fmt.Errorf("unable to open %q for writing: %s", outputArg, err)
			} else if err == nil && fi.IsDir() {
				output = dirWriter(outputArg)
			} else {
				output = func(b []byte) error {
					return os.WriteFile(outputArg, b, 0666)
				}
			}
		}
	}

	for _, f := range input {
		b, err := io.ReadAll(f)
		if err != nil {
			return fmt.Errorf("unable to read input: %s", err)
		}
		if err := output(encodeByteSlice(b)); err != nil {
			return fmt.Errorf("unable to write output: %s", err)
		}
	}

	return nil
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("file2fuzz: ")

	output := flag.String("o", "", "where to write converted file(s)")
	flag.Usage = usage
	flag.Parse()

	if err := convert(flag.Args(), *output); err != nil {
		log.Fatal(err)
	}
}


================================================
FILE: cmd/file2fuzz/main_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	if os.Getenv("GO_FILE2FUZZ_TEST_IS_FILE2FUZZ") != "" {
		main()
		os.Exit(0)
	}

	os.Exit(m.Run())
}

var f2f struct {
	once sync.Once
	path string
	err  error
}

func file2fuzz(t *testing.T, dir string, args []string, stdin string) (string, bool) {
	testenv.NeedsExec(t)

	f2f.once.Do(func() {
		f2f.path, f2f.err = os.Executable()
	})
	if f2f.err != nil {
		t.Fatal(f2f.err)
	}

	cmd := exec.Command(f2f.path, args...)
	cmd.Dir = dir
	cmd.Env = append(os.Environ(), "PWD="+dir, "GO_FILE2FUZZ_TEST_IS_FILE2FUZZ=1")
	if stdin != "" {
		cmd.Stdin = strings.NewReader(stdin)
	}
	out, err := cmd.CombinedOutput()
	if err != nil {
		return string(out), true
	}
	return string(out), false
}

func TestFile2Fuzz(t *testing.T) {
	type file struct {
		name    string
		dir     bool
		content string
	}
	tests := []struct {
		name           string
		args           []string
		stdin          string
		inputFiles     []file
		expectedStdout string
		expectedFiles  []file
		expectedError  string
	}{
		{
			name:           "stdin, stdout",
			stdin:          "hello",
			expectedStdout: "go test fuzz v1\n[]byte(\"hello\")",
		},
		{
			name:          "stdin, output file",
			stdin:         "hello",
			args:          []string{"-o", "output"},
			expectedFiles: []file{{name: "output", content: "go test fuzz v1\n[]byte(\"hello\")"}},
		},
		{
			name:          "stdin, output directory",
			stdin:         "hello",
			args:          []string{"-o", "output"},
			inputFiles:    []file{{name: "output", dir: true}},
			expectedFiles: []file{{name: "output/ffc7b87a0377262d4f77926bd235551d78e6037bbe970d81ec39ac1d95542f7b", content: "go test fuzz v1\n[]byte(\"hello\")"}},
		},
		{
			name:          "input file, output file",
			args:          []string{"-o", "output", "input"},
			inputFiles:    []file{{name: "input", content: "hello"}},
			expectedFiles: []file{{name: "output", content: "go test fuzz v1\n[]byte(\"hello\")"}},
		},
		{
			name:          "input file, output directory",
			args:          []string{"-o", "output", "input"},
			inputFiles:    []file{{name: "output", dir: true}, {name: "input", content: "hello"}},
			expectedFiles: []file{{name: "output/ffc7b87a0377262d4f77926bd235551d78e6037bbe970d81ec39ac1d95542f7b", content: "go test fuzz v1\n[]byte(\"hello\")"}},
		},
		{
			name:       "input files, output directory",
			args:       []string{"-o", "output", "input", "input-2"},
			inputFiles: []file{{name: "output", dir: true}, {name: "input", content: "hello"}, {name: "input-2", content: "hello :)"}},
			expectedFiles: []file{
				{name: "output/ffc7b87a0377262d4f77926bd235551d78e6037bbe970d81ec39ac1d95542f7b", content: "go test fuzz v1\n[]byte(\"hello\")"},
				{name: "output/28059db30ce420ff65b2c29b749804c69c601aeca21b3cbf0644244ff080d7a5", content: "go test fuzz v1\n[]byte(\"hello :)\")"},
			},
		},
		{
			name:          "input files, no output",
			args:          []string{"input", "input-2"},
			inputFiles:    []file{{name: "output", dir: true}, {name: "input", content: "hello"}, {name: "input-2", content: "hello :)"}},
			expectedError: "file2fuzz: -o required with multiple input files\n",
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			tmp, err := os.MkdirTemp(os.TempDir(), "file2fuzz")
			if err != nil {
				t.Fatalf("os.MkdirTemp failed: %s", err)
			}
			defer os.RemoveAll(tmp)
			for _, f := range tc.inputFiles {
				if f.dir {
					if err := os.Mkdir(filepath.Join(tmp, f.name), 0777); err != nil {
						t.Fatalf("failed to create test directory: %s", err)
					}
				} else {
					if err := os.WriteFile(filepath.Join(tmp, f.name), []byte(f.content), 0666); err != nil {
						t.Fatalf("failed to create test input file: %s", err)
					}
				}
			}

			out, failed := file2fuzz(t, tmp, tc.args, tc.stdin)
			if failed && tc.expectedError == "" {
				t.Fatalf("file2fuzz failed unexpectedly: %s", out)
			} else if failed && out != tc.expectedError {
				t.Fatalf("file2fuzz returned unexpected error: got %q, want %q", out, tc.expectedError)
			}
			if !failed && out != tc.expectedStdout {
				t.Fatalf("file2fuzz unexpected stdout: got %q, want %q", out, tc.expectedStdout)
			}

			for _, f := range tc.expectedFiles {
				c, err := os.ReadFile(filepath.Join(tmp, f.name))
				if err != nil {
					t.Fatalf("failed to read expected output file %q: %s", f.name, err)
				}
				if string(c) != f.content {
					t.Fatalf("expected output file %q contains unexpected content: got %s, want %s", f.name, string(c), f.content)
				}
			}
		})
	}
}


================================================
FILE: cmd/fiximports/main.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The fiximports command fixes import declarations to use the canonical
// import path for packages that have an "import comment" as defined by
// https://golang.org/s/go14customimport.
//
// # Background
//
// The Go 1 custom import path mechanism lets the maintainer of a
// package give it a stable name by which clients may import and "go
// get" it, independent of the underlying version control system (such
// as Git) or server (such as github.com) that hosts it.  Requests for
// the custom name are redirected to the underlying name.  This allows
// packages to be migrated from one underlying server or system to
// another without breaking existing clients.
//
// Because this redirect mechanism creates aliases for existing
// packages, it's possible for a single program to import the same
// package by its canonical name and by an alias.  The resulting
// executable will contain two copies of the package, which is wasteful
// at best and incorrect at worst.
//
// To avoid this, "go build" reports an error if it encounters a special
// comment like the one below, and if the import path in the comment
// does not match the path of the enclosing package relative to
// GOPATH/src:
//
//	     $ grep ^package $GOPATH/src/github.com/bob/vanity/foo/foo.go
//		package foo // import "vanity.com/foo"
//
// The error from "go build" indicates that the package canonically
// known as "vanity.com/foo" is locally installed under the
// non-canonical name "github.com/bob/vanity/foo".
//
// # Usage
//
// When a package that you depend on introduces a custom import comment,
// and your workspace imports it by the non-canonical name, your build
// will stop working as soon as you update your copy of that package
// using "go get -u".
//
// The purpose of the fiximports tool is to fix up all imports of the
// non-canonical path within a Go workspace, replacing them with imports
// of the canonical path.  Following a run of fiximports, the workspace
// will no longer depend on the non-canonical copy of the package, so it
// should be safe to delete.  It may be necessary to run "go get -u"
// again to ensure that the package is locally installed under its
// canonical path, if it was not already.
//
// The fiximports tool operates locally; it does not make HTTP requests
// and does not discover new custom import comments.  It only operates
// on non-canonical packages present in your workspace.
//
// The -baddomains flag is a list of domain names that should always be
// considered non-canonical.  You can use this if you wish to make sure
// that you no longer have any dependencies on packages from that
// domain, even those that do not yet provide a canonical import path
// comment.  For example, the default value of -baddomains includes the
// moribund code hosting site code.google.com, so fiximports will report
// an error for each import of a package from this domain remaining
// after canonicalization.
//
// To see the changes fiximports would make without applying them, use
// the -n flag.
package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"io"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
)

// flags
var (
	dryrun     = flag.Bool("n", false, "dry run: show changes, but don't apply them")
	badDomains = flag.String("baddomains", "code.google.com",
		"a comma-separated list of domains from which packages should not be imported")
	replaceFlag = flag.String("replace", "",
		"a comma-separated list of noncanonical=canonical pairs of package paths.  If both items in a pair end with '...', they are treated as path prefixes.")
)

// seams for testing
var (
	stderr    io.Writer = os.Stderr
	writeFile           = os.WriteFile
)

const usage = `fiximports: rewrite import paths to use canonical package names.

Usage: fiximports [-n] package...

The package... arguments specify a list of packages
in the style of the go tool; see "go help packages".
Hint: use "all" or "..." to match the entire workspace.

For details, see https://pkg.go.dev/golang.org/x/tools/cmd/fiximports

Flags:
  -n:	       dry run: show changes, but don't apply them
  -baddomains  a comma-separated list of domains from which packages
               should not be imported
`

func main() {
	flag.Parse()

	if len(flag.Args()) == 0 {
		fmt.Fprint(stderr, usage)
		os.Exit(1)
	}
	if !fiximports(flag.Args()...) {
		os.Exit(1)
	}
}

type canonicalName struct{ path, name string }

// fiximports fixes imports in the specified packages.
// Invariant: a false result implies an error was already printed.
func fiximports(packages ...string) bool {
	// importedBy is the transpose of the package import graph.
	importedBy := make(map[string]map[*listPackage]bool)

	// addEdge adds an edge to the import graph.
	addEdge := func(from *listPackage, to string) {
		if to == "C" || to == "unsafe" {
			return // fake
		}
		pkgs := importedBy[to]
		if pkgs == nil {
			pkgs = make(map[*listPackage]bool)
			importedBy[to] = pkgs
		}
		pkgs[from] = true
	}

	// List metadata for all packages in the workspace.
	pkgs, err := list("...")
	if err != nil {
		fmt.Fprintf(stderr, "importfix: %v\n", err)
		return false
	}

	// packageName maps each package's path to its name.
	packageName := make(map[string]string)
	for _, p := range pkgs {
		packageName[p.ImportPath] = p.Name
	}

	// canonical maps each non-canonical package path to
	// its canonical path and name.
	// A present nil value indicates that the canonical package
	// is unknown: hosted on a bad domain with no redirect.
	canonical := make(map[string]canonicalName)
	domains := strings.Split(*badDomains, ",")

	type replaceItem struct {
		old, new    string
		matchPrefix bool
	}
	var replace []replaceItem
	for pair := range strings.SplitSeq(*replaceFlag, ",") {
		if pair == "" {
			continue
		}
		words := strings.Split(pair, "=")
		if len(words) != 2 {
			fmt.Fprintf(stderr, "importfix: -replace: %q is not of the form \"canonical=noncanonical\".\n", pair)
			return false
		}
		replace = append(replace, replaceItem{
			old: strings.TrimSuffix(words[0], "..."),
			new: strings.TrimSuffix(words[1], "..."),
			matchPrefix: strings.HasSuffix(words[0], "...") &&
				strings.HasSuffix(words[1], "..."),
		})
	}

	// Find non-canonical packages and populate importedBy graph.
	for _, p := range pkgs {
		if p.Error != nil {
			msg := p.Error.Err
			if strings.Contains(msg, "code in directory") &&
				strings.Contains(msg, "expects import") {
				// don't show the very errors we're trying to fix
			} else {
				fmt.Fprintln(stderr, p.Error)
			}
		}

		for _, imp := range p.Imports {
			addEdge(p, imp)
		}
		for _, imp := range p.TestImports {
			addEdge(p, imp)
		}
		for _, imp := range p.XTestImports {
			addEdge(p, imp)
		}

		// Does package have an explicit import comment?
		if p.ImportComment != "" {
			if p.ImportComment != p.ImportPath {
				canonical[p.ImportPath] = canonicalName{
					path: p.ImportComment,
					name: p.Name,
				}
			}
		} else {
			// Is package matched by a -replace item?
			var newPath string
			for _, item := range replace {
				if item.matchPrefix {
					if strings.HasPrefix(p.ImportPath, item.old) {
						newPath = item.new + p.ImportPath[len(item.old):]
						break
					}
				} else if p.ImportPath == item.old {
					newPath = item.new
					break
				}
			}
			if newPath != "" {
				newName := packageName[newPath]
				if newName == "" {
					newName = filepath.Base(newPath) // a guess
				}
				canonical[p.ImportPath] = canonicalName{
					path: newPath,
					name: newName,
				}
				continue
			}

			// Is package matched by a -baddomains item?
			for _, domain := range domains {
				slash := strings.Index(p.ImportPath, "/")
				if slash < 0 {
					continue // no slash: standard package
				}
				if p.ImportPath[:slash] == domain {
					// Package comes from bad domain and has no import comment.
					// Report an error each time this package is imported.
					canonical[p.ImportPath] = canonicalName{}

					// TODO(adonovan): should we make an HTTP request to
					// see if there's an HTTP redirect, a "go-import" meta tag,
					// or an import comment in the latest revision?
					// It would duplicate a lot of logic from "go get".
				}
				break
			}
		}
	}

	// Find all clients (direct importers) of canonical packages.
	// These are the packages that need fixing up.
	clients := make(map[*listPackage]bool)
	for path := range canonical {
		for client := range importedBy[path] {
			clients[client] = true
		}
	}

	// Restrict rewrites to the set of packages specified by the user.
	if len(packages) == 1 && (packages[0] == "all" || packages[0] == "...") {
		// no restriction
	} else {
		pkgs, err := list(packages...)
		if err != nil {
			fmt.Fprintf(stderr, "importfix: %v\n", err)
			return false
		}
		seen := make(map[string]bool)
		for _, p := range pkgs {
			seen[p.ImportPath] = true
		}
		for client := range clients {
			if !seen[client.ImportPath] {
				delete(clients, client)
			}
		}
	}

	// Rewrite selected client packages.
	ok := true
	for client := range clients {
		if !rewritePackage(client, canonical) {
			ok = false

			// There were errors.
			// Show direct and indirect imports of client.
			seen := make(map[string]bool)
			var direct, indirect []string
			for p := range importedBy[client.ImportPath] {
				direct = append(direct, p.ImportPath)
				seen[p.ImportPath] = true
			}

			var visit func(path string)
			visit = func(path string) {
				for q := range importedBy[path] {
					qpath := q.ImportPath
					if !seen[qpath] {
						seen[qpath] = true
						indirect = append(indirect, qpath)
						visit(qpath)
					}
				}
			}

			if direct != nil {
				fmt.Fprintf(stderr, "\timported directly by:\n")
				sort.Strings(direct)
				for _, path := range direct {
					fmt.Fprintf(stderr, "\t\t%s\n", path)
					visit(path)
				}

				if indirect != nil {
					fmt.Fprintf(stderr, "\timported indirectly by:\n")
					sort.Strings(indirect)
					for _, path := range indirect {
						fmt.Fprintf(stderr, "\t\t%s\n", path)
					}
				}
			}
		}
	}

	return ok
}

// Invariant: false result => error already printed.
func rewritePackage(client *listPackage, canonical map[string]canonicalName) bool {
	ok := true

	used := make(map[string]bool)
	var filenames []string
	filenames = append(filenames, client.GoFiles...)
	filenames = append(filenames, client.TestGoFiles...)
	filenames = append(filenames, client.XTestGoFiles...)
	var first bool
	for _, filename := range filenames {
		if !first {
			first = true
			fmt.Fprintf(stderr, "%s\n", client.ImportPath)
		}
		err := rewriteFile(filepath.Join(client.Dir, filename), canonical, used)
		if err != nil {
			fmt.Fprintf(stderr, "\tERROR: %v\n", err)
			ok = false
		}
	}

	// Show which imports were renamed in this package.
	var keys []string
	for key := range used {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	for _, key := range keys {
		if p := canonical[key]; p.path != "" {
			fmt.Fprintf(stderr, "\tfixed: %s -> %s\n", key, p.path)
		} else {
			fmt.Fprintf(stderr, "\tERROR: %s has no import comment\n", key)
			ok = false
		}
	}

	return ok
}

// rewriteFile reads, modifies, and writes filename, replacing all imports
// of packages P in canonical by canonical[P].
// It records in used which canonical packages were imported.
// used[P]=="" indicates that P was imported but its canonical path is unknown.
func rewriteFile(filename string, canonical map[string]canonicalName, used map[string]bool) error {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, filename, nil, parser.ParseComments)
	if err != nil {
		return err
	}
	var changed bool
	for _, imp := range f.Imports {
		impPath, err := strconv.Unquote(imp.Path.Value)
		if err != nil {
			log.Printf("%s: bad import spec %q: %v",
				fset.Position(imp.Pos()), imp.Path.Value, err)
			continue
		}
		canon, ok := canonical[impPath]
		if !ok {
			continue // import path is canonical
		}

		used[impPath] = true

		if canon.path == "" {
			// The canonical path is unknown (a -baddomain).
			// Show the offending import.
			// TODO(adonovan): should we show the actual source text?
			fmt.Fprintf(stderr, "\t%s:%d: import %q\n",
				shortPath(filename),
				fset.Position(imp.Pos()).Line, impPath)
			continue
		}

		changed = true

		imp.Path.Value = strconv.Quote(canon.path)

		// Add a renaming import if necessary.
		//
		// This is a guess at best.  We can't see whether a 'go
		// get' of the canonical import path would have the same
		// name or not.  Assume it's the last segment.
		newBase := path.Base(canon.path)
		if imp.Name == nil && newBase != canon.name {
			imp.Name = &ast.Ident{Name: canon.name}
		}
	}

	if changed && !*dryrun {
		var buf bytes.Buffer
		if err := format.Node(&buf, fset, f); err != nil {
			return fmt.Errorf("%s: couldn't format file: %v", filename, err)
		}
		return writeFile(filename, buf.Bytes(), 0644)
	}

	return nil
}

// listPackage corresponds to the output of go list -json,
// but only the fields we need.
type listPackage struct {
	Name          string
	Dir           string
	ImportPath    string
	GoFiles       []string
	TestGoFiles   []string
	XTestGoFiles  []string
	Imports       []string
	TestImports   []string
	XTestImports  []string
	ImportComment string
	Error         *packageError // error loading package
}

// A packageError describes an error loading information about a package.
type packageError struct {
	ImportStack []string // shortest path from package named on command line to this one
	Pos         string   // position of error
	Err         string   // the error itself
}

func (e packageError) Error() string {
	if e.Pos != "" {
		return e.Pos + ": " + e.Err
	}
	return e.Err
}

// list runs 'go list' with the specified arguments and returns the
// metadata for matching packages.
func list(args ...string) ([]*listPackage, error) {
	cmd := exec.Command("go", append([]string{"list", "-e", "-json"}, args...)...)
	cmd.Stdout = new(bytes.Buffer)
	cmd.Stderr = stderr
	if err := cmd.Run(); err != nil {
		return nil, err
	}

	dec := json.NewDecoder(cmd.Stdout.(io.Reader))
	var pkgs []*listPackage
	for {
		var p listPackage
		if err := dec.Decode(&p); err == io.EOF {
			break
		} else if err != nil {
			return nil, err
		}
		pkgs = append(pkgs, &p)
	}
	return pkgs, nil
}

// cwd contains the current working directory of the tool.
//
// It is initialized directly so that its value will be set for any other
// package variables or init functions that depend on it, such as the gopath
// variable in main_test.go.
var cwd string = func() string {
	cwd, err := os.Getwd()
	if err != nil {
		log.Fatalf("os.Getwd: %v", err)
	}
	return cwd
}()

// shortPath returns an absolute or relative name for path, whatever is shorter.
// Plundered from $GOROOT/src/cmd/go/build.go.
func shortPath(path string) string {
	if rel, err := filepath.Rel(cwd, path); err == nil && len(rel) < len(path) {
		return rel
	}
	return path
}


================================================
FILE: cmd/fiximports/main_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package main

import (
	"bytes"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

// TODO(adonovan):
// - test introduction of renaming imports.
// - test induced failures of rewriteFile.

// Guide to the test packages:
//
// new.com/one		-- canonical name for old.com/one
// old.com/one		-- non-canonical; has import comment "new.com/one"
// old.com/bad		-- has a parse error
// fruit.io/orange	\
// fruit.io/banana	 } orange -> pear -> banana -> titanic.biz/bar
// fruit.io/pear	/
// titanic.biz/bar	-- domain is sinking; package has jumped ship to new.com/bar
// titanic.biz/foo	-- domain is sinking but package has no import comment yet

var gopath = filepath.Join(cwd, "testdata")

func init() {
	if err := os.Setenv("GOPATH", gopath); err != nil {
		log.Fatal(err)
	}

	// This test currently requires GOPATH mode.
	// Explicitly disabling module mode should suffix, but
	// we'll also turn off GOPROXY just for good measure.
	if err := os.Setenv("GO111MODULE", "off"); err != nil {
		log.Fatal(err)
	}
	if err := os.Setenv("GOPROXY", "off"); err != nil {
		log.Fatal(err)
	}
}

func TestFixImports(t *testing.T) {
	if os.Getenv("GO_BUILDER_NAME") == "plan9-arm" {
		t.Skipf("skipping test that times out on plan9-arm; see https://go.dev/issue/50775")
	}
	testenv.NeedsTool(t, "go")

	defer func() {
		stderr = os.Stderr
		*badDomains = "code.google.com"
		*replaceFlag = ""
	}()

	for i, test := range []struct {
		packages    []string // packages to rewrite, "go list" syntax
		badDomains  string   // -baddomains flag
		replaceFlag string   // -replace flag
		wantOK      bool
		wantStderr  string
		wantRewrite map[string]string
	}{
		// #0. No errors.
		{
			packages:   []string{"all"},
			badDomains: "code.google.com",
			wantOK:     true,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
fruit.io/banana
	fixed: old.com/one -> new.com/one
	fixed: titanic.biz/bar -> new.com/bar
`,
			wantRewrite: map[string]string{
				"$GOPATH/src/fruit.io/banana/banana.go": `package banana

import (
	_ "new.com/bar"
	_ "new.com/one"
	_ "titanic.biz/foo"
)`,
			},
		},
		// #1. No packages needed rewriting.
		{
			packages:   []string{"titanic.biz/...", "old.com/...", "new.com/..."},
			badDomains: "code.google.com",
			wantOK:     true,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
`,
		},
		// #2. Some packages without import comments matched bad domains.
		{
			packages:   []string{"all"},
			badDomains: "titanic.biz",
			wantOK:     false,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
fruit.io/banana
	testdata/src/fruit.io/banana/banana.go:6: import "titanic.biz/foo"
	fixed: old.com/one -> new.com/one
	fixed: titanic.biz/bar -> new.com/bar
	ERROR: titanic.biz/foo has no import comment
	imported directly by:
		fruit.io/pear
	imported indirectly by:
		fruit.io/orange
`,
			wantRewrite: map[string]string{
				"$GOPATH/src/fruit.io/banana/banana.go": `package banana

import (
	_ "new.com/bar"
	_ "new.com/one"
	_ "titanic.biz/foo"
)`,
			},
		},
		// #3. The -replace flag lets user supply missing import comments.
		{
			packages:    []string{"all"},
			replaceFlag: "titanic.biz/foo=new.com/foo",
			wantOK:      true,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
fruit.io/banana
	fixed: old.com/one -> new.com/one
	fixed: titanic.biz/bar -> new.com/bar
	fixed: titanic.biz/foo -> new.com/foo
`,
			wantRewrite: map[string]string{
				"$GOPATH/src/fruit.io/banana/banana.go": `package banana

import (
	_ "new.com/bar"
	_ "new.com/foo"
	_ "new.com/one"
)`,
			},
		},
		// #4. The -replace flag supports wildcards.
		//     An explicit import comment takes precedence.
		{
			packages:    []string{"all"},
			replaceFlag: "titanic.biz/...=new.com/...",
			wantOK:      true,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
fruit.io/banana
	fixed: old.com/one -> new.com/one
	fixed: titanic.biz/bar -> new.com/bar
	fixed: titanic.biz/foo -> new.com/foo
`,
			wantRewrite: map[string]string{
				"$GOPATH/src/fruit.io/banana/banana.go": `package banana

import (
	_ "new.com/bar"
	_ "new.com/foo"
	_ "new.com/one"
)`,
			},
		},
		// #5. The -replace flag trumps -baddomains.
		{
			packages:    []string{"all"},
			badDomains:  "titanic.biz",
			replaceFlag: "titanic.biz/foo=new.com/foo",
			wantOK:      true,
			wantStderr: `
testdata/src/old.com/bad/bad.go:2:43: expected 'package', found 'EOF'
fruit.io/banana
	fixed: old.com/one -> new.com/one
	fixed: titanic.biz/bar -> new.com/bar
	fixed: titanic.biz/foo -> new.com/foo
`,
			wantRewrite: map[string]string{
				"$GOPATH/src/fruit.io/banana/banana.go": `package banana

import (
	_ "new.com/bar"
	_ "new.com/foo"
	_ "new.com/one"
)`,
			},
		},
	} {
		*badDomains = test.badDomains
		*replaceFlag = test.replaceFlag

		stderr = new(bytes.Buffer)
		gotRewrite := make(map[string]string)
		writeFile = func(filename string, content []byte, mode os.FileMode) error {
			filename = strings.Replace(filename, gopath, "$GOPATH", 1)
			filename = filepath.ToSlash(filename)
			gotRewrite[filename] = string(bytes.TrimSpace(content))
			return nil
		}

		if runtime.GOOS == "windows" {
			test.wantStderr = strings.Replace(test.wantStderr, `testdata/src/old.com/bad/bad.go`, `testdata\src\old.com\bad\bad.go`, -1)
			test.wantStderr = strings.Replace(test.wantStderr, `testdata/src/fruit.io/banana/banana.go`, `testdata\src\fruit.io\banana\banana.go`, -1)
		}
		test.wantStderr = strings.TrimSpace(test.wantStderr)

		// Check status code.
		if fiximports(test.packages...) != test.wantOK {
			t.Errorf("#%d. fiximports() = %t", i, !test.wantOK)
		}

		// Compare stderr output.
		if got := strings.TrimSpace(stderr.(*bytes.Buffer).String()); got != test.wantStderr {
			if strings.Contains(got, "vendor/golang_org/x/text/unicode/norm") {
				t.Skip("skipping known-broken test; see golang.org/issue/17417")
			}
			t.Errorf("#%d. stderr: got <<\n%s\n>>, want <<\n%s\n>>",
				i, got, test.wantStderr)
		}

		// Compare rewrites.
		for k, v := range gotRewrite {
			if test.wantRewrite[k] != v {
				t.Errorf("#%d. rewrite[%s] = <<%s>>, want <<%s>>",
					i, k, v, test.wantRewrite[k])
			}
			delete(test.wantRewrite, k)
		}
		for k, v := range test.wantRewrite {
			t.Errorf("#%d. rewrite[%s] missing, want <<%s>>", i, k, v)
		}
	}
}

// TestDryRun tests that the -n flag suppresses calls to writeFile.
func TestDryRun(t *testing.T) {
	if os.Getenv("GO_BUILDER_NAME") == "plan9-arm" {
		t.Skipf("skipping test that times out on plan9-arm; see https://go.dev/issue/50775")
	}
	testenv.NeedsTool(t, "go")

	*dryrun = true
	defer func() { *dryrun = false }() // restore
	stderr = new(bytes.Buffer)
	writeFile = func(filename string, content []byte, mode os.FileMode) error {
		t.Fatalf("writeFile(%s) called in dryrun mode", filename)
		return nil
	}

	if !fiximports("all") {
		t.Fatalf("fiximports failed: %s", stderr)
	}
}


================================================
FILE: cmd/fiximports/testdata/src/fruit.io/banana/banana.go
================================================
package banana

import (
	_ "old.com/one"
	_ "titanic.biz/bar"
	_ "titanic.biz/foo"
)


================================================
FILE: cmd/fiximports/testdata/src/fruit.io/orange/orange.go
================================================
package orange

import _ "fruit.io/pear"


================================================
FILE: cmd/fiximports/testdata/src/fruit.io/pear/pear.go
================================================
package pear

import _ "fruit.io/banana"


================================================
FILE: cmd/fiximports/testdata/src/new.com/one/one.go
================================================
package one // import "new.com/one"


================================================
FILE: cmd/fiximports/testdata/src/old.com/bad/bad.go
================================================
// This ill-formed Go source file is here to ensure the tool is robust
// against bad packages in the workspace.


================================================
FILE: cmd/fiximports/testdata/src/old.com/one/one.go
================================================
package one // import "new.com/one"


================================================
FILE: cmd/fiximports/testdata/src/titanic.biz/bar/bar.go
================================================
// This package is moving to new.com too.
package bar // import "new.com/bar"


================================================
FILE: cmd/fiximports/testdata/src/titanic.biz/foo/foo.go
================================================
// This package hasn't jumped ship yet.
package foo


================================================
FILE: cmd/go-contrib-init/contrib.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The go-contrib-init command helps new Go contributors get their development
// environment set up for the Go contribution process.
//
// It aims to be a complement or alternative to https://golang.org/doc/contribute.html.
package main

import (
	"bytes"
	"flag"
	"fmt"
	"go/build"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
)

var (
	repo = flag.String("repo", detectrepo(), "Which go repo you want to contribute to. Use \"go\" for the core, or e.g. \"net\" for golang.org/x/net/*")
	dry  = flag.Bool("dry-run", false, "Fail with problems instead of trying to fix things.")
)

func main() {
	log.SetFlags(0)
	flag.Parse()

	checkCLA()
	checkGoroot()
	checkWorkingDir()
	checkGitOrigin()
	checkGitCodeReview()
	fmt.Print("All good. Happy hacking!\n" +
		"Remember to squash your revised commits and preserve the magic Change-Id lines.\n" +
		"Next steps: https://golang.org/doc/contribute.html#commit_changes\n")
}

func detectrepo() string {
	wd, err := os.Getwd()
	if err != nil {
		return "go"
	}

	for _, path := range filepath.SplitList(build.Default.GOPATH) {
		rightdir := filepath.Join(path, "src", "golang.org", "x") + string(os.PathSeparator)
		if strings.HasPrefix(wd, rightdir) {
			tail := wd[len(rightdir):]
			end := strings.Index(tail, string(os.PathSeparator))
			if end > 0 {
				repo := tail[:end]
				return repo
			}
		}
	}

	return "go"
}

var googleSourceRx = regexp.MustCompile(`(?m)^(go|go-review)?\.googlesource.com\b`)

func checkCLA() {
	slurp, err := os.ReadFile(cookiesFile())
	if err != nil && !os.IsNotExist(err) {
		log.Fatal(err)
	}
	if googleSourceRx.Match(slurp) {
		// Probably good.
		return
	}
	log.Fatal("Your .gitcookies file isn't configured.\n" +
		"Next steps:\n" +
		"  * Submit a CLA (https://golang.org/doc/contribute.html#cla) if not done\n" +
		"  * Go to https://go.googlesource.com/ and click \"Generate Password\" at the top,\n" +
		"    then follow instructions.\n" +
		"  * Run go-contrib-init again.\n")
}

func expandUser(s string) string {
	env := "HOME"
	if runtime.GOOS == "windows" {
		env = "USERPROFILE"
	} else if runtime.GOOS == "plan9" {
		env = "home"
	}
	home := os.Getenv(env)
	if home == "" {
		return s
	}

	if len(s) >= 2 && s[0] == '~' && os.IsPathSeparator(s[1]) {
		if runtime.GOOS == "windows" {
			s = filepath.ToSlash(filepath.Join(home, s[2:]))
		} else {
			s = filepath.Join(home, s[2:])
		}
	}
	return os.Expand(s, func(env string) string {
		if env == "HOME" {
			return home
		}
		return os.Getenv(env)
	})
}

func cookiesFile() string {
	out, _ := exec.Command("git", "config", "http.cookiefile").Output()
	if s := strings.TrimSpace(string(out)); s != "" {
		if strings.HasPrefix(s, "~") {
			s = expandUser(s)
		}
		return s
	}
	if runtime.GOOS == "windows" {
		return filepath.Join(os.Getenv("USERPROFILE"), ".gitcookies")
	}
	return filepath.Join(os.Getenv("HOME"), ".gitcookies")
}

func checkGoroot() {
	v := os.Getenv("GOROOT")
	if v == "" {
		return
	}
	if *repo == "go" {
		if strings.HasPrefix(v, "/usr/") {
			log.Fatalf("Your GOROOT environment variable is set to %q\n"+
				"This is almost certainly not what you want. Either unset\n"+
				"your GOROOT or set it to the path of your development version\n"+
				"of Go.", v)
		}
		slurp, err := os.ReadFile(filepath.Join(v, "VERSION"))
		if err == nil {
			slurp = bytes.TrimSpace(slurp)
			log.Fatalf("Your GOROOT environment variable is set to %q\n"+
				"But that path is to a binary release of Go, with VERSION file %q.\n"+
				"You should hack on Go in a fresh checkout of Go. Fix or unset your GOROOT.\n",
				v, slurp)
		}
	}
}

func checkWorkingDir() {
	wd, err := os.Getwd()
	if err != nil {
		log.Fatal(err)
	}
	if *repo == "go" {
		if inGoPath(wd) {
			log.Fatalf(`You can't work on Go from within your GOPATH. Please checkout Go outside of your GOPATH

Current directory: %s
GOPATH: %s
`, wd, os.Getenv("GOPATH"))
		}
		return
	}
}

func inGoPath(wd string) bool {
	if os.Getenv("GOPATH") == "" {
		return false
	}

	for _, path := range filepath.SplitList(os.Getenv("GOPATH")) {
		if strings.HasPrefix(wd, filepath.Join(path, "src")) {
			return true
		}
	}

	return false
}

// mostly check that they didn't clone from github
func checkGitOrigin() {
	if _, err := exec.LookPath("git"); err != nil {
		log.Fatalf("You don't appear to have git installed. Do that.")
	}
	wantRemote := "https://go.googlesource.com/" + *repo
	remotes, err := exec.Command("git", "remote", "-v").Output()
	if err != nil {
		msg := cmdErr(err)
		if strings.Contains(msg, "Not a git repository") {
			log.Fatalf("Your current directory is not in a git checkout of %s", wantRemote)
		}
		log.Fatalf("Error running git remote -v: %v", msg)
	}
	matches := 0
	for line := range strings.SplitSeq(string(remotes), "\n") {
		line = strings.TrimSpace(line)
		if !strings.HasPrefix(line, "origin") {
			continue
		}
		if !strings.Contains(line, wantRemote) {
			curRemote := strings.Fields(strings.TrimPrefix(line, "origin"))[0]
			// TODO: if not in dryRun mode, just fix it?
			log.Fatalf("Current directory's git was cloned from %q; origin should be %q", curRemote, wantRemote)
		}
		matches++
	}
	if matches == 0 {
		log.Fatalf("git remote -v output didn't contain expected %q. Got:\n%s", wantRemote, remotes)
	}
}

func cmdErr(err error) string {
	if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
		return fmt.Sprintf("%s: %s", err, ee.Stderr)
	}
	return fmt.Sprint(err)
}

func checkGitCodeReview() {
	if _, err := exec.LookPath("git-codereview"); err != nil {
		if *dry {
			log.Fatalf("You don't appear to have git-codereview tool. While this is technically optional,\n" +
				"almost all Go contributors use it. Our documentation and this tool assume it is used.\n" +
				"To install it, run:\n\n\t$ go get golang.org/x/review/git-codereview\n\n(Then run go-contrib-init again)")
		}
		err := exec.Command("go", "get", "golang.org/x/review/git-codereview").Run()
		if err != nil {
			log.Fatalf("Error running go get golang.org/x/review/git-codereview: %v", cmdErr(err))
		}
		log.Printf("Installed git-codereview (ran `go get golang.org/x/review/git-codereview`)")
	}
	missing := false
	for _, cmd := range []string{"change", "gofmt", "mail", "pending", "submit", "sync"} {
		v, _ := exec.Command("git", "config", "alias."+cmd).Output()
		if strings.Contains(string(v), "codereview") {
			continue
		}
		if *dry {
			log.Printf("Missing alias. Run:\n\t$ git config alias.%s \"codereview %s\"", cmd, cmd)
			missing = true
		} else {
			err := exec.Command("git", "config", "alias."+cmd, "codereview "+cmd).Run()
			if err != nil {
				log.Fatalf("Error setting alias.%s: %v", cmd, cmdErr(err))
			}
		}
	}
	if missing {
		log.Fatalf("Missing aliases. (While optional, this tool assumes you use them.)")
	}
}


================================================
FILE: cmd/go-contrib-init/contrib_test.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"errors"
	"os"
	"os/exec"
	"runtime"
	"testing"
)

func TestExpandUser(t *testing.T) {
	env := "HOME"
	if runtime.GOOS == "windows" {
		env = "USERPROFILE"
	} else if runtime.GOOS == "plan9" {
		env = "home"
	}

	oldenv := os.Getenv(env)
	os.Setenv(env, "/home/gopher")
	defer os.Setenv(env, oldenv)

	tests := []struct {
		input string
		want  string
	}{
		{input: "~/foo", want: "/home/gopher/foo"},
		{input: "${HOME}/foo", want: "/home/gopher/foo"},
		{input: "/~/foo", want: "/~/foo"},
	}
	for _, tt := range tests {
		got := expandUser(tt.input)
		if got != tt.want {
			t.Fatalf("want %q, but %q", tt.want, got)
		}
	}
}

func TestCmdErr(t *testing.T) {
	tests := []struct {
		input error
		want  string
	}{
		{input: errors.New("cmd error"), want: "cmd error"},
		{input: &exec.ExitError{ProcessState: nil, Stderr: nil}, want: "<nil>"},
		{input: &exec.ExitError{ProcessState: nil, Stderr: []byte("test")}, want: "<nil>: test"},
	}

	for i, tt := range tests {
		got := cmdErr(tt.input)
		if got != tt.want {
			t.Fatalf("%d. got %q, want %q", i, got, tt.want)
		}
	}
}


================================================
FILE: cmd/godex/doc.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The godex command prints (dumps) exported information of packages
// or selected package objects.
//
// In contrast to godoc, godex extracts this information from compiled
// object files. Hence the exported data is truly what a compiler will
// see, at the cost of missing commentary.
//
// Usage: godex [flags] {path[.name]}
//
// Each argument must be a (possibly partial) package path, optionally
// followed by a dot and the name of a package object:
//
//	godex math
//	godex math.Sin
//	godex math.Sin fmt.Printf
//	godex go/types
//
// godex automatically tries all possible package path prefixes if only a
// partial package path is given. For instance, for the path "go/types",
// godex prepends "golang.org/x/tools".
//
// The prefixes are computed by searching the directories specified by
// the GOROOT and GOPATH environment variables (and by excluding the
// build OS- and architecture-specific directory names from the path).
// The search order is depth-first and alphabetic; for a partial path
// "foo", a package "a/foo" is found before "b/foo".
//
// Absolute and relative paths may be provided, which disable automatic
// prefix generation:
//
//	godex $GOROOT/pkg/darwin_amd64/sort
//	godex ./sort
//
// All but the last path element may contain dots; a dot in the last path
// element separates the package path from the package object name. If the
// last path element contains a dot, terminate the argument with another
// dot (indicating an empty object name). For instance, the path for a
// package foo.bar would be specified as in:
//
//	godex foo.bar.
//
// The flags are:
//
//	-s=""
//		only consider packages from src, where src is one of the supported compilers
//	-v=false
//		verbose mode
//
// The following sources (-s arguments) are supported:
//
//	gc
//		gc-generated object files
//	gccgo
//		gccgo-generated object files
//	gccgo-new
//		gccgo-generated object files using a condensed format (experimental)
//	source
//		(uncompiled) source code (not yet implemented)
//
// If no -s argument is provided, godex will try to find a matching source.
package main // import "golang.org/x/tools/cmd/godex"

// BUG(gri): support for -s=source is not yet implemented
// BUG(gri): gccgo-importing appears to have occasional problems stalling godex; try -s=gc as work-around


================================================
FILE: cmd/godex/gc.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements access to gc-generated export data.

package main

import (
	"go/importer"
	"go/token"
)

func init() {
	register("gc", importer.ForCompiler(token.NewFileSet(), "gc", nil))
}


================================================
FILE: cmd/godex/gccgo.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements access to gccgo-generated export data.

package main

import (
	"go/importer"
	"go/token"
	"go/types"
)

func init() {
	register("gccgo", importer.ForCompiler(token.NewFileSet(), "gccgo", nil))
}

// Print the extra gccgo compiler data for this package, if it exists.
func (p *printer) printGccgoExtra(pkg *types.Package) {
	// Disabled for now.
	// TODO(gri) address this at some point.

	// if initdata, ok := initmap[pkg]; ok {
	// 	p.printf("/*\npriority %d\n", initdata.Priority)

	// 	p.printDecl("init", len(initdata.Inits), func() {
	// 		for _, init := range initdata.Inits {
	// 			p.printf("%s %s %d\n", init.Name, init.InitFunc, init.Priority)
	// 		}
	// 	})

	// 	p.print("*/\n")
	// }
}


================================================
FILE: cmd/godex/godex.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"errors"
	"flag"
	"fmt"
	"go/build"
	"go/types"
	"os"
	"path/filepath"
	"strings"
)

var (
	source  = flag.String("s", "", "only consider packages from src, where src is one of the supported compilers")
	verbose = flag.Bool("v", false, "verbose mode")
)

// lists of registered sources and corresponding importers
var (
	sources         []string
	importers       []types.Importer
	errImportFailed = errors.New("import failed")
)

func usage() {
	fmt.Fprintln(os.Stderr, "usage: godex [flags] {path|qualifiedIdent}")
	flag.PrintDefaults()
	os.Exit(2)
}

func report(msg string) {
	fmt.Fprintln(os.Stderr, "error: "+msg)
	os.Exit(2)
}

func main() {
	flag.Usage = usage
	flag.Parse()

	if flag.NArg() == 0 {
		report("no package name, path, or file provided")
	}

	var imp types.Importer = new(tryImporters)
	if *source != "" {
		imp = lookup(*source)
		if imp == nil {
			report("source (-s argument) must be one of: " + strings.Join(sources, ", "))
		}
	}

	for _, arg := range flag.Args() {
		path, name := splitPathIdent(arg)
		logf("\tprocessing %q: path = %q, name = %s\n", arg, path, name)

		// generate possible package path prefixes
		// (at the moment we do this for each argument - should probably cache the generated prefixes)
		prefixes := make(chan string)
		go genPrefixes(prefixes, !filepath.IsAbs(path) && !build.IsLocalImport(path))

		// import package
		pkg, err := tryPrefixes(prefixes, path, imp)
		if err != nil {
			logf("\t=> ignoring %q: %s\n", path, err)
			continue
		}

		// filter objects if needed
		var filter func(types.Object) bool
		if name != "" {
			filter = func(obj types.Object) bool {
				// TODO(gri) perhaps use regular expression matching here?
				return obj.Name() == name
			}
		}

		// print contents
		print(os.Stdout, pkg, filter)
	}
}

func logf(format string, args ...any) {
	if *verbose {
		fmt.Fprintf(os.Stderr, format, args...)
	}
}

// splitPathIdent splits a path.name argument into its components.
// All but the last path element may contain dots.
func splitPathIdent(arg string) (path, name string) {
	if i := strings.LastIndex(arg, "."); i >= 0 {
		if j := strings.LastIndex(arg, "/"); j < i {
			// '.' is not part of path
			path = arg[:i]
			name = arg[i+1:]
			return
		}
	}
	path = arg
	return
}

// tryPrefixes tries to import the package given by (the possibly partial) path using the given importer imp
// by prepending all possible prefixes to path. It returns with the first package that it could import, or
// with an error.
func tryPrefixes(prefixes chan string, path string, imp types.Importer) (pkg *types.Package, err error) {
	for prefix := range prefixes {
		actual := path
		if prefix == "" {
			// don't use filepath.Join as it will sanitize the path and remove
			// a leading dot and then the path is not recognized as a relative
			// package path by the importers anymore
			logf("\ttrying no prefix\n")
		} else {
			actual = filepath.Join(prefix, path)
			logf("\ttrying prefix %q\n", prefix)
		}
		pkg, err = imp.Import(actual)
		if err == nil {
			break
		}
		logf("\t=> importing %q failed: %s\n", actual, err)
	}
	return
}

// tryImporters is an importer that tries all registered importers
// successively until one of them succeeds or all of them failed.
type tryImporters struct{}

func (t *tryImporters) Import(path string) (pkg *types.Package, err error) {
	for i, imp := range importers {
		logf("\t\ttrying %s import\n", sources[i])
		pkg, err = imp.Import(path)
		if err == nil {
			break
		}
		logf("\t\t=> %s import failed: %s\n", sources[i], err)
	}
	return
}

type protector struct {
	imp types.Importer
}

func (p *protector) Import(path string) (pkg *types.Package, err error) {
	defer func() {
		if recover() != nil {
			pkg = nil
			err = errImportFailed
		}
	}()
	return p.imp.Import(path)
}

// protect protects an importer imp from panics and returns the protected importer.
func protect(imp types.Importer) types.Importer {
	return &protector{imp}
}

// register registers an importer imp for a given source src.
func register(src string, imp types.Importer) {
	if lookup(src) != nil {
		panic(src + " importer already registered")
	}
	sources = append(sources, src)
	importers = append(importers, protect(imp))
}

// lookup returns the importer imp for a given source src.
func lookup(src string) types.Importer {
	for i, s := range sources {
		if s == src {
			return importers[i]
		}
	}
	return nil
}

func genPrefixes(out chan string, all bool) {
	out <- ""
	if all {
		platform := build.Default.GOOS + "_" + build.Default.GOARCH
		dirnames := append([]string{build.Default.GOROOT}, filepath.SplitList(build.Default.GOPATH)...)
		for _, dirname := range dirnames {
			walkDir(filepath.Join(dirname, "pkg", platform), "", out)
		}
	}
	close(out)
}

func walkDir(dirname, prefix string, out chan string) {
	fiList, err := os.ReadDir(dirname)
	if err != nil {
		return
	}
	for _, fi := range fiList {
		if fi.IsDir() && !strings.HasPrefix(fi.Name(), ".") {
			prefix := filepath.Join(prefix, fi.Name())
			out <- prefix
			walkDir(filepath.Join(dirname, fi.Name()), prefix, out)
		}
	}
}


================================================
FILE: cmd/godex/isAlias18.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.9

package main

import "go/types"

func isAlias(obj *types.TypeName) bool {
	return false // there are no type aliases before Go 1.9
}


================================================
FILE: cmd/godex/isAlias19.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.9

package main

import "go/types"

func isAlias(obj *types.TypeName) bool {
	return obj.IsAlias()
}


================================================
FILE: cmd/godex/print.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"io"
	"math/big"
)

// TODO(gri) use tabwriter for alignment?

func print(w io.Writer, pkg *types.Package, filter func(types.Object) bool) {
	var p printer
	p.pkg = pkg
	p.printPackage(pkg, filter)
	p.printGccgoExtra(pkg)
	io.Copy(w, &p.buf)
}

type printer struct {
	pkg    *types.Package
	buf    bytes.Buffer
	indent int  // current indentation level
	last   byte // last byte written
}

func (p *printer) print(s string) {
	// Write the string one byte at a time. We care about the presence of
	// newlines for indentation which we will see even in the presence of
	// (non-corrupted) Unicode; no need to read one rune at a time.
	for i := 0; i < len(s); i++ {
		ch := s[i]
		if ch != '\n' && p.last == '\n' {
			// Note: This could lead to a range overflow for very large
			// indentations, but it's extremely unlikely to happen for
			// non-pathological code.
			p.buf.WriteString("\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t"[:p.indent])
		}
		p.buf.WriteByte(ch)
		p.last = ch
	}
}

func (p *printer) printf(format string, args ...any) {
	p.print(fmt.Sprintf(format, args...))
}

// methodsFor returns the named type and corresponding methods if the type
// denoted by obj is not an interface and has methods. Otherwise it returns
// the zero value.
func methodsFor(obj *types.TypeName) (*types.Named, []*types.Selection) {
	named, _ := types.Unalias(obj.Type()).(*types.Named)
	if named == nil {
		// A type name's type can also be the
		// exported basic type unsafe.Pointer.
		return nil, nil
	}
	if _, ok := named.Underlying().(*types.Interface); ok {
		// ignore interfaces
		return nil, nil
	}
	methods := combinedMethodSet(named)
	if len(methods) == 0 {
		return nil, nil
	}
	return named, methods
}

func (p *printer) printPackage(pkg *types.Package, filter func(types.Object) bool) {
	// collect objects by kind
	var (
		consts   []*types.Const
		typem    []*types.Named    // non-interface types with methods
		typez    []*types.TypeName // interfaces or types without methods
		vars     []*types.Var
		funcs    []*types.Func
		builtins []*types.Builtin
		methods  = make(map[*types.Named][]*types.Selection) // method sets for named types
	)
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		if obj.Exported() {
			// collect top-level exported and possibly filtered objects
			if filter == nil || filter(obj) {
				switch obj := obj.(type) {
				case *types.Const:
					consts = append(consts, obj)
				case *types.TypeName:
					// group into types with methods and types without
					if named, m := methodsFor(obj); named != nil {
						typem = append(typem, named)
						methods[named] = m
					} else {
						typez = append(typez, obj)
					}
				case *types.Var:
					vars = append(vars, obj)
				case *types.Func:
					funcs = append(funcs, obj)
				case *types.Builtin:
					// for unsafe.Sizeof, etc.
					builtins = append(builtins, obj)
				}
			}
		} else if filter == nil {
			// no filtering: collect top-level unexported types with methods
			if obj, _ := obj.(*types.TypeName); obj != nil {
				// see case *types.TypeName above
				if named, m := methodsFor(obj); named != nil {
					typem = append(typem, named)
					methods[named] = m
				}
			}
		}
	}

	p.printf("package %s  // %q\n", pkg.Name(), pkg.Path())

	p.printDecl("const", len(consts), func() {
		for _, obj := range consts {
			p.printObj(obj)
			p.print("\n")
		}
	})

	p.printDecl("var", len(vars), func() {
		for _, obj := range vars {
			p.printObj(obj)
			p.print("\n")
		}
	})

	p.printDecl("type", len(typez), func() {
		for _, obj := range typez {
			p.printf("%s ", obj.Name())
			typ := obj.Type()
			if isAlias(obj) {
				p.print("= ")
				p.writeType(p.pkg, typ)
			} else {
				p.writeType(p.pkg, typ.Underlying())
			}
			p.print("\n")
		}
	})

	// non-interface types with methods
	for _, named := range typem {
		first := true
		if obj := named.Obj(); obj.Exported() {
			if first {
				p.print("\n")
				first = false
			}
			p.printf("type %s ", obj.Name())
			p.writeType(p.pkg, named.Underlying())
			p.print("\n")
		}
		for _, m := range methods[named] {
			if obj := m.Obj(); obj.Exported() {
				if first {
					p.print("\n")
					first = false
				}
				p.printFunc(m.Recv(), obj.(*types.Func))
				p.print("\n")
			}
		}
	}

	if len(funcs) > 0 {
		p.print("\n")
		for _, obj := range funcs {
			p.printFunc(nil, obj)
			p.print("\n")
		}
	}

	// TODO(gri) better handling of builtins (package unsafe only)
	if len(builtins) > 0 {
		p.print("\n")
		for _, obj := range builtins {
			p.printf("func %s() // builtin\n", obj.Name())
		}
	}

	p.print("\n")
}

func (p *printer) printDecl(keyword string, n int, printGroup func()) {
	switch n {
	case 0:
		// nothing to do
	case 1:
		p.printf("\n%s ", keyword)
		printGroup()
	default:
		p.printf("\n%s (\n", keyword)
		p.indent++
		printGroup()
		p.indent--
		p.print(")\n")
	}
}

// absInt returns the absolute value of v as a *big.Int.
// v must be a numeric value.
func absInt(v constant.Value) *big.Int {
	// compute big-endian representation of v
	b := constant.Bytes(v) // little-endian
	for i, j := 0, len(b)-1; i < j; i, j = i+1, j-1 {
		b[i], b[j] = b[j], b[i]
	}
	return new(big.Int).SetBytes(b)
}

var (
	one = big.NewRat(1, 1)
	ten = big.NewRat(10, 1)
)

// floatString returns the string representation for a
// numeric value v in normalized floating-point format.
func floatString(v constant.Value) string {
	if constant.Sign(v) == 0 {
		return "0.0"
	}
	// x != 0

	// convert |v| into a big.Rat x
	x := new(big.Rat).SetFrac(absInt(constant.Num(v)), absInt(constant.Denom(v)))

	// normalize x and determine exponent e
	// (This is not very efficient, but also not speed-critical.)
	var e int
	for x.Cmp(ten) >= 0 {
		x.Quo(x, ten)
		e++
	}
	for x.Cmp(one) < 0 {
		x.Mul(x, ten)
		e--
	}

	// TODO(gri) Values such as 1/2 are easier to read in form 0.5
	// rather than 5.0e-1. Similarly, 1.0e1 is easier to read as
	// 10.0. Fine-tune best exponent range for readability.

	s := x.FloatString(100) // good-enough precision

	// trim trailing 0's
	i := len(s)
	for i > 0 && s[i-1] == '0' {
		i--
	}
	s = s[:i]

	// add a 0 if the number ends in decimal point
	if len(s) > 0 && s[len(s)-1] == '.' {
		s += "0"
	}

	// add exponent and sign
	if e != 0 {
		s += fmt.Sprintf("e%+d", e)
	}
	if constant.Sign(v) < 0 {
		s = "-" + s
	}

	// TODO(gri) If v is a "small" fraction (i.e., numerator and denominator
	// are just a small number of decimal digits), add the exact fraction as
	// a comment. For instance: 3.3333...e-1 /* = 1/3 */

	return s
}

// valString returns the string representation for the value v.
// Setting floatFmt forces an integer value to be formatted in
// normalized floating-point format.
// TODO(gri) Move this code into package constant.
func valString(v constant.Value, floatFmt bool) string {
	switch v.Kind() {
	case constant.Int:
		if floatFmt {
			return floatString(v)
		}
	case constant.Float:
		return floatString(v)
	case constant.Complex:
		re := constant.Real(v)
		im := constant.Imag(v)
		var s string
		if constant.Sign(re) != 0 {
			s = floatString(re)
			if constant.Sign(im) >= 0 {
				s += " + "
			} else {
				s += " - "
				im = constant.UnaryOp(token.SUB, im, 0) // negate im
			}
		}
		// im != 0, otherwise v would be constant.Int or constant.Float
		return s + floatString(im) + "i"
	}
	return v.String()
}

func (p *printer) printObj(obj types.Object) {
	p.print(obj.Name())

	typ, basic := obj.Type().Underlying().(*types.Basic)
	if basic && typ.Info()&types.IsUntyped != 0 {
		// don't write untyped types
	} else {
		p.print(" ")
		p.writeType(p.pkg, obj.Type())
	}

	if obj, ok := obj.(*types.Const); ok {
		floatFmt := basic && typ.Info()&(types.IsFloat|types.IsComplex) != 0
		p.print(" = ")
		p.print(valString(obj.Val(), floatFmt))
	}
}

func (p *printer) printFunc(recvType types.Type, obj *types.Func) {
	p.print("func ")
	sig := obj.Type().(*types.Signature)
	if recvType != nil {
		p.print("(")
		p.writeType(p.pkg, recvType)
		p.print(") ")
	}
	p.print(obj.Name())
	p.writeSignature(p.pkg, sig)
}

// combinedMethodSet returns the method set for a named type T
// merged with all the methods of *T that have different names than
// the methods of T.
//
// combinedMethodSet is analogous to types/typeutil.IntuitiveMethodSet
// but doesn't require a MethodSetCache.
// TODO(gri) If this functionality doesn't change over time, consider
// just calling IntuitiveMethodSet eventually.
func combinedMethodSet(T *types.Named) []*types.Selection {
	// method set for T
	mset := types.NewMethodSet(T)
	var res []*types.Selection
	for i, n := 0, mset.Len(); i < n; i++ {
		res = append(res, mset.At(i))
	}

	// add all *T methods with names different from T methods
	pmset := types.NewMethodSet(types.NewPointer(T))
	for i, n := 0, pmset.Len(); i < n; i++ {
		pm := pmset.At(i)
		if obj := pm.Obj(); mset.Lookup(obj.Pkg(), obj.Name()) == nil {
			res = append(res, pm)
		}
	}

	return res
}


================================================
FILE: cmd/godex/source.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements access to export data from source.

package main

import "go/types"

func init() {
	register("source", sourceImporter{})
}

type sourceImporter struct{}

func (sourceImporter) Import(path string) (*types.Package, error) {
	panic("unimplemented")
}


================================================
FILE: cmd/godex/writetype.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements writing of types. The functionality is lifted
// directly from go/types, but now contains various modifications for
// nicer output.
//
// TODO(gri) back-port once we have a fixed interface and once the
// go/types API is not frozen anymore for the 1.3 release; and remove
// this implementation if possible.

package main

import (
	"go/types"
	"slices"
)

func (p *printer) writeType(this *types.Package, typ types.Type) {
	p.writeTypeInternal(this, typ, make([]types.Type, 8))
}

// From go/types - leave for now to ease back-porting this code.
const GcCompatibilityMode = false

func (p *printer) writeTypeInternal(this *types.Package, typ types.Type, visited []types.Type) {
	// Theoretically, this is a quadratic lookup algorithm, but in
	// practice deeply nested composite types with unnamed component
	// types are uncommon. This code is likely more efficient than
	// using a map.
	if slices.Contains(visited, typ) {
		p.printf("○%T", typ) // cycle to typ
		return
	}
	visited = append(visited, typ)

	switch t := typ.(type) {
	case nil:
		p.print("<nil>")

	case *types.Basic:
		if t.Kind() == types.UnsafePointer {
			p.print("unsafe.")
		}
		if GcCompatibilityMode {
			// forget the alias names
			switch t.Kind() {
			case types.Byte:
				t = types.Typ[types.Uint8]
			case types.Rune:
				t = types.Typ[types.Int32]
			}
		}
		p.print(t.Name())

	case *types.Array:
		p.printf("[%d]", t.Len())
		p.writeTypeInternal(this, t.Elem(), visited)

	case *types.Slice:
		p.print("[]")
		p.writeTypeInternal(this, t.Elem(), visited)

	case *types.Struct:
		n := t.NumFields()
		if n == 0 {
			p.print("struct{}")
			return
		}

		p.print("struct {\n")
		p.indent++
		for i := range n {
			f := t.Field(i)
			if !f.Anonymous() {
				p.printf("%s ", f.Name())
			}
			p.writeTypeInternal(this, f.Type(), visited)
			if tag := t.Tag(i); tag != "" {
				p.printf(" %q", tag)
			}
			p.print("\n")
		}
		p.indent--
		p.print("}")

	case *types.Pointer:
		p.print("*")
		p.writeTypeInternal(this, t.Elem(), visited)

	case *types.Tuple:
		p.writeTuple(this, t, false, visited)

	case *types.Signature:
		p.print("func")
		p.writeSignatureInternal(this, t, visited)

	case *types.Interface:
		// We write the source-level methods and embedded types rather
		// than the actual method set since resolved method signatures
		// may have non-printable cycles if parameters have anonymous
		// interface types that (directly or indirectly) embed the
		// current interface. For instance, consider the result type
		// of m:
		//
		//     type T interface{
		//         m() interface{ T }
		//     }
		//
		n := t.NumMethods()
		if n == 0 {
			p.print("any")
			return
		}

		p.print("interface {\n")
		p.indent++
		if GcCompatibilityMode {
			// print flattened interface
			// (useful to compare against gc-generated interfaces)
			for i := range n {
				m := t.Method(i)
				p.print(m.Name())
				p.writeSignatureInternal(this, m.Type().(*types.Signature), visited)
				p.print("\n")
			}
		} else {
			// print explicit interface methods and embedded types
			for i, n := 0, t.NumExplicitMethods(); i < n; i++ {
				m := t.ExplicitMethod(i)
				p.print(m.Name())
				p.writeSignatureInternal(this, m.Type().(*types.Signature), visited)
				p.print("\n")
			}
			for i, n := 0, t.NumEmbeddeds(); i < n; i++ {
				typ := t.EmbeddedType(i)
				p.writeTypeInternal(this, typ, visited)
				p.print("\n")
			}
		}
		p.indent--
		p.print("}")

	case *types.Map:
		p.print("map[")
		p.writeTypeInternal(this, t.Key(), visited)
		p.print("]")
		p.writeTypeInternal(this, t.Elem(), visited)

	case *types.Chan:
		var s string
		var parens bool
		switch t.Dir() {
		case types.SendRecv:
			s = "chan "
			// chan (<-chan T) requires parentheses
			if c, _ := t.Elem().(*types.Chan); c != nil && c.Dir() == types.RecvOnly {
				parens = true
			}
		case types.SendOnly:
			s = "chan<- "
		case types.RecvOnly:
			s = "<-chan "
		default:
			panic("unreachable")
		}
		p.print(s)
		if parens {
			p.print("(")
		}
		p.writeTypeInternal(this, t.Elem(), visited)
		if parens {
			p.print(")")
		}

	case *types.Alias:
		// TODO(adonovan): display something aliasy.
		p.writeTypeInternal(this, types.Unalias(t), visited)

	case *types.Named:
		s := "<Named w/o object>"
		if obj := t.Obj(); obj != nil {
			if pkg := obj.Pkg(); pkg != nil {
				if pkg != this {
					p.print(pkg.Path())
					p.print(".")
				}
				// TODO(gri): function-local named types should be displayed
				// differently from named types at package level to avoid
				// ambiguity.
			}
			s = obj.Name()
		}
		p.print(s)

	default:
		// For externally defined implementations of Type.
		p.print(t.String())
	}
}

func (p *printer) writeTuple(this *types.Package, tup *types.Tuple, variadic bool, visited []types.Type) {
	p.print("(")
	for i, n := 0, tup.Len(); i < n; i++ {
		if i > 0 {
			p.print(", ")
		}
		v := tup.At(i)
		if name := v.Name(); name != "" {
			p.print(name)
			p.print(" ")
		}
		typ := v.Type()
		if variadic && i == n-1 {
			p.print("...")
			typ = typ.(*types.Slice).Elem()
		}
		p.writeTypeInternal(this, typ, visited)
	}
	p.print(")")
}

func (p *printer) writeSignature(this *types.Package, sig *types.Signature) {
	p.writeSignatureInternal(this, sig, make([]types.Type, 8))
}

func (p *printer) writeSignatureInternal(this *types.Package, sig *types.Signature, visited []types.Type) {
	p.writeTuple(this, sig.Params(), sig.Variadic(), visited)

	res := sig.Results()
	n := res.Len()
	if n == 0 {
		// no result
		return
	}

	p.print(" ")
	if n == 1 && res.At(0).Name() == "" {
		// single unnamed result
		p.writeTypeInternal(this, res.At(0).Type(), visited)
		return
	}

	// multiple or named result(s)
	p.writeTuple(this, res, false, visited)
}


================================================
FILE: cmd/goimports/doc.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Command goimports updates your Go import lines,
adding missing ones and removing unreferenced ones.

	$ go install golang.org/x/tools/cmd/goimports@latest

In addition to fixing imports, goimports also formats
your code in the same style as gofmt so it can be used
as a replacement for your editor's gofmt-on-save hook.

For emacs, make sure you have the latest go-mode.el:

	https://github.com/dominikh/go-mode.el

Then in your .emacs file:

	(setq gofmt-command "goimports")
	(add-hook 'before-save-hook 'gofmt-before-save)

For vim, set "gofmt_command" to "goimports":

	https://golang.org/change/39c724dd7f252
	https://golang.org/wiki/IDEsAndTextEditorPlugins
	etc

For GoSublime, follow the steps described here:

	http://michaelwhatcott.com/gosublime-goimports/

For other editors, you probably know what to do.

To exclude directories in your $GOPATH from being scanned for Go
files, goimports respects a configuration file at
$GOPATH/src/.goimportsignore which may contain blank lines, comment
lines (beginning with '#'), or lines naming a directory relative to
the configuration file to ignore when scanning. No globbing or regex
patterns are allowed. Use the "-v" verbose flag to verify it's
working and see what goimports is doing.

File bugs or feature requests at:

	https://golang.org/issues/new?title=x/tools/cmd/goimports:+

Happy hacking!
*/
package main // import "golang.org/x/tools/cmd/goimports"


================================================
FILE: cmd/goimports/goimports.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bufio"
	"bytes"
	"errors"
	"flag"
	"fmt"
	"go/scanner"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"runtime/pprof"
	"strings"

	"golang.org/x/telemetry/counter"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/imports"
)

var (
	// main operation modes
	list   = flag.Bool("l", false, "list files whose formatting differs from goimport's")
	write  = flag.Bool("w", false, "write result to (source) file instead of stdout")
	doDiff = flag.Bool("d", false, "display diffs instead of rewriting files")
	srcdir = flag.String("srcdir", "", "choose imports as if source code is from `dir`. When operating on a single file, dir may instead be the complete file name.")

	verbose bool // verbose logging

	cpuProfile     = flag.String("cpuprofile", "", "CPU profile output")
	memProfile     = flag.String("memprofile", "", "memory profile output")
	memProfileRate = flag.Int("memrate", 0, "if > 0, sets runtime.MemProfileRate")

	options = &imports.Options{
		TabWidth:  8,
		TabIndent: true,
		Comments:  true,
		Fragment:  true,
		Env: &imports.ProcessEnv{
			GocmdRunner: &gocommand.Runner{},
		},
	}
	exitCode = 0
)

func init() {
	flag.BoolVar(&options.AllErrors, "e", false, "report all errors (not just the first 10 on different lines)")
	flag.StringVar(&options.LocalPrefix, "local", "", "put imports beginning with this string after 3rd-party packages; comma-separated list")
	flag.BoolVar(&options.FormatOnly, "format-only", false, "if true, don't fix imports and only format. In this mode, goimports is effectively gofmt, with the addition that imports are grouped into sections.")
}

func report(err error) {
	scanner.PrintError(os.Stderr, err)
	exitCode = 2
}

func usage() {
	fmt.Fprintf(os.Stderr, "usage: goimports [flags] [path ...]\n")
	flag.PrintDefaults()
	os.Exit(2)
}

func isGoFile(f os.FileInfo) bool {
	// ignore non-Go files
	name := f.Name()
	return !f.IsDir() && !strings.HasPrefix(name, ".") && strings.HasSuffix(name, ".go")
}

// argumentType is which mode goimports was invoked as.
type argumentType int

const (
	// fromStdin means the user is piping their source into goimports.
	fromStdin argumentType = iota

	// singleArg is the common case from editors, when goimports is run on
	// a single file.
	singleArg

	// multipleArg is when the user ran "goimports file1.go file2.go"
	// or ran goimports on a directory tree.
	multipleArg
)

func processFile(filename string, in io.Reader, out io.Writer, argType argumentType) error {
	opt := options
	if argType == fromStdin {
		nopt := *options
		nopt.Fragment = true
		opt = &nopt
	}

	if in == nil {
		f, err := os.Open(filename)
		if err != nil {
			return err
		}
		defer f.Close()
		in = f
	}

	src, err := io.ReadAll(in)
	if err != nil {
		return err
	}

	target := filename
	if *srcdir != "" {
		// Determine whether the provided -srcdirc is a directory or file
		// and then use it to override the target.
		//
		// See https://github.com/dominikh/go-mode.el/issues/146
		if isFile(*srcdir) {
			if argType == multipleArg {
				return errors.New("-srcdir value can't be a file when passing multiple arguments or when walking directories")
			}
			target = *srcdir
		} else if argType == singleArg && strings.HasSuffix(*srcdir, ".go") && !isDir(*srcdir) {
			// For a file which doesn't exist on disk yet, but might shortly.
			// e.g. user in editor opens $DIR/newfile.go and newfile.go doesn't yet exist on disk.
			// The goimports on-save hook writes the buffer to a temp file
			// first and runs goimports before the actual save to newfile.go.
			// The editor's buffer is named "newfile.go" so that is passed to goimports as:
			//      goimports -srcdir=/gopath/src/pkg/newfile.go /tmp/gofmtXXXXXXXX.go
			// and then the editor reloads the result from the tmp file and writes
			// it to newfile.go.
			target = *srcdir
		} else {
			// Pretend that file is from *srcdir in order to decide
			// visible imports correctly.
			target = filepath.Join(*srcdir, filepath.Base(filename))
		}
	}

	res, err := imports.Process(target, src, opt)
	if err != nil {
		return err
	}

	if !bytes.Equal(src, res) {
		// formatting has changed
		if *list {
			fmt.Fprintln(out, filename)
		}
		if *write {
			if argType == fromStdin {
				// filename is "<standard input>"
				return errors.New("can't use -w on stdin")
			}
			// On Windows, we need to re-set the permissions from the file. See golang/go#38225.
			var perms os.FileMode
			if fi, err := os.Stat(filename); err == nil {
				perms = fi.Mode() & os.ModePerm
			}
			err = os.WriteFile(filename, res, perms)
			if err != nil {
				return err
			}
		}
		if *doDiff {
			if argType == fromStdin {
				filename = "stdin.go" // because <standard input>.orig looks silly
			}
			data, err := diff(src, res, filename)
			if err != nil {
				return fmt.Errorf("computing diff: %s", err)
			}
			fmt.Printf("diff -u %s %s\n", filepath.ToSlash(filename+".orig"), filepath.ToSlash(filename))
			out.Write(data)
		}
	}

	if !*list && !*write && !*doDiff {
		_, err = out.Write(res)
	}

	return err
}

func visitFile(path string, f os.FileInfo, err error) error {
	if err == nil && isGoFile(f) {
		err = processFile(path, nil, os.Stdout, multipleArg)
	}
	if err != nil {
		report(err)
	}
	return nil
}

func walkDir(path string) {
	filepath.Walk(path, visitFile)
}

func main() {
	// is anyone using this command?
	counter.Open()
	counter.Inc("tools/cmd:goimports")
	runtime.GOMAXPROCS(runtime.NumCPU())

	// call gofmtMain in a separate function
	// so that it can use defer and have them
	// run before the exit.
	gofmtMain()
	os.Exit(exitCode)
}

// parseFlags parses command line flags and returns the paths to process.
// It's a var so that custom implementations can replace it in other files.
var parseFlags = func() []string {
	flag.BoolVar(&verbose, "v", false, "verbose logging")

	flag.Parse()
	return flag.Args()
}

func bufferedFileWriter(dest string) (w io.Writer, close func()) {
	f, err := os.Create(dest)
	if err != nil {
		log.Fatal(err)
	}
	bw := bufio.NewWriter(f)
	return bw, func() {
		if err := bw.Flush(); err != nil {
			log.Fatalf("error flushing %v: %v", dest, err)
		}
		if err := f.Close(); err != nil {
			log.Fatal(err)
		}
	}
}

func gofmtMain() {
	flag.Usage = usage
	paths := parseFlags()

	if *cpuProfile != "" {
		bw, flush := bufferedFileWriter(*cpuProfile)
		pprof.StartCPUProfile(bw)
		defer flush()
		defer pprof.StopCPUProfile()
	}
	// doTrace is a conditionally compiled wrapper around runtime/trace. It is
	// used to allow goimports to compile under gccgo, which does not support
	// runtime/trace. See https://golang.org/issue/15544.
	defer doTrace()()
	if *memProfileRate > 0 {
		runtime.MemProfileRate = *memProfileRate
		bw, flush := bufferedFileWriter(*memProfile)
		defer func() {
			runtime.GC() // materialize all statistics
			if err := pprof.WriteHeapProfile(bw); err != nil {
				log.Fatal(err)
			}
			flush()
		}()
	}

	if verbose {
		log.SetFlags(log.LstdFlags | log.Lmicroseconds)
		options.Env.Logf = log.Printf
	}
	if options.TabWidth < 0 {
		fmt.Fprintf(os.Stderr, "negative tabwidth %d\n", options.TabWidth)
		exitCode = 2
		return
	}

	if len(paths) == 0 {
		if err := processFile("<standard input>", os.Stdin, os.Stdout, fromStdin); err != nil {
			report(err)
		}
		return
	}

	argType := singleArg
	if len(paths) > 1 {
		argType = multipleArg
	}

	for _, path := range paths {
		switch dir, err := os.Stat(path); {
		case err != nil:
			report(err)
		case dir.IsDir():
			walkDir(path)
		default:
			if err := processFile(path, nil, os.Stdout, argType); err != nil {
				report(err)
			}
		}
	}
}

func writeTempFile(dir, prefix string, data []byte) (string, error) {
	file, err := os.CreateTemp(dir, prefix)
	if err != nil {
		return "", err
	}
	_, err = file.Write(data)
	if err1 := file.Close(); err == nil {
		err = err1
	}
	if err != nil {
		os.Remove(file.Name())
		return "", err
	}
	return file.Name(), nil
}

func diff(b1, b2 []byte, filename string) (data []byte, err error) {
	f1, err := writeTempFile("", "gofmt", b1)
	if err != nil {
		return
	}
	defer os.Remove(f1)

	f2, err := writeTempFile("", "gofmt", b2)
	if err != nil {
		return
	}
	defer os.Remove(f2)

	cmd := "diff"
	if runtime.GOOS == "plan9" {
		cmd = "/bin/ape/diff"
	}

	data, err = exec.Command(cmd, "-u", f1, f2).CombinedOutput()
	if len(data) > 0 {
		// diff exits with a non-zero status when the files don't match.
		// Ignore that failure as long as we get output.
		return replaceTempFilename(data, filename)
	}
	return
}

// replaceTempFilename replaces temporary filenames in diff with actual one.
//
// --- /tmp/gofmt316145376	2017-02-03 19:13:00.280468375 -0500
// +++ /tmp/gofmt617882815	2017-02-03 19:13:00.280468375 -0500
// ...
// ->
// --- path/to/file.go.orig	2017-02-03 19:13:00.280468375 -0500
// +++ path/to/file.go	2017-02-03 19:13:00.280468375 -0500
// ...
func replaceTempFilename(diff []byte, filename string) ([]byte, error) {
	bs := bytes.SplitN(diff, []byte{'\n'}, 3)
	if len(bs) < 3 {
		return nil, fmt.Errorf("got unexpected diff for %s", filename)
	}
	// Preserve timestamps.
	var t0, t1 []byte
	if i := bytes.LastIndexByte(bs[0], '\t'); i != -1 {
		t0 = bs[0][i:]
	}
	if i := bytes.LastIndexByte(bs[1], '\t'); i != -1 {
		t1 = bs[1][i:]
	}
	// Always print filepath with slash separator.
	f := filepath.ToSlash(filename)
	bs[0] = fmt.Appendf(nil, "--- %s%s", f+".orig", t0)
	bs[1] = fmt.Appendf(nil, "+++ %s%s", f, t1)
	return bytes.Join(bs, []byte{'\n'}), nil
}

// isFile reports whether name is a file.
func isFile(name string) bool {
	fi, err := os.Stat(name)
	return err == nil && fi.Mode().IsRegular()
}

// isDir reports whether name is a directory.
func isDir(name string) bool {
	fi, err := os.Stat(name)
	return err == nil && fi.IsDir()
}


================================================
FILE: cmd/goimports/goimports_gc.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build gc

package main

import (
	"flag"
	"runtime/trace"
)

var traceProfile = flag.String("trace", "", "trace profile output")

func doTrace() func() {
	if *traceProfile != "" {
		bw, flush := bufferedFileWriter(*traceProfile)
		trace.Start(bw)
		return func() {
			trace.Stop()
			flush()
		}
	}
	return func() {}
}


================================================
FILE: cmd/goimports/goimports_not_gc.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !gc

package main

func doTrace() func() {
	return func() {}
}


================================================
FILE: cmd/gomvpkg/main.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The gomvpkg command moves go packages, updating import declarations.
// See the -help message or Usage constant for details.
package main

import (
	"flag"
	"fmt"
	"go/build"
	"os"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/refactor/rename"
)

var (
	fromFlag     = flag.String("from", "", "Import path of package to be moved")
	toFlag       = flag.String("to", "", "Destination import path for package")
	vcsMvCmdFlag = flag.String("vcs_mv_cmd", "", `A template for the version control system's "move directory" command, e.g. "git mv {{.Src}} {{.Dst}}"`)
	helpFlag     = flag.Bool("help", false, "show usage message")
)

func init() {
	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
}

const Usage = `gomvpkg: moves a package, updating import declarations

Usage:

 gomvpkg -from <path> -to <path> [-vcs_mv_cmd <template>]

Flags:

-from        specifies the import path of the package to be moved

-to          specifies the destination import path

-vcs_mv_cmd  specifies a shell command to inform the version control system of a
             directory move.  The argument is a template using the syntax of the
             text/template package. It has two fields: Src and Dst, the absolute
             paths of the directories.

             For example: "git mv {{.Src}} {{.Dst}}"

gomvpkg determines the set of packages that might be affected, including all
packages importing the 'from' package and any of its subpackages. It will move
the 'from' package and all its subpackages to the destination path and update all
imports of those packages to point to its new import path.

gomvpkg rejects moves in which a package already exists at the destination import
path, or in which a directory already exists at the location the package would be
moved to.

gomvpkg will not always be able to rename imports when a package's name is changed.
Import statements may want further cleanup.

gomvpkg's behavior is not defined if any of the packages to be moved are
imported using dot imports.

Examples:

% gomvpkg -from myproject/foo -to myproject/bar

  Move the package with import path "myproject/foo" to the new path
  "myproject/bar".

% gomvpkg -from myproject/foo -to myproject/bar -vcs_mv_cmd "git mv {{.Src}} {{.Dst}}"

  Move the package with import path "myproject/foo" to the new path
  "myproject/bar" using "git mv" to execute the directory move.
`

func main() {
	flag.Parse()

	if len(flag.Args()) > 0 {
		fmt.Fprintln(os.Stderr, "gomvpkg: surplus arguments.")
		os.Exit(1)
	}

	if *helpFlag || *fromFlag == "" || *toFlag == "" {
		fmt.Print(Usage)
		return
	}

	if err := rename.Move(&build.Default, *fromFlag, *toFlag, *vcsMvCmdFlag); err != nil {
		fmt.Fprintf(os.Stderr, "gomvpkg: %s.\n", err)
		os.Exit(1)
	}
}


================================================
FILE: cmd/gonew/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Gonew starts a new Go module by copying a template module.
//
// Usage:
//
//	gonew srcmod[@version] [dstmod [dir]]
//
// Gonew makes a copy of the srcmod module, changing its module path to dstmod.
// It writes that new module to a new directory named by dir.
// If dir already exists, it must be an empty directory.
// If dir is omitted, gonew uses ./elem where elem is the final path element of dstmod.
//
// This command is highly experimental and subject to change.
//
// # Example
//
// To install gonew:
//
//	go install golang.org/x/tools/cmd/gonew@latest
//
// To clone the basic command-line program template golang.org/x/example/hello
// as your.domain/myprog, in the directory ./myprog:
//
//	gonew golang.org/x/example/hello your.domain/myprog
//
// To clone the latest copy of the rsc.io/quote module, keeping that module path,
// into ./quote:
//
//	gonew rsc.io/quote
package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/parser"
	"go/token"
	"io/fs"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"strconv"
	"strings"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
	"golang.org/x/tools/internal/edit"
)

func usage() {
	fmt.Fprintf(os.Stderr, "usage: gonew srcmod[@version] [dstmod [dir]]\n")
	fmt.Fprintf(os.Stderr, "See https://pkg.go.dev/golang.org/x/tools/cmd/gonew.\n")
	os.Exit(2)
}

func main() {
	log.SetPrefix("gonew: ")
	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()
	args := flag.Args()

	if len(args) < 1 || len(args) > 3 {
		usage()
	}

	srcMod := args[0]
	srcModVers := srcMod
	if !strings.Contains(srcModVers, "@") {
		srcModVers += "@latest"
	}
	srcMod, _, _ = strings.Cut(srcMod, "@")
	if err := module.CheckPath(srcMod); err != nil {
		log.Fatalf("invalid source module name: %v", err)
	}

	dstMod := srcMod
	if len(args) >= 2 {
		dstMod = args[1]
		if err := module.CheckPath(dstMod); err != nil {
			log.Fatalf("invalid destination module name: %v", err)
		}
	}

	var dir string
	if len(args) == 3 {
		dir = args[2]
	} else {
		dir = "." + string(filepath.Separator) + path.Base(dstMod)
	}

	// Dir must not exist or must be an empty directory.
	de, err := os.ReadDir(dir)
	if err == nil && len(de) > 0 {
		log.Fatalf("target directory %s exists and is non-empty", dir)
	}
	needMkdir := err != nil

	var stdout, stderr bytes.Buffer
	cmd := exec.Command("go", "mod", "download", "-json", srcModVers)
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		log.Fatalf("go mod download -json %s: %v\n%s%s", srcModVers, err, stderr.Bytes(), stdout.Bytes())
	}

	var info struct {
		Dir string
	}
	if err := json.Unmarshal(stdout.Bytes(), &info); err != nil {
		log.Fatalf("go mod download -json %s: invalid JSON output: %v\n%s%s", srcMod, err, stderr.Bytes(), stdout.Bytes())
	}

	if needMkdir {
		if err := os.MkdirAll(dir, 0777); err != nil {
			log.Fatal(err)
		}
	}

	// Copy from module cache into new directory, making edits as needed.
	filepath.WalkDir(info.Dir, func(src string, d fs.DirEntry, err error) error {
		if err != nil {
			log.Fatal(err)
		}
		rel, err := filepath.Rel(info.Dir, src)
		if err != nil {
			log.Fatal(err)
		}
		dst := filepath.Join(dir, rel)
		if d.IsDir() {
			if err := os.MkdirAll(dst, 0777); err != nil {
				log.Fatal(err)
			}
			return nil
		}

		data, err := os.ReadFile(src)
		if err != nil {
			log.Fatal(err)
		}

		isRoot := !strings.Contains(rel, string(filepath.Separator))
		if strings.HasSuffix(rel, ".go") {
			data = fixGo(data, rel, srcMod, dstMod, isRoot)
		}
		if rel == "go.mod" {
			data = fixGoMod(data, dstMod)
		}

		if err := os.WriteFile(dst, data, 0666); err != nil {
			log.Fatal(err)
		}
		return nil
	})

	log.Printf("initialized %s in %s", dstMod, dir)
}

// fixGo rewrites the Go source in data to replace srcMod with dstMod.
// isRoot indicates whether the file is in the root directory of the module,
// in which case we also update the package name.
func fixGo(data []byte, file string, srcMod, dstMod string, isRoot bool) []byte {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, file, data, parser.ImportsOnly)
	if err != nil {
		log.Fatalf("parsing source module:\n%s", err)
	}

	buf := edit.NewBuffer(data)
	at := func(p token.Pos) int {
		return fset.File(p).Offset(p)
	}

	srcName := path.Base(srcMod)
	dstName := path.Base(dstMod)
	if isRoot {
		if name := f.Name.Name; name == srcName || name == srcName+"_test" {
			dname := dstName + strings.TrimPrefix(name, srcName)
			if !token.IsIdentifier(dname) {
				log.Fatalf("%s: cannot rename package %s to package %s: invalid package name", file, name, dname)
			}
			buf.Replace(at(f.Name.Pos()), at(f.Name.End()), dname)
		}
	}

	for _, spec := range f.Imports {
		path, err := strconv.Unquote(spec.Path.Value)
		if err != nil {
			continue
		}
		if path == srcMod {
			if srcName != dstName && spec.Name == nil {
				// Add package rename because source code uses original name.
				// The renaming looks strange, but template authors are unlikely to
				// create a template where the root package is imported by packages
				// in subdirectories, and the renaming at least keeps the code working.
				// A more sophisticated approach would be to rename the uses of
				// the package identifier in the file too, but then you have to worry about
				// name collisions, and given how unlikely this is, it doesn't seem worth
				// trying to clean up the file that way.
				buf.Insert(at(spec.Path.Pos()), srcName+" ")
			}
			// Change import path to dstMod
			buf.Replace(at(spec.Path.Pos()), at(spec.Path.End()), strconv.Quote(dstMod))
		}
		if strings.HasPrefix(path, srcMod+"/") {
			// Change import path to begin with dstMod
			buf.Replace(at(spec.Path.Pos()), at(spec.Path.End()), strconv.Quote(strings.Replace(path, srcMod, dstMod, 1)))
		}
	}
	return buf.Bytes()
}

// fixGoMod rewrites the go.mod content in data to add a module
// statement for dstMod.
func fixGoMod(data []byte, dstMod string) []byte {
	f, err := modfile.ParseLax("go.mod", data, nil)
	if err != nil {
		log.Fatalf("parsing source module:\n%s", err)
	}
	f.AddModuleStmt(dstMod)
	new, err := f.Format()
	if err != nil {
		return data
	}
	return new
}


================================================
FILE: cmd/gonew/main_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"archive/zip"
	"bytes"
	"fmt"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/internal/diffp"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

func init() {
	if os.Getenv("TestGonewMain") == "1" {
		main()
		os.Exit(0)
	}
}

func Test(t *testing.T) {
	if !testenv.HasExec() {
		t.Skipf("skipping test: exec not supported on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}

	// Each file in testdata is a txtar file with the command to run,
	// the contents of modules to initialize in a fake proxy,
	// the expected stdout and stderr, and the expected file contents.
	files, err := filepath.Glob("testdata/*.txt")
	if err != nil {
		t.Fatal(err)
	}
	if len(files) == 0 {
		t.Fatal("no test cases")
	}

	for _, file := range files {
		t.Run(filepath.Base(file), func(t *testing.T) {
			data, err := os.ReadFile(file)
			if err != nil {
				t.Fatal(err)
			}
			ar := txtar.Parse(data)

			// If the command begins with ! it means it should fail.
			// After the optional ! the first argument must be 'gonew'
			// followed by the arguments to gonew.
			args := strings.Fields(string(ar.Comment))
			wantFail := false
			if len(args) > 0 && args[0] == "!" {
				wantFail = true
				args = args[1:]
			}
			if len(args) == 0 || args[0] != "gonew" {
				t.Fatalf("invalid command comment")
			}

			// Collect modules into proxy tree and store in temp directory.
			dir := t.TempDir()
			proxyDir := filepath.Join(dir, "proxy")
			writeProxyFiles(t, proxyDir, ar)
			extra := ""
			if runtime.GOOS == "windows" {
				// Windows absolute paths don't start with / so we need one more.
				extra = "/"
			}
			proxyURL := "file://" + extra + filepath.ToSlash(proxyDir)

			// Run gonew in a fresh 'out' directory.
			out := filepath.Join(dir, "out")
			if err := os.Mkdir(out, 0777); err != nil {
				t.Fatal(err)
			}
			cmd := exec.Command(exe, args[1:]...)
			cmd.Dir = out
			cmd.Env = append(os.Environ(), "TestGonewMain=1", "GOPROXY="+proxyURL, "GOSUMDB=off")
			var stdout bytes.Buffer
			var stderr bytes.Buffer
			cmd.Stdout = &stdout
			cmd.Stderr = &stderr
			if err := cmd.Run(); err == nil && wantFail {
				t.Errorf("unexpected success exit")
			} else if err != nil && !wantFail {
				t.Errorf("unexpected failure exit")
			}

			// Collect the expected output from the txtar.
			want := make(map[string]txtar.File)
			for _, f := range ar.Files {
				if f.Name == "stdout" || f.Name == "stderr" || strings.HasPrefix(f.Name, "out/") {
					want[f.Name] = f
				}
			}

			// Check stdout and stderr.
			// Change \ to / so Windows output looks like Unix output.
			stdoutBuf := bytes.ReplaceAll(stdout.Bytes(), []byte(`\`), []byte("/"))
			stderrBuf := bytes.ReplaceAll(stderr.Bytes(), []byte(`\`), []byte("/"))
			// Note that stdout and stderr can be omitted from the archive if empty.
			if !bytes.Equal(stdoutBuf, want["stdout"].Data) {
				t.Errorf("wrong stdout: %s", diffp.Diff("want", want["stdout"].Data, "have", stdoutBuf))
			}
			if !bytes.Equal(stderrBuf, want["stderr"].Data) {
				t.Errorf("wrong stderr: %s", diffp.Diff("want", want["stderr"].Data, "have", stderrBuf))
			}
			delete(want, "stdout")
			delete(want, "stderr")

			// Check remaining expected outputs.
			err = filepath.WalkDir(out, func(name string, info fs.DirEntry, err error) error {
				if err != nil {
					return err
				}
				if info.IsDir() {
					return nil
				}
				data, err := os.ReadFile(name)
				if err != nil {
					return err
				}
				short := "out" + filepath.ToSlash(strings.TrimPrefix(name, out))
				f, ok := want[short]
				if !ok {
					t.Errorf("unexpected file %s:\n%s", short, data)
					return nil
				}
				delete(want, short)
				if !bytes.Equal(data, f.Data) {
					t.Errorf("wrong %s: %s", short, diffp.Diff("want", f.Data, "have", data))
				}
				return nil
			})
			if err != nil {
				t.Fatal(err)
			}
			for name := range want {
				t.Errorf("missing file %s", name)
			}
		})
	}
}

// A Zip is a zip file being written.
type Zip struct {
	buf bytes.Buffer
	w   *zip.Writer
}

// writeProxyFiles collects all the module content from ar and writes
// files in the format of the proxy URL space, so that the 'proxy' directory
// can be used in a GOPROXY=file:/// URL.
func writeProxyFiles(t *testing.T, proxy string, ar *txtar.Archive) {
	zips := make(map[string]*Zip)
	others := make(map[string]string)
	for _, f := range ar.Files {
		i := strings.Index(f.Name, "@")
		if i < 0 {
			continue
		}
		j := strings.Index(f.Name[i:], "/")
		if j < 0 {
			t.Fatalf("unexpected archive file %s", f.Name)
		}
		j += i
		mod, vers, file := f.Name[:i], f.Name[i+1:j], f.Name[j+1:]
		zipName := mod + "/@v/" + vers + ".zip"
		z := zips[zipName]
		if z == nil {
			others[mod+"/@v/list"] += vers + "\n"
			others[mod+"/@v/"+vers+".info"] = fmt.Sprintf("{%q: %q}\n", "Version", vers)
			z = new(Zip)
			z.w = zip.NewWriter(&z.buf)
			zips[zipName] = z
		}
		if file == "go.mod" {
			others[mod+"/@v/"+vers+".mod"] = string(f.Data)
		}
		w, err := z.w.Create(f.Name)
		if err != nil {
			t.Fatal(err)
		}
		if _, err := w.Write(f.Data); err != nil {
			t.Fatal(err)
		}
	}

	for name, z := range zips {
		if err := z.w.Close(); err != nil {
			t.Fatal(err)
		}
		if err := os.MkdirAll(filepath.Dir(filepath.Join(proxy, name)), 0777); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filepath.Join(proxy, name), z.buf.Bytes(), 0666); err != nil {
			t.Fatal(err)
		}
	}
	for name, data := range others {
		// zip loop already created directory
		if err := os.WriteFile(filepath.Join(proxy, name), []byte(data), 0666); err != nil {
			t.Fatal(err)
		}
	}
}


================================================
FILE: cmd/gonew/testdata/quote.txt
================================================
gonew example.com/quote my.com/test

-- example.com/quote@v1.5.2/go.mod --
module example.com/quote
-- example.com/quote@v1.5.2/quote.go --
package quote

import (
	"example.com/quote/bar"
)

func Quote() {}
-- example.com/quote@v1.5.2/quote/another.go --
package quote // another package quote!
-- stderr --
gonew: initialized my.com/test in ./test
-- out/test/go.mod --
module my.com/test
-- out/test/quote.go --
package test

import (
	"my.com/test/bar"
)

func Quote() {}
-- out/test/quote/another.go --
package quote // another package quote!


================================================
FILE: cmd/gotype/gotype.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// gotype.go is a copy of the original source maintained
// in $GOROOT/src/go/types/gotype.go, but with the call
// to types.SizesFor factored out so we can provide a local
// implementation when compiling against Go 1.8 and earlier.
//
// This code is here for the sole purpose of satisfying historic
// references to this location, and for making gotype accessible
// via 'go get'.
//
// Do NOT make changes to this version as they will not be maintained
// (and possibly overwritten). Any changes should be made to the original
// and then ported to here.

/*
The gotype command, like the front-end of a Go compiler, parses and
type-checks a single Go package. Errors are reported if the analysis
fails; otherwise gotype is quiet (unless -v is set).

Without a list of paths, gotype reads from standard input, which
must provide a single Go source file defining a complete package.

With a single directory argument, gotype checks the Go files in
that directory, comprising a single package. Use -t to include the
(in-package) _test.go files. Use -x to type check only external
test files.

Otherwise, each path must be the filename of a Go file belonging
to the same package.

Imports are processed by importing directly from the source of
imported packages (default), or by importing from compiled and
installed packages (by setting -c to the respective compiler).

The -c flag must be set to a compiler ("gc", "gccgo") when type-
checking packages containing imports with relative import paths
(import "./mypkg") because the source importer cannot know which
files to include for such packages.

Usage:

	gotype [flags] [path...]

The flags are:

	-t
		include local test files in a directory (ignored if -x is provided)
	-x
		consider only external test files in a directory
	-e
		report all errors (not just the first 10)
	-v
		verbose mode
	-c
		compiler used for installed packages (gc, gccgo, or source); default: source

Flags controlling additional output:

	-ast
		print AST (forces -seq)
	-trace
		print parse trace (forces -seq)
	-comments
		parse comments (ignored unless -ast or -trace is provided)

Examples:

To check the files a.go, b.go, and c.go:

	gotype a.go b.go c.go

To check an entire package including (in-package) tests in the directory dir and print the processed files:

	gotype -t -v dir

To check the external test package (if any) in the current directory, based on installed packages compiled with
cmd/compile:

	gotype -c=gc -x .

To verify the output of a pipe:

	echo "package foo" | gotype
*/
package main

import (
	"flag"
	"fmt"
	"go/ast"
	"go/build"
	"go/importer"
	"go/parser"
	"go/scanner"
	"go/token"
	"go/types"
	"io"
	"os"
	"path/filepath"
	"sync"
	"time"
)

var (
	// main operation modes
	testFiles  = flag.Bool("t", false, "include in-package test files in a directory")
	xtestFiles = flag.Bool("x", false, "consider only external test files in a directory")
	allErrors  = flag.Bool("e", false, "report all errors, not just the first 10")
	verbose    = flag.Bool("v", false, "verbose mode")
	compiler   = flag.String("c", defaultCompiler, "compiler used for installed packages (gc, gccgo, or source)")

	// additional output control
	printAST      = flag.Bool("ast", false, "print AST (forces -seq)")
	printTrace    = flag.Bool("trace", false, "print parse trace (forces -seq)")
	parseComments = flag.Bool("comments", false, "parse comments (ignored unless -ast or -trace is provided)")
)

var (
	fset       = token.NewFileSet()
	errorCount = 0
	sequential = false
	parserMode parser.Mode
)

func initParserMode() {
	if *allErrors {
		parserMode |= parser.AllErrors
	}
	if *printAST {
		sequential = true
	}
	if *printTrace {
		parserMode |= parser.Trace
		sequential = true
	}
	if *parseComments && (*printAST || *printTrace) {
		parserMode |= parser.ParseComments
	}
}

const usageString = `usage: gotype [flags] [path ...]

The gotype command, like the front-end of a Go compiler, parses and
type-checks a single Go package. Errors are reported if the analysis
fails; otherwise gotype is quiet (unless -v is set).

Without a list of paths, gotype reads from standard input, which
must provide a single Go source file defining a complete package.

With a single directory argument, gotype checks the Go files in
that directory, comprising a single package. Use -t to include the
(in-package) _test.go files. Use -x to type check only external
test files.

Otherwise, each path must be the filename of a Go file belonging
to the same package.

Imports are processed by importing directly from the source of
imported packages (default), or by importing from compiled and
installed packages (by setting -c to the respective compiler).

The -c flag must be set to a compiler ("gc", "gccgo") when type-
checking packages containing imports with relative import paths
(import "./mypkg") because the source importer cannot know which
files to include for such packages.
`

func usage() {
	fmt.Fprint(os.Stderr, usageString)
	fmt.Fprintln(os.Stderr)
	flag.PrintDefaults()
	os.Exit(2)
}

func report(err error) {
	scanner.PrintError(os.Stderr, err)
	if list, ok := err.(scanner.ErrorList); ok {
		errorCount += len(list)
		return
	}
	errorCount++
}

// parse may be called concurrently
func parse(filename string, src any) (*ast.File, error) {
	if *verbose {
		fmt.Println(filename)
	}
	file, err := parser.ParseFile(fset, filename, src, parserMode) // ok to access fset concurrently
	if *printAST {
		ast.Print(fset, file)
	}
	return file, err
}

func parseStdin() (*ast.File, error) {
	src, err := io.ReadAll(os.Stdin)
	if err != nil {
		return nil, err
	}
	return parse("<standard input>", src)
}

func parseFiles(dir string, filenames []string) ([]*ast.File, error) {
	files := make([]*ast.File, len(filenames))
	errors := make([]error, len(filenames))

	var wg sync.WaitGroup
	for i, filename := range filenames {
		wg.Add(1)
		go func(i int, filepath string) {
			defer wg.Done()
			files[i], errors[i] = parse(filepath, nil)
		}(i, filepath.Join(dir, filename))
		if sequential {
			wg.Wait()
		}
	}
	wg.Wait()

	// if there are errors, return the first one for deterministic results
	for _, err := range errors {
		if err != nil {
			return nil, err
		}
	}

	return files, nil
}

func parseDir(dir string) ([]*ast.File, error) {
	ctxt := build.Default
	pkginfo, err := ctxt.ImportDir(dir, 0)
	if _, nogo := err.(*build.NoGoError); err != nil && !nogo {
		return nil, err
	}

	if *xtestFiles {
		return parseFiles(dir, pkginfo.XTestGoFiles)
	}

	filenames := append(pkginfo.GoFiles, pkginfo.CgoFiles...)
	if *testFiles {
		filenames = append(filenames, pkginfo.TestGoFiles...)
	}
	return parseFiles(dir, filenames)
}

func getPkgFiles(args []string) ([]*ast.File, error) {
	if len(args) == 0 {
		// stdin
		file, err := parseStdin()
		if err != nil {
			return nil, err
		}
		return []*ast.File{file}, nil
	}

	if len(args) == 1 {
		// possibly a directory
		path := args[0]
		info, err := os.Stat(path)
		if err != nil {
			return nil, err
		}
		if info.IsDir() {
			return parseDir(path)
		}
	}

	// list of files
	return parseFiles("", args)
}

func checkPkgFiles(files []*ast.File) {
	type bailout struct{}

	// if checkPkgFiles is called multiple times, set up conf only once
	conf := types.Config{
		FakeImportC: true,
		Error: func(err error) {
			if !*allErrors && errorCount >= 10 {
				panic(bailout{})
			}
			report(err)
		},
		Importer: importer.ForCompiler(fset, *compiler, nil),
		Sizes:    SizesFor(build.Default.Compiler, build.Default.GOARCH),
	}

	defer func() {
		switch p := recover().(type) {
		case nil, bailout:
			// normal return or early exit
		default:
			// re-panic
			panic(p)
		}
	}()

	const path = "pkg" // any non-empty string will do for now
	conf.Check(path, fset, files, nil)
}

func printStats(d time.Duration) {
	fileCount := 0
	lineCount := 0
	fset.Iterate(func(f *token.File) bool {
		fileCount++
		lineCount += f.LineCount()
		return true
	})

	fmt.Printf(
		"%s (%d files, %d lines, %d lines/s)\n",
		d, fileCount, lineCount, int64(float64(lineCount)/d.Seconds()),
	)
}

func main() {
	flag.Usage = usage
	flag.Parse()
	initParserMode()

	start := time.Now()

	files, err := getPkgFiles(flag.Args())
	if err != nil {
		report(err)
		os.Exit(2)
	}

	checkPkgFiles(files)
	if errorCount > 0 {
		os.Exit(2)
	}

	if *verbose {
		printStats(time.Since(start))
	}
}


================================================
FILE: cmd/gotype/sizesFor18.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.9

// This file contains a copy of the implementation of types.SizesFor
// since this function is not available in go/types before Go 1.9.

package main

import "go/types"

const defaultCompiler = "gc"

var gcArchSizes = map[string]*types.StdSizes{
	"386":      {4, 4},
	"arm":      {4, 4},
	"arm64":    {8, 8},
	"amd64":    {8, 8},
	"amd64p32": {4, 8},
	"mips":     {4, 4},
	"mipsle":   {4, 4},
	"mips64":   {8, 8},
	"mips64le": {8, 8},
	"ppc64":    {8, 8},
	"ppc64le":  {8, 8},
	"s390x":    {8, 8},
}

func SizesFor(compiler, arch string) types.Sizes {
	if compiler != "gc" {
		return nil
	}
	s, ok := gcArchSizes[arch]
	if !ok {
		return nil
	}
	return s
}


================================================
FILE: cmd/gotype/sizesFor19.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.9

package main

import "go/types"

const defaultCompiler = "source"

func SizesFor(compiler, arch string) types.Sizes {
	return types.SizesFor(compiler, arch)
}


================================================
FILE: cmd/goyacc/doc.go
================================================
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Goyacc is a version of yacc for Go.
It is written in Go and generates parsers written in Go.

Usage:

	goyacc args...

It is largely transliterated from the Inferno version written in Limbo
which in turn was largely transliterated from the Plan 9 version
written in C and documented at

	https://9p.io/magic/man2html/1/yacc

Adepts of the original yacc will have no trouble adapting to this
form of the tool.

The directory $GOPATH/src/golang.org/x/tools/cmd/goyacc/testdata/expr
is a yacc program for a very simple expression parser. See expr.y and
main.go in that directory for examples of how to write and build
goyacc programs.

The generated parser is reentrant. The parsing function yyParse expects
to be given an argument that conforms to the following interface:

	type yyLexer interface {
		Lex(lval *yySymType) int
		Error(e string)
	}

Lex should return the token identifier, and place other token
information in lval (which replaces the usual yylval).
Error is equivalent to yyerror in the original yacc.

Code inside the grammar actions may refer to the variable yylex,
which holds the yyLexer passed to yyParse.

Clients that need to understand more about the parser state can
create the parser separately from invoking it. The function yyNewParser
returns a yyParser conforming to the following interface:

	type yyParser interface {
		Parse(yyLex) int
		Lookahead() int
	}

Parse runs the parser; the top-level call yyParse(yylex) is equivalent
to yyNewParser().Parse(yylex).

Lookahead can be called during grammar actions to read (but not consume)
the value of the current lookahead token, as returned by yylex.Lex.
If there is no current lookahead token (because the parser has not called Lex
or has consumed the token returned by the most recent call to Lex),
Lookahead returns -1. Calling Lookahead is equivalent to reading
yychar from within in a grammar action.

Multiple grammars compiled into a single program should be placed in
distinct packages.  If that is impossible, the "-p prefix" flag to
goyacc sets the prefix, by default yy, that begins the names of
symbols, including types, the parser, and the lexer, generated and
referenced by yacc's generated code.  Setting it to distinct values
allows multiple grammars to be placed in a single package.
*/
package main


================================================
FILE: cmd/goyacc/testdata/expr/README
================================================
This directory contains a simple program demonstrating how to use
the Go version of yacc.

To build it:

	$ go generate
	$ go build

or

	$ go generate
	$ go run expr.go

The file main.go contains the "go generate" command to run yacc to
create expr.go from expr.y. It also has the package doc comment,
as godoc will not scan the .y file.

The actual implementation is in expr.y.

The program is not installed in the binary distributions of Go.


================================================
FILE: cmd/goyacc/testdata/expr/expr.y
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is an example of a goyacc program.
// To build it:
// goyacc -p "expr" expr.y (produces y.go)
// go build -o expr y.go
// expr
// > <type an expression>

%{

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"log"
	"math/big"
	"os"
	"unicode/utf8"
)

%}

%union {
	num *big.Rat
}

%type	<num>	expr expr1 expr2 expr3

%token '+' '-' '*' '/' '(' ')'

%token	<num>	NUM

%%

top:
	expr
	{
		if $1.IsInt() {
			fmt.Println($1.Num().String())
		} else {
			fmt.Println($1.String())
		}
	}

expr:
	expr1
|	'+' expr
	{
		$$ = $2
	}
|	'-' expr
	{
		$$ = $2.Neg($2)
	}

expr1:
	expr2
|	expr1 '+' expr2
	{
		$$ = $1.Add($1, $3)
	}
|	expr1 '-' expr2
	{
		$$ = $1.Sub($1, $3)
	}

expr2:
	expr3
|	expr2 '*' expr3
	{
		$$ = $1.Mul($1, $3)
	}
|	expr2 '/' expr3
	{
		$$ = $1.Quo($1, $3)
	}

expr3:
	NUM
|	'(' expr ')'
	{
		$$ = $2
	}


%%

// The parser expects the lexer to return 0 on EOF.  Give it a name
// for clarity.
const eof = 0

// The parser uses the type <prefix>Lex as a lexer. It must provide
// the methods Lex(*<prefix>SymType) int and Error(string).
type exprLex struct {
	line []byte
	peek rune
}

// The parser calls this method to get each new token. This
// implementation returns operators and NUM.
func (x *exprLex) Lex(yylval *exprSymType) int {
	for {
		c := x.next()
		switch c {
		case eof:
			return eof
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			return x.num(c, yylval)
		case '+', '-', '*', '/', '(', ')':
			return int(c)

		// Recognize Unicode multiplication and division
		// symbols, returning what the parser expects.
		case '×':
			return '*'
		case '÷':
			return '/'

		case ' ', '\t', '\n', '\r':
		default:
			log.Printf("unrecognized character %q", c)
		}
	}
}

// Lex a number.
func (x *exprLex) num(c rune, yylval *exprSymType) int {
	add := func(b *bytes.Buffer, c rune) {
		if _, err := b.WriteRune(c); err != nil {
			log.Fatalf("WriteRune: %s", err)
		}
	}
	var b bytes.Buffer
	add(&b, c)
	L: for {
		c = x.next()
		switch c {
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.', 'e', 'E':
			add(&b, c)
		default:
			break L
		}
	}
	if c != eof {
		x.peek = c
	}
	yylval.num = &big.Rat{}
	_, ok := yylval.num.SetString(b.String())
	if !ok {
		log.Printf("bad number %q", b.String())
		return eof
	}
	return NUM
}

// Return the next rune for the lexer.
func (x *exprLex) next() rune {
	if x.peek != eof {
		r := x.peek
		x.peek = eof
		return r
	}
	if len(x.line) == 0 {
		return eof
	}
	c, size := utf8.DecodeRune(x.line)
	x.line = x.line[size:]
	if c == utf8.RuneError && size == 1 {
		log.Print("invalid utf8")
		return x.next()
	}
	return c
}

// The parser calls this method on a parse error.
func (x *exprLex) Error(s string) {
	log.Printf("parse error: %s", s)
}

func main() {
	in := bufio.NewReader(os.Stdin)
	for {
		if _, err := os.Stdout.WriteString("> "); err != nil {
			log.Fatalf("WriteString: %s", err)
		}
		line, err := in.ReadBytes('\n')
		if err == io.EOF {
			return
		}
		if err != nil {
			log.Fatalf("ReadBytes: %s", err)
		}

		exprParse(&exprLex{line: line})
	}
}


================================================
FILE: cmd/goyacc/testdata/expr/main.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file holds the go generate command to run yacc on the grammar in expr.y.
// To build expr:
//	% go generate
//	% go build

//go:generate goyacc -o expr.go -p "expr" expr.y

// Expr is a simple expression evaluator that serves as a working example of
// how to use Go's yacc implementation.
package main


================================================
FILE: cmd/goyacc/yacc.go
================================================
/*
Derived from Inferno's utils/iyacc/yacc.c
http://code.google.com/p/inferno-os/source/browse/utils/iyacc/yacc.c

This copyright NOTICE applies to all files in this directory and
subdirectories, unless another copyright notice appears in a given
file or subdirectory.  If you take substantial code from this software to use in
other programs, you must somehow include with it an appropriate
copyright notice that includes the copyright notice and the other
notices below.  It is fine (and often tidier) to do that in a separate
file such as NOTICE, LICENCE or COPYING.

	Copyright © 1994-1999 Lucent Technologies Inc.  All rights reserved.
	Portions Copyright © 1995-1997 C H Forsyth (forsyth@terzarima.net)
	Portions Copyright © 1997-1999 Vita Nuova Limited
	Portions Copyright © 2000-2007 Vita Nuova Holdings Limited (www.vitanuova.com)
	Portions Copyright © 2004,2006 Bruce Ellis
	Portions Copyright © 2005-2007 C H Forsyth (forsyth@terzarima.net)
	Revisions Copyright © 2000-2007 Lucent Technologies Inc. and others
	Portions Copyright © 2009 The Go Authors. All rights reserved.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package main

// yacc
// major difference is lack of stem ("y" variable)
//

import (
	"bufio"
	"bytes"
	"flag"
	"fmt"
	"go/format"
	"math"
	"os"
	"slices"
	"strconv"
	"strings"
	"unicode"
)

// the following are adjustable
// according to memory size
const (
	ACTSIZE  = 240000
	NSTATES  = 16000
	TEMPSIZE = 16000

	SYMINC   = 50  // increase for non-term or term
	RULEINC  = 50  // increase for max rule length prodptr[i]
	PRODINC  = 100 // increase for productions     prodptr
	WSETINC  = 50  // increase for working sets    wsets
	STATEINC = 200 // increase for states          statemem

	PRIVATE = 0xE000 // unicode private use

	// relationships which must hold:
	//	TEMPSIZE >= NTERMS + NNONTERM + 1;
	//	TEMPSIZE >= NSTATES;
	//

	NTBASE     = 010000
	ERRCODE    = 8190
	ACCEPTCODE = 8191
	YYLEXUNK   = 3
	TOKSTART   = 4 //index of first defined token
)

// no, left, right, binary assoc.
const (
	NOASC = iota
	LASC
	RASC
	BASC
)

// flags for state generation
const (
	DONE = iota
	MUSTDO
	MUSTLOOKAHEAD
)

// flags for a rule having an action, and being reduced
const (
	ACTFLAG = 1 << (iota + 2)
	REDFLAG
)

// output parser flags
const yyFlag = -1000

// parse tokens
const (
	IDENTIFIER = PRIVATE + iota
	MARK
	TERM
	LEFT
	RIGHT
	BINARY
	PREC
	LCURLY
	IDENTCOLON
	NUMBER
	START
	TYPEDEF
	TYPENAME
	UNION
	ERROR
)

const ENDFILE = 0
const EMPTY = 1
const WHOKNOWS = 0
const OK = 1
const NOMORE = -1000

// macros for getting associativity and precedence levels
func ASSOC(i int) int { return i & 3 }

func PLEVEL(i int) int { return (i >> 4) & 077 }

func TYPE(i int) int { return (i >> 10) & 077 }

// macros for setting associativity and precedence levels
func SETASC(i, j int) int { return i | j }

func SETPLEV(i, j int) int { return i | (j << 4) }

func SETTYPE(i, j int) int { return i | (j << 10) }

// I/O descriptors
var finput *bufio.Reader // input file
var stderr *bufio.Writer
var ftable *bufio.Writer    // y.go file
var fcode = &bytes.Buffer{} // saved code
var foutput *bufio.Writer   // y.output file

var fmtImported bool // output file has recorded an import of "fmt"

var oflag string  // -o [y.go]		- y.go file
var vflag string  // -v [y.output]	- y.output file
var lflag bool    // -l			- disable line directives
var prefix string // name prefix for identifiers, default yy

func init() {
	flag.StringVar(&oflag, "o", "y.go", "parser output")
	flag.StringVar(&prefix, "p", "yy", "name prefix to use in generated code")
	flag.StringVar(&vflag, "v", "y.output", "create parsing tables")
	flag.BoolVar(&lflag, "l", false, "disable line directives")
}

var initialstacksize = 16

// communication variables between various I/O routines
var infile string  // input file name
var numbval int    // value of an input number
var tokname string // input token name, slop for runes and 0
var tokflag = false

// structure declarations
type Lkset []int

type Pitem struct {
	prod   []int
	off    int // offset within the production
	first  int // first term or non-term in item
	prodno int // production number for sorting
}

type Item struct {
	pitem Pitem
	look  Lkset
}

type Symb struct {
	name    string
	noconst bool
	value   int
}

type Wset struct {
	pitem Pitem
	flag  int
	ws    Lkset
}

// storage of types
var ntypes int                     // number of types defined
var typeset = make(map[int]string) // pointers to type tags

// token information

var ntokens = 0 // number of tokens
var tokset []Symb
var toklev []int // vector with the precedence of the terminals

// nonterminal information

var nnonter = -1 // the number of nonterminals
var nontrst []Symb
var start int // start symbol

// state information

var nstate = 0                      // number of states
var pstate = make([]int, NSTATES+2) // index into statemem to the descriptions of the states
var statemem []Item
var tystate = make([]int, NSTATES) // contains type information about the states
var tstates []int                  // states generated by terminal gotos
var ntstates []int                 // states generated by nonterminal gotos
var mstates = make([]int, NSTATES) // chain of overflows of term/nonterm generation lists
var lastred int                    // number of last reduction of a state
var defact = make([]int, NSTATES)  // default actions of states

// lookahead set information

var nolook = 0  // flag to turn off lookahead computations
var tbitset = 0 // size of lookahead sets
var clset Lkset // temporary storage for lookahead computations

// working set information

var wsets []Wset
var cwp int

// storage for action table

var amem []int                   // action table storage
var memp int                     // next free action table position
var indgo = make([]int, NSTATES) // index to the stored goto table

// temporary vector, indexable by states, terms, or ntokens

var temp1 = make([]int, TEMPSIZE) // temporary storage, indexed by terms + ntokens or states
var lineno = 1                    // current input line number
var fatfl = 1                     // if on, error is fatal
var nerrors = 0                   // number of errors

// assigned token type values

var extval = 0

// grammar rule information

var nprod = 1      // number of productions
var prdptr [][]int // pointers to descriptions of productions
var levprd []int   // precedence levels for the productions
var rlines []int   // line number for this rule

// statistics collection variables

var zzgoent = 0
var zzgobest = 0
var zzacent = 0
var zzexcp = 0
var zzclose = 0
var zzrrconf = 0
var zzsrconf = 0
var zzstate = 0

// optimizer arrays

var yypgo [][]int
var optst [][]int
var ggreed []int
var pgo []int

var maxspr int // maximum spread of any entry
var maxoff int // maximum offset into a array
var maxa int

// storage for information about the nonterminals

var pres [][][]int // vector of pointers to productions yielding each nonterminal
var pfirst []Lkset
var pempty []int // vector of nonterminals nontrivially deriving e

// random stuff picked out from between functions

var indebug = 0 // debugging flag for cpfir
var pidebug = 0 // debugging flag for putitem
var gsdebug = 0 // debugging flag for stagen
var cldebug = 0 // debugging flag for closure
var pkdebug = 0 // debugging flag for apack
var g2debug = 0 // debugging for go2gen
var adb = 0     // debugging for callopt

type Resrv struct {
	name  string
	value int
}

var resrv = []Resrv{
	{"binary", BINARY},
	{"left", LEFT},
	{"nonassoc", BINARY},
	{"prec", PREC},
	{"right", RIGHT},
	{"start", START},
	{"term", TERM},
	{"token", TERM},
	{"type", TYPEDEF},
	{"union", UNION},
	{"struct", UNION},
	{"error", ERROR},
}

type Error struct {
	lineno int
	tokens []string
	msg    string
}

var errors []Error

type Row struct {
	actions       []int
	defaultAction int
}

var stateTable []Row

var zznewstate = 0

const EOF = -1

func main() {

	setup() // initialize and read productions

	tbitset = (ntokens + 32) / 32
	cpres()  // make table of which productions yield a given nonterminal
	cempty() // make a table of which nonterminals can match the empty string
	cpfir()  // make a table of firsts of nonterminals

	stagen() // generate the states

	yypgo = make([][]int, nnonter+1)
	optst = make([][]int, nstate)
	output() // write the states and the tables
	go2out()

	hideprod()
	summary()

	callopt()

	others()

	exit(0)
}

func setup() {
	var j, ty int

	stderr = bufio.NewWriter(os.Stderr)
	foutput = nil

	flag.Parse()
	if flag.NArg() != 1 {
		usage()
	}
	if initialstacksize < 1 {
		// never set so cannot happen
		fmt.Fprintf(stderr, "yacc: stack size too small\n")
		usage()
	}
	yaccpar = strings.Replace(yaccpartext, "$$", prefix, -1)
	openup()

	fmt.Fprintf(ftable, "// Code generated by goyacc %s. DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))

	defin(0, "$end")
	extval = PRIVATE // tokens start in unicode 'private use'
	defin(0, "error")
	defin(1, "$accept")
	defin(0, "$unk")
	i := 0

	t := gettok()

outer:
	for {
		switch t {
		default:
			errorf("syntax error tok=%v", t-PRIVATE)

		case MARK, ENDFILE:
			break outer

		case ';':
			// Do nothing.

		case START:
			t = gettok()
			if t != IDENTIFIER {
				errorf("bad %%start construction")
			}
			start = chfind(1, tokname)

		case ERROR:
			lno := lineno
			var tokens []string
			for {
				t := gettok()
				if t == ':' {
					break
				}
				if t != IDENTIFIER && t != IDENTCOLON {
					errorf("bad syntax in %%error")
				}
				tokens = append(tokens, tokname)
				if t == IDENTCOLON {
					break
				}
			}
			if gettok() != IDENTIFIER {
				errorf("bad syntax in %%error")
			}
			errors = append(errors, Error{lno, tokens, tokname})

		case TYPEDEF:
			t = gettok()
			if t != TYPENAME {
				errorf("bad syntax in %%type")
			}
			ty = numbval
			for {
				t = gettok()
				switch t {
				case IDENTIFIER:
					t = chfind(1, tokname)
					if t < NTBASE {
						j = TYPE(toklev[t])
						if j != 0 && j != ty {
							errorf("type redeclaration of token %s",
								tokset[t].name)
						} else {
							toklev[t] = SETTYPE(toklev[t], ty)
						}
					} else {
						j = nontrst[t-NTBASE].value
						if j != 0 && j != ty {
							errorf("type redeclaration of nonterminal %v",
								nontrst[t-NTBASE].name)
						} else {
							nontrst[t-NTBASE].value = ty
						}
					}
					continue

				case ',':
					continue
				}
				break
			}
			continue

		case UNION:
			cpyunion()

		case LEFT, BINARY, RIGHT, TERM:
			// nonzero means new prec. and assoc.
			lev := t - TERM
			if lev != 0 {
				i++
			}
			ty = 0

			// get identifiers so defined
			t = gettok()

			// there is a type defined
			if t == TYPENAME {
				ty = numbval
				t = gettok()
			}
			for {
				switch t {
				case ',':
					t = gettok()
					continue

				case ';':
					// Do nothing.

				case IDENTIFIER:
					j = chfind(0, tokname)
					if j >= NTBASE {
						errorf("%v defined earlier as nonterminal", tokname)
					}
					if lev != 0 {
						if ASSOC(toklev[j]) != 0 {
							errorf("redeclaration of precedence of %v", tokname)
						}
						toklev[j] = SETASC(toklev[j], lev)
						toklev[j] = SETPLEV(toklev[j], i)
					}
					if ty != 0 {
						if TYPE(toklev[j]) != 0 {
							errorf("redeclaration of type of %v", tokname)
						}
						toklev[j] = SETTYPE(toklev[j], ty)
					}
					t = gettok()
					if t == NUMBER {
						tokset[j].value = numbval
						t = gettok()
					}

					continue
				}
				break
			}
			continue

		case LCURLY:
			cpycode()
		}
		t = gettok()
	}

	if t == ENDFILE {
		errorf("unexpected EOF before %%")
	}

	fmt.Fprintf(fcode, "switch %snt {\n", prefix)

	moreprod()
	prdptr[0] = []int{NTBASE, start, 1, 0}

	nprod = 1
	curprod := make([]int, RULEINC)
	t = gettok()
	if t != IDENTCOLON {
		errorf("bad syntax on first rule")
	}

	if start == 0 {
		prdptr[0][1] = chfind(1, tokname)
	}

	// read rules
	// put into prdptr array in the format
	// target
	// followed by id's of terminals and non-terminals
	// followed by -nprod

	for t != MARK && t != ENDFILE {
		mem := 0

		// process a rule
		rlines[nprod] = lineno
		ruleline := lineno
		if t == '|' {
			curprod[mem] = prdptr[nprod-1][0]
			mem++
		} else if t == IDENTCOLON {
			curprod[mem] = chfind(1, tokname)
			if curprod[mem] < NTBASE {
				lerrorf(ruleline, "token illegal on LHS of grammar rule")
			}
			mem++
		} else {
			lerrorf(ruleline, "illegal rule: missing semicolon or | ?")
		}

		// read rule body
		t = gettok()
		for {
			for t == IDENTIFIER {
				curprod[mem] = chfind(1, tokname)
				if curprod[mem] < NTBASE {
					levprd[nprod] = toklev[curprod[mem]]
				}
				mem++
				if mem >= len(curprod) {
					ncurprod := make([]int, mem+RULEINC)
					copy(ncurprod, curprod)
					curprod = ncurprod
				}
				t = gettok()
			}
			if t == PREC {
				if gettok() != IDENTIFIER {
					lerrorf(ruleline, "illegal %%prec syntax")
				}
				j = chfind(2, tokname)
				if j >= NTBASE {
					lerrorf(ruleline, "nonterminal %s illegal after %%prec", nontrst[j-NTBASE].name)
				}
				levprd[nprod] = toklev[j]
				t = gettok()
			}
			if t != '=' {
				break
			}
			levprd[nprod] |= ACTFLAG
			fmt.Fprintf(fcode, "\n\tcase %v:", nprod)
			fmt.Fprintf(fcode, "\n\t\t%sDollar = %sS[%spt-%v:%spt+1]", prefix, prefix, prefix, mem-1, prefix)
			cpyact(curprod, mem)

			// action within rule...
			t = gettok()
			if t == IDENTIFIER {
				// make it a nonterminal
				j = chfind(1, fmt.Sprintf("$$%v", nprod))

				//
				// the current rule will become rule number nprod+1
				// enter null production for action
				//
				prdptr[nprod] = make([]int, 2)
				prdptr[nprod][0] = j
				prdptr[nprod][1] = -nprod

				// update the production information
				nprod++
				moreprod()
				levprd[nprod] = levprd[nprod-1] & ^ACTFLAG
				levprd[nprod-1] = ACTFLAG
				rlines[nprod] = lineno

				// make the action appear in the original rule
				curprod[mem] = j
				mem++
				if mem >= len(curprod) {
					ncurprod := make([]int, mem+RULEINC)
					copy(ncurprod, curprod)
					curprod = ncurprod
				}
			}
		}

		for t == ';' {
			t = gettok()
		}
		curprod[mem] = -nprod
		mem++

		// check that default action is reasonable
		if ntypes != 0 && (levprd[nprod]&ACTFLAG) == 0 &&
			nontrst[curprod[0]-NTBASE].value != 0 {
			// no explicit action, LHS has value
			tempty := curprod[1]
			if tempty < 0 {
				lerrorf(ruleline, "must return a value, since LHS has a type")
			}
			if tempty >= NTBASE {
				tempty = nontrst[tempty-NTBASE].value
			} else {
				tempty = TYPE(toklev[tempty])
			}
			if tempty != nontrst[curprod[0]-NTBASE].value {
				lerrorf(ruleline, "default action causes potential type clash")
			}
		}
		moreprod()
		prdptr[nprod] = make([]int, mem)
		copy(prdptr[nprod], curprod)
		nprod++
		moreprod()
		levprd[nprod] = 0
	}

	if TEMPSIZE < ntokens+nnonter+1 {
		errorf("too many tokens (%d) or non-terminals (%d)", ntokens, nnonter)
	}

	//
	// end of all rules
	// dump out the prefix code
	//

	fmt.Fprintf(fcode, "\n\t}")

	// put out non-literal terminals
	for i := TOKSTART; i <= ntokens; i++ {
		// non-literals
		if !tokset[i].noconst {
			fmt.Fprintf(ftable, "const %v = %v\n", tokset[i].name, tokset[i].value)
		}
	}

	// put out names of tokens
	ftable.WriteRune('\n')
	fmt.Fprintf(ftable, "var %sToknames = [...]string{\n", prefix)
	for i := 1; i <= ntokens; i++ {
		fmt.Fprintf(ftable, "\t%q,\n", tokset[i].name)
	}
	fmt.Fprintf(ftable, "}\n")

	// put out names of states.
	// commented out to avoid a huge table just for debugging.
	// re-enable to have the names in the binary.
	ftable.WriteRune('\n')
	fmt.Fprintf(ftable, "var %sStatenames = [...]string{\n", prefix)
	//	for i:=TOKSTART; i<=ntokens; i++ {
	//		fmt.Fprintf(ftable, "\t%q,\n", tokset[i].name);
	//	}
	fmt.Fprintf(ftable, "}\n")

	ftable.WriteRune('\n')
	fmt.Fprintf(ftable, "const %sEofCode = 1\n", prefix)
	fmt.Fprintf(ftable, "const %sErrCode = 2\n", prefix)
	fmt.Fprintf(ftable, "const %sInitialStackSize = %v\n", prefix, initialstacksize)

	//
	// copy any postfix code
	//
	if t == MARK {
		if !lflag {
			fmt.Fprintf(ftable, "\n//line %v:%v\n", infile, lineno)
		}
		for {
			c := getrune(finput)
			if c == EOF {
				break
			}
			ftable.WriteRune(c)
		}
	}
}

// allocate enough room to hold another production
func moreprod() {
	n := len(prdptr)
	if nprod >= n {
		nn := n + PRODINC
		aprod := make([][]int, nn)
		alevprd := make([]int, nn)
		arlines := make([]int, nn)

		copy(aprod, prdptr)
		copy(alevprd, levprd)
		copy(arlines, rlines)

		prdptr = aprod
		levprd = alevprd
		rlines = arlines
	}
}

// define s to be a terminal if nt==0
// or a nonterminal if nt==1
func defin(nt int, s string) int {
	val := 0
	if nt != 0 {
		nnonter++
		if nnonter >= len(nontrst) {
			anontrst := make([]Symb, nnonter+SYMINC)
			copy(anontrst, nontrst)
			nontrst = anontrst
		}
		nontrst[nnonter] = Symb{name: s}
		return NTBASE + nnonter
	}

	// must be a token
	ntokens++
	if ntokens >= len(tokset) {
		nn := ntokens + SYMINC
		atokset := make([]Symb, nn)
		atoklev := make([]int, nn)

		copy(atoklev, toklev)
		copy(atokset, tokset)

		tokset = atokset
		toklev = atoklev
	}
	tokset[ntokens].name = s
	toklev[ntokens] = 0

	// establish value for token
	// single character literal
	if s[0] == '\'' || s[0] == '"' {
		q, err := strconv.Unquote(s)
		if err != nil {
			errorf("invalid token: %s", err)
		}
		rq := []rune(q)
		if len(rq) != 1 {
			errorf("character token too long: %s", s)
		}
		val = int(rq[0])
		if val == 0 {
			errorf("token value 0 is illegal")
		}
		tokset[ntokens].noconst = true
	} else {
		val = extval
		extval++
		if s[0] == '$' {
			tokset[ntokens].noconst = true
		}
	}

	tokset[ntokens].value = val
	return ntokens
}

var peekline = 0

func gettok() int {
	var i int
	var match, c rune

	tokname = ""
	for {
		lineno += peekline
		peekline = 0
		c = getrune(finput)
		for c == ' ' || c == '\n' || c == '\t' || c == '\v' || c == '\r' {
			if c == '\n' {
				lineno++
			}
			c = getrune(finput)
		}

		// skip comment -- fix
		if c != '/' {
			break
		}
		lineno += skipcom()
	}

	switch c {
	case EOF:
		if tokflag {
			fmt.Printf(">>> ENDFILE %v\n", lineno)
		}
		return ENDFILE

	case '{':
		ungetrune(finput, c)
		if tokflag {
			fmt.Printf(">>> ={ %v\n", lineno)
		}
		return '='

	case '<':
		// get, and look up, a type name (union member name)
		c = getrune(finput)
		for c != '>' && c != EOF && c != '\n' {
			tokname += string(c)
			c = getrune(finput)
		}

		if c != '>' {
			errorf("unterminated < ... > clause")
		}

		for i = 1; i <= ntypes; i++ {
			if typeset[i] == tokname {
				numbval = i
				if tokflag {
					fmt.Printf(">>> TYPENAME old <%v> %v\n", tokname, lineno)
				}
				return TYPENAME
			}
		}
		ntypes++
		numbval = ntypes
		typeset[numbval] = tokname
		if tokflag {
			fmt.Printf(">>> TYPENAME new <%v> %v\n", tokname, lineno)
		}
		return TYPENAME

	case '"', '\'':
		match = c
		tokname = string(c)
		for {
			c = getrune(finput)
			if c == '\n' || c == EOF {
				errorf("illegal or missing ' or \"")
			}
			if c == '\\' {
				tokname += string('\\')
				c = getrune(finput)
			} else if c == match {
				if tokflag {
					fmt.Printf(">>> IDENTIFIER \"%v\" %v\n", tokname, lineno)
				}
				tokname += string(c)
				return IDENTIFIER
			}
			tokname += string(c)
		}

	case '%':
		c = getrune(finput)
		switch c {
		case '%':
			if tokflag {
				fmt.Printf(">>> MARK %%%% %v\n", lineno)
			}
			return MARK
		case '=':
			if tokflag {
				fmt.Printf(">>> PREC %%= %v\n", lineno)
			}
			return PREC
		case '{':
			if tokflag {
				fmt.Printf(">>> LCURLY %%{ %v\n", lineno)
			}
			return LCURLY
		}

		getword(c)
		// find a reserved word
		for i := range resrv {
			if tokname == resrv[i].name {
				if tokflag {
					fmt.Printf(">>> %%%v %v %v\n", tokname,
						resrv[i].value-PRIVATE, lineno)
				}
				return resrv[i].value
			}
		}
		errorf("invalid escape, or illegal reserved word: %v", tokname)

	case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
		numbval = int(c - '0')
		for {
			c = getrune(finput)
			if !isdigit(c) {
				break
			}
			numbval = numbval*10 + int(c-'0')
		}
		ungetrune(finput, c)
		if tokflag {
			fmt.Printf(">>> NUMBER %v %v\n", numbval, lineno)
		}
		return NUMBER

	default:
		if isword(c) || c == '.' || c == '$' {
			getword(c)
			break
		}
		if tokflag {
			fmt.Printf(">>> OPERATOR %v %v\n", string(c), lineno)
		}
		return int(c)
	}

	// look ahead to distinguish IDENTIFIER from IDENTCOLON
	c = getrune(finput)
	for c == ' ' || c == '\t' || c == '\n' || c == '\v' || c == '\r' || c == '/' {
		if c == '\n' {
			peekline++
		}
		// look for comments
		if c == '/' {
			peekline += skipcom()
		}
		c = getrune(finput)
	}
	if c == ':' {
		if tokflag {
			fmt.Printf(">>> IDENTCOLON %v: %v\n", tokname, lineno)
		}
		return IDENTCOLON
	}

	ungetrune(finput, c)
	if tokflag {
		fmt.Printf(">>> IDENTIFIER %v %v\n", tokname, lineno)
	}
	return IDENTIFIER
}

func getword(c rune) {
	tokname = ""
	for isword(c) || isdigit(c) || c == '.' || c == '$' {
		tokname += string(c)
		c = getrune(finput)
	}
	ungetrune(finput, c)
}

// determine the type of a symbol
func fdtype(t int) int {
	var v int
	var s string

	if t >= NTBASE {
		v = nontrst[t-NTBASE].value
		s = nontrst[t-NTBASE].name
	} else {
		v = TYPE(toklev[t])
		s = tokset[t].name
	}
	if v <= 0 {
		errorf("must specify type for %v", s)
	}
	return v
}

func chfind(t int, s string) int {
	if s[0] == '"' || s[0] == '\'' {
		t = 0
	}
	for i := 0; i <= ntokens; i++ {
		if s == tokset[i].name {
			return i
		}
	}
	for i := 0; i <= nnonter; i++ {
		if s == nontrst[i].name {
			return NTBASE + i
		}
	}

	// cannot find name
	if t > 1 {
		errorf("%v should have been defined earlier", s)
	}
	return defin(t, s)
}

// copy the union declaration to the output, and the define file if present
func cpyunion() {

	if !lflag {
		fmt.Fprintf(ftable, "\n//line %v:%v\n", infile, lineno)
	}
	fmt.Fprintf(ftable, "type %sSymType struct", prefix)

	level := 0

out:
	for {
		c := getrune(finput)
		if c == EOF {
			errorf("EOF encountered while processing %%union")
		}
		ftable.WriteRune(c)
		switch c {
		case '\n':
			lineno++
		case '{':
			if level == 0 {
				fmt.Fprintf(ftable, "\n\tyys int")
			}
			level++
		case '}':
			level--
			if level == 0 {
				break out
			}
		}
	}
	fmt.Fprintf(ftable, "\n\n")
}

// saves code between %{ and %}
// adds an import for __fmt__ the first time
func cpycode() {
	lno := lineno

	c := getrune(finput)
	if c == '\n' {
		c = getrune(finput)
		lineno++
	}
	if !lflag {
		fmt.Fprintf(ftable, "\n//line %v:%v\n", infile, lineno)
	}
	// accumulate until %}
	code := make([]rune, 0, 1024)
	for c != EOF {
		if c == '%' {
			c = getrune(finput)
			if c == '}' {
				emitcode(code, lno+1)
				return
			}
			code = append(code, '%')
		}
		code = append(code, c)
		if c == '\n' {
			lineno++
		}
		c = getrune(finput)
	}
	lineno = lno
	errorf("eof before %%}")
}

// emits code saved up from between %{ and %}
// called by cpycode
// adds an import for __yyfmt__ after the package clause
func emitcode(code []rune, lineno int) {
	for i, line := range lines(code) {
		writecode(line)
		if !fmtImported && isPackageClause(line) {
			fmt.Fprintln(ftable, `import __yyfmt__ "fmt"`)
			if !lflag {
				fmt.Fprintf(ftable, "//line %v:%v\n\t\t", infile, lineno+i)
			}
			fmtImported = true
		}
	}
}

// does this line look like a package clause?  not perfect: might be confused by early comments.
func isPackageClause(line []rune) bool {
	line = skipspace(line)

	// must be big enough.
	if len(line) < len("package X\n") {
		return false
	}

	// must start with "package"
	for i, r := range []rune("package") {
		if line[i] != r {
			return false
		}
	}
	line = skipspace(line[len("package"):])

	// must have another identifier.
	if len(line) == 0 || (!unicode.IsLetter(line[0]) && line[0] != '_') {
		return false
	}
	for len(line) > 0 {
		if !unicode.IsLetter(line[0]) && !unicode.IsDigit(line[0]) && line[0] != '_' {
			break
		}
		line = line[1:]
	}
	line = skipspace(line)

	// eol, newline, or comment must follow
	if len(line) == 0 {
		return true
	}
	if line[0] == '\r' || line[0] == '\n' {
		return true
	}
	if len(line) >= 2 {
		return line[0] == '/' && (line[1] == '/' || line[1] == '*')
	}
	return false
}

// skip initial spaces
func skipspace(line []rune) []rune {
	for len(line) > 0 {
		if line[0] != ' ' && line[0] != '\t' {
			break
		}
		line = line[1:]
	}
	return line
}

// break code into lines
func lines(code []rune) [][]rune {
	l := make([][]rune, 0, 100)
	for len(code) > 0 {
		// one line per loop
		var i int
		for i = range code {
			if code[i] == '\n' {
				break
			}
		}
		l = append(l, code[:i+1])
		code = code[i+1:]
	}
	return l
}

// writes code to ftable
func writecode(code []rune) {
	for _, r := range code {
		ftable.WriteRune(r)
	}
}

// skip over comments
// skipcom is called after reading a '/'
func skipcom() int {
	c := getrune(finput)
	if c == '/' {
		for c != EOF {
			if c == '\n' {
				return 1
			}
			c = getrune(finput)
		}
		errorf("EOF inside comment")
		return 0
	}
	if c != '*' {
		errorf("illegal comment")
	}

	nl := 0 // lines skipped
	c = getrune(finput)

l1:
	switch c {
	case '*':
		c = getrune(finput)
		if c == '/' {
			break
		}
		goto l1

	case '\n':
		nl++
		fallthrough

	default:
		c = getrune(finput)
		goto l1
	}
	return nl
}

// copy action to the next ; or closing }
func cpyact(curprod []int, max int) {

	if !lflag {
		fmt.Fprintf(fcode, "\n//line %v:%v", infile, lineno)
	}
	fmt.Fprint(fcode, "\n\t\t")

	lno := lineno
	brac := 0

loop:
	for {
		c := getrune(finput)

	swt:
		switch c {
		case ';':
			if brac == 0 {
				fcode.WriteRune(c)
				return
			}

		case '{':
			brac++

		case '$':
			s := 1
			tok := -1
			c = getrune(finput)

			// type description
			if c == '<' {
				ungetrune(finput, c)
				if gettok() != TYPENAME {
					errorf("bad syntax on $<ident> clause")
				}
				tok = numbval
				c = getrune(finput)
			}
			if c == '$' {
				fmt.Fprintf(fcode, "%sVAL", prefix)

				// put out the proper tag...
				if ntypes != 0 {
					if tok < 0 {
						tok = fdtype(curprod[0])
					}
					fmt.Fprintf(fcode, ".%v", typeset[tok])
				}
				continue loop
			}
			if c == '-' {
				s = -s
				c = getrune(finput)
			}
			j := 0
			if isdigit(c) {
				for isdigit(c) {
					j = j*10 + int(c-'0')
					c = getrune(finput)
				}
				ungetrune(finput, c)
				j = j * s
				if j >= max {
					errorf("Illegal use of $%v", j)
				}
			} else if isword(c) || c == '.' {
				// look for $name
				ungetrune(finput, c)
				if gettok() != IDENTIFIER {
					errorf("$ must be followed by an identifier")
				}
				tokn := chfind(2, tokname)
				fnd := -1
				c = getrune(finput)
				if c != '@' {
					ungetrune(finput, c)
				} else if gettok() != NUMBER {
					errorf("@ must be followed by number")
				} else {
					fnd = numbval
				}
				for j = 1; j < max; j++ {
					if tokn == curprod[j] {
						fnd--
						if fnd <= 0 {
							break
						}
					}
				}
				if j >= max {
					errorf("$name or $name@number not found")
				}
			} else {
				fcode.WriteRune('$')
				if s < 0 {
					fcode.WriteRune('-')
				}
				ungetrune(finput, c)
				continue loop
			}
			fmt.Fprintf(fcode, "%sDollar[%v]", prefix, j)

			// put out the proper tag
			if ntypes != 0 {
				if j <= 0 && tok < 0 {
					errorf("must specify type of $%v", j)
				}
				if tok < 0 {
					tok = fdtype(curprod[j])
				}
				fmt.Fprintf(fcode, ".%v", typeset[tok])
			}
			continue loop

		case '}':
			brac--
			if brac != 0 {
				break
			}
			fcode.WriteRune(c)
			return

		case '/':
			nc := getrune(finput)
			if nc != '/' && nc != '*' {
				ungetrune(finput, nc)
				break
			}
			// a comment
			fcode.WriteRune(c)
			fcode.WriteRune(nc)
			c = getrune(finput)
			for c != EOF {
				switch {
				case c == '\n':
					lineno++
					if nc == '/' { // end of // comment
						break swt
					}
				case c == '*' && nc == '*': // end of /* comment?
					nnc := getrune(finput)
					if nnc == '/' {
						fcode.WriteRune('*')
						fcode.WriteRune('/')
						continue loop
					}
					ungetrune(finput, nnc)
				}
				fcode.WriteRune(c)
				c = getrune(finput)
			}
			errorf("EOF inside comment")

		case '\'', '"':
			// character string or constant
			match := c
			fcode.WriteRune(c)
			c = getrune(finput)
			for c != EOF {
				if c == '\\' {
					fcode.WriteRune(c)
					c = getrune(finput)
					if c == '\n' {
						lineno++
					}
				} else if c == match {
					break swt
				}
				if c == '\n' {
					errorf("newline in string or char const")
				}
				fcode.WriteRune(c)
				c = getrune(finput)
			}
			errorf("EOF in string or character constant")

		case EOF:
			lineno = lno
			errorf("action does not terminate")

		case '\n':
			fmt.Fprint(fcode, "\n\t")
			lineno++
			continue loop
		}

		fcode.WriteRune(c)
	}
}

func openup() {
	infile = flag.Arg(0)
	finput = open(infile)
	if finput == nil {
		errorf("cannot open %v", infile)
	}

	foutput = nil
	if vflag != "" {
		foutput = create(vflag)
		if foutput == nil {
			errorf("can't create file %v", vflag)
		}
	}

	ftable = nil
	if oflag == "" {
		oflag = "y.go"
	}
	ftable = create(oflag)
	if ftable == nil {
		errorf("can't create file %v", oflag)
	}

}

// return a pointer to the name of symbol i
func symnam(i int) string {
	var s string

	if i >= NTBASE {
		s = nontrst[i-NTBASE].name
	} else {
		s = tokset[i].name
	}
	return s
}

// set elements 0 through n-1 to c
func aryfil(v []int, n, c int) {
	for i := range n {
		v[i] = c
	}
}

// compute an array with the beginnings of productions yielding given nonterminals
// The array pres points to these lists
// the array pyield has the lists: the total size is only NPROD+1
func cpres() {
	pres = make([][][]int, nnonter+1)
	curres := make([][]int, nprod)

	if false {
		for j := 0; j <= nnonter; j++ {
			fmt.Printf("nnonter[%v] = %v\n", j, nontrst[j].name)
		}
		for j := 0; j < nprod; j++ {
			fmt.Printf("prdptr[%v][0] = %v+NTBASE\n", j, prdptr[j][0]-NTBASE)
		}
	}

	fatfl = 0 // make undefined symbols nonfatal
	for i := 0; i <= nnonter; i++ {
		n := 0
		c := i + NTBASE
		for j := 0; j < nprod; j++ {
			if prdptr[j][0] == c {
				curres[n] = prdptr[j][1:]
				n++
			}
		}
		if n == 0 {
			errorf("nonterminal %v not defined", nontrst[i].name)
			continue
		}
		pres[i] = make([][]int, n)
		copy(pres[i], curres)
	}
	fatfl = 1
	if nerrors != 0 {
		summary()
		exit(1)
	}
}

// mark nonterminals which derive the empty string
// also, look for nonterminals which don't derive any token strings
func cempty() {
	var i, p, np int
	var prd []int

	pempty = make([]int, nnonter+1)

	// first, use the array pempty to detect productions that can never be reduced
	// set pempty to WHONOWS
	aryfil(pempty, nnonter+1, WHOKNOWS)

	// now, look at productions, marking nonterminals which derive something
more:
	for {
		for i = 0; i < nprod; i++ {
			prd = prdptr[i]
			if pempty[prd[0]-NTBASE] != 0 {
				continue
			}
			np = len(prd) - 1
			for p = 1; p < np; p++ {
				if prd[p] >= NTBASE && pempty[prd[p]-NTBASE] == WHOKNOWS {
					break
				}
			}
			// production can be derived
			if p == np {
				pempty[prd[0]-NTBASE] = OK
				continue more
			}
		}
		break
	}

	// now, look at the nonterminals, to see if they are all OK
	for i = 0; i <= nnonter; i++ {
		// the added production rises or falls as the start symbol ...
		if i == 0 {
			continue
		}
		if pempty[i] != OK {
			fatfl = 0
			errorf("nonterminal %s never derives any token string", nontrst[i].name)
		}
	}

	if nerrors != 0 {
		summary()
		exit(1)
	}

	// now, compute the pempty array, to see which nonterminals derive the empty string
	// set pempty to WHOKNOWS
	aryfil(pempty, nnonter+1, WHOKNOWS)

	// loop as long as we keep finding empty nonterminals

again:
	for {
	next:
		for i = 1; i < nprod; i++ {
			// not known to be empty
			prd = prdptr[i]
			if pempty[prd[0]-NTBASE] != WHOKNOWS {
				continue
			}
			np = len(prd) - 1
			for p = 1; p < np; p++ {
				if prd[p] < NTBASE || pempty[prd[p]-NTBASE] != EMPTY {
					continue next
				}
			}

			// we have a nontrivially empty nonterminal
			pempty[prd[0]-NTBASE] = EMPTY

			// got one ... try for another
			continue again
		}
		return
	}
}

// compute an array with the first of nonterminals
func cpfir() {
	var s, n, p, np, ch, i int
	var curres [][]int
	var prd []int

	wsets = make([]Wset, nnonter+WSETINC)
	pfirst = make([]Lkset, nnonter+1)
	for i = 0; i <= nnonter; i++ {
		wsets[i].ws = mkset()
		pfirst[i] = mkset()
		curres = pres[i]
		n = len(curres)

		// initially fill the sets
		for s = 0; s < n; s++ {
			prd = curres[s]
			np = len(prd) - 1
			for p = 0; p < np; p++ {
				ch = prd[p]
				if ch < NTBASE {
					setbit(pfirst[i], ch)
					break
				}
				if pempty[ch-NTBASE] == 0 {
					break
				}
			}
		}
	}

	// now, reflect transitivity
	changes := 1
	for changes != 0 {
		changes = 0
		for i = 0; i <= nnonter; i++ {
			curres = pres[i]
			n = len(curres)
			for s = 0; s < n; s++ {
				prd = curres[s]
				np = len(prd) - 1
				for p = 0; p < np; p++ {
					ch = prd[p] - NTBASE
					if ch < 0 {
						break
					}
					changes |= setunion(pfirst[i], pfirst[ch])
					if pempty[ch] == 0 {
						break
					}
				}
			}
		}
	}

	if indebug == 0 {
		return
	}
	if foutput != nil {
		for i = 0; i <= nnonter; i++ {
			fmt.Fprintf(foutput, "\n%v: %v %v\n",
				nontrst[i].name, pfirst[i], pempty[i])
		}
	}
}

// generate the states
func stagen() {
	// initialize
	nstate = 0
	tstates = make([]int, ntokens+1)  // states generated by terminal gotos
	ntstates = make([]int, nnonter+1) // states generated by nonterminal gotos
	amem = make([]int, ACTSIZE)
	memp = 0

	clset = mkset()
	pstate[0] = 0
	pstate[1] = 0
	aryfil(clset, tbitset, 0)
	putitem(Pitem{prdptr[0], 0, 0, 0}, clset)
	tystate[0] = MUSTDO
	nstate = 1
	pstate[2] = pstate[1]

	//
	// now, the main state generation loop
	// first pass generates all of the states
	// later passes fix up lookahead
	// could be sped up a lot by remembering
	// results of the first pass rather than recomputing
	//
	first := 1
	for more := 1; more != 0; first = 0 {
		more = 0
		for i := 0; i < nstate; i++ {
			if tystate[i] != MUSTDO {
				continue
			}

			tystate[i] = DONE
			aryfil(temp1, nnonter+1, 0)

			// take state i, close it, and do gotos
			closure(i)

			// generate goto's
			for p := 0; p < cwp; p++ {
				pi := wsets[p]
				if pi.flag != 0 {
					continue
				}
				wsets[p].flag = 1
				c := pi.pitem.first
				if c <= 1 {
					if pstate[i+1]-pstate[i] <= p {
						tystate[i] = MUSTLOOKAHEAD
					}
					continue
				}

				// do a goto on c
				putitem(wsets[p].pitem, wsets[p].ws)
				for q := p + 1; q < cwp; q++ {
					// this item contributes to the goto
					if c == wsets[q].pitem.first {
						putitem(wsets[q].pitem, wsets[q].ws)
						wsets[q].flag = 1
					}
				}

				if c < NTBASE {
					state(c) // register new state
				} else {
					temp1[c-NTBASE] = state(c)
				}
			}

			if gsdebug != 0 && foutput != nil {
				fmt.Fprintf(foutput, "%v: ", i)
				for j := 0; j <= nnonter; j++ {
					if temp1[j] != 0 {
						fmt.Fprintf(foutput, "%v %v,", nontrst[j].name, temp1[j])
					}
				}
				fmt.Fprintf(foutput, "\n")
			}

			if first != 0 {
				indgo[i] = apack(temp1[1:], nnonter-1) - 1
			}

			more++
		}
	}
}

// generate the closure of state i
func closure(i int) {
	zzclose++

	// first, copy kernel of state i to wsets
	cwp = 0
	q := pstate[i+1]
	for p := pstate[i]; p < q; p++ {
		wsets[cwp].pitem = statemem[p].pitem
		wsets[cwp].flag = 1 // this item must get closed
		copy(wsets[cwp].ws, statemem[p].look)
		cwp++
	}

	// now, go through the loop, closing each item
	work := 1
	for work != 0 {
		work = 0
		for u := 0; u < cwp; u++ {
			if wsets[u].flag == 0 {
				continue
			}

			// dot is before c
			c := wsets[u].pitem.first
			if c < NTBASE {
				wsets[u].flag = 0
				// only interesting case is where . is before nonterminal
				continue
			}

			// compute the lookahead
			aryfil(clset, tbitset, 0)

			// find items involving c
			for v := u; v < cwp; v++ {
				if wsets[v].flag != 1 || wsets[v].pitem.first != c {
					continue
				}
				pi := wsets[v].pitem.prod
				ipi := wsets[v].pitem.off + 1

				wsets[v].flag = 0
				if nolook != 0 {
					continue
				}

				ch := pi[ipi]
				ipi++
				for ch > 0 {
					// terminal symbol
					if ch < NTBASE {
						setbit(clset, ch)
						break
					}

					// nonterminal symbol
					setunion(clset, pfirst[ch-NTBASE])
					if pempty[ch-NTBASE] == 0 {
						break
					}
					ch = pi[ipi]
					ipi++
				}
				if ch <= 0 {
					setunion(clset, wsets[v].ws)
				}
			}

			//
			// now loop over productions derived from c
			//
			curres := pres[c-NTBASE]
			n := len(curres)

		nexts:
			// initially fill the sets
			for s := range n {
				prd := curres[s]

				//
				// put these items into the closure
				// is the item there
				//
				for v := 0; v < cwp; v++ {
					// yes, it is there
					if wsets[v].pitem.off == 0 &&
						aryeq(wsets[v].pitem.prod, prd) != 0 {
						if nolook == 0 &&
							setunion(wsets[v].ws, clset) != 0 {
							wsets[v].flag = 1
							work = 1
						}
						continue nexts
					}
				}

				//  not there; make a new entry
				if cwp >= len(wsets) {
					awsets := make([]Wset, cwp+WSETINC)
					copy(awsets, wsets)
					wsets = awsets
				}
				wsets[cwp].pitem = Pitem{prd, 0, prd[0], -prd[len(prd)-1]}
				wsets[cwp].flag = 1
				wsets[cwp].ws = mkset()
				if nolook == 0 {
					work = 1
					copy(wsets[cwp].ws, clset)
				}
				cwp++
			}
		}
	}

	// have computed closure; flags are reset; return
	if cldebug != 0 && foutput != nil {
		fmt.Fprintf(foutput, "\nState %v, nolook = %v\n", i, nolook)
		for u := 0; u < cwp; u++ {
			if wsets[u].flag != 0 {
				fmt.Fprintf(foutput, "flag set\n")
			}
			wsets[u].flag = 0
			fmt.Fprintf(foutput, "\t%v", writem(wsets[u].pitem))
			prlook(wsets[u].ws)
			fmt.Fprintf(foutput, "\n")
		}
	}
}

// sorts last state,and sees if it equals earlier ones. returns state number
func state(c int) int {
	zzstate++
	p1 := pstate[nstate]
	p2 := pstate[nstate+1]
	if p1 == p2 {
		return 0 // null state
	}

	// sort the items
	var k, l int
	for k = p1 + 1; k < p2; k++ { // make k the biggest
		for l = k; l > p1; l-- {
			if statemem[l].pitem.prodno < statemem[l-1].pitem.prodno ||
				statemem[l].pitem.prodno == statemem[l-1].pitem.prodno &&
					statemem[l].pitem.off < statemem[l-1].pitem.off {
				s := statemem[l]
				statemem[l] = statemem[l-1]
				statemem[l-1] = s
			} else {
				break
			}
		}
	}

	size1 := p2 - p1 // size of state

	var i int
	if c >= NTBASE {
		i = ntstates[c-NTBASE]
	} else {
		i = tstates[c]
	}

look:
	for ; i != 0; i = mstates[i] {
		// get ith state
		q1 := pstate[i]
		q2 := pstate[i+1]
		size2 := q2 - q1
		if size1 != size2 {
			continue
		}
		k = p1
		for l = q1; l < q2; l++ {
			if aryeq(statemem[l].pitem.prod, statemem[k].pitem.prod) == 0 ||
				statemem[l].pitem.off != statemem[k].pitem.off {
				continue look
			}
			k++
		}

		// found it
		pstate[nstate+1] = pstate[nstate] // delete last state

		// fix up lookaheads
		if nolook != 0 {
			return i
		}
		k = p1
		for l = q1; l < q2; l++ {
			if setunion(statemem[l].look, statemem[k].look) != 0 {
				tystate[i] = MUSTDO
			}
			k++
		}
		return i
	}

	// state is new
	zznewstate++
	if nolook != 0 {
		errorf("yacc state/nolook error")
	}
	pstate[nstate+2] = p2
	if nstate+1 >= NSTATES {
		errorf("too many states")
	}
	if c >= NTBASE {
		mstates[nstate] = ntstates[c-NTBASE]
		ntstates[c-NTBASE] = nstate
	} else {
		mstates[nstate] = tstates[c]
		tstates[c] = nstate
	}
	tystate[nstate] = MUSTDO
	nstate++
	return nstate - 1
}

func putitem(p Pitem, set Lkset) {
	p.off++
	p.first = p.prod[p.off]

	if pidebug != 0 && foutput != nil {
		fmt.Fprintf(foutput, "putitem(%v), state %v\n", writem(p), nstate)
	}
	j := pstate[nstate+1]
	if j >= len(statemem) {
		asm := make([]Item, j+STATEINC)
		copy(asm, statemem)
		statemem = asm
	}
	statemem[j].pitem = p
	if nolook == 0 {
		s := mkset()
		copy(s, set)
		statemem[j].look = s
	}
	j++
	pstate[nstate+1] = j
}

// creates output string for item pointed to by pp
func writem(pp Pitem) string {
	var i int

	p := pp.prod
	var q strings.Builder
	q.WriteString(chcopy(nontrst[prdptr[pp.prodno][0]-NTBASE].name))
	q.WriteString(": ")
	npi := pp.off

	pi := aryeq(p, prdptr[pp.prodno])

	for {
		c := ' '
		if pi == npi {
			c = '.'
		}
		q.WriteByte(byte(c))

		i = p[pi]
		pi++
		if i <= 0 {
			break
		}
		q.WriteString(chcopy(symnam(i)))
	}

	// an item calling for a reduction
	i = p[npi]
	if i < 0 {
		fmt.Fprintf(&q, "    (%v)", -i)
	}

	return q.String()
}

// pack state i from temp1 into amem
func apack(p []int, n int) int {
	//
	// we don't need to worry about checking because
	// we will only look at entries known to be there...
	// eliminate leading and trailing 0's
	//
	off := 0
	pp := 0
	for ; pp <= n && p[pp] == 0; pp++ {
		off--
	}

	// no actions
	if pp > n {
		return 0
	}
	for ; n > pp && p[n] == 0; n-- {
	}
	p = p[pp : n+1]

	// now, find a place for the elements from p to q, inclusive
	r := len(amem) - len(p)

nextk:
	for rr := 0; rr <= r; rr++ {
		qq := rr
		for pp = 0; pp < len(p); pp++ {
			if p[pp] != 0 {
				if p[pp] != amem[qq] && amem[qq] != 0 {
					continue nextk
				}
			}
			qq++
		}

		// we have found an acceptable k
		if pkdebug != 0 && foutput != nil {
			fmt.Fprintf(foutput, "off = %v, k = %v\n", off+rr, rr)
		}
		qq = rr
		for pp = 0; pp < len(p); pp++ {
			if p[pp] != 0 {
				if qq > memp {
					memp = qq
				}
				amem[qq] = p[pp]
			}
			qq++
		}
		if pkdebug != 0 && foutput != nil {
			for pp = 0; pp <= memp; pp += 10 {
				fmt.Fprintf(foutput, "\n")
				for qq = pp; qq <= pp+9; qq++ {
					fmt.Fprintf(foutput, "%v ", amem[qq])
				}
				fmt.Fprintf(foutput, "\n")
			}
		}
		return off + rr
	}
	errorf("no space in action table")
	return 0
}

// print the output for the states
func output() {
	var c, u, v int

	if !lflag {
		fmt.Fprintf(ftable, "\n//line yacctab:1")
	}
	var actions []int

	if len(errors) > 0 {
		stateTable = make([]Row, nstate)
	}

	noset := mkset()

	// output the stuff for state i
	for i := 0; i < nstate; i++ {
		nolook = 0
		if tystate[i] != MUSTLOOKAHEAD {
			nolook = 1
		}
		closure(i)

		// output actions
		nolook = 1
		aryfil(temp1, ntokens+nnonter+1, 0)
		for u = 0; u < cwp; u++ {
			c = wsets[u].pitem.first
			if c > 1 && c < NTBASE && temp1[c] == 0 {
				for v = u; v < cwp; v++ {
					if c == wsets[v].pitem.first {
						putitem(wsets[v].pitem, noset)
					}
				}
				temp1[c] = state(c)
			} else if c > NTBASE {
				c -= NTBASE
				if temp1[c+ntokens] == 0 {
					temp1[c+ntokens] = amem[indgo[i]+c]
				}
			}
		}
		if i == 1 {
			temp1[1] = ACCEPTCODE
		}

		// now, we have the shifts; look at the reductions
		lastred = 0
		for u = 0; u < cwp; u++ {
			c = wsets[u].pitem.first

			// reduction
			if c > 0 {
				continue
			}
			lastred = -c
			us := wsets[u].ws
			for k := 0; k <= ntokens; k++ {
				if bitset(us, k) == 0 {
					continue
				}
				if temp1[k] == 0 {
					temp1[k] = c
				} else if temp1[k] < 0 { // reduce/reduce conflict
					if foutput != nil {
						fmt.Fprintf(foutput,
							"\n %v: reduce/reduce conflict  (red'ns "+
								"%v and %v) on %v",
							i, -temp1[k], lastred, symnam(k))
					}
					if -temp1[k] > lastred {
						temp1[k] = -lastred
					}
					zzrrconf++
				} else {
					// potential shift/reduce conflict
					precftn(lastred, k, i)
				}
			}
		}
		actions = addActions(actions, i)
	}

	arrayOutColumns("Exca", actions, 2, false)
	fmt.Fprintf(ftable, "\n")
	ftable.WriteRune('\n')
	fmt.Fprintf(ftable, "const %sPrivate = %v\n", prefix, PRIVATE)
}

// decide a shift/reduce conflict by precedence.
// r is a rule number, t a token number
// the conflict is in state s
// temp1[t] is changed to reflect the action
func precftn(r, t, s int) {
	action := NOASC

	lp := levprd[r]
	lt := toklev[t]
	if PLEVEL(lt) == 0 || PLEVEL(lp) == 0 {
		// conflict
		if foutput != nil {
			fmt.Fprintf(foutput,
				"\n%v: shift/reduce conflict (shift %v(%v), red'n %v(%v)) on %v",
				s, temp1[t], PLEVEL(lt), r, PLEVEL(lp), symnam(t))
		}
		zzsrconf++
		return
	}
	if PLEVEL(lt) == PLEVEL(lp) {
		action = ASSOC(lt)
	} else if PLEVEL(lt) > PLEVEL(lp) {
		action = RASC // shift
	} else {
		action = LASC
	} // reduce
	switch action {
	case BASC: // error action
		temp1[t] = ERRCODE
	case LASC: // reduce
		temp1[t] = -r
	}
}

// output state i
// temp1 has the actions, lastred the default
func addActions(act []int, i int) []int {
	var p, p1 int

	// find the best choice for lastred
	lastred = 0
	ntimes := 0
	for j := 0; j <= ntokens; j++ {
		if temp1[j] >= 0 {
			continue
		}
		if temp1[j]+lastred == 0 {
			continue
		}
		// count the number of appearances of temp1[j]
		count := 0
		tred := -temp1[j]
		levprd[tred] |= REDFLAG
		for p = 0; p <= ntokens; p++ {
			if temp1[p]+tred == 0 {
				count++
			}
		}
		if count > ntimes {
			lastred = tred
			ntimes = count
		}
	}

	//
	// for error recovery, arrange that, if there is a shift on the
	// error recovery token, `error', that the default be the error action
	//
	if temp1[2] > 0 {
		lastred = 0
	}

	// clear out entries in temp1 which equal lastred
	// count entries in optst table
	n := 0
	for p = 0; p <= ntokens; p++ {
		p1 = temp1[p]
		if p1+lastred == 0 {
			temp1[p] = 0
			p1 = 0
		}
		if p1 > 0 && p1 != ACCEPTCODE && p1 != ERRCODE {
			n++
		}
	}

	wrstate(i)
	defact[i] = lastred
	flag := 0
	os := make([]int, n*2)
	n = 0
	for p = 0; p <= ntokens; p++ {
		p1 = temp1[p]
		if p1 != 0 {
			if p1 < 0 {
				p1 = -p1
			} else if p1 == ACCEPTCODE {
				p1 = -1
			} else if p1 == ERRCODE {
				p1 = 0
			} else {
				os[n] = p
				n++
				os[n] = p1
				n++
				zzacent++
				continue
			}
			if flag == 0 {
				act = append(act, -1, i)
			}
			flag++
			act = append(act, p, p1)
			zzexcp++
		}
	}
	if flag != 0 {
		defact[i] = -2
		act = append(act, -2, lastred)
	}
	optst[i] = os
	return act
}

// writes state i
func wrstate(i int) {
	var j0, j1, u int
	var pp, qq int

	if len(errors) > 0 {
		actions := slices.Clone(temp1)
		defaultAction := ERRCODE
		if lastred != 0 {
			defaultAction = -lastred
		}
		stateTable[i] = Row{actions, defaultAction}
	}

	if foutput == nil {
		return
	}
	fmt.Fprintf(foutput, "\nstate %v\n", i)
	qq = pstate[i+1]
	for pp = pstate[i]; pp < qq; pp++ {
		fmt.Fprintf(foutput, "\t%v\n", writem(statemem[pp].pitem))
	}
	if tystate[i] == MUSTLOOKAHEAD {
		// print out empty productions in closure
		for u = pstate[i+1] - pstate[i]; u < cwp; u++ {
			if wsets[u].pitem.first < 0 {
				fmt.Fprintf(foutput, "\t%v\n", writem(wsets[u].pitem))
			}
		}
	}

	// check for state equal to another
	for j0 = 0; j0 <= ntokens; j0++ {
		j1 = temp1[j0]
		if j1 != 0 {
			fmt.Fprintf(foutput, "\n\t%v  ", symnam(j0))

			// shift, error, or accept
			if j1 > 0 {
				if j1 == ACCEPTCODE {
					fmt.Fprintf(foutput, "accept")
				} else if j1 == ERRCODE {
					fmt.Fprintf(foutput, "error")
				} else {
					fmt.Fprintf(foutput, "shift %v", j1)
				}
			} else {
				fmt.Fprintf(foutput, "reduce %v (src line %v)", -j1, rlines[-j1])
			}
		}
	}

	// output the final production
	if lastred != 0 {
		fmt.Fprintf(foutput, "\n\t.  reduce %v (src line %v)\n\n",
			lastred, rlines[lastred])
	} else {
		fmt.Fprintf(foutput, "\n\t.  error\n\n")
	}

	// now, output nonterminal actions
	j1 = ntokens
	for j0 = 1; j0 <= nnonter; j0++ {
		j1++
		if temp1[j1] != 0 {
			fmt.Fprintf(foutput, "\t%v  goto %v\n", symnam(j0+NTBASE), temp1[j1])
		}
	}
}

// output the gotos for the nontermninals
func go2out() {
	for i := 1; i <= nnonter; i++ {
		go2gen(i)

		// find the best one to make default
		best := -1
		times := 0

		// is j the most frequent
		for j := 0; j < nstate; j++ {
			if tystate[j] == 0 {
				continue
			}
			if tystate[j] == best {
				continue
			}

			// is tystate[j] the most frequent
			count := 0
			cbest := tystate[j]
			for k := j; k < nstate; k++ {
				if tystate[k] == cbest {
					count++
				}
			}
			if count > times {
				best = cbest
				times = count
			}
		}

		// best is now the default entry
		zzgobest += times - 1
		n := 0
		for j := 0; j < nstate; j++ {
			if tystate[j] != 0 && tystate[j] != best {
				n++
			}
		}
		goent := make([]int, 2*n+1)
		n = 0
		for j := 0; j < nstate; j++ {
			if tystate[j] != 0 && tystate[j] != best {
				goent[n] = j
				n++
				goent[n] = tystate[j]
				n++
				zzgoent++
			}
		}

		// now, the default
		if best == -1 {
			best = 0
		}

		zzgoent++
		goent[n] = best
		yypgo[i] = goent
	}
}

// output the gotos for nonterminal c
func go2gen(c int) {
	var i, cc, p, q int

	// first, find nonterminals with gotos on c
	aryfil(temp1, nnonter+1, 0)
	temp1[c] = 1
	work := 1
	for work != 0 {
		work = 0
		for i = 0; i < nprod; i++ {
			// cc is a nonterminal with a goto on c
			cc = prdptr[i][1] - NTBASE
			if cc >= 0 && temp1[cc] != 0 {
				// thus, the left side of production i does too
				cc = prdptr[i][0] - NTBASE
				if temp1[cc] == 0 {
					work = 1
					temp1[cc] = 1
				}
			}
		}
	}

	// now, we have temp1[c] = 1 if a goto on c in closure of cc
	if g2debug != 0 && foutput != nil {
		fmt.Fprintf(foutput, "%v: gotos on ", nontrst[c].name)
		for i = 0; i <= nnonter; i++ {
			if temp1[i] != 0 {
				fmt.Fprintf(foutput, "%v ", nontrst[i].name)
			}
		}
		fmt.Fprintf(foutput, "\n")
	}

	// now, go through and put gotos into tystate
	aryfil(tystate, nstate, 0)
	for i = 0; i < nstate; i++ {
		q = pstate[i+1]
		for p = pstate[i]; p < q; p++ {
			cc = statemem[p].pitem.first
			if cc >= NTBASE {
				// goto on c is possible
				if temp1[cc-NTBASE] != 0 {
					tystate[i] = amem[indgo[i]+c]
					break
				}
			}
		}
	}
}

// in order to free up the mem and amem arrays for the optimizer,
// and still be able to output yyr1, etc., after the sizes of
// the action array is known, we hide the nonterminals
// derived by productions in levprd.
func hideprod() {
	nred := 0
	levprd[0] = 0
	for i := 1; i < nprod; i++ {
		if (levprd[i] & REDFLAG) == 0 {
			if foutput != nil {
				fmt.Fprintf(foutput, "Rule not reduced: %v\n",
					writem(Pitem{prdptr[i], 0, 0, i}))
			}
			fmt.Printf("rule %v never reduced\n", writem(Pitem{prdptr[i], 0, 0, i}))
			nred++
		}
		levprd[i] = prdptr[i][0] - NTBASE
	}
	if nred != 0 {
		fmt.Printf("%v rules never reduced\n", nred)
	}
}

func callopt() {
	var j, k, p, q, i int
	var v []int

	pgo = make([]int, nnonter+1)
	pgo[0] = 0
	maxoff = 0
	maxspr = 0
	for i = 0; i < nstate; i++ {
		k = 32000
		j = 0
		v = optst[i]
		q = len(v)
		for p = 0; p < q; p += 2 {
			if v[p] > j {
				j = v[p]
			}
			if v[p] < k {
				k = v[p]
			}
		}

		// nontrivial situation
		if k <= j {
			// j is now the range
			//			j -= k;			// call scj
			if k > maxoff {
				maxoff = k
			}
		}
		tystate[i] = q + 2*j
		if j > maxspr {
			maxspr = j
		}
	}

	// initialize ggreed table
	ggreed = make([]int, nnonter+1)
	for i = 1; i <= nnonter; i++ {
		ggreed[i] = 1
		j = 0

		// minimum entry index is always 0
		v = yypgo[i]
		q = len(v) - 1
		for p = 0; p < q; p += 2 {
			ggreed[i] += 2
			if v[p] > j {
				j = v[p]
			}
		}
		ggreed[i] = ggreed[i] + 2*j
		if j > maxoff {
			maxoff = j
		}
	}

	// now, prepare to put the shift actions into the amem array
	for i = 0; i < ACTSIZE; i++ {
		amem[i] = 0
	}
	maxa = 0
	for i = 0; i < nstate; i++ {
		if tystate[i] == 0 && adb > 1 {
			fmt.Fprintf(ftable, "State %v: null\n", i)
		}
		indgo[i] = yyFlag
	}

	i = nxti()
	for i != NOMORE {
		if i >= 0 {
			stin(i)
		} else {
			gin(-i)
		}
		i = nxti()
	}

	// print amem array
	if adb > 2 {
		for p = 0; p <= maxa; p += 10 {
			fmt.Fprintf(ftable, "%v  ", p)
			for i = range 10 {
				fmt.Fprintf(ftable, "%v  ", amem[p+i])
			}
			ftable.WriteRune('\n')
		}
	}

	aoutput()
	osummary()
}

// finds the next i
func nxti() int {
	max := 0
	maxi := 0
	for i := 1; i <= nnonter; i++ {
		if ggreed[i] >= max {
			max = ggreed[i]
			maxi = -i
		}
	}
	for i := 0; i < nstate; i++ {
		if tystate[i] >= max {
			max = tystate[i]
			maxi = i
		}
	}
	if max == 0 {
		return NOMORE
	}
	return maxi
}

func gin(i int) {
	var s int

	// enter gotos on nonterminal i into array amem
	ggreed[i] = 0

	q := yypgo[i]
	nq := len(q) - 1

	// now, find amem place for it
nextgp:
	for p := range ACTSIZE {
		if amem[p] != 0 {
			continue
		}
		for r := 0; r < nq; r += 2 {
			s = p + q[r] + 1
			if s > maxa {
				maxa = s
				if maxa >= ACTSIZE {
					errorf("a array overflow")
				}
			}
			if amem[s] != 0 {
				continue nextgp
			}
		}

		// we have found amem spot
		amem[p] = q[nq]
		if p > maxa {
			maxa = p
		}
		for r := 0; r < nq; r += 2 {
			s = p + q[r] + 1
			amem[s] = q[r+1]
		}
		pgo[i] = p
		if adb > 1 {
			fmt.Fprintf(ftable, "Nonterminal %v, entry at %v\n", i, pgo[i])
		}
		return
	}
	errorf("cannot place goto %v\n", i)
}

func stin(i int) {
	var s int

	tystate[i] = 0

	// enter state i into the amem array
	q := optst[i]
	nq := len(q)

nextn:
	// find an acceptable place
	for n := -maxoff; n < ACTSIZE; n++ {
		flag := 0
		for r := 0; r < nq; r += 2 {
			s = q[r] + n
			if s < 0 || s > ACTSIZE {
				continue nextn
			}
			if amem[s] == 0 {
				flag++
			} else if amem[s] != q[r+1] {
				continue nextn
			}
		}

		// check the position equals another only if the states are identical
		for j := 0; j < nstate; j++ {
			if indgo[j] == n {

				// we have some disagreement
				if flag != 0 {
					continue nextn
				}
				if nq == len(optst[j]) {

					// states are equal
					indgo[i] = n
					if adb > 1 {
						fmt.Fprintf(ftable, "State %v: entry at"+
							"%v equals state %v\n",
							i, n, j)
					}
					return
				}

				// we have some disagreement
				continue nextn
			}
		}

		for r := 0; r < nq; r += 2 {
			s = q[r] + n
			if s > maxa {
				maxa = s
			}
			if amem[s] != 0 && amem[s] != q[r+1] {
				errorf("clobber of a array, pos'n %v, by %v", s, q[r+1])
			}
			amem[s] = q[r+1]
		}
		indgo[i] = n
		if adb > 1 {
			fmt.Fprintf(ftable, "State %v: entry at %v\n", i, indgo[i])
		}
		return
	}
	errorf("Error; failure to place state %v", i)
}

// this version is for limbo
// write out the optimized parser
func aoutput() {
	ftable.WriteRune('\n')
	fmt.Fprintf(ftable, "const %sLast = %v\n", prefix, maxa+1)
	arout("Act", amem, maxa+1)
	arout("Pact", indgo, nstate)
	arout("Pgo", pgo, nnonter+1)
}

// put out other arrays, copy the parsers
func others() {
	var i, j int

	arout("R1", levprd, nprod)
	aryfil(temp1, nprod, 0)

	//
	//yyr2 is the number of rules for each production
	//
	for i = 1; i < nprod; i++ {
		temp1[i] = len(prdptr[i]) - 2
	}
	arout("R2", temp1, nprod)

	aryfil(temp1, nstate, -1000)
	for i = 0; i <= ntokens; i++ {
		for j := tstates[i]; j != 0; j = mstates[j] {
			temp1[j] = i
		}
	}
	for i = 0; i <= nnonter; i++ {
		for j = ntstates[i]; j != 0; j = mstates[j] {
			temp1[j] = -i
		}
	}
	arout("Chk", temp1, nstate)
	arrayOutColumns("Def", defact[:nstate], 10, false)

	// put out token translation tables
	// table 1 has 0-256
	aryfil(temp1, 256, 0)
	c := 0
	for i = 1; i <= ntokens; i++ {
		j = tokset[i].value
		if j >= 0 && j < 256 {
			if temp1[j] != 0 {
				fmt.Print("yacc bug -- cannot have 2 different Ts with same value\n")
				fmt.Printf("	%s and %s\n", tokset[i].name, tokset[temp1[j]].name)
				nerrors++
			}
			temp1[j] = i
			if j > c {
				c = j
			}
		}
	}
	for i = 0; i <= c; i++ {
		if temp1[i] == 0 {
			temp1[i] = YYLEXUNK
		}
	}
	arout("Tok1", temp1, c+1)

	// table 2 has PRIVATE-PRIVATE+256
	aryfil(temp1, 256, 0)
	c = 0
	for i = 1; i <= ntokens; i++ {
		j = tokset[i].value - PRIVATE
		if j >= 0 && j < 256 {
			if temp1[j] != 0 {
				fmt.Print("yacc bug -- cannot have 2 different Ts with same value\n")
				fmt.Printf("	%s and %s\n", tokset[i].name, tokset[temp1[j]].name)
				nerrors++
			}
			temp1[j] = i
			if j > c {
				c = j
			}
		}
	}
	arout("Tok2", temp1, c+1)

	// table 3 has everything else
	ftable.WriteRune('\n')
	var v []int
	for i = 1; i <= ntokens; i++ {
		j = tokset[i].value
		if j >= 0 && j < 256 {
			continue
		}
		if j >= PRIVATE && j < 256+PRIVATE {
			continue
		}

		v = append(v, j, i)
	}
	v = append(v, 0)
	arout("Tok3", v, len(v))
	fmt.Fprintf(ftable, "\n")

	// Custom error messages.
	fmt.Fprintf(ftable, "\n")
	fmt.Fprintf(ftable, "var %sErrorMessages = [...]struct {\n", prefix)
	fmt.Fprintf(ftable, "\tstate int\n")
	fmt.Fprintf(ftable, "\ttoken int\n")
	fmt.Fprintf(ftable, "\tmsg   string\n")
	fmt.Fprintf(ftable, "}{\n")
	for _, error := range errors {
		lineno = error.lineno
		state, token := runMachine(error.tokens)
		fmt.Fprintf(ftable, "\t{%v, %v, %s},\n", state, token, error.msg)
	}
	fmt.Fprintf(ftable, "}\n")

	// copy parser text
	ch := getrune(finput)
	for ch != EOF {
		ftable.WriteRune(ch)
		ch = getrune(finput)
	}

	// copy yaccpar
	if !lflag {
		fmt.Fprintf(ftable, "\n//line yaccpar:1\n")
	}

	parts := strings.SplitN(yaccpar, prefix+"run()", 2)
	fmt.Fprintf(ftable, "%v", parts[0])
	ftable.Write(fcode.Bytes())
	fmt.Fprintf(ftable, "%v", parts[1])
}

func runMachine(tokens []string) (state, token int) {
	var stack []int
	i := 0
	token = -1

Loop:
	if token < 0 {
		token = chfind(2, tokens[i])
		i++
	}

	row := stateTable[state]

	c := token
	if token >= NTBASE {
		c = token - NTBASE + ntokens
	}
	action := row.actions[c]
	if action == 0 {
		action = row.defaultAction
	}

	switch {
	case action == ACCEPTCODE:
		errorf("tokens are accepted")
		return
	case action == ERRCODE:
		if token >= NTBASE {
			errorf("error at non-terminal token %s", symnam(token))
		}
		return
	case action > 0:
		// Shift to state action.
		stack = append(stack, state)
		state = action
		token = -1
		goto Loop
	default:
		// Reduce by production -action.
		prod := prdptr[-action]
		if rhsLen := len(prod) - 2; rhsLen > 0 {
			n := len(stack) - rhsLen
			state = stack[n]
			stack = stack[:n]
		}
		if token >= 0 {
			i--
		}
		token = prod[0]
		goto Loop
	}
}

func minMax(v []int) (min, max int) {
	if len(v) == 0 {
		return
	}
	min = v[0]
	max = v[0]
	for _, i := range v {
		if i < min {
			min = i
		}
		if i > max {
			max = i
		}
	}
	return
}

// return the smaller integral base type to store the values in v
func minType(v []int, allowUnsigned bool) (typ string) {
	typ = "int"
	typeLen := 8
	min, max := minMax(v)
	checkType := func(name string, size, minType, maxType int) {
		if min >= minType && max <= maxType && typeLen > size {
			typ = name
			typeLen = size
		}
	}
	checkType("int32", 4, math.MinInt32, math.MaxInt32)
	checkType("int16", 2, math.MinInt16, math.MaxInt16)
	checkType("int8", 1, math.MinInt8, math.MaxInt8)
	if allowUnsigned {
		// Do not check for uint32, not worth and won't compile on 32 bit systems
		checkType("uint16", 2, 0, math.MaxUint16)
		checkType("uint8", 1, 0, math.MaxUint8)
	}
	return
}

func arrayOutColumns(s string, v []int, columns int, allowUnsigned bool) {
	s = prefix + s
	ftable.WriteRune('\n')
	minType := minType(v, allowUnsigned)
	fmt.Fprintf(ftable, "var %v = [...]%s{", s, minType)
	for i, val := range v {
		if i%columns == 0 {
			fmt.Fprintf(ftable, "\n\t")
		} else {
			ftable.WriteRune(' ')
		}
		fmt.Fprintf(ftable, "%d,", val)
	}
	fmt.Fprintf(ftable, "\n}\n")
}

func arout(s string, v []int, n int) {
	arrayOutColumns(s, v[:n], 10, true)
}

// output the summary on y.output
func summary() {
	if foutput != nil {
		fmt.Fprintf(foutput, "\n%v terminals, %v nonterminals\n", ntokens, nnonter+1)
		fmt.Fprintf(foutput, "%v grammar rules, %v/%v states\n", nprod, nstate, NSTATES)
		fmt.Fprintf(foutput, "%v shift/reduce, %v reduce/reduce conflicts reported\n", zzsrconf, zzrrconf)
		fmt.Fprintf(foutput, "%v working sets used\n", len(wsets))
		fmt.Fprintf(foutput, "memory: parser %v/%v\n", memp, ACTSIZE)
		fmt.Fprintf(foutput, "%v extra closures\n", zzclose-2*nstate)
		fmt.Fprintf(foutput, "%v shift entries, %v exceptions\n", zzacent, zzexcp)
		fmt.Fprintf(foutput, "%v goto entries\n", zzgoent)
		fmt.Fprintf(foutput, "%v entries saved by goto default\n", zzgobest)
	}
	if zzsrconf != 0 || zzrrconf != 0 {
		fmt.Printf("\nconflicts: ")
		if zzsrconf != 0 {
			fmt.Printf("%v shift/reduce", zzsrconf)
		}
		if zzsrconf != 0 && zzrrconf != 0 {
			fmt.Printf(", ")
		}
		if zzrrconf != 0 {
			fmt.Printf("%v reduce/reduce", zzrrconf)
		}
		fmt.Printf("\n")
	}
}

// write optimizer summary
func osummary() {
	if foutput == nil {
		return
	}
	i := 0
	for p := maxa; p >= 0; p-- {
		if amem[p] == 0 {
			i++
		}
	}

	fmt.Fprintf(foutput, "Optimizer space used: output %v/%v\n", maxa+1, ACTSIZE)
	fmt.Fprintf(foutput, "%v table entries, %v zero\n", maxa+1, i)
	fmt.Fprintf(foutput, "maximum spread: %v, maximum offset: %v\n", maxspr, maxoff)
}

// copies and protects "'s in q
func chcopy(q string) string {
	var s strings.Builder
	i := 0
	j := 0
	for i = 0; i < len(q); i++ {
		if q[i] == '"' {
			s.WriteString(q[j:i])
			s.WriteByte('\\')
			j = i
		}
	}
	s.WriteString(q[j:i])
	return s.String()
}

func usage() {
	fmt.Fprintf(stderr, "usage: yacc [-o output] [-v parsetable] input\n")
	exit(1)
}

func bitset(set Lkset, bit int) int { return set[bit>>5] & (1 << uint(bit&31)) }

func setbit(set Lkset, bit int) { set[bit>>5] |= (1 << uint(bit&31)) }

func mkset() Lkset { return make([]int, tbitset) }

// set a to the union of a and b
// return 1 if b is not a subset of a, 0 otherwise
func setunion(a, b []int) int {
	sub := 0
	for i := 0; i < tbitset; i++ {
		x := a[i]
		y := x | b[i]
		a[i] = y
		if y != x {
			sub = 1
		}
	}
	return sub
}

func prlook(p Lkset) {
	if p == nil {
		fmt.Fprintf(foutput, "\tNULL")
		return
	}
	fmt.Fprintf(foutput, " { ")
	for j := 0; j <= ntokens; j++ {
		if bitset(p, j) != 0 {
			fmt.Fprintf(foutput, "%v ", symnam(j))
		}
	}
	fmt.Fprintf(foutput, "}")
}

// utility routines
var peekrune rune

func isdigit(c rune) bool { return c >= '0' && c <= '9' }

func isword(c rune) bool {
	return c >= 0xa0 || c == '_' || (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')
}

// return 1 if 2 arrays are equal
// return 0 if not equal
func aryeq(a []int, b []int) int {
	n := len(a)
	if len(b) != n {
		return 0
	}
	for ll := range n {
		if a[ll] != b[ll] {
			return 0
		}
	}
	return 1
}

func getrune(f *bufio.Reader) rune {
	var r rune

	if peekrune != 0 {
		if peekrune == EOF {
			return EOF
		}
		r = peekrune
		peekrune = 0
		return r
	}

	c, n, err := f.ReadRune()
	if n == 0 {
		return EOF
	}
	if err != nil {
		errorf("read error: %v", err)
	}
	//fmt.Printf("rune = %v n=%v\n", string(c), n);
	return c
}

func ungetrune(f *bufio.Reader, c rune) {
	if f != finput {
		panic("ungetc - not finput")
	}
	if peekrune != 0 {
		panic("ungetc - 2nd unget")
	}
	peekrune = c
}

func open(s string) *bufio.Reader {
	fi, err := os.Open(s)
	if err != nil {
		errorf("error opening %v: %v", s, err)
	}
	//fmt.Printf("open %v\n", s);
	return bufio.NewReader(fi)
}

func create(s string) *bufio.Writer {
	fo, err := os.Create(s)
	if err != nil {
		errorf("error creating %v: %v", s, err)
	}
	//fmt.Printf("create %v mode %v\n", s);
	return bufio.NewWriter(fo)
}

// write out error comment
func lerrorf(lineno int, s string, v ...any) {
	nerrors++
	fmt.Fprintf(stderr, s, v...)
	fmt.Fprintf(stderr, ": %v:%v\n", infile, lineno)
	if fatfl != 0 {
		summary()
		exit(1)
	}
}

func errorf(s string, v ...any) {
	lerrorf(lineno, s, v...)
}

func exit(status int) {
	if ftable != nil {
		ftable.Flush()
		ftable = nil
		gofmt()
	}
	if foutput != nil {
		foutput.Flush()
		foutput = nil
	}
	if stderr != nil {
		stderr.Flush()
		stderr = nil
	}
	os.Exit(status)
}

func gofmt() {
	src, err := os.ReadFile(oflag)
	if err != nil {
		return
	}
	src, err = format.Source(src)
	if err != nil {
		return
	}
	os.WriteFile(oflag, src, 0666)
}

var yaccpar string // will be processed version of yaccpartext: s/$$/prefix/g
var yaccpartext = `
/*	parser for yacc output	*/

var (
	$$Debug        = 0
	$$ErrorVerbose = false
)

type $$Lexer interface {
	Lex(lval *$$SymType) int
	Error(s string)
}

type $$Parser interface {
	Parse($$Lexer) int
	Lookahead() int
}

type $$ParserImpl struct {
	lval  $$SymType
	stack [$$InitialStackSize]$$SymType
	char  int
}

func (p *$$ParserImpl) Lookahead() int {
	return p.char
}

func $$NewParser() $$Parser {
	return &$$ParserImpl{}
}

const $$Flag = -1000

func $$Tokname(c int) string {
	if c >= 1 && c-1 < len($$Toknames) {
		if $$Toknames[c-1] != "" {
			return $$Toknames[c-1]
		}
	}
	return __yyfmt__.Sprintf("tok-%v", c)
}

func $$Statname(s int) string {
	if s >= 0 && s < len($$Statenames) {
		if $$Statenames[s] != "" {
			return $$Statenames[s]
		}
	}
	return __yyfmt__.Sprintf("state-%v", s)
}

func $$ErrorMessage(state, lookAhead int) string {
	const TOKSTART = 4

	if !$$ErrorVerbose {
		return "syntax error"
	}

	for _, e := range $$ErrorMessages {
		if e.state == state && e.token == lookAhead {
			return "syntax error: " + e.msg
		}
	}

	res := "syntax error: unexpected " + $$Tokname(lookAhead)

	// To match Bison, suggest at most four expected tokens.
	expected := make([]int, 0, 4)

	// Look for shiftable tokens.
	base := int($$Pact[state])
	for tok := TOKSTART; tok-1 < len($$Toknames); tok++ {
		if n := base + tok; n >= 0 && n < $$Last && int($$Chk[int($$Act[n])]) == tok {
			if len(expected) == cap(expected) {
				return res
			}
			expected = append(expected, tok)
		}
	}

	if $$Def[state] == -2 {
		i := 0
		for $$Exca[i] != -1 || int($$Exca[i+1]) != state {
			i += 2
		}

		// Look for tokens that we accept or reduce.
		for i += 2; $$Exca[i] >= 0; i += 2 {
			tok := int($$Exca[i])
			if tok < TOKSTART || $$Exca[i+1] == 0 {
				continue
			}
			if len(expected) == cap(expected) {
				return res
			}
			expected = append(expected, tok)
		}

		// If the default action is to accept or reduce, give up.
		if $$Exca[i+1] != 0 {
			return res
		}
	}

	for i, tok := range expected {
		if i == 0 {
			res += ", expecting "
		} else {
			res += " or "
		}
		res += $$Tokname(tok)
	}
	return res
}

func $$lex1(lex $$Lexer, lval *$$SymType) (char, token int) {
	token = 0
	char = lex.Lex(lval)
	if char <= 0 {
		token = int($$Tok1[0])
		goto out
	}
	if char < len($$Tok1) {
		token = int($$Tok1[char])
		goto out
	}
	if char >= $$Private {
		if char < $$Private+len($$Tok2) {
			token = int($$Tok2[char-$$Private])
			goto out
		}
	}
	for i := 0; i < len($$Tok3); i += 2 {
		token = int($$Tok3[i+0])
		if token == char {
			token = int($$Tok3[i+1])
			goto out
		}
	}

out:
	if token == 0 {
		token = int($$Tok2[1]) /* unknown char */
	}
	if $$Debug >= 3 {
		__yyfmt__.Printf("lex %s(%d)\n", $$Tokname(token), uint(char))
	}
	return char, token
}

func $$Parse($$lex $$Lexer) int {
	return $$NewParser().Parse($$lex)
}

func ($$rcvr *$$ParserImpl) Parse($$lex $$Lexer) int {
	var $$n int
	var $$VAL $$SymType
	var $$Dollar []$$SymType
	_ = $$Dollar // silence set and not used
	$$S := $$rcvr.stack[:]

	Nerrs := 0   /* number of errors */
	Errflag := 0 /* error recovery flag */
	$$state := 0
	$$rcvr.char = -1
	$$token := -1 // $$rcvr.char translated into internal numbering
	defer func() {
		// Make sure we report no lookahead when not parsing.
		$$state = -1
		$$rcvr.char = -1
		$$token = -1
	}()
	$$p := -1
	goto $$stack

ret0:
	return 0

ret1:
	return 1

$$stack:
	/* put a state and value onto the stack */
	if $$Debug >= 4 {
		__yyfmt__.Printf("char %v in %v\n", $$Tokname($$token), $$Statname($$state))
	}

	$$p++
	if $$p >= len($$S) {
		nyys := make([]$$SymType, len($$S)*2)
		copy(nyys, $$S)
		$$S = nyys
	}
	$$S[$$p] = $$VAL
	$$S[$$p].yys = $$state

$$newstate:
	$$n = int($$Pact[$$state])
	if $$n <= $$Flag {
		goto $$default /* simple state */
	}
	if $$rcvr.char < 0 {
		$$rcvr.char, $$token = $$lex1($$lex, &$$rcvr.lval)
	}
	$$n += $$token
	if $$n < 0 || $$n >= $$Last {
		goto $$default
	}
	$$n = int($$Act[$$n])
	if int($$Chk[$$n]) == $$token { /* valid shift */
		$$rcvr.char = -1
		$$token = -1
		$$VAL = $$rcvr.lval
		$$state = $$n
		if Errflag > 0 {
			Errflag--
		}
		goto $$stack
	}

$$default:
	/* default state action */
	$$n = int($$Def[$$state])
	if $$n == -2 {
		if $$rcvr.char < 0 {
			$$rcvr.char, $$token = $$lex1($$lex, &$$rcvr.lval)
		}

		/* look through exception table */
		xi := 0
		for {
			if $$Exca[xi+0] == -1 && int($$Exca[xi+1]) == $$state {
				break
			}
			xi += 2
		}
		for xi += 2; ; xi += 2 {
			$$n = int($$Exca[xi+0])
			if $$n < 0 || $$n == $$token {
				break
			}
		}
		$$n = int($$Exca[xi+1])
		if $$n < 0 {
			goto ret0
		}
	}
	if $$n == 0 {
		/* error ... attempt to resume parsing */
		switch Errflag {
		case 0: /* brand new error */
			$$lex.Error($$ErrorMessage($$state, $$token))
			Nerrs++
			if $$Debug >= 1 {
				__yyfmt__.Printf("%s", $$Statname($$state))
				__yyfmt__.Printf(" saw %s\n", $$Tokname($$token))
			}
			fallthrough

		case 1, 2: /* incompletely recovered error ... try again */
			Errflag = 3

			/* find a state where "error" is a legal shift action */
			for $$p >= 0 {
				$$n = int($$Pact[$$S[$$p].yys]) + $$ErrCode
				if $$n >= 0 && $$n < $$Last {
					$$state = int($$Act[$$n]) /* simulate a shift of "error" */
					if int($$Chk[$$state]) == $$ErrCode {
						goto $$stack
					}
				}

				/* the current p has no shift on "error", pop stack */
				if $$Debug >= 2 {
					__yyfmt__.Printf("error recovery pops state %d\n", $$S[$$p].yys)
				}
				$$p--
			}
			/* there is no state on the stack with an error shift ... abort */
			goto ret1

		case 3: /* no shift yet; clobber input char */
			if $$Debug >= 2 {
				__yyfmt__.Printf("error recovery discards %s\n", $$Tokname($$token))
			}
			if $$token == $$EofCode {
				goto ret1
			}
			$$rcvr.char = -1
			$$token = -1
			goto $$newstate /* try again in the same state */
		}
	}

	/* reduction by production $$n */
	if $$Debug >= 2 {
		__yyfmt__.Printf("reduce %v in:\n\t%v\n", $$n, $$Statname($$state))
	}

	$$nt := $$n
	$$pt := $$p
	_ = $$pt // guard against "declared and not used"

	$$p -= int($$R2[$$n])
	// $$p is now the index of $0. Perform the default action. Iff the
	// reduced production is ε, $1 is possibly out of range.
	if $$p+1 >= len($$S) {
		nyys := make([]$$SymType, len($$S)*2)
		copy(nyys, $$S)
		$$S = nyys
	}
	$$VAL = $$S[$$p+1]

	/* consult goto table to find next state */
	$$n = int($$R1[$$n])
	$$g := int($$Pgo[$$n])
	$$j := $$g + $$S[$$p].yys + 1

	if $$j >= $$Last {
		$$state = int($$Act[$$g])
	} else {
		$$state = int($$Act[$$j])
		if int($$Chk[$$state]) != -$$n {
			$$state = int($$Act[$$g])
		}
	}
	// dummy call; replaced with literal code
	$$run()
	goto $$stack /* stack new state and value */
}
`


================================================
FILE: cmd/html2article/conv.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This program takes an HTML file and outputs a corresponding article file in
// present format. See: golang.org/x/tools/present
package main // import "golang.org/x/tools/cmd/html2article"

import (
	"bytes"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"net/url"
	"os"
	"regexp"
	"slices"
	"strings"

	"golang.org/x/net/html"
	"golang.org/x/net/html/atom"
)

func main() {
	flag.Parse()

	err := convert(os.Stdout, os.Stdin)
	if err != nil {
		log.Fatal(err)
	}
}

func convert(w io.Writer, r io.Reader) error {
	root, err := html.Parse(r)
	if err != nil {
		return err
	}

	style := find(root, isTag(atom.Style))
	if err := parseStyles(style); err != nil {
		log.Printf("couldn't parse all styles: %v", err)
	}

	body := find(root, isTag(atom.Body))
	if body == nil {
		return errors.New("couldn't find body")
	}
	article := limitNewlineRuns(makeHeadings(strings.TrimSpace(text(body))))
	_, err = fmt.Fprintf(w, "Title\n\n%s", article)
	return err
}

type Style string

const (
	Bold   Style = "*"
	Italic Style = "_"
	Code   Style = "`"
)

var cssRules = make(map[string]Style)

func parseStyles(style *html.Node) error {
	if style == nil || style.FirstChild == nil {
		return errors.New("couldn't find styles")
	}

	styles := style.FirstChild.Data
	readUntil := func(end rune) (string, bool) {
		i := strings.IndexRune(styles, end)
		if i < 0 {
			return "", false
		}
		s := styles[:i]
		styles = styles[i:]
		return s, true
	}

	for {
		sel, ok := readUntil('{')
		if !ok && sel == "" {
			break
		} else if !ok {
			return fmt.Errorf("could not parse selector %q", styles)
		}

		value, ok := readUntil('}')
		if !ok {
			return fmt.Errorf("couldn't parse style body for %s", sel)
		}
		switch {
		case strings.Contains(value, "italic"):
			cssRules[sel] = Italic
		case strings.Contains(value, "bold"):
			cssRules[sel] = Bold
		case strings.Contains(value, "Consolas") || strings.Contains(value, "Courier New"):
			cssRules[sel] = Code
		}
	}
	return nil
}

var newlineRun = regexp.MustCompile(`\n\n+`)

func limitNewlineRuns(s string) string {
	return newlineRun.ReplaceAllString(s, "\n\n")
}

func makeHeadings(body string) string {
	buf := new(bytes.Buffer)
	lines := strings.Split(body, "\n")
	for i, s := range lines {
		if i == 0 && !isBoldTitle(s) {
			buf.WriteString("* Introduction\n\n")
		}
		if isBoldTitle(s) {
			s = strings.TrimSpace(strings.Replace(s, "*", " ", -1))
			s = "* " + s
		}
		buf.WriteString(s)
		buf.WriteByte('\n')
	}
	return buf.String()
}

func isBoldTitle(s string) bool {
	return !strings.Contains(s, " ") &&
		strings.HasPrefix(s, "*") &&
		strings.HasSuffix(s, "*")
}

func indent(buf *bytes.Buffer, s string) {
	for l := range strings.SplitSeq(s, "\n") {
		if l != "" {
			buf.WriteByte('\t')
			buf.WriteString(l)
		}
		buf.WriteByte('\n')
	}
}

func unwrap(buf *bytes.Buffer, s string) {
	var cont bool
	for l := range strings.SplitSeq(s, "\n") {
		l = strings.TrimSpace(l)
		if len(l) == 0 {
			if cont {
				buf.WriteByte('\n')
				buf.WriteByte('\n')
			}
			cont = false
		} else {
			if cont {
				buf.WriteByte(' ')
			}
			buf.WriteString(l)
			cont = true
		}
	}
}

func text(n *html.Node) string {
	var buf bytes.Buffer
	walk(n, func(n *html.Node) bool {
		switch n.Type {
		case html.TextNode:
			buf.WriteString(n.Data)
			return false
		case html.ElementNode:
			// no-op
		default:
			return true
		}
		a := n.DataAtom
		if a == atom.Span {
			switch {
			case hasStyle(Code)(n):
				a = atom.Code
			case hasStyle(Bold)(n):
				a = atom.B
			case hasStyle(Italic)(n):
				a = atom.I
			}
		}
		switch a {
		case atom.Br:
			buf.WriteByte('\n')
		case atom.P:
			unwrap(&buf, childText(n))
			buf.WriteString("\n\n")
		case atom.Li:
			buf.WriteString("- ")
			unwrap(&buf, childText(n))
			buf.WriteByte('\n')
		case atom.Pre:
			indent(&buf, childText(n))
			buf.WriteByte('\n')
		case atom.A:
			href, text := attr(n, "href"), childText(n)
			// Skip links with no text.
			if strings.TrimSpace(text) == "" {
				break
			}
			// Don't emit empty links.
			if strings.TrimSpace(href) == "" {
				buf.WriteString(text)
				break
			}
			// Use original url for Google Docs redirections.
			if u, err := url.Parse(href); err != nil {
				log.Printf("parsing url %q: %v", href, err)
			} else if u.Host == "www.google.com" && u.Path == "/url" {
				href = u.Query().Get("q")
			}
			fmt.Fprintf(&buf, "[[%s][%s]]", href, text)
		case atom.Code:
			buf.WriteString(highlight(n, "`"))
		case atom.B:
			buf.WriteString(highlight(n, "*"))
		case atom.I:
			buf.WriteString(highlight(n, "_"))
		case atom.Img:
			src := attr(n, "src")
			fmt.Fprintf(&buf, ".image %s\n", src)
		case atom.Iframe:
			src, w, h := attr(n, "src"), attr(n, "width"), attr(n, "height")
			fmt.Fprintf(&buf, "\n.iframe %s %s %s\n", src, h, w)
		case atom.Param:
			if attr(n, "name") == "movie" {
				// Old style YouTube embed.
				u := attr(n, "value")
				u = strings.Replace(u, "/v/", "/embed/", 1)
				if i := strings.Index(u, "&"); i >= 0 {
					u = u[:i]
				}
				fmt.Fprintf(&buf, "\n.iframe %s 540 304\n", u)
			}
		case atom.Title:
		default:
			return true
		}
		return false
	})
	return buf.String()
}

func childText(node *html.Node) string {
	var buf bytes.Buffer
	for n := node.FirstChild; n != nil; n = n.NextSibling {
		fmt.Fprint(&buf, text(n))
	}
	return buf.String()
}

func highlight(node *html.Node, char string) string {
	t := strings.Replace(childText(node), " ", char, -1)
	return fmt.Sprintf("%s%s%s", char, t, char)
}

type selector func(*html.Node) bool

func isTag(a atom.Atom) selector {
	return func(n *html.Node) bool {
		return n.DataAtom == a
	}
}

func hasClass(name string) selector {
	return func(n *html.Node) bool {
		for _, a := range n.Attr {
			if a.Key == "class" {
				if slices.Contains(strings.Fields(a.Val), name) {
					return true
				}
			}
		}
		return false
	}
}

func hasStyle(s Style) selector {
	return func(n *html.Node) bool {
		for rule, s2 := range cssRules {
			if s2 != s {
				continue
			}
			if strings.HasPrefix(rule, ".") && hasClass(rule[1:])(n) {
				return true
			}
			if n.DataAtom.String() == rule {
				return true
			}
		}
		return false
	}
}

func attr(node *html.Node, key string) (value string) {
	for _, attr := range node.Attr {
		if attr.Key == key {
			return attr.Val
		}
	}
	return ""
}

func find(n *html.Node, fn selector) *html.Node {
	var result *html.Node
	walk(n, func(n *html.Node) bool {
		if result != nil {
			return false
		}
		if fn(n) {
			result = n
			return false
		}
		return true
	})
	return result
}

func walk(n *html.Node, fn selector) {
	if fn(n) {
		for c := n.FirstChild; c != nil; c = c.NextSibling {
			walk(c, fn)
		}
	}
}


================================================
FILE: cmd/present/dir.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"html/template"
	"io"
	"io/fs"
	"log"
	"net"
	"net/http"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"golang.org/x/tools/present"
)

func init() {
	http.HandleFunc("/", dirHandler)
}

// dirHandler serves a directory listing for the requested path, rooted at *contentPath.
func dirHandler(w http.ResponseWriter, r *http.Request) {
	if r.URL.Path == "/favicon.ico" {
		http.NotFound(w, r)
		return
	}
	name := filepath.Join(*contentPath, r.URL.Path)
	if isDoc(name) {
		err := renderDoc(w, name)
		if err != nil {
			log.Println(err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
		return
	}
	if isDir, err := dirList(w, name); err != nil {
		addr, _, e := net.SplitHostPort(r.RemoteAddr)
		if e != nil {
			addr = r.RemoteAddr
		}
		log.Printf("request from %s: %s", addr, err)
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	} else if isDir {
		return
	}
	http.FileServer(http.Dir(*contentPath)).ServeHTTP(w, r)
}

func isDoc(path string) bool {
	_, ok := contentTemplate[filepath.Ext(path)]
	return ok
}

var (
	// dirListTemplate holds the front page template.
	dirListTemplate *template.Template

	// contentTemplate maps the presentable file extensions to the
	// template to be executed.
	contentTemplate map[string]*template.Template
)

func initTemplates(fsys fs.FS) error {
	// Locate the template file.
	actionTmpl := "templates/action.tmpl"

	contentTemplate = make(map[string]*template.Template)

	for ext, contentTmpl := range map[string]string{
		".slide":   "slides.tmpl",
		".article": "article.tmpl",
	} {
		contentTmpl = "templates/" + contentTmpl

		// Read and parse the input.
		tmpl := present.Template()
		tmpl = tmpl.Funcs(template.FuncMap{"playable": playable})
		if _, err := tmpl.ParseFS(fsys, actionTmpl, contentTmpl); err != nil {
			return err
		}
		contentTemplate[ext] = tmpl
	}

	var err error
	dirListTemplate, err = template.ParseFS(fsys, "templates/dir.tmpl")
	return err
}

// renderDoc reads the present file, gets its template representation,
// and executes the template, sending output to w.
func renderDoc(w io.Writer, docFile string) error {
	// Read the input and build the doc structure.
	doc, err := parse(docFile, 0)
	if err != nil {
		return err
	}

	// Find which template should be executed.
	tmpl := contentTemplate[filepath.Ext(docFile)]

	// Execute the template.
	return doc.Render(w, tmpl)
}

func parse(name string, mode present.ParseMode) (*present.Doc, error) {
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	return present.Parse(f, name, mode)
}

// dirList scans the given path and writes a directory listing to w.
// It parses the first part of each .slide file it encounters to display the
// presentation title in the listing.
// If the given path is not a directory, it returns (isDir == false, err == nil)
// and writes nothing to w.
func dirList(w io.Writer, name string) (isDir bool, err error) {
	f, err := os.Open(name)
	if err != nil {
		return false, err
	}
	defer f.Close()
	fi, err := f.Stat()
	if err != nil {
		return false, err
	}
	if isDir = fi.IsDir(); !isDir {
		return false, nil
	}
	fis, err := f.Readdir(0)
	if err != nil {
		return false, err
	}
	strippedPath := strings.TrimPrefix(name, filepath.Clean(*contentPath))
	strippedPath = strings.TrimPrefix(strippedPath, "/")
	d := &dirListData{Path: strippedPath}
	for _, fi := range fis {
		// skip the golang.org directory
		if name == "." && fi.Name() == "golang.org" {
			continue
		}
		e := dirEntry{
			Name: fi.Name(),
			Path: filepath.ToSlash(filepath.Join(strippedPath, fi.Name())),
		}
		if fi.IsDir() && showDir(e.Name) {
			d.Dirs = append(d.Dirs, e)
			continue
		}
		if isDoc(e.Name) {
			fn := filepath.ToSlash(filepath.Join(name, fi.Name()))
			if p, err := parse(fn, present.TitlesOnly); err != nil {
				log.Printf("parse(%q, present.TitlesOnly): %v", fn, err)
			} else {
				e.Title = p.Title
			}
			switch filepath.Ext(e.Path) {
			case ".article":
				d.Articles = append(d.Articles, e)
			case ".slide":
				d.Slides = append(d.Slides, e)
			}
		} else if showFile(e.Name) {
			d.Other = append(d.Other, e)
		}
	}
	if d.Path == "." {
		d.Path = ""
	}
	sort.Sort(d.Dirs)
	sort.Sort(d.Slides)
	sort.Sort(d.Articles)
	sort.Sort(d.Other)
	return true, dirListTemplate.Execute(w, d)
}

// showFile reports whether the given file should be displayed in the list.
func showFile(n string) bool {
	switch filepath.Ext(n) {
	case ".pdf":
	case ".html":
	case ".go":
	default:
		return isDoc(n)
	}
	return true
}

// showDir reports whether the given directory should be displayed in the list.
func showDir(n string) bool {
	if len(n) > 0 && (n[0] == '.' || n[0] == '_') || n == "present" {
		return false
	}
	return true
}

type dirListData struct {
	Path                          string
	Dirs, Slides, Articles, Other dirEntrySlice
}

type dirEntry struct {
	Name, Path, Title string
}

type dirEntrySlice []dirEntry

func (s dirEntrySlice) Len() int           { return len(s) }
func (s dirEntrySlice) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
func (s dirEntrySlice) Less(i, j int) bool { return s[i].Name < s[j].Name }


================================================
FILE: cmd/present/doc.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Present displays slide presentations and articles. It runs a web server that
presents slide and article files from the current directory.

It may be run as a stand-alone command or an App Engine app.

To use with App Engine, copy the files in the tools/cmd/present directory to the
root of your application and create an app.yaml file similar to this:

	runtime: go111

	handlers:
	- url: /favicon.ico
	  static_files: static/favicon.ico
	  upload: static/favicon.ico
	- url: /static
	  static_dir: static
	- url: /.*
	  script: auto

	# nobuild_files is a regexp that identifies which files to not build.  It
	# is useful for embedding static assets like code snippets and preventing
	# them from producing build errors for your project.
	nobuild_files: [path regexp for talk materials]

When running on App Engine, content will be served from the ./content/
subdirectory.

Present then can be tested in a local App Engine environment with

	GAE_ENV=standard go run .

And deployed using

	gcloud app deploy

Input files are named foo.extension, where "extension" defines the format of
the generated output. The supported formats are:

	.slide        // HTML5 slide presentation
	.article      // article format, such as a blog post

The present file format is documented by the present package:
https://pkg.go.dev/golang.org/x/tools/present
*/
package main


================================================
FILE: cmd/present/main.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"embed"
	"flag"
	"fmt"
	"io/fs"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"strings"

	"golang.org/x/tools/present"
)

var (
	httpAddr      = flag.String("http", "127.0.0.1:3999", "HTTP service address (e.g., '127.0.0.1:3999')")
	originHost    = flag.String("orighost", "", "host component of web origin URL (e.g., 'localhost')")
	basePath      = flag.String("base", "", "base path for slide template and static resources")
	contentPath   = flag.String("content", ".", "base path for presentation content")
	usePlayground = flag.Bool("use_playground", false, "run code snippets using play.golang.org; if false, run them locally and deliver results by WebSocket transport")
)

//go:embed static templates
var embedFS embed.FS

func main() {
	flag.BoolVar(&present.PlayEnabled, "play", true, "enable playground (permit execution of arbitrary user code)")
	flag.BoolVar(&present.NotesEnabled, "notes", false, "enable presenter notes (press 'N' from the browser to display them)")
	flag.Parse()

	if os.Getenv("GAE_ENV") == "standard" {
		log.Print("Configuring for App Engine Standard")
		port := os.Getenv("PORT")
		if port == "" {
			port = "8080"
		}
		*httpAddr = fmt.Sprintf("0.0.0.0:%s", port)
		pwd, err := os.Getwd()
		if err != nil {
			log.Fatalf("Couldn't get pwd: %v\n", err)
		}
		*basePath = pwd
		*usePlayground = true
		*contentPath = "./content/"
	}

	var fsys fs.FS = embedFS
	if *basePath != "" {
		fsys = os.DirFS(*basePath)
	}
	err := initTemplates(fsys)
	if err != nil {
		log.Fatalf("Failed to parse templates: %v", err)
	}

	ln, err := net.Listen("tcp", *httpAddr)
	if err != nil {
		log.Fatal(err)
	}
	defer ln.Close()

	_, port, err := net.SplitHostPort(ln.Addr().String())
	if err != nil {
		log.Fatal(err)
	}

	origin := &url.URL{Scheme: "http"}
	if *originHost != "" {
		if after, ok := strings.CutPrefix(*originHost, "https://"); ok {
			*originHost = after
			origin.Scheme = "https"
		}
		*originHost = strings.TrimPrefix(*originHost, "http://")
		origin.Host = net.JoinHostPort(*originHost, port)
	} else if ln.Addr().(*net.TCPAddr).IP.IsUnspecified() {
		name, _ := os.Hostname()
		origin.Host = net.JoinHostPort(name, port)
	} else {
		reqHost, reqPort, err := net.SplitHostPort(*httpAddr)
		if err != nil {
			log.Fatal(err)
		}
		if reqPort == "0" {
			origin.Host = net.JoinHostPort(reqHost, port)
		} else {
			origin.Host = *httpAddr
		}
	}

	initPlayground(fsys, origin)
	http.Handle("/static/", http.FileServer(http.FS(fsys)))

	if !ln.Addr().(*net.TCPAddr).IP.IsLoopback() &&
		present.PlayEnabled && !*usePlayground {
		log.Print(localhostWarning)
	}

	log.Printf("Open your web browser and visit %s", origin.String())
	if present.NotesEnabled {
		log.Println("Notes are enabled, press 'N' from the browser to display them.")
	}
	log.Fatal(http.Serve(ln, nil))
}

const localhostWarning = `
WARNING!  WARNING!  WARNING!

The present server appears to be listening on an address that is not localhost
and is configured to run code snippets locally. Anyone with access to this address
and port will have access to this machine as the user running present.

To avoid this message, listen on localhost, run with -play=false, or run with
-play_socket=false.

If you don't understand this message, hit Control-C to terminate this process.

WARNING!  WARNING!  WARNING!
`


================================================
FILE: cmd/present/play.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"fmt"
	"io/fs"
	"net/http"
	"net/url"
	"time"

	"golang.org/x/tools/playground/socket"
	"golang.org/x/tools/present"

	// This will register a handler at /compile that will proxy to the
	// respective endpoints at play.golang.org. This allows the frontend to call
	// these endpoints without needing cross-origin request sharing (CORS).
	// Note that this is imported regardless of whether the endpoints are used or
	// not (in the case of a local socket connection, they are not called).
	_ "golang.org/x/tools/playground"
)

var scripts = []string{"jquery.js", "jquery-ui.js", "playground.js", "play.js"}

// playScript registers an HTTP handler at /play.js that serves all the
// scripts specified by the variable above, and appends a line that
// initializes the playground with the specified transport.
func playScript(fsys fs.FS, transport string) {
	modTime := time.Now()
	var buf bytes.Buffer
	for _, p := range scripts {
		b, err := fs.ReadFile(fsys, "static/"+p)
		if err != nil {
			panic(err)
		}
		buf.Write(b)
	}
	fmt.Fprintf(&buf, "\ninitPlayground(new %v());\n", transport)
	b := buf.Bytes()
	http.HandleFunc("/play.js", func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-type", "application/javascript")
		http.ServeContent(w, r, "", modTime, bytes.NewReader(b))
	})
}

func initPlayground(fsys fs.FS, origin *url.URL) {
	if !present.PlayEnabled {
		return
	}
	if *usePlayground {
		playScript(fsys, "HTTPTransport")
		return
	}

	playScript(fsys, "SocketTransport")
	http.Handle("/socket", socket.NewHandler(origin))
}

func playable(c present.Code) bool {
	play := present.PlayEnabled && c.Play

	// Restrict playable files to only Go source files when using play.golang.org,
	// since there is no method to execute shell scripts there.
	if *usePlayground {
		return play && c.Ext == ".go"
	}
	return play
}


================================================
FILE: cmd/present/static/article.css
================================================
body {
  margin: 0;
  font-family: Helvetica, Arial, sans-serif;
  font-size: 16px;
}
pre,
code {
  font-family: Menlo, monospace;
  font-size: 14px;
}
pre {
  line-height: 18px;
  margin: 0;
  padding: 0;
}
a {
  color: #375eab;
  text-decoration: none;
}
a:hover {
  text-decoration: underline;
}
p,
ul,
ol {
  margin: 20px;
}

h1,
h2,
h3,
h4 {
  margin: 20px 0;
  padding: 0;
  color: #375eab;
  font-weight: bold;
}
h1 {
  font-size: 18px;
  padding: 2px 5px;
}
h2 {
  font-size: 16px;
}
h3 {
  font-size: 16px;
}
h3,
h4 {
  margin: 20px 5px;
}
h4 {
  font-size: 16px;
}

div#heading {
  margin: 0 0 10px 0;
  padding: 21px 0;
  font-size: 20px;
  font-weight: bold;
}

div#heading .author {
  padding-top: 10px;
  font-size: 14px;
  font-weight: normal;
}

div#topbar {
}

body {
  text-align: center;
}
div#page {
  width: 100%;
}
div#page > .container,
div#topbar > .container {
  text-align: left;
  margin-left: auto;
  margin-right: auto;
  padding: 0 20px;
  width: 900px;
}
div#page.wide > .container,
div#topbar.wide > .container {
  width: auto;
}

div#footer {
  text-align: center;
  color: #666;
  font-size: 14px;
  margin: 40px 0;
}

.author p {
  margin: 0;
  padding: 0 20px;
}

div.code,
div.output {
  margin: 0;
}

pre {
  margin: 20px 20px 20px 40px;
  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
}

div.output pre {
  padding: 10px;
}

pre {
  background: white;
}
div.output pre {
  background: black;
}
div.output .stdout pre {
  color: #e6e6e6;
}
div.output .stderr pre {
  color: rgb(244, 74, 63);
}
div.output .system pre {
  color: rgb(255, 209, 77);
}

.buttons {
  margin-left: 20px;
}
div.output .buttons {
  margin-left: 0;
  margin-bottom: 10px;
}

#toc {
  float: right;
  margin: 0px 10px;
  padding: 10px;
  border: 1px solid #e5ecf9;
  background-color: #eee;
  box-shadow: 3px 3px 2px #888888;

  max-width: 33%;

  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
}

#tochead {
  font-weight: bold;
  font-variant: small-caps;
  font-size: 100%;
  text-align: center;
  padding-bottom: 5px;
}

#toc ul,
#toc a {
  list-style-type: none;
  padding-left: 0px;
  color: black;
  margin: 0px;
}

ul.toc-inner a {
  padding-left: 10px !important;
}

@media print {
  .no-print,
  .no-print * {
    display: none !important;
  }
}


================================================
FILE: cmd/present/static/dir.css
================================================
/* copied from $GOROOT/doc/style.css */

body {
  margin: 0;
  font-family: Helvetica, Arial, sans-serif;
  font-size: 16px;
}
pre,
code {
  font-family: Menlo, monospace;
  font-size: 14px;
}
pre {
  line-height: 18px;
}
pre .comment {
  color: #375eab;
}
pre .highlight,
pre .highlight-comment,
pre .selection-highlight,
pre .selection-highlight-comment {
  background: #ffff00;
}
pre .selection,
pre .selection-comment {
  background: #ff9632;
}
pre .ln {
  color: #999;
}
body {
  color: #222;
}
a,
.exampleHeading .text {
  color: #375eab;
  text-decoration: none;
}
a:hover,
.exampleHeading .text:hover {
  text-decoration: underline;
}
p,
pre,
ul,
ol {
  margin: 20px;
}
pre {
  background: #e9e9e9;
  padding: 10px;

  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
}

h1,
h2,
h3,
h4,
.rootHeading {
  margin: 20px 0;
  padding: 0;
  color: #375eab;
  font-weight: bold;
}
h1 {
  font-size: 24px;
}
h2 {
  font-size: 20px;
  background: #e0ebf5;
  padding: 2px 5px;
}
h3 {
  font-size: 20px;
}
h3,
h4 {
  margin: 20px 5px;
}
h4 {
  font-size: 16px;
}

dl {
  margin: 20px;
}
dd {
  margin: 2px 20px;
}
dl,
dd {
  font-size: 14px;
}
div#nav table td {
  vertical-align: top;
}

div#heading {
  float: left;
  margin: 0 0 10px 0;
  padding: 21px 0;
  font-size: 20px;
  font-weight: normal;
}
div#heading a {
  color: #222;
  text-decoration: none;
}

div#topbar {
  background: #e0ebf5;
  height: 64px;
}

body {
  text-align: center;
}
div#page,
div#topbar > .container {
  clear: both;
  text-align: left;
  margin-left: auto;
  margin-right: auto;
  padding: 0 20px;
  width: 900px;
}
div#page.wide,
div#topbar > .wide {
  width: auto;
}
div#plusone {
  float: right;
}

div#footer {
  color: #666;
  font-size: 14px;
  margin: 40px 0;
}

div#menu > a,
div#menu > input {
  padding: 10px;

  text-decoration: none;
  font-size: 16px;

  -webkit-border-radius: 5px;
  -moz-border-radius: 5px;
  border-radius: 5px;
}
div#menu > a,
div#menu > input {
  border: 1px solid #375eab;
}
div#menu > a {
  color: white;
  background: #375eab;
}

div#menu {
  float: right;
  min-width: 590px;
  padding: 10px 0;
  text-align: right;
}
div#menu > a {
  margin-right: 5px;
  margin-bottom: 10px;

  padding: 10px;
}
div#menu > input {
  position: relative;
  top: 1px;
  width: 60px;
  background: white;
  color: #222;
}
div#menu > input.inactive {
  color: #999;
}


================================================
FILE: cmd/present/static/dir.js
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// copied from $GOROOT/doc/godocs.js

function bindEvent(el, e, fn) {
  if (el.addEventListener) {
    el.addEventListener(e, fn, false);
  } else if (el.attachEvent) {
    el.attachEvent('on' + e, fn);
  }
}

function godocs_bindSearchEvents() {
  var search = document.getElementById('search');
  if (!search) {
    // no search box (index disabled)
    return;
  }
  function clearInactive() {
    if (search.className == 'inactive') {
      search.value = '';
      search.className = '';
    }
  }
  function restoreInactive() {
    if (search.value !== '') {
      return;
    }
    if (search.type != 'search') {
      search.value = search.getAttribute('placeholder');
    }
    search.className = 'inactive';
  }
  restoreInactive();
  bindEvent(search, 'focus', clearInactive);
  bindEvent(search, 'blur', restoreInactive);
}

bindEvent(window, 'load', godocs_bindSearchEvents);


================================================
FILE: cmd/present/static/jquery-ui.js
================================================
/*! jQuery UI - v1.10.2 - 2013-03-20
* http://jqueryui.com
* Includes: jquery.ui.core.js, jquery.ui.widget.js, jquery.ui.mouse.js, jquery.ui.resizable.js
* Copyright 2013 jQuery Foundation and other contributors Licensed MIT */

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t;return t=e.ui.ie&&/(static|relative)/.test(this.css("position"))||/absolute/.test(this.css("position"))?this.parents().filter(function(){return/(relative|absolute|fixed)/.test(e.css(this,"position"))&&/(auto|scroll)/.test(e.css(this,"overflow")+e.css(this,"overflow-y")+e.css(this,"overflow-x"))}).eq(0):this.parents().filter(function(){return/(auto|scroll)/.test(e.css(this,"overflow")+e.css(this,"overflow-y")+e.css(this,"overflow-x"))}).eq(0),/fixed/.test(this.css("position"))||!t.length?e(document):t},zIndex:function(i){if(i!==t)return this.css("zIndex",i);if(this.length)for(var s,a,n=e(this[0]);n.length&&n[0]!==document;){if(s=n.css("position"),("absolute"===s||"relative"===s||"fixed"===s)&&(a=parseInt(n.css("zIndex"),10),!isNaN(a)&&0!==a))return a;n=n.parent()}return 0},uniqueId:function(){return this.each(function(){this.id||(this.id="ui-id-"+ ++a)})},removeUniqueId:function(){return 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i===t?o["inner"+s].call(this):this.each(function(){e(this).css(r,a(this,i)+"px")})},e.fn["outer"+s]=function(t,i){return"number"!=typeof t?o["outer"+s].call(this,t):this.each(function(){e(this).css(r,a(this,t,!0,i)+"px")})}}),e.fn.addBack||(e.fn.addBack=function(e){return this.add(null==e?this.prevObject:this.prevObject.filter(e))}),e("<a>").data("a-b","a").removeData("a-b").data("a-b")&&(e.fn.removeData=function(t){return function(i){return arguments.length?t.call(this,e.camelCase(i)):t.call(this)}}(e.fn.removeData)),e.ui.ie=!!/msie [\w.]+/.exec(navigator.userAgent.toLowerCase()),e.support.selectstart="onselectstart"in document.createElement("div"),e.fn.extend({disableSelection:function(){return this.bind((e.support.selectstart?"selectstart":"mousedown")+".ui-disableSelection",function(e){e.preventDefault()})},enableSelection:function(){return this.unbind(".ui-disableSelection")}}),e.extend(e.ui,{plugin:{add:function(t,i,s){var a,n=e.ui[t].prototype;for(a in 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this._setOption("disabled",!1)},disable:function(){return this._setOption("disabled",!0)},_on:function(i,s,n){var a,r=this;"boolean"!=typeof i&&(n=s,s=i,i=!1),n?(s=a=e(s),this.bindings=this.bindings.add(s)):(n=s,s=this.element,a=this.widget()),e.each(n,function(n,o){function h(){return i||r.options.disabled!==!0&&!e(this).hasClass("ui-state-disabled")?("string"==typeof o?r[o]:o).apply(r,arguments):t}"string"!=typeof o&&(h.guid=o.guid=o.guid||h.guid||e.guid++);var l=n.match(/^(\w+)\s*(.*)$/),u=l[1]+r.eventNamespace,c=l[2];c?a.delegate(c,u,h):s.bind(u,h)})},_off:function(e,t){t=(t||"").split(" ").join(this.eventNamespace+" ")+this.eventNamespace,e.unbind(t).undelegate(t)},_delay:function(e,t){function i(){return("string"==typeof e?s[e]:e).apply(s,arguments)}var s=this;return setTimeout(i,t||0)},_hoverable:function(t){this.hoverable=this.hoverable.add(t),this._on(t,{mouseenter:function(t){e(t.currentTarget).addClass("ui-state-hover")},mouseleave:function(t){e(t.currentTarget).removeClass("ui-state-hover")}})},_focusable:function(t){this.focusable=this.focusable.add(t),this._on(t,{focusin:function(t){e(t.currentTarget).addClass("ui-state-focus")},focusout:function(t){e(t.currentTarget).removeClass("ui-state-focus")}})},_trigger:function(t,i,s){var n,a,r=this.options[t];if(s=s||{},i=e.Event(i),i.type=(t===this.widgetEventPrefix?t:this.widgetEventPrefix+t).toLowerCase(),i.target=this.element[0],a=i.originalEvent)for(n in a)n in i||(i[n]=a[n]);return this.element.trigger(i,s),!(e.isFunction(r)&&r.apply(this.element[0],[i].concat(s))===!1||i.isDefaultPrevented())}},e.each({show:"fadeIn",hide:"fadeOut"},function(t,i){e.Widget.prototype["_"+t]=function(s,n,a){"string"==typeof n&&(n={effect:n});var r,o=n?n===!0||"number"==typeof 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t._mouseDown(e)}).bind("click."+this.widgetName,function(i){return!0===e.data(i.target,t.widgetName+".preventClickEvent")?(e.removeData(i.target,t.widgetName+".preventClickEvent"),i.stopImmediatePropagation(),!1):undefined}),this.started=!1},_mouseDestroy:function(){this.element.unbind("."+this.widgetName),this._mouseMoveDelegate&&e(document).unbind("mousemove."+this.widgetName,this._mouseMoveDelegate).unbind("mouseup."+this.widgetName,this._mouseUpDelegate)},_mouseDown:function(i){if(!t){this._mouseStarted&&this._mouseUp(i),this._mouseDownEvent=i;var s=this,n=1===i.which,a="string"==typeof this.options.cancel&&i.target.nodeName?e(i.target).closest(this.options.cancel).length:!1;return n&&!a&&this._mouseCapture(i)?(this.mouseDelayMet=!this.options.delay,this.mouseDelayMet||(this._mouseDelayTimer=setTimeout(function(){s.mouseDelayMet=!0},this.options.delay)),this._mouseDistanceMet(i)&&this._mouseDelayMet(i)&&(this._mouseStarted=this._mouseStart(i)!==!1,!this._mouseStarted)?(i.preventDefault(),!0):(!0===e.data(i.target,this.widgetName+".preventClickEvent")&&e.removeData(i.target,this.widgetName+".preventClickEvent"),this._mouseMoveDelegate=function(e){return s._mouseMove(e)},this._mouseUpDelegate=function(e){return s._mouseUp(e)},e(document).bind("mousemove."+this.widgetName,this._mouseMoveDelegate).bind("mouseup."+this.widgetName,this._mouseUpDelegate),i.preventDefault(),t=!0,!0)):!0}},_mouseMove:function(t){return e.ui.ie&&(!document.documentMode||9>document.documentMode)&&!t.button?this._mouseUp(t):this._mouseStarted?(this._mouseDrag(t),t.preventDefault()):(this._mouseDistanceMet(t)&&this._mouseDelayMet(t)&&(this._mouseStarted=this._mouseStart(this._mouseDownEvent,t)!==!1,this._mouseStarted?this._mouseDrag(t):this._mouseUp(t)),!this._mouseStarted)},_mouseUp:function(t){return e(document).unbind("mousemove."+this.widgetName,this._mouseMoveDelegate).unbind("mouseup."+this.widgetName,this._mouseUpDelegate),this._mouseStarted&&(this._mouseStarted=!1,t.target===this._mouseDownEvent.target&&e.data(t.target,this.widgetName+".preventClickEvent",!0),this._mouseStop(t)),!1},_mouseDistanceMet:function(e){return Math.max(Math.abs(this._mouseDownEvent.pageX-e.pageX),Math.abs(this._mouseDownEvent.pageY-e.pageY))>=this.options.distance},_mouseDelayMet:function(){return this.mouseDelayMet},_mouseStart:function(){},_mouseDrag:function(){},_mouseStop:function(){},_mouseCapture:function(){return!0}})})(jQuery);(function(e){function t(e){return parseInt(e,10)||0}function i(e){return!isNaN(parseInt(e,10))}e.widget("ui.resizable",e.ui.mouse,{version:"1.10.2",widgetEventPrefix:"resize",options:{alsoResize:!1,animate:!1,animateDuration:"slow",animateEasing:"swing",aspectRatio:!1,autoHide:!1,containment:!1,ghost:!1,grid:!1,handles:"e,s,se",helper:!1,maxHeight:null,maxWidth:null,minHeight:10,minWidth:10,zIndex:90,resize:null,start:null,stop:null},_create:function(){var t,i,s,n,a,o=this,r=this.options;if(this.element.addClass("ui-resizable"),e.extend(this,{_aspectRatio:!!r.aspectRatio,aspectRatio:r.aspectRatio,originalElement:this.element,_proportionallyResizeElements:[],_helper:r.helper||r.ghost||r.animate?r.helper||"ui-resizable-helper":null}),this.element[0].nodeName.match(/canvas|textarea|input|select|button|img/i)&&(this.element.wrap(e("<div class='ui-wrapper' style='overflow: hidden;'></div>").css({position:this.element.css("position"),width:this.element.outerWidth(),height:this.element.outerHeight(),top:this.element.css("top"),left:this.element.css("left")})),this.element=this.element.parent().data("ui-resizable",this.element.data("ui-resizable")),this.elementIsWrapper=!0,this.element.css({marginLeft:this.originalElement.css("marginLeft"),marginTop:this.originalElement.css("marginTop"),marginRight:this.originalElement.css("marginRight"),marginBottom:this.originalElement.css("marginBottom")}),this.originalElement.css({marginLeft:0,marginTop:0,marginRight:0,marginBottom:0}),this.originalResizeStyle=this.originalElement.css("resize"),this.originalElement.css("resize","none"),this._proportionallyResizeElements.push(this.originalElement.css({position:"static",zoom:1,display:"block"})),this.originalElement.css({margin:this.originalElement.css("margin")}),this._proportionallyResize()),this.handles=r.handles||(e(".ui-resizable-handle",this.element).length?{n:".ui-resizable-n",e:".ui-resizable-e",s:".ui-resizable-s",w:".ui-resizable-w",se:".ui-resizable-se",sw:".ui-resizable-sw",ne:".ui-resizable-ne",nw:".ui-resizable-nw"}:"e,s,se"),this.handles.constructor===String)for("all"===this.handles&&(this.handles="n,e,s,w,se,sw,ne,nw"),t=this.handles.split(","),this.handles={},i=0;t.length>i;i++)s=e.trim(t[i]),a="ui-resizable-"+s,n=e("<div class='ui-resizable-handle "+a+"'></div>"),n.css({zIndex:r.zIndex}),"se"===s&&n.addClass("ui-icon ui-icon-gripsmall-diagonal-se"),this.handles[s]=".ui-resizable-"+s,this.element.append(n);this._renderAxis=function(t){var i,s,n,a;t=t||this.element;for(i in this.handles)this.handles[i].constructor===String&&(this.handles[i]=e(this.handles[i],this.element).show()),this.elementIsWrapper&&this.originalElement[0].nodeName.match(/textarea|input|select|button/i)&&(s=e(this.handles[i],this.element),a=/sw|ne|nw|se|n|s/.test(i)?s.outerHeight():s.outerWidth(),n=["padding",/ne|nw|n/.test(i)?"Top":/se|sw|s/.test(i)?"Bottom":/^e$/.test(i)?"Right":"Left"].join(""),t.css(n,a),this._proportionallyResize()),e(this.handles[i]).length},this._renderAxis(this.element),this._handles=e(".ui-resizable-handle",this.element).disableSelection(),this._handles.mouseover(function(){o.resizing||(this.className&&(n=this.className.match(/ui-resizable-(se|sw|ne|nw|n|e|s|w)/i)),o.axis=n&&n[1]?n[1]:"se")}),r.autoHide&&(this._handles.hide(),e(this.element).addClass("ui-resizable-autohide").mouseenter(function(){r.disabled||(e(this).removeClass("ui-resizable-autohide"),o._handles.show())}).mouseleave(function(){r.disabled||o.resizing||(e(this).addClass("ui-resizable-autohide"),o._handles.hide())})),this._mouseInit()},_destroy:function(){this._mouseDestroy();var t,i=function(t){e(t).removeClass("ui-resizable ui-resizable-disabled ui-resizable-resizing").removeData("resizable").removeData("ui-resizable").unbind(".resizable").find(".ui-resizable-handle").remove()};return this.elementIsWrapper&&(i(this.element),t=this.element,this.originalElement.css({position:t.css("position"),width:t.outerWidth(),height:t.outerHeight(),top:t.css("top"),left:t.css("left")}).insertAfter(t),t.remove()),this.originalElement.css("resize",this.originalResizeStyle),i(this.originalElement),this},_mouseCapture:function(t){var i,s,n=!1;for(i in this.handles)s=e(this.handles[i])[0],(s===t.target||e.contains(s,t.target))&&(n=!0);return!this.options.disabled&&n},_mouseStart:function(i){var s,n,a,o=this.options,r=this.element.position(),h=this.element;return this.resizing=!0,/absolute/.test(h.css("position"))?h.css({position:"absolute",top:h.css("top"),left:h.css("left")}):h.is(".ui-draggable")&&h.css({position:"absolute",top:r.top,left:r.left}),this._renderProxy(),s=t(this.helper.css("left")),n=t(this.helper.css("top")),o.containment&&(s+=e(o.containment).scrollLeft()||0,n+=e(o.containment).scrollTop()||0),this.offset=this.helper.offset(),this.position={left:s,top:n},this.size=this._helper?{width:h.outerWidth(),height:h.outerHeight()}:{width:h.width(),height:h.height()},this.originalSize=this._helper?{width:h.outerWidth(),height:h.outerHeight()}:{width:h.width(),height:h.height()},this.originalPosition={left:s,top:n},this.sizeDiff={width:h.outerWidth()-h.width(),height:h.outerHeight()-h.height()},this.originalMousePosition={left:i.pageX,top:i.pageY},this.aspectRatio="number"==typeof o.aspectRatio?o.aspectRatio:this.originalSize.width/this.originalSize.height||1,a=e(".ui-resizable-"+this.axis).css("cursor"),e("body").css("cursor","auto"===a?this.axis+"-resize":a),h.addClass("ui-resizable-resizing"),this._propagate("start",i),!0},_mouseDrag:function(t){var i,s=this.helper,n={},a=this.originalMousePosition,o=this.axis,r=this.position.top,h=this.position.left,l=this.size.width,u=this.size.height,c=t.pageX-a.left||0,d=t.pageY-a.top||0,p=this._change[o];return p?(i=p.apply(this,[t,c,d]),this._updateVirtualBoundaries(t.shiftKey),(this._aspectRatio||t.shiftKey)&&(i=this._updateRatio(i,t)),i=this._respectSize(i,t),this._updateCache(i),this._propagate("resize",t),this.position.top!==r&&(n.top=this.position.top+"px"),this.position.left!==h&&(n.left=this.position.left+"px"),this.size.width!==l&&(n.width=this.size.width+"px"),this.size.height!==u&&(n.height=this.size.height+"px"),s.css(n),!this._helper&&this._proportionallyResizeElements.length&&this._proportionallyResize(),e.isEmptyObject(n)||this._trigger("resize",t,this.ui()),!1):!1},_mouseStop:function(t){this.resizing=!1;var i,s,n,a,o,r,h,l=this.options,u=this;return this._helper&&(i=this._proportionallyResizeElements,s=i.length&&/textarea/i.test(i[0].nodeName),n=s&&e.ui.hasScroll(i[0],"left")?0:u.sizeDiff.height,a=s?0:u.sizeDiff.width,o={width:u.helper.width()-a,height:u.helper.height()-n},r=parseInt(u.element.css("left"),10)+(u.position.left-u.originalPosition.left)||null,h=parseInt(u.element.css("top"),10)+(u.position.top-u.originalPosition.top)||null,l.animate||this.element.css(e.extend(o,{top:h,left:r})),u.helper.height(u.size.height),u.helper.width(u.size.width),this._helper&&!l.animate&&this._proportionallyResize()),e("body").css("cursor","auto"),this.element.removeClass("ui-resizable-resizing"),this._propagate("stop",t),this._helper&&this.helper.remove(),!1},_updateVirtualBoundaries:function(e){var t,s,n,a,o,r=this.options;o={minWidth:i(r.minWidth)?r.minWidth:0,maxWidth:i(r.maxWidth)?r.maxWidth:1/0,minHeight:i(r.minHeight)?r.minHeight:0,maxHeight:i(r.maxHeight)?r.maxHeight:1/0},(this._aspectRatio||e)&&(t=o.minHeight*this.aspectRatio,n=o.minWidth/this.aspectRatio,s=o.maxHeight*this.aspectRatio,a=o.maxWidth/this.aspectRatio,t>o.minWidth&&(o.minWidth=t),n>o.minHeight&&(o.minHeight=n),o.maxWidth>s&&(o.maxWidth=s),o.maxHeight>a&&(o.maxHeight=a)),this._vBoundaries=o},_updateCache:function(e){this.offset=this.helper.offset(),i(e.left)&&(this.position.left=e.left),i(e.top)&&(this.position.top=e.top),i(e.height)&&(this.size.height=e.height),i(e.width)&&(this.size.width=e.width)},_updateRatio:function(e){var t=this.position,s=this.size,n=this.axis;return i(e.height)?e.width=e.height*this.aspectRatio:i(e.width)&&(e.height=e.width/this.aspectRatio),"sw"===n&&(e.left=t.left+(s.width-e.width),e.top=null),"nw"===n&&(e.top=t.top+(s.height-e.height),e.left=t.left+(s.width-e.width)),e},_respectSize:function(e){var t=this._vBoundaries,s=this.axis,n=i(e.width)&&t.maxWidth&&t.maxWidth<e.width,a=i(e.height)&&t.maxHeight&&t.maxHeight<e.height,o=i(e.width)&&t.minWidth&&t.minWidth>e.width,r=i(e.height)&&t.minHeight&&t.minHeight>e.height,h=this.originalPosition.left+this.originalSize.width,l=this.position.top+this.size.height,u=/sw|nw|w/.test(s),c=/nw|ne|n/.test(s);return o&&(e.width=t.minWidth),r&&(e.height=t.minHeight),n&&(e.width=t.maxWidth),a&&(e.height=t.maxHeight),o&&u&&(e.left=h-t.minWidth),n&&u&&(e.left=h-t.maxWidth),r&&c&&(e.top=l-t.minHeight),a&&c&&(e.top=l-t.maxHeight),e.width||e.height||e.left||!e.top?e.width||e.height||e.top||!e.left||(e.left=null):e.top=null,e},_proportionallyResize:function(){if(this._proportionallyResizeElements.length){var e,t,i,s,n,a=this.helper||this.element;for(e=0;this._proportionallyResizeElements.length>e;e++){if(n=this._proportionallyResizeElements[e],!this.borderDif)for(this.borderDif=[],i=[n.css("borderTopWidth"),n.css("borderRightWidth"),n.css("borderBottomWidth"),n.css("borderLeftWidth")],s=[n.css("paddingTop"),n.css("paddingRight"),n.css("paddingBottom"),n.css("paddingLeft")],t=0;i.length>t;t++)this.borderDif[t]=(parseInt(i[t],10)||0)+(parseInt(s[t],10)||0);n.css({height:a.height()-this.borderDif[0]-this.borderDif[2]||0,width:a.width()-this.borderDif[1]-this.borderDif[3]||0})}}},_renderProxy:function(){var t=this.element,i=this.options;this.elementOffset=t.offset(),this._helper?(this.helper=this.helper||e("<div style='overflow:hidden;'></div>"),this.helper.addClass(this._helper).css({width:this.element.outerWidth()-1,height:this.element.outerHeight()-1,position:"absolute",left:this.elementOffset.left+"px",top:this.elementOffset.top+"px",zIndex:++i.zIndex}),this.helper.appendTo("body").disableSelection()):this.helper=this.element},_change:{e:function(e,t){return{width:this.originalSize.width+t}},w:function(e,t){var i=this.originalSize,s=this.originalPosition;return{left:s.left+t,width:i.width-t}},n:function(e,t,i){var s=this.originalSize,n=this.originalPosition;return{top:n.top+i,height:s.height-i}},s:function(e,t,i){return{height:this.originalSize.height+i}},se:function(t,i,s){return e.extend(this._change.s.apply(this,arguments),this._change.e.apply(this,[t,i,s]))},sw:function(t,i,s){return e.extend(this._change.s.apply(this,arguments),this._change.w.apply(this,[t,i,s]))},ne:function(t,i,s){return e.extend(this._change.n.apply(this,arguments),this._change.e.apply(this,[t,i,s]))},nw:function(t,i,s){return e.extend(this._change.n.apply(this,arguments),this._change.w.apply(this,[t,i,s]))}},_propagate:function(t,i){e.ui.plugin.call(this,t,[i,this.ui()]),"resize"!==t&&this._trigger(t,i,this.ui())},plugins:{},ui:function(){return{originalElement:this.originalElement,element:this.element,helper:this.helper,position:this.position,size:this.size,originalSize:this.originalSize,originalPosition:this.originalPosition}}}),e.ui.plugin.add("resizable","animate",{stop:function(t){var i=e(this).data("ui-resizable"),s=i.options,n=i._proportionallyResizeElements,a=n.length&&/textarea/i.test(n[0].nodeName),o=a&&e.ui.hasScroll(n[0],"left")?0:i.sizeDiff.height,r=a?0:i.sizeDiff.width,h={width:i.size.width-r,height:i.size.height-o},l=parseInt(i.element.css("left"),10)+(i.position.left-i.originalPosition.left)||null,u=parseInt(i.element.css("top"),10)+(i.position.top-i.originalPosition.top)||null;i.element.animate(e.extend(h,u&&l?{top:u,left:l}:{}),{duration:s.animateDuration,easing:s.animateEasing,step:function(){var s={width:parseInt(i.element.css("width"),10),height:parseInt(i.element.css("height"),10),top:parseInt(i.element.css("top"),10),left:parseInt(i.element.css("left"),10)};n&&n.length&&e(n[0]).css({width:s.width,height:s.height}),i._updateCache(s),i._propagate("resize",t)}})}}),e.ui.plugin.add("resizable","containment",{start:function(){var i,s,n,a,o,r,h,l=e(this).data("ui-resizable"),u=l.options,c=l.element,d=u.containment,p=d instanceof 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c=="object"?c[p.expando]?c:new p.Event(s,c):new p.Event(s),c.type=s,c.isTrigger=!0,c.exclusive=i,c.namespace=t.join("."),c.namespace_re=c.namespace?new RegExp("(^|\\.)"+t.join("\\.(?:.*\\.|)")+"(\\.|$)"):null,m=s.indexOf(":")<0?"on"+s:"";if(!f){h=p.cache;for(j in h)h[j].events&&h[j].events[s]&&p.event.trigger(c,d,h[j].handle.elem,!0);return}c.result=b,c.target||(c.target=f),d=d!=null?p.makeArray(d):[],d.unshift(c),n=p.event.special[s]||{};if(n.trigger&&n.trigger.apply(f,d)===!1)return;q=[[f,n.bindType||s]];if(!g&&!n.noBubble&&!p.isWindow(f)){r=n.delegateType||s,k=$.test(r+s)?f:f.parentNode;for(l=f;k;k=k.parentNode)q.push([k,r]),l=k;l===(f.ownerDocument||e)&&q.push([l.defaultView||l.parentWindow||a,r])}for(j=0;j<q.length&&!c.isPropagationStopped();j++)k=q[j][0],c.type=q[j][1],o=(p._data(k,"events")||{})[c.type]&&p._data(k,"handle"),o&&o.apply(k,d),o=m&&k[m],o&&p.acceptData(k)&&o.apply&&o.apply(k,d)===!1&&c.preventDefault();return 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================================================
FILE: cmd/present/static/notes.css
================================================
p {
  margin: 10px;
}

#presenter-slides {
  display: block;
  margin-top: -10px;
  margin-left: -17px;
  position: fixed;
  border: 0;
  width: 146%;
  height: 750px;

  transform: scale(0.7, 0.7);
  transform-origin: top left;
  -moz-transform: scale(0.7);
  -moz-transform-origin: top left;
  -o-transform: scale(0.7);
  -o-transform-origin: top left;
  -webkit-transform: scale(0.7);
  -webkit-transform-origin: top left;
}

#presenter-notes {
  margin-top: -180px;
  font-family: 'Open Sans', Arial, sans-serif;
  height: 30%;
  width: 100%;
  overflow: scroll;
  position: fixed;
  top: 706px;
}


================================================
FILE: cmd/present/static/notes.js
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Store child window object which will display slides with notes
var notesWindow = null;

var isParentWindow = window.parent == window;

// When parent window closes, clear storage and close child window
if (isParentWindow) {
  window.onbeforeunload = function() {
    localStorage.clear();
    if (notesWindow) notesWindow.close();
  };
}

function toggleNotesWindow() {
  if (!isParentWindow) return;
  if (notesWindow) {
    notesWindow.close();
    notesWindow = null;
    return;
  }

  initNotes();
}

// Create a unique key for the local storage so we don't mix the
// destSlide of different presentations. For golang.org/issue/24688.
function destSlideKey() {
  var key = '';
  if (notesWindow) {
    var slides = notesWindow.document.getElementById('presenter-slides');
    key = slides.src.split('#')[0];
  } else {
    key = window.location.href.split('#')[0];
  }
  return 'destSlide:' + key;
}

function initNotes() {
  notesWindow = window.open('', '', 'width=1000,height=700');
  var w = notesWindow;
  var slidesUrl = window.location.href;

  // Hack to apply css. Requires existing html on notesWindow.
  w.document.write("<div style='display:none;'></div>");

  w.document.title = window.document.title;

  var slides = w.document.createElement('iframe');
  slides.id = 'presenter-slides';
  slides.src = slidesUrl;
  w.document.body.appendChild(slides);

  var curSlide = parseInt(localStorage.getItem(destSlideKey()), 10);
  var formattedNotes = '';
  var section = sections[curSlide - 1];
  // curSlide is 0 when initialized from the first page of slides.
  // Check if section is valid before retrieving Notes.
  if (section) {
    formattedNotes = formatNotes(section.Notes);
  } else if (curSlide == 0) {
    formattedNotes = formatNotes(titleNotes);
  }

  // setTimeout needed for Firefox
  setTimeout(function() {
    slides.focus();
  }, 100);

  var notes = w.document.createElement('div');
  notes.id = 'presenter-notes';
  notes.innerHTML = formattedNotes;
  w.document.body.appendChild(notes);

  w.document.close();

  function addPresenterNotesStyle() {
    var el = w.document.createElement('link');
    el.rel = 'stylesheet';
    el.type = 'text/css';
    el.href = PERMANENT_URL_PREFIX + 'notes.css';
    w.document.body.appendChild(el);
    w.document.querySelector('head').appendChild(el);
  }

  addPresenterNotesStyle();

  // Add listener on notesWindow to update notes when triggered from
  // parent window
  w.addEventListener('storage', updateNotes, false);
}

function formatNotes(notes) {
  var formattedNotes = '';
  if (notes) {
    for (var i = 0; i < notes.length; i++) {
      formattedNotes = formattedNotes + '<p>' + notes[i] + '</p>';
    }
  }
  return formattedNotes;
}

function updateNotes() {
  // When triggered from parent window, notesWindow is null
  // The storage event listener on notesWindow will update notes
  if (!notesWindow) return;
  var destSlide = parseInt(localStorage.getItem(destSlideKey()), 10);
  var section = sections[destSlide - 1];
  var el = notesWindow.document.getElementById('presenter-notes');

  if (!el) return;

  if (section && section.Notes) {
    el.innerHTML = formatNotes(section.Notes);
  } else if (destSlide == 0) {
    el.innerHTML = formatNotes(titleNotes);
  } else {
    el.innerHTML = '';
  }
}

/* Playground syncing */

// When presenter notes are enabled, playground click handlers are
// stored here to sync click events on the correct playground
var playgroundHandlers = { onRun: [], onKill: [], onClose: [] };

function updatePlay(e) {
  var i = localStorage.getItem('play-index');

  switch (e.key) {
    case 'play-index':
      return;
    case 'play-action':
      // Sync 'run', 'kill', 'close' actions
      var action = localStorage.getItem('play-action');
      playgroundHandlers[action][i](e);
      return;
    case 'play-code':
      // Sync code editing
      var play = document.querySelectorAll('div.playground')[i];
      play.innerHTML = localStorage.getItem('play-code');
      return;
    case 'output-style':
      // Sync resizing of playground output
      var out = document.querySelectorAll('.output')[i];
      out.style = localStorage.getItem('output-style');
      return;
  }
}

// Reset 'run', 'kill', 'close' storage items when synced
// so that successive actions can be synced correctly
function updatePlayStorage(action, index, e) {
  localStorage.setItem('play-index', index);

  if (localStorage.getItem('play-action') === action) {
    // We're the receiving window, and the message has been received
    localStorage.removeItem('play-action');
  } else {
    // We're the triggering window, send the message
    localStorage.setItem('play-action', action);
  }

  if (action === 'onRun') {
    if (localStorage.getItem('play-shiftKey') === 'true') {
      localStorage.removeItem('play-shiftKey');
    } else if (e.shiftKey) {
      localStorage.setItem('play-shiftKey', e.shiftKey);
    }
  }
}


================================================
FILE: cmd/present/static/play.js
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

function initPlayground(transport) {
  'use strict';

  function text(node) {
    var s = '';
    for (var i = 0; i < node.childNodes.length; i++) {
      var n = node.childNodes[i];
      if (n.nodeType === 1) {
        if (n.tagName === 'BUTTON') continue;
        if (n.tagName === 'SPAN' && n.className === 'number') continue;
        if (n.tagName === 'DIV' || n.tagName === 'BR' || n.tagName === 'PRE') {
          s += '\n';
        }
        s += text(n);
        continue;
      }
      if (n.nodeType === 3) {
        s += n.nodeValue;
      }
    }
    return s.replace('\xA0', ' '); // replace non-breaking spaces
  }

  // When presenter notes are enabled, the index passed
  // here will identify the playground to be synced
  function init(code, index) {
    var output = document.createElement('div');
    var outpre = document.createElement('pre');
    var running;

    if ($ && $(output).resizable) {
      $(output).resizable({
        handles: 'n,w,nw',
        minHeight: 27,
        minWidth: 135,
        maxHeight: 608,
        maxWidth: 990,
      });
    }

    function onKill() {
      if (running) running.Kill();
      if (window.notesEnabled) updatePlayStorage('onKill', index);
    }

    function onRun(e) {
      var sk = e.shiftKey || localStorage.getItem('play-shiftKey') === 'true';
      if (running) running.Kill();
      output.style.display = 'block';
      outpre.textContent = '';
      run1.style.display = 'none';
      var options = { Race: sk };
      running = transport.Run(text(code), PlaygroundOutput(outpre), options);
      if (window.notesEnabled) updatePlayStorage('onRun', index, e);
    }

    function onClose() {
      if (running) running.Kill();
      output.style.display = 'none';
      run1.style.display = 'inline-block';
      if (window.notesEnabled) updatePlayStorage('onClose', index);
    }

    if (window.notesEnabled) {
      playgroundHandlers.onRun.push(onRun);
      playgroundHandlers.onClose.push(onClose);
      playgroundHandlers.onKill.push(onKill);
    }

    var run1 = document.createElement('button');
    run1.textContent = 'Run';
    run1.className = 'run';
    run1.addEventListener('click', onRun, false);
    var run2 = document.createElement('button');
    run2.className = 'run';
    run2.textContent = 'Run';
    run2.addEventListener('click', onRun, false);
    var kill = document.createElement('button');
    kill.className = 'kill';
    kill.textContent = 'Kill';
    kill.addEventListener('click', onKill, false);
    var close = document.createElement('button');
    close.className = 'close';
    close.textContent = 'Close';
    close.addEventListener('click', onClose, false);

    var button = document.createElement('div');
    button.classList.add('buttons');
    button.appendChild(run1);
    // Hack to simulate insertAfter
    code.parentNode.insertBefore(button, code.nextSibling);

    var buttons = document.createElement('div');
    buttons.classList.add('buttons');
    buttons.appendChild(run2);
    buttons.appendChild(kill);
    buttons.appendChild(close);

    output.classList.add('output');
    output.appendChild(buttons);
    output.appendChild(outpre);
    output.style.display = 'none';
    code.parentNode.insertBefore(output, button.nextSibling);
  }

  var play = document.querySelectorAll('div.playground');
  for (var i = 0; i < play.length; i++) {
    init(play[i], i);
  }
}


================================================
FILE: cmd/present/static/playground.js
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
In the absence of any formal way to specify interfaces in JavaScript,
here's a skeleton implementation of a playground transport.

        function Transport() {
                // Set up any transport state (eg, make a websocket connection).
                return {
                        Run: function(body, output, options) {
                                // Compile and run the program 'body' with 'options'.
				// Call the 'output' callback to display program output.
                                return {
                                        Kill: function() {
                                                // Kill the running program.
                                        }
                                };
                        }
                };
        }

	// The output callback is called multiple times, and each time it is
	// passed an object of this form.
        var write = {
                Kind: 'string', // 'start', 'stdout', 'stderr', 'end'
                Body: 'string'  // content of write or end status message
        }

	// The first call must be of Kind 'start' with no body.
	// Subsequent calls may be of Kind 'stdout' or 'stderr'
	// and must have a non-null Body string.
	// The final call should be of Kind 'end' with an optional
	// Body string, signifying a failure ("killed", for example).

	// The output callback must be of this form.
	// See PlaygroundOutput (below) for an implementation.
        function outputCallback(write) {
        }
*/

// HTTPTransport is the default transport.
// enableVet enables running vet if a program was compiled and ran successfully.
// If vet returned any errors, display them before the output of a program.
function HTTPTransport(enableVet) {
  'use strict';

  function playback(output, data) {
    // Backwards compatibility: default values do not affect the output.
    var events = data.Events || [];
    var errors = data.Errors || '';
    var status = data.Status || 0;
    var isTest = data.IsTest || false;
    var testsFailed = data.TestsFailed || 0;

    var timeout;
    output({ Kind: 'start' });
    function next() {
      if (!events || events.length === 0) {
        if (isTest) {
          if (testsFailed > 0) {
            output({
              Kind: 'system',
              Body:
                '\n' +
                testsFailed +
                ' test' +
                (testsFailed > 1 ? 's' : '') +
                ' failed.',
            });
          } else {
            output({ Kind: 'system', Body: '\nAll tests passed.' });
          }
        } else {
          if (status > 0) {
            output({ Kind: 'end', Body: 'status ' + status + '.' });
          } else {
            if (errors !== '') {
              // errors are displayed only in the case of timeout.
              output({ Kind: 'end', Body: errors + '.' });
            } else {
              output({ Kind: 'end' });
            }
          }
        }
        return;
      }
      var e = events.shift();
      if (e.Delay === 0) {
        output({ Kind: e.Kind, Body: e.Message });
        next();
        return;
      }
      timeout = setTimeout(function() {
        output({ Kind: e.Kind, Body: e.Message });
        next();
      }, e.Delay / 1000000);
    }
    next();
    return {
      Stop: function() {
        clearTimeout(timeout);
      },
    };
  }

  function error(output, msg) {
    output({ Kind: 'start' });
    output({ Kind: 'stderr', Body: msg });
    output({ Kind: 'end' });
  }

  function buildFailed(output, msg) {
    output({ Kind: 'start' });
    output({ Kind: 'stderr', Body: msg });
    output({ Kind: 'system', Body: '\nGo build failed.' });
  }

  var seq = 0;
  return {
    Run: function(body, output, options) {
      seq++;
      var cur = seq;
      var playing;
      $.ajax('/compile', {
        type: 'POST',
        data: { version: 2, body: body, withVet: enableVet },
        dataType: 'json',
        success: function(data) {
          if (seq != cur) return;
          if (!data) return;
          if (playing != null) playing.Stop();
          if (data.Errors) {
            if (data.Errors === 'process took too long') {
              // Playback the output that was captured before the timeout.
              playing = playback(output, data);
            } else {
              buildFailed(output, data.Errors);
            }
            return;
          }
          if (!data.Events) {
            data.Events = [];
          }
          if (data.VetErrors) {
            // Inject errors from the vet as the first events in the output.
            data.Events.unshift({
              Message: 'Go vet exited.\n\n',
              Kind: 'system',
              Delay: 0,
            });
            data.Events.unshift({
              Message: data.VetErrors,
              Kind: 'stderr',
              Delay: 0,
            });
          }

          if (!enableVet || data.VetOK || data.VetErrors) {
            playing = playback(output, data);
            return;
          }

          // In case the server support doesn't support
          // compile+vet in same request signaled by the
          // 'withVet' parameter above, also try the old way.
          // TODO: remove this when it falls out of use.
          // It is 2019-05-13 now.
          $.ajax('/vet', {
            data: { body: body },
            type: 'POST',
            dataType: 'json',
            success: function(dataVet) {
              if (dataVet.Errors) {
                // inject errors from the vet as the first events in the output
                data.Events.unshift({
                  Message: 'Go vet exited.\n\n',
                  Kind: 'system',
                  Delay: 0,
                });
                data.Events.unshift({
                  Message: dataVet.Errors,
                  Kind: 'stderr',
                  Delay: 0,
                });
              }
              playing = playback(output, data);
            },
            error: function() {
              playing = playback(output, data);
            },
          });
        },
        error: function() {
          error(output, 'Error communicating with remote server.');
        },
      });
      return {
        Kill: function() {
          if (playing != null) playing.Stop();
          output({ Kind: 'end', Body: 'killed' });
        },
      };
    },
  };
}

function SocketTransport() {
  'use strict';

  var id = 0;
  var outputs = {};
  var started = {};
  var websocket;
  if (window.location.protocol == 'http:') {
    websocket = new WebSocket('ws://' + window.location.host + '/socket');
  } else if (window.location.protocol == 'https:') {
    websocket = new WebSocket('wss://' + window.location.host + '/socket');
  }

  websocket.onclose = function() {
    console.log('websocket connection closed');
  };

  websocket.onmessage = function(e) {
    var m = JSON.parse(e.data);
    var output = outputs[m.Id];
    if (output === null) return;
    if (!started[m.Id]) {
      output({ Kind: 'start' });
      started[m.Id] = true;
    }
    output({ Kind: m.Kind, Body: m.Body });
  };

  function send(m) {
    websocket.send(JSON.stringify(m));
  }

  return {
    Run: function(body, output, options) {
      var thisID = id + '';
      id++;
      outputs[thisID] = output;
      send({ Id: thisID, Kind: 'run', Body: body, Options: options });
      return {
        Kill: function() {
          send({ Id: thisID, Kind: 'kill' });
        },
      };
    },
  };
}

function PlaygroundOutput(el) {
  'use strict';

  return function(write) {
    if (write.Kind == 'start') {
      el.innerHTML = '';
      return;
    }

    var cl = 'system';
    if (write.Kind == 'stdout' || write.Kind == 'stderr') cl = write.Kind;

    var m = write.Body;
    if (write.Kind == 'end') {
      m = '\nProgram exited' + (m ? ': ' + m : '.');
    }

    if (m.indexOf('IMAGE:') === 0) {
      // TODO(adg): buffer all writes before creating image
      var url = 'data:image/png;base64,' + m.substr(6);
      var img = document.createElement('img');
      img.src = url;
      el.appendChild(img);
      return;
    }

    // ^L clears the screen.
    var s = m.split('\x0c');
    if (s.length > 1) {
      el.innerHTML = '';
      m = s.pop();
    }

    m = m.replace(/&/g, '&amp;');
    m = m.replace(/</g, '&lt;');
    m = m.replace(/>/g, '&gt;');

    var needScroll = el.scrollTop + el.offsetHeight == el.scrollHeight;

    var span = document.createElement('span');
    span.className = cl;
    span.innerHTML = m;
    el.appendChild(span);

    if (needScroll) el.scrollTop = el.scrollHeight - el.offsetHeight;
  };
}

(function() {
  function lineHighlight(error) {
    var regex = /prog.go:([0-9]+)/g;
    var r = regex.exec(error);
    while (r) {
      $('.lines div')
        .eq(r[1] - 1)
        .addClass('lineerror');
      r = regex.exec(error);
    }
  }
  function highlightOutput(wrappedOutput) {
    return function(write) {
      if (write.Body) lineHighlight(write.Body);
      wrappedOutput(write);
    };
  }
  function lineClear() {
    $('.lineerror').removeClass('lineerror');
  }

  // opts is an object with these keys
  //  codeEl - code editor element
  //  outputEl - program output element
  //  runEl - run button element
  //  fmtEl - fmt button element (optional)
  //  fmtImportEl - fmt "imports" checkbox element (optional)
  //  shareEl - share button element (optional)
  //  shareURLEl - share URL text input element (optional)
  //  shareRedirect - base URL to redirect to on share (optional)
  //  toysEl - toys select element (optional)
  //  enableHistory - enable using HTML5 history API (optional)
  //  transport - playground transport to use (default is HTTPTransport)
  //  enableShortcuts - whether to enable shortcuts (Ctrl+S/Cmd+S to save) (default is false)
  //  enableVet - enable running vet and displaying its errors
  function playground(opts) {
    var code = $(opts.codeEl);
    var transport = opts['transport'] || new HTTPTransport(opts['enableVet']);
    var running;

    // autoindent helpers.
    function insertTabs(n) {
      // find the selection start and end
      var start = code[0].selectionStart;
      var end = code[0].selectionEnd;
      // split the textarea content into two, and insert n tabs
      var v = code[0].value;
      var u = v.substr(0, start);
      for (var i = 0; i < n; i++) {
        u += '\t';
      }
      u += v.substr(end);
      // set revised content
      code[0].value = u;
      // reset caret position after inserted tabs
      code[0].selectionStart = start + n;
      code[0].selectionEnd = start + n;
    }
    function autoindent(el) {
      var curpos = el.selectionStart;
      var tabs = 0;
      while (curpos > 0) {
        curpos--;
        if (el.value[curpos] == '\t') {
          tabs++;
        } else if (tabs > 0 || el.value[curpos] == '\n') {
          break;
        }
      }
      setTimeout(function() {
        insertTabs(tabs);
      }, 1);
    }

    // NOTE(cbro): e is a jQuery event, not a DOM event.
    function handleSaveShortcut(e) {
      if (e.isDefaultPrevented()) return false;
      if (!e.metaKey && !e.ctrlKey) return false;
      if (e.key != 'S' && e.key != 's') return false;

      e.preventDefault();

      // Share and save
      share(function(url) {
        window.location.href = url + '.go?download=true';
      });

      return true;
    }

    function keyHandler(e) {
      if (opts.enableShortcuts && handleSaveShortcut(e)) return;

      if (e.keyCode == 9 && !e.ctrlKey) {
        // tab (but not ctrl-tab)
        insertTabs(1);
        e.preventDefault();
        return false;
      }
      if (e.keyCode == 13) {
        // enter
        if (e.shiftKey) {
          // +shift
          run();
          e.preventDefault();
          return false;
        }
        if (e.ctrlKey) {
          // +control
          fmt();
          e.preventDefault();
        } else {
          autoindent(e.target);
        }
      }
      return true;
    }
    code.unbind('keydown').bind('keydown', keyHandler);
    var outdiv = $(opts.outputEl).empty();
    var output = $('<pre/>').appendTo(outdiv);

    function body() {
      return $(opts.codeEl).val();
    }
    function setBody(text) {
      $(opts.codeEl).val(text);
    }
    function origin(href) {
      return ('' + href)
        .split('/')
        .slice(0, 3)
        .join('/');
    }

    var pushedEmpty = window.location.pathname == '/';
    function inputChanged() {
      if (pushedEmpty) {
        return;
      }
      pushedEmpty = true;
      $(opts.shareURLEl).hide();
      window.history.pushState(null, '', '/');
    }
    function popState(e) {
      if (e === null) {
        return;
      }
      if (e && e.state && e.state.code) {
        setBody(e.state.code);
      }
    }
    var rewriteHistory = false;
    if (
      window.history &&
      window.history.pushState &&
      window.addEventListener &&
      opts.enableHistory
    ) {
      rewriteHistory = true;
      code[0].addEventListener('input', inputChanged);
      window.addEventListener('popstate', popState);
    }

    function setError(error) {
      if (running) running.Kill();
      lineClear();
      lineHighlight(error);
      output
        .empty()
        .addClass('error')
        .text(error);
    }
    function loading() {
      lineClear();
      if (running) running.Kill();
      output.removeClass('error').text('Waiting for remote server...');
    }
    function run() {
      loading();
      running = transport.Run(
        body(),
        highlightOutput(PlaygroundOutput(output[0]))
      );
    }

    function fmt() {
      loading();
      var data = { body: body() };
      if ($(opts.fmtImportEl).is(':checked')) {
        data['imports'] = 'true';
      }
      $.ajax('/fmt', {
        data: data,
        type: 'POST',
        dataType: 'json',
        success: function(data) {
          if (data.Error) {
            setError(data.Error);
          } else {
            setBody(data.Body);
            setError('');
          }
        },
      });
    }

    var shareURL; // jQuery element to show the shared URL.
    var sharing = false; // true if there is a pending request.
    var shareCallbacks = [];
    function share(opt_callback) {
      if (opt_callback) shareCallbacks.push(opt_callback);

      if (sharing) return;
      sharing = true;

      var sharingData = body();
      $.ajax('https://play.golang.org/share', {
        processData: false,
        data: sharingData,
        type: 'POST',
        contentType: 'text/plain; charset=utf-8',
        complete: function(xhr) {
          sharing = false;
          if (xhr.status != 200) {
            alert('Server error; try again.');
            return;
          }
          if (opts.shareRedirect) {
            window.location = opts.shareRedirect + xhr.responseText;
          }
          var path = '/p/' + xhr.responseText;
          var url = origin(window.location) + path;

          for (var i = 0; i < shareCallbacks.length; i++) {
            shareCallbacks[i](url);
          }
          shareCallbacks = [];

          if (shareURL) {
            shareURL
              .show()
              .val(url)
              .focus()
              .select();

            if (rewriteHistory) {
              var historyData = { code: sharingData };
              window.history.pushState(historyData, '', path);
              pushedEmpty = false;
            }
          }
        },
      });
    }

    $(opts.runEl).click(run);
    $(opts.fmtEl).click(fmt);

    if (
      opts.shareEl !== null &&
      (opts.shareURLEl !== null || opts.shareRedirect !== null)
    ) {
      if (opts.shareURLEl) {
        shareURL = $(opts.shareURLEl).hide();
      }
      $(opts.shareEl).click(function() {
        share();
      });
    }

    if (opts.toysEl !== null) {
      $(opts.toysEl).bind('change', function() {
        var toy = $(this).val();
        $.ajax('/doc/play/' + toy, {
          processData: false,
          type: 'GET',
          complete: function(xhr) {
            if (xhr.status != 200) {
              alert('Server error; try again.');
              return;
            }
            setBody(xhr.responseText);
          },
        });
      });
    }
  }

  window.playground = playground;
})();


================================================
FILE: cmd/present/static/slides.js
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

var PERMANENT_URL_PREFIX = '/static/';

var SLIDE_CLASSES = ['far-past', 'past', 'current', 'next', 'far-next'];

var PM_TOUCH_SENSITIVITY = 15;

var curSlide;

/* ---------------------------------------------------------------------- */
/* classList polyfill by Eli Grey
 * (http://purl.eligrey.com/github/classList.js/blob/master/classList.js) */

if (
  typeof document !== 'undefined' &&
  !('classList' in document.createElement('a'))
) {
  (function(view) {
    var classListProp = 'classList',
      protoProp = 'prototype',
      elemCtrProto = (view.HTMLElement || view.Element)[protoProp],
      objCtr = Object;
    (strTrim =
      String[protoProp].trim ||
      function() {
        return this.replace(/^\s+|\s+$/g, '');
      }),
      (arrIndexOf =
        Array[protoProp].indexOf ||
        function(item) {
          for (var i = 0, len = this.length; i < len; i++) {
            if (i in this && this[i] === item) {
              return i;
            }
          }
          return -1;
        }),
      // Vendors: please allow content code to instantiate DOMExceptions
      (DOMEx = function(type, message) {
        this.name = type;
        this.code = DOMException[type];
        this.message = message;
      }),
      (checkTokenAndGetIndex = function(classList, token) {
        if (token === '') {
          throw new DOMEx(
            'SYNTAX_ERR',
            'An invalid or illegal string was specified'
          );
        }
        if (/\s/.test(token)) {
          throw new DOMEx(
            'INVALID_CHARACTER_ERR',
            'String contains an invalid character'
          );
        }
        return arrIndexOf.call(classList, token);
      }),
      (ClassList = function(elem) {
        var trimmedClasses = strTrim.call(elem.className),
          classes = trimmedClasses ? trimmedClasses.split(/\s+/) : [];
        for (var i = 0, len = classes.length; i < len; i++) {
          this.push(classes[i]);
        }
        this._updateClassName = function() {
          elem.className = this.toString();
        };
      }),
      (classListProto = ClassList[protoProp] = []),
      (classListGetter = function() {
        return new ClassList(this);
      });
    // Most DOMException implementations don't allow calling DOMException's toString()
    // on non-DOMExceptions. Error's toString() is sufficient here.
    DOMEx[protoProp] = Error[protoProp];
    classListProto.item = function(i) {
      return this[i] || null;
    };
    classListProto.contains = function(token) {
      token += '';
      return checkTokenAndGetIndex(this, token) !== -1;
    };
    classListProto.add = function(token) {
      token += '';
      if (checkTokenAndGetIndex(this, token) === -1) {
        this.push(token);
        this._updateClassName();
      }
    };
    classListProto.remove = function(token) {
      token += '';
      var index = checkTokenAndGetIndex(this, token);
      if (index !== -1) {
        this.splice(index, 1);
        this._updateClassName();
      }
    };
    classListProto.toggle = function(token) {
      token += '';
      if (checkTokenAndGetIndex(this, token) === -1) {
        this.add(token);
      } else {
        this.remove(token);
      }
    };
    classListProto.toString = function() {
      return this.join(' ');
    };

    if (objCtr.defineProperty) {
      var classListPropDesc = {
        get: classListGetter,
        enumerable: true,
        configurable: true,
      };
      try {
        objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
      } catch (ex) {
        // IE 8 doesn't support enumerable:true
        if (ex.number === -0x7ff5ec54) {
          classListPropDesc.enumerable = false;
          objCtr.defineProperty(elemCtrProto, classListProp, classListPropDesc);
        }
      }
    } else if (objCtr[protoProp].__defineGetter__) {
      elemCtrProto.__defineGetter__(classListProp, classListGetter);
    }
  })(self);
}
/* ---------------------------------------------------------------------- */

/* Slide movement */

function hideHelpText() {
  document.getElementById('help').style.display = 'none';
}

function getSlideEl(no) {
  if (no < 0 || no >= slideEls.length) {
    return null;
  } else {
    return slideEls[no];
  }
}

function updateSlideClass(slideNo, className) {
  var el = getSlideEl(slideNo);

  if (!el) {
    return;
  }

  if (className) {
    el.classList.add(className);
  }

  for (var i in SLIDE_CLASSES) {
    if (className != SLIDE_CLASSES[i]) {
      el.classList.remove(SLIDE_CLASSES[i]);
    }
  }
}

function updateSlides() {
  if (window.trackPageview) window.trackPageview();

  for (var i = 0; i < slideEls.length; i++) {
    switch (i) {
      case curSlide - 2:
        updateSlideClass(i, 'far-past');
        break;
      case curSlide - 1:
        updateSlideClass(i, 'past');
        break;
      case curSlide:
        updateSlideClass(i, 'current');
        break;
      case curSlide + 1:
        updateSlideClass(i, 'next');
        break;
      case curSlide + 2:
        updateSlideClass(i, 'far-next');
        break;
      default:
        updateSlideClass(i);
        break;
    }
  }

  triggerLeaveEvent(curSlide - 1);
  triggerEnterEvent(curSlide);

  window.setTimeout(function() {
    // Hide after the slide
    disableSlideFrames(curSlide - 2);
  }, 301);

  enableSlideFrames(curSlide - 1);
  enableSlideFrames(curSlide + 2);

  updateHash();
}

function prevSlide() {
  hideHelpText();
  if (curSlide > 0) {
    curSlide--;

    updateSlides();
  }

  if (notesEnabled) localStorage.setItem(destSlideKey(), curSlide);
}

function nextSlide() {
  hideHelpText();
  if (curSlide < slideEls.length - 1) {
    curSlide++;

    updateSlides();
  }

  if (notesEnabled) localStorage.setItem(destSlideKey(), curSlide);
}

/* Slide events */

function triggerEnterEvent(no) {
  var el = getSlideEl(no);
  if (!el) {
    return;
  }

  var onEnter = el.getAttribute('onslideenter');
  if (onEnter) {
    new Function(onEnter).call(el);
  }

  var evt = document.createEvent('Event');
  evt.initEvent('slideenter', true, true);
  evt.slideNumber = no + 1; // Make it readable

  el.dispatchEvent(evt);
}

function triggerLeaveEvent(no) {
  var el = getSlideEl(no);
  if (!el) {
    return;
  }

  var onLeave = el.getAttribute('onslideleave');
  if (onLeave) {
    new Function(onLeave).call(el);
  }

  var evt = document.createEvent('Event');
  evt.initEvent('slideleave', true, true);
  evt.slideNumber = no + 1; // Make it readable

  el.dispatchEvent(evt);
}

/* Touch events */

function handleTouchStart(event) {
  if (event.touches.length == 1) {
    touchDX = 0;
    touchDY = 0;

    touchStartX = event.touches[0].pageX;
    touchStartY = event.touches[0].pageY;

    document.body.addEventListener('touchmove', handleTouchMove, true);
    document.body.addEventListener('touchend', handleTouchEnd, true);
  }
}

function handleTouchMove(event) {
  if (event.touches.length > 1) {
    cancelTouch();
  } else {
    touchDX = event.touches[0].pageX - touchStartX;
    touchDY = event.touches[0].pageY - touchStartY;
    event.preventDefault();
  }
}

function handleTouchEnd(event) {
  var dx = Math.abs(touchDX);
  var dy = Math.abs(touchDY);

  if (dx > PM_TOUCH_SENSITIVITY && dy < (dx * 2) / 3) {
    if (touchDX > 0) {
      prevSlide();
    } else {
      nextSlide();
    }
  }

  cancelTouch();
}

function cancelTouch() {
  document.body.removeEventListener('touchmove', handleTouchMove, true);
  document.body.removeEventListener('touchend', handleTouchEnd, true);
}

/* Preloading frames */

function disableSlideFrames(no) {
  var el = getSlideEl(no);
  if (!el) {
    return;
  }

  var frames = el.getElementsByTagName('iframe');
  for (var i = 0, frame; (frame = frames[i]); i++) {
    disableFrame(frame);
  }
}

function enableSlideFrames(no) {
  var el = getSlideEl(no);
  if (!el) {
    return;
  }

  var frames = el.getElementsByTagName('iframe');
  for (var i = 0, frame; (frame = frames[i]); i++) {
    enableFrame(frame);
  }
}

function disableFrame(frame) {
  frame.src = 'about:blank';
}

function enableFrame(frame) {
  var src = frame._src;

  if (frame.src != src && src != 'about:blank') {
    frame.src = src;
  }
}

function setupFrames() {
  var frames = document.querySelectorAll('iframe');
  for (var i = 0, frame; (frame = frames[i]); i++) {
    frame._src = frame.src;
    disableFrame(frame);
  }

  enableSlideFrames(curSlide);
  enableSlideFrames(curSlide + 1);
  enableSlideFrames(curSlide + 2);
}

function setupInteraction() {
  /* Clicking and tapping */

  var el = document.createElement('div');
  el.className = 'slide-area';
  el.id = 'prev-slide-area';
  el.addEventListener('click', prevSlide, false);
  document.querySelector('section.slides').appendChild(el);

  var el = document.createElement('div');
  el.className = 'slide-area';
  el.id = 'next-slide-area';
  el.addEventListener('click', nextSlide, false);
  document.querySelector('section.slides').appendChild(el);

  /* Swiping */

  document.body.addEventListener('touchstart', handleTouchStart, false);
}

/* Hash functions */

function getCurSlideFromHash() {
  var slideNo = parseInt(location.hash.substr(1));

  if (slideNo) {
    curSlide = slideNo - 1;
  } else {
    curSlide = 0;
  }
}

function updateHash() {
  location.replace('#' + (curSlide + 1));
}

/* Event listeners */

function handleBodyKeyDown(event) {
  // If we're in a code element, only handle pgup/down.
  var inCode = event.target.classList.contains('code');

  switch (event.keyCode) {
    case 78: // 'N' opens presenter notes window
      if (!inCode && notesEnabled) toggleNotesWindow();
      break;
    case 72: // 'H' hides the help text
    case 27: // escape key
      if (!inCode) hideHelpText();
      break;

    case 39: // right arrow
    case 13: // Enter
    case 32: // space
      if (inCode) break;
    case 34: // PgDn
      nextSlide();
      event.preventDefault();
      break;

    case 37: // left arrow
    case 8: // Backspace
      if (inCode) break;
    case 33: // PgUp
      prevSlide();
      event.preventDefault();
      break;

    case 40: // down arrow
      if (inCode) break;
      nextSlide();
      event.preventDefault();
      break;

    case 38: // up arrow
      if (inCode) break;
      prevSlide();
      event.preventDefault();
      break;
  }
}

function scaleSmallViewports() {
  var el = document.querySelector('section.slides');
  var transform = '';
  var sWidthPx = 1250;
  var sHeightPx = 750;
  var sAspectRatio = sWidthPx / sHeightPx;
  var wAspectRatio = window.innerWidth / window.innerHeight;

  if (wAspectRatio <= sAspectRatio && window.innerWidth < sWidthPx) {
    transform = 'scale(' + window.innerWidth / sWidthPx + ')';
  } else if (window.innerHeight < sHeightPx) {
    transform = 'scale(' + window.innerHeight / sHeightPx + ')';
  }
  el.style.transform = transform;
}

function addEventListeners() {
  document.addEventListener('keydown', handleBodyKeyDown, false);
  var resizeTimeout;
  window.addEventListener('resize', function() {
    // throttle resize events
    window.clearTimeout(resizeTimeout);
    resizeTimeout = window.setTimeout(function() {
      resizeTimeout = null;
      scaleSmallViewports();
    }, 50);
  });

  // Force reset transform property of section.slides when printing page.
  // Use both onbeforeprint and matchMedia for compatibility with different browsers.
  var beforePrint = function() {
    var el = document.querySelector('section.slides');
    el.style.transform = '';
  };
  window.onbeforeprint = beforePrint;
  if (window.matchMedia) {
    var mediaQueryList = window.matchMedia('print');
    mediaQueryList.addListener(function(mql) {
      if (mql.matches) beforePrint();
    });
  }
}

/* Initialization */

function addFontStyle() {
  var el = document.createElement('link');
  el.rel = 'stylesheet';
  el.type = 'text/css';
  el.href =
    '//fonts.googleapis.com/css?family=' +
    'Open+Sans:regular,semibold,italic,italicsemibold|Droid+Sans+Mono';

  document.body.appendChild(el);
}

function addGeneralStyle() {
  var el = document.createElement('link');
  el.rel = 'stylesheet';
  el.type = 'text/css';
  el.href = PERMANENT_URL_PREFIX + 'styles.css';
  document.body.appendChild(el);

  var el = document.createElement('meta');
  el.name = 'viewport';
  el.content = 'width=device-width,height=device-height,initial-scale=1';
  document.querySelector('head').appendChild(el);

  var el = document.createElement('meta');
  el.name = 'apple-mobile-web-app-capable';
  el.content = 'yes';
  document.querySelector('head').appendChild(el);

  scaleSmallViewports();
}

function handleDomLoaded() {
  slideEls = document.querySelectorAll('section.slides > article');

  setupFrames();

  addFontStyle();
  addGeneralStyle();
  addEventListeners();

  updateSlides();

  setupInteraction();

  if (
    window.location.hostname == 'localhost' ||
    window.location.hostname == '127.0.0.1' ||
    window.location.hostname == '::1'
  ) {
    hideHelpText();
  }

  document.body.classList.add('loaded');

  setupNotesSync();
}

function initialize() {
  getCurSlideFromHash();

  if (window['_DEBUG']) {
    PERMANENT_URL_PREFIX = '../';
  }

  if (window['_DCL']) {
    handleDomLoaded();
  } else {
    document.addEventListener('DOMContentLoaded', handleDomLoaded, false);
  }
}

// If ?debug exists then load the script relative instead of absolute
if (!window['_DEBUG'] && document.location.href.indexOf('?debug') !== -1) {
  document.addEventListener(
    'DOMContentLoaded',
    function() {
      // Avoid missing the DomContentLoaded event
      window['_DCL'] = true;
    },
    false
  );

  window['_DEBUG'] = true;
  var script = document.createElement('script');
  script.type = 'text/javascript';
  script.src = '../slides.js';
  var s = document.getElementsByTagName('script')[0];
  s.parentNode.insertBefore(script, s);

  // Remove this script
  s.parentNode.removeChild(s);
} else {
  initialize();
}

/* Synchronize windows when notes are enabled */

function setupNotesSync() {
  if (!notesEnabled) return;

  function setupPlayResizeSync() {
    var out = document.getElementsByClassName('output');
    for (var i = 0; i < out.length; i++) {
      $(out[i]).bind('resize', function(event) {
        if ($(event.target).hasClass('ui-resizable')) {
          localStorage.setItem('play-index', i);
          localStorage.setItem('output-style', out[i].style.cssText);
        }
      });
    }
  }
  function setupPlayCodeSync() {
    var play = document.querySelectorAll('div.playground');
    for (var i = 0; i < play.length; i++) {
      play[i].addEventListener('input', inputHandler, false);

      function inputHandler(e) {
        localStorage.setItem('play-index', i);
        localStorage.setItem('play-code', e.target.innerHTML);
      }
    }
  }

  setupPlayCodeSync();
  setupPlayResizeSync();
  localStorage.setItem(destSlideKey(), curSlide);
  window.addEventListener('storage', updateOtherWindow, false);
}

// An update to local storage is caught only by the other window
// The triggering window does not handle any sync actions
function updateOtherWindow(e) {
  // Ignore remove storage events which are not meant to update the other window
  var isRemoveStorageEvent = !e.newValue;
  if (isRemoveStorageEvent) return;

  var destSlide = localStorage.getItem(destSlideKey());
  while (destSlide > curSlide) {
    nextSlide();
  }
  while (destSlide < curSlide) {
    prevSlide();
  }

  updatePlay(e);
  updateNotes();
}


================================================
FILE: cmd/present/static/styles.css
================================================
@media screen {
  /* Framework */
  html {
    height: 100%;
  }

  body {
    margin: 0;
    padding: 0;

    display: block !important;

    height: 100%;
    height: 100vh;

    overflow: hidden;

    background: rgb(215, 215, 215);
    background: -o-radial-gradient(rgb(240, 240, 240), rgb(190, 190, 190));
    background: -moz-radial-gradient(rgb(240, 240, 240), rgb(190, 190, 190));
    background: -webkit-radial-gradient(rgb(240, 240, 240), rgb(190, 190, 190));
    background: -webkit-gradient(
      radial,
      50% 50%,
      0,
      50% 50%,
      500,
      from(rgb(240, 240, 240)),
      to(rgb(190, 190, 190))
    );

    -webkit-font-smoothing: antialiased;
  }

  .slides {
    width: 100%;
    height: 100%;
    left: 0;
    top: 0;

    position: absolute;

    -webkit-transform: translate3d(0, 0, 0);
  }

  .slides > article {
    display: block;

    position: absolute;
    overflow: hidden;

    width: 900px;
    height: 700px;

    left: 50%;
    top: 50%;

    margin-left: -450px;
    margin-top: -350px;

    padding: 40px 60px;

    box-sizing: border-box;
    -o-box-sizing: border-box;
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;

    border-radius: 10px;
    -o-border-radius: 10px;
    -moz-border-radius: 10px;
    -webkit-border-radius: 10px;

    background-color: white;

    border: 1px solid rgba(0, 0, 0, 0.3);

    transition: transform 0.3s ease-out;
    -o-transition: -o-transform 0.3s ease-out;
    -moz-transition: -moz-transform 0.3s ease-out;
    -webkit-transition: -webkit-transform 0.3s ease-out;
  }
  .slides.layout-widescreen > article {
    margin-left: -550px;
    width: 1100px;
  }
  .slides.layout-faux-widescreen > article {
    margin-left: -550px;
    width: 1100px;

    padding: 40px 160px;
  }

  .slides.layout-widescreen > article:not(.nobackground):not(.biglogo),
  .slides.layout-faux-widescreen > article:not(.nobackground):not(.biglogo) {
    background-position-x: 0, 840px;
  }

  /* Clickable/tappable areas */

  .slide-area {
    z-index: 1000;

    position: absolute;
    left: 0;
    top: 0;
    width: 150px;
    height: 700px;

    left: 50%;
    top: 50%;

    cursor: pointer;
    margin-top: -350px;

    tap-highlight-color: transparent;
    -o-tap-highlight-color: transparent;
    -moz-tap-highlight-color: transparent;
    -webkit-tap-highlight-color: transparent;
  }
  #prev-slide-area {
    margin-left: -550px;
  }
  #next-slide-area {
    margin-left: 400px;
  }
  .slides.layout-widescreen #prev-slide-area,
  .slides.layout-faux-widescreen #prev-slide-area {
    margin-left: -650px;
  }
  .slides.layout-widescreen #next-slide-area,
  .slides.layout-faux-widescreen #next-slide-area {
    margin-left: 500px;
  }

  /* Slides */

  .slides > article {
    display: none;
  }
  .slides > article.far-past {
    display: block;
    transform: translate(-2040px);
    -o-transform: translate(-2040px);
    -moz-transform: translate(-2040px);
    -webkit-transform: translate3d(-2040px, 0, 0);
  }
  .slides > article.past {
    display: block;
    transform: translate(-1020px);
    -o-transform: translate(-1020px);
    -moz-transform: translate(-1020px);
    -webkit-transform: translate3d(-1020px, 0, 0);
  }
  .slides > article.current {
    display: block;
    transform: translate(0);
    -o-transform: translate(0);
    -moz-transform: translate(0);
    -webkit-transform: translate3d(0, 0, 0);
  }
  .slides > article.next {
    display: block;
    transform: translate(1020px);
    -o-transform: translate(1020px);
    -moz-transform: translate(1020px);
    -webkit-transform: translate3d(1020px, 0, 0);
  }
  .slides > article.far-next {
    display: block;
    transform: translate(2040px);
    -o-transform: translate(2040px);
    -moz-transform: translate(2040px);
    -webkit-transform: translate3d(2040px, 0, 0);
  }

  .slides.layout-widescreen > article.far-past,
  .slides.layout-faux-widescreen > article.far-past {
    display: block;
    transform: translate(-2260px);
    -o-transform: translate(-2260px);
    -moz-transform: translate(-2260px);
    -webkit-transform: translate3d(-2260px, 0, 0);
  }
  .slides.layout-widescreen > article.past,
  .slides.layout-faux-widescreen > article.past {
    display: block;
    transform: translate(-1130px);
    -o-transform: translate(-1130px);
    -moz-transform: translate(-1130px);
    -webkit-transform: translate3d(-1130px, 0, 0);
  }
  .slides.layout-widescreen > article.current,
  .slides.layout-faux-widescreen > article.current {
    display: block;
    transform: translate(0);
    -o-transform: translate(0);
    -moz-transform: translate(0);
    -webkit-transform: translate3d(0, 0, 0);
  }
  .slides.layout-widescreen > article.next,
  .slides.layout-faux-widescreen > article.next {
    display: block;
    transform: translate(1130px);
    -o-transform: translate(1130px);
    -moz-transform: translate(1130px);
    -webkit-transform: translate3d(1130px, 0, 0);
  }
  .slides.layout-widescreen > article.far-next,
  .slides.layout-faux-widescreen > article.far-next {
    display: block;
    transform: translate(2260px);
    -o-transform: translate(2260px);
    -moz-transform: translate(2260px);
    -webkit-transform: translate3d(2260px, 0, 0);
  }
}

@media print {
  /* Set page layout */
  @page {
    size: A4 landscape;
  }

  body {
    display: block !important;
  }

  .slides > article {
    display: block;

    position: relative;

    page-break-inside: never;
    page-break-after: always;

    overflow: hidden;
  }

  h2 {
    position: static !important;
    margin-top: 400px !important;
    margin-bottom: 100px !important;
  }

  pre {
    background: rgb(240, 240, 240);
  }

  /* Add explicit links */
  a:link:after,
  a:visited:after {
    content: ' (' attr(href) ') ';
    font-size: 50%;
  }

  #help {
    display: none;
    visibility: hidden;
  }
}

/* Styles for slides */

.slides > article {
  font-family: 'Open Sans', Arial, sans-serif;

  color: black;
  text-shadow: 0 1px 1px rgba(0, 0, 0, 0.1);

  font-size: 26px;
  line-height: 36px;

  letter-spacing: -1px;
}

b {
  font-weight: 600;
}

a {
  color: rgb(0, 102, 204);
  text-decoration: none;
}
a:visited {
  color: rgba(0, 102, 204, 0.75);
}
a:hover {
  color: black;
}

p {
  margin: 0;
  padding: 0;

  margin-top: 20px;
}
p:first-child {
  margin-top: 0;
}

h1 {
  font-size: 60px;
  line-height: 60px;

  padding: 0;
  margin: 0;
  margin-top: 200px;
  margin-bottom: 5px;
  padding-right: 40px;

  font-weight: 600;

  letter-spacing: -3px;

  color: rgb(51, 51, 51);
}

h2 {
  font-size: 45px;
  line-height: 45px;

  position: absolute;
  bottom: 150px;

  padding: 0;
  margin: 0;
  padding-right: 40px;

  font-weight: 600;

  letter-spacing: -2px;

  color: rgb(51, 51, 51);
}

h3 {
  font-size: 30px;
  line-height: 36px;

  padding: 0;
  margin: 0;
  padding-right: 40px;

  font-weight: 600;

  letter-spacing: -1px;

  color: rgb(51, 51, 51);
}

ul {
  margin: 0;
  padding: 0;
  margin-top: 20px;
  margin-left: 1.5em;
}
li {
  padding: 0;
  margin: 0 0 0.5em 0;
}

div.code, div.output {
  margin: 0;
  padding: 0;
}

pre {
  padding: 5px 10px;
  margin-top: 20px;
  margin-bottom: 20px;
  overflow: hidden;

  background: rgb(240, 240, 240);
  border: 1px solid rgb(224, 224, 224);

  font-family: 'Droid Sans Mono', 'Courier New', monospace;
  font-size: 18px;
  line-height: 24px;
  letter-spacing: -1px;

  color: black;
}

pre.numbers span:before {
  content: attr(num);
  margin-right: 1em;
  display: inline-block;
}

code {
  font-size: 95%;
  font-family: 'Droid Sans Mono', 'Courier New', monospace;

  color: black;
}

pre code {
  font-size: 100%;
}

article > .image,
article > .video {
  text-align: center;
  margin-top: 40px;
}

article.background {
  background-size: contain;
  background-repeat: round;
}

table {
  width: 100%;
  border-collapse: collapse;
  margin-top: 40px;
}
th {
  font-weight: 600;
  text-align: left;
}
td,
th {
  border: 1px solid rgb(224, 224, 224);
  padding: 5px 10px;
  vertical-align: top;
}

p.link {
  margin-left: 20px;
}

.pagenumber {
  color: #8c8c8c;
  font-size: 75%;
  position: absolute;
  bottom: 0px;
  right: 10px;
}

/* Code */
pre {
  outline: 0px solid transparent;
}
div.playground {
  position: relative;
}
div.output {
  position: absolute;
  left: 50%;
  top: 50%;
  right: 40px;
  bottom: 40px;
  background: #202020;
  padding: 5px 10px;
  z-index: 2;

  border-radius: 10px;
  -o-border-radius: 10px;
  -moz-border-radius: 10px;
  -webkit-border-radius: 10px;
}
div.output pre {
  margin: 0;
  padding: 0;
  background: none;
  border: none;
  width: 100%;
  height: 100%;
  overflow: auto;
}
div.output .stdout,
div.output pre {
  color: #e6e6e6;
}
div.output .stderr,
div.output .error {
  color: rgb(255, 200, 200);
}
div.output .system,
div.output .exit {
  color: rgb(255, 230, 120);
}
.buttons {
  position: relative;
  float: right;
  top: -60px;
  right: 10px;
}
div.output .buttons {
  position: absolute;
  float: none;
  top: auto;
  right: 5px;
  bottom: 5px;
}

/* Presenter details */
.presenter {
  margin-top: 20px;
}
.presenter p,
.presenter .link {
  margin: 0;
  font-size: 28px;
  line-height: 1.2em;
}

/* Output resize details */
.ui-resizable-handle {
  position: absolute;
}
.ui-resizable-n {
  cursor: n-resize;
  height: 7px;
  width: 100%;
  top: -5px;
  left: 0;
}
.ui-resizable-w {
  cursor: w-resize;
  width: 7px;
  left: -5px;
  top: 0;
  height: 100%;
}
.ui-resizable-nw {
  cursor: nw-resize;
  width: 9px;
  height: 9px;
  left: -5px;
  top: -5px;
}
iframe {
  border: none;
}
figcaption {
  color: #666;
  text-align: center;
  font-size: 0.75em;
}

#help {
  font-family: 'Open Sans', Arial, sans-serif;
  text-align: center;
  color: white;
  background: #000;
  opacity: 0.5;
  position: fixed;
  bottom: 25px;
  left: 50px;
  right: 50px;
  padding: 20px;

  border-radius: 10px;
  -o-border-radius: 10px;
  -moz-border-radius: 10px;
  -webkit-border-radius: 10px;
}


================================================
FILE: cmd/present/templates/action.tmpl
================================================
{/*
This is the action template.
It determines how the formatting actions are rendered.
*/}

{{define "section"}}
  <h{{len .Number}} id="TOC_{{.FormattedNumber}}">{{.FormattedNumber}} {{.Title}}</h{{len .Number}}>
  {{range .Elem}}{{elem $.Template .}}{{end}}
{{end}}

{{define "list"}}
  <ul>
  {{range .Bullet}}
    <li>{{style .}}</li>
  {{end}}
  </ul>
{{end}}

{{define "text"}}
  {{if .Pre}}
  <div class="code"><pre>{{range .Lines}}{{.}}{{end}}</pre></div>
  {{else}}
  <p>
    {{range $i, $l := .Lines}}{{if $i}}{{template "newline"}}
    {{end}}{{style $l}}{{end}}
  </p>
  {{end}}
{{end}}

{{define "code"}}
  <div class="code{{if playable .}} playground{{end}}" {{if .Edit}}contenteditable="true" spellcheck="false"{{end}}>{{.Text}}</div>
{{end}}

{{define "image"}}
<div class="image">
  <img src="{{.URL}}"{{with .Height}} height="{{.}}"{{end}}{{with .Width}} width="{{.}}"{{end}}>
</div>
{{end}}

{{define "video"}}
<div class="video">
  <video {{with .Height}} height="{{.}}"{{end}}{{with .Width}} width="{{.}}"{{end}} controls>
    <source src="{{.URL}}" type="{{.SourceType}}">
  </video>
</div>
{{end}}

{{define "background"}}
<div class="background">
  <img src="{{.URL}}">
</div>
{{end}}

{{define "iframe"}}
<iframe src="{{.URL}}"{{with .Height}} height="{{.}}"{{end}}{{with .Width}} width="{{.}}"{{end}}></iframe>
{{end}}

{{define "link"}}<p class="link"><a href="{{.URL}}" target="_blank">{{style .Label}}</a></p>{{end}}

{{define "html"}}{{.HTML}}{{end}}

{{define "caption"}}<figcaption>{{style .Text}}</figcaption>{{end}}


================================================
FILE: cmd/present/templates/article.tmpl
================================================
{/* This is the article template. It defines how articles are formatted. */}

{{define "root"}}
<!DOCTYPE html>
<html>
  <head>
    <title>{{.Title}}</title>
    <link type="text/css" rel="stylesheet" href="/static/article.css">
    <meta charset='utf-8'>
    <script>
      // Initialize Google Analytics tracking code on production site only.
      if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
        var _gaq = _gaq || [];
        _gaq.push(["_setAccount", "UA-11222381-6"]);
        _gaq.push(["b._setAccount", "UA-49880327-6"]);
        window.trackPageview = function() {
          _gaq.push(["_trackPageview", location.pathname+location.hash]);
          _gaq.push(["b._trackPageview", location.pathname+location.hash]);
        };
        window.trackPageview();
        window.trackEvent = function(category, action, opt_label, opt_value, opt_noninteraction) {
          _gaq.push(["_trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
          _gaq.push(["b._trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
        };
      }
    </script>
  </head>

  <body>
    <div id="topbar" class="wide">
      <div class="container">
        <div id="heading">{{.Title}}
          {{with .Subtitle}}{{.}}{{end}}
          {{if .Authors}}
            {{range .Authors}}
              <div class="author">
                {{range .Elem}}{{elem $.Template .}}{{end}}
              </div>
            {{end}}
          {{end}}
        </div>
      </div>
    </div>
    <div id="page" class="wide">
      <div class="container">
        {{with .Sections}}
          <div id="toc" class="no-print">
            <div id="tochead">Contents</div>
            {{template "TOC" .}}
          </div>
        {{end}}

        {{range .Sections}}
          {{elem $.Template .}}
        {{end}}{{/* of Section block */}}

      </div>
    </div>

    {{if .PlayEnabled}}
    <script src='/play.js'></script>
    {{end}}

    <script>
      (function() {
        // Load Google Analytics tracking code on production site only.
        if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
          var ga = document.createElement("script"); ga.type = "text/javascript"; ga.async = true;
          ga.src = ("https:" == document.location.protocol ? "https://ssl" : "http://www") + ".google-analytics.com/ga.js";
          var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(ga, s);
        }
      })();
    </script>
  </body>
</html>
{{end}}

{{define "TOC"}}
  <ul class="toc-outer">
  {{range .}}
    <li><a href="#TOC_{{.FormattedNumber}}">{{.Title}}</a></li>
    {{with .Sections}}{{template "TOC-Inner" .}}{{end}}
  {{end}}
  </ul>
{{end}}

{{define "TOC-Inner"}}
  <ul class="toc-inner">
  {{range .}}
    <li><a href="#TOC_{{.FormattedNumber}}">{{.Title}}</a></li>
    {{with .Sections}}{{template "TOC-Inner" .}}{{end}}
  {{end}}
  </ul>
{{end}}

{{define "newline"}}
{{/* No automatic line break. Paragraphs are free-form. */}}
{{end}}


================================================
FILE: cmd/present/templates/dir.tmpl
================================================
<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <title>Talks - The Go Programming Language</title>
  <link type="text/css" rel="stylesheet" href="/static/dir.css">
  <script src="/static/dir.js"></script>
  <script>
    // Initialize Google Analytics tracking code on production site only.
    if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
      var _gaq = _gaq || [];
      _gaq.push(["_setAccount", "UA-11222381-6"]);
      _gaq.push(["b._setAccount", "UA-49880327-6"]);
      window.trackPageview = function() {
        _gaq.push(["_trackPageview", location.pathname+location.hash]);
        _gaq.push(["b._trackPageview", location.pathname+location.hash]);
      };
      window.trackPageview();
      window.trackEvent = function(category, action, opt_label, opt_value, opt_noninteraction) {
        _gaq.push(["_trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
        _gaq.push(["b._trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
      };
    }
  </script>
</head>
<body>

<div id="topbar"><div class="container">

<form method="GET" action="//golang.org/search">
<div id="menu">
<a href="http://golang.org/doc/">Documents</a>
<a href="http://golang.org/ref">References</a>
<a href="http://golang.org/pkg/">Packages</a>
<a href="http://golang.org/project/">The Project</a>
<a href="http://golang.org/help/">Help</a>
<input type="text" id="search" name="q" class="inactive" value="Search">
</div>
<div id="heading"><a href="/">The Go Programming Language</a></div>
</form>

</div></div>

<div id="page">

  <h1>Go talks</h1>

  {{with .Path}}<h2>{{.}}</h2>{{end}}

  {{with .Articles}}
  <h4>Articles:</h4>
  <dl>
  {{range .}}
  <dd><a href="/{{.Path}}">{{.Name}}</a>: {{.Title}}</dd>
  {{end}}
  </dl>
  {{end}}

  {{with .Slides}}
  <h4>Slide decks:</h4>
  <dl>
  {{range .}}
  <dd><a href="/{{.Path}}">{{.Name}}</a>: {{.Title}}</dd>
  {{end}}
  </dl>
  {{end}}

  {{with .Other}}
  <h4>Files:</h4>
  <dl>
  {{range .}}
  <dd><a href="/{{.Path}}">{{.Name}}</a></dd>
  {{end}}
  </dl>
  {{end}}

  {{with .Dirs}}
  <h4>Sub-directories:</h4>
  <dl>
  {{range .}}
  <dd><a href="/{{.Path}}">{{.Name}}</a></dd>
  {{end}}
  </dl>
  {{end}}

</div>

<div id="footer">
Except as <a href="https://developers.google.com/site-policies#restrictions">noted</a>,
the content of this page is licensed under the
Creative Commons Attribution 3.0 License,
and code is licensed under a <a href="http://golang.org/LICENSE">BSD license</a>.<br>
<a href="http://golang.org/doc/tos.html">Terms of Service</a> |
<a href="http://www.google.com/intl/en/policies/privacy/">Privacy Policy</a>
</div>

<script>
  (function() {
    // Load Google Analytics tracking code on production site only.
    if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
      var ga = document.createElement("script"); ga.type = "text/javascript"; ga.async = true;
      ga.src = ("https:" == document.location.protocol ? "https://ssl" : "http://www") + ".google-analytics.com/ga.js";
      var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(ga, s);
    }
  })();
</script>
</body>
</html>


================================================
FILE: cmd/present/templates/slides.tmpl
================================================
{/* This is the slide template. It defines how presentations are formatted. */}

{{define "root"}}
<!DOCTYPE html>
<html>
  <head>
    <title>{{.Title}}</title>
    <meta charset='utf-8'>
    <script>
      var notesEnabled = {{.NotesEnabled}};
    </script>
    <script src='/static/slides.js'></script>

    {{if .NotesEnabled}}
    <script>
      var sections = {{.Sections}};
      var titleNotes = {{.TitleNotes}}
    </script>
    <script src='/static/notes.js'></script>
    {{end}}

    <script>
      // Initialize Google Analytics tracking code on production site only.
      if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
        var _gaq = _gaq || [];
        _gaq.push(["_setAccount", "UA-11222381-6"]);
        _gaq.push(["b._setAccount", "UA-49880327-6"]);
        window.trackPageview = function() {
          _gaq.push(["_trackPageview", location.pathname+location.hash]);
          _gaq.push(["b._trackPageview", location.pathname+location.hash]);
        };
        window.trackPageview();
        window.trackEvent = function(category, action, opt_label, opt_value, opt_noninteraction) {
          _gaq.push(["_trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
          _gaq.push(["b._trackEvent", category, action, opt_label, opt_value, opt_noninteraction]);
        };
      }
    </script>
  </head>

  <body style='display: none'>

    <section class='slides layout-widescreen'>

      <article>
        <h1>{{.Title}}</h1>
        {{with .Subtitle}}<h3>{{.}}</h3>{{end}}
        {{if not .Time.IsZero}}<h3>{{.Time.Format "2 January 2006"}}</h3>{{end}}
        {{range .Authors}}
          <div class="presenter">
            {{range .TextElem}}{{elem $.Template .}}{{end}}
          </div>
        {{end}}
      </article>

  {{range $i, $s := .Sections}}
  <!-- start of slide {{$s.Number}} -->
      <article {{$s.HTMLAttributes}}>
      {{if $s.Elem}}
        <h3>{{$s.Title}}</h3>
        {{range $s.Elem}}{{elem $.Template .}}{{end}}
      {{else}}
        <h2>{{$s.Title}}</h2>
      {{end}}
      <span class="pagenumber">{{pagenum $s 1}}</span>
      </article>
  <!-- end of slide {{$s.Number}} -->
  {{end}}{{/* of Slide block */}}

      <article>
        <h3>Thank you</h3>
        {{range .Authors}}
          <div class="presenter">
            {{range .Elem}}{{elem $.Template .}}{{end}}
          </div>
        {{end}}
      </article>

    </section>

    <div id="help">
      Use the left and right arrow keys or click the left and right
      edges of the page to navigate between slides.<br>
      (Press 'H' or navigate to hide this message.)
    </div>

    {{if .PlayEnabled}}
    <script src='/play.js'></script>
    {{end}}

    <script>
      (function() {
        // Load Google Analytics tracking code on production site only.
        if (window["location"] && window["location"]["hostname"] == "talks.golang.org") {
          var ga = document.createElement("script"); ga.type = "text/javascript"; ga.async = true;
          ga.src = ("https:" == document.location.protocol ? "https://ssl" : "http://www") + ".google-analytics.com/ga.js";
          var s = document.getElementsByTagName("script")[0]; s.parentNode.insertBefore(ga, s);
        }
      })();
    </script>
  </body>
</html>
{{end}}

{{define "newline"}}
<br>
{{end}}


================================================
FILE: cmd/present2md/main.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Present2md converts legacy-syntax present files to Markdown-syntax present files.
//
// Usage:
//
//	present2md [-w] [file ...]
//
// By default, present2md prints the Markdown-syntax form of each input file to standard output.
// If no input file is listed, standard input is used.
//
// The -w flag causes present2md to update the files in place, overwriting each with its
// Markdown-syntax equivalent.
//
// Examples
//
//	present2md your.article
//	present2md -w *.article
package main

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"log"
	"net/url"
	"os"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/present"
)

func usage() {
	fmt.Fprintf(os.Stderr, "usage: present2md [-w] [file ...]\n")
	os.Exit(2)
}

var (
	writeBack  = flag.Bool("w", false, "write conversions back to original files")
	exitStatus = 0
)

func main() {
	log.SetPrefix("present2md: ")
	log.SetFlags(0)
	flag.Usage = usage
	flag.Parse()

	args := flag.Args()
	if len(args) == 0 {
		if *writeBack {
			log.Fatalf("cannot use -w with standard input")
		}
		convert(os.Stdin, "stdin", false)
		return
	}

	for _, arg := range args {
		f, err := os.Open(arg)
		if err != nil {
			log.Print(err)
			exitStatus = 1
			continue
		}
		err = convert(f, arg, *writeBack)
		f.Close()
		if err != nil {
			log.Print(err)
			exitStatus = 1
		}
	}
	os.Exit(exitStatus)
}

// convert reads the data from r, parses it as legacy present,
// and converts it to Markdown-enabled present.
// If any errors occur, the data is reported as coming from file.
// If writeBack is true, the converted version is written back to file.
// If writeBack is false, the converted version is printed to standard output.
func convert(r io.Reader, file string, writeBack bool) error {
	data, err := io.ReadAll(r)
	if err != nil {
		return err
	}
	if bytes.HasPrefix(data, []byte("# ")) {
		return fmt.Errorf("%v: already markdown", file)
	}

	// Convert all comments before parsing the document.
	// The '//' comment is treated as normal text and so
	// is passed through the translation unaltered.
	data = bytes.Replace(data, []byte("\n#"), []byte("\n//"), -1)

	doc, err := present.Parse(bytes.NewReader(data), file, 0)
	if err != nil {
		return err
	}

	// Title and Subtitle, Time, Tags.
	var md bytes.Buffer
	fmt.Fprintf(&md, "# %s\n", doc.Title)
	if doc.Subtitle != "" {
		fmt.Fprintf(&md, "%s\n", doc.Subtitle)
	}
	if !doc.Time.IsZero() {
		fmt.Fprintf(&md, "%s\n", doc.Time.Format("2 Jan 2006"))
	}
	if len(doc.Tags) > 0 {
		fmt.Fprintf(&md, "Tags: %s\n", strings.Join(doc.Tags, ", "))
	}

	// Summary, defaulting to first paragraph of section.
	// (Summaries must be explicit for Markdown-enabled present,
	// and the expectation is that they will be shorter than the
	// whole first paragraph. But this is what the blog does today.)
	if strings.HasSuffix(file, ".article") && len(doc.Sections) > 0 {
		for _, elem := range doc.Sections[0].Elem {
			text, ok := elem.(present.Text)
			if !ok || text.Pre {
				// skip everything but non-text elements
				continue
			}
			fmt.Fprintf(&md, "Summary:")
			for _, line := range text.Lines {
				fmt.Fprintf(&md, " ")
				printStyled(&md, line)
			}
			fmt.Fprintf(&md, "\n")
			break
		}
	}

	// Authors
	for _, a := range doc.Authors {
		fmt.Fprintf(&md, "\n")
		for _, elem := range a.Elem {
			switch elem := elem.(type) {
			default:
				// Can only happen if this type switch is incomplete, which is a bug.
				log.Fatalf("%s: unexpected author type %T", file, elem)
			case present.Text:
				for _, line := range elem.Lines {
					fmt.Fprintf(&md, "%s\n", markdownEscape(line))
				}
			case present.Link:
				fmt.Fprintf(&md, "%s\n", markdownEscape(elem.Label))
			}
		}
	}

	// Invariant: the output ends in non-blank line now,
	// and after printing any piece of the file below,
	// the output should still end in a non-blank line.
	// If a blank line separator is needed, it should be printed
	// before the block that needs separating, not after.

	if len(doc.TitleNotes) > 0 {
		fmt.Fprintf(&md, "\n")
		for _, line := range doc.TitleNotes {
			fmt.Fprintf(&md, ": %s\n", line)
		}
	}

	if len(doc.Sections) == 1 && strings.HasSuffix(file, ".article") {
		// Blog drops section headers when there is only one section.
		// Don't print a title in this case, to make clear that it's being dropped.
		fmt.Fprintf(&md, "\n##\n")
		printSectionBody(file, 1, &md, doc.Sections[0].Elem)
	} else {
		for _, s := range doc.Sections {
			fmt.Fprintf(&md, "\n")
			fmt.Fprintf(&md, "## %s\n", markdownEscape(s.Title))
			printSectionBody(file, 1, &md, s.Elem)
		}
	}

	if !writeBack {
		os.Stdout.Write(md.Bytes())
		return nil
	}
	return os.WriteFile(file, md.Bytes(), 0666)
}

func printSectionBody(file string, depth int, w *bytes.Buffer, elems []present.Elem) {
	for _, elem := range elems {
		switch elem := elem.(type) {
		default:
			// Can only happen if this type switch is incomplete, which is a bug.
			log.Fatalf("%s: unexpected present element type %T", file, elem)

		case present.Text:
			fmt.Fprintf(w, "\n")
			lines := elem.Lines
			for len(lines) > 0 && lines[0] == "" {
				lines = lines[1:]
			}
			if elem.Pre {
				for line := range strings.SplitSeq(strings.TrimRight(elem.Raw, "\n"), "\n") {
					if line == "" {
						fmt.Fprintf(w, "\n")
					} else {
						fmt.Fprintf(w, "\t%s\n", line)
					}
				}
			} else {
				for _, line := range elem.Lines {
					printStyled(w, line)
					fmt.Fprintf(w, "\n")
				}
			}

		case present.List:
			fmt.Fprintf(w, "\n")
			for _, item := range elem.Bullet {
				fmt.Fprintf(w, "  - ")
				for i, line := range strings.Split(item, "\n") {
					if i > 0 {
						fmt.Fprintf(w, "    ")
					}
					printStyled(w, line)
					fmt.Fprintf(w, "\n")
				}
			}

		case present.Section:
			fmt.Fprintf(w, "\n")
			sep := " "
			if elem.Title == "" {
				sep = ""
			}
			fmt.Fprintf(w, "%s%s%s\n", strings.Repeat("#", depth+2), sep, markdownEscape(elem.Title))
			printSectionBody(file, depth+1, w, elem.Elem)

		case interface{ PresentCmd() string }:
			// If there are multiple present commands in a row, don't print a blank line before the second etc.
			b := w.Bytes()
			sep := "\n"
			if len(b) > 0 {
				i := bytes.LastIndexByte(b[:len(b)-1], '\n')
				if b[i+1] == '.' {
					sep = ""
				}
			}
			fmt.Fprintf(w, "%s%s\n", sep, elem.PresentCmd())
		}
	}
}

func markdownEscape(s string) string {
	var b strings.Builder
	for i, r := range s {
		switch {
		case r == '#' && i == 0,
			r == '*',
			r == '_',
			r == '<' && (i == 0 || s[i-1] != ' ') && i+1 < len(s) && s[i+1] != ' ',
			r == '[' && strings.Contains(s[i:], "]("):
			b.WriteRune('\\')
		}
		b.WriteRune(r)
	}
	return b.String()
}

// Copy of ../../present/style.go adjusted to produce Markdown instead of HTML.

/*
	Fonts are demarcated by an initial and final char bracketing a
	space-delimited word, plus possibly some terminal punctuation.
	The chars are
		_ for italic
		* for bold
		` (back quote) for fixed width.
	Inner appearances of the char become spaces. For instance,
		_this_is_italic_!
	becomes
		<i>this is italic</i>!
*/

func printStyled(w *bytes.Buffer, text string) {
	w.WriteString(font(text))
}

// font returns s with font indicators turned into HTML font tags.
func font(s string) string {
	if !strings.ContainsAny(s, "[`_*") {
		return markdownEscape(s)
	}
	words := split(s)
	var b bytes.Buffer
Word:
	for w, word := range words {
		words[w] = markdownEscape(word) // for all the continue Word
		if len(word) < 2 {
			continue Word
		}
		if link, _ := parseInlineLink(word); link != "" {
			words[w] = link
			continue Word
		}
		const marker = "_*`"
		// Initial punctuation is OK but must be peeled off.
		first := strings.IndexAny(word, marker)
		if first == -1 {
			continue Word
		}
		// Opening marker must be at the beginning of the token or else preceded by punctuation.
		if first != 0 {
			r, _ := utf8.DecodeLastRuneInString(word[:first])
			if !unicode.IsPunct(r) {
				continue Word
			}
		}
		open, word := markdownEscape(word[:first]), word[first:]
		char := word[0] // ASCII is OK.
		close := ""
		switch char {
		default:
			continue Word
		case '_':
			open += "_"
			close = "_"
		case '*':
			open += "**"
			close = "**"
		case '`':
			open += "`"
			close = "`"
		}
		// Closing marker must be at the end of the token or else followed by punctuation.
		last := strings.LastIndex(word, word[:1])
		if last == 0 {
			continue Word
		}
		if last+1 != len(word) {
			r, _ := utf8.DecodeRuneInString(word[last+1:])
			if !unicode.IsPunct(r) {
				continue Word
			}
		}
		head, tail := word[:last+1], word[last+1:]
		b.Reset()
		var wid int
		for i := 1; i < len(head)-1; i += wid {
			var r rune
			r, wid = utf8.DecodeRuneInString(head[i:])
			if r != rune(char) {
				// Ordinary character.
				b.WriteRune(r)
				continue
			}
			if head[i+1] != char {
				// Inner char becomes space.
				b.WriteRune(' ')
				continue
			}
			// Doubled char becomes real char.
			// Not worth worrying about "_x__".
			b.WriteByte(char)
			wid++ // Consumed two chars, both ASCII.
		}
		text := b.String()
		if close == "`" {
			for strings.Contains(text, close) {
				open += "`"
				close += "`"
			}
		} else {
			text = markdownEscape(text)
		}
		words[w] = open + text + close + tail
	}
	return strings.Join(words, "")
}

// split is like strings.Fields but also returns the runs of spaces
// and treats inline links as distinct words.
func split(s string) []string {
	var (
		words = make([]string, 0, 10)
		start = 0
	)

	// appendWord appends the string s[start:end] to the words slice.
	// If the word contains the beginning of a link, the non-link portion
	// of the word and the entire link are appended as separate words,
	// and the start index is advanced to the end of the link.
	appendWord := func(end int) {
		if j := strings.Index(s[start:end], "[["); j > -1 {
			if _, l := parseInlineLink(s[start+j:]); l > 0 {
				// Append portion before link, if any.
				if j > 0 {
					words = append(words, s[start:start+j])
				}
				// Append link itself.
				words = append(words, s[start+j:start+j+l])
				// Advance start index to end of link.
				start = start + j + l
				return
			}
		}
		// No link; just add the word.
		words = append(words, s[start:end])
		start = end
	}

	wasSpace := false
	for i, r := range s {
		isSpace := unicode.IsSpace(r)
		if i > start && isSpace != wasSpace {
			appendWord(i)
		}
		wasSpace = isSpace
	}
	for start < len(s) {
		appendWord(len(s))
	}
	return words
}

// parseInlineLink parses an inline link at the start of s, and returns
// a rendered Markdown link and the total length of the raw inline link.
// If no inline link is present, it returns all zeroes.
func parseInlineLink(s string) (link string, length int) {
	if !strings.HasPrefix(s, "[[") {
		return
	}
	end := strings.Index(s, "]]")
	if end == -1 {
		return
	}
	urlEnd := strings.Index(s, "]")
	rawURL := s[2:urlEnd]
	const badURLChars = `<>"{}|\^[] ` + "`" // per RFC2396 section 2.4.3
	if strings.ContainsAny(rawURL, badURLChars) {
		return
	}
	if urlEnd == end {
		simpleURL := ""
		url, err := url.Parse(rawURL)
		if err == nil {
			// If the URL is http://foo.com, drop the http://
			// In other words, render [[http://golang.org]] as:
			//   <a href="http://golang.org">golang.org</a>
			if after, ok := strings.CutPrefix(rawURL, url.Scheme+"://"); ok {
				simpleURL = after
			} else if after, ok := strings.CutPrefix(rawURL, url.Scheme+":"); ok {
				simpleURL = after
			}
		}
		return renderLink(rawURL, simpleURL), end + 2
	}
	if s[urlEnd:urlEnd+2] != "][" {
		return
	}
	text := s[urlEnd+2 : end]
	return renderLink(rawURL, text), end + 2
}

func renderLink(href, text string) string {
	text = font(text)
	if text == "" {
		text = markdownEscape(href)
	}
	return "[" + text + "](" + href + ")"
}


================================================
FILE: cmd/signature-fuzzer/README.md
================================================
# signature-fuzzer

This directory contains utilities for fuzz testing of Go function signatures, for use in developing/testing a Go compiler.

The basic idea of the fuzzer is that it emits source code for a stand-alone Go program; this generated program is a series of pairs of functions, a "Caller" function and a "Checker" function. The signature of the Checker function is generated randomly (random number of parameters and returns, each with randomly chosen types). The "Caller" func contains invocations of the "Checker" function, each passing randomly chosen values to the params of the "Checker", then the caller verifies that expected values are returned correctly. The "Checker" function in turn has code to verify that the expected values (more details below).

There are three main parts to the fuzzer: a generator package, a driver package, and a runner package.

The "generator" contains the guts of the fuzzer, the bits that actually emit the random code.

The "driver" is a stand-alone program that invokes the generator to create a single test program. It is not terribly useful on its own (since it doesn't actually build or run the generated program), but it is handy for debugging the generator or looking at examples of the emitted code.

The "runner" is a more complete test harness; it repeatedly runs the generator to create a new test program, builds the test program, then runs it (checking for errors along the way). If at any point a build or test fails, the "runner" harness attempts a minimization process to try to narrow down the failure to a single package and/or function.

## What the generated code looks like

Generated Go functions will have an "interesting" set of signatures (mix of
arrays, scalars, structs), intended to pick out corner cases and odd bits in the
Go compiler's code that handles function calls and returns.

The first generated file is genChecker.go, which contains function that look something
like this (simplified):

```
type StructF4S0 struct {
F0 float64
F1 int16
F2 uint16
}

// 0 returns 2 params
func Test4(p0 int8, p1 StructF4S0)  {
  c0 := int8(-1)
  if p0 != c0 {
    NoteFailure(4, "parm", 0)
  }
  c1 := StructF4S0{float64(2), int16(-3), uint16(4)}
  if p1 != c1 {
    NoteFailure(4, "parm", 1)
  }
  return
}
```

Here the test generator has randomly selected 0 return values and 2 params, then randomly generated types for the params.

The generator then emits code on the calling side into the file "genCaller.go", which might look like:

```
func Caller4() {
var p0 int8
p0 = int8(-1)
var p1 StructF4S0
p1 = StructF4S0{float64(2), int16(-3), uint16(4)}
// 0 returns 2 params
Test4(p0, p1)
}
```

The generator then emits some utility functions (ex: NoteFailure) and a main routine that cycles through all of the tests.

## Trying a single run of the generator

To generate a set of source files just to see what they look like, you can build and run the test generator as follows. This creates a new directory "cabiTest" containing generated test files:

```
$ git clone https://golang.org/x/tools
$ cd tools/cmd/signature-fuzzer/fuzz-driver
$ go build .
$ ./fuzz-driver -numpkgs 3 -numfcns 5 -seed 12345 -outdir /tmp/sigfuzzTest -pkgpath foobar
$ cd /tmp/sigfuzzTest
$ find . -type f -print
./genCaller1/genCaller1.go
./genUtils/genUtils.go
./genChecker1/genChecker1.go
./genChecker0/genChecker0.go
./genCaller2/genCaller2.go
./genCaller0/genCaller0.go
./genMain.go
./go.mod
./genChecker2/genChecker2.go
$
```

You can build and run the generated files in the usual way:

```
$ cd /tmp/sigfuzzTest
$ go build .
$ ./foobar
starting main
finished 15 tests
$

```

## Example usage for the test runner

The test runner orchestrates multiple runs of the fuzzer, iteratively emitting code, building it, and testing the resulting binary. To use the runner, build and invoke it with a specific number of iterations; it will select a new random seed on each invocation. The runner will terminate as soon as it finds a failure. Example:

```
$ git clone https://golang.org/x/tools
$ cd tools/cmd/signature-fuzzer/fuzz-runner
$ go build .
$ ./fuzz-runner -numit=3
... begin iteration 0 with current seed 67104558
starting main
finished 1000 tests
... begin iteration 1 with current seed 67104659
starting main
finished 1000 tests
... begin iteration 2 with current seed 67104760
starting main
finished 1000 tests
$
```

If the runner encounters a failure, it will try to perform test-case "minimization", e.g. attempt to isolate the failure

```
$ cd tools/cmd/signature-fuzzer/fuzz-runner
$ go build .
$ ./fuzz-runner -n=10
./fuzz-runner -n=10
... begin iteration 0 with current seed 40661762
Error: fail [reflect] |20|3|1| =Checker3.Test1= return 1
error executing cmd ./fzTest: exit status 1
... starting minimization for failed directory /tmp/fuzzrun1005327337/fuzzTest
package minimization succeeded: found bad pkg 3
function minimization succeeded: found bad fcn 1
$
```

Here the runner has generates a failure, minimized it down to a single function and package, and left the resulting program in the output directory /tmp/fuzzrun1005327337/fuzzTest.

## Limitations, future work

No support yet for variadic functions.

The set of generated types is still a bit thin; it has fairly limited support for interface values, and doesn't include channels.

Todos:

- better interface value coverage

- implement testing of reflect.MakeFunc

- extend to work with generic code of various types

- extend to work in a debugging scenario (e.g. instead of just emitting code,
  emit a script of debugger commands to run the program with expected
  responses from the debugger)

- rework things so that instead of always checking all of a given parameter
  value, we sometimes skip over elements (or just check the length of a slice
  or string as opposed to looking at its value)

- consider adding runtime.GC() calls at some points in the generated code



================================================
FILE: cmd/signature-fuzzer/fuzz-driver/driver.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Stand-alone driver for emitting function-signature test code.  This
// program is mainly just a wrapper around the code that lives in the
// fuzz-generator package; it is useful for generating a specific bad
// code scenario for a given seed, or for doing development on the
// fuzzer, but for doing actual fuzz testing, better to use
// fuzz-runner.

package main

import (
	"flag"
	"fmt"
	"log"
	"math/rand"
	"os"
	"time"

	generator "golang.org/x/tools/cmd/signature-fuzzer/internal/fuzz-generator"
)

// Basic options
var numfcnflag = flag.Int("numfcns", 10, "Number of test func pairs to emit in each package")
var numpkgflag = flag.Int("numpkgs", 1, "Number of test packages to emit")
var seedflag = flag.Int64("seed", -1, "Random seed")
var tagflag = flag.String("tag", "gen", "Prefix name of go files/pkgs to generate")
var outdirflag = flag.String("outdir", "", "Output directory for generated files")
var pkgpathflag = flag.String("pkgpath", "gen", "Base package path for generated files")

// Options used for test case minimization.
var fcnmaskflag = flag.String("fcnmask", "", "Mask containing list of fcn numbers to emit")
var pkmaskflag = flag.String("pkgmask", "", "Mask containing list of pkg numbers to emit")

// Options used to control which features are used in the generated code.
var reflectflag = flag.Bool("reflect", true, "Include testing of reflect.Call.")
var deferflag = flag.Bool("defer", true, "Include testing of defer stmts.")
var recurflag = flag.Bool("recur", true, "Include testing of recursive calls.")
var takeaddrflag = flag.Bool("takeaddr", true, "Include functions that take the address of their parameters and results.")
var methodflag = flag.Bool("method", true, "Include testing of method calls.")
var inlimitflag = flag.Int("inmax", -1, "Max number of input params.")
var outlimitflag = flag.Int("outmax", -1, "Max number of input params.")
var pragmaflag = flag.String("pragma", "", "Tag generated test routines with pragma //go:<value>.")
var maxfailflag = flag.Int("maxfail", 10, "Maximum runtime failures before test self-terminates")
var stackforceflag = flag.Bool("forcestackgrowth", true, "Use hooks to force stack growth.")

// Debugging options
var verbflag = flag.Int("v", 0, "Verbose trace output level")

// Debugging/testing options. These tell the generator to emit "bad" code so as to
// test the logic for detecting errors and/or minimization (in the fuzz runner).
var emitbadflag = flag.Int("emitbad", 0, "[Testing only] force generator to emit 'bad' code.")
var selbadpkgflag = flag.Int("badpkgidx", 0, "[Testing only] select index of bad package (used with -emitbad)")
var selbadfcnflag = flag.Int("badfcnidx", 0, "[Testing only] select index of bad function (used with -emitbad)")

// Misc options
var goimpflag = flag.Bool("goimports", false, "Run 'goimports' on generated code.")
var randctlflag = flag.Int("randctl", generator.RandCtlChecks|generator.RandCtlPanic, "Wraprand control flag")

func verb(vlevel int, s string, a ...any) {
	if *verbflag >= vlevel {
		fmt.Printf(s, a...)
		fmt.Printf("\n")
	}
}

func usage(msg string) {
	if len(msg) > 0 {
		fmt.Fprintf(os.Stderr, "error: %s\n", msg)
	}
	fmt.Fprintf(os.Stderr, "usage: fuzz-driver [flags]\n\n")
	flag.PrintDefaults()
	fmt.Fprintf(os.Stderr, "Example:\n\n")
	fmt.Fprintf(os.Stderr, "  fuzz-driver -numpkgs=23 -numfcns=19 -seed 10101 -outdir gendir\n\n")
	fmt.Fprintf(os.Stderr, "  \tgenerates a Go program with 437 test cases (23 packages, each \n")
	fmt.Fprintf(os.Stderr, "  \twith 19 functions, for a total of 437 funcs total) into a set of\n")
	fmt.Fprintf(os.Stderr, "  \tsub-directories in 'gendir', using random see 10101\n")

	os.Exit(2)
}

func setupTunables() {
	tunables := generator.DefaultTunables()
	if !*reflectflag {
		tunables.DisableReflectionCalls()
	}
	if !*deferflag {
		tunables.DisableDefer()
	}
	if !*recurflag {
		tunables.DisableRecursiveCalls()
	}
	if !*takeaddrflag {
		tunables.DisableTakeAddr()
	}
	if !*methodflag {
		tunables.DisableMethodCalls()
	}
	if *inlimitflag != -1 {
		tunables.LimitInputs(*inlimitflag)
	}
	if *outlimitflag != -1 {
		tunables.LimitOutputs(*outlimitflag)
	}
	generator.SetTunables(tunables)
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("fuzz-driver: ")
	flag.Parse()
	generator.Verbctl = *verbflag
	if *outdirflag == "" {
		usage("select an output directory with -o flag")
	}
	verb(1, "in main verblevel=%d", *verbflag)
	if *seedflag == -1 {
		// user has not selected a specific seed -- pick one.
		now := time.Now()
		*seedflag = now.UnixNano() % 123456789
		verb(0, "selected seed: %d", *seedflag)
	}
	rand.Seed(*seedflag)
	if flag.NArg() != 0 {
		usage("unknown extra arguments")
	}
	verb(1, "tag is %s", *tagflag)

	fcnmask, err := generator.ParseMaskString(*fcnmaskflag, "fcn")
	if err != nil {
		usage(fmt.Sprintf("mangled fcn mask arg: %v", err))
	}
	pkmask, err := generator.ParseMaskString(*pkmaskflag, "pkg")
	if err != nil {
		usage(fmt.Sprintf("mangled pkg mask arg: %v", err))
	}
	verb(2, "pkg mask is %v", pkmask)
	verb(2, "fn mask is %v", fcnmask)

	verb(1, "starting generation")
	setupTunables()
	config := generator.GenConfig{
		PkgPath:          *pkgpathflag,
		Tag:              *tagflag,
		OutDir:           *outdirflag,
		NumTestPackages:  *numpkgflag,
		NumTestFunctions: *numfcnflag,
		Seed:             *seedflag,
		Pragma:           *pragmaflag,
		FcnMask:          fcnmask,
		PkgMask:          pkmask,
		MaxFail:          *maxfailflag,
		ForceStackGrowth: *stackforceflag,
		RandCtl:          *randctlflag,
		RunGoImports:     *goimpflag,
		EmitBad:          *emitbadflag,
		BadPackageIdx:    *selbadpkgflag,
		BadFuncIdx:       *selbadfcnflag,
	}
	errs := generator.Generate(config)
	if errs != 0 {
		log.Fatal("errors during generation")
	}
	verb(1, "... files written to directory %s", *outdirflag)
	verb(1, "leaving main")
}


================================================
FILE: cmd/signature-fuzzer/fuzz-driver/drv_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

// buildDriver builds the fuzz-driver executable, returning its path.
func buildDriver(t *testing.T) string {
	t.Helper()
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
		return ""
	}
	bindir := filepath.Join(t.TempDir(), "bin")
	err := os.Mkdir(bindir, os.ModePerm)
	if err != nil {
		t.Fatal(err)
	}
	binary := filepath.Join(bindir, "driver")
	if runtime.GOOS == "windows" {
		binary += ".exe"
	}
	cmd := exec.Command("go", "build", "-o", binary)
	if err := cmd.Run(); err != nil {
		t.Fatalf("Building fuzz-driver: %v", err)
	}
	return binary
}

func TestEndToEndIntegration(t *testing.T) {
	testenv.NeedsTool(t, "go")
	td := t.TempDir()

	// Build the fuzz-driver binary.
	// Note: if more tests are added to this package, move this to single setup fcn, so
	// that we don't have to redo the build each time.
	binary := buildDriver(t)

	// Kick off a run.
	gendir := filepath.Join(td, "gen")
	args := []string{"-numfcns", "3", "-numpkgs", "1", "-seed", "101", "-outdir", gendir}
	c := exec.Command(binary, args...)
	b, err := c.CombinedOutput()
	if err != nil {
		t.Fatalf("error invoking fuzz-driver: %v\n%s", err, b)
	}

	found := ""
	walker := func(path string, info os.FileInfo, err error) error {
		found = found + ":" + info.Name()
		return nil
	}

	// Make sure it emits something.
	err2 := filepath.Walk(gendir, walker)
	if err2 != nil {
		t.Fatalf("error from filepath.Walk: %v", err2)
	}
	const expected = ":gen:genCaller0:genCaller0.go:genChecker0:genChecker0.go:genMain.go:genUtils:genUtils.go:go.mod"
	if found != expected {
		t.Errorf("walk of generated code: got %s want %s", found, expected)
	}
}


================================================
FILE: cmd/signature-fuzzer/fuzz-runner/rnr_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func canRace() bool {
	_, err := exec.Command("go", "run", "-race", "./testdata/himom.go").CombinedOutput()
	return err == nil
}

// buildRunner builds the fuzz-runner executable, returning its path.
func buildRunner(t *testing.T) string {
	bindir := filepath.Join(t.TempDir(), "bin")
	err := os.Mkdir(bindir, os.ModePerm)
	if err != nil {
		t.Fatal(err)
	}
	binary := filepath.Join(bindir, "runner")
	if runtime.GOOS == "windows" {
		binary += ".exe"
	}
	cmd := exec.Command("go", "build", "-o", binary)
	if err := cmd.Run(); err != nil {
		t.Fatalf("Building fuzz-runner: %v", err)
	}
	return binary
}

// TestRunner builds the binary, then kicks off a collection of sub-tests that invoke it.
func TestRunner(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}
	binaryPath := buildRunner(t)

	// Sub-tests using the binary built above.
	t.Run("Basic", func(t *testing.T) { testBasic(t, binaryPath) })
	t.Run("Race", func(t *testing.T) { testRace(t, binaryPath) })
	t.Run("Minimization1", func(t *testing.T) { testMinimization1(t, binaryPath) })
	t.Run("Minimization2", func(t *testing.T) { testMinimization2(t, binaryPath) })
}

func testBasic(t *testing.T, binaryPath string) {
	t.Parallel()
	args := []string{"-numit=1", "-numfcns=1", "-numpkgs=1", "-seed=103", "-cleancache=0"}
	c := exec.Command(binaryPath, args...)
	b, err := c.CombinedOutput()
	t.Logf("%s\n", b)
	if err != nil {
		t.Fatalf("error invoking fuzz-runner: %v", err)
	}
}

func testRace(t *testing.T, binaryPath string) {
	t.Parallel()
	// For this test to work, the current test platform has to support the
	// race detector. Check to see if that is the case by running a very
	// simple Go program through it.
	if !canRace() {
		t.Skip("current platform does not appear to support the race detector")
	}

	args := []string{"-v=1", "-numit=1", "-race", "-numfcns=3", "-numpkgs=3", "-seed=987", "-cleancache=0"}
	c := exec.Command(binaryPath, args...)
	b, err := c.CombinedOutput()
	t.Logf("%s\n", b)
	if err != nil {
		t.Fatalf("error invoking fuzz-runner: %v", err)
	}
}

func testMinimization1(t *testing.T, binaryPath string) {
	if binaryPath == "" {
		t.Skipf("No runner binary")
	}
	t.Parallel()
	// Fire off the runner passing it -emitbad=1, so that the generated code
	// contains illegal Go code (which will force the build to fail). Verify that
	// it does fail, that the error reflects the nature of the failure, and that
	// we can minimize the error down to a single package.
	args := []string{"-emitbad=1", "-badfcnidx=2", "-badpkgidx=2",
		"-forcetmpclean", "-cleancache=0",
		"-numit=1", "-numfcns=3", "-numpkgs=3", "-seed=909"}
	invocation := fmt.Sprintf("%s %v", binaryPath, args)
	c := exec.Command(binaryPath, args...)
	b, err := c.CombinedOutput()
	t.Logf("%s\n", b)
	if err == nil {
		t.Fatalf("unexpected pass of fuzz-runner (invocation %q): %v", invocation, err)
	}
	result := string(b)
	if !strings.Contains(result, "syntax error") {
		t.Fatalf("-emitbad=1 did not trigger syntax error (invocation %q): output: %s", invocation, result)
	}
	if !strings.Contains(result, "package minimization succeeded: found bad pkg 2") {
		t.Fatalf("failed to minimize package (invocation %q): output: %s", invocation, result)
	}
	if !strings.Contains(result, "function minimization succeeded: found bad fcn 2") {
		t.Fatalf("failed to minimize package (invocation %q): output: %s", invocation, result)
	}
}

func testMinimization2(t *testing.T, binaryPath string) {
	if binaryPath == "" {
		t.Skipf("No runner binary")
	}
	t.Parallel()
	// Fire off the runner passing it -emitbad=2, so that the
	// generated code forces a runtime error. Verify that it does
	// fail, and that the error is reflective.
	args := []string{"-emitbad=2", "-badfcnidx=1", "-badpkgidx=1",
		"-forcetmpclean", "-cleancache=0",
		"-numit=1", "-numfcns=3", "-numpkgs=3", "-seed=55909"}
	invocation := fmt.Sprintf("%s %v", binaryPath, args)
	c := exec.Command(binaryPath, args...)
	b, err := c.CombinedOutput()
	t.Logf("%s\n", b)
	if err == nil {
		t.Fatalf("unexpected pass of fuzz-runner (invocation %q): %v", invocation, err)
	}
	result := string(b)
	if !strings.Contains(result, "Error: fail") || !strings.Contains(result, "Checker1.Test1") {
		t.Fatalf("-emitbad=2 did not trigger runtime error (invocation %q): output: %s", invocation, result)
	}
	if !strings.Contains(result, "package minimization succeeded: found bad pkg 1") {
		t.Fatalf("failed to minimize package (invocation %q): output: %s", invocation, result)
	}
	if !strings.Contains(result, "function minimization succeeded: found bad fcn 1") {
		t.Fatalf("failed to minimize package (invocation %q): output: %s", invocation, result)
	}
}


================================================
FILE: cmd/signature-fuzzer/fuzz-runner/runner.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Program for performing test runs using "fuzz-driver".
// Main loop iteratively runs "fuzz-driver" to create a corpus,
// then builds and runs the code. If a failure in the run is
// detected, then a testcase minimization phase kicks in.

package main

import (
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"time"

	generator "golang.org/x/tools/cmd/signature-fuzzer/internal/fuzz-generator"
)

const pkName = "fzTest"

// Basic options
var verbflag = flag.Int("v", 0, "Verbose trace output level")
var loopitflag = flag.Int("numit", 10, "Number of main loop iterations to run")
var seedflag = flag.Int64("seed", -1, "Random seed")
var execflag = flag.Bool("execdriver", false, "Exec fuzz-driver binary instead of invoking generator directly")
var numpkgsflag = flag.Int("numpkgs", 50, "Number of test packages")
var numfcnsflag = flag.Int("numfcns", 20, "Number of test functions per package.")

// Debugging/testing options. These tell the generator to emit "bad" code so as to
// test the logic for detecting errors and/or minimization.
var emitbadflag = flag.Int("emitbad", -1, "[Testing only] force generator to emit 'bad' code.")
var selbadpkgflag = flag.Int("badpkgidx", 0, "[Testing only] select index of bad package (used with -emitbad)")
var selbadfcnflag = flag.Int("badfcnidx", 0, "[Testing only] select index of bad function (used with -emitbad)")
var forcetmpcleanflag = flag.Bool("forcetmpclean", false, "[Testing only] force cleanup of temp dir")
var cleancacheflag = flag.Bool("cleancache", true, "[Testing only] don't clean the go cache")
var raceflag = flag.Bool("race", false, "[Testing only] build generated code with -race")

func verb(vlevel int, s string, a ...any) {
	if *verbflag >= vlevel {
		fmt.Printf(s, a...)
		fmt.Printf("\n")
	}
}

func warn(s string, a ...any) {
	fmt.Fprintf(os.Stderr, s, a...)
	fmt.Fprintf(os.Stderr, "\n")
}

func fatal(s string, a ...any) {
	fmt.Fprintf(os.Stderr, s, a...)
	fmt.Fprintf(os.Stderr, "\n")
	os.Exit(1)
}

type config struct {
	generator.GenConfig
	tmpdir       string
	gendir       string
	buildOutFile string
	runOutFile   string
	gcflags      string
	nerrors      int
}

func usage(msg string) {
	if len(msg) > 0 {
		fmt.Fprintf(os.Stderr, "error: %s\n", msg)
	}
	fmt.Fprintf(os.Stderr, "usage: fuzz-runner [flags]\n\n")
	flag.PrintDefaults()
	fmt.Fprintf(os.Stderr, "Example:\n\n")
	fmt.Fprintf(os.Stderr, "  fuzz-runner -numit=500 -numpkgs=11 -numfcns=13 -seed=10101\n\n")
	fmt.Fprintf(os.Stderr, "  \tRuns 500 rounds of test case generation\n")
	fmt.Fprintf(os.Stderr, "  \tusing random see 10101, in each round emitting\n")
	fmt.Fprintf(os.Stderr, "  \t11 packages each with 13 function pairs.\n")

	os.Exit(2)
}

// docmd executes the specified command in the dir given and pipes the
// output to stderr. return status is 0 if command passed, 1
// otherwise.
func docmd(cmd []string, dir string) int {
	verb(2, "docmd: %s", strings.Join(cmd, " "))
	c := exec.Command(cmd[0], cmd[1:]...)
	if dir != "" {
		c.Dir = dir
	}
	b, err := c.CombinedOutput()
	st := 0
	if err != nil {
		warn("error executing cmd %s: %v",
			strings.Join(cmd, " "), err)
		st = 1
	}
	os.Stderr.Write(b)
	return st
}

// docmdout forks and execs command 'cmd' in dir 'dir', redirecting
// stderr and stdout from the execution to file 'outfile'.
func docmdout(cmd []string, dir string, outfile string) int {
	of, err := os.OpenFile(outfile, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
	if err != nil {
		fatal("opening outputfile %s: %v", outfile, err)
	}
	c := exec.Command(cmd[0], cmd[1:]...)
	defer of.Close()
	if dir != "" {
		verb(2, "setting cmd.Dir to %s", dir)
		c.Dir = dir
	}
	verb(2, "docmdout: %s > %s", strings.Join(cmd, " "), outfile)
	c.Stdout = of
	c.Stderr = of
	err = c.Run()
	st := 0
	if err != nil {
		warn("error executing cmd %s: %v",
			strings.Join(cmd, " "), err)
		st = 1
	}
	return st
}

// gen is the main hook for kicking off code generation. For
// non-minimization runs, 'singlepk' and 'singlefn' will both be -1
// (indicating that we want all functions and packages to be
// generated).  If 'singlepk' is set to a non-negative value, then
// code generation will be restricted to the single package with that
// index (as a try at minimization), similarly with 'singlefn'
// restricting the codegen to a single specified function.
func (c *config) gen(singlepk int, singlefn int) {

	// clean the output dir
	verb(2, "cleaning outdir %s", c.gendir)
	if err := os.RemoveAll(c.gendir); err != nil {
		fatal("error cleaning gen dir %s: %v", c.gendir, err)
	}

	// emit code into the output dir. Here we either invoke the
	// generator directly, or invoke fuzz-driver if -execflag is
	// set.  If the code generation process itself fails, this is
	// typically a bug in the fuzzer itself, so it gets reported
	// as a fatal error.
	if *execflag {
		args := []string{"fuzz-driver",
			"-numpkgs", strconv.Itoa(c.NumTestPackages),
			"-numfcns", strconv.Itoa(c.NumTestFunctions),
			"-seed", strconv.Itoa(int(c.Seed)),
			"-outdir", c.OutDir,
			"-pkgpath", pkName,
			"-maxfail", strconv.Itoa(c.MaxFail)}
		if singlepk != -1 {
			args = append(args, "-pkgmask", strconv.Itoa(singlepk))
		}
		if singlefn != -1 {
			args = append(args, "-fcnmask", strconv.Itoa(singlefn))
		}
		if *emitbadflag != 0 {
			args = append(args, "-emitbad", strconv.Itoa(*emitbadflag),
				"-badpkgidx", strconv.Itoa(*selbadpkgflag),
				"-badfcnidx", strconv.Itoa(*selbadfcnflag))
		}
		verb(1, "invoking fuzz-driver with args: %v", args)
		st := docmd(args, "")
		if st != 0 {
			fatal("fatal error: generation failed, cmd was: %v", args)
		}
	} else {
		if singlepk != -1 {
			c.PkgMask = map[int]int{singlepk: 1}
		}
		if singlefn != -1 {
			c.FcnMask = map[int]int{singlefn: 1}
		}
		verb(1, "invoking generator.Generate with config: %v", c.GenConfig)
		errs := generator.Generate(c.GenConfig)
		if errs != 0 {
			log.Fatal("errors during generation")
		}
	}
}

// action performs a selected action/command in the generated code dir.
func (c *config) action(cmd []string, outfile string, emitout bool) int {
	st := docmdout(cmd, c.gendir, outfile)
	if emitout {
		content, err := os.ReadFile(outfile)
		if err != nil {
			log.Fatal(err)
		}
		fmt.Fprintf(os.Stderr, "%s", content)
	}
	return st
}

func binaryName() string {
	if runtime.GOOS == "windows" {
		return pkName + ".exe"
	} else {
		return "./" + pkName
	}
}

// build builds a generated corpus of Go code. If 'emitout' is set, then dump out the
// results of the build after it completes (during minimization emitout is set to false,
// since there is no need to see repeated errors).
func (c *config) build(emitout bool) int {
	// Issue a build of the generated code.
	c.buildOutFile = filepath.Join(c.tmpdir, "build.err.txt")
	cmd := []string{"go", "build", "-o", binaryName()}
	if c.gcflags != "" {
		cmd = append(cmd, "-gcflags=all="+c.gcflags)
	}
	if *raceflag {
		cmd = append(cmd, "-race")
	}
	cmd = append(cmd, ".")
	verb(1, "build command is: %v", cmd)
	return c.action(cmd, c.buildOutFile, emitout)
}

// run invokes a binary built from a generated corpus of Go code. If
// 'emitout' is set, then dump out the results of the run after it
// completes.
func (c *config) run(emitout bool) int {
	// Issue a run of the generated code.
	c.runOutFile = filepath.Join(c.tmpdir, "run.err.txt")
	cmd := []string{filepath.Join(c.gendir, binaryName())}
	verb(1, "run command is: %v", cmd)
	return c.action(cmd, c.runOutFile, emitout)
}

type minimizeMode int

const (
	minimizeBuildFailure = iota
	minimizeRuntimeFailure
)

// minimize tries to minimize a failing scenario down to a single
// package and/or function if possible. This is done using an
// iterative search. Here 'minimizeMode' tells us whether we're
// looking for a compile-time error or a runtime error.
func (c *config) minimize(mode minimizeMode) int {

	verb(0, "... starting minimization for failed directory %s", c.gendir)

	foundPkg := -1
	foundFcn := -1

	// Locate bad package. Uses brute-force linear search, could do better...
	for pidx := 0; pidx < c.NumTestPackages; pidx++ {
		verb(1, "minimization: trying package %d", pidx)
		c.gen(pidx, -1)
		st := c.build(false)
		if mode == minimizeBuildFailure {
			if st != 0 {
				// Found.
				foundPkg = pidx
				c.nerrors++
				break
			}
		} else {
			if st != 0 {
				warn("run minimization: unexpected build failed while searching for bad pkg")
				return 1
			}
			st := c.run(false)
			if st != 0 {
				// Found.
				c.nerrors++
				verb(1, "run minimization found bad package: %d", pidx)
				foundPkg = pidx
				break
			}
		}
	}
	if foundPkg == -1 {
		verb(0, "** minimization failed, could not locate bad package")
		return 1
	}
	warn("package minimization succeeded: found bad pkg %d", foundPkg)

	// clean unused packages
	for pidx := 0; pidx < c.NumTestPackages; pidx++ {
		if pidx != foundPkg {
			chp := filepath.Join(c.gendir, fmt.Sprintf("%s%s%d", c.Tag, generator.CheckerName, pidx))
			if err := os.RemoveAll(chp); err != nil {
				fatal("failed to clean pkg subdir %s: %v", chp, err)
			}
			clp := filepath.Join(c.gendir, fmt.Sprintf("%s%s%d", c.Tag, generator.CallerName, pidx))
			if err := os.RemoveAll(clp); err != nil {
				fatal("failed to clean pkg subdir %s: %v", clp, err)
			}
		}
	}

	// Locate bad function. Again, brute force.
	for fidx := 0; fidx < c.NumTestFunctions; fidx++ {
		c.gen(foundPkg, fidx)
		st := c.build(false)
		if mode == minimizeBuildFailure {
			if st != 0 {
				// Found.
				verb(1, "build minimization found bad function: %d", fidx)
				foundFcn = fidx
				break
			}
		} else {
			if st != 0 {
				warn("run minimization: unexpected build failed while searching for bad fcn")
				return 1
			}
			st := c.run(false)
			if st != 0 {
				// Found.
				verb(1, "run minimization found bad function: %d", fidx)
				foundFcn = fidx
				break
			}
		}
		// not the function we want ... continue the hunt
	}
	if foundFcn == -1 {
		verb(0, "** function minimization failed, could not locate bad function")
		return 1
	}
	warn("function minimization succeeded: found bad fcn %d", foundFcn)

	return 0
}

// cleanTemp removes the temp dir we've been working with.
func (c *config) cleanTemp() {
	if !*forcetmpcleanflag {
		if c.nerrors != 0 {
			verb(1, "preserving temp dir %s", c.tmpdir)
			return
		}
	}
	verb(1, "cleaning temp dir %s", c.tmpdir)
	os.RemoveAll(c.tmpdir)
}

// perform is the top level driver routine for the program, containing the
// main loop. Each iteration of the loop performs a generate/build/run
// sequence, and then updates the seed afterwards if no failure is found.
// If a failure is detected, we try to minimize it and then return without
// attempting any additional tests.
func (c *config) perform() int {
	defer c.cleanTemp()

	// Main loop
	for iter := 0; iter < *loopitflag; iter++ {
		if iter != 0 && iter%50 == 0 {
			// Note: cleaning the Go cache periodically is
			// pretty much a requirement if you want to do
			// things like overnight runs of the fuzzer,
			// but it is also a very unfriendly thing do
			// to if we're executing as part of a unit
			// test run (in which case there may be other
			// tests running in parallel with this
			// one). Check the "cleancache" flag before
			// doing this.
			if *cleancacheflag {
				docmd([]string{"go", "clean", "-cache"}, "")
			}
		}
		verb(0, "... begin iteration %d with current seed %d", iter, c.Seed)
		c.gen(-1, -1)
		st := c.build(true)
		if st != 0 {
			c.minimize(minimizeBuildFailure)
			return 1
		}
		st = c.run(true)
		if st != 0 {
			c.minimize(minimizeRuntimeFailure)
			return 1
		}
		// update seed so that we get different code on the next iter.
		c.Seed += 101
	}
	return 0
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("fuzz-runner: ")
	flag.Parse()
	if flag.NArg() != 0 {
		usage("unknown extra arguments")
	}
	verb(1, "in main, verblevel=%d", *verbflag)

	tmpdir, err := os.MkdirTemp("", "fuzzrun")
	if err != nil {
		fatal("creation of tempdir failed: %v", err)
	}
	gendir := filepath.Join(tmpdir, "fuzzTest")

	// select starting seed
	if *seedflag == -1 {
		now := time.Now()
		*seedflag = now.UnixNano() % 123456789
	}

	// set up params for this run
	c := &config{
		GenConfig: generator.GenConfig{
			NumTestPackages:  *numpkgsflag, // 100
			NumTestFunctions: *numfcnsflag, // 20
			Seed:             *seedflag,
			OutDir:           gendir,
			Pragma:           "-maxfail=9999",
			PkgPath:          pkName,
			EmitBad:          *emitbadflag,
			BadPackageIdx:    *selbadpkgflag,
			BadFuncIdx:       *selbadfcnflag,
		},
		tmpdir: tmpdir,
		gendir: gendir,
	}

	// kick off the main loop.
	st := c.perform()

	// done
	verb(1, "leaving main, num errors=%d", c.nerrors)
	os.Exit(st)
}


================================================
FILE: cmd/signature-fuzzer/fuzz-runner/testdata/himom.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

func main() {
	println("hi mom!")
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/arrayparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
)

// arrayparm describes a parameter of array type; it implements the
// "parm" interface.
type arrayparm struct {
	aname     string
	qname     string
	nelements uint8
	eltype    parm
	slice     bool
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p arrayparm) IsControl() bool {
	return false
}

func (p arrayparm) TypeName() string {
	return p.aname
}

func (p arrayparm) QualName() string {
	return p.qname
}

func (p arrayparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	n := p.aname
	if caller {
		n = p.qname
	}
	b.WriteString(fmt.Sprintf("%s %s%s", prefix, n, suffix))
}

func (p arrayparm) String() string {
	return fmt.Sprintf("%s %d-element array of %s", p.aname, p.nelements, p.eltype.String())
}

func (p arrayparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	var buf bytes.Buffer

	verb(5, "arrayparm.GenValue(%d)", value)

	n := p.aname
	if caller {
		n = p.qname
	}
	buf.WriteString(fmt.Sprintf("%s{", n))
	for i := 0; i < int(p.nelements); i++ {
		var valstr string
		valstr, value = s.GenValue(f, p.eltype, value, caller)
		writeCom(&buf, i)
		buf.WriteString(valstr)
	}
	buf.WriteString("}")
	return buf.String(), value
}

func (p arrayparm) GenElemRef(elidx int, path string) (string, parm) {
	ene := p.eltype.NumElements()
	verb(4, "begin GenElemRef(%d,%s) on %s ene %d", elidx, path, p.String(), ene)

	// For empty arrays, convention is to return empty string
	if ene == 0 {
		return "", &p
	}

	// Find slot within array of element of interest
	slot := elidx / ene

	// If this is the element we're interested in, return it
	if ene == 1 {
		verb(4, "hit scalar element")
		epath := fmt.Sprintf("%s[%d]", path, slot)
		if path == "_" || p.IsBlank() {
			epath = "_"
		}
		return epath, p.eltype
	}

	verb(4, "recur slot=%d GenElemRef(%d,...)", slot, elidx-(slot*ene))

	// Otherwise our victim is somewhere inside the slot
	ppath := fmt.Sprintf("%s[%d]", path, slot)
	if p.IsBlank() {
		ppath = "_"
	}
	return p.eltype.GenElemRef(elidx-(slot*ene), ppath)
}

func (p arrayparm) NumElements() int {
	return p.eltype.NumElements() * int(p.nelements)
}

func (p arrayparm) HasPointer() bool {
	return p.eltype.HasPointer() || p.slice
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/gen_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func mkGenState() *genstate {

	return &genstate{
		GenConfig: GenConfig{
			Tag:              "gen",
			OutDir:           "/tmp",
			NumTestPackages:  1,
			NumTestFunctions: 10,
		},
		ipref:       "foo/",
		derefFuncs:  make(map[string]string),
		assignFuncs: make(map[string]string),
		allocFuncs:  make(map[string]string),
		globVars:    make(map[string]string),
	}
}

func TestBasic(t *testing.T) {
	checkTunables(tunables)
	s := mkGenState()
	for i := range 1000 {
		s.wr = NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		fp := s.GenFunc(i, i)
		var buf bytes.Buffer
		var b *bytes.Buffer = &buf
		wr := NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		s.wr = wr
		s.emitCaller(fp, b, i)
		s.wr = NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		s.emitChecker(fp, b, i, true)
		wr.Check(s.wr)
	}
	if s.errs != 0 {
		t.Errorf("%d errors during Generate", s.errs)
	}
}

func TestMoreComplicated(t *testing.T) {
	saveit := tunables
	defer func() { tunables = saveit }()

	checkTunables(tunables)
	s := mkGenState()
	for i := range 10000 {
		s.wr = NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		fp := s.GenFunc(i, i)
		var buf bytes.Buffer
		var b *bytes.Buffer = &buf
		wr := NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		s.wr = wr
		s.emitCaller(fp, b, i)
		verb(1, "finished iter %d caller", i)
		s.wr = NewWrapRand(int64(i), RandCtlChecks|RandCtlPanic)
		s.emitChecker(fp, b, i, true)
		verb(1, "finished iter %d checker", i)
		wr.Check(s.wr)
		if s.errs != 0 {
			t.Errorf("%d errors during Generate iter %d", s.errs, i)
		}
	}
}

func TestIsBuildable(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}

	td := t.TempDir()
	verb(1, "generating into temp dir %s", td)
	checkTunables(tunables)
	pack := filepath.Base(td)
	s := GenConfig{
		Tag:              "x",
		OutDir:           td,
		PkgPath:          pack,
		NumTestFunctions: 10,
		NumTestPackages:  10,
		MaxFail:          10,
		RandCtl:          RandCtlChecks | RandCtlPanic,
	}
	errs := Generate(s)
	if errs != 0 {
		t.Errorf("%d errors during Generate", errs)
	}

	verb(1, "building %s\n", td)

	cmd := exec.Command("go", "run", ".")
	cmd.Dir = td
	coutput, cerr := cmd.CombinedOutput()
	if cerr != nil {
		t.Errorf("go build command failed: %s\n", string(coutput))
	}
	verb(1, "output is: %s\n", string(coutput))
}

// TestExhaustive does a series of code generation runs, starting with
// (relatively) simple code and then getting progressively more
// complex (more params, deeper structs, turning on additional
// features such as address-taken vars and reflect testing). The
// intent here is mainly to insure that the tester still works if you
// turn things on and off, e.g. that each feature is separately
// controllable and not linked to other things.
func TestExhaustive(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}

	if testing.Short() {
		t.Skip("skipping test in short mode.")
	}

	td := t.TempDir()
	verb(1, "generating into temp dir %s", td)

	scenarios := []struct {
		name     string
		adjuster func()
	}{
		{
			"minimal",
			func() {
				tunables.nParmRange = 3
				tunables.nReturnRange = 3
				tunables.structDepth = 1
				tunables.recurPerc = 0
				tunables.methodPerc = 0
				tunables.doReflectCall = false
				tunables.doDefer = false
				tunables.takeAddress = false
				tunables.doFuncCallValues = false
				tunables.doSkipCompare = false
				checkTunables(tunables)
			},
		},
		{
			"moreparms",
			func() {
				tunables.nParmRange = 15
				tunables.nReturnRange = 7
				tunables.structDepth = 3
				checkTunables(tunables)
			},
		},
		{
			"addrecur",
			func() {
				tunables.recurPerc = 20
				checkTunables(tunables)
			},
		},
		{
			"addmethod",
			func() {
				tunables.methodPerc = 25
				tunables.pointerMethodCallPerc = 30
				checkTunables(tunables)
			},
		},
		{
			"addtakeaddr",
			func() {
				tunables.takeAddress = true
				tunables.takenFraction = 20
				checkTunables(tunables)
			},
		},
		{
			"addreflect",
			func() {
				tunables.doReflectCall = true
				checkTunables(tunables)
			},
		},
		{
			"adddefer",
			func() {
				tunables.doDefer = true
				checkTunables(tunables)
			},
		},
		{
			"addfuncval",
			func() {
				tunables.doFuncCallValues = true
				checkTunables(tunables)
			},
		},
		{
			"addfuncval",
			func() {
				tunables.doSkipCompare = true
				checkTunables(tunables)
			},
		},
	}

	// Loop over scenarios and make sure each one works properly.
	for i, s := range scenarios {
		t.Logf("running %s\n", s.name)
		s.adjuster()
		os.RemoveAll(td)
		pack := filepath.Base(td)
		c := GenConfig{
			Tag:              "x",
			OutDir:           td,
			PkgPath:          pack,
			NumTestFunctions: 10,
			NumTestPackages:  10,
			Seed:             int64(i + 9),
			MaxFail:          10,
			RandCtl:          RandCtlChecks | RandCtlPanic,
		}
		errs := Generate(c)
		if errs != 0 {
			t.Errorf("%d errors during scenarios %q Generate", errs, s.name)
		}
		cmd := exec.Command("go", "run", ".")
		cmd.Dir = td
		coutput, cerr := cmd.CombinedOutput()
		if cerr != nil {
			t.Fatalf("run failed for scenario %q:  %s\n", s.name, string(coutput))
		}
		verb(1, "output is: %s\n", string(coutput))
	}
}

func TestEmitBadBuildFailure(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}

	td := t.TempDir()
	verb(1, "generating into temp dir %s", td)

	checkTunables(tunables)
	pack := filepath.Base(td)
	s := GenConfig{
		Tag:              "x",
		OutDir:           td,
		PkgPath:          pack,
		NumTestFunctions: 10,
		NumTestPackages:  10,
		MaxFail:          10,
		RandCtl:          RandCtlChecks | RandCtlPanic,
		EmitBad:          1,
	}
	errs := Generate(s)
	if errs != 0 {
		t.Errorf("%d errors during Generate", errs)
	}

	cmd := exec.Command("go", "build", ".")
	cmd.Dir = td
	coutput, cerr := cmd.CombinedOutput()
	if cerr == nil {
		t.Errorf("go build command passed, expected failure. output: %s\n", string(coutput))
	}
}

func TestEmitBadRunFailure(t *testing.T) {
	testenv.NeedsTool(t, "go")
	if runtime.GOOS == "android" {
		t.Skipf("the dependencies are not available on android")
	}

	td := t.TempDir()
	verb(1, "generating into temp dir %s", td)

	checkTunables(tunables)
	pack := filepath.Base(td)
	s := GenConfig{
		Tag:              "x",
		OutDir:           td,
		PkgPath:          pack,
		NumTestFunctions: 10,
		NumTestPackages:  10,
		MaxFail:          10,
		RandCtl:          RandCtlChecks | RandCtlPanic,
		EmitBad:          2,
	}
	errs := Generate(s)
	if errs != 0 {
		t.Errorf("%d errors during Generate", errs)
	}

	// build
	cmd := exec.Command("go", "build", ".")
	cmd.Dir = td
	coutput, cerr := cmd.CombinedOutput()
	if cerr != nil {
		t.Fatalf("build failed: %s\n", string(coutput))
	}

	// run
	cmd = exec.Command("./" + pack)
	cmd.Dir = td
	coutput, cerr = cmd.CombinedOutput()
	if cerr == nil {
		t.Fatalf("run passed, expected failure -- run output: %s", string(coutput))
	}
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/generator.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This package generates source code for a stand-alone Go program
// useful for function signature fuzzing. The generated program is a
// series of function pairs, a "Caller" function and a "Checker"
// function. The signature of the Checker function is generated
// randomly (random number of parameters and returns, each with
// randomly chosen types). The "Caller" func contains invocations of
// the "Checker" function, each passing randomly chosen values to the
// params of the "Checker", then the caller verifies that expected
// values are returned correctly.  The "Checker" function in turn has
// code to verify that the expected values arrive correctly, and so
// on.
//
// The main exported items of interest for this package are:
//
// - the Generate function, which takes a GenConfig object and emits
//   code according to the config's specification
//
// - the GenConfig struct, which is basically a large collection of
//   knobs/switches to control the mechanics of how/where code is
//   generated
//
// - the TunableParams struct, which controls the nature of the
//   generated code (for example, the maximum number of function
//   parameters, etc), and the SetTunables func which tells the
//   package what tunable parameters to use.

// Notes for posterity:
// - many parts of this package would have been better off being written
//   using text/template instead of generating code directly; perhaps
//   at some point it could be converted over (big job).
// - for the various 'fractions' fields in the TunableParams struct,
//   it would be good to have a named type of some sort, with methods
//   for managing things like checking to make sure values sum to 100.

package generator

import (
	"bytes"
	"crypto/sha1"
	"errors"
	"fmt"
	"html/template"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strconv"
	"strings"
)

// GenConfig contains configuration parameters relating to the
// mechanics of the code generation, e.g. how many packages/functions
// to emit, path to a directory into which we place the generated
// code, prefixes/packagenames for the generate code, and so on.
type GenConfig struct {
	// Tag is a string prefix prepended to functions within
	// the generated code.
	Tag string

	// Output directory in to which we'll emit generated code.
	// This will be created if it does not exist.
	OutDir string

	// Packagepath prefix given to the generated code.
	PkgPath string

	// Number of test packages created within the generated corpus.
	// Each test package is essentially an independent collection
	// generated code; the point of having multiple packages is to
	// be able to get faster builds (more parallelism), and to avoid
	// the compile time issues that crop up with 'giant' packages.
	NumTestPackages int

	// Number of test function pairs within each generated test package.
	// Each pair consists of a "caller" function and  "callee" function.
	NumTestFunctions int

	// Seed for random number generator.
	Seed int64

	// Pragma is a "// go:..." compiler directive to apply to the
	// callee function as part of a generated function pair.
	Pragma string

	// Function and package mask used for minimization purposes.
	// If a given mask is non-nil, then the generator will only
	// emit code for a given func or package if its index is
	// present in the mask map.
	FcnMask map[int]int
	PkgMask map[int]int

	// Maximum number of failures to encounter before bailing out.
	MaxFail int

	// forcestackgrowth if set tells the generator to insert
	// calls to runtime.gcTestMoveStackOnNextCall at various points
	// in the generated code.
	ForceStackGrowth bool

	// Random number generator control flag (debugging)
	RandCtl int

	// Tells the generator to run "goimports" on the emitted code.
	RunGoImports bool

	// Debugging/testing hook. If set to 1, emit code that will cause the
	// build to fail; if set to 2, emit code that will cause a test to fail.
	EmitBad int

	// If EmitBad above is set, then these can be used to select the ID of
	// a specific bad func/package.
	BadPackageIdx int
	BadFuncIdx    int
}

const CallerName = "Caller"
const CheckerName = "Checker"

// TunableParams contains configuration parameters that control the
// flavor of code generated for a given test function. This includes
// things like the number of params/returns, the percentages of types
// (int, struct, etc) of the params/returns, and so on.
type TunableParams struct {
	// between 0 and N params
	nParmRange uint8

	// between 0 and N returns
	nReturnRange uint8

	// structs have between 0 and N members
	nStructFields uint8

	// arrays/slices have between 0 and N elements
	nArrayElements uint8

	// fraction of slices vs arrays. This is a value between 0 and 100 (0 meaning
	// no slices [only arrays] and 100 meaning all slices, no arrays).
	sliceFraction uint8

	// Controls how often "int" vars wind up as 8/16/32/64, should
	// add up to 100. Ex: 100 0 0 0 means all ints are 8 bit, 25
	// 25 25 25 means equal likelihood of all types.
	intBitRanges [4]uint8

	// Similar to the above but for 32/64 float types
	floatBitRanges [2]uint8

	// Similar to the above but for unsigned, signed ints.
	unsignedRanges [2]uint8

	// Percentage of params, struct fields that should be "_". Ranges
	// from 0 to 100.
	blankPerc uint8

	// How deeply structs are allowed to be nested (ranges from 0 to N).
	structDepth uint8

	// Fraction of param and return types assigned to each of:
	// struct/array/map/pointer/int/float/complex/byte/string at the
	// top level. If nesting precludes using a struct, other types
	// are chosen from instead according to same proportions. The sum
	// of typeFractions values should add up to 100.
	typeFractions [9]uint8

	// Percentage of the time we'll emit recursive calls, from 0 to 100.
	recurPerc uint8

	// Percentage of time that we turn the test function into a method,
	// and if it is a method, fraction of time that we use a pointer
	// method call vs value method call. Each range from 0 to 100.
	methodPerc            uint8
	pointerMethodCallPerc uint8

	// If true, test reflect.Call path as well.
	doReflectCall bool

	// If true, then randomly take addresses of params/returns.
	takeAddress bool

	// Fraction of the time that any params/returns are address taken.
	// Ranges from 0 to 100.
	takenFraction uint8

	// For a given address-taken param or return, controls the
	// manner in which the indirect read or write takes
	// place. This is a set of percentages for
	// not/simple/passed/heap, where "not" means not address
	// taken, "simple" means a simple read or write, "passed"
	// means that the address is passed to a well-behaved
	// function, and "heap" means that the address is assigned to
	// a global. Values in addrFractions should add up to 100.
	addrFractions [4]uint8

	// If true, then perform testing of go/defer statements.
	doDefer bool

	// fraction of test functions for which we emit a defer. Ranges from 0 to 100.
	deferFraction uint8

	// If true, randomly pick between emitting a value by literal
	// (e.g. "int(1)" vs emitting a call to a function that
	// will produce the same value (e.g. "myHelperEmitsInt1()").
	doFuncCallValues bool

	// Fraction of the time that we emit a function call to create
	// a param value vs emitting a literal. Ranges from 0 to 100.
	funcCallValFraction uint8

	// If true, randomly decide to not check selected components of
	// a composite value (e.g. for a struct, check field F1 but not F2).
	// The intent is to generate partially live values.
	doSkipCompare bool

	// Fraction of the time that we decided to skip sub-components of
	// composite values. Ranges from 0 to 100.
	skipCompareFraction uint8
}

// SetTunables accepts a TunableParams object, checks to make sure
// that the settings in it are sane/logical, and applies the
// parameters for any subsequent calls to the Generate function. This
// function will issue a fatal error if any of the tunable params are
// incorrect/insane (for example, a 'percentage' value outside the
// range of 0-100).
func SetTunables(t TunableParams) {
	checkTunables(t)
	tunables = t
}

var defaultTypeFractions = [9]uint8{
	10, // struct
	10, // array
	10, // map
	15, // pointer
	20, // numeric
	15, // float
	5,  // complex
	5,  // byte
	10, // string
}

const (
	// Param not address taken.
	StructTfIdx = iota
	ArrayTfIdx
	MapTfIdx
	PointerTfIdx
	NumericTfIdx
	FloatTfIdx
	ComplexTfIdx
	ByteTfIdx
	StringTfIdx
)

var tunables = TunableParams{
	nParmRange:            15,
	nReturnRange:          7,
	nStructFields:         7,
	nArrayElements:        5,
	sliceFraction:         50,
	intBitRanges:          [4]uint8{30, 20, 20, 30},
	floatBitRanges:        [2]uint8{50, 50},
	unsignedRanges:        [2]uint8{50, 50},
	blankPerc:             15,
	structDepth:           3,
	typeFractions:         defaultTypeFractions,
	recurPerc:             20,
	methodPerc:            10,
	pointerMethodCallPerc: 50,
	doReflectCall:         true,
	doDefer:               true,
	takeAddress:           true,
	doFuncCallValues:      true,
	takenFraction:         20,
	deferFraction:         30,
	funcCallValFraction:   5,
	doSkipCompare:         true,
	skipCompareFraction:   10,
	addrFractions:         [4]uint8{50, 25, 15, 10},
}

func DefaultTunables() TunableParams {
	return tunables
}

func checkTunables(t TunableParams) {
	var s int = 0

	for _, v := range t.intBitRanges {
		s += int(v)
	}
	if s != 100 {
		log.Fatal(errors.New("intBitRanges tunable does not sum to 100"))
	}

	s = 0
	for _, v := range t.unsignedRanges {
		s += int(v)
	}
	if s != 100 {
		log.Fatal(errors.New("unsignedRanges tunable does not sum to 100"))
	}

	if t.blankPerc > 100 {
		log.Fatal(errors.New("blankPerc bad value, over 100"))
	}
	if t.recurPerc > 100 {
		log.Fatal(errors.New("recurPerc bad value, over 100"))
	}
	if t.methodPerc > 100 {
		log.Fatal(errors.New("methodPerc bad value, over 100"))
	}
	if t.pointerMethodCallPerc > 100 {
		log.Fatal(errors.New("pointerMethodCallPerc bad value, over 100"))
	}

	s = 0
	for _, v := range t.floatBitRanges {
		s += int(v)
	}
	if s != 100 {
		log.Fatal(errors.New("floatBitRanges tunable does not sum to 100"))
	}

	s = 0
	for _, v := range t.typeFractions {
		s += int(v)
	}
	if s != 100 {
		panic(errors.New("typeFractions tunable does not sum to 100"))
	}

	s = 0
	for _, v := range t.addrFractions {
		s += int(v)
	}
	if s != 100 {
		log.Fatal(errors.New("addrFractions tunable does not sum to 100"))
	}
	if t.takenFraction > 100 {
		log.Fatal(errors.New("takenFraction not between 0 and 100"))
	}
	if t.deferFraction > 100 {
		log.Fatal(errors.New("deferFraction not between 0 and 100"))
	}
	if t.sliceFraction > 100 {
		log.Fatal(errors.New("sliceFraction not between 0 and 100"))
	}
	if t.skipCompareFraction > 100 {
		log.Fatal(errors.New("skipCompareFraction not between 0 and 100"))
	}
}

func (t *TunableParams) DisableReflectionCalls() {
	t.doReflectCall = false
}

func (t *TunableParams) DisableRecursiveCalls() {
	t.recurPerc = 0
}

func (t *TunableParams) DisableMethodCalls() {
	t.methodPerc = 0
}

func (t *TunableParams) DisableTakeAddr() {
	t.takeAddress = false
}

func (t *TunableParams) DisableDefer() {
	t.doDefer = false
}

func (t *TunableParams) LimitInputs(n int) error {
	if n > 100 {
		return fmt.Errorf("value %d passed to LimitInputs is too large *(max 100)", n)
	}
	if n < 0 {
		return fmt.Errorf("value %d passed to LimitInputs is invalid", n)
	}
	t.nParmRange = uint8(n)
	return nil
}

func (t *TunableParams) LimitOutputs(n int) error {
	if n > 100 {
		return fmt.Errorf("value %d passed to LimitOutputs is too large *(max 100)", n)
	}
	if n < 0 {
		return fmt.Errorf("value %d passed to LimitOutputs is invalid", n)
	}
	t.nReturnRange = uint8(n)
	return nil
}

// ParseMaskString parses a string of the form K,J,...,M-N,Q-R,...,Z
// e.g. comma-separated integers or ranges of integers, returning the
// result in a form suitable for FcnMask or PkgMask fields in a
// Config. Here "tag" holds the mask flavor (fcn or pkg) and "arg" is
// the string argument to be parsed.
func ParseMaskString(arg string, tag string) (map[int]int, error) {
	if arg == "" {
		return nil, nil
	}
	verb(1, "%s mask is %s", tag, arg)
	m := make(map[int]int)
	for s := range strings.SplitSeq(arg, ":") {
		if strings.Contains(s, "-") {
			rng := strings.Split(s, "-")
			if len(rng) != 2 {
				return nil, fmt.Errorf("malformed range %s in %s mask arg", s, tag)
			}
			i, err := strconv.Atoi(rng[0])
			if err != nil {
				return nil, fmt.Errorf("malformed range value %s in %s mask arg", rng[0], tag)
			}
			j, err2 := strconv.Atoi(rng[1])
			if err2 != nil {
				return nil, fmt.Errorf("malformed range value %s in %s mask arg", rng[1], tag)
			}
			for k := i; k < j; k++ {
				m[k] = 1
			}
		} else {
			i, err := strconv.Atoi(s)
			if err != nil {
				return nil, fmt.Errorf("malformed value %s in %s mask arg", s, tag)
			}
			m[i] = 1
		}
	}
	return m, nil
}

func writeCom(b *bytes.Buffer, i int) {
	if i != 0 {
		b.WriteString(", ")
	}
}

var Verbctl int = 0

func verb(vlevel int, s string, a ...any) {
	if Verbctl >= vlevel {
		fmt.Printf(s, a...)
		fmt.Printf("\n")
	}
}

type funcdef struct {
	idx         int
	structdefs  []structparm
	arraydefs   []arrayparm
	typedefs    []typedefparm
	mapdefs     []mapparm
	mapkeytypes []parm
	mapkeytmps  []string
	mapkeyts    string
	receiver    parm
	params      []parm
	returns     []parm
	values      []int
	dodefc      uint8
	dodefp      []uint8
	rstack      int
	recur       bool
	isMethod    bool
}

type genstate struct {
	GenConfig
	ipref string
	//tag            string
	//numtpk         int
	pkidx int
	errs  int
	//pragma         string
	//sforce         bool
	//randctl        int
	tunables       TunableParams
	tstack         []TunableParams
	derefFuncs     map[string]string
	newDerefFuncs  []funcdesc
	assignFuncs    map[string]string
	newAssignFuncs []funcdesc
	allocFuncs     map[string]string
	newAllocFuncs  []funcdesc
	genvalFuncs    map[string]string
	newGenvalFuncs []funcdesc
	globVars       map[string]string
	newGlobVars    []funcdesc
	wr             *wraprand
}

func (s *genstate) intFlavor() string {
	which := uint8(s.wr.Intn(100))
	if which < s.tunables.unsignedRanges[0] {
		return "uint"
	}
	return "int"
}

func (s *genstate) intBits() uint32 {
	which := uint8(s.wr.Intn(100))
	var t uint8 = 0
	var bits uint32 = 8
	for _, v := range s.tunables.intBitRanges {
		t += v
		if which < t {
			return bits
		}
		bits *= 2
	}
	return uint32(s.tunables.intBitRanges[3])
}

func (s *genstate) floatBits() uint32 {
	which := uint8(s.wr.Intn(100))
	if which < s.tunables.floatBitRanges[0] {
		return uint32(32)
	}
	return uint32(64)
}

func (s *genstate) genAddrTaken() addrTakenHow {
	which := uint8(s.wr.Intn(100))
	res := notAddrTaken
	var t uint8 = 0
	for _, v := range s.tunables.addrFractions {
		t += v
		if which < t {
			return res
		}
		res++
	}
	return notAddrTaken
}

func (s *genstate) pushTunables() {
	s.tstack = append(s.tstack, s.tunables)
}

func (s *genstate) popTunables() {
	if len(s.tstack) == 0 {
		panic("untables stack underflow")
	}
	s.tunables = s.tstack[0]
	s.tstack = s.tstack[1:]
}

// redistributeFraction accepts a value 'toIncorporate' and updates
// 'typeFraction' to add in the values from 'toIncorporate' equally to
// all slots not in 'avoid'. This is done by successively walking
// through 'typeFraction' adding 1 to each non-avoid slot, then
// repeating until we've added a total of 'toIncorporate' elements.
// See precludeSelectedTypes below for more info.
func (s *genstate) redistributeFraction(toIncorporate uint8, avoid []int) {
	inavoid := func(j int) bool {
		return slices.Contains(avoid, j)
	}

	doredis := func() {
		for {
			for i := range s.tunables.typeFractions {
				if inavoid(i) {
					continue
				}
				s.tunables.typeFractions[i]++
				toIncorporate--
				if toIncorporate == 0 {
					return
				}
			}
		}
	}
	doredis()
	checkTunables(s.tunables)
}

// precludeSelectedTypes accepts a set of values (t, t2, ...)
// corresponding to slots in 'typeFractions', sums up the values from
// the slots, zeroes out the slots, and finally takes the values and
// redistributes them equally to the other slots.  For example,
// suppose 'typeFractions' starts as [10, 10, 10, 15, 20, 15, 5, 5, 10],
// then we decide we want to eliminate or 'knock out' map types and
// pointer types (slots 2 and 3 in the array above) going forward.  To
// restore the invariant that values in 'typeFractions' sum to 100, we
// take the values from slots 2 and 3 (a total of 25) and evenly
// distribute those values to the other slots in the array.
func (s *genstate) precludeSelectedTypes(t int, t2 ...int) {
	avoid := []int{t}
	avoid = append(avoid, t2...)
	f := uint8(0)
	for _, idx := range avoid {
		f += s.tunables.typeFractions[idx]
		s.tunables.typeFractions[idx] = 0
	}
	s.redistributeFraction(f, avoid)
}

func (s *genstate) GenMapKeyType(f *funcdef, depth int, pidx int) parm {
	s.pushTunables()
	defer s.popTunables()
	// maps we can't allow at all; pointers might be possible but
	//  would be too much work to arrange. Avoid slices as well.
	s.tunables.sliceFraction = 0
	s.precludeSelectedTypes(MapTfIdx, PointerTfIdx)
	return s.GenParm(f, depth+1, false, pidx)
}

func (s *genstate) GenParm(f *funcdef, depth int, mkctl bool, pidx int) parm {

	// Enforcement for struct/array/map/pointer array nesting depth.
	toodeep := depth >= int(s.tunables.structDepth)
	if toodeep {
		s.pushTunables()
		defer s.popTunables()
		s.precludeSelectedTypes(StructTfIdx, ArrayTfIdx, MapTfIdx, PointerTfIdx)
	}

	// Convert tf into a cumulative sum
	tf := s.tunables.typeFractions
	sum := uint8(0)
	for i := range len(tf) {
		sum += tf[i]
		tf[i] = sum
	}

	isblank := uint8(s.wr.Intn(100)) < s.tunables.blankPerc
	addrTaken := notAddrTaken
	if depth == 0 && tunables.takeAddress && !isblank {
		addrTaken = s.genAddrTaken()
	}
	isGenValFunc := tunables.doFuncCallValues &&
		uint8(s.wr.Intn(100)) < s.tunables.funcCallValFraction

	// Make adjusted selection (pick a bucket within tf)
	which := uint8(s.wr.Intn(100))
	verb(3, "which=%d", which)
	var retval parm
	switch {
	case which < tf[StructTfIdx]:
		{
			if toodeep {
				panic("should not be here")
			}
			var sp structparm
			ns := len(f.structdefs)
			sp.sname = fmt.Sprintf("StructF%dS%d", f.idx, ns)
			sp.qname = fmt.Sprintf("%s.StructF%dS%d",
				s.checkerPkg(pidx), f.idx, ns)
			f.structdefs = append(f.structdefs, sp)
			tnf := int64(s.tunables.nStructFields) / int64(depth+1)
			nf := int(s.wr.Intn(tnf))
			for range nf {
				fp := s.GenParm(f, depth+1, false, pidx)
				skComp := tunables.doSkipCompare &&
					uint8(s.wr.Intn(100)) < s.tunables.skipCompareFraction
				if skComp && checkableElements(fp) != 0 {
					fp.SetSkipCompare(SkipAll)
				}
				sp.fields = append(sp.fields, fp)
			}
			f.structdefs[ns] = sp
			retval = &sp
		}
	case which < tf[ArrayTfIdx]:
		{
			if toodeep {
				panic("should not be here")
			}
			var ap arrayparm
			ns := len(f.arraydefs)
			nel := uint8(s.wr.Intn(int64(s.tunables.nArrayElements)))
			issl := uint8(s.wr.Intn(100)) < s.tunables.sliceFraction
			ap.aname = fmt.Sprintf("ArrayF%dS%dE%d", f.idx, ns, nel)
			ap.qname = fmt.Sprintf("%s.ArrayF%dS%dE%d", s.checkerPkg(pidx),
				f.idx, ns, nel)
			f.arraydefs = append(f.arraydefs, ap)
			ap.nelements = nel
			ap.slice = issl
			ap.eltype = s.GenParm(f, depth+1, false, pidx)
			ap.eltype.SetBlank(false)
			skComp := tunables.doSkipCompare &&
				uint8(s.wr.Intn(100)) < s.tunables.skipCompareFraction
			if skComp && checkableElements(ap.eltype) != 0 {
				if issl {
					ap.SetSkipCompare(SkipPayload)
				}
			}
			f.arraydefs[ns] = ap
			retval = &ap
		}
	case which < tf[MapTfIdx]:
		{
			if toodeep {
				panic("should not be here")
			}
			var mp mapparm
			ns := len(f.mapdefs)

			// append early, since calls below might also append
			f.mapdefs = append(f.mapdefs, mp)
			f.mapkeytmps = append(f.mapkeytmps, "")
			f.mapkeytypes = append(f.mapkeytypes, mp.keytype)
			mp.aname = fmt.Sprintf("MapF%dM%d", f.idx, ns)
			if f.mapkeyts == "" {
				f.mapkeyts = fmt.Sprintf("MapKeysF%d", f.idx)
			}
			mp.qname = fmt.Sprintf("%s.MapF%dM%d", s.checkerPkg(pidx),
				f.idx, ns)
			mkt := fmt.Sprintf("Mk%dt%d", f.idx, ns)
			mp.keytmp = mkt
			mk := s.GenMapKeyType(f, depth+1, pidx)
			mp.keytype = mk
			mp.valtype = s.GenParm(f, depth+1, false, pidx)
			mp.valtype.SetBlank(false)
			mp.keytype.SetBlank(false)
			// now update the previously appended placeholders
			f.mapdefs[ns] = mp
			f.mapkeytypes[ns] = mk
			f.mapkeytmps[ns] = mkt
			retval = &mp
		}
	case which < tf[PointerTfIdx]:
		{
			if toodeep {
				panic("should not be here")
			}
			pp := mkPointerParm(s.GenParm(f, depth+1, false, pidx))
			retval = &pp
		}
	case which < tf[NumericTfIdx]:
		{
			var ip numparm
			ip.tag = s.intFlavor()
			ip.widthInBits = s.intBits()
			if mkctl {
				ip.ctl = true
			}
			retval = &ip
		}
	case which < tf[FloatTfIdx]:
		{
			var fp numparm
			fp.tag = "float"
			fp.widthInBits = s.floatBits()
			retval = &fp
		}
	case which < tf[ComplexTfIdx]:
		{
			var fp numparm
			fp.tag = "complex"
			fp.widthInBits = s.floatBits() * 2
			retval = &fp
		}
	case which < tf[ByteTfIdx]:
		{
			var bp numparm
			bp.tag = "byte"
			bp.widthInBits = 8
			retval = &bp
		}
	case which < tf[StringTfIdx]:
		{
			var sp stringparm
			sp.tag = "string"
			skComp := tunables.doSkipCompare &&
				uint8(s.wr.Intn(100)) < s.tunables.skipCompareFraction
			if skComp {
				sp.SetSkipCompare(SkipPayload)
			}
			retval = &sp
		}
	default:
		{
			// fallback
			var ip numparm
			ip.tag = "uint"
			ip.widthInBits = 8
			retval = &ip
		}
	}
	if !mkctl {
		retval.SetBlank(isblank)
	}
	retval.SetAddrTaken(addrTaken)
	retval.SetIsGenVal(isGenValFunc)
	return retval
}

func (s *genstate) GenReturn(f *funcdef, depth int, pidx int) parm {
	return s.GenParm(f, depth, false, pidx)
}

// GenFunc cooks up the random signature (and other attributes) of a
// given checker function, returning a funcdef object that describes
// the new fcn.
func (s *genstate) GenFunc(fidx int, pidx int) *funcdef {
	f := new(funcdef)
	f.idx = fidx
	numParams := int(s.wr.Intn(int64(1 + int(s.tunables.nParmRange))))
	numReturns := int(s.wr.Intn(int64(1 + int(s.tunables.nReturnRange))))
	f.recur = uint8(s.wr.Intn(100)) < s.tunables.recurPerc
	f.isMethod = uint8(s.wr.Intn(100)) < s.tunables.methodPerc
	genReceiverType := func() {
		// Receiver type can't be pointer type. Temporarily update
		// tunables to eliminate that possibility.
		s.pushTunables()
		defer s.popTunables()
		s.precludeSelectedTypes(PointerTfIdx)
		target := s.GenParm(f, 0, false, pidx)
		target.SetBlank(false)
		f.receiver = s.makeTypedefParm(f, target, pidx)
		if f.receiver.IsBlank() {
			f.recur = false
		}
	}
	if f.isMethod {
		genReceiverType()
	}
	needControl := f.recur
	f.dodefc = uint8(s.wr.Intn(100))
	pTaken := uint8(s.wr.Intn(100)) < s.tunables.takenFraction
	for range numParams {
		newparm := s.GenParm(f, 0, needControl, pidx)
		if !pTaken {
			newparm.SetAddrTaken(notAddrTaken)
		}
		if newparm.IsControl() {
			needControl = false
		}
		f.params = append(f.params, newparm)
		f.dodefp = append(f.dodefp, uint8(s.wr.Intn(100)))
	}
	if f.recur && needControl {
		f.recur = false
	}

	rTaken := uint8(s.wr.Intn(100)) < s.tunables.takenFraction
	for range numReturns {
		r := s.GenReturn(f, 0, pidx)
		if !rTaken {
			r.SetAddrTaken(notAddrTaken)
		}
		f.returns = append(f.returns, r)
	}
	spw := uint(s.wr.Intn(11))
	rstack := max(1<<spw, 4)
	f.rstack = rstack
	return f
}

func genDeref(p parm) (parm, string) {
	curp := p
	var star strings.Builder
	for {
		if pp, ok := curp.(*pointerparm); ok {
			star.WriteString("*")
			curp = pp.totype
		} else {
			return curp, star.String()
		}
	}
}

func (s *genstate) eqFuncRef(f *funcdef, t parm, caller bool) string {
	cp := ""
	if f.mapkeyts != "" {
		cp = "mkt."
	} else if caller {
		cp = s.checkerPkg(s.pkidx) + "."
	}
	return cp + "Equal" + t.TypeName()
}

// emitCompareFunc creates an 'equals' function for a specific
// generated type (this is basically a way to compare objects that
// contain pointer fields / pointery things).
func (s *genstate) emitCompareFunc(f *funcdef, b *bytes.Buffer, p parm) {
	if !p.HasPointer() {
		return
	}

	tn := p.TypeName()
	b.WriteString(fmt.Sprintf("// equal func for %s\n", tn))
	b.WriteString("//go:noinline\n")
	rcvr := ""
	if f.mapkeyts != "" {
		rcvr = fmt.Sprintf("(mkt *%s) ", f.mapkeyts)
	}
	b.WriteString(fmt.Sprintf("func %sEqual%s(left %s, right %s) bool {\n", rcvr, tn, tn, tn))
	b.WriteString("  return ")
	numel := p.NumElements()
	ncmp := 0
	for i := range numel {
		lelref, lelparm := p.GenElemRef(i, "left")
		relref, _ := p.GenElemRef(i, "right")
		if lelref == "" || lelref == "_" {
			continue
		}
		basep, star := genDeref(lelparm)
		// Handle *p where p is an empty struct.
		if basep.NumElements() == 0 {
			continue
		}
		if ncmp != 0 {
			b.WriteString("  && ")
		}
		ncmp++
		if basep.HasPointer() {
			efn := s.eqFuncRef(f, basep, false)
			b.WriteString(fmt.Sprintf(" %s(%s%s, %s%s)", efn, star, lelref, star, relref))
		} else {
			b.WriteString(fmt.Sprintf("%s%s == %s%s", star, lelref, star, relref))
		}
	}
	if ncmp == 0 {
		b.WriteString("true")
	}
	b.WriteString("\n}\n\n")
}

// emitStructAndArrayDefs writes out definitions of the random types
// we happened to cook up while generating code for a specific
// function pair.
func (s *genstate) emitStructAndArrayDefs(f *funcdef, b *bytes.Buffer) {
	for _, str := range f.structdefs {
		b.WriteString(fmt.Sprintf("type %s struct {\n", str.sname))
		for fi, sp := range str.fields {
			sp.Declare(b, "  "+str.FieldName(fi), "\n", false)
		}
		b.WriteString("}\n\n")
		s.emitCompareFunc(f, b, &str)
	}
	for _, a := range f.arraydefs {
		elems := fmt.Sprintf("%d", a.nelements)
		if a.slice {
			elems = ""
		}
		b.WriteString(fmt.Sprintf("type %s [%s]%s\n\n", a.aname,
			elems, a.eltype.TypeName()))
		s.emitCompareFunc(f, b, &a)
	}
	for _, a := range f.mapdefs {
		b.WriteString(fmt.Sprintf("type %s map[%s]%s\n\n", a.aname,
			a.keytype.TypeName(), a.valtype.TypeName()))
		s.emitCompareFunc(f, b, &a)
	}
	for _, td := range f.typedefs {
		b.WriteString(fmt.Sprintf("type %s %s\n\n", td.aname,
			td.target.TypeName()))
		s.emitCompareFunc(f, b, &td)
	}
	if f.mapkeyts != "" {
		b.WriteString(fmt.Sprintf("type %s struct {\n", f.mapkeyts))
		for i := range f.mapkeytypes {
			f.mapkeytypes[i].Declare(b, "  "+f.mapkeytmps[i], "\n", false)
		}
		b.WriteString("}\n\n")
	}
}

// GenValue method of genstate wraps the parm method of the same
// name, but optionally returns a call to a function to produce
// the value as opposed to a literal value.
func (s *genstate) GenValue(f *funcdef, p parm, value int, caller bool) (string, int) {
	var valstr string
	valstr, value = p.GenValue(s, f, value, caller)
	if !s.tunables.doFuncCallValues || !p.IsGenVal() || caller {
		return valstr, value
	}

	mkInvoc := func(fname string) string {
		meth := ""
		if f.mapkeyts != "" {
			meth = "mkt."
		}
		return fmt.Sprintf("%s%s()", meth, fname)
	}

	b := bytes.NewBuffer(nil)
	p.Declare(b, "x", "", false)
	h := sha1.New()
	h.Write([]byte(valstr))
	h.Write(b.Bytes())
	if f.mapkeyts != "" {
		h.Write([]byte(f.mapkeyts))
	}
	h.Write(b.Bytes())
	bs := h.Sum(nil)
	hashstr := fmt.Sprintf("%x", bs)
	b.WriteString(hashstr)
	tag := b.String()
	fname, ok := s.genvalFuncs[tag]
	if ok {
		return mkInvoc(fname), value
	}

	fname = fmt.Sprintf("genval_%d", len(s.genvalFuncs))
	s.newGenvalFuncs = append(s.newGenvalFuncs, funcdesc{p: p, name: fname, tag: tag, payload: valstr})
	s.genvalFuncs[tag] = fname
	return mkInvoc(fname), value
}

func (s *genstate) emitMapKeyTmps(f *funcdef, b *bytes.Buffer, pidx int, value int, caller bool) int {
	if f.mapkeyts == "" {
		return value
	}
	// map key tmps
	cp := ""
	if caller {
		cp = s.checkerPkg(pidx) + "."
	}
	b.WriteString("  var mkt " + cp + f.mapkeyts + "\n")
	for i, t := range f.mapkeytypes {
		var keystr string
		keystr, value = s.GenValue(f, t, value, caller)
		tname := f.mapkeytmps[i]
		b.WriteString(fmt.Sprintf("  %s := %s\n", tname, keystr))
		b.WriteString(fmt.Sprintf("  mkt.%s = %s\n", tname, tname))
	}
	return value
}

func (s *genstate) emitCheckReturnsInCaller(f *funcdef, b *bytes.Buffer, pidx int, reflectCall bool) {
	cm := f.complexityMeasure()
	rvalp := func(ri int) string {
		if reflectCall {
			return fmt.Sprintf("rr%dv", ri)
		}
		return fmt.Sprintf("r%d", ri)
	}
	failTag := "\"return\""
	if reflectCall {
		failTag = "\"reflect return\""
	}
	for ri, rp := range f.returns {
		if reflectCall {
			b.WriteString(fmt.Sprintf("  rr%di := rvslice[%d].Interface()\n", ri, ri))
			b.WriteString(fmt.Sprintf("  rr%dv:= rr%di.(", ri, ri))
			rp.Declare(b, "", "", true)
			b.WriteString(")\n")
		}
		pfc := ""
		curp, star := genDeref(rp)
		// Handle *p where p is an empty struct.
		if curp.NumElements() == 0 {
			b.WriteString(fmt.Sprintf("  _, _ = %s, c%d // zero size\n", rvalp(ri), ri))
			continue
		}
		if star != "" {
			pfc = fmt.Sprintf("ParamFailCount[%d] == 0 && ", pidx)
		}
		if curp.HasPointer() {
			efn := "!" + s.eqFuncRef(f, curp, true)
			b.WriteString(fmt.Sprintf("  if %s%s(%s%s, %sc%d) {\n", pfc, efn, star, rvalp(ri), star, ri))
		} else {
			b.WriteString(fmt.Sprintf("  if %s%s%s != %sc%d {\n", pfc, star, rvalp(ri), star, ri))
		}
		b.WriteString(fmt.Sprintf("    NoteFailure(%d, %d, %d, \"%s\", %s, %d, true, uint64(0))\n", cm, pidx, f.idx, s.checkerPkg(pidx), failTag, ri))
		b.WriteString("  }\n")
	}
}

func (s *genstate) emitCaller(f *funcdef, b *bytes.Buffer, pidx int) {

	b.WriteString(fmt.Sprintf("func %s%d(mode string) {\n", CallerName, f.idx))

	b.WriteString(fmt.Sprintf("  BeginFcn(%d)\n", pidx))

	if s.EmitBad == 1 {
		if s.BadPackageIdx == pidx && s.BadFuncIdx == f.idx {
			b.WriteString("  bad code here, should cause build failure <<==\n")
		}
	}

	var value int = 1

	s.wr.Checkpoint("before mapkeytmps")
	value = s.emitMapKeyTmps(f, b, pidx, value, true)

	// generate return constants
	s.wr.Checkpoint("before return constants")
	for ri, r := range f.returns {
		rc := fmt.Sprintf("c%d", ri)
		value = s.emitVarAssign(f, b, r, rc, value, true)
	}

	// generate param constants
	s.wr.Checkpoint("before param constants")
	for pi, p := range f.params {
		verb(4, "emitCaller gen p%d value=%d", pi, value)
		if p.IsControl() {
			_ = uint8(s.wr.Intn(100)) < 50
			p.Declare(b, fmt.Sprintf("  var p%d ", pi), " = 10\n", true)
		} else {
			pc := fmt.Sprintf("p%d", pi)
			value = s.emitVarAssign(f, b, p, pc, value, true)
		}
		f.values = append(f.values, value)
	}

	// generate receiver constant if applicable
	if f.isMethod {
		s.wr.Checkpoint("before receiver constant")
		f.receiver.Declare(b, "  var rcvr", "\n", true)
		valstr, value := s.GenValue(f, f.receiver, value, true)
		b.WriteString(fmt.Sprintf("  rcvr = %s\n", valstr))
		f.values = append(f.values, value)
	}

	b.WriteString(fmt.Sprintf("  Mode[%d] = \"\"\n", pidx))

	// calling code
	b.WriteString(fmt.Sprintf("  // %d returns %d params\n",
		len(f.returns), len(f.params)))
	if s.ForceStackGrowth {
		b.WriteString("  hackStack() // force stack growth on next call\n")
	}
	b.WriteString("  if mode == \"normal\" {\n")
	b.WriteString("  ")
	for ri := range f.returns {
		writeCom(b, ri)
		b.WriteString(fmt.Sprintf("r%d", ri))
	}
	if len(f.returns) > 0 {
		b.WriteString(" := ")
	}
	pref := s.checkerPkg(pidx)
	if f.isMethod {
		pref = "rcvr"
	}
	b.WriteString(fmt.Sprintf("%s.Test%d(", pref, f.idx))
	for pi := range f.params {
		writeCom(b, pi)
		b.WriteString(fmt.Sprintf("p%d", pi))
	}
	b.WriteString(")\n")

	// check values returned (normal call case)
	s.emitCheckReturnsInCaller(f, b, pidx, false /* not a reflect call */)
	b.WriteString("  }") // end of 'if normal call' block
	if s.tunables.doReflectCall {
		b.WriteString("else {\n") // beginning of reflect call block
		// now make the same call via reflection
		b.WriteString("  // same call via reflection\n")
		b.WriteString(fmt.Sprintf("  Mode[%d] = \"reflect\"\n", pidx))
		if f.isMethod {
			b.WriteString("  rcv := reflect.ValueOf(rcvr)\n")
			b.WriteString(fmt.Sprintf("  rc := rcv.MethodByName(\"Test%d\")\n", f.idx))
		} else {
			b.WriteString(fmt.Sprintf("  rc := reflect.ValueOf(%s.Test%d)\n",
				s.checkerPkg(pidx), f.idx))
		}
		b.WriteString("  ")
		if len(f.returns) > 0 {
			b.WriteString("rvslice := ")
		}
		b.WriteString("  rc.Call([]reflect.Value{")
		for pi := range f.params {
			writeCom(b, pi)
			b.WriteString(fmt.Sprintf("reflect.ValueOf(p%d)", pi))
		}
		b.WriteString("})\n")

		// check values returned (reflect call case)
		s.emitCheckReturnsInCaller(f, b, pidx, true /* is a reflect call */)
		b.WriteString("}\n") // end of reflect call block
	}

	b.WriteString(fmt.Sprintf("\n  EndFcn(%d)\n", pidx))

	b.WriteString("}\n\n")
}

func checkableElements(p parm) int {
	if p.IsBlank() {
		return 0
	}
	sp, isstruct := p.(*structparm)
	if isstruct {
		s := 0
		for fi := range sp.fields {
			s += checkableElements(sp.fields[fi])
		}
		return s
	}
	ap, isarray := p.(*arrayparm)
	if isarray {
		if ap.nelements == 0 {
			return 0
		}
		return int(ap.nelements) * checkableElements(ap.eltype)
	}
	return 1
}

// funcdesc describes an auto-generated helper function or global
// variable, such as an allocation function (returns new(T)) or a
// pointer assignment function (assigns value of T to type *T). Here
// 'p' is a param type T, 'pp' is a pointer type *T, 'name' is the
// name within the generated code of the function or variable and
// 'tag' is a descriptive tag used to look up the entity in a map (so
// that we don't have to emit multiple copies of a function that
// assigns int to *int, for example).
type funcdesc struct {
	p       parm
	pp      parm
	name    string
	tag     string
	payload string
}

func (s *genstate) emitDerefFuncs(b *bytes.Buffer, emit bool) {
	b.WriteString("// dereference helpers\n")
	for _, fd := range s.newDerefFuncs {
		if !emit {
			b.WriteString(fmt.Sprintf("\n// skip derefunc %s\n", fd.name))
			delete(s.derefFuncs, fd.tag)
			continue
		}
		b.WriteString("\n//go:noinline\n")
		b.WriteString(fmt.Sprintf("func %s(", fd.name))
		fd.pp.Declare(b, "x", "", false)
		b.WriteString(") ")
		fd.p.Declare(b, "", "", false)
		b.WriteString(" {\n")
		b.WriteString("  return *x\n")
		b.WriteString("}\n")
	}
	s.newDerefFuncs = nil
}

func (s *genstate) emitAssignFuncs(b *bytes.Buffer, emit bool) {
	b.WriteString("// assign helpers\n")
	for _, fd := range s.newAssignFuncs {
		if !emit {
			b.WriteString(fmt.Sprintf("\n// skip assignfunc %s\n", fd.name))
			delete(s.assignFuncs, fd.tag)
			continue
		}
		b.WriteString("\n//go:noinline\n")
		b.WriteString(fmt.Sprintf("func %s(", fd.name))
		fd.pp.Declare(b, "x", "", false)
		b.WriteString(", ")
		fd.p.Declare(b, "v", "", false)
		b.WriteString(") {\n")
		b.WriteString("  *x = v\n")
		b.WriteString("}\n")
	}
	s.newAssignFuncs = nil
}

func (s *genstate) emitNewFuncs(b *bytes.Buffer, emit bool) {
	b.WriteString("// 'new' funcs\n")
	for _, fd := range s.newAllocFuncs {
		if !emit {
			b.WriteString(fmt.Sprintf("\n// skip newfunc %s\n", fd.name))
			delete(s.allocFuncs, fd.tag)
			continue
		}
		b.WriteString("\n//go:noinline\n")
		b.WriteString(fmt.Sprintf("func %s(", fd.name))
		fd.p.Declare(b, "i", "", false)
		b.WriteString(") ")
		fd.pp.Declare(b, "", "", false)
		b.WriteString(" {\n")
		b.WriteString("  x := new(")
		fd.p.Declare(b, "", "", false)
		b.WriteString(")\n")
		b.WriteString("  *x = i\n")
		b.WriteString("  return x\n")
		b.WriteString("}\n\n")
	}
	s.newAllocFuncs = nil
}

func (s *genstate) emitGlobalVars(b *bytes.Buffer, emit bool) {
	b.WriteString("// global vars\n")
	for _, fd := range s.newGlobVars {
		if !emit {
			b.WriteString(fmt.Sprintf("\n// skip gvar %s\n", fd.name))
			delete(s.globVars, fd.tag)
			continue
		}
		b.WriteString("var ")
		fd.pp.Declare(b, fd.name, "", false)
		b.WriteString("\n")
	}
	s.newGlobVars = nil
	b.WriteString("\n")
}

func (s *genstate) emitGenValFuncs(f *funcdef, b *bytes.Buffer, emit bool) {
	b.WriteString("// genval helpers\n")
	for _, fd := range s.newGenvalFuncs {
		if !emit {
			b.WriteString(fmt.Sprintf("\n// skip genvalfunc %s\n", fd.name))
			delete(s.genvalFuncs, fd.tag)
			continue
		}
		b.WriteString("\n//go:noinline\n")
		rcvr := ""
		if f.mapkeyts != "" {
			rcvr = fmt.Sprintf("(mkt *%s) ", f.mapkeyts)
		}
		b.WriteString(fmt.Sprintf("func %s%s() ", rcvr, fd.name))
		fd.p.Declare(b, "", "", false)
		b.WriteString(" {\n")
		if f.mapkeyts != "" {
			contained := containedParms(fd.p)
			for _, cp := range contained {
				mp, ismap := cp.(*mapparm)
				if ismap {
					b.WriteString(fmt.Sprintf("  %s := mkt.%s\n",
						mp.keytmp, mp.keytmp))
					b.WriteString(fmt.Sprintf("  _ = %s\n", mp.keytmp))
				}
			}
		}
		b.WriteString(fmt.Sprintf("  return %s\n", fd.payload))
		b.WriteString("}\n")
	}
	s.newGenvalFuncs = nil
}

func (s *genstate) emitAddrTakenHelpers(f *funcdef, b *bytes.Buffer, emit bool) {
	b.WriteString("// begin addr taken helpers\n")
	s.emitDerefFuncs(b, emit)
	s.emitAssignFuncs(b, emit)
	s.emitNewFuncs(b, emit)
	s.emitGlobalVars(b, emit)
	s.emitGenValFuncs(f, b, emit)
	b.WriteString("// end addr taken helpers\n")
}

func (s *genstate) genGlobVar(p parm) string {
	var pp parm
	ppp := mkPointerParm(p)
	pp = &ppp
	b := bytes.NewBuffer(nil)
	pp.Declare(b, "gv", "", false)
	tag := b.String()
	gv, ok := s.globVars[tag]
	if ok {
		return gv
	}
	gv = fmt.Sprintf("gvar_%d", len(s.globVars))
	s.newGlobVars = append(s.newGlobVars, funcdesc{pp: pp, p: p, name: gv, tag: tag})
	s.globVars[tag] = gv
	return gv
}

func (s *genstate) genParamDerefFunc(p parm) string {
	var pp parm
	ppp := mkPointerParm(p)
	pp = &ppp
	b := bytes.NewBuffer(nil)
	pp.Declare(b, "x", "", false)
	tag := b.String()
	f, ok := s.derefFuncs[tag]
	if ok {
		return f
	}
	f = fmt.Sprintf("deref_%d", len(s.derefFuncs))
	s.newDerefFuncs = append(s.newDerefFuncs, funcdesc{pp: pp, p: p, name: f, tag: tag})
	s.derefFuncs[tag] = f
	return f
}

func (s *genstate) genAssignFunc(p parm) string {
	var pp parm
	ppp := mkPointerParm(p)
	pp = &ppp
	b := bytes.NewBuffer(nil)
	pp.Declare(b, "x", "", false)
	tag := b.String()
	f, ok := s.assignFuncs[tag]
	if ok {
		return f
	}
	f = fmt.Sprintf("retassign_%d", len(s.assignFuncs))
	s.newAssignFuncs = append(s.newAssignFuncs, funcdesc{pp: pp, p: p, name: f, tag: tag})
	s.assignFuncs[tag] = f
	return f
}

func (s *genstate) genAllocFunc(p parm) string {
	var pp parm
	ppp := mkPointerParm(p)
	pp = &ppp
	b := bytes.NewBuffer(nil)
	pp.Declare(b, "x", "", false)
	tag := b.String()
	f, ok := s.allocFuncs[tag]
	if ok {
		return f
	}
	f = fmt.Sprintf("New_%d", len(s.allocFuncs))
	s.newAllocFuncs = append(s.newAllocFuncs, funcdesc{pp: pp, p: p, name: f, tag: tag})
	s.allocFuncs[tag] = f
	return f
}

func (s *genstate) genParamRef(p parm, idx int) string {
	switch p.AddrTaken() {
	case notAddrTaken:
		return fmt.Sprintf("p%d", idx)
	case addrTakenSimple, addrTakenHeap:
		return fmt.Sprintf("(*ap%d)", idx)
	case addrTakenPassed:
		f := s.genParamDerefFunc(p)
		return fmt.Sprintf("%s(ap%d)", f, idx)
	default:
		panic("bad")
	}
}

func (s *genstate) genReturnAssign(b *bytes.Buffer, r parm, idx int, val string) {
	switch r.AddrTaken() {
	case notAddrTaken:
		b.WriteString(fmt.Sprintf("  r%d = %s\n", idx, val))
	case addrTakenSimple, addrTakenHeap:
		b.WriteString(fmt.Sprintf("  (*ar%d) = %v\n", idx, val))
	case addrTakenPassed:
		f := s.genAssignFunc(r)
		b.WriteString(fmt.Sprintf("  %s(ar%d, %v)\n", f, idx, val))
	default:
		panic("bad")
	}
}

func (s *genstate) emitParamElemCheck(f *funcdef, b *bytes.Buffer, p parm, pvar string, cvar string, paramidx int, elemidx int) {
	if p.SkipCompare() == SkipAll {
		b.WriteString(fmt.Sprintf("  // selective skip of %s\n", pvar))
		b.WriteString(fmt.Sprintf("  _ = %s\n", cvar))
		return
	} else if p.SkipCompare() == SkipPayload {
		switch p.(type) {
		case *stringparm, *arrayparm:
			b.WriteString(fmt.Sprintf("  if len(%s) != len(%s) { // skip payload\n",
				pvar, cvar))
		default:
			panic("should never happen")
		}
	} else {
		basep, star := genDeref(p)
		// Handle *p where p is an empty struct.
		if basep.NumElements() == 0 {
			return
		}
		if basep.HasPointer() {
			efn := s.eqFuncRef(f, basep, false)
			b.WriteString(fmt.Sprintf("  if !%s(%s%s, %s%s) {\n",
				efn, star, pvar, star, cvar))
		} else {
			b.WriteString(fmt.Sprintf("  if %s%s != %s%s {\n",
				star, pvar, star, cvar))
		}
	}
	cm := f.complexityMeasure()
	b.WriteString(fmt.Sprintf("    NoteFailureElem(%d, %d, %d, \"%s\", \"parm\", %d, %d, false, pad[0])\n", cm, s.pkidx, f.idx, s.checkerPkg(s.pkidx), paramidx, elemidx))
	b.WriteString("    return\n")
	b.WriteString("  }\n")
}

func (s *genstate) emitParamChecks(f *funcdef, b *bytes.Buffer, pidx int, value int) (int, bool) {
	var valstr string
	haveControl := false
	dangling := []int{}
	for pi, p := range f.params {
		verb(4, "emitting parmcheck p%d numel=%d pt=%s value=%d",
			pi, p.NumElements(), p.TypeName(), value)
		// To balance code in caller
		_ = uint8(s.wr.Intn(100)) < 50
		if p.IsControl() {
			b.WriteString(fmt.Sprintf("  if %s == 0 {\n",
				s.genParamRef(p, pi)))
			s.emitReturn(f, b, false)
			b.WriteString("  }\n")
			haveControl = true

		} else if p.IsBlank() {
			valstr, value = s.GenValue(f, p, value, false)
			if f.recur {
				b.WriteString(fmt.Sprintf("  brc%d := %s\n", pi, valstr))
			} else {
				b.WriteString(fmt.Sprintf("  _ = %s\n", valstr))
			}
		} else {
			numel := p.NumElements()
			cel := checkableElements(p)
			for i := range numel {
				verb(4, "emitting check-code for p%d el %d value=%d", pi, i, value)
				elref, elparm := p.GenElemRef(i, s.genParamRef(p, pi))
				valstr, value = s.GenValue(f, elparm, value, false)
				if elref == "" || elref == "_" || cel == 0 {
					b.WriteString(fmt.Sprintf("  // blank skip: %s\n", valstr))
					continue
				} else {
					basep, _ := genDeref(elparm)
					// Handle *p where p is an empty struct.
					if basep.NumElements() == 0 {
						continue
					}
					cvar := fmt.Sprintf("p%df%dc", pi, i)
					b.WriteString(fmt.Sprintf("  %s := %s\n", cvar, valstr))
					s.emitParamElemCheck(f, b, elparm, elref, cvar, pi, i)
				}
			}
			if p.AddrTaken() != notAddrTaken {
				dangling = append(dangling, pi)
			}
		}
		if value != f.values[pi] {
			fmt.Fprintf(os.Stderr, "internal error: checker/caller value mismatch after emitting param %d func Test%d pkg %s: caller %d checker %d\n", pi, f.idx, s.checkerPkg(pidx), f.values[pi], value)
			s.errs++
		}
	}
	for _, pi := range dangling {
		b.WriteString(fmt.Sprintf("  _ = ap%d // ref\n", pi))
	}

	// receiver value check
	if f.isMethod {
		numel := f.receiver.NumElements()
		for i := range numel {
			verb(4, "emitting check-code for rcvr el %d value=%d", i, value)
			elref, elparm := f.receiver.GenElemRef(i, "rcvr")
			valstr, value = s.GenValue(f, elparm, value, false)
			if elref == "" || strings.HasPrefix(elref, "_") || f.receiver.IsBlank() {
				verb(4, "empty skip rcvr el %d", i)
				continue
			} else {

				basep, _ := genDeref(elparm)
				// Handle *p where p is an empty struct.
				if basep.NumElements() == 0 {
					continue
				}
				cvar := fmt.Sprintf("rcvrf%dc", i)
				b.WriteString(fmt.Sprintf("  %s := %s\n", cvar, valstr))
				s.emitParamElemCheck(f, b, elparm, elref, cvar, -1, i)
			}
		}
	}

	return value, haveControl
}

// emitDeferChecks creates code like
//
//	defer func(...args...) {
//	  check arg
//	  check param
//	}(...)
//
// where we randomly choose to either pass a param through to the
// function literal, or have the param captured by the closure, then
// check its value in the defer.
func (s *genstate) emitDeferChecks(f *funcdef, b *bytes.Buffer, value int) int {

	if len(f.params) == 0 {
		return value
	}

	// make a pass through the params and randomly decide which will be passed into the func.
	passed := []bool{}
	for i := range f.params {
		p := f.dodefp[i] < 50
		passed = append(passed, p)
	}

	b.WriteString("  defer func(")
	pc := 0
	for pi, p := range f.params {
		if p.IsControl() || p.IsBlank() {
			continue
		}
		if passed[pi] {
			writeCom(b, pc)
			n := fmt.Sprintf("p%d", pi)
			p.Declare(b, n, "", false)
			pc++
		}
	}
	b.WriteString(") {\n")

	for pi, p := range f.params {
		if p.IsControl() || p.IsBlank() {
			continue
		}
		which := "passed"
		if !passed[pi] {
			which = "captured"
		}
		b.WriteString("  // check parm " + which + "\n")
		numel := p.NumElements()
		cel := checkableElements(p)
		for i := range numel {
			elref, elparm := p.GenElemRef(i, s.genParamRef(p, pi))
			if elref == "" || elref == "_" || cel == 0 {
				verb(4, "empty skip p%d el %d", pi, i)
				continue
			} else {
				basep, _ := genDeref(elparm)
				// Handle *p where p is an empty struct.
				if basep.NumElements() == 0 {
					continue
				}
				cvar := fmt.Sprintf("p%df%dc", pi, i)
				s.emitParamElemCheck(f, b, elparm, elref, cvar, pi, i)
			}
		}
	}
	b.WriteString("  } (")
	pc = 0
	for pi, p := range f.params {
		if p.IsControl() || p.IsBlank() {
			continue
		}
		if passed[pi] {
			writeCom(b, pc)
			b.WriteString(fmt.Sprintf("p%d", pi))
			pc++
		}
	}
	b.WriteString(")\n\n")

	return value
}

func (s *genstate) emitVarAssign(f *funcdef, b *bytes.Buffer, r parm, rname string, value int, caller bool) int {
	var valstr string
	isassign := uint8(s.wr.Intn(100)) < 50
	if rmp, ismap := r.(*mapparm); ismap && isassign {
		// emit: var m ... ; m[k] = v
		r.Declare(b, "  "+rname+" := make(", ")\n", caller)
		valstr, value = s.GenValue(f, rmp.valtype, value, caller)
		b.WriteString(fmt.Sprintf("  %s[mkt.%s] = %s\n",
			rname, rmp.keytmp, valstr))
	} else {
		// emit r = c
		valstr, value = s.GenValue(f, r, value, caller)
		b.WriteString(fmt.Sprintf("  %s := %s\n", rname, valstr))
	}
	return value
}

func (s *genstate) emitChecker(f *funcdef, b *bytes.Buffer, pidx int, emit bool) {
	verb(4, "emitting struct and array defs")
	s.emitStructAndArrayDefs(f, b)
	b.WriteString(fmt.Sprintf("// %d returns %d params\n", len(f.returns), len(f.params)))
	if s.Pragma != "" {
		b.WriteString("//go:" + s.Pragma + "\n")
	}
	b.WriteString("//go:noinline\n")

	b.WriteString("func")

	if f.isMethod {
		b.WriteString(" (")
		n := "rcvr"
		if f.receiver.IsBlank() {
			n = "_"
		}
		f.receiver.Declare(b, n, "", false)
		b.WriteString(")")
	}

	b.WriteString(fmt.Sprintf(" Test%d(", f.idx))

	verb(4, "emitting checker p%d/Test%d", pidx, f.idx)

	// params
	for pi, p := range f.params {
		writeCom(b, pi)
		n := fmt.Sprintf("p%d", pi)
		if p.IsBlank() {
			n = "_"
		}
		p.Declare(b, n, "", false)
	}
	b.WriteString(") ")

	// returns
	if len(f.returns) > 0 {
		b.WriteString("(")
	}
	for ri, r := range f.returns {
		writeCom(b, ri)
		r.Declare(b, fmt.Sprintf("r%d", ri), "", false)
	}
	if len(f.returns) > 0 {
		b.WriteString(")")
	}
	b.WriteString(" {\n")

	// local storage
	b.WriteString("  // consume some stack space, so as to trigger morestack\n")
	b.WriteString(fmt.Sprintf("  var pad [%d]uint64\n", f.rstack))
	b.WriteString(fmt.Sprintf("  pad[FailCount[%d] & 0x1]++\n", pidx))

	value := 1

	// generate map key tmps
	s.wr.Checkpoint("before map key temps")
	value = s.emitMapKeyTmps(f, b, pidx, value, false)

	// generate return constants
	s.wr.Checkpoint("before return constants")
	for ri, r := range f.returns {
		rc := fmt.Sprintf("rc%d", ri)
		value = s.emitVarAssign(f, b, r, rc, value, false)
	}

	// Prepare to reference params/returns by address.
	lists := [][]parm{f.params, f.returns}
	names := []string{"p", "r"}
	var aCounts [2]int
	for i, lst := range lists {
		for pi, p := range lst {
			if p.AddrTaken() == notAddrTaken {
				continue
			}
			aCounts[i]++
			n := names[i]
			b.WriteString(fmt.Sprintf("  a%s%d := &%s%d\n", n, pi, n, pi))
			if p.AddrTaken() == addrTakenHeap {
				gv := s.genGlobVar(p)
				b.WriteString(fmt.Sprintf("  %s = a%s%d\n", gv, n, pi))
			}
		}
	}

	if s.EmitBad == 2 {
		if s.BadPackageIdx == pidx && s.BadFuncIdx == f.idx {
			b.WriteString("  // force runtime failure here (debugging)\n")
			b.WriteString(fmt.Sprintf("    NoteFailure(%d, %d, %d, \"%s\", \"artificial\", %d, true, uint64(0))\n", f.complexityMeasure(), pidx, f.idx, s.checkerPkg(pidx), 0))
		}
	}

	// parameter checking code
	var haveControl bool
	s.wr.Checkpoint("before param checks")
	value, haveControl = s.emitParamChecks(f, b, pidx, value)

	// defer testing
	if s.tunables.doDefer && f.dodefc < s.tunables.deferFraction {
		s.wr.Checkpoint("before defer checks")
		_ = s.emitDeferChecks(f, b, value)
	}

	// returns
	s.emitReturn(f, b, haveControl)

	b.WriteString(fmt.Sprintf("  // %d addr-taken params, %d addr-taken returns\n",
		aCounts[0], aCounts[1]))

	b.WriteString("}\n\n")

	// emit any new helper funcs referenced by this test function
	s.emitAddrTakenHelpers(f, b, emit)
}

// complexityMeasure returns an integer that estimates how complex a
// given test function is relative to some other function. The more
// parameters + returns and the more complicated the types of the
// params/returns, the higher the number returned here. In theory this
// could be worked into the minimization process (e.g. pick the least
// complex func that reproduces the failure), but for now that isn't
// wired up yet.
func (f *funcdef) complexityMeasure() int {
	v := int(0)
	if f.isMethod {
		v += f.receiver.NumElements()
	}
	for _, p := range f.params {
		v += p.NumElements()
	}
	for _, r := range f.returns {
		v += r.NumElements()
	}
	return v
}

// emitRecursiveCall generates a recursive call to the test function in question.
func (s *genstate) emitRecursiveCall(f *funcdef) string {
	b := bytes.NewBuffer(nil)
	rcvr := ""
	if f.isMethod {
		rcvr = "rcvr."
	}
	b.WriteString(fmt.Sprintf(" %sTest%d(", rcvr, f.idx))
	for pi, p := range f.params {
		writeCom(b, pi)
		if p.IsControl() {
			b.WriteString(fmt.Sprintf(" %s-1", s.genParamRef(p, pi)))
		} else {
			if !p.IsBlank() {
				b.WriteString(fmt.Sprintf(" %s", s.genParamRef(p, pi)))
			} else {
				b.WriteString(fmt.Sprintf(" brc%d", pi))
			}
		}
	}
	b.WriteString(")")
	return b.String()
}

// emitReturn generates a return sequence.
func (s *genstate) emitReturn(f *funcdef, b *bytes.Buffer, doRecursiveCall bool) {
	// If any of the return values are address-taken, then instead of
	//
	//   return x, y, z
	//
	// we emit
	//
	//   r1 = ...
	//   r2 = ...
	//   ...
	//   return
	//
	// Make an initial pass through the returns to see if we need to do this.
	// Figure out the final return values in the process.
	indirectReturn := false
	retvals := []string{}
	for ri, r := range f.returns {
		if r.AddrTaken() != notAddrTaken {
			indirectReturn = true
		}
		t := ""
		if doRecursiveCall {
			t = "t"
		}
		retvals = append(retvals, fmt.Sprintf("rc%s%d", t, ri))
	}

	// generate the recursive call itself if applicable
	if doRecursiveCall {
		b.WriteString("  // recursive call\n  ")
		if s.ForceStackGrowth {
			b.WriteString("  hackStack() // force stack growth on next call\n")
		}
		rcall := s.emitRecursiveCall(f)
		if indirectReturn {
			for ri := range f.returns {
				writeCom(b, ri)
				b.WriteString(fmt.Sprintf("  rct%d", ri))
			}
			b.WriteString(" := ")
			b.WriteString(rcall)
			b.WriteString("\n")
		} else {
			if len(f.returns) == 0 {
				b.WriteString(fmt.Sprintf("%s\n  return\n", rcall))
			} else {
				b.WriteString(fmt.Sprintf("  return %s\n", rcall))
			}
			return
		}
	}

	// now the actual return
	if indirectReturn {
		for ri, r := range f.returns {
			s.genReturnAssign(b, r, ri, retvals[ri])
		}
		b.WriteString("  return\n")
	} else {
		b.WriteString("  return ")
		for ri := range f.returns {
			writeCom(b, ri)
			b.WriteString(retvals[ri])
		}
		b.WriteString("\n")
	}
}

func (s *genstate) GenPair(calloutfile *os.File, checkoutfile *os.File, fidx int, pidx int, b *bytes.Buffer, seed int64, emit bool) int64 {

	verb(1, "gen fidx %d pidx %d", fidx, pidx)

	checkTunables(tunables)
	s.tunables = tunables

	// Generate a function with a random number of params and returns
	s.wr = NewWrapRand(seed, s.RandCtl)
	s.wr.tag = "genfunc"
	fp := s.GenFunc(fidx, pidx)

	// Emit caller side
	wrcaller := NewWrapRand(seed, s.RandCtl)
	s.wr = wrcaller
	s.wr.tag = "caller"
	s.emitCaller(fp, b, pidx)
	if emit {
		b.WriteTo(calloutfile)
	}
	b.Reset()

	// Emit checker side
	wrchecker := NewWrapRand(seed, s.RandCtl)
	s.wr = wrchecker
	s.wr.tag = "checker"
	s.emitChecker(fp, b, pidx, emit)
	if emit {
		b.WriteTo(checkoutfile)
	}
	b.Reset()
	wrchecker.Check(wrcaller)

	return seed + 1
}

func (s *genstate) openOutputFile(filename string, pk string, imports []string, ipref string) *os.File {
	iprefix := func(f string) string {
		if ipref == "" {
			return f
		}
		return ipref + "/" + f
	}
	verb(1, "opening %s", filename)
	outf, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
	if err != nil {
		log.Fatal(err)
	}
	haveunsafe := false
	outf.WriteString(fmt.Sprintf("package %s\n\n", pk))
	for _, imp := range imports {
		if imp == "reflect" {
			outf.WriteString("import \"reflect\"\n")
			continue
		}
		if imp == "unsafe" {
			outf.WriteString("import _ \"unsafe\"\n")
			haveunsafe = true
			continue
		}
		if imp == s.utilsPkg() {

			outf.WriteString(fmt.Sprintf("import . \"%s\"\n", iprefix(imp)))
			continue
		}
		outf.WriteString(fmt.Sprintf("import \"%s\"\n", iprefix(imp)))
	}
	outf.WriteString("\n")
	if s.ForceStackGrowth && haveunsafe {
		outf.WriteString("// Hack: reach into runtime to grab this testing hook.\n")
		outf.WriteString("//go:linkname hackStack runtime.gcTestMoveStackOnNextCall\n")
		outf.WriteString("func hackStack()\n\n")
	}
	return outf
}

type miscVals struct {
	NumTpk   int
	MaxFail  int
	NumTests int
}

const utilsTemplate = `

import (
  "fmt"
  "os"
)

type UtilsType int
var ParamFailCount [{{.NumTpk}}]int
var ReturnFailCount [{{.NumTpk}}]int
var FailCount [{{.NumTpk}}]int
var Mode [{{.NumTpk}}]string

//go:noinline
func NoteFailure(cm int, pidx int, fidx int, pkg string, pref string, parmNo int, isret bool, _ uint64) {
	if isret {
		if ParamFailCount[pidx] != 0 {
			return
		}
		ReturnFailCount[pidx]++
	} else {
		ParamFailCount[pidx]++
	}
	fmt.Fprintf(os.Stderr, "Error: fail %s |%d|%d|%d| =%s.Test%d= %s %d\n", Mode, cm, pidx, fidx, pkg, fidx, pref, parmNo)

	if ParamFailCount[pidx]+FailCount[pidx]+ReturnFailCount[pidx] > {{.MaxFail}} {
		os.Exit(1)
	}
}

//go:noinline
func NoteFailureElem(cm int, pidx int, fidx int, pkg string, pref string, parmNo int, elem int, isret bool, _ uint64) {

	if isret {
		if ParamFailCount[pidx] != 0 {
			return
		}
		ReturnFailCount[pidx]++
	} else {
		ParamFailCount[pidx]++
	}
	fmt.Fprintf(os.Stderr, "Error: fail %s |%d|%d|%d| =%s.Test%d= %s %d elem %d\n", Mode, cm, pidx, fidx, pkg, fidx, pref, parmNo, elem)

	if ParamFailCount[pidx]+FailCount[pidx]+ReturnFailCount[pidx] > {{.MaxFail}} {
		os.Exit(1)
	}
}

func BeginFcn(p int) {
	ParamFailCount[p] = 0
	ReturnFailCount[p] = 0
}

func EndFcn(p int) {
	FailCount[p] += ParamFailCount[p]
	FailCount[p] += ReturnFailCount[p]
}
`

func (s *genstate) emitUtils(outf *os.File, maxfail int, numtpk int) {
	vals := miscVals{
		NumTpk:  numtpk,
		MaxFail: maxfail,
	}
	t := template.Must(template.New("utils").Parse(utilsTemplate))
	err := t.Execute(outf, vals)
	if err != nil {
		log.Fatal(err)
	}
}

const mainPreamble = `

import (
	"fmt"
	"os"
)

func main() {
  fmt.Fprintf(os.Stderr, "starting main\n")
`

func (s *genstate) emitMain(outf *os.File, numit int, fcnmask map[int]int, pkmask map[int]int) {
	fmt.Fprintf(outf, "%s", mainPreamble)
	fmt.Fprintf(outf, "  pch := make(chan bool, %d)\n", s.NumTestPackages)
	for k := 0; k < s.NumTestPackages; k++ {
		cp := fmt.Sprintf("%s%s%d", s.Tag, CallerName, k)
		fmt.Fprintf(outf, "  go func(ch chan bool) {\n")
		for i := range numit {
			if shouldEmitFP(i, k, fcnmask, pkmask) {
				fmt.Fprintf(outf, "    %s.%s%d(\"normal\")\n", cp, CallerName, i)
				if s.tunables.doReflectCall {
					fmt.Fprintf(outf, "    %s.%s%d(\"reflect\")\n", cp, CallerName, i)
				}
			}
		}
		fmt.Fprintf(outf, "    pch <- true\n")
		fmt.Fprintf(outf, "  }(pch)\n")
	}
	fmt.Fprintf(outf, "  for pidx := 0; pidx < %d; pidx++ {\n", s.NumTestPackages)
	fmt.Fprintf(outf, "    _ = <- pch\n")
	fmt.Fprintf(outf, "  }\n")
	fmt.Fprintf(outf, "  tf := 0\n")
	fmt.Fprintf(outf, "  for pidx := 0; pidx < %d; pidx++ {\n", s.NumTestPackages)
	fmt.Fprintf(outf, "    tf += FailCount[pidx]\n")
	fmt.Fprintf(outf, "  }\n")
	fmt.Fprintf(outf, "  if tf != 0 {\n")
	fmt.Fprintf(outf, "    fmt.Fprintf(os.Stderr, \"FAILURES: %%d\\n\", tf)\n")
	fmt.Fprintf(outf, "    os.Exit(2)\n")
	fmt.Fprintf(outf, "  }\n")
	fmt.Fprintf(outf, "  fmt.Fprintf(os.Stderr, \"finished %d tests\\n\")\n", numit*s.NumTestPackages)
	fmt.Fprintf(outf, "}\n")
}

func makeDir(d string) {
	fi, err := os.Stat(d)
	if err == nil && fi.IsDir() {
		return
	}
	verb(1, "creating %s", d)
	if err := os.Mkdir(d, 0777); err != nil {
		log.Fatal(err)
	}
}

func (s *genstate) callerPkg(which int) string {
	return s.Tag + CallerName + strconv.Itoa(which)
}

func (s *genstate) callerFile(which int) string {
	cp := s.callerPkg(which)
	return filepath.Join(s.OutDir, cp, cp+".go")
}

func (s *genstate) checkerPkg(which int) string {
	return s.Tag + CheckerName + strconv.Itoa(which)
}

func (s *genstate) checkerFile(which int) string {
	cp := s.checkerPkg(which)
	return filepath.Join(s.OutDir, cp, cp+".go")
}

func (s *genstate) utilsPkg() string {
	return s.Tag + "Utils"
}

func (s *genstate) beginPackage(pkidx int) {
	s.pkidx = pkidx
	s.derefFuncs = make(map[string]string)
	s.assignFuncs = make(map[string]string)
	s.allocFuncs = make(map[string]string)
	s.globVars = make(map[string]string)
	s.genvalFuncs = make(map[string]string)
}

func runImports(files []string) {
	verb(1, "... running goimports")
	args := make([]string, 0, len(files)+1)
	args = append(args, "-w")
	args = append(args, files...)
	cmd := exec.Command("goimports", args...)
	coutput, cerr := cmd.CombinedOutput()
	if cerr != nil {
		log.Fatalf("goimports command failed: %s", string(coutput))
	}
	verb(1, "... goimports run complete")
}

// shouldEmitFP returns true if we should actually emit code for the function
// with the specified package + fcn indices. For "regular" runs, fcnmask and pkmask
// will be empty, meaning we want to emit every function in every package. The
// fuzz-runner program also tries to do testcase "minimization", which means that it
// will try to whittle down the set of packages and functions (by running the generator
// using the fcnmask and pkmask options) to emit only specific packages or functions.
func shouldEmitFP(fn int, pk int, fcnmask map[int]int, pkmask map[int]int) bool {
	emitpk := true
	emitfn := true
	if len(pkmask) != 0 {
		emitpk = false
		if _, ok := pkmask[pk]; ok {
			emitpk = true
		}
	}
	if len(fcnmask) != 0 {
		emitfn = false
		if _, ok := fcnmask[fn]; ok {
			emitfn = true
		}
	}
	doemit := emitpk && emitfn
	verb(2, "shouldEmitFP(F=%d,P=%d) returns %v", fn, pk, doemit)
	return doemit
}

// Generate is the top level code generation hook for this package.
// Emits code according to the schema in config object 'c'.
func Generate(c GenConfig) int {
	mainpkg := c.Tag + "Main"

	var ipref string
	if len(c.PkgPath) > 0 {
		ipref = c.PkgPath
	}

	s := genstate{
		GenConfig: c,
		ipref:     ipref,
	}

	if s.OutDir != "." {
		verb(1, "creating %s", s.OutDir)
		makeDir(s.OutDir)
	}

	mainimports := []string{}
	for i := 0; i < s.NumTestPackages; i++ {
		if shouldEmitFP(-1, i, nil, s.PkgMask) {
			makeDir(s.OutDir + "/" + s.callerPkg(i))
			makeDir(s.OutDir + "/" + s.checkerPkg(i))
			makeDir(s.OutDir + "/" + s.utilsPkg())
			mainimports = append(mainimports, s.callerPkg(i))
		}
	}
	mainimports = append(mainimports, s.utilsPkg())

	// Emit utils package.
	verb(1, "emit utils")
	utilsfile := s.OutDir + "/" + s.utilsPkg() + "/" + s.utilsPkg() + ".go"
	utilsoutfile := s.openOutputFile(utilsfile, s.utilsPkg(), []string{}, "")
	s.emitUtils(utilsoutfile, s.MaxFail, s.NumTestPackages)
	utilsoutfile.Close()

	mainfile := s.OutDir + "/" + mainpkg + ".go"
	mainoutfile := s.openOutputFile(mainfile, "main", mainimports, ipref)

	allfiles := []string{mainfile, utilsfile}
	for k := 0; k < s.NumTestPackages; k++ {
		callerImports := []string{s.checkerPkg(k), s.utilsPkg()}
		checkerImports := []string{s.utilsPkg()}
		if tunables.doReflectCall {
			callerImports = append(callerImports, "reflect")
		}
		if s.ForceStackGrowth {
			callerImports = append(callerImports, "unsafe")
			checkerImports = append(checkerImports, "unsafe")
		}
		var calleroutfile, checkeroutfile *os.File
		if shouldEmitFP(-1, k, nil, s.PkgMask) {
			calleroutfile = s.openOutputFile(s.callerFile(k), s.callerPkg(k),
				callerImports, ipref)
			checkeroutfile = s.openOutputFile(s.checkerFile(k), s.checkerPkg(k),
				checkerImports, ipref)
			allfiles = append(allfiles, s.callerFile(k), s.checkerFile(k))
		}

		s.beginPackage(k)

		var b bytes.Buffer
		for i := 0; i < s.NumTestFunctions; i++ {
			doemit := shouldEmitFP(i, k, s.FcnMask, s.PkgMask)
			s.Seed = s.GenPair(calleroutfile, checkeroutfile, i, k,
				&b, s.Seed, doemit)
		}

		// When minimization is in effect, we sometimes wind
		// up eliminating all refs to the utils package. Add a
		// dummy to help with this.
		fmt.Fprintf(calleroutfile, "\n// dummy\nvar Dummy UtilsType\n")
		fmt.Fprintf(checkeroutfile, "\n// dummy\nvar Dummy UtilsType\n")
		calleroutfile.Close()
		checkeroutfile.Close()
	}
	s.emitMain(mainoutfile, s.NumTestFunctions, s.FcnMask, s.PkgMask)

	// emit go.mod
	verb(1, "opening go.mod")
	fn := s.OutDir + "/go.mod"
	outf, err := os.OpenFile(fn, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0666)
	if err != nil {
		log.Fatal(err)
	}
	outf.WriteString(fmt.Sprintf("module %s\n\ngo 1.17\n", s.PkgPath))
	outf.Close()

	verb(1, "closing files")
	mainoutfile.Close()

	if s.errs == 0 && s.RunGoImports {
		runImports(allfiles)
	}

	return s.errs
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/mapparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
)

// mapparm describes a parameter of map type; it implements the
// "parm" interface.
type mapparm struct {
	aname   string
	qname   string
	keytype parm
	valtype parm
	keytmp  string
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p mapparm) IsControl() bool {
	return false
}

func (p mapparm) TypeName() string {
	return p.aname
}

func (p mapparm) QualName() string {
	return p.qname
}

func (p mapparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	n := p.aname
	if caller {
		n = p.qname
	}
	b.WriteString(fmt.Sprintf("%s %s%s", prefix, n, suffix))
}

func (p mapparm) String() string {
	return fmt.Sprintf("%s map[%s]%s", p.aname,
		p.keytype.String(), p.valtype.String())
}

func (p mapparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	var buf bytes.Buffer

	verb(5, "mapparm.GenValue(%d)", value)

	n := p.aname
	if caller {
		n = p.qname
	}
	buf.WriteString(fmt.Sprintf("%s{", n))
	buf.WriteString(p.keytmp + ": ")

	var valstr string
	valstr, value = s.GenValue(f, p.valtype, value, caller)
	buf.WriteString(valstr + "}")
	return buf.String(), value
}

func (p mapparm) GenElemRef(elidx int, path string) (string, parm) {
	vne := p.valtype.NumElements()
	verb(4, "begin GenElemRef(%d,%s) on %s %d", elidx, path, p.String(), vne)

	ppath := fmt.Sprintf("%s[mkt.%s]", path, p.keytmp)

	// otherwise dig into the value
	verb(4, "recur GenElemRef(%d,...)", elidx)

	// Otherwise our victim is somewhere inside the value
	if p.IsBlank() {
		ppath = "_"
	}
	return p.valtype.GenElemRef(elidx, ppath)
}

func (p mapparm) NumElements() int {
	return p.valtype.NumElements()
}

func (p mapparm) HasPointer() bool {
	return true
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/numparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
	"math"
)

// numparm describes a numeric parameter type; it implements the
// "parm" interface.
type numparm struct {
	tag         string
	widthInBits uint32
	ctl         bool
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

var f32parm *numparm = &numparm{
	tag:         "float",
	widthInBits: uint32(32),
	ctl:         false,
}
var f64parm *numparm = &numparm{
	tag:         "float",
	widthInBits: uint32(64),
	ctl:         false,
}

func (p numparm) TypeName() string {
	if p.tag == "byte" {
		return "byte"
	}
	return fmt.Sprintf("%s%d", p.tag, p.widthInBits)
}

func (p numparm) QualName() string {
	return p.TypeName()
}

func (p numparm) String() string {
	if p.tag == "byte" {
		return "byte"
	}
	ctl := ""
	if p.ctl {
		ctl = " [ctl=yes]"
	}
	return fmt.Sprintf("%s%s", p.TypeName(), ctl)
}

func (p numparm) NumElements() int {
	return 1
}

func (p numparm) IsControl() bool {
	return p.ctl
}

func (p numparm) GenElemRef(elidx int, path string) (string, parm) {
	return path, &p
}

func (p numparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	t := fmt.Sprintf("%s%d%s", p.tag, p.widthInBits, suffix)
	if p.tag == "byte" {
		t = fmt.Sprintf("%s%s", p.tag, suffix)
	}
	b.WriteString(prefix + " " + t)
}

func (p numparm) genRandNum(s *genstate, value int) (string, int) {
	which := uint8(s.wr.Intn(int64(100)))
	if p.tag == "int" {
		var v int64
		if which < 3 {
			// max
			v = (1 << (p.widthInBits - 1)) - 1

		} else if which < 5 {
			// min
			v = (-1 << (p.widthInBits - 1))
		} else {
			nrange := int64(1 << (p.widthInBits - 2))
			v = s.wr.Intn(nrange)
			if value%2 != 0 {
				v = -v
			}
		}
		return fmt.Sprintf("%s%d(%d)", p.tag, p.widthInBits, v), value + 1
	}
	if p.tag == "uint" || p.tag == "byte" {
		nrange := int64(1 << (p.widthInBits - 2))
		v := s.wr.Intn(nrange)
		if p.tag == "byte" {
			return fmt.Sprintf("%s(%d)", p.tag, v), value + 1
		}
		return fmt.Sprintf("%s%d(0x%x)", p.tag, p.widthInBits, v), value + 1
	}
	if p.tag == "float" {
		if p.widthInBits == 32 {
			rf := s.wr.Float32() * (math.MaxFloat32 / 4)
			if value%2 != 0 {
				rf = -rf
			}
			return fmt.Sprintf("%s%d(%v)", p.tag, p.widthInBits, rf), value + 1
		}
		if p.widthInBits == 64 {
			return fmt.Sprintf("%s%d(%v)", p.tag, p.widthInBits,
				s.wr.NormFloat64()), value + 1
		}
		panic("unknown float type")
	}
	if p.tag == "complex" {
		if p.widthInBits == 64 {
			f1, v2 := f32parm.genRandNum(s, value)
			f2, v3 := f32parm.genRandNum(s, v2)
			return fmt.Sprintf("complex(%s,%s)", f1, f2), v3
		}
		if p.widthInBits == 128 {
			f1, v2 := f64parm.genRandNum(s, value)
			f2, v3 := f64parm.genRandNum(s, v2)
			return fmt.Sprintf("complex(%v,%v)", f1, f2), v3
		}
		panic("unknown complex type")
	}
	panic("unknown numeric type")
}

func (p numparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	r, nv := p.genRandNum(s, value)
	verb(5, "numparm.GenValue(%d) = %s", value, r)
	return r, nv
}

func (p numparm) HasPointer() bool {
	return false
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/parm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
	"os"
	"sort"
)

// parm is an interface describing an abstract parameter var or return
// var; there will be concrete types of various sorts that implement
// this interface.
type parm interface {

	// Declare emits text containing a declaration of this param
	// or return var into the specified buffer. Prefix is a tag to
	// prepend before the declaration (for example a variable
	// name) followed by a space; suffix is an arbitrary string to
	// tack onto the end of the param's type text. Here 'caller'
	// is set to true if we're emitting the caller part of a test
	// pair as opposed to the checker.
	Declare(b *bytes.Buffer, prefix string, suffix string, caller bool)

	// GenElemRef returns a pair [X,Y] corresponding to a
	// component piece of some composite parm, where X is a string
	// forming the reference (ex: ".field" if we're picking out a
	// struct field) and Y is a parm object corresponding to the
	// type of the element.
	GenElemRef(elidx int, path string) (string, parm)

	// GenValue constructs a new concrete random value appropriate
	// for the type in question and returns it, along with a
	// sequence number indicating how many random decisions we had
	// to make. Here "s" is the current generator state, "f" is
	// the current function we're emitting, value is a sequence
	// number indicating how many random decisions have been made
	// up until this point, and 'caller' is set to true if we're
	// emitting the caller part of a test pair as opposed to the
	// checker.  Return value is a pair [V,I] where V is the text
	// if the value, and I is a new sequence number reflecting any
	// additional random choices we had to make.  For example, if
	// the parm is something like "type Foo struct { f1 int32; f2
	// float64 }" then we might expect GenValue to emit something
	// like "Foo{int32(-9), float64(123.123)}".
	GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int)

	// IsControl returns true if this specific param has been marked
	// as the single param that controls recursion for a recursive
	// checker function. The test code doesn't check this param for a specific
	// value, but instead returns early if it has value 0 or decrements it
	// on a recursive call.
	IsControl() bool

	// NumElements returns the total number of discrete elements contained
	// in this parm. For non-composite types, this will always be 1.
	NumElements() int

	// String returns a descriptive string for this parm.
	String() string

	// TypeName returns the non-qualified type name for this parm.
	TypeName() string

	// QualName returns a package-qualified type name for this parm.
	QualName() string

	// HasPointer returns true if this parm is of pointer type, or
	// if it is a composite that has a pointer element somewhere inside.
	// Strings and slices return true for this hook.
	HasPointer() bool

	// IsBlank() returns true if the name of this parm is "_" (that is,
	// if we randomly chose to make it a blank). SetBlank() is used
	// to set the 'blank' property for this parm.
	IsBlank() bool
	SetBlank(v bool)

	// AddrTaken() return a token indicating whether this parm should
	// be address taken or not, the nature of the address-taken-ness (see
	// below at the def of addrTakenHow). SetAddrTaken is used to set
	// the address taken property of the parm.
	AddrTaken() addrTakenHow
	SetAddrTaken(val addrTakenHow)

	// IsGenVal() returns true if the values of this type should
	// be obtained by calling a helper func, as opposed to
	// emitting code inline (as one would for things like numeric
	// types). SetIsGenVal is used to set the gen-val property of
	// the parm.
	IsGenVal() bool
	SetIsGenVal(val bool)

	// SkipCompare() returns true if we've randomly decided that
	// we don't want to compare the value for this param or
	// return.  SetSkipCompare is used to set the skip-compare
	// property of the parm.
	SkipCompare() skipCompare
	SetSkipCompare(val skipCompare)
}

type addrTakenHow uint8

const (
	// Param not address taken.
	notAddrTaken addrTakenHow = 0

	// Param address is taken and used for simple reads/writes.
	addrTakenSimple addrTakenHow = 1

	// Param address is taken and passed to a well-behaved function.
	addrTakenPassed addrTakenHow = 2

	// Param address is taken and stored to a global var.
	addrTakenHeap addrTakenHow = 3
)

func (a *addrTakenHow) AddrTaken() addrTakenHow {
	return *a
}

func (a *addrTakenHow) SetAddrTaken(val addrTakenHow) {
	*a = val
}

type isBlank bool

func (b *isBlank) IsBlank() bool {
	return bool(*b)
}

func (b *isBlank) SetBlank(val bool) {
	*b = isBlank(val)
}

type isGenValFunc bool

func (g *isGenValFunc) IsGenVal() bool {
	return bool(*g)
}

func (g *isGenValFunc) SetIsGenVal(val bool) {
	*g = isGenValFunc(val)
}

type skipCompare int

const (
	// Param not address taken.
	SkipAll     = -1
	SkipNone    = 0
	SkipPayload = 1
)

func (s *skipCompare) SkipCompare() skipCompare {
	return skipCompare(*s)
}

func (s *skipCompare) SetSkipCompare(val skipCompare) {
	*s = skipCompare(val)
}

// containedParms takes an arbitrary param 'p' and returns a slice
// with 'p' itself plus any component parms contained within 'p'.
func containedParms(p parm) []parm {
	visited := make(map[string]parm)
	worklist := []parm{p}

	addToWork := func(p parm) {
		if p == nil {
			panic("not expected")
		}
		if _, ok := visited[p.TypeName()]; !ok {
			worklist = append(worklist, p)
		}
	}

	for len(worklist) != 0 {
		cp := worklist[0]
		worklist = worklist[1:]
		if _, ok := visited[cp.TypeName()]; ok {
			continue
		}
		visited[cp.TypeName()] = cp
		switch x := cp.(type) {
		case *mapparm:
			addToWork(x.keytype)
			addToWork(x.valtype)
		case *structparm:
			for _, fld := range x.fields {
				addToWork(fld)
			}
		case *arrayparm:
			addToWork(x.eltype)
		case *pointerparm:
			addToWork(x.totype)
		case *typedefparm:
			addToWork(x.target)
		}
	}
	rv := []parm{}
	for _, v := range visited {
		rv = append(rv, v)
	}
	sort.Slice(rv, func(i, j int) bool {
		if rv[i].TypeName() == rv[j].TypeName() {
			fmt.Fprintf(os.Stderr, "%d %d %+v %+v %s %s\n", i, j, rv[i], rv[i].String(), rv[j], rv[j].String())
			panic("unexpected")
		}
		return rv[i].TypeName() < rv[j].TypeName()
	})
	return rv
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/pointerparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
)

// pointerparm describes a parameter of pointer type; it implements the
// "parm" interface.
type pointerparm struct {
	tag    string
	totype parm
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p pointerparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	n := p.totype.TypeName()
	if caller {
		n = p.totype.QualName()
	}
	b.WriteString(fmt.Sprintf("%s *%s%s", prefix, n, suffix))
}

func (p pointerparm) GenElemRef(elidx int, path string) (string, parm) {
	return path, &p
}

func (p pointerparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	pref := ""
	if caller {
		pref = s.checkerPkg(s.pkidx) + "."
	}
	var valstr string
	valstr, value = s.GenValue(f, p.totype, value, caller)
	fname := s.genAllocFunc(p.totype)
	return fmt.Sprintf("%s%s(%s)", pref, fname, valstr), value
}

func (p pointerparm) IsControl() bool {
	return false
}

func (p pointerparm) NumElements() int {
	return 1
}

func (p pointerparm) String() string {
	return fmt.Sprintf("*%s", p.totype)
}

func (p pointerparm) TypeName() string {
	return fmt.Sprintf("*%s", p.totype.TypeName())
}

func (p pointerparm) QualName() string {
	return fmt.Sprintf("*%s", p.totype.QualName())
}

func mkPointerParm(to parm) pointerparm {
	var pp pointerparm
	pp.tag = "pointer"
	pp.totype = to
	return pp
}

func (p pointerparm) HasPointer() bool {
	return true
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/stringparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
)

// stringparm describes a parameter of string type; it implements the
// "parm" interface
type stringparm struct {
	tag string
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p stringparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	b.WriteString(prefix + " string" + suffix)
}

func (p stringparm) GenElemRef(elidx int, path string) (string, parm) {
	return path, &p
}

var letters = []rune("�꿦3򂨃f6ꂅ8ˋ<􂊇񊶿(z̽|ϣᇊ񁗇򟄼q񧲥筁{ЂƜĽ")

func (p stringparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	ns := len(letters) - 9
	nel := int(s.wr.Intn(8))
	st := int(s.wr.Intn(int64(ns)))
	en := min(st+nel, ns)
	return "\"" + string(letters[st:en]) + "\"", value + 1
}

func (p stringparm) IsControl() bool {
	return false
}

func (p stringparm) NumElements() int {
	return 1
}

func (p stringparm) String() string {
	return "string"
}

func (p stringparm) TypeName() string {
	return "string"
}

func (p stringparm) QualName() string {
	return "string"
}

func (p stringparm) HasPointer() bool {
	return false
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/structparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
	"strings"
)

// structparm describes a parameter of struct type; it implements the
// "parm" interface.
type structparm struct {
	sname  string
	qname  string
	fields []parm
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p structparm) TypeName() string {
	return p.sname
}

func (p structparm) QualName() string {
	return p.qname
}

func (p structparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	n := p.sname
	if caller {
		n = p.qname
	}
	b.WriteString(fmt.Sprintf("%s %s%s", prefix, n, suffix))
}

func (p structparm) FieldName(i int) string {
	if p.fields[i].IsBlank() {
		return "_"
	}
	return fmt.Sprintf("F%d", i)
}

func (p structparm) String() string {
	var buf bytes.Buffer

	buf.WriteString(fmt.Sprintf("struct %s {\n", p.sname))
	for fi, f := range p.fields {
		buf.WriteString(fmt.Sprintf("%s %s\n", p.FieldName(fi), f.String()))
	}
	buf.WriteString("}")
	return buf.String()
}

func (p structparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	var buf bytes.Buffer

	verb(5, "structparm.GenValue(%d)", value)

	n := p.sname
	if caller {
		n = p.qname
	}
	buf.WriteString(fmt.Sprintf("%s{", n))
	nbfi := 0
	for fi, fld := range p.fields {
		var valstr string
		valstr, value = s.GenValue(f, fld, value, caller)
		if p.fields[fi].IsBlank() {
			buf.WriteString("/* ")
			valstr = strings.ReplaceAll(valstr, "/*", "[[")
			valstr = strings.ReplaceAll(valstr, "*/", "]]")
		} else {
			writeCom(&buf, nbfi)
		}
		buf.WriteString(p.FieldName(fi) + ": ")
		buf.WriteString(valstr)
		if p.fields[fi].IsBlank() {
			buf.WriteString(" */")
		} else {
			nbfi++
		}
	}
	buf.WriteString("}")
	return buf.String(), value
}

func (p structparm) IsControl() bool {
	return false
}

func (p structparm) NumElements() int {
	ne := 0
	for _, f := range p.fields {
		ne += f.NumElements()
	}
	return ne
}

func (p structparm) GenElemRef(elidx int, path string) (string, parm) {
	ct := 0
	verb(4, "begin GenElemRef(%d,%s) on %s", elidx, path, p.String())

	for fi, f := range p.fields {
		fne := f.NumElements()

		//verb(4, "+ examining field %d fne %d ct %d", fi, fne, ct)

		// Empty field. Continue on.
		if elidx == ct && fne == 0 {
			continue
		}

		// Is this field the element we're interested in?
		if fne == 1 && elidx == ct {

			// The field in question may be a composite that has only
			// multiple elements but a single non-zero-sized element.
			// If this is the case, keep going.
			if sp, ok := f.(*structparm); ok {
				if len(sp.fields) > 1 {
					ppath := fmt.Sprintf("%s.F%d", path, fi)
					if p.fields[fi].IsBlank() || path == "_" {
						ppath = "_"
					}
					return f.GenElemRef(elidx-ct, ppath)
				}
			}

			verb(4, "found field %d type %s in GenElemRef(%d,%s)", fi, f.TypeName(), elidx, path)
			ppath := fmt.Sprintf("%s.F%d", path, fi)
			if p.fields[fi].IsBlank() || path == "_" {
				ppath = "_"
			}
			return ppath, f
		}

		// Is the element we want somewhere inside this field?
		if fne > 1 && elidx >= ct && elidx < ct+fne {
			ppath := fmt.Sprintf("%s.F%d", path, fi)
			if p.fields[fi].IsBlank() || path == "_" {
				ppath = "_"
			}
			return f.GenElemRef(elidx-ct, ppath)
		}

		ct += fne
	}
	panic(fmt.Sprintf("GenElemRef failed for struct %s elidx %d", p.TypeName(), elidx))
}

func (p structparm) HasPointer() bool {
	for _, f := range p.fields {
		if f.HasPointer() {
			return true
		}
	}
	return false
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/typedefparm.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"bytes"
	"fmt"
)

// typedefparm describes a parameter that is a typedef of some other
// type; it implements the "parm" interface
type typedefparm struct {
	aname  string
	qname  string
	target parm
	isBlank
	addrTakenHow
	isGenValFunc
	skipCompare
}

func (p typedefparm) Declare(b *bytes.Buffer, prefix string, suffix string, caller bool) {
	n := p.aname
	if caller {
		n = p.qname
	}
	b.WriteString(fmt.Sprintf("%s %s%s", prefix, n, suffix))
}

func (p typedefparm) GenElemRef(elidx int, path string) (string, parm) {
	_, isarr := p.target.(*arrayparm)
	_, isstruct := p.target.(*structparm)
	_, ismap := p.target.(*mapparm)
	rv, rp := p.target.GenElemRef(elidx, path)
	// this is hacky, but I don't see a nicer way to do this
	if isarr || isstruct || ismap {
		return rv, rp
	}
	rp = &p
	return rv, rp
}

func (p typedefparm) GenValue(s *genstate, f *funcdef, value int, caller bool) (string, int) {
	n := p.aname
	if caller {
		n = p.qname
	}
	rv, v := s.GenValue(f, p.target, value, caller)
	rv = n + "(" + rv + ")"
	return rv, v
}

func (p typedefparm) IsControl() bool {
	return false
}

func (p typedefparm) NumElements() int {
	return p.target.NumElements()
}

func (p typedefparm) String() string {
	return fmt.Sprintf("%s typedef of %s", p.aname, p.target.String())

}

func (p typedefparm) TypeName() string {
	return p.aname

}

func (p typedefparm) QualName() string {
	return p.qname
}

func (p typedefparm) HasPointer() bool {
	return p.target.HasPointer()
}

func (s *genstate) makeTypedefParm(f *funcdef, target parm, pidx int) parm {
	var tdp typedefparm
	ns := len(f.typedefs)
	tdp.aname = fmt.Sprintf("MyTypeF%dS%d", f.idx, ns)
	tdp.qname = fmt.Sprintf("%s.MyTypeF%dS%d", s.checkerPkg(pidx), f.idx, ns)
	tdp.target = target
	tdp.SetBlank(uint8(s.wr.Intn(100)) < tunables.blankPerc)
	f.typedefs = append(f.typedefs, tdp)
	return &tdp
}


================================================
FILE: cmd/signature-fuzzer/internal/fuzz-generator/wraprand.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package generator

import (
	"fmt"
	"math/rand/v2"
	"os"
	"runtime"
	"strings"
)

const (
	RandCtlNochecks = 0
	RandCtlChecks   = 1 << iota
	RandCtlCapture
	RandCtlPanic
)

func NewWrapRand(seed int64, ctl int) *wraprand {
	return &wraprand{seed: seed, ctl: ctl, rand: rand.New(rand.NewPCG(0, uint64(seed)))}
}

type wraprand struct {
	f32calls  int
	f64calls  int
	intncalls int
	seed      int64
	tag       string
	calls     []string
	ctl       int
	rand      *rand.Rand
}

func (w *wraprand) captureCall(tag string, val string) {
	var call strings.Builder
	fmt.Fprintf(&call, "%s: %s\n", tag, val)
	pc := make([]uintptr, 10)
	n := runtime.Callers(1, pc)
	if n == 0 {
		panic("why?")
	}
	pc = pc[:n] // pass only valid pcs to runtime.CallersFrames
	frames := runtime.CallersFrames(pc)
	for {
		frame, more := frames.Next()
		if strings.Contains(frame.File, "testing.") {
			break
		}
		fmt.Fprintf(&call, "%s %s:%d\n", frame.Function, frame.File, frame.Line)
		if !more {
			break
		}

	}
	w.calls = append(w.calls, call.String())
}

func (w *wraprand) Intn(n int64) int64 {
	w.intncalls++
	rv := w.rand.Int64N(n)
	if w.ctl&RandCtlCapture != 0 {
		w.captureCall("Intn", fmt.Sprintf("%d", rv))
	}
	return rv
}

func (w *wraprand) Float32() float32 {
	w.f32calls++
	rv := w.rand.Float32()
	if w.ctl&RandCtlCapture != 0 {
		w.captureCall("Float32", fmt.Sprintf("%f", rv))
	}
	return rv
}

func (w *wraprand) NormFloat64() float64 {
	w.f64calls++
	rv := w.rand.NormFloat64()
	if w.ctl&RandCtlCapture != 0 {
		w.captureCall("NormFloat64", fmt.Sprintf("%f", rv))
	}
	return rv
}

func (w *wraprand) emitCalls(fn string) {
	outf, err := os.OpenFile(fn, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0o666)
	if err != nil {
		panic(err)
	}
	for _, c := range w.calls {
		fmt.Fprint(outf, c)
	}
	outf.Close()
}

func (w *wraprand) Equal(w2 *wraprand) bool {
	return w.f32calls == w2.f32calls &&
		w.f64calls == w2.f64calls &&
		w.intncalls == w2.intncalls
}

func (w *wraprand) Check(w2 *wraprand) {
	if w.ctl != 0 && !w.Equal(w2) {
		fmt.Fprintf(os.Stderr, "wraprand consistency check failed:\n")
		t := "w"
		if w.tag != "" {
			t = w.tag
		}
		t2 := "w2"
		if w2.tag != "" {
			t2 = w2.tag
		}
		fmt.Fprintf(os.Stderr, " %s: {f32:%d f64:%d i:%d}\n", t,
			w.f32calls, w.f64calls, w.intncalls)
		fmt.Fprintf(os.Stderr, " %s: {f32:%d f64:%d i:%d}\n", t2,
			w2.f32calls, w2.f64calls, w2.intncalls)
		if w.ctl&RandCtlCapture != 0 {
			f := fmt.Sprintf("/tmp/%s.txt", t)
			f2 := fmt.Sprintf("/tmp/%s.txt", t2)
			w.emitCalls(f)
			w2.emitCalls(f2)
			fmt.Fprintf(os.Stderr, "=-= emitted calls to %s, %s\n", f, f2)
		}
		if w.ctl&RandCtlPanic != 0 {
			panic("bad")
		}
	}
}

func (w *wraprand) Checkpoint(tag string) {
	if w.ctl&RandCtlCapture != 0 {
		w.calls = append(w.calls, "=-=\n"+tag+"\n=-=\n")
	}
}


================================================
FILE: cmd/splitdwarf/internal/macho/fat.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package macho

import (
	"encoding/binary"
	"io"
	"os"
)

// A FatFile is a Mach-O universal binary that contains at least one architecture.
type FatFile struct {
	Magic  uint32
	Arches []FatArch
	closer io.Closer
}

// A FatArchHeader represents a fat header for a specific image architecture.
type FatArchHeader struct {
	Cpu    Cpu
	SubCpu uint32
	Offset uint32
	Size   uint32
	Align  uint32
}

const fatArchHeaderSize = 5 * 4

// A FatArch is a Mach-O File inside a FatFile.
type FatArch struct {
	FatArchHeader
	*File
}

// NewFatFile creates a new FatFile for accessing all the Mach-O images in a
// universal binary. The Mach-O binary is expected to start at position 0 in
// the ReaderAt.
func NewFatFile(r io.ReaderAt) (*FatFile, error) {
	var ff FatFile
	sr := io.NewSectionReader(r, 0, 1<<63-1)

	// Read the fat_header struct, which is always in big endian.
	// Start with the magic number.
	err := binary.Read(sr, binary.BigEndian, &ff.Magic)
	if err != nil {
		return nil, formatError(0, "error reading magic number, %v", err)
	} else if ff.Magic != MagicFat {
		// See if this is a Mach-O file via its magic number. The magic
		// must be converted to little endian first though.
		var buf [4]byte
		binary.BigEndian.PutUint32(buf[:], ff.Magic)
		leMagic := binary.LittleEndian.Uint32(buf[:])
		if leMagic == Magic32 || leMagic == Magic64 {
			return nil, formatError(0, "not a fat Mach-O file, leMagic=0x%x", leMagic)
		} else {
			return nil, formatError(0, "invalid magic number, leMagic=0x%x", leMagic)
		}
	}
	offset := int64(4)

	// Read the number of FatArchHeaders that come after the fat_header.
	var narch uint32
	err = binary.Read(sr, binary.BigEndian, &narch)
	if err != nil {
		return nil, formatError(offset, "invalid fat_header %v", err)
	}
	offset += 4

	if narch < 1 {
		return nil, formatError(offset, "file contains no images, narch=%d", narch)
	}

	// Combine the Cpu and SubCpu (both uint32) into a uint64 to make sure
	// there are not duplicate architectures.
	seenArches := make(map[uint64]bool, narch)
	// Make sure that all images are for the same MH_ type.
	var machoType HdrType

	// Following the fat_header comes narch fat_arch structs that index
	// Mach-O images further in the file.
	ff.Arches = make([]FatArch, narch)
	for i := uint32(0); i < narch; i++ {
		fa := &ff.Arches[i]
		err = binary.Read(sr, binary.BigEndian, &fa.FatArchHeader)
		if err != nil {
			return nil, formatError(offset, "invalid fat_arch header, %v", err)
		}
		offset += fatArchHeaderSize

		fr := io.NewSectionReader(r, int64(fa.Offset), int64(fa.Size))
		fa.File, err = NewFile(fr)
		if err != nil {
			return nil, err
		}

		// Make sure the architecture for this image is not duplicate.
		seenArch := (uint64(fa.Cpu) << 32) | uint64(fa.SubCpu)
		if o, k := seenArches[seenArch]; o || k {
			return nil, formatError(offset, "duplicate architecture cpu=%v, subcpu=%#x", fa.Cpu, fa.SubCpu)
		}
		seenArches[seenArch] = true

		// Make sure the Mach-O type matches that of the first image.
		if i == 0 {
			machoType = HdrType(fa.Type)
		} else {
			if HdrType(fa.Type) != machoType {
				return nil, formatError(offset, "Mach-O type for architecture #%d (type=%#x) does not match first (type=%#x)", i, fa.Type, machoType)
			}
		}
	}

	return &ff, nil
}

// OpenFat opens the named file using os.Open and prepares it for use as a Mach-O
// universal binary.
func OpenFat(name string) (*FatFile, error) {
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	ff, err := NewFatFile(f)
	if err != nil {
		f.Close()
		return nil, err
	}
	ff.closer = f
	return ff, nil
}

func (ff *FatFile) Close() error {
	var err error
	if ff.closer != nil {
		err = ff.closer.Close()
		ff.closer = nil
	}
	return err
}


================================================
FILE: cmd/splitdwarf/internal/macho/file.go
================================================
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package macho implements access to Mach-O object files.
package macho

// High level access to low level data structures.

import (
	"bytes"
	"compress/zlib"
	"debug/dwarf"
	"encoding/binary"
	"fmt"
	"io"
	"os"
	"slices"
	"strings"
	"unsafe"
)

// A File represents an open Mach-O file.
type File struct {
	FileTOC

	Symtab   *Symtab
	Dysymtab *Dysymtab

	closer io.Closer
}

type FileTOC struct {
	FileHeader
	ByteOrder binary.ByteOrder
	Loads     []Load
	Sections  []*Section
}

func (t *FileTOC) AddLoad(l Load) {
	t.Loads = append(t.Loads, l)
	t.NCommands++
	t.SizeCommands += l.LoadSize(t)
}

// AddSegment adds segment s to the file table of contents,
// and also zeroes out the segment information with the expectation
// that this will be added next.
func (t *FileTOC) AddSegment(s *Segment) {
	t.AddLoad(s)
	s.Nsect = 0
	s.Firstsect = 0
}

// Adds section to the most recently added Segment
func (t *FileTOC) AddSection(s *Section) {
	g := t.Loads[len(t.Loads)-1].(*Segment)
	if g.Nsect == 0 {
		g.Firstsect = uint32(len(t.Sections))
	}
	g.Nsect++
	t.Sections = append(t.Sections, s)
	sectionsize := uint32(unsafe.Sizeof(Section32{}))
	if g.Command() == LcSegment64 {
		sectionsize = uint32(unsafe.Sizeof(Section64{}))
	}
	t.SizeCommands += sectionsize
	g.Len += sectionsize
}

// A Load represents any Mach-O load command.
type Load interface {
	String() string
	Command() LoadCmd
	LoadSize(*FileTOC) uint32 // Need the TOC for alignment, sigh.
	Put([]byte, binary.ByteOrder) int

	// command LC_DYLD_INFO_ONLY contains offsets into __LINKEDIT
	// e.g., from "otool -l a.out"
	//
	// 	Load command 3
	//       cmd LC_SEGMENT_64
	//   cmdsize 72
	//   segname __LINKEDIT
	//    vmaddr 0x0000000100002000
	//    vmsize 0x0000000000001000
	//   fileoff 8192
	//  filesize 520
	//   maxprot 0x00000007
	//  initprot 0x00000001
	//    nsects 0
	//     flags 0x0
	// Load command 4
	//             cmd LC_DYLD_INFO_ONLY
	//         cmdsize 48
	//      rebase_off 8192
	//     rebase_size 8
	//        bind_off 8200
	//       bind_size 24
	//   weak_bind_off 0
	//  weak_bind_size 0
	//   lazy_bind_off 8224
	//  lazy_bind_size 16
	//      export_off 8240
	//     export_size 48
}

// LoadBytes is the uninterpreted bytes of a Mach-O load command.
type LoadBytes []byte

// A SegmentHeader is the header for a Mach-O 32-bit or 64-bit load segment command.
type SegmentHeader struct {
	LoadCmd
	Len       uint32
	Name      string // 16 characters or fewer
	Addr      uint64 // memory address
	Memsz     uint64 // memory size
	Offset    uint64 // file offset
	Filesz    uint64 // number of bytes starting at that file offset
	Maxprot   uint32
	Prot      uint32
	Nsect     uint32
	Flag      SegFlags
	Firstsect uint32
}

// A Segment represents a Mach-O 32-bit or 64-bit load segment command.
type Segment struct {
	SegmentHeader

	// Embed ReaderAt for ReadAt method.
	// Do not embed SectionReader directly
	// to avoid having Read and Seek.
	// If a client wants Read and Seek it must use
	// Open() to avoid fighting over the seek offset
	// with other clients.
	io.ReaderAt
	sr *io.SectionReader
}

func (s *Segment) Put32(b []byte, o binary.ByteOrder) int {
	o.PutUint32(b[0*4:], uint32(s.LoadCmd))
	o.PutUint32(b[1*4:], s.Len)
	putAtMost16Bytes(b[2*4:], s.Name)
	o.PutUint32(b[6*4:], uint32(s.Addr))
	o.PutUint32(b[7*4:], uint32(s.Memsz))
	o.PutUint32(b[8*4:], uint32(s.Offset))
	o.PutUint32(b[9*4:], uint32(s.Filesz))
	o.PutUint32(b[10*4:], s.Maxprot)
	o.PutUint32(b[11*4:], s.Prot)
	o.PutUint32(b[12*4:], s.Nsect)
	o.PutUint32(b[13*4:], uint32(s.Flag))
	return 14 * 4
}

func (s *Segment) Put64(b []byte, o binary.ByteOrder) int {
	o.PutUint32(b[0*4:], uint32(s.LoadCmd))
	o.PutUint32(b[1*4:], s.Len)
	putAtMost16Bytes(b[2*4:], s.Name)
	o.PutUint64(b[6*4+0*8:], s.Addr)
	o.PutUint64(b[6*4+1*8:], s.Memsz)
	o.PutUint64(b[6*4+2*8:], s.Offset)
	o.PutUint64(b[6*4+3*8:], s.Filesz)
	o.PutUint32(b[6*4+4*8:], s.Maxprot)
	o.PutUint32(b[7*4+4*8:], s.Prot)
	o.PutUint32(b[8*4+4*8:], s.Nsect)
	o.PutUint32(b[9*4+4*8:], uint32(s.Flag))
	return 10*4 + 4*8
}

// LoadCmdBytes is a command-tagged sequence of bytes.
// This is used for Load Commands that are not (yet)
// interesting to us, and to common up this behavior for
// all those that are.
type LoadCmdBytes struct {
	LoadCmd
	LoadBytes
}

type SectionHeader struct {
	Name      string
	Seg       string
	Addr      uint64
	Size      uint64
	Offset    uint32
	Align     uint32
	Reloff    uint32
	Nreloc    uint32
	Flags     SecFlags
	Reserved1 uint32
	Reserved2 uint32
	Reserved3 uint32 // only present if original was 64-bit
}

// A Reloc represents a Mach-O relocation.
type Reloc struct {
	Addr  uint32
	Value uint32
	// when Scattered == false && Extern == true, Value is the symbol number.
	// when Scattered == false && Extern == false, Value is the section number.
	// when Scattered == true, Value is the value that this reloc refers to.
	Type      uint8
	Len       uint8 // 0=byte, 1=word, 2=long, 3=quad
	Pcrel     bool
	Extern    bool // valid if Scattered == false
	Scattered bool
}

type Section struct {
	SectionHeader
	Relocs []Reloc

	// Embed ReaderAt for ReadAt method.
	// Do not embed SectionReader directly
	// to avoid having Read and Seek.
	// If a client wants Read and Seek it must use
	// Open() to avoid fighting over the seek offset
	// with other clients.
	io.ReaderAt
	sr *io.SectionReader
}

func (s *Section) Put32(b []byte, o binary.ByteOrder) int {
	putAtMost16Bytes(b[0:], s.Name)
	putAtMost16Bytes(b[16:], s.Seg)
	o.PutUint32(b[8*4:], uint32(s.Addr))
	o.PutUint32(b[9*4:], uint32(s.Size))
	o.PutUint32(b[10*4:], s.Offset)
	o.PutUint32(b[11*4:], s.Align)
	o.PutUint32(b[12*4:], s.Reloff)
	o.PutUint32(b[13*4:], s.Nreloc)
	o.PutUint32(b[14*4:], uint32(s.Flags))
	o.PutUint32(b[15*4:], s.Reserved1)
	o.PutUint32(b[16*4:], s.Reserved2)
	a := 17 * 4
	return a + s.PutRelocs(b[a:], o)
}

func (s *Section) Put64(b []byte, o binary.ByteOrder) int {
	putAtMost16Bytes(b[0:], s.Name)
	putAtMost16Bytes(b[16:], s.Seg)
	o.PutUint64(b[8*4+0*8:], s.Addr)
	o.PutUint64(b[8*4+1*8:], s.Size)
	o.PutUint32(b[8*4+2*8:], s.Offset)
	o.PutUint32(b[9*4+2*8:], s.Align)
	o.PutUint32(b[10*4+2*8:], s.Reloff)
	o.PutUint32(b[11*4+2*8:], s.Nreloc)
	o.PutUint32(b[12*4+2*8:], uint32(s.Flags))
	o.PutUint32(b[13*4+2*8:], s.Reserved1)
	o.PutUint32(b[14*4+2*8:], s.Reserved2)
	o.PutUint32(b[15*4+2*8:], s.Reserved3)
	a := 16*4 + 2*8
	return a + s.PutRelocs(b[a:], o)
}

func (s *Section) PutRelocs(b []byte, o binary.ByteOrder) int {
	a := 0
	for _, r := range s.Relocs {
		var ri relocInfo
		typ := uint32(r.Type) & (1<<4 - 1)
		len := uint32(r.Len) & (1<<2 - 1)
		pcrel := uint32(0)
		if r.Pcrel {
			pcrel = 1
		}
		ext := uint32(0)
		if r.Extern {
			ext = 1
		}
		switch {
		case r.Scattered:
			ri.Addr = r.Addr&(1<<24-1) | typ<<24 | len<<28 | 1<<31 | pcrel<<30
			ri.Symnum = r.Value
		case o == binary.LittleEndian:
			ri.Addr = r.Addr
			ri.Symnum = r.Value&(1<<24-1) | pcrel<<24 | len<<25 | ext<<27 | typ<<28
		case o == binary.BigEndian:
			ri.Addr = r.Addr
			ri.Symnum = r.Value<<8 | pcrel<<7 | len<<5 | ext<<4 | typ
		}
		o.PutUint32(b, ri.Addr)
		o.PutUint32(b[4:], ri.Symnum)
		a += 8
		b = b[8:]
	}
	return a
}

func putAtMost16Bytes(b []byte, n string) {
	for i := range n { // at most 16 bytes
		if i == 16 {
			break
		}
		b[i] = n[i]
	}
}

// A Symbol is a Mach-O 32-bit or 64-bit symbol table entry.
type Symbol struct {
	Name  string
	Type  uint8
	Sect  uint8
	Desc  uint16
	Value uint64
}

/*
 * Mach-O reader
 */

// FormatError is returned by some operations if the data does
// not have the correct format for an object file.
type FormatError struct {
	off int64
	msg string
}

func formatError(off int64, format string, data ...any) *FormatError {
	return &FormatError{off, fmt.Sprintf(format, data...)}
}

func (e *FormatError) Error() string {
	return e.msg + fmt.Sprintf(" in record at byte %#x", e.off)
}

func (e *FormatError) String() string {
	return e.Error()
}

// DerivedCopy returns a modified copy of the TOC, with empty loads and sections,
// and with the specified header type and flags.
func (t *FileTOC) DerivedCopy(Type HdrType, Flags HdrFlags) *FileTOC {
	h := t.FileHeader
	h.NCommands, h.SizeCommands, h.Type, h.Flags = 0, 0, Type, Flags

	return &FileTOC{FileHeader: h, ByteOrder: t.ByteOrder}
}

// TOCSize returns the size in bytes of the object file representation
// of the header and Load Commands (including Segments and Sections, but
// not their contents) at the beginning of a Mach-O file.  This typically
// overlaps the text segment in the object file.
func (t *FileTOC) TOCSize() uint32 {
	return t.HdrSize() + t.LoadSize()
}

// LoadAlign returns the required alignment of Load commands in a binary.
// This is used to add padding for necessary alignment.
func (t *FileTOC) LoadAlign() uint64 {
	if t.Magic == Magic64 {
		return 8
	}
	return 4
}

// SymbolSize returns the size in bytes of a Symbol (Nlist32 or Nlist64)
func (t *FileTOC) SymbolSize() uint32 {
	if t.Magic == Magic64 {
		return uint32(unsafe.Sizeof(Nlist64{}))
	}
	return uint32(unsafe.Sizeof(Nlist32{}))
}

// HdrSize returns the size in bytes of the Macho header for a given
// magic number (where the magic number has been appropriately byte-swapped).
func (t *FileTOC) HdrSize() uint32 {
	switch t.Magic {
	case Magic32:
		return fileHeaderSize32
	case Magic64:
		return fileHeaderSize64
	case MagicFat:
		panic("MagicFat not handled yet")
	default:
		panic(fmt.Sprintf("Unexpected magic number 0x%x, expected Mach-O object file", t.Magic))
	}
}

// LoadSize returns the size of all the load commands in a file's table-of contents
// (but not their associated data, e.g., sections and symbol tables)
func (t *FileTOC) LoadSize() uint32 {
	cmdsz := uint32(0)
	for _, l := range t.Loads {
		s := l.LoadSize(t)
		cmdsz += s
	}
	return cmdsz
}

// FileSize returns the size in bytes of the header, load commands, and the
// in-file contents of all the segments and sections included in those
// load commands, accounting for their offsets within the file.
func (t *FileTOC) FileSize() uint64 {
	sz := uint64(t.LoadSize()) // ought to be contained in text segment, but just in case.
	for _, l := range t.Loads {
		if s, ok := l.(*Segment); ok {
			if m := s.Offset + s.Filesz; m > sz {
				sz = m
			}
		}
	}
	return sz
}

// Put writes the header and all load commands to buffer, using
// the byte ordering specified in FileTOC t.  For sections, this
// writes the headers that come in-line with the segment Load commands,
// but does not write the reference data for those sections.
func (t *FileTOC) Put(buffer []byte) int {
	next := t.FileHeader.Put(buffer, t.ByteOrder)
	for _, l := range t.Loads {
		if s, ok := l.(*Segment); ok {
			switch t.Magic {
			case Magic64:
				next += s.Put64(buffer[next:], t.ByteOrder)
				for i := uint32(0); i < s.Nsect; i++ {
					c := t.Sections[i+s.Firstsect]
					next += c.Put64(buffer[next:], t.ByteOrder)
				}
			case Magic32:
				next += s.Put32(buffer[next:], t.ByteOrder)
				for i := uint32(0); i < s.Nsect; i++ {
					c := t.Sections[i+s.Firstsect]
					next += c.Put32(buffer[next:], t.ByteOrder)
				}
			default:
				panic(fmt.Sprintf("Unexpected magic number 0x%x", t.Magic))
			}

		} else {
			next += l.Put(buffer[next:], t.ByteOrder)
		}
	}
	return next
}

// UncompressedSize returns the size of the segment with its sections uncompressed, ignoring
// its offset within the file.  The returned size is rounded up to the power of two in align.
func (s *Segment) UncompressedSize(t *FileTOC, align uint64) uint64 {
	sz := uint64(0)
	for j := uint32(0); j < s.Nsect; j++ {
		c := t.Sections[j+s.Firstsect]
		sz += c.UncompressedSize()
	}
	return (sz + align - 1) & uint64(-int64(align))
}

func (s *Section) UncompressedSize() uint64 {
	if !strings.HasPrefix(s.Name, "__z") {
		return s.Size
	}
	b := make([]byte, 12)
	n, err := s.sr.ReadAt(b, 0)
	if err != nil {
		panic("Malformed object file")
	}
	if n != len(b) {
		return s.Size
	}
	if string(b[:4]) == "ZLIB" {
		return binary.BigEndian.Uint64(b[4:12])
	}
	return s.Size
}

func (s *Section) PutData(b []byte) {
	bb := b[0:s.Size]
	n, err := s.sr.ReadAt(bb, 0)
	if err != nil || uint64(n) != s.Size {
		panic("Malformed object file (ReadAt error)")
	}
}

func (s *Section) PutUncompressedData(b []byte) {
	if strings.HasPrefix(s.Name, "__z") {
		bb := make([]byte, 12)
		n, err := s.sr.ReadAt(bb, 0)
		if err != nil {
			panic("Malformed object file")
		}
		if n == len(bb) && string(bb[:4]) == "ZLIB" {
			size := binary.BigEndian.Uint64(bb[4:12])
			// Decompress starting at b[12:]
			r, err := zlib.NewReader(io.NewSectionReader(s, 12, int64(size)-12))
			if err != nil {
				panic("Malformed object file (zlib.NewReader error)")
			}
			n, err := io.ReadFull(r, b[0:size])
			if err != nil {
				panic("Malformed object file (ReadFull error)")
			}
			if uint64(n) != size {
				panic(fmt.Sprintf("PutUncompressedData, expected to read %d bytes, instead read %d", size, n))
			}
			if err := r.Close(); err != nil {
				panic("Malformed object file (Close error)")
			}
			return
		}
	}
	// Not compressed
	s.PutData(b)
}

func (b LoadBytes) String() string {
	var s strings.Builder
	s.WriteString("[")
	for i, a := range b {
		if i > 0 {
			s.WriteString(" ")
			if len(b) > 48 && i >= 16 {
				fmt.Fprintf(&s, "... (%d bytes)", len(b))
				break
			}
		}
		fmt.Fprintf(&s, "%x", a)
	}
	s.WriteString("]")
	return s.String()
}

func (b LoadBytes) Raw() []byte                { return b }
func (b LoadBytes) Copy() LoadBytes            { return LoadBytes(slices.Clone(b)) }
func (b LoadBytes) LoadSize(t *FileTOC) uint32 { return uint32(len(b)) }

func (lc LoadCmd) Put(b []byte, o binary.ByteOrder) int {
	panic(fmt.Sprintf("Put not implemented for %s", lc.String()))
}

func (s LoadCmdBytes) String() string {
	return s.LoadCmd.String() + ": " + s.LoadBytes.String()
}
func (s LoadCmdBytes) Copy() LoadCmdBytes {
	return LoadCmdBytes{LoadCmd: s.LoadCmd, LoadBytes: s.LoadBytes.Copy()}
}

func (s *SegmentHeader) String() string {
	return fmt.Sprintf(
		"Seg %s, len=0x%x, addr=0x%x, memsz=0x%x, offset=0x%x, filesz=0x%x, maxprot=0x%x, prot=0x%x, nsect=%d, flag=0x%x, firstsect=%d",
		s.Name, s.Len, s.Addr, s.Memsz, s.Offset, s.Filesz, s.Maxprot, s.Prot, s.Nsect, s.Flag, s.Firstsect)
}

func (s *Segment) String() string {
	return fmt.Sprintf(
		"Seg %s, len=0x%x, addr=0x%x, memsz=0x%x, offset=0x%x, filesz=0x%x, maxprot=0x%x, prot=0x%x, nsect=%d, flag=0x%x, firstsect=%d",
		s.Name, s.Len, s.Addr, s.Memsz, s.Offset, s.Filesz, s.Maxprot, s.Prot, s.Nsect, s.Flag, s.Firstsect)
}

// Data reads and returns the contents of the segment.
func (s *Segment) Data() ([]byte, error) {
	dat := make([]byte, s.sr.Size())
	n, err := s.sr.ReadAt(dat, 0)
	if n == len(dat) {
		err = nil
	}
	return dat[0:n], err
}

func (s *Segment) Copy() *Segment {
	r := &Segment{SegmentHeader: s.SegmentHeader}
	return r
}
func (s *Segment) CopyZeroed() *Segment {
	r := s.Copy()
	r.Filesz = 0
	r.Offset = 0
	r.Nsect = 0
	r.Firstsect = 0
	if s.Command() == LcSegment64 {
		r.Len = uint32(unsafe.Sizeof(Segment64{}))
	} else {
		r.Len = uint32(unsafe.Sizeof(Segment32{}))
	}
	return r
}

func (s *Segment) LoadSize(t *FileTOC) uint32 {
	if s.Command() == LcSegment64 {
		return uint32(unsafe.Sizeof(Segment64{})) + uint32(s.Nsect)*uint32(unsafe.Sizeof(Section64{}))
	}
	return uint32(unsafe.Sizeof(Segment32{})) + uint32(s.Nsect)*uint32(unsafe.Sizeof(Section32{}))
}

// Open returns a new ReadSeeker reading the segment.
func (s *Segment) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }

// Data reads and returns the contents of the Mach-O section.
func (s *Section) Data() ([]byte, error) {
	dat := make([]byte, s.sr.Size())
	n, err := s.sr.ReadAt(dat, 0)
	if n == len(dat) {
		err = nil
	}
	return dat[0:n], err
}

func (s *Section) Copy() *Section {
	return &Section{SectionHeader: s.SectionHeader}
}

// Open returns a new ReadSeeker reading the Mach-O section.
func (s *Section) Open() io.ReadSeeker { return io.NewSectionReader(s.sr, 0, 1<<63-1) }

// A Dylib represents a Mach-O load dynamic library command.
type Dylib struct {
	DylibCmd
	Name           string
	Time           uint32
	CurrentVersion uint32
	CompatVersion  uint32
}

func (s *Dylib) String() string { return "Dylib " + s.Name }
func (s *Dylib) Copy() *Dylib {
	r := *s
	return &r
}
func (s *Dylib) LoadSize(t *FileTOC) uint32 {
	return uint32(RoundUp(uint64(unsafe.Sizeof(DylibCmd{}))+uint64(len(s.Name)), t.LoadAlign()))
}

type Dylinker struct {
	DylinkerCmd // shared by 3 commands, need the LoadCmd
	Name        string
}

func (s *Dylinker) String() string { return s.DylinkerCmd.LoadCmd.String() + " " + s.Name }
func (s *Dylinker) Copy() *Dylinker {
	return &Dylinker{DylinkerCmd: s.DylinkerCmd, Name: s.Name}
}
func (s *Dylinker) LoadSize(t *FileTOC) uint32 {
	return uint32(RoundUp(uint64(unsafe.Sizeof(DylinkerCmd{}))+uint64(len(s.Name)), t.LoadAlign()))
}

// A Symtab represents a Mach-O symbol table command.
type Symtab struct {
	SymtabCmd
	Syms []Symbol
}

func (s *Symtab) Put(b []byte, o binary.ByteOrder) int {
	o.PutUint32(b[0*4:], uint32(s.LoadCmd))
	o.PutUint32(b[1*4:], s.Len)
	o.PutUint32(b[2*4:], s.Symoff)
	o.PutUint32(b[3*4:], s.Nsyms)
	o.PutUint32(b[4*4:], s.Stroff)
	o.PutUint32(b[5*4:], s.Strsize)
	return 6 * 4
}

func (s *Symtab) String() string { return fmt.Sprintf("Symtab %#v", s.SymtabCmd) }
func (s *Symtab) Copy() *Symtab {
	return &Symtab{SymtabCmd: s.SymtabCmd, Syms: slices.Clone(s.Syms)}
}
func (s *Symtab) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(SymtabCmd{}))
}

type LinkEditData struct {
	LinkEditDataCmd
}

func (s *LinkEditData) String() string { return "LinkEditData " + s.LoadCmd.String() }
func (s *LinkEditData) Copy() *LinkEditData {
	return &LinkEditData{LinkEditDataCmd: s.LinkEditDataCmd}
}
func (s *LinkEditData) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(LinkEditDataCmd{}))
}

type Uuid struct {
	UuidCmd
}

func (s *Uuid) String() string {
	return fmt.Sprintf("Uuid %X-%X-%X-%X-%X",
		s.Id[0:4], s.Id[4:6], s.Id[6:8], s.Id[8:10], s.Id[10:16])
} // 8-4-4-4-12
func (s *Uuid) Copy() *Uuid {
	return &Uuid{UuidCmd: s.UuidCmd}
}
func (s *Uuid) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(UuidCmd{}))
}
func (s *Uuid) Put(b []byte, o binary.ByteOrder) int {
	o.PutUint32(b[0*4:], uint32(s.LoadCmd))
	o.PutUint32(b[1*4:], s.Len)
	copy(b[2*4:], s.Id[0:])
	return int(s.Len)
}

type DyldInfo struct {
	DyldInfoCmd
}

func (s *DyldInfo) String() string { return "DyldInfo " + s.LoadCmd.String() }
func (s *DyldInfo) Copy() *DyldInfo {
	return &DyldInfo{DyldInfoCmd: s.DyldInfoCmd}
}
func (s *DyldInfo) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(DyldInfoCmd{}))
}

type EncryptionInfo struct {
	EncryptionInfoCmd
}

func (s *EncryptionInfo) String() string { return "EncryptionInfo " + s.LoadCmd.String() }
func (s *EncryptionInfo) Copy() *EncryptionInfo {
	return &EncryptionInfo{EncryptionInfoCmd: s.EncryptionInfoCmd}
}
func (s *EncryptionInfo) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(EncryptionInfoCmd{}))
}

// A Dysymtab represents a Mach-O dynamic symbol table command.
type Dysymtab struct {
	DysymtabCmd
	IndirectSyms []uint32 // indices into Symtab.Syms
}

func (s *Dysymtab) String() string { return fmt.Sprintf("Dysymtab %#v", s.DysymtabCmd) }
func (s *Dysymtab) Copy() *Dysymtab {
	return &Dysymtab{DysymtabCmd: s.DysymtabCmd, IndirectSyms: slices.Clone(s.IndirectSyms)}
}
func (s *Dysymtab) LoadSize(t *FileTOC) uint32 {
	return uint32(unsafe.Sizeof(DysymtabCmd{}))
}

// A Rpath represents a Mach-O rpath command.
type Rpath struct {
	LoadCmd
	Path string
}

func (s *Rpath) String() string   { return "Rpath " + s.Path }
func (s *Rpath) Command() LoadCmd { return LcRpath }
func (s *Rpath) Copy() *Rpath {
	return &Rpath{Path: s.Path}
}
func (s *Rpath) LoadSize(t *FileTOC) uint32 {
	return uint32(RoundUp(uint64(unsafe.Sizeof(RpathCmd{}))+uint64(len(s.Path)), t.LoadAlign()))
}

// Open opens the named file using os.Open and prepares it for use as a Mach-O binary.
func Open(name string) (*File, error) {
	f, err := os.Open(name)
	if err != nil {
		return nil, err
	}
	ff, err := NewFile(f)
	if err != nil {
		f.Close()
		return nil, err
	}
	ff.closer = f
	return ff, nil
}

// Close closes the File.
// If the File was created using NewFile directly instead of Open,
// Close has no effect.
func (f *File) Close() error {
	var err error
	if f.closer != nil {
		err = f.closer.Close()
		f.closer = nil
	}
	return err
}

// NewFile creates a new File for accessing a Mach-O binary in an underlying reader.
// The Mach-O binary is expected to start at position 0 in the ReaderAt.
func NewFile(r io.ReaderAt) (*File, error) {
	f := new(File)
	sr := io.NewSectionReader(r, 0, 1<<63-1)

	// Read and decode Mach magic to determine byte order, size.
	// Magic32 and Magic64 differ only in the bottom bit.
	var ident [4]byte
	if _, err := r.ReadAt(ident[0:], 0); err != nil {
		return nil, err
	}
	be := binary.BigEndian.Uint32(ident[0:])
	le := binary.LittleEndian.Uint32(ident[0:])
	switch Magic32 &^ 1 {
	case be &^ 1:
		f.ByteOrder = binary.BigEndian
		f.Magic = be
	case le &^ 1:
		f.ByteOrder = binary.LittleEndian
		f.Magic = le
	default:
		return nil, formatError(0, "invalid magic number be=0x%x, le=0x%x", be, le)
	}

	// Read entire file header.
	if err := binary.Read(sr, f.ByteOrder, &f.FileHeader); err != nil {
		return nil, err
	}

	// Then load commands.
	offset := int64(fileHeaderSize32)
	if f.Magic == Magic64 {
		offset = fileHeaderSize64
	}
	dat := make([]byte, f.SizeCommands)
	if _, err := r.ReadAt(dat, offset); err != nil {
		return nil, err
	}
	f.Loads = make([]Load, f.NCommands)
	bo := f.ByteOrder
	for i := range f.Loads {
		// Each load command begins with uint32 command and length.
		if len(dat) < 8 {
			return nil, formatError(offset, "command block too small, len(dat) = %d", len(dat))
		}
		cmd, siz := LoadCmd(bo.Uint32(dat[0:4])), bo.Uint32(dat[4:8])
		if siz < 8 || siz > uint32(len(dat)) {
			return nil, formatError(offset, "invalid command block size, len(dat)=%d, size=%d", len(dat), siz)
		}
		var cmddat []byte
		cmddat, dat = dat[0:siz], dat[siz:]
		offset += int64(siz)
		var s *Segment
		switch cmd {
		default:
			f.Loads[i] = LoadCmdBytes{LoadCmd(cmd), LoadBytes(cmddat)}

		case LcUuid:
			var hdr UuidCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := &Uuid{UuidCmd: hdr}

			f.Loads[i] = l

		case LcRpath:
			var hdr RpathCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := &Rpath{LoadCmd: hdr.LoadCmd}
			if hdr.Path >= uint32(len(cmddat)) {
				return nil, formatError(offset, "invalid path in rpath command, len(cmddat)=%d, hdr.Path=%d", len(cmddat), hdr.Path)
			}
			l.Path = cstring(cmddat[hdr.Path:])
			f.Loads[i] = l

		case LcLoadDylinker, LcIdDylinker, LcDyldEnvironment:
			var hdr DylinkerCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := new(Dylinker)
			if hdr.Name >= uint32(len(cmddat)) {
				return nil, formatError(offset, "invalid name in dynamic linker command, hdr.Name=%d, len(cmddat)=%d", hdr.Name, len(cmddat))
			}
			l.Name = cstring(cmddat[hdr.Name:])
			l.DylinkerCmd = hdr
			f.Loads[i] = l

		case LcDylib:
			var hdr DylibCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := new(Dylib)
			if hdr.Name >= uint32(len(cmddat)) {
				return nil, formatError(offset, "invalid name in dynamic library command, hdr.Name=%d, len(cmddat)=%d", hdr.Name, len(cmddat))
			}
			l.Name = cstring(cmddat[hdr.Name:])
			l.Time = hdr.Time
			l.CurrentVersion = hdr.CurrentVersion
			l.CompatVersion = hdr.CompatVersion
			f.Loads[i] = l

		case LcSymtab:
			var hdr SymtabCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			strtab := make([]byte, hdr.Strsize)
			if _, err := r.ReadAt(strtab, int64(hdr.Stroff)); err != nil {
				return nil, err
			}
			var symsz int
			if f.Magic == Magic64 {
				symsz = 16
			} else {
				symsz = 12
			}
			symdat := make([]byte, int(hdr.Nsyms)*symsz)
			if _, err := r.ReadAt(symdat, int64(hdr.Symoff)); err != nil {
				return nil, err
			}
			st, err := f.parseSymtab(symdat, strtab, &hdr, offset)
			st.SymtabCmd = hdr
			if err != nil {
				return nil, err
			}
			f.Loads[i] = st
			f.Symtab = st

		case LcDysymtab:
			var hdr DysymtabCmd
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			dat := make([]byte, hdr.Nindirectsyms*4)
			if _, err := r.ReadAt(dat, int64(hdr.Indirectsymoff)); err != nil {
				return nil, err
			}
			x := make([]uint32, hdr.Nindirectsyms)
			if err := binary.Read(bytes.NewReader(dat), bo, x); err != nil {
				return nil, err
			}
			st := new(Dysymtab)
			st.DysymtabCmd = hdr
			st.IndirectSyms = x
			f.Loads[i] = st
			f.Dysymtab = st

		case LcSegment:
			var seg32 Segment32
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &seg32); err != nil {
				return nil, err
			}
			s = new(Segment)
			s.LoadCmd = cmd
			s.Len = siz
			s.Name = cstring(seg32.Name[0:])
			s.Addr = uint64(seg32.Addr)
			s.Memsz = uint64(seg32.Memsz)
			s.Offset = uint64(seg32.Offset)
			s.Filesz = uint64(seg32.Filesz)
			s.Maxprot = seg32.Maxprot
			s.Prot = seg32.Prot
			s.Nsect = seg32.Nsect
			s.Flag = seg32.Flag
			s.Firstsect = uint32(len(f.Sections))
			f.Loads[i] = s
			for i := 0; i < int(s.Nsect); i++ {
				var sh32 Section32
				if err := binary.Read(b, bo, &sh32); err != nil {
					return nil, err
				}
				sh := new(Section)
				sh.Name = cstring(sh32.Name[0:])
				sh.Seg = cstring(sh32.Seg[0:])
				sh.Addr = uint64(sh32.Addr)
				sh.Size = uint64(sh32.Size)
				sh.Offset = sh32.Offset
				sh.Align = sh32.Align
				sh.Reloff = sh32.Reloff
				sh.Nreloc = sh32.Nreloc
				sh.Flags = sh32.Flags
				sh.Reserved1 = sh32.Reserve1
				sh.Reserved2 = sh32.Reserve2
				if err := f.pushSection(sh, r); err != nil {
					return nil, err
				}
			}

		case LcSegment64:
			var seg64 Segment64
			b := bytes.NewReader(cmddat)
			if err := binary.Read(b, bo, &seg64); err != nil {
				return nil, err
			}
			s = new(Segment)
			s.LoadCmd = cmd
			s.Len = siz
			s.Name = cstring(seg64.Name[0:])
			s.Addr = seg64.Addr
			s.Memsz = seg64.Memsz
			s.Offset = seg64.Offset
			s.Filesz = seg64.Filesz
			s.Maxprot = seg64.Maxprot
			s.Prot = seg64.Prot
			s.Nsect = seg64.Nsect
			s.Flag = seg64.Flag
			s.Firstsect = uint32(len(f.Sections))
			f.Loads[i] = s
			for i := 0; i < int(s.Nsect); i++ {
				var sh64 Section64
				if err := binary.Read(b, bo, &sh64); err != nil {
					return nil, err
				}
				sh := new(Section)
				sh.Name = cstring(sh64.Name[0:])
				sh.Seg = cstring(sh64.Seg[0:])
				sh.Addr = sh64.Addr
				sh.Size = sh64.Size
				sh.Offset = sh64.Offset
				sh.Align = sh64.Align
				sh.Reloff = sh64.Reloff
				sh.Nreloc = sh64.Nreloc
				sh.Flags = sh64.Flags
				sh.Reserved1 = sh64.Reserve1
				sh.Reserved2 = sh64.Reserve2
				sh.Reserved3 = sh64.Reserve3
				if err := f.pushSection(sh, r); err != nil {
					return nil, err
				}
			}

		case LcCodeSignature, LcSegmentSplitInfo, LcFunctionStarts,
			LcDataInCode, LcDylibCodeSignDrs:
			var hdr LinkEditDataCmd
			b := bytes.NewReader(cmddat)

			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := new(LinkEditData)

			l.LinkEditDataCmd = hdr
			f.Loads[i] = l

		case LcEncryptionInfo, LcEncryptionInfo64:
			var hdr EncryptionInfoCmd
			b := bytes.NewReader(cmddat)

			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := new(EncryptionInfo)

			l.EncryptionInfoCmd = hdr
			f.Loads[i] = l

		case LcDyldInfo, LcDyldInfoOnly:
			var hdr DyldInfoCmd
			b := bytes.NewReader(cmddat)

			if err := binary.Read(b, bo, &hdr); err != nil {
				return nil, err
			}
			l := new(DyldInfo)

			l.DyldInfoCmd = hdr
			f.Loads[i] = l
		}
		if s != nil {
			s.sr = io.NewSectionReader(r, int64(s.Offset), int64(s.Filesz))
			s.ReaderAt = s.sr
		}
		if f.Loads[i].LoadSize(&f.FileTOC) != siz {
			fmt.Printf("Oops, actual size was %d, calculated was %d, load was %s\n", siz, f.Loads[i].LoadSize(&f.FileTOC), f.Loads[i].String())
			panic("oops")
		}
	}
	return f, nil
}

func (f *File) parseSymtab(symdat, strtab []byte, hdr *SymtabCmd, offset int64) (*Symtab, error) {
	bo := f.ByteOrder
	symtab := make([]Symbol, hdr.Nsyms)
	b := bytes.NewReader(symdat)
	for i := range symtab {
		var n Nlist64
		if f.Magic == Magic64 {
			if err := binary.Read(b, bo, &n); err != nil {
				return nil, err
			}
		} else {
			var n32 Nlist32
			if err := binary.Read(b, bo, &n32); err != nil {
				return nil, err
			}
			n.Name = n32.Name
			n.Type = n32.Type
			n.Sect = n32.Sect
			n.Desc = n32.Desc
			n.Value = uint64(n32.Value)
		}
		sym := &symtab[i]
		if n.Name >= uint32(len(strtab)) {
			return nil, formatError(offset, "invalid name in symbol table, n.Name=%d, len(strtab)=%d", n.Name, len(strtab))
		}
		sym.Name = cstring(strtab[n.Name:])
		sym.Type = n.Type
		sym.Sect = n.Sect
		sym.Desc = n.Desc
		sym.Value = n.Value
	}
	st := new(Symtab)
	st.Syms = symtab
	return st, nil
}

type relocInfo struct {
	Addr   uint32
	Symnum uint32
}

func (f *File) pushSection(sh *Section, r io.ReaderAt) error {
	f.Sections = append(f.Sections, sh)
	sh.sr = io.NewSectionReader(r, int64(sh.Offset), int64(sh.Size))
	sh.ReaderAt = sh.sr

	if sh.Nreloc > 0 {
		reldat := make([]byte, int(sh.Nreloc)*8)
		if _, err := r.ReadAt(reldat, int64(sh.Reloff)); err != nil {
			return err
		}
		b := bytes.NewReader(reldat)

		bo := f.ByteOrder

		sh.Relocs = make([]Reloc, sh.Nreloc)
		for i := range sh.Relocs {
			rel := &sh.Relocs[i]

			var ri relocInfo
			if err := binary.Read(b, bo, &ri); err != nil {
				return err
			}

			if ri.Addr&(1<<31) != 0 { // scattered
				rel.Addr = ri.Addr & (1<<24 - 1)
				rel.Type = uint8((ri.Addr >> 24) & (1<<4 - 1))
				rel.Len = uint8((ri.Addr >> 28) & (1<<2 - 1))
				rel.Pcrel = ri.Addr&(1<<30) != 0
				rel.Value = ri.Symnum
				rel.Scattered = true
			} else {
				switch bo {
				case binary.LittleEndian:
					rel.Addr = ri.Addr
					rel.Value = ri.Symnum & (1<<24 - 1)
					rel.Pcrel = ri.Symnum&(1<<24) != 0
					rel.Len = uint8((ri.Symnum >> 25) & (1<<2 - 1))
					rel.Extern = ri.Symnum&(1<<27) != 0
					rel.Type = uint8((ri.Symnum >> 28) & (1<<4 - 1))
				case binary.BigEndian:
					rel.Addr = ri.Addr
					rel.Value = ri.Symnum >> 8
					rel.Pcrel = ri.Symnum&(1<<7) != 0
					rel.Len = uint8((ri.Symnum >> 5) & (1<<2 - 1))
					rel.Extern = ri.Symnum&(1<<4) != 0
					rel.Type = uint8(ri.Symnum & (1<<4 - 1))
				default:
					panic("unreachable")
				}
			}
		}
	}

	return nil
}

func cstring(b []byte) string {
	i := bytes.IndexByte(b, 0)
	if i == -1 {
		i = len(b)
	}
	return string(b[0:i])
}

// Segment returns the first Segment with the given name, or nil if no such segment exists.
func (f *File) Segment(name string) *Segment {
	for _, l := range f.Loads {
		if s, ok := l.(*Segment); ok && s.Name == name {
			return s
		}
	}
	return nil
}

// Section returns the first section with the given name, or nil if no such
// section exists.
func (f *File) Section(name string) *Section {
	for _, s := range f.Sections {
		if s.Name == name {
			return s
		}
	}
	return nil
}

// DWARF returns the DWARF debug information for the Mach-O file.
func (f *File) DWARF() (*dwarf.Data, error) {
	dwarfSuffix := func(s *Section) string {
		switch {
		case strings.HasPrefix(s.Name, "__debug_"):
			return s.Name[8:]
		case strings.HasPrefix(s.Name, "__zdebug_"):
			return s.Name[9:]
		default:
			return ""
		}

	}
	sectionData := func(s *Section) ([]byte, error) {
		b, err := s.Data()
		if err != nil && uint64(len(b)) < s.Size {
			return nil, err
		}

		if len(b) >= 12 && string(b[:4]) == "ZLIB" {
			dlen := binary.BigEndian.Uint64(b[4:12])
			dbuf := make([]byte, dlen)
			r, err := zlib.NewReader(bytes.NewBuffer(b[12:]))
			if err != nil {
				return nil, err
			}
			if _, err := io.ReadFull(r, dbuf); err != nil {
				return nil, err
			}
			if err := r.Close(); err != nil {
				return nil, err
			}
			b = dbuf
		}
		return b, nil
	}

	// There are many other DWARF sections, but these
	// are the ones the debug/dwarf package uses.
	// Don't bother loading others.
	var dat = map[string][]byte{"abbrev": nil, "info": nil, "str": nil, "line": nil, "ranges": nil}
	for _, s := range f.Sections {
		suffix := dwarfSuffix(s)
		if suffix == "" {
			continue
		}
		if _, ok := dat[suffix]; !ok {
			continue
		}
		b, err := sectionData(s)
		if err != nil {
			return nil, err
		}
		dat[suffix] = b
	}

	d, err := dwarf.New(dat["abbrev"], nil, nil, dat["info"], dat["line"], nil, dat["ranges"], dat["str"])
	if err != nil {
		return nil, err
	}

	// Look for DWARF4 .debug_types sections.
	for i, s := range f.Sections {
		suffix := dwarfSuffix(s)
		if suffix != "types" {
			continue
		}

		b, err := sectionData(s)
		if err != nil {
			return nil, err
		}

		err = d.AddTypes(fmt.Sprintf("types-%d", i), b)
		if err != nil {
			return nil, err
		}
	}

	return d, nil
}

// ImportedSymbols returns the names of all symbols
// referred to by the binary f that are expected to be
// satisfied by other libraries at dynamic load time.
func (f *File) ImportedSymbols() ([]string, error) {
	if f.Dysymtab == nil || f.Symtab == nil {
		return nil, formatError(0, "missing symbol table, f.Dsymtab=%v, f.Symtab=%v", f.Dysymtab, f.Symtab)
	}

	st := f.Symtab
	dt := f.Dysymtab
	var all []string
	for _, s := range st.Syms[dt.Iundefsym : dt.Iundefsym+dt.Nundefsym] {
		all = append(all, s.Name)
	}
	return all, nil
}

// ImportedLibraries returns the paths of all libraries
// referred to by the binary f that are expected to be
// linked with the binary at dynamic link time.
func (f *File) ImportedLibraries() ([]string, error) {
	var all []string
	for _, l := range f.Loads {
		if lib, ok := l.(*Dylib); ok {
			all = append(all, lib.Name)
		}
	}
	return all, nil
}

func RoundUp(x, align uint64) uint64 {
	return uint64((x + align - 1) & -align)
}


================================================
FILE: cmd/splitdwarf/internal/macho/file_test.go
================================================
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package macho

import (
	"reflect"
	"strings"
	"testing"
)

type fileTest struct {
	file        string
	hdr         FileHeader
	loads       []any
	sections    []*SectionHeader
	relocations map[string][]Reloc
}

var fileTests = []fileTest{
	{
		"testdata/gcc-386-darwin-exec",
		FileHeader{0xfeedface, Cpu386, 0x3, 0x2, 0xc, 0x3c0, 0x85},
		[]any{
			&SegmentHeader{LcSegment, 0x38, "__PAGEZERO", 0x0, 0x1000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0},
			&SegmentHeader{LcSegment, 0xc0, "__TEXT", 0x1000, 0x1000, 0x0, 0x1000, 0x7, 0x5, 0x2, 0x0, 0},
			&SegmentHeader{LcSegment, 0xc0, "__DATA", 0x2000, 0x1000, 0x1000, 0x1000, 0x7, 0x3, 0x2, 0x0, 2},
			&SegmentHeader{LcSegment, 0x7c, "__IMPORT", 0x3000, 0x1000, 0x2000, 0x1000, 0x7, 0x7, 0x1, 0x0, 4},
			&SegmentHeader{LcSegment, 0x38, "__LINKEDIT", 0x4000, 0x1000, 0x3000, 0x12c, 0x7, 0x1, 0x0, 0x0, 5},
			nil, // LC_SYMTAB
			nil, // LC_DYSYMTAB
			nil, // LC_LOAD_DYLINKER
			nil, // LC_UUID
			nil, // LC_UNIXTHREAD
			&Dylib{DylibCmd{}, "/usr/lib/libgcc_s.1.dylib", 0x2, 0x10000, 0x10000},
			&Dylib{DylibCmd{}, "/usr/lib/libSystem.B.dylib", 0x2, 0x6f0104, 0x10000},
		},
		[]*SectionHeader{
			{"__text", "__TEXT", 0x1f68, 0x88, 0xf68, 0x2, 0x0, 0x0, 0x80000400, 0, 0, 0},
			{"__cstring", "__TEXT", 0x1ff0, 0xd, 0xff0, 0x0, 0x0, 0x0, 0x2, 0, 0, 0},
			{"__data", "__DATA", 0x2000, 0x14, 0x1000, 0x2, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__dyld", "__DATA", 0x2014, 0x1c, 0x1014, 0x2, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__jump_table", "__IMPORT", 0x3000, 0xa, 0x2000, 0x6, 0x0, 0x0, 0x4000008, 0, 5, 0},
		},
		nil,
	},
	{
		"testdata/gcc-amd64-darwin-exec",
		FileHeader{0xfeedfacf, CpuAmd64, 0x80000003, 0x2, 0xb, 0x568, 0x85},
		[]any{
			&SegmentHeader{LcSegment64, 0x48, "__PAGEZERO", 0x0, 0x100000000, 0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0},
			&SegmentHeader{LcSegment64, 0x1d8, "__TEXT", 0x100000000, 0x1000, 0x0, 0x1000, 0x7, 0x5, 0x5, 0x0, 0},
			&SegmentHeader{LcSegment64, 0x138, "__DATA", 0x100001000, 0x1000, 0x1000, 0x1000, 0x7, 0x3, 0x3, 0x0, 5},
			&SegmentHeader{LcSegment64, 0x48, "__LINKEDIT", 0x100002000, 0x1000, 0x2000, 0x140, 0x7, 0x1, 0x0, 0x0, 8},
			nil, // LC_SYMTAB
			nil, // LC_DYSYMTAB
			nil, // LC_LOAD_DYLINKER
			nil, // LC_UUID
			nil, // LC_UNIXTHREAD
			&Dylib{DylibCmd{}, "/usr/lib/libgcc_s.1.dylib", 0x2, 0x10000, 0x10000},
			&Dylib{DylibCmd{}, "/usr/lib/libSystem.B.dylib", 0x2, 0x6f0104, 0x10000},
		},
		[]*SectionHeader{
			{"__text", "__TEXT", 0x100000f14, 0x6d, 0xf14, 0x2, 0x0, 0x0, 0x80000400, 0, 0, 0},
			{"__symbol_stub1", "__TEXT", 0x100000f81, 0xc, 0xf81, 0x0, 0x0, 0x0, 0x80000408, 0, 6, 0},
			{"__stub_helper", "__TEXT", 0x100000f90, 0x18, 0xf90, 0x2, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__cstring", "__TEXT", 0x100000fa8, 0xd, 0xfa8, 0x0, 0x0, 0x0, 0x2, 0, 0, 0},
			{"__eh_frame", "__TEXT", 0x100000fb8, 0x48, 0xfb8, 0x3, 0x0, 0x0, 0x6000000b, 0, 0, 0},
			{"__data", "__DATA", 0x100001000, 0x1c, 0x1000, 0x3, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__dyld", "__DATA", 0x100001020, 0x38, 0x1020, 0x3, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__la_symbol_ptr", "__DATA", 0x100001058, 0x10, 0x1058, 0x2, 0x0, 0x0, 0x7, 2, 0, 0},
		},
		nil,
	},
	{
		"testdata/gcc-amd64-darwin-exec-debug",
		FileHeader{0xfeedfacf, CpuAmd64, 0x80000003, 0xa, 0x4, 0x5a0, 0},
		[]any{
			nil, // LC_UUID
			&SegmentHeader{LcSegment64, 0x1d8, "__TEXT", 0x100000000, 0x1000, 0x0, 0x0, 0x7, 0x5, 0x5, 0x0, 0},
			&SegmentHeader{LcSegment64, 0x138, "__DATA", 0x100001000, 0x1000, 0x0, 0x0, 0x7, 0x3, 0x3, 0x0, 5},
			&SegmentHeader{LcSegment64, 0x278, "__DWARF", 0x100002000, 0x1000, 0x1000, 0x1bc, 0x7, 0x3, 0x7, 0x0, 8},
		},
		[]*SectionHeader{
			{"__text", "__TEXT", 0x100000f14, 0x0, 0x0, 0x2, 0x0, 0x0, 0x80000400, 0, 0, 0},
			{"__symbol_stub1", "__TEXT", 0x100000f81, 0x0, 0x0, 0x0, 0x0, 0x0, 0x80000408, 0, 6, 0},
			{"__stub_helper", "__TEXT", 0x100000f90, 0x0, 0x0, 0x2, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__cstring", "__TEXT", 0x100000fa8, 0x0, 0x0, 0x0, 0x0, 0x0, 0x2, 0, 0, 0},
			{"__eh_frame", "__TEXT", 0x100000fb8, 0x0, 0x0, 0x3, 0x0, 0x0, 0x6000000b, 0, 0, 0},
			{"__data", "__DATA", 0x100001000, 0x0, 0x0, 0x3, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__dyld", "__DATA", 0x100001020, 0x0, 0x0, 0x3, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__la_symbol_ptr", "__DATA", 0x100001058, 0x0, 0x0, 0x2, 0x0, 0x0, 0x7, 2, 0, 0},
			{"__debug_abbrev", "__DWARF", 0x100002000, 0x36, 0x1000, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_aranges", "__DWARF", 0x100002036, 0x30, 0x1036, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_frame", "__DWARF", 0x100002066, 0x40, 0x1066, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_info", "__DWARF", 0x1000020a6, 0x54, 0x10a6, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_line", "__DWARF", 0x1000020fa, 0x47, 0x10fa, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_pubnames", "__DWARF", 0x100002141, 0x1b, 0x1141, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
			{"__debug_str", "__DWARF", 0x10000215c, 0x60, 0x115c, 0x0, 0x0, 0x0, 0x0, 0, 0, 0},
		},
		nil,
	},
	{
		"testdata/clang-386-darwin-exec-with-rpath",
		FileHeader{0xfeedface, Cpu386, 0x3, 0x2, 0x10, 0x42c, 0x1200085},
		[]any{
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_DYLD_INFO_ONLY
			nil, // LC_SYMTAB
			nil, // LC_DYSYMTAB
			nil, // LC_LOAD_DYLINKER
			nil, // LC_UUID
			nil, // LC_VERSION_MIN_MACOSX
			nil, // LC_SOURCE_VERSION
			nil, // LC_MAIN
			nil, // LC_LOAD_DYLIB
			&Rpath{LcRpath, "/my/rpath"},
			nil, // LC_FUNCTION_STARTS
			nil, // LC_DATA_IN_CODE
		},
		nil,
		nil,
	},
	{
		"testdata/clang-amd64-darwin-exec-with-rpath",
		FileHeader{0xfeedfacf, CpuAmd64, 0x80000003, 0x2, 0x10, 0x4c8, 0x200085},
		[]any{
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_SEGMENT
			nil, // LC_DYLD_INFO_ONLY
			nil, // LC_SYMTAB
			nil, // LC_DYSYMTAB
			nil, // LC_LOAD_DYLINKER
			nil, // LC_UUID
			nil, // LC_VERSION_MIN_MACOSX
			nil, // LC_SOURCE_VERSION
			nil, // LC_MAIN
			nil, // LC_LOAD_DYLIB
			&Rpath{LcRpath, "/my/rpath"},
			nil, // LC_FUNCTION_STARTS
			nil, // LC_DATA_IN_CODE
		},
		nil,
		nil,
	},
	{
		"testdata/clang-386-darwin.obj",
		FileHeader{0xfeedface, Cpu386, 0x3, 0x1, 0x4, 0x138, 0x2000},
		nil,
		nil,
		map[string][]Reloc{
			"__text": {
				{
					Addr:      0x1d,
					Type:      uint8(GENERIC_RELOC_VANILLA),
					Len:       2,
					Pcrel:     true,
					Extern:    true,
					Value:     1,
					Scattered: false,
				},
				{
					Addr:      0xe,
					Type:      uint8(GENERIC_RELOC_LOCAL_SECTDIFF),
					Len:       2,
					Pcrel:     false,
					Value:     0x2d,
					Scattered: true,
				},
				{
					Addr:      0x0,
					Type:      uint8(GENERIC_RELOC_PAIR),
					Len:       2,
					Pcrel:     false,
					Value:     0xb,
					Scattered: true,
				},
			},
		},
	},
	{
		"testdata/clang-amd64-darwin.obj",
		FileHeader{0xfeedfacf, CpuAmd64, 0x3, 0x1, 0x4, 0x200, 0x2000},
		nil,
		nil,
		map[string][]Reloc{
			"__text": {
				{
					Addr:   0x19,
					Type:   uint8(X86_64_RELOC_BRANCH),
					Len:    2,
					Pcrel:  true,
					Extern: true,
					Value:  1,
				},
				{
					Addr:   0xb,
					Type:   uint8(X86_64_RELOC_SIGNED),
					Len:    2,
					Pcrel:  true,
					Extern: false,
					Value:  2,
				},
			},
			"__compact_unwind": {
				{
					Addr:   0x0,
					Type:   uint8(X86_64_RELOC_UNSIGNED),
					Len:    3,
					Pcrel:  false,
					Extern: false,
					Value:  1,
				},
			},
		},
	},
}

func TestOpen(t *testing.T) {
	for i := range fileTests {
		tt := &fileTests[i]

		f, err := Open(tt.file)
		if err != nil {
			t.Error(err)
			continue
		}
		if !reflect.DeepEqual(f.FileHeader, tt.hdr) {
			t.Errorf("open %s:\n\thave %#v\n\twant %#v\n", tt.file, f.FileHeader, tt.hdr)
			continue
		}
		// for i, l := range f.Loads {
		// 	if len(l.Raw()) < 8 {
		// 		t.Errorf("open %s, command %d:\n\tload command %T don't have enough data\n", tt.file, i, l)
		// 	}
		// }
		if tt.loads != nil {
			for i, l := range f.Loads {
				if i >= len(tt.loads) {
					break
				}

				want := tt.loads[i]
				if want == nil {
					continue
				}

				switch l := l.(type) {
				case *Segment:
					have := &l.SegmentHeader
					if !reflect.DeepEqual(have, want) {
						t.Errorf("open %s, command %d:\n\thave %s\n\twant %s\n", tt.file, i, have.String(), want.(*SegmentHeader).String())
					}
				case *Dylib:
					// have := l
					// have.LoadBytes = nil
					// if !reflect.DeepEqual(have, want) {
					// 	t.Errorf("open %s, command %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
					// }
				case *Rpath:
					// have := l
					// have.LoadBytes = nil
					// if !reflect.DeepEqual(have, want) {
					// 	t.Errorf("open %s, command %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
					// }
				default:
					t.Errorf("open %s, command %d: unknown load command\n\thave %#v\n\twant %#v\n", tt.file, i, l, want)
				}
			}
			tn := len(tt.loads)
			fn := len(f.Loads)
			if tn != fn {
				t.Errorf("open %s: len(Loads) = %d, want %d", tt.file, fn, tn)
			}
		}

		if tt.sections != nil {
			for i, sh := range f.Sections {
				if i >= len(tt.sections) {
					break
				}
				have := &sh.SectionHeader
				want := tt.sections[i]
				if !reflect.DeepEqual(have, want) {
					t.Errorf("open %s, section %d:\n\thave %#v\n\twant %#v\n", tt.file, i, have, want)
				}
			}
			tn := len(tt.sections)
			fn := len(f.Sections)
			if tn != fn {
				t.Errorf("open %s: len(Sections) = %d, want %d", tt.file, fn, tn)
			}
		}

		if tt.relocations != nil {
			for i, sh := range f.Sections {
				have := sh.Relocs
				want := tt.relocations[sh.Name]
				if !reflect.DeepEqual(have, want) {
					t.Errorf("open %s, relocations in section %d (%s):\n\thave %#v\n\twant %#v\n", tt.file, i, sh.Name, have, want)
				}
			}
		}
	}
}

func TestOpenFailure(t *testing.T) {
	filename := "file.go"    // not a Mach-O file
	_, err := Open(filename) // don't crash
	if err == nil {
		t.Errorf("open %s: succeeded unexpectedly", filename)
	}
}

func TestOpenFat(t *testing.T) {
	ff, err := OpenFat("testdata/fat-gcc-386-amd64-darwin-exec")
	if err != nil {
		t.Fatal(err)
	}

	if ff.Magic != MagicFat {
		t.Errorf("OpenFat: got magic number %#x, want %#x", ff.Magic, MagicFat)
	}
	if len(ff.Arches) != 2 {
		t.Errorf("OpenFat: got %d architectures, want 2", len(ff.Arches))
	}

	for i := range ff.Arches {
		arch := &ff.Arches[i]
		ftArch := &fileTests[i]

		if arch.Cpu != ftArch.hdr.Cpu || arch.SubCpu != ftArch.hdr.SubCpu {
			t.Errorf("OpenFat: architecture #%d got cpu=%#x subtype=%#x, expected cpu=%#x, subtype=%#x", i, arch.Cpu, arch.SubCpu, ftArch.hdr.Cpu, ftArch.hdr.SubCpu)
		}

		if !reflect.DeepEqual(arch.FileHeader, ftArch.hdr) {
			t.Errorf("OpenFat header:\n\tgot %#v\n\twant %#v\n", arch.FileHeader, ftArch.hdr)
		}
	}
}

func TestOpenFatFailure(t *testing.T) {
	filename := "file.go" // not a Mach-O file
	if _, err := OpenFat(filename); err == nil {
		t.Errorf("OpenFat %s: succeeded unexpectedly", filename)
	}

	filename = "testdata/gcc-386-darwin-exec" // not a fat Mach-O
	ff, err := OpenFat(filename)
	if err == nil {
		t.Errorf("OpenFat %s: expected error, got nil", filename)
	}
	if _, ok := err.(*FormatError); !ok {
		t.Errorf("OpenFat %s: expected FormatError, got %v", filename, err)
	}

	ferr := err.(*FormatError)
	if !strings.Contains(ferr.String(), "not a fat") {
		t.Errorf("OpenFat %s: expected error containing 'not a fat', got %s", filename, ferr.String())
	}

	if ff != nil {
		t.Errorf("OpenFat %s: got %v, want nil", filename, ff)
	}
}

func TestRelocTypeString(t *testing.T) {
	if X86_64_RELOC_BRANCH.String() != "X86_64_RELOC_BRANCH" {
		t.Errorf("got %v, want %v", X86_64_RELOC_BRANCH.String(), "X86_64_RELOC_BRANCH")
	}
	if X86_64_RELOC_BRANCH.GoString() != "macho.X86_64_RELOC_BRANCH" {
		t.Errorf("got %v, want %v", X86_64_RELOC_BRANCH.GoString(), "macho.X86_64_RELOC_BRANCH")
	}
}

func TestTypeString(t *testing.T) {
	if MhExecute.String() != "Exec" {
		t.Errorf("got %v, want %v", MhExecute.String(), "Exec")
	}
	if MhExecute.GoString() != "macho.Exec" {
		t.Errorf("got %v, want %v", MhExecute.GoString(), "macho.Exec")
	}
}


================================================
FILE: cmd/splitdwarf/internal/macho/macho.go
================================================
// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Mach-O header data structures
// http://developer.apple.com/mac/library/documentation/DeveloperTools/Conceptual/MachORuntime/Reference/reference.html

package macho

import (
	"encoding/binary"
	"strconv"
)

// A FileHeader represents a Mach-O file header.
type FileHeader struct {
	Magic        uint32
	Cpu          Cpu
	SubCpu       uint32
	Type         HdrType
	NCommands    uint32 // number of load commands
	SizeCommands uint32 // size of all the load commands, not including this header.
	Flags        HdrFlags
}

func (h *FileHeader) Put(b []byte, o binary.ByteOrder) int {
	o.PutUint32(b[0:], h.Magic)
	o.PutUint32(b[4:], uint32(h.Cpu))
	o.PutUint32(b[8:], h.SubCpu)
	o.PutUint32(b[12:], uint32(h.Type))
	o.PutUint32(b[16:], h.NCommands)
	o.PutUint32(b[20:], h.SizeCommands)
	o.PutUint32(b[24:], uint32(h.Flags))
	if h.Magic == Magic32 {
		return 28
	}
	o.PutUint32(b[28:], 0)
	return 32
}

const (
	fileHeaderSize32 = 7 * 4
	fileHeaderSize64 = 8 * 4
)

const (
	Magic32  uint32 = 0xfeedface
	Magic64  uint32 = 0xfeedfacf
	MagicFat uint32 = 0xcafebabe
)

type HdrFlags uint32
type SegFlags uint32
type SecFlags uint32

// A HdrType is the Mach-O file type, e.g. an object file, executable, or dynamic library.
type HdrType uint32

const ( // SNAKE_CASE to CamelCase translation from C names
	MhObject  HdrType = 1
	MhExecute HdrType = 2
	MhCore    HdrType = 4
	MhDylib   HdrType = 6
	MhBundle  HdrType = 8
	MhDsym    HdrType = 0xa
)

var typeStrings = []intName{
	{uint32(MhObject), "Obj"},
	{uint32(MhExecute), "Exec"},
	{uint32(MhDylib), "Dylib"},
	{uint32(MhBundle), "Bundle"},
	{uint32(MhDsym), "Dsym"},
}

func (t HdrType) String() string   { return stringName(uint32(t), typeStrings, false) }
func (t HdrType) GoString() string { return stringName(uint32(t), typeStrings, true) }

// A Cpu is a Mach-O cpu type.
type Cpu uint32

const cpuArch64 = 0x01000000

const (
	Cpu386   Cpu = 7
	CpuAmd64 Cpu = Cpu386 | cpuArch64
	CpuArm   Cpu = 12
	CpuArm64 Cpu = CpuArm | cpuArch64
	CpuPpc   Cpu = 18
	CpuPpc64 Cpu = CpuPpc | cpuArch64
)

var cpuStrings = []intName{
	{uint32(Cpu386), "Cpu386"},
	{uint32(CpuAmd64), "CpuAmd64"},
	{uint32(CpuArm), "CpuArm"},
	{uint32(CpuArm64), "CpuArm64"},
	{uint32(CpuPpc), "CpuPpc"},
	{uint32(CpuPpc64), "CpuPpc64"},
}

func (i Cpu) String() string   { return stringName(uint32(i), cpuStrings, false) }
func (i Cpu) GoString() string { return stringName(uint32(i), cpuStrings, true) }

// A LoadCmd is a Mach-O load command.
type LoadCmd uint32

func (c LoadCmd) Command() LoadCmd { return c }

const ( // SNAKE_CASE to CamelCase translation from C names
	// Note 3 and 8 are obsolete
	LcSegment            LoadCmd = 0x1
	LcSymtab             LoadCmd = 0x2
	LcThread             LoadCmd = 0x4
	LcUnixthread         LoadCmd = 0x5 // thread+stack
	LcDysymtab           LoadCmd = 0xb
	LcDylib              LoadCmd = 0xc // load dylib command
	LcIdDylib            LoadCmd = 0xd // dynamically linked shared lib ident
	LcLoadDylinker       LoadCmd = 0xe // load a dynamic linker
	LcIdDylinker         LoadCmd = 0xf // id dylinker command (not load dylinker command)
	LcSegment64          LoadCmd = 0x19
	LcUuid               LoadCmd = 0x1b
	LcCodeSignature      LoadCmd = 0x1d
	LcSegmentSplitInfo   LoadCmd = 0x1e
	LcRpath              LoadCmd = 0x8000001c
	LcEncryptionInfo     LoadCmd = 0x21
	LcDyldInfo           LoadCmd = 0x22
	LcDyldInfoOnly       LoadCmd = 0x80000022
	LcVersionMinMacosx   LoadCmd = 0x24
	LcVersionMinIphoneos LoadCmd = 0x25
	LcFunctionStarts     LoadCmd = 0x26
	LcDyldEnvironment    LoadCmd = 0x27
	LcMain               LoadCmd = 0x80000028 // replacement for UnixThread
	LcDataInCode         LoadCmd = 0x29       // There are non-instructions in text
	LcSourceVersion      LoadCmd = 0x2a       // Source version used to build binary
	LcDylibCodeSignDrs   LoadCmd = 0x2b
	LcEncryptionInfo64   LoadCmd = 0x2c
	LcVersionMinTvos     LoadCmd = 0x2f
	LcVersionMinWatchos  LoadCmd = 0x30
)

var cmdStrings = []intName{
	{uint32(LcSegment), "LoadCmdSegment"},
	{uint32(LcThread), "LoadCmdThread"},
	{uint32(LcUnixthread), "LoadCmdUnixThread"},
	{uint32(LcDylib), "LoadCmdDylib"},
	{uint32(LcIdDylib), "LoadCmdIdDylib"},
	{uint32(LcLoadDylinker), "LoadCmdLoadDylinker"},
	{uint32(LcIdDylinker), "LoadCmdIdDylinker"},
	{uint32(LcSegment64), "LoadCmdSegment64"},
	{uint32(LcUuid), "LoadCmdUuid"},
	{uint32(LcRpath), "LoadCmdRpath"},
	{uint32(LcDyldEnvironment), "LoadCmdDyldEnv"},
	{uint32(LcMain), "LoadCmdMain"},
	{uint32(LcDataInCode), "LoadCmdDataInCode"},
	{uint32(LcSourceVersion), "LoadCmdSourceVersion"},
	{uint32(LcDyldInfo), "LoadCmdDyldInfo"},
	{uint32(LcDyldInfoOnly), "LoadCmdDyldInfoOnly"},
	{uint32(LcVersionMinMacosx), "LoadCmdMinOsx"},
	{uint32(LcFunctionStarts), "LoadCmdFunctionStarts"},
}

func (i LoadCmd) String() string   { return stringName(uint32(i), cmdStrings, false) }
func (i LoadCmd) GoString() string { return stringName(uint32(i), cmdStrings, true) }

type (
	// A Segment32 is a 32-bit Mach-O segment load command.
	Segment32 struct {
		LoadCmd
		Len     uint32
		Name    [16]byte
		Addr    uint32
		Memsz   uint32
		Offset  uint32
		Filesz  uint32
		Maxprot uint32
		Prot    uint32
		Nsect   uint32
		Flag    SegFlags
	}

	// A Segment64 is a 64-bit Mach-O segment load command.
	Segment64 struct {
		LoadCmd
		Len     uint32
		Name    [16]byte
		Addr    uint64
		Memsz   uint64
		Offset  uint64
		Filesz  uint64
		Maxprot uint32
		Prot    uint32
		Nsect   uint32
		Flag    SegFlags
	}

	// A SymtabCmd is a Mach-O symbol table command.
	SymtabCmd struct {
		LoadCmd
		Len     uint32
		Symoff  uint32
		Nsyms   uint32
		Stroff  uint32
		Strsize uint32
	}

	// A DysymtabCmd is a Mach-O dynamic symbol table command.
	DysymtabCmd struct {
		LoadCmd
		Len            uint32
		Ilocalsym      uint32
		Nlocalsym      uint32
		Iextdefsym     uint32
		Nextdefsym     uint32
		Iundefsym      uint32
		Nundefsym      uint32
		Tocoffset      uint32
		Ntoc           uint32
		Modtaboff      uint32
		Nmodtab        uint32
		Extrefsymoff   uint32
		Nextrefsyms    uint32
		Indirectsymoff uint32
		Nindirectsyms  uint32
		Extreloff      uint32
		Nextrel        uint32
		Locreloff      uint32
		Nlocrel        uint32
	}

	// A DylibCmd is a Mach-O load dynamic library command.
	DylibCmd struct {
		LoadCmd
		Len            uint32
		Name           uint32
		Time           uint32
		CurrentVersion uint32
		CompatVersion  uint32
	}

	// A DylinkerCmd is a Mach-O load dynamic linker or environment command.
	DylinkerCmd struct {
		LoadCmd
		Len  uint32
		Name uint32
	}

	// A RpathCmd is a Mach-O rpath command.
	RpathCmd struct {
		LoadCmd
		Len  uint32
		Path uint32
	}

	// A Thread is a Mach-O thread state command.
	Thread struct {
		LoadCmd
		Len  uint32
		Type uint32
		Data []uint32
	}

	// LC_DYLD_INFO, LC_DYLD_INFO_ONLY
	DyldInfoCmd struct {
		LoadCmd
		Len                      uint32
		RebaseOff, RebaseLen     uint32 // file offset and length; data contains segment indices
		BindOff, BindLen         uint32 // file offset and length; data contains segment indices
		WeakBindOff, WeakBindLen uint32 // file offset and length
		LazyBindOff, LazyBindLen uint32 // file offset and length
		ExportOff, ExportLen     uint32 // file offset and length
	}

	// LC_CODE_SIGNATURE, LC_SEGMENT_SPLIT_INFO, LC_FUNCTION_STARTS, LC_DATA_IN_CODE, LC_DYLIB_CODE_SIGN_DRS
	LinkEditDataCmd struct {
		LoadCmd
		Len              uint32
		DataOff, DataLen uint32 // file offset and length
	}

	// LC_ENCRYPTION_INFO, LC_ENCRYPTION_INFO_64
	EncryptionInfoCmd struct {
		LoadCmd
		Len                uint32
		CryptOff, CryptLen uint32 // file offset and length
		CryptId            uint32
	}

	UuidCmd struct {
		LoadCmd
		Len uint32
		Id  [16]byte
	}

	// TODO Commands below not fully supported yet.

	EntryPointCmd struct {
		LoadCmd
		Len       uint32
		EntryOff  uint64 // file offset
		StackSize uint64 // if not zero, initial stack size
	}

	NoteCmd struct {
		LoadCmd
		Len            uint32
		Name           [16]byte
		Offset, Filesz uint64 // file offset and length
	}
)

const (
	FlagNoUndefs              HdrFlags = 0x1
	FlagIncrLink              HdrFlags = 0x2
	FlagDyldLink              HdrFlags = 0x4
	FlagBindAtLoad            HdrFlags = 0x8
	FlagPrebound              HdrFlags = 0x10
	FlagSplitSegs             HdrFlags = 0x20
	FlagLazyInit              HdrFlags = 0x40
	FlagTwoLevel              HdrFlags = 0x80
	FlagForceFlat             HdrFlags = 0x100
	FlagNoMultiDefs           HdrFlags = 0x200
	FlagNoFixPrebinding       HdrFlags = 0x400
	FlagPrebindable           HdrFlags = 0x800
	FlagAllModsBound          HdrFlags = 0x1000
	FlagSubsectionsViaSymbols HdrFlags = 0x2000
	FlagCanonical             HdrFlags = 0x4000
	FlagWeakDefines           HdrFlags = 0x8000
	FlagBindsToWeak           HdrFlags = 0x10000
	FlagAllowStackExecution   HdrFlags = 0x20000
	FlagRootSafe              HdrFlags = 0x40000
	FlagSetuidSafe            HdrFlags = 0x80000
	FlagNoReexportedDylibs    HdrFlags = 0x100000
	FlagPIE                   HdrFlags = 0x200000
	FlagDeadStrippableDylib   HdrFlags = 0x400000
	FlagHasTLVDescriptors     HdrFlags = 0x800000
	FlagNoHeapExecution       HdrFlags = 0x1000000
	FlagAppExtensionSafe      HdrFlags = 0x2000000
)

// A Section32 is a 32-bit Mach-O section header.
type Section32 struct {
	Name     [16]byte
	Seg      [16]byte
	Addr     uint32
	Size     uint32
	Offset   uint32
	Align    uint32
	Reloff   uint32
	Nreloc   uint32
	Flags    SecFlags
	Reserve1 uint32
	Reserve2 uint32
}

// A Section64 is a 64-bit Mach-O section header.
type Section64 struct {
	Name     [16]byte
	Seg      [16]byte
	Addr     uint64
	Size     uint64
	Offset   uint32
	Align    uint32
	Reloff   uint32
	Nreloc   uint32
	Flags    SecFlags
	Reserve1 uint32
	Reserve2 uint32
	Reserve3 uint32
}

// An Nlist32 is a Mach-O 32-bit symbol table entry.
type Nlist32 struct {
	Name  uint32
	Type  uint8
	Sect  uint8
	Desc  uint16
	Value uint32
}

// An Nlist64 is a Mach-O 64-bit symbol table entry.
type Nlist64 struct {
	Name  uint32
	Type  uint8
	Sect  uint8
	Desc  uint16
	Value uint64
}

func (n *Nlist64) Put64(b []byte, o binary.ByteOrder) uint32 {
	o.PutUint32(b[0:], n.Name)
	b[4] = byte(n.Type)
	b[5] = byte(n.Sect)
	o.PutUint16(b[6:], n.Desc)
	o.PutUint64(b[8:], n.Value)
	return 8 + 8
}

func (n *Nlist64) Put32(b []byte, o binary.ByteOrder) uint32 {
	o.PutUint32(b[0:], n.Name)
	b[4] = byte(n.Type)
	b[5] = byte(n.Sect)
	o.PutUint16(b[6:], n.Desc)
	o.PutUint32(b[8:], uint32(n.Value))
	return 8 + 4
}

// Regs386 is the Mach-O 386 register structure.
type Regs386 struct {
	AX    uint32
	BX    uint32
	CX    uint32
	DX    uint32
	DI    uint32
	SI    uint32
	BP    uint32
	SP    uint32
	SS    uint32
	FLAGS uint32
	IP    uint32
	CS    uint32
	DS    uint32
	ES    uint32
	FS    uint32
	GS    uint32
}

// RegsAMD64 is the Mach-O AMD64 register structure.
type RegsAMD64 struct {
	AX    uint64
	BX    uint64
	CX    uint64
	DX    uint64
	DI    uint64
	SI    uint64
	BP    uint64
	SP    uint64
	R8    uint64
	R9    uint64
	R10   uint64
	R11   uint64
	R12   uint64
	R13   uint64
	R14   uint64
	R15   uint64
	IP    uint64
	FLAGS uint64
	CS    uint64
	FS    uint64
	GS    uint64
}

type intName struct {
	i uint32
	s string
}

func stringName(i uint32, names []intName, goSyntax bool) string {
	for _, n := range names {
		if n.i == i {
			if goSyntax {
				return "macho." + n.s
			}
			return n.s
		}
	}
	return "0x" + strconv.FormatUint(uint64(i), 16)
}


================================================
FILE: cmd/splitdwarf/internal/macho/reloctype.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package macho

//go:generate stringer -type=RelocTypeGeneric,RelocTypeX86_64,RelocTypeARM,RelocTypeARM64 -output reloctype_string.go

type RelocTypeGeneric int

const (
	GENERIC_RELOC_VANILLA        RelocTypeGeneric = 0
	GENERIC_RELOC_PAIR           RelocTypeGeneric = 1
	GENERIC_RELOC_SECTDIFF       RelocTypeGeneric = 2
	GENERIC_RELOC_PB_LA_PTR      RelocTypeGeneric = 3
	GENERIC_RELOC_LOCAL_SECTDIFF RelocTypeGeneric = 4
	GENERIC_RELOC_TLV            RelocTypeGeneric = 5
)

func (r RelocTypeGeneric) GoString() string { return "macho." + r.String() }

type RelocTypeX86_64 int

const (
	X86_64_RELOC_UNSIGNED   RelocTypeX86_64 = 0
	X86_64_RELOC_SIGNED     RelocTypeX86_64 = 1
	X86_64_RELOC_BRANCH     RelocTypeX86_64 = 2
	X86_64_RELOC_GOT_LOAD   RelocTypeX86_64 = 3
	X86_64_RELOC_GOT        RelocTypeX86_64 = 4
	X86_64_RELOC_SUBTRACTOR RelocTypeX86_64 = 5
	X86_64_RELOC_SIGNED_1   RelocTypeX86_64 = 6
	X86_64_RELOC_SIGNED_2   RelocTypeX86_64 = 7
	X86_64_RELOC_SIGNED_4   RelocTypeX86_64 = 8
	X86_64_RELOC_TLV        RelocTypeX86_64 = 9
)

func (r RelocTypeX86_64) GoString() string { return "macho." + r.String() }

type RelocTypeARM int

const (
	ARM_RELOC_VANILLA        RelocTypeARM = 0
	ARM_RELOC_PAIR           RelocTypeARM = 1
	ARM_RELOC_SECTDIFF       RelocTypeARM = 2
	ARM_RELOC_LOCAL_SECTDIFF RelocTypeARM = 3
	ARM_RELOC_PB_LA_PTR      RelocTypeARM = 4
	ARM_RELOC_BR24           RelocTypeARM = 5
	ARM_THUMB_RELOC_BR22     RelocTypeARM = 6
	ARM_THUMB_32BIT_BRANCH   RelocTypeARM = 7
	ARM_RELOC_HALF           RelocTypeARM = 8
	ARM_RELOC_HALF_SECTDIFF  RelocTypeARM = 9
)

func (r RelocTypeARM) GoString() string { return "macho." + r.String() }

type RelocTypeARM64 int

const (
	ARM64_RELOC_UNSIGNED            RelocTypeARM64 = 0
	ARM64_RELOC_SUBTRACTOR          RelocTypeARM64 = 1
	ARM64_RELOC_BRANCH26            RelocTypeARM64 = 2
	ARM64_RELOC_PAGE21              RelocTypeARM64 = 3
	ARM64_RELOC_PAGEOFF12           RelocTypeARM64 = 4
	ARM64_RELOC_GOT_LOAD_PAGE21     RelocTypeARM64 = 5
	ARM64_RELOC_GOT_LOAD_PAGEOFF12  RelocTypeARM64 = 6
	ARM64_RELOC_POINTER_TO_GOT      RelocTypeARM64 = 7
	ARM64_RELOC_TLVP_LOAD_PAGE21    RelocTypeARM64 = 8
	ARM64_RELOC_TLVP_LOAD_PAGEOFF12 RelocTypeARM64 = 9
	ARM64_RELOC_ADDEND              RelocTypeARM64 = 10
)

func (r RelocTypeARM64) GoString() string { return "macho." + r.String() }


================================================
FILE: cmd/splitdwarf/internal/macho/reloctype_string.go
================================================
// Code generated by "stringer -type=RelocTypeGeneric,RelocTypeX86_64,RelocTypeARM,RelocTypeARM64 -output reloctype_string.go"; DO NOT EDIT.

package macho

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[GENERIC_RELOC_VANILLA-0]
	_ = x[GENERIC_RELOC_PAIR-1]
	_ = x[GENERIC_RELOC_SECTDIFF-2]
	_ = x[GENERIC_RELOC_PB_LA_PTR-3]
	_ = x[GENERIC_RELOC_LOCAL_SECTDIFF-4]
	_ = x[GENERIC_RELOC_TLV-5]
}

const _RelocTypeGeneric_name = "GENERIC_RELOC_VANILLAGENERIC_RELOC_PAIRGENERIC_RELOC_SECTDIFFGENERIC_RELOC_PB_LA_PTRGENERIC_RELOC_LOCAL_SECTDIFFGENERIC_RELOC_TLV"

var _RelocTypeGeneric_index = [...]uint8{0, 21, 39, 61, 84, 112, 129}

func (i RelocTypeGeneric) String() string {
	if i < 0 || i >= RelocTypeGeneric(len(_RelocTypeGeneric_index)-1) {
		return "RelocTypeGeneric(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _RelocTypeGeneric_name[_RelocTypeGeneric_index[i]:_RelocTypeGeneric_index[i+1]]
}
func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[X86_64_RELOC_UNSIGNED-0]
	_ = x[X86_64_RELOC_SIGNED-1]
	_ = x[X86_64_RELOC_BRANCH-2]
	_ = x[X86_64_RELOC_GOT_LOAD-3]
	_ = x[X86_64_RELOC_GOT-4]
	_ = x[X86_64_RELOC_SUBTRACTOR-5]
	_ = x[X86_64_RELOC_SIGNED_1-6]
	_ = x[X86_64_RELOC_SIGNED_2-7]
	_ = x[X86_64_RELOC_SIGNED_4-8]
	_ = x[X86_64_RELOC_TLV-9]
}

const _RelocTypeX86_64_name = "X86_64_RELOC_UNSIGNEDX86_64_RELOC_SIGNEDX86_64_RELOC_BRANCHX86_64_RELOC_GOT_LOADX86_64_RELOC_GOTX86_64_RELOC_SUBTRACTORX86_64_RELOC_SIGNED_1X86_64_RELOC_SIGNED_2X86_64_RELOC_SIGNED_4X86_64_RELOC_TLV"

var _RelocTypeX86_64_index = [...]uint8{0, 21, 40, 59, 80, 96, 119, 140, 161, 182, 198}

func (i RelocTypeX86_64) String() string {
	if i < 0 || i >= RelocTypeX86_64(len(_RelocTypeX86_64_index)-1) {
		return "RelocTypeX86_64(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _RelocTypeX86_64_name[_RelocTypeX86_64_index[i]:_RelocTypeX86_64_index[i+1]]
}
func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[ARM_RELOC_VANILLA-0]
	_ = x[ARM_RELOC_PAIR-1]
	_ = x[ARM_RELOC_SECTDIFF-2]
	_ = x[ARM_RELOC_LOCAL_SECTDIFF-3]
	_ = x[ARM_RELOC_PB_LA_PTR-4]
	_ = x[ARM_RELOC_BR24-5]
	_ = x[ARM_THUMB_RELOC_BR22-6]
	_ = x[ARM_THUMB_32BIT_BRANCH-7]
	_ = x[ARM_RELOC_HALF-8]
	_ = x[ARM_RELOC_HALF_SECTDIFF-9]
}

const _RelocTypeARM_name = "ARM_RELOC_VANILLAARM_RELOC_PAIRARM_RELOC_SECTDIFFARM_RELOC_LOCAL_SECTDIFFARM_RELOC_PB_LA_PTRARM_RELOC_BR24ARM_THUMB_RELOC_BR22ARM_THUMB_32BIT_BRANCHARM_RELOC_HALFARM_RELOC_HALF_SECTDIFF"

var _RelocTypeARM_index = [...]uint8{0, 17, 31, 49, 73, 92, 106, 126, 148, 162, 185}

func (i RelocTypeARM) String() string {
	if i < 0 || i >= RelocTypeARM(len(_RelocTypeARM_index)-1) {
		return "RelocTypeARM(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _RelocTypeARM_name[_RelocTypeARM_index[i]:_RelocTypeARM_index[i+1]]
}
func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[ARM64_RELOC_UNSIGNED-0]
	_ = x[ARM64_RELOC_SUBTRACTOR-1]
	_ = x[ARM64_RELOC_BRANCH26-2]
	_ = x[ARM64_RELOC_PAGE21-3]
	_ = x[ARM64_RELOC_PAGEOFF12-4]
	_ = x[ARM64_RELOC_GOT_LOAD_PAGE21-5]
	_ = x[ARM64_RELOC_GOT_LOAD_PAGEOFF12-6]
	_ = x[ARM64_RELOC_POINTER_TO_GOT-7]
	_ = x[ARM64_RELOC_TLVP_LOAD_PAGE21-8]
	_ = x[ARM64_RELOC_TLVP_LOAD_PAGEOFF12-9]
	_ = x[ARM64_RELOC_ADDEND-10]
}

const _RelocTypeARM64_name = "ARM64_RELOC_UNSIGNEDARM64_RELOC_SUBTRACTORARM64_RELOC_BRANCH26ARM64_RELOC_PAGE21ARM64_RELOC_PAGEOFF12ARM64_RELOC_GOT_LOAD_PAGE21ARM64_RELOC_GOT_LOAD_PAGEOFF12ARM64_RELOC_POINTER_TO_GOTARM64_RELOC_TLVP_LOAD_PAGE21ARM64_RELOC_TLVP_LOAD_PAGEOFF12ARM64_RELOC_ADDEND"

var _RelocTypeARM64_index = [...]uint16{0, 20, 42, 62, 80, 101, 128, 158, 184, 212, 243, 261}

func (i RelocTypeARM64) String() string {
	if i < 0 || i >= RelocTypeARM64(len(_RelocTypeARM64_index)-1) {
		return "RelocTypeARM64(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _RelocTypeARM64_name[_RelocTypeARM64_index[i]:_RelocTypeARM64_index[i+1]]
}


================================================
FILE: cmd/splitdwarf/internal/macho/testdata/hello.c
================================================
#include <stdio.h>

int
main(void)
{
	printf("hello, world\n");
	return 0;
}


================================================
FILE: cmd/splitdwarf/splitdwarf.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd

/*
Splitdwarf uncompresses and copies the DWARF segment of a Mach-O
executable into the "dSYM" file expected by lldb and ports of gdb
on OSX.

Usage: splitdwarf osxMachoFile [ osxDsymFile ]

Unless a dSYM file name is provided on the command line,
splitdwarf will place it where the OSX tools expect it, in
"<osxMachoFile>.dSYM/Contents/Resources/DWARF/<osxMachoFile>",
creating directories as necessary.
*/
package main // import "golang.org/x/tools/cmd/splitdwarf"

import (
	"crypto/sha256"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"syscall"

	"golang.org/x/tools/cmd/splitdwarf/internal/macho"
)

const (
	pageAlign = 12 // 4096 = 1 << 12
)

func note(format string, why ...any) {
	fmt.Fprintf(os.Stderr, format+"\n", why...)
}

func fail(format string, why ...any) {
	note(format, why...)
	os.Exit(1)
}

// splitdwarf inputexe [ outputdwarf ]
func main() {
	if len(os.Args) < 2 || len(os.Args) > 3 {
		fmt.Printf(`
Usage: %s input_exe [ output_dsym ]
Reads the executable input_exe, uncompresses and copies debugging
information into output_dsym. If output_dsym is not specified,
the path
      input_exe.dSYM/Contents/Resources/DWARF/input_exe
is used instead.  That is the path that gdb and lldb expect
on OSX.  Input_exe needs a UUID segment; if that is missing,
then one is created and added.  In that case, the permissions
for input_exe need to allow writing.
`, os.Args[0])
		return
	}

	// Read input, find DWARF, be sure it looks right
	inputExe := os.Args[1]
	exeFile, err := os.Open(inputExe)
	if err != nil {
		fail("%v", err)
	}
	exeMacho, err := macho.NewFile(exeFile)
	if err != nil {
		fail("(internal) Couldn't create macho, %v", err)
	}
	// Postpone dealing with output till input is known-good

	// describe(&exeMacho.FileTOC)

	// Offsets into __LINKEDIT:
	//
	// Command LC_SYMTAB =
	//  (1) number of symbols at file offset (within link edit section) of 16-byte symbol table entries
	// struct {
	//  StringTableIndex uint32
	//  Type, SectionIndex uint8
	//  Description uint16
	//  Value uint64
	// }
	//
	// (2) string table offset and size.  Strings are zero-byte terminated.  First must be " ".
	//
	// Command LC_DYSYMTAB = indices within symtab (above), except for IndSym
	//   IndSym Offset = file offset (within link edit section) of 4-byte indices within symtab.
	//
	// Section __TEXT.__symbol_stub1.
	//   Offset and size (Reserved2) locate and describe a table for this section.
	//   Symbols beginning at IndirectSymIndex (Reserved1) (see LC_DYSYMTAB.IndSymOffset) refer to this table.
	//   (These table entries are apparently PLTs [Procedure Linkage Table/Trampoline])
	//
	// Section __DATA.__nl_symbol_ptr.
	//   Reserved1 seems to be an index within the Indirect symbols (see LC_DYSYMTAB.IndSymOffset)
	//   Some of these symbols appear to be duplicates of other indirect symbols appearing early
	//
	// Section __DATA.__la_symbol_ptr.
	//   Reserved1 seems to be an index within the Indirect symbols (see LC_DYSYMTAB.IndSymOffset)
	//   Some of these symbols appear to be duplicates of other indirect symbols appearing early
	//

	// Create a File for the output dwarf.
	// Copy header, file type is MH_DSYM
	// Copy the relevant load commands

	// LoadCmdUuid
	// Symtab -- very abbreviated (Use DYSYMTAB Iextdefsym, Nextdefsym to identify these).
	// Segment __PAGEZERO
	// Segment __TEXT (zero the size, zero the offset of each section)
	// Segment __DATA (zero the size, zero the offset of each section)
	// Segment __LINKEDIT (contains the symbols and strings from Symtab)
	// Segment __DWARF (uncompressed)

	var uuid *macho.Uuid
	for _, l := range exeMacho.Loads {
		switch l.Command() {
		case macho.LcUuid:
			uuid = l.(*macho.Uuid)
		}
	}

	// Ensure a given load is not nil
	nonnilC := func(l macho.Load, s string) {
		if l == nil {
			fail("input file %s lacks load command %s", inputExe, s)
		}
	}

	// Find a segment by name and ensure it is not nil
	nonnilS := func(s string) *macho.Segment {
		l := exeMacho.Segment(s)
		if l == nil {
			fail("input file %s lacks segment %s", inputExe, s)
		}
		return l
	}

	newtoc := exeMacho.FileTOC.DerivedCopy(macho.MhDsym, 0)

	symtab := exeMacho.Symtab
	dysymtab := exeMacho.Dysymtab // Not appearing in output, but necessary to construct output
	nonnilC(symtab, "symtab")
	nonnilC(dysymtab, "dysymtab")
	text := nonnilS("__TEXT")
	data := nonnilS("__DATA")
	linkedit := nonnilS("__LINKEDIT")
	pagezero := nonnilS("__PAGEZERO")

	newtext := text.CopyZeroed()
	newdata := data.CopyZeroed()
	newsymtab := symtab.Copy()

	// Linkedit segment contain symbols and strings;
	// Symtab refers to offsets into linkedit.
	// This next bit initializes newsymtab and sets up data structures for the linkedit segment
	linkeditsyms := []macho.Nlist64{}
	linkeditstrings := []string{}

	// Linkedit will begin at the second page, i.e., offset is one page from beginning
	// Symbols come first
	linkeditsymbase := uint32(1) << pageAlign

	// Strings come second, offset by the number of symbols times their size.
	// Only those symbols from dysymtab.defsym are written into the debugging information.
	linkeditstringbase := linkeditsymbase + exeMacho.FileTOC.SymbolSize()*dysymtab.Nextdefsym

	// The first two bytes of the strings are reserved for space, null (' ', \000)
	linkeditstringcur := uint32(2)

	newsymtab.Syms = newsymtab.Syms[:0]
	newsymtab.Symoff = linkeditsymbase
	newsymtab.Stroff = linkeditstringbase
	newsymtab.Nsyms = dysymtab.Nextdefsym
	for i := uint32(0); i < dysymtab.Nextdefsym; i++ {
		ii := i + dysymtab.Iextdefsym
		oldsym := symtab.Syms[ii]
		newsymtab.Syms = append(newsymtab.Syms, oldsym)

		linkeditsyms = append(linkeditsyms, macho.Nlist64{Name: linkeditstringcur,
			Type: oldsym.Type, Sect: oldsym.Sect, Desc: oldsym.Desc, Value: oldsym.Value})
		linkeditstringcur += uint32(len(oldsym.Name)) + 1
		linkeditstrings = append(linkeditstrings, oldsym.Name)
	}
	newsymtab.Strsize = linkeditstringcur

	exeNeedsUuid := uuid == nil
	if exeNeedsUuid {
		uuid = &macho.Uuid{UuidCmd: macho.UuidCmd{LoadCmd: macho.LcUuid}}
		uuid.Len = uuid.LoadSize(newtoc)
		copy(uuid.Id[0:], contentuuid(&exeMacho.FileTOC)[0:16])
		uuid.Id[6] = uuid.Id[6]&^0xf0 | 0x40 // version 4 (pseudo-random); see section 4.1.3
		uuid.Id[8] = uuid.Id[8]&^0xc0 | 0x80 // variant bits; see section 4.1.1
	}
	newtoc.AddLoad(uuid)

	// For the specified segment (assumed to be in exeMacho) make a copy of its
	// sections with appropriate fields zeroed out, and append them to the
	// currently-last segment in newtoc.
	copyZOdSections := func(g *macho.Segment) {
		for i := g.Firstsect; i < g.Firstsect+g.Nsect; i++ {
			s := exeMacho.Sections[i].Copy()
			s.Offset = 0
			s.Reloff = 0
			s.Nreloc = 0
			newtoc.AddSection(s)
		}
	}

	newtoc.AddLoad(newsymtab)
	newtoc.AddSegment(pagezero)
	newtoc.AddSegment(newtext)
	copyZOdSections(text)
	newtoc.AddSegment(newdata)
	copyZOdSections(data)

	newlinkedit := linkedit.Copy()
	newlinkedit.Offset = uint64(linkeditsymbase)
	newlinkedit.Filesz = uint64(linkeditstringcur)
	newlinkedit.Addr = macho.RoundUp(newdata.Addr+newdata.Memsz, 1<<pageAlign) // Follows data sections in file
	newlinkedit.Memsz = macho.RoundUp(newlinkedit.Filesz, 1<<pageAlign)
	// The rest should copy over fine.
	newtoc.AddSegment(newlinkedit)

	dwarf := nonnilS("__DWARF")
	newdwarf := dwarf.CopyZeroed()
	newdwarf.Offset = macho.RoundUp(newlinkedit.Offset+newlinkedit.Filesz, 1<<pageAlign)
	newdwarf.Filesz = dwarf.UncompressedSize(&exeMacho.FileTOC, 1)
	newdwarf.Addr = newlinkedit.Addr + newlinkedit.Memsz // Follows linkedit sections in file.
	newdwarf.Memsz = macho.RoundUp(newdwarf.Filesz, 1<<pageAlign)
	newtoc.AddSegment(newdwarf)

	// Map out Dwarf sections (that is, this is section descriptors, not their contents).
	offset := uint32(newdwarf.Offset)
	for i := dwarf.Firstsect; i < dwarf.Firstsect+dwarf.Nsect; i++ {
		o := exeMacho.Sections[i]
		s := o.Copy()
		s.Offset = offset
		us := o.UncompressedSize()
		if s.Size < us {
			s.Size = uint64(us)
			s.Align = 0 // This is apparently true for debugging sections; not sure if it generalizes.
		}
		offset += uint32(us)
		if strings.HasPrefix(s.Name, "__z") {
			s.Name = "__" + s.Name[3:] // remove "z"
		}
		s.Reloff = 0
		s.Nreloc = 0
		newtoc.AddSection(s)
	}

	// Write segments/sections.
	// Only dwarf and linkedit contain anything interesting.

	// Memory map the output file to get the buffer directly.
	outDwarf := inputExe + ".dSYM/Contents/Resources/DWARF"
	if len(os.Args) > 2 {
		outDwarf = os.Args[2]
	} else {
		err := os.MkdirAll(outDwarf, 0755)
		if err != nil {
			fail("%v", err)
		}
		outDwarf = filepath.Join(outDwarf, filepath.Base(inputExe))
	}
	dwarfFile, buffer := CreateMmapFile(outDwarf, int64(newtoc.FileSize()))

	// (1) Linkedit segment
	// Symbol table
	offset = uint32(newlinkedit.Offset)
	for i := range linkeditsyms {
		if exeMacho.Magic == macho.Magic64 {
			offset += linkeditsyms[i].Put64(buffer[offset:], newtoc.ByteOrder)
		} else {
			offset += linkeditsyms[i].Put32(buffer[offset:], newtoc.ByteOrder)
		}
	}

	// Initial two bytes of string table, followed by actual zero-terminated strings.
	buffer[linkeditstringbase] = ' '
	buffer[linkeditstringbase+1] = 0
	offset = linkeditstringbase + 2
	for _, str := range linkeditstrings {
		for i := 0; i < len(str); i++ {
			buffer[offset] = str[i]
			offset++
		}
		buffer[offset] = 0
		offset++
	}

	// (2) DWARF segment
	ioff := newdwarf.Firstsect - dwarf.Firstsect
	for i := dwarf.Firstsect; i < dwarf.Firstsect+dwarf.Nsect; i++ {
		s := exeMacho.Sections[i]
		j := i + ioff
		s.PutUncompressedData(buffer[newtoc.Sections[j].Offset:])
	}

	// Because "text" overlaps the header and the loads, write them afterwards, just in case.
	// Write header.
	newtoc.Put(buffer)

	err = syscall.Munmap(buffer)
	if err != nil {
		fail("Munmap %s for dwarf output failed, %v", outDwarf, err)
	}
	err = dwarfFile.Close()
	if err != nil {
		fail("Close %s for dwarf output after mmap/munmap failed, %v", outDwarf, err)
	}

	if exeNeedsUuid { // Map the original exe, modify the header, and write the UUID command
		hdr := exeMacho.FileTOC.FileHeader
		oldCommandEnd := hdr.SizeCommands + newtoc.HdrSize()
		hdr.NCommands += 1
		hdr.SizeCommands += uuid.LoadSize(newtoc)

		mapf, err := os.OpenFile(inputExe, os.O_RDWR, 0)
		if err != nil {
			fail("Updating UUID in binary failed, %v", err)
		}
		exebuf, err := syscall.Mmap(int(mapf.Fd()), 0, int(macho.RoundUp(uint64(hdr.SizeCommands), 1<<pageAlign)),
			syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_FILE|syscall.MAP_SHARED)
		if err != nil {
			fail("Mmap of %s for UUID update failed, %v", inputExe, err)
		}
		_ = hdr.Put(exebuf, newtoc.ByteOrder)
		_ = uuid.Put(exebuf[oldCommandEnd:], newtoc.ByteOrder)
		err = syscall.Munmap(exebuf)
		if err != nil {
			fail("Munmap of %s for UUID update failed, %v", inputExe, err)
		}
	}
}

// CreateMmapFile creates the file 'outDwarf' of the specified size, mmaps that file,
// and returns the file descriptor and mapped buffer.
func CreateMmapFile(outDwarf string, size int64) (*os.File, []byte) {
	dwarfFile, err := os.OpenFile(outDwarf, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0666)
	if err != nil {
		fail("Open for mmap failed, %v", err)
	}
	err = os.Truncate(outDwarf, size)
	if err != nil {
		fail("Truncate/extend of %s to %d bytes failed, %v", dwarfFile, size, err)
	}
	buffer, err := syscall.Mmap(int(dwarfFile.Fd()), 0, int(size), syscall.PROT_READ|syscall.PROT_WRITE, syscall.MAP_FILE|syscall.MAP_SHARED)
	if err != nil {
		fail("Mmap %s for dwarf output update failed, %v", outDwarf, err)
	}
	return dwarfFile, buffer
}

// (dead code; retained for debugging)
func describe(exem *macho.FileTOC) {
	note("Type = %s, Flags=0x%x", exem.Type, uint32(exem.Flags))
	for i, l := range exem.Loads {
		if s, ok := l.(*macho.Segment); ok {
			fmt.Printf("Load %d is Segment %s, offset=0x%x, filesz=%d, addr=0x%x, memsz=%d, nsect=%d\n", i, s.Name,
				s.Offset, s.Filesz, s.Addr, s.Memsz, s.Nsect)
			for j := uint32(0); j < s.Nsect; j++ {
				c := exem.Sections[j+s.Firstsect]
				fmt.Printf("   Section %s, offset=0x%x, size=%d, addr=0x%x, flags=0x%x, nreloc=%d, res1=%d, res2=%d, res3=%d\n", c.Name, c.Offset, c.Size, c.Addr, c.Flags, c.Nreloc, c.Reserved1, c.Reserved2, c.Reserved3)
			}
		} else {
			fmt.Printf("Load %d is %v\n", i, l)
		}
	}
	if exem.SizeCommands != exem.LoadSize() {
		fail("recorded command size %d does not equal computed command size %d", exem.SizeCommands, exem.LoadSize())
	} else {
		note("recorded command size %d, computed command size %d", exem.SizeCommands, exem.LoadSize())
	}
	note("File size is %d", exem.FileSize())
}

// contentuuid returns a UUID derived from (some of) the content of an executable.
// specifically included are the non-DWARF sections, specifically excluded are things
// that surely depend on the presence or absence of DWARF sections (e.g., section
// numbers, positions with file, number of load commands).
// (It was considered desirable if this was insensitive to the presence of the
// __DWARF segment, however because it is not last, it moves other segments,
// whose contents appear to contain file offset references.)
func contentuuid(exem *macho.FileTOC) []byte {
	h := sha256.New()
	for _, l := range exem.Loads {
		if l.Command() == macho.LcUuid {
			continue
		}
		if s, ok := l.(*macho.Segment); ok {
			if s.Name == "__DWARF" || s.Name == "__PAGEZERO" {
				continue
			}
			for j := uint32(0); j < s.Nsect; j++ {
				c := exem.Sections[j+s.Firstsect]
				io.Copy(h, c.Open())
			}
		} // Getting dependence on other load commands right is fiddly.
	}
	return h.Sum(nil)
}


================================================
FILE: cmd/ssadump/main.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// ssadump: a tool for displaying and interpreting the SSA form of Go programs.
package main // import "golang.org/x/tools/cmd/ssadump"

import (
	"flag"
	"fmt"
	"go/build"
	"go/types"
	"os"
	"runtime"
	"runtime/pprof"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/interp"
	"golang.org/x/tools/go/ssa/ssautil"
)

// flags
var (
	mode = ssa.BuilderMode(0)

	testFlag = flag.Bool("test", false, "include implicit test packages and executables")

	runFlag = flag.Bool("run", false, "interpret the SSA program")

	interpFlag = flag.String("interp", "", `Options controlling the SSA test interpreter.
The value is a sequence of zero or more more of these letters:
R	disable [R]ecover() from panic; show interpreter crash instead.
T	[T]race execution of the program.  Best for single-threaded programs!
`)

	cpuprofile = flag.String("cpuprofile", "", "write cpu profile to file")

	args stringListValue

	tagsFlag = flag.String("tags", "", "comma-separated list of extra build tags (see: go help buildconstraint)")
)

func init() {
	flag.Var(&mode, "build", ssa.BuilderModeDoc)
	flag.Var(&args, "arg", "add argument to interpreted program")
}

const usage = `SSA builder and interpreter.
Usage: ssadump [-build=[DBCSNFLG]] [-test] [-run] [-interp=[TR]] [-arg=...] package...
Use -help flag to display options.

Examples:
% ssadump -build=F hello.go              # dump SSA form of a single package
% ssadump -build=F -test fmt             # dump SSA form of a package and its tests
% ssadump -run -interp=T hello.go        # interpret a program, with tracing

The -run flag causes ssadump to build the code in a runnable form and run the first
package named main.

Interpretation of the standard "testing" package is no longer supported.
`

func main() {
	if err := doMain(); err != nil {
		fmt.Fprintf(os.Stderr, "ssadump: %s\n", err)
		os.Exit(1)
	}
}

func doMain() error {
	flag.Parse()
	if len(flag.Args()) == 0 {
		fmt.Fprint(os.Stderr, usage)
		os.Exit(1)
	}

	cfg := &packages.Config{
		BuildFlags: []string{"-tags=" + *tagsFlag},
		Mode:       packages.LoadSyntax,
		Tests:      *testFlag,
	}

	// Choose types.Sizes from conf.Build.
	// TODO(adonovan): remove this when go/packages provides a better way.
	var wordSize int64 = 8
	switch build.Default.GOARCH {
	case "386", "arm":
		wordSize = 4
	}
	sizes := &types.StdSizes{
		MaxAlign: 8,
		WordSize: wordSize,
	}

	var interpMode interp.Mode
	for _, c := range *interpFlag {
		switch c {
		case 'T':
			interpMode |= interp.EnableTracing
		case 'R':
			interpMode |= interp.DisableRecover
		default:
			return fmt.Errorf("unknown -interp option: '%c'", c)
		}
	}

	// Profiling support.
	if *cpuprofile != "" {
		f, err := os.Create(*cpuprofile)
		if err != nil {
			fmt.Fprintln(os.Stderr, err)
			os.Exit(1)
		}
		pprof.StartCPUProfile(f)
		defer pprof.StopCPUProfile()
	}

	// Load, parse and type-check the initial packages,
	// and, if -run, their dependencies.
	if *runFlag {
		cfg.Mode = packages.LoadAllSyntax
	}
	initial, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		return err
	}
	if len(initial) == 0 {
		return fmt.Errorf("no packages")
	}
	if packages.PrintErrors(initial) > 0 {
		return fmt.Errorf("packages contain errors")
	}

	if !*runFlag {
		// Create (and display) SSA only for initial packages and wrappers.
		_, pkgs := ssautil.Packages(initial, mode)
		for i, p := range pkgs {
			if p == nil {
				return fmt.Errorf("cannot build SSA for package %s", initial[i])
			}
			p.Build()
		}

	} else {
		// Create SSA for initial packages and all dependencies, instantiating generics.
		mode |= ssa.InstantiateGenerics

		// TODO(adonovan): opt: use noreturn analysis over transitive
		// dependencies to prune spurious control flow graph edges.

		prog, pkgs := ssautil.AllPackages(initial, mode)
		for i, p := range pkgs {
			if p == nil {
				return fmt.Errorf("cannot build SSA for package %s", initial[i])
			}
		}

		// Run the interpreter.
		// Build SSA for all packages.
		prog.Build()

		// Earlier versions of the interpreter needed the runtime
		// package; however, interp cannot handle unsafe constructs
		// used during runtime's package initialization at the moment.
		// The key construct blocking support is:
		//    *((*T)(unsafe.Pointer(p)))
		// Unfortunately, this means only trivial programs can be
		// interpreted by ssadump.
		if prog.ImportedPackage("runtime") != nil {
			return fmt.Errorf("-run: program depends on runtime package (interpreter can run only trivial programs)")
		}

		if runtime.GOARCH != build.Default.GOARCH {
			return fmt.Errorf("cross-interpretation is not supported (target has GOARCH %s, interpreter has %s)",
				build.Default.GOARCH, runtime.GOARCH)
		}

		// Run first main package.
		for _, main := range ssautil.MainPackages(pkgs) {
			fmt.Fprintf(os.Stderr, "Running: %s\n", main.Pkg.Path())
			os.Exit(interp.Interpret(main, interpMode, sizes, main.Pkg.Path(), args))
		}
		return fmt.Errorf("no main package")
	}
	return nil
}

// stringListValue is a flag.Value that accumulates strings.
// e.g. --flag=one --flag=two would produce []string{"one", "two"}.
type stringListValue []string

func (ss *stringListValue) Get() any { return []string(*ss) }

func (ss *stringListValue) String() string { return fmt.Sprintf("%q", *ss) }

func (ss *stringListValue) Set(s string) error { *ss = append(*ss, s); return nil }


================================================
FILE: cmd/stress/stress.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build unix || aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || windows

// The stress utility is intended for catching sporadic failures.
// It runs a given process in parallel in a loop and collects any failures.
// Usage:
//
//	$ stress ./fmt.test -test.run=TestSometing -test.cpu=10
//
// You can also specify a number of parallel processes with -p flag;
// instruct the utility to not kill hanged processes for gdb attach;
// or specify the failure output you are looking for (if you want to
// ignore some other sporadic failures).
package main

import (
	"bytes"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"sync/atomic"
	"syscall"
	"time"
)

var (
	flagCount    = flag.Int("count", 0, "stop after `N` runs (default never stop)")
	flagFailfast = flag.Bool("failfast", false, "exit on first failure and write failure output to stderr")
	flagFailure  = flag.String("failure", "", "fail only if output matches `regexp`")
	flagIgnore   = flag.String("ignore", "", "ignore failure if output matches `regexp`")
	flagKill     = flag.Bool("kill", true, "kill timed out processes if true, otherwise just print pid (to attach with gdb)")
	flagOutput   = flag.String("o", defaultPrefix(), "output failure logs to `path` plus a unique suffix")
	flagP        = flag.Int("p", runtime.NumCPU(), "run `N` processes in parallel")
	flagTimeout  = flag.Duration("timeout", 10*time.Minute, "timeout each process after `duration`")
)

func init() {
	flag.Usage = func() {
		os.Stderr.WriteString(`The stress utility is intended for catching sporadic failures.
It runs a given process in parallel in a loop and collects any failures.
Usage:

	$ stress ./fmt.test -test.run=TestSometing -test.cpu=10

`)
		flag.PrintDefaults()
	}
}

func defaultPrefix() string {
	date := time.Now().Format("go-stress-20060102T150405-")
	return filepath.Join(os.TempDir(), date)
}

func main() {
	flag.Parse()
	if *flagP <= 0 || *flagTimeout <= 0 || len(flag.Args()) == 0 {
		flag.Usage()
		os.Exit(1)
	}
	var failureRe, ignoreRe *regexp.Regexp
	if *flagFailure != "" {
		var err error
		if failureRe, err = regexp.Compile(*flagFailure); err != nil {
			fmt.Println("bad failure regexp:", err)
			os.Exit(1)
		}
	}
	if *flagIgnore != "" {
		var err error
		if ignoreRe, err = regexp.Compile(*flagIgnore); err != nil {
			fmt.Println("bad ignore regexp:", err)
			os.Exit(1)
		}
	}
	res := make(chan []byte)
	var started atomic.Int64
	for i := 0; i < *flagP; i++ {
		go func() {
			for {
				// Note: Must started.Add(1) even if not using -count,
				// because it enables the '%d active' print below.
				if started.Add(1) > int64(*flagCount) && *flagCount > 0 {
					break
				}
				cmd := exec.Command(flag.Args()[0], flag.Args()[1:]...)
				var buf bytes.Buffer
				cmd.Stdout = &buf
				cmd.Stderr = &buf
				err := cmd.Start() // make cmd.Process valid for timeout goroutine
				done := make(chan bool)
				if err == nil && *flagTimeout > 0 {
					go func() {
						select {
						case <-done:
							return
						case <-time.After(*flagTimeout):
						}
						if !*flagKill {
							fmt.Printf("process %v timed out\n", cmd.Process.Pid)
							return
						}
						cmd.Process.Signal(syscall.SIGABRT)
						select {
						case <-done:
							return
						case <-time.After(10 * time.Second):
						}
						cmd.Process.Kill()
					}()
				}
				if err == nil {
					err = cmd.Wait()
				}
				out := buf.Bytes()
				close(done)
				if err != nil && (failureRe == nil || failureRe.Match(out)) && (ignoreRe == nil || !ignoreRe.Match(out)) {
					out = append(out, fmt.Sprintf("\n\nERROR: %v\n", err)...)
				} else {
					out = []byte{}
				}
				res <- out
			}
		}()
	}
	runs, fails := 0, 0
	start := time.Now()
	ticker := time.NewTicker(5 * time.Second).C
	status := func(context string) {
		elapsed := time.Since(start).Truncate(time.Second)
		var pct string
		if fails > 0 {
			pct = fmt.Sprintf(" (%0.2f%%)", 100.0*float64(fails)/float64(runs))
		}
		var active string
		n := started.Load() - int64(runs)
		if *flagCount > 0 {
			// started counts past *flagCount at end; do not count those
			// TODO: n = min(n, int64(*flagCount-runs))
			if x := int64(*flagCount - runs); n > x {
				n = x
			}
		}
		if n > 0 {
			active = fmt.Sprintf(", %d active", n)
		}
		fmt.Printf("%v: %v runs %s, %v failures%s%s\n", elapsed, runs, context, fails, pct, active)
	}
	for {
		select {
		case out := <-res:
			runs++
			if len(out) > 0 {
				fails++
				if *flagFailfast {
					os.Stderr.Write(out)
					os.Exit(1)
				}
				dir, path := filepath.Split(*flagOutput)
				f, err := os.CreateTemp(dir, path)
				if err != nil {
					fmt.Printf("failed to create temp file: %v\n", err)
					os.Exit(1)
				}
				f.Write(out)
				f.Close()
				if len(out) > 2<<10 {
					out := out[:2<<10]
					fmt.Printf("\n%s\n%s\n…\n", f.Name(), out)
				} else {
					fmt.Printf("\n%s\n%s\n", f.Name(), out)
				}
			}
			if *flagCount > 0 && runs >= *flagCount {
				status("total")
				if fails > 0 {
					os.Exit(1)
				}
				os.Exit(0)
			}
		case <-ticker:
			status("so far")
		}
	}
}


================================================
FILE: cmd/stringer/endtoend_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go command is not available on android

//go:build !android

package main

import (
	"bytes"
	"flag"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"slices"
	"strings"
	"sync"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

// This file contains a test that compiles and runs each program in testdata
// after generating the string method for its type. The rule is that for testdata/x.go
// we run stringer -type X and then compile and run the program. The resulting
// binary panics if the String method for X is not correct, including for error cases.

func TestMain(m *testing.M) {
	if os.Getenv("STRINGER_TEST_IS_STRINGER") != "" {
		main()
		os.Exit(0)
	}

	// Inform subprocesses that they should run the cmd/stringer main instead of
	// running tests. It's a close approximation to building and running the real
	// command, and much less complicated and expensive to build and clean up.
	os.Setenv("STRINGER_TEST_IS_STRINGER", "1")

	flag.Parse()
	if testing.Verbose() {
		os.Setenv("GOPACKAGESDEBUG", "true")
	}

	os.Exit(m.Run())
}

func TestEndToEnd(t *testing.T) {
	testenv.NeedsTool(t, "go")

	stringer := stringerPath(t)
	// Read the testdata directory.
	fd, err := os.Open("testdata")
	if err != nil {
		t.Fatal(err)
	}
	defer fd.Close()
	names, err := fd.Readdirnames(-1)
	if err != nil {
		t.Fatalf("Readdirnames: %s", err)
	}
	// Generate, compile, and run the test programs.
	for _, name := range names {
		if name == "typeparams" {
			// ignore the directory containing the tests with type params
			continue
		}
		if !strings.HasSuffix(name, ".go") {
			t.Errorf("%s is not a Go file", name)
			continue
		}
		if strings.HasPrefix(name, "tag_") || strings.HasPrefix(name, "vary_") {
			// This file is used for tag processing in TestTags or TestConstValueChange, below.
			continue
		}
		t.Run(name, func(t *testing.T) {
			if name == "cgo.go" {
				testenv.NeedsTool(t, "cgo")
			}
			stringerCompileAndRun(t, t.TempDir(), stringer, typeName(name), name)
		})
	}
}

// a type name for stringer. use the last component of the file name with the .go
func typeName(fname string) string {
	// file names are known to be ascii and end .go
	base := path.Base(fname)
	return fmt.Sprintf("%c%s", base[0]+'A'-'a', base[1:len(base)-len(".go")])
}

// TestTags verifies that the -tags flag works as advertised.
func TestTags(t *testing.T) {
	stringer := stringerPath(t)
	dir := t.TempDir()
	var (
		protectedConst = []byte("TagProtected")
		output         = filepath.Join(dir, "const_string.go")
	)
	for _, file := range []string{"tag_main.go", "tag_tag.go"} {
		err := copy(filepath.Join(dir, file), filepath.Join("testdata", file))
		if err != nil {
			t.Fatal(err)
		}
	}
	// Run stringer in the directory that contains the module that contains the package files.
	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module test\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	err := runInDir(t, dir, stringer, "-type", "Const", ".")
	if err != nil {
		t.Fatal(err)
	}
	result, err := os.ReadFile(output)
	if err != nil {
		t.Fatal(err)
	}
	if bytes.Contains(result, protectedConst) {
		t.Fatal("tagged variable appears in untagged run")
	}
	err = os.Remove(output)
	if err != nil {
		t.Fatal(err)
	}
	err = runInDir(t, dir, stringer, "-type", "Const", "-tags", "tag", ".")
	if err != nil {
		t.Fatal(err)
	}
	result, err = os.ReadFile(output)
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Contains(result, protectedConst) {
		t.Fatal("tagged variable does not appear in tagged run")
	}
}

// TestConstValueChange verifies that if a constant value changes and
// the stringer code is not regenerated, we'll get a compiler error.
func TestConstValueChange(t *testing.T) {
	testenv.NeedsTool(t, "go")

	stringer := stringerPath(t)
	dir := t.TempDir()
	source := filepath.Join(dir, "day.go")
	err := copy(source, filepath.Join("testdata", "day.go"))
	if err != nil {
		t.Fatal(err)
	}
	stringSource := filepath.Join(dir, "day_string.go")
	// Run stringer in the directory that contains the module that contains the package files.
	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module test\n"), 0o600); err != nil {
		t.Fatal(err)
	}
	err = runInDir(t, dir, stringer, "-type", "Day", "-output", stringSource)
	if err != nil {
		t.Fatal(err)
	}
	// Run the binary in the temporary directory as a sanity check.
	err = run(t, "go", "run", stringSource, source)
	if err != nil {
		t.Fatal(err)
	}
	// Overwrite the source file with a version that has changed constants.
	err = copy(source, filepath.Join("testdata", "vary_day.go"))
	if err != nil {
		t.Fatal(err)
	}
	// Unfortunately different compilers may give different error messages,
	// so there's no easy way to verify that the build failed specifically
	// because the constants changed rather than because the vary_day.go
	// file is invalid.
	//
	// Instead we'll just rely on manual inspection of the polluted test
	// output. An alternative might be to check that the error output
	// matches a set of possible error strings emitted by known
	// Go compilers.
	t.Logf("Note: the following messages should indicate an out-of-bounds compiler error\n")
	err = run(t, "go", "build", stringSource, source)
	if err == nil {
		t.Fatal("unexpected compiler success")
	}
}

var testfileSrcs = map[string]string{
	"go.mod": "module foo",

	// Normal file in the package.
	"main.go": `package foo

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)
`,

	// Test file in the package.
	"main_test.go": `package foo

type Bar int

const (
	barX Bar = iota
	barY
	barZ
)
`,

	// Test file in the test package.
	"main_pkg_test.go": `package foo_test

type Baz int

const (
	bazX Baz = iota
	bazY
	bazZ
)
`,
}

// Test stringer on types defined in different kinds of tests.
// The generated code should not interfere between itself.
func TestTestFiles(t *testing.T) {
	testenv.NeedsTool(t, "go")
	stringer := stringerPath(t)

	dir := t.TempDir()
	t.Logf("TestTestFiles in: %s \n", dir)
	for name, src := range testfileSrcs {
		source := filepath.Join(dir, name)
		err := os.WriteFile(source, []byte(src), 0666)
		if err != nil {
			t.Fatalf("write file: %s", err)
		}
	}

	// Must run stringer in the temp directory, see TestTags.
	err := runInDir(t, dir, stringer, "-type=Foo,Bar,Baz", dir)
	if err != nil {
		t.Fatalf("run stringer: %s", err)
	}

	// Check that stringer has created the expected files.
	content, err := os.ReadDir(dir)
	if err != nil {
		t.Fatalf("read dir: %s", err)
	}
	gotFiles := []string{}
	for _, f := range content {
		if !f.IsDir() {
			gotFiles = append(gotFiles, f.Name())
		}
	}
	wantFiles := []string{
		// Original.
		"go.mod",
		"main.go",
		"main_test.go",
		"main_pkg_test.go",
		// Generated.
		"foo_string.go",
		"bar_string_test.go",
		"baz_string_test.go",
	}
	slices.Sort(gotFiles)
	slices.Sort(wantFiles)
	if !reflect.DeepEqual(gotFiles, wantFiles) {
		t.Errorf("stringer generated files:\n%s\n\nbut want:\n%s",
			strings.Join(gotFiles, "\n"),
			strings.Join(wantFiles, "\n"),
		)
	}

	// Run go test as a smoke test.
	err = runInDir(t, dir, "go", "test", "-count=1", ".")
	if err != nil {
		t.Fatalf("go test: %s", err)
	}
}

// The -output flag cannot be used in combination with matching types across multiple packages.
func TestCollidingOutput(t *testing.T) {
	testenv.NeedsTool(t, "go")
	stringer := stringerPath(t)

	dir := t.TempDir()
	for name, src := range testfileSrcs {
		source := filepath.Join(dir, name)
		err := os.WriteFile(source, []byte(src), 0666)
		if err != nil {
			t.Fatalf("write file: %s", err)
		}
	}

	// Must run stringer in the temp directory, see TestTags.
	err := runInDir(t, dir, stringer, "-type=Foo,Bar,Baz", "-output=somefile.go", dir)
	if err == nil {
		t.Fatal("unexpected stringer success")
	}
}

var exe struct {
	path string
	err  error
	once sync.Once
}

func stringerPath(t *testing.T) string {
	testenv.NeedsExec(t)

	exe.once.Do(func() {
		exe.path, exe.err = os.Executable()
	})
	if exe.err != nil {
		t.Fatal(exe.err)
	}
	return exe.path
}

// stringerCompileAndRun runs stringer for the named file and compiles and
// runs the target binary in directory dir. That binary will panic if the String method is incorrect.
func stringerCompileAndRun(t *testing.T, dir, stringer, typeName, fileName string) {
	t.Logf("run: %s %s\n", fileName, typeName)
	source := filepath.Join(dir, path.Base(fileName))
	err := copy(source, filepath.Join("testdata", fileName))
	if err != nil {
		t.Fatalf("copying file to temporary directory: %s", err)
	}
	stringSource := filepath.Join(dir, typeName+"_string.go")
	// Run stringer in temporary directory.
	err = run(t, stringer, "-type", typeName, "-output", stringSource, source)
	if err != nil {
		t.Fatal(err)
	}
	// Run the binary in the temporary directory.
	err = run(t, "go", "run", stringSource, source)
	if err != nil {
		t.Fatal(err)
	}
}

// copy copies the from file to the to file.
func copy(to, from string) error {
	toFd, err := os.Create(to)
	if err != nil {
		return err
	}
	defer toFd.Close()
	fromFd, err := os.Open(from)
	if err != nil {
		return err
	}
	defer fromFd.Close()
	_, err = io.Copy(toFd, fromFd)
	return err
}

// run runs a single command and returns an error if it does not succeed.
// os/exec should have this function, to be honest.
func run(t testing.TB, name string, arg ...string) error {
	t.Helper()
	return runInDir(t, ".", name, arg...)
}

// runInDir runs a single command in directory dir and returns an error if
// it does not succeed.
func runInDir(t testing.TB, dir, name string, arg ...string) error {
	t.Helper()
	cmd := testenv.Command(t, name, arg...)
	cmd.Dir = dir
	out, err := cmd.CombinedOutput()
	if len(out) > 0 {
		t.Logf("%s", out)
	}
	if err != nil {
		return fmt.Errorf("%v: %v", cmd, err)
	}
	return nil
}


================================================
FILE: cmd/stringer/golden_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains simple golden tests for various examples.
// Besides validating the results when the implementation changes,
// it provides a way to look at the generated code without having
// to execute the print statements in one's head.

package main

import (
	"os"
	"path/filepath"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

// Golden represents a test case.
type Golden struct {
	name        string
	trimPrefix  string
	lineComment bool
	input       string // input; the package clause is provided when running the test.
	output      string // expected output.
}

var golden = []Golden{
	{"day", "", false, day_in, day_out},
	{"offset", "", false, offset_in, offset_out},
	{"gap", "", false, gap_in, gap_out},
	{"num", "", false, num_in, num_out},
	{"unum", "", false, unum_in, unum_out},
	{"unumpos", "", false, unumpos_in, unumpos_out},
	{"prime", "", false, prime_in, prime_out},
	{"prefix", "Type", false, prefix_in, prefix_out},
	{"tokens", "", true, tokens_in, tokens_out},
	{"overflow8", "", false, overflow8_in, overflow8_out},
}

// Each example starts with "type XXX [u]int", with a single space separating them.

// Simple test: enumeration of type int starting at 0.
const day_in = `type Day int
const (
	Monday Day = iota
	Tuesday
	Wednesday
	Thursday
	Friday
	Saturday
	Sunday
)
`

const day_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[Monday-0]
	_ = x[Tuesday-1]
	_ = x[Wednesday-2]
	_ = x[Thursday-3]
	_ = x[Friday-4]
	_ = x[Saturday-5]
	_ = x[Sunday-6]
}

const _Day_name = "MondayTuesdayWednesdayThursdayFridaySaturdaySunday"

var _Day_index = [...]uint8{0, 6, 13, 22, 30, 36, 44, 50}

func (i Day) String() string {
	idx := int(i) - 0
	if i < 0 || idx >= len(_Day_index)-1 {
		return "Day(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Day_name[_Day_index[idx]:_Day_index[idx+1]]
}
`

// Enumeration with an offset.
// Also includes a duplicate.
const offset_in = `type Number int
const (
	_ Number = iota
	One
	Two
	Three
	AnotherOne = One  // Duplicate; note that AnotherOne doesn't appear below.
)
`

const offset_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[One-1]
	_ = x[Two-2]
	_ = x[Three-3]
}

const _Number_name = "OneTwoThree"

var _Number_index = [...]uint8{0, 3, 6, 11}

func (i Number) String() string {
	idx := int(i) - 1
	if i < 1 || idx >= len(_Number_index)-1 {
		return "Number(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Number_name[_Number_index[idx]:_Number_index[idx+1]]
}
`

// Gaps and an offset.
const gap_in = `type Gap int
const (
	Two Gap = 2
	Three Gap = 3
	Five Gap = 5
	Six Gap = 6
	Seven Gap = 7
	Eight Gap = 8
	Nine Gap = 9
	Eleven Gap = 11
)
`

const gap_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[Two-2]
	_ = x[Three-3]
	_ = x[Five-5]
	_ = x[Six-6]
	_ = x[Seven-7]
	_ = x[Eight-8]
	_ = x[Nine-9]
	_ = x[Eleven-11]
}

const (
	_Gap_name_0 = "TwoThree"
	_Gap_name_1 = "FiveSixSevenEightNine"
	_Gap_name_2 = "Eleven"
)

var (
	_Gap_index_0 = [...]uint8{0, 3, 8}
	_Gap_index_1 = [...]uint8{0, 4, 7, 12, 17, 21}
)

func (i Gap) String() string {
	switch {
	case 2 <= i && i <= 3:
		i -= 2
		return _Gap_name_0[_Gap_index_0[i]:_Gap_index_0[i+1]]
	case 5 <= i && i <= 9:
		i -= 5
		return _Gap_name_1[_Gap_index_1[i]:_Gap_index_1[i+1]]
	case i == 11:
		return _Gap_name_2
	default:
		return "Gap(" + strconv.FormatInt(int64(i), 10) + ")"
	}
}
`

// Signed integers spanning zero.
const num_in = `type Num int
const (
	m_2 Num = -2 + iota
	m_1
	m0
	m1
	m2
)
`

const num_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[m_2 - -2]
	_ = x[m_1 - -1]
	_ = x[m0-0]
	_ = x[m1-1]
	_ = x[m2-2]
}

const _Num_name = "m_2m_1m0m1m2"

var _Num_index = [...]uint8{0, 3, 6, 8, 10, 12}

func (i Num) String() string {
	idx := int(i) - -2
	if i < -2 || idx >= len(_Num_index)-1 {
		return "Num(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Num_name[_Num_index[idx]:_Num_index[idx+1]]
}
`

// Unsigned integers spanning zero.
const unum_in = `type Unum uint
const (
	m_2 Unum = iota + 253
	m_1
)

const (
	m0 Unum = iota
	m1
	m2
)
`

const unum_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[m_2-253]
	_ = x[m_1-254]
	_ = x[m0-0]
	_ = x[m1-1]
	_ = x[m2-2]
}

const (
	_Unum_name_0 = "m0m1m2"
	_Unum_name_1 = "m_2m_1"
)

var (
	_Unum_index_0 = [...]uint8{0, 2, 4, 6}
	_Unum_index_1 = [...]uint8{0, 3, 6}
)

func (i Unum) String() string {
	switch {
	case i <= 2:
		return _Unum_name_0[_Unum_index_0[i]:_Unum_index_0[i+1]]
	case 253 <= i && i <= 254:
		i -= 253
		return _Unum_name_1[_Unum_index_1[i]:_Unum_index_1[i+1]]
	default:
		return "Unum(" + strconv.FormatInt(int64(i), 10) + ")"
	}
}
`

// Unsigned positive integers.
const unumpos_in = `type Unumpos uint
const (
	m253 Unumpos = iota + 253
	m254
)

const (
	m1 Unumpos = iota + 1
	m2
	m3
)
`

const unumpos_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[m253-253]
	_ = x[m254-254]
	_ = x[m1-1]
	_ = x[m2-2]
	_ = x[m3-3]
}

const (
	_Unumpos_name_0 = "m1m2m3"
	_Unumpos_name_1 = "m253m254"
)

var (
	_Unumpos_index_0 = [...]uint8{0, 2, 4, 6}
	_Unumpos_index_1 = [...]uint8{0, 4, 8}
)

func (i Unumpos) String() string {
	switch {
	case 1 <= i && i <= 3:
		i -= 1
		return _Unumpos_name_0[_Unumpos_index_0[i]:_Unumpos_index_0[i+1]]
	case 253 <= i && i <= 254:
		i -= 253
		return _Unumpos_name_1[_Unumpos_index_1[i]:_Unumpos_index_1[i+1]]
	default:
		return "Unumpos(" + strconv.FormatInt(int64(i), 10) + ")"
	}
}
`

// Enough gaps to trigger a map implementation of the method.
// Also includes a duplicate to test that it doesn't cause problems
const prime_in = `type Prime int
const (
	p2 Prime = 2
	p3 Prime = 3
	p5 Prime = 5
	p7 Prime = 7
	p77 Prime = 7 // Duplicate; note that p77 doesn't appear below.
	p11 Prime = 11
	p13 Prime = 13
	p17 Prime = 17
	p19 Prime = 19
	p23 Prime = 23
	p29 Prime = 29
	p37 Prime = 31
	p41 Prime = 41
	p43 Prime = 43
)
`

const prime_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[p2-2]
	_ = x[p3-3]
	_ = x[p5-5]
	_ = x[p7-7]
	_ = x[p77-7]
	_ = x[p11-11]
	_ = x[p13-13]
	_ = x[p17-17]
	_ = x[p19-19]
	_ = x[p23-23]
	_ = x[p29-29]
	_ = x[p37-31]
	_ = x[p41-41]
	_ = x[p43-43]
}

const _Prime_name = "p2p3p5p7p11p13p17p19p23p29p37p41p43"

var _Prime_map = map[Prime]string{
	2:  _Prime_name[0:2],
	3:  _Prime_name[2:4],
	5:  _Prime_name[4:6],
	7:  _Prime_name[6:8],
	11: _Prime_name[8:11],
	13: _Prime_name[11:14],
	17: _Prime_name[14:17],
	19: _Prime_name[17:20],
	23: _Prime_name[20:23],
	29: _Prime_name[23:26],
	31: _Prime_name[26:29],
	41: _Prime_name[29:32],
	43: _Prime_name[32:35],
}

func (i Prime) String() string {
	if str, ok := _Prime_map[i]; ok {
		return str
	}
	return "Prime(" + strconv.FormatInt(int64(i), 10) + ")"
}
`

const prefix_in = `type Type int
const (
	TypeInt Type = iota
	TypeString
	TypeFloat
	TypeRune
	TypeByte
	TypeStruct
	TypeSlice
)
`

const prefix_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[TypeInt-0]
	_ = x[TypeString-1]
	_ = x[TypeFloat-2]
	_ = x[TypeRune-3]
	_ = x[TypeByte-4]
	_ = x[TypeStruct-5]
	_ = x[TypeSlice-6]
}

const _Type_name = "IntStringFloatRuneByteStructSlice"

var _Type_index = [...]uint8{0, 3, 9, 14, 18, 22, 28, 33}

func (i Type) String() string {
	idx := int(i) - 0
	if i < 0 || idx >= len(_Type_index)-1 {
		return "Type(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Type_name[_Type_index[idx]:_Type_index[idx+1]]
}
`

const tokens_in = `type Token int
const (
	And Token = iota // &
	Or               // |
	Add              // +
	Sub              // -
	Ident
	Period // .

	// not to be used
	SingleBefore
	// not to be used
	BeforeAndInline // inline
	InlineGeneral /* inline general */
)
`

const tokens_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[And-0]
	_ = x[Or-1]
	_ = x[Add-2]
	_ = x[Sub-3]
	_ = x[Ident-4]
	_ = x[Period-5]
	_ = x[SingleBefore-6]
	_ = x[BeforeAndInline-7]
	_ = x[InlineGeneral-8]
}

const _Token_name = "&|+-Ident.SingleBeforeinlineinline general"

var _Token_index = [...]uint8{0, 1, 2, 3, 4, 9, 10, 22, 28, 42}

func (i Token) String() string {
	idx := int(i) - 0
	if i < 0 || idx >= len(_Token_index)-1 {
		return "Token(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Token_name[_Token_index[idx]:_Token_index[idx+1]]
}
`

const overflow8_in = `type Overflow8 int8
const (
	O_128 Overflow8 = -128
	O_127 Overflow8 = -127
	O_126 Overflow8 = -126
	O_125 Overflow8 = -125
	O_124 Overflow8 = -124
	O_123 Overflow8 = -123
	O_122 Overflow8 = -122
	O_121 Overflow8 = -121
	O_120 Overflow8 = -120
	O_119 Overflow8 = -119
	O_118 Overflow8 = -118
	O_117 Overflow8 = -117
	O_116 Overflow8 = -116
	O_115 Overflow8 = -115
	O_114 Overflow8 = -114
	O_113 Overflow8 = -113
	O_112 Overflow8 = -112
	O_111 Overflow8 = -111
	O_110 Overflow8 = -110
	O_109 Overflow8 = -109
	O_108 Overflow8 = -108
	O_107 Overflow8 = -107
	O_106 Overflow8 = -106
	O_105 Overflow8 = -105
	O_104 Overflow8 = -104
	O_103 Overflow8 = -103
	O_102 Overflow8 = -102
	O_101 Overflow8 = -101
	O_100 Overflow8 = -100
	O_99 Overflow8 = -99
	O_98 Overflow8 = -98
	O_97 Overflow8 = -97
	O_96 Overflow8 = -96
	O_95 Overflow8 = -95
	O_94 Overflow8 = -94
	O_93 Overflow8 = -93
	O_92 Overflow8 = -92
	O_91 Overflow8 = -91
	O_90 Overflow8 = -90
	O_89 Overflow8 = -89
	O_88 Overflow8 = -88
	O_87 Overflow8 = -87
	O_86 Overflow8 = -86
	O_85 Overflow8 = -85
	O_84 Overflow8 = -84
	O_83 Overflow8 = -83
	O_82 Overflow8 = -82
	O_81 Overflow8 = -81
	O_80 Overflow8 = -80
	O_79 Overflow8 = -79
	O_78 Overflow8 = -78
	O_77 Overflow8 = -77
	O_76 Overflow8 = -76
	O_75 Overflow8 = -75
	O_74 Overflow8 = -74
	O_73 Overflow8 = -73
	O_72 Overflow8 = -72
	O_71 Overflow8 = -71
	O_70 Overflow8 = -70
	O_69 Overflow8 = -69
	O_68 Overflow8 = -68
	O_67 Overflow8 = -67
	O_66 Overflow8 = -66
	O_65 Overflow8 = -65
	O_64 Overflow8 = -64
	O_63 Overflow8 = -63
	O_62 Overflow8 = -62
	O_61 Overflow8 = -61
	O_60 Overflow8 = -60
	O_59 Overflow8 = -59
	O_58 Overflow8 = -58
	O_57 Overflow8 = -57
	O_56 Overflow8 = -56
	O_55 Overflow8 = -55
	O_54 Overflow8 = -54
	O_53 Overflow8 = -53
	O_52 Overflow8 = -52
	O_51 Overflow8 = -51
	O_50 Overflow8 = -50
	O_49 Overflow8 = -49
	O_48 Overflow8 = -48
	O_47 Overflow8 = -47
	O_46 Overflow8 = -46
	O_45 Overflow8 = -45
	O_44 Overflow8 = -44
	O_43 Overflow8 = -43
	O_42 Overflow8 = -42
	O_41 Overflow8 = -41
	O_40 Overflow8 = -40
	O_39 Overflow8 = -39
	O_38 Overflow8 = -38
	O_37 Overflow8 = -37
	O_36 Overflow8 = -36
	O_35 Overflow8 = -35
	O_34 Overflow8 = -34
	O_33 Overflow8 = -33
	O_32 Overflow8 = -32
	O_31 Overflow8 = -31
	O_30 Overflow8 = -30
	O_29 Overflow8 = -29
	O_28 Overflow8 = -28
	O_27 Overflow8 = -27
	O_26 Overflow8 = -26
	O_25 Overflow8 = -25
	O_24 Overflow8 = -24
	O_23 Overflow8 = -23
	O_22 Overflow8 = -22
	O_21 Overflow8 = -21
	O_20 Overflow8 = -20
	O_19 Overflow8 = -19
	O_18 Overflow8 = -18
	O_17 Overflow8 = -17
	O_16 Overflow8 = -16
	O_15 Overflow8 = -15
	O_14 Overflow8 = -14
	O_13 Overflow8 = -13
	O_12 Overflow8 = -12
	O_11 Overflow8 = -11
	O_10 Overflow8 = -10
	O_9 Overflow8 = -9
	O_8 Overflow8 = -8
	O_7 Overflow8 = -7
	O_6 Overflow8 = -6
	O_5 Overflow8 = -5
	O_4 Overflow8 = -4
	O_3 Overflow8 = -3
	O_2 Overflow8 = -2
	O_1 Overflow8 = -1
	O0 Overflow8 = 0
	O1 Overflow8 = 1
	O2 Overflow8 = 2
	O3 Overflow8 = 3
	O4 Overflow8 = 4
	O5 Overflow8 = 5
	O6 Overflow8 = 6
	O7 Overflow8 = 7
	O8 Overflow8 = 8
	O9 Overflow8 = 9
	O10 Overflow8 = 10
	O11 Overflow8 = 11
	O12 Overflow8 = 12
	O13 Overflow8 = 13
	O14 Overflow8 = 14
	O15 Overflow8 = 15
	O16 Overflow8 = 16
	O17 Overflow8 = 17
	O18 Overflow8 = 18
	O19 Overflow8 = 19
	O20 Overflow8 = 20
	O21 Overflow8 = 21
	O22 Overflow8 = 22
	O23 Overflow8 = 23
	O24 Overflow8 = 24
	O25 Overflow8 = 25
	O26 Overflow8 = 26
	O27 Overflow8 = 27
	O28 Overflow8 = 28
	O29 Overflow8 = 29
	O30 Overflow8 = 30
	O31 Overflow8 = 31
	O32 Overflow8 = 32
	O33 Overflow8 = 33
	O34 Overflow8 = 34
	O35 Overflow8 = 35
	O36 Overflow8 = 36
	O37 Overflow8 = 37
	O38 Overflow8 = 38
	O39 Overflow8 = 39
	O40 Overflow8 = 40
	O41 Overflow8 = 41
	O42 Overflow8 = 42
	O43 Overflow8 = 43
	O44 Overflow8 = 44
	O45 Overflow8 = 45
	O46 Overflow8 = 46
	O47 Overflow8 = 47
	O48 Overflow8 = 48
	O49 Overflow8 = 49
	O50 Overflow8 = 50
	O51 Overflow8 = 51
	O52 Overflow8 = 52
	O53 Overflow8 = 53
	O54 Overflow8 = 54
	O55 Overflow8 = 55
	O56 Overflow8 = 56
	O57 Overflow8 = 57
	O58 Overflow8 = 58
	O59 Overflow8 = 59
	O60 Overflow8 = 60
	O61 Overflow8 = 61
	O62 Overflow8 = 62
	O63 Overflow8 = 63
	O64 Overflow8 = 64
	O65 Overflow8 = 65
	O66 Overflow8 = 66
	O67 Overflow8 = 67
	O68 Overflow8 = 68
	O69 Overflow8 = 69
	O70 Overflow8 = 70
	O71 Overflow8 = 71
	O72 Overflow8 = 72
	O73 Overflow8 = 73
	O74 Overflow8 = 74
	O75 Overflow8 = 75
	O76 Overflow8 = 76
	O77 Overflow8 = 77
	O78 Overflow8 = 78
	O79 Overflow8 = 79
	O80 Overflow8 = 80
	O81 Overflow8 = 81
	O82 Overflow8 = 82
	O83 Overflow8 = 83
	O84 Overflow8 = 84
	O85 Overflow8 = 85
	O86 Overflow8 = 86
	O87 Overflow8 = 87
	O88 Overflow8 = 88
	O89 Overflow8 = 89
	O90 Overflow8 = 90
	O91 Overflow8 = 91
	O92 Overflow8 = 92
	O93 Overflow8 = 93
	O94 Overflow8 = 94
	O95 Overflow8 = 95
	O96 Overflow8 = 96
	O97 Overflow8 = 97
	O98 Overflow8 = 98
	O99 Overflow8 = 99
	O100 Overflow8 = 100
	O101 Overflow8 = 101
	O102 Overflow8 = 102
	O103 Overflow8 = 103
	O104 Overflow8 = 104
	O105 Overflow8 = 105
	O106 Overflow8 = 106
	O107 Overflow8 = 107
	O108 Overflow8 = 108
	O109 Overflow8 = 109
	O110 Overflow8 = 110
	O111 Overflow8 = 111
	O112 Overflow8 = 112
	O113 Overflow8 = 113
	O114 Overflow8 = 114
	O115 Overflow8 = 115
	O116 Overflow8 = 116
	O117 Overflow8 = 117
	O118 Overflow8 = 118
	O119 Overflow8 = 119
	O120 Overflow8 = 120
	O121 Overflow8 = 121
	O122 Overflow8 = 122
	O123 Overflow8 = 123
	O124 Overflow8 = 124
	O125 Overflow8 = 125
	O126 Overflow8 = 126
	O127 Overflow8 = 127
)
`

const overflow8_out = `func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[O_128 - -128]
	_ = x[O_127 - -127]
	_ = x[O_126 - -126]
	_ = x[O_125 - -125]
	_ = x[O_124 - -124]
	_ = x[O_123 - -123]
	_ = x[O_122 - -122]
	_ = x[O_121 - -121]
	_ = x[O_120 - -120]
	_ = x[O_119 - -119]
	_ = x[O_118 - -118]
	_ = x[O_117 - -117]
	_ = x[O_116 - -116]
	_ = x[O_115 - -115]
	_ = x[O_114 - -114]
	_ = x[O_113 - -113]
	_ = x[O_112 - -112]
	_ = x[O_111 - -111]
	_ = x[O_110 - -110]
	_ = x[O_109 - -109]
	_ = x[O_108 - -108]
	_ = x[O_107 - -107]
	_ = x[O_106 - -106]
	_ = x[O_105 - -105]
	_ = x[O_104 - -104]
	_ = x[O_103 - -103]
	_ = x[O_102 - -102]
	_ = x[O_101 - -101]
	_ = x[O_100 - -100]
	_ = x[O_99 - -99]
	_ = x[O_98 - -98]
	_ = x[O_97 - -97]
	_ = x[O_96 - -96]
	_ = x[O_95 - -95]
	_ = x[O_94 - -94]
	_ = x[O_93 - -93]
	_ = x[O_92 - -92]
	_ = x[O_91 - -91]
	_ = x[O_90 - -90]
	_ = x[O_89 - -89]
	_ = x[O_88 - -88]
	_ = x[O_87 - -87]
	_ = x[O_86 - -86]
	_ = x[O_85 - -85]
	_ = x[O_84 - -84]
	_ = x[O_83 - -83]
	_ = x[O_82 - -82]
	_ = x[O_81 - -81]
	_ = x[O_80 - -80]
	_ = x[O_79 - -79]
	_ = x[O_78 - -78]
	_ = x[O_77 - -77]
	_ = x[O_76 - -76]
	_ = x[O_75 - -75]
	_ = x[O_74 - -74]
	_ = x[O_73 - -73]
	_ = x[O_72 - -72]
	_ = x[O_71 - -71]
	_ = x[O_70 - -70]
	_ = x[O_69 - -69]
	_ = x[O_68 - -68]
	_ = x[O_67 - -67]
	_ = x[O_66 - -66]
	_ = x[O_65 - -65]
	_ = x[O_64 - -64]
	_ = x[O_63 - -63]
	_ = x[O_62 - -62]
	_ = x[O_61 - -61]
	_ = x[O_60 - -60]
	_ = x[O_59 - -59]
	_ = x[O_58 - -58]
	_ = x[O_57 - -57]
	_ = x[O_56 - -56]
	_ = x[O_55 - -55]
	_ = x[O_54 - -54]
	_ = x[O_53 - -53]
	_ = x[O_52 - -52]
	_ = x[O_51 - -51]
	_ = x[O_50 - -50]
	_ = x[O_49 - -49]
	_ = x[O_48 - -48]
	_ = x[O_47 - -47]
	_ = x[O_46 - -46]
	_ = x[O_45 - -45]
	_ = x[O_44 - -44]
	_ = x[O_43 - -43]
	_ = x[O_42 - -42]
	_ = x[O_41 - -41]
	_ = x[O_40 - -40]
	_ = x[O_39 - -39]
	_ = x[O_38 - -38]
	_ = x[O_37 - -37]
	_ = x[O_36 - -36]
	_ = x[O_35 - -35]
	_ = x[O_34 - -34]
	_ = x[O_33 - -33]
	_ = x[O_32 - -32]
	_ = x[O_31 - -31]
	_ = x[O_30 - -30]
	_ = x[O_29 - -29]
	_ = x[O_28 - -28]
	_ = x[O_27 - -27]
	_ = x[O_26 - -26]
	_ = x[O_25 - -25]
	_ = x[O_24 - -24]
	_ = x[O_23 - -23]
	_ = x[O_22 - -22]
	_ = x[O_21 - -21]
	_ = x[O_20 - -20]
	_ = x[O_19 - -19]
	_ = x[O_18 - -18]
	_ = x[O_17 - -17]
	_ = x[O_16 - -16]
	_ = x[O_15 - -15]
	_ = x[O_14 - -14]
	_ = x[O_13 - -13]
	_ = x[O_12 - -12]
	_ = x[O_11 - -11]
	_ = x[O_10 - -10]
	_ = x[O_9 - -9]
	_ = x[O_8 - -8]
	_ = x[O_7 - -7]
	_ = x[O_6 - -6]
	_ = x[O_5 - -5]
	_ = x[O_4 - -4]
	_ = x[O_3 - -3]
	_ = x[O_2 - -2]
	_ = x[O_1 - -1]
	_ = x[O0-0]
	_ = x[O1-1]
	_ = x[O2-2]
	_ = x[O3-3]
	_ = x[O4-4]
	_ = x[O5-5]
	_ = x[O6-6]
	_ = x[O7-7]
	_ = x[O8-8]
	_ = x[O9-9]
	_ = x[O10-10]
	_ = x[O11-11]
	_ = x[O12-12]
	_ = x[O13-13]
	_ = x[O14-14]
	_ = x[O15-15]
	_ = x[O16-16]
	_ = x[O17-17]
	_ = x[O18-18]
	_ = x[O19-19]
	_ = x[O20-20]
	_ = x[O21-21]
	_ = x[O22-22]
	_ = x[O23-23]
	_ = x[O24-24]
	_ = x[O25-25]
	_ = x[O26-26]
	_ = x[O27-27]
	_ = x[O28-28]
	_ = x[O29-29]
	_ = x[O30-30]
	_ = x[O31-31]
	_ = x[O32-32]
	_ = x[O33-33]
	_ = x[O34-34]
	_ = x[O35-35]
	_ = x[O36-36]
	_ = x[O37-37]
	_ = x[O38-38]
	_ = x[O39-39]
	_ = x[O40-40]
	_ = x[O41-41]
	_ = x[O42-42]
	_ = x[O43-43]
	_ = x[O44-44]
	_ = x[O45-45]
	_ = x[O46-46]
	_ = x[O47-47]
	_ = x[O48-48]
	_ = x[O49-49]
	_ = x[O50-50]
	_ = x[O51-51]
	_ = x[O52-52]
	_ = x[O53-53]
	_ = x[O54-54]
	_ = x[O55-55]
	_ = x[O56-56]
	_ = x[O57-57]
	_ = x[O58-58]
	_ = x[O59-59]
	_ = x[O60-60]
	_ = x[O61-61]
	_ = x[O62-62]
	_ = x[O63-63]
	_ = x[O64-64]
	_ = x[O65-65]
	_ = x[O66-66]
	_ = x[O67-67]
	_ = x[O68-68]
	_ = x[O69-69]
	_ = x[O70-70]
	_ = x[O71-71]
	_ = x[O72-72]
	_ = x[O73-73]
	_ = x[O74-74]
	_ = x[O75-75]
	_ = x[O76-76]
	_ = x[O77-77]
	_ = x[O78-78]
	_ = x[O79-79]
	_ = x[O80-80]
	_ = x[O81-81]
	_ = x[O82-82]
	_ = x[O83-83]
	_ = x[O84-84]
	_ = x[O85-85]
	_ = x[O86-86]
	_ = x[O87-87]
	_ = x[O88-88]
	_ = x[O89-89]
	_ = x[O90-90]
	_ = x[O91-91]
	_ = x[O92-92]
	_ = x[O93-93]
	_ = x[O94-94]
	_ = x[O95-95]
	_ = x[O96-96]
	_ = x[O97-97]
	_ = x[O98-98]
	_ = x[O99-99]
	_ = x[O100-100]
	_ = x[O101-101]
	_ = x[O102-102]
	_ = x[O103-103]
	_ = x[O104-104]
	_ = x[O105-105]
	_ = x[O106-106]
	_ = x[O107-107]
	_ = x[O108-108]
	_ = x[O109-109]
	_ = x[O110-110]
	_ = x[O111-111]
	_ = x[O112-112]
	_ = x[O113-113]
	_ = x[O114-114]
	_ = x[O115-115]
	_ = x[O116-116]
	_ = x[O117-117]
	_ = x[O118-118]
	_ = x[O119-119]
	_ = x[O120-120]
	_ = x[O121-121]
	_ = x[O122-122]
	_ = x[O123-123]
	_ = x[O124-124]
	_ = x[O125-125]
	_ = x[O126-126]
	_ = x[O127-127]
}

const _Overflow8_name = "O_128O_127O_126O_125O_124O_123O_122O_121O_120O_119O_118O_117O_116O_115O_114O_113O_112O_111O_110O_109O_108O_107O_106O_105O_104O_103O_102O_101O_100O_99O_98O_97O_96O_95O_94O_93O_92O_91O_90O_89O_88O_87O_86O_85O_84O_83O_82O_81O_80O_79O_78O_77O_76O_75O_74O_73O_72O_71O_70O_69O_68O_67O_66O_65O_64O_63O_62O_61O_60O_59O_58O_57O_56O_55O_54O_53O_52O_51O_50O_49O_48O_47O_46O_45O_44O_43O_42O_41O_40O_39O_38O_37O_36O_35O_34O_33O_32O_31O_30O_29O_28O_27O_26O_25O_24O_23O_22O_21O_20O_19O_18O_17O_16O_15O_14O_13O_12O_11O_10O_9O_8O_7O_6O_5O_4O_3O_2O_1O0O1O2O3O4O5O6O7O8O9O10O11O12O13O14O15O16O17O18O19O20O21O22O23O24O25O26O27O28O29O30O31O32O33O34O35O36O37O38O39O40O41O42O43O44O45O46O47O48O49O50O51O52O53O54O55O56O57O58O59O60O61O62O63O64O65O66O67O68O69O70O71O72O73O74O75O76O77O78O79O80O81O82O83O84O85O86O87O88O89O90O91O92O93O94O95O96O97O98O99O100O101O102O103O104O105O106O107O108O109O110O111O112O113O114O115O116O117O118O119O120O121O122O123O124O125O126O127"

var _Overflow8_index = [...]uint16{0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 149, 153, 157, 161, 165, 169, 173, 177, 181, 185, 189, 193, 197, 201, 205, 209, 213, 217, 221, 225, 229, 233, 237, 241, 245, 249, 253, 257, 261, 265, 269, 273, 277, 281, 285, 289, 293, 297, 301, 305, 309, 313, 317, 321, 325, 329, 333, 337, 341, 345, 349, 353, 357, 361, 365, 369, 373, 377, 381, 385, 389, 393, 397, 401, 405, 409, 413, 417, 421, 425, 429, 433, 437, 441, 445, 449, 453, 457, 461, 465, 469, 473, 477, 481, 485, 489, 493, 497, 501, 505, 508, 511, 514, 517, 520, 523, 526, 529, 532, 534, 536, 538, 540, 542, 544, 546, 548, 550, 552, 555, 558, 561, 564, 567, 570, 573, 576, 579, 582, 585, 588, 591, 594, 597, 600, 603, 606, 609, 612, 615, 618, 621, 624, 627, 630, 633, 636, 639, 642, 645, 648, 651, 654, 657, 660, 663, 666, 669, 672, 675, 678, 681, 684, 687, 690, 693, 696, 699, 702, 705, 708, 711, 714, 717, 720, 723, 726, 729, 732, 735, 738, 741, 744, 747, 750, 753, 756, 759, 762, 765, 768, 771, 774, 777, 780, 783, 786, 789, 792, 795, 798, 801, 804, 807, 810, 813, 816, 819, 822, 826, 830, 834, 838, 842, 846, 850, 854, 858, 862, 866, 870, 874, 878, 882, 886, 890, 894, 898, 902, 906, 910, 914, 918, 922, 926, 930, 934}

func (i Overflow8) String() string {
	idx := int(i) - -128
	if i < -128 || idx >= len(_Overflow8_index)-1 {
		return "Overflow8(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Overflow8_name[_Overflow8_index[idx]:_Overflow8_index[idx+1]]
}
`

func TestGolden(t *testing.T) {
	testenv.NeedsTool(t, "go")

	dir := t.TempDir()
	for _, test := range golden {
		t.Run(test.name, func(t *testing.T) {
			input := "package test\n" + test.input
			file := test.name + ".go"
			absFile := filepath.Join(dir, file)
			err := os.WriteFile(absFile, []byte(input), 0644)
			if err != nil {
				t.Fatal(err)
			}

			pkgs := loadPackages([]string{absFile}, nil, test.trimPrefix, test.lineComment, t.Logf)
			if len(pkgs) != 1 {
				t.Fatalf("got %d parsed packages but expected 1", len(pkgs))
			}
			// Extract the name and type of the constant from the first line.
			tokens := strings.SplitN(test.input, " ", 3)
			if len(tokens) != 3 {
				t.Fatalf("%s: need type declaration on first line", test.name)
			}

			g := Generator{
				pkg:  pkgs[0],
				logf: t.Logf,
			}
			g.generate(tokens[1], findValues(tokens[1], pkgs[0]))
			got := string(g.format())
			if got != test.output {
				t.Errorf("%s: got(%d)\n====\n%q====\nexpected(%d)\n====\n%q", test.name, len(got), got, len(test.output), test.output)
			}
		})
	}
}


================================================
FILE: cmd/stringer/multifile_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go1.23 is required for os.CopyFS.
// !android is required for compatibility with endtoend_test.go.
//go:build go1.23 && !android

package main

import (
	"bytes"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/internal/diffp"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

// This file contains a test that checks the output files existence
// and content when stringer has types from multiple different input
// files to choose from.
//
// Input is specified in a txtar string.

// Several tests expect the type Foo generated in some package.
func expectFooString(pkg string) []byte {
	return fmt.Appendf(nil, `
// Header comment ignored.

package %s

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[fooX-0]
	_ = x[fooY-1]
	_ = x[fooZ-2]
}

const _Foo_name = "fooXfooYfooZ"

var _Foo_index = [...]uint8{0, 4, 8, 12}

func (i Foo) String() string {
	idx := int(i) - 0
	if i < 0 || idx >= len(_Foo_index)-1 {
		return "Foo(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Foo_name[_Foo_index[idx]:_Foo_index[idx+1]]
}`, pkg)
}

func TestMultifileStringer(t *testing.T) {
	testenv.NeedsTool(t, "go")
	stringer := stringerPath(t)

	tests := []struct {
		name        string
		args        []string
		archive     []byte
		expectFiles map[string][]byte
	}{
		{
			name: "package only",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)`),
			expectFiles: map[string][]byte{
				"foo_string.go": expectFooString("main"),
			},
		},
		{
			name: "test package only",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

func main() {}

-- main_test.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)`),
			expectFiles: map[string][]byte{
				"foo_string_test.go": expectFooString("main"),
			},
		},
		{
			name: "x_test package only",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

func main() {}

-- main_test.go --
package main_test

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)`),
			expectFiles: map[string][]byte{
				"foo_string_test.go": expectFooString("main_test"),
			},
		},
		{
			// Re-declaring the type in a less prioritized package does not change our output.
			name: "package over test package",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)

-- main_test.go --
package main

type Foo int

const (
	otherX Foo = iota
	otherY
	otherZ
)
`),
			expectFiles: map[string][]byte{
				"foo_string.go": expectFooString("main"),
			},
		},
		{
			// Re-declaring the type in a less prioritized package does not change our output.
			name: "package over x_test package",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)

-- main_test.go --
package main_test

type Foo int

const (
	otherX Foo = iota
	otherY
	otherZ
)
`),
			expectFiles: map[string][]byte{
				"foo_string.go": expectFooString("main"),
			},
		},
		{
			// Re-declaring the type in a less prioritized package does not change our output.
			name: "test package over x_test package",
			args: []string{"-type=Foo"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

-- main_test.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)

-- main_pkg_test.go --
package main_test

type Foo int

const (
	otherX Foo = iota
	otherY
	otherZ
)`),
			expectFiles: map[string][]byte{
				"foo_string_test.go": expectFooString("main"),
			},
		},
		{
			name: "unique type in each package variant",
			args: []string{"-type=Foo,Bar,Baz"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

type Foo int

const fooX Foo = 1

-- main_test.go --
package main

type Bar int

const barX Bar = 1

-- main_pkg_test.go --
package main_test

type Baz int

const bazX Baz = 1
`),
			expectFiles: map[string][]byte{
				"foo_string.go": []byte(`
// Header comment ignored.

package main

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[fooX-1]
}

const _Foo_name = "fooX"

var _Foo_index = [...]uint8{0, 4}

func (i Foo) String() string {
	idx := int(i) - 1
	if i < 1 || idx >= len(_Foo_index)-1 {
		return "Foo(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Foo_name[_Foo_index[idx]:_Foo_index[idx+1]]
}`),

				"bar_string_test.go": []byte(`
// Header comment ignored.

package main

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[barX-1]
}

const _Bar_name = "barX"

var _Bar_index = [...]uint8{0, 4}

func (i Bar) String() string {
	idx := int(i) - 1
	if i < 1 || idx >= len(_Bar_index)-1 {
		return "Bar(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Bar_name[_Bar_index[idx]:_Bar_index[idx+1]]
}`),

				"baz_string_test.go": []byte(`
// Header comment ignored.

package main_test

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[bazX-1]
}

const _Baz_name = "bazX"

var _Baz_index = [...]uint8{0, 4}

func (i Baz) String() string {
	idx := int(i) - 1
	if i < 1 || idx >= len(_Baz_index)-1 {
		return "Baz(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _Baz_name[_Baz_index[idx]:_Baz_index[idx+1]]
}`),
			},
		},

		{
			name: "package over test package with custom output",
			args: []string{"-type=Foo", "-output=custom_output.go"},
			archive: []byte(`
-- go.mod --
module foo

-- main.go --
package main

type Foo int

const (
	fooX Foo = iota
	fooY
	fooZ
)

-- main_test.go --
package main

type Foo int

const (
	otherX Foo = iota
	otherY
	otherZ
)`),
			expectFiles: map[string][]byte{
				"custom_output.go": expectFooString("main"),
			},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			tmpDir := t.TempDir()

			arFS, err := txtar.FS(txtar.Parse(tt.archive))
			if err != nil {
				t.Fatalf("txtar.FS: %s", err)
			}
			err = os.CopyFS(tmpDir, arFS)
			if err != nil {
				t.Fatalf("copy fs: %s", err)
			}
			before := dirContent(t, tmpDir)

			// Must run stringer in the temp directory, see TestTags.
			args := append(tt.args, tmpDir)
			err = runInDir(t, tmpDir, stringer, args...)
			if err != nil {
				t.Fatalf("run stringer: %s", err)
			}

			// Check that all !path files have been created with the expected content.
			for f, want := range tt.expectFiles {
				got, err := os.ReadFile(filepath.Join(tmpDir, f))
				if errors.Is(err, os.ErrNotExist) {
					t.Errorf("expected file not written during test: %s", f)
					continue
				}
				if err != nil {
					t.Fatalf("read file %q: %s", f, err)
				}
				// Trim data for more robust comparison.
				got = trimHeader(bytes.TrimSpace(got))
				want = trimHeader(bytes.TrimSpace(want))
				if !bytes.Equal(want, got) {
					t.Errorf("file %s does not have the expected content:\n%s", f, diffp.Diff("want", want, "got", got))
				}
			}

			// Check that nothing else has been created.
			after := dirContent(t, tmpDir)
			for f := range after {
				if _, expected := tt.expectFiles[f]; !expected && !before[f] {
					t.Errorf("found %q in output directory, it is neither input or expected output", f)
				}
			}

		})
	}
}

func dirContent(t *testing.T, dir string) map[string]bool {
	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatalf("read dir: %s", err)
	}

	out := map[string]bool{}
	for _, e := range entries {
		out[e.Name()] = true
	}
	return out
}

// trimHeader that stringer puts in file.
// It depends on location and interferes with comparing file content.
func trimHeader(s []byte) []byte {
	if !bytes.HasPrefix(s, []byte("//")) {
		return s
	}
	_, after, ok := bytes.Cut(s, []byte{'\n'})
	if ok {
		return after
	}
	return s
}


================================================
FILE: cmd/stringer/stringer.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Stringer is a tool to automate the creation of methods that satisfy the fmt.Stringer
// interface. Given the name of a (signed or unsigned) integer type T that has constants
// defined, stringer will create a new self-contained Go source file implementing
//
//	func (t T) String() string
//
// The file is created in the same package and directory as the package that defines T.
// It has helpful defaults designed for use with go generate.
//
// Stringer works best with constants that are consecutive values such as created using iota,
// but creates good code regardless. In the future it might also provide custom support for
// constant sets that are bit patterns.
//
// For example, given this snippet,
//
//	package painkiller
//
//	type Pill int
//
//	const (
//		Placebo Pill = iota
//		Aspirin
//		Ibuprofen
//		Paracetamol
//		Acetaminophen = Paracetamol
//	)
//
// running this command
//
//	stringer -type=Pill
//
// in the same directory will create the file pill_string.go, in package painkiller,
// containing a definition of
//
//	func (Pill) String() string
//
// That method will translate the value of a Pill constant to the string representation
// of the respective constant name, so that the call fmt.Print(painkiller.Aspirin) will
// print the string "Aspirin".
//
// Typically this process would be run using go generate, like this:
//
//	//go:generate stringer -type=Pill
//
// If multiple constants have the same value, the lexically first matching name will
// be used (in the example, Acetaminophen will print as "Paracetamol").
//
// With no arguments, it processes the package in the current directory.
// Otherwise, the arguments must name a single directory holding a Go package
// or a set of Go source files that represent a single Go package.
//
// The -type flag accepts a comma-separated list of types so a single run can
// generate methods for multiple types. The default output file is t_string.go,
// where t is the lower-cased name of the first type listed. It can be overridden
// with the -output flag.
//
// Types can also be declared in tests, in which case type declarations in the
// non-test package or its test variant are preferred over types defined in the
// package with suffix "_test".
// The default output file for type declarations in tests is t_string_test.go with t picked as above.
//
// The -linecomment flag tells stringer to generate the text of any line comment, trimmed
// of leading spaces, instead of the constant name. For instance, if the constants above had a
// Pill prefix, one could write
//
//	PillAspirin // Aspirin
//
// to suppress it in the output.
//
// The -trimprefix flag specifies a prefix to remove from the constant names
// when generating the string representations. For instance, -trimprefix=Pill
// would be an alternative way to ensure that PillAspirin.String() == "Aspirin".
package main // import "golang.org/x/tools/cmd/stringer"

import (
	"bytes"
	"flag"
	"fmt"
	"go/ast"
	"go/constant"
	"go/format"
	"go/token"
	"go/types"
	"log"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"golang.org/x/tools/go/packages"
)

var (
	typeNames   = flag.String("type", "", "comma-separated list of type names; must be set")
	output      = flag.String("output", "", "output file name; default srcdir/<type>_string.go")
	trimprefix  = flag.String("trimprefix", "", "trim the `prefix` from the generated constant names")
	linecomment = flag.Bool("linecomment", false, "use line comment text as printed text when present")
	buildTags   = flag.String("tags", "", "comma-separated list of build tags to apply")
)

// Usage is a replacement usage function for the flags package.
func Usage() {
	fmt.Fprintf(os.Stderr, "Usage of stringer:\n")
	fmt.Fprintf(os.Stderr, "\tstringer [flags] -type T [directory]\n")
	fmt.Fprintf(os.Stderr, "\tstringer [flags] -type T files... # Must be a single package\n")
	fmt.Fprintf(os.Stderr, "For more information, see:\n")
	fmt.Fprintf(os.Stderr, "\thttps://pkg.go.dev/golang.org/x/tools/cmd/stringer\n")
	fmt.Fprintf(os.Stderr, "Flags:\n")
	flag.PrintDefaults()
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("stringer: ")
	flag.Usage = Usage
	flag.Parse()
	if len(*typeNames) == 0 {
		flag.Usage()
		os.Exit(2)
	}
	types := strings.Split(*typeNames, ",")
	var tags []string
	if len(*buildTags) > 0 {
		tags = strings.Split(*buildTags, ",")
	}

	// We accept either one directory or a list of files. Which do we have?
	args := flag.Args()
	if len(args) == 0 {
		// Default: process whole package in current directory.
		args = []string{"."}
	}

	// Parse the package once.
	var dir string
	// TODO(suzmue): accept other patterns for packages (directories, list of files, import paths, etc).
	if len(args) == 1 && isDirectory(args[0]) {
		dir = args[0]
	} else {
		if len(tags) != 0 {
			log.Fatal("-tags option applies only to directories, not when files are specified")
		}
		dir = filepath.Dir(args[0])
	}

	// For each type, generate code in the first package where the type is declared.
	// The order of packages is as follows:
	// package x
	// package x compiled for tests
	// package x_test
	//
	// Each package pass could result in a separate generated file.
	// These files must have the same package and test/not-test nature as the types
	// from which they were generated.
	//
	// Types will be excluded when generated, to avoid repetitions.
	pkgs := loadPackages(args, tags, *trimprefix, *linecomment, nil /* logf */)
	sort.Slice(pkgs, func(i, j int) bool {
		// Put x_test packages last.
		iTest := strings.HasSuffix(pkgs[i].name, "_test")
		jTest := strings.HasSuffix(pkgs[j].name, "_test")
		if iTest != jTest {
			return !iTest
		}

		return len(pkgs[i].files) < len(pkgs[j].files)
	})
	for _, pkg := range pkgs {
		g := Generator{
			pkg: pkg,
		}

		// Print the header and package clause.
		g.Printf("// Code generated by \"stringer %s\"; DO NOT EDIT.\n", strings.Join(os.Args[1:], " "))
		g.Printf("\n")
		g.Printf("package %s", g.pkg.name)
		g.Printf("\n")
		g.Printf("import \"strconv\"\n") // Used by all methods.

		// Run generate for types that can be found. Keep the rest for the remainingTypes iteration.
		var foundTypes, remainingTypes []string
		for _, typeName := range types {
			values := findValues(typeName, pkg)
			if len(values) > 0 {
				g.generate(typeName, values)
				foundTypes = append(foundTypes, typeName)
			} else {
				remainingTypes = append(remainingTypes, typeName)
			}
		}
		if len(foundTypes) == 0 {
			// This package didn't have any of the relevant types, skip writing a file.
			continue
		}
		if len(remainingTypes) > 0 && output != nil && *output != "" {
			log.Fatalf("cannot write to single file (-output=%q) when matching types are found in multiple packages", *output)
		}
		types = remainingTypes

		// Format the output.
		src := g.format()

		// Write to file.
		outputName := *output
		if outputName == "" {
			// Type names will be unique across packages since only the first
			// match is picked.
			// So there won't be collisions between a package compiled for tests
			// and the separate package of tests (package foo_test).
			outputName = filepath.Join(dir, baseName(pkg, foundTypes[0]))
		}
		err := os.WriteFile(outputName, src, 0o644)
		if err != nil {
			log.Fatalf("writing output: %s", err)
		}
	}

	if len(types) > 0 {
		log.Fatalf("no values defined for types: %s", strings.Join(types, ","))
	}
}

// baseName that will put the generated code together with pkg.
func baseName(pkg *Package, typename string) string {
	suffix := "string.go"
	if pkg.hasTestFiles {
		suffix = "string_test.go"
	}
	return fmt.Sprintf("%s_%s", strings.ToLower(typename), suffix)
}

// isDirectory reports whether the named file is a directory.
func isDirectory(name string) bool {
	info, err := os.Stat(name)
	if err != nil {
		log.Fatal(err)
	}
	return info.IsDir()
}

// Generator holds the state of the analysis. Primarily used to buffer
// the output for format.Source.
type Generator struct {
	buf bytes.Buffer // Accumulated output.
	pkg *Package     // Package we are scanning.

	logf func(format string, args ...any) // test logging hook; nil when not testing
}

func (g *Generator) Printf(format string, args ...any) {
	fmt.Fprintf(&g.buf, format, args...)
}

// File holds a single parsed file and associated data.
type File struct {
	pkg  *Package  // Package to which this file belongs.
	file *ast.File // Parsed AST.
	// These fields are reset for each type being generated.
	typeName string  // Name of the constant type.
	values   []Value // Accumulator for constant values of that type.

	trimPrefix  string
	lineComment bool
}

type Package struct {
	name         string
	defs         map[*ast.Ident]types.Object
	files        []*File
	hasTestFiles bool
}

// loadPackages analyzes the single package constructed from the patterns and tags.
// loadPackages exits if there is an error.
//
// Returns all variants (such as tests) of the package.
//
// logf is a test logging hook. It can be nil when not testing.
func loadPackages(
	patterns, tags []string,
	trimPrefix string, lineComment bool,
	logf func(format string, args ...any),
) []*Package {
	cfg := &packages.Config{
		Mode: packages.NeedName | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedFiles,
		// Tests are included, let the caller decide how to fold them in.
		Tests:      true,
		BuildFlags: []string{fmt.Sprintf("-tags=%s", strings.Join(tags, " "))},
		Logf:       logf,
	}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		log.Fatal(err)
	}
	if len(pkgs) == 0 {
		log.Fatalf("error: no packages matching %v", strings.Join(patterns, " "))
	}

	out := make([]*Package, len(pkgs))
	for i, pkg := range pkgs {
		p := &Package{
			name:  pkg.Name,
			defs:  pkg.TypesInfo.Defs,
			files: make([]*File, len(pkg.Syntax)),
		}

		for j, file := range pkg.Syntax {
			p.files[j] = &File{
				file: file,
				pkg:  p,

				trimPrefix:  trimPrefix,
				lineComment: lineComment,
			}
		}

		// Keep track of test files, since we might want to generated
		// code that ends up in that kind of package.
		// Can be replaced once https://go.dev/issue/38445 lands.
		for _, f := range pkg.GoFiles {
			if strings.HasSuffix(f, "_test.go") {
				p.hasTestFiles = true
				break
			}
		}

		out[i] = p
	}
	return out
}

func findValues(typeName string, pkg *Package) []Value {
	values := make([]Value, 0, 100)
	for _, file := range pkg.files {
		// Set the state for this run of the walker.
		file.typeName = typeName
		file.values = nil
		if file.file != nil {
			ast.Inspect(file.file, file.genDecl)
			values = append(values, file.values...)
		}
	}
	return values
}

// generate produces the String method for the named type.
func (g *Generator) generate(typeName string, values []Value) {
	// Generate code that will fail if the constants change value.
	g.Printf("func _() {\n")
	g.Printf("\t// An \"invalid array index\" compiler error signifies that the constant values have changed.\n")
	g.Printf("\t// Re-run the stringer command to generate them again.\n")
	g.Printf("\tvar x [1]struct{}\n")
	for _, v := range values {
		g.Printf("\t_ = x[%s - %s]\n", v.originalName, v.str)
	}
	g.Printf("}\n")
	runs := splitIntoRuns(values)
	// The decision of which pattern to use depends on the number of
	// runs in the numbers. If there's only one, it's easy. For more than
	// one, there's a tradeoff between complexity and size of the data
	// and code vs. the simplicity of a map. A map takes more space,
	// but so does the code. The decision here (crossover at 10) is
	// arbitrary, but considers that for large numbers of runs the cost
	// of the linear scan in the switch might become important, and
	// rather than use yet another algorithm such as binary search,
	// we punt and use a map. In any case, the likelihood of a map
	// being necessary for any realistic example other than bitmasks
	// is very low. And bitmasks probably deserve their own analysis,
	// to be done some other day.
	switch {
	case len(runs) == 1:
		g.buildOneRun(runs, typeName)
	case len(runs) <= 10:
		g.buildMultipleRuns(runs, typeName)
	default:
		g.buildMap(runs, typeName)
	}
}

// splitIntoRuns breaks the values into runs of contiguous sequences.
// For example, given 1,2,3,5,6,7 it returns {1,2,3},{5,6,7}.
// The input slice is known to be non-empty.
func splitIntoRuns(values []Value) [][]Value {
	// We use stable sort so the lexically first name is chosen for equal elements.
	sort.Stable(byValue(values))
	// Remove duplicates. Stable sort has put the one we want to print first,
	// so use that one. The String method won't care about which named constant
	// was the argument, so the first name for the given value is the only one to keep.
	// We need to do this because identical values would cause the switch or map
	// to fail to compile.
	j := 1
	for i := 1; i < len(values); i++ {
		if values[i].value != values[i-1].value {
			values[j] = values[i]
			j++
		}
	}
	values = values[:j]
	runs := make([][]Value, 0, 10)
	for len(values) > 0 {
		// One contiguous sequence per outer loop.
		i := 1
		for i < len(values) && values[i].value == values[i-1].value+1 {
			i++
		}
		runs = append(runs, values[:i])
		values = values[i:]
	}
	return runs
}

// format returns the gofmt-ed contents of the Generator's buffer.
func (g *Generator) format() []byte {
	src, err := format.Source(g.buf.Bytes())
	if err != nil {
		// Should never happen, but can arise when developing this code.
		// The user can compile the output to see the error.
		log.Printf("warning: internal error: invalid Go generated: %s", err)
		log.Printf("warning: compile the package to analyze the error")
		return g.buf.Bytes()
	}
	return src
}

// Value represents a declared constant.
type Value struct {
	originalName string // The name of the constant.
	name         string // The name with trimmed prefix.
	// The value is stored as a bit pattern alone. The boolean tells us
	// whether to interpret it as an int64 or a uint64; the only place
	// this matters is when sorting.
	// Much of the time the str field is all we need; it is printed
	// by Value.String.
	value  uint64 // Will be converted to int64 when needed.
	signed bool   // Whether the constant is a signed type.
	str    string // The string representation given by the "go/constant" package.
}

func (v *Value) String() string {
	return v.str
}

// byValue lets us sort the constants into increasing order.
// We take care in the Less method to sort in signed or unsigned order,
// as appropriate.
type byValue []Value

func (b byValue) Len() int      { return len(b) }
func (b byValue) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b byValue) Less(i, j int) bool {
	if b[i].signed {
		return int64(b[i].value) < int64(b[j].value)
	}
	return b[i].value < b[j].value
}

// genDecl processes one declaration clause.
func (f *File) genDecl(node ast.Node) bool {
	decl, ok := node.(*ast.GenDecl)
	if !ok || decl.Tok != token.CONST {
		// We only care about const declarations.
		return true
	}
	// The name of the type of the constants we are declaring.
	// Can change if this is a multi-element declaration.
	typ := ""
	// Loop over the elements of the declaration. Each element is a ValueSpec:
	// a list of names possibly followed by a type, possibly followed by values.
	// If the type and value are both missing, we carry down the type (and value,
	// but the "go/types" package takes care of that).
	for _, spec := range decl.Specs {
		vspec := spec.(*ast.ValueSpec) // Guaranteed to succeed as this is CONST.
		if vspec.Type == nil && len(vspec.Values) > 0 {
			// "X = 1". With no type but a value. If the constant is untyped,
			// skip this vspec and reset the remembered type.
			typ = ""

			// If this is a simple type conversion, remember the type.
			// We don't mind if this is actually a call; a qualified call won't
			// be matched (that will be SelectorExpr, not Ident), and only unusual
			// situations will result in a function call that appears to be
			// a type conversion.
			ce, ok := vspec.Values[0].(*ast.CallExpr)
			if !ok {
				continue
			}
			id, ok := ce.Fun.(*ast.Ident)
			if !ok {
				continue
			}
			typ = id.Name
		}
		if vspec.Type != nil {
			// "X T". We have a type. Remember it.
			ident, ok := vspec.Type.(*ast.Ident)
			if !ok {
				continue
			}
			typ = ident.Name
		}
		if typ != f.typeName {
			// This is not the type we're looking for.
			continue
		}
		// We now have a list of names (from one line of source code) all being
		// declared with the desired type.
		// Grab their names and actual values and store them in f.values.
		for _, name := range vspec.Names {
			if name.Name == "_" {
				continue
			}
			// This dance lets the type checker find the values for us. It's a
			// bit tricky: look up the object declared by the name, find its
			// types.Const, and extract its value.
			obj, ok := f.pkg.defs[name]
			if !ok {
				log.Fatalf("no value for constant %s", name)
			}
			info := obj.Type().Underlying().(*types.Basic).Info()
			if info&types.IsInteger == 0 {
				log.Fatalf("can't handle non-integer constant type %s", typ)
			}
			value := obj.(*types.Const).Val() // Guaranteed to succeed as this is CONST.
			if value.Kind() != constant.Int {
				log.Fatalf("can't happen: constant is not an integer %s", name)
			}
			i64, isInt := constant.Int64Val(value)
			u64, isUint := constant.Uint64Val(value)
			if !isInt && !isUint {
				log.Fatalf("internal error: value of %s is not an integer: %s", name, value.String())
			}
			if !isInt {
				u64 = uint64(i64)
			}
			v := Value{
				originalName: name.Name,
				value:        u64,
				signed:       info&types.IsUnsigned == 0,
				str:          value.String(),
			}
			if c := vspec.Comment; f.lineComment && c != nil && len(c.List) == 1 {
				v.name = strings.TrimSpace(c.Text())
			} else {
				v.name = strings.TrimPrefix(v.originalName, f.trimPrefix)
			}
			f.values = append(f.values, v)
		}
	}
	return false
}

// Helpers

// usize returns the number of bits of the smallest unsigned integer
// type that will hold n. Used to create the smallest possible slice of
// integers to use as indexes into the concatenated strings.
func usize(n int) int {
	switch {
	case n < 1<<8:
		return 8
	case n < 1<<16:
		return 16
	default:
		// 2^32 is enough constants for anyone.
		return 32
	}
}

// declareIndexAndNameVars declares the index slices and concatenated names
// strings representing the runs of values.
func (g *Generator) declareIndexAndNameVars(runs [][]Value, typeName string) {
	var indexes, names []string
	for i, run := range runs {
		index, name := g.createIndexAndNameDecl(run, typeName, fmt.Sprintf("_%d", i))
		if len(run) != 1 {
			indexes = append(indexes, index)
		}
		names = append(names, name)
	}
	g.Printf("const (\n")
	for _, name := range names {
		g.Printf("\t%s\n", name)
	}
	g.Printf(")\n\n")

	if len(indexes) > 0 {
		g.Printf("var (")
		for _, index := range indexes {
			g.Printf("\t%s\n", index)
		}
		g.Printf(")\n\n")
	}
}

// declareIndexAndNameVar is the single-run version of declareIndexAndNameVars
func (g *Generator) declareIndexAndNameVar(run []Value, typeName string) {
	index, name := g.createIndexAndNameDecl(run, typeName, "")
	g.Printf("const %s\n", name)
	g.Printf("var %s\n", index)
}

// createIndexAndNameDecl returns the pair of declarations for the run. The caller will add "const" and "var".
func (g *Generator) createIndexAndNameDecl(run []Value, typeName string, suffix string) (string, string) {
	b := new(bytes.Buffer)
	indexes := make([]int, len(run))
	for i := range run {
		b.WriteString(run[i].name)
		indexes[i] = b.Len()
	}
	nameConst := fmt.Sprintf("_%s_name%s = %q", typeName, suffix, b.String())
	nameLen := b.Len()
	b.Reset()
	fmt.Fprintf(b, "_%s_index%s = [...]uint%d{0, ", typeName, suffix, usize(nameLen))
	for i, v := range indexes {
		if i > 0 {
			fmt.Fprintf(b, ", ")
		}
		fmt.Fprintf(b, "%d", v)
	}
	fmt.Fprintf(b, "}")
	return b.String(), nameConst
}

// declareNameVars declares the concatenated names string representing all the values in the runs.
func (g *Generator) declareNameVars(runs [][]Value, typeName string, suffix string) {
	g.Printf("const _%s_name%s = \"", typeName, suffix)
	for _, run := range runs {
		for i := range run {
			g.Printf("%s", run[i].name)
		}
	}
	g.Printf("\"\n")
}

// buildOneRun generates the variables and String method for a single run of contiguous values.
func (g *Generator) buildOneRun(runs [][]Value, typeName string) {
	values := runs[0]
	g.Printf("\n")
	g.declareIndexAndNameVar(values, typeName)
	g.Printf(stringOneRun, typeName, values[0].String())
}

// Arguments to format are:
//
//	[1]: type name
//	[2]: lowest defined value for type, as a string
const stringOneRun = `func (i %[1]s) String() string {
	idx := int(i) - %[2]s
	if i < %[2]s || idx >= len(_%[1]s_index)-1 {
		return "%[1]s(" + strconv.FormatInt(int64(i), 10) + ")"
	}
	return _%[1]s_name[_%[1]s_index[idx] : _%[1]s_index[idx+1]]
}
`

// buildMultipleRuns generates the variables and String method for multiple runs of contiguous values.
// For this pattern, a single Printf format won't do.
func (g *Generator) buildMultipleRuns(runs [][]Value, typeName string) {
	g.Printf("\n")
	g.declareIndexAndNameVars(runs, typeName)
	g.Printf("func (i %s) String() string {\n", typeName)
	g.Printf("\tswitch {\n")
	for i, values := range runs {
		if len(values) == 1 {
			g.Printf("\tcase i == %s:\n", &values[0])
			g.Printf("\t\treturn _%s_name_%d\n", typeName, i)
			continue
		}
		if values[0].value == 0 && !values[0].signed {
			// For an unsigned lower bound of 0, "0 <= i" would be redundant.
			g.Printf("\tcase i <= %s:\n", &values[len(values)-1])
		} else {
			g.Printf("\tcase %s <= i && i <= %s:\n", &values[0], &values[len(values)-1])
		}
		if values[0].value != 0 {
			g.Printf("\t\ti -= %s\n", &values[0])
		}
		g.Printf("\t\treturn _%s_name_%d[_%s_index_%d[i]:_%s_index_%d[i+1]]\n",
			typeName, i, typeName, i, typeName, i)
	}
	g.Printf("\tdefault:\n")
	g.Printf("\t\treturn \"%s(\" + strconv.FormatInt(int64(i), 10) + \")\"\n", typeName)
	g.Printf("\t}\n")
	g.Printf("}\n")
}

// buildMap handles the case where the space is so sparse a map is a reasonable fallback.
// It's a rare situation but has simple code.
func (g *Generator) buildMap(runs [][]Value, typeName string) {
	g.Printf("\n")
	g.declareNameVars(runs, typeName, "")
	g.Printf("\nvar _%s_map = map[%s]string{\n", typeName, typeName)
	n := 0
	for _, values := range runs {
		for _, value := range values {
			g.Printf("\t%s: _%s_name[%d:%d],\n", &value, typeName, n, n+len(value.name))
			n += len(value.name)
		}
	}
	g.Printf("}\n\n")
	g.Printf(stringMap, typeName)
}

// Argument to format is the type name.
const stringMap = `func (i %[1]s) String() string {
	if str, ok := _%[1]s_map[i]; ok {
		return str
	}
	return "%[1]s(" + strconv.FormatInt(int64(i), 10) + ")"
}
`


================================================
FILE: cmd/stringer/testdata/cgo.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Import "C" shouldn't be imported.

package main

/*
#define HELLO 1
*/
import "C"

import "fmt"

type Cgo uint32

const (
	// MustScanSubDirs indicates that events were coalesced hierarchically.
	MustScanSubDirs Cgo = 1 << iota
)

func main() {
	_ = C.HELLO
	ck(MustScanSubDirs, "MustScanSubDirs")
}

func ck(day Cgo, str string) {
	if fmt.Sprint(day) != str {
		panic("cgo.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/conv.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Check that constants defined as a conversion are accepted.

package main

import "fmt"

type Other int // Imagine this is in another package.

const (
	alpha Other = iota
	beta
	gamma
	delta
)

type Conv int

const (
	Alpha = Conv(alpha)
	Beta  = Conv(beta)
	Gamma = Conv(gamma)
	Delta = Conv(delta)
)

func main() {
	ck(Alpha, "Alpha")
	ck(Beta, "Beta")
	ck(Gamma, "Gamma")
	ck(Delta, "Delta")
	ck(42, "Conv(42)")
}

func ck(c Conv, str string) {
	if fmt.Sprint(c) != str {
		panic("conv.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/conv2.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is a version of ../conv.go with type params

// Check that constants defined as a conversion are accepted.

package main

import "fmt"

// For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
// type Other[T interface{ ~int | ~uint }] T // Imagine this is in another package.
type Other int

const (
	// alpha Other[int] = iota
	alpha Other = iota
	beta
	gamma
	delta
)

// type Conv2 Other[int]
type Conv2 Other

const (
	Alpha = Conv2(alpha)
	Beta  = Conv2(beta)
	Gamma = Conv2(gamma)
	Delta = Conv2(delta)
)

func main() {
	ck(Alpha, "Alpha")
	ck(Beta, "Beta")
	ck(Gamma, "Gamma")
	ck(Delta, "Delta")
	ck(42, "Conv2(42)")
}

func ck(c Conv2, str string) {
	if fmt.Sprint(c) != str {
		panic("conv2.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/day.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Simple test: enumeration of type int starting at 0.

package main

import "fmt"

type Day int

const (
	Monday Day = iota
	Tuesday
	Wednesday
	Thursday
	Friday
	Saturday
	Sunday
)

func main() {
	ck(Monday, "Monday")
	ck(Tuesday, "Tuesday")
	ck(Wednesday, "Wednesday")
	ck(Thursday, "Thursday")
	ck(Friday, "Friday")
	ck(Saturday, "Saturday")
	ck(Sunday, "Sunday")
	ck(-127, "Day(-127)")
	ck(127, "Day(127)")
}

func ck(day Day, str string) {
	if fmt.Sprint(day) != str {
		panic("day.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/gap.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Gaps and an offset.

package main

import "fmt"

type Gap int

const (
	Two    Gap = 2
	Three  Gap = 3
	Five   Gap = 5
	Six    Gap = 6
	Seven  Gap = 7
	Eight  Gap = 8
	Nine   Gap = 9
	Eleven Gap = 11
)

func main() {
	ck(0, "Gap(0)")
	ck(1, "Gap(1)")
	ck(Two, "Two")
	ck(Three, "Three")
	ck(4, "Gap(4)")
	ck(Five, "Five")
	ck(Six, "Six")
	ck(Seven, "Seven")
	ck(Eight, "Eight")
	ck(Nine, "Nine")
	ck(10, "Gap(10)")
	ck(Eleven, "Eleven")
	ck(12, "Gap(12)")
}

func ck(gap Gap, str string) {
	if fmt.Sprint(gap) != str {
		panic("gap.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/int8overflow.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Check that int8 bounds checking doesn't cause panics or compilation errors.

package main

import (
	"fmt"
	"strings"
)

type Int8overflow int8

const (
	I_128 Int8overflow = -128
	I_127 Int8overflow = -127
	I_126 Int8overflow = -126
	I_125 Int8overflow = -125
	I_124 Int8overflow = -124
	I_123 Int8overflow = -123
	I_122 Int8overflow = -122
	I_121 Int8overflow = -121
	I_120 Int8overflow = -120
	I_119 Int8overflow = -119
	I_118 Int8overflow = -118
	I_117 Int8overflow = -117
	I_116 Int8overflow = -116
	I_115 Int8overflow = -115
	I_114 Int8overflow = -114
	I_113 Int8overflow = -113
	I_112 Int8overflow = -112
	I_111 Int8overflow = -111
	I_110 Int8overflow = -110
	I_109 Int8overflow = -109
	I_108 Int8overflow = -108
	I_107 Int8overflow = -107
	I_106 Int8overflow = -106
	I_105 Int8overflow = -105
	I_104 Int8overflow = -104
	I_103 Int8overflow = -103
	I_102 Int8overflow = -102
	I_101 Int8overflow = -101
	I_100 Int8overflow = -100
	I_99  Int8overflow = -99
	I_98  Int8overflow = -98
	I_97  Int8overflow = -97
	I_96  Int8overflow = -96
	I_95  Int8overflow = -95
	I_94  Int8overflow = -94
	I_93  Int8overflow = -93
	I_92  Int8overflow = -92
	I_91  Int8overflow = -91
	I_90  Int8overflow = -90
	I_89  Int8overflow = -89
	I_88  Int8overflow = -88
	I_87  Int8overflow = -87
	I_86  Int8overflow = -86
	I_85  Int8overflow = -85
	I_84  Int8overflow = -84
	I_83  Int8overflow = -83
	I_82  Int8overflow = -82
	I_81  Int8overflow = -81
	I_80  Int8overflow = -80
	I_79  Int8overflow = -79
	I_78  Int8overflow = -78
	I_77  Int8overflow = -77
	I_76  Int8overflow = -76
	I_75  Int8overflow = -75
	I_74  Int8overflow = -74
	I_73  Int8overflow = -73
	I_72  Int8overflow = -72
	I_71  Int8overflow = -71
	I_70  Int8overflow = -70
	I_69  Int8overflow = -69
	I_68  Int8overflow = -68
	I_67  Int8overflow = -67
	I_66  Int8overflow = -66
	I_65  Int8overflow = -65
	I_64  Int8overflow = -64
	I_63  Int8overflow = -63
	I_62  Int8overflow = -62
	I_61  Int8overflow = -61
	I_60  Int8overflow = -60
	I_59  Int8overflow = -59
	I_58  Int8overflow = -58
	I_57  Int8overflow = -57
	I_56  Int8overflow = -56
	I_55  Int8overflow = -55
	I_54  Int8overflow = -54
	I_53  Int8overflow = -53
	I_52  Int8overflow = -52
	I_51  Int8overflow = -51
	I_50  Int8overflow = -50
	I_49  Int8overflow = -49
	I_48  Int8overflow = -48
	I_47  Int8overflow = -47
	I_46  Int8overflow = -46
	I_45  Int8overflow = -45
	I_44  Int8overflow = -44
	I_43  Int8overflow = -43
	I_42  Int8overflow = -42
	I_41  Int8overflow = -41
	I_40  Int8overflow = -40
	I_39  Int8overflow = -39
	I_38  Int8overflow = -38
	I_37  Int8overflow = -37
	I_36  Int8overflow = -36
	I_35  Int8overflow = -35
	I_34  Int8overflow = -34
	I_33  Int8overflow = -33
	I_32  Int8overflow = -32
	I_31  Int8overflow = -31
	I_30  Int8overflow = -30
	I_29  Int8overflow = -29
	I_28  Int8overflow = -28
	I_27  Int8overflow = -27
	I_26  Int8overflow = -26
	I_25  Int8overflow = -25
	I_24  Int8overflow = -24
	I_23  Int8overflow = -23
	I_22  Int8overflow = -22
	I_21  Int8overflow = -21
	I_20  Int8overflow = -20
	I_19  Int8overflow = -19
	I_18  Int8overflow = -18
	I_17  Int8overflow = -17
	I_16  Int8overflow = -16
	I_15  Int8overflow = -15
	I_14  Int8overflow = -14
	I_13  Int8overflow = -13
	I_12  Int8overflow = -12
	I_11  Int8overflow = -11
	I_10  Int8overflow = -10
	I_9   Int8overflow = -9
	I_8   Int8overflow = -8
	I_7   Int8overflow = -7
	I_6   Int8overflow = -6
	I_5   Int8overflow = -5
	I_4   Int8overflow = -4
	I_3   Int8overflow = -3
	I_2   Int8overflow = -2
	I_1   Int8overflow = -1
	I0    Int8overflow = 0
	I1    Int8overflow = 1
	I2    Int8overflow = 2
	I3    Int8overflow = 3
	I4    Int8overflow = 4
	I5    Int8overflow = 5
	I6    Int8overflow = 6
	I7    Int8overflow = 7
	I8    Int8overflow = 8
	I9    Int8overflow = 9
	I10   Int8overflow = 10
	I11   Int8overflow = 11
	I12   Int8overflow = 12
	I13   Int8overflow = 13
	I14   Int8overflow = 14
	I15   Int8overflow = 15
	I16   Int8overflow = 16
	I17   Int8overflow = 17
	I18   Int8overflow = 18
	I19   Int8overflow = 19
	I20   Int8overflow = 20
	I21   Int8overflow = 21
	I22   Int8overflow = 22
	I23   Int8overflow = 23
	I24   Int8overflow = 24
	I25   Int8overflow = 25
	I26   Int8overflow = 26
	I27   Int8overflow = 27
	I28   Int8overflow = 28
	I29   Int8overflow = 29
	I30   Int8overflow = 30
	I31   Int8overflow = 31
	I32   Int8overflow = 32
	I33   Int8overflow = 33
	I34   Int8overflow = 34
	I35   Int8overflow = 35
	I36   Int8overflow = 36
	I37   Int8overflow = 37
	I38   Int8overflow = 38
	I39   Int8overflow = 39
	I40   Int8overflow = 40
	I41   Int8overflow = 41
	I42   Int8overflow = 42
	I43   Int8overflow = 43
	I44   Int8overflow = 44
	I45   Int8overflow = 45
	I46   Int8overflow = 46
	I47   Int8overflow = 47
	I48   Int8overflow = 48
	I49   Int8overflow = 49
	I50   Int8overflow = 50
	I51   Int8overflow = 51
	I52   Int8overflow = 52
	I53   Int8overflow = 53
	I54   Int8overflow = 54
	I55   Int8overflow = 55
	I56   Int8overflow = 56
	I57   Int8overflow = 57
	I58   Int8overflow = 58
	I59   Int8overflow = 59
	I60   Int8overflow = 60
	I61   Int8overflow = 61
	I62   Int8overflow = 62
	I63   Int8overflow = 63
	I64   Int8overflow = 64
	I65   Int8overflow = 65
	I66   Int8overflow = 66
	I67   Int8overflow = 67
	I68   Int8overflow = 68
	I69   Int8overflow = 69
	I70   Int8overflow = 70
	I71   Int8overflow = 71
	I72   Int8overflow = 72
	I73   Int8overflow = 73
	I74   Int8overflow = 74
	I75   Int8overflow = 75
	I76   Int8overflow = 76
	I77   Int8overflow = 77
	I78   Int8overflow = 78
	I79   Int8overflow = 79
	I80   Int8overflow = 80
	I81   Int8overflow = 81
	I82   Int8overflow = 82
	I83   Int8overflow = 83
	I84   Int8overflow = 84
	I85   Int8overflow = 85
	I86   Int8overflow = 86
	I87   Int8overflow = 87
	I88   Int8overflow = 88
	I89   Int8overflow = 89
	I90   Int8overflow = 90
	I91   Int8overflow = 91
	I92   Int8overflow = 92
	I93   Int8overflow = 93
	I94   Int8overflow = 94
	I95   Int8overflow = 95
	I96   Int8overflow = 96
	I97   Int8overflow = 97
	I98   Int8overflow = 98
	I99   Int8overflow = 99
	I100  Int8overflow = 100
	I101  Int8overflow = 101
	I102  Int8overflow = 102
	I103  Int8overflow = 103
	I104  Int8overflow = 104
	I105  Int8overflow = 105
	I106  Int8overflow = 106
	I107  Int8overflow = 107
	I108  Int8overflow = 108
	I109  Int8overflow = 109
	I110  Int8overflow = 110
	I111  Int8overflow = 111
	I112  Int8overflow = 112
	I113  Int8overflow = 113
	I114  Int8overflow = 114
	I115  Int8overflow = 115
	I116  Int8overflow = 116
	I117  Int8overflow = 117
	I118  Int8overflow = 118
	I119  Int8overflow = 119
	I120  Int8overflow = 120
	I121  Int8overflow = 121
	I122  Int8overflow = 122
	I123  Int8overflow = 123
	I124  Int8overflow = 124
	I125  Int8overflow = 125
	I126  Int8overflow = 126
	I127  Int8overflow = 127
)

func main() {
	testValues := []Int8overflow{
		I_128,
		I_127,
		I_1,
		I0,
		I1,
		I126,
		I127,
	}

	for _, val := range testValues {
		want := strings.ReplaceAll(fmt.Sprintf("I%d", int(val)), "-", "_")
		result := fmt.Sprint(val)
		if result != want {
			panic(fmt.Sprintf("int8overflow.go: got %s, want %s for value %d", result, want, int8(val)))
		}
	}
}


================================================
FILE: cmd/stringer/testdata/num.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Signed integers spanning zero.

package main

import "fmt"

type Num int

const (
	m_2 Num = -2 + iota
	m_1
	m0
	m1
	m2
)

func main() {
	ck(-3, "Num(-3)")
	ck(m_2, "m_2")
	ck(m_1, "m_1")
	ck(m0, "m0")
	ck(m1, "m1")
	ck(m2, "m2")
	ck(3, "Num(3)")
}

func ck(num Num, str string) {
	if fmt.Sprint(num) != str {
		panic("num.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/number.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Enumeration with an offset.
// Also includes a duplicate.

package main

import "fmt"

type Number int

const (
	_ Number = iota
	One
	Two
	Three
	AnotherOne = One // Duplicate; note that AnotherOne doesn't appear below.
)

func main() {
	ck(One, "One")
	ck(Two, "Two")
	ck(Three, "Three")
	ck(AnotherOne, "One")
	ck(127, "Number(127)")
}

func ck(num Number, str string) {
	if fmt.Sprint(num) != str {
		panic("number.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/prime.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Enough gaps to trigger a map implementation of the method.
// Also includes a duplicate to test that it doesn't cause problems

package main

import "fmt"

type Prime int

const (
	p2  Prime = 2
	p3  Prime = 3
	p5  Prime = 5
	p7  Prime = 7
	p77 Prime = 7 // Duplicate; note that p77 doesn't appear below.
	p11 Prime = 11
	p13 Prime = 13
	p17 Prime = 17
	p19 Prime = 19
	p23 Prime = 23
	p29 Prime = 29
	p37 Prime = 31
	p41 Prime = 41
	p43 Prime = 43
)

func main() {
	ck(0, "Prime(0)")
	ck(1, "Prime(1)")
	ck(p2, "p2")
	ck(p3, "p3")
	ck(4, "Prime(4)")
	ck(p5, "p5")
	ck(p7, "p7")
	ck(p77, "p7")
	ck(p11, "p11")
	ck(p13, "p13")
	ck(p17, "p17")
	ck(p19, "p19")
	ck(p23, "p23")
	ck(p29, "p29")
	ck(p37, "p37")
	ck(p41, "p41")
	ck(p43, "p43")
	ck(44, "Prime(44)")
}

func ck(prime Prime, str string) {
	if fmt.Sprint(prime) != str {
		panic("prime.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/prime2.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is a version of ../prime.go with type params

// Enough gaps to trigger a map implementation of the method.
// Also includes a duplicate to test that it doesn't cause problems

package main

import "fmt"

// For now, a lone type parameter is not permitted as RHS in a type declaration (issue #45639).
// type Likeint[T interface{ ~int | ~uint8 }] T
type Likeint int

// type Prime2 Likeint[int]
type Prime2 Likeint

const (
	p2  Prime2 = 2
	p3  Prime2 = 3
	p5  Prime2 = 5
	p7  Prime2 = 7
	p77 Prime2 = 7 // Duplicate; note that p77 doesn't appear below.
	p11 Prime2 = 11
	p13 Prime2 = 13
	p17 Prime2 = 17
	p19 Prime2 = 19
	p23 Prime2 = 23
	p29 Prime2 = 29
	p37 Prime2 = 31
	p41 Prime2 = 41
	p43 Prime2 = 43
)

func main() {
	ck(0, "Prime2(0)")
	ck(1, "Prime2(1)")
	ck(p2, "p2")
	ck(p3, "p3")
	ck(4, "Prime2(4)")
	ck(p5, "p5")
	ck(p7, "p7")
	ck(p77, "p7")
	ck(p11, "p11")
	ck(p13, "p13")
	ck(p17, "p17")
	ck(p19, "p19")
	ck(p23, "p23")
	ck(p29, "p29")
	ck(p37, "p37")
	ck(p41, "p41")
	ck(p43, "p43")
	ck(44, "Prime2(44)")
}

func ck(prime Prime2, str string) {
	if fmt.Sprint(prime) != str {
		panic("prime2.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/tag_main.go
================================================
// No build tag in this file.

package main

type Const int

const (
	A Const = iota
	B
	C
)


================================================
FILE: cmd/stringer/testdata/tag_tag.go
================================================
// This file has a build tag "tag"

// +build tag

package main

const TagProtected Const = C + 1


================================================
FILE: cmd/stringer/testdata/unum.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Unsigned integers spanning zero.

package main

import "fmt"

type Unum uint8

const (
	m_2 Unum = iota + 253
	m_1
)

const (
	m0 Unum = iota
	m1
	m2
)

func main() {
	ck(^Unum(0)-3, "Unum(252)")
	ck(m_2, "m_2")
	ck(m_1, "m_1")
	ck(m0, "m0")
	ck(m1, "m1")
	ck(m2, "m2")
	ck(3, "Unum(3)")
}

func ck(unum Unum, str string) {
	if fmt.Sprint(unum) != str {
		panic("unum.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/unum2.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Unsigned integers - check maximum size

package main

import "fmt"

type Unum2 uint8

const (
	Zero Unum2 = iota
	One
	Two
)

func main() {
	ck(Zero, "Zero")
	ck(One, "One")
	ck(Two, "Two")
	ck(3, "Unum2(3)")
	ck(255, "Unum2(255)")
}

func ck(unum Unum2, str string) {
	if fmt.Sprint(unum) != str {
		panic("unum.go: " + str)
	}
}


================================================
FILE: cmd/stringer/testdata/vary_day.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is the same as day.go except the constants have different values.

package main

import "fmt"

type Day int

const (
	Sunday Day = iota
	Monday
	Tuesday
	Wednesday
	Thursday
	Friday
	Saturday
)

func main() {
	ck(Monday, "Monday")
	ck(Tuesday, "Tuesday")
	ck(Wednesday, "Wednesday")
	ck(Thursday, "Thursday")
	ck(Friday, "Friday")
	ck(Saturday, "Saturday")
	ck(Sunday, "Sunday")
	ck(-127, "Day(-127)")
	ck(127, "Day(127)")
}

func ck(day Day, str string) {
	if fmt.Sprint(day) != str {
		panic("day.go: " + str)
	}
}


================================================
FILE: cmd/stringer/util_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for some of the internal functions.

package main

import (
	"fmt"
	"testing"
)

// Helpers to save typing in the test cases.
type u []uint64
type uu [][]uint64

type SplitTest struct {
	input  u
	output uu
	signed bool
}

var (
	m2  = uint64(2)
	m1  = uint64(1)
	m0  = uint64(0)
	m_1 = ^uint64(0)     // -1 when signed.
	m_2 = ^uint64(0) - 1 // -2 when signed.
)

var splitTests = []SplitTest{
	// No need for a test for the empty case; that's picked off before splitIntoRuns.
	// Single value.
	{u{1}, uu{u{1}}, false},
	// Out of order.
	{u{3, 2, 1}, uu{u{1, 2, 3}}, true},
	// Out of order.
	{u{3, 2, 1}, uu{u{1, 2, 3}}, false},
	// A gap at the beginning.
	{u{1, 33, 32, 31}, uu{u{1}, u{31, 32, 33}}, true},
	// A gap in the middle, in mixed order.
	{u{33, 7, 32, 31, 9, 8}, uu{u{7, 8, 9}, u{31, 32, 33}}, true},
	// Gaps throughout
	{u{33, 44, 1, 32, 45, 31}, uu{u{1}, u{31, 32, 33}, u{44, 45}}, true},
	// Unsigned values spanning 0.
	{u{m1, m0, m_1, m2, m_2}, uu{u{m0, m1, m2}, u{m_2, m_1}}, false},
	// Signed values spanning 0
	{u{m1, m0, m_1, m2, m_2}, uu{u{m_2, m_1, m0, m1, m2}}, true},
}

func TestSplitIntoRuns(t *testing.T) {
Outer:
	for n, test := range splitTests {
		values := make([]Value, len(test.input))
		for i, v := range test.input {
			values[i] = Value{"", "", v, test.signed, fmt.Sprint(v)}
		}
		runs := splitIntoRuns(values)
		if len(runs) != len(test.output) {
			t.Errorf("#%d: %v: got %d runs; expected %d", n, test.input, len(runs), len(test.output))
			continue
		}
		for i, run := range runs {
			if len(run) != len(test.output[i]) {
				t.Errorf("#%d: got %v; expected %v", n, runs, test.output)
				continue Outer
			}
			for j, v := range run {
				if v.value != test.output[i][j] {
					t.Errorf("#%d: got %v; expected %v", n, runs, test.output)
					continue Outer
				}
			}
		}
	}
}


================================================
FILE: cmd/toolstash/buildall
================================================
#!/bin/bash

# Usage: buildall [-e] [-nocmp] [-work]
#
# Builds everything (std) for every GOOS/GOARCH combination but installs nothing.
#
# By default, runs the builds with -toolexec 'toolstash -cmp', to test that the
# toolchain is producing bit identical output to a previous known good toolchain.
#
# Options:
#	-e: stop at first failure
#	-nocmp: turn off toolstash -cmp; just check that ordinary builds succeed
#	-work: pass -work to go command

sete=false
if [ "$1" = "-e" ]; then
	sete=true
	shift
fi

cmp=true
if [ "$1" = "-nocmp" ]; then
	cmp=false
	shift
fi

work=""
if [ "$1" = "-work" ]; then
	work="-work"
	shift
fi

cd $(go env GOROOT)/src
go install cmd/compile cmd/link cmd/asm || exit 1
pattern="$1"
if [ "$pattern" = "" ]; then
	pattern=.
fi

targets="$(go tool dist list; echo linux/386/softfloat)"
targets="$(echo "$targets" | tr '/' '-' | sort | grep -E "$pattern" | grep -E -v 'android-arm|darwin-arm')"

# put linux first in the target list to get all the architectures up front.
targets="$(echo "$targets" | grep -E 'linux') $(echo "$targets" | grep -E -v 'linux')"

if [ "$sete" = true ]; then
	set -e
fi
for target in $targets
do
	echo $target
	export GOOS=$(echo $target | sed 's/-.*//')
	export GOARCH=$(echo $target | sed 's/.*-//')
	unset GO386
	if [ "$GOARCH" = "softfloat" ]; then
		export GOARCH=386
		export GO386=softfloat
	fi
	if $cmp; then
		if [ "$GOOS" = "android" ]; then
			go build $work -a -toolexec 'toolstash -cmp' std
		else
			go build $work -a -toolexec 'toolstash -cmp' std cmd
		fi
	else
		go build $work -a std
	fi
done


================================================
FILE: cmd/toolstash/cmp.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"io"
	"log"
	"os"
	"regexp"
	"strconv"
	"strings"
)

var (
	hexDumpRE = regexp.MustCompile(`^\t(0x[0-9a-f]{4,})(( ([0-9a-f]{2}|  )){16})  [ -\x7F]{1,16}\n`)
	listingRE = regexp.MustCompile(`^\t(0x[0-9a-f]{4,}) ([0-9]{4,}) \(.*:[0-9]+\)\t`)
)

// okdiffs lists regular expressions for lines to consider minor mismatches.
// If one of these regexps matches both of a pair of unequal lines, the mismatch
// is reported but not treated as the one worth looking for.
// For example, differences in the TEXT line are typically frame size
// changes due to optimization decisions made in the body of the function.
// Better to keep looking for the actual difference.
// Similarly, forward jumps might have different offsets due to a
// change in instruction encoding later on.
// Better to find that change.
var okdiffs = []*regexp.Regexp{
	regexp.MustCompile(`\)	TEXT[ 	].*,\$`),
	regexp.MustCompile(`\)	WORD[ 	].*,\$`),
	regexp.MustCompile(`\)	(B|BR|JMP)	`),
	regexp.MustCompile(`\)	FUNCDATA	`),
	regexp.MustCompile(`\\(z|x00)`),
	regexp.MustCompile(`\$\([0-9]\.[0-9]+e[+\-][0-9]+\)`),
	regexp.MustCompile(`size=.*value=.*args=.*locals=`),
}

func compareLogs(outfile string) string {
	f1, err := os.Open(outfile + ".log")
	if err != nil {
		log.Fatal(err)
	}
	defer f1.Close()

	f2, err := os.Open(outfile + ".stash.log")
	if err != nil {
		log.Fatal(err)
	}
	defer f2.Close()

	b1 := bufio.NewReader(f1)
	b2 := bufio.NewReader(f2)

	offset := int64(0)
	textOffset := offset
	textLineno := 0
	lineno := 0
	var line1, line2 string
	var prefix bytes.Buffer
Reading:
	for {
		var err1, err2 error
		line1, err1 = b1.ReadString('\n')
		line2, err2 = b2.ReadString('\n')
		if strings.Contains(line1, ")\tTEXT\t") {
			textOffset = offset
			textLineno = lineno
		}
		offset += int64(len(line1))
		lineno++
		if err1 == io.EOF && err2 == io.EOF {
			return "no differences in debugging output"
		}

		if lineno == 1 || line1 == line2 && err1 == nil && err2 == nil {
			continue
		}
		// Lines are inconsistent. Worth stopping?
		for _, re := range okdiffs {
			if re.MatchString(line1) && re.MatchString(line2) {
				fmt.Fprintf(&prefix, "inconsistent log line:\n%s:%d:\n\t%s\n%s:%d:\n\t%s\n\n",
					f1.Name(), lineno, strings.TrimSuffix(line1, "\n"),
					f2.Name(), lineno, strings.TrimSuffix(line2, "\n"))
				continue Reading
			}
		}

		if err1 != nil {
			line1 = err1.Error()
		}
		if err2 != nil {
			line2 = err2.Error()
		}
		break
	}

	msg := fmt.Sprintf("inconsistent log line:\n%s:%d:\n\t%s\n%s:%d:\n\t%s",
		f1.Name(), lineno, strings.TrimSuffix(line1, "\n"),
		f2.Name(), lineno, strings.TrimSuffix(line2, "\n"))

	if m := hexDumpRE.FindStringSubmatch(line1); m != nil {
		target, err := strconv.ParseUint(m[1], 0, 64)
		if err != nil {
			goto Skip
		}

		m2 := hexDumpRE.FindStringSubmatch(line2)
		if m2 == nil {
			goto Skip
		}

		fields1 := strings.Fields(m[2])
		fields2 := strings.Fields(m2[2])
		i := 0
		for i < len(fields1) && i < len(fields2) && fields1[i] == fields2[i] {
			i++
		}
		target += uint64(i)

		f1.Seek(textOffset, 0)
		b1 = bufio.NewReader(f1)
		last := ""
		lineno := textLineno
		limitAddr := uint64(0)
		lastAddr := uint64(0)
		for {
			line1, err1 := b1.ReadString('\n')
			if err1 != nil {
				break
			}
			lineno++
			if m := listingRE.FindStringSubmatch(line1); m != nil {
				addr, _ := strconv.ParseUint(m[1], 0, 64)
				if addr > target {
					limitAddr = addr
					break
				}
				last = line1
				lastAddr = addr
			} else if hexDumpRE.FindStringSubmatch(line1) != nil {
				break
			}
		}
		if last != "" {
			msg = fmt.Sprintf("assembly instruction at %#04x-%#04x:\n%s:%d\n\t%s\n\n%s",
				lastAddr, limitAddr, f1.Name(), lineno-1, strings.TrimSuffix(last, "\n"), msg)
		}
	}
Skip:

	return prefix.String() + msg
}


================================================
FILE: cmd/toolstash/main.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Toolstash provides a way to save, run, and restore a known good copy of the Go toolchain
// and to compare the object files generated by two toolchains.
//
// Usage:
//
//	toolstash [-n] [-v] save [tool...]
//	toolstash [-n] [-v] restore [tool...]
//	toolstash [-n] [-v] [-t] go run x.go
//	toolstash [-n] [-v] [-t] [-cmp] compile x.go
//
// The toolstash command manages a “stashed” copy of the Go toolchain
// kept in $GOROOT/pkg/toolstash. In this case, the toolchain means the
// tools available with the 'go tool' command as well as the go, godoc, and gofmt
// binaries.
//
// The command “toolstash save”, typically run when the toolchain is known to be working,
// copies the toolchain from its installed location to the toolstash directory.
// Its inverse, “toolchain restore”, typically run when the toolchain is known to be broken,
// copies the toolchain from the toolstash directory back to the installed locations.
// If additional arguments are given, the save or restore applies only to the named tools.
// Otherwise, it applies to all tools.
//
// Otherwise, toolstash's arguments should be a command line beginning with the
// name of a toolchain binary, which may be a short name like compile or a complete path
// to an installed binary. Toolstash runs the command line using the stashed
// copy of the binary instead of the installed one.
//
// The -n flag causes toolstash to print the commands that would be executed
// but not execute them. The combination -n -cmp shows the two commands
// that would be compared and then exits successfully. A real -cmp run might
// run additional commands for diagnosis of an output mismatch.
//
// The -v flag causes toolstash to print the commands being executed.
//
// The -t flag causes toolstash to print the time elapsed during while the
// command ran.
//
// # Comparing
//
// The -cmp flag causes toolstash to run both the installed and the stashed
// copy of an assembler or compiler and check that they produce identical
// object files. If not, toolstash reports the mismatch and exits with a failure status.
// As part of reporting the mismatch, toolstash reinvokes the command with
// the -S=2 flag and identifies the first divergence in the assembly output.
// If the command is a Go compiler, toolstash also determines whether the
// difference is triggered by optimization passes.
// On failure, toolstash leaves additional information in files named
// similarly to the default output file. If the compilation would normally
// produce a file x.6, the output from the stashed tool is left in x.6.stash
// and the debugging traces are left in x.6.log and x.6.stash.log.
//
// The -cmp flag is a no-op when the command line is not invoking an
// assembler or compiler.
//
// For example, when working on code cleanup that should not affect
// compiler output, toolstash can be used to compare the old and new
// compiler output:
//
//	toolstash save
//	<edit compiler sources>
//	go tool dist install cmd/compile # install compiler only
//	toolstash -cmp compile x.go
//
// # Go Command Integration
//
// The go command accepts a -toolexec flag that specifies a program
// to use to run the build tools.
//
// To build with the stashed tools:
//
//	go build -toolexec toolstash x.go
//
// To build with the stashed go command and the stashed tools:
//
//	toolstash go build -toolexec toolstash x.go
//
// To verify that code cleanup in the compilers does not make any
// changes to the objects being generated for the entire tree:
//
//	# Build working tree and save tools.
//	./make.bash
//	toolstash save
//
//	<edit compiler sources>
//
//	# Install new tools, but do not rebuild the rest of tree,
//	# since the compilers might generate buggy code.
//	go tool dist install cmd/compile
//
//	# Check that new tools behave identically to saved tools.
//	go build -toolexec 'toolstash -cmp' -a std
//
//	# If not, restore, in order to keep working on Go code.
//	toolstash restore
//
// # Version Skew
//
// The Go tools write the current Go version to object files, and (outside
// release branches) that version includes the hash and time stamp
// of the most recent Git commit. Functionally equivalent
// compilers built at different Git versions may produce object files that
// differ only in the recorded version. Toolstash ignores version mismatches
// when comparing object files, but the standard tools will refuse to compile
// or link together packages with different object versions.
//
// For the full build in the final example above to work, both the stashed
// and the installed tools must use the same version string.
// One way to ensure this is not to commit any of the changes being
// tested, so that the Git HEAD hash is the same for both builds.
// A more robust way to force the tools to have the same version string
// is to write a $GOROOT/VERSION file, which overrides the Git-based version
// computation:
//
//	echo devel >$GOROOT/VERSION
//
// The version can be arbitrary text, but to pass all.bash's API check, it must
// contain the substring “devel”. The VERSION file must be created before
// building either version of the toolchain.
package main // import "golang.org/x/tools/cmd/toolstash"

import (
	"bufio"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"time"
)

var usageMessage = `usage: toolstash [-n] [-v] [-cmp] command line

Examples:
	toolstash save
	toolstash restore
	toolstash go run x.go
	toolstash compile x.go
	toolstash -cmp compile x.go

For details, godoc golang.org/x/tools/cmd/toolstash
`

func usage() {
	fmt.Fprint(os.Stderr, usageMessage)
	os.Exit(2)
}

var (
	goCmd   = flag.String("go", "go", "path to \"go\" command")
	norun   = flag.Bool("n", false, "print but do not run commands")
	verbose = flag.Bool("v", false, "print commands being run")
	cmp     = flag.Bool("cmp", false, "compare tool object files")
	timing  = flag.Bool("t", false, "print time commands take")
)

var (
	cmd       []string
	tool      string // name of tool: "go", "compile", etc
	toolStash string // path to stashed tool

	goroot   string
	toolDir  string
	stashDir string
	binDir   string
)

func canCmp(name string, args []string) bool {
	switch name {
	case "asm", "compile", "link":
		if len(args) == 1 && (args[0] == "-V" || strings.HasPrefix(args[0], "-V=")) {
			// cmd/go uses "compile -V=full" to query the tool's build ID.
			return false
		}
		return true
	}
	return len(name) == 2 && '0' <= name[0] && name[0] <= '9' && (name[1] == 'a' || name[1] == 'g' || name[1] == 'l')
}

var binTools = []string{"go", "godoc", "gofmt"}

func isBinTool(name string) bool {
	return strings.HasPrefix(name, "go")
}

func main() {
	log.SetFlags(0)
	log.SetPrefix("toolstash: ")

	flag.Usage = usage
	flag.Parse()
	cmd = flag.Args()

	if len(cmd) < 1 {
		usage()
	}

	s, err := exec.Command(*goCmd, "env", "GOROOT").CombinedOutput()
	if err != nil {
		log.Fatalf("%s env GOROOT: %v", *goCmd, err)
	}
	goroot = strings.TrimSpace(string(s))
	toolDir = filepath.Join(goroot, fmt.Sprintf("pkg/tool/%s_%s", runtime.GOOS, runtime.GOARCH))
	stashDir = filepath.Join(goroot, "pkg/toolstash")

	binDir = os.Getenv("GOBIN")
	if binDir == "" {
		binDir = filepath.Join(goroot, "bin")
	}

	switch cmd[0] {
	case "save":
		save()
		return

	case "restore":
		restore()
		return
	}

	tool = exeName(cmd[0])
	if i := strings.LastIndexAny(tool, `/\`); i >= 0 {
		tool = tool[i+1:]
	}

	if !strings.HasPrefix(tool, "a.out") {
		toolStash = filepath.Join(stashDir, tool)
		if _, err := os.Stat(toolStash); err != nil {
			log.Print(err)
			os.Exit(2)
		}

		if *cmp && canCmp(tool, cmd[1:]) {
			compareTool()
			return
		}
		cmd[0] = toolStash
	}

	if *norun {
		fmt.Printf("%s\n", strings.Join(cmd, " "))
		return
	}
	if *verbose {
		log.Print(strings.Join(cmd, " "))
	}
	xcmd := exec.Command(cmd[0], cmd[1:]...)
	xcmd.Stdin = os.Stdin
	xcmd.Stdout = os.Stdout
	xcmd.Stderr = os.Stderr
	err = xcmd.Run()
	if err != nil {
		log.Fatal(err)
	}
	os.Exit(0)
}

func compareTool() {
	if !strings.Contains(cmd[0], "/") && !strings.Contains(cmd[0], `\`) {
		cmd[0] = filepath.Join(toolDir, tool)
	}

	outfile, ok := cmpRun(false, cmd)
	if ok {
		os.Remove(outfile + ".stash")
		return
	}

	extra := "-S=2"
	switch {
	default:
		log.Fatalf("unknown tool %s", tool)

	case tool == "compile" || strings.HasSuffix(tool, "g"): // compiler
		useDashN := true
		dashcIndex := -1
		for i, s := range cmd {
			if s == "-+" {
				// Compiling runtime. Don't use -N.
				useDashN = false
			}
			if strings.HasPrefix(s, "-c=") {
				dashcIndex = i
			}
		}
		cmdN := injectflags(cmd, nil, useDashN)
		_, ok := cmpRun(false, cmdN)
		if !ok {
			if useDashN {
				log.Printf("compiler output differs, with optimizers disabled (-N)")
			} else {
				log.Printf("compiler output differs")
			}
			if dashcIndex >= 0 {
				cmd[dashcIndex] = "-c=1"
			}
			cmd = injectflags(cmd, []string{"-v", "-m=2"}, useDashN)
			break
		}
		if dashcIndex >= 0 {
			cmd[dashcIndex] = "-c=1"
		}
		cmd = injectflags(cmd, []string{"-v", "-m=2"}, false)
		log.Printf("compiler output differs, only with optimizers enabled")

	case tool == "asm" || strings.HasSuffix(tool, "a"): // assembler
		log.Printf("assembler output differs")

	case tool == "link" || strings.HasSuffix(tool, "l"): // linker
		log.Printf("linker output differs")
		extra = "-v=2"
	}

	cmdS := injectflags(cmd, []string{extra}, false)
	outfile, _ = cmpRun(true, cmdS)

	fmt.Fprintf(os.Stderr, "\n%s\n", compareLogs(outfile))
	os.Exit(2)
}

func injectflags(cmd []string, extra []string, addDashN bool) []string {
	x := []string{cmd[0]}
	if addDashN {
		x = append(x, "-N")
	}
	x = append(x, extra...)
	x = append(x, cmd[1:]...)
	return x
}

func cmpRun(keepLog bool, cmd []string) (outfile string, match bool) {
	cmdStash := make([]string, len(cmd))
	copy(cmdStash, cmd)
	cmdStash[0] = toolStash
	for i, arg := range cmdStash {
		if arg == "-o" {
			outfile = cmdStash[i+1]
			cmdStash[i+1] += ".stash"
			break
		}
		if strings.HasSuffix(arg, ".s") || strings.HasSuffix(arg, ".go") && '0' <= tool[0] && tool[0] <= '9' {
			outfile = filepath.Base(arg[:strings.LastIndex(arg, ".")] + "." + tool[:1])
			cmdStash = append([]string{cmdStash[0], "-o", outfile + ".stash"}, cmdStash[1:]...)
			break
		}
	}

	if outfile == "" {
		log.Fatalf("cannot determine output file for command: %s", strings.Join(cmd, " "))
	}

	if *norun {
		fmt.Printf("%s\n", strings.Join(cmd, " "))
		fmt.Printf("%s\n", strings.Join(cmdStash, " "))
		os.Exit(0)
	}

	out, err := runCmd(cmd, keepLog, outfile+".log")
	if err != nil {
		log.Printf("running: %s", strings.Join(cmd, " "))
		os.Stderr.Write(out)
		log.Fatal(err)
	}

	outStash, err := runCmd(cmdStash, keepLog, outfile+".stash.log")
	if err != nil {
		log.Printf("running: %s", strings.Join(cmdStash, " "))
		log.Printf("installed tool succeeded but stashed tool failed.\n")
		if len(out) > 0 {
			log.Printf("installed tool output:")
			os.Stderr.Write(out)
		}
		if len(outStash) > 0 {
			log.Printf("stashed tool output:")
			os.Stderr.Write(outStash)
		}
		log.Fatal(err)
	}

	return outfile, sameObject(outfile, outfile+".stash")
}

func sameObject(file1, file2 string) bool {
	f1, err := os.Open(file1)
	if err != nil {
		log.Fatal(err)
	}
	defer f1.Close()

	f2, err := os.Open(file2)
	if err != nil {
		log.Fatal(err)
	}
	defer f2.Close()

	b1 := bufio.NewReader(f1)
	b2 := bufio.NewReader(f2)

	// Go object files and archives contain lines of the form
	//	go object <goos> <goarch> <version>
	// By default, the version on development branches includes
	// the Git hash and time stamp for the most recent commit.
	// We allow the versions to differ.
	if !skipVersion(b1, b2, file1, file2) {
		return false
	}

	lastByte := byte(0)
	for {
		c1, err1 := b1.ReadByte()
		c2, err2 := b2.ReadByte()
		if err1 == io.EOF && err2 == io.EOF {
			return true
		}
		if err1 != nil {
			log.Fatalf("reading %s: %v", file1, err1)
		}
		if err2 != nil {
			log.Fatalf("reading %s: %v", file2, err2)
		}
		if c1 != c2 {
			return false
		}
		if lastByte == '`' && c1 == '\n' {
			if !skipVersion(b1, b2, file1, file2) {
				return false
			}
		}
		lastByte = c1
	}
}

func skipVersion(b1, b2 *bufio.Reader, file1, file2 string) bool {
	// Consume "go object " prefix, if there.
	prefix := "go object "
	for i := 0; i < len(prefix); i++ {
		c1, err1 := b1.ReadByte()
		c2, err2 := b2.ReadByte()
		if err1 == io.EOF && err2 == io.EOF {
			return true
		}
		if err1 != nil {
			log.Fatalf("reading %s: %v", file1, err1)
		}
		if err2 != nil {
			log.Fatalf("reading %s: %v", file2, err2)
		}
		if c1 != c2 {
			return false
		}
		if c1 != prefix[i] {
			return true // matching bytes, just not a version
		}
	}

	// Keep comparing until second space.
	// Must continue to match.
	// If we see a \n, it's not a version string after all.
	for numSpace := 0; numSpace < 2; {
		c1, err1 := b1.ReadByte()
		c2, err2 := b2.ReadByte()
		if err1 == io.EOF && err2 == io.EOF {
			return true
		}
		if err1 != nil {
			log.Fatalf("reading %s: %v", file1, err1)
		}
		if err2 != nil {
			log.Fatalf("reading %s: %v", file2, err2)
		}
		if c1 != c2 {
			return false
		}
		if c1 == '\n' {
			return true
		}
		if c1 == ' ' {
			numSpace++
		}
	}

	// Have now seen 'go object goos goarch ' in both files.
	// Now they're allowed to diverge, until the \n, which
	// must be present.
	for {
		c1, err1 := b1.ReadByte()
		if err1 == io.EOF {
			log.Fatalf("reading %s: unexpected EOF", file1)
		}
		if err1 != nil {
			log.Fatalf("reading %s: %v", file1, err1)
		}
		if c1 == '\n' {
			break
		}
	}
	for {
		c2, err2 := b2.ReadByte()
		if err2 == io.EOF {
			log.Fatalf("reading %s: unexpected EOF", file2)
		}
		if err2 != nil {
			log.Fatalf("reading %s: %v", file2, err2)
		}
		if c2 == '\n' {
			break
		}
	}

	// Consumed "matching" versions from both.
	return true
}

func runCmd(cmd []string, keepLog bool, logName string) (output []byte, err error) {
	if *verbose {
		log.Print(strings.Join(cmd, " "))
	}

	if *timing {
		t0 := time.Now()
		defer func() {
			log.Printf("%.3fs elapsed # %s\n", time.Since(t0).Seconds(), strings.Join(cmd, " "))
		}()
	}

	xcmd := exec.Command(exeName(cmd[0]), cmd[1:]...)
	if !keepLog {
		return xcmd.CombinedOutput()
	}

	f, err := os.Create(logName)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Fprintf(f, "GOOS=%s GOARCH=%s %s\n", os.Getenv("GOOS"), os.Getenv("GOARCH"), strings.Join(cmd, " "))
	xcmd.Stdout = f
	xcmd.Stderr = f
	defer f.Close()
	return nil, xcmd.Run()
}

func save() {
	if err := os.MkdirAll(stashDir, 0777); err != nil {
		log.Fatal(err)
	}

	toolDir := filepath.Join(goroot, fmt.Sprintf("pkg/tool/%s_%s", runtime.GOOS, runtime.GOARCH))
	files, err := os.ReadDir(toolDir)
	if err != nil {
		log.Fatal(err)
	}

	for _, file := range files {
		info, err := file.Info()
		if err != nil {
			log.Fatal(err)
		}
		if shouldSave(file.Name()) && info.Mode().IsRegular() {
			cp(filepath.Join(toolDir, file.Name()), filepath.Join(stashDir, file.Name()))
		}
	}

	for _, name := range binTools {
		if !shouldSave(name) {
			continue
		}
		bin := exeName(name)
		src := filepath.Join(binDir, bin)
		if _, err := os.Stat(src); err == nil {
			cp(src, filepath.Join(stashDir, bin))
		}
	}

	checkShouldSave()
}

func restore() {
	files, err := os.ReadDir(stashDir)
	if err != nil {
		log.Fatal(err)
	}

	for _, file := range files {
		info, err := file.Info()
		if err != nil {
			log.Fatal(err)
		}
		if shouldSave(file.Name()) && info.Mode().IsRegular() {
			targ := toolDir
			if isBinTool(file.Name()) {
				targ = binDir
			}
			cp(filepath.Join(stashDir, file.Name()), filepath.Join(targ, file.Name()))
		}
	}

	checkShouldSave()
}

func shouldSave(name string) bool {
	if len(cmd) == 1 {
		return true
	}
	ok := false
	for i, arg := range cmd {
		if i > 0 && name == arg {
			ok = true
			cmd[i] = "DONE"
		}
	}
	return ok
}

func checkShouldSave() {
	var missing []string
	for _, arg := range cmd[1:] {
		if arg != "DONE" {
			missing = append(missing, arg)
		}
	}
	if len(missing) > 0 {
		log.Fatalf("%s did not find tools: %s", cmd[0], strings.Join(missing, " "))
	}
}

func cp(src, dst string) {
	if *verbose {
		fmt.Printf("cp %s %s\n", src, dst)
	}
	data, err := os.ReadFile(src)
	if err != nil {
		log.Fatal(err)
	}
	if err := os.WriteFile(dst, data, 0777); err != nil {
		log.Fatal(err)
	}
}

func exeName(name string) string {
	if runtime.GOOS == "windows" {
		return name + ".exe"
	}
	return name
}


================================================
FILE: codereview.cfg
================================================
issuerepo: golang/go


================================================
FILE: container/intsets/export_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package intsets

// Backdoor for testing.
func (s *Sparse) Check() error { return s.check() }


================================================
FILE: container/intsets/sparse.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package intsets provides Sparse, a compact and fast representation
// for sparse sets of int values.
//
// The time complexity of the operations Len, Insert, Remove and Has
// is in O(n) but in practice those methods are faster and more
// space-efficient than equivalent operations on sets based on the Go
// map type.  The IsEmpty, Min, Max, Clear and TakeMin operations
// require constant time.
package intsets // import "golang.org/x/tools/container/intsets"

// TODO(adonovan):
// - Add InsertAll(...int), RemoveAll(...int)
// - Add 'bool changed' results for {Intersection,Difference}With too.
//
// TODO(adonovan): implement Dense, a dense bit vector with a similar API.
// The space usage would be proportional to Max(), not Len(), and the
// implementation would be based upon big.Int.
//
// TODO(adonovan): opt: make UnionWith and Difference faster.
// These are the hot-spots for go/pointer.

import (
	"bytes"
	"fmt"
	"math/bits"
)

// A Sparse is a set of int values.
// Sparse operations (even queries) are not concurrency-safe.
//
// The zero value for Sparse is a valid empty set.
//
// Sparse sets must be copied using the Copy method, not by assigning
// a Sparse value.
type Sparse struct {
	// An uninitialized Sparse represents an empty set.
	// An empty set may also be represented by
	//  root.next == root.prev == &root.
	//
	// The root is always the block with the smallest offset.
	// It can be empty, but only if it is the only block; in that case, offset is
	// MaxInt (which is not a valid offset).
	root block
}

type word uintptr

const (
	_m            = ^word(0)
	bitsPerWord   = 8 << (_m>>8&1 + _m>>16&1 + _m>>32&1)
	bitsPerBlock  = 256 // optimal value for go/pointer solver performance
	wordsPerBlock = bitsPerBlock / bitsPerWord
)

// Limit values of implementation-specific int type.
const (
	MaxInt = int(^uint(0) >> 1)
	MinInt = -MaxInt - 1
)

// popcount returns the number of set bits in w.
func popcount(x word) int {
	// Avoid OnesCount(uint): don't assume uint = uintptr.
	if bitsPerWord == 32 {
		return bits.OnesCount32(uint32(x))
	} else {
		return bits.OnesCount64(uint64(x))
	}
}

// nlz returns the number of leading zeros of x.
func nlz(x word) int {
	// Avoid LeadingZeros(uint): don't assume uint = uintptr.
	if bitsPerWord == 32 {
		return bits.LeadingZeros32(uint32(x))
	} else {
		return bits.LeadingZeros64(uint64(x))
	}
}

// ntz returns the number of trailing zeros of x.
func ntz(x word) int {
	// Avoid TrailingZeros(uint): don't assume uint = uintptr.
	if bitsPerWord == 32 {
		return bits.TrailingZeros32(uint32(x))
	} else {
		return bits.TrailingZeros64(uint64(x))
	}
}

// -- block ------------------------------------------------------------

// A set is represented as a circular doubly-linked list of blocks,
// each containing an offset and a bit array of fixed size
// bitsPerBlock; the blocks are ordered by increasing offset.
//
// The set contains an element x iff the block whose offset is x - (x
// mod bitsPerBlock) has the bit (x mod bitsPerBlock) set, where mod
// is the Euclidean remainder.
//
// A block may only be empty transiently.
type block struct {
	offset     int                 // offset mod bitsPerBlock == 0
	bits       [wordsPerBlock]word // contains at least one set bit
	next, prev *block              // doubly-linked list of blocks
}

// wordMask returns the word index (in block.bits)
// and single-bit mask for the block's ith bit.
func wordMask(i uint) (w uint, mask word) {
	w = i / bitsPerWord
	mask = 1 << (i % bitsPerWord)
	return
}

// insert sets the block b's ith bit and
// returns true if it was not already set.
func (b *block) insert(i uint) bool {
	w, mask := wordMask(i)
	if b.bits[w]&mask == 0 {
		b.bits[w] |= mask
		return true
	}
	return false
}

// remove clears the block's ith bit and
// returns true if the bit was previously set.
// NB: may leave the block empty.
func (b *block) remove(i uint) bool {
	w, mask := wordMask(i)
	if b.bits[w]&mask != 0 {
		b.bits[w] &^= mask
		return true
	}
	return false
}

// has reports whether the block's ith bit is set.
func (b *block) has(i uint) bool {
	w, mask := wordMask(i)
	return b.bits[w]&mask != 0
}

// empty reports whether b.len()==0, but more efficiently.
func (b *block) empty() bool {
	for _, w := range b.bits {
		if w != 0 {
			return false
		}
	}
	return true
}

// len returns the number of set bits in block b.
func (b *block) len() int {
	var l int
	for _, w := range b.bits {
		l += popcount(w)
	}
	return l
}

// max returns the maximum element of the block.
// The block must not be empty.
func (b *block) max() int {
	bi := b.offset + bitsPerBlock
	// Decrement bi by number of high zeros in last.bits.
	for i := len(b.bits) - 1; i >= 0; i-- {
		if w := b.bits[i]; w != 0 {
			return bi - nlz(w) - 1
		}
		bi -= bitsPerWord
	}
	panic("BUG: empty block")
}

// min returns the minimum element of the block,
// and also removes it if take is set.
// The block must not be initially empty.
// NB: may leave the block empty.
func (b *block) min(take bool) int {
	for i, w := range b.bits {
		if w != 0 {
			tz := ntz(w)
			if take {
				b.bits[i] = w &^ (1 << uint(tz))
			}
			return b.offset + i*bitsPerWord + tz
		}
	}
	panic("BUG: empty block")
}

// lowerBound returns the smallest element of the block that is greater than or
// equal to the element corresponding to the ith bit. If there is no such
// element, the second return value is false.
func (b *block) lowerBound(i uint) (int, bool) {
	w := i / bitsPerWord
	bit := i % bitsPerWord

	if val := b.bits[w] >> bit; val != 0 {
		return b.offset + int(i) + ntz(val), true
	}

	for w++; w < wordsPerBlock; w++ {
		if val := b.bits[w]; val != 0 {
			return b.offset + int(w*bitsPerWord) + ntz(val), true
		}
	}

	return 0, false
}

// forEach calls f for each element of block b.
// f must not mutate b's enclosing Sparse.
func (b *block) forEach(f func(int)) {
	for i, w := range b.bits {
		offset := b.offset + i*bitsPerWord
		for bi := 0; w != 0 && bi < bitsPerWord; bi++ {
			if w&1 != 0 {
				f(offset)
			}
			offset++
			w >>= 1
		}
	}
}

// offsetAndBitIndex returns the offset of the block that would
// contain x and the bit index of x within that block.
func offsetAndBitIndex(x int) (int, uint) {
	mod := x % bitsPerBlock
	if mod < 0 {
		// Euclidean (non-negative) remainder
		mod += bitsPerBlock
	}
	return x - mod, uint(mod)
}

// -- Sparse --------------------------------------------------------------

// none is a shared, empty, sentinel block that indicates the end of a block
// list.
var none block

// Dummy type used to generate an implicit panic. This must be defined at the
// package level; if it is defined inside a function, it prevents the inlining
// of that function.
type to_copy_a_sparse_you_must_call_its_Copy_method struct{}

// init ensures s is properly initialized.
func (s *Sparse) init() {
	root := &s.root
	if root.next == nil {
		root.offset = MaxInt
		root.next = root
		root.prev = root
	} else if root.next.prev != root {
		// Copying a Sparse x leads to pernicious corruption: the
		// new Sparse y shares the old linked list, but iteration
		// on y will never encounter &y.root so it goes into a
		// loop.  Fail fast before this occurs.
		// We don't want to call panic here because it prevents the
		// inlining of this function.
		_ = (any(nil)).(to_copy_a_sparse_you_must_call_its_Copy_method)
	}
}

func (s *Sparse) first() *block {
	s.init()
	if s.root.offset == MaxInt {
		return &none
	}
	return &s.root
}

// next returns the next block in the list, or end if b is the last block.
func (s *Sparse) next(b *block) *block {
	if b.next == &s.root {
		return &none
	}
	return b.next
}

// IsEmpty reports whether the set s is empty.
func (s *Sparse) IsEmpty() bool {
	return s.root.next == nil || s.root.offset == MaxInt
}

// Len returns the number of elements in the set s.
func (s *Sparse) Len() int {
	var l int
	for b := s.first(); b != &none; b = s.next(b) {
		l += b.len()
	}
	return l
}

// Max returns the maximum element of the set s, or MinInt if s is empty.
func (s *Sparse) Max() int {
	if s.IsEmpty() {
		return MinInt
	}
	return s.root.prev.max()
}

// Min returns the minimum element of the set s, or MaxInt if s is empty.
func (s *Sparse) Min() int {
	if s.IsEmpty() {
		return MaxInt
	}
	return s.root.min(false)
}

// LowerBound returns the smallest element >= x, or MaxInt if there is no such
// element.
func (s *Sparse) LowerBound(x int) int {
	offset, i := offsetAndBitIndex(x)
	for b := s.first(); b != &none; b = s.next(b) {
		if b.offset > offset {
			return b.min(false)
		}
		if b.offset == offset {
			if y, ok := b.lowerBound(i); ok {
				return y
			}
		}
	}
	return MaxInt
}

// block returns the block that would contain offset,
// or nil if s contains no such block.
// Precondition: offset is a multiple of bitsPerBlock.
func (s *Sparse) block(offset int) *block {
	for b := s.first(); b != &none && b.offset <= offset; b = s.next(b) {
		if b.offset == offset {
			return b
		}
	}
	return nil
}

// Insert adds x to the set s, and reports whether the set grew.
func (s *Sparse) Insert(x int) bool {
	offset, i := offsetAndBitIndex(x)

	b := s.first()
	for ; b != &none && b.offset <= offset; b = s.next(b) {
		if b.offset == offset {
			return b.insert(i)
		}
	}

	// Insert new block before b.
	new := s.insertBlockBefore(b)
	new.offset = offset
	return new.insert(i)
}

// removeBlock removes a block and returns the block that followed it (or end if
// it was the last block).
func (s *Sparse) removeBlock(b *block) *block {
	if b != &s.root {
		b.prev.next = b.next
		b.next.prev = b.prev
		if b.next == &s.root {
			return &none
		}
		return b.next
	}

	first := s.root.next
	if first == &s.root {
		// This was the only block.
		s.Clear()
		return &none
	}
	s.root.offset = first.offset
	s.root.bits = first.bits
	if first.next == &s.root {
		// Single block remaining.
		s.root.next = &s.root
		s.root.prev = &s.root
	} else {
		s.root.next = first.next
		first.next.prev = &s.root
	}
	return &s.root
}

// Remove removes x from the set s, and reports whether the set shrank.
func (s *Sparse) Remove(x int) bool {
	offset, i := offsetAndBitIndex(x)
	if b := s.block(offset); b != nil {
		if !b.remove(i) {
			return false
		}
		if b.empty() {
			s.removeBlock(b)
		}
		return true
	}
	return false
}

// Clear removes all elements from the set s.
func (s *Sparse) Clear() {
	s.root = block{
		offset: MaxInt,
		next:   &s.root,
		prev:   &s.root,
	}
}

// If set s is non-empty, TakeMin sets *p to the minimum element of
// the set s, removes that element from the set and returns true.
// Otherwise, it returns false and *p is undefined.
//
// This method may be used for iteration over a worklist like so:
//
//	var x int
//	for worklist.TakeMin(&x) { use(x) }
func (s *Sparse) TakeMin(p *int) bool {
	if s.IsEmpty() {
		return false
	}
	*p = s.root.min(true)
	if s.root.empty() {
		s.removeBlock(&s.root)
	}
	return true
}

// Has reports whether x is an element of the set s.
func (s *Sparse) Has(x int) bool {
	offset, i := offsetAndBitIndex(x)
	if b := s.block(offset); b != nil {
		return b.has(i)
	}
	return false
}

// forEach applies function f to each element of the set s in order.
//
// f must not mutate s.  Consequently, forEach is not safe to expose
// to clients.  In any case, using "range s.AppendTo()" allows more
// natural control flow with continue/break/return.
func (s *Sparse) forEach(f func(int)) {
	for b := s.first(); b != &none; b = s.next(b) {
		b.forEach(f)
	}
}

// Copy sets s to the value of x.
func (s *Sparse) Copy(x *Sparse) {
	if s == x {
		return
	}

	xb := x.first()
	sb := s.first()
	for xb != &none {
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = xb.offset
		sb.bits = xb.bits
		xb = x.next(xb)
		sb = s.next(sb)
	}
	s.discardTail(sb)
}

// insertBlockBefore returns a new block, inserting it before next.
// If next is the root, the root is replaced. If next is end, the block is
// inserted at the end.
func (s *Sparse) insertBlockBefore(next *block) *block {
	if s.IsEmpty() {
		if next != &none {
			panic("BUG: passed block with empty set")
		}
		return &s.root
	}

	if next == &s.root {
		// Special case: we need to create a new block that will become the root
		// block.The old root block becomes the second block.
		second := s.root
		s.root = block{
			next: &second,
		}
		if second.next == &s.root {
			s.root.prev = &second
		} else {
			s.root.prev = second.prev
			second.next.prev = &second
			second.prev = &s.root
		}
		return &s.root
	}
	if next == &none {
		// Insert before root.
		next = &s.root
	}
	b := new(block)
	b.next = next
	b.prev = next.prev
	b.prev.next = b
	next.prev = b
	return b
}

// discardTail removes block b and all its successors from s.
func (s *Sparse) discardTail(b *block) {
	if b != &none {
		if b == &s.root {
			s.Clear()
		} else {
			b.prev.next = &s.root
			s.root.prev = b.prev
		}
	}
}

// IntersectionWith sets s to the intersection s ∩ x.
func (s *Sparse) IntersectionWith(x *Sparse) {
	if s == x {
		return
	}

	xb := x.first()
	sb := s.first()
	for xb != &none && sb != &none {
		switch {
		case xb.offset < sb.offset:
			xb = x.next(xb)

		case xb.offset > sb.offset:
			sb = s.removeBlock(sb)

		default:
			var sum word
			for i := range sb.bits {
				r := xb.bits[i] & sb.bits[i]
				sb.bits[i] = r
				sum |= r
			}
			if sum != 0 {
				sb = s.next(sb)
			} else {
				// sb will be overwritten or removed
			}

			xb = x.next(xb)
		}
	}

	s.discardTail(sb)
}

// Intersection sets s to the intersection x ∩ y.
func (s *Sparse) Intersection(x, y *Sparse) {
	switch {
	case s == x:
		s.IntersectionWith(y)
		return
	case s == y:
		s.IntersectionWith(x)
		return
	case x == y:
		s.Copy(x)
		return
	}

	xb := x.first()
	yb := y.first()
	sb := s.first()
	for xb != &none && yb != &none {
		switch {
		case xb.offset < yb.offset:
			xb = x.next(xb)
			continue
		case xb.offset > yb.offset:
			yb = y.next(yb)
			continue
		}

		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = xb.offset

		var sum word
		for i := range sb.bits {
			r := xb.bits[i] & yb.bits[i]
			sb.bits[i] = r
			sum |= r
		}
		if sum != 0 {
			sb = s.next(sb)
		} else {
			// sb will be overwritten or removed
		}

		xb = x.next(xb)
		yb = y.next(yb)
	}

	s.discardTail(sb)
}

// Intersects reports whether s ∩ x ≠ ∅.
func (s *Sparse) Intersects(x *Sparse) bool {
	sb := s.first()
	xb := x.first()
	for sb != &none && xb != &none {
		switch {
		case xb.offset < sb.offset:
			xb = x.next(xb)
		case xb.offset > sb.offset:
			sb = s.next(sb)
		default:
			for i := range sb.bits {
				if sb.bits[i]&xb.bits[i] != 0 {
					return true
				}
			}
			sb = s.next(sb)
			xb = x.next(xb)
		}
	}
	return false
}

// UnionWith sets s to the union s ∪ x, and reports whether s grew.
func (s *Sparse) UnionWith(x *Sparse) bool {
	if s == x {
		return false
	}

	var changed bool
	xb := x.first()
	sb := s.first()
	for xb != &none {
		if sb != &none && sb.offset == xb.offset {
			for i := range xb.bits {
				union := sb.bits[i] | xb.bits[i]
				if sb.bits[i] != union {
					sb.bits[i] = union
					changed = true
				}
			}
			xb = x.next(xb)
		} else if sb == &none || sb.offset > xb.offset {
			sb = s.insertBlockBefore(sb)
			sb.offset = xb.offset
			sb.bits = xb.bits
			changed = true

			xb = x.next(xb)
		}
		sb = s.next(sb)
	}
	return changed
}

// Union sets s to the union x ∪ y.
func (s *Sparse) Union(x, y *Sparse) {
	switch {
	case x == y:
		s.Copy(x)
		return
	case s == x:
		s.UnionWith(y)
		return
	case s == y:
		s.UnionWith(x)
		return
	}

	xb := x.first()
	yb := y.first()
	sb := s.first()
	for xb != &none || yb != &none {
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		switch {
		case yb == &none || (xb != &none && xb.offset < yb.offset):
			sb.offset = xb.offset
			sb.bits = xb.bits
			xb = x.next(xb)

		case xb == &none || (yb != &none && yb.offset < xb.offset):
			sb.offset = yb.offset
			sb.bits = yb.bits
			yb = y.next(yb)

		default:
			sb.offset = xb.offset
			for i := range xb.bits {
				sb.bits[i] = xb.bits[i] | yb.bits[i]
			}
			xb = x.next(xb)
			yb = y.next(yb)
		}
		sb = s.next(sb)
	}

	s.discardTail(sb)
}

// DifferenceWith sets s to the difference s ∖ x.
func (s *Sparse) DifferenceWith(x *Sparse) {
	if s == x {
		s.Clear()
		return
	}

	xb := x.first()
	sb := s.first()
	for xb != &none && sb != &none {
		switch {
		case xb.offset > sb.offset:
			sb = s.next(sb)

		case xb.offset < sb.offset:
			xb = x.next(xb)

		default:
			var sum word
			for i := range sb.bits {
				r := sb.bits[i] & ^xb.bits[i]
				sb.bits[i] = r
				sum |= r
			}
			if sum == 0 {
				sb = s.removeBlock(sb)
			} else {
				sb = s.next(sb)
			}
			xb = x.next(xb)
		}
	}
}

// Difference sets s to the difference x ∖ y.
func (s *Sparse) Difference(x, y *Sparse) {
	switch {
	case x == y:
		s.Clear()
		return
	case s == x:
		s.DifferenceWith(y)
		return
	case s == y:
		var y2 Sparse
		y2.Copy(y)
		s.Difference(x, &y2)
		return
	}

	xb := x.first()
	yb := y.first()
	sb := s.first()
	for xb != &none && yb != &none {
		if xb.offset > yb.offset {
			// y has block, x has &none
			yb = y.next(yb)
			continue
		}

		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = xb.offset

		switch {
		case xb.offset < yb.offset:
			// x has block, y has &none
			sb.bits = xb.bits

			sb = s.next(sb)

		default:
			// x and y have corresponding blocks
			var sum word
			for i := range sb.bits {
				r := xb.bits[i] & ^yb.bits[i]
				sb.bits[i] = r
				sum |= r
			}
			if sum != 0 {
				sb = s.next(sb)
			} else {
				// sb will be overwritten or removed
			}

			yb = y.next(yb)
		}
		xb = x.next(xb)
	}

	for xb != &none {
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = xb.offset
		sb.bits = xb.bits
		sb = s.next(sb)

		xb = x.next(xb)
	}

	s.discardTail(sb)
}

// SymmetricDifferenceWith sets s to the symmetric difference s ∆ x.
func (s *Sparse) SymmetricDifferenceWith(x *Sparse) {
	if s == x {
		s.Clear()
		return
	}

	sb := s.first()
	xb := x.first()
	for xb != &none && sb != &none {
		switch {
		case sb.offset < xb.offset:
			sb = s.next(sb)
		case xb.offset < sb.offset:
			nb := s.insertBlockBefore(sb)
			nb.offset = xb.offset
			nb.bits = xb.bits
			xb = x.next(xb)
		default:
			var sum word
			for i := range sb.bits {
				r := sb.bits[i] ^ xb.bits[i]
				sb.bits[i] = r
				sum |= r
			}
			if sum == 0 {
				sb = s.removeBlock(sb)
			} else {
				sb = s.next(sb)
			}
			xb = x.next(xb)
		}
	}

	for xb != &none { // append the tail of x to s
		sb = s.insertBlockBefore(sb)
		sb.offset = xb.offset
		sb.bits = xb.bits
		sb = s.next(sb)
		xb = x.next(xb)
	}
}

// SymmetricDifference sets s to the symmetric difference x ∆ y.
func (s *Sparse) SymmetricDifference(x, y *Sparse) {
	switch {
	case x == y:
		s.Clear()
		return
	case s == x:
		s.SymmetricDifferenceWith(y)
		return
	case s == y:
		s.SymmetricDifferenceWith(x)
		return
	}

	sb := s.first()
	xb := x.first()
	yb := y.first()
	for xb != &none && yb != &none {
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		switch {
		case yb.offset < xb.offset:
			sb.offset = yb.offset
			sb.bits = yb.bits
			sb = s.next(sb)
			yb = y.next(yb)
		case xb.offset < yb.offset:
			sb.offset = xb.offset
			sb.bits = xb.bits
			sb = s.next(sb)
			xb = x.next(xb)
		default:
			var sum word
			for i := range sb.bits {
				r := xb.bits[i] ^ yb.bits[i]
				sb.bits[i] = r
				sum |= r
			}
			if sum != 0 {
				sb.offset = xb.offset
				sb = s.next(sb)
			}
			xb = x.next(xb)
			yb = y.next(yb)
		}
	}

	for xb != &none { // append the tail of x to s
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = xb.offset
		sb.bits = xb.bits
		sb = s.next(sb)
		xb = x.next(xb)
	}

	for yb != &none { // append the tail of y to s
		if sb == &none {
			sb = s.insertBlockBefore(sb)
		}
		sb.offset = yb.offset
		sb.bits = yb.bits
		sb = s.next(sb)
		yb = y.next(yb)
	}

	s.discardTail(sb)
}

// SubsetOf reports whether s ∖ x = ∅.
func (s *Sparse) SubsetOf(x *Sparse) bool {
	if s == x {
		return true
	}

	sb := s.first()
	xb := x.first()
	for sb != &none {
		switch {
		case xb == &none || xb.offset > sb.offset:
			return false
		case xb.offset < sb.offset:
			xb = x.next(xb)
		default:
			for i := range sb.bits {
				if sb.bits[i]&^xb.bits[i] != 0 {
					return false
				}
			}
			sb = s.next(sb)
			xb = x.next(xb)
		}
	}
	return true
}

// Equals reports whether the sets s and t have the same elements.
func (s *Sparse) Equals(t *Sparse) bool {
	if s == t {
		return true
	}
	sb := s.first()
	tb := t.first()
	for {
		switch {
		case sb == &none && tb == &none:
			return true
		case sb == &none || tb == &none:
			return false
		case sb.offset != tb.offset:
			return false
		case sb.bits != tb.bits:
			return false
		}

		sb = s.next(sb)
		tb = t.next(tb)
	}
}

// String returns a human-readable description of the set s.
func (s *Sparse) String() string {
	var buf bytes.Buffer
	buf.WriteByte('{')
	s.forEach(func(x int) {
		if buf.Len() > 1 {
			buf.WriteByte(' ')
		}
		fmt.Fprintf(&buf, "%d", x)
	})
	buf.WriteByte('}')
	return buf.String()
}

// BitString returns the set as a string of 1s and 0s denoting the sum
// of the i'th powers of 2, for each i in s.  A radix point, always
// preceded by a digit, appears if the sum is non-integral.
//
// Examples:
//
//	        {}.BitString() =      "0"
//	     {4,5}.BitString() = "110000"
//	      {-3}.BitString() =      "0.001"
//	{-3,0,4,5}.BitString() = "110001.001"
func (s *Sparse) BitString() string {
	if s.IsEmpty() {
		return "0"
	}

	min, max := s.Min(), s.Max()
	var nbytes int
	if max > 0 {
		nbytes = max
	}
	nbytes++ // zero bit
	radix := nbytes
	if min < 0 {
		nbytes += len(".") - min
	}

	b := make([]byte, nbytes)
	for i := range b {
		b[i] = '0'
	}
	if radix < nbytes {
		b[radix] = '.'
	}
	s.forEach(func(x int) {
		if x >= 0 {
			x += len(".")
		}
		b[radix-x] = '1'
	})
	return string(b)
}

// GoString returns a string showing the internal representation of
// the set s.
func (s *Sparse) GoString() string {
	var buf bytes.Buffer
	for b := s.first(); b != &none; b = s.next(b) {
		fmt.Fprintf(&buf, "block %p {offset=%d next=%p prev=%p",
			b, b.offset, b.next, b.prev)
		for _, w := range b.bits {
			fmt.Fprintf(&buf, " 0%016x", w)
		}
		fmt.Fprintf(&buf, "}\n")
	}
	return buf.String()
}

// AppendTo returns the result of appending the elements of s to slice
// in order.
func (s *Sparse) AppendTo(slice []int) []int {
	s.forEach(func(x int) {
		slice = append(slice, x)
	})
	return slice
}

// -- Testing/debugging ------------------------------------------------

// check returns an error if the representation invariants of s are violated.
// (unused; retained for debugging)
func (s *Sparse) check() error {
	s.init()
	if s.root.empty() {
		// An empty set must have only the root block with offset MaxInt.
		if s.root.next != &s.root {
			return fmt.Errorf("multiple blocks with empty root block")
		}
		if s.root.offset != MaxInt {
			return fmt.Errorf("empty set has offset %d, should be MaxInt", s.root.offset)
		}
		return nil
	}
	for b := s.first(); ; b = s.next(b) {
		if b.offset%bitsPerBlock != 0 {
			return fmt.Errorf("bad offset modulo: %d", b.offset)
		}
		if b.empty() {
			return fmt.Errorf("empty block")
		}
		if b.prev.next != b {
			return fmt.Errorf("bad prev.next link")
		}
		if b.next.prev != b {
			return fmt.Errorf("bad next.prev link")
		}
		if b.next == &s.root {
			break
		}
		if b.offset >= b.next.offset {
			return fmt.Errorf("bad offset order: b.offset=%d, b.next.offset=%d",
				b.offset, b.next.offset)
		}
	}
	return nil
}


================================================
FILE: container/intsets/sparse_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package intsets_test

import (
	"fmt"
	"log"
	"math/rand"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/container/intsets"
)

func TestBasics(t *testing.T) {
	var s intsets.Sparse
	if len := s.Len(); len != 0 {
		t.Errorf("Len({}): got %d, want 0", len)
	}
	if s := s.String(); s != "{}" {
		t.Errorf("String({}): got %q, want \"{}\"", s)
	}
	if s.Has(3) {
		t.Errorf("Has(3): got true, want false")
	}
	if err := s.Check(); err != nil {
		t.Error(err)
	}

	if !s.Insert(3) {
		t.Errorf("Insert(3): got false, want true")
	}
	if max := s.Max(); max != 3 {
		t.Errorf("Max: got %d, want 3", max)
	}

	if !s.Insert(435) {
		t.Errorf("Insert(435): got false, want true")
	}
	if s := s.String(); s != "{3 435}" {
		t.Errorf("String({3 435}): got %q, want \"{3 435}\"", s)
	}
	if max := s.Max(); max != 435 {
		t.Errorf("Max: got %d, want 435", max)
	}
	if len := s.Len(); len != 2 {
		t.Errorf("Len: got %d, want 2", len)
	}

	if !s.Remove(435) {
		t.Errorf("Remove(435): got false, want true")
	}
	if s := s.String(); s != "{3}" {
		t.Errorf("String({3}): got %q, want \"{3}\"", s)
	}
}

// Insert, Len, IsEmpty, Hash, Clear, AppendTo.
func TestMoreBasics(t *testing.T) {
	set := new(intsets.Sparse)
	set.Insert(456)
	set.Insert(123)
	set.Insert(789)
	if set.Len() != 3 {
		t.Errorf("%s.Len: got %d, want 3", set, set.Len())
	}
	if set.IsEmpty() {
		t.Errorf("%s.IsEmpty: got true", set)
	}
	if !set.Has(123) {
		t.Errorf("%s.Has(123): got false", set)
	}
	if set.Has(1234) {
		t.Errorf("%s.Has(1234): got true", set)
	}
	got := set.AppendTo([]int{-1})
	if want := []int{-1, 123, 456, 789}; fmt.Sprint(got) != fmt.Sprint(want) {
		t.Errorf("%s.AppendTo: got %v, want %v", set, got, want)
	}

	set.Clear()

	if set.Len() != 0 {
		t.Errorf("Clear: got %d, want 0", set.Len())
	}
	if !set.IsEmpty() {
		t.Errorf("IsEmpty: got false")
	}
	if set.Has(123) {
		t.Errorf("%s.Has: got false", set)
	}
}

func TestTakeMin(t *testing.T) {
	var set intsets.Sparse
	set.Insert(456)
	set.Insert(123)
	set.Insert(789)
	set.Insert(-123)
	var got int
	for i, want := range []int{-123, 123, 456, 789} {
		if !set.TakeMin(&got) || got != want {
			t.Errorf("TakeMin #%d: got %d, want %d", i, got, want)
		}
	}
	if set.TakeMin(&got) {
		t.Errorf("%s.TakeMin returned true", &set)
	}
	if err := set.Check(); err != nil {
		t.Fatalf("check: %s: %#v", err, &set)
	}
}

func TestMinAndMax(t *testing.T) {
	values := []int{0, 456, 123, 789, -123} // elt 0 => empty set
	wantMax := []int{intsets.MinInt, 456, 456, 789, 789}
	wantMin := []int{intsets.MaxInt, 456, 123, 123, -123}

	var set intsets.Sparse
	for i, x := range values {
		if i != 0 {
			set.Insert(x)
		}
		if got, want := set.Min(), wantMin[i]; got != want {
			t.Errorf("Min #%d: got %d, want %d", i, got, want)
		}
		if got, want := set.Max(), wantMax[i]; got != want {
			t.Errorf("Max #%d: got %d, want %d", i, got, want)
		}
	}

	set.Insert(intsets.MinInt)
	if got, want := set.Min(), intsets.MinInt; got != want {
		t.Errorf("Min: got %d, want %d", got, want)
	}

	set.Insert(intsets.MaxInt)
	if got, want := set.Max(), intsets.MaxInt; got != want {
		t.Errorf("Max: got %d, want %d", got, want)
	}
}

func TestEquals(t *testing.T) {
	var setX intsets.Sparse
	setX.Insert(456)
	setX.Insert(123)
	setX.Insert(789)

	if !setX.Equals(&setX) {
		t.Errorf("Equals(%s, %s): got false", &setX, &setX)
	}

	var setY intsets.Sparse
	setY.Insert(789)
	setY.Insert(456)
	setY.Insert(123)

	if !setX.Equals(&setY) {
		t.Errorf("Equals(%s, %s): got false", &setX, &setY)
	}

	setY.Insert(1)
	if setX.Equals(&setY) {
		t.Errorf("Equals(%s, %s): got true", &setX, &setY)
	}

	var empty intsets.Sparse
	if setX.Equals(&empty) {
		t.Errorf("Equals(%s, %s): got true", &setX, &empty)
	}

	// Edge case: some block (with offset=0) appears in X but not Y.
	setY.Remove(123)
	if setX.Equals(&setY) {
		t.Errorf("Equals(%s, %s): got true", &setX, &setY)
	}
}

// A pset is a parallel implementation of a set using both an intsets.Sparse
// and a built-in hash map.
type pset struct {
	hash map[int]bool
	bits intsets.Sparse
}

func makePset() *pset {
	return &pset{hash: make(map[int]bool)}
}

func (set *pset) add(n int) {
	prev := len(set.hash)
	set.hash[n] = true
	grewA := len(set.hash) > prev

	grewB := set.bits.Insert(n)

	if grewA != grewB {
		panic(fmt.Sprintf("add(%d): grewA=%t grewB=%t", n, grewA, grewB))
	}
}

func (set *pset) remove(n int) {
	prev := len(set.hash)
	delete(set.hash, n)
	shrankA := len(set.hash) < prev

	shrankB := set.bits.Remove(n)

	if shrankA != shrankB {
		panic(fmt.Sprintf("remove(%d): shrankA=%t shrankB=%t", n, shrankA, shrankB))
	}
}

func (set *pset) check(t *testing.T, msg string) {
	var eltsA []int
	for elt := range set.hash {
		eltsA = append(eltsA, int(elt))
	}
	sort.Ints(eltsA)

	eltsB := set.bits.AppendTo(nil)

	if a, b := fmt.Sprint(eltsA), fmt.Sprint(eltsB); a != b {
		t.Errorf("check(%s): hash=%s bits=%s (%s)", msg, a, b, &set.bits)
	}

	if err := set.bits.Check(); err != nil {
		t.Fatalf("Check(%s): %s: %#v", msg, err, &set.bits)
	}
}

// randomPset returns a parallel set of random size and elements.
func randomPset(prng *rand.Rand, maxSize int) *pset {
	set := makePset()
	size := int(prng.Int()) % maxSize
	for range size {
		// TODO(adonovan): benchmark how performance varies
		// with this sparsity parameter.
		n := int(prng.Int()) % 10000
		set.add(n)
	}
	return set
}

// TestRandomMutations performs the same random adds/removes on two
// set implementations and ensures that they compute the same result.
func TestRandomMutations(t *testing.T) {
	const debug = false

	set := makePset()
	prng := rand.New(rand.NewSource(0))
	for i := range 10000 {
		n := int(prng.Int())%2000 - 1000
		if i%2 == 0 {
			if debug {
				log.Printf("add %d", n)
			}
			set.add(n)
		} else {
			if debug {
				log.Printf("remove %d", n)
			}
			set.remove(n)
		}
		if debug {
			set.check(t, "post mutation")
		}
	}
	set.check(t, "final")
	if debug {
		log.Print(&set.bits)
	}
}

func TestLowerBound(t *testing.T) {
	// Use random sets of sizes from 0 to about 4000.
	prng := rand.New(rand.NewSource(0))
	for i := range uint(12) {
		x := randomPset(prng, 1<<i)
		for j := range 10000 {
			found := intsets.MaxInt
			for e := range x.hash {
				if e >= j && e < found {
					found = e
				}
			}
			if res := x.bits.LowerBound(j); res != found {
				t.Errorf("%s: LowerBound(%d)=%d, expected %d", &x.bits, j, res, found)
			}
		}
	}
}

// TestSetOperations exercises classic set operations: ∩ , ∪, \.
func TestSetOperations(t *testing.T) {
	prng := rand.New(rand.NewSource(0))

	// Use random sets of sizes from 0 to about 4000.
	// For each operator, we test variations such as
	// Z.op(X, Y), Z.op(X, Z) and Z.op(Z, Y) to exercise
	// the degenerate cases of each method implementation.
	for i := range uint(12) {
		X := randomPset(prng, 1<<i)
		Y := randomPset(prng, 1<<i)

		// TODO(adonovan): minimise dependencies between stanzas below.

		// Copy(X)
		C := makePset()
		C.bits.Copy(&Y.bits) // no effect on result
		C.bits.Copy(&X.bits)
		C.hash = X.hash
		C.check(t, "C.Copy(X)")
		C.bits.Copy(&C.bits)
		C.check(t, "C.Copy(C)")

		// U.Union(X, Y)
		U := makePset()
		U.bits.Union(&X.bits, &Y.bits)
		for n := range X.hash {
			U.hash[n] = true
		}
		for n := range Y.hash {
			U.hash[n] = true
		}
		U.check(t, "U.Union(X, Y)")

		// U.Union(X, X)
		U.bits.Union(&X.bits, &X.bits)
		U.hash = X.hash
		U.check(t, "U.Union(X, X)")

		// U.Union(U, Y)
		U = makePset()
		U.bits.Copy(&X.bits)
		U.bits.Union(&U.bits, &Y.bits)
		for n := range X.hash {
			U.hash[n] = true
		}
		for n := range Y.hash {
			U.hash[n] = true
		}
		U.check(t, "U.Union(U, Y)")

		// U.Union(X, U)
		U.bits.Copy(&Y.bits)
		U.bits.Union(&X.bits, &U.bits)
		U.check(t, "U.Union(X, U)")

		// U.UnionWith(U)
		U.bits.UnionWith(&U.bits)
		U.check(t, "U.UnionWith(U)")

		// I.Intersection(X, Y)
		I := makePset()
		I.bits.Intersection(&X.bits, &Y.bits)
		for n := range X.hash {
			if Y.hash[n] {
				I.hash[n] = true
			}
		}
		I.check(t, "I.Intersection(X, Y)")

		// I.Intersection(X, X)
		I.bits.Intersection(&X.bits, &X.bits)
		I.hash = X.hash
		I.check(t, "I.Intersection(X, X)")

		// I.Intersection(I, X)
		I.bits.Intersection(&I.bits, &X.bits)
		I.check(t, "I.Intersection(I, X)")

		// I.Intersection(X, I)
		I.bits.Intersection(&X.bits, &I.bits)
		I.check(t, "I.Intersection(X, I)")

		// I.Intersection(I, I)
		I.bits.Intersection(&I.bits, &I.bits)
		I.check(t, "I.Intersection(I, I)")

		// D.Difference(X, Y)
		D := makePset()
		D.bits.Difference(&X.bits, &Y.bits)
		for n := range X.hash {
			if !Y.hash[n] {
				D.hash[n] = true
			}
		}
		D.check(t, "D.Difference(X, Y)")

		// D.Difference(D, Y)
		D.bits.Copy(&X.bits)
		D.bits.Difference(&D.bits, &Y.bits)
		D.check(t, "D.Difference(D, Y)")

		// D.Difference(Y, D)
		D.bits.Copy(&X.bits)
		D.bits.Difference(&Y.bits, &D.bits)
		D.hash = make(map[int]bool)
		for n := range Y.hash {
			if !X.hash[n] {
				D.hash[n] = true
			}
		}
		D.check(t, "D.Difference(Y, D)")

		// D.Difference(X, X)
		D.bits.Difference(&X.bits, &X.bits)
		D.hash = nil
		D.check(t, "D.Difference(X, X)")

		// D.DifferenceWith(D)
		D.bits.Copy(&X.bits)
		D.bits.DifferenceWith(&D.bits)
		D.check(t, "D.DifferenceWith(D)")

		// SD.SymmetricDifference(X, Y)
		SD := makePset()
		SD.bits.SymmetricDifference(&X.bits, &Y.bits)
		for n := range X.hash {
			if !Y.hash[n] {
				SD.hash[n] = true
			}
		}
		for n := range Y.hash {
			if !X.hash[n] {
				SD.hash[n] = true
			}
		}
		SD.check(t, "SD.SymmetricDifference(X, Y)")

		// X.SymmetricDifferenceWith(Y)
		SD.bits.Copy(&X.bits)
		SD.bits.SymmetricDifferenceWith(&Y.bits)
		SD.check(t, "X.SymmetricDifference(Y)")

		// Y.SymmetricDifferenceWith(X)
		SD.bits.Copy(&Y.bits)
		SD.bits.SymmetricDifferenceWith(&X.bits)
		SD.check(t, "Y.SymmetricDifference(X)")

		// SD.SymmetricDifference(X, X)
		SD.bits.SymmetricDifference(&X.bits, &X.bits)
		SD.hash = nil
		SD.check(t, "SD.SymmetricDifference(X, X)")

		// SD.SymmetricDifference(X, Copy(X))
		X2 := makePset()
		X2.bits.Copy(&X.bits)
		SD.bits.SymmetricDifference(&X.bits, &X2.bits)
		SD.check(t, "SD.SymmetricDifference(X, Copy(X))")

		// Copy(X).SymmetricDifferenceWith(X)
		SD.bits.Copy(&X.bits)
		SD.bits.SymmetricDifferenceWith(&X.bits)
		SD.check(t, "Copy(X).SymmetricDifferenceWith(X)")
	}
}

// TestUnionWithChanged checks the 'changed' result of UnionWith.
func TestUnionWithChanged(t *testing.T) {
	setOf := func(elems ...int) *intsets.Sparse {
		s := new(intsets.Sparse)
		for _, elem := range elems {
			s.Insert(elem)
		}
		return s
	}

	checkUnionWith := func(x, y *intsets.Sparse) {
		xstr := x.String()
		prelen := x.Len()
		changed := x.UnionWith(y)
		if (x.Len() > prelen) != changed {
			t.Errorf("%s.UnionWith(%s) => %s, changed=%t", xstr, y, x, changed)
		}
	}

	// The case marked "!" is a regression test for Issue 50352,
	// which spuriously returned true when y ⊂ x.

	// same block
	checkUnionWith(setOf(1, 2), setOf(1, 2))
	checkUnionWith(setOf(1, 2, 3), setOf(1, 2)) // !
	checkUnionWith(setOf(1, 2), setOf(1, 2, 3))
	checkUnionWith(setOf(1, 2), setOf())

	// different blocks
	checkUnionWith(setOf(1, 1000000), setOf(1, 1000000))
	checkUnionWith(setOf(1, 2, 1000000), setOf(1, 2))
	checkUnionWith(setOf(1, 2), setOf(1, 2, 1000000))
	checkUnionWith(setOf(1, 1000000), setOf())
}

func TestIntersectionWith(t *testing.T) {
	// Edge cases: the pairs (1,1), (1000,2000), (8000,4000)
	// exercise the <, >, == cases in IntersectionWith that the
	// TestSetOperations data is too dense to cover.
	var X, Y intsets.Sparse
	X.Insert(1)
	X.Insert(1000)
	X.Insert(8000)
	Y.Insert(1)
	Y.Insert(2000)
	Y.Insert(4000)
	X.IntersectionWith(&Y)
	if got, want := X.String(), "{1}"; got != want {
		t.Errorf("IntersectionWith: got %s, want %s", got, want)
	}
}

func TestIntersects(t *testing.T) {
	prng := rand.New(rand.NewSource(0))

	for i := range uint(12) {
		X, Y := randomPset(prng, 1<<i), randomPset(prng, 1<<i)
		x, y := &X.bits, &Y.bits

		// test the slow way
		var z intsets.Sparse
		z.Copy(x)
		z.IntersectionWith(y)

		if got, want := x.Intersects(y), !z.IsEmpty(); got != want {
			t.Errorf("Intersects(%s, %s): got %v, want %v (%s)", x, y, got, want, &z)
		}

		// make it false
		a := x.AppendTo(nil)
		for _, v := range a {
			y.Remove(v)
		}

		if got, want := x.Intersects(y), false; got != want {
			t.Errorf("Intersects: got %v, want %v", got, want)
		}

		// make it true
		if x.IsEmpty() {
			continue
		}
		i := prng.Intn(len(a))
		y.Insert(a[i])

		if got, want := x.Intersects(y), true; got != want {
			t.Errorf("Intersects: got %v, want %v", got, want)
		}
	}
}

func TestSubsetOf(t *testing.T) {
	prng := rand.New(rand.NewSource(0))

	for i := range uint(12) {
		X, Y := randomPset(prng, 1<<i), randomPset(prng, 1<<i)
		x, y := &X.bits, &Y.bits

		// test the slow way
		var z intsets.Sparse
		z.Copy(x)
		z.DifferenceWith(y)

		if got, want := x.SubsetOf(y), z.IsEmpty(); got != want {
			t.Errorf("SubsetOf: got %v, want %v", got, want)
		}

		// make it true
		y.UnionWith(x)

		if got, want := x.SubsetOf(y), true; got != want {
			t.Errorf("SubsetOf: got %v, want %v", got, want)
		}

		// make it false
		if x.IsEmpty() {
			continue
		}
		a := x.AppendTo(nil)
		i := prng.Intn(len(a))
		y.Remove(a[i])

		if got, want := x.SubsetOf(y), false; got != want {
			t.Errorf("SubsetOf: got %v, want %v", got, want)
		}
	}
}

func TestBitString(t *testing.T) {
	for _, test := range []struct {
		input []int
		want  string
	}{
		{nil, "0"},
		{[]int{0}, "1"},
		{[]int{0, 4, 5}, "110001"},
		{[]int{0, 7, 177}, "1" + strings.Repeat("0", 169) + "10000001"},
		{[]int{-3, 0, 4, 5}, "110001.001"},
		{[]int{-3}, "0.001"},
	} {
		var set intsets.Sparse
		for _, x := range test.input {
			set.Insert(x)
		}
		if got := set.BitString(); got != test.want {
			t.Errorf("BitString(%s) = %s, want %s", set.String(), got, test.want)
		}
	}
}

func TestFailFastOnShallowCopy(t *testing.T) {
	var x intsets.Sparse
	x.Insert(1)

	y := x // shallow copy (breaks representation invariants)
	defer func() {
		got := fmt.Sprint(recover())
		want := "interface conversion: interface {} is nil, not intsets.to_copy_a_sparse_you_must_call_its_Copy_method"
		if got != want {
			t.Errorf("shallow copy: recover() = %q, want %q", got, want)
		}
	}()
	_ = y.String() // panics
	t.Error("didn't panic as expected")
}

// -- Benchmarks -------------------------------------------------------

// TODO(adonovan):
// - Add benchmarks of each method.
// - Gather set distributions from pointer analysis.
// - Measure memory usage.

func benchmarkInsertProbeSparse(b *testing.B, size, spread int) {
	prng := rand.New(rand.NewSource(0))
	// Generate our insertions and probes beforehand (we don't want to benchmark
	// the prng).
	insert := make([]int, size)
	probe := make([]int, size*2)
	for i := range insert {
		insert[i] = prng.Int() % spread
	}
	for i := range probe {
		probe[i] = prng.Int() % spread
	}

	var x intsets.Sparse
	for b.Loop() {
		x.Clear()
		for _, n := range insert {
			x.Insert(n)
		}
		hits := 0
		for _, n := range probe {
			if x.Has(n) {
				hits++
			}
		}
		// Use the variable so it doesn't get optimized away.
		if hits > len(probe) {
			b.Fatalf("%d hits, only %d probes", hits, len(probe))
		}
	}
}

func BenchmarkInsertProbeSparse_2_10(b *testing.B) {
	benchmarkInsertProbeSparse(b, 2, 10)
}

func BenchmarkInsertProbeSparse_10_10(b *testing.B) {
	benchmarkInsertProbeSparse(b, 10, 10)
}

func BenchmarkInsertProbeSparse_10_1000(b *testing.B) {
	benchmarkInsertProbeSparse(b, 10, 1000)
}

func BenchmarkInsertProbeSparse_100_100(b *testing.B) {
	benchmarkInsertProbeSparse(b, 100, 100)
}

func BenchmarkInsertProbeSparse_100_10000(b *testing.B) {
	benchmarkInsertProbeSparse(b, 100, 1000)
}

func BenchmarkUnionDifferenceSparse(b *testing.B) {
	prng := rand.New(rand.NewSource(0))
	for b.Loop() {
		var x, y, z intsets.Sparse
		for i := range 1000 {
			n := int(prng.Int()) % 100000
			if i%2 == 0 {
				x.Insert(n)
			} else {
				y.Insert(n)
			}
		}
		z.Union(&x, &y)
		z.Difference(&x, &y)
	}
}

func BenchmarkUnionDifferenceHashTable(b *testing.B) {
	prng := rand.New(rand.NewSource(0))
	for b.Loop() {
		x, y, z := make(map[int]bool), make(map[int]bool), make(map[int]bool)
		for i := range 1000 {
			n := int(prng.Int()) % 100000
			if i%2 == 0 {
				x[n] = true
			} else {
				y[n] = true
			}
		}
		// union
		for n := range x {
			z[n] = true
		}
		for n := range y {
			z[n] = true
		}
		// difference
		z = make(map[int]bool)
		for n := range y {
			if !x[n] {
				z[n] = true
			}
		}
	}
}

func BenchmarkAppendTo(b *testing.B) {
	prng := rand.New(rand.NewSource(0))
	var x intsets.Sparse
	for range 1000 {
		x.Insert(int(prng.Int()) % 10000)
	}
	var space [1000]int
	for b.Loop() {
		x.AppendTo(space[:0])
	}
}


================================================
FILE: copyright/copyright.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package copyright checks that files have the correct copyright notices.
package copyright

import (
	"go/ast"
	"go/parser"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

// (used only by tests)
func checkCopyright(dir string) ([]string, error) {
	var files []string
	err := filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			// Skip directories like ".git".
			if strings.HasPrefix(d.Name(), ".") && d.Name() != "." && d.Name() != ".." {
				return filepath.SkipDir
			}
			// Skip any directory that starts with an underscore, as the go
			// command would.
			if strings.HasPrefix(d.Name(), "_") {
				return filepath.SkipDir
			}
			return nil
		}
		needsCopyright, err := checkFile(dir, path)
		if err != nil {
			return err
		}
		if needsCopyright {
			files = append(files, path)
		}
		return nil
	})
	return files, err
}

var copyrightRe = regexp.MustCompile(`Copyright \d{4} The Go Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file.`)

func checkFile(toolsDir, filename string) (bool, error) {
	// Only check Go files.
	if !strings.HasSuffix(filename, ".go") {
		return false, nil
	}
	// Don't check testdata files.
	normalized := strings.TrimPrefix(filepath.ToSlash(filename), filepath.ToSlash(toolsDir))
	if strings.Contains(normalized, "/testdata/") {
		return false, nil
	}
	// goyacc is the only file with a different copyright header.
	if strings.HasSuffix(normalized, "cmd/goyacc/yacc.go") {
		return false, nil
	}
	content, err := os.ReadFile(filename)
	if err != nil {
		return false, err
	}
	fset := token.NewFileSet()
	parsed, err := parser.ParseFile(fset, filename, content, parser.ParseComments)
	if err != nil {
		return false, err
	}
	// Don't require headers on generated files.
	if ast.IsGenerated(parsed) {
		return false, nil
	}
	shouldAddCopyright := true
	for _, c := range parsed.Comments {
		// The copyright should appear before the package declaration.
		if c.Pos() > parsed.Package {
			break
		}
		if copyrightRe.MatchString(c.Text()) {
			shouldAddCopyright = false
			break
		}
	}
	return shouldAddCopyright, nil
}


================================================
FILE: copyright/copyright_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package copyright

import (
	"strings"
	"testing"
)

func TestToolsCopyright(t *testing.T) {
	files, err := checkCopyright("..")
	if err != nil {
		t.Fatal(err)
	}
	if len(files) > 0 {
		t.Errorf("The following files are missing copyright notices:\n%s", strings.Join(files, "\n"))
	}
}


================================================
FILE: cover/profile.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cover provides support for parsing coverage profiles
// generated by "go test -coverprofile=cover.out".
package cover // import "golang.org/x/tools/cover"

import (
	"bufio"
	"errors"
	"fmt"
	"io"
	"math"
	"os"
	"sort"
	"strconv"
	"strings"
)

// Profile represents the profiling data for a specific file.
type Profile struct {
	FileName string
	Mode     string
	Blocks   []ProfileBlock
}

// ProfileBlock represents a single block of profiling data.
type ProfileBlock struct {
	StartLine, StartCol int
	EndLine, EndCol     int
	NumStmt, Count      int
}

type byFileName []*Profile

func (p byFileName) Len() int           { return len(p) }
func (p byFileName) Less(i, j int) bool { return p[i].FileName < p[j].FileName }
func (p byFileName) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

// ParseProfiles parses profile data in the specified file and returns a
// Profile for each source file described therein.
func ParseProfiles(fileName string) ([]*Profile, error) {
	pf, err := os.Open(fileName)
	if err != nil {
		return nil, err
	}
	defer pf.Close()
	return ParseProfilesFromReader(pf)
}

// ParseProfilesFromReader parses profile data from the Reader and
// returns a Profile for each source file described therein.
func ParseProfilesFromReader(rd io.Reader) ([]*Profile, error) {
	// First line is "mode: foo", where foo is "set", "count", or "atomic".
	// Rest of file is in the format
	//	encoding/base64/base64.go:34.44,37.40 3 1
	// where the fields are: name.go:line.column,line.column numberOfStatements count
	files := make(map[string]*Profile)
	s := bufio.NewScanner(rd)
	mode := ""
	for s.Scan() {
		line := s.Text()
		if mode == "" {
			const p = "mode: "
			if !strings.HasPrefix(line, p) || line == p {
				return nil, fmt.Errorf("bad mode line: %v", line)
			}
			mode = line[len(p):]
			continue
		}
		fn, b, err := parseLine(line)
		if err != nil {
			return nil, fmt.Errorf("line %q doesn't match expected format: %v", line, err)
		}
		p := files[fn]
		if p == nil {
			p = &Profile{
				FileName: fn,
				Mode:     mode,
			}
			files[fn] = p
		}
		p.Blocks = append(p.Blocks, b)
	}
	if err := s.Err(); err != nil {
		return nil, err
	}
	for _, p := range files {
		sort.Sort(blocksByStart(p.Blocks))
		// Merge samples from the same location.
		j := 1
		for i := 1; i < len(p.Blocks); i++ {
			b := p.Blocks[i]
			last := p.Blocks[j-1]
			if b.StartLine == last.StartLine &&
				b.StartCol == last.StartCol &&
				b.EndLine == last.EndLine &&
				b.EndCol == last.EndCol {
				if b.NumStmt != last.NumStmt {
					return nil, fmt.Errorf("inconsistent NumStmt: changed from %d to %d", last.NumStmt, b.NumStmt)
				}
				if mode == "set" {
					p.Blocks[j-1].Count |= b.Count
				} else {
					p.Blocks[j-1].Count += b.Count
				}
				continue
			}
			p.Blocks[j] = b
			j++
		}
		p.Blocks = p.Blocks[:j]
	}
	// Generate a sorted slice.
	profiles := make([]*Profile, 0, len(files))
	for _, profile := range files {
		profiles = append(profiles, profile)
	}
	sort.Sort(byFileName(profiles))
	return profiles, nil
}

// parseLine parses a line from a coverage file.
// It is equivalent to the regex
// ^(.+):([0-9]+)\.([0-9]+),([0-9]+)\.([0-9]+) ([0-9]+) ([0-9]+)$
//
// However, it is much faster: https://golang.org/cl/179377
func parseLine(l string) (fileName string, block ProfileBlock, err error) {
	end := len(l)

	b := ProfileBlock{}
	b.Count, end, err = seekBack(l, ' ', end, "Count")
	if err != nil {
		return "", b, err
	}
	b.NumStmt, end, err = seekBack(l, ' ', end, "NumStmt")
	if err != nil {
		return "", b, err
	}
	b.EndCol, end, err = seekBack(l, '.', end, "EndCol")
	if err != nil {
		return "", b, err
	}
	b.EndLine, end, err = seekBack(l, ',', end, "EndLine")
	if err != nil {
		return "", b, err
	}
	b.StartCol, end, err = seekBack(l, '.', end, "StartCol")
	if err != nil {
		return "", b, err
	}
	b.StartLine, end, err = seekBack(l, ':', end, "StartLine")
	if err != nil {
		return "", b, err
	}
	fn := l[0:end]
	if fn == "" {
		return "", b, errors.New("a FileName cannot be blank")
	}
	return fn, b, nil
}

// seekBack searches backwards from end to find sep in l, then returns the
// value between sep and end as an integer.
// If seekBack fails, the returned error will reference what.
func seekBack(l string, sep byte, end int, what string) (value int, nextSep int, err error) {
	// Since we're seeking backwards and we know only ASCII is legal for these values,
	// we can ignore the possibility of non-ASCII characters.
	for start := end - 1; start >= 0; start-- {
		if l[start] == sep {
			i, err := strconv.Atoi(l[start+1 : end])
			if err != nil {
				return 0, 0, fmt.Errorf("couldn't parse %q: %v", what, err)
			}
			if i < 0 {
				return 0, 0, fmt.Errorf("negative values are not allowed for %s, found %d", what, i)
			}
			return i, start, nil
		}
	}
	return 0, 0, fmt.Errorf("couldn't find a %s before %s", string(sep), what)
}

type blocksByStart []ProfileBlock

func (b blocksByStart) Len() int      { return len(b) }
func (b blocksByStart) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b blocksByStart) Less(i, j int) bool {
	bi, bj := b[i], b[j]
	return bi.StartLine < bj.StartLine || bi.StartLine == bj.StartLine && bi.StartCol < bj.StartCol
}

// Boundary represents the position in a source file of the beginning or end of a
// block as reported by the coverage profile. In HTML mode, it will correspond to
// the opening or closing of a <span> tag and will be used to colorize the source
type Boundary struct {
	Offset int     // Location as a byte offset in the source file.
	Start  bool    // Is this the start of a block?
	Count  int     // Event count from the cover profile.
	Norm   float64 // Count normalized to [0..1].
	Index  int     // Order in input file.
}

// Boundaries returns a Profile as a set of Boundary objects within the provided src.
func (p *Profile) Boundaries(src []byte) (boundaries []Boundary) {
	// Find maximum count.
	max := 0
	for _, b := range p.Blocks {
		if b.Count > max {
			max = b.Count
		}
	}
	// Divisor for normalization.
	divisor := math.Log(float64(max))

	// boundary returns a Boundary, populating the Norm field with a normalized Count.
	index := 0
	boundary := func(offset int, start bool, count int) Boundary {
		b := Boundary{Offset: offset, Start: start, Count: count, Index: index}
		index++
		if !start || count == 0 {
			return b
		}
		if max <= 1 {
			b.Norm = 0.8 // Profile is in"set" mode; we want a heat map. Use cov8 in the CSS.
		} else if count > 0 {
			b.Norm = math.Log(float64(count)) / divisor
		}
		return b
	}

	line, col := 1, 2 // TODO: Why is this 2?
	for si, bi := 0, 0; si < len(src) && bi < len(p.Blocks); {
		b := p.Blocks[bi]
		if b.StartLine == line && b.StartCol == col {
			boundaries = append(boundaries, boundary(si, true, b.Count))
		}
		if b.EndLine == line && b.EndCol == col || line > b.EndLine {
			boundaries = append(boundaries, boundary(si, false, 0))
			bi++
			continue // Don't advance through src; maybe the next block starts here.
		}
		if src[si] == '\n' {
			line++
			col = 0
		}
		col++
		si++
	}
	sort.Sort(boundariesByPos(boundaries))
	return
}

type boundariesByPos []Boundary

func (b boundariesByPos) Len() int      { return len(b) }
func (b boundariesByPos) Swap(i, j int) { b[i], b[j] = b[j], b[i] }
func (b boundariesByPos) Less(i, j int) bool {
	if b[i].Offset == b[j].Offset {
		// Boundaries at the same offset should be ordered according to
		// their original position.
		return b[i].Index < b[j].Index
	}
	return b[i].Offset < b[j].Offset
}


================================================
FILE: cover/profile_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cover

import (
	"fmt"
	"os"
	"path/filepath"
	"reflect"
	"testing"
)

func TestParseProfiles(t *testing.T) {
	tests := []struct {
		name      string
		input     string
		output    []*Profile
		expectErr bool
	}{
		{
			name:   "parsing an empty file produces empty output",
			input:  `mode: set`,
			output: []*Profile{},
		},
		{
			name: "simple valid file produces expected output",
			input: `mode: set
some/fancy/path:42.69,44.16 2 1`,
			output: []*Profile{
				{
					FileName: "some/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 1,
						},
					},
				},
			},
		},
		{
			name: "file with syntax characters in path produces expected output",
			input: `mode: set
some fancy:path/some,file.go:42.69,44.16 2 1`,
			output: []*Profile{
				{
					FileName: "some fancy:path/some,file.go",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 1,
						},
					},
				},
			},
		},
		{
			name: "file with multiple blocks in one file produces expected output",
			input: `mode: set
some/fancy/path:42.69,44.16 2 1
some/fancy/path:44.16,46.3 1 0`,
			output: []*Profile{
				{
					FileName: "some/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 1,
						},
						{
							StartLine: 44, StartCol: 16,
							EndLine: 46, EndCol: 3,
							NumStmt: 1, Count: 0,
						},
					},
				},
			},
		},
		{
			name: "file with multiple files produces expected output",
			input: `mode: set
another/fancy/path:44.16,46.3 1 0
some/fancy/path:42.69,44.16 2 1`,
			output: []*Profile{
				{
					FileName: "another/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 44, StartCol: 16,
							EndLine: 46, EndCol: 3,
							NumStmt: 1, Count: 0,
						},
					},
				},
				{
					FileName: "some/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 1,
						},
					},
				},
			},
		},
		{
			name: "intertwined files are merged correctly",
			input: `mode: set
some/fancy/path:42.69,44.16 2 1
another/fancy/path:47.2,47.13 1 1
some/fancy/path:44.16,46.3 1 0`,
			output: []*Profile{
				{
					FileName: "another/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 47, StartCol: 2,
							EndLine: 47, EndCol: 13,
							NumStmt: 1, Count: 1,
						},
					},
				},
				{
					FileName: "some/fancy/path",
					Mode:     "set",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 1,
						},
						{
							StartLine: 44, StartCol: 16,
							EndLine: 46, EndCol: 3,
							NumStmt: 1, Count: 0,
						},
					},
				},
			},
		},
		{
			name: "duplicate blocks are merged correctly",
			input: `mode: count
some/fancy/path:42.69,44.16 2 4
some/fancy/path:42.69,44.16 2 3`,
			output: []*Profile{
				{
					FileName: "some/fancy/path",
					Mode:     "count",
					Blocks: []ProfileBlock{
						{
							StartLine: 42, StartCol: 69,
							EndLine: 44, EndCol: 16,
							NumStmt: 2, Count: 7,
						},
					},
				},
			},
		},
		{
			name:      "an invalid mode line is an error",
			input:     `mode:count`,
			expectErr: true,
		},
		{
			name: "a missing field is an error",
			input: `mode: count
some/fancy/path:42.69,44.16 2`,
			expectErr: true,
		},
		{
			name: "a missing path field is an error",
			input: `mode: count
42.69,44.16 2 3`,
			expectErr: true,
		},
		{
			name: "a non-numeric count is an error",
			input: `mode: count
42.69,44.16 2 nope`,
			expectErr: true,
		},
		{
			name: "an empty path is an error",
			input: `mode: count
:42.69,44.16 2 3`,
			expectErr: true,
		},
		{
			name: "a negative count is an error",
			input: `mode: count
some/fancy/path:42.69,44.16 2 -1`,
			expectErr: true,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			fname := filepath.Join(t.TempDir(), "test.cov")
			if err := os.WriteFile(fname, []byte(tc.input), 0644); err != nil {
				t.Fatal(err)
			}

			result, err := ParseProfiles(fname)
			if err != nil {
				if !tc.expectErr {
					t.Errorf("Unexpected error: %v", err)
				}
				return
			}
			if tc.expectErr {
				t.Errorf("Expected an error, but got value %q", stringifyProfileArray(result))
			}
			if !reflect.DeepEqual(result, tc.output) {
				t.Errorf("Mismatched results.\nExpected: %s\nActual:   %s", stringifyProfileArray(tc.output), stringifyProfileArray(result))
			}
		})
	}
}

func stringifyProfileArray(profiles []*Profile) string {
	deref := make([]Profile, 0, len(profiles))
	for _, p := range profiles {
		deref = append(deref, *p)
	}
	return fmt.Sprintf("%#v", deref)
}

func BenchmarkParseLine(b *testing.B) {
	const line = "k8s.io/kubernetes/cmd/kube-controller-manager/app/options/ttlafterfinishedcontroller.go:31.73,32.14 1 1"
	b.SetBytes(int64(len(line)))
	for b.Loop() {
		parseLine(line)
	}
}


================================================
FILE: go/analysis/analysis.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysis

import (
	"flag"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"reflect"
	"time"
)

// An Analyzer describes an analysis function and its options.
type Analyzer struct {
	// The Name of the analyzer must be a valid Go identifier
	// as it may appear in command-line flags, URLs, and so on.
	Name string

	// Doc is the documentation for the analyzer.
	// The part before the first "\n\n" is the title
	// (no capital or period, max ~60 letters).
	Doc string

	// URL holds an optional link to a web page with additional
	// documentation for this analyzer.
	URL string

	// Flags defines any flags accepted by the analyzer.
	// The manner in which these flags are exposed to the user
	// depends on the driver which runs the analyzer.
	Flags flag.FlagSet

	// Run applies the analyzer to a package.
	// It returns an error if the analyzer failed.
	//
	// On success, the Run function may return a result
	// computed by the Analyzer; its type must match ResultType.
	// The driver makes this result available as an input to
	// another Analyzer that depends directly on this one (see
	// Requires) when it analyzes the same package.
	//
	// To pass analysis results between packages (and thus
	// potentially between address spaces), use Facts, which are
	// serializable.
	Run func(*Pass) (any, error)

	// RunDespiteErrors allows the driver to invoke
	// the Run method of this analyzer even on a
	// package that contains parse or type errors.
	// The [Pass.TypeErrors] field may consequently be non-empty.
	RunDespiteErrors bool

	// Requires is a set of analyzers that must run successfully
	// before this one on a given package. This analyzer may inspect
	// the outputs produced by each analyzer in Requires.
	// The graph over analyzers implied by Requires edges must be acyclic.
	//
	// Requires establishes a "horizontal" dependency between
	// analysis passes (different analyzers, same package).
	Requires []*Analyzer

	// ResultType is the type of the optional result of the Run function.
	ResultType reflect.Type

	// FactTypes indicates that this analyzer imports and exports
	// Facts of the specified concrete types.
	// An analyzer that uses facts may assume that its import
	// dependencies have been similarly analyzed before it runs.
	// Facts must be pointers.
	//
	// FactTypes establishes a "vertical" dependency between
	// analysis passes (same analyzer, different packages).
	FactTypes []Fact
}

func (a *Analyzer) String() string { return a.Name }

// A Pass provides information to the Run function that
// applies a specific analyzer to a single Go package.
//
// It forms the interface between the analysis logic and the driver
// program, and has both input and an output components.
//
// As in a compiler, one pass may depend on the result computed by another.
//
// The Run function should not call any of the Pass functions concurrently.
type Pass struct {
	Analyzer *Analyzer // the identity of the current analyzer

	// syntax and type information
	Fset         *token.FileSet // file position information; Run may add new files
	Files        []*ast.File    // the abstract syntax tree of each file
	OtherFiles   []string       // names of non-Go files of this package
	IgnoredFiles []string       // names of ignored source files in this package
	Pkg          *types.Package // type information about the package
	TypesInfo    *types.Info    // type information about the syntax trees
	TypesSizes   types.Sizes    // function for computing sizes of types
	TypeErrors   []types.Error  // type errors (only if Analyzer.RunDespiteErrors)

	Module *Module // the package's enclosing module (possibly nil in some drivers)

	// Report reports a Diagnostic, a finding about a specific location
	// in the analyzed source code such as a potential mistake.
	// It may be called by the Run function.
	Report func(Diagnostic)

	// ResultOf provides the inputs to this analysis pass, which are
	// the corresponding results of its prerequisite analyzers.
	// The map keys are the elements of Analysis.Required,
	// and the type of each corresponding value is the required
	// analysis's ResultType.
	ResultOf map[*Analyzer]any

	// ReadFile returns the contents of the named file.
	//
	// The only valid file names are the elements of OtherFiles
	// and IgnoredFiles, and names returned by
	// Fset.File(f.FileStart).Name() for each f in Files.
	//
	// Analyzers must use this function (if provided) instead of
	// accessing the file system directly. This allows a driver to
	// provide a virtualized file tree (including, for example,
	// unsaved editor buffers) and to track dependencies precisely
	// to avoid unnecessary recomputation.
	ReadFile func(filename string) ([]byte, error)

	// -- facts --

	// ImportObjectFact retrieves a fact associated with obj.
	// Given a value ptr of type *T, where *T satisfies Fact,
	// ImportObjectFact copies the value to *ptr.
	//
	// ImportObjectFact panics if called after the pass is complete.
	// ImportObjectFact is not concurrency-safe.
	ImportObjectFact func(obj types.Object, fact Fact) bool

	// ImportPackageFact retrieves a fact associated with package pkg,
	// which must be this package or one of its dependencies.
	// See comments for ImportObjectFact.
	ImportPackageFact func(pkg *types.Package, fact Fact) bool

	// ExportObjectFact associates a fact of type *T with the obj,
	// replacing any previous fact of that type.
	//
	// ExportObjectFact panics if it is called after the pass is
	// complete, or if obj does not belong to the package being analyzed.
	// ExportObjectFact is not concurrency-safe.
	ExportObjectFact func(obj types.Object, fact Fact)

	// ExportPackageFact associates a fact with the current package.
	// See comments for ExportObjectFact.
	ExportPackageFact func(fact Fact)

	// AllPackageFacts returns a new slice containing all package
	// facts of the analysis's FactTypes in unspecified order.
	// See comments for AllObjectFacts.
	AllPackageFacts func() []PackageFact

	// AllObjectFacts returns a new slice containing all object
	// facts of the analysis's FactTypes in unspecified order.
	//
	// The result includes all facts exported by packages
	// whose symbols are referenced by the current package
	// (by qualified identifiers or field/method selections).
	// And it includes all facts exported from the current
	// package by the current analysis pass.
	AllObjectFacts func() []ObjectFact

	/* Further fields may be added in future. */
}

// PackageFact is a package together with an associated fact.
type PackageFact struct {
	Package *types.Package
	Fact    Fact
}

// ObjectFact is an object together with an associated fact.
type ObjectFact struct {
	Object types.Object
	Fact   Fact
}

// Reportf is a helper function that reports a Diagnostic using the
// specified position and formatted error message.
func (pass *Pass) Reportf(pos token.Pos, format string, args ...any) {
	msg := fmt.Sprintf(format, args...)
	pass.Report(Diagnostic{Pos: pos, Message: msg})
}

// The Range interface provides a range. It's equivalent to and satisfied by
// ast.Node.
type Range interface {
	Pos() token.Pos // position of first character belonging to the node
	End() token.Pos // position of first character immediately after the node
}

// ReportRangef is a helper function that reports a Diagnostic using the
// range provided. ast.Node values can be passed in as the range because
// they satisfy the Range interface.
func (pass *Pass) ReportRangef(rng Range, format string, args ...any) {
	msg := fmt.Sprintf(format, args...)
	pass.Report(Diagnostic{Pos: rng.Pos(), End: rng.End(), Message: msg})
}

func (pass *Pass) String() string {
	return fmt.Sprintf("%s@%s", pass.Analyzer.Name, pass.Pkg.Path())
}

// A Fact is an intermediate fact produced during analysis.
//
// Each fact is associated with a named declaration (a types.Object) or
// with a package as a whole. A single object or package may have
// multiple associated facts, but only one of any particular fact type.
//
// A Fact represents a predicate such as "never returns", but does not
// represent the subject of the predicate such as "function F" or "package P".
//
// Facts may be produced in one analysis pass and consumed by another
// analysis pass even if these are in different address spaces.
// If package P imports Q, all facts about Q produced during
// analysis of that package will be available during later analysis of P.
// Facts are analogous to type export data in a build system:
// just as export data enables separate compilation of several passes,
// facts enable "separate analysis".
//
// Each pass (a, p) starts with the set of facts produced by the
// same analyzer a applied to the packages directly imported by p.
// The analysis may add facts to the set, and they may be exported in turn.
// An analysis's Run function may retrieve facts by calling
// Pass.Import{Object,Package}Fact and update them using
// Pass.Export{Object,Package}Fact.
//
// A fact is logically private to its Analysis. To pass values
// between different analyzers, use the results mechanism;
// see Analyzer.Requires, Analyzer.ResultType, and Pass.ResultOf.
//
// A Fact type must be a pointer.
// Facts are encoded and decoded using encoding/gob.
// A Fact may implement the GobEncoder/GobDecoder interfaces
// to customize its encoding. Fact encoding should not fail.
//
// A Fact should not be modified once exported.
type Fact interface {
	AFact() // dummy method to avoid type errors
}

// A Module describes the module to which a package belongs.
type Module struct {
	Path      string       // module path
	Version   string       // module version ("" if unknown, such as for workspace modules)
	Replace   *Module      // replaced by this module
	Time      *time.Time   // time version was created
	Main      bool         // is this the main module?
	Indirect  bool         // is this module only an indirect dependency of main module?
	Dir       string       // directory holding files for this module, if any
	GoMod     string       // path to go.mod file used when loading this module, if any
	GoVersion string       // go version used in module (e.g. "go1.22.0")
	Error     *ModuleError // error loading module
}

// ModuleError holds errors loading a module.
type ModuleError struct {
	Err string // the error itself
}


================================================
FILE: go/analysis/analysistest/analysistest.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package analysistest provides utilities for testing analyzers.
package analysistest

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"log"
	"maps"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"slices"
	"sort"
	"strconv"
	"strings"
	"testing"
	"text/scanner"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/checker"
	"golang.org/x/tools/go/analysis/internal"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/analysis/driverutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

// WriteFiles is a helper function that creates a temporary directory
// and populates it with a GOPATH-style project using filemap (which
// maps file names to contents). On success it returns the name of the
// directory and a cleanup function to delete it.
//
// TODO(adonovan): provide a newer version that accepts a testing.T,
// calls T.TempDir, and calls T.Fatal on any error, avoiding the need
// to return cleanup or err:
//
//	func WriteFilesToTmp(t *testing.T filemap map[string]string) string
func WriteFiles(filemap map[string]string) (dir string, cleanup func(), err error) {
	gopath, err := os.MkdirTemp("", "analysistest")
	if err != nil {
		return "", nil, err
	}
	cleanup = func() { os.RemoveAll(gopath) }

	for name, content := range filemap {
		filename := filepath.Join(gopath, "src", name)
		os.MkdirAll(filepath.Dir(filename), 0777) // ignore error
		if err := os.WriteFile(filename, []byte(content), 0666); err != nil {
			cleanup()
			return "", nil, err
		}
	}
	return gopath, cleanup, nil
}

// TestData returns the effective filename of
// the program's "testdata" directory.
// This function may be overridden by projects using
// an alternative build system (such as Blaze) that
// does not run a test in its package directory.
var TestData = func() string {
	testdata, err := filepath.Abs("testdata")
	if err != nil {
		log.Fatal(err)
	}
	return testdata
}

// Testing is an abstraction of a *testing.T.
type Testing interface {
	Errorf(format string, args ...any)
}

// RunWithSuggestedFixes behaves like Run, but additionally applies
// suggested fixes and verifies their output.
//
// It uses golden files, placed alongside each source file, to express
// the desired output: the expected transformation of file example.go
// is specified in file example.go.golden.
//
// Golden files may be of two forms: a plain Go source file, or a
// txtar archive.
//
// A plain Go source file indicates the expected result of applying
// all suggested fixes to the original file.
//
// A txtar archive specifies, in each section, the expected result of
// applying all suggested fixes of a given message to the original
// file; the name of the archive section is the fix's message. In this
// way, the various alternative fixes offered by a single diagnostic
// can be tested independently. Here's an example:
//
//	-- turn into single negation --
//	package pkg
//
//	func fn(b1, b2 bool) {
//		if !b1 { // want `negating a boolean twice`
//			println()
//		}
//	}
//
//	-- remove double negation --
//	package pkg
//
//	func fn(b1, b2 bool) {
//		if b1 { // want `negating a boolean twice`
//			println()
//		}
//	}
//
// # Conflicts
//
// Regardless of the form of the golden file, it is possible for
// multiple fixes to conflict, either because they overlap, or are
// close enough together that the particular diff algorithm cannot
// separate them.
//
// RunWithSuggestedFixes uses a simple three-way merge to accumulate
// fixes, similar to a git merge. The merge algorithm may be able to
// coalesce identical edits, for example duplicate imports of the same
// package. (Bear in mind that this is an editorial decision. In
// general, coalescing identical edits may not be correct: consider
// two statements that increment the same counter.)
//
// If there are conflicts, the test fails. In any case, the
// non-conflicting edits will be compared against the expected output.
// In this situation, we recommend that you increase the textual
// separation between conflicting parts or, if that fails, split
// your tests into smaller parts.
//
// If a diagnostic offers multiple fixes for the same problem, they
// are almost certain to conflict, so in this case you should define
// the expected output using a multi-section txtar file as described
// above.
func RunWithSuggestedFixes(t Testing, dir string, a *analysis.Analyzer, patterns ...string) []*Result {
	results := Run(t, dir, a, patterns...)

	// If the immediate caller of RunWithSuggestedFixes is in
	// x/tools, we apply stricter checks as required by gopls.
	inTools := false
	{
		var pcs [1]uintptr
		n := runtime.Callers(1, pcs[:])
		frames := runtime.CallersFrames(pcs[:n])
		fr, _ := frames.Next()
		if fr.Func != nil && strings.HasPrefix(fr.Func.Name(), "golang.org/x/tools/") {
			inTools = true
		}
	}

	generated := make(map[*token.File]bool)

	// Process each result (package) separately, matching up the suggested
	// fixes into a diff, which we will compare to the .golden file.  We have
	// to do this per-result in case a file appears in two packages, such as in
	// packages with tests, where mypkg/a.go will appear in both mypkg and
	// mypkg.test.  In that case, the analyzer may suggest the same set of
	// changes to a.go for each package.  If we merge all the results, those
	// changes get doubly applied, which will cause conflicts or mismatches.
	// Validating the results separately means as long as the two analyses
	// don't produce conflicting suggestions for a single file, everything
	// should match up.
	for _, result := range results {
		act := result.Action

		// Compute set of generated files.
		for _, file := range internal.ActionPass(act).Files {
			// Memoize, since there may be many actions
			// for the same package (list of files).
			tokFile := act.Package.Fset.File(file.Pos())
			if _, seen := generated[tokFile]; !seen {
				generated[tokFile] = ast.IsGenerated(file)
			}
		}

		// For each fix, split its edits by file and convert to diff form.
		var (
			// fixEdits: message -> fixes -> filename -> edits
			//
			// TODO(adonovan): this mapping assumes fix.Messages
			// are unique across analyzers, whereas they are only
			// unique within a given Diagnostic.
			fixEdits     = make(map[string][]map[string][]diff.Edit)
			allFilenames = make(map[string]bool)
		)
		for _, diag := range act.Diagnostics {
			// Fixes are validated upon creation in Pass.Report.
		fixloop:
			for _, fix := range diag.SuggestedFixes {
				// Assert that lazy fixes have a Category (#65578, #65087).
				if inTools && len(fix.TextEdits) == 0 && diag.Category == "" {
					t.Errorf("missing Diagnostic.Category for SuggestedFix without TextEdits (gopls requires the category for the name of the fix command")
				}

				// Skip any fix that edits a generated file.
				for _, edit := range fix.TextEdits {
					file := act.Package.Fset.File(edit.Pos)
					if generated[file] {
						continue fixloop
					}
				}

				// Convert edits to diff form.
				// Group fixes by message and file.
				edits := make(map[string][]diff.Edit)
				for _, edit := range fix.TextEdits {
					file := act.Package.Fset.File(edit.Pos)
					allFilenames[file.Name()] = true
					edits[file.Name()] = append(edits[file.Name()], diff.Edit{
						Start: file.Offset(edit.Pos),
						End:   file.Offset(edit.End),
						New:   string(edit.NewText),
					})
				}
				fixEdits[fix.Message] = append(fixEdits[fix.Message], edits)
			}
		}

		merge := func(file, message string, x, y []diff.Edit) []diff.Edit {
			z, ok := diff.Merge(x, y)
			if !ok {
				t.Errorf("in file %s, conflict applying fix %q", file, message)
				return x // discard y
			}
			return z
		}

		// Because the checking is driven by original
		// filenames, there is no way to express that a fix
		// (e.g. extract declaration) creates a new file.
		for _, filename := range slices.Sorted(maps.Keys(allFilenames)) {
			// Read the original file.
			content, err := os.ReadFile(filename)
			if err != nil {
				t.Errorf("error reading %s: %v", filename, err)
				continue
			}

			// check checks that the accumulated edits applied
			// to the original content yield the wanted content.
			check := func(prefix string, accumulated []diff.Edit, want []byte) {
				if err := applyDiffsAndCompare(result.Pass.Pkg, filename, content, want, accumulated); err != nil {
					t.Errorf("%s: %s", prefix, err)
				}
			}

			// Read the golden file. It may have one of two forms:
			// (1) A txtar archive with one section per fix title,
			//     including all fixes of just that title.
			// (2) The expected output for file.Name after all (?) fixes are applied.
			//     This form requires that no diagnostic has multiple fixes.
			ar, err := txtar.ParseFile(filename + ".golden")
			if err != nil {
				t.Errorf("error reading %s.golden: %v", filename, err)
				continue
			}
			if len(ar.Files) > 0 {
				// Form #1: one archive section per kind of suggested fix.
				if len(ar.Comment) > 0 {
					// Disallow the combination of comment and archive sections.
					t.Errorf("%s.golden has leading comment; we don't know what to do with it", filename)
					continue
				}

				// Each archive section is named for a fix.Message.
				// Accumulate the parts of the fix that apply to the current file,
				// using a simple three-way merge, discarding conflicts,
				// then apply the merged edits and compare to the archive section.
				for _, section := range ar.Files {
					message, want := section.Name, section.Data
					var accumulated []diff.Edit
					for _, fix := range fixEdits[message] {
						accumulated = merge(filename, message, accumulated, fix[filename])
					}
					check(fmt.Sprintf("all fixes of message %q", message), accumulated, want)
				}

			} else {
				// Form #2: all suggested fixes are represented by a single file.
				want := ar.Comment
				var accumulated []diff.Edit
				for _, message := range slices.Sorted(maps.Keys(fixEdits)) {
					for _, fix := range fixEdits[message] {
						accumulated = merge(filename, message, accumulated, fix[filename])
					}
				}
				check("all fixes", accumulated, want)
			}
		}
	}

	return results
}

// applyDiffsAndCompare applies edits to original and compares the results against
// want after formatting both. fileName is use solely for error reporting.
func applyDiffsAndCompare(pkg *types.Package, filename string, original, want []byte, edits []diff.Edit) error {
	// Relativize filename, for tidier errors.
	if cwd, err := os.Getwd(); err == nil {
		if rel, err := filepath.Rel(cwd, filename); err == nil {
			filename = rel
		}
	}

	if len(edits) == 0 {
		return fmt.Errorf("%s: no edits", filename)
	}
	fixedBytes, err := diff.ApplyBytes(original, edits)
	if err != nil {
		return fmt.Errorf("%s: error applying fixes: %v (see possible explanations at RunWithSuggestedFixes)", filename, err)
	}
	fixed, err := driverutil.FormatSourceRemoveImports(pkg, fixedBytes)
	if err != nil {
		return fmt.Errorf("%s: error formatting resulting source: %v\n%s", filename, err, fixedBytes)
	}

	want, err = format.Source(want)
	if err != nil {
		return fmt.Errorf("%s.golden: error formatting golden file: %v\n%s", filename, err, fixed)
	}

	// Keep error reporting logic below consistent with
	// TestScript in ../internal/checker/fix_test.go!

	unified := func(xlabel, ylabel string, x, y []byte) string {
		x = append(slices.Clip(bytes.TrimSpace(x)), '\n')
		y = append(slices.Clip(bytes.TrimSpace(y)), '\n')
		return diff.Unified(xlabel, ylabel, string(x), string(y))
	}

	if diff := unified(filename+" (fixed)", filename+" (want)", fixed, want); diff != "" {
		return fmt.Errorf("unexpected %s content:\n"+
			"-- original --\n%s\n"+
			"-- fixed --\n%s\n"+
			"-- want --\n%s\n"+
			"-- diff original fixed --\n%s\n"+
			"-- diff fixed want --\n%s",
			filename,
			original,
			fixed,
			want,
			unified(filename+" (original)", filename+" (fixed)", original, fixed),
			diff)
	}
	return nil
}

// Run applies an analysis to the packages denoted by the "go list" patterns.
//
// It loads the packages from the specified
// directory using golang.org/x/tools/go/packages, runs the analysis on
// them, and checks that each analysis emits the expected diagnostics
// and facts specified by the contents of '// want ...' comments in the
// package's source files. It treats a comment of the form
// "//...// want..." or "/*...// want... */" as if it starts at 'want'.
//
// If the directory contains a go.mod file, Run treats it as the root of the
// Go module in which to work. Otherwise, Run treats it as the root of a
// GOPATH-style tree, with package contained in the src subdirectory.
//
// An expectation of a Diagnostic is specified by a string literal
// containing a regular expression that must match the diagnostic
// message. For example:
//
//	fmt.Printf("%s", 1) // want `cannot provide int 1 to %s`
//
// An expectation of a Fact associated with an object is specified by
// 'name:"pattern"', where name is the name of the object, which must be
// declared on the same line as the comment, and pattern is a regular
// expression that must match the string representation of the fact,
// fmt.Sprint(fact). For example:
//
//	func panicf(format string, args interface{}) { // want panicf:"printfWrapper"
//
// Package facts are specified by the name "package" and appear on
// line 1 of the first source file of the package.
//
// A single 'want' comment may contain a mixture of diagnostic and fact
// expectations, including multiple facts about the same object:
//
//	// want "diag" "diag2" x:"fact1" x:"fact2" y:"fact3"
//
// Unexpected diagnostics and facts, and unmatched expectations, are
// reported as errors to the Testing.
//
// Run reports an error to the Testing if loading or analysis failed.
// Run also returns a Result for each package for which analysis was
// attempted, even if unsuccessful. It is safe for a test to ignore all
// the results, but a test may use it to perform additional checks.
func Run(t Testing, dir string, a *analysis.Analyzer, patterns ...string) []*Result {
	if t, ok := t.(testing.TB); ok {
		testenv.NeedsGoPackages(t)
	}

	pkgs, err := loadPackages(dir, patterns...)
	if err != nil {
		t.Errorf("loading %s: %v", patterns, err)
		return nil
	}

	// Print parse and type errors to the test log.
	// (Do not print them to stderr, which would pollute
	// the log in cases where the tests pass.)
	if t, ok := t.(testing.TB); ok && !a.RunDespiteErrors {
		packages.Visit(pkgs, nil, func(pkg *packages.Package) {
			for _, err := range pkg.Errors {
				t.Log(err)
			}
		})
	}

	res, err := checker.Analyze([]*analysis.Analyzer{a}, pkgs, nil)
	if err != nil {
		t.Errorf("Analyze: %v", err)
		return nil
	}

	var results []*Result
	for _, act := range res.Roots {
		if act.Err != nil {
			t.Errorf("error analyzing %s: %v", act, act.Err)
		} else {
			check(t, dir, act)
		}

		// Compute legacy map of facts relating to this package.
		facts := make(map[types.Object][]analysis.Fact)
		for _, objFact := range act.AllObjectFacts() {
			if obj := objFact.Object; obj.Pkg() == act.Package.Types {
				facts[obj] = append(facts[obj], objFact.Fact)
			}
		}
		for _, pkgFact := range act.AllPackageFacts() {
			if pkgFact.Package == act.Package.Types {
				facts[nil] = append(facts[nil], pkgFact.Fact)
			}
		}

		// Construct the legacy result.
		results = append(results, &Result{
			Pass:        internal.ActionPass(act), // may be nil
			Diagnostics: act.Diagnostics,
			Facts:       facts,
			Result:      act.Result,
			Err:         act.Err,
			Action:      act,
		})
	}
	return results
}

// A Result holds the result of applying an analyzer to a package.
//
// Facts contains only facts associated with the package and its objects.
//
// This internal type was inadvertently and regrettably exposed
// through a public type alias. It is essentially redundant with
// [checker.Action], but must be retained for compatibility. Clients may
// access the public fields of the Pass but must not invoke any of
// its "verbs", since the pass is already complete.
type Result struct {
	Action *checker.Action

	// legacy fields (do not use)
	Facts       map[types.Object][]analysis.Fact // nil key => package fact
	Pass        *analysis.Pass                   // nil => action not executed
	Diagnostics []analysis.Diagnostic            // see Action.Diagnostics
	Result      any                              // see Action.Result
	Err         error                            // see Action.Err
}

// loadPackages uses go/packages to load a specified packages (from source, with
// dependencies) from dir, which is the root of a GOPATH-style project tree.
// loadPackages returns an error if any package had an error, or the pattern
// matched no packages.
func loadPackages(dir string, patterns ...string) ([]*packages.Package, error) {
	env := []string{"GOPATH=" + dir, "GO111MODULE=off", "GOWORK=off"} // GOPATH mode

	// Undocumented module mode. Will be replaced by something better.
	if _, err := os.Stat(filepath.Join(dir, "go.mod")); err == nil {
		gowork := filepath.Join(dir, "go.work")
		if _, err := os.Stat(gowork); err != nil {
			gowork = "off"
		}

		env = []string{"GO111MODULE=on", "GOPROXY=off", "GOWORK=" + gowork} // module mode
	}

	// packages.Load loads the real standard library, not a minimal
	// fake version, which would be more efficient, especially if we
	// have many small tests that import, say, net/http.
	// However there is no easy way to make go/packages to consume
	// a list of packages we generate and then do the parsing and
	// typechecking, though this feature seems to be a recurring need.

	mode := packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles | packages.NeedImports |
		packages.NeedTypes | packages.NeedTypesSizes | packages.NeedSyntax | packages.NeedTypesInfo |
		packages.NeedDeps | packages.NeedModule
	cfg := &packages.Config{
		Mode:  mode,
		Dir:   dir,
		Tests: true,
		Env:   append(os.Environ(), env...),
	}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		return nil, err
	}

	// If any named package couldn't be loaded at all
	// (e.g. the Name field is unset), fail fast.
	for _, pkg := range pkgs {
		if pkg.Name == "" {
			return nil, fmt.Errorf("failed to load %q: Errors=%v",
				pkg.PkgPath, pkg.Errors)
		}
	}

	if len(pkgs) == 0 {
		return nil, fmt.Errorf("no packages matched %s", patterns)
	}
	return pkgs, nil
}

// check inspects an analysis pass on which the analysis has already
// been run, and verifies that all reported diagnostics and facts match
// specified by the contents of "// want ..." comments in the package's
// source files, which must have been parsed with comments enabled.
func check(t Testing, gopath string, act *checker.Action) {
	type key struct {
		file string
		line int
	}

	want := make(map[key][]expectation)

	// processComment parses expectations out of comments.
	processComment := func(filename string, linenum int, text string) {
		text = strings.TrimSpace(text)

		// Any comment starting with "want" is treated
		// as an expectation, even without following whitespace.
		if rest, ok := strings.CutPrefix(text, "want"); ok {
			lineDelta, expects, err := parseExpectations(rest)
			if err != nil {
				t.Errorf("%s:%d: in 'want' comment: %s", filename, linenum, err)
				return
			}
			if expects != nil {
				want[key{filename, linenum + lineDelta}] = expects
			}
		}
	}

	// Extract 'want' comments from parsed Go files.
	for _, f := range act.Package.Syntax {
		for _, cgroup := range f.Comments {
			for _, c := range cgroup.List {

				text := strings.TrimPrefix(c.Text, "//")
				if text == c.Text { // not a //-comment.
					text = strings.TrimPrefix(text, "/*")
					text = strings.TrimSuffix(text, "*/")
				}

				// Hack: treat a comment of the form "//...// want..."
				// or "/*...// want... */
				// as if it starts at 'want'.
				// This allows us to add comments on comments,
				// as required when testing the buildtag analyzer.
				if i := strings.Index(text, "// want"); i >= 0 {
					text = text[i+len("// "):]
				}

				// It's tempting to compute the filename
				// once outside the loop, but it's
				// incorrect because it can change due
				// to //line directives.
				posn := act.Package.Fset.Position(c.Pos())
				filename := sanitize(gopath, posn.Filename)
				processComment(filename, posn.Line, text)
			}
		}
	}

	// Extract 'want' comments from non-Go files.
	// TODO(adonovan): we may need to handle //line directives.
	files := act.Package.OtherFiles

	// Hack: these analyzers need to extract expectations from
	// all configurations, so include the files are usually
	// ignored. (This was previously a hack in the respective
	// analyzers' tests.)
	switch act.Analyzer.Name {
	case "buildtag", "directive", "plusbuild":
		files = slices.Concat(files, act.Package.IgnoredFiles)
	}

	for _, filename := range files {
		data, err := os.ReadFile(filename)
		if err != nil {
			t.Errorf("can't read '// want' comments from %s: %v", filename, err)
			continue
		}
		filename := sanitize(gopath, filename)
		linenum := 0
		for line := range strings.SplitSeq(string(data), "\n") {
			linenum++

			// Hack: treat a comment of the form "//...// want..."
			// or "/*...// want... */
			// as if it starts at 'want'.
			// This allows us to add comments on comments,
			// as required when testing the buildtag analyzer.
			if i := strings.Index(line, "// want"); i >= 0 {
				line = line[i:]
			}

			if i := strings.Index(line, "//"); i >= 0 {
				line = line[i+len("//"):]
				processComment(filename, linenum, line)
			}
		}
	}

	checkMessage := func(posn token.Position, kind, name, message string) {
		posn.Filename = sanitize(gopath, posn.Filename)
		k := key{posn.Filename, posn.Line}
		expects := want[k]
		var unmatched []string
		for i, exp := range expects {
			if exp.kind == kind && exp.name == name {
				if exp.rx.MatchString(message) {
					// matched: remove the expectation.
					expects[i] = expects[len(expects)-1]
					expects = expects[:len(expects)-1]
					want[k] = expects
					return
				}
				unmatched = append(unmatched, fmt.Sprintf("%#q", exp.rx))
			}
		}
		if unmatched == nil {
			t.Errorf("%v: unexpected %s: %v", posn, kind, message)
		} else {
			t.Errorf("%v: %s %q does not match pattern %s",
				posn, kind, message, strings.Join(unmatched, " or "))
		}
	}

	// Check the diagnostics match expectations.
	for _, f := range act.Diagnostics {
		// TODO(matloob): Support ranges in analysistest.
		posn := act.Package.Fset.Position(f.Pos)
		checkMessage(posn, "diagnostic", "", f.Message)
	}

	// Check the facts match expectations.
	// We check only facts relating to the current package.
	//
	// We report errors in lexical order for determinism.
	// (It's only deterministic within each file, not across files,
	// because go/packages does not guarantee file.Pos is ascending
	// across the files of a single compilation unit.)

	// package facts: reported at start of first file
	for _, pkgFact := range act.AllPackageFacts() {
		if pkgFact.Package == act.Package.Types {
			posn := act.Package.Fset.Position(act.Package.Syntax[0].Pos())
			posn.Line, posn.Column = 1, 1
			checkMessage(posn, "fact", "package", fmt.Sprint(pkgFact))
		}
	}

	// object facts: reported at line of object declaration
	objFacts := act.AllObjectFacts()
	sort.Slice(objFacts, func(i, j int) bool {
		return objFacts[i].Object.Pos() < objFacts[j].Object.Pos()
	})
	for _, objFact := range objFacts {
		if obj := objFact.Object; obj.Pkg() == act.Package.Types {
			posn := act.Package.Fset.Position(obj.Pos())
			checkMessage(posn, "fact", obj.Name(), fmt.Sprint(objFact.Fact))
		}
	}

	// Reject surplus expectations.
	//
	// Sometimes an Analyzer reports two similar diagnostics on a
	// line with only one expectation. The reader may be confused by
	// the error message.
	// TODO(adonovan): print a better error:
	// "got 2 diagnostics here; each one needs its own expectation".
	var surplus []string
	for key, expects := range want {
		for _, exp := range expects {
			err := fmt.Sprintf("%s:%d: no %s was reported matching %#q", key.file, key.line, exp.kind, exp.rx)
			surplus = append(surplus, err)
		}
	}
	sort.Strings(surplus)
	for _, err := range surplus {
		t.Errorf("%s", err)
	}
}

type expectation struct {
	kind string // either "fact" or "diagnostic"
	name string // name of object to which fact belongs, or "package" ("fact" only)
	rx   *regexp.Regexp
}

func (ex expectation) String() string {
	return fmt.Sprintf("%s %s:%q", ex.kind, ex.name, ex.rx) // for debugging
}

// parseExpectations parses the content of a "// want ..." comment
// and returns the expectations, a mixture of diagnostics ("rx") and
// facts (name:"rx").
func parseExpectations(text string) (lineDelta int, expects []expectation, err error) {
	var scanErr string
	sc := new(scanner.Scanner).Init(strings.NewReader(text))
	sc.Error = func(s *scanner.Scanner, msg string) {
		scanErr = msg // e.g. bad string escape
	}
	sc.Mode = scanner.ScanIdents | scanner.ScanStrings | scanner.ScanRawStrings | scanner.ScanInts

	scanRegexp := func(tok rune) (*regexp.Regexp, error) {
		if tok != scanner.String && tok != scanner.RawString {
			return nil, fmt.Errorf("got %s, want regular expression",
				scanner.TokenString(tok))
		}
		pattern, _ := strconv.Unquote(sc.TokenText()) // can't fail
		return regexp.Compile(pattern)
	}

	for {
		tok := sc.Scan()
		switch tok {
		case '+':
			tok = sc.Scan()
			if tok != scanner.Int {
				return 0, nil, fmt.Errorf("got +%s, want +Int", scanner.TokenString(tok))
			}
			lineDelta, _ = strconv.Atoi(sc.TokenText())
		case scanner.String, scanner.RawString:
			rx, err := scanRegexp(tok)
			if err != nil {
				return 0, nil, err
			}
			expects = append(expects, expectation{"diagnostic", "", rx})

		case scanner.Ident:
			name := sc.TokenText()
			tok = sc.Scan()
			if tok != ':' {
				return 0, nil, fmt.Errorf("got %s after %s, want ':'",
					scanner.TokenString(tok), name)
			}
			tok = sc.Scan()
			rx, err := scanRegexp(tok)
			if err != nil {
				return 0, nil, err
			}
			expects = append(expects, expectation{"fact", name, rx})

		case scanner.EOF:
			if scanErr != "" {
				return 0, nil, fmt.Errorf("%s", scanErr)
			}
			return lineDelta, expects, nil

		default:
			return 0, nil, fmt.Errorf("unexpected %s", scanner.TokenString(tok))
		}
	}
}

// sanitize removes the GOPATH portion of the filename,
// typically a gnarly /tmp directory, and returns the rest.
func sanitize(gopath, filename string) string {
	prefix := gopath + string(os.PathSeparator) + "src" + string(os.PathSeparator)
	return filepath.ToSlash(strings.TrimPrefix(filename, prefix))
}


================================================
FILE: go/analysis/analysistest/analysistest_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysistest_test

import (
	"fmt"
	"go/token"
	"log"
	"os"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/findcall"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func init() {
	// Run() decides when tests use GOPATH mode or modules.
	// We turn off GOPROXY just for good measure.
	if err := os.Setenv("GOPROXY", "off"); err != nil {
		log.Fatal(err)
	}
}

// TestTheTest tests the analysistest testing infrastructure.
func TestTheTest(t *testing.T) {
	testenv.NeedsTool(t, "go")

	// We'll simulate a partly failing test of the findcall analysis,
	// which (by default) reports calls to functions named 'println'.
	findcall.Analyzer.Flags.Set("name", "println")

	filemap := map[string]string{
		"a/b.go": `package main // want package:"found"

func main() {
	// The expectation is ill-formed:
	print() // want: "diagnostic"
	print() // want foo"fact"
	print() // want foo:
	print() // want "\xZZ scan error"

	// A diagnostic is reported at this line, but the expectation doesn't match:
	println("hello, world") // want "wrong expectation text"

	// An unexpected diagnostic is reported at this line:
	println() // trigger an unexpected diagnostic

	// No diagnostic is reported at this line:
	print()	// want "unsatisfied expectation"

	// OK
	println("hello, world") // want "call of println"

	// OK /* */-form.
	println("안녕, 세계") /* want "call of println" */

	// OK  (nested comment)
	println("Γειά σου, Κόσμε") // some comment // want "call of println"

	// OK (nested comment in /**/)
	println("你好，世界") /* some comment // want "call of println" */

	// OK (multiple expectations on same line)
	println(); println() // want "call of println(...)" "call of println(...)"

	// A Line that is not formatted correctly in the golden file.
}

// OK (facts and diagnostics on same line)
func println(...interface{}) { println() } // want println:"found" "call of println(...)"

`,
		"a/b.go.golden": `package main // want package:"found"

func main() {
	// The expectation is ill-formed:
	print() // want: "diagnostic"
	print() // want foo"fact"
	print() // want foo:
	print() // want "\xZZ scan error"

	// A diagnostic is reported at this line, but the expectation doesn't match:
	println_TEST_("hello, world") // want "wrong expectation text"

	// An unexpected diagnostic is reported at this line:
	println_TEST_() // trigger an unexpected diagnostic

	// No diagnostic is reported at this line:
	print() // want "unsatisfied expectation"

	// OK
	println_TEST_("hello, world") // want "call of println"

	// OK /* */-form.
	println_TEST_("안녕, 세계") /* want "call of println" */

	// OK  (nested comment)
	println_TEST_("Γειά σου, Κόσμε") // some comment // want "call of println"

	// OK (nested comment in /**/)
	println_TEST_("你好，世界") /* some comment // want "call of println" */

	// OK (multiple expectations on same line)
	println_TEST_()
	println_TEST_() // want "call of println(...)" "call of println(...)"
	
			// A Line that is not formatted correctly in the golden file.
}

// OK (facts and diagnostics on same line)
func println(...interface{}) { println_TEST_() } // want println:"found" "call of println(...)"
`,
		"a/b_test.go": `package main

// Test file shouldn't mess with things (issue #40574)
`,
	}
	dir, cleanup, err := analysistest.WriteFiles(filemap)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()

	var got []string
	t2 := errorfunc(func(s string) { got = append(got, s) }) // a fake *testing.T
	analysistest.RunWithSuggestedFixes(t2, dir, findcall.Analyzer, "a")

	want := []string{
		`a/b.go:5: in 'want' comment: unexpected ":"`,
		`a/b.go:6: in 'want' comment: got String after foo, want ':'`,
		`a/b.go:7: in 'want' comment: got EOF, want regular expression`,
		`a/b.go:8: in 'want' comment: invalid char escape`,
		"a/b.go:11:9: diagnostic \"call of println(...)\" does not match pattern `wrong expectation text`",
		`a/b.go:14:9: unexpected diagnostic: call of println(...)`,
		"a/b.go:11: no diagnostic was reported matching `wrong expectation text`",
		"a/b.go:17: no diagnostic was reported matching `unsatisfied expectation`",
		// duplicate copies of each message from the test package (see issue #40574)
		`a/b.go:5: in 'want' comment: unexpected ":"`,
		`a/b.go:6: in 'want' comment: got String after foo, want ':'`,
		`a/b.go:7: in 'want' comment: got EOF, want regular expression`,
		`a/b.go:8: in 'want' comment: invalid char escape`,
		"a/b.go:11:9: diagnostic \"call of println(...)\" does not match pattern `wrong expectation text`",
		`a/b.go:14:9: unexpected diagnostic: call of println(...)`,
		"a/b.go:11: no diagnostic was reported matching `wrong expectation text`",
		"a/b.go:17: no diagnostic was reported matching `unsatisfied expectation`",
	}
	if !reflect.DeepEqual(got, want) {
		t.Errorf("got:\n%s\nwant:\n%s",
			strings.Join(got, "\n"),
			strings.Join(want, "\n"))
	}
}

// TestNoEnd tests that a missing SuggestedFix.End position is
// correctly interpreted as if equal to SuggestedFix.Pos (see issue #64199).
func TestNoEnd(t *testing.T) {
	noend := &analysis.Analyzer{
		Name: "noend",
		Doc:  "inserts /*hello*/ before first decl",
		Run: func(pass *analysis.Pass) (any, error) {
			decl := pass.Files[0].Decls[0]
			pass.Report(analysis.Diagnostic{
				Pos:     decl.Pos(),
				End:     token.NoPos,
				Message: "say hello",
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: "say hello",
					TextEdits: []analysis.TextEdit{
						{
							Pos:     decl.Pos(),
							End:     token.NoPos,
							NewText: []byte("/*hello*/"),
						},
					},
				}},
			})
			return nil, nil
		},
	}

	filemap := map[string]string{
		"a/a.go": `package a

func F() {} // want "say hello"`,
		"a/a.go.golden": `package a

/*hello*/
func F() {} // want "say hello"`,
	}
	dir, cleanup, err := analysistest.WriteFiles(filemap)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()

	analysistest.RunWithSuggestedFixes(t, dir, noend, "a")
}

func TestModule(t *testing.T) {
	const content = `
Test that analysis.pass.Module is populated.

-- go.mod --
module golang.org/fake/mod

go 1.21

require golang.org/xyz/fake v0.12.34

-- mod.go --
// We expect a module.Path and a module.GoVersion, but an empty module.Version.

package mod // want "golang.org/fake/mod,,1.21"

import "golang.org/xyz/fake/ver"

var _ ver.T

-- vendor/modules.txt --
# golang.org/xyz/fake v0.12.34
## explicit; go 1.18
golang.org/xyz/fake/ver

-- vendor/golang.org/xyz/fake/ver/ver.go --
// This package is vendored so that we can populate a non-empty
// Pass.Module.Version is in a test.

package ver //want "golang.org/xyz/fake,v0.12.34,1.18"

type T string
`
	fs, err := txtar.FS(txtar.Parse([]byte(content)))
	if err != nil {
		t.Fatal(err)
	}
	dir := testfiles.CopyToTmp(t, fs)

	filever := &analysis.Analyzer{
		Name: "mod",
		Doc:  "reports module information",
		Run: func(pass *analysis.Pass) (any, error) {
			msg := "no module info"
			if m := pass.Module; m != nil {
				msg = fmt.Sprintf("%s,%s,%s", m.Path, m.Version, m.GoVersion)
			}
			for _, file := range pass.Files {
				pass.Reportf(file.Package, "%s", msg)
			}
			return nil, nil
		},
	}
	analysistest.Run(t, dir, filever, "golang.org/fake/mod", "golang.org/xyz/fake/ver")
}

type errorfunc func(string)

func (f errorfunc) Errorf(format string, args ...any) {
	f(fmt.Sprintf(format, args...))
}


================================================
FILE: go/analysis/checker/checker.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package checker provides an analysis driver based on the
// [golang.org/x/tools/go/packages] representation of a set of
// packages and all their dependencies, as produced by
// [packages.Load].
//
// It is the core of multichecker (the multi-analyzer driver),
// singlechecker (the single-analyzer driver often used to provide a
// convenient command alongside each analyzer), and analysistest, the
// test driver.
//
// By contrast, the 'go vet' command is based on unitchecker, an
// analysis driver that uses separate analysis--analogous to separate
// compilation--with file-based intermediate results. Like separate
// compilation, it is more scalable, especially for incremental
// analysis of large code bases. Commands based on multichecker and
// singlechecker are capable of detecting when they are being invoked
// by "go vet -vettool=exe" and instead dispatching to unitchecker.
//
// Programs built using this package will, in general, not be usable
// in that way. This package is intended only for use in applications
// that invoke the analysis driver as a subroutine, and need to insert
// additional steps before or after the analysis.
//
// See the Example of how to build a complete analysis driver program.
package checker

import (
	"bytes"
	"encoding/gob"
	"fmt"
	"go/types"
	"io"
	"iter"
	"log"
	"os"
	"reflect"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/internal"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/analysis/driverutil"
)

// Options specifies options that control the analysis driver.
type Options struct {
	// These options correspond to existing flags exposed by multichecker:
	Sequential  bool      // disable parallelism
	SanityCheck bool      // check fact encoding is ok and deterministic
	FactLog     io.Writer // if non-nil, log each exported fact to it

	// TODO(adonovan): expose ReadFile so that an Overlay specified
	// in the [packages.Config] can be communicated via
	// Pass.ReadFile to each Analyzer.
	readFile driverutil.ReadFileFunc
}

// Graph holds the results of a round of analysis, including the graph
// of requested actions (analyzers applied to packages) plus any
// dependent actions that it was necessary to compute.
type Graph struct {
	// Roots contains the roots of the action graph.
	// Each node (a, p) in the action graph represents the
	// application of one analyzer a to one package p.
	// (A node thus corresponds to one analysis.Pass instance.)
	// Roots holds one action per element of the product
	// of the analyzers × packages arguments to Analyze,
	// in unspecified order.
	//
	// Each element of Action.Deps represents an edge in the
	// action graph: a dependency from one action to another.
	// An edge of the form (a, p) -> (a, p2) indicates that the
	// analysis of package p requires information ("facts") from
	// the same analyzer applied to one of p's dependencies, p2.
	// An edge of the form (a, p) -> (a2, p) indicates that the
	// analysis of package p requires information ("results")
	// from a different analyzer a2 applied to the same package.
	// These two kind of edges are called "vertical" and "horizontal",
	// respectively.
	Roots []*Action
}

// All returns an iterator over the action graph in depth-first postorder.
//
// Example:
//
//	for act := range graph.All() {
//		...
//	}
func (g *Graph) All() iter.Seq[*Action] {
	return func(yield func(*Action) bool) {
		forEach(g.Roots, func(act *Action) error {
			if !yield(act) {
				return io.EOF // any error will do
			}
			return nil
		}) // ignore error
	}
}

// An Action represents one unit of analysis work by the driver: the
// application of one analysis to one package. It provides the inputs
// to and records the outputs of a single analysis.Pass.
//
// Actions form a DAG, both within a package (as different analyzers
// are applied, either in sequence or parallel), and across packages
// (as dependencies are analyzed).
type Action struct {
	Analyzer    *analysis.Analyzer
	Package     *packages.Package
	IsRoot      bool // whether this is a root node of the graph
	Deps        []*Action
	Result      any   // computed result of Analyzer.run, if any (and if IsRoot)
	Err         error // error result of Analyzer.run
	Diagnostics []analysis.Diagnostic
	Duration    time.Duration // execution time of this step

	opts         *Options
	once         sync.Once
	pass         *analysis.Pass
	objectFacts  map[objectFactKey]analysis.Fact
	packageFacts map[packageFactKey]analysis.Fact
}

func (act *Action) String() string {
	return fmt.Sprintf("%s@%s", act.Analyzer, act.Package)
}

// Analyze runs the specified analyzers on the initial packages.
//
// The initial packages and all dependencies must have been loaded
// using the [packages.LoadAllSyntax] flag, Analyze may need to run
// some analyzer (those that consume and produce facts) on
// dependencies too.
//
// On success, it returns a Graph of actions whose Roots hold one
// item per (a, p) in the cross-product of analyzers and pkgs.
//
// If opts is nil, it is equivalent to new(Options).
func Analyze(analyzers []*analysis.Analyzer, pkgs []*packages.Package, opts *Options) (*Graph, error) {
	if opts == nil {
		opts = new(Options)
	}

	if err := analysis.Validate(analyzers); err != nil {
		return nil, err
	}

	// Construct the action graph.
	//
	// Each graph node (action) is one unit of analysis.
	// Edges express package-to-package (vertical) dependencies,
	// and analysis-to-analysis (horizontal) dependencies.
	type key struct {
		a   *analysis.Analyzer
		pkg *packages.Package
	}
	actions := make(map[key]*Action)

	var mkAction func(a *analysis.Analyzer, pkg *packages.Package) *Action
	mkAction = func(a *analysis.Analyzer, pkg *packages.Package) *Action {
		k := key{a, pkg}
		act, ok := actions[k]
		if !ok {
			act = &Action{Analyzer: a, Package: pkg, opts: opts}

			// Add a dependency on each required analyzers.
			for _, req := range a.Requires {
				act.Deps = append(act.Deps, mkAction(req, pkg))
			}

			// An analysis that consumes/produces facts
			// must run on the package's dependencies too.
			if len(a.FactTypes) > 0 {
				paths := make([]string, 0, len(pkg.Imports))
				for path := range pkg.Imports {
					paths = append(paths, path)
				}
				sort.Strings(paths) // for determinism
				for _, path := range paths {
					dep := mkAction(a, pkg.Imports[path])
					act.Deps = append(act.Deps, dep)
				}
			}

			actions[k] = act
		}
		return act
	}

	// Build nodes for initial packages.
	var roots []*Action
	for _, a := range analyzers {
		for _, pkg := range pkgs {
			root := mkAction(a, pkg)
			root.IsRoot = true
			roots = append(roots, root)
		}
	}

	// Execute the graph in parallel.
	execAll(roots)

	// Ensure that only root Results are visible to caller.
	// (The others are considered temporary intermediaries.)
	// TODO(adonovan): opt: clear them earlier, so we can
	// release large data structures like SSA sooner.
	for _, act := range actions {
		if !act.IsRoot {
			act.Result = nil
		}
	}

	return &Graph{Roots: roots}, nil
}

func init() {
	// Allow analysistest to access Action.pass,
	// for the legacy analysistest.Result data type,
	// and for internal/checker.ApplyFixes to access pass.ReadFile.
	internal.ActionPass = func(x any) *analysis.Pass { return x.(*Action).pass }
}

type objectFactKey struct {
	obj types.Object
	typ reflect.Type
}

type packageFactKey struct {
	pkg *types.Package
	typ reflect.Type
}

func execAll(actions []*Action) {
	var wg sync.WaitGroup
	for _, act := range actions {
		wg.Add(1)
		work := func(act *Action) {
			act.exec()
			wg.Done()
		}
		if act.opts.Sequential {
			work(act)
		} else {
			go work(act)
		}
	}
	wg.Wait()
}

func (act *Action) exec() { act.once.Do(act.execOnce) }

func (act *Action) execOnce() {
	// Analyze dependencies.
	execAll(act.Deps)

	// Record time spent in this node but not its dependencies.
	// In parallel mode, due to GC/scheduler contention, the
	// time is 5x higher than in sequential mode, even with a
	// semaphore limiting the number of threads here.
	// So use -debug=tp.
	t0 := time.Now()
	defer func() { act.Duration = time.Since(t0) }()

	// Report an error if any dependency failed.
	var failed []string
	for _, dep := range act.Deps {
		if dep.Err != nil {
			failed = append(failed, dep.String())
		}
	}
	if failed != nil {
		sort.Strings(failed)
		act.Err = fmt.Errorf("failed prerequisites: %s", strings.Join(failed, ", "))
		return
	}

	// Plumb the output values of the dependencies
	// into the inputs of this action.  Also facts.
	inputs := make(map[*analysis.Analyzer]any)
	act.objectFacts = make(map[objectFactKey]analysis.Fact)
	act.packageFacts = make(map[packageFactKey]analysis.Fact)
	for _, dep := range act.Deps {
		if dep.Package == act.Package {
			// Same package, different analysis (horizontal edge):
			// in-memory outputs of prerequisite analyzers
			// become inputs to this analysis pass.
			inputs[dep.Analyzer] = dep.Result
		} else if dep.Analyzer == act.Analyzer { // (always true)
			// Same analysis, different package (vertical edge):
			// serialized facts produced by prerequisite analysis
			// become available to this analysis pass.
			inheritFacts(act, dep)
		}
	}

	// Quick (nonexhaustive) check that the correct go/packages mode bits were used.
	// (If there were errors, all bets are off.)
	if pkg := act.Package; pkg.Errors == nil {
		if pkg.Name == "" || pkg.PkgPath == "" || pkg.Types == nil || pkg.Fset == nil || pkg.TypesSizes == nil {
			panic("packages must be loaded with packages.LoadSyntax mode")
		}
	}

	module := &analysis.Module{} // possibly empty (non nil) in go/analysis drivers.
	if mod := act.Package.Module; mod != nil {
		module = analysisModuleFromPackagesModule(mod)
	}

	// Run the analysis.
	pass := &analysis.Pass{
		Analyzer:     act.Analyzer,
		Fset:         act.Package.Fset,
		Files:        act.Package.Syntax,
		OtherFiles:   act.Package.OtherFiles,
		IgnoredFiles: act.Package.IgnoredFiles,
		Pkg:          act.Package.Types,
		TypesInfo:    act.Package.TypesInfo,
		TypesSizes:   act.Package.TypesSizes,
		TypeErrors:   act.Package.TypeErrors,
		Module:       module,

		ResultOf: inputs,
		Report: func(d analysis.Diagnostic) {
			// Assert that SuggestedFixes are well formed.
			if err := driverutil.ValidateFixes(act.Package.Fset, act.Analyzer, d.SuggestedFixes); err != nil {
				panic(err)
			}
			act.Diagnostics = append(act.Diagnostics, d)
		},
		ImportObjectFact:  act.ObjectFact,
		ExportObjectFact:  act.exportObjectFact,
		ImportPackageFact: act.PackageFact,
		ExportPackageFact: act.exportPackageFact,
		AllObjectFacts:    act.AllObjectFacts,
		AllPackageFacts:   act.AllPackageFacts,
	}
	readFile := os.ReadFile
	if act.opts.readFile != nil {
		readFile = act.opts.readFile
	}
	pass.ReadFile = driverutil.CheckedReadFile(pass, readFile)
	act.pass = pass

	act.Result, act.Err = func() (any, error) {
		if act.Package.IllTyped && !pass.Analyzer.RunDespiteErrors {
			return nil, fmt.Errorf("analysis skipped due to errors in package")
		}

		result, err := pass.Analyzer.Run(pass)
		if err != nil {
			return nil, err
		}

		// correct result type?
		if got, want := reflect.TypeOf(result), pass.Analyzer.ResultType; got != want {
			return nil, fmt.Errorf(
				"internal error: on package %s, analyzer %s returned a result of type %v, but declared ResultType %v",
				pass.Pkg.Path(), pass.Analyzer, got, want)
		}

		// resolve diagnostic URLs
		for i := range act.Diagnostics {
			url, err := driverutil.ResolveURL(act.Analyzer, act.Diagnostics[i])
			if err != nil {
				return nil, err
			}
			act.Diagnostics[i].URL = url
		}
		return result, nil
	}()

	// Help detect (disallowed) calls after Run.
	pass.ExportObjectFact = nil
	pass.ExportPackageFact = nil
}

// inheritFacts populates act.facts with
// those it obtains from its dependency, dep.
func inheritFacts(act, dep *Action) {
	for key, fact := range dep.objectFacts {
		// Filter out facts related to objects
		// that are irrelevant downstream
		// (equivalently: not in the compiler export data).
		if !exportedFrom(key.obj, dep.Package.Types) {
			if false {
				log.Printf("%v: discarding %T fact from %s for %s: %s", act, fact, dep, key.obj, fact)
			}
			continue
		}

		// Optionally serialize/deserialize fact
		// to verify that it works across address spaces.
		if act.opts.SanityCheck {
			encodedFact, err := codeFact(fact)
			if err != nil {
				log.Panicf("internal error: encoding of %T fact failed in %v", fact, act)
			}
			fact = encodedFact
		}

		if false {
			log.Printf("%v: inherited %T fact for %s: %s", act, fact, key.obj, fact)
		}
		act.objectFacts[key] = fact
	}

	for key, fact := range dep.packageFacts {
		// TODO: filter out facts that belong to
		// packages not mentioned in the export data
		// to prevent side channels.
		//
		// The Pass.All{Object,Package}Facts accessors expose too much:
		// all facts, of all types, for all dependencies in the action
		// graph. Not only does the representation grow quadratically,
		// but it violates the separate compilation paradigm, allowing
		// analysis implementations to communicate with indirect
		// dependencies that are not mentioned in the export data.
		//
		// It's not clear how to fix this short of a rather expensive
		// filtering step after each action that enumerates all the
		// objects that would appear in export data, and deletes
		// facts associated with objects not in this set.

		// Optionally serialize/deserialize fact
		// to verify that it works across address spaces
		// and is deterministic.
		if act.opts.SanityCheck {
			encodedFact, err := codeFact(fact)
			if err != nil {
				log.Panicf("internal error: encoding of %T fact failed in %v", fact, act)
			}
			fact = encodedFact
		}

		if false {
			log.Printf("%v: inherited %T fact for %s: %s", act, fact, key.pkg.Path(), fact)
		}
		act.packageFacts[key] = fact
	}
}

// codeFact encodes then decodes a fact,
// just to exercise that logic.
func codeFact(fact analysis.Fact) (analysis.Fact, error) {
	// We encode facts one at a time.
	// A real modular driver would emit all facts
	// into one encoder to improve gob efficiency.
	var buf bytes.Buffer
	if err := gob.NewEncoder(&buf).Encode(fact); err != nil {
		return nil, err
	}

	// Encode it twice and assert that we get the same bits.
	// This helps detect nondeterministic Gob encoding (e.g. of maps).
	var buf2 bytes.Buffer
	if err := gob.NewEncoder(&buf2).Encode(fact); err != nil {
		return nil, err
	}
	if !bytes.Equal(buf.Bytes(), buf2.Bytes()) {
		return nil, fmt.Errorf("encoding of %T fact is nondeterministic", fact)
	}

	new := reflect.New(reflect.TypeOf(fact).Elem()).Interface().(analysis.Fact)
	if err := gob.NewDecoder(&buf).Decode(new); err != nil {
		return nil, err
	}
	return new, nil
}

// exportedFrom reports whether obj may be visible to a package that imports pkg.
// This includes not just the exported members of pkg, but also unexported
// constants, types, fields, and methods, perhaps belonging to other packages,
// that find there way into the API.
// This is an overapproximation of the more accurate approach used by
// gc export data, which walks the type graph, but it's much simpler.
//
// TODO(adonovan): do more accurate filtering by walking the type graph.
func exportedFrom(obj types.Object, pkg *types.Package) bool {
	switch obj := obj.(type) {
	case *types.Func:
		return obj.Exported() && obj.Pkg() == pkg ||
			obj.Signature().Recv() != nil
	case *types.Var:
		if obj.IsField() {
			return true
		}
		// we can't filter more aggressively than this because we need
		// to consider function parameters exported, but have no way
		// of telling apart function parameters from local variables.
		return obj.Pkg() == pkg
	case *types.TypeName, *types.Const:
		return true
	}
	return false // Nil, Builtin, Label, or PkgName
}

// ObjectFact retrieves a fact associated with obj,
// and returns true if one was found.
// Given a value ptr of type *T, where *T satisfies Fact,
// ObjectFact copies the value to *ptr.
//
// See documentation at ImportObjectFact field of [analysis.Pass].
func (act *Action) ObjectFact(obj types.Object, ptr analysis.Fact) bool {
	if obj == nil {
		panic("nil object")
	}
	key := objectFactKey{obj, factType(ptr)}
	if v, ok := act.objectFacts[key]; ok {
		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
		return true
	}
	return false
}

// exportObjectFact implements Pass.ExportObjectFact.
func (act *Action) exportObjectFact(obj types.Object, fact analysis.Fact) {
	if act.pass.ExportObjectFact == nil {
		log.Panicf("%s: Pass.ExportObjectFact(%s, %T) called after Run", act, obj, fact)
	}

	if obj.Pkg() != act.Package.Types {
		log.Panicf("internal error: in analysis %s of package %s: Fact.Set(%s, %T): can't set facts on objects belonging another package",
			act.Analyzer, act.Package, obj, fact)
	}

	key := objectFactKey{obj, factType(fact)}
	act.objectFacts[key] = fact // clobber any existing entry
	if log := act.opts.FactLog; log != nil {
		objstr := types.ObjectString(obj, (*types.Package).Name)
		fmt.Fprintf(log, "%s: object %s has fact %s\n",
			act.Package.Fset.Position(obj.Pos()), objstr, fact)
	}
}

// AllObjectFacts returns a new slice containing all object facts of
// the analysis's FactTypes in unspecified order.
//
// See documentation at AllObjectFacts field of [analysis.Pass].
func (act *Action) AllObjectFacts() []analysis.ObjectFact {
	facts := make([]analysis.ObjectFact, 0, len(act.objectFacts))
	for k, fact := range act.objectFacts {
		facts = append(facts, analysis.ObjectFact{Object: k.obj, Fact: fact})
	}
	return facts
}

// PackageFact retrieves a fact associated with package pkg,
// which must be this package or one of its dependencies.
//
// See documentation at ImportObjectFact field of [analysis.Pass].
func (act *Action) PackageFact(pkg *types.Package, ptr analysis.Fact) bool {
	if pkg == nil {
		panic("nil package")
	}
	key := packageFactKey{pkg, factType(ptr)}
	if v, ok := act.packageFacts[key]; ok {
		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
		return true
	}
	return false
}

// exportPackageFact implements Pass.ExportPackageFact.
func (act *Action) exportPackageFact(fact analysis.Fact) {
	if act.pass.ExportPackageFact == nil {
		log.Panicf("%s: Pass.ExportPackageFact(%T) called after Run", act, fact)
	}

	key := packageFactKey{act.pass.Pkg, factType(fact)}
	act.packageFacts[key] = fact // clobber any existing entry
	if log := act.opts.FactLog; log != nil {
		fmt.Fprintf(log, "%s: package %s has fact %s\n",
			act.Package.Fset.Position(act.pass.Files[0].Pos()), act.pass.Pkg.Path(), fact)
	}
}

func factType(fact analysis.Fact) reflect.Type {
	t := reflect.TypeOf(fact)
	if t.Kind() != reflect.Pointer {
		log.Fatalf("invalid Fact type: got %T, want pointer", fact)
	}
	return t
}

// AllPackageFacts returns a new slice containing all package
// facts of the analysis's FactTypes in unspecified order.
//
// See documentation at AllPackageFacts field of [analysis.Pass].
func (act *Action) AllPackageFacts() []analysis.PackageFact {
	facts := make([]analysis.PackageFact, 0, len(act.packageFacts))
	for k, fact := range act.packageFacts {
		facts = append(facts, analysis.PackageFact{Package: k.pkg, Fact: fact})
	}
	return facts
}

// forEach is a utility function for traversing the action graph. It
// applies function f to each action in the graph reachable from
// roots, in depth-first postorder. If any call to f returns an error,
// the traversal is aborted and ForEach returns the error.
func forEach(roots []*Action, f func(*Action) error) error {
	seen := make(map[*Action]bool)
	var visitAll func(actions []*Action) error
	visitAll = func(actions []*Action) error {
		for _, act := range actions {
			if !seen[act] {
				seen[act] = true
				if err := visitAll(act.Deps); err != nil {
					return err
				}
				if err := f(act); err != nil {
					return err
				}
			}
		}
		return nil
	}
	return visitAll(roots)
}

func analysisModuleFromPackagesModule(mod *packages.Module) *analysis.Module {
	if mod == nil {
		return nil
	}

	var modErr *analysis.ModuleError
	if mod.Error != nil {
		modErr = &analysis.ModuleError{
			Err: mod.Error.Err,
		}
	}

	return &analysis.Module{
		Path:      mod.Path,
		Version:   mod.Version,
		Replace:   analysisModuleFromPackagesModule(mod.Replace),
		Time:      mod.Time,
		Main:      mod.Main,
		Indirect:  mod.Indirect,
		Dir:       mod.Dir,
		GoMod:     mod.GoMod,
		GoVersion: mod.GoVersion,
		Error:     modErr,
	}
}


================================================
FILE: go/analysis/checker/checker_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package checker_test

import (
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/checker"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

// TestPassModule checks that an analyzer observes the correct Pass.Module
// fields (GoMod, Dir, Path, Main, GoVersion) when run on a module.
func TestPassModule(t *testing.T) {
	testenv.NeedsGoPackages(t)

	const src = `
-- go.mod --
module example.com/hello
go 1.13

-- hello.go --
package hello
`
	dir, err := os.MkdirTemp("", "")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(dir)

	fs, err := txtar.FS(txtar.Parse([]byte(src)))
	if err != nil {
		t.Fatal(err)
	}
	if err := os.CopyFS(dir, fs); err != nil {
		t.Fatal(err)
	}

	// Capture the Module seen by the analyzer.
	var got *analysis.Module
	testAnalyzer := &analysis.Analyzer{
		Name: "testmodule",
		Doc:  "Captures Pass.Module for testing.",
		Run: func(pass *analysis.Pass) (any, error) {
			got = pass.Module
			return nil, nil
		},
	}

	cfg := &packages.Config{
		Mode: packages.LoadAllSyntax | packages.NeedModule,
		Dir:  dir,
	}
	pkgs, err := packages.Load(cfg, "example.com/hello")
	if err != nil {
		t.Fatal(err)
	}

	if _, err := checker.Analyze([]*analysis.Analyzer{testAnalyzer}, pkgs, nil); err != nil {
		t.Fatal(err)
	}

	if got == nil {
		t.Fatal("Pass.Module is nil")
	}
	if got.Path != "example.com/hello" {
		t.Errorf("Pass.Module.Path = %q, want %q", got.Path, "example.com/hello")
	}
	if !got.Main {
		t.Errorf("Pass.Module.Main = false, want true")
	}
	wantGoMod := filepath.Join(dir, "go.mod")
	if got.GoMod != wantGoMod {
		t.Errorf("Pass.Module.GoMod = %q, want %q", got.GoMod, wantGoMod)
	}
	if got.Dir != dir {
		t.Errorf("Pass.Module.Dir = %q, want %q", got.Dir, dir)
	}
	if got.GoVersion != "1.13" {
		t.Errorf("Pass.Module.GoVersion = %q, want %q", got.GoVersion, "1.13")
	}
}


================================================
FILE: go/analysis/checker/example_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !wasm

// The example command demonstrates a simple go/packages-based
// analysis driver program.
package checker_test

import (
	"fmt"
	"log"
	"maps"
	"os"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/checker"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/txtar"
)

const testdata = `
-- go.mod --
module example.com
go 1.21

-- a/a.go --
package a

import _ "example.com/b"
import _ "example.com/c"

func A1()
func A2()
func A3()

-- b/b.go --
package b

func B1()
func B2()

-- c/c.go --
package c

import _ "example.com/d"

func C1()

-- d/d.go --
package d

func D1()
func D2()
func D3()
func D4()
`

func Example() {
	// Extract a tree of Go source files.
	// (Avoid the standard library as it is always evolving.)
	dir, err := os.MkdirTemp("", "")
	if err != nil {
		log.Fatal(err)
	}
	fs, err := txtar.FS(txtar.Parse([]byte(testdata)))
	if err != nil {
		log.Fatal(err)
	}
	if err := os.CopyFS(dir, fs); err != nil {
		log.Fatal(err)
	}

	// Load packages: example.com/a + dependencies
	//
	cfg := &packages.Config{Mode: packages.LoadAllSyntax, Dir: dir}
	initial, err := packages.Load(cfg, "example.com/a")
	if err != nil {
		log.Fatal(err) // failure to enumerate packages
	}

	// There may be parse or type errors among the
	// initial packages or their dependencies,
	// but the analysis driver can handle faulty inputs,
	// as can some analyzers.
	packages.PrintErrors(initial)

	if len(initial) == 0 {
		log.Fatalf("no initial packages")
	}

	// Run analyzers (just one) on example.com packages.
	analyzers := []*analysis.Analyzer{pkgdecls}
	graph, err := checker.Analyze(analyzers, initial, nil)
	if err != nil {
		log.Fatal(err)
	}

	// Inspect the result of each analysis action,
	// including those for all dependencies.
	//
	// A realistic client would use Result, Err, Diagnostics,
	// but for test stability, we just print the action string
	// ("analyzer@package").
	for act := range graph.All() {
		fmt.Println("printing", act)
	}

	// Print the package fact for the sole initial package.
	root := graph.Roots[0]
	fact := new(pkgdeclsFact)
	if root.PackageFact(root.Package.Types, fact) {
		for k, v := range fact.numdecls {
			fmt.Printf("%s:\t%d decls\n", k, v)
		}
	}

	// Unordered Output:
	// printing pkgdecls@example.com/a
	// printing pkgdecls@example.com/b
	// printing pkgdecls@example.com/c
	// printing pkgdecls@example.com/d
	// example.com/a:	3 decls
	// example.com/b:	2 decls
	// example.com/c:	1 decls
	// example.com/d:	4 decls
}

// pkgdecls is a trivial example analyzer that uses package facts to
// compute information from the entire dependency graph.
var pkgdecls = &analysis.Analyzer{
	Name:      "pkgdecls",
	Doc:       "Computes a package fact mapping each package to its number of declarations.",
	Run:       run,
	FactTypes: []analysis.Fact{(*pkgdeclsFact)(nil)},
}

type pkgdeclsFact struct{ numdecls map[string]int }

func (*pkgdeclsFact) AFact() {}

func run(pass *analysis.Pass) (any, error) {
	numdecls := map[string]int{
		pass.Pkg.Path(): pass.Pkg.Scope().Len(),
	}

	// Compute the union across all dependencies.
	for _, imp := range pass.Pkg.Imports() {
		if depFact := new(pkgdeclsFact); pass.ImportPackageFact(imp, depFact) {
			maps.Copy(numdecls, depFact.numdecls)
		}
	}

	pass.ExportPackageFact(&pkgdeclsFact{numdecls})

	return nil, nil
}


================================================
FILE: go/analysis/checker/print.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package checker

// This file defines helpers for printing analysis results.
// They should all be pure functions.

import (
	"bytes"
	"fmt"
	"go/token"
	"io"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/driverutil"
)

// PrintText emits diagnostics as plain text to w.
//
// If contextLines is nonnegative, it also prints the
// offending line, plus that many lines of context
// before and after the line.
func (g *Graph) PrintText(w io.Writer, contextLines int) error {
	return writeTextDiagnostics(w, g.Roots, contextLines)
}

func writeTextDiagnostics(w io.Writer, roots []*Action, contextLines int) error {
	// De-duplicate diagnostics by position (not token.Pos) to
	// avoid double-reporting in source files that belong to
	// multiple packages, such as foo and foo.test.
	// (We cannot assume that such repeated files were parsed
	// only once and use syntax nodes as the key.)
	type key struct {
		pos token.Position
		end token.Position
		*analysis.Analyzer
		message string
	}
	seen := make(map[key]bool)

	// TODO(adonovan): opt: plumb errors back from PrintPlain and avoid buffer.
	buf := new(bytes.Buffer)
	forEach(roots, func(act *Action) error {
		if act.Err != nil {
			fmt.Fprintf(w, "%s: %v\n", act.Analyzer.Name, act.Err)
		} else if act.IsRoot {
			for _, diag := range act.Diagnostics {
				// We don't display Analyzer.Name/diag.Category
				// as most users don't care.

				posn := act.Package.Fset.Position(diag.Pos)
				end := act.Package.Fset.Position(diag.End)
				k := key{posn, end, act.Analyzer, diag.Message}
				if seen[k] {
					continue // duplicate
				}
				seen[k] = true

				driverutil.PrintPlain(buf, act.Package.Fset, contextLines, diag)
			}
		}
		return nil
	})
	_, err := w.Write(buf.Bytes())
	return err
}

// PrintJSON emits diagnostics in JSON form to w.
// Diagnostics are shown only for the root nodes,
// but errors (if any) are shown for all dependencies.
func (g *Graph) PrintJSON(w io.Writer) error {
	return writeJSONDiagnostics(w, g.Roots)
}

func writeJSONDiagnostics(w io.Writer, roots []*Action) error {
	tree := make(driverutil.JSONTree)
	forEach(roots, func(act *Action) error {
		var diags []analysis.Diagnostic
		if act.IsRoot {
			diags = act.Diagnostics
		}
		tree.Add(act.Package.Fset, act.Package.ID, act.Analyzer.Name, diags, act.Err)
		return nil
	})
	return tree.Print(w)
}


================================================
FILE: go/analysis/diagnostic.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysis

import "go/token"

// A Diagnostic is a message associated with a source location or range.
//
// An Analyzer may return a variety of diagnostics; the optional Category,
// which should be a constant, may be used to classify them.
// It is primarily intended to make it easy to look up documentation.
//
// All Pos values are interpreted relative to Pass.Fset. If End is
// provided, the diagnostic is specified to apply to the range between
// Pos and End.
type Diagnostic struct {
	Pos      token.Pos
	End      token.Pos // optional
	Category string    // optional
	Message  string

	// URL is the optional location of a web page that provides
	// additional documentation for this diagnostic.
	//
	// If URL is empty but a Category is specified, then the
	// Analysis driver should treat the URL as "#"+Category.
	//
	// The URL may be relative. If so, the base URL is that of the
	// Analyzer that produced the diagnostic;
	// see https://pkg.go.dev/net/url#URL.ResolveReference.
	URL string

	// SuggestedFixes is an optional list of fixes to address the
	// problem described by the diagnostic. Each one represents an
	// alternative strategy, and should have a distinct and
	// descriptive message; at most one may be applied.
	//
	// Fixes for different diagnostics should be treated as
	// independent changes to the same baseline file state,
	// analogous to a set of git commits all with the same parent.
	// Combining fixes requires resolving any conflicts that
	// arise, analogous to a git merge.
	// Any conflicts that remain may be dealt with, depending on
	// the tool, by discarding fixes, consulting the user, or
	// aborting the operation.
	SuggestedFixes []SuggestedFix

	// Related contains optional secondary positions and messages
	// related to the primary diagnostic.
	Related []RelatedInformation
}

// RelatedInformation contains information related to a diagnostic.
// For example, a diagnostic that flags duplicated declarations of a
// variable may include one RelatedInformation per existing
// declaration.
type RelatedInformation struct {
	Pos     token.Pos
	End     token.Pos // optional
	Message string
}

// A SuggestedFix is a code change associated with a Diagnostic that a
// user can choose to apply to their code. Usually the SuggestedFix is
// meant to fix the issue flagged by the diagnostic.
//
// The TextEdits must not overlap, nor contain edits for other
// packages. Edits need not be totally ordered, but the order
// determines how insertions at the same point will be applied.
type SuggestedFix struct {
	// A verb phrase describing the fix, to be shown to
	// a user trying to decide whether to accept it.
	//
	// Example: "Remove the surplus argument"
	Message   string
	TextEdits []TextEdit
}

// A TextEdit represents the replacement of the code between Pos and End with the new text.
// Each TextEdit should apply to a single file. End should not be earlier in the file than Pos.
type TextEdit struct {
	// For a pure insertion, End can either be set to Pos or token.NoPos.
	Pos     token.Pos
	End     token.Pos
	NewText []byte
}


================================================
FILE: go/analysis/doc/suggested_fixes.md
================================================
# Suggested Fixes in the Analysis Framework

## The Purpose of Suggested Fixes

The analysis framework is planned to add a facility to output
suggested fixes. Suggested fixes in the analysis framework
are meant to address two common use cases. The first is the
natural use case of allowing the user to quickly fix errors or issues
pointed out by analyzers through their editor or analysis tool.
An editor, when showing a diagnostic for an issue, can propose
code to fix that issue. Users can accept the proposal and have
the editor apply the fix for them. The second case is to allow
for defining refactorings. An analyzer meant to perform a
refactoring can produce suggested fixes equivalent to the diff
of the refactoring. Then, an analysis driver meant to apply
refactorings can automatically apply all the diffs that
are produced by the analysis as suggested fixes.

## Proposed Suggested Fix API

Suggested fixes will be defined using the following structs:

```go
// A SuggestedFix is a code change associated with a Diagnostic that a user can choose
// to apply to their code. Usually the SuggestedFix is meant to fix the issue flagged
// by the diagnostic.
type SuggestedFix struct {
	// A description for this suggested fix to be shown to a user deciding
	// whether to accept it.
	Message   string
	TextEdits []TextEdit
}

// A TextEdit represents the replacement of the code between Pos and End with the new text.
type TextEdit struct {
	// For a pure insertion, End can either be set to Pos or token.NoPos.
	Pos     token.Pos
	End     token.Pos
	NewText []byte
}
```

A suggested fix needs a message field so it can specify what it will do.
Some analyses may not have clear cut fixes, and a suggested fix may need
to provide additional information to help users specify whether they
should be added.

Suggested fixes are allowed to make multiple
edits in a file, because some logical changes may affect otherwise
unrelated parts of the AST.

A TextEdit specifies a Pos and End: these will usually be the Pos
and End of an AST node that will be replaced.

Finally, the replacements themselves are represented as []bytes.


Suggested fixes themselves will be added as a field in the
Diagnostic struct:

```go

type Diagnostic struct {
	...
	SuggestedFixes []SuggestedFix  // this is an optional field
}

```

### Requirements for SuggestedFixes

SuggestedFixes will be required to conform to several requirements:

* TextEdits for a SuggestedFix should not overlap.
* TextEdits for SuggestedFixes should not contain edits for other packages.
* Each TextEdit should apply to a single file.

These requirements guarantee that suggested fixes can be cleanly applied.
Because a driver may only analyze, or be able to modify, the current package,
we restrict edits to the current package. In general this restriction should
not be a big problem for users because other packages might not belong to the
same module and so will not be safe to modify in a single change.

On the other hand, analyzers will not be required to produce gofmt-compliant
code. Analysis drivers will be expected to apply gofmt to the results of
a SuggestedFix application.

## SuggestedFix integration points

### ```checker -fix```

Singlechecker and multichecker have the ```-fix``` flag, which will automatically
apply all fixes suggested by their analysis or analyses. This is intended to
be used primarily by refactoring tools, because in general, like diagnostics,
suggested fixes will need to be examined by a human who can decide whether
they are relevant.

### gopls

Suggested fixes have been integrated into ```gopls```, and editors can choose
to display the suggested fixes to the user as they type, so that they can be
accepted to fix diagnostics immediately.

### Code Review Tools (Future Work)

Suggested fixes can be integrated into programs that are integrated with
code review systems to suggest fixes that users can apply from their code review tools.

## Alternatives

### Performing transformations directly on the AST

Even though it may be more convenient
for authors of refactorings to perform transformations directly on
the AST, allowing mutations on the AST would mean that a copy of the AST
would need to be made every time a transformation was produced, to avoid
having transformations interfere with each other.

This is primarily an issue with the current design of the Go AST and
it's possible that a new future version of the AST might make this a more
viable option.

### Supplying AST nodes directly

Another possibility would be for SuggestedFixes to supply the replacement
ASTs directly. There is one primary limitation to this: that because
comments to ASTs specify their location using token.Pos values, it's very
difficult to place any comments in the right place.

In general, it's also more difficult to generate the AST structures for
some code than to generate the text for that code. So we prefer to allow
the flexibility to do the latter.

Because users can call ```format.Node``` to produce the text for any
AST node, users will always be able to produce a SuggestedFix from AST
nodes. In future, we may choose to add a convenience method that does this for users.


================================================
FILE: go/analysis/doc.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package analysis defines the interface between a modular static
analysis and an analysis driver program.

# Background

A static analysis is a function that inspects a package of Go code and
reports a set of diagnostics (typically mistakes in the code), and
perhaps produces other results as well, such as suggested refactorings
or other facts. An analysis that reports mistakes is informally called a
"checker". For example, the printf checker reports mistakes in
fmt.Printf format strings.

A "modular" analysis is one that inspects one package at a time but can
save information from a lower-level package and use it when inspecting a
higher-level package, analogous to separate compilation in a toolchain.
The printf checker is modular: when it discovers that a function such as
log.Fatalf delegates to fmt.Printf, it records this fact, and checks
calls to that function too, including calls made from another package.

By implementing a common interface, checkers from a variety of sources
can be easily selected, incorporated, and reused in a wide range of
driver programs including command-line tools (such as vet), text editors and
IDEs, build and test systems (such as go build, Bazel, or Buck), test
frameworks, code review tools, code-base indexers (such as SourceGraph),
documentation viewers (such as godoc), batch pipelines for large code
bases, and so on.

# Analyzer

The primary type in the API is [Analyzer]. An Analyzer statically
describes an analysis function: its name, documentation, flags,
relationship to other analyzers, and of course, its logic.

To define an analysis, a user declares a (logically constant) variable
of type Analyzer. Here is a typical example from one of the analyzers in
the go/analysis/passes/ subdirectory:

	package unusedresult

	var Analyzer = &analysis.Analyzer{
		Name: "unusedresult",
		Doc:  "check for unused results of calls to some functions",
		Run:  run,
		...
	}

	func run(pass *analysis.Pass) (interface{}, error) {
		...
	}

An analysis driver is a program such as vet that runs a set of
analyses and prints the diagnostics that they report.
The driver program must import the list of Analyzers it needs.
Typically each Analyzer resides in a separate package.
To add a new Analyzer to an existing driver, add another item to the list:

	import ( "unusedresult"; "nilness"; "printf" )

	var analyses = []*analysis.Analyzer{
		unusedresult.Analyzer,
		nilness.Analyzer,
		printf.Analyzer,
	}

A driver may use the name, flags, and documentation to provide on-line
help that describes the analyses it performs.
The doc comment contains a brief one-line summary,
optionally followed by paragraphs of explanation.

The [Analyzer] type has more fields besides those shown above:

	type Analyzer struct {
		Name             string
		Doc              string
		Flags            flag.FlagSet
		Run              func(*Pass) (interface{}, error)
		RunDespiteErrors bool
		ResultType       reflect.Type
		Requires         []*Analyzer
		FactTypes        []Fact
	}

The Flags field declares a set of named (global) flag variables that
control analysis behavior. Unlike vet, analysis flags are not declared
directly in the command line FlagSet; it is up to the driver to set the
flag variables. A driver for a single analysis, a, might expose its flag
f directly on the command line as -f, whereas a driver for multiple
analyses might prefix the flag name by the analysis name (-a.f) to avoid
ambiguity. An IDE might expose the flags through a graphical interface,
and a batch pipeline might configure them from a config file.
See the "findcall" analyzer for an example of flags in action.

The RunDespiteErrors flag indicates whether the analysis is equipped to
handle ill-typed code. If not, the driver will skip the analysis if
there were parse or type errors.
The optional ResultType field specifies the type of the result value
computed by this analysis and made available to other analyses.
The Requires field specifies a list of analyses upon which
this one depends and whose results it may access, and it constrains the
order in which a driver may run analyses.
The FactTypes field is discussed in the section on Modularity.
The analysis package provides a Validate function to perform basic
sanity checks on an Analyzer, such as that its Requires graph is
acyclic, its fact and result types are unique, and so on.

Finally, the Run field contains a function to be called by the driver to
execute the analysis on a single package. The driver passes it an
instance of the Pass type.

# Pass

A [Pass] describes a single unit of work: the application of a particular
Analyzer to a particular package of Go code.
The Pass provides information to the Analyzer's Run function about the
package being analyzed, and provides operations to the Run function for
reporting diagnostics and other information back to the driver.

	type Pass struct {
		Fset         *token.FileSet
		Files        []*ast.File
		OtherFiles   []string
		IgnoredFiles []string
		Pkg          *types.Package
		TypesInfo    *types.Info
		ResultOf     map[*Analyzer]interface{}
		Report       func(Diagnostic)
		...
	}

The Fset, Files, Pkg, and TypesInfo fields provide the syntax trees,
type information, and source positions for a single package of Go code.

The OtherFiles field provides the names of non-Go
files such as assembly that are part of this package.
Similarly, the IgnoredFiles field provides the names of Go and non-Go
source files that are not part of this package with the current build
configuration but may be part of other build configurations.
The contents of these files may be read using Pass.ReadFile;
see the "asmdecl" or "buildtags" analyzers for examples of loading
non-Go files and reporting diagnostics against them.

The ResultOf field provides the results computed by the analyzers
required by this one, as expressed in its Analyzer.Requires field. The
driver runs the required analyzers first and makes their results
available in this map. Each Analyzer must return a value of the type
described in its Analyzer.ResultType field.
For example, the "ctrlflow" analyzer returns a *ctrlflow.CFGs, which
provides a control-flow graph for each function in the package (see
golang.org/x/tools/go/cfg); the "inspect" analyzer returns a value that
enables other Analyzers to traverse the syntax trees of the package more
efficiently; and the "buildssa" analyzer constructs an SSA-form
intermediate representation.
Each of these Analyzers extends the capabilities of later Analyzers
without adding a dependency to the core API, so an analysis tool pays
only for the extensions it needs.

The Report function emits a diagnostic, a message associated with a
source position. For most analyses, diagnostics are their primary
result.
For convenience, Pass provides a helper method, Reportf, to report a new
diagnostic by formatting a string.
Diagnostic is defined as:

	type Diagnostic struct {
		Pos      token.Pos
		Category string // optional
		Message  string
	}

The optional Category field is a short identifier that classifies the
kind of message when an analysis produces several kinds of diagnostic.

The [Diagnostic] struct does not have a field to indicate its severity
because opinions about the relative importance of Analyzers and their
diagnostics vary widely among users. The design of this framework does
not hold each Analyzer responsible for identifying the severity of its
diagnostics. Instead, we expect that drivers will allow the user to
customize the filtering and prioritization of diagnostics based on the
producing Analyzer and optional Category, according to the user's
preferences.

Most Analyzers inspect typed Go syntax trees, but a few, such as asmdecl
and buildtag, inspect the raw text of Go source files or even non-Go
files such as assembly. To report a diagnostic against a line of a
raw text file, use the following sequence:

	content, err := pass.ReadFile(filename)
	if err != nil { ... }
	tf := fset.AddFile(filename, -1, len(content))
	tf.SetLinesForContent(content)
	...
	pass.Reportf(tf.LineStart(line), "oops")

# Modular analysis with Facts

To improve efficiency and scalability, large programs are routinely
built using separate compilation: units of the program are compiled
separately, and recompiled only when one of their dependencies changes;
independent modules may be compiled in parallel. The same technique may
be applied to static analyses, for the same benefits. Such analyses are
described as "modular".

A compiler’s type checker is an example of a modular static analysis.
Many other checkers we would like to apply to Go programs can be
understood as alternative or non-standard type systems. For example,
vet's printf checker infers whether a function has the "printf wrapper"
type, and it applies stricter checks to calls of such functions. In
addition, it records which functions are printf wrappers for use by
later analysis passes to identify other printf wrappers by induction.
A result such as “f is a printf wrapper” that is not interesting by
itself but serves as a stepping stone to an interesting result (such as
a diagnostic) is called a [Fact].

The analysis API allows an analysis to define new types of facts, to
associate facts of these types with objects (named entities) declared
within the current package, or with the package as a whole, and to query
for an existing fact of a given type associated with an object or
package.

An Analyzer that uses facts must declare their types:

	var Analyzer = &analysis.Analyzer{
		Name:      "printf",
		FactTypes: []analysis.Fact{new(isWrapper)},
		...
	}

	type isWrapper struct{} // => *types.Func f “is a printf wrapper”

The driver program ensures that facts for a pass’s dependencies are
generated before analyzing the package and is responsible for propagating
facts from one package to another, possibly across address spaces.
Consequently, Facts must be serializable. The API requires that drivers
use the gob encoding, an efficient, robust, self-describing binary
protocol. A fact type may implement the GobEncoder/GobDecoder interfaces
if the default encoding is unsuitable. Facts should be stateless.
Because serialized facts may appear within build outputs, the gob encoding
of a fact must be deterministic, to avoid spurious cache misses in
build systems that use content-addressable caches.
The driver makes a single call to the gob encoder for all facts
exported by a given analysis pass, so that the topology of
shared data structures referenced by multiple facts is preserved.

The Pass type has functions to import and export facts,
associated either with an object or with a package:

	type Pass struct {
		...
		ExportObjectFact func(types.Object, Fact)
		ImportObjectFact func(types.Object, Fact) bool

		ExportPackageFact func(fact Fact)
		ImportPackageFact func(*types.Package, Fact) bool
	}

An Analyzer may only export facts associated with the current package or
its objects, though it may import facts from any package or object that
is an import dependency of the current package.

Conceptually, ExportObjectFact(obj, fact) inserts fact into a hidden map keyed by
the pair (obj, TypeOf(fact)), and the ImportObjectFact function
retrieves the entry from this map and copies its value into the variable
pointed to by fact. This scheme assumes that the concrete type of fact
is a pointer; this assumption is checked by the Validate function.
See the "printf" analyzer for an example of object facts in action.

Some driver implementations (such as those based on Bazel and Blaze) do
not currently apply analyzers to packages of the standard library.
Therefore, for best results, analyzer authors should not rely on
analysis facts being available for standard packages.
For example, although the printf checker is capable of deducing during
analysis of the log package that log.Printf is a printf wrapper,
this fact is built in to the analyzer so that it correctly checks
calls to log.Printf even when run in a driver that does not apply
it to standard packages. We would like to remove this limitation in future.

# Testing an Analyzer

The analysistest subpackage provides utilities for testing an Analyzer.
In a few lines of code, it is possible to run an analyzer on a package
of testdata files and check that it reported all the expected
diagnostics and facts (and no more). Expectations are expressed using
"// want ..." comments in the input code.

# Standalone commands

Analyzers are provided in the form of packages that a driver program is
expected to import. The vet command imports a set of several analyzers,
but users may wish to define their own analysis commands that perform
additional checks. To simplify the task of creating an analysis command,
either for a single analyzer or for a whole suite, we provide the
singlechecker and multichecker subpackages.

The singlechecker package provides the main function for a command that
runs one analyzer. By convention, each analyzer such as
go/analysis/passes/findcall should be accompanied by a singlechecker-based
command such as go/analysis/passes/findcall/cmd/findcall, defined in its
entirety as:

	package main

	import (
		"golang.org/x/tools/go/analysis/passes/findcall"
		"golang.org/x/tools/go/analysis/singlechecker"
	)

	func main() { singlechecker.Main(findcall.Analyzer) }

A tool that provides multiple analyzers can use multichecker in a
similar way, giving it the list of Analyzers.
*/
package analysis


================================================
FILE: go/analysis/internal/analysisflags/flags.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package analysisflags defines helpers for processing flags (-help,
// -json, -fix, -diff, etc) common to unitchecker and
// {single,multi}checker. It is not intended for broader use.
package analysisflags

import (
	"crypto/sha256"
	"encoding/gob"
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"strconv"

	"golang.org/x/tools/go/analysis"
)

// flags common to all {single,multi,unit}checkers.
var (
	JSON    = false // -json
	Context = -1    // -c=N: if N>0, display offending line plus N lines of context
	Fix     bool    // -fix
	Diff    bool    // -diff
)

// Parse creates a flag for each of the analyzer's flags,
// including (in multi mode) a flag named after the analyzer,
// parses the flags, then filters and returns the list of
// analyzers enabled by flags.
//
// The result is intended to be passed to unitchecker.Run or checker.Run.
// Use in unitchecker.Run will gob.Register all fact types for the returned
// graph of analyzers but of course not the ones only reachable from
// dropped analyzers. To avoid inconsistency about which gob types are
// registered from run to run, Parse itself gob.Registers all the facts
// only reachable from dropped analyzers.
// This is not a particularly elegant API, but this is an internal package.
func Parse(analyzers []*analysis.Analyzer, multi bool) []*analysis.Analyzer {
	// Connect each analysis flag to the command line as -analysis.flag.
	enabled := make(map[*analysis.Analyzer]*triState)
	for _, a := range analyzers {
		var prefix string

		// Add -NAME flag to enable it.
		if multi {
			prefix = a.Name + "."

			enable := new(triState)
			enableUsage := fmt.Sprintf("enable %q analysis", a.Name)
			flag.Var(enable, a.Name, enableUsage)
			enabled[a] = enable
		}

		a.Flags.VisitAll(func(f *flag.Flag) {
			if !multi && flag.Lookup(f.Name) != nil {
				log.Printf("%s flag -%s would conflict with driver; skipping", a.Name, f.Name)
				return
			}

			name := prefix + f.Name
			flag.Var(f.Value, name, f.Usage)
		})
	}

	// standard flags: -flags, -V.
	printflags := flag.Bool("flags", false, "print analyzer flags in JSON")
	addVersionFlag()

	// flags common to all checkers
	flag.BoolVar(&JSON, "json", JSON, "emit JSON output")
	flag.IntVar(&Context, "c", Context, `display offending line with this many lines of context`)
	flag.BoolVar(&Fix, "fix", false, "apply all suggested fixes")
	flag.BoolVar(&Diff, "diff", false, "with -fix, don't update the files, but print a unified diff")

	// Add shims for legacy vet flags to enable existing
	// scripts that run vet to continue to work.
	_ = flag.Bool("source", false, "no effect (deprecated)")
	_ = flag.Bool("v", false, "no effect (deprecated)")
	_ = flag.Bool("all", false, "no effect (deprecated)")
	_ = flag.String("tags", "", "no effect (deprecated)")
	for old, new := range vetLegacyFlags {
		newFlag := flag.Lookup(new)
		if newFlag != nil && flag.Lookup(old) == nil {
			flag.Var(newFlag.Value, old, "deprecated alias for -"+new)
		}
	}

	flag.Parse() // (ExitOnError)

	// -flags: print flags so that go vet knows which ones are legitimate.
	if *printflags {
		printFlags()
		os.Exit(0)
	}

	everything := expand(analyzers)

	// If any -NAME flag is true,  run only those analyzers. Otherwise,
	// if any -NAME flag is false, run all but those analyzers.
	if multi {
		var hasTrue, hasFalse bool
		for _, ts := range enabled {
			switch *ts {
			case setTrue:
				hasTrue = true
			case setFalse:
				hasFalse = true
			}
		}

		var keep []*analysis.Analyzer
		if hasTrue {
			for _, a := range analyzers {
				if *enabled[a] == setTrue {
					keep = append(keep, a)
				}
			}
			analyzers = keep
		} else if hasFalse {
			for _, a := range analyzers {
				if *enabled[a] != setFalse {
					keep = append(keep, a)
				}
			}
			analyzers = keep
		}
	}

	// Register fact types of skipped analyzers
	// in case we encounter them in imported files.
	kept := expand(analyzers)
	for a := range everything {
		if !kept[a] {
			for _, f := range a.FactTypes {
				gob.Register(f)
			}
		}
	}

	return analyzers
}

func expand(analyzers []*analysis.Analyzer) map[*analysis.Analyzer]bool {
	seen := make(map[*analysis.Analyzer]bool)
	var visitAll func([]*analysis.Analyzer)
	visitAll = func(analyzers []*analysis.Analyzer) {
		for _, a := range analyzers {
			if !seen[a] {
				seen[a] = true
				visitAll(a.Requires)
			}
		}
	}
	visitAll(analyzers)
	return seen
}

func printFlags() {
	type jsonFlag struct {
		Name  string
		Bool  bool
		Usage string
	}
	var flags []jsonFlag = nil
	flag.VisitAll(func(f *flag.Flag) {
		// Don't report {single,multi}checker debugging
		// flags or fix as these have no effect on unitchecker
		// (as invoked by 'go vet').
		switch f.Name {
		case "debug", "cpuprofile", "memprofile", "trace", "fix":
			return
		}

		b, ok := f.Value.(interface{ IsBoolFlag() bool })
		isBool := ok && b.IsBoolFlag()
		flags = append(flags, jsonFlag{f.Name, isBool, f.Usage})
	})
	data, err := json.MarshalIndent(flags, "", "\t")
	if err != nil {
		log.Fatal(err)
	}
	os.Stdout.Write(data)
}

// addVersionFlag registers a -V flag that, if set,
// prints the executable version and exits 0.
//
// If the -V flag already exists — for example, because it was already
// registered by a call to cmd/internal/objabi.AddVersionFlag — then
// addVersionFlag does nothing.
func addVersionFlag() {
	if flag.Lookup("V") == nil {
		flag.Var(versionFlag{}, "V", "print version and exit")
	}
}

// versionFlag minimally complies with the -V protocol required by "go vet".
type versionFlag struct{}

func (versionFlag) IsBoolFlag() bool { return true }
func (versionFlag) Get() any         { return nil }
func (versionFlag) String() string   { return "" }
func (versionFlag) Set(s string) error {
	if s != "full" {
		log.Fatalf("unsupported flag value: -V=%s (use -V=full)", s)
	}

	// This replicates the minimal subset of
	// cmd/internal/objabi.AddVersionFlag, which is private to the
	// go tool yet forms part of our command-line interface.
	// TODO(adonovan): clarify the contract.

	// Print the tool version so the build system can track changes.
	// Formats:
	//   $progname version devel ... buildID=...
	//   $progname version go1.9.1
	progname, err := os.Executable()
	if err != nil {
		return err
	}
	f, err := os.Open(progname)
	if err != nil {
		log.Fatal(err)
	}
	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		log.Fatal(err)
	}
	f.Close()
	fmt.Printf("%s version devel comments-go-here buildID=%02x\n",
		progname, string(h.Sum(nil)))
	os.Exit(0)
	return nil
}

// A triState is a boolean that knows whether
// it has been set to either true or false.
// It is used to identify whether a flag appears;
// the standard boolean flag cannot
// distinguish missing from unset.
// It also satisfies flag.Value.
type triState int

const (
	unset triState = iota
	setTrue
	setFalse
)

// triState implements flag.Value, flag.Getter, and flag.boolFlag.
// They work like boolean flags: we can say vet -printf as well as vet -printf=true
func (ts *triState) Get() any {
	return *ts == setTrue
}

func (ts *triState) Set(value string) error {
	b, err := strconv.ParseBool(value)
	if err != nil {
		// This error message looks poor but package "flag" adds
		// "invalid boolean value %q for -NAME: %s"
		return fmt.Errorf("want true or false")
	}
	if b {
		*ts = setTrue
	} else {
		*ts = setFalse
	}
	return nil
}

func (ts *triState) String() string {
	switch *ts {
	case unset:
		return "true"
	case setTrue:
		return "true"
	case setFalse:
		return "false"
	}
	panic("not reached")
}

func (ts triState) IsBoolFlag() bool {
	return true
}

// Legacy flag support

// vetLegacyFlags maps flags used by legacy vet to their corresponding
// new names. The old names will continue to work.
var vetLegacyFlags = map[string]string{
	// Analyzer name changes
	"bool":       "bools",
	"buildtags":  "buildtag",
	"methods":    "stdmethods",
	"rangeloops": "loopclosure",

	// Analyzer flags
	"compositewhitelist":  "composites.whitelist",
	"printfuncs":          "printf.funcs",
	"shadowstrict":        "shadow.strict",
	"unusedfuncs":         "unusedresult.funcs",
	"unusedstringmethods": "unusedresult.stringmethods",
}


================================================
FILE: go/analysis/internal/analysisflags/flags_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysisflags_test

import (
	"fmt"
	"os"
	"os/exec"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
)

func main() {
	fmt.Println(analysisflags.Parse([]*analysis.Analyzer{
		{Name: "a1", Doc: "a1"},
		{Name: "a2", Doc: "a2"},
		{Name: "a3", Doc: "a3"},
	}, true))
	os.Exit(0)
}

// This test fork/execs the main function above.
func TestExec(t *testing.T) {
	if runtime.GOOS != "linux" {
		t.Skipf("skipping fork/exec test on this platform")
	}

	progname := os.Args[0]

	if os.Getenv("ANALYSISFLAGS_CHILD") == "1" {
		// child process
		os.Args = strings.Fields(progname + " " + os.Getenv("FLAGS"))
		main()
		panic("unreachable")
	}

	for _, test := range []struct {
		flags string
		want  string // output should contain want
	}{
		{"", "[a1 a2 a3]"},
		{"-a1=0", "[a2 a3]"},
		{"-a1=1", "[a1]"},
		{"-a1", "[a1]"},
		{"-a1=1 -a3=1", "[a1 a3]"},
		{"-a1=1 -a3=0", "[a1]"},
		{"-V=full", "analysisflags.test version devel"},
	} {
		cmd := exec.Command(progname, "-test.run=TestExec")
		cmd.Env = append(os.Environ(), "ANALYSISFLAGS_CHILD=1", "FLAGS="+test.flags)

		output, err := cmd.CombinedOutput()
		if err != nil {
			t.Fatalf("exec failed: %v; output=<<%s>>", err, output)
		}

		got := strings.TrimSpace(string(output))
		if !strings.Contains(got, test.want) {
			t.Errorf("got %q, does not contain %q", got, test.want)
		}
	}
}


================================================
FILE: go/analysis/internal/analysisflags/help.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysisflags

import (
	"flag"
	"fmt"
	"log"
	"os"
	"sort"
	"strings"

	"golang.org/x/tools/go/analysis"
)

const help = `PROGNAME is a tool for static analysis of Go programs.

PROGNAME examines Go source code and reports diagnostics for
suspicious constructs or opportunities for improvement.
Diagnostics may include suggested fixes.

An example of a suspicious construct is a Printf call whose arguments
do not align with the format string. Analyzers may use heuristics that
do not guarantee all reports are genuine problems, but can find
mistakes not caught by the compiler.

An example of an opportunity for improvement is a loop over
strings.Split(doc, "\n"), which may be replaced by a loop over the
strings.SplitSeq iterator, avoiding an array allocation.
Diagnostics in such cases may report non-problems,
but should carry fixes that may be safely applied.

For analyzers of the first kind, use "go vet -vettool=PROGRAM"
to run the tool and report diagnostics.

For analyzers of the second kind, use "go fix -fixtool=PROGRAM"
to run the tool and apply the fixes it suggests.
`

// Help implements the help subcommand for a multichecker or unitchecker
// style command. The optional args specify the analyzers to describe.
// Help calls log.Fatal if no such analyzer exists.
func Help(progname string, analyzers []*analysis.Analyzer, args []string) {
	// No args: show summary of all analyzers.
	if len(args) == 0 {
		fmt.Println(strings.ReplaceAll(help, "PROGNAME", progname))
		fmt.Println("Registered analyzers:")
		fmt.Println()
		sort.Slice(analyzers, func(i, j int) bool {
			return analyzers[i].Name < analyzers[j].Name
		})
		for _, a := range analyzers {
			title := strings.Split(a.Doc, "\n\n")[0]
			fmt.Printf("    %-12s %s\n", a.Name, title)
		}
		fmt.Println("\nBy default all analyzers are run.")
		fmt.Println("To select specific analyzers, use the -NAME flag for each one,")
		fmt.Println(" or -NAME=false to run all analyzers not explicitly disabled.")

		// Show only the core command-line flags.
		fmt.Println("\nCore flags:")
		fmt.Println()
		fs := flag.NewFlagSet("", flag.ExitOnError)
		flag.VisitAll(func(f *flag.Flag) {
			if !strings.Contains(f.Name, ".") {
				fs.Var(f.Value, f.Name, f.Usage)
			}
		})
		fs.SetOutput(os.Stdout)
		fs.PrintDefaults()

		fmt.Printf("\nTo see details and flags of a specific analyzer, run '%s help name'.\n", progname)

		return
	}

	// Show help on specific analyzer(s).
outer:
	for _, arg := range args {
		for _, a := range analyzers {
			if a.Name == arg {
				paras := strings.Split(a.Doc, "\n\n")
				title := paras[0]
				fmt.Printf("%s: %s\n", a.Name, title)

				// Show only the flags relating to this analysis,
				// properly prefixed.
				first := true
				fs := flag.NewFlagSet(a.Name, flag.ExitOnError)
				a.Flags.VisitAll(func(f *flag.Flag) {
					if first {
						first = false
						fmt.Println("\nAnalyzer flags:")
						fmt.Println()
					}
					fs.Var(f.Value, a.Name+"."+f.Name, f.Usage)
				})
				fs.SetOutput(os.Stdout)
				fs.PrintDefaults()

				if len(paras) > 1 {
					fmt.Printf("\n%s\n", strings.Join(paras[1:], "\n\n"))
				}

				continue outer
			}
		}
		log.Fatalf("Analyzer %q not registered", arg)
	}
}


================================================
FILE: go/analysis/internal/checker/checker.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package internal/checker defines various implementation helpers for
// the singlechecker and multichecker packages, which provide the
// complete main function for an analysis driver executable
// based on go/packages.
//
// (Note: it is not used by the public 'checker' package, since the
// latter provides a set of pure functions for use as building blocks.)
package checker

// TODO(adonovan): publish the JSON schema in go/analysis or analysisjson.

import (
	"flag"
	"fmt"
	"io"

	"log"
	"os"
	"runtime"
	"runtime/pprof"
	"runtime/trace"
	"sort"
	"strings"
	"time"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/checker"
	"golang.org/x/tools/go/analysis/internal"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/analysis/driverutil"
)

var (
	// Debug is a set of single-letter flags:
	//
	//	f	show [f]acts as they are created
	// 	p	disable [p]arallel execution of analyzers
	//	s	do additional [s]anity checks on fact types and serialization
	//	t	show [t]iming info (NB: use 'p' flag to avoid GC/scheduler noise)
	//	v	show [v]erbose logging
	//
	Debug = ""

	// Log files for optional performance tracing.
	CPUProfile, MemProfile, Trace string

	// IncludeTests indicates whether test files should be analyzed too.
	IncludeTests = true
)

// RegisterFlags registers command-line flags used by the analysis driver.
func RegisterFlags() {
	// When adding flags here, remember to update
	// the list of suppressed flags in analysisflags.

	flag.StringVar(&Debug, "debug", Debug, `debug flags, any subset of "fpstv"`)

	flag.StringVar(&CPUProfile, "cpuprofile", "", "write CPU profile to this file")
	flag.StringVar(&MemProfile, "memprofile", "", "write memory profile to this file")
	flag.StringVar(&Trace, "trace", "", "write trace log to this file")
	flag.BoolVar(&IncludeTests, "test", IncludeTests, "indicates whether test files should be analyzed, too")
}

// Run loads the packages specified by args using go/packages,
// then applies the specified analyzers to them.
// Analysis flags must already have been set.
// Analyzers must be valid according to [analysis.Validate].
// It provides most of the logic for the main functions of both the
// singlechecker and the multi-analysis commands.
// It returns the appropriate exit code.
//
// TODO(adonovan): tests should not call this function directly.
// Fiddling with global variables (flags such as [analysisflags.Fix])
// is error-prone and hostile to parallelism. Instead, use unit tests
// of the actual units (e.g. checker.Analyze) and integration tests
// (e.g. TestScript) of whole executables.
func Run(args []string, analyzers []*analysis.Analyzer) (exitcode int) {
	// Instead of returning a code directly,
	// call this function to monotonically increase the exit code.
	// This allows us to keep going in the face of some errors
	// without having to remember what code to return.
	//
	// TODO(adonovan): interpreting exit codes is like reading tea-leaves.
	// Instead of wasting effort trying to encode a multidimensional result
	// into 7 bits we should just emit structured JSON output, and
	// an exit code of 0 or 1 for success or failure.
	exitAtLeast := func(code int) {
		exitcode = max(code, exitcode)
	}

	// Since analysisflags is linked in (for {single,multi}checker),
	// the -v flag is registered for complex legacy reasons
	// related to cmd/vet CLI.
	// Treat it as an undocumented alias for -debug=v.
	if v := flag.CommandLine.Lookup("v"); v != nil &&
		v.Value.(flag.Getter).Get() == true &&
		!strings.Contains(Debug, "v") {
		Debug += "v"
	}

	if CPUProfile != "" {
		f, err := os.Create(CPUProfile)
		if err != nil {
			log.Fatal(err)
		}
		if err := pprof.StartCPUProfile(f); err != nil {
			log.Fatal(err)
		}
		// NB: profile won't be written in case of error.
		defer pprof.StopCPUProfile()
	}

	if Trace != "" {
		f, err := os.Create(Trace)
		if err != nil {
			log.Fatal(err)
		}
		if err := trace.Start(f); err != nil {
			log.Fatal(err)
		}
		// NB: trace log won't be written in case of error.
		defer func() {
			trace.Stop()
			log.Printf("To view the trace, run:\n$ go tool trace view %s", Trace)
		}()
	}

	if MemProfile != "" {
		f, err := os.Create(MemProfile)
		if err != nil {
			log.Fatal(err)
		}
		// NB: memprofile won't be written in case of error.
		defer func() {
			runtime.GC() // get up-to-date statistics
			if err := pprof.WriteHeapProfile(f); err != nil {
				log.Fatalf("Writing memory profile: %v", err)
			}
			f.Close()
		}()
	}

	// Load the packages.
	if dbg('v') {
		log.SetPrefix("")
		log.SetFlags(log.Lmicroseconds) // display timing
		log.Printf("load %s", args)
	}

	// Optimization: if the selected analyzers don't produce/consume
	// facts, we need source only for the initial packages.
	allSyntax := needFacts(analyzers)
	initial, err := load(args, allSyntax)
	if err != nil {
		log.Print(err)
		exitAtLeast(1)
		return
	}

	// Print package and module errors regardless of RunDespiteErrors.
	// Do not exit if there are errors, yet.
	if n := packages.PrintErrors(initial); n > 0 {
		exitAtLeast(1)
	}

	var factLog io.Writer
	if dbg('f') {
		factLog = os.Stderr
	}

	// Run the analysis.
	opts := &checker.Options{
		SanityCheck: dbg('s'),
		Sequential:  dbg('p'),
		FactLog:     factLog,
	}
	if dbg('v') {
		log.Printf("building graph of analysis passes")
	}
	graph, err := checker.Analyze(analyzers, initial, opts)
	if err != nil {
		log.Print(err)
		exitAtLeast(1)
		return
	}

	// Don't print the diagnostics,
	// but apply all fixes from the root actions.
	if analysisflags.Fix {
		fixActions := make([]driverutil.FixAction, len(graph.Roots))
		for i, act := range graph.Roots {
			if pass := internal.ActionPass(act); pass != nil {
				fixActions[i] = driverutil.FixAction{
					Name:         act.String(),
					Pkg:          act.Package.Types,
					Files:        act.Package.Syntax,
					FileSet:      act.Package.Fset,
					ReadFileFunc: pass.ReadFile,
					Diagnostics:  act.Diagnostics,
				}
			}
		}
		write := func(filename string, content []byte) error {
			return os.WriteFile(filename, content, 0644)
		}
		if err := driverutil.ApplyFixes(fixActions, write, analysisflags.Diff, dbg('v')); err != nil {
			// Fail when applying fixes failed.
			log.Print(err)
			exitAtLeast(1)
			return
		}
		// Don't proceed to print text/JSON,
		// and don't report an error
		// just because there were diagnostics.
		return
	}

	// Print the results. If !RunDespiteErrors and there
	// are errors in the packages, this will have 0 exit
	// code. Otherwise, we prefer to return exit code
	// indicating diagnostics.
	exitAtLeast(printDiagnostics(graph))

	return
}

// printDiagnostics prints diagnostics in text or JSON form
// and returns the appropriate exit code.
func printDiagnostics(graph *checker.Graph) (exitcode int) {
	// Keep consistent with analogous logic in
	// processResults in ../../unitchecker/unitchecker.go.

	// Print the results.
	// With -json, the exit code is always zero.
	if analysisflags.JSON {
		if err := graph.PrintJSON(os.Stdout); err != nil {
			return 1
		}
	} else {
		if err := graph.PrintText(os.Stderr, analysisflags.Context); err != nil {
			return 1
		}

		// Compute the exit code.
		var numErrors, rootDiags int
		for act := range graph.All() {
			if act.Err != nil {
				numErrors++
			} else if act.IsRoot {
				rootDiags += len(act.Diagnostics)
			}
		}

		if numErrors > 0 {
			exitcode = 1 // analysis failed, at least partially
		} else if rootDiags > 0 {
			exitcode = 3 // successfully produced diagnostics
		}
	}

	// Print timing info.
	if dbg('t') {
		if !dbg('p') {
			log.Println("Warning: times are mostly GC/scheduler noise; use -debug=tp to disable parallelism")
		}

		var list []*checker.Action
		var total time.Duration
		for act := range graph.All() {
			list = append(list, act)
			total += act.Duration
		}

		// Print actions accounting for 90% of the total.
		sort.Slice(list, func(i, j int) bool {
			return list[i].Duration > list[j].Duration
		})
		var sum time.Duration
		for _, act := range list {
			fmt.Fprintf(os.Stderr, "%s\t%s\n", act.Duration, act)
			sum += act.Duration
			if sum >= total*9/10 {
				break
			}
		}
		if total > sum {
			fmt.Fprintf(os.Stderr, "%s\tall others\n", total-sum)
		}
	}

	return exitcode
}

// load loads the initial packages. Returns only top-level loading
// errors. Does not consider errors in packages.
func load(patterns []string, allSyntax bool) ([]*packages.Package, error) {
	mode := packages.LoadSyntax
	if allSyntax {
		mode = packages.LoadAllSyntax
	}
	mode |= packages.NeedModule
	conf := packages.Config{
		Mode: mode,
		// Ensure that child process inherits correct alias of PWD.
		// (See discussion at Dir field of [exec.Command].)
		// However, this currently breaks some tests.
		// TODO(adonovan): Investigate.
		//
		// Dir:   os.Getenv("PWD"),
		Tests: IncludeTests,
	}
	initial, err := packages.Load(&conf, patterns...)
	if err == nil && len(initial) == 0 {
		err = fmt.Errorf("%s matched no packages", strings.Join(patterns, " "))
	}
	return initial, err
}

// needFacts reports whether any analysis required by the specified set
// needs facts.  If so, we must load the entire program from source.
func needFacts(analyzers []*analysis.Analyzer) bool {
	seen := make(map[*analysis.Analyzer]bool)
	var q []*analysis.Analyzer // for BFS
	q = append(q, analyzers...)
	for len(q) > 0 {
		a := q[0]
		q = q[1:]
		if !seen[a] {
			seen[a] = true
			if len(a.FactTypes) > 0 {
				return true
			}
			q = append(q, a.Requires...)
		}
	}
	return false
}

func dbg(b byte) bool { return strings.IndexByte(Debug, b) >= 0 }


================================================
FILE: go/analysis/internal/checker/checker_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package checker_test

import (
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/go/analysis/internal/checker"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestApplyFixes(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.RedirectStderr(t) // associated checker.Run output with this test

	files := map[string]string{
		"rename/test.go": `package rename

func Foo() {
	bar := 12
	_ = bar
}

// the end
`}
	want := `package rename

func Foo() {
	baz := 12
	_ = baz
}

// the end
`

	testdata, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	path := filepath.Join(testdata, "src/rename/test.go")

	analysisflags.Fix = true
	checker.Run([]string{"file=" + path}, []*analysis.Analyzer{renameAnalyzer})
	analysisflags.Fix = false

	contents, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}

	got := string(contents)
	if got != want {
		t.Errorf("contents of rewritten file\ngot: %s\nwant: %s", got, want)
	}

	defer cleanup()
}

func TestRunDespiteErrors(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.RedirectStderr(t) // associate checker.Run output with this test

	files := map[string]string{
		"rderr/test.go": `package rderr

// Foo deliberately has a type error
func Foo(s string) int {
	return s + 1
}
`,
		"cperr/test.go": `package copyerr

import "sync"

func bar() { } // for renameAnalyzer

type T struct{ mu sync.Mutex }
type T1 struct{ t *T }

func NewT1() *T1 { return &T1{T} }
`,
	}

	testdata, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()

	rderrFile := "file=" + filepath.Join(testdata, "src/rderr/test.go")
	cperrFile := "file=" + filepath.Join(testdata, "src/cperr/test.go")

	// A no-op analyzer that should finish regardless of
	// parse or type errors in the code.
	noop := &analysis.Analyzer{
		Name:     "noop",
		Doc:      "noop",
		Requires: []*analysis.Analyzer{inspect.Analyzer},
		Run: func(pass *analysis.Pass) (any, error) {
			return nil, nil
		},
		RunDespiteErrors: true,
	}

	// A no-op analyzer, with facts, that should finish
	// regardless of parse or type errors in the code.
	noopWithFact := &analysis.Analyzer{
		Name:     "noopfact",
		Doc:      "noopfact",
		Requires: []*analysis.Analyzer{inspect.Analyzer},
		Run: func(pass *analysis.Pass) (any, error) {
			return nil, nil
		},
		RunDespiteErrors: true,
		FactTypes:        []analysis.Fact{&EmptyFact{}},
	}

	for _, test := range []struct {
		name      string
		pattern   []string
		analyzers []*analysis.Analyzer
		code      int
	}{
		// parse/type errors
		{name: "skip-error", pattern: []string{rderrFile}, analyzers: []*analysis.Analyzer{renameAnalyzer}, code: 1},
		// RunDespiteErrors allows a driver to run an Analyzer even after parse/type errors.
		//
		// The noop analyzer doesn't use facts, so the driver loads only the root
		// package from source. For the rest, it asks 'go list' for export data,
		// which fails because the compiler encounters the type error.  Since the
		// errors come from 'go list', the driver doesn't run the analyzer.
		{name: "despite-error", pattern: []string{rderrFile}, analyzers: []*analysis.Analyzer{noop}, code: exitCodeFailed},
		// The noopfact analyzer does use facts, so the driver loads source for
		// all dependencies, does type checking itself, recognizes the error as a
		// type error, and runs the analyzer.
		{name: "despite-error-fact", pattern: []string{rderrFile}, analyzers: []*analysis.Analyzer{noopWithFact}, code: exitCodeFailed},
		// combination of parse/type errors and no errors
		{name: "despite-error-and-no-error", pattern: []string{rderrFile, "sort"}, analyzers: []*analysis.Analyzer{renameAnalyzer, noop}, code: exitCodeFailed},
		// non-existing package error
		{name: "no-package", pattern: []string{"xyz"}, analyzers: []*analysis.Analyzer{renameAnalyzer}, code: exitCodeFailed},
		{name: "no-package-despite-error", pattern: []string{"abc"}, analyzers: []*analysis.Analyzer{noop}, code: exitCodeFailed},
		{name: "no-multi-package-despite-error", pattern: []string{"xyz", "abc"}, analyzers: []*analysis.Analyzer{noop}, code: exitCodeFailed},
		// combination of type/parsing and different errors
		{name: "different-errors", pattern: []string{rderrFile, "xyz"}, analyzers: []*analysis.Analyzer{renameAnalyzer, noop}, code: exitCodeFailed},
		// non existing dir error
		{name: "no-match-dir", pattern: []string{"file=non/existing/dir"}, analyzers: []*analysis.Analyzer{renameAnalyzer, noop}, code: exitCodeFailed},
		// no errors
		{name: "no-errors", pattern: []string{"sort"}, analyzers: []*analysis.Analyzer{renameAnalyzer, noop}, code: exitCodeSuccess},
		// duplicate list error with no findings
		{name: "list-error", pattern: []string{cperrFile}, analyzers: []*analysis.Analyzer{noop}, code: exitCodeFailed},
		// duplicate list errors with findings (issue #67790)
		{name: "list-error-findings", pattern: []string{cperrFile}, analyzers: []*analysis.Analyzer{renameAnalyzer}, code: exitCodeDiagnostics},
	} {
		t.Run(test.name, func(t *testing.T) {
			if got := checker.Run(test.pattern, test.analyzers); got != test.code {
				t.Errorf("got incorrect exit code %d for test %s; want %d", got, test.name, test.code)
			}
		})
	}
}

type EmptyFact struct{}

func (f *EmptyFact) AFact() {}

func TestURL(t *testing.T) {
	// TestURL test that URLs get forwarded to diagnostics by internal/checker.
	testenv.NeedsGoPackages(t)

	files := map[string]string{
		"p/test.go": `package p // want "package name is p"`,
	}
	pkgname := &analysis.Analyzer{
		Name: "pkgname",
		Doc:  "trivial analyzer that reports package names",
		URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/internal/checker",
		Run: func(p *analysis.Pass) (any, error) {
			for _, f := range p.Files {
				p.ReportRangef(f.Name, "package name is %s", f.Name.Name)
			}
			return nil, nil
		},
	}

	testdata, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()
	path := filepath.Join(testdata, "src/p/test.go")
	results := analysistest.Run(t, testdata, pkgname, "file="+path)

	var urls []string
	for _, r := range results {
		for _, d := range r.Diagnostics {
			urls = append(urls, d.URL)
		}
	}
	want := []string{"https://pkg.go.dev/golang.org/x/tools/go/analysis/internal/checker"}
	if !reflect.DeepEqual(urls, want) {
		t.Errorf("Expected Diagnostics.URLs %v. got %v", want, urls)
	}
}

// TestPassReadFile exercises the Pass.ReadFile function.
func TestPassReadFile(t *testing.T) {
	cwd, _ := os.Getwd()

	const src = `
-- go.mod --
module example.com

-- p/file.go --
package p

-- p/ignored.go --
//go:build darwin && mips64

package p

hello from ignored

-- p/other.s --
hello from other
`

	// Expand archive into tmp tree.
	fs, err := txtar.FS(txtar.Parse([]byte(src)))
	if err != nil {
		t.Fatal(err)
	}
	tmpdir := testfiles.CopyToTmp(t, fs)

	ran := false
	a := &analysis.Analyzer{
		Name:     "a",
		Requires: []*analysis.Analyzer{inspect.Analyzer},
		Doc:      "doc",
		Run: func(pass *analysis.Pass) (any, error) {
			if len(pass.OtherFiles)+len(pass.IgnoredFiles) == 0 {
				t.Errorf("OtherFiles and IgnoredFiles are empty")
				return nil, nil
			}

			for _, test := range []struct {
				filename string
				want     string // substring of file content or error message
			}{
				{
					pass.OtherFiles[0], // [other.s]
					"hello from other",
				},
				{
					pass.IgnoredFiles[0], // [ignored.go]
					"hello from ignored",
				},
				{
					"nonesuch",
					"nonesuch is not among OtherFiles, ", // etc
				},
				{
					filepath.Join(cwd, "checker_test.go"),
					"checker_test.go is not among OtherFiles, ", // etc
				},
			} {
				content, err := pass.ReadFile(test.filename)
				var got string
				if err != nil {
					got = err.Error()
				} else {
					got = string(content)
					if len(got) > 100 {
						got = got[:100] + "..."
					}
				}
				if !strings.Contains(got, test.want) {
					t.Errorf("Pass.ReadFile(%q) did not contain %q; got:\n%s",
						test.filename, test.want, got)
				}
			}
			ran = true
			return nil, nil
		},
	}

	analysistest.Run(t, tmpdir, a, "example.com/p")

	if !ran {
		t.Error("analyzer did not run")
	}

	// TODO(adonovan): test that fixes are applied to the
	// pass.ReadFile virtual file tree.
}


================================================
FILE: go/analysis/internal/checker/fix_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package checker_test

import (
	"bytes"
	"flag"
	"fmt"
	"go/ast"
	"go/token"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/checker"
	"golang.org/x/tools/go/analysis/multichecker"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestMain(m *testing.M) {
	// If the CHECKER_TEST_CHILD environment variable is set,
	// this process should behave like a multichecker.
	// Analyzers are selected by flags.
	if _, ok := os.LookupEnv("CHECKER_TEST_CHILD"); ok {
		multichecker.Main(
			markerAnalyzer,
			noendAnalyzer,
			renameAnalyzer,
			relatedAnalyzer,
		)
		panic("unreachable")
	}

	// ordinary test
	flag.Parse()
	os.Exit(m.Run())
}

const (
	exitCodeSuccess     = 0 // success (no diagnostics, or successful -fix)
	exitCodeFailed      = 1 // analysis failed to run
	exitCodeDiagnostics = 3 // diagnostics were reported (and no -fix)
)

// TestReportInvalidDiagnostic tests that a call to pass.Report with
// certain kind of invalid diagnostic (e.g. conflicting fixes)
// promptly results in a panic.
func TestReportInvalidDiagnostic(t *testing.T) {
	testenv.NeedsGoPackages(t)

	// Load the errors package.
	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
	initial, err := packages.Load(cfg, "errors")
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		name string
		want string
		diag func(pos token.Pos) analysis.Diagnostic
	}{
		// Diagnostic has two alternative fixes with the same Message.
		{
			"duplicate message",
			`analyzer "a" suggests two fixes with same Message \(fix\)`,
			func(pos token.Pos) analysis.Diagnostic {
				return analysis.Diagnostic{
					Pos:     pos,
					Message: "oops",
					SuggestedFixes: []analysis.SuggestedFix{
						{Message: "fix"},
						{Message: "fix"},
					},
				}
			},
		},
		// TextEdit has invalid Pos.
		{
			"bad Pos",
			`analyzer "a" suggests invalid fix .*: no token.File for TextEdit.Pos .0.`,
			func(pos token.Pos) analysis.Diagnostic {
				return analysis.Diagnostic{
					Pos:     pos,
					Message: "oops",
					SuggestedFixes: []analysis.SuggestedFix{
						{
							Message:   "fix",
							TextEdits: []analysis.TextEdit{{}},
						},
					},
				}
			},
		},
		// TextEdit has invalid End.
		{
			"End < Pos",
			`analyzer "a" suggests invalid fix .*: TextEdit.Pos .* > TextEdit.End .*`,
			func(pos token.Pos) analysis.Diagnostic {
				return analysis.Diagnostic{
					Pos:     pos,
					Message: "oops",
					SuggestedFixes: []analysis.SuggestedFix{
						{
							Message: "fix",
							TextEdits: []analysis.TextEdit{{
								Pos: pos + 2,
								End: pos,
							}},
						},
					},
				}
			},
		},
		// Two TextEdits overlap.
		{
			"overlapping edits",
			`analyzer "a" suggests invalid fix .*: overlapping edits to .*errors.go \(1:1-1:3 and 1:2-1:4\)`,
			func(pos token.Pos) analysis.Diagnostic {
				return analysis.Diagnostic{
					Pos:     pos,
					Message: "oops",
					SuggestedFixes: []analysis.SuggestedFix{
						{
							Message: "fix",
							TextEdits: []analysis.TextEdit{
								{Pos: pos, End: pos + 2},
								{Pos: pos + 1, End: pos + 3},
							},
						},
					},
				}
			},
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			reached := false
			a := &analysis.Analyzer{Name: "a", Doc: "doc", Run: func(pass *analysis.Pass) (any, error) {
				reached = true
				panics(t, test.want, func() {
					pos := pass.Files[0].FileStart
					pass.Report(test.diag(pos))
				})
				return nil, nil
			}}
			if _, err := checker.Analyze([]*analysis.Analyzer{a}, initial, &checker.Options{}); err != nil {
				t.Fatalf("Analyze failed: %v", err)
			}
			if !reached {
				t.Error("analyzer was never invoked")
			}
		})
	}
}

// TestScript runs script-driven tests in testdata/*.txt.
// Each file is a txtar archive, expanded to a temporary directory.
//
// The comment section of the archive is a script, with the following
// commands:
//
//	# comment
//		ignored
//	blank line
//		ignored
//	skip k=v...
//		Skip the test if any k=v string is a substring of the string
//		"GOOS=darwin GOARCH=arm64" appropriate to the current build.
//	checker args...
//		Run the checker command with the specified space-separated
//		arguments; this fork+execs the [TestMain] function above.
//		If the archive has a "stdout" section, its contents must
//		match the stdout output of the checker command.
//		Do NOT use this for testing -diff: tests should not
//		rely on the particulars of the diff algorithm.
//	exit int
//		Assert that previous checker command had this exit code.
//	stderr regexp
//		Assert that stderr output from previous checker run matches this pattern.
//
// The script must include at least one 'checker' command.
func TestScript(t *testing.T) {
	testenv.NeedsExec(t)
	testenv.NeedsGoPackages(t)

	txtfiles, err := filepath.Glob("testdata/*.txt")
	if err != nil {
		t.Fatal(err)
	}
	for _, txtfile := range txtfiles {
		t.Run(txtfile, func(t *testing.T) {
			t.Parallel()

			// Expand archive into tmp tree.
			ar, err := txtar.ParseFile(txtfile)
			if err != nil {
				t.Fatal(err)
			}
			fs, err := txtar.FS(ar)
			if err != nil {
				t.Fatal(err)
			}
			dir := testfiles.CopyToTmp(t, fs)

			// Parse txtar comment as a script.
			const noExitCode = -999
			var (
				// state variables operated on by script
				lastExitCode = noExitCode
				lastStderr   string
			)
			for i, line := range strings.Split(string(ar.Comment), "\n") {
				line = strings.TrimSpace(line)
				if line == "" || line[0] == '#' {
					continue // skip blanks and comments
				}

				command, rest, _ := strings.Cut(line, " ")
				prefix := fmt.Sprintf("%s:%d: %s", txtfile, i+1, command) // for error messages
				switch command {
				case "checker":
					cmd := exec.Command(os.Args[0], strings.Fields(rest)...)
					cmd.Dir = dir
					cmd.Stdout = new(strings.Builder)
					cmd.Stderr = new(strings.Builder)
					cmd.Env = append(os.Environ(), "CHECKER_TEST_CHILD=1", "GOPROXY=off")
					if err := cmd.Run(); err != nil {
						if err, ok := err.(*exec.ExitError); ok {
							lastExitCode = err.ExitCode()
							// fall through
						} else {
							t.Fatalf("%s: failed to execute checker: %v (%s)", prefix, err, cmd)
						}
					} else {
						lastExitCode = 0 // success
					}

					// Eliminate nondeterministic strings from the output.
					clean := func(x any) string {
						s := fmt.Sprint(x)
						pwd, _ := os.Getwd()
						if realDir, err := filepath.EvalSymlinks(dir); err == nil {
							// Work around checker's packages.Load failing to
							// set Config.Dir to dir, causing the filenames
							// of loaded packages not to be a subdir of dir.
							s = strings.ReplaceAll(s, realDir, dir)
						}
						s = strings.ReplaceAll(s, dir, string(os.PathSeparator)+"TMP")
						s = strings.ReplaceAll(s, pwd, string(os.PathSeparator)+"PWD")
						s = strings.ReplaceAll(s, cmd.Path, filepath.Base(cmd.Path))
						return s
					}

					lastStderr = clean(cmd.Stderr)
					stdout := clean(cmd.Stdout)

					// Detect bad markers out of band:
					// though they cause a non-zero exit,
					// that may be expected.
					if strings.Contains(lastStderr, badMarker) {
						t.Errorf("marker analyzer encountered errors; stderr=%s", lastStderr)
					}

					// debugging
					if false {
						t.Logf("%s: $ %s\nstdout:\n%s\nstderr:\n%s", prefix, clean(cmd), stdout, lastStderr)
					}

					// Keep error reporting logic below consistent with
					// applyDiffsAndCompare in ../../analysistest/analysistest.go!

					unified := func(xlabel, ylabel string, x, y []byte) string {
						x = append(slices.Clip(bytes.TrimSpace(x)), '\n')
						y = append(slices.Clip(bytes.TrimSpace(y)), '\n')
						return diff.Unified(xlabel, ylabel, string(x), string(y))
					}

					// Check stdout, if there's a section of that name.
					//
					// Do not use this for testing -diff! It exposes tests to the
					// internals of our (often suboptimal) diff algorithm.
					// Instead, use the want/ mechanism.
					if f := section(ar, "stdout"); f != nil {
						got, want := []byte(stdout), f.Data
						if diff := unified("got", "want", got, want); diff != "" {
							t.Errorf("%s: unexpected stdout: -- got --\n%s-- want --\n%s-- diff --\n%s",
								prefix,
								got, want, diff)
						}
					}

					for _, f := range ar.Files {
						// For each file named want/X, assert that the
						// current content of X now equals want/X.
						if filename, ok := strings.CutPrefix(f.Name, "want/"); ok {
							fixed, err := os.ReadFile(filepath.Join(dir, filename))
							if err != nil {
								t.Errorf("reading %s: %v", filename, err)
								continue
							}
							var original []byte
							if f := section(ar, filename); f != nil {
								original = f.Data
							}
							want := f.Data
							if diff := unified(filename+" (fixed)", filename+" (want)", fixed, want); diff != "" {
								t.Errorf("%s: unexpected %s content:\n"+
									"-- original --\n%s\n"+
									"-- fixed --\n%s\n"+
									"-- want --\n%s\n"+
									"-- diff original fixed --\n%s\n"+
									"-- diff fixed want --\n%s",
									prefix, filename,
									original,
									fixed,
									want,
									unified(filename+" (original)", filename+" (fixed)", original, fixed),
									diff)
							}
						}
					}

				case "skip":
					config := fmt.Sprintf("GOOS=%s GOARCH=%s", runtime.GOOS, runtime.GOARCH)
					for word := range strings.FieldsSeq(rest) {
						if strings.Contains(config, word) {
							t.Skip(word)
						}
					}

				case "exit":
					if lastExitCode == noExitCode {
						t.Fatalf("%s: no prior 'checker' command", prefix)
					}
					var want int
					if _, err := fmt.Sscanf(rest, "%d", &want); err != nil {
						t.Fatalf("%s: requires one numeric operand", prefix)
					}
					if want != lastExitCode {
						// plan9 ExitCode() currently only returns 0 for success or 1 for failure
						if !(runtime.GOOS == "plan9" && want != exitCodeSuccess && lastExitCode != exitCodeSuccess) {
							t.Errorf("%s: exit code was %d, want %d", prefix, lastExitCode, want)
						}
					}

				case "stderr":
					if lastExitCode == noExitCode {
						t.Fatalf("%s: no prior 'checker' command", prefix)
					}
					if matched, err := regexp.MatchString(rest, lastStderr); err != nil {
						t.Fatalf("%s: invalid regexp: %v", prefix, err)
					} else if !matched {
						t.Errorf("%s: output didn't match pattern %q:\n%s", prefix, rest, lastStderr)
					}

				default:
					t.Errorf("%s: unknown command", prefix)
				}
			}
			if lastExitCode == noExitCode {
				t.Errorf("test script contains no 'checker' command")
			}
		})
	}
}

const badMarker = "[bad marker]"

// The marker analyzer generates fixes from @marker annotations in the
// source. Each marker is of the form:
//
//	@message("pattern", "replacement)
//
// The "message" is used for both the Diagnostic.Message and
// SuggestedFix.Message field. Multiple markers with the same
// message form a single diagnostic and fix with a list of textedits.
//
// The "pattern" is a regular expression that must match on the
// current line (though it may extend beyond if the pattern starts
// with "(?s)"), and whose extent forms the TextEdit.{Pos,End}
// deletion. If the pattern contains one subgroup, its range will be
// used; this allows contextual matching.
//
// The "replacement" is a literal string that forms the
// TextEdit.NewText.
//
// Fixes are applied in the order they are first mentioned in the
// source.
var markerAnalyzer = &analysis.Analyzer{
	Name:     "marker",
	Doc:      "doc",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run: func(pass *analysis.Pass) (_ any, err error) {
		// Errors returned by this analyzer cause the
		// checker command to exit non-zero, but that
		// may be the expected outcome for other reasons
		// (e.g. there were diagnostics).
		//
		// So, we report these errors out of band by logging
		// them with a special badMarker string that the
		// TestScript harness looks for, to ensure that the
		// test fails in that case.
		defer func() {
			if err != nil {
				log.Printf("%s: %v", badMarker, err)
			}
		}()

		// Parse all notes in the files.
		var keys []string
		edits := make(map[string][]analysis.TextEdit)
		for _, file := range pass.Files {
			tokFile := pass.Fset.File(file.FileStart)
			content, err := pass.ReadFile(tokFile.Name())
			if err != nil {
				return nil, err
			}
			notes, err := expect.ExtractGo(tokFile, file)
			if err != nil {
				return nil, err
			}
			for _, note := range notes {
				edit, err := markerEdit(tokFile, content, note)
				if err != nil {
					return nil, fmt.Errorf("%s: %v", tokFile.Position(note.Pos), err)
				}
				// Preserve note order as it determines fix order.
				if edits[note.Name] == nil {
					keys = append(keys, note.Name)
				}
				edits[note.Name] = append(edits[note.Name], edit)
			}
		}

		// Report each fix in its own Diagnostic.
		for _, key := range keys {
			edits := edits[key]
			// debugging
			if false {
				log.Printf("%s: marker: @%s: %+v", pass.Fset.Position(edits[0].Pos), key, edits)
			}
			pass.Report(analysis.Diagnostic{
				Pos:     edits[0].Pos,
				End:     edits[0].Pos,
				Message: key,
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   key,
					TextEdits: edits,
				}},
			})
		}
		return nil, nil
	},
}

// markerEdit returns the TextEdit denoted by note.
func markerEdit(tokFile *token.File, content []byte, note *expect.Note) (analysis.TextEdit, error) {
	if len(note.Args) != 2 {
		return analysis.TextEdit{}, fmt.Errorf("got %d args, want @%s(pattern, replacement)", len(note.Args), note.Name)
	}

	pattern, ok := note.Args[0].(string)
	if !ok {
		return analysis.TextEdit{}, fmt.Errorf("got %T for pattern, want string", note.Args[0])
	}
	rx, err := regexp.Compile(pattern)
	if err != nil {
		return analysis.TextEdit{}, fmt.Errorf("invalid pattern regexp: %v", err)
	}

	// Match the pattern against the current line.
	lineStart := tokFile.LineStart(tokFile.Position(note.Pos).Line)
	lineStartOff := tokFile.Offset(lineStart)
	lineEndOff := tokFile.Offset(note.Pos)
	matches := rx.FindSubmatchIndex(content[lineStartOff:])
	if len(matches) == 0 {
		return analysis.TextEdit{}, fmt.Errorf("no match for regexp %q", rx)
	}
	var start, end int // line-relative offset
	switch len(matches) {
	case 2:
		// no subgroups: return the range of the regexp expression
		start, end = matches[0], matches[1]
	case 4:
		// one subgroup: return its range
		start, end = matches[2], matches[3]
	default:
		return analysis.TextEdit{}, fmt.Errorf("invalid location regexp %q: expect either 0 or 1 subgroups, got %d", rx, len(matches)/2-1)
	}
	if start > lineEndOff-lineStartOff {
		// The start of the match must be between the start of the line and the
		// marker position (inclusive).
		return analysis.TextEdit{}, fmt.Errorf("no matching range found starting on the current line")
	}

	replacement, ok := note.Args[1].(string)
	if !ok {
		return analysis.TextEdit{}, fmt.Errorf("second argument must be pattern, got %T", note.Args[1])
	}

	// debugging: show matched portion
	if false {
		log.Printf("%s: %s: r%q (%q) -> %q",
			tokFile.Position(note.Pos),
			note.Name,
			pattern,
			content[lineStartOff+start:lineStartOff+end],
			replacement)
	}

	return analysis.TextEdit{
		Pos:     lineStart + token.Pos(start),
		End:     lineStart + token.Pos(end),
		NewText: []byte(replacement),
	}, nil
}

var renameAnalyzer = &analysis.Analyzer{
	Name:             "rename",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Doc:              "renames symbols named bar to baz",
	RunDespiteErrors: true,
	Run: func(pass *analysis.Pass) (any, error) {
		const (
			from = "bar"
			to   = "baz"
		)
		inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		nodeFilter := []ast.Node{(*ast.Ident)(nil)}
		inspect.Preorder(nodeFilter, func(n ast.Node) {
			ident := n.(*ast.Ident)
			if ident.Name == from {
				msg := fmt.Sprintf("renaming %q to %q", from, to)
				pass.Report(analysis.Diagnostic{
					Pos:     ident.Pos(),
					End:     ident.End(),
					Message: msg,
					SuggestedFixes: []analysis.SuggestedFix{{
						Message: msg,
						TextEdits: []analysis.TextEdit{{
							Pos:     ident.Pos(),
							End:     ident.End(),
							NewText: []byte(to),
						}},
					}},
				})
			}
		})
		return nil, nil
	},
}

var noendAnalyzer = &analysis.Analyzer{
	Name: "noend",
	Doc:  "inserts /*hello*/ before first decl",
	Run: func(pass *analysis.Pass) (any, error) {
		decl := pass.Files[0].Decls[0]
		pass.Report(analysis.Diagnostic{
			Pos:     decl.Pos(),
			End:     token.NoPos,
			Message: "say hello",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "say hello",
				TextEdits: []analysis.TextEdit{{
					Pos:     decl.Pos(),
					End:     token.NoPos,
					NewText: []byte("/*hello*/"),
				}},
			}},
		})
		return nil, nil
	},
}

var relatedAnalyzer = &analysis.Analyzer{
	Name: "related",
	Doc:  "reports a Diagnostic with RelatedInformaiton",
	Run: func(pass *analysis.Pass) (any, error) {
		decl := pass.Files[0].Decls[0]
		pass.Report(analysis.Diagnostic{
			Pos:     decl.Pos(),
			End:     decl.Pos() + 1,
			Message: "decl starts here",
			Related: []analysis.RelatedInformation{{
				Message: "decl ends here",
				Pos:     decl.End() - 1,
				End:     decl.End(),
			}},
		})
		return nil, nil
	},
}

// panics asserts that f() panics with with a value whose printed form matches the regexp want.
func panics(t *testing.T, want string, f func()) {
	defer func() {
		if x := recover(); x == nil {
			t.Errorf("function returned normally, wanted panic")
		} else if m, err := regexp.MatchString(want, fmt.Sprint(x)); err != nil {
			t.Errorf("panics: invalid regexp %q", want)
		} else if !m {
			t.Errorf("function panicked with value %q, want match for %q", x, want)
		}
	}()
	f()
}

// section returns the named archive section, or nil.
func section(ar *txtar.Archive, name string) *txtar.File {
	for i, f := range ar.Files {
		if f.Name == name {
			return &ar.Files[i]
		}
	}
	return nil
}


================================================
FILE: go/analysis/internal/checker/start_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package checker_test

import (
	"go/ast"
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/go/analysis/internal/checker"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/testenv"
)

// TestStartFixes make sure modifying the first character
// of the file takes effect.
func TestStartFixes(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.RedirectStderr(t) // associated checker.Run output with this test

	files := map[string]string{
		"comment/doc.go": `/* Package comment */
package comment
`}

	want := `// Package comment
package comment
`

	testdata, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	path := filepath.Join(testdata, "src/comment/doc.go")
	analysisflags.Fix = true
	checker.Run([]string{"file=" + path}, []*analysis.Analyzer{commentAnalyzer})
	analysisflags.Fix = false

	contents, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}

	got := string(contents)
	if got != want {
		t.Errorf("contents of rewritten file\ngot: %s\nwant: %s", got, want)
	}

	defer cleanup()
}

var commentAnalyzer = &analysis.Analyzer{
	Name:     "comment",
	Doc:      "comment",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      commentRun,
}

func commentRun(pass *analysis.Pass) (any, error) {
	const (
		from = "/* Package comment */"
		to   = "// Package comment"
	)
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	inspect.Preorder(nil, func(n ast.Node) {
		if n, ok := n.(*ast.Comment); ok && n.Text == from {
			pass.Report(analysis.Diagnostic{
				Pos: n.Pos(),
				End: n.End(),
				SuggestedFixes: []analysis.SuggestedFix{{
					TextEdits: []analysis.TextEdit{{
						Pos:     n.Pos(),
						End:     n.End(),
						NewText: []byte(to),
					}},
				}},
			})
		}
	})

	return nil, nil
}


================================================
FILE: go/analysis/internal/checker/testdata/conflict.txt
================================================
# Conflicting edits are legal, so long as they appear in different fixes.
# The driver will apply them in some order, and discard those that conflict.
#
# fix1 appears first, so is applied first; it succeeds.
# fix2 and fix3 conflict with it and are rejected.

checker -marker -fix example.com/a
exit 1
stderr applied 1 of 3 fixes; 1 file updated...Re-run

-- go.mod --
module example.com

go 1.22

-- a/a.go --
package a

func f() {
	bar := 12 //@ fix1("\tbar", "baz"), fix2("ar ", "baz"), fix3("bar", "lorem ipsum")
	_ = bar   //@ fix1(" bar", "baz")
}

-- want/a/a.go --
package a

func f() {
	baz := 12 //@ fix1("\tbar", "baz"), fix2("ar ", "baz"), fix3("bar", "lorem ipsum")
	_ = baz   //@ fix1(" bar", "baz")
}


================================================
FILE: go/analysis/internal/checker/testdata/diff.txt
================================================
# Basic test of -diff: ensure that stdout contains a diff,
# and the file system is unchanged.
#
# (Most tests of fixes should use want/* not -diff + stdout
# to avoid dependency on the diff algorithm.)
#
# File slashes assume non-Windows.

skip GOOS=windows
checker -rename -fix -diff example.com/p
exit 0

-- go.mod --
module example.com
go 1.22

-- p/p.go --
package p

var bar int

-- want/p/p.go --
package p

var bar int

-- stdout --
--- /TMP/p/p.go (old)
+++ /TMP/p/p.go (new)
@@ -1,4 +1,3 @@
 package p
 
-var bar int
-
+var baz int


================================================
FILE: go/analysis/internal/checker/testdata/fixes.txt
================================================
# Ensure that fixes are applied correctly, in
# particular when processing duplicate fixes for overlapping packages
# in the same directory ("p", "p [p.test]", "p_test [p.test]").

checker -rename -fix -v example.com/p
stderr applied 8 fixes, updated 3 files
exit 0

-- go.mod --
module example.com
go 1.22

-- p/p.go --
package p

func Foo() {
	bar := 12
	_ = bar
}

-- p/p_test.go --
package p

func InTestFile() {
	bar := 13
	_ = bar
}

-- p/p_x_test.go --
package p_test

func Foo() {
	bar := 14
	_ = bar
}

-- want/p/p.go --
package p

func Foo() {
	baz := 12
	_ = baz
}

-- want/p/p_test.go --
package p

func InTestFile() {
	baz := 13
	_ = baz
}

-- want/p/p_x_test.go --
package p_test

func Foo() {
	baz := 14
	_ = baz
}


================================================
FILE: go/analysis/internal/checker/testdata/generated.txt
================================================
# This test exercises skipping of fixes that edit generated
# files, and the summary logging thereof.

checker -rename -marker -fix -v example.com/a
stderr skipped 1 fix that would edit generated files
stderr applied 2 fixes, updated 1 file
exit 0

-- go.mod --
module example.com
go 1.22

-- a/a.go --
package a

var A int //@ fix("A", "A2")

-- a/gena.go --
// Code generated by hand. DO NOT EDIT.

package a

var B int //@ fix2("B", "B2")

-- want/a/a.go --
package a

var A2 int //@ fix("A", "A2")

-- want/a/gena.go --
// Code generated by hand. DO NOT EDIT.

package a

var B int //@ fix2("B", "B2")


================================================
FILE: go/analysis/internal/checker/testdata/importdup.txt
================================================
# Test that duplicate imports--and, more generally, duplicate
# identical insertions--are coalesced.

checker -marker -fix -v example.com/a
stderr applied 2 fixes, updated 1 file
exit 0

-- go.mod --
module example.com
go 1.22

-- a/a.go --
package a

import (
	_ "errors"
	//@ fix1("()//", `"foo"`), fix2("()//", `"foo"`)
)

func f() {} //@ fix1("()}", "n++"), fix2("()}", "n++")

-- want/a/a.go --
package a

import (
	_ "errors"
	"foo" //@ fix1("()//", `"foo"`), fix2("()//", `"foo"`)
)

func f() { n++ } //@ fix1("()}", "n++"), fix2("()}", "n++")


================================================
FILE: go/analysis/internal/checker/testdata/importdup2.txt
================================================
# Test of import de-duplication behavior.
#
# In packages a and b, there are three fixes,
# each adding one of two imports, but in different order.
#
# In package a, the fixes are [foo, foo, bar],
# and they are resolved as follows:
# - foo is applied    -> [foo]
# - foo is coalesced  -> [foo]
# - bar is applied    -> [foo bar]
# The result is then formatted to [bar foo].
#
# In package b, the fixes are [foo, bar, foo]:
# - foo is applied   -> [foo]
# - bar is applied   -> [foo bar]
# - foo is coalesced -> [foo bar]
# The same result is again formatted to [bar foo].
#
# In more complex examples, the result
# may be more subtly order-dependent.

checker -marker -fix -v example.com/a example.com/b
stderr applied 6 fixes, updated 2 files
exit 0

-- go.mod --
module example.com
go 1.22

-- a/a.go --
package a

import (
	//@ fix1("()//", "\"foo\"\n"), fix2("()//", "\"foo\"\n"), fix3("()//", "\"bar\"\n")
)

-- want/a/a.go --
package a

import (
	"bar"
	"foo"
	// @ fix1("()//", "\"foo\"\n"), fix2("()//", "\"foo\"\n"), fix3("()//", "\"bar\"\n")
)

-- b/b.go --
package b

import (
	//@ fix1("()//", "\"foo\"\n"), fix2("()//", "\"bar\"\n"), fix3("()//", "\"foo\"\n")
)

-- want/b/b.go --
package b

import (
	"bar"
	"foo"
	// @ fix1("()//", "\"foo\"\n"), fix2("()//", "\"bar\"\n"), fix3("()//", "\"foo\"\n")
)



================================================
FILE: go/analysis/internal/checker/testdata/json.txt
================================================
# Test basic JSON output.

# File slashes assume non-Windows.
skip GOOS=windows

checker -rename -json example.com/p
exit 0

-- go.mod --
module example.com
go 1.22

-- p/p.go --
package p

func f(bar int) {}

-- stdout --
{
	"example.com/p": {
		"rename": [
			{
				"posn": "/TMP/p/p.go:3:8",
				"end": "/TMP/p/p.go:3:11",
				"message": "renaming \"bar\" to \"baz\"",
				"suggested_fixes": [
					{
						"message": "renaming \"bar\" to \"baz\"",
						"edits": [
							{
								"filename": "/TMP/p/p.go",
								"start": 18,
								"end": 21,
								"new": "baz"
							}
						]
					}
				]
			}
		]
	}
}



================================================
FILE: go/analysis/internal/checker/testdata/noend.txt
================================================
# Test that a missing SuggestedFix.End position is correctly
# interpreted as if equal to SuggestedFix.Pos (see issue #64199).

checker -noend -fix example.com/a
exit 0

-- go.mod --
module example.com
go 1.22

-- a/a.go --
package a

func f() {}

-- want/a/a.go --
package a

/*hello*/
func f() {}


================================================
FILE: go/analysis/internal/checker/testdata/overlap.txt
================================================
# This test exercises an edge case of merging.
#
# Two analyzers generate overlapping fixes for this package:
# - 'rename' changes "bar" to "baz"
# - 'marker' changes  "ar" to "baz"
# Historically this used to cause a conflict, but as it happens,
# the new merge algorithm splits the rename fix, since it overlaps
# the marker fix, into two subedits:
# - a deletion of "b" and
# - an edit from "ar" to "baz".
# The deletion is of course nonoverlapping, and the edit,
# by happy chance, is identical to the marker fix, so the two
# are coalesced.
#
# (This is a pretty unlikely situation, but it corresponds
# to a historical test, TestOther, that used to check for
# a conflict, and it seemed wrong to delete it without explanation.)
#
# The fixes are silently and successfully applied.

checker -rename -marker -fix -v example.com/a
stderr applied 2 fixes, updated 1 file
exit 0

-- go.mod --
module example.com
go 1.22

-- a/a.go --
package a

func f(bar int) {} //@ fix("ar", "baz")

-- want/a/a.go --
package a

func f(baz int) {} //@ fix("ar", "baz")


================================================
FILE: go/analysis/internal/checker/testdata/plain.txt
================================================
# Test plain output.
#
# File slashes assume non-Windows.
skip GOOS=windows

checker -related example.com/p
stderr p/p.go:3:1: decl starts here
stderr p/p.go:4:1: 	decl ends here

checker -related -c=0 example.com/p
stderr p/p.go:3:1: decl starts here
stderr 3	func f\(bar int\) {
stderr p/p.go:4:1: 	decl ends here
stderr 4	}
exit 3

-- go.mod --
module example.com
go 1.22

-- p/p.go --
package p

func f(bar int) {
}


================================================
FILE: go/analysis/internal/internal.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package internal

import "golang.org/x/tools/go/analysis"

// This function is set by the checker package to provide
// backdoor access to the private Pass field
// of the *checker.Action type, for use by analysistest.
//
// It may return nil, for example if the action was not
// executed because of a failed dependent.
var ActionPass func(action any) *analysis.Pass


================================================
FILE: go/analysis/internal/versiontest/version_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.21

// Check that GoVersion propagates through to checkers.
// Depends on Go 1.21 go/types.

package versiontest

import (
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/multichecker"
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/internal/testenv"
)

var analyzer = &analysis.Analyzer{
	Name: "versiontest",
	Doc:  "off",
	Run: func(pass *analysis.Pass) (any, error) {
		pass.Reportf(pass.Files[0].Package, "goversion=%s", pass.Pkg.GoVersion())
		return nil, nil
	},
}

func init() {
	if os.Getenv("VERSIONTEST_MULTICHECKER") == "1" {
		multichecker.Main(analyzer)
		os.Exit(0)
	}
	if os.Getenv("VERSIONTEST_SINGLECHECKER") == "1" {
		singlechecker.Main(analyzer)
		os.Exit(0)
	}
}

func testDir(t *testing.T) (dir string) {
	dir = t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("go 1.20\nmodule m\n"), 0666); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "x.go"), []byte("package main // want \"goversion=go1.20\"\n"), 0666); err != nil {
		t.Fatal(err)
	}
	return dir
}

// There are many ways to run analyzers. Test all the ones here in x/tools.

func TestAnalysistest(t *testing.T) {
	analysistest.Run(t, testDir(t), analyzer)
}

func TestMultichecker(t *testing.T) {
	testenv.NeedsGoPackages(t)

	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command(exe, ".")
	cmd.Dir = testDir(t)
	cmd.Env = append(os.Environ(), "VERSIONTEST_MULTICHECKER=1")
	out, err := cmd.CombinedOutput()
	if err == nil || !strings.Contains(string(out), "x.go:1:1: goversion=go1.20") {
		t.Fatalf("multichecker: %v\n%s", err, out)
	}
}

func TestSinglechecker(t *testing.T) {
	testenv.NeedsGoPackages(t)

	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command(exe, ".")
	cmd.Dir = testDir(t)
	cmd.Env = append(os.Environ(), "VERSIONTEST_SINGLECHECKER=1")
	out, err := cmd.CombinedOutput()
	if err == nil || !strings.Contains(string(out), "x.go:1:1: goversion=go1.20") {
		t.Fatalf("multichecker: %v\n%s", err, out)
	}
}

func TestVettool(t *testing.T) {
	testenv.NeedsGoPackages(t)

	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command("go", "vet", "-vettool="+exe, ".")
	cmd.Dir = testDir(t)
	cmd.Env = append(os.Environ(), "VERSIONTEST_MULTICHECKER=1")
	out, err := cmd.CombinedOutput()
	if err == nil || !strings.Contains(string(out), "x.go:1:1: goversion=go1.20") {
		t.Fatalf("vettool: %v\n%s", err, out)
	}
}


================================================
FILE: go/analysis/multichecker/multichecker.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package multichecker defines the main function for an analysis driver
// with several analyzers. This package makes it easy for anyone to build
// an analysis tool containing just the analyzers they need.
package multichecker

import (
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/go/analysis/internal/checker"
	"golang.org/x/tools/go/analysis/unitchecker"
)

func Main(analyzers ...*analysis.Analyzer) {
	progname := filepath.Base(os.Args[0])
	log.SetFlags(0)
	log.SetPrefix(progname + ": ") // e.g. "vet: "

	if err := analysis.Validate(analyzers); err != nil {
		log.Fatal(err)
	}

	checker.RegisterFlags()

	analyzers = analysisflags.Parse(analyzers, true)

	args := flag.Args()
	if len(args) == 0 {
		fmt.Fprintf(os.Stderr, `%[1]s is a tool for static analysis of Go programs.

Usage: %[1]s [-flag] [package]

Run '%[1]s help' for more detail,
 or '%[1]s help name' for details and flags of a specific analyzer.
`, progname)
		os.Exit(1)
	}

	if args[0] == "help" {
		analysisflags.Help(progname, analyzers, args[1:])
		os.Exit(0)
	}

	if len(args) == 1 && strings.HasSuffix(args[0], ".cfg") {
		unitchecker.Run(args[0], analyzers)
		panic("unreachable")
	}

	os.Exit(checker.Run(args, analyzers))
}


================================================
FILE: go/analysis/multichecker/multichecker_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.12

package multichecker_test

import (
	"fmt"
	"os"
	"os/exec"
	"runtime"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/multichecker"
	"golang.org/x/tools/go/analysis/passes/findcall"
	"golang.org/x/tools/internal/testenv"
)

func main() {
	fail := &analysis.Analyzer{
		Name: "fail",
		Doc:  "always fail on a package 'sort'",
		Run: func(pass *analysis.Pass) (any, error) {
			if pass.Pkg.Path() == "sort" {
				return nil, fmt.Errorf("failed")
			}
			return nil, nil
		},
	}
	multichecker.Main(findcall.Analyzer, fail)
}

// TestExitCode ensures that analysis failures are reported correctly.
// This test fork/execs the main function above.
func TestExitCode(t *testing.T) {
	if runtime.GOOS != "linux" {
		t.Skipf("skipping fork/exec test on this platform")
	}

	if os.Getenv("MULTICHECKER_CHILD") == "1" {
		// child process

		// replace [progname -test.run=TestExitCode -- ...]
		//      by [progname ...]
		os.Args = os.Args[2:]
		os.Args[0] = "vet"
		main()
		panic("unreachable")
	}

	testenv.NeedsTool(t, "go")

	for _, test := range []struct {
		args []string
		want int
	}{
		{[]string{"nosuchdir/..."}, 1},                      // matched no packages
		{[]string{"nosuchpkg"}, 1},                          // matched no packages
		{[]string{"-unknownflag"}, 2},                       // flag error
		{[]string{"-findcall.name=panic", "io"}, 3},         // finds diagnostics
		{[]string{"-findcall=0", "io"}, 0},                  // no checkers
		{[]string{"-findcall.name=nosuchfunc", "io"}, 0},    // no diagnostics
		{[]string{"-findcall.name=panic", "sort", "io"}, 1}, // 'fail' failed on 'sort'

		// -json: exits zero even in face of diagnostics or package errors.
		{[]string{"-findcall.name=panic", "-json", "io"}, 0},
		{[]string{"-findcall.name=panic", "-json", "io"}, 0},
		{[]string{"-findcall.name=panic", "-json", "sort", "io"}, 0},
	} {
		args := []string{"-test.run=TestExitCode", "--"}
		args = append(args, test.args...)
		cmd := exec.Command(os.Args[0], args...)
		cmd.Env = append(os.Environ(), "MULTICHECKER_CHILD=1")
		out, err := cmd.CombinedOutput()
		if len(out) > 0 {
			t.Logf("%s: out=<<%s>>", test.args, out)
		}
		var exitcode int
		if err, ok := err.(*exec.ExitError); ok {
			exitcode = err.ExitCode() // requires go1.12
		}
		if exitcode != test.want {
			t.Errorf("%s: exited %d, want %d", test.args, exitcode, test.want)
		}
	}
}


================================================
FILE: go/analysis/passes/README
================================================

This directory does not contain a Go package,
but acts as a container for various analyses
that implement the golang.org/x/tools/go/analysis
API and may be imported into an analysis tool.

By convention, each package foo provides the analysis,
and each command foo/cmd/foo provides a standalone driver.


================================================
FILE: go/analysis/passes/appends/appends.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package appends defines an Analyzer that detects
// if there is only one variable in append.
package appends

import (
	_ "embed"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "appends",
	Doc:      analyzerutil.MustExtractDoc(doc, "appends"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/appends",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		b, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Builtin)
		if ok && b.Name() == "append" && len(call.Args) == 1 {
			pass.ReportRangef(call, "append with no values")
		}
	})

	return nil, nil
}


================================================
FILE: go/analysis/passes/appends/appends_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package appends_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/appends"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	tests := []string{"a", "b"}
	analysistest.Run(t, testdata, appends.Analyzer, tests...)
}


================================================
FILE: go/analysis/passes/appends/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package appends defines an Analyzer that detects
// if there is only one variable in append.
//
// # Analyzer appends
//
// appends: check for missing values after append
//
// This checker reports calls to append that pass
// no values to be appended to the slice.
//
//	s := []string{"a", "b", "c"}
//	_ = append(s)
//
// Such calls are always no-ops and often indicate an
// underlying mistake.
package appends


================================================
FILE: go/analysis/passes/appends/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the appends checker.

package a

func badAppendSlice1() {
	sli := []string{"a", "b", "c"}
	sli = append(sli) // want "append with no values"
}

func badAppendSlice2() {
	_ = append([]string{"a"}) // want "append with no values"
}

func goodAppendSlice1() {
	sli := []string{"a", "b", "c"}
	sli = append(sli, "d")
}

func goodAppendSlice2() {
	sli1 := []string{"a", "b", "c"}
	sli2 := []string{"d", "e", "f"}
	sli1 = append(sli1, sli2...)
}

func goodAppendSlice3() {
	sli := []string{"a", "b", "c"}
	sli = append(sli, "d", "e", "f")
}


================================================
FILE: go/analysis/passes/appends/testdata/src/b/b.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the appends checker.

package b

func append(args ...interface{}) []int {
	println(args)
	return []int{0}
}

func userdefine() {
	sli := []int{1, 2, 3}
	sli = append(sli, 4, 5, 6)
	sli = append(sli)
}

func localvar() {
	append := func(int) int { return 0 }
	a := append(1)
	_ = a
}


================================================
FILE: go/analysis/passes/asmdecl/asmdecl.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package asmdecl defines an Analyzer that reports mismatches between
// assembly files and Go declarations.
package asmdecl

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/token"
	"go/types"
	"log"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

const Doc = "report mismatches between assembly files and Go declarations"

var Analyzer = &analysis.Analyzer{
	Name: "asmdecl",
	Doc:  Doc,
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/asmdecl",
	Run:  run,
}

// 'kind' is a kind of assembly variable.
// The kinds 1, 2, 4, 8 stand for values of that size.
type asmKind int

// These special kinds are not valid sizes.
const (
	asmString asmKind = 100 + iota
	asmSlice
	asmArray
	asmInterface
	asmEmptyInterface
	asmStruct
	asmComplex
)

// An asmArch describes assembly parameters for an architecture
type asmArch struct {
	name      string
	bigEndian bool
	stack     string
	lr        bool
	// retRegs is a list of registers for return value in register ABI (ABIInternal).
	// For now, as we only check whether we write to any result, here we only need to
	// include the first integer register and first floating-point register. Accessing
	// any of them counts as writing to result.
	retRegs []string
	// writeResult is a list of instructions that will change result register implicitly.
	writeResult []string
	// calculated during initialization
	sizes    types.Sizes
	intSize  int
	ptrSize  int
	maxAlign int
}

// An asmFunc describes the expected variables for a function on a given architecture.
type asmFunc struct {
	arch        *asmArch
	size        int // size of all arguments
	vars        map[string]*asmVar
	varByOffset map[int]*asmVar
}

// An asmVar describes a single assembly variable.
type asmVar struct {
	name  string
	kind  asmKind
	typ   string
	off   int
	size  int
	inner []*asmVar
}

var (
	asmArch386      = asmArch{name: "386", bigEndian: false, stack: "SP", lr: false}
	asmArchArm      = asmArch{name: "arm", bigEndian: false, stack: "R13", lr: true}
	asmArchArm64    = asmArch{name: "arm64", bigEndian: false, stack: "RSP", lr: true, retRegs: []string{"R0", "F0"}, writeResult: []string{"SVC"}}
	asmArchAmd64    = asmArch{name: "amd64", bigEndian: false, stack: "SP", lr: false, retRegs: []string{"AX", "X0"}, writeResult: []string{"SYSCALL"}}
	asmArchMips     = asmArch{name: "mips", bigEndian: true, stack: "R29", lr: true}
	asmArchMipsLE   = asmArch{name: "mipsle", bigEndian: false, stack: "R29", lr: true}
	asmArchMips64   = asmArch{name: "mips64", bigEndian: true, stack: "R29", lr: true}
	asmArchMips64LE = asmArch{name: "mips64le", bigEndian: false, stack: "R29", lr: true}
	asmArchPpc64    = asmArch{name: "ppc64", bigEndian: true, stack: "R1", lr: true, retRegs: []string{"R3", "F1"}, writeResult: []string{"SYSCALL"}}
	asmArchPpc64LE  = asmArch{name: "ppc64le", bigEndian: false, stack: "R1", lr: true, retRegs: []string{"R3", "F1"}, writeResult: []string{"SYSCALL"}}
	asmArchRISCV64  = asmArch{name: "riscv64", bigEndian: false, stack: "SP", lr: true, retRegs: []string{"X10", "F10"}, writeResult: []string{"ECALL"}}
	asmArchS390X    = asmArch{name: "s390x", bigEndian: true, stack: "R15", lr: true}
	asmArchWasm     = asmArch{name: "wasm", bigEndian: false, stack: "SP", lr: false}
	asmArchLoong64  = asmArch{name: "loong64", bigEndian: false, stack: "R3", lr: true, retRegs: []string{"R4", "F0"}, writeResult: []string{"SYSCALL"}}

	arches = []*asmArch{
		&asmArch386,
		&asmArchArm,
		&asmArchArm64,
		&asmArchAmd64,
		&asmArchMips,
		&asmArchMipsLE,
		&asmArchMips64,
		&asmArchMips64LE,
		&asmArchPpc64,
		&asmArchPpc64LE,
		&asmArchRISCV64,
		&asmArchS390X,
		&asmArchWasm,
		&asmArchLoong64,
	}
)

func init() {
	for _, arch := range arches {
		arch.sizes = types.SizesFor("gc", arch.name)
		if arch.sizes == nil {
			// TODO(adonovan): fix: now that asmdecl is not in the standard
			// library we cannot assume types.SizesFor is consistent with arches.
			// For now, assume 64-bit norms and print a warning.
			// But this warning should really be deferred until we attempt to use
			// arch, which is very unlikely. Better would be
			// to defer size computation until we have Pass.TypesSizes.
			arch.sizes = types.SizesFor("gc", "amd64")
			log.Printf("unknown architecture %s", arch.name)
		}
		arch.intSize = int(arch.sizes.Sizeof(types.Typ[types.Int]))
		arch.ptrSize = int(arch.sizes.Sizeof(types.Typ[types.UnsafePointer]))
		arch.maxAlign = int(arch.sizes.Alignof(types.Typ[types.Int64]))
	}
}

var (
	re           = regexp.MustCompile
	asmPlusBuild = re(`//\s+\+build\s+([^\n]+)`)
	asmTEXT      = re(`\bTEXT\b(.*)·([^\(]+)\(SB\)(?:\s*,\s*([0-9A-Z|+()]+))?(?:\s*,\s*\$(-?[0-9]+)(?:-([0-9]+))?)?`)
	asmDATA      = re(`\b(DATA|GLOBL)\b`)
	asmNamedFP   = re(`\$?([a-zA-Z0-9_\xFF-\x{10FFFF}]+)(?:\+([0-9]+))\(FP\)`)
	asmUnnamedFP = re(`[^+\-0-9](([0-9]+)\(FP\))`)
	asmSP        = re(`[^+\-0-9](([0-9]+)\(([A-Z0-9]+)\))`)
	asmOpcode    = re(`^\s*(?:[A-Z0-9a-z_]+:)?\s*([A-Z]+)\s*([^,]*)(?:,\s*(.*))?`)
	ppc64Suff    = re(`([BHWD])(ZU|Z|U|BR)?$`)
	abiSuff      = re(`^(.+)<(ABI.+)>$`)
)

func run(pass *analysis.Pass) (any, error) {
	// No work if no assembly files.
	var sfiles []string
	for _, fname := range pass.OtherFiles {
		if strings.HasSuffix(fname, ".s") {
			sfiles = append(sfiles, fname)
		}
	}
	if sfiles == nil {
		return nil, nil
	}

	// Gather declarations. knownFunc[name][arch] is func description.
	knownFunc := make(map[string]map[string]*asmFunc)

	for _, f := range pass.Files {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok && decl.Body == nil {
				knownFunc[decl.Name.Name] = asmParseDecl(pass, decl)
			}
		}
	}

Files:
	for _, fname := range sfiles {
		content, tf, err := analyzerutil.ReadFile(pass, fname)
		if err != nil {
			return nil, err
		}

		// Determine architecture from file name if possible.
		var arch string
		var archDef *asmArch
		for _, a := range arches {
			if strings.HasSuffix(fname, "_"+a.name+".s") {
				arch = a.name
				archDef = a
				break
			}
		}

		lines := strings.SplitAfter(string(content), "\n")
		var (
			fn                 *asmFunc
			fnName             string
			abi                string
			localSize, argSize int
			wroteSP            bool
			noframe            bool
			haveRetArg         bool
			retLine            []int
		)

		flushRet := func() {
			if fn != nil && fn.vars["ret"] != nil && !haveRetArg && len(retLine) > 0 {
				v := fn.vars["ret"]
				resultStr := fmt.Sprintf("%d-byte ret+%d(FP)", v.size, v.off)
				if abi == "ABIInternal" {
					resultStr = "result register"
				}
				for _, line := range retLine {
					pass.Reportf(tf.LineStart(line), "[%s] %s: RET without writing to %s", arch, fnName, resultStr)
				}
			}
			retLine = nil
		}
		trimABI := func(fnName string) (string, string) {
			m := abiSuff.FindStringSubmatch(fnName)
			if m != nil {
				return m[1], m[2]
			}
			return fnName, ""
		}
		for lineno, line := range lines {
			lineno++

			badf := func(format string, args ...any) {
				pass.Reportf(tf.LineStart(lineno), "[%s] %s: %s", arch, fnName, fmt.Sprintf(format, args...))
			}

			if arch == "" {
				// Determine architecture from +build line if possible.
				if m := asmPlusBuild.FindStringSubmatch(line); m != nil {
					// There can be multiple architectures in a single +build line,
					// so accumulate them all and then prefer the one that
					// matches build.Default.GOARCH.
					var archCandidates []*asmArch
					for fld := range strings.FieldsSeq(m[1]) {
						for _, a := range arches {
							if a.name == fld {
								archCandidates = append(archCandidates, a)
							}
						}
					}
					for _, a := range archCandidates {
						if a.name == build.Default.GOARCH {
							archCandidates = []*asmArch{a}
							break
						}
					}
					if len(archCandidates) > 0 {
						arch = archCandidates[0].name
						archDef = archCandidates[0]
					}
				}
			}

			// Ignore comments and commented-out code.
			if i := strings.Index(line, "//"); i >= 0 {
				line = line[:i]
			}

			if m := asmTEXT.FindStringSubmatch(line); m != nil {
				flushRet()
				if arch == "" {
					// Arch not specified by filename or build tags.
					// Fall back to build.Default.GOARCH.
					for _, a := range arches {
						if a.name == build.Default.GOARCH {
							arch = a.name
							archDef = a
							break
						}
					}
					if arch == "" {
						log.Printf("%s: cannot determine architecture for assembly file", fname)
						continue Files
					}
				}
				fnName = m[2]
				if pkgPath := strings.TrimSpace(m[1]); pkgPath != "" {
					// The assembler uses Unicode division slash within
					// identifiers to represent the directory separator.
					pkgPath = strings.Replace(pkgPath, "∕", "/", -1)
					if pkgPath != pass.Pkg.Path() {
						// log.Printf("%s:%d: [%s] cannot check cross-package assembly function: %s is in package %s", fname, lineno, arch, fnName, pkgPath)
						fn = nil
						fnName = ""
						abi = ""
						continue
					}
				}
				// Trim off optional ABI selector.
				fnName, abi = trimABI(fnName)
				flag := m[3]
				fn = knownFunc[fnName][arch]
				if fn != nil {
					size, _ := strconv.Atoi(m[5])
					if size != fn.size && (flag != "7" && !strings.Contains(flag, "NOSPLIT") || size != 0) {
						badf("wrong argument size %d; expected $...-%d", size, fn.size)
					}
				}
				localSize, _ = strconv.Atoi(m[4])
				localSize += archDef.intSize
				if archDef.lr && !strings.Contains(flag, "NOFRAME") {
					// Account for caller's saved LR
					localSize += archDef.intSize
				}
				argSize, _ = strconv.Atoi(m[5])
				noframe = strings.Contains(flag, "NOFRAME")
				if fn == nil && !strings.Contains(fnName, "<>") && !noframe {
					badf("function %s missing Go declaration", fnName)
				}
				wroteSP = false
				haveRetArg = false
				continue
			} else if strings.Contains(line, "TEXT") && strings.Contains(line, "SB") {
				// function, but not visible from Go (didn't match asmTEXT), so stop checking
				flushRet()
				fn = nil
				fnName = ""
				abi = ""
				continue
			}

			if strings.Contains(line, "RET") && !strings.Contains(line, "(SB)") {
				// RET f(SB) is a tail call. It is okay to not write the results.
				retLine = append(retLine, lineno)
			}

			if fnName == "" {
				continue
			}

			if asmDATA.FindStringSubmatch(line) != nil {
				fn = nil
			}

			if archDef == nil {
				continue
			}

			if strings.Contains(line, ", "+archDef.stack) || strings.Contains(line, ",\t"+archDef.stack) || strings.Contains(line, "NOP "+archDef.stack) || strings.Contains(line, "NOP\t"+archDef.stack) {
				wroteSP = true
				continue
			}

			if arch == "wasm" && strings.Contains(line, "CallImport") {
				// CallImport is a call out to magic that can write the result.
				haveRetArg = true
			}

			if abi == "ABIInternal" && !haveRetArg {
				for _, ins := range archDef.writeResult {
					if strings.Contains(line, ins) {
						haveRetArg = true
						break
					}
				}
				for _, reg := range archDef.retRegs {
					if strings.Contains(line, reg) {
						haveRetArg = true
						break
					}
				}
			}

			for _, m := range asmSP.FindAllStringSubmatch(line, -1) {
				if m[3] != archDef.stack || wroteSP || noframe {
					continue
				}
				off := 0
				if m[1] != "" {
					off, _ = strconv.Atoi(m[2])
				}
				if off >= localSize {
					if fn != nil {
						v := fn.varByOffset[off-localSize]
						if v != nil {
							badf("%s should be %s+%d(FP)", m[1], v.name, off-localSize)
							continue
						}
					}
					if off >= localSize+argSize {
						badf("use of %s points beyond argument frame", m[1])
						continue
					}
					badf("use of %s to access argument frame", m[1])
				}
			}

			if fn == nil {
				continue
			}

			for _, m := range asmUnnamedFP.FindAllStringSubmatch(line, -1) {
				off, _ := strconv.Atoi(m[2])
				v := fn.varByOffset[off]
				if v != nil {
					badf("use of unnamed argument %s; offset %d is %s+%d(FP)", m[1], off, v.name, v.off)
				} else {
					badf("use of unnamed argument %s", m[1])
				}
			}

			for _, m := range asmNamedFP.FindAllStringSubmatch(line, -1) {
				name := m[1]
				off := 0
				if m[2] != "" {
					off, _ = strconv.Atoi(m[2])
				}
				if name == "ret" || strings.HasPrefix(name, "ret_") {
					haveRetArg = true
				}
				v := fn.vars[name]
				if v == nil {
					// Allow argframe+0(FP).
					if name == "argframe" && off == 0 {
						continue
					}
					v = fn.varByOffset[off]
					if v != nil {
						badf("unknown variable %s; offset %d is %s+%d(FP)", name, off, v.name, v.off)
					} else {
						badf("unknown variable %s", name)
					}
					continue
				}
				asmCheckVar(badf, fn, line, m[0], off, v, archDef)
			}
		}
		flushRet()
	}
	return nil, nil
}

func asmKindForType(t types.Type, size int) asmKind {
	switch t := t.Underlying().(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String:
			return asmString
		case types.Complex64, types.Complex128:
			return asmComplex
		}
		return asmKind(size)
	case *types.Pointer, *types.Chan, *types.Map, *types.Signature:
		return asmKind(size)
	case *types.Struct:
		return asmStruct
	case *types.Interface:
		if t.Empty() {
			return asmEmptyInterface
		}
		return asmInterface
	case *types.Array:
		return asmArray
	case *types.Slice:
		return asmSlice
	}
	panic("unreachable")
}

// A component is an assembly-addressable component of a composite type,
// or a composite type itself.
type component struct {
	size   int
	offset int
	kind   asmKind
	typ    string
	suffix string // Such as _base for string base, _0_lo for lo half of first element of [1]uint64 on 32 bit machine.
	outer  string // The suffix for immediately containing composite type.
}

func newComponent(suffix string, kind asmKind, typ string, offset, size int, outer string) component {
	return component{suffix: suffix, kind: kind, typ: typ, offset: offset, size: size, outer: outer}
}

// componentsOfType generates a list of components of type t.
// For example, given string, the components are the string itself, the base, and the length.
func componentsOfType(arch *asmArch, t types.Type) []component {
	return appendComponentsRecursive(arch, t, nil, "", 0)
}

// appendComponentsRecursive implements componentsOfType.
// Recursion is required to correct handle structs and arrays,
// which can contain arbitrary other types.
func appendComponentsRecursive(arch *asmArch, t types.Type, cc []component, suffix string, off int) []component {
	s := t.String()
	size := int(arch.sizes.Sizeof(t))
	kind := asmKindForType(t, size)
	cc = append(cc, newComponent(suffix, kind, s, off, size, suffix))

	switch kind {
	case 8:
		if arch.ptrSize == 4 {
			w1, w2 := "lo", "hi"
			if arch.bigEndian {
				w1, w2 = w2, w1
			}
			cc = append(cc, newComponent(suffix+"_"+w1, 4, "half "+s, off, 4, suffix))
			cc = append(cc, newComponent(suffix+"_"+w2, 4, "half "+s, off+4, 4, suffix))
		}

	case asmEmptyInterface:
		cc = append(cc, newComponent(suffix+"_type", asmKind(arch.ptrSize), "interface type", off, arch.ptrSize, suffix))
		cc = append(cc, newComponent(suffix+"_data", asmKind(arch.ptrSize), "interface data", off+arch.ptrSize, arch.ptrSize, suffix))

	case asmInterface:
		cc = append(cc, newComponent(suffix+"_itable", asmKind(arch.ptrSize), "interface itable", off, arch.ptrSize, suffix))
		cc = append(cc, newComponent(suffix+"_data", asmKind(arch.ptrSize), "interface data", off+arch.ptrSize, arch.ptrSize, suffix))

	case asmSlice:
		cc = append(cc, newComponent(suffix+"_base", asmKind(arch.ptrSize), "slice base", off, arch.ptrSize, suffix))
		cc = append(cc, newComponent(suffix+"_len", asmKind(arch.intSize), "slice len", off+arch.ptrSize, arch.intSize, suffix))
		cc = append(cc, newComponent(suffix+"_cap", asmKind(arch.intSize), "slice cap", off+arch.ptrSize+arch.intSize, arch.intSize, suffix))

	case asmString:
		cc = append(cc, newComponent(suffix+"_base", asmKind(arch.ptrSize), "string base", off, arch.ptrSize, suffix))
		cc = append(cc, newComponent(suffix+"_len", asmKind(arch.intSize), "string len", off+arch.ptrSize, arch.intSize, suffix))

	case asmComplex:
		fsize := size / 2
		cc = append(cc, newComponent(suffix+"_real", asmKind(fsize), fmt.Sprintf("real(complex%d)", size*8), off, fsize, suffix))
		cc = append(cc, newComponent(suffix+"_imag", asmKind(fsize), fmt.Sprintf("imag(complex%d)", size*8), off+fsize, fsize, suffix))

	case asmStruct:
		tu := t.Underlying().(*types.Struct)
		fields := make([]*types.Var, tu.NumFields())
		for i := 0; i < tu.NumFields(); i++ {
			fields[i] = tu.Field(i)
		}
		offsets := arch.sizes.Offsetsof(fields)
		for i, f := range fields {
			cc = appendComponentsRecursive(arch, f.Type(), cc, suffix+"_"+f.Name(), off+int(offsets[i]))
		}

	case asmArray:
		tu := t.Underlying().(*types.Array)
		elem := tu.Elem()
		// Calculate offset of each element array.
		fields := []*types.Var{
			types.NewField(token.NoPos, nil, "fake0", elem, false),
			types.NewField(token.NoPos, nil, "fake1", elem, false),
		}
		offsets := arch.sizes.Offsetsof(fields)
		elemoff := int(offsets[1])
		for i := 0; i < int(tu.Len()); i++ {
			cc = appendComponentsRecursive(arch, elem, cc, suffix+"_"+strconv.Itoa(i), off+i*elemoff)
		}
	}

	return cc
}

// asmParseDecl parses a function decl for expected assembly variables.
func asmParseDecl(pass *analysis.Pass, decl *ast.FuncDecl) map[string]*asmFunc {
	var (
		arch   *asmArch
		fn     *asmFunc
		offset int
	)

	// addParams adds asmVars for each of the parameters in list.
	// isret indicates whether the list are the arguments or the return values.
	// TODO(adonovan): simplify by passing (*types.Signature).{Params,Results}
	// instead of list.
	addParams := func(list []*ast.Field, isret bool) {
		argnum := 0
		for _, fld := range list {
			t := pass.TypesInfo.Types[fld.Type].Type

			// Work around https://golang.org/issue/28277.
			if t == nil {
				if ell, ok := fld.Type.(*ast.Ellipsis); ok {
					t = types.NewSlice(pass.TypesInfo.Types[ell.Elt].Type)
				}
			}

			align := int(arch.sizes.Alignof(t))
			size := int(arch.sizes.Sizeof(t))
			offset += -offset & (align - 1)
			cc := componentsOfType(arch, t)

			// names is the list of names with this type.
			names := fld.Names
			if len(names) == 0 {
				// Anonymous args will be called arg, arg1, arg2, ...
				// Similarly so for return values: ret, ret1, ret2, ...
				name := "arg"
				if isret {
					name = "ret"
				}
				if argnum > 0 {
					name += strconv.Itoa(argnum)
				}
				names = []*ast.Ident{ast.NewIdent(name)}
			}
			argnum += len(names)

			// Create variable for each name.
			for _, id := range names {
				name := id.Name
				for _, c := range cc {
					outer := name + c.outer
					v := asmVar{
						name: name + c.suffix,
						kind: c.kind,
						typ:  c.typ,
						off:  offset + c.offset,
						size: c.size,
					}
					if vo := fn.vars[outer]; vo != nil {
						vo.inner = append(vo.inner, &v)
					}
					fn.vars[v.name] = &v
					for i := 0; i < v.size; i++ {
						fn.varByOffset[v.off+i] = &v
					}
				}
				offset += size
			}
		}
	}

	m := make(map[string]*asmFunc)
	for _, arch = range arches {
		fn = &asmFunc{
			arch:        arch,
			vars:        make(map[string]*asmVar),
			varByOffset: make(map[int]*asmVar),
		}
		offset = 0
		addParams(decl.Type.Params.List, false)
		if decl.Type.Results != nil && len(decl.Type.Results.List) > 0 {
			offset += -offset & (arch.maxAlign - 1)
			addParams(decl.Type.Results.List, true)
		}
		fn.size = offset
		m[arch.name] = fn
	}

	return m
}

// asmCheckVar checks a single variable reference.
func asmCheckVar(badf func(string, ...any), fn *asmFunc, line, expr string, off int, v *asmVar, archDef *asmArch) {
	m := asmOpcode.FindStringSubmatch(line)
	if m == nil {
		if !strings.HasPrefix(strings.TrimSpace(line), "//") {
			badf("cannot find assembly opcode")
		}
		return
	}

	addr := strings.HasPrefix(expr, "$")

	// Determine operand sizes from instruction.
	// Typically the suffix suffices, but there are exceptions.
	var src, dst, kind asmKind
	op := m[1]
	switch fn.arch.name + "." + op {
	case "386.FMOVLP":
		src, dst = 8, 4
	case "arm.MOVD":
		src = 8
	case "arm.MOVW":
		src = 4
	case "arm.MOVH", "arm.MOVHU":
		src = 2
	case "arm.MOVB", "arm.MOVBU":
		src = 1
	// LEA* opcodes don't really read the second arg.
	// They just take the address of it.
	case "386.LEAL":
		dst = 4
		addr = true
	case "amd64.LEAQ":
		dst = 8
		addr = true
	default:
		switch fn.arch.name {
		case "386", "amd64":
			if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "D") || strings.HasSuffix(op, "DP")) {
				// FMOVDP, FXCHD, etc
				src = 8
				break
			}
			if strings.HasPrefix(op, "P") && strings.HasSuffix(op, "RD") {
				// PINSRD, PEXTRD, etc
				src = 4
				break
			}
			if strings.HasPrefix(op, "F") && (strings.HasSuffix(op, "F") || strings.HasSuffix(op, "FP")) {
				// FMOVFP, FXCHF, etc
				src = 4
				break
			}
			if strings.HasSuffix(op, "SD") {
				// MOVSD, SQRTSD, etc
				src = 8
				break
			}
			if strings.HasSuffix(op, "SS") {
				// MOVSS, SQRTSS, etc
				src = 4
				break
			}
			if op == "MOVO" || op == "MOVOU" {
				src = 16
				break
			}
			if strings.HasPrefix(op, "SET") {
				// SETEQ, etc
				src = 1
				break
			}
			switch op[len(op)-1] {
			case 'B':
				src = 1
			case 'W':
				src = 2
			case 'L':
				src = 4
			case 'D', 'Q':
				src = 8
			}
		case "ppc64", "ppc64le":
			// Strip standard suffixes to reveal size letter.
			m := ppc64Suff.FindStringSubmatch(op)
			if m != nil {
				switch m[1][0] {
				case 'B':
					src = 1
				case 'H':
					src = 2
				case 'W':
					src = 4
				case 'D':
					src = 8
				}
			}
		case "loong64", "mips", "mipsle", "mips64", "mips64le":
			switch op {
			case "MOVB", "MOVBU":
				src = 1
			case "MOVH", "MOVHU":
				src = 2
			case "MOVW", "MOVWU", "MOVF":
				src = 4
			case "MOVV", "MOVD":
				src = 8
			}
		case "s390x":
			switch op {
			case "MOVB", "MOVBZ":
				src = 1
			case "MOVH", "MOVHZ":
				src = 2
			case "MOVW", "MOVWZ", "FMOVS":
				src = 4
			case "MOVD", "FMOVD":
				src = 8
			}
		}
	}
	if dst == 0 {
		dst = src
	}

	// Determine whether the match we're holding
	// is the first or second argument.
	if strings.Index(line, expr) > strings.Index(line, ",") {
		kind = dst
	} else {
		kind = src
	}

	vk := v.kind
	vs := v.size
	vt := v.typ
	switch vk {
	case asmInterface, asmEmptyInterface, asmString, asmSlice:
		// allow reference to first word (pointer)
		vk = v.inner[0].kind
		vs = v.inner[0].size
		vt = v.inner[0].typ
	case asmComplex:
		// Allow a single instruction to load both parts of a complex.
		if int(kind) == vs {
			kind = asmComplex
		}
	}
	if addr {
		vk = asmKind(archDef.ptrSize)
		vs = archDef.ptrSize
		vt = "address"
	}

	if off != v.off {
		var inner bytes.Buffer
		for i, vi := range v.inner {
			if len(v.inner) > 1 {
				fmt.Fprintf(&inner, ",")
			}
			fmt.Fprintf(&inner, " ")
			if i == len(v.inner)-1 {
				fmt.Fprintf(&inner, "or ")
			}
			fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
		}
		badf("invalid offset %s; expected %s+%d(FP)%s", expr, v.name, v.off, inner.String())
		return
	}
	if kind != 0 && kind != vk {
		var inner bytes.Buffer
		if len(v.inner) > 0 {
			fmt.Fprintf(&inner, " containing")
			for i, vi := range v.inner {
				if i > 0 && len(v.inner) > 2 {
					fmt.Fprintf(&inner, ",")
				}
				fmt.Fprintf(&inner, " ")
				if i > 0 && i == len(v.inner)-1 {
					fmt.Fprintf(&inner, "and ")
				}
				fmt.Fprintf(&inner, "%s+%d(FP)", vi.name, vi.off)
			}
		}
		badf("invalid %s of %s; %s is %d-byte value%s", op, expr, vt, vs, inner.String())
	}
}


================================================
FILE: go/analysis/passes/asmdecl/asmdecl_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package asmdecl_test

import (
	"os"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/asmdecl"
)

var goosarches = []string{
	"linux/amd64", // asm1.s, asm4.s
	"linux/386",   // asm2.s
	"linux/arm",   // asm3.s
	// TODO: skip test on loong64 until go toolchain supported loong64.
	// "linux/loong64", // asm10.s
	"linux/mips64",  // asm5.s
	"linux/s390x",   // asm6.s
	"linux/ppc64",   // asm7.s
	"linux/mips",    // asm8.s,
	"js/wasm",       // asm9.s
	"linux/riscv64", // asm11.s
}

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	for _, goosarch := range goosarches {
		t.Run(goosarch, func(t *testing.T) {
			i := strings.Index(goosarch, "/")
			os.Setenv("GOOS", goosarch[:i])
			os.Setenv("GOARCH", goosarch[i+1:])
			analysistest.Run(t, testdata, asmdecl.Analyzer, "a")
		})
	}
}


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains declarations to test the assembly in test_asm.s.

package a

type S struct {
	i int32
	b bool
	s string
}

func arg1(x int8, y uint8)
func arg2(x int16, y uint16)
func arg4(x int32, y uint32)
func arg8(x int64, y uint64)
func argint(x int, y uint)
func argptr(x *byte, y *byte, c chan int, m map[int]int, f func())
func argstring(x, y string)
func argslice(x, y []string)
func argiface(x interface{}, y interface {
	m()
})
func argcomplex(x complex64, y complex128)
func argstruct(x S, y struct{})
func argarray(x [2]S)
func returnint() int
func returnbyte(x int) byte
func returnnamed(x byte) (r1 int, r2 int16, r3 string, r4 byte)
func returnintmissing() int
func leaf(x, y int) int

func noprof(x int)
func dupok(x int)
func nosplit(x int)
func rodata(x int)
func noptr(x int)
func wrapper(x int)

func f15271() (x uint32)
func f17584(x float32, y complex64)
func f29318(x [2][2]uint64)

func noframe1(x int32)
func noframe2(x int32)

func fvariadic(int, ...int)

func pickStableABI(x int)
func pickInternalABI(x int)
func pickFutureABI(x int)

func returnABIInternal() int
func returnmissingABIInternal() int
func returnsyscallABIInternal() int

func retjmp() int


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm1.s
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build amd64

// Commented-out code should be ignored.
//
//	TEXT ·unknown(SB),0,$0
//		RET

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), AX
	// MOVB x+0(FP), AX // commented out instructions used to panic
	MOVB	y+1(FP), BX
	MOVW	x+0(FP), AX // want `\[amd64\] arg1: invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVW	y+1(FP), AX // want `invalid MOVW of y\+1\(FP\); uint8 is 1-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int8 is 1-byte value`
	MOVL	y+1(FP), AX // want `invalid MOVL of y\+1\(FP\); uint8 is 1-byte value`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int8 is 1-byte value`
	MOVQ	y+1(FP), AX // want `invalid MOVQ of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), AX // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVB	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	TESTB	x+0(FP), AX
	TESTB	y+1(FP), BX
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int8 is 1-byte value`
	TESTW	y+1(FP), AX // want `invalid TESTW of y\+1\(FP\); uint8 is 1-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int8 is 1-byte value`
	TESTL	y+1(FP), AX // want `invalid TESTL of y\+1\(FP\); uint8 is 1-byte value`
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int8 is 1-byte value`
	TESTQ	y+1(FP), AX // want `invalid TESTQ of y\+1\(FP\); uint8 is 1-byte value`
	TESTB	x+1(FP), AX // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	TESTB	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	8(SP), AX // want `8\(SP\) should be x\+0\(FP\)`
	MOVB	9(SP), AX // want `9\(SP\) should be y\+1\(FP\)`
	MOVB	10(SP), AX // want `use of 10\(SP\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVB	x+0(FP), AX // want `arg2: invalid MOVB of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), AX // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVW	x+0(FP), AX
	MOVW	y+2(FP), BX
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int16 is 2-byte value`
	MOVL	y+2(FP), AX // want `invalid MOVL of y\+2\(FP\); uint16 is 2-byte value`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int16 is 2-byte value`
	MOVQ	y+2(FP), AX // want `invalid MOVQ of y\+2\(FP\); uint16 is 2-byte value`
	MOVW	x+2(FP), AX // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVW	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int16 is 2-byte value`
	TESTB	y+2(FP), AX // want `invalid TESTB of y\+2\(FP\); uint16 is 2-byte value`
	TESTW	x+0(FP), AX
	TESTW	y+2(FP), BX
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int16 is 2-byte value`
	TESTL	y+2(FP), AX // want `invalid TESTL of y\+2\(FP\); uint16 is 2-byte value`
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int16 is 2-byte value`
	TESTQ	y+2(FP), AX // want `invalid TESTQ of y\+2\(FP\); uint16 is 2-byte value`
	TESTW	x+2(FP), AX // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	TESTW	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int32 is 4-byte value`
	MOVW	y+4(FP), AX // want `invalid MOVW of y\+4\(FP\); uint32 is 4-byte value`
	MOVL	x+0(FP), AX
	MOVL	y+4(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int32 is 4-byte value`
	MOVQ	y+4(FP), AX // want `invalid MOVQ of y\+4\(FP\); uint32 is 4-byte value`
	MOVL	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVL	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int32 is 4-byte value`
	TESTB	y+4(FP), BX // want `invalid TESTB of y\+4\(FP\); uint32 is 4-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int32 is 4-byte value`
	TESTW	y+4(FP), AX // want `invalid TESTW of y\+4\(FP\); uint32 is 4-byte value`
	TESTL	x+0(FP), AX
	TESTL	y+4(FP), AX
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int32 is 4-byte value`
	TESTQ	y+4(FP), AX // want `invalid TESTQ of y\+4\(FP\); uint32 is 4-byte value`
	TESTL	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	TESTL	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), BX // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int64 is 8-byte value`
	MOVL	y+8(FP), AX // want `invalid MOVL of y\+8\(FP\); uint64 is 8-byte value`
	MOVQ	x+0(FP), AX
	MOVQ	y+8(FP), AX
	MOVQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int64 is 8-byte value`
	TESTB	y+8(FP), BX // want `invalid TESTB of y\+8\(FP\); uint64 is 8-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int64 is 8-byte value`
	TESTW	y+8(FP), AX // want `invalid TESTW of y\+8\(FP\); uint64 is 8-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int64 is 8-byte value`
	TESTL	y+8(FP), AX // want `invalid TESTL of y\+8\(FP\); uint64 is 8-byte value`
	TESTQ	x+0(FP), AX
	TESTQ	y+8(FP), AX
	TESTQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int is 8-byte value`
	MOVB	y+8(FP), BX // want `invalid MOVB of y\+8\(FP\); uint is 8-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int is 8-byte value`
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); uint is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int is 8-byte value`
	MOVL	y+8(FP), AX // want `invalid MOVL of y\+8\(FP\); uint is 8-byte value`
	MOVQ	x+0(FP), AX
	MOVQ	y+8(FP), AX
	MOVQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int is 8-byte value`
	TESTB	y+8(FP), BX // want `invalid TESTB of y\+8\(FP\); uint is 8-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int is 8-byte value`
	TESTW	y+8(FP), AX // want `invalid TESTW of y\+8\(FP\); uint is 8-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int is 8-byte value`
	TESTL	y+8(FP), AX // want `invalid TESTL of y\+8\(FP\); uint is 8-byte value`
	TESTQ	x+0(FP), AX
	TESTQ	y+8(FP), AX
	TESTQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-40`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); \*byte is 8-byte value`
	MOVB	y+8(FP), BX // want `invalid MOVB of y\+8\(FP\); \*byte is 8-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); \*byte is 8-byte value`
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); \*byte is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); \*byte is 8-byte value`
	MOVL	y+8(FP), AX // want `invalid MOVL of y\+8\(FP\); \*byte is 8-byte value`
	MOVQ	x+0(FP), AX
	MOVQ	y+8(FP), AX
	MOVQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); \*byte is 8-byte value`
	TESTB	y+8(FP), BX // want `invalid TESTB of y\+8\(FP\); \*byte is 8-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); \*byte is 8-byte value`
	TESTW	y+8(FP), AX // want `invalid TESTW of y\+8\(FP\); \*byte is 8-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); \*byte is 8-byte value`
	TESTL	y+8(FP), AX // want `invalid TESTL of y\+8\(FP\); \*byte is 8-byte value`
	TESTQ	x+0(FP), AX
	TESTQ	y+8(FP), AX
	TESTQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	MOVL	c+16(FP), AX // want `invalid MOVL of c\+16\(FP\); chan int is 8-byte value`
	MOVL	m+24(FP), AX // want `invalid MOVL of m\+24\(FP\); map\[int\]int is 8-byte value`
	MOVL	f+32(FP), AX // want `invalid MOVL of f\+32\(FP\); func\(\) is 8-byte value`
	RET

TEXT ·argstring(SB),0,$32 // want `wrong argument size 0; expected \$\.\.\.-32`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); string base is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); string base is 8-byte value`
	LEAQ	x+0(FP), AX // ok
	MOVQ	x+0(FP), AX
	MOVW	x_base+0(FP), AX // want `invalid MOVW of x_base\+0\(FP\); string base is 8-byte value`
	MOVL	x_base+0(FP), AX // want `invalid MOVL of x_base\+0\(FP\); string base is 8-byte value`
	MOVQ	x_base+0(FP), AX
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVL	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+8(FP), AX // want `invalid MOVW of x_len\+8\(FP\); string len is 8-byte value`
	MOVL	x_len+8(FP), AX // want `invalid MOVL of x_len\+8\(FP\); string len is 8-byte value`
	MOVQ	x_len+8(FP), AX
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+16\(FP\)`
	MOVQ	y_len+8(FP), AX // want `invalid offset y_len\+8\(FP\); expected y_len\+24\(FP\)`
	RET

TEXT ·argslice(SB),0,$48 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); slice base is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); slice base is 8-byte value`
	MOVQ	x+0(FP), AX
	MOVW	x_base+0(FP), AX // want `invalid MOVW of x_base\+0\(FP\); slice base is 8-byte value`
	MOVL	x_base+0(FP), AX // want `invalid MOVL of x_base\+0\(FP\); slice base is 8-byte value`
	MOVQ	x_base+0(FP), AX
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVL	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+8(FP), AX // want `invalid MOVW of x_len\+8\(FP\); slice len is 8-byte value`
	MOVL	x_len+8(FP), AX // want `invalid MOVL of x_len\+8\(FP\); slice len is 8-byte value`
	MOVQ	x_len+8(FP), AX
	MOVW	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVL	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVQ	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVW	x_cap+16(FP), AX // want `invalid MOVW of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVL	x_cap+16(FP), AX // want `invalid MOVL of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVQ	x_cap+16(FP), AX
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+24\(FP\)`
	MOVQ	y_len+8(FP), AX // want `invalid offset y_len\+8\(FP\); expected y_len\+32\(FP\)`
	MOVQ	y_cap+16(FP), AX // want `invalid offset y_cap\+16\(FP\); expected y_cap\+40\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-32
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); interface type is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); interface type is 8-byte value`
	MOVQ	x+0(FP), AX
	MOVW	x_type+0(FP), AX // want `invalid MOVW of x_type\+0\(FP\); interface type is 8-byte value`
	MOVL	x_type+0(FP), AX // want `invalid MOVL of x_type\+0\(FP\); interface type is 8-byte value`
	MOVQ	x_type+0(FP), AX
	MOVQ	x_itable+0(FP), AX // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVQ	x_itable+1(FP), AX // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVW	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVL	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVQ	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVW	x_data+8(FP), AX // want `invalid MOVW of x_data\+8\(FP\); interface data is 8-byte value`
	MOVL	x_data+8(FP), AX // want `invalid MOVL of x_data\+8\(FP\); interface data is 8-byte value`
	MOVQ	x_data+8(FP), AX
	MOVW	y+16(FP), AX // want `invalid MOVW of y\+16\(FP\); interface itable is 8-byte value`
	MOVL	y+16(FP), AX // want `invalid MOVL of y\+16\(FP\); interface itable is 8-byte value`
	MOVQ	y+16(FP), AX
	MOVW	y_itable+16(FP), AX // want `invalid MOVW of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVL	y_itable+16(FP), AX // want `invalid MOVL of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVQ	y_itable+16(FP), AX
	MOVQ	y_type+16(FP), AX // want `unknown variable y_type; offset 16 is y_itable\+16\(FP\)`
	MOVW	y_data+16(FP), AX // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVL	y_data+16(FP), AX // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVQ	y_data+16(FP), AX // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVW	y_data+24(FP), AX // want `invalid MOVW of y_data\+24\(FP\); interface data is 8-byte value`
	MOVL	y_data+24(FP), AX // want `invalid MOVL of y_data\+24\(FP\); interface data is 8-byte value`
	MOVQ	y_data+24(FP), AX
	RET

TEXT ·argcomplex(SB),0,$24 // want `wrong argument size 0; expected \$\.\.\.-24`
	MOVSS	x+0(FP), X0 // want `invalid MOVSS of x\+0\(FP\); complex64 is 8-byte value containing x_real\+0\(FP\) and x_imag\+4\(FP\)`
	MOVSS	x_real+0(FP), X0
	MOVSD	x_real+0(FP), X0 // want `invalid MOVSD of x_real\+0\(FP\); real\(complex64\) is 4-byte value`
	MOVSS	x_real+4(FP), X0 // want `invalid offset x_real\+4\(FP\); expected x_real\+0\(FP\)`
	MOVSS	x_imag+4(FP), X0
	MOVSD	x_imag+4(FP), X0 // want `invalid MOVSD of x_imag\+4\(FP\); imag\(complex64\) is 4-byte value`
	MOVSS	x_imag+8(FP), X0 // want `invalid offset x_imag\+8\(FP\); expected x_imag\+4\(FP\)`
	MOVSD	y+8(FP), X0 // want `invalid MOVSD of y\+8\(FP\); complex128 is 16-byte value containing y_real\+8\(FP\) and y_imag\+16\(FP\)`
	MOVSS	y_real+8(FP), X0 // want `invalid MOVSS of y_real\+8\(FP\); real\(complex128\) is 8-byte value`
	MOVSD	y_real+8(FP), X0
	MOVSS	y_real+16(FP), X0 // want `invalid offset y_real\+16\(FP\); expected y_real\+8\(FP\)`
	MOVSS	y_imag+16(FP), X0 // want `invalid MOVSS of y_imag\+16\(FP\); imag\(complex128\) is 8-byte value`
	MOVSD	y_imag+16(FP), X0
	MOVSS	y_imag+24(FP), X0 // want `invalid offset y_imag\+24\(FP\); expected y_imag\+16\(FP\)`
	// Loading both parts of a complex is ok: see issue 35264.
	MOVSD	x+0(FP), X0
	MOVO	y+8(FP), X0
	MOVOU	y+8(FP), X0
	// These are not ok.
	MOVO	x+0(FP), X0 // want `invalid MOVO of x\+0\(FP\); complex64 is 8-byte value containing x_real\+0\(FP\) and x_imag\+4\(FP\)`
	MOVOU	x+0(FP), X0 // want `invalid MOVOU of x\+0\(FP\); complex64 is 8-byte value containing x_real\+0\(FP\) and x_imag\+4\(FP\)`
	RET

TEXT ·argstruct(SB),0,$64 // want `wrong argument size 0; expected \$\.\.\.-24`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); a.S is 24-byte value`
	MOVQ	x_i+0(FP), AX // want `invalid MOVQ of x_i\+0\(FP\); int32 is 4-byte value`
	MOVQ	x_b+0(FP), AX // want `invalid offset x_b\+0\(FP\); expected x_b\+4\(FP\)`
	MOVQ	x_s+8(FP), AX
	MOVQ	x_s_base+8(FP), AX
	MOVQ	x_s+16(FP), AX // want `invalid offset x_s\+16\(FP\); expected x_s\+8\(FP\), x_s_base\+8\(FP\), or x_s_len\+16\(FP\)`
	MOVQ	x_s_len+16(FP), AX
	RET

TEXT ·argarray(SB),0,$64 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); \[2\]a.S is 48-byte value`
	MOVQ	x_0_i+0(FP), AX // want `invalid MOVQ of x_0_i\+0\(FP\); int32 is 4-byte value`
	MOVQ	x_0_b+0(FP), AX // want `invalid offset x_0_b\+0\(FP\); expected x_0_b\+4\(FP\)`
	MOVQ	x_0_s+8(FP), AX
	MOVQ	x_0_s_base+8(FP), AX
	MOVQ	x_0_s+16(FP), AX // want `invalid offset x_0_s\+16\(FP\); expected x_0_s\+8\(FP\), x_0_s_base\+8\(FP\), or x_0_s_len\+16\(FP\)`
	MOVQ	x_0_s_len+16(FP), AX
	MOVB	foo+25(FP), AX // want `unknown variable foo; offset 25 is x_1_i\+24\(FP\)`
	MOVQ	x_1_s+32(FP), AX
	MOVQ	x_1_s_base+32(FP), AX
	MOVQ	x_1_s+40(FP), AX // want `invalid offset x_1_s\+40\(FP\); expected x_1_s\+32\(FP\), x_1_s_base\+32\(FP\), or x_1_s_len\+40\(FP\)`
	MOVQ	x_1_s_len+40(FP), AX
	RET

TEXT ·returnint(SB),0,$0-8
	MOVB	AX, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 8-byte value`
	MOVW	AX, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 8-byte value`
	MOVL	AX, ret+0(FP) // want `invalid MOVL of ret\+0\(FP\); int is 8-byte value`
	MOVQ	AX, ret+0(FP)
	MOVQ	AX, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVQ	AX, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-9
	MOVQ	x+0(FP), AX
	MOVB	AX, ret+8(FP)
	MOVW	AX, ret+8(FP) // want `invalid MOVW of ret\+8\(FP\); byte is 1-byte value`
	MOVL	AX, ret+8(FP) // want `invalid MOVL of ret\+8\(FP\); byte is 1-byte value`
	MOVQ	AX, ret+8(FP) // want `invalid MOVQ of ret\+8\(FP\); byte is 1-byte value`
	MOVB	AX, ret+7(FP) // want `invalid offset ret\+7\(FP\); expected ret\+8\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-41
	MOVB	x+0(FP), AX
	MOVQ	AX, r1+8(FP)
	MOVW	AX, r2+16(FP)
	MOVQ	AX, r3+24(FP)
	MOVQ	AX, r3_base+24(FP)
	MOVQ	AX, r3_len+32(FP)
	MOVB	AX, r4+40(FP)
	MOVL	AX, r1+8(FP) // want `invalid MOVL of r1\+8\(FP\); int is 8-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-8
	RET // want `RET without writing to 8-byte ret\+0\(FP\)`

// issue 15271
TEXT ·f15271(SB), NOSPLIT, $0-4
    // Stick 123 into the low 32 bits of X0.
    MOVQ $123, AX
    PINSRD $0, AX, X0

    // Return them.
    PEXTRD $0, X0, x+0(FP)
    RET

// issue 17584
TEXT ·f17584(SB), NOSPLIT, $12
	MOVSS	x+0(FP), X0
	MOVSS	y_real+4(FP), X0
	MOVSS	y_imag+8(FP), X0
	RET

// issue 29318
TEXT ·f29318(SB), NOSPLIT, $32
	MOVQ	x_0_1+8(FP), AX
	MOVQ	x_1_1+24(FP), CX
	RET

// ABI selector
TEXT ·pickStableABI<ABI0>(SB), NOSPLIT, $32
	MOVQ	x+0(FP), AX
	RET

// ABI selector
TEXT ·pickInternalABI<ABIInternal>(SB), NOSPLIT, $32
	MOVQ	x+0(FP), AX
	RET

// ABI selector
TEXT ·pickFutureABI<ABISomethingNotyetInvented>(SB), NOSPLIT, $32
	MOVQ	x+0(FP), AX
	RET

// writing to result in ABIInternal function
TEXT ·returnABIInternal<ABIInternal>(SB), NOSPLIT, $32
	MOVQ	$123, AX
	RET
TEXT ·returnmissingABIInternal<ABIInternal>(SB), NOSPLIT, $32
	MOVQ	$123, CX
	RET // want `RET without writing to result register`

// issue 69352
TEXT ·returnsyscallABIInternal<ABIInternal>(SB), NOSPLIT, $0
	MOVQ	$123, CX
	SYSCALL
	RET

// return jump
TEXT ·retjmp(SB), NOSPLIT, $0-8
	RET	retjmp1(SB) // It's okay to not write results if there's a tail call.


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm10.s
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build loong64

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), R19
	MOVBU	y+1(FP), R18
	MOVH	x+0(FP), R19 // want `\[loong64\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVHU	y+1(FP), R19 // want `invalid MOVHU of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVWU	y+1(FP), R19 // want `invalid MOVWU of y\+1\(FP\); uint8 is 1-byte value`
	MOVV	x+0(FP), R19 // want `invalid MOVV of x\+0\(FP\); int8 is 1-byte value`
	MOVV	y+1(FP), R19 // want `invalid MOVV of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), R19 // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVBU	y+2(FP), R19 // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	16(R3), R19 // want `16\(R3\) should be x\+0\(FP\)`
	MOVB	17(R3), R19 // want `17\(R3\) should be y\+1\(FP\)`
	MOVB	18(R3), R19 // want `use of 18\(R3\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVBU	x+0(FP), R19 // want `arg2: invalid MOVBU of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), R19 // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+0(FP), R19
	MOVH	y+2(FP), R18
	MOVWU	x+0(FP), R19 // want `invalid MOVWU of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), R19 // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVV	x+0(FP), R19 // want `invalid MOVV of x\+0\(FP\); int16 is 2-byte value`
	MOVV	y+2(FP), R19 // want `invalid MOVV of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+2(FP), R19 // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), R19 // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R19 // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), R18 // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), R19 // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), R19
	MOVW	y+4(FP), R19
	MOVV	x+0(FP), R19 // want `invalid MOVV of x\+0\(FP\); int32 is 4-byte value`
	MOVV	y+4(FP), R19 // want `invalid MOVV of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+4(FP), R19 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R19 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R19 // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), R18 // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), R19 // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), R19 // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVV	x+0(FP), R19
	MOVV	y+8(FP), R19
	MOVV	x+8(FP), R19 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R19 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R19 // want `invalid MOVB of x\+0\(FP\); int is 8-byte value`
	MOVB	y+8(FP), R18 // want `invalid MOVB of y\+8\(FP\); uint is 8-byte value`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); int is 8-byte value`
	MOVH	y+8(FP), R19 // want `invalid MOVH of y\+8\(FP\); uint is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); int is 8-byte value`
	MOVW	y+8(FP), R19 // want `invalid MOVW of y\+8\(FP\); uint is 8-byte value`
	MOVV	x+0(FP), R19
	MOVV	y+8(FP), R19
	MOVV	x+8(FP), R19 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R19 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-40`
	MOVB	x+0(FP), R19 // want `invalid MOVB of x\+0\(FP\); \*byte is 8-byte value`
	MOVB	y+8(FP), R18 // want `invalid MOVB of y\+8\(FP\); \*byte is 8-byte value`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); \*byte is 8-byte value`
	MOVH	y+8(FP), R19 // want `invalid MOVH of y\+8\(FP\); \*byte is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); \*byte is 8-byte value`
	MOVW	y+8(FP), R19 // want `invalid MOVW of y\+8\(FP\); \*byte is 8-byte value`
	MOVV	x+0(FP), R19
	MOVV	y+8(FP), R19
	MOVV	x+8(FP), R19 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R19 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	MOVW	c+16(FP), R19 // want `invalid MOVW of c\+16\(FP\); chan int is 8-byte value`
	MOVW	m+24(FP), R19 // want `invalid MOVW of m\+24\(FP\); map\[int\]int is 8-byte value`
	MOVW	f+32(FP), R19 // want `invalid MOVW of f\+32\(FP\); func\(\) is 8-byte value`
	RET

TEXT ·argstring(SB),0,$32 // want `wrong argument size 0; expected \$\.\.\.-32`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); string base is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); string base is 8-byte value`
	MOVV	x+0(FP), R19
	MOVH	x_base+0(FP), R19 // want `invalid MOVH of x_base\+0\(FP\); string base is 8-byte value`
	MOVW	x_base+0(FP), R19 // want `invalid MOVW of x_base\+0\(FP\); string base is 8-byte value`
	MOVV	x_base+0(FP), R19
	MOVH	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVV	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R19 // want `invalid MOVH of x_len\+8\(FP\); string len is 8-byte value`
	MOVW	x_len+8(FP), R19 // want `invalid MOVW of x_len\+8\(FP\); string len is 8-byte value`
	MOVV	x_len+8(FP), R19
	MOVV	y+0(FP), R19 // want `invalid offset y\+0\(FP\); expected y\+16\(FP\)`
	MOVV	y_len+8(FP), R19 // want `invalid offset y_len\+8\(FP\); expected y_len\+24\(FP\)`
	RET

TEXT ·argslice(SB),0,$48 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); slice base is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); slice base is 8-byte value`
	MOVV	x+0(FP), R19
	MOVH	x_base+0(FP), R19 // want `invalid MOVH of x_base\+0\(FP\); slice base is 8-byte value`
	MOVW	x_base+0(FP), R19 // want `invalid MOVW of x_base\+0\(FP\); slice base is 8-byte value`
	MOVV	x_base+0(FP), R19
	MOVH	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVV	x_len+0(FP), R19 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R19 // want `invalid MOVH of x_len\+8\(FP\); slice len is 8-byte value`
	MOVW	x_len+8(FP), R19 // want `invalid MOVW of x_len\+8\(FP\); slice len is 8-byte value`
	MOVV	x_len+8(FP), R19
	MOVH	x_cap+0(FP), R19 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVW	x_cap+0(FP), R19 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVV	x_cap+0(FP), R19 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVH	x_cap+16(FP), R19 // want `invalid MOVH of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVW	x_cap+16(FP), R19 // want `invalid MOVW of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVV	x_cap+16(FP), R19
	MOVV	y+0(FP), R19 // want `invalid offset y\+0\(FP\); expected y\+24\(FP\)`
	MOVV	y_len+8(FP), R19 // want `invalid offset y_len\+8\(FP\); expected y_len\+32\(FP\)`
	MOVV	y_cap+16(FP), R19 // want `invalid offset y_cap\+16\(FP\); expected y_cap\+40\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-32
	MOVH	x+0(FP), R19 // want `invalid MOVH of x\+0\(FP\); interface type is 8-byte value`
	MOVW	x+0(FP), R19 // want `invalid MOVW of x\+0\(FP\); interface type is 8-byte value`
	MOVV	x+0(FP), R19
	MOVH	x_type+0(FP), R19 // want `invalid MOVH of x_type\+0\(FP\); interface type is 8-byte value`
	MOVW	x_type+0(FP), R19 // want `invalid MOVW of x_type\+0\(FP\); interface type is 8-byte value`
	MOVV	x_type+0(FP), R19
	MOVV	x_itable+0(FP), R19 // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVV	x_itable+1(FP), R19 // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), R19 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVW	x_data+0(FP), R19 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVV	x_data+0(FP), R19 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVH	x_data+8(FP), R19 // want `invalid MOVH of x_data\+8\(FP\); interface data is 8-byte value`
	MOVW	x_data+8(FP), R19 // want `invalid MOVW of x_data\+8\(FP\); interface data is 8-byte value`
	MOVV	x_data+8(FP), R19
	MOVH	y+16(FP), R19 // want `invalid MOVH of y\+16\(FP\); interface itable is 8-byte value`
	MOVW	y+16(FP), R19 // want `invalid MOVW of y\+16\(FP\); interface itable is 8-byte value`
	MOVV	y+16(FP), R19
	MOVH	y_itable+16(FP), R19 // want `invalid MOVH of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVW	y_itable+16(FP), R19 // want `invalid MOVW of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVV	y_itable+16(FP), R19
	MOVV	y_type+16(FP), R19 // want `unknown variable y_type; offset 16 is y_itable\+16\(FP\)`
	MOVH	y_data+16(FP), R19 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVW	y_data+16(FP), R19 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVV	y_data+16(FP), R19 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVH	y_data+24(FP), R19 // want `invalid MOVH of y_data\+24\(FP\); interface data is 8-byte value`
	MOVW	y_data+24(FP), R19 // want `invalid MOVW of y_data\+24\(FP\); interface data is 8-byte value`
	MOVV	y_data+24(FP), R19
	RET

TEXT ·returnint(SB),0,$0-8
	MOVB	R19, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 8-byte value`
	MOVH	R19, ret+0(FP) // want `invalid MOVH of ret\+0\(FP\); int is 8-byte value`
	MOVW	R19, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 8-byte value`
	MOVV	R19, ret+0(FP)
	MOVV	R19, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVV	R19, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-9
	MOVV	x+0(FP), R19
	MOVB	R19, ret+8(FP)
	MOVH	R19, ret+8(FP) // want `invalid MOVH of ret\+8\(FP\); byte is 1-byte value`
	MOVW	R19, ret+8(FP) // want `invalid MOVW of ret\+8\(FP\); byte is 1-byte value`
	MOVV	R19, ret+8(FP) // want `invalid MOVV of ret\+8\(FP\); byte is 1-byte value`
	MOVB	R19, ret+7(FP) // want `invalid offset ret\+7\(FP\); expected ret\+8\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-41
	MOVB	x+0(FP), R19
	MOVV	R19, r1+8(FP)
	MOVH	R19, r2+16(FP)
	MOVV	R19, r3+24(FP)
	MOVV	R19, r3_base+24(FP)
	MOVV	R19, r3_len+32(FP)
	MOVB	R19, r4+40(FP)
	MOVW	R19, r1+8(FP) // want `invalid MOVW of r1\+8\(FP\); int is 8-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-8
	RET // want `RET without writing to 8-byte ret\+0\(FP\)`


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm11.s
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build riscv64

// writing to result in ABIInternal function
TEXT ·returnABIInternal<ABIInternal>(SB), NOSPLIT, $8
	MOV	$123, X10
	RET
TEXT ·returnmissingABIInternal<ABIInternal>(SB), NOSPLIT, $8
	MOV	$123, X20
	RET // want `RET without writing to result register`

// issue 69352
TEXT ·returnsyscallABIInternal<ABIInternal>(SB), NOSPLIT, $0
	MOV	$123, X20
	ECALL
	RET


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm2.s
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build 386

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), AX
	MOVB	y+1(FP), BX
	MOVW	x+0(FP), AX // want `\[386\] arg1: invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVW	y+1(FP), AX // want `invalid MOVW of y\+1\(FP\); uint8 is 1-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int8 is 1-byte value`
	MOVL	y+1(FP), AX // want `invalid MOVL of y\+1\(FP\); uint8 is 1-byte value`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int8 is 1-byte value`
	MOVQ	y+1(FP), AX // want `invalid MOVQ of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), AX // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVB	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	TESTB	x+0(FP), AX
	TESTB	y+1(FP), BX
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int8 is 1-byte value`
	TESTW	y+1(FP), AX // want `invalid TESTW of y\+1\(FP\); uint8 is 1-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int8 is 1-byte value`
	TESTL	y+1(FP), AX // want `invalid TESTL of y\+1\(FP\); uint8 is 1-byte value`
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int8 is 1-byte value`
	TESTQ	y+1(FP), AX // want `invalid TESTQ of y\+1\(FP\); uint8 is 1-byte value`
	TESTB	x+1(FP), AX // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	TESTB	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	4(SP), AX // want `4\(SP\) should be x\+0\(FP\)`
	MOVB	5(SP), AX // want `5\(SP\) should be y\+1\(FP\)`
	MOVB	6(SP), AX // want `use of 6\(SP\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVB	x+0(FP), AX // want `arg2: invalid MOVB of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), AX // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVW	x+0(FP), AX
	MOVW	y+2(FP), BX
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int16 is 2-byte value`
	MOVL	y+2(FP), AX // want `invalid MOVL of y\+2\(FP\); uint16 is 2-byte value`
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int16 is 2-byte value`
	MOVQ	y+2(FP), AX // want `invalid MOVQ of y\+2\(FP\); uint16 is 2-byte value`
	MOVW	x+2(FP), AX // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVW	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int16 is 2-byte value`
	TESTB	y+2(FP), AX // want `invalid TESTB of y\+2\(FP\); uint16 is 2-byte value`
	TESTW	x+0(FP), AX
	TESTW	y+2(FP), BX
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int16 is 2-byte value`
	TESTL	y+2(FP), AX // want `invalid TESTL of y\+2\(FP\); uint16 is 2-byte value`
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int16 is 2-byte value`
	TESTQ	y+2(FP), AX // want `invalid TESTQ of y\+2\(FP\); uint16 is 2-byte value`
	TESTW	x+2(FP), AX // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	TESTW	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int32 is 4-byte value`
	MOVW	y+4(FP), AX // want `invalid MOVW of y\+4\(FP\); uint32 is 4-byte value`
	MOVL	x+0(FP), AX
	MOVL	y+4(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int32 is 4-byte value`
	MOVQ	y+4(FP), AX // want `invalid MOVQ of y\+4\(FP\); uint32 is 4-byte value`
	MOVL	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVL	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int32 is 4-byte value`
	TESTB	y+4(FP), BX // want `invalid TESTB of y\+4\(FP\); uint32 is 4-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int32 is 4-byte value`
	TESTW	y+4(FP), AX // want `invalid TESTW of y\+4\(FP\); uint32 is 4-byte value`
	TESTL	x+0(FP), AX
	TESTL	y+4(FP), AX
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int32 is 4-byte value`
	TESTQ	y+4(FP), AX // want `invalid TESTQ of y\+4\(FP\); uint32 is 4-byte value`
	TESTL	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	TESTL	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), BX // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVL	x+0(FP), AX // want `invalid MOVL of x\+0\(FP\); int64 is 8-byte value containing x_lo\+0\(FP\) and x_hi\+4\(FP\)`
	MOVL	x_lo+0(FP), AX
	MOVL	x_hi+4(FP), AX
	MOVL	y+8(FP), AX // want `invalid MOVL of y\+8\(FP\); uint64 is 8-byte value containing y_lo\+8\(FP\) and y_hi\+12\(FP\)`
	MOVL	y_lo+8(FP), AX
	MOVL	y_hi+12(FP), AX
	MOVQ	x+0(FP), AX
	MOVQ	y+8(FP), AX
	MOVQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int64 is 8-byte value`
	TESTB	y+8(FP), BX // want `invalid TESTB of y\+8\(FP\); uint64 is 8-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int64 is 8-byte value`
	TESTW	y+8(FP), AX // want `invalid TESTW of y\+8\(FP\); uint64 is 8-byte value`
	TESTL	x+0(FP), AX // want `invalid TESTL of x\+0\(FP\); int64 is 8-byte value containing x_lo\+0\(FP\) and x_hi\+4\(FP\)`
	TESTL	y+8(FP), AX // want `invalid TESTL of y\+8\(FP\); uint64 is 8-byte value containing y_lo\+8\(FP\) and y_hi\+12\(FP\)`
	TESTQ	x+0(FP), AX
	TESTQ	y+8(FP), AX
	TESTQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); uint is 4-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int is 4-byte value`
	MOVW	y+4(FP), AX // want `invalid MOVW of y\+4\(FP\); uint is 4-byte value`
	MOVL	x+0(FP), AX
	MOVL	y+4(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); int is 4-byte value`
	MOVQ	y+4(FP), AX // want `invalid MOVQ of y\+4\(FP\); uint is 4-byte value`
	MOVQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); int is 4-byte value`
	TESTB	y+4(FP), BX // want `invalid TESTB of y\+4\(FP\); uint is 4-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); int is 4-byte value`
	TESTW	y+4(FP), AX // want `invalid TESTW of y\+4\(FP\); uint is 4-byte value`
	TESTL	x+0(FP), AX
	TESTL	y+4(FP), AX
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); int is 4-byte value`
	TESTQ	y+4(FP), AX // want `invalid TESTQ of y\+4\(FP\); uint is 4-byte value`
	TESTQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-20`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); \*byte is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); \*byte is 4-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); \*byte is 4-byte value`
	MOVW	y+4(FP), AX // want `invalid MOVW of y\+4\(FP\); \*byte is 4-byte value`
	MOVL	x+0(FP), AX
	MOVL	y+4(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); \*byte is 4-byte value`
	MOVQ	y+4(FP), AX // want `invalid MOVQ of y\+4\(FP\); \*byte is 4-byte value`
	MOVQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	TESTB	x+0(FP), AX // want `invalid TESTB of x\+0\(FP\); \*byte is 4-byte value`
	TESTB	y+4(FP), BX // want `invalid TESTB of y\+4\(FP\); \*byte is 4-byte value`
	TESTW	x+0(FP), AX // want `invalid TESTW of x\+0\(FP\); \*byte is 4-byte value`
	TESTW	y+4(FP), AX // want `invalid TESTW of y\+4\(FP\); \*byte is 4-byte value`
	TESTL	x+0(FP), AX
	TESTL	y+4(FP), AX
	TESTQ	x+0(FP), AX // want `invalid TESTQ of x\+0\(FP\); \*byte is 4-byte value`
	TESTQ	y+4(FP), AX // want `invalid TESTQ of y\+4\(FP\); \*byte is 4-byte value`
	TESTQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	TESTQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	MOVW	c+8(FP), AX // want `invalid MOVW of c\+8\(FP\); chan int is 4-byte value`
	MOVW	m+12(FP), AX // want `invalid MOVW of m\+12\(FP\); map\[int\]int is 4-byte value`
	MOVW	f+16(FP), AX // want `invalid MOVW of f\+16\(FP\); func\(\) is 4-byte value`
	RET

TEXT ·argstring(SB),0,$16 // want `wrong argument size 0; expected \$\.\.\.-16`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); string base is 4-byte value`
	MOVL	x+0(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); string base is 4-byte value`
	MOVW	x_base+0(FP), AX // want `invalid MOVW of x_base\+0\(FP\); string base is 4-byte value`
	MOVL	x_base+0(FP), AX
	MOVQ	x_base+0(FP), AX // want `invalid MOVQ of x_base\+0\(FP\); string base is 4-byte value`
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVL	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+4(FP), AX // want `invalid MOVW of x_len\+4\(FP\); string len is 4-byte value`
	MOVL	x_len+4(FP), AX
	MOVQ	x_len+4(FP), AX // want `invalid MOVQ of x_len\+4\(FP\); string len is 4-byte value`
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+8\(FP\)`
	MOVQ	y_len+4(FP), AX // want `invalid offset y_len\+4\(FP\); expected y_len\+12\(FP\)`
	RET

TEXT ·argslice(SB),0,$24 // want `wrong argument size 0; expected \$\.\.\.-24`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); slice base is 4-byte value`
	MOVL	x+0(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); slice base is 4-byte value`
	MOVW	x_base+0(FP), AX // want `invalid MOVW of x_base\+0\(FP\); slice base is 4-byte value`
	MOVL	x_base+0(FP), AX
	MOVQ	x_base+0(FP), AX // want `invalid MOVQ of x_base\+0\(FP\); slice base is 4-byte value`
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVL	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+4(FP), AX // want `invalid MOVW of x_len\+4\(FP\); slice len is 4-byte value`
	MOVL	x_len+4(FP), AX
	MOVQ	x_len+4(FP), AX // want `invalid MOVQ of x_len\+4\(FP\); slice len is 4-byte value`
	MOVW	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVL	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVQ	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVW	x_cap+8(FP), AX // want `invalid MOVW of x_cap\+8\(FP\); slice cap is 4-byte value`
	MOVL	x_cap+8(FP), AX
	MOVQ	x_cap+8(FP), AX // want `invalid MOVQ of x_cap\+8\(FP\); slice cap is 4-byte value`
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+12\(FP\)`
	MOVQ	y_len+4(FP), AX // want `invalid offset y_len\+4\(FP\); expected y_len\+16\(FP\)`
	MOVQ	y_cap+8(FP), AX // want `invalid offset y_cap\+8\(FP\); expected y_cap\+20\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-16
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); interface type is 4-byte value`
	MOVL	x+0(FP), AX
	MOVQ	x+0(FP), AX // want `invalid MOVQ of x\+0\(FP\); interface type is 4-byte value`
	MOVW	x_type+0(FP), AX // want `invalid MOVW of x_type\+0\(FP\); interface type is 4-byte value`
	MOVL	x_type+0(FP), AX
	MOVQ	x_type+0(FP), AX // want `invalid MOVQ of x_type\+0\(FP\); interface type is 4-byte value`
	MOVQ	x_itable+0(FP), AX // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVQ	x_itable+1(FP), AX // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVW	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVL	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVQ	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVW	x_data+4(FP), AX // want `invalid MOVW of x_data\+4\(FP\); interface data is 4-byte value`
	MOVL	x_data+4(FP), AX
	MOVQ	x_data+4(FP), AX // want `invalid MOVQ of x_data\+4\(FP\); interface data is 4-byte value`
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); interface itable is 4-byte value`
	MOVL	y+8(FP), AX
	MOVQ	y+8(FP), AX // want `invalid MOVQ of y\+8\(FP\); interface itable is 4-byte value`
	MOVW	y_itable+8(FP), AX // want `invalid MOVW of y_itable\+8\(FP\); interface itable is 4-byte value`
	MOVL	y_itable+8(FP), AX
	MOVQ	y_itable+8(FP), AX // want `invalid MOVQ of y_itable\+8\(FP\); interface itable is 4-byte value`
	MOVQ	y_type+8(FP), AX // want `unknown variable y_type; offset 8 is y_itable\+8\(FP\)`
	MOVW	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVL	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVQ	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVW	y_data+12(FP), AX // want `invalid MOVW of y_data\+12\(FP\); interface data is 4-byte value`
	MOVL	y_data+12(FP), AX
	MOVQ	y_data+12(FP), AX // want `invalid MOVQ of y_data\+12\(FP\); interface data is 4-byte value`
	RET

TEXT ·returnint(SB),0,$0-4
	MOVB	AX, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 4-byte value`
	MOVW	AX, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 4-byte value`
	MOVL	AX, ret+0(FP)
	MOVQ	AX, ret+0(FP) // want `invalid MOVQ of ret\+0\(FP\); int is 4-byte value`
	MOVQ	AX, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVQ	AX, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-5
	MOVL	x+0(FP), AX
	MOVB	AX, ret+4(FP)
	MOVW	AX, ret+4(FP) // want `invalid MOVW of ret\+4\(FP\); byte is 1-byte value`
	MOVL	AX, ret+4(FP) // want `invalid MOVL of ret\+4\(FP\); byte is 1-byte value`
	MOVQ	AX, ret+4(FP) // want `invalid MOVQ of ret\+4\(FP\); byte is 1-byte value`
	MOVB	AX, ret+3(FP) // want `invalid offset ret\+3\(FP\); expected ret\+4\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-21
	MOVB	x+0(FP), AX
	MOVL	AX, r1+4(FP)
	MOVW	AX, r2+8(FP)
	MOVL	AX, r3+12(FP)
	MOVL	AX, r3_base+12(FP)
	MOVL	AX, r3_len+16(FP)
	MOVB	AX, r4+20(FP)
	MOVQ	AX, r1+4(FP) // want `invalid MOVQ of r1\+4\(FP\); int is 4-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-4
	RET // want `RET without writing to 4-byte ret\+0\(FP\)`


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm3.s
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build arm

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), AX
	MOVB	y+1(FP), BX
	MOVH	x+0(FP), AX // want `\[arm\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVH	y+1(FP), AX // want `invalid MOVH of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVW	y+1(FP), AX // want `invalid MOVW of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), AX // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVB	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	8(R13), AX // want `8\(R13\) should be x\+0\(FP\)`
	MOVB	9(R13), AX // want `9\(R13\) should be y\+1\(FP\)`
	MOVB	10(R13), AX // want `use of 10\(R13\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVB	x+0(FP), AX // want `arg2: invalid MOVB of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), AX // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVH	x+0(FP), AX
	MOVH	y+2(FP), BX
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), AX // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVH	x+2(FP), AX // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), AX // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), AX
	MOVW	y+4(FP), AX
	MOVW	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), BX // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), AX // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), AX // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value containing x_lo\+0\(FP\) and x_hi\+4\(FP\)`
	MOVW	x_lo+0(FP), AX
	MOVW	x_hi+4(FP), AX
	MOVW	y+8(FP), AX // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value containing y_lo\+8\(FP\) and y_hi\+12\(FP\)`
	MOVW	y_lo+8(FP), AX
	MOVW	y_hi+12(FP), AX
	MOVQ	x+0(FP), AX
	MOVQ	y+8(FP), AX
	MOVQ	x+8(FP), AX // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); int is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); uint is 4-byte value`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); int is 4-byte value`
	MOVH	y+4(FP), AX // want `invalid MOVH of y\+4\(FP\); uint is 4-byte value`
	MOVW	x+0(FP), AX
	MOVW	y+4(FP), AX
	MOVQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-20`
	MOVB	x+0(FP), AX // want `invalid MOVB of x\+0\(FP\); \*byte is 4-byte value`
	MOVB	y+4(FP), BX // want `invalid MOVB of y\+4\(FP\); \*byte is 4-byte value`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); \*byte is 4-byte value`
	MOVH	y+4(FP), AX // want `invalid MOVH of y\+4\(FP\); \*byte is 4-byte value`
	MOVW	x+0(FP), AX
	MOVW	y+4(FP), AX
	MOVQ	x+4(FP), AX // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVQ	y+2(FP), AX // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	MOVH	c+8(FP), AX // want `invalid MOVH of c\+8\(FP\); chan int is 4-byte value`
	MOVH	m+12(FP), AX // want `invalid MOVH of m\+12\(FP\); map\[int\]int is 4-byte value`
	MOVH	f+16(FP), AX // want `invalid MOVH of f\+16\(FP\); func\(\) is 4-byte value`
	RET

TEXT ·argstring(SB),0,$16 // want `wrong argument size 0; expected \$\.\.\.-16`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); string base is 4-byte value`
	MOVW	x+0(FP), AX
	MOVH	x_base+0(FP), AX // want `invalid MOVH of x_base\+0\(FP\); string base is 4-byte value`
	MOVW	x_base+0(FP), AX
	MOVH	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVH	x_len+4(FP), AX // want `invalid MOVH of x_len\+4\(FP\); string len is 4-byte value`
	MOVW	x_len+4(FP), AX
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+8\(FP\)`
	MOVQ	y_len+4(FP), AX // want `invalid offset y_len\+4\(FP\); expected y_len\+12\(FP\)`
	RET

TEXT ·argslice(SB),0,$24 // want `wrong argument size 0; expected \$\.\.\.-24`
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); slice base is 4-byte value`
	MOVW	x+0(FP), AX
	MOVH	x_base+0(FP), AX // want `invalid MOVH of x_base\+0\(FP\); slice base is 4-byte value`
	MOVW	x_base+0(FP), AX
	MOVH	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVQ	x_len+0(FP), AX // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVH	x_len+4(FP), AX // want `invalid MOVH of x_len\+4\(FP\); slice len is 4-byte value`
	MOVW	x_len+4(FP), AX
	MOVH	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVW	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVQ	x_cap+0(FP), AX // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVH	x_cap+8(FP), AX // want `invalid MOVH of x_cap\+8\(FP\); slice cap is 4-byte value`
	MOVW	x_cap+8(FP), AX
	MOVQ	y+0(FP), AX // want `invalid offset y\+0\(FP\); expected y\+12\(FP\)`
	MOVQ	y_len+4(FP), AX // want `invalid offset y_len\+4\(FP\); expected y_len\+16\(FP\)`
	MOVQ	y_cap+8(FP), AX // want `invalid offset y_cap\+8\(FP\); expected y_cap\+20\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-16
	MOVH	x+0(FP), AX // want `invalid MOVH of x\+0\(FP\); interface type is 4-byte value`
	MOVW	x+0(FP), AX
	MOVH	x_type+0(FP), AX // want `invalid MOVH of x_type\+0\(FP\); interface type is 4-byte value`
	MOVW	x_type+0(FP), AX
	MOVQ	x_itable+0(FP), AX // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVQ	x_itable+1(FP), AX // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVW	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVQ	x_data+0(FP), AX // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVH	x_data+4(FP), AX // want `invalid MOVH of x_data\+4\(FP\); interface data is 4-byte value`
	MOVW	x_data+4(FP), AX
	MOVH	y+8(FP), AX // want `invalid MOVH of y\+8\(FP\); interface itable is 4-byte value`
	MOVW	y+8(FP), AX
	MOVH	y_itable+8(FP), AX // want `invalid MOVH of y_itable\+8\(FP\); interface itable is 4-byte value`
	MOVW	y_itable+8(FP), AX
	MOVQ	y_type+8(FP), AX // want `unknown variable y_type; offset 8 is y_itable\+8\(FP\)`
	MOVH	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVW	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVQ	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVH	y_data+12(FP), AX // want `invalid MOVH of y_data\+12\(FP\); interface data is 4-byte value`
	MOVW	y_data+12(FP), AX
	RET

TEXT ·returnint(SB),0,$0-4
	MOVB	AX, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 4-byte value`
	MOVH	AX, ret+0(FP) // want `invalid MOVH of ret\+0\(FP\); int is 4-byte value`
	MOVW	AX, ret+0(FP)
	MOVQ	AX, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVQ	AX, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-5
	MOVW	x+0(FP), AX
	MOVB	AX, ret+4(FP)
	MOVH	AX, ret+4(FP) // want `invalid MOVH of ret\+4\(FP\); byte is 1-byte value`
	MOVW	AX, ret+4(FP) // want `invalid MOVW of ret\+4\(FP\); byte is 1-byte value`
	MOVB	AX, ret+3(FP) // want `invalid offset ret\+3\(FP\); expected ret\+4\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-21
	MOVB	x+0(FP), AX
	MOVW	AX, r1+4(FP)
	MOVH	AX, r2+8(FP)
	MOVW	AX, r3+12(FP)
	MOVW	AX, r3_base+12(FP)
	MOVW	AX, r3_len+16(FP)
	MOVB	AX, r4+20(FP)
	MOVB	AX, r1+4(FP) // want `invalid MOVB of r1\+4\(FP\); int is 4-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-4
	RET // want `RET without writing to 4-byte ret\+0\(FP\)`

TEXT ·leaf(SB),0,$-4-12
	MOVW	x+0(FP), AX
	MOVW	y+4(FP), AX
	MOVW	AX, ret+8(FP)
	RET

TEXT ·noframe1(SB),0,$0-4
	MOVW	0(R13), AX // Okay; our saved LR
	MOVW	4(R13), AX // Okay; caller's saved LR
	MOVW	x+8(R13), AX // Okay; x argument
	MOVW	12(R13), AX // want `use of 12\(R13\) points beyond argument frame`
	RET

TEXT ·noframe2(SB),NOFRAME,$0-4
	MOVW	0(R13), AX // Okay; caller's saved LR
	MOVW	x+4(R13), AX // Okay; x argument
	MOVW	8(R13), AX // Okay - NOFRAME is assumed special
	MOVW	12(R13), AX // Okay - NOFRAME is assumed special
	RET


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm4.s
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build amd64

// Test cases for symbolic NOSPLIT etc. on TEXT symbols.

TEXT ·noprof(SB),NOPROF,$0-8
	RET

TEXT ·dupok(SB),DUPOK,$0-8
	RET

TEXT ·nosplit(SB),NOSPLIT,$0
	RET

TEXT ·rodata(SB),RODATA,$0-8
	RET

TEXT ·noptr(SB),NOPTR|NOSPLIT,$0
	RET

TEXT ·wrapper(SB),WRAPPER,$0-8
	RET


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm5.s
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build mips64

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), R1
	MOVBU	y+1(FP), R2
	MOVH	x+0(FP), R1 // want `\[mips64\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVHU	y+1(FP), R1 // want `invalid MOVHU of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVWU	y+1(FP), R1 // want `invalid MOVWU of y\+1\(FP\); uint8 is 1-byte value`
	MOVV	x+0(FP), R1 // want `invalid MOVV of x\+0\(FP\); int8 is 1-byte value`
	MOVV	y+1(FP), R1 // want `invalid MOVV of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), R1 // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVBU	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	16(R29), R1 // want `16\(R29\) should be x\+0\(FP\)`
	MOVB	17(R29), R1 // want `17\(R29\) should be y\+1\(FP\)`
	MOVB	18(R29), R1 // want `use of 18\(R29\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVBU	x+0(FP), R1 // want `arg2: invalid MOVBU of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), R1 // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+0(FP), R1
	MOVH	y+2(FP), R2
	MOVWU	x+0(FP), R1 // want `invalid MOVWU of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), R1 // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVV	x+0(FP), R1 // want `invalid MOVV of x\+0\(FP\); int16 is 2-byte value`
	MOVV	y+2(FP), R1 // want `invalid MOVV of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+2(FP), R1 // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), R2 // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), R1 // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), R1
	MOVW	y+4(FP), R1
	MOVV	x+0(FP), R1 // want `invalid MOVV of x\+0\(FP\); int32 is 4-byte value`
	MOVV	y+4(FP), R1 // want `invalid MOVV of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+4(FP), R1 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVV	x+0(FP), R1
	MOVV	y+8(FP), R1
	MOVV	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); uint is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); uint is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); uint is 8-byte value`
	MOVV	x+0(FP), R1
	MOVV	y+8(FP), R1
	MOVV	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-40`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); \*byte is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); \*byte is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); \*byte is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); \*byte is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); \*byte is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); \*byte is 8-byte value`
	MOVV	x+0(FP), R1
	MOVV	y+8(FP), R1
	MOVV	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVV	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	MOVW	c+16(FP), R1 // want `invalid MOVW of c\+16\(FP\); chan int is 8-byte value`
	MOVW	m+24(FP), R1 // want `invalid MOVW of m\+24\(FP\); map\[int\]int is 8-byte value`
	MOVW	f+32(FP), R1 // want `invalid MOVW of f\+32\(FP\); func\(\) is 8-byte value`
	RET

TEXT ·argstring(SB),0,$32 // want `wrong argument size 0; expected \$\.\.\.-32`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); string base is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); string base is 8-byte value`
	MOVV	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); string base is 8-byte value`
	MOVW	x_base+0(FP), R1 // want `invalid MOVW of x_base\+0\(FP\); string base is 8-byte value`
	MOVV	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVV	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R1 // want `invalid MOVH of x_len\+8\(FP\); string len is 8-byte value`
	MOVW	x_len+8(FP), R1 // want `invalid MOVW of x_len\+8\(FP\); string len is 8-byte value`
	MOVV	x_len+8(FP), R1
	MOVV	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+16\(FP\)`
	MOVV	y_len+8(FP), R1 // want `invalid offset y_len\+8\(FP\); expected y_len\+24\(FP\)`
	RET

TEXT ·argslice(SB),0,$48 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); slice base is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); slice base is 8-byte value`
	MOVV	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); slice base is 8-byte value`
	MOVW	x_base+0(FP), R1 // want `invalid MOVW of x_base\+0\(FP\); slice base is 8-byte value`
	MOVV	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVV	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R1 // want `invalid MOVH of x_len\+8\(FP\); slice len is 8-byte value`
	MOVW	x_len+8(FP), R1 // want `invalid MOVW of x_len\+8\(FP\); slice len is 8-byte value`
	MOVV	x_len+8(FP), R1
	MOVH	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVW	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVV	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVH	x_cap+16(FP), R1 // want `invalid MOVH of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVW	x_cap+16(FP), R1 // want `invalid MOVW of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVV	x_cap+16(FP), R1
	MOVV	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+24\(FP\)`
	MOVV	y_len+8(FP), R1 // want `invalid offset y_len\+8\(FP\); expected y_len\+32\(FP\)`
	MOVV	y_cap+16(FP), R1 // want `invalid offset y_cap\+16\(FP\); expected y_cap\+40\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-32
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); interface type is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); interface type is 8-byte value`
	MOVV	x+0(FP), R1
	MOVH	x_type+0(FP), R1 // want `invalid MOVH of x_type\+0\(FP\); interface type is 8-byte value`
	MOVW	x_type+0(FP), R1 // want `invalid MOVW of x_type\+0\(FP\); interface type is 8-byte value`
	MOVV	x_type+0(FP), R1
	MOVV	x_itable+0(FP), R1 // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVV	x_itable+1(FP), R1 // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVW	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVV	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVH	x_data+8(FP), R1 // want `invalid MOVH of x_data\+8\(FP\); interface data is 8-byte value`
	MOVW	x_data+8(FP), R1 // want `invalid MOVW of x_data\+8\(FP\); interface data is 8-byte value`
	MOVV	x_data+8(FP), R1
	MOVH	y+16(FP), R1 // want `invalid MOVH of y\+16\(FP\); interface itable is 8-byte value`
	MOVW	y+16(FP), R1 // want `invalid MOVW of y\+16\(FP\); interface itable is 8-byte value`
	MOVV	y+16(FP), R1
	MOVH	y_itable+16(FP), R1 // want `invalid MOVH of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVW	y_itable+16(FP), R1 // want `invalid MOVW of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVV	y_itable+16(FP), R1
	MOVV	y_type+16(FP), R1 // want `unknown variable y_type; offset 16 is y_itable\+16\(FP\)`
	MOVH	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVW	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVV	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVH	y_data+24(FP), R1 // want `invalid MOVH of y_data\+24\(FP\); interface data is 8-byte value`
	MOVW	y_data+24(FP), R1 // want `invalid MOVW of y_data\+24\(FP\); interface data is 8-byte value`
	MOVV	y_data+24(FP), R1
	RET

TEXT ·returnint(SB),0,$0-8
	MOVB	R1, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 8-byte value`
	MOVH	R1, ret+0(FP) // want `invalid MOVH of ret\+0\(FP\); int is 8-byte value`
	MOVW	R1, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 8-byte value`
	MOVV	R1, ret+0(FP)
	MOVV	R1, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVV	R1, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-9
	MOVV	x+0(FP), R1
	MOVB	R1, ret+8(FP)
	MOVH	R1, ret+8(FP) // want `invalid MOVH of ret\+8\(FP\); byte is 1-byte value`
	MOVW	R1, ret+8(FP) // want `invalid MOVW of ret\+8\(FP\); byte is 1-byte value`
	MOVV	R1, ret+8(FP) // want `invalid MOVV of ret\+8\(FP\); byte is 1-byte value`
	MOVB	R1, ret+7(FP) // want `invalid offset ret\+7\(FP\); expected ret\+8\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-41
	MOVB	x+0(FP), R1
	MOVV	R1, r1+8(FP)
	MOVH	R1, r2+16(FP)
	MOVV	R1, r3+24(FP)
	MOVV	R1, r3_base+24(FP)
	MOVV	R1, r3_len+32(FP)
	MOVB	R1, r4+40(FP)
	MOVW	R1, r1+8(FP) // want `invalid MOVW of r1\+8\(FP\); int is 8-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-8
	RET // want `RET without writing to 8-byte ret\+0\(FP\)`


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm6.s
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build s390x

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), R1
	MOVBZ	y+1(FP), R2
	MOVH	x+0(FP), R1 // want `\[s390x\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVHZ	y+1(FP), R1 // want `invalid MOVHZ of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVWZ	y+1(FP), R1 // want `invalid MOVWZ of y\+1\(FP\); uint8 is 1-byte value`
	MOVD	x+0(FP), R1 // want `invalid MOVD of x\+0\(FP\); int8 is 1-byte value`
	MOVD	y+1(FP), R1 // want `invalid MOVD of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), R1 // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVBZ	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	16(R15), R1 // want `16\(R15\) should be x\+0\(FP\)`
	MOVB	17(R15), R1 // want `17\(R15\) should be y\+1\(FP\)`
	MOVB	18(R15), R1 // want `use of 18\(R15\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVBZ	x+0(FP), R1 // want `arg2: invalid MOVBZ of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), R1 // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVHZ	x+0(FP), R1
	MOVH	y+2(FP), R2
	MOVWZ	x+0(FP), R1 // want `invalid MOVWZ of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), R1 // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVD	x+0(FP), R1 // want `invalid MOVD of x\+0\(FP\); int16 is 2-byte value`
	MOVD	y+2(FP), R1 // want `invalid MOVD of y\+2\(FP\); uint16 is 2-byte value`
	MOVHZ	x+2(FP), R1 // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), R2 // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), R1 // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), R1
	MOVW	y+4(FP), R1
	MOVD	x+0(FP), R1 // want `invalid MOVD of x\+0\(FP\); int32 is 4-byte value`
	MOVD	y+4(FP), R1 // want `invalid MOVD of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+4(FP), R1 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVD	x+0(FP), R1
	MOVD	y+8(FP), R1
	MOVD	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); uint is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); uint is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); uint is 8-byte value`
	MOVD	x+0(FP), R1
	MOVD	y+8(FP), R1
	MOVD	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-40`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); \*byte is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); \*byte is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); \*byte is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); \*byte is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); \*byte is 8-byte value`
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); \*byte is 8-byte value`
	MOVD	x+0(FP), R1
	MOVD	y+8(FP), R1
	MOVD	x+8(FP), R1 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	MOVW	c+16(FP), R1 // want `invalid MOVW of c\+16\(FP\); chan int is 8-byte value`
	MOVW	m+24(FP), R1 // want `invalid MOVW of m\+24\(FP\); map\[int\]int is 8-byte value`
	MOVW	f+32(FP), R1 // want `invalid MOVW of f\+32\(FP\); func\(\) is 8-byte value`
	RET

TEXT ·argstring(SB),0,$32 // want `wrong argument size 0; expected \$\.\.\.-32`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); string base is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); string base is 8-byte value`
	MOVD	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); string base is 8-byte value`
	MOVW	x_base+0(FP), R1 // want `invalid MOVW of x_base\+0\(FP\); string base is 8-byte value`
	MOVD	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVD	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R1 // want `invalid MOVH of x_len\+8\(FP\); string len is 8-byte value`
	MOVW	x_len+8(FP), R1 // want `invalid MOVW of x_len\+8\(FP\); string len is 8-byte value`
	MOVD	x_len+8(FP), R1
	MOVD	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+16\(FP\)`
	MOVD	y_len+8(FP), R1 // want `invalid offset y_len\+8\(FP\); expected y_len\+24\(FP\)`
	RET

TEXT ·argslice(SB),0,$48 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); slice base is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); slice base is 8-byte value`
	MOVD	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); slice base is 8-byte value`
	MOVW	x_base+0(FP), R1 // want `invalid MOVW of x_base\+0\(FP\); slice base is 8-byte value`
	MOVD	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVD	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R1 // want `invalid MOVH of x_len\+8\(FP\); slice len is 8-byte value`
	MOVW	x_len+8(FP), R1 // want `invalid MOVW of x_len\+8\(FP\); slice len is 8-byte value`
	MOVD	x_len+8(FP), R1
	MOVH	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVW	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVD	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVH	x_cap+16(FP), R1 // want `invalid MOVH of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVW	x_cap+16(FP), R1 // want `invalid MOVW of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVD	x_cap+16(FP), R1
	MOVD	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+24\(FP\)`
	MOVD	y_len+8(FP), R1 // want `invalid offset y_len\+8\(FP\); expected y_len\+32\(FP\)`
	MOVD	y_cap+16(FP), R1 // want `invalid offset y_cap\+16\(FP\); expected y_cap\+40\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-32
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); interface type is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); interface type is 8-byte value`
	MOVD	x+0(FP), R1
	MOVH	x_type+0(FP), R1 // want `invalid MOVH of x_type\+0\(FP\); interface type is 8-byte value`
	MOVW	x_type+0(FP), R1 // want `invalid MOVW of x_type\+0\(FP\); interface type is 8-byte value`
	MOVD	x_type+0(FP), R1
	MOVD	x_itable+0(FP), R1 // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVD	x_itable+1(FP), R1 // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVW	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVD	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVH	x_data+8(FP), R1 // want `invalid MOVH of x_data\+8\(FP\); interface data is 8-byte value`
	MOVW	x_data+8(FP), R1 // want `invalid MOVW of x_data\+8\(FP\); interface data is 8-byte value`
	MOVD	x_data+8(FP), R1
	MOVH	y+16(FP), R1 // want `invalid MOVH of y\+16\(FP\); interface itable is 8-byte value`
	MOVW	y+16(FP), R1 // want `invalid MOVW of y\+16\(FP\); interface itable is 8-byte value`
	MOVD	y+16(FP), R1
	MOVH	y_itable+16(FP), R1 // want `invalid MOVH of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVW	y_itable+16(FP), R1 // want `invalid MOVW of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVD	y_itable+16(FP), R1
	MOVD	y_type+16(FP), R1 // want `unknown variable y_type; offset 16 is y_itable\+16\(FP\)`
	MOVH	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVW	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVD	y_data+16(FP), R1 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVH	y_data+24(FP), R1 // want `invalid MOVH of y_data\+24\(FP\); interface data is 8-byte value`
	MOVW	y_data+24(FP), R1 // want `invalid MOVW of y_data\+24\(FP\); interface data is 8-byte value`
	MOVD	y_data+24(FP), R1
	RET

TEXT ·returnint(SB),0,$0-8
	MOVB	R1, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 8-byte value`
	MOVH	R1, ret+0(FP) // want `invalid MOVH of ret\+0\(FP\); int is 8-byte value`
	MOVW	R1, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 8-byte value`
	MOVD	R1, ret+0(FP)
	MOVD	R1, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVD	R1, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-9
	MOVD	x+0(FP), R1
	MOVB	R1, ret+8(FP)
	MOVH	R1, ret+8(FP) // want `invalid MOVH of ret\+8\(FP\); byte is 1-byte value`
	MOVW	R1, ret+8(FP) // want `invalid MOVW of ret\+8\(FP\); byte is 1-byte value`
	MOVD	R1, ret+8(FP) // want `invalid MOVD of ret\+8\(FP\); byte is 1-byte value`
	MOVB	R1, ret+7(FP) // want `invalid offset ret\+7\(FP\); expected ret\+8\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-41
	MOVB	x+0(FP), R1
	MOVD	R1, r1+8(FP)
	MOVH	R1, r2+16(FP)
	MOVD	R1, r3+24(FP)
	MOVD	R1, r3_base+24(FP)
	MOVD	R1, r3_len+32(FP)
	MOVB	R1, r4+40(FP)
	MOVW	R1, r1+8(FP) // want `invalid MOVW of r1\+8\(FP\); int is 8-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-8
	RET // want `RET without writing to 8-byte ret\+0\(FP\)`


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm7.s
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ppc64 ppc64le

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), R3
	MOVBZ	y+1(FP), R4
	MOVH	x+0(FP), R3 // want `\[(ppc64|ppc64le)\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVHZ	y+1(FP), R3 // want `invalid MOVHZ of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVWZ	y+1(FP), R3 // want `invalid MOVWZ of y\+1\(FP\); uint8 is 1-byte value`
	MOVD	x+0(FP), R3 // want `invalid MOVD of x\+0\(FP\); int8 is 1-byte value`
	MOVD	y+1(FP), R3 // want `invalid MOVD of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), R3 // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVBZ	y+2(FP), R3 // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	16(R1), R3 // want `16\(R1\) should be x\+0\(FP\)`
	MOVB	17(R1), R3 // want `17\(R1\) should be y\+1\(FP\)`
	MOVB	18(R1), R3 // want `use of 18\(R1\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVBZ	x+0(FP), R3 // want `arg2: invalid MOVBZ of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), R3 // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVHZ	x+0(FP), R3
	MOVH	y+2(FP), R4
	MOVWZ	x+0(FP), R3 // want `invalid MOVWZ of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), R3 // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVD	x+0(FP), R3 // want `invalid MOVD of x\+0\(FP\); int16 is 2-byte value`
	MOVD	y+2(FP), R3 // want `invalid MOVD of y\+2\(FP\); uint16 is 2-byte value`
	MOVHZ	x+2(FP), R3 // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), R3 // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R3 // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), R4 // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), R3 // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), R3
	MOVW	y+4(FP), R3
	MOVD	x+0(FP), R3 // want `invalid MOVD of x\+0\(FP\); int32 is 4-byte value`
	MOVD	y+4(FP), R3 // want `invalid MOVD of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+4(FP), R3 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R3 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R3 // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), R4 // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), R3 // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value`
	MOVW	y+8(FP), R3 // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value`
	MOVD	x+0(FP), R3
	MOVD	y+8(FP), R3
	MOVD	x+8(FP), R3 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R3 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R3 // want `invalid MOVB of x\+0\(FP\); int is 8-byte value`
	MOVB	y+8(FP), R4 // want `invalid MOVB of y\+8\(FP\); uint is 8-byte value`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); int is 8-byte value`
	MOVH	y+8(FP), R3 // want `invalid MOVH of y\+8\(FP\); uint is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); int is 8-byte value`
	MOVW	y+8(FP), R3 // want `invalid MOVW of y\+8\(FP\); uint is 8-byte value`
	MOVD	x+0(FP), R3
	MOVD	y+8(FP), R3
	MOVD	x+8(FP), R3 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R3 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-40`
	MOVB	x+0(FP), R3 // want `invalid MOVB of x\+0\(FP\); \*byte is 8-byte value`
	MOVB	y+8(FP), R4 // want `invalid MOVB of y\+8\(FP\); \*byte is 8-byte value`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); \*byte is 8-byte value`
	MOVH	y+8(FP), R3 // want `invalid MOVH of y\+8\(FP\); \*byte is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); \*byte is 8-byte value`
	MOVW	y+8(FP), R3 // want `invalid MOVW of y\+8\(FP\); \*byte is 8-byte value`
	MOVD	x+0(FP), R3
	MOVD	y+8(FP), R3
	MOVD	x+8(FP), R3 // want `invalid offset x\+8\(FP\); expected x\+0\(FP\)`
	MOVD	y+2(FP), R3 // want `invalid offset y\+2\(FP\); expected y\+8\(FP\)`
	MOVW	c+16(FP), R3 // want `invalid MOVW of c\+16\(FP\); chan int is 8-byte value`
	MOVW	m+24(FP), R3 // want `invalid MOVW of m\+24\(FP\); map\[int\]int is 8-byte value`
	MOVW	f+32(FP), R3 // want `invalid MOVW of f\+32\(FP\); func\(\) is 8-byte value`
	RET

TEXT ·argstring(SB),0,$32 // want `wrong argument size 0; expected \$\.\.\.-32`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); string base is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); string base is 8-byte value`
	MOVD	x+0(FP), R3
	MOVH	x_base+0(FP), R3 // want `invalid MOVH of x_base\+0\(FP\); string base is 8-byte value`
	MOVW	x_base+0(FP), R3 // want `invalid MOVW of x_base\+0\(FP\); string base is 8-byte value`
	MOVD	x_base+0(FP), R3
	MOVH	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVD	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R3 // want `invalid MOVH of x_len\+8\(FP\); string len is 8-byte value`
	MOVW	x_len+8(FP), R3 // want `invalid MOVW of x_len\+8\(FP\); string len is 8-byte value`
	MOVD	x_len+8(FP), R3
	MOVD	y+0(FP), R3 // want `invalid offset y\+0\(FP\); expected y\+16\(FP\)`
	MOVD	y_len+8(FP), R3 // want `invalid offset y_len\+8\(FP\); expected y_len\+24\(FP\)`
	RET

TEXT ·argslice(SB),0,$48 // want `wrong argument size 0; expected \$\.\.\.-48`
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); slice base is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); slice base is 8-byte value`
	MOVD	x+0(FP), R3
	MOVH	x_base+0(FP), R3 // want `invalid MOVH of x_base\+0\(FP\); slice base is 8-byte value`
	MOVW	x_base+0(FP), R3 // want `invalid MOVW of x_base\+0\(FP\); slice base is 8-byte value`
	MOVD	x_base+0(FP), R3
	MOVH	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVW	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVD	x_len+0(FP), R3 // want `invalid offset x_len\+0\(FP\); expected x_len\+8\(FP\)`
	MOVH	x_len+8(FP), R3 // want `invalid MOVH of x_len\+8\(FP\); slice len is 8-byte value`
	MOVW	x_len+8(FP), R3 // want `invalid MOVW of x_len\+8\(FP\); slice len is 8-byte value`
	MOVD	x_len+8(FP), R3
	MOVH	x_cap+0(FP), R3 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVW	x_cap+0(FP), R3 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVD	x_cap+0(FP), R3 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+16\(FP\)`
	MOVH	x_cap+16(FP), R3 // want `invalid MOVH of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVW	x_cap+16(FP), R3 // want `invalid MOVW of x_cap\+16\(FP\); slice cap is 8-byte value`
	MOVD	x_cap+16(FP), R3
	MOVD	y+0(FP), R3 // want `invalid offset y\+0\(FP\); expected y\+24\(FP\)`
	MOVD	y_len+8(FP), R3 // want `invalid offset y_len\+8\(FP\); expected y_len\+32\(FP\)`
	MOVD	y_cap+16(FP), R3 // want `invalid offset y_cap\+16\(FP\); expected y_cap\+40\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-32
	MOVH	x+0(FP), R3 // want `invalid MOVH of x\+0\(FP\); interface type is 8-byte value`
	MOVW	x+0(FP), R3 // want `invalid MOVW of x\+0\(FP\); interface type is 8-byte value`
	MOVD	x+0(FP), R3
	MOVH	x_type+0(FP), R3 // want `invalid MOVH of x_type\+0\(FP\); interface type is 8-byte value`
	MOVW	x_type+0(FP), R3 // want `invalid MOVW of x_type\+0\(FP\); interface type is 8-byte value`
	MOVD	x_type+0(FP), R3
	MOVD	x_itable+0(FP), R3 // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVD	x_itable+1(FP), R3 // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), R3 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVW	x_data+0(FP), R3 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVD	x_data+0(FP), R3 // want `invalid offset x_data\+0\(FP\); expected x_data\+8\(FP\)`
	MOVH	x_data+8(FP), R3 // want `invalid MOVH of x_data\+8\(FP\); interface data is 8-byte value`
	MOVW	x_data+8(FP), R3 // want `invalid MOVW of x_data\+8\(FP\); interface data is 8-byte value`
	MOVD	x_data+8(FP), R3
	MOVH	y+16(FP), R3 // want `invalid MOVH of y\+16\(FP\); interface itable is 8-byte value`
	MOVW	y+16(FP), R3 // want `invalid MOVW of y\+16\(FP\); interface itable is 8-byte value`
	MOVD	y+16(FP), R3
	MOVH	y_itable+16(FP), R3 // want `invalid MOVH of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVW	y_itable+16(FP), R3 // want `invalid MOVW of y_itable\+16\(FP\); interface itable is 8-byte value`
	MOVD	y_itable+16(FP), R3
	MOVD	y_type+16(FP), R3 // want `unknown variable y_type; offset 16 is y_itable\+16\(FP\)`
	MOVH	y_data+16(FP), R3 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVW	y_data+16(FP), R3 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVD	y_data+16(FP), R3 // want `invalid offset y_data\+16\(FP\); expected y_data\+24\(FP\)`
	MOVH	y_data+24(FP), R3 // want `invalid MOVH of y_data\+24\(FP\); interface data is 8-byte value`
	MOVW	y_data+24(FP), R3 // want `invalid MOVW of y_data\+24\(FP\); interface data is 8-byte value`
	MOVD	y_data+24(FP), R3
	RET

TEXT ·returnint(SB),0,$0-8
	MOVB	R3, ret+0(FP) // want `invalid MOVB of ret\+0\(FP\); int is 8-byte value`
	MOVH	R3, ret+0(FP) // want `invalid MOVH of ret\+0\(FP\); int is 8-byte value`
	MOVW	R3, ret+0(FP) // want `invalid MOVW of ret\+0\(FP\); int is 8-byte value`
	MOVD	R3, ret+0(FP)
	MOVD	R3, ret+1(FP) // want `invalid offset ret\+1\(FP\); expected ret\+0\(FP\)`
	MOVD	R3, r+0(FP) // want `unknown variable r; offset 0 is ret\+0\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-9
	MOVD	x+0(FP), R3
	MOVB	R3, ret+8(FP)
	MOVH	R3, ret+8(FP) // want `invalid MOVH of ret\+8\(FP\); byte is 1-byte value`
	MOVW	R3, ret+8(FP) // want `invalid MOVW of ret\+8\(FP\); byte is 1-byte value`
	MOVD	R3, ret+8(FP) // want `invalid MOVD of ret\+8\(FP\); byte is 1-byte value`
	MOVB	R3, ret+7(FP) // want `invalid offset ret\+7\(FP\); expected ret\+8\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-41
	MOVB	x+0(FP), R3
	MOVD	R3, r1+8(FP)
	MOVH	R3, r2+16(FP)
	MOVD	R3, r3+24(FP)
	MOVD	R3, r3_base+24(FP)
	MOVD	R3, r3_len+32(FP)
	MOVB	R3, r4+40(FP)
	MOVW	R3, r1+8(FP) // want `invalid MOVW of r1\+8\(FP\); int is 8-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-8
	RET // want `RET without writing to 8-byte ret\+0\(FP\)`

// writing to result in ABIInternal function
TEXT ·returnABIInternal<ABIInternal>(SB), NOSPLIT, $8
	MOVD	$123, R3
	RET
TEXT ·returnmissingABIInternal<ABIInternal>(SB), NOSPLIT, $8
	MOVD	$123, R10
	RET // want `RET without writing to result register`

// issue 69352
TEXT ·returnsyscallABIInternal<ABIInternal>(SB), NOSPLIT, $0
	MOVD	$123, R10
	SYSCALL
	RET


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm8.s
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build mipsle

TEXT ·arg1(SB),0,$0-2
	MOVB	x+0(FP), R1
	MOVBU	y+1(FP), R2
	MOVH	x+0(FP), R1 // want `\[mipsle\] arg1: invalid MOVH of x\+0\(FP\); int8 is 1-byte value`
	MOVHU	y+1(FP), R1 // want `invalid MOVHU of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int8 is 1-byte value`
	MOVWU	y+1(FP), R1 // want `invalid MOVWU of y\+1\(FP\); uint8 is 1-byte value`
	MOVW	y+1(FP), R1 // want `invalid MOVW of y\+1\(FP\); uint8 is 1-byte value`
	MOVB	x+1(FP), R1 // want `invalid offset x\+1\(FP\); expected x\+0\(FP\)`
	MOVBU	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+1\(FP\)`
	MOVB	8(R29), R1 // want `8\(R29\) should be x\+0\(FP\)`
	MOVB	9(R29), R1 // want `9\(R29\) should be y\+1\(FP\)`
	MOVB	10(R29), R1 // want `use of 10\(R29\) points beyond argument frame`
	RET

TEXT ·arg2(SB),0,$0-4
	MOVBU	x+0(FP), R1 // want `arg2: invalid MOVBU of x\+0\(FP\); int16 is 2-byte value`
	MOVB	y+2(FP), R1 // want `invalid MOVB of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+0(FP), R1
	MOVH	y+2(FP), R2
	MOVWU	x+0(FP), R1 // want `invalid MOVWU of x\+0\(FP\); int16 is 2-byte value`
	MOVW	y+2(FP), R1 // want `invalid MOVW of y\+2\(FP\); uint16 is 2-byte value`
	MOVHU	x+2(FP), R1 // want `invalid offset x\+2\(FP\); expected x\+0\(FP\)`
	MOVH	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+2\(FP\)`
	RET

TEXT ·arg4(SB),0,$0-2 // want `arg4: wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int32 is 4-byte value`
	MOVB	y+4(FP), R2 // want `invalid MOVB of y\+4\(FP\); uint32 is 4-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int32 is 4-byte value`
	MOVH	y+4(FP), R1 // want `invalid MOVH of y\+4\(FP\); uint32 is 4-byte value`
	MOVW	x+0(FP), R1
	MOVW	y+4(FP), R1
	MOVW	x+4(FP), R1 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·arg8(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-16`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int64 is 8-byte value`
	MOVB	y+8(FP), R2 // want `invalid MOVB of y\+8\(FP\); uint64 is 8-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int64 is 8-byte value`
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); uint64 is 8-byte value`
	MOVW	x+0(FP), R1 // want `invalid MOVW of x\+0\(FP\); int64 is 8-byte value containing x_lo\+0\(FP\) and x_hi\+4\(FP\)`
	MOVW	$x+0(FP), R1 // ok
	MOVW	x_lo+0(FP), R1
	MOVW	x_hi+4(FP), R1
	MOVW	y+8(FP), R1 // want `invalid MOVW of y\+8\(FP\); uint64 is 8-byte value containing y_lo\+8\(FP\) and y_hi\+12\(FP\)`
	MOVW	y_lo+8(FP),  R1
	MOVW	y_hi+12(FP), R1
	RET

TEXT ·argint(SB),0,$0-2 // want `wrong argument size 2; expected \$\.\.\.-8`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); int is 4-byte value`
	MOVB	y+4(FP), R2 // want `invalid MOVB of y\+4\(FP\); uint is 4-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); int is 4-byte value`
	MOVH	y+4(FP), R1 // want `invalid MOVH of y\+4\(FP\); uint is 4-byte value`
	MOVW	x+0(FP), R1
	MOVW	y+4(FP), R1
	MOVW	x+4(FP), R1 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	RET

TEXT ·argptr(SB),7,$0-2 // want `wrong argument size 2; expected \$\.\.\.-20`
	MOVB	x+0(FP), R1 // want `invalid MOVB of x\+0\(FP\); \*byte is 4-byte value`
	MOVB	y+4(FP), R2 // want `invalid MOVB of y\+4\(FP\); \*byte is 4-byte value`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); \*byte is 4-byte value`
	MOVH	y+4(FP), R1 // want `invalid MOVH of y\+4\(FP\); \*byte is 4-byte value`
	MOVW	x+0(FP), R1
	MOVW	y+4(FP), R1
	MOVW	x+4(FP), R1 // want `invalid offset x\+4\(FP\); expected x\+0\(FP\)`
	MOVW	y+2(FP), R1 // want `invalid offset y\+2\(FP\); expected y\+4\(FP\)`
	MOVH	c+8(FP), R1 // want `invalid MOVH of c\+8\(FP\); chan int is 4-byte value`
	MOVH	m+12(FP), R1 // want `invalid MOVH of m\+12\(FP\); map\[int\]int is 4-byte value`
	MOVH	f+16(FP), R1 // want `invalid MOVH of f\+16\(FP\); func\(\) is 4-byte value`
	RET

TEXT ·argstring(SB),0,$16 // want `wrong argument size 0; expected \$\.\.\.-16`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); string base is 4-byte value`
	MOVW	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); string base is 4-byte value`
	MOVW	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVH	x_len+4(FP), R1 // want `invalid MOVH of x_len\+4\(FP\); string len is 4-byte value`
	MOVW	x_len+4(FP), R1
	MOVW	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+8\(FP\)`
	MOVW	y_len+4(FP), R1 // want `invalid offset y_len\+4\(FP\); expected y_len\+12\(FP\)`
	RET

TEXT ·argslice(SB),0,$24 // want `wrong argument size 0; expected \$\.\.\.-24`
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); slice base is 4-byte value`
	MOVW	x+0(FP), R1
	MOVH	x_base+0(FP), R1 // want `invalid MOVH of x_base\+0\(FP\); slice base is 4-byte value`
	MOVW	x_base+0(FP), R1
	MOVH	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVW	x_len+0(FP), R1 // want `invalid offset x_len\+0\(FP\); expected x_len\+4\(FP\)`
	MOVH	x_len+4(FP), R1 // want `invalid MOVH of x_len\+4\(FP\); slice len is 4-byte value`
	MOVW	x_len+4(FP), R1
	MOVH	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVW	x_cap+0(FP), R1 // want `invalid offset x_cap\+0\(FP\); expected x_cap\+8\(FP\)`
	MOVH	x_cap+8(FP), R1 // want `invalid MOVH of x_cap\+8\(FP\); slice cap is 4-byte value`
	MOVW	x_cap+8(FP), R1
	MOVW	y+0(FP), R1 // want `invalid offset y\+0\(FP\); expected y\+12\(FP\)`
	MOVW	y_len+4(FP), R1 // want `invalid offset y_len\+4\(FP\); expected y_len\+16\(FP\)`
	MOVW	y_cap+8(FP), R1 // want `invalid offset y_cap\+8\(FP\); expected y_cap\+20\(FP\)`
	RET

TEXT ·argiface(SB),0,$0-16
	MOVH	x+0(FP), R1 // want `invalid MOVH of x\+0\(FP\); interface type is 4-byte value`
	MOVW	x+0(FP), R1
	MOVH	x_type+0(FP), R1 // want `invalid MOVH of x_type\+0\(FP\); interface type is 4-byte value`
	MOVW	x_type+0(FP), R1
	MOVQ	x_itable+0(FP), R1 // want `unknown variable x_itable; offset 0 is x_type\+0\(FP\)`
	MOVQ	x_itable+1(FP), R1 // want `unknown variable x_itable; offset 1 is x_type\+0\(FP\)`
	MOVH	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVW	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVQ	x_data+0(FP), R1 // want `invalid offset x_data\+0\(FP\); expected x_data\+4\(FP\)`
	MOVH	x_data+4(FP), R1 // want `invalid MOVH of x_data\+4\(FP\); interface data is 4-byte value`
	MOVW	x_data+4(FP), R1
	MOVH	y+8(FP), R1 // want `invalid MOVH of y\+8\(FP\); interface itable is 4-byte value`
	MOVW	y+8(FP), R1
	MOVH	y_itable+8(FP), R1 // want `invalid MOVH of y_itable\+8\(FP\); interface itable is 4-byte value`
	MOVW	y_itable+8(FP), R1
	MOVW	y_type+8(FP), AX // want `unknown variable y_type; offset 8 is y_itable\+8\(FP\)`
	MOVH	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVW	y_data+8(FP), AX // want `invalid offset y_data\+8\(FP\); expected y_data\+12\(FP\)`
	MOVH	y_data+12(FP), AX // want `invalid MOVH of y_data\+12\(FP\); interface data is 4-byte value`
	MOVW	y_data+12(FP), AX
	RET

TEXT ·returnbyte(SB),0,$0-5
	MOVW	x+0(FP), R1
	MOVB	R1, ret+4(FP)
	MOVH	R1, ret+4(FP) // want `invalid MOVH of ret\+4\(FP\); byte is 1-byte value`
	MOVW	R1, ret+4(FP) // want `invalid MOVW of ret\+4\(FP\); byte is 1-byte value`
	MOVB	R1, ret+3(FP) // want `invalid offset ret\+3\(FP\); expected ret\+4\(FP\)`
	RET

TEXT ·returnbyte(SB),0,$0-5
	MOVW	x+0(FP), R1
	MOVB	R1, ret+4(FP)
	MOVH	R1, ret+4(FP) // want `invalid MOVH of ret\+4\(FP\); byte is 1-byte value`
	MOVW	R1, ret+4(FP) // want `invalid MOVW of ret\+4\(FP\); byte is 1-byte value`
	MOVB	R1, ret+3(FP) // want `invalid offset ret\+3\(FP\); expected ret\+4\(FP\)`
	RET

TEXT ·returnnamed(SB),0,$0-21
	MOVB	x+0(FP), AX
	MOVW	R1, r1+4(FP)
	MOVH	R1, r2+8(FP)
	MOVW	R1, r3+12(FP)
	MOVW	R1, r3_base+12(FP)
	MOVW	R1, r3_len+16(FP)
	MOVB	R1, r4+20(FP)
	MOVB	R1, r1+4(FP) // want `invalid MOVB of r1\+4\(FP\); int is 4-byte value`
	RET

TEXT ·returnintmissing(SB),0,$0-4
	RET // want `RET without writing to 4-byte ret\+0\(FP\)`


================================================
FILE: go/analysis/passes/asmdecl/testdata/src/a/asm9.s
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build wasm

TEXT ·returnint(SB),NOSPLIT|NOFRAME,$0-8
	MOVD	24(SP), R1 // ok to access beyond stack frame with NOFRAME
	CallImport // interpreted as writing result
	RET

TEXT ·returnbyte(SB),$0-9
	RET // want `RET without writing`


================================================
FILE: go/analysis/passes/assign/assign.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package assign

// TODO(adonovan): check also for assignments to struct fields inside
// methods that are on T instead of *T.

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"
	"reflect"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "assign",
	Doc:      analyzerutil.MustExtractDoc(doc, "assign"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/assign",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info    = pass.TypesInfo
	)

	for curAssign := range inspect.Root().Preorder((*ast.AssignStmt)(nil)) {
		stmt := curAssign.Node().(*ast.AssignStmt)
		if stmt.Tok != token.ASSIGN {
			continue // ignore :=
		}
		if len(stmt.Lhs) != len(stmt.Rhs) {
			// If LHS and RHS have different cardinality, they can't be the same.
			continue
		}

		// Delete redundant LHS, RHS pairs, taking care
		// to include intervening commas.
		var (
			exprs                    []string // expressions appearing on both sides (x = x)
			edits                    []analysis.TextEdit
			runStartLHS, runStartRHS token.Pos // non-zero => within a run
		)
		for i, lhs := range stmt.Lhs {
			rhs := stmt.Rhs[i]
			isSelfAssign := false
			var le string

			if typesinternal.NoEffects(info, lhs) &&
				typesinternal.NoEffects(info, rhs) &&
				!isMapIndex(info, lhs) &&
				reflect.TypeOf(lhs) == reflect.TypeOf(rhs) { // short-circuit the heavy-weight gofmt check

				le = astutil.Format(pass.Fset, lhs)
				re := astutil.Format(pass.Fset, rhs)
				if le == re {
					isSelfAssign = true
				}
			}

			if isSelfAssign {
				exprs = append(exprs, le)
				if !runStartLHS.IsValid() {
					// Start of a new run of self-assignments.
					if i > 0 {
						runStartLHS = stmt.Lhs[i-1].End()
						runStartRHS = stmt.Rhs[i-1].End()
					} else {
						runStartLHS = lhs.Pos()
						runStartRHS = rhs.Pos()
					}
				}
			} else if runStartLHS.IsValid() {
				// End of a run of self-assignments.
				endLHS, endRHS := stmt.Lhs[i-1].End(), stmt.Rhs[i-1].End()
				if runStartLHS == stmt.Lhs[0].Pos() {
					endLHS, endRHS = lhs.Pos(), rhs.Pos()
				}
				edits = append(edits,
					analysis.TextEdit{Pos: runStartLHS, End: endLHS},
					analysis.TextEdit{Pos: runStartRHS, End: endRHS},
				)
				runStartLHS, runStartRHS = 0, 0
			}
		}

		// If a run of self-assignments continues to the end of the statement, close it.
		if runStartLHS.IsValid() {
			last := len(stmt.Lhs) - 1
			edits = append(edits,
				analysis.TextEdit{Pos: runStartLHS, End: stmt.Lhs[last].End()},
				analysis.TextEdit{Pos: runStartRHS, End: stmt.Rhs[last].End()},
			)
		}

		if len(exprs) == 0 {
			continue
		}

		if len(exprs) == len(stmt.Lhs) {
			// If every part of the statement is a self-assignment,
			// remove the whole statement.
			tokFile := pass.Fset.File(stmt.Pos())
			edits = refactor.DeleteStmt(tokFile, curAssign)
		}

		pass.Report(analysis.Diagnostic{
			Pos:     stmt.Pos(),
			Message: "self-assignment of " + strings.Join(exprs, ", "),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   "Remove self-assignment",
				TextEdits: edits,
			}},
		})
	}

	return nil, nil
}

// isMapIndex returns true if e is a map index expression.
func isMapIndex(info *types.Info, e ast.Expr) bool {
	if idx, ok := ast.Unparen(e).(*ast.IndexExpr); ok {
		if typ := info.Types[idx.X].Type; typ != nil {
			_, ok := typ.Underlying().(*types.Map)
			return ok
		}
	}
	return false
}


================================================
FILE: go/analysis/passes/assign/assign_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package assign_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/assign"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, assign.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/assign/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package assign defines an Analyzer that detects useless assignments.
//
// # Analyzer assign
//
// assign: check for useless assignments
//
// This checker reports assignments of the form x = x or a[i] = a[i].
// These are almost always useless, and even when they aren't they are
// usually a mistake.
package assign


================================================
FILE: go/analysis/passes/assign/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the useless-assignment checker.

package testdata

import "math/rand"

type ST struct {
	x int
	l []int
}

func (s *ST) SetX(x int, ch chan int) {
	// Accidental self-assignment; it should be "s.x = x"
	x = x // want "self-assignment of x"
	// Another mistake
	s.x = s.x // want "self-assignment of s.x"

	s.l[0] = s.l[0] // want "self-assignment of s.l.0."

	// Report self-assignment to x but preserve the actual assignment to s.x
	x, s.x = x, 1 // want "self-assignment of x"
	s.x, x = 1, x // want "self-assignment of x"

	// Delete multiple self-assignment
	x, s.x = x, s.x                       // want "self-assignment of x, s.x"
	s.l[0], x, s.x = 1, x, s.x            // want "self-assignment of x, s.x"
	x, s.l[0], s.x = x, 1, s.x            // want "self-assignment of x, s.x"
	x, s.x, s.l[0] = x, s.x, 1            // want "self-assignment of x, s.x"
	s.l[0], x, s.x, s.l[1] = 1, x, s.x, 1 // want "self-assignment of x, s.x"
	x, s.l[0], s.l[1], s.x = x, 1, 1, s.x // want "self-assignment of x, s.x"

	// Bail on any potential side effects to avoid false positives
	s.l[num()] = s.l[num()]
	rng := rand.New(rand.NewSource(0))
	s.l[rng.Intn(len(s.l))] = s.l[rng.Intn(len(s.l))]
	s.l[<-ch] = s.l[<-ch]
}

func num() int { return 2 }

func Index() {
	s := []int{1}
	s[0] = s[0] // want "self-assignment"

	var a [5]int
	a[0] = a[0] // want "self-assignment"

	pa := &[2]int{1, 2}
	pa[1] = pa[1] // want "self-assignment"

	var pss *struct { // report self assignment despite nil dereference
		s []int
	}
	pss.s[0] = pss.s[0] // want "self-assignment"

	m := map[int]string{1: "a"}
	m[0] = m[0]     // bail on map self-assignments due to side effects
	m[1] = m[1]     // not modeling what elements must be in the map
	(m[2]) = (m[2]) // even with parens
	type Map map[string]bool
	named := make(Map)
	named["s"] = named["s"] // even on named maps.
	var psm *struct {
		m map[string]int
	}
	psm.m["key"] = psm.m["key"] // handles dereferences
}


================================================
FILE: go/analysis/passes/assign/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the useless-assignment checker.

package testdata

import "math/rand"

type ST struct {
	x int
	l []int
}

func (s *ST) SetX(x int, ch chan int) {
	// Accidental self-assignment; it should be "s.x = x"
	// Another mistake

	// Report self-assignment to x but preserve the actual assignment to s.x
	s.x = 1 // want "self-assignment of x"
	s.x = 1 // want "self-assignment of x"

	// Delete multiple self-assignment
	s.l[0] = 1            // want "self-assignment of x, s.x"
	s.l[0] = 1            // want "self-assignment of x, s.x"
	s.l[0] = 1            // want "self-assignment of x, s.x"
	s.l[0], s.l[1] = 1, 1 // want "self-assignment of x, s.x"
	s.l[0], s.l[1] = 1, 1 // want "self-assignment of x, s.x"

	// Bail on any potential side effects to avoid false positives
	s.l[num()] = s.l[num()]
	rng := rand.New(rand.NewSource(0))
	s.l[rng.Intn(len(s.l))] = s.l[rng.Intn(len(s.l))]
	s.l[<-ch] = s.l[<-ch]
}

func num() int { return 2 }

func Index() {
	s := []int{1}

	var a [5]int

	pa := &[2]int{1, 2}

	var pss *struct { // report self assignment despite nil dereference
		s []int
	}

	m := map[int]string{1: "a"}
	m[0] = m[0]     // bail on map self-assignments due to side effects
	m[1] = m[1]     // not modeling what elements must be in the map
	(m[2]) = (m[2]) // even with parens
	type Map map[string]bool
	named := make(Map)
	named["s"] = named["s"] // even on named maps.
	var psm *struct {
		m map[string]int
	}
	psm.m["key"] = psm.m["key"] // handles dereferences
}


================================================
FILE: go/analysis/passes/assign/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the useless-assignment checker.

package testdata

import "math/rand"

type ST[T interface{ ~int }] struct {
	x T
	l []T
}

func (s *ST[T]) SetX(x T, ch chan T) {
	// Accidental self-assignment; it should be "s.x = x"
	x = x // want "self-assignment of x"
	// Another mistake
	s.x = s.x // want "self-assignment of s.x"

	s.l[0] = s.l[0] // want "self-assignment of s.l.0."

	// Bail on any potential side effects to avoid false positives
	s.l[num()] = s.l[num()]
	rng := rand.New(rand.NewSource(0))
	s.l[rng.Intn(len(s.l))] = s.l[rng.Intn(len(s.l))]
	s.l[<-ch] = s.l[<-ch]
}

func num() int { return 2 }


================================================
FILE: go/analysis/passes/assign/testdata/src/typeparams/typeparams.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the useless-assignment checker.

package testdata

import "math/rand"

type ST[T interface{ ~int }] struct {
	x T
	l []T
}

func (s *ST[T]) SetX(x T, ch chan T) {
	// Accidental self-assignment; it should be "s.x = x"
	// Another mistake


	// Bail on any potential side effects to avoid false positives
	s.l[num()] = s.l[num()]
	rng := rand.New(rand.NewSource(0))
	s.l[rng.Intn(len(s.l))] = s.l[rng.Intn(len(s.l))]
	s.l[<-ch] = s.l[<-ch]
}

func num() int { return 2 }


================================================
FILE: go/analysis/passes/atomic/atomic.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package atomic

import (
	_ "embed"
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "atomic",
	Doc:              analyzerutil.MustExtractDoc(doc, "atomic"),
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomic",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "sync/atomic") {
		return nil, nil // doesn't directly import sync/atomic
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.AssignStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		n := node.(*ast.AssignStmt)
		if len(n.Lhs) != len(n.Rhs) {
			return
		}
		if len(n.Lhs) == 1 && n.Tok == token.DEFINE {
			return
		}

		for i, right := range n.Rhs {
			call, ok := right.(*ast.CallExpr)
			if !ok {
				continue
			}
			obj := typeutil.Callee(pass.TypesInfo, call)
			if typesinternal.IsFunctionNamed(obj, "sync/atomic", "AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr") {
				checkAtomicAddAssignment(pass, n.Lhs[i], call)
			}
		}
	})
	return nil, nil
}

// checkAtomicAddAssignment walks the atomic.Add* method calls checking
// for assigning the return value to the same variable being used in the
// operation
func checkAtomicAddAssignment(pass *analysis.Pass, left ast.Expr, call *ast.CallExpr) {
	if len(call.Args) != 2 {
		return
	}
	arg := call.Args[0]
	broken := false

	gofmt := func(e ast.Expr) string { return astutil.Format(pass.Fset, e) }

	if uarg, ok := arg.(*ast.UnaryExpr); ok && uarg.Op == token.AND {
		broken = gofmt(left) == gofmt(uarg.X)
	} else if star, ok := left.(*ast.StarExpr); ok {
		broken = gofmt(star.X) == gofmt(arg)
	}

	if broken {
		pass.ReportRangef(left, "direct assignment to atomic value")
	}
}


================================================
FILE: go/analysis/passes/atomic/atomic_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package atomic_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/atomic"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, atomic.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/atomic/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package atomic defines an Analyzer that checks for common mistakes
// using the sync/atomic package.
//
// # Analyzer atomic
//
// atomic: check for common mistakes using the sync/atomic package
//
// The atomic checker looks for assignment statements of the form:
//
//	x = atomic.AddUint64(&x, 1)
//
// which are not atomic.
package atomic


================================================
FILE: go/analysis/passes/atomic/testdata/src/a/a.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the atomic checker.

package a

import (
	"sync/atomic"
)

type Counter uint64

func AtomicTests() {
	x := uint64(1)
	x = atomic.AddUint64(&x, 1)          // want "direct assignment to atomic value"
	_, x = 10, atomic.AddUint64(&x, 1)   // want "direct assignment to atomic value"
	x, _ = atomic.AddUint64(&x, 1), 10   // want "direct assignment to atomic value"
	x, _ = (atomic.AddUint64)(&x, 1), 10 // want "direct assignment to atomic value"

	y := &x
	*y = atomic.AddUint64(y, 1) // want "direct assignment to atomic value"

	var su struct{ Counter uint64 }
	su.Counter = atomic.AddUint64(&su.Counter, 1) // want "direct assignment to atomic value"
	z1 := atomic.AddUint64(&su.Counter, 1)
	_ = z1 // Avoid err "z declared and not used"

	var sp struct{ Counter *uint64 }
	*sp.Counter = atomic.AddUint64(sp.Counter, 1) // want "direct assignment to atomic value"
	z2 := atomic.AddUint64(sp.Counter, 1)
	_ = z2 // Avoid err "z declared and not used"

	au := []uint64{10, 20}
	au[0] = atomic.AddUint64(&au[0], 1) // want "direct assignment to atomic value"
	au[1] = atomic.AddUint64(&au[0], 1)

	ap := []*uint64{&au[0], &au[1]}
	*ap[0] = atomic.AddUint64(ap[0], 1) // want "direct assignment to atomic value"
	*ap[1] = atomic.AddUint64(ap[0], 1)

	x = atomic.AddUint64() // Used to make vet crash; now silently ignored.

	{
		// A variable declaration creates a new variable in the current scope.
		x := atomic.AddUint64(&x, 1)

		// Re-declaration assigns a new value.
		x, w := atomic.AddUint64(&x, 1), 10 // want "direct assignment to atomic value"
		_ = w
	}
}

type T struct{}

func (T) AddUint64(addr *uint64, delta uint64) uint64 { return 0 }

func NonAtomic() {
	x := uint64(1)
	var atomic T
	x = atomic.AddUint64(&x, 1) // ok; not the imported pkg
}


================================================
FILE: go/analysis/passes/atomic/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the atomic checker.

package a

import (
	"sync/atomic"
)

type Subtractable interface {
	~int64
}

func Sub[T Subtractable](addr *T, delta T) T {
	// the followings result in type errors, but doesn't stop this vet check
	*addr = atomic.AddInt64(addr, -delta)  // want "direct assignment to atomic value"
	*addr = atomic.AddUintptr(addr, delta) // want "direct assignment to atomic value"
	atomic.AddInt64()  // vet ignores it
	return *addr
}

type _S[T Subtractable] struct {
	x *T
}

func (v _S) AddInt64(_ *int64, delta int64) int64 {
	*v.x = atomic.AddInt64(v.x, delta)  // want "direct assignment to atomic value"
	return *v.x
}

func NonAtomicInt64() {
	var atomic _S[int64]
	*atomic.x = atomic.AddInt64(atomic.x, 123)  // ok; AddInt64 is not sync/atomic.AddInt64.
}

================================================
FILE: go/analysis/passes/atomicalign/atomicalign.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package atomicalign defines an Analyzer that checks for non-64-bit-aligned
// arguments to sync/atomic functions. On non-32-bit platforms, those functions
// panic if their argument variables are not 64-bit aligned. It is therefore
// the caller's responsibility to arrange for 64-bit alignment of such variables.
// See https://golang.org/pkg/sync/atomic/#pkg-note-BUG
package atomicalign

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = "check for non-64-bits-aligned arguments to sync/atomic functions"

var Analyzer = &analysis.Analyzer{
	Name:     "atomicalign",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomicalign",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if 8*pass.TypesSizes.Sizeof(types.Typ[types.Uintptr]) == 64 {
		return nil, nil // 64-bit platform
	}
	if !typesinternal.Imports(pass.Pkg, "sync/atomic") {
		return nil, nil // doesn't directly import sync/atomic
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	funcNames := []string{
		"AddInt64", "AddUint64",
		"LoadInt64", "LoadUint64",
		"StoreInt64", "StoreUint64",
		"SwapInt64", "SwapUint64",
		"CompareAndSwapInt64", "CompareAndSwapUint64",
	}

	inspect.Preorder(nodeFilter, func(node ast.Node) {
		call := node.(*ast.CallExpr)
		obj := typeutil.Callee(pass.TypesInfo, call)
		if typesinternal.IsFunctionNamed(obj, "sync/atomic", funcNames...) {
			// For all the listed functions, the expression to check is always the first function argument.
			check64BitAlignment(pass, obj.Name(), call.Args[0])
		}
	})

	return nil, nil
}

func check64BitAlignment(pass *analysis.Pass, funcName string, arg ast.Expr) {
	// Checks the argument is made of the address operator (&) applied to
	// a struct field (as opposed to a variable as the first word of
	// uint64 and int64 variables can be relied upon to be 64-bit aligned).
	unary, ok := arg.(*ast.UnaryExpr)
	if !ok || unary.Op != token.AND {
		return
	}

	// Retrieve the types.Struct in order to get the offset of the
	// atomically accessed field.
	sel, ok := unary.X.(*ast.SelectorExpr)
	if !ok {
		return
	}
	tvar, ok := pass.TypesInfo.Selections[sel].Obj().(*types.Var)
	if !ok || !tvar.IsField() {
		return
	}

	stype, ok := pass.TypesInfo.Types[sel.X].Type.Underlying().(*types.Struct)
	if !ok {
		return
	}

	var offset int64
	var fields []*types.Var
	for i := 0; i < stype.NumFields(); i++ {
		f := stype.Field(i)
		fields = append(fields, f)
		if f == tvar {
			// We're done, this is the field we were looking for,
			// no need to fill the fields slice further.
			offset = pass.TypesSizes.Offsetsof(fields)[i]
			break
		}
	}
	if offset&7 == 0 {
		return // 64-bit aligned
	}

	pass.ReportRangef(arg, "address of non 64-bit aligned field .%s passed to atomic.%s", tvar.Name(), funcName)
}


================================================
FILE: go/analysis/passes/atomicalign/atomicalign_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package atomicalign_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/atomicalign"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, atomicalign.Analyzer, "a", "b")
}


================================================
FILE: go/analysis/passes/atomicalign/testdata/src/a/a.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the atomic alignment checker.

//go:build arm || 386
// +build arm 386

package testdata

import (
	"io"
	"sync/atomic"
)

func intsAlignment() {
	var s struct {
		a bool
		b uint8
		c int8
		d byte
		f int16
		g int16
		h int64
		i byte
		j uint64
	}
	atomic.AddInt64(&s.h, 9)
	atomic.AddUint64(&s.j, 0) // want "address of non 64-bit aligned field .j passed to atomic.AddUint64"
}

func floatAlignment() {
	var s struct {
		a float32
		b int64
		c float32
		d float64
		e uint64
	}
	atomic.LoadInt64(&s.b) // want "address of non 64-bit aligned field .b passed to atomic.LoadInt64"
	atomic.LoadUint64(&s.e)
}

func uintptrAlignment() {
	var s struct {
		a uintptr
		b int64
		c int
		d uint
		e int32
		f uint64
	}
	atomic.StoreInt64(&s.b, 0) // want "address of non 64-bit aligned field .b passed to atomic.StoreInt64"
	atomic.StoreUint64(&s.f, 0)
}

func runeAlignment() {
	var s struct {
		a rune
		b int64
		_ rune
		c uint64
	}
	atomic.SwapInt64(&s.b, 0) // want "address of non 64-bit aligned field .b passed to atomic.SwapInt64"
	atomic.SwapUint64(&s.c, 0)
}

func complexAlignment() {
	var s struct {
		a complex64
		b int64
		c complex128
		d uint64
	}
	atomic.CompareAndSwapInt64(&s.b, 0, 1)
	atomic.CompareAndSwapUint64(&s.d, 0, 1)
}

// continuer ici avec les tests

func channelAlignment() {
	var a struct {
		a chan struct{}
		b int64
		c <-chan struct{}
		d uint64
	}

	atomic.AddInt64(&a.b, 0) // want "address of non 64-bit aligned field .b passed to atomic.AddInt64"
	atomic.AddUint64(&a.d, 0)
}

func arrayAlignment() {
	var a struct {
		a [1]uint16
		b int64
		_ [2]uint16
		c int64
		d [1]uint16
		e uint64
	}

	atomic.LoadInt64(&a.b) // want "address of non 64-bit aligned field .b passed to atomic.LoadInt64"
	atomic.LoadInt64(&a.c)
	atomic.LoadUint64(&a.e)   // want "address of non 64-bit aligned field .e passed to atomic.LoadUint64"
	(atomic.LoadUint64)(&a.e) // want "address of non 64-bit aligned field .e passed to atomic.LoadUint64"
}

func anonymousFieldAlignment() {
	var f struct {
		a, b int32
		c, d int64
		_    bool
		e, f uint64
	}

	atomic.StoreInt64(&f.c, 12)
	atomic.StoreInt64(&f.d, 27)
	atomic.StoreUint64(&f.e, 6)  // want "address of non 64-bit aligned field .e passed to atomic.StoreUint64"
	atomic.StoreUint64(&f.f, 79) // want "address of non 64-bit aligned field .f passed to atomic.StoreUint64"
}

type ts struct {
	e  int64
	e2 []int
	f  uint64
}

func typedStructAlignment() {
	var b ts
	atomic.SwapInt64(&b.e, 9)
	atomic.SwapUint64(&b.f, 9) // want "address of non 64-bit aligned field .f passed to atomic.SwapUint64"
}

func aliasAlignment() {
	type (
		mybytea uint8
		mybyteb byte
		mybytec = uint8
		mybyted = byte
	)

	var e struct {
		a    byte
		b    mybytea
		c    mybyteb
		e    mybytec
		f    int64
		g, h uint16
		i    uint64
	}

	atomic.CompareAndSwapInt64(&e.f, 0, 1) // want "address of non 64-bit aligned field .f passed to atomic.CompareAndSwapInt64"
	atomic.CompareAndSwapUint64(&e.i, 1, 2)
}

func stringAlignment() {
	var a struct {
		a uint32
		b string
		c int64
	}
	atomic.AddInt64(&a.c, 10) // want "address of non 64-bit aligned field .c passed to atomic.AddInt64"
}

func sliceAlignment() {
	var s struct {
		a []int32
		b int64
		c uint32
		d uint64
	}

	atomic.LoadInt64(&s.b) // want "address of non 64-bit aligned field .b passed to atomic.LoadInt64"
	atomic.LoadUint64(&s.d)
}

func interfaceAlignment() {
	var s struct {
		a interface{}
		b int64
		c io.Writer
		e int64
		_ int32
		f uint64
	}

	atomic.StoreInt64(&s.b, 9)
	atomic.StoreInt64(&s.e, 9)
	atomic.StoreUint64(&s.f, 9) // want "address of non 64-bit aligned field .f passed to atomic.StoreUint64"
}

func pointerAlignment() {
	var s struct {
		a, b *int
		c    int64
		d    *interface{}
		e    uint64
	}

	atomic.SwapInt64(&s.c, 9)
	atomic.SwapUint64(&s.e, 9) // want "address of non 64-bit aligned field .e passed to atomic.SwapUint64"
}

// non-struct fields are already 64-bits correctly aligned per Go spec
func nonStructFields() {
	var (
		a *int64
		b [2]uint64
		c int64
	)

	atomic.CompareAndSwapInt64(a, 10, 11)
	atomic.CompareAndSwapUint64(&b[0], 5, 23)
	atomic.CompareAndSwapInt64(&c, -1, -15)
}

func embeddedStructFields() {
	var s1 struct {
		_ struct{ _ int32 }
		a int64
		_ struct{}
		b uint64
		_ struct{ _ [2]uint16 }
		c int64
	}

	atomic.AddInt64(&s1.a, 9)  // want "address of non 64-bit aligned field .a passed to atomic.AddInt64"
	atomic.AddUint64(&s1.b, 9) // want "address of non 64-bit aligned field .b passed to atomic.AddUint64"
	atomic.AddInt64(&s1.c, 9)
}


================================================
FILE: go/analysis/passes/atomicalign/testdata/src/a/stub.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is only here to not trigger "build constraints exclude all Go files" during tests

package testdata


================================================
FILE: go/analysis/passes/atomicalign/testdata/src/b/b.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build !arm,!386

package testdata

import (
	"sync/atomic"
)

func nonAffectedArchs() {
	var s struct {
		_ bool
		a uint64
	}
	atomic.SwapUint64(&s.a, 9) // ok on 64-bit architectures
}


================================================
FILE: go/analysis/passes/atomicalign/testdata/src/b/stub.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is only here to not trigger "build constraints exclude all Go files" during tests

package testdata


================================================
FILE: go/analysis/passes/bools/bools.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package bools defines an Analyzer that detects common mistakes
// involving boolean operators.
package bools

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = "check for common mistakes involving boolean operators"

var Analyzer = &analysis.Analyzer{
	Name:     "bools",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/bools",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.BinaryExpr)(nil),
	}
	seen := make(map[*ast.BinaryExpr]bool)
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		e := n.(*ast.BinaryExpr)
		if seen[e] {
			// Already processed as a subexpression of an earlier node.
			return
		}

		var op boolOp
		switch e.Op {
		case token.LOR:
			op = or
		case token.LAND:
			op = and
		default:
			return
		}

		comm := op.commutativeSets(pass.TypesInfo, e, seen)
		for _, exprs := range comm {
			op.checkRedundant(pass, exprs)
			op.checkSuspect(pass, exprs)
		}
	})
	return nil, nil
}

type boolOp struct {
	name  string
	tok   token.Token // token corresponding to this operator
	badEq token.Token // token corresponding to the equality test that should not be used with this operator
}

var (
	or  = boolOp{"or", token.LOR, token.NEQ}
	and = boolOp{"and", token.LAND, token.EQL}
)

// commutativeSets returns all side effect free sets of
// expressions in e that are connected by op.
// For example, given 'a || b || f() || c || d' with the or op,
// commutativeSets returns {{b, a}, {d, c}}.
// commutativeSets adds any expanded BinaryExprs to seen.
func (op boolOp) commutativeSets(info *types.Info, e *ast.BinaryExpr, seen map[*ast.BinaryExpr]bool) [][]ast.Expr {
	exprs := op.split(e, seen)

	// Partition the slice of expressions into commutative sets.
	i := 0
	var sets [][]ast.Expr
	for j := 0; j <= len(exprs); j++ {
		if j == len(exprs) || !typesinternal.NoEffects(info, exprs[j]) {
			if i < j {
				sets = append(sets, exprs[i:j])
			}
			i = j + 1
		}
	}

	return sets
}

// checkRedundant checks for expressions of the form
//
//	e && e
//	e || e
//
// Exprs must contain only side effect free expressions.
func (op boolOp) checkRedundant(pass *analysis.Pass, exprs []ast.Expr) {
	seen := make(map[string]bool)
	for _, e := range exprs {
		efmt := astutil.Format(pass.Fset, e)
		if seen[efmt] {
			pass.ReportRangef(e, "redundant %s: %s %s %s", op.name, efmt, op.tok, efmt)
		} else {
			seen[efmt] = true
		}
	}
}

// checkSuspect checks for expressions of the form
//
//	x != c1 || x != c2
//	x == c1 && x == c2
//
// where c1 and c2 are constant expressions.
// If c1 and c2 are the same then it's redundant;
// if c1 and c2 are different then it's always true or always false.
// Exprs must contain only side effect free expressions.
func (op boolOp) checkSuspect(pass *analysis.Pass, exprs []ast.Expr) {
	// seen maps from expressions 'x' to equality expressions 'x != c'.
	seen := make(map[string]string)

	for _, e := range exprs {
		bin, ok := e.(*ast.BinaryExpr)
		if !ok || bin.Op != op.badEq {
			continue
		}

		// In order to avoid false positives, restrict to cases
		// in which one of the operands is constant. We're then
		// interested in the other operand.
		// In the rare case in which both operands are constant
		// (e.g. runtime.GOOS and "windows"), we'll only catch
		// mistakes if the LHS is repeated, which is how most
		// code is written.
		var x ast.Expr
		switch {
		case pass.TypesInfo.Types[bin.Y].Value != nil:
			x = bin.X
		case pass.TypesInfo.Types[bin.X].Value != nil:
			x = bin.Y
		default:
			continue
		}

		// e is of the form 'x != c' or 'x == c'.
		xfmt := astutil.Format(pass.Fset, x)
		efmt := astutil.Format(pass.Fset, e)
		if prev, found := seen[xfmt]; found {
			// checkRedundant handles the case in which efmt == prev.
			if efmt != prev {
				pass.ReportRangef(e, "suspect %s: %s %s %s", op.name, efmt, op.tok, prev)
			}
		} else {
			seen[xfmt] = efmt
		}
	}
}

// split returns a slice of all subexpressions in e that are connected by op.
// For example, given 'a || (b || c) || d' with the or op,
// split returns []{d, c, b, a}.
// seen[e] is already true; any newly processed exprs are added to seen.
func (op boolOp) split(e ast.Expr, seen map[*ast.BinaryExpr]bool) (exprs []ast.Expr) {
	for {
		e = ast.Unparen(e)
		if b, ok := e.(*ast.BinaryExpr); ok && b.Op == op.tok {
			seen[b] = true
			exprs = append(exprs, op.split(b.Y, seen)...)
			e = b.X
		} else {
			exprs = append(exprs, e)
			break
		}
	}
	return
}


================================================
FILE: go/analysis/passes/bools/bools_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bools_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/bools"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, bools.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/bools/testdata/src/a/a.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the bool checker.

package a

import "io"

type T int

func (t T) Foo() int { return int(t) }

type FT func() int

var S []int

func RatherStupidConditions() {
	var f, g func() int
	if f() == 0 || f() == 0 { // OK f might have side effects
	}
	var t T
	_ = t.Foo() == 2 || t.Foo() == 2        // OK Foo might have side effects
	if v, w := f(), g(); v == w || v == w { // want `redundant or: v == w \|\| v == w`
	}
	_ = f == nil || f == nil // want `redundant or: f == nil \|\| f == nil`

	var B byte
	_ = B == byte(1) || B == byte(1) // want `redundant or: B == byte\(1\) \|\| B == byte\(1\)`
	_ = t == T(2) || t == T(2)       // want `redundant or: t == T\(2\) \|\| t == T\(2\)`
	_ = FT(f) == nil || FT(f) == nil // want `redundant or: FT\(f\) == nil \|\| FT\(f\) == nil`

	_ = (func() int)(f) == nil || (func() int)(f) == nil // want `redundant or: \(func\(\) int\)\(f\) == nil \|\| \(func\(\) int\)\(f\) == nil`
	_ = append(S, 3) == nil || append(S, 3) == nil       // OK append has side effects

	var namedFuncVar FT
	_ = namedFuncVar() == namedFuncVar() // OK still func calls

	var c chan int
	_ = 0 == <-c || 0 == <-c                                  // OK subsequent receives may yield different values
	for i, j := <-c, <-c; i == j || i == j; i, j = <-c, <-c { // want `redundant or: i == j \|\| i == j`
	}

	var i, j, k int
	_ = i+1 == 1 || i+1 == 1         // want `redundant or: i\+1 == 1 \|\| i\+1 == 1`
	_ = i == 1 || j+1 == i || i == 1 // want `redundant or: i == 1 \|\| i == 1`

	_ = i == 1 || i == 1 || f() == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || f() == 1 || i == 1 // OK f may alter i as a side effect
	_ = f() == 1 || i == 1 || i == 1 // want `redundant or: i == 1 \|\| i == 1`

	// Test partition edge cases
	_ = f() == 1 || i == 1 || i == 1 || j == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = f() == 1 || j == 1 || i == 1 || i == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || f() == 1 || i == 1 || i == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || i == 1 || f() == 1 || i == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || i == 1 || j == 1 || f() == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = j == 1 || i == 1 || i == 1 || f() == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || f() == 1 || f() == 1 || i == 1

	_ = i == 1 || (i == 1 || i == 2)             // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || (f() == 1 || i == 1)           // OK f may alter i as a side effect
	_ = i == 1 || (i == 1 || f() == 1)           // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || (i == 2 || (i == 1 || i == 3)) // want `redundant or: i == 1 \|\| i == 1`

	var a, b bool
	_ = i == 1 || (a || (i == 1 || b)) // want `redundant or: i == 1 \|\| i == 1`

	// Check that all redundant ors are flagged
	_ = j == 0 ||
		i == 1 ||
		f() == 1 ||
		j == 0 || // want `redundant or: j == 0 \|\| j == 0`
		i == 1 || // want `redundant or: i == 1 \|\| i == 1`
		i == 1 || // want `redundant or: i == 1 \|\| i == 1`
		i == 1 ||
		j == 0 ||
		k == 0

	_ = i == 1*2*3 || i == 1*2*3 // want `redundant or: i == 1\*2\*3 \|\| i == 1\*2\*3`

	// These test that redundant, suspect expressions do not trigger multiple errors.
	_ = i != 0 || i != 0 // want `redundant or: i != 0 \|\| i != 0`
	_ = i == 0 && i == 0 // want `redundant and: i == 0 && i == 0`

	// and is dual to or; check the basics and
	// let the or tests pull the rest of the weight.
	_ = 0 != <-c && 0 != <-c         // OK subsequent receives may yield different values
	_ = f() != 0 && f() != 0         // OK f might have side effects
	_ = f != nil && f != nil         // want `redundant and: f != nil && f != nil`
	_ = i != 1 && i != 1 && f() != 1 // want `redundant and: i != 1 && i != 1`
	_ = i != 1 && f() != 1 && i != 1 // OK f may alter i as a side effect
	_ = f() != 1 && i != 1 && i != 1 // want `redundant and: i != 1 && i != 1`
}

func RoyallySuspectConditions() {
	var i, j int

	_ = i == 0 || i == 1 // OK
	_ = i != 0 || i != 1 // want `suspect or: i != 0 \|\| i != 1`
	_ = i != 0 || 1 != i // want `suspect or: i != 0 \|\| 1 != i`
	_ = 0 != i || 1 != i // want `suspect or: 0 != i \|\| 1 != i`
	_ = 0 != i || i != 1 // want `suspect or: 0 != i \|\| i != 1`

	_ = (0 != i) || i != 1 // want `suspect or: 0 != i \|\| i != 1`

	_ = i+3 != 7 || j+5 == 0 || i+3 != 9 // want `suspect or: i\+3 != 7 \|\| i\+3 != 9`

	_ = i != 0 || j == 0 || i != 1 // want `suspect or: i != 0 \|\| i != 1`

	_ = i != 0 || i != 1<<4 // want `suspect or: i != 0 \|\| i != 1<<4`

	_ = i != 0 || j != 0
	_ = 0 != i || 0 != j

	var s string
	_ = s != "one" || s != "the other" // want `suspect or: s != .one. \|\| s != .the other.`

	_ = "et" != "alii" || "et" != "cetera"         // want `suspect or: .et. != .alii. \|\| .et. != .cetera.`
	_ = "me gustas" != "tu" || "le gustas" != "tu" // OK we could catch this case, but it's not worth the code

	var err error
	_ = err != nil || err != io.EOF // TODO catch this case?

	// Sanity check and.
	_ = i != 0 && i != 1 // OK
	_ = i == 0 && i == 1 // want `suspect and: i == 0 && i == 1`
	_ = i == 0 && 1 == i // want `suspect and: i == 0 && 1 == i`
	_ = 0 == i && 1 == i // want `suspect and: 0 == i && 1 == i`
	_ = 0 == i && i == 1 // want `suspect and: 0 == i && i == 1`
}


================================================
FILE: go/analysis/passes/bools/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the bool checker.

package typeparams

type T[P interface{ ~int }] struct {
	a P
}

func (t T[P]) Foo() int { return int(t.a) }

type FT[P any] func() P

func Sink[Elem any]() chan Elem {
	return make(chan Elem)
}

func RedundantConditions[P interface{ int }]() {
	type _f[P1 any] func() P1

	var f, g _f[P]
	if f() == 0 || f() == 0 { // OK f might have side effects
	}
	var t T[P]
	_ = t.Foo() == 2 || t.Foo() == 2        // OK Foo might have side effects
	if v, w := f(), g(); v == w || v == w { // want `redundant or: v == w \|\| v == w`
	}

	// error messages present type params correctly.
	_ = t == T[P]{2} || t == T[P]{2}                 // want `redundant or: t == T\[P\]\{2\} \|\| t == T\[P\]\{2\}`
	_ = FT[P](f) == nil || FT[P](f) == nil           // want `redundant or: FT\[P\]\(f\) == nil \|\| FT\[P\]\(f\) == nil`
	_ = (func() P)(f) == nil || (func() P)(f) == nil // want `redundant or: \(func\(\) P\)\(f\) == nil \|\| \(func\(\) P\)\(f\) == nil`

	var tint T[int]
	var fint _f[int]
	_ = tint == T[int]{2} || tint == T[int]{2}                 // want `redundant or: tint == T\[int\]\{2\} \|\| tint\ == T\[int\]\{2\}`
	_ = FT[int](fint) == nil || FT[int](fint) == nil           // want `redundant or: FT\[int\]\(fint\) == nil \|\| FT\[int\]\(fint\) == nil`
	_ = (func() int)(fint) == nil || (func() int)(fint) == nil // want `redundant or: \(func\(\) int\)\(fint\) == nil \|\| \(func\(\) int\)\(fint\) == nil`

	c := Sink[P]()
	_ = 0 == <-c || 0 == <-c                                  // OK subsequent receives may yield different values
	for i, j := <-c, <-c; i == j || i == j; i, j = <-c, <-c { // want `redundant or: i == j \|\| i == j`
	}

	var i, j P
	_ = i == 1 || j+1 == i || i == 1 // want `redundant or: i == 1 \|\| i == 1`
	_ = i == 1 || f() == 1 || i == 1 // OK f may alter i as a side effect
	_ = f() == 1 || i == 1 || i == 1 // want `redundant or: i == 1 \|\| i == 1`
}

func SuspectConditions[P interface{ ~int }, S interface{ ~string }]() {
	var i, j P
	_ = i == 0 || i == 1                 // OK
	_ = i+3 != 7 || j+5 == 0 || i+3 != 9 // want `suspect or: i\+3 != 7 \|\| i\+3 != 9`

	var s S
	_ = s != "one" || s != "the other" // want `suspect or: s != .one. \|\| s != .the other.`
}


================================================
FILE: go/analysis/passes/buildssa/buildssa.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package buildssa defines an Analyzer that constructs the SSA
// representation of an error-free package and returns the set of all
// functions within it. It does not report any diagnostics itself but
// may be used as an input to other analyzers.
package buildssa

import (
	"go/ast"
	"go/types"
	"iter"
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/ctrlflow"
	"golang.org/x/tools/go/ssa"
)

var Analyzer = &analysis.Analyzer{
	Name:       "buildssa",
	Doc:        "build SSA-form IR for later passes",
	URL:        "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/buildssa",
	Run:        run,
	Requires:   []*analysis.Analyzer{ctrlflow.Analyzer},
	ResultType: reflect.TypeFor[*SSA](),
	// Do not add FactTypes here: SSA construction of P must not
	// require SSA construction of all of P's dependencies.
	// (That's why we enlist the cheaper ctrlflow pass to compute
	// noreturn instead of having go/ssa + buildssa do it.)
	FactTypes: nil,
}

// SSA provides SSA-form intermediate representation for all the
// source functions in the current package.
type SSA struct {
	Pkg      *ssa.Package
	SrcFuncs []*ssa.Function
}

func run(pass *analysis.Pass) (any, error) {
	cfgs := pass.ResultOf[ctrlflow.Analyzer].(*ctrlflow.CFGs)

	// We must create a new Program for each Package because the
	// analysis API provides no place to hang a Program shared by
	// all Packages. Consequently, SSA Packages and Functions do not
	// have a canonical representation across an analysis session of
	// multiple packages. This is unlikely to be a problem in
	// practice because the analysis API essentially forces all
	// packages to be analysed independently, so any given call to
	// Analysis.Run on a package will see only SSA objects belonging
	// to a single Program.

	// Some Analyzers may need GlobalDebug, in which case we'll have
	// to set it globally, but let's wait till we need it.
	mode := ssa.BuilderMode(0)

	prog := ssa.NewProgram(pass.Fset, mode)

	// Use the result of the ctrlflow analysis to improve the SSA CFG.
	prog.SetNoReturn(cfgs.NoReturn)

	// Create SSA packages for direct imports.
	for _, p := range pass.Pkg.Imports() {
		prog.CreatePackage(p, nil, nil, true)
	}

	// Create and build the primary package.
	ssapkg := prog.CreatePackage(pass.Pkg, pass.Files, pass.TypesInfo, false)
	ssapkg.Build()

	// Compute list of source functions, including literals,
	// in source order.
	var funcs []*ssa.Function
	for _, fn := range allFunctions(pass) {
		// (init functions have distinct Func
		// objects named "init" and distinct
		// ssa.Functions named "init#1", ...)

		f := ssapkg.Prog.FuncValue(fn)
		if f == nil {
			panic(fn)
		}

		var addAnons func(f *ssa.Function)
		addAnons = func(f *ssa.Function) {
			funcs = append(funcs, f)
			for _, anon := range f.AnonFuncs {
				addAnons(anon)
			}
		}
		addAnons(f)
	}

	return &SSA{Pkg: ssapkg, SrcFuncs: funcs}, nil
}

// allFunctions returns an iterator over all named functions.
func allFunctions(pass *analysis.Pass) iter.Seq2[*ast.FuncDecl, *types.Func] {
	return func(yield func(*ast.FuncDecl, *types.Func) bool) {
		for _, file := range pass.Files {
			for _, decl := range file.Decls {
				if decl, ok := decl.(*ast.FuncDecl); ok {
					fn := pass.TypesInfo.Defs[decl.Name].(*types.Func)
					if !yield(decl, fn) {
						return
					}
				}
			}
		}
	}
}


================================================
FILE: go/analysis/passes/buildssa/buildssa_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildssa_test

import (
	"fmt"
	"os"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/buildssa"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	result := analysistest.Run(t, testdata, buildssa.Analyzer, "a")[0].Result

	ssainfo := result.(*buildssa.SSA)
	got := fmt.Sprint(ssainfo.SrcFuncs)
	want := `[a.Fib (a.T).fib a._ a._]`
	if got != want {
		t.Errorf("SSA.SrcFuncs = %s, want %s", got, want)
		for _, f := range ssainfo.SrcFuncs {
			f.WriteTo(os.Stderr)
		}
	}
}

func TestGenericDecls(t *testing.T) {
	testdata := analysistest.TestData()
	result := analysistest.Run(t, testdata, buildssa.Analyzer, "b")[0].Result

	ssainfo := result.(*buildssa.SSA)
	got := fmt.Sprint(ssainfo.SrcFuncs)
	want := `[(*b.Pointer[T]).Load b.Load b.LoadPointer]`
	if got != want {
		t.Errorf("SSA.SrcFuncs = %s, want %s", got, want)
		for _, f := range ssainfo.SrcFuncs {
			f.WriteTo(os.Stderr)
		}
	}
}

func TestImporting(t *testing.T) {
	testdata := analysistest.TestData()
	result := analysistest.Run(t, testdata, buildssa.Analyzer, "c")[0].Result

	ssainfo := result.(*buildssa.SSA)
	got := fmt.Sprint(ssainfo.SrcFuncs)
	want := `[c.A c.B]`
	if got != want {
		t.Errorf("SSA.SrcFuncs = %s, want %s", got, want)
		for _, f := range ssainfo.SrcFuncs {
			f.WriteTo(os.Stderr)
		}
	}
}


================================================
FILE: go/analysis/passes/buildssa/testdata/src/a/a.go
================================================
package a

func Fib(x int) int {
	if x < 2 {
		return x
	}
	return Fib(x-1) + Fib(x-2)
}

type T int

func (T) fib(x int) int { return Fib(x) }

func _() {
	print("hi")
}

func _() {
	print("hello")
}


================================================
FILE: go/analysis/passes/buildssa/testdata/src/b/b.go
================================================
// Package b contains declarations of generic functions.
package b

import "unsafe"

type Pointer[T any] struct {
	v unsafe.Pointer
}

func (x *Pointer[T]) Load() *T {
	return (*T)(LoadPointer(&x.v))
}

func Load[T any](x *Pointer[T]) *T {
	return x.Load()
}

func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)

var G Pointer[int]


================================================
FILE: go/analysis/passes/buildssa/testdata/src/c/c.go
================================================
// Package c is to test buildssa importing packages.
package c

import (
	"a"
	"b"
	"unsafe"
)

func A() {
	_ = a.Fib(10)
}

func B() {
	var x int
	ptr := unsafe.Pointer(&x)
	_ = b.LoadPointer(&ptr)

	m := b.G.Load()
	f := b.Load(&b.G)
	if f != m {
		panic("loads of b.G are expected to be identical")
	}
}


================================================
FILE: go/analysis/passes/buildtag/buildtag.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package buildtag defines an Analyzer that checks build tags.
package buildtag

import (
	"go/ast"
	"go/build/constraint"
	"go/parser"
	"go/token"
	"strings"
	"unicode"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

const Doc = "check //go:build and // +build directives"

var Analyzer = &analysis.Analyzer{
	Name: "buildtag",
	Doc:  Doc,
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/buildtag",
	Run:  runBuildTag,
}

func runBuildTag(pass *analysis.Pass) (any, error) {
	for _, f := range pass.Files {
		checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
		if err := checkOtherFile(pass, name); err != nil {
			return nil, err
		}
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments|parser.SkipObjectResolution)
			if err != nil {
				// Not valid Go source code - not our job to diagnose, so ignore.
				return nil, nil
			}
			checkGoFile(pass, f)
		} else {
			if err := checkOtherFile(pass, name); err != nil {
				return nil, err
			}
		}
	}
	return nil, nil
}

func checkGoFile(pass *analysis.Pass, f *ast.File) {
	var check checker
	check.init(pass)
	defer check.finish()

	for _, group := range f.Comments {
		// A +build comment is ignored after or adjoining the package declaration.
		if group.End()+1 >= f.Package {
			check.plusBuildOK = false
		}
		// A //go:build comment is ignored after the package declaration
		// (but adjoining it is OK, in contrast to +build comments).
		if group.Pos() >= f.Package {
			check.goBuildOK = false
		}

		// Check each line of a //-comment.
		for _, c := range group.List {
			// "+build" is ignored within or after a /*...*/ comment.
			if !strings.HasPrefix(c.Text, "//") {
				check.plusBuildOK = false
			}
			check.comment(c.Slash, c.Text)
		}
	}
}

func checkOtherFile(pass *analysis.Pass, filename string) error {
	var check checker
	check.init(pass)
	defer check.finish()

	// We cannot use the Go parser, since this may not be a Go source file.
	// Read the raw bytes instead.
	content, tf, err := analyzerutil.ReadFile(pass, filename)
	if err != nil {
		return err
	}

	check.file(token.Pos(tf.Base()), string(content))
	return nil
}

type checker struct {
	pass         *analysis.Pass
	plusBuildOK  bool            // "+build" lines still OK
	goBuildOK    bool            // "go:build" lines still OK
	crossCheck   bool            // cross-check go:build and +build lines when done reading file
	inStar       bool            // currently in a /* */ comment
	goBuildPos   token.Pos       // position of first go:build line found
	plusBuildPos token.Pos       // position of first "+build" line found
	goBuild      constraint.Expr // go:build constraint found
	plusBuild    constraint.Expr // AND of +build constraints found
}

func (check *checker) init(pass *analysis.Pass) {
	check.pass = pass
	check.goBuildOK = true
	check.plusBuildOK = true
	check.crossCheck = true
}

func (check *checker) file(pos token.Pos, text string) {
	// Determine cutpoint where +build comments are no longer valid.
	// They are valid in leading // comments in the file followed by
	// a blank line.
	//
	// This must be done as a separate pass because of the
	// requirement that the comment be followed by a blank line.
	var plusBuildCutoff int
	fullText := text
	for text != "" {
		i := strings.Index(text, "\n")
		if i < 0 {
			i = len(text)
		} else {
			i++
		}
		offset := len(fullText) - len(text)
		line := text[:i]
		text = text[i:]
		line = strings.TrimSpace(line)
		if !strings.HasPrefix(line, "//") && line != "" {
			break
		}
		if line == "" {
			plusBuildCutoff = offset
		}
	}

	// Process each line.
	// Must stop once we hit goBuildOK == false
	text = fullText
	check.inStar = false
	for text != "" {
		i := strings.Index(text, "\n")
		if i < 0 {
			i = len(text)
		} else {
			i++
		}
		offset := len(fullText) - len(text)
		line := text[:i]
		text = text[i:]
		check.plusBuildOK = offset < plusBuildCutoff

		if strings.HasPrefix(line, "//") {
			check.comment(pos+token.Pos(offset), line)
			continue
		}

		// Keep looking for the point at which //go:build comments
		// stop being allowed. Skip over, cut out any /* */ comments.
		for {
			line = strings.TrimSpace(line)
			if check.inStar {
				i := strings.Index(line, "*/")
				if i < 0 {
					line = ""
					break
				}
				line = line[i+len("*/"):]
				check.inStar = false
				continue
			}
			if strings.HasPrefix(line, "/*") {
				check.inStar = true
				line = line[len("/*"):]
				continue
			}
			break
		}
		if line != "" {
			// Found non-comment non-blank line.
			// Ends space for valid //go:build comments,
			// but also ends the fraction of the file we can
			// reliably parse. From this point on we might
			// incorrectly flag "comments" inside multiline
			// string constants or anything else (this might
			// not even be a Go program). So stop.
			break
		}
	}
}

func (check *checker) comment(pos token.Pos, text string) {
	if strings.HasPrefix(text, "//") {
		if strings.Contains(text, "+build") {
			check.plusBuildLine(pos, text)
		}
		if strings.Contains(text, "//go:build") {
			check.goBuildLine(pos, text)
		}
	}
	if strings.HasPrefix(text, "/*") {
		if i := strings.Index(text, "\n"); i >= 0 {
			// multiline /* */ comment - process interior lines
			check.inStar = true
			i++
			pos += token.Pos(i)
			text = text[i:]
			for text != "" {
				i := strings.Index(text, "\n")
				if i < 0 {
					i = len(text)
				} else {
					i++
				}
				line := text[:i]
				if strings.HasPrefix(line, "//") {
					check.comment(pos, line)
				}
				pos += token.Pos(i)
				text = text[i:]
			}
			check.inStar = false
		}
	}
}

func (check *checker) goBuildLine(pos token.Pos, line string) {
	if !constraint.IsGoBuild(line) {
		if !strings.HasPrefix(line, "//go:build") && constraint.IsGoBuild("//"+strings.TrimSpace(line[len("//"):])) {
			check.pass.Reportf(pos, "malformed //go:build line (space between // and go:build)")
		}
		return
	}
	if !check.goBuildOK || check.inStar {
		check.pass.Reportf(pos, "misplaced //go:build comment")
		check.crossCheck = false
		return
	}

	if check.goBuildPos == token.NoPos {
		check.goBuildPos = pos
	} else {
		check.pass.Reportf(pos, "unexpected extra //go:build line")
		check.crossCheck = false
	}

	// testing hack: stop at // ERROR
	if i := strings.Index(line, " // ERROR "); i >= 0 {
		line = line[:i]
	}

	x, err := constraint.Parse(line)
	if err != nil {
		check.pass.Reportf(pos, "%v", err)
		check.crossCheck = false
		return
	}

	check.tags(pos, x)

	if check.goBuild == nil {
		check.goBuild = x
	}
}

func (check *checker) plusBuildLine(pos token.Pos, line string) {
	line = strings.TrimSpace(line)
	if !constraint.IsPlusBuild(line) {
		// Comment with +build but not at beginning.
		// Only report early in file.
		if check.plusBuildOK && !strings.HasPrefix(line, "// want") {
			check.pass.Reportf(pos, "possible malformed +build comment")
		}
		return
	}
	if !check.plusBuildOK { // inStar implies !plusBuildOK
		check.pass.Reportf(pos, "misplaced +build comment")
		check.crossCheck = false
	}

	if check.plusBuildPos == token.NoPos {
		check.plusBuildPos = pos
	}

	// testing hack: stop at // ERROR
	if i := strings.Index(line, " // ERROR "); i >= 0 {
		line = line[:i]
	}

	fields := strings.Fields(line[len("//"):])
	// IsPlusBuildConstraint check above implies fields[0] == "+build"
	for _, arg := range fields[1:] {
		for elem := range strings.SplitSeq(arg, ",") {
			if strings.HasPrefix(elem, "!!") {
				check.pass.Reportf(pos, "invalid double negative in build constraint: %s", arg)
				check.crossCheck = false
				continue
			}
			elem = strings.TrimPrefix(elem, "!")
			for _, c := range elem {
				if !unicode.IsLetter(c) && !unicode.IsDigit(c) && c != '_' && c != '.' {
					check.pass.Reportf(pos, "invalid non-alphanumeric build constraint: %s", arg)
					check.crossCheck = false
					break
				}
			}
		}
	}

	if check.crossCheck {
		y, err := constraint.Parse(line)
		if err != nil {
			// Should never happen - constraint.Parse never rejects a // +build line.
			// Also, we just checked the syntax above.
			// Even so, report.
			check.pass.Reportf(pos, "%v", err)
			check.crossCheck = false
			return
		}
		check.tags(pos, y)

		if check.plusBuild == nil {
			check.plusBuild = y
		} else {
			check.plusBuild = &constraint.AndExpr{X: check.plusBuild, Y: y}
		}
	}
}

func (check *checker) finish() {
	if !check.crossCheck || check.plusBuildPos == token.NoPos || check.goBuildPos == token.NoPos {
		return
	}

	// Have both //go:build and // +build,
	// with no errors found (crossCheck still true).
	// Check they match.
	var want constraint.Expr
	lines, err := constraint.PlusBuildLines(check.goBuild)
	if err != nil {
		check.pass.Reportf(check.goBuildPos, "%v", err)
		return
	}
	for _, line := range lines {
		y, err := constraint.Parse(line)
		if err != nil {
			// Definitely should not happen, but not the user's fault.
			// Do not report.
			return
		}
		if want == nil {
			want = y
		} else {
			want = &constraint.AndExpr{X: want, Y: y}
		}
	}
	if want.String() != check.plusBuild.String() {
		check.pass.Reportf(check.plusBuildPos, "+build lines do not match //go:build condition")
		return
	}
}

// tags reports issues in go versions in tags within the expression e.
func (check *checker) tags(pos token.Pos, e constraint.Expr) {
	// Use Eval to visit each tag.
	_ = e.Eval(func(tag string) bool {
		if malformedGoTag(tag) {
			check.pass.Reportf(pos, "invalid go version %q in build constraint", tag)
		}
		return false // result is immaterial as Eval does not short-circuit
	})
}

// malformedGoTag returns true if a tag is likely to be a malformed
// go version constraint.
func malformedGoTag(tag string) bool {
	// Not a go version?
	if !strings.HasPrefix(tag, "go1") {
		// Check for close misspellings of the "go1." prefix.
		for _, pre := range []string{"go.", "g1.", "go"} {
			suffix := strings.TrimPrefix(tag, pre)
			if suffix != tag && validGoVersion("go1."+suffix) {
				return true
			}
		}
		return false
	}

	// The tag starts with "go1" so it is almost certainly a GoVersion.
	// Report it if it is not a valid build constraint.
	return !validGoVersion(tag)
}

// validGoVersion reports when a tag is a valid go version.
func validGoVersion(tag string) bool {
	return constraint.GoVersion(&constraint.TagExpr{Tag: tag}) != ""
}


================================================
FILE: go/analysis/passes/buildtag/buildtag_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildtag_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/buildtag"
)

func Test(t *testing.T) {
	// This test has a dedicated hack in the analysistest package:
	// Because it cares about IgnoredFiles, which most analyzers
	// ignore, the test framework will consider expectations in
	// ignore files too, but only for this analyzer.
	analysistest.Run(t, analysistest.TestData(), buildtag.Analyzer, "a", "b")
}


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the buildtag checker.

// want +1 `possible malformed \+build comment`
// +builder
// +build ignore

// Mention +build // want `possible malformed \+build comment`

// want +1 `misplaced \+build comment`
// +build nospace
//go:build ok
package a

// want +1 `misplaced \+build comment`
// +build toolate

var _ = 3

var _ = `
// +build notacomment
`


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag2.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build no

package a

// want +1 `misplaced \+build comment`
// +build toolate

// want +1 `misplaced //go:build comment`
//go:build toolate

var _ = `
// +build notacomment
`


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag3.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +3 `[+]build lines do not match //go:build condition`

//go:build good
// +build bad

package a

var _ = `
// +build notacomment
`


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag4.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !(bad || worse)
// +build !bad
// +build !worse

package a


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag5.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !(bad || worse)
// +build !bad,!worse

package a

//want +1 `misplaced \+build comment`
// +build other


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag6.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

#include "go_asm.h"

// ok because we cannot parse assembly files.
// +build no



================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag7.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build ignore

#include "go_asm.h"

// ok because we cannot parse assembly files
// the assembler would complain if we did assemble this file.
//go:build no


================================================
FILE: go/analysis/passes/buildtag/testdata/src/a/buildtag8.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +3 `\+build lines do not match //go:build condition`

//go:build something
// +build ignore

#include "go_asm.h"

// ok because we cannot parse assembly files
// the assembler would complain if we did assemble this file.
//go:build no


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +3 `invalid go version \"go1.20.1\" in build constraint`
// want +1 `invalid go version \"go1.20.1\" in build constraint`
//go:build go1.20.1
// +build go1.20.1

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers1.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is intentionally so its build tags always match.

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers2.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `invalid go version \"go120\" in build constraint`
//go:build go120

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers3.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `invalid go version \"go1..20\" in build constraint`
//go:build go1..20

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers4.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `invalid go version \"go.20\" in build constraint`
//go:build go.20

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers5.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `invalid go version \"g1.20\" in build constraint`
//go:build g1.20

package b


================================================
FILE: go/analysis/passes/buildtag/testdata/src/b/vers6.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `invalid go version \"go20\" in build constraint`
//go:build go20

package b


================================================
FILE: go/analysis/passes/cgocall/cgocall.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cgocall defines an Analyzer that detects some violations of
// the cgo pointer passing rules.
package cgocall

import (
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"log"
	"os"
	"strconv"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/typesinternal"
)

const debug = false

const Doc = `detect some violations of the cgo pointer passing rules

Check for invalid cgo pointer passing.
This looks for code that uses cgo to call C code passing values
whose types are almost always invalid according to the cgo pointer
sharing rules.
Specifically, it warns about attempts to pass a Go chan, map, func,
or slice to C, either directly, or via a pointer, array, or struct.`

var Analyzer = &analysis.Analyzer{
	Name:             "cgocall",
	Doc:              Doc,
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/cgocall",
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "runtime/cgo") {
		return nil, nil // doesn't use cgo
	}

	cgofiles, info, err := typeCheckCgoSourceFiles(pass.Fset, pass.Pkg, pass.Files, pass.TypesInfo, pass.TypesSizes)
	if err != nil {
		return nil, err
	}
	for _, f := range cgofiles {
		checkCgo(pass.Fset, f, info, pass.Reportf)
	}
	return nil, nil
}

func checkCgo(fset *token.FileSet, f *ast.File, info *types.Info, reportf func(token.Pos, string, ...any)) {
	ast.Inspect(f, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if !ok {
			return true
		}

		// Is this a C.f() call?
		var name string
		if sel, ok := ast.Unparen(call.Fun).(*ast.SelectorExpr); ok {
			if id, ok := sel.X.(*ast.Ident); ok && id.Name == "C" {
				name = sel.Sel.Name
			}
		}
		if name == "" {
			return true // not a call we need to check
		}

		// A call to C.CBytes passes a pointer but is always safe.
		if name == "CBytes" {
			return true
		}

		if debug {
			log.Printf("%s: call to C.%s", fset.Position(call.Lparen), name)
		}

		for _, arg := range call.Args {
			if !typeOKForCgoCall(cgoBaseType(info, arg), make(map[types.Type]bool)) {
				reportf(arg.Pos(), "possibly passing Go type with embedded pointer to C")
				break
			}

			// Check for passing the address of a bad type.
			if conv, ok := arg.(*ast.CallExpr); ok && len(conv.Args) == 1 &&
				isUnsafePointer(info, conv.Fun) {
				arg = conv.Args[0]
			}
			if u, ok := arg.(*ast.UnaryExpr); ok && u.Op == token.AND {
				if !typeOKForCgoCall(cgoBaseType(info, u.X), make(map[types.Type]bool)) {
					reportf(arg.Pos(), "possibly passing Go type with embedded pointer to C")
					break
				}
			}
		}
		return true
	})
}

// typeCheckCgoSourceFiles returns type-checked syntax trees for the raw
// cgo files of a package (those that import "C"). Such files are not
// Go, so there may be gaps in type information around C.f references.
//
// This checker was initially written in vet to inspect raw cgo source
// files using partial type information. However, Analyzers in the new
// analysis API are presented with the type-checked, "cooked" Go ASTs
// resulting from cgo-processing files, so we must choose between
// working with the cooked file generated by cgo (which was tried but
// proved fragile) or locating the raw cgo file (e.g. from //line
// directives) and working with that, as we now do.
//
// Specifically, we must type-check the raw cgo source files (or at
// least the subtrees needed for this analyzer) in an environment that
// simulates the rest of the already type-checked package.
//
// For example, for each raw cgo source file in the original package,
// such as this one:
//
//	package p
//	import "C"
//	import "fmt"
//	type T int
//	const k = 3
//	var x, y = fmt.Println()
//	func f() { ... }
//	func g() { ... C.malloc(k) ... }
//	func (T) f(int) string { ... }
//
// we synthesize a new ast.File, shown below, that dot-imports the
// original "cooked" package using a special name ("·this·"), so that all
// references to package members resolve correctly. (References to
// unexported names cause an "unexported" error, which we ignore.)
//
// To avoid shadowing names imported from the cooked package,
// package-level declarations in the new source file are modified so
// that they do not declare any names.
// (The cgocall analysis is concerned with uses, not declarations.)
// Specifically, type declarations are discarded;
// all names in each var and const declaration are blanked out;
// each method is turned into a regular function by turning
// the receiver into the first parameter;
// and all functions are renamed to "_".
//
//	package p
//	import . "·this·" // declares T, k, x, y, f, g, T.f
//	import "C"
//	import "fmt"
//	const _ = 3
//	var _, _ = fmt.Println()
//	func _() { ... }
//	func _() { ... C.malloc(k) ... }
//	func _(T, int) string { ... }
//
// In this way, the raw function bodies and const/var initializer
// expressions are preserved but refer to the "cooked" objects imported
// from "·this·", and none of the transformed package-level declarations
// actually declares anything. In the example above, the reference to k
// in the argument of the call to C.malloc resolves to "·this·".k, which
// has an accurate type.
//
// This approach could in principle be generalized to more complex
// analyses on raw cgo files. One could synthesize a "C" package so that
// C.f would resolve to "·this·"._C_func_f, for example. But we have
// limited ourselves here to preserving function bodies and initializer
// expressions since that is all that the cgocall analyzer needs.
func typeCheckCgoSourceFiles(fset *token.FileSet, pkg *types.Package, files []*ast.File, info *types.Info, sizes types.Sizes) ([]*ast.File, *types.Info, error) {
	const thispkg = "·this·"

	// Which files are cgo files?
	var cgoFiles []*ast.File
	importMap := map[string]*types.Package{thispkg: pkg}
	for _, raw := range files {
		// If f is a cgo-generated file, Position reports
		// the original file, honoring //line directives.
		filename := fset.Position(raw.Pos()).Filename // sic: Pos, not FileStart
		f, err := parser.ParseFile(fset, filename, nil, parser.SkipObjectResolution)
		if err != nil {
			return nil, nil, fmt.Errorf("can't parse raw cgo file: %v", err)
		}
		found := false
		for _, spec := range f.Imports {
			if spec.Path.Value == `"C"` {
				found = true
				break
			}
		}
		if !found {
			continue // not a cgo file
		}

		// Record the original import map.
		for _, spec := range raw.Imports {
			path, _ := strconv.Unquote(spec.Path.Value)
			importMap[path] = imported(info, spec)
		}

		// Add special dot-import declaration:
		//    import . "·this·"
		var decls []ast.Decl
		decls = append(decls, &ast.GenDecl{
			Tok: token.IMPORT,
			Specs: []ast.Spec{
				&ast.ImportSpec{
					Name: &ast.Ident{Name: "."},
					Path: &ast.BasicLit{
						Kind:  token.STRING,
						Value: strconv.Quote(thispkg),
					},
				},
			},
		})

		// Transform declarations from the raw cgo file.
		for _, decl := range f.Decls {
			switch decl := decl.(type) {
			case *ast.GenDecl:
				switch decl.Tok {
				case token.TYPE:
					// Discard type declarations.
					continue
				case token.IMPORT:
					// Keep imports.
				case token.VAR, token.CONST:
					// Blank the declared var/const names.
					for _, spec := range decl.Specs {
						spec := spec.(*ast.ValueSpec)
						for i := range spec.Names {
							spec.Names[i].Name = "_"
						}
					}
				}
			case *ast.FuncDecl:
				// Blank the declared func name.
				decl.Name.Name = "_"

				// Turn a method receiver:  func (T) f(P) R {...}
				// into regular parameter:  func _(T, P) R {...}
				if decl.Recv != nil {
					var params []*ast.Field
					params = append(params, decl.Recv.List...)
					params = append(params, decl.Type.Params.List...)
					decl.Type.Params.List = params
					decl.Recv = nil
				}
			}
			decls = append(decls, decl)
		}
		f.Decls = decls
		if debug {
			format.Node(os.Stderr, fset, f) // debugging
		}
		cgoFiles = append(cgoFiles, f)
	}
	if cgoFiles == nil {
		return nil, nil, nil // nothing to do (can't happen?)
	}

	// Type-check the synthetic files.
	tc := &types.Config{
		FakeImportC: true,
		Importer: importerFunc(func(path string) (*types.Package, error) {
			return importMap[path], nil
		}),
		Sizes: sizes,
		Error: func(error) {}, // ignore errors (e.g. unused import)
	}
	setGoVersion(tc, pkg)

	// It's tempting to record the new types in the
	// existing pass.TypesInfo, but we don't own it.
	altInfo := &types.Info{
		Types: make(map[ast.Expr]types.TypeAndValue),
	}
	tc.Check(pkg.Path(), fset, cgoFiles, altInfo)

	return cgoFiles, altInfo, nil
}

// cgoBaseType tries to look through type conversions involving
// unsafe.Pointer to find the real type. It converts:
//
//	unsafe.Pointer(x) => x
//	*(*unsafe.Pointer)(unsafe.Pointer(&x)) => x
func cgoBaseType(info *types.Info, arg ast.Expr) types.Type {
	switch arg := arg.(type) {
	case *ast.CallExpr:
		if len(arg.Args) == 1 && isUnsafePointer(info, arg.Fun) {
			return cgoBaseType(info, arg.Args[0])
		}
	case *ast.StarExpr:
		call, ok := arg.X.(*ast.CallExpr)
		if !ok || len(call.Args) != 1 {
			break
		}
		// Here arg is *f(v).
		t := info.Types[call.Fun].Type
		if t == nil {
			break
		}
		ptr, ok := t.Underlying().(*types.Pointer)
		if !ok {
			break
		}
		// Here arg is *(*p)(v)
		elem, ok := ptr.Elem().Underlying().(*types.Basic)
		if !ok || elem.Kind() != types.UnsafePointer {
			break
		}
		// Here arg is *(*unsafe.Pointer)(v)
		call, ok = call.Args[0].(*ast.CallExpr)
		if !ok || len(call.Args) != 1 {
			break
		}
		// Here arg is *(*unsafe.Pointer)(f(v))
		if !isUnsafePointer(info, call.Fun) {
			break
		}
		// Here arg is *(*unsafe.Pointer)(unsafe.Pointer(v))
		u, ok := call.Args[0].(*ast.UnaryExpr)
		if !ok || u.Op != token.AND {
			break
		}
		// Here arg is *(*unsafe.Pointer)(unsafe.Pointer(&v))
		return cgoBaseType(info, u.X)
	}

	return info.Types[arg].Type
}

// typeOKForCgoCall reports whether the type of arg is OK to pass to a
// C function using cgo. This is not true for Go types with embedded
// pointers. m is used to avoid infinite recursion on recursive types.
func typeOKForCgoCall(t types.Type, m map[types.Type]bool) bool {
	if t == nil || m[t] {
		return true
	}
	m[t] = true
	switch t := t.Underlying().(type) {
	case *types.Chan, *types.Map, *types.Signature, *types.Slice:
		return false
	case *types.Pointer:
		return typeOKForCgoCall(t.Elem(), m)
	case *types.Array:
		return typeOKForCgoCall(t.Elem(), m)
	case *types.Struct:
		for field := range t.Fields() {
			if !typeOKForCgoCall(field.Type(), m) {
				return false
			}
		}
	}
	return true
}

func isUnsafePointer(info *types.Info, e ast.Expr) bool {
	t := info.Types[e].Type
	return t != nil && t.Underlying() == types.Typ[types.UnsafePointer]
}

type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }

// TODO(adonovan): make this a library function or method of Info.
func imported(info *types.Info, spec *ast.ImportSpec) *types.Package {
	obj, ok := info.Implicits[spec]
	if !ok {
		obj = info.Defs[spec.Name] // renaming import
	}
	return obj.(*types.PkgName).Imported()
}


================================================
FILE: go/analysis/passes/cgocall/cgocall_go120.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.21

package cgocall

import "go/types"

func setGoVersion(tc *types.Config, pkg *types.Package) {
	// no types.Package.GoVersion until Go 1.21
}


================================================
FILE: go/analysis/passes/cgocall/cgocall_go121.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.21

package cgocall

import "go/types"

func setGoVersion(tc *types.Config, pkg *types.Package) {
	tc.GoVersion = pkg.GoVersion()
}


================================================
FILE: go/analysis/passes/cgocall/cgocall_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cgocall_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/cgocall"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, cgocall.Analyzer, "a", "b", "c", "typeparams")
}


================================================
FILE: go/analysis/passes/cgocall/testdata/src/a/cgo.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the cgo checker.

package a

// void f(void *ptr) {}
import "C"

import "unsafe"

func CgoTests() {
	var c chan bool
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&c))) // want "embedded pointer"
	C.f(unsafe.Pointer(&c))                     // want "embedded pointer"

	var m map[string]string
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&m))) // want "embedded pointer"
	C.f(unsafe.Pointer(&m))                     // want "embedded pointer"

	var f func()
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&f))) // want "embedded pointer"
	C.f(unsafe.Pointer(&f))                     // want "embedded pointer"

	var s []int
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&s))) // want "embedded pointer"
	C.f(unsafe.Pointer(&s))                     // want "embedded pointer"

	var a [1][]int
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&a))) // want "embedded pointer"
	C.f(unsafe.Pointer(&a))                     // want "embedded pointer"

	var st struct{ f []int }
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&st))) // want "embedded pointer"
	C.f(unsafe.Pointer(&st))                     // want "embedded pointer"

	var st3 S
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&st3))) // want "embedded pointer"
	C.f(unsafe.Pointer(&st3))                     // want "embedded pointer"

	// The following cases are OK.
	var i int
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&i)))
	C.f(unsafe.Pointer(&i))

	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&s[0])))
	C.f(unsafe.Pointer(&s[0]))

	var a2 [1]int
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&a2)))
	C.f(unsafe.Pointer(&a2))

	var st2 struct{ i int }
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&st2)))
	C.f(unsafe.Pointer(&st2))

	var st4 S2
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&st4)))
	C.f(unsafe.Pointer(&st4))

	type cgoStruct struct{ p *cgoStruct }
	C.f(unsafe.Pointer(&cgoStruct{}))

	C.CBytes([]byte("hello"))
}

type S struct{ slice []int }

type S2 struct{ int int }


================================================
FILE: go/analysis/passes/cgocall/testdata/src/a/cgo3.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

// The purpose of this inherited test is unclear.

import "C"

const x = 1

var a, b = 1, 2

func F() {
}

func FAD(int, string) bool {
	C.malloc(3)
	return true
}


================================================
FILE: go/analysis/passes/cgocall/testdata/src/b/b.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test the cgo checker on a file that doesn't use cgo, but has an
// import named "C".

package b

import C "fmt"

import "unsafe"

func init() {
	var f func()
	C.Println(unsafe.Pointer(&f))

	// Passing a pointer (via a slice), but C is fmt, not cgo.
	C.Println([]int{3})
}


================================================
FILE: go/analysis/passes/cgocall/testdata/src/c/c.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test the cgo checker on a file that doesn't use cgo.

package c

import "unsafe"

// Passing a pointer (via the slice), but C isn't cgo.
var _ = C.f(unsafe.Pointer(new([]int)))

var C struct{ f func(interface{}) int }


================================================
FILE: go/analysis/passes/cgocall/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the cgo checker.

package a

// void f(void *ptr) {}
import "C"

import "unsafe"

func CgoTest[T any]() {
	var c chan bool
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&c))) // want "embedded pointer"
	C.f(unsafe.Pointer(&c))                     // want "embedded pointer"

	var schan S[chan bool]
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&schan))) // want "embedded pointer"
	C.f(unsafe.Pointer(&schan))                     // want "embedded pointer"

	var x T
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&x))) // no findings as T is not known compile-time
	C.f(unsafe.Pointer(&x))

	// instantiating CgoTest should not yield any warnings
	CgoTest[chan bool]()

	var sint S[int]
	C.f(*(*unsafe.Pointer)(unsafe.Pointer(&sint)))
	C.f(unsafe.Pointer(&sint))
}

type S[X any] struct {
	val X
}


================================================
FILE: go/analysis/passes/composite/composite.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package composite defines an Analyzer that checks for unkeyed
// composite literals.
package composite

import (
	"fmt"
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typeparams"
)

const Doc = `check for unkeyed composite literals

This analyzer reports a diagnostic for composite literals of struct
types imported from another package that do not use the field-keyed
syntax. Such literals are fragile because the addition of a new field
(even if unexported) to the struct will cause compilation to fail.

As an example,

	err = &net.DNSConfigError{err}

should be replaced by:

	err = &net.DNSConfigError{Err: err}
`

var Analyzer = &analysis.Analyzer{
	Name:             "composites",
	Doc:              Doc,
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/composite",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run:              run,
}

var whitelist = true

func init() {
	Analyzer.Flags.BoolVar(&whitelist, "whitelist", whitelist, "use composite white list; for testing only")
}

// runUnkeyedLiteral checks if a composite literal is a struct literal with
// unkeyed fields.
func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CompositeLit)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		cl := n.(*ast.CompositeLit)

		typ := pass.TypesInfo.Types[cl].Type
		if typ == nil {
			// cannot determine composite literals' type, skip it
			return
		}
		typeName := typ.String()
		if whitelist && unkeyedLiteral[typeName] {
			// skip whitelisted types
			return
		}
		var structuralTypes []types.Type
		switch typ := types.Unalias(typ).(type) {
		case *types.TypeParam:
			terms, err := typeparams.StructuralTerms(typ)
			if err != nil {
				return // invalid type
			}
			for _, term := range terms {
				structuralTypes = append(structuralTypes, term.Type())
			}
		default:
			structuralTypes = append(structuralTypes, typ)
		}

		for _, typ := range structuralTypes {
			strct, ok := typeparams.Deref(typ).Underlying().(*types.Struct)
			if !ok {
				// skip non-struct composite literals
				continue
			}
			if isLocalType(pass, typ) {
				// allow unkeyed locally defined composite literal
				continue
			}

			// check if the struct contains an unkeyed field
			allKeyValue := true
			var suggestedFixAvailable = len(cl.Elts) == strct.NumFields()
			var missingKeys []analysis.TextEdit
			for i, e := range cl.Elts {
				if _, ok := e.(*ast.KeyValueExpr); !ok {
					allKeyValue = false
					if i >= strct.NumFields() {
						break
					}
					field := strct.Field(i)
					if !field.Exported() {
						// Adding unexported field names for structs not defined
						// locally will not work.
						suggestedFixAvailable = false
						break
					}
					missingKeys = append(missingKeys, analysis.TextEdit{
						Pos:     e.Pos(),
						End:     e.Pos(),
						NewText: fmt.Appendf(nil, "%s: ", field.Name()),
					})
				}
			}
			if allKeyValue {
				// all the struct fields are keyed
				continue
			}

			diag := analysis.Diagnostic{
				Pos:     cl.Pos(),
				End:     cl.End(),
				Message: fmt.Sprintf("%s struct literal uses unkeyed fields", typeName),
			}
			if suggestedFixAvailable {
				diag.SuggestedFixes = []analysis.SuggestedFix{{
					Message:   "Add field names to struct literal",
					TextEdits: missingKeys,
				}}
			}
			pass.Report(diag)
			return
		}
	})
	return nil, nil
}

// isLocalType reports whether typ belongs to the same package as pass.
// TODO(adonovan): local means "internal to a function"; rename to isSamePackageType.
func isLocalType(pass *analysis.Pass, typ types.Type) bool {
	switch x := types.Unalias(typ).(type) {
	case *types.Struct:
		// struct literals are local types
		return true
	case *types.Pointer:
		return isLocalType(pass, x.Elem())
	case interface{ Obj() *types.TypeName }: // *Named or *TypeParam (aliases were removed already)
		// names in package foo are local to foo_test too
		return x.Obj().Pkg() != nil &&
			strings.TrimSuffix(x.Obj().Pkg().Path(), "_test") == strings.TrimSuffix(pass.Pkg.Path(), "_test")
	}
	return false
}


================================================
FILE: go/analysis/passes/composite/composite_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package composite_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/composite"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, composite.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/composite/testdata/src/a/a.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the test for untagged struct literals.

package a

import (
	"flag"
	"go/scanner"
	"go/token"
	"image"
	"sync"
	"unicode"
)

var Okay1 = []string{
	"Name",
	"Usage",
	"DefValue",
}

var Okay2 = map[string]bool{
	"Name":     true,
	"Usage":    true,
	"DefValue": true,
}

var Okay3 = struct {
	X string
	Y string
	Z string
}{
	"Name",
	"Usage",
	"DefValue",
}

var Okay4 = []struct {
	A int
	B int
}{
	{1, 2},
	{3, 4},
}

type MyStruct struct {
	X string
	Y string
	Z string
}

var Okay5 = &MyStruct{
	"Name",
	"Usage",
	"DefValue",
}

var Okay6 = []MyStruct{
	{"foo", "bar", "baz"},
	{"aa", "bb", "cc"},
}

var Okay7 = []*MyStruct{
	{"foo", "bar", "baz"},
	{"aa", "bb", "cc"},
}

// Testing is awkward because we need to reference things from a separate package
// to trigger the warnings.

var goodStructLiteral = flag.Flag{
	Name:  "Name",
	Usage: "Usage",
}
var badStructLiteral = flag.Flag{ // want "unkeyed fields"
	"Name",
	"Usage",
	nil, // Value
	"DefValue",
}
var tooManyFieldsStructLiteral = flag.Flag{ // want "unkeyed fields"
	"Name",
	"Usage",
	nil, // Value
	"DefValue",
	"Extra Field",
}
var tooFewFieldsStructLiteral = flag.Flag{ // want "unkeyed fields"
	"Name",
	"Usage",
	nil, // Value
}

var delta [3]rune

// SpecialCase is a named slice of CaseRange to test issue 9171.
var goodNamedSliceLiteral = unicode.SpecialCase{
	{Lo: 1, Hi: 2, Delta: delta},
	unicode.CaseRange{Lo: 1, Hi: 2, Delta: delta},
}
var badNamedSliceLiteral = unicode.SpecialCase{
	{1, 2, delta},                  // want "unkeyed fields"
	unicode.CaseRange{1, 2, delta}, // want "unkeyed fields"
}

// ErrorList is a named slice, so no warnings should be emitted.
var goodScannerErrorList = scanner.ErrorList{
	&scanner.Error{Msg: "foobar"},
}
var badScannerErrorList = scanner.ErrorList{
	&scanner.Error{token.Position{}, "foobar"}, // want "unkeyed fields"
}

// sync.Mutex has unexported fields. We expect a diagnostic but no
// suggested fix.
var mu = sync.Mutex{0, 0} // want "unkeyed fields"

// Check whitelisted structs: if vet is run with --compositewhitelist=false,
// this line triggers an error.
var whitelistedPoint = image.Point{1, 2}

// Do not check type from unknown package.
// See issue 15408.
var unknownPkgVar = unicode.NoSuchType{"foo", "bar"}

// A named pointer slice of CaseRange to test issue 23539. In
// particular, we're interested in how some slice elements omit their
// type.
var goodNamedPointerSliceLiteral = []*unicode.CaseRange{
	{Lo: 1, Hi: 2},
	&unicode.CaseRange{Lo: 1, Hi: 2},
}
var badNamedPointerSliceLiteral = []*unicode.CaseRange{
	{1, 2, delta},                   // want "unkeyed fields"
	&unicode.CaseRange{1, 2, delta}, // want "unkeyed fields"
}

// unicode.Range16 is whitelisted, so there'll be no vet error
var range16 = unicode.Range16{0xfdd0, 0xfdef, 1}

// unicode.Range32 is whitelisted, so there'll be no vet error
var range32 = unicode.Range32{0x1fffe, 0x1ffff, 1}


================================================
FILE: go/analysis/passes/composite/testdata/src/a/a.go.golden
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the test for untagged struct literals.

package a

import (
	"flag"
	"go/scanner"
	"go/token"
	"image"
	"sync"
	"unicode"
)

var Okay1 = []string{
	"Name",
	"Usage",
	"DefValue",
}

var Okay2 = map[string]bool{
	"Name":     true,
	"Usage":    true,
	"DefValue": true,
}

var Okay3 = struct {
	X string
	Y string
	Z string
}{
	"Name",
	"Usage",
	"DefValue",
}

var Okay4 = []struct {
	A int
	B int
}{
	{1, 2},
	{3, 4},
}

type MyStruct struct {
	X string
	Y string
	Z string
}

var Okay5 = &MyStruct{
	"Name",
	"Usage",
	"DefValue",
}

var Okay6 = []MyStruct{
	{"foo", "bar", "baz"},
	{"aa", "bb", "cc"},
}

var Okay7 = []*MyStruct{
	{"foo", "bar", "baz"},
	{"aa", "bb", "cc"},
}

// Testing is awkward because we need to reference things from a separate package
// to trigger the warnings.

var goodStructLiteral = flag.Flag{
	Name:  "Name",
	Usage: "Usage",
}
var badStructLiteral = flag.Flag{ // want "unkeyed fields"
	Name:     "Name",
	Usage:    "Usage",
	Value:    nil, // Value
	DefValue: "DefValue",
}
var tooManyFieldsStructLiteral = flag.Flag{ // want "unkeyed fields"
	"Name",
	"Usage",
	nil, // Value
	"DefValue",
	"Extra Field",
}
var tooFewFieldsStructLiteral = flag.Flag{ // want "unkeyed fields"
	"Name",
	"Usage",
	nil, // Value
}

var delta [3]rune

// SpecialCase is a named slice of CaseRange to test issue 9171.
var goodNamedSliceLiteral = unicode.SpecialCase{
	{Lo: 1, Hi: 2, Delta: delta},
	unicode.CaseRange{Lo: 1, Hi: 2, Delta: delta},
}
var badNamedSliceLiteral = unicode.SpecialCase{
	{Lo: 1, Hi: 2, Delta: delta},                  // want "unkeyed fields"
	unicode.CaseRange{Lo: 1, Hi: 2, Delta: delta}, // want "unkeyed fields"
}

// ErrorList is a named slice, so no warnings should be emitted.
var goodScannerErrorList = scanner.ErrorList{
	&scanner.Error{Msg: "foobar"},
}
var badScannerErrorList = scanner.ErrorList{
	&scanner.Error{Pos: token.Position{}, Msg: "foobar"}, // want "unkeyed fields"
}

// sync.Mutex has unexported fields. We expect a diagnostic but no
// suggested fix.
var mu = sync.Mutex{0, 0} // want "unkeyed fields"

// Check whitelisted structs: if vet is run with --compositewhitelist=false,
// this line triggers an error.
var whitelistedPoint = image.Point{1, 2}

// Do not check type from unknown package.
// See issue 15408.
var unknownPkgVar = unicode.NoSuchType{"foo", "bar"}

// A named pointer slice of CaseRange to test issue 23539. In
// particular, we're interested in how some slice elements omit their
// type.
var goodNamedPointerSliceLiteral = []*unicode.CaseRange{
	{Lo: 1, Hi: 2},
	&unicode.CaseRange{Lo: 1, Hi: 2},
}
var badNamedPointerSliceLiteral = []*unicode.CaseRange{
	{Lo: 1, Hi: 2, Delta: delta},                   // want "unkeyed fields"
	&unicode.CaseRange{Lo: 1, Hi: 2, Delta: delta}, // want "unkeyed fields"
}

// unicode.Range16 is whitelisted, so there'll be no vet error
var range16 = unicode.Range16{0xfdd0, 0xfdef, 1}

// unicode.Range32 is whitelisted, so there'll be no vet error
var range32 = unicode.Range32{0x1fffe, 0x1ffff, 1}


================================================
FILE: go/analysis/passes/composite/testdata/src/a/a_fuzz_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import "testing"

var fuzzTargets = []testing.InternalFuzzTarget{
	{"Fuzz", Fuzz},
}

func Fuzz(f *testing.F) {}


================================================
FILE: go/analysis/passes/composite/testdata/src/a/a_fuzz_test.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import "testing"

var fuzzTargets = []testing.InternalFuzzTarget{
	{"Fuzz", Fuzz},
}

func Fuzz(f *testing.F) {}


================================================
FILE: go/analysis/passes/composite/testdata/src/typeparams/lib/lib.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lib

type Struct struct{ F int }
type Slice []int
type Map map[int]int


================================================
FILE: go/analysis/passes/composite/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "typeparams/lib"

type localStruct struct{ F int }

func F[
	T1 ~struct{ f int },
	T2a localStruct,
	T2b lib.Struct,
	T3 ~[]int,
	T4 lib.Slice,
	T5 ~map[int]int,
	T6 lib.Map,
]() {
	_ = T1{2}
	_ = T2a{2}
	_ = T2b{2} // want "unkeyed fields"
	_ = T3{1, 2}
	_ = T4{1, 2}
	_ = T5{1: 2}
	_ = T6{1: 2}
}


================================================
FILE: go/analysis/passes/composite/testdata/src/typeparams/typeparams.go.golden
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "typeparams/lib"

type localStruct struct{ F int }

func F[
	T1 ~struct{ f int },
	T2a localStruct,
	T2b lib.Struct,
	T3 ~[]int,
	T4 lib.Slice,
	T5 ~map[int]int,
	T6 lib.Map,
]() {
	_ = T1{2}
	_ = T2a{2}
	_ = T2b{F: 2} // want "unkeyed fields"
	_ = T3{1, 2}
	_ = T4{1, 2}
	_ = T5{1: 2}
	_ = T6{1: 2}
}


================================================
FILE: go/analysis/passes/composite/whitelist.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package composite

// unkeyedLiteral is a white list of types in the standard packages
// that are used with unkeyed literals we deem to be acceptable.
var unkeyedLiteral = map[string]bool{
	// These image and image/color struct types are frozen. We will never add fields to them.
	"image/color.Alpha16": true,
	"image/color.Alpha":   true,
	"image/color.CMYK":    true,
	"image/color.Gray16":  true,
	"image/color.Gray":    true,
	"image/color.NRGBA64": true,
	"image/color.NRGBA":   true,
	"image/color.NYCbCrA": true,
	"image/color.RGBA64":  true,
	"image/color.RGBA":    true,
	"image/color.YCbCr":   true,
	"image.Point":         true,
	"image.Rectangle":     true,
	"image.Uniform":       true,

	"unicode.Range16": true,
	"unicode.Range32": true,

	// These four structs are used in generated test main files,
	// but the generator can be trusted.
	"testing.InternalBenchmark":  true,
	"testing.InternalExample":    true,
	"testing.InternalTest":       true,
	"testing.InternalFuzzTarget": true,
}


================================================
FILE: go/analysis/passes/copylock/copylock.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package copylock defines an Analyzer that checks for locks
// erroneously passed by value.
package copylock

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

const Doc = `check for locks erroneously passed by value

Inadvertently copying a value containing a lock, such as sync.Mutex or
sync.WaitGroup, may cause both copies to malfunction. Generally such
values should be referred to through a pointer.`

var Analyzer = &analysis.Analyzer{
	Name:             "copylocks",
	Doc:              Doc,
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/copylock",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	var goversion string // effective file version ("" => unknown)
	nodeFilter := []ast.Node{
		(*ast.AssignStmt)(nil),
		(*ast.CallExpr)(nil),
		(*ast.CompositeLit)(nil),
		(*ast.File)(nil),
		(*ast.FuncDecl)(nil),
		(*ast.FuncLit)(nil),
		(*ast.GenDecl)(nil),
		(*ast.RangeStmt)(nil),
		(*ast.ReturnStmt)(nil),
	}
	inspect.WithStack(nodeFilter, func(node ast.Node, push bool, stack []ast.Node) bool {
		if !push {
			return false
		}
		switch node := node.(type) {
		case *ast.File:
			goversion = versions.FileVersion(pass.TypesInfo, node)
		case *ast.RangeStmt:
			checkCopyLocksRange(pass, node)
		case *ast.FuncDecl:
			checkCopyLocksFunc(pass, node.Name.Name, node.Recv, node.Type)
		case *ast.FuncLit:
			checkCopyLocksFunc(pass, "func", nil, node.Type)
		case *ast.CallExpr:
			checkCopyLocksCallExpr(pass, node)
		case *ast.AssignStmt:
			checkCopyLocksAssign(pass, node, goversion, parent(stack))
		case *ast.GenDecl:
			checkCopyLocksGenDecl(pass, node)
		case *ast.CompositeLit:
			checkCopyLocksCompositeLit(pass, node)
		case *ast.ReturnStmt:
			checkCopyLocksReturnStmt(pass, node)
		}
		return true
	})
	return nil, nil
}

// checkCopyLocksAssign checks whether an assignment
// copies a lock.
func checkCopyLocksAssign(pass *analysis.Pass, assign *ast.AssignStmt, goversion string, parent ast.Node) {
	lhs := assign.Lhs
	for i, x := range assign.Rhs {
		if path := lockPathRhs(pass, x); path != nil {
			pass.ReportRangef(x, "assignment copies lock value to %v: %v", astutil.Format(pass.Fset, assign.Lhs[i]), path)
			lhs = nil // An lhs has been reported. We prefer the assignment warning and do not report twice.
		}
	}

	// After GoVersion 1.22, loop variables are implicitly copied on each iteration.
	// So a for statement may inadvertently copy a lock when any of the
	// iteration variables contain locks.
	if assign.Tok == token.DEFINE && versions.AtLeast(goversion, versions.Go1_22) {
		if parent, _ := parent.(*ast.ForStmt); parent != nil && parent.Init == assign {
			for _, l := range lhs {
				if id, ok := l.(*ast.Ident); ok && id.Name != "_" {
					if obj := pass.TypesInfo.Defs[id]; obj != nil && obj.Type() != nil {
						if path := lockPath(pass.Pkg, obj.Type(), nil); path != nil {
							pass.ReportRangef(l, "for loop iteration copies lock value to %v: %v", astutil.Format(pass.Fset, l), path)
						}
					}
				}
			}
		}
	}
}

// checkCopyLocksGenDecl checks whether lock is copied
// in variable declaration.
func checkCopyLocksGenDecl(pass *analysis.Pass, gd *ast.GenDecl) {
	if gd.Tok != token.VAR {
		return
	}
	for _, spec := range gd.Specs {
		valueSpec := spec.(*ast.ValueSpec)
		for i, x := range valueSpec.Values {
			if path := lockPathRhs(pass, x); path != nil {
				pass.ReportRangef(x, "variable declaration copies lock value to %v: %v", valueSpec.Names[i].Name, path)
			}
		}
	}
}

// checkCopyLocksCompositeLit detects lock copy inside a composite literal
func checkCopyLocksCompositeLit(pass *analysis.Pass, cl *ast.CompositeLit) {
	for _, x := range cl.Elts {
		if node, ok := x.(*ast.KeyValueExpr); ok {
			x = node.Value
		}
		if path := lockPathRhs(pass, x); path != nil {
			pass.ReportRangef(x, "literal copies lock value from %v: %v", astutil.Format(pass.Fset, x), path)
		}
	}
}

// checkCopyLocksReturnStmt detects lock copy in return statement
func checkCopyLocksReturnStmt(pass *analysis.Pass, rs *ast.ReturnStmt) {
	for _, x := range rs.Results {
		if path := lockPathRhs(pass, x); path != nil {
			pass.ReportRangef(x, "return copies lock value: %v", path)
		}
	}
}

// checkCopyLocksCallExpr detects lock copy in the arguments to a function call
func checkCopyLocksCallExpr(pass *analysis.Pass, ce *ast.CallExpr) {
	var id *ast.Ident
	switch fun := ce.Fun.(type) {
	case *ast.Ident:
		id = fun
	case *ast.SelectorExpr:
		id = fun.Sel
	}
	if fun, ok := pass.TypesInfo.Uses[id].(*types.Builtin); ok {
		switch fun.Name() {
		case "len", "cap", "Sizeof", "Offsetof", "Alignof":
			// The argument of this operation is used only
			// for its type (e.g. len(array)), or the operation
			// does not copy a lock (e.g. len(slice)).
			return
		}
	}
	for _, x := range ce.Args {
		if path := lockPathRhs(pass, x); path != nil {
			pass.ReportRangef(x, "call of %s copies lock value: %v", astutil.Format(pass.Fset, ce.Fun), path)
		}
	}
}

// checkCopyLocksFunc checks whether a function might
// inadvertently copy a lock, by checking whether
// its receiver, parameters, or return values
// are locks.
func checkCopyLocksFunc(pass *analysis.Pass, name string, recv *ast.FieldList, typ *ast.FuncType) {
	if recv != nil && len(recv.List) > 0 {
		expr := recv.List[0].Type
		if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type, nil); path != nil {
			pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
		}
	}

	if typ.Params != nil {
		for _, field := range typ.Params.List {
			expr := field.Type
			if path := lockPath(pass.Pkg, pass.TypesInfo.Types[expr].Type, nil); path != nil {
				pass.ReportRangef(expr, "%s passes lock by value: %v", name, path)
			}
		}
	}

	// Don't check typ.Results. If T has a Lock field it's OK to write
	//     return T{}
	// because that is returning the zero value. Leave result checking
	// to the return statement.
}

// checkCopyLocksRange checks whether a range statement
// might inadvertently copy a lock by checking whether
// any of the range variables are locks.
func checkCopyLocksRange(pass *analysis.Pass, r *ast.RangeStmt) {
	checkCopyLocksRangeVar(pass, r.Tok, r.Key)
	checkCopyLocksRangeVar(pass, r.Tok, r.Value)
}

func checkCopyLocksRangeVar(pass *analysis.Pass, rtok token.Token, e ast.Expr) {
	if e == nil {
		return
	}
	id, isId := e.(*ast.Ident)
	if isId && id.Name == "_" {
		return
	}

	var typ types.Type
	if rtok == token.DEFINE {
		if !isId {
			return
		}
		obj := pass.TypesInfo.Defs[id]
		if obj == nil {
			return
		}
		typ = obj.Type()
	} else {
		typ = pass.TypesInfo.Types[e].Type
	}

	if typ == nil {
		return
	}
	if path := lockPath(pass.Pkg, typ, nil); path != nil {
		pass.Reportf(e.Pos(), "range var %s copies lock: %v", astutil.Format(pass.Fset, e), path)
	}
}

type typePath []string

// String pretty-prints a typePath.
func (path typePath) String() string {
	n := len(path)
	var buf bytes.Buffer
	for i := range path {
		if i > 0 {
			fmt.Fprint(&buf, " contains ")
		}
		// The human-readable path is in reverse order, outermost to innermost.
		fmt.Fprint(&buf, path[n-i-1])
	}
	return buf.String()
}

func lockPathRhs(pass *analysis.Pass, x ast.Expr) typePath {
	x = ast.Unparen(x) // ignore parens on rhs

	if _, ok := x.(*ast.CompositeLit); ok {
		return nil
	}
	if _, ok := x.(*ast.CallExpr); ok {
		// A call may return a zero value.
		return nil
	}
	if star, ok := x.(*ast.StarExpr); ok {
		if _, ok := ast.Unparen(star.X).(*ast.CallExpr); ok {
			// A call may return a pointer to a zero value.
			return nil
		}
	}
	if tv, ok := pass.TypesInfo.Types[x]; ok && tv.IsValue() {
		return lockPath(pass.Pkg, tv.Type, nil)
	}
	return nil
}

// lockPath returns a typePath describing the location of a lock value
// contained in typ. If there is no contained lock, it returns nil.
//
// The seen map is used to short-circuit infinite recursion due to type cycles.
func lockPath(tpkg *types.Package, typ types.Type, seen map[types.Type]bool) typePath {
	if typ == nil || seen[typ] {
		return nil
	}
	if seen == nil {
		seen = make(map[types.Type]bool)
	}
	seen[typ] = true

	if tpar, ok := types.Unalias(typ).(*types.TypeParam); ok {
		terms, err := typeparams.StructuralTerms(tpar)
		if err != nil {
			return nil // invalid type
		}
		for _, term := range terms {
			subpath := lockPath(tpkg, term.Type(), seen)
			if len(subpath) > 0 {
				if term.Tilde() {
					// Prepend a tilde to our lock path entry to clarify the resulting
					// diagnostic message. Consider the following example:
					//
					//  func _[Mutex interface{ ~sync.Mutex; M() }](m Mutex) {}
					//
					// Here the naive error message will be something like "passes lock
					// by value: Mutex contains sync.Mutex". This is misleading because
					// the local type parameter doesn't actually contain sync.Mutex,
					// which lacks the M method.
					//
					// With tilde, it is clearer that the containment is via an
					// approximation element.
					subpath[len(subpath)-1] = "~" + subpath[len(subpath)-1]
				}
				return append(subpath, typ.String())
			}
		}
		return nil
	}

	for {
		atyp, ok := typ.Underlying().(*types.Array)
		if !ok {
			break
		}
		typ = atyp.Elem()
	}

	ttyp, ok := typ.Underlying().(*types.Tuple)
	if ok {
		for v := range ttyp.Variables() {
			subpath := lockPath(tpkg, v.Type(), seen)
			if subpath != nil {
				return append(subpath, typ.String())
			}
		}
		return nil
	}

	// We're only interested in the case in which the underlying
	// type is a struct. (Interfaces and pointers are safe to copy.)
	styp, ok := typ.Underlying().(*types.Struct)
	if !ok {
		return nil
	}

	// We're looking for cases in which a pointer to this type
	// is a sync.Locker, but a value is not. This differentiates
	// embedded interfaces from embedded values.
	if types.Implements(types.NewPointer(typ), lockerType) && !types.Implements(typ, lockerType) {
		return []string{typ.String()}
	}

	// In go1.10, sync.noCopy did not implement Locker.
	// (The Unlock method was added only in CL 121876.)
	// TODO(adonovan): remove workaround when we drop go1.10.
	if typesinternal.IsTypeNamed(typ, "sync", "noCopy") {
		return []string{typ.String()}
	}

	nfields := styp.NumFields()
	for i := range nfields {
		ftyp := styp.Field(i).Type()
		subpath := lockPath(tpkg, ftyp, seen)
		if subpath != nil {
			return append(subpath, typ.String())
		}
	}

	return nil
}

// parent returns the second from the last node on stack if it exists.
func parent(stack []ast.Node) ast.Node {
	if len(stack) >= 2 {
		return stack[len(stack)-2]
	}
	return nil
}

var lockerType *types.Interface

// Construct a sync.Locker interface type.
func init() {
	nullary := types.NewSignatureType(nil, nil, nil, nil, nil, false) // func()
	methods := []*types.Func{
		types.NewFunc(token.NoPos, nil, "Lock", nullary),
		types.NewFunc(token.NoPos, nil, "Unlock", nullary),
	}
	lockerType = types.NewInterface(methods, nil).Complete()
}


================================================
FILE: go/analysis/passes/copylock/copylock_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package copylock_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/copylock"
	"golang.org/x/tools/internal/testfiles"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, copylock.Analyzer, "a", "typeparams", "issue67787", "unfortunate")
}

func TestVersions22(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "src", "forstmt", "go22.txtar"))
	analysistest.Run(t, dir, copylock.Analyzer, "golang.org/fake/forstmt")
}

func TestVersions21(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "src", "forstmt", "go21.txtar"))
	analysistest.Run(t, dir, copylock.Analyzer, "golang.org/fake/forstmt")
}


================================================
FILE: go/analysis/passes/copylock/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The copylock command applies the golang.org/x/tools/go/analysis/passes/copylock
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/copylock"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(copylock.Analyzer) }


================================================
FILE: go/analysis/passes/copylock/testdata/src/a/copylock.go
================================================
package a

import (
	"sync"
	"sync/atomic"
	"unsafe"
	. "unsafe"
	unsafe1 "unsafe"
)

func OkFunc() {
	var x *sync.Mutex
	p := x
	var y sync.Mutex
	p = &y

	var z = sync.Mutex{}
	w := sync.Mutex{}

	w = sync.Mutex{}
	q := struct{ L sync.Mutex }{
		L: sync.Mutex{},
	}

	yy := []Tlock{
		Tlock{},
		Tlock{
			once: sync.Once{},
		},
	}

	nl := new(sync.Mutex)
	mx := make([]sync.Mutex, 10)
	xx := struct{ L *sync.Mutex }{
		L: new(sync.Mutex),
	}

	var pz = (sync.Mutex{})
	pw := (sync.Mutex{})
}

type Tlock struct {
	once sync.Once
}

func BadFunc() {
	var x *sync.Mutex
	p := x
	var y sync.Mutex
	p = &y
	*p = *x // want `assignment copies lock value to \*p: sync.Mutex`

	var t Tlock
	var tp *Tlock
	tp = &t
	*tp = t // want `assignment copies lock value to \*tp: a.Tlock contains sync.Once contains sync\b.*`
	t = *tp // want `assignment copies lock value to t: a.Tlock contains sync.Once contains sync\b.*`

	y := *x   // want "assignment copies lock value to y: sync.Mutex"
	var z = t // want `variable declaration copies lock value to z: a.Tlock contains sync.Once contains sync\b.*`

	w := struct{ L sync.Mutex }{
		L: *x, // want `literal copies lock value from \*x: sync.Mutex`
	}
	var q = map[int]Tlock{
		1: t,   // want `literal copies lock value from t: a.Tlock contains sync.Once contains sync\b.*`
		2: *tp, // want `literal copies lock value from \*tp: a.Tlock contains sync.Once contains sync\b.*`
	}
	yy := []Tlock{
		t,   // want `literal copies lock value from t: a.Tlock contains sync.Once contains sync\b.*`
		*tp, // want `literal copies lock value from \*tp: a.Tlock contains sync.Once contains sync\b.*`
	}

	// override 'new' keyword
	new := func(interface{}) {}
	new(t) // want `call of new copies lock value: a.Tlock contains sync.Once contains sync\b.*`

	// copy of array of locks
	var muA [5]sync.Mutex
	muB := muA        // want "assignment copies lock value to muB: sync.Mutex"
	muA = muB         // want "assignment copies lock value to muA: sync.Mutex"
	muSlice := muA[:] // OK

	// multidimensional array
	var mmuA [5][5]sync.Mutex
	mmuB := mmuA        // want "assignment copies lock value to mmuB: sync.Mutex"
	mmuA = mmuB         // want "assignment copies lock value to mmuA: sync.Mutex"
	mmuSlice := mmuA[:] // OK

	// slice copy is ok
	var fmuA [5][][5]sync.Mutex
	fmuB := fmuA        // OK
	fmuA = fmuB         // OK
	fmuSlice := fmuA[:] // OK

	// map access by single and tuple copies prohibited
	type mut struct{ mu sync.Mutex }
	muM := map[string]mut{
		"a": mut{},
	}
	mumA := muM["a"]    // want "assignment copies lock value to mumA: a.mut contains sync.Mutex"
	mumB, _ := muM["a"] // want "assignment copies lock value to mumB: \\(a.mut, bool\\) contains a.mut contains sync.Mutex"
}

func LenAndCapOnLockArrays() {
	var a [5]sync.Mutex
	aLen := len(a) // OK
	aCap := cap(a) // OK

	// override 'len' and 'cap' keywords

	len := func(interface{}) {}
	len(a) // want "call of len copies lock value: sync.Mutex"

	cap := func(interface{}) {}
	cap(a) // want "call of cap copies lock value: sync.Mutex"
}

func SizeofMutex() {
	var mu sync.Mutex
	unsafe.Sizeof(mu)  // OK
	unsafe1.Sizeof(mu) // OK
	Sizeof(mu)         // OK
	unsafe := struct{ Sizeof func(interface{}) }{}
	unsafe.Sizeof(mu) // want "call of unsafe.Sizeof copies lock value: sync.Mutex"
	Sizeof := func(interface{}) {}
	Sizeof(mu) // want "call of Sizeof copies lock value: sync.Mutex"
}

func OffsetofMutex() {
	type T struct {
		f  int
		mu sync.Mutex
	}
	unsafe.Offsetof(T{}.mu) // OK
	unsafe := struct{ Offsetof func(interface{}) }{}
	unsafe.Offsetof(T{}.mu) // want "call of unsafe.Offsetof copies lock value: sync.Mutex"
}

func AlignofMutex() {
	type T struct {
		f  int
		mu sync.Mutex
	}
	unsafe.Alignof(T{}.mu) // OK
	unsafe := struct{ Alignof func(interface{}) }{}
	unsafe.Alignof(T{}.mu) // want "call of unsafe.Alignof copies lock value: sync.Mutex"
}

// SyncTypesCheck checks copying of sync.* types except sync.Mutex
func SyncTypesCheck() {
	// sync.RWMutex copying
	var rwmuX sync.RWMutex
	var rwmuXX = sync.RWMutex{}
	rwmuX1 := new(sync.RWMutex)
	rwmuY := rwmuX     // want "assignment copies lock value to rwmuY: sync.RWMutex"
	rwmuY = rwmuX      // want "assignment copies lock value to rwmuY: sync.RWMutex"
	var rwmuYY = rwmuX // want "variable declaration copies lock value to rwmuYY: sync.RWMutex"
	rwmuP := &rwmuX
	rwmuZ := &sync.RWMutex{}

	// sync.Cond copying
	var condX sync.Cond
	var condXX = sync.Cond{}
	condX1 := new(sync.Cond)
	condY := condX     // want "assignment copies lock value to condY: sync.Cond contains sync.noCopy"
	condY = condX      // want "assignment copies lock value to condY: sync.Cond contains sync.noCopy"
	var condYY = condX // want "variable declaration copies lock value to condYY: sync.Cond contains sync.noCopy"
	condP := &condX
	condZ := &sync.Cond{
		L: &sync.Mutex{},
	}
	condZ = sync.NewCond(&sync.Mutex{})

	// sync.WaitGroup copying
	var wgX sync.WaitGroup
	var wgXX = sync.WaitGroup{}
	wgX1 := new(sync.WaitGroup)
	wgY := wgX     // want "assignment copies lock value to wgY: sync.WaitGroup contains sync.noCopy"
	wgY = wgX      // want "assignment copies lock value to wgY: sync.WaitGroup contains sync.noCopy"
	var wgYY = wgX // want "variable declaration copies lock value to wgYY: sync.WaitGroup contains sync.noCopy"
	wgP := &wgX
	wgZ := &sync.WaitGroup{}

	// sync.Pool copying
	var poolX sync.Pool
	var poolXX = sync.Pool{}
	poolX1 := new(sync.Pool)
	poolY := poolX     // want "assignment copies lock value to poolY: sync.Pool contains sync.noCopy"
	poolY = poolX      // want "assignment copies lock value to poolY: sync.Pool contains sync.noCopy"
	var poolYY = poolX // want "variable declaration copies lock value to poolYY: sync.Pool contains sync.noCopy"
	poolP := &poolX
	poolZ := &sync.Pool{}

	// sync.Once copying
	var onceX sync.Once
	var onceXX = sync.Once{}
	onceX1 := new(sync.Once)
	onceY := onceX     // want `assignment copies lock value to onceY: sync.Once contains sync\b.*`
	onceY = onceX      // want `assignment copies lock value to onceY: sync.Once contains sync\b.*`
	var onceYY = onceX // want `variable declaration copies lock value to onceYY: sync.Once contains sync\b.*`
	onceP := &onceX
	onceZ := &sync.Once{}
}

// AtomicTypesCheck checks copying of sync/atomic types
func AtomicTypesCheck() {
	// atomic.Value copying
	var vX atomic.Value
	var vXX = atomic.Value{}
	vX1 := new(atomic.Value)
	// These are OK because the value has not been used yet.
	// (And vet can't tell whether it has been used, so they're always OK.)
	vY := vX
	vY = vX
	var vYY = vX
	vP := &vX
	vZ := &atomic.Value{}
}

// PointerRhsCheck checks that exceptions are made for pointer return values of
// function calls. These may be zero initialized so they are considered OK.
func PointerRhsCheck() {
	newMutex := func() *sync.Mutex { return new(sync.Mutex) }
	d := *newMutex()
	pd := *(newMutex())
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/a/copylock_func.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the copylock checker's
// function declaration analysis.

// There are two cases missing from this file which
// are located in the "unfortunate" package in the
// testdata directory. Once the go.mod >= 1.26 for this
// repository, merge local_go124.go back into this file.

package a

import "sync"

func OkFunc(*sync.Mutex) {}
func BadFunc(sync.Mutex) {} // want "BadFunc passes lock by value: sync.Mutex"
func BadFunc2(sync.Map)  {} // want "BadFunc2 passes lock by value: sync.Map contains sync.(Mutex|noCopy)"
func OkRet() *sync.Mutex {}
func BadRet() sync.Mutex {} // Don't warn about results

var (
	OkClosure   = func(*sync.Mutex) {}
	BadClosure  = func(sync.Mutex) {} // want "func passes lock by value: sync.Mutex"
	BadClosure2 = func(sync.Map) {}   // want "func passes lock by value: sync.Map contains sync.(Mutex|noCopy)"
)

type EmbeddedRWMutex struct {
	sync.RWMutex
}

func (*EmbeddedRWMutex) OkMeth() {}
func (EmbeddedRWMutex) BadMeth() {} // want "BadMeth passes lock by value: a.EmbeddedRWMutex"
func OkFunc(e *EmbeddedRWMutex)  {}
func BadFunc(EmbeddedRWMutex)    {} // want "BadFunc passes lock by value: a.EmbeddedRWMutex"
func OkRet() *EmbeddedRWMutex    {}
func BadRet() EmbeddedRWMutex    {} // Don't warn about results

type FieldMutex struct {
	s sync.Mutex
}

func (*FieldMutex) OkMeth()   {}
func (FieldMutex) BadMeth()   {} // want "BadMeth passes lock by value: a.FieldMutex contains sync.Mutex"
func OkFunc(*FieldMutex)      {}
func BadFunc(FieldMutex, int) {} // want "BadFunc passes lock by value: a.FieldMutex contains sync.Mutex"

type L0 struct {
	L1
}

type L1 struct {
	l L2
}

type L2 struct {
	sync.Mutex
}

func (*L0) Ok() {}
func (L0) Bad() {} // want "Bad passes lock by value: a.L0 contains a.L1 contains a.L2"

type EmbeddedMutexPointer struct {
	s *sync.Mutex // safe to copy this pointer
}

func (*EmbeddedMutexPointer) Ok()      {}
func (EmbeddedMutexPointer) AlsoOk()   {}
func StillOk(EmbeddedMutexPointer)     {}
func LookinGood() EmbeddedMutexPointer {}

type EmbeddedLocker struct {
	sync.Locker // safe to copy interface values
}

func (*EmbeddedLocker) Ok()    {}
func (EmbeddedLocker) AlsoOk() {}

type CustomLock struct{}

func (*CustomLock) Lock()   {}
func (*CustomLock) Unlock() {}

func Ok(*CustomLock) {}
func Bad(CustomLock) {} // want "Bad passes lock by value: a.CustomLock"

// Passing lock values into interface function arguments
func FuncCallInterfaceArg(f func(a int, b interface{})) {
	var m sync.Mutex
	var t struct{ lock sync.Mutex }

	f(1, "foo")
	f(2, &t)
	f(3, &sync.Mutex{})
	f(4, m) // want "call of f copies lock value: sync.Mutex"
	f(5, t) // want "call of f copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
	var fntab []func(t)
	fntab[0](t) // want "call of fntab.0. copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
}

// Returning lock via interface value
func ReturnViaInterface(x int) (int, interface{}) {
	var m sync.Mutex
	var t struct{ lock sync.Mutex }

	switch x % 4 {
	case 0:
		return 0, "qwe"
	case 1:
		return 1, &sync.Mutex{}
	case 2:
		return 2, m // want "return copies lock value: sync.Mutex"
	default:
		return 3, t // want "return copies lock value: struct.lock sync.Mutex. contains sync.Mutex"
	}
}

// Some cases that we don't warn about.

func AcceptedCases() {
	x := EmbeddedRwMutex{} // composite literal on RHS is OK (#16227)
	x = BadRet()           // function call on RHS is OK (#16227)
	x = *OKRet()           // indirection of function call on RHS is OK (#16227)
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/a/copylock_range.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the copylock checker's
// range statement analysis.

package a

import "sync"

func rangeMutex() {
	var mu sync.Mutex
	var i int

	var s []sync.Mutex
	for range s {
	}
	for i = range s {
	}
	for i := range s {
	}
	for i, _ = range s {
	}
	for i, _ := range s {
	}
	for _, mu = range s { // want "range var mu copies lock: sync.Mutex"
	}
	for _, m := range s { // want "range var m copies lock: sync.Mutex"
	}
	for i, mu = range s { // want "range var mu copies lock: sync.Mutex"
	}
	for i, m := range s { // want "range var m copies lock: sync.Mutex"
	}

	var a [3]sync.Mutex
	for _, m := range a { // want "range var m copies lock: sync.Mutex"
	}

	var m map[sync.Mutex]sync.Mutex
	for k := range m { // want "range var k copies lock: sync.Mutex"
	}
	for mu, _ = range m { // want "range var mu copies lock: sync.Mutex"
	}
	for k, _ := range m { // want "range var k copies lock: sync.Mutex"
	}
	for _, mu = range m { // want "range var mu copies lock: sync.Mutex"
	}
	for _, v := range m { // want "range var v copies lock: sync.Mutex"
	}

	var c chan sync.Mutex
	for range c {
	}
	for mu = range c { // want "range var mu copies lock: sync.Mutex"
	}
	for v := range c { // want "range var v copies lock: sync.Mutex"
	}

	// Test non-idents in range variables
	var t struct {
		i  int
		mu sync.Mutex
	}
	for t.i, t.mu = range s { // want "range var t.mu copies lock: sync.Mutex"
	}
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/a/issue61678.go
================================================
// This test relies on a compiler bug patched in Go 1.26.
//go:build !go1.26

package a

import "sync"

// These examples are taken from golang/go#61678, modified so that A and B
// contain a mutex.

type A struct {
	a  A
	mu sync.Mutex
}

type B struct {
	a  A
	b  B
	mu sync.Mutex
}

func okay(x A) {}
func sure()    { var x A; nop(x) }

var fine B

func what(x B)   {}                  // want `passes lock by value`
func bad()       { var x B; nop(x) } // want `copies lock value`
func good()      { nop(B{}) }
func stillgood() { nop(B{b: B{b: B{b: B{}}}}) }
func nope()      { nop(B{}.b) } // want `copies lock value`

func nop(any) {} // only used to get around unused variable errors


================================================
FILE: go/analysis/passes/copylock/testdata/src/a/newexpr_go126.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.26

package a

import "sync"

func _(ptr *sync.Mutex) {
	_ = new(sync.Mutex)
	_ = new(*ptr) // want `call of new copies lock value: sync.Mutex`
)


================================================
FILE: go/analysis/passes/copylock/testdata/src/forstmt/go21.txtar
================================================
Test copylock at go version go1.21.

-- go.mod --
module golang.org/fake/forstmt

go 1.21
-- pre.go --
//go:build go1.21

package forstmt

import "sync"

func InGo21(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {  // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ { // Not reported before 1.22.
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // Not reported before 1.22.
		_ = mu.TryLock()
	}
}
-- go22.go --
//go:build go1.22

package forstmt

import "sync"

func InGo22(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {  // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
}
-- modver.go --
package forstmt

import "sync"

func AtGo121ByModuleVersion(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {  // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ { // Not reported before 1.22.
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // Not reported before 1.22.
		_ = mu.TryLock()
	}
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/forstmt/go22.txtar
================================================
Test copylock at go version go1.22.

-- go.mod --
module golang.org/fake/forstmt

go 1.22
-- pre.go --
//go:build go1.21

package forstmt

import "sync"

func InGo21(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {   // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported before 1.22.
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // Not reported before 1.22.
		_ = mu.TryLock()
	}
}
-- go22.go --
//go:build go1.22

package forstmt

import "sync"

func InGo22(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {  // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
}
-- modver.go --
package forstmt

import "sync"

func InGo22ByModuleVersion(l []int) {
	var mu sync.Mutex
	var x int

	for x, mu = 0, (sync.Mutex{}); x < 10; x++ {  // Not reported on '='.
	}
	for x, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
	for x, _ := 0, (sync.Mutex{}); x < 10; x++ {  // Not reported due to '_'.
		_ = mu.TryLock()
	}
	for _, mu := 0, (sync.Mutex{}); x < 10; x++ { // want "for loop iteration copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
}
-- assign.go --
//go:build go1.22

package forstmt

import "sync"

func ReportAssign(l []int) {
	// Test we do not report a duplicate if the assignment is reported.
	var mu sync.Mutex
	for x, mu := 0, mu; x < 10; x++ { // want "assignment copies lock value to mu: sync.Mutex"
		_ = mu.TryLock()
	}
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/issue67787/issue67787.go
================================================
package issue67787

import "sync"

type T struct{ mu sync.Mutex }
type T1 struct{ t *T }

func NewT1() *T1 { return &T1{T} } // no analyzer diagnostic about T


================================================
FILE: go/analysis/passes/copylock/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "sync"

// The copylock analyzer runs despite errors. The following invalid type should
// not cause an infinite recursion.
type R struct{ r R }

func TestNoRecursion(r R) {}

// The following recursive type parameter definitions should not cause an
// infinite recursion.
func TestNoTypeParamRecursion[T1 ~[]T2, T2 ~[]T1 | string, T3 ~struct{ F T3 }](t1 T1, t2 T2, t3 T3) {
}

func OkFunc1[Struct ~*struct{ mu sync.Mutex }](s Struct) {
}

func BadFunc1[Struct ~struct{ mu sync.Mutex }](s Struct) { // want `passes lock by value: .*Struct contains ~struct{mu sync.Mutex}`
}

func OkFunc2[MutexPtr *sync.Mutex](m MutexPtr) {
	var x *MutexPtr
	p := x
	var y MutexPtr
	p = &y
	*p = *x

	var mus []MutexPtr

	for _, _ = range mus {
	}
}

func BadFunc2[Mutex sync.Mutex](m Mutex) { // want `passes lock by value: .*Mutex contains sync.Mutex`
	var x *Mutex
	p := x
	var y Mutex
	p = &y
	*p = *x // want `assignment copies lock value to \*p: .*Mutex contains sync.Mutex`

	var mus []Mutex

	for _, _ = range mus {
	}
}

func ApproximationError[Mutex interface {
	~sync.Mutex
	M()
}](m Mutex) { // want `passes lock by value: .*Mutex contains ~sync.Mutex`
}


================================================
FILE: go/analysis/passes/copylock/testdata/src/unfortunate/local_go123.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.24

package unfortunate

import "sync"

// TODO: Unfortunate cases

// Non-ideal error message:
// Since we're looking for Lock methods, sync.Once's underlying
// sync.Mutex gets called out, but without any reference to the sync.Once.
type LocalOnce sync.Once

func (LocalOnce) Bad() {} // want `Bad passes lock by value: unfortunate.LocalOnce contains sync.\b.*`

// False negative:
// LocalMutex doesn't have a Lock method.
// Nevertheless, it is probably a bad idea to pass it by value.
type LocalMutex sync.Mutex

func (LocalMutex) Bad() {} // WANTED: An error here :(


================================================
FILE: go/analysis/passes/copylock/testdata/src/unfortunate/local_go124.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.24

package unfortunate

import "sync"

// Cases where the interior sync.noCopy shows through.

type LocalOnce sync.Once

func (LocalOnce) Bad() {} // want "Bad passes lock by value: unfortunate.LocalOnce contains sync.noCopy"

type LocalMutex sync.Mutex

func (LocalMutex) Bad() {} // want "Bad passes lock by value: unfortunate.LocalMutex contains sync.noCopy"


================================================
FILE: go/analysis/passes/ctrlflow/ctrlflow.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package ctrlflow is an analysis that provides a syntactic
// control-flow graph (CFG) for the body of a function.
// It records whether a function cannot return.
// By itself, it does not report any diagnostics.
package ctrlflow

import (
	"go/ast"
	"go/types"
	"log"
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/cfg"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

var Analyzer = &analysis.Analyzer{
	Name:       "ctrlflow",
	Doc:        "build a control-flow graph",
	URL:        "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/ctrlflow",
	Run:        run,
	ResultType: reflect.TypeFor[*CFGs](),
	FactTypes:  []analysis.Fact{new(noReturn)},
	Requires:   []*analysis.Analyzer{inspect.Analyzer},
}

// noReturn is a fact indicating that a function does not return.
type noReturn struct{}

func (*noReturn) AFact() {}

func (*noReturn) String() string { return "noReturn" }

// A CFGs holds the control-flow graphs
// for all the functions of the current package.
type CFGs struct {
	defs      map[*ast.Ident]types.Object // from Pass.TypesInfo.Defs
	funcDecls map[*types.Func]*declInfo
	funcLits  map[*ast.FuncLit]*litInfo
	noReturn  map[*types.Func]bool // functions lacking a reachable return statement
	pass      *analysis.Pass       // transient; nil after construction
}

// NoReturn reports whether the specified control-flow graph cannot return normally.
//
// It is defined for at least all function symbols that appear as the static callee of a
// CallExpr in the current package, even if the callee was imported from a dependency.
//
// The result may incorporate interprocedural information based on induction of
// the "no return" property over the static call graph within the package.
// For example, if f simply calls g and g always calls os.Exit, then both f and g may
// be deemed never to return.
func (c *CFGs) NoReturn(fn *types.Func) bool {
	return c.noReturn[fn]
}

// CFGs has two maps: funcDecls for named functions and funcLits for
// unnamed ones. Unlike funcLits, the funcDecls map is not keyed by its
// syntax node, *ast.FuncDecl, because callMayReturn needs to do a
// look-up by *types.Func, and you can get from an *ast.FuncDecl to a
// *types.Func but not the other way.

type declInfo struct {
	decl    *ast.FuncDecl
	cfg     *cfg.CFG // iff decl.Body != nil
	started bool     // to break cycles
}

type litInfo struct {
	cfg      *cfg.CFG
	noReturn bool // (currently unused)
}

// FuncDecl returns the control-flow graph for a named function.
// It returns nil if decl.Body==nil.
func (c *CFGs) FuncDecl(decl *ast.FuncDecl) *cfg.CFG {
	if decl.Body == nil {
		return nil
	}
	fn := c.defs[decl.Name].(*types.Func)
	return c.funcDecls[fn].cfg
}

// FuncLit returns the control-flow graph for a literal function.
func (c *CFGs) FuncLit(lit *ast.FuncLit) *cfg.CFG {
	return c.funcLits[lit].cfg
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// Because CFG construction consumes and produces noReturn
	// facts, CFGs for exported FuncDecls must be built before 'run'
	// returns; we cannot construct them lazily.
	// (We could build CFGs for FuncLits lazily,
	// but the benefit is marginal.)

	// Pass 1. Map types.Funcs to ast.FuncDecls in this package.
	funcDecls := make(map[*types.Func]*declInfo) // functions and methods
	funcLits := make(map[*ast.FuncLit]*litInfo)

	var decls []*types.Func // keys(funcDecls), in order
	var lits []*ast.FuncLit // keys(funcLits), in order

	nodeFilter := []ast.Node{
		(*ast.FuncDecl)(nil),
		(*ast.FuncLit)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.FuncDecl:
			// Type information may be incomplete.
			if fn, ok := pass.TypesInfo.Defs[n.Name].(*types.Func); ok {
				funcDecls[fn] = &declInfo{decl: n}
				decls = append(decls, fn)
			}
		case *ast.FuncLit:
			funcLits[n] = new(litInfo)
			lits = append(lits, n)
		}
	})

	c := &CFGs{
		defs:      pass.TypesInfo.Defs,
		funcDecls: funcDecls,
		funcLits:  funcLits,
		noReturn:  make(map[*types.Func]bool),
		pass:      pass,
	}

	// Pass 2. Build CFGs.

	// Build CFGs for named functions.
	// Cycles in the static call graph are broken
	// arbitrarily but deterministically.
	// We create noReturn facts as discovered.
	for _, fn := range decls {
		c.buildDecl(fn, funcDecls[fn])
	}

	// Build CFGs for literal functions.
	// These aren't relevant to facts (since they aren't named)
	// but are required for the CFGs.FuncLit API.
	for _, lit := range lits {
		li := funcLits[lit]
		if li.cfg == nil {
			li.cfg = cfg.New(lit.Body, c.callMayReturn)
			if li.cfg.NoReturn() {
				li.noReturn = true
			}
		}
	}

	// All CFGs are now built.
	c.pass = nil

	return c, nil
}

// di.cfg may be nil on return.
func (c *CFGs) buildDecl(fn *types.Func, di *declInfo) {
	// buildDecl may call itself recursively for the same function,
	// because cfg.New is passed the callMayReturn method, which
	// builds the CFG of the callee, leading to recursion.
	// The buildDecl call tree thus resembles the static call graph.
	// We mark each node when we start working on it to break cycles.

	if di.started {
		return // break cycle
	}
	di.started = true

	noreturn, known := knownIntrinsic(fn)
	if !known {
		if di.decl.Body != nil {
			di.cfg = cfg.New(di.decl.Body, c.callMayReturn)
			if di.cfg.NoReturn() {
				noreturn = true
			}
		}
	}
	if noreturn {
		c.pass.ExportObjectFact(fn, new(noReturn))
		c.noReturn[fn] = true
	}

	// debugging
	if false {
		log.Printf("CFG for %s:\n%s (noreturn=%t)\n", fn, di.cfg.Format(c.pass.Fset), noreturn)
	}
}

// callMayReturn reports whether the called function may return.
// It is passed to the CFG builder.
func (c *CFGs) callMayReturn(call *ast.CallExpr) (r bool) {
	if id, ok := call.Fun.(*ast.Ident); ok && c.pass.TypesInfo.Uses[id] == panicBuiltin {
		return false // panic never returns
	}

	// Is this a static call? Also includes static functions
	// parameterized by a type. Such functions may or may not
	// return depending on the parameter type, but in some
	// cases the answer is definite. We let ctrlflow figure
	// that out.
	fn := typeutil.StaticCallee(c.pass.TypesInfo, call)
	if fn == nil {
		return true // callee not statically known; be conservative
	}

	// Function or method declared in this package?
	if di, ok := c.funcDecls[fn]; ok {
		c.buildDecl(fn, di)
		return !c.noReturn[fn]
	}

	// Not declared in this package.
	// Is there a fact from another package?
	if c.pass.ImportObjectFact(fn, new(noReturn)) {
		c.noReturn[fn] = true
		return false
	}

	return true
}

var panicBuiltin = types.Universe.Lookup("panic").(*types.Builtin)

// knownIntrinsic reports whether a function intrinsically never
// returns because it stops execution of the calling thread, or does
// in fact return, contrary to its apparent body, because it is
// handled specially by the compiler.
//
// It is the base case in the recursion.
func knownIntrinsic(fn *types.Func) (noreturn, known bool) {
	// Add functions here as the need arises, but don't allocate memory.

	// Functions known intrinsically never to return.
	if typesinternal.IsFunctionNamed(fn, "syscall", "Exit", "ExitProcess", "ExitThread") ||
		typesinternal.IsFunctionNamed(fn, "runtime", "Goexit", "fatalthrow", "fatalpanic", "exit") ||
		// Following staticcheck (see go/ir/exits.go) we include functions
		// in several popular logging packages whose no-return status is
		// beyond the analysis to infer.
		// TODO(adonovan): make this list extensible.
		typesinternal.IsMethodNamed(fn, "go.uber.org/zap", "Logger", "Fatal", "Panic") ||
		typesinternal.IsMethodNamed(fn, "go.uber.org/zap", "SugaredLogger", "Fatal", "Fatalw", "Fatalf", "Panic", "Panicw", "Panicf") ||
		typesinternal.IsMethodNamed(fn, "github.com/sirupsen/logrus", "Logger", "Exit", "Panic", "Panicf", "Panicln") ||
		typesinternal.IsMethodNamed(fn, "github.com/sirupsen/logrus", "Entry", "Panicf", "Panicln") ||
		typesinternal.IsFunctionNamed(fn, "k8s.io/klog", "Exit", "ExitDepth", "Exitf", "Exitln", "Fatal", "FatalDepth", "Fatalf", "Fatalln") ||
		typesinternal.IsFunctionNamed(fn, "k8s.io/klog/v2", "Exit", "ExitDepth", "Exitf", "Exitln", "Fatal", "FatalDepth", "Fatalf", "Fatalln") {
		return true, true
	}

	// Compiler intrinsics known to return, contrary to
	// what analysis of the function body would conclude.
	//
	// Not all such intrinsics must be listed here: ctrlflow
	// considers any function called for its value--such as
	// crypto/internal/constanttime.bool2Uint8--to potentially
	// return; only functions called as a statement, for effects,
	// are no-return candidates.
	//
	// Unfortunately this does sometimes mean peering into internals.
	// Where possible, use the nearest enclosing public API function.
	if typesinternal.IsFunctionNamed(fn, "internal/abi", "EscapeNonString") ||
		typesinternal.IsFunctionNamed(fn, "hash/maphash", "Comparable") {
		return false, true
	}

	return // unknown
}


================================================
FILE: go/analysis/passes/ctrlflow/ctrlflow_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ctrlflow_test

import (
	"go/ast"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/ctrlflow"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	results := analysistest.Run(t, testdata, ctrlflow.Analyzer, "a", "typeparams")

	// Perform a minimal smoke test on
	// the result (CFG) computed by ctrlflow.
	for _, result := range results {
		cfgs := result.Result.(*ctrlflow.CFGs)

		for _, decl := range result.Action.Package.Syntax[0].Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok && decl.Body != nil {
				if cfgs.FuncDecl(decl) == nil {
					t.Errorf("%s: no CFG for func %s",
						result.Action.Package.Fset.Position(decl.Pos()), decl.Name.Name)
				}
			}
		}
	}
}


================================================
FILE: go/analysis/passes/ctrlflow/testdata/src/a/a.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

// This file tests facts produced by ctrlflow.

import (
	"hash/maphash"
	"log"
	"os"
	"runtime"
	"syscall"
	"testing"

	"lib"
)

var cond bool

func a() { // want a:"noReturn"
	if cond {
		b()
	} else {
		for {
		}
	}
}

func b() { // want b:"noReturn"
	select {}
}

func f(x int) { // no fact here
	switch x {
	case 0:
		os.Exit(0)
	case 1:
		panic(0)
	}
	// default case returns
}

type T int

func (T) method1() { // want method1:"noReturn"
	a()
}

func (T) method2() { // (may return)
	if cond {
		a()
	}
}

// Checking for the noreturn fact associated with F ensures that
// ctrlflow proved each of the listed functions was "noReturn".
func standardFunctions(x int) { // want standardFunctions:"noReturn"
	t := new(testing.T)
	switch x {
	case 0:
		t.FailNow()
	case 1:
		t.Fatal()
	case 2:
		t.Fatalf("")
	case 3:
		t.Skip()
	case 4:
		t.SkipNow()
	case 5:
		t.Skipf("")
	case 6:
		log.Fatal()
	case 7:
		log.Fatalf("")
	case 8:
		log.Fatalln()
	case 9:
		os.Exit(0)
	case 10:
		syscall.Exit(0)
	case 11:
		runtime.Goexit()
	case 12:
		log.Panic()
	case 13:
		log.Panicln()
	case 14:
		log.Panicf("")
	default:
		panic(0)
	}
}

func panicRecover() {
	defer func() { recover() }()
	panic(nil)
}

func noBody()

func g() {
	lib.CanReturn()
}

func h() { // want h:"noReturn"
	lib.NoReturn()
}

func returns() {
	print(1)
	print(2)
	print(3)
}

func nobody() // a function with no body is assumed to return

func hasPanic() { // want hasPanic:"noReturn"
	print(1)
	panic(2)
	print(3)
}

func hasSelect() { // want hasSelect:"noReturn"
	print(1)
	select {}
	print(3)
}

func infiniteLoop() { // want infiniteLoop:"noReturn"
	print(1)
	for {
	}
	print(3)
}

func ifElse(cond bool) { // want ifElse:"noReturn"
	print(1)
	if cond {
		hasSelect()
	} else {
		infiniteLoop()
	}
	print(3)
}

func swtch(x int) { // want swtch:"noReturn"
	print(1)
	switch x {
	case 1:
		hasSelect()
	case 2:
		goexit()
	case 3:
		logFatal()
	case 4:
		osexit()
	default:
		panic(3)
	}
}

func _if(cond bool) {
	print(1)
	if cond {
		hasSelect()
	}
	print(3)
}

func logFatal() { // want logFatal:"noReturn"
	print(1)
	log.Fatal("oops")
	print(2)
}

func testFatal(t *testing.T) { // want testFatal:"noReturn"
	print(1)
	t.Fatal("oops")
	print(2)
}

func goexit() { // want goexit:"noReturn"
	print(1)
	runtime.Goexit()
	print(2)
}

func osexit() { // want osexit:"noReturn"
	print(1)
	os.Exit(0)
	print(2)
}

func intrinsic() { // (no fact)

	// Comparable calls abi.EscapeNonString, whose body appears to panic;
	// but that's a lie, as EscapeNonString is a compiler intrinsic.
	// (go1.24 used a different intrinsic, maphash.escapeForHash.)
	maphash.Comparable[int](maphash.Seed{}, 0)
}


================================================
FILE: go/analysis/passes/ctrlflow/testdata/src/lib/lib.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lib

func CanReturn() {}

func NoReturn() {
	for {
	}
}


================================================
FILE: go/analysis/passes/ctrlflow/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

// This file tests facts produced by ctrlflow.

var cond bool

var funcs = []func(){func() {}}

func a[A any]() { // want a:"noReturn"
	if cond {
		funcs[0]()
		b[A]()
	} else {
		for {
		}
	}
}

func b[B any]() { // want b:"noReturn"
	select {}
}

func c[A, B any]() { // want c:"noReturn"
	if cond {
		a[A]()
	} else {
		d[A, B]()
	}
}

func d[A, B any]() { // want d:"noReturn"
	b[B]()
}

type I[T any] interface {
	Id(T) T
}

func e[T any](i I[T], t T) T {
	return i.Id(t)
}

func k[T any](i I[T], t T) T { // want k:"noReturn"
	b[T]()
	return i.Id(t)
}

type T[X any] int

func (T[X]) method1() { // want method1:"noReturn"
	a[X]()
}

func (T[X]) method2() { // (may return)
	if cond {
		a[X]()
	} else {
		funcs[0]()
	}
}


================================================
FILE: go/analysis/passes/deepequalerrors/deepequalerrors.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package deepequalerrors defines an Analyzer that checks for the use
// of reflect.DeepEqual with error values.
package deepequalerrors

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = `check for calls of reflect.DeepEqual on error values

The deepequalerrors checker looks for calls of the form:

    reflect.DeepEqual(err1, err2)

where err1 and err2 are errors. Using reflect.DeepEqual to compare
errors is discouraged.`

var Analyzer = &analysis.Analyzer{
	Name:     "deepequalerrors",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/deepequalerrors",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "reflect") {
		return nil, nil // doesn't directly import reflect
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		obj := typeutil.Callee(pass.TypesInfo, call)
		if typesinternal.IsFunctionNamed(obj, "reflect", "DeepEqual") && hasError(pass, call.Args[0]) && hasError(pass, call.Args[1]) {
			pass.ReportRangef(call, "avoid using reflect.DeepEqual with errors")
		}
	})
	return nil, nil
}

var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

// hasError reports whether the type of e contains the type error.
// See containsError, below, for the meaning of "contains".
func hasError(pass *analysis.Pass, e ast.Expr) bool {
	tv, ok := pass.TypesInfo.Types[e]
	if !ok { // no type info, assume good
		return false
	}
	return containsError(tv.Type)
}

// Report whether any type that typ could store and that could be compared is the
// error type. This includes typ itself, as well as the types of struct field, slice
// and array elements, map keys and elements, and pointers. It does not include
// channel types (incomparable), arg and result types of a Signature (not stored), or
// methods of a named or interface type (not stored).
func containsError(typ types.Type) bool {
	// Track types being processed, to avoid infinite recursion.
	// Using types as keys here is OK because we are checking for the identical pointer, not
	// type identity. See analysis/passes/printf/types.go.
	inProgress := make(map[types.Type]bool)

	var check func(t types.Type) bool
	check = func(t types.Type) bool {
		if t == errorType {
			return true
		}
		if inProgress[t] {
			return false
		}
		inProgress[t] = true
		switch t := t.(type) {
		case *types.Pointer:
			return check(t.Elem())
		case *types.Slice:
			return check(t.Elem())
		case *types.Array:
			return check(t.Elem())
		case *types.Map:
			return check(t.Key()) || check(t.Elem())
		case *types.Struct:
			for field := range t.Fields() {
				if check(field.Type()) {
					return true
				}
			}
		case *types.Named, *types.Alias:
			return check(t.Underlying())

		// We list the remaining valid type kinds for completeness.
		case *types.Basic:
		case *types.Chan: // channels store values, but they are not comparable
		case *types.Signature:
		case *types.Tuple: // tuples are only part of signatures
		case *types.Interface:
		}
		return false
	}

	return check(typ)
}


================================================
FILE: go/analysis/passes/deepequalerrors/deepequalerrors_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package deepequalerrors_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/deepequalerrors"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, deepequalerrors.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/deepequalerrors/testdata/src/a/a.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the deepequalerrors checker.

package a

import (
	"io"
	"os"
	"reflect"
)

type myError int

func (myError) Error() string { return "" }

func bad() error { return nil }

type s1 struct {
	s2 *s2
	i  int
}

type myError2 error

type s2 struct {
	s1   *s1
	errs []*myError2
}

func hasError() {
	var e error
	var m myError2
	reflect.DeepEqual(bad(), e)           // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(io.EOF, io.EOF)     // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, &e)              // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, m)               // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, s1{})            // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, [1]error{})      // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, map[error]int{}) // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, map[int]error{}) // want `avoid using reflect.DeepEqual with errors`
	// We catch the next not because *os.PathError implements error, but because it contains
	// a field Err of type error.
	reflect.DeepEqual(&os.PathError{}, io.EOF) // want `avoid using reflect.DeepEqual with errors`

}

func notHasError() {
	reflect.ValueOf(4)                    // not reflect.DeepEqual
	reflect.DeepEqual(3, 4)               // not errors
	reflect.DeepEqual(5, io.EOF)          // only one error
	reflect.DeepEqual(myError(1), io.EOF) // not types that implement error
}


================================================
FILE: go/analysis/passes/deepequalerrors/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the deepequalerrors checker.

package a

import (
	"io"
	"os"
	"reflect"
)

type myError int

func (myError) Error() string { return "" }

func bad[T any]() T {
	var t T
	return t
}

type s1 struct {
	s2 *s2[myError2]
	i  int
}

type myError2 error

type s2[T any] struct {
	s1   *s1
	errs []*T
}

func hasError() {
	var e error
	var m myError2
	reflect.DeepEqual(bad[error](), e)    // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(io.EOF, io.EOF)     // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, &e)              // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, m)               // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, s1{})            // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, [1]error{})      // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, map[error]int{}) // want `avoid using reflect.DeepEqual with errors`
	reflect.DeepEqual(e, map[int]error{}) // want `avoid using reflect.DeepEqual with errors`
	// We catch the next not because *os.PathError implements error, but because it contains
	// a field Err of type error.
	reflect.DeepEqual(&os.PathError{}, io.EOF) // want `avoid using reflect.DeepEqual with errors`

}

func notHasError() {
	reflect.ValueOf(4)                    // not reflect.DeepEqual
	reflect.DeepEqual(3, 4)               // not errors
	reflect.DeepEqual(5, io.EOF)          // only one error
	reflect.DeepEqual(myError(1), io.EOF) // not types that implement error
}


================================================
FILE: go/analysis/passes/defers/cmd/defers/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The defers command runs the defers analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/defers"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(defers.Analyzer) }


================================================
FILE: go/analysis/passes/defers/defers.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package defers

import (
	_ "embed"
	"go/ast"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

// Analyzer is the defers analyzer.
var Analyzer = &analysis.Analyzer{
	Name:     "defers",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Doc:      analyzerutil.MustExtractDoc(doc, "defers"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/defers",
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "time") {
		return nil, nil
	}

	checkDeferCall := func(node ast.Node) bool {
		switch v := node.(type) {
		case *ast.CallExpr:
			if typesinternal.IsFunctionNamed(typeutil.Callee(pass.TypesInfo, v), "time", "Since") {
				pass.Reportf(v.Pos(), "call to time.Since is not deferred")
			}
		case *ast.FuncLit:
			return false // prune
		}
		return true
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.DeferStmt)(nil),
	}

	inspect.Preorder(nodeFilter, func(n ast.Node) {
		d := n.(*ast.DeferStmt)
		ast.Inspect(d.Call, checkDeferCall)
	})

	return nil, nil
}


================================================
FILE: go/analysis/passes/defers/defers_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package defers_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/defers"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, defers.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/defers/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package defers defines an Analyzer that checks for common mistakes in defer
// statements.
//
// # Analyzer defers
//
// defers: report common mistakes in defer statements
//
// The defers analyzer reports a diagnostic when a defer statement would
// result in a non-deferred call to time.Since, as experience has shown
// that this is nearly always a mistake.
//
// For example:
//
//	start := time.Now()
//	...
//	defer recordLatency(time.Since(start)) // error: call to time.Since is not deferred
//
// The correct code is:
//
//	defer func() { recordLatency(time.Since(start)) }()
package defers


================================================
FILE: go/analysis/passes/defers/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"fmt"
	"time"
)

func Since() (t time.Duration) {
	return
}

func x(time.Duration) {}
func x2(float64)      {}

func good() {
	// The following are OK because func is not evaluated in defer invocation.
	now := time.Now()
	defer func() {
		fmt.Println(time.Since(now)) // OK because time.Since is not evaluated in defer
	}()
	evalBefore := time.Since(now)
	defer fmt.Println(evalBefore)
	do := func(f func()) {}
	defer do(func() { time.Since(now) })
	defer fmt.Println(Since())       // OK because Since function is not in module time
	defer copy([]int(nil), []int{1}) // check that a builtin doesn't cause a panic
}

type y struct{}

func (y) A(float64)        {}
func (*y) B(float64)       {}
func (y) C(time.Duration)  {}
func (*y) D(time.Duration) {}

func bad() {
	var zero time.Time
	now := time.Now()
	defer time.Since(zero)                    // want "call to time.Since is not deferred"
	defer time.Since(now)                     // want "call to time.Since is not deferred"
	defer fmt.Println(time.Since(now))        // want "call to time.Since is not deferred"
	defer fmt.Println(time.Since(time.Now())) // want "call to time.Since is not deferred"
	defer x(time.Since(now))                  // want "call to time.Since is not deferred"
	defer x2(time.Since(now).Seconds())       // want "call to time.Since is not deferred"
	defer y{}.A(time.Since(now).Seconds())    // want "call to time.Since is not deferred"
	defer (&y{}).B(time.Since(now).Seconds()) // want "call to time.Since is not deferred"
	defer y{}.C(time.Since(now))              // want "call to time.Since is not deferred"
	defer (&y{}).D(time.Since(now))           // want "call to time.Since is not deferred"
}

func ugly() {
	// The following is ok even though time.Since is evaluated. We don't
	// walk into function literals or check what function definitions are doing.
	defer x((func() time.Duration { return time.Since(time.Now()) })())
}


================================================
FILE: go/analysis/passes/directive/directive.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package directive defines an Analyzer that checks known Go toolchain directives.
package directive

import (
	"go/ast"
	"go/parser"
	"go/token"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

const Doc = `check Go toolchain directives such as //go:debug

This analyzer checks for problems with known Go toolchain directives
in all Go source files in a package directory, even those excluded by
//go:build constraints, and all non-Go source files too.

For //go:debug (see https://go.dev/doc/godebug), the analyzer checks
that the directives are placed only in Go source files, only above the
package comment, and only in package main or *_test.go files.

Support for other known directives may be added in the future.

This analyzer does not check //go:build, which is handled by the
buildtag analyzer.
`

var Analyzer = &analysis.Analyzer{
	Name: "directive",
	Doc:  Doc,
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/directive",
	Run:  runDirective,
}

func runDirective(pass *analysis.Pass) (any, error) {
	for _, f := range pass.Files {
		checkGoFile(pass, f)
	}
	for _, name := range pass.OtherFiles {
		if err := checkOtherFile(pass, name); err != nil {
			return nil, err
		}
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments)
			if err != nil {
				// Not valid Go source code - not our job to diagnose, so ignore.
				continue
			}
			checkGoFile(pass, f)
		} else {
			if err := checkOtherFile(pass, name); err != nil {
				return nil, err
			}
		}
	}
	return nil, nil
}

func checkGoFile(pass *analysis.Pass, f *ast.File) {
	check := newChecker(pass, pass.Fset.File(f.Package).Name(), f)

	for _, group := range f.Comments {
		// A //go:build or a //go:debug comment is ignored after the package declaration
		// (but adjoining it is OK, in contrast to +build comments).
		if group.Pos() >= f.Package {
			check.inHeader = false
		}

		// Check each line of a //-comment.
		for _, c := range group.List {
			check.comment(c.Slash, c.Text)
		}
	}
}

func checkOtherFile(pass *analysis.Pass, filename string) error {
	// We cannot use the Go parser, since is not a Go source file.
	// Read the raw bytes instead.
	content, tf, err := analyzerutil.ReadFile(pass, filename)
	if err != nil {
		return err
	}

	check := newChecker(pass, filename, nil)
	check.nonGoFile(token.Pos(tf.Base()), string(content))
	return nil
}

type checker struct {
	pass     *analysis.Pass
	filename string
	file     *ast.File // nil for non-Go file
	inHeader bool      // in file header (before or adjoining package declaration)
}

func newChecker(pass *analysis.Pass, filename string, file *ast.File) *checker {
	return &checker{
		pass:     pass,
		filename: filename,
		file:     file,
		inHeader: true,
	}
}

func (check *checker) nonGoFile(pos token.Pos, fullText string) {
	// Process each line.
	text := fullText
	inStar := false
	for text != "" {
		offset := len(fullText) - len(text)
		var line string
		line, text, _ = strings.Cut(text, "\n")

		if !inStar && strings.HasPrefix(line, "//") {
			check.comment(pos+token.Pos(offset), line)
			continue
		}

		// Skip over, cut out any /* */ comments,
		// to avoid being confused by a commented-out // comment.
		for {
			line = strings.TrimSpace(line)
			if inStar {
				var ok bool
				_, line, ok = strings.Cut(line, "*/")
				if !ok {
					break
				}
				inStar = false
				continue
			}
			line, inStar = stringsCutPrefix(line, "/*")
			if !inStar {
				break
			}
		}
		if line != "" {
			// Found non-comment non-blank line.
			// Ends space for valid //go:build comments,
			// but also ends the fraction of the file we can
			// reliably parse. From this point on we might
			// incorrectly flag "comments" inside multiline
			// string constants or anything else (this might
			// not even be a Go program). So stop.
			break
		}
	}
}

func (check *checker) comment(pos token.Pos, line string) {
	if !strings.HasPrefix(line, "//go:") {
		return
	}
	// testing hack: stop at // ERROR
	if i := strings.Index(line, " // ERROR "); i >= 0 {
		line = line[:i]
	}

	verb := line
	if i := strings.IndexFunc(verb, unicode.IsSpace); i >= 0 {
		verb = verb[:i]
		if line[i] != ' ' && line[i] != '\t' && line[i] != '\n' {
			r, _ := utf8.DecodeRuneInString(line[i:])
			check.pass.Reportf(pos, "invalid space %#q in %s directive", r, verb)
		}
	}

	switch verb {
	default:
		// TODO: Use the go language version for the file.
		// If that version is not newer than us, then we can
		// report unknown directives.

	case "//go:build":
		// Ignore. The buildtag analyzer reports misplaced comments.

	case "//go:debug":
		if check.file == nil {
			check.pass.Reportf(pos, "//go:debug directive only valid in Go source files")
		} else if check.file.Name.Name != "main" && !strings.HasSuffix(check.filename, "_test.go") {
			check.pass.Reportf(pos, "//go:debug directive only valid in package main or test")
		} else if !check.inHeader {
			check.pass.Reportf(pos, "//go:debug directive only valid before package declaration")
		}
	}
}

// Go 1.20 strings.CutPrefix.
func stringsCutPrefix(s, prefix string) (after string, found bool) {
	if !strings.HasPrefix(s, prefix) {
		return s, false
	}
	return s[len(prefix):], true
}


================================================
FILE: go/analysis/passes/directive/directive_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package directive_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/directive"
)

func Test(t *testing.T) {
	// This test has a dedicated hack in the analysistest package:
	// Because it cares about IgnoredFiles, which most analyzers
	// ignore, the test framework will consider expectations in
	// ignore files too, but only for this analyzer.
	analysistest.Run(t, analysistest.TestData(), directive.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/directive/testdata/src/a/badspace.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// want +1 `invalid space '\\u00a0' in //go:debug directive`
//go:debug 00a0

package main



================================================
FILE: go/analysis/passes/directive/testdata/src/a/issue66046.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

//go:debug panicnil=1
package main


================================================
FILE: go/analysis/passes/directive/testdata/src/a/misplaced.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

package main

// want +1 `//go:debug directive only valid before package declaration`
//go:debug panicnil=1


================================================
FILE: go/analysis/passes/directive/testdata/src/a/misplaced.s
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `//go:debug directive only valid in Go source files`
//go:debug panicnil=1

/*
can skip over comments
//go:debug doesn't matter here
*/

// want +1 `//go:debug directive only valid in Go source files`
//go:debug panicnil=1

package a

// no error here because we can't parse this far
//go:debug panicnil=1


================================================
FILE: go/analysis/passes/directive/testdata/src/a/misplaced_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:debug panicnil=1

package p_test

// want +1 `//go:debug directive only valid before package declaration`
//go:debug panicnil=1


================================================
FILE: go/analysis/passes/directive/testdata/src/a/p.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// want +1 `//go:debug directive only valid in package main or test`
//go:debug panicnil=1

package p

// want +1 `//go:debug directive only valid in package main or test`
//go:debug panicnil=1


================================================
FILE: go/analysis/passes/errorsas/errorsas.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The errorsas package defines an Analyzer that checks that the second argument to
// errors.As is a pointer to a type implementing error.
package errorsas

import (
	"errors"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

const Doc = `report passing non-pointer or non-error values to errors.As

The errorsas analyzer reports calls to errors.As where the type
of the second argument is not a pointer to a type implementing error.`

var Analyzer = &analysis.Analyzer{
	Name:     "errorsas",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/errorsas",
	Requires: []*analysis.Analyzer{typeindexanalyzer.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	switch pass.Pkg.Path() {
	case "errors", "errors_test":
		// These packages know how to use their own APIs.
		// Sometimes they are testing what happens to incorrect programs.
		return nil, nil
	}

	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	for curCall := range index.Calls(index.Object("errors", "As")) {
		call := curCall.Node().(*ast.CallExpr)
		if len(call.Args) < 2 {
			continue // spread call: errors.As(pair())
		}

		// Check for incorrect arguments.
		if err := checkAsTarget(info, call.Args[1]); err != nil {
			pass.ReportRangef(call, "%v", err)
			continue
		}
	}
	return nil, nil
}

// checkAsTarget reports an error if the second argument to errors.As is invalid.
func checkAsTarget(info *types.Info, e ast.Expr) error {
	t := info.Types[e].Type
	if types.Identical(t.Underlying(), anyType) {
		// A target of any is always allowed, since it often indicates
		// a value forwarded from another source.
		return nil
	}
	pt, ok := t.Underlying().(*types.Pointer)
	if !ok {
		return errors.New("second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type")
	}
	if types.Identical(pt.Elem(), errorType) {
		return errors.New("second argument to errors.As should not be *error")
	}
	if !types.IsInterface(pt.Elem()) && !types.AssignableTo(pt.Elem(), errorType) {
		return errors.New("second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type")
	}
	return nil
}

var (
	anyType   = types.Universe.Lookup("any").Type()
	errorType = types.Universe.Lookup("error").Type()
)


================================================
FILE: go/analysis/passes/errorsas/errorsas_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package errorsas_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/errorsas"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, errorsas.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/errorsas/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The errorsas command applies the golang.org/x/tools/go/analysis/passes/errorsas
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/errorsas"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(errorsas.Analyzer) }


================================================
FILE: go/analysis/passes/errorsas/testdata/src/a/a.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the errorsas checker.

package a

import "errors"

type myError int

func (myError) Error() string { return "" }

func perr() *error { return nil }

type iface interface {
	m()
}

func two() (error, interface{}) { return nil, nil }

func _() {
	var (
		e  error
		m  myError
		i  int
		f  iface
		ei interface{}
	)
	errors.As(nil, &e)     // want `second argument to errors.As should not be \*error`
	errors.As(nil, &m)     // *T where T implements error
	errors.As(nil, &f)     // *interface
	errors.As(nil, perr()) // want `second argument to errors.As should not be \*error`
	errors.As(nil, ei)     //  empty interface

	errors.As(nil, nil) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, e)   // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, m)   // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, f)   // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, &i)  // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(two())
}


================================================
FILE: go/analysis/passes/errorsas/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the errorsas checker.

package a

import "errors"

type myError[T any] struct{ t T }

func (myError[T]) Error() string { return "" }

type twice[T any] struct {
	t T
}

func perr[T any]() *T { return nil }

func two[T any]() (error, *T) { return nil, nil }

func _[E error](e E) {
	var (
		m  myError[int]
		tw twice[myError[int]]
	)
	errors.As(nil, &e)
	errors.As(nil, &m)            // *T where T implements error
	errors.As(nil, &tw.t)         // *T where T implements error
	errors.As(nil, perr[error]()) // want `second argument to errors.As should not be \*error`

	errors.As(nil, e)    // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, m)    // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(nil, tw.t) // want `second argument to errors.As must be a non-nil pointer to either a type that implements error, or to any interface type`
	errors.As(two[error]())
}


================================================
FILE: go/analysis/passes/fieldalignment/cmd/fieldalignment/main.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package main

import (
	"golang.org/x/tools/go/analysis/passes/fieldalignment"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(fieldalignment.Analyzer) }


================================================
FILE: go/analysis/passes/fieldalignment/fieldalignment.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fieldalignment defines an Analyzer that detects structs that would use less
// memory if their fields were sorted.
package fieldalignment

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"sort"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/astutil"
)

const Doc = `find structs that would use less memory if their fields were sorted

This analyzer finds structs that can be rearranged to use less memory, and provides
a suggested edit with the most compact order.

Note that there are two different diagnostics reported. One checks struct size,
and the other reports "pointer bytes" used. Pointer bytes is how many bytes of the
object that the garbage collector has to potentially scan for pointers, for example:

	struct { uint32; string }

have 16 pointer bytes because the garbage collector has to scan up through the string's
inner pointer.

	struct { string; *uint32 }

has 24 pointer bytes because it has to scan further through the *uint32.

	struct { string; uint32 }

has 8 because it can stop immediately after the string pointer.

Be aware that the most compact order is not always the most efficient.
In rare cases it may cause two variables each updated by its own goroutine
to occupy the same CPU cache line, inducing a form of memory contention
known as "false sharing" that slows down both goroutines.

Unlike most analyzers, which report likely mistakes, the diagnostics
produced by fieldanalyzer very rarely indicate a significant problem,
so the analyzer is not included in typical suites such as vet or
gopls. Use this standalone command to run it on your code:

   $ go install golang.org/x/tools/go/analysis/passes/fieldalignment/cmd/fieldalignment@latest
   $ fieldalignment [packages]

`

var Analyzer = &analysis.Analyzer{
	Name:     "fieldalignment",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/fieldalignment",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.StructType)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		var s *ast.StructType
		var ok bool
		if s, ok = node.(*ast.StructType); !ok {
			return
		}
		if tv, ok := pass.TypesInfo.Types[s]; ok {
			fieldalignment(pass, s, tv.Type.(*types.Struct))
		}
	})
	return nil, nil
}

var unsafePointerTyp = types.Unsafe.Scope().Lookup("Pointer").(*types.TypeName).Type()

func fieldalignment(pass *analysis.Pass, node *ast.StructType, typ *types.Struct) {
	wordSize := pass.TypesSizes.Sizeof(unsafePointerTyp)
	maxAlign := pass.TypesSizes.Alignof(unsafePointerTyp)

	s := gcSizes{wordSize, maxAlign}
	optimal, indexes := optimalOrder(typ, &s)
	optsz, optptrs := s.Sizeof(optimal), s.ptrdata(optimal)

	var message string
	if sz := s.Sizeof(typ); sz != optsz {
		message = fmt.Sprintf("struct of size %d could be %d", sz, optsz)
	} else if ptrs := s.ptrdata(typ); ptrs != optptrs {
		message = fmt.Sprintf("struct with %d pointer bytes could be %d", ptrs, optptrs)
	} else {
		// Already optimal order.
		return
	}

	// Analyzers borrow syntax tree; they do not own them and must modify them.
	// This Clone operation is a quick fix to the data race introduced
	// in CL 278872 by the clearing of the Comment and Doc fields below.
	node = astutil.CloneNode(node)

	// Flatten the ast node since it could have multiple field names per list item while
	// *types.Struct only have one item per field.
	// TODO: Preserve multi-named fields instead of flattening.
	var flat []*ast.Field
	for _, f := range node.Fields.List {
		// TODO: Preserve comment, for now get rid of them.
		//       See https://github.com/golang/go/issues/20744
		f.Comment = nil
		f.Doc = nil
		if len(f.Names) <= 1 {
			flat = append(flat, f)
			continue
		}
		for _, name := range f.Names {
			flat = append(flat, &ast.Field{
				Names: []*ast.Ident{name},
				Type:  f.Type,
			})
		}
	}

	// Sort fields according to the optimal order.
	var reordered []*ast.Field
	for _, index := range indexes {
		reordered = append(reordered, flat[index])
	}

	newStr := &ast.StructType{
		Fields: &ast.FieldList{
			List: reordered,
		},
	}

	// Write the newly aligned struct node to get the content for suggested fixes.
	var buf bytes.Buffer
	if err := format.Node(&buf, token.NewFileSet(), newStr); err != nil {
		return
	}

	pass.Report(analysis.Diagnostic{
		Pos:     node.Pos(),
		End:     node.Pos() + token.Pos(len("struct")),
		Message: message,
		SuggestedFixes: []analysis.SuggestedFix{{
			Message: "Rearrange fields",
			TextEdits: []analysis.TextEdit{{
				Pos:     node.Pos(),
				End:     node.End(),
				NewText: buf.Bytes(),
			}},
		}},
	})
}

func optimalOrder(str *types.Struct, sizes *gcSizes) (*types.Struct, []int) {
	nf := str.NumFields()

	type elem struct {
		index   int
		alignof int64
		sizeof  int64
		ptrdata int64
	}

	elems := make([]elem, nf)
	for i := range nf {
		field := str.Field(i)
		ft := field.Type()
		elems[i] = elem{
			i,
			sizes.Alignof(ft),
			sizes.Sizeof(ft),
			sizes.ptrdata(ft),
		}
	}

	sort.Slice(elems, func(i, j int) bool {
		ei := &elems[i]
		ej := &elems[j]

		// Place zero sized objects before non-zero sized objects.
		zeroi := ei.sizeof == 0
		zeroj := ej.sizeof == 0
		if zeroi != zeroj {
			return zeroi
		}

		// Next, place more tightly aligned objects before less tightly aligned objects.
		if ei.alignof != ej.alignof {
			return ei.alignof > ej.alignof
		}

		// Place pointerful objects before pointer-free objects.
		noptrsi := ei.ptrdata == 0
		noptrsj := ej.ptrdata == 0
		if noptrsi != noptrsj {
			return noptrsj
		}

		if !noptrsi {
			// If both have pointers...

			// ... then place objects with less trailing
			// non-pointer bytes earlier. That is, place
			// the field with the most trailing
			// non-pointer bytes at the end of the
			// pointerful section.
			traili := ei.sizeof - ei.ptrdata
			trailj := ej.sizeof - ej.ptrdata
			if traili != trailj {
				return traili < trailj
			}
		}

		// Lastly, order by size.
		if ei.sizeof != ej.sizeof {
			return ei.sizeof > ej.sizeof
		}

		return false
	})

	fields := make([]*types.Var, nf)
	indexes := make([]int, nf)
	for i, e := range elems {
		fields[i] = str.Field(e.index)
		indexes[i] = e.index
	}
	return types.NewStruct(fields, nil), indexes
}

// Code below based on go/types.StdSizes.

type gcSizes struct {
	WordSize int64
	MaxAlign int64
}

func (s *gcSizes) Alignof(T types.Type) int64 {
	// For arrays and structs, alignment is defined in terms
	// of alignment of the elements and fields, respectively.
	switch t := T.Underlying().(type) {
	case *types.Array:
		// spec: "For a variable x of array type: unsafe.Alignof(x)
		// is the same as unsafe.Alignof(x[0]), but at least 1."
		return s.Alignof(t.Elem())
	case *types.Struct:
		// spec: "For a variable x of struct type: unsafe.Alignof(x)
		// is the largest of the values unsafe.Alignof(x.f) for each
		// field f of x, but at least 1."
		max := int64(1)
		for i, nf := 0, t.NumFields(); i < nf; i++ {
			if a := s.Alignof(t.Field(i).Type()); a > max {
				max = a
			}
		}
		return max
	}
	a := s.Sizeof(T) // may be 0
	// spec: "For a variable x of any type: unsafe.Alignof(x) is at least 1."
	if a < 1 {
		return 1
	}
	if a > s.MaxAlign {
		return s.MaxAlign
	}
	return a
}

var basicSizes = [...]byte{
	types.Bool:       1,
	types.Int8:       1,
	types.Int16:      2,
	types.Int32:      4,
	types.Int64:      8,
	types.Uint8:      1,
	types.Uint16:     2,
	types.Uint32:     4,
	types.Uint64:     8,
	types.Float32:    4,
	types.Float64:    8,
	types.Complex64:  8,
	types.Complex128: 16,
}

func (s *gcSizes) Sizeof(T types.Type) int64 {
	switch t := T.Underlying().(type) {
	case *types.Basic:
		k := t.Kind()
		if int(k) < len(basicSizes) {
			if s := basicSizes[k]; s > 0 {
				return int64(s)
			}
		}
		if k == types.String {
			return s.WordSize * 2
		}
	case *types.Array:
		return t.Len() * s.Sizeof(t.Elem())
	case *types.Slice:
		return s.WordSize * 3
	case *types.Struct:
		nf := t.NumFields()
		if nf == 0 {
			return 0
		}

		var o int64
		max := int64(1)
		for i := range nf {
			ft := t.Field(i).Type()
			a, sz := s.Alignof(ft), s.Sizeof(ft)
			if a > max {
				max = a
			}
			if i == nf-1 && sz == 0 && o != 0 {
				sz = 1
			}
			o = align(o, a) + sz
		}
		return align(o, max)
	case *types.Interface:
		return s.WordSize * 2
	}
	return s.WordSize // catch-all
}

// align returns the smallest y >= x such that y % a == 0.
func align(x, a int64) int64 {
	y := x + a - 1
	return y - y%a
}

func (s *gcSizes) ptrdata(T types.Type) int64 {
	switch t := T.Underlying().(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.String, types.UnsafePointer:
			return s.WordSize
		}
		return 0
	case *types.Chan, *types.Map, *types.Pointer, *types.Signature, *types.Slice:
		return s.WordSize
	case *types.Interface:
		return 2 * s.WordSize
	case *types.Array:
		n := t.Len()
		if n == 0 {
			return 0
		}
		a := s.ptrdata(t.Elem())
		if a == 0 {
			return 0
		}
		z := s.Sizeof(t.Elem())
		return (n-1)*z + a
	case *types.Struct:
		nf := t.NumFields()
		if nf == 0 {
			return 0
		}

		var o, p int64
		for i := range nf {
			ft := t.Field(i).Type()
			a, sz := s.Alignof(ft), s.Sizeof(ft)
			fp := s.ptrdata(ft)
			o = align(o, a)
			if fp != 0 {
				p = o + fp
			}
			o += sz
		}
		return p
	}

	panic("impossible")
}


================================================
FILE: go/analysis/passes/fieldalignment/fieldalignment_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fieldalignment_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/fieldalignment"
)

func TestTest(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, fieldalignment.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a.go
================================================
package a

type Good struct {
	y int32
	x byte
	z byte
}

type Bad struct { // want "struct of size 12 could be 8"
	x byte
	y int32
	z byte
}

type ZeroGood struct {
	a [0]byte
	b uint32
}

type ZeroBad struct { // want "struct of size 8 could be 4"
	a uint32
	b [0]byte
}

type NoNameGood struct {
	Good
	y int32
	x byte
	z byte
}

type NoNameBad struct { // want "struct of size 20 could be 16"
	Good
	x byte
	y int32
	z byte
}

type WithComments struct { // want "struct of size 8 could be 4"
	// doc style comment
	a uint32  // field a comment
	b [0]byte // field b comment
	// other doc style comment

	// and a last comment
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a.go.golden
================================================
package a

type Good struct {
	y int32
	x byte
	z byte
}

type Bad struct {
	y int32
	x byte
	z byte
}

type ZeroGood struct {
	a [0]byte
	b uint32
}

type ZeroBad struct {
	b [0]byte
	a uint32
}

type NoNameGood struct {
	Good
	y int32
	x byte
	z byte
}

type NoNameBad struct {
	Good
	y int32
	x byte
	z byte
}

type WithComments struct {
	b [0]byte
	a uint32
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a_386.go
================================================
package a

type PointerGood struct {
	P   *int
	buf [1000]uintptr
}

type PointerBad struct { // want "struct with 4004 pointer bytes could be 4"
	buf [1000]uintptr
	P   *int
}

type PointerSorta struct {
	a struct {
		p *int
		q uintptr
	}
	b struct {
		p *int
		q [2]uintptr
	}
}

type PointerSortaBad struct { // want "struct with 16 pointer bytes could be 12"
	a struct {
		p *int
		q [2]uintptr
	}
	b struct {
		p *int
		q uintptr
	}
}

type MultiField struct { // want "struct of size 20 could be 12"
	b      bool
	i1, i2 int
	a3     [3]bool
	_      [0]func()
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a_386.go.golden
================================================
package a

type PointerGood struct {
	P   *int
	buf [1000]uintptr
}

type PointerBad struct {
	P   *int
	buf [1000]uintptr
}

type PointerSorta struct {
	a struct {
		p *int
		q uintptr
	}
	b struct {
		p *int
		q [2]uintptr
	}
}

type PointerSortaBad struct {
	b struct {
		p *int
		q uintptr
	}
	a struct {
		p *int
		q [2]uintptr
	}
}

type MultiField struct {
	_  [0]func()
	i1 int
	i2 int
	a3 [3]bool
	b  bool
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a_amd64.go
================================================
package a

type PointerGood struct {
	P   *int
	buf [1000]uintptr
}

type PointerBad struct { // want "struct with 8008 pointer bytes could be 8"
	buf [1000]uintptr
	P   *int
}

type PointerSorta struct {
	a struct {
		p *int
		q uintptr
	}
	b struct {
		p *int
		q [2]uintptr
	}
}

type PointerSortaBad struct { // want "struct with 32 pointer bytes could be 24"
	a struct {
		p *int
		q [2]uintptr
	}
	b struct {
		p *int
		q uintptr
	}
}

type MultiField struct { // want "struct of size 40 could be 24"
	b      bool
	i1, i2 int
	a3     [3]bool
	_      [0]func()
}

type Issue43233 struct { // want "struct with 88 pointer bytes could be 80"
	AllowedEvents []*string // allowed events
	BlockedEvents []*string // blocked events
	APIVersion    string    `mapstructure:"api_version"`
	BaseURL       string    `mapstructure:"base_url"`
	AccessToken   string    `mapstructure:"access_token"`
}


================================================
FILE: go/analysis/passes/fieldalignment/testdata/src/a/a_amd64.go.golden
================================================
package a

type PointerGood struct {
	P   *int
	buf [1000]uintptr
}

type PointerBad struct {
	P   *int
	buf [1000]uintptr
}

type PointerSorta struct {
	a struct {
		p *int
		q uintptr
	}
	b struct {
		p *int
		q [2]uintptr
	}
}

type PointerSortaBad struct {
	b struct {
		p *int
		q uintptr
	}
	a struct {
		p *int
		q [2]uintptr
	}
}

type MultiField struct {
	_  [0]func()
	i1 int
	i2 int
	a3 [3]bool
	b  bool
}

type Issue43233 struct {
	APIVersion    string `mapstructure:"api_version"`
	BaseURL       string `mapstructure:"base_url"`
	AccessToken   string `mapstructure:"access_token"`
	AllowedEvents []*string
	BlockedEvents []*string
}


================================================
FILE: go/analysis/passes/findcall/cmd/findcall/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The findcall command runs the findcall analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/findcall"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(findcall.Analyzer) }


================================================
FILE: go/analysis/passes/findcall/findcall.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package findcall defines an Analyzer that serves as a trivial
// example and test of the Analysis API. It reports a diagnostic for
// every call to a function or method of the name specified by its
// -name flag. It also exports a fact for each declaration that
// matches the name, plus a package-level fact if the package contained
// one or more such declarations.
package findcall

import (
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
)

const Doc = `find calls to a particular function

The findcall analysis reports calls to functions or methods
of a particular name.`

var Analyzer = &analysis.Analyzer{
	Name:             "findcall",
	Doc:              Doc,
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/findcall",
	Run:              run,
	RunDespiteErrors: true,
	FactTypes:        []analysis.Fact{new(foundFact)},
}

var name string // -name flag

func init() {
	Analyzer.Flags.StringVar(&name, "name", name, "name of the function to find")
}

func run(pass *analysis.Pass) (any, error) {
	for _, f := range pass.Files {
		ast.Inspect(f, func(n ast.Node) bool {
			if call, ok := n.(*ast.CallExpr); ok {
				var id *ast.Ident
				switch fun := call.Fun.(type) {
				case *ast.Ident:
					id = fun
				case *ast.SelectorExpr:
					id = fun.Sel
				}
				if id != nil && !pass.TypesInfo.Types[id].IsType() && id.Name == name {
					pass.Report(analysis.Diagnostic{
						Pos:     call.Lparen,
						Message: fmt.Sprintf("call of %s(...)", id.Name),
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: fmt.Sprintf("Add '_TEST_'"),
							TextEdits: []analysis.TextEdit{{
								Pos:     call.Lparen,
								End:     call.Lparen,
								NewText: []byte("_TEST_"),
							}},
						}},
					})
				}
			}
			return true
		})
	}

	// Export a fact for each matching function.
	//
	// These facts are produced only to test the testing
	// infrastructure in the analysistest package.
	// They are not consumed by the findcall Analyzer
	// itself, as would happen in a more realistic example.
	for _, f := range pass.Files {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok && decl.Name.Name == name {
				if obj, ok := pass.TypesInfo.Defs[decl.Name].(*types.Func); ok {
					pass.ExportObjectFact(obj, new(foundFact))
				}
			}
		}
	}

	if len(pass.AllObjectFacts()) > 0 {
		pass.ExportPackageFact(new(foundFact))
	}

	return nil, nil
}

// foundFact is a fact associated with functions that match -name.
// We use it to exercise the fact machinery in tests.
type foundFact struct{}

func (*foundFact) String() string { return "found" }
func (*foundFact) AFact()         {}


================================================
FILE: go/analysis/passes/findcall/findcall_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package findcall_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/findcall"
)

func init() {
	findcall.Analyzer.Flags.Set("name", "println")
}

// TestFromStringLiterals demonstrates how to test an analysis using
// a table of string literals for each test case.
//
// Such tests are typically quite compact.
func TestFromStringLiterals(t *testing.T) {

	for _, test := range [...]struct {
		desc    string
		pkgpath string
		files   map[string]string
	}{
		{
			desc:    "SimpleTest",
			pkgpath: "main",
			files: map[string]string{"main/main.go": `package main // want package:"found"

func main() {
	println("hello") // want "call of println"
	print("goodbye") // not a call of println
}

func println(s string) {} // want println:"found"`,
			},
		},
	} {
		t.Run(test.desc, func(t *testing.T) {
			dir, cleanup, err := analysistest.WriteFiles(test.files)
			if err != nil {
				t.Fatal(err)
			}
			defer cleanup()
			analysistest.Run(t, dir, findcall.Analyzer, test.pkgpath)
		})
	}
}

// TestFromFileSystem demonstrates how to test an analysis using input
// files stored in the file system.
//
// These tests have the advantages that test data can be edited
// directly, and that files named in error messages can be opened.
// However, they tend to spread a small number of lines of text across a
// rather deep directory hierarchy, and obscure similarities among
// related tests, especially when tests involve multiple packages, or
// multiple variants of a single scenario.
func TestFromFileSystem(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, findcall.Analyzer, "a") // loads testdata/src/a/a.go.
}


================================================
FILE: go/analysis/passes/findcall/testdata/src/a/a.go
================================================
package main // want package:"found"

func main() {
	println("hi") // want "call of println"
	print("hi")   // not a call of println
}

func println(s string) {} // want println:"found"


================================================
FILE: go/analysis/passes/findcall/testdata/src/a/a.go.golden
================================================
package main // want package:"found"

func main() {
	println_TEST_("hi") // want "call of println"
	print("hi")         // not a call of println
}

func println(s string) {} // want println:"found"


================================================
FILE: go/analysis/passes/framepointer/framepointer.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package framepointer defines an Analyzer that reports assembly code
// that clobbers the frame pointer before saving it.
package framepointer

import (
	"go/build"
	"regexp"
	"strings"
	"unicode"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

const Doc = "report assembly that clobbers the frame pointer before saving it"

var Analyzer = &analysis.Analyzer{
	Name: "framepointer",
	Doc:  Doc,
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/framepointer",
	Run:  run,
}

// Per-architecture checks for instructions.
// Assume comments, leading and trailing spaces are removed.
type arch struct {
	isFPWrite             func(string) bool
	isFPRead              func(string) bool
	isUnconditionalBranch func(string) bool
}

var re = regexp.MustCompile

func hasAnyPrefix(s string, prefixes ...string) bool {
	for _, p := range prefixes {
		if strings.HasPrefix(s, p) {
			return true
		}
	}
	return false
}

var arches = map[string]arch{
	"amd64": {
		isFPWrite: re(`,\s*BP$`).MatchString, // TODO: can have false positive, e.g. for TESTQ BP,BP. Seems unlikely.
		isFPRead:  re(`\bBP\b`).MatchString,
		isUnconditionalBranch: func(s string) bool {
			return hasAnyPrefix(s, "JMP", "RET")
		},
	},
	"arm64": {
		isFPWrite: func(s string) bool {
			if i := strings.LastIndex(s, ","); i > 0 && strings.HasSuffix(s[i:], "R29") {
				return true
			}
			if hasAnyPrefix(s, "LDP", "LDAXP", "LDXP", "CASP") {
				// Instructions which write to a pair of registers, e.g.
				//	LDP 8(R0), (R26, R29)
				//	CASPD (R2, R3), (R2), (R26, R29)
				lp := strings.LastIndex(s, "(")
				rp := strings.LastIndex(s, ")")
				if lp > -1 && lp < rp {
					return strings.Contains(s[lp:rp], ",") && strings.Contains(s[lp:rp], "R29")
				}
			}
			return false
		},
		isFPRead: re(`\bR29\b`).MatchString,
		isUnconditionalBranch: func(s string) bool {
			// Get just the instruction
			if i := strings.IndexFunc(s, unicode.IsSpace); i > 0 {
				s = s[:i]
			}
			return s == "B" || s == "JMP" || s == "RET"
		},
	},
}

func run(pass *analysis.Pass) (any, error) {
	arch, ok := arches[build.Default.GOARCH]
	if !ok {
		return nil, nil
	}
	if build.Default.GOOS != "linux" && build.Default.GOOS != "darwin" {
		return nil, nil
	}

	// Find assembly files to work on.
	var sfiles []string
	for _, fname := range pass.OtherFiles {
		if strings.HasSuffix(fname, ".s") && pass.Pkg.Path() != "runtime" {
			sfiles = append(sfiles, fname)
		}
	}

	for _, fname := range sfiles {
		content, tf, err := analyzerutil.ReadFile(pass, fname)
		if err != nil {
			return nil, err
		}

		lines := strings.SplitAfter(string(content), "\n")
		active := false
		for lineno, line := range lines {
			lineno++

			// Ignore comments and commented-out code.
			if i := strings.Index(line, "//"); i >= 0 {
				line = line[:i]
			}
			line = strings.TrimSpace(line)
			if line == "" {
				continue
			}

			// We start checking code at a TEXT line for a frameless function.
			if strings.HasPrefix(line, "TEXT") && strings.Contains(line, "(SB)") && strings.Contains(line, "$0") {
				active = true
				continue
			}
			if !active {
				continue
			}

			if arch.isFPWrite(line) {
				pass.Reportf(tf.LineStart(lineno), "frame pointer is clobbered before saving")
				active = false
				continue
			}
			if arch.isFPRead(line) || arch.isUnconditionalBranch(line) {
				active = false
				continue
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/framepointer/framepointer_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package framepointer_test

import (
	"go/build"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/framepointer"
)

func Test(t *testing.T) {
	if build.Default.GOOS != "linux" && build.Default.GOOS != "darwin" {
		// The test has an os-generic assembly file, testdata/a/asm_amd64.s.
		// It should produce errors on linux or darwin, but not on other archs.
		// Unfortunately, there's no way to say that in the "want" comments
		// in that file. So we skip testing on other GOOSes. The framepointer
		// analyzer should not report any errors on those GOOSes, so it's not
		// really a hard test on those platforms.
		t.Skipf("test for GOOS=%s is not implemented", build.Default.GOOS)
	}
	analysistest.Run(t, analysistest.TestData(), framepointer.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm_amd64.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT ·bad1(SB), 0, $0
	MOVQ	$0, BP // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad2(SB), 0, $0
	MOVQ	AX, BP // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad3(SB), 0, $0
	MOVQ	6(AX), BP // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad4(SB), 0, $0
	CMPQ	AX, BX
	JEQ	skip
	// Assume the above conditional branch is not taken
	MOVQ	$0, BP // want `frame pointer is clobbered before saving`
skip:
	RET
TEXT ·good1(SB), 0, $0
	PUSHQ	BP
	MOVQ	$0, BP // this is ok
	POPQ	BP
	RET
TEXT ·good2(SB), 0, $0
	MOVQ	BP, BX
	MOVQ	$0, BP // this is ok
	MOVQ	BX, BP
	RET
TEXT ·good3(SB), 0, $0
	CMPQ	AX, BX
	JMP	skip
	MOVQ	$0, BP // this is ok
skip:
	RET
TEXT ·good4(SB), 0, $0
	RET
	MOVQ	$0, BP // this is ok
	RET
TEXT ·good5(SB), 0, $8
	MOVQ	$0, BP // this is ok
	RET


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm_arm64.s
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT ·bad1(SB), 0, $0
	MOVD	$0, R29 // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad2(SB), 0, $0
	MOVD	R1, R29 // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad3(SB), 0, $0
	MOVD	6(R2), R29 // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad4(SB), 0, $0
	LDP	0(R1), (R26, R29) // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad5(SB), 0, $0
	AND	$0x1, R3, R29 // want `frame pointer is clobbered before saving`
	RET
TEXT ·bad6(SB), 0, $0
	CMP	R1, R2
	BEQ	skip
	// Assume that the above conditional branch is not taken
	MOVD	$0, R29 // want `frame pointer is clobbered before saving`
skip:
	RET
TEXT ·bad7(SB), 0, $0
	BL	·good4(SB)
	AND	$0x1, R3, R29 // want `frame pointer is clobbered before saving`
	RET
TEXT ·good1(SB), 0, $0
	STPW 	(R29, R30), -32(RSP)
	MOVD	$0, R29 // this is ok
	LDPW	32(RSP), (R29, R30)
	RET
TEXT ·good2(SB), 0, $0
	MOVD	R29, R1
	MOVD	$0, R29 // this is ok
	MOVD	R1, R29
	RET
TEXT ·good3(SB), 0, $0
	CMP	R1, R2
	B	skip
	MOVD	$0, R29 // this is ok
skip:
	RET
TEXT ·good4(SB), 0, $0
	RET
	MOVD	$0, R29 // this is ok
	RET
TEXT ·good5(SB), 0, $8
	MOVD	$0, R29 // this is ok
	RET


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm_darwin_amd64.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT ·z1(SB), 0, $0
	MOVQ	$0, BP // want `frame pointer is clobbered before saving`
	RET


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm_linux_amd64.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT ·z1(SB), 0, $0
	MOVQ	$0, BP // want `frame pointer is clobbered before saving`
	RET


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/asm_windows_amd64.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

TEXT ·z1(SB), 0, $0
	MOVQ	$0, BP // not an error on windows
	RET


================================================
FILE: go/analysis/passes/framepointer/testdata/src/a/buildtag_amd64.s
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build nope

TEXT ·bt1(SB), 0, $0
	MOVQ	$0, BP // ok because of build tag
	RET


================================================
FILE: go/analysis/passes/gofix/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package gofix defines an Analyzer that checks "//go:fix inline" directives.
See golang.org/x/tools/go/analysis/passes/inline/doc.go for details.

# Analyzer gofixdirective

gofixdirective: validate uses of gofix comment directives

The gofixdirective analyzer checks "//go:fix inline" directives for correctness.

The proposal https://go.dev/issue/32816 introduces the "//go:fix" directives.

The analyzer checks for the following issues:

- A constant definition can be marked for inlining only if it refers to another
named constant.

	//go:fix inline
	const (
		a = 1       // error
		b = iota    // error
		c = a       // OK
		d = math.Pi // OK
	)

- A type definition can be marked for inlining only if it is an alias.

	//go:fix inline
	type (
		T int    // error
		A = int  // OK
	)

- An alias whose right-hand side contains a non-literal array size
cannot be marked for inlining.

	const two = 2

	//go:fix inline
	type (
		A = []int     // OK
		B = [1]int    // OK
		C = [two]int  // error
	)
*/
package gofix


================================================
FILE: go/analysis/passes/gofix/gofix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gofix defines an analyzer that checks go:fix directives.
package gofix

import (
	_ "embed"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/analysis/passes/internal/gofixdirective"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "gofixdirective",
	Doc:      analyzerutil.MustExtractDoc(doc, "gofixdirective"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/gofix",
	Run:      run,
	Requires: []*analysis.Analyzer{inspect.Analyzer},
}

func run(pass *analysis.Pass) (any, error) {
	root := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector).Root()
	gofixdirective.Find(pass, root, nil)
	return nil, nil
}


================================================
FILE: go/analysis/passes/gofix/gofix_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gofix_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/gofix"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, gofix.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/gofix/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the gofix checker.

package a

const one = 1

//go:fix inline
const (
	in3  = one
	in4  = one
	bad1 = 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`
)

//go:fix inline
const in5,
	in6,
	bad2 = one, one,
	one + 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

//go:fix inline
const (
	a = iota // want `invalid //go:fix inline directive: const value is iota`
	b
	in7 = one
)

func shadow() {
	//go:fix inline
	const a = iota // want `invalid //go:fix inline directive: const value is iota`

	const iota = 2

	//go:fix inline
	const b = iota // not an error: iota is not the builtin
}

// Type aliases

//go:fix inline
type A int // want `invalid //go:fix inline directive: not a type alias`

//go:fix inline
type E = map[[one]string][]int // want `invalid //go:fix inline directive: array types not supported`


================================================
FILE: go/analysis/passes/hostport/hostport.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package hostport defines an analyzer for calls to net.Dial with
// addresses of the form "%s:%d" or "%s:%s", which work only with IPv4.
package hostport

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"strconv"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/types/typeutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

const Doc = `check format of addresses passed to net.Dial

This analyzer flags code that produce network address strings using
fmt.Sprintf, as in this example:

    addr := fmt.Sprintf("%s:%d", host, 12345) // "will not work with IPv6"
    ...
    conn, err := net.Dial("tcp", addr)       // "when passed to dial here"

The analyzer suggests a fix to use the correct approach, a call to
net.JoinHostPort:

    addr := net.JoinHostPort(host, "12345")
    ...
    conn, err := net.Dial("tcp", addr)

A similar diagnostic and fix are produced for a format string of "%s:%s".
`

var Analyzer = &analysis.Analyzer{
	Name:     "hostport",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/hostport",
	Requires: []*analysis.Analyzer{inspect.Analyzer, typeindexanalyzer.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	var (
		index      = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info       = pass.TypesInfo
		fmtSprintf = index.Object("fmt", "Sprintf")
	)
	if !index.Used(fmtSprintf) {
		return nil, nil // fast path: package doesn't use fmt.Sprintf
	}

	// checkAddr reports a diagnostic (and returns true) if e
	// is a call of the form fmt.Sprintf("%s:%d", ...).
	// The diagnostic includes a fix.
	//
	// dialCall is non-nil if the Dial call is non-local
	// but within the same file.
	checkAddr := func(e ast.Expr, dialCall *ast.CallExpr) {
		if call, ok := e.(*ast.CallExpr); ok &&
			len(call.Args) == 3 &&
			typeutil.Callee(info, call) == fmtSprintf {

			// Examine format string.
			formatArg := call.Args[0]
			if tv := info.Types[formatArg]; tv.Value != nil {
				numericPort := false
				format := constant.StringVal(tv.Value)
				switch format {
				case "%s:%d":
					// Have: fmt.Sprintf("%s:%d", host, port)
					numericPort = true

				case "%s:%s":
					// Have: fmt.Sprintf("%s:%s", host, portStr)
					// Keep port string as is.

				default:
					return
				}

				// Use granular edits to preserve original formatting.
				edits := []analysis.TextEdit{
					{
						// Replace fmt.Sprintf with net.JoinHostPort.
						Pos:     call.Fun.Pos(),
						End:     call.Fun.End(),
						NewText: []byte("net.JoinHostPort"),
					},
					{
						// Delete format string.
						Pos: formatArg.Pos(),
						End: call.Args[1].Pos(),
					},
				}

				// Turn numeric port into a string.
				if numericPort {
					port := call.Args[2]

					// Is port an integer literal?
					//
					// (Don't allow arbitrary constants k otherwise the
					// transformation k => fmt.Sprintf("%d", "123")
					// loses the symbolic connection to k.)
					var kPort int64 = -1
					if lit, ok := port.(*ast.BasicLit); ok && lit.Kind == token.INT {
						if v, err := strconv.ParseInt(lit.Value, 0, 64); err == nil {
							kPort = v
						}
					}
					if kPort >= 0 {
						// literal: 0x7B  => "123"
						edits = append(edits, analysis.TextEdit{
							Pos:     port.Pos(),
							End:     port.End(),
							NewText: fmt.Appendf(nil, `"%d"`, kPort), // (decimal)
						})
					} else {
						// non-literal: port => fmt.Sprintf("%d", port)
						edits = append(edits, []analysis.TextEdit{
							{
								Pos:     port.Pos(),
								End:     port.Pos(),
								NewText: []byte(`fmt.Sprintf("%d", `),
							},
							{
								Pos:     port.End(),
								End:     port.End(),
								NewText: []byte(`)`),
							},
						}...)
					}
				}

				// Refer to Dial call, if not adjacent.
				suffix := ""
				if dialCall != nil {
					suffix = fmt.Sprintf(" (passed to net.Dial at L%d)",
						pass.Fset.Position(dialCall.Pos()).Line)
				}

				pass.Report(analysis.Diagnostic{
					// Highlight the format string.
					Pos:     formatArg.Pos(),
					End:     formatArg.End(),
					Message: fmt.Sprintf("address format %q does not work with IPv6%s", format, suffix),
					SuggestedFixes: []analysis.SuggestedFix{{
						Message:   "Replace fmt.Sprintf with net.JoinHostPort",
						TextEdits: edits,
					}},
				})
			}
		}
	}

	// Check address argument of each call to net.Dial et al.
	for _, callee := range []types.Object{
		index.Object("net", "Dial"),
		index.Object("net", "DialTimeout"),
		index.Selection("net", "Dialer", "Dial"),
	} {
		for curCall := range index.Calls(callee) {
			call := curCall.Node().(*ast.CallExpr)
			switch address := call.Args[1].(type) {
			case *ast.CallExpr:
				if len(call.Args) == 2 { // avoid spread-call edge case
					// net.Dial("tcp", fmt.Sprintf("%s:%d", ...))
					checkAddr(address, nil)
				}

			case *ast.Ident:
				// addr := fmt.Sprintf("%s:%d", ...)
				// ...
				// net.Dial("tcp", addr)

				// Search for decl of addrVar within common ancestor of addrVar and Dial call.
				// TODO(adonovan): abstract "find RHS of statement that assigns var v".
				// TODO(adonovan): reject if there are other assignments to var v.
				if addrVar, ok := info.Uses[address].(*types.Var); ok {
					if curId, ok := index.Def(addrVar); ok {
						// curIdent is the declaring ast.Ident of addr.
						switch parent := curId.Parent().Node().(type) {
						case *ast.AssignStmt:
							if len(parent.Rhs) == 1 {
								// Have: addr := fmt.Sprintf("%s:%d", ...)
								checkAddr(parent.Rhs[0], call)
							}

						case *ast.ValueSpec:
							if len(parent.Values) == 1 {
								// Have: var addr = fmt.Sprintf("%s:%d", ...)
								checkAddr(parent.Values[0], call)
							}
						}
					}
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/hostport/hostport_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package hostport_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/hostport"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, hostport.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/hostport/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/hostport"
)

func main() { singlechecker.Main(hostport.Analyzer) }


================================================
FILE: go/analysis/passes/hostport/testdata/src/a/a.go
================================================
package a

import (
	"fmt"
	"net"
)

func direct(host string, port int, portStr string) {
	// Dial, directly called with result of Sprintf.
	net.Dial("tcp", fmt.Sprintf("%s:%d", host, port)) // want `address format "%s:%d" does not work with IPv6`

	net.Dial("tcp", fmt.Sprintf("%s:%s", host, portStr)) // want `address format "%s:%s" does not work with IPv6`
}

// port is a literal:
var addr4 = fmt.Sprintf("%s:%d", "localhost", 123) // want `address format "%s:%d" does not work with IPv6 \(passed to net.Dial at L39\)`

func indirect(host string, port int) {
	// Dial, addr is immediately preceding.
	{
		addr1 := fmt.Sprintf("%s:%d", host, port) // want `address format "%s:%d" does not work with IPv6.*at L22`
		net.Dial("tcp", addr1)
	}

	// DialTimeout, addr is in ancestor block.
	addr2 := fmt.Sprintf("%s:%d", host, port) // want `address format "%s:%d" does not work with IPv6.*at L28`
	{
		net.DialTimeout("tcp", addr2, 0)
	}

	// Dialer.Dial, addr is declared with var.
	var dialer net.Dialer
	{
		var addr3 = fmt.Sprintf("%s:%d", host, port) // want `address format "%s:%d" does not work with IPv6.*at L35`
		dialer.Dial("tcp", addr3)
	}

	// Dialer.Dial again, addr is declared at package level.
	dialer.Dial("tcp", addr4)
}

// Regression tests for crashes in well-typed code that nonetheless mis-uses Sprintf:
// too few arguments, or port is not an integer.
var (
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d"))
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d", "host"))
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d", "host", "port")) // want `address format "%s:%d" does not work with IPv6`
)

func _() {
	// port is a non-constant literal
	const port = 0x7B
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d", "localhost", port)) // want `address format "%s:%d" does not work with IPv6`
}


================================================
FILE: go/analysis/passes/hostport/testdata/src/a/a.go.golden
================================================
package a

import (
	"fmt"
	"net"
)

func direct(host string, port int, portStr string) {
	// Dial, directly called with result of Sprintf.
	net.Dial("tcp", net.JoinHostPort(host, fmt.Sprintf("%d", port))) // want `address format "%s:%d" does not work with IPv6`

	net.Dial("tcp", net.JoinHostPort(host, portStr)) // want `address format "%s:%s" does not work with IPv6`
}

// port is a literal:
var addr4 = net.JoinHostPort("localhost", "123") // want `address format "%s:%d" does not work with IPv6 \(passed to net.Dial at L39\)`

func indirect(host string, port int) {
	// Dial, addr is immediately preceding.
	{
		addr1 := net.JoinHostPort(host, fmt.Sprintf("%d", port)) // want `address format "%s:%d" does not work with IPv6.*at L22`
		net.Dial("tcp", addr1)
	}

	// DialTimeout, addr is in ancestor block.
	addr2 := net.JoinHostPort(host, fmt.Sprintf("%d", port)) // want `address format "%s:%d" does not work with IPv6.*at L28`
	{
		net.DialTimeout("tcp", addr2, 0)
	}

	// Dialer.Dial, addr is declared with var.
	var dialer net.Dialer
	{
		var addr3 = net.JoinHostPort(host, fmt.Sprintf("%d", port)) // want `address format "%s:%d" does not work with IPv6.*at L35`
		dialer.Dial("tcp", addr3)
	}

	// Dialer.Dial again, addr is declared at package level.
	dialer.Dial("tcp", addr4)
}

// Regression tests for crashes in well-typed code that nonetheless mis-uses Sprintf:
// too few arguments, or port is not an integer.
var (
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d"))
	_, _ = net.Dial("tcp", fmt.Sprintf("%s:%d", "host"))
	_, _ = net.Dial("tcp", net.JoinHostPort("host", fmt.Sprintf("%d", "port"))) // want `address format "%s:%d" does not work with IPv6`
)

func _() {
	// port is a non-constant literal
	const port = 0x7B
	_, _ = net.Dial("tcp", net.JoinHostPort("localhost", fmt.Sprintf("%d", port))) // want `address format "%s:%d" does not work with IPv6`
}


================================================
FILE: go/analysis/passes/httpmux/cmd/httpmux/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The httpmux command runs the httpmux analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/httpmux"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(httpmux.Analyzer) }


================================================
FILE: go/analysis/passes/httpmux/httpmux.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package httpmux

import (
	"go/ast"
	"go/constant"
	"go/types"
	"regexp"
	"slices"
	"strings"

	"golang.org/x/mod/semver"
	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = `report using Go 1.22 enhanced ServeMux patterns in older Go versions

The httpmux analysis is active for Go modules configured to run with Go 1.21 or
earlier versions. It reports calls to net/http.ServeMux.Handle and HandleFunc
methods whose patterns use features added in Go 1.22, like HTTP methods (such as
"GET") and wildcards. (See https://pkg.go.dev/net/http#ServeMux for details.)
Such patterns can be registered in older versions of Go, but will not behave as expected.`

var Analyzer = &analysis.Analyzer{
	Name:     "httpmux",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/httpmux",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

var inTest bool // So Go version checks can be skipped during testing.

func run(pass *analysis.Pass) (any, error) {
	if !inTest {
		// Check that Go version is 1.21 or earlier.
		if goVersionAfter121(goVersion(pass.Pkg)) {
			return nil, nil
		}
	}
	if !typesinternal.Imports(pass.Pkg, "net/http") {
		return nil, nil
	}
	// Look for calls to ServeMux.Handle or ServeMux.HandleFunc.
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}

	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		if isServeMuxRegisterCall(pass, call) {
			pat, ok := stringConstantExpr(pass, call.Args[0])
			if ok && likelyEnhancedPattern(pat) {
				pass.ReportRangef(call.Args[0], "possible enhanced ServeMux pattern used with Go version before 1.22 (update go.mod file?)")
			}
		}
	})
	return nil, nil
}

// isServeMuxRegisterCall reports whether call is a static call to one of:
// - net/http.Handle
// - net/http.HandleFunc
// - net/http.ServeMux.Handle
// - net/http.ServeMux.HandleFunc
// TODO(jba): consider expanding this to accommodate wrappers around these functions.
func isServeMuxRegisterCall(pass *analysis.Pass, call *ast.CallExpr) bool {
	fn := typeutil.StaticCallee(pass.TypesInfo, call)
	if fn == nil {
		return false
	}
	if typesinternal.IsFunctionNamed(fn, "net/http", "Handle", "HandleFunc") {
		return true
	}
	if !isMethodNamed(fn, "net/http", "Handle", "HandleFunc") {
		return false
	}
	recv := fn.Signature().Recv() // isMethodNamed() -> non-nil
	isPtr, named := typesinternal.ReceiverNamed(recv)
	return isPtr && typesinternal.IsTypeNamed(named, "net/http", "ServeMux")
}

// isMethodNamed reports when a function f is a method,
// in a package with the path pkgPath and the name of f is in names.
//
// (Unlike [analysis.IsMethodNamed], it ignores the receiver type name.)
func isMethodNamed(f *types.Func, pkgPath string, names ...string) bool {
	if f == nil {
		return false
	}
	if f.Pkg() == nil || f.Pkg().Path() != pkgPath {
		return false // not at pkgPath
	}
	if f.Signature().Recv() == nil {
		return false // not a method
	}
	return slices.Contains(names, f.Name())
}

// stringConstantExpr returns expression's string constant value.
//
// ("", false) is returned if expression isn't a string
// constant.
func stringConstantExpr(pass *analysis.Pass, expr ast.Expr) (string, bool) {
	lit := pass.TypesInfo.Types[expr].Value
	if lit != nil && lit.Kind() == constant.String {
		return constant.StringVal(lit), true
	}
	return "", false
}

// A valid wildcard must start a segment, and its name must be valid Go
// identifier.
var wildcardRegexp = regexp.MustCompile(`/\{[_\pL][_\pL\p{Nd}]*(\.\.\.)?\}`)

// likelyEnhancedPattern reports whether the ServeMux pattern pat probably
// contains either an HTTP method name or a wildcard, extensions added in Go 1.22.
func likelyEnhancedPattern(pat string) bool {
	if strings.Contains(pat, " ") {
		// A space in the pattern suggests that it begins with an HTTP method.
		return true
	}
	return wildcardRegexp.MatchString(pat)
}

func goVersionAfter121(goVersion string) bool {
	if goVersion == "" { // Maybe the stdlib?
		return true
	}
	version := versionFromGoVersion(goVersion)
	return semver.Compare(version, "v1.21") > 0
}

func goVersion(pkg *types.Package) string {
	// types.Package.GoVersion did not exist before Go 1.21.
	if p, ok := any(pkg).(interface{ GoVersion() string }); ok {
		return p.GoVersion()
	}
	return ""
}

var (
	// Regexp for matching go tags. The groups are:
	// 1  the major.minor version
	// 2  the patch version, or empty if none
	// 3  the entire prerelease, if present
	// 4  the prerelease type ("beta" or "rc")
	// 5  the prerelease number
	tagRegexp = regexp.MustCompile(`^go(\d+\.\d+)(\.\d+|)((beta|rc)(\d+))?$`)
)

// Copied from pkgsite/internal/stdlib.VersionForTag.
func versionFromGoVersion(goVersion string) string {
	// Special cases for go1.
	if goVersion == "go1" {
		return "v1.0.0"
	}
	if goVersion == "go1.0" {
		return ""
	}
	m := tagRegexp.FindStringSubmatch(goVersion)
	if m == nil {
		return ""
	}
	version := "v" + m[1]
	if m[2] != "" {
		version += m[2]
	} else {
		version += ".0"
	}
	if m[3] != "" {
		version += "-" + m[4] + "." + m[5]
	}
	return version
}


================================================
FILE: go/analysis/passes/httpmux/httpmux_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package httpmux

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	tests := []string{"a"}
	inTest = true
	analysistest.Run(t, testdata, Analyzer, tests...)
}

func TestGoVersion(t *testing.T) {
	for _, test := range []struct {
		in   string
		want bool
	}{
		{"", true},
		{"go1", false},
		{"go1.21", false},
		{"go1.21rc3", false},
		{"go1.22", true},
		{"go1.22rc1", true},
	} {
		got := goVersionAfter121(test.in)
		if got != test.want {
			t.Errorf("%q: got %t, want %t", test.in, got, test.want)
		}
	}
}


================================================
FILE: go/analysis/passes/httpmux/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the httpmux checker.

package a

import "net/http"

func _() {
	http.HandleFunc("GET /x", nil)  // want "enhanced ServeMux pattern"
	http.HandleFunc("/{a}/b/", nil) // want "enhanced ServeMux pattern"
	mux := http.NewServeMux()
	mux.Handle("example.com/c/{d}", nil) // want "enhanced ServeMux pattern"
	mux.HandleFunc("/{x...}", nil)       // want "enhanced ServeMux pattern"

	// Should not match.

	// not an enhanced pattern
	http.Handle("/", nil)

	// invalid wildcard; will panic in 1.22
	http.HandleFunc("/{/a/}", nil)
	mux.Handle("/{1}", nil)
	mux.Handle("/x{a}", nil)

	// right package, wrong method
	http.ParseTime("GET /")

	// right function name, wrong package
	Handle("GET /", nil)
	HandleFunc("GET /", nil)

	// right method name, wrong type
	var sm ServeMux
	sm.Handle("example.com/c/{d}", nil)
	sm.HandleFunc("method /{x...}", nil)
}

func Handle(pat string, x any)     {}
func HandleFunc(pat string, x any) {}

type ServeMux struct{}

func (*ServeMux) Handle(pat string, x any)     {}
func (*ServeMux) HandleFunc(pat string, x any) {}


================================================
FILE: go/analysis/passes/httpresponse/httpresponse.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package httpresponse defines an Analyzer that checks for mistakes
// using HTTP responses.
package httpresponse

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = `check for mistakes using HTTP responses

A common mistake when using the net/http package is to defer a function
call to close the http.Response Body before checking the error that
determines whether the response is valid:

	resp, err := http.Head(url)
	defer resp.Body.Close()
	if err != nil {
		log.Fatal(err)
	}
	// (defer statement belongs here)

This checker helps uncover latent nil dereference bugs by reporting a
diagnostic for such mistakes.`

var Analyzer = &analysis.Analyzer{
	Name:     "httpresponse",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/httpresponse",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// Fast path: if the package doesn't import net/http,
	// skip the traversal.
	if !typesinternal.Imports(pass.Pkg, "net/http") {
		return nil, nil
	}

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.WithStack(nodeFilter, func(n ast.Node, push bool, stack []ast.Node) bool {
		if !push {
			return true
		}
		call := n.(*ast.CallExpr)
		if !isHTTPFuncOrMethodOnClient(pass.TypesInfo, call) {
			return true // the function call is not related to this check.
		}

		// Find the innermost containing block, and get the list
		// of statements starting with the one containing call.
		stmts, ncalls := restOfBlock(stack)
		if len(stmts) < 2 {
			// The call to the http function is the last statement of the block.
			return true
		}

		// Skip cases in which the call is wrapped by another (#52661).
		// Example:  resp, err := checkError(http.Get(url))
		if ncalls > 1 {
			return true
		}

		asg, ok := stmts[0].(*ast.AssignStmt)
		if !ok {
			return true // the first statement is not assignment.
		}

		resp := rootIdent(asg.Lhs[0])
		if resp == nil {
			return true // could not find the http.Response in the assignment.
		}

		def, ok := stmts[1].(*ast.DeferStmt)
		if !ok {
			return true // the following statement is not a defer.
		}
		root := rootIdent(def.Call.Fun)
		if root == nil {
			return true // could not find the receiver of the defer call.
		}

		if resp.Obj == root.Obj {
			pass.ReportRangef(root, "using %s before checking for errors", resp.Name)
		}
		return true
	})
	return nil, nil
}

// isHTTPFuncOrMethodOnClient checks whether the given call expression is on
// either a function of the net/http package or a method of http.Client that
// returns (*http.Response, error).
func isHTTPFuncOrMethodOnClient(info *types.Info, expr *ast.CallExpr) bool {
	fun, _ := expr.Fun.(*ast.SelectorExpr)
	sig, _ := info.Types[fun].Type.(*types.Signature)
	if sig == nil {
		return false // the call is not of the form x.f()
	}

	res := sig.Results()
	if res.Len() != 2 {
		return false // the function called does not return two values.
	}
	isPtr, named := typesinternal.ReceiverNamed(res.At(0))
	if !isPtr || named == nil || !typesinternal.IsTypeNamed(named, "net/http", "Response") {
		return false // the first return type is not *http.Response.
	}

	errorType := types.Universe.Lookup("error").Type()
	if !types.Identical(res.At(1).Type(), errorType) {
		return false // the second return type is not error
	}

	typ := info.Types[fun.X].Type
	if typ == nil {
		id, ok := fun.X.(*ast.Ident)
		return ok && id.Name == "http" // function in net/http package.
	}

	if typesinternal.IsTypeNamed(typ, "net/http", "Client") {
		return true // method on http.Client.
	}
	ptr, ok := types.Unalias(typ).(*types.Pointer)
	return ok && typesinternal.IsTypeNamed(ptr.Elem(), "net/http", "Client") // method on *http.Client.
}

// restOfBlock, given a traversal stack, finds the innermost containing
// block and returns the suffix of its statements starting with the current
// node, along with the number of call expressions encountered.
func restOfBlock(stack []ast.Node) ([]ast.Stmt, int) {
	var ncalls int
	for i := len(stack) - 1; i >= 0; i-- {
		if b, ok := stack[i].(*ast.BlockStmt); ok {
			for j, v := range b.List {
				if v == stack[i+1] {
					return b.List[j:], ncalls
				}
			}
			break
		}

		if _, ok := stack[i].(*ast.CallExpr); ok {
			ncalls++
		}
	}
	return nil, 0
}

// rootIdent finds the root identifier x in a chain of selections x.y.z, or nil if not found.
func rootIdent(n ast.Node) *ast.Ident {
	switch n := n.(type) {
	case *ast.SelectorExpr:
		return rootIdent(n.X)
	case *ast.Ident:
		return n
	default:
		return nil
	}
}


================================================
FILE: go/analysis/passes/httpresponse/httpresponse_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package httpresponse_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/httpresponse"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, httpresponse.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/httpresponse/testdata/src/a/a.go
================================================
package a

import (
	"log"
	"net/http"
)

func goodHTTPGet() {
	res, err := http.Get("http://foo.com")
	if err != nil {
		log.Fatal(err)
	}
	defer res.Body.Close()
}

func badHTTPGet() {
	res, err := http.Get("http://foo.com")
	defer res.Body.Close() // want "using res before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func badHTTPHead() {
	res, err := http.Head("http://foo.com")
	defer res.Body.Close() // want "using res before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func goodClientGet() {
	client := http.DefaultClient
	res, err := client.Get("http://foo.com")
	if err != nil {
		log.Fatal(err)
	}
	defer res.Body.Close()
}

func badClientPtrGet() {
	client := http.DefaultClient
	resp, err := client.Get("http://foo.com")
	defer resp.Body.Close() // want "using resp before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func badClientGet() {
	client := http.Client{}
	resp, err := client.Get("http://foo.com")
	defer resp.Body.Close() // want "using resp before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func badClientPtrDo() {
	client := http.DefaultClient
	req, err := http.NewRequest("GET", "http://foo.com", nil)
	if err != nil {
		log.Fatal(err)
	}

	resp, err := client.Do(req)
	defer resp.Body.Close() // want "using resp before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func badClientDo() {
	var client http.Client
	req, err := http.NewRequest("GET", "http://foo.com", nil)
	if err != nil {
		log.Fatal(err)
	}

	resp, err := client.Do(req)
	defer resp.Body.Close() // want "using resp before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func goodUnwrapResp() {
	unwrapResp := func(resp *http.Response, err error) *http.Response {
		if err != nil {
			panic(err)
		}
		return resp
	}
	resp := unwrapResp(http.Get("https://golang.org"))
	// It is ok to call defer here immediately as err has
	// been checked in unwrapResp (see #52661).
	defer resp.Body.Close()
}

func badUnwrapResp() {
	unwrapResp := func(resp *http.Response, err error) string {
		if err != nil {
			panic(err)
		}
		return "https://golang.org/" + resp.Status
	}
	resp, err := http.Get(unwrapResp(http.Get("https://golang.org")))
	defer resp.Body.Close() // want "using resp before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

type i66259 struct{}

func (_ *i66259) Foo() (*int, int) { return nil, 1 }

func issue66259() {
	var f *i66259
	f.Foo()
}


================================================
FILE: go/analysis/passes/httpresponse/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the httpresponse checker.

package typeparams

import (
	"log"
	"net/http"
)

func badHTTPGet[T any](url string) {
	res, err := http.Get(url)
	defer res.Body.Close() // want "using res before checking for errors"
	if err != nil {
		log.Fatal(err)
	}
}

func mkClient[T any]() *T {
	return nil
}

func badClientHTTPGet() {
	client := mkClient[http.Client]()
	res, _ := client.Get("")
	defer res.Body.Close() // want "using res before checking for errors"
}

// User-defined type embedded "http.Client"
type S[P any] struct {
	http.Client
}

func unmatchedClientTypeName(client S[string]) {
	res, _ := client.Get("")
	defer res.Body.Close() // the name of client's type doesn't match "*http.Client"
}

// User-defined Client type
type C[P any] interface {
	Get(url string) (resp *P, err error)
}

func userDefinedClientType(client C[http.Response]) {
	resp, _ := client.Get("http://foo.com")
	defer resp.Body.Close() // "client" is not of type "*http.Client"
}


================================================
FILE: go/analysis/passes/ifaceassert/cmd/ifaceassert/main.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The ifaceassert command runs the ifaceassert analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/ifaceassert"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(ifaceassert.Analyzer) }


================================================
FILE: go/analysis/passes/ifaceassert/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package ifaceassert defines an Analyzer that flags
// impossible interface-interface type assertions.
//
// # Analyzer ifaceassert
//
// ifaceassert: detect impossible interface-to-interface type assertions
//
// This checker flags type assertions v.(T) and corresponding type-switch cases
// in which the static type V of v is an interface that cannot possibly implement
// the target interface T. This occurs when V and T contain methods with the same
// name but different signatures. Example:
//
//	var v interface {
//		Read()
//	}
//	_ = v.(io.Reader)
//
// The Read method in v has a different signature than the Read method in
// io.Reader, so this assertion cannot succeed.
package ifaceassert


================================================
FILE: go/analysis/passes/ifaceassert/ifaceassert.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ifaceassert

import (
	_ "embed"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typeparams"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "ifaceassert",
	Doc:      analyzerutil.MustExtractDoc(doc, "ifaceassert"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/ifaceassert",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

// assertableTo checks whether interface v can be asserted into t. It returns
// nil on success, or the first conflicting method on failure.
func assertableTo(free *typeparams.Free, v, t types.Type) *types.Func {
	if t == nil || v == nil {
		// not assertable to, but there is no missing method
		return nil
	}
	// ensure that v and t are interfaces
	V, _ := v.Underlying().(*types.Interface)
	T, _ := t.Underlying().(*types.Interface)
	if V == nil || T == nil {
		return nil
	}

	// Mitigations for interface comparisons and generics.
	// TODO(https://github.com/golang/go/issues/50658): Support more precise conclusion.
	if free.Has(V) || free.Has(T) {
		return nil
	}
	if f, wrongType := types.MissingMethod(V, T, false); wrongType {
		return f
	}
	return nil
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.TypeAssertExpr)(nil),
		(*ast.TypeSwitchStmt)(nil),
	}
	var free typeparams.Free
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		var (
			assert  *ast.TypeAssertExpr // v.(T) expression
			targets []ast.Expr          // interfaces T in v.(T)
		)
		switch n := n.(type) {
		case *ast.TypeAssertExpr:
			// take care of v.(type) in *ast.TypeSwitchStmt
			if n.Type == nil {
				return
			}
			assert = n
			targets = append(targets, n.Type)
		case *ast.TypeSwitchStmt:
			// retrieve type assertion from type switch's 'assign' field
			switch t := n.Assign.(type) {
			case *ast.ExprStmt:
				assert = t.X.(*ast.TypeAssertExpr)
			case *ast.AssignStmt:
				assert = t.Rhs[0].(*ast.TypeAssertExpr)
			}
			// gather target types from case clauses
			for _, c := range n.Body.List {
				targets = append(targets, c.(*ast.CaseClause).List...)
			}
		}
		V := pass.TypesInfo.TypeOf(assert.X)
		for _, target := range targets {
			T := pass.TypesInfo.TypeOf(target)
			if f := assertableTo(&free, V, T); f != nil {
				pass.Reportf(
					target.Pos(),
					"impossible type assertion: no type can implement both %v and %v (conflicting types for %v method)",
					V, T, f.Name(),
				)
			}
		}
	})
	return nil, nil
}


================================================
FILE: go/analysis/passes/ifaceassert/ifaceassert_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ifaceassert_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/ifaceassert"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, ifaceassert.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/ifaceassert/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the ifaceassert checker.

package a

import "io"

func InterfaceAssertionTest() {
	var (
		a io.ReadWriteSeeker
		b interface {
			Read()
			Write()
		}
	)
	_ = a.(io.Reader)
	_ = a.(io.ReadWriter)
	_ = b.(io.Reader)  // want `^impossible type assertion: no type can implement both interface{Read\(\); Write\(\)} and io.Reader \(conflicting types for Read method\)$`
	_ = b.(interface { // want `^impossible type assertion: no type can implement both interface{Read\(\); Write\(\)} and interface{Read\(p \[\]byte\) \(n int, err error\)} \(conflicting types for Read method\)$`
		Read(p []byte) (n int, err error)
	})

	switch a.(type) {
	case io.ReadWriter:
	case interface { // want `^impossible type assertion: no type can implement both io.ReadWriteSeeker and interface{Write\(\)} \(conflicting types for Write method\)$`
		Write()
	}:
	default:
	}

	switch b := b.(type) {
	case io.ReadWriter, interface{ Read() }: // want `^impossible type assertion: no type can implement both interface{Read\(\); Write\(\)} and io.ReadWriter \(conflicting types for Read method\)$`
	case io.Writer: // want `^impossible type assertion: no type can implement both interface{Read\(\); Write\(\)} and io.Writer \(conflicting types for Write method\)$`
	default:
		_ = b
	}
}


================================================
FILE: go/analysis/passes/ifaceassert/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "io"

type SourceReader[Source any] interface {
	Read(p Source) (n int, err error)
}

func GenericInterfaceAssertionTest[T io.Reader]() {
	var (
		a SourceReader[[]byte]
		b SourceReader[[]int]
		r io.Reader
	)
	_ = a.(io.Reader)
	_ = b.(io.Reader) // want `^impossible type assertion: no type can implement both typeparams.SourceReader\[\[\]int\] and io.Reader \(conflicting types for Read method\)$`

	_ = r.(SourceReader[[]byte])
	_ = r.(SourceReader[[]int]) // want `^impossible type assertion: no type can implement both io.Reader and typeparams.SourceReader\[\[\]int\] \(conflicting types for Read method\)$`
	_ = r.(T)                   // not actually an iface assertion, so checked by the type checker.

	switch a.(type) {
	case io.Reader:
	default:
	}

	switch b.(type) {
	case io.Reader: // want `^impossible type assertion: no type can implement both typeparams.SourceReader\[\[\]int\] and io.Reader \(conflicting types for Read method\)$`

	default:
	}
}

// Issue 50658: Check for type parameters in type switches.
type Float interface {
	float32 | float64
}

type Doer[F Float] interface {
	Do() F
}

func Underlying[F Float](v Doer[F]) string {
	switch v.(type) {
	case Doer[float32]:
		return "float32!"
	case Doer[float64]:
		return "float64!"
	default:
		return "<unknown>"
	}
}

func DoIf[F Float]() {
	// This is a synthetic function to create a non-generic to generic assignment.
	// This function does not make much sense.
	var v Doer[float32]
	if t, ok := v.(Doer[F]); ok {
		t.Do()
	}
}

func IsASwitch[F Float, U Float](v Doer[F]) bool {
	switch v.(type) {
	case Doer[U]:
		return true
	}
	return false
}

func IsA[F Float, U Float](v Doer[F]) bool {
	_, is := v.(Doer[U])
	return is
}

func LayeredTypes[F Float]() {
	// This is a synthetic function cover more isParameterized cases.
	type T interface {
		foo() struct{ _ map[T][2]chan *F }
	}
	type V interface {
		foo() struct{ _ map[T][2]chan *float32 }
	}
	var t T
	var v V
	t, _ = v.(T)
	_ = t
}

type X[T any] struct{}

func (x X[T]) m(T) {}

func InstancesOfGenericMethods() {
	var x interface{ m(string) }
	// _ = x.(X[int])    // BAD. Not enabled as it does not type check.
	_ = x.(X[string]) // OK
}


================================================
FILE: go/analysis/passes/inline/cmd/inline/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The inline command applies the inliner to the specified packages of
// Go source code. Run this command to report all fixes:
//
//	$ go run ./go/analysis/passes/inline/cmd/inline packages...
//
// Run this command to preview the changes:
//
//	$ go run ./go/analysis/passes/inline/cmd/inline -fix -diff packages...
//
// And run this command to apply them:
//
//	$ go run ./go/analysis/passes/inline/cmd/inline -fix packages...
//
// This internal command is not officially supported. In the long
// term, we plan to migrate this functionality into "go fix"; see Go
// issues https//go.dev/issue/32816, 71859, 73605.
package main

import (
	"golang.org/x/tools/go/analysis/passes/inline"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(inline.Analyzer) }


================================================
FILE: go/analysis/passes/inline/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package inline defines an analyzer that inlines calls to functions
and uses of constants marked with a "//go:fix inline" directive.

# Analyzer inline

inline: apply fixes based on 'go:fix inline' comment directives

The inline analyzer inlines functions and constants that are marked for inlining.

## Functions

Given a function that is marked for inlining, like this one:

	//go:fix inline
	func Square(x int) int { return Pow(x, 2) }

this analyzer will recommend that calls to the function elsewhere, in the same
or other packages, should be inlined.

Inlining can be used to move off of a deprecated function:

	// Deprecated: prefer Pow(x, 2).
	//go:fix inline
	func Square(x int) int { return Pow(x, 2) }

It can also be used to move off of an obsolete package,
as when the import path has changed or a higher major version is available:

	package pkg

	import pkg2 "pkg/v2"

	//go:fix inline
	func F() { pkg2.F(nil) }

Replacing a call pkg.F() by pkg2.F(nil) can have no effect on the program,
so this mechanism provides a low-risk way to update large numbers of calls.
We recommend, where possible, expressing the old API in terms of the new one
to enable automatic migration.

The inliner takes care to avoid behavior changes, even subtle ones,
such as changes to the order in which argument expressions are
evaluated. When it cannot safely eliminate all parameter variables,
it may introduce a "binding declaration" of the form

	var params = args

to evaluate argument expressions in the correct order and bind them to
parameter variables. Since the resulting code transformation may be
stylistically suboptimal, such inlinings may be disabled by specifying
the -inline.allow_binding_decl=false flag to the analyzer driver.

(In cases where it is not safe to "reduce" a call—that is, to replace
a call f(x) by the body of function f, suitably substituted—the
inliner machinery is capable of replacing f by a function literal,
func(){...}(). However, the inline analyzer discards all such
"literalizations" unconditionally, again on grounds of style.)

## Constants

Given a constant that is marked for inlining, like this one:

	//go:fix inline
	const Ptr = Pointer

this analyzer will recommend that uses of Ptr should be replaced with Pointer.

As with functions, inlining can be used to replace deprecated constants and
constants in obsolete packages.

A constant definition can be marked for inlining only if it refers to another
named constant.

The "//go:fix inline" comment must appear before a single const declaration on its own,
as above; before a const declaration that is part of a group, as in this case:

	const (
	   C = 1
	   //go:fix inline
	   Ptr = Pointer
	)

or before a group, applying to every constant in the group:

	//go:fix inline
	const (
		Ptr = Pointer
	    Val = Value
	)

The proposal https://go.dev/issue/32816 introduces the "//go:fix inline" directives.

You can use this command to apply inline fixes en masse:

	$ go run golang.org/x/tools/go/analysis/passes/inline/cmd/inline@latest -fix ./...

# Analyzer gofixdirective

gofixdirective: validate uses of //go:fix comment directives

The gofixdirective analyzer checks "//go:fix inline" directives for correctness.
See the documentation for the gofix analyzer for more about "/go:fix inline".
*/
package inline


================================================
FILE: go/analysis/passes/inline/inline.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

import (
	"fmt"
	"go/ast"
	"go/types"
	"slices"
	"strings"

	_ "embed"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/analysis/passes/internal/gofixdirective"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/refactor/inline"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name: "inline",
	Doc:  analyzerutil.MustExtractDoc(doc, "inline"),
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/inline",
	Run:  run,
	FactTypes: []analysis.Fact{
		(*goFixInlineFuncFact)(nil),
		(*goFixInlineConstFact)(nil),
		(*goFixInlineAliasFact)(nil),
	},
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
}

var (
	allowBindingDecl bool
	lazyEdits        bool
)

func init() {
	Analyzer.Flags.BoolVar(&allowBindingDecl, "allow_binding_decl", false,
		"permit inlinings that require a 'var params = args' declaration")
	Analyzer.Flags.BoolVar(&lazyEdits, "lazy_edits", false,
		"compute edits lazily (only meaningful to gopls driver)")
}

// analyzer holds the state for this analysis.
type analyzer struct {
	pass  *analysis.Pass
	root  inspector.Cursor
	index *typeindex.Index
	// memoization of repeated calls for same file.
	fileContent map[string][]byte
	// memoization of fact imports (nil => no fact)
	inlinableFuncs   map[*types.Func]*inline.Callee
	inlinableConsts  map[*types.Const]*goFixInlineConstFact
	inlinableAliases map[*types.TypeName]*goFixInlineAliasFact
}

func run(pass *analysis.Pass) (any, error) {
	a := &analyzer{
		pass:             pass,
		root:             pass.ResultOf[inspect.Analyzer].(*inspector.Inspector).Root(),
		index:            pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index),
		fileContent:      make(map[string][]byte),
		inlinableFuncs:   make(map[*types.Func]*inline.Callee),
		inlinableConsts:  make(map[*types.Const]*goFixInlineConstFact),
		inlinableAliases: make(map[*types.TypeName]*goFixInlineAliasFact),
	}
	gofixdirective.Find(pass, a.root, a)
	a.inline()
	return nil, nil
}

// HandleFunc exports a fact for functions marked with go:fix.
func (a *analyzer) HandleFunc(decl *ast.FuncDecl) {
	content, err := a.readFile(decl)
	if err != nil {
		a.pass.Reportf(decl.Doc.Pos(), "invalid inlining candidate: cannot read source file: %v", err)
		return
	}
	callee, err := inline.AnalyzeCallee(discard, a.pass.Fset, a.pass.Pkg, a.pass.TypesInfo, decl, content)
	if err != nil {
		a.pass.Reportf(decl.Doc.Pos(), "invalid inlining candidate: %v", err)
		return
	}
	fn := a.pass.TypesInfo.Defs[decl.Name].(*types.Func)
	a.pass.ExportObjectFact(fn, &goFixInlineFuncFact{callee})
	a.inlinableFuncs[fn] = callee
}

// HandleAlias exports a fact for aliases marked with go:fix.
func (a *analyzer) HandleAlias(spec *ast.TypeSpec) {
	// Remember that this is an inlinable alias.
	typ := &goFixInlineAliasFact{}
	lhs := a.pass.TypesInfo.Defs[spec.Name].(*types.TypeName)
	a.inlinableAliases[lhs] = typ
	// Create a fact only if the LHS is exported and defined at top level.
	// We create a fact even if the RHS is non-exported,
	// so we can warn about uses in other packages.
	if lhs.Exported() && typesinternal.IsPackageLevel(lhs) {
		a.pass.ExportObjectFact(lhs, typ)
	}
}

// HandleConst exports a fact for constants marked with go:fix.
func (a *analyzer) HandleConst(nameIdent, rhsIdent *ast.Ident) {
	lhs := a.pass.TypesInfo.Defs[nameIdent].(*types.Const)
	rhs := a.pass.TypesInfo.Uses[rhsIdent].(*types.Const) // must be so in a well-typed program
	con := &goFixInlineConstFact{
		RHSName:    rhs.Name(),
		RHSPkgName: rhs.Pkg().Name(),
		RHSPkgPath: rhs.Pkg().Path(),
	}
	if rhs.Pkg() == a.pass.Pkg {
		con.rhsObj = rhs
	}
	a.inlinableConsts[lhs] = con
	// Create a fact only if the LHS is exported and defined at top level.
	// We create a fact even if the RHS is non-exported,
	// so we can warn about uses in other packages.
	if lhs.Exported() && typesinternal.IsPackageLevel(lhs) {
		a.pass.ExportObjectFact(lhs, con)
	}
}

// inline inlines each static call to an inlinable function
// and each reference to an inlinable constant or type alias.
func (a *analyzer) inline() {
	for cur := range a.root.Preorder((*ast.CallExpr)(nil), (*ast.Ident)(nil)) {
		switch n := cur.Node().(type) {
		case *ast.CallExpr:
			a.inlineCall(n, cur)

		case *ast.Ident:
			switch t := a.pass.TypesInfo.Uses[n].(type) {
			case *types.TypeName:
				a.inlineAlias(t, cur)
			case *types.Const:
				a.inlineConst(t, cur)
			}
		}
	}
}

// If call is a call to an inlinable func, suggest inlining its use at cur.
func (a *analyzer) inlineCall(call *ast.CallExpr, cur inspector.Cursor) {
	if fn := typeutil.StaticCallee(a.pass.TypesInfo, call); fn != nil {
		// Inlinable?
		callee, ok := a.inlinableFuncs[fn]
		if !ok {
			var fact goFixInlineFuncFact
			if a.pass.ImportObjectFact(fn, &fact) {
				callee = fact.Callee
				a.inlinableFuncs[fn] = callee
			}
		}
		if callee == nil {
			return // nope
		}

		if a.withinTestOf(cur, fn) {
			return // don't inline a function from within its own test
		}

		// Compute the edits.
		//
		// Ordinarily the analyzer reports a fix containing
		// edits. However, the algorithm is somewhat expensive
		// (unnecessarily so: see go.dev/issue/75773) so
		// to reduce costs in gopls, we omit the edits,
		// meaning that gopls must compute them on demand
		// (based on the Diagnostic.Category) when they are
		// requested via a code action.
		//
		// This does mean that the following categories of
		// caller-dependent obstacles to inlining will be
		// reported when the gopls user requests the fix,
		// rather than by quietly suppressing the diagnostic:
		// - shadowing problems
		// - callee imports inaccessible "internal" packages
		// - callee refers to nonexported symbols
		// - callee uses too-new Go features
		// - inlining call from a cgo file
		var edits []analysis.TextEdit
		if !lazyEdits {
			// Inline the call.
			caller := &inline.Caller{
				Fset:  a.pass.Fset,
				Types: a.pass.Pkg,
				Info:  a.pass.TypesInfo,
				File:  astutil.EnclosingFile(cur),
				Call:  call,
				CountUses: func(pkgname *types.PkgName) int {
					return moreiters.Len(a.index.Uses(pkgname))
				},
			}
			res, err := inline.Inline(caller, callee, &inline.Options{Logf: discard})
			if err != nil {
				a.pass.Reportf(call.Lparen, "%v", err)
				return
			}

			if res.Literalized {
				// Users are not fond of inlinings that literalize
				// f(x) to func() { ... }(), so avoid them.
				//
				// (Unfortunately the inliner is very timid,
				// and often literalizes when it cannot prove that
				// reducing the call is safe; the user of this tool
				// has no indication of what the problem is.)
				return
			}
			if res.BindingDecl && !allowBindingDecl {
				// When applying fix en masse, users are similarly
				// unenthusiastic about inlinings that cannot
				// entirely eliminate the parameters and
				// insert a 'var params = args' declaration.
				// The flag allows them to decline such fixes.
				return
			}
			edits = res.Edits
		}

		a.pass.Report(analysis.Diagnostic{
			Pos:      call.Pos(),
			End:      call.End(),
			Message:  fmt.Sprintf("Call of %v should be inlined", callee),
			Category: "inline_call", // keep consistent with gopls/internal/golang.fixInlineCall
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   fmt.Sprintf("Inline call of %v", callee),
				TextEdits: edits, // within gopls, this is nil => compute fix's edits lazily
			}},
		})
	}
}

// withinTestOf reports whether cur is within a dedicated test
// function for the inlinable target function.
// A call within its dedicated test should not be inlined.
func (a *analyzer) withinTestOf(cur inspector.Cursor, target *types.Func) bool {
	curFuncDecl, ok := moreiters.First(cur.Enclosing((*ast.FuncDecl)(nil)))
	if !ok {
		return false // not in a function
	}
	funcDecl := curFuncDecl.Node().(*ast.FuncDecl)
	if funcDecl.Recv != nil {
		return false // not a test func
	}
	if strings.TrimSuffix(a.pass.Pkg.Path(), "_test") != target.Pkg().Path() {
		return false // different package
	}
	if !strings.HasSuffix(a.pass.Fset.File(funcDecl.Pos()).Name(), "_test.go") {
		return false // not a test file
	}

	// Computed expected SYMBOL portion of "TestSYMBOL_comment"
	// for the target symbol.
	symbol := target.Name()
	if recv := target.Signature().Recv(); recv != nil {
		_, named := typesinternal.ReceiverNamed(recv)
		symbol = named.Obj().Name() + "_" + symbol
	}

	// TODO(adonovan): use a proper Test function parser.
	fname := funcDecl.Name.Name
	for _, pre := range []string{"Test", "Example", "Bench"} {
		if fname == pre+symbol || strings.HasPrefix(fname, pre+symbol+"_") {
			return true
		}
	}

	return false
}

// If tn is the TypeName of an inlinable alias, suggest inlining its use at cur.
func (a *analyzer) inlineAlias(tn *types.TypeName, curId inspector.Cursor) {
	inalias, ok := a.inlinableAliases[tn]
	if !ok {
		var fact goFixInlineAliasFact
		if a.pass.ImportObjectFact(tn, &fact) {
			inalias = &fact
			a.inlinableAliases[tn] = inalias
		}
	}
	if inalias == nil {
		return // nope
	}

	alias := tn.Type().(*types.Alias)
	// Remember the names of the alias's type params. When we check for shadowing
	// later, we'll ignore these because they won't appear in the replacement text.
	typeParamNames := map[*types.TypeName]bool{}
	for tp := range alias.TypeParams().TypeParams() {
		typeParamNames[tp.Obj()] = true
	}
	rhs := alias.Rhs()
	curPath := a.pass.Pkg.Path()
	curFile := astutil.EnclosingFile(curId)
	id := curId.Node().(*ast.Ident)

	// Find the complete identifier, which may take any of these forms:
	//       Id
	//       Id[T]
	//       Id[K, V]
	//   pkg.Id
	//   pkg.Id[T]
	//   pkg.Id[K, V]
	var expr ast.Expr = id
	if curId.ParentEdgeKind() == edge.SelectorExpr_Sel {
		curId = curId.Parent()
		expr = curId.Node().(ast.Expr)
	}
	// If expr is part of an IndexExpr or IndexListExpr, we'll need that node.
	// Given C[int], TypeOf(C) is generic but TypeOf(C[int]) is instantiated.
	switch curId.ParentEdgeKind() {
	case edge.IndexExpr_X:
		expr = curId.Parent().Node().(*ast.IndexExpr)
	case edge.IndexListExpr_X:
		expr = curId.Parent().Node().(*ast.IndexListExpr)
	}
	t := a.pass.TypesInfo.TypeOf(expr).(*types.Alias) // type of entire identifier
	if targs := t.TypeArgs(); targs.Len() > 0 {
		// Instantiate the alias with the type args from this use.
		// For example, given type A = M[K, V], compute the type of the use
		// A[int, Foo] as M[int, Foo].
		// Don't validate instantiation: it can't panic unless we have a bug,
		// in which case seeing the stack trace via telemetry would be helpful.
		instAlias, _ := types.Instantiate(nil, alias, slices.Collect(targs.Types()), false)
		rhs = instAlias.(*types.Alias).Rhs()
	}

	// We have an identifier A here (n), possibly qualified by a package
	// identifier (sel.n), and an inlinable "type A = rhs" elsewhere.
	//
	// We can replace A with rhs if no name in rhs is shadowed at n's position,
	// and every package in rhs is importable by the current package.
	var (
		importPrefixes = map[string]string{curPath: ""} // from pkg path to prefix
		edits          []analysis.TextEdit
	)
	for _, tn := range typenames(rhs) {
		// Ignore the type parameters of the alias: they won't appear in the result.
		if typeParamNames[tn] {
			continue
		}
		var pkgPath, pkgName string
		if pkg := tn.Pkg(); pkg != nil {
			pkgPath = pkg.Path()
			pkgName = pkg.Name()
		}
		if pkgPath == "" || pkgPath == curPath {
			// The name is in the current package or the universe scope, so no import
			// is required. Check that it is not shadowed (that is, that the type
			// it refers to in rhs is the same one it refers to at n).
			scope := a.pass.TypesInfo.Scopes[curFile].Innermost(id.Pos()) // n's scope
			_, obj := scope.LookupParent(tn.Name(), id.Pos())             // what qn.name means in n's scope
			if obj != tn {
				return
			}
		} else if !packagepath.CanImport(a.pass.Pkg.Path(), pkgPath) {
			// If this package can't see the package of this part of rhs, we can't inline.
			return
		} else if _, ok := importPrefixes[pkgPath]; !ok {
			// Use AddImport to add pkgPath if it's not there already. Associate the prefix it assigns
			// with the prefix it assigns
			// with the package path for use by the TypeString qualifier below.
			prefix, eds := refactor.AddImport(
				a.pass.TypesInfo, curFile, pkgName, pkgPath, tn.Name(), id.Pos())
			importPrefixes[pkgPath] = strings.TrimSuffix(prefix, ".")
			edits = append(edits, eds...)
		}
	}

	// To get the replacement text, render the alias RHS using the package prefixes
	// we assigned above.
	newText := types.TypeString(rhs, func(p *types.Package) string {
		if p == a.pass.Pkg {
			return ""
		}
		if prefix, ok := importPrefixes[p.Path()]; ok {
			return prefix
		}
		panic(fmt.Sprintf("in %q, package path %q has no import prefix", rhs, p.Path()))
	})
	a.reportInline("type alias", "Type alias", expr, edits, newText)
}

// typenames returns the TypeNames for types within t (including t itself) that have
// them: basic types, named types and alias types.
// The same name may appear more than once.
func typenames(t types.Type) []*types.TypeName {
	var tns []*types.TypeName

	var visit func(types.Type)
	visit = func(t types.Type) {
		if hasName, ok := t.(interface{ Obj() *types.TypeName }); ok {
			tns = append(tns, hasName.Obj())
		}
		switch t := t.(type) {
		case *types.Basic:
			tns = append(tns, types.Universe.Lookup(t.Name()).(*types.TypeName))
		case *types.Named:
			for t := range t.TypeArgs().Types() {
				visit(t)
			}
		case *types.Alias:
			for t := range t.TypeArgs().Types() {
				visit(t)
			}
		case *types.TypeParam:
			tns = append(tns, t.Obj())
		case *types.Pointer:
			visit(t.Elem())
		case *types.Slice:
			visit(t.Elem())
		case *types.Array:
			visit(t.Elem())
		case *types.Chan:
			visit(t.Elem())
		case *types.Map:
			visit(t.Key())
			visit(t.Elem())
		case *types.Struct:
			for field := range t.Fields() {
				visit(field.Type())
			}
		case *types.Signature:
			// Ignore the receiver: although it may be present, it has no meaning
			// in a type expression.
			// Ditto for receiver type params.
			// Also, function type params cannot appear in a type expression.
			if t.TypeParams() != nil {
				panic("Signature.TypeParams in type expression")
			}
			visit(t.Params())
			visit(t.Results())
		case *types.Interface:
			for etyp := range t.EmbeddedTypes() {
				visit(etyp)
			}
			for method := range t.ExplicitMethods() {
				visit(method.Type())
			}
		case *types.Tuple:
			for v := range t.Variables() {
				visit(v.Type())
			}
		case *types.Union:
			panic("Union in type expression")
		default:
			panic(fmt.Sprintf("unknown type %T", t))
		}
	}

	visit(t)

	return tns
}

// If con is an inlinable constant, suggest inlining its use at cur.
func (a *analyzer) inlineConst(con *types.Const, cur inspector.Cursor) {
	incon, ok := a.inlinableConsts[con]
	if !ok {
		var fact goFixInlineConstFact
		if a.pass.ImportObjectFact(con, &fact) {
			incon = &fact
			a.inlinableConsts[con] = incon
		}
	}
	if incon == nil {
		return // nope
	}

	// If n is qualified by a package identifier, we'll need the full selector expression.
	curFile := astutil.EnclosingFile(cur)
	n := cur.Node().(*ast.Ident)

	// We have an identifier A here (n), possibly qualified by a package identifier (sel.X,
	// where sel is the parent of n), // and an inlinable "const A = B" elsewhere (incon).
	// Consider replacing A with B.

	// Check that the expression we are inlining (B) means the same thing
	// (refers to the same object) in n's scope as it does in A's scope.
	// If the RHS is not in the current package, AddImport will handle
	// shadowing, so we only need to worry about when both expressions
	// are in the current package.
	if a.pass.Pkg.Path() == incon.RHSPkgPath {
		// incon.rhsObj is the object referred to by B in the definition of A.
		scope := a.pass.TypesInfo.Scopes[curFile].Innermost(n.Pos()) // n's scope
		_, obj := scope.LookupParent(incon.RHSName, n.Pos())         // what "B" means in n's scope
		if obj == nil {
			// Should be impossible: if code at n can refer to the LHS,
			// it can refer to the RHS.
			panic(fmt.Sprintf("no object for inlinable const %s RHS %s", n.Name, incon.RHSName))
		}
		if obj != incon.rhsObj {
			// "B" means something different here than at the inlinable const's scope.
			return
		}
	} else if !packagepath.CanImport(a.pass.Pkg.Path(), incon.RHSPkgPath) {
		// If this package can't see the RHS's package, we can't inline.
		return
	}
	var (
		importPrefix string
		edits        []analysis.TextEdit
	)
	if incon.RHSPkgPath != a.pass.Pkg.Path() {
		importPrefix, edits = refactor.AddImport(
			a.pass.TypesInfo, curFile, incon.RHSPkgName, incon.RHSPkgPath, incon.RHSName, n.Pos())
	}
	// If n is qualified by a package identifier, we'll need the full selector expression.
	var expr ast.Expr = n
	if cur.ParentEdgeKind() == edge.SelectorExpr_Sel {
		expr = cur.Parent().Node().(ast.Expr)
	}
	a.reportInline("constant", "Constant", expr, edits, importPrefix+incon.RHSName)
}

// reportInline reports a diagnostic for fixing an inlinable name.
func (a *analyzer) reportInline(kind, capKind string, ident ast.Expr, edits []analysis.TextEdit, newText string) {
	edits = append(edits, analysis.TextEdit{
		Pos:     ident.Pos(),
		End:     ident.End(),
		NewText: []byte(newText),
	})
	name := astutil.Format(a.pass.Fset, ident)
	a.pass.Report(analysis.Diagnostic{
		Pos:     ident.Pos(),
		End:     ident.End(),
		Message: fmt.Sprintf("%s %s should be inlined", capKind, name),
		SuggestedFixes: []analysis.SuggestedFix{{
			Message:   fmt.Sprintf("Inline %s %s", kind, name),
			TextEdits: edits,
		}},
	})
}

func (a *analyzer) readFile(node ast.Node) ([]byte, error) {
	filename := a.pass.Fset.File(node.Pos()).Name()
	content, ok := a.fileContent[filename]
	if !ok {
		var err error
		content, err = a.pass.ReadFile(filename)
		if err != nil {
			return nil, err
		}
		a.fileContent[filename] = content
	}
	return content, nil
}

// A goFixInlineFuncFact is exported for each function marked "//go:fix inline".
// It holds information about the callee to support inlining.
type goFixInlineFuncFact struct{ Callee *inline.Callee }

func (f *goFixInlineFuncFact) String() string { return "goFixInline " + f.Callee.String() }
func (*goFixInlineFuncFact) AFact()           {}

// A goFixInlineConstFact is exported for each constant marked "//go:fix inline".
// It holds information about an inlinable constant. Gob-serializable.
type goFixInlineConstFact struct {
	// Information about "const LHSName = RHSName".
	RHSName    string
	RHSPkgPath string
	RHSPkgName string
	rhsObj     types.Object // for current package
}

func (c *goFixInlineConstFact) String() string {
	return fmt.Sprintf("goFixInline const %q.%s", c.RHSPkgPath, c.RHSName)
}

func (*goFixInlineConstFact) AFact() {}

// A goFixInlineAliasFact is exported for each type alias marked "//go:fix inline".
// It holds no information; its mere existence demonstrates that an alias is inlinable.
type goFixInlineAliasFact struct{}

func (c *goFixInlineAliasFact) String() string { return "goFixInline alias" }
func (*goFixInlineAliasFact) AFact()           {}

func discard(string, ...any) {}


================================================
FILE: go/analysis/passes/inline/inline_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"slices"
	"testing"

	gocmp "github.com/google/go-cmp/cmp"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
)

func TestAnalyzer(t *testing.T) {
	if testenv.Go1Point() < 24 {
		testenv.NeedsGoExperiment(t, "aliastypeparams")
	}
	analysistest.RunWithSuggestedFixes(t, analysistest.TestData(), Analyzer, "a", "b", "rmimport")

	dir1 := testfiles.ExtractTxtarFileToTmp(t, "testdata/src/issue76190.txtar")
	analysistest.RunWithSuggestedFixes(t, dir1, Analyzer, "example.com/a", "example.com/b")

	dir2 := testfiles.ExtractTxtarFileToTmp(t, "testdata/src/issue77610.txtar")
	analysistest.RunWithSuggestedFixes(t, dir2, Analyzer,
		"example.com/a",
		"example.com/b",
		"example.com/c",
		"example.com/d",
	)
}

func TestAllowBindingDeclFlag(t *testing.T) {
	saved := allowBindingDecl
	defer func() { allowBindingDecl = saved }()

	run := func(allow bool) {
		name := fmt.Sprintf("binding_%v", allow)
		t.Run(name, func(t *testing.T) {
			allowBindingDecl = allow
			analysistest.RunWithSuggestedFixes(t, analysistest.TestData(), Analyzer, name)
		})
	}
	run(true)  // testdata/src/binding_true
	run(false) // testdata/src/binding_false
}

func TestTypesWithNames(t *testing.T) {
	// Test setup inspired by internal/analysis/addimport_test.go.
	testenv.NeedsDefaultImporter(t)

	for _, test := range []struct {
		typeExpr string
		want     []string
	}{
		{
			"int",
			[]string{"int"},
		},
		{
			"*int",
			[]string{"int"},
		},
		{
			"[]*int",
			[]string{"int"},
		},
		{
			"[2]int",
			[]string{"int"},
		},
		{
			// go/types does not expose the length expression.
			"[unsafe.Sizeof(uint(1))]int",
			[]string{"int"},
		},
		{
			"map[string]int",
			[]string{"int", "string"},
		},
		{
			"map[int]struct{x, y int}",
			[]string{"int"},
		},
		{
			"T",
			[]string{"a.T"},
		},
		{
			"iter.Seq[int]",
			[]string{"int", "iter.Seq"},
		},
		{
			"io.Reader",
			[]string{"io.Reader"},
		},
		{
			"map[*io.Writer]map[T]A",
			[]string{"a.A", "a.T", "io.Writer"},
		},
		{
			"func(int, int) (bool, error)",
			[]string{"bool", "error", "int"},
		},
		{
			"func(int, ...string) (T, *T, error)",
			[]string{"a.T", "error", "int", "string"},
		},
		{
			"func(iter.Seq[int])",
			[]string{"int", "iter.Seq"},
		},
		{
			"struct { a int; b bool}",
			[]string{"bool", "int"},
		},
		{
			"struct { io.Reader; a int}",
			[]string{"int", "io.Reader"},
		},
		{
			"map[*string]struct{x chan int; y [2]bool}",
			[]string{"bool", "int", "string"},
		},
		{
			"interface {F(int) bool}",
			[]string{"bool", "int"},
		},
		{
			"interface {io.Reader; F(int) bool}",
			[]string{"bool", "int", "io.Reader"},
		},
		{
			"G", // a type parameter of the function
			[]string{"a.G"},
		},
	} {
		src := `
			package a
			import ("io"; "iter"; "unsafe")
			func _(io.Reader, iter.Seq[int]) uintptr {return unsafe.Sizeof(1)}
			type T int
			type A = T

			func F[G any]() {
				var V ` + test.typeExpr + `
				_ = V
			}`

		// parse
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "a.go", src, 0)
		if err != nil {
			t.Errorf("%s: %v", test.typeExpr, err)
			continue
		}

		// type-check
		info := &types.Info{
			Types:     make(map[ast.Expr]types.TypeAndValue),
			Scopes:    make(map[ast.Node]*types.Scope),
			Defs:      make(map[*ast.Ident]types.Object),
			Implicits: make(map[ast.Node]types.Object),
		}
		conf := &types.Config{
			Error:    func(err error) { t.Fatalf("%s: %v", test.typeExpr, err) },
			Importer: importer.Default(),
		}
		pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, info)
		if err != nil {
			t.Errorf("%s: %v", test.typeExpr, err)
			continue
		}

		// Look at V's type.
		typ := pkg.Scope().Lookup("F").(*types.Func).
			Scope().Lookup("V").(*types.Var).Type()
		tns := typenames(typ)
		// Sort names for comparison.
		var got []string
		for _, tn := range tns {
			var prefix string
			if p := tn.Pkg(); p != nil && p.Path() != "" {
				prefix = p.Path() + "."
			}
			got = append(got, prefix+tn.Name())
		}
		slices.Sort(got)
		got = slices.Compact(got)

		if diff := gocmp.Diff(test.want, got); diff != "" {
			t.Errorf("%s: mismatch (-want, +got):\n%s", test.typeExpr, diff)
		}
	}
}


================================================
FILE: go/analysis/passes/inline/issue77844_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

import (
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/internal/testfiles"
	"testing"
)

func TestIssue77844(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, "testdata/src/issue77844.txtar")
	analysistest.Run(t, dir, Analyzer, "example.com/main")
}


================================================
FILE: go/analysis/passes/inline/testdata/src/a/a.go
================================================
package a

import "a/internal"

// Functions.

func f() {
	One() // want `Call of a.One should be inlined`

	new(T).Two() // want `Call of \(a.T\).Two should be inlined`
}

type T struct{}

//go:fix inline
func One() int { return one } // want One:`goFixInline a.One`

const one = 1

//go:fix inline
func (T) Two() int { return 2 } // want Two:`goFixInline \(a.T\).Two`

// Constants.

const Uno = 1

//go:fix inline
const In1 = Uno // want In1: `goFixInline const "a".Uno`

const (
	no1 = one

	//go:fix inline
	In2 = one // want In2: `goFixInline const "a".one`
)

//go:fix inline
const (
	in3  = one
	in4  = one
	bad1 = 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`
)

//go:fix inline
const in5,
	in6,
	bad2 = one, one,
	one + 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

// Make sure we don't crash on iota consts, but still process the whole decl.
//
//go:fix inline
const (
	a = iota // want `invalid //go:fix inline directive: const value is iota`
	b
	in7 = one
)

func _() {
	x := In1 // want `Constant In1 should be inlined`
	x = In2  // want `Constant In2 should be inlined`
	x = in3  // want `Constant in3 should be inlined`
	x = in4  // want `Constant in4 should be inlined`
	x = in5  // want `Constant in5 should be inlined`
	x = in6  // want `Constant in6 should be inlined`
	x = in7  // want `Constant in7 should be inlined`
	x = no1
	_ = x

	in1 := 1 // don't inline lvalues
	_ = in1
}

const (
	x = 1
	//go:fix inline
	in8 = x
)

//go:fix inline
const D = internal.D // want D: `goFixInline const "a/internal".D`

func shadow() {
	var x int // shadows x at package scope

	//go:fix inline
	const a = iota // want `invalid //go:fix inline directive: const value is iota`

	const iota = 2
	// Below this point, iota is an ordinary constant.

	//go:fix inline
	const b = iota

	x = a // a is defined with the predeclared iota, so it cannot be inlined
	x = b // want `Constant b should be inlined`

	// Don't offer to inline in8, because the result, "x", would mean something different
	// in this scope than it does in the scope where in8 is defined.
	x = in8

	_ = x
}

// Type aliases

//go:fix inline
type A = T // want A: `goFixInline alias`

var _ A // want `Type alias A should be inlined`

//go:fix inline
type AA = // want AA: `goFixInline alias`
A         // want `Type alias A should be inlined`

var _ AA // want `Type alias AA should be inlined`

//go:fix inline
type (
	B = []T                 // want B: `goFixInline alias`
	C = map[*string][]error // want C: `goFixInline alias`
)

var _ B // want `Type alias B should be inlined`
var _ C // want `Type alias C should be inlined`

//go:fix inline
type E = map[[Uno]string][]*T // want `invalid //go:fix inline directive: array types not supported`

var _ E // nothing should happen here

// literal array lengths are OK
//
//go:fix inline
type EL = map[[2]string][]*T // want EL: `goFixInline alias`

var _ EL // want `Type alias EL should be inlined`

//go:fix inline
type F = map[internal.T]T // want F: `goFixInline alias`

var _ F // want `Type alias F should be inlined`

//go:fix inline
type G = []chan *internal.T // want G: `goFixInline alias`

var _ G // want `Type alias G should be inlined`

// local shadowing
func _() {
	type string = int
	const T = 1

	var _ B // nope: B's RHS contains T, which is shadowed
	var _ C // nope: C's RHS contains string, which is shadowed
}

// local inlining
func _[P any]() {
	const a = 1
	//go:fix inline
	const b = a

	x := b // want `Constant b should be inlined`

	//go:fix inline
	type u = []P

	var y u // want `Type alias u should be inlined`

	_ = x
	_ = y
}

// generic type aliases

//go:fix inline
type (
	Mapset[T comparable] = map[T]bool // want Mapset: `goFixInline alias`
	Pair[X, Y any]       = struct {   // want Pair: `goFixInline alias`
		X X
		Y Y
	}
)

var _ Mapset[int] // want `Type alias Mapset\[int\] should be inlined`

var _ Pair[T, string] // want `Type alias Pair\[T, string\] should be inlined`

func _[V any]() {
	//go:fix inline
	type M[K comparable] = map[K]V

	var _ M[int] // want `Type alias M\[int\] should be inlined`
}


================================================
FILE: go/analysis/passes/inline/testdata/src/a/a.go.golden
================================================
package a

import "a/internal"

// Functions.

func f() {
	_ = one // want `Call of a.One should be inlined`

	_ = 2 // want `Call of \(a.T\).Two should be inlined`
}

type T struct{}

//go:fix inline
func One() int { return one } // want One:`goFixInline a.One`

const one = 1

//go:fix inline
func (T) Two() int { return 2 } // want Two:`goFixInline \(a.T\).Two`

// Constants.

const Uno = 1

//go:fix inline
const In1 = Uno // want In1: `goFixInline const "a".Uno`

const (
	no1 = one

	//go:fix inline
	In2 = one // want In2: `goFixInline const "a".one`
)

//go:fix inline
const (
	in3  = one
	in4  = one
	bad1 = 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`
)

//go:fix inline
const in5,
	in6,
	bad2 = one, one,
	one + 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

// Make sure we don't crash on iota consts, but still process the whole decl.
//
//go:fix inline
const (
	a = iota // want `invalid //go:fix inline directive: const value is iota`
	b
	in7 = one
)

func _() {
	x := Uno // want `Constant In1 should be inlined`
	x = one  // want `Constant In2 should be inlined`
	x = one  // want `Constant in3 should be inlined`
	x = one  // want `Constant in4 should be inlined`
	x = one  // want `Constant in5 should be inlined`
	x = one  // want `Constant in6 should be inlined`
	x = one  // want `Constant in7 should be inlined`
	x = no1
	_ = x

	in1 := 1 // don't inline lvalues
	_ = in1
}

const (
	x = 1
	//go:fix inline
	in8 = x
)

//go:fix inline
const D = internal.D // want D: `goFixInline const "a/internal".D`

func shadow() {
	var x int // shadows x at package scope

	//go:fix inline
	const a = iota // want `invalid //go:fix inline directive: const value is iota`

	const iota = 2
	// Below this point, iota is an ordinary constant.

	//go:fix inline
	const b = iota

	x = a // a is defined with the predeclared iota, so it cannot be inlined
	x = iota // want `Constant b should be inlined`

	// Don't offer to inline in8, because the result, "x", would mean something different
	// in this scope than it does in the scope where in8 is defined.
	x = in8

	_ = x
}

// Type aliases

//go:fix inline
type A = T // want A: `goFixInline alias`

var _ T // want `Type alias A should be inlined`

//go:fix inline
type AA = // want AA: `goFixInline alias`
T         // want `Type alias A should be inlined`

var _ A // want `Type alias AA should be inlined`

//go:fix inline
type (
	B = []T                 // want B: `goFixInline alias`
	C = map[*string][]error // want C: `goFixInline alias`
)

var _ []T // want `Type alias B should be inlined`
var _ map[*string][]error // want `Type alias C should be inlined`

//go:fix inline
type E = map[[Uno]string][]*T // want `invalid //go:fix inline directive: array types not supported`

var _ E // nothing should happen here

// literal array lengths are OK
//
//go:fix inline
type EL = map[[2]string][]*T // want EL: `goFixInline alias`

var _ map[[2]string][]*T // want `Type alias EL should be inlined`

//go:fix inline
type F = map[internal.T]T // want F: `goFixInline alias`

var _ map[internal.T]T // want `Type alias F should be inlined`

//go:fix inline
type G = []chan *internal.T // want G: `goFixInline alias`

var _ []chan *internal.T // want `Type alias G should be inlined`

// local shadowing
func _() {
	type string = int
	const T = 1

	var _ B // nope: B's RHS contains T, which is shadowed
	var _ C // nope: C's RHS contains string, which is shadowed
}


// local inlining
func _[P any]() {
	const a = 1
	//go:fix inline
	const b = a

	x := a // want `Constant b should be inlined`

	//go:fix inline
	type u = []P

	var y []P // want `Type alias u should be inlined`

	_ = x
	_ = y
}

// generic type aliases

//go:fix inline
type (
	Mapset[T comparable] = map[T]bool // want Mapset: `goFixInline alias`
	Pair[X, Y any]       = struct {   // want Pair: `goFixInline alias`
		X X
		Y Y
	}
)

var _ map[int]bool // want `Type alias Mapset\[int\] should be inlined`

var _ struct {
	X T
	Y string
} // want `Type alias Pair\[T, string\] should be inlined`

func _[V any]() {
	//go:fix inline
	type M[K comparable] = map[K]V

	var _ map[int]V // want `Type alias M\[int\] should be inlined`
}


================================================
FILE: go/analysis/passes/inline/testdata/src/a/internal/d.go
================================================
// According to the go toolchain's rule about internal packages,
// this package is visible to package a, but not package b.
package internal

const D = 1

type T int


================================================
FILE: go/analysis/passes/inline/testdata/src/b/b.go
================================================
package b

import "a"
import . "c"

func f() {
	a.One() // want `cannot inline call to a.One because body refers to non-exported one`

	new(a.T).Two() // want `Call of \(a.T\).Two should be inlined`
}

//go:fix inline
const in2 = a.Uno

//go:fix inline
const in3 = C // c.C, by dot import

func g() {
	x := a.In1 // want `Constant a\.In1 should be inlined`

	a := 1
	// Although the package identifier "a" is shadowed here,
	// a second import of "a" will be added with a new package identifer.
	x = in2 // want `Constant in2 should be inlined`

	x = in3 // want `Constant in3 should be inlined`

	_ = a
	_ = x
}

const d = a.D // nope: a.D refers to a constant in a package that is not visible here.

var _ a.A // want `Type alias a\.A should be inlined`
var _ a.B // want `Type alias a\.B should be inlined`
var _ a.C // want `Type alias a\.C should be inlined`
var _ R   // want `Type alias R should be inlined`

var _ a.G // nope: a.G refers to a type in a package that is not visible here


================================================
FILE: go/analysis/passes/inline/testdata/src/b/b.go.golden
================================================
package b

import a0 "a"

import "io"

import "a"
import . "c"

func f() {
	a.One() // want `cannot inline call to a.One because body refers to non-exported one`

	_ = 2 // want `Call of \(a.T\).Two should be inlined`
}

//go:fix inline
const in2 = a.Uno

//go:fix inline
const in3 = C // c.C, by dot import

func g() {
	x := a.Uno // want `Constant a\.In1 should be inlined`

	a := 1
	// Although the package identifier "a" is shadowed here,
	// a second import of "a" will be added with a new package identifer.
	x = a0.Uno // want `Constant in2 should be inlined`

	x = C // want `Constant in3 should be inlined`

	_ = a
	_ = x
}

const d = a.D // nope: a.D refers to a constant in a package that is not visible here.

var _ a.T                     // want `Type alias a\.A should be inlined`
var _ []a.T                   // want `Type alias a\.B should be inlined`
var _ map[*string][]error     // want `Type alias a\.C should be inlined`
var _ map[io.Reader]io.Reader // want `Type alias R should be inlined`

var _ a.G  // nope: a.G refers to a type in a package that is not visible here


================================================
FILE: go/analysis/passes/inline/testdata/src/binding_false/a.go
================================================
package a

//go:fix inline
func f(x, y int) int { // want f:`goFixInline a.f`
	return y + x
}

func g() {
	f(1, 2) // want `Call of a.f should be inlined`

	f(h(1), h(2))
}

func h(int) int


================================================
FILE: go/analysis/passes/inline/testdata/src/binding_false/a.go.golden
================================================
package a

//go:fix inline
func f(x, y int) int { // want f:`goFixInline a.f`
	return y + x
}

func g() {
	_ = 2 + 1 // want `Call of a.f should be inlined`

	f(h(1), h(2))
}

func h(int) int


================================================
FILE: go/analysis/passes/inline/testdata/src/binding_true/a.go
================================================
package a

//go:fix inline
func f(x, y int) int { // want f:`goFixInline a.f`
	return y + x
}

func g() {
	f(1, 2) // want `Call of a.f should be inlined`

	f(h(1), h(2)) // want `Call of a.f should be inlined`
}

func h(int) int


================================================
FILE: go/analysis/passes/inline/testdata/src/binding_true/a.go.golden
================================================
package a

//go:fix inline
func f(x, y int) int { // want f:`goFixInline a.f`
	return y + x
}

func g() {
	_ = 2 + 1 // want `Call of a.f should be inlined`

	var x int = h(1)
	_ = h(2) + x // want `Call of a.f should be inlined`
}

func h(int) int


================================================
FILE: go/analysis/passes/inline/testdata/src/c/c.go
================================================
package c

// This package is dot-imported by package b.

import "io"

const C = 1

//go:fix inline
type R = map[io.Reader]io.Reader


================================================
FILE: go/analysis/passes/inline/testdata/src/directive/directive.go
================================================
package directive

// Functions.

func f() {
	One()

	new(T).Two()
}

type T struct{}

//go:fix inline
func One() int { return one } // want One:`goFixInline directive.One`

const one = 1

//go:fix inline
func (T) Two() int { return 2 } // want Two:`goFixInline \(directive.T\).Two`

// Constants.

const Uno = 1

//go:fix inline
const In1 = Uno // want In1: `goFixInline const "directive".Uno`

const (
	no1 = one

	//go:fix inline
	In2 = one // want In2: `goFixInline const "directive".one`
)

//go:fix inline
const bad1 = 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

//go:fix inline
const in5,
	in6,
	bad2 = one, one,
	one + 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

// Make sure we don't crash on iota consts, but still process the whole decl.
//
//go:fix inline
const (
	a = iota // want `invalid //go:fix inline directive: const value is iota`
	b
	in7 = one
)

const (
	x = 1
	//go:fix inline
	in8 = x
)

//go:fix inline
const in9 = iota // want `invalid //go:fix inline directive: const value is iota`

//go:fix inline
type E = map[[Uno]string][]*T // want `invalid //go:fix inline directive: array types not supported`


================================================
FILE: go/analysis/passes/inline/testdata/src/directive/directive.go.golden
================================================
package golden

import "a/internal"

// Functions.

func f() {
	One()

	new(T).Two()
}

type T struct{}

//go:fix inline
func One() int { return one }

const one = 1

//go:fix inline
func (T) Two() int { return 2 }

// Constants.

const Uno = 1

//go:fix inline
const In1 = Uno // want In1: `goFixInline const "a".Uno`

const (
	no1 = one

	//go:fix inline
	In2 = one // want In2: `goFixInline const "a".one`
)

//go:fix inline
const bad1 = 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

//go:fix inline
const in5,
	in6,
	bad2 = one, one,
	one + 1 // want `invalid //go:fix inline directive: const value is not the name of another constant`

// Make sure we don't crash on iota consts, but still process the whole decl.
//
//go:fix inline
const (
	a = iota // want `invalid //go:fix inline directive: const value is iota`
	b
	in7 = one
)

const (
	x = 1
	//go:fix inline
	in8 = x
)

//go:fix inline
const a = iota // want `invalid //go:fix inline directive: const value is iota`

//go:fix inline
type E = map[[Uno]string][]*T // want `invalid //go:fix inline directive: array types not supported`

// literal array lengths are OK
//
//go:fix inline
type EL = map[[2]string][]*T // want EL: `goFixInline alias`


================================================
FILE: go/analysis/passes/inline/testdata/src/issue76190.txtar
================================================
This test checks that calls are not inlined when the call appears in a specific
test of the function. (Even deprecated functions deserve tests.)

Variants:
- functions (TestF) vs methods (TestT_F)
- optional comment suffixes (TestSYMBOL_comment)
- in-package test vs external test
- test of same or different package from symbol

-- go.mod --
module example.com

-- a/a.go --
package a

//go:fix inline
func F() { print("F") } // want F:"goFixInline a.F"
//go:fix inline
func G() { print("G") } // want G:"goFixInline a.G"

type T int
//go:fix inline
func (T) F() { print("T.F") } // want F:`goFixInline \(a.T\).F`
//go:fix inline
func (T) G() { print("T.G") } // want G:`goFixInline \(a.T\).G`

-- a/a_test.go --
package a

import "testing"

func TestF(t *testing.T) {
	F() // not inlined
	G() // want "Call of a.G should be inlined"
}

func TestG_comment(t *testing.T) {
	F() // want "Call of a.F should be inlined"
	G() // not inlined
}

func TestT_F(t *testing.T) {
	T(0).F() // not inlined
	T(0).G() // want `Call of \(a.T\).G should be inlined`
}

func TestT_G(t *testing.T) {
	T(0).F() // want `Call of \(a.T\).F should be inlined`
	T(0).G() // not inlined
}

-- a/a_test.go.golden --
package a

import "testing"

func TestF(t *testing.T) {
	F()        // not inlined
	print("G") // want "Call of a.G should be inlined"
}

func TestG_comment(t *testing.T) {
	print("F") // want "Call of a.F should be inlined"
	G()        // not inlined
}

func TestT_F(t *testing.T) {
	T(0).F()     // not inlined
	print("T.G") // want `Call of \(a.T\).G should be inlined`
}

func TestT_G(t *testing.T) {
	print("T.F") // want `Call of \(a.T\).F should be inlined`
	T(0).G()     // not inlined
}

-- a/a_x_test.go --
package a_test

import (
	"example.com/a"
	"testing"
)

func TestF(t *testing.T) {
	a.F() // not inlined
	a.G() // want "Call of a.G should be inlined"
}

func TestG_comment(t *testing.T) {
	a.F() // want "Call of a.F should be inlined"
	a.G() // not inlined
}

func TestT_F(t *testing.T) {
	a.T(0).F() // not inlined
	a.T(0).G() // want `Call of \(a.T\).G should be inlined`
}

func TestT_G(t *testing.T) {
	a.T(0).F() // want `Call of \(a.T\).F should be inlined`
	a.T(0).G() // not inlined
}

-- a/a_x_test.go.golden --
package a_test

import (
	"example.com/a"
	"testing"
)

func TestF(t *testing.T) {
	a.F() 	   // not inlined
	print("G") // want "Call of a.G should be inlined"
}

func TestG_comment(t *testing.T) {
	print("F") // want "Call of a.F should be inlined"
	a.G()      // not inlined
}

func TestT_F(t *testing.T) {
	a.T(0).F()   // not inlined
	print("T.G") // want `Call of \(a.T\).G should be inlined`
}

func TestT_G(t *testing.T) {
	print("T.F") // want `Call of \(a.T\).F should be inlined`
	a.T(0).G()   // not inlined
}

-- b/b_test.go --
package b_test

import (
	"example.com/a"
	"testing"
)

func TestF(t *testing.T) {
	a.F() // want "Call of a.F should be inlined"
}

-- b/b_test.go.golden --
package b_test

import (
	"testing"
)

func TestF(t *testing.T) {
	print("F") // want "Call of a.F should be inlined"
}


================================================
FILE: go/analysis/passes/inline/testdata/src/issue77610.txtar
================================================
This test verifies that unused imports conservatively added by the inliner are
removed in FormatSourceRemoveImports.

-- go.mod --
module example.com

-- a/a.go --
package a

import "io"

//go:fix inline
func OldHello(w io.Writer) error { // want OldHello:"goFixInline a.OldHello"
	return NewHello(w)
}

func NewHello(w io.Writer) error {
	_, err := w.Write([]byte("Hello, World!"))
	return err
}

-- b/b.go --
package b

import (
	"strings"
	"example.com/a"
)

func _() {
    var buf strings.Builder
	// The inliner wants to add an import for "io"; make sure post-processing of the fix removes it.
	a.OldHello(&buf) // want "Call of a.OldHello should be inlined"
}

-- b/b.go.golden --
package b

import (
	"strings"
	"example.com/a"
)

func _() {
    var buf strings.Builder
	// The inliner wants to add an import for "io"; make sure post-processing of the fix removes it.
	a.NewHello(&buf) // want "Call of a.OldHello should be inlined"
}

-- c/c.go --
package c

import "encoding/json"

//go:fix inline
func OldProcess(m json.Marshaler) error { // want OldProcess:"goFixInline c.OldProcess"
	return NewProcess(m)
}

func NewProcess(m json.Marshaler) error {
	_, err := m.MarshalJSON()
	return err
}

-- d/d.go --
package d

import (
	"time"

	"example.com/c"
)

func _() {
	t := time.Now()
	// The inliner wants to add an import for "encoding/json"; make sure post-processing of the fix removes it.
	c.OldProcess(t) // want "Call of c.OldProcess should be inlined"
}

-- d/d.go.golden --
package d

import (
	"time"

	"example.com/c"
)

func _() {
	t := time.Now()
	// The inliner wants to add an import for "encoding/json"; make sure post-processing of the fix removes it.
	c.NewProcess(t) // want "Call of c.OldProcess should be inlined"
}


================================================
FILE: go/analysis/passes/inline/testdata/src/issue77844.txtar
================================================
-- go.mod --
module example.com

go 1.24

-- lib/lib.go --
package lib

//go:fix inline
type Alias[T any] = []T

-- other/other.go --
package other

type Other int

-- main/main.go --
package main

import (
	"example.com/lib"
	"example.com/other"
)

func _() {
	var _ lib.Alias[other.Other] // want "Type alias lib.Alias.other.Other. should be inlined"
}


================================================
FILE: go/analysis/passes/inline/testdata/src/rmimport/rmimport.go
================================================
package rmimport

import "a"

// Test that application of two fixes that each remove the second-last
// import of "a" results in removal of the import. This is implemented
// by the general analysis fix logic, not by any one analyzer.
func _() {
	print(a.T{}.Two()) // want `should be inlined`
	print(a.T{}.Two()) // want `should be inlined`
}


================================================
FILE: go/analysis/passes/inline/testdata/src/rmimport/rmimport.go.golden
================================================
package rmimport

// Test that application of two fixes that each remove the second-last
// import of "a" results in removal of the import. This is implemented
// by the general analysis fix logic, not by any one analyzer.
func _() {
	print(2) // want `should be inlined`
	print(2) // want `should be inlined`
}


================================================
FILE: go/analysis/passes/inspect/inspect.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package inspect defines an Analyzer that provides an AST inspector
// (golang.org/x/tools/go/ast/inspector.Inspector) for the syntax trees
// of a package. It is only a building block for other analyzers.
//
// Example of use in another analysis:
//
//	import (
//		"golang.org/x/tools/go/analysis"
//		"golang.org/x/tools/go/analysis/passes/inspect"
//		"golang.org/x/tools/go/ast/inspector"
//	)
//
//	var Analyzer = &analysis.Analyzer{
//		...
//		Requires:       []*analysis.Analyzer{inspect.Analyzer},
//	}
//
//	func run(pass *analysis.Pass) (interface{}, error) {
//		inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
//		inspect.Preorder(nil, func(n ast.Node) {
//			...
//		})
//		return nil, nil
//	}
package inspect

import (
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/inspector"
)

var Analyzer = &analysis.Analyzer{
	Name:             "inspect",
	Doc:              "optimize AST traversal for later passes",
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/inspect",
	Run:              run,
	RunDespiteErrors: true,
	ResultType:       reflect.TypeFor[*inspector.Inspector](),
}

func run(pass *analysis.Pass) (any, error) {
	return inspector.New(pass.Files), nil
}


================================================
FILE: go/analysis/passes/internal/gofixdirective/gofixdirective.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gofixdirective searches for and validates go:fix directives. The
// go/analysis/passes/inline package uses findgofix to perform inlining.
// The go/analysis/passes/gofix package uses findgofix to check for problems
// with go:fix directives.
//
// gofixdirective is separate from gofix to avoid depending on refactor/inline,
// which is large.
package gofixdirective

// This package is tested by go/analysis/passes/inline.

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/inspector"
	internalastutil "golang.org/x/tools/internal/astutil"
)

// A Handler handles language entities with go:fix directives.
type Handler interface {
	HandleFunc(*ast.FuncDecl)
	HandleAlias(*ast.TypeSpec)
	HandleConst(name, rhs *ast.Ident)
}

// Find finds functions and constants annotated with an appropriate "//go:fix"
// comment (the syntax proposed by #32816), and calls handler methods for each one.
// h may be nil.
func Find(pass *analysis.Pass, root inspector.Cursor, h Handler) {
	for cur := range root.Preorder((*ast.FuncDecl)(nil), (*ast.GenDecl)(nil)) {
		switch decl := cur.Node().(type) {
		case *ast.FuncDecl:
			findFunc(decl, h)

		case *ast.GenDecl:
			if decl.Tok != token.CONST && decl.Tok != token.TYPE {
				continue
			}
			declInline := hasFixInline(decl.Doc)
			// Accept inline directives on the entire decl as well as individual specs.
			for _, spec := range decl.Specs {
				switch spec := spec.(type) {
				case *ast.TypeSpec: // Tok == TYPE
					findAlias(pass, spec, declInline, h)

				case *ast.ValueSpec: // Tok == CONST
					findConst(pass, spec, declInline, h)
				}
			}
		}
	}
}

func findFunc(decl *ast.FuncDecl, h Handler) {
	if !hasFixInline(decl.Doc) {
		return
	}
	if h != nil {
		h.HandleFunc(decl)
	}
}

func findAlias(pass *analysis.Pass, spec *ast.TypeSpec, declInline bool, h Handler) {
	if !declInline && !hasFixInline(spec.Doc) {
		return
	}
	if !spec.Assign.IsValid() {
		pass.Reportf(spec.Pos(), "invalid //go:fix inline directive: not a type alias")
		return
	}

	// Disallow inlines of type expressions containing array types.
	// Given an array type like [N]int where N is a named constant, go/types provides
	// only the value of the constant as an int64. So inlining A in this code:
	//
	//    const N = 5
	//    type A = [N]int
	//
	// would result in [5]int, breaking the connection with N.
	for n := range ast.Preorder(spec.Type) {
		if ar, ok := n.(*ast.ArrayType); ok && ar.Len != nil {
			// Make an exception when the array length is a literal int.
			if lit, ok := ast.Unparen(ar.Len).(*ast.BasicLit); ok && lit.Kind == token.INT {
				continue
			}
			pass.Reportf(spec.Pos(), "invalid //go:fix inline directive: array types not supported")
			return
		}
	}
	if h != nil {
		h.HandleAlias(spec)
	}
}

func findConst(pass *analysis.Pass, spec *ast.ValueSpec, declInline bool, h Handler) {
	specInline := hasFixInline(spec.Doc)
	if declInline || specInline {
		for i, nameIdent := range spec.Names {
			if i >= len(spec.Values) {
				// Possible following an iota.
				break
			}
			var rhsIdent *ast.Ident
			switch val := spec.Values[i].(type) {
			case *ast.Ident:
				// Constants defined with the predeclared iota cannot be inlined.
				if pass.TypesInfo.Uses[val] == builtinIota {
					pass.Reportf(val.Pos(), "invalid //go:fix inline directive: const value is iota")
					return
				}
				rhsIdent = val
			case *ast.SelectorExpr:
				rhsIdent = val.Sel
			default:
				pass.Reportf(val.Pos(), "invalid //go:fix inline directive: const value is not the name of another constant")
				return
			}
			if h != nil {
				h.HandleConst(nameIdent, rhsIdent)
			}
		}
	}
}

// hasFixInline reports the presence of a "//go:fix inline" directive
// in the comments.
func hasFixInline(cg *ast.CommentGroup) bool {
	for _, d := range internalastutil.Directives(cg) {
		if d.Tool == "go" && d.Name == "fix" && d.Args == "inline" {
			return true
		}
	}
	return false
}

var builtinIota = types.Universe.Lookup("iota")


================================================
FILE: go/analysis/passes/loopclosure/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package loopclosure defines an Analyzer that checks for references to
// enclosing loop variables from within nested functions.
//
// # Analyzer loopclosure
//
// loopclosure: check references to loop variables from within nested functions
//
// This analyzer reports places where a function literal references the
// iteration variable of an enclosing loop, and the loop calls the function
// in such a way (e.g. with go or defer) that it may outlive the loop
// iteration and possibly observe the wrong value of the variable.
//
// Note: An iteration variable can only outlive a loop iteration in Go versions <=1.21.
// In Go 1.22 and later, the loop variable lifetimes changed to create a new
// iteration variable per loop iteration. (See go.dev/issue/60078.)
//
// In this example, all the deferred functions run after the loop has
// completed, so all observe the final value of v [<go1.22].
//
//	for _, v := range list {
//	    defer func() {
//	        use(v) // incorrect
//	    }()
//	}
//
// One fix is to create a new variable for each iteration of the loop:
//
//	for _, v := range list {
//	    v := v // new var per iteration
//	    defer func() {
//	        use(v) // ok
//	    }()
//	}
//
// After Go version 1.22, the previous two for loops are equivalent
// and both are correct.
//
// The next example uses a go statement and has a similar problem [<go1.22].
// In addition, it has a data race because the loop updates v
// concurrent with the goroutines accessing it.
//
//	for _, v := range elem {
//	    go func() {
//	        use(v)  // incorrect, and a data race
//	    }()
//	}
//
// A fix is the same as before. The checker also reports problems
// in goroutines started by golang.org/x/sync/errgroup.Group.
// A hard-to-spot variant of this form is common in parallel tests:
//
//	func Test(t *testing.T) {
//	    for _, test := range tests {
//	        t.Run(test.name, func(t *testing.T) {
//	            t.Parallel()
//	            use(test) // incorrect, and a data race
//	        })
//	    }
//	}
//
// The t.Parallel() call causes the rest of the function to execute
// concurrent with the loop [<go1.22].
//
// The analyzer reports references only in the last statement,
// as it is not deep enough to understand the effects of subsequent
// statements that might render the reference benign.
// ("Last statement" is defined recursively in compound
// statements such as if, switch, and select.)
//
// See: https://golang.org/doc/go_faq.html#closures_and_goroutines
package loopclosure


================================================
FILE: go/analysis/passes/loopclosure/loopclosure.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package loopclosure

import (
	_ "embed"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "loopclosure",
	Doc:      analyzerutil.MustExtractDoc(doc, "loopclosure"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/loopclosure",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.File)(nil),
		(*ast.RangeStmt)(nil),
		(*ast.ForStmt)(nil),
	}
	inspect.Nodes(nodeFilter, func(n ast.Node, push bool) bool {
		if !push {
			// inspect.Nodes is slightly suboptimal as we only use push=true.
			return true
		}
		// Find the variables updated by the loop statement.
		var vars []types.Object
		addVar := func(expr ast.Expr) {
			if id, _ := expr.(*ast.Ident); id != nil {
				if obj := pass.TypesInfo.ObjectOf(id); obj != nil {
					vars = append(vars, obj)
				}
			}
		}
		var body *ast.BlockStmt
		switch n := n.(type) {
		case *ast.File:
			// Only traverse the file if its goversion is strictly before go1.22.
			return !analyzerutil.FileUsesGoVersion(pass, n, versions.Go1_22)

		case *ast.RangeStmt:
			body = n.Body
			addVar(n.Key)
			addVar(n.Value)
		case *ast.ForStmt:
			body = n.Body
			switch post := n.Post.(type) {
			case *ast.AssignStmt:
				// e.g. for p = head; p != nil; p = p.next
				for _, lhs := range post.Lhs {
					addVar(lhs)
				}
			case *ast.IncDecStmt:
				// e.g. for i := 0; i < n; i++
				addVar(post.X)
			}
		}
		if vars == nil {
			return true
		}

		// Inspect statements to find function literals that may be run outside of
		// the current loop iteration.
		//
		// For go, defer, and errgroup.Group.Go, we ignore all but the last
		// statement, because it's hard to prove go isn't followed by wait, or
		// defer by return. "Last" is defined recursively.
		//
		// TODO: consider allowing the "last" go/defer/Go statement to be followed by
		// N "trivial" statements, possibly under a recursive definition of "trivial"
		// so that checker could, for example, conclude that a go statement is
		// followed by an if statement made of only trivial statements and trivial expressions,
		// and hence the go statement could still be checked.
		forEachLastStmt(body.List, func(last ast.Stmt) {
			var stmts []ast.Stmt
			switch s := last.(type) {
			case *ast.GoStmt:
				stmts = litStmts(s.Call.Fun)
			case *ast.DeferStmt:
				stmts = litStmts(s.Call.Fun)
			case *ast.ExprStmt: // check for errgroup.Group.Go
				if call, ok := s.X.(*ast.CallExpr); ok {
					stmts = litStmts(goInvoke(pass.TypesInfo, call))
				}
			}
			for _, stmt := range stmts {
				reportCaptured(pass, vars, stmt)
			}
		})

		// Also check for testing.T.Run (with T.Parallel).
		// We consider every t.Run statement in the loop body, because there is
		// no commonly used mechanism for synchronizing parallel subtests.
		// It is of course theoretically possible to synchronize parallel subtests,
		// though such a pattern is likely to be exceedingly rare as it would be
		// fighting against the test runner.
		for _, s := range body.List {
			switch s := s.(type) {
			case *ast.ExprStmt:
				if call, ok := s.X.(*ast.CallExpr); ok {
					for _, stmt := range parallelSubtest(pass.TypesInfo, call) {
						reportCaptured(pass, vars, stmt)
					}

				}
			}
		}
		return true
	})
	return nil, nil
}

// reportCaptured reports a diagnostic stating a loop variable
// has been captured by a func literal if checkStmt has escaping
// references to vars. vars is expected to be variables updated by a loop statement,
// and checkStmt is expected to be a statements from the body of a func literal in the loop.
func reportCaptured(pass *analysis.Pass, vars []types.Object, checkStmt ast.Stmt) {
	ast.Inspect(checkStmt, func(n ast.Node) bool {
		id, ok := n.(*ast.Ident)
		if !ok {
			return true
		}
		obj := pass.TypesInfo.Uses[id]
		if obj == nil {
			return true
		}
		for _, v := range vars {
			if v == obj {
				pass.ReportRangef(id, "loop variable %s captured by func literal", id.Name)
			}
		}
		return true
	})
}

// forEachLastStmt calls onLast on each "last" statement in a list of statements.
// "Last" is defined recursively so, for example, if the last statement is
// a switch statement, then each switch case is also visited to examine
// its last statements.
func forEachLastStmt(stmts []ast.Stmt, onLast func(last ast.Stmt)) {
	if len(stmts) == 0 {
		return
	}

	s := stmts[len(stmts)-1]
	switch s := s.(type) {
	case *ast.IfStmt:
	loop:
		for {
			forEachLastStmt(s.Body.List, onLast)
			switch e := s.Else.(type) {
			case *ast.BlockStmt:
				forEachLastStmt(e.List, onLast)
				break loop
			case *ast.IfStmt:
				s = e
			case nil:
				break loop
			}
		}
	case *ast.ForStmt:
		forEachLastStmt(s.Body.List, onLast)
	case *ast.RangeStmt:
		forEachLastStmt(s.Body.List, onLast)
	case *ast.SwitchStmt:
		for _, c := range s.Body.List {
			cc := c.(*ast.CaseClause)
			forEachLastStmt(cc.Body, onLast)
		}
	case *ast.TypeSwitchStmt:
		for _, c := range s.Body.List {
			cc := c.(*ast.CaseClause)
			forEachLastStmt(cc.Body, onLast)
		}
	case *ast.SelectStmt:
		for _, c := range s.Body.List {
			cc := c.(*ast.CommClause)
			forEachLastStmt(cc.Body, onLast)
		}
	default:
		onLast(s)
	}
}

// litStmts returns all statements from the function body of a function
// literal.
//
// If fun is not a function literal, it returns nil.
func litStmts(fun ast.Expr) []ast.Stmt {
	lit, _ := fun.(*ast.FuncLit)
	if lit == nil {
		return nil
	}
	return lit.Body.List
}

// goInvoke returns a function expression that would be called asynchronously
// (but not awaited) in another goroutine as a consequence of the call.
// For example, given the g.Go call below, it returns the function literal expression.
//
//	import "sync/errgroup"
//	var g errgroup.Group
//	g.Go(func() error { ... })
//
// Currently only "golang.org/x/sync/errgroup.Group()" is considered.
func goInvoke(info *types.Info, call *ast.CallExpr) ast.Expr {
	if !isMethodCall(info, call, "golang.org/x/sync/errgroup", "Group", "Go") {
		return nil
	}
	return call.Args[0]
}

// parallelSubtest returns statements that can be easily proven to execute
// concurrently via the go test runner, as t.Run has been invoked with a
// function literal that calls t.Parallel.
//
// In practice, users rely on the fact that statements before the call to
// t.Parallel are synchronous. For example by declaring test := test inside the
// function literal, but before the call to t.Parallel.
//
// Therefore, we only flag references in statements that are obviously
// dominated by a call to t.Parallel. As a simple heuristic, we only consider
// statements following the final labeled statement in the function body, to
// avoid scenarios where a jump would cause either the call to t.Parallel or
// the problematic reference to be skipped.
//
//	import "testing"
//
//	func TestFoo(t *testing.T) {
//		tests := []int{0, 1, 2}
//		for i, test := range tests {
//			t.Run("subtest", func(t *testing.T) {
//				println(i, test) // OK
//		 		t.Parallel()
//				println(i, test) // Not OK
//			})
//		}
//	}
func parallelSubtest(info *types.Info, call *ast.CallExpr) []ast.Stmt {
	if !isMethodCall(info, call, "testing", "T", "Run") {
		return nil
	}

	if len(call.Args) != 2 {
		// Ignore calls such as t.Run(fn()).
		return nil
	}

	lit, _ := call.Args[1].(*ast.FuncLit)
	if lit == nil {
		return nil
	}

	// Capture the *testing.T object for the first argument to the function
	// literal.
	if len(lit.Type.Params.List[0].Names) == 0 {
		return nil
	}

	tObj := info.Defs[lit.Type.Params.List[0].Names[0]]
	if tObj == nil {
		return nil
	}

	// Match statements that occur after a call to t.Parallel following the final
	// labeled statement in the function body.
	//
	// We iterate over lit.Body.List to have a simple, fast and "frequent enough"
	// dominance relationship for t.Parallel(): lit.Body.List[i] dominates
	// lit.Body.List[j] for i < j unless there is a jump.
	var stmts []ast.Stmt
	afterParallel := false
	for _, stmt := range lit.Body.List {
		stmt, labeled := unlabel(stmt)
		if labeled {
			// Reset: naively we don't know if a jump could have caused the
			// previously considered statements to be skipped.
			stmts = nil
			afterParallel = false
		}

		if afterParallel {
			stmts = append(stmts, stmt)
			continue
		}

		// Check if stmt is a call to t.Parallel(), for the correct t.
		exprStmt, ok := stmt.(*ast.ExprStmt)
		if !ok {
			continue
		}
		call, ok := exprStmt.X.(*ast.CallExpr)
		if !ok {
			continue
		}
		if isMethodCall(info, call, "testing", "T", "Parallel") {
			x, _ := call.Fun.(*ast.SelectorExpr)
			if x == nil {
				continue
			}
			id, _ := x.X.(*ast.Ident)
			if id == nil {
				continue
			}
			if info.Uses[id] == tObj {
				afterParallel = true
			}
		}
	}

	return stmts
}

// unlabel returns the inner statement for the possibly labeled statement stmt,
// stripping any (possibly nested) *ast.LabeledStmt wrapper.
//
// The second result reports whether stmt was an *ast.LabeledStmt.
func unlabel(stmt ast.Stmt) (ast.Stmt, bool) {
	labeled := false
	for {
		labelStmt, ok := stmt.(*ast.LabeledStmt)
		if !ok {
			return stmt, labeled
		}
		labeled = true
		stmt = labelStmt.Stmt
	}
}

func isMethodCall(info *types.Info, call *ast.CallExpr, pkgPath, typeName, method string) bool {
	return typesinternal.IsMethodNamed(typeutil.Callee(info, call), pkgPath, typeName, method)
}


================================================
FILE: go/analysis/passes/loopclosure/loopclosure_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package loopclosure_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/loopclosure"
	"golang.org/x/tools/internal/testfiles"
)

func TestVersions(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "src", "versions", "go22.txtar"))
	analysistest.Run(t, dir, loopclosure.Analyzer, "golang.org/fake/versions")
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/a/a.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains legacy tests for the loopclosure checker.
// Legacy expectations are incorrect after go1.22.

package testdata

import (
	"sync"

	"golang.org/x/sync/errgroup"
)

var A int

func _() {
	var s []int
	for i, v := range s {
		go func() {
			println(i) // want "loop variable i captured by func literal"
			println(v) // want "loop variable v captured by func literal"
		}()
	}
	for i, v := range s {
		defer func() {
			println(i) // want "loop variable i captured by func literal"
			println(v) // want "loop variable v captured by func literal"
		}()
	}
	for i := range s {
		go func() {
			println(i) // want "loop variable i captured by func literal"
		}()
	}
	for _, v := range s {
		go func() {
			println(v) // want "loop variable v captured by func literal"
		}()
	}
	for i, v := range s {
		go func() {
			println(i, v)
		}()
		println("unfortunately, we don't catch the error above because of this statement")
	}
	for i, v := range s {
		go func(i, v int) {
			println(i, v)
		}(i, v)
	}
	for i, v := range s {
		i, v := i, v
		go func() {
			println(i, v)
		}()
	}

	// iteration variable declared outside the loop
	for A = range s {
		go func() {
			println(A) // want "loop variable A captured by func literal"
		}()
	}
	// iteration variable declared in a different file
	for B = range s {
		go func() {
			println(B) // want "loop variable B captured by func literal"
		}()
	}
	// If the key of the range statement is not an identifier
	// the code should not panic (it used to).
	var x [2]int
	var f int
	for x[0], f = range s {
		go func() {
			_ = f // want "loop variable f captured by func literal"
		}()
	}
	type T struct {
		v int
	}
	for _, v := range s {
		go func() {
			_ = T{v: 1}
			_ = map[int]int{v: 1} // want "loop variable v captured by func literal"
		}()
	}

	// ordinary for-loops
	for i := 0; i < 10; i++ {
		go func() {
			print(i) // want "loop variable i captured by func literal"
		}()
	}
	for i, j := 0, 1; i < 100; i, j = j, i+j {
		go func() {
			print(j) // want "loop variable j captured by func literal"
		}()
	}
	type cons struct {
		car int
		cdr *cons
	}
	var head *cons
	for p := head; p != nil; p = p.cdr {
		go func() {
			print(p.car) // want "loop variable p captured by func literal"
		}()
	}
}

// Cases that rely on recursively checking for last statements.
func _() {

	for i := range "outer" {
		for j := range "inner" {
			if j < 1 {
				defer func() {
					print(i) // want "loop variable i captured by func literal"
				}()
			} else if j < 2 {
				go func() {
					print(i) // want "loop variable i captured by func literal"
				}()
			} else {
				go func() {
					print(i)
				}()
				println("we don't catch the error above because of this statement")
			}
		}
	}

	for i := 0; i < 10; i++ {
		for j := 0; j < 10; j++ {
			if j < 1 {
				switch j {
				case 0:
					defer func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				default:
					go func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				}
			} else if j < 2 {
				var a interface{} = j
				switch a.(type) {
				case int:
					defer func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				default:
					go func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				}
			} else {
				ch := make(chan string)
				select {
				case <-ch:
					defer func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				default:
					go func() {
						print(i) // want "loop variable i captured by func literal"
					}()
				}
			}
		}
	}
}

// Group is used to test that loopclosure only matches Group.Go when Group is
// from the golang.org/x/sync/errgroup package.
type Group struct{}

func (g *Group) Go(func() error) {}

func _() {
	var s []int
	// errgroup.Group.Go() invokes Go routines
	g := new(errgroup.Group)
	for i, v := range s {
		g.Go(func() error {
			print(i) // want "loop variable i captured by func literal"
			print(v) // want "loop variable v captured by func literal"
			return nil
		})
	}

	for i, v := range s {
		if i > 0 {
			g.Go(func() error {
				print(i) // want "loop variable i captured by func literal"
				return nil
			})
		} else {
			g.Go(func() error {
				print(v) // want "loop variable v captured by func literal"
				return nil
			})
		}
	}

	// Do not match other Group.Go cases
	g1 := new(Group)
	for i, v := range s {
		g1.Go(func() error {
			print(i)
			print(v)
			return nil
		})
	}
}

// Real-world example from #16520, slightly simplified
func _() {
	var nodes []interface{}

	critical := new(errgroup.Group)
	others := sync.WaitGroup{}

	isCritical := func(node interface{}) bool { return false }
	run := func(node interface{}) error { return nil }

	for _, node := range nodes {
		if isCritical(node) {
			critical.Go(func() error {
				return run(node) // want "loop variable node captured by func literal"
			})
		} else {
			others.Add(1)
			go func() {
				_ = run(node) // want "loop variable node captured by func literal"
				others.Done()
			}()
		}
	}
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/a/b.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

// B is declared in a separate file to test that object resolution spans the
// entire package.
var B int


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/golang.org/x/sync/errgroup/errgroup.go
================================================
// Package errgroup synthesizes Go's package "golang.org/x/sync/errgroup",
// which is used in unit-testing.
package errgroup

type Group struct {
}

func (g *Group) Go(f func() error) {
	go func() {
		f()
	}()
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/subtests/subtest.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains legacy tests that the loopclosure analyzer detects leaked
// references via parallel subtests.
// Legacy expectations are incorrect after go1.22.

package subtests

import (
	"testing"
)

// T is used to test that loopclosure only matches T.Run when T is from the
// testing package.
type T struct{}

// Run should not match testing.T.Run. Note that the second argument is
// intentionally a *testing.T, not a *T, so that we can check both
// testing.T.Parallel inside a T.Run, and a T.Parallel inside a testing.T.Run.
func (t *T) Run(string, func(*testing.T)) {
}

func (t *T) Parallel() {}

func _(t *testing.T) {
	for i, test := range []int{1, 2, 3} {
		// Check that parallel subtests are identified.
		t.Run("", func(t *testing.T) {
			t.Parallel()
			println(i)    // want "loop variable i captured by func literal"
			println(test) // want "loop variable test captured by func literal"
		})

		// Check that serial tests are OK.
		t.Run("", func(t *testing.T) {
			println(i)
			println(test)
		})

		// Check that the location of t.Parallel matters.
		t.Run("", func(t *testing.T) {
			println(i)
			println(test)
			t.Parallel()
			println(i)    // want "loop variable i captured by func literal"
			println(test) // want "loop variable test captured by func literal"
		})

		// Check that *testing.T value matters.
		t.Run("", func(t *testing.T) {
			var x testing.T
			x.Parallel()
			println(i)
			println(test)
		})

		// Check that shadowing the loop variables within the test literal is OK if
		// it occurs before t.Parallel().
		t.Run("", func(t *testing.T) {
			i := i
			test := test
			t.Parallel()
			println(i)
			println(test)
		})

		// Check that shadowing the loop variables within the test literal is Not
		// OK if it occurs after t.Parallel().
		t.Run("", func(t *testing.T) {
			t.Parallel()
			i := i        // want "loop variable i captured by func literal"
			test := test  // want "loop variable test captured by func literal"
			println(i)    // OK
			println(test) // OK
		})

		// Check uses in nested blocks.
		t.Run("", func(t *testing.T) {
			t.Parallel()
			{
				println(i)    // want "loop variable i captured by func literal"
				println(test) // want "loop variable test captured by func literal"
			}
		})

		// Check that we catch uses in nested subtests.
		t.Run("", func(t *testing.T) {
			t.Parallel()
			t.Run("", func(t *testing.T) {
				println(i)    // want "loop variable i captured by func literal"
				println(test) // want "loop variable test captured by func literal"
			})
		})

		// Check that there is no diagnostic if t is not a *testing.T.
		t.Run("", func(_ *testing.T) {
			t := &T{}
			t.Parallel()
			println(i)
			println(test)
		})

		// Check that there is no diagnostic when a jump to a label may have caused
		// the call to t.Parallel to have been skipped.
		t.Run("", func(t *testing.T) {
			if true {
				goto Test
			}
			t.Parallel()
		Test:
			println(i)
			println(test)
		})

		// Check that there is no diagnostic when a jump to a label may have caused
		// the loop variable reference to be skipped, but there is a diagnostic
		// when both the call to t.Parallel and the loop variable reference occur
		// after the final label in the block.
		t.Run("", func(t *testing.T) {
			if true {
				goto Test
			}
			t.Parallel()
			println(i) // maybe OK
		Test:
			t.Parallel()
			println(test) // want "loop variable test captured by func literal"
		})

		// Check that multiple labels are handled.
		t.Run("", func(t *testing.T) {
			if true {
				goto Test1
			} else {
				goto Test2
			}
		Test1:
		Test2:
			t.Parallel()
			println(test) // want "loop variable test captured by func literal"
		})

		// Check that we do not have problems when t.Run has a single argument.
		fn := func() (string, func(t *testing.T)) { return "", nil }
		t.Run(fn())
	}
}

// Check that there is no diagnostic when loop variables are shadowed within
// the loop body.
func _(t *testing.T) {
	for i, test := range []int{1, 2, 3} {
		i := i
		test := test
		t.Run("", func(t *testing.T) {
			t.Parallel()
			println(i)
			println(test)
		})
	}
}

// Check that t.Run must be *testing.T.Run.
func _(t *T) {
	for i, test := range []int{1, 2, 3} {
		t.Run("", func(t *testing.T) {
			t.Parallel()
			println(i)
			println(test)
		})
	}
}

// Check that the top-level must be parallel in order to cause a diagnostic.
//
// From https://pkg.go.dev/testing:
//
//	"Run does not return until parallel subtests have completed, providing a
//	way to clean up after a group of parallel tests"
func _(t *testing.T) {
	for _, test := range []int{1, 2, 3} {
		// In this subtest, a/b must complete before the synchronous subtest "a"
		// completes, so the reference to test does not escape the current loop
		// iteration.
		t.Run("a", func(s *testing.T) {
			s.Run("b", func(u *testing.T) {
				u.Parallel()
				println(test)
			})
		})

		// In this subtest, c executes concurrently, so the reference to test may
		// escape the current loop iteration.
		t.Run("c", func(s *testing.T) {
			s.Parallel()
			s.Run("d", func(u *testing.T) {
				println(test) // want "loop variable test captured by func literal"
			})
		})
	}
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains legacy tests for the loopclosure checker for GoVersion <go1.22.
// Expectations are incorrect after go1.22.

//go:build go1.19

package typeparams

import "golang.org/x/sync/errgroup"

func f[T any](data T) {
	print(data)
}

func _[T any]() {
	var s []T
	for i, v := range s {
		go func() {
			f(i) // want "loop variable i captured by func literal"
			f(v) // want "loop variable v captured by func literal"
		}()
	}
}

func loop[P interface{ Go(func() error) }](grp P) {
	var s []int
	for i, v := range s {
		// The checker only matches on methods "(*...errgroup.Group).Go".
		grp.Go(func() error {
			print(i)
			print(v)
			return nil
		})
	}
}

func _() {
	g := new(errgroup.Group)
	loop(g) // the analyzer is not "type inter-procedural" so no findings are reported
}

type T[P any] struct {
	a P
}

func (t T[P]) Go(func() error) {}

func _(g T[errgroup.Group]) {
	var s []int
	for i, v := range s {
		// "T.a" is method "(*...errgroup.Group).Go".
		g.a.Go(func() error {
			print(i) // want "loop variable i captured by func literal"
			print(v) // want "loop variable v captured by func literal"
			return nil
		})
	}
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/versions/go18.txtar
================================================
Test loopclosure at go version go1.19.

-- go.mod --
module golang.org/fake/versions

go 1.19
-- pre.go --
//go:build go1.19

package versions

func InGo18(l []int) {
  for i, v := range l {
    go func() {
      print(i) // want "loop variable i captured by func literal"
      print(v) // want "loop variable v captured by func literal"
    }()
  }
}
-- go22.go --
//go:build go1.22

package versions

func InGo22(l []int) {
	for i, v := range l {
		go func() {
			print(i) // Not reported due to file's GoVersion.
			print(v) // Not reported due to file's GoVersion.
		}()
	}
}
-- modver.go --
package versions

func At18FromModuleVersion(l []int) {
	for i, v := range l {
		go func() {
			print(i) // want "loop variable i captured by func literal"
			print(v) // want "loop variable v captured by func literal"
		}()
	}
}


================================================
FILE: go/analysis/passes/loopclosure/testdata/src/versions/go22.txtar
================================================
Test loopclosure at go version go1.22.

The go1.21 build tag is necessary to force the file version.

-- go.mod --
module golang.org/fake/versions

go 1.22
-- pre.go --
//go:build go1.21

package versions

func Bad(l []int) {
  for i, v := range l {
    go func() {
      print(i) // want "loop variable i captured by func literal"
      print(v) // want "loop variable v captured by func literal"
    }()
  }
}
-- go22.go --
//go:build go1.22

package versions

func InGo22(l []int) {
	for i, v := range l {
		go func() {
			print(i) // Not reported due to file's GoVersion.
			print(v) // Not reported due to file's GoVersion.
		}()
	}
}

-- modver.go --
package versions

func At22FromTheModuleVersion(l []int) {
	for i, v := range l {
		go func() {
			print(i) // Not reported due to module's GoVersion.
			print(v) // Not reported due to module's GoVersion.
		}()
	}
}


================================================
FILE: go/analysis/passes/lostcancel/cmd/lostcancel/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The lostcancel command applies the golang.org/x/tools/go/analysis/passes/lostcancel
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/lostcancel"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(lostcancel.Analyzer) }


================================================
FILE: go/analysis/passes/lostcancel/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package lostcancel defines an Analyzer that checks for failure to
// call a context cancellation function.
//
// # Analyzer lostcancel
//
// lostcancel: check cancel func returned by context.WithCancel is called
//
// The cancellation function returned by context.WithCancel, WithTimeout,
// WithDeadline and variants such as WithCancelCause must be called,
// or the new context will remain live until its parent context is cancelled.
// (The background context is never cancelled.)
package lostcancel


================================================
FILE: go/analysis/passes/lostcancel/lostcancel.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lostcancel

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/ctrlflow"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/cfg"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name: "lostcancel",
	Doc:  analyzerutil.MustExtractDoc(doc, "lostcancel"),
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/lostcancel",
	Run:  run,
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		ctrlflow.Analyzer,
	},
}

const debug = false

var contextPackage = "context"

// checkLostCancel reports a failure to the call the cancel function
// returned by context.WithCancel, either because the variable was
// assigned to the blank identifier, or because there exists a
// control-flow path from the call to a return statement and that path
// does not "use" the cancel function.  Any reference to the variable
// counts as a use, even within a nested function literal.
// If the variable's scope is larger than the function
// containing the assignment, we assume that other uses exist.
//
// checkLostCancel analyzes a single named or literal function.
func run(pass *analysis.Pass) (any, error) {
	// Fast path: bypass check if file doesn't use context.WithCancel.
	if !typesinternal.Imports(pass.Pkg, contextPackage) {
		return nil, nil
	}

	// Call runFunc for each Func{Decl,Lit}.
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeTypes := []ast.Node{
		(*ast.FuncLit)(nil),
		(*ast.FuncDecl)(nil),
	}
	inspect.Preorder(nodeTypes, func(n ast.Node) {
		runFunc(pass, n)
	})
	return nil, nil
}

func runFunc(pass *analysis.Pass, node ast.Node) {
	// Find scope of function node
	var funcScope *types.Scope
	switch v := node.(type) {
	case *ast.FuncLit:
		funcScope = pass.TypesInfo.Scopes[v.Type]
	case *ast.FuncDecl:
		funcScope = pass.TypesInfo.Scopes[v.Type]
	}

	// Maps each cancel variable to its defining ValueSpec/AssignStmt.
	cancelvars := make(map[*types.Var]ast.Node)

	// TODO(adonovan): opt: refactor to make a single pass
	// over the AST using inspect.WithStack and node types
	// {FuncDecl,FuncLit,CallExpr,SelectorExpr}.

	// Find the set of cancel vars to analyze.
	ast.PreorderStack(node, nil, func(n ast.Node, stack []ast.Node) bool {
		if _, ok := n.(*ast.FuncLit); ok && len(stack) > 0 {
			return false // don't stray into nested functions
		}

		// Look for n=SelectorExpr beneath stack=[{AssignStmt,ValueSpec} CallExpr]:
		//
		//   ctx, cancel    := context.WithCancel(...)
		//   ctx, cancel     = context.WithCancel(...)
		//   var ctx, cancel = context.WithCancel(...)
		//
		if !isContextWithCancel(pass.TypesInfo, n) || !isCall(stack[len(stack)-1]) {
			return true
		}
		var id *ast.Ident // id of cancel var
		stmt := stack[len(stack)-2]
		switch stmt := stmt.(type) {
		case *ast.ValueSpec:
			if len(stmt.Names) > 1 {
				id = stmt.Names[1]
			}
		case *ast.AssignStmt:
			if len(stmt.Lhs) > 1 {
				id, _ = stmt.Lhs[1].(*ast.Ident)
			}
		}
		if id != nil {
			if id.Name == "_" {
				pass.ReportRangef(id,
					"the cancel function returned by context.%s should be called, not discarded, to avoid a context leak",
					n.(*ast.SelectorExpr).Sel.Name)
			} else if v, ok := pass.TypesInfo.Uses[id].(*types.Var); ok {
				// If the cancel variable is defined outside function scope,
				// do not analyze it.
				if funcScope.Contains(v.Pos()) {
					cancelvars[v] = stmt
				}
			} else if v, ok := pass.TypesInfo.Defs[id].(*types.Var); ok {
				cancelvars[v] = stmt
			}
		}
		return true
	})

	if len(cancelvars) == 0 {
		return // no need to inspect CFG
	}

	// Obtain the CFG.
	cfgs := pass.ResultOf[ctrlflow.Analyzer].(*ctrlflow.CFGs)
	var g *cfg.CFG
	var sig *types.Signature
	switch node := node.(type) {
	case *ast.FuncDecl:
		sig, _ = pass.TypesInfo.Defs[node.Name].Type().(*types.Signature)
		if node.Name.Name == "main" && sig.Recv() == nil && pass.Pkg.Name() == "main" {
			// Returning from main.main terminates the process,
			// so there's no need to cancel contexts.
			return
		}
		g = cfgs.FuncDecl(node)

	case *ast.FuncLit:
		sig, _ = pass.TypesInfo.Types[node.Type].Type.(*types.Signature)
		g = cfgs.FuncLit(node)
	}
	if sig == nil {
		return // missing type information
	}

	// Print CFG.
	if debug {
		fmt.Println(g.Format(pass.Fset))
	}

	// Examine the CFG for each variable in turn.
	// (It would be more efficient to analyze all cancelvars in a
	// single pass over the AST, but seldom is there more than one.)
	for v, stmt := range cancelvars {
		if ret := lostCancelPath(pass, g, v, stmt, sig); ret != nil {
			lineno := pass.Fset.Position(stmt.Pos()).Line
			pass.ReportRangef(stmt, "the %s function is not used on all paths (possible context leak)", v.Name())

			pos, end := ret.Pos(), ret.End()
			// golang/go#64547: cfg.Block.Return may return a synthetic
			// ReturnStmt that overflows the file.
			if pass.Fset.File(pos) != pass.Fset.File(end) {
				end = pos
			}
			pass.Report(analysis.Diagnostic{
				Pos:     pos,
				End:     end,
				Message: fmt.Sprintf("this return statement may be reached without using the %s var defined on line %d", v.Name(), lineno),
			})
		}
	}
}

func isCall(n ast.Node) bool { _, ok := n.(*ast.CallExpr); return ok }

// isContextWithCancel reports whether n is one of the qualified identifiers
// context.With{Cancel,Timeout,Deadline}.
func isContextWithCancel(info *types.Info, n ast.Node) bool {
	sel, ok := n.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	switch sel.Sel.Name {
	case "WithCancel", "WithCancelCause",
		"WithTimeout", "WithTimeoutCause",
		"WithDeadline", "WithDeadlineCause":
	default:
		return false
	}
	if x, ok := sel.X.(*ast.Ident); ok {
		if pkgname, ok := info.Uses[x].(*types.PkgName); ok {
			return pkgname.Imported().Path() == contextPackage
		}
		// Import failed, so we can't check package path.
		// Just check the local package name (heuristic).
		return x.Name == "context"
	}
	return false
}

// lostCancelPath finds a path through the CFG, from stmt (which defines
// the 'cancel' variable v) to a return statement, that doesn't "use" v.
// If it finds one, it returns the return statement (which may be synthetic).
// sig is the function's type, if known.
func lostCancelPath(pass *analysis.Pass, g *cfg.CFG, v *types.Var, stmt ast.Node, sig *types.Signature) *ast.ReturnStmt {
	vIsNamedResult := sig != nil && tupleContains(sig.Results(), v)

	// uses reports whether stmts contain a "use" of variable v.
	uses := func(pass *analysis.Pass, v *types.Var, stmts []ast.Node) bool {
		found := false
		for _, stmt := range stmts {
			ast.Inspect(stmt, func(n ast.Node) bool {
				switch n := n.(type) {
				case *ast.Ident:
					if pass.TypesInfo.Uses[n] == v {
						found = true
					}
				case *ast.ReturnStmt:
					// A naked return statement counts as a use
					// of the named result variables.
					if n.Results == nil && vIsNamedResult {
						found = true
					}
				}
				return !found
			})
		}
		return found
	}

	// blockUses computes "uses" for each block, caching the result.
	memo := make(map[*cfg.Block]bool)
	blockUses := func(pass *analysis.Pass, v *types.Var, b *cfg.Block) bool {
		res, ok := memo[b]
		if !ok {
			res = uses(pass, v, b.Nodes)
			memo[b] = res
		}
		return res
	}

	// Find the var's defining block in the CFG,
	// plus the rest of the statements of that block.
	var defblock *cfg.Block
	var rest []ast.Node
outer:
	for _, b := range g.Blocks {
		for i, n := range b.Nodes {
			if n == stmt {
				defblock = b
				rest = b.Nodes[i+1:]
				break outer
			}
		}
	}
	if defblock == nil {
		panic("internal error: can't find defining block for cancel var")
	}

	// Is v "used" in the remainder of its defining block?
	if uses(pass, v, rest) {
		return nil
	}

	// Does the defining block return without using v?
	if ret := defblock.Return(); ret != nil {
		return ret
	}

	// Search the CFG depth-first for a path, from defblock to a
	// return block, in which v is never "used".
	seen := make(map[*cfg.Block]bool)
	var search func(blocks []*cfg.Block) *ast.ReturnStmt
	search = func(blocks []*cfg.Block) *ast.ReturnStmt {
		for _, b := range blocks {
			if seen[b] {
				continue
			}
			seen[b] = true

			// Prune the search if the block uses v.
			if blockUses(pass, v, b) {
				continue
			}

			// Found path to return statement?
			if ret := b.Return(); ret != nil {
				if debug {
					fmt.Printf("found path to return in block %s\n", b)
				}
				return ret // found
			}

			// Recur
			if ret := search(b.Succs); ret != nil {
				if debug {
					fmt.Printf(" from block %s\n", b)
				}
				return ret
			}
		}
		return nil
	}
	return search(defblock.Succs)
}

func tupleContains(tuple *types.Tuple, v *types.Var) bool {
	for v0 := range tuple.Variables() {
		if v0 == v {
			return true
		}
	}
	return false
}


================================================
FILE: go/analysis/passes/lostcancel/lostcancel_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lostcancel_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/lostcancel"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, lostcancel.Analyzer, "a", "b", "typeparams")
}


================================================
FILE: go/analysis/passes/lostcancel/testdata/src/a/a.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"context"
	"log"
	"os"
	"testing"
	"time"
)

var bg = context.Background()

// Check the three functions and assignment forms (var, :=, =) we look for.
// (Do these early: line numbers are fragile.)
func _() {
	var _, cancel = context.WithCancel(bg) // want `the cancel function is not used on all paths \(possible context leak\)`
	if false {
		_ = cancel
	}
} // want "this return statement may be reached without using the cancel var defined on line 20"

func _() {
	_, cancel2 := context.WithDeadline(bg, time.Time{}) // want "the cancel2 function is not used..."
	if false {
		_ = cancel2
	}
} // want "may be reached without using the cancel2 var defined on line 27"

func _() {
	var cancel3 func()
	_, cancel3 = context.WithTimeout(bg, 0) // want "function is not used..."
	if false {
		_ = cancel3
	}
} // want "this return statement may be reached without using the cancel3 var defined on line 35"

func _() {
	ctx, _ := context.WithCancel(bg)               // want "the cancel function returned by context.WithCancel should be called, not discarded, to avoid a context leak"
	ctx, _ = context.WithTimeout(bg, 0)            // want "the cancel function returned by context.WithTimeout should be called, not discarded, to avoid a context leak"
	ctx, _ = context.WithDeadline(bg, time.Time{}) // want "the cancel function returned by context.WithDeadline should be called, not discarded, to avoid a context leak"
	_ = ctx
}

func _() {
	_, cancel := context.WithCancel(bg)
	defer cancel() // ok
}

func _() {
	_, cancel := context.WithCancel(bg) // want "not used on all paths"
	if condition {
		cancel()
	}
	return // want "this return statement may be reached without using the cancel var"
}

func _() {
	_, cancel := context.WithCancel(bg)
	if condition {
		cancel()
	} else {
		// ok: infinite loop
		for {
			print(0)
		}
	}
}

func _() {
	_, cancel := context.WithCancel(bg) // want "not used on all paths"
	if condition {
		cancel()
	} else {
		for i := 0; i < 10; i++ {
			print(0)
		}
	}
} // want "this return statement may be reached without using the cancel var"

func _() {
	_, cancel := context.WithCancel(bg)
	// ok: used on all paths
	switch someInt {
	case 0:
		new(testing.T).FailNow()
	case 1:
		log.Fatal()
	case 2:
		cancel()
	case 3:
		print("hi")
		fallthrough
	default:
		os.Exit(1)
	}
}

func _() {
	_, cancel := context.WithCancel(bg) // want "not used on all paths"
	switch someInt {
	case 0:
		new(testing.T).FailNow()
	case 1:
		log.Fatal()
	case 2:
		cancel()
	case 3:
		print("hi") // falls through to implicit return
	default:
		os.Exit(1)
	}
} // want "this return statement may be reached without using the cancel var"

func _(ch chan int) {
	_, cancel := context.WithCancel(bg) // want "not used on all paths"
	select {
	case <-ch:
		new(testing.T).FailNow()
	case ch <- 2:
		print("hi") // falls through to implicit return
	case ch <- 1:
		cancel()
	default:
		os.Exit(1)
	}
} // want "this return statement may be reached without using the cancel var"

func _(ch chan int) {
	_, cancel := context.WithCancel(bg)
	// A blocking select must execute one of its cases.
	select {
	case <-ch:
		panic(0)
	}
	if false {
		_ = cancel
	}
}

func _() {
	go func() {
		ctx, cancel := context.WithCancel(bg) // want "not used on all paths"
		if false {
			_ = cancel
		}
		print(ctx)
	}() // want "may be reached without using the cancel var"
}

var condition bool
var someInt int

// Regression test for Go issue 16143.
func _() {
	var x struct{ f func() }
	x.f()
}

// Regression test for Go issue 16230.
func _() (ctx context.Context, cancel func()) {
	ctx, cancel = context.WithCancel(bg)
	return // a naked return counts as a load of the named result values
}

// Same as above, but for literal function.
var _ = func() (ctx context.Context, cancel func()) {
	ctx, cancel = context.WithCancel(bg)
	return
}

// Test for Go issue 31856.
func _() {
	var cancel func()

	func() {
		_, cancel = context.WithCancel(bg)
	}()

	cancel()
}

var cancel1 func()

// Same as above, but for package-level cancel variable.
func _() {
	// We assume that other uses of cancel1 exist.
	_, cancel1 = context.WithCancel(bg)
}


================================================
FILE: go/analysis/passes/lostcancel/testdata/src/b/b.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import "context"

// Return from main is handled specially.
// Since the program exits, there's no need to call cancel.
func main() {
	_, cancel := context.WithCancel(nil)
	if maybe {
		cancel()
	}
}

func notMain() {
	_, cancel := context.WithCancel(nil) // want "cancel function.*not used"

	if maybe {
		cancel()
	}
} // want "return statement.*reached without using the cancel"

var maybe bool


================================================
FILE: go/analysis/passes/lostcancel/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the lostcancel checker.

package typeparams

import (
	"context"
	"io"
	"time"
)

//
// These comment lines are ballast to ensure
// that this is L17. Add/remove as needed.

var bg = context.Background()

func _[T any]() {
	var _, cancel = context.WithCancel(bg) // want `the cancel function is not used on all paths \(possible context leak\)`
	if false {
		_ = cancel
	}
} // want "this return statement may be reached without using the cancel var defined on line 22"

func _[T any]() {
	_, cancel := context.WithCancel(bg)
	defer cancel() // ok
}

// User-defined Context that matches type "context.Context"
type C1[P1 any, P2 any] interface {
	Deadline() (deadline time.Time, ok P1)
	Done() <-chan struct{}
	Err() error
	Value(key P2) P2
}

func _(bg C1[bool, interface{}]) {
	ctx, _ := context.WithCancel(bg)    // want "the cancel function returned by context.WithCancel should be called, not discarded, to avoid a context leak"
	ctx, _ = context.WithTimeout(bg, 0) // want "the cancel function returned by context.WithTimeout should be called, not discarded, to avoid a context leak"
	_ = ctx
}

// User-defined Context that doesn't match type "context.Context"
type C2[P any] interface {
	WithCancel(parent C1[P, bool]) (ctx C1[P, bool], cancel func())
}

func _(c C2[interface{}]) {
	ctx, _ := c.WithCancel(nil) // not "context.WithCancel()"
	_ = ctx
}

// Further regression test for Go issue 16143.
func _() {
	type C[P any] struct{ f func() P }
	var x C[int]
	x.f()
}

func withCancelCause(maybe bool) {
	{
		_, cancel := context.WithCancelCause(bg)
		defer cancel(io.EOF) // ok
	}
	{
		_, cancel := context.WithCancelCause(bg) // want "the cancel function is not used on all paths \\(possible context leak\\)"
		if maybe {
			cancel(io.EOF)
		}
	}
} // want "this return statement may be reached without using the cancel var defined on line 70"


================================================
FILE: go/analysis/passes/modernize/any.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/versions"
)

var AnyAnalyzer = &analysis.Analyzer{
	Name:     "any",
	Doc:      analyzerutil.MustExtractDoc(doc, "any"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      runAny,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#any",
}

// The any pass replaces interface{} with go1.18's 'any'.
func runAny(pass *analysis.Pass) (any, error) {
	for curFile := range filesUsingGoVersion(pass, versions.Go1_18) {
		for curIface := range curFile.Preorder((*ast.InterfaceType)(nil)) {
			iface := curIface.Node().(*ast.InterfaceType)

			if iface.Methods.NumFields() == 0 {
				// Check that 'any' is not shadowed.
				if lookup(pass.TypesInfo, curIface, "any") == builtinAny {
					pass.Report(analysis.Diagnostic{
						Pos:     iface.Pos(),
						End:     iface.End(),
						Message: "interface{} can be replaced by any",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Replace interface{} by any",
							TextEdits: []analysis.TextEdit{
								{
									Pos:     iface.Pos(),
									End:     iface.End(),
									NewText: []byte("any"),
								},
							},
						}},
					})
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/atomictypes.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var atomicTypesAnalyzer = &analysis.Analyzer{
	Name: "atomictypes",
	Doc:  analyzerutil.MustExtractDoc(doc, "atomictypes"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: runAtomic,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#atomictypes",
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.AtomicTypesModernizer = atomicTypesAnalyzer
}

// TODO(mkalil): support the Pointer variants.
// Consider the following function signatures for pointer loading:
// func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
// func (x *Pointer[T]) Load() *T
// Since the former uses *unsafe.Pointer while the latter uses *Pointer[T],
// we would need to determine the type T to apply the transformation, and there
// will be additional edits required to remove any *unsafe.Pointer casts.
// 	"LoadPointer", "StorePointer", "SwapPointer", "CompareAndSwapPointer"

// sync/atomic functions of interest. Some added in go1.19, some added in go1.23.
var syncAtomicFuncs = []string{
	// Added in go1.19.
	"AddInt32", "AddInt64", "AddUint32", "AddUint64", "AddUintptr",
	"CompareAndSwapInt32", "CompareAndSwapInt64", "CompareAndSwapUint32", "CompareAndSwapUint64", "CompareAndSwapUintptr",
	"LoadInt32", "LoadInt64", "LoadUint32", "LoadUint64", "LoadUintptr",
	"StoreInt32", "StoreInt64", "StoreUint32", "StoreUint64", "StoreUintptr",
	"SwapInt32", "SwapInt64", "SwapUint32", "SwapUint64", "SwapUintptr",
	// Added in go1.23.
	"AndInt32", "AndInt64", "AndUint32", "AndUint64", "AndUintptr",
	"OrInt32", "OrInt64", "OrUint32", "OrUint64", "OrUintptr",
}

func runAtomic(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "sync/atomic") {
		return nil, nil // doesn't directly import sync/atomic
	}

	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	// Gather all candidate variables v appearing
	// in calls to atomic.AddInt32(&v, ...) et al.
	var (
		atomicPkg *types.Package
		vars      = make(map[*types.Var]string) // maps candidate vars v to the name of the call they appear in
	)
	for _, funcName := range syncAtomicFuncs {
		obj := index.Object("sync/atomic", funcName)
		if obj == nil {
			continue
		}
		atomicPkg = obj.Pkg()
		for curCall := range index.Calls(obj) {
			call := curCall.Node().(*ast.CallExpr)
			if unary, ok := call.Args[0].(*ast.UnaryExpr); ok && unary.Op == token.AND {
				var v *types.Var
				switch x := unary.X.(type) {
				case *ast.Ident:
					v, _ = info.Uses[x].(*types.Var)
				case *ast.SelectorExpr:
					if seln, ok := info.Selections[x]; ok {
						v, _ = seln.Obj().(*types.Var)
					}
				}
				if v != nil && !v.Exported() {
					// v must be a non-exported package or local var, or a struct field.
					switch v.Kind() {
					case types.RecvVar, types.ParamVar, types.ResultVar:
						continue // fix would change func signature
					}
					vars[v] = funcName
				}
			}
		}
	}

	// Check that all uses of each candidate variable
	// appear in calls of the form atomic.AddInt32(&v, ...).
nextvar:
	for v, funcName := range vars {
		var edits []analysis.TextEdit
		fixFiles := make(map[*ast.File]bool) // unique files involved in the current fix

		// Check the form of the declaration: var v int or struct { v int }
		def, ok := index.Def(v)
		if !ok {
			continue
		}
		var (
			typ   ast.Expr
			names []*ast.Ident
		)
		switch parent := def.Parent().Node().(type) {
		case *ast.Field: // struct { v int }
			names = parent.Names
			typ = parent.Type
		case *ast.ValueSpec: // var v int
			if len(parent.Values) > 0 {
				// e.g. var v int = 5
				// skip because rewriting as `var v atomic.Int32 = 5` is invalid
				continue
			}
			names = parent.Names
			typ = parent.Type
		}
		if len(names) != 1 || typ == nil {
			continue // v is not the sole var declared here (e.g. var x, y int32); or no explicit type
		}
		oldType := info.TypeOf(typ)                             // e.g. "int32"
		newType := strings.Title(oldType.Underlying().String()) // e.g. "Int32"

		// Get package prefix to avoid shadowing.
		file := astutil.EnclosingFile(def)
		pkgPrefix, impEdits := refactor.AddImport(pass.TypesInfo, file, "atomic", "sync/atomic", "", def.Node().Pos())
		if len(impEdits) > 0 {
			panic("unexpected import edits") // atomic PkgName should be in scope already
		}
		// Edit the type.
		//
		// var v int32
		//       ------------
		// var v atomic.Int32
		edits = append(edits, analysis.TextEdit{
			Pos:     typ.Pos(),
			End:     typ.End(),
			NewText: fmt.Appendf(nil, "%s%s", pkgPrefix, newType),
		})
		fixFiles[file] = true

		// Each valid use is an Ident v or Selector expr.v within an atomic.F(&...) call.
		var validUses []inspector.Cursor
		for cur := range index.Uses(v) {
			if v.IsField() && cur.ParentEdgeKind() == edge.KeyValueExpr_Key {
				continue nextvar // we cannot fix initial an value assignment T{v: 1}
			}
			if cur.ParentEdgeKind() == edge.SelectorExpr_Sel {
				cur = cur.Parent() // ascend from v to expr.v
			}
			// Inv: cur is the l-value expression denoting v.
			// v must appear beneath atomic.AddInt32(&v, ...) call.
			valid := false
			if cur.ParentEdgeKind() == edge.UnaryExpr_X &&
				cur.Parent().Node().(*ast.UnaryExpr).Op == token.AND {
				if ek, idx := cur.Parent().ParentEdge(); ek == edge.CallExpr_Args && idx == 0 {
					curCall := cur.Parent().Parent()
					call := curCall.Node().(*ast.CallExpr)
					if fn, ok := typeutil.Callee(info, call).(*types.Func); ok && fn.Pkg() == atomicPkg {
						valid = true
					}
				}
			}

			if !valid {
				// More complex case: reject candidate.
				//
				// For example, cur may be an unsynchronized load (e.g. v == 0). To
				// avoid a type conversion error, we'd have to rewrite this as
				// v.Load(). However, this is an invalid rewrite: if the program is
				// mixing atomic operations with unsynchronized reads, the author
				// might have accidentally introduced a data race and the suggested
				// fix could obscure the mistake. Or, if the usage is intentional,
				// rewriting may result in a behavior change.
				continue nextvar
			}
			validUses = append(validUses, cur)
		}

		for _, cur := range validUses {
			vexpr := cur.Node()
			call := cur.Parent().Parent().Node().(*ast.CallExpr)
			fn := typeutil.Callee(info, call).(*types.Func)
			// atomic.AddInt32(&v,    ...)
			// ----------------- -----
			//                  v.Add(...)
			after := vexpr.End() // LoadInt32(&v⁁)
			if len(call.Args) > 1 {
				after = call.Args[1].Pos() // AddInt32(&v, ⁁...)
			}
			verb := strings.TrimSuffix(fn.Name(), newType) // "AddInt32" => "Add"
			edits = append(edits, []analysis.TextEdit{
				{
					Pos: call.Pos(),
					End: vexpr.Pos(),
				},
				{
					Pos:     vexpr.End(),
					End:     after,
					NewText: fmt.Appendf(nil, ".%s(", verb),
				},
			}...)
			fixFiles[astutil.EnclosingFile(cur)] = true
		}

		// Check minimum Go version: go1.19, or 1.23 for the And/Or functions.
		if !(analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_19) ||
			analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_23) &&
				(strings.HasPrefix(funcName, "And") || strings.HasPrefix(funcName, "Or"))) {
			continue
		}

		// Skip if v is not local and the package has ignored files as it may be
		// an incomplete transformation.
		if !isLocal(v) && len(pass.IgnoredFiles) > 0 {
			continue
		}

		pass.Report(analysis.Diagnostic{
			Pos:     names[0].Pos(),
			End:     typ.End(),
			Message: fmt.Sprintf("var %s %s may be simplified using atomic.%s", v.Name(), oldType, newType),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   fmt.Sprintf("Replace %s by atomic.%s", oldType, newType),
				TextEdits: edits,
			}},
		})
	}

	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/bloop.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var BLoopAnalyzer = &analysis.Analyzer{
	Name: "bloop",
	Doc:  analyzerutil.MustExtractDoc(doc, "bloop"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: bloop,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#bloop",
}

// bloop updates benchmarks that use "for range b.N", replacing it
// with go1.24's b.Loop() and eliminating any preceding
// b.{Start,Stop,Reset}Timer calls.
//
// Variants:
//
//	for i := 0; i < b.N; i++ {}  =>   for b.Loop() {}
//	for range b.N {}
func bloop(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "testing") {
		return nil, nil
	}

	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	// edits computes the text edits for a matched for/range loop
	// at the specified cursor. b is the *testing.B value, and
	// (start, end) is the portion using b.N to delete.
	edits := func(curLoop inspector.Cursor, b ast.Expr, start, end token.Pos) (edits []analysis.TextEdit) {
		curFn, _ := enclosingFunc(curLoop)
		// Within the same function, delete all calls to
		// b.{Start,Stop,Timer} that precede the loop.
		filter := []ast.Node{(*ast.ExprStmt)(nil), (*ast.FuncLit)(nil)}
		curFn.Inspect(filter, func(cur inspector.Cursor) (descend bool) {
			node := cur.Node()
			if is[*ast.FuncLit](node) {
				return false // don't descend into FuncLits (e.g. sub-benchmarks)
			}
			stmt := node.(*ast.ExprStmt)
			if stmt.Pos() > start {
				return false // not preceding: stop
			}
			if call, ok := stmt.X.(*ast.CallExpr); ok {
				obj := typeutil.Callee(info, call)
				if typesinternal.IsMethodNamed(obj, "testing", "B", "StopTimer", "StartTimer", "ResetTimer") {
					// Delete call statement.
					// TODO(adonovan): delete following newline, or
					// up to start of next stmt? (May delete a comment.)
					edits = append(edits, analysis.TextEdit{
						Pos: stmt.Pos(),
						End: stmt.End(),
					})
				}
			}
			return true
		})

		// Replace ...b.N... with b.Loop().
		return append(edits, analysis.TextEdit{
			Pos:     start,
			End:     end,
			NewText: fmt.Appendf(nil, "%s.Loop()", astutil.Format(pass.Fset, b)),
		})
	}

	// Find all for/range statements.
	loops := []ast.Node{
		(*ast.ForStmt)(nil),
		(*ast.RangeStmt)(nil),
	}
	for curFile := range filesUsingGoVersion(pass, versions.Go1_24) {
		for curLoop := range curFile.Preorder(loops...) {
			switch n := curLoop.Node().(type) {
			case *ast.ForStmt:
				// for _; i < b.N; _ {}
				if cmp, ok := n.Cond.(*ast.BinaryExpr); ok && cmp.Op == token.LSS {
					if sel, ok := cmp.Y.(*ast.SelectorExpr); ok &&
						sel.Sel.Name == "N" &&
						typesinternal.IsPointerToNamed(info.TypeOf(sel.X), "testing", "B") && usesBenchmarkNOnce(curLoop, info) {

						delStart, delEnd := n.Cond.Pos(), n.Cond.End()

						// Eliminate variable i if no longer needed:
						//  for i := 0; i < b.N; i++ {
						//    ...no references to i...
						//  }
						body, _ := curLoop.LastChild()
						if v := isIncrementLoop(info, n); v != nil &&
							!uses(index, body, v) {
							delStart, delEnd = n.Init.Pos(), n.Post.End()
						}

						pass.Report(analysis.Diagnostic{
							// Highlight "i < b.N".
							Pos:     n.Cond.Pos(),
							End:     n.Cond.End(),
							Message: "b.N can be modernized using b.Loop()",
							SuggestedFixes: []analysis.SuggestedFix{{
								Message:   "Replace b.N with b.Loop()",
								TextEdits: edits(curLoop, sel.X, delStart, delEnd),
							}},
						})
					}
				}

			case *ast.RangeStmt:
				// for range b.N {} -> for b.Loop() {}
				//
				// TODO(adonovan): handle "for i := range b.N".
				if sel, ok := n.X.(*ast.SelectorExpr); ok &&
					n.Key == nil &&
					n.Value == nil &&
					sel.Sel.Name == "N" &&
					typesinternal.IsPointerToNamed(info.TypeOf(sel.X), "testing", "B") && usesBenchmarkNOnce(curLoop, info) {

					pass.Report(analysis.Diagnostic{
						// Highlight "range b.N".
						Pos:     n.Range,
						End:     n.X.End(),
						Message: "b.N can be modernized using b.Loop()",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message:   "Replace b.N with b.Loop()",
							TextEdits: edits(curLoop, sel.X, n.Range, n.X.End()),
						}},
					})
				}
			}
		}
	}
	return nil, nil
}

// uses reports whether the subtree cur contains a use of obj.
func uses(index *typeindex.Index, cur inspector.Cursor, obj types.Object) bool {
	for use := range index.Uses(obj) {
		if cur.Contains(use) {
			return true
		}
	}
	return false
}

// enclosingFunc returns the cursor for the innermost Func{Decl,Lit}
// that encloses c, if any.
func enclosingFunc(c inspector.Cursor) (inspector.Cursor, bool) {
	return moreiters.First(c.Enclosing((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)))
}

// usesBenchmarkNOnce reports whether a b.N loop should be modernized to b.Loop().
// Only modernize loops that are:
// 1. Directly in a benchmark function (not in nested functions)
//   - b.Loop() must be called in the same goroutine as the benchmark function
//   - Function literals are often used with goroutines (go func(){...})
//
// 2. The only b.N loop in that benchmark function
//   - b.Loop() can only be called once per benchmark execution
//   - Multiple calls result in "B.Loop called with timer stopped" error
//   - Multiple loops may have complex interdependencies that are hard to analyze
func usesBenchmarkNOnce(c inspector.Cursor, info *types.Info) bool {
	// Find the enclosing benchmark function
	curFunc, ok := enclosingFunc(c)
	if !ok {
		return false
	}

	// Check if this is actually a benchmark function
	fdecl, ok := curFunc.Node().(*ast.FuncDecl)
	if !ok {
		return false // not in a function; or, inside a FuncLit
	}
	if !isBenchmarkFunc(fdecl) {
		return false
	}

	// Count all b.N references in this benchmark function (including nested functions)
	bnRefCount := 0
	filter := []ast.Node{(*ast.SelectorExpr)(nil)}
	curFunc.Inspect(filter, func(cur inspector.Cursor) bool {
		sel := cur.Node().(*ast.SelectorExpr)
		if sel.Sel.Name == "N" &&
			typesinternal.IsPointerToNamed(info.TypeOf(sel.X), "testing", "B") {
			bnRefCount++
		}
		return true
	})

	// Only modernize if there's exactly one b.N reference
	return bnRefCount == 1
}

// isBenchmarkFunc reports whether f is a benchmark function.
func isBenchmarkFunc(f *ast.FuncDecl) bool {
	return f.Recv == nil &&
		f.Name != nil &&
		f.Name.IsExported() &&
		strings.HasPrefix(f.Name.Name, "Benchmark") &&
		f.Type.Params != nil &&
		len(f.Type.Params.List) == 1
}

// isIncrementLoop reports whether loop has the form "for i := 0; ...; i++ { ... }",
// and if so, it returns the symbol for the index variable.
func isIncrementLoop(info *types.Info, loop *ast.ForStmt) *types.Var {
	if assign, ok := loop.Init.(*ast.AssignStmt); ok &&
		assign.Tok == token.DEFINE &&
		len(assign.Rhs) == 1 &&
		isZeroIntConst(info, assign.Rhs[0]) &&
		is[*ast.IncDecStmt](loop.Post) &&
		loop.Post.(*ast.IncDecStmt).Tok == token.INC &&
		astutil.EqualSyntax(loop.Post.(*ast.IncDecStmt).X, assign.Lhs[0]) {
		return info.Defs[assign.Lhs[0].(*ast.Ident)].(*types.Var)
	}
	return nil
}


================================================
FILE: go/analysis/passes/modernize/cmd/modernize/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The modernize command suggests (or, with -fix, applies) fixes that
// clarify Go code by using more modern features.
//
// See [golang.org/x/tools/go/analysis/passes/modernize] for details.
package main

import (
	"golang.org/x/tools/go/analysis/multichecker"
	"golang.org/x/tools/go/analysis/passes/modernize"
)

func main() { multichecker.Main(modernize.Suite...) }


================================================
FILE: go/analysis/passes/modernize/doc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package modernize provides a suite of analyzers that suggest
simplifications to Go code, using modern language and library
features.

Each diagnostic provides a fix. Our intent is that these fixes may
be safely applied en masse without changing the behavior of your
program. In some cases the suggested fixes are imperfect and may
lead to (for example) unused imports or unused local variables,
causing build breakage. However, these problems are generally
trivial to fix. We regard any modernizer whose fix changes program
behavior to have a serious bug and will endeavor to fix it.

To apply all modernization fixes en masse, you can use the
following command:

	$ go run golang.org/x/tools/go/analysis/passes/modernize/cmd/modernize@latest -fix ./...

(Do not use "go get -tool" to add gopls as a dependency of your
module; gopls commands must be built from their release branch.)

If the tool warns of conflicting fixes, you may need to run it more
than once until it has applied all fixes cleanly. This command is
not an officially supported interface and may change in the future.

Changes produced by this tool should be reviewed as usual before
being merged. In some cases, a loop may be replaced by a simple
function call, causing comments within the loop to be discarded.
Human judgment may be required to avoid losing comments of value.

The modernize suite contains many analyzers. Diagnostics from some,
such as "any" (which replaces "interface{}" with "any" where it
is safe to do so), are particularly numerous. It may ease the burden of
code review to apply fixes in two steps, the first consisting only of
fixes from the "any" analyzer, the second consisting of all
other analyzers. This can be achieved using flags, as in this example:

	$ modernize -any=true  -fix ./...
	$ modernize -any=false -fix ./...

# Analyzer appendclipped

appendclipped: simplify append chains using slices.Concat

The appendclipped analyzer suggests replacing chains of append calls with a
single call to slices.Concat, which was added in Go 1.21. For example,
append(append(s, s1...), s2...) would be simplified to slices.Concat(s, s1, s2).

In the simple case of appending to a newly allocated slice, such as
append([]T(nil), s...), the analyzer suggests the more concise slices.Clone(s).
For byte slices, it will prefer bytes.Clone if the "bytes" package is
already imported.

This fix is only applied when the base of the append tower is a
"clipped" slice, meaning its length and capacity are equal (e.g.
x[:0:0] or []T{}). This is to avoid changing program behavior by
eliminating intended side effects on the base slice's underlying
array.

This analyzer is currently disabled by default as the
transformation does not preserve the nilness of the base slice in
all cases; see https://go.dev/issue/73557.

# Analyzer atomictypes

atomictypes: replace basic types in sync/atomic calls with atomic types

The atomictypes analyzer suggests replacing the primitive sync/atomic functions with
the strongly typed atomic wrapper types introduced in Go1.19 (e.g.
atomic.Int32). For example,

	var x int32
	atomic.AddInt32(&x, 1)

would become

	var x atomic.Int32
	x.Add(1)

The atomic types are safer because they don't allow non-atomic access, which is
a common source of bugs. These types also resolve memory alignment issues that
plagued the old atomic functions on 32-bit architectures.

# Analyzer bloop

bloop: replace for-range over b.N with b.Loop

The bloop analyzer suggests replacing benchmark loops of the form
`for i := 0; i < b.N; i++` or `for range b.N` with the more modern
`for b.Loop()`, which was added in Go 1.24.

This change makes benchmark code more readable and also removes the need for
manual timer control, so any preceding calls to b.StartTimer, b.StopTimer,
or b.ResetTimer within the same function will also be removed.

Caveats: The b.Loop() method is designed to prevent the compiler from
optimizing away the benchmark loop, which can occasionally result in
slower execution due to increased allocations in some specific cases.
Since its fix may change the performance of nanosecond-scale benchmarks,
bloop is disabled by default in the `go fix` analyzer suite; see golang/go#74967.

# Analyzer any

any: replace interface{} with any

The any analyzer suggests replacing uses of the empty interface type,
`interface{}`, with the `any` alias, which was introduced in Go 1.18.
This is a purely stylistic change that makes code more readable.

# Analyzer errorsastype

errorsastype: replace errors.As with errors.AsType[T]

This analyzer suggests fixes to simplify uses of [errors.As] of
this form:

	var myerr *MyErr
	if errors.As(err, &myerr) {
		handle(myerr)
	}

by using the less error-prone generic [errors.AsType] function,
introduced in Go 1.26:

	if myerr, ok := errors.AsType[*MyErr](err); ok {
		handle(myerr)
	}

The fix is only offered if the var declaration has the form shown and
there are no uses of myerr outside the if statement.

# Analyzer fmtappendf

fmtappendf: replace []byte(fmt.Sprintf) with fmt.Appendf

The fmtappendf analyzer suggests replacing `[]byte(fmt.Sprintf(...))` with
`fmt.Appendf(nil, ...)`. This avoids the intermediate allocation of a string
by Sprintf, making the code more efficient. The suggestion also applies to
fmt.Sprint and fmt.Sprintln.

# Analyzer forvar

forvar: remove redundant re-declaration of loop variables

The forvar analyzer removes unnecessary shadowing of loop variables.
Before Go 1.22, it was common to write `for _, x := range s { x := x ... }`
to create a fresh variable for each iteration. Go 1.22 changed the semantics
of `for` loops, making this pattern redundant. This analyzer removes the
unnecessary `x := x` statement.

This fix only applies to `range` loops.

# Analyzer mapsloop

mapsloop: replace explicit loops over maps with calls to maps package

The mapsloop analyzer replaces loops of the form

	for k, v := range x { m[k] = v }

with a single call to a function from the `maps` package, added in Go 1.23.
Depending on the context, this could be `maps.Copy`, `maps.Insert`,
`maps.Clone`, or `maps.Collect`.

The transformation to `maps.Clone` is applied conservatively, as it
preserves the nilness of the source map, which may be a subtle change in
behavior if the original code did not handle a nil map in the same way.

# Analyzer minmax

minmax: replace if/else statements with calls to min or max

The minmax analyzer simplifies conditional assignments by suggesting the use
of the built-in `min` and `max` functions, introduced in Go 1.21. For example,

	if a < b { x = a } else { x = b }

is replaced by

	x = min(a, b).

This analyzer avoids making suggestions for floating-point types,
as the behavior of `min` and `max` with NaN values can differ from
the original if/else statement.

# Analyzer newexpr

newexpr: simplify code by using go1.26's new(expr)

This analyzer finds declarations of functions of this form:

	func varOf(x int) *int { return &x }

and suggests a fix to turn them into inlinable wrappers around
go1.26's built-in new(expr) function:

	//go:fix inline
	func varOf(x int) *int { return new(x) }

(The directive comment causes the 'inline' analyzer to suggest
that calls to such functions are inlined.)

In addition, this analyzer suggests a fix for each call
to one of the functions before it is transformed, so that

	use(varOf(123))

is replaced by:

	use(new(123))

Wrapper functions such as varOf are common when working with Go
serialization packages such as for JSON or protobuf, where pointers
are often used to express optionality.

# Analyzer omitzero

omitzero: suggest replacing omitempty with omitzero for struct fields

The omitzero analyzer identifies uses of the `omitempty` JSON struct
tag on fields that are themselves structs. For struct-typed fields,
the `omitempty` tag has no effect on the behavior of json.Marshal and
json.Unmarshal. The analyzer offers two suggestions: either remove the
tag, or replace it with `omitzero` (added in Go 1.24), which correctly
omits the field if the struct value is zero.

However, some other serialization packages (notably kubebuilder, see
https://book.kubebuilder.io/reference/markers.html) may have their own
interpretation of the `json:",omitzero"` tag, so removing it may affect
program behavior. For this reason, the omitzero modernizer will not
make changes in any package that contains +kubebuilder annotations.

Replacing `omitempty` with `omitzero` is a change in behavior. The
original code would always encode the struct field, whereas the
modified code will omit it if it is a zero-value.

# Analyzer plusbuild

plusbuild: remove obsolete //+build comments

The plusbuild analyzer suggests a fix to remove obsolete build tags
of the form:

	//+build linux,amd64

in files that also contain a Go 1.18-style tag such as:

	//go:build linux && amd64

(It does not check that the old and new tags are consistent;
that is the job of the 'buildtag' analyzer in the vet suite.)

# Analyzer rangeint

rangeint: replace 3-clause for loops with for-range over integers

The rangeint analyzer suggests replacing traditional for loops such
as

	for i := 0; i < n; i++ { ... }

with the more idiomatic Go 1.22 style:

	for i := range n { ... }

This transformation is applied only if (a) the loop variable is not
modified within the loop body and (b) the loop's limit expression
is not modified within the loop, as `for range` evaluates its
operand only once.

# Analyzer reflecttypefor

reflecttypefor: replace reflect.TypeOf(x) with TypeFor[T]()

This analyzer suggests fixes to replace uses of reflect.TypeOf(x) with
reflect.TypeFor, introduced in go1.22, when the desired runtime type
is known at compile time, for example:

	reflect.TypeOf(uint32(0))        -> reflect.TypeFor[uint32]()
	reflect.TypeOf((*ast.File)(nil)) -> reflect.TypeFor[*ast.File]()

It also offers a fix to simplify the constructions below, which use
reflect.TypeOf to return the runtime type for an interface type,

	reflect.TypeOf((*io.Reader)(nil)).Elem()

or:

	reflect.TypeOf([]io.Reader(nil)).Elem()

to:

	reflect.TypeFor[io.Reader]()

No fix is offered in cases when the runtime type is dynamic, such as:

	var r io.Reader = ...
	reflect.TypeOf(r)

or when the operand has potential side effects.

# Analyzer slicescontains

slicescontains: replace loops with slices.Contains or slices.ContainsFunc

The slicescontains analyzer simplifies loops that check for the existence of
an element in a slice. It replaces them with calls to `slices.Contains` or
`slices.ContainsFunc`, which were added in Go 1.21.

If the expression for the target element has side effects, this
transformation will cause those effects to occur only once, not
once per tested slice element.

# Analyzer slicesdelete

slicesdelete: replace append-based slice deletion with slices.Delete

The slicesdelete analyzer suggests replacing the idiom

	s = append(s[:i], s[j:]...)

with the more explicit

	s = slices.Delete(s, i, j)

introduced in Go 1.21.

This analyzer is disabled by default. The `slices.Delete` function
zeros the elements between the new length and the old length of the
slice to prevent memory leaks, which is a subtle difference in
behavior compared to the append-based idiom; see https://go.dev/issue/73686.

# Analyzer slicessort

slicessort: replace sort.Slice with slices.Sort for basic types

The slicessort analyzer simplifies sorting slices of basic ordered
types. It replaces

	sort.Slice(s, func(i, j int) bool { return s[i] < s[j] })

with the simpler `slices.Sort(s)`, which was added in Go 1.21.

# Analyzer stditerators

stditerators: use iterators instead of Len/At-style APIs

This analyzer suggests a fix to replace each loop of the form:

	for i := 0; i < x.Len(); i++ {
		use(x.At(i))
	}

or its "for elem := range x.Len()" equivalent by a range loop over an
iterator offered by the same data type:

	for elem := range x.All() {
		use(x.At(i)
	}

where x is one of various well-known types in the standard library.

# Analyzer stringscut

stringscut: replace strings.Index etc. with strings.Cut

This analyzer replaces certain patterns of use of [strings.Index] and string slicing by [strings.Cut], added in go1.18.

For example:

	idx := strings.Index(s, substr)
	if idx >= 0 {
	    return s[:idx]
	}

is replaced by:

	before, _, ok := strings.Cut(s, substr)
	if ok {
	    return before
	}

And:

	idx := strings.Index(s, substr)
	if idx >= 0 {
	    return
	}

is replaced by:

	found := strings.Contains(s, substr)
	if found {
	    return
	}

It also handles variants using [strings.IndexByte] instead of Index, or the bytes package instead of strings.

Fixes are offered only in cases in which there are no potential modifications of the idx, s, or substr expressions between their definition and use.

# Analyzer stringscutprefix

stringscutprefix: replace HasPrefix/TrimPrefix with CutPrefix

The stringscutprefix analyzer simplifies a common pattern where code first
checks for a prefix with `strings.HasPrefix` and then removes it with
`strings.TrimPrefix`. It replaces this two-step process with a single call
to `strings.CutPrefix`, introduced in Go 1.20. The analyzer also handles
the equivalent functions in the `bytes` package.

For example, this input:

	if strings.HasPrefix(s, prefix) {
	    use(strings.TrimPrefix(s, prefix))
	}

is fixed to:

	if after, ok := strings.CutPrefix(s, prefix); ok {
	    use(after)
	}

The analyzer also offers fixes to use CutSuffix in a similar way.
This input:

	if strings.HasSuffix(s, suffix) {
	    use(strings.TrimSuffix(s, suffix))
	}

is fixed to:

	if before, ok := strings.CutSuffix(s, suffix); ok {
	    use(before)
	}

# Analyzer stringsseq

stringsseq: replace ranging over Split/Fields with SplitSeq/FieldsSeq

The stringsseq analyzer improves the efficiency of iterating over substrings.
It replaces

	for range strings.Split(...)

with the more efficient

	for range strings.SplitSeq(...)

which was added in Go 1.24 and avoids allocating a slice for the
substrings. The analyzer also handles strings.Fields and the
equivalent functions in the bytes package.

# Analyzer stringsbuilder

stringsbuilder: replace += with strings.Builder

This analyzer replaces repeated string += string concatenation
operations with calls to Go 1.10's strings.Builder.

For example:

	var s = "["
	for x := range seq {
		s += x
		s += "."
	}
	s += "]"
	use(s)

is replaced by:

	var s strings.Builder
	s.WriteString("[")
	for x := range seq {
		s.WriteString(x)
		s.WriteString(".")
	}
	s.WriteString("]")
	use(s.String())

This avoids quadratic memory allocation and improves performance.

The analyzer requires that all references to s before the final uses
are += operations. To avoid warning about trivial cases, at least one
must appear within a loop. The variable s must be a local
variable, not a global or parameter.

All uses of the finished string must come after the last += operation.
Each such use will be replaced by a call to strings.Builder's String method.
(These may appear within an intervening loop or function literal, since even
if s.String() is called repeatedly, it does not allocate memory.)

Often the addend is a call to fmt.Sprintf, as in this example:

	var s string
	for x := range seq {
		s += fmt.Sprintf("%v", x)
	}

which, once the suggested fix is applied, becomes:

	var s strings.Builder
	for x := range seq {
		s.WriteString(fmt.Sprintf("%v", x))
	}

The WriteString call can be further simplified to the more efficient
fmt.Fprintf(&s, "%v", x), avoiding the allocation of an intermediary.
However, stringsbuilder does not perform this simplification;
it requires staticcheck analyzer QF1012. (See https://go.dev/issue/76918.)

# Analyzer testingcontext

testingcontext: replace context.WithCancel with t.Context in tests

The testingcontext analyzer simplifies context management in tests. It
replaces the manual creation of a cancellable context,

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

with a single call to t.Context(), which was added in Go 1.24.

This change is only suggested if the `cancel` function is not used
for any other purpose.

# Analyzer unsafefuncs

unsafefuncs: replace unsafe pointer arithmetic with function calls

The unsafefuncs analyzer simplifies pointer arithmetic expressions by
replacing them with calls to helper functions such as unsafe.Add,
added in Go 1.17.

Example:

	unsafe.Pointer(uintptr(ptr) + uintptr(n))

where ptr is an unsafe.Pointer, is replaced by:

	unsafe.Add(ptr, n)

# Analyzer waitgroupgo

waitgroupgo: replace wg.Add(1)/go/wg.Done() with wg.Go

The waitgroupgo analyzer simplifies goroutine management with `sync.WaitGroup`.
It replaces the common pattern

	wg.Add(1)
	go func() {
		defer wg.Done()
		...
	}()

with a single call to

	wg.Go(func(){ ... })

which was added in Go 1.25.
*/
package modernize


================================================
FILE: go/analysis/passes/modernize/errorsastype.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/token"
	"go/types"

	"fmt"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var errorsastypeAnalyzer = &analysis.Analyzer{
	Name:     "errorsastype",
	Doc:      analyzerutil.MustExtractDoc(doc, "errorsastype"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#errorsastype",
	Requires: []*analysis.Analyzer{typeindexanalyzer.Analyzer},
	Run:      errorsastype,
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.ErrorsAsTypeModernizer = errorsastypeAnalyzer
}

// errorsastype offers a fix to replace error.As with the newer
// errors.AsType[T] following this pattern:
//
//	var myerr *MyErr
//	if errors.As(err, &myerr) { ... }
//
// =>
//
//	if myerr, ok := errors.AsType[*MyErr](err); ok  { ... }
//
// (In principle several of these can then be chained using if/else,
// but we don't attempt that.)
//
// We offer the fix only within an if statement, but not within a
// switch case such as:
//
//	var myerr *MyErr
//	switch {
//	case errors.As(err, &myerr):
//	}
//
// because the transformation in that case would be ungainly.
//
// Note that the cmd/vet suite includes the "errorsas" analyzer, which
// detects actual mistakes in the use of errors.As. This logic does
// not belong in errorsas because the problems it fixes are merely
// stylistic.
//
// TODO(adonovan): support more cases:
//
//   - Negative cases
//     var myerr E
//     if !errors.As(err, &myerr) { ... }
//     =>
//     myerr, ok := errors.AsType[E](err)
//     if !ok { ... }
//
// - if myerr := new(E); errors.As(err, myerr); { ... }
//
// - if errors.As(err, myerr) && othercond { ... }
func errorsastype(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	for curCall := range index.Calls(index.Object("errors", "As")) {
		call := curCall.Node().(*ast.CallExpr)
		if len(call.Args) < 2 {
			continue // spread call: errors.As(pair())
		}

		v, curDeclStmt := canUseErrorsAsType(info, index, curCall)
		if v == nil {
			continue
		}

		file := astutil.EnclosingFile(curDeclStmt)
		if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_26) {
			continue // errors.AsType is too new
		}

		// Locate identifier "As" in errors.As.
		var asIdent *ast.Ident
		switch n := ast.Unparen(call.Fun).(type) {
		case *ast.Ident:
			asIdent = n // "errors" was dot-imported
		case *ast.SelectorExpr:
			asIdent = n.Sel
		default:
			panic("no Ident for errors.As")
		}

		// Format the type as valid Go syntax.
		// TODO(adonovan): fix: FileQualifier needs to respect
		// visibility at the current point, and either fail
		// or edit the imports as needed.
		// TODO(adonovan): fix: TypeString is not a sound way
		// to print types as Go syntax as it does not respect
		// symbol visibility, etc. We need something loosely
		// integrated with FileQualifier that accumulates
		// import edits, and may fail (e.g. for unexported
		// type or field names from other packages).
		// See https://go.dev/issues/75604.
		qual := typesinternal.FileQualifier(file, pass.Pkg)
		errtype := types.TypeString(v.Type(), qual)

		// Choose a name for the "ok" variable.
		// We generate a new name only if 'ok' is already declared at
		// curCall and it also used within the if-statement.
		curIf := curCall.Parent()
		ifScope := info.Scopes[curIf.Node().(*ast.IfStmt)]
		okName := freshName(info, index, ifScope, v.Pos(), curCall, curIf, token.NoPos, "ok")

		pass.Report(analysis.Diagnostic{
			Pos:     call.Fun.Pos(),
			End:     call.Fun.End(),
			Message: fmt.Sprintf("errors.As can be simplified using AsType[%s]", errtype),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: fmt.Sprintf("Replace errors.As with AsType[%s]", errtype),
				TextEdits: append(
					// delete "var myerr *MyErr"
					refactor.DeleteStmt(pass.Fset.File(call.Fun.Pos()), curDeclStmt),
					// if              errors.As            (err, &myerr)     { ... }
					//    -------------       --------------    -------- ----
					// if myerr, ok := errors.AsType[*MyErr](err        ); ok { ... }
					analysis.TextEdit{
						// insert "myerr, ok := "
						Pos:     call.Pos(),
						End:     call.Pos(),
						NewText: fmt.Appendf(nil, "%s, %s := ", v.Name(), okName),
					},
					analysis.TextEdit{
						// replace As with AsType[T]
						Pos:     asIdent.Pos(),
						End:     asIdent.End(),
						NewText: fmt.Appendf(nil, "AsType[%s]", errtype),
					},
					analysis.TextEdit{
						// delete ", &myerr"
						Pos: call.Args[0].End(),
						End: call.Args[1].End(),
					},
					analysis.TextEdit{
						// insert "; ok"
						Pos:     call.End(),
						End:     call.End(),
						NewText: fmt.Appendf(nil, "; %s", okName),
					},
				),
			}},
		})
	}
	return nil, nil
}

// canUseErrorsAsType reports whether curCall is a call to
// errors.As beneath an if statement, preceded by a
// declaration of the typed error var. The var must not be
// used outside the if statement.
func canUseErrorsAsType(info *types.Info, index *typeindex.Index, curCall inspector.Cursor) (_ *types.Var, _ inspector.Cursor) {
	if curCall.ParentEdgeKind() != edge.IfStmt_Cond {
		return // not beneath if statement
	}
	var (
		curIfStmt = curCall.Parent()
		ifStmt    = curIfStmt.Node().(*ast.IfStmt)
	)
	if ifStmt.Init != nil {
		return // if statement already has an init part
	}
	unary, ok := curCall.Node().(*ast.CallExpr).Args[1].(*ast.UnaryExpr)
	if !ok || unary.Op != token.AND {
		return // 2nd arg is not &var
	}
	id, ok := unary.X.(*ast.Ident)
	if !ok {
		return // not a simple ident (local var)
	}
	v := info.Uses[id].(*types.Var)
	curDef, ok := index.Def(v)
	if !ok {
		return // var is not local (e.g. dot-imported)
	}
	// Have: if errors.As(err, &v) { ... }

	// Reject if v is used outside (before or after) the
	// IfStmt, since that will become its new scope.
	for curUse := range index.Uses(v) {
		if !curIfStmt.Contains(curUse) {
			return // v used before/after if statement
		}
	}
	if curDef.ParentEdgeKind() != edge.ValueSpec_Names {
		return // v not declared by "var v T"
	}
	var (
		curSpec = curDef.Parent()  // ValueSpec
		curDecl = curSpec.Parent() // GenDecl
		spec    = curSpec.Node().(*ast.ValueSpec)
	)
	if len(spec.Names) != 1 || len(spec.Values) != 0 ||
		len(curDecl.Node().(*ast.GenDecl).Specs) != 1 {
		return // not a simple "var v T" decl
	}

	// Have:
	//   var v *MyErr
	//   ...
	//   if errors.As(err, &v) { ... }
	// with no uses of v outside the IfStmt.
	return v, curDecl.Parent() // DeclStmt
}


================================================
FILE: go/analysis/passes/modernize/fmtappendf.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/fmtstr"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var FmtAppendfAnalyzer = &analysis.Analyzer{
	Name: "fmtappendf",
	Doc:  analyzerutil.MustExtractDoc(doc, "fmtappendf"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: fmtappendf,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#fmtappendf",
}

// The fmtappend function replaces []byte(fmt.Sprintf(...)) by
// fmt.Appendf(nil, ...), and similarly for Sprint, Sprintln.
func fmtappendf(pass *analysis.Pass) (any, error) {
	index := pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	for _, fn := range []types.Object{
		index.Object("fmt", "Sprintf"),
		index.Object("fmt", "Sprintln"),
		index.Object("fmt", "Sprint"),
	} {
		for curCall := range index.Calls(fn) {
			call := curCall.Node().(*ast.CallExpr)
			if ek, idx := curCall.ParentEdge(); ek == edge.CallExpr_Args && idx == 0 {
				// Is parent a T(fmt.SprintX(...)) conversion?
				conv := curCall.Parent().Node().(*ast.CallExpr)
				info := pass.TypesInfo
				tv := info.Types[conv.Fun]
				if tv.IsType() && types.Identical(tv.Type, byteSliceType) {
					// Have: []byte(fmt.SprintX(...))
					if len(call.Args) == 0 {
						continue
					}
					// fmt.Sprint(f) and fmt.Append(f) have different nil semantics
					// when the format produces an empty string:
					// []byte(fmt.Sprintf("")) returns an empty but non-nil
					// []byte{}, while fmt.Appendf(nil, "") returns nil) so we
					// should skip these cases.
					if fn.Name() == "Sprint" || fn.Name() == "Sprintf" {
						format := info.Types[call.Args[0]].Value
						if format != nil && mayFormatEmpty(constant.StringVal(format)) {
							continue
						}
					}

					// Find "Sprint" identifier.
					var id *ast.Ident
					switch e := ast.Unparen(call.Fun).(type) {
					case *ast.SelectorExpr:
						id = e.Sel // "fmt.Sprint"
					case *ast.Ident:
						id = e // "Sprint" after `import . "fmt"`
					}

					old, new := fn.Name(), strings.Replace(fn.Name(), "Sprint", "Append", 1)
					edits := []analysis.TextEdit{
						{
							// Delete "[]byte(", including any spaces before the first argument.
							Pos: conv.Pos(),
							End: conv.Args[0].Pos(), // always exactly one argument in a valid byte slice conversion
						},
						{
							// Delete ")", including any non-args (space or
							// commas) that come before the right parenthesis.
							// Leaving an extra comma here produces invalid
							// code. (See golang/go#74709)
							// Unfortunately, this and the edit above may result
							// in deleting some comments.
							Pos: conv.Args[0].End(),
							End: conv.Rparen + 1,
						},
						{
							Pos:     id.Pos(),
							End:     id.End(),
							NewText: []byte(new),
						},
						{
							Pos:     call.Lparen + 1,
							NewText: []byte("nil, "),
						},
					}
					if !analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(curCall), versions.Go1_19) {
						continue
					}
					pass.Report(analysis.Diagnostic{
						Pos:     conv.Pos(),
						End:     conv.End(),
						Message: fmt.Sprintf("Replace []byte(fmt.%s...) with fmt.%s", old, new),
						SuggestedFixes: []analysis.SuggestedFix{{
							Message:   fmt.Sprintf("Replace []byte(fmt.%s...) with fmt.%s", old, new),
							TextEdits: edits,
						}},
					})
				}
			}
		}
	}
	return nil, nil
}

// mayFormatEmpty reports whether fmt.Sprintf might produce an empty string.
// It returns false in the following two cases:
//  1. formatStr contains non-operation characters.
//  2. formatStr contains formatting verbs besides s, v, x, X (verbs which may
//     produce empty results)
//
// In all other cases it returns true.
func mayFormatEmpty(formatStr string) bool {
	if formatStr == "" {
		return true
	}
	operations, err := fmtstr.Parse(formatStr, 0)
	if err != nil {
		// If formatStr is malformed, the printf analyzer will report a
		// diagnostic, so we can ignore this error.
		// Calling Parse on a string without % formatters also returns an error,
		// in which case we can safely return false.
		return false
	}
	totalOpsLen := 0
	for _, op := range operations {
		totalOpsLen += len(op.Text)
		if !strings.ContainsRune("svxX", rune(op.Verb.Verb)) && op.Prec.Fixed != 0 {
			// A non [s, v, x, X] formatter with non-zero precision cannot
			// produce an empty string.
			return false
		}
	}
	// If the format string contains non-operation characters, it cannot produce
	// the empty string.
	if totalOpsLen != len(formatStr) {
		return false
	}
	// If we get here, it means that all formatting verbs are %s, %v, %x, %X,
	// and there are no additional non-operation characters. We conservatively
	// report that this may format as an empty string, ignoring uses of
	// precision and the values of the formatter args.
	return true
}


================================================
FILE: go/analysis/passes/modernize/forvar.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/versions"
)

var ForVarAnalyzer = &analysis.Analyzer{
	Name:     "forvar",
	Doc:      analyzerutil.MustExtractDoc(doc, "forvar"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      forvar,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#forvar",
}

// forvar offers to fix unnecessary copying of a for variable
//
//	for _, x := range foo {
//		x := x // offer to remove this superfluous assignment
//	}
//
// Prerequisites:
// First statement in a range loop has to be <ident> := <ident>
// where the two idents are the same,
// and the ident is defined (:=) as a variable in the for statement.
// (Note that this 'fix' does not work for three clause loops
// because the Go spec says "The variable used by each subsequent iteration
// is declared implicitly before executing the post statement and initialized to the
// value of the previous iteration's variable at that moment.")
//
// Variant: same thing in an IfStmt.Init, when the IfStmt is the sole
// loop body statement:
//
//	for _, x := range foo {
//		if x := x; cond { ... }
//	}
//
// (The restriction is necessary to avoid potential problems arising
// from merging two distinct variables.)
//
// This analyzer is synergistic with stditerators,
// which may create redundant "x := x" statements.
func forvar(pass *analysis.Pass) (any, error) {
	for curFile := range filesUsingGoVersion(pass, versions.Go1_22) {
		for curLoop := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			loop := curLoop.Node().(*ast.RangeStmt)
			if loop.Tok != token.DEFINE {
				continue
			}
			isLoopVarRedecl := func(stmt ast.Stmt) bool {
				if assign, ok := stmt.(*ast.AssignStmt); ok &&
					assign.Tok == token.DEFINE &&
					len(assign.Lhs) == len(assign.Rhs) {

					for i, lhs := range assign.Lhs {
						if !(astutil.EqualSyntax(lhs, assign.Rhs[i]) &&
							(astutil.EqualSyntax(lhs, loop.Key) ||
								astutil.EqualSyntax(lhs, loop.Value))) {
							return false
						}
					}
					return true
				}
				return false
			}
			// Have: for k, v := range x { stmts }
			//
			// Delete the prefix of stmts that are
			// of the form k := k; v := v; k, v := k, v; v, k := v, k.
			for _, stmt := range loop.Body.List {
				if isLoopVarRedecl(stmt) {
					// { x := x; ... }
					//   ------
				} else if ifstmt, ok := stmt.(*ast.IfStmt); ok &&
					ifstmt.Init != nil &&
					len(loop.Body.List) == 1 && // must be sole statement in loop body
					isLoopVarRedecl(ifstmt.Init) {
					// if x := x; cond {
					//    ------
					stmt = ifstmt.Init
				} else {
					break // stop at first other statement
				}

				curStmt, _ := curLoop.FindNode(stmt)
				edits := refactor.DeleteStmt(pass.Fset.File(stmt.Pos()), curStmt)
				if len(edits) > 0 {
					pass.Report(analysis.Diagnostic{
						Pos:     stmt.Pos(),
						End:     stmt.End(),
						Message: "copying variable is unneeded",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message:   "Remove unneeded redeclaration",
							TextEdits: edits,
						}},
					})
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/maps.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

// This file defines modernizers that use the "maps" package.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

var MapsLoopAnalyzer = &analysis.Analyzer{
	Name:     "mapsloop",
	Doc:      analyzerutil.MustExtractDoc(doc, "mapsloop"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      mapsloop,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#mapsloop",
}

// The mapsloop pass offers to simplify a loop of map insertions:
//
//	for k, v := range x {
//		m[k] = v
//	}
//
// by a call to go1.23's maps package. There are four variants, the
// product of two axes: whether the source x is a map or an iter.Seq2,
// and whether the destination m is a newly created map:
//
//	maps.Copy(m, x)		(x is map)
//	maps.Insert(m, x)       (x is iter.Seq2)
//	m = maps.Clone(x)       (x is a non-nil map, m is a new map)
//	m = maps.Collect(x)     (x is iter.Seq2, m is a new map)
//
// A map is newly created if the preceding statement has one of these
// forms, where M is a map type:
//
//	m = make(M)
//	m = M{}
func mapsloop(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "maps", "bytes", "runtime") {
		return nil, nil
	}

	info := pass.TypesInfo

	// check is called for each statement of this form:
	//   for k, v := range x { m[k] = v }
	check := func(file *ast.File, curRange inspector.Cursor, assign *ast.AssignStmt, m, x ast.Expr) {

		// Is x a map or iter.Seq2?
		tx := types.Unalias(info.TypeOf(x))
		var xmap bool
		switch typeparams.CoreType(tx).(type) {
		case *types.Map:
			xmap = true

		case *types.Signature:
			k, v, ok := assignableToIterSeq2(tx)
			if !ok {
				return // a named isomer of Seq2
			}
			xmap = false

			// Record in tx the unnamed map[K]V type
			// derived from the yield function.
			// This is the type of maps.Collect(x).
			tx = types.NewMap(k, v)

		default:
			return // e.g. slice, channel (or no core type!)
		}

		// Is the preceding statement of the form
		//    m = make(M) or M{}
		// and can we replace its RHS with slices.{Clone,Collect}?
		//
		// Beware: if x may be nil, we cannot use Clone as it preserves nilness.
		var mrhs ast.Expr // make(M) or M{}, or nil
		if curPrev, ok := curRange.PrevSibling(); ok {
			if assign, ok := curPrev.Node().(*ast.AssignStmt); ok &&
				len(assign.Lhs) == 1 &&
				len(assign.Rhs) == 1 &&
				astutil.EqualSyntax(assign.Lhs[0], m) {

				// Have: m = rhs; for k, v := range x { m[k] = v }
				var newMap bool
				rhs := assign.Rhs[0]
				switch rhs := ast.Unparen(rhs).(type) {
				case *ast.CallExpr:
					if id, ok := ast.Unparen(rhs.Fun).(*ast.Ident); ok &&
						info.Uses[id] == builtinMake {
						// Have: m = make(...)
						newMap = true
					}
				case *ast.CompositeLit:
					if len(rhs.Elts) == 0 {
						// Have m = M{}
						newMap = true
					}
				}

				// Take care not to change type of m's RHS expression.
				if newMap {
					trhs := info.TypeOf(rhs)

					// Inv: tx is the type of maps.F(x)
					// - maps.Clone(x) has the same type as x.
					// - maps.Collect(x) returns an unnamed map type.

					if assign.Tok == token.DEFINE {
						// DEFINE (:=): we must not
						// change the type of RHS.
						if types.Identical(tx, trhs) {
							mrhs = rhs
						}
					} else {
						// ASSIGN (=): the types of LHS
						// and RHS may differ in namedness.
						if types.AssignableTo(tx, trhs) {
							mrhs = rhs
						}
					}

					// Temporarily disable the transformation to the
					// (nil-preserving) maps.Clone until we can prove
					// that x is non-nil. This is rarely possible,
					// and may require control flow analysis
					// (e.g. a dominating "if len(x)" check).
					// See #71844.
					if xmap {
						mrhs = nil
					}
				}
			}
		}

		// Choose function.
		var funcName string
		if mrhs != nil {
			funcName = cond(xmap, "Clone", "Collect")
		} else {
			funcName = cond(xmap, "Copy", "Insert")
		}

		// Report diagnostic, and suggest fix.
		rng := curRange.Node()
		prefix, importEdits := refactor.AddImport(info, file, "maps", "maps", funcName, rng.Pos())
		var (
			newText    []byte
			start, end token.Pos
		)
		if mrhs != nil {
			// Replace assignment and loop with expression.
			//
			//   m = make(...)
			//   for k, v := range x { /* comments */ m[k] = v }
			//
			//   ->
			//
			//   /* comments */
			//   m = maps.Copy(x)
			curPrev, _ := curRange.PrevSibling()
			start, end = curPrev.Node().Pos(), rng.End()
			newText = fmt.Appendf(nil, "%s%s = %s%s(%s)",
				allComments(file, start, end),
				astutil.Format(pass.Fset, m),
				prefix,
				funcName,
				astutil.Format(pass.Fset, x))
		} else {
			// Replace loop with call statement.
			//
			//   for k, v := range x { /* comments */ m[k] = v }
			//
			//   ->
			//
			//   /* comments */
			//   maps.Copy(m, x)
			start, end = rng.Pos(), rng.End()
			newText = fmt.Appendf(nil, "%s%s%s(%s, %s)",
				allComments(file, start, end),
				prefix,
				funcName,
				astutil.Format(pass.Fset, m),
				astutil.Format(pass.Fset, x))
		}
		pass.Report(analysis.Diagnostic{
			Pos:     assign.Lhs[0].Pos(),
			End:     assign.Lhs[0].End(),
			Message: "Replace m[k]=v loop with maps." + funcName,
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Replace m[k]=v loop with maps." + funcName,
				TextEdits: append(importEdits, []analysis.TextEdit{{
					Pos:     start,
					End:     end,
					NewText: newText,
				}}...),
			}},
		})

	}

	// Find all range loops around m[k] = v.
	for curFile := range filesUsingGoVersion(pass, versions.Go1_23) {
		file := curFile.Node().(*ast.File)

		for curRange := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			rng := curRange.Node().(*ast.RangeStmt)

			if rng.Tok == token.DEFINE &&
				rng.Key != nil &&
				rng.Value != nil &&
				isAssignBlock(rng.Body) {
				// Have: for k, v := range x { lhs = rhs }

				assign := rng.Body.List[0].(*ast.AssignStmt)

				// usesKV reports whether e references vars k or v.
				usesKV := func(e ast.Expr) bool {
					k := info.Defs[rng.Key.(*ast.Ident)]
					v := info.Defs[rng.Value.(*ast.Ident)]
					for n := range ast.Preorder(e) {
						if id, ok := n.(*ast.Ident); ok {
							obj := info.Uses[id]
							if obj != nil && // don't rely on k, v being non-nil
								(obj == k || obj == v) {
								return true
							}
						}
					}
					return false
				}

				if index, ok := assign.Lhs[0].(*ast.IndexExpr); ok &&
					len(assign.Lhs) == 1 &&
					astutil.EqualSyntax(rng.Key, index.Index) &&
					astutil.EqualSyntax(rng.Value, assign.Rhs[0]) &&
					!usesKV(index.X) { // reject (e.g.) f(k, v)[k] = v
					if tmap, ok := typeparams.CoreType(info.TypeOf(index.X)).(*types.Map); ok &&
						types.Identical(info.TypeOf(index), info.TypeOf(rng.Value)) && // m[k], v
						types.Identical(tmap.Key(), info.TypeOf(rng.Key)) {

						// Have: for k, v := range x { m[k] = v }
						// where there is no implicit conversion
						// of either key or value.
						check(file, curRange, assign, index.X, rng.X)
					}
				}
			}
		}
	}
	return nil, nil
}

// assignableToIterSeq2 reports whether t is assignable to
// iter.Seq[K, V] and returns K and V if so.
func assignableToIterSeq2(t types.Type) (k, v types.Type, ok bool) {
	// The only named type assignable to iter.Seq2 is iter.Seq2.
	if is[*types.Named](t) {
		if !typesinternal.IsTypeNamed(t, "iter", "Seq2") {
			return
		}
		t = t.Underlying()
	}

	if t, ok := t.(*types.Signature); ok {
		// func(yield func(K, V) bool)?
		if t.Params().Len() == 1 && t.Results().Len() == 0 {
			if yield, ok := t.Params().At(0).Type().(*types.Signature); ok { // sic, no Underlying/CoreType
				if yield.Params().Len() == 2 &&
					yield.Results().Len() == 1 &&
					types.Identical(yield.Results().At(0).Type(), builtinBool.Type()) {
					return yield.Params().At(0).Type(), yield.Params().At(1).Type(), true
				}
			}
		}
	}
	return
}


================================================
FILE: go/analysis/passes/modernize/minmax.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var MinMaxAnalyzer = &analysis.Analyzer{
	Name: "minmax",
	Doc:  analyzerutil.MustExtractDoc(doc, "minmax"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: minmax,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#minmax",
}

// The minmax pass replaces if/else statements with calls to min or max,
// and removes user-defined min/max functions that are equivalent to built-ins.
//
// If/else replacement patterns:
//
//  1. if a < b { x = a } else { x = b }        =>      x = min(a, b)
//  2. x = a; if a < b { x = b }                =>      x = max(a, b)
//
// Pattern 1 requires that a is not NaN, and pattern 2 requires that b
// is not Nan. Since this is hard to prove, we reject floating-point
// numbers.
//
// Function removal:
// User-defined min/max functions are suggested for removal if they may
// be safely replaced by their built-in namesake.
//
// Variants:
// - all four ordered comparisons
// - "x := a" or "x = a" or "var x = a" in pattern 2
// - "x < b" or "a < b" in pattern 2
func minmax(pass *analysis.Pass) (any, error) {
	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info    = pass.TypesInfo
	)
	// Check for user-defined min/max functions that can be removed
	checkUserDefinedMinMax(pass)

	// check is called for all statements of this form:
	//   if a < b { lhs = rhs }
	check := func(file *ast.File, curIfStmt inspector.Cursor, compare *ast.BinaryExpr) {
		var (
			ifStmt  = curIfStmt.Node().(*ast.IfStmt)
			tassign = ifStmt.Body.List[0].(*ast.AssignStmt)
			a       = compare.X
			b       = compare.Y
			lhs     = tassign.Lhs[0]
			rhs     = tassign.Rhs[0]
			sign    = isInequality(compare.Op)

			// callArg formats a call argument, preserving comments from [start-end).
			callArg = func(arg ast.Expr, start, end token.Pos) string {
				comments := allComments(file, start, end)
				return cond(arg == b, ", ", "") + // second argument needs a comma
					cond(comments != "", "\n", "") + // comments need their own line
					comments +
					astutil.Format(pass.Fset, arg)
			}
		)

		if fblock, ok := ifStmt.Else.(*ast.BlockStmt); ok && isAssignBlock(fblock) {
			fassign := fblock.List[0].(*ast.AssignStmt)

			// Have: if a < b { lhs = rhs } else { lhs2 = rhs2 }
			lhs2 := fassign.Lhs[0]
			rhs2 := fassign.Rhs[0]

			// For pattern 1, check that:
			// - lhs = lhs2
			// - {rhs,rhs2} = {a,b}
			if astutil.EqualSyntax(lhs, lhs2) {
				if astutil.EqualSyntax(rhs, a) && astutil.EqualSyntax(rhs2, b) {
					sign = +sign
				} else if astutil.EqualSyntax(rhs2, a) && astutil.EqualSyntax(rhs, b) {
					sign = -sign
				} else {
					return
				}

				sym := cond(sign < 0, "min", "max")

				if !is[*types.Builtin](lookup(pass.TypesInfo, curIfStmt, sym)) {
					return // min/max function is shadowed
				}
				if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_21) {
					return // min/max is too new
				}

				// pattern 1
				//
				// TODO(adonovan): if lhs is declared "var lhs T" on preceding line,
				// simplify the whole thing to "lhs := min(a, b)".
				pass.Report(analysis.Diagnostic{
					// Highlight the condition a < b.
					Pos:     compare.Pos(),
					End:     compare.End(),
					Message: fmt.Sprintf("if/else statement can be modernized using %s", sym),
					SuggestedFixes: []analysis.SuggestedFix{{
						Message: fmt.Sprintf("Replace if statement with %s", sym),
						TextEdits: []analysis.TextEdit{{
							// Replace IfStmt with lhs = min(a, b).
							Pos: ifStmt.Pos(),
							End: ifStmt.End(),
							NewText: fmt.Appendf(nil, "%s = %s(%s%s)",
								astutil.Format(pass.Fset, lhs),
								sym,
								callArg(a, ifStmt.Pos(), ifStmt.Else.Pos()),
								callArg(b, ifStmt.Else.Pos(), ifStmt.End()),
							),
						}},
					}},
				})
			}

		} else if prev, ok := curIfStmt.PrevSibling(); ok && isSimpleAssign(prev.Node()) && ifStmt.Else == nil {
			fassign := prev.Node().(*ast.AssignStmt)

			// Have: lhs0 = rhs0; if a < b { lhs = rhs }
			//
			// For pattern 2, check that
			// - lhs = lhs0
			// - {a,b} = {rhs,rhs0} or {rhs,lhs0}
			//   The replacement must use rhs0 not lhs0 though.
			//   For example, we accept this variant:
			//     lhs = x; if lhs < y { lhs = y }   =>   lhs = min(x, y), not min(lhs, y)
			//
			// TODO(adonovan): accept "var lhs0 = rhs0" form too.
			lhs0 := fassign.Lhs[0]
			rhs0 := fassign.Rhs[0]

			// If the assignment occurs within a select
			// comms clause (like "case lhs0 := <-rhs0:"),
			// there's no way of rewriting it into a min/max call.
			if prev.ParentEdgeKind() == edge.CommClause_Comm {
				return
			}

			if astutil.EqualSyntax(lhs, lhs0) {
				if astutil.EqualSyntax(rhs, a) && (astutil.EqualSyntax(rhs0, b) || astutil.EqualSyntax(lhs0, b)) {
					sign = +sign
				} else if (astutil.EqualSyntax(rhs0, a) || astutil.EqualSyntax(lhs0, a)) && astutil.EqualSyntax(rhs, b) {
					sign = -sign
				} else {
					return
				}
				sym := cond(sign < 0, "min", "max")

				if !is[*types.Builtin](lookup(pass.TypesInfo, curIfStmt, sym)) {
					return // min/max function is shadowed
				}

				// Permit lhs0 to stand for rhs0 in the matching,
				// but don't actually reduce to lhs0 = min(lhs0, rhs)
				// since the "=" could be a ":=". Use min(rhs0, rhs).
				if astutil.EqualSyntax(lhs0, a) {
					a = rhs0
				} else if astutil.EqualSyntax(lhs0, b) {
					b = rhs0
				}

				if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_21) {
					return // min/max is too new
				}

				// pattern 2
				pass.Report(analysis.Diagnostic{
					// Highlight the condition a < b.
					Pos:     compare.Pos(),
					End:     compare.End(),
					Message: fmt.Sprintf("if statement can be modernized using %s", sym),
					SuggestedFixes: []analysis.SuggestedFix{{
						Message: fmt.Sprintf("Replace if/else with %s", sym),
						TextEdits: []analysis.TextEdit{{
							Pos: fassign.Pos(),
							End: ifStmt.End(),
							// Replace "x := a; if ... {}" with "x = min(...)", preserving comments.
							NewText: fmt.Appendf(nil, "%s %s %s(%s%s)",
								astutil.Format(pass.Fset, lhs),
								fassign.Tok.String(),
								sym,
								callArg(a, fassign.Pos(), ifStmt.Pos()),
								callArg(b, ifStmt.Pos(), ifStmt.End()),
							),
						}},
					}},
				})
			}
		}
	}

	// Find all "if a < b { lhs = rhs }" statements.
	for curIfStmt := range inspect.Root().Preorder((*ast.IfStmt)(nil)) {
		ifStmt := curIfStmt.Node().(*ast.IfStmt)
		// Don't bother handling "if a < b { lhs = rhs }" when it appears
		// as the "else" branch of another if-statement.
		//    if cond { ... } else if a < b { lhs = rhs }
		// (This case would require introducing another block
		//    if cond { ... } else { if a < b { lhs = rhs } }
		// and checking that there is no following "else".)
		if curIfStmt.ParentEdgeKind() == edge.IfStmt_Else {
			continue
		}

		if compare, ok := ifStmt.Cond.(*ast.BinaryExpr); ok &&
			ifStmt.Init == nil &&
			isInequality(compare.Op) != 0 &&
			isAssignBlock(ifStmt.Body) {
			// a blank var has no type.
			if tLHS := info.TypeOf(ifStmt.Body.List[0].(*ast.AssignStmt).Lhs[0]); tLHS != nil && !maybeNaN(tLHS) {
				// Have: if a < b { lhs = rhs }
				check(astutil.EnclosingFile(curIfStmt), curIfStmt, compare)
			}
		}
	}
	return nil, nil
}

// allComments collects all the comments from start to end.
func allComments(file *ast.File, start, end token.Pos) string {
	var buf strings.Builder
	for co := range astutil.Comments(file, start, end) {
		_, _ = fmt.Fprintf(&buf, "%s\n", co.Text)
	}
	return buf.String()
}

// isInequality reports non-zero if tok is one of < <= => >:
// +1 for > and -1 for <.
func isInequality(tok token.Token) int {
	switch tok {
	case token.LEQ, token.LSS:
		return -1
	case token.GEQ, token.GTR:
		return +1
	}
	return 0
}

// isAssignBlock reports whether b is a block of the form { lhs = rhs }.
func isAssignBlock(b *ast.BlockStmt) bool {
	if len(b.List) != 1 {
		return false
	}
	// Inv: the sole statement cannot be { lhs := rhs }.
	return isSimpleAssign(b.List[0])
}

// isSimpleAssign reports whether n has the form "lhs = rhs" or "lhs := rhs".
func isSimpleAssign(n ast.Node) bool {
	assign, ok := n.(*ast.AssignStmt)
	return ok &&
		(assign.Tok == token.ASSIGN || assign.Tok == token.DEFINE) &&
		len(assign.Lhs) == 1 &&
		len(assign.Rhs) == 1
}

// maybeNaN reports whether t is (or may be) a floating-point type.
func maybeNaN(t types.Type) bool {
	// For now, we rely on core types.
	// TODO(adonovan): In the post-core-types future,
	// follow the approach of types.Checker.applyTypeFunc.
	t = typeparams.CoreType(t)
	if t == nil {
		return true // fail safe
	}
	if basic, ok := t.(*types.Basic); ok && basic.Info()&types.IsFloat != 0 {
		return true
	}
	return false
}

// checkUserDefinedMinMax looks for user-defined min/max functions that are
// equivalent to the built-in functions and suggests removing them.
func checkUserDefinedMinMax(pass *analysis.Pass) {
	index := pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)

	// Look up min and max functions by name in package scope
	for _, funcName := range []string{"min", "max"} {
		if fn, ok := pass.Pkg.Scope().Lookup(funcName).(*types.Func); ok {
			// Use typeindex to get the FuncDecl directly
			if def, ok := index.Def(fn); ok {
				decl := def.Parent().Node().(*ast.FuncDecl)
				// Check if this function matches the built-in min/max signature
				// and behavior, and verify that we have go1.21.
				if canUseBuiltinMinMax(fn, decl.Body) &&
					analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(def), versions.Go1_21) {
					// Expand to include leading doc comment
					pos := decl.Pos()
					if docs := astutil.DocComment(decl); docs != nil {
						pos = docs.Pos()
					}

					pass.Report(analysis.Diagnostic{
						Pos:     decl.Pos(),
						End:     decl.End(),
						Message: fmt.Sprintf("user-defined %s function is equivalent to built-in %s and can be removed", funcName, funcName),
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: fmt.Sprintf("Remove user-defined %s function", funcName),
							TextEdits: []analysis.TextEdit{{
								Pos: pos,
								End: decl.End(),
							}},
						}},
					})
				}
			}
		}
	}
}

// canUseBuiltinMinMax reports whether it is safe to replace a call
// to this min or max function by its built-in namesake.
func canUseBuiltinMinMax(fn *types.Func, body *ast.BlockStmt) bool {
	sig := fn.Type().(*types.Signature)

	// Only consider the most common case: exactly 2 parameters
	if sig.Params().Len() != 2 {
		return false
	}

	// Check if any parameter might be floating-point
	for param := range sig.Params().Variables() {
		if maybeNaN(param.Type()) {
			return false // Don't suggest removal for float types due to NaN handling
		}
	}

	// Must have exactly one return value
	if sig.Results().Len() != 1 {
		return false
	}

	// Check that the function body implements the expected min/max logic
	if body == nil {
		return false
	}

	return hasMinMaxLogic(body, fn.Name())
}

// hasMinMaxLogic checks if the function body implements simple min/max logic.
func hasMinMaxLogic(body *ast.BlockStmt, funcName string) bool {
	// Pattern 1: Single if/else statement
	if len(body.List) == 1 {
		if ifStmt, ok := body.List[0].(*ast.IfStmt); ok {
			// Get the "false" result from the else block
			if elseBlock, ok := ifStmt.Else.(*ast.BlockStmt); ok && len(elseBlock.List) == 1 {
				if elseRet, ok := elseBlock.List[0].(*ast.ReturnStmt); ok && len(elseRet.Results) == 1 {
					return checkMinMaxPattern(ifStmt, elseRet.Results[0], funcName)
				}
			}
		}
	}

	// Pattern 2: if statement followed by return
	if len(body.List) == 2 {
		if ifStmt, ok := body.List[0].(*ast.IfStmt); ok && ifStmt.Else == nil {
			if retStmt, ok := body.List[1].(*ast.ReturnStmt); ok && len(retStmt.Results) == 1 {
				return checkMinMaxPattern(ifStmt, retStmt.Results[0], funcName)
			}
		}
	}

	return false
}

// checkMinMaxPattern checks if an if statement implements min/max logic.
// ifStmt: the if statement to check
// falseResult: the expression returned when the condition is false
// funcName: "min" or "max"
func checkMinMaxPattern(ifStmt *ast.IfStmt, falseResult ast.Expr, funcName string) bool {
	// Must have condition with comparison
	cmp, ok := ifStmt.Cond.(*ast.BinaryExpr)
	if !ok {
		return false
	}

	// Check if then branch returns one of the compared values
	if len(ifStmt.Body.List) != 1 {
		return false
	}

	thenRet, ok := ifStmt.Body.List[0].(*ast.ReturnStmt)
	if !ok || len(thenRet.Results) != 1 {
		return false
	}

	// Use the same logic as the existing minmax analyzer
	sign := isInequality(cmp.Op)
	if sign == 0 {
		return false // Not a comparison operator
	}

	t := thenRet.Results[0] // "true" result
	f := falseResult        // "false" result
	x := cmp.X              // left operand
	y := cmp.Y              // right operand

	// Check operand order and adjust sign accordingly
	if astutil.EqualSyntax(t, x) && astutil.EqualSyntax(f, y) {
		sign = +sign
	} else if astutil.EqualSyntax(t, y) && astutil.EqualSyntax(f, x) {
		sign = -sign
	} else {
		return false
	}

	// Check if the sign matches the function name
	return cond(sign < 0, "min", "max") == funcName
}

// -- utils --

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

func cond[T any](cond bool, t, f T) T {
	if cond {
		return t
	} else {
		return f
	}
}


================================================
FILE: go/analysis/passes/modernize/modernize.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	_ "embed"
	"go/ast"
	"go/constant"
	"go/format"
	"go/token"
	"go/types"
	"iter"
	"regexp"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"

	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

// Suite lists all modernize analyzers.
var Suite = []*analysis.Analyzer{
	AnyAnalyzer,
	atomicTypesAnalyzer,
	// AppendClippedAnalyzer, // not nil-preserving!
	// BLoopAnalyzer, // may skew benchmark results, see golang/go#74967
	FmtAppendfAnalyzer,
	ForVarAnalyzer,
	MapsLoopAnalyzer,
	MinMaxAnalyzer,
	NewExprAnalyzer,
	OmitZeroAnalyzer,
	plusBuildAnalyzer,
	RangeIntAnalyzer,
	ReflectTypeForAnalyzer,
	SlicesContainsAnalyzer,
	// SlicesDeleteAnalyzer, // not nil-preserving!
	SlicesSortAnalyzer,
	stditeratorsAnalyzer,
	stringscutAnalyzer,
	StringsCutPrefixAnalyzer,
	StringsSeqAnalyzer,
	StringsBuilderAnalyzer,
	TestingContextAnalyzer,
	unsafeFuncsAnalyzer,
	WaitGroupGoAnalyzer,
}

// -- helpers --

// formatExprs formats a comma-separated list of expressions.
func formatExprs(fset *token.FileSet, exprs []ast.Expr) string {
	var buf strings.Builder
	for i, e := range exprs {
		if i > 0 {
			buf.WriteString(",  ")
		}
		format.Node(&buf, fset, e) // ignore errors
	}
	return buf.String()
}

// isZeroIntConst reports whether e is an integer whose value is 0.
func isZeroIntConst(info *types.Info, e ast.Expr) bool {
	return isIntLiteral(info, e, 0)
}

// isIntLiteral reports whether e is an integer with given value.
func isIntLiteral(info *types.Info, e ast.Expr, n int64) bool {
	return info.Types[e].Value == constant.MakeInt64(n)
}

// filesUsingGoVersion returns a cursor for each *ast.File in the inspector
// that uses at least the specified version of Go (e.g. "go1.24").
//
// The pass's analyzer must require [inspect.Analyzer].
//
// TODO(adonovan): opt: eliminate this function, instead following the
// approach of [fmtappendf], which uses typeindex and
// [analyzerutil.FileUsesGoVersion]; see "Tip" documented at the
// latter function for motivation.
func filesUsingGoVersion(pass *analysis.Pass, version string) iter.Seq[inspector.Cursor] {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	return func(yield func(inspector.Cursor) bool) {
		for curFile := range inspect.Root().Children() {
			file := curFile.Node().(*ast.File)
			if analyzerutil.FileUsesGoVersion(pass, file, version) && !yield(curFile) {
				break
			}
		}
	}
}

// within reports whether the current pass is analyzing one of the
// specified standard packages or their dependencies.
func within(pass *analysis.Pass, pkgs ...string) bool {
	path := pass.Pkg.Path()
	return packagepath.IsStdPackage(path) &&
		moreiters.Contains(stdlib.Dependencies(pkgs...), path)
}

// unparenEnclosing removes enclosing parens from cur in
// preparation for a call to [Cursor.ParentEdge].
func unparenEnclosing(cur inspector.Cursor) inspector.Cursor {
	for cur.ParentEdgeKind() == edge.ParenExpr_X {
		cur = cur.Parent()
	}
	return cur
}

var (
	builtinAny     = types.Universe.Lookup("any")
	builtinAppend  = types.Universe.Lookup("append")
	builtinBool    = types.Universe.Lookup("bool")
	builtinInt     = types.Universe.Lookup("int")
	builtinFalse   = types.Universe.Lookup("false")
	builtinLen     = types.Universe.Lookup("len")
	builtinMake    = types.Universe.Lookup("make")
	builtinNew     = types.Universe.Lookup("new")
	builtinNil     = types.Universe.Lookup("nil")
	builtinString  = types.Universe.Lookup("string")
	builtinTrue    = types.Universe.Lookup("true")
	byteSliceType  = types.NewSlice(types.Typ[types.Byte])
	omitemptyRegex = regexp.MustCompile(`(?:^json| json):"[^"]*(,omitempty)(?:"|,[^"]*")\s?`)
)

// lookup returns the symbol denoted by name at the position of the cursor.
func lookup(info *types.Info, cur inspector.Cursor, name string) types.Object {
	scope := typesinternal.EnclosingScope(info, cur)
	_, obj := scope.LookupParent(name, cur.Node().Pos())
	return obj
}

func first[T any](x T, _ any) T { return x }

// freshName returns a fresh name at the given pos and scope based on preferredName.
// It generates a new name using refactor.FreshName only if:
// (a) the preferred name is already defined at definedCur, and
// (b) there are references to it from within usedCur.
// If useAfterPos.IsValid(), the references must be after
// useAfterPos within usedCur in order to warrant a fresh name.
// Otherwise, it returns preferredName, since shadowing is valid in this case.
// (declaredCur and usedCur may be identical in some use cases).
func freshName(info *types.Info, index *typeindex.Index, scope *types.Scope, pos token.Pos, defCur inspector.Cursor, useCur inspector.Cursor, useAfterPos token.Pos, preferredName string) string {
	obj := lookup(info, defCur, preferredName)
	if obj == nil {
		// preferredName has not been declared here.
		return preferredName
	}
	for use := range index.Uses(obj) {
		if useCur.Contains(use) && use.Node().Pos() >= useAfterPos {
			return refactor.FreshName(scope, pos, preferredName)
		}
	}
	// Name is taken but not used in the given block; shadowing is acceptable.
	return preferredName
}

// isLocal reports whether obj is local to some function.
// Precondition: not a struct field or interface method.
func isLocal(obj types.Object) bool {
	// [... 5=stmt 4=func 3=file 2=pkg 1=universe]
	var depth int
	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
		depth++
	}
	return depth >= 4
}


================================================
FILE: go/analysis/passes/modernize/modernize_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize_test

import (
	"testing"

	. "golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/modernize"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/testenv"
)

func TestAppendClipped(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.AppendClippedAnalyzer, "appendclipped")
}

func TestAtomicTypes(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), goplsexport.AtomicTypesModernizer, "atomictypes/...")
}
func TestBloop(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.BLoopAnalyzer, "bloop")
}

func TestAny(t *testing.T) {
	// The 'any' tests also exercise that fixes are not applied to generated files.
	RunWithSuggestedFixes(t, TestData(), modernize.AnyAnalyzer, "any")
}

func TestErrorsAsType(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), goplsexport.ErrorsAsTypeModernizer, "errorsastype/...")
}

func TestFmtAppendf(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.FmtAppendfAnalyzer, "fmtappendf")
}

func TestForVar(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.ForVarAnalyzer, "forvar")
}

func TestStdIterators(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), goplsexport.StdIteratorsModernizer, "stditerators")
}

func TestMapsLoop(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.MapsLoopAnalyzer, "mapsloop")
}

func TestMinMax(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.MinMaxAnalyzer, "minmax", "minmax/userdefined", "minmax/wrongoperators", "minmax/nonstrict", "minmax/wrongreturn", "minmax/go120")
}

func TestNewExpr(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.NewExprAnalyzer, "newexpr")
}

func TestOmitZero(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.OmitZeroAnalyzer, "omitzero/...")
}

func TestRangeInt(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.RangeIntAnalyzer, "rangeint")
}

func TestPlusBuild(t *testing.T) {
	// This test assumes a particular OS/ARCH so that the test
	// files are selected by the build; otherwise they would
	// appear in IgnoredFiles, for which file version information
	// is not available. See https://go.dev/issue/77318.
	t.Setenv("GOOS", "linux")
	t.Setenv("GOARCH", "amd64")

	// This test has a dedicated hack in the analysistest package:
	// Because it cares about IgnoredFiles, which most analyzers
	// ignore, the test framework will consider expectations in
	// ignore files too, but only for this analyzer.
	// (But see above: IgnoredFiles lack version information
	// so we can't safely apply any fixes to them.)
	RunWithSuggestedFixes(t, TestData(), goplsexport.PlusBuildModernizer, "plusbuild")
}

func TestReflectTypeFor(t *testing.T) {
	testenv.NeedsGo1Point(t, 25) // requires go1.25 types.Var.Kind
	RunWithSuggestedFixes(t, TestData(), modernize.ReflectTypeForAnalyzer, "reflecttypefor")
}

func TestSlicesContains(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.SlicesContainsAnalyzer, "slicescontains")
}

func TestSlicesDelete(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.SlicesDeleteAnalyzer, "slicesdelete")
}

func TestSlicesSort(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.SlicesSortAnalyzer, "slicessort")
}

func TestStringsBuilder(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.StringsBuilderAnalyzer, "stringsbuilder")
}

func TestStringsCut(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), goplsexport.StringsCutModernizer, "stringscut")
}

func TestStringsCutPrefix(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.StringsCutPrefixAnalyzer,
		"stringscutprefix",
		"stringscutprefix/bytescutprefix")
}

func TestStringsSeq(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.StringsSeqAnalyzer, "splitseq", "fieldsseq")
}

func TestTestingContext(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.TestingContextAnalyzer, "testingcontext")
}

func TestUnsafeFuncs(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), goplsexport.UnsafeFuncsModernizer, "unsafefuncs")
}

func TestWaitGroupGo(t *testing.T) {
	RunWithSuggestedFixes(t, TestData(), modernize.WaitGroupGoAnalyzer, "waitgroupgo")
}


================================================
FILE: go/analysis/passes/modernize/newexpr.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"slices"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/versions"
)

var NewExprAnalyzer = &analysis.Analyzer{
	Name:      "newexpr",
	Doc:       analyzerutil.MustExtractDoc(doc, "newexpr"),
	URL:       "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#newexpr",
	Requires:  []*analysis.Analyzer{inspect.Analyzer},
	Run:       run,
	FactTypes: []analysis.Fact{&newLike{}},
}

func run(pass *analysis.Pass) (any, error) {
	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info    = pass.TypesInfo
	)

	// Detect functions that are new-like, i.e. have the form:
	//
	//	func f(x T) *T { return &x }
	//
	// meaning that it is equivalent to new(x), if x has type T.
	for curFuncDecl := range inspect.Root().Preorder((*ast.FuncDecl)(nil)) {
		decl := curFuncDecl.Node().(*ast.FuncDecl)
		fn := info.Defs[decl.Name].(*types.Func)
		if decl.Body != nil && len(decl.Body.List) == 1 {
			if ret, ok := decl.Body.List[0].(*ast.ReturnStmt); ok && len(ret.Results) == 1 {
				if unary, ok := ret.Results[0].(*ast.UnaryExpr); ok && unary.Op == token.AND {
					if id, ok := unary.X.(*ast.Ident); ok {
						if v, ok := info.Uses[id].(*types.Var); ok {
							sig := fn.Signature()
							if sig.Results().Len() == 1 &&
								is[*types.Pointer](sig.Results().At(0).Type()) && // => no iface conversion
								sig.Params().Len() == 1 &&
								sig.Params().At(0) == v {

								// Export a fact for each one.
								pass.ExportObjectFact(fn, &newLike{})

								// Check file version.
								file := astutil.EnclosingFile(curFuncDecl)
								if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_26) {
									continue // new(expr) not available in this file
								}

								var edits []analysis.TextEdit

								// If 'new' is not shadowed, replace func body: &x -> new(x).
								// This makes it safely and cleanly inlinable.
								curRet, _ := curFuncDecl.FindNode(ret)
								if lookup(info, curRet, "new") == builtinNew {
									edits = []analysis.TextEdit{
										// return    &x
										//        ---- -
										// return new(x)
										{
											Pos:     unary.OpPos,
											End:     unary.OpPos + token.Pos(len("&")),
											NewText: []byte("new("),
										},
										{
											Pos:     unary.X.End(),
											End:     unary.X.End(),
											NewText: []byte(")"),
										},
									}
								}

								// Add a //go:fix inline annotation, if not already present.
								//
								// The inliner will not inline a newer callee body into an
								// older Go file; see https://go.dev/issue/75726.
								//
								// TODO(adonovan): use ast.ParseDirective when go1.26 is assured.
								if !slices.ContainsFunc(astutil.Directives(decl.Doc), func(d *astutil.Directive) bool {
									return d.Tool == "go" && d.Name == "fix" && d.Args == "inline"
								}) {
									edits = append(edits, analysis.TextEdit{
										Pos:     decl.Pos(),
										End:     decl.Pos(),
										NewText: []byte("//go:fix inline\n"),
									})
								}

								if len(edits) > 0 {
									pass.Report(analysis.Diagnostic{
										Pos:     decl.Name.Pos(),
										End:     decl.Name.End(),
										Message: fmt.Sprintf("%s can be an inlinable wrapper around new(expr)", decl.Name),
										SuggestedFixes: []analysis.SuggestedFix{
											{
												Message:   "Make %s an inlinable wrapper around new(expr)",
												TextEdits: edits,
											},
										},
									})
								}
							}
						}
					}
				}
			}
		}
	}

	// Report and transform calls, when safe.
	// In effect, this is inlining the new-like function
	// even before we have marked the callee with //go:fix inline.
	for curCall := range inspect.Root().Preorder((*ast.CallExpr)(nil)) {
		call := curCall.Node().(*ast.CallExpr)
		var fact newLike
		if fn, ok := typeutil.Callee(info, call).(*types.Func); ok &&
			pass.ImportObjectFact(fn, &fact) {

			// Check file version.
			file := astutil.EnclosingFile(curCall)
			if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_26) {
				continue // new(expr) not available in this file
			}

			// Check new is not shadowed.
			if lookup(info, curCall, "new") != builtinNew {
				continue
			}

			// The return type *T must exactly match the argument type T.
			// (We formulate it this way--not in terms of the parameter
			// type--to support generics.)
			var targ types.Type
			{
				arg := call.Args[0]
				tvarg := info.Types[arg]

				// Constants: we must work around the type checker
				// bug that causes info.Types to wrongly report the
				// "typed" type for an untyped constant.
				// (See "historical reasons" in issue go.dev/issue/70638.)
				//
				// We don't have a reliable way to do this but we can attempt
				// to re-typecheck the constant expression on its own, in
				// the original lexical environment but not as a part of some
				// larger expression that implies a conversion to some "typed" type.
				// (For the genesis of this idea see (*state).arguments
				// in ../../../../internal/refactor/inline/inline.go.)
				if tvarg.Value != nil {
					info2 := &types.Info{Types: make(map[ast.Expr]types.TypeAndValue)}
					if err := types.CheckExpr(token.NewFileSet(), pass.Pkg, token.NoPos, arg, info2); err != nil {
						continue // unexpected error
					}
					tvarg = info2.Types[arg]
				}

				targ = types.Default(tvarg.Type)
			}
			if !types.Identical(types.NewPointer(targ), info.TypeOf(call)) {
				continue
			}

			pass.Report(analysis.Diagnostic{
				Pos:     call.Pos(),
				End:     call.End(),
				Message: fmt.Sprintf("call of %s(x) can be simplified to new(x)", fn.Name()),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: fmt.Sprintf("Simplify %s(x) to new(x)", fn.Name()),
					TextEdits: []analysis.TextEdit{{
						Pos:     call.Fun.Pos(),
						End:     call.Fun.End(),
						NewText: []byte("new"),
					}},
				}},
			})
		}
	}

	return nil, nil
}

// A newLike fact records that its associated function is "new-like".
type newLike struct{}

func (*newLike) AFact()         {}
func (*newLike) String() string { return "newlike" }


================================================
FILE: go/analysis/passes/modernize/omitzero.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/types"
	"reflect"
	"strconv"
	"strings"
	"sync"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/versions"
)

var OmitZeroAnalyzer = &analysis.Analyzer{
	Name:     "omitzero",
	Doc:      analyzerutil.MustExtractDoc(doc, "omitzero"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      omitzero,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#omitzero",
}

// The omitzero pass searches for instances of "omitempty" in a json field tag on a
// struct. Since "omitfilesUsingGoVersions not have any effect when applied to a struct field,
// it suggests either deleting "omitempty" or replacing it with "omitzero", which
// correctly excludes structs from a json encoding.
func omitzero(pass *analysis.Pass) (any, error) {
	// usesKubebuilder reports whether "+kubebuilder:" appears in
	// any comment in the package, since it has its own
	// interpretation of what omitzero means; see go.dev/issue/76649.
	// It is computed once, on demand.
	usesKubebuilder := sync.OnceValue[bool](func() bool {
		for _, file := range pass.Files {
			for _, comment := range file.Comments {
				if strings.Contains(comment.Text(), "+kubebuilder:") {
					return true
				}
			}
		}
		return false
	})

	checkField := func(field *ast.Field) {
		typ := pass.TypesInfo.TypeOf(field.Type)
		_, ok := typ.Underlying().(*types.Struct)
		if !ok {
			// Not a struct
			return
		}
		tag := field.Tag
		if tag == nil {
			// No tag to check
			return
		}
		// The omitempty tag may be used by other packages besides json, but we should only modify its use with json
		tagconv, _ := strconv.Unquote(tag.Value)
		match := omitemptyRegex.FindStringSubmatchIndex(tagconv)
		if match == nil {
			// No omitempty in json tag
			return
		}
		omitEmpty, err := astutil.RangeInStringLiteral(field.Tag, match[2], match[3])
		if err != nil {
			return
		}
		var remove analysis.Range = omitEmpty

		jsonTag := reflect.StructTag(tagconv).Get("json")
		if jsonTag == ",omitempty" {
			// Remove the entire struct tag if json is the only package used
			if match[1]-match[0] == len(tagconv) {
				remove = field.Tag
			} else {
				// Remove the json tag if omitempty is the only field
				remove, err = astutil.RangeInStringLiteral(field.Tag, match[0], match[1])
				if err != nil {
					return
				}
			}
		}

		// Don't offer a fix if the package seems to use kubebuilder,
		// as it has its own intepretation of "omitzero" tags.
		// https://book.kubebuilder.io/reference/markers.html
		if usesKubebuilder() {
			return
		}

		pass.Report(analysis.Diagnostic{
			Pos:     field.Tag.Pos(),
			End:     field.Tag.End(),
			Message: "Omitempty has no effect on nested struct fields",
			SuggestedFixes: []analysis.SuggestedFix{
				{
					Message: "Remove redundant omitempty tag",
					TextEdits: []analysis.TextEdit{
						{
							Pos: remove.Pos(),
							End: remove.End(),
						},
					},
				},
				{
					Message: "Replace omitempty with omitzero (behavior change)",
					TextEdits: []analysis.TextEdit{
						{
							Pos:     omitEmpty.Pos(),
							End:     omitEmpty.End(),
							NewText: []byte(",omitzero"),
						},
					},
				},
			}})
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_24) {
		for curStruct := range curFile.Preorder((*ast.StructType)(nil)) {
			for _, curField := range curStruct.Node().(*ast.StructType).Fields.List {
				checkField(curField)
			}
		}
	}

	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/plusbuild.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/parser"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/versions"
)

var plusBuildAnalyzer = &analysis.Analyzer{
	Name: "plusbuild",
	Doc:  analyzerutil.MustExtractDoc(doc, "plusbuild"),
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#plusbuild",
	Run:  plusbuild,
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.PlusBuildModernizer = plusBuildAnalyzer
}

func plusbuild(pass *analysis.Pass) (any, error) {
	check := func(f *ast.File) {
		// "//go:build" directives were added in go1.17, but
		// we didn't start eliminating +build directives till go1.18.
		if !analyzerutil.FileUsesGoVersion(pass, f, versions.Go1_18) {
			return
		}

		// When gofmt sees a +build comment, it adds a
		// preceding equivalent //go:build directive, so in
		// formatted files we can assume that a +build line is
		// part of a comment group that starts with a
		// //go:build line and is followed by a blank line.
		//
		// While we cannot delete comments from an AST and
		// expect consistent output in general, this specific
		// case--deleting only some lines from a comment
		// block--does format correctly.
		for _, g := range f.Comments {
			sawGoBuild := false
			for _, c := range g.List {
				if sawGoBuild && strings.HasPrefix(c.Text, "// +build ") {
					pass.Report(analysis.Diagnostic{
						Pos:     c.Pos(),
						End:     c.End(),
						Message: "+build line is no longer needed",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Remove obsolete +build line",
							TextEdits: []analysis.TextEdit{{
								Pos: c.Pos(),
								End: c.End(),
							}},
						}},
					})
					break
				}
				if strings.HasPrefix(c.Text, "//go:build ") {
					sawGoBuild = true
				}
			}
		}
	}

	for _, f := range pass.Files {
		check(f)
	}
	for _, name := range pass.IgnoredFiles {
		if strings.HasSuffix(name, ".go") {
			f, err := parser.ParseFile(pass.Fset, name, nil, parser.ParseComments|parser.SkipObjectResolution)
			if err != nil {
				continue // parse error: ignore
			}
			check(f)
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/rangeint.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var RangeIntAnalyzer = &analysis.Analyzer{
	Name: "rangeint",
	Doc:  analyzerutil.MustExtractDoc(doc, "rangeint"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: rangeint,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#rangeint",
}

// rangeint offers a fix to replace a 3-clause 'for' loop:
//
//	for i := 0; i < limit; i++ {}
//
// by a range loop with an integer operand:
//
//	for i := range limit {}
//
// Variants:
//   - The ':=' may be replaced by '='.
//   - The fix may remove "i :=" if it would become unused.
//
// Restrictions:
//   - The variable i must not be assigned or address-taken within the
//     loop, because a "for range int" loop does not respect assignments
//     to the loop index.
//   - The limit must not be b.N, to avoid redundancy with bloop's fixes.
//
// Caveats:
//
// The fix causes the limit expression to be evaluated exactly once,
// instead of once per iteration. So, to avoid changing the
// cardinality of side effects, the limit expression must not involve
// function calls (e.g. seq.Len()) or channel receives. Moreover, the
// value of the limit expression must be loop invariant, which in
// practice means it must take one of the following forms:
//
//   - a local variable that is assigned only once and not address-taken;
//   - a constant; or
//   - len(s), where s has the above properties.
func rangeint(pass *analysis.Pass) (any, error) {
	var (
		info      = pass.TypesInfo
		typeindex = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	)

	for curFile := range filesUsingGoVersion(pass, versions.Go1_22) {
	nextLoop:
		for curLoop := range curFile.Preorder((*ast.ForStmt)(nil)) {
			loop := curLoop.Node().(*ast.ForStmt)
			if init, ok := loop.Init.(*ast.AssignStmt); ok &&
				isSimpleAssign(init) &&
				is[*ast.Ident](init.Lhs[0]) &&
				isZeroIntConst(info, init.Rhs[0]) {
				// Have: for i = 0; ... (or i := 0)
				index := init.Lhs[0].(*ast.Ident)

				if compare, ok := loop.Cond.(*ast.BinaryExpr); ok &&
					compare.Op == token.LSS &&
					astutil.EqualSyntax(compare.X, init.Lhs[0]) {
					// Have: for i = 0; i < limit; ... {}

					limit := compare.Y

					// If limit is "len(slice)", simplify it to "slice".
					//
					// (Don't replace "for i := 0; i < len(map); i++"
					// with "for range m" because it's too hard to prove
					// that len(m) is loop-invariant).
					if call, ok := limit.(*ast.CallExpr); ok &&
						typeutil.Callee(info, call) == builtinLen &&
						is[*types.Slice](info.TypeOf(call.Args[0]).Underlying()) {
						limit = call.Args[0]
					}

					// Check the form of limit: must be a constant,
					// or a local var that is not assigned or address-taken.
					limitOK := false
					if info.Types[limit].Value != nil {
						limitOK = true // constant
					} else if id, ok := limit.(*ast.Ident); ok {
						if v, ok := info.Uses[id].(*types.Var); ok &&
							!(v.Exported() && typesinternal.IsPackageLevel(v)) {
							// limit is a local or unexported global var.
							// (An exported global may have uses we can't see.)
							for cur := range typeindex.Uses(v) {
								if isScalarLvalue(info, cur) {
									// Limit var is assigned or address-taken.
									continue nextLoop
								}
							}
							limitOK = true
						}
					}
					if !limitOK {
						continue nextLoop
					}

					validIncrement := false
					if inc, ok := loop.Post.(*ast.IncDecStmt); ok &&
						inc.Tok == token.INC &&
						astutil.EqualSyntax(compare.X, inc.X) {
						// Have: i++
						validIncrement = true
					} else if assign, ok := loop.Post.(*ast.AssignStmt); ok &&
						assign.Tok == token.ADD_ASSIGN &&
						len(assign.Rhs) == 1 && isIntLiteral(info, assign.Rhs[0], 1) &&
						len(assign.Lhs) == 1 && astutil.EqualSyntax(compare.X, assign.Lhs[0]) {
						// Have: i += 1
						validIncrement = true
					}

					if validIncrement {
						// Have: for i = 0; i < limit; i++ {}

						// Find references to i within the loop body.
						v := info.ObjectOf(index).(*types.Var)
						switch v.Kind() {
						case types.PackageVar:
							continue nextLoop
						case types.ResultVar:
							// If v is a named result, it is implicitly
							// used after the loop (go.dev/issue/76880).
							continue nextLoop
						}

						used := false
						for curId := range curLoop.Child(loop.Body).Preorder((*ast.Ident)(nil)) {
							id := curId.Node().(*ast.Ident)
							if info.Uses[id] == v {
								used = true

								// Reject if any is an l-value (assigned or address-taken):
								// a "for range int" loop does not respect assignments to
								// the loop variable.
								if isScalarLvalue(info, curId) {
									continue nextLoop
								}
							}
						}

						// If i is no longer used, delete "i := ".
						var edits []analysis.TextEdit
						if !used && init.Tok == token.DEFINE {
							edits = append(edits, analysis.TextEdit{
								Pos: index.Pos(),
								End: init.Rhs[0].Pos(),
							})
						}

						// If i is used after the loop,
						// don't offer a fix, as a range loop
						// leaves i with a different final value (limit-1).
						if init.Tok == token.ASSIGN {
							// Find the nearest ancestor that is not a label.
							// Otherwise, checking for i usage outside of a for
							// loop might not function properly further below.
							// This is because the i usage might be a child of
							// the loop's parent's parent, for example:
							//     var i int
							// Loop:
							//     for i = 0; i < 10; i++ { break loop }
							//     // i is in the sibling of the label, not the loop
							//     fmt.Println(i)
							//
							ancestor := curLoop.Parent()
							for is[*ast.LabeledStmt](ancestor.Node()) {
								ancestor = ancestor.Parent()
							}
							for curId := range ancestor.Preorder((*ast.Ident)(nil)) {
								id := curId.Node().(*ast.Ident)
								if info.Uses[id] == v {
									// Is i used after loop?
									if id.Pos() > loop.End() {
										continue nextLoop
									}
									// Is i used within a defer statement
									// that is within the scope of i?
									//     var i int
									//     defer func() { print(i)}
									//     for i = ... { ... }
									for curDefer := range curId.Enclosing((*ast.DeferStmt)(nil)) {
										if curDefer.Node().Pos() > v.Pos() {
											continue nextLoop
										}
									}
								}
							}
						}

						// If limit is len(slice),
						// simplify "range len(slice)" to "range slice".
						if call, ok := limit.(*ast.CallExpr); ok &&
							typeutil.Callee(info, call) == builtinLen &&
							is[*types.Slice](info.TypeOf(call.Args[0]).Underlying()) {
							limit = call.Args[0]
						}

						// If the limit is a untyped constant of non-integer type,
						// such as "const limit = 1e3", its effective type may
						// differ between the two forms.
						// In a for loop, it must be comparable with int i,
						//    for i := 0; i < limit; i++ {}
						// but in a range loop it would become a float,
						//    for i := range limit {}
						// which is a type error. We need to convert it to int
						// in this case.
						//
						// Unfortunately go/types discards the untyped type
						// (but see Untyped in golang/go#70638) so we must
						// re-type check the expression to detect this case.
						var beforeLimit, afterLimit string
						if v := info.Types[limit].Value; v != nil {
							tVar := info.TypeOf(init.Rhs[0])
							file := curFile.Node().(*ast.File)
							// TODO(mkalil): use a types.Qualifier that respects the existing
							// imports of this file that are visible (not shadowed) at the current position.
							qual := typesinternal.FileQualifier(file, pass.Pkg)
							beforeLimit, afterLimit = fmt.Sprintf("%s(", types.TypeString(tVar, qual)), ")"
							info2 := &types.Info{Types: make(map[ast.Expr]types.TypeAndValue)}
							if types.CheckExpr(pass.Fset, pass.Pkg, limit.Pos(), limit, info2) == nil {
								tLimit := info2.TypeOf(limit)
								// Eliminate conversion when safe.
								//
								// Redundant conversions are not only unsightly but may in some cases cause
								// architecture-specific types (e.g. syscall.Timespec.Nsec) to be inserted
								// into otherwise portable files.
								//
								// The operand must have an integer type (not, say, '1e6')
								// even when assigning to an existing integer variable.
								if isInteger(tLimit) {
									// When declaring a new var from an untyped limit,
									// the limit's default type is what matters.
									if init.Tok != token.ASSIGN {
										tLimit = types.Default(tLimit)
									}
									if types.AssignableTo(tLimit, tVar) {
										beforeLimit, afterLimit = "", ""
									}
								}
							}
						}

						pass.Report(analysis.Diagnostic{
							Pos:     init.Pos(),
							End:     loop.Post.End(),
							Message: "for loop can be modernized using range over int",
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: fmt.Sprintf("Replace for loop with range %s",
									astutil.Format(pass.Fset, limit)),
								TextEdits: append(edits, []analysis.TextEdit{
									// for i := 0; i < limit; i++ {}
									//     -----              ---
									//          -------
									// for i := range  limit      {}

									// Delete init.
									{
										Pos:     init.Rhs[0].Pos(),
										End:     limit.Pos(),
										NewText: []byte("range "),
									},
									// Add "int(" before limit, if needed.
									{
										Pos:     limit.Pos(),
										End:     limit.Pos(),
										NewText: []byte(beforeLimit),
									},
									// Delete inc.
									{
										Pos: limit.End(),
										End: loop.Post.End(),
									},
									// Add ")" after limit, if needed.
									{
										Pos:     limit.End(),
										End:     limit.End(),
										NewText: []byte(afterLimit),
									},
								}...),
							}},
						})
					}
				}
			}
		}
	}
	return nil, nil
}

// isScalarLvalue reports whether the specified identifier is
// address-taken or appears on the left side of an assignment.
//
// This function is valid only for scalars (x = ...),
// not for aggregates (x.a[i] = ...)
func isScalarLvalue(info *types.Info, curId inspector.Cursor) bool {
	// Unfortunately we can't simply use info.Types[e].Assignable()
	// as it is always true for a variable even when that variable is
	// used only as an r-value. So we must inspect enclosing syntax.

	cur := curId

	// Strip enclosing parens.
	ek := cur.ParentEdgeKind()
	for ek == edge.ParenExpr_X {
		cur = cur.Parent()
		ek = cur.ParentEdgeKind()
	}

	switch ek {
	case edge.AssignStmt_Lhs:
		assign := cur.Parent().Node().(*ast.AssignStmt)
		if assign.Tok != token.DEFINE {
			return true // i = j or i += j
		}
		id := curId.Node().(*ast.Ident)
		if v, ok := info.Defs[id]; ok && v.Pos() != id.Pos() {
			return true // reassignment of i (i, j := 1, 2)
		}
	case edge.RangeStmt_Key:
		rng := cur.Parent().Node().(*ast.RangeStmt)
		if rng.Tok == token.ASSIGN {
			return true // "for k, v = range x" is like an AssignStmt to k, v
		}
	case edge.IncDecStmt_X:
		return true // i++, i--
	case edge.UnaryExpr_X:
		if cur.Parent().Node().(*ast.UnaryExpr).Op == token.AND {
			return true // &i
		}
	}
	return false
}

// enclosingSignature returns the signature of the innermost
// function enclosing the syntax node denoted by cur
// or nil if the node is not within a function.
//
// TODO(adonovan): factor with gopls/internal/util/typesutil.EnclosingSignature.
func enclosingSignature(cur inspector.Cursor, info *types.Info) *types.Signature {
	if c, ok := enclosingFunc(cur); ok {
		switch n := c.Node().(type) {
		case *ast.FuncDecl:
			if f, ok := info.Defs[n.Name]; ok {
				return f.Type().(*types.Signature)
			}
		case *ast.FuncLit:
			if f, ok := info.Types[n]; ok {
				return f.Type.(*types.Signature)
			}
		}
	}
	return nil
}


================================================
FILE: go/analysis/passes/modernize/reflect.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

// This file defines modernizers that use the "reflect" package.

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var ReflectTypeForAnalyzer = &analysis.Analyzer{
	Name: "reflecttypefor",
	Doc:  analyzerutil.MustExtractDoc(doc, "reflecttypefor"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: reflecttypefor,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#reflecttypefor",
}

func reflecttypefor(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo

		reflectTypeOf = index.Object("reflect", "TypeOf")
	)

	for curCall := range index.Calls(reflectTypeOf) {
		call := curCall.Node().(*ast.CallExpr)
		// Have: reflect.TypeOf(expr)

		expr := call.Args[0]

		// reflect.TypeFor cannot be instantiated with an untyped nil.
		// We use type information rather than checking the identifier name
		// to correctly handle edge cases where "nil" is shadowed (e.g. nil := "nil").
		if info.Types[expr].IsNil() {
			continue
		}

		if !typesinternal.NoEffects(info, expr) {
			continue // don't eliminate operand: may have effects
		}

		t := info.TypeOf(expr)
		var edits []analysis.TextEdit

		// Special cases for TypeOf((*T)(nil)).Elem(), and
		// TypeOf([]T(nil)).Elem(), needed when T is an interface type.
		if curCall.ParentEdgeKind() == edge.SelectorExpr_X {
			curSel := unparenEnclosing(curCall).Parent()
			if curSel.ParentEdgeKind() == edge.CallExpr_Fun {
				call2 := unparenEnclosing(curSel).Parent().Node().(*ast.CallExpr) // potentially .Elem()
				obj := typeutil.Callee(info, call2)
				if typesinternal.IsMethodNamed(obj, "reflect", "Type", "Elem") {
					// reflect.TypeOf(expr).Elem()
					//                     -------
					// reflect.TypeOf(expr)
					if typ, hasElem := t.(interface{ Elem() types.Type }); hasElem {
						// Have: TypeOf(expr).Elem() where expr is *T, []T, [k]T, chan T, map[K]T, etc.
						t = typ.Elem()
						edits = []analysis.TextEdit{{
							Pos: call.End(),
							End: call2.End(),
						}}
					}
				}
			}
		}

		// TypeOf(x) where x has an interface type is a
		// dynamic operation; don't transform it to TypeFor.
		// (edits == nil means "not the Elem() special case".)
		if types.IsInterface(t) && edits == nil {
			continue
		}

		file := astutil.EnclosingFile(curCall)
		if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_22) {
			continue // TypeFor requires go1.22
		}
		tokFile := pass.Fset.File(file.Pos())

		// Format the type as valid Go syntax.
		// TODO(adonovan): FileQualifier needs to respect
		// visibility at the current point, and either fail
		// or edit the imports as needed.
		qual := typesinternal.FileQualifier(file, pass.Pkg)
		tstr := types.TypeString(t, qual)

		sel, ok := call.Fun.(*ast.SelectorExpr)
		if !ok {
			continue // e.g. reflect was dot-imported
		}

		// Don't offer a fix if the type contains an unnamed struct or unnamed
		// interface because the replacement would be significantly more verbose.
		// (See golang/go#76698)
		if isComplicatedType(t) {
			continue
		}

		// Don't offer the fix if the type string is too long. We define "too
		// long" as more than three times the length of the original expression
		// and at least 16 characters (a 3x length increase of a very
		// short expression should not be cause for skipping the fix).
		oldLen := int(expr.End() - expr.Pos())
		newLen := len(tstr)
		if newLen >= 16 && newLen > 3*oldLen {
			continue
		}

		// If the call argument contains the last use
		// of a variable, as in:
		//	var zero T
		//	reflect.TypeOf(zero)
		// remove the declaration of that variable.
		curArg0 := curCall.ChildAt(edge.CallExpr_Args, 0)
		edits = append(edits, refactor.DeleteUnusedVars(index, info, tokFile, curArg0)...)

		pass.Report(analysis.Diagnostic{
			Pos:     call.Fun.Pos(),
			End:     call.Fun.End(),
			Message: "reflect.TypeOf call can be simplified using TypeFor",
			SuggestedFixes: []analysis.SuggestedFix{{
				// reflect.TypeOf    (...T value...)
				//         ------     -------------
				// reflect.TypeFor[T](             )
				Message: "Replace TypeOf by TypeFor",
				TextEdits: append([]analysis.TextEdit{
					{
						Pos:     sel.Sel.Pos(),
						End:     sel.Sel.End(),
						NewText: []byte("TypeFor[" + tstr + "]"),
					},
					// delete (pure) argument
					{
						Pos: call.Lparen + 1,
						End: call.Rparen,
					},
				}, edits...),
			}},
		})
	}

	return nil, nil
}

// isComplicatedType reports whether type t is complicated, e.g. it is or contains an
// unnamed struct, interface, or function signature.
func isComplicatedType(t types.Type) bool {
	var check func(typ types.Type) bool
	check = func(typ types.Type) bool {
		switch t := typ.(type) {
		case typesinternal.NamedOrAlias:
			for ta := range t.TypeArgs().Types() {
				if check(ta) {
					return true
				}
			}
			return false
		case *types.Struct, *types.Interface, *types.Signature:
			// These are complex types with potentially many elements
			// so we should avoid duplicating their definition.
			return true
		case *types.Pointer:
			return check(t.Elem())
		case *types.Slice:
			return check(t.Elem())
		case *types.Array:
			return check(t.Elem())
		case *types.Chan:
			return check(t.Elem())
		case *types.Map:
			return check(t.Key()) || check(t.Elem())
		case *types.Basic:
			return false
		case *types.TypeParam:
			return false
		default:
			// Includes types.Union
			return true
		}
	}

	return check(t)
}


================================================
FILE: go/analysis/passes/modernize/slices.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/types"
	"slices"
	"strconv"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

// Warning: this analyzer is not safe to enable by default.
var AppendClippedAnalyzer = &analysis.Analyzer{
	Name:     "appendclipped",
	Doc:      analyzerutil.MustExtractDoc(doc, "appendclipped"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      appendclipped,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#appendclipped",
}

// The appendclipped pass offers to simplify a tower of append calls:
//
//	append(append(append(base, a...), b..., c...)
//
// with a call to go1.21's slices.Concat(base, a, b, c), or simpler
// replacements such as slices.Clone(a) in degenerate cases.
//
// We offer bytes.Clone in preference to slices.Clone where
// appropriate, if the package already imports "bytes";
// their behaviors are identical.
//
// The base expression must denote a clipped slice (see [isClipped]
// for definition), otherwise the replacement might eliminate intended
// side effects to the base slice's array.
//
// Examples:
//
//	append(append(append(x[:0:0], a...), b...), c...) -> slices.Concat(a, b, c)
//	append(append(slices.Clip(a), b...)               -> slices.Concat(a, b)
//	append([]T{}, a...)                               -> slices.Clone(a)
//	append([]string(nil), os.Environ()...)            -> os.Environ()
//
// The fix does not always preserve nilness the of base slice when the
// addends (a, b, c) are all empty (see #73557).
func appendclipped(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "bytes", "runtime") {
		return nil, nil
	}

	info := pass.TypesInfo

	// sliceArgs is a non-empty (reversed) list of slices to be concatenated.
	simplifyAppendEllipsis := func(file *ast.File, call *ast.CallExpr, base ast.Expr, sliceArgs []ast.Expr) {
		// Only appends whose base is a clipped slice can be simplified:
		// We must conservatively assume an append to an unclipped slice
		// such as append(y[:0], x...) is intended to have effects on y.
		clipped, empty := clippedSlice(info, base)
		if clipped == nil {
			return
		}

		// If any slice arg has a different type from the base
		// (and thus the result) don't offer a fix, to avoid
		// changing the return type, e.g:
		//
		//     type S []int
		//   - x := append([]int(nil), S{}...) // x : []int
		//   + x := slices.Clone(S{})          // x : S
		//
		// We could do better by inserting an explicit generic
		// instantiation:
		//
		//   x := slices.Clone[[]int](S{})
		//
		// but this is often unnecessary and unwanted, such as
		// when the value is used an in assignment context that
		// provides an explicit type:
		//
		//   var x []int = slices.Clone(S{})
		baseType := info.TypeOf(base)
		for _, arg := range sliceArgs {
			if !types.Identical(info.TypeOf(arg), baseType) {
				return
			}
		}

		// If the (clipped) base is empty, it may be safely ignored.
		// Otherwise treat it (or its unclipped subexpression, if possible)
		// as just another arg (the first) to Concat.
		//
		// TODO(adonovan): not so fast! If all the operands
		// are empty, then the nilness of base matters, because
		// append preserves nilness whereas Concat does not (#73557).
		if !empty {
			sliceArgs = append(sliceArgs, clipped)
		}
		slices.Reverse(sliceArgs)

		// TODO(adonovan): simplify sliceArgs[0] further: slices.Clone(s) -> s

		// Concat of a single (non-trivial) slice degenerates to Clone.
		if len(sliceArgs) == 1 {
			s := sliceArgs[0]

			// Special case for common but redundant clone of os.Environ().
			// append(zerocap, os.Environ()...) -> os.Environ()
			if scall, ok := s.(*ast.CallExpr); ok {
				obj := typeutil.Callee(info, scall)
				if typesinternal.IsFunctionNamed(obj, "os", "Environ") {
					pass.Report(analysis.Diagnostic{
						Pos:     call.Pos(),
						End:     call.End(),
						Message: "Redundant clone of os.Environ()",
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Eliminate redundant clone",
							TextEdits: []analysis.TextEdit{{
								Pos:     call.Pos(),
								End:     call.End(),
								NewText: []byte(astutil.Format(pass.Fset, s)),
							}},
						}},
					})
					return
				}
			}

			// If the slice type is []byte, and the file imports
			// "bytes" but not "slices", prefer the (behaviorally
			// identical) bytes.Clone for local consistency.
			// https://go.dev/issue/70815#issuecomment-2671572984
			fileImports := func(path string) bool {
				return slices.ContainsFunc(file.Imports, func(spec *ast.ImportSpec) bool {
					return first(strconv.Unquote(spec.Path.Value)) == path
				})
			}
			clonepkg := cond(
				types.Identical(info.TypeOf(call), byteSliceType) &&
					!fileImports("slices") && fileImports("bytes"),
				"bytes",
				"slices")

			// append(zerocap, s...) -> slices.Clone(s) or bytes.Clone(s)
			//
			// This is unsound if s is empty and its nilness
			// differs from zerocap (#73557).
			prefix, importEdits := refactor.AddImport(info, file, clonepkg, clonepkg, "Clone", call.Pos())
			message := fmt.Sprintf("Replace append with %s.Clone", clonepkg)
			pass.Report(analysis.Diagnostic{
				Pos:     call.Pos(),
				End:     call.End(),
				Message: message,
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: message,
					TextEdits: append(importEdits, []analysis.TextEdit{{
						Pos:     call.Pos(),
						End:     call.End(),
						NewText: fmt.Appendf(nil, "%sClone(%s)", prefix, astutil.Format(pass.Fset, s)),
					}}...),
				}},
			})
			return
		}

		// append(append(append(base, a...), b..., c...) -> slices.Concat(base, a, b, c)
		//
		// This is unsound if all slices are empty and base is non-nil (#73557).
		prefix, importEdits := refactor.AddImport(info, file, "slices", "slices", "Concat", call.Pos())
		pass.Report(analysis.Diagnostic{
			Pos:     call.Pos(),
			End:     call.End(),
			Message: "Replace append with slices.Concat",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Replace append with slices.Concat",
				TextEdits: append(importEdits, []analysis.TextEdit{{
					Pos:     call.Pos(),
					End:     call.End(),
					NewText: fmt.Appendf(nil, "%sConcat(%s)", prefix, formatExprs(pass.Fset, sliceArgs)),
				}}...),
			}},
		})
	}

	// Mark nested calls to append so that we don't emit diagnostics for them.
	skip := make(map[*ast.CallExpr]bool)

	// Visit calls of form append(x, y...).
	for curFile := range filesUsingGoVersion(pass, versions.Go1_21) {
		file := curFile.Node().(*ast.File)

		for curCall := range curFile.Preorder((*ast.CallExpr)(nil)) {
			call := curCall.Node().(*ast.CallExpr)
			if skip[call] {
				continue
			}

			// Recursively unwrap ellipsis calls to append, so
			//   append(append(append(base, a...), b..., c...)
			// yields (base, [c b a]).
			base, slices := ast.Expr(call), []ast.Expr(nil) // base case: (call, nil)
		again:
			if call, ok := base.(*ast.CallExpr); ok {
				if id, ok := call.Fun.(*ast.Ident); ok &&
					call.Ellipsis.IsValid() &&
					len(call.Args) == 2 &&
					info.Uses[id] == builtinAppend {

					// Have: append(base, s...)
					base, slices = call.Args[0], append(slices, call.Args[1])
					skip[call] = true
					goto again
				}
			}

			if len(slices) > 0 {
				simplifyAppendEllipsis(file, call, base, slices)
			}
		}
	}
	return nil, nil
}

// clippedSlice returns res != nil if e denotes a slice that is
// definitely clipped, that is, its len(s)==cap(s).
//
// The value of res is either the same as e or is a subexpression of e
// that denotes the same slice but without the clipping operation.
//
// In addition, it reports whether the slice is definitely empty.
//
// Examples of clipped slices:
//
//	x[:0:0]				(empty)
//	[]T(nil)			(empty)
//	Slice{}				(empty)
//	x[:len(x):len(x)]		(nonempty)  res=x
//	x[:k:k]	 	         	(nonempty)
//	slices.Clip(x)			(nonempty)  res=x
//
// TODO(adonovan): Add a check that the expression x has no side effects in
// case x[:len(x):len(x)] -> x. Now the program behavior may change.
func clippedSlice(info *types.Info, e ast.Expr) (res ast.Expr, empty bool) {
	switch e := e.(type) {
	case *ast.SliceExpr:
		// x[:0:0], x[:len(x):len(x)], x[:k:k]
		if e.Slice3 && e.High != nil && e.Max != nil && astutil.EqualSyntax(e.High, e.Max) { // x[:k:k]
			res = e
			empty = isZeroIntConst(info, e.High) // x[:0:0]
			if call, ok := e.High.(*ast.CallExpr); ok &&
				typeutil.Callee(info, call) == builtinLen &&
				astutil.EqualSyntax(call.Args[0], e.X) {
				res = e.X // x[:len(x):len(x)] -> x
			}
			return
		}
		return

	case *ast.CallExpr:
		// []T(nil)?
		if info.Types[e.Fun].IsType() &&
			is[*ast.Ident](e.Args[0]) &&
			info.Uses[e.Args[0].(*ast.Ident)] == builtinNil {
			return e, true
		}

		// slices.Clip(x)?
		obj := typeutil.Callee(info, e)
		if typesinternal.IsFunctionNamed(obj, "slices", "Clip") {
			return e.Args[0], false // slices.Clip(x) -> x
		}

	case *ast.CompositeLit:
		// Slice{}?
		if len(e.Elts) == 0 {
			return e, true
		}
	}
	return nil, false
}


================================================
FILE: go/analysis/passes/modernize/slicescontains.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var SlicesContainsAnalyzer = &analysis.Analyzer{
	Name: "slicescontains",
	Doc:  analyzerutil.MustExtractDoc(doc, "slicescontains"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: slicescontains,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicescontains",
}

// The slicescontains pass identifies loops that can be replaced by a
// call to slices.Contains{,Func}. For example:
//
//	for i, elem := range s {
//		if elem == needle {
//			...
//			break
//		}
//	}
//
// =>
//
//	if slices.Contains(s, needle) { ... }
//
// Variants:
//   - if the if-condition is f(elem), the replacement
//     uses slices.ContainsFunc(s, f).
//   - if the if-body is "return true" and the fallthrough
//     statement is "return false" (or vice versa), the
//     loop becomes "return [!]slices.Contains(...)".
//   - if the if-body is "found = true" and the previous
//     statement is "found = false" (or vice versa), the
//     loop becomes "found = [!]slices.Contains(...)".
//
// It may change cardinality of effects of the "needle" expression.
// (Mostly this appears to be a desirable optimization, avoiding
// redundantly repeated evaluation.)
//
// TODO(adonovan): Add a check that needle/predicate expression from
// if-statement has no effects. Now the program behavior may change.
func slicescontains(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "runtime") {
		return nil, nil
	}

	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	// check is called for each RangeStmt of this form:
	//   for i, elem := range s { if cond { ... } }
	check := func(file *ast.File, curRange inspector.Cursor) {
		rng := curRange.Node().(*ast.RangeStmt)
		ifStmt := rng.Body.List[0].(*ast.IfStmt)

		// isSliceElem reports whether e denotes the
		// current slice element (elem or s[i]).
		isSliceElem := func(e ast.Expr) bool {
			if rng.Value != nil && astutil.EqualSyntax(e, rng.Value) {
				return true // "elem"
			}
			if x, ok := e.(*ast.IndexExpr); ok &&
				astutil.EqualSyntax(x.X, rng.X) &&
				astutil.EqualSyntax(x.Index, rng.Key) {
				return true // "s[i]"
			}
			return false
		}

		// Examine the condition for one of these forms:
		//
		// - if elem or s[i] == needle  { ... } => Contains
		// - if predicate(s[i] or elem) { ... } => ContainsFunc
		var (
			funcName string   // "Contains" or "ContainsFunc"
			arg2     ast.Expr // second argument to func (needle or predicate)
		)
		switch cond := ifStmt.Cond.(type) {
		case *ast.BinaryExpr:
			if cond.Op == token.EQL {
				var elem ast.Expr
				if isSliceElem(cond.X) {
					funcName = "Contains"
					elem = cond.X
					arg2 = cond.Y // "if elem == needle"
				} else if isSliceElem(cond.Y) {
					funcName = "Contains"
					elem = cond.Y
					arg2 = cond.X // "if needle == elem"
				}

				// Reject if elem and needle have different types.
				if elem != nil {
					tElem := info.TypeOf(elem)
					tNeedle := info.TypeOf(arg2)
					if !types.Identical(tElem, tNeedle) {
						// Avoid ill-typed slices.Contains([]error, any).
						if !types.AssignableTo(tNeedle, tElem) {
							return
						}
						// TODO(adonovan): relax this check to allow
						//   slices.Contains([]error, error(any)),
						// inserting an explicit widening conversion
						// around the needle.
						return
					}
				}
			}

		case *ast.CallExpr:
			if len(cond.Args) == 1 &&
				isSliceElem(cond.Args[0]) &&
				typeutil.Callee(info, cond) != nil { // not a conversion

				// Attempt to get signature
				sig, isSignature := info.TypeOf(cond.Fun).(*types.Signature)
				if isSignature {
					// skip variadic functions
					if sig.Variadic() {
						return
					}

					// Slice element type must match function parameter type.
					var (
						tElem  = typeparams.CoreType(info.TypeOf(rng.X)).(*types.Slice).Elem()
						tParam = sig.Params().At(0).Type()
					)
					if !types.Identical(tElem, tParam) {
						return
					}
				}

				funcName = "ContainsFunc"
				arg2 = cond.Fun // "if predicate(elem)"
			}
		}
		if funcName == "" {
			return // not a candidate for Contains{,Func}
		}

		// body is the "true" body.
		body := ifStmt.Body
		if len(body.List) == 0 {
			// (We could perhaps delete the loop entirely.)
			return
		}

		// Reject if the body, needle or predicate references either range variable.
		usesRangeVar := func(n ast.Node) bool {
			cur, ok := curRange.FindNode(n)
			if !ok {
				panic(fmt.Sprintf("FindNode(%T) failed", n))
			}
			return uses(index, cur, info.Defs[rng.Key.(*ast.Ident)]) ||
				rng.Value != nil && uses(index, cur, info.Defs[rng.Value.(*ast.Ident)])
		}
		if usesRangeVar(body) {
			// Body uses range var "i" or "elem".
			//
			// (The check for "i" could be relaxed when we
			// generalize this to support slices.Index;
			// and the check for "elem" could be relaxed
			// if "elem" can safely be replaced in the
			// body by "needle".)
			return
		}
		if usesRangeVar(arg2) {
			return
		}

		// Prepare slices.Contains{,Func} call.
		prefix, importEdits := refactor.AddImport(info, file, "slices", "slices", funcName, rng.Pos())
		contains := fmt.Sprintf("%s%s(%s, %s)",
			prefix,
			funcName,
			astutil.Format(pass.Fset, rng.X),
			astutil.Format(pass.Fset, arg2))

		report := func(edits []analysis.TextEdit) {
			pass.Report(analysis.Diagnostic{
				Pos:     rng.Pos(),
				End:     rng.End(),
				Message: fmt.Sprintf("Loop can be simplified using slices.%s", funcName),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   "Replace loop by call to slices." + funcName,
					TextEdits: append(edits, importEdits...),
				}},
			})
		}

		// Last statement of body must return/break out of the loop.
		//
		// TODO(adonovan): opt:consider avoiding FindNode with new API of form:
		//    curRange.Get(edge.RangeStmt_Body, -1).
		//             Get(edge.BodyStmt_List, 0).
		//             Get(edge.IfStmt_Body)
		curBody, _ := curRange.FindNode(body)
		curLastStmt, _ := curBody.LastChild()

		// Reject if any statement in the body except the
		// last has a free continuation (continue or break)
		// that might affected by melting down the loop.
		//
		// TODO(adonovan): relax check by analyzing branch target.
		numBodyStmts := 0
		for curBodyStmt := range curBody.Children() {
			numBodyStmts += 1
			if curBodyStmt != curLastStmt {
				for range curBodyStmt.Preorder((*ast.BranchStmt)(nil), (*ast.ReturnStmt)(nil)) {
					return
				}
			}
		}

		switch lastStmt := curLastStmt.Node().(type) {
		case *ast.ReturnStmt:
			// Have: for ... range seq { if ... { stmts; return x } }

			// Special case:
			// body={ return true } next="return false"   (or negation)
			// => return [!]slices.Contains(...)
			if curNext, ok := curRange.NextSibling(); ok {
				nextStmt := curNext.Node().(ast.Stmt)
				tval := isReturnTrueOrFalse(info, lastStmt)
				fval := isReturnTrueOrFalse(info, nextStmt)
				if len(body.List) == 1 && tval*fval < 0 {
					//    for ... { if ... { return true/false } }
					// => return [!]slices.Contains(...)
					report([]analysis.TextEdit{
						// Delete the range statement and following space.
						{
							Pos: rng.Pos(),
							End: nextStmt.Pos(),
						},
						// Change return to [!]slices.Contains(...).
						{
							Pos: nextStmt.Pos(),
							End: nextStmt.End(),
							NewText: fmt.Appendf(nil, "return %s%s",
								cond(tval > 0, "", "!"),
								contains),
						},
					})
					return
				}
			}

			// General case:
			// => if slices.Contains(...) { stmts; return x }
			report([]analysis.TextEdit{
				// Replace "for ... { if ... " with "if slices.Contains(...)".
				{
					Pos:     rng.Pos(),
					End:     ifStmt.Body.Pos(),
					NewText: fmt.Appendf(nil, "if %s ", contains),
				},
				// Delete '}' of range statement and preceding space.
				{
					Pos: ifStmt.Body.End(),
					End: rng.End(),
				},
			})
			return

		case *ast.BranchStmt:
			if lastStmt.Tok == token.BREAK && lastStmt.Label == nil { // unlabeled break
				// Have: for ... { if ... { stmts; break } }
				if numBodyStmts == 1 {
					// If the only stmt in the body is an unlabeled "break" that
					// will get deleted in the fix, don't suggest a fix, as it
					// produces confusing code:
					//    if slices.Contains(slice, f) {}
					// Explicitly discarding the result isn't much better:
					//    _ = slices.Contains(slice, f) // just for effects
					// See https://go.dev/issue/77677.
					return
				}
				var prevStmt ast.Stmt // previous statement to range (if any)
				if curPrev, ok := curRange.PrevSibling(); ok {
					// If the RangeStmt's previous sibling is a Stmt,
					// the RangeStmt must be among the Body list of
					// a BlockStmt, CauseClause, or CommClause.
					// In all cases, the prevStmt is the immediate
					// predecessor of the RangeStmt during execution.
					//
					// (This is not true for Stmts in general;
					// see [Cursor.Children] and #71074.)
					prevStmt, _ = curPrev.Node().(ast.Stmt)
				}

				// Special case:
				// prev="lhs = false" body={ lhs = true; break }
				// => lhs = slices.Contains(...) (or its negation)
				if assign, ok := body.List[0].(*ast.AssignStmt); ok &&
					len(body.List) == 2 &&
					assign.Tok == token.ASSIGN &&
					len(assign.Lhs) == 1 &&
					len(assign.Rhs) == 1 {

					// Have: body={ lhs = rhs; break }
					assignBool := isTrueOrFalse(info, assign.Rhs[0])
					if prevAssign, ok := prevStmt.(*ast.AssignStmt); ok &&
						len(prevAssign.Lhs) == 1 &&
						len(prevAssign.Rhs) == 1 &&
						assignBool != 0 && // non-bool assignments don't apply in this case
						astutil.EqualSyntax(prevAssign.Lhs[0], assign.Lhs[0]) &&
						assignBool == -isTrueOrFalse(info, prevAssign.Rhs[0]) {

						// Have:
						//    lhs = false
						//    for ... { if ... { lhs = true; break } }
						//  =>
						//    lhs = slices.Contains(...)
						//
						// TODO(adonovan):
						// - support "var lhs bool = false" and variants.
						// - allow the break to be omitted.
						neg := cond(assignBool < 0, "!", "")
						report([]analysis.TextEdit{
							// Replace "rhs" of previous assignment by [!]slices.Contains(...)
							{
								Pos:     prevAssign.Rhs[0].Pos(),
								End:     prevAssign.Rhs[0].End(),
								NewText: []byte(neg + contains),
							},
							// Delete the loop and preceding space.
							{
								Pos: prevAssign.Rhs[0].End(),
								End: rng.End(),
							},
						})
						return
					}
				}

				// General case:
				//    for ... { if ...        { stmts; break } }
				// => if slices.Contains(...) { stmts        }
				report([]analysis.TextEdit{
					// Replace "for ... { if ... " with "if slices.Contains(...)".
					{
						Pos:     rng.Pos(),
						End:     ifStmt.Body.Pos(),
						NewText: fmt.Appendf(nil, "if %s ", contains),
					},
					// Delete break statement and preceding space.
					{
						Pos: func() token.Pos {
							if len(body.List) > 1 {
								beforeBreak, _ := curLastStmt.PrevSibling()
								return beforeBreak.Node().End()
							}
							return lastStmt.Pos()
						}(),
						End: lastStmt.End(),
					},
					// Delete '}' of range statement and preceding space.
					{
						Pos: ifStmt.Body.End(),
						End: rng.End(),
					},
				})
				return
			}
		}
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_21) {
		file := curFile.Node().(*ast.File)

		for curRange := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			rng := curRange.Node().(*ast.RangeStmt)

			if is[*ast.Ident](rng.Key) &&
				rng.Tok == token.DEFINE &&
				len(rng.Body.List) == 1 &&
				is[*types.Slice](typeparams.CoreType(info.TypeOf(rng.X))) {

				// Have:
				// - for _, elem := range s { S }
				// - for i       := range s { S }

				if ifStmt, ok := rng.Body.List[0].(*ast.IfStmt); ok &&
					ifStmt.Init == nil && ifStmt.Else == nil {

					// Have: for i, elem := range s { if cond { ... } }
					check(file, curRange)
				}
			}
		}
	}
	return nil, nil
}

// -- helpers --

// isReturnTrueOrFalse returns nonzero if stmt returns true (+1) or false (-1).
func isReturnTrueOrFalse(info *types.Info, stmt ast.Stmt) int {
	if ret, ok := stmt.(*ast.ReturnStmt); ok && len(ret.Results) == 1 {
		return isTrueOrFalse(info, ret.Results[0])
	}
	return 0
}

// isTrueOrFalse returns nonzero if expr is literally true (+1) or false (-1).
func isTrueOrFalse(info *types.Info, expr ast.Expr) int {
	if id, ok := expr.(*ast.Ident); ok {
		switch info.Uses[id] {
		case builtinTrue:
			return +1
		case builtinFalse:
			return -1
		}
	}
	return 0
}


================================================
FILE: go/analysis/passes/modernize/slicesdelete.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

// Warning: this analyzer is not safe to enable by default (not nil-preserving).
var SlicesDeleteAnalyzer = &analysis.Analyzer{
	Name:     "slicesdelete",
	Doc:      analyzerutil.MustExtractDoc(doc, "slicesdelete"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      slicesdelete,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicesdelete",
}

// The slicesdelete pass attempts to replace instances of append(s[:i], s[i+k:]...)
// with slices.Delete(s, i, i+k) where k is some positive constant.
// Other variations that will also have suggested replacements include:
// append(s[:i-1], s[i:]...) and append(s[:i+k1], s[i+k2:]) where k2 > k1.
func slicesdelete(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "runtime") {
		return nil, nil
	}

	info := pass.TypesInfo
	report := func(file *ast.File, call *ast.CallExpr, slice1, slice2 *ast.SliceExpr) {
		insert := func(pos token.Pos, text string) analysis.TextEdit {
			return analysis.TextEdit{Pos: pos, End: pos, NewText: []byte(text)}
		}
		isIntExpr := func(e ast.Expr) bool {
			return types.Identical(types.Default(info.TypeOf(e)), builtinInt.Type())
		}
		isIntShadowed := func() bool {
			scope := info.Scopes[file].Innermost(call.Lparen)
			if _, obj := scope.LookupParent("int", call.Lparen); obj != builtinInt {
				return true // int type is shadowed
			}
			return false
		}

		prefix, edits := refactor.AddImport(info, file, "slices", "slices", "Delete", call.Pos())
		// append's indices may be any integer type; slices.Delete requires int.
		// Insert int conversions as needed (and if possible).
		if isIntShadowed() && (!isIntExpr(slice1.High) || !isIntExpr(slice2.Low)) {
			return
		}
		if !isIntExpr(slice1.High) {
			edits = append(edits,
				insert(slice1.High.Pos(), "int("),
				insert(slice1.High.End(), ")"),
			)
		}
		if !isIntExpr(slice2.Low) {
			edits = append(edits,
				insert(slice2.Low.Pos(), "int("),
				insert(slice2.Low.End(), ")"),
			)
		}

		pass.Report(analysis.Diagnostic{
			Pos:     call.Pos(),
			End:     call.End(),
			Message: "Replace append with slices.Delete",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Replace append with slices.Delete",
				TextEdits: append(edits, []analysis.TextEdit{
					// Change name of called function.
					{
						Pos:     call.Fun.Pos(),
						End:     call.Fun.End(),
						NewText: []byte(prefix + "Delete"),
					},
					// Delete ellipsis.
					{
						Pos: call.Ellipsis,
						End: call.Ellipsis + token.Pos(len("...")), // delete ellipsis
					},
					// Remove second slice variable name.
					{
						Pos: slice2.X.Pos(),
						End: slice2.X.End(),
					},
					// Insert after first slice variable name.
					{
						Pos:     slice1.X.End(),
						NewText: []byte(", "),
					},
					// Remove brackets and colons.
					{
						Pos: slice1.Lbrack,
						End: slice1.High.Pos(),
					},
					{
						Pos: slice1.Rbrack,
						End: slice1.Rbrack + 1,
					},
					{
						Pos: slice2.Lbrack,
						End: slice2.Lbrack + 1,
					},
					{
						Pos: slice2.Low.End(),
						End: slice2.Rbrack + 1,
					},
				}...),
			}},
		})
	}
	for curFile := range filesUsingGoVersion(pass, versions.Go1_21) {
		file := curFile.Node().(*ast.File)
		for curCall := range curFile.Preorder((*ast.CallExpr)(nil)) {
			call := curCall.Node().(*ast.CallExpr)
			if id, ok := call.Fun.(*ast.Ident); ok && len(call.Args) == 2 {
				// Verify we have append with two slices and ... operator,
				// the first slice has no low index and second slice has no
				// high index, and not a three-index slice.
				if call.Ellipsis.IsValid() && info.Uses[id] == builtinAppend {
					slice1, ok1 := call.Args[0].(*ast.SliceExpr)
					slice2, ok2 := call.Args[1].(*ast.SliceExpr)
					if ok1 && slice1.Low == nil && !slice1.Slice3 &&
						ok2 && slice2.High == nil && !slice2.Slice3 &&
						astutil.EqualSyntax(slice1.X, slice2.X) &&
						typesinternal.NoEffects(info, slice1.X) &&
						increasingSliceIndices(info, slice1.High, slice2.Low) {
						// Have append(s[:a], s[b:]...) where we can verify a < b.
						report(file, call, slice1, slice2)
					}
				}
			}
		}
	}
	return nil, nil
}

// Given two slice indices a and b, returns true if we can verify that a < b.
// It recognizes certain forms such as i+k1 < i+k2 where k1 < k2.
func increasingSliceIndices(info *types.Info, a, b ast.Expr) bool {
	// Given an expression of the form i±k, returns (i, k)
	// where k is a signed constant. Otherwise it returns (e, 0).
	split := func(e ast.Expr) (ast.Expr, constant.Value) {
		if binary, ok := e.(*ast.BinaryExpr); ok && (binary.Op == token.SUB || binary.Op == token.ADD) {
			// Negate constants if operation is subtract instead of add
			if k := info.Types[binary.Y].Value; k != nil {
				return binary.X, constant.UnaryOp(binary.Op, k, 0) // i ± k
			}
		}
		return e, constant.MakeInt64(0)
	}

	// Handle case where either a or b is a constant
	ak := info.Types[a].Value
	bk := info.Types[b].Value
	if ak != nil || bk != nil {
		return ak != nil && bk != nil && constant.Compare(ak, token.LSS, bk)
	}

	ai, ak := split(a)
	bi, bk := split(b)
	return astutil.EqualSyntax(ai, bi) && constant.Compare(ak, token.LSS, bk)
}


================================================
FILE: go/analysis/passes/modernize/sortslice.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

// (Not to be confused with go/analysis/passes/sortslice.)
var SlicesSortAnalyzer = &analysis.Analyzer{
	Name: "slicessort",
	Doc:  analyzerutil.MustExtractDoc(doc, "slicessort"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: slicessort,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicessort",
}

// The slicessort pass replaces sort.Slice(slice, less) with
// slices.Sort(slice) when slice is a []T and less is a FuncLit
// equivalent to cmp.Ordered[T].
//
//		sort.Slice(s, func(i, j int) bool { return s[i] < s[j] })
//	  =>	slices.Sort(s)
//
// There is no slices.SortStable.
//
// TODO(adonovan): support
//
//   - sort.Slice(s, func(i, j int) bool { return s[i] ... s[j] })
//     -> slices.SortFunc(s, func(x, y T) int { return x ... y })
//     iff all uses of i, j can be replaced by s[i], s[j] and "<" can be replaced with cmp.Compare.
//
//   - As above for sort.SliceStable -> slices.SortStableFunc.
//
//   - sort.Sort(x) where x has a named slice type whose Less method is the natural order.
//     -> sort.Slice(x)
func slicessort(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "slices", "sort", "runtime") {
		return nil, nil
	}

	var (
		info      = pass.TypesInfo
		index     = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		sortSlice = index.Object("sort", "Slice")
	)
	for curCall := range index.Calls(sortSlice) {
		call := curCall.Node().(*ast.CallExpr)
		if lit, ok := call.Args[1].(*ast.FuncLit); ok && len(lit.Body.List) == 1 {
			sig := info.Types[lit.Type].Type.(*types.Signature)

			// Have: sort.Slice(s, func(i, j int) bool { return ... })
			s := call.Args[0]
			i := sig.Params().At(0)
			j := sig.Params().At(1)

			if ret, ok := lit.Body.List[0].(*ast.ReturnStmt); ok {
				if compare, ok := ret.Results[0].(*ast.BinaryExpr); ok && compare.Op == token.LSS {
					// isIndex reports whether e is s[v].
					isIndex := func(e ast.Expr, v *types.Var) bool {
						index, ok := e.(*ast.IndexExpr)
						return ok &&
							astutil.EqualSyntax(index.X, s) &&
							is[*ast.Ident](index.Index) &&
							info.Uses[index.Index.(*ast.Ident)] == v
					}
					file := astutil.EnclosingFile(curCall)
					if isIndex(compare.X, i) && isIndex(compare.Y, j) &&
						analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_21) {
						// Have: sort.Slice(s, func(i, j int) bool { return s[i] < s[j] })

						prefix, importEdits := refactor.AddImport(
							info, file, "slices", "slices", "Sort", call.Pos())

						pass.Report(analysis.Diagnostic{
							// Highlight "sort.Slice".
							Pos:     call.Fun.Pos(),
							End:     call.Fun.End(),
							Message: "sort.Slice can be modernized using slices.Sort",
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: "Replace sort.Slice call by slices.Sort",
								TextEdits: append(importEdits, []analysis.TextEdit{
									{
										// Replace sort.Slice with slices.Sort.
										Pos:     call.Fun.Pos(),
										End:     call.Fun.End(),
										NewText: []byte(prefix + "Sort"),
									},
									{
										// Eliminate FuncLit.
										Pos: call.Args[0].End(),
										End: call.Rparen,
									},
								}...),
							}},
						})
					}
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/stditerators.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

var stditeratorsAnalyzer = &analysis.Analyzer{
	Name: "stditerators",
	Doc:  analyzerutil.MustExtractDoc(doc, "stditerators"),
	Requires: []*analysis.Analyzer{
		typeindexanalyzer.Analyzer,
	},
	Run: stditerators,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stditerators",
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.StdIteratorsModernizer = stditeratorsAnalyzer
}

// stditeratorsTable records std types that have legacy T.{Len,At}
// iteration methods as well as a newer T.All method that returns an
// iter.Seq.
var stditeratorsTable = [...]struct {
	pkgpath, typename, lenmethod, atmethod, itermethod, elemname string

	seqn int // 1 or 2 => "for x" or "for _, x"
}{
	// Example: in go/types, (*Tuple).Variables returns an
	// iterator that replaces a loop over (*Tuple).{Len,At}.
	// The loop variable is named "v".
	{"go/types", "Interface", "NumEmbeddeds", "EmbeddedType", "EmbeddedTypes", "etyp", 1},
	{"go/types", "Interface", "NumExplicitMethods", "ExplicitMethod", "ExplicitMethods", "method", 1},
	{"go/types", "Interface", "NumMethods", "Method", "Methods", "method", 1},
	{"go/types", "MethodSet", "Len", "At", "Methods", "method", 1},
	{"go/types", "Named", "NumMethods", "Method", "Methods", "method", 1},
	{"go/types", "Scope", "NumChildren", "Child", "Children", "child", 1},
	{"go/types", "Struct", "NumFields", "Field", "Fields", "field", 1},
	{"go/types", "Tuple", "Len", "At", "Variables", "v", 1},
	{"go/types", "TypeList", "Len", "At", "Types", "t", 1},
	{"go/types", "TypeParamList", "Len", "At", "TypeParams", "tparam", 1},
	{"go/types", "Union", "Len", "Term", "Terms", "term", 1},
	{"reflect", "Type", "NumField", "Field", "Fields", "field", 1},
	{"reflect", "Type", "NumMethod", "Method", "Methods", "method", 1},
	{"reflect", "Type", "NumIn", "In", "Ins", "in", 1},
	{"reflect", "Type", "NumOut", "Out", "Outs", "out", 1},
	{"reflect", "Value", "NumField", "Field", "Fields", "field", 2},
	{"reflect", "Value", "NumMethod", "Method", "Methods", "method", 2},
}

// stditerators suggests fixes to replace loops using Len/At-style
// iterator APIs by a range loop over an iterator. The set of
// participating types and methods is defined by [iteratorsTable].
//
// Pattern:
//
//	for i := 0; i < x.Len(); i++ {
//		use(x.At(i))
//	}
//
// =>
//
//	for elem := range x.All() {
//		use(elem)
//	}
//
// Variant:
//
//	for i := range x.Len() { ... }
//
// Note: Iterators have a dynamic cost. How do we know that
// the user hasn't intentionally chosen not to use an
// iterator for that reason? We don't want to go fix to
// undo optimizations. Do we need a suppression mechanism?
//
// TODO(adonovan): recognize the more complex patterns that
// could make full use of both components of an iter.Seq2, e.g.
//
//	for i := 0; i < v.NumField(); i++ {
//		use(v.Field(i), v.Type().Field(i))
//	}
//
// =>
//
//	for structField, field := range v.Fields() {
//		use(structField, field)
//	}
func stditerators(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo
	)

	for _, row := range stditeratorsTable {
		// Don't offer fixes within the package
		// that defines the iterator in question.
		if within(pass, row.pkgpath) {
			continue
		}

		var (
			lenMethod = index.Selection(row.pkgpath, row.typename, row.lenmethod)
			atMethod  = index.Selection(row.pkgpath, row.typename, row.atmethod)
		)

		// chooseName returns an appropriate fresh name
		// for the index variable of the iterator loop
		// whose body is specified.
		//
		// If the loop body starts with
		//
		//     for ... { e := x.At(i); use(e) }
		//
		// or
		//
		//     for ... { if e := x.At(i); cond { use(e) } }
		//
		// then chooseName prefers the name e and additionally
		// returns the var's symbol. We'll transform this to:
		//
		//     for e := range x.Len() { e := e; use(e) }
		//
		// which leaves a redundant assignment that a
		// subsequent 'forvar' pass will eliminate.
		chooseName := func(curBody inspector.Cursor, x ast.Expr, i *types.Var) (string, *types.Var) {

			// isVarAssign reports whether stmt has the form v := x.At(i)
			// and returns the variable if so.
			isVarAssign := func(stmt ast.Stmt) *types.Var {
				if assign, ok := stmt.(*ast.AssignStmt); ok &&
					assign.Tok == token.DEFINE &&
					len(assign.Lhs) == 1 &&
					len(assign.Rhs) == 1 &&
					is[*ast.Ident](assign.Lhs[0]) {
					// call to x.At(i)?
					if call, ok := assign.Rhs[0].(*ast.CallExpr); ok &&
						typeutil.Callee(info, call) == atMethod &&
						astutil.EqualSyntax(ast.Unparen(call.Fun).(*ast.SelectorExpr).X, x) &&
						is[*ast.Ident](call.Args[0]) &&
						info.Uses[call.Args[0].(*ast.Ident)] == i {
						// Have: elem := x.At(i)
						id := assign.Lhs[0].(*ast.Ident)
						return info.Defs[id].(*types.Var)
					}
				}
				return nil
			}

			body := curBody.Node().(*ast.BlockStmt)
			if len(body.List) > 0 {
				// Is body { elem := x.At(i); ... } ?
				if v := isVarAssign(body.List[0]); v != nil {
					return v.Name(), v
				}

				// Or { if elem := x.At(i); cond { ... } } ?
				if ifstmt, ok := body.List[0].(*ast.IfStmt); ok && ifstmt.Init != nil {
					if v := isVarAssign(ifstmt.Init); v != nil {
						return v.Name(), v
					}
				}
			}

			loop := curBody.Parent().Node()
			// We generate a new name only if the preferred name is already declared here
			// and is used within the loop body.
			name := freshName(info, index, info.Scopes[loop], loop.Pos(), curBody, curBody, token.NoPos, row.elemname)
			return name, nil
		}

		// Process each call of x.Len().
	nextCall:
		for curLenCall := range index.Calls(lenMethod) {
			lenSel, ok := ast.Unparen(curLenCall.Node().(*ast.CallExpr).Fun).(*ast.SelectorExpr)
			if !ok {
				continue
			}
			// lenSel is "x.Len"

			var (
				rng      analysis.Range   // where to report diagnostic
				curBody  inspector.Cursor // loop body
				indexVar *types.Var       // old loop index var
				elemVar  *types.Var       // existing "elem := x.At(i)" var, if present
				elem     string           // name for new loop var
				edits    []analysis.TextEdit
			)

			// Analyze enclosing loop.
			switch curLenCall.ParentEdgeKind() {
			case edge.BinaryExpr_Y:
				// pattern 1: for i := 0; i < x.Len(); i++ { ... }
				var (
					curCmp = curLenCall.Parent()
					cmp    = curCmp.Node().(*ast.BinaryExpr)
				)
				if cmp.Op != token.LSS ||
					curCmp.ParentEdgeKind() != edge.ForStmt_Cond {
					continue
				}
				if id, ok := cmp.X.(*ast.Ident); ok {
					// Have: for _; i < x.Len(); _ { ... }
					var (
						v      = info.Uses[id].(*types.Var)
						curFor = curCmp.Parent()
						loop   = curFor.Node().(*ast.ForStmt)
					)
					if v != isIncrementLoop(info, loop) {
						continue
					}
					// Have: for i := 0; i < x.Len(); i++ { ... }.
					//       ~~~~~~~~~~~~~~~~~~~~~~~~~~~~
					rng = astutil.RangeOf(loop.For, loop.Post.End())
					indexVar = v
					curBody = curFor.ChildAt(edge.ForStmt_Body, -1)
					elem, elemVar = chooseName(curBody, lenSel.X, indexVar)
					elemPrefix := cond(row.seqn == 2, "_, ", "")

					//	for i       := 0; i < x.Len(); i++ {
					//          ----       -------  ---  -----
					//	for elem    := range  x.All()      {
					// or   for _, elem := ...
					edits = []analysis.TextEdit{
						{
							Pos:     v.Pos(),
							End:     v.Pos() + token.Pos(len(v.Name())),
							NewText: []byte(elemPrefix + elem),
						},
						{
							Pos:     loop.Init.(*ast.AssignStmt).Rhs[0].Pos(),
							End:     cmp.Y.Pos(),
							NewText: []byte("range "),
						},
						{
							Pos:     lenSel.Sel.Pos(),
							End:     lenSel.Sel.End(),
							NewText: []byte(row.itermethod),
						},
						{
							Pos: curLenCall.Node().End(),
							End: loop.Post.End(),
						},
					}
				}

			case edge.RangeStmt_X:
				// pattern 2: for i := range x.Len() { ... }
				var (
					curRange = curLenCall.Parent()
					loop     = curRange.Node().(*ast.RangeStmt)
				)
				if id, ok := loop.Key.(*ast.Ident); ok &&
					loop.Value == nil &&
					loop.Tok == token.DEFINE {
					// Have: for i := range x.Len() { ... }
					//                ~~~~~~~~~~~~~

					rng = astutil.RangeOf(loop.Range, loop.X.End())
					indexVar = info.Defs[id].(*types.Var)
					curBody = curRange.ChildAt(edge.RangeStmt_Body, -1)
					elem, elemVar = chooseName(curBody, lenSel.X, indexVar)
					elemPrefix := cond(row.seqn == 2, "_, ", "")

					//	for i    := range x.Len() {
					//          ----            ---
					//	for elem := range x.All() {
					edits = []analysis.TextEdit{
						{
							Pos:     loop.Key.Pos(),
							End:     loop.Key.End(),
							NewText: []byte(elemPrefix + elem),
						},
						{
							Pos:     lenSel.Sel.Pos(),
							End:     lenSel.Sel.End(),
							NewText: []byte(row.itermethod),
						},
					}
				}
			}

			if indexVar == nil {
				continue // no loop of the required form
			}

			// TODO(adonovan): what about possible
			// modifications of x within the loop?
			// Aliasing seems to make a conservative
			// treatment impossible.

			// Check that all uses of var i within loop body are x.At(i).
			for curUse := range index.Uses(indexVar) {
				if !curBody.Contains(curUse) {
					continue
				}
				if ek, argidx := curUse.ParentEdge(); ek != edge.CallExpr_Args || argidx != 0 {
					continue nextCall // use is not arg of call
				}
				curAtCall := curUse.Parent()
				atCall := curAtCall.Node().(*ast.CallExpr)
				if typeutil.Callee(info, atCall) != atMethod {
					continue nextCall // use is not arg of call to T.At
				}
				atSel := ast.Unparen(atCall.Fun).(*ast.SelectorExpr)

				// Check receivers of Len, At calls match (syntactically).
				if !astutil.EqualSyntax(lenSel.X, atSel.X) {
					continue nextCall
				}

				// At each point of use, check that
				// the fresh variable is not shadowed
				// by an intervening local declaration
				// (or by the idiomatic elemVar optionally
				// found by chooseName).
				if obj := lookup(info, curAtCall, elem); obj != nil && obj != elemVar && obj.Pos() > indexVar.Pos() {
					// (Ideally, instead of giving up, we would
					// embellish the name and try again.)
					continue nextCall
				}

				// use(x.At(i))
				//     -------
				// use(elem   )
				edits = append(edits, analysis.TextEdit{
					Pos:     atCall.Pos(),
					End:     atCall.End(),
					NewText: []byte(elem),
				})
			}

			// Check file Go version is new enough for the iterator method.
			// (In the long run, version filters are not highly selective,
			// so there's no need to do them first, especially as this check
			// may be somewhat expensive.)
			if v, err := methodGoVersion(row.pkgpath, row.typename, row.itermethod); err != nil {
				panic(err)
			} else if !analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(curLenCall), v.String()) {
				continue nextCall
			}

			pass.Report(analysis.Diagnostic{
				Pos: rng.Pos(),
				End: rng.End(),
				Message: fmt.Sprintf("%s/%s loop can simplified using %s.%s iteration",
					row.lenmethod, row.atmethod, row.typename, row.itermethod),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: fmt.Sprintf(
						"Replace %s/%s loop with %s.%s iteration",
						row.lenmethod, row.atmethod, row.typename, row.itermethod),
					TextEdits: edits,
				}},
			})
		}
	}
	return nil, nil
}

// -- helpers --

// methodGoVersion reports the version at which the method
// (pkgpath.recvtype).method appeared in the standard library.
func methodGoVersion(pkgpath, recvtype, method string) (stdlib.Version, error) {
	// TODO(adonovan): opt: this might be inefficient for large packages
	// like go/types. If so, memoize using a map (and kill two birds with
	// one stone by also memoizing the 'within' check above).
	for _, sym := range stdlib.PackageSymbols[pkgpath] {
		if sym.Kind == stdlib.Method {
			_, recv, name := sym.SplitMethod()
			if recv == recvtype && name == method {
				return sym.Version, nil
			}
		}
	}
	return 0, fmt.Errorf("methodGoVersion: %s.%s.%s missing from stdlib manifest", pkgpath, recvtype, method)
}


================================================
FILE: go/analysis/passes/modernize/stringsbuilder.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"cmp"
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"maps"
	"slices"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

var StringsBuilderAnalyzer = &analysis.Analyzer{
	Name: "stringsbuilder",
	Doc:  analyzerutil.MustExtractDoc(doc, "stringsbuilder"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: stringsbuilder,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringbuilder",
}

// stringsbuilder replaces string += string in a loop by strings.Builder.
func stringsbuilder(pass *analysis.Pass) (any, error) {
	// Skip the analyzer in packages where its
	// fixes would create an import cycle.
	if within(pass, "strings", "runtime") {
		return nil, nil
	}

	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		index   = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	)

	// Gather all local string variables that appear on the
	// LHS of some string += string assignment.
	candidates := make(map[*types.Var]bool)
	for curAssign := range inspect.Root().Preorder((*ast.AssignStmt)(nil)) {
		assign := curAssign.Node().(*ast.AssignStmt)
		if assign.Tok == token.ADD_ASSIGN && is[*ast.Ident](assign.Lhs[0]) {
			if v, ok := pass.TypesInfo.Uses[assign.Lhs[0].(*ast.Ident)].(*types.Var); ok &&
				v.Kind() == types.LocalVar &&
				types.Identical(v.Type(), builtinString.Type()) {
				candidates[v] = true
			}
		}
	}

	lexicalOrder := func(x, y *types.Var) int { return cmp.Compare(x.Pos(), y.Pos()) }

	// File and Pos of last fix edit,
	// for overlapping fix span detection.
	var (
		lastEditFile *ast.File
		lastEditEnd  token.Pos
	)

	// Now check each candidate variable's decl and uses.
nextcand:
	for _, v := range slices.SortedFunc(maps.Keys(candidates), lexicalOrder) {
		var edits []analysis.TextEdit

		// Check declaration of s has one of these forms:
		//
		//    s := expr
		//    var s [string] [= expr]
		//    var ( ...; s [string] [= expr] )			(s is last)
		//
		// and transform to one of:
		//
		//    var   s strings.Builder ; s.WriteString(expr)
		//    var ( s strings.Builder); s.WriteString(expr)
		//
		def, ok := index.Def(v)
		if !ok {
			continue
		}

		// To avoid semantic conflicts, do not offer a fix if its edit
		// range (ignoring import edits) overlaps a previous fix.
		// This fixes #76983 and is an ad-hoc mitigation of #76476.
		file := astutil.EnclosingFile(def)
		if file == lastEditFile && v.Pos() < lastEditEnd {
			continue
		}

		ek := def.ParentEdgeKind()
		if ek == edge.AssignStmt_Lhs &&
			len(def.Parent().Node().(*ast.AssignStmt).Lhs) == 1 {
			// Have: s := expr
			// => var s strings.Builder; s.WriteString(expr)

			assign := def.Parent().Node().(*ast.AssignStmt)

			// Reject "if s := f(); ..." since in that context
			// we can't replace the assign with two statements.
			switch def.Parent().Parent().Node().(type) {
			case *ast.BlockStmt, *ast.CaseClause, *ast.CommClause:
				// OK: these are the parts of syntax that
				// allow unrestricted statement lists.
			default:
				continue
			}

			// Add strings import.
			prefix, importEdits := refactor.AddImport(
				pass.TypesInfo, astutil.EnclosingFile(def), "strings", "strings", "Builder", v.Pos())
			edits = append(edits, importEdits...)

			if isEmptyString(pass.TypesInfo, assign.Rhs[0]) {
				// s := ""
				// ---------------------
				// var s strings.Builder
				edits = append(edits, analysis.TextEdit{
					Pos:     assign.Pos(),
					End:     assign.End(),
					NewText: fmt.Appendf(nil, "var %[1]s %[2]sBuilder", v.Name(), prefix),
				})

			} else {
				// s :=                                 expr
				// -------------------------------------    -
				// var s strings.Builder; s.WriteString(expr)
				edits = append(edits, []analysis.TextEdit{
					{
						Pos:     assign.Pos(),
						End:     assign.Rhs[0].Pos(),
						NewText: fmt.Appendf(nil, "var %[1]s %[2]sBuilder; %[1]s.WriteString(", v.Name(), prefix),
					},
					{
						Pos:     assign.End(),
						End:     assign.End(),
						NewText: []byte(")"),
					},
				}...)

			}

		} else if ek == edge.ValueSpec_Names &&
			len(def.Parent().Node().(*ast.ValueSpec).Names) == 1 &&
			first(def.Parent().Parent().LastChild()) == def.Parent() {
			// Have: var   s [string] [= expr]
			//   or: var ( s [string] [= expr] )
			// => var s strings.Builder; s.WriteString(expr)
			//
			// The LastChild check rejects this case:
			//   var ( s [string] [= expr]; others... )
			// =>
			//   var ( s strings.Builder; others... ); s.WriteString(expr)
			// since it moves 'expr' across 'others', requiring
			// reformatting of syntax, which in general is lossy
			// of comments and vertical space.
			// We expect this to be rare.

			// Add strings import.
			prefix, importEdits := refactor.AddImport(
				pass.TypesInfo, astutil.EnclosingFile(def), "strings", "strings", "Builder", v.Pos())
			edits = append(edits, importEdits...)

			spec := def.Parent().Node().(*ast.ValueSpec)
			decl := def.Parent().Parent().Node().(*ast.GenDecl)

			init := spec.Names[0].End() // start of " = expr"
			if spec.Type != nil {
				init = spec.Type.End()
			}

			// Replace (possibly absent) type:
			//
			// var s [string]
			//      ----------------
			// var s strings.Builder
			edits = append(edits, analysis.TextEdit{
				Pos:     spec.Names[0].End(),
				End:     init,
				NewText: fmt.Appendf(nil, " %sBuilder", prefix),
			})

			if len(spec.Values) > 0 && !isEmptyString(pass.TypesInfo, spec.Values[0]) {
				if decl.Rparen.IsValid() {
					// var decl with explicit parens:
					//
					// var ( ...  =               expr )
					//           -                     -
					// var ( ... ); s.WriteString(expr)
					edits = append(edits, []analysis.TextEdit{
						{
							Pos:     init,
							End:     init,
							NewText: []byte(")"),
						},
						{
							Pos: spec.Values[0].End(),
							End: decl.End(),
						},
					}...)
				}

				// =               expr
				// ----------------    -
				// ; s.WriteString(expr)
				edits = append(edits, []analysis.TextEdit{
					{
						Pos:     init,
						End:     spec.Values[0].Pos(),
						NewText: fmt.Appendf(nil, "; %s.WriteString(", v.Name()),
					},
					{
						Pos:     spec.Values[0].End(),
						End:     spec.Values[0].End(),
						NewText: []byte(")"),
					},
				}...)
			} else {
				// delete "= expr"
				edits = append(edits, analysis.TextEdit{
					Pos: init,
					End: spec.End(),
				})
			}

		} else {
			continue
		}

		// Check uses of s.
		//
		// - All uses of s except the final one must be of the form
		//
		//    s += expr
		//
		//   Each of these will become s.WriteString(expr).
		//   At least one of them must be in an intervening loop
		//   w.r.t. the declaration of s:
		//
		//    var s string
		//    for ... { s += expr }
		//
		// - All uses of s after the last += must be rvalue uses (e.g. use(s), not &s).
		//   Each of these will become s.String().
		//
		//   Perhaps surprisingly, it is fine for there to be an
		//   intervening loop or lambda w.r.t. the declaration of s:
		//
		//    var s strings.Builder
		//    for range kSmall { s.WriteString(expr) }
		//    for range kLarge { use(s.String()) } // called repeatedly
		//
		//   Even though that might cause the s.String() operation to be
		//   executed repeatedly, this is not a deoptimization because,
		//   by design, (*strings.Builder).String does not allocate.
		var (
			numLoopAssigns int             // number of += assignments within a loop
			loopAssign     *ast.AssignStmt // first += assignment within a loop
			seenRvalueUse  bool            // => we've seen at least one rvalue use of s
		)
		for curUse := range index.Uses(v) {
			// Strip enclosing parens around Ident.
			ek := curUse.ParentEdgeKind()
			for ek == edge.ParenExpr_X {
				curUse = curUse.Parent()
				ek = curUse.ParentEdgeKind()
			}

			// intervening reports whether cur has an ancestor of
			// one of the given types that is within the scope of v.
			intervening := func(types ...ast.Node) bool {
				for cur := range curUse.Enclosing(types...) {
					if v.Pos() <= cur.Node().Pos() { // in scope of v
						return true
					}
				}
				return false
			}

			if ek == edge.AssignStmt_Lhs {
				// After an rvalue use, no more assignments are allowed.
				if seenRvalueUse {
					continue nextcand
				}

				assign := curUse.Parent().Node().(*ast.AssignStmt)
				if assign.Tok != token.ADD_ASSIGN {
					continue nextcand
				}
				// Have: s += expr

				// At least one of the += operations
				// must appear within a loop.
				// relative to the declaration of s.
				if intervening((*ast.ForStmt)(nil), (*ast.RangeStmt)(nil)) {
					numLoopAssigns++
					if loopAssign == nil {
						loopAssign = assign
					}
				}

				// s +=          expr
				//  -------------    -
				// s.WriteString(expr)
				edits = append(edits, []analysis.TextEdit{
					// replace " += " with ".WriteString("
					{
						Pos:     assign.Lhs[0].End(),
						End:     assign.Rhs[0].Pos(),
						NewText: []byte(".WriteString("),
					},
					// insert ")"
					{
						Pos:     assign.End(),
						End:     assign.End(),
						NewText: []byte(")"),
					},
				}...)

			} else if ek == edge.UnaryExpr_X &&
				curUse.Parent().Node().(*ast.UnaryExpr).Op == token.AND {
				// Have: use(&s)
				continue nextcand // s is used as an lvalue; reject

			} else {
				// The only possible l-value uses of a string variable
				// are assignments (s=expr, s+=expr, etc) and &s.
				// (For strings, we can ignore method calls s.m().)
				// All other uses are r-values.
				seenRvalueUse = true

				edits = append(edits, analysis.TextEdit{
					// insert ".String()"
					Pos:     curUse.Node().End(),
					End:     curUse.Node().End(),
					NewText: []byte(".String()"),
				})
			}
		}
		if !seenRvalueUse {
			continue nextcand // no rvalue use; reject
		}
		if numLoopAssigns == 0 {
			continue nextcand // no += in a loop; reject
		}

		lastEditFile = file
		lastEditEnd = edits[len(edits)-1].End

		pass.Report(analysis.Diagnostic{
			Pos:     loopAssign.Pos(),
			End:     loopAssign.End(),
			Message: "using string += string in a loop is inefficient",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   "Replace string += string with strings.Builder",
				TextEdits: edits,
			}},
		})
	}

	return nil, nil
}

// isEmptyString reports whether e (a string-typed expression) has constant value "".
func isEmptyString(info *types.Info, e ast.Expr) bool {
	tv, ok := info.Types[e]
	return ok && tv.Value != nil && constant.StringVal(tv.Value) == ""
}


================================================
FILE: go/analysis/passes/modernize/stringscut.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"iter"
	"strconv"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var stringscutAnalyzer = &analysis.Analyzer{
	Name: "stringscut",
	Doc:  analyzerutil.MustExtractDoc(doc, "stringscut"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: stringscut,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscut",
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.StringsCutModernizer = stringscutAnalyzer
}

// stringscut offers a fix to replace an occurrence of strings.Index{,Byte} with
// strings.{Cut,Contains}, and similar fixes for functions in the bytes package.
// Consider some candidate for replacement i := strings.Index(s, substr).
// The following must hold for a replacement to occur:
//
//  1. All instances of i and s must be in one of these forms.
//
//     Binary expressions must be inequalities equivalent to
//     "Index failed" (e.g. i < 0) or "Index succeeded" (i >= 0),
//     or identities such as these (and their negations):
//
//     0 > i                 (flips left and right)
//     i <= -1, -1 >= i      (replace strict inequality by non-strict)
//     i == -1, -1 == i      (Index() guarantees i < 0 => i == -1)
//
//     Slice expressions:
//     a: s[:i], s[0:i]
//     b: s[i+len(substr):], s[len(substr) + i:], s[i + const], s[k + i] (where k = len(substr))
//
//  2. There can be no uses of s, substr, or i where they are
//     potentially modified (i.e. in assignments, or function calls with unknown side
//     effects).
//
// Then, the replacement involves the following substitutions:
//
//  1. Replace "i := strings.Index(s, substr)" with "before, after, ok := strings.Cut(s, substr)"
//
//  2. Replace instances of binary expressions (a) with !ok and binary expressions (b) with ok.
//
//  3. Replace slice expressions (a) with "before" and slice expressions (b) with after.
//
//  4. The assignments to before, after, and ok may use the blank identifier "_" if they are unused.
//
//     For example:
//
//     i := strings.Index(s, substr)
//     if i >= 0 {
//     use(s[:i], s[i+len(substr):])
//     }
//
//     Would become:
//
//     before, after, ok := strings.Cut(s, substr)
//     if ok {
//     use(before, after)
//     }
//
// If the condition involving `i` is equivalent to i >= 0, then we replace it with
// `if ok“.
// If the condition is negated (e.g. equivalent to `i < 0`), we use `if !ok` instead.
// If the slices of `s` match `s[:i]` or `s[i+len(substr):]` or their variants listed above,
// then we replace them with before and after.
//
// When the index `i` is used only to check for the presence of the substring or byte slice,
// the suggested fix uses Contains() instead of Cut.
//
// For example:
//
//	i := strings.Index(s, substr)
//	if i >= 0 {
//		return
//	}
//
// Would become:
//
//	found := strings.Contains(s, substr)
//	if found {
//		return
//	}
func stringscut(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo

		stringsIndex     = index.Object("strings", "Index")
		stringsIndexByte = index.Object("strings", "IndexByte")
		bytesIndex       = index.Object("bytes", "Index")
		bytesIndexByte   = index.Object("bytes", "IndexByte")
	)

	scopeFixCount := make(map[*types.Scope]int) // the number of times we have offered a fix within a given scope in the current pass

	for _, obj := range []types.Object{
		stringsIndex,
		stringsIndexByte,
		bytesIndex,
		bytesIndexByte,
	} {
		// (obj may be nil)
	nextcall:
		for curCall := range index.Calls(obj) {
			// Check file version.
			if !analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(curCall), versions.Go1_18) {
				continue // strings.Index not available in this file
			}
			indexCall := curCall.Node().(*ast.CallExpr) // the call to strings.Index, etc.
			obj := typeutil.Callee(info, indexCall)
			if obj == nil {
				continue
			}

			var iIdent *ast.Ident // defining identifier of i var
			switch ek, idx := curCall.ParentEdge(); ek {
			case edge.ValueSpec_Values:
				// Have: var i = strings.Index(...)
				curName := curCall.Parent().ChildAt(edge.ValueSpec_Names, idx)
				iIdent = curName.Node().(*ast.Ident)
			case edge.AssignStmt_Rhs:
				// Have: i := strings.Index(...)
				// (Must be i's definition.)
				curLhs := curCall.Parent().ChildAt(edge.AssignStmt_Lhs, idx)
				iIdent, _ = curLhs.Node().(*ast.Ident) // may be nil
			}

			if iIdent == nil {
				continue
			}
			// Inv: iIdent is i's definition. The following would be skipped: 'var i int; i = strings.Index(...)'
			// Get uses of i.
			iObj := info.ObjectOf(iIdent)
			if iObj == nil {
				continue
			}

			var (
				s      = indexCall.Args[0]
				substr = indexCall.Args[1]
			)

			// Check that there are no statements that alter the value of s
			// or substr after the call to Index().
			if !indexArgValid(info, index, s, indexCall.Pos()) ||
				!indexArgValid(info, index, substr, indexCall.Pos()) {
				continue nextcall
			}

			// Next, examine all uses of i. If the only uses are of the
			// forms mentioned above (e.g. i < 0, i >= 0, s[:i] and s[i +
			// len(substr)]), then we can replace the call to Index()
			// with a call to Cut() and use the returned ok, before,
			// and after variables accordingly.
			negative, nonnegative, beforeSlice, afterSlice := checkIdxUses(pass.TypesInfo, index.Uses(iObj), s, substr, iObj)

			// Either there are no uses of before, after, or ok, or some use
			// of i does not match our criteria - don't suggest a fix.
			if negative == nil && nonnegative == nil && beforeSlice == nil && afterSlice == nil {
				continue
			}

			// If the only uses are ok and !ok, don't suggest a Cut() fix - these should be using Contains()
			isContains := (len(negative) > 0 || len(nonnegative) > 0) && len(beforeSlice) == 0 && len(afterSlice) == 0

			enclosingBlock, ok := moreiters.First(curCall.Enclosing((*ast.BlockStmt)(nil)))
			if !ok {
				continue
			}
			scope := iObj.Parent()
			// Generate fresh names for ok, before, after, found, but only if
			// they are defined by the end of the enclosing block and used
			// within the enclosing block after the Index call. We need a Cursor
			// for the end of the enclosing block, but we can't just find the
			// Cursor at scope.End() because it corresponds to the entire
			// enclosingBlock. Instead, get the last child of the enclosing
			// block.
			lastStmtCur, _ := enclosingBlock.LastChild()
			lastStmt := lastStmtCur.Node()

			fresh := func(preferred string) string {
				return freshName(info, index, scope, lastStmt.End(), lastStmtCur, enclosingBlock, iIdent.Pos(), preferred)
			}

			var okVarName, beforeVarName, afterVarName, foundVarName string
			if isContains {
				foundVarName = fresh("found")
			} else {
				okVarName = fresh("ok")
				beforeVarName = fresh("before")
				afterVarName = fresh("after")
			}

			// If we are already suggesting a fix within the index's scope, we
			// must get fresh names for before, after and ok.
			// This is a specific symptom of the general problem that analyzers
			// can generate conflicting fixes.
			if scopeFixCount[scope] > 0 {
				suffix := scopeFixCount[scope] - 1 // start at 0
				if isContains {
					foundVarName = fresh(fmt.Sprintf("%s%d", foundVarName, suffix))
				} else {
					okVarName = fresh(fmt.Sprintf("%s%d", okVarName, suffix))
					beforeVarName = fresh(fmt.Sprintf("%s%d", beforeVarName, suffix))
					afterVarName = fresh(fmt.Sprintf("%s%d", afterVarName, suffix))
				}
			}

			// If there will be no uses of ok, before, or after, use the
			// blank identifier instead.
			if len(negative) == 0 && len(nonnegative) == 0 {
				okVarName = "_"
			}
			if len(beforeSlice) == 0 {
				beforeVarName = "_"
			}
			if len(afterSlice) == 0 {
				afterVarName = "_"
			}

			var edits []analysis.TextEdit
			replace := func(exprs []ast.Expr, new string) {
				for _, expr := range exprs {
					edits = append(edits, analysis.TextEdit{
						Pos:     expr.Pos(),
						End:     expr.End(),
						NewText: []byte(new),
					})
				}
			}
			// Get the ident for the call to strings.Index, which could just be
			// "Index" if the strings package is dot imported.
			indexCallId := typesinternal.UsedIdent(info, indexCall.Fun)
			replacedFunc := "Cut"
			if isContains {
				replacedFunc = "Contains"
				replace(negative, "!"+foundVarName) // idx < 0   ->  !found
				replace(nonnegative, foundVarName)  // idx > -1  ->   found

				// Replace the assignment with found, and replace the call to
				// Index or IndexByte with a call to Contains.
				// i     := strings.Index   (...)
				// -----            --------
				// found := strings.Contains(...)
				edits = append(edits, analysis.TextEdit{
					Pos:     iIdent.Pos(),
					End:     iIdent.End(),
					NewText: []byte(foundVarName),
				}, analysis.TextEdit{
					Pos:     indexCallId.Pos(),
					End:     indexCallId.End(),
					NewText: []byte("Contains"),
				})
			} else {
				replace(negative, "!"+okVarName)    // idx < 0   ->  !ok
				replace(nonnegative, okVarName)     // idx > -1  ->   ok
				replace(beforeSlice, beforeVarName) // s[:idx]   ->   before
				replace(afterSlice, afterVarName)   // s[idx+k:] ->   after

				// Replace the assignment with before, after, ok, and replace
				// the call to Index or IndexByte with a call to Cut.
				// i     			 := strings.Index(...)
				// -----------------            -----
				// before, after, ok := strings.Cut  (...)
				edits = append(edits, analysis.TextEdit{
					Pos:     iIdent.Pos(),
					End:     iIdent.End(),
					NewText: fmt.Appendf(nil, "%s, %s, %s", beforeVarName, afterVarName, okVarName),
				}, analysis.TextEdit{
					Pos:     indexCallId.Pos(),
					End:     indexCallId.End(),
					NewText: []byte("Cut"),
				})
			}

			// Calls to IndexByte have a byte as their second arg, which
			// must be converted to a string or []byte to be a valid arg for Cut/Contains.
			if obj.Name() == "IndexByte" {
				switch obj.Pkg().Name() {
				case "strings":
					searchByteVal := info.Types[substr].Value
					if searchByteVal == nil {
						// substr is a variable, e.g. substr := byte('b')
						// use string(substr)
						edits = append(edits, []analysis.TextEdit{
							{
								Pos:     substr.Pos(),
								NewText: []byte("string("),
							},
							{
								Pos:     substr.End(),
								NewText: []byte(")"),
							},
						}...)
					} else {
						// substr is a byte constant
						val, _ := constant.Int64Val(searchByteVal) // inv: must be a valid byte
						// strings.Cut/Contains requires a string, so convert byte literal to string literal; e.g. 'a' -> "a", 55 -> "7"
						edits = append(edits, analysis.TextEdit{
							Pos:     substr.Pos(),
							End:     substr.End(),
							NewText: strconv.AppendQuote(nil, string(byte(val))),
						})
					}
				case "bytes":
					// bytes.Cut/Contains requires a []byte, so wrap substr in a []byte{}
					edits = append(edits, []analysis.TextEdit{
						{
							Pos:     substr.Pos(),
							NewText: []byte("[]byte{"),
						},
						{
							Pos:     substr.End(),
							NewText: []byte("}"),
						},
					}...)
				}
			}
			scopeFixCount[scope]++
			pass.Report(analysis.Diagnostic{
				Pos: indexCall.Fun.Pos(),
				End: indexCall.Fun.End(),
				Message: fmt.Sprintf("%s.%s can be simplified using %s.%s",
					obj.Pkg().Name(), obj.Name(), obj.Pkg().Name(), replacedFunc),
				Category: "stringscut",
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   fmt.Sprintf("Simplify %s.%s call using %s.%s", obj.Pkg().Name(), obj.Name(), obj.Pkg().Name(), replacedFunc),
					TextEdits: edits,
				}},
			})
		}
	}

	return nil, nil
}

// indexArgValid reports whether expr is a valid strings.Index(_, _) arg
// for the transformation. An arg is valid iff it is:
// - constant;
// - a local variable with no modifying uses after the Index() call; or
// - []byte(x) where x is also valid by this definition.
// All other expressions are assumed not referentially transparent,
// so we cannot be sure that all uses are safe to replace.
func indexArgValid(info *types.Info, index *typeindex.Index, expr ast.Expr, afterPos token.Pos) bool {
	tv := info.Types[expr]
	if tv.Value != nil {
		return true // constant
	}
	switch expr := expr.(type) {
	case *ast.CallExpr:
		return types.Identical(tv.Type, byteSliceType) &&
			info.Types[expr.Fun].IsType() && // make sure this isn't a function that returns a byte slice
			indexArgValid(info, index, expr.Args[0], afterPos) // check s in []byte(s)
	case *ast.Ident:
		sObj := info.Uses[expr]
		sUses := index.Uses(sObj)
		return !hasModifyingUses(info, sUses, afterPos)
	default:
		// For now, skip instances where s or substr are not
		// identifers, basic lits, or call expressions of the form
		// []byte(s).
		// TODO(mkalil): Handle s and substr being expressions like ptr.field[i].
		// From adonovan: We'd need to analyze s and substr to see
		// whether they are referentially transparent, and if not,
		// analyze all code between declaration and use and see if
		// there are statements or expressions with potential side
		// effects.
		return false
	}
}

// checkIdxUses inspects the uses of i to make sure they match certain criteria that
// allows us to suggest a modernization. If all uses of i, s and substr match
// one of the following four valid formats, it returns a list of occurrences for
// each format. If any of the uses do not match one of the formats, return nil
// for all values, since we should not offer a replacement.
// 1. negative - a condition equivalent to i < 0
// 2. nonnegative - a condition equivalent to i >= 0
// 3. beforeSlice - a slice of `s` that matches either s[:i], s[0:i]
// 4. afterSlice - a slice of `s` that matches one of: s[i+len(substr):], s[len(substr) + i:], s[i + const], s[k + i] (where k = len(substr))
//
// Additionally, all beforeSlice and afterSlice uses must be dominated by a
// nonnegative guard on i (i.e., inside the body of an if whose condition
// checks i >= 0, or in the else of a negative check, or after an
// early-return negative check). This ensures that the rewrite from
// s[i+len(sep):] to "after" preserves semantics, since when i == -1,
// s[i+len(sep):] may yield a valid substring (e.g. s[0:] for single-byte
// separators), but "after" would be "".
//
// When len(substr)==1, it's safe to use s[i+1:] even when i < 0.
// Otherwise, each replacement of s[i+1:] must be guarded by a check
// that i is nonnegative.
func checkIdxUses(info *types.Info, uses iter.Seq[inspector.Cursor], s, substr ast.Expr, iObj types.Object) (negative, nonnegative, beforeSlice, afterSlice []ast.Expr) {
	requireGuard := true
	if l := constSubstrLen(info, substr); l != -1 && l != 1 {
		requireGuard = false
	}

	use := func(cur inspector.Cursor) bool {
		ek := cur.ParentEdgeKind()
		n := cur.Parent().Node()
		switch ek {
		case edge.BinaryExpr_X, edge.BinaryExpr_Y:
			check := n.(*ast.BinaryExpr)
			switch checkIdxComparison(info, check, iObj) {
			case -1:
				negative = append(negative, check)
				return true
			case 1:
				nonnegative = append(nonnegative, check)
				return true
			}
			// Check is not equivalent to that i < 0 or i >= 0.
			// Might be part of an outer slice expression like s[i + k]
			// which requires a different check.
			// Check that the thing being sliced is s and that the slice
			// doesn't have a max index.
			if slice, ok := cur.Parent().Parent().Node().(*ast.SliceExpr); ok &&
				sameObject(info, s, slice.X) &&
				slice.Max == nil {
				if isBeforeSlice(info, ek, slice) && (!requireGuard || isSliceIndexGuarded(info, cur, iObj)) {
					beforeSlice = append(beforeSlice, slice)
					return true
				} else if isAfterSlice(info, ek, slice, substr) && (!requireGuard || isSliceIndexGuarded(info, cur, iObj)) {
					afterSlice = append(afterSlice, slice)
					return true
				}
			}
		case edge.SliceExpr_Low, edge.SliceExpr_High:
			slice := n.(*ast.SliceExpr)
			// Check that the thing being sliced is s and that the slice doesn't
			// have a max index.
			if sameObject(info, s, slice.X) && slice.Max == nil {
				if isBeforeSlice(info, ek, slice) && (!requireGuard || isSliceIndexGuarded(info, cur, iObj)) {
					beforeSlice = append(beforeSlice, slice)
					return true
				} else if isAfterSlice(info, ek, slice, substr) && (!requireGuard || isSliceIndexGuarded(info, cur, iObj)) {
					afterSlice = append(afterSlice, slice)
					return true
				}
			}
		}
		return false
	}

	for curIdent := range uses {
		if !use(curIdent) {
			return nil, nil, nil, nil
		}
	}
	return negative, nonnegative, beforeSlice, afterSlice
}

// hasModifyingUses reports whether any of the uses involve potential
// modifications. Uses involving assignments before the "afterPos" won't be
// considered.
func hasModifyingUses(info *types.Info, uses iter.Seq[inspector.Cursor], afterPos token.Pos) bool {
	for curUse := range uses {
		ek := curUse.ParentEdgeKind()
		if ek == edge.AssignStmt_Lhs {
			if curUse.Node().Pos() <= afterPos {
				continue
			}
			assign := curUse.Parent().Node().(*ast.AssignStmt)
			if sameObject(info, assign.Lhs[0], curUse.Node().(*ast.Ident)) {
				// Modifying use because we are reassigning the value of the object.
				return true
			}
		} else if ek == edge.UnaryExpr_X &&
			curUse.Parent().Node().(*ast.UnaryExpr).Op == token.AND {
			// Modifying use because we might be passing the object by reference (an explicit &).
			// We can ignore the case where we have a method call on the expression (which
			// has an implicit &) because we know the type of s and substr are strings
			// which cannot have methods on them.
			return true
		}
	}
	return false
}

// checkIdxComparison reports whether the check is equivalent to i < 0 or its negation, or neither.
// For equivalent to i >= 0, we only accept this exact BinaryExpr since
// expressions like i > 0 or i >= 1 make a stronger statement about the value of i.
// We avoid suggesting a fix in this case since it may result in an invalid
// transformation (See golang/go#76687).
// Since strings.Index returns exactly -1 if the substring is not found, we
// don't need to handle expressions like i <= -3.
// We return 0 if the expression does not match any of these options.
func checkIdxComparison(info *types.Info, check *ast.BinaryExpr, iObj types.Object) int {
	isI := func(e ast.Expr) bool {
		id, ok := e.(*ast.Ident)
		return ok && info.Uses[id] == iObj
	}
	if !isI(check.X) && !isI(check.Y) {
		return 0
	}

	// Ensure that the constant (if any) is on the right.
	x, op, y := check.X, check.Op, check.Y
	if info.Types[x].Value != nil {
		x, op, y = y, flip(op), x
	}

	yIsInt := func(k int64) bool {
		return isIntLiteral(info, y, k)
	}

	if op == token.LSS && yIsInt(0) || // i < 0
		op == token.EQL && yIsInt(-1) || // i == -1
		op == token.LEQ && yIsInt(-1) { // i <= -1
		return -1 // check <=> i is negative
	}

	if op == token.GEQ && yIsInt(0) || // i >= 0
		op == token.NEQ && yIsInt(-1) || // i != -1
		op == token.GTR && yIsInt(-1) { // i > -1
		return +1 // check <=> i is non-negative
	}

	return 0 // unknown
}

// flip changes the comparison token as if the operands were flipped.
// It is defined only for == and the four inequalities.
func flip(op token.Token) token.Token {
	switch op {
	case token.EQL:
		return token.EQL // (same)
	case token.GEQ:
		return token.LEQ
	case token.GTR:
		return token.LSS
	case token.LEQ:
		return token.GEQ
	case token.LSS:
		return token.GTR
	}
	return op
}

// isBeforeSlice reports whether the SliceExpr is of the form s[:i] or s[0:i].
func isBeforeSlice(info *types.Info, ek edge.Kind, slice *ast.SliceExpr) bool {
	return ek == edge.SliceExpr_High && (slice.Low == nil || isZeroIntConst(info, slice.Low))
}

// constSubstrLen returns the constant length of substr, or -1 if unknown.
func constSubstrLen(info *types.Info, substr ast.Expr) int {
	// Handle len([]byte(substr))
	if call, ok := substr.(*ast.CallExpr); ok {
		tv := info.Types[call.Fun]
		if tv.IsType() && types.Identical(tv.Type, byteSliceType) {
			// Only one arg in []byte conversion.
			substr = call.Args[0]
		}
	}
	substrVal := info.Types[substr].Value
	if substrVal != nil {
		switch substrVal.Kind() {
		case constant.String:
			return len(constant.StringVal(substrVal))
		case constant.Int:
			// constant.Value is a byte literal, e.g. bytes.IndexByte(_, 'a')
			// or a numeric byte literal, e.g. bytes.IndexByte(_, 65)
			// ([]byte(rune) is not legal.)
			return 1
		}
	}
	return -1
}

// isAfterSlice reports whether the SliceExpr is of the form s[i+len(substr):],
// or s[i + k:] where k is a const is equal to len(substr).
func isAfterSlice(info *types.Info, ek edge.Kind, slice *ast.SliceExpr, substr ast.Expr) bool {
	lowExpr, ok := slice.Low.(*ast.BinaryExpr)
	if !ok || slice.High != nil {
		return false
	}
	// Returns true if the expression is a call to len(substr).
	isLenCall := func(expr ast.Expr) bool {
		call, ok := expr.(*ast.CallExpr)
		if !ok || len(call.Args) != 1 {
			return false
		}
		return sameObject(info, substr, call.Args[0]) && typeutil.Callee(info, call) == builtinLen
	}

	substrLen := constSubstrLen(info, substr)

	switch ek {
	case edge.BinaryExpr_X:
		kVal := info.Types[lowExpr.Y].Value
		if kVal == nil {
			// i + len(substr)
			return lowExpr.Op == token.ADD && isLenCall(lowExpr.Y)
		} else {
			// i + k
			kInt, ok := constant.Int64Val(kVal)
			return ok && substrLen == int(kInt)
		}
	case edge.BinaryExpr_Y:
		kVal := info.Types[lowExpr.X].Value
		if kVal == nil {
			// len(substr) + i
			return lowExpr.Op == token.ADD && isLenCall(lowExpr.X)
		} else {
			// k + i
			kInt, ok := constant.Int64Val(kVal)
			return ok && substrLen == int(kInt)
		}
	}
	return false
}

// isSliceIndexGuarded reports whether a use of the index variable i (at the given cursor)
// inside a slice expression is dominated by a nonnegative guard.
// A use is considered guarded if any of the following are true:
//   - It is inside the Body of an IfStmt whose condition is a nonnegative check on i.
//   - It is inside the Else of an IfStmt whose condition is a negative check on i.
//   - It is preceded (in the same block) by an IfStmt whose condition is a
//     negative check on i with a terminating body (e.g., early return).
//
// Conversely, a use is immediately rejected if:
//   - It is inside the Body of an IfStmt whose condition is a negative check on i.
//   - It is inside the Else of an IfStmt whose condition is a nonnegative check on i.
//
// We have already checked (see [hasModifyingUses]) that there are no
// intervening uses (incl. via aliases) of i that might alter its value.
func isSliceIndexGuarded(info *types.Info, cur inspector.Cursor, iObj types.Object) bool {
	for anc := range cur.Enclosing() {
		switch anc.ParentEdgeKind() {
		case edge.IfStmt_Body, edge.IfStmt_Else:
			ifStmt := anc.Parent().Node().(*ast.IfStmt)
			check := condChecksIdx(info, ifStmt.Cond, iObj)
			if anc.ParentEdgeKind() == edge.IfStmt_Else {
				check = -check
			}
			if check > 0 {
				return true // inside nonnegative-guarded block (i >= 0 here)
			}
			if check < 0 {
				return false // inside negative-guarded block (i < 0 here)
			}
		case edge.BlockStmt_List:
			// Check preceding siblings for early-return negative checks.
			for sib, ok := anc.PrevSibling(); ok; sib, ok = sib.PrevSibling() {
				ifStmt, ok := sib.Node().(*ast.IfStmt)
				if ok && condChecksIdx(info, ifStmt.Cond, iObj) < 0 && bodyTerminates(ifStmt.Body) {
					return true // preceded by early-return negative check
				}
			}
		case edge.FuncDecl_Body, edge.FuncLit_Body:
			return false // stop at function boundary
		}
	}
	return false
}

// condChecksIdx reports whether cond is a BinaryExpr that checks
// the index variable iObj for negativity or non-negativity.
// Returns -1 for negative (e.g. i < 0), +1 for nonnegative (e.g. i >= 0), 0 otherwise.
func condChecksIdx(info *types.Info, cond ast.Expr, iObj types.Object) int {
	binExpr, ok := cond.(*ast.BinaryExpr)
	if !ok {
		return 0
	}
	return checkIdxComparison(info, binExpr, iObj)
}

// bodyTerminates reports whether the given block statement unconditionally
// terminates execution (via return, break, continue, or goto).
func bodyTerminates(block *ast.BlockStmt) bool {
	if len(block.List) == 0 {
		return false
	}
	last := block.List[len(block.List)-1]
	switch last.(type) {
	case *ast.ReturnStmt, *ast.BranchStmt:
		return true // return, break, continue, goto
	}
	return false
}

// sameObject reports whether we know that the expressions resolve to the same object.
func sameObject(info *types.Info, expr1, expr2 ast.Expr) bool {
	if ident1, ok := expr1.(*ast.Ident); ok {
		if ident2, ok := expr2.(*ast.Ident); ok {
			uses1, ok1 := info.Uses[ident1]
			uses2, ok2 := info.Uses[ident2]
			return ok1 && ok2 && uses1 == uses2
		}
	}
	return false
}


================================================
FILE: go/analysis/passes/modernize/stringscutprefix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var StringsCutPrefixAnalyzer = &analysis.Analyzer{
	Name: "stringscutprefix",
	Doc:  analyzerutil.MustExtractDoc(doc, "stringscutprefix"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: stringscutprefix,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscutprefix",
}

// stringscutprefix offers a fix to replace an if statement which
// calls to the 2 patterns below with strings.CutPrefix or strings.CutSuffix.
//
// Patterns:
//
//  1. if strings.HasPrefix(s, pre) { use(strings.TrimPrefix(s, pre) }
//     =>
//     if after, ok := strings.CutPrefix(s, pre); ok { use(after) }
//
//  2. if after := strings.TrimPrefix(s, pre); after != s { use(after) }
//     =>
//     if after, ok := strings.CutPrefix(s, pre); ok { use(after) }
//
// Similar patterns apply for CutSuffix.
//
// The use must occur within the first statement of the block, and the offered fix
// only replaces the first occurrence of strings.TrimPrefix/TrimSuffix.
//
// Variants:
// - bytes.HasPrefix/HasSuffix usage as pattern 1.
func stringscutprefix(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo

		stringsTrimPrefix = index.Object("strings", "TrimPrefix")
		bytesTrimPrefix   = index.Object("bytes", "TrimPrefix")
		stringsTrimSuffix = index.Object("strings", "TrimSuffix")
		bytesTrimSuffix   = index.Object("bytes", "TrimSuffix")
	)
	if !index.Used(stringsTrimPrefix, bytesTrimPrefix, stringsTrimSuffix, bytesTrimSuffix) {
		return nil, nil
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_20) {
		for curIfStmt := range curFile.Preorder((*ast.IfStmt)(nil)) {
			ifStmt := curIfStmt.Node().(*ast.IfStmt)

			// pattern1
			if call, ok := ifStmt.Cond.(*ast.CallExpr); ok && ifStmt.Init == nil && len(ifStmt.Body.List) > 0 {

				obj := typeutil.Callee(info, call)
				if !typesinternal.IsFunctionNamed(obj, "strings", "HasPrefix", "HasSuffix") &&
					!typesinternal.IsFunctionNamed(obj, "bytes", "HasPrefix", "HasSuffix") {
					continue
				}
				isPrefix := strings.HasSuffix(obj.Name(), "Prefix")

				// Replace the first occurrence of strings.TrimPrefix(s, pre) in the first statement only,
				// but not later statements in case s or pre are modified by intervening logic (ditto Suffix).
				firstStmt := curIfStmt.Child(ifStmt.Body).Child(ifStmt.Body.List[0])
				for curCall := range firstStmt.Preorder((*ast.CallExpr)(nil)) {
					call1 := curCall.Node().(*ast.CallExpr)
					obj1 := typeutil.Callee(info, call1)
					// bytesTrimPrefix or stringsTrimPrefix might be nil if the file doesn't import it,
					// so we need to ensure the obj1 is not nil otherwise the call1 is not TrimPrefix and cause a panic (ditto Suffix).
					if obj1 == nil ||
						obj1 != stringsTrimPrefix && obj1 != bytesTrimPrefix &&
							obj1 != stringsTrimSuffix && obj1 != bytesTrimSuffix {
						continue
					}

					isPrefix1 := strings.HasSuffix(obj1.Name(), "Prefix")
					var cutFuncName, varName, message, fixMessage string
					if isPrefix && isPrefix1 {
						cutFuncName = "CutPrefix"
						varName = "after"
						message = "HasPrefix + TrimPrefix can be simplified to CutPrefix"
						fixMessage = "Replace HasPrefix/TrimPrefix with CutPrefix"
					} else if !isPrefix && !isPrefix1 {
						cutFuncName = "CutSuffix"
						varName = "before"
						message = "HasSuffix + TrimSuffix can be simplified to CutSuffix"
						fixMessage = "Replace HasSuffix/TrimSuffix with CutSuffix"
					} else {
						continue
					}

					// Have: if strings.HasPrefix(s0, pre0) { ...strings.TrimPrefix(s, pre)... } (ditto Suffix)
					var (
						s0   = call.Args[0]
						pre0 = call.Args[1]
						s    = call1.Args[0]
						pre  = call1.Args[1]
					)

					// check whether the obj1 uses the exact the same argument with strings.HasPrefix
					// shadow variables won't be valid because we only access the first statement (ditto Suffix).
					if astutil.EqualSyntax(s0, s) && astutil.EqualSyntax(pre0, pre) {
						after := refactor.FreshName(info.Scopes[ifStmt], ifStmt.Pos(), varName)
						prefix, importEdits := refactor.AddImport(
							info,
							curFile.Node().(*ast.File),
							obj1.Pkg().Name(),
							obj1.Pkg().Path(),
							cutFuncName,
							call.Pos(),
						)
						okVarName := refactor.FreshName(info.Scopes[ifStmt], ifStmt.Pos(), "ok")
						pass.Report(analysis.Diagnostic{
							// highlight at HasPrefix call (ditto Suffix).
							Pos:     call.Pos(),
							End:     call.End(),
							Message: message,
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: fixMessage,
								// if              strings.HasPrefix(s, pre)     { use(strings.TrimPrefix(s, pre)) }
								//    ------------ -----------------        -----      --------------------------
								// if after, ok := strings.CutPrefix(s, pre); ok { use(after)                      }
								// (ditto Suffix)
								TextEdits: append(importEdits, []analysis.TextEdit{
									{
										Pos:     call.Fun.Pos(),
										End:     call.Fun.Pos(),
										NewText: fmt.Appendf(nil, "%s, %s :=", after, okVarName),
									},
									{
										Pos:     call.Fun.Pos(),
										End:     call.Fun.End(),
										NewText: fmt.Appendf(nil, "%s%s", prefix, cutFuncName),
									},
									{
										Pos:     call.End(),
										End:     call.End(),
										NewText: fmt.Appendf(nil, "; %s ", okVarName),
									},
									{
										Pos:     call1.Pos(),
										End:     call1.End(),
										NewText: []byte(after),
									},
								}...),
							}}},
						)
						break
					}
				}
			}

			// pattern2
			if bin, ok := ifStmt.Cond.(*ast.BinaryExpr); ok &&
				bin.Op == token.NEQ &&
				ifStmt.Init != nil &&
				isSimpleAssign(ifStmt.Init) {
				assign := ifStmt.Init.(*ast.AssignStmt)
				if call, ok := assign.Rhs[0].(*ast.CallExpr); ok && assign.Tok == token.DEFINE {
					lhs := assign.Lhs[0]
					obj := typeutil.Callee(info, call)

					if obj == nil ||
						obj != stringsTrimPrefix && obj != bytesTrimPrefix && obj != stringsTrimSuffix && obj != bytesTrimSuffix {
						continue
					}

					isPrefix1 := strings.HasSuffix(obj.Name(), "Prefix")
					var cutFuncName, message, fixMessage string
					if isPrefix1 {
						cutFuncName = "CutPrefix"
						message = "TrimPrefix can be simplified to CutPrefix"
						fixMessage = "Replace TrimPrefix with CutPrefix"
					} else {
						cutFuncName = "CutSuffix"
						message = "TrimSuffix can be simplified to CutSuffix"
						fixMessage = "Replace TrimSuffix with CutSuffix"
					}

					if astutil.EqualSyntax(lhs, bin.X) && astutil.EqualSyntax(call.Args[0], bin.Y) ||
						(astutil.EqualSyntax(lhs, bin.Y) && astutil.EqualSyntax(call.Args[0], bin.X)) {
						okVarName := freshName(info, index, info.Scopes[ifStmt], ifStmt.Pos(), curIfStmt, curIfStmt, token.NoPos, "ok")
						// Have one of:
						//   if rest := TrimPrefix(s, prefix); rest != s { (ditto Suffix)
						//   if rest := TrimPrefix(s, prefix); s != rest { (ditto Suffix)

						// We use AddImport not to add an import (since it exists already)
						// but to compute the correct prefix in the dot-import case.
						prefix, importEdits := refactor.AddImport(
							info,
							curFile.Node().(*ast.File),
							obj.Pkg().Name(),
							obj.Pkg().Path(),
							cutFuncName,
							call.Pos(),
						)

						pass.Report(analysis.Diagnostic{
							// highlight from the init and the condition end.
							Pos:     ifStmt.Init.Pos(),
							End:     ifStmt.Cond.End(),
							Message: message,
							SuggestedFixes: []analysis.SuggestedFix{{
								Message: fixMessage,
								// if x     := strings.TrimPrefix(s, pre); x != s ...
								//     ----            ----------          ------
								// if x, ok := strings.CutPrefix (s, pre); ok     ...
								// (ditto Suffix)
								TextEdits: append(importEdits, []analysis.TextEdit{
									{
										Pos:     assign.Lhs[0].End(),
										End:     assign.Lhs[0].End(),
										NewText: fmt.Appendf(nil, ", %s", okVarName),
									},
									{
										Pos:     call.Fun.Pos(),
										End:     call.Fun.End(),
										NewText: fmt.Appendf(nil, "%s%s", prefix, cutFuncName),
									},
									{
										Pos:     ifStmt.Cond.Pos(),
										End:     ifStmt.Cond.End(),
										NewText: []byte(okVarName),
									},
								}...),
							}},
						})
					}
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/stringsseq.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var StringsSeqAnalyzer = &analysis.Analyzer{
	Name: "stringsseq",
	Doc:  analyzerutil.MustExtractDoc(doc, "stringsseq"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: stringsseq,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringsseq",
}

// stringsseq offers a fix to replace a call to strings.Split with
// SplitSeq or strings.Fields with FieldsSeq
// when it is the operand of a range loop, either directly:
//
//	for _, line := range strings.Split() {...}
//
// or indirectly, if the variable's sole use is the range statement:
//
//	lines := strings.Split()
//	for _, line := range lines {...}
//
// Variants:
// - bytes.SplitSeq
// - bytes.FieldsSeq
func stringsseq(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo

		stringsSplit  = index.Object("strings", "Split")
		stringsFields = index.Object("strings", "Fields")
		bytesSplit    = index.Object("bytes", "Split")
		bytesFields   = index.Object("bytes", "Fields")
	)
	if !index.Used(stringsSplit, stringsFields, bytesSplit, bytesFields) {
		return nil, nil
	}

	for curFile := range filesUsingGoVersion(pass, versions.Go1_24) {
		for curRange := range curFile.Preorder((*ast.RangeStmt)(nil)) {
			rng := curRange.Node().(*ast.RangeStmt)

			// Reject "for i, line := ..." since SplitSeq is not an iter.Seq2.
			// (We require that i is blank.)
			if id, ok := rng.Key.(*ast.Ident); ok && id.Name != "_" {
				continue
			}

			// Find the call operand of the range statement,
			// whether direct or indirect.
			call, ok := rng.X.(*ast.CallExpr)
			if !ok {
				if id, ok := rng.X.(*ast.Ident); ok {
					if v, ok := info.Uses[id].(*types.Var); ok {
						if ek, idx := curRange.ParentEdge(); ek == edge.BlockStmt_List && idx > 0 {
							curPrev, _ := curRange.PrevSibling()
							if assign, ok := curPrev.Node().(*ast.AssignStmt); ok &&
								assign.Tok == token.DEFINE &&
								len(assign.Lhs) == 1 &&
								len(assign.Rhs) == 1 &&
								info.Defs[assign.Lhs[0].(*ast.Ident)] == v &&
								soleUseIs(index, v, id) {
								// Have:
								//    lines := ...
								//    for _, line := range lines {...}
								// and no other uses of lines.
								call, _ = assign.Rhs[0].(*ast.CallExpr)
							}
						}
					}
				}
			}

			if call != nil {
				var edits []analysis.TextEdit
				if rng.Key != nil {
					// Delete (blank) RangeStmt.Key:
					//  for _, line := -> for line :=
					//  for _, _    := -> for
					//  for _       := -> for
					end := rng.Range
					if rng.Value != nil {
						end = rng.Value.Pos()
					}
					edits = append(edits, analysis.TextEdit{
						Pos: rng.Key.Pos(),
						End: end,
					})
				}

				sel, ok := call.Fun.(*ast.SelectorExpr)
				if !ok {
					continue
				}

				switch obj := typeutil.Callee(info, call); obj {
				case stringsSplit, stringsFields, bytesSplit, bytesFields:
					oldFnName := obj.Name()
					seqFnName := fmt.Sprintf("%sSeq", oldFnName)
					pass.Report(analysis.Diagnostic{
						Pos:     sel.Pos(),
						End:     sel.End(),
						Message: fmt.Sprintf("Ranging over %s is more efficient", seqFnName),
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: fmt.Sprintf("Replace %s with %s", oldFnName, seqFnName),
							TextEdits: append(edits, analysis.TextEdit{
								Pos:     sel.Sel.Pos(),
								End:     sel.Sel.End(),
								NewText: []byte(seqFnName)}),
						}},
					})
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/any/any.go
================================================
package any

func _(x interface{}) {} // want "interface{} can be replaced by any"

func _() {
	var x interface{} // want "interface{} can be replaced by any"
	const any = 1
	var y interface{} // nope: any is shadowed here
	_, _ = x, y
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/any/any.go.golden
================================================
package any

func _(x any) {} // want "interface{} can be replaced by any"

func _() {
	var x any // want "interface{} can be replaced by any"
	const any = 1
	var y interface{} // nope: any is shadowed here
	_, _ = x, y
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/any/generated.go
================================================
// Code generated by hand. DO NOT EDIT.

package any

func _(x interface{}) {} // want "interface{} can be replaced by any"

func _() {
	var x interface{} // want "interface{} can be replaced by any"
	const any = 1
	var y interface{} // nope: any is shadowed here
	_, _ = x, y
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/any/generated.go.golden
================================================
// Code generated by hand. DO NOT EDIT.

package any

func _(x interface{}) {} // want "interface{} can be replaced by any"

func _() {
	var x interface{} // want "interface{} can be replaced by any"
	const any = 1
	var y interface{} // nope: any is shadowed here
	_, _ = x, y
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/appendclipped/appendclipped.go
================================================
package appendclipped

import (
	"os"
	"slices"
)

type (
	Bytes  []byte
	Bytes2 []byte
)

func _(s, other []string) {
	print(append([]string{}, s...))              // want "Replace append with slices.Clone"
	print(append([]string(nil), s...))           // want "Replace append with slices.Clone"
	print(append(Bytes(nil), Bytes{1, 2, 3}...)) // want "Replace append with slices.Clone"
	print(append(other[:0:0], s...))             // want "Replace append with slices.Clone"
	print(append(other[:0:0], os.Environ()...))  // want "Redundant clone of os.Environ()"
	print(append(other[:0], s...))               // nope: intent may be to mutate other

	print(append(append(append([]string{}, s...), other...), other...))             // want "Replace append with slices.Concat"
	print(append(append(append([]string(nil), s...), other...), other...))          // want "Replace append with slices.Concat"
	print(append(append(Bytes(nil), Bytes{1, 2, 3}...), Bytes{4, 5, 6}...))         // want "Replace append with slices.Concat"
	print(append(append(append(other[:0:0], s...), other...), other...))            // want "Replace append with slices.Concat"
	print(append(append(append(other[:0:0], os.Environ()...), other...), other...)) // want "Replace append with slices.Concat"
	print(append(append(other[:len(other):len(other)], s...), other...))            // want "Replace append with slices.Concat"
	print(append(append(slices.Clip(other), s...), other...))                       // want "Replace append with slices.Concat"
	print(append(append(append(other[:0], s...), other...), other...))              // nope: intent may be to mutate other
}

var (
	_ Bytes  = append(Bytes(nil), []byte(nil)...) // nope: correct fix requires Clone[Bytes] (#73661)
	_ Bytes  = append([]byte(nil), Bytes(nil)...) // nope: correct fix requires Clone[Bytes] (#73661)
	_ Bytes2 = append([]byte(nil), Bytes(nil)...) // nope: correct fix requires Clone[Bytes2] (#73661)
)


================================================
FILE: go/analysis/passes/modernize/testdata/src/appendclipped/appendclipped.go.golden
================================================
package appendclipped

import (
	"os"
	"slices"
)

type (
	Bytes	[]byte
	Bytes2  []byte
)

func _(s, other []string) {
	print(slices.Clone(s))              // want "Replace append with slices.Clone"
	print(slices.Clone(s))              // want "Replace append with slices.Clone"
	print(slices.Clone(Bytes{1, 2, 3})) // want "Replace append with slices.Clone"
	print(slices.Clone(s))              // want "Replace append with slices.Clone"
	print(os.Environ())                 // want "Redundant clone of os.Environ()"
	print(append(other[:0], s...))      // nope: intent may be to mutate other

	print(slices.Concat(s, other, other))                              // want "Replace append with slices.Concat"
	print(slices.Concat(s, other, other))                              // want "Replace append with slices.Concat"
	print(slices.Concat(Bytes{1, 2, 3}, Bytes{4, 5, 6}))               // want "Replace append with slices.Concat"
	print(slices.Concat(s, other, other))                              // want "Replace append with slices.Concat"
	print(slices.Concat(os.Environ(), other, other))                   // want "Replace append with slices.Concat"
	print(slices.Concat(other, s, other))                              // want "Replace append with slices.Concat"
	print(slices.Concat(other, s, other))                              // want "Replace append with slices.Concat"
	print(append(append(append(other[:0], s...), other...), other...)) // nope: intent may be to mutate other
}

var (
	_ Bytes  = append(Bytes(nil), []byte(nil)...) // nope: correct fix requires Clone[Bytes] (#73661)
	_ Bytes  = append([]byte(nil), Bytes(nil)...) // nope: correct fix requires Clone[Bytes] (#73661)
	_ Bytes2 = append([]byte(nil), Bytes(nil)...) // nope: correct fix requires Clone[Bytes2] (#73661)
)


================================================
FILE: go/analysis/passes/modernize/testdata/src/appendclipped/bytesclone.go
================================================
package appendclipped

import (
	"bytes"
)

var _ bytes.Buffer

func _(b []byte) {
	print(append([]byte{}, b...)) // want "Replace append with bytes.Clone"
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/appendclipped/bytesclone.go.golden
================================================
package appendclipped

import (
	"bytes"
)

var _ bytes.Buffer

func _(b []byte) {
	print(bytes.Clone(b)) // want "Replace append with bytes.Clone"
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/atomic.go
================================================
package atomic

import (
	"log"
	"sync/atomic"
)

type X struct {
	x int32 // want "var x int32 may be simplified using atomic.Int32"
}

type Z struct {
	y int64 // want "var y int64 may be simplified using atomic.Int64"
	z int64
}

func (wrapper *Z) fix() {
	var x int32 // want "var x int32 may be simplified using atomic.Int32"
	for range 100 {
		go atomic.AddInt32(&x, 1)
	}

	var x2 int32 = 5 // nope: can't assign an int to an atomic.Int32
	for range 100 {
		go atomic.AddInt32(&x2, 1)
	}

	var y X
	for range 100 {
		go atomic.CompareAndSwapInt32(&y.x, 2, 3)
	}

	atomic.CompareAndSwapInt64(&wrapper.y, 2, 3)

	var z int32
	_ = z
	if z == 0 { // nope: cannot rewrite rvalue use (unsynchronized load)
		go atomic.LoadInt32(&z)
		log.Print(z)
	}
}

type Y int32

func (y Y) dontfix(x int32) (result int32) {
	atomic.AddInt32(&x, 1)           // nope - v is a type param
	atomic.StoreInt32(&result, 100)  // nope - v is a return value
	atomic.AddInt32((*int32)(&y), 1) // nope - v is a receiver var
	w := Z{
		z: 1,
	}
	atomic.AddInt64(&w.z, 1) // nope - cannot fix initial value assignment
	return
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/atomic.go.golden
================================================
package atomic

import (
	"log"
	"sync/atomic"
)

type X struct {
	x atomic.Int32 // want "var x int32 may be simplified using atomic.Int32"
}

type Z struct {
	y atomic.Int64 // want "var y int64 may be simplified using atomic.Int64"
	z int64
}

func (wrapper *Z) fix() {
	var x atomic.Int32 // want "var x int32 may be simplified using atomic.Int32"
	for range 100 {
		go x.Add(1)
	}

	var x2 int32 = 5 // nope: can't assign an int to an atomic.Int32
	for range 100 {
		go atomic.AddInt32(&x2, 1)
	}

	var y X
	for range 100 {
		go y.x.CompareAndSwap(2, 3)
	}

	wrapper.y.CompareAndSwap(2, 3)

	var z int32
	_ = z
	if z == 0 { // nope: cannot rewrite rvalue use (unsynchronized load)
		go atomic.LoadInt32(&z)
		log.Print(z)
	}
}

type Y int32

func (y Y) dontfix(x int32) (result int32) {
	atomic.AddInt32(&x, 1)           // nope - v is a type param
	atomic.StoreInt32(&result, 100)  // nope - v is a return value
	atomic.AddInt32((*int32)(&y), 1) // nope - v is a receiver var
	w := Z{
		z: 1,
	}
	atomic.AddInt64(&w.z, 1) // nope - cannot fix initial value assignment
	return
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/atomic_shadow.go
================================================
package atomic

import myatomic "sync/atomic"

func _() {
	var x int32 // want "var x int32 may be simplified using atomic.Int32"
	for range 100 {
		go myatomic.AddInt32(&x, 1)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/atomic_shadow.go.golden
================================================
package atomic

import myatomic "sync/atomic"

func _() {
	var x myatomic.Int32 // want "var x int32 may be simplified using atomic.Int32"
	for range 100 {
		go x.Add(1)
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/go118/atomic_go118.go
================================================
//go:build !go1.19

package go118

import "sync/atomic"

func _() {
	var x int32 // AddInt32 not available until go1.19
	for range 100 {
		go atomic.AddInt32(&x, 1)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/go118/atomic_go118.go.golden
================================================
//go:build !go1.19

package go118

import "sync/atomic"

func _() {
	var x int32 // AddInt32 not available until go1.19
	for range 100 {
		go atomic.AddInt32(&x, 2)
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/go120/atomic_go120.go
================================================
//go:build !go1.21

package go120

import "sync/atomic"

func _() {
	var x int32 // AndInt32 not available until go1.23
	for range 100 {
		go atomic.AndInt32(&x, 1)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/go120/atomic_go120.go.golden
================================================
//go:build !go1.21

package go120

import "sync/atomic"

func _() {
	var x int32 // AndInt32 not available until go1.23
	for range 100 {
		go atomic.AndInt32(&x, 1)
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/ignored/atomic.go
================================================
package ignored

import (
	"sync/atomic"
)

var x int32 // don't fix - package has ignored files

func _() {
	for range 100 {
		go atomic.AddInt32(&x, 1)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/ignored/atomic.go.golden
================================================
package ignored

import (
	"sync/atomic"
)

var x int32 // don't fix - package has ignored files

func _() {
	for range 100 {
		go atomic.AddInt32(&x, 1)
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/atomictypes/ignored/atomic_ignored.go
================================================
//go:build !go1.19

package ignored

import "sync/atomic"

func _() {
	for range 100 {
		go atomic.AddInt32(&x, 1)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/bloop/bloop.go
================================================
package bloop


================================================
FILE: go/analysis/passes/modernize/testdata/src/bloop/bloop_test.go
================================================
//go:build go1.24

package bloop

import (
	"sync"
	"testing"
)

func BenchmarkA(b *testing.B) {
	println("slow")
	b.ResetTimer()

	for range b.N { // want "b.N can be modernized using b.Loop.."
	}
}

func BenchmarkB(b *testing.B) {
	// setup
	{
		b.StopTimer()
		println("slow")
		b.StartTimer()
	}

	for i := range b.N { // Nope. Should we change this to "for i := 0; b.Loop(); i++"?
		print(i)
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkC(b *testing.B) {
	// setup
	{
		b.StopTimer()
		println("slow")
		b.StartTimer()
	}

	for i := 0; i < b.N; i++ { // want "b.N can be modernized using b.Loop.."
		println("no uses of i")
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkD(b *testing.B) {
	for i := 0; i < b.N; i++ { // want "b.N can be modernized using b.Loop.."
		println(i)
	}
}

func BenchmarkE(b *testing.B) {
	b.Run("sub", func(b *testing.B) {
		b.StopTimer() // not deleted
		println("slow")
		b.StartTimer() // not deleted

		// ...
	})
	b.ResetTimer()

	for i := 0; i < b.N; i++ { // want "b.N can be modernized using b.Loop.."
		println("no uses of i")
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkF(b *testing.B) {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < b.N; i++ { // nope: b.N accessed from a FuncLit
		}
	}()
	wg.Wait()
}

func BenchmarkG(b *testing.B) {
	var wg sync.WaitGroup
	poster := func() {
		for i := 0; i < b.N; i++ { // nope: b.N accessed from a FuncLit
		}
		wg.Done()
	}
	wg.Add(2)
	for i := 0; i < 2; i++ {
		go poster()
	}
	wg.Wait()
}

func BenchmarkH(b *testing.B) {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		for range b.N { // nope: b.N accessed from a FuncLit
		}
	}()
	wg.Wait()
}

func BenchmarkI(b *testing.B) {
	for i := 0; i < b.N; i++ { // nope: b.N accessed more than once in benchmark
	}
	for i := 0; i < b.N; i++ { // nope: b.N accessed more than once in benchmark
	}
}

func BenchmarkJ(b *testing.B) {
	var wg sync.WaitGroup
	ch := make(chan int, 10)
	wg.Add(1)
	go func() {
		for i := 0; i < b.N; i++ {
			<-ch
		}
		wg.Done()
	}()
	b.ResetTimer()
	for i := 0; i < b.N; i++ { // nope: multiple b.N loops in same function
		ch <- i
	}
	b.StopTimer()
	wg.Wait()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/bloop/bloop_test.go.golden
================================================
//go:build go1.24

package bloop

import (
	"sync"
	"testing"
)

func BenchmarkA(b *testing.B) {
	println("slow")

	for b.Loop() { // want "b.N can be modernized using b.Loop.."
	}
}

func BenchmarkB(b *testing.B) {
	// setup
	{
		b.StopTimer()
		println("slow")
		b.StartTimer()
	}

	for i := range b.N { // Nope. Should we change this to "for i := 0; b.Loop(); i++"?
		print(i)
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkC(b *testing.B) {
	// setup
	{

		println("slow")

	}

	for b.Loop() { // want "b.N can be modernized using b.Loop.."
		println("no uses of i")
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkD(b *testing.B) {
	for i := 0; b.Loop(); i++ { // want "b.N can be modernized using b.Loop.."
		println(i)
	}
}

func BenchmarkE(b *testing.B) {
	b.Run("sub", func(b *testing.B) {
		b.StopTimer() // not deleted
		println("slow")
		b.StartTimer() // not deleted

		// ...
	})

	for b.Loop() { // want "b.N can be modernized using b.Loop.."
		println("no uses of i")
	}

	b.StopTimer()
	println("slow")
}

func BenchmarkF(b *testing.B) {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < b.N; i++ { // nope: b.N accessed from a FuncLit
		}
	}()
	wg.Wait()
}

func BenchmarkG(b *testing.B) {
	var wg sync.WaitGroup
	poster := func() {
		for i := 0; i < b.N; i++ { // nope: b.N accessed from a FuncLit
		}
		wg.Done()
	}
	wg.Add(2)
	for i := 0; i < 2; i++ {
		go poster()
	}
	wg.Wait()
}

func BenchmarkH(b *testing.B) {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		for range b.N { // nope: b.N accessed from a FuncLit
		}
	}()
	wg.Wait()
}

func BenchmarkI(b *testing.B) {
	for i := 0; i < b.N; i++ { // nope: b.N accessed more than once in benchmark
	}
	for i := 0; i < b.N; i++ { // nope: b.N accessed more than once in benchmark
	}
}

func BenchmarkJ(b *testing.B) {
	var wg sync.WaitGroup
	ch := make(chan int, 10)
	wg.Add(1)
	go func() {
		for i := 0; i < b.N; i++ {
			<-ch
		}
		wg.Done()
	}()
	b.ResetTimer()
	for i := 0; i < b.N; i++ { // nope: multiple b.N loops in same function
		ch <- i
	}
	b.StopTimer()
	wg.Wait()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/errorsastype/dotimport/a.go
================================================
package errorsastype

import (
	. "errors"
	"os"
)

func _(err error) {
	var patherr *os.PathError
	if As(err, &patherr) { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
		print(patherr)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/errorsastype/dotimport/a.go.golden
================================================
package errorsastype

import (
	. "errors"
	"os"
)

func _(err error) {
	if patherr, ok := AsType[*os.PathError](err); ok { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
		print(patherr)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/errorsastype/errorsastype.go
================================================
package errorsastype

import (
	"errors"
	"os"
)

func _(err error) {
	{
		var patherr *os.PathError
		if errors.As(err, &patherr) { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
	}
	{
		var patherr *os.PathError
		print("not a use of patherr")
		if errors.As(err, &patherr) { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
		print("also not a use of patherr")
	}
	{
		var patherr *os.PathError
		print(patherr)
		if errors.As(err, &patherr) { // nope: patherr is used outside scope of if
			print(patherr)
		}
	}
	{
		var patherr *os.PathError
		if errors.As(err, &patherr) { // nope: patherr is used outside scope of if
			print(patherr)
		}
		print(patherr)
	}

	// Test of 'ok' var shadowing/freshness.
	const ok = 1
	{
		var patherr *os.PathError
		if errors.As(err, &patherr) { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
	}
	{
		var patherr *os.PathError
		if errors.As(err, &patherr) { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr, ok)
		}
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/errorsastype/errorsastype.go.golden
================================================
package errorsastype

import (
	"errors"
	"os"
)

func _(err error) {
	{
		if patherr, ok := errors.AsType[*os.PathError](err); ok { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
	}
	{
		print("not a use of patherr")
		if patherr, ok := errors.AsType[*os.PathError](err); ok { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
		print("also not a use of patherr")
	}
	{
		var patherr *os.PathError
		print(patherr)
		if errors.As(err, &patherr) { // nope: patherr is used outside scope of if
			print(patherr)
		}
	}
	{
		var patherr *os.PathError
		if errors.As(err, &patherr) { // nope: patherr is used outside scope of if
			print(patherr)
		}
		print(patherr)
	}

	// Test of 'ok' var shadowing/freshness.
	const ok = 1
	{
		if patherr, ok := errors.AsType[*os.PathError](err); ok { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr)
		}
	}
	{
		if patherr, ok0 := errors.AsType[*os.PathError](err); ok0 { // want `errors.As can be simplified using AsType\[\*os.PathError\]`
			print(patherr, ok)
		}
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/fieldsseq/fieldsseq.go
================================================
//go:build go1.24

package fieldsseq

import (
	"bytes"
	"strings"
)

func _() {
	for _, line := range strings.Fields("") { // want "Ranging over FieldsSeq is more efficient"
		println(line)
	}
	for i, line := range strings.Fields("") { // nope: uses index var
		println(i, line)
	}
	for i, _ := range strings.Fields("") { // nope: uses index var
		println(i)
	}
	for i := range strings.Fields("") { // nope: uses index var
		println(i)
	}
	for _ = range strings.Fields("") { // want "Ranging over FieldsSeq is more efficient"
	}
	for range strings.Fields("") { // want "Ranging over FieldsSeq is more efficient"
	}
	for range bytes.Fields(nil) { // want "Ranging over FieldsSeq is more efficient"
	}
	{
		lines := strings.Fields("") // want "Ranging over FieldsSeq is more efficient"
		for _, line := range lines {
			println(line)
		}
	}
	{
		lines := strings.Fields("") // nope: lines is used not just by range
		for _, line := range lines {
			println(line)
		}
		println(lines)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/fieldsseq/fieldsseq.go.golden
================================================
//go:build go1.24

package fieldsseq

import (
	"bytes"
	"strings"
)

func _() {
	for line := range strings.FieldsSeq("") { // want "Ranging over FieldsSeq is more efficient"
		println(line)
	}
	for i, line := range strings.Fields( "") { // nope: uses index var
		println(i, line)
	}
	for i, _ := range strings.Fields( "") { // nope: uses index var
		println(i)
	}
	for i := range strings.Fields( "") { // nope: uses index var
		println(i)
	}
	for range strings.FieldsSeq("") { // want "Ranging over FieldsSeq is more efficient"
	}
	for range strings.FieldsSeq("") { // want "Ranging over FieldsSeq is more efficient"
	}
	for range bytes.FieldsSeq(nil) { // want "Ranging over FieldsSeq is more efficient"
	}
	{
		lines := strings.FieldsSeq("") // want "Ranging over FieldsSeq is more efficient"
		for line := range lines {
			println(line)
		}
	}
	{
		lines := strings.Fields( "") // nope: lines is used not just by range
		for _, line := range lines {
			println(line)
		}
		println(lines)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/fieldsseq/fieldsseq_go123.go
================================================
package fieldsseq


================================================
FILE: go/analysis/passes/modernize/testdata/src/fmtappendf/fmtappendf.go
================================================
package fmtappendf

import (
	"fmt"
)

func two() string {
	return "two"
}

func bye() {
	_ = []byte(fmt.Sprintf("bye %d", 1)) // want "Replace .*Sprintf.* with fmt.Appendf"
}

func funcsandvars() {
	one := "one"
	_ = []byte(fmt.Sprintf("bye %d %s %s", 1, two(), one)) // want "Replace .*Sprintf.* with fmt.Appendf"
}

func typealias() {
	type b = byte
	type bt = []byte
	_ = []b(fmt.Sprintf("bye %d", 1)) // want "Replace .*Sprintf.* with fmt.Appendf"
	_ = bt(fmt.Sprintf("bye %d", 1))  // want "Replace .*Sprintf.* with fmt.Appendf"
}

func otherprints() {
	_ = []byte(fmt.Sprint("bye %d", 1))   // want "Replace .*Sprint.* with fmt.Append"
	_ = []byte(fmt.Sprintln("bye %d", 1)) // want "Replace .*Sprintln.* with fmt.Appendln"
}

func comma() {
	type S struct{ Bytes []byte }
	var _ = struct{ A S }{
		A: S{
			Bytes: []byte( // want "Replace .*Sprint.* with fmt.Appendf"
				fmt.Sprintf("%d", 0),
			),
		},
	}
	_ = []byte( // want "Replace .*Sprint.* with fmt.Appendf"
		fmt.Sprintf("%d", 0),
	)
}

func emptystring() {
	// empty string edge case only applies to Sprintf
	_ = []byte(fmt.Sprintln("")) // want "Replace .*Sprintln.* with fmt.Appendln"
	// nope - these return []byte{}, while the fmt.Append version returns nil
	_ = []byte(fmt.Sprint(""))
	_ = []byte(fmt.Sprintf("%s", ""))
	_ = []byte(fmt.Sprintf("%#s", ""))
	_ = []byte(fmt.Sprintf("%s%v", "", getString()))
	// conservatively omitting a suggested fix (ignoring precision and args)
	_ = []byte(fmt.Sprintf("%.0q", "notprinted"))
	_ = []byte(fmt.Sprintf("%v", "nonempty"))
	// has non-operation characters
	_ = []byte(fmt.Sprintf("%vother", "")) // want "Replace .*Sprint.* with fmt.Appendf"
}

func multiline() []byte {
	_ = []byte( // want "Replace .*Sprintf.* with fmt.Appendf"
		fmt.Sprintf("str %d", 1))

	return []byte( // want "Replace .*Sprintf.* with fmt.Appendf"
		fmt.Sprintf("str %d", 1),
	)
}

func getString() string {
	return ""
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/fmtappendf/fmtappendf.go.golden
================================================
package fmtappendf

import (
	"fmt"
)

func two() string {
	return "two"
}

func bye() {
	_ = fmt.Appendf(nil, "bye %d", 1) // want "Replace .*Sprintf.* with fmt.Appendf"
}

func funcsandvars() {
	one := "one"
	_ = fmt.Appendf(nil, "bye %d %s %s", 1, two(), one) // want "Replace .*Sprintf.* with fmt.Appendf"
}

func typealias() {
	type b = byte
	type bt = []byte
	_ = fmt.Appendf(nil, "bye %d", 1) // want "Replace .*Sprintf.* with fmt.Appendf"
	_ = fmt.Appendf(nil, "bye %d", 1) // want "Replace .*Sprintf.* with fmt.Appendf"
}

func otherprints() {
	_ = fmt.Append(nil, "bye %d", 1) // want "Replace .*Sprint.* with fmt.Append"
	_ = fmt.Appendln(nil, "bye %d", 1) // want "Replace .*Sprintln.* with fmt.Appendln"
}

func comma() {
	type S struct{ Bytes []byte }
	var _ = struct{ A S }{
		A: S{
			Bytes: fmt.Appendf(nil, "%d", 0),
		},
	}
	_ = fmt.Appendf(nil, "%d", 0)          
}

func emptystring() {
	// empty string edge case only applies to Sprintf
	_ = fmt.Appendln(nil, "")  // want "Replace .*Sprintln.* with fmt.Appendln"
	// nope - these return []byte{}, while the fmt.Append version returns nil
	_ = []byte(fmt.Sprint(""))
	_ = []byte(fmt.Sprintf("%s", ""))
	_ = []byte(fmt.Sprintf("%#s", ""))
	_ = []byte(fmt.Sprintf("%s%v", "", getString()))
	// conservatively omitting a suggested fix (ignoring precision and args)
	_ = []byte(fmt.Sprintf("%.0q", "notprinted"))
	_ = []byte(fmt.Sprintf("%v", "nonempty"))
	// has non-operation characters
	_ = fmt.Appendf(nil, "%vother", "") // want "Replace .*Sprint.* with fmt.Appendf"
}

func multiline() []byte {
	_ = fmt.Appendf(nil, "str %d", 1)

	return fmt.Appendf(nil, "str %d", 1)
}

func getString() string {
	return ""
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/forvar/forvar.go
================================================
package forvar

func _(m map[int]int, s []int) {
	// changed
	for i := range s {
		i := i // want "copying variable is unneeded"
		go f(i)
	}
	for _, v := range s {
		v := v // want "copying variable is unneeded"
		go f(v)
	}
	for k, v := range m {
		k := k // want "copying variable is unneeded"
		v := v // want "copying variable is unneeded"
		go f(k)
		go f(v)
	}
	for k, v := range m {
		v := v // want "copying variable is unneeded"
		k := k // want "copying variable is unneeded"
		go f(k)
		go f(v)
	}
	for k, v := range m {
		k, v := k, v // want "copying variable is unneeded"
		go f(k)
		go f(v)
	}
	for k, v := range m {
		v, k := v, k // want "copying variable is unneeded"
		go f(k)
		go f(v)
	}
	for i := range s {
		/* hi */ i := i // want "copying variable is unneeded"
		go f(i)
	}
	for v := range m {
		if v := v; true { // want "copying variable is unneeded"
			print(v)
		}
	}

	// nope
	var i, k, v int

	for i = range s { // nope, scope change
		i := i
		go f(i)
	}
	for _, v = range s { // nope, scope change
		v := v
		go f(v)
	}
	for k = range m { // nope, scope change
		k := k
		go f(k)
	}
	for k, v = range m { // nope, scope change
		k := k
		v := v
		go f(k)
		go f(v)
	}
	for _, v = range m { // nope, scope change
		v := v
		go f(v)
	}
	for _, v = range m { // nope, not x := x
		v := i
		go f(v)
	}
	for k, v := range m { // nope, LHS and RHS differ
		v, k := k, v
		go f(k)
		go f(v)
	}
	for k, v := range m { // nope, not a simple redecl
		k, v, x := k, v, 1
		go f(k)
		go f(v)
		go f(x)
	}
	for i := range s { // nope, not a simple redecl
		i := (i)
		go f(i)
	}
	for i := range s { // nope, not a simple redecl
		i := i + 1
		go f(i)
	}
	for v := range m {
		if v := v; true { // nope, would merge distinct outer and inner variables v
			print(v)
		}
		print(v)
	}
}

func f(n int) {}


================================================
FILE: go/analysis/passes/modernize/testdata/src/forvar/forvar.go.golden
================================================
package forvar

func _(m map[int]int, s []int) {
	// changed
	for i := range s {
		go f(i)
	}
	for _, v := range s {
		go f(v)
	}
	for k, v := range m {
		go f(k)
		go f(v)
	}
	for k, v := range m {
		go f(k)
		go f(v)
	}
	for k, v := range m {
		go f(k)
		go f(v)
	}
	for k, v := range m {
		go f(k)
		go f(v)
	}
	for i := range s {
		go f(i)
	}
	for v := range m {
		if true { // want "copying variable is unneeded"
			print(v)
		}
	}

	// nope
	var i, k, v int

	for i = range s { // nope, scope change
		i := i
		go f(i)
	}
	for _, v = range s { // nope, scope change
		v := v
		go f(v)
	}
	for k = range m { // nope, scope change
		k := k
		go f(k)
	}
	for k, v = range m { // nope, scope change
		k := k
		v := v
		go f(k)
		go f(v)
	}
	for _, v = range m { // nope, scope change
		v := v
		go f(v)
	}
	for _, v = range m { // nope, not x := x
		v := i
		go f(v)
	}
	for k, v := range m { // nope, LHS and RHS differ
		v, k := k, v
		go f(k)
		go f(v)
	}
	for k, v := range m { // nope, not a simple redecl
		k, v, x := k, v, 1
		go f(k)
		go f(v)
		go f(x)
	}
	for i := range s { // nope, not a simple redecl
		i := (i)
		go f(i)
	}
	for i := range s { // nope, not a simple redecl
		i := i + 1
		go f(i)
	}
	for v := range m {
		if v := v; true { // nope, would merge distinct outer and inner variables v
			print(v)
		}
		print(v)
	}
}

func f(n int) {}


================================================
FILE: go/analysis/passes/modernize/testdata/src/mapsloop/mapsloop.go
================================================
//go:build go1.23

package mapsloop

import (
	"iter"
	"maps"
)

var _ = maps.Clone[M] // force "maps" import so that each diagnostic doesn't add one

type M map[int]string

// -- src is map --

func useCopy(dst, src map[int]string) {
	// Replace loop by maps.Copy.
	for key, value := range src {
		// A
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
}

func useCopyRetrieveMap(x map[int]int) {
	getMap := func(int) map[int]int { return nil }
	for i, v := range x {
		// TODO(yuchen): don't assume that getMap returns the same map each time and has no effects.
		//
		// So, to avoid changing the cardinality of side effects,
		// the limit expression must not involve function calls (e.g. seq.Len()) or channel receives.
		getMap(0)[i] = v // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
}

func useCopyGeneric[K comparable, V any, M ~map[K]V](dst, src M) {
	// Replace loop by maps.Copy.
	for key, value := range src {
		// A
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
}

func useCopyNotClone(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace make(...) by maps.Copy.
	dst := make(map[int]string, len(src))
	// A
	for key, value := range src {
		// B
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
		// C
	}

	// A
	dst = map[int]string{}
	// B
	for key, value := range src {
		// C
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useCopyParen(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace (make)(...) by maps.Clone.
	dst := (make)(map[int]string, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}

	dst = (map[int]string{})
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useCopy_typesDiffer(src M) {
	// Replace loop but not make(...) as maps.Copy(src) would return wrong type M.
	dst := make(map[int]string, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useCopy_typesDiffer2(src map[int]string) {
	// Replace loop but not make(...) as maps.Copy(src) would return wrong type map[int]string.
	dst := make(M, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useClone_typesDiffer3(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) as maps.Clone(src) returns map[int]string
	// which is assignable to M.
	var dst M
	dst = make(M, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useClone_typesDiffer4(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) as maps.Clone(src) returns map[int]string
	// which is assignable to M.
	var dst M
	dst = make(M, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

func useClone_generic[Map ~map[K]V, K comparable, V any](src Map) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) by maps.Clone
	dst := make(Map, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}

// -- src is iter.Seq2 --

func useInsert_assignableToSeq2(dst map[int]string, src func(yield func(int, string) bool)) {
	// Replace loop by maps.Insert because src is assignable to iter.Seq2.
	for k, v := range src {
		dst[k] = v // want "Replace m\\[k\\]=v loop with maps.Insert"
	}
}

func useCollect(src iter.Seq2[int, string]) {
	// Replace loop and make(...) by maps.Collect.
	var dst map[int]string
	dst = make(map[int]string) // A
	// B
	for key, value := range src {
		// C
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Collect"
	}
}

func useInsert_typesDifferAssign(src iter.Seq2[int, string]) {
	// Replace loop and make(...): maps.Collect returns an unnamed map type
	// that is assignable to M.
	var dst M
	dst = make(M)
	// A
	for key, value := range src {
		// B
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Collect"
	}
}

func useInsert_typesDifferDeclare(src iter.Seq2[int, string]) {
	// Replace loop but not make(...) as maps.Collect would return an
	// unnamed map type that would change the type of dst.
	dst := make(M)
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Insert"
	}
}

// -- non-matches --

type isomerOfSeq2 func(yield func(int, string) bool)

func nopeInsertRequiresAssignableToSeq2(dst map[int]string, src isomerOfSeq2) {
	for k, v := range src { // nope: src is not assignable to maps.Insert's iter.Seq2 parameter
		dst[k] = v
	}
}

func nopeSingleVarRange(dst map[int]bool, src map[int]string) {
	for key := range src { // nope: must be "for k, v"
		dst[key] = true
	}
}

func nopeBodyNotASingleton(src map[int]string) {
	var dst map[int]string
	for key, value := range src {
		dst[key] = value
		println() // nope: other things in the loop body
	}
}

// Regression test for https://github.com/golang/go/issues/70815#issuecomment-2581999787.
func nopeAssignmentHasIncrementOperator(src map[int]int) {
	dst := make(map[int]int)
	for k, v := range src {
		dst[k] += v
	}
}

func nopeNotAMap(src map[int]string) {
	var dst []string
	for k, v := range src {
		dst[k] = v
	}
}

func nopeNotAMapGeneric[E any, M ~map[int]E, S ~[]E](src M) {
	var dst S
	for k, v := range src {
		dst[k] = v
	}
}

func nopeHasImplicitValueWidening(src map[string]int) {
	dst := make(map[string]any)
	for k, v := range src {
		dst[k] = v
	}
}

func nopeHasImplicitKeyWidening(src map[string]string) {
	dst := make(map[any]string)
	for k, v := range src {
		dst[k] = v
	}
}

// The expression for the map (y[v]) must not itself refer to loop variables.
// See https://go.dev/issue/77008.
func nopeMapExprUsesLoopVars(x map[int]int, y []map[int]int) {
	for i, v := range x {
		y[v][i] = v
	}
}

func nopeExtraKeyValueUsage(x map[int]int, y []map[int]int) {
	for i, v := range x {
		y[i][i] = v
	}

	getMap := func(int) map[int]int { return nil }
	for i, v := range x {
		getMap(i)[i] = v
	}

	for i, v := range x {
		getMap(v)[i] = v
	}
}

func nope2LhsAssigment(x map[int]int, y map[int]int) {
	for i, v := range x {
		y[i], _ = v, 0
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/mapsloop/mapsloop.go.golden
================================================
//go:build go1.23

package mapsloop

import (
	"iter"
	"maps"
)

var _ = maps.Clone[M] // force "maps" import so that each diagnostic doesn't add one

type M map[int]string

// -- src is map --

func useCopy(dst, src map[int]string) {
	// Replace loop by maps.Copy.
	// A
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
}

func useCopyRetrieveMap(x map[int]int) {
	getMap := func(int) map[int]int { return nil }
	// TODO(yuchen): don't assume that getMap returns the same map each time and has no effects.
	//
	// So, to avoid changing the cardinality of side effects,
	// the limit expression must not involve function calls (e.g. seq.Len()) or channel receives.
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(getMap(0), x)
}

func useCopyGeneric[K comparable, V any, M ~map[K]V](dst, src M) {
	// Replace loop by maps.Copy.
	// A
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
}

func useCopyNotClone(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace make(...) by maps.Copy.
	dst := make(map[int]string, len(src))
	// A
	// B
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	// C
	maps.Copy(dst, src)

	// A
	dst = map[int]string{}
	// B
	// C
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useCopyParen(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace (make)(...) by maps.Clone.
	dst := (make)(map[int]string, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)

	dst = (map[int]string{})
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useCopy_typesDiffer(src M) {
	// Replace loop but not make(...) as maps.Copy(src) would return wrong type M.
	dst := make(map[int]string, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useCopy_typesDiffer2(src map[int]string) {
	// Replace loop but not make(...) as maps.Copy(src) would return wrong type map[int]string.
	dst := make(M, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useClone_typesDiffer3(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) as maps.Clone(src) returns map[int]string
	// which is assignable to M.
	var dst M
	dst = make(M, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useClone_typesDiffer4(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) as maps.Clone(src) returns map[int]string
	// which is assignable to M.
	var dst M
	dst = make(M, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

func useClone_generic[Map ~map[K]V, K comparable, V any](src Map) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace loop and make(...) by maps.Clone
	dst := make(Map, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	maps.Copy(dst, src)
	println(dst)
}

// -- src is iter.Seq2 --

func useInsert_assignableToSeq2(dst map[int]string, src func(yield func(int, string) bool)) {
	// Replace loop by maps.Insert because src is assignable to iter.Seq2.
	// want "Replace m\\[k\\]=v loop with maps.Insert"
	maps.Insert(dst, src)
}

func useCollect(src iter.Seq2[int, string]) {
	// Replace loop and make(...) by maps.Collect.
	var dst map[int]string
	// A
	// B
	// C
	// want "Replace m\\[k\\]=v loop with maps.Collect"
	dst = maps.Collect(src)
}

func useInsert_typesDifferAssign(src iter.Seq2[int, string]) {
	// Replace loop and make(...): maps.Collect returns an unnamed map type
	// that is assignable to M.
	var dst M
	// A
	// B
	// want "Replace m\\[k\\]=v loop with maps.Collect"
	dst = maps.Collect(src)
}

func useInsert_typesDifferDeclare(src iter.Seq2[int, string]) {
	// Replace loop but not make(...) as maps.Collect would return an
	// unnamed map type that would change the type of dst.
	dst := make(M)
	// want "Replace m\\[k\\]=v loop with maps.Insert"
	maps.Insert(dst, src)
}

// -- non-matches --

type isomerOfSeq2 func(yield func(int, string) bool)

func nopeInsertRequiresAssignableToSeq2(dst map[int]string, src isomerOfSeq2) {
	for k, v := range src { // nope: src is not assignable to maps.Insert's iter.Seq2 parameter
		dst[k] = v
	}
}

func nopeSingleVarRange(dst map[int]bool, src map[int]string) {
	for key := range src { // nope: must be "for k, v"
		dst[key] = true
	}
}

func nopeBodyNotASingleton(src map[int]string) {
	var dst map[int]string
	for key, value := range src {
		dst[key] = value
		println() // nope: other things in the loop body
	}
}

// Regression test for https://github.com/golang/go/issues/70815#issuecomment-2581999787.
func nopeAssignmentHasIncrementOperator(src map[int]int) {
	dst := make(map[int]int)
	for k, v := range src {
		dst[k] += v
	}
}

func nopeNotAMap(src map[int]string) {
	var dst []string
	for k, v := range src {
		dst[k] = v
	}
}

func nopeNotAMapGeneric[E any, M ~map[int]E, S ~[]E](src M) {
	var dst S
	for k, v := range src {
		dst[k] = v
	}
}

func nopeHasImplicitValueWidening(src map[string]int) {
	dst := make(map[string]any)
	for k, v := range src {
		dst[k] = v
	}
}

func nopeHasImplicitKeyWidening(src map[string]string) {
	dst := make(map[any]string)
	for k, v := range src {
		dst[k] = v
	}
}

// The expression for the map (y[v]) must not itself refer to loop variables.
// See https://go.dev/issue/77008.
func nopeMapExprUsesLoopVars(x map[int]int, y []map[int]int) {
	for i, v := range x {
		y[v][i] = v
	}
}

func nopeExtraKeyValueUsage(x map[int]int, y []map[int]int) {
	for i, v := range x {
		y[i][i] = v
	}

	getMap := func(int) map[int]int { return nil }
	for i, v := range x {
		getMap(i)[i] = v
	}

	for i, v := range x {
		getMap(v)[i] = v
	}
}

func nope2LhsAssigment(x map[int]int, y map[int]int) {
	for i, v := range x {
		y[i], _ = v, 0
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/mapsloop/mapsloop_dot.go
================================================
//go:build go1.23

package mapsloop

import . "maps"

var _ = Clone[M] // force "maps" import so that each diagnostic doesn't add one

func useCopyDot(dst, src map[int]string) {
	// Replace loop by maps.Copy.
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
}

func useCloneDot(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace make(...) by maps.Copy.
	dst := make(map[int]string, len(src))
	for key, value := range src {
		dst[key] = value // want "Replace m\\[k\\]=v loop with maps.Copy"
	}
	println(dst)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/mapsloop/mapsloop_dot.go.golden
================================================
//go:build go1.23

package mapsloop

import . "maps"

var _ = Clone[M] // force "maps" import so that each diagnostic doesn't add one

func useCopyDot(dst, src map[int]string) {
	// Replace loop by maps.Copy.
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	Copy(dst, src)
}

func useCloneDot(src map[int]string) {
	// Clone is tempting but wrong when src may be nil; see #71844.

	// Replace make(...) by maps.Copy.
	dst := make(map[int]string, len(src))
	// want "Replace m\\[k\\]=v loop with maps.Copy"
	Copy(dst, src)
	println(dst)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/go120/minmax.go
================================================
package go120


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/go120/minmax_go120.go
================================================
//go:build !go1.21

package go120

func min(a, b int) int { // can't be removed because we don't have at least go1.21
	if a <= b {
		return a
	} else {
		return b
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/go120/minmax_go120.go.golden
================================================
//go:build !go1.21

package go120

func min(a, b int) int { // can't be removed because we don't have at least go1.21
	if a <= b {
		return a
	} else {
		return b
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/minmax.go
================================================
package minmax

func ifmin(a, b int) {
	x := a // A
	// B
	if a < b { // want "if statement can be modernized using max"
		// C
		x = b // D
		// E
	}
	print(x)
}

func ifmax(a, b int) {
	x := a
	if a > b { // want "if statement can be modernized using min"
		x = b
	}
	print(x)
}

func ifminvariant(a, b int) {
	x := a
	if x > b { // want "if statement can be modernized using min"
		x = b
	}
	print(x)
}

func ifmaxvariant(a, b int) {
	x := b
	if a < x { // want "if statement can be modernized using min"
		x = a
	}
	print(x)
}

func ifelsemin(a, b int) {
	var x int // A
	// B
	if a <= b { // want "if/else statement can be modernized using min"
		// C
		x = a // D
		// E
	} else {
		// F
		x = b // G
		// H
	}
	print(x)
}

func ifelsemax(a, b int) {
	// A
	var x int // B
	// C
	if a >= b { // want "if/else statement can be modernized using max"
		// D
		x = a // E
		// F
	} else {
		// G
		x = b
	}
	print(x)
}

func shadowed() int {
	hour, min := 3600, 60

	var time int
	if hour < min { // silent: the built-in min function is shadowed here
		time = hour
	} else {
		time = min
	}
	return time
}

func nopeIfStmtHasInitStmt() {
	x := 1
	if y := 2; y < x { // silent: IfStmt has an Init stmt
		x = y
	}
	print(x)
}

// Regression test for a bug: fix was "y := max(x, y)".
func oops() {
	x := 1
	y := 2
	if x > y { // want "if statement can be modernized using max"
		y = x
	}
	print(y)
}

// Regression test for a bug: += is not a simple assignment.
func nopeAssignHasIncrementOperator() {
	x := 1
	y := 0
	y += 2
	if x > y {
		y = x
	}
	print(y)
}

// Regression test for https://github.com/golang/go/issues/71721.
func nopeNotAMinimum(x, y int) int {
	// A value of -1 or 0 will use a default value (30).
	if x <= 0 {
		y = 30
	} else {
		y = x
	}
	return y
}

// Regression test for https://github.com/golang/go/issues/71847#issuecomment-2673491596
func nopeHasElseBlock(x int) int {
	y := x
	// Before, this was erroneously reduced to y = max(x, 0)
	if y < 0 {
		y = 0
	} else {
		y += 2
	}
	return y
}

func fix72727(a, b int) {
	o := a - 42
	// some important comment. DO NOT REMOVE.
	if o < b { // want "if statement can be modernized using max"
		o = b
	}
}

type myfloat float64

// The built-in min/max differ in their treatment of NaN,
// so reject floating-point numbers (#72829).
func nopeFloat(a, b myfloat) (res myfloat) {
	if a < b {
		res = a
	} else {
		res = b
	}
	return
}

// Regression test for golang/go#72928.
func underscoreAssign(a, b int) {
	if a > b {
		_ = a
	}
}

// Regression test for https://github.com/golang/go/issues/73576.
func nopeIfElseIf(a int) int {
	x := 0
	if a < 0 {
		x = 0
	} else if a > 100 {
		x = 100
	} else {
		x = a
	}
	return x
}

// Regression test for https://go.dev/issue/77671
func selectComm(ch chan int) int {
	select {
	case n := <-ch:
		if n > 100 {
			n = 100
		}
		return n
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/minmax.go.golden
================================================
package minmax

func ifmin(a, b int) {
	x := max(
		// A
		// B
		a,
		// want "if statement can be modernized using max"
		// C
		// D
		// E
		b)
	print(x)
}

func ifmax(a, b int) {
	x := min(a,
		// want "if statement can be modernized using min"
		b)
	print(x)
}

func ifminvariant(a, b int) {
	x := min(a,
		// want "if statement can be modernized using min"
		b)
	print(x)
}

func ifmaxvariant(a, b int) {
	x := min(a,
		// want "if statement can be modernized using min"
		b)
	print(x)
}

func ifelsemin(a, b int) {
	var x int // A
	// B
	x = min(
		// want "if/else statement can be modernized using min"
		// C
		// D
		// E
		a,
		// F
		// G
		// H
		b)
	print(x)
}

func ifelsemax(a, b int) {
	// A
	var x int // B
	// C
	x = max(
		// want "if/else statement can be modernized using max"
		// D
		// E
		// F
		a,
		// G
		b)
	print(x)
}

func shadowed() int {
	hour, min := 3600, 60

	var time int
	if hour < min { // silent: the built-in min function is shadowed here
		time = hour
	} else {
		time = min
	}
	return time
}

func nopeIfStmtHasInitStmt() {
	x := 1
	if y := 2; y < x { // silent: IfStmt has an Init stmt
		x = y
	}
	print(x)
}

// Regression test for a bug: fix was "y := max(x, y)".
func oops() {
	x := 1
	y := max(x,
		// want "if statement can be modernized using max"
		2)
	print(y)
}

// Regression test for a bug: += is not a simple assignment.
func nopeAssignHasIncrementOperator() {
	x := 1
	y := 0
	y += 2
	if x > y {
		y = x
	}
	print(y)
}

// Regression test for https://github.com/golang/go/issues/71721.
func nopeNotAMinimum(x, y int) int {
	// A value of -1 or 0 will use a default value (30).
	if x <= 0 {
		y = 30
	} else {
		y = x
	}
	return y
}

// Regression test for https://github.com/golang/go/issues/71847#issuecomment-2673491596
func nopeHasElseBlock(x int) int {
	y := x
	// Before, this was erroneously reduced to y = max(x, 0)
	if y < 0 {
		y = 0
	} else {
		y += 2
	}
	return y
}

func fix72727(a, b int) {
	o := max(
		// some important comment. DO NOT REMOVE.
		a-42,
		// want "if statement can be modernized using max"
		b)
}

type myfloat float64

// The built-in min/max differ in their treatment of NaN,
// so reject floating-point numbers (#72829).
func nopeFloat(a, b myfloat) (res myfloat) {
	if a < b {
		res = a
	} else {
		res = b
	}
	return
}

// Regression test for golang/go#72928.
func underscoreAssign(a, b int) {
	if a > b {
		_ = a
	}
}

// Regression test for https://github.com/golang/go/issues/73576.
func nopeIfElseIf(a int) int {
	x := 0
	if a < 0 {
		x = 0
	} else if a > 100 {
		x = 100
	} else {
		x = a
	}
	return x
}

// Regression test for https://go.dev/issue/77671
func selectComm(ch chan int) int {
	select {
	case n := <-ch:
		if n > 100 {
			n = 100
		}
		return n
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/nonstrict/nonstrict.go
================================================
package nonstrict

// min with <= operator - should be detected and removed
func min(a, b int) int { // want "user-defined min function is equivalent to built-in min and can be removed"
	if a <= b {
		return a
	} else {
		return b
	}
}

// max with >= operator - should be detected and removed
func max(a, b int) int { // want "user-defined max function is equivalent to built-in max and can be removed"
	if a >= b {
		return a
	}
	return b
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/nonstrict/nonstrict.go.golden
================================================
package nonstrict

================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/userdefined/userdefined.go
================================================
package userdefined

// User-defined min with float parameters - should NOT be removed due to NaN handling
func minFloat(a, b float64) float64 {
	if a < b {
		return a
	} else {
		return b
	}
}

// User-defined max with float parameters - should NOT be removed due to NaN handling
func maxFloat(a, b float64) float64 {
	if a > b {
		return a
	} else {
		return b
	}
}

// User-defined function with different name - should NOT be removed
func minimum(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

// User-defined min with different logic - should NOT be removed
func minDifferent(a, b int) int {
	return a + b // Completely different logic
}

// Method on a type - should NOT be removed
type MyType struct{}

func (m MyType) min(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

// Function with wrong signature - should NOT be removed
func minWrongSig(a int) int {
	return a
}

// Function with complex body that doesn't match pattern - should NOT be removed
func minComplex(a, b int) int {
	println("choosing min")
	if a < b {
		return a
	} else {
		return b
	}
}

// min returns the smaller of two values.
func min(a, b int) int { // want "user-defined min function is equivalent to built-in min and can be removed"
	if a < b {
		return a
	} else {
		return b
	}
}

// max returns the larger of two values.
func max(a, b int) int { // want "user-defined max function is equivalent to built-in max and can be removed"
	if a > b {
		return a
	}
	return b
}




================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/userdefined/userdefined.go.golden
================================================
package userdefined

// User-defined min with float parameters - should NOT be removed due to NaN handling
func minFloat(a, b float64) float64 {
	if a < b {
		return a
	} else {
		return b
	}
}

// User-defined max with float parameters - should NOT be removed due to NaN handling
func maxFloat(a, b float64) float64 {
	if a > b {
		return a
	} else {
		return b
	}
}

// User-defined function with different name - should NOT be removed
func minimum(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

// User-defined min with different logic - should NOT be removed
func minDifferent(a, b int) int {
	return a + b // Completely different logic
}

// Method on a type - should NOT be removed
type MyType struct{}

func (m MyType) min(a, b int) int {
	if a < b {
		return a
	} else {
		return b
	}
}

// Function with wrong signature - should NOT be removed
func minWrongSig(a int) int {
	return a
}

// Function with complex body that doesn't match pattern - should NOT be removed
func minComplex(a, b int) int {
	println("choosing min")
	if a < b {
		return a
	} else {
		return b
	}
}




================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/wrongoperators/wrongoperators.go
================================================
package wrongoperators

// min function with max logic - should NOT be detected (wrong logic)
func min(a, b int) int {
	if a >= b { // This is max logic, not min logic
		return a
	} else {
		return b
	}
}

// max function with min logic - should NOT be detected (wrong logic)
func max(a, b int) int {
	if a <= b { // This is min logic, not max logic
		return a
	} else {
		return b
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/wrongoperators/wrongoperators.go.golden
================================================
package operators

// min function with max logic - should NOT be detected (wrong logic)
func min(a, b int) int {
	if a >= b {  // This is max logic, not min logic
		return a
	} else {
		return b
	}
}

// max function with min logic - should NOT be detected (wrong logic)
func max(a, b int) int {
	if a <= b {  // This is min logic, not max logic
		return a
	} else {
		return b
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/wrongreturn/wrongreturn.go
================================================
package wrongreturn

// This should NOT be detected as min - it returns the wrong values
func min(x, y int) int {
	if x <= y {
		return y
	} else {
		return x
	}
}

// This should NOT be detected as max - it returns the wrong values
func max(x, y int) int {
	if x > y {
		return y
	} else {
		return x
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/minmax/wrongreturn/wrongreturn.go.golden
================================================
package wrongreturn

// This should NOT be detected as min - it returns the wrong values
func min(x, y int) int {
	if x <= y {
		return y
	} else {
		return x
	}
}

// This should NOT be detected as max - it returns the wrong values  
func max(x, y int) int {
	if x > y {
		return y
	} else {
		return x
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/newexpr/newexpr.go
================================================
//go:build go1.26

package newexpr

// intVar returns a new var whose value is i.
func intVar(i int) *int { return &i } // want `intVar can be an inlinable wrapper around new\(expr\)` intVar:"newlike"

func int64Var(i int64) *int64 { return &i } // want `int64Var can be an inlinable wrapper around new\(expr\)` int64Var:"newlike"

func stringVar(s string) *string { return &s } // want `stringVar can be an inlinable wrapper around new\(expr\)` stringVar:"newlike"

func varOf[T any](x T) *T { return &x } // want `varOf can be an inlinable wrapper around new\(expr\)` varOf:"newlike"

//go:fix inline
func alreadyAnnotated[T any](x T) *T { return &x } // want `alreadyAnnotated can be an inlinable wrapper around new\(expr\)` alreadyAnnotated:"newlike"

var (
	s struct {
		int
		string
	}
	_ = intVar(123)       // want `call of intVar\(x\) can be simplified to new\(x\)`
	_ = int64Var(123)     // nope: implicit conversion from untyped int to int64
	_ = stringVar("abc")  // want `call of stringVar\(x\) can be simplified to new\(x\)`
	_ = varOf(s)          // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = varOf(123)        // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = varOf(int64(123)) // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = varOf[int](123)   // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = varOf[int64](123) // nope: implicit conversion from untyped int to int64
	_ = varOf( // want `call of varOf\(x\) can be simplified to new\(x\)`
		varOf(123)) // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = alreadyAnnotated[int](123) // want `call of alreadyAnnotated\(x\) can be simplified to new\(x\)`
)


================================================
FILE: go/analysis/passes/modernize/testdata/src/newexpr/newexpr.go.golden
================================================
//go:build go1.26

package newexpr

// intVar returns a new var whose value is i.
//
//go:fix inline
func intVar(i int) *int { return new(i) } // want `intVar can be an inlinable wrapper around new\(expr\)` intVar:"newlike"

//go:fix inline
func int64Var(i int64) *int64 { return new(i) } // want `int64Var can be an inlinable wrapper around new\(expr\)` int64Var:"newlike"

//go:fix inline
func stringVar(s string) *string { return new(s) } // want `stringVar can be an inlinable wrapper around new\(expr\)` stringVar:"newlike"

//go:fix inline
func varOf[T any](x T) *T { return new(x) } // want `varOf can be an inlinable wrapper around new\(expr\)` varOf:"newlike"

//go:fix inline
func alreadyAnnotated[T any](x T) *T { return new(x) } // want `alreadyAnnotated can be an inlinable wrapper around new\(expr\)` alreadyAnnotated:"newlike"

var (
	s struct {
		int
		string
	}
	_ = new(123)          // want `call of intVar\(x\) can be simplified to new\(x\)`
	_ = int64Var(123)     // nope: implicit conversion from untyped int to int64
	_ = new("abc")        // want `call of stringVar\(x\) can be simplified to new\(x\)`
	_ = new(s)            // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = new(123)          // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = new(int64(123))   // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = new(123)          // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = varOf[int64](123) // nope: implicit conversion from untyped int to int64
	_ = new(              // want `call of varOf\(x\) can be simplified to new\(x\)`
		new(123)) // want `call of varOf\(x\) can be simplified to new\(x\)`
	_ = new(123) // want `call of alreadyAnnotated\(x\) can be simplified to new\(x\)`
)

================================================
FILE: go/analysis/passes/modernize/testdata/src/newexpr/newexpr_go125.go
================================================
package newexpr


================================================
FILE: go/analysis/passes/modernize/testdata/src/omitzero/kube/kube.go
================================================
package kube

type Foo struct {
	EmptyStruct struct{} `json:",omitempty"` // nope: the comment below mentions the k-word
}

// +kubebuilder:validation:Optional
type Other struct {
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/omitzero/omitzero.go
================================================
package omitzero

type Foo struct {
	EmptyStruct struct{} `json:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}

type Bar struct {
	NonEmptyStruct struct{ a int } `json:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}

type C struct {
	D string `json:",omitempty"`
}

type R struct {
	M string `json:",omitempty"`
}

type A struct {
	C C `json:"test,omitempty"` // want "Omitempty has no effect on nested struct fields"
	R R `json:"test"`
}

type X struct {
	NonEmptyStruct struct{ a int } `json:",omitempty" yaml:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}

type Y struct {
	NonEmptyStruct struct{ a int } `yaml:",omitempty" json:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/omitzero/omitzero.go.golden
================================================
-- Replace omitempty with omitzero (behavior change) --
package omitzero

type Foo struct {
	EmptyStruct struct{} `json:",omitzero"` // want "Omitempty has no effect on nested struct fields"
}

type Bar struct {
	NonEmptyStruct struct{ a int } `json:",omitzero"` // want "Omitempty has no effect on nested struct fields"
}

type C struct {
	D string `json:",omitempty"`
}

type R struct {
	M string `json:",omitempty"`
}

type A struct {
	C C `json:"test,omitzero"` // want "Omitempty has no effect on nested struct fields"
	R R `json:"test"`
}

type X struct {
	NonEmptyStruct struct{ a int } `json:",omitzero" yaml:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}

type Y struct {
	NonEmptyStruct struct{ a int } `yaml:",omitempty" json:",omitzero"` // want "Omitempty has no effect on nested struct fields"
}

-- Remove redundant omitempty tag --
package omitzero

type Foo struct {
	EmptyStruct struct{} // want "Omitempty has no effect on nested struct fields"
}

type Bar struct {
	NonEmptyStruct struct{ a int } // want "Omitempty has no effect on nested struct fields"
}

type C struct {
	D string `json:",omitempty"`
}

type R struct {
	M string `json:",omitempty"`
}

type A struct {
	C C `json:"test"` // want "Omitempty has no effect on nested struct fields"
	R R `json:"test"`
}

type X struct {
	NonEmptyStruct struct{ a int } `yaml:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}

type Y struct {
	NonEmptyStruct struct{ a int } `yaml:",omitempty"` // want "Omitempty has no effect on nested struct fields"
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/plusbuild/plusbuild.go
================================================
// want +3 `.build line is no longer needed`

//go:build linux && amd64
// +build linux,amd64

package plusbuild


================================================
FILE: go/analysis/passes/modernize/testdata/src/plusbuild/plusbuild.go.golden
================================================
// want +3 `.build line is no longer needed`

//go:build linux && amd64

package plusbuild



================================================
FILE: go/analysis/passes/modernize/testdata/src/plusbuild/plusbuild2.go
================================================
// This file ensures that the package is non-empty
// in every build configuration.

package plusbuild


================================================
FILE: go/analysis/passes/modernize/testdata/src/rangeint/a/a.go
================================================
package a

type ID int


================================================
FILE: go/analysis/passes/modernize/testdata/src/rangeint/rangeint.go
================================================
package rangeint

import (
	"os"
	os1 "os"
	"rangeint/a"
)

func _(i int, s struct{ i int }, slice []int) {
	for i := 0; i < 10; i++ { // want "for loop can be modernized using range over int"
		println(i)
	}
	for j := int(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int8(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int16(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int32(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int64(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := uint8(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := uint16(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := uint32(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := uint64(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int8(0.); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := int8(.0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := os.FileMode(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}

	{
		var i int
		for i = 0; i < 10; i++ { // want "for loop can be modernized using range over int"
		}
		// NB: no uses of i after loop.
	}
	for i := 0; i < 10; i++ { // want "for loop can be modernized using range over int"
		// i unused within loop
	}
	for i := 0; i < len(slice); i++ { // want "for loop can be modernized using range over int"
		println(slice[i])
	}
	for i := 0; i < len(""); i++ { // want "for loop can be modernized using range over int"
		// NB: not simplified to range ""
	}

	// nope
	for j := .0; j < 10; j++ { // nope: j is a float type
		println(j)
	}
	for j := float64(0); j < 10; j++ { // nope: j is a float type
		println(j)
	}
	for i := 0; i < 10; { // nope: missing increment
	}
	for i := 0; i < 10; i-- { // nope: negative increment
	}
	for i := 0; ; i++ { // nope: missing comparison
	}
	for i := 0; i <= 10; i++ { // nope: wrong comparison
	}
	for ; i < 10; i++ { // nope: missing init
	}
	for s.i = 0; s.i < 10; s.i++ { // nope: not an ident
	}
	for i := 0; i < 10; i++ { // nope: takes address of i
		println(&i)
	}
	for i := 0; i < 10; i++ { // nope: increments i
		i++
	}
	for i := 0; i < 10; i++ { // nope: assigns i
		i = 8
	}

	for i := 0; i < 10; i += 1 { // want "for loop can be modernized using range over int"
		println(i)
	}
	for i := 0; i < 10; s.i += 1 { // nope: modifies another variable
		println(i)
	}
	for i := 0; i < 10; i -= 1 { // nope: decrements i
		println(i)
	}
	for i := 0; i < 10; i += 2 { // nope: range only increments by 1
		println(i)
	}

	// The limit expression must be loop invariant;
	// see https://github.com/golang/go/issues/72917
	for i := 0; i < f(); i++ { // nope
	}
	{
		var s struct{ limit int }
		for i := 0; i < s.limit; i++ { // nope: limit is not a const or local var
		}
	}
	{
		const k = 10
		for i := 0; i < k; i++ { // want "for loop can be modernized using range over int"
		}
	}
	{
		var limit = 10
		for i := 0; i < limit; i++ { // want "for loop can be modernized using range over int"
		}
	}
	{
		var limit = 10
		for i := 0; i < limit; i++ { // nope: limit is address-taken
		}
		print(&limit)
	}
	{
		limit := 10
		limit++
		for i := 0; i < limit; i++ { // nope: limit is assigned other than by its declaration
		}
	}
	for i := 0; i < Global; i++ { // nope: limit is an exported global var; may be updated elsewhere
	}
	for i := 0; i < len(table); i++ { // want "for loop can be modernized using range over int"
	}
	{
		s := []string{}
		for i := 0; i < len(s); i++ { // nope: limit is not loop-invariant
			s = s[1:]
		}
	}
	for i := 0; i < len(slice); i++ { // nope: i is incremented within loop
		i += 1
	}
	for Global = 0; Global < 10; Global++ { // nope: loop index is a global variable.
	}
}

var Global int

var table = []string{"hello", "world"}

func f() int { return 0 }

// Repro for part of #71847: ("for range n is invalid if the loop body contains i++"):
func _(s string) {
	var i int                    // (this is necessary)
	for i = 0; i < len(s); i++ { // nope: loop body increments i
		if true {
			i++ // nope
		}
	}
}

// Repro for #71952: for and range loops have different final values
// on i (n and n-1, respectively) so we can't offer the fix if i is
// used after the loop.
func nopePostconditionDiffers() {
	i := 0
	for i = 0; i < 5; i++ {
		println(i)
	}
	println(i) // must print 5, not 4
}

// Non-integer untyped constants need to be explicitly converted to int.
func issue71847d() {
	const limit = 1e3            // float
	for i := 0; i < limit; i++ { // want "for loop can be modernized using range over int"
	}
	for i := int(0); i < limit; i++ { // want "for loop can be modernized using range over int"
	}
	for i := uint(0); i < limit; i++ { // want "for loop can be modernized using range over int"
	}

	const limit2 = 1 + 0i         // complex
	for i := 0; i < limit2; i++ { // want "for loop can be modernized using range over int"
	}
}

func issue72726() {
	var n, kd int
	for i := 0; i < n; i++ { // want "for loop can be modernized using range over int"
		// nope: j will be invisible once it's refactored to 'for j := range min(n-j, kd+1)'
		for j := 0; j < min(n-j, kd+1); j++ { // nope
			_, _ = i, j
		}
	}

	for i := 0; i < i; i++ { // nope
	}

	var i int
	for i = 0; i < i/2; i++ { // nope
	}

	var arr []int
	for i = 0; i < arr[i]; i++ { // nope
	}
}

func todo() {
	for j := os1.FileMode(0); j < 10; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}
}

type T uint
type TAlias = uint

func Fn(a int) T {
	return T(a)
}

func issue73037() {
	var q T
	for a := T(0); a < q; a++ { // want "for loop can be modernized using range over int"
		println(a)
	}
	for a := Fn(0); a < q; a++ {
		println(a)
	}
	var qa TAlias
	for a := TAlias(0); a < qa; a++ { // want "for loop can be modernized using range over int"
		println(a)
	}
	for a := T(0); a < 10; a++ { // want "for loop can be modernized using range over int"
		for b := T(0); b < 10; b++ { // want "for loop can be modernized using range over int"
			println(a, b)
		}
	}
}

func issue75289() {
	// A use of i within a defer may be textually before the loop but runs
	// after, so it should cause the loop to be rejected as a candidate
	// to avoid it observing a different final value of i.
	{
		var i int
		defer func() { println(i) }()
		for i = 0; i < 10; i++ { // nope: i is accessed after the loop (via defer)
		}
	}

	// A use of i within a defer within the loop is also a dealbreaker.
	{
		var i int
		for i = 0; i < 10; i++ { // nope: i is accessed after the loop (via defer)
			defer func() { println(i) }()
		}
	}

	// This (outer) defer is irrelevant.
	defer func() {
		var i int
		for i = 0; i < 10; i++ { // want "for loop can be modernized using range over int"
		}
	}()
}

// See go.dev/issue/76880.
func _() (i int) {
	for i = 0; i < 3; i++ { // nope: i is implicitly accessed after the loop
	}
	return
}

func issue74687() {
	for i := a.ID(0); i < 10; i++ { // want "for loop can be modernized using range over int"
		println(i)
	}

	for i := a.ID(0); i < a.ID(13); i++ { // want "for loop can be modernized using range over int"
		println(i)
	}
}

func issue76470() {
	var i, j int
UsedAfter:
	for i = 0; i < 10; i++ { // nope: i is accessed after the loop
		break UsedAfter
	}
	if i == 9 {
		panic("Modernizer changes behavior")
	}

NotUsedAfter:
	for j = 0; j < 10; j++ { // want "for loop can be modernized using range over int"
		break NotUsedAfter
	}
}

// Don't allow rewriting of an outer loop when its inner loop modifies the outer
// loop variable.
func issue77034() {
	for i := 0; i < 5; i++ {
		for i = range 10 {
		}
	}
}

func issue77034_define_inner() {
	for i := 0; i < 5; i++ { // want "for loop can be modernized using range over int"
		for i := range 10 { // inner "i" doesn't modify outer "i"
			println(i)
		}
	}
}

type C int32

// Don't add an unneeded type cast if the limit's default type is an integer, and
// the init value is assigned outside the loop, because the compiler can infer the type.
func issue77891() {
	const limit_float = 1e6
	var i int
	for i = 0; i < limit_float; i++ { // want "for loop can be modernized using range over int"
		println(i)
	}

	var j int64
	for j = 0; j < 20; j++ { // want "for loop can be modernized using range over int"
		println(j)
	}

	var c C
	for c = 0; c < 10; c++ { // want "for loop can be modernized using range over int"
		println(c)
	}

	var ptr uintptr
	for ptr = 0; ptr < 100; ptr++ { // want "for loop can be modernized using range over int"
		println(ptr)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/rangeint/rangeint.go.golden
================================================
package rangeint

import (
	os1 "os"
	"rangeint/a"
)

func _(i int, s struct{ i int }, slice []int) {
	for i := range 10 { // want "for loop can be modernized using range over int"
		println(i)
	}
	for j := range 10 { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int8(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int16(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int32(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int64(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range uint8(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range uint16(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range uint32(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range uint64(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int8(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range int8(10) { // want "for loop can be modernized using range over int"
		println(j)
	}
	for j := range os1.FileMode(10) { // want "for loop can be modernized using range over int"
		println(j)
	}

	{
		var i int
		for i = range 10 { // want "for loop can be modernized using range over int"
		}
		// NB: no uses of i after loop.
	}
	for range 10 { // want "for loop can be modernized using range over int"
		// i unused within loop
	}
	for i := range slice { // want "for loop can be modernized using range over int"
		println(slice[i])
	}
	for range len("") { // want "for loop can be modernized using range over int"
		// NB: not simplified to range ""
	}

	// nope
	for j := .0; j < 10; j++ { // nope: j is a float type
		println(j)
	}
	for j := float64(0); j < 10; j++ { // nope: j is a float type
		println(j)
	}
	for i := 0; i < 10; { // nope: missing increment
	}
	for i := 0; i < 10; i-- { // nope: negative increment
	}
	for i := 0; ; i++ { // nope: missing comparison
	}
	for i := 0; i <= 10; i++ { // nope: wrong comparison
	}
	for ; i < 10; i++ { // nope: missing init
	}
	for s.i = 0; s.i < 10; s.i++ { // nope: not an ident
	}
	for i := 0; i < 10; i++  { // nope: takes address of i
		println(&i)
	}
	for i := 0; i < 10; i++  { // nope: increments i
		i++
	}
	for i := 0; i < 10; i++  { // nope: assigns i
		i = 8
	}

	for i := range 10 { // want "for loop can be modernized using range over int"
		println(i)
	}
	for i := 0; i < 10; s.i += 1 { // nope: modifies another variable
		println(i)
	}
	for i := 0; i < 10; i -= 1 { // nope: decrements i
		println(i)
	}
	for i := 0; i < 10; i += 2 { // nope: range only increments by 1
		println(i)
	}

	// The limit expression must be loop invariant;
	// see https://github.com/golang/go/issues/72917
	for i := 0; i < f(); i++ { // nope
	}
	{
		var s struct{ limit int }
		for i := 0; i < s.limit; i++ { // nope: limit is not a const or local var
		}
	}
	{
		const k = 10
		for range k { // want "for loop can be modernized using range over int"
		}
	}
	{
		var limit = 10
		for range limit { // want "for loop can be modernized using range over int"
		}
	}
	{
		var limit = 10
		for i := 0; i < limit; i++ { // nope: limit is address-taken
		}
		print(&limit)
	}
	{
		limit := 10
		limit++
		for i := 0; i < limit; i++ { // nope: limit is assigned other than by its declaration
		}
	}
	for i := 0; i < Global; i++ { // nope: limit is an exported global var; may be updated elsewhere
	}
	for range table { // want "for loop can be modernized using range over int"
	}
	{
		s := []string{}
		for i := 0; i < len(s); i++ { // nope: limit is not loop-invariant
			s = s[1:]
		}
	}
	for i := 0; i < len(slice); i++ { // nope: i is incremented within loop
		i += 1
	}
	for Global = 0; Global < 10; Global++ { // nope: loop index is a global variable.
	}
}

var Global int

var table = []string{"hello", "world"}

func f() int { return 0 }

// Repro for part of #71847: ("for range n is invalid if the loop body contains i++"):
func _(s string) {
	var i int                    // (this is necessary)
	for i = 0; i < len(s); i++ { // nope: loop body increments i
		if true {
			i++ // nope
		}
	}
}

// Repro for #71952: for and range loops have different final values
// on i (n and n-1, respectively) so we can't offer the fix if i is
// used after the loop.
func nopePostconditionDiffers() {
	i := 0
	for i = 0; i < 5; i++ {
		println(i)
	}
	println(i) // must print 5, not 4
}

// Non-integer untyped constants need to be explicitly converted to int.
func issue71847d() {
	const limit = 1e3            // float
	for range int(limit) { // want "for loop can be modernized using range over int"
	}
	for range int(limit) { // want "for loop can be modernized using range over int"
	}
	for range uint(limit) { // want "for loop can be modernized using range over int"
	}

	const limit2 = 1 + 0i         // complex
	for range int(limit2) { // want "for loop can be modernized using range over int"
	}
}

func issue72726() {
	var n, kd int
	for i := range n { // want "for loop can be modernized using range over int"
		// nope: j will be invisible once it's refactored to 'for j := range min(n-j, kd+1)'
		for j := 0; j < min(n-j, kd+1); j++ { // nope
			_, _ = i, j
		}
	}

	for i := 0; i < i; i++ { // nope
	}

	var i int
	for i = 0; i < i/2; i++ { // nope
	}

	var arr []int
	for i = 0; i < arr[i]; i++ { // nope
	}
}

func todo() {
	for j := range os1.FileMode(10)  { // want "for loop can be modernized using range over int"
		println(j)
	}
}

type T uint
type TAlias = uint

func Fn(a int) T {
	return T(a)
}

func issue73037() {
	var q T
	for a := range q { // want "for loop can be modernized using range over int"
		println(a)
	}
	for a := Fn(0); a < q; a++ {
		println(a)
	}
	var qa TAlias
	for a := range qa { // want "for loop can be modernized using range over int"
		println(a)
	}
	for a := range T(10) { // want "for loop can be modernized using range over int"
		for b := range T(10) { // want "for loop can be modernized using range over int"
			println(a, b)
		}
	}
}

func issue75289() {
	// A use of i within a defer may be textually before the loop but runs
	// after, so it should cause the loop to be rejected as a candidate
	// to avoid it observing a different final value of i.
	{
		var i int
		defer func() { println(i) }()
		for i = 0; i < 10; i++ { // nope: i is accessed after the loop (via defer)
		}
	}

	// A use of i within a defer within the loop is also a dealbreaker.
	{
		var i int
		for i = 0; i < 10; i++ { // nope: i is accessed after the loop (via defer)
			defer func() { println(i) }()
		}
	}

	// This (outer) defer is irrelevant.
	defer func() {
		var i int
		for i = range 10 { // want "for loop can be modernized using range over int"
		}
	}()
}

// See go.dev/issue/76880.
func _() (i int) {
	for i = 0; i < 3; i++ { // nope: i is implicitly accessed after the loop
	}
	return
}

func issue74687() {
	for i := range a.ID(10) { // want "for loop can be modernized using range over int"
		println(i)
	}

	for i := range a.ID(13) { // want "for loop can be modernized using range over int"
		println(i)
	}
}

func issue76470() {
	var i, j int
UsedAfter:
	for i = 0; i < 10; i++ { // nope: i is accessed after the loop
		break UsedAfter
	}
	if i == 9 {
		panic("Modernizer changes behavior")
	}

NotUsedAfter:
	for j = range(10) { // want "for loop can be modernized using range over int"
		break NotUsedAfter
	}
}

// Don't allow rewriting of an outer loop when its inner loop modifies the outer
// loop variable.
func issue77034() {
	for i := 0; i < 5; i++ {
		for i = range 10 {
		}
	}
}

func issue77034_define_inner() {
	for range 5 { // want "for loop can be modernized using range over int"
		for i := range 10 { // inner "i" doesn't modify outer "i"
			println(i)
		}
	}
}

type C int32

// Don't add an unneeded type cast if the limit's default type is an integer, and
// the init value is assigned outside the loop, because the compiler can infer the type.
func issue77891() {
	const limit_float = 1e6
	var i int
	for i = range int(limit_float) { // want "for loop can be modernized using range over int"
		println(i)
	}

	var j int64
	for j = range 20 { // want "for loop can be modernized using range over int"
		println(j)
	}

	var c C
	for c = range 10 { 		// want "for loop can be modernized using range over int"
		println(c)
	}

	var ptr uintptr
	for ptr = range 100 { // want "for loop can be modernized using range over int"
		println(ptr)
	}
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/reflecttypefor/reflecttypefor.go
================================================
package reflecttypefor

import (
	"io"
	"reflect"
	"time"
)

type A string

type B[T any] int

var (
	x any
	a A
	b B[int]
	_ = reflect.TypeOf(x)                          // nope (dynamic)
	_ = reflect.TypeOf(0)                          // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(nil)                        // nope (likely a mistake)
	_ = reflect.TypeOf(uint(0))                    // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(error(nil))                 // nope (likely a mistake)
	_ = reflect.TypeOf((*error)(nil))              // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(io.Reader(nil))             // nope (likely a mistake)
	_ = reflect.TypeOf((io.Reader)(nil))           // nope (likely a mistake)
	_ = reflect.TypeOf((*io.Reader)(nil))          // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(*new(time.Time))            // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(time.Time{})                // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(time.Duration(0))           // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(&a)                         // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(&b)                         // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([]io.Reader(nil)).Elem()    // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([]*io.Reader(nil)).Elem()   // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf((*io.Reader)(nil)).Elem()   // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([0]io.Reader{}).Elem()      // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([1]io.Reader{nil}).Elem()   // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([...]io.Reader{}).Elem()    // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf([...]io.Reader{nil}).Elem() // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(chan int(nil)).Elem()       // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(map[string]int(nil)).Elem() // want "reflect.TypeOf call can be simplified using TypeFor"
)

// Eliminate local var if we deleted its last use.
func _() {
	// Test for shadowed nil
	nil := "nil"
	_ = reflect.TypeOf(nil) // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = nil                 // shadowed nil has multiple uses

	var zero string
	_ = reflect.TypeOf(zero) // want "reflect.TypeOf call can be simplified using TypeFor"

	var z2 string
	_ = reflect.TypeOf(z2) // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = z2                 // z2 has multiple uses
}

type T struct {
	f struct {
		A bool
		B int
		C string
	}
}

type S struct {
	f [2]struct {
		A bool
		B int
		C string
	}
}

type R []struct {
	A int
}

type M[T struct{ F int }] int

type P struct {
	f interface {
	}
	g func() // fine length

	long func(a int, b int, c int) (bool, string, int) // too long

	s func(a struct{})

	q func() struct{}
}

func f(t *T, r R, m *M[struct{ F int }], s *S, p *P) {
	// No suggested fix for all of the following because the type is complicated -- e.g. has an unnamed struct,
	// interface, or signature -- so the fix would be more verbose than the original expression.
	// Also because structs and interfaces often acquire new fields and methods, and the type string
	// produced by this modernizer won't get updated automatically, potentially causing a bug.
	_ = reflect.TypeOf(&t.f)
	_ = reflect.TypeOf(r[0])
	_ = reflect.TypeOf(m)
	_ = reflect.TypeOf(&s.f)
	_ = reflect.TypeOf(&p.f)
	_ = reflect.TypeOf(&p.g)
	_ = reflect.TypeOf(&p.long)
	_ = reflect.TypeOf(&p.q)
	_ = reflect.TypeOf(&p.s)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/reflecttypefor/reflecttypefor.go.golden
================================================
package reflecttypefor

import (
	"io"
	"reflect"
	"time"
)

type A string

type B[T any] int

var (
	x any
	a A
	b B[int]
	_ = reflect.TypeOf(x)                // nope (dynamic)
	_ = reflect.TypeFor[int]()           // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(nil)              // nope (likely a mistake)
	_ = reflect.TypeFor[uint]()          // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(error(nil))       // nope (likely a mistake)
	_ = reflect.TypeFor[*error]()        // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeOf(io.Reader(nil))   // nope (likely a mistake)
	_ = reflect.TypeOf((io.Reader)(nil)) // nope (likely a mistake)
	_ = reflect.TypeFor[*io.Reader]()    // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[time.Time]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[time.Time]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[time.Duration]() // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[*A]()            // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[*B[int]]()       // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[*io.Reader]()    // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[io.Reader]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[int]()     // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = reflect.TypeFor[int]()     // want "reflect.TypeOf call can be simplified using TypeFor"
)

// Eliminate local var if we deleted its last use.
func _() {
	// Test for shadowed nil
	nil := "nil"
	_ = reflect.TypeFor[string]() // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = nil                 // shadowed nil has multiple uses
 	
	_ = reflect.TypeFor[string]() // want "reflect.TypeOf call can be simplified using TypeFor"

	var z2 string
	_ = reflect.TypeFor[string]() // want "reflect.TypeOf call can be simplified using TypeFor"
	_ = z2                 // z2 has multiple uses
}

type T struct {
	f struct {
		A bool
		B int
		C string
	}
}

type S struct {
	f [2]struct {
		A bool
		B int
		C string
	}
}

type R []struct {
	A int
}

type M[T struct{ F int }] int

type P struct {
	f interface {
	}
	g func() // fine length

	long func(a int, b int, c int) (bool, string, int) // too long

	s func(a struct{})

	q func() struct{}
}

func f(t *T, r R, m *M[struct{ F int }], s *S, p *P) {
	// No suggested fix for all of the following because the type is complicated -- e.g. has an unnamed struct,
	// interface, or signature -- so the fix would be more verbose than the original expression.
	// Also because structs and interfaces often acquire new fields and methods, and the type string
	// produced by this modernizer won't get updated automatically, potentially causing a bug.
	_ = reflect.TypeOf(&t.f)
	_ = reflect.TypeOf(r[0])
	_ = reflect.TypeOf(m)
	_ = reflect.TypeOf(&s.f)
	_ = reflect.TypeOf(&p.f)
	_ = reflect.TypeOf(&p.g)
	_ = reflect.TypeOf(&p.long)
	_ = reflect.TypeOf(&p.q)
	_ = reflect.TypeOf(&p.s)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicescontains/slicescontains.go
================================================
package slicescontains

import (
	"fmt"
	"slices"
)

var _ = slices.Contains[[]int] // force import of "slices" to avoid duplicate import edits

func nopeNoBreak(slice []int, needle int) {
	for i := range slice {
		if slice[i] == needle {
			println("found")
		}
	}
}

func rangeIndex(slice []int, needle int) {
	for i := range slice { // want "Loop can be simplified using slices.Contains"
		if slice[i] == needle {
			println("found")
			break
		}
	}
}

func rangeValue(slice []int, needle int) {
	for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
		if elem == needle {
			println("found")
			break
		}
	}
}

func returns(slice []int, needle int) {
	for i := range slice { // want "Loop can be simplified using slices.Contains"
		if slice[i] == needle {
			println("found")
			return
		}
	}
}

func assignTrueBreak(slice []int, needle int) {
	found := false
	for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
		if elem == needle {
			found = true
			break
		}
	}
	print(found)
}

func assignFalseBreak(slice []int, needle int) {
	found := true
	for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
		if elem == needle {
			found = false
			break
		}
	}
	print(found)
}

func assignFalseBreakInSelectSwitch(slice []int, needle int) {
	// Exercise RangeStmt in CommClause, CaseClause.
	select {
	default:
		found := false
		for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
			if elem == needle {
				found = true
				break
			}
		}
		print(found)
	}
	switch {
	default:
		found := false
		for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
			if elem == needle {
				found = true
				break
			}
		}
		print(found)
	}
}

func returnTrue(slice []int, needle int) bool {
	for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
		if elem == needle {
			return true
		}
	}
	return false
}

func returnFalse(slice []int, needle int) bool {
	for _, elem := range slice { // want "Loop can be simplified using slices.Contains"
		if elem == needle {
			return false
		}
	}
	return true
}

func containsFunc(slice []int, needle int) bool {
	for _, elem := range slice { // want "Loop can be simplified using slices.ContainsFunc"
		if predicate(elem) {
			return true
		}
	}
	return false
}

func nopeLoopBodyHasFreeContinuation(slice []int, needle int) bool {
	for _, elem := range slice {
		if predicate(elem) {
			if needle == 7 {
				continue // this statement defeats loop elimination
			}
			return true
		}
	}
	return false
}

func generic[T any](slice []T, f func(T) bool) bool {
	for _, elem := range slice { // want "Loop can be simplified using slices.ContainsFunc"
		if f(elem) {
			return true
		}
	}
	return false
}

func predicate(int) bool

// Regression tests for bad fixes when needle
// and haystack have different types (#71313):

func nopeNeedleHaystackDifferentTypes(x any, args []error) {
	for _, arg := range args {
		if arg == x {
			return
		}
	}
}

func nopeNeedleHaystackDifferentTypes2(x error, args []any) {
	for _, arg := range args {
		if arg == x {
			return
		}
	}
}

func nopeVariadicNamedContainsFunc(slice []int) bool {
	for _, elem := range slice {
		if variadicPredicate(elem) {
			return true
		}
	}
	return false
}

func variadicPredicate(int, ...any) bool

func nopeVariadicContainsFunc(slice []int) bool {
	f := func(int, ...any) bool {
		return true
	}
	for _, elem := range slice {
		if f(elem) {
			return true
		}
	}
	return false
}

// Negative test case for implicit C->I conversion
type I interface{ F() }
type C int

func (C) F() {}

func nopeImplicitConversionContainsFunc(slice []C, f func(I) bool) bool {
	for _, elem := range slice {
		if f(elem) { // implicit conversion from C to I
			return true
		}
	}
	return false
}

func nopeTypeParamWidening[T any](slice []T, f func(any) bool) bool {
	for _, elem := range slice {
		if f(elem) { // implicit conversion from T to any
			return true
		}
	}
	return false
}

func issue76210(haystack []string, needle string) bool {
	res := len(haystack) == 0
	for _, elem := range haystack { // want "Loop can be simplified using slices.Contains"
		if needle == elem {
			res = true
			break
		}
	}
	return res
}

func issue76210negation(haystack []string, needle string) bool {
	res := len(haystack) != 0
	for _, elem := range haystack { // want "Loop can be simplified using slices.Contains"
		if needle == elem {
			res = false
			break
		}
	}
	return res
}

func issue77677emptybody(slice []int, needle int) {
	for _, elem := range slice { // nope: would produce "if slices.Contains" with an empty body
		if elem == needle {
			break
		}
	}
}

type Object struct{}

func (o Object) Do() Object { return Object{} }
func (o Object) Print()     { fmt.Println("Hello, World!") }

func issue78149nonboolassign(obj Object, opts ...string) {
	o := obj
	for _, opt := range opts { // want "Loop can be simplified using slices.Contains"
		if opt == "something" {
			o = o.Do()
			break
		}
	}
	o.Print()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicescontains/slicescontains.go.golden
================================================
package slicescontains

import (
	"fmt"
	"slices"
)

var _ = slices.Contains[[]int] // force import of "slices" to avoid duplicate import edits

func nopeNoBreak(slice []int, needle int) {
	for i := range slice {
		if slice[i] == needle {
			println("found")
		}
	}
}

func rangeIndex(slice []int, needle int) {
	if slices.Contains(slice, needle) {
		println("found")
	}
}

func rangeValue(slice []int, needle int) {
	if slices.Contains(slice, needle) {
		println("found")
	}
}

func returns(slice []int, needle int) {
	if slices.Contains(slice, needle) {
		println("found")
		return
	}
}

func assignTrueBreak(slice []int, needle int) {
	found := slices.Contains(slice, needle)
	print(found)
}

func assignFalseBreak(slice []int, needle int) {
	found := !slices.Contains(slice, needle)
	print(found)
}

func assignFalseBreakInSelectSwitch(slice []int, needle int) {
	// Exercise RangeStmt in CommClause, CaseClause.
	select {
	default:
		found := slices.Contains(slice, needle)
		print(found)
	}
	switch {
	default:
		found := slices.Contains(slice, needle)
		print(found)
	}
}

func returnTrue(slice []int, needle int) bool {
	return slices.Contains(slice, needle)
}

func returnFalse(slice []int, needle int) bool {
	return !slices.Contains(slice, needle)
}

func containsFunc(slice []int, needle int) bool {
	return slices.ContainsFunc(slice, predicate)
}

func nopeLoopBodyHasFreeContinuation(slice []int, needle int) bool {
	for _, elem := range slice {
		if predicate(elem) {
			if needle == 7 {
				continue // this statement defeats loop elimination
			}
			return true
		}
	}
	return false
}

func generic[T any](slice []T, f func(T) bool) bool {
	return slices.ContainsFunc(slice, f)
}

func predicate(int) bool

// Regression tests for bad fixes when needle
// and haystack have different types (#71313):

func nopeNeedleHaystackDifferentTypes(x any, args []error) {
	for _, arg := range args {
		if arg == x {
			return
		}
	}
}

func nopeNeedleHaystackDifferentTypes2(x error, args []any) {
	for _, arg := range args {
		if arg == x {
			return
		}
	}
}

func nopeVariadicNamedContainsFunc(slice []int) bool {
	for _, elem := range slice {
		if variadicPredicate(elem) {
			return true
		}
	}
	return false
}

func variadicPredicate(int, ...any) bool

func nopeVariadicContainsFunc(slice []int) bool {
	f := func(int, ...any) bool {
		return true
	}
	for _, elem := range slice {
		if f(elem) {
			return true
		}
	}
	return false
}

// Negative test case for implicit C->I conversion
type I interface{ F() }
type C int

func (C) F() {}

func nopeImplicitConversionContainsFunc(slice []C, f func(I) bool) bool {
	for _, elem := range slice {
		if f(elem) { // implicit conversion from C to I
			return true
		}
	}
	return false
}

func nopeTypeParamWidening[T any](slice []T, f func(any) bool) bool {
	for _, elem := range slice {
		if f(elem) { // implicit conversion from T to any
			return true
		}
	}
	return false
}

func issue76210(haystack []string, needle string) bool {
	res := len(haystack) == 0
	if slices.Contains(haystack, needle) {
		res = true
	}
	return res
}

func issue76210negation(haystack []string, needle string) bool {
	res := len(haystack) != 0
	if slices.Contains(haystack, needle) {
		res = false
	}
	return res
}

func issue77677emptybody(slice []int, needle int) {
	for _, elem := range slice { // nope: would produce "if slices.Contains" with an empty body
		if elem == needle {
			break
		}
	}
}

type Object struct{}

func (o Object) Do() Object { return Object{} }
func (o Object) Print()     { fmt.Println("Hello, World!") }

func issue78149nonboolassign(obj Object, opts ...string) {
	o := obj
	if slices.Contains(opts, "something") {
		o = o.Do()
	}
	o.Print()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicesdelete/slicesdelete.go
================================================
package slicesdelete

var g struct{ f []int }

func h() []int { return []int{} }

var ch chan []int

func slicesdelete(test, other []byte, i int) {
	const k = 1
	_ = append(test[:i], test[i+1:]...) // want "Replace append with slices.Delete"

	_ = append(test[:i+1], test[i+2:]...) // want "Replace append with slices.Delete"

	_ = append(test[:i+1], test[i+1:]...) // not deleting any slice elements

	_ = append(test[:i], test[i-1:]...) // not deleting any slice elements

	_ = append(test[:i-1], test[i:]...) // want "Replace append with slices.Delete"

	_ = append(test[:i-2], test[i+1:]...) // want "Replace append with slices.Delete"

	_ = append(test[:i-2], other[i+1:]...) // different slices "test" and "other"

	_ = append(test[:i-2], other[i+1+k:]...) // cannot verify a < b

	_ = append(test[:i-2], test[11:]...) // cannot verify a < b

	_ = append(test[:1], test[3:]...) // want "Replace append with slices.Delete"

	_ = append(g.f[:i], g.f[i+k:]...) // want "Replace append with slices.Delete"

	_ = append(h()[:i], h()[i+1:]...) // potentially has side effects

	_ = append((<-ch)[:i], (<-ch)[i+1:]...) // has side effects

	_ = append(test[:3], test[i+1:]...) // cannot verify a < b

	_ = append(test[:i-4], test[i-1:]...) // want "Replace append with slices.Delete"

	_ = append(test[:1+2], test[3+4:]...) // want "Replace append with slices.Delete"

	_ = append(test[:1+2], test[i-1:]...) // cannot verify a < b
}

func issue73663(test, other []byte, i int32) {
	const k = 1
	_ = append(test[:i], test[i+1:]...) // want "Replace append with slices.Delete"

	_ = append(test[:i-1], test[i:]...) // want "Replace append with slices.Delete"

	_ = append(g.f[:i], g.f[i+k:]...) // want "Replace append with slices.Delete"

	type int string // int is shadowed, so no offered fix.
	_ = append(test[:i], test[i+1:]...)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicesdelete/slicesdelete.go.golden
================================================
package slicesdelete

import "slices"

var g struct{ f []int }

func h() []int { return []int{} }

var ch chan []int

func slicesdelete(test, other []byte, i int) {
	const k = 1
	_ = slices.Delete(test, i, i+1) // want "Replace append with slices.Delete"

	_ = slices.Delete(test, i+1, i+2) // want "Replace append with slices.Delete"

	_ = append(test[:i+1], test[i+1:]...) // not deleting any slice elements

	_ = append(test[:i], test[i-1:]...) // not deleting any slice elements

	_ = slices.Delete(test, i-1, i) // want "Replace append with slices.Delete"

	_ = slices.Delete(test, i-2, i+1) // want "Replace append with slices.Delete"

	_ = append(test[:i-2], other[i+1:]...) // different slices "test" and "other"

	_ = append(test[:i-2], other[i+1+k:]...) // cannot verify a < b

	_ = append(test[:i-2], test[11:]...) // cannot verify a < b

	_ = slices.Delete(test, 1, 3) // want "Replace append with slices.Delete"

	_ = slices.Delete(g.f, i, i+k) // want "Replace append with slices.Delete"

	_ = append(h()[:i], h()[i+1:]...) // potentially has side effects

	_ = append((<-ch)[:i], (<-ch)[i+1:]...) // has side effects

	_ = append(test[:3], test[i+1:]...) // cannot verify a < b

	_ = slices.Delete(test, i-4, i-1) // want "Replace append with slices.Delete"

	_ = slices.Delete(test, 1+2, 3+4) // want "Replace append with slices.Delete"

	_ = append(test[:1+2], test[i-1:]...) // cannot verify a < b
}

func issue73663(test, other []byte, i int32) {
	const k = 1
	_ = slices.Delete(test, int(i), int(i+1)) // want "Replace append with slices.Delete"

	_ = slices.Delete(test, int(i-1), int(i)) // want "Replace append with slices.Delete"

	_ = slices.Delete(g.f, int(i), int(i+k)) // want "Replace append with slices.Delete"

	type int string // int is shadowed, so no offered fix.
	_ = append(test[:i], test[i+1:]...)
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/slicessort/slicessort.go
================================================
package slicessort

import "sort"

type myint int

func _(s []myint) {
	sort.Slice(s, func(i, j int) bool { return s[i] < s[j] }) // want "sort.Slice can be modernized using slices.Sort"
}

func _(x *struct{ s []int }) {
	sort.Slice(x.s, func(first, second int) bool { return x.s[first] < x.s[second] }) // want "sort.Slice can be modernized using slices.Sort"
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[i] > s[j] }) // nope: wrong comparison operator
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[j] < s[i] }) // nope: wrong index var
}

func _(sense bool, s2 []struct{ x int }) {
	sort.Slice(s2, func(i, j int) bool { return s2[i].x < s2[j].x }) // nope: not a simple index operation

	// Regression test for a crash: the sole statement of a
	// comparison func body is not necessarily a return!
	sort.Slice(s2, func(i, j int) bool {
		if sense {
			return s2[i].x < s2[j].x
		} else {
			return s2[i].x > s2[j].x
		}
	})
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicessort/slicessort.go.golden
================================================
package slicessort

import "slices"

import "sort"

type myint int

func _(s []myint) {
	slices.Sort(s) // want "sort.Slice can be modernized using slices.Sort"
}

func _(x *struct{ s []int }) {
	slices.Sort(x.s) // want "sort.Slice can be modernized using slices.Sort"
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[i] > s[j] }) // nope: wrong comparison operator
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[j] < s[i] }) // nope: wrong index var
}

func _(sense bool, s2 []struct{ x int }) {
	sort.Slice(s2, func(i, j int) bool { return s2[i].x < s2[j].x }) // nope: not a simple index operation

	// Regression test for a crash: the sole statement of a
	// comparison func body is not necessarily a return!
	sort.Slice(s2, func(i, j int) bool {
		if sense {
			return s2[i].x < s2[j].x
		} else {
			return s2[i].x > s2[j].x			
		}
	})
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicessort/slicessort_dot.go
================================================
package slicessort

import (
	. "slices"
	"sort"
)

func _(s []myint) {
	sort.Slice(s, func(i, j int) bool { return s[i] < s[j] }) // want "sort.Slice can be modernized using slices.Sort"
}

func _(x *struct{ s []int }) {
	sort.Slice(x.s, func(first, second int) bool { return x.s[first] < x.s[second] }) // want "sort.Slice can be modernized using slices.Sort"
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[i] > s[j] }) // nope: wrong comparison operator
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[j] < s[i] }) // nope: wrong index var
}

func _(s2 []struct{ x int }) {
	sort.Slice(s2, func(i, j int) bool { return s2[i].x < s2[j].x }) // nope: not a simple index operation
}

func _() { Clip([]int{}) }


================================================
FILE: go/analysis/passes/modernize/testdata/src/slicessort/slicessort_dot.go.golden
================================================
package slicessort

import (
	. "slices"
	"sort"
)

func _(s []myint) {
	Sort(s) // want "sort.Slice can be modernized using slices.Sort"
}

func _(x *struct{ s []int }) {
	Sort(x.s) // want "sort.Slice can be modernized using slices.Sort"
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[i] > s[j] }) // nope: wrong comparison operator
}

func _(s []int) {
	sort.Slice(s, func(i, j int) bool { return s[j] < s[i] }) // nope: wrong index var
}

func _(s2 []struct{ x int }) {
	sort.Slice(s2, func(i, j int) bool { return s2[i].x < s2[j].x }) // nope: not a simple index operation
}

func _() { Clip([]int{}) }


================================================
FILE: go/analysis/passes/modernize/testdata/src/splitseq/splitseq.go
================================================
//go:build go1.24

package splitseq

import (
	"bytes"
	"strings"
)

func _() {
	for _, line := range strings.Split("", "") { // want "Ranging over SplitSeq is more efficient"
		println(line)
	}
	for i, line := range strings.Split("", "") { // nope: uses index var
		println(i, line)
	}
	for i, _ := range strings.Split("", "") { // nope: uses index var
		println(i)
	}
	for i := range strings.Split("", "") { // nope: uses index var
		println(i)
	}
	for _ = range strings.Split("", "") { // want "Ranging over SplitSeq is more efficient"
	}
	for range strings.Split("", "") { // want "Ranging over SplitSeq is more efficient"
	}
	for range bytes.Split(nil, nil) { // want "Ranging over SplitSeq is more efficient"
	}
	{
		lines := strings.Split("", "") // want "Ranging over SplitSeq is more efficient"
		for _, line := range lines {
			println(line)
		}
	}
	{
		lines := strings.Split("", "") // nope: lines is used not just by range
		for _, line := range lines {
			println(line)
		}
		println(lines)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/splitseq/splitseq.go.golden
================================================
//go:build go1.24

package splitseq

import (
	"bytes"
	"strings"
)

func _() {
	for line := range strings.SplitSeq("", "") { // want "Ranging over SplitSeq is more efficient"
		println(line)
	}
	for i, line := range strings.Split("", "") { // nope: uses index var
		println(i, line)
	}
	for i, _ := range strings.Split("", "") { // nope: uses index var
		println(i)
	}
	for i := range strings.Split("", "") { // nope: uses index var
		println(i)
	}
	for range strings.SplitSeq("", "") { // want "Ranging over SplitSeq is more efficient"
	}
	for range strings.SplitSeq("", "") { // want "Ranging over SplitSeq is more efficient"
	}
	for range bytes.SplitSeq(nil, nil) { // want "Ranging over SplitSeq is more efficient"
	}
	{
		lines := strings.SplitSeq("", "") // want "Ranging over SplitSeq is more efficient"
		for line := range lines {
			println(line)
		}
	}
	{
		lines := strings.Split("", "") // nope: lines is used not just by range
		for _, line := range lines {
			println(line)
		}
		println(lines)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/splitseq/splitseq_go123.go
================================================
package splitseq


================================================
FILE: go/analysis/passes/modernize/testdata/src/stditerators/stditerators.go
================================================
package stditerators

import (
	"go/types"
	"reflect"
)

func _(tuple *types.Tuple) {
	for i := 0; i < tuple.Len(); i++ { // want "Len/At loop can simplified using Tuple.Variables iteration"
		print(tuple.At(i))
	}
}

func _(scope *types.Scope) {
	for i := 0; i < scope.NumChildren(); i++ { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
		print(scope.Child(i))
	}
	{
		// tests of shadowing of preferred name at def
		const child = 0
		for i := 0; i < scope.NumChildren(); i++ { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			print(scope.Child(i))
		}
		for i := 0; i < scope.NumChildren(); i++ { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			print(scope.Child(i), child)
		}
	}
	{
		for i := 0; i < scope.NumChildren(); i++ {
			const child = 0 // nope: shadowing of fresh name at use
			print(scope.Child(i))
		}
	}
	{
		for i := 0; i < scope.NumChildren(); i++ { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			elem := scope.Child(i) // => preferred name = "elem"
			print(elem)
		}
	}
	{
		for i := 0; i < scope.NumChildren(); i++ { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			first := scope.Child(0) // the name heuristic should not be fooled by this
			print(first, scope.Child(i))
		}
	}
}

func _(union, union2 *types.Union) {
	for i := 0; i < union.Len(); i++ { // want "Len/Term loop can simplified using Union.Terms iteration"
		print(union.Term(i))
		print(union.Term(i))
	}
	for i := union.Len() - 1; i >= 0; i-- { // nope: wrong loop form
		print(union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: wrong loop form
		print(union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: use of i not in x.At(i)
		print(i, union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: x.At and x.Len have different receivers
		print(i, union2.Term(i))
	}
}

func _(tuple *types.Tuple) {
	for i := 0; i < tuple.Len(); i++ { // want "Len/At loop can simplified using Tuple.Variables iteration"
		if foo := tuple.At(i); true { // => preferred name = "foo"
			print(foo)
		}
		bar := tuple.At(i)
		print(bar)
	}
	{
		// The name v is already declared, but not
		// used in the loop, so we can use it again.
		v := 1
		print(v)

		for i := 0; i < tuple.Len(); i++ { // want "Len/At loop can simplified using Tuple.Variables iteration"
			print(tuple.At(i))
		}
	}
	{
		// The name v is used from the loop, so
		// we must choose a fresh name.
		v := 1
		for i := 0; i < tuple.Len(); i++ { // want "Len/At loop can simplified using Tuple.Variables iteration"
			print(tuple.At(i), v)
		}
	}
}

func _(t reflect.Type) {
	for i := 0; i < t.NumField(); i++ { // want "NumField/Field loop can simplified using Type.Fields iteration"
		print(t.Field(i))
	}
	for i := 0; i < t.NumMethod(); i++ { // want "NumMethod/Method loop can simplified using Type.Methods iteration"
		print(t.Method(i))
	}
	for i := 0; i < t.NumIn(); i++ { // want "NumIn/In loop can simplified using Type.Ins iteration"
		print(t.In(i))
	}
	for i := 0; i < t.NumOut(); i++ { // want "NumOut/Out loop can simplified using Type.Outs iteration"
		print(t.Out(i))
	}
}

func _(v reflect.Value) {
	for i := 0; i < v.NumField(); i++ { // want "NumField/Field loop can simplified using Value.Fields iteration"
		print(v.Field(i))
	}
	// Ideally we would use both parts of Value.Field's iter.Seq2 here.
	for i := 0; i < v.NumField(); i++ {
		print(v.Field(i), v.Type().Field(i)) // nope
	}
	for i := 0; i < v.NumMethod(); i++ { // want "NumMethod/Method loop can simplified using Value.Methods iteration"
		print(v.Method(i))
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stditerators/stditerators.go.golden
================================================
package stditerators

import (
	"go/types"
	"reflect"
)

func _(tuple *types.Tuple) {
	for v := range tuple.Variables() { // want "Len/At loop can simplified using Tuple.Variables iteration"
		print(v)
	}
}

func _(scope *types.Scope) {
	for child := range scope.Children() { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
		print(child)
	}
	{
		// tests of shadowing of preferred name at def
		const child = 0
		for child := range scope.Children() { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			print(child)
		}
		for child0 := range scope.Children() { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			print(child0, child)
		}
	}
	{
       		for i := 0; i < scope.NumChildren(); i++ {
       			const child = 0 // nope: shadowing of fresh name at use
       			print(scope.Child(i))
       		}
       	}
	{
		for elem := range scope.Children() { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			elem := elem // => preferred name = "elem"
			print(elem)
		}
	}
	{
		for child := range scope.Children() { // want "NumChildren/Child loop can simplified using Scope.Children iteration"
			first := scope.Child(0) // the name heuristic should not be fooled by this
			print(first, child)
		}
	}
}

func _(union, union2 *types.Union) {
	for term := range union.Terms() { // want "Len/Term loop can simplified using Union.Terms iteration"
		print(term)
		print(term)
	}
	for i := union.Len() - 1; i >= 0; i-- { // nope: wrong loop form
		print(union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: wrong loop form
		print(union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: use of i not in x.At(i)
		print(i, union.Term(i))
	}
	for i := 0; i <= union.Len(); i++ { // nope: x.At and x.Len have different receivers
		print(i, union2.Term(i))
	}
}

func _(tuple *types.Tuple) {
	for foo := range tuple.Variables() { // want "Len/At loop can simplified using Tuple.Variables iteration"
		if foo := foo; true { // => preferred name = "foo"
			print(foo)
		}
		bar := foo
		print(bar)
	}
	{
		// The name v is already declared, but not
		// used in the loop, so we can use it again.
		v := 1
		print(v)

		for v := range tuple.Variables() { // want "Len/At loop can simplified using Tuple.Variables iteration"
			print(v)
		}
	}
	{
		// The name v is used from the loop, so
		// we must choose a fresh name.
		v := 1
		for v0 := range tuple.Variables() { // want "Len/At loop can simplified using Tuple.Variables iteration"
			print(v0, v)
		}
	}
}

func _(t reflect.Type) {
	for field := range t.Fields() { // want "NumField/Field loop can simplified using Type.Fields iteration"
		print(field)
	}
	for method := range t.Methods() { // want "NumMethod/Method loop can simplified using Type.Methods iteration"
		print(method)
	}
	for in := range t.Ins() { // want "NumIn/In loop can simplified using Type.Ins iteration"
		print(in)
	}
	for out := range t.Outs() { // want "NumOut/Out loop can simplified using Type.Outs iteration"
		print(out)
	}
}

func _(v reflect.Value) {
	for _, field := range v.Fields() { // want "NumField/Field loop can simplified using Value.Fields iteration"
		print(field)
	}
	// Ideally we would use both parts of Value.Field's iter.Seq2 here.
	for i := 0; i < v.NumField(); i++ {
		print(v.Field(i), v.Type().Field(i)) // nope
	}
	for _, method := range v.Methods() { // want "NumMethod/Method loop can simplified using Value.Methods iteration"
		print(method)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringsbuilder/stringsbuilder.go
================================================
package stringsbuilder

import "strings"

// basic test
func _() {
	var s string
	s += "before"
	for range 10 {
		s += "in" // want "using string \\+= string in a loop is inefficient"
		s += "in2"
	}
	s += "after"
	print(s)
}

// with initializer
func _() {
	var s = "a"
	for range 10 {
		s += "b" // want "using string \\+= string in a loop is inefficient"
	}
	print(s)
}

// with empty initializer
func _() {
	var s = ""
	for range 10 {
		s += "b" // want "using string \\+= string in a loop is inefficient"
	}
	print(s)
}

// with short decl
func _() {
	s := "a"
	for range 10 {
		s += "b" // want "using string \\+= string in a loop is inefficient"
	}
	print(s)
}

// with short decl and empty initializer
func _() {
	s := ""
	for range 10 {
		s += "b" // want "using string \\+= string in a loop is inefficient"
	}
	print(s)
}

// nope: += must appear at least once within a loop.
func _() {
	var s string
	s += "a"
	s += "b"
	s += "c"
	print(s)
}

// nope: the declaration of s is not in a block.
func _() {
	if s := "a"; true {
		for range 10 {
			s += "x"
		}
		print(s)
	}
}

// in a switch (special case of "in a block" logic)
func _() {
	switch {
	default:
		s := "a"
		for range 10 {
			s += "b" // want "using string \\+= string in a loop is inefficient"
		}
		print(s)
	}
}

// nope: don't handle direct assignments to the string  (only +=).
func _(x string) string {
	var s string
	s = x
	for range 3 {
		s += "" + x
	}
	return s
}

// Regression test for bug in a GenDecl with parens.
func issue75318(slice []string) string {
	var (
		msg string
	)
	for _, s := range slice {
		msg += s // want "using string \\+= string in a loop is inefficient"
	}
	return msg
}

// Regression test for https://go.dev/issue/76983.
// We offer only the first fix if the second would overlap.
// This is an ad-hoc mitigation of the more general issue #76476.
func _(slice []string) string {
	a := "12"
	for range 2 {
		a += "34" // want "using string \\+= string in a loop is inefficient"
	}
	b := "56"
	for range 2 {
		b += "78"
	}
	a += b
	return a
}
func _(slice []string) string {
	var a strings.Builder
	a.WriteString("12")
	for range 2 {
		a.WriteString("34")
	}
	b := "56"
	for range 2 {
		b += "78" // want "using string \\+= string in a loop is inefficient"
	}
	a.WriteString(b)
	return a.String()
}

// Regression test for go.dev/issue/76934, which mutilated the var decl.
func stringDeclaredWithVarDecl() {
	var (
		before int // this is ok
		str    = "hello world"
	)
	for range 100 {
		str += "!" // want "using string \\+= string in a loop is inefficient"
	}
	println(before, str)
}

func nopeStringIsNotLastValueSpecInVarDecl() {
	var (
		str   = "hello world"
		after int // this defeats the transformation
	)
	for range 100 {
		str += "!" // nope
	}
	println(str, after)
}

// Regression test for go.dev/issue/77659.
// Multiple rvalue uses of the accumulated string should all be converted.
func _() {
	acc := "s1"
	for _, s := range []string{"foo", "bar"} {
		acc += s // want "using string \\+= string in a loop is inefficient"
	}
	_ = acc
	_ = acc + "footer2"
}

// Regression test for go.dev/issue/77659 (negative case).
// += after an rvalue use should still be rejected.
func _() {
	var s string
	for _, x := range []string{"a", "b"} {
		s += x
	}
	print(s)
	s += "extra" // nope: += after rvalue use
	print(s)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringsbuilder/stringsbuilder.go.golden
================================================
package stringsbuilder

import "strings"

// basic test
func _() {
	var s strings.Builder
	s.WriteString("before")
	for range 10 {
		s.WriteString("in") // want "using string \\+= string in a loop is inefficient"
		s.WriteString("in2")
	}
	s.WriteString("after")
	print(s.String())
}

// with initializer
func _() {
	var s strings.Builder
	s.WriteString("a")
	for range 10 {
		s.WriteString("b") // want "using string \\+= string in a loop is inefficient"
	}
	print(s.String())
}

// with empty initializer
func _() {
	var s strings.Builder
	for range 10 {
		s.WriteString("b") // want "using string \\+= string in a loop is inefficient"
	}
	print(s.String())
}

// with short decl
func _() {
	var s strings.Builder
	s.WriteString("a")
	for range 10 {
		s.WriteString("b") // want "using string \\+= string in a loop is inefficient"
	}
	print(s.String())
}

// with short decl and empty initializer
func _() {
	var s strings.Builder
	for range 10 {
		s.WriteString("b") // want "using string \\+= string in a loop is inefficient"
	}
	print(s.String())
}

// nope: += must appear at least once within a loop.
func _() {
	var s string
	s += "a"
	s += "b"
	s += "c"
	print(s)
}

// nope: the declaration of s is not in a block.
func _() {
	if s := "a"; true {
		for range 10 {
			s += "x"
		}
		print(s)
	}
}

// in a switch (special case of "in a block" logic)
func _() {
	switch {
	default:
		var s strings.Builder
		s.WriteString("a")
		for range 10 {
			s.WriteString("b") // want "using string \\+= string in a loop is inefficient"
		}
		print(s.String())
	}
}

// nope: don't handle direct assignments to the string  (only +=).
func _(x string) string {
	var s string
	s = x
	for range 3 {
		s += "" + x
	}
	return s
}

// Regression test for bug in a GenDecl with parens.
func issue75318(slice []string) string {
	var (
		msg strings.Builder
	)
	for _, s := range slice {
		msg.WriteString(s) // want "using string \\+= string in a loop is inefficient"
	}
	return msg.String()
}

// Regression test for https://go.dev/issue/76983.
// We offer only the first fix if the second would overlap.
// This is an ad-hoc mitigation of the more general issue #76476.
func _(slice []string) string {
	var a strings.Builder; a.WriteString("12")
	for range 2 {
		a.WriteString("34") // want "using string \\+= string in a loop is inefficient"
	}
	b := "56"
	for range 2 {
		b += "78"
	}
	a.WriteString(b)
	return a.String()
}
func _(slice []string) string {
	var a strings.Builder
	a.WriteString("12")
	for range 2 {
		a.WriteString("34")
	}
	var b strings.Builder
	b.WriteString("56")
	for range 2 {
		b.WriteString("78") // want "using string \\+= string in a loop is inefficient"
	}
	a.WriteString(b.String())
	return a.String()
}

// Regression test for go.dev/issue/76934, which mutilated the var decl.
func stringDeclaredWithVarDecl() {
	var (
		before int // this is ok
		str strings.Builder
	)
	str.WriteString("hello world")
	for range 100 {
		str.WriteString("!") // want "using string \\+= string in a loop is inefficient"
	}
	println(before, str.String())
}

func nopeStringIsNotLastValueSpecInVarDecl() {
	var (
		str   = "hello world"
		after int // this defeats the transformation
	)
	for range 100 {
		str += "!" // nope
	}
	println(str, after)
}

// Regression test for go.dev/issue/77659.
// Multiple rvalue uses of the accumulated string should all be converted.
func _() {
	var acc strings.Builder
	acc.WriteString("s1")
	for _, s := range []string{"foo", "bar"} {
		acc.WriteString(s) // want "using string \\+= string in a loop is inefficient"
	}
	_ = acc.String()
	_ = acc.String() + "footer2"
}

// Regression test for go.dev/issue/77659 (negative case).
// += after an rvalue use should still be rejected.
func _() {
	var s string
	for _, x := range []string{"a", "b"} {
		s += x
	}
	print(s)
	s += "extra" // nope: += after rvalue use
	print(s)
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscut/stringscut.go
================================================
package stringscut

import (
	"bytes"
	"strings"
)

func basic(s string) bool {
	s = "reassigned"
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i >= 0 {
		print(s[:i])
	}
	return i >= 0
}

func basic_contains(s string) bool {
	s = "reassigned"
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Contains"
	return i >= 0
}

func contains_variety(s, sub string) {
	i := strings.Index(s, sub) // want "strings.Index can be simplified using strings.Contains"
	if i >= 0 {
		print("found")
	}
	if i < 0 {
		print("not found")
	}
	if i <= -1 {
		print("not found")
	}
}

func basic_contains_bytes(s string) bool {
	i := strings.IndexByte(s, '=') // want "strings.IndexByte can be simplified using strings.Contains"
	return i < 0
}

func basic_contains_bytes_byte(s []byte) bool {
	i := bytes.IndexByte(s, 22) // want "bytes.IndexByte can be simplified using bytes.Contains"
	return i < 0
}

func skip_var_decl(s string) bool {
	var i int
	i = strings.Index(s, "=") // don't modernize - i might be reassigned
	print(s[:i])
	return i >= 0
}

func basic_substr_arg(s string, substr string) bool {
	i := strings.Index(s, substr) // want "strings.Index can be simplified using strings.Cut"
	if i >= 0 {
		print(s[i+len(substr):])
	}
	return i >= 0
}

func wrong_len_arg(s string, substr string) bool {
	i := strings.Index(s, substr) // don't modernize since i+len(s) is not valid
	print(s[i+len(s):])
	return i >= 0
}

func basic_strings_byte(s string) bool {
	i := strings.IndexByte(s, '+') // want "strings.IndexByte can be simplified using strings.Cut"
	if i >= 0 {
		print(s[:i])
	}
	return i >= 0
}

func basic_strings_byte_int(s string) bool {
	i := strings.IndexByte(s, 55) // want "strings.IndexByte can be simplified using strings.Cut"
	if i >= 0 {
		print(s[:i])
	}
	return i >= 0
}

func basic_strings_byte_var(s string) bool {
	b := byte('b')
	i := strings.IndexByte(s, b) // want "strings.IndexByte can be simplified using strings.Cut"
	if i >= 0 {
		print(s[:i])
	}
	return i >= 0
}

func basic_bytes(b []byte) []byte {
	i := bytes.Index(b, []byte("str")) // want "bytes.Index can be simplified using bytes.Cut"
	if i >= 0 {
		return b[:i]
	} else {
		return b[i+3:]
	}
}

func basic_index_bytes(b []byte) string {
	i := bytes.IndexByte(b, 's') // don't modernize: b[i+1:] in else is not guarded
	if i >= 0 {
		return string(b[:i])
	} else {
		return string(b[i+1:])
	}
}

func const_substr_len(s string) bool {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i >= 0 {
		r := s[i+len("="):]
		return len(r) > 0
	}
	return false
}

func const_for_len(s string) bool {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i >= 0 {
		r := s[i+1:]
		return len(r) > 0
	}
	return false
}

func index(s string) bool {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i < 0 {
		return false
	}
	if i >= 0 {
		return true
	}
	print(s[:i])
	return true
}

func index_flipped(s string) bool {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if 0 > i {
		return false
	}
	if 0 <= i {
		return true
	}
	print(s[:i])
	return true
}

func invalid_index(s string) bool {
	i := strings.Index(s, "=") // don't modernize since i is used in an "invalid" binaryexpr
	if 0 > i {
		return false
	}
	if i < 10 {
		return true
	}
	return true
}

func invalid_slice(s string) string {
	i := strings.Index(s, "=") // don't modernize since i is used in an "invalid" slice index
	if i >= 0 {
		return s[i+4:]
	}
	return ""
}

func index_and_before_after(s string) string {
	substr := "="
	i := strings.Index(s, substr) // don't modernize: s[i+len(substr):] and s[len(substr)+i:] not nonneg-guarded
	if i == -1 {
		print("test")
	}
	if i < 0 {
		return ""
	} else {
		if i >= 0 {
			return s[:i]
		} else {
			return s[i+len(substr):]
		}
	}
	if -1 == i {
		return s[len(substr)+i:]
	}
	return "final"
}

func idx_var_init(s string) (string, string) {
	var idx = strings.Index(s, "=") // don't modernize: s[0:idx] is not guarded
	return s[0:idx], s
}

func idx_reassigned(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets reassigned
	idx = 10
	return s[:idx]
}

func idx_printed(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx is used
	print(idx)
	return s[:idx]
}

func idx_aliased(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets aliased
	i := idx
	return s[:i]
}

func idx_aliased_var(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets aliased
	var i = idx
	print(i)
	return s[:idx]
}

func s_modified(s string) string {
	idx := strings.Index(s, "=") // don't modernize since s gets modified
	s = "newstring"
	return s[:idx]
}

func s_modified_no_params() string {
	s := "string"
	idx := strings.Index(s, "=") // don't modernize since s gets modified
	s = "newstring"
	return s[:idx]
}

func s_in_func_call() string {
	s := "string"
	substr := "substr"
	idx := strings.Index(s, substr) // don't modernize: s[:idx] is not guarded
	function(s)
	return s[:idx]
}

func s_pointer() string {
	s := "string"
	idx := strings.Index(s, "s")
	ptr := &s // don't modernize since s may get modified
	reference_str(ptr)
	return s[:idx]
}

func s_pointer_before_call() string {
	s := "string"
	ptr := &s // don't modernize since s may get modified
	reference_str(ptr)
	idx := strings.Index(s, "s")
	return s[:idx]
}

func idx_used_before(s string, sub string) string {
	var index int
	reference_int(&index)
	index = strings.Index(s, sub) // don't modernize since index may get modified
	blank()
	if index >= 0 {
		return s[:index]
	}
	return ""
}

func idx_used_other_substr(s string, sub string) string {
	otherstr := "other"
	i := strings.Index(s, sub)
	print(otherstr[:i]) // don't modernize since i used in another slice expr
	if i >= 0 {
		return s[:i]
	} else {
		return ""
	}
}

func idx_gtr_zero_invalid(s string, sub string) string {
	i := strings.Index(s, sub)
	if i > 0 { // don't modernize since this is a stronger claim than i >= 0
		return s[:i]
	}
	return ""
}

func idx_gtreq_one_invalid(s string, sub string) string {
	i := strings.Index(s, sub)
	if i >= 1 { // don't modernize since this is a stronger claim than i >= 0
		return s[:i]
	}
	return ""
}

func idx_gtr_negone(s string, sub string) string {
	i := strings.Index(s, sub) // want "strings.Index can be simplified using strings.Cut"
	if i > -1 {
		return s[:i]
	}
	if i != -1 {
		return s
	}
	return ""
}

// Regression test for a crash (https://go.dev/issue/77208)
func idx_call() {
	i := bytes.Index(b(), []byte(""))
	_ = i
}

// Fix for golang/go#77566
func multipleCallsSameScope(s string) (bool, bool) {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i != -1 {
		print(s[:i])
	}
	j := strings.Index(s, "-") // want "strings.Index can be simplified using strings.Cut"
	if j != -1 {
		print(s[:j])
	}
	return i >= 0, j >= 0
}

func shadowing(s string) string {
	ok := "true"
	before := "before"
	print(before)              // declared within scope but not used after the index call, so no fresh name
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	print(ok)
	if i >= 0 {
		print(s[:i])
		print(i >= 0)
		return s[i+1:]
	}
	return ""
}

func foreshadowing(s string) string {
	i := strings.Index(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if i != -1 {
		return s[i+1:]
	}
	// Generate a fresh name for ok because it is used within the scope after the Index call.
	ok, m := true, "m"
	if ok {
		return m
	}
	if i != -1 {
		return s
	}
	return ""
}

func b() []byte {
	return nil
}

func function(s string) {}

func reference_str(s *string) {}

func reference_int(i *int) {}

func blank() {}

// Regression test for unguarded slice uses (https://go.dev/issue/77737).
// The s[colon+1:] usage outside the "if" relies on -1+1=0 to return the full
// string when the separator is absent. Rewriting to "after" would return "".
func unguarded_after_slice(s string) (int, string) {
	colon := strings.Index(s, ":")
	if colon != -1 {
		print(s[:colon])
	}
	return colon, s[colon+1:] // don't modernize: s[colon+1:] not guarded
}

// Same as above but with the guard using i < 0.
func unguarded_after_slice_negcheck(s string) string {
	i := strings.Index(s, ":")
	if i < 0 {
		print("not found")
	}
	return s[i+1:] // don't modernize: s[i+1:] not guarded
}

// Safe: both slice uses are inside the nonneg guard.
func guarded_both_slices(s string) (string, string) {
	i := strings.Index(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if i >= 0 {
		return s[:i], s[i+1:]
	}
	return "", s
}

// Safe: slice uses after early-return negative check.
func guarded_early_return(s string) (string, string) {
	i := strings.Index(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if i < 0 {
		return "", s
	}
	return s[:i], s[i+1:]
}

// Safe: slice uses in else of negative check.
func guarded_neg_else(s string) (string, string) {
	i := strings.Index(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if i == -1 {
		return "", s
	} else {
		return s[:i], s[i+1:]
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscut/stringscut.go.golden
================================================
package stringscut

import (
	"bytes"
	"strings"
)

func basic(s string) bool {
	s = "reassigned"
	before, _, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if ok {
		print(before)
	}
	return ok
}

func basic_contains(s string) bool {
	s = "reassigned"
	found := strings.Contains(s, "=") // want "strings.Index can be simplified using strings.Contains"
	return found
}

func contains_variety(s, sub string) {
	found := strings.Contains(s, sub) // want "strings.Index can be simplified using strings.Contains"
	if found {
		print("found")
	}
	if !found {
		print("not found")
	}
	if !found {
		print("not found")
	}
}

func basic_contains_bytes(s string) bool {
	found := strings.Contains(s, "=") // want "strings.IndexByte can be simplified using strings.Contains"
	return !found
}

func basic_contains_bytes_byte(s []byte) bool {
	found := bytes.Contains(s, []byte{22}) // want "bytes.IndexByte can be simplified using bytes.Contains"
	return !found
}

func skip_var_decl(s string) bool {
	var i int
	i = strings.Index(s, "=") // don't modernize - i might be reassigned
	print(s[:i])
	return i >= 0
}

func basic_substr_arg(s string, substr string) bool {
	_, after, ok := strings.Cut(s, substr) // want "strings.Index can be simplified using strings.Cut"
	if ok {
		print(after)
	}
	return ok
}

func wrong_len_arg(s string, substr string) bool {
	i := strings.Index(s, substr) // don't modernize since i+len(s) is not valid
	print(s[i+len(s):])
	return i >= 0
}

func basic_strings_byte(s string) bool {
	before, _, ok := strings.Cut(s, "+") // want "strings.IndexByte can be simplified using strings.Cut"
	if ok {
		print(before)
	}
	return ok
}

func basic_strings_byte_int(s string) bool {
	before, _, ok := strings.Cut(s, "7") // want "strings.IndexByte can be simplified using strings.Cut"
	if ok {
		print(before)
	}
	return ok
}

func basic_strings_byte_var(s string) bool {
	b := byte('b')
	before, _, ok := strings.Cut(s, string(b)) // want "strings.IndexByte can be simplified using strings.Cut"
	if ok {
		print(before)
	}
	return ok
}

func basic_bytes(b []byte) []byte {
	before, after, ok := bytes.Cut(b, []byte("str")) // want "bytes.Index can be simplified using bytes.Cut"
	if ok {
		return before
	} else {
		return after
	}
}

func basic_index_bytes(b []byte) string {
	i := bytes.IndexByte(b, 's') // don't modernize: b[i+1:] in else is not guarded
	if i >= 0 {
		return string(b[:i])
	} else {
		return string(b[i+1:])
	}
}

func const_substr_len(s string) bool {
	_, after, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if ok {
		r := after
		return len(r) > 0
	}
	return false
}

func const_for_len(s string) bool {
	_, after, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if ok {
		r := after
		return len(r) > 0
	}
	return false
}

func index(s string) bool {
	before, _, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if !ok {
		return false
	}
	if ok {
		return true
	}
	print(before)
	return true
}

func index_flipped(s string) bool {
	before, _, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if !ok {
		return false
	}
	if ok {
		return true
	}
	print(before)
	return true
}

func invalid_index(s string) bool {
	i := strings.Index(s, "=") // don't modernize since i is used in an "invalid" binaryexpr
	if 0 > i {
		return false
	}
	if i < 10 {
		return true
	}
	return true
}

func invalid_slice(s string) string {
	i := strings.Index(s, "=") // don't modernize since i is used in an "invalid" slice index
	if i >= 0 {
		return s[i+4:]
	}
	return ""
}

func index_and_before_after(s string) string {
	substr := "="
	i := strings.Index(s, substr) // don't modernize: s[i+len(substr):] and s[len(substr)+i:] not nonneg-guarded
	if i == -1 {
		print("test")
	}
	if i < 0 {
		return ""
	} else {
		if i >= 0 {
			return s[:i]
		} else {
			return s[i+len(substr):]
		}
	}
	if -1 == i {
		return s[len(substr)+i:]
	}
	return "final"
}

func idx_var_init(s string) (string, string) {
	var idx = strings.Index(s, "=") // don't modernize: s[0:idx] is not guarded
	return s[0:idx], s
}

func idx_reassigned(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets reassigned
	idx = 10
	return s[:idx]
}

func idx_printed(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx is used
	print(idx)
	return s[:idx]
}

func idx_aliased(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets aliased
	i := idx
	return s[:i]
}

func idx_aliased_var(s string) string {
	idx := strings.Index(s, "=") // don't modernize since idx gets aliased
	var i = idx
	print(i)
	return s[:idx]
}

func s_modified(s string) string {
	idx := strings.Index(s, "=") // don't modernize since s gets modified
	s = "newstring"
	return s[:idx]
}

func s_modified_no_params() string {
	s := "string"
	idx := strings.Index(s, "=") // don't modernize since s gets modified
	s = "newstring"
	return s[:idx]
}

func s_in_func_call() string {
	s := "string"
	substr := "substr"
	idx := strings.Index(s, substr) // don't modernize: s[:idx] is not guarded
	function(s)
	return s[:idx]
}

func s_pointer() string {
	s := "string"
	idx := strings.Index(s, "s")
	ptr := &s // don't modernize since s may get modified
	reference_str(ptr)
	return s[:idx]
}

func s_pointer_before_call() string {
	s := "string"
	ptr := &s // don't modernize since s may get modified
	reference_str(ptr)
	idx := strings.Index(s, "s")
	return s[:idx]
}

func idx_used_before(s string, sub string) string {
	var index int
	reference_int(&index)
	index = strings.Index(s, sub) // don't modernize since index may get modified
	blank()
	if index >= 0 {
		return s[:index]
	}
	return ""
}

func idx_used_other_substr(s string, sub string) string {
	otherstr := "other"
	i := strings.Index(s, sub)
	print(otherstr[:i]) // don't modernize since i used in another slice expr
	if i >= 0 {
		return s[:i]
	} else {
		return ""
	}
}

func idx_gtr_zero_invalid(s string, sub string) string {
	i := strings.Index(s, sub)
	if i > 0 { // don't modernize since this is a stronger claim than i >= 0
		return s[:i]
	}
	return ""
}

func idx_gtreq_one_invalid(s string, sub string) string {
	i := strings.Index(s, sub)
	if i >= 1 { // don't modernize since this is a stronger claim than i >= 0
		return s[:i]
	}
	return ""
}

func idx_gtr_negone(s string, sub string) string {
	before, _, ok := strings.Cut(s, sub) // want "strings.Index can be simplified using strings.Cut"
	if ok {
		return before
	}
	if ok {
		return s
	}
	return ""
}

// Regression test for a crash (https://go.dev/issue/77208)
func idx_call() {
	i := bytes.Index(b(), []byte(""))
	_ = i
}

// Fix for golang/go#77566
func multipleCallsSameScope(s string) (bool, bool) {
	before, _, ok := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if ok {
		print(before)
	}
	before0, _, ok0 := strings.Cut(s, "-") // want "strings.Index can be simplified using strings.Cut"
	if ok0 {
		print(before0)
	}
	return ok, ok0
}

func shadowing(s string) string {
	ok := "true"
	before := "before"
	print(before)              // declared within scope but not used after the index call, so no fresh name
	before, after, ok0 := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	print(ok)
	if ok0 {
		print(before)
		print(ok0)
		return after
	}
	return ""
}

func foreshadowing(s string) string {
	_, after, ok0 := strings.Cut(s, "=") // want "strings.Index can be simplified using strings.Cut"
	if ok0 {
		return after
	}
	// Generate a fresh name for ok because it is used within the scope after the Index call.
	ok, m := true, "m"
	if ok {
		return m
	}
	if ok0 {
		return s
	}
	return ""
}

func b() []byte {
	return nil
}

func function(s string) {}

func reference_str(s *string) {}

func reference_int(i *int) {}

func blank() {}

// Regression test for unguarded slice uses (https://go.dev/issue/77737).
// The s[colon+1:] usage outside the "if" relies on -1+1=0 to return the full
// string when the separator is absent. Rewriting to "after" would return "".
func unguarded_after_slice(s string) (int, string) {
	colon := strings.Index(s, ":")
	if colon != -1 {
		print(s[:colon])
	}
	return colon, s[colon+1:] // don't modernize: s[colon+1:] not guarded
}

// Same as above but with the guard using i < 0.
func unguarded_after_slice_negcheck(s string) string {
	i := strings.Index(s, ":")
	if i < 0 {
		print("not found")
	}
	return s[i+1:] // don't modernize: s[i+1:] not guarded
}

// Safe: both slice uses are inside the nonneg guard.
func guarded_both_slices(s string) (string, string) {
	before, after, ok := strings.Cut(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if ok {
		return before, after
	}
	return "", s
}

// Safe: slice uses after early-return negative check.
func guarded_early_return(s string) (string, string) {
	before, after, ok := strings.Cut(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if !ok {
		return "", s
	}
	return before, after
}

// Safe: slice uses in else of negative check.
func guarded_neg_else(s string) (string, string) {
	before, after, ok := strings.Cut(s, ":") // want "strings.Index can be simplified using strings.Cut"
	if !ok {
		return "", s
	} else {
		return before, after
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/bytescutprefix/bytescutprefix.go
================================================
package bytescutprefix

import (
	"bytes"
)

func _() {
	if bytes.HasPrefix(bss, bspre) { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := bytes.TrimPrefix(bss, bspre)
		_ = a
	}
	if bytes.HasPrefix([]byte(""), []byte("")) { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := bytes.TrimPrefix([]byte(""), []byte(""))
		_ = a
	}

	if bytes.HasSuffix(bss, bssuf) { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := bytes.TrimSuffix(bss, bssuf)
		_ = a
	}
	if bytes.HasSuffix([]byte(""), []byte("")) { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := bytes.TrimSuffix([]byte(""), []byte(""))
		_ = a
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/bytescutprefix/bytescutprefix.go.golden
================================================
package bytescutprefix

import (
	"bytes"
)

func _() {
	if after, ok := bytes.CutPrefix(bss, bspre); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}
	if after, ok := bytes.CutPrefix([]byte(""), []byte("")); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}

	if before, ok := bytes.CutSuffix(bss, bssuf); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := before
		_ = a
	}
	if before, ok := bytes.CutSuffix([]byte(""), []byte("")); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := before
		_ = a
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/bytescutprefix/bytescutprefix_dot.go
================================================
package bytescutprefix

import (
	. "bytes"
)

var bss, bspre, bssuf []byte

// test supported cases of pattern 1
func _() {
	if HasPrefix(bss, bspre) { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := TrimPrefix(bss, bspre)
		_ = a
	}

	if HasSuffix(bss, bssuf) { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		b := TrimSuffix(bss, bssuf)
		_ = b
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/bytescutprefix/bytescutprefix_dot.go.golden
================================================
package bytescutprefix

import (
	. "bytes"
)

var bss, bspre, bssuf []byte

// test supported cases of pattern 1
func _() {
	if after, ok := CutPrefix(bss, bspre); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}

	if before, ok := CutSuffix(bss, bssuf); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		b := before
		_ = b
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/stringscutprefix.go
================================================
package stringscutprefix

import (
	"strings"
)

var (
	s, pre, suf string
)

// test supported cases of pattern 1 - CutPrefix
func _() {
	if strings.HasPrefix(s, pre) { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := strings.TrimPrefix(s, pre)
		_ = a
	}
	if strings.HasPrefix("", "") { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := strings.TrimPrefix("", "")
		_ = a
	}
	if strings.HasPrefix(s, "") { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		println([]byte(strings.TrimPrefix(s, "")))
	}
	if strings.HasPrefix(s, "") { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b := "", strings.TrimPrefix(s, "")
		_, _ = a, b
	}
	if strings.HasPrefix(s, "") { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b := strings.TrimPrefix(s, ""), strings.TrimPrefix(s, "") // only replace the first occurrence
		s = "123"
		b = strings.TrimPrefix(s, "") // only replace the first occurrence
		_, _ = a, b
	}

	var a, b string
	if strings.HasPrefix(s, "") { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b = "", strings.TrimPrefix(s, "")
		_, _ = a, b
	}
}

// test basic cases for CutSuffix - only covering the key differences
func _() {
	if strings.HasSuffix(s, suf) { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := strings.TrimSuffix(s, suf)
		_ = a
	}
	if strings.HasSuffix(s, "") { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		println([]byte(strings.TrimSuffix(s, "")))
	}
}

// test cases that are not supported by pattern1 - CutPrefix
func _() {
	ok := strings.HasPrefix("", "")
	if ok { // noop, currently it doesn't track the result usage of HasPrefix
		a := strings.TrimPrefix("", "")
		_ = a
	}
	if strings.HasPrefix(s, pre) {
		a := strings.TrimPrefix("", "") // noop, as the argument isn't the same
		_ = a
	}
	if strings.HasPrefix(s, pre) {
		var result string
		result = strings.TrimPrefix("", "") // noop, as we believe define is more popular.
		_ = result
	}
	if strings.HasPrefix("", "") {
		a := strings.TrimPrefix(s, pre) // noop, as the argument isn't the same
		_ = a
	}
	if s1 := s; strings.HasPrefix(s1, pre) {
		a := strings.TrimPrefix(s1, pre) // noop, as IfStmt.Init is present
		_ = a
	}
}

// test basic unsupported case for CutSuffix
func _() {
	if strings.HasSuffix(s, suf) {
		a := strings.TrimSuffix("", "") // noop, as the argument isn't the same
		_ = a
	}
}

var value0 string

// test supported cases of pattern2 - CutPrefix
func _() {
	if after := strings.TrimPrefix(s, pre); after != s { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after := strings.TrimPrefix(s, pre); s != after { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after := strings.TrimPrefix(s, pre); s != after { // want "TrimPrefix can be simplified to CutPrefix"
		println(strings.TrimPrefix(s, pre)) // noop here
	}
	if after := strings.TrimPrefix(s, ""); s != after { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	var ok bool                                          // define an ok variable to test the fix won't shadow it for its if stmt body
	if after := strings.TrimPrefix(s, pre); after != s { // want "TrimPrefix can be simplified to CutPrefix"
		_ = ok
		println(after)
	}
	_ = ok                                               // fine to shadow, since ok is not used within the ifstmt block
	if after := strings.TrimPrefix(s, pre); after != s { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	var predefined string
	if predefined = strings.TrimPrefix(s, pre); s != predefined { // noop
		println(predefined)
	}
	if predefined = strings.TrimPrefix(s, pre); s != predefined { // noop
		println(&predefined)
	}
	var value string
	if value = strings.TrimPrefix(s, pre); s != value { // noop
		println(value)
	}
	lhsMap := make(map[string]string)
	if lhsMap[""] = strings.TrimPrefix(s, pre); s != lhsMap[""] { // noop
		println(lhsMap[""])
	}
	arr := make([]string, 0)
	if arr[0] = strings.TrimPrefix(s, pre); s != arr[0] { // noop
		println(arr[0])
	}
	type example struct {
		field string
	}
	var e example
	if e.field = strings.TrimPrefix(s, pre); s != e.field { // noop
		println(e.field)
	}
}

// test basic cases for pattern2 - CutSuffix
func _() {
	if before := strings.TrimSuffix(s, suf); before != s { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
	if before := strings.TrimSuffix(s, suf); s != before { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
}

// test cases that not supported by pattern2 - CutPrefix
func _() {
	if after := strings.TrimPrefix(s, pre); s != pre { // noop
		println(after)
	}
	if after := strings.TrimPrefix(s, pre); after != pre { // noop
		println(after)
	}
	if strings.TrimPrefix(s, pre) != s {
		println(strings.TrimPrefix(s, pre))
	}
}

// test basic unsupported case for pattern2 - CutSuffix
func _() {
	if before := strings.TrimSuffix(s, suf); s != suf { // noop
		println(before)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/stringscutprefix.go.golden
================================================
package stringscutprefix

import (
	"strings"
)

var (
	s, pre, suf string
)

// test supported cases of pattern 1 - CutPrefix
func _() {
	if after, ok := strings.CutPrefix(s, pre); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}
	if after, ok := strings.CutPrefix("", ""); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}
	if after, ok := strings.CutPrefix(s, ""); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		println([]byte(after))
	}
	if after, ok := strings.CutPrefix(s, ""); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b := "", after
		_, _ = a, b
	}
	if after, ok := strings.CutPrefix(s, ""); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b := after, strings.TrimPrefix(s, "") // only replace the first occurrence
		s = "123"
		b = strings.TrimPrefix(s, "") // only replace the first occurrence
		_, _ = a, b
	}

	var a, b string
	if after, ok := strings.CutPrefix(s, ""); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a, b = "", after
		_, _ = a, b
	}
}

// test basic cases for CutSuffix - only covering the key differences
func _() {
	if before, ok := strings.CutSuffix(s, suf); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := before
		_ = a
	}
	if before, ok := strings.CutSuffix(s, ""); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		println([]byte(before))
	}
}

// test cases that are not supported by pattern1 - CutPrefix
func _() {
	ok := strings.HasPrefix("", "")
	if ok { // noop, currently it doesn't track the result usage of HasPrefix
		a := strings.TrimPrefix("", "")
		_ = a
	}
	if strings.HasPrefix(s, pre) {
		a := strings.TrimPrefix("", "") // noop, as the argument isn't the same
		_ = a
	}
	if strings.HasPrefix(s, pre) {
		var result string
		result = strings.TrimPrefix("", "") // noop, as we believe define is more popular.
		_ = result
	}
	if strings.HasPrefix("", "") {
		a := strings.TrimPrefix(s, pre) // noop, as the argument isn't the same
		_ = a
	}
	if s1 := s; strings.HasPrefix(s1, pre) {
		a := strings.TrimPrefix(s1, pre) // noop, as IfStmt.Init is present
		_ = a
	}
}

// test basic unsupported case for CutSuffix
func _() {
	if strings.HasSuffix(s, suf) {
		a := strings.TrimSuffix("", "") // noop, as the argument isn't the same
		_ = a
	}
}

var value0 string

// test supported cases of pattern2 - CutPrefix
func _() {
	if after, ok := strings.CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after, ok := strings.CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after, ok := strings.CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(strings.TrimPrefix(s, pre)) // noop here
	}
	if after, ok := strings.CutPrefix(s, ""); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	var ok bool // define an ok variable to test the fix won't shadow it for its if stmt body
	if after, ok0 := strings.CutPrefix(s, pre); ok0 { // want "TrimPrefix can be simplified to CutPrefix"
		_ = ok
		println(after)
	}
	_ = ok                                               // fine to shadow, since ok is not used within the ifstmt block
	if after, ok := strings.CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	var predefined string
	if predefined = strings.TrimPrefix(s, pre); s != predefined { // noop
		println(predefined)
	}
	if predefined = strings.TrimPrefix(s, pre); s != predefined { // noop
		println(&predefined)
	}
	var value string
	if value = strings.TrimPrefix(s, pre); s != value { // noop
		println(value)
	}
	lhsMap := make(map[string]string)
	if lhsMap[""] = strings.TrimPrefix(s, pre); s != lhsMap[""] { // noop
		println(lhsMap[""])
	}
	arr := make([]string, 0)
	if arr[0] = strings.TrimPrefix(s, pre); s != arr[0] { // noop
		println(arr[0])
	}
	type example struct {
		field string
	}
	var e example
	if e.field = strings.TrimPrefix(s, pre); s != e.field { // noop
		println(e.field)
	}
}

// test basic cases for pattern2 - CutSuffix
func _() {
	if before, ok := strings.CutSuffix(s, suf); ok { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
	if before, ok := strings.CutSuffix(s, suf); ok { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
}

// test cases that not supported by pattern2 - CutPrefix
func _() {
	if after := strings.TrimPrefix(s, pre); s != pre { // noop
		println(after)
	}
	if after := strings.TrimPrefix(s, pre); after != pre { // noop
		println(after)
	}
	if strings.TrimPrefix(s, pre) != s {
		println(strings.TrimPrefix(s, pre))
	}
}

// test basic unsupported case for pattern2 - CutSuffix
func _() {
	if before := strings.TrimSuffix(s, suf); s != suf { // noop
		println(before)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/stringscutprefix_dot.go
================================================
package stringscutprefix

import (
	. "strings"
)

// test supported cases of pattern 1 - CutPrefix
func _() {
	if HasPrefix(s, pre) { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := TrimPrefix(s, pre)
		_ = a
	}
}

// test supported cases of pattern 1 - CutSuffix
func _() {
	if HasSuffix(s, suf) { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := TrimSuffix(s, suf)
		_ = a
	}
}

// test supported cases of pattern2 - CutPrefix
func _() {
	if after := TrimPrefix(s, pre); after != s { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after := TrimPrefix(s, pre); s != after { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
}

// test supported cases of pattern2 - CutSuffix
func _() {
	if before := TrimSuffix(s, suf); before != s { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
	if before := TrimSuffix(s, suf); s != before { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/stringscutprefix/stringscutprefix_dot.go.golden
================================================
package stringscutprefix

import (
	. "strings"
)

// test supported cases of pattern 1 - CutPrefix
func _() {
	if after, ok := CutPrefix(s, pre); ok { // want "HasPrefix \\+ TrimPrefix can be simplified to CutPrefix"
		a := after
		_ = a
	}
}

// test supported cases of pattern 1 - CutSuffix
func _() {
	if before, ok := CutSuffix(s, suf); ok { // want "HasSuffix \\+ TrimSuffix can be simplified to CutSuffix"
		a := before
		_ = a
	}
}

// test supported cases of pattern2 - CutPrefix
func _() {
	if after, ok := CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
	if after, ok := CutPrefix(s, pre); ok { // want "TrimPrefix can be simplified to CutPrefix"
		println(after)
	}
}

// test supported cases of pattern2 - CutSuffix
func _() {
	if before, ok := CutSuffix(s, suf); ok { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
	if before, ok := CutSuffix(s, suf); ok { // want "TrimSuffix can be simplified to CutSuffix"
		println(before)
	}
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/testingcontext/testingcontext.go
================================================
package testingcontext


================================================
FILE: go/analysis/passes/modernize/testdata/src/testingcontext/testingcontext_test.go
================================================
package testingcontext

import (
	"context"

	"testing"
)

func Test(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using t.Context"
	defer cancel()
	_ = ctx

	func() {
		ctx, cancel := context.WithCancel(context.Background()) // Nope. scope of defer is not the testing func.
		defer cancel()
		_ = ctx
	}()

	{
		ctx, cancel := context.WithCancel(context.TODO()) // want "context.WithCancel can be modernized using t.Context"
		defer cancel()
		_ = ctx
		var t int // not in scope of the call to WithCancel
		_ = t
	}

	{
		ctx := context.Background()
		ctx, cancel := context.WithCancel(context.Background()) // Nope. ctx is redeclared.
		defer cancel()
		_ = ctx
	}

	{
		var t int
		ctx, cancel := context.WithCancel(context.Background()) // Nope. t is shadowed.
		defer cancel()
		_ = ctx
		_ = t
	}

	t.Run("subtest", func(t2 *testing.T) {
		ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using t2.Context"
		defer cancel()
		_ = ctx
	})
}

func TestAlt(t2 *testing.T) {
	ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using t2.Context"
	defer cancel()
	_ = ctx
}

func Testnot(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background()) // Nope. Not a test func.
	defer cancel()
	_ = ctx
}

func Benchmark(b *testing.B) {
	ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using b.Context"
	defer cancel()
	_ = ctx

	b.Run("subtest", func(b2 *testing.B) {
		ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using b2.Context"
		defer cancel()
		_ = ctx
	})
}

func Fuzz(f *testing.F) {
	ctx, cancel := context.WithCancel(context.Background()) // want "context.WithCancel can be modernized using f.Context"
	defer cancel()
	_ = ctx
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/testingcontext/testingcontext_test.go.golden
================================================
package testingcontext

import (
	"context"

	"testing"
)

func Test(t *testing.T) {
	ctx := t.Context()
	_ = ctx

	func() {
		ctx, cancel := context.WithCancel(context.Background()) // Nope. scope of defer is not the testing func.
		defer cancel()
		_ = ctx
	}()

	{
		ctx := t.Context()
		_ = ctx
		var t int // not in scope of the call to WithCancel
		_ = t
	}

	{
		ctx := context.Background()
		ctx, cancel := context.WithCancel(context.Background()) // Nope. ctx is redeclared.
		defer cancel()
		_ = ctx
	}

	{
		var t int
		ctx, cancel := context.WithCancel(context.Background()) // Nope. t is shadowed.
		defer cancel()
		_ = ctx
		_ = t
	}

	t.Run("subtest", func(t2 *testing.T) {
		ctx := t2.Context()
		_ = ctx
	})
}

func TestAlt(t2 *testing.T) {
	ctx := t2.Context()
	_ = ctx
}

func Testnot(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background()) // Nope. Not a test func.
	defer cancel()
	_ = ctx
}

func Benchmark(b *testing.B) {
	ctx := b.Context()
	_ = ctx

	b.Run("subtest", func(b2 *testing.B) {
		ctx := b2.Context()
		_ = ctx
	})
}

func Fuzz(f *testing.F) {
	ctx := f.Context()
	_ = ctx
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/unsafefuncs/unsafefuncs.go
================================================
package unsafefuncs

import "unsafe"

func _(ptr unsafe.Pointer) unsafe.Pointer {
	return unsafe.Pointer(uintptr(ptr) + 1) // want `pointer \+ integer can be simplified using unsafe.Add`
}

type uP = unsafe.Pointer

func _(ptr uP) uP {
	return uP(uintptr(ptr) + 1) // want `pointer \+ integer can be simplified using unsafe.Add`
}

func _(ptr unsafe.Pointer, n int) unsafe.Pointer {
	return unsafe.Pointer(uintptr(ptr) + uintptr(n)) // want `pointer \+ integer can be simplified using unsafe.Add`
}

func _(ptr *byte, len int) *byte {
	return (*byte)(unsafe.Pointer(uintptr(unsafe.Pointer(ptr)) + uintptr(len))) // want `pointer \+ integer can be simplified using unsafe.Add`
}

type namedUP unsafe.Pointer

func _(ptr namedUP) namedUP {
	return namedUP(uintptr(ptr) + 1) // nope: Add does not accept named unsafe.Pointer types
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/unsafefuncs/unsafefuncs.go.golden
================================================
package unsafefuncs

import "unsafe"

func _(ptr unsafe.Pointer) unsafe.Pointer {
	return unsafe.Add(ptr, 1) // want `pointer \+ integer can be simplified using unsafe.Add`
}

type uP = unsafe.Pointer

func _(ptr uP) uP {
	return unsafe.Add(ptr, 1) // want `pointer \+ integer can be simplified using unsafe.Add`
}

func _(ptr unsafe.Pointer, n int) unsafe.Pointer {
	return unsafe.Add(ptr, n) // want `pointer \+ integer can be simplified using unsafe.Add`
}

func _(ptr *byte, len int) *byte {
	return (*byte)(unsafe.Add(unsafe.Pointer(ptr), len)) // want `pointer \+ integer can be simplified using unsafe.Add`
}

type namedUP unsafe.Pointer

func _(ptr namedUP) namedUP {
	return namedUP(uintptr(ptr) + 1) // nope: Add does not accept named unsafe.Pointer types
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup.go
================================================
package waitgroup

import (
	"fmt"
	"sync"
)

// supported case for pattern 1.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
	}()

	for range 10 {
		wg.Add(1)
		go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
			defer wg.Done()
			fmt.Println()
		}()
	}
}

// supported case for pattern 2.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		wg.Done()
	}()

	for range 10 {
		wg.Add(1)
		go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
			fmt.Println()
			wg.Done()
		}()
	}
}

// this function puts some wrong usages but waitgroupgo modernizer will still offer fixes.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		fmt.Println()
		wg.Done()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
		wg.Done()
	}()
}

// this function puts the unsupported cases of pattern 1.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {}()

	wg.Add(1)
	go func(i int) {
		defer wg.Done()
		fmt.Println(i)
	}(1)

	wg.Add(1)
	go func() {
		fmt.Println()
		defer wg.Done()
	}()

	wg.Add(1)
	go func() { // noop: no wg.Done call inside function body.
		fmt.Println()
	}()

	go func() { // noop: no Add call before this go stmt.
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(2) // noop: only support Add(1).
	go func() {
		defer wg.Done()
	}()

	var wg1 sync.WaitGroup
	wg1.Add(1) // noop: Add and Done should be the same object.
	go func() {
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1) // noop: Add and Done should be the same object.
	go func() {
		defer wg1.Done()
		fmt.Println()
	}()

	wg.Add(1) // noop: function literal has return values, wg.Go requires func().
	go func() int {
		defer wg.Done()
		return 0
	}()
}

// this function puts the unsupported cases of pattern 2.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		wg.Done()
		fmt.Println()
	}()

	go func() { // noop: no Add call before this go stmt.
		fmt.Println()
		wg.Done()
	}()

	var wg1 sync.WaitGroup
	wg1.Add(1) // noop: Add and Done should be the same object.
	go func() {
		fmt.Println()
		wg.Done()
	}()

	wg.Add(1) // noop: Add and Done should be the same object.
	go func() {
		fmt.Println()
		wg1.Done()
	}()

	wg.Add(1) // noop: function literal has return values, wg.Go requires func().
	go func() int {
		fmt.Println()
		wg.Done()
		return 0
	}()
}

type Server struct {
	wg sync.WaitGroup
}

type ServerContainer struct {
	serv Server
}

func _() {
	var s Server
	s.wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
		s.wg.Done()
	}()

	var sc ServerContainer
	sc.serv.wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
		sc.serv.wg.Done()
	}()

	var wg sync.WaitGroup
	arr := [1]*sync.WaitGroup{&wg}
	arr[0].Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
		arr[0].Done()
	}()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup.go.golden
================================================
package waitgroup

import (
	"fmt"
	"sync"
)

// supported case for pattern 1.
func _() {
	var wg sync.WaitGroup
	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
	})

	for range 10 {
		wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
			fmt.Println()
		})
	}
}

// supported case for pattern 2.
func _() {
	var wg sync.WaitGroup
	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
	})

	for range 10 {
		wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
			fmt.Println()
		})
	}
}

// this function puts some wrong usages but waitgroupgo modernizer will still offer fixes.
func _() {
	var wg sync.WaitGroup
	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		fmt.Println()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
	})
}

// this function puts the unsupported cases of pattern 1.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {}()

	wg.Add(1)
	go func(i int) {
		defer wg.Done()
		fmt.Println(i)
	}(1)

	wg.Add(1)
	go func() {
		fmt.Println()
		defer wg.Done()
	}()

	wg.Add(1)
	go func() { // noop: no wg.Done call inside function body.
		fmt.Println()
	}()

	go func() { // noop: no Add call before this go stmt.
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(2) // noop: only support Add(1).
	go func() {
		defer wg.Done()
	}()

	var wg1 sync.WaitGroup
	wg1.Add(1) // noop: Add and Done should be the same object.
	go func() {
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1) // noop: Add and Done should be the same object.
	go func() {
		defer wg1.Done()
		fmt.Println()
	}()

	wg.Add(1) // noop: function literal has return values, wg.Go requires func().
	go func() int {
		defer wg.Done()
		return 0
	}()
}

// this function puts the unsupported cases of pattern 2.
func _() {
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		wg.Done()
		fmt.Println()
	}()

	go func() { // noop: no Add call before this go stmt.
		fmt.Println()
		wg.Done()
	}()

	var wg1 sync.WaitGroup
	wg1.Add(1) // noop: Add and Done should be the same object.
	go func() {
		fmt.Println()
		wg.Done()
	}()

	wg.Add(1) // noop: Add and Done should be the same object.
	go func() {
		fmt.Println()
		wg1.Done()
	}()

	wg.Add(1) // noop: function literal has return values, wg.Go requires func().
	go func() int {
		fmt.Println()
		wg.Done()
		return 0
	}()
}

type Server struct {
	wg sync.WaitGroup
}

type ServerContainer struct {
	serv Server
}

func _() {
	var s Server
	s.wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
	})

	var sc ServerContainer
	sc.serv.wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
	})

	var wg sync.WaitGroup
	arr := [1]*sync.WaitGroup{&wg}
	arr[0].Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		print()
	})
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup_alias.go
================================================
package waitgroup

import (
	"fmt"
	sync1 "sync"
)

func _() {
	var wg sync1.WaitGroup
	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
	}()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup_alias.go.golden
================================================
package waitgroup

import (
	"fmt"
	sync1 "sync"
)

func _() {
	var wg sync1.WaitGroup
	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})
}

================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup_dot.go
================================================
package waitgroup

import (
	"fmt"
	. "sync"
)

// supported case for pattern 1.
func _() {
	var wg WaitGroup
	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		defer wg.Done()
		fmt.Println()
	}()

	wg.Add(1)
	go func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
		wg.Done()
	}()
}


================================================
FILE: go/analysis/passes/modernize/testdata/src/waitgroupgo/waitgroup_dot.go.golden
================================================
package waitgroup

import (
	"fmt"
	. "sync"
)

// supported case for pattern 1.
func _() {
	var wg WaitGroup
	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})

	wg.Go(func() { // want "Goroutine creation can be simplified using WaitGroup.Go"
		fmt.Println()
	})
}

================================================
FILE: go/analysis/passes/modernize/testingcontext.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var TestingContextAnalyzer = &analysis.Analyzer{
	Name: "testingcontext",
	Doc:  analyzerutil.MustExtractDoc(doc, "testingcontext"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: testingContext,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#testingcontext",
}

// The testingContext pass replaces calls to context.WithCancel from within
// tests to a use of testing.{T,B,F}.Context(), added in Go 1.24.
//
// Specifically, the testingContext pass suggests to replace:
//
//	ctx, cancel := context.WithCancel(context.Background()) // or context.TODO
//	defer cancel()
//
// with:
//
//	ctx := t.Context()
//
// provided:
//
//   - ctx and cancel are declared by the assignment
//   - the deferred call is the only use of cancel
//   - the call is within a test or subtest function
//   - the relevant testing.{T,B,F} is named and not shadowed at the call
func testingContext(pass *analysis.Pass) (any, error) {
	var (
		index = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info  = pass.TypesInfo

		contextWithCancel = index.Object("context", "WithCancel")
	)

calls:
	for cur := range index.Calls(contextWithCancel) {
		call := cur.Node().(*ast.CallExpr)
		// Have: context.WithCancel(...)

		arg, ok := call.Args[0].(*ast.CallExpr)
		if !ok {
			continue
		}
		if !typesinternal.IsFunctionNamed(typeutil.Callee(info, arg), "context", "Background", "TODO") {
			continue
		}
		// Have: context.WithCancel(context.{Background,TODO}())

		parent := cur.Parent()
		assign, ok := parent.Node().(*ast.AssignStmt)
		if !ok || assign.Tok != token.DEFINE {
			continue
		}
		// Have: a, b := context.WithCancel(context.{Background,TODO}())

		// Check that both a and b are declared, not redeclarations.
		var lhs []types.Object
		for _, expr := range assign.Lhs {
			id, ok := expr.(*ast.Ident)
			if !ok {
				continue calls
			}
			obj, ok := info.Defs[id]
			if !ok {
				continue calls
			}
			lhs = append(lhs, obj)
		}

		next, ok := parent.NextSibling()
		if !ok {
			continue
		}
		defr, ok := next.Node().(*ast.DeferStmt)
		if !ok {
			continue
		}
		deferId, ok := defr.Call.Fun.(*ast.Ident)
		if !ok || !soleUseIs(index, lhs[1], deferId) {
			continue // b is used elsewhere
		}
		// Have:
		// a, b := context.WithCancel(context.{Background,TODO}())
		// defer b()

		// Check that we are in a test func.
		var testObj types.Object // relevant testing.{T,B,F}, or nil
		if curFunc, ok := enclosingFunc(cur); ok {
			switch n := curFunc.Node().(type) {
			case *ast.FuncLit:
				if ek, idx := curFunc.ParentEdge(); ek == edge.CallExpr_Args && idx == 1 {
					// Have: call(..., func(...) { ...context.WithCancel(...)... })
					obj := typeutil.Callee(info, curFunc.Parent().Node().(*ast.CallExpr))
					if (typesinternal.IsMethodNamed(obj, "testing", "T", "Run") ||
						typesinternal.IsMethodNamed(obj, "testing", "B", "Run")) &&
						len(n.Type.Params.List[0].Names) == 1 {

						// Have tb.Run(..., func(..., tb *testing.[TB]) { ...context.WithCancel(...)... }
						testObj = info.Defs[n.Type.Params.List[0].Names[0]]
					}
				}

			case *ast.FuncDecl:
				testObj = isTestFn(info, n)
			}
		}
		if testObj != nil && analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(cur), versions.Go1_24) {
			// Have a test function. Check that we can resolve the relevant
			// testing.{T,B,F} at the current position.
			if _, obj := lhs[0].Parent().LookupParent(testObj.Name(), lhs[0].Pos()); obj == testObj {
				pass.Report(analysis.Diagnostic{
					Pos:     call.Fun.Pos(),
					End:     call.Fun.End(),
					Message: fmt.Sprintf("context.WithCancel can be modernized using %s.Context", testObj.Name()),
					SuggestedFixes: []analysis.SuggestedFix{{
						Message: fmt.Sprintf("Replace context.WithCancel with %s.Context", testObj.Name()),
						TextEdits: []analysis.TextEdit{{
							Pos:     assign.Pos(),
							End:     defr.End(),
							NewText: fmt.Appendf(nil, "%s := %s.Context()", lhs[0].Name(), testObj.Name()),
						}},
					}},
				})
			}
		}
	}
	return nil, nil
}

// soleUseIs reports whether id is the sole Ident that uses obj.
// (It returns false if there were no uses of obj.)
func soleUseIs(index *typeindex.Index, obj types.Object, id *ast.Ident) bool {
	empty := true
	for use := range index.Uses(obj) {
		empty = false
		if use.Node() != id {
			return false
		}
	}
	return !empty
}

// isTestFn checks whether fn is a test function (TestX, BenchmarkX, FuzzX),
// returning the corresponding types.Object of the *testing.{T,B,F} argument.
// Returns nil if fn is a test function, but the testing.{T,B,F} argument is
// unnamed (or _).
//
// TODO(rfindley): consider handling the case of an unnamed argument, by adding
// an edit to give the argument a name.
//
// Adapted from go/analysis/passes/tests.
// TODO(rfindley): consider refactoring to share logic.
func isTestFn(info *types.Info, fn *ast.FuncDecl) types.Object {
	// Want functions with 0 results and 1 parameter.
	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
		fn.Type.Params == nil ||
		len(fn.Type.Params.List) != 1 ||
		len(fn.Type.Params.List[0].Names) != 1 {

		return nil
	}

	prefix := testKind(fn.Name.Name)
	if prefix == "" {
		return nil
	}

	if tparams := fn.Type.TypeParams; tparams != nil && len(tparams.List) > 0 {
		return nil // test functions must not be generic
	}

	obj := info.Defs[fn.Type.Params.List[0].Names[0]]
	if obj == nil {
		return nil // e.g. _ *testing.T
	}

	var name string
	switch prefix {
	case "Test":
		name = "T"
	case "Benchmark":
		name = "B"
	case "Fuzz":
		name = "F"
	}

	if !typesinternal.IsPointerToNamed(obj.Type(), "testing", name) {
		return nil
	}
	return obj
}

// testKind returns "Test", "Benchmark", or "Fuzz" if name is a valid resp.
// test, benchmark, or fuzz function name. Otherwise, isTestName returns "".
//
// Adapted from go/analysis/passes/tests.isTestName.
func testKind(name string) string {
	var prefix string
	switch {
	case strings.HasPrefix(name, "Test"):
		prefix = "Test"
	case strings.HasPrefix(name, "Benchmark"):
		prefix = "Benchmark"
	case strings.HasPrefix(name, "Fuzz"):
		prefix = "Fuzz"
	}
	if prefix == "" {
		return ""
	}
	suffix := name[len(prefix):]
	if len(suffix) == 0 {
		// "Test" is ok.
		return prefix
	}
	r, _ := utf8.DecodeRuneInString(suffix)
	if unicode.IsLower(r) {
		return ""
	}
	return prefix
}


================================================
FILE: go/analysis/passes/modernize/unsafefuncs.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/goplsexport"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

// TODO(adonovan): also support:
//
// func String(ptr *byte, len IntegerType) string
// func StringData(str string) *byte
// func Slice(ptr *ArbitraryType, len IntegerType) []ArbitraryType
// func SliceData(slice []ArbitraryType) *ArbitraryType

var unsafeFuncsAnalyzer = &analysis.Analyzer{
	Name:     "unsafefuncs",
	Doc:      analyzerutil.MustExtractDoc(doc, "unsafefuncs"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      unsafefuncs,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#unsafefuncs",
}

func init() {
	// Export to gopls until this is a published modernizer.
	goplsexport.UnsafeFuncsModernizer = unsafeFuncsAnalyzer
}

func unsafefuncs(pass *analysis.Pass) (any, error) {
	// Short circuit if the package doesn't use unsafe.
	// (In theory one could use some imported alias of unsafe.Pointer,
	// but let's ignore that.)
	if !typesinternal.Imports(pass.Pkg, "unsafe") {
		return nil, nil
	}

	var (
		inspect        = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info           = pass.TypesInfo
		tUnsafePointer = types.Typ[types.UnsafePointer]
	)

	// isConversion reports whether e is a conversion T(x).
	// If so, it returns T and x.
	isConversion := func(curExpr inspector.Cursor) (t types.Type, x inspector.Cursor) {
		e := curExpr.Node().(ast.Expr)
		if conv, ok := ast.Unparen(e).(*ast.CallExpr); ok && len(conv.Args) == 1 {
			if tv := pass.TypesInfo.Types[conv.Fun]; tv.IsType() {
				return tv.Type, curExpr.ChildAt(edge.CallExpr_Args, 0)
			}
		}
		return
	}

	// The general form is where ptr and the result are of type unsafe.Pointer:
	//
	// 	unsafe.Pointer(uintptr(ptr) + uintptr(n))
	// =>
	// 	unsafe.Add(ptr, n)

	// Search for 'unsafe.Pointer(uintptr + uintptr)'
	// where the left operand was converted from a pointer.
	//
	// (Start from sum, not conversion, as it is not
	// uncommon to use a local type alias for unsafe.Pointer.)
	for curSum := range inspect.Root().Preorder((*ast.BinaryExpr)(nil)) {
		if sum, ok := curSum.Node().(*ast.BinaryExpr); ok &&
			sum.Op == token.ADD &&
			types.Identical(info.TypeOf(sum.X), types.Typ[types.Uintptr]) &&
			curSum.ParentEdgeKind() == edge.CallExpr_Args {
			// Have: sum ≡ T(x:...uintptr... + y:...uintptr...)
			curX := curSum.ChildAt(edge.BinaryExpr_X, -1)
			curY := curSum.ChildAt(edge.BinaryExpr_Y, -1)

			// Is sum converted to unsafe.Pointer?
			curResult := curSum.Parent()
			if t, _ := isConversion(curResult); !(t != nil && types.Identical(t, tUnsafePointer)) {
				continue
			}
			// Have: result ≡ unsafe.Pointer(x:...uintptr... + y:...uintptr...)

			// Is sum.x converted from unsafe.Pointer?
			_, curPtr := isConversion(curX)
			if !curPtr.Valid() {
				continue
			}
			ptr := curPtr.Node().(ast.Expr)
			if !types.Identical(info.TypeOf(ptr), tUnsafePointer) {
				continue
			}
			// Have: result ≡ unsafe.Pointer(x:uintptr(...unsafe.Pointer...) + y:...uintptr...)

			file := astutil.EnclosingFile(curSum)
			if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_17) {
				continue // unsafe.Add not available in this file
			}

			// import "unsafe"
			unsafedot, edits := refactor.AddImport(info, file, "unsafe", "unsafe", "Add", sum.Pos())

			// unsafe.Pointer(x + y)
			// ---------------     -
			//                x + y
			edits = append(edits, deleteConv(curResult)...)

			// uintptr   (ptr) + offset
			// -----------   ----      -
			// unsafe.Add(ptr,   offset)
			edits = append(edits, []analysis.TextEdit{
				{
					Pos:     sum.Pos(),
					End:     ptr.Pos(),
					NewText: fmt.Appendf(nil, "%sAdd(", unsafedot),
				},
				{
					Pos:     ptr.End(),
					End:     sum.Y.Pos(),
					NewText: []byte(", "),
				},
				{
					Pos:     sum.Y.End(),
					End:     sum.Y.End(),
					NewText: []byte(")"),
				},
			}...)

			// Variant: sum.y operand was converted from another integer type.
			// Discard the conversion, as Add is generic over integers.
			//
			// e.g. unsafe.Pointer(uintptr(ptr) + uintptr(len(s)))
			//                                    --------      -
			//      unsafe.Add    (        ptr,           len(s))
			if t, _ := isConversion(curY); t != nil && isInteger(t) {
				edits = append(edits, deleteConv(curY)...)
			}

			pass.Report(analysis.Diagnostic{
				Pos:     sum.Pos(),
				End:     sum.End(),
				Message: "pointer + integer can be simplified using unsafe.Add",
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   "Simplify pointer addition using unsafe.Add",
					TextEdits: edits,
				}},
			})
		}
	}

	return nil, nil
}

// deleteConv returns edits for changing T(x) to x, respecting precedence.
func deleteConv(cur inspector.Cursor) []analysis.TextEdit {
	conv := cur.Node().(*ast.CallExpr)

	usesPrec := func(n ast.Node) bool {
		switch n.(type) {
		case *ast.BinaryExpr, *ast.UnaryExpr:
			return true
		}
		return false
	}

	// Be careful not to change precedence of e.g. T(1+2) * 3.
	// TODO(adonovan): refine this.
	if usesPrec(cur.Parent().Node()) && usesPrec(conv.Args[0]) {
		// T(x+y) * z
		// -
		//  (x+y) * z
		return []analysis.TextEdit{{
			Pos: conv.Fun.Pos(),
			End: conv.Fun.End(),
		}}
	}

	// T(x)
	// -- -
	//   x
	return []analysis.TextEdit{
		{
			Pos: conv.Pos(),
			End: conv.Args[0].Pos(),
		},
		{
			Pos: conv.Args[0].End(),
			End: conv.End(),
		},
	}
}

func isInteger(t types.Type) bool {
	basic, ok := t.Underlying().(*types.Basic)
	return ok && basic.Info()&types.IsInteger != 0
}


================================================
FILE: go/analysis/passes/modernize/waitgroupgo.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modernize

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/printer"
	"slices"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

var WaitGroupGoAnalyzer = &analysis.Analyzer{
	Name: "waitgroupgo",
	Doc:  analyzerutil.MustExtractDoc(doc, "waitgroupgo"),
	Requires: []*analysis.Analyzer{
		inspect.Analyzer,
		typeindexanalyzer.Analyzer,
	},
	Run: waitgroup,
	URL: "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#waitgroupgo",
}

// The waitgroupgo pass replaces old more complex code with
// go1.25 added API WaitGroup.Go.
//
// Patterns:
//
//  1. wg.Add(1); go func() { defer wg.Done(); ... }()
//     =>
//     wg.Go(go func() { ... })
//
//  2. wg.Add(1); go func() { ...; wg.Done() }()
//     =>
//     wg.Go(go func() { ... })
//
// The wg.Done must occur within the first statement of the block in a
// defer format or last statement of the block, and the offered fix
// only removes the first/last wg.Done call. It doesn't fix existing
// wrong usage of sync.WaitGroup.
//
// The use of WaitGroup.Go in pattern 1 implicitly introduces a
// 'defer', which may change the behavior in the case of panic from
// the "..." logic. In this instance, the change is safe: before and
// after the transformation, an unhandled panic inevitably results in
// a fatal crash. The fact that the transformed code calls wg.Done()
// before the crash doesn't materially change anything. (If Done had
// other effects, or blocked, or if WaitGroup.Go propagated panics
// from child to parent goroutine, the argument would be different.)
func waitgroup(pass *analysis.Pass) (any, error) {
	var (
		index             = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info              = pass.TypesInfo
		syncWaitGroupAdd  = index.Selection("sync", "WaitGroup", "Add")
		syncWaitGroupDone = index.Selection("sync", "WaitGroup", "Done")
	)
	if !index.Used(syncWaitGroupDone) {
		return nil, nil
	}

	for curAddCall := range index.Calls(syncWaitGroupAdd) {
		// Extract receiver from wg.Add call.
		addCall := curAddCall.Node().(*ast.CallExpr)
		if !isIntLiteral(info, addCall.Args[0], 1) {
			continue // not a call to wg.Add(1)
		}
		// Inv: the Args[0] check ensures addCall is not of
		// the form sync.WaitGroup.Add(&wg, 1).
		addCallRecv := ast.Unparen(addCall.Fun).(*ast.SelectorExpr).X

		// Following statement must be go func() { ... } ().
		curAddStmt := curAddCall.Parent()
		if !is[*ast.ExprStmt](curAddStmt.Node()) {
			continue // unnecessary parens?
		}
		curNext, ok := curAddCall.Parent().NextSibling()
		if !ok {
			continue // no successor
		}
		goStmt, ok := curNext.Node().(*ast.GoStmt)
		if !ok {
			continue // not a go stmt
		}
		lit, ok := goStmt.Call.Fun.(*ast.FuncLit)
		if !ok || len(goStmt.Call.Args) != 0 {
			continue // go argument is not func(){...}()
		}
		if lit.Type.Results != nil && len(lit.Type.Results.List) > 0 {
			continue // function literal has return values; wg.Go requires func()
		}
		list := lit.Body.List
		if len(list) == 0 {
			continue
		}

		// Body must start with "defer wg.Done()" or end with "wg.Done()".
		var doneStmt ast.Stmt
		if deferStmt, ok := list[0].(*ast.DeferStmt); ok &&
			typeutil.Callee(info, deferStmt.Call) == syncWaitGroupDone &&
			astutil.EqualSyntax(ast.Unparen(deferStmt.Call.Fun).(*ast.SelectorExpr).X, addCallRecv) {
			doneStmt = deferStmt // "defer wg.Done()"

		} else if lastStmt, ok := list[len(list)-1].(*ast.ExprStmt); ok {
			if doneCall, ok := lastStmt.X.(*ast.CallExpr); ok &&
				typeutil.Callee(info, doneCall) == syncWaitGroupDone &&
				astutil.EqualSyntax(ast.Unparen(doneCall.Fun).(*ast.SelectorExpr).X, addCallRecv) {
				doneStmt = lastStmt // "wg.Done()"
			}
		}
		if doneStmt == nil {
			continue
		}
		curDoneStmt, ok := curNext.FindNode(doneStmt)
		if !ok {
			panic("can't find Cursor for 'done' statement")
		}

		file := astutil.EnclosingFile(curAddCall)
		if !analyzerutil.FileUsesGoVersion(pass, file, versions.Go1_25) {
			continue
		}
		tokFile := pass.Fset.File(file.Pos())

		var addCallRecvText bytes.Buffer
		err := printer.Fprint(&addCallRecvText, pass.Fset, addCallRecv)
		if err != nil {
			continue // error getting text for the edit
		}

		pass.Report(analysis.Diagnostic{
			// go func() {
			// ~~~~~~~~~
			Pos:     goStmt.Pos(),
			End:     lit.Type.End(),
			Message: "Goroutine creation can be simplified using WaitGroup.Go",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Simplify by using WaitGroup.Go",
				TextEdits: slices.Concat(
					// delete "wg.Add(1)"
					refactor.DeleteStmt(tokFile, curAddStmt),
					// delete "wg.Done()" or "defer wg.Done()"
					refactor.DeleteStmt(tokFile, curDoneStmt),
					[]analysis.TextEdit{
						// go    func()
						// ------
						// wg.Go(func()
						{
							Pos:     goStmt.Pos(),
							End:     goStmt.Call.Pos(),
							NewText: fmt.Appendf(nil, "%s.Go(", addCallRecvText.String()),
						},
						// ... }()
						//      -
						// ... } )
						{
							Pos: goStmt.Call.Lparen,
							End: goStmt.Call.Rparen,
						},
					},
				),
			}},
		})
	}
	return nil, nil
}


================================================
FILE: go/analysis/passes/nilfunc/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nilfunc defines an Analyzer that checks for useless
// comparisons against nil.
//
// # Analyzer nilfunc
//
// nilfunc: check for useless comparisons between functions and nil
//
// A useless comparison is one like f == nil as opposed to f() == nil.
package nilfunc


================================================
FILE: go/analysis/passes/nilfunc/nilfunc.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nilfunc defines an Analyzer that checks for useless
// comparisons against nil.
package nilfunc

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "nilfunc",
	Doc:      analyzerutil.MustExtractDoc(doc, "nilfunc"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilfunc",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.BinaryExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		e := n.(*ast.BinaryExpr)

		// Only want == or != comparisons.
		if e.Op != token.EQL && e.Op != token.NEQ {
			return
		}

		// Only want comparisons with a nil identifier on one side.
		var e2 ast.Expr
		switch {
		case pass.TypesInfo.Types[e.X].IsNil():
			e2 = e.Y
		case pass.TypesInfo.Types[e.Y].IsNil():
			e2 = e.X
		default:
			return
		}

		// Only want functions.
		obj := pass.TypesInfo.Uses[typesinternal.UsedIdent(pass.TypesInfo, e2)]
		if _, ok := obj.(*types.Func); !ok {
			return
		}

		pass.ReportRangef(e, "comparison of function %v %v nil is always %v", obj.Name(), e.Op, e.Op == token.NEQ)
	})
	return nil, nil
}


================================================
FILE: go/analysis/passes/nilfunc/nilfunc_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nilfunc_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/nilfunc"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, nilfunc.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/nilfunc/testdata/src/a/a.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

func F() {}

type T struct {
	F func()
}

func (T) M() {}

var Fv = F

func Comparison() {
	var t T
	var fn func()
	if fn == nil || Fv == nil || t.F == nil {
		// no error; these func vars or fields may be nil
	}
	if F == nil { // want "comparison of function F == nil is always false"
		panic("can't happen")
	}
	if t.M == nil { // want "comparison of function M == nil is always false"
		panic("can't happen")
	}
	if F != nil { // want "comparison of function F != nil is always true"
		if t.M != nil { // want "comparison of function M != nil is always true"
			return
		}
	}
	panic("can't happen")
}


================================================
FILE: go/analysis/passes/nilfunc/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the lostcancel checker.

package typeparams

func f[P any]() {}

func g[P1 any, P2 any](x P1) {}

var f1 = f[int]

type T1[P any] struct {
	f func() P
}

type T2[P1 any, P2 any] struct {
	g func(P1) P2
}

func Comparison[P any](f2 func() T1[P]) {
	var t1 T1[P]
	var t2 T2[P, int]
	var fn func()
	if fn == nil || f1 == nil || f2 == nil || t1.f == nil || t2.g == nil {
		// no error; these func vars or fields may be nil
	}
	if f[P] == nil { // want "comparison of function f == nil is always false"
		panic("can't happen")
	}
	if f[int] == nil { // want "comparison of function f == nil is always false"
		panic("can't happen")
	}
	if g[P, int] == nil { // want "comparison of function g == nil is always false"
		panic("can't happen")
	}
}

func Index[P any](a [](func() P)) {
	if a[1] == nil {
		// no error
	}
	var t1 []T1[P]
	var t2 [][]T2[P, P]
	if t1[1].f == nil || t2[0][1].g == nil {
		// no error
	}
}


================================================
FILE: go/analysis/passes/nilness/cmd/nilness/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The nilness command applies the golang.org/x/tools/go/analysis/passes/nilness
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/nilness"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(nilness.Analyzer) }


================================================
FILE: go/analysis/passes/nilness/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nilness inspects the control-flow graph of an SSA function
// and reports errors such as nil pointer dereferences and degenerate
// nil pointer comparisons.
//
// # Analyzer nilness
//
// nilness: check for redundant or impossible nil comparisons
//
// The nilness checker inspects the control-flow graph of each function in
// a package and reports nil pointer dereferences, degenerate nil
// pointers, and panics with nil values. A degenerate comparison is of the form
// x==nil or x!=nil where x is statically known to be nil or non-nil. These are
// often a mistake, especially in control flow related to errors. Panics with nil
// values are checked because they are not detectable by
//
//	if r := recover(); r != nil {
//
// This check reports conditions such as:
//
//	if f == nil { // impossible condition (f is a function)
//	}
//
// and:
//
//	p := &v
//	...
//	if p != nil { // tautological condition
//	}
//
// and:
//
//	if p == nil {
//		print(*p) // nil dereference
//	}
//
// and:
//
//	if p == nil {
//		panic(p)
//	}
//
// Sometimes the control flow may be quite complex, making bugs hard
// to spot. In the example below, the err.Error expression is
// guaranteed to panic because, after the first return, err must be
// nil. The intervening loop is just a distraction.
//
//	...
//	err := g.Wait()
//	if err != nil {
//		return err
//	}
//	partialSuccess := false
//	for _, err := range errs {
//		if err == nil {
//			partialSuccess = true
//			break
//		}
//	}
//	if partialSuccess {
//		reportStatus(StatusMessage{
//			Code:   code.ERROR,
//			Detail: err.Error(), // "nil dereference in dynamic method call"
//		})
//		return nil
//	}
//
// ...
package nilness


================================================
FILE: go/analysis/passes/nilness/nilness.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nilness

import (
	_ "embed"
	"fmt"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/buildssa"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typeparams"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "nilness",
	Doc:      analyzerutil.MustExtractDoc(doc, "nilness"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilness",
	Run:      run,
	Requires: []*analysis.Analyzer{buildssa.Analyzer},
}

func run(pass *analysis.Pass) (any, error) {
	ssainput := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
	for _, fn := range ssainput.SrcFuncs {
		runFunc(pass, fn)
	}
	return nil, nil
}

func runFunc(pass *analysis.Pass, fn *ssa.Function) {
	reportf := func(category string, pos token.Pos, format string, args ...any) {
		// We ignore nil-checking ssa.Instructions
		// that don't correspond to syntax.
		if pos.IsValid() {
			pass.Report(analysis.Diagnostic{
				Pos:      pos,
				Category: category,
				Message:  fmt.Sprintf(format, args...),
			})
		}
	}

	// notNil reports an error if v is provably nil.
	notNil := func(stack []fact, instr ssa.Instruction, v ssa.Value, descr string) {
		if nilnessOf(stack, v) == isnil {
			reportf("nilderef", instr.Pos(), "%s", descr)
		}
	}

	// visit visits reachable blocks of the CFG in dominance order,
	// maintaining a stack of dominating nilness facts.
	//
	// By traversing the dom tree, we can pop facts off the stack as
	// soon as we've visited a subtree.  Had we traversed the CFG,
	// we would need to retain the set of facts for each block.
	seen := make([]bool, len(fn.Blocks)) // seen[i] means visit should ignore block i
	var visit func(b *ssa.BasicBlock, stack []fact)
	visit = func(b *ssa.BasicBlock, stack []fact) {
		if seen[b.Index] {
			return
		}
		seen[b.Index] = true

		// Report nil dereferences.
		for _, instr := range b.Instrs {
			switch instr := instr.(type) {
			case ssa.CallInstruction:
				// A nil receiver may be okay for type params.
				cc := instr.Common()
				if !(cc.IsInvoke() && typeparams.IsTypeParam(cc.Value.Type())) {
					notNil(stack, instr, cc.Value, "nil dereference in "+cc.Description())
				}
			case *ssa.FieldAddr:
				notNil(stack, instr, instr.X, "nil dereference in field selection")
			case *ssa.IndexAddr:
				switch typeparams.CoreType(instr.X.Type()).(type) {
				case *types.Pointer: // *array
					notNil(stack, instr, instr.X, "nil dereference in array index operation")
				case *types.Slice:
					// This is not necessarily a runtime error, because
					// it is usually dominated by a bounds check.
					if isRangeIndex(instr) {
						notNil(stack, instr, instr.X, "range of nil slice")
					} else {
						notNil(stack, instr, instr.X, "index of nil slice")
					}
				}
			case *ssa.MapUpdate:
				notNil(stack, instr, instr.Map, "nil dereference in map update")
			case *ssa.Range:
				// (Not a runtime error, but a likely mistake.)
				notNil(stack, instr, instr.X, "range over nil map")
			case *ssa.Slice:
				// A nilcheck occurs in ptr[:] iff ptr is a pointer to an array.
				if is[*types.Pointer](instr.X.Type().Underlying()) {
					notNil(stack, instr, instr.X, "nil dereference in slice operation")
				}
			case *ssa.Store:
				notNil(stack, instr, instr.Addr, "nil dereference in store")
			case *ssa.TypeAssert:
				if !instr.CommaOk {
					notNil(stack, instr, instr.X, "nil dereference in type assertion")
				}
			case *ssa.UnOp:
				switch instr.Op {
				case token.MUL: // *X
					notNil(stack, instr, instr.X, "nil dereference in load")
				case token.ARROW: // <-ch
					// (Not a runtime error, but a likely mistake.)
					notNil(stack, instr, instr.X, "receive from nil channel")
				}
			case *ssa.Send:
				// (Not a runtime error, but a likely mistake.)
				notNil(stack, instr, instr.Chan, "send to nil channel")
			}
		}

		// Look for panics with nil value
		for _, instr := range b.Instrs {
			switch instr := instr.(type) {
			case *ssa.Panic:
				if nilnessOf(stack, instr.X) == isnil {
					reportf("nilpanic", instr.Pos(), "panic with nil value")
				}
			case *ssa.SliceToArrayPointer:
				nn := nilnessOf(stack, instr.X)
				if nn == isnil && slice2ArrayPtrLen(instr) > 0 {
					reportf("conversionpanic", instr.Pos(), "nil slice being cast to an array of len > 0 will always panic")
				}
			}
		}

		// For nil comparison blocks, report an error if the condition
		// is degenerate, and push a nilness fact on the stack when
		// visiting its true and false successor blocks.
		if binop, tsucc, fsucc := eq(b); binop != nil {
			xnil := nilnessOf(stack, binop.X)
			ynil := nilnessOf(stack, binop.Y)

			if ynil != unknown && xnil != unknown && (xnil == isnil || ynil == isnil) {
				// Degenerate condition:
				// the nilness of both operands is known,
				// and at least one of them is nil.
				var adj string
				if (xnil == ynil) == (binop.Op == token.EQL) {
					adj = "tautological"
				} else {
					adj = "impossible"
				}
				reportf("cond", binop.Pos(), "%s condition: %s %s %s", adj, xnil, binop.Op, ynil)

				// If tsucc's or fsucc's sole incoming edge is impossible,
				// it is unreachable.  Prune traversal of it and
				// all the blocks it dominates.
				// (We could be more precise with full dataflow
				// analysis of control-flow joins.)
				var skip *ssa.BasicBlock
				if xnil == ynil {
					skip = fsucc
				} else {
					skip = tsucc
				}
				for _, d := range b.Dominees() {
					if d == skip && len(d.Preds) == 1 {
						continue
					}
					visit(d, stack)
				}
				return
			}

			// "if x == nil" or "if nil == y" condition; x, y are unknown.
			if xnil == isnil || ynil == isnil {
				var newFacts facts
				if xnil == isnil {
					// x is nil, y is unknown:
					// t successor learns y is nil.
					newFacts = expandFacts(fact{binop.Y, isnil})
				} else {
					// y is nil, x is unknown:
					// t successor learns x is nil.
					newFacts = expandFacts(fact{binop.X, isnil})
				}

				for _, d := range b.Dominees() {
					// Successor blocks learn a fact
					// only at non-critical edges.
					// (We could do be more precise with full dataflow
					// analysis of control-flow joins.)
					s := stack
					if len(d.Preds) == 1 {
						if d == tsucc {
							s = append(s, newFacts...)
						} else if d == fsucc {
							s = append(s, newFacts.negate()...)
						}
					}
					visit(d, s)
				}
				return
			}
		}

		// In code of the form:
		//
		// 	if ptr, ok := x.(*T); ok { ... } else { fsucc }
		//
		// the fsucc block learns that ptr == nil,
		// since that's its zero value.
		if If, ok := b.Instrs[len(b.Instrs)-1].(*ssa.If); ok {
			// Handle "if ok" and "if !ok" variants.
			cond, fsucc := If.Cond, b.Succs[1]
			if unop, ok := cond.(*ssa.UnOp); ok && unop.Op == token.NOT {
				cond, fsucc = unop.X, b.Succs[0]
			}

			// Match pattern:
			//   t0 = typeassert (pointerlike)
			//   t1 = extract t0 #0  // ptr
			//   t2 = extract t0 #1  // ok
			//   if t2 goto tsucc, fsucc
			if extract1, ok := cond.(*ssa.Extract); ok && extract1.Index == 1 {
				if assert, ok := extract1.Tuple.(*ssa.TypeAssert); ok &&
					isNillable(assert.AssertedType) {
					for _, pinstr := range *assert.Referrers() {
						if extract0, ok := pinstr.(*ssa.Extract); ok &&
							extract0.Index == 0 &&
							extract0.Tuple == extract1.Tuple {
							for _, d := range b.Dominees() {
								if len(d.Preds) == 1 && d == fsucc {
									visit(d, append(stack, fact{extract0, isnil}))
								}
							}
						}
					}
				}
			}
		}

		for _, d := range b.Dominees() {
			visit(d, stack)
		}
	}

	// Visit the entry block.  No need to visit fn.Recover.
	if fn.Blocks != nil {
		visit(fn.Blocks[0], make([]fact, 0, 20)) // 20 is plenty
	}
}

// A fact records that a block is dominated
// by the condition v == nil or v != nil.
type fact struct {
	value   ssa.Value
	nilness nilness
}

func (f fact) negate() fact { return fact{f.value, -f.nilness} }

type nilness int

const (
	isnonnil         = -1
	unknown  nilness = 0
	isnil            = 1
)

var nilnessStrings = []string{"non-nil", "unknown", "nil"}

func (n nilness) String() string { return nilnessStrings[n+1] }

// nilnessOf reports whether v is definitely nil, definitely not nil,
// or unknown given the dominating stack of facts.
func nilnessOf(stack []fact, v ssa.Value) nilness {

	switch v := v.(type) {
	// unwrap ChangeInterface and Slice values recursively, to detect if underlying
	// values have any facts recorded or are otherwise known with regard to nilness.
	//
	// This work must be in addition to expanding facts about
	// ChangeInterfaces during inference/fact gathering because this covers
	// cases where the nilness of a value is intrinsic, rather than based
	// on inferred facts, such as a zero value interface variable. That
	// said, this work alone would only inform us when facts are about
	// underlying values, rather than outer values, when the analysis is
	// transitive in both directions.
	case *ssa.ChangeInterface:
		if underlying := nilnessOf(stack, v.X); underlying != unknown {
			return underlying
		}
	case *ssa.MakeInterface:
		// A MakeInterface is non-nil unless its operand is a type parameter.
		tparam, ok := types.Unalias(v.X.Type()).(*types.TypeParam)
		if !ok {
			return isnonnil
		}

		// A MakeInterface of a type parameter is non-nil if
		// the type parameter cannot be instantiated as an
		// interface type (#66835).
		if terms, err := typeparams.NormalTerms(tparam.Constraint()); err == nil && len(terms) > 0 {
			return isnonnil
		}

		// If the type parameter can be instantiated as an
		// interface (and thus also as a concrete type),
		// we can't determine the nilness.

	case *ssa.Slice:
		if underlying := nilnessOf(stack, v.X); underlying != unknown {
			return underlying
		}
	case *ssa.SliceToArrayPointer:
		nn := nilnessOf(stack, v.X)
		if slice2ArrayPtrLen(v) > 0 {
			if nn == isnil {
				// We know that *(*[1]byte)(nil) is going to panic because of the
				// conversion. So return unknown to the caller, prevent useless
				// nil deference reporting due to * operator.
				return unknown
			}
			// Otherwise, the conversion will yield a non-nil pointer to array.
			// Note that the instruction can still panic if array length greater
			// than slice length. If the value is used by another instruction,
			// that instruction can assume the panic did not happen when that
			// instruction is reached.
			return isnonnil
		}
		// In case array length is zero, the conversion result depends on nilness of the slice.
		if nn != unknown {
			return nn
		}
	}

	// Is value intrinsically nil or non-nil?
	switch v := v.(type) {
	case *ssa.Alloc,
		*ssa.FieldAddr,
		*ssa.FreeVar,
		*ssa.Function,
		*ssa.Global,
		*ssa.IndexAddr,
		*ssa.MakeChan,
		*ssa.MakeClosure,
		*ssa.MakeMap,
		*ssa.MakeSlice:
		return isnonnil

	case *ssa.Const:
		if v.IsNil() {
			return isnil // nil or zero value of a pointer-like type
		} else {
			return unknown // non-pointer
		}
	}

	// Search dominating control-flow facts.
	for _, f := range stack {
		if f.value == v {
			return f.nilness
		}
	}
	return unknown
}

func slice2ArrayPtrLen(v *ssa.SliceToArrayPointer) int64 {
	return v.Type().(*types.Pointer).Elem().Underlying().(*types.Array).Len()
}

// If b ends with an equality comparison, eq returns the operation and
// its true (equal) and false (not equal) successors.
func eq(b *ssa.BasicBlock) (op *ssa.BinOp, tsucc, fsucc *ssa.BasicBlock) {
	if If, ok := b.Instrs[len(b.Instrs)-1].(*ssa.If); ok {
		if binop, ok := If.Cond.(*ssa.BinOp); ok {
			switch binop.Op {
			case token.EQL:
				return binop, b.Succs[0], b.Succs[1]
			case token.NEQ:
				return binop, b.Succs[1], b.Succs[0]
			}
		}
	}
	return nil, nil, nil
}

// expandFacts takes a single fact and returns the set of facts that can be
// known about it or any of its related values. Some operations, like
// ChangeInterface, have transitive nilness, such that if you know the
// underlying value is nil, you also know the value itself is nil, and vice
// versa. This operation allows callers to match on any of the related values
// in analyses, rather than just the one form of the value that happened to
// appear in a comparison.
//
// This work must be in addition to unwrapping values within nilnessOf because
// while this work helps give facts about transitively known values based on
// inferred facts, the recursive check within nilnessOf covers cases where
// nilness facts are intrinsic to the underlying value, such as a zero value
// interface variables.
//
// ChangeInterface is the only expansion currently supported, but others, like
// Slice, could be added. At this time, this tool does not check slice
// operations in a way this expansion could help. See
// https://play.golang.org/p/mGqXEp7w4fR for an example.
func expandFacts(f fact) []fact {
	ff := []fact{f}

Loop:
	for {
		switch v := f.value.(type) {
		case *ssa.ChangeInterface:
			f = fact{v.X, f.nilness}
			ff = append(ff, f)
		default:
			break Loop
		}
	}

	return ff
}

type facts []fact

func (ff facts) negate() facts {
	nn := make([]fact, len(ff))
	for i, f := range ff {
		nn[i] = f.negate()
	}
	return nn
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

func isNillable(t types.Type) bool {
	// TODO(adonovan): CoreType (+ case *Interface) looks wrong.
	// This should probably use Underlying, and handle TypeParam
	// by computing the union across its normal terms.
	switch t := typeparams.CoreType(t).(type) {
	case *types.Pointer,
		*types.Map,
		*types.Signature,
		*types.Chan,
		*types.Interface,
		*types.Slice:
		return true
	case *types.Basic:
		return t == types.Typ[types.UnsafePointer]
	}
	return false
}

// isRangeIndex reports whether the instruction is a slice indexing
// operation slice[i] within a "for range slice" loop. The operation
// could be explicit, such as slice[i] within (or even after) the
// loop, or it could be implicit, such as "for i, v := range slice {}".
// (These cannot be reliably distinguished.)
func isRangeIndex(instr *ssa.IndexAddr) bool {
	// Here we reverse-engineer the go/ssa lowering of range-over-slice:
	//
	//      n = len(x)
	//      jump loop
	// loop:                                                "rangeindex.loop"
	//      phi = φ(-1, incr) #rangeindex
	//      incr = phi + 1
	//      cond = incr < n
	//      if cond goto body else done
	// body:                                                "rangeindex.body"
	//      instr = &x[incr]
	//      ...
	// done:
	if incr, ok := instr.Index.(*ssa.BinOp); ok && incr.Op == token.ADD {
		if b := incr.Block(); b.Comment == "rangeindex.loop" {
			if If, ok := b.Instrs[len(b.Instrs)-1].(*ssa.If); ok {
				if cond := If.Cond.(*ssa.BinOp); cond.X == incr && cond.Op == token.LSS {
					if call, ok := cond.Y.(*ssa.Call); ok {
						common := call.Common()
						if blt, ok := common.Value.(*ssa.Builtin); ok && blt.Name() == "len" {
							return common.Args[0] == instr.X
						}
					}
				}
			}
		}
	}
	return false
}


================================================
FILE: go/analysis/passes/nilness/nilness_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nilness_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/nilness"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, nilness.Analyzer, "a")
}

func TestNilness(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, nilness.Analyzer, "b")
}

func TestInstantiated(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, nilness.Analyzer, "c")
}

func TestTypeSet(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, nilness.Analyzer, "d")
}


================================================
FILE: go/analysis/passes/nilness/testdata/src/a/a.go
================================================
package a

import (
	"log"
	"os"
)

type X struct{ f, g int }

func f(x, y *X) {
	if x == nil {
		print(x.f) // want "nil dereference in field selection"
	} else {
		print(x.f)
	}

	if x == nil {
		if nil != y {
			print(1)
			panic(0)
		}
		x.f = 1 // want "nil dereference in field selection"
		y.f = 1 // want "nil dereference in field selection"
	}

	var f func()
	if f == nil { // want "tautological condition: nil == nil"
		go f() // want "nil dereference in dynamic function call"
	} else {
		// This block is unreachable,
		// so we don't report an error for the
		// nil dereference in the call.
		defer f()
	}
}

func f2(ptr *[3]int, i interface{}) {
	if ptr != nil {
		print(ptr[:])
		*ptr = [3]int{}
		print(*ptr)
	} else {
		print(ptr[:])   // want "nil dereference in slice operation"
		*ptr = [3]int{} // want "nil dereference in store"
		print(*ptr)     // want "nil dereference in load"

		if ptr != nil { // want "impossible condition: nil != nil"
			// Dominated by ptr==nil and ptr!=nil,
			// this block is unreachable.
			// We do not report errors within it.
			print(*ptr)
		}
	}

	if i != nil {
		print(i.(interface{ f() }))
	} else {
		print(i.(interface{ f() })) // want "nil dereference in type assertion"
	}
}

func g() error { return nil }

func f3() error {
	err := g()
	if err != nil {
		return err
	}
	if err != nil && err.Error() == "foo" { // want "impossible condition: nil != nil"
		print(0)
	}
	ch := make(chan int)
	if ch == nil { // want "impossible condition: non-nil == nil"
		print(0)
	}
	if ch != nil { // want "tautological condition: non-nil != nil"
		print(0)
	}
	return nil
}

func h(err error, b bool) {
	if err != nil && b {
		return
	} else if err != nil {
		panic(err)
	}
}

func i(*int) error {
	for {
		if err := g(); err != nil {
			return err
		}
	}
}

func f4(x *X) {
	if x == nil {
		panic(x)
	}
}

func f5(x *X) {
	panic(nil) // want "panic with nil value"
}

func f6(x *X) {
	var err error
	panic(err) // want "panic with nil value"
}

func f7() {
	x, err := bad()
	if err != nil {
		panic(0)
	}
	if x == nil {
		panic(err) // want "panic with nil value"
	}
}

func bad() (*X, error) {
	return nil, nil
}

func f8() {
	var e error
	v, _ := e.(interface{})
	print(v)
}

func f9(x interface {
	a()
	b()
	c()
}) {
	x.b() // we don't catch this panic because we don't have any facts yet
	xx := interface {
		a()
		b()
	}(x)
	if xx != nil {
		return
	}
	x.c()  // want "nil dereference in dynamic method call"
	xx.b() // want "nil dereference in dynamic method call"
	xxx := interface{ a() }(xx)
	xxx.a() // want "nil dereference in dynamic method call"

	if unknown() {
		panic(x) // want "panic with nil value"
	}
	if unknown() {
		panic(xx) // want "panic with nil value"
	}
	if unknown() {
		panic(xxx) // want "panic with nil value"
	}
}

func f10() {
	s0 := make([]string, 0)
	if s0 == nil { // want "impossible condition: non-nil == nil"
		print(0)
	}

	var s1 []string
	if s1 == nil { // want "tautological condition: nil == nil"
		print(0)
	}
	s2 := s1[:][:]
	if s2 == nil { // want "tautological condition: nil == nil"
		print(0)
	}
}

func unknown() bool {
	return false
}

func f11(a interface{}) {
	switch a.(type) {
	case nil:
		return
	}
	switch a.(type) {
	case nil: // want "impossible condition: non-nil == nil"
		return
	}
}

func f12(a interface{}) {
	switch a {
	case nil:
		return
	}
	switch a {
	case 5,
		nil: // want "impossible condition: non-nil == nil"
		return
	}
}

type Y struct {
	innerY
}

type innerY struct {
	value int
}

func f13() {
	var d *Y
	print(d.value) // want "nil dereference in field selection"
}

func f14() {
	var x struct{ f string }
	if x == struct{ f string }{} { // we don't catch this tautology as we restrict to reference types
		print(x)
	}
}

func f15(x any) {
	ptr, ok := x.(*int)
	if ok {
		return
	}
	println(*ptr) // want "nil dereference in load"
}

func f16(x any) {
	ptr, ok := x.(*int)
	if !ok {
		println(*ptr) // want "nil dereference in load"
		return
	}
	println(*ptr)
}

func f18(x any) {
	ptr, ok := x.(*int)
	if ok {
		println(ptr)
		// falls through
	}
	println(*ptr)
}

// Regression test for https://github.com/golang/go/issues/65674:
// spurious "nil deference in slice index operation" when the
// index was subject to a range loop.
func f19(slice []int, array *[2]int, m map[string]int, ch chan int) {
	if slice == nil {
		// A range over a nil slice is dynamically benign,
		// but still signifies a programmer mistake.
		//
		// Since SSA has melted down the control structure,
		// so we can only report a diagnostic about the
		// index operation, with heuristics for "range".

		for range slice { // nothing to report here
		}
		for _, v := range slice { // want "range of nil slice"
			_ = v
		}
		for i := range slice {
			_ = slice[i] // want "range of nil slice"
		}
		{
			var i int
			for i = range slice {
			}
			_ = slice[i] // want "index of nil slice"
		}
		for i := range slice {
			if i < len(slice) {
				_ = slice[i] // want "range of nil slice"
			}
		}
		if len(slice) > 3 {
			_ = slice[2] // want "index of nil slice"
		}
		for i := 0; i < len(slice); i++ {
			_ = slice[i] // want "index of nil slice"
		}
	}

	if array == nil {
		// (The v var is necessary, otherwise the SSA
		// code doesn't dereference the pointer.)
		for _, v := range array { // want "nil dereference in array index operation"
			_ = v
		}
	}

	if m == nil {
		for range m { // want "range over nil map"
		}
		m["one"] = 1 // want "nil dereference in map update"
	}

	if ch == nil {
		for range ch { // want "receive from nil channel"
		}
		<-ch    // want "receive from nil channel"
		ch <- 0 // want "send to nil channel"
	}
}

func f20() {
	f, err := os.Open("")
	if err != nil {
		log.Fatal(err) // noreturn analysis proves this call doesn't return
	}
	if err != nil { // want "impossible condition"
		log.Fatal(err)
	}
	f.Close()
}


================================================
FILE: go/analysis/passes/nilness/testdata/src/b/b.go
================================================
package b

func f() {
	var s []int
	t := (*[0]int)(s)
	_ = *t // want "nil dereference in load"
	_ = (*[0]int)(s)
	_ = *(*[0]int)(s) // want "nil dereference in load"

	// these operation is panic
	_ = (*[1]int)(s)  // want "nil slice being cast to an array of len > 0 will always panic"
	_ = *(*[1]int)(s) // want "nil slice being cast to an array of len > 0 will always panic"
}

func g() {
	var s = make([]int, 0)
	t := (*[0]int)(s)
	println(*t)
}

func h() {
	var s = make([]int, 1)
	t := (*[1]int)(s)
	println(*t)
}

func i(x []int) {
	a := (*[1]int)(x)
	if a != nil { // want "tautological condition: non-nil != nil"
		_ = *a
	}
}

func _(err error) {
	if err == nil {
		err.Error() // want "nil dereference in dynamic method call"

		// SSA uses TypeAssert for the nil check in a method value:
		_ = err.Error // want "nil dereference in type assertion"
	}
}


================================================
FILE: go/analysis/passes/nilness/testdata/src/c/c.go
================================================
package c

func instantiated[X any](x *X) int {
	if x == nil {
		print(*x) // want "nil dereference in load"
	}
	return 1
}

var g int

func init() {
	g = instantiated[int](&g)
}

// -- issue 66835 --

type Empty1 any
type Empty2 any

// T may be instantiated with an interface type, so any(x) may be nil.
func TypeParamInterface[T error](x T) {
	if any(x) == nil {
		print()
	}
}

// T may not be instantiated with an interface type, so any(x) is non-nil
func TypeParamTypeSetWithInt[T interface {
	error
	int
}](x T) {
	if any(x) == nil { // want "impossible condition: non-nil == nil"
		print()
	}
}

func TypeParamUnionEmptyEmpty[T Empty1 | Empty2](x T) {
	if any(x) == nil {
		print()
	}
}

func TypeParamUnionEmptyInt[T Empty1 | int](x T) {
	if any(x) == nil {
		print()
	}
}

func TypeParamUnionStringInt[T string | int](x T) {
	if any(x) == nil { // want "impossible condition: non-nil == nil"
		print()
	}
}


================================================
FILE: go/analysis/passes/nilness/testdata/src/d/d.go
================================================
package d

type message interface{ PR() }

func noparam() {
	var messageT message
	messageT.PR() // want "nil dereference in dynamic method call"
}

func paramNonnil[T message]() {
	var messageT T
	messageT.PR() // cannot conclude messageT is nil.
}

func instance() {
	// buildssa.BuilderMode does not include InstantiateGenerics.
	paramNonnil[message]() // no warning is expected as param[message] id not built.
}

func param[T interface {
	message
	~*int | ~chan int
}]() {
	var messageT T // messageT is nil.
	messageT.PR()  // nil receiver may be okay. See param[nilMsg].
}

type nilMsg chan int

func (m nilMsg) PR() {
	if m == nil {
		print("not an error")
	}
}

var G func() = param[nilMsg] // no warning

func allNillable[T ~*int | ~chan int]() {
	var x, y T  // both are nillable and are nil.
	if x != y { // want "impossible condition: nil != nil"
		print("unreachable")
	}
}

func notAll[T ~*int | ~chan int | ~int]() {
	var x, y T  // neither are nillable due to ~int
	if x != y { // no warning
		print("unreachable")
	}
}

func noninvoke[T ~func()]() {
	var x T
	x() // want "nil dereference in dynamic function call"
}


================================================
FILE: go/analysis/passes/pkgfact/pkgfact.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The pkgfact package is a demonstration and test of the package fact
// mechanism.
//
// The output of the pkgfact analysis is a set of key/values pairs
// gathered from the analyzed package and its imported dependencies.
// Each key/value pair comes from a top-level constant declaration
// whose name starts and ends with "_".  For example:
//
//	package p
//
//	const _greeting_  = "hello"
//	const _audience_  = "world"
//
// the pkgfact analysis output for package p would be:
//
//	{"greeting": "hello", "audience": "world"}.
//
// In addition, the analysis reports a diagnostic at each import
// showing which key/value pairs it contributes.
package pkgfact

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"reflect"
	"sort"
	"strings"

	"golang.org/x/tools/go/analysis"
)

var Analyzer = &analysis.Analyzer{
	Name:       "pkgfact",
	Doc:        "gather name/value pairs from constant declarations",
	URL:        "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/pkgfact",
	Run:        run,
	FactTypes:  []analysis.Fact{new(pairsFact)},
	ResultType: reflect.TypeFor[map[string]string](),
}

// A pairsFact is a package-level fact that records
// a set of key=value strings accumulated from constant
// declarations in this package and its dependencies.
// Elements are ordered by keys, which are unique.
type pairsFact []string

func (f *pairsFact) AFact()         {}
func (f *pairsFact) String() string { return "pairs(" + strings.Join(*f, ", ") + ")" }

func run(pass *analysis.Pass) (any, error) {
	result := make(map[string]string)

	// At each import, print the fact from the imported
	// package and accumulate its information into the result.
	// (Warning: accumulation leads to quadratic growth of work.)
	doImport := func(spec *ast.ImportSpec) {
		pkg := imported(pass.TypesInfo, spec)
		var fact pairsFact
		if pass.ImportPackageFact(pkg, &fact) {
			for _, pair := range fact {
				eq := strings.IndexByte(pair, '=')
				result[pair[:eq]] = pair[1+eq:]
			}
			pass.ReportRangef(spec, "%s", strings.Join(fact, " "))
		}
	}

	// At each "const _name_ = value", add a fact into env.
	doConst := func(spec *ast.ValueSpec) {
		if len(spec.Names) == len(spec.Values) {
			for i := range spec.Names {
				name := spec.Names[i].Name
				if strings.HasPrefix(name, "_") && strings.HasSuffix(name, "_") {

					if key := strings.Trim(name, "_"); key != "" {
						value := pass.TypesInfo.Types[spec.Values[i]].Value.String()
						result[key] = value
					}
				}
			}
		}
	}

	for _, f := range pass.Files {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.GenDecl); ok {
				for _, spec := range decl.Specs {
					switch decl.Tok {
					case token.IMPORT:
						doImport(spec.(*ast.ImportSpec))
					case token.CONST:
						doConst(spec.(*ast.ValueSpec))
					}
				}
			}
		}
	}

	// Sort/deduplicate the result and save it as a package fact.
	keys := make([]string, 0, len(result))
	for key := range result {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	var fact pairsFact
	for _, key := range keys {
		fact = append(fact, fmt.Sprintf("%s=%s", key, result[key]))
	}
	if len(fact) > 0 {
		pass.ExportPackageFact(&fact)
	}

	return result, nil
}

func imported(info *types.Info, spec *ast.ImportSpec) *types.Package {
	obj, ok := info.Implicits[spec]
	if !ok {
		obj = info.Defs[spec.Name] // renaming import
	}
	return obj.(*types.PkgName).Imported()
}


================================================
FILE: go/analysis/passes/pkgfact/pkgfact_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgfact_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/pkgfact"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, pkgfact.Analyzer, "c")
}


================================================
FILE: go/analysis/passes/pkgfact/testdata/src/a/a.go
================================================
package a

const _greeting_ = "hello"
const _audience_ = "world"


================================================
FILE: go/analysis/passes/pkgfact/testdata/src/b/b.go
================================================
package b

import _ "a"

const _pi_ = 3.14159


================================================
FILE: go/analysis/passes/pkgfact/testdata/src/c/c.go
================================================
// want package:`pairs\(audience="world", greeting="hello", pi=3.14159\)`

package c

import _ "b" // want `audience="world" greeting="hello" pi=3.14159`


================================================
FILE: go/analysis/passes/printf/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package printf defines an Analyzer that checks consistency
// of Printf format strings and arguments.
//
// # Analyzer printf
//
// printf: check consistency of Printf format strings and arguments
//
// The check applies to calls of the formatting functions such as
// [fmt.Printf] and [fmt.Sprintf], as well as any detected wrappers of
// those functions such as [log.Printf]. It reports a variety of
// mistakes such as syntax errors in the format string and mismatches
// (of number and type) between the verbs and their arguments.
//
// See the documentation of the fmt package for the complete set of
// format operators and their operand types.
//
// # Examples
//
// The %d format operator requires an integer operand.
// Here it is incorrectly applied to a string:
//
//	fmt.Printf("%d", "hello") // fmt.Printf format %d has arg "hello" of wrong type string
//
// A call to Printf must have as many operands as there are "verbs" in
// the format string, not too few:
//
//	fmt.Printf("%d") // fmt.Printf format reads arg 1, but call has 0 args
//
// nor too many:
//
//	fmt.Printf("%d", 1, 2) // fmt.Printf call needs 1 arg, but has 2 args
//
// Explicit argument indexes must be no greater than the number of
// arguments:
//
//	fmt.Printf("%[3]d", 1, 2) // fmt.Printf call has invalid argument index 3
//
// The checker also uses a heuristic to report calls to Print-like
// functions that appear to have been intended for their Printf-like
// counterpart:
//
//	log.Print("%d", 123) // log.Print call has possible formatting directive %d
//
// Conversely, it also reports calls to Printf-like functions with a
// non-constant format string and no other arguments:
//
//	fmt.Printf(message) // non-constant format string in call to fmt.Printf
//
// Such calls may have been intended for the function's Print-like
// counterpart: if the value of message happens to contain "%",
// misformatting will occur. In this case, the checker additionally
// suggests a fix to turn the call into:
//
//	fmt.Printf("%s", message)
//
// # Inferred printf wrappers
//
// Functions that delegate their arguments to fmt.Printf are
// considered "printf wrappers"; calls to them are subject to the same
// checking. In this example, logf is a printf wrapper:
//
//	func logf(level int, format string, args ...any) {
//		if enabled(level) {
//			log.Printf(format, args...)
//		}
//	}
//
//	logf(3, "invalid request: %v") // logf format reads arg 1, but call has 0 args
//
// To enable printf checking on a function that is not found by this
// analyzer's heuristics (for example, because control is obscured by
// dynamic method calls), insert a bogus call:
//
//	func MyPrintf(format string, args ...any) {
//		if false {
//			_ = fmt.Sprintf(format, args...) // enable printf checking
//		}
//		...
//	}
//
// A local function may also be inferred as a printf wrapper. If it
// is assigned to a variable, each call made through that variable will
// be checked just like a call to a function:
//
//	logf := func(format string, args ...any) {
//		message := fmt.Sprintf(format, args...)
//		log.Printf("%s: %s", prefix, message)
//	}
//	logf("%s", 123) // logf format %s has arg 123 of wrong type int
//
// Interface methods may also be analyzed as printf wrappers, if
// within the interface's package there is an assignment from a
// implementation type whose corresponding method is a printf wrapper.
//
// For example, the var declaration below causes a *myLoggerImpl value
// to be assigned to a Logger variable:
//
//	type Logger interface {
//		Logf(format string, args ...any)
//	}
//
//	type myLoggerImpl struct{ ... }
//
//	var _ Logger = (*myLoggerImpl)(nil)
//
//	func  (*myLoggerImpl) Logf(format string, args ...any) {
//		println(fmt.Sprintf(format, args...))
//	}
//
// Since myLoggerImpl's Logf method is a printf wrapper, this
// establishes that Logger.Logf is a printf wrapper too, causing
// dynamic calls through the interface to be checked:
//
//	func f(log Logger) {
//		log.Logf("%s", 123) // Logger.Logf format %s has arg 123 of wrong type int
//	}
//
// This feature applies only to interface methods declared in files
// using at least Go 1.26.
//
// # Specifying printf wrappers by flag
//
// The -funcs flag specifies a comma-separated list of names of
// additional known formatting functions or methods. (This legacy flag
// is rarely used due to the automatic inference described above.)
//
// If the name contains a period, it must denote a specific function
// using one of the following forms:
//
//	dir/pkg.Function
//	dir/pkg.Type.Method
//	(*dir/pkg.Type).Method
//
// Otherwise the name is interpreted as a case-insensitive unqualified
// identifier such as "errorf". Either way, if a listed name ends in f, the
// function is assumed to be Printf-like, taking a format string before the
// argument list. Otherwise it is assumed to be Print-like, taking a list
// of arguments with no format string.
package printf


================================================
FILE: go/analysis/passes/printf/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The printf command applies the printf checker to the specified
// packages of Go source code.
//
// Run with:
//
//	$ go run ./go/analysis/passes/printf/main.go -- packages...
package main

import (
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(printf.Analyzer) }


================================================
FILE: go/analysis/passes/printf/printf.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package printf

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"reflect"
	"regexp"
	"sort"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/fmtstr"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
	"golang.org/x/tools/refactor/satisfy"
)

func init() {
	Analyzer.Flags.Var(isPrint, "funcs", "comma-separated list of print function names to check")
}

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:       "printf",
	Doc:        analyzerutil.MustExtractDoc(doc, "printf"),
	URL:        "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/printf",
	Requires:   []*analysis.Analyzer{inspect.Analyzer},
	Run:        run,
	ResultType: reflect.TypeFor[*Result](),
	FactTypes:  []analysis.Fact{new(isWrapper)},
}

// Kind is a kind of fmt function behavior.
type Kind int

const (
	KindNone   Kind = iota // not a fmt wrapper function
	KindPrint              // function behaves like fmt.Print
	KindPrintf             // function behaves like fmt.Printf
	KindErrorf             // function behaves like fmt.Errorf
)

func (kind Kind) String() string {
	switch kind {
	case KindPrint:
		return "print"
	case KindPrintf:
		return "printf"
	case KindErrorf:
		return "errorf"
	}
	return "(none)"
}

// Result is the printf analyzer's result type. Clients may query the result
// to learn whether a function behaves like fmt.Print or fmt.Printf.
type Result struct {
	funcs map[types.Object]Kind
}

// Kind reports whether fn behaves like fmt.Print or fmt.Printf.
func (r *Result) Kind(fn *types.Func) Kind {
	_, ok := isPrint[fn.FullName()]
	if !ok {
		// Next look up just "printf", for use with -printf.funcs.
		_, ok = isPrint[strings.ToLower(fn.Name())]
	}
	if ok {
		if strings.HasSuffix(fn.Name(), "f") {
			return KindPrintf
		} else {
			return KindPrint
		}
	}

	return r.funcs[fn]
}

// isWrapper is a fact indicating that a function is a print or printf wrapper.
type isWrapper struct{ Kind Kind }

func (f *isWrapper) AFact() {}

func (f *isWrapper) String() string {
	switch f.Kind {
	case KindPrintf:
		return "printfWrapper"
	case KindPrint:
		return "printWrapper"
	case KindErrorf:
		return "errorfWrapper"
	default:
		return "unknownWrapper"
	}
}

func run(pass *analysis.Pass) (any, error) {
	res := &Result{
		funcs: make(map[types.Object]Kind),
	}
	findPrintLike(pass, res)
	checkCalls(pass, res)
	return res, nil
}

// A wrapper is a candidate print/printf wrapper function.
//
// We represent functions generally as types.Object, not *Func, so
// that we can analyze anonymous functions such as
//
//	printf := func(format string, args ...any) {...},
//
// representing them by the *types.Var symbol for the local variable
// 'printf'.
type wrapper struct {
	obj     types.Object     // *Func or *Var
	curBody inspector.Cursor // for *ast.BlockStmt
	format  *types.Var       // optional "format string" parameter in the Func{Decl,Lit}
	args    *types.Var       // "args ...any" parameter in the Func{Decl,Lit}
	callers []printfCaller
}

// printfCaller is a candidate print{,f} forwarding call from candidate wrapper w.
type printfCaller struct {
	w    *wrapper
	call *ast.CallExpr // forwarding call (nil for implicit interface method -> impl calls)
}

// formatArgsParams returns the "format string" and "args ...any"
// parameters of a potential print or printf wrapper function.
// (The format is nil in the print-like case.)
func formatArgsParams(sig *types.Signature) (format, args *types.Var) {
	if !sig.Variadic() {
		return nil, nil // not variadic
	}

	params := sig.Params()
	nparams := params.Len() // variadic => nonzero

	// Is second last param 'format string'?
	if nparams >= 2 {
		if p := params.At(nparams - 2); p.Type() == types.Typ[types.String] {
			format = p
		}
	}

	// Check final parameter is "args ...any".
	// (variadic => slice)
	args = params.At(nparams - 1)
	iface, ok := types.Unalias(args.Type().(*types.Slice).Elem()).(*types.Interface)
	if !ok || !iface.Empty() {
		return nil, nil
	}

	return format, args
}

// findPrintLike scans the entire package to find print or printf-like functions.
// When it returns, all such functions have been identified.
func findPrintLike(pass *analysis.Pass, res *Result) {
	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		info    = pass.TypesInfo
	)

	// Pass 1: gather candidate wrapper functions (and populate wrappers).
	var (
		wrappers []*wrapper
		byObj    = make(map[types.Object]*wrapper)
	)
	for cur := range inspect.Root().Preorder((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil), (*ast.InterfaceType)(nil)) {

		// addWrapper records that a func (or var representing
		// a FuncLit) is a potential print{,f} wrapper.
		// curBody is its *ast.BlockStmt, if any.
		addWrapper := func(obj types.Object, sig *types.Signature, curBody inspector.Cursor) *wrapper {
			format, args := formatArgsParams(sig)
			if args != nil {
				// obj (the symbol for a function/method, or variable
				// assigned to an anonymous function) is a potential
				// print or printf wrapper.
				//
				// Later processing will analyze the graph of potential
				// wrappers and their function bodies to pick out the
				// ones that are true wrappers.
				w := &wrapper{
					obj:     obj,
					curBody: curBody,
					format:  format, // non-nil => printf
					args:    args,
				}
				byObj[w.obj] = w
				wrappers = append(wrappers, w)
				return w
			}
			return nil
		}

		switch f := cur.Node().(type) {
		case *ast.FuncDecl:
			// named function or method:
			//
			//    func wrapf(format string, args ...any) {...}
			if f.Body != nil {
				fn := info.Defs[f.Name].(*types.Func)
				addWrapper(fn, fn.Signature(), cur.ChildAt(edge.FuncDecl_Body, -1))
			}

		case *ast.FuncLit:
			// anonymous function directly assigned to a variable:
			//
			//    var wrapf = func(format string, args ...any) {...}
			//    wrapf    := func(format string, args ...any) {...}
			//    wrapf     = func(format string, args ...any) {...}
			//
			// The LHS may also be a struct field x.wrapf or
			// an imported var pkg.Wrapf.
			//
			var lhs ast.Expr
			switch ek, idx := cur.ParentEdge(); ek {
			case edge.ValueSpec_Values:
				curName := cur.Parent().ChildAt(edge.ValueSpec_Names, idx)
				lhs = curName.Node().(*ast.Ident)
			case edge.AssignStmt_Rhs:
				curLhs := cur.Parent().ChildAt(edge.AssignStmt_Lhs, idx)
				lhs = curLhs.Node().(ast.Expr)
			}

			var v *types.Var
			switch lhs := lhs.(type) {
			case *ast.Ident:
				// variable: wrapf = func(...)
				v, _ = info.ObjectOf(lhs).(*types.Var)
			case *ast.SelectorExpr:
				if sel, ok := info.Selections[lhs]; ok {
					// struct field: x.wrapf = func(...)
					v = sel.Obj().(*types.Var)
				} else {
					// imported var: pkg.Wrapf = func(...)
					v = info.Uses[lhs.Sel].(*types.Var)
				}
			}
			if v != nil {
				sig := info.TypeOf(f).(*types.Signature)
				curBody := cur.ChildAt(edge.FuncLit_Body, -1)
				addWrapper(v, sig, curBody)
			}

		case *ast.InterfaceType:
			// Induction through interface methods is gated as
			// if it were a go1.26 language feature, to avoid
			// surprises when go test's vet suite gets stricter.
			if analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(cur), versions.Go1_26) {
				for imeth := range info.TypeOf(f).(*types.Interface).Methods() {
					addWrapper(imeth, imeth.Signature(), inspector.Cursor{})
				}
			}
		}
	}

	// impls maps abstract methods to implementations.
	//
	// Interface methods are modelled as if they have a body
	// that calls each implementing method.
	//
	// In the code below, impls maps Logger.Logf to
	// [myLogger.Logf], and if myLogger.Logf is discovered to be
	// printf-like, then so will be Logger.Logf.
	//
	//   type Logger interface {
	// 	Logf(format string, args ...any)
	//   }
	//   type myLogger struct{ ... }
	//   func (myLogger) Logf(format string, args ...any) {...}
	//   var _ Logger = myLogger{}
	impls := methodImplementations(pass)

	// doCall records a call from one wrapper to another.
	doCall := func(w *wrapper, callee types.Object, call *ast.CallExpr) {
		// Call from one wrapper candidate to another?
		// Record the edge so that if callee is found to be
		// a true wrapper, w will be too.
		if w2, ok := byObj[callee]; ok {
			w2.callers = append(w2.callers, printfCaller{w, call})
		}

		// Is the candidate a true wrapper, because it calls
		// a known print{,f}-like function from the allowlist
		// or an imported fact, or another wrapper found
		// to be a true wrapper?
		// If so, convert all w's callers to kind.
		kind := callKind(pass, callee, res)
		if kind != KindNone {
			propagate(pass, w, call, kind, res)
		}
	}

	// Pass 2: scan the body of each wrapper function
	// for calls to other printf-like functions.
	for _, w := range wrappers {

		// An interface method has no body, but acts
		// like an implicit call to each implementing method.
		if !w.curBody.Valid() {
			for impl := range impls[w.obj.(*types.Func)] {
				doCall(w, impl, nil)
			}
			continue // (no body)
		}

		// Process all calls in the wrapper function's body.
	scan:
		for cur := range w.curBody.Preorder(
			(*ast.AssignStmt)(nil),
			(*ast.UnaryExpr)(nil),
			(*ast.CallExpr)(nil),
		) {
			switch n := cur.Node().(type) {

			// Reject tricky cases where the parameters
			// are potentially mutated by AssignStmt or UnaryExpr.
			// (This logic checks for mutation only before the call.)
			// TODO: Relax these checks; issue 26555.

			case *ast.AssignStmt:
				// If the wrapper updates format or args
				// it is not a simple wrapper.
				for _, lhs := range n.Lhs {
					if w.format != nil && match(info, lhs, w.format) ||
						match(info, lhs, w.args) {
						break scan
					}
				}

			case *ast.UnaryExpr:
				// If the wrapper computes &format or &args,
				// it is not a simple wrapper.
				if n.Op == token.AND &&
					(w.format != nil && match(info, n.X, w.format) ||
						match(info, n.X, w.args)) {
					break scan
				}

			case *ast.CallExpr:
				if len(n.Args) > 0 && match(info, n.Args[len(n.Args)-1], w.args) {
					if callee := typeutil.Callee(pass.TypesInfo, n); callee != nil {
						doCall(w, callee, n)
					}
				}
			}
		}
	}
}

// methodImplementations returns the mapping from interface methods
// declared in this package to their corresponding implementing
// methods (which may also be interface methods), according to the set
// of assignments to interface types that appear within this package.
func methodImplementations(pass *analysis.Pass) map[*types.Func]map[*types.Func]bool {
	impls := make(map[*types.Func]map[*types.Func]bool)

	// To find interface/implementation relations,
	// we use the 'satisfy' pass, but proposal #70638
	// provides a better way.
	//
	// This pass over the syntax could be factored out as
	// a separate analysis pass if it is needed by other
	// analyzers.
	var f satisfy.Finder
	f.Find(pass.TypesInfo, pass.Files)
	for assign := range f.Result {
		// Have: LHS = RHS, where LHS is an interface type.
		for imeth := range assign.LHS.Underlying().(*types.Interface).Methods() {
			// Limit to interface methods of current package.
			if imeth.Pkg() != pass.Pkg {
				continue
			}

			if _, args := formatArgsParams(imeth.Signature()); args == nil {
				continue // not print{,f}-like
			}

			// Add implementing method to the set.
			impl, _, _ := types.LookupFieldOrMethod(assign.RHS, false, pass.Pkg, imeth.Name()) // can't fail
			set, ok := impls[imeth]
			if !ok {
				set = make(map[*types.Func]bool)
				impls[imeth] = set
			}
			set[impl.(*types.Func)] = true
		}
	}
	return impls
}

func match(info *types.Info, arg ast.Expr, param *types.Var) bool {
	id, ok := arg.(*ast.Ident)
	return ok && info.ObjectOf(id) == param
}

// propagate propagates changes in wrapper (non-None) kind information backwards
// through through the wrapper.callers graph of well-formed forwarding calls.
func propagate(pass *analysis.Pass, w *wrapper, call *ast.CallExpr, kind Kind, res *Result) {
	// Check correct call forwarding.
	//
	// Interface methods (call==nil) forward
	// correctly by construction.
	if call != nil && !checkForward(pass, w, call, kind) {
		return
	}

	// If the candidate's print{,f} status becomes known,
	// propagate it back to all its so-far known callers.
	if res.funcs[w.obj] != kind {
		res.funcs[w.obj] = kind

		// Export a fact.
		// (This is a no-op for local symbols.)
		// We can't export facts on a symbol of another package,
		// but we can treat the symbol as a wrapper within
		// the current analysis unit.
		if w.obj.Pkg() == pass.Pkg {
			// Facts are associated with origins.
			pass.ExportObjectFact(origin(w.obj), &isWrapper{Kind: kind})
		}

		// Propagate kind back to known callers.
		for _, caller := range w.callers {
			propagate(pass, caller.w, caller.call, kind, res)
		}
	}
}

// checkForward checks whether a call from wrapper w is a well-formed
// forwarding call of the specified (non-None) kind.
//
// If not, it reports a diagnostic that the user wrote
// fmt.Printf(format, args) instead of fmt.Printf(format, args...).
func checkForward(pass *analysis.Pass, w *wrapper, call *ast.CallExpr, kind Kind) bool {
	// Printf/Errorf calls must delegate the format string.
	switch kind {
	case KindPrintf, KindErrorf:
		if len(call.Args) < 2 || !match(pass.TypesInfo, call.Args[len(call.Args)-2], w.format) {
			return false
		}
	}

	// The args... delegation must be variadic.
	// (That args is actually delegated was
	// established before the root call to doCall.)
	if !call.Ellipsis.IsValid() {
		typ, ok := pass.TypesInfo.Types[call.Fun].Type.(*types.Signature)
		if !ok {
			return false
		}
		if len(call.Args) > typ.Params().Len() {
			// If we're passing more arguments than what the
			// print/printf function can take, adding an ellipsis
			// would break the program. For example:
			//
			//   func foo(arg1 string, arg2 ...interface{}) {
			//       fmt.Printf("%s %v", arg1, arg2)
			//   }
			return false
		}
		pass.ReportRangef(call, "missing ... in args forwarded to %s-like function", kind)
		return false
	}

	return true
}

func origin(obj types.Object) types.Object {
	switch obj := obj.(type) {
	case *types.Func:
		return obj.Origin()
	case *types.Var:
		return obj.Origin()
	}
	return obj
}

// isPrint records the print functions.
// If a key ends in 'f' then it is assumed to be a formatted print.
//
// Keys are either values returned by (*types.Func).FullName,
// or case-insensitive identifiers such as "errorf".
//
// The -funcs flag adds to this set.
//
// The set below includes facts for many important standard library
// functions, even though the analysis is capable of deducing that, for
// example, fmt.Printf forwards to fmt.Fprintf. We avoid relying on the
// driver applying analyzers to standard packages because "go vet" does
// not do so with gccgo, and nor do some other build systems.
var isPrint = stringSet{
	"fmt.Appendf":  true,
	"fmt.Append":   true,
	"fmt.Appendln": true,
	"fmt.Errorf":   true,
	"fmt.Fprint":   true,
	"fmt.Fprintf":  true,
	"fmt.Fprintln": true,
	"fmt.Print":    true,
	"fmt.Printf":   true,
	"fmt.Println":  true,
	"fmt.Sprint":   true,
	"fmt.Sprintf":  true,
	"fmt.Sprintln": true,

	"runtime/trace.Logf": true,

	"log.Print":             true,
	"log.Printf":            true,
	"log.Println":           true,
	"log.Fatal":             true,
	"log.Fatalf":            true,
	"log.Fatalln":           true,
	"log.Panic":             true,
	"log.Panicf":            true,
	"log.Panicln":           true,
	"(*log.Logger).Fatal":   true,
	"(*log.Logger).Fatalf":  true,
	"(*log.Logger).Fatalln": true,
	"(*log.Logger).Panic":   true,
	"(*log.Logger).Panicf":  true,
	"(*log.Logger).Panicln": true,
	"(*log.Logger).Print":   true,
	"(*log.Logger).Printf":  true,
	"(*log.Logger).Println": true,

	"(*testing.common).Error":  true,
	"(*testing.common).Errorf": true,
	"(*testing.common).Fatal":  true,
	"(*testing.common).Fatalf": true,
	"(*testing.common).Log":    true,
	"(*testing.common).Logf":   true,
	"(*testing.common).Skip":   true,
	"(*testing.common).Skipf":  true,
	"(testing.TB).Error":       true,
	"(testing.TB).Errorf":      true,
	"(testing.TB).Fatal":       true,
	"(testing.TB).Fatalf":      true,
	"(testing.TB).Log":         true,
	"(testing.TB).Logf":        true,
	"(testing.TB).Skip":        true,
	"(testing.TB).Skipf":       true,
}

// formatStringIndex returns the index of the format string (the last
// non-variadic parameter) within the given printf-like call
// expression, or -1 if unknown.
func formatStringIndex(pass *analysis.Pass, call *ast.CallExpr) int {
	typ := pass.TypesInfo.Types[call.Fun].Type
	if typ == nil {
		return -1 // missing type
	}
	sig, ok := typ.(*types.Signature)
	if !ok {
		return -1 // ill-typed
	}
	if !sig.Variadic() {
		// Skip checking non-variadic functions.
		return -1
	}
	idx := sig.Params().Len() - 2
	if idx < 0 {
		// Skip checking variadic functions without
		// fixed arguments.
		return -1
	}
	return idx
}

// stringConstantExpr returns expression's string constant value.
//
// ("", false) is returned if expression isn't a string
// constant.
func stringConstantExpr(pass *analysis.Pass, expr ast.Expr) (string, bool) {
	lit := pass.TypesInfo.Types[expr].Value
	if lit != nil && lit.Kind() == constant.String {
		return constant.StringVal(lit), true
	}
	return "", false
}

// checkCalls triggers the print-specific checks for calls that invoke a print
// function.
func checkCalls(pass *analysis.Pass, res *Result) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.File)(nil),
		(*ast.CallExpr)(nil),
	}

	var fileVersion string // for selectively suppressing checks; "" if unknown.
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.File:
			fileVersion = versions.Lang(versions.FileVersion(pass.TypesInfo, n))

		case *ast.CallExpr:
			if callee := typeutil.Callee(pass.TypesInfo, n); callee != nil {
				kind := callKind(pass, callee, res)
				switch kind {
				case KindPrintf, KindErrorf:
					checkPrintf(pass, fileVersion, kind, n, fullname(callee))
				case KindPrint:
					checkPrint(pass, n, fullname(callee))
				}
			}
		}
	})
}

func fullname(obj types.Object) string {
	if fn, ok := obj.(*types.Func); ok {
		return fn.FullName()
	}
	return obj.Name()
}

// callKind returns the symbol of the called function
// and its print/printf kind, if any.
// (The symbol may be a var for an anonymous function.)
// The result is memoized in res.funcs.
func callKind(pass *analysis.Pass, obj types.Object, res *Result) Kind {
	kind, ok := res.funcs[obj]
	if !ok {
		// cache miss
		_, ok := isPrint[fullname(obj)]
		if !ok {
			// Next look up just "printf", for use with -printf.funcs.
			_, ok = isPrint[strings.ToLower(obj.Name())]
		}
		if ok {
			// well-known printf functions
			if fullname(obj) == "fmt.Errorf" {
				kind = KindErrorf
			} else if strings.HasSuffix(obj.Name(), "f") {
				kind = KindPrintf
			} else {
				kind = KindPrint
			}
		} else {
			// imported wrappers
			// Facts are associated with generic declarations, not instantiations.
			obj = origin(obj)
			var fact isWrapper
			if pass.ImportObjectFact(obj, &fact) {
				kind = fact.Kind
			}
		}
		res.funcs[obj] = kind // cache
	}
	return kind
}

// isFormatter reports whether t could satisfy fmt.Formatter.
// The only interface method to look for is "Format(State, rune)".
func isFormatter(typ types.Type) bool {
	// If the type is an interface, the value it holds might satisfy fmt.Formatter.
	if _, ok := typ.Underlying().(*types.Interface); ok {
		// Don't assume type parameters could be formatters. With the greater
		// expressiveness of constraint interface syntax we expect more type safety
		// when using type parameters.
		if !typeparams.IsTypeParam(typ) {
			return true
		}
	}
	obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "Format")
	fn, ok := obj.(*types.Func)
	if !ok {
		return false
	}
	sig := fn.Type().(*types.Signature)
	return sig.Params().Len() == 2 &&
		sig.Results().Len() == 0 &&
		typesinternal.IsTypeNamed(sig.Params().At(0).Type(), "fmt", "State") &&
		types.Identical(sig.Params().At(1).Type(), types.Typ[types.Rune])
}

// checkPrintf checks a call to a formatted print routine such as Printf.
func checkPrintf(pass *analysis.Pass, fileVersion string, kind Kind, call *ast.CallExpr, name string) {
	idx := formatStringIndex(pass, call)
	if idx < 0 || idx >= len(call.Args) {
		return
	}
	formatArg := call.Args[idx]
	format, ok := stringConstantExpr(pass, formatArg)
	if !ok {
		// Format string argument is non-constant.

		// It is a common mistake to call fmt.Printf(msg) with a
		// non-constant format string and no arguments:
		// if msg contains "%", misformatting occurs.
		// Report the problem and suggest a fix: fmt.Printf("%s", msg).
		//
		// However, as described in golang/go#71485, this analysis can produce a
		// significant number of diagnostics in existing code, and the bugs it
		// finds are sometimes unlikely or inconsequential, and may not be worth
		// fixing for some users. Gating on language version allows us to avoid
		// breaking existing tests and CI scripts.
		if idx == len(call.Args)-1 &&
			fileVersion != "" && // fail open
			versions.AtLeast(fileVersion, versions.Go1_24) {

			pass.Report(analysis.Diagnostic{
				Pos: formatArg.Pos(),
				End: formatArg.End(),
				Message: fmt.Sprintf("non-constant format string in call to %s",
					name),
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: `Insert "%s" format string`,
					TextEdits: []analysis.TextEdit{{
						Pos:     formatArg.Pos(),
						End:     formatArg.Pos(),
						NewText: []byte(`"%s", `),
					}},
				}},
			})
		}
		return
	}

	firstArg := idx + 1 // Arguments are immediately after format string.
	if !strings.Contains(format, "%") {
		if len(call.Args) > firstArg {
			pass.ReportRangef(call.Args[firstArg], "%s call has arguments but no formatting directives", name)
		}
		return
	}

	// Pass the string constant value so
	// fmt.Sprintf("%"+("s"), "hi", 3) can be reported as
	// "fmt.Sprintf call needs 1 arg but has 2 args".
	operations, err := fmtstr.Parse(format, idx)
	if err != nil {
		// All error messages are in predicate form ("call has a problem")
		// so that they may be affixed into a subject ("log.Printf ").
		pass.ReportRangef(formatArg, "%s %s", name, err)
		return
	}

	// index of the highest used index.
	maxArgIndex := firstArg - 1
	anyIndex := false
	// Check formats against args.
	for _, op := range operations {
		if op.Prec.Index != -1 ||
			op.Width.Index != -1 ||
			op.Verb.Index != -1 {
			anyIndex = true
		}
		rng := opRange(formatArg, op)
		if !okPrintfArg(pass, fileVersion, call, rng, &maxArgIndex, firstArg, name, op) {
			// One error per format is enough.
			return
		}
		if op.Verb.Verb == 'w' {
			switch kind {
			case KindNone, KindPrint, KindPrintf:
				pass.ReportRangef(rng, "%s does not support error-wrapping directive %%w", name)
				return
			}
		}
	}
	// Dotdotdot is hard.
	if call.Ellipsis.IsValid() && maxArgIndex >= len(call.Args)-2 {
		return
	}
	// If any formats are indexed, extra arguments are ignored.
	if anyIndex {
		return
	}
	// There should be no leftover arguments.
	if maxArgIndex+1 < len(call.Args) {
		expect := maxArgIndex + 1 - firstArg
		numArgs := len(call.Args) - firstArg
		pass.ReportRangef(call, "%s call needs %v but has %v", name, count(expect, "arg"), count(numArgs, "arg"))
	}
}

// opRange returns the source range for the specified printf operation,
// such as the position of the %v substring of "...%v...".
func opRange(formatArg ast.Expr, op *fmtstr.Operation) analysis.Range {
	if lit, ok := formatArg.(*ast.BasicLit); ok {
		rng, err := astutil.RangeInStringLiteral(lit, op.Range.Start, op.Range.End)
		if err == nil {
			return rng // position of "%v"
		}
	}
	return formatArg // entire format string
}

// printfArgType encodes the types of expressions a printf verb accepts. It is a bitmask.
type printfArgType int

const (
	argBool printfArgType = 1 << iota
	argByte
	argInt
	argRune
	argString
	argFloat
	argComplex
	argPointer
	argError
	anyType printfArgType = ^0
)

type printVerb struct {
	verb  rune   // User may provide verb through Formatter; could be a rune.
	flags string // known flags are all ASCII
	typ   printfArgType
}

// Common flag sets for printf verbs.
const (
	noFlag       = ""
	numFlag      = " -+.0"
	sharpNumFlag = " -+.0#"
	allFlags     = " -+.0#"
)

// printVerbs identifies which flags are known to printf for each verb.
var printVerbs = []printVerb{
	// '-' is a width modifier, always valid.
	// '.' is a precision for float, max width for strings.
	// '+' is required sign for numbers, Go format for %v.
	// '#' is alternate format for several verbs.
	// ' ' is spacer for numbers
	{'%', noFlag, 0},
	{'b', sharpNumFlag, argInt | argFloat | argComplex | argPointer},
	{'c', "-", argRune | argInt},
	{'d', numFlag, argInt | argPointer},
	{'e', sharpNumFlag, argFloat | argComplex},
	{'E', sharpNumFlag, argFloat | argComplex},
	{'f', sharpNumFlag, argFloat | argComplex},
	{'F', sharpNumFlag, argFloat | argComplex},
	{'g', sharpNumFlag, argFloat | argComplex},
	{'G', sharpNumFlag, argFloat | argComplex},
	{'o', sharpNumFlag, argInt | argPointer},
	{'O', sharpNumFlag, argInt | argPointer},
	{'p', "-#", argPointer},
	{'q', " -+.0#", argRune | argInt | argString}, // note: when analyzing go1.26 code, argInt => argByte
	{'s', " -+.0", argString},
	{'t', "-", argBool},
	{'T', "-", anyType},
	{'U', "-#", argRune | argInt},
	{'v', allFlags, anyType},
	{'w', allFlags, argError},
	{'x', sharpNumFlag, argRune | argInt | argString | argPointer | argFloat | argComplex},
	{'X', sharpNumFlag, argRune | argInt | argString | argPointer | argFloat | argComplex},
}

// okPrintfArg compares the operation to the arguments actually present,
// reporting any discrepancies it can discern, maxArgIndex was the index of the highest used index.
// If the final argument is ellipsissed, there's little it can do for that.
func okPrintfArg(pass *analysis.Pass, fileVersion string, call *ast.CallExpr, rng analysis.Range, maxArgIndex *int, firstArg int, name string, operation *fmtstr.Operation) (ok bool) {
	verb := operation.Verb.Verb
	var v printVerb
	found := false
	// Linear scan is fast enough for a small list.
	for _, v = range printVerbs {
		if v.verb == verb {
			found = true
			break
		}
	}

	// When analyzing go1.26 code, rune and byte are the only %q integers (#72850).
	if verb == 'q' &&
		fileVersion != "" && // fail open
		versions.AtLeast(fileVersion, versions.Go1_26) {
		v.typ = argRune | argByte | argString
	}

	// Could verb's arg implement fmt.Formatter?
	// Skip check for the %w verb, which requires an error.
	formatter := false
	if v.typ != argError && operation.Verb.ArgIndex < len(call.Args) {
		if tv, ok := pass.TypesInfo.Types[call.Args[operation.Verb.ArgIndex]]; ok {
			formatter = isFormatter(tv.Type)
		}
	}

	if !formatter {
		if !found {
			pass.ReportRangef(rng, "%s format %s has unknown verb %c", name, operation.Text, verb)
			return false
		}
		for _, flag := range operation.Flags {
			// TODO: Disable complaint about '0' for Go 1.10. To be fixed properly in 1.11.
			// See issues 23598 and 23605.
			if flag == '0' {
				continue
			}
			if !strings.ContainsRune(v.flags, rune(flag)) {
				pass.ReportRangef(rng, "%s format %s has unrecognized flag %c", name, operation.Text, flag)
				return false
			}
		}
	}

	var argIndexes []int
	// First check for *.
	if operation.Width.Dynamic != -1 {
		argIndexes = append(argIndexes, operation.Width.Dynamic)
	}
	if operation.Prec.Dynamic != -1 {
		argIndexes = append(argIndexes, operation.Prec.Dynamic)
	}
	// If len(argIndexes)>0, we have something like %.*s and all
	// indexes in argIndexes must be an integer.
	for _, argIndex := range argIndexes {
		if !argCanBeChecked(pass, call, rng, argIndex, firstArg, operation, name) {
			return
		}
		arg := call.Args[argIndex]
		if reason, ok := matchArgType(pass, argInt, arg); !ok {
			details := ""
			if reason != "" {
				details = " (" + reason + ")"
			}
			pass.ReportRangef(rng, "%s format %s uses non-int %s%s as argument of *", name, operation.Text, astutil.Format(pass.Fset, arg), details)
			return false
		}
	}

	// Collect to update maxArgNum in one loop.
	if operation.Verb.ArgIndex != -1 && verb != '%' {
		argIndexes = append(argIndexes, operation.Verb.ArgIndex)
	}
	for _, index := range argIndexes {
		*maxArgIndex = max(*maxArgIndex, index)
	}

	// Special case for '%', go will print "fmt.Printf("%10.2%%dhello", 4)"
	// as "%4hello", discard any runes between the two '%'s, and treat the verb '%'
	// as an ordinary rune, so early return to skip the type check.
	if verb == '%' || formatter {
		return true
	}

	// Now check verb's type.
	verbArgIndex := operation.Verb.ArgIndex
	if !argCanBeChecked(pass, call, rng, verbArgIndex, firstArg, operation, name) {
		return false
	}
	arg := call.Args[verbArgIndex]
	if isFunctionValue(pass, arg) && verb != 'p' && verb != 'T' {
		pass.ReportRangef(rng, "%s format %s arg %s is a func value, not called", name, operation.Text, astutil.Format(pass.Fset, arg))
		return false
	}
	if reason, ok := matchArgType(pass, v.typ, arg); !ok {
		typeString := ""
		if typ := pass.TypesInfo.Types[arg].Type; typ != nil {
			typeString = typ.String()
		}
		details := ""
		if reason != "" {
			details = " (" + reason + ")"
		}
		pass.ReportRangef(rng, "%s format %s has arg %s of wrong type %s%s", name, operation.Text, astutil.Format(pass.Fset, arg), typeString, details)
		return false
	}
	// Detect recursive formatting via value's String/Error methods.
	// The '#' flag suppresses the methods, except with %x, %X, and %q.
	if v.typ&argString != 0 && v.verb != 'T' && (!strings.Contains(operation.Flags, "#") || strings.ContainsRune("qxX", v.verb)) {
		if methodName, ok := recursiveStringer(pass, arg); ok {
			pass.ReportRangef(rng, "%s format %s with arg %s causes recursive %s method call", name, operation.Text, astutil.Format(pass.Fset, arg), methodName)
			return false
		}
	}
	return true
}

// recursiveStringer reports whether the argument e is a potential
// recursive call to stringer or is an error, such as t and &t in these examples:
//
//	func (t *T) String() string { printf("%s",  t) }
//	func (t  T) Error() string { printf("%s",  t) }
//	func (t  T) String() string { printf("%s", &t) }
func recursiveStringer(pass *analysis.Pass, e ast.Expr) (string, bool) {
	typ := pass.TypesInfo.Types[e].Type

	// It's unlikely to be a recursive stringer if it has a Format method.
	if isFormatter(typ) {
		return "", false
	}

	// Does e allow e.String() or e.Error()?
	strObj, _, _ := types.LookupFieldOrMethod(typ, false, pass.Pkg, "String")
	strMethod, strOk := strObj.(*types.Func)
	errObj, _, _ := types.LookupFieldOrMethod(typ, false, pass.Pkg, "Error")
	errMethod, errOk := errObj.(*types.Func)
	if !strOk && !errOk {
		return "", false
	}

	// inScope returns true if e is in the scope of f.
	inScope := func(e ast.Expr, f *types.Func) bool {
		return f.Scope() != nil && f.Scope().Contains(e.Pos())
	}

	// Is the expression e within the body of that String or Error method?
	var method *types.Func
	if strOk && strMethod.Pkg() == pass.Pkg && inScope(e, strMethod) {
		method = strMethod
	} else if errOk && errMethod.Pkg() == pass.Pkg && inScope(e, errMethod) {
		method = errMethod
	} else {
		return "", false
	}

	sig := method.Type().(*types.Signature)
	if !isStringer(sig) {
		return "", false
	}

	// Is it the receiver r, or &r?
	if u, ok := e.(*ast.UnaryExpr); ok && u.Op == token.AND {
		e = u.X // strip off & from &r
	}
	if id, ok := e.(*ast.Ident); ok {
		if pass.TypesInfo.Uses[id] == sig.Recv() {
			return method.FullName(), true
		}
	}
	return "", false
}

// isStringer reports whether the method signature matches the String() definition in fmt.Stringer.
func isStringer(sig *types.Signature) bool {
	return sig.Params().Len() == 0 &&
		sig.Results().Len() == 1 &&
		sig.Results().At(0).Type() == types.Typ[types.String]
}

// isFunctionValue reports whether the expression is a function as opposed to a function call.
// It is almost always a mistake to print a function value.
func isFunctionValue(pass *analysis.Pass, e ast.Expr) bool {
	if typ := pass.TypesInfo.Types[e].Type; typ != nil {
		// Don't call Underlying: a named func type with a String method is ok.
		// TODO(adonovan): it would be more precise to check isStringer.
		_, ok := typ.(*types.Signature)
		return ok
	}
	return false
}

// argCanBeChecked reports whether the specified argument is statically present;
// it may be beyond the list of arguments or in a terminal slice... argument, which
// means we can't see it.
func argCanBeChecked(pass *analysis.Pass, call *ast.CallExpr, rng analysis.Range, argIndex, firstArg int, operation *fmtstr.Operation, name string) bool {
	if argIndex <= 0 {
		// Shouldn't happen, so catch it with prejudice.
		panic("negative argIndex")
	}
	if argIndex < len(call.Args)-1 {
		return true // Always OK.
	}
	if call.Ellipsis.IsValid() {
		return false // We just can't tell; there could be many more arguments.
	}
	if argIndex < len(call.Args) {
		return true
	}
	// There are bad indexes in the format or there are fewer arguments than the format needs.
	// This is the argument number relative to the format: Printf("%s", "hi") will give 1 for the "hi".
	arg := argIndex - firstArg + 1 // People think of arguments as 1-indexed.
	pass.ReportRangef(rng, "%s format %s reads arg #%d, but call has %v", name, operation.Text, arg, count(len(call.Args)-firstArg, "arg"))
	return false
}

// printFormatRE is the regexp we match and report as a possible format string
// in the first argument to unformatted prints like fmt.Print.
// We exclude the space flag, so that printing a string like "x % y" is not reported as a format.
var printFormatRE = regexp.MustCompile(`%` + flagsRE + numOptRE + `\.?` + numOptRE + indexOptRE + verbRE)

const (
	flagsRE    = `[+\-#]*`
	indexOptRE = `(\[[0-9]+\])?`
	numOptRE   = `([0-9]+|` + indexOptRE + `\*)?`
	verbRE     = `[bcdefgopqstvxEFGTUX]`
)

// checkPrint checks a call to an unformatted print routine such as Println.
func checkPrint(pass *analysis.Pass, call *ast.CallExpr, name string) {
	firstArg := 0
	typ := pass.TypesInfo.Types[call.Fun].Type
	if typ == nil {
		// Skip checking functions with unknown type.
		return
	}
	if sig, ok := typ.Underlying().(*types.Signature); ok {
		if !sig.Variadic() {
			// Skip checking non-variadic functions.
			return
		}
		params := sig.Params()
		firstArg = params.Len() - 1

		typ := params.At(firstArg).Type()
		typ = typ.(*types.Slice).Elem()
		it, ok := types.Unalias(typ).(*types.Interface)
		if !ok || !it.Empty() {
			// Skip variadic functions accepting non-interface{} args.
			return
		}
	}
	args := call.Args
	if len(args) <= firstArg {
		// Skip calls without variadic args.
		return
	}
	args = args[firstArg:]

	if firstArg == 0 {
		if sel, ok := call.Args[0].(*ast.SelectorExpr); ok {
			if x, ok := sel.X.(*ast.Ident); ok {
				if x.Name == "os" && strings.HasPrefix(sel.Sel.Name, "Std") {
					pass.ReportRangef(call, "%s does not take io.Writer but has first arg %s", name, astutil.Format(pass.Fset, call.Args[0]))
				}
			}
		}
	}

	arg := args[0]
	if s, ok := stringConstantExpr(pass, arg); ok {
		// Ignore trailing % character
		// The % in "abc 0.0%" couldn't be a formatting directive.
		s = strings.TrimSuffix(s, "%")
		if strings.Contains(s, "%") {
			for _, m := range printFormatRE.FindAllString(s, -1) {
				// Allow %XX where XX are hex digits,
				// as this is common in URLs.
				if len(m) >= 3 && isHex(m[1]) && isHex(m[2]) {
					continue
				}
				pass.ReportRangef(call, "%s call has possible Printf formatting directive %s", name, m)
				break // report only the first one
			}
		}
	}
	if strings.HasSuffix(name, "ln") {
		// The last item, if a string, should not have a newline.
		arg = args[len(args)-1]
		if s, ok := stringConstantExpr(pass, arg); ok {
			if strings.HasSuffix(s, "\n") {
				pass.ReportRangef(call, "%s arg list ends with redundant newline", name)
			}
		}
	}
	for _, arg := range args {
		if isFunctionValue(pass, arg) {
			pass.ReportRangef(call, "%s arg %s is a func value, not called", name, astutil.Format(pass.Fset, arg))
		}
		if methodName, ok := recursiveStringer(pass, arg); ok {
			pass.ReportRangef(call, "%s arg %s causes recursive call to %s method", name, astutil.Format(pass.Fset, arg), methodName)
		}
	}
}

// count(n, what) returns "1 what" or "N whats"
// (assuming the plural of what is whats).
func count(n int, what string) string {
	if n == 1 {
		return "1 " + what
	}
	return fmt.Sprintf("%d %ss", n, what)
}

// stringSet is a set-of-nonempty-strings-valued flag.
// Note: elements without a '.' get lower-cased.
type stringSet map[string]bool

func (ss stringSet) String() string {
	var list []string
	for name := range ss {
		list = append(list, name)
	}
	sort.Strings(list)
	return strings.Join(list, ",")
}

func (ss stringSet) Set(flag string) error {
	for name := range strings.SplitSeq(flag, ",") {
		if len(name) == 0 {
			return fmt.Errorf("empty string")
		}
		if !strings.Contains(name, ".") {
			name = strings.ToLower(name)
		}
		ss[name] = true
	}
	return nil
}

// isHex reports whether b is a hex digit.
func isHex(b byte) bool {
	return '0' <= b && b <= '9' ||
		'A' <= b && b <= 'F' ||
		'a' <= b && b <= 'f'
}


================================================
FILE: go/analysis/passes/printf/printf_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package printf_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	printf.Analyzer.Flags.Set("funcs", "Warn,Warnf")

	analysistest.Run(t, testdata, printf.Analyzer,
		"a", "b", "nofmt", "nonconst", "typeparams", "issue68744", "issue70572", "issue72850", "issue76616")
}

func TestNonConstantFmtString_Go123(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)

	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "nonconst_go123.txtar"))
	analysistest.RunWithSuggestedFixes(t, dir, printf.Analyzer, "example.com/nonconst")
}

func TestNonConstantFmtString_Go124(t *testing.T) {
	testenv.NeedsGo1Point(t, 24)

	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "nonconst_go124.txtar"))
	analysistest.RunWithSuggestedFixes(t, dir, printf.Analyzer, "example.com/nonconst")
}


================================================
FILE: go/analysis/passes/printf/testdata/nonconst_go123.txtar
================================================
This test checks for the correct suppression (or activation) of the
non-constant format string check (golang/go#60529), in a go1.23 module.

See golang/go#71485 for details.

-- go.mod --
module example.com/nonconst

go 1.23

-- nonconst.go --
package nonconst

import (
	"fmt"
	"log"
	"os"
)

func _(s string) {
	fmt.Printf(s)
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, s)
	log.Printf(s)
}

-- nonconst_go124.go --
//go:build go1.24
package nonconst

import (
	"fmt"
	"log"
	"os"
)

// With Go 1.24, the analyzer should be activated, as this is a go1.24 file.
func _(s string) {
	fmt.Printf(s) // want `non-constant format string in call to fmt.Printf`
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, s) // want `non-constant format string in call to fmt.Fprintf`
	log.Printf(s)             // want `non-constant format string in call to log.Printf`
}

-- nonconst_go124.go.golden --
//go:build go1.24
package nonconst

import (
	"fmt"
	"log"
	"os"
)

// With Go 1.24, the analyzer should be activated, as this is a go1.24 file.
func _(s string) {
	fmt.Printf("%s", s) // want `non-constant format string in call to fmt.Printf`
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, "%s", s) // want `non-constant format string in call to fmt.Fprintf`
	log.Printf("%s", s)             // want `non-constant format string in call to log.Printf`
}


================================================
FILE: go/analysis/passes/printf/testdata/nonconst_go124.txtar
================================================
This test checks for the correct suppression (or activation) of the
non-constant format string check (golang/go#60529), in a go1.24 module.

See golang/go#71485 for details.

-- go.mod --
module example.com/nonconst

go 1.24

-- nonconst.go --
package nonconst

import (
	"fmt"
	"log"
	"os"
)

func _(s string) {
	fmt.Printf(s) // want `non-constant format string in call to fmt.Printf`
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, s) // want `non-constant format string in call to fmt.Fprintf`
	log.Printf(s)             // want `non-constant format string in call to log.Printf`
}

-- nonconst.go.golden --
package nonconst

import (
	"fmt"
	"log"
	"os"
)

func _(s string) {
	fmt.Printf("%s", s) // want `non-constant format string in call to fmt.Printf`
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, "%s", s) // want `non-constant format string in call to fmt.Fprintf`
	log.Printf("%s", s)             // want `non-constant format string in call to log.Printf`
}

-- nonconst_go123.go --
//go:build go1.23
package nonconst

import (
	"fmt"
	"log"
	"os"
)

// The analyzer should be silent, as this is a go1.23 file.
func _(s string) {
	fmt.Printf(s)
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, s)
	log.Printf(s)
}


================================================
FILE: go/analysis/passes/printf/testdata/src/a/a.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the printf checker.

package a

import (
	"fmt"
	logpkg "log" // renamed to make it harder to see
	"math"
	"os"
	"testing"
	"unsafe" // just for test case printing unsafe.Pointer

	// For testing printf-like functions from external package.
	// "github.com/foobar/externalprintf"
	"b"
)

func UnsafePointerPrintfTest() {
	var up unsafe.Pointer
	fmt.Printf("%p, %x %X", up, up, up)
}

// Error methods that do not satisfy the Error interface and should be checked.
type errorTest1 int

func (errorTest1) Error(...interface{}) string {
	return "hi"
}

type errorTest2 int // Analogous to testing's *T type.
func (errorTest2) Error(...interface{}) {
}

type errorTest3 int

func (errorTest3) Error() { // No return value.
}

type errorTest4 int

func (errorTest4) Error() int { // Different return type.
	return 3
}

type errorTest5 int

func (errorTest5) error() { // niladic; don't complain if no args (was bug)
}

type errorTestOK int

func (errorTestOK) Error() string { return "" }

// This function never executes, but it serves as a simple test for the program.
// Test with make test.
func PrintfTests() {
	var b bool
	var i int
	var r rune
	var s string
	var x float64
	var p *int
	var imap map[int]int
	var fslice []float64
	var c complex64
	var err error
	// Some good format/argtypes
	fmt.Printf("")
	fmt.Printf("%b %b %b", 3, i, x)
	fmt.Printf("%c %c %c %c", 3, i, 'x', r)
	fmt.Printf("%d %d %d", 3, i, imap)
	fmt.Printf("%e %e %e %e", 3e9, x, fslice, c)
	fmt.Printf("%E %E %E %E", 3e9, x, fslice, c)
	fmt.Printf("%f %f %f %f", 3e9, x, fslice, c)
	fmt.Printf("%F %F %F %F", 3e9, x, fslice, c)
	fmt.Printf("%g %g %g %g", 3e9, x, fslice, c)
	fmt.Printf("%G %G %G %G", 3e9, x, fslice, c)
	fmt.Printf("%b %b %b %b", 3e9, x, fslice, c)
	fmt.Printf("%o %o", 3, i)
	fmt.Printf("%O %O", 3, i)
	fmt.Printf("%p", p)
	fmt.Printf("%q %q %q", byte(i), 'x', r)
	fmt.Printf("%s %s %s", "hi", s, []byte{65})
	fmt.Printf("%t %t", true, b)
	fmt.Printf("%T %T", 3, i)
	fmt.Printf("%U %U", 3, i)
	fmt.Printf("%v %v", 3, i)
	fmt.Printf("%x %x %x %x %x %x %x", 3, i, "hi", s, x, c, fslice)
	fmt.Printf("%X %X %X %X %X %X %X", 3, i, "hi", s, x, c, fslice)
	fmt.Printf("%.*s %d %g", 3, "hi", 23, 2.3)
	fmt.Printf("%s", &stringerv)
	fmt.Printf("%v", &stringerv)
	fmt.Printf("%T", &stringerv)
	fmt.Printf("%s", &embeddedStringerv)
	fmt.Printf("%v", &embeddedStringerv)
	fmt.Printf("%T", &embeddedStringerv)
	fmt.Printf("%v", notstringerv)
	fmt.Printf("%T", notstringerv)
	fmt.Printf("%q", stringerarrayv)
	fmt.Printf("%v", stringerarrayv)
	fmt.Printf("%s", stringerarrayv)
	fmt.Printf("%v", notstringerarrayv)
	fmt.Printf("%T", notstringerarrayv)
	fmt.Printf("%d", new(fmt.Formatter))
	fmt.Printf("%*%", 2)                              // Ridiculous but allowed.
	fmt.Printf("%s", interface{}(nil))                // Nothing useful we can say.
	fmt.Printf("%a", interface{}(new(BoolFormatter))) // Could be a fmt.Formatter.

	fmt.Printf("%g", 1+2i)
	fmt.Printf("%#e %#E %#f %#F %#g %#G", 1.2, 1.2, 1.2, 1.2, 1.2, 1.2) // OK since Go 1.9
	// Some bad format/argTypes
	fmt.Printf("%b", "hi")                      // want "fmt.Printf format %b has arg \x22hi\x22 of wrong type string"
	fmt.Printf("%t", c)                         // want "fmt.Printf format %t has arg c of wrong type complex64"
	fmt.Printf("%t", 1+2i)                      // want `fmt.Printf format %t has arg 1 \+ 2i of wrong type complex128`
	fmt.Printf("%c", 2.3)                       // want "fmt.Printf format %c has arg 2.3 of wrong type float64"
	fmt.Printf("%d", 2.3)                       // want "fmt.Printf format %d has arg 2.3 of wrong type float64"
	fmt.Printf("%e", "hi")                      // want `fmt.Printf format %e has arg "hi" of wrong type string`
	fmt.Printf("%E", true)                      // want "fmt.Printf format %E has arg true of wrong type bool"
	fmt.Printf("%f", "hi")                      // want "fmt.Printf format %f has arg \x22hi\x22 of wrong type string"
	fmt.Printf("%F", 'x')                       // want "fmt.Printf format %F has arg 'x' of wrong type rune"
	fmt.Printf("%g", "hi")                      // want `fmt.Printf format %g has arg "hi" of wrong type string`
	fmt.Printf("%g", imap)                      // want `fmt.Printf format %g has arg imap of wrong type map\[int\]int`
	fmt.Printf("%G", i)                         // want "fmt.Printf format %G has arg i of wrong type int"
	fmt.Printf("%o", x)                         // want "fmt.Printf format %o has arg x of wrong type float64"
	fmt.Printf("%O", x)                         // want "fmt.Printf format %O has arg x of wrong type float64"
	fmt.Printf("%p", nil)                       // want "fmt.Printf format %p has arg nil of wrong type untyped nil"
	fmt.Printf("%p", 23)                        // want "fmt.Printf format %p has arg 23 of wrong type int"
	fmt.Printf("%q", x)                         // want "fmt.Printf format %q has arg x of wrong type float64"
	fmt.Printf("%s", b)                         // want "fmt.Printf format %s has arg b of wrong type bool"
	fmt.Printf("%s", byte(65))                  // want `fmt.Printf format %s has arg byte\(65\) of wrong type byte`
	fmt.Printf("%t", 23)                        // want "fmt.Printf format %t has arg 23 of wrong type int"
	fmt.Printf("%U", x)                         // want "fmt.Printf format %U has arg x of wrong type float64"
	fmt.Printf("%x", nil)                       // want "fmt.Printf format %x has arg nil of wrong type untyped nil"
	fmt.Printf("%s", stringerv)                 // want "fmt.Printf format %s has arg stringerv of wrong type a.ptrStringer"
	fmt.Printf("%t", stringerv)                 // want "fmt.Printf format %t has arg stringerv of wrong type a.ptrStringer"
	fmt.Printf("%s", embeddedStringerv)         // want "fmt.Printf format %s has arg embeddedStringerv of wrong type a.embeddedStringer"
	fmt.Printf("%t", embeddedStringerv)         // want "fmt.Printf format %t has arg embeddedStringerv of wrong type a.embeddedStringer"
	fmt.Printf("%q", notstringerv)              // want "fmt.Printf format %q has arg notstringerv of wrong type a.notstringer"
	fmt.Printf("%t", notstringerv)              // want "fmt.Printf format %t has arg notstringerv of wrong type a.notstringer"
	fmt.Printf("%t", stringerarrayv)            // want "fmt.Printf format %t has arg stringerarrayv of wrong type a.stringerarray"
	fmt.Printf("%t", notstringerarrayv)         // want "fmt.Printf format %t has arg notstringerarrayv of wrong type a.notstringerarray"
	fmt.Printf("%q", notstringerarrayv)         // want "fmt.Printf format %q has arg notstringerarrayv of wrong type a.notstringerarray"
	fmt.Printf("%d", BoolFormatter(true))       // want `fmt.Printf format %d has arg BoolFormatter\(true\) of wrong type a.BoolFormatter`
	fmt.Printf("%z", FormatterVal(true))        // correct (the type is responsible for formatting)
	fmt.Printf("%d", FormatterVal(true))        // correct (the type is responsible for formatting)
	fmt.Printf("%s", nonemptyinterface)         // correct (the type is responsible for formatting)
	fmt.Printf("%.*s %d %6g", 3, "hi", 23, 'x') // want "fmt.Printf format %6g has arg 'x' of wrong type rune"
	fmt.Println()                               // not an error
	fmt.Println("%s", "hi")                     // want "fmt.Println call has possible Printf formatting directive %s"
	fmt.Println("%v", "hi")                     // want "fmt.Println call has possible Printf formatting directive %v"
	fmt.Println("%T", "hi")                     // want "fmt.Println call has possible Printf formatting directive %T"
	fmt.Println("%s"+" there", "hi")            // want "fmt.Println call has possible Printf formatting directive %s"
	fmt.Println("http://foo.com?q%2Fabc")       // no diagnostic: %XX is excepted
	fmt.Println("http://foo.com?q%2Fabc-%s")    // want"fmt.Println call has possible Printf formatting directive %s"
	fmt.Println("0.0%")                         // correct (trailing % couldn't be a formatting directive)
	fmt.Printf("%s", "hi", 3)                   // want "fmt.Printf call needs 1 arg but has 2 args"
	_ = fmt.Sprintf("%"+("s"), "hi", 3)         // want "fmt.Sprintf call needs 1 arg but has 2 args"
	fmt.Printf("%s%%%d", "hi", 3)               // correct
	fmt.Printf("%08s", "woo")                   // correct
	fmt.Printf("% 8s", "woo")                   // correct
	fmt.Printf("%.*d", 3, 3)                    // correct
	fmt.Printf("%.*d x", 3, 3, 3, 3)            // want "fmt.Printf call needs 2 args but has 4 args"
	fmt.Printf("%.*d x", "hi", 3)               // want `fmt.Printf format %.*d uses non-int "hi" as argument of \*`
	fmt.Printf("%.*d x", i, 3)                  // correct
	fmt.Printf("%.*d x", s, 3)                  // want `fmt.Printf format %.\*d uses non-int s as argument of \*`
	fmt.Printf("%*% x", 0.22)                   // want `fmt.Printf format %\*% uses non-int 0.22 as argument of \*`
	fmt.Printf("%q %q", multi()...)             // ok
	fmt.Printf("%#q", `blah`)                   // ok
	fmt.Printf("%#b", 3)                        // ok
	fmt.Printf("%q", 3)                         // ok before go1.26 (#72850)

	// printf("now is the time", "buddy")          // no error "a.printf call has arguments but no formatting directives"
	Printf("now is the time", "buddy") // want "a.Printf call has arguments but no formatting directives"
	Printf("hi")                       // ok
	const format = "%s %s\n"
	Printf(format, "hi", "there")
	Printf(format, "hi")              // want "a.Printf format %s reads arg #2, but call has 1 arg$"
	Printf("%s %d %.3v %q", "str", 4) // want "a.Printf format %.3v reads arg #3, but call has 2 args"
	f := new(ptrStringer)
	f.Warn(0, "%s", "hello", 3)           // want `\(\*a.ptrStringer\).Warn call has possible Printf formatting directive %s`
	f.Warnf(0, "%s", "hello", 3)          // want `\(\*a.ptrStringer\).Warnf call needs 1 arg but has 2 args`
	f.Warnf(0, "%r", "hello")             // want `\(\*a.ptrStringer\).Warnf format %r has unknown verb r`
	f.Warnf(0, "%#s", "hello")            // want `\(\*a.ptrStringer\).Warnf format %#s has unrecognized flag #`
	f.Warn2(0, "%s", "hello", 3)          // want `\(\*a.ptrStringer\).Warn2 call has possible Printf formatting directive %s`
	f.Warnf2(0, "%s", "hello", 3)         // want `\(\*a.ptrStringer\).Warnf2 call needs 1 arg but has 2 args`
	f.Warnf2(0, "%r", "hello")            // want `\(\*a.ptrStringer\).Warnf2 format %r has unknown verb r`
	f.Warnf2(0, "%#s", "hello")           // want `\(\*a.ptrStringer\).Warnf2 format %#s has unrecognized flag #`
	f.Wrap(0, "%s", "hello", 3)           // want `\(\*a.ptrStringer\).Wrap call has possible Printf formatting directive %s`
	f.Wrapf(0, "%s", "hello", 3)          // want `\(\*a.ptrStringer\).Wrapf call needs 1 arg but has 2 args`
	f.Wrapf(0, "%r", "hello")             // want `\(\*a.ptrStringer\).Wrapf format %r has unknown verb r`
	f.Wrapf(0, "%#s", "hello")            // want `\(\*a.ptrStringer\).Wrapf format %#s has unrecognized flag #`
	f.Wrap2(0, "%s", "hello", 3)          // want `\(\*a.ptrStringer\).Wrap2 call has possible Printf formatting directive %s`
	f.Wrapf2(0, "%s", "hello", 3)         // want `\(\*a.ptrStringer\).Wrapf2 call needs 1 arg but has 2 args`
	f.Wrapf2(0, "%r", "hello")            // want `\(\*a.ptrStringer\).Wrapf2 format %r has unknown verb r`
	f.Wrapf2(0, "%#s", "hello")           // want `\(\*a.ptrStringer\).Wrapf2 format %#s has unrecognized flag #`
	fmt.Printf("%#s", FormatterVal(true)) // correct (the type is responsible for formatting)
	Printf("d%", 2)                       // want "a.Printf format % is missing verb at end of string"
	Printf("%d", percentDV)
	Printf("%d", &percentDV)
	Printf("%d", notPercentDV)  // want "a.Printf format %d has arg notPercentDV of wrong type a.notPercentDStruct"
	Printf("%d", &notPercentDV) // want `a.Printf format %d has arg &notPercentDV of wrong type \*a.notPercentDStruct`
	Printf("%p", &notPercentDV) // Works regardless: we print it as a pointer.
	Printf("%q", &percentDV)    // want `a.Printf format %q has arg &percentDV of wrong type \*a.percentDStruct`
	Printf("%s", percentSV)
	Printf("%s", &percentSV)
	// Good argument reorderings.
	Printf("%[1]d", 3)
	Printf("%[1]*d", 3, 1)
	Printf("%[2]*[1]d", 1, 3)
	Printf("%[2]*.[1]*[3]d", 2, 3, 4)
	fmt.Fprintf(os.Stderr, "%[2]*.[1]*[3]d", 2, 3, 4) // Use Fprintf to make sure we count arguments correctly.
	// Bad argument reorderings.
	Printf("%[xd", 3)                      // want `a.Printf format %\[xd is missing closing \]`
	Printf("%[x]d x", 3)                   // want `a.Printf format has invalid argument index \[x\]`
	Printf("%[3]*s x", "hi", 2)            // want `a.Printf format %\[3]\*s reads arg #3, but call has 2 args`
	_ = fmt.Sprintf("%[3]d x", 2)          // want `fmt.Sprintf format %\[3]d reads arg #3, but call has 1 arg`
	Printf("%[2]*.[1]*[3]d x", 2, "hi", 4) // want `a.Printf format %\[2]\*\.\[1\]\*\[3\]d uses non-int \x22hi\x22 as argument of \*`
	Printf("%[0]s x", "arg1")              // want `a.Printf format has invalid argument index \[0\]`
	Printf("%[0]d x", 1)                   // want `a.Printf format has invalid argument index \[0\]`
	Printf("%[3]*.[2*[1]f", 1, 2, 3)       // want `a.Printf format has invalid argument index \[2\*\[1\]`
	// Something that satisfies the error interface.
	var e error
	fmt.Println(e.Error()) // ok
	// Something that looks like an error interface but isn't, such as the (*T).Error method
	// in the testing package.
	var et1 *testing.T
	et1.Error()         // ok
	et1.Error("hi")     // ok
	et1.Error("%d", 3)  // want `\(\*testing.common\).Error call has possible Printf formatting directive %d`
	et1.Errorf("%s", 1) // want `\(\*testing.common\).Errorf format %s has arg 1 of wrong type int`
	var et3 errorTest3
	et3.Error() // ok, not an error method.
	var et4 errorTest4
	et4.Error() // ok, not an error method.
	var et5 errorTest5
	et5.error() // ok, not an error method.
	// Interfaces can be used with any verb.
	var iface interface {
		ToTheMadness() bool // Method ToTheMadness usually returns false
	}
	fmt.Printf("%f", iface) // ok: fmt treats interfaces as transparent and iface may well have a float concrete type
	// Can't print a function.
	Printf("%d", someFunction) // want "a.Printf format %d arg someFunction is a func value, not called"
	Printf("%v", someFunction) // want "a.Printf format %v arg someFunction is a func value, not called"
	Println(someFunction)      // want "a.Println arg someFunction is a func value, not called"
	Printf("%p", someFunction) // ok: maybe someone wants to see the pointer
	Printf("%T", someFunction) // ok: maybe someone wants to see the type
	// Bug: used to recur forever.
	Printf("%p %x", recursiveStructV, recursiveStructV.next)
	Printf("%p %x", recursiveStruct1V, recursiveStruct1V.next) // want `a.Printf format %x has arg recursiveStruct1V\.next of wrong type \*a\.RecursiveStruct2`
	Printf("%p %x", recursiveSliceV, recursiveSliceV)
	Printf("%p %x", recursiveMapV, recursiveMapV)
	// Special handling for Log.
	math.Log(3) // OK
	var t *testing.T
	t.Log("%d", 3) // want `\(\*testing.common\).Log call has possible Printf formatting directive %d`
	t.Logf("%d", 3)
	t.Logf("%d", "hi") // want `\(\*testing.common\).Logf format %d has arg "hi" of wrong type string`

	Errorf(1, "%d", 3)    // OK
	Errorf(1, "%d", "hi") // want `a.Errorf format %d has arg "hi" of wrong type string`

	// Multiple string arguments before variadic args
	errorf("WARNING", "foobar")            // OK
	errorf("INFO", "s=%s, n=%d", "foo", 1) // OK
	errorf("ERROR", "%d")                  // want "a.errorf format %d reads arg #1, but call has 0 args"

	var tb testing.TB
	tb.Errorf("%s", 1) // want `\(testing.TB\).Errorf format %s has arg 1 of wrong type int`

	// Printf from external package
	// externalprintf.Printf("%d", 42) // OK
	// externalprintf.Printf("foobar") // OK
	// level := 123
	// externalprintf.Logf(level, "%d", 42)                        // OK
	// externalprintf.Errorf(level, level, "foo %q bar", "foobar") // OK
	// externalprintf.Logf(level, "%d")                            // no error "Logf format %d reads arg #1, but call has 0 args"
	// var formatStr = "%s %s"
	// externalprintf.Sprintf(formatStr, "a", "b")     // OK
	// externalprintf.Logf(level, formatStr, "a", "b") // OK

	// user-defined Println-like functions
	ss := &someStruct{}
	ss.Log(someFunction, "foo")          // OK
	ss.Error(someFunction, someFunction) // OK
	ss.Println()                         // OK
	ss.Println(1.234, "foo")             // OK
	ss.Println(1, someFunction)          // no error "Println arg someFunction is a func value, not called"
	ss.log(someFunction)                 // OK
	ss.log(someFunction, "bar", 1.33)    // OK
	ss.log(someFunction, someFunction)   // no error "log arg someFunction is a func value, not called"

	// indexed arguments
	Printf("%d %[3]d %d %[2]d x", 1, 2, 3, 4)             // OK
	Printf("%d %[0]d %d %[2]d x", 1, 2, 3, 4)             // want `a.Printf format has invalid argument index \[0\]`
	Printf("%d %[3]d %d %[-2]d x", 1, 2, 3, 4)            // want `a.Printf format has invalid argument index \[-2\]`
	Printf("%d %[3]d %d %[2234234234234]d x", 1, 2, 3, 4) // want `a.Printf format has invalid argument index \[2234234234234\]`
	Printf("%d %[3]d %-10d %[2]d x", 1, 2, 3)             // want "a.Printf format %-10d reads arg #4, but call has 3 args"
	Printf("%[1][3]d x", 1, 2)                            // want `a.Printf format %\[1\]\[ has unknown verb \[`
	Printf("%[1]d x", 1, 2)                               // OK
	Printf("%d %[3]d %d %[2]d x", 1, 2, 3, 4, 5)          // OK

	// wrote Println but meant Fprintln
	Printf("%p\n", os.Stdout)   // OK
	Println(os.Stdout, "hello") // want "a.Println does not take io.Writer but has first arg os.Stdout"

	Printf(someString(), "hello") // OK

	// Printf wrappers in package log should be detected automatically
	logpkg.Fatal("%d", 1)    // want "log.Fatal call has possible Printf formatting directive %d"
	logpkg.Fatalf("%d", "x") // want `log.Fatalf format %d has arg "x" of wrong type string`
	logpkg.Fatalln("%d", 1)  // want "log.Fatalln call has possible Printf formatting directive %d"
	logpkg.Panic("%d", 1)    // want "log.Panic call has possible Printf formatting directive %d"
	logpkg.Panicf("%d", "x") // want `log.Panicf format %d has arg "x" of wrong type string`
	logpkg.Panicln("%d", 1)  // want "log.Panicln call has possible Printf formatting directive %d"
	logpkg.Print("%d", 1)    // want "log.Print call has possible Printf formatting directive %d"
	logpkg.Printf("%d", "x") // want `log.Printf format %d has arg "x" of wrong type string`
	logpkg.Println("%d", 1)  // want "log.Println call has possible Printf formatting directive %d"

	// Methods too.
	var l *logpkg.Logger
	l.Fatal("%d", 1)    // want `\(\*log.Logger\).Fatal call has possible Printf formatting directive %d`
	l.Fatalf("%d", "x") // want `\(\*log.Logger\).Fatalf format %d has arg "x" of wrong type string`
	l.Fatalln("%d", 1)  // want `\(\*log.Logger\).Fatalln call has possible Printf formatting directive %d`
	l.Panic("%d", 1)    // want `\(\*log.Logger\).Panic call has possible Printf formatting directive %d`
	l.Panicf("%d", "x") // want `\(\*log.Logger\).Panicf format %d has arg "x" of wrong type string`
	l.Panicln("%d", 1)  // want `\(\*log.Logger\).Panicln call has possible Printf formatting directive %d`
	l.Print("%d", 1)    // want `\(\*log.Logger\).Print call has possible Printf formatting directive %d`
	l.Printf("%d", "x") // want `\(\*log.Logger\).Printf format %d has arg "x" of wrong type string`
	l.Println("%d", 1)  // want `\(\*log.Logger\).Println call has possible Printf formatting directive %d`

	// Issue 26486
	dbg("", 1) // no error "call has arguments but no formatting directive"

	// %w
	var errSubset interface {
		Error() string
		A()
	}
	_ = fmt.Errorf("%w", err)               // OK
	_ = fmt.Errorf("%#w", err)              // OK
	_ = fmt.Errorf("%[2]w %[1]s", "x", err) // OK
	_ = fmt.Errorf("%[2]w %[1]s", e, "x")   // want `fmt.Errorf format %\[2\]w has arg "x" of wrong type string`
	_ = fmt.Errorf("%w", "x")               // want `fmt.Errorf format %w has arg "x" of wrong type string`
	_ = fmt.Errorf("%w %w", err, err)       // OK
	_ = fmt.Errorf("%w", interface{}(nil))  // want `fmt.Errorf format %w has arg interface{}\(nil\) of wrong type interface{}`
	_ = fmt.Errorf("%w", errorTestOK(0))    // concrete value implements error
	_ = fmt.Errorf("%w", errSubset)         // interface value implements error
	fmt.Printf("%w", err)                   // want `fmt.Printf does not support error-wrapping directive %w`
	var wt *testing.T
	wt.Errorf("%w", err)          // want `\(\*testing.common\).Errorf does not support error-wrapping directive %w`
	wt.Errorf("%[1][3]d x", 1, 2) // want `\(\*testing.common\).Errorf format %\[1\]\[ has unknown verb \[`
	wt.Errorf("%[1]d x", 1, 2)    // OK
	// Errorf is a printfWrapper, not an errorfWrapper.
	Errorf(0, "%w", err) // want `a.Errorf does not support error-wrapping directive %w`
	// %w should work on fmt.Errorf-based wrappers.
	var es errorfStruct
	var eis errorfIntStruct
	var ess errorfStringStruct
	es.Errorf("%w", err)           // OK
	eis.Errorf(0, "%w", err)       // OK
	ess.Errorf("ERROR", "%w", err) // OK
	fmt.Appendf(nil, "%d", "123")  // want `wrong type`
	fmt.Append(nil, "%d", 123)     // want `fmt.Append call has possible Printf formatting directive %d`

}

func someString() string { return "X" }

type someStruct struct{}

// Log is non-variadic user-define Println-like function.
// Calls to this func must be skipped when checking
// for Println-like arguments.
func (ss *someStruct) Log(f func(), s string) {}

// Error is variadic user-define Println-like function.
// Calls to this func mustn't be checked for Println-like arguments,
// since variadic arguments type isn't interface{}.
func (ss *someStruct) Error(args ...func()) {}

// Println is variadic user-defined Println-like function.
// Calls to this func must be checked for Println-like arguments.
func (ss *someStruct) Println(args ...interface{}) {}

// log is variadic user-defined Println-like function.
// Calls to this func must be checked for Println-like arguments.
func (ss *someStruct) log(f func(), args ...interface{}) {}

// A function we use as a function value; it has no other purpose.
func someFunction() {}

// Printf is used by the test so we must declare it.
func Printf(format string, args ...interface{}) { // want Printf:"printfWrapper"
	fmt.Printf(format, args...)
}

// Println is used by the test so we must declare it.
func Println(args ...interface{}) { // want Println:"printWrapper"
	fmt.Println(args...)
}

// printf is used by the test so we must declare it.
func printf(format string, args ...interface{}) { // want printf:"printfWrapper"
	fmt.Printf(format, args...)
}

// Errorf is used by the test for a case in which the first parameter
// is not a format string.
func Errorf(i int, format string, args ...interface{}) { // want Errorf:"printfWrapper"
	fmt.Sprintf(format, args...)
}

// errorf is used by the test for a case in which the function accepts multiple
// string parameters before variadic arguments
func errorf(level, format string, args ...interface{}) { // want errorf:"printfWrapper"
	fmt.Sprintf(format, args...)
}

type errorfStruct struct{}

// Errorf is used to test %w works on errorf wrappers.
func (errorfStruct) Errorf(format string, args ...interface{}) { // want Errorf:"errorfWrapper"
	_ = fmt.Errorf(format, args...)
}

type errorfStringStruct struct{}

// Errorf is used by the test for a case in which the function accepts multiple
// string parameters before variadic arguments
func (errorfStringStruct) Errorf(level, format string, args ...interface{}) { // want Errorf:"errorfWrapper"
	_ = fmt.Errorf(format, args...)
}

type errorfIntStruct struct{}

// Errorf is used by the test for a case in which the first parameter
// is not a format string.
func (errorfIntStruct) Errorf(i int, format string, args ...interface{}) { // want Errorf:"errorfWrapper"
	_ = fmt.Errorf(format, args...)
}

// multi is used by the test.
func multi() []interface{} {
	panic("don't call - testing only")
}

type stringer int

func (stringer) String() string { return "string" }

type ptrStringer float64

var stringerv ptrStringer

func (*ptrStringer) String() string {
	return "string"
}

func (p *ptrStringer) Warn2(x int, args ...interface{}) string { // want Warn2:"printWrapper"
	return p.Warn(x, args...)
}

func (p *ptrStringer) Warnf2(x int, format string, args ...interface{}) string { // want Warnf2:"printfWrapper"
	return p.Warnf(x, format, args...)
}

// During testing -printf.funcs flag matches Warn.
func (*ptrStringer) Warn(x int, args ...interface{}) string {
	return "warn"
}

// During testing -printf.funcs flag matches Warnf.
func (*ptrStringer) Warnf(x int, format string, args ...interface{}) string {
	return "warnf"
}

func (p *ptrStringer) Wrap2(x int, args ...interface{}) string { // want Wrap2:"printWrapper"
	return p.Wrap(x, args...)
}

func (p *ptrStringer) Wrapf2(x int, format string, args ...interface{}) string { // want Wrapf2:"printfWrapper"
	return p.Wrapf(x, format, args...)
}

func (*ptrStringer) Wrap(x int, args ...interface{}) string { // want Wrap:"printWrapper"
	return fmt.Sprint(args...)
}

func (*ptrStringer) Wrapf(x int, format string, args ...interface{}) string { // want Wrapf:"printfWrapper"
	return fmt.Sprintf(format, args...)
}

func (*ptrStringer) BadWrap(x int, args ...interface{}) string {
	return fmt.Sprint(args) // want "missing ... in args forwarded to print-like function"
}

func (*ptrStringer) BadWrapf(x int, format string, args ...interface{}) string {
	return fmt.Sprintf(format, args) // want "missing ... in args forwarded to printf-like function"
}

func (*ptrStringer) WrapfFalsePositive(x int, arg1 string, arg2 ...interface{}) string {
	return fmt.Sprintf("%s %v", arg1, arg2)
}

type embeddedStringer struct {
	foo string
	ptrStringer
	bar int
}

var embeddedStringerv embeddedStringer

type notstringer struct {
	f float64
}

var notstringerv notstringer

type stringerarray [4]float64

func (stringerarray) String() string {
	return "string"
}

var stringerarrayv stringerarray

type notstringerarray [4]float64

var notstringerarrayv notstringerarray

var nonemptyinterface = interface {
	f()
}(nil)

// A data type we can print with "%d".
type percentDStruct struct {
	a int
	b []byte
	c *float64
}

var percentDV percentDStruct

// A data type we cannot print correctly with "%d".
type notPercentDStruct struct {
	a int
	b []byte
	c bool
}

var notPercentDV notPercentDStruct

// A data type we can print with "%s".
type percentSStruct struct {
	a string
	b []byte
	C stringerarray
}

var percentSV percentSStruct

type recursiveStringer int

func (s recursiveStringer) String() string {
	_ = fmt.Sprintf("%d", s)
	_ = fmt.Sprintf("%#v", s)
	_ = fmt.Sprintf("%v", s)   // want `fmt.Sprintf format %v with arg s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%v", &s)  // want `fmt.Sprintf format %v with arg &s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#x", s)  // want `fmt.Sprintf format %#x with arg s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#x", &s) // want `fmt.Sprintf format %#x with arg &s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#X", s)  // want `fmt.Sprintf format %#X with arg s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#X", &s) // want `fmt.Sprintf format %#X with arg &s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#q", s)  // want `fmt.Sprintf format %#q with arg s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%#q", &s) // want `fmt.Sprintf format %#q with arg &s causes recursive \(a.recursiveStringer\).String method call`
	_ = fmt.Sprintf("%T", s)   // ok; does not recursively call String
	return fmt.Sprintln(s)     // want `fmt.Sprintln arg s causes recursive call to \(a.recursiveStringer\).String method`
}

type recursivePtrStringer int

func (p *recursivePtrStringer) String() string {
	_ = fmt.Sprintf("%v", *p)
	_ = fmt.Sprint(&p)     // ok; prints address
	return fmt.Sprintln(p) // want `fmt.Sprintln arg p causes recursive call to \(\*a.recursivePtrStringer\).String method`
}

type recursiveError int

func (s recursiveError) Error() string {
	_ = fmt.Sprintf("%d", s)
	_ = fmt.Sprintf("%#v", s)
	_ = fmt.Sprintf("%v", s)   // want `fmt.Sprintf format %v with arg s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%v", &s)  // want `fmt.Sprintf format %v with arg &s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#x", s)  // want `fmt.Sprintf format %#x with arg s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#x", &s) // want `fmt.Sprintf format %#x with arg &s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#X", s)  // want `fmt.Sprintf format %#X with arg s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#X", &s) // want `fmt.Sprintf format %#X with arg &s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#q", s)  // want `fmt.Sprintf format %#q with arg s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%#q", &s) // want `fmt.Sprintf format %#q with arg &s causes recursive \(a.recursiveError\).Error method call`
	_ = fmt.Sprintf("%T", s)   // ok; does not recursively call Error
	return fmt.Sprintln(s)     // want `fmt.Sprintln arg s causes recursive call to \(a.recursiveError\).Error method`
}

type recursivePtrError int

func (p *recursivePtrError) Error() string {
	_ = fmt.Sprintf("%v", *p)
	_ = fmt.Sprint(&p)     // ok; prints address
	return fmt.Sprintln(p) // want `fmt.Sprintln arg p causes recursive call to \(\*a.recursivePtrError\).Error method`
}

type recursiveStringerAndError int

func (s recursiveStringerAndError) String() string {
	_ = fmt.Sprintf("%d", s)
	_ = fmt.Sprintf("%#v", s)
	_ = fmt.Sprintf("%v", s)   // want `fmt.Sprintf format %v with arg s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%v", &s)  // want `fmt.Sprintf format %v with arg &s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#x", s)  // want `fmt.Sprintf format %#x with arg s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#x", &s) // want `fmt.Sprintf format %#x with arg &s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#X", s)  // want `fmt.Sprintf format %#X with arg s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#X", &s) // want `fmt.Sprintf format %#X with arg &s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#q", s)  // want `fmt.Sprintf format %#q with arg s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%#q", &s) // want `fmt.Sprintf format %#q with arg &s causes recursive \(a.recursiveStringerAndError\).String method call`
	_ = fmt.Sprintf("%T", s)   // ok; does not recursively call String
	return fmt.Sprintln(s)     // want `fmt.Sprintln arg s causes recursive call to \(a.recursiveStringerAndError\).String method`
}

func (s recursiveStringerAndError) Error() string {
	_ = fmt.Sprintf("%d", s)
	_ = fmt.Sprintf("%#v", s)
	_ = fmt.Sprintf("%v", s)   // want `fmt.Sprintf format %v with arg s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%v", &s)  // want `fmt.Sprintf format %v with arg &s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#x", s)  // want `fmt.Sprintf format %#x with arg s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#x", &s) // want `fmt.Sprintf format %#x with arg &s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#X", s)  // want `fmt.Sprintf format %#X with arg s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#X", &s) // want `fmt.Sprintf format %#X with arg &s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#q", s)  // want `fmt.Sprintf format %#q with arg s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%#q", &s) // want `fmt.Sprintf format %#q with arg &s causes recursive \(a.recursiveStringerAndError\).Error method call`
	_ = fmt.Sprintf("%T", s)   // ok; does not recursively call Error
	return fmt.Sprintln(s)     // want `fmt.Sprintln arg s causes recursive call to \(a.recursiveStringerAndError\).Error method`
}

type recursivePtrStringerAndError int

func (p *recursivePtrStringerAndError) String() string {
	_ = fmt.Sprintf("%v", *p)
	_ = fmt.Sprint(&p)     // ok; prints address
	return fmt.Sprintln(p) // want `fmt.Sprintln arg p causes recursive call to \(\*a.recursivePtrStringerAndError\).String method`
}

func (p *recursivePtrStringerAndError) Error() string {
	_ = fmt.Sprintf("%v", *p)
	_ = fmt.Sprint(&p)     // ok; prints address
	return fmt.Sprintln(p) // want `fmt.Sprintln arg p causes recursive call to \(\*a.recursivePtrStringerAndError\).Error method`
}

// implements a String() method but with non-matching return types
type nonStringerWrongReturn int

func (s nonStringerWrongReturn) String() (string, error) {
	return "", fmt.Errorf("%v", s)
}

// implements a String() method but with non-matching arguments
type nonStringerWrongArgs int

func (s nonStringerWrongArgs) String(i int) string {
	return fmt.Sprintf("%d%v", i, s)
}

type cons struct {
	car int
	cdr *cons
}

func (cons *cons) String() string {
	if cons == nil {
		return "nil"
	}
	_ = fmt.Sprint(cons.cdr)                            // don't want "recursive call" diagnostic
	return fmt.Sprintf("(%d . %v)", cons.car, cons.cdr) // don't want "recursive call" diagnostic
}

type BoolFormatter bool

func (*BoolFormatter) Format(fmt.State, rune) {
}

// Formatter with value receiver
type FormatterVal bool

func (FormatterVal) Format(fmt.State, rune) {
}

type RecursiveSlice []RecursiveSlice

var recursiveSliceV = &RecursiveSlice{}

type RecursiveMap map[int]RecursiveMap

var recursiveMapV = make(RecursiveMap)

type RecursiveStruct struct {
	next *RecursiveStruct
}

var recursiveStructV = &RecursiveStruct{}

type RecursiveStruct1 struct {
	next *RecursiveStruct2
}

type RecursiveStruct2 struct {
	next *RecursiveStruct1
}

var recursiveStruct1V = &RecursiveStruct1{}

type unexportedInterface struct {
	f interface{}
}

// Issue 17798: unexported ptrStringer cannot be formatted.
type unexportedStringer struct {
	t ptrStringer
}

type unexportedStringerOtherFields struct {
	s string
	t ptrStringer
	S string
}

// Issue 17798: unexported error cannot be formatted.
type unexportedError struct {
	e error
}

type unexportedErrorOtherFields struct {
	s string
	e error
	S string
}

type errorer struct{}

func (e errorer) Error() string { return "errorer" }

type unexportedCustomError struct {
	e errorer
}

type errorInterface interface {
	error
	ExtraMethod()
}

type unexportedErrorInterface struct {
	e errorInterface
}

func UnexportedStringerOrError() {
	fmt.Printf("%s", unexportedInterface{"foo"}) // ok; prints {foo}
	fmt.Printf("%s", unexportedInterface{3})     // ok; we can't see the problem

	us := unexportedStringer{}
	fmt.Printf("%s", us)  // want "Printf format %s has arg us of wrong type a.unexportedStringer"
	fmt.Printf("%s", &us) // want "Printf format %s has arg &us of wrong type [*]a.unexportedStringer"

	usf := unexportedStringerOtherFields{
		s: "foo",
		S: "bar",
	}
	fmt.Printf("%s", usf)  // want "Printf format %s has arg usf of wrong type a.unexportedStringerOtherFields"
	fmt.Printf("%s", &usf) // want "Printf format %s has arg &usf of wrong type [*]a.unexportedStringerOtherFields"

	ue := unexportedError{
		e: &errorer{},
	}
	fmt.Printf("%s", ue)  // want "Printf format %s has arg ue of wrong type a.unexportedError"
	fmt.Printf("%s", &ue) // want "Printf format %s has arg &ue of wrong type [*]a.unexportedError"

	uef := unexportedErrorOtherFields{
		s: "foo",
		e: &errorer{},
		S: "bar",
	}
	fmt.Printf("%s", uef)  // want "Printf format %s has arg uef of wrong type a.unexportedErrorOtherFields"
	fmt.Printf("%s", &uef) // want "Printf format %s has arg &uef of wrong type [*]a.unexportedErrorOtherFields"

	uce := unexportedCustomError{
		e: errorer{},
	}
	fmt.Printf("%s", uce) // want "Printf format %s has arg uce of wrong type a.unexportedCustomError"

	uei := unexportedErrorInterface{}
	fmt.Printf("%s", uei)       // want "Printf format %s has arg uei of wrong type a.unexportedErrorInterface"
	fmt.Println("foo\n", "bar") // not an error

	fmt.Println("foo\n")      // want "Println arg list ends with redundant newline"
	fmt.Println("foo" + "\n") // want "Println arg list ends with redundant newline"
	fmt.Println("foo\\n")     // not an error
	fmt.Println(`foo\n`)      // not an error

	intSlice := []int{3, 4}
	fmt.Printf("%s", intSlice) // want `fmt.Printf format %s has arg intSlice of wrong type \[\]int`
	nonStringerArray := [1]unexportedStringer{{}}
	fmt.Printf("%s", nonStringerArray)  // want `fmt.Printf format %s has arg nonStringerArray of wrong type \[1\]a.unexportedStringer`
	fmt.Printf("%s", []stringer{3, 4})  // not an error
	fmt.Printf("%s", [2]stringer{3, 4}) // not an error
}

// TODO: Disable complaint about '0' for Go 1.10. To be fixed properly in 1.11.
// See issues 23598 and 23605.
func DisableErrorForFlag0() {
	fmt.Printf("%0t", true)
}

// Issue 26486.
func dbg(format string, args ...interface{}) {
	if format == "" {
		format = "%v"
	}
	fmt.Printf(format, args...)
}

func PointersToCompoundTypes() {
	stringSlice := []string{"a", "b"}
	fmt.Printf("%s", &stringSlice) // not an error

	intSlice := []int{3, 4}
	fmt.Printf("%s", &intSlice) // want `fmt.Printf format %s has arg &intSlice of wrong type \*\[\]int`

	stringArray := [2]string{"a", "b"}
	fmt.Printf("%s", &stringArray) // not an error

	intArray := [2]int{3, 4}
	fmt.Printf("%s", &intArray) // want `fmt.Printf format %s has arg &intArray of wrong type \*\[2\]int`

	stringStruct := struct{ F string }{"foo"}
	fmt.Printf("%s", &stringStruct) // not an error

	intStruct := struct{ F int }{3}
	fmt.Printf("%s", &intStruct) // want `fmt.Printf format %s has arg &intStruct of wrong type \*struct{F int}`

	stringMap := map[string]string{"foo": "bar"}
	fmt.Printf("%s", &stringMap) // not an error

	intMap := map[int]int{3: 4}
	fmt.Printf("%s", &intMap) // want `fmt.Printf format %s has arg &intMap of wrong type \*map\[int\]int`

	type T2 struct {
		X string
	}
	type T1 struct {
		X *T2
	}
	fmt.Printf("%s\n", T1{&T2{"x"}}) // want `fmt.Printf format %s has arg T1{&T2{.x.}} of wrong type a\.T1`
}

// Printf wrappers from external package
func externalPackage() {
	b.Wrapf("%s", 1) // want "Wrapf format %s has arg 1 of wrong type int"
	b.Wrap("%s", 1)  // want "Wrap call has possible Printf formatting directive %s"
	b.NoWrap("%s", 1)
	b.Wrapf2("%s", 1) // want "Wrapf2 format %s has arg 1 of wrong type int"
}

func PointerVerbs() {
	// Use booleans, so that we don't just format the elements like in
	// PointersToCompoundTypes. Bools can only be formatted with verbs like
	// %t and %v, and none of the ones below.
	ptr := new(bool)
	slice := []bool{}
	array := [3]bool{}
	map_ := map[bool]bool{}
	chan_ := make(chan bool)
	func_ := func(bool) {}

	// %p, %b, %d, %o, %O, %x, and %X all support pointers.
	fmt.Printf("%p", ptr)
	fmt.Printf("%b", ptr)
	fmt.Printf("%d", ptr)
	fmt.Printf("%o", ptr)
	fmt.Printf("%O", ptr)
	fmt.Printf("%x", ptr)
	fmt.Printf("%X", ptr)

	// %p, %b, %d, %o, %O, %x, and %X all support channels.
	fmt.Printf("%p", chan_)
	fmt.Printf("%b", chan_)
	fmt.Printf("%d", chan_)
	fmt.Printf("%o", chan_)
	fmt.Printf("%O", chan_)
	fmt.Printf("%x", chan_)
	fmt.Printf("%X", chan_)

	// %p is the only one that supports funcs.
	fmt.Printf("%p", func_)
	fmt.Printf("%b", func_) // want `fmt.Printf format %b arg func_ is a func value, not called`
	fmt.Printf("%d", func_) // want `fmt.Printf format %d arg func_ is a func value, not called`
	fmt.Printf("%o", func_) // want `fmt.Printf format %o arg func_ is a func value, not called`
	fmt.Printf("%O", func_) // want `fmt.Printf format %O arg func_ is a func value, not called`
	fmt.Printf("%x", func_) // want `fmt.Printf format %x arg func_ is a func value, not called`
	fmt.Printf("%X", func_) // want `fmt.Printf format %X arg func_ is a func value, not called`

	// %p is the only one that supports all slices, by printing the address
	// of the 0th element.
	fmt.Printf("%p", slice) // supported; address of 0th element
	fmt.Printf("%b", slice) // want `fmt.Printf format %b has arg slice of wrong type \[\]bool`

	fmt.Printf("%d", slice) // want `fmt.Printf format %d has arg slice of wrong type \[\]bool`

	fmt.Printf("%o", slice) // want `fmt.Printf format %o has arg slice of wrong type \[\]bool`
	fmt.Printf("%O", slice) // want `fmt.Printf format %O has arg slice of wrong type \[\]bool`

	fmt.Printf("%x", slice) // want `fmt.Printf format %x has arg slice of wrong type \[\]bool`
	fmt.Printf("%X", slice) // want `fmt.Printf format %X has arg slice of wrong type \[\]bool`

	// None support arrays.
	fmt.Printf("%p", array) // want `fmt.Printf format %p has arg array of wrong type \[3\]bool`
	fmt.Printf("%b", array) // want `fmt.Printf format %b has arg array of wrong type \[3\]bool`
	fmt.Printf("%d", array) // want `fmt.Printf format %d has arg array of wrong type \[3\]bool`
	fmt.Printf("%o", array) // want `fmt.Printf format %o has arg array of wrong type \[3\]bool`
	fmt.Printf("%O", array) // want `fmt.Printf format %O has arg array of wrong type \[3\]bool`
	fmt.Printf("%x", array) // want `fmt.Printf format %x has arg array of wrong type \[3\]bool`
	fmt.Printf("%X", array) // want `fmt.Printf format %X has arg array of wrong type \[3\]bool`

	// %p is the only one that supports all maps.
	fmt.Printf("%p", map_) // supported; address of 0th element
	fmt.Printf("%b", map_) // want `fmt.Printf format %b has arg map_ of wrong type map\[bool\]bool`

	fmt.Printf("%d", map_) // want `fmt.Printf format %d has arg map_ of wrong type map\[bool\]bool`

	fmt.Printf("%o", map_) // want `fmt.Printf format %o has arg map_ of wrong type map\[bool\]bool`
	fmt.Printf("%O", map_) // want `fmt.Printf format %O has arg map_ of wrong type map\[bool\]bool`

	fmt.Printf("%x", map_) // want `fmt.Printf format %x has arg map_ of wrong type map\[bool\]bool`
	fmt.Printf("%X", map_) // want `fmt.Printf format %X has arg map_ of wrong type map\[bool\]bool`
}

// Tests of calls to anonymous print{,f}-wrapper
// functions assigned to variables (local/package/field).

// Test a local assigned an anonymous function using :=.
func _() {
	printf := func(format string, args ...any) { // want printf:"printfWrapper"
		println(fmt.Sprintf(format, args...))
	}
	printf("%s", 123)                            // want `printf format %s has arg 123 of wrong type int`
	printf = nil                                 // this doesn't undo the variable's printf-wrapper status
	printf = func(format string, args ...any) {} // nor does this
	printf("%s", 123)                            // want `printf format %s has arg 123 of wrong type int`
}

// Test a global variable.
func _() {
	globalPrintf("%s", 123) // want `globalPrintf format %s has arg 123 of wrong type int`

	// This assignment causes calls to GlobalWrapf2 to
	// be checked as a wrapper in this package only.
	b.GlobalWrapf2 = func(format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	b.GlobalWrapf("%s", 123)    // want `GlobalWrapf format %s has arg 123 of wrong type int`
	b.GlobalWrapf2("%s", 123)   // want `GlobalWrapf2 format %s has arg 123 of wrong type int`
	b.GlobalNonWrapf("%s", 123) // nope
}

var globalPrintf = func(format string, args ...any) { // want globalPrintf:"printfWrapper"
	println(fmt.Sprintf(format, args...))
}

// Test a non-wrapper anonymous function with a plausible signature.
func _() {
	notprintf := func(format string, args ...any) {}
	notprintf("%s", 123)
}

// Test '=' assignment.
// Even calls through the var before it is
// assigned a printf-like value are checked.
func _() {
	var printf func(bogus int, format string, args ...any) // want printf:"printfWrapper"
	printf(0, "%s", 123)                                   // want `printf format %s has arg 123 of wrong type int`
	printf = func(bogus int, format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	printf(0, "%s", 123) // want `printf format %s has arg 123 of wrong type int`
}

// Test of literal wrapper function assigned to local variable.
func _() {
	var printf = func(format string, args ...any) { // want printf:"printfWrapper"
		println(fmt.Sprintf(format, args...))
	}
	printf("%s", 123) // want `printf format %s has arg 123 of wrong type int`
}

// Test of literal wrapper function assigned to struct field.
func _() {
	var local struct {
		printf func(format string, args ...any) // want printf:"printfWrapper"
	}
	local.printf = func(format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	local.printf("%s", 123) // want `printf format %s has arg 123 of wrong type int`

	// This assignment causes calls to Struct.Wrapf to
	// be checked as a wrapper in this package only.
	b.Struct.Wrapf2 = func(format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	b.Struct.Wrapf("%s", 123)    // want `Wrapf format %s has arg 123 of wrong type int`
	b.Struct.Wrapf2("%s", 123)   // want `Wrapf2 format %s has arg 123 of wrong type int`
	b.Struct.NonWrapf("%s", 123) // nope

	// variant using generic struct type.
	{
		type S[T any] struct {
			printf func(x T, format string, args ...any) // want printf:"printfWrapper"
		}
		new(S[bool]).printf = func(_ bool, format string, args ...any) {
			println(fmt.Sprintf(format, args...))
		}
		new(S[int]).printf(0, "%s", 123) // want `printf format %s has arg 123 of wrong type int`
	}
}


================================================
FILE: go/analysis/passes/printf/testdata/src/a/a2.go
================================================
//go:build go1.26

package a

// Test of induction through interface assignments. (Applies only to
// interface methods declared in files that use at least Go 1.26.)

import "fmt"

type myLogger int

func (myLogger) Logf(format string, args ...any) { // want Logf:"printfWrapper"
	print(fmt.Sprintf(format, args...))
}

// Logger is assigned from myLogger.

type Logger interface {
	Logf(format string, args ...any) // want Logf:"printfWrapper"
}

var _ Logger = myLogger(0) // establishes that Logger wraps myLogger

func _(log Logger) {
	log.Logf("%s", 123) // want `\(a.Logger\).Logf format %s has arg 123 of wrong type int`
}

// Logger2 is not assigned from myLogger.

type Logger2 interface {
	Logf(format string, args ...any)
}

func _(log Logger2) {
	log.Logf("%s", 123) // nope
}


================================================
FILE: go/analysis/passes/printf/testdata/src/b/b.go
================================================
package b

import "fmt"

// Wrapf is a printf wrapper.
func Wrapf(format string, args ...interface{}) { // want Wrapf:"printfWrapper"
	fmt.Sprintf(format, args...)
}

// Wrap is a print wrapper.
func Wrap(args ...interface{}) { // want Wrap:"printWrapper"
	fmt.Sprint(args...)
}

// NoWrap is not a wrapper.
func NoWrap(format string, args ...interface{}) {
}

// Wrapf2 is another printf wrapper.
func Wrapf2(format string, args ...interface{}) string { // want Wrapf2:"printfWrapper"

	// This statement serves as an assertion that this function is a
	// printf wrapper and that calls to it should be checked
	// accordingly, even though the delegation below is obscured by
	// the "("+format+")" operations.
	if false {
		fmt.Sprintf(format, args...)
	}

	// Effectively a printf delegation,
	// but the printf checker can't see it.
	return fmt.Sprintf("("+format+")", args...)
}

var (
	// GlobalWrapf is assigned a literal printf wrapper
	// in this package, and thus has a fact.
	GlobalWrapf func(format string, args ...interface{}) // want GlobalWrapf:"printfWrapper"

	// GlobalWrapf2 is also assigned, but in another package (a),
	// and thus has no fact. Nonetheless it is checked as a
	// wrapper in that package.
	GlobalWrapf2 func(format string, args ...interface{})

	// GlobalNonWrapf is never assigned a wrapper.
	GlobalNonWrapf func(format string, args ...interface{})
)

var Struct struct {
	// These fields follow the same pattern as the Global* vars.
	Wrapf    func(format string, args ...interface{}) // want Wrapf:"printfWrapper"
	Wrapf2   func(format string, args ...interface{})
	NonWrapf func(format string, args ...interface{})
}

func init() {
	GlobalWrapf = func(format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	GlobalWrapf("%s", 123)    // want "GlobalWrapf format %s has arg 123 of wrong type int"
	GlobalWrapf2("%s", 123)   // nope
	GlobalNonWrapf("%s", 123) // nope

	Struct.Wrapf = func(format string, args ...any) {
		println(fmt.Sprintf(format, args...))
	}
	Struct.Wrapf("%s", 123)    // want "Wrapf format %s has arg 123 of wrong type int"
	Struct.Wrapf2("%s", 123)   // nope
	Struct.NonWrapf("%s", 123) // nope
}


================================================
FILE: go/analysis/passes/printf/testdata/src/issue68744/issue68744.go
================================================
package issue68744

import "fmt"

// The use of "any" here is crucial to exercise the bug.
// (None of our earlier tests covered this vital detail!)
func wrapf(format string, args ...any) { // want wrapf:"printfWrapper"
	fmt.Printf(format, args...)
}

func _() {
	wrapf("%s", 123) // want `issue68744.wrapf format %s has arg 123 of wrong type int`
}


================================================
FILE: go/analysis/passes/printf/testdata/src/issue70572/issue70572.go
================================================
package issue70572

// Regression test for failure to detect that a call to B[bool].Printf
// was printf-like, because of a missing call to types.Func.Origin.

import "fmt"

type A struct{}

func (v A) Printf(format string, values ...any) { // want Printf:"printfWrapper"
	fmt.Printf(format, values...)
}

type B[T any] struct{}

func (v B[T]) Printf(format string, values ...any) { // want Printf:"printfWrapper"
	fmt.Printf(format, values...)
}

func main() {
	var a A
	var b B[bool]
	a.Printf("x", 1) // want "arguments but no formatting directives"
	b.Printf("x", 1) // want "arguments but no formatting directives"
}


================================================
FILE: go/analysis/passes/printf/testdata/src/issue72850/a_go125.go
================================================
//go:build !go1.26

package a

import "fmt"

var (
	_ = fmt.Sprintf("%q", byte(65)) // ok
	_ = fmt.Sprintf("%q", rune(65)) // ok
	_ = fmt.Sprintf("%q", 123)      // ok: pre-1.26 code allows %q on any integer
)


================================================
FILE: go/analysis/passes/printf/testdata/src/issue72850/a_go126.go
================================================
//go:build go1.26

package a

import "fmt"

var (
	_ = fmt.Sprintf("%q", byte(65)) // ok
	_ = fmt.Sprintf("%q", rune(65)) // ok
	_ = fmt.Sprintf("%q", 123)      // want `fmt.Sprintf format %q has arg 123 of wrong type int`
)


================================================
FILE: go/analysis/passes/printf/testdata/src/issue76616/issue76616.go
================================================
package issue76616

func _() {
	_ = func() {}
}


================================================
FILE: go/analysis/passes/printf/testdata/src/nofmt/nofmt.go
================================================
package b

import (
	"math/big"
	"testing"
)

func formatBigInt(t *testing.T) {
	t.Logf("%d\n", big.NewInt(4))
}


================================================
FILE: go/analysis/passes/printf/testdata/src/nonconst/nonconst.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests of the printf checker's handling of non-constant
// format strings (golang/go#60529).

package nonconst

import (
	"fmt"
	"log"
	"os"
)

// As the language version is empty here, and the new check is gated on go1.24,
// diagnostics are suppressed here.
func nonConstantFormat(s string) {
	fmt.Printf(s)
	fmt.Printf(s, "arg")
	fmt.Fprintf(os.Stderr, s)
	log.Printf(s)
}


================================================
FILE: go/analysis/passes/printf/testdata/src/typeparams/diagnostics.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "fmt"

func TestBasicTypeParams[T interface{ ~int }, E error, F fmt.Formatter, S fmt.Stringer, A any](t T, e E, f F, s S, a A) {
	fmt.Printf("%d", t)
	fmt.Printf("%s", t) // want "wrong type.*contains ~int"
	fmt.Printf("%v", t)
	fmt.Printf("%d", e) // want "wrong type"
	fmt.Printf("%s", e)
	fmt.Errorf("%w", e)
	fmt.Printf("%a", f)
	fmt.Printf("%d", f)
	fmt.Printf("%T", f.Format)
	fmt.Printf("%p", f.Format)
	fmt.Printf("%s", s)
	fmt.Errorf("%w", s) // want "wrong type"
	fmt.Printf("%d", a) // want "wrong type"
	fmt.Printf("%s", a) // want "wrong type"
	fmt.Printf("%v", a)
	fmt.Printf("%T", a)
}

type Constraint interface {
	~int
}

func TestNamedConstraints_Issue49597[T Constraint](t T) {
	fmt.Printf("%d", t)
	fmt.Printf("%s", t) // want "wrong type.*contains ~int"
}

func TestNestedTypeParams[T interface{ ~int }, S interface{ ~string }]() {
	var x struct {
		f int
		t T
	}
	fmt.Printf("%d", x)
	fmt.Printf("%s", x) // want "wrong type"
	var y struct {
		f string
		t S
	}
	fmt.Printf("%d", y) // want "wrong type"
	fmt.Printf("%s", y)
	var m1 map[T]T
	fmt.Printf("%d", m1)
	fmt.Printf("%s", m1) // want "wrong type"
	var m2 map[S]S
	fmt.Printf("%d", m2) // want "wrong type"
	fmt.Printf("%s", m2)
}

type R struct {
	F []R
}

func TestRecursiveTypeDefinition() {
	var r []R
	fmt.Printf("%d", r) // No error: avoids infinite recursion.
}

func TestRecursiveTypeParams[T1 ~[]T2, T2 ~[]T1 | string, T3 ~struct{ F T3 }](t1 T1, t2 T2, t3 T3) {
	// No error is reported on the following lines to avoid infinite recursion.
	fmt.Printf("%s", t1)
	fmt.Printf("%s", t2)
	fmt.Printf("%s", t3)
}

func TestRecusivePointers[T1 ~*T2, T2 ~*T1](t1 T1, t2 T2) {
	// No error: we can't determine if pointer rules apply.
	fmt.Printf("%s", t1)
	fmt.Printf("%s", t2)
}

func TestEmptyTypeSet[T interface {
	int | string
	float64
}](t T) {
	fmt.Printf("%s", t) // No error: empty type set.
}

func TestPointerRules[T ~*[]int | *[2]int](t T) {
	var slicePtr *[]int
	var arrayPtr *[2]int
	fmt.Printf("%d", slicePtr)
	fmt.Printf("%d", arrayPtr)
	fmt.Printf("%d", t)
}

func TestInterfacePromotion[E interface {
	~int
	Error() string
}, S interface {
	float64
	String() string
}](e E, s S) {
	fmt.Printf("%d", e)
	fmt.Printf("%s", e)
	fmt.Errorf("%w", e)
	fmt.Printf("%d", s) // want "wrong type.*contains float64"
	fmt.Printf("%s", s)
	fmt.Errorf("%w", s) // want "wrong type"
}

type myInt int

func TestTermReduction[T1 interface{ ~int | string }, T2 interface {
	~int | string
	myInt
}](t1 T1, t2 T2) {
	fmt.Printf("%d", t1) // want "wrong type.*contains string"
	fmt.Printf("%s", t1) // want "wrong type.*contains ~int"
	fmt.Printf("%d", t2)
	fmt.Printf("%s", t2) // want "wrong type.*contains typeparams.myInt"
}

type U[T any] struct{}

func (u U[T]) String() string {
	fmt.Println(u) // want `fmt.Println arg u causes recursive call to \(typeparams.U\[T\]\).String method`
	return ""
}

type S[T comparable] struct {
	t T
}

func (s S[T]) String() T {
	fmt.Println(s) // Not flagged. We currently do not consider String() T to implement fmt.Stringer (see #55928).
	return s.t
}

func TestInstanceStringer() {
	// Tests String method with nil Scope (#55350)
	fmt.Println(&S[string]{})
	fmt.Println(&U[string]{})
}


================================================
FILE: go/analysis/passes/printf/testdata/src/typeparams/wrappers.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "fmt"

type N[T any] int

func (N[P]) Wrapf(p P, format string, args ...interface{}) { // want Wrapf:"printfWrapper"
	fmt.Printf(format, args...)
}

func (*N[P]) PtrWrapf(p P, format string, args ...interface{}) { // want PtrWrapf:"printfWrapper"
	fmt.Printf(format, args...)
}

func Printf[P any](p P, format string, args ...interface{}) { // want Printf:"printfWrapper"
	fmt.Printf(format, args...)
}


================================================
FILE: go/analysis/passes/printf/types.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package printf

import (
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/typeparams"
)

var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

// matchArgType reports an error if printf verb t is not appropriate for
// operand arg.
//
// If arg is a type parameter, the verb t must be appropriate for every type in
// the type parameter type set.
func matchArgType(pass *analysis.Pass, t printfArgType, arg ast.Expr) (reason string, ok bool) {
	// %v, %T accept any argument type.
	if t == anyType {
		return "", true
	}

	typ := pass.TypesInfo.Types[arg].Type
	if typ == nil {
		return "", true // probably a type check problem
	}

	m := &argMatcher{t: t, seen: make(map[types.Type]bool)}
	ok = m.match(typ, true)
	return m.reason, ok
}

// argMatcher recursively matches types against the printfArgType t.
//
// To short-circuit recursion, it keeps track of types that have already been
// matched (or are in the process of being matched) via the seen map. Recursion
// arises from the compound types {map,chan,slice} which may be printed with %d
// etc. if that is appropriate for their element types, as well as from type
// parameters, which are expanded to the constituents of their type set.
//
// The reason field may be set to report the cause of the mismatch.
type argMatcher struct {
	t      printfArgType
	seen   map[types.Type]bool
	reason string
}

// match checks if typ matches m's printf arg type. If topLevel is true, typ is
// the actual type of the printf arg, for which special rules apply. As a
// special case, top level type parameters pass topLevel=true when checking for
// matches among the constituents of their type set, as type arguments will
// replace the type parameter at compile time.
func (m *argMatcher) match(typ types.Type, topLevel bool) bool {
	// %w accepts only errors.
	if m.t == argError {
		return types.ConvertibleTo(typ, errorType)
	}

	// If the type implements fmt.Formatter, we have nothing to check.
	if isFormatter(typ) {
		return true
	}

	// If we can use a string, might arg (dynamically) implement the Stringer or Error interface?
	if m.t&argString != 0 && isConvertibleToString(typ) {
		return true
	}

	if typ, _ := types.Unalias(typ).(*types.TypeParam); typ != nil {
		// Avoid infinite recursion through type parameters.
		if m.seen[typ] {
			return true
		}
		m.seen[typ] = true
		terms, err := typeparams.StructuralTerms(typ)
		if err != nil {
			return true // invalid type (possibly an empty type set)
		}

		if len(terms) == 0 {
			// No restrictions on the underlying of typ. Type parameters implementing
			// error, fmt.Formatter, or fmt.Stringer were handled above, and %v and
			// %T was handled in matchType. We're about to check restrictions the
			// underlying; if the underlying type is unrestricted there must be an
			// element of the type set that violates one of the arg type checks
			// below, so we can safely return false here.

			if m.t == anyType { // anyType must have already been handled.
				panic("unexpected printfArgType")
			}
			return false
		}

		// Only report a reason if typ is the argument type, otherwise it won't
		// make sense. Note that it is not sufficient to check if topLevel == here,
		// as type parameters can have a type set consisting of other type
		// parameters.
		reportReason := len(m.seen) == 1

		for _, term := range terms {
			if !m.match(term.Type(), topLevel) {
				if reportReason {
					if term.Tilde() {
						m.reason = fmt.Sprintf("contains ~%s", term.Type())
					} else {
						m.reason = fmt.Sprintf("contains %s", term.Type())
					}
				}
				return false
			}
		}
		return true
	}

	typ = typ.Underlying()
	if m.seen[typ] {
		// We've already considered typ, or are in the process of considering it.
		// In case we've already considered typ, it must have been valid (else we
		// would have stopped matching). In case we're in the process of
		// considering it, we must avoid infinite recursion.
		//
		// There are some pathological cases where returning true here is
		// incorrect, for example `type R struct { F []R }`, but these are
		// acceptable false negatives.
		return true
	}
	m.seen[typ] = true

	switch typ := typ.(type) {
	case *types.Signature:
		return m.t == argPointer

	case *types.Map:
		if m.t == argPointer {
			return true
		}
		// Recur: map[int]int matches %d.
		return m.match(typ.Key(), false) && m.match(typ.Elem(), false)

	case *types.Chan:
		return m.t&argPointer != 0

	case *types.Array:
		// Same as slice.
		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && m.t&argString != 0 {
			return true // %s matches []byte
		}
		// Recur: []int matches %d.
		return m.match(typ.Elem(), false)

	case *types.Slice:
		// Same as array.
		if types.Identical(typ.Elem().Underlying(), types.Typ[types.Byte]) && m.t&argString != 0 {
			return true // %s matches []byte
		}
		if m.t == argPointer {
			return true // %p prints a slice's 0th element
		}
		// Recur: []int matches %d. But watch out for
		//	type T []T
		// If the element is a pointer type (type T[]*T), it's handled fine by the Pointer case below.
		return m.match(typ.Elem(), false)

	case *types.Pointer:
		// Ugly, but dealing with an edge case: a known pointer to an invalid type,
		// probably something from a failed import.
		if typ.Elem() == types.Typ[types.Invalid] {
			return true // special case
		}
		// If it's actually a pointer with %p, it prints as one.
		if m.t == argPointer {
			return true
		}

		if typeparams.IsTypeParam(typ.Elem()) {
			return true // We don't know whether the logic below applies. Give up.
		}

		under := typ.Elem().Underlying()
		switch under.(type) {
		case *types.Struct: // see below
		case *types.Array: // see below
		case *types.Slice: // see below
		case *types.Map: // see below
		default:
			// Check whether the rest can print pointers.
			return m.t&argPointer != 0
		}
		// If it's a top-level pointer to a struct, array, slice, type param, or
		// map, that's equivalent in our analysis to whether we can
		// print the type being pointed to. Pointers in nested levels
		// are not supported to minimize fmt running into loops.
		if !topLevel {
			return false
		}
		return m.match(under, false)

	case *types.Struct:
		// report whether all the elements of the struct match the expected type. For
		// instance, with "%d" all the elements must be printable with the "%d" format.
		for typf := range typ.Fields() {
			if !m.match(typf.Type(), false) {
				return false
			}
			if m.t&argString != 0 && !typf.Exported() && isConvertibleToString(typf.Type()) {
				// Issue #17798: unexported Stringer or error cannot be properly formatted.
				return false
			}
		}
		return true

	case *types.Interface:
		// There's little we can do.
		// Whether any particular verb is valid depends on the argument.
		// The user may have reasonable prior knowledge of the contents of the interface.
		return true

	case *types.Basic:
		switch typ.Kind() {
		case types.UntypedBool,
			types.Bool:
			return m.t&argBool != 0

		case types.Byte:
			return m.t&(argInt|argByte) != 0

		case types.Rune, types.UntypedRune:
			return m.t&(argInt|argRune) != 0

		case types.UntypedInt,
			types.Int,
			types.Int8,
			types.Int16,
			// see case Rune for int32
			types.Int64,
			types.Uint,
			// see case Byte for uint8
			types.Uint16,
			types.Uint32,
			types.Uint64,
			types.Uintptr:
			return m.t&argInt != 0

		case types.UntypedFloat,
			types.Float32,
			types.Float64:
			return m.t&argFloat != 0

		case types.UntypedComplex,
			types.Complex64,
			types.Complex128:
			return m.t&argComplex != 0

		case types.UntypedString,
			types.String:
			return m.t&argString != 0

		case types.UnsafePointer:
			return m.t&(argPointer|argInt) != 0

		case types.UntypedNil:
			return false

		case types.Invalid:
			return true // Probably a type check problem.
		}
		panic("unreachable")
	}

	return false
}

func isConvertibleToString(typ types.Type) bool {
	if bt, ok := types.Unalias(typ).(*types.Basic); ok && bt.Kind() == types.UntypedNil {
		// We explicitly don't want untyped nil, which is
		// convertible to both of the interfaces below, as it
		// would just panic anyway.
		return false
	}
	if types.ConvertibleTo(typ, errorType) {
		return true // via .Error()
	}

	// Does it implement fmt.Stringer?
	if obj, _, _ := types.LookupFieldOrMethod(typ, false, nil, "String"); obj != nil {
		if fn, ok := obj.(*types.Func); ok {
			sig := fn.Type().(*types.Signature)
			if sig.Params().Len() == 0 &&
				sig.Results().Len() == 1 &&
				sig.Results().At(0).Type() == types.Typ[types.String] {
				return true
			}
		}
	}

	return false
}


================================================
FILE: go/analysis/passes/reflectvaluecompare/cmd/reflectvaluecompare/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The reflectvaluecompare command applies the reflectvaluecompare
// checker to the specified packages of Go source code.
//
// Run with:
//
//	$ go run ./go/analysis/passes/reflectvaluecompare/cmd/reflectvaluecompare -- packages...
package main

import (
	"golang.org/x/tools/go/analysis/passes/reflectvaluecompare"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(reflectvaluecompare.Analyzer) }


================================================
FILE: go/analysis/passes/reflectvaluecompare/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package reflectvaluecompare defines an Analyzer that checks for accidentally
// using == or reflect.DeepEqual to compare reflect.Value values.
// See issues 43993 and 18871.
//
// # Analyzer reflectvaluecompare
//
// reflectvaluecompare: check for comparing reflect.Value values with == or reflect.DeepEqual
//
// The reflectvaluecompare checker looks for expressions of the form:
//
//	v1 == v2
//	v1 != v2
//	reflect.DeepEqual(v1, v2)
//
// where v1 or v2 are reflect.Values. Comparing reflect.Values directly
// is almost certainly not correct, as it compares the reflect package's
// internal representation, not the underlying value.
// Likely what is intended is:
//
//	v1.Interface() == v2.Interface()
//	v1.Interface() != v2.Interface()
//	reflect.DeepEqual(v1.Interface(), v2.Interface())
package reflectvaluecompare


================================================
FILE: go/analysis/passes/reflectvaluecompare/reflectvaluecompare.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package reflectvaluecompare

import (
	_ "embed"
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "reflectvaluecompare",
	Doc:      analyzerutil.MustExtractDoc(doc, "reflectvaluecompare"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/reflectvaluecompare",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.BinaryExpr)(nil),
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.BinaryExpr:
			if n.Op != token.EQL && n.Op != token.NEQ {
				return
			}
			if isReflectValue(pass, n.X) || isReflectValue(pass, n.Y) {
				if n.Op == token.EQL {
					pass.ReportRangef(n, "avoid using == with reflect.Value")
				} else {
					pass.ReportRangef(n, "avoid using != with reflect.Value")
				}
			}
		case *ast.CallExpr:
			obj := typeutil.Callee(pass.TypesInfo, n)
			if typesinternal.IsFunctionNamed(obj, "reflect", "DeepEqual") && (isReflectValue(pass, n.Args[0]) || isReflectValue(pass, n.Args[1])) {
				pass.ReportRangef(n, "avoid using reflect.DeepEqual with reflect.Value")
			}
		}
	})
	return nil, nil
}

// isReflectValue reports whether the type of e is reflect.Value.
func isReflectValue(pass *analysis.Pass, e ast.Expr) bool {
	tv, ok := pass.TypesInfo.Types[e]
	if !ok { // no type info, something else is wrong
		return false
	}
	// See if the type is reflect.Value
	if !typesinternal.IsTypeNamed(tv.Type, "reflect", "Value") {
		return false
	}
	if _, ok := e.(*ast.CompositeLit); ok {
		// This is reflect.Value{}. Don't treat that as an error.
		// Users should probably use x.IsValid() rather than x == reflect.Value{}, but the latter isn't wrong.
		return false
	}
	return true
}


================================================
FILE: go/analysis/passes/reflectvaluecompare/reflectvaluecompare_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package reflectvaluecompare_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/reflectvaluecompare"
)

func TestReflectValueCompare(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, reflectvaluecompare.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/reflectvaluecompare/testdata/src/a/a.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the reflectvaluecompare checker.

package a

import (
	"reflect"
)

func f() {
	var x, y reflect.Value
	var a, b interface{}
	_ = x == y // want `avoid using == with reflect.Value`
	_ = x == a // want `avoid using == with reflect.Value`
	_ = a == x // want `avoid using == with reflect.Value`
	_ = a == b

	// Comparing to reflect.Value{} is ok.
	_ = a == reflect.Value{}
	_ = reflect.Value{} == a
	_ = reflect.Value{} == reflect.Value{}
}
func g() {
	var x, y reflect.Value
	var a, b interface{}
	_ = x != y // want `avoid using != with reflect.Value`
	_ = x != a // want `avoid using != with reflect.Value`
	_ = a != x // want `avoid using != with reflect.Value`
	_ = a != b

	// Comparing to reflect.Value{} is ok.
	_ = a != reflect.Value{}
	_ = reflect.Value{} != a
	_ = reflect.Value{} != reflect.Value{}
}
func h() {
	var x, y reflect.Value
	var a, b interface{}
	reflect.DeepEqual(x, y) // want `avoid using reflect.DeepEqual with reflect.Value`
	reflect.DeepEqual(x, a) // want `avoid using reflect.DeepEqual with reflect.Value`
	reflect.DeepEqual(a, x) // want `avoid using reflect.DeepEqual with reflect.Value`
	reflect.DeepEqual(a, b)

	// Comparing to reflect.Value{} is ok.
	reflect.DeepEqual(reflect.Value{}, a)
	reflect.DeepEqual(a, reflect.Value{})
	reflect.DeepEqual(reflect.Value{}, reflect.Value{})
}


================================================
FILE: go/analysis/passes/shadow/cmd/shadow/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The shadow command runs the shadow analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/shadow"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(shadow.Analyzer) }


================================================
FILE: go/analysis/passes/shadow/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package shadow defines an Analyzer that checks for shadowed variables.
//
// # Analyzer shadow
//
// shadow: check for possible unintended shadowing of variables
//
// This analyzer check for shadowed variables.
// A shadowed variable is a variable declared in an inner scope
// with the same name and type as a variable in an outer scope,
// and where the outer variable is mentioned after the inner one
// is declared.
//
// (This definition can be refined; the module generates too many
// false positives and is not yet enabled by default.)
//
// For example:
//
//	func BadRead(f *os.File, buf []byte) error {
//		var err error
//		for {
//			n, err := f.Read(buf) // shadows the function variable 'err'
//			if err != nil {
//				break // causes return of wrong value
//			}
//			foo(buf)
//		}
//		return err
//	}
package shadow


================================================
FILE: go/analysis/passes/shadow/shadow.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package shadow

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

// NOTE: Experimental. Not part of the vet suite.

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "shadow",
	Doc:      analyzerutil.MustExtractDoc(doc, "shadow"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shadow",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

// flags
var strict = false

func init() {
	Analyzer.Flags.BoolVar(&strict, "strict", strict, "whether to be strict about shadowing; can be noisy")
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	spans := make(map[types.Object]span)
	for id, obj := range pass.TypesInfo.Defs {
		// Ignore identifiers that don't denote objects
		// (package names, symbolic variables such as t
		// in t := x.(type) of type switch headers).
		if obj != nil {
			growSpan(spans, obj, id.Pos(), id.End())
		}
	}
	for id, obj := range pass.TypesInfo.Uses {
		growSpan(spans, obj, id.Pos(), id.End())
	}
	for node, obj := range pass.TypesInfo.Implicits {
		// A type switch with a short variable declaration
		// such as t := x.(type) doesn't declare the symbolic
		// variable (t in the example) at the switch header;
		// instead a new variable t (with specific type) is
		// declared implicitly for each case. Such variables
		// are found in the types.Info.Implicits (not Defs)
		// map. Add them here, assuming they are declared at
		// the type cases' colon ":".
		if cc, ok := node.(*ast.CaseClause); ok {
			growSpan(spans, obj, cc.Colon, cc.Colon)
		}
	}

	nodeFilter := []ast.Node{
		(*ast.AssignStmt)(nil),
		(*ast.GenDecl)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.AssignStmt:
			checkShadowAssignment(pass, spans, n)
		case *ast.GenDecl:
			checkShadowDecl(pass, spans, n)
		}
	})
	return nil, nil
}

// A span stores the minimum range of byte positions in the file in which a
// given variable (types.Object) is mentioned. It is lexically defined: it spans
// from the beginning of its first mention to the end of its last mention.
// A variable is considered shadowed (if strict is off) only if the
// shadowing variable is declared within the span of the shadowed variable.
// In other words, if a variable is shadowed but not used after the shadowed
// variable is declared, it is inconsequential and not worth complaining about.
// This simple check dramatically reduces the nuisance rate for the shadowing
// check, at least until something cleverer comes along.
//
// One wrinkle: A "naked return" is a silent use of a variable that the Span
// will not capture, but the compilers catch naked returns of shadowed
// variables so we don't need to.
//
// Cases this gets wrong (TODO):
// - If a for loop's continuation statement mentions a variable redeclared in
// the block, we should complain about it but don't.
// - A variable declared inside a function literal can falsely be identified
// as shadowing a variable in the outer function.
type span struct {
	min token.Pos
	max token.Pos
}

// contains reports whether the position is inside the span.
func (s span) contains(pos token.Pos) bool {
	return s.min <= pos && pos < s.max
}

// growSpan expands the span for the object to contain the source range [pos, end).
func growSpan(spans map[types.Object]span, obj types.Object, pos, end token.Pos) {
	if strict {
		return // No need
	}
	s, ok := spans[obj]
	if ok {
		if s.min > pos {
			s.min = pos
		}
		if s.max < end {
			s.max = end
		}
	} else {
		s = span{pos, end}
	}
	spans[obj] = s
}

// checkShadowAssignment checks for shadowing in a short variable declaration.
func checkShadowAssignment(pass *analysis.Pass, spans map[types.Object]span, a *ast.AssignStmt) {
	if a.Tok != token.DEFINE {
		return
	}
	if idiomaticShortRedecl(pass, a) {
		return
	}
	for _, expr := range a.Lhs {
		ident, ok := expr.(*ast.Ident)
		if !ok {
			pass.ReportRangef(expr, "invalid AST: short variable declaration of non-identifier")
			return
		}
		checkShadowing(pass, spans, ident)
	}
}

// idiomaticShortRedecl reports whether this short declaration can be ignored for
// the purposes of shadowing, that is, that any redeclarations it contains are deliberate.
func idiomaticShortRedecl(pass *analysis.Pass, a *ast.AssignStmt) bool {
	// Don't complain about deliberate redeclarations of the form
	//	i := i
	// Such constructs are idiomatic in range loops to create a new variable
	// for each iteration. Another example is
	//	switch n := n.(type)
	if len(a.Rhs) != len(a.Lhs) {
		return false
	}
	// We know it's an assignment, so the LHS must be all identifiers. (We check anyway.)
	for i, expr := range a.Lhs {
		lhs, ok := expr.(*ast.Ident)
		if !ok {
			pass.ReportRangef(expr, "invalid AST: short variable declaration of non-identifier")
			return true // Don't do any more processing.
		}
		switch rhs := a.Rhs[i].(type) {
		case *ast.Ident:
			if lhs.Name != rhs.Name {
				return false
			}
		case *ast.TypeAssertExpr:
			if id, ok := rhs.X.(*ast.Ident); ok {
				if lhs.Name != id.Name {
					return false
				}
			}
		default:
			return false
		}
	}
	return true
}

// idiomaticRedecl reports whether this declaration spec can be ignored for
// the purposes of shadowing, that is, that any redeclarations it contains are deliberate.
func idiomaticRedecl(d *ast.ValueSpec) bool {
	// Don't complain about deliberate redeclarations of the form
	//	var i, j = i, j
	// Don't ignore redeclarations of the form
	//	var i = 3
	if len(d.Names) != len(d.Values) {
		return false
	}
	for i, lhs := range d.Names {
		rhs, ok := d.Values[i].(*ast.Ident)
		if !ok || lhs.Name != rhs.Name {
			return false
		}
	}
	return true
}

// checkShadowDecl checks for shadowing in a general variable declaration.
func checkShadowDecl(pass *analysis.Pass, spans map[types.Object]span, d *ast.GenDecl) {
	if d.Tok != token.VAR {
		return
	}
	for _, spec := range d.Specs {
		valueSpec, ok := spec.(*ast.ValueSpec)
		if !ok {
			pass.ReportRangef(spec, "invalid AST: var GenDecl not ValueSpec")
			return
		}
		// Don't complain about deliberate redeclarations of the form
		//	var i = i
		if idiomaticRedecl(valueSpec) {
			return
		}
		for _, ident := range valueSpec.Names {
			checkShadowing(pass, spans, ident)
		}
	}
}

// checkShadowing checks whether the identifier shadows an identifier in an outer scope.
func checkShadowing(pass *analysis.Pass, spans map[types.Object]span, ident *ast.Ident) {
	if ident.Name == "_" {
		// Can't shadow the blank identifier.
		return
	}
	obj := pass.TypesInfo.Defs[ident]
	if obj == nil {
		return
	}
	// obj.Parent.Parent is the surrounding scope. If we can find another declaration
	// starting from there, we have a shadowed identifier.
	_, shadowed := obj.Parent().Parent().LookupParent(obj.Name(), obj.Pos())
	if shadowed == nil {
		return
	}
	// Don't complain if it's shadowing a universe-declared identifier; that's fine.
	if shadowed.Parent() == types.Universe {
		return
	}
	if strict {
		// The shadowed identifier must appear before this one to be an instance of shadowing.
		if shadowed.Pos() > ident.Pos() {
			return
		}
	} else {
		// Don't complain if the span of validity of the shadowed identifier doesn't include
		// the shadowing identifier.
		span, ok := spans[shadowed]
		if !ok {
			pass.ReportRangef(ident, "internal error: no range for %q", ident.Name)
			return
		}
		if !span.contains(ident.Pos()) {
			return
		}
	}
	// Don't complain if the types differ: that implies the programmer really wants two different things.
	if types.Identical(obj.Type(), shadowed.Type()) {
		line := pass.Fset.Position(shadowed.Pos()).Line
		pass.ReportRangef(ident, "declaration of %q shadows declaration at line %d", obj.Name(), line)
	}
}


================================================
FILE: go/analysis/passes/shadow/shadow_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package shadow_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/shadow"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, shadow.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/shadow/testdata/src/a/a.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the shadowed variable checker.
// Some of these errors are caught by the compiler (shadowed return parameters for example)
// but are nonetheless useful tests.

package a

import "os"

func ShadowRead(f *os.File, buf []byte) (err error) {
	var x int
	if f != nil {
		err := 3 // OK - different type.
		_ = err
	}
	if f != nil {
		_, err := f.Read(buf) // want "declaration of .err. shadows declaration at line 13"
		if err != nil {
			return err
		}
		i := 3 // OK
		_ = i
	}
	if f != nil {
		x := one()               // want "declaration of .x. shadows declaration at line 14"
		var _, err = f.Read(buf) // want "declaration of .err. shadows declaration at line 13"
		if x == 1 && err != nil {
			return err
		}
	}
	for i := 0; i < 10; i++ {
		i := i // OK: obviously intentional idiomatic redeclaration
		go func() {
			println(i)
		}()
	}
	var shadowTemp interface{}
	switch shadowTemp := shadowTemp.(type) { // OK: obviously intentional idiomatic redeclaration
	case int:
		println("OK")
		_ = shadowTemp
	}
	if shadowTemp := shadowTemp; true { // OK: obviously intentional idiomatic redeclaration
		var f *os.File // OK because f is not mentioned later in the function.
		// The declaration of x is a shadow because x is mentioned below.
		var x int // want "declaration of .x. shadows declaration at line 14"
		_, _, _ = x, f, shadowTemp
	}
	// Use a couple of variables to trigger shadowing errors.
	_, _ = err, x
	return
}

func one() int {
	return 1
}

// Must not complain with an internal error for the
// implicitly declared type switch variable v.
func issue26725(x interface{}) int {
	switch v := x.(type) {
	case int, int32:
		if v, ok := x.(int); ok {
			return v
		}
	case int64:
		return int(v)
	}
	return 0
}

// Verify that implicitly declared variables from
// type switches are considered in shadowing analysis.
func shadowTypeSwitch(a interface{}) {
	switch t := a.(type) {
	case int:
		{
			t := 0 // want "declaration of .t. shadows declaration at line 78"
			_ = t
		}
		_ = t
	case uint:
		{
			t := uint(0) // OK because t is not mentioned later in this function
			_ = t
		}
	}
}

func shadowBlock() {
	var a int
	{
		var a = 3 // want "declaration of .a. shadows declaration at line 94"
		_ = a
	}
	_ = a
}


================================================
FILE: go/analysis/passes/shift/dead.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package shift

// Simplified dead code detector.
// Used for skipping shift checks on unreachable arch-specific code.

import (
	"go/ast"
	"go/constant"
	"go/types"
)

// updateDead puts unreachable "if" and "case" nodes into dead.
func updateDead(info *types.Info, dead map[ast.Node]bool, node ast.Node) {
	if dead[node] {
		// The node is already marked as dead.
		return
	}

	// setDead marks the node and all the children as dead.
	setDead := func(n ast.Node) {
		ast.Inspect(n, func(node ast.Node) bool {
			if node != nil {
				dead[node] = true
			}
			return true
		})
	}

	switch stmt := node.(type) {
	case *ast.IfStmt:
		// "if" branch is dead if its condition evaluates
		// to constant false.
		v := info.Types[stmt.Cond].Value
		if v == nil {
			return
		}
		if !constant.BoolVal(v) {
			setDead(stmt.Body)
			return
		}
		if stmt.Else != nil {
			setDead(stmt.Else)
		}
	case *ast.SwitchStmt:
		// Case clause with empty switch tag is dead if it evaluates
		// to constant false.
		if stmt.Tag == nil {
		BodyLoopBool:
			for _, stmt := range stmt.Body.List {
				cc := stmt.(*ast.CaseClause)
				if cc.List == nil {
					// Skip default case.
					continue
				}
				for _, expr := range cc.List {
					v := info.Types[expr].Value
					if v == nil || v.Kind() != constant.Bool || constant.BoolVal(v) {
						continue BodyLoopBool
					}
				}
				setDead(cc)
			}
			return
		}

		// Case clause is dead if its constant value doesn't match
		// the constant value from the switch tag.
		// TODO: This handles integer comparisons only.
		v := info.Types[stmt.Tag].Value
		if v == nil || v.Kind() != constant.Int {
			return
		}
		tagN, ok := constant.Uint64Val(v)
		if !ok {
			return
		}
	BodyLoopInt:
		for _, x := range stmt.Body.List {
			cc := x.(*ast.CaseClause)
			if cc.List == nil {
				// Skip default case.
				continue
			}
			for _, expr := range cc.List {
				v := info.Types[expr].Value
				if v == nil {
					continue BodyLoopInt
				}
				n, ok := constant.Uint64Val(v)
				if !ok || tagN == n {
					continue BodyLoopInt
				}
			}
			setDead(cc)
		}
	}
}


================================================
FILE: go/analysis/passes/shift/shift.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package shift defines an Analyzer that checks for shifts that exceed
// the width of an integer.
package shift

// TODO(adonovan): integrate with ctrflow (CFG-based) dead code analysis. May
// have impedance mismatch due to its (non-)treatment of constant
// expressions (such as runtime.GOARCH=="386").

import (
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"math"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typeparams"
)

const Doc = "check for shifts that equal or exceed the width of the integer"

var Analyzer = &analysis.Analyzer{
	Name:     "shift",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shift",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// Do a complete pass to compute dead nodes.
	dead := make(map[ast.Node]bool)
	nodeFilter := []ast.Node{
		(*ast.IfStmt)(nil),
		(*ast.SwitchStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		// TODO(adonovan): move updateDead into this file.
		updateDead(pass.TypesInfo, dead, n)
	})

	nodeFilter = []ast.Node{
		(*ast.AssignStmt)(nil),
		(*ast.BinaryExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		if dead[node] {
			// Skip shift checks on unreachable nodes.
			return
		}

		switch node := node.(type) {
		case *ast.BinaryExpr:
			if node.Op == token.SHL || node.Op == token.SHR {
				checkLongShift(pass, node, node.X, node.Y)
			}
		case *ast.AssignStmt:
			if len(node.Lhs) != 1 || len(node.Rhs) != 1 {
				return
			}
			if node.Tok == token.SHL_ASSIGN || node.Tok == token.SHR_ASSIGN {
				checkLongShift(pass, node, node.Lhs[0], node.Rhs[0])
			}
		}
	})
	return nil, nil
}

// checkLongShift checks if shift or shift-assign operations shift by more than
// the length of the underlying variable.
func checkLongShift(pass *analysis.Pass, node ast.Node, x, y ast.Expr) {
	if pass.TypesInfo.Types[x].Value != nil {
		// Ignore shifts of constants.
		// These are frequently used for bit-twiddling tricks
		// like ^uint(0) >> 63 for 32/64 bit detection and compatibility.
		return
	}

	v := pass.TypesInfo.Types[y].Value
	if v == nil {
		return
	}
	u := constant.ToInt(v) // either an Int or Unknown
	amt, ok := constant.Int64Val(u)
	if !ok {
		return
	}
	t := pass.TypesInfo.Types[x].Type
	if t == nil {
		return
	}
	var structuralTypes []types.Type
	switch t := types.Unalias(t).(type) {
	case *types.TypeParam:
		terms, err := typeparams.StructuralTerms(t)
		if err != nil {
			return // invalid type
		}
		for _, term := range terms {
			structuralTypes = append(structuralTypes, term.Type())
		}
	default:
		structuralTypes = append(structuralTypes, t)
	}
	sizes := make(map[int64]struct{})
	for _, t := range structuralTypes {
		size := 8 * pass.TypesSizes.Sizeof(t)
		sizes[size] = struct{}{}
	}
	minSize := int64(math.MaxInt64)
	for size := range sizes {
		if size < minSize {
			minSize = size
		}
	}
	if amt >= minSize {
		ident := astutil.Format(pass.Fset, x)
		qualifier := ""
		if len(sizes) > 1 {
			qualifier = "may be "
		}
		pass.ReportRangef(node, "%s (%s%d bits) too small for shift of %d", ident, qualifier, minSize, amt)
	}
}


================================================
FILE: go/analysis/passes/shift/shift_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package shift_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/shift"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, shift.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/shift/testdata/src/a/a.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the suspicious shift checker.

package shift

import (
	"unsafe"
)

func ShiftTest() {
	var i8 int8
	_ = i8 << 7
	_ = (i8 + 1) << 8 // want ".i8 . 1. .8 bits. too small for shift of 8"
	_ = i8 << (7 + 1) // want "i8 .8 bits. too small for shift of 8"
	_ = i8 >> 8       // want "i8 .8 bits. too small for shift of 8"
	i8 <<= 8          // want "i8 .8 bits. too small for shift of 8"
	i8 >>= 8          // want "i8 .8 bits. too small for shift of 8"
	var i16 int16
	_ = i16 << 15
	_ = i16 << 16 // want "i16 .16 bits. too small for shift of 16"
	_ = i16 >> 16 // want "i16 .16 bits. too small for shift of 16"
	i16 <<= 16    // want "i16 .16 bits. too small for shift of 16"
	i16 >>= 16    // want "i16 .16 bits. too small for shift of 16"
	var i32 int32
	_ = i32 << 31
	_ = i32 << 32 // want "i32 .32 bits. too small for shift of 32"
	_ = i32 >> 32 // want "i32 .32 bits. too small for shift of 32"
	i32 <<= 32    // want "i32 .32 bits. too small for shift of 32"
	i32 >>= 32    // want "i32 .32 bits. too small for shift of 32"
	var i64 int64
	_ = i64 << 63
	_ = i64 << 64 // want "i64 .64 bits. too small for shift of 64"
	_ = i64 >> 64 // want "i64 .64 bits. too small for shift of 64"
	i64 <<= 64    // want "i64 .64 bits. too small for shift of 64"
	i64 >>= 64    // want "i64 .64 bits. too small for shift of 64"
	var u8 uint8
	_ = u8 << 7
	_ = u8 << 8 // want "u8 .8 bits. too small for shift of 8"
	_ = u8 >> 8 // want "u8 .8 bits. too small for shift of 8"
	u8 <<= 8    // want "u8 .8 bits. too small for shift of 8"
	u8 >>= 8    // want "u8 .8 bits. too small for shift of 8"
	var u16 uint16
	_ = u16 << 15
	_ = u16 << 16 // want "u16 .16 bits. too small for shift of 16"
	_ = u16 >> 16 // want "u16 .16 bits. too small for shift of 16"
	u16 <<= 16    // want "u16 .16 bits. too small for shift of 16"
	u16 >>= 16    // want "u16 .16 bits. too small for shift of 16"
	var u32 uint32
	_ = u32 << 31
	_ = u32 << 32 // want "u32 .32 bits. too small for shift of 32"
	_ = u32 >> 32 // want "u32 .32 bits. too small for shift of 32"
	u32 <<= 32    // want "u32 .32 bits. too small for shift of 32"
	u32 >>= 32    // want "u32 .32 bits. too small for shift of 32"
	var u64 uint64
	_ = u64 << 63
	_ = u64 << 64  // want "u64 .64 bits. too small for shift of 64"
	_ = u64 >> 64  // want "u64 .64 bits. too small for shift of 64"
	u64 <<= 64     // want "u64 .64 bits. too small for shift of 64"
	u64 >>= 64     // want "u64 .64 bits. too small for shift of 64"
	_ = u64 << u64 // Non-constant shifts should succeed.

	var i int
	_ = i << 31
	const in = 8 * unsafe.Sizeof(i)
	_ = i << in // want "too small for shift"
	_ = i >> in // want "too small for shift"
	i <<= in    // want "too small for shift"
	i >>= in    // want "too small for shift"
	const ix = 8*unsafe.Sizeof(i) - 1
	_ = i << ix
	_ = i >> ix
	i <<= ix
	i >>= ix

	var u uint
	_ = u << 31
	const un = 8 * unsafe.Sizeof(u)
	_ = u << un // want "too small for shift"
	_ = u >> un // want "too small for shift"
	u <<= un    // want "too small for shift"
	u >>= un    // want "too small for shift"
	const ux = 8*unsafe.Sizeof(u) - 1
	_ = u << ux
	_ = u >> ux
	u <<= ux
	u >>= ux

	var p uintptr
	_ = p << 31
	const pn = 8 * unsafe.Sizeof(p)
	_ = p << pn // want "too small for shift"
	_ = p >> pn // want "too small for shift"
	p <<= pn    // want "too small for shift"
	p >>= pn    // want "too small for shift"
	const px = 8*unsafe.Sizeof(p) - 1
	_ = p << px
	_ = p >> px
	p <<= px
	p >>= px

	const oneIf64Bit = ^uint(0) >> 63 // allow large shifts of constants; they are used for 32/64 bit compatibility tricks

	var h uintptr
	h = h<<8 | (h >> (8 * (unsafe.Sizeof(h) - 1)))
	h <<= 8 * unsafe.Sizeof(h) // want "too small for shift"
	h >>= 7 * unsafe.Alignof(h)
	h >>= 8 * unsafe.Alignof(h) // want "too small for shift"
}

func ShiftDeadCode() {
	var i int
	const iBits = 8 * unsafe.Sizeof(i)

	if iBits <= 32 {
		if iBits == 16 {
			_ = i >> 8
		} else {
			_ = i >> 16
		}
	} else {
		_ = i >> 32
	}

	if iBits >= 64 {
		_ = i << 32
		if iBits == 128 {
			_ = i << 64
		}
	} else {
		_ = i << 16
	}

	if iBits == 64 {
		_ = i << 32
	}

	switch iBits {
	case 128, 64:
		_ = i << 32
	default:
		_ = i << 16
	}

	switch {
	case iBits < 32:
		_ = i << 16
	case iBits > 64:
		_ = i << 64
	default:
		_ = i << 64 // want "too small for shift"
	}
}

func issue65939() {
	a := 1
	println(a << 2.0)
}


================================================
FILE: go/analysis/passes/shift/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "unsafe"

func GenericShiftTest[DifferentSize ~int8|int16|int64, SameSize int8|byte]() {
	var d DifferentSize
	_ = d << 7
	_ = d << 8        // want "d .may be 8 bits. too small for shift of 8"
	_ = d << 15       // want "d .may be 8 bits. too small for shift of 15"
	_ = (d + 1) << 8  // want ".d . 1. .may be 8 bits. too small for shift of 8"
	_ = (d + 1) << 16 // want ".d . 1. .may be 8 bits. too small for shift of 16"
	_ = d << (7 + 1)  // want "d .may be 8 bits. too small for shift of 8"
	_ = d >> 8        // want "d .may be 8 bits. too small for shift of 8"
	d <<= 8           // want "d .may be 8 bits. too small for shift of 8"
	d >>= 8           // want "d .may be 8 bits. too small for shift of 8"

	// go/types does not compute constant sizes for type parameters, so we do not
	// report a diagnostic here.
	_ = d << (8 * DifferentSize(unsafe.Sizeof(d)))

	var s SameSize
	_ = s << 7
	_ = s << 8        // want "s .8 bits. too small for shift of 8"
	_ = s << (7 + 1)  // want "s .8 bits. too small for shift of 8"
	_ = s >> 8        // want "s .8 bits. too small for shift of 8"
	s <<= 8           // want "s .8 bits. too small for shift of 8"
	s >>= 8           // want "s .8 bits. too small for shift of 8"
}


================================================
FILE: go/analysis/passes/sigchanyzer/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sigchanyzer defines an Analyzer that detects
// misuse of unbuffered signal as argument to signal.Notify.
//
// # Analyzer sigchanyzer
//
// sigchanyzer: check for unbuffered channel of os.Signal
//
// This checker reports call expression of the form
//
//	signal.Notify(c <-chan os.Signal, sig ...os.Signal),
//
// where c is an unbuffered channel, which can be at risk of missing the signal.
package sigchanyzer


================================================
FILE: go/analysis/passes/sigchanyzer/sigchanyzer.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sigchanyzer defines an Analyzer that detects
// misuse of unbuffered signal as argument to signal.Notify.
package sigchanyzer

import (
	"bytes"
	"slices"

	_ "embed"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

// Analyzer describes sigchanyzer analysis function detector.
var Analyzer = &analysis.Analyzer{
	Name:     "sigchanyzer",
	Doc:      analyzerutil.MustExtractDoc(doc, "sigchanyzer"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sigchanyzer",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "os/signal") {
		return nil, nil // doesn't directly import signal
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		if !isSignalNotify(pass.TypesInfo, call) {
			return
		}
		var chanDecl *ast.CallExpr
		switch arg := call.Args[0].(type) {
		case *ast.Ident:
			if decl, ok := findDecl(arg).(*ast.CallExpr); ok {
				chanDecl = decl
			}
		case *ast.CallExpr:
			// Only signal.Notify(make(chan os.Signal), os.Interrupt) is safe,
			// conservatively treat others as not safe, see golang/go#45043
			if isBuiltinMake(pass.TypesInfo, arg) {
				return
			}
			chanDecl = arg
		}
		if chanDecl == nil || len(chanDecl.Args) != 1 {
			return
		}

		// Make a copy of the channel's declaration to avoid
		// mutating the AST. See https://golang.org/issue/46129.
		chanDeclCopy := &ast.CallExpr{}
		*chanDeclCopy = *chanDecl
		chanDeclCopy.Args = slices.Clone(chanDecl.Args)
		chanDeclCopy.Args = append(chanDeclCopy.Args, &ast.BasicLit{
			Kind:  token.INT,
			Value: "1",
		})

		var buf bytes.Buffer
		if err := format.Node(&buf, token.NewFileSet(), chanDeclCopy); err != nil {
			return
		}
		pass.Report(analysis.Diagnostic{
			Pos:     call.Pos(),
			End:     call.End(),
			Message: "misuse of unbuffered os.Signal channel as argument to signal.Notify",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Change to buffer channel",
				TextEdits: []analysis.TextEdit{{
					Pos:     chanDecl.Pos(),
					End:     chanDecl.End(),
					NewText: buf.Bytes(),
				}},
			}},
		})
	})
	return nil, nil
}

func isSignalNotify(info *types.Info, call *ast.CallExpr) bool {
	check := func(id *ast.Ident) bool {
		obj := info.ObjectOf(id)
		return obj.Name() == "Notify" && obj.Pkg().Path() == "os/signal"
	}
	switch fun := call.Fun.(type) {
	case *ast.SelectorExpr:
		return check(fun.Sel)
	case *ast.Ident:
		if fun, ok := findDecl(fun).(*ast.SelectorExpr); ok {
			return check(fun.Sel)
		}
		return false
	default:
		return false
	}
}

func findDecl(arg *ast.Ident) ast.Node {
	if arg.Obj == nil {
		return nil
	}
	switch as := arg.Obj.Decl.(type) {
	case *ast.AssignStmt:
		if len(as.Lhs) != len(as.Rhs) {
			return nil
		}
		for i, lhs := range as.Lhs {
			lid, ok := lhs.(*ast.Ident)
			if !ok {
				continue
			}
			if lid.Obj == arg.Obj {
				return as.Rhs[i]
			}
		}
	case *ast.ValueSpec:
		if len(as.Names) != len(as.Values) {
			return nil
		}
		for i, name := range as.Names {
			if name.Obj == arg.Obj {
				return as.Values[i]
			}
		}
	}
	return nil
}

func isBuiltinMake(info *types.Info, call *ast.CallExpr) bool {
	typVal := info.Types[call.Fun]
	if !typVal.IsBuiltin() {
		return false
	}
	switch fun := call.Fun.(type) {
	case *ast.Ident:
		return info.ObjectOf(fun).Name() == "make"
	default:
		return false
	}
}


================================================
FILE: go/analysis/passes/sigchanyzer/sigchanyzer_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sigchanyzer_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/sigchanyzer"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, sigchanyzer.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/sigchanyzer/testdata/src/a/a.go
================================================
package p

import (
	"os"
	ao "os"
	"os/signal"
)

var c = make(chan os.Signal)
var d = make(chan os.Signal)

func f() {
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt) // ok
	_ = <-c
}

func g() {
	c := make(chan os.Signal)
	signal.Notify(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
	_ = <-c
}

func h() {
	c := make(chan ao.Signal)
	signal.Notify(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
	_ = <-c
}

func i() {
	signal.Notify(d, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
}

func j() {
	c := make(chan os.Signal)
	f := signal.Notify
	f(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
}

func k() {
	signal.Notify(make(chan os.Signal), os.Interrupt) // ok
}

func l() {
	signal.Notify(make(chan os.Signal, 1), os.Interrupt) // ok
}

func m() {
	signal.Notify(make(chan ao.Signal, 1), os.Interrupt) // ok
}

func n() {
	signal.Notify(make(chan ao.Signal), os.Interrupt) // ok
}


================================================
FILE: go/analysis/passes/sigchanyzer/testdata/src/a/a.go.golden
================================================
package p

import (
	"os"
	ao "os"
	"os/signal"
)

var c = make(chan os.Signal)
var d = make(chan os.Signal, 1)

func f() {
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt) // ok
	_ = <-c
}

func g() {
	c := make(chan os.Signal, 1)
	signal.Notify(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
	_ = <-c
}

func h() {
	c := make(chan ao.Signal, 1)
	signal.Notify(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
	_ = <-c
}

func i() {
	signal.Notify(d, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
}

func j() {
	c := make(chan os.Signal, 1)
	f := signal.Notify
	f(c, os.Interrupt) // want "misuse of unbuffered os.Signal channel as argument to signal.Notify"
}

func k() {
	signal.Notify(make(chan os.Signal), os.Interrupt) // ok
}

func l() {
	signal.Notify(make(chan os.Signal, 1), os.Interrupt) // ok
}

func m() {
	signal.Notify(make(chan ao.Signal, 1), os.Interrupt) // ok
}

func n() {
	signal.Notify(make(chan ao.Signal), os.Interrupt) // ok
}


================================================
FILE: go/analysis/passes/slog/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package slog defines an Analyzer that checks for
// mismatched key-value pairs in log/slog calls.
//
// # Analyzer slog
//
// slog: check for invalid structured logging calls
//
// The slog checker looks for calls to functions from the log/slog
// package that take alternating key-value pairs. It reports calls
// where an argument in a key position is neither a string nor a
// slog.Attr, and where a final key is missing its value.
// For example,it would report
//
//	slog.Warn("message", 11, "k") // slog.Warn arg "11" should be a string or a slog.Attr
//
// and
//
//	slog.Info("message", "k1", v1, "k2") // call to slog.Info missing a final value
package slog


================================================
FILE: go/analysis/passes/slog/slog.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// TODO(jba) deduce which functions wrap the log/slog functions, and use the
// fact mechanism to propagate this information, so we can provide diagnostics
// for user-supplied wrappers.

package slog

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "slog",
	Doc:      analyzerutil.MustExtractDoc(doc, "slog"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/slog",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

var stringType = types.Universe.Lookup("string").Type()

// A position describes what is expected to appear in an argument position.
type position int

const (
	// key is an argument position that should hold a string key or an Attr.
	key position = iota
	// value is an argument position that should hold a value.
	value
	// unknown represents that we do not know if position should hold a key or a value.
	unknown
)

func run(pass *analysis.Pass) (any, error) {
	var attrType types.Type // The type of slog.Attr
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		call := node.(*ast.CallExpr)
		fn := typeutil.StaticCallee(pass.TypesInfo, call)
		if fn == nil {
			return // not a static call
		}
		if call.Ellipsis != token.NoPos {
			return // skip calls with "..." args
		}
		skipArgs, ok := kvFuncSkipArgs(fn)
		if !ok {
			// Not a slog function that takes key-value pairs.
			return
		}
		// Here we know that fn.Pkg() is "log/slog".
		if attrType == nil {
			attrType = fn.Pkg().Scope().Lookup("Attr").Type()
		}

		if isMethodExpr(pass.TypesInfo, call) {
			// Call is to a method value. Skip the first argument.
			skipArgs++
		}
		if len(call.Args) <= skipArgs {
			// Too few args; perhaps there are no k-v pairs.
			return
		}

		// Check this call.
		// The first position should hold a key or Attr.
		pos := key
		var unknownArg ast.Expr // nil or the last unknown argument
		for _, arg := range call.Args[skipArgs:] {
			t := pass.TypesInfo.Types[arg].Type
			switch pos {
			case key:
				// Expect a string or Attr.
				switch {
				case t == stringType:
					pos = value
				case isAttr(t):
					pos = key
				case types.IsInterface(t):
					// As we do not do dataflow, we do not know what the dynamic type is.
					// But we might be able to learn enough to make a decision.
					if types.AssignableTo(stringType, t) {
						// t must be an empty interface. So it can also be an Attr.
						// We don't know enough to make an assumption.
						pos = unknown
						continue
					} else if attrType != nil && types.AssignableTo(attrType, t) {
						// Assume it is an Attr.
						pos = key
						continue
					}
					// Can't be either a string or Attr. Definitely an error.
					fallthrough
				default:
					if unknownArg == nil {
						pass.ReportRangef(arg, "%s arg %q should be a string or a slog.Attr (possible missing key or value)",
							shortName(fn), astutil.Format(pass.Fset, arg))
					} else {
						pass.ReportRangef(arg, "%s arg %q should probably be a string or a slog.Attr (previous arg %q cannot be a key)",
							shortName(fn), astutil.Format(pass.Fset, arg), astutil.Format(pass.Fset, unknownArg))
					}
					// Stop here so we report at most one missing key per call.
					return
				}

			case value:
				// Anything can appear in this position.
				// The next position should be a key.
				pos = key

			case unknown:
				// Once we encounter an unknown position, we can never be
				// sure if a problem later or at the end of the call is due to a
				// missing final value, or a non-key in key position.
				// In both cases, unknownArg != nil.
				unknownArg = arg

				// We don't know what is expected about this position, but all hope is not lost.
				if t != stringType && !isAttr(t) && !types.IsInterface(t) {
					// This argument is definitely not a key.
					//
					// unknownArg cannot have been a key, in which case this is the
					// corresponding value, and the next position should hold another key.
					pos = key
				}
			}
		}
		if pos == value {
			if unknownArg == nil {
				pass.ReportRangef(call, "call to %s missing a final value", shortName(fn))
			} else {
				pass.ReportRangef(call, "call to %s has a missing or misplaced value", shortName(fn))
			}
		}
	})
	return nil, nil
}

func isAttr(t types.Type) bool {
	return typesinternal.IsTypeNamed(t, "log/slog", "Attr")
}

// shortName returns a name for the function that is shorter than FullName.
// Examples:
//
//	"slog.Info" (instead of "log/slog.Info")
//	"slog.Logger.With" (instead of "(*log/slog.Logger).With")
func shortName(fn *types.Func) string {
	var r string
	if recv := fn.Signature().Recv(); recv != nil {
		if _, named := typesinternal.ReceiverNamed(recv); named != nil {
			r = named.Obj().Name()
		} else {
			r = recv.Type().String() // anon struct/interface
		}
		r += "."
	}
	return fmt.Sprintf("%s.%s%s", fn.Pkg().Name(), r, fn.Name())
}

// If fn is a slog function that has a ...any parameter for key-value pairs,
// kvFuncSkipArgs returns the number of arguments to skip over to reach the
// corresponding arguments, and true.
// Otherwise it returns (0, false).
func kvFuncSkipArgs(fn *types.Func) (int, bool) {
	if pkg := fn.Pkg(); pkg == nil || pkg.Path() != "log/slog" {
		return 0, false
	}
	var recvName string // by default a slog package function
	if recv := fn.Signature().Recv(); recv != nil {
		_, named := typesinternal.ReceiverNamed(recv)
		if named == nil {
			return 0, false // anon struct/interface
		}
		recvName = named.Obj().Name()
	}
	skip, ok := kvFuncs[recvName][fn.Name()]
	return skip, ok
}

// The names of functions and methods in log/slog that take
// ...any for key-value pairs, mapped to the number of initial args to skip in
// order to get to the ones that match the ...any parameter.
// The first key is the dereferenced receiver type name, or "" for a function.
var kvFuncs = map[string]map[string]int{
	"": {
		"Debug":        1,
		"Info":         1,
		"Warn":         1,
		"Error":        1,
		"DebugContext": 2,
		"InfoContext":  2,
		"WarnContext":  2,
		"ErrorContext": 2,
		"Log":          3,
		"Group":        1,
	},
	"Logger": {
		"Debug":        1,
		"Info":         1,
		"Warn":         1,
		"Error":        1,
		"DebugContext": 2,
		"InfoContext":  2,
		"WarnContext":  2,
		"ErrorContext": 2,
		"Log":          3,
		"With":         0,
	},
	"Record": {
		"Add": 0,
	},
}

// isMethodExpr reports whether a call is to a MethodExpr.
func isMethodExpr(info *types.Info, c *ast.CallExpr) bool {
	s, ok := c.Fun.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	sel := info.Selections[s]
	return sel != nil && sel.Kind() == types.MethodExpr
}


================================================
FILE: go/analysis/passes/slog/slog_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package slog

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, Analyzer, "a", "b")
}


================================================
FILE: go/analysis/passes/slog/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the slog checker.

//go:build go1.21

package a

import (
	"context"
	"errors"
	"fmt"
	"log/slog"
)

func F() {
	var (
		l *slog.Logger
		r slog.Record
	)

	// Unrelated call.
	fmt.Println("ok")

	// Valid calls.
	slog.Info("msg")
	slog.Info("msg", "a", 1)
	slog.Info("", "a", 1, "b", "two")
	l.Debug("msg", "a", 1)
	l.With("a", 1)
	slog.Warn("msg", slog.Int("a", 1))
	slog.Warn("msg", slog.Int("a", 1), "k", 2)
	l.WarnContext(nil, "msg", "a", 1, slog.Int("b", 2), slog.Int("c", 3), "d", 4)
	l.DebugContext(nil, "msg", "a", 1, slog.Int("b", 2), slog.Int("c", 3), "d", 4, slog.Int("e", 5))
	r.Add("a", 1, "b", 2)
	(*slog.Logger).Debug(l, "msg", "a", 1, "b", 2)

	var key string
	r.Add(key, 1)

	// bad
	slog.Info("msg", 1)                        // want `slog.Info arg "1" should be a string or a slog.Attr`
	l.Info("msg", 2)                           // want `slog.Logger.Info arg "2" should be a string or a slog.Attr`
	slog.Debug("msg", "a")                     // want `call to slog.Debug missing a final value`
	slog.Warn("msg", slog.Int("a", 1), "k")    // want `call to slog.Warn missing a final value`
	slog.ErrorContext(nil, "msg", "a", 1, "b") // want `call to slog.ErrorContext missing a final value`
	r.Add("K", "v", "k")                       // want `call to slog.Record.Add missing a final value`
	l.With("a", "b", 2)                        // want `slog.Logger.With arg "2" should be a string or a slog.Attr`

	// Report the first problem if there are multiple bad keys.
	slog.Debug("msg", "a", 1, 2, 3, 4) // want `slog.Debug arg "2" should be a string or a slog.Attr`
	slog.Debug("msg", "a", 1, 2, 3, 4) // want `slog.Debug arg "2" should be a string or a slog.Attr`

	slog.Log(nil, slog.LevelWarn, "msg", "a", "b", 2) // want `slog.Log arg "2" should be a string or a slog.Attr`

	// Test method expression call.
	(*slog.Logger).Debug(l, "msg", "a", 1, 2, 3) // want `slog.Logger.Debug arg "2" should be a string or a slog.Attr`

	// Skip calls with spread args.
	var args []any
	slog.Info("msg", args...)

	// Report keys that are statically not exactly "string".
	type MyString string
	myKey := MyString("a")  // any(x) looks like <MyString, "a">.
	slog.Info("", myKey, 1) // want `slog.Info arg "myKey" should be a string or a slog.Attr`

	// The variadic part of all the calls below begins with an argument of
	// static type any, followed by an integer.
	// Even though the we don't know the dynamic type of the first arg, and thus
	// whether it is a key, an Attr, or something else, the fact that the
	// following integer arg cannot be a key allows us to assume that we should
	// expect a key to follow.
	var a any = "key"

	// This is a valid call for which  we correctly produce no diagnostic.
	slog.Info("msg", a, 7, "key2", 5)

	// This is an invalid call because the final value is missing, but we can't
	// be sure that's the reason.
	slog.Info("msg", a, 7, "key2") // want `call to slog.Info has a missing or misplaced value`

	// Here our guess about the unknown arg (a) is wrong: we assume it's a string, but it's an Attr.
	// Therefore the second argument should be a key, but it is a number.
	// Ideally our diagnostic would pinpoint the problem, but we don't have enough information.
	a = slog.Int("a", 1)
	slog.Info("msg", a, 7, "key2") // want `call to slog.Info has a missing or misplaced value`

	// This call is invalid for the same reason as the one above, but we can't
	// detect that.
	slog.Info("msg", a, 7, "key2", 5)

	// Another invalid call we can't detect. Here the first argument is wrong.
	a = 1
	slog.Info("msg", a, 7, "b", 5)

	// We can detect the first case as the type of key is UntypedNil,
	// e.g. not yet assigned to any and not yet an interface.
	// We cannot detect the second.
	slog.Debug("msg", nil, 2) // want `slog.Debug arg "nil" should be a string or a slog.Attr`
	slog.Debug("msg", any(nil), 2)

	// Recovery from unknown value.
	slog.Debug("msg", any(nil), "a")
	slog.Debug("msg", any(nil), "a", 2)
	slog.Debug("msg", any(nil), "a", 2, "b") // want `call to slog.Debug has a missing or misplaced value`
	slog.Debug("msg", any(nil), 2, 3, 4)     // want "slog.Debug arg \\\"3\\\" should probably be a string or a slog.Attr \\(previous arg \\\"2\\\" cannot be a key\\)"

	// In these cases, an argument in key position is an interface, but we can glean useful information about it.

	// An error interface in key position is definitely invalid: it can't be a string
	// or slog.Attr.
	var err error
	slog.Error("msg", err) // want `slog.Error arg "err" should be a string or a slog.Attr`

	// slog.Attr implements fmt.Stringer, but string does not, so assume the arg is an Attr.
	var stringer fmt.Stringer
	slog.Info("msg", stringer, "a", 1)
	slog.Info("msg", stringer, 1) // want `slog.Info arg "1" should be a string or a slog.Attr`
}

func All() {
	// Test all functions and methods at least once.
	var (
		l   *slog.Logger
		r   slog.Record
		ctx context.Context
	)
	slog.Debug("msg", 1, 2) // want `slog.Debug arg "1" should be a string or a slog.Attr`
	slog.Error("msg", 1, 2) // want `slog.Error arg "1" should be a string or a slog.Attr`
	slog.Info("msg", 1, 2)  // want `slog.Info arg "1" should be a string or a slog.Attr`
	slog.Warn("msg", 1, 2)  // want `slog.Warn arg "1" should be a string or a slog.Attr`

	slog.DebugContext(ctx, "msg", 1, 2) // want `slog.DebugContext arg "1" should be a string or a slog.Attr`
	slog.ErrorContext(ctx, "msg", 1, 2) // want `slog.ErrorContext arg "1" should be a string or a slog.Attr`
	slog.InfoContext(ctx, "msg", 1, 2)  // want `slog.InfoContext arg "1" should be a string or a slog.Attr`
	slog.WarnContext(ctx, "msg", 1, 2)  // want `slog.WarnContext arg "1" should be a string or a slog.Attr`

	slog.Log(ctx, slog.LevelDebug, "msg", 1, 2) // want `slog.Log arg "1" should be a string or a slog.Attr`

	l.Debug("msg", 1, 2) // want `slog.Logger.Debug arg "1" should be a string or a slog.Attr`
	l.Error("msg", 1, 2) // want `slog.Logger.Error arg "1" should be a string or a slog.Attr`
	l.Info("msg", 1, 2)  // want `slog.Logger.Info arg "1" should be a string or a slog.Attr`
	l.Warn("msg", 1, 2)  // want `slog.Logger.Warn arg "1" should be a string or a slog.Attr`

	l.DebugContext(ctx, "msg", 1, 2) // want `slog.Logger.DebugContext arg "1" should be a string or a slog.Attr`
	l.ErrorContext(ctx, "msg", 1, 2) // want `slog.Logger.ErrorContext arg "1" should be a string or a slog.Attr`
	l.InfoContext(ctx, "msg", 1, 2)  // want `slog.Logger.InfoContext arg "1" should be a string or a slog.Attr`
	l.WarnContext(ctx, "msg", 1, 2)  // want `slog.Logger.WarnContext arg "1" should be a string or a slog.Attr`

	l.Log(ctx, slog.LevelDebug, "msg", 1, 2) // want `slog.Logger.Log arg "1" should be a string or a slog.Attr`

	_ = l.With(1, 2) // want `slog.Logger.With arg "1" should be a string or a slog.Attr`

	r.Add(1, 2) // want `slog.Record.Add arg "1" should be a string or a slog.Attr`

	_ = slog.Group("key", "a", 1, "b", 2)
	_ = slog.Group("key", "a", 1, 2, 3) // want `slog.Group arg "2" should be a string or a slog.Attr`

	slog.Error("foo", "err", errors.New("oops")) // regression test for #61228.
}

// Used in tests by package b.
var MyLogger = slog.Default()


================================================
FILE: go/analysis/passes/slog/testdata/src/b/b.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the slog checker.

//go:build go1.21

package b

import "a"

func Imported() {
	_ = a.MyLogger.With("a", 1, 2, 3) // want `slog.Logger.With arg "2" should be a string or a slog.Attr`
}


================================================
FILE: go/analysis/passes/sortslice/analyzer.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sortslice defines an Analyzer that checks for calls
// to sort.Slice that do not use a slice type as first argument.
package sortslice

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

const Doc = `check the argument type of sort.Slice

sort.Slice requires an argument of a slice type. Check that
the interface{} value passed to sort.Slice is actually a slice.`

var Analyzer = &analysis.Analyzer{
	Name:     "sortslice",
	Doc:      Doc,
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sortslice",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "sort") {
		return nil, nil // doesn't directly import sort
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}

	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		obj := typeutil.Callee(pass.TypesInfo, call)
		if !typesinternal.IsFunctionNamed(obj, "sort", "Slice", "SliceStable", "SliceIsSorted") {
			return
		}
		callee := obj.(*types.Func)

		arg := call.Args[0]
		typ := pass.TypesInfo.Types[arg].Type

		if tuple, ok := typ.(*types.Tuple); ok {
			typ = tuple.At(0).Type() // special case for Slice(f(...))
		}

		switch typ.Underlying().(type) {
		case *types.Slice, *types.Interface:
			return
		}

		// Restore typ to the original type, we may unwrap the tuple above,
		// typ might not be the type of arg.
		typ = pass.TypesInfo.Types[arg].Type

		var fixes []analysis.SuggestedFix
		switch v := typ.Underlying().(type) {
		case *types.Array:
			var buf bytes.Buffer
			format.Node(&buf, pass.Fset, &ast.SliceExpr{
				X:      arg,
				Slice3: false,
				Lbrack: arg.End() + 1,
				Rbrack: arg.End() + 3,
			})
			fixes = append(fixes, analysis.SuggestedFix{
				Message: "Get a slice of the full array",
				TextEdits: []analysis.TextEdit{{
					Pos:     arg.Pos(),
					End:     arg.End(),
					NewText: buf.Bytes(),
				}},
			})
		case *types.Pointer:
			_, ok := v.Elem().Underlying().(*types.Slice)
			if !ok {
				break
			}
			var buf bytes.Buffer
			format.Node(&buf, pass.Fset, &ast.StarExpr{
				X: arg,
			})
			fixes = append(fixes, analysis.SuggestedFix{
				Message: "Dereference the pointer to the slice",
				TextEdits: []analysis.TextEdit{{
					Pos:     arg.Pos(),
					End:     arg.End(),
					NewText: buf.Bytes(),
				}},
			})
		case *types.Signature:
			if v.Params().Len() != 0 || v.Results().Len() != 1 {
				break
			}
			if _, ok := v.Results().At(0).Type().Underlying().(*types.Slice); !ok {
				break
			}
			var buf bytes.Buffer
			format.Node(&buf, pass.Fset, &ast.CallExpr{
				Fun: arg,
			})
			fixes = append(fixes, analysis.SuggestedFix{
				Message: "Call the function",
				TextEdits: []analysis.TextEdit{{
					Pos:     arg.Pos(),
					End:     arg.End(),
					NewText: buf.Bytes(),
				}},
			})
		}

		pass.Report(analysis.Diagnostic{
			Pos:            call.Pos(),
			End:            call.End(),
			Message:        fmt.Sprintf("%s's argument must be a slice; is called with %s", callee.FullName(), typ.String()),
			SuggestedFixes: fixes,
		})
	})
	return nil, nil
}


================================================
FILE: go/analysis/passes/sortslice/analyzer_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sortslice_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/sortslice"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, sortslice.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/sortslice/testdata/src/a/a.go
================================================
package a

import "sort"

// IncorrectSort tries to sort an integer.
func IncorrectSort() {
	i := 5
	sortFn := func(i, j int) bool { return false }
	sort.Slice(i, sortFn)         // want "sort.Slice's argument must be a slice; is called with int"
	sort.SliceStable(i, sortFn)   // want "sort.SliceStable's argument must be a slice; is called with int"
	sort.SliceIsSorted(i, sortFn) // want "sort.SliceIsSorted's argument must be a slice; is called with int"
}

// CorrectSort sorts integers. It should not produce a diagnostic.
func CorrectSort() {
	s := []int{2, 3, 5, 6}
	sortFn := func(i, j int) bool { return s[i] < s[j] }
	sort.Slice(s, sortFn)
	sort.SliceStable(s, sortFn)
	sort.SliceIsSorted(s, sortFn)
}

// CorrectInterface sorts an interface with a slice
// as the concrete type. It should not produce a diagnostic.
func CorrectInterface() {
	var s interface{}
	s = interface{}([]int{2, 1, 0})
	sortFn := func(i, j int) bool { return s.([]int)[i] < s.([]int)[j] }
	sort.Slice(s, sortFn)
	sort.SliceStable(s, sortFn)
	sort.SliceIsSorted(s, sortFn)
}

type slicecompare interface {
	compare(i, j int) bool
}

type intslice []int

func (s intslice) compare(i, j int) bool {
	return s[i] < s[j]
}

// UnderlyingInterface sorts an interface with a slice
// as the concrete type. It should not produce a diagnostic.
func UnderlyingInterface() {
	var s slicecompare
	s = intslice([]int{2, 1, 0})
	sort.Slice(s, s.compare)
	sort.SliceStable(s, s.compare)
	sort.SliceIsSorted(s, s.compare)
}

type mySlice []int

// UnderlyingSlice sorts a type with an underlying type of
// slice of ints. It should not produce a diagnostic.
func UnderlyingSlice() {
	s := mySlice{2, 3, 5, 6}
	sortFn := func(i, j int) bool { return s[i] < s[j] }
	sort.Slice(s, sortFn)
	sort.SliceStable(s, sortFn)
	sort.SliceIsSorted(s, sortFn)
}

// FunctionResultsAsArguments passes a function which returns two values
// that satisfy sort.Slice signature. It should not produce a diagnostic.
func FunctionResultsAsArguments() {
	s := []string{"a", "z", "ooo"}
	sort.Slice(less(s))
	sort.Slice(lessPtr(s)) // want `sort.Slice's argument must be a slice; is called with \(\*\[\]string,.*`
}

func less(s []string) ([]string, func(i, j int) bool) {
	return s, func(i, j int) bool {
		return s[i] < s[j]
	}
}

func lessPtr(s []string) (*[]string, func(i, j int) bool) {
	return &s, func(i, j int) bool {
		return s[i] < s[j]
	}
}


================================================
FILE: go/analysis/passes/stdmethods/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stdmethods defines an Analyzer that checks for misspellings
// in the signatures of methods similar to well-known interfaces.
//
// # Analyzer stdmethods
//
// stdmethods: check signature of methods of well-known interfaces
//
// Sometimes a type may be intended to satisfy an interface but may fail to
// do so because of a mistake in its method signature.
// For example, the result of this WriteTo method should be (int64, error),
// not error, to satisfy io.WriterTo:
//
//	type myWriterTo struct{...}
//	func (myWriterTo) WriteTo(w io.Writer) error { ... }
//
// This check ensures that each method whose name matches one of several
// well-known interface methods from the standard library has the correct
// signature for that interface.
//
// Checked method names include:
//
//	Format GobEncode GobDecode MarshalJSON MarshalXML
//	Peek ReadByte ReadFrom ReadRune Scan Seek
//	UnmarshalJSON UnreadByte UnreadRune WriteByte
//	WriteTo
package stdmethods


================================================
FILE: go/analysis/passes/stdmethods/stdmethods.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stdmethods

import (
	_ "embed"
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "stdmethods",
	Doc:      analyzerutil.MustExtractDoc(doc, "stdmethods"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdmethods",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

// canonicalMethods lists the input and output types for Go methods
// that are checked using dynamic interface checks. Because the
// checks are dynamic, such methods would not cause a compile error
// if they have the wrong signature: instead the dynamic check would
// fail, sometimes mysteriously. If a method is found with a name listed
// here but not the input/output types listed here, vet complains.
//
// A few of the canonical methods have very common names.
// For example, a type might implement a Scan method that
// has nothing to do with fmt.Scanner, but we still want to check
// the methods that are intended to implement fmt.Scanner.
// To do that, the arguments that have a = prefix are treated as
// signals that the canonical meaning is intended: if a Scan
// method doesn't have a fmt.ScanState as its first argument,
// we let it go. But if it does have a fmt.ScanState, then the
// rest has to match.
var canonicalMethods = map[string]struct{ args, results []string }{
	"As": {[]string{"any"}, []string{"bool"}}, // errors.As
	// "Flush": {{}, {"error"}}, // http.Flusher and jpeg.writer conflict
	"Format":        {[]string{"=fmt.State", "rune"}, []string{}},                      // fmt.Formatter
	"GobDecode":     {[]string{"[]byte"}, []string{"error"}},                           // gob.GobDecoder
	"GobEncode":     {[]string{}, []string{"[]byte", "error"}},                         // gob.GobEncoder
	"Is":            {[]string{"error"}, []string{"bool"}},                             // errors.Is
	"MarshalJSON":   {[]string{}, []string{"[]byte", "error"}},                         // json.Marshaler
	"MarshalXML":    {[]string{"*xml.Encoder", "xml.StartElement"}, []string{"error"}}, // xml.Marshaler
	"ReadByte":      {[]string{}, []string{"byte", "error"}},                           // io.ByteReader
	"ReadFrom":      {[]string{"=io.Reader"}, []string{"int64", "error"}},              // io.ReaderFrom
	"ReadRune":      {[]string{}, []string{"rune", "int", "error"}},                    // io.RuneReader
	"Scan":          {[]string{"=fmt.ScanState", "rune"}, []string{"error"}},           // fmt.Scanner
	"Seek":          {[]string{"=int64", "int"}, []string{"int64", "error"}},           // io.Seeker
	"UnmarshalJSON": {[]string{"[]byte"}, []string{"error"}},                           // json.Unmarshaler
	"UnmarshalXML":  {[]string{"*xml.Decoder", "xml.StartElement"}, []string{"error"}}, // xml.Unmarshaler
	"UnreadByte":    {[]string{}, []string{"error"}},
	"UnreadRune":    {[]string{}, []string{"error"}},
	"Unwrap":        {[]string{}, []string{"error"}},                      // errors.Unwrap
	"WriteByte":     {[]string{"byte"}, []string{"error"}},                // jpeg.writer (matching bufio.Writer)
	"WriteTo":       {[]string{"=io.Writer"}, []string{"int64", "error"}}, // io.WriterTo
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.FuncDecl)(nil),
		(*ast.InterfaceType)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.FuncDecl:
			if n.Recv != nil {
				canonicalMethod(pass, n.Name)
			}
		case *ast.InterfaceType:
			for _, field := range n.Methods.List {
				for _, id := range field.Names {
					canonicalMethod(pass, id)
				}
			}
		}
	})
	return nil, nil
}

func canonicalMethod(pass *analysis.Pass, id *ast.Ident) {
	// Expected input/output.
	expect, ok := canonicalMethods[id.Name]
	if !ok {
		return
	}

	// Actual input/output
	sign := pass.TypesInfo.Defs[id].Type().(*types.Signature)
	args := sign.Params()
	results := sign.Results()

	// Special case: WriteTo with more than one argument,
	// not trying at all to implement io.WriterTo,
	// comes up often enough to skip.
	if id.Name == "WriteTo" && args.Len() > 1 {
		return
	}

	// Special case: Is, As and Unwrap only apply when type
	// implements error.
	if id.Name == "Is" || id.Name == "As" || id.Name == "Unwrap" {
		if recv := sign.Recv(); recv == nil || !implementsError(recv.Type()) {
			return
		}
	}

	// Special case: Unwrap has two possible signatures.
	// Check for Unwrap() []error here.
	if id.Name == "Unwrap" {
		if args.Len() == 0 && results.Len() == 1 {
			t := typeString(results.At(0).Type())
			if t == "error" || t == "[]error" {
				return
			}
		}
		pass.ReportRangef(id, "method Unwrap() should have signature Unwrap() error or Unwrap() []error")
		return
	}

	// Do the =s (if any) all match?
	if !matchParams(expect.args, args, "=") || !matchParams(expect.results, results, "=") {
		return
	}

	// Everything must match.
	if !matchParams(expect.args, args, "") || !matchParams(expect.results, results, "") {
		expectFmt := id.Name + "(" + argjoin(expect.args) + ")"
		if len(expect.results) == 1 {
			expectFmt += " " + argjoin(expect.results)
		} else if len(expect.results) > 1 {
			expectFmt += " (" + argjoin(expect.results) + ")"
		}

		actual := typeString(sign)
		actual = strings.TrimPrefix(actual, "func")
		actual = id.Name + actual

		pass.ReportRangef(id, "method %s should have signature %s", actual, expectFmt)
	}
}

func typeString(typ types.Type) string {
	return types.TypeString(typ, (*types.Package).Name)
}

func argjoin(x []string) string {
	y := make([]string, len(x))
	for i, s := range x {
		if s[0] == '=' {
			s = s[1:]
		}
		y[i] = s
	}
	return strings.Join(y, ", ")
}

// Does each type in expect with the given prefix match the corresponding type in actual?
func matchParams(expect []string, actual *types.Tuple, prefix string) bool {
	for i, x := range expect {
		if !strings.HasPrefix(x, prefix) {
			continue
		}
		if i >= actual.Len() {
			return false
		}
		if !matchParamType(x, actual.At(i).Type()) {
			return false
		}
	}
	if prefix == "" && actual.Len() > len(expect) {
		return false
	}
	return true
}

// Does this one type match?
func matchParamType(expect string, actual types.Type) bool {
	expect = strings.TrimPrefix(expect, "=")
	// Overkill but easy.
	t := typeString(actual)
	return t == expect ||
		(t == "any" || t == "interface{}") && (expect == "any" || expect == "interface{}")
}

var errorType = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

func implementsError(actual types.Type) bool {
	return types.Implements(actual, errorType)
}


================================================
FILE: go/analysis/passes/stdmethods/stdmethods_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stdmethods_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/stdmethods"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, stdmethods.Analyzer, "a", "typeparams")
}

func TestAnalyzeEncodingXML(t *testing.T) {
	analysistest.Run(t, "", stdmethods.Analyzer, "encoding/xml")
}


================================================
FILE: go/analysis/passes/stdmethods/testdata/src/a/a.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"encoding/xml"
	"fmt"
	"io"
)

type T int

func (T) Scan(x fmt.ScanState, c byte) {} // want `should have signature Scan\(fmt\.ScanState, rune\) error`

func (T) Format(fmt.State, byte) {} // want `should have signature Format\(fmt.State, rune\)`

type U int

func (U) Format(byte) {} // no error: first parameter must be fmt.State to trigger check

func (U) GobDecode() {} // want `should have signature GobDecode\(\[\]byte\) error`

// Test rendering of type names such as xml.Encoder in diagnostic.
func (U) MarshalXML(*xml.Encoder) {} // want `method MarshalXML\(\*xml.Encoder\) should...`

func (U) UnmarshalXML(*xml.Decoder, xml.StartElement) error { // no error: signature matches xml.Unmarshaler
	return nil
}

func (U) WriteTo(w io.Writer) {} // want `method WriteTo\(w io.Writer\) should have signature WriteTo\(io.Writer\) \(int64, error\)`

func (T) WriteTo(w io.Writer, more, args int) {} // ok - clearly not io.WriterTo

type I interface {
	ReadByte() byte // want `should have signature ReadByte\(\) \(byte, error\)`
}

type V int // V does not implement error.

func (V) As() T       { return 0 }     // ok - V is not an error
func (V) Is() bool    { return false } // ok - V is not an error
func (V) Unwrap() int { return 0 }     // ok - V is not an error

type E int

func (E) Error() string { return "" } // E implements error.

func (E) As()     {} // want `method As\(\) should have signature As\((any|interface\{\})\) bool`
func (E) Is()     {} // want `method Is\(\) should have signature Is\(error\) bool`
func (E) Unwrap() {} // want `method Unwrap\(\) should have signature Unwrap\(\) error or Unwrap\(\) \[\]error`

type F int

func (F) Error() string { return "" } // Both F and *F implement error.

func (*F) As()     {} // want `method As\(\) should have signature As\((any|interface\{\})\) bool`
func (*F) Is()     {} // want `method Is\(\) should have signature Is\(error\) bool`
func (*F) Unwrap() {} // want `method Unwrap\(\) should have signature Unwrap\(\) error or Unwrap\(\) \[\]error`

type G int

func (G) As(interface{}) bool // ok

type W int

func (W) Error() string { return "" }
func (W) Unwrap() error { return nil } // ok

type M int

func (M) Error() string   { return "" }
func (M) Unwrap() []error { return nil } // ok


================================================
FILE: go/analysis/passes/stdmethods/testdata/src/a/b.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

type H int

func (H) As(any) bool // ok


================================================
FILE: go/analysis/passes/stdmethods/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "fmt"

type T[P any] int

func (T[_]) Scan(x fmt.ScanState, c byte) {} // want `should have signature Scan\(fmt\.ScanState, rune\) error`

func (T[_]) Format(fmt.State, byte) {} // want `should have signature Format\(fmt.State, rune\)`

type U[P any] int

func (U[_]) Format(byte) {} // no error: first parameter must be fmt.State to trigger check

func (U[P]) GobDecode(P) {} // want `should have signature GobDecode\(\[\]byte\) error`

type V[P any] int // V does not implement error.

func (V[_]) As() T[int]  { return 0 }     // ok - V is not an error
func (V[_]) Is() bool    { return false } // ok - V is not an error
func (V[_]) Unwrap() int { return 0 }     // ok - V is not an error

type E[P any] int

func (E[_]) Error() string { return "" } // E implements error.

func (E[P]) As()     {} // want `method As\(\) should have signature As\((any|interface\{\})\) bool`
func (E[_]) Is()     {} // want `method Is\(\) should have signature Is\(error\) bool`
func (E[_]) Unwrap() {} // want `method Unwrap\(\) should have signature Unwrap\(\) error or Unwrap\(\) \[\]error`

type F[P any] int

func (F[_]) Error() string { return "" } // Both F and *F implement error.

func (*F[_]) As()     {} // want `method As\(\) should have signature As\((any|interface\{\})\) bool`
func (*F[_]) Is()     {} // want `method Is\(\) should have signature Is\(error\) bool`
func (*F[_]) Unwrap() {} // want `method Unwrap\(\) should have signature Unwrap\(\) error or Unwrap\(\) \[\]error`


================================================
FILE: go/analysis/passes/stdversion/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

package main

import (
	"golang.org/x/tools/go/analysis/passes/stdversion"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(stdversion.Analyzer) }


================================================
FILE: go/analysis/passes/stdversion/stdversion.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stdversion reports uses of standard library symbols that are
// "too new" for the Go version in force in the referring file.
package stdversion

import (
	"go/ast"
	"go/build"
	"go/types"
	"slices"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

const Doc = `report uses of too-new standard library symbols

The stdversion analyzer reports references to symbols in the standard
library that were introduced by a Go release higher than the one in
force in the referring file. (Recall that the file's Go version is
defined by the 'go' directive its module's go.mod file, or by a
"//go:build go1.X" build tag at the top of the file.)

The analyzer does not report a diagnostic for a reference to a "too
new" field or method of a type that is itself "too new", as this may
have false positives, for example if fields or methods are accessed
through a type alias that is guarded by a Go version constraint.
`

var Analyzer = &analysis.Analyzer{
	Name:             "stdversion",
	Doc:              Doc,
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdversion",
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	// Prior to go1.22, versions.FileVersion returns only the
	// toolchain version, which is of no use to us, so
	// disable this analyzer on earlier versions.
	if !slices.Contains(build.Default.ReleaseTags, "go1.22") {
		return nil, nil
	}

	// Don't report diagnostics for modules marked before go1.21,
	// since at that time the go directive wasn't clearly
	// specified as a toolchain requirement.
	pkgVersion := pass.Pkg.GoVersion()
	if !versions.AtLeast(pkgVersion, "go1.21") {
		return nil, nil
	}

	// disallowedSymbols returns the set of standard library symbols
	// in a given package that are disallowed at the specified Go version.
	type key struct {
		pkg     *types.Package
		version string
	}
	memo := make(map[key]map[types.Object]string) // records symbol's minimum Go version
	disallowedSymbols := func(pkg *types.Package, version string) map[types.Object]string {
		k := key{pkg, version}
		disallowed, ok := memo[k]
		if !ok {
			disallowed = typesinternal.TooNewStdSymbols(pkg, version)
			memo[k] = disallowed
		}
		return disallowed
	}

	// Scan the syntax looking for references to symbols
	// that are disallowed by the version of the file.
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.File)(nil),
		(*ast.Ident)(nil),
	}
	var fileVersion string // "" => no check
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.File:
			if ast.IsGenerated(n) {
				// Suppress diagnostics in generated files (such as cgo).
				fileVersion = ""
			} else {
				fileVersion = versions.Lang(versions.FileVersion(pass.TypesInfo, n))
				// (may be "" if unknown)
			}

		case *ast.Ident:
			if fileVersion != "" {
				if obj, ok := pass.TypesInfo.Uses[n]; ok && obj.Pkg() != nil {
					disallowed := disallowedSymbols(obj.Pkg(), fileVersion)
					if minVersion, ok := disallowed[origin(obj)]; ok {
						// Some symbols are accessible before their release but
						// only with specific build tags unknown to us here.
						// Avoid false positives in such cases.
						// TODO(mkalil): move this check into typesinternal.TooNewStdSymbols.
						if obj.Pkg().Path() == "testing/synctest" && versions.AtLeast(fileVersion, "go1.24") {
							break // requires go1.24 && goexperiment.synctest || go1.25
						}
						noun := "module"
						if fileVersion != pkgVersion {
							noun = "file"
						}
						pass.ReportRangef(n, "%s.%s requires %v or later (%s is %s)",
							obj.Pkg().Name(), obj.Name(), minVersion, noun, fileVersion)
					}
				}
			}
		}
	})
	return nil, nil
}

// origin returns the original uninstantiated symbol for obj.
func origin(obj types.Object) types.Object {
	switch obj := obj.(type) {
	case *types.Var:
		return obj.Origin()
	case *types.Func:
		return obj.Origin()
	case *types.TypeName:
		if named, ok := obj.Type().(*types.Named); ok { // (don't unalias)
			return named.Origin().Obj()
		}
	}
	return obj
}


================================================
FILE: go/analysis/passes/stdversion/stdversion_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stdversion_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/stdversion"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
)

func Test(t *testing.T) {
	testenv.NeedsGo1Point(t, 23) // TODO(#68658): Waiting on 1.22 backport.

	// The test relies on go1.21 std symbols, but the analyzer
	// itself requires the go1.22 implementation of versions.FileVersions.
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "test.txtar"))
	analysistest.Run(t, dir, stdversion.Analyzer,
		"example.com/basic",
		"example.com/despite",
		"example.com/mod20",
		"example.com/mod21",
		"example.com/mod22",
		"example.com/old",
	)
}


================================================
FILE: go/analysis/passes/stdversion/testdata/test.txtar
================================================
Test of "too new" diagnostics from the stdversion analyzer.

This test references go1.21 and go1.22 symbols from std.

See also gopls/internal/test/marker/testdata/diagnostics/stdversion.txt
which runs the same test within the gopls analysis driver, to ensure
coverage of per-file Go version support.

-- go.work --
go 1.22

use .
use mod20
use mod21
use mod22
use old

-- go.mod --
module example.com

go 1.21

-- basic/basic.go --
// File version is 1.21.
package basic

import "go/types"

func _() {
	// old package-level type
	var _ types.Info // ok: defined by go1.0

	// new field of older type
	_ = new(types.Info).FileVersions // want `types.FileVersions requires go1.22 or later \(module is go1.21\)`

	// new method of older type
	new(types.Info).PkgNameOf // want `types.PkgNameOf requires go1.22 or later \(module is go1.21\)`

	// new package-level type
	var a types.Alias // want `types.Alias requires go1.22 or later \(module is go1.21\)`

	// new method of new type
	a.Underlying() // no diagnostic
}

-- despite/errors.go --
// File version is 1.21.

// Check that RunDespiteErrors is enabled.
package ignore

import "go/types"

func _() {
	// report something before the syntax error.
	_ = new(types.Info).FileVersions // want `types.FileVersions requires go1.22 or later \(module is go1.21\)`
}

invalid syntax // exercise RunDespiteErrors

-- mod20/go.mod --
module example.com/mod20

go 1.20

-- mod20/notag.go --
// The 1.20 module is before the forward compatibility regime:
// The file's build tag effects selection, but
// not language semantics, so stdversion is silent.

package mod20

import "go/types"

func _() {
	var _ types.Alias
}

-- mod20/tag16.go --
// The 1.20 module is before the forward compatibility regime:
// The file's build tag effects selection, but
// not language semantics, so stdversion is silent.

//go:build go1.16

package mod20

import "bytes"
import "go/types"

var _ = bytes.Clone
var _ = types.Alias

-- mod20/tag22.go --
// The 1.20 module is before the forward compatibility regime:
// The file's build tag effects selection, but
// not language semantics, so stdversion is silent.

//go:build go1.22

package mod20

import "bytes"
import "go/types"

var _ = bytes.Clone
var _ = types.Alias

-- mod21/go.mod --
module example.com/mod21

go 1.21

-- mod21/notag.go --
// File version is 1.21.
package mod21

import "go/types"

func _() {
	// old package-level type
	var _ types.Info // ok: defined by go1.0

	// new field of older type
	_ = new(types.Info).FileVersions // want `types.FileVersions requires go1.22 or later \(module is go1.21\)`

	// new method of older type
	new(types.Info).PkgNameOf // want `types.PkgNameOf requires go1.22 or later \(module is go1.21\)`

	// new package-level type
	var a types.Alias // want `types.Alias requires go1.22 or later \(module is go1.21\)`

	// new method of new type
	a.Underlying() // no diagnostic
}

-- mod21/tag16.go --
// File version is 1.21.
//
// The module is within the forward compatibility regime so
// the build tag (1.16) can modify the file version, but it cannot
// go below the 1.21 "event horizon" (#68658).

//go:build go1.16

package mod21

import "bytes"
import "go/types"

var _ = bytes.Clone
var _ = types.Alias // want `types.Alias requires go1.22 or later \(module is go1.21\)`

-- mod21/tag22.go --
// File version is 1.22.
//
// The module is within the forward compatibility regime so
// the build tag (1.22) updates the file version to 1.22.

//go:build go1.22

package mod21

import "bytes"
import "go/types"

var _ = bytes.Clone
var _ = types.Alias 

-- mod22/go.mod --
module example.com/mod22

go 1.22

-- mod22/notag.go --
// File version is 1.22.
package mod22

import "go/types"

func _() {
	var _ = bytes.Clone
	var _ = types.Alias
}

-- mod22/tag16.go --
// File version is 1.21.
//
// The module is within the forward compatibility regime so
// the build tag (1.16) can modify the file version, but it cannot
// go below the 1.21 "event horizon" (#68658).

//go:build go1.16

package mod22

import "bytes"
import "go/types"

var _ = bytes.Clone
var _ = types.Alias // want `types.Alias requires go1.22 or later \(file is go1.21\)`

-- old/go.mod --
module example.com/old

go 1.5

-- old/notag.go --
package old

import "go/types"

var _ types.Alias // no diagnostic: go.mod is too old for us to care

-- old/tag21.go --
// The build tag is ignored due to the module version.

//go:build go1.21

package old

import "go/types"

var _ = types.Alias // no diagnostic: go.mod is too old for us to care


================================================
FILE: go/analysis/passes/stringintconv/cmd/stringintconv/main.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The stringintconv command runs the stringintconv analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/stringintconv"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(stringintconv.Analyzer) }


================================================
FILE: go/analysis/passes/stringintconv/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stringintconv defines an Analyzer that flags type conversions
// from integers to strings.
//
// # Analyzer stringintconv
//
// stringintconv: check for string(int) conversions
//
// This checker flags conversions of the form string(x) where x is an integer
// (but not byte or rune) type. Such conversions are discouraged because they
// return the UTF-8 representation of the Unicode code point x, and not a decimal
// string representation of x as one might expect. Furthermore, if x denotes an
// invalid code point, the conversion cannot be statically rejected.
//
// For conversions that intend on using the code point, consider replacing them
// with string(rune(x)). Otherwise, strconv.Itoa and its equivalents return the
// string representation of the value in the desired base.
package stringintconv


================================================
FILE: go/analysis/passes/stringintconv/string.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stringintconv

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "stringintconv",
	Doc:      analyzerutil.MustExtractDoc(doc, "stringintconv"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stringintconv",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

// describe returns a string describing the type typ contained within the type
// set of inType. If non-empty, inName is used as the name of inType (this is
// necessary so that we can use alias type names that may not be reachable from
// inType itself).
func describe(typ, inType types.Type, inName string) string {
	name := inName
	if typ != inType {
		name = typeName(typ)
	}
	if name == "" {
		return ""
	}

	var parentheticals []string
	if underName := typeName(typ.Underlying()); underName != "" && underName != name {
		parentheticals = append(parentheticals, underName)
	}

	if typ != inType && inName != "" && inName != name {
		parentheticals = append(parentheticals, "in "+inName)
	}

	if len(parentheticals) > 0 {
		name += " (" + strings.Join(parentheticals, ", ") + ")"
	}

	return name
}

func typeName(t types.Type) string {
	if basic, ok := t.(*types.Basic); ok {
		return basic.Name() // may be (e.g.) "untyped int", which has no TypeName
	}
	if tname := typesinternal.TypeNameFor(t); tname != nil {
		return tname.Name()
	}
	return ""
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.File)(nil),
		(*ast.CallExpr)(nil),
	}
	var file *ast.File
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		if n, ok := n.(*ast.File); ok {
			file = n
			return
		}
		call := n.(*ast.CallExpr)

		if len(call.Args) != 1 {
			return
		}
		arg := call.Args[0]

		// Retrieve target type name.
		var tname *types.TypeName
		switch fun := call.Fun.(type) {
		case *ast.Ident:
			tname, _ = pass.TypesInfo.Uses[fun].(*types.TypeName)
		case *ast.SelectorExpr:
			tname, _ = pass.TypesInfo.Uses[fun.Sel].(*types.TypeName)
		}
		if tname == nil {
			return
		}

		// In the conversion T(v) of a value v of type V to a target type T, we
		// look for types T0 in the type set of T and V0 in the type set of V, such
		// that V0->T0 is a problematic conversion. If T and V are not type
		// parameters, this amounts to just checking if V->T is a problematic
		// conversion.

		// First, find a type T0 in T that has an underlying type of string.
		T := tname.Type()
		ttypes, err := structuralTypes(T)
		if err != nil {
			return // invalid type
		}

		var T0 types.Type // string type in the type set of T

		for _, tt := range ttypes {
			u, _ := tt.Underlying().(*types.Basic)
			if u != nil && u.Kind() == types.String {
				T0 = tt
				break
			}
		}

		if T0 == nil {
			// No target types have an underlying type of string.
			return
		}

		// Next, find a type V0 in V that has an underlying integral type that is
		// not byte or rune.
		V := pass.TypesInfo.TypeOf(arg)
		vtypes, err := structuralTypes(V)
		if err != nil {
			return // invalid type
		}

		var V0 types.Type // integral type in the type set of V

		for _, vt := range vtypes {
			u, _ := vt.Underlying().(*types.Basic)
			if u != nil && u.Info()&types.IsInteger != 0 {
				switch u.Kind() {
				case types.Byte, types.Rune, types.UntypedRune:
					continue
				}
				V0 = vt
				break
			}
		}

		if V0 == nil {
			// No source types are non-byte or rune integer types.
			return
		}

		convertibleToRune := true // if true, we can suggest a fix
		for _, t := range vtypes {
			if !types.ConvertibleTo(t, types.Typ[types.Rune]) {
				convertibleToRune = false
				break
			}
		}

		target := describe(T0, T, tname.Name())
		source := describe(V0, V, typeName(V))

		if target == "" || source == "" {
			return // something went wrong
		}

		diag := analysis.Diagnostic{
			Pos:     n.Pos(),
			Message: fmt.Sprintf("conversion from %s to %s yields a string of one rune, not a string of digits", source, target),
		}
		addFix := func(message string, edits []analysis.TextEdit) {
			diag.SuggestedFixes = append(diag.SuggestedFixes, analysis.SuggestedFix{
				Message:   message,
				TextEdits: edits,
			})
		}

		// Fix 1: use fmt.Sprint(x)
		//
		// Prefer fmt.Sprint over strconv.Itoa, FormatInt,
		// or FormatUint, as it works for any type.
		// Add an import of "fmt" as needed.
		//
		// Unless the type is exactly string, we must retain the conversion.
		//
		// Do not offer this fix if type parameters are involved,
		// as there are too many combinations and subtleties.
		// Consider x = rune | int16 | []byte: in all cases,
		// string(x) is legal, but the appropriate diagnostic
		// and fix differs. Similarly, don't offer the fix if
		// the type has methods, as some {String,GoString,Format}
		// may change the behavior of fmt.Sprint.
		if len(ttypes) == 1 && len(vtypes) == 1 && types.NewMethodSet(V0).Len() == 0 {
			prefix, importEdits := refactor.AddImport(pass.TypesInfo, file, "fmt", "fmt", "Sprint", arg.Pos())
			if types.Identical(T0, types.Typ[types.String]) {
				// string(x) -> fmt.Sprint(x)
				addFix("Format the number as a decimal", append(importEdits,
					analysis.TextEdit{
						Pos:     call.Fun.Pos(),
						End:     call.Fun.End(),
						NewText: []byte(prefix + "Sprint"),
					}),
				)
			} else {
				// mystring(x) -> mystring(fmt.Sprint(x))
				addFix("Format the number as a decimal", append(importEdits,
					analysis.TextEdit{
						Pos:     call.Lparen + 1,
						End:     call.Lparen + 1,
						NewText: []byte(prefix + "Sprint("),
					},
					analysis.TextEdit{
						Pos:     call.Rparen,
						End:     call.Rparen,
						NewText: []byte(")"),
					}),
				)
			}
		}

		// Fix 2: use string(rune(x))
		if convertibleToRune {
			addFix("Convert a single rune to a string", []analysis.TextEdit{
				{
					Pos:     arg.Pos(),
					End:     arg.Pos(),
					NewText: []byte("rune("),
				},
				{
					Pos:     arg.End(),
					End:     arg.End(),
					NewText: []byte(")"),
				},
			})
		}
		pass.Report(diag)
	})
	return nil, nil
}

func structuralTypes(t types.Type) ([]types.Type, error) {
	var structuralTypes []types.Type
	if tp, ok := types.Unalias(t).(*types.TypeParam); ok {
		terms, err := typeparams.StructuralTerms(tp)
		if err != nil {
			return nil, err
		}
		for _, term := range terms {
			structuralTypes = append(structuralTypes, term.Type())
		}
	} else {
		structuralTypes = append(structuralTypes, t)
	}
	return structuralTypes, nil
}


================================================
FILE: go/analysis/passes/stringintconv/string_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stringintconv_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/stringintconv"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, stringintconv.Analyzer, "a", "typeparams")
	analysistest.RunWithSuggestedFixes(t, testdata, stringintconv.Analyzer, "fix")
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the stringintconv checker.

package a

type A string

type B = string

type C int

type D = uintptr

func StringTest() {
	var (
		i int
		j rune
		k byte
		l C
		m D
		n = []int{0, 1, 2}
		o struct{ x int }
	)
	const p = 0
	// First time only, assert the complete message:
	_ = string(i) // want `^conversion from int to string yields a string of one rune, not a string of digits$`
	_ = string(j)
	_ = string(k)
	_ = string(p)    // want `...from untyped int to string...`
	_ = A(l)         // want `...from C \(int\) to A \(string\)...`
	_ = B(m)         // want `...from (uintptr|D \(uintptr\)) to B \(string\)...`
	_ = string(n[1]) // want `...from int to string...`
	_ = string(o.x)  // want `...from int to string...`
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fix.go
================================================
package fix

func _(x uint64) {
	println(string(x)) // want `conversion from uint64 to string yields...`
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fix.go.golden
================================================
-- Format the number as a decimal --
package fix

import "fmt"

func _(x uint64) {
     println(fmt.Sprint(x)) // want `conversion from uint64 to string yields...`
}

-- Convert a single rune to a string --
package fix

func _(x uint64) {
     println(string(rune(x))) // want `conversion from uint64 to string yields...`
}



================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fixdot.go
================================================
package fix

import . "fmt"

func _(x uint64) {
	Println(string(x)) // want `conversion from uint64 to string yields...`
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fixdot.go.golden
================================================
-- Format the number as a decimal --
package fix

import . "fmt"

func _(x uint64) {
     Println(Sprint(x)) // want `conversion from uint64 to string yields...`
}

-- Convert a single rune to a string --
package fix

import . "fmt"

func _(x uint64) {
     Println(string(rune(x))) // want `conversion from uint64 to string yields...`
}



================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fixnamed.go
================================================
package fix

type mystring string

func _(x int16) mystring {
	return mystring(x) // want `conversion from int16 to mystring \(string\)...`
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/fix/fixnamed.go.golden
================================================
-- Format the number as a decimal --
package fix

import "fmt"

type mystring string

func _(x int16) mystring {
	return mystring(fmt.Sprint(x)) // want `conversion from int16 to mystring \(string\)...`
}

-- Convert a single rune to a string --
package fix

type mystring string

func _(x int16) mystring {
	return mystring(rune(x)) // want `conversion from int16 to mystring \(string\)...`
}


================================================
FILE: go/analysis/passes/stringintconv/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

type (
	Int     int
	Uintptr = uintptr
	String  string
)

func _[AllString ~string, MaybeString ~string | ~int, NotString ~int | byte, NamedString String | Int]() {
	var (
		i int
		r rune
		b byte
		I Int
		U uintptr
		M MaybeString
		N NotString
	)
	const p = 0

	_ = MaybeString(i) // want `conversion from int to string .in MaybeString. yields a string of one rune, not a string of digits`
	_ = MaybeString(r)
	_ = MaybeString(b)
	_ = MaybeString(I) // want `conversion from Int .int. to string .in MaybeString. yields a string of one rune, not a string of digits`
	_ = MaybeString(U) // want `conversion from uintptr to string .in MaybeString. yields a string of one rune, not a string of digits`
	// Type parameters are never constant types, so arguments are always
	// converted to their default type (int versus untyped int, in this case)
	_ = MaybeString(p) // want `conversion from int to string .in MaybeString. yields a string of one rune, not a string of digits`
	// ...even if the type parameter is only strings.
	_ = AllString(p) // want `conversion from int to string .in AllString. yields a string of one rune, not a string of digits`

	_ = NotString(i)
	_ = NotString(r)
	_ = NotString(b)
	_ = NotString(I)
	_ = NotString(U)
	_ = NotString(p)

	_ = NamedString(i) // want `conversion from int to String .string, in NamedString. yields a string of one rune, not a string of digits`
	_ = string(M)      // want `conversion from int .in MaybeString. to string yields a string of one rune, not a string of digits`

	// Note that M is not convertible to rune.
	_ = MaybeString(M) // want `conversion from int .in MaybeString. to string .in MaybeString. yields a string of one rune, not a string of digits`
	_ = NotString(N)   // ok
}


================================================
FILE: go/analysis/passes/structtag/structtag.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package structtag defines an Analyzer that checks struct field tags
// are well formed.
package structtag

import (
	"errors"
	"go/ast"
	"go/token"
	"go/types"
	"path/filepath"
	"reflect"
	"slices"
	"strconv"
	"strings"

	"fmt"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
)

const Doc = `check that struct field tags conform to reflect.StructTag.Get

Also report certain struct tags (json, xml) used with unexported fields.`

var Analyzer = &analysis.Analyzer{
	Name:             "structtag",
	Doc:              Doc,
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/structtag",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.StructType)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		styp, ok := pass.TypesInfo.Types[n.(*ast.StructType)].Type.(*types.Struct)
		// Type information may be incomplete.
		if !ok {
			return
		}
		var seen namesSeen
		for i := 0; i < styp.NumFields(); i++ {
			field := styp.Field(i)
			tag := styp.Tag(i)
			checkCanonicalFieldTag(pass, field, tag, &seen)
		}
	})
	return nil, nil
}

// namesSeen keeps track of encoding tags by their key, name, and nested level
// from the initial struct. The level is taken into account because equal
// encoding key names only conflict when at the same level; otherwise, the lower
// level shadows the higher level.
type namesSeen map[uniqueName]token.Pos

type uniqueName struct {
	key   string // "xml" or "json"
	name  string // the encoding name
	level int    // anonymous struct nesting level
}

func (s *namesSeen) Get(key, name string, level int) (token.Pos, bool) {
	if *s == nil {
		*s = make(map[uniqueName]token.Pos)
	}
	pos, ok := (*s)[uniqueName{key, name, level}]
	return pos, ok
}

func (s *namesSeen) Set(key, name string, level int, pos token.Pos) {
	if *s == nil {
		*s = make(map[uniqueName]token.Pos)
	}
	(*s)[uniqueName{key, name, level}] = pos
}

var checkTagDups = []string{"json", "xml"}
var checkTagSpaces = map[string]bool{"json": true, "xml": true, "asn1": true}

// checkCanonicalFieldTag checks a single struct field tag.
func checkCanonicalFieldTag(pass *analysis.Pass, field *types.Var, tag string, seen *namesSeen) {
	if strings.HasPrefix(pass.Pkg.Path(), "encoding/") {
		// These packages know how to use their own APIs.
		// Sometimes they are testing what happens to incorrect programs.
		return
	}

	for _, key := range checkTagDups {
		checkTagDuplicates(pass, tag, key, field, field, seen, 1)
	}

	if err := validateStructTag(tag); err != nil {
		pass.Report(analysis.Diagnostic{
			Pos:     field.Pos(),
			End:     field.Pos() + token.Pos(len(field.Name())),
			Message: fmt.Sprintf("struct field tag %#q not compatible with reflect.StructTag.Get: %s", tag, err),
		})
	}

	// Check for use of json or xml tags with unexported fields.

	// Embedded struct. Nothing to do for now, but that
	// may change, depending on what happens with issue 7363.
	// TODO(adonovan): investigate, now that issue is fixed.
	if field.Anonymous() {
		return
	}

	if field.Exported() {
		return
	}

	for _, enc := range [...]string{"json", "xml"} {
		switch reflect.StructTag(tag).Get(enc) {
		// Ignore warning if the field not exported and the tag is marked as
		// ignored.
		case "", "-":
		default:
			pass.Report(analysis.Diagnostic{
				Pos:     field.Pos(),
				End:     field.Pos() + token.Pos(len(field.Name())),
				Message: fmt.Sprintf("struct field %s has %s tag but is not exported", field.Name(), enc),
			})
			return
		}
	}
}

// checkTagDuplicates checks a single struct field tag to see if any tags are
// duplicated. nearest is the field that's closest to the field being checked,
// while still being part of the top-level struct type.
func checkTagDuplicates(pass *analysis.Pass, tag, key string, nearest, field *types.Var, seen *namesSeen, level int) {
	val := reflect.StructTag(tag).Get(key)
	if val == "-" {
		// Ignored, even if the field is anonymous.
		return
	}
	if val == "" || val[0] == ',' {
		if !field.Anonymous() {
			// Ignored if the field isn't anonymous.
			return
		}
		typ, ok := field.Type().Underlying().(*types.Struct)
		if !ok {
			return
		}
		for i := 0; i < typ.NumFields(); i++ {
			field := typ.Field(i)
			if !field.Exported() {
				continue
			}
			tag := typ.Tag(i)
			checkTagDuplicates(pass, tag, key, nearest, field, seen, level+1)
		}
		return
	}
	if key == "xml" && field.Name() == "XMLName" {
		// XMLName defines the XML element name of the struct being
		// checked. That name cannot collide with element or attribute
		// names defined on other fields of the struct. Vet does not have a
		// check for untagged fields of type struct defining their own name
		// by containing a field named XMLName; see issue 18256.
		return
	}
	if i := strings.Index(val, ","); i >= 0 {
		if key == "xml" {
			// Use a separate namespace for XML attributes.
			if slices.Contains(strings.Split(val[i:], ","), "attr") {
				key += " attribute" // Key is part of the error message.
			}
		}
		val = val[:i]
	}
	if pos, ok := seen.Get(key, val, level); ok {
		alsoPos := pass.Fset.Position(pos)
		alsoPos.Column = 0

		// Make the "also at" position relative to the current position,
		// to ensure that all warnings are unambiguous and correct. For
		// example, via anonymous struct fields, it's possible for the
		// two fields to be in different packages and directories.
		thisPos := pass.Fset.Position(field.Pos())
		rel, err := filepath.Rel(filepath.Dir(thisPos.Filename), alsoPos.Filename)
		if err != nil {
			// Possibly because the paths are relative; leave the
			// filename alone.
		} else {
			alsoPos.Filename = rel
		}

		pass.Report(analysis.Diagnostic{
			Pos:     nearest.Pos(),
			End:     nearest.Pos() + token.Pos(len(nearest.Name())),
			Message: fmt.Sprintf("struct field %s repeats %s tag %q also at %s", field.Name(), key, val, alsoPos),
		})
	} else {
		seen.Set(key, val, level, field.Pos())
	}
}

var (
	errTagSyntax      = errors.New("bad syntax for struct tag pair")
	errTagKeySyntax   = errors.New("bad syntax for struct tag key")
	errTagValueSyntax = errors.New("bad syntax for struct tag value")
	errTagValueSpace  = errors.New("suspicious space in struct tag value")
	errTagSpace       = errors.New("key:\"value\" pairs not separated by spaces")
)

// validateStructTag parses the struct tag and returns an error if it is not
// in the canonical format, which is a space-separated list of key:"value"
// settings. The value may contain spaces.
func validateStructTag(tag string) error {
	// This code is based on the StructTag.Get code in package reflect.

	n := 0
	for ; tag != ""; n++ {
		if n > 0 && tag != "" && tag[0] != ' ' {
			// More restrictive than reflect, but catches likely mistakes
			// like `x:"foo",y:"bar"`, which parses as `x:"foo" ,y:"bar"` with second key ",y".
			return errTagSpace
		}
		// Skip leading space.
		i := 0
		for i < len(tag) && tag[i] == ' ' {
			i++
		}
		tag = tag[i:]
		if tag == "" {
			break
		}

		// Scan to colon. A space, a quote or a control character is a syntax error.
		// Strictly speaking, control chars include the range [0x7f, 0x9f], not just
		// [0x00, 0x1f], but in practice, we ignore the multi-byte control characters
		// as it is simpler to inspect the tag's bytes than the tag's runes.
		i = 0
		for i < len(tag) && tag[i] > ' ' && tag[i] != ':' && tag[i] != '"' && tag[i] != 0x7f {
			i++
		}
		if i == 0 {
			return errTagKeySyntax
		}
		if i+1 >= len(tag) || tag[i] != ':' {
			return errTagSyntax
		}
		if tag[i+1] != '"' {
			return errTagValueSyntax
		}
		key := tag[:i]
		tag = tag[i+1:]

		// Scan quoted string to find value.
		i = 1
		for i < len(tag) && tag[i] != '"' {
			if tag[i] == '\\' {
				i++
			}
			i++
		}
		if i >= len(tag) {
			return errTagValueSyntax
		}
		qvalue := tag[:i+1]
		tag = tag[i+1:]

		value, err := strconv.Unquote(qvalue)
		if err != nil {
			return errTagValueSyntax
		}

		if !checkTagSpaces[key] {
			continue
		}

		switch key {
		case "xml":
			// If the first or last character in the XML tag is a space, it is
			// suspicious.
			if strings.Trim(value, " ") != value {
				return errTagValueSpace
			}

			// If there are multiple spaces, they are suspicious.
			if strings.Count(value, " ") > 1 {
				return errTagValueSpace
			}

			// If there is no comma, skip the rest of the checks.
			comma := strings.IndexRune(value, ',')
			if comma < 0 {
				continue
			}

			// If the character before a comma is a space, this is suspicious.
			if comma > 0 && value[comma-1] == ' ' {
				return errTagValueSpace
			}
			value = value[comma+1:]
		case "json":
			// JSON allows using spaces in the name, so skip it.
			comma := strings.IndexRune(value, ',')
			if comma < 0 {
				continue
			}
			value = value[comma+1:]
		}

		if strings.IndexByte(value, ' ') >= 0 {
			return errTagValueSpace
		}
	}
	return nil
}


================================================
FILE: go/analysis/passes/structtag/structtag_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package structtag_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/structtag"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, structtag.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/structtag/testdata/src/a/a.go
================================================
// Copyright 2010 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the test for canonical struct tags.

package a

import (
	"a/b"
	"encoding/xml"
)

type StructTagTest struct {
	A   int "hello"            // want "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
	B   int "\tx:\"y\""        // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
	C   int "x:\"y\"\tx:\"y\"" // want "not compatible with reflect.StructTag.Get"
	D   int "x:`y`"            // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
	E   int "ct\brl:\"char\""  // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
	F   int `:"emptykey"`      // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag key"
	G   int `x:"noEndQuote`    // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
	H   int `x:"trunc\x0"`     // want "not compatible with reflect.StructTag.Get: bad syntax for struct tag value"
	I   int `x:"foo",y:"bar"`  // want "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
	J   int `x:"foo"y:"bar"`   // want "not compatible with reflect.StructTag.Get: key:.value. pairs not separated by spaces"
	OK0 int `x:"y" u:"v" w:""`
	OK1 int `x:"y:z" u:"v" w:""` // note multiple colons.
	OK2 int "k0:\"values contain spaces\" k1:\"literal\ttabs\" k2:\"and\\tescaped\\tabs\""
	OK3 int `under_scores:"and" CAPS:"ARE_OK"`
}

type UnexportedEncodingTagTest struct {
	x int `json:"xx"` // want "struct field x has json tag but is not exported"
	y int `xml:"yy"`  // want "struct field y has xml tag but is not exported"
	z int
	A int `json:"aa" xml:"bb"`
	b int `json:"-"`
	C int `json:"-"`
}

type unexp struct{}

type JSONEmbeddedField struct {
	UnexportedEncodingTagTest `is:"embedded"`
	unexp                     `is:"embedded,notexported" json:"unexp"` // OK for now, see issue 7363
}

type AnonymousJSON struct{}
type AnonymousXML struct{}

type AnonymousJSONField struct {
	DuplicateAnonJSON int `json:"a"`

	A int "hello" // want "`hello` not compatible with reflect.StructTag.Get: bad syntax for struct tag pair"
}

// With different names to allow using as anonymous fields multiple times.

type AnonymousJSONField2 struct {
	DuplicateAnonJSON int `json:"a"`
}
type AnonymousJSONField3 struct {
	DuplicateAnonJSON int `json:"a"`
}

type DuplicateJSONFields struct {
	JSON              int `json:"a"`
	DuplicateJSON     int `json:"a"` // want "struct field DuplicateJSON repeats json tag .a. also at a.go:66"
	IgnoredJSON       int `json:"-"`
	OtherIgnoredJSON  int `json:"-"`
	OmitJSON          int `json:",omitempty"`
	OtherOmitJSON     int `json:",omitempty"`
	DuplicateOmitJSON int `json:"a,omitempty"` // want "struct field DuplicateOmitJSON repeats json tag .a. also at a.go:66"
	NonJSON           int `foo:"a"`
	DuplicateNonJSON  int `foo:"a"`
	Embedded          struct {
		DuplicateJSON int `json:"a"` // OK because it's not in the same struct type
	}
	AnonymousJSON `json:"a"` // want "struct field AnonymousJSON repeats json tag .a. also at a.go:66"

	XML              int `xml:"a"`
	DuplicateXML     int `xml:"a"` // want "struct field DuplicateXML repeats xml tag .a. also at a.go:80"
	IgnoredXML       int `xml:"-"`
	OtherIgnoredXML  int `xml:"-"`
	OmitXML          int `xml:",omitempty"`
	OtherOmitXML     int `xml:",omitempty"`
	DuplicateOmitXML int `xml:"a,omitempty"` // want "struct field DuplicateOmitXML repeats xml tag .a. also at a.go:80"
	NonXML           int `foo:"a"`
	DuplicateNonXML  int `foo:"a"`
	Embedded2        struct {
		DuplicateXML int `xml:"a"` // OK because it's not in the same struct type
	}
	AnonymousXML `xml:"a"` // want "struct field AnonymousXML repeats xml tag .a. also at a.go:80"
	Attribute    struct {
		XMLName     xml.Name `xml:"b"`
		NoDup       int      `xml:"b"`                // OK because XMLName above affects enclosing struct.
		Attr        int      `xml:"b,attr"`           // OK because <b b="0"><b>0</b></b> is valid.
		DupAttr     int      `xml:"b,attr"`           // want "struct field DupAttr repeats xml attribute tag .b. also at a.go:96"
		DupOmitAttr int      `xml:"b,omitempty,attr"` // want "struct field DupOmitAttr repeats xml attribute tag .b. also at a.go:96"

		AnonymousXML `xml:"b,attr"` // want "struct field AnonymousXML repeats xml attribute tag .b. also at a.go:96"
	}

	AnonymousJSONField2 `json:"not_anon"` // ok; fields aren't embedded in JSON
	AnonymousJSONField3 `json:"-"`        // ok; entire field is ignored in JSON
}

type UnexpectedSpacetest struct {
	A int `json:"a,omitempty"`
	B int `json:"b, omitempty"` // want "suspicious space in struct tag value"
	C int `json:"c ,omitempty"`
	D int `json:"d,omitempty, string"` // want "suspicious space in struct tag value"
	E int `xml:"e local"`
	F int `xml:"f "`                 // want "suspicious space in struct tag value"
	G int `xml:" g"`                 // want "suspicious space in struct tag value"
	H int `xml:"h ,omitempty"`       // want "suspicious space in struct tag value"
	I int `xml:"i, omitempty"`       // want "suspicious space in struct tag value"
	J int `xml:"j local ,omitempty"` // want "suspicious space in struct tag value"
	K int `xml:"k local, omitempty"` // want "suspicious space in struct tag value"
	L int `xml:" l local,omitempty"` // want "suspicious space in struct tag value"
	M int `xml:"m  local,omitempty"` // want "suspicious space in struct tag value"
	N int `xml:" "`                  // want "suspicious space in struct tag value"
	O int `xml:""`
	P int `xml:","`
	Q int `foo:" doesn't care "`
}

// Nested fields can be shadowed by fields further up. For example,
// ShadowingAnonJSON replaces the json:"a" field in AnonymousJSONField.
// However, if the two conflicting fields appear at the same level like in
// DuplicateWithAnotherPackage, we should error.

type ShadowingJsonFieldName struct {
	AnonymousJSONField
	ShadowingAnonJSON int `json:"a"`
}

type DuplicateWithAnotherPackage struct {
	b.AnonymousJSONField
	AnonymousJSONField2 // want "struct field DuplicateAnonJSON repeats json tag .a. also at b.b.go:8"
}


================================================
FILE: go/analysis/passes/structtag/testdata/src/a/b/b.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package b

type AnonymousJSONField struct {
	DuplicateAnonJSON int `json:"a"`
}


================================================
FILE: go/analysis/passes/testinggoroutine/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testinggoroutine defines an Analyzerfor detecting calls to
// Fatal from a test goroutine.
//
// # Analyzer testinggoroutine
//
// testinggoroutine: report calls to (*testing.T).Fatal from goroutines started by a test
//
// Functions that abruptly terminate a test, such as the Fatal, Fatalf, FailNow, and
// Skip{,f,Now} methods of *testing.T, must be called from the test goroutine itself.
// This checker detects calls to these functions that occur within a goroutine
// started by the test. For example:
//
//	func TestFoo(t *testing.T) {
//	    go func() {
//	        t.Fatal("oops") // error: (*T).Fatal called from non-test goroutine
//	    }()
//	}
package testinggoroutine


================================================
FILE: go/analysis/passes/testinggoroutine/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"log"
	"sync"
	"testing"
)

func TestBadFatalf(t *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < 2; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			t.Fatalf("TestFailed: id = %v\n", id) // want "call to .+T.+Fatalf from a non-test goroutine"
		}(i)
	}
}

func TestOKErrorf(t *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < 2; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			t.Errorf("TestFailed: id = %v\n", id)
		}(i)
	}
}

func TestBadFatal(t *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < 2; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			t.Fatal("TestFailed") // want "call to .+T.+Fatal from a non-test goroutine"
		}(i)
	}
}

func f(t *testing.T, _ string) {
	t.Fatal("TestFailed")
}

func g() {}

func TestBadFatalIssue47470(t *testing.T) {
	go f(t, "failed test 1") // want "call to .+T.+Fatal from a non-test goroutine"

	g := func(t *testing.T, _ string) {
		t.Fatal("TestFailed")
	}
	go g(t, "failed test 2") // want "call to .+T.+Fatal from a non-test goroutine"
}

func BenchmarkBadFatalf(b *testing.B) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < b.N; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			b.Fatalf("TestFailed: id = %v\n", id) // want "call to .+B.+Fatalf from a non-test goroutine"
		}(i)
	}
}

func BenchmarkBadFatal(b *testing.B) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < b.N; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			b.Fatal("TestFailed") // want "call to .+B.+Fatal from a non-test goroutine"
		}(i)
	}
}

func BenchmarkOKErrorf(b *testing.B) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < b.N; i++ {
		wg.Add(1)
		go func(id int) {
			defer wg.Done()
			b.Errorf("TestFailed: %d", i)
		}(i)
	}
}

func BenchmarkBadFatalGoGo(b *testing.B) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < b.N; i++ {
		wg.Add(1)
		go func(id int) {
			go func() {
				defer wg.Done()
				b.Fatal("TestFailed") // want "call to .+B.+Fatal from a non-test goroutine"
			}()
		}(i)
	}

	if false {
		defer b.Fatal("here")
	}

	if true {
		go func() {
			b.Fatal("in here") // want "call to .+B.+Fatal from a non-test goroutine"
		}()
	}

	func() {
		func() {
			func() {
				func() {
					go func() {
						b.Fatal("Here") // want "call to .+B.+Fatal from a non-test goroutine"
					}()
				}()
			}()
		}()
	}()

	_ = 10 * 10
	_ = func() bool {
		go b.Fatal("Failed") // want "call to .+B.+Fatal from a non-test goroutine"
		return true
	}

	defer func() {
		go b.Fatal("Here") // want "call to .+B.+Fatal from a non-test goroutine"
	}()
}

func BenchmarkBadSkip(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if i == 100 {
			go b.Skip("Skipping") // want "call to .+B.+Skip from a non-test goroutine"
		}
		if i == 22 {
			go func() {
				go func() {
					b.Skip("Skipping now") // want "call to .+B.+Skip from a non-test goroutine"
				}()
			}()
		}
	}
}

func TestBadSkip(t *testing.T) {
	for i := 0; i < 1000; i++ {
		if i == 100 {
			go t.Skip("Skipping") // want "call to .+T.+Skip from a non-test goroutine"
		}
		if i == 22 {
			go func() {
				go func() {
					t.Skip("Skipping now") // want "call to .+T.+Skip from a non-test goroutine"
				}()
			}()
		}
	}
}

func BenchmarkBadFailNow(b *testing.B) {
	for i := 0; i < b.N; i++ {
		if i == 100 {
			go b.FailNow() // want "call to .+B.+FailNow from a non-test goroutine"
		}
		if i == 22 {
			go func() {
				go func() {
					b.FailNow() // want "call to .+B.+FailNow from a non-test goroutine"
				}()
			}()
		}
	}
}

func TestBadFailNow(t *testing.T) {
	for i := 0; i < 1000; i++ {
		if i == 100 {
			go t.FailNow() // want "call to .+T.+FailNow from a non-test goroutine"
		}
		if i == 22 {
			go func() {
				go func() {
					t.FailNow() // want "call to .+T.+FailNow from a non-test goroutine"
				}()
			}()
		}
	}
}

func TestBadWithLoopCond(ty *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(id int) {
			defer ty.Fatalf("Why") // want "call to .+T.+Fatalf from a non-test goroutine"
			go func() {
				for j := 0; j < 2; ty.FailNow() { // want "call to .+T.+FailNow from"
					j++
					ty.Errorf("Done here")
				}
			}()
		}(i)
	}
}

type customType int

func (ct *customType) Fatalf(fmtSpec string, args ...interface{}) {
	if fmtSpec == "" {
		panic("empty format specifier")
	}
}

func (ct *customType) FailNow() {}
func (ct *customType) Skip()    {}

func TestWithLogFatalf(t *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(id int) {
			go func() {
				for j := 0; j < 2; j++ {
					log.Fatal("Done here")
				}
			}()
		}(i)
	}
}

func TestWithCustomType(t *testing.T) {
	var wg sync.WaitGroup
	defer wg.Wait()

	ct := new(customType)
	defer ct.FailNow()
	defer ct.Skip()

	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(id int) {
			go func() {
				for j := 0; j < 2; j++ {
					ct.Fatalf("Done here: %d", i)
				}
			}()
		}(i)
	}
}

func helpTB(tb testing.TB) {
	tb.FailNow()
}

func TestTB(t *testing.T) {
	go helpTB(t) // want "call to .+TB.+FailNow from a non-test goroutine"
}

func TestIssue48124(t *testing.T) {
	go helper(t) // want "call to .+T.+Skip from a non-test goroutine"
}

func TestEachCall(t *testing.T) {
	go helper(t) // want "call to .+T.+Skip from a non-test goroutine"
	go helper(t) // want "call to .+T.+Skip from a non-test goroutine"
}

func TestWithSubtest(t *testing.T) {
	t.Run("name", func(t2 *testing.T) {
		t.FailNow() // want "call to .+T.+FailNow on t defined outside of the subtest"
		t2.Fatal()
	})

	f := func(t3 *testing.T) {
		t.FailNow()
		t3.Fatal()
	}
	t.Run("name", f) // want "call to .+T.+FailNow on t defined outside of the subtest"

	g := func(t4 *testing.T) {
		t.FailNow()
		t4.Fatal()
	}
	g(t)

	t.Run("name", helper)

	go t.Run("name", func(t2 *testing.T) {
		t.FailNow() // want "call to .+T.+FailNow on t defined outside of the subtest"
		t2.Fatal()
	})
}

func TestMultipleVariables(t *testing.T) {
	{ // short decl
		f, g := func(t1 *testing.T) {
			t1.Fatal()
		}, func(t2 *testing.T) {
			t2.Error()
		}

		go f(t) // want "call to .+T.+Fatal from a non-test goroutine"
		go g(t)

		t.Run("name", f)
		t.Run("name", g)
	}

	{ // var decl
		var f, g = func(t1 *testing.T) {
			t1.Fatal()
		}, func(t2 *testing.T) {
			t2.Error()
		}

		go f(t) // want "call to .+T.+Fatal from a non-test goroutine"
		go g(t)

		t.Run("name", f)
		t.Run("name", g)
	}
}

func BadIgnoresMultipleAssignments(t *testing.T) {
	{
		f := func(t1 *testing.T) {
			t1.Fatal()
		}
		go f(t) // want "call to .+T.+Fatal from a non-test goroutine"

		f = func(t2 *testing.T) {
			t2.Error()
		}
		go f(t) // want "call to .+T.+Fatal from a non-test goroutine"
	}
	{
		f := func(t1 *testing.T) {
			t1.Error()
		}
		go f(t)

		f = func(t2 *testing.T) {
			t2.FailNow()
		}
		go f(t) // false negative
	}
}

func TestGoDoesNotDescendIntoSubtest(t *testing.T) {
	f := func(t2 *testing.T) {
		g := func(t3 *testing.T) {
			t3.Fatal() // fine
		}
		t2.Run("name", g)
		t2.FailNow() // bad
	}
	go f(t) // want "call to .+T.+FailNow from a non-test goroutine"
}

func TestFreeVariableAssignedWithinEnclosing(t *testing.T) {
	f := func(t2 *testing.T) {
		inner := t
		inner.FailNow()
	}

	go f(nil) // want "call to .+T.+FailNow from a non-test goroutine"

	t.Run("name", func(t3 *testing.T) {
		go f(nil) // want "call to .+T.+FailNow from a non-test goroutine"
	})

	// Without pointer analysis we cannot tell if inner is t or t2.
	// So we accept a false negatives on the following examples.
	t.Run("name", f)

	go func(_ *testing.T) {
		t.Run("name", f)
	}(nil)

	go t.Run("name", f)
}

func TestWithUnusedSelection(t *testing.T) {
	go func() {
		_ = t.FailNow
	}()
	t.Run("name", func(t2 *testing.T) {
		_ = t.FailNow
	})
}

func TestMethodExprsAreIgnored(t *testing.T) {
	go func() {
		(*testing.T).FailNow(t)
	}()
}

func TestRecursive(t *testing.T) {
	t.SkipNow()

	go TestRecursive(t) // want "call to .+T.+SkipNow from a non-test goroutine"

	t.Run("name", TestRecursive)
}

func TestMethodSelection(t *testing.T) {
	var h helperType

	go h.help(t) // want "call to .+T.+SkipNow from a non-test goroutine"
	t.Run("name", h.help)
}

type helperType struct{}

func (h *helperType) help(t *testing.T) { t.SkipNow() }

func TestIssue63799a(t *testing.T) {
	done := make(chan struct{})
	go func() {
		defer close(done)
		t.Run("", func(t *testing.T) {
			t.Fatal() // No warning. This is in a subtest.
		})
	}()
	<-done
}

func TestIssue63799b(t *testing.T) {
	// Simplified from go.dev/cl/538698

	// nondet is some unspecified boolean placeholder.
	var nondet func() bool

	t.Run("nohup", func(t *testing.T) {
		if nondet() {
			t.Skip("ignored")
		}

		go t.Run("nohup-i", func(t *testing.T) {
			t.Parallel()
			if nondet() {
				if nondet() {
					t.Skip("go.dev/cl/538698 wanted to have skip here")
				}

				t.Error("ignored")
			} else {
				t.Log("ignored")
			}
		})
	})
}

func TestIssue63849(t *testing.T) {
	go func() {
		helper(t) // False negative. We do not do an actual interprodecural reachability analysis.
	}()
	go helper(t) // want "call to .+T.+Skip from a non-test goroutine"
}


================================================
FILE: go/analysis/passes/testinggoroutine/testdata/src/a/b.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import "testing"

func helper(t *testing.T) {
	t.Skip()
}


================================================
FILE: go/analysis/passes/testinggoroutine/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"testing"
)

func f[P any](t *testing.T) {
	t.Fatal("failed")
}

func TestBadFatalf[P any](t *testing.T) {
	go f[int](t) // want "call to .+T.+Fatal from a non-test goroutine"
}


================================================
FILE: go/analysis/passes/testinggoroutine/testinggoroutine.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testinggoroutine

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var reportSubtest bool

func init() {
	Analyzer.Flags.BoolVar(&reportSubtest, "subtest", false, "whether to check if t.Run subtest is terminated correctly; experimental")
}

var Analyzer = &analysis.Analyzer{
	Name:     "testinggoroutine",
	Doc:      analyzerutil.MustExtractDoc(doc, "testinggoroutine"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/testinggoroutine",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	if !typesinternal.Imports(pass.Pkg, "testing") {
		return nil, nil
	}

	toDecl := localFunctionDecls(pass.TypesInfo, pass.Files)

	// asyncs maps nodes whose statements will be executed concurrently
	// with respect to some test function, to the call sites where they
	// are invoked asynchronously. There may be multiple such call sites
	// for e.g. test helpers.
	asyncs := make(map[ast.Node][]*asyncCall)
	var regions []ast.Node
	addCall := func(c *asyncCall) {
		if c != nil {
			r := c.region
			if asyncs[r] == nil {
				regions = append(regions, r)
			}
			asyncs[r] = append(asyncs[r], c)
		}
	}

	// Collect all of the go callee() and t.Run(name, callee) extents.
	inspect.Nodes([]ast.Node{
		(*ast.FuncDecl)(nil),
		(*ast.GoStmt)(nil),
		(*ast.CallExpr)(nil),
	}, func(node ast.Node, push bool) bool {
		if !push {
			return false
		}
		switch node := node.(type) {
		case *ast.FuncDecl:
			return hasBenchmarkOrTestParams(node)

		case *ast.GoStmt:
			c := goAsyncCall(pass.TypesInfo, node, toDecl)
			addCall(c)

		case *ast.CallExpr:
			c := tRunAsyncCall(pass.TypesInfo, node)
			addCall(c)
		}
		return true
	})

	// Check for t.Forbidden() calls within each region r that is a
	// callee in some go r() or a t.Run("name", r).
	//
	// Also considers a special case when r is a go t.Forbidden() call.
	for _, region := range regions {
		ast.Inspect(region, func(n ast.Node) bool {
			if n == region {
				return true // always descend into the region itself.
			} else if asyncs[n] != nil {
				return false // will be visited by another region.
			}

			call, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}
			x, sel, fn := forbiddenMethod(pass.TypesInfo, call)
			if x == nil {
				return true
			}

			for _, e := range asyncs[region] {
				if !withinScope(e.scope, x) {
					forbidden := formatMethod(sel, fn) // e.g. "(*testing.T).Forbidden

					var context string
					var where analysis.Range = e.async // Put the report at the go fun() or t.Run(name, fun).
					if _, local := e.fun.(*ast.FuncLit); local {
						where = call // Put the report at the t.Forbidden() call.
					} else if id, ok := e.fun.(*ast.Ident); ok {
						context = fmt.Sprintf(" (%s calls %s)", id.Name, forbidden)
					}
					if _, ok := e.async.(*ast.GoStmt); ok {
						pass.ReportRangef(where, "call to %s from a non-test goroutine%s", forbidden, context)
					} else if reportSubtest {
						pass.ReportRangef(where, "call to %s on %s defined outside of the subtest%s", forbidden, x.Name(), context)
					}
				}
			}
			return true
		})
	}

	return nil, nil
}

func hasBenchmarkOrTestParams(fnDecl *ast.FuncDecl) bool {
	// Check that the function's arguments include "*testing.T" or "*testing.B".
	params := fnDecl.Type.Params.List

	for _, param := range params {
		if _, ok := typeIsTestingDotTOrB(param.Type); ok {
			return true
		}
	}

	return false
}

func typeIsTestingDotTOrB(expr ast.Expr) (string, bool) {
	starExpr, ok := expr.(*ast.StarExpr)
	if !ok {
		return "", false
	}
	selExpr, ok := starExpr.X.(*ast.SelectorExpr)
	if !ok {
		return "", false
	}
	varPkg := selExpr.X.(*ast.Ident)
	if varPkg.Name != "testing" {
		return "", false
	}

	varTypeName := selExpr.Sel.Name
	ok = varTypeName == "B" || varTypeName == "T"
	return varTypeName, ok
}

// asyncCall describes a region of code that needs to be checked for
// t.Forbidden() calls as it is started asynchronously from an async
// node go fun() or t.Run(name, fun).
type asyncCall struct {
	region ast.Node // region of code to check for t.Forbidden() calls.
	async  ast.Node // *ast.GoStmt or *ast.CallExpr (for t.Run)
	scope  ast.Node // Report t.Forbidden() if t is not declared within scope.
	fun    ast.Expr // fun in go fun() or t.Run(name, fun)
}

// withinScope returns true if x.Pos() is in [scope.Pos(), scope.End()].
func withinScope(scope ast.Node, x *types.Var) bool {
	if scope != nil {
		return x.Pos() != token.NoPos && scope.Pos() <= x.Pos() && x.Pos() <= scope.End()
	}
	return false
}

// goAsyncCall returns the extent of a call from a go fun() statement.
func goAsyncCall(info *types.Info, goStmt *ast.GoStmt, toDecl func(*types.Func) *ast.FuncDecl) *asyncCall {
	call := goStmt.Call

	fun := ast.Unparen(call.Fun)
	if id := typesinternal.UsedIdent(info, fun); id != nil {
		if lit := funcLitInScope(id); lit != nil {
			return &asyncCall{region: lit, async: goStmt, scope: nil, fun: fun}
		}
	}

	if fn := typeutil.StaticCallee(info, call); fn != nil { // static call or method in the package?
		if decl := toDecl(fn); decl != nil {
			return &asyncCall{region: decl, async: goStmt, scope: nil, fun: fun}
		}
	}

	// Check go statement for go t.Forbidden() or go func(){t.Forbidden()}().
	return &asyncCall{region: goStmt, async: goStmt, scope: nil, fun: fun}
}

// tRunAsyncCall returns the extent of a call from a t.Run("name", fun) expression.
func tRunAsyncCall(info *types.Info, call *ast.CallExpr) *asyncCall {
	if len(call.Args) != 2 {
		return nil
	}
	run := typeutil.Callee(info, call)
	if run, ok := run.(*types.Func); !ok || !isMethodNamed(run, "testing", "Run") {
		return nil
	}

	fun := ast.Unparen(call.Args[1])
	if lit, ok := fun.(*ast.FuncLit); ok { // function lit?
		return &asyncCall{region: lit, async: call, scope: lit, fun: fun}
	}

	if id := typesinternal.UsedIdent(info, fun); id != nil {
		if lit := funcLitInScope(id); lit != nil { // function lit in variable?
			return &asyncCall{region: lit, async: call, scope: lit, fun: fun}
		}
	}

	// Check within t.Run(name, fun) for calls to t.Forbidden,
	// e.g. t.Run(name, func(t *testing.T){ t.Forbidden() })
	return &asyncCall{region: call, async: call, scope: fun, fun: fun}
}

var forbidden = []string{
	"FailNow",
	"Fatal",
	"Fatalf",
	"Skip",
	"Skipf",
	"SkipNow",
}

// forbiddenMethod decomposes a call x.m() into (x, x.m, m) where
// x is a variable, x.m is a selection, and m is the static callee m.
// Returns (nil, nil, nil) if call is not of this form.
func forbiddenMethod(info *types.Info, call *ast.CallExpr) (*types.Var, *types.Selection, *types.Func) {
	// Compare to typeutil.StaticCallee.
	fun := ast.Unparen(call.Fun)
	selExpr, ok := fun.(*ast.SelectorExpr)
	if !ok {
		return nil, nil, nil
	}
	sel := info.Selections[selExpr]
	if sel == nil {
		return nil, nil, nil
	}

	var x *types.Var
	if id, ok := ast.Unparen(selExpr.X).(*ast.Ident); ok {
		x, _ = info.Uses[id].(*types.Var)
	}
	if x == nil {
		return nil, nil, nil
	}

	fn, _ := sel.Obj().(*types.Func)
	if fn == nil || !isMethodNamed(fn, "testing", forbidden...) {
		return nil, nil, nil
	}
	return x, sel, fn
}

func formatMethod(sel *types.Selection, fn *types.Func) string {
	var ptr string
	rtype := sel.Recv()
	if p, ok := types.Unalias(rtype).(*types.Pointer); ok {
		ptr = "*"
		rtype = p.Elem()
	}
	return fmt.Sprintf("(%s%s).%s", ptr, rtype.String(), fn.Name())
}


================================================
FILE: go/analysis/passes/testinggoroutine/testinggoroutine_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testinggoroutine_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/testinggoroutine"
)

func init() {
	testinggoroutine.Analyzer.Flags.Set("subtest", "true")
}

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	pkgs := []string{"a", "typeparams"}
	analysistest.Run(t, testdata, testinggoroutine.Analyzer, pkgs...)
}


================================================
FILE: go/analysis/passes/testinggoroutine/util.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testinggoroutine

import (
	"go/ast"
	"go/types"
	"slices"
)

// AST and types utilities that not specific to testinggoroutines.

// localFunctionDecls returns a mapping from *types.Func to *ast.FuncDecl in files.
func localFunctionDecls(info *types.Info, files []*ast.File) func(*types.Func) *ast.FuncDecl {
	var fnDecls map[*types.Func]*ast.FuncDecl // computed lazily
	return func(f *types.Func) *ast.FuncDecl {
		if f != nil && fnDecls == nil {
			fnDecls = make(map[*types.Func]*ast.FuncDecl)
			for _, file := range files {
				for _, decl := range file.Decls {
					if fnDecl, ok := decl.(*ast.FuncDecl); ok {
						if fn, ok := info.Defs[fnDecl.Name].(*types.Func); ok {
							fnDecls[fn] = fnDecl
						}
					}
				}
			}
		}
		// TODO: set f = f.Origin() here.
		return fnDecls[f]
	}
}

// isMethodNamed returns true if f is a method defined
// in package with the path pkgPath with a name in names.
//
// (Unlike [analysis.IsMethodNamed], it ignores the receiver type name.)
func isMethodNamed(f *types.Func, pkgPath string, names ...string) bool {
	if f == nil {
		return false
	}
	if f.Pkg() == nil || f.Pkg().Path() != pkgPath {
		return false
	}
	if f.Signature().Recv() == nil {
		return false
	}
	return slices.Contains(names, f.Name())
}

// funcLitInScope returns a FuncLit that id is at least initially assigned to.
//
// TODO: This is closely tied to id.Obj which is deprecated.
func funcLitInScope(id *ast.Ident) *ast.FuncLit {
	// Compare to (*ast.Object).Pos().
	if id.Obj == nil {
		return nil
	}
	var rhs ast.Expr
	switch d := id.Obj.Decl.(type) {
	case *ast.AssignStmt:
		for i, x := range d.Lhs {
			if ident, isIdent := x.(*ast.Ident); isIdent && ident.Name == id.Name && i < len(d.Rhs) {
				rhs = d.Rhs[i]
			}
		}
	case *ast.ValueSpec:
		for i, n := range d.Names {
			if n.Name == id.Name && i < len(d.Values) {
				rhs = d.Values[i]
			}
		}
	}
	lit, _ := rhs.(*ast.FuncLit)
	return lit
}


================================================
FILE: go/analysis/passes/tests/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package tests defines an Analyzer that checks for common mistaken
// usages of tests and examples.
//
// # Analyzer tests
//
// tests: check for common mistaken usages of tests and examples
//
// The tests checker walks Test, Benchmark, Fuzzing and Example functions checking
// malformed names, wrong signatures and examples documenting non-existent
// identifiers.
//
// Please see the documentation for package testing in golang.org/pkg/testing
// for the conventions that are enforced for Tests, Benchmarks, and Examples.
package tests


================================================
FILE: go/analysis/passes/tests/testdata/src/a/a.go
================================================
package a

func Foo() {}


================================================
FILE: go/analysis/passes/tests/testdata/src/a/a_test.go
================================================
package a

import (
	"testing"
)

// Buf is a ...
type Buf []byte

// Append ...
func (*Buf) Append([]byte) {}

func (Buf) Reset() {}

func (Buf) Len() int { return 0 }

// DefaultBuf is a ...
var DefaultBuf Buf

func Example() {} // OK because is package-level.

func Example_goodSuffix() {} // OK because refers to suffix annotation.

func Example_BadSuffix() {} // want "Example_BadSuffix has malformed example suffix: BadSuffix"

func ExampleBuf() {} // OK because refers to known top-level type.

func ExampleBuf_Append() {} // OK because refers to known method.

func ExampleBuf_Clear() {} // want "ExampleBuf_Clear refers to unknown field or method: Buf.Clear"

func ExampleBuf_suffix() {} // OK because refers to suffix annotation.

func ExampleBuf_Append_Bad() {} // want "ExampleBuf_Append_Bad has malformed example suffix: Bad"

func ExampleBuf_Append_suffix() {} // OK because refers to known method with valid suffix.

func ExampleDefaultBuf() {} // OK because refers to top-level identifier.

func ExampleBuf_Reset() bool { return true } // want "ExampleBuf_Reset should return nothing"

func ExampleBuf_Len(i int) {} // want "ExampleBuf_Len should be niladic"

// "Puffer" is German for "Buffer".

func ExamplePuffer() {} // want "ExamplePuffer refers to unknown identifier: Puffer"

func ExamplePuffer_Append() {} // want "ExamplePuffer_Append refers to unknown identifier: Puffer"

func ExamplePuffer_suffix() {} // want "ExamplePuffer_suffix refers to unknown identifier: Puffer"

func ExampleFoo() {} // OK because a.Foo exists

func ExampleBar() {} // want "ExampleBar refers to unknown identifier: Bar"

func Example_withOutput() {
	// Output:
	// meow
} // OK because output is the last comment block

func Example_withBadOutput() {
	// Output: // want "output comment block must be the last comment block"
	// meow

	// todo: change to bark
}

func Example_withBadUnorderedOutput() {
	// Unordered Output: // want "output comment block must be the last comment block"
	// meow

	// todo: change to bark
}

func Example_withCommentAfterFunc() {
	// Output: // OK because it is the last comment block
	// meow
} // todo: change to bark

func Example_withOutputCommentAfterFunc() {
	// Output:
	// meow
} // Output: bark // OK because output is not inside of an example

func Example_withMultipleOutputs() {
	// Output: // want "there can only be one output comment block per example"
	// meow

	// Output: // want "there can only be one output comment block per example"
	// bark

	// Output: // OK because it is the last output comment block
	// ribbit
}

func nonTest() {} // OK because it doesn't start with "Test".

func (Buf) TesthasReceiver() {} // OK because it has a receiver.

func TestOKSuffix(*testing.T) {} // OK because first char after "Test" is Uppercase.

func TestÜnicodeWorks(*testing.T) {} // OK because the first char after "Test" is Uppercase.

func TestbadSuffix(*testing.T) {} // want "first letter after 'Test' must not be lowercase"

func TestemptyImportBadSuffix(*testing.T) {} // want "first letter after 'Test' must not be lowercase"

func Test(*testing.T) {} // OK "Test" on its own is considered a test.

func Testify() {} // OK because it takes no parameters.

func TesttooManyParams(*testing.T, string) {} // OK because it takes too many parameters.

func TesttooManyNames(a, b *testing.T) {} // OK because it takes too many names.

func TestnoTParam(string) {} // OK because it doesn't take a *testing.T

func BenchmarkbadSuffix(*testing.B) {} // want "first letter after 'Benchmark' must not be lowercase"


================================================
FILE: go/analysis/passes/tests/testdata/src/a/ax_test.go
================================================
package a_test

import _ "a"

func ExampleFoo() {} // OK because a.Foo exists

func ExampleBar() {} // want "ExampleBar refers to unknown identifier: Bar"


================================================
FILE: go/analysis/passes/tests/testdata/src/a/go118_test.go
================================================
package a

import (
	"testing"
)

func Fuzzfoo(*testing.F) {} // want "first letter after 'Fuzz' must not be lowercase"

func FuzzBoo(*testing.F) {} // OK because first letter after 'Fuzz' is Uppercase.

func FuzzCallDifferentFunc(f *testing.F) {
	f.Name() //OK
}

func FuzzFunc(f *testing.F) {
	f.Fuzz(func(t *testing.T) {}) // OK "first argument is of type *testing.T"
}

func FuzzFuncWithArgs(f *testing.F) {
	f.Add()                                      // want `wrong number of values in call to \(\*testing.F\)\.Add: 0, fuzz target expects 2`
	f.Add(1, 2, 3, 4)                            // want `wrong number of values in call to \(\*testing.F\)\.Add: 4, fuzz target expects 2`
	f.Add(5, 5)                                  // want `mismatched type in call to \(\*testing.F\)\.Add: int, fuzz target expects \[\]byte`
	f.Add([]byte("hello"), 5)                    // want `mismatched types in call to \(\*testing.F\)\.Add: \[\[\]byte int\], fuzz target expects \[int \[\]byte\]`
	f.Add(5, []byte("hello"))                    // OK
	f.Fuzz(func(t *testing.T, i int, b []byte) { // OK "arguments in func are allowed"
		f.Add(5, []byte("hello"))     // want `fuzz target must not call any \*F methods`
		f.Name()                      // OK "calls to (*F).Failed and (*F).Name are allowed"
		f.Failed()                    // OK "calls to (*F).Failed and (*F).Name are allowed"
		f.Fuzz(func(t *testing.T) {}) // want `fuzz target must not call any \*F methods`
	})
}

func FuzzArgFunc(f *testing.F) {
	f.Fuzz(0) // want "argument to Fuzz must be a function"
}

func FuzzFuncWithReturn(f *testing.F) {
	f.Fuzz(func(t *testing.T) bool { return true }) // want "fuzz target must not return any value"
}

func FuzzFuncNoArg(f *testing.F) {
	f.Fuzz(func() {}) // want "fuzz target must have 1 or more argument"
}

func FuzzFuncFirstArgNotTesting(f *testing.F) {
	f.Fuzz(func(i int64) {}) // want "the first parameter of a fuzz target must be \\*testing.T"
}

func FuzzFuncFirstArgTestingNotT(f *testing.F) {
	f.Fuzz(func(t *testing.F) {}) // want "the first parameter of a fuzz target must be \\*testing.T"
}

func FuzzFuncSecondArgNotAllowed(f *testing.F) {
	f.Fuzz(func(t *testing.T, i complex64) {}) // want "fuzzing arguments can only have the following types: string, bool, float32, float64, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, \\[\\]byte"
}

func FuzzFuncSecondArgArrNotAllowed(f *testing.F) {
	f.Fuzz(func(t *testing.T, i []int) {}) // want "fuzzing arguments can only have the following types: string, bool, float32, float64, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, \\[\\]byte"
}

func FuzzFuncConsecutiveArgNotAllowed(f *testing.F) {
	f.Fuzz(func(t *testing.T, i, j string, k complex64) {}) // want "fuzzing arguments can only have the following types: string, bool, float32, float64, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, \\[\\]byte"
}

func FuzzFuncInner(f *testing.F) {
	innerFunc := func(t *testing.T, i float32) {}
	f.Fuzz(innerFunc) // ok
}

func FuzzArrayOfFunc(f *testing.F) {
	var funcs = []func(t *testing.T, i int){func(t *testing.T, i int) {}}
	f.Fuzz(funcs[0]) // ok
}

type GenericSlice[T any] []T

func FuzzGenericFunc(f *testing.F) {
	g := GenericSlice[func(t *testing.T, i int)]{func(t *testing.T, i int) {}}
	f.Fuzz(g[0]) // ok
}

type F func(t *testing.T, i int32)

type myType struct {
	myVar F
}

func FuzzObjectMethod(f *testing.F) {
	obj := myType{
		myVar: func(t *testing.T, i int32) {},
	}
	f.Fuzz(obj.myVar) // ok
}

// Test for golang/go#56505: checking fuzz arguments should not panic on *error.
func FuzzIssue56505(f *testing.F) {
	f.Fuzz(func(e *error) {}) // want "the first parameter of a fuzz target must be \\*testing.T"
}


================================================
FILE: go/analysis/passes/tests/testdata/src/b/b.go
================================================
package b

type Foo struct {
}

func (f *Foo) F() {

}


================================================
FILE: go/analysis/passes/tests/testdata/src/b_x_test/b_test.go
================================================
package b_x_test

import (
	"a"
	"b"
)

func ExampleFoo_F() {
	var x b.Foo
	x.F()
	a.Foo()
}

func ExampleFoo_G() { // want "ExampleFoo_G refers to unknown field or method: Foo.G"

}

func ExampleBar_F() { // want "ExampleBar_F refers to unknown identifier: Bar"

}


================================================
FILE: go/analysis/passes/tests/testdata/src/divergent/buf.go
================================================
// Test of examples with divergent packages.

// Package buf ...
package buf

// Buf is a ...
type Buf []byte

// Append ...
func (*Buf) Append([]byte) {}

func (Buf) Reset() {}

func (Buf) Len() int { return 0 }

// DefaultBuf is a ...
var DefaultBuf Buf


================================================
FILE: go/analysis/passes/tests/testdata/src/divergent/buf_test.go
================================================
// Test of examples with divergent packages.

package buf

func Example() {} // OK because is package-level.

func Example_suffix() {} // OK because refers to suffix annotation.

func Example_BadSuffix() {} // want "Example_BadSuffix has malformed example suffix: BadSuffix"

func ExampleBuf() {} // OK because refers to known top-level type.

func ExampleBuf_Append() {} // OK because refers to known method.

func ExampleBuf_Clear() {} // want "ExampleBuf_Clear refers to unknown field or method: Buf.Clear"

func ExampleBuf_suffix() {} // OK because refers to suffix annotation.

func ExampleBuf_Append_Bad() {} // want "ExampleBuf_Append_Bad has malformed example suffix: Bad"

func ExampleBuf_Append_suffix() {} // OK because refers to known method with valid suffix.

func ExampleDefaultBuf() {} // OK because refers to top-level identifier.

func ExampleBuf_Reset() bool { return true } // want "ExampleBuf_Reset should return nothing"

func ExampleBuf_Len(i int) {} // want "ExampleBuf_Len should be niladic"

// "Puffer" is German for "Buffer".

func ExamplePuffer() {} // want "ExamplePuffer refers to unknown identifier: Puffer"

func ExamplePuffer_Append() {} // want "ExamplePuffer_Append refers to unknown identifier: Puffer"

func ExamplePuffer_suffix() {} // want "ExamplePuffer_suffix refers to unknown identifier: Puffer"


================================================
FILE: go/analysis/passes/tests/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

func Zero[T any]() T {
	var zero T
	return zero
}


================================================
FILE: go/analysis/passes/tests/testdata/src/typeparams/typeparams_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "testing"

func Test(*testing.T) {
	_ = Zero[int]() // It is fine to use generics within tests.
}

// Note: We format {Test,Benchmark}typeParam with a 't' in "type" to avoid an error from
// cmd/go/internal/load. That package can also give an error about Test and Benchmark
// functions with TypeParameters. These tests may need to be updated if that logic changes.
func TesttypeParam[T any](*testing.T)      {} // want "TesttypeParam has type parameters: it will not be run by go test as a TestXXX function" "TesttypeParam has malformed name"
func BenchmarktypeParam[T any](*testing.B) {} // want "BenchmarktypeParam has type parameters: it will not be run by go test as a BenchmarkXXX function" "BenchmarktypeParam has malformed name"

func ExampleZero[T any]() { // want "ExampleZero should not have type params"
	print(Zero[T]())
}


================================================
FILE: go/analysis/passes/tests/tests.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package tests

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"
	"regexp"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name: "tests",
	Doc:  analyzerutil.MustExtractDoc(doc, "tests"),
	URL:  "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/tests",
	Run:  run,
}

var acceptedFuzzTypes = []types.Type{
	types.Typ[types.String],
	types.Typ[types.Bool],
	types.Typ[types.Float32],
	types.Typ[types.Float64],
	types.Typ[types.Int],
	types.Typ[types.Int8],
	types.Typ[types.Int16],
	types.Typ[types.Int32],
	types.Typ[types.Int64],
	types.Typ[types.Uint],
	types.Typ[types.Uint8],
	types.Typ[types.Uint16],
	types.Typ[types.Uint32],
	types.Typ[types.Uint64],
	types.NewSlice(types.Universe.Lookup("byte").Type()),
}

func run(pass *analysis.Pass) (any, error) {
	for _, f := range pass.Files {
		if !strings.HasSuffix(pass.Fset.File(f.FileStart).Name(), "_test.go") {
			continue
		}
		for _, decl := range f.Decls {
			fn, ok := decl.(*ast.FuncDecl)
			if !ok || fn.Recv != nil {
				// Ignore non-functions or functions with receivers.
				continue
			}
			switch {
			case strings.HasPrefix(fn.Name.Name, "Example"):
				checkExampleName(pass, fn)
				checkExampleOutput(pass, fn, f.Comments)
			case strings.HasPrefix(fn.Name.Name, "Test"):
				checkTest(pass, fn, "Test")
			case strings.HasPrefix(fn.Name.Name, "Benchmark"):
				checkTest(pass, fn, "Benchmark")
			case strings.HasPrefix(fn.Name.Name, "Fuzz"):
				checkTest(pass, fn, "Fuzz")
				checkFuzz(pass, fn)
			}
		}
	}
	return nil, nil
}

// checkFuzz checks the contents of a fuzz function.
func checkFuzz(pass *analysis.Pass, fn *ast.FuncDecl) {
	params := checkFuzzCall(pass, fn)
	if params != nil {
		checkAddCalls(pass, fn, params)
	}
}

// checkFuzzCall checks the arguments of f.Fuzz() calls:
//
//  1. f.Fuzz() should call a function and it should be of type (*testing.F).Fuzz().
//  2. The called function in f.Fuzz(func(){}) should not return result.
//  3. First argument of func() should be of type *testing.T
//  4. Second argument onwards should be of type []byte, string, bool, byte,
//     rune, float32, float64, int, int8, int16, int32, int64, uint, uint8, uint16,
//     uint32, uint64
//  5. func() must not call any *F methods, e.g. (*F).Log, (*F).Error, (*F).Skip
//     The only *F methods that are allowed in the (*F).Fuzz function are (*F).Failed and (*F).Name.
//
// Returns the list of parameters to the fuzz function, if they are valid fuzz parameters.
func checkFuzzCall(pass *analysis.Pass, fn *ast.FuncDecl) (params *types.Tuple) {
	ast.Inspect(fn, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if ok {
			if !isFuzzTargetDotFuzz(pass, call) {
				return true
			}

			// Only one argument (func) must be passed to (*testing.F).Fuzz.
			if len(call.Args) != 1 {
				return true
			}
			expr := call.Args[0]
			if pass.TypesInfo.Types[expr].Type == nil {
				return true
			}
			t := pass.TypesInfo.Types[expr].Type.Underlying()
			tSign, argOk := t.(*types.Signature)
			// Argument should be a function
			if !argOk {
				pass.ReportRangef(expr, "argument to Fuzz must be a function")
				return false
			}
			// ff Argument function should not return
			if tSign.Results().Len() != 0 {
				pass.ReportRangef(expr, "fuzz target must not return any value")
			}
			// ff Argument function should have 1 or more argument
			if tSign.Params().Len() == 0 {
				pass.ReportRangef(expr, "fuzz target must have 1 or more argument")
				return false
			}
			ok := validateFuzzArgs(pass, tSign.Params(), expr)
			if ok && params == nil {
				params = tSign.Params()
			}
			// Inspect the function that was passed as an argument to make sure that
			// there are no calls to *F methods, except for Name and Failed.
			ast.Inspect(expr, func(n ast.Node) bool {
				if call, ok := n.(*ast.CallExpr); ok {
					if !isFuzzTargetDot(pass, call, "") {
						return true
					}
					if !isFuzzTargetDot(pass, call, "Name") && !isFuzzTargetDot(pass, call, "Failed") {
						pass.ReportRangef(call, "fuzz target must not call any *F methods")
					}
				}
				return true
			})
			// We do not need to look at any calls to f.Fuzz inside of a Fuzz call,
			// since they are not allowed.
			return false
		}
		return true
	})
	return params
}

// checkAddCalls checks that the arguments of f.Add calls have the same number and type of arguments as
// the signature of the function passed to (*testing.F).Fuzz
func checkAddCalls(pass *analysis.Pass, fn *ast.FuncDecl, params *types.Tuple) {
	ast.Inspect(fn, func(n ast.Node) bool {
		call, ok := n.(*ast.CallExpr)
		if ok {
			if !isFuzzTargetDotAdd(pass, call) {
				return true
			}

			// The first argument to function passed to (*testing.F).Fuzz is (*testing.T).
			if len(call.Args) != params.Len()-1 {
				pass.ReportRangef(call, "wrong number of values in call to (*testing.F).Add: %d, fuzz target expects %d", len(call.Args), params.Len()-1)
				return true
			}
			var mismatched []int
			for i, expr := range call.Args {
				if pass.TypesInfo.Types[expr].Type == nil {
					return true
				}
				t := pass.TypesInfo.Types[expr].Type
				if !types.Identical(t, params.At(i+1).Type()) {
					mismatched = append(mismatched, i)
				}
			}
			// If just one of the types is mismatched report for that
			// type only. Otherwise report for the whole call to (*testing.F).Add
			if len(mismatched) == 1 {
				i := mismatched[0]
				expr := call.Args[i]
				t := pass.TypesInfo.Types[expr].Type
				pass.ReportRangef(expr, "mismatched type in call to (*testing.F).Add: %v, fuzz target expects %v", t, params.At(i+1).Type())
			} else if len(mismatched) > 1 {
				var gotArgs, wantArgs []types.Type
				for i := 0; i < len(call.Args); i++ {
					gotArgs, wantArgs = append(gotArgs, pass.TypesInfo.Types[call.Args[i]].Type), append(wantArgs, params.At(i+1).Type())
				}
				pass.ReportRangef(call, "mismatched types in call to (*testing.F).Add: %v, fuzz target expects %v", gotArgs, wantArgs)
			}
		}
		return true
	})
}

// isFuzzTargetDotFuzz reports whether call is (*testing.F).Fuzz().
func isFuzzTargetDotFuzz(pass *analysis.Pass, call *ast.CallExpr) bool {
	return isFuzzTargetDot(pass, call, "Fuzz")
}

// isFuzzTargetDotAdd reports whether call is (*testing.F).Add().
func isFuzzTargetDotAdd(pass *analysis.Pass, call *ast.CallExpr) bool {
	return isFuzzTargetDot(pass, call, "Add")
}

// isFuzzTargetDot reports whether call is (*testing.F).<name>().
func isFuzzTargetDot(pass *analysis.Pass, call *ast.CallExpr, name string) bool {
	if selExpr, ok := call.Fun.(*ast.SelectorExpr); ok {
		if !isTestingType(pass.TypesInfo.Types[selExpr.X].Type, "F") {
			return false
		}
		if name == "" || selExpr.Sel.Name == name {
			return true
		}
	}
	return false
}

// Validate the arguments of fuzz target.
func validateFuzzArgs(pass *analysis.Pass, params *types.Tuple, expr ast.Expr) bool {
	fLit, isFuncLit := expr.(*ast.FuncLit)
	exprRange := expr
	ok := true
	if !isTestingType(params.At(0).Type(), "T") {
		if isFuncLit {
			exprRange = fLit.Type.Params.List[0].Type
		}
		pass.ReportRangef(exprRange, "the first parameter of a fuzz target must be *testing.T")
		ok = false
	}
	for i := 1; i < params.Len(); i++ {
		if !isAcceptedFuzzType(params.At(i).Type()) {
			if isFuncLit {
				curr := 0
				for _, field := range fLit.Type.Params.List {
					curr += len(field.Names)
					if i < curr {
						exprRange = field.Type
						break
					}
				}
			}
			pass.ReportRangef(exprRange, "fuzzing arguments can only have the following types: %s", formatAcceptedFuzzType())
			ok = false
		}
	}
	return ok
}

func isTestingType(typ types.Type, testingType string) bool {
	// No Unalias here: I doubt "go test" recognizes
	// "type A = *testing.T; func Test(A) {}" as a test.
	ptr, ok := typ.(*types.Pointer)
	if !ok {
		return false
	}
	return typesinternal.IsTypeNamed(ptr.Elem(), "testing", testingType)
}

// Validate that fuzz target function's arguments are of accepted types.
func isAcceptedFuzzType(paramType types.Type) bool {
	for _, typ := range acceptedFuzzTypes {
		if types.Identical(typ, paramType) {
			return true
		}
	}
	return false
}

func formatAcceptedFuzzType() string {
	var acceptedFuzzTypesStrings []string
	for _, typ := range acceptedFuzzTypes {
		acceptedFuzzTypesStrings = append(acceptedFuzzTypesStrings, typ.String())
	}
	acceptedFuzzTypesMsg := strings.Join(acceptedFuzzTypesStrings, ", ")
	return acceptedFuzzTypesMsg
}

func isExampleSuffix(s string) bool {
	r, size := utf8.DecodeRuneInString(s)
	return size > 0 && unicode.IsLower(r)
}

func isTestSuffix(name string) bool {
	if len(name) == 0 {
		// "Test" is ok.
		return true
	}
	r, _ := utf8.DecodeRuneInString(name)
	return !unicode.IsLower(r)
}

func isTestParam(typ ast.Expr, wantType string) bool {
	ptr, ok := typ.(*ast.StarExpr)
	if !ok {
		// Not a pointer.
		return false
	}
	// No easy way of making sure it's a *testing.T or *testing.B:
	// ensure the name of the type matches.
	if name, ok := ptr.X.(*ast.Ident); ok {
		return name.Name == wantType
	}
	if sel, ok := ptr.X.(*ast.SelectorExpr); ok {
		return sel.Sel.Name == wantType
	}
	return false
}

func lookup(pkg *types.Package, name string) []types.Object {
	if o := pkg.Scope().Lookup(name); o != nil {
		return []types.Object{o}
	}

	var ret []types.Object
	// Search through the imports to see if any of them define name.
	// It's hard to tell in general which package is being tested, so
	// for the purposes of the analysis, allow the object to appear
	// in any of the imports. This guarantees there are no false positives
	// because the example needs to use the object so it must be defined
	// in the package or one if its imports. On the other hand, false
	// negatives are possible, but should be rare.
	for _, imp := range pkg.Imports() {
		if obj := imp.Scope().Lookup(name); obj != nil {
			ret = append(ret, obj)
		}
	}
	return ret
}

// This pattern is taken from /go/src/go/doc/example.go
var outputRe = regexp.MustCompile(`(?i)^[[:space:]]*(unordered )?output:`)

type commentMetadata struct {
	isOutput bool
	pos      token.Pos
}

func checkExampleOutput(pass *analysis.Pass, fn *ast.FuncDecl, fileComments []*ast.CommentGroup) {
	commentsInExample := []commentMetadata{}
	numOutputs := 0

	// Find the comment blocks that are in the example. These comments are
	// guaranteed to be in order of appearance.
	for _, cg := range fileComments {
		if cg.Pos() < fn.Pos() {
			continue
		} else if cg.End() > fn.End() {
			break
		}

		isOutput := outputRe.MatchString(cg.Text())
		if isOutput {
			numOutputs++
		}

		commentsInExample = append(commentsInExample, commentMetadata{
			isOutput: isOutput,
			pos:      cg.Pos(),
		})
	}

	// Change message based on whether there are multiple output comment blocks.
	msg := "output comment block must be the last comment block"
	if numOutputs > 1 {
		msg = "there can only be one output comment block per example"
	}

	for i, cg := range commentsInExample {
		// Check for output comments that are not the last comment in the example.
		isLast := (i == len(commentsInExample)-1)
		if cg.isOutput && !isLast {
			pass.Report(
				analysis.Diagnostic{
					Pos:     cg.pos,
					Message: msg,
				},
			)
		}
	}
}

func checkExampleName(pass *analysis.Pass, fn *ast.FuncDecl) {
	fnName := fn.Name.Name
	if params := fn.Type.Params; len(params.List) != 0 {
		pass.Reportf(fn.Pos(), "%s should be niladic", fnName)
	}
	if results := fn.Type.Results; results != nil && len(results.List) != 0 {
		pass.Reportf(fn.Pos(), "%s should return nothing", fnName)
	}
	if tparams := fn.Type.TypeParams; tparams != nil && len(tparams.List) > 0 {
		pass.Reportf(fn.Pos(), "%s should not have type params", fnName)
	}

	if fnName == "Example" {
		// Nothing more to do.
		return
	}

	var (
		exName = strings.TrimPrefix(fnName, "Example")
		elems  = strings.SplitN(exName, "_", 3)
		ident  = elems[0]
		objs   = lookup(pass.Pkg, ident)
	)
	if ident != "" && len(objs) == 0 {
		// Check ExampleFoo and ExampleBadFoo.
		pass.Reportf(fn.Pos(), "%s refers to unknown identifier: %s", fnName, ident)
		// Abort since obj is absent and no subsequent checks can be performed.
		return
	}
	if len(elems) < 2 {
		// Nothing more to do.
		return
	}

	if ident == "" {
		// Check Example_suffix and Example_BadSuffix.
		if residual := strings.TrimPrefix(exName, "_"); !isExampleSuffix(residual) {
			pass.Reportf(fn.Pos(), "%s has malformed example suffix: %s", fnName, residual)
		}
		return
	}

	mmbr := elems[1]
	if !isExampleSuffix(mmbr) {
		// Check ExampleFoo_Method and ExampleFoo_BadMethod.
		found := false
		// Check if Foo.Method exists in this package or its imports.
		for _, obj := range objs {
			if obj, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), mmbr); obj != nil {
				found = true
				break
			}
		}
		if !found {
			pass.Reportf(fn.Pos(), "%s refers to unknown field or method: %s.%s", fnName, ident, mmbr)
		}
	}
	if len(elems) == 3 && !isExampleSuffix(elems[2]) {
		// Check ExampleFoo_Method_suffix and ExampleFoo_Method_Badsuffix.
		pass.Reportf(fn.Pos(), "%s has malformed example suffix: %s", fnName, elems[2])
	}
}

func checkTest(pass *analysis.Pass, fn *ast.FuncDecl, prefix string) {
	// Want functions with 0 results and 1 parameter.
	if fn.Type.Results != nil && len(fn.Type.Results.List) > 0 ||
		fn.Type.Params == nil ||
		len(fn.Type.Params.List) != 1 ||
		len(fn.Type.Params.List[0].Names) > 1 {
		return
	}

	// The param must look like a *testing.T or *testing.B.
	if !isTestParam(fn.Type.Params.List[0].Type, prefix[:1]) {
		return
	}

	if tparams := fn.Type.TypeParams; tparams != nil && len(tparams.List) > 0 {
		// Note: cmd/go/internal/load also errors about TestXXX and BenchmarkXXX functions with type parameters.
		// We have currently decided to also warn before compilation/package loading. This can help users in IDEs.
		pass.ReportRangef(astutil.RangeOf(tparams.Opening, tparams.Closing),
			"%s has type parameters: it will not be run by go test as a %sXXX function",
			fn.Name.Name, prefix)
	}

	if !isTestSuffix(fn.Name.Name[len(prefix):]) {
		pass.ReportRangef(fn.Name, "%s has malformed name: first letter after '%s' must not be lowercase", fn.Name.Name, prefix)
	}
}


================================================
FILE: go/analysis/passes/tests/tests_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package tests_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/tests"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, tests.Analyzer,
		"a",        // loads "a", "a [a.test]", and "a.test"
		"b_x_test", // loads "b" and "b_x_test"
		"divergent",
		"typeparams",
	)
}


================================================
FILE: go/analysis/passes/timeformat/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package timeformat defines an Analyzer that checks for the use
// of time.Format or time.Parse calls with a bad format.
//
// # Analyzer timeformat
//
// timeformat: check for calls of (time.Time).Format or time.Parse with 2006-02-01
//
// The timeformat checker looks for time formats with the 2006-02-01 (yyyy-dd-mm)
// format. Internationally, "yyyy-dd-mm" does not occur in common calendar date
// standards, and so it is more likely that 2006-01-02 (yyyy-mm-dd) was intended.
package timeformat


================================================
FILE: go/analysis/passes/timeformat/testdata/src/a/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the timeformat checker.

package a

import (
	"time"

	"b"
)

func hasError() {
	a, _ := time.Parse("2006-02-01 15:04:05", "2021-01-01 00:00:00") // want `2006-02-01 should be 2006-01-02`
	a.Format(`2006-02-01`)                                           // want `2006-02-01 should be 2006-01-02`
	a.Format("2006-02-01 15:04:05")                                  // want `2006-02-01 should be 2006-01-02`

	const c = "2006-02-01"
	a.Format(c) // want `2006-02-01 should be 2006-01-02`
}

func notHasError() {
	a, _ := time.Parse("2006-01-02 15:04:05", "2021-01-01 00:00:00")
	a.Format("2006-01-02")

	const c = "2006-01-02"
	a.Format(c)

	v := "2006-02-01"
	a.Format(v) // Allowed though variables.

	m := map[string]string{
		"y": "2006-02-01",
	}
	a.Format(m["y"])

	s := []string{"2006-02-01"}
	a.Format(s[0])

	a.Format(badFormat())

	o := b.Parse("2006-02-01 15:04:05", "2021-01-01 00:00:00")
	o.Format("2006-02-01")
}

func badFormat() string {
	return "2006-02-01"
}


================================================
FILE: go/analysis/passes/timeformat/testdata/src/a/a.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the timeformat checker.

package a

import (
	"time"

	"b"
)

func hasError() {
	a, _ := time.Parse("2006-01-02 15:04:05", "2021-01-01 00:00:00") // want `2006-02-01 should be 2006-01-02`
	a.Format(`2006-01-02`)                                           // want `2006-02-01 should be 2006-01-02`
	a.Format("2006-01-02 15:04:05")                                  // want `2006-02-01 should be 2006-01-02`

	const c = "2006-02-01"
	a.Format(c) // want `2006-02-01 should be 2006-01-02`
}

func notHasError() {
	a, _ := time.Parse("2006-01-02 15:04:05", "2021-01-01 00:00:00")
	a.Format("2006-01-02")

	const c = "2006-01-02"
	a.Format(c)

	v := "2006-02-01"
	a.Format(v) // Allowed though variables.

	m := map[string]string{
		"y": "2006-02-01",
	}
	a.Format(m["y"])

	s := []string{"2006-02-01"}
	a.Format(s[0])

	a.Format(badFormat())

	o := b.Parse("2006-02-01 15:04:05", "2021-01-01 00:00:00")
	o.Format("2006-02-01")
}

func badFormat() string {
	return "2006-02-01"
}


================================================
FILE: go/analysis/passes/timeformat/testdata/src/b/b.go
================================================
package b

type B struct {
}

func Parse(string, string) B {
	return B{}
}

func (b B) Format(string) {
}


================================================
FILE: go/analysis/passes/timeformat/timeformat.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package timeformat defines an Analyzer that checks for the use
// of time.Format or time.Parse calls with a bad format.
package timeformat

import (
	_ "embed"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

const badFormat = "2006-02-01"
const goodFormat = "2006-01-02"

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "timeformat",
	Doc:      analyzerutil.MustExtractDoc(doc, "timeformat"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/timeformat",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	// Note: (time.Time).Format is a method and can be a typeutil.Callee
	// without directly importing "time". So we cannot just skip this package
	// when !analysis.Imports(pass.Pkg, "time").
	// TODO(taking): Consider using a prepass to collect typeutil.Callees.

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		obj := typeutil.Callee(pass.TypesInfo, call)
		if !typesinternal.IsMethodNamed(obj, "time", "Time", "Format") &&
			!typesinternal.IsFunctionNamed(obj, "time", "Parse") {
			return
		}
		if len(call.Args) > 0 {
			arg := call.Args[0]
			badAt := badFormatAt(pass.TypesInfo, arg)

			if badAt > -1 {
				// Check if it's a literal string, otherwise we can't suggest a fix.
				if _, ok := arg.(*ast.BasicLit); ok {
					pos := int(arg.Pos()) + badAt + 1 // +1 to skip the " or `
					end := pos + len(badFormat)

					pass.Report(analysis.Diagnostic{
						Pos:     token.Pos(pos),
						End:     token.Pos(end),
						Message: badFormat + " should be " + goodFormat,
						SuggestedFixes: []analysis.SuggestedFix{{
							Message: "Replace " + badFormat + " with " + goodFormat,
							TextEdits: []analysis.TextEdit{{
								Pos:     token.Pos(pos),
								End:     token.Pos(end),
								NewText: []byte(goodFormat),
							}},
						}},
					})
				} else {
					pass.Reportf(arg.Pos(), badFormat+" should be "+goodFormat)
				}
			}
		}
	})
	return nil, nil
}

// badFormatAt return the start of a bad format in e or -1 if no bad format is found.
func badFormatAt(info *types.Info, e ast.Expr) int {
	tv, ok := info.Types[e]
	if !ok { // no type info, assume good
		return -1
	}

	t, ok := tv.Type.(*types.Basic) // sic, no unalias
	if !ok || t.Info()&types.IsString == 0 {
		return -1
	}

	if tv.Value == nil {
		return -1
	}

	return strings.Index(constant.StringVal(tv.Value), badFormat)
}


================================================
FILE: go/analysis/passes/timeformat/timeformat_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package timeformat_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/timeformat"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, timeformat.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/unmarshal/cmd/unmarshal/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The unmarshal command runs the unmarshal analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/passes/unmarshal"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(unmarshal.Analyzer) }


================================================
FILE: go/analysis/passes/unmarshal/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The unmarshal package defines an Analyzer that checks for passing
// non-pointer or non-interface types to unmarshal and decode functions.
//
// # Analyzer unmarshal
//
// unmarshal: report passing non-pointer or non-interface values to unmarshal
//
// The unmarshal analysis reports calls to functions such as json.Unmarshal
// in which the argument type is not a pointer or an interface.
package unmarshal


================================================
FILE: go/analysis/passes/unmarshal/testdata/src/a/a.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the unmarshal checker.

package testdata

import (
	"encoding/asn1"
	"encoding/gob"
	"encoding/json"
	"encoding/xml"
	"io"
)

func _() {
	type t struct {
		a int
	}
	var v t
	var r io.Reader

	json.Unmarshal([]byte{}, v) // want "call of Unmarshal passes non-pointer as second argument"
	json.Unmarshal([]byte{}, &v)
	json.NewDecoder(r).Decode(v) // want "call of Decode passes non-pointer"
	json.NewDecoder(r).Decode(&v)
	gob.NewDecoder(r).Decode(v) // want "call of Decode passes non-pointer"
	gob.NewDecoder(r).Decode(&v)
	xml.Unmarshal([]byte{}, v) // want "call of Unmarshal passes non-pointer as second argument"
	xml.Unmarshal([]byte{}, &v)
	xml.NewDecoder(r).Decode(v) // want "call of Decode passes non-pointer"
	xml.NewDecoder(r).Decode(&v)
	asn1.Unmarshal([]byte{}, v) // want "call of Unmarshal passes non-pointer as second argument"
	asn1.Unmarshal([]byte{}, &v)

	var p *t
	json.Unmarshal([]byte{}, p)
	json.Unmarshal([]byte{}, *p) // want "call of Unmarshal passes non-pointer as second argument"
	json.NewDecoder(r).Decode(p)
	json.NewDecoder(r).Decode(*p) // want "call of Decode passes non-pointer"
	gob.NewDecoder(r).Decode(p)
	gob.NewDecoder(r).Decode(*p) // want "call of Decode passes non-pointer"
	xml.Unmarshal([]byte{}, p)
	xml.Unmarshal([]byte{}, *p) // want "call of Unmarshal passes non-pointer as second argument"
	xml.NewDecoder(r).Decode(p)
	xml.NewDecoder(r).Decode(*p) // want "call of Decode passes non-pointer"
	asn1.Unmarshal([]byte{}, p)
	asn1.Unmarshal([]byte{}, *p) // want "call of Unmarshal passes non-pointer as second argument"

	var i interface{}
	json.Unmarshal([]byte{}, i)
	json.NewDecoder(r).Decode(i)

	json.Unmarshal([]byte{}, nil)               // want "call of Unmarshal passes non-pointer as second argument"
	json.Unmarshal([]byte{}, []t{})             // want "call of Unmarshal passes non-pointer as second argument"
	json.Unmarshal([]byte{}, map[string]int{})  // want "call of Unmarshal passes non-pointer as second argument"
	json.NewDecoder(r).Decode(nil)              // want "call of Decode passes non-pointer"
	json.NewDecoder(r).Decode([]t{})            // want "call of Decode passes non-pointer"
	json.NewDecoder(r).Decode(map[string]int{}) // want "call of Decode passes non-pointer"

	json.Unmarshal(func() ([]byte, interface{}) { return []byte{}, v }())
}


================================================
FILE: go/analysis/passes/unmarshal/testdata/src/typeparams/typeparams.go
================================================
package typeparams

import (
	"encoding/json"
	"fmt"
)

func unmarshalT[T any](data []byte) T {
	var x T
	json.Unmarshal(data, x)
	return x
}

func unmarshalT2[T any](data []byte, t T) {
    json.Unmarshal(data, t)
}

func main() {
	x := make(map[string]interface{})
	unmarshalT2([]byte(`{"a":1}`), &x)
	fmt.Println(x)
}

================================================
FILE: go/analysis/passes/unmarshal/unmarshal.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unmarshal

import (
	_ "embed"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "unmarshal",
	Doc:      analyzerutil.MustExtractDoc(doc, "unmarshal"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unmarshal",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	switch pass.Pkg.Path() {
	case "encoding/gob", "encoding/json", "encoding/xml", "encoding/asn1":
		// These packages know how to use their own APIs.
		// Sometimes they are testing what happens to incorrect programs.
		return nil, nil
	}

	// Note: (*"encoding/json".Decoder).Decode, (* "encoding/gob".Decoder).Decode
	// and (* "encoding/xml".Decoder).Decode are methods and can be a typeutil.Callee
	// without directly importing their packages. So we cannot just skip this package
	// when !analysis.Imports(pass.Pkg, "encoding/...").
	// TODO(taking): Consider using a prepass to collect typeutil.Callees.

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		fn := typeutil.StaticCallee(pass.TypesInfo, call)
		if fn == nil {
			return // not a static call
		}

		// Classify the callee (without allocating memory).
		argidx := -1

		recv := fn.Signature().Recv()
		if fn.Name() == "Unmarshal" && recv == nil {
			// "encoding/json".Unmarshal
			// "encoding/xml".Unmarshal
			// "encoding/asn1".Unmarshal
			switch fn.Pkg().Path() {
			case "encoding/json", "encoding/xml", "encoding/asn1":
				argidx = 1 // func([]byte, interface{})
			}
		} else if fn.Name() == "Decode" && recv != nil {
			// (*"encoding/json".Decoder).Decode
			// (* "encoding/gob".Decoder).Decode
			// (* "encoding/xml".Decoder).Decode
			_, named := typesinternal.ReceiverNamed(recv)
			if tname := named.Obj(); tname.Name() == "Decoder" {
				switch tname.Pkg().Path() {
				case "encoding/json", "encoding/xml", "encoding/gob":
					argidx = 0 // func(interface{})
				}
			}
		}
		if argidx < 0 {
			return // not a function we are interested in
		}

		if len(call.Args) < argidx+1 {
			return // not enough arguments, e.g. called with return values of another function
		}

		t := pass.TypesInfo.Types[call.Args[argidx]].Type
		switch t.Underlying().(type) {
		case *types.Pointer, *types.Interface, *types.TypeParam:
			return
		}

		switch argidx {
		case 0:
			pass.Reportf(call.Lparen, "call of %s passes non-pointer", fn.Name())
		case 1:
			pass.Reportf(call.Lparen, "call of %s passes non-pointer as second argument", fn.Name())
		}
	})
	return nil, nil
}


================================================
FILE: go/analysis/passes/unmarshal/unmarshal_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unmarshal_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/unmarshal"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, unmarshal.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/unreachable/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unreachable defines an Analyzer that checks for unreachable code.
//
// # Analyzer unreachable
//
// unreachable: check for unreachable code
//
// The unreachable analyzer finds statements that execution can never reach
// because they are preceded by a return statement, a call to panic, an
// infinite loop, or similar constructs.
package unreachable


================================================
FILE: go/analysis/passes/unreachable/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unreachable

// This file produces masses of errors from the type checker due to
// missing returns statements and other things.

type T int

var x interface{}
var c chan int

func external() int // ok

func _() int {
}

func _() int {
	print(1)
}

func _() int {
	print(1)
	return 2
	println() // want "unreachable code"
}

func _() int {
L:
	print(1)
	goto L
	println() // want "unreachable code"
}

func _() int {
	print(1)
	panic(2)
	println() // want "unreachable code"
}

// but only builtin panic
func _() int {
	var panic = func(int) {}
	print(1)
	panic(2)
	println() // ok
}

func _() int {
	{
		print(1)
		return 2
		println() // want "unreachable code"
	}
	println() // ok
}

func _() int {
	{
		print(1)
		return 2
	}
	println() // want "unreachable code"
}

func _() int {
L:
	{
		print(1)
		goto L
		println() // want "unreachable code"
	}
	println() // ok
}

func _() int {
L:
	{
		print(1)
		goto L
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	print(1)
	{
		panic(2)
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	return 2
	{ // want "unreachable code"
	}
}

func _() int {
L:
	print(1)
	goto L
	{ // want "unreachable code"
	}
}

func _() int {
	print(1)
	panic(2)
	{ // want "unreachable code"
	}
}

func _() int {
	{
		print(1)
		return 2
		{ // want "unreachable code"
		}
	}
}

func _() int {
L:
	{
		print(1)
		goto L
		{ // want "unreachable code"
		}
	}
}

func _() int {
	print(1)
	{
		panic(2)
		{ // want "unreachable code"
		}
	}
}

func _() int {
	{
		print(1)
		return 2
	}
	{ // want "unreachable code"
	}
}

func _() int {
L:
	{
		print(1)
		goto L
	}
	{ // want "unreachable code"
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
	{ // want "unreachable code"
	}
}

func _() int {
	print(1)
	if x == nil {
		panic(2)
	} else {
		panic(3)
	}
	println() // want "unreachable code"
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else {
		goto L
	}
	println() // want "unreachable code"
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 2 {
		panic(3)
	} else {
		goto L
	}
	println() // want "unreachable code"
}

// if-else chain missing final else is not okay, even if the
// conditions cover every possible case.

func _() int {
	print(1)
	if x == nil {
		panic(2)
	} else if x != nil {
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	if x == nil {
		panic(2)
	}
	println() // ok
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 1 {
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	for {
	}
	println() // want "unreachable code"
}

func _() int {
	for {
		for {
			break
		}
	}
	println() // want "unreachable code"
}

func _() int {
	for {
		for {
			break
			println() // want "unreachable code"
		}
	}
}

func _() int {
	for {
		for {
			continue
			println() // want "unreachable code"
		}
	}
}

func _() int {
	for {
	L:
		for {
			break L
		}
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	for {
		break
	}
	println() // ok
}

func _() int {
	for {
		for {
		}
		break // want "unreachable code"
	}
	println() // ok
}

func _() int {
L:
	for {
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	for x == nil {
	}
	println() // ok
}

func _() int {
	for x == nil {
		for {
			break
		}
	}
	println() // ok
}

func _() int {
	for x == nil {
	L:
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	for true {
	}
	println() // ok
}

func _() int {
	for true {
		for {
			break
		}
	}
	println() // ok
}

func _() int {
	for true {
	L:
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	select {}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
	println() // want "unreachable code"
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	case c <- 1:
		print(2)
		goto L
		println() // want "unreachable code"
	}
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	default:
		select {}
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
	}
	println() // ok
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		goto L // want "unreachable code"
	case c <- 1:
		print(2)
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		print(2)
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	default:
		break
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		break // want "unreachable code"
	}
	println() // ok
}

func _() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		break L
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(1)
		panic("abc")
	default:
		select {}
		break // want "unreachable code"
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
		println() // want "unreachable code"
	default:
		return 4
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
		println() // want "unreachable code"
	case 1:
		print(2)
		panic(3)
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch {
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	case 2:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 2:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	case 2:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		panic(3)
		break L // want "unreachable code"
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
		break // want "unreachable code"
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
		println() // want "unreachable code"
	default:
		return 4
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
		println() // want "unreachable code"
	case int:
		print(2)
		panic(3)
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
		println() // want "unreachable code"
	}
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
	println() // want "unreachable code"
}

func _() int {
	print(1)
	switch {
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	case float64:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case float64:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	case float64:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		panic(3)
		break L // want "unreachable code"
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
		break // want "unreachable code"
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

// again, but without the leading print(1).
// testing that everything works when the terminating statement is first.

func _() int {
	println() // ok
}

func _() int {
	return 2
	println() // want "unreachable code"
}

func _() int {
L:
	goto L
	println() // want "unreachable code"
}

func _() int {
	panic(2)
	println() // want "unreachable code"
}

// but only builtin panic
func _() int {
	var panic = func(int) {}
	panic(2)
	println() // ok
}

func _() int {
	{
		return 2
		println() // want "unreachable code"
	}
}

func _() int {
	{
		return 2
	}
	println() // want "unreachable code"
}

func _() int {
L:
	{
		goto L
		println() // want "unreachable code"
	}
}

func _() int {
L:
	{
		goto L
	}
	println() // want "unreachable code"
}

func _() int {
	{
		panic(2)
		println() // want "unreachable code"
	}
}

func _() int {
	{
		panic(2)
	}
	println() // want "unreachable code"
}

func _() int {
	return 2
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
L:
	goto L
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
	panic(2)
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
	{
		return 2
		{ // want "unreachable code"
		}
	}
	println() // ok
}

func _() int {
L:
	{
		goto L
		{ // want "unreachable code"
		}
	}
	println() // ok
}

func _() int {
	{
		panic(2)
		{ // want "unreachable code"
		}
	}
	println() // ok
}

func _() int {
	{
		return 2
	}
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
L:
	{
		goto L
	}
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
	{
		panic(2)
	}
	{ // want "unreachable code"
	}
	println() // ok
}

// again, with func literals

var _ = func() int {
}

var _ = func() int {
	print(1)
}

var _ = func() int {
	print(1)
	return 2
	println() // want "unreachable code"
}

var _ = func() int {
L:
	print(1)
	goto L
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	panic(2)
	println() // want "unreachable code"
}

// but only builtin panic
var _ = func() int {
	var panic = func(int) {}
	print(1)
	panic(2)
	println() // ok
}

var _ = func() int {
	{
		print(1)
		return 2
		println() // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	{
		print(1)
		return 2
	}
	println() // want "unreachable code"
}

var _ = func() int {
L:
	{
		print(1)
		goto L
		println() // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	return 2
	{ // want "unreachable code"
	}
}

var _ = func() int {
L:
	print(1)
	goto L
	{ // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	panic(2)
	{ // want "unreachable code"
	}
}

var _ = func() int {
	{
		print(1)
		return 2
		{ // want "unreachable code"
		}
	}
}

var _ = func() int {
L:
	{
		print(1)
		goto L
		{ // want "unreachable code"
		}
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
		{ // want "unreachable code"
		}
	}
}

var _ = func() int {
	{
		print(1)
		return 2
	}
	{ // want "unreachable code"
	}
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
	{ // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
	{ // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	} else {
		panic(3)
	}
	println() // want "unreachable code"
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else {
		goto L
	}
	println() // want "unreachable code"
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 2 {
		panic(3)
	} else {
		goto L
	}
	println() // want "unreachable code"
}

// if-else chain missing final else is not okay, even if the
// conditions cover every possible case.

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	} else if x != nil {
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	}
	println() // ok
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 1 {
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for {
	}
	println() // want "unreachable code"
}

var _ = func() int {
	for {
		for {
			break
		}
	}
	println() // want "unreachable code"
}

var _ = func() int {
	for {
		for {
			break
			println() // want "unreachable code"
		}
	}
}

var _ = func() int {
	for {
		for {
			continue
			println() // want "unreachable code"
		}
	}
}

var _ = func() int {
	for {
	L:
		for {
			break L
		}
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	for {
		break
	}
	println() // ok
}

var _ = func() int {
	for {
		for {
		}
		break // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
L:
	for {
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for x == nil {
	}
	println() // ok
}

var _ = func() int {
	for x == nil {
		for {
			break
		}
	}
	println() // ok
}

var _ = func() int {
	for x == nil {
	L:
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for true {
	}
	println() // ok
}

var _ = func() int {
	for true {
		for {
			break
		}
	}
	println() // ok
}

var _ = func() int {
	for true {
	L:
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
	println() // want "unreachable code"
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	case c <- 1:
		print(2)
		goto L
		println() // want "unreachable code"
	}
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		println() // want "unreachable code"
	default:
		select {}
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
	}
	println() // ok
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		goto L // want "unreachable code"
	case c <- 1:
		print(2)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		print(2)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	default:
		break
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
		break // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		break L
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(1)
		panic("abc")
	default:
		select {}
		break // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
		println() // want "unreachable code"
	default:
		return 4
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
		println() // want "unreachable code"
	case 1:
		print(2)
		panic(3)
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch {
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	case 2:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 2:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	case 2:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		panic(3)
		break L // want "unreachable code"
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
		break // want "unreachable code"
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
		println() // want "unreachable code"
	default:
		return 4
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
		println() // want "unreachable code"
	case int:
		print(2)
		panic(3)
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
		println() // want "unreachable code"
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
	println() // want "unreachable code"
}

var _ = func() int {
	print(1)
	switch {
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	case float64:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case float64:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	case float64:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		panic(3)
		break L // want "unreachable code"
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
		break // want "unreachable code"
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

// again, but without the leading print(1).
// testing that everything works when the terminating statement is first.

var _ = func() int {
	println() // ok
}

var _ = func() int {
	return 2
	println() // want "unreachable code"
}

var _ = func() int {
L:
	goto L
	println() // want "unreachable code"
}

var _ = func() int {
	panic(2)
	println() // want "unreachable code"
}

// but only builtin panic
var _ = func() int {
	var panic = func(int) {}
	panic(2)
	println() // ok
}

var _ = func() int {
	{
		return 2
		println() // want "unreachable code"
	}
}

var _ = func() int {
	{
		return 2
	}
	println() // want "unreachable code"
}

var _ = func() int {
L:
	{
		goto L
		println() // want "unreachable code"
	}
}

var _ = func() int {
L:
	{
		goto L
	}
	println() // want "unreachable code"
}

var _ = func() int {
	{
		panic(2)
		println() // want "unreachable code"
	}
}

var _ = func() int {
	{
		panic(2)
	}
	println() // want "unreachable code"
}

var _ = func() int {
	return 2
	{ // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
L:
	goto L
	{ // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	panic(2)
	{ // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	{
		return 2
		{ // want "unreachable code"
		}
	}
	println() // ok
}

var _ = func() int {
L:
	{
		goto L
		{ // want "unreachable code"
		}
	}
	println() // ok
}

var _ = func() int {
	{
		panic(2)
		{ // want "unreachable code"
		}
	}
	println() // ok
}

var _ = func() int {
	{
		return 2
	}
	{ // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
L:
	{
		goto L
	}
	{ // want "unreachable code"
	}
	println() // ok
}

var _ = func() int {
	{
		panic(2)
	}
	{ // want "unreachable code"
	}
	println() // ok
}

func _() int {
	// Empty switch tag with non-bool case value used to panic.
	switch {
	case 1:
		println()
	}
	println()
}


================================================
FILE: go/analysis/passes/unreachable/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unreachable

// This file produces masses of errors from the type checker due to
// missing returns statements and other things.

type T int

var x interface{}
var c chan int

func external() int // ok

func _() int {
}

func _() int {
	print(1)
}

func _() int {
	print(1)
	return 2
}

func _() int {
L:
	print(1)
	goto L
}

func _() int {
	print(1)
	panic(2)
}

// but only builtin panic
func _() int {
	var panic = func(int) {}
	print(1)
	panic(2)
	println() // ok
}

func _() int {
	{
		print(1)
		return 2
	}
	println() // ok
}

func _() int {
	{
		print(1)
		return 2
	}
}

func _() int {
L:
	{
		print(1)
		goto L
	}
	println() // ok
}

func _() int {
L:
	{
		print(1)
		goto L
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	print(1)
	return 2
}

func _() int {
L:
	print(1)
	goto L
}

func _() int {
	print(1)
	panic(2)
}

func _() int {
	{
		print(1)
		return 2
	}
}

func _() int {
L:
	{
		print(1)
		goto L
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	{
		print(1)
		return 2
	}
}

func _() int {
L:
	{
		print(1)
		goto L
	}
}

func _() int {
	print(1)
	{
		panic(2)
	}
}

func _() int {
	print(1)
	if x == nil {
		panic(2)
	} else {
		panic(3)
	}
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else {
		goto L
	}
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 2 {
		panic(3)
	} else {
		goto L
	}
}

// if-else chain missing final else is not okay, even if the
// conditions cover every possible case.

func _() int {
	print(1)
	if x == nil {
		panic(2)
	} else if x != nil {
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	if x == nil {
		panic(2)
	}
	println() // ok
}

func _() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 1 {
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	for {
	}
}

func _() int {
	for {
		for {
			break
		}
	}
}

func _() int {
	for {
		for {
			break
		}
	}
}

func _() int {
	for {
		for {
			continue
		}
	}
}

func _() int {
	for {
	L:
		for {
			break L
		}
	}
}

func _() int {
	print(1)
	for {
		break
	}
	println() // ok
}

func _() int {
	for {
		for {
		}
	}
	println() // ok
}

func _() int {
L:
	for {
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	for x == nil {
	}
	println() // ok
}

func _() int {
	for x == nil {
		for {
			break
		}
	}
	println() // ok
}

func _() int {
	for x == nil {
	L:
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	for true {
	}
	println() // ok
}

func _() int {
	for true {
		for {
			break
		}
	}
	println() // ok
}

func _() int {
	for true {
	L:
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
	select {}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
	}
	println() // ok
}

func _() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		print(2)
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	default:
		break
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
	println() // ok
}

func _() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		for {
			break L
		}
	}
	println() // ok
}

func _() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		break L
	}
	println() // ok
}

func _() int {
	print(1)
	select {
	case <-c:
		print(1)
		panic("abc")
	default:
		select {}
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch {
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	case 2:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 2:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	case 2:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
}

func _() int {
	print(1)
	switch {
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	case float64:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case float64:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	case float64:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // ok
}

func _() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

func _() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

// again, but without the leading print(1).
// testing that everything works when the terminating statement is first.

func _() int {
	println() // ok
}

func _() int {
	return 2
}

func _() int {
L:
	goto L
}

func _() int {
	panic(2)
}

// but only builtin panic
func _() int {
	var panic = func(int) {}
	panic(2)
	println() // ok
}

func _() int {
	{
		return 2
	}
}

func _() int {
	{
		return 2
	}
}

func _() int {
L:
	{
		goto L
	}
}

func _() int {
L:
	{
		goto L
	}
}

func _() int {
	{
		panic(2)
	}
}

func _() int {
	{
		panic(2)
	}
}

func _() int {
	return 2
	println() // ok
}

func _() int {
L:
	goto L
	println() // ok
}

func _() int {
	panic(2)
	println() // ok
}

func _() int {
	{
		return 2
	}
	println() // ok
}

func _() int {
L:
	{
		goto L
	}
	println() // ok
}

func _() int {
	{
		panic(2)
	}
	println() // ok
}

func _() int {
	{
		return 2
	}
	println() // ok
}

func _() int {
L:
	{
		goto L
	}
	println() // ok
}

func _() int {
	{
		panic(2)
	}
	println() // ok
}

// again, with func literals

var _ = func() int {
}

var _ = func() int {
	print(1)
}

var _ = func() int {
	print(1)
	return 2
}

var _ = func() int {
L:
	print(1)
	goto L
}

var _ = func() int {
	print(1)
	panic(2)
}

// but only builtin panic
var _ = func() int {
	var panic = func(int) {}
	print(1)
	panic(2)
	println() // ok
}

var _ = func() int {
	{
		print(1)
		return 2
	}
	println() // ok
}

var _ = func() int {
	{
		print(1)
		return 2
	}
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
	println() // ok
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	print(1)
	return 2
}

var _ = func() int {
L:
	print(1)
	goto L
}

var _ = func() int {
	print(1)
	panic(2)
}

var _ = func() int {
	{
		print(1)
		return 2
	}
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	{
		print(1)
		return 2
	}
}

var _ = func() int {
L:
	{
		print(1)
		goto L
	}
}

var _ = func() int {
	print(1)
	{
		panic(2)
	}
}

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	} else {
		panic(3)
	}
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else {
		goto L
	}
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 2 {
		panic(3)
	} else {
		goto L
	}
}

// if-else chain missing final else is not okay, even if the
// conditions cover every possible case.

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	} else if x != nil {
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	if x == nil {
		panic(2)
	}
	println() // ok
}

var _ = func() int {
L:
	print(1)
	if x == nil {
		panic(2)
	} else if x == 1 {
		return 0
	} else if x != 1 {
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for {
	}
}

var _ = func() int {
	for {
		for {
			break
		}
	}
}

var _ = func() int {
	for {
		for {
			break
		}
	}
}

var _ = func() int {
	for {
		for {
			continue
		}
	}
}

var _ = func() int {
	for {
	L:
		for {
			break L
		}
	}
}

var _ = func() int {
	print(1)
	for {
		break
	}
	println() // ok
}

var _ = func() int {
	for {
		for {
		}
	}
	println() // ok
}

var _ = func() int {
L:
	for {
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for x == nil {
	}
	println() // ok
}

var _ = func() int {
	for x == nil {
		for {
			break
		}
	}
	println() // ok
}

var _ = func() int {
	for x == nil {
	L:
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	for true {
	}
	println() // ok
}

var _ = func() int {
	for true {
		for {
			break
		}
	}
	println() // ok
}

var _ = func() int {
	for true {
	L:
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		for {
		}
	}
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		goto L
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		select {}
	}
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
	}
	println() // ok
}

var _ = func() int {
L:
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	default:
		print(2)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	default:
		break
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(2)
		panic("abc")
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		for {
			break L
		}
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	select {
	case <-c:
		print(2)
		panic("abc")
	case c <- 1:
		print(2)
		break L
	}
	println() // ok
}

var _ = func() int {
	print(1)
	select {
	case <-c:
		print(1)
		panic("abc")
	default:
		select {}
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch {
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	case 2:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 2:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		fallthrough
	case 2:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x {
	default:
		return 4
	case 1:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x {
	case 1:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	default:
		return 4
	}
}

var _ = func() int {
	print(1)
	switch {
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	case float64:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case float64:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		fallthrough
	case float64:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		panic(3)
	default:
		return 4
	}
	println() // ok
}

var _ = func() int {
	print(1)
	switch x.(type) {
	default:
		return 4
	case int:
		print(2)
		panic(3)
	}
	println() // ok
}

var _ = func() int {
	print(1)
L:
	switch x.(type) {
	case int:
		print(2)
		for {
			break L
		}
	default:
		return 4
	}
	println() // ok
}

// again, but without the leading print(1).
// testing that everything works when the terminating statement is first.

var _ = func() int {
	println() // ok
}

var _ = func() int {
	return 2
}

var _ = func() int {
L:
	goto L
}

var _ = func() int {
	panic(2)
}

// but only builtin panic
var _ = func() int {
	var panic = func(int) {}
	panic(2)
	println() // ok
}

var _ = func() int {
	{
		return 2
	}
}

var _ = func() int {
	{
		return 2
	}
}

var _ = func() int {
L:
	{
		goto L
	}
}

var _ = func() int {
L:
	{
		goto L
	}
}

var _ = func() int {
	{
		panic(2)
	}
}

var _ = func() int {
	{
		panic(2)
	}
}

var _ = func() int {
	return 2
	println() // ok
}

var _ = func() int {
L:
	goto L
	println() // ok
}

var _ = func() int {
	panic(2)
	println() // ok
}

var _ = func() int {
	{
		return 2
	}
	println() // ok
}

var _ = func() int {
L:
	{
		goto L
	}
	println() // ok
}

var _ = func() int {
	{
		panic(2)
	}
	println() // ok
}

var _ = func() int {
	{
		return 2
	}
	println() // ok
}

var _ = func() int {
L:
	{
		goto L
	}
	println() // ok
}

var _ = func() int {
	{
		panic(2)
	}
	println() // ok
}

func _() int {
	// Empty switch tag with non-bool case value used to panic.
	switch {
	case 1:
		println()
	}
	println()
}


================================================
FILE: go/analysis/passes/unreachable/unreachable.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unreachable

// TODO(adonovan): use the new cfg package, which is more precise.

import (
	_ "embed"
	"go/ast"
	"go/token"
	"log"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/refactor"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "unreachable",
	Doc:              analyzerutil.MustExtractDoc(doc, "unreachable"),
	URL:              "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unreachable",
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	RunDespiteErrors: true,
	Run:              run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.FuncDecl)(nil),
		(*ast.FuncLit)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		var body *ast.BlockStmt
		switch n := n.(type) {
		case *ast.FuncDecl:
			body = n.Body
		case *ast.FuncLit:
			body = n.Body
		}
		if body == nil {
			return
		}
		d := &deadState{
			pass:     pass,
			hasBreak: make(map[ast.Stmt]bool),
			hasGoto:  make(map[string]bool),
			labels:   make(map[string]ast.Stmt),
		}
		d.findLabels(body)
		d.reachable = true
		d.findDead(body)
	})
	return nil, nil
}

type deadState struct {
	pass        *analysis.Pass
	hasBreak    map[ast.Stmt]bool
	hasGoto     map[string]bool
	labels      map[string]ast.Stmt
	breakTarget ast.Stmt

	reachable bool
}

// findLabels gathers information about the labels defined and used by stmt
// and about which statements break, whether a label is involved or not.
func (d *deadState) findLabels(stmt ast.Stmt) {
	switch x := stmt.(type) {
	default:
		log.Fatalf("%s: internal error in findLabels: unexpected statement %T", d.pass.Fset.Position(x.Pos()), x)

	case *ast.AssignStmt,
		*ast.BadStmt,
		*ast.DeclStmt,
		*ast.DeferStmt,
		*ast.EmptyStmt,
		*ast.ExprStmt,
		*ast.GoStmt,
		*ast.IncDecStmt,
		*ast.ReturnStmt,
		*ast.SendStmt:
		// no statements inside

	case *ast.BlockStmt:
		for _, stmt := range x.List {
			d.findLabels(stmt)
		}

	case *ast.BranchStmt:
		switch x.Tok {
		case token.GOTO:
			if x.Label != nil {
				d.hasGoto[x.Label.Name] = true
			}

		case token.BREAK:
			stmt := d.breakTarget
			if x.Label != nil {
				stmt = d.labels[x.Label.Name]
			}
			if stmt != nil {
				d.hasBreak[stmt] = true
			}
		}

	case *ast.IfStmt:
		d.findLabels(x.Body)
		if x.Else != nil {
			d.findLabels(x.Else)
		}

	case *ast.LabeledStmt:
		d.labels[x.Label.Name] = x.Stmt
		d.findLabels(x.Stmt)

	// These cases are all the same, but the x.Body only works
	// when the specific type of x is known, so the cases cannot
	// be merged.
	case *ast.ForStmt:
		outer := d.breakTarget
		d.breakTarget = x
		d.findLabels(x.Body)
		d.breakTarget = outer

	case *ast.RangeStmt:
		outer := d.breakTarget
		d.breakTarget = x
		d.findLabels(x.Body)
		d.breakTarget = outer

	case *ast.SelectStmt:
		outer := d.breakTarget
		d.breakTarget = x
		d.findLabels(x.Body)
		d.breakTarget = outer

	case *ast.SwitchStmt:
		outer := d.breakTarget
		d.breakTarget = x
		d.findLabels(x.Body)
		d.breakTarget = outer

	case *ast.TypeSwitchStmt:
		outer := d.breakTarget
		d.breakTarget = x
		d.findLabels(x.Body)
		d.breakTarget = outer

	case *ast.CommClause:
		for _, stmt := range x.Body {
			d.findLabels(stmt)
		}

	case *ast.CaseClause:
		for _, stmt := range x.Body {
			d.findLabels(stmt)
		}
	}
}

// findDead walks the statement looking for dead code.
// If d.reachable is false on entry, stmt itself is dead.
// When findDead returns, d.reachable tells whether the
// statement following stmt is reachable.
func (d *deadState) findDead(stmt ast.Stmt) {
	// Is this a labeled goto target?
	// If so, assume it is reachable due to the goto.
	// This is slightly conservative, in that we don't
	// check that the goto is reachable, so
	//	L: goto L
	// will not provoke a warning.
	// But it's good enough.
	if x, isLabel := stmt.(*ast.LabeledStmt); isLabel && d.hasGoto[x.Label.Name] {
		d.reachable = true
	}

	if !d.reachable {
		switch stmt.(type) {
		case *ast.EmptyStmt:
			// do not warn about unreachable empty statements
		default:
			var (
				inspect    = d.pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
				curStmt, _ = inspect.Root().FindNode(stmt)
				tokFile    = d.pass.Fset.File(stmt.Pos())
			)
			// (This call to pass.Report is a frequent source
			// of diagnostics beyond EOF in a truncated file;
			// see #71659.)
			d.pass.Report(analysis.Diagnostic{
				Pos:     stmt.Pos(),
				End:     stmt.End(),
				Message: "unreachable code",
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   "Remove",
					TextEdits: refactor.DeleteStmt(tokFile, curStmt),
				}},
			})
			d.reachable = true // silence error about next statement
		}
	}

	switch x := stmt.(type) {
	default:
		log.Fatalf("%s: internal error in findDead: unexpected statement %T", d.pass.Fset.Position(x.Pos()), x)

	case *ast.AssignStmt,
		*ast.BadStmt,
		*ast.DeclStmt,
		*ast.DeferStmt,
		*ast.EmptyStmt,
		*ast.GoStmt,
		*ast.IncDecStmt,
		*ast.SendStmt:
		// no control flow

	case *ast.BlockStmt:
		for _, stmt := range x.List {
			d.findDead(stmt)
		}

	case *ast.BranchStmt:
		switch x.Tok {
		case token.BREAK, token.GOTO, token.FALLTHROUGH:
			d.reachable = false
		case token.CONTINUE:
			// NOTE: We accept "continue" statements as terminating.
			// They are not necessary in the spec definition of terminating,
			// because a continue statement cannot be the final statement
			// before a return. But for the more general problem of syntactically
			// identifying dead code, continue redirects control flow just
			// like the other terminating statements.
			d.reachable = false
		}

	case *ast.ExprStmt:
		// Call to panic?
		call, ok := x.X.(*ast.CallExpr)
		if ok {
			name, ok := call.Fun.(*ast.Ident)
			if ok && name.Name == "panic" && name.Obj == nil {
				d.reachable = false
			}
		}

	case *ast.ForStmt:
		d.findDead(x.Body)
		d.reachable = x.Cond != nil || d.hasBreak[x]

	case *ast.IfStmt:
		d.findDead(x.Body)
		if x.Else != nil {
			r := d.reachable
			d.reachable = true
			d.findDead(x.Else)
			d.reachable = d.reachable || r
		} else {
			// might not have executed if statement
			d.reachable = true
		}

	case *ast.LabeledStmt:
		d.findDead(x.Stmt)

	case *ast.RangeStmt:
		d.findDead(x.Body)
		d.reachable = true

	case *ast.ReturnStmt:
		d.reachable = false

	case *ast.SelectStmt:
		// NOTE: Unlike switch and type switch below, we don't care
		// whether a select has a default, because a select without a
		// default blocks until one of the cases can run. That's different
		// from a switch without a default, which behaves like it has
		// a default with an empty body.
		anyReachable := false
		for _, comm := range x.Body.List {
			d.reachable = true
			for _, stmt := range comm.(*ast.CommClause).Body {
				d.findDead(stmt)
			}
			anyReachable = anyReachable || d.reachable
		}
		d.reachable = anyReachable || d.hasBreak[x]

	case *ast.SwitchStmt:
		anyReachable := false
		hasDefault := false
		for _, cas := range x.Body.List {
			cc := cas.(*ast.CaseClause)
			if cc.List == nil {
				hasDefault = true
			}
			d.reachable = true
			for _, stmt := range cc.Body {
				d.findDead(stmt)
			}
			anyReachable = anyReachable || d.reachable
		}
		d.reachable = anyReachable || d.hasBreak[x] || !hasDefault

	case *ast.TypeSwitchStmt:
		anyReachable := false
		hasDefault := false
		for _, cas := range x.Body.List {
			cc := cas.(*ast.CaseClause)
			if cc.List == nil {
				hasDefault = true
			}
			d.reachable = true
			for _, stmt := range cc.Body {
				d.findDead(stmt)
			}
			anyReachable = anyReachable || d.reachable
		}
		d.reachable = anyReachable || d.hasBreak[x] || !hasDefault
	}
}


================================================
FILE: go/analysis/passes/unreachable/unreachable_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unreachable_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/unreachable"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, unreachable.Analyzer, "a")
}


================================================
FILE: go/analysis/passes/unsafeptr/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unsafeptr defines an Analyzer that checks for invalid
// conversions of uintptr to unsafe.Pointer.
//
// # Analyzer unsafeptr
//
// unsafeptr: check for invalid conversions of uintptr to unsafe.Pointer
//
// The unsafeptr analyzer reports likely incorrect uses of unsafe.Pointer
// to convert integers to pointers. A conversion from uintptr to
// unsafe.Pointer is invalid if it implies that there is a uintptr-typed
// word in memory that holds a pointer value, because that word will be
// invisible to stack copying and to the garbage collector.
package unsafeptr


================================================
FILE: go/analysis/passes/unsafeptr/testdata/src/a/a.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"reflect"
	"unsafe"
)

func f() {
	var x unsafe.Pointer
	var y uintptr
	x = unsafe.Pointer(y) // want "possible misuse of unsafe.Pointer"
	y = uintptr(x)

	// only allowed pointer arithmetic is ptr +/-/&^ num.
	// num+ptr is technically okay but still flagged: write ptr+num instead.
	x = unsafe.Pointer(uintptr(x) + 1)
	x = unsafe.Pointer(((uintptr((x))) + 1))
	x = unsafe.Pointer(1 + uintptr(x))          // want "possible misuse of unsafe.Pointer"
	x = unsafe.Pointer(uintptr(x) + uintptr(x)) // want "possible misuse of unsafe.Pointer"
	x = unsafe.Pointer(uintptr(x) - 1)
	x = unsafe.Pointer(1 - uintptr(x)) // want "possible misuse of unsafe.Pointer"
	x = unsafe.Pointer(uintptr(x) &^ 3)
	x = unsafe.Pointer(1 &^ uintptr(x)) // want "possible misuse of unsafe.Pointer"

	// certain uses of reflect are okay
	var v reflect.Value
	x = unsafe.Pointer(v.Pointer())
	x = unsafe.Pointer(v.Pointer() + 1) // want "possible misuse of unsafe.Pointer"
	x = unsafe.Pointer(v.UnsafeAddr())
	x = unsafe.Pointer((v.UnsafeAddr()))
	var s1 *reflect.StringHeader
	x = unsafe.Pointer(s1.Data)
	x = unsafe.Pointer(s1.Data + 1) // want "possible misuse of unsafe.Pointer"
	var s2 *reflect.SliceHeader
	x = unsafe.Pointer(s2.Data)
	var s3 reflect.StringHeader
	x = unsafe.Pointer(s3.Data) // want "possible misuse of unsafe.Pointer"
	var s4 reflect.SliceHeader
	x = unsafe.Pointer(s4.Data) // want "possible misuse of unsafe.Pointer"

	// but only in reflect
	var vv V
	x = unsafe.Pointer(vv.Pointer())    // want "possible misuse of unsafe.Pointer"
	x = unsafe.Pointer(vv.UnsafeAddr()) // want "possible misuse of unsafe.Pointer"
	var ss1 *StringHeader
	x = unsafe.Pointer(ss1.Data) // want "possible misuse of unsafe.Pointer"
	var ss2 *SliceHeader
	x = unsafe.Pointer(ss2.Data) // want "possible misuse of unsafe.Pointer"

}

type V interface {
	Pointer() uintptr
	UnsafeAddr() uintptr
}

type StringHeader struct {
	Data uintptr
}

type SliceHeader struct {
	Data uintptr
}


================================================
FILE: go/analysis/passes/unsafeptr/testdata/src/a/issue40701.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"reflect"
	"unsafe"
)

// Explicitly allocating a variable of type reflect.SliceHeader.
func _(p *byte, n int) []byte {
	var sh reflect.SliceHeader
	sh.Data = uintptr(unsafe.Pointer(p))
	sh.Len = n
	sh.Cap = n
	return *(*[]byte)(unsafe.Pointer(&sh)) // want "possible misuse of reflect.SliceHeader"
}

// Implicitly allocating a variable of type reflect.SliceHeader.
func _(p *byte, n int) []byte {
	return *(*[]byte)(unsafe.Pointer(&reflect.SliceHeader{ // want "possible misuse of reflect.SliceHeader"
		Data: uintptr(unsafe.Pointer(p)),
		Len:  n,
		Cap:  n,
	}))
}

// Use reflect.StringHeader as a composite literal value.
func _(p *byte, n int) []byte {
	var res []byte
	*(*reflect.StringHeader)(unsafe.Pointer(&res)) = reflect.StringHeader{ // want "possible misuse of reflect.StringHeader"
		Data: uintptr(unsafe.Pointer(p)),
		Len:  n,
	}
	return res
}

func _() {
	// don't crash when obj.Pkg() == nil
	var err error
	_ = &err
}


================================================
FILE: go/analysis/passes/unsafeptr/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import "unsafe"

func _[IntPtr ~uintptr, RealPtr *T, AnyPtr uintptr | *T, T any]() {
	var (
		i IntPtr
		r RealPtr
		a AnyPtr
	)
	_ = unsafe.Pointer(i)          // incorrect, but not detected
	_ = unsafe.Pointer(i + i)      // incorrect, but not detected
	_ = unsafe.Pointer(1 + i)      // incorrect, but not detected
	_ = unsafe.Pointer(uintptr(i)) // want "possible misuse of unsafe.Pointer"
	_ = unsafe.Pointer(r)
	_ = unsafe.Pointer(a) // possibly incorrect, but not detected
}


================================================
FILE: go/analysis/passes/unsafeptr/unsafeptr.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unsafeptr defines an Analyzer that checks for invalid
// conversions of uintptr to unsafe.Pointer.
package unsafeptr

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "unsafeptr",
	Doc:      analyzerutil.MustExtractDoc(doc, "unsafeptr"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unsafeptr",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
		(*ast.StarExpr)(nil),
		(*ast.UnaryExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		switch x := n.(type) {
		case *ast.CallExpr:
			if len(x.Args) == 1 &&
				hasBasicType(pass.TypesInfo, x.Fun, types.UnsafePointer) &&
				hasBasicType(pass.TypesInfo, x.Args[0], types.Uintptr) &&
				!isSafeUintptr(pass.TypesInfo, x.Args[0]) {
				pass.ReportRangef(x, "possible misuse of unsafe.Pointer")
			}
		case *ast.StarExpr:
			if t := pass.TypesInfo.Types[x].Type; isReflectHeader(t) {
				pass.ReportRangef(x, "possible misuse of %s", t)
			}
		case *ast.UnaryExpr:
			if x.Op != token.AND {
				return
			}
			if t := pass.TypesInfo.Types[x.X].Type; isReflectHeader(t) {
				pass.ReportRangef(x, "possible misuse of %s", t)
			}
		}
	})
	return nil, nil
}

// isSafeUintptr reports whether x - already known to be a uintptr -
// is safe to convert to unsafe.Pointer.
func isSafeUintptr(info *types.Info, x ast.Expr) bool {
	// Check unsafe.Pointer safety rules according to
	// https://golang.org/pkg/unsafe/#Pointer.

	switch x := ast.Unparen(x).(type) {
	case *ast.SelectorExpr:
		// "(6) Conversion of a reflect.SliceHeader or
		// reflect.StringHeader Data field to or from Pointer."
		if x.Sel.Name != "Data" {
			break
		}
		// reflect.SliceHeader and reflect.StringHeader are okay,
		// but only if they are pointing at a real slice or string.
		// It's not okay to do:
		//	var x SliceHeader
		//	x.Data = uintptr(unsafe.Pointer(...))
		//	... use x ...
		//	p := unsafe.Pointer(x.Data)
		// because in the middle the garbage collector doesn't
		// see x.Data as a pointer and so x.Data may be dangling
		// by the time we get to the conversion at the end.
		// For now approximate by saying that *Header is okay
		// but Header is not.
		pt, ok := types.Unalias(info.Types[x.X].Type).(*types.Pointer)
		if ok && isReflectHeader(pt.Elem()) {
			return true
		}

	case *ast.CallExpr:
		// "(5) Conversion of the result of reflect.Value.Pointer or
		// reflect.Value.UnsafeAddr from uintptr to Pointer."
		if len(x.Args) != 0 {
			break
		}
		sel, ok := x.Fun.(*ast.SelectorExpr)
		if !ok {
			break
		}
		switch sel.Sel.Name {
		case "Pointer", "UnsafeAddr":
			if typesinternal.IsTypeNamed(info.Types[sel.X].Type, "reflect", "Value") {
				return true
			}
		}
	}

	// "(3) Conversion of a Pointer to a uintptr and back, with arithmetic."
	return isSafeArith(info, x)
}

// isSafeArith reports whether x is a pointer arithmetic expression that is safe
// to convert to unsafe.Pointer.
func isSafeArith(info *types.Info, x ast.Expr) bool {
	switch x := ast.Unparen(x).(type) {
	case *ast.CallExpr:
		// Base case: initial conversion from unsafe.Pointer to uintptr.
		return len(x.Args) == 1 &&
			hasBasicType(info, x.Fun, types.Uintptr) &&
			hasBasicType(info, x.Args[0], types.UnsafePointer)

	case *ast.BinaryExpr:
		// "It is valid both to add and to subtract offsets from a
		// pointer in this way. It is also valid to use &^ to round
		// pointers, usually for alignment."
		switch x.Op {
		case token.ADD, token.SUB, token.AND_NOT:
			// TODO(mdempsky): Match compiler
			// semantics. ADD allows a pointer on either
			// side; SUB and AND_NOT don't care about RHS.
			return isSafeArith(info, x.X) && !isSafeArith(info, x.Y)
		}
	}

	return false
}

// hasBasicType reports whether x's type is a types.Basic with the given kind.
func hasBasicType(info *types.Info, x ast.Expr, kind types.BasicKind) bool {
	t := info.Types[x].Type
	if t != nil {
		t = t.Underlying()
	}
	b, ok := t.(*types.Basic)
	return ok && b.Kind() == kind
}

// isReflectHeader reports whether t is reflect.SliceHeader or reflect.StringHeader.
func isReflectHeader(t types.Type) bool {
	return typesinternal.IsTypeNamed(t, "reflect", "SliceHeader", "StringHeader")
}


================================================
FILE: go/analysis/passes/unsafeptr/unsafeptr_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unsafeptr_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/unsafeptr"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, unsafeptr.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/unusedresult/cmd/unusedresult/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The unusedresult command applies the golang.org/x/tools/go/analysis/passes/unusedresult
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/unusedresult"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(unusedresult.Analyzer) }


================================================
FILE: go/analysis/passes/unusedresult/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedresult defines an analyzer that checks for unused
// results of calls to certain pure functions.
//
// # Analyzer unusedresult
//
// unusedresult: check for unused results of calls to some functions
//
// Some functions like fmt.Errorf return a result and have no side
// effects, so it is always a mistake to discard the result. Other
// functions may return an error that must not be ignored, or a cleanup
// operation that must be called. This analyzer reports calls to
// functions like these when the result of the call is ignored.
//
// The set of functions may be controlled using flags.
package unusedresult


================================================
FILE: go/analysis/passes/unusedresult/testdata/src/a/a.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"bytes"
	"errors"
	"fmt"
	. "fmt"
)

func _() {
	fmt.Errorf("") // want "result of fmt.Errorf call not used"
	_ = fmt.Errorf("")

	errors.New("") // want "result of errors.New call not used"

	err := errors.New("")
	err.Error() // want `result of \(error\).Error call not used`

	var buf bytes.Buffer
	buf.String() // want `result of \(\*bytes.Buffer\).String call not used`

	fmt.Sprint("")  // want "result of fmt.Sprint call not used"
	fmt.Sprintf("") // want "result of fmt.Sprintf call not used"

	Sprint("")  // want "result of fmt.Sprint call not used"
	Sprintf("") // want "result of fmt.Sprintf call not used"
}


================================================
FILE: go/analysis/passes/unusedresult/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"bytes"
	"errors"
	"fmt"
	"typeparams/userdefs"
)

func _[T any]() {
	fmt.Errorf("") // want "result of fmt.Errorf call not used"
	_ = fmt.Errorf("")

	errors.New("") // want "result of errors.New call not used"

	err := errors.New("")
	err.Error() // want `result of \(error\).Error call not used`

	var buf bytes.Buffer
	buf.String() // want `result of \(\*bytes.Buffer\).String call not used`

	fmt.Sprint("")  // want "result of fmt.Sprint call not used"
	fmt.Sprintf("") // want "result of fmt.Sprintf call not used"

	userdefs.MustUse[int](1) // want "result of typeparams/userdefs.MustUse call not used"
	_ = userdefs.MustUse[int](2)

	s := userdefs.SingleTypeParam[int]{X: 1}
	s.String() // want `result of \(\*typeparams/userdefs.SingleTypeParam\[int\]\).String call not used`
	_ = s.String()

	m := userdefs.MultiTypeParam[int, string]{X: 1, Y: "one"}
	m.String() // want `result of \(\*typeparams/userdefs.MultiTypeParam\[int, string\]\).String call not used`
	_ = m.String()
}


================================================
FILE: go/analysis/passes/unusedresult/testdata/src/typeparams/userdefs/userdefs.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package userdefs

func MustUse[T interface{ ~int }](v T) T {
	return v + 1
}

type SingleTypeParam[T any] struct {
	X T
}

func (_ *SingleTypeParam[T]) String() string {
	return "SingleTypeParam"
}

type MultiTypeParam[T any, U any] struct {
	X T
	Y U
}

func (_ *MultiTypeParam[T, U]) String() string {
	return "MultiTypeParam"
}


================================================
FILE: go/analysis/passes/unusedresult/unusedresult.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedresult defines an analyzer that checks for unused
// results of calls to certain functions.
package unusedresult

// It is tempting to make this analysis inductive: for each function
// that tail-calls one of the functions that we check, check those
// functions too. However, just because you must use the result of
// fmt.Sprintf doesn't mean you need to use the result of every
// function that returns a formatted string: it may have other results
// and effects.

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"
	"sort"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "unusedresult",
	Doc:      analyzerutil.MustExtractDoc(doc, "unusedresult"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedresult",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

// flags
var funcs, stringMethods stringSetFlag

func init() {
	// TODO(adonovan): provide a comment or declaration syntax to
	// allow users to add their functions to this set using facts.
	// For example:
	//
	//    func ignoringTheErrorWouldBeVeryBad() error {
	//      type mustUseResult struct{} // enables vet unusedresult check
	//      ...
	//    }
	//
	//    ignoringTheErrorWouldBeVeryBad() // oops
	//

	// List standard library functions here.
	// The context.With{Cancel,Deadline,Timeout} entries are
	// effectively redundant wrt the lostcancel analyzer.
	funcs = stringSetFlag{
		"context.WithCancel":      true,
		"context.WithDeadline":    true,
		"context.WithTimeout":     true,
		"context.WithValue":       true,
		"errors.New":              true,
		"fmt.Append":              true,
		"fmt.Appendf":             true,
		"fmt.Appendln":            true,
		"fmt.Errorf":              true,
		"fmt.Sprint":              true,
		"fmt.Sprintf":             true,
		"fmt.Sprintln":            true,
		"maps.All":                true,
		"maps.Clone":              true,
		"maps.Collect":            true,
		"maps.Equal":              true,
		"maps.EqualFunc":          true,
		"maps.Keys":               true,
		"maps.Values":             true,
		"slices.All":              true,
		"slices.AppendSeq":        true,
		"slices.Backward":         true,
		"slices.BinarySearch":     true,
		"slices.BinarySearchFunc": true,
		"slices.Chunk":            true,
		"slices.Clip":             true,
		"slices.Clone":            true,
		"slices.Collect":          true,
		"slices.Compact":          true,
		"slices.CompactFunc":      true,
		"slices.Compare":          true,
		"slices.CompareFunc":      true,
		"slices.Concat":           true,
		"slices.Contains":         true,
		"slices.ContainsFunc":     true,
		"slices.Delete":           true,
		"slices.DeleteFunc":       true,
		"slices.Equal":            true,
		"slices.EqualFunc":        true,
		"slices.Grow":             true,
		"slices.Index":            true,
		"slices.IndexFunc":        true,
		"slices.Insert":           true,
		"slices.IsSorted":         true,
		"slices.IsSortedFunc":     true,
		"slices.Max":              true,
		"slices.MaxFunc":          true,
		"slices.Min":              true,
		"slices.MinFunc":          true,
		"slices.Repeat":           true,
		"slices.Replace":          true,
		"slices.Sorted":           true,
		"slices.SortedFunc":       true,
		"slices.SortedStableFunc": true,
		"slices.Values":           true,
		"sort.Reverse":            true,
	}
	Analyzer.Flags.Var(&funcs, "funcs",
		"comma-separated list of functions whose results must be used")

	stringMethods.Set("Error,String")
	Analyzer.Flags.Var(&stringMethods, "stringmethods",
		"comma-separated list of names of methods of type func() string whose results must be used")
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// Split functions into (pkg, name) pairs to save allocation later.
	pkgFuncs := make(map[[2]string]bool, len(funcs))
	for s := range funcs {
		if i := strings.LastIndexByte(s, '.'); i > 0 {
			pkgFuncs[[2]string{s[:i], s[i+1:]}] = true
		}
	}

	nodeFilter := []ast.Node{
		(*ast.ExprStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		call, ok := ast.Unparen(n.(*ast.ExprStmt).X).(*ast.CallExpr)
		if !ok {
			return // not a call statement
		}

		// Call to function or method?
		fn, ok := typeutil.Callee(pass.TypesInfo, call).(*types.Func)
		if !ok {
			return // e.g. var or builtin
		}
		if sig := fn.Signature(); sig.Recv() != nil {
			// method (e.g. foo.String())
			if types.Identical(sig, sigNoArgsStringResult) {
				if stringMethods[fn.Name()] {
					pass.ReportRangef(astutil.RangeOf(call.Pos(), call.Lparen),
						"result of (%s).%s call not used",
						sig.Recv().Type(), fn.Name())
				}
			}
		} else {
			// package-level function (e.g. fmt.Errorf)
			if pkgFuncs[[2]string{fn.Pkg().Path(), fn.Name()}] {
				pass.ReportRangef(astutil.RangeOf(call.Pos(), call.Lparen),
					"result of %s.%s call not used",
					fn.Pkg().Path(), fn.Name())
			}
		}
	})
	return nil, nil
}

// func() string
var sigNoArgsStringResult = types.NewSignatureType(nil, nil, nil, nil, types.NewTuple(types.NewParam(token.NoPos, nil, "", types.Typ[types.String])), false)

type stringSetFlag map[string]bool

func (ss *stringSetFlag) String() string {
	var items []string
	for item := range *ss {
		items = append(items, item)
	}
	sort.Strings(items)
	return strings.Join(items, ",")
}

func (ss *stringSetFlag) Set(s string) error {
	m := make(map[string]bool) // clobber previous value
	if s != "" {
		for name := range strings.SplitSeq(s, ",") {
			if name == "" {
				continue // TODO: report error? proceed?
			}
			m[name] = true
		}
	}
	*ss = m
	return nil
}


================================================
FILE: go/analysis/passes/unusedresult/unusedresult_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedresult_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/unusedresult"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	funcs := "typeparams/userdefs.MustUse,errors.New,fmt.Errorf,fmt.Sprintf,fmt.Sprint"
	unusedresult.Analyzer.Flags.Set("funcs", funcs)
	analysistest.Run(t, testdata, unusedresult.Analyzer, "a", "typeparams")
}


================================================
FILE: go/analysis/passes/unusedwrite/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedwrite checks for unused writes to the elements of a struct or array object.
//
// # Analyzer unusedwrite
//
// unusedwrite: checks for unused writes
//
// The analyzer reports instances of writes to struct fields and
// arrays that are never read. Specifically, when a struct object
// or an array is copied, its elements are copied implicitly by
// the compiler, and any element write to this copy does nothing
// with the original object.
//
// For example:
//
//	type T struct { x int }
//
//	func f(input []T) {
//		for i, v := range input {  // v is a copy
//			v.x = i  // unused write to field x
//		}
//	}
//
// Another example is about non-pointer receiver:
//
//	type T struct { x int }
//
//	func (t T) f() {  // t is a copy
//		t.x = i  // unused write to field x
//	}
package unusedwrite


================================================
FILE: go/analysis/passes/unusedwrite/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The unusedwrite command runs the unusedwrite analyzer
// on the specified packages.
package main

import (
	"golang.org/x/tools/go/analysis/passes/unusedwrite"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(unusedwrite.Analyzer) }


================================================
FILE: go/analysis/passes/unusedwrite/testdata/src/a/unusedwrite.go
================================================
package a

type T1 struct{ x int }

type T2 struct {
	x int
	y int
}

type T3 struct{ y *T1 }

func BadWrites() {
	// Test struct field writes.
	var s1 T1
	s1.x = 10 // want "unused write to field x"

	// Test array writes.
	var s2 [10]int
	s2[1] = 10 // want "unused write to array index 1:int"

	// Test range variables of struct type.
	s3 := []T1{T1{x: 100}}
	for i, v := range s3 {
		v.x = i // want "unused write to field x"
	}

	// Test the case where a different field is read after the write.
	s4 := []T2{T2{x: 1, y: 2}}
	for i, v := range s4 {
		v.x = i // want "unused write to field x"
		_ = v.y
	}

	// The analyzer can handle only simple control flow.
	type T struct{ x, y int }
	t := new(T)
	if true {
		t = new(T)
	} // causes t below to become phi(alloc, alloc), not a simple alloc
	t.x = 1 // false negative
	print(t.y)
}

func (t T1) BadValueReceiverWrite(v T2) {
	t.x = 10 // want "unused write to field x"
	v.y = 20 // want "unused write to field y"
}

func GoodWrites(m map[int]int) {
	// A map is copied by reference such that a write will affect the original map.
	m[1] = 10

	// Test struct field writes.
	var s1 T1
	s1.x = 10
	print(s1.x)

	// Test array writes.
	var s2 [10]int
	s2[1] = 10
	// Current the checker doesn't distinguish index 1 and index 2.
	_ = s2[2]

	// Test range variables of struct type.
	s3 := []T1{T1{x: 100}}
	for i, v := range s3 { // v is a copy
		v.x = i
		_ = v.x // still a usage
	}

	// Test an object with multiple fields.
	o := &T2{x: 10, y: 20}
	print(o)

	// Test an object of embedded struct/pointer type.
	t1 := &T1{x: 10}
	t2 := &T3{y: t1}
	print(t2)
}

func (t *T1) GoodPointerReceiverWrite(v *T2) {
	t.x = 10
	v.y = 20
}


================================================
FILE: go/analysis/passes/unusedwrite/testdata/src/importsunsafe/i.go
================================================
package importsunsafe

import "unsafe"

type S struct {
	F, G int
}

func _() {
	var s S
	s.F = 1
	// This write to G is used below, because &s.F allows access to all of s, but
	// the analyzer would naively report it as unused. For this reason, we
	// silence the analysis if unsafe is imported.
	s.G = 2

	ptr := unsafe.Pointer(&s.F)
	t := (*S)(ptr)
	println(t.G)
}


================================================
FILE: go/analysis/passes/unusedwrite/unusedwrite.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedwrite

import (
	_ "embed"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/buildssa"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typeparams"
)

//go:embed doc.go
var doc string

// Analyzer reports instances of writes to struct fields and arrays
// that are never read.
var Analyzer = &analysis.Analyzer{
	Name:     "unusedwrite",
	Doc:      analyzerutil.MustExtractDoc(doc, "unusedwrite"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedwrite",
	Requires: []*analysis.Analyzer{buildssa.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	for _, pkg := range pass.Pkg.Imports() {
		if pkg.Path() == "unsafe" {
			// See golang/go#67684, or testdata/src/importsunsafe: the unusedwrite
			// analyzer may have false positives when used with unsafe.
			return nil, nil
		}
	}

	ssainput := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
	for _, fn := range ssainput.SrcFuncs {
		reports := checkStores(fn)
		for _, store := range reports {
			switch addr := store.Addr.(type) {
			case *ssa.FieldAddr:
				field := typeparams.CoreType(typeparams.MustDeref(addr.X.Type())).(*types.Struct).Field(addr.Field)
				pass.Reportf(store.Pos(),
					"unused write to field %s", field.Name())
			case *ssa.IndexAddr:
				pass.Reportf(store.Pos(),
					"unused write to array index %s", addr.Index)
			}
		}
	}
	return nil, nil
}

// checkStores returns *Stores in fn whose address is written to but never used.
func checkStores(fn *ssa.Function) []*ssa.Store {
	var reports []*ssa.Store
	// Visit each block. No need to visit fn.Recover.
	for _, blk := range fn.Blocks {
		for _, instr := range blk.Instrs {
			// Identify writes.
			if store, ok := instr.(*ssa.Store); ok {
				// Consider field/index writes to an object whose elements are copied and not shared.
				// MapUpdate is excluded since only the reference of the map is copied.
				switch addr := store.Addr.(type) {
				case *ssa.FieldAddr:
					if isDeadStore(store, addr.X, addr) {
						reports = append(reports, store)
					}
				case *ssa.IndexAddr:
					if isDeadStore(store, addr.X, addr) {
						reports = append(reports, store)
					}
				}
			}
		}
	}
	return reports
}

// isDeadStore determines whether a field/index write to an object is dead.
// Argument "obj" is the object, and "addr" is the instruction fetching the field/index.
func isDeadStore(store *ssa.Store, obj ssa.Value, addr ssa.Instruction) bool {
	// Consider only struct or array objects.
	if !hasStructOrArrayType(obj) {
		return false
	}
	// Check liveness: if the value is used later, then don't report the write.
	for _, ref := range *obj.Referrers() {
		if ref == store || ref == addr {
			continue
		}
		switch ins := ref.(type) {
		case ssa.CallInstruction:
			return false
		case *ssa.FieldAddr:
			// Check whether the same field is used.
			if ins.X == obj {
				if faddr, ok := addr.(*ssa.FieldAddr); ok {
					if faddr.Field == ins.Field {
						return false
					}
				}
			}
			// Otherwise another field is used, and this usage doesn't count.
			continue
		case *ssa.IndexAddr:
			if ins.X == obj {
				return false
			}
			continue // Otherwise another object is used
		case *ssa.Lookup:
			if ins.X == obj {
				return false
			}
			continue // Otherwise another object is used
		case *ssa.Store:
			if ins.Val == obj {
				return false
			}
			continue // Otherwise other object is stored
		default: // consider live if the object is used in any other instruction
			return false
		}
	}
	return true
}

// isStructOrArray returns whether the underlying type is struct or array.
func isStructOrArray(tp types.Type) bool {
	switch tp.Underlying().(type) {
	case *types.Array:
		return true
	case *types.Struct:
		return true
	}
	return false
}

// hasStructOrArrayType returns whether a value is of struct or array type.
func hasStructOrArrayType(v ssa.Value) bool {
	if instr, ok := v.(ssa.Instruction); ok {
		if alloc, ok := instr.(*ssa.Alloc); ok {
			// Check the element type of an allocated register (which always has pointer type)
			// e.g., for
			//   func (t T) f() { ...}
			// the receiver object is of type *T:
			//   t0 = local T (t)   *T
			if tp, ok := types.Unalias(alloc.Type()).(*types.Pointer); ok {
				return isStructOrArray(tp.Elem())
			}
			return false
		}
	}
	return isStructOrArray(v.Type())
}


================================================
FILE: go/analysis/passes/unusedwrite/unusedwrite_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedwrite_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/unusedwrite"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, unusedwrite.Analyzer, "a", "importsunsafe")
}


================================================
FILE: go/analysis/passes/usesgenerics/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package usesgenerics defines an Analyzer that checks for usage of generic
// features added in Go 1.18.
//
// # Analyzer usesgenerics
//
// usesgenerics: detect whether a package uses generics features
//
// The usesgenerics analysis reports whether a package directly or transitively
// uses certain features associated with generic programming in Go.
package usesgenerics


================================================
FILE: go/analysis/passes/usesgenerics/testdata/src/a/a.go
================================================
// want package:`features{typeDecl,funcDecl,funcInstance}`

package a

type T[P any] int

func F[P any]() {}

var _ = F[int]


================================================
FILE: go/analysis/passes/usesgenerics/testdata/src/b/b.go
================================================
// want package:`features{typeSet}`

package b

type Constraint interface {
	~int | string
}


================================================
FILE: go/analysis/passes/usesgenerics/testdata/src/c/c.go
================================================
// want package:`features{typeDecl,funcDecl,typeSet,typeInstance,funcInstance}`

// Features funcDecl, typeSet, and funcInstance come from imported packages "a"
// and "b". These features are not directly present in "c".

package c

import (
	"a"
	"b"
)

type T[P b.Constraint] a.T[P]


================================================
FILE: go/analysis/passes/usesgenerics/testdata/src/d/d.go
================================================
// want package:`features{typeSet}`

package d

type myInt int

func _() {
	// Sanity check that we can both detect local types and interfaces with
	// embedded defined types.
	type constraint interface {
		myInt
	}
}


================================================
FILE: go/analysis/passes/usesgenerics/usesgenerics.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package usesgenerics

import (
	_ "embed"
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typeparams/genericfeatures"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:       "usesgenerics",
	Doc:        analyzerutil.MustExtractDoc(doc, "usesgenerics"),
	URL:        "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/usesgenerics",
	Requires:   []*analysis.Analyzer{inspect.Analyzer},
	Run:        run,
	ResultType: reflect.TypeFor[*Result](),
	FactTypes:  []analysis.Fact{new(featuresFact)},
}

type Features = genericfeatures.Features

const (
	GenericTypeDecls  = genericfeatures.GenericTypeDecls
	GenericFuncDecls  = genericfeatures.GenericFuncDecls
	EmbeddedTypeSets  = genericfeatures.EmbeddedTypeSets
	TypeInstantiation = genericfeatures.TypeInstantiation
	FuncInstantiation = genericfeatures.FuncInstantiation
)

// Result is the usesgenerics analyzer result type. The Direct field records
// features used directly by the package being analyzed (i.e. contained in the
// package source code). The Transitive field records any features used by the
// package or any of its transitive imports.
type Result struct {
	Direct, Transitive Features
}

type featuresFact struct {
	Features Features
}

func (f *featuresFact) AFact()         {}
func (f *featuresFact) String() string { return f.Features.String() }

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	direct := genericfeatures.ForPackage(inspect, pass.TypesInfo)

	transitive := direct | importedTransitiveFeatures(pass)
	if transitive != 0 {
		pass.ExportPackageFact(&featuresFact{transitive})
	}

	return &Result{
		Direct:     direct,
		Transitive: transitive,
	}, nil
}

// importedTransitiveFeatures computes features that are used transitively via
// imports.
func importedTransitiveFeatures(pass *analysis.Pass) Features {
	var feats Features
	for _, imp := range pass.Pkg.Imports() {
		var importedFact featuresFact
		if pass.ImportPackageFact(imp, &importedFact) {
			feats |= importedFact.Features
		}
	}
	return feats
}


================================================
FILE: go/analysis/passes/usesgenerics/usesgenerics_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package usesgenerics_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/usesgenerics"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, usesgenerics.Analyzer, "a", "b", "c", "d")
}


================================================
FILE: go/analysis/passes/waitgroup/doc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package waitgroup defines an Analyzer that detects simple misuses
// of sync.WaitGroup.
//
// # Analyzer waitgroup
//
// waitgroup: check for misuses of sync.WaitGroup
//
// This analyzer detects mistaken calls to the (*sync.WaitGroup).Add
// method from inside a new goroutine, causing Add to race with Wait:
//
//	// WRONG
//	var wg sync.WaitGroup
//	go func() {
//	        wg.Add(1) // "WaitGroup.Add called from inside new goroutine"
//	        defer wg.Done()
//	        ...
//	}()
//	wg.Wait() // (may return prematurely before new goroutine starts)
//
// The correct code calls Add before starting the goroutine:
//
//	// RIGHT
//	var wg sync.WaitGroup
//	wg.Add(1)
//	go func() {
//		defer wg.Done()
//		...
//	}()
//	wg.Wait()
package waitgroup


================================================
FILE: go/analysis/passes/waitgroup/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The waitgroup command applies the golang.org/x/tools/go/analysis/passes/waitgroup
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/waitgroup"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(waitgroup.Analyzer) }


================================================
FILE: go/analysis/passes/waitgroup/testdata/src/a/a.go
================================================
package a

import "sync"

func f() {
	var wg sync.WaitGroup
	wg.Add(1) // ok
	go func() {
		wg.Add(1) // want "WaitGroup.Add called from inside new goroutine"
		// ...
		wg.Add(1) // ok
	}()
	wg.Add(1) // ok
}


================================================
FILE: go/analysis/passes/waitgroup/waitgroup.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package waitgroup defines an Analyzer that detects simple misuses
// of sync.WaitGroup.
package waitgroup

import (
	_ "embed"
	"go/ast"
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "waitgroup",
	Doc:      analyzerutil.MustExtractDoc(doc, "waitgroup"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/waitgroup",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	if !typesinternal.Imports(pass.Pkg, "sync") {
		return nil, nil // doesn't directly import sync
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.CallExpr)(nil),
	}

	inspect.WithStack(nodeFilter, func(n ast.Node, push bool, stack []ast.Node) (proceed bool) {
		if push {
			call := n.(*ast.CallExpr)
			obj := typeutil.Callee(pass.TypesInfo, call)
			if typesinternal.IsMethodNamed(obj, "sync", "WaitGroup", "Add") &&
				hasSuffix(stack, wantSuffix) &&
				backindex(stack, 1) == backindex(stack, 2).(*ast.BlockStmt).List[0] { // ExprStmt must be Block's first stmt

				pass.Reportf(call.Lparen, "WaitGroup.Add called from inside new goroutine")
			}
		}
		return true
	})

	return nil, nil
}

//	go func() {
//	   wg.Add(1)
//	   ...
//	}()
var wantSuffix = []ast.Node{
	(*ast.GoStmt)(nil),
	(*ast.CallExpr)(nil),
	(*ast.FuncLit)(nil),
	(*ast.BlockStmt)(nil),
	(*ast.ExprStmt)(nil),
	(*ast.CallExpr)(nil),
}

// hasSuffix reports whether stack has the matching suffix,
// considering only node types.
func hasSuffix(stack, suffix []ast.Node) bool {
	// TODO(adonovan): the inspector could implement this for us.
	if len(stack) < len(suffix) {
		return false
	}
	for i := range len(suffix) {
		if reflect.TypeOf(backindex(stack, i)) != reflect.TypeOf(backindex(suffix, i)) {
			return false
		}
	}
	return true
}

// backindex is like [slices.Index] but from the back of the slice.
func backindex[T any](slice []T, i int) T {
	return slice[len(slice)-1-i]
}


================================================
FILE: go/analysis/passes/waitgroup/waitgroup_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package waitgroup_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/waitgroup"
)

func Test(t *testing.T) {
	analysistest.Run(t, analysistest.TestData(), waitgroup.Analyzer, "a")
}


================================================
FILE: go/analysis/singlechecker/singlechecker.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package singlechecker defines the main function for an analysis
// driver with only a single analysis.
// This package makes it easy for a provider of an analysis package to
// also provide a standalone tool that runs just that analysis.
//
// For example, if example.org/findbadness is an analysis package,
// all that is needed to define a standalone tool is a file,
// example.org/findbadness/cmd/findbadness/main.go, containing:
//
//	// The findbadness command runs an analysis.
//	package main
//
//	import (
//		"example.org/findbadness"
//		"golang.org/x/tools/go/analysis/singlechecker"
//	)
//
//	func main() { singlechecker.Main(findbadness.Analyzer) }
package singlechecker

import (
	"flag"
	"fmt"
	"log"
	"os"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/go/analysis/internal/checker"
	"golang.org/x/tools/go/analysis/unitchecker"
)

// Main is the main function for a checker command for a single analysis.
func Main(a *analysis.Analyzer) {
	log.SetFlags(0)
	log.SetPrefix(a.Name + ": ")

	analyzers := []*analysis.Analyzer{a}

	if err := analysis.Validate(analyzers); err != nil {
		log.Fatal(err)
	}

	checker.RegisterFlags()

	flag.Usage = func() {
		paras := strings.Split(a.Doc, "\n\n")
		fmt.Fprintf(os.Stderr, "%s: %s\n\n", a.Name, paras[0])
		fmt.Fprintf(os.Stderr, "Usage: %s [-flag] [package]\n\n", a.Name)
		if len(paras) > 1 {
			fmt.Fprintln(os.Stderr, strings.Join(paras[1:], "\n\n"))
		}
		fmt.Fprintln(os.Stderr, "\nFlags:")
		flag.PrintDefaults()
	}

	analyzers = analysisflags.Parse(analyzers, false)

	args := flag.Args()
	if len(args) == 0 {
		flag.Usage()
		os.Exit(1)
	}

	if len(args) == 1 && strings.HasSuffix(args[0], ".cfg") {
		unitchecker.Run(args[0], analyzers)
		panic("unreachable")
	}

	os.Exit(checker.Run(args, analyzers))
}


================================================
FILE: go/analysis/unitchecker/export_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unitchecker

import (
	"go/token"
	"go/types"
)

// This file exposes various internal hooks to the separate_test.
//
// TODO(adonovan): expose a public API to unitchecker that doesn't
// rely on details of JSON .cfg files or enshrine I/O decisions or
// assumptions about how "go vet" locates things. Ideally the new Run
// function would accept an interface, and a Config file would be just
// one way--the go vet way--to implement it.

func SetTypeImportExport(
	MakeTypesImporter func(*Config, *token.FileSet) types.Importer,
	ExportTypes func(*Config, *token.FileSet, *types.Package) error,
) {
	makeTypesImporter = MakeTypesImporter
	exportTypes = ExportTypes
}


================================================
FILE: go/analysis/unitchecker/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// This file provides an example command for static checkers
// conforming to the golang.org/x/tools/go/analysis API.
// It serves as a model for the behavior of the cmd/vet tool in $GOROOT.
// Being based on the unitchecker driver, it must be run by go vet:
//
//	$ go build -o unitchecker main.go
//	$ go vet -vettool=unitchecker my/project/...
//
// For a checker also capable of running standalone, use multichecker.
package main

import (
	"golang.org/x/tools/go/analysis/unitchecker"

	"golang.org/x/tools/go/analysis/passes/appends"
	"golang.org/x/tools/go/analysis/passes/asmdecl"
	"golang.org/x/tools/go/analysis/passes/assign"
	"golang.org/x/tools/go/analysis/passes/atomic"
	"golang.org/x/tools/go/analysis/passes/bools"
	"golang.org/x/tools/go/analysis/passes/buildtag"
	"golang.org/x/tools/go/analysis/passes/cgocall"
	"golang.org/x/tools/go/analysis/passes/composite"
	"golang.org/x/tools/go/analysis/passes/copylock"
	"golang.org/x/tools/go/analysis/passes/directive"
	"golang.org/x/tools/go/analysis/passes/errorsas"
	"golang.org/x/tools/go/analysis/passes/framepointer"
	"golang.org/x/tools/go/analysis/passes/httpresponse"
	"golang.org/x/tools/go/analysis/passes/ifaceassert"
	"golang.org/x/tools/go/analysis/passes/loopclosure"
	"golang.org/x/tools/go/analysis/passes/lostcancel"
	"golang.org/x/tools/go/analysis/passes/nilfunc"
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/passes/shift"
	"golang.org/x/tools/go/analysis/passes/sigchanyzer"
	"golang.org/x/tools/go/analysis/passes/stdmethods"
	"golang.org/x/tools/go/analysis/passes/stringintconv"
	"golang.org/x/tools/go/analysis/passes/structtag"
	"golang.org/x/tools/go/analysis/passes/testinggoroutine"
	"golang.org/x/tools/go/analysis/passes/tests"
	"golang.org/x/tools/go/analysis/passes/timeformat"
	"golang.org/x/tools/go/analysis/passes/unmarshal"
	"golang.org/x/tools/go/analysis/passes/unreachable"
	"golang.org/x/tools/go/analysis/passes/unsafeptr"
	"golang.org/x/tools/go/analysis/passes/unusedresult"
)

func main() {
	unitchecker.Main(
		appends.Analyzer,
		asmdecl.Analyzer,
		assign.Analyzer,
		atomic.Analyzer,
		bools.Analyzer,
		buildtag.Analyzer,
		cgocall.Analyzer,
		composite.Analyzer,
		copylock.Analyzer,
		directive.Analyzer,
		errorsas.Analyzer,
		framepointer.Analyzer,
		httpresponse.Analyzer,
		ifaceassert.Analyzer,
		loopclosure.Analyzer,
		lostcancel.Analyzer,
		nilfunc.Analyzer,
		printf.Analyzer,
		shift.Analyzer,
		sigchanyzer.Analyzer,
		stdmethods.Analyzer,
		stringintconv.Analyzer,
		structtag.Analyzer,
		tests.Analyzer,
		testinggoroutine.Analyzer,
		timeformat.Analyzer,
		unmarshal.Analyzer,
		unreachable.Analyzer,
		unsafeptr.Analyzer,
		unusedresult.Analyzer,
	)
}


================================================
FILE: go/analysis/unitchecker/separate_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unitchecker_test

// This file illustrates separate analysis with an example.

import (
	"bytes"
	"encoding/json"
	"fmt"
	"go/token"
	"go/types"
	"io"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync/atomic"
	"testing"

	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/unitchecker"
	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// TestExampleSeparateAnalysis demonstrates the principle of separate
// analysis, the distribution of units of type-checking and analysis
// work across several processes, using serialized summaries to
// communicate between them.
//
// It uses two different kinds of task, "manager" and "worker":
//
//   - The manager computes the graph of package dependencies, and makes
//     a request to the worker for each package. It does not parse,
//     type-check, or analyze Go code. It is analogous "go vet".
//
//   - The worker, which contains the Analyzers, reads each request,
//     loads, parses, and type-checks the files of one package,
//     applies all necessary analyzers to the package, then writes
//     its results to a file. It is a unitchecker-based driver,
//     analogous to the program specified by go vet -vettool= flag.
//
// In practice these would be separate executables, but for simplicity
// of this example they are provided by one executable in two
// different modes: the Example function is the manager, and the same
// executable invoked with ENTRYPOINT=worker is the worker.
// (See TestIntegration for how this happens.)
//
// Unfortunately this can't be a true Example because of the skip,
// which requires a testing.T.
func TestExampleSeparateAnalysis(t *testing.T) {
	testenv.NeedsGoPackages(t)

	// src is an archive containing a module with a printf mistake.
	const src = `
-- go.mod --
module separate
go 1.18

-- main/main.go --
package main

import "separate/lib"

func main() {
	lib.MyPrintf("%s", 123)
}

-- lib/lib.go --
package lib

import "fmt"

func MyPrintf(format string, args ...any) {
	fmt.Printf(format, args...)
}
`

	// Expand archive into tmp tree.
	fs, err := txtar.FS(txtar.Parse([]byte(src)))
	if err != nil {
		t.Fatal(err)
	}
	tmpdir := testfiles.CopyToTmp(t, fs)

	// Load metadata for the main package and all its dependencies.
	cfg := &packages.Config{
		Mode: packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles | packages.NeedImports | packages.NeedModule,
		Dir:  tmpdir,
		Env: append(os.Environ(),
			"GOPROXY=off", // disable network
			"GOWORK=off",  // an ambient GOWORK value would break package loading
		),
		Logf: t.Logf,
	}
	pkgs, err := packages.Load(cfg, "separate/main")
	if err != nil {
		t.Fatal(err)
	}
	// Stop if any package had a metadata error.
	if packages.PrintErrors(pkgs) > 0 {
		t.Fatal("there were errors among loaded packages")
	}

	// Now we have loaded the import graph,
	// let's begin the proper work of the manager.

	// Gather root packages. They will get all analyzers,
	// whereas dependencies get only the subset that
	// produce facts or are required by them.
	roots := make(map[*packages.Package]bool)
	for _, pkg := range pkgs {
		roots[pkg] = true
	}

	// nextID generates sequence numbers for each unit of work.
	// We use it to create names of temporary files.
	var nextID atomic.Int32

	var allDiagnostics []string

	// Visit all packages in postorder: dependencies first.
	// TODO(adonovan): opt: use parallel postorder.
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		if pkg.PkgPath == "unsafe" {
			return
		}

		// Choose a unique prefix for temporary files
		// (.cfg .types .facts) produced by this package.
		// We stow it in an otherwise unused field of
		// Package so it can be accessed by our importers.
		prefix := fmt.Sprintf("%s/%d", tmpdir, nextID.Add(1))
		pkg.ExportFile = prefix

		// Construct the request to the worker.
		var (
			importMap   = make(map[string]string)
			packageFile = make(map[string]string)
			packageVetx = make(map[string]string)
		)
		for importPath, dep := range pkg.Imports {
			importMap[importPath] = dep.PkgPath
			if depPrefix := dep.ExportFile; depPrefix != "" { // skip "unsafe"
				packageFile[dep.PkgPath] = depPrefix + ".types"
				packageVetx[dep.PkgPath] = depPrefix + ".facts"
			}
		}
		cfg := unitchecker.Config{
			ID:           pkg.ID,
			ImportPath:   pkg.PkgPath,
			GoFiles:      pkg.CompiledGoFiles,
			NonGoFiles:   pkg.OtherFiles,
			IgnoredFiles: pkg.IgnoredFiles,
			ImportMap:    importMap,
			PackageFile:  packageFile,
			PackageVetx:  packageVetx,
			VetxOnly:     !roots[pkg],
			VetxOutput:   prefix + ".facts",
		}
		if pkg.Module != nil {
			if v := pkg.Module.GoVersion; v != "" {
				cfg.GoVersion = "go" + v
			}
			cfg.ModulePath = pkg.Module.Path
			cfg.ModuleVersion = pkg.Module.Version
		}

		// Write the JSON configuration message to a file.
		cfgData, err := json.Marshal(cfg)
		if err != nil {
			t.Fatalf("internal error in json.Marshal: %v", err)
		}
		cfgFile := prefix + ".cfg"
		if err := os.WriteFile(cfgFile, cfgData, 0666); err != nil {
			t.Fatal(err)
		}

		// Send the request to the worker.
		cmd := testenv.Command(t, os.Args[0], "-json", cfgFile)
		cmd.Stderr = os.Stderr
		cmd.Stdout = new(bytes.Buffer)
		cmd.Env = append(os.Environ(), "ENTRYPOINT=worker")
		if err := cmd.Run(); err != nil {
			t.Fatal(err)
		}

		// Parse JSON output and gather in allDiagnostics.
		dec := json.NewDecoder(cmd.Stdout.(io.Reader))
		for {
			type jsonDiagnostic struct {
				Posn    string `json:"posn"`
				Message string `json:"message"`
			}
			// 'results' maps Package.Path -> Analyzer.Name -> diagnostics
			var results map[string]map[string][]jsonDiagnostic
			if err := dec.Decode(&results); err != nil {
				if err == io.EOF {
					break
				}
				t.Fatalf("internal error decoding JSON: %v", err)
			}
			for _, result := range results {
				for analyzer, diags := range result {
					for _, diag := range diags {
						rel := strings.ReplaceAll(diag.Posn, tmpdir, "")
						rel = filepath.ToSlash(rel)
						msg := fmt.Sprintf("%s: [%s] %s", rel, analyzer, diag.Message)
						allDiagnostics = append(allDiagnostics, msg)
					}
				}
			}
		}
	})

	// Observe that the example produces a fact-based diagnostic
	// from separate analysis of "main", "lib", and "fmt":

	const want = `/main/main.go:6:16: [printf] separate/lib.MyPrintf format %s has arg 123 of wrong type int`
	sort.Strings(allDiagnostics)
	if got := strings.Join(allDiagnostics, "\n"); got != want {
		t.Errorf("Got: %s\nWant: %s", got, want)
	}
}

// -- worker process --

// worker is the main entry point for a unitchecker-based driver
// with only a single analyzer, for illustration.
func worker() {
	// Currently the unitchecker API doesn't allow clients to
	// control exactly how and where fact and type information
	// is produced and consumed.
	//
	// So, for example, it assumes that type information has
	// already been produced by the compiler, which is true when
	// running under "go vet", but isn't necessary. It may be more
	// convenient and efficient for a distributed analysis system
	// if the worker generates both of them, which is the approach
	// taken in this example; they could even be saved as two
	// sections of a single file.
	//
	// Consequently, this test currently needs special access to
	// private hooks in unitchecker to control how and where facts
	// and types are produced and consumed. In due course this
	// will become a respectable public API. In the meantime, it
	// should at least serve as a demonstration of how one could
	// fork unitchecker to achieve separate analysis without go vet.
	unitchecker.SetTypeImportExport(makeTypesImporter, exportTypes)

	unitchecker.Main(printf.Analyzer)
}

func makeTypesImporter(cfg *unitchecker.Config, fset *token.FileSet) types.Importer {
	imports := make(map[string]*types.Package)
	return importerFunc(func(importPath string) (*types.Package, error) {
		// Resolve import path to package path (vendoring, etc)
		path, ok := cfg.ImportMap[importPath]
		if !ok {
			return nil, fmt.Errorf("can't resolve import %q", path)
		}
		if path == "unsafe" {
			return types.Unsafe, nil
		}

		// Find, read, and decode file containing type information.
		file, ok := cfg.PackageFile[path]
		if !ok {
			return nil, fmt.Errorf("no package file for %q", path)
		}
		f, err := os.Open(file)
		if err != nil {
			return nil, err
		}
		defer f.Close() // ignore error
		return gcexportdata.Read(f, fset, imports, path)
	})
}

func exportTypes(cfg *unitchecker.Config, fset *token.FileSet, pkg *types.Package) error {
	var out bytes.Buffer
	if err := gcexportdata.Write(&out, fset, pkg); err != nil {
		return err
	}
	typesFile := strings.TrimSuffix(cfg.VetxOutput, ".facts") + ".types"
	return os.WriteFile(typesFile, out.Bytes(), 0666)
}

// -- helpers --

type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }


================================================
FILE: go/analysis/unitchecker/unitchecker.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The unitchecker package defines the main function for an analysis
// driver that analyzes a single compilation unit during a build.
// It is invoked by a build system such as "go vet":
//
//	$ go vet -vettool=$(which vet)
//
// It supports the following command-line protocol:
//
//	-V=full         describe executable               (to the build tool)
//	-flags          describe flags                    (to the build tool)
//	foo.cfg         description of compilation unit (from the build tool)
//
// This package does not depend on go/packages.
// If you need a standalone tool, use multichecker,
// which supports this mode but can also load packages
// from source using go/packages.
package unitchecker

// TODO(adonovan):
// - with gccgo, go build does not build standard library,
//   so we will not get to analyze it. Yet we must in order
//   to create base facts for, say, the fmt package for the
//   printf checker.

import (
	"archive/zip"
	"encoding/gob"
	"encoding/json"
	"flag"
	"fmt"
	"go/ast"
	"go/build"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"io"
	"log"
	"os"
	"path/filepath"
	"reflect"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/internal/analysisflags"
	"golang.org/x/tools/internal/analysis/driverutil"
	"golang.org/x/tools/internal/facts"
)

// A Config describes a compilation unit to be analyzed.
// It is provided to the tool in a JSON-encoded file
// whose name ends with ".cfg".
type Config struct {
	ID                        string // e.g. "fmt [fmt.test]"
	Compiler                  string // gc or gccgo, provided to MakeImporter
	Dir                       string // (unused)
	ImportPath                string // package path
	GoVersion                 string // minimum required Go version, such as "go1.21.0"
	GoFiles                   []string
	NonGoFiles                []string
	IgnoredFiles              []string
	ModulePath                string            // module path
	ModuleVersion             string            // module version
	ImportMap                 map[string]string // maps import path to package path
	PackageFile               map[string]string // maps package path to file of type information
	Standard                  map[string]bool   // package belongs to standard library
	PackageVetx               map[string]string // maps package path to file of fact information
	VetxOnly                  bool              // run analysis only for facts, not diagnostics
	VetxOutput                string            // where to write file of fact information
	Stdout                    string            // write stdout (e.g. JSON, unified diff) to this file
	FixArchive                string            // write fixed files to this zip archive, if non-empty
	SucceedOnTypecheckFailure bool              // obsolete awful hack; see #18395 and below
}

// Main is the main function of a vet-like analysis tool that must be
// invoked by a build system to analyze a single package.
//
// The protocol required by 'go vet -vettool=...' is that the tool must support:
//
//	-flags          describe flags in JSON
//	-V=full         describe executable for build caching
//	foo.cfg         perform separate modular analyze on the single
//	                unit described by a JSON config file foo.cfg.
//	-fix		don't print each diagnostic, apply its first fix
//	-diff		don't apply a fix, print the diff (requires -fix)
//	-json		print diagnostics and fixes in JSON form
func Main(analyzers ...*analysis.Analyzer) {
	progname := filepath.Base(os.Args[0])
	log.SetFlags(0)
	log.SetPrefix(progname + ": ")

	if err := analysis.Validate(analyzers); err != nil {
		log.Fatal(err)
	}

	flag.Usage = func() {
		fmt.Fprintf(os.Stderr, `%[1]s is a tool for static analysis of Go programs.

Usage of %[1]s:
	%.16[1]s unit.cfg	# execute analysis specified by config file
	%.16[1]s help    	# general help, including listing analyzers and flags
	%.16[1]s help name	# help on specific analyzer and its flags
`, progname)
		os.Exit(1)
	}

	analyzers = analysisflags.Parse(analyzers, true)

	args := flag.Args()
	if len(args) == 0 {
		flag.Usage()
	}
	if args[0] == "help" {
		analysisflags.Help(progname, analyzers, args[1:])
		os.Exit(0)
	}
	if len(args) != 1 || !strings.HasSuffix(args[0], ".cfg") {
		log.Fatalf(`invoking "go tool %[1]s" directly is unsupported; use "go %[1]s"`, progname)
	}
	Run(args[0], analyzers)
}

// Run reads the *.cfg file, runs the analysis,
// and calls os.Exit with an appropriate error code.
// It assumes flags have already been set.
func Run(configFile string, analyzers []*analysis.Analyzer) {
	cfg, err := readConfig(configFile)
	if err != nil {
		log.Fatal(err)
	}

	// Redirect stdout to a file as requested.
	if cfg.Stdout != "" {
		f, err := os.Create(cfg.Stdout)
		if err != nil {
			log.Fatal(err)
		}
		os.Stdout = f
	}

	fset := token.NewFileSet()
	results, err := run(fset, cfg, analyzers)
	if err != nil {
		log.Fatal(err)
	}

	code := 0

	// In VetxOnly mode, the analysis is run only for facts.
	if !cfg.VetxOnly {
		code = processResults(fset, cfg.ID, cfg.FixArchive, results)
	}

	os.Exit(code)
}

func readConfig(filename string) (*Config, error) {
	data, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	cfg := new(Config)
	if err := json.Unmarshal(data, cfg); err != nil {
		return nil, fmt.Errorf("cannot decode JSON config file %s: %v", filename, err)
	}
	if len(cfg.GoFiles) == 0 {
		// The go command disallows packages with no files.
		// The only exception is unsafe, but the go command
		// doesn't call vet on it.
		return nil, fmt.Errorf("package has no files: %s", cfg.ImportPath)
	}
	return cfg, nil
}

func processResults(fset *token.FileSet, id, fixArchive string, results []result) (exit int) {
	if analysisflags.Fix {
		// Don't print the diagnostics,
		// but apply all fixes from the root actions.

		// Convert results to form needed by ApplyFixes.
		fixActions := make([]driverutil.FixAction, len(results))
		for i, res := range results {
			fixActions[i] = driverutil.FixAction{
				Name:         res.a.Name,
				Pkg:          res.pkg,
				Files:        res.files,
				FileSet:      fset,
				ReadFileFunc: os.ReadFile, // TODO(adonovan): respect overlays
				Diagnostics:  res.diagnostics,
			}
		}

		// By default, fixes overwrite the original file.
		// With the -diff flag, print the diffs to stdout.
		// If "go fix" provides a fix archive, we write files
		// into it so that mutations happen after the build.
		write := func(filename string, content []byte) error {
			return os.WriteFile(filename, content, 0644)
		}
		if fixArchive != "" {
			f, err := os.Create(fixArchive)
			if err != nil {
				log.Fatalf("can't create -fix archive: %v", err)
			}
			zw := zip.NewWriter(f)
			zw.SetComment(id) // ignore error
			defer func() {
				if err := zw.Close(); err != nil {
					log.Fatalf("closing -fix archive zip writer: %v", err)
				}
				if err := f.Close(); err != nil {
					log.Fatalf("closing -fix archive file: %v", err)
				}
			}()
			write = func(filename string, content []byte) error {
				f, err := zw.Create(filename)
				if err != nil {
					return err
				}
				_, err = f.Write(content)
				return err
			}
		}

		if err := driverutil.ApplyFixes(fixActions, write, analysisflags.Diff, false); err != nil {
			// Fail when applying fixes failed.
			log.Print(err)
			exit = 1
		}

		// Don't proceed to print text/JSON,
		// and don't report an error
		// just because there were diagnostics.
		return
	}

	// Keep consistent with analogous logic in
	// printDiagnostics in ../internal/checker/checker.go.

	if analysisflags.JSON {
		// JSON output
		tree := make(driverutil.JSONTree)
		for _, res := range results {
			tree.Add(fset, id, res.a.Name, res.diagnostics, res.err)
		}
		tree.Print(os.Stdout) // ignore error

	} else {
		// plain text
		for _, res := range results {
			if res.err != nil {
				log.Println(res.err)
				exit = 1
			}
		}
		for _, res := range results {
			for _, diag := range res.diagnostics {
				driverutil.PrintPlain(os.Stderr, fset, analysisflags.Context, diag)
				exit = 1
			}
		}
	}

	return
}

type factImporter = func(pkgPath string) ([]byte, error)

// These four hook variables are a proof of concept of a future
// parameterization of a unitchecker API that allows the client to
// determine how and where facts and types are produced and consumed.
// (Note that the eventual API will likely be quite different.)
//
// The defaults honor a Config in a manner compatible with 'go vet'.
var (
	makeTypesImporter = func(cfg *Config, fset *token.FileSet) types.Importer {
		compilerImporter := importer.ForCompiler(fset, cfg.Compiler, func(path string) (io.ReadCloser, error) {
			// path is a resolved package path, not an import path.
			file, ok := cfg.PackageFile[path]
			if !ok {
				if cfg.Compiler == "gccgo" && cfg.Standard[path] {
					return nil, nil // fall back to default gccgo lookup
				}
				return nil, fmt.Errorf("no package file for %q", path)
			}
			return os.Open(file)
		})
		return importerFunc(func(importPath string) (*types.Package, error) {
			path, ok := cfg.ImportMap[importPath] // resolve vendoring, etc
			if !ok {
				return nil, fmt.Errorf("can't resolve import %q", path)
			}
			return compilerImporter.Import(path)
		})
	}

	exportTypes = func(*Config, *token.FileSet, *types.Package) error {
		// By default this is a no-op, because "go vet"
		// makes the compiler produce type information.
		return nil
	}

	makeFactImporter = func(cfg *Config) factImporter {
		return func(pkgPath string) ([]byte, error) {
			if vetx, ok := cfg.PackageVetx[pkgPath]; ok {
				return os.ReadFile(vetx)
			}
			return nil, nil // no .vetx file, no facts
		}
	}

	exportFacts = func(cfg *Config, data []byte) error {
		return os.WriteFile(cfg.VetxOutput, data, 0666)
	}
)

func run(fset *token.FileSet, cfg *Config, analyzers []*analysis.Analyzer) ([]result, error) {
	// Load, parse, typecheck.
	var files []*ast.File
	for _, name := range cfg.GoFiles {
		f, err := parser.ParseFile(fset, name, nil, parser.ParseComments)
		if err != nil {
			if cfg.SucceedOnTypecheckFailure {
				// Silently succeed; let the compiler
				// report parse errors.
				err = nil
			}
			return nil, err
		}
		files = append(files, f)
	}
	tc := &types.Config{
		Importer:  makeTypesImporter(cfg, fset),
		Sizes:     types.SizesFor("gc", build.Default.GOARCH), // TODO(adonovan): use cfg.Compiler
		GoVersion: cfg.GoVersion,
	}
	info := &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Instances:    make(map[*ast.Ident]types.Instance),
		Scopes:       make(map[ast.Node]*types.Scope),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		FileVersions: make(map[*ast.File]string),
	}

	pkg, err := tc.Check(cfg.ImportPath, fset, files, info)
	if err != nil {
		if cfg.SucceedOnTypecheckFailure {
			// Silently succeed; let the compiler
			// report type errors.
			err = nil
		}
		return nil, err
	}

	// Register fact types with gob.
	// In VetxOnly mode, analyzers are only for their facts,
	// so we can skip any analysis that neither produces facts
	// nor depends on any analysis that produces facts.
	//
	// TODO(adonovan): fix: the command (and logic!) here are backwards.
	// It should say "...nor is required by any...". (Issue 443099)
	//
	// Also build a map to hold working state and result.
	type action struct {
		once        sync.Once
		result      any
		err         error
		usesFacts   bool // (transitively uses)
		diagnostics []analysis.Diagnostic
	}
	actions := make(map[*analysis.Analyzer]*action)
	var registerFacts func(a *analysis.Analyzer) bool
	registerFacts = func(a *analysis.Analyzer) bool {
		act, ok := actions[a]
		if !ok {
			act = new(action)
			var usesFacts bool
			for _, f := range a.FactTypes {
				usesFacts = true
				gob.Register(f)
			}
			for _, req := range a.Requires {
				if registerFacts(req) {
					usesFacts = true
				}
			}
			act.usesFacts = usesFacts
			actions[a] = act
		}
		return act.usesFacts
	}
	var filtered []*analysis.Analyzer
	for _, a := range analyzers {
		if registerFacts(a) || !cfg.VetxOnly {
			filtered = append(filtered, a)
		}
	}
	analyzers = filtered

	// Read facts from imported packages.
	facts, err := facts.NewDecoder(pkg).Decode(makeFactImporter(cfg))
	if err != nil {
		return nil, err
	}

	// In parallel, execute the DAG of analyzers.
	var exec func(a *analysis.Analyzer) *action
	var execAll func(analyzers []*analysis.Analyzer)
	exec = func(a *analysis.Analyzer) *action {
		act := actions[a]
		act.once.Do(func() {
			execAll(a.Requires) // prefetch dependencies in parallel

			// The inputs to this analysis are the
			// results of its prerequisites.
			inputs := make(map[*analysis.Analyzer]any)
			var failed []string
			for _, req := range a.Requires {
				reqact := exec(req)
				if reqact.err != nil {
					failed = append(failed, req.String())
					continue
				}
				inputs[req] = reqact.result
			}

			// Report an error if any dependency failed.
			if failed != nil {
				sort.Strings(failed)
				act.err = fmt.Errorf("failed prerequisites: %s", strings.Join(failed, ", "))
				return
			}

			factFilter := make(map[reflect.Type]bool)
			for _, f := range a.FactTypes {
				factFilter[reflect.TypeOf(f)] = true
			}

			module := &analysis.Module{
				Path:      cfg.ModulePath,
				Version:   cfg.ModuleVersion,
				GoVersion: cfg.GoVersion,
			}

			pass := &analysis.Pass{
				Analyzer:     a,
				Fset:         fset,
				Files:        files,
				OtherFiles:   cfg.NonGoFiles,
				IgnoredFiles: cfg.IgnoredFiles,
				Pkg:          pkg,
				TypesInfo:    info,
				TypesSizes:   tc.Sizes,
				TypeErrors:   nil, // unitchecker doesn't RunDespiteErrors
				ResultOf:     inputs,
				Report: func(d analysis.Diagnostic) {
					// Unitchecker doesn't apply fixes, but it does report them in the JSON output.
					if err := driverutil.ValidateFixes(fset, a, d.SuggestedFixes); err != nil {
						// Since we have diagnostics, the exit code will be nonzero,
						// so logging these errors is sufficient.
						log.Println(err)
						d.SuggestedFixes = nil
					}
					act.diagnostics = append(act.diagnostics, d)
				},
				ImportObjectFact:  facts.ImportObjectFact,
				ExportObjectFact:  facts.ExportObjectFact,
				AllObjectFacts:    func() []analysis.ObjectFact { return facts.AllObjectFacts(factFilter) },
				ImportPackageFact: facts.ImportPackageFact,
				ExportPackageFact: facts.ExportPackageFact,
				AllPackageFacts:   func() []analysis.PackageFact { return facts.AllPackageFacts(factFilter) },
				Module:            module,
			}
			pass.ReadFile = driverutil.CheckedReadFile(pass, os.ReadFile)

			t0 := time.Now()
			act.result, act.err = a.Run(pass)

			if act.err == nil { // resolve URLs on diagnostics.
				for i := range act.diagnostics {
					if url, uerr := driverutil.ResolveURL(a, act.diagnostics[i]); uerr == nil {
						act.diagnostics[i].URL = url
					} else {
						act.err = uerr // keep the last error
					}
				}
			}
			if false {
				log.Printf("analysis %s = %s", pass, time.Since(t0))
			}
		})
		return act
	}
	execAll = func(analyzers []*analysis.Analyzer) {
		var wg sync.WaitGroup
		for _, a := range analyzers {
			wg.Add(1)
			go func(a *analysis.Analyzer) {
				_ = exec(a)
				wg.Done()
			}(a)
		}
		wg.Wait()
	}

	execAll(analyzers)

	// Return diagnostics and errors from root analyzers.
	results := make([]result, len(analyzers))
	for i, a := range analyzers {
		act := actions[a]
		results[i] = result{pkg, files, a, act.diagnostics, act.err}
	}

	data := facts.Encode()
	if err := exportFacts(cfg, data); err != nil {
		return nil, fmt.Errorf("failed to export analysis facts: %v", err)
	}
	if err := exportTypes(cfg, fset, pkg); err != nil {
		return nil, fmt.Errorf("failed to export type information: %v", err)
	}

	return results, nil
}

type result struct {
	pkg         *types.Package
	files       []*ast.File
	a           *analysis.Analyzer
	diagnostics []analysis.Diagnostic
	err         error
}

type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }


================================================
FILE: go/analysis/unitchecker/unitchecker_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unitchecker_test

import (
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis/passes/assign"
	"golang.org/x/tools/go/analysis/passes/findcall"
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/unitchecker"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestMain(m *testing.M) {
	// child process?
	switch os.Getenv("ENTRYPOINT") {
	case "vet":
		vet()
		panic("unreachable")
	case "minivet":
		minivet()
		panic("unreachable")
	case "worker":
		worker() // see ExampleSeparateAnalysis
		panic("unreachable")
	}

	// test process
	flag.Parse()
	os.Exit(m.Run())
}

// minivet is a vet-like tool with a few analyzers, for testing.
func minivet() {
	unitchecker.Main(
		findcall.Analyzer,
		printf.Analyzer,
		assign.Analyzer,
	)
}

// This is a very basic integration test of modular
// analysis with facts using unitchecker under "go vet".
// It fork/execs the main function above.
func TestIntegration(t *testing.T) {
	if runtime.GOOS != "linux" && runtime.GOOS != "darwin" {
		t.Skipf("skipping fork/exec test on this platform")
	}

	const src = `
-- go.mod --
module golang.org/fake
go 1.24

-- a/a.go --
package a

func _() {
	MyFunc123()
}

func MyFunc123() {}

-- b/b.go --
package b

import "golang.org/fake/a"

func _() {
	a.MyFunc123()
	MyFunc123()
}

func MyFunc123() {}

-- c/c.go --
package c

func _() {
    i := 5
    i = i
}

-- d/d.go --
package d

import "fmt"

var (
	msg string
	_ = fmt.Sprintf(msg)
)

-- d/dgen.go --
// Code generated by hand. DO NOT EDIT.

package d

import "fmt"

var _ = fmt.Sprintf(msg)
`
	// Expand archive into tmp tree.
	fs, err := txtar.FS(txtar.Parse([]byte(src)))
	if err != nil {
		t.Fatal(err)
	}
	tmpdir := testfiles.CopyToTmp(t, fs)

	// -- operators --

	// vet runs "go vet" with the specified arguments (plus -findcall.name=MyFunc123).
	vet := func(t *testing.T, args ...string) (exitcode int, stdout, stderr string) {
		cmd := exec.Command("go", "vet", "-vettool="+os.Args[0], "-findcall.name=MyFunc123")
		cmd.Stdout = new(strings.Builder)
		cmd.Stderr = new(strings.Builder)
		cmd.Args = append(cmd.Args, args...)
		cmd.Env = append(os.Environ(), "ENTRYPOINT=minivet")
		cmd.Dir = tmpdir
		if err := cmd.Run(); err != nil {
			exitErr, ok := err.(*exec.ExitError)
			if !ok {
				t.Fatalf("couldn't exec %v: %v", cmd, err)
			}
			exitcode = exitErr.ExitCode()
		}

		// Sanitize filenames; this is imperfect due to
		// (e.g.) /private/tmp -> /tmp symlink on macOS.
		stdout = strings.ReplaceAll(fmt.Sprint(cmd.Stdout), tmpdir, "TMPDIR")
		stderr = strings.ReplaceAll(fmt.Sprint(cmd.Stderr), tmpdir, "TMPDIR")

		// Show vet information on failure.
		t.Cleanup(func() {
			if t.Failed() {
				t.Logf("command: %v", cmd)
				t.Logf("exit code: %d", exitcode)
				t.Logf("stdout: %s", stdout)
				t.Logf("stderr: %s", stderr)
			}
		})
		return
	}

	// exitcode asserts that the exit code was "want".
	exitcode := func(t *testing.T, got, want int) {
		if got != want {
			t.Fatalf("vet tool exit code was %d", got)
		}
	}

	// parseJSON parses the JSON diagnostics into a simple line-oriented form.
	parseJSON := func(t *testing.T, stdout string) string {
		var v map[string]map[string][]map[string]any
		if err := json.Unmarshal([]byte(stdout), &v); err != nil {
			t.Fatalf("invalid JSON: %v", err)
		}
		var res strings.Builder
		for pkgpath, v := range v {
			for analyzer, v := range v {
				for _, v := range v {
					fmt.Fprintf(&res, "%s: [%s@%s] %v\n",
						v["posn"],
						analyzer, pkgpath,
						v["message"])
				}
			}
		}
		// Show parsed JSON information on failure.
		t.Cleanup(func() {
			if t.Failed() {
				t.Logf("json: %s", &res)
			}
		})
		return res.String()
	}

	// substring asserts that the labeled output contained the substring.
	substring := func(t *testing.T, label, output, substr string) {
		if !strings.Contains(output, substr) {
			t.Fatalf("%s: expected substring %q", label, substr)
		}
	}

	// contains asserts that the specified file contains the substring.
	contains := func(t *testing.T, filename, substr string) {
		content, err := os.ReadFile(filepath.Join(tmpdir, filename))
		if err != nil {
			t.Fatalf("can't read %s: %v", filename, err)
		}
		t.Cleanup(func() {
			if t.Failed() {
				t.Logf("content of %s: <<%s>>", filename, content)
			}
		})
		substring(t, filename, string(content), substr)
	}

	// -- scenarios --

	t.Run("a", func(t *testing.T) {
		code, _, stderr := vet(t, "golang.org/fake/a")
		exitcode(t, code, 1)
		substring(t, "stderr", stderr, "a/a.go:4:11: call of MyFunc123")
	})
	t.Run("b", func(t *testing.T) {
		code, _, stderr := vet(t, "golang.org/fake/b")
		exitcode(t, code, 1)
		substring(t, "stderr", stderr, "b/b.go:6:13: call of MyFunc123")
		substring(t, "stderr", stderr, "b/b.go:7:11: call of MyFunc123")
	})
	t.Run("c", func(t *testing.T) {
		code, _, stderr := vet(t, "golang.org/fake/c")
		exitcode(t, code, 1)
		substring(t, "stderr", stderr, "c/c.go:5:5: self-assignment of i")
	})
	t.Run("ab", func(t *testing.T) {
		code, _, stderr := vet(t, "golang.org/fake/a", "golang.org/fake/b")
		exitcode(t, code, 1)
		substring(t, "stderr", stderr, "a/a.go:4:11: call of MyFunc123")
		substring(t, "stderr", stderr, "b/b.go:6:13: call of MyFunc123")
		substring(t, "stderr", stderr, "b/b.go:7:11: call of MyFunc123")
	})
	t.Run("a-json", func(t *testing.T) {
		code, stdout, _ := vet(t, "-json", "golang.org/fake/a")
		exitcode(t, code, 0)
		testenv.NeedsGo1Point(t, 26) // depends on CL 702815 (go vet -json => stdout)
		json := parseJSON(t, stdout)
		substring(t, "json", json, "a/a.go:4:11: [findcall@golang.org/fake/a] call of MyFunc123")
	})
	t.Run("c-json", func(t *testing.T) {
		code, stdout, _ := vet(t, "-json", "golang.org/fake/c")
		exitcode(t, code, 0)
		testenv.NeedsGo1Point(t, 26) // depends on CL 702815 (go vet -json => stdout)
		json := parseJSON(t, stdout)
		substring(t, "json", json, "c/c.go:5:5: [assign@golang.org/fake/c] self-assignment of i")
	})
	t.Run("a-context", func(t *testing.T) {
		code, _, stderr := vet(t, "-c=0", "golang.org/fake/a")
		exitcode(t, code, 1)
		substring(t, "stderr", stderr, "a/a.go:4:11: call of MyFunc123")
		substring(t, "stderr", stderr, "4		MyFunc123")
	})
	t.Run("d-fix", func(t *testing.T) {
		testenv.NeedsGo1Point(t, 26)
		code, _, stderr := vet(t, "-fix", "-v", "golang.org/fake/d")
		exitcode(t, code, 0)
		contains(t, "d/d.go", `fmt.Sprintf("%s", msg)`) // fixed
		contains(t, "d/dgen.go", `fmt.Sprintf(msg)`)    // fix not applied to generated file
		// TODO(adonovan): plumb -v from go vet/fix down to unitchecker.
		if false {
			substring(t, "stderr", stderr, "skipped 1 fix that would edit generated files")
			substring(t, "stderr", stderr, "applied 1 of 2 fixes; 1 files updated")
		}
	})
}


================================================
FILE: go/analysis/unitchecker/vet_std_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unitchecker_test

import (
	"go/version"
	"os"
	"os/exec"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis/passes/appends"
	"golang.org/x/tools/go/analysis/passes/asmdecl"
	"golang.org/x/tools/go/analysis/passes/assign"
	"golang.org/x/tools/go/analysis/passes/atomic"
	"golang.org/x/tools/go/analysis/passes/bools"
	"golang.org/x/tools/go/analysis/passes/buildtag"
	"golang.org/x/tools/go/analysis/passes/cgocall"
	"golang.org/x/tools/go/analysis/passes/composite"
	"golang.org/x/tools/go/analysis/passes/copylock"
	"golang.org/x/tools/go/analysis/passes/defers"
	"golang.org/x/tools/go/analysis/passes/directive"
	"golang.org/x/tools/go/analysis/passes/errorsas"
	"golang.org/x/tools/go/analysis/passes/framepointer"
	"golang.org/x/tools/go/analysis/passes/gofix"
	"golang.org/x/tools/go/analysis/passes/hostport"
	"golang.org/x/tools/go/analysis/passes/httpresponse"
	"golang.org/x/tools/go/analysis/passes/ifaceassert"
	"golang.org/x/tools/go/analysis/passes/loopclosure"
	"golang.org/x/tools/go/analysis/passes/lostcancel"
	"golang.org/x/tools/go/analysis/passes/nilfunc"
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/passes/shift"
	"golang.org/x/tools/go/analysis/passes/sigchanyzer"
	"golang.org/x/tools/go/analysis/passes/stdmethods"
	"golang.org/x/tools/go/analysis/passes/stdversion"
	"golang.org/x/tools/go/analysis/passes/stringintconv"
	"golang.org/x/tools/go/analysis/passes/structtag"
	"golang.org/x/tools/go/analysis/passes/testinggoroutine"
	"golang.org/x/tools/go/analysis/passes/tests"
	"golang.org/x/tools/go/analysis/passes/timeformat"
	"golang.org/x/tools/go/analysis/passes/unmarshal"
	"golang.org/x/tools/go/analysis/passes/unreachable"
	"golang.org/x/tools/go/analysis/passes/unusedresult"
	"golang.org/x/tools/go/analysis/unitchecker"
)

// vet is the entrypoint of this executable when ENTRYPOINT=vet.
// Keep consistent with the actual vet in GOROOT/src/cmd/vet/main.go.
func vet() {
	unitchecker.Main(
		appends.Analyzer,
		asmdecl.Analyzer,
		assign.Analyzer,
		atomic.Analyzer,
		bools.Analyzer,
		buildtag.Analyzer,
		cgocall.Analyzer,
		composite.Analyzer,
		copylock.Analyzer,
		defers.Analyzer,
		directive.Analyzer,
		errorsas.Analyzer,
		framepointer.Analyzer,
		gofix.Analyzer,
		httpresponse.Analyzer,
		hostport.Analyzer,
		ifaceassert.Analyzer,
		loopclosure.Analyzer,
		lostcancel.Analyzer,
		nilfunc.Analyzer,
		printf.Analyzer,
		shift.Analyzer,
		sigchanyzer.Analyzer,
		stdmethods.Analyzer,
		stdversion.Analyzer,
		stringintconv.Analyzer,
		structtag.Analyzer,
		testinggoroutine.Analyzer,
		tests.Analyzer,
		timeformat.Analyzer,
		unmarshal.Analyzer,
		unreachable.Analyzer,
		// unsafeptr.Analyzer, // currently reports findings in runtime
		unusedresult.Analyzer,
	)
}

// TestVetStdlib runs the same analyzers as the actual vet over the
// standard library, using go vet and unitchecker, to ensure that
// there are no findings.
func TestVetStdlib(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in -short mode")
	}
	if builder := os.Getenv("GO_BUILDER_NAME"); builder != "" && !strings.HasPrefix(builder, "x_tools-gotip-") {
		// Run on builders like x_tools-gotip-linux-amd64-longtest,
		// skip on others like x_tools-go1.24-linux-amd64-longtest.
		t.Skipf("This test is only wanted on development branches where code can be easily fixed. Skipping on non-gotip builder %q.", builder)
	} else if v := runtime.Version(); !strings.Contains(v, "devel") || version.Compare(v, version.Lang(v)) != 0 {
		// Run on versions like "go1.25-devel_9ce47e66e8 Wed Mar 26 03:48:50 2025 -0700",
		// skip on others like "go1.24.2" or "go1.24.2-devel_[…]".
		t.Skipf("This test is only wanted on development versions where code can be easily fixed. Skipping on non-gotip version %q.", v)
	}

	cmd := exec.Command("go", "vet", "-vettool="+os.Args[0], "std")
	cmd.Env = append(os.Environ(), "ENTRYPOINT=vet")
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Errorf("go vet std failed (%v):\n%s", err, out)
	}
}


================================================
FILE: go/analysis/validate.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysis

import (
	"fmt"
	"reflect"
	"strings"
	"unicode"
)

// Validate reports an error if any of the analyzers are misconfigured.
// Checks include:
// that the name is a valid identifier;
// that the Doc is not empty;
// that the Run is non-nil;
// that the Requires graph is acyclic;
// that analyzer fact types are unique;
// that each fact type is a pointer.
//
// Analyzer names need not be unique, though this may be confusing.
func Validate(analyzers []*Analyzer) error {
	// Map each fact type to its sole generating analyzer.
	factTypes := make(map[reflect.Type]*Analyzer)

	// Traverse the Requires graph, depth first.
	const (
		white = iota
		grey
		black
		finished
	)
	color := make(map[*Analyzer]uint8)
	var visit func(a *Analyzer) error
	visit = func(a *Analyzer) error {
		if a == nil {
			return fmt.Errorf("nil *Analyzer")
		}
		if color[a] == white {
			color[a] = grey

			// names
			if !validIdent(a.Name) {
				return fmt.Errorf("invalid analyzer name %q", a)
			}

			if a.Doc == "" {
				return fmt.Errorf("analyzer %q is undocumented", a)
			}

			if a.Run == nil {
				return fmt.Errorf("analyzer %q has nil Run", a)
			}
			// fact types
			for _, f := range a.FactTypes {
				if f == nil {
					return fmt.Errorf("analyzer %s has nil FactType", a)
				}
				t := reflect.TypeOf(f)
				if prev := factTypes[t]; prev != nil {
					return fmt.Errorf("fact type %s registered by two analyzers: %v, %v",
						t, a, prev)
				}
				if t.Kind() != reflect.Pointer {
					return fmt.Errorf("%s: fact type %s is not a pointer", a, t)
				}
				factTypes[t] = a
			}

			// recursion
			for _, req := range a.Requires {
				if err := visit(req); err != nil {
					return err
				}
			}
			color[a] = black
		}

		if color[a] == grey {
			stack := []*Analyzer{a}
			inCycle := map[string]bool{}
			for len(stack) > 0 {
				current := stack[len(stack)-1]
				stack = stack[:len(stack)-1]
				if color[current] == grey && !inCycle[current.Name] {
					inCycle[current.Name] = true
					stack = append(stack, current.Requires...)
				}
			}
			return &CycleInRequiresGraphError{AnalyzerNames: inCycle}
		}

		return nil
	}
	for _, a := range analyzers {
		if err := visit(a); err != nil {
			return err
		}
	}

	// Reject duplicates among analyzers.
	// Precondition:  color[a] == black.
	// Postcondition: color[a] == finished.
	for _, a := range analyzers {
		if color[a] == finished {
			return fmt.Errorf("duplicate analyzer: %s", a.Name)
		}
		color[a] = finished
	}

	return nil
}

func validIdent(name string) bool {
	for i, r := range name {
		if !(r == '_' || unicode.IsLetter(r) || i > 0 && unicode.IsDigit(r)) {
			return false
		}
	}
	return name != ""
}

type CycleInRequiresGraphError struct {
	AnalyzerNames map[string]bool
}

func (e *CycleInRequiresGraphError) Error() string {
	var b strings.Builder
	b.WriteString("cycle detected involving the following analyzers:")
	for n := range e.AnalyzerNames {
		b.WriteByte(' ')
		b.WriteString(n)
	}
	return b.String()
}


================================================
FILE: go/analysis/validate_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analysis

import (
	"strings"
	"testing"
)

func TestValidate(t *testing.T) {
	var (
		run = func(p *Pass) (any, error) {
			return nil, nil
		}
		dependsOnSelf = &Analyzer{
			Name: "dependsOnSelf",
			Doc:  "this analyzer depends on itself",
			Run:  run,
		}
		inCycleA = &Analyzer{
			Name: "inCycleA",
			Doc:  "this analyzer depends on inCycleB",
			Run:  run,
		}
		inCycleB = &Analyzer{
			Name: "inCycleB",
			Doc:  "this analyzer depends on inCycleA and notInCycleA",
			Run:  run,
		}
		pointsToCycle = &Analyzer{
			Name: "pointsToCycle",
			Doc:  "this analyzer depends on inCycleA",
			Run:  run,
		}
		notInCycleA = &Analyzer{
			Name: "notInCycleA",
			Doc:  "this analyzer depends on notInCycleB and notInCycleC",
			Run:  run,
		}
		notInCycleB = &Analyzer{
			Name: "notInCycleB",
			Doc:  "this analyzer depends on notInCycleC",
			Run:  run,
		}
		notInCycleC = &Analyzer{
			Name: "notInCycleC",
			Doc:  "this analyzer has no dependencies",
			Run:  run,
		}
	)

	dependsOnSelf.Requires = append(dependsOnSelf.Requires, dependsOnSelf)
	inCycleA.Requires = append(inCycleA.Requires, inCycleB)
	inCycleB.Requires = append(inCycleB.Requires, inCycleA, notInCycleA)
	pointsToCycle.Requires = append(pointsToCycle.Requires, inCycleA)
	notInCycleA.Requires = append(notInCycleA.Requires, notInCycleB, notInCycleC)
	notInCycleB.Requires = append(notInCycleB.Requires, notInCycleC)
	notInCycleC.Requires = []*Analyzer{}

	cases := []struct {
		analyzers        []*Analyzer
		wantErr          bool
		analyzersInCycle map[string]bool
	}{
		{
			[]*Analyzer{dependsOnSelf},
			true,
			map[string]bool{"dependsOnSelf": true},
		},
		{
			[]*Analyzer{inCycleA, inCycleB},
			true,
			map[string]bool{"inCycleA": true, "inCycleB": true},
		},
		{
			[]*Analyzer{pointsToCycle},
			true,
			map[string]bool{"inCycleA": true, "inCycleB": true},
		},
		{
			[]*Analyzer{notInCycleA},
			false,
			map[string]bool{},
		},
	}

	for _, c := range cases {
		got := Validate(c.analyzers)

		if !c.wantErr {
			if got == nil {
				continue
			}
			t.Errorf("got unexpected error while validating analyzers %v: %v", c.analyzers, got)
		}

		if got == nil {
			t.Errorf("expected error while validating analyzers %v, but got nil", c.analyzers)
		}

		err, ok := got.(*CycleInRequiresGraphError)
		if !ok {
			t.Errorf("want CycleInRequiresGraphError, got %T", err)
		}

		for a := range c.analyzersInCycle {
			if !err.AnalyzerNames[a] {
				t.Errorf("analyzer %s should be in cycle", a)
			}
		}
		for a := range err.AnalyzerNames {
			if !c.analyzersInCycle[a] {
				t.Errorf("analyzer %s should not be in cycle", a)
			}
		}
	}
}

func TestCycleInRequiresGraphErrorMessage(t *testing.T) {
	err := CycleInRequiresGraphError{}
	errMsg := err.Error()
	wantSubstring := "cycle detected"
	if !strings.Contains(errMsg, wantSubstring) {
		t.Errorf("error string %s does not contain expected substring %q", errMsg, wantSubstring)
	}
}

func TestValidateEmptyDoc(t *testing.T) {
	withoutDoc := &Analyzer{
		Name: "withoutDoc",
		Run: func(p *Pass) (any, error) {
			return nil, nil
		},
	}
	err := Validate([]*Analyzer{withoutDoc})
	if err == nil || !strings.Contains(err.Error(), "is undocumented") {
		t.Errorf("got unexpected error while validating analyzers withoutDoc: %v", err)
	}
}

func TestValidateNoRun(t *testing.T) {
	withoutRun := &Analyzer{
		Name: "withoutRun",
		Doc:  "this analyzer has no Run",
	}
	err := Validate([]*Analyzer{withoutRun})
	if err == nil || !strings.Contains(err.Error(), "has nil Run") {
		t.Errorf("got unexpected error while validating analyzers withoutRun: %v", err)
	}
}


================================================
FILE: go/ast/astutil/enclosing.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

// This file defines utilities for working with source positions.

import (
	"fmt"
	"go/ast"
	"go/token"
	"sort"
)

// PathEnclosingInterval returns the node that encloses the source
// interval [start, end), and all its ancestors up to the AST root.
//
// The definition of "enclosing" used by this function considers
// additional whitespace abutting a node to be enclosed by it.
// In this example:
//
//	z := x + y // add them
//	     <-A->
//	    <----B----->
//
// the ast.BinaryExpr(+) node is considered to enclose interval B
// even though its [Pos()..End()) is actually only interval A.
// This behaviour makes user interfaces more tolerant of imperfect
// input.
//
// This function treats tokens as nodes, though they are not included
// in the result. e.g. PathEnclosingInterval("+") returns the
// enclosing ast.BinaryExpr("x + y").
//
// If start==end, the 1-char interval following start is used instead.
//
// The 'exact' result is true if the interval contains only path[0]
// and perhaps some adjacent whitespace.  It is false if the interval
// overlaps multiple children of path[0], or if it contains only
// interior whitespace of path[0].
// In this example:
//
//	z := x + y // add them
//	  <--C-->     <---E-->
//	    ^
//	    D
//
// intervals C, D and E are inexact.  C is contained by the
// z-assignment statement, because it spans three of its children (:=,
// x, +).  So too is the 1-char interval D, because it contains only
// interior whitespace of the assignment.  E is considered interior
// whitespace of the BlockStmt containing the assignment.
//
// The resulting path is never empty; it always contains at least the
// 'root' *ast.File.  Ideally PathEnclosingInterval would reject
// intervals that lie wholly or partially outside the range of the
// file, but unfortunately ast.File records only the token.Pos of
// the 'package' keyword, but not of the start of the file itself.
func PathEnclosingInterval(root *ast.File, start, end token.Pos) (path []ast.Node, exact bool) {
	// fmt.Printf("EnclosingInterval %d %d\n", start, end) // debugging

	// Precondition: node.[Pos..End) and adjoining whitespace contain [start, end).
	var visit func(node ast.Node) bool
	visit = func(node ast.Node) bool {
		path = append(path, node)

		nodePos := node.Pos()
		nodeEnd := node.End()

		// fmt.Printf("visit(%T, %d, %d)\n", node, nodePos, nodeEnd) // debugging

		// Intersect [start, end) with interval of node.
		if start < nodePos {
			start = nodePos
		}
		if end > nodeEnd {
			end = nodeEnd
		}

		// Find sole child that contains [start, end).
		children := childrenOf(node)
		l := len(children)
		for i, child := range children {
			// [childPos, childEnd) is unaugmented interval of child.
			childPos := child.Pos()
			childEnd := child.End()

			// [augPos, augEnd) is whitespace-augmented interval of child.
			augPos := childPos
			augEnd := childEnd
			if i > 0 {
				augPos = children[i-1].End() // start of preceding whitespace
			}
			if i < l-1 {
				nextChildPos := children[i+1].Pos()
				// Does [start, end) lie between child and next child?
				if start >= augEnd && end <= nextChildPos {
					return false // inexact match
				}
				augEnd = nextChildPos // end of following whitespace
			}

			// fmt.Printf("\tchild %d: [%d..%d)\tcontains interval [%d..%d)?\n",
			// 	i, augPos, augEnd, start, end) // debugging

			// Does augmented child strictly contain [start, end)?
			if augPos <= start && end <= augEnd {
				if is[tokenNode](child) {
					return true
				}

				// childrenOf elides the FuncType node beneath FuncDecl.
				// Add it back here for TypeParams, Params, Results,
				// all FieldLists). But we don't add it back for the "func" token
				// even though it is the tree at FuncDecl.Type.Func.
				if decl, ok := node.(*ast.FuncDecl); ok {
					if fields, ok := child.(*ast.FieldList); ok && fields != decl.Recv {
						path = append(path, decl.Type)
					}
				}

				return visit(child)
			}

			// Does [start, end) overlap multiple children?
			// i.e. left-augmented child contains start
			// but LR-augmented child does not contain end.
			if start < childEnd && end > augEnd {
				break
			}
		}

		// No single child contained [start, end),
		// so node is the result.  Is it exact?

		// (It's tempting to put this condition before the
		// child loop, but it gives the wrong result in the
		// case where a node (e.g. ExprStmt) and its sole
		// child have equal intervals.)
		if start == nodePos && end == nodeEnd {
			return true // exact match
		}

		return false // inexact: overlaps multiple children
	}

	// Ensure [start,end) is nondecreasing.
	if start > end {
		start, end = end, start
	}

	if start < root.End() && end > root.Pos() {
		if start == end {
			end = start + 1 // empty interval => interval of size 1
		}
		exact = visit(root)

		// Reverse the path:
		for i, l := 0, len(path); i < l/2; i++ {
			path[i], path[l-1-i] = path[l-1-i], path[i]
		}
	} else {
		// Selection lies within whitespace preceding the
		// first (or following the last) declaration in the file.
		// The result nonetheless always includes the ast.File.
		path = append(path, root)
	}

	return
}

// tokenNode is a dummy implementation of ast.Node for a single token.
// They are used transiently by PathEnclosingInterval but never escape
// this package.
type tokenNode struct {
	pos token.Pos
	end token.Pos
}

func (n tokenNode) Pos() token.Pos {
	return n.pos
}

func (n tokenNode) End() token.Pos {
	return n.end
}

func tok(pos token.Pos, len int) ast.Node {
	return tokenNode{pos, pos + token.Pos(len)}
}

// childrenOf returns the direct non-nil children of ast.Node n.
// It may include fake ast.Node implementations for bare tokens.
// it is not safe to call (e.g.) ast.Walk on such nodes.
func childrenOf(n ast.Node) []ast.Node {
	var children []ast.Node

	// First add nodes for all true subtrees.
	ast.Inspect(n, func(node ast.Node) bool {
		if node == n { // push n
			return true // recur
		}
		if node != nil { // push child
			children = append(children, node)
		}
		return false // no recursion
	})

	// TODO(adonovan): be more careful about missing (!Pos.Valid)
	// tokens in trees produced from invalid input.

	// Then add fake Nodes for bare tokens.
	switch n := n.(type) {
	case *ast.ArrayType:
		children = append(children,
			tok(n.Lbrack, len("[")),
			tok(n.Elt.End(), len("]")))

	case *ast.AssignStmt:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.BasicLit:
		children = append(children,
			tok(n.ValuePos, len(n.Value)))

	case *ast.BinaryExpr:
		children = append(children, tok(n.OpPos, len(n.Op.String())))

	case *ast.BlockStmt:
		if n.Lbrace.IsValid() {
			children = append(children, tok(n.Lbrace, len("{")))
		}
		if n.Rbrace.IsValid() {
			children = append(children, tok(n.Rbrace, len("}")))
		}

	case *ast.BranchStmt:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.CallExpr:
		children = append(children,
			tok(n.Lparen, len("(")),
			tok(n.Rparen, len(")")))
		if n.Ellipsis != 0 {
			children = append(children, tok(n.Ellipsis, len("...")))
		}

	case *ast.CaseClause:
		if n.List == nil {
			children = append(children,
				tok(n.Case, len("default")))
		} else {
			children = append(children,
				tok(n.Case, len("case")))
		}
		children = append(children, tok(n.Colon, len(":")))

	case *ast.ChanType:
		switch n.Dir {
		case ast.RECV:
			children = append(children, tok(n.Begin, len("<-chan")))
		case ast.SEND:
			children = append(children, tok(n.Begin, len("chan<-")))
		case ast.RECV | ast.SEND:
			children = append(children, tok(n.Begin, len("chan")))
		}

	case *ast.CommClause:
		if n.Comm == nil {
			children = append(children,
				tok(n.Case, len("default")))
		} else {
			children = append(children,
				tok(n.Case, len("case")))
		}
		children = append(children, tok(n.Colon, len(":")))

	case *ast.Comment:
		// nop

	case *ast.CommentGroup:
		// nop

	case *ast.CompositeLit:
		children = append(children,
			tok(n.Lbrace, len("{")),
			tok(n.Rbrace, len("{")))

	case *ast.DeclStmt:
		// nop

	case *ast.DeferStmt:
		children = append(children,
			tok(n.Defer, len("defer")))

	case *ast.Ellipsis:
		children = append(children,
			tok(n.Ellipsis, len("...")))

	case *ast.EmptyStmt:
		// nop

	case *ast.ExprStmt:
		// nop

	case *ast.Field:
		// TODO(adonovan): Field.{Doc,Comment,Tag}?

	case *ast.FieldList:
		if n.Opening.IsValid() {
			children = append(children, tok(n.Opening, len("(")))
		}
		if n.Closing.IsValid() {
			children = append(children, tok(n.Closing, len(")")))
		}

	case *ast.File:
		// TODO test: Doc
		children = append(children,
			tok(n.Package, len("package")))

	case *ast.ForStmt:
		children = append(children,
			tok(n.For, len("for")))

	case *ast.FuncDecl:
		// TODO(adonovan): FuncDecl.Comment?

		// Uniquely, FuncDecl breaks the invariant that
		// preorder traversal yields tokens in lexical order:
		// in fact, FuncDecl.Recv precedes FuncDecl.Type.Func.
		//
		// As a workaround, we inline the case for FuncType
		// here and order things correctly.
		// We also need to insert the elided FuncType just
		// before the 'visit' recursion.
		//
		children = nil // discard ast.Walk(FuncDecl) info subtrees
		children = append(children, tok(n.Type.Func, len("func")))
		if n.Recv != nil {
			children = append(children, n.Recv)
		}
		children = append(children, n.Name)
		if tparams := n.Type.TypeParams; tparams != nil {
			children = append(children, tparams)
		}
		if n.Type.Params != nil {
			children = append(children, n.Type.Params)
		}
		if n.Type.Results != nil {
			children = append(children, n.Type.Results)
		}
		if n.Body != nil {
			children = append(children, n.Body)
		}

	case *ast.FuncLit:
		// nop

	case *ast.FuncType:
		if n.Func != 0 {
			children = append(children,
				tok(n.Func, len("func")))
		}

	case *ast.GenDecl:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))
		if n.Lparen != 0 {
			children = append(children,
				tok(n.Lparen, len("(")),
				tok(n.Rparen, len(")")))
		}

	case *ast.GoStmt:
		children = append(children,
			tok(n.Go, len("go")))

	case *ast.Ident:
		children = append(children,
			tok(n.NamePos, len(n.Name)))

	case *ast.IfStmt:
		children = append(children,
			tok(n.If, len("if")))

	case *ast.ImportSpec:
		// TODO(adonovan): ImportSpec.{Doc,EndPos}?

	case *ast.IncDecStmt:
		children = append(children,
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.IndexExpr:
		children = append(children,
			tok(n.Lbrack, len("[")),
			tok(n.Rbrack, len("]")))

	case *ast.IndexListExpr:
		children = append(children,
			tok(n.Lbrack, len("[")),
			tok(n.Rbrack, len("]")))

	case *ast.InterfaceType:
		children = append(children,
			tok(n.Interface, len("interface")))

	case *ast.KeyValueExpr:
		children = append(children,
			tok(n.Colon, len(":")))

	case *ast.LabeledStmt:
		children = append(children,
			tok(n.Colon, len(":")))

	case *ast.MapType:
		children = append(children,
			tok(n.Map, len("map")))

	case *ast.ParenExpr:
		children = append(children,
			tok(n.Lparen, len("(")),
			tok(n.Rparen, len(")")))

	case *ast.RangeStmt:
		children = append(children,
			tok(n.For, len("for")),
			tok(n.TokPos, len(n.Tok.String())))

	case *ast.ReturnStmt:
		children = append(children,
			tok(n.Return, len("return")))

	case *ast.SelectStmt:
		children = append(children,
			tok(n.Select, len("select")))

	case *ast.SelectorExpr:
		// nop

	case *ast.SendStmt:
		children = append(children,
			tok(n.Arrow, len("<-")))

	case *ast.SliceExpr:
		children = append(children,
			tok(n.Lbrack, len("[")),
			tok(n.Rbrack, len("]")))

	case *ast.StarExpr:
		children = append(children, tok(n.Star, len("*")))

	case *ast.StructType:
		children = append(children, tok(n.Struct, len("struct")))

	case *ast.SwitchStmt:
		children = append(children, tok(n.Switch, len("switch")))

	case *ast.TypeAssertExpr:
		children = append(children,
			tok(n.Lparen-1, len(".")),
			tok(n.Lparen, len("(")),
			tok(n.Rparen, len(")")))

	case *ast.TypeSpec:
		// TODO(adonovan): TypeSpec.{Doc,Comment}?

	case *ast.TypeSwitchStmt:
		children = append(children, tok(n.Switch, len("switch")))

	case *ast.UnaryExpr:
		children = append(children, tok(n.OpPos, len(n.Op.String())))

	case *ast.ValueSpec:
		// TODO(adonovan): ValueSpec.{Doc,Comment}?

	case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt:
		// nop
	}

	// TODO(adonovan): opt: merge the logic of ast.Inspect() into
	// the switch above so we can make interleaved callbacks for
	// both Nodes and Tokens in the right order and avoid the need
	// to sort.
	sort.Sort(byPos(children))

	return children
}

type byPos []ast.Node

func (sl byPos) Len() int {
	return len(sl)
}
func (sl byPos) Less(i, j int) bool {
	return sl[i].Pos() < sl[j].Pos()
}
func (sl byPos) Swap(i, j int) {
	sl[i], sl[j] = sl[j], sl[i]
}

// NodeDescription returns a description of the concrete type of n suitable
// for a user interface.
//
// TODO(adonovan): in some cases (e.g. Field, FieldList, Ident,
// StarExpr) we could be much more specific given the path to the AST
// root.  Perhaps we should do that.
func NodeDescription(n ast.Node) string {
	switch n := n.(type) {
	case *ast.ArrayType:
		return "array type"
	case *ast.AssignStmt:
		return "assignment"
	case *ast.BadDecl:
		return "bad declaration"
	case *ast.BadExpr:
		return "bad expression"
	case *ast.BadStmt:
		return "bad statement"
	case *ast.BasicLit:
		return "basic literal"
	case *ast.BinaryExpr:
		return fmt.Sprintf("binary %s operation", n.Op)
	case *ast.BlockStmt:
		return "block"
	case *ast.BranchStmt:
		switch n.Tok {
		case token.BREAK:
			return "break statement"
		case token.CONTINUE:
			return "continue statement"
		case token.GOTO:
			return "goto statement"
		case token.FALLTHROUGH:
			return "fall-through statement"
		}
	case *ast.CallExpr:
		if len(n.Args) == 1 && !n.Ellipsis.IsValid() {
			return "function call (or conversion)"
		}
		return "function call"
	case *ast.CaseClause:
		return "case clause"
	case *ast.ChanType:
		return "channel type"
	case *ast.CommClause:
		return "communication clause"
	case *ast.Comment:
		return "comment"
	case *ast.CommentGroup:
		return "comment group"
	case *ast.CompositeLit:
		return "composite literal"
	case *ast.DeclStmt:
		return NodeDescription(n.Decl) + " statement"
	case *ast.DeferStmt:
		return "defer statement"
	case *ast.Ellipsis:
		return "ellipsis"
	case *ast.EmptyStmt:
		return "empty statement"
	case *ast.ExprStmt:
		return "expression statement"
	case *ast.Field:
		// Can be any of these:
		// struct {x, y int}  -- struct field(s)
		// struct {T}         -- anon struct field
		// interface {I}      -- interface embedding
		// interface {f()}    -- interface method
		// func (A) func(B) C -- receiver, param(s), result(s)
		return "field/method/parameter"
	case *ast.FieldList:
		return "field/method/parameter list"
	case *ast.File:
		return "source file"
	case *ast.ForStmt:
		return "for loop"
	case *ast.FuncDecl:
		return "function declaration"
	case *ast.FuncLit:
		return "function literal"
	case *ast.FuncType:
		return "function type"
	case *ast.GenDecl:
		switch n.Tok {
		case token.IMPORT:
			return "import declaration"
		case token.CONST:
			return "constant declaration"
		case token.TYPE:
			return "type declaration"
		case token.VAR:
			return "variable declaration"
		}
	case *ast.GoStmt:
		return "go statement"
	case *ast.Ident:
		return "identifier"
	case *ast.IfStmt:
		return "if statement"
	case *ast.ImportSpec:
		return "import specification"
	case *ast.IncDecStmt:
		if n.Tok == token.INC {
			return "increment statement"
		}
		return "decrement statement"
	case *ast.IndexExpr:
		return "index expression"
	case *ast.IndexListExpr:
		return "index list expression"
	case *ast.InterfaceType:
		return "interface type"
	case *ast.KeyValueExpr:
		return "key/value association"
	case *ast.LabeledStmt:
		return "statement label"
	case *ast.MapType:
		return "map type"
	case *ast.Package:
		return "package"
	case *ast.ParenExpr:
		return "parenthesized " + NodeDescription(n.X)
	case *ast.RangeStmt:
		return "range loop"
	case *ast.ReturnStmt:
		return "return statement"
	case *ast.SelectStmt:
		return "select statement"
	case *ast.SelectorExpr:
		return "selector"
	case *ast.SendStmt:
		return "channel send"
	case *ast.SliceExpr:
		return "slice expression"
	case *ast.StarExpr:
		return "*-operation" // load/store expr or pointer type
	case *ast.StructType:
		return "struct type"
	case *ast.SwitchStmt:
		return "switch statement"
	case *ast.TypeAssertExpr:
		return "type assertion"
	case *ast.TypeSpec:
		return "type specification"
	case *ast.TypeSwitchStmt:
		return "type switch"
	case *ast.UnaryExpr:
		return fmt.Sprintf("unary %s operation", n.Op)
	case *ast.ValueSpec:
		return "value specification"

	}
	panic(fmt.Sprintf("unexpected node type: %T", n))
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}


================================================
FILE: go/ast/astutil/enclosing_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil_test

// This file defines tests of PathEnclosingInterval.

// TODO(adonovan): exhaustive tests that run over the whole input
// tree, not just handcrafted examples.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"strings"
	"testing"

	"golang.org/x/tools/go/ast/astutil"
)

// pathToString returns a string containing the concrete types of the
// nodes in path.
func pathToString(path []ast.Node) string {
	var buf bytes.Buffer
	fmt.Fprint(&buf, "[")
	for i, n := range path {
		if i > 0 {
			fmt.Fprint(&buf, " ")
		}
		fmt.Fprint(&buf, strings.TrimPrefix(fmt.Sprintf("%T", n), "*ast."))
	}
	fmt.Fprint(&buf, "]")
	return buf.String()
}

// findInterval parses input and returns the [start, end) positions of
// the first occurrence of substr in input.  f==nil indicates failure;
// an error has already been reported in that case.
func findInterval(t *testing.T, fset *token.FileSet, input, substr string) (f *ast.File, start, end token.Pos) {
	f, err := parser.ParseFile(fset, "<input>", input, 0)
	if err != nil {
		t.Errorf("parse error: %s", err)
		return
	}

	i := strings.Index(input, substr)
	if i < 0 {
		t.Errorf("%q is not a substring of input", substr)
		f = nil
		return
	}

	filePos := fset.File(f.Package)
	return f, filePos.Pos(i), filePos.Pos(i + len(substr))
}

// Common input for following tests.
const input = `
// Hello.
package main
import "fmt"
func f() {}
func main() {
	z := (x + y) // add them
        f() // NB: ExprStmt and its CallExpr have same Pos/End
}

func g[A any, P interface{ctype1| ~ctype2}](a1 A, p1 P) {}

type PT[T constraint] struct{ t T }

func (r recv) method(p param) {}

var v GT[targ1]

var h = g[ targ2, targ3]
`

func TestPathEnclosingInterval_Exact(t *testing.T) {
	type testCase struct {
		substr string // first occurrence of this string indicates interval
		node   string // complete text of expected containing node
	}

	dup := func(s string) testCase { return testCase{s, s} }
	// For the exact tests, we check that a substring is mapped to
	// the canonical string for the node it denotes.
	tests := []testCase{
		{"package",
			input[11 : len(input)-1]},
		{"\npack",
			input[11 : len(input)-1]},
		dup("main"),
		{"import",
			"import \"fmt\""},
		dup("\"fmt\""),
		{"\nfunc f() {}\n",
			"func f() {}"},
		{"x ",
			"x"},
		{" y",
			"y"},
		dup("z"),
		{" + ",
			"x + y"},
		{" :=",
			"z := (x + y)"},
		dup("x + y"),
		dup("(x + y)"),
		{" (x + y) ",
			"(x + y)"},
		{" (x + y) // add",
			"(x + y)"},
		{"func",
			"func f() {}"},
		dup("func f() {}"),
		{"\nfun",
			"func f() {}"},
		{" f",
			"f"},
		dup("[A any, P interface{ctype1| ~ctype2}]"),
		{"[", "[A any, P interface{ctype1| ~ctype2}]"},
		dup("A"),
		{" any", "any"},
		dup("ctype1"),
		{"|", "ctype1| ~ctype2"},
		dup("ctype2"),
		{"~", "~ctype2"},
		dup("~ctype2"),
		{" ~ctype2", "~ctype2"},
		{"]", "[A any, P interface{ctype1| ~ctype2}]"},
		dup("a1"),
		dup("a1 A"),
		dup("(a1 A, p1 P)"),
		dup("type PT[T constraint] struct{ t T }"),
		dup("PT"),
		dup("[T constraint]"),
		dup("constraint"),
		dup("targ1"),
		{" targ2", "targ2"},
		dup("g[ targ2, targ3]"),
	}
	for _, test := range tests {
		f, start, end := findInterval(t, new(token.FileSet), input, test.substr)
		if f == nil {
			continue
		}

		path, exact := astutil.PathEnclosingInterval(f, start, end)
		if !exact {
			t.Errorf("PathEnclosingInterval(%q) not exact", test.substr)
			continue
		}

		if len(path) == 0 {
			if test.node != "" {
				t.Errorf("PathEnclosingInterval(%q).path: got [], want %q",
					test.substr, test.node)
			}
			continue
		}

		if got := input[path[0].Pos():path[0].End()]; got != test.node {
			t.Errorf("PathEnclosingInterval(%q): got %q, want %q (path was %s)",
				test.substr, got, test.node, pathToString(path))
			continue
		}
	}
}

func TestPathEnclosingInterval_Paths(t *testing.T) {
	type testCase struct {
		substr string // first occurrence of this string indicates interval
		path   string // the pathToString(),exact of the expected path
	}
	// For these tests, we check only the path of the enclosing
	// node, but not its complete text because it's often quite
	// large when !exact.
	tests := []testCase{
		{"// add",
			"[BlockStmt FuncDecl File],false"},
		{"(x + y",
			"[ParenExpr AssignStmt BlockStmt FuncDecl File],false"},
		{"x +",
			"[BinaryExpr ParenExpr AssignStmt BlockStmt FuncDecl File],false"},
		{"z := (x",
			"[AssignStmt BlockStmt FuncDecl File],false"},
		{"func f",
			"[FuncDecl File],false"},
		{"func f()",
			"[FuncDecl File],false"},
		{" f()",
			"[FuncDecl File],false"},
		{"() {}",
			"[FuncDecl File],false"},
		{"// Hello",
			"[File],false"},
		{" f",
			"[Ident FuncDecl File],true"},
		{"func ",
			"[FuncDecl File],true"},
		{"mai",
			"[Ident File],true"},
		{"f() // NB",
			"[CallExpr ExprStmt BlockStmt FuncDecl File],true"},
		{" any", "[Ident Field FieldList FuncType FuncDecl File],true"},
		{"|", "[BinaryExpr Field FieldList InterfaceType Field FieldList FuncType FuncDecl File],true"},
		{"ctype2",
			"[Ident UnaryExpr BinaryExpr Field FieldList InterfaceType Field FieldList FuncType FuncDecl File],true"},
		{"a1", "[Ident Field FieldList FuncType FuncDecl File],true"},
		{"PT[T constraint]", "[TypeSpec GenDecl File],false"},
		{"[T constraint]", "[FieldList TypeSpec GenDecl File],true"},
		{"targ2", "[Ident IndexListExpr ValueSpec GenDecl File],true"},
		{"p param", "[Field FieldList FuncType FuncDecl File],true"}, // FuncType is present for FuncDecl.Params (etc)
		{"r recv", "[Field FieldList FuncDecl File],true"},           // no FuncType for FuncDecl.Recv
	}
	for _, test := range tests {
		f, start, end := findInterval(t, new(token.FileSet), input, test.substr)
		if f == nil {
			continue
		}

		path, exact := astutil.PathEnclosingInterval(f, start, end)
		if got := fmt.Sprintf("%s,%v", pathToString(path), exact); got != test.path {
			t.Errorf("PathEnclosingInterval(%q): got %q, want %q",
				test.substr, got, test.path)
			continue
		}
	}
}


================================================
FILE: go/ast/astutil/imports.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package astutil contains common utilities for working with the Go AST.
package astutil // import "golang.org/x/tools/go/ast/astutil"

import (
	"fmt"
	"go/ast"
	"go/token"
	"reflect"
	"slices"
	"strconv"
	"strings"
)

// AddImport adds the import path to the file f, if absent.
func AddImport(fset *token.FileSet, f *ast.File, path string) (added bool) {
	return AddNamedImport(fset, f, "", path)
}

// AddNamedImport adds the import with the given name and path to the file f, if absent.
// If name is not empty, it is used to rename the import.
//
// For example, calling
//
//	AddNamedImport(fset, f, "pathpkg", "path")
//
// adds
//
//	import pathpkg "path"
func AddNamedImport(fset *token.FileSet, f *ast.File, name, path string) (added bool) {
	if imports(f, name, path) {
		return false
	}

	newImport := &ast.ImportSpec{
		Path: &ast.BasicLit{
			Kind:  token.STRING,
			Value: strconv.Quote(path),
		},
	}
	if name != "" {
		newImport.Name = &ast.Ident{Name: name}
	}

	// Find an import decl to add to.
	// The goal is to find an existing import
	// whose import path has the longest shared
	// prefix with path.
	var (
		bestMatch  = -1         // length of longest shared prefix
		lastImport = -1         // index in f.Decls of the file's final import decl
		impDecl    *ast.GenDecl // import decl containing the best match
		impIndex   = -1         // spec index in impDecl containing the best match

		isThirdPartyPath = isThirdParty(path)
	)
	for i, decl := range f.Decls {
		gen, ok := decl.(*ast.GenDecl)
		if ok && gen.Tok == token.IMPORT {
			lastImport = i
			// Do not add to import "C", to avoid disrupting the
			// association with its doc comment, breaking cgo.
			if declImports(gen, "C") {
				continue
			}

			// Match an empty import decl if that's all that is available.
			if len(gen.Specs) == 0 && bestMatch == -1 {
				impDecl = gen
			}

			// Compute longest shared prefix with imports in this group and find best
			// matched import spec.
			// 1. Always prefer import spec with longest shared prefix.
			// 2. While match length is 0,
			// - for stdlib package: prefer first import spec.
			// - for third party package: prefer first third party import spec.
			// We cannot use last import spec as best match for third party package
			// because grouped imports are usually placed last by goimports -local
			// flag.
			// See issue #19190.
			seenAnyThirdParty := false
			for j, spec := range gen.Specs {
				impspec := spec.(*ast.ImportSpec)
				p := importPath(impspec)
				n := matchLen(p, path)
				if n > bestMatch || (bestMatch == 0 && !seenAnyThirdParty && isThirdPartyPath) {
					bestMatch = n
					impDecl = gen
					impIndex = j
				}
				seenAnyThirdParty = seenAnyThirdParty || isThirdParty(p)
			}
		}
	}

	// If no import decl found, add one after the last import.
	if impDecl == nil {
		impDecl = &ast.GenDecl{
			Tok: token.IMPORT,
		}
		if lastImport >= 0 {
			impDecl.TokPos = f.Decls[lastImport].End()
		} else {
			// There are no existing imports.
			// Our new import, preceded by a blank line,  goes after the package declaration
			// and after the comment, if any, that starts on the same line as the
			// package declaration.
			impDecl.TokPos = f.Package

			file := fset.File(f.Package)
			pkgLine := file.Line(f.Package)
			for _, c := range f.Comments {
				if file.Line(c.Pos()) > pkgLine {
					break
				}
				// +2 for a blank line
				impDecl.TokPos = c.End() + 2
			}
		}
		f.Decls = append(f.Decls, nil)
		copy(f.Decls[lastImport+2:], f.Decls[lastImport+1:])
		f.Decls[lastImport+1] = impDecl
	}

	// Insert new import at insertAt.
	insertAt := 0
	if impIndex >= 0 {
		// insert after the found import
		insertAt = impIndex + 1
	}
	impDecl.Specs = append(impDecl.Specs, nil)
	copy(impDecl.Specs[insertAt+1:], impDecl.Specs[insertAt:])
	impDecl.Specs[insertAt] = newImport
	pos := impDecl.Pos()
	if insertAt > 0 {
		// If there is a comment after an existing import, preserve the comment
		// position by adding the new import after the comment.
		if spec, ok := impDecl.Specs[insertAt-1].(*ast.ImportSpec); ok && spec.Comment != nil {
			pos = spec.Comment.End()
		} else {
			// Assign same position as the previous import,
			// so that the sorter sees it as being in the same block.
			pos = impDecl.Specs[insertAt-1].Pos()
		}
	}
	if newImport.Name != nil {
		newImport.Name.NamePos = pos
	}
	updateBasicLitPos(newImport.Path, pos)
	newImport.EndPos = pos

	// Clean up parens. impDecl contains at least one spec.
	if len(impDecl.Specs) == 1 {
		// Remove unneeded parens.
		impDecl.Lparen = token.NoPos
	} else if !impDecl.Lparen.IsValid() {
		// impDecl needs parens added.
		impDecl.Lparen = impDecl.Specs[0].Pos()
	}

	f.Imports = append(f.Imports, newImport)

	if len(f.Decls) <= 1 {
		return true
	}

	// Merge all the import declarations into the first one.
	var first *ast.GenDecl
	for i := 0; i < len(f.Decls); i++ {
		decl := f.Decls[i]
		gen, ok := decl.(*ast.GenDecl)
		if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
			continue
		}
		if first == nil {
			first = gen
			continue // Don't touch the first one.
		}
		// We now know there is more than one package in this import
		// declaration. Ensure that it ends up parenthesized.
		first.Lparen = first.Pos()
		// Move the imports of the other import declaration to the first one.
		for _, spec := range gen.Specs {
			updateBasicLitPos(spec.(*ast.ImportSpec).Path, first.Pos())
			first.Specs = append(first.Specs, spec)
		}
		f.Decls = slices.Delete(f.Decls, i, i+1)
		i--
	}

	return true
}

func isThirdParty(importPath string) bool {
	// Third party package import path usually contains "." (".com", ".org", ...)
	// This logic is taken from golang.org/x/tools/imports package.
	return strings.Contains(importPath, ".")
}

// DeleteImport deletes the import path from the file f, if present.
// If there are duplicate import declarations, all matching ones are deleted.
func DeleteImport(fset *token.FileSet, f *ast.File, path string) (deleted bool) {
	return DeleteNamedImport(fset, f, "", path)
}

// DeleteNamedImport deletes the import with the given name and path from the file f, if present.
// If there are duplicate import declarations, all matching ones are deleted.
func DeleteNamedImport(fset *token.FileSet, f *ast.File, name, path string) (deleted bool) {
	var (
		delspecs    = make(map[*ast.ImportSpec]bool)
		delcomments = make(map[*ast.CommentGroup]bool)
	)

	// Find the import nodes that import path, if any.
	for i := 0; i < len(f.Decls); i++ {
		gen, ok := f.Decls[i].(*ast.GenDecl)
		if !ok || gen.Tok != token.IMPORT {
			continue
		}
		for j := 0; j < len(gen.Specs); j++ {
			impspec := gen.Specs[j].(*ast.ImportSpec)
			if importName(impspec) != name || importPath(impspec) != path {
				continue
			}

			// We found an import spec that imports path.
			// Delete it.
			delspecs[impspec] = true
			deleted = true
			gen.Specs = slices.Delete(gen.Specs, j, j+1)

			// If this was the last import spec in this decl,
			// delete the decl, too.
			if len(gen.Specs) == 0 {
				f.Decls = slices.Delete(f.Decls, i, i+1)
				i--
				break
			} else if len(gen.Specs) == 1 {
				if impspec.Doc != nil {
					delcomments[impspec.Doc] = true
				}
				if impspec.Comment != nil {
					delcomments[impspec.Comment] = true
				}
				for _, cg := range f.Comments {
					// Found comment on the same line as the import spec.
					if cg.End() < impspec.Pos() && fset.Position(cg.End()).Line == fset.Position(impspec.Pos()).Line {
						delcomments[cg] = true
						break
					}
				}

				spec := gen.Specs[0].(*ast.ImportSpec)

				// Move the documentation right after the import decl.
				if spec.Doc != nil {
					for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Doc.Pos()).Line {
						fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
					}
				}
				for _, cg := range f.Comments {
					if cg.End() < spec.Pos() && fset.Position(cg.End()).Line == fset.Position(spec.Pos()).Line {
						for fset.Position(gen.TokPos).Line+1 < fset.Position(spec.Pos()).Line {
							fset.File(gen.TokPos).MergeLine(fset.Position(gen.TokPos).Line)
						}
						break
					}
				}
			}
			if j > 0 {
				lastImpspec := gen.Specs[j-1].(*ast.ImportSpec)
				lastLine := fset.PositionFor(lastImpspec.Path.ValuePos, false).Line
				line := fset.PositionFor(impspec.Path.ValuePos, false).Line

				// We deleted an entry but now there may be
				// a blank line-sized hole where the import was.
				if line-lastLine > 1 || !gen.Rparen.IsValid() {
					// There was a blank line immediately preceding the deleted import,
					// so there's no need to close the hole. The right parenthesis is
					// invalid after AddImport to an import statement without parenthesis.
					// Do nothing.
				} else if line != fset.File(gen.Rparen).LineCount() {
					// There was no blank line. Close the hole.
					fset.File(gen.Rparen).MergeLine(line)
				}
			}
			j--
		}
	}

	// Delete imports from f.Imports.
	before := len(f.Imports)
	f.Imports = slices.DeleteFunc(f.Imports, func(imp *ast.ImportSpec) bool {
		_, ok := delspecs[imp]
		return ok
	})
	if len(f.Imports)+len(delspecs) != before {
		// This can happen when the AST is invalid (i.e. imports differ between f.Decls and f.Imports).
		panic(fmt.Sprintf("deleted specs from Decls but not Imports: %v", delspecs))
	}

	// Delete comments from f.Comments.
	f.Comments = slices.DeleteFunc(f.Comments, func(cg *ast.CommentGroup) bool {
		_, ok := delcomments[cg]
		return ok
	})

	return
}

// RewriteImport rewrites any import of path oldPath to path newPath.
func RewriteImport(fset *token.FileSet, f *ast.File, oldPath, newPath string) (rewrote bool) {
	for _, imp := range f.Imports {
		if importPath(imp) == oldPath {
			rewrote = true
			// record old End, because the default is to compute
			// it using the length of imp.Path.Value.
			imp.EndPos = imp.End()
			imp.Path.Value = strconv.Quote(newPath)
		}
	}
	return
}

// UsesImport reports whether a given import is used.
// The provided File must have been parsed with syntactic object resolution
// (not using go/parser.SkipObjectResolution).
func UsesImport(f *ast.File, path string) (used bool) {
	if f.Scope == nil {
		panic("file f was not parsed with syntactic object resolution")
	}
	spec := importSpec(f, path)
	if spec == nil {
		return
	}

	name := spec.Name.String()
	switch name {
	case "<nil>":
		// If the package name is not explicitly specified,
		// make an educated guess. This is not guaranteed to be correct.
		lastSlash := strings.LastIndex(path, "/")
		if lastSlash == -1 {
			name = path
		} else {
			name = path[lastSlash+1:]
		}
	case "_", ".":
		// Not sure if this import is used - err on the side of caution.
		return true
	}

	ast.Walk(visitFn(func(n ast.Node) {
		sel, ok := n.(*ast.SelectorExpr)
		if ok && isTopName(sel.X, name) {
			used = true
		}
	}), f)

	return
}

type visitFn func(node ast.Node)

func (fn visitFn) Visit(node ast.Node) ast.Visitor {
	fn(node)
	return fn
}

// imports reports whether f has an import with the specified name and path.
func imports(f *ast.File, name, path string) bool {
	for _, s := range f.Imports {
		if importName(s) == name && importPath(s) == path {
			return true
		}
	}
	return false
}

// importSpec returns the import spec if f imports path,
// or nil otherwise.
func importSpec(f *ast.File, path string) *ast.ImportSpec {
	for _, s := range f.Imports {
		if importPath(s) == path {
			return s
		}
	}
	return nil
}

// importName returns the name of s,
// or "" if the import is not named.
func importName(s *ast.ImportSpec) string {
	if s.Name == nil {
		return ""
	}
	return s.Name.Name
}

// importPath returns the unquoted import path of s,
// or "" if the path is not properly quoted.
func importPath(s *ast.ImportSpec) string {
	t, err := strconv.Unquote(s.Path.Value)
	if err != nil {
		return ""
	}
	return t
}

// declImports reports whether gen contains an import of path.
func declImports(gen *ast.GenDecl, path string) bool {
	if gen.Tok != token.IMPORT {
		return false
	}
	for _, spec := range gen.Specs {
		impspec := spec.(*ast.ImportSpec)
		if importPath(impspec) == path {
			return true
		}
	}
	return false
}

// matchLen returns the length of the longest path segment prefix shared by x and y.
func matchLen(x, y string) int {
	n := 0
	for i := 0; i < len(x) && i < len(y) && x[i] == y[i]; i++ {
		if x[i] == '/' {
			n++
		}
	}
	return n
}

// isTopName returns true if n is a top-level unresolved identifier with the given name.
func isTopName(n ast.Expr, name string) bool {
	id, ok := n.(*ast.Ident)
	return ok && id.Name == name && id.Obj == nil
}

// Imports returns the file imports grouped by paragraph.
func Imports(fset *token.FileSet, f *ast.File) [][]*ast.ImportSpec {
	var groups [][]*ast.ImportSpec

	for _, decl := range f.Decls {
		genDecl, ok := decl.(*ast.GenDecl)
		if !ok || genDecl.Tok != token.IMPORT {
			break
		}

		group := []*ast.ImportSpec{}

		var lastLine int
		for _, spec := range genDecl.Specs {
			importSpec := spec.(*ast.ImportSpec)
			pos := importSpec.Path.ValuePos
			line := fset.Position(pos).Line
			if lastLine > 0 && pos > 0 && line-lastLine > 1 {
				groups = append(groups, group)
				group = []*ast.ImportSpec{}
			}
			group = append(group, importSpec)
			lastLine = line
		}
		groups = append(groups, group)
	}

	return groups
}

// updateBasicLitPos updates lit.Pos,
// ensuring that lit.End (if set) is displaced by the same amount.
// (See https://go.dev/issue/76395.)
func updateBasicLitPos(lit *ast.BasicLit, pos token.Pos) {
	len := lit.End() - lit.Pos()
	lit.ValuePos = pos
	// TODO(adonovan): after go1.26, simplify to:
	//   lit.ValueEnd = pos + len
	v := reflect.ValueOf(lit).Elem().FieldByName("ValueEnd")
	if v.IsValid() && v.Int() != 0 {
		v.SetInt(int64(pos + len))
	}
}


================================================
FILE: go/ast/astutil/imports_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"bytes"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"reflect"
	"strconv"
	"testing"
)

var fset = token.NewFileSet()

func parse(t *testing.T, name, in string) *ast.File {
	file, err := parser.ParseFile(fset, name, in, parser.ParseComments)
	if err != nil {
		t.Fatalf("%s parse: %v", name, err)
	}
	return file
}

func print(t *testing.T, name string, f *ast.File) string {
	var buf bytes.Buffer
	if err := format.Node(&buf, fset, f); err != nil {
		t.Fatalf("%s gofmt: %v", name, err)
	}
	return buf.String()
}

type test struct {
	name       string
	renamedPkg string
	pkg        string
	in         string
	out        string
	unchanged  bool // Expect added/deleted return value to be false.
}

var addTests = []test{
	{
		name: "leave os alone",
		pkg:  "os",
		in: `package main

import (
	"os"
)
`,
		out: `package main

import (
	"os"
)
`,
		unchanged: true,
	},
	{
		name: "import.1",
		pkg:  "os",
		in: `package main
`,
		out: `package main

import "os"
`,
	},
	{
		name: "import.2",
		pkg:  "os",
		in: `package main

// Comment
import "C"
`,
		out: `package main

// Comment
import "C"
import "os"
`,
	},
	{
		name: "import.3",
		pkg:  "os",
		in: `package main

// Comment
import "C"

import (
	"io"
	"utf8"
)
`,
		out: `package main

// Comment
import "C"

import (
	"io"
	"os"
	"utf8"
)
`,
	},
	{
		name: "import.17",
		pkg:  "x/y/z",
		in: `package main

// Comment
import "C"

import (
	"a"
	"b"

	"x/w"

	"d/f"
)
`,
		out: `package main

// Comment
import "C"

import (
	"a"
	"b"

	"x/w"
	"x/y/z"

	"d/f"
)
`,
	},
	{
		name: "issue #19190",
		pkg:  "x.org/y/z",
		in: `package main

// Comment
import "C"

import (
	"bytes"
	"os"

	"d.com/f"
)
`,
		out: `package main

// Comment
import "C"

import (
	"bytes"
	"os"

	"d.com/f"
	"x.org/y/z"
)
`,
	},
	{
		name: "issue #19190 with existing grouped import packages",
		pkg:  "x.org/y/z",
		in: `package main

// Comment
import "C"

import (
	"bytes"
	"os"

	"c.com/f"
	"d.com/f"

	"y.com/a"
	"y.com/b"
	"y.com/c"
)
`,
		out: `package main

// Comment
import "C"

import (
	"bytes"
	"os"

	"c.com/f"
	"d.com/f"
	"x.org/y/z"

	"y.com/a"
	"y.com/b"
	"y.com/c"
)
`,
	},
	{
		name: "issue #19190 - match score is still respected",
		pkg:  "y.org/c",
		in: `package main

import (
	"x.org/a"

	"y.org/b"
)
`,
		out: `package main

import (
	"x.org/a"

	"y.org/b"
	"y.org/c"
)
`,
	},
	{
		name: "import into singular group",
		pkg:  "bytes",
		in: `package main

import "os"

`,
		out: `package main

import (
	"bytes"
	"os"
)
`,
	},
	{
		name: "import into singular group with comment",
		pkg:  "bytes",
		in: `package main

import /* why */ /* comment here? */ "os"

`,
		out: `package main

import /* why */ /* comment here? */ (
	"bytes"
	"os"
)
`,
	},
	{
		name: "import into group with leading comment",
		pkg:  "strings",
		in: `package main

import (
	// comment before bytes
	"bytes"
	"os"
)

`,
		out: `package main

import (
	// comment before bytes
	"bytes"
	"os"
	"strings"
)
`,
	},
	{
		name:       "",
		renamedPkg: "fmtpkg",
		pkg:        "fmt",
		in: `package main

import "os"

`,
		out: `package main

import (
	fmtpkg "fmt"
	"os"
)
`,
	},
	{
		name: "struct comment",
		pkg:  "time",
		in: `package main

// This is a comment before a struct.
type T struct {
	t  time.Time
}
`,
		out: `package main

import "time"

// This is a comment before a struct.
type T struct {
	t time.Time
}
`,
	},
	{
		name: "issue 8729 import C",
		pkg:  "time",
		in: `package main

import "C"

// comment
type T time.Time
`,
		out: `package main

import "C"
import "time"

// comment
type T time.Time
`,
	},
	{
		name: "issue 8729 empty import",
		pkg:  "time",
		in: `package main

import ()

// comment
type T time.Time
`,
		out: `package main

import "time"

// comment
type T time.Time
`,
	},
	{
		name: "issue 8729 comment on package line",
		pkg:  "time",
		in: `package main // comment

type T time.Time
`,
		out: `package main // comment

import "time"

type T time.Time
`,
	},
	{
		name: "issue 8729 comment after package",
		pkg:  "time",
		in: `package main
// comment

type T time.Time
`,
		out: `package main

import "time"

// comment

type T time.Time
`,
	},
	{
		name: "issue 8729 comment before and on package line",
		pkg:  "time",
		in: `// comment before
package main // comment on

type T time.Time
`,
		out: `// comment before
package main // comment on

import "time"

type T time.Time
`,
	},

	// Issue 9961: Match prefixes using path segments rather than bytes
	{
		name: "issue 9961",
		pkg:  "regexp",
		in: `package main

import (
	"flag"
	"testing"

	"rsc.io/p"
)
`,
		out: `package main

import (
	"flag"
	"regexp"
	"testing"

	"rsc.io/p"
)
`,
	},
	// Issue 10337: Preserve comment position
	{
		name: "issue 10337",
		pkg:  "fmt",
		in: `package main

import (
	"bytes" // a
	"log" // c
)
`,
		out: `package main

import (
	"bytes" // a
	"fmt"
	"log" // c
)
`,
	},
	{
		name: "issue 10337 new import at the start",
		pkg:  "bytes",
		in: `package main

import (
	"fmt" // b
	"log" // c
)
`,
		out: `package main

import (
	"bytes"
	"fmt" // b
	"log" // c
)
`,
	},
	{
		name: "issue 10337 new import at the end",
		pkg:  "log",
		in: `package main

import (
	"bytes" // a
	"fmt" // b
)
`,
		out: `package main

import (
	"bytes" // a
	"fmt"   // b
	"log"
)
`,
	},
	// Issue 14075: Merge import declarations
	{
		name: "issue 14075",
		pkg:  "bufio",
		in: `package main

import "bytes"
import "fmt"
`,
		out: `package main

import (
	"bufio"
	"bytes"
	"fmt"
)
`,
	},
	{
		name: "issue 14075 update position",
		pkg:  "bufio",
		in: `package main

import "bytes"
import (
	"fmt"
)
`,
		out: `package main

import (
	"bufio"
	"bytes"
	"fmt"
)
`,
	},
	{
		name: `issue 14075 ignore import "C"`,
		pkg:  "bufio",
		in: `package main

// Comment
import "C"

import "bytes"
import "fmt"
`,
		out: `package main

// Comment
import "C"

import (
	"bufio"
	"bytes"
	"fmt"
)
`,
	},
	{
		name: `issue 14075 ignore adjacent import "C"`,
		pkg:  "bufio",
		in: `package main

// Comment
import "C"
import "fmt"
`,
		out: `package main

// Comment
import "C"
import (
	"bufio"
	"fmt"
)
`,
	},
	{
		name: `issue 14075 ignore adjacent import "C" (without factored import)`,
		pkg:  "bufio",
		in: `package main

// Comment
import "C"
import "fmt"
`,
		out: `package main

// Comment
import "C"
import (
	"bufio"
	"fmt"
)
`,
	},
	{
		name: `issue 14075 ignore single import "C"`,
		pkg:  "bufio",
		in: `package main

// Comment
import "C"
`,
		out: `package main

// Comment
import "C"
import "bufio"
`,
	},
	{
		name: `issue 17212 several single-import lines with shared prefix ending in a slash`,
		pkg:  "net/http",
		in: `package main

import "bufio"
import "net/url"
`,
		out: `package main

import (
	"bufio"
	"net/http"
	"net/url"
)
`,
	},
	{
		name: `issue 17212 block imports lines with shared prefix ending in a slash`,
		pkg:  "net/http",
		in: `package main

import (
	"bufio"
	"net/url"
)
`,
		out: `package main

import (
	"bufio"
	"net/http"
	"net/url"
)
`,
	},
	{
		name: `issue 17213 many single-import lines`,
		pkg:  "fmt",
		in: `package main

import "bufio"
import "bytes"
import "errors"
`,
		out: `package main

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
)
`,
	},

	// Issue 28605: Add specified import, even if that import path is imported under another name
	{
		name:       "issue 28605 add unnamed path",
		renamedPkg: "",
		pkg:        "path",
		in: `package main

import (
	. "path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
	},
	{
		name:       "issue 28605 add pathpkg-renamed path",
		renamedPkg: "pathpkg",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	_ "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
	},
	{
		name:       "issue 28605 add blank identifier path",
		renamedPkg: "_",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
	},
	{
		name:       "issue 28605 add dot import path",
		renamedPkg: ".",
		pkg:        "path",
		in: `package main

import (
	"path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
	},

	{
		name:       "duplicate import declarations, add existing one",
		renamedPkg: "f",
		pkg:        "fmt",
		in: `package main

import "fmt"
import "fmt"
import f "fmt"
import f "fmt"
`,
		out: `package main

import "fmt"
import "fmt"
import f "fmt"
import f "fmt"
`,
		unchanged: true,
	},
}

func TestAddImport(t *testing.T) {
	for _, test := range addTests {
		file := parse(t, test.name, test.in)
		var before bytes.Buffer
		ast.Fprint(&before, fset, file, nil)
		added := AddNamedImport(fset, file, test.renamedPkg, test.pkg)
		if got := print(t, test.name, file); got != test.out {
			t.Errorf("first run: %s:\ngot: %s\nwant: %s", test.name, got, test.out)
			var after bytes.Buffer
			ast.Fprint(&after, fset, file, nil)
			t.Logf("AST before:\n%s\nAST after:\n%s\n", before.String(), after.String())
		}
		if got, want := added, !test.unchanged; got != want {
			t.Errorf("first run: %s: added = %v, want %v", test.name, got, want)
		}

		// AddNamedImport should be idempotent. Verify that by calling it again,
		// expecting no change to the AST, and the returned added value to always be false.
		added = AddNamedImport(fset, file, test.renamedPkg, test.pkg)
		if got := print(t, test.name, file); got != test.out {
			t.Errorf("second run: %s:\ngot: %s\nwant: %s", test.name, got, test.out)
		}
		if got, want := added, false; got != want {
			t.Errorf("second run: %s: added = %v, want %v", test.name, got, want)
		}
	}
}

func TestDoubleAddImport(t *testing.T) {
	file := parse(t, "doubleimport", "package main\n")
	AddImport(fset, file, "os")
	AddImport(fset, file, "bytes")
	want := `package main

import (
	"bytes"
	"os"
)
`
	if got := print(t, "doubleimport", file); got != want {
		t.Errorf("got: %s\nwant: %s", got, want)
	}
}

func TestDoubleAddNamedImport(t *testing.T) {
	file := parse(t, "doublenamedimport", "package main\n")
	AddNamedImport(fset, file, "o", "os")
	AddNamedImport(fset, file, "i", "io")
	want := `package main

import (
	i "io"
	o "os"
)
`
	if got := print(t, "doublenamedimport", file); got != want {
		t.Errorf("got: %s\nwant: %s", got, want)
	}
}

// Part of issue 8729.
func TestDoubleAddImportWithDeclComment(t *testing.T) {
	file := parse(t, "doubleimport", `package main

import (
)

// comment
type I int
`)
	// The AddImport order here matters.
	AddImport(fset, file, "golang.org/x/tools/go/ast/astutil")
	AddImport(fset, file, "os")
	want := `package main

import (
	"golang.org/x/tools/go/ast/astutil"
	"os"
)

// comment
type I int
`
	if got := print(t, "doubleimport_with_decl_comment", file); got != want {
		t.Errorf("got: %s\nwant: %s", got, want)
	}
}

var deleteTests = []test{
	{
		name: "import.4",
		pkg:  "os",
		in: `package main

import (
	"os"
)
`,
		out: `package main
`,
	},
	{
		name: "import.5",
		pkg:  "os",
		in: `package main

// Comment
import "C"
import "os"
`,
		out: `package main

// Comment
import "C"
`,
	},
	{
		name: "import.6",
		pkg:  "os",
		in: `package main

// Comment
import "C"

import (
	"io"
	"os"
	"utf8"
)
`,
		out: `package main

// Comment
import "C"

import (
	"io"
	"utf8"
)
`,
	},
	{
		name: "import.7",
		pkg:  "io",
		in: `package main

import (
	"io"   // a
	"os"   // b
	"utf8" // c
)
`,
		out: `package main

import (
	// a
	"os"   // b
	"utf8" // c
)
`,
	},
	{
		name: "import.8",
		pkg:  "os",
		in: `package main

import (
	"io"   // a
	"os"   // b
	"utf8" // c
)
`,
		out: `package main

import (
	"io" // a
	// b
	"utf8" // c
)
`,
	},
	{
		name: "import.9",
		pkg:  "utf8",
		in: `package main

import (
	"io"   // a
	"os"   // b
	"utf8" // c
)
`,
		out: `package main

import (
	"io" // a
	"os" // b
	// c
)
`,
	},
	{
		name: "import.10",
		pkg:  "io",
		in: `package main

import (
	"io"
	"os"
	"utf8"
)
`,
		out: `package main

import (
	"os"
	"utf8"
)
`,
	},
	{
		name: "import.11",
		pkg:  "os",
		in: `package main

import (
	"io"
	"os"
	"utf8"
)
`,
		out: `package main

import (
	"io"
	"utf8"
)
`,
	},
	{
		name: "import.12",
		pkg:  "utf8",
		in: `package main

import (
	"io"
	"os"
	"utf8"
)
`,
		out: `package main

import (
	"io"
	"os"
)
`,
	},
	{
		name: "handle.raw.quote.imports",
		pkg:  "os",
		in:   "package main\n\nimport `os`",
		out: `package main
`,
	},
	{
		name: "import.13",
		pkg:  "io",
		in: `package main

import (
	"fmt"

	"io"
	"os"
	"utf8"

	"go/format"
)
`,
		out: `package main

import (
	"fmt"

	"os"
	"utf8"

	"go/format"
)
`,
	},
	{
		name: "import.14",
		pkg:  "io",
		in: `package main

import (
	"fmt" // a

	"io"   // b
	"os"   // c
	"utf8" // d

	"go/format" // e
)
`,
		out: `package main

import (
	"fmt" // a

	// b
	"os"   // c
	"utf8" // d

	"go/format" // e
)
`,
	},
	{
		name: "import.15",
		pkg:  "double",
		in: `package main

import (
	"double"
	"double"
)
`,
		out: `package main
`,
	},
	{
		name: "import.16",
		pkg:  "bubble",
		in: `package main

import (
	"toil"
	"bubble"
	"bubble"
	"trouble"
)
`,
		out: `package main

import (
	"toil"
	"trouble"
)
`,
	},
	{
		name: "import.17",
		pkg:  "quad",
		in: `package main

import (
	"quad"
	"quad"
)

import (
	"quad"
	"quad"
)
`,
		out: `package main
`,
	},
	{
		name:       "import.18",
		renamedPkg: "x",
		pkg:        "fmt",
		in: `package main

import (
	"fmt"
	x "fmt"
)
`,
		out: `package main

import (
	"fmt"
)
`,
	},
	{
		name:       "import.18",
		renamedPkg: "x",
		pkg:        "fmt",
		in: `package main

import x "fmt"
import y "fmt"
`,
		out: `package main

import y "fmt"
`,
	},
	// Issue #15432, #18051
	{
		name: "import.19",
		pkg:  "fmt",
		in: `package main

import (
	"fmt"

	// Some comment.
	"io"
)`,
		out: `package main

import (
	// Some comment.
	"io"
)
`,
	},
	{
		name: "import.20",
		pkg:  "fmt",
		in: `package main

import (
	"fmt"

	// Some
	// comment.
	"io"
)`,
		out: `package main

import (
	// Some
	// comment.
	"io"
)
`,
	},
	{
		name: "import.21",
		pkg:  "fmt",
		in: `package main

import (
	"fmt"

	/*
		Some
		comment.
	*/
	"io"
)`,
		out: `package main

import (
	/*
		Some
		comment.
	*/
	"io"
)
`,
	},
	{
		name: "import.22",
		pkg:  "fmt",
		in: `package main

import (
	/* Some */
	// comment.
	"io"
	"fmt"
)`,
		out: `package main

import (
	/* Some */
	// comment.
	"io"
)
`,
	},
	{
		name: "import.23",
		pkg:  "fmt",
		in: `package main

import (
	// comment 1
	"fmt"
	// comment 2
	"io"
)`,
		out: `package main

import (
	// comment 2
	"io"
)
`,
	},
	{
		name: "import.24",
		pkg:  "fmt",
		in: `package main

import (
	"fmt" // comment 1
	"io" // comment 2
)`,
		out: `package main

import (
	"io" // comment 2
)
`,
	},
	{
		name: "import.25",
		pkg:  "fmt",
		in: `package main

import (
	"fmt"
	/* comment */ "io"
)`,
		out: `package main

import (
	/* comment */ "io"
)
`,
	},
	{
		name: "import.26",
		pkg:  "fmt",
		in: `package main

import (
	"fmt"
	"io" /* comment */
)`,
		out: `package main

import (
	"io" /* comment */
)
`,
	},
	{
		name: "import.27",
		pkg:  "fmt",
		in: `package main

import (
	"fmt" /* comment */
	"io"
)`,
		out: `package main

import (
	"io"
)
`,
	},
	{
		name: "import.28",
		pkg:  "fmt",
		in: `package main

import (
	/* comment */  "fmt"
	"io"
)`,
		out: `package main

import (
	"io"
)
`,
	},
	{
		name: "import.29",
		pkg:  "fmt",
		in: `package main

// comment 1
import (
	"fmt"
	"io" // comment 2
)`,
		out: `package main

// comment 1
import (
	"io" // comment 2
)
`,
	},
	{
		name: "import.30",
		pkg:  "fmt",
		in: `package main

// comment 1
import (
	"fmt" // comment 2
	"io"
)`,
		out: `package main

// comment 1
import (
	"io"
)
`,
	},
	{
		name: "import.31",
		pkg:  "fmt",
		in: `package main

// comment 1
import (
	"fmt"
	/* comment 2 */ "io"
)`,
		out: `package main

// comment 1
import (
	/* comment 2 */ "io"
)
`,
	},
	{
		name:       "import.32",
		pkg:        "fmt",
		renamedPkg: "f",
		in: `package main

// comment 1
import (
	f "fmt"
	/* comment 2 */ i "io"
)`,
		out: `package main

// comment 1
import (
	/* comment 2 */ i "io"
)
`,
	},
	{
		name:       "import.33",
		pkg:        "fmt",
		renamedPkg: "f",
		in: `package main

// comment 1
import (
	/* comment 2 */ f "fmt"
	i "io"
)`,
		out: `package main

// comment 1
import (
	i "io"
)
`,
	},
	{
		name:       "import.34",
		pkg:        "fmt",
		renamedPkg: "f",
		in: `package main

// comment 1
import (
	f "fmt" /* comment 2 */
	i "io"
)`,
		out: `package main

// comment 1
import (
	i "io"
)
`,
	},
	{
		name: "import.35",
		pkg:  "fmt",
		in: `package main

// comment 1
import (
	"fmt"
	// comment 2
	"io"
)`,
		out: `package main

// comment 1
import (
	// comment 2
	"io"
)
`,
	},
	{
		name: "import.36",
		pkg:  "fmt",
		in: `package main

/* comment 1 */
import (
	"fmt"
	/* comment 2 */
	"io"
)`,
		out: `package main

/* comment 1 */
import (
	/* comment 2 */
	"io"
)
`,
	},

	// Issue 20229: MergeLine panic on weird input
	{
		name: "import.37",
		pkg:  "io",
		in: `package main
import("_"
"io")`,
		out: `package main

import (
	"_"
)
`,
	},

	// Issue 28605: Delete specified import, even if that import path is imported under another name
	{
		name:       "import.38",
		renamedPkg: "",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	. "path"
	_ "path"
	pathpkg "path"
)
`,
	},
	{
		name:       "import.39",
		renamedPkg: "pathpkg",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	_ "path"
)
`,
	},
	{
		name:       "import.40",
		renamedPkg: "_",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	. "path"
	pathpkg "path"
)
`,
	},
	{
		name:       "import.41",
		renamedPkg: ".",
		pkg:        "path",
		in: `package main

import (
	"path"
	. "path"
	_ "path"
	pathpkg "path"
)
`,
		out: `package main

import (
	"path"
	_ "path"
	pathpkg "path"
)
`,
	},

	// Duplicate import declarations, all matching ones are deleted.
	{
		name:       "import.42",
		renamedPkg: "f",
		pkg:        "fmt",
		in: `package main

import "fmt"
import "fmt"
import f "fmt"
import f "fmt"
`,
		out: `package main

import "fmt"
import "fmt"
`,
	},
	{
		name:       "import.43",
		renamedPkg: "x",
		pkg:        "fmt",
		in: `package main

import "fmt"
import "fmt"
import f "fmt"
import f "fmt"
`,
		out: `package main

import "fmt"
import "fmt"
import f "fmt"
import f "fmt"
`,
		unchanged: true,
	},
	// this test panics without PositionFor in DeleteNamedImport
	{
		name:       "import.44",
		pkg:        "foo.com/other/v3",
		renamedPkg: "",
		in: `package main
//line mah.go:600

import (
"foo.com/a.thing"
"foo.com/surprise"
"foo.com/v1"
"foo.com/other/v2"
"foo.com/other/v3"
)
`,
		out: `package main

//line mah.go:600

import (
	"foo.com/a.thing"
	"foo.com/other/v2"
	"foo.com/surprise"
	"foo.com/v1"
)
`,
	},
}

func TestDeleteImport(t *testing.T) {
	for _, test := range deleteTests {
		file := parse(t, test.name, test.in)
		var before bytes.Buffer
		ast.Fprint(&before, fset, file, nil)
		deleted := DeleteNamedImport(fset, file, test.renamedPkg, test.pkg)
		if got := print(t, test.name, file); got != test.out {
			t.Errorf("first run: %s:\ngot: %s\nwant: %s", test.name, got, test.out)
			var after bytes.Buffer
			ast.Fprint(&after, fset, file, nil)
			t.Logf("AST before:\n%s\nAST after:\n%s\n", before.String(), after.String())
		}
		if got, want := deleted, !test.unchanged; got != want {
			t.Errorf("first run: %s: deleted = %v, want %v", test.name, got, want)
		}

		// DeleteNamedImport should be idempotent. Verify that by calling it again,
		// expecting no change to the AST, and the returned deleted value to always be false.
		deleted = DeleteNamedImport(fset, file, test.renamedPkg, test.pkg)
		if got := print(t, test.name, file); got != test.out {
			t.Errorf("second run: %s:\ngot: %s\nwant: %s", test.name, got, test.out)
		}
		if got, want := deleted, false; got != want {
			t.Errorf("second run: %s: deleted = %v, want %v", test.name, got, want)
		}
	}
}

func TestDeleteImportAfterAddImport(t *testing.T) {
	file := parse(t, "test", `package main

import "os"
`)
	if got, want := AddImport(fset, file, "fmt"), true; got != want {
		t.Errorf("AddImport: got: %v, want: %v", got, want)
	}
	if got, want := DeleteImport(fset, file, "fmt"), true; got != want {
		t.Errorf("DeleteImport: got: %v, want: %v", got, want)
	}
}

type rewriteTest struct {
	name   string
	srcPkg string
	dstPkg string
	in     string
	out    string
}

var rewriteTests = []rewriteTest{
	{
		name:   "import.13",
		srcPkg: "utf8",
		dstPkg: "encoding/utf8",
		in: `package main

import (
	"io"
	"os"
	"utf8" // thanks ken
)
`,
		out: `package main

import (
	"encoding/utf8" // thanks ken
	"io"
	"os"
)
`,
	},
	{
		name:   "import.14",
		srcPkg: "asn1",
		dstPkg: "encoding/asn1",
		in: `package main

import (
	"asn1"
	"crypto"
	"crypto/rsa"
	_ "crypto/sha1"
	"crypto/x509"
	"crypto/x509/pkix"
	"time"
)

var x = 1
`,
		out: `package main

import (
	"crypto"
	"crypto/rsa"
	_ "crypto/sha1"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/asn1"
	"time"
)

var x = 1
`,
	},
	{
		name:   "import.15",
		srcPkg: "url",
		dstPkg: "net/url",
		in: `package main

import (
	"bufio"
	"net"
	"path"
	"url"
)

var x = 1 // comment on x, not on url
`,
		out: `package main

import (
	"bufio"
	"net"
	"net/url"
	"path"
)

var x = 1 // comment on x, not on url
`,
	},
	{
		name:   "import.16",
		srcPkg: "http",
		dstPkg: "net/http",
		in: `package main

import (
	"flag"
	"http"
	"log"
	"text/template"
)

var addr = flag.String("addr", ":1718", "http service address") // Q=17, R=18
`,
		out: `package main

import (
	"flag"
	"log"
	"net/http"
	"text/template"
)

var addr = flag.String("addr", ":1718", "http service address") // Q=17, R=18
`,
	},
}

func TestRewriteImport(t *testing.T) {
	for _, test := range rewriteTests {
		file := parse(t, test.name, test.in)
		RewriteImport(fset, file, test.srcPkg, test.dstPkg)
		if got := print(t, test.name, file); got != test.out {
			t.Errorf("%s:\ngot: %s\nwant: %s", test.name, got, test.out)
		}
	}
}

var importsTests = []struct {
	name string
	in   string
	want [][]string
}{
	{
		name: "no packages",
		in: `package foo
`,
		want: nil,
	},
	{
		name: "one group",
		in: `package foo

import (
	"fmt"
	"testing"
)
`,
		want: [][]string{{"fmt", "testing"}},
	},
	{
		name: "four groups",
		in: `package foo

import "C"
import (
	"fmt"
	"testing"

	"appengine"

	"myproject/mylib1"
	"myproject/mylib2"
)
`,
		want: [][]string{
			{"C"},
			{"fmt", "testing"},
			{"appengine"},
			{"myproject/mylib1", "myproject/mylib2"},
		},
	},
	{
		name: "multiple factored groups",
		in: `package foo

import (
	"fmt"
	"testing"

	"appengine"
)
import (
	"reflect"

	"bytes"
)
`,
		want: [][]string{
			{"fmt", "testing"},
			{"appengine"},
			{"reflect"},
			{"bytes"},
		},
	},
}

func unquote(s string) string {
	res, err := strconv.Unquote(s)
	if err != nil {
		return "could_not_unquote"
	}
	return res
}

func TestImports(t *testing.T) {
	fset := token.NewFileSet()
	for _, test := range importsTests {
		f, err := parser.ParseFile(fset, "test.go", test.in, 0)
		if err != nil {
			t.Errorf("%s: %v", test.name, err)
			continue
		}
		var got [][]string
		for _, group := range Imports(fset, f) {
			var b []string
			for _, spec := range group {
				b = append(b, unquote(spec.Path.Value))
			}
			got = append(got, b)
		}
		if !reflect.DeepEqual(got, test.want) {
			t.Errorf("Imports(%s)=%v, want %v", test.name, got, test.want)
		}
	}
}

var usesImportTests = []struct {
	name string
	path string
	in   string
	want bool
}{
	{
		name: "no packages",
		path: "io",
		in: `package foo
`,
		want: false,
	},
	{
		name: "import.1",
		path: "io",
		in: `package foo

import "io"

var _ io.Writer
`,
		want: true,
	},
	{
		name: "import.2",
		path: "io",
		in: `package foo

import "io"
`,
		want: false,
	},
	{
		name: "import.3",
		path: "io",
		in: `package foo

import "io"

var io = 42
`,
		want: false,
	},
	{
		name: "import.4",
		path: "io",
		in: `package foo

import i "io"

var _ i.Writer
`,
		want: true,
	},
	{
		name: "import.5",
		path: "io",
		in: `package foo

import i "io"
`,
		want: false,
	},
	{
		name: "import.6",
		path: "io",
		in: `package foo

import i "io"

var i = 42
var io = 42
`,
		want: false,
	},
	{
		name: "import.7",
		path: "encoding/json",
		in: `package foo

import "encoding/json"

var _ json.Encoder
`,
		want: true,
	},
	{
		name: "import.8",
		path: "encoding/json",
		in: `package foo

import "encoding/json"
`,
		want: false,
	},
	{
		name: "import.9",
		path: "encoding/json",
		in: `package foo

import "encoding/json"

var json = 42
`,
		want: false,
	},
	{
		name: "import.10",
		path: "encoding/json",
		in: `package foo

import j "encoding/json"

var _ j.Encoder
`,
		want: true,
	},
	{
		name: "import.11",
		path: "encoding/json",
		in: `package foo

import j "encoding/json"
`,
		want: false,
	},
	{
		name: "import.12",
		path: "encoding/json",
		in: `package foo

import j "encoding/json"

var j = 42
var json = 42
`,
		want: false,
	},
	{
		name: "import.13",
		path: "io",
		in: `package foo

import _ "io"
`,
		want: true,
	},
	{
		name: "import.14",
		path: "io",
		in: `package foo

import . "io"
`,
		want: true,
	},
}

func TestUsesImport(t *testing.T) {
	fset := token.NewFileSet()
	for _, test := range usesImportTests {
		f, err := parser.ParseFile(fset, "test.go", test.in, 0)
		if err != nil {
			t.Errorf("%s: %v", test.name, err)
			continue
		}
		got := UsesImport(f, test.path)
		if got != test.want {
			t.Errorf("UsesImport(%s)=%v, want %v", test.name, got, test.want)
		}
	}
}


================================================
FILE: go/ast/astutil/rewrite.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"fmt"
	"go/ast"
	"reflect"
	"sort"
)

// An ApplyFunc is invoked by Apply for each node n, even if n is nil,
// before and/or after the node's children, using a Cursor describing
// the current node and providing operations on it.
//
// The return value of ApplyFunc controls the syntax tree traversal.
// See Apply for details.
type ApplyFunc func(*Cursor) bool

// Apply traverses a syntax tree recursively, starting with root,
// and calling pre and post for each node as described below.
// Apply returns the syntax tree, possibly modified.
//
// If pre is not nil, it is called for each node before the node's
// children are traversed (pre-order). If pre returns false, no
// children are traversed, and post is not called for that node.
//
// If post is not nil, and a prior call of pre didn't return false,
// post is called for each node after its children are traversed
// (post-order). If post returns false, traversal is terminated and
// Apply returns immediately.
//
// Only fields that refer to AST nodes are considered children;
// i.e., token.Pos, Scopes, Objects, and fields of basic types
// (strings, etc.) are ignored.
//
// Children are traversed in the order in which they appear in the
// respective node's struct definition. A package's files are
// traversed in the filenames' alphabetical order.
func Apply(root ast.Node, pre, post ApplyFunc) (result ast.Node) {
	parent := &struct{ ast.Node }{root}
	defer func() {
		if r := recover(); r != nil && r != abort {
			panic(r)
		}
		result = parent.Node
	}()
	a := &application{pre: pre, post: post}
	a.apply(parent, "Node", nil, root)
	return
}

var abort = new(int) // singleton, to signal termination of Apply

// A Cursor describes a node encountered during Apply.
// Information about the node and its parent is available
// from the Node, Parent, Name, and Index methods.
//
// If p is a variable of type and value of the current parent node
// c.Parent(), and f is the field identifier with name c.Name(),
// the following invariants hold:
//
//	p.f            == c.Node()  if c.Index() <  0
//	p.f[c.Index()] == c.Node()  if c.Index() >= 0
//
// The methods Replace, Delete, InsertBefore, and InsertAfter
// can be used to change the AST without disrupting Apply.
//
// This type is not to be confused with [inspector.Cursor] from
// package [golang.org/x/tools/go/ast/inspector], which provides
// stateless navigation of immutable syntax trees.
type Cursor struct {
	parent ast.Node
	name   string
	iter   *iterator // valid if non-nil
	node   ast.Node
}

// Node returns the current Node.
func (c *Cursor) Node() ast.Node { return c.node }

// Parent returns the parent of the current Node.
func (c *Cursor) Parent() ast.Node { return c.parent }

// Name returns the name of the parent Node field that contains the current Node.
// If the parent is a *ast.Package and the current Node is a *ast.File, Name returns
// the filename for the current Node.
func (c *Cursor) Name() string { return c.name }

// Index reports the index >= 0 of the current Node in the slice of Nodes that
// contains it, or a value < 0 if the current Node is not part of a slice.
// The index of the current node changes if InsertBefore is called while
// processing the current node.
func (c *Cursor) Index() int {
	if c.iter != nil {
		return c.iter.index
	}
	return -1
}

// field returns the current node's parent field value.
func (c *Cursor) field() reflect.Value {
	return reflect.Indirect(reflect.ValueOf(c.parent)).FieldByName(c.name)
}

// Replace replaces the current Node with n.
// The replacement node is not walked by Apply.
func (c *Cursor) Replace(n ast.Node) {
	if _, ok := c.node.(*ast.File); ok {
		file, ok := n.(*ast.File)
		if !ok {
			panic("attempt to replace *ast.File with non-*ast.File")
		}
		c.parent.(*ast.Package).Files[c.name] = file
		return
	}

	v := c.field()
	if i := c.Index(); i >= 0 {
		v = v.Index(i)
	}
	v.Set(reflect.ValueOf(n))
}

// Delete deletes the current Node from its containing slice.
// If the current Node is not part of a slice, Delete panics.
// As a special case, if the current node is a package file,
// Delete removes it from the package's Files map.
func (c *Cursor) Delete() {
	if _, ok := c.node.(*ast.File); ok {
		delete(c.parent.(*ast.Package).Files, c.name)
		return
	}

	i := c.Index()
	if i < 0 {
		panic("Delete node not contained in slice")
	}
	v := c.field()
	l := v.Len()
	reflect.Copy(v.Slice(i, l), v.Slice(i+1, l))
	v.Index(l - 1).Set(reflect.Zero(v.Type().Elem()))
	v.SetLen(l - 1)
	c.iter.step--
}

// InsertAfter inserts n after the current Node in its containing slice.
// If the current Node is not part of a slice, InsertAfter panics.
// Apply does not walk n.
func (c *Cursor) InsertAfter(n ast.Node) {
	i := c.Index()
	if i < 0 {
		panic("InsertAfter node not contained in slice")
	}
	v := c.field()
	v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
	l := v.Len()
	reflect.Copy(v.Slice(i+2, l), v.Slice(i+1, l))
	v.Index(i + 1).Set(reflect.ValueOf(n))
	c.iter.step++
}

// InsertBefore inserts n before the current Node in its containing slice.
// If the current Node is not part of a slice, InsertBefore panics.
// Apply will not walk n.
func (c *Cursor) InsertBefore(n ast.Node) {
	i := c.Index()
	if i < 0 {
		panic("InsertBefore node not contained in slice")
	}
	v := c.field()
	v.Set(reflect.Append(v, reflect.Zero(v.Type().Elem())))
	l := v.Len()
	reflect.Copy(v.Slice(i+1, l), v.Slice(i, l))
	v.Index(i).Set(reflect.ValueOf(n))
	c.iter.index++
}

// application carries all the shared data so we can pass it around cheaply.
type application struct {
	pre, post ApplyFunc
	cursor    Cursor
	iter      iterator
}

func (a *application) apply(parent ast.Node, name string, iter *iterator, n ast.Node) {
	// convert typed nil into untyped nil
	if v := reflect.ValueOf(n); v.Kind() == reflect.Pointer && v.IsNil() {
		n = nil
	}

	// avoid heap-allocating a new cursor for each apply call; reuse a.cursor instead
	saved := a.cursor
	a.cursor.parent = parent
	a.cursor.name = name
	a.cursor.iter = iter
	a.cursor.node = n

	if a.pre != nil && !a.pre(&a.cursor) {
		a.cursor = saved
		return
	}

	// walk children
	// (the order of the cases matches the order of the corresponding node types in go/ast)
	switch n := n.(type) {
	case nil:
		// nothing to do

	// Comments and fields
	case *ast.Comment:
		// nothing to do

	case *ast.CommentGroup:
		if n != nil {
			a.applyList(n, "List")
		}

	case *ast.Field:
		a.apply(n, "Doc", nil, n.Doc)
		a.applyList(n, "Names")
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Tag", nil, n.Tag)
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.FieldList:
		a.applyList(n, "List")

	// Expressions
	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
		// nothing to do

	case *ast.Ellipsis:
		a.apply(n, "Elt", nil, n.Elt)

	case *ast.FuncLit:
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Body", nil, n.Body)

	case *ast.CompositeLit:
		a.apply(n, "Type", nil, n.Type)
		a.applyList(n, "Elts")

	case *ast.ParenExpr:
		a.apply(n, "X", nil, n.X)

	case *ast.SelectorExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Sel", nil, n.Sel)

	case *ast.IndexExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Index", nil, n.Index)

	case *ast.IndexListExpr:
		a.apply(n, "X", nil, n.X)
		a.applyList(n, "Indices")

	case *ast.SliceExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Low", nil, n.Low)
		a.apply(n, "High", nil, n.High)
		a.apply(n, "Max", nil, n.Max)

	case *ast.TypeAssertExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Type", nil, n.Type)

	case *ast.CallExpr:
		a.apply(n, "Fun", nil, n.Fun)
		a.applyList(n, "Args")

	case *ast.StarExpr:
		a.apply(n, "X", nil, n.X)

	case *ast.UnaryExpr:
		a.apply(n, "X", nil, n.X)

	case *ast.BinaryExpr:
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Y", nil, n.Y)

	case *ast.KeyValueExpr:
		a.apply(n, "Key", nil, n.Key)
		a.apply(n, "Value", nil, n.Value)

	// Types
	case *ast.ArrayType:
		a.apply(n, "Len", nil, n.Len)
		a.apply(n, "Elt", nil, n.Elt)

	case *ast.StructType:
		a.apply(n, "Fields", nil, n.Fields)

	case *ast.FuncType:
		if tparams := n.TypeParams; tparams != nil {
			a.apply(n, "TypeParams", nil, tparams)
		}
		a.apply(n, "Params", nil, n.Params)
		a.apply(n, "Results", nil, n.Results)

	case *ast.InterfaceType:
		a.apply(n, "Methods", nil, n.Methods)

	case *ast.MapType:
		a.apply(n, "Key", nil, n.Key)
		a.apply(n, "Value", nil, n.Value)

	case *ast.ChanType:
		a.apply(n, "Value", nil, n.Value)

	// Statements
	case *ast.BadStmt:
		// nothing to do

	case *ast.DeclStmt:
		a.apply(n, "Decl", nil, n.Decl)

	case *ast.EmptyStmt:
		// nothing to do

	case *ast.LabeledStmt:
		a.apply(n, "Label", nil, n.Label)
		a.apply(n, "Stmt", nil, n.Stmt)

	case *ast.ExprStmt:
		a.apply(n, "X", nil, n.X)

	case *ast.SendStmt:
		a.apply(n, "Chan", nil, n.Chan)
		a.apply(n, "Value", nil, n.Value)

	case *ast.IncDecStmt:
		a.apply(n, "X", nil, n.X)

	case *ast.AssignStmt:
		a.applyList(n, "Lhs")
		a.applyList(n, "Rhs")

	case *ast.GoStmt:
		a.apply(n, "Call", nil, n.Call)

	case *ast.DeferStmt:
		a.apply(n, "Call", nil, n.Call)

	case *ast.ReturnStmt:
		a.applyList(n, "Results")

	case *ast.BranchStmt:
		a.apply(n, "Label", nil, n.Label)

	case *ast.BlockStmt:
		a.applyList(n, "List")

	case *ast.IfStmt:
		a.apply(n, "Init", nil, n.Init)
		a.apply(n, "Cond", nil, n.Cond)
		a.apply(n, "Body", nil, n.Body)
		a.apply(n, "Else", nil, n.Else)

	case *ast.CaseClause:
		a.applyList(n, "List")
		a.applyList(n, "Body")

	case *ast.SwitchStmt:
		a.apply(n, "Init", nil, n.Init)
		a.apply(n, "Tag", nil, n.Tag)
		a.apply(n, "Body", nil, n.Body)

	case *ast.TypeSwitchStmt:
		a.apply(n, "Init", nil, n.Init)
		a.apply(n, "Assign", nil, n.Assign)
		a.apply(n, "Body", nil, n.Body)

	case *ast.CommClause:
		a.apply(n, "Comm", nil, n.Comm)
		a.applyList(n, "Body")

	case *ast.SelectStmt:
		a.apply(n, "Body", nil, n.Body)

	case *ast.ForStmt:
		a.apply(n, "Init", nil, n.Init)
		a.apply(n, "Cond", nil, n.Cond)
		a.apply(n, "Post", nil, n.Post)
		a.apply(n, "Body", nil, n.Body)

	case *ast.RangeStmt:
		a.apply(n, "Key", nil, n.Key)
		a.apply(n, "Value", nil, n.Value)
		a.apply(n, "X", nil, n.X)
		a.apply(n, "Body", nil, n.Body)

	// Declarations
	case *ast.ImportSpec:
		a.apply(n, "Doc", nil, n.Doc)
		a.apply(n, "Name", nil, n.Name)
		a.apply(n, "Path", nil, n.Path)
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.ValueSpec:
		a.apply(n, "Doc", nil, n.Doc)
		a.applyList(n, "Names")
		a.apply(n, "Type", nil, n.Type)
		a.applyList(n, "Values")
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.TypeSpec:
		a.apply(n, "Doc", nil, n.Doc)
		a.apply(n, "Name", nil, n.Name)
		if tparams := n.TypeParams; tparams != nil {
			a.apply(n, "TypeParams", nil, tparams)
		}
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Comment", nil, n.Comment)

	case *ast.BadDecl:
		// nothing to do

	case *ast.GenDecl:
		a.apply(n, "Doc", nil, n.Doc)
		a.applyList(n, "Specs")

	case *ast.FuncDecl:
		a.apply(n, "Doc", nil, n.Doc)
		a.apply(n, "Recv", nil, n.Recv)
		a.apply(n, "Name", nil, n.Name)
		a.apply(n, "Type", nil, n.Type)
		a.apply(n, "Body", nil, n.Body)

	// Files and packages
	case *ast.File:
		a.apply(n, "Doc", nil, n.Doc)
		a.apply(n, "Name", nil, n.Name)
		a.applyList(n, "Decls")
		// Don't walk n.Comments; they have either been walked already if
		// they are Doc comments, or they can be easily walked explicitly.

	case *ast.Package:
		// collect and sort names for reproducible behavior
		var names []string
		for name := range n.Files {
			names = append(names, name)
		}
		sort.Strings(names)
		for _, name := range names {
			a.apply(n, name, nil, n.Files[name])
		}

	default:
		panic(fmt.Sprintf("Apply: unexpected node type %T", n))
	}

	if a.post != nil && !a.post(&a.cursor) {
		panic(abort)
	}

	a.cursor = saved
}

// An iterator controls iteration over a slice of nodes.
type iterator struct {
	index, step int
}

func (a *application) applyList(parent ast.Node, name string) {
	// avoid heap-allocating a new iterator for each applyList call; reuse a.iter instead
	saved := a.iter
	a.iter.index = 0
	for {
		// must reload parent.name each time, since cursor modifications might change it
		v := reflect.Indirect(reflect.ValueOf(parent)).FieldByName(name)
		if a.iter.index >= v.Len() {
			break
		}

		// element x may be nil in a bad AST - be cautious
		var x ast.Node
		if e := v.Index(a.iter.index); e.IsValid() {
			x = e.Interface().(ast.Node)
		}

		a.iter.step = 1
		a.apply(parent, name, &a.iter, x)
		a.iter.index += a.iter.step
	}
	a.iter = saved
}


================================================
FILE: go/ast/astutil/rewrite_test.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil_test

import (
	"bytes"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"testing"

	"golang.org/x/tools/go/ast/astutil"
)

type rewriteTest struct {
	name       string
	orig, want string
	pre, post  astutil.ApplyFunc
}

var rewriteTests = []rewriteTest{
	{name: "nop", orig: "package p\n", want: "package p\n"},

	{name: "replace",
		orig: `package p

var x int
`,
		want: `package p

var t T
`,
		post: func(c *astutil.Cursor) bool {
			if _, ok := c.Node().(*ast.ValueSpec); ok {
				c.Replace(valspec("t", "T"))
				return false
			}
			return true
		},
	},

	{name: "set doc strings",
		orig: `package p

const z = 0

type T struct{}

var x int
`,
		want: `package p
// a foo is a foo
const z = 0
// a foo is a foo
type T struct{}
// a foo is a foo
var x int
`,
		post: func(c *astutil.Cursor) bool {
			if _, ok := c.Parent().(*ast.GenDecl); ok && c.Name() == "Doc" && c.Node() == nil {
				c.Replace(&ast.CommentGroup{List: []*ast.Comment{{Text: "// a foo is a foo"}}})
			}
			return true
		},
	},

	{name: "insert names",
		orig: `package p

const a = 1
`,
		want: `package p

const a, b, c = 1, 2, 3
`,
		pre: func(c *astutil.Cursor) bool {
			if _, ok := c.Parent().(*ast.ValueSpec); ok {
				switch c.Name() {
				case "Names":
					c.InsertAfter(ast.NewIdent("c"))
					c.InsertAfter(ast.NewIdent("b"))
				case "Values":
					c.InsertAfter(&ast.BasicLit{Kind: token.INT, Value: "3"})
					c.InsertAfter(&ast.BasicLit{Kind: token.INT, Value: "2"})
				}
			}
			return true
		},
	},

	{name: "insert",
		orig: `package p

var (
	x int
	y int
)
`,
		want: `package p

var before1 int
var before2 int

var (
	x int
	y int
)
var after2 int
var after1 int
`,
		pre: func(c *astutil.Cursor) bool {
			if _, ok := c.Node().(*ast.GenDecl); ok {
				c.InsertBefore(vardecl("before1", "int"))
				c.InsertAfter(vardecl("after1", "int"))
				c.InsertAfter(vardecl("after2", "int"))
				c.InsertBefore(vardecl("before2", "int"))
			}
			return true
		},
	},

	{name: "delete",
		orig: `package p

var x int
var y int
var z int
`,
		want: `package p

var y int
var z int
`,
		pre: func(c *astutil.Cursor) bool {
			n := c.Node()
			if d, ok := n.(*ast.GenDecl); ok && d.Specs[0].(*ast.ValueSpec).Names[0].Name == "x" {
				c.Delete()
			}
			return true
		},
	},

	{name: "insertafter-delete",
		orig: `package p

var x int
var y int
var z int
`,
		want: `package p

var x1 int

var y int
var z int
`,
		pre: func(c *astutil.Cursor) bool {
			n := c.Node()
			if d, ok := n.(*ast.GenDecl); ok && d.Specs[0].(*ast.ValueSpec).Names[0].Name == "x" {
				c.InsertAfter(vardecl("x1", "int"))
				c.Delete()
			}
			return true
		},
	},

	{name: "delete-insertafter",
		orig: `package p

var x int
var y int
var z int
`,
		want: `package p

var y int
var x1 int
var z int
`,
		pre: func(c *astutil.Cursor) bool {
			n := c.Node()
			if d, ok := n.(*ast.GenDecl); ok && d.Specs[0].(*ast.ValueSpec).Names[0].Name == "x" {
				c.Delete()
				// The cursor is now effectively atop the 'var y int' node.
				c.InsertAfter(vardecl("x1", "int"))
			}
			return true
		},
	},
	{
		name: "replace",
		orig: `package p

type T[P1, P2 any] int

type R T[int, string]

func F[Q1 any](q Q1) {}
`,
		// TODO: note how the rewrite adds a trailing comma in "func F".
		// Is that a bug in the test, or in astutil.Apply?
		want: `package p

type S[R1, P2 any] int32

type R S[int32, string]

func F[X1 any](q X1,) {}
`,
		post: func(c *astutil.Cursor) bool {
			if ident, ok := c.Node().(*ast.Ident); ok {
				switch ident.Name {
				case "int":
					c.Replace(ast.NewIdent("int32"))
				case "T":
					c.Replace(ast.NewIdent("S"))
				case "P1":
					c.Replace(ast.NewIdent("R1"))
				case "Q1":
					c.Replace(ast.NewIdent("X1"))
				}
			}
			return true
		},
	},
}

func valspec(name, typ string) *ast.ValueSpec {
	return &ast.ValueSpec{Names: []*ast.Ident{ast.NewIdent(name)},
		Type: ast.NewIdent(typ),
	}
}

func vardecl(name, typ string) *ast.GenDecl {
	return &ast.GenDecl{
		Tok:   token.VAR,
		Specs: []ast.Spec{valspec(name, typ)},
	}
}

func TestRewrite(t *testing.T) {
	t.Run("*", func(t *testing.T) {
		for _, test := range rewriteTests {
			t.Run(test.name, func(t *testing.T) {
				t.Parallel()
				fset := token.NewFileSet()
				f, err := parser.ParseFile(fset, test.name, test.orig, parser.ParseComments)
				if err != nil {
					t.Fatal(err)
				}
				n := astutil.Apply(f, test.pre, test.post)
				var buf bytes.Buffer
				if err := format.Node(&buf, fset, n); err != nil {
					t.Fatal(err)
				}
				got := buf.String()
				if got != test.want {
					t.Errorf("got:\n\n%s\nwant:\n\n%s\n", got, test.want)
				}
			})
		}
	})
}

var sink ast.Node

func BenchmarkRewrite(b *testing.B) {
	for _, test := range rewriteTests {
		b.Run(test.name, func(b *testing.B) {
			for b.Loop() {
				b.StopTimer()
				fset := token.NewFileSet()
				f, err := parser.ParseFile(fset, test.name, test.orig, parser.ParseComments)
				if err != nil {
					b.Fatal(err)
				}
				b.StartTimer()
				sink = astutil.Apply(f, test.pre, test.post)
			}
		})
	}
}


================================================
FILE: go/ast/astutil/util.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import "go/ast"

// Unparen returns e with any enclosing parentheses stripped.
// Deprecated: use [ast.Unparen].
//
//go:fix inline
func Unparen(e ast.Expr) ast.Expr { return ast.Unparen(e) }


================================================
FILE: go/ast/edge/edge.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package edge defines identifiers for each field of an ast.Node
// struct type that refers to another Node.
package edge

import (
	"fmt"
	"go/ast"
	"reflect"
)

// A Kind describes a field of an ast.Node struct.
type Kind uint8

// String returns a description of the edge kind.
func (k Kind) String() string {
	if k == Invalid {
		return "<invalid>"
	}
	info := fieldInfos[k]
	return fmt.Sprintf("%v.%s", info.nodeType.Elem().Name(), info.name)
}

// NodeType returns the pointer-to-struct type of the ast.Node implementation.
func (k Kind) NodeType() reflect.Type { return fieldInfos[k].nodeType }

// FieldName returns the name of the field.
func (k Kind) FieldName() string { return fieldInfos[k].name }

// FieldType returns the declared type of the field.
func (k Kind) FieldType() reflect.Type { return fieldInfos[k].fieldType }

// Get returns the direct child of n identified by (k, idx).
// n's type must match k.NodeType().
// idx must be a valid slice index, or -1 for a non-slice.
func (k Kind) Get(n ast.Node, idx int) ast.Node {
	if k.NodeType() != reflect.TypeOf(n) {
		panic(fmt.Sprintf("%v.Get(%T): invalid node type", k, n))
	}
	v := reflect.ValueOf(n).Elem().Field(fieldInfos[k].index)
	if idx != -1 {
		v = v.Index(idx) // asserts valid index
	} else {
		// (The type assertion below asserts that v is not a slice.)
	}
	return v.Interface().(ast.Node) // may be nil
}

const (
	Invalid Kind = iota // for nodes at the root of the traversal

	// Kinds are sorted alphabetically.
	// Numbering is not stable.
	// Each is named Type_Field, where Type is the
	// ast.Node struct type and Field is the name of the field

	ArrayType_Elt
	ArrayType_Len
	AssignStmt_Lhs
	AssignStmt_Rhs
	BinaryExpr_X
	BinaryExpr_Y
	BlockStmt_List
	BranchStmt_Label
	CallExpr_Args
	CallExpr_Fun
	CaseClause_Body
	CaseClause_List
	ChanType_Value
	CommClause_Body
	CommClause_Comm
	CommentGroup_List
	CompositeLit_Elts
	CompositeLit_Type
	DeclStmt_Decl
	DeferStmt_Call
	Ellipsis_Elt
	ExprStmt_X
	FieldList_List
	Field_Comment
	Field_Doc
	Field_Names
	Field_Tag
	Field_Type
	File_Decls
	File_Doc
	File_Name
	ForStmt_Body
	ForStmt_Cond
	ForStmt_Init
	ForStmt_Post
	FuncDecl_Body
	FuncDecl_Doc
	FuncDecl_Name
	FuncDecl_Recv
	FuncDecl_Type
	FuncLit_Body
	FuncLit_Type
	FuncType_Params
	FuncType_Results
	FuncType_TypeParams
	GenDecl_Doc
	GenDecl_Specs
	GoStmt_Call
	IfStmt_Body
	IfStmt_Cond
	IfStmt_Else
	IfStmt_Init
	ImportSpec_Comment
	ImportSpec_Doc
	ImportSpec_Name
	ImportSpec_Path
	IncDecStmt_X
	IndexExpr_Index
	IndexExpr_X
	IndexListExpr_Indices
	IndexListExpr_X
	InterfaceType_Methods
	KeyValueExpr_Key
	KeyValueExpr_Value
	LabeledStmt_Label
	LabeledStmt_Stmt
	MapType_Key
	MapType_Value
	ParenExpr_X
	RangeStmt_Body
	RangeStmt_Key
	RangeStmt_Value
	RangeStmt_X
	ReturnStmt_Results
	SelectStmt_Body
	SelectorExpr_Sel
	SelectorExpr_X
	SendStmt_Chan
	SendStmt_Value
	SliceExpr_High
	SliceExpr_Low
	SliceExpr_Max
	SliceExpr_X
	StarExpr_X
	StructType_Fields
	SwitchStmt_Body
	SwitchStmt_Init
	SwitchStmt_Tag
	TypeAssertExpr_Type
	TypeAssertExpr_X
	TypeSpec_Comment
	TypeSpec_Doc
	TypeSpec_Name
	TypeSpec_Type
	TypeSpec_TypeParams
	TypeSwitchStmt_Assign
	TypeSwitchStmt_Body
	TypeSwitchStmt_Init
	UnaryExpr_X
	ValueSpec_Comment
	ValueSpec_Doc
	ValueSpec_Names
	ValueSpec_Type
	ValueSpec_Values

	maxKind
)

// Assert that the encoding fits in 7 bits,
// as the inspector relies on this.
// (We are currently at 104.)
var _ = [1 << 7]struct{}{}[maxKind]

type fieldInfo struct {
	nodeType  reflect.Type // pointer-to-struct type of ast.Node implementation
	name      string
	index     int
	fieldType reflect.Type
}

func info[N ast.Node](fieldName string) fieldInfo {
	nodePtrType := reflect.TypeFor[N]()
	f, ok := nodePtrType.Elem().FieldByName(fieldName)
	if !ok {
		panic(fieldName)
	}
	return fieldInfo{nodePtrType, fieldName, f.Index[0], f.Type}
}

var fieldInfos = [...]fieldInfo{
	Invalid:               {},
	ArrayType_Elt:         info[*ast.ArrayType]("Elt"),
	ArrayType_Len:         info[*ast.ArrayType]("Len"),
	AssignStmt_Lhs:        info[*ast.AssignStmt]("Lhs"),
	AssignStmt_Rhs:        info[*ast.AssignStmt]("Rhs"),
	BinaryExpr_X:          info[*ast.BinaryExpr]("X"),
	BinaryExpr_Y:          info[*ast.BinaryExpr]("Y"),
	BlockStmt_List:        info[*ast.BlockStmt]("List"),
	BranchStmt_Label:      info[*ast.BranchStmt]("Label"),
	CallExpr_Args:         info[*ast.CallExpr]("Args"),
	CallExpr_Fun:          info[*ast.CallExpr]("Fun"),
	CaseClause_Body:       info[*ast.CaseClause]("Body"),
	CaseClause_List:       info[*ast.CaseClause]("List"),
	ChanType_Value:        info[*ast.ChanType]("Value"),
	CommClause_Body:       info[*ast.CommClause]("Body"),
	CommClause_Comm:       info[*ast.CommClause]("Comm"),
	CommentGroup_List:     info[*ast.CommentGroup]("List"),
	CompositeLit_Elts:     info[*ast.CompositeLit]("Elts"),
	CompositeLit_Type:     info[*ast.CompositeLit]("Type"),
	DeclStmt_Decl:         info[*ast.DeclStmt]("Decl"),
	DeferStmt_Call:        info[*ast.DeferStmt]("Call"),
	Ellipsis_Elt:          info[*ast.Ellipsis]("Elt"),
	ExprStmt_X:            info[*ast.ExprStmt]("X"),
	FieldList_List:        info[*ast.FieldList]("List"),
	Field_Comment:         info[*ast.Field]("Comment"),
	Field_Doc:             info[*ast.Field]("Doc"),
	Field_Names:           info[*ast.Field]("Names"),
	Field_Tag:             info[*ast.Field]("Tag"),
	Field_Type:            info[*ast.Field]("Type"),
	File_Decls:            info[*ast.File]("Decls"),
	File_Doc:              info[*ast.File]("Doc"),
	File_Name:             info[*ast.File]("Name"),
	ForStmt_Body:          info[*ast.ForStmt]("Body"),
	ForStmt_Cond:          info[*ast.ForStmt]("Cond"),
	ForStmt_Init:          info[*ast.ForStmt]("Init"),
	ForStmt_Post:          info[*ast.ForStmt]("Post"),
	FuncDecl_Body:         info[*ast.FuncDecl]("Body"),
	FuncDecl_Doc:          info[*ast.FuncDecl]("Doc"),
	FuncDecl_Name:         info[*ast.FuncDecl]("Name"),
	FuncDecl_Recv:         info[*ast.FuncDecl]("Recv"),
	FuncDecl_Type:         info[*ast.FuncDecl]("Type"),
	FuncLit_Body:          info[*ast.FuncLit]("Body"),
	FuncLit_Type:          info[*ast.FuncLit]("Type"),
	FuncType_Params:       info[*ast.FuncType]("Params"),
	FuncType_Results:      info[*ast.FuncType]("Results"),
	FuncType_TypeParams:   info[*ast.FuncType]("TypeParams"),
	GenDecl_Doc:           info[*ast.GenDecl]("Doc"),
	GenDecl_Specs:         info[*ast.GenDecl]("Specs"),
	GoStmt_Call:           info[*ast.GoStmt]("Call"),
	IfStmt_Body:           info[*ast.IfStmt]("Body"),
	IfStmt_Cond:           info[*ast.IfStmt]("Cond"),
	IfStmt_Else:           info[*ast.IfStmt]("Else"),
	IfStmt_Init:           info[*ast.IfStmt]("Init"),
	ImportSpec_Comment:    info[*ast.ImportSpec]("Comment"),
	ImportSpec_Doc:        info[*ast.ImportSpec]("Doc"),
	ImportSpec_Name:       info[*ast.ImportSpec]("Name"),
	ImportSpec_Path:       info[*ast.ImportSpec]("Path"),
	IncDecStmt_X:          info[*ast.IncDecStmt]("X"),
	IndexExpr_Index:       info[*ast.IndexExpr]("Index"),
	IndexExpr_X:           info[*ast.IndexExpr]("X"),
	IndexListExpr_Indices: info[*ast.IndexListExpr]("Indices"),
	IndexListExpr_X:       info[*ast.IndexListExpr]("X"),
	InterfaceType_Methods: info[*ast.InterfaceType]("Methods"),
	KeyValueExpr_Key:      info[*ast.KeyValueExpr]("Key"),
	KeyValueExpr_Value:    info[*ast.KeyValueExpr]("Value"),
	LabeledStmt_Label:     info[*ast.LabeledStmt]("Label"),
	LabeledStmt_Stmt:      info[*ast.LabeledStmt]("Stmt"),
	MapType_Key:           info[*ast.MapType]("Key"),
	MapType_Value:         info[*ast.MapType]("Value"),
	ParenExpr_X:           info[*ast.ParenExpr]("X"),
	RangeStmt_Body:        info[*ast.RangeStmt]("Body"),
	RangeStmt_Key:         info[*ast.RangeStmt]("Key"),
	RangeStmt_Value:       info[*ast.RangeStmt]("Value"),
	RangeStmt_X:           info[*ast.RangeStmt]("X"),
	ReturnStmt_Results:    info[*ast.ReturnStmt]("Results"),
	SelectStmt_Body:       info[*ast.SelectStmt]("Body"),
	SelectorExpr_Sel:      info[*ast.SelectorExpr]("Sel"),
	SelectorExpr_X:        info[*ast.SelectorExpr]("X"),
	SendStmt_Chan:         info[*ast.SendStmt]("Chan"),
	SendStmt_Value:        info[*ast.SendStmt]("Value"),
	SliceExpr_High:        info[*ast.SliceExpr]("High"),
	SliceExpr_Low:         info[*ast.SliceExpr]("Low"),
	SliceExpr_Max:         info[*ast.SliceExpr]("Max"),
	SliceExpr_X:           info[*ast.SliceExpr]("X"),
	StarExpr_X:            info[*ast.StarExpr]("X"),
	StructType_Fields:     info[*ast.StructType]("Fields"),
	SwitchStmt_Body:       info[*ast.SwitchStmt]("Body"),
	SwitchStmt_Init:       info[*ast.SwitchStmt]("Init"),
	SwitchStmt_Tag:        info[*ast.SwitchStmt]("Tag"),
	TypeAssertExpr_Type:   info[*ast.TypeAssertExpr]("Type"),
	TypeAssertExpr_X:      info[*ast.TypeAssertExpr]("X"),
	TypeSpec_Comment:      info[*ast.TypeSpec]("Comment"),
	TypeSpec_Doc:          info[*ast.TypeSpec]("Doc"),
	TypeSpec_Name:         info[*ast.TypeSpec]("Name"),
	TypeSpec_Type:         info[*ast.TypeSpec]("Type"),
	TypeSpec_TypeParams:   info[*ast.TypeSpec]("TypeParams"),
	TypeSwitchStmt_Assign: info[*ast.TypeSwitchStmt]("Assign"),
	TypeSwitchStmt_Body:   info[*ast.TypeSwitchStmt]("Body"),
	TypeSwitchStmt_Init:   info[*ast.TypeSwitchStmt]("Init"),
	UnaryExpr_X:           info[*ast.UnaryExpr]("X"),
	ValueSpec_Comment:     info[*ast.ValueSpec]("Comment"),
	ValueSpec_Doc:         info[*ast.ValueSpec]("Doc"),
	ValueSpec_Names:       info[*ast.ValueSpec]("Names"),
	ValueSpec_Type:        info[*ast.ValueSpec]("Type"),
	ValueSpec_Values:      info[*ast.ValueSpec]("Values"),
}


================================================
FILE: go/ast/inspector/cursor.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector

import (
	"fmt"
	"go/ast"
	"go/token"
	"iter"
	"reflect"

	"golang.org/x/tools/go/ast/edge"
)

// A Cursor represents an [ast.Node]. It is immutable.
//
// Two Cursors compare equal if they represent the same node.
//
// The zero value of Cursor is not valid.
//
// Call [Inspector.Root] to obtain a cursor for the virtual root node
// of the traversal. This is the sole valid cursor for which [Cursor.Node]
// returns nil.
//
// Use the following methods to navigate efficiently around the tree:
//   - for ancestors, use [Cursor.Parent] and [Cursor.Enclosing];
//   - for children, use [Cursor.Child], [Cursor.Children],
//     [Cursor.FirstChild], and [Cursor.LastChild];
//   - for siblings, use [Cursor.PrevSibling] and [Cursor.NextSibling];
//   - for descendants, use [Cursor.FindByPos], [Cursor.FindNode],
//     [Cursor.Inspect], and [Cursor.Preorder].
//
// Use the [Cursor.ChildAt] and [Cursor.ParentEdge] methods for
// information about the edges in a tree: which field (and slice
// element) of the parent node holds the child.
type Cursor struct {
	in    *Inspector
	index int32 // index of push node; -1 for virtual root node
}

// Root returns a valid cursor for the virtual root node,
// whose children are the files provided to [New].
//
// Its [Cursor.Node] method return nil.
func (in *Inspector) Root() Cursor {
	return Cursor{in, -1}
}

// At returns the cursor at the specified index in the traversal,
// which must have been obtained from [Cursor.Index] on a Cursor
// belonging to the same Inspector (see [Cursor.Inspector]).
func (in *Inspector) At(index int32) Cursor {
	if index < 0 {
		panic("negative index")
	}
	if int(index) >= len(in.events) {
		panic("index out of range for this inspector")
	}
	if in.events[index].index < index {
		panic("invalid index") // (a push, not a pop)
	}
	return Cursor{in, index}
}

// Valid reports whether the cursor is valid.
// The zero value of cursor is invalid.
// Unless otherwise documented, it is not safe to call
// any other method on an invalid cursor.
func (c Cursor) Valid() bool {
	return c.in != nil
}

// Inspector returns the cursor's Inspector.
// It returns nil if the Cursor is not valid.
func (c Cursor) Inspector() *Inspector { return c.in }

// Index returns the index of this cursor position within the package.
//
// Clients should not assume anything about the numeric Index value
// except that it increases monotonically throughout the traversal.
// It is provided for use with [Inspector.At].
//
// Index must not be called on the Root node.
func (c Cursor) Index() int32 {
	if c.index < 0 {
		panic("Index called on Root node")
	}
	return c.index
}

// Node returns the node at the current cursor position,
// or nil for the cursor returned by [Inspector.Root].
func (c Cursor) Node() ast.Node {
	if c.index < 0 {
		return nil
	}
	return c.in.events[c.index].node
}

// String returns information about the cursor's node, if any.
func (c Cursor) String() string {
	if !c.Valid() {
		return "(invalid)"
	}
	if c.index < 0 {
		return "(root)"
	}
	return reflect.TypeOf(c.Node()).String()
}

// indices return the [start, end) half-open interval of event indices.
func (c Cursor) indices() (int32, int32) {
	if c.index < 0 {
		return 0, int32(len(c.in.events)) // root: all events
	} else {
		return c.index, c.in.events[c.index].index + 1 // just one subtree
	}
}

// Preorder returns an iterator over the nodes of the subtree
// represented by c in depth-first order. Each node in the sequence is
// represented by a Cursor that allows access to the Node, but may
// also be used to start a new traversal, or to obtain the stack of
// nodes enclosing the cursor.
//
// The traversal sequence is determined by [ast.Inspect]. The types
// argument, if non-empty, enables type-based filtering of events. The
// function f if is called only for nodes whose type matches an
// element of the types slice.
//
// If you need control over descent into subtrees,
// or need both pre- and post-order notifications, use [Cursor.Inspect]
func (c Cursor) Preorder(types ...ast.Node) iter.Seq[Cursor] {
	mask := maskOf(types)

	return func(yield func(Cursor) bool) {
		events := c.in.events

		for i, limit := c.indices(); i < limit; {
			ev := events[i]
			if ev.index > i { // push?
				if ev.typ&mask != 0 && !yield(Cursor{c.in, i}) {
					break
				}
				pop := ev.index
				if events[pop].typ&mask == 0 {
					// Subtree does not contain types: skip.
					i = pop + 1
					continue
				}
			}
			i++
		}
	}
}

// Inspect visits the nodes of the subtree represented by c in
// depth-first order. It calls f(n) for each node n before it
// visits n's children. If f returns true, Inspect invokes f
// recursively for each of the non-nil children of the node.
//
// Each node is represented by a Cursor that allows access to the
// Node, but may also be used to start a new traversal, or to obtain
// the stack of nodes enclosing the cursor.
//
// The complete traversal sequence is determined by [ast.Inspect].
// The types argument, if non-empty, enables type-based filtering of
// events. The function f if is called only for nodes whose type
// matches an element of the types slice.
func (c Cursor) Inspect(types []ast.Node, f func(c Cursor) (descend bool)) {
	mask := maskOf(types)
	events := c.in.events
	for i, limit := c.indices(); i < limit; {
		ev := events[i]
		if ev.index > i {
			// push
			pop := ev.index
			if ev.typ&mask != 0 && !f(Cursor{c.in, i}) ||
				events[pop].typ&mask == 0 {
				// The user opted not to descend, or the
				// subtree does not contain types:
				// skip past the pop.
				i = pop + 1
				continue
			}
		}
		i++
	}
}

// Enclosing returns an iterator over the nodes enclosing the current
// current node, starting with the Cursor itself.
//
// Enclosing must not be called on the Root node (whose [Cursor.Node] returns nil).
//
// The types argument, if non-empty, enables type-based filtering of
// events: the sequence includes only enclosing nodes whose type
// matches an element of the types slice.
func (c Cursor) Enclosing(types ...ast.Node) iter.Seq[Cursor] {
	if c.index < 0 {
		panic("Cursor.Enclosing called on Root node")
	}

	mask := maskOf(types)

	return func(yield func(Cursor) bool) {
		events := c.in.events
		for i := c.index; i >= 0; i = events[i].parent {
			if events[i].typ&mask != 0 && !yield(Cursor{c.in, i}) {
				break
			}
		}
	}
}

// Parent returns the parent of the current node.
//
// Parent must not be called on the Root node (whose [Cursor.Node] returns nil).
func (c Cursor) Parent() Cursor {
	if c.index < 0 {
		panic("Cursor.Parent called on Root node")
	}

	return Cursor{c.in, c.in.events[c.index].parent}
}

// ParentEdge returns the identity of the field in the parent node
// that holds this cursor's node, and if it is a list, the index within it.
//
// For example, f(x, y) is a CallExpr whose three children are Idents.
// f has edge kind [edge.CallExpr_Fun] and index -1.
// x and y have kind [edge.CallExpr_Args] and indices 0 and 1, respectively.
//
// If called on a child of the Root node, it returns ([edge.Invalid], -1).
//
// ParentEdge must not be called on the Root node (whose [Cursor.Node] returns nil).
func (c Cursor) ParentEdge() (edge.Kind, int) {
	if c.index < 0 {
		panic("Cursor.ParentEdge called on Root node")
	}
	events := c.in.events
	pop := events[c.index].index
	return unpackEdgeKindAndIndex(events[pop].parent)
}

// ParentEdgeKind returns the kind component of the result of [Cursor.ParentEdge].
func (c Cursor) ParentEdgeKind() edge.Kind {
	ek, _ := c.ParentEdge()
	return ek
}

// ParentEdgeIndex returns the index component of the result of [Cursor.ParentEdge].
func (c Cursor) ParentEdgeIndex() int {
	_, index := c.ParentEdge()
	return index
}

// ChildAt returns the cursor for the child of the
// current node identified by its edge and index.
// The index must be -1 if the edge.Kind is not a slice.
// The indicated child node must exist.
//
// ChildAt must not be called on the Root node (whose [Cursor.Node] returns nil).
//
// Invariant: c.Parent().ChildAt(c.ParentEdge()) == c.
func (c Cursor) ChildAt(k edge.Kind, idx int) Cursor {
	target := packEdgeKindAndIndex(k, idx)

	// Unfortunately there's no shortcut to looping.
	events := c.in.events
	i := c.index + 1
	for {
		pop := events[i].index
		if pop < i {
			break
		}
		if events[pop].parent == target {
			return Cursor{c.in, i}
		}
		i = pop + 1
	}
	panic(fmt.Sprintf("ChildAt(%v, %d): no such child of %v", k, idx, c))
}

// Child returns the cursor for n, which must be a direct child of c's Node.
//
// Child must not be called on the Root node (whose [Cursor.Node] returns nil).
func (c Cursor) Child(n ast.Node) Cursor {
	if c.index < 0 {
		panic("Cursor.Child called on Root node")
	}

	if false {
		// reference implementation
		for child := range c.Children() {
			if child.Node() == n {
				return child
			}
		}

	} else {
		// optimized implementation
		events := c.in.events
		for i := c.index + 1; events[i].index > i; i = events[i].index + 1 {
			if events[i].node == n {
				return Cursor{c.in, i}
			}
		}
	}
	panic(fmt.Sprintf("Child(%T): not a child of %v", n, c))
}

// NextSibling returns the cursor for the next sibling node in the same list
// (for example, of files, decls, specs, statements, fields, or expressions) as
// the current node. It returns (zero, false) if the node is the last node in
// the list, or is not part of a list.
//
// NextSibling must not be called on the Root node.
//
// See note at [Cursor.Children].
func (c Cursor) NextSibling() (Cursor, bool) {
	if c.index < 0 {
		panic("Cursor.NextSibling called on Root node")
	}

	events := c.in.events
	i := events[c.index].index + 1 // after corresponding pop
	if i < int32(len(events)) {
		if events[i].index > i { // push?
			return Cursor{c.in, i}, true
		}
	}
	return Cursor{}, false
}

// PrevSibling returns the cursor for the previous sibling node in the
// same list (for example, of files, decls, specs, statements, fields,
// or expressions) as the current node. It returns zero if the node is
// the first node in the list, or is not part of a list.
//
// It must not be called on the Root node.
//
// See note at [Cursor.Children].
func (c Cursor) PrevSibling() (Cursor, bool) {
	if c.index < 0 {
		panic("Cursor.PrevSibling called on Root node")
	}

	events := c.in.events
	i := c.index - 1
	if i >= 0 {
		if j := events[i].index; j < i { // pop?
			return Cursor{c.in, j}, true
		}
	}
	return Cursor{}, false
}

// FirstChild returns the first direct child of the current node,
// or zero if it has no children.
func (c Cursor) FirstChild() (Cursor, bool) {
	events := c.in.events
	i := c.index + 1                                   // i=0 if c is root
	if i < int32(len(events)) && events[i].index > i { // push?
		return Cursor{c.in, i}, true
	}
	return Cursor{}, false
}

// LastChild returns the last direct child of the current node,
// or zero if it has no children.
func (c Cursor) LastChild() (Cursor, bool) {
	events := c.in.events
	if c.index < 0 { // root?
		if len(events) > 0 {
			// return push of final event (a pop)
			return Cursor{c.in, events[len(events)-1].index}, true
		}
	} else {
		j := events[c.index].index - 1 // before corresponding pop
		// Inv: j == c.index if c has no children
		//  or  j is last child's pop.
		if j > c.index { // c has children
			return Cursor{c.in, events[j].index}, true
		}
	}
	return Cursor{}, false
}

// Children returns an iterator over the direct children of the
// current node, if any.
//
// When using Children, NextChild, and PrevChild, bear in mind that a
// Node's children may come from different fields, some of which may
// be lists of nodes without a distinguished intervening container
// such as [ast.BlockStmt].
//
// For example, [ast.CaseClause] has a field List of expressions and a
// field Body of statements, so the children of a CaseClause are a mix
// of expressions and statements. Other nodes that have "uncontained"
// list fields include:
//
//   - [ast.ValueSpec] (Names, Values)
//   - [ast.CompositeLit] (Type, Elts)
//   - [ast.IndexListExpr] (X, Indices)
//   - [ast.CallExpr] (Fun, Args)
//   - [ast.AssignStmt] (Lhs, Rhs)
//
// So, do not assume that the previous sibling of an ast.Stmt is also
// an ast.Stmt, or if it is, that they are executed sequentially,
// unless you have established that, say, its parent is a BlockStmt
// or its [Cursor.ParentEdge] is [edge.BlockStmt_List].
// For example, given "for S1; ; S2 {}", the predecessor of S2 is S1,
// even though they are not executed in sequence.
func (c Cursor) Children() iter.Seq[Cursor] {
	return func(yield func(Cursor) bool) {
		c, ok := c.FirstChild()
		for ok && yield(c) {
			c, ok = c.NextSibling()
		}
	}
}

// Contains reports whether c contains or is equal to c2.
//
// Both Cursors must belong to the same [Inspector];
// neither may be its Root node.
func (c Cursor) Contains(c2 Cursor) bool {
	if c.in != c2.in {
		panic("different inspectors")
	}
	events := c.in.events
	return c.index <= c2.index && events[c2.index].index <= events[c.index].index
}

// FindNode returns the cursor for node n if it belongs to the subtree
// rooted at c. It returns zero if n is not found.
func (c Cursor) FindNode(n ast.Node) (Cursor, bool) {

	// FindNode is equivalent to this code,
	// but more convenient and 15-20% faster:
	if false {
		for candidate := range c.Preorder(n) {
			if candidate.Node() == n {
				return candidate, true
			}
		}
		return Cursor{}, false
	}

	// TODO(adonovan): opt: should we assume Node.Pos is accurate
	// and combine type-based filtering with position filtering
	// like FindByPos?

	mask := maskOf([]ast.Node{n})
	events := c.in.events

	for i, limit := c.indices(); i < limit; i++ {
		ev := events[i]
		if ev.index > i { // push?
			if ev.typ&mask != 0 && ev.node == n {
				return Cursor{c.in, i}, true
			}
			pop := ev.index
			if events[pop].typ&mask == 0 {
				// Subtree does not contain type of n: skip.
				i = pop
			}
		}
	}
	return Cursor{}, false
}

// FindByPos returns the cursor for the innermost node n in the tree
// rooted at c such that n.Pos() <= start && end <= n.End().
// (For an *ast.File, it uses the bounds n.FileStart-n.FileEnd.)
//
// An empty range (start == end) between two adjacent nodes is
// considered to belong to the first node.
//
// It returns zero if none is found.
// Precondition: start <= end.
//
// See also [astutil.PathEnclosingInterval], which
// tolerates adjoining whitespace.
func (c Cursor) FindByPos(start, end token.Pos) (Cursor, bool) {
	if end < start {
		panic("end < start")
	}
	events := c.in.events

	// This algorithm could be implemented using c.Inspect,
	// but it is about 2.5x slower.

	// best is the push-index of the latest (=innermost) node containing range.
	// (Beware: latest is not always innermost because FuncDecl.{Name,Type} overlap.)
	best := int32(-1)
	for i, limit := c.indices(); i < limit; i++ {
		ev := events[i]
		if ev.index > i { // push?
			n := ev.node
			var nodeEnd token.Pos
			if file, ok := n.(*ast.File); ok {
				nodeEnd = file.FileEnd
				// Note: files may be out of Pos order.
				if file.FileStart > start {
					i = ev.index // disjoint, after; skip to next file
					continue
				}
			} else {
				// Edge case: FuncDecl.Name and .Type overlap:
				// Don't update best from Name to FuncDecl.Type.
				//
				// The condition can be read as:
				// - n is FuncType
				// - n.parent is FuncDecl
				// - best is strictly beneath the FuncDecl
				if ev.typ == 1<<nFuncType &&
					events[ev.parent].typ == 1<<nFuncDecl &&
					best > ev.parent {
					continue
				}

				nodeEnd = n.End()
				if n.Pos() > start {
					break // disjoint, after; stop
				}
			}

			// Inv: node.{Pos,FileStart} <= start
			if end <= nodeEnd {
				// node fully contains target range
				best = i

				// Don't search beyond end of the first match.
				// This is important only for an empty range (start=end)
				// between two adjoining nodes, which would otherwise
				// match both nodes; we want to match only the first.
				limit = ev.index
			} else if nodeEnd < start {
				i = ev.index // disjoint, before; skip forward
			}
		}
	}
	if best >= 0 {
		return Cursor{c.in, best}, true
	}
	return Cursor{}, false
}


================================================
FILE: go/ast/inspector/cursor_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"iter"
	"math/rand"
	"reflect"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
)

func TestCursor_Preorder(t *testing.T) {
	inspect := netInspect

	nodeFilter := []ast.Node{(*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)}

	// reference implementation
	var want []ast.Node
	for cur := range inspect.Root().Preorder(nodeFilter...) {
		want = append(want, cur.Node())
	}

	// Check entire sequence.
	got := slices.Collect(inspect.PreorderSeq(nodeFilter...))
	compare(t, got, want)

	// Check that break works.
	got = got[:0]
	for _, c := range firstN(10, inspect.Root().Preorder(nodeFilter...)) {
		got = append(got, c.Node())
	}
	compare(t, got, want[:10])
}

func TestCursor_nestedTraversal(t *testing.T) {
	const src = `package a
func f() {
	print("hello")
}
func g() {
	print("goodbye")
	panic("oops")
}
`
	fset := token.NewFileSet()
	f, _ := parser.ParseFile(fset, "a.go", src, 0)
	inspect := inspector.New([]*ast.File{f})

	var (
		funcDecls = []ast.Node{(*ast.FuncDecl)(nil)}
		callExprs = []ast.Node{(*ast.CallExpr)(nil)}
		nfuncs    = 0
		ncalls    = 0
	)

	for curFunc := range inspect.Root().Preorder(funcDecls...) {
		_ = curFunc.Node().(*ast.FuncDecl)

		// Check edge and index.
		if k, idx := curFunc.ParentEdge(); k != edge.File_Decls || idx != nfuncs {
			t.Errorf("%v.ParentEdge() = (%v, %d),  want edge.File_Decls, %d", curFunc, k, idx, nfuncs)
		}

		nfuncs++
		stack := slices.Collect(curFunc.Enclosing())

		// Stacks are convenient to print!
		if got, want := fmt.Sprint(stack), "[*ast.FuncDecl *ast.File]"; got != want {
			t.Errorf("curFunc.Enclosing() = %q, want %q", got, want)
		}

		// Parent, iterated, is Enclosing stack.
		i := 0
		for c := curFunc; c.Node() != nil; c = c.Parent() {
			if got, want := stack[i], c; got != want {
				t.Errorf("Enclosing[%d] = %v; Parent()^%d = %v", i, got, i, want)
			}
			i++
		}

		wantStack := "[*ast.CallExpr *ast.ExprStmt *ast.BlockStmt *ast.FuncDecl *ast.File]"

		// nested Preorder traversal
		preorderCount := 0
		for curCall := range curFunc.Preorder(callExprs...) {
			_ = curCall.Node().(*ast.CallExpr)
			preorderCount++
			stack := slices.Collect(curCall.Enclosing())
			if got := fmt.Sprint(stack); got != wantStack {
				t.Errorf("curCall.Enclosing() = %q, want %q", got, wantStack)
			}
		}

		// nested Inspect traversal
		inspectCount := 0
		curFunc.Inspect(callExprs, func(curCall inspector.Cursor) (proceed bool) {
			_ = curCall.Node().(*ast.CallExpr)
			inspectCount++
			stack := slices.Collect(curCall.Enclosing())
			if got := fmt.Sprint(stack); got != wantStack {
				t.Errorf("curCall.Enclosing() = %q, want %q", got, wantStack)
			}
			return true
		})

		if inspectCount != preorderCount {
			t.Errorf("Inspect (%d) and Preorder (%d) events are not consistent", inspectCount, preorderCount)
		}

		ncalls += preorderCount
	}

	if nfuncs != 2 {
		t.Errorf("Found %d FuncDecls, want 2", nfuncs)
	}
	if ncalls != 3 {
		t.Errorf("Found %d CallExprs, want 3", ncalls)
	}
}

func TestCursor_Children(t *testing.T) {
	inspect := netInspect

	// Assert that Cursor.Children agrees with
	// reference implementation for every node.
	var want, got []ast.Node
	for c := range inspect.Root().Preorder() {

		// reference implementation
		want = want[:0]
		{
			parent := c.Node()
			ast.Inspect(parent, func(n ast.Node) bool {
				if n != nil && n != parent {
					want = append(want, n)
				}
				return n == parent // descend only into parent
			})
		}

		// Check cursor-based implementation
		// (uses FirstChild+NextSibling).
		got = got[:0]
		for child := range c.Children() {
			got = append(got, child.Node())
		}

		if !slices.Equal(got, want) {
			t.Errorf("For %v\n"+
				"Using FirstChild+NextSibling: %v\n"+
				"Using ast.Inspect:            %v",
				c, sliceTypes(got), sliceTypes(want))
		}

		// Second cursor-based implementation
		// using LastChild+PrevSibling+reverse.
		got = got[:0]
		for c, ok := c.LastChild(); ok; c, ok = c.PrevSibling() {
			got = append(got, c.Node())
		}
		slices.Reverse(got)

		if !slices.Equal(got, want) {
			t.Errorf("For %v\n"+
				"Using LastChild+PrevSibling: %v\n"+
				"Using ast.Inspect:           %v",
				c, sliceTypes(got), sliceTypes(want))
		}
	}
}

func TestCursor_Inspect(t *testing.T) {
	inspect := netInspect

	// In all three loops, we'll gather both kinds of type switches,
	// but we'll prune the traversal from descending into (value) switches.
	switches := []ast.Node{(*ast.SwitchStmt)(nil), (*ast.TypeSwitchStmt)(nil)}

	// reference implementation (ast.Inspect)
	var nodesA []ast.Node
	for _, f := range netFiles {
		ast.Inspect(f, func(n ast.Node) (proceed bool) {
			switch n.(type) {
			case *ast.SwitchStmt, *ast.TypeSwitchStmt:
				nodesA = append(nodesA, n)
				return !is[*ast.SwitchStmt](n) // descend only into TypeSwitchStmt
			}
			return true
		})
	}

	// Test Cursor.Inspect implementation.
	var nodesB []ast.Node
	inspect.Root().Inspect(switches, func(c inspector.Cursor) (proceed bool) {
		n := c.Node()
		nodesB = append(nodesB, n)
		return !is[*ast.SwitchStmt](n) // descend only into TypeSwitchStmt
	})
	compare(t, nodesA, nodesB)

	// Test WithStack implementation.
	var nodesC []ast.Node
	inspect.WithStack(switches, func(n ast.Node, push bool, stack []ast.Node) (proceed bool) {
		if push {
			nodesC = append(nodesC, n)
			return !is[*ast.SwitchStmt](n) // descend only into TypeSwitchStmt
		}
		return false
	})
	compare(t, nodesA, nodesC)
}

func TestCursor_FindNode(t *testing.T) {
	inspect := netInspect

	// Enumerate all nodes of a particular type,
	// then check that FindByPos can find them,
	// starting at the root.
	//
	// (We use BasicLit because they are numerous.)
	root := inspect.Root()
	for c := range root.Preorder((*ast.BasicLit)(nil)) {
		node := c.Node()
		got, ok := root.FindNode(node)
		if !ok {
			t.Errorf("root.FindNode failed")
		} else if got != c {
			t.Errorf("root.FindNode returned %v, want %v", got, c)
		}
	}

	// Same thing, but searching only within subtrees (each FuncDecl).
	for funcDecl := range root.Preorder((*ast.FuncDecl)(nil)) {
		for c := range funcDecl.Preorder((*ast.BasicLit)(nil)) {
			node := c.Node()
			got, ok := funcDecl.FindNode(node)
			if !ok {
				t.Errorf("funcDecl.FindNode failed")
			} else if got != c {
				t.Errorf("funcDecl.FindNode returned %v, want %v", got, c)
			}

			// Also, check that we cannot find the BasicLit
			// beneath a different FuncDecl.
			if prevFunc, ok := funcDecl.PrevSibling(); ok {
				got, ok := prevFunc.FindNode(node)
				if ok {
					t.Errorf("prevFunc.FindNode succeeded unexpectedly: %v", got)
				}
			}
		}
	}
}

// TestCursor_FindByPos_order ensures that FindByPos does not assume files are in Pos order.
func TestCursor_FindByPos_order(t *testing.T) {
	// Pick an arbitrary decl.
	target := netFiles[7].Decls[0]

	// Find the target decl by its position.
	cur, ok := netInspect.Root().FindByPos(target.Pos(), target.End())
	if !ok || cur.Node() != target {
		t.Fatalf("unshuffled: FindByPos(%T) = (%v, %t)", target, cur, ok)
	}

	// Shuffle the files out of Pos order.
	files := slices.Clone(netFiles)
	rand.Shuffle(len(files), func(i, j int) {
		files[i], files[j] = files[j], files[i]
	})

	// Find it again.
	inspect := inspector.New(files)
	cur, ok = inspect.Root().FindByPos(target.Pos(), target.End())
	if !ok || cur.Node() != target {
		t.Fatalf("shuffled: FindByPos(%T) = (%v, %t)", target, cur, ok)
	}
}

func TestCursor_Edge(t *testing.T) {
	root := netInspect.Root()
	for cur := range root.Preorder() {
		if cur == root {
			continue // root node
		}

		var (
			parent = cur.Parent()
			e, idx = cur.ParentEdge()
		)

		// ast.File, child of root?
		if parent.Node() == nil {
			if e != edge.Invalid || idx != -1 {
				t.Errorf("%v.Edge = (%v, %d), want (Invalid, -1)", cur, e, idx)
			}
			continue
		}

		// Check Edge.NodeType matches type of Parent.Node.
		if e.NodeType() != reflect.TypeOf(parent.Node()) {
			t.Errorf("Edge.NodeType = %v, Parent.Node has type %T",
				e.NodeType(), parent.Node())
		}

		// Check c.Edge.Get(c.Parent.Node) == c.Node.
		if got := e.Get(parent.Node(), idx); got != cur.Node() {
			t.Errorf("cur=%v@%s: %s.Get(cur.Parent().Node(), %d) = %T@%s, want cur.Node()",
				cur, netFset.Position(cur.Node().Pos()), e, idx, got, netFset.Position(got.Pos()))
		}

		// Check c.Parent.ChildAt(c.ParentEdge()) == c.
		if got := parent.ChildAt(e, idx); got != cur {
			t.Errorf("cur=%v@%s: cur.Parent().ChildAt(%v, %d) = %T@%s, want cur",
				cur, netFset.Position(cur.Node().Pos()), e, idx, got.Node(), netFset.Position(got.Node().Pos()))
		}

		// Check that reflection on the parent finds the current node.
		fv := reflect.ValueOf(parent.Node()).Elem().FieldByName(e.FieldName())
		if idx >= 0 {
			fv = fv.Index(idx) // element of []ast.Node
		}
		if fv.Kind() == reflect.Interface {
			fv = fv.Elem() // e.g. ast.Expr -> *ast.Ident
		}
		got := fv.Interface().(ast.Node)
		if got != cur.Node() {
			t.Errorf("%v.Edge = (%v, %d); FieldName/Index reflection gave %T@%s, not original node",
				cur, e, idx, got, netFset.Position(got.Pos()))
		}

		// Check that Cursor.Child is the reverse of Parent.
		if cur.Parent().Child(cur.Node()) != cur {
			t.Errorf("Cursor.Parent.Child = %v, want %v", cur.Parent().Child(cur.Node()), cur)
		}

		// Check invariants of Contains:

		// A cursor contains itself.
		if !cur.Contains(cur) {
			t.Errorf("!cur.Contains(cur): %v", cur)
		}
		// A parent contains its child, but not the inverse.
		if !parent.Contains(cur) {
			t.Errorf("!cur.Parent().Contains(cur): %v", cur)
		}
		if cur.Contains(parent) {
			t.Errorf("cur.Contains(cur.Parent()): %v", cur)
		}
		// A grandparent contains its grandchild, but not the inverse.
		if grandparent := cur.Parent(); grandparent.Node() != nil {
			if !grandparent.Contains(cur) {
				t.Errorf("!cur.Parent().Parent().Contains(cur): %v", cur)
			}
			if cur.Contains(grandparent) {
				t.Errorf("cur.Contains(cur.Parent().Parent()): %v", cur)
			}
		}
		// A cursor and its uncle/aunt do not contain each other.
		if uncle, ok := parent.NextSibling(); ok {
			if uncle.Contains(cur) {
				t.Errorf("cur.Parent().NextSibling().Contains(cur): %v", cur)
			}
			if cur.Contains(uncle) {
				t.Errorf("cur.Contains(cur.Parent().NextSibling()): %v", cur)
			}
		}
	}
}

// Regression test for mutilple matching nodes in FindByPos (#76872).
func TestCursor_FindByPos_Boundary(t *testing.T) {
	// This test verifies that when a cursor position is on the boundary of two
	// adjacent nodes (e.g. "foo|("), FindByPos returns the first node
	// encountered in traversal order (which is usually the node "to the left").
	//
	// Note: The source is intentionally unformatted (no space between ')' and
	// '{') to ensure the nodes are strictly adjacent at the boundary.
	const src = `package p; func foo(a int){}`
	var (
		fset    = token.NewFileSet()
		f, _    = parser.ParseFile(fset, "p.go", src, 0)
		tokFile = fset.File(f.FileStart)
		inspect = inspector.New([]*ast.File{f})
	)

	d := f.Decls[0].(*ast.FuncDecl)

	format := func(pos token.Pos) string {
		off := tokFile.Offset(pos)
		return fmt.Sprintf("...%s<<>>%s...", src[off-1:off], src[off:off+1])
	}

	for _, test := range []struct {
		name string
		pos  token.Pos
		want ast.Node
	}{
		{
			// "foo|(" Ident
			pos:  d.Type.Params.Opening,
			want: d.Name,
		},
		{
			// ")|{" FieldList
			pos:  d.Body.Pos(),
			want: d.Type.Params,
		},
	} {
		cur, ok := inspect.Root().FindByPos(test.pos, test.pos)
		if !ok {
			t.Fatalf("FindByPos(%d) %s found nothing", test.pos, format(test.pos))
		}

		if cur.Node() != test.want {
			t.Errorf("FindByPos(%d) %s:\ngot  %T (%v)\nwant %T (%v)",
				test.pos, format(test.pos),
				cur.Node(), cur.Node(),
				test.want, test.want)
		}
	}
}

// Regression test for FuncDecl.Type irregularity in FindByPos (#75997).
func TestCursor_FindByPos(t *testing.T) {
	// Observe that the range of FuncType has a hole between
	// the "func" token and the start of Type.Params.
	// The hole contains FuncDecl.{Recv,Name}.
	//
	//                      ~~~~~~~~~~~~FuncDecl~~~~~~~~~~~~~~~~~~~~~~~~~
	//                           ~Recv~ ~Name~
	//                      ~~~~--------------~~~~FuncType~~~~~~
	//                                        ~Params~ ~Results~
	const src = `package a; func (recv) method(params) (results) { body }`
	var (
		fset    = token.NewFileSet()
		f, _    = parser.ParseFile(fset, "a.go", src, 0) // ignore parse errors
		tokFile = fset.File(f.FileStart)
		inspect = inspector.New([]*ast.File{f})
	)
	format := func(start, end token.Pos) string {
		var (
			startOffset = tokFile.Offset(start)
			endOffset   = tokFile.Offset(end)
		)
		return fmt.Sprintf("%s<<%s>>%s", src[:startOffset], src[startOffset:endOffset], src[endOffset:])
	}

	d := f.Decls[0].(*ast.FuncDecl)

	// Each test case specifies a [pos-end) range for
	// FindByPos and the syntax node it should find.
	for _, test := range []struct {
		start, end token.Pos
		want       ast.Node
	}{
		// pure subtrees
		{d.Pos(), d.End(), d},                // decl
		{d.Recv.Pos(), d.Recv.End(), d.Recv}, // recv
		{d.Name.Pos(), d.Name.End(), d.Name}, // name
		// (A FuncDecl can't have both Recv and TypeParams, so skip this one.)
		// {d.Type.TypeParams.Pos(), d.Type.TypeParams.End(), d.Type.TypeParams},
		{d.Type.Params.Pos(), d.Type.Params.End(), d.Type.Params},    // params
		{d.Type.Results.Pos(), d.Type.Results.End(), d.Type.Results}, // results
		{d.Body.Pos(), d.Body.End(), d.Body},                         // body

		// single tokens
		{
			// "func"
			d.Type.Func, d.Type.Func + 4,
			d, // arguably this should be d.Type
		},
		{
			// "(" FieldList
			d.Recv.Pos(), d.Recv.Pos() + 1,
			d.Recv,
		},
		{
			// "recv" Ident
			d.Recv.List[0].Pos(), d.Recv.List[0].Pos() + 1,
			d.Recv.List[0].Type,
		},
		{
			// "name" Ident
			d.Name.Pos(), d.Name.Pos() + 1,
			d.Name,
		},
		{
			// "(" FieldList
			d.Type.Params.Pos(), d.Type.Params.Pos() + 1,
			d.Type.Params,
		},
		{
			// "params" Ident
			d.Type.Params.List[0].Pos(), d.Type.Params.List[0].Pos() + 1,
			d.Type.Params.List[0].Type,
		},
		{
			// "(" FieldList
			d.Type.Results.Pos(), d.Type.Results.Pos() + 1,
			d.Type.Results,
		},
		{
			// "results" Ident
			d.Type.Results.List[0].Pos(), d.Type.Results.List[0].Pos() + 1,
			d.Type.Results.List[0].Type,
		},
		{
			// "{" BlockStmt
			d.Body.Pos(), d.Body.Pos() + 1,
			d.Body,
		},
		{
			// "body" Ident
			d.Body.List[0].Pos(), d.Body.List[0].Pos() + 1,
			d.Body.List[0].(*ast.ExprStmt).X,
		},
	} {
		cur, ok := inspect.Root().FindByPos(test.start, test.end)
		if !ok || cur.Node() == nil {
			t.Errorf("%s: FindByPos failed", format(test.start, test.end))
			continue
		}
		got := cur.Node()
		if got != test.want {
			t.Errorf("FindByPos:\ninput:\t%s\ngot:\t%s (%T)\nwant:\t%s (%T)",
				format(test.start, test.end),
				format(got.Pos(), got.End()), got,
				format(test.want.Pos(), test.want.End()), test.want)
		}
	}
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

// sliceTypes is a debugging helper that formats each slice element with %T.
func sliceTypes[T any](slice []T) string {
	var buf strings.Builder
	buf.WriteByte('[')
	for i, elem := range slice {
		if i > 0 {
			buf.WriteByte(' ')
		}
		fmt.Fprintf(&buf, "%T", elem)
	}
	buf.WriteByte(']')
	return buf.String()
}

func BenchmarkInspectCalls(b *testing.B) {
	inspect := netInspect

	// Measure marginal cost of traversal.

	callExprs := []ast.Node{(*ast.CallExpr)(nil)}

	b.Run("Preorder", func(b *testing.B) {
		var ncalls int
		for b.Loop() {
			inspect.Preorder(callExprs, func(n ast.Node) {
				_ = n.(*ast.CallExpr)
				ncalls++
			})
		}
	})

	b.Run("WithStack", func(b *testing.B) {
		var ncalls int
		for b.Loop() {
			inspect.WithStack(callExprs, func(n ast.Node, push bool, stack []ast.Node) (proceed bool) {
				_ = n.(*ast.CallExpr)
				if push {
					ncalls++
				}
				return true
			})
		}
	})

	b.Run("Cursor", func(b *testing.B) {
		var ncalls int
		for b.Loop() {
			for cur := range inspect.Root().Preorder(callExprs...) {
				_ = cur.Node().(*ast.CallExpr)
				ncalls++
			}
		}
	})

	b.Run("CursorEnclosing", func(b *testing.B) {
		var ncalls int
		for b.Loop() {
			for cur := range inspect.Root().Preorder(callExprs...) {
				_ = cur.Node().(*ast.CallExpr)
				for range cur.Enclosing() {
				}
				ncalls++
			}
		}
	})
}

// This benchmark compares methods for finding a known node in a tree.
func BenchmarkCursor_FindNode(b *testing.B) {
	root := netInspect.Root()

	callExprs := []ast.Node{(*ast.CallExpr)(nil)}

	// Choose a needle in the haystack to use as the search target:
	// a CallExpr not too near the start nor at too shallow a depth.
	var needle inspector.Cursor
	{
		count := 0
		found := false
		for c := range root.Preorder(callExprs...) {
			count++
			if count >= 1000 && iterlen(c.Enclosing()) >= 6 {
				needle = c
				found = true
				break
			}
		}
		if !found {
			b.Fatal("can't choose needle")
		}
	}

	b.ResetTimer()

	b.Run("Cursor.Preorder", func(b *testing.B) {
		needleNode := needle.Node()
		for b.Loop() {
			var found inspector.Cursor
			for c := range root.Preorder(callExprs...) {
				if c.Node() == needleNode {
					found = c
					break
				}
			}
			if found != needle {
				b.Errorf("Preorder search failed: got %v, want %v", found, needle)
			}
		}
	})

	// This method is about 10-15% faster than Cursor.Preorder.
	b.Run("Cursor.FindNode", func(b *testing.B) {
		for b.Loop() {
			found, ok := root.FindNode(needle.Node())
			if !ok || found != needle {
				b.Errorf("FindNode search failed: got %v, want %v", found, needle)
			}
		}
	})

	// This method is about 100x (!) faster than Cursor.Preorder.
	b.Run("Cursor.FindByPos", func(b *testing.B) {
		needleNode := needle.Node()
		for b.Loop() {
			found, ok := root.FindByPos(needleNode.Pos(), needleNode.End())
			if !ok || found != needle {
				b.Errorf("FindByPos search failed: got %v, want %v", found, needle)
			}
		}
	})
}

func iterlen[T any](seq iter.Seq[T]) (len int) {
	for range seq {
		len++
	}
	return
}


================================================
FILE: go/ast/inspector/inspector.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package inspector provides helper functions for traversal over the
// syntax trees of a package, including node filtering by type, and
// materialization of the traversal stack.
//
// During construction, the inspector does a complete traversal and
// builds a list of push/pop events and their node type. Subsequent
// method calls that request a traversal scan this list, rather than walk
// the AST, and perform type filtering using efficient bit sets.
// This representation is sometimes called a "balanced parenthesis tree."
//
// Experiments suggest the inspector's traversals are about 2.5x faster
// than [ast.Inspect], but it may take around 5 traversals for this
// benefit to amortize the inspector's construction cost.
// If efficiency is the primary concern, do not use Inspector for
// one-off traversals.
//
// The [Cursor] type provides a more flexible API for efficient
// navigation of syntax trees in all four "cardinal directions". For
// example, traversals may be nested, so you can find each node of
// type A and then search within it for nodes of type B. Or you can
// traverse from a node to its immediate neighbors: its parent, its
// previous and next sibling, or its first and last child. We
// recommend using methods of Cursor in preference to Inspector where
// possible.
package inspector

// There are four orthogonal features in a traversal:
//  1 type filtering
//  2 pruning
//  3 postorder calls to f
//  4 stack
// Rather than offer all of them in the API,
// only a few combinations are exposed:
// - Preorder is the fastest and has fewest features,
//   but is the most commonly needed traversal.
// - Nodes and WithStack both provide pruning and postorder calls,
//   even though few clients need it, because supporting two versions
//   is not justified.
// More combinations could be supported by expressing them as
// wrappers around a more generic traversal, but this was measured
// and found to degrade performance significantly (30%).

import (
	"go/ast"

	"golang.org/x/tools/go/ast/edge"
)

// An Inspector provides methods for inspecting
// (traversing) the syntax trees of a package.
type Inspector struct {
	events []event
}

func packEdgeKindAndIndex(ek edge.Kind, index int) int32 {
	return int32(uint32(index+1)<<7 | uint32(ek))
}

// unpackEdgeKindAndIndex unpacks the edge kind and edge index (within
// an []ast.Node slice) from the parent field of a pop event.
func unpackEdgeKindAndIndex(x int32) (edge.Kind, int) {
	// The "parent" field of a pop node holds the
	// edge Kind in the lower 7 bits and the index+1
	// in the upper 25.
	return edge.Kind(x & 0x7f), int(x>>7) - 1
}

// New returns an Inspector for the specified syntax trees.
func New(files []*ast.File) *Inspector {
	return &Inspector{traverse(files)}
}

// An event represents a push or a pop
// of an ast.Node during a traversal.
type event struct {
	node   ast.Node
	typ    uint64 // typeOf(node) on push event, or union of typ strictly between push and pop events on pop events
	index  int32  // index of corresponding push or pop event
	parent int32  // index of parent's push node (push nodes only), or packed edge kind/index (pop nodes only)
}

// TODO: Experiment with storing only the second word of event.node (unsafe.Pointer).
// Type can be recovered from the sole bit in typ.
// [Tried this, wasn't faster. --adonovan]

// Preorder visits all the nodes of the files supplied to [New] in
// depth-first order. It calls f(n) for each node n before it visits
// n's children.
//
// The complete traversal sequence is determined by [ast.Inspect].
// The types argument, if non-empty, enables type-based filtering of
// events. The function f is called only for nodes whose type
// matches an element of the types slice.
//
// The [Cursor.Preorder] method provides a richer alternative interface.
// Example:
//
//	for c := range in.Root().Preorder(types) { ... }
func (in *Inspector) Preorder(types []ast.Node, f func(ast.Node)) {
	// Because it avoids postorder calls to f, and the pruning
	// check, Preorder is almost twice as fast as Nodes. The two
	// features seem to contribute similar slowdowns (~1.4x each).

	// This function is equivalent to the PreorderSeq call below,
	// but to avoid the additional dynamic call (which adds 13-35%
	// to the benchmarks), we expand it out.
	//
	// in.PreorderSeq(types...)(func(n ast.Node) bool {
	// 	f(n)
	// 	return true
	// })

	mask := maskOf(types)
	for i := int32(0); i < int32(len(in.events)); {
		ev := in.events[i]
		if ev.index > i {
			// push
			if ev.typ&mask != 0 {
				f(ev.node)
			}
			pop := ev.index
			if in.events[pop].typ&mask == 0 {
				// Subtrees do not contain types: skip them and pop.
				i = pop + 1
				continue
			}
		}
		i++
	}
}

// Nodes visits the nodes of the files supplied to [New] in depth-first
// order. It calls f(n, true) for each node n before it visits n's
// children. If f returns true, Nodes invokes f recursively for each
// of the non-nil children of the node, followed by a call of
// f(n, false).
//
// The complete traversal sequence is determined by [ast.Inspect].
// The types argument, if non-empty, enables type-based filtering of
// events. The function f if is called only for nodes whose type
// matches an element of the types slice.
//
// The [Cursor.Inspect] method provides a richer alternative interface.
// Example:
//
//	in.Root().Inspect(types, func(c Cursor) bool {
//		...
//		return true
//	}
func (in *Inspector) Nodes(types []ast.Node, f func(n ast.Node, push bool) (proceed bool)) {
	mask := maskOf(types)
	for i := int32(0); i < int32(len(in.events)); {
		ev := in.events[i]
		if ev.index > i {
			// push
			pop := ev.index
			if ev.typ&mask != 0 {
				if !f(ev.node, true) {
					i = pop + 1 // jump to corresponding pop + 1
					continue
				}
			}
			if in.events[pop].typ&mask == 0 {
				// Subtrees do not contain types: skip them.
				i = pop
				continue
			}
		} else {
			// pop
			push := ev.index
			if in.events[push].typ&mask != 0 {
				f(ev.node, false)
			}
		}
		i++
	}
}

// WithStack visits nodes in a similar manner to Nodes, but it
// supplies each call to f an additional argument, the current
// traversal stack. The stack's first element is the outermost node,
// an *ast.File; its last is the innermost, n.
//
// The [Cursor.Inspect] method provides a richer alternative interface.
// Example:
//
//	in.Root().Inspect(types, func(c Cursor) bool {
//		stack := slices.Collect(c.Enclosing())
//		...
//		return true
//	})
func (in *Inspector) WithStack(types []ast.Node, f func(n ast.Node, push bool, stack []ast.Node) (proceed bool)) {
	mask := maskOf(types)
	var stack []ast.Node
	for i := int32(0); i < int32(len(in.events)); {
		ev := in.events[i]
		if ev.index > i {
			// push
			pop := ev.index
			stack = append(stack, ev.node)
			if ev.typ&mask != 0 {
				if !f(ev.node, true, stack) {
					i = pop + 1
					stack = stack[:len(stack)-1]
					continue
				}
			}
			if in.events[pop].typ&mask == 0 {
				// Subtrees does not contain types: skip them.
				i = pop
				continue
			}
		} else {
			// pop
			push := ev.index
			if in.events[push].typ&mask != 0 {
				f(ev.node, false, stack)
			}
			stack = stack[:len(stack)-1]
		}
		i++
	}
}

// traverse builds the table of events representing a traversal.
func traverse(files []*ast.File) []event {
	// Preallocate approximate number of events
	// based on source file extent of the declarations.
	// (We use End-Pos not FileStart-FileEnd to neglect
	// the effect of long doc comments.)
	// This makes traverse faster by 4x (!).
	var extent int
	for _, f := range files {
		extent += int(f.End() - f.Pos())
	}
	// This estimate is based on the net/http package.
	capacity := min(extent*33/100, 1e6) // impose some reasonable maximum (1M)

	v := &visitor{
		events: make([]event, 0, capacity),
		stack:  []item{{index: -1}}, // include an extra event so file nodes have a parent
	}
	for _, file := range files {
		walk(v, edge.Invalid, -1, file)
	}
	return v.events
}

type visitor struct {
	events []event
	stack  []item
}

type item struct {
	index            int32  // index of current node's push event
	parentIndex      int32  // index of parent node's push event
	typAccum         uint64 // accumulated type bits of current node's descendants
	edgeKindAndIndex int32  // edge.Kind and index, bit packed
}

func (v *visitor) push(ek edge.Kind, eindex int, node ast.Node) {
	var (
		index       = int32(len(v.events))
		parentIndex = v.stack[len(v.stack)-1].index
	)
	v.events = append(v.events, event{
		node:   node,
		parent: parentIndex,
		typ:    typeOf(node),
		index:  0, // (pop index is set later by visitor.pop)
	})
	v.stack = append(v.stack, item{
		index:            index,
		parentIndex:      parentIndex,
		edgeKindAndIndex: packEdgeKindAndIndex(ek, eindex),
	})

	// 2B nodes ought to be enough for anyone!
	if int32(len(v.events)) < 0 {
		panic("event index exceeded int32")
	}

	// 32M elements in an []ast.Node ought to be enough for anyone!
	if ek2, eindex2 := unpackEdgeKindAndIndex(packEdgeKindAndIndex(ek, eindex)); ek2 != ek || eindex2 != eindex {
		panic("Node slice index exceeded uint25")
	}
}

func (v *visitor) pop(node ast.Node) {
	top := len(v.stack) - 1
	current := v.stack[top]

	push := &v.events[current.index]
	parent := &v.stack[top-1]

	push.index = int32(len(v.events))              // make push event refer to pop
	parent.typAccum |= current.typAccum | push.typ // accumulate type bits into parent

	v.stack = v.stack[:top]

	v.events = append(v.events, event{
		node:   node,
		typ:    current.typAccum,
		index:  current.index,
		parent: current.edgeKindAndIndex, // see [unpackEdgeKindAndIndex]
	})
}


================================================
FILE: go/ast/inspector/inspector_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector_test

import (
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"log"
	"path/filepath"
	"reflect"
	"strconv"
	"strings"
	"testing"

	"golang.org/x/tools/go/ast/inspector"
)

// net/http package
var (
	netFset    = token.NewFileSet()
	netFiles   []*ast.File
	netInspect *inspector.Inspector
)

func init() {
	files, err := parseNetFiles()
	if err != nil {
		log.Fatal(err)
	}
	netFiles = files
	netInspect = inspector.New(netFiles)
}

func parseNetFiles() ([]*ast.File, error) {
	pkg, err := build.Default.Import("net", "", 0)
	if err != nil {
		return nil, err
	}
	var files []*ast.File
	for _, filename := range pkg.GoFiles {
		filename = filepath.Join(pkg.Dir, filename)
		f, err := parser.ParseFile(netFset, filename, nil, 0)
		if err != nil {
			return nil, err
		}
		files = append(files, f)
	}
	return files, nil
}

// TestInspectAllNodes compares Inspector against ast.Inspect.
func TestInspectAllNodes(t *testing.T) {
	inspect := inspector.New(netFiles)

	var nodesA []ast.Node
	inspect.Nodes(nil, func(n ast.Node, push bool) bool {
		if push {
			nodesA = append(nodesA, n)
		}
		return true
	})
	var nodesB []ast.Node
	for _, f := range netFiles {
		ast.Inspect(f, func(n ast.Node) bool {
			if n != nil {
				nodesB = append(nodesB, n)
			}
			return true
		})
	}
	compare(t, nodesA, nodesB)
}

func TestInspectGenericNodes(t *testing.T) {
	// src is using the 16 identifiers i0, i1, ... i15 so
	// we can easily verify that we've found all of them.
	const src = `package a

type I interface { ~i0|i1 }

type T[i2, i3 interface{ ~i4 }] struct {}

func f[i5, i6 any]() {
	_ = f[i7, i8]
	var x T[i9, i10]
}

func (*T[i11, i12]) m()

var _ i13[i14, i15]
`
	fset := token.NewFileSet()
	f, _ := parser.ParseFile(fset, "a.go", src, 0)
	inspect := inspector.New([]*ast.File{f})
	found := make([]bool, 16)

	indexListExprs := make(map[*ast.IndexListExpr]bool)

	// Verify that we reach all i* identifiers, and collect IndexListExpr nodes.
	inspect.Preorder(nil, func(n ast.Node) {
		switch n := n.(type) {
		case *ast.Ident:
			if n.Name[0] == 'i' {
				index, err := strconv.Atoi(n.Name[1:])
				if err != nil {
					t.Fatal(err)
				}
				found[index] = true
			}
		case *ast.IndexListExpr:
			indexListExprs[n] = false
		}
	})
	for i, v := range found {
		if !v {
			t.Errorf("missed identifier i%d", i)
		}
	}

	// Verify that we can filter to IndexListExprs that we found in the first
	// step.
	if len(indexListExprs) == 0 {
		t.Fatal("no index list exprs found")
	}
	inspect.Preorder([]ast.Node{&ast.IndexListExpr{}}, func(n ast.Node) {
		ix := n.(*ast.IndexListExpr)
		indexListExprs[ix] = true
	})
	for ix, v := range indexListExprs {
		if !v {
			t.Errorf("inspected node %v not filtered", ix)
		}
	}
}

// TestInspectPruning compares Inspector against ast.Inspect,
// pruning descent within ast.CallExpr nodes.
func TestInspectPruning(t *testing.T) {
	inspect := inspector.New(netFiles)

	var nodesA []ast.Node
	inspect.Nodes(nil, func(n ast.Node, push bool) bool {
		if push {
			nodesA = append(nodesA, n)
			_, isCall := n.(*ast.CallExpr)
			return !isCall // don't descend into function calls
		}
		return false
	})
	var nodesB []ast.Node
	for _, f := range netFiles {
		ast.Inspect(f, func(n ast.Node) bool {
			if n != nil {
				nodesB = append(nodesB, n)
				_, isCall := n.(*ast.CallExpr)
				return !isCall // don't descend into function calls
			}
			return false
		})
	}
	compare(t, nodesA, nodesB)
}

// compare calls t.Error if !slices.Equal(nodesA, nodesB).
func compare[N comparable](t *testing.T, nodesA, nodesB []N) {
	if len(nodesA) != len(nodesB) {
		t.Errorf("inconsistent node lists: %d vs %d", len(nodesA), len(nodesB))
	} else {
		for i := range nodesA {
			if a, b := nodesA[i], nodesB[i]; a != b {
				t.Errorf("node %d is inconsistent: %T, %T", i, a, b)
			}
		}
	}
}

func TestTypeFiltering(t *testing.T) {
	const src = `package a
func f() {
	print("hi")
	panic("oops")
}
`
	fset := token.NewFileSet()
	f, _ := parser.ParseFile(fset, "a.go", src, 0)
	inspect := inspector.New([]*ast.File{f})

	var got []string
	fn := func(n ast.Node, push bool) bool {
		if push {
			got = append(got, typeOf(n))
		}
		return true
	}

	// no type filtering
	inspect.Nodes(nil, fn)
	if want := strings.Fields("File Ident FuncDecl Ident FuncType FieldList BlockStmt ExprStmt CallExpr Ident BasicLit ExprStmt CallExpr Ident BasicLit"); !reflect.DeepEqual(got, want) {
		t.Errorf("inspect: got %s, want %s", got, want)
	}

	// type filtering
	nodeTypes := []ast.Node{
		(*ast.BasicLit)(nil),
		(*ast.CallExpr)(nil),
	}
	got = nil
	inspect.Nodes(nodeTypes, fn)
	if want := strings.Fields("CallExpr BasicLit CallExpr BasicLit"); !reflect.DeepEqual(got, want) {
		t.Errorf("inspect: got %s, want %s", got, want)
	}

	// inspect with stack
	got = nil
	inspect.WithStack(nodeTypes, func(n ast.Node, push bool, stack []ast.Node) bool {
		if push {
			var line []string
			for _, n := range stack {
				line = append(line, typeOf(n))
			}
			got = append(got, strings.Join(line, " "))
		}
		return true
	})
	want := []string{
		"File FuncDecl BlockStmt ExprStmt CallExpr",
		"File FuncDecl BlockStmt ExprStmt CallExpr BasicLit",
		"File FuncDecl BlockStmt ExprStmt CallExpr",
		"File FuncDecl BlockStmt ExprStmt CallExpr BasicLit",
	}
	if !reflect.DeepEqual(got, want) {
		t.Errorf("inspect: got %s, want %s", got, want)
	}
}

func typeOf(n ast.Node) string {
	return strings.TrimPrefix(reflect.TypeOf(n).String(), "*ast.")
}

// The numbers show a marginal improvement (ASTInspect/Inspect) of 3.5x,
// but a break-even point (NewInspector/(ASTInspect-Inspect)) of about 5
// traversals.
//
// BenchmarkASTInspect     1.0 ms
// BenchmarkNewInspector   2.2 ms
// BenchmarkInspect        0.39ms
// BenchmarkInspectFilter  0.01ms
// BenchmarkInspectCalls   0.14ms

func BenchmarkNewInspector(b *testing.B) {
	// Measure one-time construction overhead.
	for b.Loop() {
		inspector.New(netFiles)
	}
}

func BenchmarkInspect(b *testing.B) {

	inspect := inspector.New(netFiles)

	// Measure marginal cost of traversal.
	var ndecls, nlits int
	for b.Loop() {
		inspect.Preorder(nil, func(n ast.Node) {
			switch n.(type) {
			case *ast.FuncDecl:
				ndecls++
			case *ast.FuncLit:
				nlits++
			}
		})
	}
}

func BenchmarkInspectFilter(b *testing.B) {

	inspect := inspector.New(netFiles)

	// Measure marginal cost of traversal.
	nodeFilter := []ast.Node{(*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)}
	var ndecls, nlits int
	for b.Loop() {
		inspect.Preorder(nodeFilter, func(n ast.Node) {
			switch n.(type) {
			case *ast.FuncDecl:
				ndecls++
			case *ast.FuncLit:
				nlits++
			}
		})
	}
}

func BenchmarkASTInspect(b *testing.B) {
	var ndecls, nlits int
	for b.Loop() {
		for _, f := range netFiles {
			ast.Inspect(f, func(n ast.Node) bool {
				switch n.(type) {
				case *ast.FuncDecl:
					ndecls++
				case *ast.FuncLit:
					nlits++
				}
				return true
			})
		}
	}
}


================================================
FILE: go/ast/inspector/iter.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.23

package inspector

import (
	"go/ast"
	"iter"
)

// PreorderSeq returns an iterator that visits all the
// nodes of the files supplied to [New] in depth-first order.
// It visits each node n before n's children.
// The complete traversal sequence is determined by ast.Inspect.
//
// The types argument, if non-empty, enables type-based filtering:
// only nodes whose type matches an element of the types slice are
// included in the sequence.
//
// Example:
//
//	for call := range in.PreorderSeq((*ast.CallExpr)(nil)) { ... }
//
// The [All] function is more convenient if there is exactly one node type:
//
//	for call := range All[*ast.CallExpr](in) { ... }
//
// See also the newer and more flexible [Cursor] API, which lets you
// start the traversal at an arbitrary node, and reports each matching
// node by its Cursor, enabling easier navigation.
// The above example would be written thus:
//
//	for curCall := range in.Root().Preorder((*ast.CallExpr)(nil)) {
//		call := curCall.Node().(*ast.CallExpr)
//		...
//	}
func (in *Inspector) PreorderSeq(types ...ast.Node) iter.Seq[ast.Node] {

	// This implementation is identical to Preorder,
	// except that it supports breaking out of the loop.

	return func(yield func(ast.Node) bool) {
		mask := maskOf(types)
		for i := int32(0); i < int32(len(in.events)); {
			ev := in.events[i]
			if ev.index > i {
				// push
				if ev.typ&mask != 0 {
					if !yield(ev.node) {
						break
					}
				}
				pop := ev.index
				if in.events[pop].typ&mask == 0 {
					// Subtrees do not contain types: skip them and pop.
					i = pop + 1
					continue
				}
			}
			i++
		}
	}
}

// All[N] returns an iterator over all the nodes of type N.
// N must be a pointer-to-struct type that implements ast.Node.
//
// Example:
//
//	for call := range All[*ast.CallExpr](in) { ... }
//
// See also the newer and more flexible [Cursor] API, which lets you
// start the traversal at an arbitrary node, and reports each matching
// node by its Cursor, enabling easier navigation.
// The above example would be written thus:
//
//	for curCall := range in.Root().Preorder((*ast.CallExpr)(nil)) {
//		call := curCall.Node().(*ast.CallExpr)
//		...
//	}
func All[N interface {
	*S
	ast.Node
}, S any](in *Inspector) iter.Seq[N] {

	// To avoid additional dynamic call overheads,
	// we duplicate rather than call the logic of PreorderSeq.

	mask := typeOf((N)(nil))
	return func(yield func(N) bool) {
		for i := int32(0); i < int32(len(in.events)); {
			ev := in.events[i]
			if ev.index > i {
				// push
				if ev.typ&mask != 0 {
					if !yield(ev.node.(N)) {
						break
					}
				}
				pop := ev.index
				if in.events[pop].typ&mask == 0 {
					// Subtrees do not contain types: skip them and pop.
					i = pop + 1
					continue
				}
			}
			i++
		}
	}
}


================================================
FILE: go/ast/inspector/iter_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector_test

import (
	"go/ast"
	"iter"
	"slices"
	"testing"

	"golang.org/x/tools/go/ast/inspector"
)

// TestPreorderSeq checks PreorderSeq against Preorder.
func TestPreorderSeq(t *testing.T) {
	inspect := inspector.New(netFiles)

	nodeFilter := []ast.Node{(*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)}

	// reference implementation
	var want []ast.Node
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		want = append(want, n)
	})

	// Check entire sequence.
	got := slices.Collect(inspect.PreorderSeq(nodeFilter...))
	compare(t, got, want)

	// Check that break works.
	got = firstN(10, inspect.PreorderSeq(nodeFilter...))
	compare(t, got, want[:10])
}

// TestAll checks All against Preorder.
func TestAll(t *testing.T) {
	inspect := inspector.New(netFiles)

	// reference implementation
	var want []*ast.CallExpr
	inspect.Preorder([]ast.Node{(*ast.CallExpr)(nil)}, func(n ast.Node) {
		want = append(want, n.(*ast.CallExpr))
	})

	// Check entire sequence.
	got := slices.Collect(inspector.All[*ast.CallExpr](inspect))
	compare(t, got, want)

	// Check that break works.
	got = firstN(10, inspector.All[*ast.CallExpr](inspect))
	compare(t, got, want[:10])
}

// firstN(n, seq), returns a slice of up to n elements of seq.
func firstN[T any](n int, seq iter.Seq[T]) (res []T) {
	for x := range seq {
		res = append(res, x)
		if len(res) == n {
			break
		}
	}
	return res
}

// BenchmarkAllCalls is like BenchmarkInspectCalls,
// but using the single-type filtering iterator, All.
// (The iterator adds about 5-15%.)
func BenchmarkAllCalls(b *testing.B) {
	inspect := inspector.New(netFiles)

	// Measure marginal cost of traversal.
	var ncalls int
	for b.Loop() {
		for range inspector.All[*ast.CallExpr](inspect) {
			ncalls++
		}
	}
}


================================================
FILE: go/ast/inspector/typeof.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector

// This file defines func typeOf(ast.Node) uint64.
//
// The initial map-based implementation was too slow;
// see https://go-review.googlesource.com/c/tools/+/135655/1/go/ast/inspector/inspector.go#196

import (
	"go/ast"
	"math"
)

const (
	nArrayType = iota
	nAssignStmt
	nBadDecl
	nBadExpr
	nBadStmt
	nBasicLit
	nBinaryExpr
	nBlockStmt
	nBranchStmt
	nCallExpr
	nCaseClause
	nChanType
	nCommClause
	nComment
	nCommentGroup
	nCompositeLit
	nDeclStmt
	nDeferStmt
	nEllipsis
	nEmptyStmt
	nExprStmt
	nField
	nFieldList
	nFile
	nForStmt
	nFuncDecl
	nFuncLit
	nFuncType
	nGenDecl
	nGoStmt
	nIdent
	nIfStmt
	nImportSpec
	nIncDecStmt
	nIndexExpr
	nIndexListExpr
	nInterfaceType
	nKeyValueExpr
	nLabeledStmt
	nMapType
	nPackage
	nParenExpr
	nRangeStmt
	nReturnStmt
	nSelectStmt
	nSelectorExpr
	nSendStmt
	nSliceExpr
	nStarExpr
	nStructType
	nSwitchStmt
	nTypeAssertExpr
	nTypeSpec
	nTypeSwitchStmt
	nUnaryExpr
	nValueSpec
)

// typeOf returns a distinct single-bit value that represents the type of n.
//
// Various implementations were benchmarked with BenchmarkNewInspector:
//
//	                                                                GOGC=off
//	- type switch					4.9-5.5ms	2.1ms
//	- binary search over a sorted list of types	5.5-5.9ms	2.5ms
//	- linear scan, frequency-ordered list		5.9-6.1ms	2.7ms
//	- linear scan, unordered list			6.4ms		2.7ms
//	- hash table					6.5ms		3.1ms
//
// A perfect hash seemed like overkill.
//
// The compiler's switch statement is the clear winner
// as it produces a binary tree in code,
// with constant conditions and good branch prediction.
// (Sadly it is the most verbose in source code.)
// Binary search suffered from poor branch prediction.
func typeOf(n ast.Node) uint64 {
	// Fast path: nearly half of all nodes are identifiers.
	if _, ok := n.(*ast.Ident); ok {
		return 1 << nIdent
	}

	// These cases include all nodes encountered by ast.Inspect.
	switch n.(type) {
	case *ast.ArrayType:
		return 1 << nArrayType
	case *ast.AssignStmt:
		return 1 << nAssignStmt
	case *ast.BadDecl:
		return 1 << nBadDecl
	case *ast.BadExpr:
		return 1 << nBadExpr
	case *ast.BadStmt:
		return 1 << nBadStmt
	case *ast.BasicLit:
		return 1 << nBasicLit
	case *ast.BinaryExpr:
		return 1 << nBinaryExpr
	case *ast.BlockStmt:
		return 1 << nBlockStmt
	case *ast.BranchStmt:
		return 1 << nBranchStmt
	case *ast.CallExpr:
		return 1 << nCallExpr
	case *ast.CaseClause:
		return 1 << nCaseClause
	case *ast.ChanType:
		return 1 << nChanType
	case *ast.CommClause:
		return 1 << nCommClause
	case *ast.Comment:
		return 1 << nComment
	case *ast.CommentGroup:
		return 1 << nCommentGroup
	case *ast.CompositeLit:
		return 1 << nCompositeLit
	case *ast.DeclStmt:
		return 1 << nDeclStmt
	case *ast.DeferStmt:
		return 1 << nDeferStmt
	case *ast.Ellipsis:
		return 1 << nEllipsis
	case *ast.EmptyStmt:
		return 1 << nEmptyStmt
	case *ast.ExprStmt:
		return 1 << nExprStmt
	case *ast.Field:
		return 1 << nField
	case *ast.FieldList:
		return 1 << nFieldList
	case *ast.File:
		return 1 << nFile
	case *ast.ForStmt:
		return 1 << nForStmt
	case *ast.FuncDecl:
		return 1 << nFuncDecl
	case *ast.FuncLit:
		return 1 << nFuncLit
	case *ast.FuncType:
		return 1 << nFuncType
	case *ast.GenDecl:
		return 1 << nGenDecl
	case *ast.GoStmt:
		return 1 << nGoStmt
	case *ast.Ident:
		return 1 << nIdent
	case *ast.IfStmt:
		return 1 << nIfStmt
	case *ast.ImportSpec:
		return 1 << nImportSpec
	case *ast.IncDecStmt:
		return 1 << nIncDecStmt
	case *ast.IndexExpr:
		return 1 << nIndexExpr
	case *ast.IndexListExpr:
		return 1 << nIndexListExpr
	case *ast.InterfaceType:
		return 1 << nInterfaceType
	case *ast.KeyValueExpr:
		return 1 << nKeyValueExpr
	case *ast.LabeledStmt:
		return 1 << nLabeledStmt
	case *ast.MapType:
		return 1 << nMapType
	case *ast.Package:
		return 1 << nPackage
	case *ast.ParenExpr:
		return 1 << nParenExpr
	case *ast.RangeStmt:
		return 1 << nRangeStmt
	case *ast.ReturnStmt:
		return 1 << nReturnStmt
	case *ast.SelectStmt:
		return 1 << nSelectStmt
	case *ast.SelectorExpr:
		return 1 << nSelectorExpr
	case *ast.SendStmt:
		return 1 << nSendStmt
	case *ast.SliceExpr:
		return 1 << nSliceExpr
	case *ast.StarExpr:
		return 1 << nStarExpr
	case *ast.StructType:
		return 1 << nStructType
	case *ast.SwitchStmt:
		return 1 << nSwitchStmt
	case *ast.TypeAssertExpr:
		return 1 << nTypeAssertExpr
	case *ast.TypeSpec:
		return 1 << nTypeSpec
	case *ast.TypeSwitchStmt:
		return 1 << nTypeSwitchStmt
	case *ast.UnaryExpr:
		return 1 << nUnaryExpr
	case *ast.ValueSpec:
		return 1 << nValueSpec
	}
	return 0
}

func maskOf(nodes []ast.Node) uint64 {
	if len(nodes) == 0 {
		return math.MaxUint64 // match all node types
	}
	var mask uint64
	for _, n := range nodes {
		mask |= typeOf(n)
	}
	return mask
}


================================================
FILE: go/ast/inspector/walk.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inspector

// This file is a fork of ast.Inspect to reduce unnecessary dynamic
// calls and to gather edge information.
//
// Consistency with the original is ensured by TestInspectAllNodes.

import (
	"fmt"
	"go/ast"

	"golang.org/x/tools/go/ast/edge"
)

func walkList[N ast.Node](v *visitor, ek edge.Kind, list []N) {
	for i, node := range list {
		walk(v, ek, i, node)
	}
}

func walk(v *visitor, ek edge.Kind, index int, node ast.Node) {
	v.push(ek, index, node)

	// walk children
	// (the order of the cases matches the order
	// of the corresponding node types in ast.go)
	switch n := node.(type) {
	// Comments and fields
	case *ast.Comment:
		// nothing to do

	case *ast.CommentGroup:
		walkList(v, edge.CommentGroup_List, n.List)

	case *ast.Field:
		if n.Doc != nil {
			walk(v, edge.Field_Doc, -1, n.Doc)
		}
		walkList(v, edge.Field_Names, n.Names)
		if n.Type != nil {
			walk(v, edge.Field_Type, -1, n.Type)
		}
		if n.Tag != nil {
			walk(v, edge.Field_Tag, -1, n.Tag)
		}
		if n.Comment != nil {
			walk(v, edge.Field_Comment, -1, n.Comment)
		}

	case *ast.FieldList:
		walkList(v, edge.FieldList_List, n.List)

	// Expressions
	case *ast.BadExpr, *ast.Ident, *ast.BasicLit:
		// nothing to do

	case *ast.Ellipsis:
		if n.Elt != nil {
			walk(v, edge.Ellipsis_Elt, -1, n.Elt)
		}

	case *ast.FuncLit:
		walk(v, edge.FuncLit_Type, -1, n.Type)
		walk(v, edge.FuncLit_Body, -1, n.Body)

	case *ast.CompositeLit:
		if n.Type != nil {
			walk(v, edge.CompositeLit_Type, -1, n.Type)
		}
		walkList(v, edge.CompositeLit_Elts, n.Elts)

	case *ast.ParenExpr:
		walk(v, edge.ParenExpr_X, -1, n.X)

	case *ast.SelectorExpr:
		walk(v, edge.SelectorExpr_X, -1, n.X)
		walk(v, edge.SelectorExpr_Sel, -1, n.Sel)

	case *ast.IndexExpr:
		walk(v, edge.IndexExpr_X, -1, n.X)
		walk(v, edge.IndexExpr_Index, -1, n.Index)

	case *ast.IndexListExpr:
		walk(v, edge.IndexListExpr_X, -1, n.X)
		walkList(v, edge.IndexListExpr_Indices, n.Indices)

	case *ast.SliceExpr:
		walk(v, edge.SliceExpr_X, -1, n.X)
		if n.Low != nil {
			walk(v, edge.SliceExpr_Low, -1, n.Low)
		}
		if n.High != nil {
			walk(v, edge.SliceExpr_High, -1, n.High)
		}
		if n.Max != nil {
			walk(v, edge.SliceExpr_Max, -1, n.Max)
		}

	case *ast.TypeAssertExpr:
		walk(v, edge.TypeAssertExpr_X, -1, n.X)
		if n.Type != nil {
			walk(v, edge.TypeAssertExpr_Type, -1, n.Type)
		}

	case *ast.CallExpr:
		walk(v, edge.CallExpr_Fun, -1, n.Fun)
		walkList(v, edge.CallExpr_Args, n.Args)

	case *ast.StarExpr:
		walk(v, edge.StarExpr_X, -1, n.X)

	case *ast.UnaryExpr:
		walk(v, edge.UnaryExpr_X, -1, n.X)

	case *ast.BinaryExpr:
		walk(v, edge.BinaryExpr_X, -1, n.X)
		walk(v, edge.BinaryExpr_Y, -1, n.Y)

	case *ast.KeyValueExpr:
		walk(v, edge.KeyValueExpr_Key, -1, n.Key)
		walk(v, edge.KeyValueExpr_Value, -1, n.Value)

	// Types
	case *ast.ArrayType:
		if n.Len != nil {
			walk(v, edge.ArrayType_Len, -1, n.Len)
		}
		walk(v, edge.ArrayType_Elt, -1, n.Elt)

	case *ast.StructType:
		walk(v, edge.StructType_Fields, -1, n.Fields)

	case *ast.FuncType:
		if n.TypeParams != nil {
			walk(v, edge.FuncType_TypeParams, -1, n.TypeParams)
		}
		if n.Params != nil {
			walk(v, edge.FuncType_Params, -1, n.Params)
		}
		if n.Results != nil {
			walk(v, edge.FuncType_Results, -1, n.Results)
		}

	case *ast.InterfaceType:
		walk(v, edge.InterfaceType_Methods, -1, n.Methods)

	case *ast.MapType:
		walk(v, edge.MapType_Key, -1, n.Key)
		walk(v, edge.MapType_Value, -1, n.Value)

	case *ast.ChanType:
		walk(v, edge.ChanType_Value, -1, n.Value)

	// Statements
	case *ast.BadStmt:
		// nothing to do

	case *ast.DeclStmt:
		walk(v, edge.DeclStmt_Decl, -1, n.Decl)

	case *ast.EmptyStmt:
		// nothing to do

	case *ast.LabeledStmt:
		walk(v, edge.LabeledStmt_Label, -1, n.Label)
		walk(v, edge.LabeledStmt_Stmt, -1, n.Stmt)

	case *ast.ExprStmt:
		walk(v, edge.ExprStmt_X, -1, n.X)

	case *ast.SendStmt:
		walk(v, edge.SendStmt_Chan, -1, n.Chan)
		walk(v, edge.SendStmt_Value, -1, n.Value)

	case *ast.IncDecStmt:
		walk(v, edge.IncDecStmt_X, -1, n.X)

	case *ast.AssignStmt:
		walkList(v, edge.AssignStmt_Lhs, n.Lhs)
		walkList(v, edge.AssignStmt_Rhs, n.Rhs)

	case *ast.GoStmt:
		walk(v, edge.GoStmt_Call, -1, n.Call)

	case *ast.DeferStmt:
		walk(v, edge.DeferStmt_Call, -1, n.Call)

	case *ast.ReturnStmt:
		walkList(v, edge.ReturnStmt_Results, n.Results)

	case *ast.BranchStmt:
		if n.Label != nil {
			walk(v, edge.BranchStmt_Label, -1, n.Label)
		}

	case *ast.BlockStmt:
		walkList(v, edge.BlockStmt_List, n.List)

	case *ast.IfStmt:
		if n.Init != nil {
			walk(v, edge.IfStmt_Init, -1, n.Init)
		}
		walk(v, edge.IfStmt_Cond, -1, n.Cond)
		walk(v, edge.IfStmt_Body, -1, n.Body)
		if n.Else != nil {
			walk(v, edge.IfStmt_Else, -1, n.Else)
		}

	case *ast.CaseClause:
		walkList(v, edge.CaseClause_List, n.List)
		walkList(v, edge.CaseClause_Body, n.Body)

	case *ast.SwitchStmt:
		if n.Init != nil {
			walk(v, edge.SwitchStmt_Init, -1, n.Init)
		}
		if n.Tag != nil {
			walk(v, edge.SwitchStmt_Tag, -1, n.Tag)
		}
		walk(v, edge.SwitchStmt_Body, -1, n.Body)

	case *ast.TypeSwitchStmt:
		if n.Init != nil {
			walk(v, edge.TypeSwitchStmt_Init, -1, n.Init)
		}
		walk(v, edge.TypeSwitchStmt_Assign, -1, n.Assign)
		walk(v, edge.TypeSwitchStmt_Body, -1, n.Body)

	case *ast.CommClause:
		if n.Comm != nil {
			walk(v, edge.CommClause_Comm, -1, n.Comm)
		}
		walkList(v, edge.CommClause_Body, n.Body)

	case *ast.SelectStmt:
		walk(v, edge.SelectStmt_Body, -1, n.Body)

	case *ast.ForStmt:
		if n.Init != nil {
			walk(v, edge.ForStmt_Init, -1, n.Init)
		}
		if n.Cond != nil {
			walk(v, edge.ForStmt_Cond, -1, n.Cond)
		}
		if n.Post != nil {
			walk(v, edge.ForStmt_Post, -1, n.Post)
		}
		walk(v, edge.ForStmt_Body, -1, n.Body)

	case *ast.RangeStmt:
		if n.Key != nil {
			walk(v, edge.RangeStmt_Key, -1, n.Key)
		}
		if n.Value != nil {
			walk(v, edge.RangeStmt_Value, -1, n.Value)
		}
		walk(v, edge.RangeStmt_X, -1, n.X)
		walk(v, edge.RangeStmt_Body, -1, n.Body)

	// Declarations
	case *ast.ImportSpec:
		if n.Doc != nil {
			walk(v, edge.ImportSpec_Doc, -1, n.Doc)
		}
		if n.Name != nil {
			walk(v, edge.ImportSpec_Name, -1, n.Name)
		}
		walk(v, edge.ImportSpec_Path, -1, n.Path)
		if n.Comment != nil {
			walk(v, edge.ImportSpec_Comment, -1, n.Comment)
		}

	case *ast.ValueSpec:
		if n.Doc != nil {
			walk(v, edge.ValueSpec_Doc, -1, n.Doc)
		}
		walkList(v, edge.ValueSpec_Names, n.Names)
		if n.Type != nil {
			walk(v, edge.ValueSpec_Type, -1, n.Type)
		}
		walkList(v, edge.ValueSpec_Values, n.Values)
		if n.Comment != nil {
			walk(v, edge.ValueSpec_Comment, -1, n.Comment)
		}

	case *ast.TypeSpec:
		if n.Doc != nil {
			walk(v, edge.TypeSpec_Doc, -1, n.Doc)
		}
		walk(v, edge.TypeSpec_Name, -1, n.Name)
		if n.TypeParams != nil {
			walk(v, edge.TypeSpec_TypeParams, -1, n.TypeParams)
		}
		walk(v, edge.TypeSpec_Type, -1, n.Type)
		if n.Comment != nil {
			walk(v, edge.TypeSpec_Comment, -1, n.Comment)
		}

	case *ast.BadDecl:
		// nothing to do

	case *ast.GenDecl:
		if n.Doc != nil {
			walk(v, edge.GenDecl_Doc, -1, n.Doc)
		}
		walkList(v, edge.GenDecl_Specs, n.Specs)

	case *ast.FuncDecl:
		if n.Doc != nil {
			walk(v, edge.FuncDecl_Doc, -1, n.Doc)
		}
		if n.Recv != nil {
			walk(v, edge.FuncDecl_Recv, -1, n.Recv)
		}
		walk(v, edge.FuncDecl_Name, -1, n.Name)
		walk(v, edge.FuncDecl_Type, -1, n.Type)
		if n.Body != nil {
			walk(v, edge.FuncDecl_Body, -1, n.Body)
		}

	case *ast.File:
		if n.Doc != nil {
			walk(v, edge.File_Doc, -1, n.Doc)
		}
		walk(v, edge.File_Name, -1, n.Name)
		walkList(v, edge.File_Decls, n.Decls)
		// don't walk n.Comments - they have been
		// visited already through the individual
		// nodes

	default:
		// (includes *ast.Package)
		panic(fmt.Sprintf("Walk: unexpected node type %T", n))
	}

	v.pop(node)
}


================================================
FILE: go/buildutil/allpackages.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package buildutil provides utilities related to the go/build
// package in the standard library.
//
// All I/O is done via the build.Context file system interface, which must
// be concurrency-safe.
package buildutil // import "golang.org/x/tools/go/buildutil"

import (
	"go/build"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
)

// AllPackages returns the package path of each Go package in any source
// directory of the specified build context (e.g. $GOROOT or an element
// of $GOPATH).  Errors are ignored.  The results are sorted.
// All package paths are canonical, and thus may contain "/vendor/".
//
// The result may include import paths for directories that contain no
// *.go files, such as "archive" (in $GOROOT/src).
//
// All I/O is done via the build.Context file system interface,
// which must be concurrency-safe.
func AllPackages(ctxt *build.Context) []string {
	var list []string
	ForEachPackage(ctxt, func(pkg string, _ error) {
		list = append(list, pkg)
	})
	sort.Strings(list)
	return list
}

// ForEachPackage calls the found function with the package path of
// each Go package it finds in any source directory of the specified
// build context (e.g. $GOROOT or an element of $GOPATH).
// All package paths are canonical, and thus may contain "/vendor/".
//
// If the package directory exists but could not be read, the second
// argument to the found function provides the error.
//
// All I/O is done via the build.Context file system interface,
// which must be concurrency-safe.
func ForEachPackage(ctxt *build.Context, found func(importPath string, err error)) {
	ch := make(chan item)

	var wg sync.WaitGroup
	for _, root := range ctxt.SrcDirs() {
		wg.Add(1)
		go func() {
			allPackages(ctxt, root, ch)
			wg.Done()
		}()
	}
	go func() {
		wg.Wait()
		close(ch)
	}()

	// All calls to found occur in the caller's goroutine.
	for i := range ch {
		found(i.importPath, i.err)
	}
}

type item struct {
	importPath string
	err        error // (optional)
}

// We use a process-wide counting semaphore to limit
// the number of parallel calls to ReadDir.
var ioLimit = make(chan bool, 20)

func allPackages(ctxt *build.Context, root string, ch chan<- item) {
	root = filepath.Clean(root) + string(os.PathSeparator)

	var wg sync.WaitGroup

	var walkDir func(dir string)
	walkDir = func(dir string) {
		// Avoid .foo, _foo, and testdata directory trees.
		base := filepath.Base(dir)
		if base == "" || base[0] == '.' || base[0] == '_' || base == "testdata" {
			return
		}

		pkg := filepath.ToSlash(strings.TrimPrefix(dir, root))

		// Prune search if we encounter any of these import paths.
		switch pkg {
		case "builtin":
			return
		}

		ioLimit <- true
		files, err := ReadDir(ctxt, dir)
		<-ioLimit
		if pkg != "" || err != nil {
			ch <- item{pkg, err}
		}
		for _, fi := range files {
			if fi.IsDir() {
				wg.Add(1)
				go func() {
					walkDir(filepath.Join(dir, fi.Name()))
					wg.Done()
				}()
			}
		}
	}

	walkDir(root)
	wg.Wait()
}

// ExpandPatterns returns the set of packages matched by patterns,
// which may have the following forms:
//
//	golang.org/x/tools/cmd/guru     # a single package
//	golang.org/x/tools/...          # all packages beneath dir
//	...                             # the entire workspace.
//
// Order is significant: a pattern preceded by '-' removes matching
// packages from the set.  For example, these patterns match all encoding
// packages except encoding/xml:
//
//	encoding/... -encoding/xml
//
// A trailing slash in a pattern is ignored.  (Path components of Go
// package names are separated by slash, not the platform's path separator.)
func ExpandPatterns(ctxt *build.Context, patterns []string) map[string]bool {
	// TODO(adonovan): support other features of 'go list':
	// - "std"/"cmd"/"all" meta-packages
	// - "..." not at the end of a pattern
	// - relative patterns using "./" or "../" prefix

	pkgs := make(map[string]bool)
	doPkg := func(pkg string, neg bool) {
		if neg {
			delete(pkgs, pkg)
		} else {
			pkgs[pkg] = true
		}
	}

	// Scan entire workspace if wildcards are present.
	// TODO(adonovan): opt: scan only the necessary subtrees of the workspace.
	var all []string
	for _, arg := range patterns {
		if strings.HasSuffix(arg, "...") {
			all = AllPackages(ctxt)
			break
		}
	}

	for _, arg := range patterns {
		if arg == "" {
			continue
		}

		neg := arg[0] == '-'
		if neg {
			arg = arg[1:]
		}

		if arg == "..." {
			// ... matches all packages
			for _, pkg := range all {
				doPkg(pkg, neg)
			}
		} else if dir, ok := strings.CutSuffix(arg, "/..."); ok {
			// dir/... matches all packages beneath dir
			for _, pkg := range all {
				if strings.HasPrefix(pkg, dir) &&
					(len(pkg) == len(dir) || pkg[len(dir)] == '/') {
					doPkg(pkg, neg)
				}
			}
		} else {
			// single package
			doPkg(strings.TrimSuffix(arg, "/"), neg)
		}
	}

	return pkgs
}


================================================
FILE: go/buildutil/allpackages_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Incomplete source tree on Android.

//go:build !android

package buildutil_test

import (
	"go/build"
	"runtime"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/internal/packagestest"
)

func TestAllPackages(t *testing.T) {
	if runtime.Compiler == "gccgo" {
		t.Skip("gccgo has no standard packages")
	}

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{
		{Name: "golang.org/x/tools/go/buildutil", Files: packagestest.MustCopyFileTree(".")}})
	defer exported.Cleanup()

	var gopath string
	for _, env := range exported.Config.Env {
		if !strings.HasPrefix(env, "GOPATH=") {
			continue
		}
		gopath = strings.TrimPrefix(env, "GOPATH=")
	}
	if gopath == "" {
		t.Fatal("Failed to fish GOPATH out of env: ", exported.Config.Env)
	}

	var buildContext = build.Default
	buildContext.GOPATH = gopath
	all := buildutil.AllPackages(&buildContext)

	set := make(map[string]bool)
	for _, pkg := range all {
		set[pkg] = true
	}

	const wantAtLeast = 250
	if len(all) < wantAtLeast {
		t.Errorf("Found only %d packages, want at least %d", len(all), wantAtLeast)
	}

	for _, want := range []string{"fmt", "crypto/sha256", "golang.org/x/tools/go/buildutil"} {
		if !set[want] {
			t.Errorf("Package %q not found; got %s", want, all)
		}
	}
}

func TestExpandPatterns(t *testing.T) {
	tree := make(map[string]map[string]string)
	for _, pkg := range []string{
		"encoding",
		"encoding/xml",
		"encoding/hex",
		"encoding/json",
		"fmt",
	} {
		tree[pkg] = make(map[string]string)
	}
	ctxt := buildutil.FakeContext(tree)

	for _, test := range []struct {
		patterns string
		want     string
	}{
		{"", ""},
		{"fmt", "fmt"},
		{"nosuchpkg", "nosuchpkg"},
		{"nosuchdir/...", ""},
		{"...", "encoding encoding/hex encoding/json encoding/xml fmt"},
		{"encoding/... -encoding/xml", "encoding encoding/hex encoding/json"},
		{"... -encoding/...", "fmt"},
		{"encoding", "encoding"},
		{"encoding/", "encoding"},
	} {
		var pkgs []string
		for pkg := range buildutil.ExpandPatterns(ctxt, strings.Fields(test.patterns)) {
			pkgs = append(pkgs, pkg)
		}
		sort.Strings(pkgs)
		got := strings.Join(pkgs, " ")
		if got != test.want {
			t.Errorf("ExpandPatterns(%s) = %s, want %s",
				test.patterns, got, test.want)
		}
	}
}


================================================
FILE: go/buildutil/fakecontext.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil

import (
	"fmt"
	"go/build"
	"io"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strings"
	"time"
)

// FakeContext returns a build.Context for the fake file tree specified
// by pkgs, which maps package import paths to a mapping from file base
// names to contents.
//
// The fake Context has a GOROOT of "/go" and no GOPATH, and overrides
// the necessary file access methods to read from memory instead of the
// real file system.
//
// Unlike a real file tree, the fake one has only two levels---packages
// and files---so ReadDir("/go/src/") returns all packages under
// /go/src/ including, for instance, "math" and "math/big".
// ReadDir("/go/src/math/big") would return all the files in the
// "math/big" package.
func FakeContext(pkgs map[string]map[string]string) *build.Context {
	clean := func(filename string) string {
		f := path.Clean(filepath.ToSlash(filename))
		// Removing "/go/src" while respecting segment
		// boundaries has this unfortunate corner case:
		if f == "/go/src" {
			return ""
		}
		return strings.TrimPrefix(f, "/go/src/")
	}

	ctxt := build.Default // copy
	ctxt.GOROOT = "/go"
	ctxt.GOPATH = ""
	ctxt.Compiler = "gc"
	ctxt.IsDir = func(dir string) bool {
		dir = clean(dir)
		if dir == "" {
			return true // needed by (*build.Context).SrcDirs
		}
		return pkgs[dir] != nil
	}
	ctxt.ReadDir = func(dir string) ([]os.FileInfo, error) {
		dir = clean(dir)
		var fis []os.FileInfo
		if dir == "" {
			// enumerate packages
			for importPath := range pkgs {
				fis = append(fis, fakeDirInfo(importPath))
			}
		} else {
			// enumerate files of package
			for basename := range pkgs[dir] {
				fis = append(fis, fakeFileInfo(basename))
			}
		}
		sort.Sort(byName(fis))
		return fis, nil
	}
	ctxt.OpenFile = func(filename string) (io.ReadCloser, error) {
		filename = clean(filename)
		dir, base := path.Split(filename)
		content, ok := pkgs[path.Clean(dir)][base]
		if !ok {
			return nil, fmt.Errorf("file not found: %s", filename)
		}
		return io.NopCloser(strings.NewReader(content)), nil
	}
	ctxt.IsAbsPath = func(path string) bool {
		path = filepath.ToSlash(path)
		// Don't rely on the default (filepath.Path) since on
		// Windows, it reports virtual paths as non-absolute.
		return strings.HasPrefix(path, "/")
	}
	return &ctxt
}

type byName []os.FileInfo

func (s byName) Len() int           { return len(s) }
func (s byName) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
func (s byName) Less(i, j int) bool { return s[i].Name() < s[j].Name() }

type fakeFileInfo string

func (fi fakeFileInfo) Name() string    { return string(fi) }
func (fakeFileInfo) Sys() any           { return nil }
func (fakeFileInfo) ModTime() time.Time { return time.Time{} }
func (fakeFileInfo) IsDir() bool        { return false }
func (fakeFileInfo) Size() int64        { return 0 }
func (fakeFileInfo) Mode() os.FileMode  { return 0644 }

type fakeDirInfo string

func (fd fakeDirInfo) Name() string    { return string(fd) }
func (fakeDirInfo) Sys() any           { return nil }
func (fakeDirInfo) ModTime() time.Time { return time.Time{} }
func (fakeDirInfo) IsDir() bool        { return true }
func (fakeDirInfo) Size() int64        { return 0 }
func (fakeDirInfo) Mode() os.FileMode  { return 0755 }


================================================
FILE: go/buildutil/overlay.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil

import (
	"bufio"
	"bytes"
	"fmt"
	"go/build"
	"io"
	"path/filepath"
	"strconv"
	"strings"
)

// OverlayContext overlays a build.Context with additional files from
// a map. Files in the map take precedence over other files.
//
// In addition to plain string comparison, two file names are
// considered equal if their base names match and their directory
// components point at the same directory on the file system. That is,
// symbolic links are followed for directories, but not files.
//
// A common use case for OverlayContext is to allow editors to pass in
// a set of unsaved, modified files.
//
// Currently, only the Context.OpenFile function will respect the
// overlay. This may change in the future.
func OverlayContext(orig *build.Context, overlay map[string][]byte) *build.Context {
	// TODO(dominikh): Implement IsDir, HasSubdir and ReadDir

	rc := func(data []byte) (io.ReadCloser, error) {
		return io.NopCloser(bytes.NewBuffer(data)), nil
	}

	copy := *orig // make a copy
	ctxt := &copy
	ctxt.OpenFile = func(path string) (io.ReadCloser, error) {
		// Fast path: names match exactly.
		if content, ok := overlay[path]; ok {
			return rc(content)
		}

		// Slow path: check for same file under a different
		// alias, perhaps due to a symbolic link.
		for filename, content := range overlay {
			if sameFile(path, filename) {
				return rc(content)
			}
		}

		return OpenFile(orig, path)
	}
	return ctxt
}

// ParseOverlayArchive parses an archive containing Go files and their
// contents. The result is intended to be used with OverlayContext.
//
// # Archive format
//
// The archive consists of a series of files. Each file consists of a
// name, a decimal file size and the file contents, separated by
// newlines. No newline follows after the file contents.
func ParseOverlayArchive(archive io.Reader) (map[string][]byte, error) {
	overlay := make(map[string][]byte)
	r := bufio.NewReader(archive)
	for {
		// Read file name.
		filename, err := r.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				break // OK
			}
			return nil, fmt.Errorf("reading archive file name: %v", err)
		}
		filename = filepath.Clean(strings.TrimSpace(filename))

		// Read file size.
		sz, err := r.ReadString('\n')
		if err != nil {
			return nil, fmt.Errorf("reading size of archive file %s: %v", filename, err)
		}
		sz = strings.TrimSpace(sz)
		size, err := strconv.ParseUint(sz, 10, 32)
		if err != nil {
			return nil, fmt.Errorf("parsing size of archive file %s: %v", filename, err)
		}

		// Read file content.
		content := make([]byte, size)
		if _, err := io.ReadFull(r, content); err != nil {
			return nil, fmt.Errorf("reading archive file %s: %v", filename, err)
		}
		overlay[filename] = content
	}

	return overlay, nil
}


================================================
FILE: go/buildutil/overlay_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil_test

import (
	"go/build"
	"io"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
)

func TestParseOverlayArchive(t *testing.T) {
	var tt = []struct {
		in     string
		out    map[string][]byte
		hasErr bool
	}{
		{
			"a.go\n5\n12345",
			map[string][]byte{"a.go": []byte("12345")},
			false,
		},
		{
			"a.go\n5\n1234",
			nil,
			true,
		},
		{
			"a.go\n5\n12345b.go\n4\n1234",
			map[string][]byte{"a.go": []byte("12345"), "b.go": []byte("1234")},
			false,
		},
	}

	for _, test := range tt {
		got, err := buildutil.ParseOverlayArchive(strings.NewReader(test.in))
		if err == nil && test.hasErr {
			t.Errorf("expected error for %q", test.in)
		}
		if err != nil && !test.hasErr {
			t.Errorf("unexpected error %v for %q", err, test.in)
		}
		if !reflect.DeepEqual(got, test.out) {
			t.Errorf("got %#v, want %#v", got, test.out)
		}
	}
}

func TestOverlay(t *testing.T) {
	ctx := &build.Default
	ov := map[string][]byte{
		"/somewhere/a.go": []byte("file contents"),
	}
	names := []string{"/somewhere/a.go", "/somewhere//a.go"}
	ctx = buildutil.OverlayContext(ctx, ov)
	for _, name := range names {
		f, err := buildutil.OpenFile(ctx, name)
		if err != nil {
			t.Errorf("unexpected error %v", err)
		}
		b, err := io.ReadAll(f)
		if err != nil {
			t.Errorf("unexpected error %v", err)
		}
		if got, expected := string(b), string(ov["/somewhere/a.go"]); got != expected {
			t.Errorf("read %q, expected %q", got, expected)
		}
	}
}


================================================
FILE: go/buildutil/tags.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil

// This duplicated logic must be kept in sync with that from go build:
//   $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
//   $GOROOT/src/cmd/go/internal/base/flag.go (StringsFlag.Set)
//   $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)

import (
	"fmt"
	"strings"
)

const TagsFlagDoc = "a list of `build tags` to consider satisfied during the build. " +
	"For more information about build tags, see the description of " +
	"build constraints in the documentation for the go/build package"

// TagsFlag is an implementation of the flag.Value and flag.Getter interfaces that parses
// a flag value the same as go build's -tags flag and populates a []string slice.
//
// See $GOROOT/src/go/build/doc.go for description of build tags.
// See $GOROOT/src/cmd/go/doc.go for description of 'go build -tags' flag.
//
// Example:
//
//	flag.Var((*buildutil.TagsFlag)(&build.Default.BuildTags), "tags", buildutil.TagsFlagDoc)
type TagsFlag []string

func (v *TagsFlag) Set(s string) error {
	// See $GOROOT/src/cmd/go/internal/work/build.go (tagsFlag.Set)
	// For compatibility with Go 1.12 and earlier, allow "-tags='a b c'" or even just "-tags='a'".
	if strings.Contains(s, " ") || strings.Contains(s, "'") {
		var err error
		*v, err = splitQuotedFields(s)
		if *v == nil {
			*v = []string{}
		}
		return err
	}

	// Starting in Go 1.13, the -tags flag is a comma-separated list of build tags.
	*v = []string{}
	for s := range strings.SplitSeq(s, ",") {
		if s != "" {
			*v = append(*v, s)
		}
	}
	return nil
}

func (v *TagsFlag) Get() any { return *v }

func splitQuotedFields(s string) ([]string, error) {
	// See $GOROOT/src/cmd/internal/quoted/quoted.go (Split)
	// This must remain in sync with that logic.
	var f []string
	for len(s) > 0 {
		for len(s) > 0 && isSpaceByte(s[0]) {
			s = s[1:]
		}
		if len(s) == 0 {
			break
		}
		// Accepted quoted string. No unescaping inside.
		if s[0] == '"' || s[0] == '\'' {
			quote := s[0]
			s = s[1:]
			i := 0
			for i < len(s) && s[i] != quote {
				i++
			}
			if i >= len(s) {
				return nil, fmt.Errorf("unterminated %c string", quote)
			}
			f = append(f, s[:i])
			s = s[i+1:]
			continue
		}
		i := 0
		for i < len(s) && !isSpaceByte(s[i]) {
			i++
		}
		f = append(f, s[:i])
		s = s[i:]
	}
	return f, nil
}

func (v *TagsFlag) String() string {
	return "<tagsFlag>"
}

func isSpaceByte(c byte) bool {
	// See $GOROOT/src/cmd/internal/quoted/quoted.go (isSpaceByte, Split)
	// This list must remain in sync with that.
	return c == ' ' || c == '\t' || c == '\n' || c == '\r'
}


================================================
FILE: go/buildutil/tags_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil_test

import (
	"bytes"
	"flag"
	"go/build"
	"os/exec"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/internal/testenv"
)

func TestTags(t *testing.T) {

	type tagTestCase struct {
		tags    string
		want    []string
		wantErr bool
	}

	for name, tc := range map[string]tagTestCase{
		// Normal valid cases
		"empty": {
			tags: "",
			want: []string{},
		},
		"commas": {
			tags: "tag1,tag_2,🐹,tag/3,tag-4",
			want: []string{"tag1", "tag_2", "🐹", "tag/3", "tag-4"},
		},
		"delimiters are spaces": {
			tags: "a b\tc\rd\ne",
			want: []string{"a", "b", "c", "d", "e"},
		},
		"old quote and space form": {
			tags: "'a' 'b' 'c'",
			want: []string{"a", "b", "c"},
		},

		// Normal error cases
		"unterminated": {
			tags:    `"missing closing quote`,
			want:    []string{},
			wantErr: true,
		},
		"unterminated single": {
			tags:    `'missing closing quote`,
			want:    []string{},
			wantErr: true,
		},

		// Maybe surprising difference for unterminated quotes, no spaces
		"unterminated no spaces": {
			tags: `"missing_closing_quote`,
			want: []string{"\"missing_closing_quote"},
		},
		"unterminated no spaces single": {
			tags:    `'missing_closing_quote`,
			want:    []string{},
			wantErr: true,
		},

		// Permitted but not recommended
		"delimiters contiguous spaces": {
			tags: "a \t\r\n, b \t\r\nc,d\te\tf",
			want: []string{"a", ",", "b", "c,d", "e", "f"},
		},
		"quotes and spaces": {
			tags: ` 'one'"two"	'three "four"'`,
			want: []string{"one", "two", "three \"four\""},
		},
		"quotes single no spaces": {
			tags: `'t1','t2',"t3"`,
			want: []string{"t1", ",'t2',\"t3\""},
		},
		"quotes double no spaces": {
			tags: `"t1","t2","t3"`,
			want: []string{`"t1"`, `"t2"`, `"t3"`},
		},
	} {
		t.Run(name, func(t *testing.T) {
			f := flag.NewFlagSet("TestTags", flag.ContinueOnError)
			var ctxt build.Context
			f.Var((*buildutil.TagsFlag)(&ctxt.BuildTags), "tags", buildutil.TagsFlagDoc)

			// Normal case valid parsed tags
			f.Parse([]string{"-tags", tc.tags, "rest"})

			// BuildTags
			if !reflect.DeepEqual(ctxt.BuildTags, tc.want) {
				t.Errorf("Case = %s, BuildTags = %q, want %q", name, ctxt.BuildTags, tc.want)
			}

			// Args()
			if want := []string{"rest"}; !reflect.DeepEqual(f.Args(), want) {
				t.Errorf("Case = %s, f.Args() = %q, want %q", name, f.Args(), want)
			}

			// Regression check against base go tooling
			cmd := testenv.Command(t, "go", "list", "-f", "{{context.BuildTags}}", "-tags", tc.tags, ".")
			var out bytes.Buffer
			cmd.Stdout = &out
			if err := cmd.Run(); err != nil {
				if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
					t.Logf("stderr:\n%s", ee.Stderr)
				}
				if !tc.wantErr {
					t.Errorf("%v: %v", cmd, err)
				}
			} else if tc.wantErr {
				t.Errorf("Expected failure for %v", cmd)
			} else {
				wantDescription := strings.Join(tc.want, " ")
				output := strings.Trim(strings.TrimSuffix(out.String(), "\n"), "[]")
				if output != wantDescription {
					t.Errorf("Output = %s, want %s", output, wantDescription)
				}
			}
		})
	}
}


================================================
FILE: go/buildutil/util.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil

import (
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"io"
	"io/ioutil"
	"os"
	"path"
	"path/filepath"
	"strings"
)

// ParseFile behaves like parser.ParseFile,
// but uses the build context's file system interface, if any.
//
// If file is not absolute (as defined by IsAbsPath), the (dir, file)
// components are joined using JoinPath; dir must be absolute.
//
// The displayPath function, if provided, is used to transform the
// filename that will be attached to the ASTs.
//
// TODO(adonovan): call this from go/loader.parseFiles when the tree thaws.
func ParseFile(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, file string, mode parser.Mode) (*ast.File, error) {
	if !IsAbsPath(ctxt, file) {
		file = JoinPath(ctxt, dir, file)
	}
	rd, err := OpenFile(ctxt, file)
	if err != nil {
		return nil, err
	}
	defer rd.Close() // ignore error
	if displayPath != nil {
		file = displayPath(file)
	}
	return parser.ParseFile(fset, file, rd, mode)
}

// ContainingPackage returns the package containing filename.
//
// If filename is not absolute, it is interpreted relative to working directory dir.
// All I/O is via the build context's file system interface, if any.
//
// The '...Files []string' fields of the resulting build.Package are not
// populated (build.FindOnly mode).
func ContainingPackage(ctxt *build.Context, dir, filename string) (*build.Package, error) {
	if !IsAbsPath(ctxt, filename) {
		filename = JoinPath(ctxt, dir, filename)
	}

	// We must not assume the file tree uses
	// "/" always,
	// `\` always,
	// or os.PathSeparator (which varies by platform),
	// but to make any progress, we are forced to assume that
	// paths will not use `\` unless the PathSeparator
	// is also `\`, thus we can rely on filepath.ToSlash for some sanity.

	dirSlash := path.Dir(filepath.ToSlash(filename)) + "/"

	// We assume that no source root (GOPATH[i] or GOROOT) contains any other.
	for _, srcdir := range ctxt.SrcDirs() {
		srcdirSlash := filepath.ToSlash(srcdir) + "/"
		if importPath, ok := HasSubdir(ctxt, srcdirSlash, dirSlash); ok {
			return ctxt.Import(importPath, dir, build.FindOnly)
		}
	}

	return nil, fmt.Errorf("can't find package containing %s", filename)
}

// -- Effective methods of file system interface -------------------------

// (go/build.Context defines these as methods, but does not export them.)

// HasSubdir calls ctxt.HasSubdir (if not nil) or else uses
// the local file system to answer the question.
func HasSubdir(ctxt *build.Context, root, dir string) (rel string, ok bool) {
	if f := ctxt.HasSubdir; f != nil {
		return f(root, dir)
	}

	// Try using paths we received.
	if rel, ok = hasSubdir(root, dir); ok {
		return
	}

	// Try expanding symlinks and comparing
	// expanded against unexpanded and
	// expanded against expanded.
	rootSym, _ := filepath.EvalSymlinks(root)
	dirSym, _ := filepath.EvalSymlinks(dir)

	if rel, ok = hasSubdir(rootSym, dir); ok {
		return
	}
	if rel, ok = hasSubdir(root, dirSym); ok {
		return
	}
	return hasSubdir(rootSym, dirSym)
}

func hasSubdir(root, dir string) (rel string, ok bool) {
	const sep = string(filepath.Separator)
	root = filepath.Clean(root)
	if !strings.HasSuffix(root, sep) {
		root += sep
	}

	dir = filepath.Clean(dir)
	if !strings.HasPrefix(dir, root) {
		return "", false
	}

	return filepath.ToSlash(dir[len(root):]), true
}

// FileExists returns true if the specified file exists,
// using the build context's file system interface.
func FileExists(ctxt *build.Context, path string) bool {
	if ctxt.OpenFile != nil {
		r, err := ctxt.OpenFile(path)
		if err != nil {
			return false
		}
		r.Close() // ignore error
		return true
	}
	_, err := os.Stat(path)
	return err == nil
}

// OpenFile behaves like os.Open,
// but uses the build context's file system interface, if any.
func OpenFile(ctxt *build.Context, path string) (io.ReadCloser, error) {
	if ctxt.OpenFile != nil {
		return ctxt.OpenFile(path)
	}
	return os.Open(path)
}

// IsAbsPath behaves like filepath.IsAbs,
// but uses the build context's file system interface, if any.
func IsAbsPath(ctxt *build.Context, path string) bool {
	if ctxt.IsAbsPath != nil {
		return ctxt.IsAbsPath(path)
	}
	return filepath.IsAbs(path)
}

// JoinPath behaves like filepath.Join,
// but uses the build context's file system interface, if any.
func JoinPath(ctxt *build.Context, path ...string) string {
	if ctxt.JoinPath != nil {
		return ctxt.JoinPath(path...)
	}
	return filepath.Join(path...)
}

// IsDir behaves like os.Stat plus IsDir,
// but uses the build context's file system interface, if any.
func IsDir(ctxt *build.Context, path string) bool {
	if ctxt.IsDir != nil {
		return ctxt.IsDir(path)
	}
	fi, err := os.Stat(path)
	return err == nil && fi.IsDir()
}

// ReadDir behaves like ioutil.ReadDir,
// but uses the build context's file system interface, if any.
func ReadDir(ctxt *build.Context, path string) ([]os.FileInfo, error) {
	if ctxt.ReadDir != nil {
		return ctxt.ReadDir(path)
	}
	return ioutil.ReadDir(path)
}

// SplitPathList behaves like filepath.SplitList,
// but uses the build context's file system interface, if any.
func SplitPathList(ctxt *build.Context, s string) []string {
	if ctxt.SplitPathList != nil {
		return ctxt.SplitPathList(s)
	}
	return filepath.SplitList(s)
}

// sameFile returns true if x and y have the same basename and denote
// the same file.
func sameFile(x, y string) bool {
	if path.Clean(x) == path.Clean(y) {
		return true
	}
	if filepath.Base(x) == filepath.Base(y) { // (optimisation)
		if xi, err := os.Stat(x); err == nil {
			if yi, err := os.Stat(y); err == nil {
				return os.SameFile(xi, yi)
			}
		}
	}
	return false
}


================================================
FILE: go/buildutil/util_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil_test

import (
	"go/build"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/internal/packagestest"
)

func TestContainingPackage(t *testing.T) {
	if runtime.Compiler == "gccgo" {
		t.Skip("gccgo has no GOROOT")
	}

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{
		{Name: "golang.org/x/tools/go/buildutil", Files: packagestest.MustCopyFileTree(".")}})
	defer exported.Cleanup()

	goroot := runtime.GOROOT()
	var gopath string
	for _, env := range exported.Config.Env {
		if !strings.HasPrefix(env, "GOPATH=") {
			continue
		}
		gopath = strings.TrimPrefix(env, "GOPATH=")
	}
	if gopath == "" {
		t.Fatal("Failed to fish GOPATH out of env: ", exported.Config.Env)
	}
	buildutildir := filepath.Join(gopath, "golang.org", "x", "tools", "go", "buildutil")

	type Test struct {
		gopath, filename, wantPkg string
	}

	tests := []Test{
		{gopath, goroot + "/src/fmt/print.go", "fmt"},
		{gopath, goroot + "/src/encoding/json/foo.go", "encoding/json"},
		{gopath, goroot + "/src/encoding/missing/foo.go", "(not found)"},
		{gopath, gopath + "/src/golang.org/x/tools/go/buildutil/util_test.go",
			"golang.org/x/tools/go/buildutil"},
	}

	if runtime.GOOS != "windows" && runtime.GOOS != "plan9" {
		// Make a symlink to gopath for test
		tmp, err := os.MkdirTemp(os.TempDir(), "go")
		if err != nil {
			t.Errorf("Unable to create a temporary directory in %s", os.TempDir())
		}

		defer os.RemoveAll(tmp)

		// symlink between $GOPATH/src and /tmp/go/src
		// in order to test all possible symlink cases
		if err := os.Symlink(gopath+"/src", tmp+"/src"); err != nil {
			t.Fatal(err)
		}
		tests = append(tests, []Test{
			{gopath, tmp + "/src/golang.org/x/tools/go/buildutil/util_test.go", "golang.org/x/tools/go/buildutil"},
			{tmp, gopath + "/src/golang.org/x/tools/go/buildutil/util_test.go", "golang.org/x/tools/go/buildutil"},
			{tmp, tmp + "/src/golang.org/x/tools/go/buildutil/util_test.go", "golang.org/x/tools/go/buildutil"},
		}...)
	}

	for _, test := range tests {
		var got string
		var buildContext = build.Default
		buildContext.GOPATH = test.gopath
		bp, err := buildutil.ContainingPackage(&buildContext, buildutildir, test.filename)
		if err != nil {
			got = "(not found)"
		} else {
			got = bp.ImportPath
		}
		if got != test.wantPkg {
			t.Errorf("ContainingPackage(%q) = %s, want %s", test.filename, got, test.wantPkg)
		}
	}

}


================================================
FILE: go/buildutil/util_windows_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buildutil_test

import (
	"fmt"
	"go/build"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
)

func testContainingPackageCaseFold(file, want string) error {
	bp, err := buildutil.ContainingPackage(&build.Default, ".", file)
	if err != nil {
		return err
	}
	if got := bp.ImportPath; got != want {
		return fmt.Errorf("ContainingPackage(%q) = %s, want %s", file, got, want)
	}
	return nil
}

func TestContainingPackageCaseFold(t *testing.T) {
	path := filepath.Join(runtime.GOROOT(), `src\fmt\print.go`)
	err := testContainingPackageCaseFold(path, "fmt")
	if err != nil {
		t.Error(err)
	}
	vol := filepath.VolumeName(path)
	if len(vol) != 2 || vol[1] != ':' {
		t.Fatalf("GOROOT path has unexpected volume name: %v", vol)
	}
	rest := path[len(vol):]
	err = testContainingPackageCaseFold(strings.ToUpper(vol)+rest, "fmt")
	if err != nil {
		t.Error(err)
	}
	err = testContainingPackageCaseFold(strings.ToLower(vol)+rest, "fmt")
	if err != nil {
		t.Error(err)
	}
}


================================================
FILE: go/callgraph/callgraph.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package callgraph defines the call graph and various algorithms
and utilities to operate on it.

A call graph is a labelled directed graph whose nodes represent
functions and whose edge labels represent syntactic function call
sites.  The presence of a labelled edge (caller, site, callee)
indicates that caller may call callee at the specified call site.

A call graph is a multigraph: it may contain multiple edges (caller,
*, callee) connecting the same pair of nodes, so long as the edges
differ by label; this occurs when one function calls another function
from multiple call sites.  Also, it may contain multiple edges
(caller, site, *) that differ only by callee; this indicates a
polymorphic call.

A SOUND call graph is one that overapproximates the dynamic calling
behaviors of the program in all possible executions.  One call graph
is more PRECISE than another if it is a smaller overapproximation of
the dynamic behavior.

All call graphs have a synthetic root node which is responsible for
calling main() and init().

Calls to built-in functions (e.g. panic, println) are not represented
in the call graph; they are treated like built-in operators of the
language.
*/
package callgraph // import "golang.org/x/tools/go/callgraph"

// TODO(zpavlinovic): decide how callgraphs handle calls to and from generic function bodies.

import (
	"fmt"
	"go/token"

	"golang.org/x/tools/go/ssa"
)

// A Graph represents a call graph.
//
// A graph may contain nodes that are not reachable from the root.
// If the call graph is sound, such nodes indicate unreachable
// functions.
type Graph struct {
	Root  *Node                   // the distinguished root node (Root.Func may be nil)
	Nodes map[*ssa.Function]*Node // all nodes by function
}

// New returns a new Graph with the specified (optional) root node.
func New(root *ssa.Function) *Graph {
	g := &Graph{Nodes: make(map[*ssa.Function]*Node)}
	g.Root = g.CreateNode(root)
	return g
}

// CreateNode returns the Node for fn, creating it if not present.
// The root node may have fn=nil.
func (g *Graph) CreateNode(fn *ssa.Function) *Node {
	n, ok := g.Nodes[fn]
	if !ok {
		n = &Node{Func: fn, ID: len(g.Nodes)}
		g.Nodes[fn] = n
	}
	return n
}

// A Node represents a node in a call graph.
type Node struct {
	Func *ssa.Function // the function this node represents
	ID   int           // 0-based sequence number
	In   []*Edge       // unordered set of incoming call edges (n.In[*].Callee == n)
	Out  []*Edge       // unordered set of outgoing call edges (n.Out[*].Caller == n)
}

func (n *Node) String() string {
	return fmt.Sprintf("n%d:%s", n.ID, n.Func)
}

// A Edge represents an edge in the call graph.
//
// Site is nil for edges originating in synthetic or intrinsic
// functions, e.g. reflect.Value.Call or the root of the call graph.
type Edge struct {
	Caller *Node
	Site   ssa.CallInstruction
	Callee *Node
}

func (e Edge) String() string {
	return fmt.Sprintf("%s --> %s", e.Caller, e.Callee)
}

func (e Edge) Description() string {
	var prefix string
	switch e.Site.(type) {
	case nil:
		return "synthetic call"
	case *ssa.Go:
		prefix = "concurrent "
	case *ssa.Defer:
		prefix = "deferred "
	}
	return prefix + e.Site.Common().Description()
}

func (e Edge) Pos() token.Pos {
	if e.Site == nil {
		return token.NoPos
	}
	return e.Site.Pos()
}

// AddEdge adds the edge (caller, site, callee) to the call graph.
// Elimination of duplicate edges is the caller's responsibility.
func AddEdge(caller *Node, site ssa.CallInstruction, callee *Node) {
	e := &Edge{caller, site, callee}
	callee.In = append(callee.In, e)
	caller.Out = append(caller.Out, e)
}


================================================
FILE: go/callgraph/callgraph_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package callgraph_test

import (
	"sync"
	"testing"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/callgraph/rta"
	"golang.org/x/tools/go/callgraph/static"
	"golang.org/x/tools/go/callgraph/vta"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// Benchmarks comparing different callgraph algorithms implemented in
// x/tools/go/callgraph. Comparison is on both speed, memory and precision.
// Fewer edges and fewer reachable nodes implies a more precise result.
// Comparison is done on a hello world http server using net/http.
//
// Current results were on an i7 macbook on go version devel go1.20-2730.
// Number of nodes, edges, and reachable function are expected to vary between
// go versions. Timing results are expected to vary between machines.
// BenchmarkStatic-12	 53 ms/op     6 MB/op	12113 nodes	 37355 edges	1522 reachable
// BenchmarkCHA-12    	 86 ms/op	 16 MB/op	12113 nodes	131717 edges	7640 reachable
// BenchmarkRTA-12		110 ms/op	 12 MB/op	 6566 nodes	 42291 edges	5099 reachable
// BenchmarkPTA-12	   1427 ms/op	600 MB/op	 8714 nodes	 28244 edges	4184 reachable
// BenchmarkVTA-12		600 ms/op	 78 MB/op	12114 nodes	 44861 edges	4919 reachable
// BenchmarkVTA2-12		793 ms/op	104 MB/op	 5450 nodes	 22208 edges	4042 reachable
// BenchmarkVTA3-12		977 ms/op	124 MB/op	 4621 nodes	 19331 edges	3700 reachable
// BenchmarkVTAAlt-12	372 ms/op	 57 MB/op	 7763 nodes	 29912 edges	4258 reachable
// BenchmarkVTAAlt2-12	570 ms/op	 78 MB/op	 4838 nodes	 20169 edges	3737 reachable
//
// Note:
// * Static is unsound and may miss real edges.
// * RTA starts from a main function and only includes reachable functions.
// * CHA starts from all functions.
// * VTA, VTA2, and VTA3 are starting from all functions and the CHA callgraph.
//   VTA2 and VTA3 are the result of re-applying VTA to the functions reachable
//   from main() via the callgraph of the previous stage.
// * VTAAlt, and VTAAlt2 start from the functions reachable from main via the
//   CHA callgraph.
// * All algorithms are unsound w.r.t. reflection.

const httpEx = `
-- go.mod --
module x.io

-- main.go --
package main

import (
    "fmt"
    "net/http"
)

func hello(w http.ResponseWriter, req *http.Request) {
    fmt.Fprintf(w, "hello world\n")
}

func main() {
    http.HandleFunc("/hello", hello)
    http.ListenAndServe(":8090", nil)
}
`

var (
	once sync.Once
	main *ssa.Function
)

func example(t testing.TB) (*ssa.Program, *ssa.Function) {
	once.Do(func() {
		pkgs := testfiles.LoadPackages(t, txtar.Parse([]byte(httpEx)), ".")
		prog, ssapkgs := ssautil.Packages(pkgs, ssa.InstantiateGenerics)
		prog.Build()
		main = ssapkgs[0].Members["main"].(*ssa.Function)
	})
	return main.Prog, main
}

var stats bool = false // print stats?

func logStats(b *testing.B, cnd bool, name string, cg *callgraph.Graph, main *ssa.Function) {
	if cnd && stats {
		e := 0
		for _, n := range cg.Nodes {
			e += len(n.Out)
		}
		r := len(reaches(main, cg, false))
		b.Logf("%s:\t%d nodes\t%d edges\t%d reachable", name, len(cg.Nodes), e, r)
	}
}

func BenchmarkStatic(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		cg := static.CallGraph(prog)
		logStats(b, i == 0, "static", cg, main)
	}
}

func BenchmarkCHA(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		cg := cha.CallGraph(prog)
		logStats(b, i == 0, "cha", cg, main)
	}
}

func BenchmarkRTA(b *testing.B) {

	_, main := example(b)

	for i := 0; b.Loop(); i++ {
		res := rta.Analyze([]*ssa.Function{main}, true)
		cg := res.CallGraph
		logStats(b, i == 0, "rta", cg, main)
	}
}

func BenchmarkVTA(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		cg := vta.CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
		logStats(b, i == 0, "vta", cg, main)
	}
}

func BenchmarkVTA2(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		vta1 := vta.CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
		cg := vta.CallGraph(reaches(main, vta1, true), vta1)
		logStats(b, i == 0, "vta2", cg, main)
	}
}

func BenchmarkVTA3(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		vta1 := vta.CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
		vta2 := vta.CallGraph(reaches(main, vta1, true), vta1)
		cg := vta.CallGraph(reaches(main, vta2, true), vta2)
		logStats(b, i == 0, "vta3", cg, main)
	}
}

func BenchmarkVTAAlt(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		cha := cha.CallGraph(prog)
		cg := vta.CallGraph(reaches(main, cha, true), cha) // start from only functions reachable by CHA.
		logStats(b, i == 0, "vta-alt", cg, main)
	}
}

func BenchmarkVTAAlt2(b *testing.B) {

	prog, main := example(b)

	for i := 0; b.Loop(); i++ {
		cha := cha.CallGraph(prog)
		vta1 := vta.CallGraph(reaches(main, cha, true), cha)
		cg := vta.CallGraph(reaches(main, vta1, true), vta1)
		logStats(b, i == 0, "vta-alt2", cg, main)
	}
}

// reaches computes the transitive closure of functions forward reachable
// via calls in cg starting from `sources`. If refs is true, include
// functions referred to in an instruction.
func reaches(source *ssa.Function, cg *callgraph.Graph, refs bool) map[*ssa.Function]bool {
	seen := make(map[*ssa.Function]bool)
	var visit func(f *ssa.Function)
	visit = func(f *ssa.Function) {
		if seen[f] {
			return
		}
		seen[f] = true

		if n := cg.Nodes[f]; n != nil {
			for _, e := range n.Out {
				if e.Site != nil {
					visit(e.Callee.Func)
				}
			}
		}

		if refs {
			var buf [10]*ssa.Value // avoid alloc in common case
			for _, b := range f.Blocks {
				for _, instr := range b.Instrs {
					for _, op := range instr.Operands(buf[:0]) {
						if fn, ok := (*op).(*ssa.Function); ok {
							visit(fn)
						}
					}
				}
			}
		}
	}
	visit(source)
	return seen
}


================================================
FILE: go/callgraph/cha/cha.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cha computes the call graph of a Go program using the Class
// Hierarchy Analysis (CHA) algorithm.
//
// CHA was first described in "Optimization of Object-Oriented Programs
// Using Static Class Hierarchy Analysis", Jeffrey Dean, David Grove,
// and Craig Chambers, ECOOP'95.
//
// CHA is related to RTA (see go/callgraph/rta); the difference is that
// CHA conservatively computes the entire "implements" relation between
// interfaces and concrete types ahead of time, whereas RTA uses dynamic
// programming to construct it on the fly as it encounters new functions
// reachable from main.  CHA may thus include spurious call edges for
// types that haven't been instantiated yet, or types that are never
// instantiated.
//
// Since CHA conservatively assumes that all functions are address-taken
// and all concrete types are put into interfaces, it is sound to run on
// partial programs, such as libraries without a main or test function.
package cha // import "golang.org/x/tools/go/callgraph/cha"

// TODO(zpavlinovic): update CHA for how it handles generic function bodies.

import (
	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/internal/chautil"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

// CallGraph computes the call graph of the specified program using the
// Class Hierarchy Analysis algorithm.
func CallGraph(prog *ssa.Program) *callgraph.Graph {
	cg := callgraph.New(nil) // TODO(adonovan) eliminate concept of rooted callgraph

	allFuncs := ssautil.AllFunctions(prog)

	calleesOf := lazyCallees(allFuncs)

	addEdge := func(fnode *callgraph.Node, site ssa.CallInstruction, g *ssa.Function) {
		gnode := cg.CreateNode(g)
		callgraph.AddEdge(fnode, site, gnode)
	}

	addEdges := func(fnode *callgraph.Node, site ssa.CallInstruction, callees []*ssa.Function) {
		// Because every call to a highly polymorphic and
		// frequently used abstract method such as
		// (io.Writer).Write is assumed to call every concrete
		// Write method in the program, the call graph can
		// contain a lot of duplication.
		for _, g := range callees {
			addEdge(fnode, site, g)
		}
	}

	for f := range allFuncs {
		fnode := cg.CreateNode(f)
		for _, b := range f.Blocks {
			for _, instr := range b.Instrs {
				if site, ok := instr.(ssa.CallInstruction); ok {
					if g := site.Common().StaticCallee(); g != nil {
						addEdge(fnode, site, g)
					} else {
						addEdges(fnode, site, calleesOf(site))
					}
				}
			}
		}
	}

	return cg
}

var lazyCallees = chautil.LazyCallees


================================================
FILE: go/callgraph/cha/cha_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package cha_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

var inputs = []string{
	"testdata/func.go",
	"testdata/iface.go",
	"testdata/recv.go",
	"testdata/issue23925.go",
}

func expectation(f *ast.File) (string, token.Pos) {
	for _, c := range f.Comments {
		text := strings.TrimSpace(c.Text())
		if t, ok := strings.CutPrefix(text, "WANT:\n"); ok {
			return t, c.Pos()
		}
	}
	return "", token.NoPos
}

// TestCHA runs CHA on each file in inputs, prints the dynamic edges of
// the call graph, and compares it with the golden results embedded in
// the WANT comment at the end of the file.
func TestCHA(t *testing.T) {
	for _, filename := range inputs {
		pkg, ssapkg := loadFile(t, filename, ssa.InstantiateGenerics)

		want, pos := expectation(pkg.Syntax[0])
		if pos == token.NoPos {
			t.Error(fmt.Errorf("No WANT: comment in %s", filename))
			continue
		}

		cg := cha.CallGraph(ssapkg.Prog)

		if got := printGraph(cg, pkg.Types, "dynamic", "Dynamic calls"); got != want {
			t.Errorf("%s: got:\n%s\nwant:\n%s",
				ssapkg.Prog.Fset.Position(pos), got, want)
		}
	}
}

// TestCHAGenerics is TestCHA tailored for testing generics,
func TestCHAGenerics(t *testing.T) {
	filename := "testdata/generics.go"
	pkg, ssapkg := loadFile(t, filename, ssa.InstantiateGenerics)

	want, pos := expectation(pkg.Syntax[0])
	if pos == token.NoPos {
		t.Fatal(fmt.Errorf("No WANT: comment in %s", filename))
	}

	cg := cha.CallGraph(ssapkg.Prog)

	if got := printGraph(cg, pkg.Types, "", "All calls"); got != want {
		t.Errorf("%s: got:\n%s\nwant:\n%s",
			ssapkg.Prog.Fset.Position(pos), got, want)
	}
}

// TestCHAUnexported tests call resolution for unexported methods.
func TestCHAUnexported(t *testing.T) {
	// The two packages below each have types with methods called "m".
	// Each of these methods should only be callable by functions in their
	// own package, because they are unexported.
	//
	// In particular:
	// - main.main can call    (main.S1).m
	// - p2.Foo    can call    (p2.S2).m
	// - main.main cannot call (p2.S2).m
	// - p2.Foo    cannot call (main.S1).m
	//
	// We use CHA to build a callgraph, then check that it has the
	// appropriate set of edges.

	const src = `
-- go.mod --
module x.io
go 1.18

-- main/main.go --
package main

import "x.io/p2"

type I1 interface { m() }
type S1 struct { p2.I2 }
func (s S1) m() { }
func main() {
	var s S1
	var o I1 = s
	o.m()
	p2.Foo(s)
}

-- p2/p2.go --
package p2

type I2 interface { m() }
type S2 struct { }
func (s S2) m() { }
func Foo(i I2) { i.m() }
`

	want := `All calls
  x.io/main.init --> x.io/p2.init
  x.io/main.main --> (x.io/main.S1).m
  x.io/main.main --> x.io/p2.Foo
  x.io/p2.Foo --> (x.io/p2.S2).m`

	pkgs := testfiles.LoadPackages(t, txtar.Parse([]byte(src)), "./...")
	prog, _ := ssautil.Packages(pkgs, ssa.InstantiateGenerics)
	prog.Build()

	cg := cha.CallGraph(prog)

	// The graph is easier to read without synthetic nodes.
	cg.DeleteSyntheticNodes()

	if got := printGraph(cg, nil, "", "All calls"); got != want {
		t.Errorf("cha.CallGraph: got:\n%s\nwant:\n%s", got, want)
	}
}

// loadFile loads a built SSA package for a single-file "x.io/main" package.
// (Ideally all uses would be converted over to txtar files with explicit go.mod files.)
func loadFile(t testing.TB, filename string, mode ssa.BuilderMode) (*packages.Package, *ssa.Package) {
	testenv.NeedsGoPackages(t)

	data, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	dir := t.TempDir()
	cfg := &packages.Config{
		Mode: packages.LoadAllSyntax,
		Dir:  dir,
		Overlay: map[string][]byte{
			filepath.Join(dir, "go.mod"):       []byte("module x.io\ngo 1.22"),
			filepath.Join(dir, "main/main.go"): data,
		},
		Env: append(os.Environ(), "GO111MODULES=on", "GOPATH=", "GOWORK=off", "GOPROXY=off"),
	}
	pkgs, err := packages.Load(cfg, "./main")
	if err != nil {
		t.Fatal(err)
	}
	if num := packages.PrintErrors(pkgs); num > 0 {
		t.Fatalf("packages contained %d errors", num)
	}
	prog, ssapkgs := ssautil.Packages(pkgs, mode)
	prog.Build()
	return pkgs[0], ssapkgs[0]
}

// printGraph returns a string representation of cg involving only edges
// whose description contains edgeMatch. The string representation is
// prefixed with a desc line.
func printGraph(cg *callgraph.Graph, from *types.Package, edgeMatch string, desc string) string {
	var edges []string
	callgraph.GraphVisitEdges(cg, func(e *callgraph.Edge) error {
		if strings.Contains(e.Description(), edgeMatch) {
			edges = append(edges, fmt.Sprintf("%s --> %s",
				e.Caller.Func.RelString(from),
				e.Callee.Func.RelString(from)))
		}
		return nil
	})
	sort.Strings(edges)

	var buf bytes.Buffer
	buf.WriteString(desc + "\n")
	for _, edge := range edges {
		fmt.Fprintf(&buf, "  %s\n", edge)
	}
	return strings.TrimSpace(buf.String())
}


================================================
FILE: go/callgraph/cha/testdata/func.go
================================================
package main

// Test of dynamic function calls; no interfaces.

func A(int) {}

var (
	B = func(int) {}
	C = func(int) {}
)

func f() {
	pfn := B
	pfn(0) // calls A, B, C, even though A is not even address-taken
}

// WANT:
// Dynamic calls
//   f --> A
//   f --> init$1
//   f --> init$2


================================================
FILE: go/callgraph/cha/testdata/generics.go
================================================
package main

// Test of generic function calls.

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

func instantiated[X I](x X) {
	x.Foo()
}

func Bar() {}

func f(h func(), g func(I), k func(A), a A, b B) {
	h()

	k(a)
	g(b) // g:func(I) is not matched by instantiated[B]:func(B)

	instantiated[A](a) // static call
	instantiated[B](b) // static call
}

// WANT:
// All calls
//   (*A).Foo --> (A).Foo
//   (*B).Foo --> (B).Foo
//   f --> Bar
//   f --> instantiated[x.io/main.A]
//   f --> instantiated[x.io/main.A]
//   f --> instantiated[x.io/main.B]
//   instantiated --> (*A).Foo
//   instantiated --> (*B).Foo
//   instantiated --> (A).Foo
//   instantiated --> (B).Foo
//   instantiated[x.io/main.A] --> (A).Foo
//   instantiated[x.io/main.B] --> (B).Foo


================================================
FILE: go/callgraph/cha/testdata/iface.go
================================================
package main

// Test of interface calls.  None of the concrete types are ever
// instantiated or converted to interfaces.

type I interface {
	f()
}

type J interface {
	f()
	g()
}

type C int // implements I

func (*C) f()

type D int // implements I and J

func (*D) f()
func (*D) g()

func one(i I, j J) {
	i.f() // calls *C and *D
}

func two(i I, j J) {
	j.f() // calls *D (but not *C, even though it defines method f)
}

func three(i I, j J) {
	j.g() // calls *D
}

func four(i I, j J) {
	Jf := J.f
	if unknown {
		Jf = nil // suppress SSA constant propagation
	}
	Jf(nil) // calls *D
}

func five(i I, j J) {
	jf := j.f
	if unknown {
		jf = nil // suppress SSA constant propagation
	}
	jf() // calls *D
}

var unknown bool

// WANT:
// Dynamic calls
//   (J).f$bound --> (*D).f
//   (J).f$thunk --> (*D).f
//   five --> (J).f$bound
//   four --> (J).f$thunk
//   one --> (*C).f
//   one --> (*D).f
//   three --> (*D).g
//   two --> (*D).f


================================================
FILE: go/callgraph/cha/testdata/issue23925.go
================================================
package main

// Regression test for https://golang.org/issue/23925

type stringFlagImpl string

func (*stringFlagImpl) Set(s string) error { return nil }

type boolFlagImpl bool

func (*boolFlagImpl) Set(s string) error { return nil }
func (*boolFlagImpl) extra()             {}

// A copy of flag.boolFlag interface, without a dependency.
// Must appear first, so that it becomes the owner of the Set methods.
type boolFlag interface {
	flagValue
	extra()
}

// A copy of flag.Value, without adding a dependency.
type flagValue interface {
	Set(string) error
}

func main() {
	var x flagValue = new(stringFlagImpl)
	x.Set("")

	var y boolFlag = new(boolFlagImpl)
	y.Set("")
}

// WANT:
// Dynamic calls
//   main --> (*boolFlagImpl).Set
//   main --> (*boolFlagImpl).Set
//   main --> (*stringFlagImpl).Set


================================================
FILE: go/callgraph/cha/testdata/recv.go
================================================
package main

type I interface {
	f()
}

type J interface {
	g()
}

type C int // C and *C implement I; *C implements J

func (C) f()
func (*C) g()

type D int // *D implements I and J

func (*D) f()
func (*D) g()

func f(i I) {
	i.f() // calls C, *C, *D
}

func g(j J) {
	j.g() // calls *C, *D
}

// WANT:
// Dynamic calls
//   f --> (*C).f
//   f --> (*D).f
//   f --> (C).f
//   g --> (*C).g
//   g --> (*D).g


================================================
FILE: go/callgraph/internal/chautil/lazy.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package chautil provides helper functions related to
// class hierarchy analysis (CHA) for use in x/tools.
package chautil

import (
	"go/types"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/types/typeutil"
)

// LazyCallees returns a function that maps a call site (in a function in fns)
// to its callees within fns. The set of callees is computed using the CHA algorithm,
// i.e., on the entire implements relation between interfaces and concrete types
// in fns. Please see golang.org/x/tools/go/callgraph/cha for more information.
//
// The resulting function is not concurrency safe.
func LazyCallees(fns map[*ssa.Function]bool) func(site ssa.CallInstruction) []*ssa.Function {
	// funcsBySig contains all functions, keyed by signature.  It is
	// the effective set of address-taken functions used to resolve
	// a dynamic call of a particular signature.
	var funcsBySig typeutil.Map // value is []*ssa.Function

	// methodsByID contains all methods, grouped by ID for efficient
	// lookup.
	//
	// We must key by ID, not name, for correct resolution of interface
	// calls to a type with two (unexported) methods spelled the same but
	// from different packages. The fact that the concrete type implements
	// the interface does not mean the call dispatches to both methods.
	methodsByID := make(map[string][]*ssa.Function)

	// An imethod represents an interface method I.m.
	// (There's no go/types object for it;
	// a *types.Func may be shared by many interfaces due to interface embedding.)
	type imethod struct {
		I  *types.Interface
		id string
	}
	// methodsMemo records, for every abstract method call I.m on
	// interface type I, the set of concrete methods C.m of all
	// types C that satisfy interface I.
	//
	// Abstract methods may be shared by several interfaces,
	// hence we must pass I explicitly, not guess from m.
	//
	// methodsMemo is just a cache, so it needn't be a typeutil.Map.
	methodsMemo := make(map[imethod][]*ssa.Function)
	lookupMethods := func(I *types.Interface, m *types.Func) []*ssa.Function {
		id := m.Id()
		methods, ok := methodsMemo[imethod{I, id}]
		if !ok {
			for _, f := range methodsByID[id] {
				C := f.Signature.Recv().Type() // named or *named
				if types.Implements(C, I) {
					methods = append(methods, f)
				}
			}
			methodsMemo[imethod{I, id}] = methods
		}
		return methods
	}

	for f := range fns {
		if f.Signature.Recv() == nil {
			// Package initializers can never be address-taken.
			if f.Name() == "init" && f.Synthetic == "package initializer" {
				continue
			}
			funcs, _ := funcsBySig.At(f.Signature).([]*ssa.Function)
			funcs = append(funcs, f)
			funcsBySig.Set(f.Signature, funcs)
		} else if obj := f.Object(); obj != nil {
			id := obj.(*types.Func).Id()
			methodsByID[id] = append(methodsByID[id], f)
		}
	}

	return func(site ssa.CallInstruction) []*ssa.Function {
		call := site.Common()
		if call.IsInvoke() {
			tiface := call.Value.Type().Underlying().(*types.Interface)
			return lookupMethods(tiface, call.Method)
		} else if g := call.StaticCallee(); g != nil {
			return []*ssa.Function{g}
		} else if _, ok := call.Value.(*ssa.Builtin); !ok {
			fns, _ := funcsBySig.At(call.Signature()).([]*ssa.Function)
			return fns
		}
		return nil
	}
}


================================================
FILE: go/callgraph/rta/rta.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This package provides Rapid Type Analysis (RTA) for Go, a fast
// algorithm for call graph construction and discovery of reachable code
// (and hence dead code) and runtime types.  The algorithm was first
// described in:
//
// David F. Bacon and Peter F. Sweeney. 1996.
// Fast static analysis of C++ virtual function calls. (OOPSLA '96)
// http://doi.acm.org/10.1145/236337.236371
//
// The algorithm uses dynamic programming to tabulate the cross-product
// of the set of known "address-taken" functions with the set of known
// dynamic calls of the same type.  As each new address-taken function
// is discovered, call graph edges are added from each known callsite,
// and as each new call site is discovered, call graph edges are added
// from it to each known address-taken function.
//
// A similar approach is used for dynamic calls via interfaces: it
// tabulates the cross-product of the set of known "runtime types",
// i.e. types that may appear in an interface value, or may be derived from
// one via reflection, with the set of known "invoke"-mode dynamic
// calls.  As each new runtime type is discovered, call edges are
// added from the known call sites, and as each new call site is
// discovered, call graph edges are added to each compatible
// method.
//
// In addition, we must consider as reachable all address-taken
// functions and all exported methods of any runtime type, since they
// may be called via reflection.
//
// Each time a newly added call edge causes a new function to become
// reachable, the code of that function is analyzed for more call sites,
// address-taken functions, and runtime types.  The process continues
// until a fixed point is reached.
package rta // import "golang.org/x/tools/go/callgraph/rta"

import (
	"fmt"
	"go/types"
	"hash/crc32"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/types/typeutil"
)

// A Result holds the results of Rapid Type Analysis, which includes the
// set of reachable functions/methods, runtime types, and the call graph.
type Result struct {
	// CallGraph is the discovered callgraph.
	// It does not include edges for calls made via reflection.
	CallGraph *callgraph.Graph

	// Reachable contains the set of reachable functions and methods.
	// This includes exported methods of runtime types, since
	// they may be accessed via reflection.
	// The value indicates whether the function is address-taken.
	//
	// (We wrap the bool in a struct to avoid inadvertent use of
	// "if Reachable[f] {" to test for set membership.)
	Reachable map[*ssa.Function]struct{ AddrTaken bool }

	// RuntimeTypes contains the set of types that are needed at
	// runtime, for interfaces or reflection.
	//
	// The value indicates whether the type is inaccessible to reflection.
	// Consider:
	// 	type A struct{B}
	// 	fmt.Println(new(A))
	// Types *A, A and B are accessible to reflection, but the unnamed
	// type struct{B} is not.
	RuntimeTypes typeutil.Map
}

// Working state of the RTA algorithm.
type rta struct {
	result *Result

	prog *ssa.Program

	reflectValueCall *ssa.Function // (*reflect.Value).Call, iff part of prog

	worklist []*ssa.Function // list of functions to visit

	// addrTakenFuncsBySig contains all address-taken *Functions, grouped by signature.
	// Keys are *types.Signature, values are map[*ssa.Function]bool sets.
	addrTakenFuncsBySig typeutil.Map

	// dynCallSites contains all dynamic "call"-mode call sites, grouped by signature.
	// Keys are *types.Signature, values are unordered []ssa.CallInstruction.
	dynCallSites typeutil.Map

	// invokeSites contains all "invoke"-mode call sites, grouped by interface.
	// Keys are *types.Interface (never *types.Named),
	// Values are unordered []ssa.CallInstruction sets.
	invokeSites typeutil.Map

	// The following two maps together define the subset of the
	// m:n "implements" relation needed by the algorithm.

	// concreteTypes maps each concrete type to information about it.
	// Keys are types.Type, values are *concreteTypeInfo.
	// Only concrete types used as MakeInterface operands are included.
	concreteTypes typeutil.Map

	// interfaceTypes maps each interface type to information about it.
	// Keys are *types.Interface, values are *interfaceTypeInfo.
	// Only interfaces used in "invoke"-mode CallInstructions are included.
	interfaceTypes typeutil.Map
}

type concreteTypeInfo struct {
	C          types.Type
	mset       *types.MethodSet
	fprint     uint64             // fingerprint of method set
	implements []*types.Interface // unordered set of implemented interfaces
}

type interfaceTypeInfo struct {
	I               *types.Interface
	mset            *types.MethodSet
	fprint          uint64
	implementations []types.Type // unordered set of concrete implementations
}

// addReachable marks a function as potentially callable at run-time,
// and ensures that it gets processed.
func (r *rta) addReachable(f *ssa.Function, addrTaken bool) {
	reachable := r.result.Reachable
	n := len(reachable)
	v := reachable[f]
	if addrTaken {
		v.AddrTaken = true
	}
	reachable[f] = v
	if len(reachable) > n {
		// First time seeing f.  Add it to the worklist.
		r.worklist = append(r.worklist, f)
	}
}

// addEdge adds the specified call graph edge, and marks it reachable.
// addrTaken indicates whether to mark the callee as "address-taken".
// site is nil for calls made via reflection.
func (r *rta) addEdge(caller *ssa.Function, site ssa.CallInstruction, callee *ssa.Function, addrTaken bool) {
	r.addReachable(callee, addrTaken)

	if g := r.result.CallGraph; g != nil {
		if caller == nil {
			panic(site)
		}
		from := g.CreateNode(caller)
		to := g.CreateNode(callee)
		callgraph.AddEdge(from, site, to)
	}
}

// ---------- addrTakenFuncs × dynCallSites ----------

// visitAddrTakenFunc is called each time we encounter an address-taken function f.
func (r *rta) visitAddrTakenFunc(f *ssa.Function) {
	// Create two-level map (Signature -> Function -> bool).
	S := f.Signature
	funcs, _ := r.addrTakenFuncsBySig.At(S).(map[*ssa.Function]bool)
	if funcs == nil {
		funcs = make(map[*ssa.Function]bool)
		r.addrTakenFuncsBySig.Set(S, funcs)
	}
	if !funcs[f] {
		// First time seeing f.
		funcs[f] = true

		// If we've seen any dyncalls of this type, mark it reachable,
		// and add call graph edges.
		sites, _ := r.dynCallSites.At(S).([]ssa.CallInstruction)
		for _, site := range sites {
			r.addEdge(site.Parent(), site, f, true)
		}

		// If the program includes (*reflect.Value).Call,
		// add a dynamic call edge from it to any address-taken
		// function, regardless of signature.
		//
		// This isn't perfect.
		// - The actual call comes from an internal function
		//   called reflect.call, but we can't rely on that here.
		// - reflect.Value.CallSlice behaves similarly,
		//   but we don't bother to create callgraph edges from
		//   it as well as it wouldn't fundamentally change the
		//   reachability but it would add a bunch more edges.
		// - We assume that if reflect.Value.Call is among
		//   the dependencies of the application, it is itself
		//   reachable. (It would be more accurate to defer
		//   all the addEdges below until r.V.Call itself
		//   becomes reachable.)
		// - Fake call graph edges are added from r.V.Call to
		//   each address-taken function, but not to every
		//   method reachable through a materialized rtype,
		//   which is a little inconsistent. Still, the
		//   reachable set includes both kinds, which is what
		//   matters for e.g. deadcode detection.)
		if r.reflectValueCall != nil {
			var site ssa.CallInstruction = nil // can't find actual call site
			r.addEdge(r.reflectValueCall, site, f, true)
		}
	}
}

// visitDynCall is called each time we encounter a dynamic "call"-mode call.
func (r *rta) visitDynCall(site ssa.CallInstruction) {
	S := site.Common().Signature()

	// Record the call site.
	sites, _ := r.dynCallSites.At(S).([]ssa.CallInstruction)
	r.dynCallSites.Set(S, append(sites, site))

	// For each function of signature S that we know is address-taken,
	// add an edge and mark it reachable.
	funcs, _ := r.addrTakenFuncsBySig.At(S).(map[*ssa.Function]bool)
	for g := range funcs {
		r.addEdge(site.Parent(), site, g, true)
	}
}

// ---------- concrete types × invoke sites ----------

// addInvokeEdge is called for each new pair (site, C) in the matrix.
func (r *rta) addInvokeEdge(site ssa.CallInstruction, C types.Type) {
	// Ascertain the concrete method of C to be called.
	imethod := site.Common().Method
	cmethod := r.prog.LookupMethod(C, imethod.Pkg(), imethod.Name())
	r.addEdge(site.Parent(), site, cmethod, true)
}

// visitInvoke is called each time the algorithm encounters an "invoke"-mode call.
func (r *rta) visitInvoke(site ssa.CallInstruction) {
	I := site.Common().Value.Type().Underlying().(*types.Interface)

	// Record the invoke site.
	sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
	r.invokeSites.Set(I, append(sites, site))

	// Add callgraph edge for each existing
	// address-taken concrete type implementing I.
	for _, C := range r.implementations(I) {
		r.addInvokeEdge(site, C)
	}
}

// ---------- main algorithm ----------

// visitFunc processes function f.
func (r *rta) visitFunc(f *ssa.Function) {
	var space [32]*ssa.Value // preallocate space for common case

	for _, b := range f.Blocks {
		for _, instr := range b.Instrs {
			rands := instr.Operands(space[:0])

			switch instr := instr.(type) {
			case ssa.CallInstruction:
				call := instr.Common()
				if call.IsInvoke() {
					r.visitInvoke(instr)
				} else if g := call.StaticCallee(); g != nil {
					r.addEdge(f, instr, g, false)
				} else if _, ok := call.Value.(*ssa.Builtin); !ok {
					r.visitDynCall(instr)
				}

				// Ignore the call-position operand when
				// looking for address-taken Functions.
				// Hack: assume this is rands[0].
				rands = rands[1:]

			case *ssa.MakeInterface:
				// Converting a value of type T to an
				// interface materializes its runtime
				// type, allowing any of its exported
				// methods to be called though reflection.
				r.addRuntimeType(instr.X.Type(), false)
			}

			// Process all address-taken functions.
			for _, op := range rands {
				if g, ok := (*op).(*ssa.Function); ok {
					r.visitAddrTakenFunc(g)
				}
			}
		}
	}
}

// Analyze performs Rapid Type Analysis, starting at the specified root
// functions.  It returns nil if no roots were specified.
//
// The root functions must be one or more entrypoints (main and init
// functions) of a complete SSA program, with function bodies for all
// dependencies, constructed with the [ssa.InstantiateGenerics] mode
// flag.
//
// If buildCallGraph is true, Result.CallGraph will contain a call
// graph; otherwise, only the other fields (reachable functions) are
// populated.
func Analyze(roots []*ssa.Function, buildCallGraph bool) *Result {
	if len(roots) == 0 {
		return nil
	}

	r := &rta{
		result: &Result{Reachable: make(map[*ssa.Function]struct{ AddrTaken bool })},
		prog:   roots[0].Prog,
	}

	if buildCallGraph {
		// TODO(adonovan): change callgraph API to eliminate the
		// notion of a distinguished root node.  Some callgraphs
		// have many roots, or none.
		r.result.CallGraph = callgraph.New(roots[0])
	}

	// Grab ssa.Function for (*reflect.Value).Call,
	// if "reflect" is among the dependencies.
	if reflectPkg := r.prog.ImportedPackage("reflect"); reflectPkg != nil {
		reflectValue := reflectPkg.Members["Value"].(*ssa.Type)
		r.reflectValueCall = r.prog.LookupMethod(reflectValue.Object().Type(), reflectPkg.Pkg, "Call")
	}

	hasher := typeutil.MakeHasher()
	r.result.RuntimeTypes.SetHasher(hasher)
	r.addrTakenFuncsBySig.SetHasher(hasher)
	r.dynCallSites.SetHasher(hasher)
	r.invokeSites.SetHasher(hasher)
	r.concreteTypes.SetHasher(hasher)
	r.interfaceTypes.SetHasher(hasher)

	for _, root := range roots {
		r.addReachable(root, false)
	}

	// Visit functions, processing their instructions, and adding
	// new functions to the worklist, until a fixed point is
	// reached.
	var shadow []*ssa.Function // for efficiency, we double-buffer the worklist
	for len(r.worklist) > 0 {
		shadow, r.worklist = r.worklist, shadow[:0]
		for _, f := range shadow {
			r.visitFunc(f)
		}
	}
	return r.result
}

// interfaces(C) returns all currently known interfaces implemented by C.
func (r *rta) interfaces(C types.Type) []*types.Interface {
	// Create an info for C the first time we see it.
	var cinfo *concreteTypeInfo
	if v := r.concreteTypes.At(C); v != nil {
		cinfo = v.(*concreteTypeInfo)
	} else {
		mset := r.prog.MethodSets.MethodSet(C)
		cinfo = &concreteTypeInfo{
			C:      C,
			mset:   mset,
			fprint: fingerprint(mset),
		}
		r.concreteTypes.Set(C, cinfo)

		// Ascertain set of interfaces C implements
		// and update the 'implements' relation.
		r.interfaceTypes.Iterate(func(I types.Type, v any) {
			iinfo := v.(*interfaceTypeInfo)
			if I := types.Unalias(I).(*types.Interface); implements(cinfo, iinfo) {
				iinfo.implementations = append(iinfo.implementations, C)
				cinfo.implements = append(cinfo.implements, I)
			}
		})
	}

	return cinfo.implements
}

// implementations(I) returns all currently known concrete types that implement I.
func (r *rta) implementations(I *types.Interface) []types.Type {
	// Create an info for I the first time we see it.
	var iinfo *interfaceTypeInfo
	if v := r.interfaceTypes.At(I); v != nil {
		iinfo = v.(*interfaceTypeInfo)
	} else {
		mset := r.prog.MethodSets.MethodSet(I)
		iinfo = &interfaceTypeInfo{
			I:      I,
			mset:   mset,
			fprint: fingerprint(mset),
		}
		r.interfaceTypes.Set(I, iinfo)

		// Ascertain set of concrete types that implement I
		// and update the 'implements' relation.
		r.concreteTypes.Iterate(func(C types.Type, v any) {
			cinfo := v.(*concreteTypeInfo)
			if implements(cinfo, iinfo) {
				cinfo.implements = append(cinfo.implements, I)
				iinfo.implementations = append(iinfo.implementations, C)
			}
		})
	}
	return iinfo.implementations
}

// addRuntimeType is called for each concrete type that can be the
// dynamic type of some interface or reflect.Value.
// Adapted from needMethods in go/ssa/builder.go
func (r *rta) addRuntimeType(T types.Type, skip bool) {
	// Never record aliases.
	T = types.Unalias(T)

	if prev, ok := r.result.RuntimeTypes.At(T).(bool); ok {
		if skip && !prev {
			r.result.RuntimeTypes.Set(T, skip)
		}
		return
	}
	r.result.RuntimeTypes.Set(T, skip)

	mset := r.prog.MethodSets.MethodSet(T)

	if _, ok := T.Underlying().(*types.Interface); !ok {
		// T is a new concrete type.
		for i, n := 0, mset.Len(); i < n; i++ {
			sel := mset.At(i)
			m := sel.Obj()

			if m.Exported() {
				// Exported methods are always potentially callable via reflection.
				r.addReachable(r.prog.MethodValue(sel), true)
			}
		}

		// Add callgraph edge for each existing dynamic
		// "invoke"-mode call via that interface.
		for _, I := range r.interfaces(T) {
			sites, _ := r.invokeSites.At(I).([]ssa.CallInstruction)
			for _, site := range sites {
				r.addInvokeEdge(site, T)
			}
		}
	}

	// Precondition: T is not a method signature (*Signature with Recv()!=nil).
	// Recursive case: skip => don't call makeMethods(T).
	// Each package maintains its own set of types it has visited.

	var n *types.Named
	switch T := types.Unalias(T).(type) {
	case *types.Named:
		n = T
	case *types.Pointer:
		n, _ = types.Unalias(T.Elem()).(*types.Named)
	}
	if n != nil {
		owner := n.Obj().Pkg()
		if owner == nil {
			return // built-in error type
		}
	}

	// Recursion over signatures of each exported method.
	for method := range mset.Methods() {
		if method.Obj().Exported() {
			sig := method.Type().(*types.Signature)
			r.addRuntimeType(sig.Params(), true)  // skip the Tuple itself
			r.addRuntimeType(sig.Results(), true) // skip the Tuple itself
		}
	}

	switch t := T.(type) {
	case *types.Alias:
		panic("unreachable")

	case *types.Basic:
		// nop

	case *types.Interface:
		// nop---handled by recursion over method set.

	case *types.Pointer:
		r.addRuntimeType(t.Elem(), false)

	case *types.Slice:
		r.addRuntimeType(t.Elem(), false)

	case *types.Chan:
		r.addRuntimeType(t.Elem(), false)

	case *types.Map:
		r.addRuntimeType(t.Key(), false)
		r.addRuntimeType(t.Elem(), false)

	case *types.Signature:
		if t.Recv() != nil {
			panic(fmt.Sprintf("Signature %s has Recv %s", t, t.Recv()))
		}
		r.addRuntimeType(t.Params(), true)  // skip the Tuple itself
		r.addRuntimeType(t.Results(), true) // skip the Tuple itself

	case *types.Named:
		// A pointer-to-named type can be derived from a named
		// type via reflection.  It may have methods too.
		r.addRuntimeType(types.NewPointer(T), false)

		// Consider 'type T struct{S}' where S has methods.
		// Reflection provides no way to get from T to struct{S},
		// only to S, so the method set of struct{S} is unwanted,
		// so set 'skip' flag during recursion.
		r.addRuntimeType(t.Underlying(), true)

	case *types.Array:
		r.addRuntimeType(t.Elem(), false)

	case *types.Struct:
		for i, n := 0, t.NumFields(); i < n; i++ {
			r.addRuntimeType(t.Field(i).Type(), false)
		}

	case *types.Tuple:
		for i, n := 0, t.Len(); i < n; i++ {
			r.addRuntimeType(t.At(i).Type(), false)
		}

	default:
		panic(T)
	}
}

// fingerprint returns a bitmask with one bit set per method id,
// enabling 'implements' to quickly reject most candidates.
func fingerprint(mset *types.MethodSet) uint64 {
	var space [64]byte
	var mask uint64
	for method := range mset.Methods() {
		method := method.Obj()
		sig := method.Type().(*types.Signature)
		sum := crc32.ChecksumIEEE(fmt.Appendf(space[:], "%s/%d/%d",
			method.Id(),
			sig.Params().Len(),
			sig.Results().Len()))
		mask |= 1 << (sum % 64)
	}
	return mask
}

// implements reports whether types.Implements(cinfo.C, iinfo.I),
// but more efficiently.
func implements(cinfo *concreteTypeInfo, iinfo *interfaceTypeInfo) (got bool) {
	// The concrete type must have at least the methods
	// (bits) of the interface type. Use a bitwise subset
	// test to reject most candidates quickly.
	return iinfo.fprint & ^cinfo.fprint == 0 && types.Implements(cinfo.C, iinfo.I)
}


================================================
FILE: go/callgraph/rta/rta_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package rta_test

import (
	"fmt"
	"go/ast"
	"go/types"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/rta"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// TestRTA runs RTA on each testdata/*.txtar file containing a single
// go file in a single package or multiple files in different packages,
// and compares the results with the expectations expressed in the WANT
// comment.
func TestRTA(t *testing.T) {
	archivePaths := []string{
		"testdata/func.txtar",
		"testdata/generics.txtar",
		"testdata/iface.txtar",
		"testdata/reflectcall.txtar",
		"testdata/rtype.txtar",
		"testdata/multipkgs.txtar",
	}
	for _, archive := range archivePaths {
		t.Run(archive, func(t *testing.T) {
			ar, err := txtar.ParseFile(archive)
			if err != nil {
				t.Fatal(err)
			}

			pkgs := testfiles.LoadPackages(t, ar, "./...")

			// find the file which contains the expected result
			var f *ast.File
			for _, p := range pkgs {
				// We assume the packages have a single file or
				// the wanted result is in the first file of the main package.
				if p.Name == "main" {
					f = p.Syntax[0]
				}
			}
			if f == nil {
				t.Fatalf("failed to find the file with expected result within main package %s", archive)
			}

			prog, spkgs := ssautil.Packages(pkgs, ssa.SanityCheckFunctions|ssa.InstantiateGenerics)

			// find the main package to get functions for rta analysis
			var mainPkg *ssa.Package
			for _, sp := range spkgs {
				if sp.Pkg.Name() == "main" {
					mainPkg = sp
					break
				}
			}
			if mainPkg == nil {
				t.Fatalf("failed to find main ssa package %s", archive)
			}

			prog.Build()

			res := rta.Analyze([]*ssa.Function{
				mainPkg.Func("main"),
				mainPkg.Func("init"),
			}, true)

			check(t, f, mainPkg, res)
		})
	}
}

// check tests the RTA analysis results against the test expectations
// defined by a comment starting with a line "WANT:".
//
// The rest of the comment consists of lines of the following forms:
//
//	edge      <func> --kind--> <func>	# call graph edge
//	reachable <func>			# reachable function
//	rtype     <type>			# run-time type descriptor needed
//
// Each line asserts that an element is found in the given set, or, if
// the line is preceded by "!", that it is not in the set.
//
// Functions are notated as if by ssa.Function.String.
func check(t *testing.T, f *ast.File, pkg *ssa.Package, res *rta.Result) {
	tokFile := pkg.Prog.Fset.File(f.FileStart)

	// Find the WANT comment.
	expectation := func(f *ast.File) (string, int) {
		for _, c := range f.Comments {
			text := strings.TrimSpace(c.Text())
			if t, ok := strings.CutPrefix(text, "WANT:\n"); ok {
				return t, tokFile.Line(c.Pos())
			}
		}
		t.Fatalf("No WANT: comment in %s", tokFile.Name())
		return "", 0
	}
	want, linenum := expectation(f)

	// Parse the comment into three string-to-sense maps.
	var (
		wantEdge      = make(map[string]bool)
		wantReachable = make(map[string]bool)
		wantRtype     = make(map[string]bool)
	)
	for line := range strings.SplitSeq(want, "\n") {
		linenum++
		orig := line
		bad := func() {
			t.Fatalf("%s:%d: invalid assertion: %q", tokFile.Name(), linenum, orig)
		}

		line := strings.TrimSpace(line)
		if line == "" {
			continue // skip blanks
		}

		// A leading "!" negates the assertion.
		sense := true
		if rest, ok := strings.CutPrefix(line, "!"); ok {
			sense = false
			line = strings.TrimSpace(rest)
			if line == "" {
				bad()
			}
		}

		// Select the map.
		var want map[string]bool
		kind := strings.Fields(line)[0]
		switch kind {
		case "edge":
			want = wantEdge
		case "reachable":
			want = wantReachable
		case "rtype":
			want = wantRtype
		default:
			bad()
		}

		// Add expectation.
		str := strings.TrimSpace(line[len(kind):])
		want[str] = sense
	}

	type stringset = map[string]bool // (sets: values are true)

	// compare checks that got matches each assertion of the form
	// (str, sense) in want. The sense determines whether the test
	// is positive or negative.
	compare := func(kind string, got stringset, want map[string]bool) {
		ok := true
		for str, sense := range want {
			if got[str] != sense {
				ok = false
				if sense {
					t.Errorf("missing %s %q", kind, str)
				} else {
					t.Errorf("unwanted %s %q", kind, str)
				}
			}
		}

		// Print the actual output in expectation form.
		if !ok {
			var strs []string
			for s := range got {
				strs = append(strs, s)
			}
			sort.Strings(strs)
			var buf strings.Builder
			for _, str := range strs {
				fmt.Fprintf(&buf, "%s %s\n", kind, str)
			}
			t.Errorf("got:\n%s", &buf)
		}
	}

	// Check call graph edges.
	{
		got := make(stringset)
		callgraph.GraphVisitEdges(res.CallGraph, func(e *callgraph.Edge) error {
			edge := fmt.Sprintf("%s --%s--> %s",
				e.Caller.Func.RelString(pkg.Pkg),
				e.Description(),
				e.Callee.Func.RelString(pkg.Pkg))
			got[edge] = true
			return nil
		})
		compare("edge", got, wantEdge)
	}

	// Check reachable functions.
	{
		got := make(stringset)
		for f := range res.Reachable {
			got[f.RelString(pkg.Pkg)] = true
		}
		compare("reachable", got, wantReachable)
	}

	// Check runtime types.
	{
		got := make(stringset)
		res.RuntimeTypes.Iterate(func(key types.Type, value any) {
			if !value.(bool) { // accessible to reflection
				typ := types.TypeString(types.Unalias(key), types.RelativeTo(pkg.Pkg))
				got[typ] = true
			}
		})
		compare("rtype", got, wantRtype)
	}
}


================================================
FILE: go/callgraph/rta/testdata/func.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- func.go --
package main

// Test of dynamic function calls.
// No interfaces, so no runtime/reflect types.

func A1() {
	A2(0)
}

func A2(int) {} // not address-taken

func B() {} // unreachable

var (
	C = func(int) {}
	D = func(int) {}
)

func main() {
	A1()

	pfn := C
	pfn(0) // calls C and D but not A2 (same sig but not address-taken)
}

// WANT:
//
//  edge main --dynamic function call--> init$1
//  edge main --dynamic function call--> init$2
//
//  reachable A1
//  reachable A2
//  reachable init$1
//  reachable init$2
// !reachable B
//  reachable main

================================================
FILE: go/callgraph/rta/testdata/generics.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- generics.go --
package main

// Test of generic function calls.

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

func instantiated[X I](x X) {
	x.Foo()
}

var a A
var b B

func main() {
	instantiated[A](a) // static call
	instantiated[B](b) // static call

	local[C]().Foo()

	lambda[A]()()()
}

func local[X I]() I {
	var x X
	return x
}

type C struct{}

func (c C) Foo() {}

func lambda[X I]() func() func() {
	return func() func() {
		var x X
		return x.Foo
	}
}

// WANT:
//
//  edge (*C).Foo --static method call--> (C).Foo
//  edge (A).Foo$bound --static method call--> (A).Foo
//  edge instantiated[example.com.A] --static method call--> (A).Foo
//  edge instantiated[example.com.B] --static method call--> (B).Foo
//  edge main --dynamic method call--> (*C).Foo
//  edge main --dynamic function call--> (A).Foo$bound
//  edge main --dynamic method call--> (C).Foo
//  edge main --static function call--> instantiated[example.com.A]
//  edge main --static function call--> instantiated[example.com.B]
//  edge main --static function call--> lambda[example.com.A]
//  edge main --dynamic function call--> lambda[example.com.A]$1
//  edge main --static function call--> local[example.com.C]
//
//  reachable (*C).Foo
//  reachable (A).Foo
//  reachable (A).Foo$bound
//  reachable (B).Foo
//  reachable (C).Foo
//  reachable instantiated[example.com.A]
//  reachable instantiated[example.com.B]
//  reachable lambda[example.com.A]
//  reachable lambda[example.com.A]$1
//  reachable local[example.com.C]
//
//  rtype *C
//  rtype C


================================================
FILE: go/callgraph/rta/testdata/iface.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- iface.go --
package main

// Test of interface calls.

func use(interface{})

type A byte // instantiated but not a reflect type

func (A) f() {} // called directly
func (A) F() {} // unreachable

type B int // a reflect type

func (*B) f() {} // reachable via interface invoke
func (*B) F() {} // reachable: exported method of reflect type

type B2 int // a reflect type, and *B2 also

func (B2) f() {} // reachable via interface invoke
func (B2) g() {} // reachable: exported method of reflect type

type C string // not instantiated

func (C) f() {} // unreachable
func (C) F() {} // unreachable

type D uint // instantiated only in dead code

func (D) f() {} // unreachable
func (D) F() {} // unreachable

func main() {
	A(0).f()

	use(new(B))
	use(B2(0))

	var i interface {
		f()
	}
	i.f() // calls (*B).f, (*B2).f and (B2.f)

	live()
}

func live() {
	var j interface {
		f()
		g()
	}
	j.f() // calls (B2).f and (*B2).f but not (*B).f (no g method).
}

func dead() {
	use(D(0))
}

// WANT:
//
//  edge live --dynamic method call--> (*B2).f
//  edge live --dynamic method call--> (B2).f
//  edge main --dynamic method call--> (*B).f
//  edge main --dynamic method call--> (*B2).f
//  edge main --dynamic method call--> (B2).f
//
//  reachable (A).f
// !reachable (A).F
//  reachable (*B).f
//  reachable (*B).F
//  reachable (B2).f
// !reachable (B2).g
//  reachable (*B2).f
// !reachable (*B2).g
// !reachable (C).f
// !reachable (C).F
// !reachable (D).f
// !reachable (D).F
//  reachable main
//  reachable live
//  reachable use
// !reachable dead
//
// !rtype A
//  rtype *B
//  rtype *B2
//  rtype B
//  rtype B2
// !rtype C
// !rtype D


================================================
FILE: go/callgraph/rta/testdata/multipkgs.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- iface.go --
package main

import (
	"example.com/subpkg"
)

func use(interface{})

// Test of interface calls.

func main() {
	use(subpkg.A(0))
	use(new(subpkg.B))
	use(subpkg.B2(0))

	var i interface {
		F()
	}

	// assign an interface type with a function return interface value
	i = subpkg.NewInterfaceF()

	i.F()
}

func dead() {
	use(subpkg.D(0))
}

// WANT:
//
// edge (*example.com/subpkg.A).F --static method call--> (example.com/subpkg.A).F
// edge (*example.com/subpkg.B2).F --static method call--> (example.com/subpkg.B2).F
// edge (*example.com/subpkg.C).F --static method call--> (example.com/subpkg.C).F
// edge init --static function call--> example.com/subpkg.init
// edge main --dynamic method call--> (*example.com/subpkg.A).F
// edge main --dynamic method call--> (*example.com/subpkg.B).F
// edge main --dynamic method call--> (*example.com/subpkg.B2).F
// edge main --dynamic method call--> (*example.com/subpkg.C).F
// edge main --dynamic method call--> (example.com/subpkg.A).F
// edge main --dynamic method call--> (example.com/subpkg.B2).F
// edge main --dynamic method call--> (example.com/subpkg.C).F
// edge main --static function call--> example.com/subpkg.NewInterfaceF
// edge main --static function call--> use
//
// reachable (*example.com/subpkg.A).F
// reachable (*example.com/subpkg.B).F
// reachable (*example.com/subpkg.B2).F
// reachable (*example.com/subpkg.C).F
// reachable (example.com/subpkg.A).F
// !reachable (example.com/subpkg.B).F
// reachable (example.com/subpkg.B2).F
// reachable (example.com/subpkg.C).F
// reachable example.com/subpkg.NewInterfaceF
// reachable example.com/subpkg.init
// !reachable (*example.com/subpkg.D).F
// !reachable (example.com/subpkg.D).F
// reachable init
// reachable main
// reachable use
//
// rtype *example.com/subpkg.A
// rtype *example.com/subpkg.B
// rtype *example.com/subpkg.B2
// rtype *example.com/subpkg.C
// rtype example.com/subpkg.B
// rtype example.com/subpkg.A
// rtype example.com/subpkg.B2
// rtype example.com/subpkg.C
// !rtype example.com/subpkg.D

-- subpkg/impl.go --
package subpkg

type InterfaceF interface {
	F()
}

type A byte // instantiated but not a reflect type

func (A) F() {} // reachable: exported method of reflect type

type B int // a reflect type

func (*B) F() {} // reachable: exported method of reflect type

type B2 int // a reflect type, and *B2 also

func (B2) F() {} // reachable: exported method of reflect type

type C string

func (C) F() {} // reachable: exported by NewInterfaceF

func NewInterfaceF() InterfaceF {
	return C("")
}

type D uint // instantiated only in dead code

func (*D) F() {} // unreachable

================================================
FILE: go/callgraph/rta/testdata/reflectcall.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- reflectcall.go --
// Test of a reflective call to an address-taken function.
//
// Dynamically, this program executes both print statements.
// RTA should report the hello methods as reachable,
// even though there are no dynamic calls of type func(U)
// and the type T is not live.

package main

import "reflect"

type T int
type U int // to ensure the hello methods' signatures are unique

func (T) hello(U) { println("hello") }

type T2 int

func (T2) Hello(U, U) { println("T2.Hello") }

func main() {
	u := reflect.ValueOf(U(0))

	// reflective call to bound method closure T.hello
	reflect.ValueOf(T(0).hello).Call([]reflect.Value{u})

	// reflective call to exported method "Hello" of rtype T2.
	reflect.ValueOf(T2(0)).Method(0).Call([]reflect.Value{u, u})
}

// WANT:
//
//  edge (reflect.Value).Call --synthetic call--> (T).hello$bound
//  edge (T).hello$bound --static method call--> (T).hello
//  edge main --static function call--> reflect.ValueOf
//  edge main --static method call--> (reflect.Value).Call
//  edge (*T2).Hello --static method call--> (T2).Hello
//
//  reachable (T).hello
//  reachable (T).hello$bound
//  reachable (T2).Hello
//
// !rtype T
//  rtype T2
//  rtype U


================================================
FILE: go/callgraph/rta/testdata/rtype.txtar
================================================
-- go.mod --
module example.com
go 1.18

-- rtype.go --
package main

// Test of runtime types (types for which descriptors are needed).

func use(interface{})

type A byte // neither A nor byte are runtime types

type B struct{ x uint } // B and uint are runtime types, but not the struct

func main() {
	var x int // not a runtime type
	print(x)

	var y string // runtime type due to interface conversion
	use(y)

	use(struct{ uint64 }{}) // struct is a runtime type

	use(new(B)) // *B is a runtime type
}

// WANT:
//
//  reachable main
//  reachable use
//
// !rtype A
// !rtype struct{uint}
//  rtype *B
//  rtype B
//  rtype string
//  rtype struct{uint64}
//  rtype uint
//  rtype uint64
// !rtype int


================================================
FILE: go/callgraph/static/static.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package static computes the call graph of a Go program containing
// only static call edges.
package static

import (
	"go/types"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/ssa"
)

// CallGraph computes the static call graph of the specified program.
//
// The resulting graph includes:
// - all package-level functions;
// - all methods of package-level non-parameterized non-interface types;
// - pointer wrappers (*C).F for source-level methods C.F;
// - and all functions reachable from them following only static calls.
//
// It does not consider exportedness, nor treat main packages specially.
func CallGraph(prog *ssa.Program) *callgraph.Graph {
	cg := callgraph.New(nil)

	// Recursively follow all static calls.
	seen := make(map[int]bool) // node IDs already seen
	var visit func(fnode *callgraph.Node)
	visit = func(fnode *callgraph.Node) {
		if !seen[fnode.ID] {
			seen[fnode.ID] = true

			for _, b := range fnode.Func.Blocks {
				for _, instr := range b.Instrs {
					if site, ok := instr.(ssa.CallInstruction); ok {
						if g := site.Common().StaticCallee(); g != nil {
							gnode := cg.CreateNode(g)
							callgraph.AddEdge(fnode, site, gnode)
							visit(gnode)
						}
					}
				}
			}
		}
	}

	// If we were ever to redesign this function, we should allow
	// the caller to provide the set of root functions and just
	// perform the reachability step. This would allow them to
	// work forwards from main entry points:
	//
	// rootNames := []string{"init", "main"}
	// for _, main := range ssautil.MainPackages(prog.AllPackages()) {
	// 	for _, rootName := range rootNames {
	// 		visit(cg.CreateNode(main.Func(rootName)))
	// 	}
	// }
	//
	// or to control whether to include non-exported
	// functions/methods, wrapper methods, and so on.
	// Unfortunately that's not consistent with its historical
	// behavior and existing tests.
	//
	// The logic below is a slight simplification and
	// rationalization of ssautil.AllFunctions. (Having to include
	// (*T).F wrapper methods is unfortunate--they are not source
	// functions, and if they're reachable, they'll be in the
	// graph--but the existing tests will break without it.)

	methodsOf := func(T types.Type) {
		if !types.IsInterface(T) {
			mset := prog.MethodSets.MethodSet(T)
			for method := range mset.Methods() {
				visit(cg.CreateNode(prog.MethodValue(method)))
			}
		}
	}

	// Start from package-level symbols.
	for _, pkg := range prog.AllPackages() {
		for _, mem := range pkg.Members {
			switch mem := mem.(type) {
			case *ssa.Function:
				// package-level function
				visit(cg.CreateNode(mem))

			case *ssa.Type:
				// methods of package-level non-interface non-parameterized types
				if !types.IsInterface(mem.Type()) {
					if named, ok := mem.Type().(*types.Named); ok &&
						named.TypeParams() == nil {
						methodsOf(named)                   //  T
						methodsOf(types.NewPointer(named)) // *T
					}
				}
			}
		}
	}

	return cg
}


================================================
FILE: go/callgraph/static/static_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package static_test

import (
	"fmt"
	"reflect"
	"sort"
	"testing"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/static"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

const input = `

-- go.mod --
module x.io

go 1.22

-- p/p.go --
package main

type C int
func (C) f()

type I interface{f()}

func f() {
	p := func() {}
	g()
	p() // SSA constant propagation => static

	if unknown {
		p = h
	}
	p() // dynamic

	C(0).f()
}

func g() {
	var i I = C(0)
	i.f()
}

func h()

var unknown bool

func main() {
}
`

const genericsInput = `

-- go.mod --
module x.io

go 1.22

-- p/p.go --
package p

type I interface {
	F()
}

type A struct{}

func (a A) F() {}

type B struct{}

func (b B) F() {}

func instantiated[X I](x X) {
	x.F()
}

func Bar() {}

func f(h func(), a A, b B) {
	h()

	instantiated[A](a)
	instantiated[B](b)
}
`

func TestStatic(t *testing.T) {
	for _, e := range []struct {
		input string
		want  []string
	}{
		{input, []string{
			"(*C).f -> (C).f",
			"f -> (C).f",
			"f -> f$1",
			"f -> g",
		}},
		{genericsInput, []string{
			"(*A).F -> (A).F",
			"(*B).F -> (B).F",
			"f -> instantiated[x.io/p.A]",
			"f -> instantiated[x.io/p.B]",
			"instantiated[x.io/p.A] -> (A).F",
			"instantiated[x.io/p.B] -> (B).F",
		}},
	} {
		pkgs := testfiles.LoadPackages(t, txtar.Parse([]byte(e.input)), "./p")
		prog, _ := ssautil.Packages(pkgs, ssa.InstantiateGenerics)
		prog.Build()
		p := pkgs[0].Types

		cg := static.CallGraph(prog)

		var edges []string
		callgraph.GraphVisitEdges(cg, func(e *callgraph.Edge) error {
			edges = append(edges, fmt.Sprintf("%s -> %s",
				e.Caller.Func.RelString(p),
				e.Callee.Func.RelString(p)))
			return nil
		})
		sort.Strings(edges)

		if !reflect.DeepEqual(edges, e.want) {
			t.Errorf("Got edges %v, want %v", edges, e.want)
		}
	}
}


================================================
FILE: go/callgraph/util.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package callgraph

import "golang.org/x/tools/go/ssa"

// This file provides various utilities over call graphs, such as
// visitation and path search.

// CalleesOf returns a new set containing all direct callees of the
// caller node.
func CalleesOf(caller *Node) map[*Node]bool {
	callees := make(map[*Node]bool)
	for _, e := range caller.Out {
		callees[e.Callee] = true
	}
	return callees
}

// GraphVisitEdges visits all the edges in graph g in depth-first order.
// The edge function is called for each edge in postorder.  If it
// returns non-nil, visitation stops and GraphVisitEdges returns that
// value.
func GraphVisitEdges(g *Graph, edge func(*Edge) error) error {
	seen := make(map[*Node]bool)
	var visit func(n *Node) error
	visit = func(n *Node) error {
		if !seen[n] {
			seen[n] = true
			for _, e := range n.Out {
				if err := visit(e.Callee); err != nil {
					return err
				}
				if err := edge(e); err != nil {
					return err
				}
			}
		}
		return nil
	}
	for _, n := range g.Nodes {
		if err := visit(n); err != nil {
			return err
		}
	}
	return nil
}

// PathSearch finds an arbitrary path starting at node start and
// ending at some node for which isEnd() returns true.  On success,
// PathSearch returns the path as an ordered list of edges; on
// failure, it returns nil.
func PathSearch(start *Node, isEnd func(*Node) bool) []*Edge {
	stack := make([]*Edge, 0, 32)
	seen := make(map[*Node]bool)
	var search func(n *Node) []*Edge
	search = func(n *Node) []*Edge {
		if !seen[n] {
			seen[n] = true
			if isEnd(n) {
				return stack
			}
			for _, e := range n.Out {
				stack = append(stack, e) // push
				if found := search(e.Callee); found != nil {
					return found
				}
				stack = stack[:len(stack)-1] // pop
			}
		}
		return nil
	}
	return search(start)
}

// DeleteSyntheticNodes removes from call graph g all nodes for
// functions that do not correspond to source syntax. For historical
// reasons, nodes for g.Root and package initializers are always
// kept.
//
// As nodes are removed, edges are created to preserve the
// reachability relation of the remaining nodes.
func (g *Graph) DeleteSyntheticNodes() {
	// Measurements on the standard library and go.tools show that
	// resulting graph has ~15% fewer nodes and 4-8% fewer edges
	// than the input.
	//
	// Inlining a wrapper of in-degree m, out-degree n adds m*n
	// and removes m+n edges.  Since most wrappers are monomorphic
	// (n=1) this results in a slight reduction.  Polymorphic
	// wrappers (n>1), e.g. from embedding an interface value
	// inside a struct to satisfy some interface, cause an
	// increase in the graph, but they seem to be uncommon.

	// Hash all existing edges to avoid creating duplicates.
	edges := make(map[Edge]bool)
	for _, cgn := range g.Nodes {
		for _, e := range cgn.Out {
			edges[*e] = true
		}
	}
	for fn, cgn := range g.Nodes {
		if cgn == g.Root || isInit(cgn.Func) || fn.Syntax() != nil {
			continue // keep
		}
		for _, eIn := range cgn.In {
			for _, eOut := range cgn.Out {
				newEdge := Edge{eIn.Caller, eIn.Site, eOut.Callee}
				if edges[newEdge] {
					continue // don't add duplicate
				}
				AddEdge(eIn.Caller, eIn.Site, eOut.Callee)
				edges[newEdge] = true
			}
		}
		g.DeleteNode(cgn)
	}
}

func isInit(fn *ssa.Function) bool {
	return fn.Pkg != nil && fn.Pkg.Func("init") == fn
}

// DeleteNode removes node n and its edges from the graph g.
// (NB: not efficient for batch deletion.)
func (g *Graph) DeleteNode(n *Node) {
	n.deleteIns()
	n.deleteOuts()
	delete(g.Nodes, n.Func)
}

// deleteIns deletes all incoming edges to n.
func (n *Node) deleteIns() {
	for _, e := range n.In {
		removeOutEdge(e)
	}
	n.In = nil
}

// deleteOuts deletes all outgoing edges from n.
func (n *Node) deleteOuts() {
	for _, e := range n.Out {
		removeInEdge(e)
	}
	n.Out = nil
}

// removeOutEdge removes edge.Caller's outgoing edge 'edge'.
func removeOutEdge(edge *Edge) {
	caller := edge.Caller
	n := len(caller.Out)
	for i, e := range caller.Out {
		if e == edge {
			// Replace it with the final element and shrink the slice.
			caller.Out[i] = caller.Out[n-1]
			caller.Out[n-1] = nil // aid GC
			caller.Out = caller.Out[:n-1]
			return
		}
	}
	panic("edge not found: " + edge.String())
}

// removeInEdge removes edge.Callee's incoming edge 'edge'.
func removeInEdge(edge *Edge) {
	caller := edge.Callee
	n := len(caller.In)
	for i, e := range caller.In {
		if e == edge {
			// Replace it with the final element and shrink the slice.
			caller.In[i] = caller.In[n-1]
			caller.In[n-1] = nil // aid GC
			caller.In = caller.In[:n-1]
			return
		}
	}
	panic("edge not found: " + edge.String())
}


================================================
FILE: go/callgraph/vta/graph.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"fmt"
	"go/token"
	"go/types"
	"iter"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
)

// node interface for VTA nodes.
type node interface {
	Type() types.Type
	String() string
}

// constant node for VTA.
type constant struct {
	typ types.Type
}

func (c constant) Type() types.Type {
	return c.typ
}

func (c constant) String() string {
	return fmt.Sprintf("Constant(%v)", c.Type())
}

// pointer node for VTA.
type pointer struct {
	typ *types.Pointer
}

func (p pointer) Type() types.Type {
	return p.typ
}

func (p pointer) String() string {
	return fmt.Sprintf("Pointer(%v)", p.Type())
}

// mapKey node for VTA, modeling reachable map key types.
type mapKey struct {
	typ types.Type
}

func (mk mapKey) Type() types.Type {
	return mk.typ
}

func (mk mapKey) String() string {
	return fmt.Sprintf("MapKey(%v)", mk.Type())
}

// mapValue node for VTA, modeling reachable map value types.
type mapValue struct {
	typ types.Type
}

func (mv mapValue) Type() types.Type {
	return mv.typ
}

func (mv mapValue) String() string {
	return fmt.Sprintf("MapValue(%v)", mv.Type())
}

// sliceElem node for VTA, modeling reachable slice and array element types.
type sliceElem struct {
	typ types.Type
}

func (s sliceElem) Type() types.Type {
	return s.typ
}

func (s sliceElem) String() string {
	return fmt.Sprintf("Slice([]%v)", s.Type())
}

// channelElem node for VTA, modeling reachable channel element types.
type channelElem struct {
	typ types.Type
}

func (c channelElem) Type() types.Type {
	return c.typ
}

func (c channelElem) String() string {
	return fmt.Sprintf("Channel(chan %v)", c.Type())
}

// field node for VTA.
type field struct {
	StructType types.Type
	index      int // index of the field in the struct
}

func (f field) Type() types.Type {
	s := typeparams.CoreType(f.StructType).(*types.Struct)
	return s.Field(f.index).Type()
}

func (f field) String() string {
	s := typeparams.CoreType(f.StructType).(*types.Struct)
	return fmt.Sprintf("Field(%v:%s)", f.StructType, s.Field(f.index).Name())
}

// global node for VTA.
type global struct {
	val *ssa.Global
}

func (g global) Type() types.Type {
	return g.val.Type()
}

func (g global) String() string {
	return fmt.Sprintf("Global(%s)", g.val.Name())
}

// local node for VTA modeling local variables
// and function/method parameters.
type local struct {
	val ssa.Value
}

func (l local) Type() types.Type {
	return l.val.Type()
}

func (l local) String() string {
	return fmt.Sprintf("Local(%s)", l.val.Name())
}

// indexedLocal node for VTA node. Models indexed locals
// related to the ssa extract instructions.
type indexedLocal struct {
	val   ssa.Value
	index int
	typ   types.Type
}

func (i indexedLocal) Type() types.Type {
	return i.typ
}

func (i indexedLocal) String() string {
	return fmt.Sprintf("Local(%s[%d])", i.val.Name(), i.index)
}

// function node for VTA.
type function struct {
	f *ssa.Function
}

func (f function) Type() types.Type {
	return f.f.Type()
}

func (f function) String() string {
	return fmt.Sprintf("Function(%s)", f.f.Name())
}

// resultVar represents the result
// variable of a function, whether
// named or not.
type resultVar struct {
	f     *ssa.Function
	index int // valid index into result var tuple
}

func (o resultVar) Type() types.Type {
	return o.f.Signature.Results().At(o.index).Type()
}

func (o resultVar) String() string {
	v := o.f.Signature.Results().At(o.index)
	if n := v.Name(); n != "" {
		return fmt.Sprintf("Return(%s[%s])", o.f.Name(), n)
	}
	return fmt.Sprintf("Return(%s[%d])", o.f.Name(), o.index)
}

// nestedPtrInterface node represents all references and dereferences
// of locals and globals that have a nested pointer to interface type.
// We merge such constructs into a single node for simplicity and without
// much precision sacrifice as such variables are rare in practice. Both
// a and b would be represented as the same PtrInterface(I) node in:
//
//	type I interface
//	var a ***I
//	var b **I
type nestedPtrInterface struct {
	typ types.Type
}

func (l nestedPtrInterface) Type() types.Type {
	return l.typ
}

func (l nestedPtrInterface) String() string {
	return fmt.Sprintf("PtrInterface(%v)", l.typ)
}

// nestedPtrFunction node represents all references and dereferences of locals
// and globals that have a nested pointer to function type. We merge such
// constructs into a single node for simplicity and without much precision
// sacrifice as such variables are rare in practice. Both a and b would be
// represented as the same PtrFunction(func()) node in:
//
//	var a *func()
//	var b **func()
type nestedPtrFunction struct {
	typ types.Type
}

func (p nestedPtrFunction) Type() types.Type {
	return p.typ
}

func (p nestedPtrFunction) String() string {
	return fmt.Sprintf("PtrFunction(%v)", p.typ)
}

// panicArg models types of all arguments passed to panic.
type panicArg struct{}

func (p panicArg) Type() types.Type {
	return nil
}

func (p panicArg) String() string {
	return "Panic"
}

// recoverReturn models types of all return values of recover().
type recoverReturn struct{}

func (r recoverReturn) Type() types.Type {
	return nil
}

func (r recoverReturn) String() string {
	return "Recover"
}

type empty = struct{}

// idx is an index representing a unique node in a vtaGraph.
type idx int

// vtaGraph remembers for each VTA node the set of its successors.
// Tailored for VTA, hence does not support singleton (sub)graphs.
type vtaGraph struct {
	m    []map[idx]empty // m[i] has the successors for the node with index i.
	idx  map[node]idx    // idx[n] is the index for the node n.
	node []node          // node[i] is the node with index i.
}

func (g *vtaGraph) numNodes() int {
	return len(g.idx)
}

func (g *vtaGraph) successors(x idx) iter.Seq[idx] {
	return func(yield func(y idx) bool) {
		for y := range g.m[x] {
			if !yield(y) {
				return
			}
		}
	}
}

// addEdge adds an edge x->y to the graph.
func (g *vtaGraph) addEdge(x, y node) {
	if g.idx == nil {
		g.idx = make(map[node]idx)
	}
	lookup := func(n node) idx {
		i, ok := g.idx[n]
		if !ok {
			i = idx(len(g.idx))
			g.m = append(g.m, nil)
			g.idx[n] = i
			g.node = append(g.node, n)
		}
		return i
	}
	a := lookup(x)
	b := lookup(y)
	succs := g.m[a]
	if succs == nil {
		succs = make(map[idx]empty)
		g.m[a] = succs
	}
	succs[b] = empty{}
}

// typePropGraph builds a VTA graph for a set of `funcs` and initial
// `callgraph` needed to establish interprocedural edges. Returns the
// graph and a map for unique type representatives.
func typePropGraph(funcs map[*ssa.Function]bool, callees calleesFunc) (*vtaGraph, *typeutil.Map) {
	b := builder{callees: callees}
	b.visit(funcs)
	b.callees = nil // ensure callees is not pinned by pointers to other fields of b.
	return &b.graph, &b.canon
}

// Data structure responsible for linearly traversing the
// code and building a VTA graph.
type builder struct {
	graph   vtaGraph
	callees calleesFunc // initial call graph for creating flows at unresolved call sites.

	// Specialized type map for canonicalization of types.Type.
	// Semantically equivalent types can have different implementations,
	// i.e., they are different pointer values. The map allows us to
	// have one unique representative. The keys are fixed and from the
	// client perspective they are types. The values in our case are
	// types too, in particular type representatives. Each value is a
	// pointer so this map is not expected to take much memory.
	canon typeutil.Map
}

func (b *builder) visit(funcs map[*ssa.Function]bool) {
	// Add the fixed edge Panic -> Recover
	b.graph.addEdge(panicArg{}, recoverReturn{})

	for f, in := range funcs {
		if in {
			b.fun(f)
		}
	}
}

func (b *builder) fun(f *ssa.Function) {
	for _, bl := range f.Blocks {
		for _, instr := range bl.Instrs {
			b.instr(instr)
		}
	}
}

func (b *builder) instr(instr ssa.Instruction) {
	switch i := instr.(type) {
	case *ssa.Store:
		b.addInFlowAliasEdges(b.nodeFromVal(i.Addr), b.nodeFromVal(i.Val))
	case *ssa.MakeInterface:
		b.addInFlowEdge(b.nodeFromVal(i.X), b.nodeFromVal(i))
	case *ssa.MakeClosure:
		b.closure(i)
	case *ssa.UnOp:
		b.unop(i)
	case *ssa.Phi:
		b.phi(i)
	case *ssa.ChangeInterface:
		// Although in change interface a := A(b) command a and b are
		// the same object, the only interesting flow happens when A
		// is an interface. We create flow b -> a, but omit a -> b.
		// The latter flow is not needed: if a gets assigned concrete
		// type later on, that cannot be propagated back to b as b
		// is a separate variable. The a -> b flow can happen when
		// A is a pointer to interface, but then the command is of
		// type ChangeType, handled below.
		b.addInFlowEdge(b.nodeFromVal(i.X), b.nodeFromVal(i))
	case *ssa.ChangeType:
		// change type command a := A(b) results in a and b being the
		// same value. For concrete type A, there is no interesting flow.
		//
		// When A is an interface, most interface casts are handled
		// by the ChangeInterface instruction. The relevant case here is
		// when converting a pointer to an interface type. This can happen
		// when the underlying interfaces have the same method set.
		//
		//	type I interface{ foo() }
		//	type J interface{ foo() }
		//	var b *I
		//	a := (*J)(b)
		//
		// When this happens we add flows between a <--> b.
		b.addInFlowAliasEdges(b.nodeFromVal(i), b.nodeFromVal(i.X))
	case *ssa.TypeAssert:
		b.tassert(i)
	case *ssa.Extract:
		b.extract(i)
	case *ssa.Field:
		b.field(i)
	case *ssa.FieldAddr:
		b.fieldAddr(i)
	case *ssa.Send:
		b.send(i)
	case *ssa.Select:
		b.selekt(i)
	case *ssa.Index:
		b.index(i)
	case *ssa.IndexAddr:
		b.indexAddr(i)
	case *ssa.Lookup:
		b.lookup(i)
	case *ssa.MapUpdate:
		b.mapUpdate(i)
	case *ssa.Next:
		b.next(i)
	case ssa.CallInstruction:
		b.call(i)
	case *ssa.Panic:
		b.panic(i)
	case *ssa.Return:
		b.rtrn(i)
	case *ssa.MakeChan, *ssa.MakeMap, *ssa.MakeSlice, *ssa.BinOp,
		*ssa.Alloc, *ssa.DebugRef, *ssa.Convert, *ssa.Jump, *ssa.If,
		*ssa.Slice, *ssa.SliceToArrayPointer, *ssa.Range, *ssa.RunDefers:
		// No interesting flow here.
		// Notes on individual instructions:
		// SliceToArrayPointer: t1 = slice to array pointer *[4]T <- []T (t0)
		// No interesting flow as sliceArrayElem(t1) == sliceArrayElem(t0).
		return
	case *ssa.MultiConvert:
		b.multiconvert(i)
	default:
		panic(fmt.Sprintf("unsupported instruction %v\n", instr))
	}
}

func (b *builder) unop(u *ssa.UnOp) {
	switch u.Op {
	case token.MUL:
		// Multiplication operator * is used here as a dereference operator.
		b.addInFlowAliasEdges(b.nodeFromVal(u), b.nodeFromVal(u.X))
	case token.ARROW:
		t := typeparams.CoreType(u.X.Type()).(*types.Chan).Elem()
		b.addInFlowAliasEdges(b.nodeFromVal(u), channelElem{typ: t})
	default:
		// There is no interesting type flow otherwise.
	}
}

func (b *builder) phi(p *ssa.Phi) {
	for _, edge := range p.Edges {
		b.addInFlowAliasEdges(b.nodeFromVal(p), b.nodeFromVal(edge))
	}
}

func (b *builder) tassert(a *ssa.TypeAssert) {
	if !a.CommaOk {
		b.addInFlowEdge(b.nodeFromVal(a.X), b.nodeFromVal(a))
		return
	}
	// The case where a is <a.AssertedType, bool> register so there
	// is a flow from a.X to a[0]. Here, a[0] is represented as an
	// indexedLocal: an entry into local tuple register a at index 0.
	tup := a.Type().(*types.Tuple)
	t := tup.At(0).Type()

	local := indexedLocal{val: a, typ: t, index: 0}
	b.addInFlowEdge(b.nodeFromVal(a.X), local)
}

// extract instruction t1 := t2[i] generates flows between t2[i]
// and t1 where the source is indexed local representing a value
// from tuple register t2 at index i and the target is t1.
func (b *builder) extract(e *ssa.Extract) {
	tup := e.Tuple.Type().(*types.Tuple)
	t := tup.At(e.Index).Type()

	local := indexedLocal{val: e.Tuple, typ: t, index: e.Index}
	b.addInFlowAliasEdges(b.nodeFromVal(e), local)
}

func (b *builder) field(f *ssa.Field) {
	fnode := field{StructType: f.X.Type(), index: f.Field}
	b.addInFlowEdge(fnode, b.nodeFromVal(f))
}

func (b *builder) fieldAddr(f *ssa.FieldAddr) {
	t := typeparams.CoreType(f.X.Type()).(*types.Pointer).Elem()

	// Since we are getting pointer to a field, make a bidirectional edge.
	fnode := field{StructType: t, index: f.Field}
	b.addInFlowEdge(fnode, b.nodeFromVal(f))
	b.addInFlowEdge(b.nodeFromVal(f), fnode)
}

func (b *builder) send(s *ssa.Send) {
	t := typeparams.CoreType(s.Chan.Type()).(*types.Chan).Elem()
	b.addInFlowAliasEdges(channelElem{typ: t}, b.nodeFromVal(s.X))
}

// selekt generates flows for select statement
//
//	a = select blocking/nonblocking [c_1 <- t_1, c_2 <- t_2, ..., <- o_1, <- o_2, ...]
//
// between receiving channel registers c_i and corresponding input register t_i. Further,
// flows are generated between o_i and a[2 + i]. Note that a is a tuple register of type
// <int, bool, r_1, r_2, ...> where the type of r_i is the element type of channel o_i.
func (b *builder) selekt(s *ssa.Select) {
	recvIndex := 0
	for _, state := range s.States {
		t := typeparams.CoreType(state.Chan.Type()).(*types.Chan).Elem()

		if state.Dir == types.SendOnly {
			b.addInFlowAliasEdges(channelElem{typ: t}, b.nodeFromVal(state.Send))
		} else {
			// state.Dir == RecvOnly by definition of select instructions.
			tupEntry := indexedLocal{val: s, typ: t, index: 2 + recvIndex}
			b.addInFlowAliasEdges(tupEntry, channelElem{typ: t})
			recvIndex++
		}
	}
}

// index instruction a := b[c] on slices creates flows between a and
// SliceElem(t) flow where t is an interface type of c. Arrays and
// slice elements are both modeled as SliceElem.
func (b *builder) index(i *ssa.Index) {
	et := sliceArrayElem(i.X.Type())
	b.addInFlowAliasEdges(b.nodeFromVal(i), sliceElem{typ: et})
}

// indexAddr instruction a := &b[c] fetches address of a index
// into the field so we create bidirectional flow a <-> SliceElem(t)
// where t is an interface type of c. Arrays and slice elements are
// both modeled as SliceElem.
func (b *builder) indexAddr(i *ssa.IndexAddr) {
	et := sliceArrayElem(i.X.Type())
	b.addInFlowEdge(sliceElem{typ: et}, b.nodeFromVal(i))
	b.addInFlowEdge(b.nodeFromVal(i), sliceElem{typ: et})
}

// lookup handles map query commands a := m[b] where m is of type
// map[...]V and V is an interface. It creates flows between `a`
// and MapValue(V).
func (b *builder) lookup(l *ssa.Lookup) {
	t, ok := l.X.Type().Underlying().(*types.Map)
	if !ok {
		// No interesting flows for string lookups.
		return
	}

	if !l.CommaOk {
		b.addInFlowAliasEdges(b.nodeFromVal(l), mapValue{typ: t.Elem()})
	} else {
		i := indexedLocal{val: l, typ: t.Elem(), index: 0}
		b.addInFlowAliasEdges(i, mapValue{typ: t.Elem()})
	}
}

// mapUpdate handles map update commands m[b] = a where m is of type
// map[K]V and K and V are interfaces. It creates flows between `a`
// and MapValue(V) as well as between MapKey(K) and `b`.
func (b *builder) mapUpdate(u *ssa.MapUpdate) {
	t, ok := u.Map.Type().Underlying().(*types.Map)
	if !ok {
		// No interesting flows for string updates.
		return
	}

	b.addInFlowAliasEdges(mapKey{typ: t.Key()}, b.nodeFromVal(u.Key))
	b.addInFlowAliasEdges(mapValue{typ: t.Elem()}, b.nodeFromVal(u.Value))
}

// next instruction <ok, key, value> := next r, where r
// is a range over map or string generates flow between
// key and MapKey as well value and MapValue nodes.
func (b *builder) next(n *ssa.Next) {
	if n.IsString {
		return
	}
	tup := n.Type().(*types.Tuple)
	kt := tup.At(1).Type()
	vt := tup.At(2).Type()

	b.addInFlowAliasEdges(indexedLocal{val: n, typ: kt, index: 1}, mapKey{typ: kt})
	b.addInFlowAliasEdges(indexedLocal{val: n, typ: vt, index: 2}, mapValue{typ: vt})
}

// addInFlowAliasEdges adds an edge r -> l to b.graph if l is a node that can
// have an inflow, i.e., a node that represents an interface or an unresolved
// function value. Similarly for the edge l -> r with an additional condition
// of that l and r can potentially alias.
func (b *builder) addInFlowAliasEdges(l, r node) {
	b.addInFlowEdge(r, l)

	if canAlias(l, r) {
		b.addInFlowEdge(l, r)
	}
}

func (b *builder) closure(c *ssa.MakeClosure) {
	f := c.Fn.(*ssa.Function)
	b.addInFlowEdge(function{f: f}, b.nodeFromVal(c))

	for i, fv := range f.FreeVars {
		b.addInFlowAliasEdges(b.nodeFromVal(fv), b.nodeFromVal(c.Bindings[i]))
	}
}

// panic creates a flow from arguments to panic instructions to return
// registers of all recover statements in the program. Introduces a
// global panic node Panic and
//  1. for every panic statement p: add p -> Panic
//  2. for every recover statement r: add Panic -> r (handled in call)
//
// TODO(zpavlinovic): improve precision by explicitly modeling how panic
// values flow from callees to callers and into deferred recover instructions.
func (b *builder) panic(p *ssa.Panic) {
	// Panics often have, for instance, strings as arguments which do
	// not create interesting flows.
	if !canHaveMethods(p.X.Type()) {
		return
	}

	b.addInFlowEdge(b.nodeFromVal(p.X), panicArg{})
}

// call adds flows between arguments/parameters and return values/registers
// for both static and dynamic calls, as well as go and defer calls.
func (b *builder) call(c ssa.CallInstruction) {
	// When c is r := recover() call register instruction, we add Recover -> r.
	if bf, ok := c.Common().Value.(*ssa.Builtin); ok && bf.Name() == "recover" {
		if v, ok := c.(ssa.Value); ok {
			b.addInFlowEdge(recoverReturn{}, b.nodeFromVal(v))
		}
		return
	}

	for f := range siteCallees(c, b.callees) {
		addArgumentFlows(b, c, f)

		site, ok := c.(ssa.Value)
		if !ok {
			continue // go or defer
		}

		results := f.Signature.Results()
		if results.Len() == 1 {
			// When there is only one return value, the destination register does not
			// have a tuple type.
			b.addInFlowEdge(resultVar{f: f, index: 0}, b.nodeFromVal(site))
		} else {
			tup := site.Type().(*types.Tuple)
			for i := 0; i < results.Len(); i++ {
				local := indexedLocal{val: site, typ: tup.At(i).Type(), index: i}
				b.addInFlowEdge(resultVar{f: f, index: i}, local)
			}
		}
	}
}

func addArgumentFlows(b *builder, c ssa.CallInstruction, f *ssa.Function) {
	// When f has no parameters (including receiver), there is no type
	// flow here. Also, f's body and parameters might be missing, such
	// as when vta is used within the golang.org/x/tools/go/analysis
	// framework (see github.com/golang/go/issues/50670).
	if len(f.Params) == 0 {
		return
	}
	cc := c.Common()
	if cc.Method != nil {
		// In principle we don't add interprocedural flows for receiver
		// objects. At a call site, the receiver object is interface
		// while the callee object is concrete. The flow from interface
		// to concrete type in general does not make sense. The exception
		// is when the concrete type is a named function type (see #57756).
		//
		// The flow other way around would bake in information from the
		// initial call graph.
		if isFunction(f.Params[0].Type()) {
			b.addInFlowEdge(b.nodeFromVal(cc.Value), b.nodeFromVal(f.Params[0]))
		}
	}

	offset := 0
	if cc.Method != nil {
		offset = 1
	}
	for i, v := range cc.Args {
		// Parameters of f might not be available, as in the case
		// when vta is used within the golang.org/x/tools/go/analysis
		// framework (see github.com/golang/go/issues/50670).
		//
		// TODO: investigate other cases of missing body and parameters
		if len(f.Params) <= i+offset {
			return
		}
		b.addInFlowAliasEdges(b.nodeFromVal(f.Params[i+offset]), b.nodeFromVal(v))
	}
}

// rtrn creates flow edges from the operands of the return
// statement to the result variables of the enclosing function.
func (b *builder) rtrn(r *ssa.Return) {
	for i, rs := range r.Results {
		b.addInFlowEdge(b.nodeFromVal(rs), resultVar{f: r.Parent(), index: i})
	}
}

func (b *builder) multiconvert(c *ssa.MultiConvert) {
	// TODO(zpavlinovic): decide what to do on MultiConvert long term.
	// TODO(zpavlinovic): add unit tests.
	typeSetOf := func(typ types.Type) []*types.Term {
		// This is a adaptation of x/exp/typeparams.NormalTerms which x/tools cannot depend on.
		var terms []*types.Term
		var err error
		switch typ := types.Unalias(typ).(type) {
		case *types.TypeParam:
			terms, err = typeparams.StructuralTerms(typ)
		case *types.Union:
			terms, err = typeparams.UnionTermSet(typ)
		case *types.Interface:
			terms, err = typeparams.InterfaceTermSet(typ)
		default:
			// Common case.
			// Specializing the len=1 case to avoid a slice
			// had no measurable space/time benefit.
			terms = []*types.Term{types.NewTerm(false, typ)}
		}

		if err != nil {
			return nil
		}
		return terms
	}
	// isValuePreserving returns true if a conversion from ut_src to
	// ut_dst is value-preserving, i.e. just a change of type.
	// Precondition: neither argument is a named or alias type.
	isValuePreserving := func(ut_src, ut_dst types.Type) bool {
		// Identical underlying types?
		if types.IdenticalIgnoreTags(ut_dst, ut_src) {
			return true
		}

		switch ut_dst.(type) {
		case *types.Chan:
			// Conversion between channel types?
			_, ok := ut_src.(*types.Chan)
			return ok

		case *types.Pointer:
			// Conversion between pointers with identical base types?
			_, ok := ut_src.(*types.Pointer)
			return ok
		}
		return false
	}
	dst_terms := typeSetOf(c.Type())
	src_terms := typeSetOf(c.X.Type())
	for _, s := range src_terms {
		us := s.Type().Underlying()
		for _, d := range dst_terms {
			ud := d.Type().Underlying()
			if isValuePreserving(us, ud) {
				// This is equivalent to a ChangeType.
				b.addInFlowAliasEdges(b.nodeFromVal(c), b.nodeFromVal(c.X))
				return
			}
			// This is equivalent to either: SliceToArrayPointer,,
			// SliceToArrayPointer+Deref, Size 0 Array constant, or a Convert.
		}
	}
}

// addInFlowEdge adds s -> d to g if d is node that can have an inflow, i.e., a node
// that represents an interface or an unresolved function value. Otherwise, there
// is no interesting type flow so the edge is omitted.
func (b *builder) addInFlowEdge(s, d node) {
	if hasInFlow(d) {
		b.graph.addEdge(b.representative(s), b.representative(d))
	}
}

// Creates const, pointer, global, func, and local nodes based on register instructions.
func (b *builder) nodeFromVal(val ssa.Value) node {
	if p, ok := types.Unalias(val.Type()).(*types.Pointer); ok && !types.IsInterface(p.Elem()) && !isFunction(p.Elem()) {
		// Nested pointer to interfaces are modeled as a special
		// nestedPtrInterface node.
		if i := interfaceUnderPtr(p.Elem()); i != nil {
			return nestedPtrInterface{typ: i}
		}
		// The same goes for nested function types.
		if f := functionUnderPtr(p.Elem()); f != nil {
			return nestedPtrFunction{typ: f}
		}
		return pointer{typ: p}
	}

	switch v := val.(type) {
	case *ssa.Const:
		return constant{typ: val.Type()}
	case *ssa.Global:
		return global{val: v}
	case *ssa.Function:
		return function{f: v}
	case *ssa.Parameter, *ssa.FreeVar, ssa.Instruction:
		// ssa.Param, ssa.FreeVar, and a specific set of "register" instructions,
		// satisfying the ssa.Value interface, can serve as local variables.
		return local{val: v}
	default:
		panic(fmt.Errorf("unsupported value %v in node creation", val))
	}
}

// representative returns a unique representative for node `n`. Since
// semantically equivalent types can have different implementations,
// this method guarantees the same implementation is always used.
func (b *builder) representative(n node) node {
	if n.Type() == nil {
		// panicArg and recoverReturn do not have
		// types and are unique by definition.
		return n
	}
	t := canonicalize(n.Type(), &b.canon)

	switch i := n.(type) {
	case constant:
		return constant{typ: t}
	case pointer:
		return pointer{typ: t.(*types.Pointer)}
	case sliceElem:
		return sliceElem{typ: t}
	case mapKey:
		return mapKey{typ: t}
	case mapValue:
		return mapValue{typ: t}
	case channelElem:
		return channelElem{typ: t}
	case nestedPtrInterface:
		return nestedPtrInterface{typ: t}
	case nestedPtrFunction:
		return nestedPtrFunction{typ: t}
	case field:
		return field{StructType: canonicalize(i.StructType, &b.canon), index: i.index}
	case indexedLocal:
		return indexedLocal{typ: t, val: i.val, index: i.index}
	case local, global, panicArg, recoverReturn, function, resultVar:
		return n
	default:
		panic(fmt.Errorf("canonicalizing unrecognized node %v", n))
	}
}

// canonicalize returns a type representative of `t` unique subject
// to type map `canon`.
func canonicalize(t types.Type, canon *typeutil.Map) types.Type {
	rep := canon.At(t)
	if rep != nil {
		return rep.(types.Type)
	}
	canon.Set(t, t)
	return t
}


================================================
FILE: go/callgraph/vta/graph_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"fmt"
	"go/types"
	"reflect"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

func TestNodeInterface(t *testing.T) {
	// Since ssa package does not allow explicit creation of ssa
	// values, we use the values from the program testdata/src/simple.go:
	//   - basic type int
	//   - struct X with two int fields a and b
	//   - global variable "gl"
	//   - "foo" function
	//   - "main" function and its
	//   - first register instruction t0 := *gl
	prog, _, err := testProg(t, "testdata/src/simple.go", ssa.BuilderMode(0))
	if err != nil {
		t.Fatalf("couldn't load testdata/src/simple.go program: %v", err)
	}

	pkg := prog.AllPackages()[0]
	main := pkg.Func("main")
	foo := pkg.Func("foo")
	reg := firstRegInstr(main) // t0 := *gl
	X := pkg.Type("X").Type()
	gl := pkg.Var("gl")
	glPtrType, ok := types.Unalias(gl.Type()).(*types.Pointer)
	if !ok {
		t.Fatalf("could not cast gl variable to pointer type")
	}
	bint := glPtrType.Elem()

	pint := types.NewPointer(bint)
	i := types.NewInterface(nil, nil)

	voidFunc := main.Signature.Underlying()

	for _, test := range []struct {
		n node
		s string
		t types.Type
	}{
		{constant{typ: bint}, "Constant(int)", bint},
		{pointer{typ: pint}, "Pointer(*int)", pint},
		{mapKey{typ: bint}, "MapKey(int)", bint},
		{mapValue{typ: pint}, "MapValue(*int)", pint},
		{sliceElem{typ: bint}, "Slice([]int)", bint},
		{channelElem{typ: pint}, "Channel(chan *int)", pint},
		{field{StructType: X, index: 0}, "Field(testdata.X:a)", bint},
		{field{StructType: X, index: 1}, "Field(testdata.X:b)", bint},
		{global{val: gl}, "Global(gl)", gl.Type()},
		{local{val: reg}, "Local(t0)", bint},
		{indexedLocal{val: reg, typ: X, index: 0}, "Local(t0[0])", X},
		{function{f: main}, "Function(main)", voidFunc},
		{resultVar{f: foo, index: 0}, "Return(foo[r])", bint},
		{nestedPtrInterface{typ: i}, "PtrInterface(interface{})", i},
		{nestedPtrFunction{typ: voidFunc}, "PtrFunction(func())", voidFunc},
		{panicArg{}, "Panic", nil},
		{recoverReturn{}, "Recover", nil},
	} {
		if removeModulePrefix(test.s) != removeModulePrefix(test.n.String()) {
			t.Errorf("want %s; got %s", removeModulePrefix(test.s), removeModulePrefix(test.n.String()))
		}
		if test.t != test.n.Type() {
			t.Errorf("want %s; got %s", test.t, test.n.Type())
		}
	}
}

// removeModulePrefix removes the "x.io/" module name prefix throughout s.
// (It is added by testProg.)
func removeModulePrefix(s string) string {
	return strings.ReplaceAll(s, "x.io/", "")
}

func TestVtaGraph(t *testing.T) {
	// Get the basic type int from a real program.
	prog, _, err := testProg(t, "testdata/src/simple.go", ssa.BuilderMode(0))
	if err != nil {
		t.Fatalf("couldn't load testdata/src/simple.go program: %v", err)
	}

	glPtrType, ok := prog.AllPackages()[0].Var("gl").Type().(*types.Pointer)
	if !ok {
		t.Fatalf("could not cast gl variable to pointer type")
	}
	bint := glPtrType.Elem()

	n1 := constant{typ: bint}
	n2 := pointer{typ: types.NewPointer(bint)}
	n3 := mapKey{typ: types.NewMap(bint, bint)}
	n4 := mapValue{typ: types.NewMap(bint, bint)}

	// Create graph
	//   n1   n2
	//    \  / /
	//     n3 /
	//     | /
	//     n4
	var g vtaGraph
	g.addEdge(n1, n3)
	g.addEdge(n2, n3)
	g.addEdge(n3, n4)
	g.addEdge(n2, n4)
	// for checking duplicates
	g.addEdge(n1, n3)

	want := vtaGraph{
		m: []map[idx]empty{
			map[idx]empty{1: empty{}},
			map[idx]empty{3: empty{}},
			map[idx]empty{1: empty{}, 3: empty{}},
			nil,
		},
		idx: map[node]idx{
			n1: 0,
			n3: 1,
			n2: 2,
			n4: 3,
		},
		node: []node{n1, n3, n2, n4},
	}

	if !reflect.DeepEqual(want, g) {
		t.Errorf("want %v; got %v", want, g)
	}

	for _, test := range []struct {
		n node
		l int
	}{
		{n1, 1},
		{n2, 2},
		{n3, 1},
		{n4, 0},
	} {
		sl := 0
		for range g.successors(g.idx[test.n]) {
			sl++
		}
		if sl != test.l {
			t.Errorf("want %d successors; got %d", test.l, sl)
		}
	}
}

// vtaGraphStr stringifies vtaGraph into a list of strings
// where each string represents an edge set of the format
// node -> succ_1, ..., succ_n. succ_1, ..., succ_n are
// sorted in alphabetical order.
func vtaGraphStr(g *vtaGraph) []string {
	var vgs []string
	for n := 0; n < g.numNodes(); n++ {
		var succStr []string
		for s := range g.successors(idx(n)) {
			succStr = append(succStr, g.node[s].String())
		}

		sort.Strings(succStr)
		entry := fmt.Sprintf("%v -> %v", g.node[n].String(), strings.Join(succStr, ", "))
		vgs = append(vgs, removeModulePrefix(entry))
	}
	return vgs
}

// setdiff returns the set difference of `X-Y` or {s | s ∈ X, s ∉ Y }.
func setdiff(X, Y []string) []string {
	y := make(map[string]bool)
	var delta []string
	for _, s := range Y {
		y[s] = true
	}

	for _, s := range X {
		if _, ok := y[s]; !ok {
			delta = append(delta, s)
		}
	}
	sort.Strings(delta)
	return delta
}

func TestVTAGraphConstruction(t *testing.T) {
	for _, file := range []string{
		"testdata/src/store.go",
		"testdata/src/phi.go",
		"testdata/src/type_conversions.go",
		"testdata/src/type_assertions.go",
		"testdata/src/fields.go",
		"testdata/src/node_uniqueness.go",
		"testdata/src/store_load_alias.go",
		"testdata/src/phi_alias.go",
		"testdata/src/channels.go",
		"testdata/src/generic_channels.go",
		"testdata/src/select.go",
		"testdata/src/stores_arrays.go",
		"testdata/src/maps.go",
		"testdata/src/ranges.go",
		"testdata/src/closures.go",
		"testdata/src/function_alias.go",
		"testdata/src/static_calls.go",
		"testdata/src/dynamic_calls.go",
		"testdata/src/returns.go",
		"testdata/src/panic.go",
	} {
		t.Run(file, func(t *testing.T) {
			prog, want, err := testProg(t, file, ssa.BuilderMode(0))
			if err != nil {
				t.Fatalf("couldn't load test file '%s': %s", file, err)
			}
			if len(want) == 0 {
				t.Fatalf("couldn't find want in `%s`", file)
			}

			fs := ssautil.AllFunctions(prog)

			// First test propagation with lazy-CHA initial call graph.
			g, _ := typePropGraph(fs, makeCalleesFunc(fs, nil))
			got := vtaGraphStr(g)
			if diff := setdiff(want, got); len(diff) > 0 {
				t.Errorf("`%s`: want superset of %v;\n got %v\ndiff: %v", file, want, got, diff)
			}

			// Repeat the test with explicit CHA initial call graph.
			g, _ = typePropGraph(fs, makeCalleesFunc(fs, cha.CallGraph(prog)))
			got = vtaGraphStr(g)
			if diff := setdiff(want, got); len(diff) > 0 {
				t.Errorf("`%s`: want superset of %v;\n got %v\ndiff: %v", file, want, got, diff)
			}
		})
	}
}


================================================
FILE: go/callgraph/vta/helpers_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"bytes"
	"fmt"
	"go/ast"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"

	"golang.org/x/tools/go/ssa"
)

// want extracts the contents of the first comment
// section starting with "WANT:\n". The returned
// content is split into lines without // prefix.
func want(f *ast.File) []string {
	for _, c := range f.Comments {
		text := strings.TrimSpace(c.Text())
		if t, ok := strings.CutPrefix(text, "WANT:\n"); ok {
			return strings.Split(t, "\n")
		}
	}
	return nil
}

// testProg returns an ssa representation of a program at
// `path`, assumed to define package "testdata," and the
// test want result as list of strings.
func testProg(t testing.TB, path string, mode ssa.BuilderMode) (*ssa.Program, []string, error) {
	// Set debug mode to exercise DebugRef instructions.
	pkg, ssapkg := loadFile(t, path, mode|ssa.GlobalDebug)
	return ssapkg.Prog, want(pkg.Syntax[0]), nil
}

// loadFile loads a built SSA package for a single-file package "x.io/testdata".
// (Ideally all uses would be converted over to txtar files with explicit go.mod files.)
//
// TODO(adonovan): factor with similar loadFile in cha/cha_test.go.
func loadFile(t testing.TB, filename string, mode ssa.BuilderMode) (*packages.Package, *ssa.Package) {
	testenv.NeedsGoPackages(t)

	data, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	dir := t.TempDir()
	cfg := &packages.Config{
		Mode: packages.LoadAllSyntax,
		Dir:  dir,
		Overlay: map[string][]byte{
			filepath.Join(dir, "go.mod"): fmt.Appendf(nil, "module x.io\ngo 1.%d", testenv.Go1Point()),

			filepath.Join(dir, "testdata", filepath.Base(filename)): data,
		},
	}
	pkgs, err := packages.Load(cfg, "./testdata")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("got %d packages, want 1", len(pkgs))
	}
	if len(pkgs[0].Syntax) != 1 {
		t.Fatalf("got %d files, want 1", len(pkgs[0].Syntax))
	}
	if num := packages.PrintErrors(pkgs); num > 0 {
		t.Fatalf("packages contained %d errors", num)
	}
	prog, ssapkgs := ssautil.Packages(pkgs, mode)
	prog.Build()
	return pkgs[0], ssapkgs[0]
}

func firstRegInstr(f *ssa.Function) ssa.Value {
	for _, b := range f.Blocks {
		for _, i := range b.Instrs {
			if v, ok := i.(ssa.Value); ok {
				return v
			}
		}
	}
	return nil
}

// funcName returns a name of the function `f`
// prefixed with the name of the receiver type.
func funcName(f *ssa.Function) string {
	recv := f.Signature.Recv()
	if recv == nil {
		return f.Name()
	}
	tp := recv.Type().String()
	return tp[strings.LastIndex(tp, ".")+1:] + "." + f.Name()
}

// callGraphStr stringifes `g` into a list of strings where
// each entry is of the form
//
//	f: cs1 -> f1, f2, ...; ...; csw -> fx, fy, ...
//
// f is a function, cs1, ..., csw are call sites in f, and
// f1, f2, ..., fx, fy, ... are the resolved callees.
func callGraphStr(g *callgraph.Graph) []string {
	var gs []string
	for f, n := range g.Nodes {
		c := make(map[string][]string)
		for _, edge := range n.Out {
			cs := edge.Site.String() // TODO(adonovan): handle Site=nil gracefully
			c[cs] = append(c[cs], funcName(edge.Callee.Func))
		}

		var cs []string
		for site, fs := range c {
			sort.Strings(fs)
			entry := fmt.Sprintf("%v -> %v", site, strings.Join(fs, ", "))
			cs = append(cs, entry)
		}

		sort.Strings(cs)
		entry := fmt.Sprintf("%v: %v", funcName(f), strings.Join(cs, "; "))
		gs = append(gs, removeModulePrefix(entry))
	}
	return gs
}

// Logs the functions of prog to t.
func logFns(t testing.TB, prog *ssa.Program) {
	for fn := range ssautil.AllFunctions(prog) {
		var buf bytes.Buffer
		fn.WriteTo(&buf)
		t.Log(buf.String())
	}
}


================================================
FILE: go/callgraph/vta/initial.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/callgraph/internal/chautil"
	"golang.org/x/tools/go/ssa"
)

// calleesFunc abstracts call graph in one direction,
// from call sites to callees.
type calleesFunc func(ssa.CallInstruction) []*ssa.Function

// makeCalleesFunc returns an initial call graph for vta as a
// calleesFunc. If c is not nil, returns callees as given by c.
// Otherwise, it returns chautil.LazyCallees over fs.
func makeCalleesFunc(fs map[*ssa.Function]bool, c *callgraph.Graph) calleesFunc {
	if c == nil {
		return chautil.LazyCallees(fs)
	}
	return func(call ssa.CallInstruction) []*ssa.Function {
		node := c.Nodes[call.Parent()]
		if node == nil {
			return nil
		}
		var cs []*ssa.Function
		for _, edge := range node.Out {
			if edge.Site == call {
				cs = append(cs, edge.Callee.Func)
			}
		}
		return cs
	}
}


================================================
FILE: go/callgraph/vta/internal/trie/bits.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package trie

import (
	"math/bits"
)

// This file contains bit twiddling functions for Patricia tries.
// Consult this paper for details.
//   C. Okasaki and A. Gill, “Fast mergeable integer maps,” in ACM SIGPLAN
//   Workshop on ML, September 1998, pp. 77–86.

// key is a key in a Map.
type key uint64

// bitpos is the position of a bit. A position is represented by having a 1
// bit in that position.
// Examples:
//   - 0b0010 is the position of the `1` bit in 2.
//     It is the 3rd most specific bit position in big endian encoding
//     (0b0 and 0b1 are more specific).
//   - 0b0100 is the position of the bit that 1 and 5 disagree on.
//   - 0b0 is a special value indicating that all bit agree.
type bitpos uint64

// prefixes represent a set of keys that all agree with the
// prefix up to a bitpos m.
//
// The value for a prefix is determined by the mask(k, m) function.
// (See mask for details on the values.)
// A `p` prefix for position `m` matches a key `k` iff mask(k, m) == p.
// A prefix always mask(p, m) == p.
//
// A key is its own prefix for the bit position 64,
// e.g. seeing a `prefix(key)` is not a problem.
//
// Prefixes should never be turned into keys.
type prefix uint64

// branchingBit returns the position of the first bit in `x` and `y`
// that are not equal.
func branchingBit(x, y prefix) bitpos {
	p := x ^ y
	if p == 0 {
		return 0
	}
	return bitpos(1) << uint(bits.Len64(uint64(p))-1) // uint conversion needed for go1.12
}

// zeroBit returns true if k has a 0 bit at position `b`.
func zeroBit(k prefix, b bitpos) bool {
	return (uint64(k) & uint64(b)) == 0
}

// matchPrefix returns true if a prefix k matches a prefix p up to position `b`.
func matchPrefix(k prefix, p prefix, b bitpos) bool {
	return mask(k, b) == p
}

// mask returns a prefix of `k` with all bits after and including `b` zeroed out.
//
// In big endian encoding, this value is the [64-(m-1)] most significant bits of k
// followed by a `0` bit at bitpos m, followed m-1 `1` bits.
// Examples:
//
//	prefix(0b1011) for a bitpos 0b0100 represents the keys:
//	  0b1000, 0b1001, 0b1010, 0b1011, 0b1100, 0b1101, 0b1110, 0b1111
//
// This mask function has the property that if matchPrefix(k, p, b), then
// k <= p if and only if zeroBit(k, m). This induces binary search tree tries.
// See Okasaki & Gill for more details about this choice of mask function.
//
// mask is idempotent for a given `b`, i.e. mask(mask(p, b), b) == mask(p,b).
func mask(k prefix, b bitpos) prefix {
	return prefix((uint64(k) | (uint64(b) - 1)) & (^uint64(b)))
}

// ord returns true if m comes before n in the bit ordering.
func ord(m, n bitpos) bool {
	return m > n // big endian encoding
}

// prefixesOverlap returns true if there is some key a prefix `p` for bitpos `m`
// can hold that can also be held by a prefix `q` for some bitpos `n`.
//
// This is equivalent to:
//
//	m ==n && p == q,
//	higher(m, n) && matchPrefix(q, p, m), or
//	higher(n, m) && matchPrefix(p, q, n)
func prefixesOverlap(p prefix, m bitpos, q prefix, n bitpos) bool {
	fbb := n
	if ord(m, n) {
		fbb = m
	}
	return mask(p, fbb) == mask(q, fbb)
	// Lemma:
	//   mask(p, fbb) == mask(q, fbb)
	// iff
	//   m > n && matchPrefix(q, p, m) or  (note: big endian encoding)
	//   m < n && matchPrefix(p, q, n) or  (note: big endian encoding)
	//   m ==n && p == q
	// Quick-n-dirty proof:
	// p == mask(p0, m) for some p0 by precondition.
	// q == mask(q0, n) for some q0 by precondition.
	// So mask(p, m) == p and mask(q, n) == q as mask(*, n') is idempotent.
	//
	// [=> proof]
	// Suppose mask(p, fbb) == mask(q, fbb).
	// if m ==n, p == mask(p, m) == mask(p, fbb) == mask(q, fbb) == mask(q, n) == q
	// if m > n, fbb = firstBranchBit(m, n) = m (big endian).
	//   p == mask(p, m) == mask(p, fbb) == mask(q, fbb) == mask(q, m)
	//   so mask(q, m) == p or matchPrefix(q, p, m)
	// if m < n, is symmetric to the above.
	//
	// [<= proof]
	// case m ==n && p == q. Then mask(p, fbb) == mask(q, fbb)
	//
	// case m > n && matchPrefix(q, p, m).
	// fbb == firstBranchBit(m, n) == m (by m>n).
	// mask(q, fbb) == mask(q, m) == p == mask(p, m) == mask(p, fbb)
	//
	// case m < n && matchPrefix(p, q, n) is symmetric.
}


================================================
FILE: go/callgraph/vta/internal/trie/bits_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.13

package trie

import (
	"math/rand"
	"testing"
)

func TestMask(t *testing.T) {
	for _, c := range []struct {
		p    prefix
		b    bitpos
		want prefix
	}{
		{
			p:    0b00001000,
			b:    0b00000100,
			want: 0b00001011,
		}, {
			p:    0b01011011,
			b:    0b00000000,
			want: ^prefix(0),
		}, {
			p:    0b01011011,
			b:    0b00000001,
			want: 0b01011010,
		}, {
			p:    0b01011011,
			b:    0b00000010,
			want: 0b01011001,
		}, {
			p:    0b01011011,
			b:    0b00000100,
			want: 0b01011011,
		}, {
			p:    0b01011011,
			b:    0b00001000,
			want: 0b01010111,
		}, {
			p:    0b01011011,
			b:    0b00010000,
			want: 0b01001111,
		}, {
			p:    0b01011011,
			b:    0b00100000,
			want: 0b01011111,
		}, {
			p:    0b01011011,
			b:    0b01000000,
			want: 0b00111111,
		}, {
			p:    0b01011011,
			b:    0b01000000,
			want: 0b00111111,
		}, {
			p:    0b01011011,
			b:    0b10000000,
			want: 0b01111111,
		},
	} {
		if got := mask(c.p, c.b); got != c.want {
			t.Errorf("mask(%#b,%#b) got %#b. want %#b", c.p, c.b, got, c.want)
		}
	}
}

func TestMaskImpotent(t *testing.T) {
	// test mask(mask(p, b), b) == mask(p,b)
	for _, p := range []prefix{
		0b0, 0b1, 0b100, ^prefix(0b0), ^prefix(0b10),
	} {
		for _, b := range []bitpos{
			0, 0b1, 1 << 2, 1 << 63,
		} {
			once := mask(p, b)
			twice := mask(once, b)
			if once != twice {
				t.Errorf("mask(mask(%#b,%#b), %#b) != mask(%#b,%#b) got %#b. want %#b",
					p, b, b, p, b, twice, once)
			}
		}
	}
}

func TestMatchPrefix(t *testing.T) {
	for _, c := range []struct {
		k prefix
		p prefix
		b bitpos
	}{
		{
			k: 0b1000,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1001,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1010,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1011,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1100,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1101,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1110,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b1111,
			p: 0b1011,
			b: 0b0100,
		},
	} {
		if !matchPrefix(c.k, c.p, c.b) {
			t.Errorf("matchPrefix(%#b, %#b,%#b) should be true", c.k, c.p, c.b)
		}
	}
}

func TestNotMatchPrefix(t *testing.T) {
	for _, c := range []struct {
		k prefix
		p prefix
		b bitpos
	}{
		{
			k: 0b0000,
			p: 0b1011,
			b: 0b0100,
		}, {
			k: 0b0010,
			p: 0b1011,
			b: 0b0100,
		},
	} {
		if matchPrefix(c.k, c.p, c.b) {
			t.Errorf("matchPrefix(%#b, %#b,%#b) should be false", c.k, c.p, c.b)
		}
	}
}

func TestBranchingBit(t *testing.T) {
	for _, c := range []struct {
		x    prefix
		y    prefix
		want bitpos
	}{
		{
			x:    0b0000,
			y:    0b1011,
			want: 0b1000,
		}, {
			x:    0b1010,
			y:    0b1011,
			want: 0b0001,
		}, {
			x:    0b1011,
			y:    0b1111,
			want: 0b0100,
		}, {
			x:    0b1011,
			y:    0b1001,
			want: 0b0010,
		},
	} {
		if got := branchingBit(c.x, c.y); got != c.want {
			t.Errorf("branchingBit(%#b, %#b,) is not expected value. got %#b want %#b",
				c.x, c.y, got, c.want)
		}
	}
}

func TestZeroBit(t *testing.T) {
	for _, c := range []struct {
		k prefix
		b bitpos
	}{
		{
			k: 0b1000,
			b: 0b0100,
		}, {
			k: 0b1001,
			b: 0b0100,
		}, {
			k: 0b1010,
			b: 0b0100,
		},
	} {
		if !zeroBit(c.k, c.b) {
			t.Errorf("zeroBit(%#b, %#b) should be true", c.k, c.b)
		}
	}
}
func TestZeroBitFails(t *testing.T) {
	for _, c := range []struct {
		k prefix
		b bitpos
	}{
		{
			k: 0b1000,
			b: 0b1000,
		}, {
			k: 0b1001,
			b: 0b0001,
		}, {
			k: 0b1010,
			b: 0b0010,
		}, {
			k: 0b1011,
			b: 0b0001,
		},
	} {
		if zeroBit(c.k, c.b) {
			t.Errorf("zeroBit(%#b, %#b) should be false", c.k, c.b)
		}
	}
}

func TestOrd(t *testing.T) {
	a := bitpos(0b0010)
	b := bitpos(0b1000)
	if ord(a, b) {
		t.Errorf("ord(%#b, %#b) should be false", a, b)
	}
	if !ord(b, a) {
		t.Errorf("ord(%#b, %#b) should be true", b, a)
	}
	if ord(a, a) {
		t.Errorf("ord(%#b, %#b) should be false", a, a)
	}
	if !ord(a, 0) {
		t.Errorf("ord(%#b, %#b) should be true", a, 0)
	}
}

func TestPrefixesOverlapLemma(t *testing.T) {
	// test
	//   mask(p, fbb) == mask(q, fbb)
	// iff
	//   m > n && matchPrefix(q, p, m) or  (note: big endian encoding)
	//   m < n && matchPrefix(p, q, n) or  (note: big endian encoding)
	//   m ==n && p == q

	// Case 1: mask(p, fbb) == mask(q, fbb) => m > n && matchPrefix(q, p, m)
	m, n := bitpos(1<<2), bitpos(1<<1)
	p, q := mask(0b100, m), mask(0b010, n)
	if !(prefixesOverlap(p, m, q, n) && m > n && matchPrefix(q, p, m)) {
		t.Errorf("prefixesOverlap(%#b, %#b, %#b, %#b) lemma does not hold",
			p, m, q, n)
	}
	// Case 2: mask(p, fbb) == mask(q, fbb) => m < n && matchPrefix(p, q, n)
	m, n = bitpos(1<<2), bitpos(1<<3)
	p, q = mask(0b100, m), mask(0b1000, n)
	if !(prefixesOverlap(p, m, q, n) && m < n && matchPrefix(p, q, n)) {
		t.Errorf("prefixesOverlap(%#b, %#b, %#b, %#b) lemma does not hold",
			p, m, q, n)
	}
	// Case 3: mask(p, fbb) == mask(q, fbb) => m < n && matchPrefix(p, q, n)
	m, n = bitpos(1<<2), bitpos(1<<2)
	p, q = mask(0b100, m), mask(0b001, n)
	if !(prefixesOverlap(p, m, q, n) && m == n && p == q) {
		t.Errorf("prefixesOverlap(%#b, %#b, %#b, %#b) lemma does not hold",
			p, m, q, n)
	}
	// Case 4: mask(p, fbb) != mask(q, fbb)
	m, n = bitpos(1<<1), bitpos(1<<1)
	p, q = mask(0b100, m), mask(0b001, n)
	if prefixesOverlap(p, m, q, n) ||
		(m > n && matchPrefix(q, p, m)) ||
		(m < n && matchPrefix(p, q, n)) ||
		(m == n && p == q) {
		t.Errorf("prefixesOverlap(%#b, %#b, %#b, %#b) lemma does not hold",
			p, m, q, n)
	}

	// Do a few more random cases
	r := rand.New(rand.NewSource(123))
	N := 2000
	for i := 0; i < N; i++ {
		m := bitpos(1 << (r.Uint64() % (64 + 1)))
		n := bitpos(1 << (r.Uint64() % (64 + 1)))

		p := mask(prefix(r.Uint64()), m)
		q := mask(prefix(r.Uint64()), n)

		lhs := prefixesOverlap(p, m, q, n)
		rhs := (m > n && matchPrefix(q, p, m)) ||
			(m < n && matchPrefix(p, q, n)) ||
			(m == n && p == q)

		if lhs != rhs {
			t.Errorf("prefixesOverlap(%#b, %#b, %#b, %#b) != <lemma> got %v. want %v",
				p, m, q, n, lhs, rhs)
		}
	}
}


================================================
FILE: go/callgraph/vta/internal/trie/builder.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package trie

// Collision functions combine a left and right hand side (lhs and rhs) values
// the two values are associated with the same key and produces the value that
// will be stored for the key.
//
// Collision functions must be idempotent:
//
//	collision(x, x) == x for all x.
//
// Collisions functions may be applied whenever a value is inserted
// or two maps are merged, or intersected.
type Collision func(lhs any, rhs any) any

// TakeLhs always returns the left value in a collision.
func TakeLhs(lhs, rhs any) any { return lhs }

// TakeRhs always returns the right hand side in a collision.
func TakeRhs(lhs, rhs any) any { return rhs }

// Builder creates new Map. Each Builder has a unique Scope.
//
// IMPORTANT:  Nodes are hash-consed internally to reduce memory consumption. To
// support hash-consing Builders keep an internal Map of all of the Maps that they
// have created. To GC any of the Maps created by the Builder, all references to
// the Builder must be dropped. This includes MutMaps.
type Builder struct {
	scope Scope

	// hash-consing maps for each node type.
	empty    *empty
	leaves   map[leaf]*leaf
	branches map[branch]*branch
	// It may be possible to support more types of patricia tries
	// (e.g. non-hash-consed) by making Builder an interface and abstracting
	// the mkLeaf and mkBranch functions.
}

// NewBuilder creates a new Builder with a unique Scope.
func NewBuilder() *Builder {
	s := newScope()
	return &Builder{
		scope:    s,
		empty:    &empty{s},
		leaves:   make(map[leaf]*leaf),
		branches: make(map[branch]*branch),
	}
}

func (b *Builder) Scope() Scope { return b.scope }

// Rescope changes the builder's scope to a new unique Scope.
//
// Any Maps created using the previous scope need to be Cloned
// before any operation.
//
// This makes the old internals of the Builder eligible to be GC'ed.
func (b *Builder) Rescope() {
	s := newScope()
	b.scope = s
	b.empty = &empty{s}
	b.leaves = make(map[leaf]*leaf)
	b.branches = make(map[branch]*branch)
}

// Empty is the empty map.
func (b *Builder) Empty() Map { return Map{b.Scope(), b.empty} }

// InsertWith inserts a new association from k to v into the Map m to create a new map
// in the current scope and handle collisions using the collision function c.
//
// This is roughly corresponds to updating a map[uint64]interface{} by:
//
//	if _, ok := m[k]; ok { m[k] = c(m[k], v} else { m[k] = v}
//
// An insertion or update happened whenever Insert(m, ...) != m .
func (b *Builder) InsertWith(c Collision, m Map, k uint64, v any) Map {
	m = b.Clone(m)
	return Map{b.Scope(), b.insert(c, m.n, b.mkLeaf(key(k), v), false)}
}

// Inserts a new association from key to value into the Map m to create
// a new map in the current scope.
//
// If there was a previous value mapped by key, keep the previously mapped value.
// This is roughly corresponds to updating a map[uint64]interface{} by:
//
//	if _, ok := m[k]; ok { m[k] = val }
//
// This is equivalent to b.Merge(m, b.Create({k: v})).
func (b *Builder) Insert(m Map, k uint64, v any) Map {
	return b.InsertWith(TakeLhs, m, k, v)
}

// Updates a (key, value) in the map. This is roughly corresponds to
// updating a map[uint64]interface{} by:
//
//	m[key] = val
func (b *Builder) Update(m Map, key uint64, val any) Map {
	return b.InsertWith(TakeRhs, m, key, val)
}

// Merge two maps lhs and rhs to create a new map in the current scope.
//
// Whenever there is a key in both maps (a collision), the resulting value mapped by
// the key will be `c(lhs[key], rhs[key])`.
func (b *Builder) MergeWith(c Collision, lhs, rhs Map) Map {
	lhs, rhs = b.Clone(lhs), b.Clone(rhs)
	return Map{b.Scope(), b.merge(c, lhs.n, rhs.n)}
}

// Merge two maps lhs and rhs to create a new map in the current scope.
//
// Whenever there is a key in both maps (a collision), the resulting value mapped by
// the key will be the value in lhs `b.Collision(lhs[key], rhs[key])`.
func (b *Builder) Merge(lhs, rhs Map) Map {
	return b.MergeWith(TakeLhs, lhs, rhs)
}

// Clone returns a Map that contains the same (key, value) elements
// within b.Scope(), i.e. return m if m.Scope() == b.Scope() or return
// a deep copy of m within b.Scope() otherwise.
func (b *Builder) Clone(m Map) Map {
	if m.Scope() == b.Scope() {
		return m
	} else if m.n == nil {
		return Map{b.Scope(), b.empty}
	}
	return Map{b.Scope(), b.clone(m.n)}
}
func (b *Builder) clone(n node) node {
	switch n := n.(type) {
	case *empty:
		return b.empty
	case *leaf:
		return b.mkLeaf(n.k, n.v)
	case *branch:
		return b.mkBranch(n.prefix, n.branching, b.clone(n.left), b.clone(n.right))
	default:
		panic("unreachable")
	}
}

// Remove a key from a Map m and return the resulting Map.
func (b *Builder) Remove(m Map, k uint64) Map {
	m = b.Clone(m)
	return Map{b.Scope(), b.remove(m.n, key(k))}
}

// Intersect Maps lhs and rhs and returns a map with all of the keys in
// both lhs and rhs and the value comes from lhs, i.e.
//
//	{(k, lhs[k]) | k in lhs, k in rhs}.
func (b *Builder) Intersect(lhs, rhs Map) Map {
	return b.IntersectWith(TakeLhs, lhs, rhs)
}

// IntersectWith take lhs and rhs and returns the intersection
// with the value coming from the collision function, i.e.
//
//	{(k, c(lhs[k], rhs[k]) ) | k in lhs, k in rhs}.
//
// The elements of the resulting map are always { <k, c(lhs[k], rhs[k]) > }
// for each key k that a key in both lhs and rhs.
func (b *Builder) IntersectWith(c Collision, lhs, rhs Map) Map {
	l, r := b.Clone(lhs), b.Clone(rhs)
	return Map{b.Scope(), b.intersect(c, l.n, r.n)}
}

// MutMap is a convenient wrapper for a Map and a *Builder that will be used to create
// new Maps from it.
type MutMap struct {
	B *Builder
	M Map
}

// MutEmpty is an empty MutMap for a builder.
func (b *Builder) MutEmpty() MutMap {
	return MutMap{b, b.Empty()}
}

// Insert an element into the map using the collision function for the builder.
// Returns true if the element was inserted.
func (mm *MutMap) Insert(k uint64, v any) bool {
	old := mm.M
	mm.M = mm.B.Insert(old, k, v)
	return old != mm.M
}

// Updates an element in the map. Returns true if the map was updated.
func (mm *MutMap) Update(k uint64, v any) bool {
	old := mm.M
	mm.M = mm.B.Update(old, k, v)
	return old != mm.M
}

// Removes a key from the map. Returns true if the element was removed.
func (mm *MutMap) Remove(k uint64) bool {
	old := mm.M
	mm.M = mm.B.Remove(old, k)
	return old != mm.M
}

// Merge another map into the current one using the collision function
// for the builder. Returns true if the map changed.
func (mm *MutMap) Merge(other Map) bool {
	old := mm.M
	mm.M = mm.B.Merge(old, other)
	return old != mm.M
}

// Intersect another map into the current one using the collision function
// for the builder. Returns true if the map changed.
func (mm *MutMap) Intersect(other Map) bool {
	old := mm.M
	mm.M = mm.B.Intersect(old, other)
	return old != mm.M
}

func (b *Builder) Create(m map[uint64]any) Map {
	var leaves []*leaf
	for k, v := range m {
		leaves = append(leaves, b.mkLeaf(key(k), v))
	}
	return Map{b.Scope(), b.create(leaves)}
}

// Merge another map into the current one using the collision function
// for the builder. Returns true if the map changed.
func (mm *MutMap) MergeWith(c Collision, other Map) bool {
	old := mm.M
	mm.M = mm.B.MergeWith(c, old, other)
	return old != mm.M
}

// creates a map for a collection of leaf nodes.
func (b *Builder) create(leaves []*leaf) node {
	n := len(leaves)
	if n == 0 {
		return b.empty
	} else if n == 1 {
		return leaves[0]
	}
	// Note: we can do a more sophisticated algorithm by:
	// - sorting the leaves ahead of time,
	// - taking the prefix and branching bit of the min and max key,
	// - binary searching for the branching bit,
	// - splitting exactly where the branch will be, and
	// - making the branch node for this prefix + branching bit.
	// Skipping until this is a performance bottleneck.

	m := n / 2 // (n >= 2) ==> 1 <= m < n
	l, r := leaves[:m], leaves[m:]
	return b.merge(nil, b.create(l), b.create(r))
}

// mkLeaf returns the hash-consed representative of (k, v) in the current scope.
func (b *Builder) mkLeaf(k key, v any) *leaf {
	rep, ok := b.leaves[leaf{k, v}]
	if !ok {
		rep = &leaf{k, v} // heap-allocated copy
		b.leaves[leaf{k, v}] = rep
	}
	return rep
}

// mkBranch returns the hash-consed representative of the tuple
//
//	(prefix, branch, left, right)
//
// in the current scope.
func (b *Builder) mkBranch(p prefix, bp bitpos, left node, right node) *branch {
	br := branch{
		sz:        left.size() + right.size(),
		prefix:    p,
		branching: bp,
		left:      left,
		right:     right,
	}
	rep, ok := b.branches[br]
	if !ok {
		rep = new(branch) // heap-allocated copy
		*rep = br
		b.branches[br] = rep
	}
	return rep
}

// join two maps with prefixes p0 and p1 that are *known* to disagree.
func (b *Builder) join(p0 prefix, t0 node, p1 prefix, t1 node) *branch {
	m := branchingBit(p0, p1)
	var left, right node
	if zeroBit(p0, m) {
		left, right = t0, t1
	} else {
		left, right = t1, t0
	}
	prefix := mask(p0, m)
	return b.mkBranch(prefix, m, left, right)
}

// collide two leaves with the same key to create a leaf
// with the collided value.
func (b *Builder) collide(c Collision, left, right *leaf) *leaf {
	if left == right {
		return left // c is idempotent: c(x, x) == x
	}
	val := left.v // keep the left value by default if c is nil
	if c != nil {
		val = c(left.v, right.v)
	}
	switch val {
	case left.v:
		return left
	case right.v:
		return right
	default:
		return b.mkLeaf(left.k, val)
	}
}

// inserts a leaf l into a map m and returns the resulting map.
// When lhs is true, l is the left hand side in a collision.
// Both l and m are in the current scope.
func (b *Builder) insert(c Collision, m node, l *leaf, lhs bool) node {
	switch m := m.(type) {
	case *empty:
		return l
	case *leaf:
		if m.k == l.k {
			left, right := l, m
			if !lhs {
				left, right = right, left
			}
			return b.collide(c, left, right)
		}
		return b.join(prefix(l.k), l, prefix(m.k), m)
	case *branch:
		// fallthrough
	}
	// m is a branch
	br := m.(*branch)
	if !matchPrefix(prefix(l.k), br.prefix, br.branching) {
		return b.join(prefix(l.k), l, br.prefix, br)
	}
	var left, right node
	if zeroBit(prefix(l.k), br.branching) {
		left, right = b.insert(c, br.left, l, lhs), br.right
	} else {
		left, right = br.left, b.insert(c, br.right, l, lhs)
	}
	if left == br.left && right == br.right {
		return m
	}
	return b.mkBranch(br.prefix, br.branching, left, right)
}

// merge two maps in the current scope.
func (b *Builder) merge(c Collision, lhs, rhs node) node {
	if lhs == rhs {
		return lhs
	}
	switch lhs := lhs.(type) {
	case *empty:
		return rhs
	case *leaf:
		return b.insert(c, rhs, lhs, true)
	case *branch:
		switch rhs := rhs.(type) {
		case *empty:
			return lhs
		case *leaf:
			return b.insert(c, lhs, rhs, false)
		case *branch:
			// fallthrough
		}
	}

	// Last remaining case is branch merging.
	// For brevity, we adopt the Okasaki and Gill naming conventions
	// for branching and prefixes.
	s, t := lhs.(*branch), rhs.(*branch)
	p, m := s.prefix, s.branching
	q, n := t.prefix, t.branching

	if m == n && p == q { // prefixes are identical.
		left, right := b.merge(c, s.left, t.left), b.merge(c, s.right, t.right)
		return b.mkBranch(p, m, left, right)
	}
	if !prefixesOverlap(p, m, q, n) {
		return b.join(p, s, q, t) // prefixes are disjoint.
	}
	// prefixesOverlap(p, m, q, n) && !(m ==n && p == q)
	// By prefixesOverlap(...), either:
	//   higher(m, n) && matchPrefix(q, p, m), or
	//   higher(n, m) && matchPrefix(p, q, n)
	// So either s or t may can be merged with one branch or the other.
	switch {
	case ord(m, n) && zeroBit(q, m):
		return b.mkBranch(p, m, b.merge(c, s.left, t), s.right)
	case ord(m, n) && !zeroBit(q, m):
		return b.mkBranch(p, m, s.left, b.merge(c, s.right, t))
	case ord(n, m) && zeroBit(p, n):
		return b.mkBranch(q, n, b.merge(c, s, t.left), t.right)
	default:
		return b.mkBranch(q, n, t.left, b.merge(c, s, t.right))
	}
}

func (b *Builder) remove(m node, k key) node {
	switch m := m.(type) {
	case *empty:
		return m
	case *leaf:
		if m.k == k {
			return b.empty
		}
		return m
	case *branch:
		// fallthrough
	}
	br := m.(*branch)
	kp := prefix(k)
	if !matchPrefix(kp, br.prefix, br.branching) {
		// The prefix does not match. kp is not in br.
		return br
	}
	// the prefix matches. try to remove from the left or right branch.
	left, right := br.left, br.right
	if zeroBit(kp, br.branching) {
		left = b.remove(left, k) // k may be in the left branch.
	} else {
		right = b.remove(right, k) // k may be in the right branch.
	}
	if left == br.left && right == br.right {
		return br // no update
	} else if _, ok := left.(*empty); ok {
		return right // left updated and is empty.
	} else if _, ok := right.(*empty); ok {
		return left // right updated and is empty.
	}
	// Either left or right updated. Both left and right are not empty.
	// The left and right branches still share the same prefix and disagree
	// on the same branching bit. It is safe to directly create the branch.
	return b.mkBranch(br.prefix, br.branching, left, right)
}

func (b *Builder) intersect(c Collision, l, r node) node {
	if l == r {
		return l
	}
	switch l := l.(type) {
	case *empty:
		return b.empty
	case *leaf:
		if rleaf := r.find(l.k); rleaf != nil {
			return b.collide(c, l, rleaf)
		}
		return b.empty
	case *branch:
		switch r := r.(type) {
		case *empty:
			return b.empty
		case *leaf:
			if lleaf := l.find(r.k); lleaf != nil {
				return b.collide(c, lleaf, r)
			}
			return b.empty
		case *branch:
			// fallthrough
		}
	}
	// Last remaining case is branch intersection.
	s, t := l.(*branch), r.(*branch)
	p, m := s.prefix, s.branching
	q, n := t.prefix, t.branching

	if m == n && p == q {
		// prefixes are identical.
		left, right := b.intersect(c, s.left, t.left), b.intersect(c, s.right, t.right)
		if _, ok := left.(*empty); ok {
			return right
		} else if _, ok := right.(*empty); ok {
			return left
		}
		// The left and right branches are both non-empty.
		// They still share the same prefix and disagree on the same branching bit.
		// It is safe to directly create the branch.
		return b.mkBranch(p, m, left, right)
	}

	if !prefixesOverlap(p, m, q, n) {
		return b.empty // The prefixes share no keys.
	}
	// prefixesOverlap(p, m, q, n) && !(m ==n && p == q)
	// By prefixesOverlap(...), either:
	//   ord(m, n) && matchPrefix(q, p, m), or
	//   ord(n, m) && matchPrefix(p, q, n)
	// So either s or t may be a strict subtree of the other.
	var lhs, rhs node
	switch {
	case ord(m, n) && zeroBit(q, m):
		lhs, rhs = s.left, t
	case ord(m, n) && !zeroBit(q, m):
		lhs, rhs = s.right, t
	case ord(n, m) && zeroBit(p, n):
		lhs, rhs = s, t.left
	default:
		lhs, rhs = s, t.right
	}
	return b.intersect(c, lhs, rhs)
}


================================================
FILE: go/callgraph/vta/internal/trie/op_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package trie_test

import (
	"fmt"
	"math/rand"
	"reflect"
	"testing"
	"time"

	"golang.org/x/tools/go/callgraph/vta/internal/trie"
	"maps"
)

// This file tests trie.Map by cross checking operations on a collection of
// trie.Map's against a collection of map[uint64]interface{}. This includes
// both limited fuzz testing for correctness and benchmarking.

// mapCollection is effectively a []map[uint64]interface{}.
// These support operations being applied to the i'th maps.
type mapCollection interface {
	Elements() []map[uint64]any

	DeepEqual(l, r int) bool
	Lookup(id int, k uint64) (any, bool)

	Insert(id int, k uint64, v any)
	Update(id int, k uint64, v any)
	Remove(id int, k uint64)
	Intersect(l int, r int)
	Merge(l int, r int)
	Clear(id int)

	Average(l int, r int)
	Assign(l int, r int)
}

// opCode of an operation.
type opCode int

const (
	deepEqualsOp opCode = iota
	lookupOp
	insert
	update
	remove
	merge
	intersect
	clear
	takeAverage
	assign
)

func (op opCode) String() string {
	switch op {
	case deepEqualsOp:
		return "DE"
	case lookupOp:
		return "LO"
	case insert:
		return "IN"
	case update:
		return "UP"
	case remove:
		return "RE"
	case merge:
		return "ME"
	case intersect:
		return "IT"
	case clear:
		return "CL"
	case takeAverage:
		return "AV"
	case assign:
		return "AS"
	default:
		return "??"
	}
}

// A mapCollection backed by MutMaps.
type trieCollection struct {
	b     *trie.Builder
	tries []trie.MutMap
}

func (c *trieCollection) Elements() []map[uint64]any {
	var maps []map[uint64]any
	for _, m := range c.tries {
		maps = append(maps, trie.Elems(m.M))
	}
	return maps
}
func (c *trieCollection) Eq(id int, m map[uint64]any) bool {
	elems := trie.Elems(c.tries[id].M)
	return !reflect.DeepEqual(elems, m)
}

func (c *trieCollection) Lookup(id int, k uint64) (any, bool) {
	return c.tries[id].M.Lookup(k)
}
func (c *trieCollection) DeepEqual(l, r int) bool {
	return c.tries[l].M.DeepEqual(c.tries[r].M)
}

func (c *trieCollection) Add() {
	c.tries = append(c.tries, c.b.MutEmpty())
}

func (c *trieCollection) Insert(id int, k uint64, v any) {
	c.tries[id].Insert(k, v)
}

func (c *trieCollection) Update(id int, k uint64, v any) {
	c.tries[id].Update(k, v)
}

func (c *trieCollection) Remove(id int, k uint64) {
	c.tries[id].Remove(k)
}

func (c *trieCollection) Intersect(l int, r int) {
	c.tries[l].Intersect(c.tries[r].M)
}

func (c *trieCollection) Merge(l int, r int) {
	c.tries[l].Merge(c.tries[r].M)
}

func (c *trieCollection) Average(l int, r int) {
	c.tries[l].MergeWith(average, c.tries[r].M)
}

func (c *trieCollection) Clear(id int) {
	c.tries[id] = c.b.MutEmpty()
}
func (c *trieCollection) Assign(l, r int) {
	c.tries[l] = c.tries[r]
}

func average(x any, y any) any {
	if x, ok := x.(float32); ok {
		if y, ok := y.(float32); ok {
			return (x + y) / 2.0
		}
	}
	return x
}

type builtinCollection []map[uint64]any

func (c builtinCollection) Elements() []map[uint64]any {
	return c
}

func (c builtinCollection) Lookup(id int, k uint64) (any, bool) {
	v, ok := c[id][k]
	return v, ok
}
func (c builtinCollection) DeepEqual(l, r int) bool {
	return reflect.DeepEqual(c[l], c[r])
}

func (c builtinCollection) Insert(id int, k uint64, v any) {
	if _, ok := c[id][k]; !ok {
		c[id][k] = v
	}
}

func (c builtinCollection) Update(id int, k uint64, v any) {
	c[id][k] = v
}

func (c builtinCollection) Remove(id int, k uint64) {
	delete(c[id], k)
}

func (c builtinCollection) Intersect(l int, r int) {
	result := map[uint64]any{}
	for k, v := range c[l] {
		if _, ok := c[r][k]; ok {
			result[k] = v
		}
	}
	c[l] = result
}

func (c builtinCollection) Merge(l int, r int) {
	result := map[uint64]any{}
	maps.Copy(result, c[r])
	maps.Copy(result, c[l])
	c[l] = result
}

func (c builtinCollection) Average(l int, r int) {
	avg := map[uint64]any{}
	for k, lv := range c[l] {
		if rv, ok := c[r][k]; ok {
			avg[k] = average(lv, rv)
		} else {
			avg[k] = lv // add elements just in l
		}
	}
	for k, rv := range c[r] {
		if _, ok := c[l][k]; !ok {
			avg[k] = rv // add elements just in r
		}
	}
	c[l] = avg
}

func (c builtinCollection) Assign(l, r int) {
	m := map[uint64]any{}
	maps.Copy(m, c[r])
	c[l] = m
}

func (c builtinCollection) Clear(id int) {
	c[id] = map[uint64]any{}
}

func newTriesCollection(size int) *trieCollection {
	tc := &trieCollection{
		b:     trie.NewBuilder(),
		tries: make([]trie.MutMap, size),
	}
	for i := range size {
		tc.tries[i] = tc.b.MutEmpty()
	}
	return tc
}

func newMapsCollection(size int) *builtinCollection {
	maps := make(builtinCollection, size)
	for i := range size {
		maps[i] = map[uint64]any{}
	}
	return &maps
}

// operation on a map collection.
type operation struct {
	code opCode
	l, r int
	k    uint64
	v    float32
}

// Apply the operation to maps.
func (op operation) Apply(maps mapCollection) any {
	type lookupresult struct {
		v  any
		ok bool
	}
	switch op.code {
	case deepEqualsOp:
		return maps.DeepEqual(op.l, op.r)
	case lookupOp:
		v, ok := maps.Lookup(op.l, op.k)
		return lookupresult{v, ok}
	case insert:
		maps.Insert(op.l, op.k, op.v)
	case update:
		maps.Update(op.l, op.k, op.v)
	case remove:
		maps.Remove(op.l, op.k)
	case merge:
		maps.Merge(op.l, op.r)
	case intersect:
		maps.Intersect(op.l, op.r)
	case clear:
		maps.Clear(op.l)
	case takeAverage:
		maps.Average(op.l, op.r)
	case assign:
		maps.Assign(op.l, op.r)
	}
	return nil
}

// Returns a collection of op codes with dist[op] copies of op.
func distribution(dist map[opCode]int) []opCode {
	var codes []opCode
	for op, n := range dist {
		for range n {
			codes = append(codes, op)
		}
	}
	return codes
}

// options for generating a random operation.
type options struct {
	maps   int
	maxKey uint64
	maxVal int
	codes  []opCode
}

// returns a random operation using r as a source of randomness.
func randOperator(r *rand.Rand, opts options) operation {
	id := func() int { return r.Intn(opts.maps) }
	key := func() uint64 { return r.Uint64() % opts.maxKey }
	val := func() float32 { return float32(r.Intn(opts.maxVal)) }
	switch code := opts.codes[r.Intn(len(opts.codes))]; code {
	case lookupOp, remove:
		return operation{code: code, l: id(), k: key()}
	case insert, update:
		return operation{code: code, l: id(), k: key(), v: val()}
	case deepEqualsOp, merge, intersect, takeAverage, assign:
		return operation{code: code, l: id(), r: id()}
	case clear:
		return operation{code: code, l: id()}
	default:
		panic("Invalid op code")
	}
}

func randOperators(r *rand.Rand, numops int, opts options) []operation {
	ops := make([]operation, numops)
	for i := range numops {
		ops[i] = randOperator(r, opts)
	}
	return ops
}

// TestOperations applies a series of random operations to collection of
// trie.MutMaps and map[uint64]interface{}. It tests for the maps being equal.
func TestOperations(t *testing.T) {
	seed := time.Now().UnixNano()
	s := rand.NewSource(seed)
	r := rand.New(s)
	t.Log("seed: ", seed)

	size := 10
	N := 100000
	ops := randOperators(r, N, options{
		maps:   size,
		maxKey: 128,
		maxVal: 100,
		codes: distribution(map[opCode]int{
			deepEqualsOp: 1,
			lookupOp:     10,
			insert:       10,
			update:       10,
			remove:       10,
			merge:        10,
			intersect:    10,
			clear:        2,
			takeAverage:  5,
			assign:       5,
		}),
	})

	var tries mapCollection = newTriesCollection(size)
	var maps mapCollection = newMapsCollection(size)
	check := func() error {
		if got, want := tries.Elements(), maps.Elements(); !reflect.DeepEqual(got, want) {
			return fmt.Errorf("elements of tries and maps and tries differed. got %v want %v", got, want)
		}
		return nil
	}

	for i, op := range ops {
		got, want := op.Apply(tries), op.Apply(maps)
		if got != want {
			t.Errorf("op[%d]: (%v).Apply(%v) != (%v).Apply(%v). got %v want %v",
				i, op, tries, op, maps, got, want)
		}
	}
	if err := check(); err != nil {
		t.Errorf("%d operators failed with %s", size, err)
		t.Log("Rerunning with more checking")
		tries, maps = newTriesCollection(size), newMapsCollection(size)
		for i, op := range ops {
			op.Apply(tries)
			op.Apply(maps)
			if err := check(); err != nil {
				t.Fatalf("Failed first on op[%d]=%v: %v", i, op, err)
			}
		}
	}
}

func run(b *testing.B, opts options, seed int64, mk func(int) mapCollection) {
	r := rand.New(rand.NewSource(seed))
	ops := randOperators(r, b.N, opts)
	maps := mk(opts.maps)
	for _, op := range ops {
		op.Apply(maps)
	}
}

var standard options = options{
	maps:   10,
	maxKey: 128,
	maxVal: 100,
	codes: distribution(map[opCode]int{
		deepEqualsOp: 1,
		lookupOp:     20,
		insert:       20,
		update:       20,
		remove:       20,
		merge:        10,
		intersect:    10,
		clear:        1,
		takeAverage:  5,
		assign:       20,
	}),
}

func BenchmarkTrieStandard(b *testing.B) {
	run(b, standard, 123, func(size int) mapCollection {
		return newTriesCollection(size)
	})
}

func BenchmarkMapsStandard(b *testing.B) {
	run(b, standard, 123, func(size int) mapCollection {
		return newMapsCollection(size)
	})
}

var smallWide options = options{
	maps:   100,
	maxKey: 100,
	maxVal: 8,
	codes: distribution(map[opCode]int{
		deepEqualsOp: 0,
		lookupOp:     0,
		insert:       30,
		update:       20,
		remove:       0,
		merge:        10,
		intersect:    0,
		clear:        1,
		takeAverage:  0,
		assign:       30,
	}),
}

func BenchmarkTrieSmallWide(b *testing.B) {
	run(b, smallWide, 456, func(size int) mapCollection {
		return newTriesCollection(size)
	})
}

func BenchmarkMapsSmallWide(b *testing.B) {
	run(b, smallWide, 456, func(size int) mapCollection {
		return newMapsCollection(size)
	})
}


================================================
FILE: go/callgraph/vta/internal/trie/scope.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package trie

import (
	"strconv"
	"sync/atomic"
)

// Scope represents a distinct collection of maps.
// Maps with the same Scope can be equal. Maps in different scopes are distinct.
// Each Builder creates maps within a unique Scope.
type Scope struct {
	id int32
}

var nextScopeId int32

func newScope() Scope {
	id := atomic.AddInt32(&nextScopeId, 1)
	return Scope{id: id}
}

func (s Scope) String() string {
	return strconv.Itoa(int(s.id))
}


================================================
FILE: go/callgraph/vta/internal/trie/trie.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// trie implements persistent Patricia trie maps.
//
// Each Map is effectively a map from uint64 to interface{}. Patricia tries are
// a form of radix tree that are particularly appropriate when many maps will be
// created, merged together and large amounts of sharing are expected (e.g.
// environment abstract domains in program analysis).
//
// This implementation closely follows the paper:
//
//	C. Okasaki and A. Gill, “Fast mergeable integer maps,” in ACM SIGPLAN
//	Workshop on ML, September 1998, pp. 77–86.
//
// Each Map is immutable and can be read from concurrently. The map does not
// guarantee that the value pointed to by the interface{} value is not updated
// concurrently.
//
// These Maps are optimized for situations where there will be many maps created at
// with a high degree of sharing and combining of maps together. If you do not expect,
// significant amount of sharing, the builtin map[T]U is much better choice!
//
// Each Map is created by a Builder. Each Builder has a unique Scope and each node is
// created within this scope. Maps x and y are == if they contains the same
// (key,value) mappings and have equal scopes.
//
// Internally these are big endian Patricia trie nodes, and the keys are sorted.
package trie

import (
	"fmt"
	"strings"
)

// Map is effectively a finite mapping from uint64 keys to interface{} values.
// Maps are immutable and can be read from concurrently.
//
// Notes on concurrency:
//   - A Map value itself is an interface and assignments to a Map value can race.
//   - Map does not guarantee that the value pointed to by the interface{} value
//     is not updated concurrently.
type Map struct {
	s Scope
	n node
}

func (m Map) Scope() Scope {
	return m.s
}
func (m Map) Size() int {
	if m.n == nil {
		return 0
	}
	return m.n.size()
}
func (m Map) Lookup(k uint64) (any, bool) {
	if m.n != nil {
		if leaf := m.n.find(key(k)); leaf != nil {
			return leaf.v, true
		}
	}
	return nil, false
}

// Converts the map into a {<key>: <value>[, ...]} string. This uses the default
// %s string conversion for <value>.
func (m Map) String() string {
	var kvs []string
	m.Range(func(u uint64, i any) bool {
		kvs = append(kvs, fmt.Sprintf("%d: %s", u, i))
		return true
	})
	return fmt.Sprintf("{%s}", strings.Join(kvs, ", "))
}

// Range over the leaf (key, value) pairs in the map in order and
// applies cb(key, value) to each. Stops early if cb returns false.
// Returns true if all elements were visited without stopping early.
func (m Map) Range(cb func(uint64, any) bool) bool {
	if m.n != nil {
		return m.n.visit(cb)
	}
	return true
}

// DeepEqual returns true if m and other contain the same (k, v) mappings
// [regardless of Scope].
//
// Equivalently m.DeepEqual(other) <=> reflect.DeepEqual(Elems(m), Elems(other))
func (m Map) DeepEqual(other Map) bool {
	if m.Scope() == other.Scope() {
		return m.n == other.n
	}
	if (m.n == nil) || (other.n == nil) {
		return m.Size() == 0 && other.Size() == 0
	}
	return m.n.deepEqual(other.n)
}

// Elems are the (k,v) elements in the Map as a map[uint64]interface{}
func Elems(m Map) map[uint64]any {
	dest := make(map[uint64]any, m.Size())
	m.Range(func(k uint64, v any) bool {
		dest[k] = v
		return true
	})
	return dest
}

// node is an internal node within a trie map.
// A node is either empty, a leaf or a branch.
type node interface {
	size() int

	// visit the leaves (key, value) pairs in the map in order and
	// applies cb(key, value) to each. Stops early if cb returns false.
	// Returns true if all elements were visited without stopping early.
	visit(cb func(uint64, any) bool) bool

	// Two nodes contain the same elements regardless of scope.
	deepEqual(node) bool

	// find the leaf for the given key value or nil if it is not present.
	find(k key) *leaf

	// implementations must implement this.
	nodeImpl()
}

// empty represents the empty map within a scope.
//
// The current builder ensure
type empty struct {
	s Scope
}

// leaf represents a single <key, value> pair.
type leaf struct {
	k key
	v any
}

// branch represents a tree node within the Patricia trie.
//
// All keys within the branch match a `prefix` of the key
// up to a `branching` bit, and the left and right nodes
// contain keys that disagree on the bit at the `branching` bit.
type branch struct {
	sz        int    // size. cached for O(1) lookup
	prefix    prefix // == mask(p0, branching) for some p0
	branching bitpos

	// Invariants:
	// - neither is nil.
	// - neither is *empty.
	// - all keys in left are <= p.
	// - all keys in right are > p.
	left, right node
}

// all of these types are Maps.
var _ node = &empty{}
var _ node = &leaf{}
var _ node = &branch{}

func (*empty) nodeImpl()  {}
func (*leaf) nodeImpl()   {}
func (*branch) nodeImpl() {}

func (*empty) find(k key) *leaf { return nil }
func (l *leaf) find(k key) *leaf {
	if k == l.k {
		return l
	}
	return nil
}
func (br *branch) find(k key) *leaf {
	kp := prefix(k)
	if !matchPrefix(kp, br.prefix, br.branching) {
		return nil
	}
	if zeroBit(kp, br.branching) {
		return br.left.find(k)
	}
	return br.right.find(k)
}

func (*empty) size() int     { return 0 }
func (*leaf) size() int      { return 1 }
func (br *branch) size() int { return br.sz }

func (*empty) deepEqual(m node) bool {
	_, ok := m.(*empty)
	return ok
}
func (l *leaf) deepEqual(m node) bool {
	if m, ok := m.(*leaf); ok {
		return m == l || (l.k == m.k && l.v == m.v)
	}
	return false
}

func (br *branch) deepEqual(m node) bool {
	if m, ok := m.(*branch); ok {
		if br == m {
			return true
		}
		return br.sz == m.sz && br.branching == m.branching && br.prefix == m.prefix &&
			br.left.deepEqual(m.left) && br.right.deepEqual(m.right)
	}
	// if m is not a branch, m contains 0 or 1 elem.
	// br contains at least 2 keys that disagree on a prefix.
	return false
}

func (*empty) visit(cb func(uint64, any) bool) bool {
	return true
}
func (l *leaf) visit(cb func(uint64, any) bool) bool {
	return cb(uint64(l.k), l.v)
}
func (br *branch) visit(cb func(uint64, any) bool) bool {
	if !br.left.visit(cb) {
		return false
	}
	return br.right.visit(cb)
}


================================================
FILE: go/callgraph/vta/internal/trie/trie_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.13

package trie

import (
	"reflect"
	"strconv"
	"testing"
)

func TestScope(t *testing.T) {
	def := Scope{}
	s0, s1 := newScope(), newScope()
	if s0 == def || s1 == def {
		t.Error("newScope() should never be == to the default scope")
	}
	if s0 == s1 {
		t.Errorf("newScope() %q and %q should not be ==", s0, s1)
	}
	if s0.id == 0 {
		t.Error("s0.id is 0")
	}
	if s1.id == 0 {
		t.Error("s1.id is 0")
	}
	got := s0.String()
	if _, err := strconv.Atoi(got); err != nil {
		t.Errorf("scope{%s}.String() is not an int: got %s with error %s", s0, got, err)
	}
}

func TestCollision(t *testing.T) {
	var x any = 1
	var y any = 2

	if v := TakeLhs(x, y); v != x {
		t.Errorf("TakeLhs(%s, %s) got %s. want %s", x, y, v, x)
	}
	if v := TakeRhs(x, y); v != y {
		t.Errorf("TakeRhs(%s, %s) got %s. want %s", x, y, v, y)
	}
}

func TestDefault(t *testing.T) {
	def := Map{}

	if def.Size() != 0 {
		t.Errorf("default node has non-0 size %d", def.Size())
	}
	if want, got := (Scope{}), def.Scope(); got != want {
		t.Errorf("default is in a non default scope (%s) from b (%s)", got, want)
	}
	if v, ok := def.Lookup(123); !(v == nil && !ok) {
		t.Errorf("Scope{}.Lookup() = (%s, %v) not (nil, false)", v, ok)
	}
	if !def.Range(func(k uint64, v any) bool {
		t.Errorf("Scope{}.Range() called it callback on %d:%s", k, v)
		return true
	}) {
		t.Error("Scope{}.Range() always iterates through all elements")
	}

	if got, want := def.String(), "{}"; got != want {
		t.Errorf("Scope{}.String() got %s. want %s", got, want)
	}

	b := NewBuilder()
	if def == b.Empty() {
		t.Error("Scope{} == to an empty node from a builder")
	}
	if b.Clone(def) != b.Empty() {
		t.Error("b.Clone(Scope{}) should equal b.Empty()")
	}
	if !def.DeepEqual(b.Empty()) {
		t.Error("Scope{}.DeepEqual(b.Empty()) should hold")
	}
}

func TestBuilders(t *testing.T) {
	b0, b1 := NewBuilder(), NewBuilder()
	if b0.Scope() == b1.Scope() {
		t.Errorf("builders have the same scope %s", b0.Scope())
	}

	if b0.Empty() == b1.Empty() {
		t.Errorf("empty nodes from different scopes are disequal")
	}
	if !b0.Empty().DeepEqual(b1.Empty()) {
		t.Errorf("empty nodes from different scopes are not DeepEqual")
	}

	clone := b1.Clone(b0.Empty())
	if clone != b1.Empty() {
		t.Errorf("Clone() empty nodes %v != %v", clone, b1.Empty())
	}
}

func TestEmpty(t *testing.T) {
	b := NewBuilder()
	e := b.Empty()
	if e.Size() != 0 {
		t.Errorf("empty nodes has non-0 size %d", e.Size())
	}
	if e.Scope() != b.Scope() {
		t.Errorf("b.Empty() is in a different scope (%s) from b (%s)", e.Scope(), b.Scope())
	}
	if v, ok := e.Lookup(123); !(v == nil && !ok) {
		t.Errorf("empty.Lookup() = (%s, %v) not (nil, false)", v, ok)
	}
	if l := e.n.find(123); l != nil {
		t.Errorf("empty.find(123) got %v. want nil", l)
	}
	e.Range(func(k uint64, v any) bool {
		t.Errorf("empty.Range() called it callback on %d:%s", k, v)
		return true
	})

	want := "{}"
	if got := e.String(); got != want {
		t.Errorf("empty.String(123) got %s. want %s", got, want)
	}
}

func TestCreate(t *testing.T) {
	// The node orders are printed in lexicographic little-endian.
	b := NewBuilder()
	for _, c := range []struct {
		m    map[uint64]any
		want string
	}{
		{
			map[uint64]any{},
			"{}",
		},
		{
			map[uint64]any{1: "a"},
			"{1: a}",
		},
		{
			map[uint64]any{2: "b", 1: "a"},
			"{1: a, 2: b}",
		},
		{
			map[uint64]any{1: "x", 4: "y", 5: "z"},
			"{1: x, 4: y, 5: z}",
		},
	} {
		m := b.Create(c.m)
		if got := m.String(); got != c.want {
			t.Errorf("Create(%v) got %q. want %q ", c.m, got, c.want)
		}
	}
}

func TestElems(t *testing.T) {
	b := NewBuilder()
	for _, orig := range []map[uint64]any{
		{},
		{1: "a"},
		{1: "a", 2: "b"},
		{1: "x", 4: "y", 5: "z"},
		{1: "x", 4: "y", 5: "z", 123: "abc"},
	} {
		m := b.Create(orig)
		if elems := Elems(m); !reflect.DeepEqual(orig, elems) {
			t.Errorf("Elems(%v) got %q. want %q ", m, elems, orig)
		}
	}
}

func TestRange(t *testing.T) {
	b := NewBuilder()
	m := b.Create(map[uint64]any{1: "x", 3: "y", 5: "z", 6: "stop", 8: "a"})

	calls := 0
	cb := func(k uint64, v any) bool {
		t.Logf("visiting (%d, %v)", k, v)
		calls++
		return k%2 != 0 // stop after the first even number.
	}
	// The nodes are visited in increasing order.
	all := m.Range(cb)
	if all {
		t.Error("expected to stop early")
	}
	want := 4
	if calls != want {
		t.Errorf("# of callbacks (%d) was expected to equal %d (1 + # of evens)",
			calls, want)
	}
}

func TestDeepEqual(t *testing.T) {
	for _, m := range []map[uint64]any{
		{},
		{1: "x"},
		{1: "x", 2: "y"},
	} {
		l := NewBuilder().Create(m)
		r := NewBuilder().Create(m)
		if !l.DeepEqual(r) {
			t.Errorf("Expect %v to be DeepEqual() to %v", l, r)
		}
	}
}

func TestNotDeepEqual(t *testing.T) {
	for _, c := range []struct {
		left  map[uint64]any
		right map[uint64]any
	}{
		{
			map[uint64]any{1: "x"},
			map[uint64]any{},
		},
		{
			map[uint64]any{},
			map[uint64]any{1: "y"},
		},
		{
			map[uint64]any{1: "x"},
			map[uint64]any{1: "y"},
		},
		{
			map[uint64]any{1: "x"},
			map[uint64]any{1: "x", 2: "Y"},
		},
		{
			map[uint64]any{1: "x", 2: "Y"},
			map[uint64]any{1: "x"},
		},
		{
			map[uint64]any{1: "x", 2: "y"},
			map[uint64]any{1: "x", 2: "Y"},
		},
	} {
		l := NewBuilder().Create(c.left)
		r := NewBuilder().Create(c.right)
		if l.DeepEqual(r) {
			t.Errorf("Expect %v to be !DeepEqual() to %v", l, r)
		}
	}
}

func TestMerge(t *testing.T) {
	b := NewBuilder()
	for _, c := range []struct {
		left  map[uint64]any
		right map[uint64]any
		want  string
	}{
		{
			map[uint64]any{},
			map[uint64]any{},
			"{}",
		},
		{
			map[uint64]any{},
			map[uint64]any{1: "a"},
			"{1: a}",
		},
		{
			map[uint64]any{1: "a"},
			map[uint64]any{},
			"{1: a}",
		},
		{
			map[uint64]any{1: "a", 2: "b"},
			map[uint64]any{},
			"{1: a, 2: b}",
		},
		{
			map[uint64]any{1: "x"},
			map[uint64]any{1: "y"},
			"{1: x}", // default collision is left
		},
		{
			map[uint64]any{1: "x"},
			map[uint64]any{2: "y"},
			"{1: x, 2: y}",
		},
		{
			map[uint64]any{4: "y", 5: "z"},
			map[uint64]any{1: "x"},
			"{1: x, 4: y, 5: z}",
		},
		{
			map[uint64]any{1: "x", 5: "z"},
			map[uint64]any{4: "y"},
			"{1: x, 4: y, 5: z}",
		},
		{
			map[uint64]any{1: "x", 4: "y"},
			map[uint64]any{5: "z"},
			"{1: x, 4: y, 5: z}",
		},
		{
			map[uint64]any{1: "a", 4: "c"},
			map[uint64]any{2: "b", 5: "d"},
			"{1: a, 2: b, 4: c, 5: d}",
		},
		{
			map[uint64]any{1: "a", 4: "c"},
			map[uint64]any{2: "b", 5 + 8: "d"},
			"{1: a, 2: b, 4: c, 13: d}",
		},
		{
			map[uint64]any{2: "b", 5 + 8: "d"},
			map[uint64]any{1: "a", 4: "c"},
			"{1: a, 2: b, 4: c, 13: d}",
		},
		{
			map[uint64]any{1: "a", 4: "c"},
			map[uint64]any{2: "b", 5 + 8: "d"},
			"{1: a, 2: b, 4: c, 13: d}",
		},
		{
			map[uint64]any{2: "b", 5 + 8: "d"},
			map[uint64]any{1: "a", 4: "c"},
			"{1: a, 2: b, 4: c, 13: d}",
		},
		{
			map[uint64]any{2: "b", 5 + 8: "d"},
			map[uint64]any{2: "", 3: "a"},
			"{2: b, 3: a, 13: d}",
		},

		{
			// crafted for `!prefixesOverlap(p, m, q, n)`
			left:  map[uint64]any{1: "a", 2 + 1: "b"},
			right: map[uint64]any{4 + 1: "c", 4 + 2: "d"},
			// p: 5, m: 2 q: 1, n: 2
			want: "{1: a, 3: b, 5: c, 6: d}",
		},
		{
			// crafted for `ord(m, n) && !zeroBit(q, m)`
			left:  map[uint64]any{8 + 2 + 1: "a", 16 + 4: "b"},
			right: map[uint64]any{16 + 8 + 2 + 1: "c", 16 + 8 + 4 + 2 + 1: "d"},
			// left: p: 15, m: 16
			// right: q: 27, n: 4
			want: "{11: a, 20: b, 27: c, 31: d}",
		},
		{
			// crafted for `ord(n, m) && !zeroBit(p, n)`
			// p: 6, m: 1 q: 5, n: 2
			left:  map[uint64]any{4 + 2: "b", 4 + 2 + 1: "c"},
			right: map[uint64]any{4: "a", 4 + 2 + 1: "dropped"},
			want:  "{4: a, 6: b, 7: c}",
		},
	} {
		l, r := b.Create(c.left), b.Create(c.right)
		m := b.Merge(l, r)
		if got := m.String(); got != c.want {
			t.Errorf("Merge(%s, %s) got %q. want %q ", l, r, got, c.want)
		}
	}
}

func TestIntersect(t *testing.T) {
	// Most of the test cases go after specific branches of intersect.
	b := NewBuilder()
	for _, c := range []struct {
		left  map[uint64]any
		right map[uint64]any
		want  string
	}{
		{
			left:  map[uint64]any{10: "a", 39: "b"},
			right: map[uint64]any{10: "A", 39: "B", 75: "C"},
			want:  "{10: a, 39: b}",
		},
		{
			left:  map[uint64]any{10: "a", 39: "b"},
			right: map[uint64]any{},
			want:  "{}",
		},
		{
			left:  map[uint64]any{},
			right: map[uint64]any{10: "A", 39: "B", 75: "C"},
			want:  "{}",
		},
		{ // m == n && p == q  && left.(*empty) case
			left:  map[uint64]any{4: 1, 6: 3, 10: 8, 15: "on left"},
			right: map[uint64]any{0: 8, 7: 6, 11: 0, 15: "on right"},
			want:  "{15: on left}",
		},
		{ // m == n && p == q  && right.(*empty) case
			left:  map[uint64]any{0: "on left", 1: 2, 2: 3, 3: 1, 7: 3},
			right: map[uint64]any{0: "on right", 5: 1, 6: 8},
			want:  "{0: on left}",
		},
		{ // m == n && p == q  &&  both left and right are not empty
			left:  map[uint64]any{1: "a", 2: "b", 3: "c"},
			right: map[uint64]any{0: "A", 1: "B", 2: "C"},
			want:  "{1: a, 2: b}",
		},
		{ // m == n && p == q  &&  both left and right are not empty
			left:  map[uint64]any{1: "a", 2: "b", 3: "c"},
			right: map[uint64]any{0: "A", 1: "B", 2: "C"},
			want:  "{1: a, 2: b}",
		},
		{ // !prefixesOverlap(p, m, q, n)
			// p = 1, m = 2, q = 5, n = 2
			left:  map[uint64]any{0b001: 1, 0b011: 3},
			right: map[uint64]any{0b100: 4, 0b111: 7},
			want:  "{}",
		},
		{ // ord(m, n) && zeroBit(q, m)
			// p = 3, m = 4, q = 0, n = 1
			left:  map[uint64]any{0b010: 2, 0b101: 5},
			right: map[uint64]any{0b000: 0, 0b001: 1},
			want:  "{}",
		},

		{ // ord(m, n) && !zeroBit(q, m)
			// p = 29, m = 2, q = 30, n = 1
			left: map[uint64]any{
				0b11101: "29",
				0b11110: "30",
			},
			right: map[uint64]any{
				0b11110: "30 on right",
				0b11111: "31",
			},
			want: "{30: 30}",
		},
		{ // ord(n, m) && zeroBit(p, n)
			// p = 5, m = 2, q = 3, n = 4
			left:  map[uint64]any{0b000: 0, 0b001: 1},
			right: map[uint64]any{0b010: 2, 0b101: 5},
			want:  "{}",
		},
		{ // default case
			// p = 5, m = 2, q = 3, n = 4
			left:  map[uint64]any{0b100: 1, 0b110: 3},
			right: map[uint64]any{0b000: 8, 0b111: 6},
			want:  "{}",
		},
	} {
		l, r := b.Create(c.left), b.Create(c.right)
		m := b.Intersect(l, r)
		if got := m.String(); got != c.want {
			t.Errorf("Intersect(%s, %s) got %q. want %q ", l, r, got, c.want)
		}
	}
}

func TestIntersectWith(t *testing.T) {
	b := NewBuilder()
	l := b.Create(map[uint64]any{10: 2.0, 39: 32.0})
	r := b.Create(map[uint64]any{10: 6.0, 39: 10.0, 75: 1.0})

	prodIfDifferent := func(x any, y any) any {
		if x, ok := x.(float64); ok {
			if y, ok := y.(float64); ok {
				if x == y {
					return x
				}
				return x * y
			}
		}
		return x
	}

	m := b.IntersectWith(prodIfDifferent, l, r)

	want := "{10: %!s(float64=12), 39: %!s(float64=320)}"
	if got := m.String(); got != want {
		t.Errorf("IntersectWith(min, %s, %s) got %q. want %q ", l, r, got, want)
	}
}

func TestRemove(t *testing.T) {
	// Most of the test cases go after specific branches of intersect.
	b := NewBuilder()
	for _, c := range []struct {
		m    map[uint64]any
		key  uint64
		want string
	}{
		{map[uint64]any{}, 10, "{}"},
		{map[uint64]any{10: "a"}, 10, "{}"},
		{map[uint64]any{39: "b"}, 10, "{39: b}"},
		// Branch cases:
		// !matchPrefix(kp, br.prefix, br.branching)
		{map[uint64]any{10: "a", 39: "b"}, 128, "{10: a, 39: b}"},
		// case: left == br.left && right == br.right
		{map[uint64]any{10: "a", 39: "b"}, 16, "{10: a, 39: b}"},
		// left updated and is empty.
		{map[uint64]any{10: "a", 39: "b"}, 10, "{39: b}"},
		// right updated and is empty.
		{map[uint64]any{10: "a", 39: "b"}, 39, "{10: a}"},
		// final b.mkBranch(...) case.
		{map[uint64]any{10: "a", 39: "b", 128: "c"}, 39, "{10: a, 128: c}"},
	} {
		pre := b.Create(c.m)
		post := b.Remove(pre, c.key)
		if got := post.String(); got != c.want {
			t.Errorf("Remove(%s, %d) got %q. want %q ", pre, c.key, got, c.want)
		}
	}
}

func TestRescope(t *testing.T) {
	b := NewBuilder()
	l := b.Create(map[uint64]any{10: "a", 39: "b"})
	r := b.Create(map[uint64]any{10: "A", 39: "B", 75: "C"})

	b.Rescope()

	m := b.Intersect(l, r)
	if got, want := m.String(), "{10: a, 39: b}"; got != want {
		t.Errorf("Intersect(%s, %s) got %q. want %q", l, r, got, want)
	}
	if m.Scope() == l.Scope() {
		t.Errorf("m.Scope() = %v should not equal l.Scope() = %v", m.Scope(), l.Scope())
	}
	if m.Scope() == r.Scope() {
		t.Errorf("m.Scope() = %v should not equal r.Scope() = %v", m.Scope(), r.Scope())
	}
}

func TestSharing(t *testing.T) {
	b := NewBuilder()
	l := b.Create(map[uint64]any{0: "a", 1: "b"})
	r := b.Create(map[uint64]any{1: "B", 2: "C"})

	rleftold := r.n.(*branch).left

	m := b.Merge(l, r)
	if mleft := m.n.(*branch).left; mleft != l.n {
		t.Errorf("unexpected value for left branch of %v. want %v got %v", m, l, mleft)
	}

	if rleftnow := r.n.(*branch).left; rleftnow != rleftold {
		t.Errorf("r.n.(*branch).left was modified by the Merge operation. was %v now %v", rleftold, rleftnow)
	}
}


================================================
FILE: go/callgraph/vta/propagation.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"go/types"
	"iter"
	"slices"

	"golang.org/x/tools/go/callgraph/vta/internal/trie"
	"golang.org/x/tools/go/ssa"

	"golang.org/x/tools/go/types/typeutil"
)

// scc computes strongly connected components (SCCs) of `g` using the
// classical Tarjan's algorithm for SCCs. The result is two slices:
//   - sccs: the SCCs, each represented as a slice of node indices
//   - idxToSccID: the inverse map, from node index to SCC number.
//
// The SCCs are sorted in reverse topological order: for SCCs
// with ids X and Y s.t. X < Y, Y comes before X in the topological order.
func scc(g *vtaGraph) (sccs [][]idx, idxToSccID []int) {
	// standard data structures used by Tarjan's algorithm.
	type state struct {
		pre     int // preorder of the node (0 if unvisited)
		lowLink int
		onStack bool
	}
	states := make([]state, g.numNodes())
	var stack []idx

	idxToSccID = make([]int, g.numNodes())
	nextPre := 0

	var doSCC func(idx)
	doSCC = func(n idx) {
		nextPre++
		ns := &states[n]
		*ns = state{pre: nextPre, lowLink: nextPre, onStack: true}
		stack = append(stack, n)

		for s := range g.successors(n) {
			if ss := &states[s]; ss.pre == 0 {
				// Analyze successor s that has not been visited yet.
				doSCC(s)
				ns.lowLink = min(ns.lowLink, ss.lowLink)
			} else if ss.onStack {
				// The successor is on the stack, meaning it has to be
				// in the current SCC.
				ns.lowLink = min(ns.lowLink, ss.pre)
			}
		}

		// if n is a root node, pop the stack and generate a new SCC.
		if ns.lowLink == ns.pre {
			sccStart := slicesLastIndex(stack, n)
			scc := slices.Clone(stack[sccStart:])
			stack = stack[:sccStart]
			sccID := len(sccs)
			sccs = append(sccs, scc)
			for _, w := range scc {
				states[w].onStack = false
				idxToSccID[w] = sccID
			}
		}
	}

	for n, nn := 0, g.numNodes(); n < nn; n++ {
		if states[n].pre == 0 {
			doSCC(idx(n))
		}
	}

	return sccs, idxToSccID
}

// slicesLastIndex returns the index of the last occurrence of v in s, or -1 if v is
// not present in s.
//
// slicesLastIndex iterates backwards through the elements of s, stopping when the ==
// operator determines an element is equal to v.
func slicesLastIndex[S ~[]E, E comparable](s S, v E) int {
	// TODO: move to / dedup with slices.LastIndex
	for i := len(s) - 1; i >= 0; i-- {
		if s[i] == v {
			return i
		}
	}
	return -1
}

// propType represents type information being propagated
// over the vta graph. f != nil only for function nodes
// and nodes reachable from function nodes. There, we also
// remember the actual *ssa.Function in order to more
// precisely model higher-order flow.
type propType struct {
	typ types.Type
	f   *ssa.Function
}

// propTypeMap is an auxiliary structure that serves
// the role of a map from nodes to a set of propTypes.
type propTypeMap map[node]*trie.MutMap

// propTypes returns an iterator for the propTypes associated with
// node `n` in map `ptm`.
func (ptm propTypeMap) propTypes(n node) iter.Seq[propType] {
	return func(yield func(propType) bool) {
		if types := ptm[n]; types != nil {
			types.M.Range(func(_ uint64, elem any) bool {
				return yield(elem.(propType))
			})
		}
	}
}

// propagate reduces the `graph` based on its SCCs and
// then propagates type information through the reduced
// graph. The result is a map from nodes to a set of types
// and functions, stemming from higher-order data flow,
// reaching the node. `canon` is used for type uniqueness.
func propagate(graph *vtaGraph, canon *typeutil.Map) propTypeMap {
	sccs, idxToSccID := scc(graph)

	// propTypeIds are used to create unique ids for
	// propType, to be used for trie-based type sets.
	propTypeIds := make(map[propType]uint64)
	// Id creation is based on == equality, which works
	// as types are canonicalized (see getPropType).
	propTypeId := func(p propType) uint64 {
		if id, ok := propTypeIds[p]; ok {
			return id
		}
		id := uint64(len(propTypeIds))
		propTypeIds[p] = id
		return id
	}
	builder := trie.NewBuilder()
	// Initialize sccToTypes to avoid repeated check
	// for initialization later.
	sccToTypes := make([]*trie.MutMap, len(sccs))
	for sccID, scc := range sccs {
		typeSet := builder.MutEmpty()
		for _, idx := range scc {
			if n := graph.node[idx]; hasInitialTypes(n) {
				// add the propType for idx to typeSet.
				pt := getPropType(n, canon)
				typeSet.Update(propTypeId(pt), pt)
			}
		}
		sccToTypes[sccID] = &typeSet
	}

	for i := len(sccs) - 1; i >= 0; i-- {
		nextSccs := make(map[int]empty)
		for _, n := range sccs[i] {
			for succ := range graph.successors(n) {
				nextSccs[idxToSccID[succ]] = empty{}
			}
		}
		// Propagate types to all successor SCCs.
		for nextScc := range nextSccs {
			sccToTypes[nextScc].Merge(sccToTypes[i].M)
		}
	}
	nodeToTypes := make(propTypeMap, graph.numNodes())
	for sccID, scc := range sccs {
		types := sccToTypes[sccID]
		for _, idx := range scc {
			nodeToTypes[graph.node[idx]] = types
		}
	}
	return nodeToTypes
}

// hasInitialTypes check if a node can have initial types.
// Returns true iff `n` is not a panic, recover, nestedPtr*
// node, nor a node whose type is an interface.
func hasInitialTypes(n node) bool {
	switch n.(type) {
	case panicArg, recoverReturn, nestedPtrFunction, nestedPtrInterface:
		return false
	default:
		return !types.IsInterface(n.Type())
	}
}

// getPropType creates a propType for `node` based on its type.
// propType.typ is always node.Type(). If node is function, then
// propType.val is the underlying function; nil otherwise.
func getPropType(node node, canon *typeutil.Map) propType {
	t := canonicalize(node.Type(), canon)
	if fn, ok := node.(function); ok {
		return propType{f: fn.f, typ: t}
	}
	return propType{f: nil, typ: t}
}


================================================
FILE: go/callgraph/vta/propagation_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"go/token"
	"go/types"
	"math"
	"reflect"
	"slices"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"

	"golang.org/x/tools/go/types/typeutil"
)

// val is a test data structure for creating ssa.Value
// outside of the ssa package. Needed for manual creation
// of vta graph nodes in testing.
type val struct {
	name string
	typ  types.Type
}

func (v val) String() string {
	return v.name
}

func (v val) Name() string {
	return v.name
}

func (v val) Type() types.Type {
	return v.typ
}

func (v val) Parent() *ssa.Function {
	return nil
}

func (v val) Referrers() *[]ssa.Instruction {
	return nil
}

func (v val) Pos() token.Pos {
	return token.NoPos
}

// newLocal creates a new local node with ssa.Value
// named `name` and type `t`.
func newLocal(name string, t types.Type) local {
	return local{val: val{name: name, typ: t}}
}

// sccString is a utility for stringifying `nodeToScc`. Every
// scc is represented as a string where string representation
// of scc nodes are sorted and concatenated using `;`.
func sccString(sccs [][]idx, g *vtaGraph) []string {
	var sccsStr []string
	for _, scc := range sccs {
		var nodesStr []string
		for _, idx := range scc {
			nodesStr = append(nodesStr, g.node[idx].String())
		}
		sort.Strings(nodesStr)
		sccsStr = append(sccsStr, strings.Join(nodesStr, ";"))
	}
	return sccsStr
}

// nodeToTypeString is testing utility for stringifying results
// of type propagation: propTypeMap `pMap` is converted to a map
// from node strings to a string consisting of type stringifications
// concatenated with `;`. We stringify reachable type information
// that also has an accompanying function by the function name.
func nodeToTypeString(pMap propTypeMap) map[string]string {
	// Convert propType to a string. If propType has
	// an attached function, return the function name.
	// Otherwise, return the type name.
	propTypeString := func(p propType) string {
		if p.f != nil {
			return p.f.Name()
		}
		return p.typ.String()
	}

	nodeToTypeStr := make(map[string]string)
	for node := range pMap {
		var propStrings []string
		for prop := range pMap.propTypes(node) {
			s := propTypeString(prop)
			s = strings.ReplaceAll(s, "example.com.", "")
			propStrings = append(propStrings, s)
		}
		sort.Strings(propStrings)
		nodeToTypeStr[node.String()] = strings.Join(propStrings, ";")
	}

	return nodeToTypeStr
}

// sccEqual compares two sets of SCC stringifications.
func sccEqual(sccs1 []string, sccs2 []string) bool {
	if len(sccs1) != len(sccs2) {
		return false
	}
	sort.Strings(sccs1)
	sort.Strings(sccs2)
	return reflect.DeepEqual(sccs1, sccs2)
}

// isRevTopSorted checks if sccs of `g` are sorted in reverse
// topological order:
//
//	for every edge x -> y in g, nodeToScc[x] > nodeToScc[y]
func isRevTopSorted(g *vtaGraph, idxToScc []int) bool {
	for n := range idxToScc {
		for s := range g.successors(idx(n)) {
			if idxToScc[n] < idxToScc[s] {
				return false
			}
		}
	}
	return true
}

func sccMapsConsistent(sccs [][]idx, idxToSccID []int) bool {
	for id, scc := range sccs {
		for _, idx := range scc {
			if idxToSccID[idx] != id {
				return false
			}
		}
	}
	for i, id := range idxToSccID {
		if !slices.Contains(sccs[id], idx(i)) {
			return false
		}
	}
	return true
}

// testSuite produces a named set of graphs as follows, where
// parentheses contain node types and F nodes stand for function
// nodes whose content is function named F:
//
//	 no-cycles:
//		t0 (A) -> t1 (B) -> t2 (C)
//
//	 trivial-cycle:
//	     <--------    <--------
//	     |       |    |       |
//	     t0 (A) ->    t1 (B) ->
//
//	 circle-cycle:
//		t0 (A) -> t1 (A) -> t2 (B)
//	     |                   |
//	     <--------------------
//
//	 fully-connected:
//		t0 (A) <-> t1 (B)
//	          \    /
//	           t2(C)
//
//	 subsumed-scc:
//		t0 (A) -> t1 (B) -> t2(B) -> t3 (A)
//	     |          |         |        |
//	     |          <---------         |
//	     <-----------------------------
//
//	 more-realistic:
//	     <--------
//	     |        |
//	     t0 (A) -->
//	                           ---------->
//	                          |           |
//	     t1 (A) -> t2 (B) -> F1 -> F2 -> F3 -> F4
//	      |        |          |           |
//	       <-------           <------------
func testSuite(t *testing.T) map[string]*vtaGraph {
	ar := txtar.Parse([]byte(`-- go.mod --
module example.com
go 1.24

-- p.go --
package p
type A struct{}
type B struct{}
type C struct{}
func F1()
func F2()
func F3()
func F4()
`))
	ppkgs := testfiles.LoadPackages(t, ar, ".")
	if len(ppkgs) != 1 {
		t.Fatalf("LoadPackages returned %d packages, want 1", len(ppkgs))
	}
	_, ssapkgs := ssautil.Packages(ppkgs, ssa.BuilderMode(0))
	pkg := ssapkgs[0]

	a := pkg.Type("A").Type().(*types.Named)
	b := pkg.Type("B").Type().(*types.Named)
	c := pkg.Type("C").Type().(*types.Named)
	f1 := pkg.Func("F1")
	f2 := pkg.Func("F2")
	f3 := pkg.Func("F3")
	f4 := pkg.Func("F4")

	graphs := make(map[string]*vtaGraph)
	v := &vtaGraph{}
	graphs["no-cycles"] = v
	v.addEdge(newLocal("t0", a), newLocal("t1", b))
	v.addEdge(newLocal("t1", b), newLocal("t2", c))

	v = &vtaGraph{}
	graphs["trivial-cycle"] = v
	v.addEdge(newLocal("t0", a), newLocal("t0", a))
	v.addEdge(newLocal("t1", b), newLocal("t1", b))

	v = &vtaGraph{}
	graphs["circle-cycle"] = v
	v.addEdge(newLocal("t0", a), newLocal("t1", a))
	v.addEdge(newLocal("t1", a), newLocal("t2", b))
	v.addEdge(newLocal("t2", b), newLocal("t0", a))

	v = &vtaGraph{}
	graphs["fully-connected"] = v
	v.addEdge(newLocal("t0", a), newLocal("t1", b))
	v.addEdge(newLocal("t0", a), newLocal("t2", c))
	v.addEdge(newLocal("t1", b), newLocal("t0", a))
	v.addEdge(newLocal("t1", b), newLocal("t2", c))
	v.addEdge(newLocal("t2", c), newLocal("t0", a))
	v.addEdge(newLocal("t2", c), newLocal("t1", b))

	v = &vtaGraph{}
	graphs["subsumed-scc"] = v
	v.addEdge(newLocal("t0", a), newLocal("t1", b))
	v.addEdge(newLocal("t1", b), newLocal("t2", b))
	v.addEdge(newLocal("t2", b), newLocal("t1", b))
	v.addEdge(newLocal("t2", b), newLocal("t3", a))
	v.addEdge(newLocal("t3", a), newLocal("t0", a))

	v = &vtaGraph{}
	graphs["more-realistic"] = v
	v.addEdge(newLocal("t0", a), newLocal("t0", a))
	v.addEdge(newLocal("t1", a), newLocal("t2", b))
	v.addEdge(newLocal("t2", b), newLocal("t1", a))
	v.addEdge(newLocal("t2", b), function{f1})
	v.addEdge(function{f1}, function{f2})
	v.addEdge(function{f1}, function{f3})
	v.addEdge(function{f2}, function{f3})
	v.addEdge(function{f3}, function{f1})
	v.addEdge(function{f3}, function{f4})

	return graphs
}

func TestSCC(t *testing.T) {
	suite := testSuite(t)
	for _, test := range []struct {
		name  string
		graph *vtaGraph
		want  []string
	}{
		// No cycles results in three separate SCCs: {t0}	{t1}	{t2}
		{name: "no-cycles", graph: suite["no-cycles"], want: []string{"Local(t0)", "Local(t1)", "Local(t2)"}},
		// The two trivial self-loop cycles results in: {t0}	{t1}
		{name: "trivial-cycle", graph: suite["trivial-cycle"], want: []string{"Local(t0)", "Local(t1)"}},
		// The circle cycle produce a single SCC: {t0, t1, t2}
		{name: "circle-cycle", graph: suite["circle-cycle"], want: []string{"Local(t0);Local(t1);Local(t2)"}},
		// Similar holds for fully connected SCC: {t0, t1, t2}
		{name: "fully-connected", graph: suite["fully-connected"], want: []string{"Local(t0);Local(t1);Local(t2)"}},
		// Subsumed SCC also has a single SCC: {t0, t1, t2, t3}
		{name: "subsumed-scc", graph: suite["subsumed-scc"], want: []string{"Local(t0);Local(t1);Local(t2);Local(t3)"}},
		// The more realistic example has the following SCCs: {t0}	{t1, t2}	{F1, F2, F3}	{F4}
		{name: "more-realistic", graph: suite["more-realistic"], want: []string{"Local(t0)", "Local(t1);Local(t2)", "Function(F1);Function(F2);Function(F3)", "Function(F4)"}},
	} {
		sccs, idxToSccID := scc(test.graph)
		if got := sccString(sccs, test.graph); !sccEqual(test.want, got) {
			t.Errorf("want %v for graph %v; got %v", test.want, test.name, got)
		}
		if !isRevTopSorted(test.graph, idxToSccID) {
			t.Errorf("%v not topologically sorted", test.name)
		}
		if !sccMapsConsistent(sccs, idxToSccID) {
			t.Errorf("%v: scc maps not consistent", test.name)
		}
		break
	}
}

func TestPropagation(t *testing.T) {
	suite := testSuite(t)
	var canon typeutil.Map
	for _, test := range []struct {
		name  string
		graph *vtaGraph
		want  map[string]string
	}{
		// No cycles graph pushes type information forward.
		{name: "no-cycles", graph: suite["no-cycles"],
			want: map[string]string{
				"Local(t0)": "A",
				"Local(t1)": "A;B",
				"Local(t2)": "A;B;C",
			},
		},
		// No interesting type flow in trivial cycle graph.
		{name: "trivial-cycle", graph: suite["trivial-cycle"],
			want: map[string]string{
				"Local(t0)": "A",
				"Local(t1)": "B",
			},
		},
		// Circle cycle makes type A and B get propagated everywhere.
		{name: "circle-cycle", graph: suite["circle-cycle"],
			want: map[string]string{
				"Local(t0)": "A;B",
				"Local(t1)": "A;B",
				"Local(t2)": "A;B",
			},
		},
		// Similarly for fully connected graph.
		{name: "fully-connected", graph: suite["fully-connected"],
			want: map[string]string{
				"Local(t0)": "A;B;C",
				"Local(t1)": "A;B;C",
				"Local(t2)": "A;B;C",
			},
		},
		// The outer loop of subsumed-scc pushes A and B through the graph.
		{name: "subsumed-scc", graph: suite["subsumed-scc"],
			want: map[string]string{
				"Local(t0)": "A;B",
				"Local(t1)": "A;B",
				"Local(t2)": "A;B",
				"Local(t3)": "A;B",
			},
		},
		// More realistic graph has a more fine grained flow.
		{name: "more-realistic", graph: suite["more-realistic"],
			want: map[string]string{
				"Local(t0)":    "A",
				"Local(t1)":    "A;B",
				"Local(t2)":    "A;B",
				"Function(F1)": "A;B;F1;F2;F3",
				"Function(F2)": "A;B;F1;F2;F3",
				"Function(F3)": "A;B;F1;F2;F3",
				"Function(F4)": "A;B;F1;F2;F3;F4",
			},
		},
	} {
		if got := nodeToTypeString(propagate(test.graph, &canon)); !reflect.DeepEqual(got, test.want) {
			t.Errorf("want %v for graph %v; got %v", test.want, test.name, got)
		}
	}
}

func testLastIndex[S ~[]E, E comparable](t *testing.T, s S, e E, want int) {
	if got := slicesLastIndex(s, e); got != want {
		t.Errorf("LastIndex(%v, %v): got %v want %v", s, e, got, want)
	}
}

func TestLastIndex(t *testing.T) {
	testLastIndex(t, []int{10, 20, 30}, 10, 0)
	testLastIndex(t, []int{10, 20, 30}, 20, 1)
	testLastIndex(t, []int{10, 20, 30}, 30, 2)
	testLastIndex(t, []int{10, 20, 30}, 42, -1)
	testLastIndex(t, []int{10, 20, 10}, 10, 2)
	testLastIndex(t, []int{20, 10, 10}, 10, 2)
	testLastIndex(t, []int{10, 10, 20}, 10, 1)
	type foo struct {
		i int
		s string
	}
	testLastIndex(t, []foo{{1, "abc"}, {2, "abc"}, {1, "xyz"}}, foo{1, "abc"}, 0)
	// Test that LastIndex doesn't use bitwise comparisons for floats.
	neg0 := 1 / math.Inf(-1)
	nan := math.NaN()
	testLastIndex(t, []float64{0, neg0}, 0, 1)
	testLastIndex(t, []float64{0, neg0}, neg0, 1)
	testLastIndex(t, []float64{neg0, 0}, 0, 1)
	testLastIndex(t, []float64{neg0, 0}, neg0, 1)
	testLastIndex(t, []float64{0, nan}, 0, 0)
	testLastIndex(t, []float64{0, nan}, nan, -1)
	testLastIndex(t, []float64{0, nan}, 1, -1)
}


================================================
FILE: go/callgraph/vta/testdata/src/arrays_generics.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type F func()

func set[T [1]F | [2]F](arr *T, i int) {
	// Indexes into a pointer to an indexable type T and T does not have a coretype.
	// SSA instruction:	t0 = &arr[i]
	(*arr)[i] = bar
}

func bar() {
	print("here")
}

func Foo() {
	var arr [1]F
	set(&arr, 0)
	arr[0]()
}

// WANT:
// Foo: set[[1]testdata.F](t0, 0:int) -> set[[1]testdata.F]; t3() -> bar


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_collections.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

func Do(a A, b B) map[I]I {
	m := make(map[I]I)
	m[a] = B{}
	m[b] = b
	return m
}

func Baz(a A, b B) {
	var x []I
	for k, v := range Do(a, b) {
		k.Foo()
		v.Foo()

		x = append(x, k)
	}

	x[len(x)-1].Foo()
}

// WANT:
// Baz: Do(a, b) -> Do; invoke t16.Foo() -> A.Foo, B.Foo; invoke t5.Foo() -> A.Foo, B.Foo; invoke t6.Foo() -> B.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_comma_maps.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Name() string
	Foo()
}

var is = make(map[string]I)

func init() {
	register(A{})
	register(B{})
}

func register(i I) {
	is[i.Name()] = i
}

type A struct{}

func (a A) Foo()         {}
func (a A) Name() string { return "a" }

type B struct{}

func (b B) Foo()         {}
func (b B) Name() string { return "b" }

func Do(n string) {
	i, ok := is[n]
	if !ok {
		return
	}
	i.Foo()
}

func Go(n string) {
	if i, ok := is[n]; !ok {
		return
	} else {
		i.Foo()
	}
}

func To(n string) {
	var i I
	var ok bool

	if i, ok = is[n]; !ok {
		return
	}
	i.Foo()
}

func Ro(n string) {
	i := is[n]
	i.Foo()
}

// Relevant SSA:
// func Do(n string):
//        t0 = *is
//        t1 = t0[n],ok
//        t2 = extract t1 #0
//        t3 = extract t1 #1
//        if t3 goto 2 else 1
// 1:
//        return
// 2:
//        t4 = invoke t2.Foo()
//        return

// WANT:
// register: invoke i.Name() -> A.Name, B.Name
// Do: invoke t2.Foo() -> A.Foo, B.Foo
// Go: invoke t2.Foo() -> A.Foo, B.Foo
// To: invoke t2.Foo() -> A.Foo, B.Foo
// Ro: invoke t1.Foo() -> A.Foo, B.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_field_funcs.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type WrappedFunc struct {
	F func() complex64
}

func callWrappedFunc(f WrappedFunc) {
	f.F()
}

func foo() complex64 {
	println("foo")
	return -1
}

func Foo(b bool) {
	callWrappedFunc(WrappedFunc{foo})
	x := func() {}
	y := func() {}
	var a *func()
	if b {
		a = &x
	} else {
		a = &y
	}
	(*a)()
}

// Relevant SSA:
// func Foo(b bool):
//         t0 = local WrappedFunc (complit)
//         t1 = &t0.F [#0]
//         *t1 = foo
//         t2 = *t0
//         t3 = callWrappedFunc(t2)
//         t4 = new func() (x)
//         *t4 = Foo$1
//         t5 = new func() (y)
//         *t5 = Foo$2
//         if b goto 1 else 3
// 1:
//         jump 2
// 2:
//         t6 = phi [1: t4, 3: t5] #a
//         t7 = *t6
//         t8 = t7()
//         return
// 3:
//         jump 2
//
// func callWrappedFunc(f WrappedFunc):
//         t0 = local WrappedFunc (f)
//         *t0 = f
//         t1 = &t0.F [#0]
//         t2 = *t1
//         t3 = t2()
//         return

// WANT:
// callWrappedFunc: t2() -> foo
// Foo: callWrappedFunc(t2) -> callWrappedFunc; t7() -> Foo$1, Foo$2


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_fields.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct {
	I
}

func (a *A) Do() {
	a.Foo()
}

type B struct{}

func (b B) Foo() {}

func NewA(b B) *A {
	return &A{I: &b}
}

func Baz(b B) {
	a := NewA(b)
	a.Do()
}

// WANT:
// Baz: (*A).Do(t0) -> A.Do; NewA(b) -> NewA
// A.Do: invoke t1.Foo() -> B.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_generics.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

func instantiated[X any](x *X) int {
	print(x)
	return 0
}

type I interface {
	Bar()
}

func interfaceInstantiated[X I](x X) {
	x.Bar()
}

type A struct{}

func (a A) Bar() {}

type B struct{}

func (b B) Bar() {}

func Foo(a A, b B) {
	x := true
	instantiated[bool](&x)
	y := 1
	instantiated[int](&y)

	interfaceInstantiated[A](a)
	interfaceInstantiated[B](b)
}

// Relevant SSA:
//func Foo(a A, b B):
//  t0 = new bool (x)
//  *t0 = true:bool
//  t1 = instantiated[bool](t2)
//  t1 = new int (y)
//  *t2 = 1:int
//  t3 = instantiated[[int]](t4)
//  t4 = interfaceInstantiated[testdata.A](a)
//  t5 = interfaceInstantiated[testdata.B](b)
//  return
//
//func interfaceInstantiated[[testdata.B]](x B):
//  t0 = (B).Bar(b)
//  return
//
//func interfaceInstantiated[X I](x X):
//        (external)

// WANT:
// Foo: instantiated[bool](t0) -> instantiated[bool]; instantiated[int](t2) -> instantiated[int]; interfaceInstantiated[testdata.A](a) -> interfaceInstantiated[testdata.A]; interfaceInstantiated[testdata.B](b) -> interfaceInstantiated[testdata.B]
// interfaceInstantiated[testdata.B]: (B).Bar(x) -> B.Bar
// interfaceInstantiated[testdata.A]: (A).Bar(x) -> A.Bar


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_ho.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

func Foo() {}

func Do(b bool) func() {
	if b {
		return Foo
	}
	return func() {}
}

func Finish(h func()) {
	h()
}

func Baz(b bool) {
	Finish(Do(b))
}

// Relevant SSA:
// func Baz(b bool):
//   t0 = Do(b)
//   t1 = Finish(t0)
//   return

// func Do(b bool) func():
//   if b goto 1 else 2
//  1:
//   return Foo
//  2:
//   return Do$1

// func Finish(h func()):
//   t0 = h()
//   return

// WANT:
// Baz: Do(b) -> Do; Finish(t0) -> Finish
// Finish: h() -> Do$1, Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_interfaces.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

type C struct{}

func (c C) Foo() {}

func NewB() B {
	return B{}
}

func Do(b bool) I {
	if b {
		return A{}
	}

	c := C{}
	c.Foo()

	return NewB()
}

func Baz(b bool) {
	Do(b).Foo()
}

// Relevant SSA:
// func Baz(b bool):
//   t0 = Do(b)
//   t1 = invoke t0.Foo()
//   return

// func Do(b bool) I:
//    ...
//   t1 = (C).Foo(C{}:C)
//   t2 = NewB()
//   t3 = make I <- B (t2)
//   return t3

// WANT:
// Baz: Do(b) -> Do; invoke t0.Foo() -> A.Foo, B.Foo
// Do: (C).Foo(C{}:C) -> C.Foo; NewB() -> NewB


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_issue_57756.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

// Test that the values of a named function type are correctly
// flowing from interface objects i in i.Foo() to the receiver
// parameters of callees of i.Foo().

type H func()

func (h H) Do() {
	h()
}

type I interface {
	Do()
}

func Bar() I {
	return H(func() {})
}

func For(g G) {
	b := Bar()
	b.Do()

	g[0] = b
	g.Goo()
}

type G []I

func (g G) Goo() {
	g[0].Do()
}

// Relevant SSA:
// func Bar$1():
//   return
//
// func Bar() I:
//   t0 = changetype H <- func() (Bar$1)
//   t1 = make I <- H (t0)
//
// func For():
//   t0 = Bar()
//   t1 = invoke t0.Do()
//   t2 = &g[0:int]
//   *t2 = t0
//   t3 = (G).Goo(g)
//
// func (h H) Do():
//   t0 = h()
//
// func (g G) Goo():
//   t0 = &g[0:int]
//   t1 = *t0
//   t2 = invoke t1.Do()

// WANT:
// For: (G).Goo(g) -> G.Goo; Bar() -> Bar; invoke t0.Do() -> H.Do
// H.Do: h() -> Bar$1
// G.Goo: invoke t1.Do() -> H.Do


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_nested_ptr.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

func Do(i **I) {
	**i = A{}
}

func Bar(i **I) {
	**i = B{}
}

func Baz(i **I) {
	Do(i)
	(**i).Foo()
}

// Relevant SSA:
//  func Baz(i **I):
//   t0 = Do(i)
//   t1 = *i
//   t2 = *t1
//   t3 = invoke t2.Foo()
//   return

//  func Bar(i **I):
//   t0 = *i
//   t1 = local B (complit)
//   t2 = *t1
//   t3 = make I <- B (t2)
//   *t0 = t3
//   return

// func Do(i **I):
//   t0 = *i
//   t1 = local A (complit)
//   t2 = *t1
//   t3 = make I <- A (t2)
//   *t0 = t3
//   return

// WANT:
// Baz: Do(i) -> Do; invoke t2.Foo() -> A.Foo, B.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_pointers.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct {
	f *I
}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

func Do(a A, i I, c bool) *I {
	if c {
		*a.f = a
	} else {
		a.f = &i
	}
	(*a.f).Foo()
	return &i
}

func Baz(a A, b B, c bool) {
	x := Do(a, b, c)
	(*x).Foo()
}

// The command a.f = &i introduces aliasing that results in
// A and B reaching both *A.f and return value of Do(a, b, c).

// WANT:
// Baz: Do(a, t0, c) -> Do; invoke t2.Foo() -> A.Foo, B.Foo
// Do: invoke t8.Foo() -> A.Foo, B.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_range_over_func.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

type C struct{}

func (c C) Foo() {} // Test that this is not called.

type iset []I

func (i iset) All() func(func(I) bool) {
	return func(yield func(I) bool) {
		for _, v := range i {
			if !yield(v) {
				return
			}
		}
	}
}

var x = iset([]I{A{}, B{}})

func X() {
	for i := range x.All() {
		i.Foo()
	}
}

func Y() I {
	for i := range x.All() {
		return i
	}
	return nil
}

func Bar() {
	X()
	y := Y()
	y.Foo()
}

// Relevant SSA:
//func X$1(I) bool:
//	t0 = *jump$1
//	t1 = t0 == 0:int
//	if t1 goto 1 else 2
//1:
//	*jump$1 = -1:int
//	t2 = invoke arg0.Foo()
//	*jump$1 = 0:int
//	return true:bool
//2:
//	t3 = make interface{} <- string ("yield function ca...":string) interface{}
//	panic t3
//
//func All$1(yield func(I) bool):
//	t0 = *i
//	t1 = len(t0)
//	jump 1
//1:
//	t2 = phi [0: -1:int, 2: t3] #rangeindex
//	t3 = t2 + 1:int
//	t4 = t3 < t1
//	if t4 goto 2 else 3
//2:
//	t5 = &t0[t3]
//	t6 = *t5
//	t7 = yield(t6)
//	if t7 goto 1 else 4
//
//func Bar():
//	t0 = X()
//	t1 = Y()
//	t2 = invoke t1.Foo()
//	return

// WANT:
// Bar: X() -> X; Y() -> Y; invoke t1.Foo() -> A.Foo, B.Foo
// X$1: invoke arg0.Foo() -> A.Foo, B.Foo
// All$1: yield(t6) -> X$1, Y$1


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_recursive_types.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo() I
}

type A struct {
	i int
	a *A
}

func (a *A) Foo() I {
	return a
}

type B **B

type C *D
type D *C

func Bar(a *A, b *B, c *C, d *D) {
	Baz(a)
	Baz(a.a)

	sink(*b)
	sink(*c)
	sink(*d)
}

func Baz(i I) {
	i.Foo()
}

func sink(i interface{}) {
	print(i)
}

// Relevant SSA:
// func Baz(i I):
//   t0 = invoke i.Foo()
//   return
//
// func Bar(a *A, b *B):
//   t0 = make I <- *A (a)
//   t1 = Baz(t0)
//   ...

// WANT:
// Bar: Baz(t0) -> Baz; Baz(t4) -> Baz; sink(t10) -> sink; sink(t13) -> sink; sink(t7) -> sink
// Baz: invoke i.Foo() -> A.Foo


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_static.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type A struct{}

func (a A) foo() {}

func Bar() {}

func Baz(a A) {
	a.foo()
	Bar()
	Baz(A{})
}

// Relevant SSA:
// func Baz(a A):
//   t0 = (A).foo(a)
//   t1 = Bar()
//   t2 = Baz(A{}:A)

// WANT:
// Baz: (A).foo(a) -> A.foo; Bar() -> Bar; Baz(A{}:A) -> Baz


================================================
FILE: go/callgraph/vta/testdata/src/callgraph_type_aliases.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

// This file is the same as callgraph_interfaces.go except for
// types J, X, Y, and Z aliasing types I, A, B, and C, resp.

package testdata

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

type B struct{}

func (b B) Foo() {}

type C struct{}

func (c C) Foo() {}

type J = I
type X = A
type Y = B
type Z = C

func NewY() Y {
	return Y{}
}

func Do(b bool) J {
	if b {
		return X{}
	}

	z := Z{}
	z.Foo()

	return NewY()
}

func Baz(b bool) {
	Do(b).Foo()
}

// Relevant SSA:
// func Baz(b bool):
//   t0 = Do(b)
//   t1 = invoke t0.Foo()
//   return

// func Do(b bool) I:
//    ...
//   t1 = (C).Foo(Z{}:Z)
//   t2 = NewY()
//   t3 = make I <- B (t2)
//   return t3

// WANT:
// Baz: Do(b) -> Do; invoke t0.Foo() -> A.Foo, B.Foo
// Do: (C).Foo(Z{}:Z) -> C.Foo; NewY() -> NewY


================================================
FILE: go/callgraph/vta/testdata/src/channels.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

func foo(c chan interface{}, j int) {
	c <- j + 1
}

func Baz(i int) {
	c := make(chan interface{})
	go foo(c, i)
	x := <-c
	print(x)
}

// Relevant SSA:
//  func foo(c chan interface{}, j int):
//  t0 = j + 1:int
//  t1 = make interface{} <- int (t0)
//  send c <- t1                        // t1 -> chan {}interface
//  return
//
// func Baz(i int):
//  t0 = make chan interface{} 0:int
//  go foo(t0, i)
//  t1 = <-t0                           // chan {}interface -> t1
//  t2 = print(t1)
//  return

// WANT:
// Channel(chan interface{}) -> Local(t1)
// Local(t1) -> Channel(chan interface{})


================================================
FILE: go/callgraph/vta/testdata/src/closures.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

func Do(i I) { i.Foo() }

func Baz(b bool, h func(I)) {
	var i I
	a := func(g func(I)) {
		g(i)
	}

	if b {
		h = Do
	}

	a(h)
}

// Relevant SSA:
//  func Baz(b bool, h func(I)):
//    t0 = new I (i)
//    t1 = make closure Baz$1 [t0]
//    if b goto 1 else 2
//   1:
//         jump 2
//   2:
//    t2 = phi [0: h, 1: Do] #h
//    t3 = t1(t2)
//    return
//
// func Baz$1(g func(I)):
//    t0 = *i
//    t1 = g(t0)
//    return

// In the edge set Local(i) -> Local(t0), Local(t0) below,
// two occurrences of t0 come from t0 in Baz and Baz$1.

// WANT:
// Function(Do) -> Local(t2)
// Function(Baz$1) -> Local(t1)
// Local(h) -> Local(t2)
// Local(t0) -> Local(i)
// Local(i) -> Local(t0), Local(t0)


================================================
FILE: go/callgraph/vta/testdata/src/d/d.go
================================================
package d

func D(i int) int {
	return i + 1
}

type Data struct {
	V int
}

func (d Data) Do() int {
	return d.V - 1
}


================================================
FILE: go/callgraph/vta/testdata/src/dynamic_calls.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	foo(I)
}

type A struct{}

func (a A) foo(ai I) {}

type B struct{}

func (b B) foo(bi I) {}

func doWork() I { return nil }
func close() I  { return nil }

func Baz(x B, h func() I, i I) I {
	i.foo(x)

	return h()
}

var g *B = &B{} // ensure *B.foo is created.

// Relevant SSA:
// func Baz(x B, h func() I, i I) I:
//   t0 = make I <- B (x)
//   t1 = invoke i.foo(t0)
//   t2 = h()
//   return t2

// Local(t0) has seemingly duplicates of successors. This
// happens in stringification of type propagation graph.
// Due to CHA, we analyze A.foo and *A.foo as well as B.foo
// and *B.foo, which have similar bodies and hence similar
// type flow that gets merged together during stringification.

// WANT:
// Return(doWork[0]) -> Local(t2)
// Return(close[0]) -> Local(t2)
// Local(t0) -> Local(ai), Local(ai), Local(bi), Local(bi)
// Constant(testdata.I) -> Return(close[0]), Return(doWork[0])
// Local(x) -> Local(t0)


================================================
FILE: go/callgraph/vta/testdata/src/fields.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type J interface {
	I
	Bar()
}

type A struct{}

func (a A) Foo() {}
func (a A) Bar() {}

type B struct {
	a A
	i I
}

func Do() B {
	b := B{}
	return b
}

func Baz(b B) {
	var j J
	j = b.a

	j.Bar()

	b.i = j

	Do().i.Foo()
}

// Relevant SSA:
// func Baz(b B):
//   t0 = local B (b)
//   *t0 = b
//   t1 = &t0.a [#0]       // no flow here since a is of concrete type
//   t2 = *t1
//   t3 = make J <- A (t2)
//   t4 = invoke t3.Bar()
//   t5 = &t0.i [#1]
//   t6 = change interface I <- J (t3)
//   *t5 = t6
//   t7 = Do()
//   t8 = t7.i [#0]
//   t9 = (A).Foo(t8)
//   return

// WANT:
// Field(testdata.B:i) -> Local(t5), Local(t8)
// Local(t5) -> Field(testdata.B:i)
// Local(t2) -> Local(t3)
// Local(t3) -> Local(t6)
// Local(t6) -> Local(t5)


================================================
FILE: go/callgraph/vta/testdata/src/function_alias.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type Doer func()

type A struct {
	foo func()
	do  Doer
}

func Baz(f func()) {
	j := &f
	k := &j
	**k = func() {}
	a := A{}
	a.foo = **k
	a.foo()
	a.do = a.foo
	a.do()
}

// Relevant SSA:
// func Baz(f func()):
//        t0 = new func() (f)
//        *t0 = f
//        t1 = new *func() (j)
//        *t1 = t0
//        t2 = *t1
//        *t2 = Baz$1
//        t3 = local A (a)
//        t4 = *t1
//        t5 = *t4
//        t6 = &t3.foo [#0]
//        *t6 = t5
//        t7 = &t3.foo [#0]
//        t8 = *t7
//        t9 = t8()
//        t10 = &t3.foo [#0]                                              *func()
//        t11 = *t10                                                       func()
//        t12 = &t3.do [#1]                                                 *Doer
//        t13 = changetype Doer <- func() (t11)                              Doer
//        *t12 = t13
//        t14 = &t3.do [#1]                                                 *Doer
//        t15 = *t14                                                         Doer
//        t16 = t15()                                                          ()

// Flow chain showing that Baz$1 reaches t8():
//   Baz$1 -> t2 <-> PtrFunction(func()) <-> t4 -> t5 -> t6 <-> Field(testdata.A:foo) <-> t7 -> t8
// Flow chain showing that Baz$1 reaches t15():
//  Field(testdata.A:foo) <-> t10 -> t11 -> t13 -> t12 <-> Field(testdata.A:do) <-> t14 -> t15

// WANT:
// Local(f) -> Local(t0)
// Local(t0) -> PtrFunction(func())
// Function(Baz$1) -> Local(t2)
// PtrFunction(func()) -> Local(t0), Local(t2), Local(t4)
// Local(t2) -> PtrFunction(func())
// Local(t6) -> Field(testdata.A:foo)
// Local(t4) -> Local(t5), PtrFunction(func())
// Local(t5) -> Local(t6)
// Local(t7) -> Field(testdata.A:foo), Local(t8)
// Field(testdata.A:foo) -> Local(t10), Local(t6), Local(t7)
// Local(t6) -> Field(testdata.A:foo)
// Field(testdata.A:do) -> Local(t12), Local(t14)
// Local(t12) -> Field(testdata.A:do)
// Local(t10) -> Field(testdata.A:foo), Local(t11)
// Local(t11) -> Local(t13)
// Local(t13) -> Local(t12)
// Local(t14) -> Field(testdata.A:do), Local(t15)


================================================
FILE: go/callgraph/vta/testdata/src/generic_channels.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I1 interface{}
type I2 interface{}
type I3 interface{}

func Foo[C interface{ ~chan I1 | ~chan<- I1 }](c C, j int) {
	c <- j
}

func Bar[C interface{ ~chan I2 | ~<-chan I2 }](c C) {
	x := <-c
	print(x)
}

func Baz[C interface{ ~chan I3 | ~<-chan I3 }](c C) {
	select {
	case x := <-c:
		print(x)
	default:
	}
}

// WANT:
// Local(t0) -> Channel(chan testdata.I1)
// Channel(chan testdata.I2) -> Local(t0)
// Channel(chan testdata.I3) -> Local(t0[2])


================================================
FILE: go/callgraph/vta/testdata/src/go117.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type J interface {
	Foo()
	Bar()
}

type B struct {
	p int
}

func (b B) Foo() {}
func (b B) Bar() {}

func Wobble(b *B, s []J) {
	x := (*[3]J)(s)
	x[1] = b

	a := &s[2]
	(*a).Bar()
}

// Relevant SSA:
// func Wobble(b *B, s []J):
//   t0 = slice to array pointer *[3]J <- []J (s)                      *[3]J
//   t1 = &t0[1:int]                                                      *J
//   t2 = make J <- *B (b)                                                 J
//   *t1 = t2
//   t3 = &s[2:int]                                                       *J
//   ...

// WANT:
// Local(t1) -> Slice([]testdata.J)
// Slice([]testdata.J) -> Local(t1), Local(t3)


================================================
FILE: go/callgraph/vta/testdata/src/issue63146.go
================================================
package test

type embedded struct{}

type S struct{ embedded }

func (_ S) M() {}

type C interface {
	M()
	S
}

func G[T C]() {
	t := T{embedded{}}
	t.M()
}

func F() {
	G[S]()
}

// WANT:
// F: G[testdata.S]() -> G[testdata.S]
// G[testdata.S]: (S).M(t2) -> S.M
// S.M: (testdata.S).M(t1) -> S.M


================================================
FILE: go/callgraph/vta/testdata/src/maps.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo() string
}

type J interface {
	Foo() string
	Bar()
}

type B struct {
	p string
}

func (b B) Foo() string { return b.p }
func (b B) Bar()        {}

func Baz(m map[I]I, b1, b2 B, n map[string]*J) *J {
	m[b1] = b2

	return n[b1.Foo()]
}

// Relevant SSA:
// func Baz(m map[I]I, b1 B, b2 B, n map[string]*J) *J:
//   t0 = make I <- B (b1)
//   t1 = make I <- B (b2)
//   m[t0] = t1
//   t2 = (B).Foo(b1)
//   t3 = n[t2]
//   return t3

// WANT:
// Local(b2) -> Local(t1)
// Local(t1) -> MapValue(testdata.I)
// Local(t0) -> MapKey(testdata.I)
// Local(t3) -> MapValue(*testdata.J), Return(Baz[0])
// MapValue(*testdata.J) -> Local(t3)


================================================
FILE: go/callgraph/vta/testdata/src/node_uniqueness.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

// TestNodeTypeUniqueness checks if semantically equivalent types
// are being represented using the same pointer value in vta nodes.
// If not, some edges become missing in the string representation
// of the graph.

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {}

func Baz(a *A) (I, I, interface{}, interface{}) {
	var i I
	i = a

	var ii I
	aa := &A{}
	ii = aa

	m := make(map[int]int)
	var iii interface{}
	iii = m

	var iiii interface{}
	iiii = m

	return i, ii, iii, iiii
}

// Relevant SSA:
// func Baz(a *A) (I, I, interface{}, interface{}):
//   t0 = make I <- *A (a)
//	 t1 = new A (complit)
//   t2 = make I <- *A (t1)
//   t3 = make map[int]int
//   t4 = make interface{} <- map[int]int (t3)
//   t5 = make interface{} <- map[int]int (t3)
//   return t0, t2, t4, t5

// Without canon approach, one of Pointer(*A) -> Local(t0) and Pointer(*A) -> Local(t2) edges is
// missing in the graph string representation. The original graph has both of the edges but the
// source node Pointer(*A) is not the same; two occurrences of Pointer(*A) are considered separate
// nodes. Since they have the same string representation, one edge gets overridden by the other
// during the graph stringification, instead of being joined together as in below.

// WANT:
// Pointer(*testdata.A) -> Local(t0), Local(t2)
// Local(t3) -> Local(t4), Local(t5)


================================================
FILE: go/callgraph/vta/testdata/src/panic.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	foo()
}

type A struct{}

func (a A) foo() {}

func recover1() {
	print("only this recover should execute")
	if r, ok := recover().(I); ok {
		r.foo()
	}
}

func recover2() {
	recover()
}

func Baz(a A) {
	defer recover1()
	defer recover()
	panic(a)
}

// Relevant SSA:
// func recover1():
//   t0 = print("only this recover...":string)
//   t1 = recover()
//   t2 = typeassert,ok t1.(I)
//   t3 = extract t2 #0
//   t4 = extract t2 #1
//   if t4 goto 1 else 2
//  1:
//   t5 = invoke t3.foo()
//   jump 2
//  2:
//   return
//
// func recover2():
//   t0 = recover()
//   return
//
// func Baz(i I):
//   defer recover1()
//   t0 = make interface{} <- A (a)
//   panic t2

// t0 argument to panic in Baz gets ultimately connected to recover
// registers t1 in recover1() and t0 in recover2().

// WANT:
// Panic -> Recover
// Local(t0) -> Panic
// Recover -> Local(t0), Local(t1)


================================================
FILE: go/callgraph/vta/testdata/src/phi.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type A struct{}
type B struct{}

type I interface{ foo() }

func (a A) foo() {}
func (b B) foo() {}

func Baz(b B, c bool) {
	var i I
	if c {
		i = b
	} else {
		a := A{}
		i = a
	}
	i.foo()
}

// Relevant SSA:
// func Baz(b B, c bool):
// 0:
//  if c goto 1 else 3
//
// 1:
//  t0 = make I <- B (b)
//  jump 2
//
// 2:
//  t1 = phi [1: t0, 3: t3] #i
//  t2 = invoke t1.foo()
//  return
//
// 3:
//  t3 = make I <- A (struct{}{}:A)
//  jump 2

// WANT:
// Local(b) -> Local(t0)
// Local(t0) -> Local(t1)
// Local(t3) -> Local(t1)
// Constant(testdata.A) -> Local(t3)


================================================
FILE: go/callgraph/vta/testdata/src/phi_alias.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type B struct {
	p int
}

func (b B) Foo() {}

func Baz(i, j *I, b, c bool) {
	if b {
		i = j
	}
	*i = B{9}
	if c {
		(*i).Foo()
	} else {
		(*j).Foo()
	}
}

// Relevant SSA:
// func Baz(i *I, j *I, b bool, c bool):
//    if b goto 1 else 2
//  1:
//    jump 2
//  2:
//    t0 = phi [0: i, 1: j] #i
//    t1 = local B (complit)
//    t2 = &t1.p [#0]
//    *t2 = 9:int
//    t3 = *t1
//    t4 = make I <- B (t3)
//    *t0 = t4
//    if c goto 3 else 5
//  3:
//    t5 = *t0
//    t6 = invoke t5.Foo()
//    jump 4
//  4:
//    return
//  5:
//    t7 = *j
//    t8 = invoke t7.Foo()
//    jump 4

// Flow chain showing that B reaches (*i).foo():
//   t3 (B) -> t4 -> t0 -> t5
// Flow chain showing that B reaches (*j).foo():
//   t3 (B) -> t4 -> t0 <--> j -> t7

// WANT:
// Local(t0) -> Local(i), Local(j), Local(t5)
// Local(i) -> Local(t0)
// Local(j) -> Local(t0), Local(t7)
// Local(t3) -> Local(t4)
// Local(t4) -> Local(t0)


================================================
FILE: go/callgraph/vta/testdata/src/ranges.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo() string
}

type B struct {
	p string
}

func (b B) Foo() string { return b.p }

func Baz(m map[I]*I) {
	for i, v := range m {
		*v = B{p: i.Foo()}
	}
}

// Relevant SSA:
//  func Baz(m map[I]*I):
//   0:
//    t0 = range m
//         jump 1
//   1:
//    t1 = next t0
//    t2 = extract t1 #0
//    if t2 goto 2 else 3
//   2:
//    t3 = extract t1 #1
//    t4 = extract t1 #2
//    t5 = local B (complit)
//    t6 = &t5.p [#0]
//    t7 = invoke t3.Foo()
//    *t6 = t7
//    t8 = *t5
//    t9 = make I <- B (t8)
//    *t4 = t9
//    jump 1
//   3:
//    return

// WANT:
// MapKey(testdata.I) -> Local(t1[1])
// Local(t1[1]) -> Local(t3)
// MapValue(*testdata.I) -> Local(t1[2])
// Local(t1[2]) -> Local(t4), MapValue(*testdata.I)
// Local(t8) -> Local(t9)
// Local(t9) -> Local(t4)
// Local(t4) -> Local(t1[2])


================================================
FILE: go/callgraph/vta/testdata/src/returns.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface{}

func Bar(ii I) (I, I) {
	return Foo(ii)
}

func Foo(iii I) (I, I) {
	return iii, iii
}

func Do(j I) *I {
	return &j
}

func Baz(i I) *I {
	Bar(i)
	return Do(i)
}

// Relevant SSA:
// func Bar(ii I) (I, I):
//   t0 = Foo(ii)
//   t1 = extract t0 #0
//   t2 = extract t0 #1
//   return t1, t2
//
// func Foo(iii I) (I, I):
//   return iii, iii
//
// func Do(j I) *I:
//   t0 = new I (j)
//   *t0 = j
//   return t0
//
// func Baz(i I):
//   t0 = Bar(i)
//   t1 = Do(i)
//   return t1

// t0 and t1 in the last edge correspond to the nodes
// of Do and Baz. This edge is induced by Do(i).

// WANT:
// Local(i) -> Local(ii), Local(j)
// Local(ii) -> Local(iii)
// Local(iii) -> Return(Foo[0]), Return(Foo[1])
// Local(t1) -> Return(Baz[0])
// Local(t1) -> Return(Bar[0])
// Local(t2) -> Return(Bar[1])
// Local(t0) -> Return(Do[0])
// Return(Do[0]) -> Local(t1)


================================================
FILE: go/callgraph/vta/testdata/src/select.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo() string
}

type J interface {
	I
}

type B struct {
	p string
}

func (b B) Foo() string { return b.p }

func Baz(b1, b2 B, c1 chan I, c2 chan J) {
	for {
		select {
		case c1 <- b1:
			print("b1")
		case c2 <- b2:
			print("b2")
		case <-c1:
			print("c1")
		case k := <-c2:
			print(k.Foo())
			return
		}
	}
}

// Relevant SSA:
// func Baz(b1 B, b2 B, c1 chan I, c2 chan J):
//   ...
//   t0 = make I <- B (b1)
//   t1 = make J <- B (b2)
//   t2 = select blocking [c1<-t0, c2<-t1, <-c1, <-c2] (index int, ok bool, I, J)
//   t3 = extract t2 #0
//   t4 = t73== 0:int
//   if t4 goto 2 else 3
//         ...
//  8:
//   t12 = extract t2 #3
//   t13 = invoke t12.Foo()
//   t14 = print(t15)

// WANT:
// Local(t0) -> Channel(chan testdata.I)
// Local(t1) -> Channel(chan testdata.J)
// Channel(chan testdata.I) -> Local(t2[2])
// Channel(chan testdata.J) -> Local(t2[3])


================================================
FILE: go/callgraph/vta/testdata/src/simple.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

var gl int

type X struct {
	a int
	b int
}

func main() {
	print(gl)
}

func foo() (r int) { return gl }


================================================
FILE: go/callgraph/vta/testdata/src/static_calls.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface{}

func foo(i I) (I, I) {
	return i, i
}

func doWork(ii I) {}

func close(iii I) {}

func Baz(inp I) {
	a, b := foo(inp)
	defer close(a)
	go doWork(b)
}

// Relevant SSA:
// func Baz(inp I):
//   t0 = foo(inp)
//   t1 = extract t0 #0
//   t2 = extract t0 #1
//   defer close(t1)
//   go doWork(t2)
//   rundefers
//   ...
// func foo(i I) (I, I):
//   return i, i

// WANT:
// Local(inp) -> Local(i)
// Local(t1) -> Local(iii)
// Local(t2) -> Local(ii)
// Local(i) -> Return(foo[0]), Return(foo[1])
// Return(foo[0]) -> Local(t0[0])
// Return(foo[1]) -> Local(t0[1])


================================================
FILE: go/callgraph/vta/testdata/src/store.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

// Tests graph creation for store/load and make instructions.
// Note that ssa package does not have a load instruction per
// se. Yet, one is encoded as a unary instruction with the
// * operator.

type A struct{}

type I interface{ foo() }

func (a A) foo() {}

func main() {
	a := A{}
	var i I
	i = a
	ii := &i
	(*ii).foo()
}

// Relevant SSA:
//	t0 = new I (i)
//	t1 = make I <- A (struct{}{}:A)    A  -> t1
//	*t0 = t1                           t1 -> t0
//	t2 = *t0                           t0 -> t2
//	t3 = invoke t2.foo()
//	return

// WANT:
// Constant(testdata.A) -> Local(t1)
// Local(t1) -> Local(t0)
// Local(t0) -> Local(t2)


================================================
FILE: go/callgraph/vta/testdata/src/store_load_alias.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type A struct{}

func (a A) foo() {}

type I interface{ foo() }

func Baz(i I) {
	j := &i
	k := &j
	**k = A{}
	i.foo()
	(**k).foo()
}

// Relevant SSA:
// func Baz(i I):
//   t0 = new I (i)
//   *t0 = i
//   t1 = new *I (j)
//   *t1 = t0
//   t2 = *t1
// 	 t3 = make I <- A (struct{}{}:A)                                       I
//   *t2 = t3
//   t4 = *t0
//   t5 = invoke t4.foo()
//   t6 = *t1
//   t7 = *t6
//   t8 = invoke t7.foo()

// Flow chain showing that A reaches i.foo():
//   Constant(A) -> t3 -> t2 <-> PtrInterface(I) <-> t0 -> t4
// Flow chain showing that A reaches (**k).foo():
//	 Constant(A) -> t3 -> t2 <-> PtrInterface(I) <-> t6 -> t7

// WANT:
// Local(i) -> Local(t0)
// Local(t0) -> Local(t4), PtrInterface(testdata.I)
// PtrInterface(testdata.I) -> Local(t0), Local(t2), Local(t6)
// Local(t2) -> PtrInterface(testdata.I)
// Constant(testdata.A) -> Local(t3)
// Local(t3) -> Local(t2)
// Local(t6) -> Local(t7), PtrInterface(testdata.I)


================================================
FILE: go/callgraph/vta/testdata/src/stores_arrays.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type I interface {
	Foo()
}

type J interface {
	Foo()
	Bar()
}

type B struct {
	p int
}

func (b B) Foo() {}
func (b B) Bar() {}

func Baz(b *B, S []*I, s []J) {
	var x [3]I
	x[1] = b

	a := &s[2]
	(*a).Bar()

	print([3]*I{nil, nil, nil}[2])
}

// Relevant SSA:
// func Baz(b *B, S []*I, s []J):
//   t0 = local [3]I (x)
//   t1 = &t0[1:int]
//   ...
//   t3 = &s[2:int]
//   t4 = *t3
//   ...
//   t6 = local [3]*I (complit)
//   t7 = &t6[0:int]
//         ...
//   t11 = t10[2:int]
//   ...

// WANT:
// Slice([]testdata.I) -> Local(t1)
// Local(t1) -> Slice([]testdata.I)
// Slice([]testdata.J) -> Local(t3)
// Local(t3) -> Local(t4), Slice([]testdata.J)
// Local(t11) -> Slice([]*testdata.I)
// Slice([]*testdata.I) -> Local(t11), PtrInterface(testdata.I)
// Constant(*testdata.I) -> PtrInterface(testdata.I)


================================================
FILE: go/callgraph/vta/testdata/src/t/t.go
================================================
package t

import "d"

func t(i int) int {
	data := d.Data{V: i}
	return d.D(i) + data.Do()
}


================================================
FILE: go/callgraph/vta/testdata/src/type_assertions.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

// Test program for testing type assertions and extract instructions.
// The latter are tested here too since extract instruction comes
// naturally in type assertions.

type I interface {
	Foo()
}

type J interface {
	Foo()
	Bar()
}

type A struct {
	c int
}

func (a A) Foo() {}
func (a A) Bar() {}

func Baz(i I) {
	j, ok := i.(J)
	if ok {
		j.Foo()
	}

	a := i.(*A)
	a.Bar()
}

// Relevant SSA:
// 	func Baz(i I):
//    t0 = typeassert,ok i.(J)
//    t1 = extract t0 #0
//    t2 = extract t0 #1
//    if t2 goto 1 else 2
//  1:
//    t3 = invoke t1.Foo()
//    jump 2
//  2:
//    t4 = typeassert i.(*A)  // no flow since t4 is of concrete type
//    t5 = *t4
//    t6 = (A).Bar(t5)
//    return

// WANT:
// Local(i) -> Local(t0[0])
// Local(t0[0]) -> Local(t1)


================================================
FILE: go/callgraph/vta/testdata/src/type_conversions.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:build ignore

package testdata

type Y interface {
	Foo()
	Bar(float64)
}

type Z Y

type W interface {
	Y
}

type A struct{}

func (a A) Foo()          { print("A:Foo") }
func (a A) Bar(f float64) { print(uint(f)) }

type B struct{}

func (b B) Foo()          { print("B:Foo") }
func (b B) Bar(f float64) { print(uint(f) + 1) }

type X interface {
	Foo()
}

func Baz(y Y) {
	z := Z(y)
	z.Foo()

	x := X(y)
	x.Foo()

	y = A{}
	var y_p *Y = &y

	w_p := (*W)(y_p)
	*w_p = B{}

	(*y_p).Foo() // prints B:Foo
	(*w_p).Foo() // prints B:Foo
}

// Relevant SSA:
//  func Baz(y Y):
//   t0 = new Y (y)
//   *t0 = y
//   t1 = *t0
//   t2 = changetype Z <- Y (t1)
//   t3 = invoke t2.Foo()
//
//   t4 = *t0
//   t5 = change interface X <- Y (t4)
//   t6 = invoke t5.Foo()
//
//   t7 = make Y <- A (struct{}{}:A)
//   *t0 = t7
//   t8 = changetype *W <- *Y (t0)
//   t9 = make W <- B (struct{}{}:B)
//   *t8 = t9
//   t10 = *t0
//   t11 = invoke t10.Foo()
//   t12 = *t8
//   t13 = invoke t12.Foo()
//   return

// WANT:
// Local(t1) -> Local(t2)
// Local(t4) -> Local(t5)
// Local(t0) -> Local(t1), Local(t10), Local(t4), Local(t8)
// Local(y) -> Local(t0)
// Constant(testdata.A) -> Local(t7)
// Local(t7) -> Local(t0)
// Local(t9) -> Local(t8)


================================================
FILE: go/callgraph/vta/utils.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"go/types"
	"iter"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/typeparams"
)

func canAlias(n1, n2 node) bool {
	return isReferenceNode(n1) && isReferenceNode(n2)
}

func isReferenceNode(n node) bool {
	if _, ok := n.(nestedPtrInterface); ok {
		return true
	}
	if _, ok := n.(nestedPtrFunction); ok {
		return true
	}

	if _, ok := types.Unalias(n.Type()).(*types.Pointer); ok {
		return true
	}

	return false
}

// hasInFlow checks if a concrete type can flow to node `n`.
// Returns yes iff the type of `n` satisfies one the following:
//  1. is an interface
//  2. is a (nested) pointer to interface (needed for, say,
//     slice elements of nested pointers to interface type)
//  3. is a function type (needed for higher-order type flow)
//  4. is a (nested) pointer to function (needed for, say,
//     slice elements of nested pointers to function type)
//  5. is a global Recover or Panic node
func hasInFlow(n node) bool {
	if _, ok := n.(panicArg); ok {
		return true
	}
	if _, ok := n.(recoverReturn); ok {
		return true
	}

	t := n.Type()

	if i := interfaceUnderPtr(t); i != nil {
		return true
	}
	if f := functionUnderPtr(t); f != nil {
		return true
	}

	return types.IsInterface(t) || isFunction(t)
}

func isFunction(t types.Type) bool {
	_, ok := t.Underlying().(*types.Signature)
	return ok
}

// interfaceUnderPtr checks if type `t` is a potentially nested
// pointer to interface and if yes, returns the interface type.
// Otherwise, returns nil.
func interfaceUnderPtr(t types.Type) types.Type {
	seen := make(map[types.Type]bool)
	var visit func(types.Type) types.Type
	visit = func(t types.Type) types.Type {
		if seen[t] {
			return nil
		}
		seen[t] = true

		p, ok := t.Underlying().(*types.Pointer)
		if !ok {
			return nil
		}

		if types.IsInterface(p.Elem()) {
			return p.Elem()
		}

		return visit(p.Elem())
	}
	return visit(t)
}

// functionUnderPtr checks if type `t` is a potentially nested
// pointer to function type and if yes, returns the function type.
// Otherwise, returns nil.
func functionUnderPtr(t types.Type) types.Type {
	seen := make(map[types.Type]bool)
	var visit func(types.Type) types.Type
	visit = func(t types.Type) types.Type {
		if seen[t] {
			return nil
		}
		seen[t] = true

		p, ok := t.Underlying().(*types.Pointer)
		if !ok {
			return nil
		}

		if isFunction(p.Elem()) {
			return p.Elem()
		}

		return visit(p.Elem())
	}
	return visit(t)
}

// sliceArrayElem returns the element type of type `t` that is
// expected to be a (pointer to) array, slice or string, consistent with
// the ssa.Index and ssa.IndexAddr instructions. Panics otherwise.
func sliceArrayElem(t types.Type) types.Type {
	switch u := t.Underlying().(type) {
	case *types.Pointer:
		switch e := u.Elem().Underlying().(type) {
		case *types.Array:
			return e.Elem()
		case *types.Interface:
			return sliceArrayElem(e) // e is a type param with matching element types.
		default:
			panic(t)
		}
	case *types.Array:
		return u.Elem()
	case *types.Slice:
		return u.Elem()
	case *types.Basic:
		return types.Typ[types.Byte]
	case *types.Interface: // type param.
		terms, err := typeparams.InterfaceTermSet(u)
		if err != nil || len(terms) == 0 {
			panic(t)
		}
		return sliceArrayElem(terms[0].Type()) // Element types must match.
	default:
		panic(t)
	}
}

// siteCallees returns an iterator for the callees for call site `c`.
func siteCallees(c ssa.CallInstruction, callees calleesFunc) iter.Seq[*ssa.Function] {
	return func(yield func(*ssa.Function) bool) {
		for _, callee := range callees(c) {
			if !yield(callee) {
				return
			}
		}
	}
}

func canHaveMethods(t types.Type) bool {
	t = types.Unalias(t)
	if _, ok := t.(*types.Named); ok {
		return true
	}

	u := t.Underlying()
	switch u.(type) {
	case *types.Interface, *types.Signature, *types.Struct:
		return true
	default:
		return false
	}
}

// calls returns the set of call instructions in `f`.
func calls(f *ssa.Function) []ssa.CallInstruction {
	var calls []ssa.CallInstruction
	for _, bl := range f.Blocks {
		for _, instr := range bl.Instrs {
			if c, ok := instr.(ssa.CallInstruction); ok {
				calls = append(calls, c)
			}
		}
	}
	return calls
}


================================================
FILE: go/callgraph/vta/vta.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package vta computes the call graph of a Go program using the Variable
// Type Analysis (VTA) algorithm originally described in "Practical Virtual
// Method Call Resolution for Java," Vijay Sundaresan, Laurie Hendren,
// Chrislain Razafimahefa, Raja Vallée-Rai, Patrick Lam, Etienne Gagnon, and
// Charles Godin.
//
// Note: this package is in experimental phase and its interface is
// subject to change.
// TODO(zpavlinovic): reiterate on documentation.
//
// The VTA algorithm overapproximates the set of types (and function literals)
// a variable can take during runtime by building a global type propagation
// graph and propagating types (and function literals) through the graph.
//
// A type propagation is a directed, labeled graph. A node can represent
// one of the following:
//   - A field of a struct type.
//   - A local (SSA) variable of a method/function.
//   - All pointers to a non-interface type.
//   - The return value of a method.
//   - All elements in an array.
//   - All elements in a slice.
//   - All elements in a map.
//   - All elements in a channel.
//   - A global variable.
//
// In addition, the implementation used in this package introduces
// a few Go specific kinds of nodes:
//   - (De)references of nested pointers to interfaces are modeled
//     as a unique nestedPtrInterface node in the type propagation graph.
//   - Each function literal is represented as a function node whose
//     internal value is the (SSA) representation of the function. This
//     is done to precisely infer flow of higher-order functions.
//
// Edges in the graph represent flow of types (and function literals) through
// the program. That is, the model 1) typing constraints that are induced by
// assignment statements or function and method calls and 2) higher-order flow
// of functions in the program.
//
// The labeling function maps each node to a set of types and functions that
// can intuitively reach the program construct the node represents. Initially,
// every node is assigned a type corresponding to the program construct it
// represents. Function nodes are also assigned the function they represent.
// The labeling function then propagates types and function through the graph.
//
// The result of VTA is a type propagation graph in which each node is labeled
// with a conservative overapproximation of the set of types (and functions)
// it may have. This information is then used to construct the call graph.
// For each unresolved call site, vta uses the set of types and functions
// reaching the node representing the call site to create a set of callees.
package vta

// TODO(zpavlinovic): update VTA for how it handles generic function bodies and instantiation wrappers.

import (
	"go/types"

	"golang.org/x/tools/go/callgraph"
	"golang.org/x/tools/go/ssa"
)

// CallGraph uses the VTA algorithm to compute call graph for all functions
// f:true in funcs. VTA refines the results of initial call graph and uses it
// to establish interprocedural type flow. If initial is nil, VTA uses a more
// efficient approach to construct a CHA call graph.
//
// The resulting graph does not have a root node.
//
// CallGraph does not make any assumptions on initial types global variables
// and function/method inputs can have. CallGraph is then sound, modulo use of
// reflection and unsafe, if the initial call graph is sound.
func CallGraph(funcs map[*ssa.Function]bool, initial *callgraph.Graph) *callgraph.Graph {
	callees := makeCalleesFunc(funcs, initial)
	vtaG, canon := typePropGraph(funcs, callees)
	types := propagate(vtaG, canon)

	c := &constructor{types: types, callees: callees, cache: make(methodCache)}
	return c.construct(funcs)
}

// constructor type linearly traverses the input program
// and constructs a callgraph based on the results of the
// VTA type propagation phase.
type constructor struct {
	types   propTypeMap
	cache   methodCache
	callees calleesFunc
}

func (c *constructor) construct(funcs map[*ssa.Function]bool) *callgraph.Graph {
	cg := &callgraph.Graph{Nodes: make(map[*ssa.Function]*callgraph.Node)}
	for f, in := range funcs {
		if in {
			c.constrct(cg, f)
		}
	}
	return cg
}

func (c *constructor) constrct(g *callgraph.Graph, f *ssa.Function) {
	caller := g.CreateNode(f)
	for _, call := range calls(f) {
		for _, c := range c.resolves(call) {
			callgraph.AddEdge(caller, call, g.CreateNode(c))
		}
	}
}

// resolves computes the set of functions to which VTA resolves `c`. The resolved
// functions are intersected with functions to which `c.initial` resolves `c`.
func (c *constructor) resolves(call ssa.CallInstruction) []*ssa.Function {
	cc := call.Common()
	if cc.StaticCallee() != nil {
		return []*ssa.Function{cc.StaticCallee()}
	}

	// Skip builtins as they are not *ssa.Function.
	if _, ok := cc.Value.(*ssa.Builtin); ok {
		return nil
	}

	// Cover the case of dynamic higher-order and interface calls.
	var res []*ssa.Function
	resolved := resolve(call, c.types, c.cache)
	for f := range siteCallees(call, c.callees) {
		if _, ok := resolved[f]; ok {
			res = append(res, f)
		}
	}
	return res
}

// resolve returns a set of functions `c` resolves to based on the
// type propagation results in `types`.
func resolve(c ssa.CallInstruction, types propTypeMap, cache methodCache) map[*ssa.Function]empty {
	fns := make(map[*ssa.Function]empty)
	n := local{val: c.Common().Value}
	for p := range types.propTypes(n) {
		for _, f := range propFunc(p, c, cache) {
			fns[f] = empty{}
		}
	}
	return fns
}

// propFunc returns the functions modeled with the propagation type `p`
// assigned to call site `c`. If no such function exists, nil is returned.
func propFunc(p propType, c ssa.CallInstruction, cache methodCache) []*ssa.Function {
	if p.f != nil {
		return []*ssa.Function{p.f}
	}

	if c.Common().Method == nil {
		return nil
	}

	return cache.methods(p.typ, c.Common().Method.Name(), c.Parent().Prog)
}

// methodCache serves as a type -> method name -> methods
// cache when computing methods of a type using the
// ssa.Program.MethodSets and ssa.Program.MethodValue
// APIs. The cache is used to speed up querying of
// methods of a type as the mentioned APIs are expensive.
type methodCache map[types.Type]map[string][]*ssa.Function

// methods returns methods of a type `t` named `name`. First consults
// `mc` and otherwise queries `prog` for the method. If no such method
// exists, nil is returned.
func (mc methodCache) methods(t types.Type, name string, prog *ssa.Program) []*ssa.Function {
	if ms, ok := mc[t]; ok {
		return ms[name]
	}

	ms := make(map[string][]*ssa.Function)
	mset := prog.MethodSets.MethodSet(t)
	for i, n := 0, mset.Len(); i < n; i++ {
		// f can be nil when t is an interface or some
		// other type without any runtime methods.
		if f := prog.MethodValue(mset.At(i)); f != nil {
			ms[f.Name()] = append(ms[f.Name()], f)
		}
	}
	mc[t] = ms
	return ms[name]
}


================================================
FILE: go/callgraph/vta/vta_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vta

import (
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/analysis/passes/buildssa"
	"golang.org/x/tools/go/callgraph/cha"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
)

func TestVTACallGraph(t *testing.T) {
	errDiff := func(t *testing.T, want, got, missing []string) {
		t.Errorf("got:\n%s\n\nwant:\n%s\n\nmissing:\n%s\n\ndiff:\n%s",
			strings.Join(got, "\n"),
			strings.Join(want, "\n"),
			strings.Join(missing, "\n"),
			cmp.Diff(got, want)) // to aid debugging
	}

	files := []string{
		"testdata/src/callgraph_static.go",
		"testdata/src/callgraph_ho.go",
		"testdata/src/callgraph_interfaces.go",
		"testdata/src/callgraph_pointers.go",
		"testdata/src/callgraph_collections.go",
		"testdata/src/callgraph_fields.go",
		"testdata/src/callgraph_field_funcs.go",
		"testdata/src/callgraph_recursive_types.go",
		"testdata/src/callgraph_issue_57756.go",
		"testdata/src/callgraph_comma_maps.go",
		"testdata/src/callgraph_type_aliases.go", // https://github.com/golang/go/issues/68799
	}
	if testenv.Go1Point() >= 23 {
		files = append(files, "testdata/src/callgraph_range_over_func.go")
	}

	for _, file := range files {
		t.Run(file, func(t *testing.T) {
			prog, want, err := testProg(t, file, ssa.BuilderMode(0))
			if err != nil {
				t.Fatalf("couldn't load test file '%s': %s", file, err)
			}
			if len(want) == 0 {
				t.Fatalf("couldn't find want in `%s`", file)
			}

			// First test VTA with lazy-CHA initial call graph.
			g := CallGraph(ssautil.AllFunctions(prog), nil)
			got := callGraphStr(g)
			if missing := setdiff(want, got); len(missing) > 0 {
				errDiff(t, want, got, missing)
			}

			// Repeat the test with explicit CHA initial call graph.
			g = CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
			got = callGraphStr(g)
			if missing := setdiff(want, got); len(missing) > 0 {
				errDiff(t, want, got, missing)
			}
		})
	}
}

// TestVTAProgVsFuncSet exemplifies and tests different possibilities
// enabled by having an arbitrary function set as input to CallGraph
// instead of the whole program (i.e., ssautil.AllFunctions(prog)).
func TestVTAProgVsFuncSet(t *testing.T) {
	prog, want, err := testProg(t, "testdata/src/callgraph_nested_ptr.go", ssa.BuilderMode(0))
	if err != nil {
		t.Fatalf("couldn't load test `testdata/src/callgraph_nested_ptr.go`: %s", err)
	}
	if len(want) == 0 {
		t.Fatal("couldn't find want in `testdata/src/callgraph_nested_ptr.go`")
	}

	allFuncs := ssautil.AllFunctions(prog)
	g := CallGraph(allFuncs, cha.CallGraph(prog))
	// VTA over the whole program will produce a call graph that
	// includes Baz:(**i).Foo -> A.Foo, B.Foo.
	got := callGraphStr(g)
	if diff := setdiff(want, got); len(diff) > 0 {
		t.Errorf("computed callgraph %v should contain %v (diff: %v)", got, want, diff)
	}

	// Prune the set of program functions to exclude Bar(). This should
	// yield a call graph that includes different set of callees for Baz
	// Baz:(**i).Foo -> A.Foo
	//
	// Note that the exclusion of Bar can happen, for instance, if Baz is
	// considered an entry point of some data flow analysis and Bar is
	// provably (e.g., using CHA forward reachability) unreachable from Baz.
	noBarFuncs := make(map[*ssa.Function]bool)
	for f, in := range allFuncs {
		noBarFuncs[f] = in && (funcName(f) != "Bar")
	}
	want = []string{"Baz: Do(i) -> Do; invoke t2.Foo() -> A.Foo"}
	g = CallGraph(noBarFuncs, cha.CallGraph(prog))
	got = callGraphStr(g)
	if diff := setdiff(want, got); len(diff) > 0 {
		t.Errorf("pruned callgraph %v should contain %v (diff: %v)", got, want, diff)
	}
}

// TestVTAPanicMissingDefinitions tests if VTA gracefully handles the case
// where VTA panics when a definition of a function or method is not
// available, which can happen when using analysis package. A successful
// test simply does not panic.
func TestVTAPanicMissingDefinitions(t *testing.T) {
	run := func(pass *analysis.Pass) (any, error) {
		s := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
		CallGraph(ssautil.AllFunctions(s.Pkg.Prog), cha.CallGraph(s.Pkg.Prog))
		return nil, nil
	}

	analyzer := &analysis.Analyzer{
		Name: "test",
		Doc:  "test",
		Run:  run,
		Requires: []*analysis.Analyzer{
			buildssa.Analyzer,
		},
	}

	testdata := analysistest.TestData()
	res := analysistest.Run(t, testdata, analyzer, "t", "d")
	if len(res) != 2 {
		t.Errorf("want analysis results for 2 packages; got %v", len(res))
	}
	for _, r := range res {
		if r.Err != nil {
			t.Errorf("want no error for package %v; got %v", r.Action.Package.Types.Path(), r.Err)
		}
	}
}

func TestVTACallGraphGenerics(t *testing.T) {
	// TODO(zpavlinovic): add more tests
	files := []string{
		"testdata/src/arrays_generics.go",
		"testdata/src/callgraph_generics.go",
		"testdata/src/issue63146.go",
	}
	for _, file := range files {
		t.Run(file, func(t *testing.T) {
			prog, want, err := testProg(t, file, ssa.InstantiateGenerics)
			if err != nil {
				t.Fatalf("couldn't load test file '%s': %s", file, err)
			}
			if len(want) == 0 {
				t.Fatalf("couldn't find want in `%s`", file)
			}

			g := CallGraph(ssautil.AllFunctions(prog), cha.CallGraph(prog))
			got := callGraphStr(g)
			if diff := setdiff(want, got); len(diff) != 0 {
				t.Errorf("computed callgraph %v should contain %v (diff: %v)", got, want, diff)
				logFns(t, prog)
			}
		})
	}
}

func TestVTACallGraphGo117(t *testing.T) {
	file := "testdata/src/go117.go"
	prog, want, err := testProg(t, file, ssa.BuilderMode(0))
	if err != nil {
		t.Fatalf("couldn't load test file '%s': %s", file, err)
	}
	if len(want) == 0 {
		t.Fatalf("couldn't find want in `%s`", file)
	}

	g, _ := typePropGraph(ssautil.AllFunctions(prog), makeCalleesFunc(nil, cha.CallGraph(prog)))
	got := vtaGraphStr(g)
	if diff := setdiff(want, got); len(diff) != 0 {
		t.Errorf("`%s`: want superset of %v;\n got %v", file, want, got)
	}
}


================================================
FILE: go/cfg/builder.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cfg

// This file implements the CFG construction pass.

import (
	"fmt"
	"go/ast"
	"go/token"
)

type builder struct {
	blocks    []*Block
	mayReturn func(*ast.CallExpr) bool
	current   *Block
	lblocks   map[string]*lblock // labeled blocks
	targets   *targets           // linked stack of branch targets
}

func (b *builder) stmt(_s ast.Stmt) {
	// The label of the current statement.  If non-nil, its _goto
	// target is always set; its _break and _continue are set only
	// within the body of switch/typeswitch/select/for/range.
	// It is effectively an additional default-nil parameter of stmt().
	var label *lblock
start:
	switch s := _s.(type) {
	case *ast.BadStmt,
		*ast.SendStmt,
		*ast.IncDecStmt,
		*ast.GoStmt,
		*ast.EmptyStmt,
		*ast.AssignStmt:
		// No effect on control flow.
		b.add(s)

	case *ast.DeferStmt:
		b.add(s)
		// Assume conservatively that this behaves like:
		//    defer func() { recover() }
		// so any subsequent panic may act like a return.
		b.current.returns = true

	case *ast.ExprStmt:
		b.add(s)
		if call, ok := s.X.(*ast.CallExpr); ok && !b.mayReturn(call) {
			// Calls to panic, os.Exit, etc, never return.
			b.current = b.newBlock(KindUnreachable, s)
		}

	case *ast.DeclStmt:
		// Treat each var ValueSpec as a separate statement.
		d := s.Decl.(*ast.GenDecl)
		if d.Tok == token.VAR {
			for _, spec := range d.Specs {
				if spec, ok := spec.(*ast.ValueSpec); ok {
					b.add(spec)
				}
			}
		}

	case *ast.LabeledStmt:
		label = b.labeledBlock(s.Label, s)
		b.jump(label._goto)
		b.current = label._goto
		_s = s.Stmt
		goto start // effectively: tailcall stmt(g, s.Stmt, label)

	case *ast.ReturnStmt:
		b.current.returns = true
		b.add(s)
		b.current = b.newBlock(KindUnreachable, s)

	case *ast.BranchStmt:
		b.branchStmt(s)

	case *ast.BlockStmt:
		b.stmtList(s.List)

	case *ast.IfStmt:
		if s.Init != nil {
			b.stmt(s.Init)
		}
		then := b.newBlock(KindIfThen, s)
		done := b.newBlock(KindIfDone, s)
		_else := done
		if s.Else != nil {
			_else = b.newBlock(KindIfElse, s)
		}
		b.add(s.Cond)
		b.ifelse(then, _else)
		b.current = then
		b.stmt(s.Body)
		b.jump(done)

		if s.Else != nil {
			b.current = _else
			b.stmt(s.Else)
			b.jump(done)
		}

		b.current = done

	case *ast.SwitchStmt:
		b.switchStmt(s, label)

	case *ast.TypeSwitchStmt:
		b.typeSwitchStmt(s, label)

	case *ast.SelectStmt:
		b.selectStmt(s, label)

	case *ast.ForStmt:
		b.forStmt(s, label)

	case *ast.RangeStmt:
		b.rangeStmt(s, label)

	default:
		panic(fmt.Sprintf("unexpected statement kind: %T", s))
	}
}

func (b *builder) stmtList(list []ast.Stmt) {
	for _, s := range list {
		b.stmt(s)
	}
}

func (b *builder) branchStmt(s *ast.BranchStmt) {
	var block *Block
	switch s.Tok {
	case token.BREAK:
		if s.Label != nil {
			if lb := b.labeledBlock(s.Label, nil); lb != nil {
				block = lb._break
			}
		} else {
			for t := b.targets; t != nil && block == nil; t = t.tail {
				block = t._break
			}
		}

	case token.CONTINUE:
		if s.Label != nil {
			if lb := b.labeledBlock(s.Label, nil); lb != nil {
				block = lb._continue
			}
		} else {
			for t := b.targets; t != nil && block == nil; t = t.tail {
				block = t._continue
			}
		}

	case token.FALLTHROUGH:
		for t := b.targets; t != nil && block == nil; t = t.tail {
			block = t._fallthrough
		}

	case token.GOTO:
		if s.Label != nil {
			block = b.labeledBlock(s.Label, nil)._goto
		}
	}
	if block == nil { // ill-typed (e.g. undefined label)
		block = b.newBlock(KindUnreachable, s)
	}
	b.jump(block)
	b.current = b.newBlock(KindUnreachable, s)
}

func (b *builder) switchStmt(s *ast.SwitchStmt, label *lblock) {
	if s.Init != nil {
		b.stmt(s.Init)
	}
	if s.Tag != nil {
		b.add(s.Tag)
	}
	done := b.newBlock(KindSwitchDone, s)
	if label != nil {
		label._break = done
	}
	// We pull the default case (if present) down to the end.
	// But each fallthrough label must point to the next
	// body block in source order, so we preallocate a
	// body block (fallthru) for the next case.
	// Unfortunately this makes for a confusing block order.
	var defaultBody *[]ast.Stmt
	var defaultFallthrough *Block
	var fallthru, defaultBlock *Block
	ncases := len(s.Body.List)
	for i, clause := range s.Body.List {
		body := fallthru
		if body == nil {
			body = b.newBlock(KindSwitchCaseBody, clause) // first case only
		}

		// Preallocate body block for the next case.
		fallthru = done
		if i+1 < ncases {
			fallthru = b.newBlock(KindSwitchCaseBody, s.Body.List[i+1])
		}

		cc := clause.(*ast.CaseClause)
		if cc.List == nil {
			// Default case.
			defaultBody = &cc.Body
			defaultFallthrough = fallthru
			defaultBlock = body
			continue
		}

		var nextCond *Block
		for _, cond := range cc.List {
			nextCond = b.newBlock(KindSwitchNextCase, cc)
			b.add(cond) // one half of the tag==cond condition
			b.ifelse(body, nextCond)
			b.current = nextCond
		}
		b.current = body
		b.targets = &targets{
			tail:         b.targets,
			_break:       done,
			_fallthrough: fallthru,
		}
		b.stmtList(cc.Body)
		b.targets = b.targets.tail
		b.jump(done)
		b.current = nextCond
	}
	if defaultBlock != nil {
		b.jump(defaultBlock)
		b.current = defaultBlock
		b.targets = &targets{
			tail:         b.targets,
			_break:       done,
			_fallthrough: defaultFallthrough,
		}
		b.stmtList(*defaultBody)
		b.targets = b.targets.tail
	}
	b.jump(done)
	b.current = done
}

func (b *builder) typeSwitchStmt(s *ast.TypeSwitchStmt, label *lblock) {
	if s.Init != nil {
		b.stmt(s.Init)
	}
	if s.Assign != nil {
		b.add(s.Assign)
	}

	done := b.newBlock(KindSwitchDone, s)
	if label != nil {
		label._break = done
	}
	var default_ *ast.CaseClause
	for _, clause := range s.Body.List {
		cc := clause.(*ast.CaseClause)
		if cc.List == nil {
			default_ = cc
			continue
		}
		body := b.newBlock(KindSwitchCaseBody, cc)
		var next *Block
		for _, casetype := range cc.List {
			next = b.newBlock(KindSwitchNextCase, cc)
			// casetype is a type, so don't call b.add(casetype).
			// This block logically contains a type assertion,
			// x.(casetype), but it's unclear how to represent x.
			_ = casetype
			b.ifelse(body, next)
			b.current = next
		}
		b.current = body
		b.typeCaseBody(cc, done)
		b.current = next
	}
	if default_ != nil {
		b.typeCaseBody(default_, done)
	} else {
		b.jump(done)
	}
	b.current = done
}

func (b *builder) typeCaseBody(cc *ast.CaseClause, done *Block) {
	b.targets = &targets{
		tail:   b.targets,
		_break: done,
	}
	b.stmtList(cc.Body)
	b.targets = b.targets.tail
	b.jump(done)
}

func (b *builder) selectStmt(s *ast.SelectStmt, label *lblock) {
	// First evaluate channel expressions.
	// TODO(adonovan): fix: evaluate only channel exprs here.
	for _, clause := range s.Body.List {
		if comm := clause.(*ast.CommClause).Comm; comm != nil {
			b.stmt(comm)
		}
	}

	done := b.newBlock(KindSelectDone, s)
	if label != nil {
		label._break = done
	}

	var defaultBody *[]ast.Stmt
	for _, cc := range s.Body.List {
		clause := cc.(*ast.CommClause)
		if clause.Comm == nil {
			defaultBody = &clause.Body
			continue
		}
		body := b.newBlock(KindSelectCaseBody, clause)
		next := b.newBlock(KindSelectAfterCase, clause)
		b.ifelse(body, next)
		b.current = body
		b.targets = &targets{
			tail:   b.targets,
			_break: done,
		}
		switch comm := clause.Comm.(type) {
		case *ast.ExprStmt: // <-ch
			// nop
		case *ast.AssignStmt: // x := <-states[state].Chan
			b.add(comm.Lhs[0])
		}
		b.stmtList(clause.Body)
		b.targets = b.targets.tail
		b.jump(done)
		b.current = next
	}
	if defaultBody != nil {
		b.targets = &targets{
			tail:   b.targets,
			_break: done,
		}
		b.stmtList(*defaultBody)
		b.targets = b.targets.tail
		b.jump(done)
	}
	b.current = done
}

func (b *builder) forStmt(s *ast.ForStmt, label *lblock) {
	//	...init...
	//      jump loop
	// loop:
	//      if cond goto body else done
	// body:
	//      ...body...
	//      jump post
	// post:				 (target of continue)
	//      ...post...
	//      jump loop
	// done:                                 (target of break)
	if s.Init != nil {
		b.stmt(s.Init)
	}
	body := b.newBlock(KindForBody, s)
	done := b.newBlock(KindForDone, s) // target of 'break'
	loop := body                       // target of back-edge
	if s.Cond != nil {
		loop = b.newBlock(KindForLoop, s)
	}
	cont := loop // target of 'continue'
	if s.Post != nil {
		cont = b.newBlock(KindForPost, s)
	}
	if label != nil {
		label._break = done
		label._continue = cont
	}
	b.jump(loop)
	b.current = loop
	if loop != body {
		b.add(s.Cond)
		b.ifelse(body, done)
		b.current = body
	}
	b.targets = &targets{
		tail:      b.targets,
		_break:    done,
		_continue: cont,
	}
	b.stmt(s.Body)
	b.targets = b.targets.tail
	b.jump(cont)

	if s.Post != nil {
		b.current = cont
		b.stmt(s.Post)
		b.jump(loop) // back-edge
	}
	b.current = done
}

func (b *builder) rangeStmt(s *ast.RangeStmt, label *lblock) {
	b.add(s.X)

	if s.Key != nil {
		b.add(s.Key)
	}
	if s.Value != nil {
		b.add(s.Value)
	}

	//      ...
	// loop:                                   (target of continue)
	// 	if ... goto body else done
	// body:
	//      ...
	// 	jump loop
	// done:                                   (target of break)

	loop := b.newBlock(KindRangeLoop, s)
	b.jump(loop)
	b.current = loop

	body := b.newBlock(KindRangeBody, s)
	done := b.newBlock(KindRangeDone, s)
	b.ifelse(body, done)
	b.current = body

	if label != nil {
		label._break = done
		label._continue = loop
	}
	b.targets = &targets{
		tail:      b.targets,
		_break:    done,
		_continue: loop,
	}
	b.stmt(s.Body)
	b.targets = b.targets.tail
	b.jump(loop) // back-edge
	b.current = done
}

// -------- helpers --------

// Destinations associated with unlabeled for/switch/select stmts.
// We push/pop one of these as we enter/leave each construct and for
// each BranchStmt we scan for the innermost target of the right type.
type targets struct {
	tail         *targets // rest of stack
	_break       *Block
	_continue    *Block
	_fallthrough *Block
}

// Destinations associated with a labeled block.
// We populate these as labels are encountered in forward gotos or
// labeled statements.
type lblock struct {
	_goto     *Block
	_break    *Block
	_continue *Block
}

// labeledBlock returns the branch target associated with the
// specified label, creating it if needed.
func (b *builder) labeledBlock(label *ast.Ident, stmt *ast.LabeledStmt) *lblock {
	lb := b.lblocks[label.Name]
	if lb == nil {
		lb = &lblock{_goto: b.newBlock(KindLabel, nil)}
		if b.lblocks == nil {
			b.lblocks = make(map[string]*lblock)
		}
		b.lblocks[label.Name] = lb
	}
	// Fill in the label later (in case of forward goto).
	// Stmt may be set already if labels are duplicated (ill-typed).
	if stmt != nil && lb._goto.Stmt == nil {
		lb._goto.Stmt = stmt
	}
	return lb
}

// newBlock appends a new unconnected basic block to b.cfg's block
// slice and returns it.
// It does not automatically become the current block.
// comment is an optional string for more readable debugging output.
func (b *builder) newBlock(kind BlockKind, stmt ast.Stmt) *Block {
	block := &Block{
		Index: int32(len(b.blocks)),
		Kind:  kind,
		Stmt:  stmt,
	}
	block.Succs = block.succs2[:0]
	b.blocks = append(b.blocks, block)
	return block
}

func (b *builder) add(n ast.Node) {
	b.current.Nodes = append(b.current.Nodes, n)
}

// jump adds an edge from the current block to the target block,
// and sets b.current to nil.
func (b *builder) jump(target *Block) {
	b.current.Succs = append(b.current.Succs, target)
	b.current = nil
}

// ifelse emits edges from the current block to the t and f blocks,
// and sets b.current to nil.
func (b *builder) ifelse(t, f *Block) {
	b.current.Succs = append(b.current.Succs, t, f)
	b.current = nil
}


================================================
FILE: go/cfg/cfg.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cfg constructs a simple control-flow graph (CFG) of the
// statements and expressions within a single function.
//
// Use cfg.New to construct the CFG for a function body.
//
// The blocks of the CFG contain all the function's non-control
// statements.  The CFG does not contain control statements such as If,
// Switch, Select, and Branch, but does contain their subexpressions;
// also, each block records the control statement (Block.Stmt) that
// gave rise to it and its relationship (Block.Kind) to that statement.
//
// For example, this source code:
//
//	if x := f(); x != nil {
//		T()
//	} else {
//		F()
//	}
//
// produces this CFG:
//
//	1:  x := f()		Body
//	    x != nil
//	    succs: 2, 3
//	2:  T()			IfThen
//	    succs: 4
//	3:  F()			IfElse
//	    succs: 4
//	4:			IfDone
//
// The CFG does contain Return statements; even implicit returns are
// materialized (at the position of the function's closing brace).
//
// The CFG does not record conditions associated with conditional branch
// edges, nor the short-circuit semantics of the && and || operators,
// nor abnormal control flow caused by panic.  If you need this
// information, use golang.org/x/tools/go/ssa instead.
package cfg

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
)

// A CFG represents the control-flow graph of a single function.
//
// The entry point is Blocks[0]; there may be multiple return blocks.
type CFG struct {
	Blocks   []*Block // block[0] is entry; order otherwise undefined
	noreturn bool     // function body lacks a reachable return statement
}

// NoReturn reports whether the function has no reachable return.
func (cfg *CFG) NoReturn() bool { return cfg.noreturn }

// A Block represents a basic block: a list of statements and
// expressions that are always evaluated sequentially.
//
// A block may have 0-2 successors: zero for a return block or a block
// that calls a function such as panic that never returns; one for a
// normal (jump) block; and two for a conditional (if) block.
//
// In a conditional block, the last entry in Nodes is the condition and always
// an [ast.Expr], Succs[0] is the successor if the condition is true, and
// Succs[1] is the successor if the condition is false.
type Block struct {
	Nodes   []ast.Node // statements, expressions, and ValueSpecs
	Succs   []*Block   // successor nodes in the graph
	Index   int32      // index within CFG.Blocks
	Live    bool       // block is reachable from entry
	returns bool       // block contains return or defer (which may recover and return)
	Kind    BlockKind  // block kind
	Stmt    ast.Stmt   // statement that gave rise to this block (see BlockKind for details)

	succs2 [2]*Block // underlying array for Succs
}

// A BlockKind identifies the purpose of a block.
// It also determines the possible types of its Stmt field.
type BlockKind uint8

const (
	KindInvalid BlockKind = iota // Stmt=nil

	KindUnreachable     // unreachable block after {Branch,Return}Stmt / no-return call ExprStmt
	KindBody            // function body BlockStmt
	KindForBody         // body of ForStmt
	KindForDone         // block after ForStmt
	KindForLoop         // head of ForStmt
	KindForPost         // post condition of ForStmt
	KindIfDone          // block after IfStmt
	KindIfElse          // else block of IfStmt
	KindIfThen          // then block of IfStmt
	KindLabel           // labeled block of BranchStmt (Stmt may be nil for dangling label)
	KindRangeBody       // body of RangeStmt
	KindRangeDone       // block after RangeStmt
	KindRangeLoop       // head of RangeStmt
	KindSelectCaseBody  // body of SelectStmt
	KindSelectDone      // block after SelectStmt
	KindSelectAfterCase // block after a CommClause
	KindSwitchCaseBody  // body of CaseClause
	KindSwitchDone      // block after {Type.}SwitchStmt
	KindSwitchNextCase  // secondary expression of a multi-expression CaseClause
)

func (kind BlockKind) String() string {
	return [...]string{
		KindInvalid:         "Invalid",
		KindUnreachable:     "Unreachable",
		KindBody:            "Body",
		KindForBody:         "ForBody",
		KindForDone:         "ForDone",
		KindForLoop:         "ForLoop",
		KindForPost:         "ForPost",
		KindIfDone:          "IfDone",
		KindIfElse:          "IfElse",
		KindIfThen:          "IfThen",
		KindLabel:           "Label",
		KindRangeBody:       "RangeBody",
		KindRangeDone:       "RangeDone",
		KindRangeLoop:       "RangeLoop",
		KindSelectCaseBody:  "SelectCaseBody",
		KindSelectDone:      "SelectDone",
		KindSelectAfterCase: "SelectAfterCase",
		KindSwitchCaseBody:  "SwitchCaseBody",
		KindSwitchDone:      "SwitchDone",
		KindSwitchNextCase:  "SwitchNextCase",
	}[kind]
}

// New returns a new control-flow graph for the specified function body,
// which must be non-nil.
//
// The CFG builder calls mayReturn to determine whether a given function
// call may return.  For example, calls to panic, os.Exit, and log.Fatal
// do not return, so the builder can remove infeasible graph edges
// following such calls.  The builder calls mayReturn only for a
// CallExpr beneath an ExprStmt.
func New(body *ast.BlockStmt, mayReturn func(*ast.CallExpr) bool) *CFG {
	b := builder{
		mayReturn: mayReturn,
	}
	b.current = b.newBlock(KindBody, body)
	b.stmt(body)

	// Compute liveness (reachability from entry point),
	// breadth-first, marking Block.Live flags.
	q := make([]*Block, 0, len(b.blocks))
	q = append(q, b.blocks[0]) // entry point
	for len(q) > 0 {
		b := q[len(q)-1]
		q = q[:len(q)-1]

		if !b.Live {
			b.Live = true
			q = append(q, b.Succs...)
		}
	}

	// Does control fall off the end of the function's body?
	// Make implicit return explicit.
	if b.current != nil && b.current.Live {
		b.current.returns = true
		b.add(&ast.ReturnStmt{
			Return: body.End() - 1,
		})
	}

	// Is any return (or defer+recover) block reachable?
	noreturn := true
	for _, bl := range b.blocks {
		if bl.Live && bl.returns {
			noreturn = false
			break
		}
	}

	return &CFG{Blocks: b.blocks, noreturn: noreturn}
}

func (b *Block) String() string {
	return fmt.Sprintf("block %d (%s)", b.Index, b.comment(nil))
}

func (b *Block) comment(fset *token.FileSet) string {
	s := b.Kind.String()
	if fset != nil && b.Stmt != nil {
		s = fmt.Sprintf("%s@L%d", s, fset.Position(b.Stmt.Pos()).Line)
	}
	return s
}

// Return returns the return statement at the end of this block if present, nil
// otherwise.
//
// When control falls off the end of the function, the ReturnStmt is synthetic
// and its [ast.Node.End] position may be beyond the end of the file.
//
// A function that contains no return statement (explicit or implied)
// may yet return normally, and may even return a nonzero value. For example:
//
//	func() (res any) {
//		defer func() { res = recover() }()
//		panic(123)
//	}
func (b *Block) Return() (ret *ast.ReturnStmt) {
	if len(b.Nodes) > 0 {
		ret, _ = b.Nodes[len(b.Nodes)-1].(*ast.ReturnStmt)
	}
	return
}

// Format formats the control-flow graph for ease of debugging.
func (g *CFG) Format(fset *token.FileSet) string {
	var buf bytes.Buffer
	for _, b := range g.Blocks {
		fmt.Fprintf(&buf, ".%d: # %s\n", b.Index, b.comment(fset))
		for _, n := range b.Nodes {
			fmt.Fprintf(&buf, "\t%s\n", formatNode(fset, n))
		}
		if len(b.Succs) > 0 {
			fmt.Fprintf(&buf, "\tsuccs:")
			for _, succ := range b.Succs {
				fmt.Fprintf(&buf, " %d", succ.Index)
			}
			buf.WriteByte('\n')
		}
		buf.WriteByte('\n')
	}
	return buf.String()
}

// Dot returns the control-flow graph in the [Dot graph description language].
// Use a command such as 'dot -Tsvg' to render it in a form viewable in a browser.
// This method is provided as a debugging aid; the details of the
// output are unspecified and may change.
//
// [Dot graph description language]: ​​https://en.wikipedia.org/wiki/DOT_(graph_description_language)
func (g *CFG) Dot(fset *token.FileSet) string {
	var buf bytes.Buffer
	buf.WriteString("digraph CFG {\n")
	buf.WriteString("  node [shape=box];\n")
	for _, b := range g.Blocks {
		// node label
		var text bytes.Buffer
		text.WriteString(b.comment(fset))
		for _, n := range b.Nodes {
			fmt.Fprintf(&text, "\n%s", formatNode(fset, n))
		}

		// node and edges
		fmt.Fprintf(&buf, "  n%d [label=%q];\n", b.Index, &text)
		for _, succ := range b.Succs {
			fmt.Fprintf(&buf, "  n%d -> n%d;\n", b.Index, succ.Index)
		}
	}
	buf.WriteString("}\n")
	return buf.String()
}

func formatNode(fset *token.FileSet, n ast.Node) string {
	var buf bytes.Buffer
	format.Node(&buf, fset, n)
	// Indent secondary lines by a tab.
	return string(bytes.Replace(buf.Bytes(), []byte("\n"), []byte("\n\t"), -1))
}


================================================
FILE: go/cfg/cfg_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cfg_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"testing"

	"golang.org/x/tools/go/cfg"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
)

const src = `package main

import "log"

func f1() {
	live()
	return
	dead()
}

func f2() {
	for {
		live()
	}
	dead()
}

func f3() {
	if true { // even known values are ignored
		return
	}
	for true { // even known values are ignored
		live()
	}
	for {
		live()
	}
	dead()
}

func f4(x int) {
	switch x {
	case 1:
		live()
		fallthrough
	case 2:
		live()
		log.Fatal()
	default:
		panic("oops")
	}
	dead()
}

func f4(ch chan int) {
	select {
	case <-ch:
		live()
		return
	default:
		live()
		panic("oops")
	}
	dead()
}

func f5(unknown bool) {
	for {
		if unknown {
			break
		}
		continue
		dead()
	}
	live()
}

func f6(unknown bool) {
outer:
	for {
		for {
			break outer
			dead()
		}
		dead()
	}
	live()
}

func f7() {
	for {
		break nosuchlabel
		dead()
	}
	dead()
}

func f8() {
	select{}
	dead()
}

func f9(ch chan int) {
	select {
	case <-ch:
		return
	}
	dead()
}

func f10(ch chan int) {
	select {
	case <-ch:
		return
		dead()
	default:
	}
	live()
}
`

func TestDeadCode(t *testing.T) {
	// We'll use dead code detection to verify the CFG.

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "dummy.go", src, parser.Mode(0))
	if err != nil {
		t.Fatal(err)
	}
	for _, decl := range f.Decls {
		if decl, ok := decl.(*ast.FuncDecl); ok {
			g := cfg.New(decl.Body, mayReturn)

			// Print statements in unreachable blocks
			// (in order determined by builder).
			var buf bytes.Buffer
			for _, b := range g.Blocks {
				if !b.Live {
					for _, n := range b.Nodes {
						fmt.Fprintf(&buf, "\t%s\n", formatNode(fset, n))
					}
				}
			}

			// Check that the result contains "dead" at least once but not "live".
			if !bytes.Contains(buf.Bytes(), []byte("dead")) ||
				bytes.Contains(buf.Bytes(), []byte("live")) {
				t.Errorf("unexpected dead statements in function %s:\n%s",
					decl.Name.Name,
					&buf)
				t.Logf("control flow graph:\n%s", g.Format(fset))
			}
		}
	}
}

// TestSmoke runs the CFG builder on every FuncDecl in the standard
// library and x/tools. (This is all well-typed code, but it gives
// some coverage.)
func TestSmoke(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in short mode")
	}
	testenv.NeedsTool(t, "go")

	// The Mode API is just hateful.
	// https://github.com/golang/go/issues/48226#issuecomment-1948792315
	mode := packages.NeedDeps | packages.NeedImports | packages.NeedSyntax | packages.NeedTypes
	pkgs, err := packages.Load(&packages.Config{Mode: mode}, "std", "golang.org/x/tools/...")
	if err != nil {
		t.Fatal(err)
	}

	for _, pkg := range pkgs {
		for _, file := range pkg.Syntax {
			for _, decl := range file.Decls {
				if decl, ok := decl.(*ast.FuncDecl); ok && decl.Body != nil {
					g := cfg.New(decl.Body, mayReturn)

					// Run a few quick sanity checks.
					failed := false
					for i, b := range g.Blocks {
						errorf := func(format string, args ...any) {
							if !failed {
								t.Errorf("%s\n%s", pkg.Fset.Position(decl.Pos()), g.Format(pkg.Fset))
								failed = true
							}
							msg := fmt.Sprintf(format, args...)
							t.Errorf("block %d: %s", i, msg)
						}

						if b.Kind == cfg.KindInvalid {
							errorf("invalid Block.Kind %v", b.Kind)
						}
						if b.Stmt == nil && b.Kind != cfg.KindLabel {
							errorf("nil Block.Stmt (Kind=%v)", b.Kind)
						}
						if i != int(b.Index) {
							errorf("invalid Block.Index")
						}
					}
				}
			}
		}
	}
}

// A trivial mayReturn predicate that looks only at syntax, not types.
func mayReturn(call *ast.CallExpr) bool {
	switch fun := call.Fun.(type) {
	case *ast.Ident:
		return fun.Name != "panic"
	case *ast.SelectorExpr:
		return fun.Sel.Name != "Fatal"
	}
	return true
}

func formatNode(fset *token.FileSet, n ast.Node) string {
	var buf bytes.Buffer
	format.Node(&buf, fset, n)
	// Indent secondary lines by a tab.
	return string(bytes.Replace(buf.Bytes(), []byte("\n"), []byte("\n\t"), -1))
}


================================================
FILE: go/cfg/main.go
================================================
//go:build ignore

// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The cfg command prints the control-flow graph of the first function
// or method whose name matches 'funcname' in the specified package.
//
// Usage: cfg package funcname
//
// Example:
//
//	$ go build -o cfg ./go/cfg/main.go
//	$ cfg ./go/cfg stmt | dot -Tsvg > cfg.svg && open cfg.svg
package main

import (
	"flag"
	"fmt"
	"go/ast"
	"log"
	"os"

	"golang.org/x/tools/go/cfg"
	"golang.org/x/tools/go/packages"
)

func main() {
	flag.Parse()
	if len(flag.Args()) != 2 {
		log.Fatal("Usage: package funcname")
	}
	pattern, funcname := flag.Args()[0], flag.Args()[1]
	pkgs, err := packages.Load(&packages.Config{Mode: packages.LoadSyntax}, pattern)
	if err != nil {
		log.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}
	for _, pkg := range pkgs {
		for _, f := range pkg.Syntax {
			for _, decl := range f.Decls {
				if decl, ok := decl.(*ast.FuncDecl); ok {
					if decl.Name.Name == funcname {
						g := cfg.New(decl.Body, mayReturn)
						fmt.Println(g.Dot(pkg.Fset))
						os.Exit(0)
					}
				}
			}
		}
	}
	log.Fatalf("no function %q found in %s", funcname, pattern)
}

// A trivial mayReturn predicate that looks only at syntax, not types.
func mayReturn(call *ast.CallExpr) bool {
	switch fun := call.Fun.(type) {
	case *ast.Ident:
		return fun.Name != "panic"
	case *ast.SelectorExpr:
		return fun.Sel.Name != "Fatal"
	}
	return true
}


================================================
FILE: go/gccgoexportdata/gccgoexportdata.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gccgoexportdata provides functions for reading export data
// files containing type information produced by the gccgo compiler.
//
// This package is a stop-gap until such time as gccgo uses the same
// export data format as gc; see Go issue 17573. Once that occurs, this
// package will be deprecated and eventually deleted.
package gccgoexportdata

// TODO(adonovan): add Find, Write, Importer to the API,
// for symmetry with gcexportdata.

import (
	"bytes"
	"debug/elf"
	"fmt"
	"go/token"
	"go/types"
	"io"
	"strconv"
	"strings"

	"golang.org/x/tools/go/internal/gccgoimporter"
)

// CompilerInfo executes the specified gccgo compiler and returns
// information about it: its version (e.g. "4.8.0"), its target triple
// (e.g. "x86_64-unknown-linux-gnu"), and the list of directories it
// searches to find standard packages. The given arguments are passed
// directly to calls to the specified gccgo compiler.
func CompilerInfo(gccgo string, args ...string) (version, triple string, dirs []string, err error) {
	var inst gccgoimporter.GccgoInstallation
	err = inst.InitFromDriver(gccgo, args...)
	if err == nil {
		version = inst.GccVersion
		triple = inst.TargetTriple
		dirs = inst.SearchPaths()
	}
	return
}

// NewReader returns a reader for the export data section of an object
// (.o) or archive (.a) file read from r.
func NewReader(r io.Reader) (io.Reader, error) {
	data, err := io.ReadAll(r)
	if err != nil {
		return nil, err
	}

	// If the file is an archive, extract the first section.
	const archiveMagic = "!<arch>\n"
	if bytes.HasPrefix(data, []byte(archiveMagic)) {
		section, err := firstSection(data[len(archiveMagic):])
		if err != nil {
			return nil, err
		}
		data = section
	}

	// Data contains an ELF file with a .go_export section.
	// ELF magic number is "\x7fELF".
	ef, err := elf.NewFile(bytes.NewReader(data))
	if err != nil {
		return nil, err
	}
	sec := ef.Section(".go_export")
	if sec == nil {
		return nil, fmt.Errorf("no .go_export section")
	}
	return sec.Open(), nil
}

// firstSection returns the contents of the first regular file in an ELF
// archive (http://www.sco.com/developers/devspecs/gabi41.pdf, §7.2).
func firstSection(a []byte) ([]byte, error) {
	for len(a) >= 60 {
		var hdr []byte
		hdr, a = a[:60], a[60:]

		name := strings.TrimSpace(string(hdr[:16]))

		sizeStr := string(hdr[48:58])
		size, err := strconv.Atoi(strings.TrimSpace(sizeStr))
		if err != nil {
			return nil, fmt.Errorf("invalid size: %q", sizeStr)
		}

		if len(a) < size {
			return nil, fmt.Errorf("invalid section size: %d", size)
		}

		// The payload is padded to an even number of bytes.
		var payload []byte
		payload, a = a[:size], a[size+size&1:]

		// Skip special files:
		//   "/"           archive symbol table
		//   "/SYM64/"     archive symbol table on e.g. s390x
		//   "//"          archive string table (if any filename is >15 bytes)
		if name == "/" || name == "/SYM64/" || name == "//" {
			continue
		}

		return payload, nil
	}
	return nil, fmt.Errorf("archive has no regular sections")
}

// Read reads export data from in, decodes it, and returns type
// information for the package.
// The package name is specified by path.
//
// The FileSet parameter is currently unused but exists for symmetry
// with gcexportdata.
//
// Read may inspect and add to the imports map to ensure that references
// within the export data to other packages are consistent.  The caller
// must ensure that imports[path] does not exist, or exists but is
// incomplete (see types.Package.Complete), and Read inserts the
// resulting package into this map entry.
//
// On return, the state of the reader is undefined.
func Read(in io.Reader, _ *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) {
	return gccgoimporter.Parse(in, imports, path)
}


================================================
FILE: go/gccgoexportdata/gccgoexportdata_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gccgoexportdata_test

import (
	"go/types"
	"os"
	"testing"

	"golang.org/x/tools/go/gccgoexportdata"
)

// Test ensures this package can read gccgo export data from the
// .go_export from a standalone ELF file or such a file in an archive
// library.
//
// The testdata/{short,long}.a ELF archive files were produced by:
//
//	$ echo 'package foo; func F()' > foo.go
//	$ gccgo -c -fgo-pkgpath blah foo.go
//	$ objcopy -j .go_export foo.o foo.gox
//	$ ar q short.a foo.gox
//	$ objcopy -j .go_export foo.o name-longer-than-16-bytes.gox
//	$ ar q long.a name-longer-than-16-bytes.gox
//
// The file long.a contains an archive string table.
//
// The errors.gox file (an ELF object file) comes from the toolchain's
// standard library.
func Test(t *testing.T) {
	for _, test := range []struct {
		filename, path, member, wantType string
	}{
		{"testdata/errors.gox", "errors", "New", "func(text string) error"},
		{"testdata/short.a", "short", "F", "func()"},
		{"testdata/long.a", "long", "F", "func()"},
	} {
		t.Logf("filename = %s", test.filename)
		f, err := os.Open(test.filename)
		if err != nil {
			t.Error(err)
			continue
		}
		defer f.Close()
		r, err := gccgoexportdata.NewReader(f)
		if err != nil {
			t.Error(err)
			continue
		}

		imports := make(map[string]*types.Package)
		pkg, err := gccgoexportdata.Read(r, nil, imports, test.path)
		if err != nil {
			t.Error(err)
			continue
		}

		// Check type of designated package member.
		obj := pkg.Scope().Lookup(test.member)
		if obj == nil {
			t.Errorf("%s.%s not found", test.path, test.member)
			continue
		}
		if obj.Type().String() != test.wantType {
			t.Errorf("%s.%s.Type = %s, want %s",
				test.path, test.member, obj.Type(), test.wantType)
		}
	}
}


================================================
FILE: go/gcexportdata/example_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.7 && gc && !android && !ios && (unix || aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || plan9 || windows)

package gcexportdata_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"log"
	"os"
	"path/filepath"
	"slices"
	"strings"

	"golang.org/x/tools/go/gcexportdata"
)

// ExampleRead uses gcexportdata.Read to load type information for the
// "fmt" package from the fmt.a file produced by the gc compiler.
func ExampleRead() {
	// Find the export data file.
	filename, path := gcexportdata.Find("fmt", "")
	if filename == "" {
		log.Fatalf("can't find export data for fmt")
	}
	fmt.Printf("Package path:       %s\n", path)

	// Open and read the file.
	f, err := os.Open(filename)
	if err != nil {
		log.Fatal(err)
	}
	defer f.Close()
	r, err := gcexportdata.NewReader(f)
	if err != nil {
		log.Fatalf("reading export data %s: %v", filename, err)
	}

	// Decode the export data.
	fset := token.NewFileSet()
	imports := make(map[string]*types.Package)
	pkg, err := gcexportdata.Read(r, fset, imports, path)
	if err != nil {
		log.Fatal(err)
	}

	// We can see all the names in Names.
	members := pkg.Scope().Names()
	foundPrintln := slices.Contains(members, "Println")
	fmt.Print("Package members:    ")
	if foundPrintln {
		fmt.Println("Println found")
	} else {
		fmt.Println("Println not found")
	}

	// We can also look up a name directly using Lookup.
	println := pkg.Scope().Lookup("Println")
	// go 1.18+ uses the 'any' alias
	typ := strings.ReplaceAll(println.Type().String(), "interface{}", "any")
	fmt.Printf("Println type:       %s\n", typ)
	posn := fset.Position(println.Pos())
	// make example deterministic
	posn.Line = 123
	fmt.Printf("Println location:   %s\n", slashify(posn))

	// Output:
	//
	// Package path:       fmt
	// Package members:    Println found
	// Println type:       func(a ...any) (n int, err error)
	// Println location:   $GOROOT/src/fmt/print.go:123:1
}

// ExampleNewImporter demonstrates usage of NewImporter to provide type
// information for dependencies when type-checking Go source code.
func ExampleNewImporter() {
	const src = `package myrpc

// choosing a package that doesn't change across releases
import "net/rpc"

const serverError rpc.ServerError = ""
`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "myrpc.go", src, 0)
	if err != nil {
		log.Fatal(err)
	}

	packages := make(map[string]*types.Package)
	imp := gcexportdata.NewImporter(fset, packages)
	conf := types.Config{Importer: imp}
	pkg, err := conf.Check("myrpc", fset, []*ast.File{f}, nil)
	if err != nil {
		log.Fatal(err)
	}

	// object from imported package
	pi := packages["net/rpc"].Scope().Lookup("ServerError")
	fmt.Printf("type %s.%s %s // %s\n",
		pi.Pkg().Path(),
		pi.Name(),
		pi.Type().Underlying(),
		slashify(fset.Position(pi.Pos())),
	)

	// object in source package
	twopi := pkg.Scope().Lookup("serverError")
	fmt.Printf("const %s %s = %s // %s\n",
		twopi.Name(),
		twopi.Type(),
		twopi.(*types.Const).Val(),
		slashify(fset.Position(twopi.Pos())),
	)

	// Output:
	//
	// type net/rpc.ServerError string // $GOROOT/src/net/rpc/client.go:20:1
	// const serverError net/rpc.ServerError = "" // myrpc.go:6:7
}

func slashify(posn token.Position) token.Position {
	posn.Filename = filepath.ToSlash(posn.Filename) // for MS Windows portability
	return posn
}


================================================
FILE: go/gcexportdata/gcexportdata.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gcexportdata provides functions for reading and writing
// export data, which is a serialized description of the API of a Go
// package including the names, kinds, types, and locations of all
// exported declarations.
//
// The standard Go compiler (cmd/compile) writes an export data file
// for each package it compiles, which it later reads when compiling
// packages that import the earlier one. The compiler must thus
// contain logic to both write and read export data.
// (See the "Export" section in the cmd/compile/README file.)
//
// The [Read] function in this package can read files produced by the
// compiler, producing [go/types] data structures. As a matter of
// policy, Read supports export data files produced by only the last
// two Go releases plus tip; see https://go.dev/issue/68898. The
// export data files produced by the compiler contain additional
// details related to generics, inlining, and other optimizations that
// cannot be decoded by the [Read] function.
//
// In files written by the compiler, the export data is not at the
// start of the file. Before calling Read, use [NewReader] to locate
// the desired portion of the file.
//
// The [Write] function in this package encodes the exported API of a
// Go package ([types.Package]) as a file. Such files can be later
// decoded by Read, but cannot be consumed by the compiler.
//
// # Future changes
//
// Although Read supports the formats written by both Write and the
// compiler, the two are quite different, and there is an open
// proposal (https://go.dev/issue/69491) to separate these APIs.
//
// Under that proposal, this package would ultimately provide only the
// Read operation for compiler export data, which must be defined in
// this module (golang.org/x/tools), not in the standard library, to
// avoid version skew for developer tools that need to read compiler
// export data both before and after a Go release, such as from Go
// 1.23 to Go 1.24. Because this package lives in the tools module,
// clients can update their version of the module some time before the
// Go 1.24 release and rebuild and redeploy their tools, which will
// then be able to consume both Go 1.23 and Go 1.24 export data files,
// so they will work before and after the Go update. (See discussion
// at https://go.dev/issue/15651.)
//
// The operations to import and export [go/types] data structures
// would be defined in the go/types package as Import and Export.
// [Write] would (eventually) delegate to Export,
// and [Read], when it detects a file produced by Export,
// would delegate to Import.
//
// # Deprecations
//
// The [NewImporter] and [Find] functions are deprecated and should
// not be used in new code. The [WriteBundle] and [ReadBundle]
// functions are experimental, and there is an open proposal to
// deprecate them (https://go.dev/issue/69573).
package gcexportdata

import (
	"bufio"
	"bytes"
	"encoding/json"
	"fmt"
	"go/token"
	"go/types"
	"io"
	"os/exec"

	"golang.org/x/tools/internal/gcimporter"
)

// Find returns the name of an object (.o) or archive (.a) file
// containing type information for the specified import path,
// using the go command.
// If no file was found, an empty filename is returned.
//
// A relative srcDir is interpreted relative to the current working directory.
//
// Find also returns the package's resolved (canonical) import path,
// reflecting the effects of srcDir and vendoring on importPath.
//
// Deprecated: Use the higher-level API in golang.org/x/tools/go/packages,
// which is more efficient.
func Find(importPath, srcDir string) (filename, path string) {
	cmd := exec.Command("go", "list", "-json", "-export", "--", importPath)
	cmd.Dir = srcDir
	out, err := cmd.Output()
	if err != nil {
		return "", ""
	}
	var data struct {
		ImportPath string
		Export     string
	}
	json.Unmarshal(out, &data)
	return data.Export, data.ImportPath
}

// NewReader returns a reader for the export data section of an object
// (.o) or archive (.a) file read from r.  The new reader may provide
// additional trailing data beyond the end of the export data.
func NewReader(r io.Reader) (io.Reader, error) {
	buf := bufio.NewReader(r)
	size, err := gcimporter.FindExportData(buf)
	if err != nil {
		return nil, err
	}

	// We were given an archive and found the __.PKGDEF in it.
	// This tells us the size of the export data, and we don't
	// need to return the entire file.
	return &io.LimitedReader{
		R: buf,
		N: size,
	}, nil
}

// readAll works the same way as io.ReadAll, but avoids allocations and copies
// by preallocating a byte slice of the necessary size if the size is known up
// front. This is always possible when the input is an archive. In that case,
// NewReader will return the known size using an io.LimitedReader.
func readAll(r io.Reader) ([]byte, error) {
	if lr, ok := r.(*io.LimitedReader); ok {
		data := make([]byte, lr.N)
		_, err := io.ReadFull(lr, data)
		return data, err
	}
	return io.ReadAll(r)
}

// Read reads export data from in, decodes it, and returns type
// information for the package.
//
// Read is capable of reading export data produced by [Write] at the
// same source code version, or by the last two Go releases (plus tip)
// of the standard Go compiler. Reading files from older compilers may
// produce an error.
//
// The package path (effectively its linker symbol prefix) is
// specified by path, since unlike the package name, this information
// may not be recorded in the export data.
//
// File position information is added to fset.
//
// Read may inspect and add to the imports map to ensure that references
// within the export data to other packages are consistent.  The caller
// must ensure that imports[path] does not exist, or exists but is
// incomplete (see types.Package.Complete), and Read inserts the
// resulting package into this map entry.
//
// On return, the state of the reader is undefined.
func Read(in io.Reader, fset *token.FileSet, imports map[string]*types.Package, path string) (*types.Package, error) {
	data, err := readAll(in)
	if err != nil {
		return nil, fmt.Errorf("reading export data for %q: %v", path, err)
	}

	if bytes.HasPrefix(data, []byte("!<arch>")) {
		return nil, fmt.Errorf("can't read export data for %q directly from an archive file (call gcexportdata.NewReader first to extract export data)", path)
	}

	// The indexed export format starts with an 'i'; the older
	// binary export format starts with a 'c', 'd', or 'v'
	// (from "version"). Select appropriate importer.
	if len(data) > 0 {
		switch data[0] {
		case 'v', 'c', 'd':
			// binary, produced by cmd/compile till go1.10
			return nil, fmt.Errorf("binary (%c) import format is no longer supported", data[0])

		case 'i':
			// indexed, produced by cmd/compile till go1.19,
			// and also by [Write].
			//
			// If proposal #69491 is accepted, go/types
			// serialization will be implemented by
			// types.Export, to which Write would eventually
			// delegate (explicitly dropping any pretence at
			// inter-version Write-Read compatibility).
			// This [Read] function would delegate to types.Import
			// when it detects that the file was produced by Export.
			_, pkg, err := gcimporter.IImportData(fset, imports, data[1:], path)
			return pkg, err

		case 'u':
			// unified, produced by cmd/compile since go1.20
			_, pkg, err := gcimporter.UImportData(fset, imports, data[1:], path)
			return pkg, err

		default:
			l := min(len(data), 10)
			return nil, fmt.Errorf("unexpected export data with prefix %q for path %s", string(data[:l]), path)
		}
	}
	return nil, fmt.Errorf("empty export data for %s", path)
}

// Write writes encoded type information for the specified package to out.
// The FileSet provides file position information for named objects.
func Write(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
	if _, err := io.WriteString(out, "i"); err != nil {
		return err
	}
	return gcimporter.IExportData(out, fset, pkg)
}

// ReadBundle reads an export bundle from in, decodes it, and returns type
// information for the packages.
// File position information is added to fset.
//
// ReadBundle may inspect and add to the imports map to ensure that references
// within the export bundle to other packages are consistent.
//
// On return, the state of the reader is undefined.
//
// Experimental: This API is experimental and may change in the future.
func ReadBundle(in io.Reader, fset *token.FileSet, imports map[string]*types.Package) ([]*types.Package, error) {
	data, err := readAll(in)
	if err != nil {
		return nil, fmt.Errorf("reading export bundle: %v", err)
	}
	return gcimporter.IImportBundle(fset, imports, data)
}

// WriteBundle writes encoded type information for the specified packages to out.
// The FileSet provides file position information for named objects.
//
// Experimental: This API is experimental and may change in the future.
func WriteBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error {
	return gcimporter.IExportBundle(out, fset, pkgs)
}


================================================
FILE: go/gcexportdata/importer.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcexportdata

import (
	"fmt"
	"go/token"
	"go/types"
	"os"
)

// NewImporter returns a new instance of the types.Importer interface
// that reads type information from export data files written by gc.
// The Importer also satisfies types.ImporterFrom.
//
// Export data files are located using "go build" workspace conventions
// and the build.Default context.
//
// Use this importer instead of go/importer.For("gc", ...) to avoid the
// version-skew problems described in the documentation of this package,
// or to control the FileSet or access the imports map populated during
// package loading.
//
// Deprecated: Use the higher-level API in golang.org/x/tools/go/packages,
// which is more efficient.
func NewImporter(fset *token.FileSet, imports map[string]*types.Package) types.ImporterFrom {
	return importer{fset, imports}
}

type importer struct {
	fset    *token.FileSet
	imports map[string]*types.Package
}

func (imp importer) Import(importPath string) (*types.Package, error) {
	return imp.ImportFrom(importPath, "", 0)
}

func (imp importer) ImportFrom(importPath, srcDir string, mode types.ImportMode) (_ *types.Package, err error) {
	filename, path := Find(importPath, srcDir)
	if filename == "" {
		if importPath == "unsafe" {
			// Even for unsafe, call Find first in case
			// the package was vendored.
			return types.Unsafe, nil
		}
		return nil, fmt.Errorf("can't find import: %s", importPath)
	}

	if pkg, ok := imp.imports[path]; ok && pkg.Complete() {
		return pkg, nil // cache hit
	}

	// open file
	f, err := os.Open(filename)
	if err != nil {
		return nil, err
	}
	defer func() {
		f.Close()
		if err != nil {
			// add file name to error
			err = fmt.Errorf("reading export data: %s: %v", filename, err)
		}
	}()

	r, err := NewReader(f)
	if err != nil {
		return nil, err
	}

	return Read(r, imp.fset, imp.imports, path)
}


================================================
FILE: go/gcexportdata/main.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The gcexportdata command is a diagnostic tool that displays the
// contents of gc export data files.
package main

import (
	"flag"
	"fmt"
	"go/token"
	"go/types"
	"log"
	"os"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/types/typeutil"
)

var packageFlag = flag.String("package", "", "alternative package to print")

func main() {
	log.SetPrefix("gcexportdata: ")
	log.SetFlags(0)
	flag.Usage = func() {
		fmt.Fprintln(os.Stderr, "usage: gcexportdata [-package path] file.a")
	}
	flag.Parse()
	if flag.NArg() != 1 {
		flag.Usage()
		os.Exit(2)
	}
	filename := flag.Args()[0]

	f, err := os.Open(filename)
	if err != nil {
		log.Fatal(err)
	}

	r, err := gcexportdata.NewReader(f)
	if err != nil {
		log.Fatalf("%s: %s", filename, err)
	}

	// Decode the package.
	const primary = "<primary>"
	imports := make(map[string]*types.Package)
	fset := token.NewFileSet()
	pkg, err := gcexportdata.Read(r, fset, imports, primary)
	if err != nil {
		log.Fatalf("%s: %s", filename, err)
	}

	// Optionally select an indirectly mentioned package.
	if *packageFlag != "" {
		pkg = imports[*packageFlag]
		if pkg == nil {
			fmt.Fprintf(os.Stderr, "export data file %s does not mention %s; has:\n",
				filename, *packageFlag)
			for p := range imports {
				if p != primary {
					fmt.Fprintf(os.Stderr, "\t%s\n", p)
				}
			}
			os.Exit(1)
		}
	}

	// Print all package-level declarations, including non-exported ones.
	fmt.Printf("package %s\n", pkg.Name())
	for _, imp := range pkg.Imports() {
		fmt.Printf("import %q\n", imp.Path())
	}
	qual := func(p *types.Package) string {
		if pkg == p {
			return ""
		}
		return p.Name()
	}
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		fmt.Printf("%s: %s\n",
			fset.Position(obj.Pos()),
			types.ObjectString(obj, qual))

		// For types, print each method.
		if _, ok := obj.(*types.TypeName); ok {
			for _, method := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
				fmt.Printf("%s: %s\n",
					fset.Position(method.Obj().Pos()),
					types.SelectionString(method, qual))
			}
		}
	}
}


================================================
FILE: go/internal/cgo/cgo.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cgo handles cgo preprocessing of files containing `import "C"`.
//
// DESIGN
//
// The approach taken is to run the cgo processor on the package's
// CgoFiles and parse the output, faking the filenames of the
// resulting ASTs so that the synthetic file containing the C types is
// called "C" (e.g. "~/go/src/net/C") and the preprocessed files
// have their original names (e.g. "~/go/src/net/cgo_unix.go"),
// not the names of the actual temporary files.
//
// The advantage of this approach is its fidelity to 'go build'.  The
// downside is that the token.Position.Offset for each AST node is
// incorrect, being an offset within the temporary file.  Line numbers
// should still be correct because of the //line comments.
//
// The logic of this file is mostly plundered from the 'go build'
// tool, which also invokes the cgo preprocessor.
//
//
// REJECTED ALTERNATIVE
//
// An alternative approach that we explored is to extend go/types'
// Importer mechanism to provide the identity of the importing package
// so that each time `import "C"` appears it resolves to a different
// synthetic package containing just the objects needed in that case.
// The loader would invoke cgo but parse only the cgo_types.go file
// defining the package-level objects, discarding the other files
// resulting from preprocessing.
//
// The benefit of this approach would have been that source-level
// syntax information would correspond exactly to the original cgo
// file, with no preprocessing involved, making source tools like
// godoc, guru, and eg happy.  However, the approach was rejected
// due to the additional complexity it would impose on go/types.  (It
// made for a beautiful demo, though.)
//
// cgo files, despite their *.go extension, are not legal Go source
// files per the specification since they may refer to unexported
// members of package "C" such as C.int.  Also, a function such as
// C.getpwent has in effect two types, one matching its C type and one
// which additionally returns (errno C.int).  The cgo preprocessor
// uses name mangling to distinguish these two functions in the
// processed code, but go/types would need to duplicate this logic in
// its handling of function calls, analogous to the treatment of map
// lookups in which y=m[k] and y,ok=m[k] are both legal.

package cgo

import (
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
)

// ProcessFiles invokes the cgo preprocessor on bp.CgoFiles, parses
// the output and returns the resulting ASTs.
func ProcessFiles(bp *build.Package, fset *token.FileSet, DisplayPath func(path string) string, mode parser.Mode) ([]*ast.File, error) {
	tmpdir, err := os.MkdirTemp("", strings.Replace(bp.ImportPath, "/", "_", -1)+"_C")
	if err != nil {
		return nil, err
	}
	defer os.RemoveAll(tmpdir)

	pkgdir := bp.Dir
	if DisplayPath != nil {
		pkgdir = DisplayPath(pkgdir)
	}

	cgoFiles, cgoDisplayFiles, err := Run(bp, pkgdir, tmpdir, false)
	if err != nil {
		return nil, err
	}
	var files []*ast.File
	for i := range cgoFiles {
		rd, err := os.Open(cgoFiles[i])
		if err != nil {
			return nil, err
		}
		display := filepath.Join(bp.Dir, cgoDisplayFiles[i])
		f, err := parser.ParseFile(fset, display, rd, mode)
		rd.Close()
		if err != nil {
			return nil, err
		}
		files = append(files, f)
	}
	return files, nil
}

var cgoRe = regexp.MustCompile(`[/\\:]`)

// Run invokes the cgo preprocessor on bp.CgoFiles and returns two
// lists of files: the resulting processed files (in temporary
// directory tmpdir) and the corresponding names of the unprocessed files.
//
// Run is adapted from (*builder).cgo in
// $GOROOT/src/cmd/go/build.go, but these features are unsupported:
// Objective C, CGOPKGPATH, CGO_FLAGS.
//
// If useabs is set to true, absolute paths of the bp.CgoFiles will be passed in
// to the cgo preprocessor. This in turn will set the // line comments
// referring to those files to use absolute paths. This is needed for
// go/packages using the legacy go list support so it is able to find
// the original files.
func Run(bp *build.Package, pkgdir, tmpdir string, useabs bool) (files, displayFiles []string, err error) {
	cgoCPPFLAGS, _, _, _ := cflags(bp, true)
	_, cgoexeCFLAGS, _, _ := cflags(bp, false)

	if len(bp.CgoPkgConfig) > 0 {
		pcCFLAGS, err := pkgConfigFlags(bp)
		if err != nil {
			return nil, nil, err
		}
		cgoCPPFLAGS = append(cgoCPPFLAGS, pcCFLAGS...)
	}

	// Allows including _cgo_export.h from .[ch] files in the package.
	cgoCPPFLAGS = append(cgoCPPFLAGS, "-I", tmpdir)

	// _cgo_gotypes.go (displayed "C") contains the type definitions.
	files = append(files, filepath.Join(tmpdir, "_cgo_gotypes.go"))
	displayFiles = append(displayFiles, "C")
	for _, fn := range bp.CgoFiles {
		// "foo.cgo1.go" (displayed "foo.go") is the processed Go source.
		f := cgoRe.ReplaceAllString(fn[:len(fn)-len("go")], "_")
		files = append(files, filepath.Join(tmpdir, f+"cgo1.go"))
		displayFiles = append(displayFiles, fn)
	}

	var cgoflags []string
	if bp.Goroot && bp.ImportPath == "runtime/cgo" {
		cgoflags = append(cgoflags, "-import_runtime_cgo=false")
	}
	if bp.Goroot && bp.ImportPath == "runtime/race" || bp.ImportPath == "runtime/cgo" {
		cgoflags = append(cgoflags, "-import_syscall=false")
	}

	var cgoFiles []string = bp.CgoFiles
	if useabs {
		cgoFiles = make([]string, len(bp.CgoFiles))
		for i := range cgoFiles {
			cgoFiles[i] = filepath.Join(pkgdir, bp.CgoFiles[i])
		}
	}

	args := stringList(
		"go", "tool", "cgo", "-objdir", tmpdir, cgoflags, "--",
		cgoCPPFLAGS, cgoexeCFLAGS, cgoFiles,
	)
	if false {
		log.Printf("Running cgo for package %q: %s (dir=%s)", bp.ImportPath, args, pkgdir)
	}
	cmd := exec.Command(args[0], args[1:]...)
	cmd.Dir = pkgdir
	cmd.Env = append(os.Environ(), "PWD="+pkgdir)
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		return nil, nil, fmt.Errorf("cgo failed: %s: %s", args, err)
	}

	return files, displayFiles, nil
}

// -- unmodified from 'go build' ---------------------------------------

// Return the flags to use when invoking the C or C++ compilers, or cgo.
func cflags(p *build.Package, def bool) (cppflags, cflags, cxxflags, ldflags []string) {
	var defaults string
	if def {
		defaults = "-g -O2"
	}

	cppflags = stringList(envList("CGO_CPPFLAGS", ""), p.CgoCPPFLAGS)
	cflags = stringList(envList("CGO_CFLAGS", defaults), p.CgoCFLAGS)
	cxxflags = stringList(envList("CGO_CXXFLAGS", defaults), p.CgoCXXFLAGS)
	ldflags = stringList(envList("CGO_LDFLAGS", defaults), p.CgoLDFLAGS)
	return
}

// envList returns the value of the given environment variable broken
// into fields, using the default value when the variable is empty.
func envList(key, def string) []string {
	v := os.Getenv(key)
	if v == "" {
		v = def
	}
	return strings.Fields(v)
}

// stringList's arguments should be a sequence of string or []string values.
// stringList flattens them into a single []string.
func stringList(args ...any) []string {
	var x []string
	for _, arg := range args {
		switch arg := arg.(type) {
		case []string:
			x = append(x, arg...)
		case string:
			x = append(x, arg)
		default:
			panic("stringList: invalid argument")
		}
	}
	return x
}


================================================
FILE: go/internal/cgo/cgo_pkgconfig.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cgo

import (
	"errors"
	"fmt"
	"go/build"
	"os/exec"
	"strings"
)

// pkgConfig runs pkg-config with the specified arguments and returns the flags it prints.
func pkgConfig(mode string, pkgs []string) (flags []string, err error) {
	cmd := exec.Command("pkg-config", append([]string{mode}, pkgs...)...)
	out, err := cmd.Output()
	if err != nil {
		s := fmt.Sprintf("%s failed: %v", strings.Join(cmd.Args, " "), err)
		if len(out) > 0 {
			s = fmt.Sprintf("%s: %s", s, out)
		}
		if err, ok := err.(*exec.ExitError); ok && len(err.Stderr) > 0 {
			s = fmt.Sprintf("%s\nstderr:\n%s", s, err.Stderr)
		}
		return nil, errors.New(s)
	}
	if len(out) > 0 {
		flags = strings.Fields(string(out))
	}
	return
}

// pkgConfigFlags calls pkg-config if needed and returns the cflags
// needed to build the package.
func pkgConfigFlags(p *build.Package) (cflags []string, err error) {
	if len(p.CgoPkgConfig) == 0 {
		return nil, nil
	}
	return pkgConfig("--cflags", p.CgoPkgConfig)
}


================================================
FILE: go/internal/gccgoimporter/ar.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter.

package gccgoimporter

import (
	"bytes"
	"debug/elf"
	"errors"
	"fmt"
	"io"
	"strconv"
	"strings"
)

// Magic strings for different archive file formats.
const (
	armag  = "!<arch>\n"
	armagt = "!<thin>\n"
	armagb = "<bigaf>\n"
)

// Offsets and sizes for fields in a standard archive header.
const (
	arNameOff  = 0
	arNameSize = 16
	arDateOff  = arNameOff + arNameSize
	arDateSize = 12
	arUIDOff   = arDateOff + arDateSize
	arUIDSize  = 6
	arGIDOff   = arUIDOff + arUIDSize
	arGIDSize  = 6
	arModeOff  = arGIDOff + arGIDSize
	arModeSize = 8
	arSizeOff  = arModeOff + arModeSize
	arSizeSize = 10
	arFmagOff  = arSizeOff + arSizeSize
	arFmagSize = 2

	arHdrSize = arFmagOff + arFmagSize
)

// The contents of the fmag field of a standard archive header.
const arfmag = "`\n"

// arExportData takes an archive file and returns a ReadSeeker for the
// export data in that file. This assumes that there is only one
// object in the archive containing export data, which is not quite
// what gccgo does; gccgo concatenates together all the export data
// for all the objects in the file.  In practice that case does not arise.
func arExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
	if _, err := archive.Seek(0, io.SeekStart); err != nil {
		return nil, err
	}

	var buf [len(armag)]byte
	if _, err := archive.Read(buf[:]); err != nil {
		return nil, err
	}

	switch string(buf[:]) {
	case armag:
		return standardArExportData(archive)
	case armagt:
		return nil, errors.New("unsupported thin archive")
	case armagb:
		return nil, errors.New("unsupported AIX big archive")
	default:
		return nil, fmt.Errorf("unrecognized archive file format %q", buf[:])
	}
}

// standardArExportData returns export data form a standard archive.
func standardArExportData(archive io.ReadSeeker) (io.ReadSeeker, error) {
	off := int64(len(armag))
	for {
		var hdrBuf [arHdrSize]byte
		if _, err := archive.Read(hdrBuf[:]); err != nil {
			return nil, err
		}
		off += arHdrSize

		if !bytes.Equal(hdrBuf[arFmagOff:arFmagOff+arFmagSize], []byte(arfmag)) {
			return nil, fmt.Errorf("archive header format header (%q)", hdrBuf[:])
		}

		size, err := strconv.ParseInt(strings.TrimSpace(string(hdrBuf[arSizeOff:arSizeOff+arSizeSize])), 10, 64)
		if err != nil {
			return nil, fmt.Errorf("error parsing size in archive header (%q): %v", hdrBuf[:], err)
		}

		fn := hdrBuf[arNameOff : arNameOff+arNameSize]
		if fn[0] == '/' && (fn[1] == ' ' || fn[1] == '/' || bytes.Equal(fn[:8], []byte("/SYM64/ "))) {
			// Archive symbol table or extended name table,
			// which we don't care about.
		} else {
			archiveAt := readerAtFromSeeker(archive)
			ret, err := elfFromAr(io.NewSectionReader(archiveAt, off, size))
			if ret != nil || err != nil {
				return ret, err
			}
		}

		if size&1 != 0 {
			size++
		}
		off += size
		if _, err := archive.Seek(off, io.SeekStart); err != nil {
			return nil, err
		}
	}
}

// elfFromAr tries to get export data from an archive member as an ELF file.
// If there is no export data, this returns nil, nil.
func elfFromAr(member *io.SectionReader) (io.ReadSeeker, error) {
	ef, err := elf.NewFile(member)
	if err != nil {
		return nil, err
	}
	sec := ef.Section(".go_export")
	if sec == nil {
		return nil, nil
	}
	return sec.Open(), nil
}

// readerAtFromSeeker turns an io.ReadSeeker into an io.ReaderAt.
// This is only safe because there won't be any concurrent seeks
// while this code is executing.
func readerAtFromSeeker(rs io.ReadSeeker) io.ReaderAt {
	if ret, ok := rs.(io.ReaderAt); ok {
		return ret
	}
	return seekerReadAt{rs}
}

type seekerReadAt struct {
	seeker io.ReadSeeker
}

func (sra seekerReadAt) ReadAt(p []byte, off int64) (int, error) {
	if _, err := sra.seeker.Seek(off, io.SeekStart); err != nil {
		return 0, err
	}
	return sra.seeker.Read(p)
}


================================================
FILE: go/internal/gccgoimporter/backdoor.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file opens a back door to the parser for golang.org/x/tools/go/gccgoexportdata.

package gccgoimporter

import (
	"go/types"
	"io"
)

// Parse reads and parses gccgo export data from in and constructs a
// Package, inserting it into the imports map.
func Parse(in io.Reader, imports map[string]*types.Package, path string) (_ *types.Package, err error) {
	var p parser
	p.init(path, in, imports)
	defer func() {
		switch x := recover().(type) {
		case nil:
			// success
		case importError:
			err = x
		default:
			panic(x) // resume unexpected panic
		}
	}()
	pkg := p.parsePackage()
	imports[path] = pkg
	return pkg, err
}


================================================
FILE: go/internal/gccgoimporter/gccgoinstallation.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter.

package gccgoimporter

import (
	"bufio"
	"go/types"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

// Information about a specific installation of gccgo.
type GccgoInstallation struct {
	// Version of gcc (e.g. 4.8.0).
	GccVersion string

	// Target triple (e.g. x86_64-unknown-linux-gnu).
	TargetTriple string

	// Built-in library paths used by this installation.
	LibPaths []string
}

// Ask the driver at the given path for information for this GccgoInstallation.
// The given arguments are passed directly to the call of the driver.
func (inst *GccgoInstallation) InitFromDriver(gccgoPath string, args ...string) (err error) {
	argv := append([]string{"-###", "-S", "-x", "go", "-"}, args...)
	cmd := exec.Command(gccgoPath, argv...)
	stderr, err := cmd.StderrPipe()
	if err != nil {
		return
	}

	err = cmd.Start()
	if err != nil {
		return
	}

	scanner := bufio.NewScanner(stderr)
	for scanner.Scan() {
		line := scanner.Text()
		switch {
		case strings.HasPrefix(line, "Target: "):
			inst.TargetTriple = line[8:]

		case line[0] == ' ':
			args := strings.Fields(line)
			for _, arg := range args[1:] {
				if strings.HasPrefix(arg, "-L") {
					inst.LibPaths = append(inst.LibPaths, arg[2:])
				}
			}
		}
	}

	argv = append([]string{"-dumpversion"}, args...)
	stdout, err := exec.Command(gccgoPath, argv...).Output()
	if err != nil {
		return
	}
	inst.GccVersion = strings.TrimSpace(string(stdout))

	return
}

// Return the list of export search paths for this GccgoInstallation.
func (inst *GccgoInstallation) SearchPaths() (paths []string) {
	for _, lpath := range inst.LibPaths {
		spath := filepath.Join(lpath, "go", inst.GccVersion)
		fi, err := os.Stat(spath)
		if err != nil || !fi.IsDir() {
			continue
		}
		paths = append(paths, spath)

		spath = filepath.Join(spath, inst.TargetTriple)
		fi, err = os.Stat(spath)
		if err != nil || !fi.IsDir() {
			continue
		}
		paths = append(paths, spath)
	}

	paths = append(paths, inst.LibPaths...)

	return
}

// Return an importer that searches incpaths followed by the gcc installation's
// built-in search paths and the current directory.
func (inst *GccgoInstallation) GetImporter(incpaths []string, initmap map[*types.Package]InitData) Importer {
	return GetImporter(append(append(incpaths, inst.SearchPaths()...), "."), initmap)
}


================================================
FILE: go/internal/gccgoimporter/gccgoinstallation_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter.

package gccgoimporter

import (
	"go/types"
	"runtime"
	"testing"
)

// importablePackages is a list of packages that we verify that we can
// import. This should be all standard library packages in all relevant
// versions of gccgo. Note that since gccgo follows a different release
// cycle, and since different systems have different versions installed,
// we can't use the last-two-versions rule of the gc toolchain.
var importablePackages = [...]string{
	"archive/tar",
	"archive/zip",
	"bufio",
	"bytes",
	"compress/bzip2",
	"compress/flate",
	"compress/gzip",
	"compress/lzw",
	"compress/zlib",
	"container/heap",
	"container/list",
	"container/ring",
	"crypto/aes",
	"crypto/cipher",
	"crypto/des",
	"crypto/dsa",
	"crypto/ecdsa",
	"crypto/elliptic",
	"crypto",
	"crypto/hmac",
	"crypto/md5",
	"crypto/rand",
	"crypto/rc4",
	"crypto/rsa",
	"crypto/sha1",
	"crypto/sha256",
	"crypto/sha512",
	"crypto/subtle",
	"crypto/tls",
	"crypto/x509",
	"crypto/x509/pkix",
	"database/sql/driver",
	"database/sql",
	"debug/dwarf",
	"debug/elf",
	"debug/gosym",
	"debug/macho",
	"debug/pe",
	"encoding/ascii85",
	"encoding/asn1",
	"encoding/base32",
	"encoding/base64",
	"encoding/binary",
	"encoding/csv",
	"encoding/gob",
	// "encoding", // Added in GCC 4.9.
	"encoding/hex",
	"encoding/json",
	"encoding/pem",
	"encoding/xml",
	"errors",
	"expvar",
	"flag",
	"fmt",
	"go/ast",
	"go/build",
	"go/doc",
	// "go/format", // Added in GCC 4.8.
	"go/parser",
	"go/printer",
	"go/scanner",
	"go/token",
	"hash/adler32",
	"hash/crc32",
	"hash/crc64",
	"hash/fnv",
	"hash",
	"html",
	"html/template",
	"image/color",
	// "image/color/palette", // Added in GCC 4.9.
	"image/draw",
	"image/gif",
	"image",
	"image/jpeg",
	"image/png",
	"index/suffixarray",
	"io",
	"io/ioutil",
	"log",
	"log/syslog",
	"math/big",
	"math/cmplx",
	"math",
	"math/rand",
	"mime",
	"mime/multipart",
	"net",
	"net/http/cgi",
	// "net/http/cookiejar", // Added in GCC 4.8.
	"net/http/fcgi",
	"net/http",
	"net/http/httptest",
	"net/http/httputil",
	"net/http/pprof",
	"net/mail",
	"net/rpc",
	"net/rpc/jsonrpc",
	"net/smtp",
	"net/textproto",
	"net/url",
	"os/exec",
	"os",
	"os/signal",
	"os/user",
	"path/filepath",
	"path",
	"reflect",
	"regexp",
	"regexp/syntax",
	"runtime/debug",
	"runtime",
	"runtime/pprof",
	"sort",
	"strconv",
	"strings",
	"sync/atomic",
	"sync",
	"syscall",
	"testing",
	"testing/iotest",
	"testing/quick",
	"text/scanner",
	"text/tabwriter",
	"text/template",
	"text/template/parse",
	"time",
	"unicode",
	"unicode/utf16",
	"unicode/utf8",
}

func TestInstallationImporter(t *testing.T) {
	// This test relies on gccgo being around.
	gpath := gccgoPath()
	if gpath == "" {
		t.Skip("This test needs gccgo")
	}
	if runtime.GOOS == "aix" {
		// We don't yet have a debug/xcoff package for reading
		// object files on AIX. Remove this skip if/when issue #29038
		// is implemented (see also issue #49445).
		t.Skip("no support yet for debug/xcoff")
	}

	var inst GccgoInstallation
	err := inst.InitFromDriver(gpath)
	if err != nil {
		t.Fatal(err)
	}
	imp := inst.GetImporter(nil, nil)

	// Ensure we don't regress the number of packages we can parse. First import
	// all packages into the same map and then each individually.
	pkgMap := make(map[string]*types.Package)
	for _, pkg := range importablePackages {
		_, err = imp(pkgMap, pkg, ".", nil)
		if err != nil {
			t.Error(err)
		}
	}

	for _, pkg := range importablePackages {
		_, err = imp(make(map[string]*types.Package), pkg, ".", nil)
		if err != nil {
			t.Error(err)
		}
	}

	// Test for certain specific entities in the imported data.
	for _, test := range [...]importerTest{
		{pkgpath: "io", name: "Reader", want: "type Reader interface{Read(p []byte) (n int, err error)}"},
		{pkgpath: "io", name: "ReadWriter", want: "type ReadWriter interface{Reader; Writer}"},
		{pkgpath: "math", name: "Pi", want: "const Pi untyped float"},
		{pkgpath: "math", name: "Sin", want: "func Sin(x float64) float64"},
		{pkgpath: "sort", name: "Search", want: "func Search(n int, f func(int) bool) int"},
		{pkgpath: "unsafe", name: "Pointer", want: "type Pointer"},
	} {
		runImporterTest(t, imp, nil, &test)
	}
}


================================================
FILE: go/internal/gccgoimporter/importer.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment and the import path, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter.

// Package gccgoimporter implements Import for gccgo-generated object files.
package gccgoimporter // import "golang.org/x/tools/go/internal/gccgoimporter"

import (
	"debug/elf"
	"fmt"
	"go/types"
	"io"
	"os"
	"path/filepath"
	"strings"
)

// A PackageInit describes an imported package that needs initialization.
type PackageInit struct {
	Name     string // short package name
	InitFunc string // name of init function
	Priority int    // priority of init function, see InitData.Priority
}

// The gccgo-specific init data for a package.
type InitData struct {
	// Initialization priority of this package relative to other packages.
	// This is based on the maximum depth of the package's dependency graph;
	// it is guaranteed to be greater than that of its dependencies.
	Priority int

	// The list of packages which this package depends on to be initialized,
	// including itself if needed. This is the subset of the transitive closure of
	// the package's dependencies that need initialization.
	Inits []PackageInit
}

// Locate the file from which to read export data.
// This is intended to replicate the logic in gofrontend.
func findExportFile(searchpaths []string, pkgpath string) (string, error) {
	for _, spath := range searchpaths {
		pkgfullpath := filepath.Join(spath, pkgpath)
		pkgdir, name := filepath.Split(pkgfullpath)

		for _, filepath := range [...]string{
			pkgfullpath,
			pkgfullpath + ".gox",
			pkgdir + "lib" + name + ".so",
			pkgdir + "lib" + name + ".a",
			pkgfullpath + ".o",
		} {
			fi, err := os.Stat(filepath)
			if err == nil && !fi.IsDir() {
				return filepath, nil
			}
		}
	}

	return "", fmt.Errorf("%s: could not find export data (tried %s)", pkgpath, strings.Join(searchpaths, ":"))
}

const (
	gccgov1Magic    = "v1;\n"
	gccgov2Magic    = "v2;\n"
	gccgov3Magic    = "v3;\n"
	goimporterMagic = "\n$$ "
	archiveMagic    = "!<ar"
)

// Opens the export data file at the given path. If this is an ELF file,
// searches for and opens the .go_export section. If this is an archive,
// reads the export data from the first member, which is assumed to be an ELF file.
// This is intended to replicate the logic in gofrontend.
func openExportFile(fpath string) (reader io.ReadSeeker, closer io.Closer, err error) {
	f, err := os.Open(fpath)
	if err != nil {
		return
	}
	closer = f
	defer func() {
		if err != nil && closer != nil {
			f.Close()
		}
	}()

	var magic [4]byte
	_, err = f.ReadAt(magic[:], 0)
	if err != nil {
		return
	}

	var elfreader io.ReaderAt
	switch string(magic[:]) {
	case gccgov1Magic, gccgov2Magic, gccgov3Magic, goimporterMagic:
		// Raw export data.
		reader = f
		return

	case archiveMagic:
		reader, err = arExportData(f)
		return

	default:
		elfreader = f
	}

	ef, err := elf.NewFile(elfreader)
	if err != nil {
		return
	}

	sec := ef.Section(".go_export")
	if sec == nil {
		err = fmt.Errorf("%s: .go_export section not found", fpath)
		return
	}

	reader = sec.Open()
	return
}

// An Importer resolves import paths to Packages. The imports map records
// packages already known, indexed by package path.
// An importer must determine the canonical package path and check imports
// to see if it is already present in the map. If so, the Importer can return
// the map entry. Otherwise, the importer must load the package data for the
// given path into a new *Package, record it in imports map, and return the
// package.
type Importer func(imports map[string]*types.Package, path, srcDir string, lookup func(string) (io.ReadCloser, error)) (*types.Package, error)

func GetImporter(searchpaths []string, initmap map[*types.Package]InitData) Importer {
	return func(imports map[string]*types.Package, pkgpath, srcDir string, lookup func(string) (io.ReadCloser, error)) (pkg *types.Package, err error) {
		// TODO(gri): Use srcDir.
		// Or not. It's possible that srcDir will fade in importance as
		// the go command and other tools provide a translation table
		// for relative imports (like ./foo or vendored imports).
		if pkgpath == "unsafe" {
			return types.Unsafe, nil
		}

		var reader io.ReadSeeker
		var fpath string
		var rc io.ReadCloser
		if lookup != nil {
			if p := imports[pkgpath]; p != nil && p.Complete() {
				return p, nil
			}
			rc, err = lookup(pkgpath)
			if err != nil {
				return nil, err
			}
		}
		if rc != nil {
			defer rc.Close()
			rs, ok := rc.(io.ReadSeeker)
			if !ok {
				return nil, fmt.Errorf("gccgo importer requires lookup to return an io.ReadSeeker, have %T", rc)
			}
			reader = rs
			fpath = "<lookup " + pkgpath + ">"
			// Take name from Name method (like on os.File) if present.
			if n, ok := rc.(interface{ Name() string }); ok {
				fpath = n.Name()
			}
		} else {
			fpath, err = findExportFile(searchpaths, pkgpath)
			if err != nil {
				return nil, err
			}

			r, closer, err := openExportFile(fpath)
			if err != nil {
				return nil, err
			}
			if closer != nil {
				defer closer.Close()
			}
			reader = r
		}

		var magics string
		magics, err = readMagic(reader)
		if err != nil {
			return
		}

		if magics == archiveMagic {
			reader, err = arExportData(reader)
			if err != nil {
				return
			}
			magics, err = readMagic(reader)
			if err != nil {
				return
			}
		}

		switch magics {
		case gccgov1Magic, gccgov2Magic, gccgov3Magic:
			var p parser
			p.init(fpath, reader, imports)
			pkg = p.parsePackage()
			if initmap != nil {
				initmap[pkg] = p.initdata
			}

		// Excluded for now: Standard gccgo doesn't support this import format currently.
		// case goimporterMagic:
		// 	var data []byte
		// 	data, err = io.ReadAll(reader)
		// 	if err != nil {
		// 		return
		// 	}
		// 	var n int
		// 	n, pkg, err = importer.ImportData(imports, data)
		// 	if err != nil {
		// 		return
		// 	}

		// 	if initmap != nil {
		// 		suffixreader := bytes.NewReader(data[n:])
		// 		var p parser
		// 		p.init(fpath, suffixreader, nil)
		// 		p.parseInitData()
		// 		initmap[pkg] = p.initdata
		// 	}

		default:
			err = fmt.Errorf("unrecognized magic string: %q", magics)
		}

		return
	}
}

// readMagic reads the four bytes at the start of a ReadSeeker and
// returns them as a string.
func readMagic(reader io.ReadSeeker) (string, error) {
	var magic [4]byte
	if _, err := reader.Read(magic[:]); err != nil {
		return "", err
	}
	if _, err := reader.Seek(0, io.SeekStart); err != nil {
		return "", err
	}
	return string(magic[:]), nil
}


================================================
FILE: go/internal/gccgoimporter/importer_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter without
// the import of "testenv".

package gccgoimporter

import (
	"go/types"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"testing"
)

type importerTest struct {
	pkgpath, name, want, wantval string
	wantinits                    []string
	gccgoVersion                 int // minimum gccgo version (0 => any)
}

func runImporterTest(t *testing.T, imp Importer, initmap map[*types.Package]InitData, test *importerTest) {
	pkg, err := imp(make(map[string]*types.Package), test.pkgpath, ".", nil)
	if err != nil {
		t.Error(err)
		return
	}

	if test.name != "" {
		obj := pkg.Scope().Lookup(test.name)
		if obj == nil {
			t.Errorf("%s: object not found", test.name)
			return
		}

		got := types.ObjectString(obj, types.RelativeTo(pkg))
		if got != test.want {
			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
		}

		if test.wantval != "" {
			gotval := obj.(*types.Const).Val().String()
			if gotval != test.wantval {
				t.Errorf("%s: got val %q; want val %q", test.name, gotval, test.wantval)
			}
		}
	}

	if len(test.wantinits) > 0 {
		initdata := initmap[pkg]
		found := false
		// Check that the package's own init function has the package's priority
		for _, pkginit := range initdata.Inits {
			if pkginit.InitFunc == test.wantinits[0] {
				found = true
				break
			}
		}

		if !found {
			t.Errorf("%s: could not find expected function %q", test.pkgpath, test.wantinits[0])
		}

		// FIXME: the original version of this test was written against
		// the v1 export data scheme for capturing init functions, so it
		// verified the priority values. We moved away from the priority
		// scheme some time ago; it is not clear how much work it would be
		// to validate the new init export data.
	}
}

// When adding tests to this list, be sure to set the 'gccgoVersion'
// field if the testcases uses a "recent" Go addition (ex: aliases).
var importerTests = [...]importerTest{
	{pkgpath: "pointer", name: "Int8Ptr", want: "type Int8Ptr *int8"},
	{pkgpath: "complexnums", name: "NN", want: "const NN untyped complex", wantval: "(-1 + -1i)"},
	{pkgpath: "complexnums", name: "NP", want: "const NP untyped complex", wantval: "(-1 + 1i)"},
	{pkgpath: "complexnums", name: "PN", want: "const PN untyped complex", wantval: "(1 + -1i)"},
	{pkgpath: "complexnums", name: "PP", want: "const PP untyped complex", wantval: "(1 + 1i)"},
	{pkgpath: "conversions", name: "Bits", want: "const Bits Units", wantval: `"bits"`},
	{pkgpath: "time", name: "Duration", want: "type Duration int64"},
	{pkgpath: "time", name: "Nanosecond", want: "const Nanosecond Duration", wantval: "1"},
	{pkgpath: "unicode", name: "IsUpper", want: "func IsUpper(r rune) bool"},
	{pkgpath: "unicode", name: "MaxRune", want: "const MaxRune untyped rune", wantval: "1114111"},
	{pkgpath: "imports", wantinits: []string{"imports..import", "fmt..import"}},
	{pkgpath: "importsar", name: "Hello", want: "var Hello string"},
	{pkgpath: "aliases", name: "A14", gccgoVersion: 7, want: "type A14 = func(int, T0) chan T2"},
	{pkgpath: "aliases", name: "C0", gccgoVersion: 7, want: "type C0 struct{f1 C1; f2 C1}"},
	{pkgpath: "escapeinfo", name: "NewT", want: "func NewT(data []byte) *T"},
	{pkgpath: "issue27856", name: "M", gccgoVersion: 7, want: "type M struct{E F}"},
	{pkgpath: "v1reflect", name: "Type", want: "type Type interface{Align() int; AssignableTo(u Type) bool; Bits() int; ChanDir() ChanDir; Elem() Type; Field(i int) StructField; FieldAlign() int; FieldByIndex(index []int) StructField; FieldByName(name string) (StructField, bool); FieldByNameFunc(match func(string) bool) (StructField, bool); Implements(u Type) bool; In(i int) Type; IsVariadic() bool; Key() Type; Kind() Kind; Len() int; Method(int) Method; MethodByName(string) (Method, bool); Name() string; NumField() int; NumIn() int; NumMethod() int; NumOut() int; Out(i int) Type; PkgPath() string; Size() uintptr; String() string; common() *commonType; rawString() string; runtimeType() *runtimeType; uncommon() *uncommonType}"},
	{pkgpath: "nointerface", name: "I", want: "type I int"},
	{pkgpath: "issue29198", name: "FooServer", gccgoVersion: 7, want: "type FooServer struct{FooServer *FooServer; user string; ctx context.Context}"},
	{pkgpath: "issue30628", name: "Apple", want: "type Apple struct{hey sync.RWMutex; x int; RQ [517]struct{Count uintptr; NumBytes uintptr; Last uintptr}}"},
	{pkgpath: "issue31540", name: "S", gccgoVersion: 7, want: "type S struct{b int; map[Y]Z}"},
	{pkgpath: "issue34182", name: "T1", want: "type T1 struct{f *T2}"},
	{pkgpath: "notinheap", name: "S", want: "type S struct{}"},
}

func TestGoxImporter(t *testing.T) {
	testenv.MustHaveExec(t) // this is to skip nacl, js
	initmap := make(map[*types.Package]InitData)
	imp := GetImporter([]string{"testdata"}, initmap)

	for _, test := range importerTests {
		runImporterTest(t, imp, initmap, &test)
	}
}

// gccgoPath returns a path to gccgo if it is present (either in
// path or specified via GCCGO environment variable), or an
// empty string if no gccgo is available.
func gccgoPath() string {
	gccgoname := os.Getenv("GCCGO")
	if gccgoname == "" {
		gccgoname = "gccgo"
	}
	if gpath, gerr := exec.LookPath(gccgoname); gerr == nil {
		return gpath
	}
	return ""
}

func TestObjImporter(t *testing.T) {
	// This test relies on gccgo being around.
	gpath := gccgoPath()
	if gpath == "" {
		t.Skip("This test needs gccgo")
	}
	if runtime.GOOS == "aix" {
		// We don't yet have a debug/xcoff package for reading
		// object files on AIX. Remove this skip if/when issue #29038
		// is implemented (see also issue #49445).
		t.Skip("no support yet for debug/xcoff")
	}

	verout, err := exec.Command(gpath, "--version").Output()
	if err != nil {
		t.Logf("%s", verout)
		if exit, ok := err.(*exec.ExitError); ok && len(exit.Stderr) > 0 {
			t.Logf("stderr:\n%s", exit.Stderr)
		}
		t.Fatal(err)
	}
	vers := regexp.MustCompile(`([0-9]+)\.([0-9]+)`).FindSubmatch(verout)
	if len(vers) == 0 {
		t.Fatalf("could not find version number in %s", verout)
	}
	major, err := strconv.Atoi(string(vers[1]))
	if err != nil {
		t.Fatal(err)
	}
	minor, err := strconv.Atoi(string(vers[2]))
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("gccgo version %d.%d", major, minor)

	tmpdir := t.TempDir()
	initmap := make(map[*types.Package]InitData)
	imp := GetImporter([]string{tmpdir}, initmap)

	artmpdir := t.TempDir()
	arinitmap := make(map[*types.Package]InitData)
	arimp := GetImporter([]string{artmpdir}, arinitmap)

	for _, test := range importerTests {
		if major < test.gccgoVersion {
			// Support for type aliases was added in GCC 7.
			t.Logf("skipping %q: not supported before gccgo version %d", test.pkgpath, test.gccgoVersion)
			continue
		}

		gofile := filepath.Join("testdata", test.pkgpath+".go")
		if _, err := os.Stat(gofile); os.IsNotExist(err) {
			continue
		}
		ofile := filepath.Join(tmpdir, test.pkgpath+".o")
		afile := filepath.Join(artmpdir, "lib"+test.pkgpath+".a")

		cmd := exec.Command(gpath, "-fgo-pkgpath="+test.pkgpath, "-c", "-o", ofile, gofile)
		if out, err := cmd.CombinedOutput(); err != nil {
			t.Logf("%s", out)
			t.Fatalf("gccgo %s failed: %s", gofile, err)
		}

		runImporterTest(t, imp, initmap, &test)

		cmd = exec.Command("ar", "cr", afile, ofile)
		if out, err := cmd.CombinedOutput(); err != nil {
			t.Logf("%s", out)
			t.Fatalf("ar cr %s %s failed: %s", afile, ofile, err)
		}

		runImporterTest(t, arimp, arinitmap, &test)

		if err = os.Remove(ofile); err != nil {
			t.Fatal(err)
		}
		if err = os.Remove(afile); err != nil {
			t.Fatal(err)
		}
	}
}


================================================
FILE: go/internal/gccgoimporter/newInterface10.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.11

package gccgoimporter

import "go/types"

func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
	named := make([]*types.Named, len(embeddeds))
	for i, e := range embeddeds {
		var ok bool
		named[i], ok = e.(*types.Named)
		if !ok {
			panic("embedding of non-defined interfaces in interfaces is not supported before Go 1.11")
		}
	}
	return types.NewInterface(methods, named)
}


================================================
FILE: go/internal/gccgoimporter/newInterface11.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.11

package gccgoimporter

import "go/types"

func newInterface(methods []*types.Func, embeddeds []types.Type) *types.Interface {
	return types.NewInterfaceType(methods, embeddeds)
}


================================================
FILE: go/internal/gccgoimporter/parser.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter, with
// a small modification in parseInterface to support older Go versions.

package gccgoimporter

import (
	"bytes"
	"errors"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"io"
	"strconv"
	"strings"
	"text/scanner"
	"unicode/utf8"

	"golang.org/x/tools/internal/typesinternal"
)

type parser struct {
	scanner  *scanner.Scanner
	version  string                    // format version
	tok      rune                      // current token
	lit      string                    // literal string; only valid for Ident, Int, String tokens
	pkgpath  string                    // package path of imported package
	pkgname  string                    // name of imported package
	pkg      *types.Package            // reference to imported package
	imports  map[string]*types.Package // package path -> package object
	typeList []types.Type              // type number -> type
	typeData []string                  // unparsed type data (v3 and later)
	fixups   []fixupRecord             // fixups to apply at end of parsing
	initdata InitData                  // package init priority data
	aliases  map[int]string            // maps saved type number to alias name
}

// When reading export data it's possible to encounter a defined type
// N1 with an underlying defined type N2 while we are still reading in
// that defined type N2; see issues #29006 and #29198 for instances
// of this. Example:
//
//   type N1 N2
//   type N2 struct {
//      ...
//      p *N1
//   }
//
// To handle such cases, the parser generates a fixup record (below) and
// delays setting of N1's underlying type until parsing is complete, at
// which point fixups are applied.

type fixupRecord struct {
	toUpdate *types.Named // type to modify when fixup is processed
	target   types.Type   // type that was incomplete when fixup was created
}

func (p *parser) init(filename string, src io.Reader, imports map[string]*types.Package) {
	p.scanner = new(scanner.Scanner)
	p.initScanner(filename, src)
	p.imports = imports
	p.aliases = make(map[int]string)
	p.typeList = make([]types.Type, 1 /* type numbers start at 1 */, 16)
}

func (p *parser) initScanner(filename string, src io.Reader) {
	p.scanner.Init(src)
	p.scanner.Error = func(_ *scanner.Scanner, msg string) { p.error(msg) }
	p.scanner.Mode = scanner.ScanIdents | scanner.ScanInts | scanner.ScanFloats | scanner.ScanStrings
	p.scanner.Whitespace = 1<<'\t' | 1<<' '
	p.scanner.Filename = filename // for good error messages
	p.next()
}

type importError struct {
	pos scanner.Position
	err error
}

func (e importError) Error() string {
	return fmt.Sprintf("import error %s (byte offset = %d): %s", e.pos, e.pos.Offset, e.err)
}

func (p *parser) error(err any) {
	if s, ok := err.(string); ok {
		err = errors.New(s)
	}
	// panic with a runtime.Error if err is not an error
	panic(importError{p.scanner.Pos(), err.(error)})
}

func (p *parser) errorf(format string, args ...any) {
	p.error(fmt.Errorf(format, args...))
}

func (p *parser) expect(tok rune) string {
	lit := p.lit
	if p.tok != tok {
		p.errorf("expected %s, got %s (%s)", scanner.TokenString(tok), scanner.TokenString(p.tok), lit)
	}
	p.next()
	return lit
}

func (p *parser) expectEOL() {
	if p.version == "v1" || p.version == "v2" {
		p.expect(';')
	}
	p.expect('\n')
}

func (p *parser) expectKeyword(keyword string) {
	lit := p.expect(scanner.Ident)
	if lit != keyword {
		p.errorf("expected keyword %s, got %q", keyword, lit)
	}
}

func (p *parser) parseString() string {
	str, err := strconv.Unquote(p.expect(scanner.String))
	if err != nil {
		p.error(err)
	}
	return str
}

// parseUnquotedString parses an UnquotedString:
//
//	unquotedString     = { unquotedStringChar } .
//	unquotedStringChar = <neither a whitespace nor a ';' char> .
func (p *parser) parseUnquotedString() string {
	if p.tok == scanner.EOF {
		p.error("unexpected EOF")
	}
	var buf bytes.Buffer
	buf.WriteString(p.scanner.TokenText())
	// This loop needs to examine each character before deciding whether to consume it. If we see a semicolon,
	// we need to let it be consumed by p.next().
	for ch := p.scanner.Peek(); ch != '\n' && ch != ';' && ch != scanner.EOF && p.scanner.Whitespace&(1<<uint(ch)) == 0; ch = p.scanner.Peek() {
		buf.WriteRune(ch)
		p.scanner.Next()
	}
	p.next()
	return buf.String()
}

func (p *parser) next() {
	p.tok = p.scanner.Scan()
	switch p.tok {
	case scanner.Ident, scanner.Int, scanner.Float, scanner.String, '·':
		p.lit = p.scanner.TokenText()
	default:
		p.lit = ""
	}
}

func (p *parser) parseQualifiedName() (path, name string) {
	return p.parseQualifiedNameStr(p.parseString())
}

func (p *parser) parseUnquotedQualifiedName() (path, name string) {
	return p.parseQualifiedNameStr(p.parseUnquotedString())
}

// parseQualifiedNameStr is given the leading name (unquoted by the caller if necessary)
// and then parses the remainder of a qualified name:
//
//	qualifiedName = [ ["."] unquotedString "." ] unquotedString .
//
// The above production uses greedy matching.
func (p *parser) parseQualifiedNameStr(unquotedName string) (pkgpath, name string) {
	parts := strings.Split(unquotedName, ".")
	if parts[0] == "" {
		parts = parts[1:]
	}

	switch len(parts) {
	case 0:
		p.errorf("malformed qualified name: %q", unquotedName)
	case 1:
		// unqualified name
		pkgpath = p.pkgpath
		name = parts[0]
	default:
		// qualified name, which may contain periods
		pkgpath = strings.Join(parts[0:len(parts)-1], ".")
		name = parts[len(parts)-1]
	}

	return
}

// getPkg returns the package for a given path. If the package is
// not found but we have a package name, create the package and
// add it to the p.imports map.
func (p *parser) getPkg(pkgpath, name string) *types.Package {
	// package unsafe is not in the imports map - handle explicitly
	if pkgpath == "unsafe" {
		return types.Unsafe
	}
	pkg := p.imports[pkgpath]
	if pkg == nil && name != "" {
		pkg = types.NewPackage(pkgpath, name)
		p.imports[pkgpath] = pkg
	}
	return pkg
}

// parseExportedName is like parseQualifiedName, but
// the package path is resolved to an imported *types.Package.
//
//	ExportedName = string [string] .
func (p *parser) parseExportedName() (pkg *types.Package, name string) {
	path, name := p.parseQualifiedName()
	var pkgname string
	if p.tok == scanner.String {
		pkgname = p.parseString()
	}
	pkg = p.getPkg(path, pkgname)
	if pkg == nil {
		p.errorf("package %s (path = %q) not found", name, path)
	}
	return
}

// parseName parses a Name:
//
//	Name = QualifiedName | "?" .
func (p *parser) parseName() string {
	if p.tok == '?' {
		// Anonymous.
		p.next()
		return ""
	}
	// The package path is redundant for us. Don't try to parse it.
	_, name := p.parseUnquotedQualifiedName()
	return name
}

// parseField parses a Field:
//
//	Field = Name Type [string] .
func (p *parser) parseField(pkg *types.Package) (field *types.Var, tag string) {
	name := p.parseName()
	typ, n := p.parseTypeExtended(pkg)
	anon := false
	if name == "" {
		anon = true
		// Alias?
		if aname, ok := p.aliases[n]; ok {
			name = aname
		} else {
			switch typ := types.Unalias(typesinternal.Unpointer(typ)).(type) {
			case *types.Basic:
				name = typ.Name()
			case *types.Named:
				name = typ.Obj().Name()
			default:
				p.error("embedded field expected")
			}
		}
	}
	field = types.NewField(token.NoPos, pkg, name, typ, anon)
	if p.tok == scanner.String {
		tag = p.parseString()
	}
	return
}

// parseParam parses a Param:
//
//	Param = Name ["..."] Type .
func (p *parser) parseParam(pkg *types.Package) (param *types.Var, isVariadic bool) {
	name := p.parseName()
	// Ignore names invented for inlinable functions.
	if strings.HasPrefix(name, "p.") || strings.HasPrefix(name, "r.") || strings.HasPrefix(name, "$ret") {
		name = ""
	}
	if p.tok == '<' && p.scanner.Peek() == 'e' {
		// EscInfo = "<esc:" int ">" . (optional and ignored)
		p.next()
		p.expectKeyword("esc")
		p.expect(':')
		p.expect(scanner.Int)
		p.expect('>')
	}
	if p.tok == '.' {
		p.next()
		p.expect('.')
		p.expect('.')
		isVariadic = true
	}
	typ := p.parseType(pkg)
	if isVariadic {
		typ = types.NewSlice(typ)
	}
	param = types.NewParam(token.NoPos, pkg, name, typ)
	return
}

// parseVar parses a Var:
//
//	Var = Name Type .
func (p *parser) parseVar(pkg *types.Package) *types.Var {
	name := p.parseName()
	v := types.NewVar(token.NoPos, pkg, name, p.parseType(pkg))
	typesinternal.SetVarKind(v, typesinternal.PackageVar)
	if name[0] == '.' || name[0] == '<' {
		// This is an unexported variable,
		// or a variable defined in a different package.
		// We only want to record exported variables.
		return nil
	}
	return v
}

// parseConversion parses a Conversion:
//
//	Conversion = "convert" "(" Type "," ConstValue ")" .
func (p *parser) parseConversion(pkg *types.Package) (val constant.Value, typ types.Type) {
	p.expectKeyword("convert")
	p.expect('(')
	typ = p.parseType(pkg)
	p.expect(',')
	val, _ = p.parseConstValue(pkg)
	p.expect(')')
	return
}

// parseConstValue parses a ConstValue:
//
//	ConstValue     = string | "false" | "true" | ["-"] (int ["'"] | FloatOrComplex) | Conversion .
//	FloatOrComplex = float ["i" | ("+"|"-") float "i"] .
func (p *parser) parseConstValue(pkg *types.Package) (val constant.Value, typ types.Type) {
	// v3 changed to $false, $true, $convert, to avoid confusion
	// with variable names in inline function bodies.
	if p.tok == '$' {
		p.next()
		if p.tok != scanner.Ident {
			p.errorf("expected identifier after '$', got %s (%q)", scanner.TokenString(p.tok), p.lit)
		}
	}

	switch p.tok {
	case scanner.String:
		str := p.parseString()
		val = constant.MakeString(str)
		typ = types.Typ[types.UntypedString]
		return

	case scanner.Ident:
		b := false
		switch p.lit {
		case "false":
		case "true":
			b = true

		case "convert":
			return p.parseConversion(pkg)

		default:
			p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
		}

		p.next()
		val = constant.MakeBool(b)
		typ = types.Typ[types.UntypedBool]
		return
	}

	sign := ""
	if p.tok == '-' {
		p.next()
		sign = "-"
	}

	switch p.tok {
	case scanner.Int:
		val = constant.MakeFromLiteral(sign+p.lit, token.INT, 0)
		if val == nil {
			p.error("could not parse integer literal")
		}

		p.next()
		if p.tok == '\'' {
			p.next()
			typ = types.Typ[types.UntypedRune]
		} else {
			typ = types.Typ[types.UntypedInt]
		}

	case scanner.Float:
		re := sign + p.lit
		p.next()

		var im string
		switch p.tok {
		case '+':
			p.next()
			im = p.expect(scanner.Float)

		case '-':
			p.next()
			im = "-" + p.expect(scanner.Float)

		case scanner.Ident:
			// re is in fact the imaginary component. Expect "i" below.
			im = re
			re = "0"

		default:
			val = constant.MakeFromLiteral(re, token.FLOAT, 0)
			if val == nil {
				p.error("could not parse float literal")
			}
			typ = types.Typ[types.UntypedFloat]
			return
		}

		p.expectKeyword("i")
		reval := constant.MakeFromLiteral(re, token.FLOAT, 0)
		if reval == nil {
			p.error("could not parse real component of complex literal")
		}
		imval := constant.MakeFromLiteral(im+"i", token.IMAG, 0)
		if imval == nil {
			p.error("could not parse imag component of complex literal")
		}
		val = constant.BinaryOp(reval, token.ADD, imval)
		typ = types.Typ[types.UntypedComplex]

	default:
		p.errorf("expected const value, got %s (%q)", scanner.TokenString(p.tok), p.lit)
	}

	return
}

// parseConst parses a Const:
//
//	Const = Name [Type] "=" ConstValue .
func (p *parser) parseConst(pkg *types.Package) *types.Const {
	name := p.parseName()
	var typ types.Type
	if p.tok == '<' {
		typ = p.parseType(pkg)
	}
	p.expect('=')
	val, vtyp := p.parseConstValue(pkg)
	if typ == nil {
		typ = vtyp
	}
	return types.NewConst(token.NoPos, pkg, name, typ, val)
}

// reserved is a singleton type used to fill type map slots that have
// been reserved (i.e., for which a type number has been parsed) but
// which don't have their actual type yet. When the type map is updated,
// the actual type must replace a reserved entry (or we have an internal
// error). Used for self-verification only - not required for correctness.
var reserved = new(struct{ types.Type })

// reserve reserves the type map entry n for future use.
func (p *parser) reserve(n int) {
	// Notes:
	// - for pre-V3 export data, the type numbers we see are
	//   guaranteed to be in increasing order, so we append a
	//   reserved entry onto the list.
	// - for V3+ export data, type numbers can appear in
	//   any order, however the 'types' section tells us the
	//   total number of types, hence typeList is pre-allocated.
	if len(p.typeData) == 0 {
		if n != len(p.typeList) {
			p.errorf("invalid type number %d (out of sync)", n)
		}
		p.typeList = append(p.typeList, reserved)
	} else {
		if p.typeList[n] != nil {
			p.errorf("previously visited type number %d", n)
		}
		p.typeList[n] = reserved
	}
}

// update sets the type map entries for the entries in nlist to t.
// An entry in nlist can be a type number in p.typeList,
// used to resolve named types, or it can be a *types.Pointer,
// used to resolve pointers to named types in case they are referenced
// by embedded fields.
func (p *parser) update(t types.Type, nlist []any) {
	if t == reserved {
		p.errorf("internal error: update(%v) invoked on reserved", nlist)
	}
	if t == nil {
		p.errorf("internal error: update(%v) invoked on nil", nlist)
	}
	for _, n := range nlist {
		switch n := n.(type) {
		case int:
			if p.typeList[n] == t {
				continue
			}
			if p.typeList[n] != reserved {
				p.errorf("internal error: update(%v): %d not reserved", nlist, n)
			}
			p.typeList[n] = t
		case *types.Pointer:
			if *n != (types.Pointer{}) {
				elem := n.Elem()
				if elem == t {
					continue
				}
				p.errorf("internal error: update: pointer already set to %v, expected %v", elem, t)
			}
			*n = *types.NewPointer(t)
		default:
			p.errorf("internal error: %T on nlist", n)
		}
	}
}

// parseNamedType parses a NamedType:
//
//	NamedType = TypeName [ "=" ] Type { Method } .
//	TypeName  = ExportedName .
//	Method    = "func" "(" Param ")" Name ParamList ResultList [InlineBody] ";" .
func (p *parser) parseNamedType(nlist []any) types.Type {
	pkg, name := p.parseExportedName()
	scope := pkg.Scope()
	obj := scope.Lookup(name)
	if obj != nil && obj.Type() == nil {
		p.errorf("%v has nil type", obj)
	}

	if p.tok == scanner.Ident && p.lit == "notinheap" {
		p.next()
		// The go/types package has no way of recording that
		// this type is marked notinheap. Presumably no user
		// of this package actually cares.
	}

	// type alias
	if p.tok == '=' {
		p.next()
		p.aliases[nlist[len(nlist)-1].(int)] = name
		if obj != nil {
			// use the previously imported (canonical) type
			t := obj.Type()
			p.update(t, nlist)
			p.parseType(pkg) // discard
			return t
		}
		t := p.parseType(pkg, nlist...)
		obj = types.NewTypeName(token.NoPos, pkg, name, t)
		scope.Insert(obj)
		return t
	}

	// defined type
	if obj == nil {
		// A named type may be referred to before the underlying type
		// is known - set it up.
		tname := types.NewTypeName(token.NoPos, pkg, name, nil)
		types.NewNamed(tname, nil, nil)
		scope.Insert(tname)
		obj = tname
	}

	// use the previously imported (canonical), or newly created type
	t := obj.Type()
	p.update(t, nlist)

	nt, ok := types.Unalias(t).(*types.Named)
	if !ok {
		// This can happen for unsafe.Pointer, which is a TypeName holding a Basic type.
		pt := p.parseType(pkg)
		if pt != t {
			p.error("unexpected underlying type for non-named TypeName")
		}
		return t
	}

	underlying := p.parseType(pkg)
	if nt.Underlying() == nil {
		if underlying.Underlying() == nil {
			fix := fixupRecord{toUpdate: nt, target: underlying}
			p.fixups = append(p.fixups, fix)
		} else {
			nt.SetUnderlying(underlying.Underlying())
		}
	}

	if p.tok == '\n' {
		p.next()
		// collect associated methods
		for p.tok == scanner.Ident {
			p.expectKeyword("func")
			if p.tok == '/' {
				// Skip a /*nointerface*/ or /*asm ID */ comment.
				p.expect('/')
				p.expect('*')
				if p.expect(scanner.Ident) == "asm" {
					p.parseUnquotedString()
				}
				p.expect('*')
				p.expect('/')
			}
			p.expect('(')
			receiver, _ := p.parseParam(pkg)
			p.expect(')')
			name := p.parseName()
			params, isVariadic := p.parseParamList(pkg)
			results := p.parseResultList(pkg)
			p.skipInlineBody()
			p.expectEOL()

			sig := types.NewSignatureType(receiver, nil, nil, params, results, isVariadic)
			nt.AddMethod(types.NewFunc(token.NoPos, pkg, name, sig))
		}
	}

	return nt
}

func (p *parser) parseInt64() int64 {
	lit := p.expect(scanner.Int)
	n, err := strconv.ParseInt(lit, 10, 64)
	if err != nil {
		p.error(err)
	}
	return n
}

func (p *parser) parseInt() int {
	lit := p.expect(scanner.Int)
	n, err := strconv.ParseInt(lit, 10, 0 /* int */)
	if err != nil {
		p.error(err)
	}
	return int(n)
}

// parseArrayOrSliceType parses an ArrayOrSliceType:
//
//	ArrayOrSliceType = "[" [ int ] "]" Type .
func (p *parser) parseArrayOrSliceType(pkg *types.Package, nlist []any) types.Type {
	p.expect('[')
	if p.tok == ']' {
		p.next()

		t := new(types.Slice)
		p.update(t, nlist)

		*t = *types.NewSlice(p.parseType(pkg))
		return t
	}

	t := new(types.Array)
	p.update(t, nlist)

	len := p.parseInt64()
	p.expect(']')

	*t = *types.NewArray(p.parseType(pkg), len)
	return t
}

// parseMapType parses a MapType:
//
//	MapType = "map" "[" Type "]" Type .
func (p *parser) parseMapType(pkg *types.Package, nlist []any) types.Type {
	p.expectKeyword("map")

	t := new(types.Map)
	p.update(t, nlist)

	p.expect('[')
	key := p.parseType(pkg)
	p.expect(']')
	elem := p.parseType(pkg)

	*t = *types.NewMap(key, elem)
	return t
}

// parseChanType parses a ChanType:
//
//	ChanType = "chan" ["<-" | "-<"] Type .
func (p *parser) parseChanType(pkg *types.Package, nlist []any) types.Type {
	p.expectKeyword("chan")

	t := new(types.Chan)
	p.update(t, nlist)

	dir := types.SendRecv
	switch p.tok {
	case '-':
		p.next()
		p.expect('<')
		dir = types.SendOnly

	case '<':
		// don't consume '<' if it belongs to Type
		if p.scanner.Peek() == '-' {
			p.next()
			p.expect('-')
			dir = types.RecvOnly
		}
	}

	*t = *types.NewChan(dir, p.parseType(pkg))
	return t
}

// parseStructType parses a StructType:
//
//	StructType = "struct" "{" { Field } "}" .
func (p *parser) parseStructType(pkg *types.Package, nlist []any) types.Type {
	p.expectKeyword("struct")

	t := new(types.Struct)
	p.update(t, nlist)

	var fields []*types.Var
	var tags []string

	p.expect('{')
	for p.tok != '}' && p.tok != scanner.EOF {
		field, tag := p.parseField(pkg)
		p.expect(';')
		fields = append(fields, field)
		tags = append(tags, tag)
	}
	p.expect('}')

	*t = *types.NewStruct(fields, tags)
	return t
}

// parseParamList parses a ParamList:
//
//	ParamList = "(" [ { Parameter "," } Parameter ] ")" .
func (p *parser) parseParamList(pkg *types.Package) (*types.Tuple, bool) {
	var list []*types.Var
	isVariadic := false

	p.expect('(')
	for p.tok != ')' && p.tok != scanner.EOF {
		if len(list) > 0 {
			p.expect(',')
		}
		par, variadic := p.parseParam(pkg)
		list = append(list, par)
		if variadic {
			if isVariadic {
				p.error("... not on final argument")
			}
			isVariadic = true
		}
	}
	p.expect(')')

	return types.NewTuple(list...), isVariadic
}

// parseResultList parses a ResultList:
//
//	ResultList = Type | ParamList .
func (p *parser) parseResultList(pkg *types.Package) *types.Tuple {
	switch p.tok {
	case '<':
		p.next()
		if p.tok == scanner.Ident && p.lit == "inl" {
			return nil
		}
		taa, _ := p.parseTypeAfterAngle(pkg)
		return types.NewTuple(types.NewParam(token.NoPos, pkg, "", taa))

	case '(':
		params, _ := p.parseParamList(pkg)
		return params

	default:
		return nil
	}
}

// parseFunctionType parses a FunctionType:
//
//	FunctionType = ParamList ResultList .
func (p *parser) parseFunctionType(pkg *types.Package, nlist []any) *types.Signature {
	t := new(types.Signature)
	p.update(t, nlist)

	params, isVariadic := p.parseParamList(pkg)
	results := p.parseResultList(pkg)

	*t = *types.NewSignatureType(nil, nil, nil, params, results, isVariadic)
	return t
}

// parseFunc parses a Func:
//
//	Func = Name FunctionType [InlineBody] .
func (p *parser) parseFunc(pkg *types.Package) *types.Func {
	if p.tok == '/' {
		// Skip an /*asm ID */ comment.
		p.expect('/')
		p.expect('*')
		if p.expect(scanner.Ident) == "asm" {
			p.parseUnquotedString()
		}
		p.expect('*')
		p.expect('/')
	}

	name := p.parseName()
	f := types.NewFunc(token.NoPos, pkg, name, p.parseFunctionType(pkg, nil))
	p.skipInlineBody()

	if name[0] == '.' || name[0] == '<' || strings.ContainsRune(name, '$') {
		// This is an unexported function,
		// or a function defined in a different package,
		// or a type$equal or type$hash function.
		// We only want to record exported functions.
		return nil
	}

	return f
}

// parseInterfaceType parses an InterfaceType:
//
//	InterfaceType = "interface" "{" { ("?" Type | Func) ";" } "}" .
func (p *parser) parseInterfaceType(pkg *types.Package, nlist []any) types.Type {
	p.expectKeyword("interface")

	t := new(types.Interface)
	p.update(t, nlist)

	var methods []*types.Func
	var embeddeds []types.Type

	p.expect('{')
	for p.tok != '}' && p.tok != scanner.EOF {
		if p.tok == '?' {
			p.next()
			embeddeds = append(embeddeds, p.parseType(pkg))
		} else {
			method := p.parseFunc(pkg)
			if method != nil {
				methods = append(methods, method)
			}
		}
		p.expect(';')
	}
	p.expect('}')

	*t = *newInterface(methods, embeddeds)
	return t
}

// parsePointerType parses a PointerType:
//
//	PointerType = "*" ("any" | Type) .
func (p *parser) parsePointerType(pkg *types.Package, nlist []any) types.Type {
	p.expect('*')
	if p.tok == scanner.Ident {
		p.expectKeyword("any")
		t := types.Typ[types.UnsafePointer]
		p.update(t, nlist)
		return t
	}

	t := new(types.Pointer)
	p.update(t, nlist)

	*t = *types.NewPointer(p.parseType(pkg, t))

	return t
}

// parseTypeSpec parses a TypeSpec:
//
//	TypeSpec = NamedType | MapType | ChanType | StructType | InterfaceType | PointerType | ArrayOrSliceType | FunctionType .
func (p *parser) parseTypeSpec(pkg *types.Package, nlist []any) types.Type {
	switch p.tok {
	case scanner.String:
		return p.parseNamedType(nlist)

	case scanner.Ident:
		switch p.lit {
		case "map":
			return p.parseMapType(pkg, nlist)

		case "chan":
			return p.parseChanType(pkg, nlist)

		case "struct":
			return p.parseStructType(pkg, nlist)

		case "interface":
			return p.parseInterfaceType(pkg, nlist)
		}

	case '*':
		return p.parsePointerType(pkg, nlist)

	case '[':
		return p.parseArrayOrSliceType(pkg, nlist)

	case '(':
		return p.parseFunctionType(pkg, nlist)
	}

	p.errorf("expected type name or literal, got %s", scanner.TokenString(p.tok))
	return nil
}

const (
	// From gofrontend/go/export.h
	// Note that these values are negative in the gofrontend and have been made positive
	// in the gccgoimporter.
	gccgoBuiltinINT8       = 1
	gccgoBuiltinINT16      = 2
	gccgoBuiltinINT32      = 3
	gccgoBuiltinINT64      = 4
	gccgoBuiltinUINT8      = 5
	gccgoBuiltinUINT16     = 6
	gccgoBuiltinUINT32     = 7
	gccgoBuiltinUINT64     = 8
	gccgoBuiltinFLOAT32    = 9
	gccgoBuiltinFLOAT64    = 10
	gccgoBuiltinINT        = 11
	gccgoBuiltinUINT       = 12
	gccgoBuiltinUINTPTR    = 13
	gccgoBuiltinBOOL       = 15
	gccgoBuiltinSTRING     = 16
	gccgoBuiltinCOMPLEX64  = 17
	gccgoBuiltinCOMPLEX128 = 18
	gccgoBuiltinERROR      = 19
	gccgoBuiltinBYTE       = 20
	gccgoBuiltinRUNE       = 21
	gccgoBuiltinANY        = 22
)

func lookupBuiltinType(typ int) types.Type {
	return [...]types.Type{
		gccgoBuiltinINT8:       types.Typ[types.Int8],
		gccgoBuiltinINT16:      types.Typ[types.Int16],
		gccgoBuiltinINT32:      types.Typ[types.Int32],
		gccgoBuiltinINT64:      types.Typ[types.Int64],
		gccgoBuiltinUINT8:      types.Typ[types.Uint8],
		gccgoBuiltinUINT16:     types.Typ[types.Uint16],
		gccgoBuiltinUINT32:     types.Typ[types.Uint32],
		gccgoBuiltinUINT64:     types.Typ[types.Uint64],
		gccgoBuiltinFLOAT32:    types.Typ[types.Float32],
		gccgoBuiltinFLOAT64:    types.Typ[types.Float64],
		gccgoBuiltinINT:        types.Typ[types.Int],
		gccgoBuiltinUINT:       types.Typ[types.Uint],
		gccgoBuiltinUINTPTR:    types.Typ[types.Uintptr],
		gccgoBuiltinBOOL:       types.Typ[types.Bool],
		gccgoBuiltinSTRING:     types.Typ[types.String],
		gccgoBuiltinCOMPLEX64:  types.Typ[types.Complex64],
		gccgoBuiltinCOMPLEX128: types.Typ[types.Complex128],
		gccgoBuiltinERROR:      types.Universe.Lookup("error").Type(),
		gccgoBuiltinBYTE:       types.Universe.Lookup("byte").Type(),
		gccgoBuiltinRUNE:       types.Universe.Lookup("rune").Type(),
		gccgoBuiltinANY:        types.Universe.Lookup("any").Type(),
	}[typ]
}

// parseType parses a Type:
//
//	Type = "<" "type" ( "-" int | int [ TypeSpec ] ) ">" .
//
// parseType updates the type map to t for all type numbers n.
func (p *parser) parseType(pkg *types.Package, n ...any) types.Type {
	p.expect('<')
	t, _ := p.parseTypeAfterAngle(pkg, n...)
	return t
}

// (*parser).Type after reading the "<".
func (p *parser) parseTypeAfterAngle(pkg *types.Package, n ...any) (t types.Type, n1 int) {
	p.expectKeyword("type")

	n1 = 0
	switch p.tok {
	case scanner.Int:
		n1 = p.parseInt()
		if p.tok == '>' {
			if len(p.typeData) > 0 && p.typeList[n1] == nil {
				p.parseSavedType(pkg, n1, n)
			}
			t = p.typeList[n1]
			if len(p.typeData) == 0 && t == reserved {
				p.errorf("invalid type cycle, type %d not yet defined (nlist=%v)", n1, n)
			}
			p.update(t, n)
		} else {
			p.reserve(n1)
			t = p.parseTypeSpec(pkg, append(n, n1))
		}

	case '-':
		p.next()
		n1 := p.parseInt()
		t = lookupBuiltinType(n1)
		p.update(t, n)

	default:
		p.errorf("expected type number, got %s (%q)", scanner.TokenString(p.tok), p.lit)
		return nil, 0
	}

	if t == nil || t == reserved {
		p.errorf("internal error: bad return from parseType(%v)", n)
	}

	p.expect('>')
	return
}

// parseTypeExtended is identical to parseType, but if the type in
// question is a saved type, returns the index as well as the type
// pointer (index returned is zero if we parsed a builtin).
func (p *parser) parseTypeExtended(pkg *types.Package, n ...any) (t types.Type, n1 int) {
	p.expect('<')
	t, n1 = p.parseTypeAfterAngle(pkg, n...)
	return
}

// InlineBody = "<inl:NN>" .{NN}
// Reports whether a body was skipped.
func (p *parser) skipInlineBody() {
	// We may or may not have seen the '<' already, depending on
	// whether the function had a result type or not.
	if p.tok == '<' {
		p.next()
		p.expectKeyword("inl")
	} else if p.tok != scanner.Ident || p.lit != "inl" {
		return
	} else {
		p.next()
	}

	p.expect(':')
	want := p.parseInt()
	p.expect('>')

	defer func(w uint64) {
		p.scanner.Whitespace = w
	}(p.scanner.Whitespace)
	p.scanner.Whitespace = 0

	got := 0
	for got < want {
		r := p.scanner.Next()
		if r == scanner.EOF {
			p.error("unexpected EOF")
		}
		got += utf8.RuneLen(r)
	}
}

// parseTypes parses a Types:
//
//	Types = "types" maxp1 exportedp1 (offset length)* .
func (p *parser) parseTypes(pkg *types.Package) {
	maxp1 := p.parseInt()
	exportedp1 := p.parseInt()
	p.typeList = make([]types.Type, maxp1)

	type typeOffset struct {
		offset int
		length int
	}
	var typeOffsets []typeOffset

	total := 0
	for i := 1; i < maxp1; i++ {
		len := p.parseInt()
		typeOffsets = append(typeOffsets, typeOffset{total, len})
		total += len
	}

	defer func(w uint64) {
		p.scanner.Whitespace = w
	}(p.scanner.Whitespace)
	p.scanner.Whitespace = 0

	// We should now have p.tok pointing to the final newline.
	// The next runes from the scanner should be the type data.

	var sb strings.Builder
	for sb.Len() < total {
		r := p.scanner.Next()
		if r == scanner.EOF {
			p.error("unexpected EOF")
		}
		sb.WriteRune(r)
	}
	allTypeData := sb.String()

	p.typeData = []string{""} // type 0, unused
	for _, to := range typeOffsets {
		p.typeData = append(p.typeData, allTypeData[to.offset:to.offset+to.length])
	}

	for i := 1; i < int(exportedp1); i++ {
		p.parseSavedType(pkg, i, nil)
	}
}

// parseSavedType parses one saved type definition.
func (p *parser) parseSavedType(pkg *types.Package, i int, nlist []any) {
	defer func(s *scanner.Scanner, tok rune, lit string) {
		p.scanner = s
		p.tok = tok
		p.lit = lit
	}(p.scanner, p.tok, p.lit)

	p.scanner = new(scanner.Scanner)
	p.initScanner(p.scanner.Filename, strings.NewReader(p.typeData[i]))
	p.expectKeyword("type")
	id := p.parseInt()
	if id != i {
		p.errorf("type ID mismatch: got %d, want %d", id, i)
	}
	if p.typeList[i] == reserved {
		p.errorf("internal error: %d already reserved in parseSavedType", i)
	}
	if p.typeList[i] == nil {
		p.reserve(i)
		p.parseTypeSpec(pkg, append(nlist, i))
	}
	if p.typeList[i] == nil || p.typeList[i] == reserved {
		p.errorf("internal error: parseSavedType(%d,%v) reserved/nil", i, nlist)
	}
}

// parsePackageInit parses a PackageInit:
//
//	PackageInit = unquotedString unquotedString int .
func (p *parser) parsePackageInit() PackageInit {
	name := p.parseUnquotedString()
	initfunc := p.parseUnquotedString()
	priority := -1
	if p.version == "v1" {
		priority = p.parseInt()
	}
	return PackageInit{Name: name, InitFunc: initfunc, Priority: priority}
}

// Create the package if we have parsed both the package path and package name.
func (p *parser) maybeCreatePackage() {
	if p.pkgname != "" && p.pkgpath != "" {
		p.pkg = p.getPkg(p.pkgpath, p.pkgname)
	}
}

// parseInitDataDirective parses an InitDataDirective:
//
//	InitDataDirective = ( "v1" | "v2" | "v3" ) ";" |
//		"priority" int ";" |
//		"init" { PackageInit } ";" |
//		"checksum" unquotedString ";" .
func (p *parser) parseInitDataDirective() {
	if p.tok != scanner.Ident {
		// unexpected token kind; panic
		p.expect(scanner.Ident)
	}

	switch p.lit {
	case "v1", "v2", "v3":
		p.version = p.lit
		p.next()
		p.expect(';')
		p.expect('\n')

	case "priority":
		p.next()
		p.initdata.Priority = p.parseInt()
		p.expectEOL()

	case "init":
		p.next()
		for p.tok != '\n' && p.tok != ';' && p.tok != scanner.EOF {
			p.initdata.Inits = append(p.initdata.Inits, p.parsePackageInit())
		}
		p.expectEOL()

	case "init_graph":
		p.next()
		// The graph data is thrown away for now.
		for p.tok != '\n' && p.tok != ';' && p.tok != scanner.EOF {
			p.parseInt64()
			p.parseInt64()
		}
		p.expectEOL()

	case "checksum":
		// Don't let the scanner try to parse the checksum as a number.
		defer func(mode uint) {
			p.scanner.Mode = mode
		}(p.scanner.Mode)
		p.scanner.Mode &^= scanner.ScanInts | scanner.ScanFloats
		p.next()
		p.parseUnquotedString()
		p.expectEOL()

	default:
		p.errorf("unexpected identifier: %q", p.lit)
	}
}

// parseDirective parses a Directive:
//
//	Directive = InitDataDirective |
//		"package" unquotedString [ unquotedString ] [ unquotedString ] ";" |
//		"pkgpath" unquotedString ";" |
//		"prefix" unquotedString ";" |
//		"import" unquotedString unquotedString string ";" |
//		"indirectimport" unquotedString unquotedstring ";" |
//		"func" Func ";" |
//		"type" Type ";" |
//		"var" Var ";" |
//		"const" Const ";" .
func (p *parser) parseDirective() {
	if p.tok != scanner.Ident {
		// unexpected token kind; panic
		p.expect(scanner.Ident)
	}

	switch p.lit {
	case "v1", "v2", "v3", "priority", "init", "init_graph", "checksum":
		p.parseInitDataDirective()

	case "package":
		p.next()
		p.pkgname = p.parseUnquotedString()
		p.maybeCreatePackage()
		if p.version != "v1" && p.tok != '\n' && p.tok != ';' {
			p.parseUnquotedString()
			p.parseUnquotedString()
		}
		p.expectEOL()

	case "pkgpath":
		p.next()
		p.pkgpath = p.parseUnquotedString()
		p.maybeCreatePackage()
		p.expectEOL()

	case "prefix":
		p.next()
		p.pkgpath = p.parseUnquotedString()
		p.expectEOL()

	case "import":
		p.next()
		pkgname := p.parseUnquotedString()
		pkgpath := p.parseUnquotedString()
		p.getPkg(pkgpath, pkgname)
		p.parseString()
		p.expectEOL()

	case "indirectimport":
		p.next()
		pkgname := p.parseUnquotedString()
		pkgpath := p.parseUnquotedString()
		p.getPkg(pkgpath, pkgname)
		p.expectEOL()

	case "types":
		p.next()
		p.parseTypes(p.pkg)
		p.expectEOL()

	case "func":
		p.next()
		fun := p.parseFunc(p.pkg)
		if fun != nil {
			p.pkg.Scope().Insert(fun)
		}
		p.expectEOL()

	case "type":
		p.next()
		p.parseType(p.pkg)
		p.expectEOL()

	case "var":
		p.next()
		v := p.parseVar(p.pkg)
		if v != nil {
			p.pkg.Scope().Insert(v)
		}
		p.expectEOL()

	case "const":
		p.next()
		c := p.parseConst(p.pkg)
		p.pkg.Scope().Insert(c)
		p.expectEOL()

	default:
		p.errorf("unexpected identifier: %q", p.lit)
	}
}

// parsePackage parses a Package:
//
//	Package = { Directive } .
func (p *parser) parsePackage() *types.Package {
	for p.tok != scanner.EOF {
		p.parseDirective()
	}
	for _, f := range p.fixups {
		if f.target.Underlying() == nil {
			p.errorf("internal error: fixup can't be applied, loop required")
		}
		f.toUpdate.SetUnderlying(f.target.Underlying())
	}
	p.fixups = nil
	for _, typ := range p.typeList {
		if it, ok := types.Unalias(typ).(*types.Interface); ok {
			it.Complete()
		}
	}
	p.pkg.MarkComplete()
	return p.pkg
}


================================================
FILE: go/internal/gccgoimporter/parser_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Except for this comment, this file is a verbatim copy of the file
// with the same name in $GOROOT/src/go/internal/gccgoimporter.

package gccgoimporter

import (
	"bytes"
	"go/types"
	"strings"
	"testing"
	"text/scanner"
)

var typeParserTests = []struct {
	id, typ, want, underlying, methods string
}{
	{id: "foo", typ: "<type -1>", want: "int8"},
	{id: "foo", typ: "<type 1 *<type -19>>", want: "*error"},
	{id: "foo", typ: "<type 1 *any>", want: "unsafe.Pointer"},
	{id: "foo", typ: "<type 1 \"Bar\" <type 2 *<type 1>>>", want: "foo.Bar", underlying: "*foo.Bar"},
	{id: "foo", typ: "<type 1 \"bar.Foo\" \"bar\" <type -1>\nfunc (? <type 1>) M ();\n>", want: "bar.Foo", underlying: "int8", methods: "func (bar.Foo).M()"},
	{id: "foo", typ: "<type 1 \".bar.foo\" \"bar\" <type -1>>", want: "bar.foo", underlying: "int8"},
	{id: "foo", typ: "<type 1 []<type -1>>", want: "[]int8"},
	{id: "foo", typ: "<type 1 [42]<type -1>>", want: "[42]int8"},
	{id: "foo", typ: "<type 1 map [<type -1>] <type -2>>", want: "map[int8]int16"},
	{id: "foo", typ: "<type 1 chan <type -1>>", want: "chan int8"},
	{id: "foo", typ: "<type 1 chan <- <type -1>>", want: "<-chan int8"},
	{id: "foo", typ: "<type 1 chan -< <type -1>>", want: "chan<- int8"},
	{id: "foo", typ: "<type 1 struct { I8 <type -1>; I16 <type -2> \"i16\"; }>", want: "struct{I8 int8; I16 int16 \"i16\"}"},
	{id: "foo", typ: "<type 1 interface { Foo (a <type -1>, b <type -2>) <type -1>; Bar (? <type -2>, ? ...<type -1>) (? <type -2>, ? <type -1>); Baz (); }>", want: "interface{Bar(int16, ...int8) (int16, int8); Baz(); Foo(a int8, b int16) int8}"},
	{id: "foo", typ: "<type 1 (? <type -1>) <type -2>>", want: "func(int8) int16"},
}

func TestTypeParser(t *testing.T) {
	for _, test := range typeParserTests {
		var p parser
		p.init("test.gox", strings.NewReader(test.typ), make(map[string]*types.Package))
		p.version = "v2"
		p.pkgname = test.id
		p.pkgpath = test.id
		p.maybeCreatePackage()
		typ := p.parseType(p.pkg)

		if p.tok != scanner.EOF {
			t.Errorf("expected full parse, stopped at %q", p.lit)
		}

		// interfaces must be explicitly completed
		if ityp, _ := typ.(*types.Interface); ityp != nil {
			ityp.Complete()
		}

		got := typ.String()
		if got != test.want {
			t.Errorf("got type %q, expected %q", got, test.want)
		}

		if test.underlying != "" {
			underlying := typ.Underlying().String()
			if underlying != test.underlying {
				t.Errorf("got underlying type %q, expected %q", underlying, test.underlying)
			}
		}

		if test.methods != "" {
			nt := typ.(*types.Named)
			var buf bytes.Buffer
			for i := 0; i != nt.NumMethods(); i++ {
				buf.WriteString(nt.Method(i).String())
			}
			methods := buf.String()
			if methods != test.methods {
				t.Errorf("got methods %q, expected %q", methods, test.methods)
			}
		}
	}
}


================================================
FILE: go/internal/gccgoimporter/testdata/aliases.go
================================================
package aliases

type (
	T0 [10]int
	T1 []byte
	T2 struct {
		x int
	}
	T3 interface {
		m() T2
	}
	T4 func(int, T0) chan T2
)

// basic aliases
type (
	Ai = int
	A0 = T0
	A1 = T1
	A2 = T2
	A3 = T3
	A4 = T4

	A10 = [10]int
	A11 = []byte
	A12 = struct {
		x int
	}
	A13 = interface {
		m() A2
	}
	A14 = func(int, A0) chan A2
)

// alias receiver types
func (T0) m1() {}
func (A0) m2() {}

// alias receiver types (long type declaration chains)
type (
	V0 = V1
	V1 = (V2)
	V2 = (V3)
	V3 = T0
)

func (V1) n() {}

// cycles
type C0 struct {
	f1 C1
	f2 C2
}

type (
	C1 *C0
	C2 = C1
)

type (
	C5 struct {
		f *C6
	}
	C6 = C5
)


================================================
FILE: go/internal/gccgoimporter/testdata/aliases.gox
================================================
v2;
package aliases;
prefix go;
package aliases go.aliases go.aliases;
type <type 1 "A0" = <type 2 "T0" <type 3 [10 ] <type -11>>
 func (? <esc:0x1> <type 2>) .go.aliases.m1 ();
 func (? <esc:0x1> <type 1>) .go.aliases.m2 ();
 func (? <esc:0x1> <type 4 "V1" = <type 5 "V2" = <type 6 "V3" = <type 2>>>>) .go.aliases.n ();
>>;
type <type 7 "A1" = <type 8 "T1" <type 9 [] <type -20>>>>;
type <type 10 "A10" = <type 11 [10 ] <type -11>>>;
type <type 12 "A11" = <type 13 [] <type -20>>>;
type <type 14 "A12" = <type 15 struct { .go.aliases.x <type -11>; }>>;
type <type 16 "A13" = <type 17 interface { .go.aliases.m () <type 18 "A2" = <type 19 "T2" <type 20 struct { .go.aliases.x <type -11>; }>>>; }>>;
type <type 21 "A14" = <type 22 (? <type -11>, ? <type 1>) <type 23 chan <type 18>>>>;
type <type 18>;
type <type 24 "A3" = <type 25 "T3" <type 26 interface { .go.aliases.m () <type 19>; }>>>;
type <type 27 "A4" = <type 28 "T4" <type 29 (? <type -11>, ? <type 2>) <type 30 chan <type 19>>>>>;
type <type 31 "Ai" = <type -11>>;
type <type 32 "C0" <type 33 struct { .go.aliases.f1 <type 34 "C1" <type 35 *<type 32>>>; .go.aliases.f2 <type 36 "C2" = <type 34>>; }>>;
type <type 34>;
type <type 36>;
type <type 37 "C5" <type 38 struct { .go.aliases.f <type 39 *<type 40 "C6" = <type 37>>>; }>>;
type <type 40>;
type <type 2>;
type <type 8>;
type <type 19>;
type <type 25>;
type <type 28>;
type <type 41 "V0" = <type 4>>;
type <type 4>;
type <type 5>;
type <type 6>;


================================================
FILE: go/internal/gccgoimporter/testdata/complexnums.go
================================================
package complexnums

const NN = -1 - 1i
const NP = -1 + 1i
const PN = 1 - 1i
const PP = 1 + 1i


================================================
FILE: go/internal/gccgoimporter/testdata/complexnums.gox
================================================
v1;
package complexnums;
pkgpath complexnums;
priority 1;
const NN = -0.1E1-0.1E1i ;
const NP = -0.1E1+0.1E1i ;
const PN = 0.1E1-0.1E1i ;
const PP = 0.1E1+0.1E1i ;


================================================
FILE: go/internal/gccgoimporter/testdata/conversions.go
================================================
package conversions

type Units string

const Bits = Units("bits")


================================================
FILE: go/internal/gccgoimporter/testdata/conversions.gox
================================================
v2;
package conversions;
prefix go;
package conversions go.conversions go.conversions;
const Bits <type 1 "Units" <type -16>> = convert(<type 1>, "bits");
type <type 1>;


================================================
FILE: go/internal/gccgoimporter/testdata/escapeinfo.go
================================================
// Test case for escape info in export data. To compile and extract .gox file:
// gccgo -fgo-optimize-allocs -c escapeinfo.go
// objcopy -j .go_export escapeinfo.o escapeinfo.gox

package escapeinfo

type T struct{ data []byte }

func NewT(data []byte) *T {
	return &T{data}
}

func (*T) Read(p []byte) {}


================================================
FILE: go/internal/gccgoimporter/testdata/escapeinfo.gox
================================================
v2;
package escapeinfo;
prefix go;
package escapeinfo go.escapeinfo go.escapeinfo;
func NewT (data <type 1 [] <type -20>>) <type 2 *<type 3 "T" <type 4 struct { .go.escapeinfo.data <type 5 [] <type -20>>; }>
 func (? <type 6 *<type 3>>) Read (p <esc:0x1> <type 7 [] <type -20>>);
>>;
type <type 3>;
checksum 3500838130783C0059CD0C81527F60E9738E3ACE;


================================================
FILE: go/internal/gccgoimporter/testdata/imports.go
================================================
package imports

import "fmt"

var Hello = fmt.Sprintf("Hello, world")


================================================
FILE: go/internal/gccgoimporter/testdata/imports.gox
================================================
v1;
package imports;
pkgpath imports;
priority 7;
import fmt fmt "fmt";
init imports imports..import 7 math math..import 1 runtime runtime..import 1 strconv strconv..import 2 io io..import 3 reflect reflect..import 3 syscall syscall..import 3 time time..import 4 os os..import 5 fmt fmt..import 6;
var Hello <type -16>;


================================================
FILE: go/internal/gccgoimporter/testdata/issue27856.go
================================================
package lib

type M struct {
	E E
}
type F struct {
	_ *M
}
type E = F


================================================
FILE: go/internal/gccgoimporter/testdata/issue27856.gox
================================================
v2;
package main;
pkgpath main;
import runtime runtime "runtime";
init runtime runtime..import sys runtime_internal_sys..import;
init_graph 0 1;
type <type 1 "E" = <type 2 "F" <type 3 struct { .main._ <type 4 *<type 5 "M" <type 6 struct { E <type 1>; }>>>; }>>>;
type <type 2>;
type <type 5>;


================================================
FILE: go/internal/gccgoimporter/testdata/issue29198.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"errors"
)

type A struct {
	x int
}

func (a *A) AMethod(y int) *Server {
	return nil
}

// FooServer is a server that provides Foo services
type FooServer Server

func (f *FooServer) WriteEvents(ctx context.Context, x int) error {
	return errors.New("hey!")
}

type Server struct {
	FooServer *FooServer
	user      string
	ctx       context.Context
}

func New(sctx context.Context, u string) (*Server, error) {
	s := &Server{user: u, ctx: sctx}
	s.FooServer = (*FooServer)(s)
	return s, nil
}


================================================
FILE: go/internal/gccgoimporter/testdata/issue29198.gox
================================================
v2;
package server;
pkgpath issue29198;
import context context "context";
import errors errors "errors";
init context context..import fmt fmt..import poll internal_poll..import testlog internal_testlog..import io io..import os os..import reflect reflect..import runtime runtime..import sys runtime_internal_sys..import strconv strconv..import sync sync..import syscall syscall..import time time..import unicode unicode..import;
init_graph 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 0 10 0 11 0 12 0 13 1 2 1 3 1 4 1 5 1 6 1 7 1 8 1 9 1 10 1 11 1 12 1 13 2 4 2 7 2 8 2 10 2 11 2 12 4 7 4 8 4 10 5 2 5 3 5 4 5 7 5 8 5 10 5 11 5 12 6 7 6 8 6 9 6 10 6 13 7 8 9 7 9 8 10 7 10 8 11 7 11 8 11 10 12 7 12 8 12 10 12 11;
type <type 1 "A" <type 2 struct { .issue29198.x <type -11>; }>
 func (a <esc:0x1> <type 3 *<type 1>>) AMethod (y <type -11>) <type 4 *<type 5 "Server" <type 6 struct { FooServer <type 7 *<type 8 "FooServer" <type 5>
 func (f <esc:0x1> <type 9 *<type 8>>) WriteEvents (ctx <esc:0x1> <type 10 "context.Context" <type 11 interface { Deadline () (deadline <type 12 "time.Time" "time" <type 13 struct { .time.wall <type -8>; .time.ext <type -4>; .time.loc <type 14 *<type 15 "time.Location" <type 16 struct { .time.name <type -16>; .time.zone <type 17 [] <type 18 ".time.zone" <type 19 struct { .time.name <type -16>; .time.offset <type -11>; .time.isDST <type -15>; }>>>; .time.tx <type 20 [] <type 21 ".time.zoneTrans" <type 22 struct { .time.when <type -4>; .time.index <type -5>; .time.isstd <type -15>; .time.isutc <type -15>; }>>>; .time.cacheStart <type -4>; .time.cacheEnd <type -4>; .time.cacheZone <type 23 *<type 18>>; }>
 func (l <esc:0x22> <type 24 *<type 15>>) String () <type -16>;
 func (l <esc:0x1> <type 24>) .time.lookupFirstZone () <type -11>;
 func (l <esc:0x12> <type 24>) .time.get () <type 24>;
 func (l <esc:0x32> <type 24>) .time.lookup (sec <type -4>) (name <type -16>, offset <type -11>, isDST <type -15>, start <type -4>, end <type -4>);
 func (l <esc:0x1> <type 24>) .time.lookupName (name <esc:0x1> <type -16>, unix <type -4>) (offset <type -11>, ok <type -15>);
 func (l <esc:0x1> <type 24>) .time.firstZoneUsed () <type -15>;
>>; }>
 func (t <esc:0x12> <type 12>) In (loc <type 14>) <type 12>;
 func (t <esc:0x1> <type 12>) .time.date (full <type -15>) (year <type -11>, month <type 25 "time.Month" <type -11>
 func (m <type 25>) String () <type -16>;
>, day <type -11>, yday <type -11>);
 func (t <esc:0x1> <type 12>) Sub (u <esc:0x1> <type 12>) <type 26 "time.Duration" <type -4>
 func (d <type 26>) Truncate (m <type 26>) <type 26>;
 func (d <type 26>) String () <type -16>;
 func (d <type 26>) Round (m <type 26>) <type 26>;
 func (d <type 26>) Seconds () <type -10>;
 func (d <type 26>) Nanoseconds () <type -4>;
 func (d <type 26>) Minutes () <type -10>;
 func (d <type 26>) Hours () <type -10>;
>;
 func (t <esc:0x12> <type 12>) Add (d <type 26>) <type 12>;
 func (t <esc:0x12> <type 12>) UTC () <type 12>;
 func (t <type 12>) AddDate (years <type -11>, months <type -11>, days <type -11>) <type 12>;
 func (t <esc:0x1> <type 12>) MarshalBinary () (? <type 27 [] <type -20>>, ? <type -19>);
 func (t <esc:0x1> <type 12>) Nanosecond () <type -11>;
 func (t <esc:0x12> <type 12>) Round (d <type 26>) <type 12>;
 func (t <esc:0x1> <type 12>) Minute () <type -11>;
 func (t <esc:0x1> <type 12>) Clock () (hour <type -11>, min <type -11>, sec <type -11>);
 func (t <esc:0x1> <type 12>) ISOWeek () (year <type -11>, week <type -11>);
 func (t <esc:0x1> <type 12>) Day () <type -11>;
 func (t <esc:0x1> <type 28 *<type 12>>) .time.mono () <type -4>;
 func (t <esc:0x1> <type 12>) UnixNano () <type -4>;
 func (t <esc:0x1> <type 28>) .time.sec () <type -4>;
 func (t <esc:0x1> <type 12>) Second () <type -11>;
 func (t <esc:0x1> <type 12>) Before (u <esc:0x1> <type 12>) <type -15>;
 func (t <esc:0x1> <type 28>) UnmarshalBinary (data <esc:0x1> <type 29 [] <type -20>>) <type -19>;
 func (t <esc:0x1> <type 12>) Month () <type 25>;
 func (t <esc:0x1> <type 12>) YearDay () <type -11>;
 func (t <esc:0x12> <type 12>) Location () <type 14>;
 func (t <esc:0x32> <type 12>) Zone () (name <type -16>, offset <type -11>);
 func (t <esc:0x12> <type 12>) Local () <type 12>;
 func (t <esc:0x1> <type 28>) .time.setLoc (loc <type 14>);
 func (t <esc:0x12> <type 12>) Truncate (d <type 26>) <type 12>;
 func (t <esc:0x1> <type 12>) MarshalJSON () (? <type 30 [] <type -20>>, ? <type -19>);
 func (t <esc:0x1> <type 12>) AppendFormat (b <esc:0x12> <type 31 [] <type -20>>, layout <esc:0x1> <type -16>) <type 32 [] <type -20>>;
 func (t <esc:0x1> <type 28>) GobDecode (data <esc:0x1> <type 33 [] <type -20>>) <type -19>;
 func (t <esc:0x1> <type 28>) UnmarshalJSON (data <esc:0x1> <type 34 [] <type -20>>) <type -19>;
 func (t <esc:0x1> <type 12>) MarshalText () (? <type 35 [] <type -20>>, ? <type -19>);
 func (t <esc:0x1> <type 12>) GobEncode () (? <type 36 [] <type -20>>, ? <type -19>);
 func (t <esc:0x1> <type 28>) .time.stripMono ();
 func (t <esc:0x1> <type 12>) After (u <esc:0x1> <type 12>) <type -15>;
 func (t <esc:0x1> <type 12>) Hour () <type -11>;
 func (t <esc:0x1> <type 28>) UnmarshalText (data <esc:0x1> <type 37 [] <type -20>>) <type -19>;
 func (t <esc:0x1> <type 12>) Equal (u <esc:0x1> <type 12>) <type -15>;
 func (t <esc:0x1> <type 28>) .time.setMono (m <type -4>);
 func (t <esc:0x1> <type 12>) Year () <type -11>;
 func (t <esc:0x1> <type 12>) IsZero () <type -15>;
 func (t <esc:0x1> <type 28>) .time.addSec (d <type -4>);
 func (t <esc:0x1> <type 12>) Weekday () <type 38 "time.Weekday" <type -11>
 func (d <type 38>) String () <type -16>;
>;
 func (t <esc:0x1> <type 12>) String () <type -16>;
 func (t <esc:0x1> <type 28>) .time.nsec () <type -3>;
 func (t <esc:0x1> <type 12>) Format (layout <esc:0x1> <type -16>) <type -16>;
 func (t <esc:0x1> <type 28>) .time.unixSec () <type -4>;
 func (t <esc:0x1> <type 12>) Unix () <type -4>;
 func (t <esc:0x1> <type 12>) .time.abs () <type -8>;
 func (t <esc:0x32> <type 12>) .time.locabs () (name <type -16>, offset <type -11>, abs <type -8>);
 func (t <esc:0x1> <type 12>) Date () (year <type -11>, month <type 25>, day <type -11>);
>, ok <type -15>); Done () <type 39 chan <- <type 40 struct { }>>; Err () <type -19>; Value (key <type 41 interface { }>) <type 42 interface { }>; }>>, x <type -11>) <type -19>;
>>; .issue29198.user <type -16>; .issue29198.ctx <type 10>; }>>>;
>;
type <type 8>;
func New (sctx <type 10>, u <type -16>) (? <type 43 *<type 5>>, ? <type -19>);
type <type 5>;
checksum 86C8D76B2582F55A8BD2CA9E00060358EC1CE214;


================================================
FILE: go/internal/gccgoimporter/testdata/issue30628.go
================================================
package issue30628

import (
	"os"
	"sync"
)

const numR = int32(os.O_TRUNC + 5)

type Apple struct {
	hey sync.RWMutex
	x   int
	RQ  [numR]struct {
		Count    uintptr
		NumBytes uintptr
		Last     uintptr
	}
}


================================================
FILE: go/internal/gccgoimporter/testdata/issue30628.gox
================================================
v3;
package issue30628
pkgpath issue30628
import os os "os"
import sync sync "sync"
init cpu internal..z2fcpu..import poll internal..z2fpoll..import testlog internal..z2ftestlog..import io io..import os os..import runtime runtime..import sys runtime..z2finternal..z2fsys..import sync sync..import syscall syscall..import time time..import
init_graph 1 0 1 3 1 5 1 6 1 7 1 8 1 9 3 0 3 5 3 6 3 7 4 0 4 1 4 2 4 3 4 5 4 6 4 7 4 8 4 9 5 0 5 6 7 0 7 5 7 6 8 0 8 5 8 6 8 7 9 0 9 5 9 6 9 7 9 8
types 13 2 24 84 208 17 30 41 147 86 17 64 25 75
type 1 "Apple" <type 2>
type 2 struct { .issue30628.hey <type 3>; .issue30628.x <type -11>; RQ <type 11>; }
type 3 "sync.RWMutex" <type 7>
 func (rw <type 4>) Lock ()
 func (rw <esc:0x12> <type 4>) RLocker () ($ret8 <type 5>)
 func (rw <type 4>) RUnlock ()
 func (rw <type 4>) Unlock ()
 func (rw <type 4>) RLock ()
type 4 *<type 3>
type 5 "sync.Locker" <type 6>
type 6 interface { Lock (); Unlock (); }
type 7 struct { .sync.w <type 8>; .sync.writerSem <type -7>; .sync.readerSem <type -7>; .sync.readerCount <type -3>; .sync.readerWait <type -3>; }
type 8 "sync.Mutex" <type 10>
 func (m <type 9>) Unlock ()
 func (m <type 9>) Lock ()
type 9 *<type 8>
type 10 struct { .sync.state <type -3>; .sync.sema <type -7>; }
type 11 [517 ] <type 12>
type 12 struct { Count <type -13>; NumBytes <type -13>; Last <type -13>; }
checksum 199DCF6D3EE2FCF39F715B4E42B5F87F5B15D3AF


================================================
FILE: go/internal/gccgoimporter/testdata/issue31540.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package issue31540

type Y struct {
	q int
}

type Z map[int]int

type X = map[Y]Z

type A1 = X

type A2 = A1

type S struct {
	b int
	A2
}

func Hallo() S {
	return S{}
}


================================================
FILE: go/internal/gccgoimporter/testdata/issue31540.gox
================================================
v3;
package issue31540
pkgpath issue31540
types 11 7 23 23 20 22 20 21 57 31 45 36
type 1 "A1" = <type 4>
type 2 "A2" = <type 1>
type 3 "S" <type 7>
type 4 "X" = <type 8>
type 5 "Y" <type 9>
type 6 "Z" <type 10>
type 7 struct { .go.mapalias.b <type -11>; ? <type 2>; }
type 8 map [<type 5>] <type 6>
type 9 struct { .go.mapalias.q <type -11>; }
type 10 map [<type -11>] <type -11>
func Hallo () <type 3>
checksum C3FAF2524A90BC11225EE65D059BF27DFB69134B


================================================
FILE: go/internal/gccgoimporter/testdata/issue34182.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package issue34182

type T1 struct {
	f *T2
}

type T2 struct {
	f T3
}

type T3 struct {
	*T2
}


================================================
FILE: go/internal/gccgoimporter/testdata/issue34182.gox
================================================
v3;
package issue34182
pkgpath issue34182
init issue34182 ~go.issue34182
types 8 4 21 21 21 17 30 45 45
type 1 "T1" <type 6>
type 2 "T2" <type 7>
type 3 "T3" <type 5>
type 4 *<type 2>
type 5 struct { ? <type 4>; }
type 6 struct { .go.issue34182.f <type 4>; }
type 7 struct { .go.issue34182.f <type 3>; }
checksum FF02C49BAF44B06C087ED4E573F7CC880C79C208


================================================
FILE: go/internal/gccgoimporter/testdata/nointerface.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nointerface

type I int

//go:nointerface
func (p *I) Get() int { return int(*p) }

func (p *I) Set(v int) { *p = I(v) }


================================================
FILE: go/internal/gccgoimporter/testdata/nointerface.gox
================================================
v3;
package nointerface
pkgpath nointerface
types 3 2 133 17
type 1 "I" <type -11>
 func /*nointerface*/ (p <esc:0x1> <type 2>) Get () <type -11>
 func (p <esc:0x1> <type 2>) Set (v <type -11>)
type 2 *<type 1>


================================================
FILE: go/internal/gccgoimporter/testdata/notinheap.go
================================================
package notinheap

//go:notinheap
type S struct{}


================================================
FILE: go/internal/gccgoimporter/testdata/notinheap.gox
================================================
v3;
package notinheap
pkgpath notinheap
init notinheap ~notinheap
types 3 2 30 18
type 1 "S" notinheap <type 2>
type 2 struct { }


================================================
FILE: go/internal/gccgoimporter/testdata/pointer.go
================================================
package pointer

type Int8Ptr *int8


================================================
FILE: go/internal/gccgoimporter/testdata/pointer.gox
================================================
v1;
package pointer;
pkgpath pointer;
type <type 1 "Int8Ptr" <type 2 *<type -1>>>;


================================================
FILE: go/internal/gccgoimporter/testdata/time.gox
================================================
v2;
package time;
pkgpath time;
import errors errors "errors";
import sync sync "sync";
import syscall syscall "syscall";
init time time..import runtime runtime..import sync sync..import syscall syscall..import;
init_graph 0 1 0 2 0 3 2 1 3 1 3 2;
const ANSIC = "Mon Jan _2 15:04:05 2006";
func After (d <type 1 "Duration" <type -4>
 func (d <type 1>) String () <type -16>;
 func (d <type 1>) Nanoseconds () <type -4>;
 func (d <type 1>) Seconds () <type -10>;
 func (d <type 1>) Minutes () <type -10>;
 func (d <type 1>) Hours () <type -10>;
>) <type 2 chan <- <type 3 "Time" <type 4 struct { .time.sec <type -4>; .time.nsec <type -3>; .time.loc <type 5 *<type 6 "Location" <type 7 struct { .time.name <type -16>; .time.zone <type 8 [] <type 9 ".time.zone" <type 10 struct { .time.name <type -16>; .time.offset <type -11>; .time.isDST <type -15>; }>>>; .time.tx <type 11 [] <type 12 ".time.zoneTrans" <type 13 struct { .time.when <type -4>; .time.index <type -5>; .time.isstd <type -15>; .time.isutc <type -15>; }>>>; .time.cacheStart <type -4>; .time.cacheEnd <type -4>; .time.cacheZone <type 14 *<type 9>>; }>
 func (l <type 15 *<type 6>>) .time.get () <type 15>;
 func (l <type 15>) String () <type -16>;
 func (l <type 15>) .time.lookup (sec <type -4>) (name <type -16>, offset <type -11>, isDST <type -15>, start <type -4>, end <type -4>);
 func (l <type 15>) .time.lookupFirstZone () <type -11>;
 func (l <type 15>) .time.firstZoneUsed () <type -15>;
 func (l <type 15>) .time.lookupName (name <type -16>, unix <type -4>) (offset <type -11>, isDST <type -15>, ok <type -15>);
>>; }>
 func (t <type 3>) String () <type -16>;
 func (t <type 3>) Format (layout <type -16>) <type -16>;
 func (t <type 3>) AppendFormat (b <type 16 [] <type -20>>, layout <type -16>) <type 17 [] <type -20>>;
 func (t <type 3>) After (u <type 3>) <type -15>;
 func (t <type 3>) Before (u <type 3>) <type -15>;
 func (t <type 3>) Equal (u <type 3>) <type -15>;
 func (t <type 3>) IsZero () <type -15>;
 func (t <type 3>) .time.abs () <type -8>;
 func (t <type 3>) .time.locabs () (name <type -16>, offset <type -11>, abs <type -8>);
 func (t <type 3>) Date () (year <type -11>, month <type 18 "Month" <type -11>
 func (m <type 18>) String () <type -16>;
>, day <type -11>);
 func (t <type 3>) Year () <type -11>;
 func (t <type 3>) Month () <type 18>;
 func (t <type 3>) Day () <type -11>;
 func (t <type 3>) Weekday () <type 19 "Weekday" <type -11>
 func (d <type 19>) String () <type -16>;
>;
 func (t <type 3>) ISOWeek () (year <type -11>, week <type -11>);
 func (t <type 3>) Clock () (hour <type -11>, min <type -11>, sec <type -11>);
 func (t <type 3>) Hour () <type -11>;
 func (t <type 3>) Minute () <type -11>;
 func (t <type 3>) Second () <type -11>;
 func (t <type 3>) Nanosecond () <type -11>;
 func (t <type 3>) YearDay () <type -11>;
 func (t <type 3>) Add (d <type 1>) <type 3>;
 func (t <type 3>) Sub (u <type 3>) <type 1>;
 func (t <type 3>) AddDate (years <type -11>, months <type -11>, days <type -11>) <type 3>;
 func (t <type 3>) .time.date (full <type -15>) (year <type -11>, month <type 18>, day <type -11>, yday <type -11>);
 func (t <type 3>) UTC () <type 3>;
 func (t <type 3>) Local () <type 3>;
 func (t <type 3>) In (loc <type 20 *<type 6>>) <type 3>;
 func (t <type 3>) Location () <type 21 *<type 6>>;
 func (t <type 3>) Zone () (name <type -16>, offset <type -11>);
 func (t <type 3>) Unix () <type -4>;
 func (t <type 3>) UnixNano () <type -4>;
 func (t <type 3>) MarshalBinary () (? <type 22 [] <type -20>>, ? <type -19>);
 func (t <type 23 *<type 3>>) UnmarshalBinary (data <type 24 [] <type -20>>) <type -19>;
 func (t <type 3>) GobEncode () (? <type 25 [] <type -20>>, ? <type -19>);
 func (t <type 23>) GobDecode (data <type 26 [] <type -20>>) <type -19>;
 func (t <type 3>) MarshalJSON () (? <type 27 [] <type -20>>, ? <type -19>);
 func (t <type 23>) UnmarshalJSON (data <type 28 [] <type -20>>) <type -19>;
 func (t <type 3>) MarshalText () (? <type 29 [] <type -20>>, ? <type -19>);
 func (t <type 23>) UnmarshalText (data <type 30 [] <type -20>>) <type -19>;
 func (t <type 3>) Truncate (d <type 1>) <type 3>;
 func (t <type 3>) Round (d <type 1>) <type 3>;
>>;
func AfterFunc (d <type 1>, f <type 31 ()>) <type 32 *<type 33 "Timer" <type 34 struct { C <type 35 chan <- <type 3>>; .time.r <type 36 ".time.runtimeTimer" <type 37 struct { .time.i <type -11>; .time.when <type -4>; .time.period <type -4>; .time.f <type 38 (? <type 39 interface { }>, ? <type -13>)>; .time.arg <type 40 interface { }>; .time.seq <type -13>; }>>; }>
 func (t <type 41 *<type 33>>) Stop () <type -15>;
 func (t <type 41>) Reset (d <type 1>) <type -15>;
>>;
const April <type 18> = 4 ;
const August <type 18> = 8 ;
func Date (year <type -11>, month <type 18>, day <type -11>, hour <type -11>, min <type -11>, sec <type -11>, nsec <type -11>, loc <type 42 *<type 6>>) <type 3>;
const December <type 18> = 12 ;
type <type 1>;
const February <type 18> = 2 ;
func FixedZone (name <type -16>, offset <type -11>) <type 15>;
const Friday <type 19> = 5 ;
const Hour <type 1> = 3600000000000 ;
const January <type 18> = 1 ;
const July <type 18> = 7 ;
const June <type 18> = 6 ;
const Kitchen = "3:04PM";
func LoadLocation (name <type -16>) (? <type 15>, ? <type -19>);
var Local <type 15>;
type <type 6>;
var LocationSource <type 43 (name <type -16>) (? <type 44 [] <type -20>>, ? <type -19>)>;
const March <type 18> = 3 ;
const May <type 18> = 5 ;
const Microsecond <type 1> = 1000 ;
const Millisecond <type 1> = 1000000 ;
const Minute <type 1> = 60000000000 ;
const Monday <type 19> = 1 ;
type <type 18>;
const Nanosecond <type 1> = 1 ;
func NewTicker (d <type 1>) <type 45 *<type 46 "Ticker" <type 47 struct { C <type 48 chan <- <type 3>>; .time.r <type 36>; }>
 func (t <type 49 *<type 46>>) Stop ();
>>;
func NewTimer (d <type 1>) <type 32>;
const November <type 18> = 11 ;
func Now () <type 3>;
const October <type 18> = 10 ;
func Parse (layout <type -16>, value <type -16>) (? <type 3>, ? <type -19>);
func ParseDuration (s <type -16>) (? <type 1>, ? <type -19>);
type <type 50 "ParseError" <type 51 struct { Layout <type -16>; Value <type -16>; LayoutElem <type -16>; ValueElem <type -16>; Message <type -16>; }>
 func (e <type 52 *<type 50>>) Error () <type -16>;
>;
func ParseInLocation (layout <type -16>, value <type -16>, loc <type 53 *<type 6>>) (? <type 3>, ? <type -19>);
const RFC1123 = "Mon, 02 Jan 2006 15:04:05 MST";
const RFC1123Z = "Mon, 02 Jan 2006 15:04:05 -0700";
const RFC3339 = "2006-01-02T15:04:05Z07:00";
const RFC3339Nano = "2006-01-02T15:04:05.999999999Z07:00";
const RFC822 = "02 Jan 06 15:04 MST";
const RFC822Z = "02 Jan 06 15:04 -0700";
const RFC850 = "Monday, 02-Jan-06 15:04:05 MST";
const RubyDate = "Mon Jan 02 15:04:05 -0700 2006";
const Saturday <type 19> = 6 ;
const Second <type 1> = 1000000000 ;
const September <type 18> = 9 ;
func Since (t <type 3>) <type 1>;
func Sleep (d <type 1>);
const Stamp = "Jan _2 15:04:05";
const StampMicro = "Jan _2 15:04:05.000000";
const StampMilli = "Jan _2 15:04:05.000";
const StampNano = "Jan _2 15:04:05.000000000";
const Sunday <type 19> = 0 ;
const Thursday <type 19> = 4 ;
func Tick (d <type 1>) <type 54 chan <- <type 3>>;
type <type 46>;
type <type 3>;
type <type 33>;
const Tuesday <type 19> = 2 ;
var UTC <type 15>;
func Unix (sec <type -4>, nsec <type -4>) <type 3>;
const UnixDate = "Mon Jan _2 15:04:05 MST 2006";
const Wednesday <type 19> = 3 ;
type <type 19>;
checksum C04E7F45B20C621A25DC74E9B13EA4FF6732E226;


================================================
FILE: go/internal/gccgoimporter/testdata/unicode.gox
================================================
v2;
package unicode;
pkgpath unicode;
init unicode unicode..import;
var ASCII_Hex_Digit <type 1 *<type 2 "RangeTable" <type 3 struct { R16 <type 4 [] <type 5 "Range16" <type 6 struct { Lo <type -6>; Hi <type -6>; Stride <type -6>; }>>>; R32 <type 7 [] <type 8 "Range32" <type 9 struct { Lo <type -7>; Hi <type -7>; Stride <type -7>; }>>>; LatinOffset <type -11>; }>>>;
var Adlam <type 1>;
var Ahom <type 1>;
var Anatolian_Hieroglyphs <type 1>;
var Arabic <type 1>;
var Armenian <type 1>;
var Avestan <type 1>;
var AzeriCase <type 10 "SpecialCase" <type 11 [] <type 12 "CaseRange" <type 13 struct { Lo <type -7>; Hi <type -7>; Delta <type 14 ".unicode.d" <type 15 [3 ] <type -21>>>; }>>>
 func (special <type 10>) ToUpper (r <type -21>) <type -21>;
 func (special <type 10>) ToTitle (r <type -21>) <type -21>;
 func (special <type 10>) ToLower (r <type -21>) <type -21>;
>;
var Balinese <type 1>;
var Bamum <type 1>;
var Bassa_Vah <type 1>;
var Batak <type 1>;
var Bengali <type 1>;
var Bhaiksuki <type 1>;
var Bidi_Control <type 1>;
var Bopomofo <type 1>;
var Brahmi <type 1>;
var Braille <type 1>;
var Buginese <type 1>;
var Buhid <type 1>;
var C <type 1>;
var Canadian_Aboriginal <type 1>;
var Carian <type 1>;
type <type 12>;
var CaseRanges <type 16 [] <type 12>>;
var Categories <type 17 map [<type -16>] <type 1>>;
var Caucasian_Albanian <type 1>;
var Cc <type 1>;
var Cf <type 1>;
var Chakma <type 1>;
var Cham <type 1>;
var Cherokee <type 1>;
var Co <type 1>;
var Common <type 1>;
var Coptic <type 1>;
var Cs <type 1>;
var Cuneiform <type 1>;
var Cypriot <type 1>;
var Cyrillic <type 1>;
var Dash <type 1>;
var Deprecated <type 1>;
var Deseret <type 1>;
var Devanagari <type 1>;
var Diacritic <type 1>;
var Digit <type 1>;
var Duployan <type 1>;
var Egyptian_Hieroglyphs <type 1>;
var Elbasan <type 1>;
var Ethiopic <type 1>;
var Extender <type 1>;
var FoldCategory <type 18 map [<type -16>] <type 1>>;
var FoldScript <type 19 map [<type -16>] <type 1>>;
var Georgian <type 1>;
var Glagolitic <type 1>;
var Gothic <type 1>;
var Grantha <type 1>;
var GraphicRanges <type 20 [] <type 21 *<type 2>>>;
var Greek <type 1>;
var Gujarati <type 1>;
var Gurmukhi <type 1>;
var Han <type 1>;
var Hangul <type 1>;
var Hanunoo <type 1>;
var Hatran <type 1>;
var Hebrew <type 1>;
var Hex_Digit <type 1>;
var Hiragana <type 1>;
var Hyphen <type 1>;
var IDS_Binary_Operator <type 1>;
var IDS_Trinary_Operator <type 1>;
var Ideographic <type 1>;
var Imperial_Aramaic <type 1>;
func In (r <type -21>, ranges ...<type 22 *<type 2>>) <type -15>;
var Inherited <type 1>;
var Inscriptional_Pahlavi <type 1>;
var Inscriptional_Parthian <type 1>;
func Is (rangeTab <type 1>, r <type -21>) <type -15>;
func IsControl (r <type -21>) <type -15>;
func IsDigit (r <type -21>) <type -15>;
func IsGraphic (r <type -21>) <type -15>;
func IsLetter (r <type -21>) <type -15>;
func IsLower (r <type -21>) <type -15>;
func IsMark (r <type -21>) <type -15>;
func IsNumber (r <type -21>) <type -15>;
func IsOneOf (ranges <type 23 [] <type 24 *<type 2>>>, r <type -21>) <type -15>;
func IsPrint (r <type -21>) <type -15>;
func IsPunct (r <type -21>) <type -15>;
func IsSpace (r <type -21>) <type -15>;
func IsSymbol (r <type -21>) <type -15>;
func IsTitle (r <type -21>) <type -15>;
func IsUpper (r <type -21>) <type -15>;
var Javanese <type 1>;
var Join_Control <type 1>;
var Kaithi <type 1>;
var Kannada <type 1>;
var Katakana <type 1>;
var Kayah_Li <type 1>;
var Kharoshthi <type 1>;
var Khmer <type 1>;
var Khojki <type 1>;
var Khudawadi <type 1>;
var L <type 1>;
var Lao <type 1>;
var Latin <type 1>;
var Lepcha <type 1>;
var Letter <type 1>;
var Limbu <type 1>;
var Linear_A <type 1>;
var Linear_B <type 1>;
var Lisu <type 1>;
var Ll <type 1>;
var Lm <type 1>;
var Lo <type 1>;
var Logical_Order_Exception <type 1>;
var Lower <type 1>;
const LowerCase = 1 ;
var Lt <type 1>;
var Lu <type 1>;
var Lycian <type 1>;
var Lydian <type 1>;
var M <type 1>;
var Mahajani <type 1>;
var Malayalam <type 1>;
var Mandaic <type 1>;
var Manichaean <type 1>;
var Marchen <type 1>;
var Mark <type 1>;
const MaxASCII = 127' ;
const MaxCase = 3 ;
const MaxLatin1 = 255' ;
const MaxRune = 1114111' ;
var Mc <type 1>;
var Me <type 1>;
var Meetei_Mayek <type 1>;
var Mende_Kikakui <type 1>;
var Meroitic_Cursive <type 1>;
var Meroitic_Hieroglyphs <type 1>;
var Miao <type 1>;
var Mn <type 1>;
var Modi <type 1>;
var Mongolian <type 1>;
var Mro <type 1>;
var Multani <type 1>;
var Myanmar <type 1>;
var N <type 1>;
var Nabataean <type 1>;
var Nd <type 1>;
var New_Tai_Lue <type 1>;
var Newa <type 1>;
var Nko <type 1>;
var Nl <type 1>;
var No <type 1>;
var Noncharacter_Code_Point <type 1>;
var Number <type 1>;
var Ogham <type 1>;
var Ol_Chiki <type 1>;
var Old_Hungarian <type 1>;
var Old_Italic <type 1>;
var Old_North_Arabian <type 1>;
var Old_Permic <type 1>;
var Old_Persian <type 1>;
var Old_South_Arabian <type 1>;
var Old_Turkic <type 1>;
var Oriya <type 1>;
var Osage <type 1>;
var Osmanya <type 1>;
var Other <type 1>;
var Other_Alphabetic <type 1>;
var Other_Default_Ignorable_Code_Point <type 1>;
var Other_Grapheme_Extend <type 1>;
var Other_ID_Continue <type 1>;
var Other_ID_Start <type 1>;
var Other_Lowercase <type 1>;
var Other_Math <type 1>;
var Other_Uppercase <type 1>;
var P <type 1>;
var Pahawh_Hmong <type 1>;
var Palmyrene <type 1>;
var Pattern_Syntax <type 1>;
var Pattern_White_Space <type 1>;
var Pau_Cin_Hau <type 1>;
var Pc <type 1>;
var Pd <type 1>;
var Pe <type 1>;
var Pf <type 1>;
var Phags_Pa <type 1>;
var Phoenician <type 1>;
var Pi <type 1>;
var Po <type 1>;
var Prepended_Concatenation_Mark <type 1>;
var PrintRanges <type 25 [] <type 26 *<type 2>>>;
var Properties <type 27 map [<type -16>] <type 1>>;
var Ps <type 1>;
var Psalter_Pahlavi <type 1>;
var Punct <type 1>;
var Quotation_Mark <type 1>;
var Radical <type 1>;
type <type 5>;
type <type 8>;
type <type 2>;
var Rejang <type 1>;
const ReplacementChar = 65533' ;
var Runic <type 1>;
var S <type 1>;
var STerm <type 1>;
var Samaritan <type 1>;
var Saurashtra <type 1>;
var Sc <type 1>;
var Scripts <type 28 map [<type -16>] <type 1>>;
var Sentence_Terminal <type 1>;
var Sharada <type 1>;
var Shavian <type 1>;
var Siddham <type 1>;
var SignWriting <type 1>;
func SimpleFold (r <type -21>) <type -21>;
var Sinhala <type 1>;
var Sk <type 1>;
var Sm <type 1>;
var So <type 1>;
var Soft_Dotted <type 1>;
var Sora_Sompeng <type 1>;
var Space <type 1>;
type <type 10>;
var Sundanese <type 1>;
var Syloti_Nagri <type 1>;
var Symbol <type 1>;
var Syriac <type 1>;
var Tagalog <type 1>;
var Tagbanwa <type 1>;
var Tai_Le <type 1>;
var Tai_Tham <type 1>;
var Tai_Viet <type 1>;
var Takri <type 1>;
var Tamil <type 1>;
var Tangut <type 1>;
var Telugu <type 1>;
var Terminal_Punctuation <type 1>;
var Thaana <type 1>;
var Thai <type 1>;
var Tibetan <type 1>;
var Tifinagh <type 1>;
var Tirhuta <type 1>;
var Title <type 1>;
const TitleCase = 2 ;
func To (_case <type -11>, r <type -21>) <type -21>;
func ToLower (r <type -21>) <type -21>;
func ToTitle (r <type -21>) <type -21>;
func ToUpper (r <type -21>) <type -21>;
var TurkishCase <type 10>;
var Ugaritic <type 1>;
var Unified_Ideograph <type 1>;
var Upper <type 1>;
const UpperCase = 0 ;
const UpperLower = 1114112' ;
var Vai <type 1>;
var Variation_Selector <type 1>;
const Version = "9.0.0";
var Warang_Citi <type 1>;
var White_Space <type 1>;
var Yi <type 1>;
var Z <type 1>;
var Zl <type 1>;
var Zp <type 1>;
var Zs <type 1>;
checksum 7643975C0BE2732C7557F1B2A70796673C11DF4A;


================================================
FILE: go/internal/gccgoimporter/testdata/v1reflect.gox
================================================
v1;
package reflect;
pkgpath reflect;
priority 3;
import math math "math";
import runtime runtime "runtime";
import strconv strconv "strconv";
import sync sync "sync";
import unsafe unsafe "unsafe";
init reflect reflect..import 3 math math..import 1 runtime runtime..import 1 strconv strconv..import 2;
func Append (s <type 1 "Value" <type 2 struct { .reflect.typ <type 3 *<type 4 ".reflect.commonType" <type 5 struct { .reflect.kind <type -5>; .reflect.align <type -1>; .reflect.fieldAlign <type -5>; .reflect._ <type -5>; .reflect.size <type -13>; .reflect.hash <type -7>; .reflect.hashfn <type 6 (? <type 7 "unsafe.Pointer" <type 8 *any>>, ? <type -13>)>; .reflect.equalfn <type 9 (? <type 7>, ? <type 7>, ? <type -13>)>; .reflect.string <type 10 *<type -16>>; ? <type 11 *<type 12 ".reflect.uncommonType" <type 13 struct { .reflect.name <type 14 *<type -16>>; .reflect.pkgPath <type 15 *<type -16>>; .reflect.methods <type 16 [] <type 17 ".reflect.method" <type 18 struct { .reflect.name <type 19 *<type -16>>; .reflect.pkgPath <type 20 *<type -16>>; .reflect.mtyp <type 21 *<type 22 ".reflect.runtimeType" <type 4>>>; .reflect.typ <type 21>; .reflect.tfn <type 7>; }>>>; }>
 func (t <type 23 *<type 12>>) .reflect.uncommon () <type 23>;
 func (t <type 23>) PkgPath () <type -16>;
 func (t <type 23>) Name () <type -16>;
 func (t <type 23>) Method (i <type -11>) (m <type 24 "Method" <type 25 struct { Name <type -16>; PkgPath <type -16>; Type <type 26 "Type" <type 27 interface { Align () <type -11>; FieldAlign () <type -11>; Method (? <type -11>) <type 24>; MethodByName (? <type -16>) (? <type 24>, ? <type -15>); NumMethod () <type -11>; Name () <type -16>; PkgPath () <type -16>; Size () <type -13>; String () <type -16>; .reflect.rawString () <type -16>; Kind () <type 28 "Kind" <type -12>
 func (k <type 28>) String () <type -16>;
>; Implements (u <type 26>) <type -15>; AssignableTo (u <type 26>) <type -15>; Bits () <type -11>; ChanDir () <type 29 "ChanDir" <type -11>
 func (d <type 29>) String () <type -16>;
>; IsVariadic () <type -15>; Elem () <type 26>; Field (i <type -11>) <type 30 "StructField" <type 31 struct { Name <type -16>; PkgPath <type -16>; Type <type 26>; Tag <type 32 "StructTag" <type -16>
 func (tag <type 32>) Get (key <type -16>) <type -16>;
>; Offset <type -13>; Index <type 33 [] <type -11>>; Anonymous <type -15>; }>>; FieldByIndex (index <type 34 [] <type -11>>) <type 30>; FieldByName (name <type -16>) (? <type 30>, ? <type -15>); FieldByNameFunc (match <type 35 (? <type -16>) <type -15>>) (? <type 30>, ? <type -15>); In (i <type -11>) <type 26>; Key () <type 26>; Len () <type -11>; NumField () <type -11>; NumIn () <type -11>; NumOut () <type -11>; Out (i <type -11>) <type 26>; .reflect.runtimeType () <type 36 *<type 22>>; .reflect.common () <type 37 *<type 4>>; .reflect.uncommon () <type 38 *<type 12>>; }>>; Func <type 1>; Index <type -11>; }>>);
 func (t <type 23>) NumMethod () <type -11>;
 func (t <type 23>) MethodByName (name <type -16>) (m <type 24>, ok <type -15>);
>>; .reflect.ptrToThis <type 21>; }>
 func (t <type 39 *<type 4>>) .reflect.toType () <type 26>;
 func (t <type 39>) .reflect.rawString () <type -16>;
 func (t <type 39>) String () <type -16>;
 func (t <type 39>) Size () <type -13>;
 func (t <type 39>) Bits () <type -11>;
 func (t <type 39>) Align () <type -11>;
 func (t <type 39>) FieldAlign () <type -11>;
 func (t <type 39>) Kind () <type 28>;
 func (t <type 39>) .reflect.common () <type 39>;
 func (t <type 39>) NumMethod () <type -11>;
 func (t <type 39>) Method (i <type -11>) (m <type 24>);
 func (t <type 39>) MethodByName (name <type -16>) (m <type 24>, ok <type -15>);
 func (t <type 39>) PkgPath () <type -16>;
 func (t <type 39>) Name () <type -16>;
 func (t <type 39>) ChanDir () <type 29>;
 func (t <type 39>) IsVariadic () <type -15>;
 func (t <type 39>) Elem () <type 26>;
 func (t <type 39>) Field (i <type -11>) <type 30>;
 func (t <type 39>) FieldByIndex (index <type 40 [] <type -11>>) <type 30>;
 func (t <type 39>) FieldByName (name <type -16>) (? <type 30>, ? <type -15>);
 func (t <type 39>) FieldByNameFunc (match <type 41 (? <type -16>) <type -15>>) (? <type 30>, ? <type -15>);
 func (t <type 39>) In (i <type -11>) <type 26>;
 func (t <type 39>) Key () <type 26>;
 func (t <type 39>) Len () <type -11>;
 func (t <type 39>) NumField () <type -11>;
 func (t <type 39>) NumIn () <type -11>;
 func (t <type 39>) NumOut () <type -11>;
 func (t <type 39>) Out (i <type -11>) <type 26>;
 func (t <type 39>) .reflect.runtimeType () <type 21>;
 func (ct <type 39>) .reflect.ptrTo () <type 39>;
 func (t <type 39>) Implements (u <type 26>) <type -15>;
 func (t <type 39>) AssignableTo (u <type 26>) <type -15>;
>>; .reflect.val <type 7>; ? <type 42 ".reflect.flag" <type -13>
 func (f <type 42>) .reflect.kind () <type 28>;
 func (f <type 42>) .reflect.mustBe (expected <type 28>);
 func (f <type 42>) .reflect.mustBeExported ();
 func (f <type 42>) .reflect.mustBeAssignable ();
>; }>
 func (v <type 1>) .reflect.iword () <type 43 ".reflect.iword" <type 7>>;
 func (v <type 1>) Addr () <type 1>;
 func (v <type 1>) Bool () <type -15>;
 func (v <type 1>) Bytes () <type 44 [] <type -20>>;
 func (v <type 1>) CanAddr () <type -15>;
 func (v <type 1>) CanSet () <type -15>;
 func (v <type 1>) Call (in <type 45 [] <type 1>>) <type 46 [] <type 1>>;
 func (v <type 1>) CallSlice (in <type 47 [] <type 1>>) <type 48 [] <type 1>>;
 func (v <type 1>) .reflect.call (method <type -16>, in <type 49 [] <type 1>>) <type 50 [] <type 1>>;
 func (v <type 1>) Cap () <type -11>;
 func (v <type 1>) Close ();
 func (v <type 1>) Complex () <type -18>;
 func (v <type 1>) Elem () <type 1>;
 func (v <type 1>) Field (i <type -11>) <type 1>;
 func (v <type 1>) FieldByIndex (index <type 51 [] <type -11>>) <type 1>;
 func (v <type 1>) FieldByName (name <type -16>) <type 1>;
 func (v <type 1>) FieldByNameFunc (match <type 52 (? <type -16>) <type -15>>) <type 1>;
 func (v <type 1>) Float () <type -10>;
 func (v <type 1>) Index (i <type -11>) <type 1>;
 func (v <type 1>) Int () <type -4>;
 func (v <type 1>) CanInterface () <type -15>;
 func (v <type 1>) Interface () (i <type 53 interface { }>);
 func (v <type 1>) InterfaceData () <type 54 [2 ] <type -13>>;
 func (v <type 1>) IsNil () <type -15>;
 func (v <type 1>) IsValid () <type -15>;
 func (v <type 1>) Kind () <type 28>;
 func (v <type 1>) Len () <type -11>;
 func (v <type 1>) MapIndex (key <type 1>) <type 1>;
 func (v <type 1>) MapKeys () <type 55 [] <type 1>>;
 func (v <type 1>) Method (i <type -11>) <type 1>;
 func (v <type 1>) NumMethod () <type -11>;
 func (v <type 1>) MethodByName (name <type -16>) <type 1>;
 func (v <type 1>) NumField () <type -11>;
 func (v <type 1>) OverflowComplex (x <type -18>) <type -15>;
 func (v <type 1>) OverflowFloat (x <type -10>) <type -15>;
 func (v <type 1>) OverflowInt (x <type -4>) <type -15>;
 func (v <type 1>) OverflowUint (x <type -8>) <type -15>;
 func (v <type 1>) Pointer () <type -13>;
 func (v <type 1>) Recv () (x <type 1>, ok <type -15>);
 func (v <type 1>) .reflect.recv (nb <type -15>) (val <type 1>, ok <type -15>);
 func (v <type 1>) Send (x <type 1>);
 func (v <type 1>) .reflect.send (x <type 1>, nb <type -15>) (selected <type -15>);
 func (v <type 1>) Set (x <type 1>);
 func (v <type 1>) SetBool (x <type -15>);
 func (v <type 1>) SetBytes (x <type 56 [] <type -20>>);
 func (v <type 1>) SetComplex (x <type -18>);
 func (v <type 1>) SetFloat (x <type -10>);
 func (v <type 1>) SetInt (x <type -4>);
 func (v <type 1>) SetLen (n <type -11>);
 func (v <type 1>) SetMapIndex (key <type 1>, val <type 1>);
 func (v <type 1>) SetUint (x <type -8>);
 func (v <type 1>) SetPointer (x <type 7>);
 func (v <type 1>) SetString (x <type -16>);
 func (v <type 1>) Slice (beg <type -11>, end <type -11>) <type 1>;
 func (v <type 1>) String () <type -16>;
 func (v <type 1>) TryRecv () (x <type 1>, ok <type -15>);
 func (v <type 1>) TrySend (x <type 1>) <type -15>;
 func (v <type 1>) Type () <type 26>;
 func (v <type 1>) Uint () <type -8>;
 func (v <type 1>) UnsafeAddr () <type -13>;
 func (v <type 1>) .reflect.assignTo (context <type -16>, dst <type 3>, target <type 57 *<type 58 interface { }>>) <type 1>;
>, x ...<type 1>) <type 1>;
func AppendSlice (s <type 1>, t <type 1>) <type 1>;
const Array <type 28> = 17 ;
const Bool <type 28> = 1 ;
const BothDir <type 29> = 3 ;
const Chan <type 28> = 18 ;
type <type 29>;
const Complex128 <type 28> = 16 ;
const Complex64 <type 28> = 15 ;
func Copy (dst <type 1>, src <type 1>) <type -11>;
func DeepEqual (a1 <type 59 interface { }>, a2 <type 59>) <type -15>;
const Float32 <type 28> = 13 ;
const Float64 <type 28> = 14 ;
const Func <type 28> = 19 ;
func Indirect (v <type 1>) <type 1>;
const Int <type 28> = 2 ;
const Int16 <type 28> = 4 ;
const Int32 <type 28> = 5 ;
const Int64 <type 28> = 6 ;
const Int8 <type 28> = 3 ;
const Interface <type 28> = 20 ;
const Invalid <type 28> = 0 ;
type <type 28>;
func MakeChan (typ <type 26>, buffer <type -11>) <type 1>;
func MakeMap (typ <type 26>) <type 1>;
func MakeSlice (typ <type 26>, len <type -11>, cap <type -11>) <type 1>;
const Map <type 28> = 21 ;
type <type 24>;
func Method$equal (key1 <type 8>, key2 <type 8>, key_size <type -13>) <type -15>;
func Method$hash (key <type 8>, key_size <type -13>) <type -13>;
func New (typ <type 26>) <type 1>;
func NewAt (typ <type 26>, p <type 7>) <type 1>;
const Ptr <type 28> = 22 ;
func PtrTo (t <type 26>) <type 26>;
const RecvDir <type 29> = 1 ;
const SendDir <type 29> = 2 ;
const Slice <type 28> = 23 ;
type <type 60 "SliceHeader" <type 61 struct { Data <type -13>; Len <type -11>; Cap <type -11>; }>>;
const String <type 28> = 24 ;
type <type 62 "StringHeader" <type 63 struct { Data <type -13>; Len <type -11>; }>>;
const Struct <type 28> = 25 ;
type <type 30>;
type <type 32>;
type <type 26>;
func TypeOf (i <type 64 interface { }>) <type 26>;
const Uint <type 28> = 7 ;
const Uint16 <type 28> = 9 ;
const Uint32 <type 28> = 10 ;
const Uint64 <type 28> = 11 ;
const Uint8 <type 28> = 8 ;
const Uintptr <type 28> = 12 ;
const UnsafePointer <type 28> = 26 ;
type <type 1>;
type <type 65 "ValueError" <type 66 struct { Method <type -16>; Kind <type 28>; }>
 func (e <type 67 *<type 65>>) Error () <type -16>;
>;
func ValueError$equal (key1 <type 8>, key2 <type 8>, key_size <type -13>) <type -15>;
func ValueError$hash (key <type 8>, key_size <type -13>) <type -13>;
func ValueOf (i <type 68 interface { }>) <type 1>;
func Zero (typ <type 26>) <type 1>;
checksum DD7720796E91D9D24ED12B75BDEA2A714D47B095;


================================================
FILE: go/internal/gccgoimporter/testenv_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains testing utilities copied from $GOROOT/src/internal/testenv/testenv.go.

package gccgoimporter

import (
	"runtime"
	"testing"

	toolstestenv "golang.org/x/tools/internal/testenv"
)

// HasExec reports whether the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
func HasExec() bool {
	return toolstestenv.HasExec()
}

// MustHaveExec checks that the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
// If not, MustHaveExec calls t.Skip with an explanation.
func MustHaveExec(t *testing.T) {
	if !HasExec() {
		t.Skipf("skipping test: cannot exec subprocess on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

var testenv = struct {
	MustHaveExec func(*testing.T)
}{
	MustHaveExec: MustHaveExec,
}


================================================
FILE: go/loader/doc.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package loader loads a complete Go program from source code, parsing
// and type-checking the initial packages plus their transitive closure
// of dependencies.  The ASTs and the derived facts are retained for
// later use.
//
// Deprecated: This is an older API and does not have support
// for modules. Use golang.org/x/tools/go/packages instead.
//
// The package defines two primary types: Config, which specifies a
// set of initial packages to load and various other options; and
// Program, which is the result of successfully loading the packages
// specified by a configuration.
//
// The configuration can be set directly, but *Config provides various
// convenience methods to simplify the common cases, each of which can
// be called any number of times.  Finally, these are followed by a
// call to Load() to actually load and type-check the program.
//
//	var conf loader.Config
//
//	// Use the command-line arguments to specify
//	// a set of initial packages to load from source.
//	// See FromArgsUsage for help.
//	rest, err := conf.FromArgs(os.Args[1:], wantTests)
//
//	// Parse the specified files and create an ad hoc package with path "foo".
//	// All files must have the same 'package' declaration.
//	conf.CreateFromFilenames("foo", "foo.go", "bar.go")
//
//	// Create an ad hoc package with path "foo" from
//	// the specified already-parsed files.
//	// All ASTs must have the same 'package' declaration.
//	conf.CreateFromFiles("foo", parsedFiles)
//
//	// Add "runtime" to the set of packages to be loaded.
//	conf.Import("runtime")
//
//	// Adds "fmt" and "fmt_test" to the set of packages
//	// to be loaded.  "fmt" will include *_test.go files.
//	conf.ImportWithTests("fmt")
//
//	// Finally, load all the packages specified by the configuration.
//	prog, err := conf.Load()
//
// See examples_test.go for examples of API usage.
//
// # CONCEPTS AND TERMINOLOGY
//
// The WORKSPACE is the set of packages accessible to the loader.  The
// workspace is defined by Config.Build, a *build.Context.  The
// default context treats subdirectories of $GOROOT and $GOPATH as
// packages, but this behavior may be overridden.
//
// An AD HOC package is one specified as a set of source files on the
// command line.  In the simplest case, it may consist of a single file
// such as $GOROOT/src/net/http/triv.go.
//
// EXTERNAL TEST packages are those comprised of a set of *_test.go
// files all with the same 'package foo_test' declaration, all in the
// same directory.  (go/build.Package calls these files XTestFiles.)
//
// An IMPORTABLE package is one that can be referred to by some import
// spec.  Every importable package is uniquely identified by its
// PACKAGE PATH or just PATH, a string such as "fmt", "encoding/json",
// or "cmd/vendor/golang.org/x/arch/x86/x86asm".  A package path
// typically denotes a subdirectory of the workspace.
//
// An import declaration uses an IMPORT PATH to refer to a package.
// Most import declarations use the package path as the import path.
//
// Due to VENDORING (https://golang.org/s/go15vendor), the
// interpretation of an import path may depend on the directory in which
// it appears.  To resolve an import path to a package path, go/build
// must search the enclosing directories for a subdirectory named
// "vendor".
//
// ad hoc packages and external test packages are NON-IMPORTABLE.  The
// path of an ad hoc package is inferred from the package
// declarations of its files and is therefore not a unique package key.
// For example, Config.CreatePkgs may specify two initial ad hoc
// packages, both with path "main".
//
// An AUGMENTED package is an importable package P plus all the
// *_test.go files with same 'package foo' declaration as P.
// (go/build.Package calls these files TestFiles.)
//
// The INITIAL packages are those specified in the configuration.  A
// DEPENDENCY is a package loaded to satisfy an import in an initial
// package or another dependency.
package loader

// IMPLEMENTATION NOTES
//
// 'go test', in-package test files, and import cycles
// ---------------------------------------------------
//
// An external test package may depend upon members of the augmented
// package that are not in the unaugmented package, such as functions
// that expose internals.  (See bufio/export_test.go for an example.)
// So, the loader must ensure that for each external test package
// it loads, it also augments the corresponding non-test package.
//
// The import graph over n unaugmented packages must be acyclic; the
// import graph over n-1 unaugmented packages plus one augmented
// package must also be acyclic.  ('go test' relies on this.)  But the
// import graph over n augmented packages may contain cycles.
//
// First, all the (unaugmented) non-test packages and their
// dependencies are imported in the usual way; the loader reports an
// error if it detects an import cycle.
//
// Then, each package P for which testing is desired is augmented by
// the list P' of its in-package test files, by calling
// (*types.Checker).Files.  This arrangement ensures that P' may
// reference definitions within P, but P may not reference definitions
// within P'.  Furthermore, P' may import any other package, including
// ones that depend upon P, without an import cycle error.
//
// Consider two packages A and B, both of which have lists of
// in-package test files we'll call A' and B', and which have the
// following import graph edges:
//    B  imports A
//    B' imports A
//    A' imports B
// This last edge would be expected to create an error were it not
// for the special type-checking discipline above.
// Cycles of size greater than two are possible.  For example:
//   compress/bzip2/bzip2_test.go (package bzip2)  imports "io/ioutil"
//   io/ioutil/tempfile_test.go   (package ioutil) imports "regexp"
//   regexp/exec_test.go          (package regexp) imports "compress/bzip2"
//
//
// Concurrency
// -----------
//
// Let us define the import dependency graph as follows.  Each node is a
// list of files passed to (Checker).Files at once.  Many of these lists
// are the production code of an importable Go package, so those nodes
// are labelled by the package's path.  The remaining nodes are
// ad hoc packages and lists of in-package *_test.go files that augment
// an importable package; those nodes have no label.
//
// The edges of the graph represent import statements appearing within a
// file.  An edge connects a node (a list of files) to the node it
// imports, which is importable and thus always labelled.
//
// Loading is controlled by this dependency graph.
//
// To reduce I/O latency, we start loading a package's dependencies
// asynchronously as soon as we've parsed its files and enumerated its
// imports (scanImports).  This performs a preorder traversal of the
// import dependency graph.
//
// To exploit hardware parallelism, we type-check unrelated packages in
// parallel, where "unrelated" means not ordered by the partial order of
// the import dependency graph.
//
// We use a concurrency-safe non-blocking cache (importer.imported) to
// record the results of type-checking, whether success or failure.  An
// entry is created in this cache by startLoad the first time the
// package is imported.  The first goroutine to request an entry becomes
// responsible for completing the task and broadcasting completion to
// subsequent requesters, which block until then.
//
// Type checking occurs in (parallel) postorder: we cannot type-check a
// set of files until we have loaded and type-checked all of their
// immediate dependencies (and thus all of their transitive
// dependencies). If the input were guaranteed free of import cycles,
// this would be trivial: we could simply wait for completion of the
// dependencies and then invoke the typechecker.
//
// But as we saw in the 'go test' section above, some cycles in the
// import graph over packages are actually legal, so long as the
// cycle-forming edge originates in the in-package test files that
// augment the package.  This explains why the nodes of the import
// dependency graph are not packages, but lists of files: the unlabelled
// nodes avoid the cycles.  Consider packages A and B where B imports A
// and A's in-package tests AT import B.  The naively constructed import
// graph over packages would contain a cycle (A+AT) --> B --> (A+AT) but
// the graph over lists of files is AT --> B --> A, where AT is an
// unlabelled node.
//
// Awaiting completion of the dependencies in a cyclic graph would
// deadlock, so we must materialize the import dependency graph (as
// importer.graph) and check whether each import edge forms a cycle.  If
// x imports y, and the graph already contains a path from y to x, then
// there is an import cycle, in which case the processing of x must not
// wait for the completion of processing of y.
//
// When the type-checker makes a callback (doImport) to the loader for a
// given import edge, there are two possible cases.  In the normal case,
// the dependency has already been completely type-checked; doImport
// does a cache lookup and returns it.  In the cyclic case, the entry in
// the cache is still necessarily incomplete, indicating a cycle.  We
// perform the cycle check again to obtain the error message, and return
// the error.
//
// The result of using concurrency is about a 2.5x speedup for stdlib_test.


================================================
FILE: go/loader/loader.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package loader

// See doc.go for package documentation and implementation notes.

import (
	"errors"
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/internal/cgo"
)

var ignoreVendor build.ImportMode

const trace = false // show timing info for type-checking

// Config specifies the configuration for loading a whole program from
// Go source code.
// The zero value for Config is a ready-to-use default configuration.
type Config struct {
	// Fset is the file set for the parser to use when loading the
	// program.  If nil, it may be lazily initialized by any
	// method of Config.
	Fset *token.FileSet

	// ParserMode specifies the mode to be used by the parser when
	// loading source packages.
	ParserMode parser.Mode

	// TypeChecker contains options relating to the type checker.
	//
	// The supplied IgnoreFuncBodies is not used; the effective
	// value comes from the TypeCheckFuncBodies func below.
	// The supplied Import function is not used either.
	TypeChecker types.Config

	// TypeCheckFuncBodies is a predicate over package paths.
	// A package for which the predicate is false will
	// have its package-level declarations type checked, but not
	// its function bodies; this can be used to quickly load
	// dependencies from source.  If nil, all func bodies are type
	// checked.
	TypeCheckFuncBodies func(path string) bool

	// If Build is non-nil, it is used to locate source packages.
	// Otherwise &build.Default is used.
	//
	// By default, cgo is invoked to preprocess Go files that
	// import the fake package "C".  This behaviour can be
	// disabled by setting CGO_ENABLED=0 in the environment prior
	// to startup, or by setting Build.CgoEnabled=false.
	Build *build.Context

	// The current directory, used for resolving relative package
	// references such as "./go/loader".  If empty, os.Getwd will be
	// used instead.
	Cwd string

	// If DisplayPath is non-nil, it is used to transform each
	// file name obtained from Build.Import().  This can be used
	// to prevent a virtualized build.Config's file names from
	// leaking into the user interface.
	DisplayPath func(path string) string

	// If AllowErrors is true, Load will return a Program even
	// if some of the its packages contained I/O, parser or type
	// errors; such errors are accessible via PackageInfo.Errors.  If
	// false, Load will fail if any package had an error.
	AllowErrors bool

	// CreatePkgs specifies a list of non-importable initial
	// packages to create.  The resulting packages will appear in
	// the corresponding elements of the Program.Created slice.
	CreatePkgs []PkgSpec

	// ImportPkgs specifies a set of initial packages to load.
	// The map keys are package paths.
	//
	// The map value indicates whether to load tests.  If true, Load
	// will add and type-check two lists of files to the package:
	// non-test files followed by in-package *_test.go files.  In
	// addition, it will append the external test package (if any)
	// to Program.Created.
	ImportPkgs map[string]bool

	// FindPackage is called during Load to create the build.Package
	// for a given import path from a given directory.
	// If FindPackage is nil, (*build.Context).Import is used.
	// A client may use this hook to adapt to a proprietary build
	// system that does not follow the "go build" layout
	// conventions, for example.
	//
	// It must be safe to call concurrently from multiple goroutines.
	FindPackage func(ctxt *build.Context, importPath, fromDir string, mode build.ImportMode) (*build.Package, error)

	// AfterTypeCheck is called immediately after a list of files
	// has been type-checked and appended to info.Files.
	//
	// This optional hook function is the earliest opportunity for
	// the client to observe the output of the type checker,
	// which may be useful to reduce analysis latency when loading
	// a large program.
	//
	// The function is permitted to modify info.Info, for instance
	// to clear data structures that are no longer needed, which can
	// dramatically reduce peak memory consumption.
	//
	// The function may be called twice for the same PackageInfo:
	// once for the files of the package and again for the
	// in-package test files.
	//
	// It must be safe to call concurrently from multiple goroutines.
	AfterTypeCheck func(info *PackageInfo, files []*ast.File)
}

// A PkgSpec specifies a non-importable package to be created by Load.
// Files are processed first, but typically only one of Files and
// Filenames is provided.  The path needn't be globally unique.
//
// For vendoring purposes, the package's directory is the one that
// contains the first file.
type PkgSpec struct {
	Path      string      // package path ("" => use package declaration)
	Files     []*ast.File // ASTs of already-parsed files
	Filenames []string    // names of files to be parsed
}

// A Program is a Go program loaded from source as specified by a Config.
type Program struct {
	Fset *token.FileSet // the file set for this program

	// Created[i] contains the initial package whose ASTs or
	// filenames were supplied by Config.CreatePkgs[i], followed by
	// the external test package, if any, of each package in
	// Config.ImportPkgs ordered by ImportPath.
	//
	// NOTE: these files must not import "C".  Cgo preprocessing is
	// only performed on imported packages, not ad hoc packages.
	//
	// TODO(adonovan): we need to copy and adapt the logic of
	// goFilesPackage (from $GOROOT/src/cmd/go/build.go) and make
	// Config.Import and Config.Create methods return the same kind
	// of entity, essentially a build.Package.
	// Perhaps we can even reuse that type directly.
	Created []*PackageInfo

	// Imported contains the initially imported packages,
	// as specified by Config.ImportPkgs.
	Imported map[string]*PackageInfo

	// AllPackages contains the PackageInfo of every package
	// encountered by Load: all initial packages and all
	// dependencies, including incomplete ones.
	AllPackages map[*types.Package]*PackageInfo

	// importMap is the canonical mapping of package paths to
	// packages.  It contains all Imported initial packages, but not
	// Created ones, and all imported dependencies.
	importMap map[string]*types.Package
}

// PackageInfo holds the ASTs and facts derived by the type-checker
// for a single package.
//
// Not mutated once exposed via the API.
type PackageInfo struct {
	Pkg                   *types.Package
	Importable            bool        // true if 'import "Pkg.Path()"' would resolve to this
	TransitivelyErrorFree bool        // true if Pkg and all its dependencies are free of errors
	Files                 []*ast.File // syntax trees for the package's files
	Errors                []error     // non-nil if the package had errors
	types.Info                        // type-checker deductions.
	dir                   string      // package directory

	checker   *types.Checker // transient type-checker state
	errorFunc func(error)
}

func (info *PackageInfo) String() string { return info.Pkg.Path() }

func (info *PackageInfo) appendError(err error) {
	if info.errorFunc != nil {
		info.errorFunc(err)
	} else {
		fmt.Fprintln(os.Stderr, err)
	}
	info.Errors = append(info.Errors, err)
}

func (conf *Config) fset() *token.FileSet {
	if conf.Fset == nil {
		conf.Fset = token.NewFileSet()
	}
	return conf.Fset
}

// ParseFile is a convenience function (intended for testing) that invokes
// the parser using the Config's FileSet, which is initialized if nil.
//
// src specifies the parser input as a string, []byte, or io.Reader, and
// filename is its apparent name.  If src is nil, the contents of
// filename are read from the file system.
func (conf *Config) ParseFile(filename string, src any) (*ast.File, error) {
	// TODO(adonovan): use conf.build() etc like parseFiles does.
	return parser.ParseFile(conf.fset(), filename, src, conf.ParserMode)
}

// FromArgsUsage is a partial usage message that applications calling
// FromArgs may wish to include in their -help output.
const FromArgsUsage = `
<args> is a list of arguments denoting a set of initial packages.
It may take one of two forms:

1. A list of *.go source files.

   All of the specified files are loaded, parsed and type-checked
   as a single package.  All the files must belong to the same directory.

2. A list of import paths, each denoting a package.

   The package's directory is found relative to the $GOROOT and
   $GOPATH using similar logic to 'go build', and the *.go files in
   that directory are loaded, parsed and type-checked as a single
   package.

   In addition, all *_test.go files in the directory are then loaded
   and parsed.  Those files whose package declaration equals that of
   the non-*_test.go files are included in the primary package.  Test
   files whose package declaration ends with "_test" are type-checked
   as another package, the 'external' test package, so that a single
   import path may denote two packages.  (Whether this behaviour is
   enabled is tool-specific, and may depend on additional flags.)

A '--' argument terminates the list of packages.
`

// FromArgs interprets args as a set of initial packages to load from
// source and updates the configuration.  It returns the list of
// unconsumed arguments.
//
// It is intended for use in command-line interfaces that require a
// set of initial packages to be specified; see FromArgsUsage message
// for details.
//
// Only superficial errors are reported at this stage; errors dependent
// on I/O are detected during Load.
func (conf *Config) FromArgs(args []string, xtest bool) ([]string, error) {
	var rest []string
	for i, arg := range args {
		if arg == "--" {
			rest = args[i+1:]
			args = args[:i]
			break // consume "--" and return the remaining args
		}
	}

	if len(args) > 0 && strings.HasSuffix(args[0], ".go") {
		// Assume args is a list of a *.go files
		// denoting a single ad hoc package.
		for _, arg := range args {
			if !strings.HasSuffix(arg, ".go") {
				return nil, fmt.Errorf("named files must be .go files: %s", arg)
			}
		}
		conf.CreateFromFilenames("", args...)
	} else {
		// Assume args are directories each denoting a
		// package and (perhaps) an external test, iff xtest.
		for _, arg := range args {
			if xtest {
				conf.ImportWithTests(arg)
			} else {
				conf.Import(arg)
			}
		}
	}

	return rest, nil
}

// CreateFromFilenames is a convenience function that adds
// a conf.CreatePkgs entry to create a package of the specified *.go
// files.
func (conf *Config) CreateFromFilenames(path string, filenames ...string) {
	conf.CreatePkgs = append(conf.CreatePkgs, PkgSpec{Path: path, Filenames: filenames})
}

// CreateFromFiles is a convenience function that adds a conf.CreatePkgs
// entry to create package of the specified path and parsed files.
func (conf *Config) CreateFromFiles(path string, files ...*ast.File) {
	conf.CreatePkgs = append(conf.CreatePkgs, PkgSpec{Path: path, Files: files})
}

// ImportWithTests is a convenience function that adds path to
// ImportPkgs, the set of initial source packages located relative to
// $GOPATH.  The package will be augmented by any *_test.go files in
// its directory that contain a "package x" (not "package x_test")
// declaration.
//
// In addition, if any *_test.go files contain a "package x_test"
// declaration, an additional package comprising just those files will
// be added to CreatePkgs.
func (conf *Config) ImportWithTests(path string) { conf.addImport(path, true) }

// Import is a convenience function that adds path to ImportPkgs, the
// set of initial packages that will be imported from source.
func (conf *Config) Import(path string) { conf.addImport(path, false) }

func (conf *Config) addImport(path string, tests bool) {
	if path == "C" {
		return // ignore; not a real package
	}
	if conf.ImportPkgs == nil {
		conf.ImportPkgs = make(map[string]bool)
	}
	conf.ImportPkgs[path] = conf.ImportPkgs[path] || tests
}

// PathEnclosingInterval returns the PackageInfo and ast.Node that
// contain source interval [start, end), and all the node's ancestors
// up to the AST root.  It searches all ast.Files of all packages in prog.
// exact is defined as for astutil.PathEnclosingInterval.
//
// The zero value is returned if not found.
func (prog *Program) PathEnclosingInterval(start, end token.Pos) (pkg *PackageInfo, path []ast.Node, exact bool) {
	for _, info := range prog.AllPackages {
		for _, f := range info.Files {
			if !tokenFileContainsPos(prog.Fset.File(f.FileStart), start) {
				continue
			}
			if path, exact := astutil.PathEnclosingInterval(f, start, end); path != nil {
				return info, path, exact
			}
		}
	}
	return nil, nil, false
}

// InitialPackages returns a new slice containing the set of initial
// packages (Created + Imported) in unspecified order.
func (prog *Program) InitialPackages() []*PackageInfo {
	infos := make([]*PackageInfo, 0, len(prog.Created)+len(prog.Imported))
	infos = append(infos, prog.Created...)
	for _, info := range prog.Imported {
		infos = append(infos, info)
	}
	return infos
}

// Package returns the ASTs and results of type checking for the
// specified package.
func (prog *Program) Package(path string) *PackageInfo {
	if info, ok := prog.AllPackages[prog.importMap[path]]; ok {
		return info
	}
	for _, info := range prog.Created {
		if path == info.Pkg.Path() {
			return info
		}
	}
	return nil
}

// ---------- Implementation ----------

// importer holds the working state of the algorithm.
type importer struct {
	conf  *Config   // the client configuration
	start time.Time // for logging

	progMu sync.Mutex // guards prog
	prog   *Program   // the resulting program

	// findpkg is a memoization of FindPackage.
	findpkgMu sync.Mutex // guards findpkg
	findpkg   map[findpkgKey]*findpkgValue

	importedMu sync.Mutex             // guards imported
	imported   map[string]*importInfo // all imported packages (incl. failures) by import path

	// import dependency graph: graph[x][y] => x imports y
	//
	// Since non-importable packages cannot be cyclic, we ignore
	// their imports, thus we only need the subgraph over importable
	// packages.  Nodes are identified by their import paths.
	graphMu sync.Mutex
	graph   map[string]map[string]bool
}

type findpkgKey struct {
	importPath string
	fromDir    string
	mode       build.ImportMode
}

type findpkgValue struct {
	ready chan struct{} // closed to broadcast readiness
	bp    *build.Package
	err   error
}

// importInfo tracks the success or failure of a single import.
//
// Upon completion, exactly one of info and err is non-nil:
// info on successful creation of a package, err otherwise.
// A successful package may still contain type errors.
type importInfo struct {
	path     string        // import path
	info     *PackageInfo  // results of typechecking (including errors)
	complete chan struct{} // closed to broadcast that info is set.
}

// awaitCompletion blocks until ii is complete,
// i.e. the info field is safe to inspect.
func (ii *importInfo) awaitCompletion() {
	<-ii.complete // wait for close
}

// Complete marks ii as complete.
// Its info and err fields will not be subsequently updated.
func (ii *importInfo) Complete(info *PackageInfo) {
	if info == nil {
		panic("info == nil")
	}
	ii.info = info
	close(ii.complete)
}

type importError struct {
	path string // import path
	err  error  // reason for failure to create a package
}

// Load creates the initial packages specified by conf.{Create,Import}Pkgs,
// loading their dependencies packages as needed.
//
// On success, Load returns a Program containing a PackageInfo for
// each package.  On failure, it returns an error.
//
// If AllowErrors is true, Load will return a Program even if some
// packages contained I/O, parser or type errors, or if dependencies
// were missing.  (Such errors are accessible via PackageInfo.Errors.  If
// false, Load will fail if any package had an error.
//
// It is an error if no packages were loaded.
func (conf *Config) Load() (*Program, error) {
	// Create a simple default error handler for parse/type errors.
	if conf.TypeChecker.Error == nil {
		conf.TypeChecker.Error = func(e error) { fmt.Fprintln(os.Stderr, e) }
	}

	// Set default working directory for relative package references.
	if conf.Cwd == "" {
		var err error
		conf.Cwd, err = os.Getwd()
		if err != nil {
			return nil, err
		}
	}

	// Install default FindPackage hook using go/build logic.
	if conf.FindPackage == nil {
		conf.FindPackage = (*build.Context).Import
	}

	prog := &Program{
		Fset:        conf.fset(),
		Imported:    make(map[string]*PackageInfo),
		importMap:   make(map[string]*types.Package),
		AllPackages: make(map[*types.Package]*PackageInfo),
	}

	imp := importer{
		conf:     conf,
		prog:     prog,
		findpkg:  make(map[findpkgKey]*findpkgValue),
		imported: make(map[string]*importInfo),
		start:    time.Now(),
		graph:    make(map[string]map[string]bool),
	}

	// -- loading proper (concurrent phase) --------------------------------

	var errpkgs []string // packages that contained errors

	// Load the initially imported packages and their dependencies,
	// in parallel.
	// No vendor check on packages imported from the command line.
	infos, importErrors := imp.importAll("", conf.Cwd, conf.ImportPkgs, ignoreVendor)
	for _, ie := range importErrors {
		conf.TypeChecker.Error(ie.err) // failed to create package
		errpkgs = append(errpkgs, ie.path)
	}
	for _, info := range infos {
		prog.Imported[info.Pkg.Path()] = info
	}

	// Augment the designated initial packages by their tests.
	// Dependencies are loaded in parallel.
	var xtestPkgs []*build.Package
	for importPath, augment := range conf.ImportPkgs {
		if !augment {
			continue
		}

		// No vendor check on packages imported from command line.
		bp, err := imp.findPackage(importPath, conf.Cwd, ignoreVendor)
		if err != nil {
			// Package not found, or can't even parse package declaration.
			// Already reported by previous loop; ignore it.
			continue
		}

		// Needs external test package?
		if len(bp.XTestGoFiles) > 0 {
			xtestPkgs = append(xtestPkgs, bp)
		}

		// Consult the cache using the canonical package path.
		path := bp.ImportPath
		imp.importedMu.Lock() // (unnecessary, we're sequential here)
		ii, ok := imp.imported[path]
		// Paranoid checks added due to issue #11012.
		if !ok {
			// Unreachable.
			// The previous loop called importAll and thus
			// startLoad for each path in ImportPkgs, which
			// populates imp.imported[path] with a non-zero value.
			panic(fmt.Sprintf("imported[%q] not found", path))
		}
		if ii == nil {
			// Unreachable.
			// The ii values in this loop are the same as in
			// the previous loop, which enforced the invariant
			// that at least one of ii.err and ii.info is non-nil.
			panic(fmt.Sprintf("imported[%q] == nil", path))
		}
		if ii.info == nil {
			// Unreachable.
			// awaitCompletion has the postcondition
			// ii.info != nil.
			panic(fmt.Sprintf("imported[%q].info = nil", path))
		}
		info := ii.info
		imp.importedMu.Unlock()

		// Parse the in-package test files.
		files, errs := imp.conf.parsePackageFiles(bp, 't')
		for _, err := range errs {
			info.appendError(err)
		}

		// The test files augmenting package P cannot be imported,
		// but may import packages that import P,
		// so we must disable the cycle check.
		imp.addFiles(info, files, false)
	}

	createPkg := func(path, dir string, files []*ast.File, errs []error) {
		info := imp.newPackageInfo(path, dir)
		for _, err := range errs {
			info.appendError(err)
		}

		// Ad hoc packages are non-importable,
		// so no cycle check is needed.
		// addFiles loads dependencies in parallel.
		imp.addFiles(info, files, false)
		prog.Created = append(prog.Created, info)
	}

	// Create packages specified by conf.CreatePkgs.
	for _, cp := range conf.CreatePkgs {
		files, errs := parseFiles(conf.fset(), conf.build(), nil, conf.Cwd, cp.Filenames, conf.ParserMode)
		files = append(files, cp.Files...)

		path := cp.Path
		if path == "" {
			if len(files) > 0 {
				path = files[0].Name.Name
			} else {
				path = "(unnamed)"
			}
		}

		dir := conf.Cwd
		if len(files) > 0 && files[0].Pos().IsValid() {
			dir = filepath.Dir(conf.fset().File(files[0].Pos()).Name())
		}
		createPkg(path, dir, files, errs)
	}

	// Create external test packages.
	sort.Sort(byImportPath(xtestPkgs))
	for _, bp := range xtestPkgs {
		files, errs := imp.conf.parsePackageFiles(bp, 'x')
		createPkg(bp.ImportPath+"_test", bp.Dir, files, errs)
	}

	// -- finishing up (sequential) ----------------------------------------

	if len(prog.Imported)+len(prog.Created) == 0 {
		return nil, errors.New("no initial packages were loaded")
	}

	// Create infos for indirectly imported packages.
	// e.g. incomplete packages without syntax, loaded from export data.
	for _, obj := range prog.importMap {
		info := prog.AllPackages[obj]
		if info == nil {
			prog.AllPackages[obj] = &PackageInfo{Pkg: obj, Importable: true}
		} else {
			// finished
			info.checker = nil
			info.errorFunc = nil
		}
	}

	if !conf.AllowErrors {
		// Report errors in indirectly imported packages.
		for _, info := range prog.AllPackages {
			if len(info.Errors) > 0 {
				errpkgs = append(errpkgs, info.Pkg.Path())
			}
		}
		if errpkgs != nil {
			var more string
			if len(errpkgs) > 3 {
				more = fmt.Sprintf(" and %d more", len(errpkgs)-3)
				errpkgs = errpkgs[:3]
			}
			return nil, fmt.Errorf("couldn't load packages due to errors: %s%s",
				strings.Join(errpkgs, ", "), more)
		}
	}

	markErrorFreePackages(prog.AllPackages)

	return prog, nil
}

type byImportPath []*build.Package

func (b byImportPath) Len() int           { return len(b) }
func (b byImportPath) Less(i, j int) bool { return b[i].ImportPath < b[j].ImportPath }
func (b byImportPath) Swap(i, j int)      { b[i], b[j] = b[j], b[i] }

// markErrorFreePackages sets the TransitivelyErrorFree flag on all
// applicable packages.
func markErrorFreePackages(allPackages map[*types.Package]*PackageInfo) {
	// Build the transpose of the import graph.
	importedBy := make(map[*types.Package]map[*types.Package]bool)
	for P := range allPackages {
		for _, Q := range P.Imports() {
			clients, ok := importedBy[Q]
			if !ok {
				clients = make(map[*types.Package]bool)
				importedBy[Q] = clients
			}
			clients[P] = true
		}
	}

	// Find all packages reachable from some error package.
	reachable := make(map[*types.Package]bool)
	var visit func(*types.Package)
	visit = func(p *types.Package) {
		if !reachable[p] {
			reachable[p] = true
			for q := range importedBy[p] {
				visit(q)
			}
		}
	}
	for _, info := range allPackages {
		if len(info.Errors) > 0 {
			visit(info.Pkg)
		}
	}

	// Mark the others as "transitively error-free".
	for _, info := range allPackages {
		if !reachable[info.Pkg] {
			info.TransitivelyErrorFree = true
		}
	}
}

// build returns the effective build context.
func (conf *Config) build() *build.Context {
	if conf.Build != nil {
		return conf.Build
	}
	return &build.Default
}

// parsePackageFiles enumerates the files belonging to package path,
// then loads, parses and returns them, plus a list of I/O or parse
// errors that were encountered.
//
// 'which' indicates which files to include:
//
//	'g': include non-test *.go source files (GoFiles + processed CgoFiles)
//	't': include in-package *_test.go source files (TestGoFiles)
//	'x': include external *_test.go source files. (XTestGoFiles)
func (conf *Config) parsePackageFiles(bp *build.Package, which rune) ([]*ast.File, []error) {
	if bp.ImportPath == "unsafe" {
		return nil, nil
	}
	var filenames []string
	switch which {
	case 'g':
		filenames = bp.GoFiles
	case 't':
		filenames = bp.TestGoFiles
	case 'x':
		filenames = bp.XTestGoFiles
	default:
		panic(which)
	}

	files, errs := parseFiles(conf.fset(), conf.build(), conf.DisplayPath, bp.Dir, filenames, conf.ParserMode)

	// Preprocess CgoFiles and parse the outputs (sequentially).
	if which == 'g' && bp.CgoFiles != nil {
		cgofiles, err := cgo.ProcessFiles(bp, conf.fset(), conf.DisplayPath, conf.ParserMode)
		if err != nil {
			errs = append(errs, err)
		} else {
			files = append(files, cgofiles...)
		}
	}

	return files, errs
}

// doImport imports the package denoted by path.
// It implements the types.Importer signature.
//
// It returns an error if a package could not be created
// (e.g. go/build or parse error), but type errors are reported via
// the types.Config.Error callback (the first of which is also saved
// in the package's PackageInfo).
//
// Idempotent.
func (imp *importer) doImport(from *PackageInfo, to string) (*types.Package, error) {
	if to == "C" {
		// This should be unreachable, but ad hoc packages are
		// not currently subject to cgo preprocessing.
		// See https://golang.org/issue/11627.
		return nil, fmt.Errorf(`the loader doesn't cgo-process ad hoc packages like %q; see Go issue 11627`,
			from.Pkg.Path())
	}

	bp, err := imp.findPackage(to, from.dir, 0)
	if err != nil {
		return nil, err
	}

	// The standard unsafe package is handled specially,
	// and has no PackageInfo.
	if bp.ImportPath == "unsafe" {
		return types.Unsafe, nil
	}

	// Look for the package in the cache using its canonical path.
	path := bp.ImportPath
	imp.importedMu.Lock()
	ii := imp.imported[path]
	imp.importedMu.Unlock()
	if ii == nil {
		panic("internal error: unexpected import: " + path)
	}
	if ii.info != nil {
		return ii.info.Pkg, nil
	}

	// Import of incomplete package: this indicates a cycle.
	fromPath := from.Pkg.Path()
	if cycle := imp.findPath(path, fromPath); cycle != nil {
		// Normalize cycle: start from alphabetically largest node.
		pos, start := -1, ""
		for i, s := range cycle {
			if pos < 0 || s > start {
				pos, start = i, s
			}
		}
		cycle = append(cycle, cycle[:pos]...)[pos:] // rotate cycle to start from largest
		cycle = append(cycle, cycle[0])             // add start node to end to show cycliness
		return nil, fmt.Errorf("import cycle: %s", strings.Join(cycle, " -> "))
	}

	panic("internal error: import of incomplete (yet acyclic) package: " + fromPath)
}

// findPackage locates the package denoted by the importPath in the
// specified directory.
func (imp *importer) findPackage(importPath, fromDir string, mode build.ImportMode) (*build.Package, error) {
	// We use a non-blocking duplicate-suppressing cache (gopl.io §9.7)
	// to avoid holding the lock around FindPackage.
	key := findpkgKey{importPath, fromDir, mode}
	imp.findpkgMu.Lock()
	v, ok := imp.findpkg[key]
	if ok {
		// cache hit
		imp.findpkgMu.Unlock()

		<-v.ready // wait for entry to become ready
	} else {
		// Cache miss: this goroutine becomes responsible for
		// populating the map entry and broadcasting its readiness.
		v = &findpkgValue{ready: make(chan struct{})}
		imp.findpkg[key] = v
		imp.findpkgMu.Unlock()

		ioLimit <- true
		v.bp, v.err = imp.conf.FindPackage(imp.conf.build(), importPath, fromDir, mode)
		<-ioLimit

		if _, ok := v.err.(*build.NoGoError); ok {
			v.err = nil // empty directory is not an error
		}

		close(v.ready) // broadcast ready condition
	}
	return v.bp, v.err
}

// importAll loads, parses, and type-checks the specified packages in
// parallel and returns their completed importInfos in unspecified order.
//
// fromPath is the package path of the importing package, if it is
// importable, "" otherwise.  It is used for cycle detection.
//
// fromDir is the directory containing the import declaration that
// caused these imports.
func (imp *importer) importAll(fromPath, fromDir string, imports map[string]bool, mode build.ImportMode) (infos []*PackageInfo, errors []importError) {
	if fromPath != "" {
		// We're loading a set of imports.
		//
		// We must record graph edges from the importing package
		// to its dependencies, and check for cycles.
		imp.graphMu.Lock()
		deps, ok := imp.graph[fromPath]
		if !ok {
			deps = make(map[string]bool)
			imp.graph[fromPath] = deps
		}
		for importPath := range imports {
			deps[importPath] = true
		}
		imp.graphMu.Unlock()
	}

	var pending []*importInfo
	for importPath := range imports {
		if fromPath != "" {
			if cycle := imp.findPath(importPath, fromPath); cycle != nil {
				// Cycle-forming import: we must not check it
				// since it would deadlock.
				if trace {
					fmt.Fprintf(os.Stderr, "import cycle: %q\n", cycle)
				}
				continue
			}
		}
		bp, err := imp.findPackage(importPath, fromDir, mode)
		if err != nil {
			errors = append(errors, importError{
				path: importPath,
				err:  err,
			})
			continue
		}
		pending = append(pending, imp.startLoad(bp))
	}

	for _, ii := range pending {
		ii.awaitCompletion()
		infos = append(infos, ii.info)
	}

	return infos, errors
}

// findPath returns an arbitrary path from 'from' to 'to' in the import
// graph, or nil if there was none.
func (imp *importer) findPath(from, to string) []string {
	imp.graphMu.Lock()
	defer imp.graphMu.Unlock()

	seen := make(map[string]bool)
	var search func(stack []string, importPath string) []string
	search = func(stack []string, importPath string) []string {
		if !seen[importPath] {
			seen[importPath] = true
			stack = append(stack, importPath)
			if importPath == to {
				return stack
			}
			for x := range imp.graph[importPath] {
				if p := search(stack, x); p != nil {
					return p
				}
			}
		}
		return nil
	}
	return search(make([]string, 0, 20), from)
}

// startLoad initiates the loading, parsing and type-checking of the
// specified package and its dependencies, if it has not already begun.
//
// It returns an importInfo, not necessarily in a completed state.  The
// caller must call awaitCompletion() before accessing its info field.
//
// startLoad is concurrency-safe and idempotent.
func (imp *importer) startLoad(bp *build.Package) *importInfo {
	path := bp.ImportPath
	imp.importedMu.Lock()
	ii, ok := imp.imported[path]
	if !ok {
		ii = &importInfo{path: path, complete: make(chan struct{})}
		imp.imported[path] = ii
		go func() {
			info := imp.load(bp)
			ii.Complete(info)
		}()
	}
	imp.importedMu.Unlock()

	return ii
}

// load implements package loading by parsing Go source files
// located by go/build.
func (imp *importer) load(bp *build.Package) *PackageInfo {
	info := imp.newPackageInfo(bp.ImportPath, bp.Dir)
	info.Importable = true
	files, errs := imp.conf.parsePackageFiles(bp, 'g')
	for _, err := range errs {
		info.appendError(err)
	}

	imp.addFiles(info, files, true)

	imp.progMu.Lock()
	imp.prog.importMap[bp.ImportPath] = info.Pkg
	imp.progMu.Unlock()

	return info
}

// addFiles adds and type-checks the specified files to info, loading
// their dependencies if needed.  The order of files determines the
// package initialization order.  It may be called multiple times on the
// same package.  Errors are appended to the info.Errors field.
//
// cycleCheck determines whether the imports within files create
// dependency edges that should be checked for potential cycles.
func (imp *importer) addFiles(info *PackageInfo, files []*ast.File, cycleCheck bool) {
	// Ensure the dependencies are loaded, in parallel.
	var fromPath string
	if cycleCheck {
		fromPath = info.Pkg.Path()
	}
	// TODO(adonovan): opt: make the caller do scanImports.
	// Callers with a build.Package can skip it.
	imp.importAll(fromPath, info.dir, scanImports(files), 0)

	if trace {
		fmt.Fprintf(os.Stderr, "%s: start %q (%d)\n",
			time.Since(imp.start), info.Pkg.Path(), len(files))
	}

	// Don't call checker.Files on Unsafe, even with zero files,
	// because it would mutate the package, which is a global.
	if info.Pkg == types.Unsafe {
		if len(files) > 0 {
			panic(`"unsafe" package contains unexpected files`)
		}
	} else {
		// Ignore the returned (first) error since we
		// already collect them all in the PackageInfo.
		info.checker.Files(files)
		info.Files = append(info.Files, files...)
	}

	if imp.conf.AfterTypeCheck != nil {
		imp.conf.AfterTypeCheck(info, files)
	}

	if trace {
		fmt.Fprintf(os.Stderr, "%s: stop %q\n",
			time.Since(imp.start), info.Pkg.Path())
	}
}

func (imp *importer) newPackageInfo(path, dir string) *PackageInfo {
	var pkg *types.Package
	if path == "unsafe" {
		pkg = types.Unsafe
	} else {
		pkg = types.NewPackage(path, "")
	}
	info := &PackageInfo{
		Pkg: pkg,
		Info: types.Info{
			Types:        make(map[ast.Expr]types.TypeAndValue),
			Defs:         make(map[*ast.Ident]types.Object),
			Uses:         make(map[*ast.Ident]types.Object),
			Implicits:    make(map[ast.Node]types.Object),
			Instances:    make(map[*ast.Ident]types.Instance),
			Scopes:       make(map[ast.Node]*types.Scope),
			Selections:   make(map[*ast.SelectorExpr]*types.Selection),
			FileVersions: make(map[*ast.File]string),
		},
		errorFunc: imp.conf.TypeChecker.Error,
		dir:       dir,
	}

	// Copy the types.Config so we can vary it across PackageInfos.
	tc := imp.conf.TypeChecker
	tc.IgnoreFuncBodies = false
	if f := imp.conf.TypeCheckFuncBodies; f != nil {
		tc.IgnoreFuncBodies = !f(path)
	}
	tc.Importer = closure{imp, info}
	tc.Error = info.appendError // appendError wraps the user's Error function

	info.checker = types.NewChecker(&tc, imp.conf.fset(), pkg, &info.Info)
	imp.progMu.Lock()
	imp.prog.AllPackages[pkg] = info
	imp.progMu.Unlock()
	return info
}

type closure struct {
	imp  *importer
	info *PackageInfo
}

func (c closure) Import(to string) (*types.Package, error) { return c.imp.doImport(c.info, to) }


================================================
FILE: go/loader/loader_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package loader_test

import (
	"fmt"
	"go/build"
	"go/constant"
	"go/types"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strings"
	"sync"
	"testing"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	testenv.ExitIfSmallMachine()
	os.Exit(m.Run())
}

// TestFromArgs checks that conf.FromArgs populates conf correctly.
// It does no I/O.
func TestFromArgs(t *testing.T) {
	type result struct {
		Err        string
		Rest       []string
		ImportPkgs map[string]bool
		CreatePkgs []loader.PkgSpec
	}
	for _, test := range []struct {
		args  []string
		tests bool
		want  result
	}{
		// Mix of existing and non-existent packages.
		{
			args: []string{"nosuchpkg", "errors"},
			want: result{
				ImportPkgs: map[string]bool{"errors": false, "nosuchpkg": false},
			},
		},
		// Same, with -test flag.
		{
			args:  []string{"nosuchpkg", "errors"},
			tests: true,
			want: result{
				ImportPkgs: map[string]bool{"errors": true, "nosuchpkg": true},
			},
		},
		// Surplus arguments.
		{
			args: []string{"fmt", "errors", "--", "surplus"},
			want: result{
				Rest:       []string{"surplus"},
				ImportPkgs: map[string]bool{"errors": false, "fmt": false},
			},
		},
		// Ad hoc package specified as *.go files.
		{
			args: []string{"foo.go", "bar.go"},
			want: result{CreatePkgs: []loader.PkgSpec{{
				Filenames: []string{"foo.go", "bar.go"},
			}}},
		},
		// Mixture of *.go and import paths.
		{
			args: []string{"foo.go", "fmt"},
			want: result{
				Err: "named files must be .go files: fmt",
			},
		},
	} {
		var conf loader.Config
		rest, err := conf.FromArgs(test.args, test.tests)
		got := result{
			Rest:       rest,
			ImportPkgs: conf.ImportPkgs,
			CreatePkgs: conf.CreatePkgs,
		}
		if err != nil {
			got.Err = err.Error()
		}
		if !reflect.DeepEqual(got, test.want) {
			t.Errorf("FromArgs(%q) = %+v, want %+v", test.args, got, test.want)
		}
	}
}

func TestLoad_NoInitialPackages(t *testing.T) {
	var conf loader.Config

	const wantErr = "no initial packages were loaded"

	prog, err := conf.Load()
	if err == nil {
		t.Errorf("Load succeeded unexpectedly, want %q", wantErr)
	} else if err.Error() != wantErr {
		t.Errorf("Load failed with wrong error %q, want %q", err, wantErr)
	}
	if prog != nil {
		t.Errorf("Load unexpectedly returned a Program")
	}
}

func TestLoad_MissingInitialPackage(t *testing.T) {
	if runtime.GOOS == "wasip1" {
		t.Skip("Skipping due to golang/go#64725: fails with EBADF errors")
	}

	var conf loader.Config
	conf.Import("nosuchpkg")
	conf.Import("errors")

	const wantErr = "couldn't load packages due to errors: nosuchpkg"

	prog, err := conf.Load()
	if err == nil {
		t.Errorf("Load succeeded unexpectedly, want %q", wantErr)
	} else if err.Error() != wantErr {
		t.Errorf("Load failed with wrong error %q, want %q", err, wantErr)
	}
	if prog != nil {
		t.Errorf("Load unexpectedly returned a Program")
	}
}

func TestLoad_MissingInitialPackage_AllowErrors(t *testing.T) {
	if runtime.Compiler == "gccgo" {
		t.Skip("gccgo has no standard library test files")
	}

	var conf loader.Config
	conf.AllowErrors = true
	conf.Import("nosuchpkg")
	conf.ImportWithTests("errors")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed unexpectedly: %v", err)
	}
	if prog == nil {
		t.Fatalf("Load returned a nil Program")
	}
	if got, want := created(prog), "errors_test"; got != want {
		t.Errorf("Created = %s, want %s", got, want)
	}
	if got, want := imported(prog), "errors"; got != want {
		t.Errorf("Imported = %s, want %s", got, want)
	}
}

func TestCreateUnnamedPackage(t *testing.T) {
	var conf loader.Config
	conf.CreateFromFilenames("")
	prog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load failed: %v", err)
	}
	if got, want := fmt.Sprint(prog.InitialPackages()), "[(unnamed)]"; got != want {
		t.Errorf("InitialPackages = %s, want %s", got, want)
	}
}

func TestLoad_MissingFileInCreatedPackage(t *testing.T) {
	var conf loader.Config
	conf.CreateFromFilenames("", "missing.go")

	const wantErr = "couldn't load packages due to errors: (unnamed)"

	prog, err := conf.Load()
	if prog != nil {
		t.Errorf("Load unexpectedly returned a Program")
	}
	if err == nil {
		t.Fatalf("Load succeeded unexpectedly, want %q", wantErr)
	}
	if err.Error() != wantErr {
		t.Fatalf("Load failed with wrong error %q, want %q", err, wantErr)
	}
}

func TestLoad_MissingFileInCreatedPackage_AllowErrors(t *testing.T) {
	conf := loader.Config{AllowErrors: true}
	conf.CreateFromFilenames("", "missing.go")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed: %v", err)
	}
	if got, want := fmt.Sprint(prog.InitialPackages()), "[(unnamed)]"; got != want {
		t.Fatalf("InitialPackages = %s, want %s", got, want)
	}
}

func TestLoad_ParseError(t *testing.T) {
	var conf loader.Config
	conf.CreateFromFilenames("badpkg", "testdata/badpkgdecl.go")

	const wantErr = "couldn't load packages due to errors: badpkg"

	prog, err := conf.Load()
	if prog != nil {
		t.Errorf("Load unexpectedly returned a Program")
	}
	if err == nil {
		t.Fatalf("Load succeeded unexpectedly, want %q", wantErr)
	}
	if err.Error() != wantErr {
		t.Fatalf("Load failed with wrong error %q, want %q", err, wantErr)
	}
}

func TestLoad_ParseError_AllowErrors(t *testing.T) {
	var conf loader.Config
	conf.AllowErrors = true
	conf.CreateFromFilenames("badpkg", "testdata/badpkgdecl.go")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed unexpectedly: %v", err)
	}
	if prog == nil {
		t.Fatalf("Load returned a nil Program")
	}
	if got, want := created(prog), "badpkg"; got != want {
		t.Errorf("Created = %s, want %s", got, want)
	}

	badpkg := prog.Created[0]
	if len(badpkg.Files) != 1 {
		t.Errorf("badpkg has %d files, want 1", len(badpkg.Files))
	}
	wantErr := filepath.Join("testdata", "badpkgdecl.go") + ":1:34: expected 'package', found 'EOF'"
	if !hasError(badpkg.Errors, wantErr) {
		t.Errorf("badpkg.Errors = %v, want %s", badpkg.Errors, wantErr)
	}
}

func TestLoad_FromSource_Success(t *testing.T) {
	var conf loader.Config
	conf.CreateFromFilenames("P", "testdata/a.go", "testdata/b.go")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed unexpectedly: %v", err)
	}
	if prog == nil {
		t.Fatalf("Load returned a nil Program")
	}
	if got, want := created(prog), "P"; got != want {
		t.Errorf("Created = %s, want %s", got, want)
	}
}

func TestLoad_FromImports_Success(t *testing.T) {
	if runtime.Compiler == "gccgo" {
		t.Skip("gccgo has no standard library test files")
	}

	var conf loader.Config
	conf.ImportWithTests("fmt")
	conf.ImportWithTests("errors")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed unexpectedly: %v", err)
	}
	if prog == nil {
		t.Fatalf("Load returned a nil Program")
	}
	if got, want := created(prog), "errors_test fmt_test"; got != want {
		t.Errorf("Created = %q, want %s", got, want)
	}
	if got, want := imported(prog), "errors fmt"; got != want {
		t.Errorf("Imported = %s, want %s", got, want)
	}
	// Check set of transitive packages.
	// There are >30 and the set may grow over time, so only check a few.
	want := map[string]bool{
		"strings": true,
		"time":    true,
		"runtime": true,
		"testing": true,
		"unicode": true,
	}
	for _, path := range all(prog) {
		delete(want, path)
	}
	if len(want) > 0 {
		t.Errorf("AllPackages is missing these keys: %q", keys(want))
	}
}

func TestLoad_MissingIndirectImport(t *testing.T) {
	pkgs := map[string]string{
		"a": `package a; import _ "b"`,
		"b": `package b; import _ "c"`,
	}
	conf := loader.Config{Build: fakeContext(pkgs)}
	conf.Import("a")

	const wantErr = "couldn't load packages due to errors: b"

	prog, err := conf.Load()
	if err == nil {
		t.Errorf("Load succeeded unexpectedly, want %q", wantErr)
	} else if err.Error() != wantErr {
		t.Errorf("Load failed with wrong error %q, want %q", err, wantErr)
	}
	if prog != nil {
		t.Errorf("Load unexpectedly returned a Program")
	}
}

func TestLoad_BadDependency_AllowErrors(t *testing.T) {
	for _, test := range []struct {
		descr    string
		pkgs     map[string]string
		wantPkgs string
	}{

		{
			descr: "missing dependency",
			pkgs: map[string]string{
				"a": `package a; import _ "b"`,
				"b": `package b; import _ "c"`,
			},
			wantPkgs: "a b",
		},
		{
			descr: "bad package decl in dependency",
			pkgs: map[string]string{
				"a": `package a; import _ "b"`,
				"b": `package b; import _ "c"`,
				"c": `package`,
			},
			wantPkgs: "a b",
		},
		{
			descr: "parse error in dependency",
			pkgs: map[string]string{
				"a": `package a; import _ "b"`,
				"b": `package b; import _ "c"`,
				"c": `package c; var x = `,
			},
			wantPkgs: "a b c",
		},
	} {
		conf := loader.Config{
			AllowErrors: true,
			Build:       fakeContext(test.pkgs),
		}
		conf.Import("a")

		prog, err := conf.Load()
		if err != nil {
			t.Errorf("%s: Load failed unexpectedly: %v", test.descr, err)
		}
		if prog == nil {
			t.Fatalf("%s: Load returned a nil Program", test.descr)
		}

		if got, want := imported(prog), "a"; got != want {
			t.Errorf("%s: Imported = %s, want %s", test.descr, got, want)
		}
		if got := all(prog); strings.Join(got, " ") != test.wantPkgs {
			t.Errorf("%s: AllPackages = %s, want %s", test.descr, got, test.wantPkgs)
		}
	}
}

func TestCwd(t *testing.T) {
	ctxt := fakeContext(map[string]string{"one/two/three": `package three`})
	for _, test := range []struct {
		cwd, arg, want string
	}{
		{cwd: "/go/src/one", arg: "./two/three", want: "one/two/three"},
		{cwd: "/go/src/one", arg: "../one/two/three", want: "one/two/three"},
		{cwd: "/go/src/one", arg: "one/two/three", want: "one/two/three"},
		{cwd: "/go/src/one/two/three", arg: ".", want: "one/two/three"},
		{cwd: "/go/src/one", arg: "two/three", want: ""},
	} {
		conf := loader.Config{
			Cwd:   test.cwd,
			Build: ctxt,
		}
		conf.Import(test.arg)

		var got string
		prog, err := conf.Load()
		if prog != nil {
			got = imported(prog)
		}
		if got != test.want {
			t.Errorf("Load(%s) from %s: Imported = %s, want %s",
				test.arg, test.cwd, got, test.want)
			if err != nil {
				t.Errorf("Load failed: %v", err)
			}
		}
	}
}

func TestLoad_vendor(t *testing.T) {
	pkgs := map[string]string{
		"a":          `package a; import _ "x"`,
		"a/vendor":   ``, // mkdir a/vendor
		"a/vendor/x": `package xa`,
		"b":          `package b; import _ "x"`,
		"b/vendor":   ``, // mkdir b/vendor
		"b/vendor/x": `package xb`,
		"c":          `package c; import _ "x"`,
		"x":          `package xc`,
	}
	conf := loader.Config{Build: fakeContext(pkgs)}
	conf.Import("a")
	conf.Import("b")
	conf.Import("c")

	prog, err := conf.Load()
	if err != nil {
		t.Fatal(err)
	}

	// Check that a, b, and c see different versions of x.
	for _, r := range "abc" {
		name := string(r)
		got := prog.Package(name).Pkg.Imports()[0]
		want := "x" + name
		if got.Name() != want {
			t.Errorf("package %s import %q = %s, want %s",
				name, "x", got.Name(), want)
		}
	}
}

func TestVendorCwd(t *testing.T) {
	// Test the interaction of cwd and vendor directories.
	ctxt := fakeContext(map[string]string{
		"net":          ``, // mkdir net
		"net/http":     `package http; import _ "hpack"`,
		"vendor":       ``, // mkdir vendor
		"vendor/hpack": `package vendorhpack`,
		"hpack":        `package hpack`,
	})
	for i, test := range []struct {
		cwd, arg, want string
	}{
		{cwd: "/go/src/net", arg: "http"}, // not found
		{cwd: "/go/src/net", arg: "./http", want: "net/http vendor/hpack"},
		{cwd: "/go/src/net", arg: "hpack", want: "vendor/hpack"},
		{cwd: "/go/src/vendor", arg: "hpack", want: "vendor/hpack"},
		{cwd: "/go/src/vendor", arg: "./hpack", want: "vendor/hpack"},
	} {
		conf := loader.Config{
			Cwd:   test.cwd,
			Build: ctxt,
		}
		conf.Import(test.arg)

		var got string
		prog, err := conf.Load()
		if prog != nil {
			got = strings.Join(all(prog), " ")
		}
		if got != test.want {
			t.Errorf("#%d: Load(%s) from %s: got %s, want %s",
				i, test.arg, test.cwd, got, test.want)
			if err != nil {
				t.Errorf("Load failed: %v", err)
			}
		}
	}
}

func TestVendorCwdIssue16580(t *testing.T) {
	// Regression test for Go issue 16580.
	// Import decls in "created" packages were vendor-resolved
	// w.r.t. cwd, not the parent directory of the package's files.
	ctxt := fakeContext(map[string]string{
		"a":          ``, // mkdir a
		"a/vendor":   ``, // mkdir a/vendor
		"a/vendor/b": `package b; const X = true`,
		"b":          `package b; const X = false`,
	})
	for _, test := range []struct {
		filename, cwd string
		want          bool // expected value of b.X; depends on filename, not on cwd
	}{
		{filename: "c.go", cwd: "/go/src", want: false},
		{filename: "c.go", cwd: "/go/src/a", want: false},
		{filename: "c.go", cwd: "/go/src/a/b", want: false},
		{filename: "c.go", cwd: "/go/src/a/vendor/b", want: false},

		{filename: "/go/src/a/c.go", cwd: "/go/src", want: true},
		{filename: "/go/src/a/c.go", cwd: "/go/src/a", want: true},
		{filename: "/go/src/a/c.go", cwd: "/go/src/a/b", want: true},
		{filename: "/go/src/a/c.go", cwd: "/go/src/a/vendor/b", want: true},

		{filename: "/go/src/c/c.go", cwd: "/go/src", want: false},
		{filename: "/go/src/c/c.go", cwd: "/go/src/a", want: false},
		{filename: "/go/src/c/c.go", cwd: "/go/src/a/b", want: false},
		{filename: "/go/src/c/c.go", cwd: "/go/src/a/vendor/b", want: false},
	} {
		conf := loader.Config{
			Cwd:   test.cwd,
			Build: ctxt,
		}
		f, err := conf.ParseFile(test.filename, `package dummy; import "b"; const X = b.X`)
		if err != nil {
			t.Fatal(f)
		}
		conf.CreateFromFiles("dummy", f)

		prog, err := conf.Load()
		if err != nil {
			t.Errorf("%+v: Load failed: %v", test, err)
			continue
		}

		x := constant.BoolVal(prog.Created[0].Pkg.Scope().Lookup("X").(*types.Const).Val())
		if x != test.want {
			t.Errorf("%+v: b.X = %t", test, x)
		}
	}

	// TODO(adonovan): also test imports within XTestGoFiles.
}

// TODO(adonovan): more Load tests:
//
// failures:
// - to parse package decl of *_test.go files
// - to parse package decl of external *_test.go files
// - to parse whole of *_test.go files
// - to parse whole of external *_test.go files
// - to open a *.go file during import scanning
// - to import from binary

// features:
// - InitialPackages
// - PackageCreated hook
// - TypeCheckFuncBodies hook

func TestTransitivelyErrorFreeFlag(t *testing.T) {
	// Create a minimal custom build.Context
	// that fakes the following packages:
	//
	// a --> b --> c!   c has an error
	//   \              d and e are transitively error-free.
	//    e --> d
	//
	// Each package [a-e] consists of one file, x.go.
	pkgs := map[string]string{
		"a": `package a; import (_ "b"; _ "e")`,
		"b": `package b; import _ "c"`,
		"c": `package c; func f() { _ = int(false) }`, // type error within function body
		"d": `package d;`,
		"e": `package e; import _ "d"`,
	}
	conf := loader.Config{
		AllowErrors: true,
		Build:       fakeContext(pkgs),
	}
	conf.Import("a")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed: %s", err)
	}
	if prog == nil {
		t.Fatalf("Load returned nil *Program")
	}

	for pkg, info := range prog.AllPackages {
		var wantErr, wantTEF bool
		switch pkg.Path() {
		case "a", "b":
		case "c":
			wantErr = true
		case "d", "e":
			wantTEF = true
		default:
			t.Errorf("unexpected package: %q", pkg.Path())
			continue
		}

		if (info.Errors != nil) != wantErr {
			if wantErr {
				t.Errorf("Package %q.Error = nil, want error", pkg.Path())
			} else {
				t.Errorf("Package %q has unexpected Errors: %v",
					pkg.Path(), info.Errors)
			}
		}

		if info.TransitivelyErrorFree != wantTEF {
			t.Errorf("Package %q.TransitivelyErrorFree=%t, want %t",
				pkg.Path(), info.TransitivelyErrorFree, wantTEF)
		}
	}
}

// Test that syntax (scan/parse), type, and loader errors are recorded
// (in PackageInfo.Errors) and reported (via Config.TypeChecker.Error).
func TestErrorReporting(t *testing.T) {
	pkgs := map[string]string{
		"a": `package a; import (_ "b"; _ "c"); var x int = false`,
		"b": `package b; 'syntax error!`,
	}
	conf := loader.Config{
		AllowErrors: true,
		Build:       fakeContext(pkgs),
	}
	var mu sync.Mutex
	var allErrors []error
	conf.TypeChecker.Error = func(err error) {
		mu.Lock()
		allErrors = append(allErrors, err)
		mu.Unlock()
	}
	conf.Import("a")

	prog, err := conf.Load()
	if err != nil {
		t.Errorf("Load failed: %s", err)
	}
	if prog == nil {
		t.Fatalf("Load returned nil *Program")
	}

	// TODO(adonovan): test keys of ImportMap.

	// Check errors recorded in each PackageInfo.
	for pkg, info := range prog.AllPackages {
		switch pkg.Path() {
		case "a":
			// The match below is unfortunately vague, because in go1.16 the error
			// message in go/types changed from "cannot convert ..." to "cannot use
			// ... as ... in assignment".
			if !hasError(info.Errors, "cannot") {
				t.Errorf("a.Errors = %v, want bool assignment (type) error", info.Errors)
			}
			if !hasError(info.Errors, "could not import c") {
				t.Errorf("a.Errors = %v, want import (loader) error", info.Errors)
			}
		case "b":
			if !hasError(info.Errors, "rune literal not terminated") {
				t.Errorf("b.Errors = %v, want unterminated literal (syntax) error", info.Errors)
			}
		}
	}

	// Check errors reported via error handler.
	if !hasError(allErrors, "cannot") ||
		!hasError(allErrors, "rune literal not terminated") ||
		!hasError(allErrors, "could not import c") {
		t.Errorf("allErrors = %v, want syntax, type and loader errors", allErrors)
	}
}

func TestCycles(t *testing.T) {
	for _, test := range []struct {
		descr   string
		ctxt    *build.Context
		wantErr string
	}{
		{
			"self-cycle",
			fakeContext(map[string]string{
				"main":      `package main; import _ "selfcycle"`,
				"selfcycle": `package selfcycle; import _ "selfcycle"`,
			}),
			`import cycle: selfcycle -> selfcycle`,
		},
		{
			"three-package cycle",
			fakeContext(map[string]string{
				"main": `package main; import _ "a"`,
				"a":    `package a; import _ "b"`,
				"b":    `package b; import _ "c"`,
				"c":    `package c; import _ "a"`,
			}),
			`import cycle: c -> a -> b -> c`,
		},
		{
			"self-cycle in dependency of test file",
			buildutil.FakeContext(map[string]map[string]string{
				"main": {
					"main.go":      `package main`,
					"main_test.go": `package main; import _ "a"`,
				},
				"a": {
					"a.go": `package a; import _ "a"`,
				},
			}),
			`import cycle: a -> a`,
		},
		// TODO(adonovan): fix: these fail
		// {
		// 	"two-package cycle in dependency of test file",
		// 	buildutil.FakeContext(map[string]map[string]string{
		// 		"main": {
		// 			"main.go":      `package main`,
		// 			"main_test.go": `package main; import _ "a"`,
		// 		},
		// 		"a": {
		// 			"a.go": `package a; import _ "main"`,
		// 		},
		// 	}),
		// 	`import cycle: main -> a -> main`,
		// },
		// {
		// 	"self-cycle in augmented package",
		// 	buildutil.FakeContext(map[string]map[string]string{
		// 		"main": {
		// 			"main.go":      `package main`,
		// 			"main_test.go": `package main; import _ "main"`,
		// 		},
		// 	}),
		// 	`import cycle: main -> main`,
		// },
	} {
		conf := loader.Config{
			AllowErrors: true,
			Build:       test.ctxt,
		}
		var mu sync.Mutex
		var allErrors []error
		conf.TypeChecker.Error = func(err error) {
			mu.Lock()
			allErrors = append(allErrors, err)
			mu.Unlock()
		}
		conf.ImportWithTests("main")

		prog, err := conf.Load()
		if err != nil {
			t.Errorf("%s: Load failed: %s", test.descr, err)
		}
		if prog == nil {
			t.Fatalf("%s: Load returned nil *Program", test.descr)
		}

		if !hasError(allErrors, test.wantErr) {
			t.Errorf("%s: Load() errors = %q, want %q",
				test.descr, allErrors, test.wantErr)
		}
	}

	// TODO(adonovan):
	// - Test that in a legal test cycle, none of the symbols
	//   defined by augmentation are visible via import.
}

// ---- utilities ----

// Simplifying wrapper around buildutil.FakeContext for single-file packages.
func fakeContext(pkgs map[string]string) *build.Context {
	pkgs2 := make(map[string]map[string]string)
	for path, content := range pkgs {
		pkgs2[path] = map[string]string{"x.go": content}
	}
	return buildutil.FakeContext(pkgs2)
}

func hasError(errors []error, substr string) bool {
	for _, err := range errors {
		if strings.Contains(err.Error(), substr) {
			return true
		}
	}
	return false
}

func keys(m map[string]bool) (keys []string) {
	for key := range m {
		keys = append(keys, key)
	}
	sort.Strings(keys)
	return
}

// Returns all loaded packages.
func all(prog *loader.Program) []string {
	var pkgs []string
	for _, info := range prog.AllPackages {
		pkgs = append(pkgs, info.Pkg.Path())
	}
	sort.Strings(pkgs)
	return pkgs
}

// Returns initially imported packages, as a string.
func imported(prog *loader.Program) string {
	var pkgs []string
	for _, info := range prog.Imported {
		pkgs = append(pkgs, info.Pkg.Path())
	}
	sort.Strings(pkgs)
	return strings.Join(pkgs, " ")
}

// Returns initially created packages, as a string.
func created(prog *loader.Program) string {
	var pkgs []string
	for _, info := range prog.Created {
		pkgs = append(pkgs, info.Pkg.Path())
	}
	return strings.Join(pkgs, " ")
}

// Load package "io" twice in parallel.
// When run with -race, this is a regression test for Go issue 20718, in
// which the global "unsafe" package was modified concurrently.
func TestLoad1(t *testing.T) { loadIO(t) }
func TestLoad2(t *testing.T) { loadIO(t) }

func loadIO(t *testing.T) {
	t.Parallel()
	conf := &loader.Config{ImportPkgs: map[string]bool{"io": false}}
	if _, err := conf.Load(); err != nil {
		t.Fatal(err)
	}
}

func TestCgoCwdIssue46877(t *testing.T) {
	testenv.NeedsTool(t, "go")
	testenv.NeedsTool(t, "cgo")
	var conf loader.Config
	conf.Import("golang.org/x/tools/go/loader/testdata/issue46877")
	if _, err := conf.Load(); err != nil {
		t.Errorf("Load failed: %v", err)
	}
}


================================================
FILE: go/loader/stdlib_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package loader_test

// This file enumerates all packages beneath $GOROOT, loads them, plus
// their external tests if any, runs the type checker on them, and
// prints some summary information.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/internal/testenv"
)

func TestStdlib(t *testing.T) {
	if runtime.GOOS == "android" {
		t.Skipf("incomplete std lib on %s", runtime.GOOS)
	}
	if testing.Short() {
		t.Skip("skipping in short mode; uses tons of memory (https://golang.org/issue/14113)")
	}
	testenv.NeedsTool(t, "go")

	runtime.GC()
	t0 := time.Now()
	var memstats runtime.MemStats
	runtime.ReadMemStats(&memstats)
	alloc := memstats.Alloc

	// Load, parse and type-check the program.
	ctxt := build.Default // copy
	ctxt.GOPATH = ""      // disable GOPATH
	conf := loader.Config{Build: &ctxt}
	for _, path := range buildutil.AllPackages(conf.Build) {
		conf.ImportWithTests(path)
	}

	prog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load failed: %v", err)
	}

	t1 := time.Now()
	runtime.GC()
	runtime.ReadMemStats(&memstats)

	numPkgs := len(prog.AllPackages)
	if want := 205; numPkgs < want {
		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, want)
	}

	// Dump package members.
	if false {
		for pkg := range prog.AllPackages {
			fmt.Printf("Package %s:\n", pkg.Path())
			scope := pkg.Scope()
			qualifier := types.RelativeTo(pkg)
			for _, name := range scope.Names() {
				if ast.IsExported(name) {
					fmt.Printf("\t%s\n", types.ObjectString(scope.Lookup(name), qualifier))
				}
			}
			fmt.Println()
		}
	}

	// Check that Test functions for regexp and compress/bzip2 are
	// simultaneously present. The apparent cycle formed when augmenting
	// these packages by their tests (together with io/ioutil's test, which is now
	// an xtest) was the original motivation or reporting golang.org/issue/7114.
	//
	// compress/bzip2.TestBitReader in bzip2_test.go    imports io/ioutil
	// io/ioutil.TestTempFile       in tempfile_test.go imports regexp (no longer exists)
	// regexp.TestRE2Search         in exec_test.go     imports compress/bzip2
	for _, test := range []struct{ pkg, fn string }{
		{"regexp", "TestRE2Search"},
		{"compress/bzip2", "TestBitReader"},
	} {
		info := prog.Imported[test.pkg]
		if info == nil {
			t.Errorf("failed to load package %q", test.pkg)
			continue
		}
		obj, _ := info.Pkg.Scope().Lookup(test.fn).(*types.Func)
		if obj == nil {
			t.Errorf("package %q has no func %q", test.pkg, test.fn)
			continue
		}
	}

	// Dump some statistics.

	// determine line count
	var lineCount int
	prog.Fset.Iterate(func(f *token.File) bool {
		lineCount += f.LineCount()
		return true
	})

	t.Log("GOMAXPROCS:           ", runtime.GOMAXPROCS(0))
	t.Log("#Source lines:        ", lineCount)
	t.Log("Load/parse/typecheck: ", t1.Sub(t0))
	t.Log("#MB:                  ", int64(memstats.Alloc-alloc)/1000000)
}

func TestCgoOption(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in short mode; uses tons of memory (https://golang.org/issue/14113)")
	}
	switch runtime.GOOS {
	// On these systems, the net and os/user packages don't use cgo
	// or the std library is incomplete (Android).
	case "android", "plan9", "solaris", "windows":
		t.Skipf("no cgo or incomplete std lib on %s", runtime.GOOS)
	case "darwin":
		t.Skipf("golang/go#58493: file locations in this test are stale on darwin")
	}
	testenv.NeedsTool(t, "go")
	// In nocgo builds (e.g. linux-amd64-nocgo),
	// there is no "runtime/cgo" package,
	// so cgo-generated Go files will have a failing import.
	testenv.NeedsTool(t, "cgo")

	// Test that we can load cgo-using packages with
	// CGO_ENABLED=[01], which causes go/build to select pure
	// Go/native implementations, respectively, based on build
	// tags.
	//
	// Each entry specifies a package-level object and the generic
	// file expected to define it when cgo is disabled.
	// When cgo is enabled, the exact file is not specified (since
	// it varies by platform), but must differ from the generic one.
	//
	// The test also loads the actual file to verify that the
	// object is indeed defined at that location.
	for _, test := range []struct {
		pkg, name, genericFile string
	}{
		{"net", "cgoLookupHost", "cgo_stub.go"},
		{"os/user", "current", "lookup_stubs.go"},
	} {
		ctxt := build.Default
		for _, ctxt.CgoEnabled = range []bool{false, true} {
			conf := loader.Config{Build: &ctxt}
			conf.Import(test.pkg)
			prog, err := conf.Load()
			if err != nil {
				t.Errorf("Load failed: %v", err)
				continue
			}
			info := prog.Imported[test.pkg]
			if info == nil {
				t.Errorf("package %s not found", test.pkg)
				continue
			}
			obj := info.Pkg.Scope().Lookup(test.name)
			if obj == nil {
				t.Errorf("no object %s.%s", test.pkg, test.name)
				continue
			}
			posn := prog.Fset.Position(obj.Pos())
			t.Logf("%s: %s (CgoEnabled=%t)", posn, obj, ctxt.CgoEnabled)

			gotFile := filepath.Base(posn.Filename)
			filesMatch := gotFile == test.genericFile

			if ctxt.CgoEnabled && filesMatch {
				t.Errorf("CGO_ENABLED=1: %s found in %s, want native file",
					obj, gotFile)
			} else if !ctxt.CgoEnabled && !filesMatch {
				t.Errorf("CGO_ENABLED=0: %s found in %s, want %s",
					obj, gotFile, test.genericFile)
			}

			// Load the file and check the object is declared at the right place.
			b, err := os.ReadFile(posn.Filename)
			if err != nil {
				t.Errorf("can't read %s: %s", posn.Filename, err)
				continue
			}
			line := string(bytes.Split(b, []byte("\n"))[posn.Line-1])
			ident := line[posn.Column-1:]
			if !strings.HasPrefix(ident, test.name) {
				t.Errorf("%s: %s not declared here (looking at %q)", posn, obj, ident)
			}
		}
	}
}


================================================
FILE: go/loader/testdata/a.go
================================================
package P


================================================
FILE: go/loader/testdata/b.go
================================================
package P


================================================
FILE: go/loader/testdata/badpkgdecl.go
================================================
// this file has no package decl


================================================
FILE: go/loader/testdata/issue46877/x.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package x

// #include "x.h"
import "C"

var _ C.myint


================================================
FILE: go/loader/testdata/issue46877/x.h
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

typedef int myint;


================================================
FILE: go/loader/util.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package loader

import (
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"io"
	"os"
	"strconv"
	"sync"

	"golang.org/x/tools/go/buildutil"
)

// We use a counting semaphore to limit
// the number of parallel I/O calls per process.
var ioLimit = make(chan bool, 10)

// parseFiles parses the Go source files within directory dir and
// returns the ASTs of the ones that could be at least partially parsed,
// along with a list of I/O and parse errors encountered.
//
// I/O is done via ctxt, which may specify a virtual file system.
// displayPath is used to transform the filenames attached to the ASTs.
func parseFiles(fset *token.FileSet, ctxt *build.Context, displayPath func(string) string, dir string, files []string, mode parser.Mode) ([]*ast.File, []error) {
	if displayPath == nil {
		displayPath = func(path string) string { return path }
	}
	var wg sync.WaitGroup
	n := len(files)
	parsed := make([]*ast.File, n)
	errors := make([]error, n)
	for i, file := range files {
		if !buildutil.IsAbsPath(ctxt, file) {
			file = buildutil.JoinPath(ctxt, dir, file)
		}
		wg.Add(1)
		go func(i int, file string) {
			ioLimit <- true // wait
			defer func() {
				wg.Done()
				<-ioLimit // signal
			}()
			var rd io.ReadCloser
			var err error
			if ctxt.OpenFile != nil {
				rd, err = ctxt.OpenFile(file)
			} else {
				rd, err = os.Open(file)
			}
			if err != nil {
				errors[i] = err // open failed
				return
			}

			// ParseFile may return both an AST and an error.
			parsed[i], errors[i] = parser.ParseFile(fset, displayPath(file), rd, mode)
			rd.Close()
		}(i, file)
	}
	wg.Wait()

	// Eliminate nils, preserving order.
	var o int
	for _, f := range parsed {
		if f != nil {
			parsed[o] = f
			o++
		}
	}
	parsed = parsed[:o]

	o = 0
	for _, err := range errors {
		if err != nil {
			errors[o] = err
			o++
		}
	}
	errors = errors[:o]

	return parsed, errors
}

// scanImports returns the set of all import paths from all
// import specs in the specified files.
func scanImports(files []*ast.File) map[string]bool {
	imports := make(map[string]bool)
	for _, f := range files {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT {
				for _, spec := range decl.Specs {
					spec := spec.(*ast.ImportSpec)

					// NB: do not assume the program is well-formed!
					path, err := strconv.Unquote(spec.Path.Value)
					if err != nil {
						continue // quietly ignore the error
					}
					if path == "C" {
						continue // skip pseudopackage
					}
					imports[path] = true
				}
			}
		}
	}
	return imports
}

// ---------- Internal helpers ----------

// TODO(adonovan): make this a method: func (*token.File) Contains(token.Pos)
func tokenFileContainsPos(f *token.File, pos token.Pos) bool {
	p := int(pos)
	base := f.Base()
	return base <= p && p < base+f.Size()
}


================================================
FILE: go/packages/doc.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package packages loads Go packages for inspection and analysis.

The [Load] function takes as input a list of patterns and returns a
list of [Package] values describing individual packages matched by those
patterns.
A [Config] specifies configuration options, the most important of which is
the [LoadMode], which controls the amount of detail in the loaded packages.

Load passes most patterns directly to the underlying build tool.
The default build tool is the go command.
Its supported patterns are described at
https://pkg.go.dev/cmd/go#hdr-Package_lists_and_patterns.
Other build systems may be supported by providing a "driver";
see [The driver protocol].

All patterns with the prefix "query=", where query is a
non-empty string of letters from [a-z], are reserved and may be
interpreted as query operators.

Two query operators are currently supported: "file" and "pattern".

The query "file=path/to/file.go" matches the package or packages enclosing
the Go source file path/to/file.go.  For example "file=~/go/src/fmt/print.go"
might return the packages "fmt" and "fmt [fmt.test]".

The query "pattern=string" causes "string" to be passed directly to
the underlying build tool. In most cases this is unnecessary,
but an application can use Load("pattern=" + x) as an escaping mechanism
to ensure that x is not interpreted as a query operator if it contains '='.

All other query operators are reserved for future use and currently
cause Load to report an error.

The Package struct provides basic information about the package, including

  - ID, a unique identifier for the package in the returned set;
  - GoFiles, the names of the package's Go source files;
  - Imports, a map from source import strings to the Packages they name;
  - Types, the type information for the package's exported symbols;
  - Syntax, the parsed syntax trees for the package's source code; and
  - TypesInfo, the result of a complete type-check of the package syntax trees.

(See the documentation for type Package for the complete list of fields
and more detailed descriptions.)

For example,

	Load(nil, "bytes", "unicode...")

returns four Package structs describing the standard library packages
bytes, unicode, unicode/utf16, and unicode/utf8. Note that one pattern
can match multiple packages and that a package might be matched by
multiple patterns: in general it is not possible to determine which
packages correspond to which patterns.

Note that the list returned by Load contains only the packages matched
by the patterns. Their dependencies can be found by walking the import
graph using the Imports fields.

The Load function can be configured by passing a pointer to a Config as
the first argument. A nil Config is equivalent to the zero Config, which
causes Load to run in [LoadFiles] mode, collecting minimal information.
See the documentation for type Config for details.

As noted earlier, the Config.Mode controls the amount of detail
reported about the loaded packages. See the documentation for type LoadMode
for details.

Most tools should pass their command-line arguments (after any flags)
uninterpreted to Load, so that it can interpret them
according to the conventions of the underlying build system.

See the Example function for typical usage.
See also [golang.org/x/tools/go/packages/internal/linecount]
for an example application.

# The driver protocol

Load may be used to load Go packages even in Go projects that use
alternative build systems, by installing an appropriate "driver"
program for the build system and specifying its location in the
GOPACKAGESDRIVER environment variable.
For example,
https://github.com/bazelbuild/rules_go/wiki/Editor-and-tool-integration
explains how to use the driver for Bazel.

The driver program is responsible for interpreting patterns in its
preferred notation and reporting information about the packages that
those patterns identify. Drivers must also support the special "file="
and "pattern=" patterns described above.

The patterns are provided as positional command-line arguments. A
JSON-encoded [DriverRequest] message providing additional information
is written to the driver's standard input. The driver must write a
JSON-encoded [DriverResponse] message to its standard output. (This
message differs from the JSON schema produced by 'go list'.)

The value of the PWD environment variable seen by the driver process
is the preferred name of its working directory. (The working directory
may have other aliases due to symbolic links; see the comment on the
Dir field of [exec.Cmd] for related information.)
When the driver process emits in its response the name of a file
that is a descendant of this directory, it must use an absolute path
that has the value of PWD as a prefix, to ensure that the returned
filenames satisfy the original query.
*/
package packages // import "golang.org/x/tools/go/packages"

/*

Motivation and design considerations

The new package's design solves problems addressed by two existing
packages: go/build, which locates and describes packages, and
golang.org/x/tools/go/loader, which loads, parses and type-checks them.
The go/build.Package structure encodes too much of the 'go build' way
of organizing projects, leaving us in need of a data type that describes a
package of Go source code independent of the underlying build system.
We wanted something that works equally well with go build and vgo, and
also other build systems such as Bazel and Blaze, making it possible to
construct analysis tools that work in all these environments.
Tools such as errcheck and staticcheck were essentially unavailable to
the Go community at Google, and some of Google's internal tools for Go
are unavailable externally.
This new package provides a uniform way to obtain package metadata by
querying each of these build systems, optionally supporting their
preferred command-line notations for packages, so that tools integrate
neatly with users' build environments. The Metadata query function
executes an external query tool appropriate to the current workspace.

Loading packages always returns the complete import graph "all the way down",
even if all you want is information about a single package, because the query
mechanisms of all the build systems we currently support ({go,vgo} list, and
blaze/bazel aspect-based query) cannot provide detailed information
about one package without visiting all its dependencies too, so there is
no additional asymptotic cost to providing transitive information.
(This property might not be true of a hypothetical 5th build system.)

In calls to TypeCheck, all initial packages, and any package that
transitively depends on one of them, must be loaded from source.
Consider A->B->C->D->E: if A,C are initial, A,B,C must be loaded from
source; D may be loaded from export data, and E may not be loaded at all
(though it's possible that D's export data mentions it, so a
types.Package may be created for it and exposed.)

The old loader had a feature to suppress type-checking of function
bodies on a per-package basis, primarily intended to reduce the work of
obtaining type information for imported packages. Now that imports are
satisfied by export data, the optimization no longer seems necessary.

Despite some early attempts, the old loader did not exploit export data,
instead always using the equivalent of WholeProgram mode. This was due
to the complexity of mixing source and export data packages (now
resolved by the upward traversal mentioned above), and because export data
files were nearly always missing or stale. Now that 'go build' supports
caching, all the underlying build systems can guarantee to produce
export data in a reasonable (amortized) time.

Test "main" packages synthesized by the build system are now reported as
first-class packages, avoiding the need for clients (such as go/ssa) to
reinvent this generation logic.

One way in which go/packages is simpler than the old loader is in its
treatment of in-package tests. In-package tests are packages that
consist of all the files of the library under test, plus the test files.
The old loader constructed in-package tests by a two-phase process of
mutation called "augmentation": first it would construct and type check
all the ordinary library packages and type-check the packages that
depend on them; then it would add more (test) files to the package and
type-check again. This two-phase approach had four major problems:
1) in processing the tests, the loader modified the library package,
   leaving no way for a client application to see both the test
   package and the library package; one would mutate into the other.
2) because test files can declare additional methods on types defined in
   the library portion of the package, the dispatch of method calls in
   the library portion was affected by the presence of the test files.
   This should have been a clue that the packages were logically
   different.
3) this model of "augmentation" assumed at most one in-package test
   per library package, which is true of projects using 'go build',
   but not other build systems.
4) because of the two-phase nature of test processing, all packages that
   import the library package had to be processed before augmentation,
   forcing a "one-shot" API and preventing the client from calling Load
   in several times in sequence as is now possible in WholeProgram mode.
   (TypeCheck mode has a similar one-shot restriction for a different reason.)

Early drafts of this package supported "multi-shot" operation.
Although it allowed clients to make a sequence of calls (or concurrent
calls) to Load, building up the graph of Packages incrementally,
it was of marginal value: it complicated the API
(since it allowed some options to vary across calls but not others),
it complicated the implementation,
it cannot be made to work in Types mode, as explained above,
and it was less efficient than making one combined call (when this is possible).
Among the clients we have inspected, none made multiple calls to load
but could not be easily and satisfactorily modified to make only a single call.
However, applications changes may be required.
For example, the ssadump command loads the user-specified packages
and in addition the runtime package.  It is tempting to simply append
"runtime" to the user-provided list, but that does not work if the user
specified an ad-hoc package such as [a.go b.go].
Instead, ssadump no longer requests the runtime package,
but seeks it among the dependencies of the user-specified packages,
and emits an error if it is not found.

Questions & Tasks

- Add GOARCH/GOOS?
  They are not portable concepts, but could be made portable.
  Our goal has been to allow users to express themselves using the conventions
  of the underlying build system: if the build system honors GOARCH
  during a build and during a metadata query, then so should
  applications built atop that query mechanism.
  Conversely, if the target architecture of the build is determined by
  command-line flags, the application can pass the relevant
  flags through to the build system using a command such as:
    myapp -query_flag="--cpu=amd64" -query_flag="--os=darwin"
  However, this approach is low-level, unwieldy, and non-portable.
  GOOS and GOARCH seem important enough to warrant a dedicated option.

- How should we handle partial failures such as a mixture of good and
  malformed patterns, existing and non-existent packages, successful and
  failed builds, import failures, import cycles, and so on, in a call to
  Load?

- Support bazel, blaze, and go1.10 list, not just go1.11 list.

- Handle (and test) various partial success cases, e.g.
  a mixture of good packages and:
  invalid patterns
  nonexistent packages
  empty packages
  packages with malformed package or import declarations
  unreadable files
  import cycles
  other parse errors
  type errors
  Make sure we record errors at the correct place in the graph.

- Missing packages among initial arguments are not reported.
  Return bogus packages for them, like golist does.

- "undeclared name" errors (for example) are reported out of source file
  order. I suspect this is due to the breadth-first resolution now used
  by go/types. Is that a bug? Discuss with gri.

*/


================================================
FILE: go/packages/example_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages_test

import (
	"flag"
	"fmt"
	"os"

	"golang.org/x/tools/go/packages"
)

// Example demonstrates how to load the packages specified on the
// command line from source syntax.
func Example() {
	flag.Parse()

	// Many tools pass their command-line arguments (after any flags)
	// uninterpreted to packages.Load so that it can interpret them
	// according to the conventions of the underlying build system.
	cfg := &packages.Config{Mode: packages.NeedFiles | packages.NeedSyntax}
	pkgs, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		fmt.Fprintf(os.Stderr, "load: %v\n", err)
		os.Exit(1)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}

	// Print the names of the source files
	// for each package listed on the command line.
	for _, pkg := range pkgs {
		fmt.Println(pkg.ID, pkg.GoFiles)
	}
}


================================================
FILE: go/packages/external.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

// This file defines the protocol that enables an external "driver"
// tool to supply package metadata in place of 'go list'.

import (
	"bytes"
	"encoding/json"
	"fmt"
	"os"
	"os/exec"
	"slices"
	"strings"
)

// DriverRequest defines the schema of a request for package metadata
// from an external driver program. The JSON-encoded DriverRequest
// message is provided to the driver program's standard input. The
// query patterns are provided as command-line arguments.
//
// See the package documentation for an overview.
type DriverRequest struct {
	Mode LoadMode `json:"mode"`

	// Env specifies the environment the underlying build system should be run in.
	Env []string `json:"env"`

	// BuildFlags are flags that should be passed to the underlying build system.
	BuildFlags []string `json:"build_flags"`

	// Tests specifies whether the patterns should also return test packages.
	Tests bool `json:"tests"`

	// Overlay maps file paths (relative to the driver's working directory)
	// to the contents of overlay files (see Config.Overlay).
	Overlay map[string][]byte `json:"overlay"`
}

// DriverResponse defines the schema of a response from an external
// driver program, providing the results of a query for package
// metadata. The driver program must write a JSON-encoded
// DriverResponse message to its standard output.
//
// See the package documentation for an overview.
type DriverResponse struct {
	// NotHandled is returned if the request can't be handled by the current
	// driver. If an external driver returns a response with NotHandled, the
	// rest of the DriverResponse is ignored, and go/packages will fallback
	// to the next driver. If go/packages is extended in the future to support
	// lists of multiple drivers, go/packages will fall back to the next driver.
	NotHandled bool

	// Compiler and Arch are the arguments pass of types.SizesFor
	// to get a types.Sizes to use when type checking.
	Compiler string
	Arch     string

	// Roots is the set of package IDs that make up the root packages.
	// We have to encode this separately because when we encode a single package
	// we cannot know if it is one of the roots as that requires knowledge of the
	// graph it is part of.
	Roots []string `json:",omitempty"`

	// Packages is the full set of packages in the graph.
	// The packages are not connected into a graph.
	// The Imports if populated will be stubs that only have their ID set.
	// Imports will be connected and then type and syntax information added in a
	// later pass (see refine).
	Packages []*Package

	// GoVersion is the minor version number used by the driver
	// (e.g. the go command on the PATH) when selecting .go files.
	// Zero means unknown.
	GoVersion int
}

// driver is the type for functions that query the build system for the
// packages named by the patterns.
type driver func(cfg *Config, patterns []string) (*DriverResponse, error)

// findExternalDriver returns the file path of a tool that supplies
// the build system package structure, or "" if not found.
// If GOPACKAGESDRIVER is set in the environment findExternalTool returns its
// value, otherwise it searches for a binary named gopackagesdriver on the PATH.
func findExternalDriver(cfg *Config) driver {
	const toolPrefix = "GOPACKAGESDRIVER="
	tool := ""
	for _, env := range cfg.Env {
		if val, ok := strings.CutPrefix(env, toolPrefix); ok {
			tool = val
		}
	}
	if tool != "" && tool == "off" {
		return nil
	}
	if tool == "" {
		var err error
		tool, err = exec.LookPath("gopackagesdriver")
		if err != nil {
			return nil
		}
	}
	return func(cfg *Config, patterns []string) (*DriverResponse, error) {
		req, err := json.Marshal(DriverRequest{
			Mode:       cfg.Mode,
			Env:        cfg.Env,
			BuildFlags: cfg.BuildFlags,
			Tests:      cfg.Tests,
			Overlay:    cfg.Overlay,
		})
		if err != nil {
			return nil, fmt.Errorf("failed to encode message to driver tool: %v", err)
		}

		buf := new(bytes.Buffer)
		stderr := new(bytes.Buffer)
		cmd := exec.CommandContext(cfg.Context, tool, patterns...)
		cmd.Dir = cfg.Dir
		// The cwd gets resolved to the real path. On Darwin, where
		// /tmp is a symlink, this breaks anything that expects the
		// working directory to keep the original path, including the
		// go command when dealing with modules.
		//
		// os.Getwd stdlib has a special feature where if the
		// cwd and the PWD are the same node then it trusts
		// the PWD, so by setting it in the env for the child
		// process we fix up all the paths returned by the go
		// command.
		//
		// (See similar trick in Invocation.run in ../../internal/gocommand/invoke.go)
		cmd.Env = append(slices.Clip(cfg.Env), "PWD="+cfg.Dir)
		cmd.Stdin = bytes.NewReader(req)
		cmd.Stdout = buf
		cmd.Stderr = stderr

		if err := cmd.Run(); err != nil {
			return nil, fmt.Errorf("%v: %v: %s", tool, err, cmd.Stderr)
		}
		if len(stderr.Bytes()) != 0 && os.Getenv("GOPACKAGESPRINTDRIVERERRORS") != "" {
			fmt.Fprintf(os.Stderr, "%s stderr: <<%s>>\n", cmdDebugStr(cmd), stderr)
		}

		var response DriverResponse
		if err := json.Unmarshal(buf.Bytes(), &response); err != nil {
			return nil, err
		}
		return &response, nil
	}
}


================================================
FILE: go/packages/golist.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"sync"
	"unicode"

	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/packagesinternal"
)

// debug controls verbose logging.
var debug, _ = strconv.ParseBool(os.Getenv("GOPACKAGESDEBUG"))

// A goTooOldError reports that the go command
// found by exec.LookPath is too old to use the new go list behavior.
type goTooOldError struct {
	error
}

// responseDeduper wraps a DriverResponse, deduplicating its contents.
type responseDeduper struct {
	seenRoots    map[string]bool
	seenPackages map[string]*Package
	dr           *DriverResponse
}

func newDeduper() *responseDeduper {
	return &responseDeduper{
		dr:           &DriverResponse{},
		seenRoots:    map[string]bool{},
		seenPackages: map[string]*Package{},
	}
}

// addAll fills in r with a DriverResponse.
func (r *responseDeduper) addAll(dr *DriverResponse) {
	for _, pkg := range dr.Packages {
		r.addPackage(pkg)
	}
	for _, root := range dr.Roots {
		r.addRoot(root)
	}
	r.dr.GoVersion = dr.GoVersion
}

func (r *responseDeduper) addPackage(p *Package) {
	if prev := r.seenPackages[p.ID]; prev != nil {
		// Package already seen in a previous response. Merge the file lists,
		// removing duplicates. This can happen when the same package appears
		// in multiple driver responses that are being merged together.
		prev.GoFiles = appendUniqueStrings(prev.GoFiles, p.GoFiles)
		prev.CompiledGoFiles = appendUniqueStrings(prev.CompiledGoFiles, p.CompiledGoFiles)
		prev.OtherFiles = appendUniqueStrings(prev.OtherFiles, p.OtherFiles)
		prev.IgnoredFiles = appendUniqueStrings(prev.IgnoredFiles, p.IgnoredFiles)
		prev.EmbedFiles = appendUniqueStrings(prev.EmbedFiles, p.EmbedFiles)
		prev.EmbedPatterns = appendUniqueStrings(prev.EmbedPatterns, p.EmbedPatterns)
		return
	}
	r.seenPackages[p.ID] = p
	r.dr.Packages = append(r.dr.Packages, p)
}

// appendUniqueStrings appends elements from src to dst, skipping duplicates.
func appendUniqueStrings(dst, src []string) []string {
	if len(src) == 0 {
		return dst
	}

	seen := make(map[string]bool, len(dst))
	for _, s := range dst {
		seen[s] = true
	}

	for _, s := range src {
		if !seen[s] {
			dst = append(dst, s)
		}
	}

	return dst
}

func (r *responseDeduper) addRoot(id string) {
	if r.seenRoots[id] {
		return
	}
	r.seenRoots[id] = true
	r.dr.Roots = append(r.dr.Roots, id)
}

type golistState struct {
	cfg *Config
	ctx context.Context

	runner *gocommand.Runner

	// overlay is the JSON file that encodes the Config.Overlay
	// mapping, used by 'go list -overlay=...'.
	overlay string

	envOnce    sync.Once
	goEnvError error
	goEnv      map[string]string

	rootsOnce     sync.Once
	rootDirsError error
	rootDirs      map[string]string

	goVersionOnce  sync.Once
	goVersionError error
	goVersion      int // The X in Go 1.X.

	// vendorDirs caches the (non)existence of vendor directories.
	vendorDirs map[string]bool
}

// getEnv returns Go environment variables. Only specific variables are
// populated -- computing all of them is slow.
func (state *golistState) getEnv() (map[string]string, error) {
	state.envOnce.Do(func() {
		var b *bytes.Buffer
		b, state.goEnvError = state.invokeGo("env", "-json", "GOMOD", "GOPATH")
		if state.goEnvError != nil {
			return
		}

		state.goEnv = make(map[string]string)
		decoder := json.NewDecoder(b)
		if state.goEnvError = decoder.Decode(&state.goEnv); state.goEnvError != nil {
			return
		}
	})
	return state.goEnv, state.goEnvError
}

// mustGetEnv is a convenience function that can be used if getEnv has already succeeded.
func (state *golistState) mustGetEnv() map[string]string {
	env, err := state.getEnv()
	if err != nil {
		panic(fmt.Sprintf("mustGetEnv: %v", err))
	}
	return env
}

// goListDriver uses the go list command to interpret the patterns and produce
// the build system package structure.
// See driver for more details.
//
// overlay is the JSON file that encodes the cfg.Overlay
// mapping, used by 'go list -overlay=...'
func goListDriver(cfg *Config, runner *gocommand.Runner, overlay string, patterns []string) (_ *DriverResponse, err error) {
	// Make sure that any asynchronous go commands are killed when we return.
	parentCtx := cfg.Context
	if parentCtx == nil {
		parentCtx = context.Background()
	}
	ctx, cancel := context.WithCancel(parentCtx)
	defer cancel()

	response := newDeduper()

	state := &golistState{
		cfg:        cfg,
		ctx:        ctx,
		vendorDirs: map[string]bool{},
		overlay:    overlay,
		runner:     runner,
	}

	// Fill in response.Sizes asynchronously if necessary.
	if cfg.Mode&NeedTypesSizes != 0 || cfg.Mode&(NeedTypes|NeedTypesInfo) != 0 {
		errCh := make(chan error)
		go func() {
			compiler, arch, err := getSizesForArgs(ctx, state.cfgInvocation(), runner)
			response.dr.Compiler = compiler
			response.dr.Arch = arch
			errCh <- err
		}()
		defer func() {
			if sizesErr := <-errCh; sizesErr != nil {
				err = sizesErr
			}
		}()
	}

	// Determine files requested in contains patterns
	var containFiles []string
	restPatterns := make([]string, 0, len(patterns))
	// Extract file= and other [querytype]= patterns. Report an error if querytype
	// doesn't exist.
extractQueries:
	for _, pattern := range patterns {
		eqidx := strings.Index(pattern, "=")
		if eqidx < 0 {
			restPatterns = append(restPatterns, pattern)
		} else {
			query, value := pattern[:eqidx], pattern[eqidx+len("="):]
			switch query {
			case "file":
				containFiles = append(containFiles, value)
			case "pattern":
				restPatterns = append(restPatterns, value)
			case "": // not a reserved query
				restPatterns = append(restPatterns, pattern)
			default:
				for _, rune := range query {
					if rune < 'a' || rune > 'z' { // not a reserved query
						restPatterns = append(restPatterns, pattern)
						continue extractQueries
					}
				}
				// Reject all other patterns containing "="
				return nil, fmt.Errorf("invalid query type %q in query pattern %q", query, pattern)
			}
		}
	}

	// See if we have any patterns to pass through to go list. Zero initial
	// patterns also requires a go list call, since it's the equivalent of
	// ".".
	if len(restPatterns) > 0 || len(patterns) == 0 {
		dr, err := state.createDriverResponse(restPatterns...)
		if err != nil {
			return nil, err
		}
		response.addAll(dr)
	}

	if len(containFiles) != 0 {
		if err := state.runContainsQueries(response, containFiles); err != nil {
			return nil, err
		}
	}

	// (We may yet return an error due to defer.)
	return response.dr, nil
}

// abs returns an absolute representation of path, based on cfg.Dir.
func (cfg *Config) abs(path string) (string, error) {
	if filepath.IsAbs(path) {
		return path, nil
	}
	// In case cfg.Dir is relative, pass it to filepath.Abs.
	return filepath.Abs(filepath.Join(cfg.Dir, path))
}

func (state *golistState) runContainsQueries(response *responseDeduper, queries []string) error {
	for _, query := range queries {
		// TODO(matloob): Do only one query per directory.
		fdir := filepath.Dir(query)
		// Pass absolute path of directory to go list so that it knows to treat it as a directory,
		// not a package path.
		pattern, err := state.cfg.abs(fdir)
		if err != nil {
			return fmt.Errorf("could not determine absolute path of file= query path %q: %v", query, err)
		}
		dirResponse, err := state.createDriverResponse(pattern)

		// If there was an error loading the package, or no packages are returned,
		// or the package is returned with errors, try to load the file as an
		// ad-hoc package.
		// Usually the error will appear in a returned package, but may not if we're
		// in module mode and the ad-hoc is located outside a module.
		if err != nil || len(dirResponse.Packages) == 0 || len(dirResponse.Packages) == 1 && len(dirResponse.Packages[0].GoFiles) == 0 &&
			len(dirResponse.Packages[0].Errors) == 1 {
			var queryErr error
			if dirResponse, queryErr = state.adhocPackage(pattern, query); queryErr != nil {
				return err // return the original error
			}
		}
		isRoot := make(map[string]bool, len(dirResponse.Roots))
		for _, root := range dirResponse.Roots {
			isRoot[root] = true
		}
		for _, pkg := range dirResponse.Packages {
			// Add any new packages to the main set
			// We don't bother to filter packages that will be dropped by the changes of roots,
			// that will happen anyway during graph construction outside this function.
			// Over-reporting packages is not a problem.
			response.addPackage(pkg)
			// if the package was not a root one, it cannot have the file
			if !isRoot[pkg.ID] {
				continue
			}
			for _, pkgFile := range pkg.GoFiles {
				if filepath.Base(query) == filepath.Base(pkgFile) {
					response.addRoot(pkg.ID)
					break
				}
			}
		}
	}
	return nil
}

// adhocPackage attempts to load or construct an ad-hoc package for a given
// query, if the original call to the driver produced inadequate results.
func (state *golistState) adhocPackage(pattern, query string) (*DriverResponse, error) {
	response, err := state.createDriverResponse(query)
	if err != nil {
		return nil, err
	}
	// If we get nothing back from `go list`,
	// try to make this file into its own ad-hoc package.
	// TODO(rstambler): Should this check against the original response?
	if len(response.Packages) == 0 {
		response.Packages = append(response.Packages, &Package{
			ID:              "command-line-arguments",
			PkgPath:         query,
			GoFiles:         []string{query},
			CompiledGoFiles: []string{query},
			Imports:         make(map[string]*Package),
		})
		response.Roots = append(response.Roots, "command-line-arguments")
	}
	// Handle special cases.
	if len(response.Packages) == 1 {
		// golang/go#33482: If this is a file= query for ad-hoc packages where
		// the file only exists on an overlay, and exists outside of a module,
		// add the file to the package and remove the errors.
		if response.Packages[0].ID == "command-line-arguments" ||
			filepath.ToSlash(response.Packages[0].PkgPath) == filepath.ToSlash(query) {
			if len(response.Packages[0].GoFiles) == 0 {
				filename := filepath.Join(pattern, filepath.Base(query)) // avoid recomputing abspath
				// TODO(matloob): check if the file is outside of a root dir?
				for path := range state.cfg.Overlay {
					if path == filename {
						response.Packages[0].Errors = nil
						response.Packages[0].GoFiles = []string{path}
						response.Packages[0].CompiledGoFiles = []string{path}
					}
				}
			}
		}
	}
	return response, nil
}

// Fields must match go list;
// see $GOROOT/src/cmd/go/internal/load/pkg.go.
type jsonPackage struct {
	ImportPath        string
	Dir               string
	Name              string
	Target            string
	Export            string
	GoFiles           []string
	CompiledGoFiles   []string
	IgnoredGoFiles    []string
	IgnoredOtherFiles []string
	EmbedPatterns     []string
	EmbedFiles        []string
	CFiles            []string
	CgoFiles          []string
	CXXFiles          []string
	MFiles            []string
	HFiles            []string
	FFiles            []string
	SFiles            []string
	SwigFiles         []string
	SwigCXXFiles      []string
	SysoFiles         []string
	Imports           []string
	ImportMap         map[string]string
	Deps              []string
	Module            *Module
	TestGoFiles       []string
	TestImports       []string
	XTestGoFiles      []string
	XTestImports      []string
	ForTest           string // q in a "p [q.test]" package, else ""
	DepOnly           bool

	Error      *packagesinternal.PackageError
	DepsErrors []*packagesinternal.PackageError
}

func otherFiles(p *jsonPackage) [][]string {
	return [][]string{p.CFiles, p.CXXFiles, p.MFiles, p.HFiles, p.FFiles, p.SFiles, p.SwigFiles, p.SwigCXXFiles, p.SysoFiles}
}

// createDriverResponse uses the "go list" command to expand the pattern
// words and return a response for the specified packages.
func (state *golistState) createDriverResponse(words ...string) (*DriverResponse, error) {
	// go list uses the following identifiers in ImportPath and Imports:
	//
	// 	"p"			-- importable package or main (command)
	// 	"q.test"		-- q's test executable
	// 	"p [q.test]"		-- variant of p as built for q's test executable
	// 	"q_test [q.test]"	-- q's external test package
	//
	// The packages p that are built differently for a test q.test
	// are q itself, plus any helpers used by the external test q_test,
	// typically including "testing" and all its dependencies.

	// Run "go list" for complete
	// information on the specified packages.
	goVersion, err := state.getGoVersion()
	if err != nil {
		return nil, err
	}
	buf, err := state.invokeGo("list", golistargs(state.cfg, words, goVersion)...)
	if err != nil {
		return nil, err
	}

	seen := make(map[string]*jsonPackage)
	pkgs := make(map[string]*Package)
	additionalErrors := make(map[string][]Error)
	// Decode the JSON and convert it to Package form.
	response := &DriverResponse{
		GoVersion: goVersion,
	}
	for dec := json.NewDecoder(buf); dec.More(); {
		p := new(jsonPackage)
		if err := dec.Decode(p); err != nil {
			return nil, fmt.Errorf("JSON decoding failed: %v", err)
		}

		if p.ImportPath == "" {
			// The documentation for go list says that “[e]rroneous packages will have
			// a non-empty ImportPath”. If for some reason it comes back empty, we
			// prefer to error out rather than silently discarding data or handing
			// back a package without any way to refer to it.
			if p.Error != nil {
				return nil, Error{
					Pos: p.Error.Pos,
					Msg: p.Error.Err,
				}
			}
			return nil, fmt.Errorf("package missing import path: %+v", p)
		}

		// Work around https://golang.org/issue/33157:
		// go list -e, when given an absolute path, will find the package contained at
		// that directory. But when no package exists there, it will return a fake package
		// with an error and the ImportPath set to the absolute path provided to go list.
		// Try to convert that absolute path to what its package path would be if it's
		// contained in a known module or GOPATH entry. This will allow the package to be
		// properly "reclaimed" when overlays are processed.
		if filepath.IsAbs(p.ImportPath) && p.Error != nil {
			pkgPath, ok, err := state.getPkgPath(p.ImportPath)
			if err != nil {
				return nil, err
			}
			if ok {
				p.ImportPath = pkgPath
			}
		}

		if old, found := seen[p.ImportPath]; found {
			// If one version of the package has an error, and the other doesn't, assume
			// that this is a case where go list is reporting a fake dependency variant
			// of the imported package: When a package tries to invalidly import another
			// package, go list emits a variant of the imported package (with the same
			// import path, but with an error on it, and the package will have a
			// DepError set on it). An example of when this can happen is for imports of
			// main packages: main packages can not be imported, but they may be
			// separately matched and listed by another pattern.
			// See golang.org/issue/36188 for more details.

			// The plan is that eventually, hopefully in Go 1.15, the error will be
			// reported on the importing package rather than the duplicate "fake"
			// version of the imported package. Once all supported versions of Go
			// have the new behavior this logic can be deleted.
			// TODO(matloob): delete the workaround logic once all supported versions of
			// Go return the errors on the proper package.

			// There should be exactly one version of a package that doesn't have an
			// error.
			if old.Error == nil && p.Error == nil {
				if !reflect.DeepEqual(p, old) {
					return nil, fmt.Errorf("internal error: go list gives conflicting information for package %v", p.ImportPath)
				}
				continue
			}

			// Determine if this package's error needs to be bubbled up.
			// This is a hack, and we expect for go list to eventually set the error
			// on the package.
			if old.Error != nil {
				var errkind string
				if strings.Contains(old.Error.Err, "not an importable package") {
					errkind = "not an importable package"
				} else if strings.Contains(old.Error.Err, "use of internal package") && strings.Contains(old.Error.Err, "not allowed") {
					errkind = "use of internal package not allowed"
				}
				if errkind != "" {
					if len(old.Error.ImportStack) < 1 {
						return nil, fmt.Errorf(`internal error: go list gave a %q error with empty import stack`, errkind)
					}
					importingPkg := old.Error.ImportStack[len(old.Error.ImportStack)-1]
					if importingPkg == old.ImportPath {
						// Using an older version of Go which put this package itself on top of import
						// stack, instead of the importer. Look for importer in second from top
						// position.
						if len(old.Error.ImportStack) < 2 {
							return nil, fmt.Errorf(`internal error: go list gave a %q error with an import stack without importing package`, errkind)
						}
						importingPkg = old.Error.ImportStack[len(old.Error.ImportStack)-2]
					}
					additionalErrors[importingPkg] = append(additionalErrors[importingPkg], Error{
						Pos:  old.Error.Pos,
						Msg:  old.Error.Err,
						Kind: ListError,
					})
				}
			}

			// Make sure that if there's a version of the package without an error,
			// that's the one reported to the user.
			if old.Error == nil {
				continue
			}

			// This package will replace the old one at the end of the loop.
		}
		seen[p.ImportPath] = p

		pkg := &Package{
			Name:            p.Name,
			ID:              p.ImportPath,
			Dir:             p.Dir,
			Target:          p.Target,
			GoFiles:         absJoin(p.Dir, p.GoFiles, p.CgoFiles),
			CompiledGoFiles: absJoin(p.Dir, p.CompiledGoFiles),
			OtherFiles:      absJoin(p.Dir, otherFiles(p)...),
			EmbedFiles:      absJoin(p.Dir, p.EmbedFiles),
			EmbedPatterns:   absJoin(p.Dir, p.EmbedPatterns),
			IgnoredFiles:    absJoin(p.Dir, p.IgnoredGoFiles, p.IgnoredOtherFiles),
			ForTest:         p.ForTest,
			depsErrors:      p.DepsErrors,
			Module:          p.Module,
		}

		if (state.cfg.Mode&typecheckCgo) != 0 && len(p.CgoFiles) != 0 {
			if len(p.CompiledGoFiles) > len(p.GoFiles) {
				// We need the cgo definitions, which are in the first
				// CompiledGoFile after the non-cgo ones. This is a hack but there
				// isn't currently a better way to find it. We also need the pure
				// Go files and unprocessed cgo files, all of which are already
				// in pkg.GoFiles.
				cgoTypes := p.CompiledGoFiles[len(p.GoFiles)]
				pkg.CompiledGoFiles = append([]string{cgoTypes}, pkg.GoFiles...)
			} else {
				// golang/go#38990: go list silently fails to do cgo processing
				pkg.CompiledGoFiles = nil
				pkg.Errors = append(pkg.Errors, Error{
					Msg:  "go list failed to return CompiledGoFiles. This may indicate failure to perform cgo processing; try building at the command line. See https://golang.org/issue/38990.",
					Kind: ListError,
				})
			}
		}

		// Work around https://golang.org/issue/28749:
		// cmd/go puts assembly, C, and C++ files in CompiledGoFiles.
		// Remove files from CompiledGoFiles that are non-go files
		// (or are not files that look like they are from the cache).
		if len(pkg.CompiledGoFiles) > 0 {
			out := pkg.CompiledGoFiles[:0]
			for _, f := range pkg.CompiledGoFiles {
				if ext := filepath.Ext(f); ext != ".go" && ext != "" { // ext == "" means the file is from the cache, so probably cgo-processed file
					continue
				}
				out = append(out, f)
			}
			pkg.CompiledGoFiles = out
		}

		// Extract the PkgPath from the package's ID.
		if i := strings.IndexByte(pkg.ID, ' '); i >= 0 {
			pkg.PkgPath = pkg.ID[:i]
		} else {
			pkg.PkgPath = pkg.ID
		}

		if pkg.PkgPath == "unsafe" {
			pkg.CompiledGoFiles = nil // ignore fake unsafe.go file (#59929)
		} else if len(pkg.CompiledGoFiles) == 0 {
			// Work around for pre-go.1.11 versions of go list.
			// TODO(matloob): they should be handled by the fallback.
			// Can we delete this?
			pkg.CompiledGoFiles = pkg.GoFiles
		}

		// Assume go list emits only absolute paths for Dir.
		if p.Dir != "" && !filepath.IsAbs(p.Dir) {
			log.Fatalf("internal error: go list returned non-absolute Package.Dir: %s", p.Dir)
		}

		if p.Export != "" && !filepath.IsAbs(p.Export) {
			pkg.ExportFile = filepath.Join(p.Dir, p.Export)
		} else {
			pkg.ExportFile = p.Export
		}

		// imports
		//
		// Imports contains the IDs of all imported packages.
		// ImportsMap records (path, ID) only where they differ.
		ids := make(map[string]bool)
		for _, id := range p.Imports {
			ids[id] = true
		}
		pkg.Imports = make(map[string]*Package)
		for path, id := range p.ImportMap {
			pkg.Imports[path] = &Package{ID: id} // non-identity import
			delete(ids, id)
		}
		for id := range ids {
			if id == "C" {
				continue
			}

			pkg.Imports[id] = &Package{ID: id} // identity import
		}
		if !p.DepOnly {
			response.Roots = append(response.Roots, pkg.ID)
		}

		// Temporary work-around for golang/go#39986. Parse filenames out of
		// error messages. This happens if there are unrecoverable syntax
		// errors in the source, so we can't match on a specific error message.
		//
		// TODO(rfindley): remove this heuristic, in favor of considering
		// InvalidGoFiles from the list driver.
		if err := p.Error; err != nil && state.shouldAddFilenameFromError(p) {
			addFilenameFromPos := func(pos string) bool {
				split := strings.Split(pos, ":")
				if len(split) < 1 {
					return false
				}
				filename := strings.TrimSpace(split[0])
				if filename == "" {
					return false
				}
				if !filepath.IsAbs(filename) {
					filename = filepath.Join(state.cfg.Dir, filename)
				}
				info, _ := os.Stat(filename)
				if info == nil {
					return false
				}
				pkg.CompiledGoFiles = append(pkg.CompiledGoFiles, filename)
				pkg.GoFiles = append(pkg.GoFiles, filename)
				return true
			}
			found := addFilenameFromPos(err.Pos)
			// In some cases, go list only reports the error position in the
			// error text, not the error position. One such case is when the
			// file's package name is a keyword (see golang.org/issue/39763).
			if !found {
				addFilenameFromPos(err.Err)
			}
		}

		if p.Error != nil {
			msg := strings.TrimSpace(p.Error.Err) // Trim to work around golang.org/issue/32363.
			// Address golang.org/issue/35964 by appending import stack to error message.
			if msg == "import cycle not allowed" && len(p.Error.ImportStack) != 0 {
				msg += fmt.Sprintf(": import stack: %v", p.Error.ImportStack)
			}
			pkg.Errors = append(pkg.Errors, Error{
				Pos:  p.Error.Pos,
				Msg:  msg,
				Kind: ListError,
			})
		}

		pkgs[pkg.ID] = pkg
	}

	for id, errs := range additionalErrors {
		if p, ok := pkgs[id]; ok {
			p.Errors = append(p.Errors, errs...)
		}
	}
	for _, pkg := range pkgs {
		response.Packages = append(response.Packages, pkg)
	}
	sort.Slice(response.Packages, func(i, j int) bool { return response.Packages[i].ID < response.Packages[j].ID })

	return response, nil
}

func (state *golistState) shouldAddFilenameFromError(p *jsonPackage) bool {
	if len(p.GoFiles) > 0 || len(p.CompiledGoFiles) > 0 {
		return false
	}

	goV, err := state.getGoVersion()
	if err != nil {
		return false
	}

	// On Go 1.14 and earlier, only add filenames from errors if the import stack is empty.
	// The import stack behaves differently for these versions than newer Go versions.
	if goV < 15 {
		return len(p.Error.ImportStack) == 0
	}

	// On Go 1.15 and later, only parse filenames out of error if there's no import stack,
	// or the current package is at the top of the import stack. This is not guaranteed
	// to work perfectly, but should avoid some cases where files in errors don't belong to this
	// package.
	return len(p.Error.ImportStack) == 0 || p.Error.ImportStack[len(p.Error.ImportStack)-1] == p.ImportPath
}

// getGoVersion returns the effective minor version of the go command.
func (state *golistState) getGoVersion() (int, error) {
	state.goVersionOnce.Do(func() {
		state.goVersion, state.goVersionError = gocommand.GoVersion(state.ctx, state.cfgInvocation(), state.runner)
	})
	return state.goVersion, state.goVersionError
}

// getPkgPath finds the package path of a directory if it's relative to a root
// directory.
func (state *golistState) getPkgPath(dir string) (string, bool, error) {
	if !filepath.IsAbs(dir) {
		panic("non-absolute dir passed to getPkgPath")
	}
	roots, err := state.determineRootDirs()
	if err != nil {
		return "", false, err
	}

	for rdir, rpath := range roots {
		// Make sure that the directory is in the module,
		// to avoid creating a path relative to another module.
		if !strings.HasPrefix(dir, rdir) {
			continue
		}
		// TODO(matloob): This doesn't properly handle symlinks.
		r, err := filepath.Rel(rdir, dir)
		if err != nil {
			continue
		}
		if rpath != "" {
			// We choose only one root even though the directory even it can belong in multiple modules
			// or GOPATH entries. This is okay because we only need to work with absolute dirs when a
			// file is missing from disk, for instance when gopls calls go/packages in an overlay.
			// Once the file is saved, gopls, or the next invocation of the tool will get the correct
			// result straight from golist.
			// TODO(matloob): Implement module tiebreaking?
			return path.Join(rpath, filepath.ToSlash(r)), true, nil
		}
		return filepath.ToSlash(r), true, nil
	}
	return "", false, nil
}

// absJoin absolutizes and flattens the lists of files.
func absJoin(dir string, fileses ...[]string) (res []string) {
	for _, files := range fileses {
		for _, file := range files {
			if !filepath.IsAbs(file) {
				file = filepath.Join(dir, file)
			}
			res = append(res, file)
		}
	}
	return res
}

func jsonFlag(cfg *Config, goVersion int) string {
	if goVersion < 19 {
		return "-json"
	}
	var fields []string
	added := make(map[string]bool)
	addFields := func(fs ...string) {
		for _, f := range fs {
			if !added[f] {
				added[f] = true
				fields = append(fields, f)
			}
		}
	}
	addFields("Name", "ImportPath", "Error") // These fields are always needed
	if cfg.Mode&NeedFiles != 0 || cfg.Mode&(NeedTypes|NeedTypesInfo) != 0 {
		addFields("Dir", "GoFiles", "IgnoredGoFiles", "IgnoredOtherFiles", "CFiles",
			"CgoFiles", "CXXFiles", "MFiles", "HFiles", "FFiles", "SFiles",
			"SwigFiles", "SwigCXXFiles", "SysoFiles")
		if cfg.Tests {
			addFields("TestGoFiles", "XTestGoFiles")
		}
	}
	if cfg.Mode&(NeedTypes|NeedTypesInfo) != 0 {
		// CompiledGoFiles seems to be required for the test case TestCgoNoSyntax,
		// even when -compiled isn't passed in.
		// TODO(#52435): Should we make the test ask for -compiled, or automatically
		// request CompiledGoFiles in certain circumstances?
		addFields("Dir", "CompiledGoFiles")
	}
	if cfg.Mode&NeedCompiledGoFiles != 0 {
		addFields("Dir", "CompiledGoFiles", "Export")
	}
	if cfg.Mode&NeedImports != 0 {
		// When imports are requested, DepOnly is used to distinguish between packages
		// explicitly requested and transitive imports of those packages.
		addFields("DepOnly", "Imports", "ImportMap")
		if cfg.Tests {
			addFields("TestImports", "XTestImports")
		}
	}
	if cfg.Mode&NeedDeps != 0 {
		addFields("DepOnly")
	}
	if usesExportData(cfg) {
		// Request Dir in the unlikely case Export is not absolute.
		addFields("Dir", "Export")
	}
	if cfg.Mode&NeedForTest != 0 {
		addFields("ForTest")
	}
	if cfg.Mode&needInternalDepsErrors != 0 {
		addFields("DepsErrors")
	}
	if cfg.Mode&NeedModule != 0 {
		addFields("Module")
	}
	if cfg.Mode&NeedEmbedFiles != 0 {
		addFields("EmbedFiles")
	}
	if cfg.Mode&NeedEmbedPatterns != 0 {
		addFields("EmbedPatterns")
	}
	if cfg.Mode&NeedTarget != 0 {
		addFields("Target")
	}
	return "-json=" + strings.Join(fields, ",")
}

func golistargs(cfg *Config, words []string, goVersion int) []string {
	const findFlags = NeedImports | NeedTypes | NeedSyntax | NeedTypesInfo
	fullargs := []string{
		"-e", jsonFlag(cfg, goVersion),
		fmt.Sprintf("-compiled=%t", cfg.Mode&(NeedCompiledGoFiles|NeedSyntax|NeedTypes|NeedTypesInfo|NeedTypesSizes) != 0),
		fmt.Sprintf("-test=%t", cfg.Tests),
		fmt.Sprintf("-export=%t", usesExportData(cfg)),
		fmt.Sprintf("-deps=%t", cfg.Mode&NeedImports != 0),
		// go list doesn't let you pass -test and -find together,
		// probably because you'd just get the TestMain.
		fmt.Sprintf("-find=%t", !cfg.Tests && cfg.Mode&findFlags == 0 && !usesExportData(cfg)),
		// VCS information is not needed when not printing Stale or StaleReason fields
		"-buildvcs=false",
	}

	// golang/go#60456: with go1.21 and later, go list serves pgo variants, which
	// can be costly to compute and may result in redundant processing for the
	// caller. Disable these variants. If someone wants to add e.g. a NeedPGO
	// mode flag, that should be a separate proposal.
	if goVersion >= 21 {
		fullargs = append(fullargs, "-pgo=off")
	}

	fullargs = append(fullargs, cfg.BuildFlags...)
	fullargs = append(fullargs, "--")
	fullargs = append(fullargs, words...)
	return fullargs
}

// cfgInvocation returns an Invocation that reflects cfg's settings.
func (state *golistState) cfgInvocation() gocommand.Invocation {
	cfg := state.cfg
	return gocommand.Invocation{
		BuildFlags: cfg.BuildFlags,
		CleanEnv:   cfg.Env != nil,
		Env:        cfg.Env,
		Logf:       cfg.Logf,
		WorkingDir: cfg.Dir,
		Overlay:    state.overlay,
	}
}

// invokeGo returns the stdout of a go command invocation.
func (state *golistState) invokeGo(verb string, args ...string) (*bytes.Buffer, error) {
	cfg := state.cfg

	inv := state.cfgInvocation()
	inv.Verb = verb
	inv.Args = args

	stdout, stderr, friendlyErr, err := state.runner.RunRaw(cfg.Context, inv)
	if err != nil {
		// Check for 'go' executable not being found.
		if ee, ok := err.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
			return nil, fmt.Errorf("'go list' driver requires 'go', but %s", exec.ErrNotFound)
		}

		exitErr, ok := err.(*exec.ExitError)
		if !ok {
			// Catastrophic error:
			// - context cancellation
			return nil, fmt.Errorf("couldn't run 'go': %w", err)
		}

		// Old go version?
		if strings.Contains(stderr.String(), "flag provided but not defined") {
			return nil, goTooOldError{fmt.Errorf("unsupported version of go: %s: %s", exitErr, stderr)}
		}

		// Related to #24854
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "unexpected directory layout") {
			return nil, friendlyErr
		}

		// Return an error if 'go list' failed due to missing tools in
		// $GOROOT/pkg/tool/$GOOS_$GOARCH (#69606).
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), `go: no such tool`) {
			return nil, friendlyErr
		}

		// Is there an error running the C compiler in cgo? This will be reported in the "Error" field
		// and should be suppressed by go list -e.
		//
		// This condition is not perfect yet because the error message can include other error messages than runtime/cgo.
		isPkgPathRune := func(r rune) bool {
			// From https://golang.org/ref/spec#Import_declarations:
			//    Implementation restriction: A compiler may restrict ImportPaths to non-empty strings
			//    using only characters belonging to Unicode's L, M, N, P, and S general categories
			//    (the Graphic characters without spaces) and may also exclude the
			//    characters !"#$%&'()*,:;<=>?[\]^`{|} and the Unicode replacement character U+FFFD.
			return unicode.IsOneOf([]*unicode.RangeTable{unicode.L, unicode.M, unicode.N, unicode.P, unicode.S}, r) &&
				!strings.ContainsRune("!\"#$%&'()*,:;<=>?[\\]^`{|}\uFFFD", r)
		}
		// golang/go#36770: Handle case where cmd/go prints module download messages before the error.
		msg := stderr.String()
		for strings.HasPrefix(msg, "go: downloading") {
			msg = msg[strings.IndexRune(msg, '\n')+1:]
		}
		if len(stderr.String()) > 0 && strings.HasPrefix(stderr.String(), "# ") {
			msg := msg[len("# "):]
			if strings.HasPrefix(strings.TrimLeftFunc(msg, isPkgPathRune), "\n") {
				return stdout, nil
			}
			// Treat pkg-config errors as a special case (golang.org/issue/36770).
			if strings.HasPrefix(msg, "pkg-config") {
				return stdout, nil
			}
		}

		// This error only appears in stderr. See golang.org/cl/166398 for a fix in go list to show
		// the error in the Err section of stdout in case -e option is provided.
		// This fix is provided for backwards compatibility.
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "named files must be .go files") {
			output := fmt.Sprintf(`{"ImportPath": "command-line-arguments","Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Similar to the previous error, but currently lacks a fix in Go.
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "named files must all be in one directory") {
			output := fmt.Sprintf(`{"ImportPath": "command-line-arguments","Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Backwards compatibility for Go 1.11 because 1.12 and 1.13 put the directory in the ImportPath.
		// If the package doesn't exist, put the absolute path of the directory into the error message,
		// as Go 1.13 list does.
		const noSuchDirectory = "no such directory"
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), noSuchDirectory) {
			errstr := stderr.String()
			abspath := strings.TrimSpace(errstr[strings.Index(errstr, noSuchDirectory)+len(noSuchDirectory):])
			output := fmt.Sprintf(`{"ImportPath": %q,"Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				abspath, strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Workaround for #29280: go list -e has incorrect behavior when an ad-hoc package doesn't exist.
		// Note that the error message we look for in this case is different that the one looked for above.
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "no such file or directory") {
			output := fmt.Sprintf(`{"ImportPath": "command-line-arguments","Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Workaround for #34273. go list -e with GO111MODULE=on has incorrect behavior when listing a
		// directory outside any module.
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "outside available modules") {
			output := fmt.Sprintf(`{"ImportPath": %q,"Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				// TODO(matloob): command-line-arguments isn't correct here.
				"command-line-arguments", strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Another variation of the previous error
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "outside module root") {
			output := fmt.Sprintf(`{"ImportPath": %q,"Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				// TODO(matloob): command-line-arguments isn't correct here.
				"command-line-arguments", strings.Trim(stderr.String(), "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Workaround for an instance of golang.org/issue/26755: go list -e  will return a non-zero exit
		// status if there's a dependency on a package that doesn't exist. But it should return
		// a zero exit status and set an error on that package.
		if len(stderr.String()) > 0 && strings.Contains(stderr.String(), "no Go files in") {
			// Don't clobber stdout if `go list` actually returned something.
			if len(stdout.String()) > 0 {
				return stdout, nil
			}
			// try to extract package name from string
			stderrStr := stderr.String()
			var importPath string
			colon := strings.Index(stderrStr, ":")
			if colon > 0 && strings.HasPrefix(stderrStr, "go build ") {
				importPath = stderrStr[len("go build "):colon]
			}
			output := fmt.Sprintf(`{"ImportPath": %q,"Incomplete": true,"Error": {"Pos": "","Err": %q}}`,
				importPath, strings.Trim(stderrStr, "\n"))
			return bytes.NewBufferString(output), nil
		}

		// Export mode entails a build.
		// If that build fails, errors appear on stderr
		// (despite the -e flag) and the Export field is blank.
		// Do not fail in that case.
		// The same is true if an ad-hoc package given to go list doesn't exist.
		// TODO(matloob): Remove these once we can depend on go list to exit with a zero status with -e even when
		// packages don't exist or a build fails.
		if !usesExportData(cfg) && !containsGoFile(args) {
			return nil, friendlyErr
		}
	}
	return stdout, nil
}

func containsGoFile(s []string) bool {
	for _, f := range s {
		if strings.HasSuffix(f, ".go") {
			return true
		}
	}
	return false
}

func cmdDebugStr(cmd *exec.Cmd) string {
	env := make(map[string]string)
	for _, kv := range cmd.Env {
		split := strings.SplitN(kv, "=", 2)
		k, v := split[0], split[1]
		env[k] = v
	}

	var args []string
	for _, arg := range cmd.Args {
		quoted := strconv.Quote(arg)
		if quoted[1:len(quoted)-1] != arg || strings.Contains(arg, " ") {
			args = append(args, quoted)
		} else {
			args = append(args, arg)
		}
	}
	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], strings.Join(args, " "))
}

// getSizesForArgs queries 'go list' for the appropriate
// Compiler and GOARCH arguments to pass to [types.SizesFor].
func getSizesForArgs(ctx context.Context, inv gocommand.Invocation, gocmdRunner *gocommand.Runner) (string, string, error) {
	inv.Verb = "list"
	inv.Args = []string{"-f", "{{context.GOARCH}} {{context.Compiler}}", "--", "unsafe"}
	stdout, stderr, friendlyErr, rawErr := gocmdRunner.RunRaw(ctx, inv)
	var goarch, compiler string
	if rawErr != nil {
		rawErrMsg := rawErr.Error()
		if strings.Contains(rawErrMsg, "cannot find main module") ||
			strings.Contains(rawErrMsg, "go.mod file not found") {
			// User's running outside of a module.
			// All bets are off. Get GOARCH and guess compiler is gc.
			// TODO(matloob): Is this a problem in practice?
			inv.Verb = "env"
			inv.Args = []string{"GOARCH"}
			envout, enverr := gocmdRunner.Run(ctx, inv)
			if enverr != nil {
				return "", "", enverr
			}
			goarch = strings.TrimSpace(envout.String())
			compiler = "gc"
		} else if friendlyErr != nil {
			return "", "", friendlyErr
		} else {
			// This should be unreachable, but be defensive
			// in case RunRaw's error results are inconsistent.
			return "", "", rawErr
		}
	} else {
		fields := strings.Fields(stdout.String())
		if len(fields) < 2 {
			return "", "", fmt.Errorf("could not parse GOARCH and Go compiler in format \"<GOARCH> <compiler>\":\nstdout: <<%s>>\nstderr: <<%s>>",
				stdout.String(), stderr.String())
		}
		goarch = fields[0]
		compiler = fields[1]
	}
	return compiler, goarch, nil
}


================================================
FILE: go/packages/golist_overlay.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

import (
	"encoding/json"
	"path/filepath"

	"golang.org/x/tools/internal/gocommand"
)

// determineRootDirs returns a mapping from absolute directories that could
// contain code to their corresponding import path prefixes.
func (state *golistState) determineRootDirs() (map[string]string, error) {
	env, err := state.getEnv()
	if err != nil {
		return nil, err
	}
	if env["GOMOD"] != "" {
		state.rootsOnce.Do(func() {
			state.rootDirs, state.rootDirsError = state.determineRootDirsModules()
		})
	} else {
		state.rootsOnce.Do(func() {
			state.rootDirs, state.rootDirsError = state.determineRootDirsGOPATH()
		})
	}
	return state.rootDirs, state.rootDirsError
}

func (state *golistState) determineRootDirsModules() (map[string]string, error) {
	// List all of the modules--the first will be the directory for the main
	// module. Any replaced modules will also need to be treated as roots.
	// Editing files in the module cache isn't a great idea, so we don't
	// plan to ever support that.
	out, err := state.invokeGo("list", "-m", "-json", "all")
	if err != nil {
		// 'go list all' will fail if we're outside of a module and
		// GO111MODULE=on. Try falling back without 'all'.
		var innerErr error
		out, innerErr = state.invokeGo("list", "-m", "-json")
		if innerErr != nil {
			return nil, err
		}
	}
	roots := map[string]string{}
	modules := map[string]string{}
	var i int
	for dec := json.NewDecoder(out); dec.More(); {
		mod := new(gocommand.ModuleJSON)
		if err := dec.Decode(mod); err != nil {
			return nil, err
		}
		if mod.Dir != "" && mod.Path != "" {
			// This is a valid module; add it to the map.
			absDir, err := state.cfg.abs(mod.Dir)
			if err != nil {
				return nil, err
			}
			modules[absDir] = mod.Path
			// The first result is the main module.
			if i == 0 || mod.Replace != nil && mod.Replace.Path != "" {
				roots[absDir] = mod.Path
			}
		}
		i++
	}
	return roots, nil
}

func (state *golistState) determineRootDirsGOPATH() (map[string]string, error) {
	m := map[string]string{}
	for _, dir := range filepath.SplitList(state.mustGetEnv()["GOPATH"]) {
		absDir, err := filepath.Abs(dir)
		if err != nil {
			return nil, err
		}
		m[filepath.Join(absDir, "src")] = ""
	}
	return m, nil
}


================================================
FILE: go/packages/gopackages/main.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The gopackages command is a diagnostic tool that demonstrates
// how to use golang.org/x/tools/go/packages to load, parse,
// type-check, and print one or more Go packages.
// Its precise output is unspecified and may change.
package main

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"go/types"
	"log"
	"os"
	"sort"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/drivertest"
	"golang.org/x/tools/internal/tool"
)

func main() {
	drivertest.RunIfChild()
	tool.Main(context.Background(), &application{Mode: "imports"}, os.Args[1:])
}

type application struct {
	// Embed the basic profiling flags supported by the tool package
	tool.Profile

	Deps       bool            `flag:"deps" help:"show dependencies too"`
	Test       bool            `flag:"test" help:"include any tests implied by the patterns"`
	Mode       string          `flag:"mode" help:"mode (one of files, imports, types, syntax, allsyntax)"`
	Tags       string          `flag:"tags" help:"comma-separated list of extra build tags (see: go help buildconstraint)"`
	Private    bool            `flag:"private" help:"show non-exported declarations too (if -mode=syntax)"`
	PrintJSON  bool            `flag:"json" help:"print package in JSON form"`
	BuildFlags stringListValue `flag:"buildflag" help:"pass argument to underlying build system (may be repeated)"`
	Driver     bool            `flag:"driver" help:"use golist passthrough driver (for debugging driver issues)"`
}

// Name implements tool.Application returning the binary name.
func (app *application) Name() string { return "gopackages" }

// Usage implements tool.Application returning empty extra argument usage.
func (app *application) Usage() string { return "package..." }

// ShortHelp implements tool.Application returning the main binary help.
func (app *application) ShortHelp() string {
	return "gopackages loads, parses, type-checks, and prints one or more Go packages."
}

// DetailedHelp implements tool.Application returning the main binary help.
func (app *application) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Packages are specified using the notation of "go list",
or other underlying build system.

The mode flag determines how much information is computed and printed
for the specified packages. In order of increasing computational cost,
the legal values are:

 -mode=files     shows only the names of the packages' files.
 -mode=imports   also shows the imports. (This is the default.)
 -mode=types     loads the compiler's export data and displays the
                 type of each exported declaration.
 -mode=syntax    parses and type checks syntax trees for the initial
                 packages. (With the -private flag, the types of
                 non-exported declarations are shown too.)
                 Type information for dependencies is obtained from
                 compiler export data.
 -mode=allsyntax is like -mode=syntax but applied to all dependencies.

Flags:
`)
	f.PrintDefaults()
}

// Run takes the args after flag processing and performs the specified query.
func (app *application) Run(ctx context.Context, args ...string) error {
	if len(args) == 0 {
		return tool.CommandLineErrorf("not enough arguments")
	}

	env := os.Environ()
	if app.Driver {
		env = append(env, drivertest.Env(log.Default())...)
	}

	// Load, parse, and type-check the packages named on the command line.
	cfg := &packages.Config{
		Mode:       packages.LoadSyntax,
		Tests:      app.Test,
		BuildFlags: append([]string{"-tags=" + app.Tags}, app.BuildFlags...),
		Env:        env,
	}

	// -mode flag
	switch strings.ToLower(app.Mode) {
	case "files":
		cfg.Mode = packages.LoadFiles
	case "imports":
		cfg.Mode = packages.LoadImports
	case "types":
		cfg.Mode = packages.LoadTypes
	case "syntax":
		cfg.Mode = packages.LoadSyntax
	case "allsyntax":
		cfg.Mode = packages.LoadAllSyntax
	default:
		return tool.CommandLineErrorf("invalid mode: %s", app.Mode)
	}
	cfg.Mode |= packages.NeedModule

	lpkgs, err := packages.Load(cfg, args...)
	if err != nil {
		return err
	}

	// -deps: print dependencies too.
	if app.Deps {
		// We can't use packages.All because
		// we need an ordered traversal.
		var all []*packages.Package // postorder
		seen := make(map[*packages.Package]bool)
		var visit func(*packages.Package)
		visit = func(lpkg *packages.Package) {
			if !seen[lpkg] {
				seen[lpkg] = true

				// visit imports
				var importPaths []string
				for path := range lpkg.Imports {
					importPaths = append(importPaths, path)
				}
				sort.Strings(importPaths) // for determinism
				for _, path := range importPaths {
					visit(lpkg.Imports[path])
				}

				all = append(all, lpkg)
			}
		}
		for _, lpkg := range lpkgs {
			visit(lpkg)
		}
		lpkgs = all
	}

	for _, lpkg := range lpkgs {
		app.print(lpkg)
	}
	return nil
}

func (app *application) print(lpkg *packages.Package) {
	if app.PrintJSON {
		data, _ := json.MarshalIndent(lpkg, "", "\t")
		os.Stdout.Write(data)
		return
	}
	// title
	var kind string
	// TODO(matloob): If IsTest is added back print "test command" or
	// "test package" for packages with IsTest == true.
	if lpkg.Name == "main" {
		kind += "command"
	} else {
		kind += "package"
	}
	fmt.Printf("Go %s %q:\n", kind, lpkg.ID) // unique ID
	if mod := lpkg.Module; mod != nil {
		fmt.Printf("\tmodule %s@%s\n", mod.Path, mod.Version)
	}
	fmt.Printf("\tpackage %s\n", lpkg.Name)

	// characterize type info
	if lpkg.Types == nil {
		fmt.Printf("\thas no exported type info\n")
	} else if !lpkg.Types.Complete() {
		fmt.Printf("\thas incomplete exported type info\n")
	} else if len(lpkg.Syntax) == 0 {
		fmt.Printf("\thas complete exported type info\n")
	} else {
		fmt.Printf("\thas complete exported type info and typed ASTs\n")
	}
	if lpkg.Types != nil && lpkg.IllTyped && len(lpkg.Errors) == 0 {
		fmt.Printf("\thas an error among its dependencies\n")
	}

	// source files
	for _, src := range lpkg.GoFiles {
		fmt.Printf("\tfile %s\n", src)
	}

	// imports
	var lines []string
	for importPath, imp := range lpkg.Imports {
		var line string
		if imp.ID == importPath {
			line = fmt.Sprintf("\timport %q", importPath)
		} else {
			line = fmt.Sprintf("\timport %q => %q", importPath, imp.ID)
		}
		lines = append(lines, line)
	}
	sort.Strings(lines)
	for _, line := range lines {
		fmt.Println(line)
	}

	// errors
	for _, err := range lpkg.Errors {
		fmt.Printf("\t%s\n", err)
	}

	// types of package members
	if lpkg.Types != nil {
		qual := types.RelativeTo(lpkg.Types)
		scope := lpkg.Types.Scope()
		for _, name := range scope.Names() {
			obj := scope.Lookup(name)
			if !obj.Exported() && !app.Private {
				continue // skip unexported names
			}

			fmt.Printf("\t%s\n", types.ObjectString(obj, qual))
			if _, ok := obj.(*types.TypeName); ok {
				for _, meth := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
					if !meth.Obj().Exported() && !app.Private {
						continue // skip unexported names
					}
					fmt.Printf("\t%s\n", types.SelectionString(meth, qual))
				}
			}
		}
	}

	fmt.Println()
}

// stringListValue is a flag.Value that accumulates strings.
// e.g. --flag=one --flag=two would produce []string{"one", "two"}.
type stringListValue []string

func (ss *stringListValue) Get() any { return []string(*ss) }

func (ss *stringListValue) String() string { return fmt.Sprintf("%q", *ss) }

func (ss *stringListValue) Set(s string) error { *ss = append(*ss, s); return nil }


================================================
FILE: go/packages/internal/linecount/linecount.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The linecount command shows the number of lines of code in a set of
// Go packages plus their dependencies. It serves as a working
// illustration of the [packages.Load] operation.
//
// Example: show gopls' total source line count, and its breakdown
// between gopls, x/tools, and the std go/* packages. (The balance
// comes from other std packages, other x/ repos, and external
// dependencies.)
//
//	$ linecount -mode=total ./gopls
//	752124
//	$ linecount -mode=total -module=golang.org/x/tools/gopls ./gopls
//	103519
//	$ linecount -mode=total -module=golang.org/x/tools ./gopls
//	99504
//	$ linecount -mode=total -prefix=go -module=std ./gopls
//	47502
//
// Example: show the top 5 modules contributing to gopls' source line count:
//
//	$ linecount -mode=module ./gopls | head -n 5
//	440274	std
//	103519	golang.org/x/tools/gopls
//	99504	golang.org/x/tools
//	40220	honnef.co/go/tools
//	17707	golang.org/x/text
//
// Example: show the top 3 largest files in the gopls module:
//
//	$ linecount -mode=file -module=golang.org/x/tools/gopls ./gopls | head -n 3
//	6841	gopls/internal/protocol/tsprotocol.go
//	3769	gopls/internal/golang/completion/completion.go
//	2202	gopls/internal/cache/snapshot.go
package main

import (
	"bytes"
	"cmp"
	"flag"
	"fmt"
	"go/scanner"
	"go/token"
	"log"
	"os"
	"path"
	"slices"
	"strings"
	"sync"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/packages"
)

// TODO(adonovan): filters:
// - exclude generated files (-generated=false)
// - exclude non-CompiledGoFiles
// - include OtherFiles (asm, etc)
// - include tests (needs care to avoid double counting)

func usage() {
	// See https://go.dev/issue/63659.
	fmt.Fprintf(os.Stderr, "Usage: linecount [flags] packages...\n")
	flag.PrintDefaults()
	fmt.Fprintf(os.Stderr, `
Docs: go doc golang.org/x/tools/go/packages/internal/linecount
https://pkg.go.dev/golang.org/x/tools/go/packages/internal/linecount
`)
}

func main() {
	// Parse command line.
	log.SetPrefix("linecount: ")
	log.SetFlags(0)
	var (
		mode       = flag.String("mode", "file", "group lines by 'module', 'package', or 'file', or show only 'total'")
		prefix     = flag.String("prefix", "", "count files only in packages whose path has the specified prefix")
		onlyModule = flag.String("module", "", "count files only in the specified module")
		nonblank   = flag.Bool("nonblank", false, "count only non-comment, non-blank lines")
	)
	flag.Usage = usage
	flag.Parse()
	if len(flag.Args()) == 0 {
		usage()
		os.Exit(1)
	}

	// Load packages.
	cfg := &packages.Config{
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedImports |
			packages.NeedDeps |
			packages.NeedModule,
	}
	pkgs, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		log.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}

	// Read files and count lines.
	var (
		mu        sync.Mutex
		byFile    = make(map[string]int)
		byPackage = make(map[string]int)
		byModule  = make(map[string]int)
	)
	var g errgroup.Group
	g.SetLimit(20) // file system parallelism level
	packages.Visit(pkgs, nil, func(p *packages.Package) {
		pkgpath := p.PkgPath
		module := "std"
		if p.Module != nil {
			module = p.Module.Path
		}
		if *prefix != "" && !within(pkgpath, path.Clean(*prefix)) {
			return
		}
		if *onlyModule != "" && module != *onlyModule {
			return
		}
		for _, f := range p.GoFiles {
			g.Go(func() error {
				data, err := os.ReadFile(f)
				if err != nil {
					return err
				}

				n := count(*nonblank, data)

				mu.Lock()
				byFile[f] = n
				byPackage[pkgpath] += n
				byModule[module] += n
				mu.Unlock()

				return nil
			})
		}
	})
	if err := g.Wait(); err != nil {
		log.Fatal(err)
	}

	// Display the result.
	switch *mode {
	case "file", "package", "module":
		var m map[string]int
		switch *mode {
		case "file":
			m = byFile
		case "package":
			m = byPackage
		case "module":
			m = byModule
		}
		type item struct {
			name  string
			count int
		}
		var items []item
		for name, count := range m {
			items = append(items, item{name, count})
		}
		slices.SortFunc(items, func(x, y item) int {
			return -cmp.Compare(x.count, y.count)
		})
		for _, item := range items {
			fmt.Printf("%d\t%s\n", item.count, item.name)
		}

	case "total":
		total := 0
		for _, n := range byFile {
			total += n
		}
		fmt.Printf("%d\n", total)

	default:
		log.Fatalf("invalid -mode %q (want file, package, module, or total)", *mode)
	}
}

func within(file, dir string) bool {
	return file == dir ||
		strings.HasPrefix(file, dir) && file[len(dir)] == os.PathSeparator
}

// count counts lines, or non-comment non-blank lines.
func count(nonblank bool, src []byte) int {
	if nonblank {
		// Count distinct lines containing tokens.
		var (
			fset     = token.NewFileSet()
			f        = fset.AddFile("", fset.Base(), len(src))
			prevLine = 0
			count    = 0
			scan     scanner.Scanner
		)
		scan.Init(f, src, nil, 0)
		for {
			pos, tok, _ := scan.Scan()
			if tok == token.EOF {
				break
			}
			// This may be slow because it binary
			// searches the newline offset table.
			line := f.PositionFor(pos, false).Line // ignore //line directives
			if line > prevLine {
				prevLine = line
				count++
			}
		}
		return count
	}

	// Count all lines.
	return bytes.Count(src, []byte("\n"))
}


================================================
FILE: go/packages/internal/nodecount/nodecount.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The nodecount program illustrates the use of packages.Load to print
// the frequency of occurrence of each type of syntax node among the
// selected packages.
//
// Example usage:
//
//	$ nodecount golang.org/x/tools/... std
//
// A typical distribution is 40% identifiers, 10% literals, 8%
// selectors, and 6% calls; around 3% each of BinaryExpr, BlockStmt,
// AssignStmt, Field, and Comment; and the rest accounting for 20%.
package main

import (
	"flag"
	"fmt"
	"go/ast"
	"log"
	"reflect"
	"sort"

	"golang.org/x/tools/go/packages"
)

func main() {
	flag.Parse()

	// Parse specified packages.
	config := packages.Config{
		Mode:  packages.NeedSyntax | packages.NeedFiles,
		Tests: true,
	}
	pkgs, err := packages.Load(&config, flag.Args()...)
	if err != nil {
		log.Fatal(err)
	}

	// Count each type of syntax node.
	var (
		byType = make(map[reflect.Type]int)
		total  int
	)
	packages.Visit(pkgs, nil, func(p *packages.Package) {
		for _, f := range p.Syntax {
			ast.Inspect(f, func(n ast.Node) bool {
				if n != nil {
					byType[reflect.TypeOf(n)]++
					total++
				}
				return true
			})
		}
	})

	// Print results (percent, count, type) in descending order.
	var types []reflect.Type
	for t := range byType {
		types = append(types, t)
	}
	sort.Slice(types, func(i, j int) bool {
		return byType[types[i]] > byType[types[j]]
	})
	for _, t := range types {
		percent := 100 * float64(byType[t]) / float64(total)
		fmt.Printf("%6.2f%%\t%8d\t%s\n", percent, byType[t], t)
	}
}


================================================
FILE: go/packages/loadmode_string.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

import (
	"fmt"
	"strings"
)

var modes = [...]struct {
	mode LoadMode
	name string
}{
	{NeedName, "NeedName"},
	{NeedFiles, "NeedFiles"},
	{NeedCompiledGoFiles, "NeedCompiledGoFiles"},
	{NeedImports, "NeedImports"},
	{NeedDeps, "NeedDeps"},
	{NeedExportFile, "NeedExportFile"},
	{NeedTypes, "NeedTypes"},
	{NeedSyntax, "NeedSyntax"},
	{NeedTypesInfo, "NeedTypesInfo"},
	{NeedTypesSizes, "NeedTypesSizes"},
	{NeedForTest, "NeedForTest"},
	{NeedModule, "NeedModule"},
	{NeedEmbedFiles, "NeedEmbedFiles"},
	{NeedEmbedPatterns, "NeedEmbedPatterns"},
	{NeedTarget, "NeedTarget"},
}

func (mode LoadMode) String() string {
	if mode == 0 {
		return "LoadMode(0)"
	}
	var out []string
	// named bits
	for _, item := range modes {
		if (mode & item.mode) != 0 {
			mode ^= item.mode
			out = append(out, item.name)
		}
	}
	// unnamed residue
	if mode != 0 {
		if out == nil {
			return fmt.Sprintf("LoadMode(%#x)", int(mode))
		}
		out = append(out, fmt.Sprintf("%#x", int(mode)))
	}
	if len(out) == 1 {
		return out[0]
	}
	return "(" + strings.Join(out, "|") + ")"
}


================================================
FILE: go/packages/overlay_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages_test

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"reflect"
	"slices"
	"sort"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/packagestest"
	"golang.org/x/tools/internal/testenv"
)

const (
	commonMode = packages.NeedName | packages.NeedFiles |
		packages.NeedCompiledGoFiles | packages.NeedImports | packages.NeedSyntax
	everythingMode = commonMode | packages.NeedDeps | packages.NeedTypes |
		packages.NeedTypesSizes
)

func TestOverlayChangesPackageName(t *testing.T) {
	testAllOrModulesParallel(t, testOverlayChangesPackageName)
}
func testOverlayChangesPackageName(t *testing.T, exporter packagestest.Exporter) {
	log.SetFlags(log.Lshortfile)
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "fake",
		Files: map[string]any{
			"a.go": "package foo\nfunc f(){}\n",
		},
		Overlay: map[string][]byte{
			"a.go": []byte("package foox\nfunc f(){}\n"),
		},
	}})
	defer exported.Cleanup()
	exported.Config.Mode = packages.NeedName

	initial, err := packages.Load(exported.Config,
		filepath.Dir(exported.File("fake", "a.go")))
	if err != nil {
		t.Fatalf("failed to load: %v", err)
	}
	if len(initial) != 1 || initial[0].ID != "fake" || initial[0].Name != "foox" {
		t.Fatalf("got %v, expected [fake]", initial)
	}
	if len(initial[0].Errors) != 0 {
		t.Fatalf("got %v, expected no errors", initial[0].Errors)
	}
	log.SetFlags(0)
}
func TestOverlayChangesBothPackageNames(t *testing.T) {
	testAllOrModulesParallel(t, testOverlayChangesBothPackageNames)
}
func testOverlayChangesBothPackageNames(t *testing.T, exporter packagestest.Exporter) {
	log.SetFlags(log.Lshortfile)
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "fake",
		Files: map[string]any{
			"a.go":      "package foo\nfunc g(){}\n",
			"a_test.go": "package foo\nfunc f(){}\n",
		},
		Overlay: map[string][]byte{
			"a.go":      []byte("package foox\nfunc g(){}\n"),
			"a_test.go": []byte("package foox\nfunc f(){}\n"),
		},
	}})
	defer exported.Cleanup()
	exported.Config.Mode = commonMode

	initial, err := packages.Load(exported.Config,
		filepath.Dir(exported.File("fake", "a.go")))
	if err != nil {
		t.Fatalf("failed to load: %v", err)
	}
	if len(initial) != 3 {
		t.Errorf("got %d packages, expected 3", len(initial))
	}
	want := []struct {
		id, name string
		count    int
	}{
		{"fake", "foox", 1},
		{"fake [fake.test]", "foox", 2},
		{"fake.test", "main", 1},
	}
	if len(initial) != 3 {
		t.Fatalf("expected 3 packages, got %v", len(initial))
	}
	for i := range 3 {
		if ok := checkPkg(t, initial[i], want[i].id, want[i].name, want[i].count); !ok {
			t.Errorf("%d: got {%s %s %d}, expected %v", i, initial[i].ID,
				initial[i].Name, len(initial[i].Syntax), want[i])
		}
		if len(initial[i].Errors) != 0 {
			t.Errorf("%d: got %v, expected no errors", i, initial[i].Errors)
		}
	}
	log.SetFlags(0)
}
func TestOverlayChangesTestPackageName(t *testing.T) {
	testAllOrModulesParallel(t, testOverlayChangesTestPackageName)
}
func testOverlayChangesTestPackageName(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "fake",
		Files: map[string]any{
			"a_test.go": "package foo\nfunc f(){}\n",
		},
		Overlay: map[string][]byte{
			"a_test.go": []byte("package foox\nfunc f(){}\n"),
		},
	}})
	defer exported.Cleanup()
	exported.Config.Mode = commonMode

	initial, err := packages.Load(exported.Config,
		filepath.Dir(exported.File("fake", "a_test.go")))
	if err != nil {
		t.Fatalf("failed to load: %v", err)
	}
	if len(initial) != 3 {
		t.Errorf("got %d packages, expected 3", len(initial))
	}
	want := []struct {
		id, name string
		count    int
	}{
		{"fake", "foox", 0},
		{"fake [fake.test]", "foox", 1},
		{"fake.test", "main", 1},
	}
	if len(initial) != 3 {
		t.Fatalf("expected 3 packages, got %v", len(initial))
	}
	for i := range 3 {
		if ok := checkPkg(t, initial[i], want[i].id, want[i].name, want[i].count); !ok {
			t.Errorf("got {%s %s %d}, expected %v", initial[i].ID,
				initial[i].Name, len(initial[i].Syntax), want[i])
		}
	}
	if len(initial[0].Errors) != 0 {
		t.Fatalf("got %v, expected no errors", initial[0].Errors)
	}
	log.SetFlags(0)
}

func checkPkg(t *testing.T, p *packages.Package, id, name string, syntax int) bool {
	t.Helper()
	if p.ID == id && p.Name == name && len(p.Syntax) == syntax {
		return true
	}
	return false
}

func TestOverlayXTests(t *testing.T) {
	testAllOrModulesParallel(t, testOverlayXTests)
}

// This test checks the behavior of go/packages.Load with an overlaid
// x test. The source of truth is the go/packages.Load results for the
// exact same package, just on-disk.
func testOverlayXTests(t *testing.T, exporter packagestest.Exporter) {
	const aFile = `package a; const C = "C"; func Hello() {}`
	const aTestVariant = `package a

import "testing"

const TestC = "test" + C

func TestHello(){
	Hello()
}`
	const aXTest = `package a_test

import (
	"testing"

	"golang.org/fake/a"
)

const xTestC = "x" + a.C

func TestHello(t *testing.T) {
	a.Hello()
}`

	// First, get the source of truth by loading the package, all on disk.
	onDisk := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":        aFile,
			"a/a_test.go":   aTestVariant,
			"a/a_x_test.go": aXTest,
		},
	}})
	defer onDisk.Cleanup()

	onDisk.Config.Mode = commonMode
	onDisk.Config.Tests = true
	onDisk.Config.Mode = packages.LoadTypes
	initial, err := packages.Load(onDisk.Config, fmt.Sprintf("file=%s", onDisk.File("golang.org/fake", "a/a_x_test.go")))
	if err != nil {
		t.Fatal(err)
	}
	wantPkg := initial[0]

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":        aFile,
			"a/a_test.go":   aTestVariant,
			"a/a_x_test.go": ``, // empty x test on disk
		},
		Overlay: map[string][]byte{
			"a/a_x_test.go": []byte(aXTest),
		},
	}})
	defer exported.Cleanup()

	if len(initial) != 1 {
		t.Fatalf("expected 1 package, got %d", len(initial))
	}
	// Confirm that the overlaid package is identical to the on-disk version.
	pkg := initial[0]
	if !reflect.DeepEqual(wantPkg, pkg) {
		t.Fatalf("mismatched packages: want %#v, got %#v", wantPkg, pkg)
	}
	xTestC := constant(pkg, "xTestC")
	if xTestC == nil {
		t.Fatalf("no value for xTestC")
	}
	got := xTestC.Val().String()
	// TODO(rstambler): Ideally, this test would check that the test variant
	// was imported, but that's pretty complicated.
	if want := `"xC"`; got != want {
		t.Errorf("got: %q, want %q", got, want)
	}
}

func TestOverlay(t *testing.T) { testAllOrModulesParallel(t, testOverlay) }
func testOverlay(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":      `package a; import "golang.org/fake/b"; const A = "a" + b.B`,
			"b/b.go":      `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
			"c/c.go":      `package c; const C = "c"`,
			"c/c_test.go": `package c; import "testing"; func TestC(t *testing.T) {}`,
			"d/d.go":      `package d; const D = "d"`,
		}}})
	defer exported.Cleanup()

	for i, test := range []struct {
		overlay  map[string][]byte
		want     string // expected value of a.A
		wantErrs []string
	}{
		{nil, `"abc"`, nil},                 // default
		{map[string][]byte{}, `"abc"`, nil}, // empty overlay
		{map[string][]byte{exported.File("golang.org/fake", "c/c.go"): []byte(`package c; const C = "C"`)}, `"abC"`, nil},
		{map[string][]byte{exported.File("golang.org/fake", "b/b.go"): []byte(`package b; import "golang.org/fake/c"; const B = "B" + c.C`)}, `"aBc"`, nil},
		// Overlay with an existing file in an existing package adding a new import.
		{map[string][]byte{exported.File("golang.org/fake", "b/b.go"): []byte(`package b; import "golang.org/fake/d"; const B = "B" + d.D`)}, `"aBd"`, nil},
		// Overlay with an existing file in an existing package.
		{map[string][]byte{exported.File("golang.org/fake", "c/c.go"): []byte(`package c; import "net/http"; const C = http.MethodGet`)}, `"abGET"`, nil},
		// Overlay with a new file in an existing package.
		{map[string][]byte{
			exported.File("golang.org/fake", "c/c.go"):                                               []byte(`package c;`),
			filepath.Join(filepath.Dir(exported.File("golang.org/fake", "c/c.go")), "c_new_file.go"): []byte(`package c; const C = "Ç"`)},
			`"abÇ"`, nil},
		// Overlay with a new file in an existing package, adding a new dependency to that package.
		{map[string][]byte{
			exported.File("golang.org/fake", "c/c.go"):                                               []byte(`package c;`),
			filepath.Join(filepath.Dir(exported.File("golang.org/fake", "c/c.go")), "c_new_file.go"): []byte(`package c; import "golang.org/fake/d"; const C = "c" + d.D`)},
			`"abcd"`, nil},
	} {
		exported.Config.Overlay = test.overlay
		exported.Config.Mode = packages.LoadAllSyntax
		initial, err := packages.Load(exported.Config, "golang.org/fake/a")
		if err != nil {
			t.Error(err)
			continue
		}

		// Check value of a.A.
		a := initial[0]
		aA := constant(a, "A")
		if aA == nil {
			t.Errorf("%d. a.A: got nil", i)
			continue
		}
		got := aA.Val().String()
		if got != test.want {
			t.Errorf("%d. a.A: got %s, want %s", i, got, test.want)
		}

		// Check errors.
		var errors []packages.Error
		for pkg := range packages.Postorder(initial) {
			errors = append(errors, pkg.Errors...)
		}
		if errs := errorMessages(errors); !reflect.DeepEqual(errs, test.wantErrs) {
			t.Errorf("%d. got errors %s, want %s", i, errs, test.wantErrs)
		}
	}
}

func TestOverlayDeps(t *testing.T) { testAllOrModulesParallel(t, testOverlayDeps) }
func testOverlayDeps(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"c/c.go":      `package c; const C = "c"`,
			"c/c_test.go": `package c; import "testing"; func TestC(t *testing.T) {}`,
		},
	}})
	defer exported.Cleanup()

	exported.Config.Overlay = map[string][]byte{exported.File("golang.org/fake", "c/c.go"): []byte(`package c; import "net/http"; const C = http.MethodGet`)}
	exported.Config.Mode = packages.NeedName |
		packages.NeedFiles |
		packages.NeedCompiledGoFiles |
		packages.NeedImports |
		packages.NeedDeps |
		packages.NeedTypesSizes
	pkgs, err := packages.Load(exported.Config, fmt.Sprintf("file=%s", exported.File("golang.org/fake", "c/c.go")))
	if err != nil {
		t.Error(err)
	}

	// Find package golang.org/fake/c
	sort.Slice(pkgs, func(i, j int) bool { return pkgs[i].ID < pkgs[j].ID })
	if len(pkgs) != 2 {
		t.Fatalf("expected 2 packages, got %v", len(pkgs))
	}
	pkgc := pkgs[0]
	if pkgc.ID != "golang.org/fake/c" {
		t.Errorf("expected first package in sorted list to be \"golang.org/fake/c\", got %v", pkgc.ID)
	}

	// Make sure golang.org/fake/c imports net/http, as per the overlay.
	contains := func(imports map[string]*packages.Package, wantImport string) bool {
		for imp := range imports {
			if imp == wantImport {
				return true
			}
		}
		return false
	}
	if !contains(pkgc.Imports, "net/http") {
		t.Errorf("expected import of %s in package %s, got the following imports: %v",
			"net/http", pkgc.ID, pkgc.Imports)
	}

}

func TestNewPackagesInOverlay(t *testing.T) { testAllOrModulesParallel(t, testNewPackagesInOverlay) }
func testNewPackagesInOverlay(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"a/a.go": `package a; import "golang.org/fake/b"; const A = "a" + b.B`,
				"b/b.go": `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
				"c/c.go": `package c; const C = "c"`,
				"d/d.go": `package d; const D = "d"`,
			},
		},
		{
			Name: "example.com/extramodule",
			Files: map[string]any{
				"pkg/x.go": "package pkg\n",
			},
		},
	})
	defer exported.Cleanup()

	dir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "a/a.go")))

	for _, test := range []struct {
		name    string
		overlay map[string][]byte
		want    string // expected value of e.E
	}{
		{"one_file",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"): []byte(`package e; import "golang.org/fake/a"; const E = "e" + a.A`)},
			`"eabc"`},
		{"multiple_files_same_package",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"):      []byte(`package e; import "golang.org/fake/a"; const E = "e" + a.A + underscore`),
				filepath.Join(dir, "e", "e_util.go"): []byte(`package e; const underscore = "_"`),
			},
			`"eabc_"`},
		{"multiple_files_two_packages",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"):      []byte(`package e; import "golang.org/fake/f"; const E = "e" + f.F + underscore`),
				filepath.Join(dir, "e", "e_util.go"): []byte(`package e; const underscore = "_"`),
				filepath.Join(dir, "f", "f.go"):      []byte(`package f; const F = "f"`),
			},
			`"ef_"`},
		{"multiple_files_three_packages",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"):      []byte(`package e; import "golang.org/fake/f"; const E = "e" + f.F + underscore`),
				filepath.Join(dir, "e", "e_util.go"): []byte(`package e; const underscore = "_"`),
				filepath.Join(dir, "f", "f.go"):      []byte(`package f; import "golang.org/fake/g"; const F = "f" + g.G`),
				filepath.Join(dir, "g", "g.go"):      []byte(`package g; const G = "g"`),
			},
			`"efg_"`},
		{"multiple_files_four_packages",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"):      []byte(`package e; import "golang.org/fake/f"; import "golang.org/fake/h"; const E = "e" + f.F + h.H + underscore`),
				filepath.Join(dir, "e", "e_util.go"): []byte(`package e; const underscore = "_"`),
				filepath.Join(dir, "f", "f.go"):      []byte(`package f; import "golang.org/fake/g"; const F = "f" + g.G`),
				filepath.Join(dir, "g", "g.go"):      []byte(`package g; const G = "g"`),
				filepath.Join(dir, "h", "h.go"):      []byte(`package h; const H = "h"`),
			},
			`"efgh_"`},
		{"multiple_files_four_packages_again",
			map[string][]byte{
				filepath.Join(dir, "e", "e.go"):      []byte(`package e; import "golang.org/fake/f"; const E = "e" + f.F + underscore`),
				filepath.Join(dir, "e", "e_util.go"): []byte(`package e; const underscore = "_"`),
				filepath.Join(dir, "f", "f.go"):      []byte(`package f; import "golang.org/fake/g"; const F = "f" + g.G`),
				filepath.Join(dir, "g", "g.go"):      []byte(`package g; import "golang.org/fake/h"; const G = "g" + h.H`),
				filepath.Join(dir, "h", "h.go"):      []byte(`package h; const H = "h"`),
			},
			`"efgh_"`},
		{"main_overlay",
			map[string][]byte{
				filepath.Join(dir, "e", "main.go"): []byte(`package main; import "golang.org/fake/a"; const E = "e" + a.A; func main(){}`)},
			`"eabc"`},
	} {
		t.Run(test.name, func(t *testing.T) {
			exported.Config.Overlay = test.overlay
			exported.Config.Mode = packages.LoadAllSyntax
			exported.Config.Logf = t.Logf

			// With an overlay, we don't know the expected import path,
			// so load with the absolute path of the directory.
			initial, err := packages.Load(exported.Config, filepath.Join(dir, "e"))
			if err != nil {
				t.Fatal(err)
			}

			// Check value of e.E.
			e := initial[0]
			eE := constant(e, "E")
			if eE == nil {
				t.Fatalf("e.E: was nil in %#v", e)
			}
			got := eE.Val().String()
			if got != test.want {
				t.Fatalf("e.E: got %s, want %s", got, test.want)
			}
		})
	}
}

// Test that we can create a package and its test package in an overlay.
func TestOverlayNewPackageAndTest(t *testing.T) {
	testAllOrModulesParallel(t, testOverlayNewPackageAndTest)
}
func testOverlayNewPackageAndTest(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"foo.txt": "placeholder",
			},
		},
	})
	defer exported.Cleanup()

	dir := filepath.Dir(exported.File("golang.org/fake", "foo.txt"))
	exported.Config.Overlay = map[string][]byte{
		filepath.Join(dir, "a.go"):      []byte(`package a;`),
		filepath.Join(dir, "a_test.go"): []byte(`package a; import "testing";`),
	}
	initial, err := packages.Load(exported.Config, "file="+filepath.Join(dir, "a.go"), "file="+filepath.Join(dir, "a_test.go"))
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) != 2 {
		t.Errorf("got %v packages, wanted %v", len(initial), 2)
	}
}

func TestAdHocOverlays(t *testing.T) {
	t.Parallel()
	testenv.NeedsTool(t, "go")

	// This test doesn't use packagestest because we are testing ad-hoc packages,
	// which are outside of $GOPATH and outside of a module.
	tmp, err := os.MkdirTemp("", "testAdHocOverlays")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmp)

	filename := filepath.Join(tmp, "a.go")
	content := []byte(`package a
const A = 1
`)

	// Make sure that the user's value of GO111MODULE does not affect test results.
	for _, go111module := range []string{"off", "auto", "on"} {
		t.Run("GO111MODULE="+go111module, func(t *testing.T) {
			config := &packages.Config{
				Dir:  tmp,
				Env:  append(os.Environ(), "GOPACKAGESDRIVER=off", fmt.Sprintf("GO111MODULE=%s", go111module)),
				Mode: packages.LoadAllSyntax,
				Overlay: map[string][]byte{
					filename: content,
				},
				Logf: t.Logf,
			}
			initial, err := packages.Load(config, fmt.Sprintf("file=%s", filename))
			if err != nil {
				t.Fatal(err)
			}
			if len(initial) == 0 {
				t.Fatalf("no packages for %s", filename)
			}
			// Check value of a.A.
			a := initial[0]
			if a.Errors != nil {
				t.Fatalf("a: got errors %+v, want no error", err)
			}
			aA := constant(a, "A")
			if aA == nil {
				t.Errorf("a.A: got nil")
				return
			}
			got := aA.Val().String()
			if want := "1"; got != want {
				t.Errorf("a.A: got %s, want %s", got, want)
			}
		})
	}
}

// TestOverlayModFileChanges tests the behavior resulting from having files
// from multiple modules in overlays.
func TestOverlayModFileChanges(t *testing.T) {
	t.Parallel()
	testenv.NeedsTool(t, "go")

	// Create two unrelated modules in a temporary directory.
	tmp, err := os.MkdirTemp("", "tmp")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmp)

	// mod1 has a dependency on golang.org/x/xerrors.
	mod1, err := os.MkdirTemp(tmp, "mod1")
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(mod1, "go.mod"), []byte(`module mod1

	require (
		golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7
	)
	`), 0775); err != nil {
		t.Fatal(err)
	}

	// mod2 does not have any dependencies.
	mod2, err := os.MkdirTemp(tmp, "mod2")
	if err != nil {
		t.Fatal(err)
	}

	want := `module mod2

go 1.11
`
	if err := os.WriteFile(filepath.Join(mod2, "go.mod"), []byte(want), 0775); err != nil {
		t.Fatal(err)
	}

	// Run packages.Load on mod2, while passing the contents over mod1/main.go in the overlay.
	config := &packages.Config{
		Dir:  mod2,
		Env:  append(os.Environ(), "GOPACKAGESDRIVER=off"),
		Mode: packages.LoadImports,
		Overlay: map[string][]byte{
			filepath.Join(mod1, "main.go"): []byte(`package main
import "golang.org/x/xerrors"
func main() {
	_ = errors.New("")
}
`),
			filepath.Join(mod2, "main.go"): []byte(`package main
func main() {}
`),
		},
	}
	if _, err := packages.Load(config, fmt.Sprintf("file=%s", filepath.Join(mod2, "main.go"))); err != nil {
		t.Fatal(err)
	}

	// Check that mod2/go.mod has not been modified.
	got, err := os.ReadFile(filepath.Join(mod2, "go.mod"))
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != want {
		t.Errorf("expected %s, got %s", want, string(got))
	}
}

func TestOverlayGOPATHVendoring(t *testing.T) {
	t.Parallel()

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"vendor/vendor.com/foo/foo.go": `package foo; const X = "hi"`,
			"user/user.go":                 `package user`,
		},
	}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadAllSyntax
	exported.Config.Logf = t.Logf
	exported.Config.Overlay = map[string][]byte{
		exported.File("golang.org/fake", "user/user.go"): []byte(`package user; import "vendor.com/foo"; var x = foo.X`),
	}
	initial, err := packages.Load(exported.Config, "golang.org/fake/user")
	if err != nil {
		t.Fatal(err)
	}
	user := initial[0]
	if len(user.Imports) != 1 {
		t.Fatal("no imports for user")
	}
	if user.Imports["vendor.com/foo"].Name != "foo" {
		t.Errorf("failed to load vendored package foo, imports: %#v", user.Imports["vendor.com/foo"])
	}
}

func TestContainsOverlay(t *testing.T) { testAllOrModulesParallel(t, testContainsOverlay) }
func testContainsOverlay(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"`,
			"b/b.go": `package b; import "golang.org/fake/c"`,
			"c/c.go": `package c`,
		}}})
	defer exported.Cleanup()
	bOverlayFile := filepath.Join(filepath.Dir(exported.File("golang.org/fake", "b/b.go")), "b_overlay.go")
	exported.Config.Mode = packages.LoadImports
	exported.Config.Overlay = map[string][]byte{bOverlayFile: []byte(`package b;`)}
	initial, err := packages.Load(exported.Config, "file="+bOverlayFile)
	if err != nil {
		t.Fatal(err)
	}

	graph, _ := importGraph(initial)
	wantGraph := `
* golang.org/fake/b
  golang.org/fake/c
  golang.org/fake/b -> golang.org/fake/c
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

func TestContainsOverlayXTest(t *testing.T) { testAllOrModulesParallel(t, testContainsOverlayXTest) }
func testContainsOverlayXTest(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"`,
			"b/b.go": `package b; import "golang.org/fake/c"`,
			"c/c.go": `package c`,
		}}})
	defer exported.Cleanup()

	bOverlayXTestFile := filepath.Join(filepath.Dir(exported.File("golang.org/fake", "b/b.go")), "b_overlay_x_test.go")
	exported.Config.Mode = packages.NeedName | packages.NeedFiles | packages.NeedImports
	exported.Config.Overlay = map[string][]byte{bOverlayXTestFile: []byte(`package b_test; import "golang.org/fake/b"`)}
	initial, err := packages.Load(exported.Config, "file="+bOverlayXTestFile)
	if err != nil {
		t.Fatal(err)
	}

	graph, _ := importGraph(initial)
	wantGraph := `
  golang.org/fake/b
* golang.org/fake/b_test [golang.org/fake/b.test]
  golang.org/fake/c
  golang.org/fake/b -> golang.org/fake/c
  golang.org/fake/b_test [golang.org/fake/b.test] -> golang.org/fake/b
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

func TestInvalidFilesBeforeOverlay(t *testing.T) {
	testAllOrModulesParallel(t, testInvalidFilesBeforeOverlay)
}

func testInvalidFilesBeforeOverlay(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"d/d.go":  ``,
				"main.go": ``,
			},
		},
	})
	defer exported.Cleanup()

	dir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "d/d.go")))

	exported.Config.Mode = everythingMode
	exported.Config.Tests = true

	// First, check that all packages returned have files associated with them.
	// Tests the work-around for golang/go#39986.
	t.Run("no overlay", func(t *testing.T) {
		initial, err := packages.Load(exported.Config, fmt.Sprintf("%s/...", dir))
		if err != nil {
			t.Fatal(err)
		}
		for _, pkg := range initial {
			if len(pkg.CompiledGoFiles) == 0 {
				t.Fatalf("expected at least 1 CompiledGoFile for %s, got none", pkg.PkgPath)
			}
		}
	})

}

// Tests golang/go#35973, fixed in Go 1.14.
func TestInvalidFilesBeforeOverlayContains(t *testing.T) {
	testAllOrModulesParallel(t, testInvalidFilesBeforeOverlayContains)
}
func testInvalidFilesBeforeOverlayContains(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"d/d.go":      `package d; import "net/http"; const Get = http.MethodGet; const Hello = "hello";`,
				"d/util.go":   ``,
				"d/d_test.go": ``,
				"main.go":     ``,
			},
		},
	})
	defer exported.Cleanup()

	dir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "d/d.go")))

	// Additional tests for test variants.
	for i, tt := range []struct {
		name    string
		overlay map[string][]byte
		want    string // expected value of d.D
		wantID  string // expected value for the package ID
	}{
		// Overlay with a test variant.
		{
			"test_variant",
			map[string][]byte{
				filepath.Join(dir, "d", "d_test.go"): []byte(`package d; import "testing"; const D = Get + "_test"; func TestD(t *testing.T) {};`),
			},
			`"GET_test"`, "golang.org/fake/d [golang.org/fake/d.test]",
		},
		// Overlay in package.
		{
			"second_file",
			map[string][]byte{
				filepath.Join(dir, "d", "util.go"): []byte(`package d; const D = Get + "_util";`),
			},
			`"GET_util"`, "golang.org/fake/d",
		},
		// Overlay on the main file.
		{
			"main",
			map[string][]byte{
				filepath.Join(dir, "main.go"): []byte(`package main; import "golang.org/fake/d"; const D = d.Get + "_main"; func main() {};`),
			},
			`"GET_main"`, "golang.org/fake",
		},
		{
			"xtest",
			map[string][]byte{
				filepath.Join(dir, "d", "d_test.go"): []byte(`package d_test; import "golang.org/fake/d"; import "testing"; const D = d.Get + "_xtest"; func TestD(t *testing.T) {};`),
			},
			`"GET_xtest"`, "golang.org/fake/d_test [golang.org/fake/d.test]",
		},
	} {
		t.Run(tt.name, func(t *testing.T) {
			exported.Config.Overlay = tt.overlay
			exported.Config.Mode = everythingMode
			exported.Config.Tests = true

			for f := range tt.overlay {
				initial, err := packages.Load(exported.Config, fmt.Sprintf("file=%s", f))
				if err != nil {
					t.Fatal(err)
				}
				if len(initial) != 1 &&
					(len(initial) != 2 || !isTestVariant(initial[0].ID, initial[1].ID)) {
					t.Fatalf("expected 1 package (perhaps with test variant), got %v", len(initial))
				}
				pkg := initial[0]
				if pkg.ID != tt.wantID {
					t.Fatalf("expected package ID %q, got %q", tt.wantID, pkg.ID)
				}
				var containsFile bool
				if slices.Contains(pkg.CompiledGoFiles, f) {
					containsFile = true
				}
				if !containsFile {
					t.Fatalf("expected %s in CompiledGoFiles, got %v", f, pkg.CompiledGoFiles)
				}
				// Check value of d.D.
				D := constant(pkg, "D")
				if D == nil {
					t.Fatalf("%d. D: got nil", i)
				}
				got := D.Val().String()
				if got != tt.want {
					t.Fatalf("%d. D: got %s, want %s", i, got, tt.want)
				}
			}
		})
	}
}

func isTestVariant(libID, testID string) bool {
	variantID := fmt.Sprintf("%[1]s [%[1]s.test]", libID)
	return variantID == testID
}

func TestInvalidXTestInGOPATH(t *testing.T) {
	testAllOrModulesParallel(t, testInvalidXTestInGOPATH)
}
func testInvalidXTestInGOPATH(t *testing.T, exporter packagestest.Exporter) {
	t.Skip("Not fixed yet. See golang.org/issue/40825.")

	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"x/x.go":      `package x`,
				"x/x_test.go": ``,
			},
		},
	})
	defer exported.Cleanup()

	dir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "x/x.go")))

	exported.Config.Mode = everythingMode
	exported.Config.Tests = true

	initial, err := packages.Load(exported.Config, fmt.Sprintf("%s/...", dir))
	if err != nil {
		t.Fatal(err)
	}
	pkg := initial[0]
	if len(pkg.CompiledGoFiles) != 2 {
		t.Fatalf("expected at least 2 CompiledGoFiles for %s, got %v", pkg.PkgPath, len(pkg.CompiledGoFiles))
	}
}

// Reproduces golang/go#40685.
func TestAddImportInOverlay(t *testing.T) {
	testAllOrModulesParallel(t, testAddImportInOverlay)
}
func testAddImportInOverlay(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"a/a.go": `package a

import (
	"fmt"
)

func _() {
	fmt.Println("")
	os.Stat("")
}`,
				"a/a_test.go": `package a

import (
	"os"
	"testing"
)

func TestA(t *testing.T) {
	os.Stat("")
}`,
			},
		},
	})
	defer exported.Cleanup()

	exported.Config.Mode = everythingMode
	exported.Config.Tests = true

	dir := filepath.Dir(exported.File("golang.org/fake", "a/a.go"))
	exported.Config.Overlay = map[string][]byte{
		filepath.Join(dir, "a.go"): []byte(`package a

import (
	"fmt"
	"os"
)

func _() {
	fmt.Println("")
	os.Stat("")
}
`),
	}
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	pkg := initial[0]
	var foundOs bool
	for _, imp := range pkg.Imports {
		if imp.PkgPath == "os" {
			foundOs = true
			break
		}
	}
	if !foundOs {
		t.Fatalf(`expected import "os", found none: %v`, pkg.Imports)
	}
}

// Tests that overlays are applied for different kinds of load patterns.
func TestLoadDifferentPatterns(t *testing.T) {
	testAllOrModulesParallel(t, testLoadDifferentPatterns)
}
func testLoadDifferentPatterns(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"foo.txt": "placeholder",
				"b/b.go": `package b
import "golang.org/fake/a"
func _() {
	a.Hi()
}
`,
			},
		},
	})
	defer exported.Cleanup()

	exported.Config.Mode = everythingMode
	exported.Config.Tests = true

	dir := filepath.Dir(exported.File("golang.org/fake", "foo.txt"))
	exported.Config.Overlay = map[string][]byte{
		filepath.Join(dir, "a", "a.go"): []byte(`package a
import "fmt"
func Hi() {
	fmt.Println("")
}
`),
	}
	for _, tc := range []struct {
		pattern string
	}{
		{"golang.org/fake/a"},
		{"golang.org/fake/..."},
		{fmt.Sprintf("file=%s", filepath.Join(dir, "a", "a.go"))},
	} {
		t.Run(tc.pattern, func(t *testing.T) {
			initial, err := packages.Load(exported.Config, tc.pattern)
			if err != nil {
				t.Fatal(err)
			}
			var match *packages.Package
			for _, pkg := range initial {
				if pkg.PkgPath == "golang.org/fake/a" {
					match = pkg
					break
				}
			}
			if match == nil {
				t.Fatalf(`expected package path "golang.org/fake/a", got none`)
			}
			if match.PkgPath != "golang.org/fake/a" {
				t.Fatalf(`expected package path "golang.org/fake/a", got %q`, match.PkgPath)
			}
			if _, ok := match.Imports["fmt"]; !ok {
				t.Fatalf(`expected import "fmt", got none`)
			}
		})
	}

	// Now, load "golang.org/fake/b" and confirm that "golang.org/fake/a" is
	// not returned as a root.
	initial, err := packages.Load(exported.Config, "golang.org/fake/b")
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) > 1 {
		t.Fatalf("expected 1 package, got %v", initial)
	}
	pkg := initial[0]
	if pkg.PkgPath != "golang.org/fake/b" {
		t.Fatalf(`expected package path "golang.org/fake/b", got %q`, pkg.PkgPath)
	}
	if _, ok := pkg.Imports["golang.org/fake/a"]; !ok {
		t.Fatalf(`expected import "golang.org/fake/a", got none`)
	}
}

// Tests that overlays are applied for a replaced module.
// This does not use go/packagestest because it needs to write a replace
// directive with an absolute path in one of the module's go.mod files.
func TestOverlaysInReplace(t *testing.T) {
	testenv.NeedsGoPackages(t)
	t.Parallel()

	// Create module b.com in a temporary directory. Do not add any Go files
	// on disk.
	tmpPkgs, err := os.MkdirTemp("", "modules")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpPkgs)

	dirB := filepath.Join(tmpPkgs, "b")
	if err := os.Mkdir(dirB, 0775); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dirB, "go.mod"), fmt.Appendf(nil, "module %s.com", dirB), 0775); err != nil {
		t.Fatal(err)
	}
	if err := os.MkdirAll(filepath.Join(dirB, "inner"), 0775); err != nil {
		t.Fatal(err)
	}

	// Create a separate module that requires and replaces b.com.
	tmpWorkspace, err := os.MkdirTemp("", "workspace")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpWorkspace)
	goModContent := fmt.Sprintf(`module workspace.com

require (
	b.com v0.0.0-00010101000000-000000000000
)

replace (
	b.com => %s
)
`, dirB)
	if err := os.WriteFile(filepath.Join(tmpWorkspace, "go.mod"), []byte(goModContent), 0775); err != nil {
		t.Fatal(err)
	}

	// Add Go files for b.com/inner in an overlay and try loading it from the
	// workspace.com module.
	config := &packages.Config{
		Dir:  tmpWorkspace,
		Mode: packages.LoadAllSyntax,
		Logf: t.Logf,
		Overlay: map[string][]byte{
			filepath.Join(dirB, "inner", "b.go"): []byte(`package inner; import "fmt"; func _() { fmt.Println("");`),
		},
	}
	initial, err := packages.Load(config, "b.com/...")
	if err != nil {
		t.Error(err)
	}
	if len(initial) != 1 {
		t.Fatalf(`expected 1 package, got %v`, len(initial))
	}
	pkg := initial[0]
	if pkg.PkgPath != "b.com/inner" {
		t.Fatalf(`expected package path "b.com/inner", got %q`, pkg.PkgPath)
	}
	if _, ok := pkg.Imports["fmt"]; !ok {
		t.Fatalf(`expected import "fmt", got none`)
	}
}


================================================
FILE: go/packages/packages.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

// See doc.go for package documentation and implementation notes.

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"go/ast"
	"go/parser"
	"go/scanner"
	"go/token"
	"go/types"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/sync/errgroup"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/typesinternal"
)

// A LoadMode controls the amount of detail to return when loading.
// The bits below can be combined to specify which fields should be
// filled in the result packages.
//
// The zero value is a special case, equivalent to combining
// the NeedName, NeedFiles, and NeedCompiledGoFiles bits.
//
// ID and Errors (if present) will always be filled.
// [Load] may return more information than requested.
//
// The Mode flag is a union of several bits named NeedName,
// NeedFiles, and so on, each of which determines whether
// a given field of Package (Name, Files, etc) should be
// populated.
//
// For convenience, we provide named constants for the most
// common combinations of Need flags:
//
//	[LoadFiles]     lists of files in each package
//	[LoadImports]   ... plus imports
//	[LoadTypes]     ... plus type information
//	[LoadSyntax]    ... plus type-annotated syntax
//	[LoadAllSyntax] ... for all dependencies
//
// Unfortunately there are a number of open bugs related to
// interactions among the LoadMode bits:
//   - https://go.dev/issue/56633
//   - https://go.dev/issue/56677
//   - https://go.dev/issue/58726
//   - https://go.dev/issue/63517
type LoadMode int

const (
	// NeedName adds Name and PkgPath.
	NeedName LoadMode = 1 << iota

	// NeedFiles adds Dir, GoFiles, OtherFiles, and IgnoredFiles
	NeedFiles

	// NeedCompiledGoFiles adds CompiledGoFiles.
	NeedCompiledGoFiles

	// NeedImports adds Imports. If NeedDeps is not set, the Imports field will contain
	// "placeholder" Packages with only the ID set.
	NeedImports

	// NeedDeps adds the fields requested by the LoadMode in the packages in Imports.
	NeedDeps

	// NeedExportFile adds ExportFile.
	NeedExportFile

	// NeedTypes adds Types, Fset, and IllTyped.
	NeedTypes

	// NeedSyntax adds Syntax and Fset.
	NeedSyntax

	// NeedTypesInfo adds TypesInfo and Fset.
	NeedTypesInfo

	// NeedTypesSizes adds TypesSizes.
	NeedTypesSizes

	// needInternalDepsErrors adds the internal deps errors field for use by gopls.
	needInternalDepsErrors

	// NeedForTest adds ForTest.
	//
	// Tests must also be set on the context for this field to be populated.
	NeedForTest

	// typecheckCgo enables full support for type checking cgo. Requires Go 1.15+.
	// Modifies CompiledGoFiles and Types, and has no effect on its own.
	typecheckCgo

	// NeedModule adds Module.
	NeedModule

	// NeedEmbedFiles adds EmbedFiles.
	NeedEmbedFiles

	// NeedEmbedPatterns adds EmbedPatterns.
	NeedEmbedPatterns

	// NeedTarget adds Target.
	NeedTarget

	// Be sure to update loadmode_string.go when adding new items!
)

const (
	// LoadFiles loads the name and file names for the initial packages.
	LoadFiles = NeedName | NeedFiles | NeedCompiledGoFiles

	// LoadImports loads the name, file names, and import mapping for the initial packages.
	LoadImports = LoadFiles | NeedImports

	// LoadTypes loads exported type information for the initial packages.
	LoadTypes = LoadImports | NeedTypes | NeedTypesSizes

	// LoadSyntax loads typed syntax for the initial packages.
	LoadSyntax = LoadTypes | NeedSyntax | NeedTypesInfo

	// LoadAllSyntax loads typed syntax for the initial packages and all dependencies.
	LoadAllSyntax = LoadSyntax | NeedDeps

	// Deprecated: NeedExportsFile is a historical misspelling of NeedExportFile.
	//
	//go:fix inline
	NeedExportsFile = NeedExportFile
)

// A Config specifies details about how packages should be loaded.
// The zero value is a valid configuration.
//
// Calls to [Load] do not modify this struct.
type Config struct {
	// Mode controls the level of information returned for each package.
	Mode LoadMode

	// Context specifies the context for the load operation.
	// Cancelling the context may cause [Load] to abort and
	// return an error.
	Context context.Context

	// Logf is the logger for the config.
	// If the user provides a logger, debug logging is enabled.
	// If the GOPACKAGESDEBUG environment variable is set to true,
	// but the logger is nil, default to log.Printf.
	Logf func(format string, args ...any)

	// Dir is the directory in which to run the build system's query tool
	// that provides information about the packages.
	// If Dir is empty, the tool is run in the current directory.
	Dir string

	// Env is the environment to use when invoking the build system's query tool.
	// If Env is nil, the current environment is used.
	// As in os/exec's Cmd, only the last value in the slice for
	// each environment key is used. To specify the setting of only
	// a few variables, append to the current environment, as in:
	//
	//	opt.Env = append(os.Environ(), "GOOS=plan9", "GOARCH=386")
	//
	Env []string

	// BuildFlags is a list of command-line flags to be passed through to
	// the build system's query tool.
	BuildFlags []string

	// Fset provides source position information for syntax trees and types.
	// If Fset is nil, Load will use a new fileset, but preserve Fset's value.
	Fset *token.FileSet

	// ParseFile is called to read and parse each file
	// when preparing a package's type-checked syntax tree.
	// It must be safe to call ParseFile simultaneously from multiple goroutines.
	// If ParseFile is nil, the loader will uses parser.ParseFile.
	//
	// ParseFile should parse the source from src and use filename only for
	// recording position information.
	//
	// An application may supply a custom implementation of ParseFile
	// to change the effective file contents or the behavior of the parser,
	// or to modify the syntax tree. For example, selectively eliminating
	// unwanted function bodies can significantly accelerate type checking.
	ParseFile func(fset *token.FileSet, filename string, src []byte) (*ast.File, error)

	// If Tests is set, the loader includes not just the packages
	// matching a particular pattern but also any related test packages,
	// including test-only variants of the package and the test executable.
	//
	// For example, when using the go command, loading "fmt" with Tests=true
	// returns four packages, with IDs "fmt" (the standard package),
	// "fmt [fmt.test]" (the package as compiled for the test),
	// "fmt_test" (the test functions from source files in package fmt_test),
	// and "fmt.test" (the test binary).
	//
	// In build systems with explicit names for tests,
	// setting Tests may have no effect.
	Tests bool

	// Overlay is a mapping from absolute file paths to file contents.
	//
	// For each map entry, [Load] uses the alternative file
	// contents provided by the overlay mapping instead of reading
	// from the file system. This mechanism can be used to enable
	// editor-integrated tools to correctly analyze the contents
	// of modified but unsaved buffers, for example.
	//
	// The overlay mapping is passed to the build system's driver
	// (see "The driver protocol") so that it too can report
	// consistent package metadata about unsaved files. However,
	// drivers may vary in their level of support for overlays.
	Overlay map[string][]byte
}

// Load loads and returns the Go packages named by the given patterns.
//
// The cfg parameter specifies loading options; nil behaves the same as an empty [Config].
//
// The [Config.Mode] field is a set of bits that determine what kinds
// of information should be computed and returned. Modes that require
// more information tend to be slower. See [LoadMode] for details
// and important caveats. Its zero value is equivalent to
// [NeedName] | [NeedFiles] | [NeedCompiledGoFiles].
//
// Each call to Load returns a new set of [Package] instances.
// The Packages and their Imports form a directed acyclic graph.
//
// If the [NeedTypes] mode flag was set, each call to Load uses a new
// [types.Importer], so [types.Object] and [types.Type] values from
// different calls to Load must not be mixed as they will have
// inconsistent notions of type identity.
//
// If any of the patterns was invalid as defined by the
// underlying build system, Load returns an error.
// It may return an empty list of packages without an error,
// for instance for an empty expansion of a valid wildcard.
// Errors associated with a particular package are recorded in the
// corresponding Package's Errors list, and do not cause Load to
// return an error. Clients may need to handle such errors before
// proceeding with further analysis. The [PrintErrors] function is
// provided for convenient display of all errors.
func Load(cfg *Config, patterns ...string) ([]*Package, error) {
	ld := newLoader(cfg)
	response, external, err := defaultDriver(&ld.Config, patterns...)
	if err != nil {
		return nil, err
	}

	ld.sizes = types.SizesFor(response.Compiler, response.Arch)
	if ld.sizes == nil && ld.Config.Mode&(NeedTypes|NeedTypesSizes|NeedTypesInfo) != 0 {
		// Type size information is needed but unavailable.
		if external {
			// An external driver may fail to populate the Compiler/GOARCH fields,
			// especially since they are relatively new (see #63700).
			// Provide a sensible fallback in this case.
			ld.sizes = types.SizesFor("gc", runtime.GOARCH)
			if ld.sizes == nil { // gccgo-only arch
				ld.sizes = types.SizesFor("gc", "amd64")
			}
		} else {
			// Go list should never fail to deliver accurate size information.
			// Reject the whole Load since the error is the same for every package.
			return nil, fmt.Errorf("can't determine type sizes for compiler %q on GOARCH %q",
				response.Compiler, response.Arch)
		}
	}

	ld.externalDriver = external

	return ld.refine(response)
}

// defaultDriver is a driver that implements go/packages' fallback behavior.
// It will try to request to an external driver, if one exists. If there's
// no external driver, or the driver returns a response with NotHandled set,
// defaultDriver will fall back to the go list driver.
// The boolean result indicates that an external driver handled the request.
func defaultDriver(cfg *Config, patterns ...string) (*DriverResponse, bool, error) {
	const (
		// windowsArgMax specifies the maximum command line length for
		// the Windows' CreateProcess function.
		windowsArgMax = 32767
		// maxEnvSize is a very rough estimation of the maximum environment
		// size of a user.
		maxEnvSize = 16384
		// safeArgMax specifies the maximum safe command line length to use
		// by the underlying driver excl. the environment. We choose the Windows'
		// ARG_MAX as the starting point because it's one of the lowest ARG_MAX
		// constants out of the different supported platforms,
		// e.g., https://www.in-ulm.de/~mascheck/various/argmax/#results.
		safeArgMax = windowsArgMax - maxEnvSize
	)
	chunks, err := splitIntoChunks(patterns, safeArgMax)
	if err != nil {
		return nil, false, err
	}

	if driver := findExternalDriver(cfg); driver != nil {
		response, err := callDriverOnChunks(driver, cfg, chunks)
		if err != nil {
			return nil, false, err
		} else if !response.NotHandled {
			return response, true, nil
		}
		// not handled: fall through
	}

	// go list fallback

	// Write overlays once, as there are many calls
	// to 'go list' (one per chunk plus others too).
	overlayFile, cleanupOverlay, err := gocommand.WriteOverlays(cfg.Overlay)
	if err != nil {
		return nil, false, err
	}
	defer cleanupOverlay()

	var runner gocommand.Runner // (shared across many 'go list' calls)
	driver := func(cfg *Config, patterns []string) (*DriverResponse, error) {
		return goListDriver(cfg, &runner, overlayFile, patterns)
	}
	response, err := callDriverOnChunks(driver, cfg, chunks)
	if err != nil {
		return nil, false, err
	}
	return response, false, err
}

// splitIntoChunks chunks the slice so that the total number of characters
// in a chunk is no longer than argMax.
func splitIntoChunks(patterns []string, argMax int) ([][]string, error) {
	if argMax <= 0 {
		return nil, errors.New("failed to split patterns into chunks, negative safe argMax value")
	}
	var chunks [][]string
	charsInChunk := 0
	nextChunkStart := 0
	for i, v := range patterns {
		vChars := len(v)
		if vChars > argMax {
			// a single pattern is longer than the maximum safe ARG_MAX, hardly should happen
			return nil, errors.New("failed to split patterns into chunks, a pattern is too long")
		}
		charsInChunk += vChars + 1 // +1 is for a whitespace between patterns that has to be counted too
		if charsInChunk > argMax {
			chunks = append(chunks, patterns[nextChunkStart:i])
			nextChunkStart = i
			charsInChunk = vChars
		}
	}
	// add the last chunk
	if nextChunkStart < len(patterns) {
		chunks = append(chunks, patterns[nextChunkStart:])
	}
	return chunks, nil
}

func callDriverOnChunks(driver driver, cfg *Config, chunks [][]string) (*DriverResponse, error) {
	if len(chunks) == 0 {
		return driver(cfg, nil)
	}
	responses := make([]*DriverResponse, len(chunks))
	errNotHandled := errors.New("driver returned NotHandled")
	var g errgroup.Group
	for i, chunk := range chunks {
		g.Go(func() (err error) {
			responses[i], err = driver(cfg, chunk)
			if responses[i] != nil && responses[i].NotHandled {
				err = errNotHandled
			}
			return err
		})
	}
	if err := g.Wait(); err != nil {
		if errors.Is(err, errNotHandled) {
			return &DriverResponse{NotHandled: true}, nil
		}
		return nil, err
	}
	return mergeResponses(responses...), nil
}

func mergeResponses(responses ...*DriverResponse) *DriverResponse {
	if len(responses) == 0 {
		return nil
	}
	// No dedup needed
	if len(responses) == 1 {
		return responses[0]
	}
	response := newDeduper()
	response.dr.NotHandled = false
	response.dr.Compiler = responses[0].Compiler
	response.dr.Arch = responses[0].Arch
	response.dr.GoVersion = responses[0].GoVersion
	for _, v := range responses {
		response.addAll(v)
	}
	return response.dr
}

// A Package describes a loaded Go package.
//
// It also defines part of the JSON schema of [DriverResponse].
// See the package documentation for an overview.
type Package struct {
	// ID is a unique identifier for a package,
	// in a syntax provided by the underlying build system.
	//
	// Because the syntax varies based on the build system,
	// clients should treat IDs as opaque and not attempt to
	// interpret them.
	ID string

	// Name is the package name as it appears in the package source code.
	Name string

	// PkgPath is the package path as used by the go/types package.
	PkgPath string

	// Dir is the directory associated with the package, if it exists.
	//
	// For packages listed by the go command, this is the directory containing
	// the package files.
	Dir string

	// Errors contains any errors encountered querying the metadata
	// of the package, or while parsing or type-checking its files.
	Errors []Error

	// TypeErrors contains the subset of errors produced during type checking.
	TypeErrors []types.Error

	// GoFiles lists the absolute file paths of the package's Go source files.
	// It may include files that should not be compiled, for example because
	// they contain non-matching build tags, are documentary pseudo-files such as
	// unsafe/unsafe.go or builtin/builtin.go, or are subject to cgo preprocessing.
	GoFiles []string

	// CompiledGoFiles lists the absolute file paths of the package's source
	// files that are suitable for type checking.
	// This may differ from GoFiles if files are processed before compilation.
	CompiledGoFiles []string

	// OtherFiles lists the absolute file paths of the package's non-Go source files,
	// including assembly, C, C++, Fortran, Objective-C, SWIG, and so on.
	OtherFiles []string

	// EmbedFiles lists the absolute file paths of the package's files
	// embedded with go:embed.
	EmbedFiles []string

	// EmbedPatterns lists the absolute file patterns of the package's
	// files embedded with go:embed.
	EmbedPatterns []string

	// IgnoredFiles lists source files that are not part of the package
	// using the current build configuration but that might be part of
	// the package using other build configurations.
	IgnoredFiles []string

	// ExportFile is the absolute path to a file containing type
	// information for the package as provided by the build system.
	ExportFile string

	// Target is the absolute install path of the .a file, for libraries,
	// and of the executable file, for binaries.
	Target string

	// Imports maps import paths appearing in the package's Go source files
	// to corresponding loaded Packages.
	Imports map[string]*Package

	// Module is the module information for the package if it exists.
	//
	// Note: it may be missing for std and cmd; see Go issue #65816.
	Module *Module

	// -- The following fields are not part of the driver JSON schema. --

	// Types provides type information for the package.
	// The NeedTypes LoadMode bit sets this field for packages matching the
	// patterns; type information for dependencies may be missing or incomplete,
	// unless NeedDeps and NeedImports are also set.
	//
	// Each call to [Load] returns a consistent set of type
	// symbols, as defined by the comment at [types.Identical].
	// Avoid mixing type information from two or more calls to [Load].
	Types *types.Package `json:"-"`

	// Fset provides position information for Types, TypesInfo, and Syntax.
	// It is set only when Types is set.
	Fset *token.FileSet `json:"-"`

	// IllTyped indicates whether the package or any dependency contains errors.
	// It is set only when Types is set.
	IllTyped bool `json:"-"`

	// Syntax is the package's syntax trees, for the files listed in CompiledGoFiles.
	//
	// The NeedSyntax LoadMode bit populates this field for packages matching the patterns.
	// If NeedDeps and NeedImports are also set, this field will also be populated
	// for dependencies.
	//
	// Syntax is kept in the same order as CompiledGoFiles, with the caveat that nils are
	// removed.  If parsing returned nil, Syntax may be shorter than CompiledGoFiles.
	Syntax []*ast.File `json:"-"`

	// TypesInfo provides type information about the package's syntax trees.
	// It is set only when Syntax is set.
	TypesInfo *types.Info `json:"-"`

	// TypesSizes provides the effective size function for types in TypesInfo.
	TypesSizes types.Sizes `json:"-"`

	// -- internal --

	// ForTest is the package under test, if any.
	ForTest string

	// depsErrors is the DepsErrors field from the go list response, if any.
	depsErrors []*packagesinternal.PackageError
}

// Module provides module information for a package.
//
// It also defines part of the JSON schema of [DriverResponse].
// See the package documentation for an overview.
type Module struct {
	Path      string       // module path
	Version   string       // module version
	Replace   *Module      // replaced by this module
	Time      *time.Time   // time version was created
	Main      bool         // is this the main module?
	Indirect  bool         // is this module only an indirect dependency of main module?
	Dir       string       // directory holding files for this module, if any
	GoMod     string       // path to go.mod file used when loading this module, if any
	GoVersion string       // go version used in module
	Error     *ModuleError // error loading module
}

// ModuleError holds errors loading a module.
type ModuleError struct {
	Err string // the error itself
}

func init() {
	packagesinternal.GetDepsErrors = func(p any) []*packagesinternal.PackageError {
		return p.(*Package).depsErrors
	}
	packagesinternal.TypecheckCgo = int(typecheckCgo)
	packagesinternal.DepsErrors = int(needInternalDepsErrors)
}

// An Error describes a problem with a package's metadata, syntax, or types.
type Error struct {
	Pos  string // "file:line:col" or "file:line" or "" or "-"
	Msg  string
	Kind ErrorKind
}

// ErrorKind describes the source of the error, allowing the user to
// differentiate between errors generated by the driver, the parser, or the
// type-checker.
type ErrorKind int

const (
	UnknownError ErrorKind = iota
	ListError
	ParseError
	TypeError
)

func (err Error) Error() string {
	pos := err.Pos
	if pos == "" {
		pos = "-" // like token.Position{}.String()
	}
	return pos + ": " + err.Msg
}

// flatPackage is the JSON form of Package
// It drops all the type and syntax fields, and transforms the Imports
//
// TODO(adonovan): identify this struct with Package, effectively
// publishing the JSON protocol.
type flatPackage struct {
	ID              string
	Name            string            `json:",omitempty"`
	PkgPath         string            `json:",omitempty"`
	Errors          []Error           `json:",omitempty"`
	GoFiles         []string          `json:",omitempty"`
	CompiledGoFiles []string          `json:",omitempty"`
	OtherFiles      []string          `json:",omitempty"`
	EmbedFiles      []string          `json:",omitempty"`
	EmbedPatterns   []string          `json:",omitempty"`
	IgnoredFiles    []string          `json:",omitempty"`
	ExportFile      string            `json:",omitempty"`
	Imports         map[string]string `json:",omitempty"`
}

// MarshalJSON returns the Package in its JSON form.
// For the most part, the structure fields are written out unmodified, and
// the type and syntax fields are skipped.
// The imports are written out as just a map of path to package id.
// The errors are written using a custom type that tries to preserve the
// structure of error types we know about.
//
// This method exists to enable support for additional build systems.  It is
// not intended for use by clients of the API and we may change the format.
func (p *Package) MarshalJSON() ([]byte, error) {
	flat := &flatPackage{
		ID:              p.ID,
		Name:            p.Name,
		PkgPath:         p.PkgPath,
		Errors:          p.Errors,
		GoFiles:         p.GoFiles,
		CompiledGoFiles: p.CompiledGoFiles,
		OtherFiles:      p.OtherFiles,
		EmbedFiles:      p.EmbedFiles,
		EmbedPatterns:   p.EmbedPatterns,
		IgnoredFiles:    p.IgnoredFiles,
		ExportFile:      p.ExportFile,
	}
	if len(p.Imports) > 0 {
		flat.Imports = make(map[string]string, len(p.Imports))
		for path, ipkg := range p.Imports {
			flat.Imports[path] = ipkg.ID
		}
	}
	return json.Marshal(flat)
}

// UnmarshalJSON reads in a Package from its JSON format.
// See MarshalJSON for details about the format accepted.
func (p *Package) UnmarshalJSON(b []byte) error {
	flat := &flatPackage{}
	if err := json.Unmarshal(b, &flat); err != nil {
		return err
	}
	*p = Package{
		ID:              flat.ID,
		Name:            flat.Name,
		PkgPath:         flat.PkgPath,
		Errors:          flat.Errors,
		GoFiles:         flat.GoFiles,
		CompiledGoFiles: flat.CompiledGoFiles,
		OtherFiles:      flat.OtherFiles,
		EmbedFiles:      flat.EmbedFiles,
		EmbedPatterns:   flat.EmbedPatterns,
		IgnoredFiles:    flat.IgnoredFiles,
		ExportFile:      flat.ExportFile,
	}
	if len(flat.Imports) > 0 {
		p.Imports = make(map[string]*Package, len(flat.Imports))
		for path, id := range flat.Imports {
			p.Imports[path] = &Package{ID: id}
		}
	}
	return nil
}

func (p *Package) String() string { return p.ID }

// loaderPackage augments Package with state used during the loading phase
type loaderPackage struct {
	*Package
	importErrors    map[string]error // maps each bad import to its error
	preds           []*loaderPackage // packages that import this one
	unfinishedSuccs atomic.Int32     // number of direct imports not yet loaded
	color           uint8            // for cycle detection
	needsrc         bool             // load from source (Mode >= LoadTypes)
	needtypes       bool             // type information is either requested or depended on
	initial         bool             // package was matched by a pattern
	goVersion       int              // minor version number of go command on PATH
}

// loader holds the working state of a single call to load.
type loader struct {
	pkgs map[string]*loaderPackage // keyed by Package.ID
	Config
	sizes          types.Sizes // non-nil if needed by mode
	parseCache     map[string]*parseValue
	parseCacheMu   sync.Mutex
	exportMu       sync.Mutex // enforces mutual exclusion of exportdata operations
	externalDriver bool       // true if an external GOPACKAGESDRIVER handled the request

	// Config.Mode contains the implied mode (see impliedLoadMode).
	// Implied mode contains all the fields we need the data for.
	// In requestedMode there are the actually requested fields.
	// We'll zero them out before returning packages to the user.
	// This makes it easier for us to get the conditions where
	// we need certain modes right.
	requestedMode LoadMode
}

type parseValue struct {
	f     *ast.File
	err   error
	ready chan struct{}
}

func newLoader(cfg *Config) *loader {
	ld := &loader{
		parseCache: map[string]*parseValue{},
	}
	if cfg != nil {
		ld.Config = *cfg
		// If the user has provided a logger, use it.
		ld.Config.Logf = cfg.Logf
	}
	if ld.Config.Logf == nil {
		// If the GOPACKAGESDEBUG environment variable is set to true,
		// but the user has not provided a logger, default to log.Printf.
		if debug {
			ld.Config.Logf = log.Printf
		} else {
			ld.Config.Logf = func(format string, args ...any) {}
		}
	}
	if ld.Config.Mode == 0 {
		ld.Config.Mode = NeedName | NeedFiles | NeedCompiledGoFiles // Preserve zero behavior of Mode for backwards compatibility.
	}
	if ld.Config.Env == nil {
		ld.Config.Env = os.Environ()
	}
	if ld.Context == nil {
		ld.Context = context.Background()
	}
	if ld.Dir == "" {
		if dir, err := os.Getwd(); err == nil {
			ld.Dir = dir
		}
	}

	// Save the actually requested fields. We'll zero them out before returning packages to the user.
	ld.requestedMode = ld.Mode
	ld.Mode = impliedLoadMode(ld.Mode)

	if ld.Mode&(NeedSyntax|NeedTypes|NeedTypesInfo) != 0 {
		if ld.Fset == nil {
			ld.Fset = token.NewFileSet()
		}

		// ParseFile is required even in LoadTypes mode
		// because we load source if export data is missing.
		if ld.ParseFile == nil {
			ld.ParseFile = func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
				// We implicitly promise to keep doing ast.Object resolution. :(
				const mode = parser.AllErrors | parser.ParseComments
				return parser.ParseFile(fset, filename, src, mode)
			}
		}
	}

	return ld
}

// refine connects the supplied packages into a graph and then adds type
// and syntax information as requested by the LoadMode.
func (ld *loader) refine(response *DriverResponse) ([]*Package, error) {
	roots := response.Roots
	rootMap := make(map[string]int, len(roots))
	for i, root := range roots {
		rootMap[root] = i
	}
	ld.pkgs = make(map[string]*loaderPackage)
	// first pass, fixup and build the map and roots
	var initial = make([]*loaderPackage, len(roots))
	for _, pkg := range response.Packages {
		rootIndex := -1
		if i, found := rootMap[pkg.ID]; found {
			rootIndex = i
		}

		// Overlays can invalidate export data.
		// TODO(matloob): make this check fine-grained based on dependencies on overlaid files
		exportDataInvalid := len(ld.Overlay) > 0 || pkg.ExportFile == "" && pkg.PkgPath != "unsafe"
		// This package needs type information if the caller requested types and the package is
		// either a root, or it's a non-root and the user requested dependencies ...
		needtypes := (ld.Mode&(NeedTypes|NeedTypesInfo) != 0 && (rootIndex >= 0 || ld.Mode&NeedDeps != 0))
		// This package needs source if the call requested source (or types info, which implies source)
		// and the package is either a root, or itas a non- root and the user requested dependencies...
		needsrc := ((ld.Mode&(NeedSyntax|NeedTypesInfo) != 0 && (rootIndex >= 0 || ld.Mode&NeedDeps != 0)) ||
			// ... or if we need types and the exportData is invalid. We fall back to (incompletely)
			// typechecking packages from source if they fail to compile.
			(ld.Mode&(NeedTypes|NeedTypesInfo) != 0 && exportDataInvalid)) && pkg.PkgPath != "unsafe"
		lpkg := &loaderPackage{
			Package:   pkg,
			needtypes: needtypes,
			needsrc:   needsrc,
			goVersion: response.GoVersion,
		}
		ld.pkgs[lpkg.ID] = lpkg
		if rootIndex >= 0 {
			initial[rootIndex] = lpkg
			lpkg.initial = true
		}
	}
	for i, root := range roots {
		if initial[i] == nil {
			return nil, fmt.Errorf("root package %v is missing", root)
		}
	}

	// Materialize the import graph if it is needed (NeedImports),
	// or if we'll be using loadPackages (Need{Syntax|Types|TypesInfo}).
	var leaves []*loaderPackage // packages with no unfinished successors
	if ld.Mode&(NeedImports|NeedSyntax|NeedTypes|NeedTypesInfo) != 0 {
		const (
			white = 0 // new
			grey  = 1 // in progress
			black = 2 // complete
		)

		// visit traverses the import graph, depth-first,
		// and materializes the graph as Packages.Imports.
		//
		// Valid imports are saved in the Packages.Import map.
		// Invalid imports (cycles and missing nodes) are saved in the importErrors map.
		// Thus, even in the presence of both kinds of errors,
		// the Import graph remains a DAG.
		//
		// visit returns whether the package needs src or has a transitive
		// dependency on a package that does. These are the only packages
		// for which we load source code.
		var stack []*loaderPackage
		var visit func(from, lpkg *loaderPackage) bool
		visit = func(from, lpkg *loaderPackage) bool {
			if lpkg.color == grey {
				panic("internal error: grey node")
			}
			if lpkg.color == white {
				lpkg.color = grey
				stack = append(stack, lpkg) // push
				stubs := lpkg.Imports       // the structure form has only stubs with the ID in the Imports
				lpkg.Imports = make(map[string]*Package, len(stubs))
				for importPath, ipkg := range stubs {
					var importErr error
					imp := ld.pkgs[ipkg.ID]
					if imp == nil {
						// (includes package "C" when DisableCgo)
						importErr = fmt.Errorf("missing package: %q", ipkg.ID)
					} else if imp.color == grey {
						importErr = fmt.Errorf("import cycle: %s", stack)
					}
					if importErr != nil {
						if lpkg.importErrors == nil {
							lpkg.importErrors = make(map[string]error)
						}
						lpkg.importErrors[importPath] = importErr
						continue
					}

					if visit(lpkg, imp) {
						lpkg.needsrc = true
					}
					lpkg.Imports[importPath] = imp.Package
				}

				// -- postorder --

				// Complete type information is required for the
				// immediate dependencies of each source package.
				if lpkg.needsrc && ld.Mode&NeedTypes != 0 {
					for _, ipkg := range lpkg.Imports {
						ld.pkgs[ipkg.ID].needtypes = true
					}
				}

				// NeedTypeSizes causes TypeSizes to be set even
				// on packages for which types aren't needed.
				if ld.Mode&NeedTypesSizes != 0 {
					lpkg.TypesSizes = ld.sizes
				}

				// Add packages with no imports directly to the queue of leaves.
				if len(lpkg.Imports) == 0 {
					leaves = append(leaves, lpkg)
				}

				stack = stack[:len(stack)-1] // pop
				lpkg.color = black
			}

			// Add edge from predecessor.
			if from != nil {
				from.unfinishedSuccs.Add(+1) // incref
				lpkg.preds = append(lpkg.preds, from)
			}

			return lpkg.needsrc
		}

		// For each initial package, create its import DAG.
		for _, lpkg := range initial {
			visit(nil, lpkg)
		}

	} else {
		// !NeedImports: drop the stub (ID-only) import packages
		// that we are not even going to try to resolve.
		for _, lpkg := range initial {
			lpkg.Imports = nil
		}
	}

	// Load type data and syntax if needed, starting at
	// the initial packages (roots of the import DAG).
	if ld.Mode&(NeedSyntax|NeedTypes|NeedTypesInfo) != 0 {

		// We avoid using g.SetLimit to limit concurrency as
		// it makes g.Go stop accepting work, which prevents
		// workers from enqeuing, and thus finishing, and thus
		// allowing the group to make progress: deadlock.
		//
		// Instead we use the ioLimit and cpuLimit semaphores.
		g, _ := errgroup.WithContext(ld.Context)

		// enqueues adds a package to the type-checking queue.
		// It must have no unfinished successors.
		var enqueue func(*loaderPackage)
		enqueue = func(lpkg *loaderPackage) {
			g.Go(func() error {
				// Parse and type-check.
				ld.loadPackage(lpkg)

				// Notify each waiting predecessor,
				// and enqueue it when it becomes a leaf.
				for _, pred := range lpkg.preds {
					if pred.unfinishedSuccs.Add(-1) == 0 { // decref
						enqueue(pred)
					}
				}

				return nil
			})
		}

		// Load leaves first, adding new packages
		// to the queue as they become leaves.
		for _, leaf := range leaves {
			enqueue(leaf)
		}

		if err := g.Wait(); err != nil {
			return nil, err // cancelled
		}
	}

	// If the context is done, return its error and
	// throw out [likely] incomplete packages.
	if err := ld.Context.Err(); err != nil {
		return nil, err
	}

	result := make([]*Package, len(initial))
	for i, lpkg := range initial {
		result[i] = lpkg.Package
	}
	for i := range ld.pkgs {
		// Clear all unrequested fields,
		// to catch programs that use more than they request.
		if ld.requestedMode&NeedName == 0 {
			ld.pkgs[i].Name = ""
			ld.pkgs[i].PkgPath = ""
		}
		if ld.requestedMode&NeedFiles == 0 {
			ld.pkgs[i].GoFiles = nil
			ld.pkgs[i].OtherFiles = nil
			ld.pkgs[i].IgnoredFiles = nil
		}
		if ld.requestedMode&NeedEmbedFiles == 0 {
			ld.pkgs[i].EmbedFiles = nil
		}
		if ld.requestedMode&NeedEmbedPatterns == 0 {
			ld.pkgs[i].EmbedPatterns = nil
		}
		if ld.requestedMode&NeedCompiledGoFiles == 0 {
			ld.pkgs[i].CompiledGoFiles = nil
		}
		if ld.requestedMode&NeedImports == 0 {
			ld.pkgs[i].Imports = nil
		}
		if ld.requestedMode&NeedExportFile == 0 {
			ld.pkgs[i].ExportFile = ""
		}
		if ld.requestedMode&NeedTypes == 0 {
			ld.pkgs[i].Types = nil
			ld.pkgs[i].IllTyped = false
		}
		if ld.requestedMode&NeedSyntax == 0 {
			ld.pkgs[i].Syntax = nil
		}
		if ld.requestedMode&(NeedSyntax|NeedTypes|NeedTypesInfo) == 0 {
			ld.pkgs[i].Fset = nil
		}
		if ld.requestedMode&NeedTypesInfo == 0 {
			ld.pkgs[i].TypesInfo = nil
		}
		if ld.requestedMode&NeedTypesSizes == 0 {
			ld.pkgs[i].TypesSizes = nil
		}
		if ld.requestedMode&NeedModule == 0 {
			ld.pkgs[i].Module = nil
		}
	}

	return result, nil
}

// loadPackage loads/parses/typechecks the specified package.
// It must be called only once per Package,
// after immediate dependencies are loaded.
// Precondition: ld.Mode&(NeedSyntax|NeedTypes|NeedTypesInfo) != 0.
func (ld *loader) loadPackage(lpkg *loaderPackage) {
	if lpkg.PkgPath == "unsafe" {
		// To avoid surprises, fill in the blanks consistent
		// with other packages. (For example, some analyzers
		// assert that each needed types.Info map is non-nil
		// even when there is no syntax that would cause them
		// to consult the map.)
		lpkg.Types = types.Unsafe
		lpkg.Fset = ld.Fset
		lpkg.Syntax = []*ast.File{}
		lpkg.TypesInfo = ld.newTypesInfo()
		lpkg.TypesSizes = ld.sizes
		return
	}

	// Call NewPackage directly with explicit name.
	// This avoids skew between golist and go/types when the files'
	// package declarations are inconsistent.
	lpkg.Types = types.NewPackage(lpkg.PkgPath, lpkg.Name)
	lpkg.Fset = ld.Fset

	// Start shutting down if the context is done and do not load
	// source or export data files.
	// Packages that import this one will have ld.Context.Err() != nil.
	// ld.Context.Err() will be returned later by refine.
	if ld.Context.Err() != nil {
		return
	}

	// Subtle: we populate all Types fields with an empty Package
	// before loading export data so that export data processing
	// never has to create a types.Package for an indirect dependency,
	// which would then require that such created packages be explicitly
	// inserted back into the Import graph as a final step after export data loading.
	// (Hence this return is after the Types assignment.)
	// The Diamond test exercises this case.
	if !lpkg.needtypes && !lpkg.needsrc {
		return
	}

	// TODO(adonovan): this condition looks wrong:
	// I think it should be lpkg.needtypes && !lpg.needsrc,
	// so that NeedSyntax without NeedTypes can be satisfied by export data.
	if !lpkg.needsrc {
		if err := ld.loadFromExportData(lpkg); err != nil {
			lpkg.Errors = append(lpkg.Errors, Error{
				Pos:  "-",
				Msg:  err.Error(),
				Kind: UnknownError, // e.g. can't find/open/parse export data
			})
		}
		return // not a source package, don't get syntax trees
	}

	appendError := func(err error) {
		// Convert various error types into the one true Error.
		var errs []Error
		switch err := err.(type) {
		case Error:
			// from driver
			errs = append(errs, err)

		case *os.PathError:
			// from parser
			errs = append(errs, Error{
				Pos:  err.Path + ":1",
				Msg:  err.Err.Error(),
				Kind: ParseError,
			})

		case scanner.ErrorList:
			// from parser
			for _, err := range err {
				errs = append(errs, Error{
					Pos:  err.Pos.String(),
					Msg:  err.Msg,
					Kind: ParseError,
				})
			}

		case types.Error:
			// from type checker
			lpkg.TypeErrors = append(lpkg.TypeErrors, err)
			errs = append(errs, Error{
				Pos:  err.Fset.Position(err.Pos).String(),
				Msg:  err.Msg,
				Kind: TypeError,
			})

		default:
			// unexpected impoverished error from parser?
			errs = append(errs, Error{
				Pos:  "-",
				Msg:  err.Error(),
				Kind: UnknownError,
			})

			// If you see this error message, please file a bug.
			log.Printf("internal error: error %q (%T) without position", err, err)
		}

		lpkg.Errors = append(lpkg.Errors, errs...)
	}

	// If the go command on the PATH is newer than the runtime,
	// then the go/{scanner,ast,parser,types} packages from the
	// standard library may be unable to process the files
	// selected by go list.
	//
	// There is currently no way to downgrade the effective
	// version of the go command (see issue 52078), so we proceed
	// with the newer go command but, in case of parse or type
	// errors, we emit an additional diagnostic.
	//
	// See:
	// - golang.org/issue/52078 (flag to set release tags)
	// - golang.org/issue/50825 (gopls legacy version support)
	// - golang.org/issue/55883 (go/packages confusing error)
	//
	// Should we assert a hard minimum of (currently) go1.16 here?
	var runtimeVersion int
	if _, err := fmt.Sscanf(runtime.Version(), "go1.%d", &runtimeVersion); err == nil && runtimeVersion < lpkg.goVersion {
		defer func() {
			if len(lpkg.Errors) > 0 {
				appendError(Error{
					Pos:  "-",
					Msg:  fmt.Sprintf("This application uses version go1.%d of the source-processing packages but runs version go1.%d of 'go list'. It may fail to process source files that rely on newer language features. If so, rebuild the application using a newer version of Go.", runtimeVersion, lpkg.goVersion),
					Kind: UnknownError,
				})
			}
		}()
	}

	if ld.Config.Mode&NeedTypes != 0 && len(lpkg.CompiledGoFiles) == 0 && lpkg.ExportFile != "" {
		// The config requested loading sources and types, but sources are missing.
		// Add an error to the package and fall back to loading from export data.
		appendError(Error{"-", fmt.Sprintf("sources missing for package %s", lpkg.ID), ParseError})
		_ = ld.loadFromExportData(lpkg) // ignore any secondary errors

		return // can't get syntax trees for this package
	}

	files, errs := ld.parseFiles(lpkg.CompiledGoFiles)
	for _, err := range errs {
		appendError(err)
	}

	lpkg.Syntax = files
	if ld.Config.Mode&(NeedTypes|NeedTypesInfo) == 0 {
		return
	}

	// Start shutting down if the context is done and do not type check.
	// Packages that import this one will have ld.Context.Err() != nil.
	// ld.Context.Err() will be returned later by refine.
	if ld.Context.Err() != nil {
		return
	}

	lpkg.TypesInfo = ld.newTypesInfo()
	lpkg.TypesSizes = ld.sizes

	importer := importerFunc(func(path string) (*types.Package, error) {
		if path == "unsafe" {
			return types.Unsafe, nil
		}

		// The imports map is keyed by import path.
		ipkg := lpkg.Imports[path]
		if ipkg == nil {
			if err := lpkg.importErrors[path]; err != nil {
				return nil, err
			}
			// There was skew between the metadata and the
			// import declarations, likely due to an edit
			// race, or because the ParseFile feature was
			// used to supply alternative file contents.
			return nil, fmt.Errorf("no metadata for %s", path)
		}

		if ipkg.Types != nil && ipkg.Types.Complete() {
			return ipkg.Types, nil
		}
		log.Fatalf("internal error: package %q without types was imported from %q", path, lpkg)
		panic("unreachable")
	})

	// type-check
	tc := &types.Config{
		Importer: importer,

		// Type-check bodies of functions only in initial packages.
		// Example: for import graph A->B->C and initial packages {A,C},
		// we can ignore function bodies in B.
		IgnoreFuncBodies: ld.Mode&NeedDeps == 0 && !lpkg.initial,

		Error: appendError,
		Sizes: ld.sizes, // may be nil
	}
	if lpkg.Module != nil && lpkg.Module.GoVersion != "" {
		tc.GoVersion = "go" + lpkg.Module.GoVersion
	} else if ld.externalDriver && lpkg.goVersion != 0 {
		// Module information is missing when GOPACKAGESDRIVER is used,
		// so use the go version from the driver response.
		tc.GoVersion = fmt.Sprintf("go1.%d", lpkg.goVersion)
	}
	if (ld.Mode & typecheckCgo) != 0 {
		if !typesinternal.SetUsesCgo(tc) {
			appendError(Error{
				Msg:  "typecheckCgo requires Go 1.15+",
				Kind: ListError,
			})
			return
		}
	}

	// Type-checking is CPU intensive.
	cpuLimit <- unit{}            // acquire a token
	defer func() { <-cpuLimit }() // release a token

	typErr := types.NewChecker(tc, ld.Fset, lpkg.Types, lpkg.TypesInfo).Files(lpkg.Syntax)
	lpkg.importErrors = nil // no longer needed

	// In go/types go1.21 and go1.22, Checker.Files failed fast with a
	// a "too new" error, without calling tc.Error and without
	// proceeding to type-check the package (#66525).
	// We rely on the runtimeVersion error to give the suggested remedy.
	if typErr != nil && len(lpkg.Errors) == 0 && len(lpkg.Syntax) > 0 {
		if msg := typErr.Error(); strings.HasPrefix(msg, "package requires newer Go version") {
			appendError(types.Error{
				Fset: ld.Fset,
				Pos:  lpkg.Syntax[0].Package,
				Msg:  msg,
			})
		}
	}

	// If !Cgo, the type-checker uses FakeImportC mode, so
	// it doesn't invoke the importer for import "C",
	// nor report an error for the import,
	// or for any undefined C.f reference.
	// We must detect this explicitly and correctly
	// mark the package as IllTyped (by reporting an error).
	// TODO(adonovan): if these errors are annoying,
	// we could just set IllTyped quietly.
	if tc.FakeImportC {
	outer:
		for _, f := range lpkg.Syntax {
			for _, imp := range f.Imports {
				if imp.Path.Value == `"C"` {
					err := types.Error{Fset: ld.Fset, Pos: imp.Pos(), Msg: `import "C" ignored`}
					appendError(err)
					break outer
				}
			}
		}
	}

	// If types.Checker.Files had an error that was unreported,
	// make sure to report the unknown error so the package is illTyped.
	if typErr != nil && len(lpkg.Errors) == 0 {
		appendError(typErr)
	}

	// Record accumulated errors.
	illTyped := len(lpkg.Errors) > 0
	if !illTyped {
		for _, imp := range lpkg.Imports {
			if imp.IllTyped {
				illTyped = true
				break
			}
		}
	}
	lpkg.IllTyped = illTyped
}

func (ld *loader) newTypesInfo() *types.Info {
	// Populate TypesInfo only if needed, as it
	// causes the type checker to work much harder.
	if ld.Config.Mode&NeedTypesInfo == 0 {
		return nil
	}
	return &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Instances:    make(map[*ast.Ident]types.Instance),
		Scopes:       make(map[ast.Node]*types.Scope),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		FileVersions: make(map[*ast.File]string),
	}
}

// An importFunc is an implementation of the single-method
// types.Importer interface based on a function value.
type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }

// We use a counting semaphore to limit
// the number of parallel I/O calls or CPU threads per process.
var (
	ioLimit  = make(chan unit, 20)
	cpuLimit = make(chan unit, runtime.GOMAXPROCS(0))
)

func (ld *loader) parseFile(filename string) (*ast.File, error) {
	ld.parseCacheMu.Lock()
	v, ok := ld.parseCache[filename]
	if ok {
		// cache hit
		ld.parseCacheMu.Unlock()
		<-v.ready
	} else {
		// cache miss
		v = &parseValue{ready: make(chan struct{})}
		ld.parseCache[filename] = v
		ld.parseCacheMu.Unlock()

		var src []byte
		for f, contents := range ld.Config.Overlay {
			// TODO(adonovan): Inefficient for large overlays.
			// Do an exact name-based map lookup
			// (for nonexistent files) followed by a
			// FileID-based map lookup (for existing ones).
			if sameFile(f, filename) {
				src = contents
				break
			}
		}
		var err error
		if src == nil {
			ioLimit <- unit{} // acquire a token
			src, err = os.ReadFile(filename)
			<-ioLimit // release a token
		}
		if err != nil {
			v.err = err
		} else {
			// Parsing is CPU intensive.
			cpuLimit <- unit{} // acquire a token
			v.f, v.err = ld.ParseFile(ld.Fset, filename, src)
			<-cpuLimit // release a token
		}

		close(v.ready)
	}
	return v.f, v.err
}

// parseFiles reads and parses the Go source files and returns the ASTs
// of the ones that could be at least partially parsed, along with a
// list of I/O and parse errors encountered.
//
// Because files are scanned in parallel, the token.Pos
// positions of the resulting ast.Files are not ordered.
func (ld *loader) parseFiles(filenames []string) ([]*ast.File, []error) {
	var (
		n      = len(filenames)
		parsed = make([]*ast.File, n)
		errors = make([]error, n)
	)
	var g errgroup.Group
	for i, filename := range filenames {
		// This creates goroutines unnecessarily in the
		// cache-hit case, but that case is uncommon.
		g.Go(func() error {
			parsed[i], errors[i] = ld.parseFile(filename)
			return nil
		})
	}
	g.Wait()

	// Eliminate nils, preserving order.
	var o int
	for _, f := range parsed {
		if f != nil {
			parsed[o] = f
			o++
		}
	}
	parsed = parsed[:o]

	o = 0
	for _, err := range errors {
		if err != nil {
			errors[o] = err
			o++
		}
	}
	errors = errors[:o]

	return parsed, errors
}

// sameFile returns true if x and y have the same basename and denote
// the same file.
func sameFile(x, y string) bool {
	if x == y {
		// It could be the case that y doesn't exist.
		// For instance, it may be an overlay file that
		// hasn't been written to disk. To handle that case
		// let x == y through. (We added the exact absolute path
		// string to the CompiledGoFiles list, so the unwritten
		// overlay case implies x==y.)
		return true
	}
	if strings.EqualFold(filepath.Base(x), filepath.Base(y)) { // (optimisation)
		if xi, err := os.Stat(x); err == nil {
			if yi, err := os.Stat(y); err == nil {
				return os.SameFile(xi, yi)
			}
		}
	}
	return false
}

// loadFromExportData ensures that type information is present for the specified
// package, loading it from an export data file on the first request.
// On success it sets lpkg.Types to a new Package.
func (ld *loader) loadFromExportData(lpkg *loaderPackage) error {
	if lpkg.PkgPath == "" {
		log.Fatalf("internal error: Package %s has no PkgPath", lpkg)
	}

	// Because gcexportdata.Read has the potential to create or
	// modify the types.Package for each node in the transitive
	// closure of dependencies of lpkg, all exportdata operations
	// must be sequential. (Finer-grained locking would require
	// changes to the gcexportdata API.)
	//
	// The exportMu lock guards the lpkg.Types field and the
	// types.Package it points to, for each loaderPackage in the graph.
	//
	// Not all accesses to Package.Pkg need to be protected by exportMu:
	// graph ordering ensures that direct dependencies of source
	// packages are fully loaded before the importer reads their Pkg field.
	ld.exportMu.Lock()
	defer ld.exportMu.Unlock()

	if tpkg := lpkg.Types; tpkg != nil && tpkg.Complete() {
		return nil // cache hit
	}

	lpkg.IllTyped = true // fail safe

	if lpkg.ExportFile == "" {
		// Errors while building export data will have been printed to stderr.
		return fmt.Errorf("no export data file")
	}
	f, err := os.Open(lpkg.ExportFile)
	if err != nil {
		return err
	}
	defer f.Close()

	// Read gc export data.
	//
	// We don't currently support gccgo export data because all
	// underlying workspaces use the gc toolchain. (Even build
	// systems that support gccgo don't use it for workspace
	// queries.)
	r, err := gcexportdata.NewReader(f)
	if err != nil {
		return fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
	}

	// Build the view.
	//
	// The gcexportdata machinery has no concept of package ID.
	// It identifies packages by their PkgPath, which although not
	// globally unique is unique within the scope of one invocation
	// of the linker, type-checker, or gcexportdata.
	//
	// So, we must build a PkgPath-keyed view of the global
	// (conceptually ID-keyed) cache of packages and pass it to
	// gcexportdata. The view must contain every existing
	// package that might possibly be mentioned by the
	// current package---its transitive closure.
	//
	// In loadPackage, we unconditionally create a types.Package for
	// each dependency so that export data loading does not
	// create new ones.
	//
	// TODO(adonovan): it would be simpler and more efficient
	// if the export data machinery invoked a callback to
	// get-or-create a package instead of a map.
	//
	view := make(map[string]*types.Package) // view seen by gcexportdata
	seen := make(map[*loaderPackage]bool)   // all visited packages
	var visit func(pkgs map[string]*Package)
	visit = func(pkgs map[string]*Package) {
		for _, p := range pkgs {
			lpkg := ld.pkgs[p.ID]
			if !seen[lpkg] {
				seen[lpkg] = true
				view[lpkg.PkgPath] = lpkg.Types
				visit(lpkg.Imports)
			}
		}
	}
	visit(lpkg.Imports)

	viewLen := len(view) + 1 // adding the self package
	// Parse the export data.
	// (May modify incomplete packages in view but not create new ones.)
	tpkg, err := gcexportdata.Read(r, ld.Fset, view, lpkg.PkgPath)
	if err != nil {
		return fmt.Errorf("reading %s: %v", lpkg.ExportFile, err)
	}
	if _, ok := view["go.shape"]; ok {
		// Account for the pseudopackage "go.shape" that gets
		// created by generic code.
		viewLen++
	}
	if viewLen != len(view) {
		log.Panicf("golang.org/x/tools/go/packages: unexpected new packages during load of %s", lpkg.PkgPath)
	}

	lpkg.Types = tpkg
	lpkg.IllTyped = false
	return nil
}

// impliedLoadMode returns loadMode with its dependencies.
func impliedLoadMode(loadMode LoadMode) LoadMode {
	if loadMode&(NeedDeps|NeedTypes|NeedTypesInfo) != 0 {
		// All these things require knowing the import graph.
		loadMode |= NeedImports
	}
	if loadMode&NeedTypes != 0 {
		// Types require the GoVersion from Module.
		loadMode |= NeedModule
	}

	return loadMode
}

func usesExportData(cfg *Config) bool {
	return cfg.Mode&NeedExportFile != 0 || cfg.Mode&NeedTypes != 0 && cfg.Mode&NeedDeps == 0
}

type unit struct{}


================================================
FILE: go/packages/packages_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages_test

import (
	"bytes"
	"encoding/json"
	"fmt"
	"go/ast"
	constantpkg "go/constant"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"slices"
	"sort"
	"strings"
	"testing"
	"testing/fstest"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/packagestest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestMain(m *testing.M) {
	testenv.ExitIfSmallMachine()

	os.Exit(m.Run())
}

func skipIfShort(t *testing.T, reason string) {
	if testing.Short() {
		t.Skipf("skipping slow test in short mode: %s", reason)
	}
}

// testAllOrModulesParallel tests f, in parallel, against all packagestest
// exporters in long mode, but only against the Modules exporter in short mode.
func testAllOrModulesParallel(t *testing.T, f func(*testing.T, packagestest.Exporter)) {
	t.Parallel()
	packagestest.TestAll(t, func(t *testing.T, exporter packagestest.Exporter) {
		t.Helper()

		switch exporter.Name() {
		case "Modules":
		case "GOPATH":
			if testing.Short() {
				t.Skipf("skipping GOPATH test in short mode")
			}
		default:
			t.Fatalf("unexpected exporter %q", exporter.Name())
		}

		t.Parallel()
		f(t, exporter)
	})
}

// TODO(adonovan): more test cases to write:
//
// - When the tests fail, make them print a 'cd & load' command
//   that will allow the maintainer to interact with the failing scenario.
// - errors in go-list metadata
// - a foo.test package that cannot be built for some reason (e.g.
//   import error) will result in a JSON blob with no name and a
//   nonexistent testmain file in GoFiles. Test that we handle this
//   gracefully.
// - test more Flags.
//
// LoadSyntax & LoadAllSyntax modes:
//   - Fset may be user-supplied or not.
//   - Packages.Info is correctly set.
//   - typechecker configuration is honored
//   - import cycles are gracefully handled in type checker.
//   - test typechecking of generated test main and cgo.

// The zero-value of Config has LoadFiles mode.
func TestLoadZeroConfig(t *testing.T) {
	testenv.NeedsGoPackages(t)
	t.Parallel()

	initial, err := packages.Load(nil, "hash")
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) != 1 {
		t.Fatalf("got %s, want [hash]", initial)
	}
	hash := initial[0]
	// Even though the hash package has imports,
	// they are not reported.
	got := fmt.Sprintf("srcs=%v imports=%v", srcs(hash), hash.Imports)
	want := "srcs=[hash.go] imports=map[]"
	if got != want {
		t.Fatalf("got %s, want %s", got, want)
	}
}

func TestLoadImportsGraph(t *testing.T) { testAllOrModulesParallel(t, testLoadImportsGraph) }
func testLoadImportsGraph(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":             `package a; const A = 1`,
			"b/b.go":             `package b; import ("golang.org/fake/a"; _ "container/list"); var B = a.A`,
			"c/c.go":             `package c; import (_ "golang.org/fake/b"; _ "unsafe")`,
			"c/c2.go":            "// +build ignore\n\n" + `package c; import _ "fmt"`,
			"subdir/d/d.go":      `package d`,
			"subdir/d/d_test.go": `package d; import _ "math/bits"`,
			"subdir/d/x_test.go": `package d_test; import _ "golang.org/fake/subdir/d"`, // TODO(adonovan): test bad import here
			"subdir/e/d.go":      `package e`,
			"e/e.go":             `package main; import _ "golang.org/fake/b"`,
			"e/e2.go":            `package main; import _ "golang.org/fake/c"`,
			"f/f.go":             `package f`,
		}}})
	defer exported.Cleanup()
	exported.Config.Mode = packages.LoadImports
	initial, err := packages.Load(exported.Config, "golang.org/fake/c", "golang.org/fake/subdir/d", "golang.org/fake/e")
	if err != nil {
		t.Fatal(err)
	}

	// Check graph topology.
	graph, _ := importGraph(initial)
	wantGraph := `
  container/list
  golang.org/fake/a
  golang.org/fake/b
* golang.org/fake/c
* golang.org/fake/e
* golang.org/fake/subdir/d
* golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
* golang.org/fake/subdir/d.test
* golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
  math/bits
  unsafe
  golang.org/fake/b -> container/list
  golang.org/fake/b -> golang.org/fake/a
  golang.org/fake/c -> golang.org/fake/b
  golang.org/fake/c -> unsafe
  golang.org/fake/e -> golang.org/fake/b
  golang.org/fake/e -> golang.org/fake/c
  golang.org/fake/subdir/d [golang.org/fake/subdir/d.test] -> math/bits
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test] -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
`[1:]

	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	exported.Config.Tests = true
	initial, err = packages.Load(exported.Config, "golang.org/fake/c", "golang.org/fake/subdir/d", "golang.org/fake/e")
	if err != nil {
		t.Fatal(err)
	}

	// Check graph topology.
	graph, all := importGraph(initial)
	wantGraph = `
  container/list
  golang.org/fake/a
  golang.org/fake/b
* golang.org/fake/c
* golang.org/fake/e
* golang.org/fake/subdir/d
* golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
* golang.org/fake/subdir/d.test
* golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
  math/bits
  unsafe
  golang.org/fake/b -> container/list
  golang.org/fake/b -> golang.org/fake/a
  golang.org/fake/c -> golang.org/fake/b
  golang.org/fake/c -> unsafe
  golang.org/fake/e -> golang.org/fake/b
  golang.org/fake/e -> golang.org/fake/c
  golang.org/fake/subdir/d [golang.org/fake/subdir/d.test] -> math/bits
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test] -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
`[1:]

	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	// Check node information: kind, name, srcs.
	for _, test := range []struct {
		id          string
		wantName    string
		wantKind    string
		wantSrcs    string // = {Go,Other,Embed}Files
		wantIgnored string
	}{
		{"golang.org/fake/a", "a", "package", "a.go", ""},
		{"golang.org/fake/b", "b", "package", "b.go", ""},
		{"golang.org/fake/c", "c", "package", "c.go", "c2.go"}, // c2.go is ignored
		{"golang.org/fake/e", "main", "command", "e.go e2.go", ""},
		{"container/list", "list", "package", "list.go", ""},
		{"golang.org/fake/subdir/d", "d", "package", "d.go", ""},
		{"golang.org/fake/subdir/d.test", "main", "command", "0.go", ""},
		{"unsafe", "unsafe", "package", "unsafe.go", ""},
	} {
		p, ok := all[test.id]
		if !ok {
			t.Errorf("no package %s", test.id)
			continue
		}
		if p.Name != test.wantName {
			t.Errorf("%s.Name = %q, want %q", test.id, p.Name, test.wantName)
		}

		// kind
		var kind string
		if p.Name == "main" {
			kind += "command"
		} else {
			kind += "package"
		}
		if kind != test.wantKind {
			t.Errorf("%s.Kind = %q, want %q", test.id, kind, test.wantKind)
		}

		if srcs := strings.Join(srcs(p), " "); srcs != test.wantSrcs {
			t.Errorf("%s.{Go,Other,Embed}Files = [%s], want [%s]", test.id, srcs, test.wantSrcs)
		}
		if ignored := strings.Join(cleanPaths(p.IgnoredFiles), " "); ignored != test.wantIgnored {
			t.Errorf("%s.IgnoredFiles = [%s], want [%s]", test.id, ignored, test.wantIgnored)
		}
	}

	// Test an ad-hoc package, analogous to "go run hello.go".
	if initial, err := packages.Load(exported.Config, exported.File("golang.org/fake", "c/c.go")); len(initial) == 0 {
		t.Errorf("failed to obtain metadata for ad-hoc package: %s", err)
	} else {
		got := fmt.Sprintf("%s %s", initial[0].ID, srcs(initial[0]))
		if want := "command-line-arguments [c.go]"; got != want {
			t.Errorf("oops: got %s, want %s", got, want)
		}
	}

	// Wildcards
	// See StdlibTest for effective test of "std" wildcard.
	// TODO(adonovan): test "all" returns everything in the current module.
	{
		// "..." (subdirectory)
		initial, err = packages.Load(exported.Config, "golang.org/fake/subdir/...")
		if err != nil {
			t.Fatal(err)
		}
		graph, _ = importGraph(initial)
		wantGraph = `
* golang.org/fake/subdir/d
* golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
* golang.org/fake/subdir/d.test
* golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
* golang.org/fake/subdir/e
  math/bits
  golang.org/fake/subdir/d [golang.org/fake/subdir/d.test] -> math/bits
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d.test -> golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test]
  golang.org/fake/subdir/d_test [golang.org/fake/subdir/d.test] -> golang.org/fake/subdir/d [golang.org/fake/subdir/d.test]
`[1:]

		if graph != wantGraph {
			t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
		}
	}
}

func TestLoadImportsTestVariants(t *testing.T) {
	testAllOrModulesParallel(t, testLoadImportsTestVariants)
}
func testLoadImportsTestVariants(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":       `package a; import _ "golang.org/fake/b"`,
			"b/b.go":       `package b`,
			"b/b_test.go":  `package b`,
			"b/bx_test.go": `package b_test; import _ "golang.org/fake/a"`,
		}}})
	defer exported.Cleanup()
	exported.Config.Mode = packages.LoadImports
	exported.Config.Tests = true

	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/b")
	if err != nil {
		t.Fatal(err)
	}

	// Check graph topology.
	graph, _ := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/a [golang.org/fake/b.test]
* golang.org/fake/b
* golang.org/fake/b [golang.org/fake/b.test]
* golang.org/fake/b.test
* golang.org/fake/b_test [golang.org/fake/b.test]
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/a [golang.org/fake/b.test] -> golang.org/fake/b [golang.org/fake/b.test]
  golang.org/fake/b.test -> golang.org/fake/b [golang.org/fake/b.test]
  golang.org/fake/b.test -> golang.org/fake/b_test [golang.org/fake/b.test]
  golang.org/fake/b_test [golang.org/fake/b.test] -> golang.org/fake/a [golang.org/fake/b.test]
`[1:]

	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

func TestLoadAbsolutePath(t *testing.T) {
	t.Parallel()

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/gopatha",
		Files: map[string]any{
			"a/a.go": `package a`,
		}}, {
		Name: "golang.org/gopathb",
		Files: map[string]any{
			"b/b.go": `package b`,
		}}})
	defer exported.Cleanup()

	initial, err := packages.Load(exported.Config, filepath.Dir(exported.File("golang.org/gopatha", "a/a.go")), filepath.Dir(exported.File("golang.org/gopathb", "b/b.go")))
	if err != nil {
		t.Fatalf("failed to load imports: %v", err)
	}

	got := []string{}
	for _, p := range initial {
		got = append(got, p.ID)
	}
	sort.Strings(got)
	want := []string{"golang.org/gopatha/a", "golang.org/gopathb/b"}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("initial packages loaded: got [%s], want [%s]", got, want)
	}
}

func TestLoadArgumentListIsNotTooLong(t *testing.T) {
	// NOTE: this test adds about 2s to the test suite running time

	t.Parallel()

	// using the real ARG_MAX for some platforms increases the running time of this test by a lot,
	// 1_000_000 seems like enough to break Windows and macOS if Load doesn't split provided patterns
	argMax := 1_000_000
	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/mod",
		Files: map[string]any{
			"main.go": `package main"`,
		}}})
	defer exported.Cleanup()
	numOfPatterns := argMax/16 + 1 // the pattern below is approx. 16 chars
	patterns := make([]string, numOfPatterns)
	for i := range numOfPatterns {
		patterns[i] = fmt.Sprintf("golang.org/mod/p%d", i)
	} // patterns have more than argMax number of chars combined with whitespaces b/w patterns

	_, err := packages.Load(exported.Config, patterns...)
	if err != nil {
		t.Fatalf("failed to load: %v", err)
	}
}

func TestLoadSamePackageMultipleChunks(t *testing.T) {
	t.Parallel()

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/def.go": `package a; const SharedConstant = 42`,
		}}})
	defer exported.Cleanup()

	defFile := exported.File("golang.org/fake", "a/def.go")

	// Force chunking (exceed ~16KB arg limit)
	var files []string
	files = append(files, defFile)

	for i := 0; i < 200; i++ {
		fillerPath := filepath.Join(filepath.Dir(defFile), fmt.Sprintf("filler_%03d.go", i))
		if err := os.WriteFile(fillerPath, []byte("package a\n"), 0644); err != nil {
			t.Fatal(err)
		}
		files = append(files, fillerPath)
	}

	exported.Config.Mode = packages.NeedFiles
	pkgs, err := packages.Load(exported.Config, files...)
	if err != nil {
		t.Fatal(err)
	}

	if len(pkgs) == 0 {
		t.Fatal("package golang.org/fake/a not found")
	}

	if len(pkgs[0].GoFiles) != len(files) {
		t.Errorf("expected %d files, got %d", len(files), len(pkgs[0].GoFiles))
	}
}

// TestLoadDoesNotInvokeGit ensures that the expensive and unnecessary VCS check is skipped;
// see go.dev/issue/51999 and go.dev/issue/77419.
func TestLoadDoesNotInvokeGit(t *testing.T) {
	testenv.NeedsGoPackages(t)
	t.Parallel()

	exported := packagestest.Export(t, packagestest.Modules, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"main.go": `package main; func main() {}`,
		}}})
	defer exported.Cleanup()

	// mock a git repository by creating a .git directory
	modRoot := filepath.Dir(exported.File("golang.org/fake", "main.go"))
	if err := os.MkdirAll(filepath.Join(modRoot, ".git"), 0755); err != nil {
		t.Fatalf("creating .git: %v", err)
	}

	fakeGitDir := buildFakeGit(t, exported.Config.Env)

	pathVar := "PATH"
	if runtime.GOOS == "plan9" {
		pathVar = "path"
	}
	exported.Config.Env = prependPath(exported.Config.Env, pathVar, fakeGitDir)
	// NeedTypes triggers usesExportData, which sets -export=true on the go list invocation
	exported.Config.Mode = packages.NeedTypes

	pkgs, err := packages.Load(exported.Config, "golang.org/fake")
	if err != nil {
		t.Fatalf("packages.Load: %v", err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("packages.Load: expected 1 package, got %d: %v", len(pkgs), pkgs)
	}
	if len(pkgs[0].Errors) > 0 {
		// Assume the failure was due to the fake git command being executed.
		t.Fatalf("packages.Load: unexpected errors (git should not have been called): %v", pkgs[0].Errors)
	}
}

// buildFakeGit returns a directory containing a "git" executable that exits 1.
func buildFakeGit(t *testing.T, env []string) string {
	t.Helper()

	tmpdir := t.TempDir()
	gitName := "git"
	if runtime.GOOS == "windows" {
		gitName = "git.exe"
	}
	src := filepath.Join(tmpdir, "main.go")
	if err := os.WriteFile(src, []byte(`package main; func main() { panic("git executed") }`), 0644); err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command("go", "build", "-o", gitName, "main.go")
	cmd.Dir = tmpdir
	cmd.Env = env
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Fatalf("building fake git: %v\n%s", err, out)
	}
	return tmpdir
}

func prependPath(env []string, key, dir string) []string {
	result := make([]string, len(env))
	copy(result, env)
	for i, v := range result {
		if val, ok := strings.CutPrefix(v, key+"="); ok {
			result[i] = key + "=" + dir + string(os.PathListSeparator) + val
			return result
		}
	}
	return append(result, key+"="+dir)
}

func TestVendorImports(t *testing.T) {
	t.Parallel()

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":          `package a; import _ "b"; import _ "golang.org/fake/c";`,
			"a/vendor/b/b.go": `package b; import _ "golang.org/fake/c"`,
			"c/c.go":          `package c; import _ "b"`,
			"c/vendor/b/b.go": `package b`,
		}}})
	defer exported.Cleanup()
	exported.Config.Mode = packages.LoadImports
	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}

	graph, all := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/a/vendor/b
* golang.org/fake/c
  golang.org/fake/c/vendor/b
  golang.org/fake/a -> golang.org/fake/a/vendor/b
  golang.org/fake/a -> golang.org/fake/c
  golang.org/fake/a/vendor/b -> golang.org/fake/c
  golang.org/fake/c -> golang.org/fake/c/vendor/b
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	for _, test := range []struct {
		pattern     string
		wantImports string
	}{
		{"golang.org/fake/a", "b:golang.org/fake/a/vendor/b golang.org/fake/c:golang.org/fake/c"},
		{"golang.org/fake/c", "b:golang.org/fake/c/vendor/b"},
		{"golang.org/fake/a/vendor/b", "golang.org/fake/c:golang.org/fake/c"},
		{"golang.org/fake/c/vendor/b", ""},
	} {
		// Test the import paths.
		pkg := all[test.pattern]
		if imports := strings.Join(imports(pkg), " "); imports != test.wantImports {
			t.Errorf("package %q: got %s, want %s", test.pattern, imports, test.wantImports)
		}
	}
}

func imports(p *packages.Package) []string {
	if p == nil {
		return nil
	}
	keys := make([]string, 0, len(p.Imports))
	for k, v := range p.Imports {
		keys = append(keys, fmt.Sprintf("%s:%s", k, v.ID))
	}
	sort.Strings(keys)
	return keys
}

func TestConfigDir(t *testing.T) { testAllOrModulesParallel(t, testConfigDir) }
func testConfigDir(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":   `package a; const Name = "a" `,
			"a/b/b.go": `package b; const Name = "a/b"`,
			"b/b.go":   `package b; const Name = "b"`,
		}}})
	defer exported.Cleanup()
	aDir := filepath.Dir(exported.File("golang.org/fake", "a/a.go"))
	bDir := filepath.Dir(exported.File("golang.org/fake", "b/b.go"))
	baseDir := filepath.Dir(aDir)

	for _, test := range []struct {
		dir     string
		pattern string
		want    string // value of Name constant
		fails   bool
	}{
		{dir: bDir, pattern: "golang.org/fake/a", want: `"a"`},
		{dir: bDir, pattern: "golang.org/fake/b", want: `"b"`},
		{dir: bDir, pattern: "./a", fails: true},
		{dir: bDir, pattern: "./b", fails: true},
		{dir: baseDir, pattern: "golang.org/fake/a", want: `"a"`},
		{dir: baseDir, pattern: "golang.org/fake/b", want: `"b"`},
		{dir: baseDir, pattern: "./a", want: `"a"`},
		{dir: baseDir, pattern: "./b", want: `"b"`},
		{dir: aDir, pattern: "golang.org/fake/a", want: `"a"`},
		{dir: aDir, pattern: "golang.org/fake/b", want: `"b"`},
		{dir: aDir, pattern: "./a", fails: true},
		{dir: aDir, pattern: "./b", want: `"a/b"`},
	} {
		exported.Config.Mode = packages.LoadSyntax // Use LoadSyntax to ensure that files can be opened.
		exported.Config.Dir = test.dir
		initial, err := packages.Load(exported.Config, test.pattern)
		var got string
		fails := false
		if err != nil {
			fails = true
		} else if len(initial) > 0 {
			if len(initial[0].Errors) > 0 {
				fails = true
			} else if c := constant(initial[0], "Name"); c != nil {
				got = c.Val().String()
			}
		}
		if got != test.want {
			t.Errorf("dir %q, pattern %q: got %s, want %s",
				test.dir, test.pattern, got, test.want)
		}
		if fails != test.fails {
			t.Errorf("dir %q, pattern %q: error %v, want %v",
				test.dir, test.pattern, fails, test.fails)
		}
	}
}

func TestConfigFlags(t *testing.T) { testAllOrModulesParallel(t, testConfigFlags) }
func testConfigFlags(t *testing.T, exporter packagestest.Exporter) {
	// Test satisfying +build line tags, with -tags flag.
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			// package a
			"a/a.go": `package a; import _ "golang.org/fake/a/b"`,
			"a/b.go": `// +build tag

package a`,
			"a/c.go": `// +build tag tag2

package a`,
			"a/d.go": `// +build tag,tag2

package a`,
			// package a/b
			"a/b/a.go": `package b`,
			"a/b/b.go": `// +build tag

package b`,
		}}})
	defer exported.Cleanup()

	for _, test := range []struct {
		pattern        string
		tags           []string
		wantSrcs       string
		wantImportSrcs string
	}{
		{`golang.org/fake/a`, []string{}, "a.go", "a.go"},
		{`golang.org/fake/a`, []string{`-tags=tag`}, "a.go b.go c.go", "a.go b.go"},
		{`golang.org/fake/a`, []string{`-tags=tag2`}, "a.go c.go", "a.go"},
		{`golang.org/fake/a`, []string{`-tags=tag tag2`}, "a.go b.go c.go d.go", "a.go b.go"},
	} {
		exported.Config.Mode = packages.LoadImports
		exported.Config.BuildFlags = test.tags

		initial, err := packages.Load(exported.Config, test.pattern)
		if err != nil {
			t.Error(err)
			continue
		}
		if len(initial) != 1 {
			t.Errorf("test tags %v: pattern %s, expected 1 package, got %d packages.", test.tags, test.pattern, len(initial))
			continue
		}
		pkg := initial[0]
		if srcs := strings.Join(srcs(pkg), " "); srcs != test.wantSrcs {
			t.Errorf("test tags %v: srcs of package %s = [%s], want [%s]", test.tags, test.pattern, srcs, test.wantSrcs)
		}
		for path, ipkg := range pkg.Imports {
			if srcs := strings.Join(srcs(ipkg), " "); srcs != test.wantImportSrcs {
				t.Errorf("build tags %v: srcs of imported package %s = [%s], want [%s]", test.tags, path, srcs, test.wantImportSrcs)
			}
		}

	}
}

func TestLoadTypes(t *testing.T) { testAllOrModulesParallel(t, testLoadTypes) }
func testLoadTypes(t *testing.T, exporter packagestest.Exporter) {
	// In LoadTypes and LoadSyntax modes, the compiler will
	// fail to generate an export data file for c, because it has
	// a type error.  The loader should fall back loading a and c
	// from source, but use the export data for b.

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"; import "golang.org/fake/c"; const A = "a" + b.B + c.C`,
			"b/b.go": `package b; const B = "b"`,
			"c/c.go": `package c; const C = "c" + 1`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadTypes
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}

	graph, all := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/b
  golang.org/fake/c
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/a -> golang.org/fake/c
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	for _, id := range []string{
		"golang.org/fake/a",
		"golang.org/fake/b",
		"golang.org/fake/c",
	} {
		p := all[id]
		if p == nil {
			t.Errorf("missing package: %s", id)
			continue
		}
		if p.Types == nil {
			t.Errorf("missing types.Package for %s", p)
			continue
		} else if !p.Types.Complete() {
			t.Errorf("incomplete types.Package for %s", p)
		} else if p.TypesSizes == nil {
			t.Errorf("TypesSizes is not filled in for %s", p)
		}

	}
}

// TestLoadTypesBits is equivalent to TestLoadTypes except that it only requests
// the types using the NeedTypes bit.
func TestLoadTypesBits(t *testing.T) { testAllOrModulesParallel(t, testLoadTypesBits) }
func testLoadTypesBits(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"; const A = "a" + b.B`,
			"b/b.go": `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
			"c/c.go": `package c; import "golang.org/fake/d"; const C = "c" + d.D`,
			"d/d.go": `package d; import "golang.org/fake/e"; const D = "d" + e.E`,
			"e/e.go": `package e; import "golang.org/fake/f"; const E = "e" + f.F`,
			"f/f.go": `package f; const F = "f"`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedTypes | packages.NeedImports
	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}

	graph, all := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/b
* golang.org/fake/c
  golang.org/fake/d
  golang.org/fake/e
  golang.org/fake/f
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/b -> golang.org/fake/c
  golang.org/fake/c -> golang.org/fake/d
  golang.org/fake/d -> golang.org/fake/e
  golang.org/fake/e -> golang.org/fake/f
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	for _, test := range []struct {
		id string
	}{
		{"golang.org/fake/a"},
		{"golang.org/fake/b"},
		{"golang.org/fake/c"},
		{"golang.org/fake/d"},
		{"golang.org/fake/e"},
		{"golang.org/fake/f"},
	} {
		p := all[test.id]
		if p == nil {
			t.Errorf("missing package: %s", test.id)
			continue
		}
		if p.Types == nil {
			t.Errorf("missing types.Package for %s", p)
			continue
		}
		// We don't request the syntax, so we shouldn't get it.
		if p.Syntax != nil {
			t.Errorf("Syntax unexpectedly provided for %s", p)
		}
		if p.Errors != nil {
			t.Errorf("errors in package: %s: %s", p, p.Errors)
		}
	}

	// Check value of constant.
	aA := constant(all["golang.org/fake/a"], "A")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	if got, want := fmt.Sprintf("%v %v", aA, aA.Val()), `const golang.org/fake/a.A untyped string "abcdef"`; got != want {
		t.Errorf("a.A: got %s, want %s", got, want)
	}
}

func TestLoadSyntaxOK(t *testing.T) { testAllOrModulesParallel(t, testLoadSyntaxOK) }
func testLoadSyntaxOK(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"; const A = "a" + b.B`,
			"b/b.go": `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
			"c/c.go": `package c; import "golang.org/fake/d"; const C = "c" + d.D`,
			"d/d.go": `package d; import "golang.org/fake/e"; const D = "d" + e.E`,
			"e/e.go": `package e; import "golang.org/fake/f"; const E = "e" + f.F`,
			"f/f.go": `package f; const F = "f"`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadSyntax
	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}

	graph, all := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/b
* golang.org/fake/c
  golang.org/fake/d
  golang.org/fake/e
  golang.org/fake/f
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/b -> golang.org/fake/c
  golang.org/fake/c -> golang.org/fake/d
  golang.org/fake/d -> golang.org/fake/e
  golang.org/fake/e -> golang.org/fake/f
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

	for _, test := range []struct {
		id           string
		wantSyntax   bool
		wantComplete bool
	}{
		{"golang.org/fake/a", true, true},   // source package
		{"golang.org/fake/b", true, true},   // source package because depends on initial package
		{"golang.org/fake/c", true, true},   // source package
		{"golang.org/fake/d", false, true},  // export data package
		{"golang.org/fake/e", false, false}, // export data package
		{"golang.org/fake/f", false, false}, // export data package
	} {
		// TODO(matloob): LoadSyntax and LoadAllSyntax are now equivalent, wantSyntax and wantComplete
		// are true for all packages in the transitive dependency set. Add test cases on the individual
		// Need* fields to check the equivalents on the new API.
		p := all[test.id]
		if p == nil {
			t.Errorf("missing package: %s", test.id)
			continue
		}
		if p.Types == nil {
			t.Errorf("missing types.Package for %s", p)
			continue
		} else if p.Types.Complete() != test.wantComplete {
			if test.wantComplete {
				t.Errorf("incomplete types.Package for %s", p)
			} else {
				t.Errorf("unexpected complete types.Package for %s", p)
			}
		}
		if (p.Syntax != nil) != test.wantSyntax {
			if test.wantSyntax {
				t.Errorf("missing ast.Files for %s", p)
			} else {
				t.Errorf("unexpected ast.Files for for %s", p)
			}
		}
		if p.Errors != nil {
			t.Errorf("errors in package: %s: %s", p, p.Errors)
		}
	}

	// Check value of constant.
	aA := constant(all["golang.org/fake/a"], "A")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	if got, want := fmt.Sprintf("%v %v", aA, aA.Val()), `const golang.org/fake/a.A untyped string "abcdef"`; got != want {
		t.Errorf("a.A: got %s, want %s", got, want)
	}
}

func TestLoadDiamondTypes(t *testing.T) { testAllOrModulesParallel(t, testLoadDiamondTypes) }
func testLoadDiamondTypes(t *testing.T, exporter packagestest.Exporter) {
	// We make a diamond dependency and check the type d.D is the same through both paths
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import ("golang.org/fake/b"; "golang.org/fake/c"); var _ = b.B == c.C`,
			"b/b.go": `package b; import "golang.org/fake/d"; var B d.D`,
			"c/c.go": `package c; import "golang.org/fake/d"; var C d.D`,
			"d/d.go": `package d; type D int`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadSyntax
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	for pkg := range packages.Postorder(initial) {
		for _, err := range pkg.Errors {
			t.Errorf("package %s: %v", pkg.ID, err)
		}
	}

	graph, _ := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
  golang.org/fake/b
  golang.org/fake/c
  golang.org/fake/d
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/a -> golang.org/fake/c
  golang.org/fake/b -> golang.org/fake/d
  golang.org/fake/c -> golang.org/fake/d
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

func TestLoadSyntaxError(t *testing.T) { testAllOrModulesParallel(t, testLoadSyntaxError) }
func testLoadSyntaxError(t *testing.T, exporter packagestest.Exporter) {
	// A type error in a lower-level package (e) prevents go list
	// from producing export data for all packages that depend on it
	// [a-e]. Only f should be loaded from export data, and the rest
	// should be IllTyped.
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"; const A = "a" + b.B`,
			"b/b.go": `package b; import "golang.org/fake/c"; const B = "b" + c.C`,
			"c/c.go": `package c; import "golang.org/fake/d"; const C = "c" + d.D`,
			"d/d.go": `package d; import "golang.org/fake/e"; const D = "d" + e.E`,
			"e/e.go": `package e; import "golang.org/fake/f"; const E = "e" + f.F + 1`, // type error
			"f/f.go": `package f; const F = "f"`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadSyntax
	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}

	all := make(map[string]*packages.Package)
	for p := range packages.Postorder(initial) {
		all[p.ID] = p
	}

	for _, test := range []struct {
		id           string
		wantSyntax   bool
		wantIllTyped bool
	}{
		{"golang.org/fake/a", true, true},
		{"golang.org/fake/b", true, true},
		{"golang.org/fake/c", true, true},
		{"golang.org/fake/d", true, true},
		{"golang.org/fake/e", true, true},
		{"golang.org/fake/f", false, false},
	} {
		p := all[test.id]
		if p == nil {
			t.Errorf("missing package: %s", test.id)
			continue
		}
		if p.Types == nil {
			t.Errorf("missing types.Package for %s", p)
			continue
		} else if !p.Types.Complete() {
			t.Errorf("incomplete types.Package for %s", p)
		}
		if (p.Syntax != nil) != test.wantSyntax {
			if test.wantSyntax {
				t.Errorf("missing ast.Files for %s", test.id)
			} else {
				t.Errorf("unexpected ast.Files for for %s", test.id)
			}
		}
		if p.IllTyped != test.wantIllTyped {
			t.Errorf("IllTyped was %t for %s", p.IllTyped, test.id)
		}
	}

	// Check value of constant.
	aA := constant(all["golang.org/fake/a"], "A")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	if got, want := aA.String(), `const golang.org/fake/a.A invalid type`; got != want {
		t.Errorf("a.A: got %s, want %s", got, want)
	}
}

// This function tests use of the ParseFile hook to modify
// the AST after parsing.
func TestParseFileModifyAST(t *testing.T) { testAllOrModulesParallel(t, testParseFileModifyAST) }
func testParseFileModifyAST(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; const A = "a" `,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadAllSyntax
	exported.Config.ParseFile = func(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
		const mode = parser.AllErrors | parser.ParseComments
		f, err := parser.ParseFile(fset, filename, src, mode)
		// modify AST to change `const A = "a"` to `const A = "b"`
		spec := f.Decls[0].(*ast.GenDecl).Specs[0].(*ast.ValueSpec)
		spec.Values[0].(*ast.BasicLit).Value = `"b"`
		return f, err
	}
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Error(err)
	}

	// Check value of a.A has been set to "b"
	a := initial[0]
	got := constant(a, "A").Val().String()
	if got != `"b"` {
		t.Errorf("a.A: got %s, want %s", got, `"b"`)
	}
}

func TestAdHocPackagesBadImport(t *testing.T) {
	t.Parallel()
	testenv.NeedsTool(t, "go")

	// This test doesn't use packagestest because we are testing ad-hoc packages,
	// which are outside of $GOPATH and outside of a module.
	tmp, err := os.MkdirTemp("", "a")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmp)

	filename := filepath.Join(tmp, "a.go")
	content := []byte(`package a
import _ "badimport"
const A = 1
`)
	if err := os.WriteFile(filename, content, 0775); err != nil {
		t.Fatal(err)
	}

	// Make sure that the user's value of GO111MODULE does not affect test results.
	for _, go111module := range []string{"off", "auto", "on"} {
		config := &packages.Config{
			Env:  append(os.Environ(), "GOPACKAGESDRIVER=off", fmt.Sprintf("GO111MODULE=%s", go111module)),
			Dir:  tmp,
			Mode: packages.LoadAllSyntax,
			Logf: t.Logf,
		}
		initial, err := packages.Load(config, fmt.Sprintf("file=%s", filename))
		if err != nil {
			t.Error(err)
		}
		if len(initial) == 0 {
			t.Fatalf("no packages for %s with GO111MODULE=%s", filename, go111module)
		}
		// Check value of a.A.
		a := initial[0]
		// There's an error because there's a bad import.
		aA := constant(a, "A")
		if aA == nil {
			t.Errorf("a.A: got nil")
			return
		}
		got := aA.Val().String()
		if want := "1"; got != want {
			t.Errorf("a.A: got %s, want %s", got, want)
		}
	}
}

func TestLoadAllSyntaxImportErrors(t *testing.T) {
	testAllOrModulesParallel(t, testLoadAllSyntaxImportErrors)
}
func testLoadAllSyntaxImportErrors(t *testing.T, exporter packagestest.Exporter) {
	// TODO(matloob): Remove this once go list -e -compiled is fixed.
	// See https://golang.org/issue/26755
	t.Skip("go list -compiled -e fails with non-zero exit status for empty packages")

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"unicycle/unicycle.go": `package unicycle; import _ "unicycle"`,
			"bicycle1/bicycle1.go": `package bicycle1; import _ "bicycle2"`,
			"bicycle2/bicycle2.go": `package bicycle2; import _ "bicycle1"`,
			"bad/bad.go":           `not a package declaration`,
			"empty/README.txt":     `not a go file`,
			"root/root.go": `package root
import (
	_ "bicycle1"
	_ "unicycle"
	_ "nonesuch"
	_ "empty"
	_ "bad"
)`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadAllSyntax
	initial, err := packages.Load(exported.Config, "root")
	if err != nil {
		t.Fatal(err)
	}

	// Cycle-forming edges are removed from the graph:
	// 	bicycle2 -> bicycle1
	//      unicycle -> unicycle
	graph, all := importGraph(initial)
	wantGraph := `
  bicycle1
  bicycle2
* root
  unicycle
  bicycle1 -> bicycle2
  root -> bicycle1
  root -> unicycle
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
	for _, test := range []struct {
		id       string
		wantErrs []string
	}{
		{"bicycle1", nil},
		{"bicycle2", []string{
			"could not import bicycle1 (import cycle: [root bicycle1 bicycle2])",
		}},
		{"unicycle", []string{
			"could not import unicycle (import cycle: [root unicycle])",
		}},
		{"root", []string{
			`could not import bad (missing package: "bad")`,
			`could not import empty (missing package: "empty")`,
			`could not import nonesuch (missing package: "nonesuch")`,
		}},
	} {
		p := all[test.id]
		if p == nil {
			t.Errorf("missing package: %s", test.id)
			continue
		}
		if p.Types == nil {
			t.Errorf("missing types.Package for %s", test.id)
		}
		if p.Syntax == nil {
			t.Errorf("missing ast.Files for %s", test.id)
		}
		if !p.IllTyped {
			t.Errorf("IllTyped was false for %s", test.id)
		}
		if errs := errorMessages(p.Errors); !reflect.DeepEqual(errs, test.wantErrs) {
			t.Errorf("in package %s, got errors %s, want %s", p, errs, test.wantErrs)
		}
	}
}

func TestAbsoluteFilenames(t *testing.T) { testAllOrModulesParallel(t, testAbsoluteFilenames) }
func testAbsoluteFilenames(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":          `package a; const A = 1`,
			"b/b.go":          `package b; import ("golang.org/fake/a"; _ "errors"); var B = a.A`,
			"b/vendor/a/a.go": `package a; const A = 1`,
			"c/c.go":          `package c; import (_ "golang.org/fake/b"; _ "unsafe")`,
			"c/c2.go":         "// +build ignore\n\n" + `package c; import _ "fmt"`,
			"subdir/d/d.go":   `package d`,
			"subdir/e/d.go":   `package e`,
			"e/e.go":          `package main; import _ "golang.org/fake/b"`,
			"e/e2.go":         `package main; import _ "golang.org/fake/c"`,
			"f/f.go":          `package f`,
			"f/f.s":           ``,
			"g/g.go":          `package g; import _ "embed";` + "\n//go:embed g2.txt\n" + `var s string`,
			"g/g2.txt":        "hello",
			"h/h.go":          `package g; import _ "embed";` + "\n//go:embed a*.txt\n" + `var s string`,
			"h/aa.txt":        "hello",
		}}})
	defer exported.Cleanup()
	exported.Config.Dir = filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "a/a.go")))

	checkFile := func(filename string) {
		if !filepath.IsAbs(filename) {
			t.Errorf("filename is not absolute: %s", filename)
		}
		if _, err := os.Stat(filename); err != nil {
			t.Errorf("stat error, %s: %v", filename, err)
		}
	}

	for _, test := range []struct {
		pattern string
		want    string
	}{
		// Import paths
		{"golang.org/fake/a", "a.go"},
		{"golang.org/fake/b/vendor/a", "a.go"},
		{"golang.org/fake/b", "b.go"},
		{"golang.org/fake/c", "c.go"},
		{"golang.org/fake/subdir/d", "d.go"},
		{"golang.org/fake/subdir/e", "d.go"},
		{"golang.org/fake/e", "e.go e2.go"},
		{"golang.org/fake/f", "f.go f.s"},
		{"golang.org/fake/g", "g.go g2.txt"},
		{"golang.org/fake/h", "h.go aa.txt"},
		// Relative paths
		{"./a", "a.go"},
		{"./b/vendor/a", "a.go"},
		{"./b", "b.go"},
		{"./c", "c.go"},
		{"./subdir/d", "d.go"},
		{"./subdir/e", "d.go"},
		{"./e", "e.go e2.go"},
		{"./f", "f.go f.s"},
		{"./g", "g.go g2.txt"},
		{"./h", "h.go aa.txt"},
	} {
		exported.Config.Mode = packages.LoadFiles | packages.NeedEmbedFiles
		pkgs, err := packages.Load(exported.Config, test.pattern)
		if err != nil {
			t.Errorf("pattern %s: %v", test.pattern, err)
			continue
		}

		if got := strings.Join(srcs(pkgs[0]), " "); got != test.want {
			t.Errorf("in package %s, got %s, want %s", test.pattern, got, test.want)
		}

		// Test that files in all packages exist and are absolute paths.
		_, all := importGraph(pkgs)
		for _, pkg := range all {
			for _, filename := range pkg.GoFiles {
				checkFile(filename)
			}
			for _, filename := range pkg.OtherFiles {
				checkFile(filename)
			}
			for _, filename := range pkg.EmbedFiles {
				checkFile(filename)
			}
			for _, filename := range pkg.IgnoredFiles {
				checkFile(filename)
			}
		}
	}
}

func TestContains(t *testing.T) { testAllOrModulesParallel(t, testContains) }
func testContains(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"`,
			"b/b.go": `package b; import "golang.org/fake/c"`,
			"c/c.go": `package c`,
		}}})
	defer exported.Cleanup()
	bFile := exported.File("golang.org/fake", "b/b.go")
	exported.Config.Mode = packages.LoadImports
	initial, err := packages.Load(exported.Config, "file="+bFile)
	if err != nil {
		t.Fatal(err)
	}

	graph, _ := importGraph(initial)
	wantGraph := `
* golang.org/fake/b
  golang.org/fake/c
  golang.org/fake/b -> golang.org/fake/c
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

// This test ensures that the effective GOARCH variable in the
// application determines the Sizes function used by the type checker.
// This behavior is a stop-gap until we make the build system's query
// tool report the correct sizes function for the actual configuration.
func TestSizes(t *testing.T) { testAllOrModulesParallel(t, testSizes) }
func testSizes(t *testing.T, exporter packagestest.Exporter) {
	// Only run this test on operating systems that have both an amd64 and 386 port.
	switch runtime.GOOS {
	case "linux", "windows", "freebsd", "openbsd", "netbsd", "android":
	default:
		t.Skipf("skipping test on %s", runtime.GOOS)
	}

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "unsafe"; const WordSize = 8*unsafe.Sizeof(int(0))`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadSyntax
	savedEnv := exported.Config.Env
	for arch, wantWordSize := range map[string]int64{"386": 32, "amd64": 64} {
		exported.Config.Env = append(savedEnv, "GOARCH="+arch)
		initial, err := packages.Load(exported.Config, "golang.org/fake/a")
		if err != nil {
			t.Fatal(err)
		}
		if packages.PrintErrors(initial) > 0 {
			t.Fatal("there were errors")
		}
		gotWordSize, _ := constantpkg.Int64Val(constant(initial[0], "WordSize").Val())
		if gotWordSize != wantWordSize {
			t.Errorf("for GOARCH=%s, got word size %d, want %d", arch, gotWordSize, wantWordSize)
		}
	}
}

// This is a regression test for a bug related to
// github.com/golang/vscode-go/issues/3021: if types are needed (any
// of NeedTypes{,Info,Sizes} and the types.Sizes cannot be obtained
// (e.g. due to a bad GOARCH) then the Load operation must fail. It
// must not return a nil TypesSizes, or use the default (wrong) size.
// (The root cause of that issue turned out to be due to skew in the
// Bazel GOPACKAGESDRIVER; see CL 537876.)
//
// We use a file=... query because it suppresses the bad-GOARCH check
// that the go command would otherwise perform eagerly.
// (Gopls relies on this as a fallback.)
func TestNeedTypeSizesWithBadGOARCH(t *testing.T) {
	testAllOrModulesParallel(t, func(t *testing.T, exporter packagestest.Exporter) {
		exported := packagestest.Export(t, exporter, []packagestest.Module{{
			Name:  "testdata",
			Files: map[string]any{"a/a.go": `package a`}}})
		defer exported.Cleanup()

		exported.Config.Mode = packages.NeedTypesSizes // or {,Info,Sizes}
		exported.Config.Env = append(exported.Config.Env, "GOARCH=286")
		_, err := packages.Load(exported.Config, "file=./a/a.go")
		got := fmt.Sprint(err)
		want := "can't determine type sizes"
		if !strings.Contains(got, want) {
			t.Errorf("Load error %q does not contain substring %q", got, want)
		}
	})
}

// TestContainsFallbackSticks ensures that when there are both contains and non-contains queries
// the decision whether to fallback to the pre-1.11 go list sticks across both sets of calls to
// go list.
func TestContainsFallbackSticks(t *testing.T) {
	testAllOrModulesParallel(t, testContainsFallbackSticks)
}
func testContainsFallbackSticks(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import "golang.org/fake/b"`,
			"b/b.go": `package b; import "golang.org/fake/c"`,
			"c/c.go": `package c`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadImports
	bFile := exported.File("golang.org/fake", "b/b.go")
	initial, err := packages.Load(exported.Config, "golang.org/fake/a", "file="+bFile)
	if err != nil {
		t.Fatal(err)
	}

	graph, _ := importGraph(initial)
	wantGraph := `
* golang.org/fake/a
* golang.org/fake/b
  golang.org/fake/c
  golang.org/fake/a -> golang.org/fake/b
  golang.org/fake/b -> golang.org/fake/c
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}
}

// Test that Load with no patterns is equivalent to loading "." via the golist
// driver.
func TestNoPatterns(t *testing.T) { testAllOrModulesParallel(t, testNoPatterns) }
func testNoPatterns(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":   `package a;`,
			"a/b/b.go": `package b;`,
		}}})
	defer exported.Cleanup()

	aDir := filepath.Dir(exported.File("golang.org/fake", "a/a.go"))
	exported.Config.Dir = aDir

	initial, err := packages.Load(exported.Config)
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) != 1 || initial[0].Name != "a" {
		t.Fatalf(`Load() = %v, wanted just the package in the current directory`, initial)
	}
}

func TestJSON(t *testing.T) { testAllOrModulesParallel(t, testJSON) }
func testJSON(t *testing.T, exporter packagestest.Exporter) {
	// TODO: add in some errors
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; const A = 1`,
			"b/b.go": `package b; import "golang.org/fake/a"; var B = a.A`,
			"c/c.go": `package c; import "golang.org/fake/b" ; var C = b.B`,
			"d/d.go": `package d; import "golang.org/fake/b" ; var D = b.B`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadImports
	initial, err := packages.Load(exported.Config, "golang.org/fake/c", "golang.org/fake/d")
	if err != nil {
		t.Fatal(err)
	}

	// Visit and print all packages.
	buf := &bytes.Buffer{}
	enc := json.NewEncoder(buf)
	enc.SetIndent("", "\t")
	for pkg := range packages.Postorder(initial) {
		// trim the source lists for stable results
		pkg.GoFiles = cleanPaths(pkg.GoFiles)
		pkg.CompiledGoFiles = cleanPaths(pkg.CompiledGoFiles)
		pkg.OtherFiles = cleanPaths(pkg.OtherFiles)
		pkg.IgnoredFiles = cleanPaths(pkg.IgnoredFiles)
		if err := enc.Encode(pkg); err != nil {
			t.Fatal(err)
		}
	}

	wantJSON := `
{
	"ID": "golang.org/fake/a",
	"Name": "a",
	"PkgPath": "golang.org/fake/a",
	"GoFiles": [
		"a.go"
	],
	"CompiledGoFiles": [
		"a.go"
	]
}
{
	"ID": "golang.org/fake/b",
	"Name": "b",
	"PkgPath": "golang.org/fake/b",
	"GoFiles": [
		"b.go"
	],
	"CompiledGoFiles": [
		"b.go"
	],
	"Imports": {
		"golang.org/fake/a": "golang.org/fake/a"
	}
}
{
	"ID": "golang.org/fake/c",
	"Name": "c",
	"PkgPath": "golang.org/fake/c",
	"GoFiles": [
		"c.go"
	],
	"CompiledGoFiles": [
		"c.go"
	],
	"Imports": {
		"golang.org/fake/b": "golang.org/fake/b"
	}
}
{
	"ID": "golang.org/fake/d",
	"Name": "d",
	"PkgPath": "golang.org/fake/d",
	"GoFiles": [
		"d.go"
	],
	"CompiledGoFiles": [
		"d.go"
	],
	"Imports": {
		"golang.org/fake/b": "golang.org/fake/b"
	}
}
`[1:]

	if buf.String() != wantJSON {
		t.Errorf("wrong JSON: got <<%s>>, want <<%s>>", buf.String(), wantJSON)
	}
	// now decode it again
	var decoded []*packages.Package
	dec := json.NewDecoder(buf)
	for dec.More() {
		p := new(packages.Package)
		if err := dec.Decode(p); err != nil {
			t.Fatal(err)
		}
		decoded = append(decoded, p)
	}
	if len(decoded) != 4 {
		t.Fatalf("got %d packages, want 4", len(decoded))
	}
	for i, want := range []*packages.Package{{
		ID:   "golang.org/fake/a",
		Name: "a",
	}, {
		ID:   "golang.org/fake/b",
		Name: "b",
		Imports: map[string]*packages.Package{
			"golang.org/fake/a": {ID: "golang.org/fake/a"},
		},
	}, {
		ID:   "golang.org/fake/c",
		Name: "c",
		Imports: map[string]*packages.Package{
			"golang.org/fake/b": {ID: "golang.org/fake/b"},
		},
	}, {
		ID:   "golang.org/fake/d",
		Name: "d",
		Imports: map[string]*packages.Package{
			"golang.org/fake/b": {ID: "golang.org/fake/b"},
		},
	}} {
		got := decoded[i]
		if got.ID != want.ID {
			t.Errorf("Package %d has ID %q want %q", i, got.ID, want.ID)
		}
		if got.Name != want.Name {
			t.Errorf("Package %q has Name %q want %q", got.ID, got.Name, want.Name)
		}
		if len(got.Imports) != len(want.Imports) {
			t.Errorf("Package %q has %d imports want %d", got.ID, len(got.Imports), len(want.Imports))
			continue
		}
		for path, ipkg := range got.Imports {
			if want.Imports[path] == nil {
				t.Errorf("Package %q has unexpected import %q", got.ID, path)
				continue
			}
			if want.Imports[path].ID != ipkg.ID {
				t.Errorf("Package %q import %q is %q want %q", got.ID, path, ipkg.ID, want.Imports[path].ID)
			}
		}
	}
}

func TestRejectInvalidQueries(t *testing.T) {
	t.Parallel()

	queries := []string{"key=", "key=value"}
	cfg := &packages.Config{
		Mode: packages.LoadImports,
		Env:  append(os.Environ(), "GO111MODULE=off", "GOPACKAGESDRIVER=off"),
	}
	for _, q := range queries {
		if _, err := packages.Load(cfg, q); err == nil {
			t.Errorf("packages.Load(%q) succeeded. Expected \"invalid query type\" error", q)
		} else if !strings.Contains(err.Error(), "invalid query type") {
			t.Errorf("packages.Load(%q): got error %v, want \"invalid query type\" error", q, err)
		}
	}
}

func TestPatternPassthrough(t *testing.T) { testAllOrModulesParallel(t, testPatternPassthrough) }
func testPatternPassthrough(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a;`,
		}}})
	defer exported.Cleanup()

	initial, err := packages.Load(exported.Config, "pattern=a")
	if err != nil {
		t.Fatal(err)
	}

	graph, _ := importGraph(initial)
	wantGraph := `
* a
`[1:]
	if graph != wantGraph {
		t.Errorf("wrong import graph: got <<%s>>, want <<%s>>", graph, wantGraph)
	}

}

func TestConfigDefaultEnv(t *testing.T) {
	// packagestest.TestAll instead of testAllOrModulesParallel because this test
	// can't be parallelized (it modifies the environment).
	packagestest.TestAll(t, testConfigDefaultEnv)
}
func testConfigDefaultEnv(t *testing.T, exporter packagestest.Exporter) {
	const driverJSON = `{
  "Roots": ["gopackagesdriver"],
  "Packages": [{"ID": "gopackagesdriver", "Name": "gopackagesdriver"}]
}`
	var (
		pathKey      string
		driverScript packagestest.Writer
	)
	switch runtime.GOOS {
	case "android":
		t.Skip("doesn't run on android")
	case "windows":
		// TODO(jayconrod): write an equivalent batch script for windows.
		// Hint: "type" can be used to read a file to stdout.
		t.Skip("test requires sh")
	case "plan9":
		pathKey = "path"
		driverScript = packagestest.Script(`#!/bin/rc

cat <<'EOF'
` + driverJSON + `
EOF
`)
	default:
		pathKey = "PATH"
		driverScript = packagestest.Script(`#!/bin/sh

cat - <<'EOF'
` + driverJSON + `
EOF
`)
	}
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"bin/gopackagesdriver": driverScript,
			"golist/golist.go":     "package golist",
		}}})
	defer exported.Cleanup()
	driver := exported.File("golang.org/fake", "bin/gopackagesdriver")
	binDir := filepath.Dir(driver)
	if err := os.Chmod(driver, 0755); err != nil {
		t.Fatal(err)
	}

	path, ok := os.LookupEnv(pathKey)
	var pathWithDriver string
	if ok {
		pathWithDriver = binDir + string(os.PathListSeparator) + path
	} else {
		pathWithDriver = binDir
	}
	for _, test := range []struct {
		desc    string
		path    string
		driver  string
		wantIDs string
	}{
		{
			desc:    "driver_off",
			path:    pathWithDriver,
			driver:  "off",
			wantIDs: "[golist]",
		}, {
			desc:    "driver_unset",
			path:    pathWithDriver,
			driver:  "",
			wantIDs: "[gopackagesdriver]",
		}, {
			desc:    "driver_set",
			path:    "",
			driver:  driver,
			wantIDs: "[gopackagesdriver]",
		},
	} {
		t.Run(test.desc, func(t *testing.T) {
			oldPath := os.Getenv(pathKey)
			os.Setenv(pathKey, test.path)
			defer os.Setenv(pathKey, oldPath)
			// Clone exported.Config
			config := exported.Config
			config.Env = slices.Clone(exported.Config.Env)
			config.Env = append(config.Env, "GOPACKAGESDRIVER="+test.driver)
			pkgs, err := packages.Load(exported.Config, "golist")
			if err != nil {
				t.Fatal(err)
			}

			gotIds := make([]string, len(pkgs))
			for i, pkg := range pkgs {
				gotIds[i] = pkg.ID
			}
			if fmt.Sprint(pkgs) != test.wantIDs {
				t.Errorf("got %v; want %v", gotIds, test.wantIDs)
			}
		})
	}
}

// This test that a simple x test package layout loads correctly.
// There was a bug in go list where it returned multiple copies of the same
// package (specifically in this case of golang.org/fake/a), and this triggered
// a bug in go/packages where it would leave an empty entry in the root package
// list. This would then cause a nil pointer crash.
// This bug was triggered by the simple package layout below, and thus this
// test will make sure the bug remains fixed.
func TestBasicXTest(t *testing.T) { testAllOrModulesParallel(t, testBasicXTest) }
func testBasicXTest(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":      `package a;`,
			"a/a_test.go": `package a_test;`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadFiles
	exported.Config.Tests = true
	_, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
}

func TestErrorMissingFile(t *testing.T) { testAllOrModulesParallel(t, testErrorMissingFile) }
func testErrorMissingFile(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a_test.go": `package a;`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadSyntax
	exported.Config.Tests = false
	pkgs, err := packages.Load(exported.Config, "missing.go")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) == 0 && runtime.GOOS == "windows" {
		t.Skip("Issue #31344: the ad-hoc command-line-arguments package isn't created on windows")
	}
	if len(pkgs) != 1 || (pkgs[0].PkgPath != "command-line-arguments" && pkgs[0].PkgPath != "missing.go") {
		t.Fatalf("packages.Load: want [command-line-arguments] or [missing.go], got %v", pkgs)
	}
	if len(pkgs[0].Errors) == 0 {
		t.Errorf("result of Load: want package with errors, got none: %+v", pkgs[0])
	}
}

func TestReturnErrorWhenUsingNonGoFiles(t *testing.T) {
	testAllOrModulesParallel(t, testReturnErrorWhenUsingNonGoFiles)
}
func testReturnErrorWhenUsingNonGoFiles(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/gopatha",
		Files: map[string]any{
			"a/a.go": `package a`,
		}}, {
		Name: "golang.org/gopathb",
		Files: map[string]any{
			"b/b.c": `package b`,
		}}})
	defer exported.Cleanup()
	config := packages.Config{Env: append(os.Environ(), "GOPACKAGESDRIVER=off")}
	pkgs, err := packages.Load(&config, "b/b.c")
	if err != nil {
		return
	}
	// Go <1.14 calls the package command-line-arguments while Go 1.14+ uses the file names.
	if len(pkgs) != 1 || (pkgs[0].PkgPath != "command-line-arguments" && pkgs[0].PkgPath != "b/b.c") {
		t.Fatalf("packages.Load: want [command-line-arguments] or [b/b.c], got %v", pkgs)
	}
	if len(pkgs[0].Errors) != 1 {
		t.Fatalf("result of Load: want package with one error, got: %+v", pkgs[0])
	}
}

func TestReturnErrorWhenUsingGoFilesInMultipleDirectories(t *testing.T) {
	testAllOrModulesParallel(t, testReturnErrorWhenUsingGoFilesInMultipleDirectories)
}
func testReturnErrorWhenUsingGoFilesInMultipleDirectories(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/gopatha",
		Files: map[string]any{
			"a/a.go": `package a`,
			"b/b.go": `package b`,
		}}})
	defer exported.Cleanup()
	want := "named files must all be in one directory"
	pkgs, err := packages.Load(exported.Config, exported.File("golang.org/gopatha", "a/a.go"), exported.File("golang.org/gopatha", "b/b.go"))
	if err != nil {
		// Check if the error returned is the one we expected.
		if !strings.Contains(err.Error(), want) {
			t.Fatalf("want error message: %s, got: %s", want, err.Error())
		}
		return
	}
	if len(pkgs) != 1 || pkgs[0].PkgPath != "command-line-arguments" {
		t.Fatalf("packages.Load: want [command-line-arguments], got %v", pkgs)
	}
	if len(pkgs[0].Errors) != 1 {
		t.Fatalf("result of Load: want package with one error, got: %+v", pkgs[0])
	}
	got := pkgs[0].Errors[0].Error()
	if !strings.Contains(got, want) {
		t.Fatalf("want error message: %s, got: %s", want, got)
	}
}

func TestReturnErrorForUnexpectedDirectoryLayout(t *testing.T) {
	testAllOrModulesParallel(t, testReturnErrorForUnexpectedDirectoryLayout)
}
func testReturnErrorForUnexpectedDirectoryLayout(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/gopatha",
		Files: map[string]any{
			"a/testdata/a.go": `package a; import _ "b"`,
			"a/vendor/b/b.go": `package b; import _ "fmt"`,
		}}})
	defer exported.Cleanup()
	want := "unexpected directory layout"
	// triggering this error requires a relative package path
	exported.Config.Dir = filepath.Dir(exported.File("golang.org/gopatha", "a/testdata/a.go"))
	pkgs, err := packages.Load(exported.Config, ".")

	// This error doesn't seem to occur in module mode; so only
	// complain if we get zero packages while also getting no error.
	if err == nil {
		if len(pkgs) == 0 {
			// TODO(dh): we'll need to expand on the error check if/when Go stops emitting this error
			t.Fatalf("want error, got nil")
		}
		return
	}
	// Check if the error returned is the one we expected.
	if !strings.Contains(err.Error(), want) {
		t.Fatalf("want error message: %s, got: %s", want, err.Error())
	}
}

func TestMissingDependency(t *testing.T) { testAllOrModulesParallel(t, testMissingDependency) }
func testMissingDependency(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "this/package/doesnt/exist"`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.LoadAllSyntax
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 && pkgs[0].PkgPath != "golang.org/fake/a" {
		t.Fatalf("packages.Load: want [golang.org/fake/a], got %v", pkgs)
	}
	if len(pkgs[0].Errors) == 0 {
		t.Errorf("result of Load: want package with errors, got none: %+v", pkgs[0])
	}
}

func TestAdHocContains(t *testing.T) { testAllOrModulesParallel(t, testAdHocContains) }
func testAdHocContains(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a;`,
		}}})
	defer exported.Cleanup()

	tmpfile, err := os.CreateTemp("", "adhoc*.go")
	filename := tmpfile.Name()
	if err != nil {
		t.Fatal(err)
	}
	fmt.Fprint(tmpfile, `package main; import "fmt"; func main() { fmt.Println("time for coffee") }`)
	if err := tmpfile.Close(); err != nil {
		t.Fatal(err)
	}

	defer func() {
		if err := os.Remove(filename); err != nil {
			t.Fatal(err)
		}
	}()

	exported.Config.Mode = packages.NeedImports | packages.NeedFiles
	pkgs, err := packages.Load(exported.Config, "file="+filename)
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 && pkgs[0].PkgPath != "command-line-arguments" {
		t.Fatalf("packages.Load: want [command-line-arguments], got %v", pkgs)
	}
	pkg := pkgs[0]
	if _, ok := pkg.Imports["fmt"]; !ok || len(pkg.Imports) != 1 {
		t.Fatalf("Imports of loaded package: want [fmt], got %v", pkg.Imports)
	}
	if len(pkg.GoFiles) != 1 || pkg.GoFiles[0] != filename {
		t.Fatalf("GoFiles of loaded package: want [%s], got %v", filename, pkg.GoFiles)
	}
}

func TestCgoNoCcompiler(t *testing.T) { testAllOrModulesParallel(t, testCgoNoCcompiler) }
func testCgoNoCcompiler(t *testing.T, exporter packagestest.Exporter) {
	testenv.NeedsTool(t, "cgo")
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a
import "net/http"
const A = http.MethodGet
`,
		}}})
	defer exported.Cleanup()

	// Explicitly enable cgo but configure a nonexistent C compiler.
	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1", "CC=doesnotexist")
	exported.Config.Mode = packages.LoadAllSyntax
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")

	if err != nil {
		t.Fatal(err)
	}

	// Check value of a.A.
	a := initial[0]
	aA := constant(a, "A")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	got := aA.Val().String()
	if got != "\"GET\"" {
		t.Errorf("a.A: got %s, want %s", got, "\"GET\"")
	}
}

func TestCgoMissingFile(t *testing.T) { testAllOrModulesParallel(t, testCgoMissingFile) }
func testCgoMissingFile(t *testing.T, exporter packagestest.Exporter) {
	testenv.NeedsTool(t, "cgo")
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a

// #include "foo.h"
import "C"

const A = 4
`,
		}}})
	defer exported.Cleanup()

	// Explicitly enable cgo.
	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1")
	exported.Config.Mode = packages.LoadAllSyntax
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")

	if err != nil {
		t.Fatal(err)
	}

	// Check value of a.A.
	a := initial[0]
	aA := constant(a, "A")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	got := aA.Val().String()
	if got != "4" {
		t.Errorf("a.A: got %s, want %s", got, "4")
	}
}

func TestLoadImportsC(t *testing.T) {
	// This test checks that when a package depends on the
	// test variant of "syscall", "unsafe", or "runtime/cgo", that dependency
	// is not removed when those packages are added when it imports "C".
	//
	// For this test to work, the external test of syscall must have a dependency
	// on net, and net must import "syscall" and "C".
	if runtime.GOOS == "windows" {
		t.Skipf("skipping on windows; packages on windows do not satisfy conditions for test.")
	}
	if runtime.GOOS == "plan9" {
		// See https://golang.org/issue/27100.
		t.Skip(`skipping on plan9; for some reason "net [syscall.test]" is not loaded`)
	}
	t.Parallel()
	testenv.NeedsGoPackages(t)

	cfg := &packages.Config{
		Context: t.Context(),
		Mode:    packages.LoadImports,
		Tests:   true,
	}
	initial, err := packages.Load(cfg, "syscall", "net")
	if err != nil {
		t.Fatalf("failed to load imports: %v", err)
	}

	_, all := importGraph(initial)

	for _, test := range []struct {
		pattern    string
		wantImport string // an import to check for
	}{
		{"net", "syscall:syscall"},
		{"net [syscall.test]", "syscall:syscall [syscall.test]"},
		{"syscall_test [syscall.test]", "net:net [syscall.test]"},
	} {
		// Test the import paths.
		pkg := all[test.pattern]
		if pkg == nil {
			t.Errorf("package %q not loaded", test.pattern)
			continue
		}
		if imports := strings.Join(imports(pkg), " "); !strings.Contains(imports, test.wantImport) {
			t.Errorf("package %q: got \n%s, \nwant to have %s", test.pattern, imports, test.wantImport)
		}
	}
}

func TestCgoNoSyntax(t *testing.T) {
	testAllOrModulesParallel(t, testCgoNoSyntax)
}
func testCgoNoSyntax(t *testing.T, exporter packagestest.Exporter) {
	testenv.NeedsTool(t, "cgo")

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"c/c.go": `package c; import "C"`,
		},
	}})

	// Explicitly enable cgo.
	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1")

	modes := []packages.LoadMode{
		packages.NeedTypes,
		packages.NeedName | packages.NeedTypes,
		packages.NeedName | packages.NeedTypes | packages.NeedImports,
		packages.NeedName | packages.NeedTypes | packages.NeedImports | packages.NeedDeps,
		packages.NeedName | packages.NeedImports,
	}
	for _, mode := range modes {
		t.Run(fmt.Sprint(mode), func(t *testing.T) {
			exported.Config.Mode = mode
			pkgs, err := packages.Load(exported.Config, "golang.org/fake/c")
			if err != nil {
				t.Fatal(err)
			}
			if len(pkgs) != 1 {
				t.Fatalf("Expected 1 package, got %v", pkgs)
			}
			pkg := pkgs[0]
			if len(pkg.Errors) != 0 {
				t.Fatalf("Expected no errors in package, got %v", pkg.Errors)
			}
		})
	}
}

func TestCgoBadPkgConfig(t *testing.T) {
	testAllOrModulesParallel(t, testCgoBadPkgConfig)
}
func testCgoBadPkgConfig(t *testing.T, exporter packagestest.Exporter) {
	skipIfShort(t, "builds and links a fake pkgconfig binary")
	testenv.NeedsTool(t, "cgo")

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"c/c.go": `package c

// #cgo pkg-config: --cflags --  foo
import "C"`,
		},
	}})

	dir := buildFakePkgconfig(t, exported.Config.Env)
	defer os.RemoveAll(dir)
	env := exported.Config.Env
	for i, v := range env {
		if strings.HasPrefix(v, "PATH=") {
			env[i] = "PATH=" + dir + string(os.PathListSeparator) + v[len("PATH="):]
		}
	}

	exported.Config.Env = append(exported.Config.Env, "CGO_ENABLED=1")

	exported.Config.Mode = packages.NeedName | packages.NeedCompiledGoFiles
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Expected 1 package, got %v", pkgs)
	}
	if pkgs[0].Name != "c" {
		t.Fatalf("Expected package to have name \"c\", got %q", pkgs[0].Name)
	}
}

func buildFakePkgconfig(t *testing.T, env []string) string {
	tmpdir, err := os.MkdirTemp("", "fakepkgconfig")
	if err != nil {
		t.Fatal(err)
	}
	err = os.WriteFile(filepath.Join(tmpdir, "pkg-config.go"), []byte(`
package main

import "fmt"
import "os"

func main() {
	fmt.Fprintln(os.Stderr, "bad")
	os.Exit(2)
}
`), 0644)
	if err != nil {
		os.RemoveAll(tmpdir)
		t.Fatal(err)
	}
	cmd := exec.Command("go", "build", "-o", "pkg-config", "pkg-config.go")
	cmd.Dir = tmpdir
	cmd.Env = env

	if b, err := cmd.CombinedOutput(); err != nil {
		os.RemoveAll(tmpdir)
		fmt.Println(os.Environ())
		t.Log(string(b))
		t.Fatal(err)
	}
	return tmpdir
}

func TestIssue32814(t *testing.T) { testAllOrModulesParallel(t, testIssue32814) }
func testIssue32814(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name:  "golang.org/fake",
		Files: map[string]any{}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedName | packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo | packages.NeedTypesSizes
	pkgs, err := packages.Load(exported.Config, "fmt")

	if err != nil {
		t.Fatal(err)
	}

	if len(pkgs) != 1 && pkgs[0].PkgPath != "fmt" {
		t.Fatalf("packages.Load: want [fmt], got %v", pkgs)
	}
	pkg := pkgs[0]
	if len(pkg.Errors) != 0 {
		t.Fatalf("Errors for fmt pkg: got %v, want none", pkg.Errors)
	}
	if !pkg.Types.Complete() {
		t.Fatalf("Types.Complete() for fmt pkg: got %v, want true", pkgs[0].Types.Complete())

	}
}

func TestLoadTypesInfoWithoutNeedDeps(t *testing.T) {
	testAllOrModulesParallel(t, testLoadTypesInfoWithoutNeedDeps)
}
func testLoadTypesInfoWithoutNeedDeps(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "golang.org/fake/b"`,
			"b/b.go": `package b`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedTypes | packages.NeedTypesInfo | packages.NeedImports
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	pkg := pkgs[0]
	if pkg.IllTyped {
		t.Fatal("Loaded package is ill typed")
	}
	const expectedImport = "golang.org/fake/b"
	if _, ok := pkg.Imports[expectedImport]; !ok || len(pkg.Imports) != 1 {
		t.Fatalf("Imports of loaded package: want [%s], got %v", expectedImport, pkg.Imports)
	}
}

func TestLoadWithNeedDeps(t *testing.T) {
	testAllOrModulesParallel(t, testLoadWithNeedDeps)
}
func testLoadWithNeedDeps(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "golang.org/fake/b"`,
			"b/b.go": `package b; import _ "golang.org/fake/c"`,
			"c/c.go": `package c`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedTypes | packages.NeedTypesInfo | packages.NeedImports | packages.NeedDeps
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Expected 1 package, got %d", len(pkgs))
	}

	pkgA := pkgs[0]
	if pkgA.IllTyped {
		t.Fatal("Loaded package is ill typed")
	}

	pkgB := pkgA.Imports["golang.org/fake/b"]
	if pkgB == nil || len(pkgA.Imports) != 1 {
		t.Fatalf("Imports of loaded package 'a' are invalid: %v", pkgA.Imports)
	}
	if pkgB.Types == nil || !pkgB.Types.Complete() || pkgB.TypesInfo == nil {
		t.Fatalf("Types of package 'b' are nil or incomplete: %v, %v", pkgB.Types, pkgB.TypesInfo)
	}

	pkgC := pkgB.Imports["golang.org/fake/c"]
	if pkgC == nil || len(pkgB.Imports) != 1 {
		t.Fatalf("Imports of loaded package 'c' are invalid: %v", pkgB.Imports)
	}
	if pkgC.Types == nil || !pkgC.Types.Complete() || pkgC.TypesInfo == nil {
		t.Fatalf("Types of package 'b' are nil or incomplete: %v, %v", pkgC.Types, pkgC.TypesInfo)
	}
}

func TestImpliedLoadMode(t *testing.T) {
	testAllOrModulesParallel(t, testImpliedLoadMode)
}
func testImpliedLoadMode(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "golang.org/fake/b"`,
			"b/b.go": `package b`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedTypes | packages.NeedTypesInfo
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Expected 1 package, got %d", len(pkgs))
	}

	pkg := pkgs[0]
	if pkg.IllTyped {
		t.Fatalf("Loaded package is ill typed: %v", pkg.Errors)
	}

	// Check that packages.NeedTypesInfo worked well.
	if !pkg.Types.Complete() {
		t.Fatalf("Loaded package types are incomplete")
	}

	// Check that implied packages.NeedImports by packages.NeedTypesInfo
	// didn't add Imports.
	if len(pkg.Imports) != 0 {
		t.Fatalf("Package imports weren't requested but were returned: %v", pkg.Imports)
	}
}

func TestIssue35331(t *testing.T) {
	testAllOrModulesParallel(t, testIssue35331)
}
func testIssue35331(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
	}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles |
		packages.NeedImports | packages.NeedDeps | packages.NeedSyntax
	exported.Config.Tests = false
	pkgs, err := packages.Load(exported.Config, "strconv")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Expected 1 package, got %v", pkgs)
	}
	for pkg := range packages.Postorder(pkgs) {
		if len(pkg.Errors) > 0 {
			t.Errorf("Expected no errors in package %q, got %v", pkg.ID, pkg.Errors)
		}
		if len(pkg.Syntax) == 0 && pkg.ID != "unsafe" {
			t.Errorf("Expected syntax on package %q, got none.", pkg.ID)
		}
	}
}

func TestMultiplePackageVersionsIssue36188(t *testing.T) {
	testAllOrModulesParallel(t, testMultiplePackageVersionsIssue36188)
}

func testMultiplePackageVersionsIssue36188(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "golang.org/fake/b"`,
			"b/b.go": `package main`,
		}}})
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a", "golang.org/fake/b")
	if err != nil {
		t.Fatal(err)
	}
	sort.Slice(pkgs, func(i, j int) bool { return pkgs[i].ID < pkgs[j].ID })
	if len(pkgs) != 2 {
		t.Fatalf("expected two packages, got %v", pkgs)
	}
	if pkgs[0].ID != "golang.org/fake/a" && pkgs[1].ID != "golang.org/fake/b" {
		t.Fatalf(`expected (sorted) IDs "golang.org/fake/a" and "golang.org/fake/b", got %q and %q`,
			pkgs[0].ID, pkgs[1].ID)
	}
	if pkgs[0].Errors == nil {
		t.Errorf(`expected error on package "golang.org/fake/a", got none`)
	}
	if pkgs[1].Errors != nil {
		t.Errorf(`expected no errors on package "golang.org/fake/b", got %v`, pkgs[1].Errors)
	}
	defer exported.Cleanup()
}

func TestLoadModeStrings(t *testing.T) {
	testcases := []struct {
		mode     packages.LoadMode
		expected string
	}{
		{
			packages.LoadMode(0),
			"LoadMode(0)",
		},
		{
			packages.NeedName,
			"NeedName",
		},
		{
			packages.NeedFiles,
			"NeedFiles",
		},
		{
			packages.NeedCompiledGoFiles,
			"NeedCompiledGoFiles",
		},
		{
			packages.NeedImports,
			"NeedImports",
		},
		{
			packages.NeedDeps,
			"NeedDeps",
		},
		{
			packages.NeedExportFile,
			"NeedExportFile",
		},
		{
			packages.NeedTypes,
			"NeedTypes",
		},
		{
			packages.NeedSyntax,
			"NeedSyntax",
		},
		{
			packages.NeedTypesInfo,
			"NeedTypesInfo",
		},
		{
			packages.NeedTypesSizes,
			"NeedTypesSizes",
		},
		{
			packages.NeedName | packages.NeedExportFile,
			"(NeedName|NeedExportFile)",
		},
		{
			packages.NeedForTest | packages.NeedTarget | packages.NeedEmbedFiles | packages.NeedEmbedPatterns,
			"(NeedForTest|NeedEmbedFiles|NeedEmbedPatterns|NeedTarget)",
		},
		{
			packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles | packages.NeedImports | packages.NeedDeps | packages.NeedExportFile | packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo | packages.NeedTypesSizes,
			"(NeedName|NeedFiles|NeedCompiledGoFiles|NeedImports|NeedDeps|NeedExportFile|NeedTypes|NeedSyntax|NeedTypesInfo|NeedTypesSizes)",
		},
		{
			packages.NeedName | packages.NeedModule,
			"(NeedName|NeedModule)",
		},
		{
			packages.NeedName | 0x100000, // off the end (future use)
			"(NeedName|0x100000)",
		},
		{
			packages.NeedName | 0x400, // needInternalDepsErrors
			"(NeedName|0x400)",
		},
		{
			0x1000,
			"LoadMode(0x1000)",
		},
	}

	for tcInd, tc := range testcases {
		t.Run(fmt.Sprintf("test-%d", tcInd), func(t *testing.T) {
			actual := tc.mode.String()
			if tc.expected != actual {
				t.Errorf("want %#v, got %#v", tc.expected, actual)
			}
		})
	}
}

func TestCycleImportStack(t *testing.T) {
	testAllOrModulesParallel(t, testCycleImportStack)
}
func testCycleImportStack(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a; import _ "golang.org/fake/b"`,
			"b/b.go": `package b; import _ "golang.org/fake/a"`,
		}}})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedName | packages.NeedImports
	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Expected 1 package, got %v", pkgs)
	}
	pkg := pkgs[0]
	if len(pkg.Errors) != 1 {
		t.Fatalf("Expected one error in package, got %v", pkg.Errors)
	}
	expected := "import cycle not allowed: import stack: [golang.org/fake/a golang.org/fake/b golang.org/fake/a]"
	if pkg.Errors[0].Msg != expected {
		t.Fatalf("Expected error %q, got %q", expected, pkg.Errors[0].Msg)
	}
}

func TestForTestField(t *testing.T) {
	testAllOrModulesParallel(t, testForTestField)
}
func testForTestField(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go":      `package a; func hello() {};`,
			"a/a_test.go": `package a; import "testing"; func TestA1(t *testing.T) {};`,
			"a/x_test.go": `package a_test; import "testing"; func TestA2(t *testing.T) {};`,
		}}})
	defer exported.Cleanup()

	// Add overlays to make sure they don't affect anything.
	exported.Config.Overlay = map[string][]byte{
		"a/a_test.go": []byte(`package a; import "testing"; func TestA1(t *testing.T) { hello(); };`),
		"a/x_test.go": []byte(`package a_test; import "testing"; func TestA2(t *testing.T) { hello(); };`),
	}
	exported.Config.Tests = true
	exported.Config.Mode = packages.NeedName | packages.NeedImports
	forTest := "golang.org/fake/a"
	pkgs, err := packages.Load(exported.Config, forTest)
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 4 {
		t.Errorf("expected 4 packages, got %v", len(pkgs))
	}
	for _, pkg := range pkgs {
		var hasTestFile bool
		for _, f := range pkg.CompiledGoFiles {
			if strings.Contains(f, "a_test.go") || strings.Contains(f, "x_test.go") {
				hasTestFile = true
				break
			}
		}
		if !hasTestFile {
			continue
		}
		if got := pkg.ForTest; got != forTest {
			t.Errorf("expected %q, got %q", forTest, got)
		}
	}
}

func TestIssue37629(t *testing.T) {
	testAllOrModulesParallel(t, testIssue37629)
}
func testIssue37629(t *testing.T, exporter packagestest.Exporter) {
	// Tests #37629. When automatic vendoring is triggered, and we try to determine
	// the module root dir for a new overlay package, we previously would do a go list -m all,
	// which is incompatible with automatic vendoring.

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"c/c2.go":             `package c`,
			"a/a.go":              `package a; import "b.com/b"; const A = b.B`,
			"vendor/b.com/b/b.go": `package b; const B = 4`,
			"vendor/modules.txt": `# b.com/b v1.0.0
## explicit
b.com/b`,
		}}, {
		Name: "b.com/b@v1.0.0",
		Files: map[string]any{
			"arbitrary.txt": "",
		}},
	})
	rootDir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "a/a.go")))
	exported.Config.Overlay = map[string][]byte{
		filepath.Join(rootDir, "c/c.go"): []byte(`package c; import "golang.org/fake/a"; const C = a.A`),
	}
	exported.Config.Env = append(exported.Config.Env, "GOFLAGS=-mod=vendor")
	exported.Config.Mode = packages.LoadAllSyntax

	defer exported.Cleanup()

	initial, err := packages.Load(exported.Config, "golang.org/fake/c")
	if err != nil {
		t.Fatal(err)
	}

	// Check value of a.A.
	a := initial[0]
	aA := constant(a, "C")
	if aA == nil {
		t.Fatalf("a.A: got nil")
	}
	got := aA.Val().String()
	if got != "4" {
		t.Errorf("a.A: got %s, want %s", got, "4")
	}
}

func TestIssue37098(t *testing.T) { testAllOrModulesParallel(t, testIssue37098) }
func testIssue37098(t *testing.T, exporter packagestest.Exporter) {
	// packages.Load should only return Go sources in
	// (*Package).CompiledGoFiles.  This tests #37098, where using SWIG to
	// causes C++ sources to be inadvertently included in
	// (*Package).CompiledGoFiles.

	if _, err := exec.LookPath("swig"); err != nil {
		t.Skip("skipping test: swig not available")
	}
	if _, err := exec.LookPath("g++"); err != nil {
		t.Skip("skipping test: g++ not available")
	}

	// Create a fake package with an empty Go source, and a SWIG interface
	// file.
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			// The "package" statement must be included for SWIG sources to
			// be generated.
			"a/a.go":      "package a",
			"a/a.swigcxx": "",
		}}})
	defer exported.Cleanup()

	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatalf("failed to load the package: %v", err)
	}
	// Try and parse each of the files
	for _, pkg := range initial {
		for _, file := range pkg.CompiledGoFiles {

			// Validate that each file can be parsed as a Go source.
			fset := token.NewFileSet()
			_, err := parser.ParseFile(fset, file, nil, parser.ImportsOnly)
			if err != nil {
				t.Errorf("Failed to parse file '%s' as a Go source: %v", file, err)

				contents, err := os.ReadFile(file)
				if err != nil {
					t.Fatalf("Failed to read the un-parsable file '%s': %v", file, err)
				}

				// Print out some of the un-parsable file to aid in debugging.
				n := len(contents)

				// Don't print the whole file if it is too large.
				const maxBytes = 1000
				if n > maxBytes {
					n = maxBytes
				}

				t.Logf("First %d bytes of un-parsable file: %s", n, contents[:n])
			}
		}
	}
}

// TestIssue56632 checks that CompiledGoFiles does not contain non-go files regardless of
// whether the NeedFiles mode bit is set.
func TestIssue56632(t *testing.T) {
	t.Parallel()
	testenv.NeedsGoBuild(t)
	testenv.NeedsTool(t, "cgo")

	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name: "golang.org/issue56632",
		Files: map[string]any{
			"a/a.go": `package a`,
			"a/a_cgo.go": `package a

import "C"`,
			"a/a.s": ``,
			"a/a.c": ``,
		}}})
	defer exported.Cleanup()

	modes := []packages.LoadMode{packages.NeedCompiledGoFiles, packages.NeedCompiledGoFiles | packages.NeedFiles, packages.NeedImports | packages.NeedCompiledGoFiles, packages.NeedImports | packages.NeedFiles | packages.NeedCompiledGoFiles}
	for _, mode := range modes {
		exported.Config.Mode = mode

		initial, err := packages.Load(exported.Config, "golang.org/issue56632/a")
		if err != nil {
			t.Fatalf("failed to load package: %v", err)
		}

		if len(initial) != 1 {
			t.Errorf("expected 3 packages, got %d", len(initial))
		}

		p := initial[0]

		if len(p.Errors) != 0 {
			t.Errorf("expected no errors, got %v", p.Errors)
		}

		for _, f := range p.CompiledGoFiles {
			if strings.HasSuffix(f, ".s") || strings.HasSuffix(f, ".c") {
				t.Errorf("expected no non-Go CompiledGoFiles, got file %q in CompiledGoFiles", f)
			}
		}
	}
}

// TestInvalidFilesInXTest checks the fix for golang/go#37971 in Go 1.15.
func TestInvalidFilesInXTest(t *testing.T) { testAllOrModulesParallel(t, testInvalidFilesInXTest) }
func testInvalidFilesInXTest(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"d/d.go":      `package d; import "net/http"; const d = http.MethodGet; func Get() string { return d; }`,
				"d/d2.go":     ``, // invalid file
				"d/d_test.go": `package d_test; import "testing"; import "golang.org/fake/d"; func TestD(t *testing.T) { d.Get(); }`,
			},
		},
	})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedName | packages.NeedFiles
	exported.Config.Tests = true

	initial, err := packages.Load(exported.Config, "golang.org/fake/d")
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) != 3 {
		t.Errorf("expected 3 packages, got %d", len(initial))
	}
}

func TestTypecheckCgo(t *testing.T) { testAllOrModulesParallel(t, testTypecheckCgo) }
func testTypecheckCgo(t *testing.T, exporter packagestest.Exporter) {
	testenv.NeedsTool(t, "cgo")

	const cgo = `package cgo
		import "C"

		func Example() {
			C.CString("hi")
		}
	`
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"cgo/cgo.go": cgo,
			},
		},
	})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedFiles | packages.NeedCompiledGoFiles |
		packages.NeedSyntax | packages.NeedDeps | packages.NeedTypes |
		packages.LoadMode(packagesinternal.TypecheckCgo)

	initial, err := packages.Load(exported.Config, "golang.org/fake/cgo")
	if err != nil {
		t.Fatal(err)
	}
	pkg := initial[0]
	if len(pkg.Errors) != 0 {
		t.Fatalf("package has errors: %v", pkg.Errors)
	}

	expos := pkg.Types.Scope().Lookup("Example").Pos()
	fname := pkg.Fset.File(expos).Name()
	if !strings.HasSuffix(fname, "cgo.go") {
		t.Errorf("position for cgo package was loaded from %v, wanted cgo.go", fname)
	}
}

// TestIssue48226 ensures that when NeedSyntax is provided we do not nullify the
// Fset, which is needed to resolve the syntax tree element positions to files.
func TestIssue48226(t *testing.T) { testAllOrModulesParallel(t, testIssue48226) }
func testIssue48226(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{
		{
			Name: "golang.org/fake/syntax",
			Files: map[string]any{
				"syntax.go": `package test`,
			},
		},
	})
	defer exported.Cleanup()

	exported.Config.Mode = packages.NeedFiles | packages.NeedSyntax

	initial, err := packages.Load(exported.Config, "golang.org/fake/syntax")
	if err != nil {
		t.Fatal(err)
	}
	if len(initial) != 1 {
		t.Fatalf("expected 1 package, got %d", len(initial))
	}
	pkg := initial[0]

	if len(pkg.Errors) != 0 {
		t.Fatalf("package has errors: %v", pkg.Errors)
	}

	fname := pkg.Fset.File(pkg.Syntax[0].FileStart).Name()
	if filepath.Base(fname) != "syntax.go" {
		t.Errorf("expected the package declaration position "+
			"to resolve to \"syntax.go\", got %q instead", fname)
	}
}

func TestModule(t *testing.T) {
	testAllOrModulesParallel(t, testModule)
}
func testModule(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name:  "golang.org/fake",
		Files: map[string]any{"a/a.go": `package a`}}})
	exported.Config.Mode = packages.NeedModule
	rootDir := filepath.Dir(filepath.Dir(exported.File("golang.org/fake", "a/a.go")))

	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}

	if len(initial) != 1 {
		t.Fatal("want exactly one package, got ", initial)
	}
	a := initial[0]
	switch exported.Exporter.Name() {
	case "GOPATH":
		if a.Module != nil {
			t.Fatal("package.Module: want nil, got ", a.Module)
		}
	case "Modules":
		// Make sure Modules field is set, and spot check a few of its fields.
		if a.Module == nil {
			t.Fatal("package.Module: want non-nil, got nil")
		}
		if a.Module.Path != "golang.org/fake" {
			t.Fatalf("package.Module.Path: want \"golang.org/fake\", got %q", a.Module.Path)
		}
		if a.Module.GoMod != filepath.Join(rootDir, "go.mod") {
			t.Fatalf("package.Module.GoMod: want %q, got %q", filepath.Join(rootDir, "go.mod"), a.Module.GoMod)
		}
	default:
		t.Fatalf("Expected exporter to be GOPATH or Modules, got %v", exported.Exporter.Name())
	}
}

func TestExternal_NotHandled(t *testing.T) {
	testAllOrModulesParallel(t, testExternal_NotHandled)
}
func testExternal_NotHandled(t *testing.T, exporter packagestest.Exporter) {
	skipIfShort(t, "builds and links fake driver binaries")
	testenv.NeedsGoBuild(t)

	tempdir, err := os.MkdirTemp("", "testexternal")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tempdir)

	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a`,
			"empty_driver/main.go": `package main

import (
	"fmt"
	"io"
	"os"
)

func main() {
	io.ReadAll(os.Stdin)
	fmt.Println("{}")
}
`,
			"nothandled_driver/main.go": `package main

import (
	"fmt"
	"io"
	"os"
)

func main() {
	io.ReadAll(os.Stdin)
	fmt.Println("{\"NotHandled\": true}")
}
`,
		}}})
	baseEnv := exported.Config.Env

	// As a control, create a fake driver that always returns an empty response.
	emptyDriverPath := filepath.Join(tempdir, "empty_driver.exe") // Add .exe because Windows expects it.
	cmd := exec.Command("go", "build", "-o", emptyDriverPath, "golang.org/fake/empty_driver")
	cmd.Env = baseEnv
	cmd.Dir = exported.Config.Dir
	if b, err := cmd.CombinedOutput(); err != nil {
		t.Log(string(b))
		t.Fatal(err)
	}

	exported.Config.Env = append(slices.Clone(baseEnv), "GOPACKAGESDRIVER="+emptyDriverPath)
	initial, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}

	if len(initial) != 0 {
		t.Errorf("package.Load with empty driver: want [], got %v", initial)
	}

	// Create a fake driver that always returns a NotHandled response.
	notHandledDriverPath := filepath.Join(tempdir, "nothandled_driver.exe")
	cmd = exec.Command("go", "build", "-o", notHandledDriverPath, "golang.org/fake/nothandled_driver")
	cmd.Env = baseEnv
	cmd.Dir = exported.Config.Dir
	if b, err := cmd.CombinedOutput(); err != nil {
		t.Log(string(b))
		t.Fatal(err)
	}

	exported.Config.Env = append(slices.Clone(baseEnv), "GOPACKAGESDRIVER="+notHandledDriverPath)
	initial, err = packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}

	if len(initial) != 1 || initial[0].PkgPath != "golang.org/fake/a" {
		t.Errorf("package.Load: want [golang.org/fake/a], got %v", initial)
	}
}

func TestInvalidPackageName(t *testing.T) {
	testAllOrModulesParallel(t, testInvalidPackageName)
}

func testInvalidPackageName(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"main.go": `package default

func main() {
}
`,
		},
	}})
	defer exported.Cleanup()

	initial, err := packages.Load(exported.Config, "golang.org/fake")
	if err != nil {
		t.Fatal(err)
	}
	pkg := initial[0]
	if len(pkg.CompiledGoFiles) != 1 {
		t.Fatalf("expected 1 Go file in package %s, got %v", pkg.ID, len(pkg.CompiledGoFiles))
	}
}

func TestEmptyEnvironment(t *testing.T) {
	t.Parallel()

	cfg := &packages.Config{
		Env: []string{"FOO=BAR"},
	}
	_, err := packages.Load(cfg, "fmt")
	if err == nil {
		t.Fatal("Load with explicitly empty environment should fail")
	}
}

func TestPackageLoadSingleFile(t *testing.T) {
	testenv.NeedsTool(t, "go")

	tmp, err := os.MkdirTemp("", "a")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmp)

	filename := filepath.Join(tmp, "a.go")

	if err := os.WriteFile(filename, []byte(`package main; func main() { println("hello world") }`), 0775); err != nil {
		t.Fatal(err)
	}

	pkgs, err := packages.Load(&packages.Config{Mode: packages.LoadSyntax, Dir: tmp}, "file="+filename)
	if err != nil {
		t.Fatalf("could not load package: %v", err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("expected one package to be loaded, got %d", len(pkgs))
	}
	if len(pkgs[0].CompiledGoFiles) != 1 || pkgs[0].CompiledGoFiles[0] != filename {
		t.Fatalf("expected one compiled go file (%q), got %v", filename, pkgs[0].CompiledGoFiles)
	}
}

func errorMessages(errors []packages.Error) []string {
	var msgs []string
	for _, err := range errors {
		msgs = append(msgs, err.Msg)
	}
	return msgs
}

func srcs(p *packages.Package) []string {
	var files []string
	files = append(files, p.GoFiles...)
	files = append(files, p.OtherFiles...)
	files = append(files, p.EmbedFiles...)
	return cleanPaths(files)
}

// cleanPaths attempts to reduce path names to stable forms
func cleanPaths(paths []string) []string {
	result := make([]string, len(paths))
	for i, src := range paths {
		// If the source file doesn't have an extension like .go or .s,
		// it comes from GOCACHE. The names there aren't predictable.
		name := filepath.Base(src)
		if !strings.Contains(name, ".") {
			result[i] = fmt.Sprintf("%d.go", i) // make cache names predictable
		} else {
			result[i] = name
		}
	}
	return result
}

// importGraph returns the import graph as a user-friendly string,
// and a map containing all packages keyed by ID.
func importGraph(initial []*packages.Package) (string, map[string]*packages.Package) {
	out := new(bytes.Buffer)

	initialSet := make(map[*packages.Package]bool)
	for _, p := range initial {
		initialSet[p] = true
	}

	// We can't use Visit or Postorder because we need to prune
	// the traversal of specific edges, not just nodes.
	var nodes, edges []string
	res := make(map[string]*packages.Package)
	seen := make(map[*packages.Package]bool)
	var visit func(p *packages.Package)
	visit = func(p *packages.Package) {
		if !seen[p] {
			seen[p] = true
			if res[p.ID] != nil {
				panic("duplicate ID: " + p.ID)
			}
			res[p.ID] = p

			star := ' ' // mark initial packages with a star
			if initialSet[p] {
				star = '*'
			}
			nodes = append(nodes, fmt.Sprintf("%c %s", star, p.ID))

			// To avoid a lot of noise,
			// we prune uninteresting dependencies of testmain packages,
			// which we identify by this import:
			isTestMain := p.Imports["testing/internal/testdeps"] != nil

			for _, imp := range p.Imports {
				if isTestMain {
					switch imp.ID {
					case "os", "reflect", "testing", "testing/internal/testdeps":
						continue
					}
				}
				// math/bits took on a dependency on unsafe in 1.12, which breaks some
				// tests. As a short term hack, prune that edge.
				// ditto for ("errors", "internal/reflectlite") in 1.13.
				// TODO(matloob): think of a cleaner solution, or remove math/bits from the test.
				if p.ID == "math/bits" && imp.ID == "unsafe" {
					continue
				}
				edges = append(edges, fmt.Sprintf("%s -> %s", p, imp))
				visit(imp)
			}
		}
	}
	for _, p := range initial {
		visit(p)
	}

	// Sort, ignoring leading optional star prefix.
	sort.Slice(nodes, func(i, j int) bool { return nodes[i][2:] < nodes[j][2:] })
	for _, node := range nodes {
		fmt.Fprintf(out, "%s\n", node)
	}

	sort.Strings(edges)
	for _, edge := range edges {
		fmt.Fprintf(out, "  %s\n", edge)
	}

	return out.String(), res
}

func constant(p *packages.Package, name string) *types.Const {
	if p == nil || p.Types == nil {
		return nil
	}
	c := p.Types.Scope().Lookup(name)
	if c == nil {
		return nil
	}
	return c.(*types.Const)
}

func TestExportFile(t *testing.T) {
	// This used to trigger the log.Fatal in loadFromExportData.
	// See go.dev/issue/45584.
	cfg := new(packages.Config)
	cfg.Mode = packages.NeedTypes
	packages.Load(cfg, "fmt")
}

// TestLoadEitherSucceedsOrFails is an attempt to reproduce a sporadic
// failure observed on the Android emu builders in which Load would
// return an empty list of packages but no error. We don't expect
// packages.Load to succeed on that platform, and testenv.NeedsGoBuild
// would ordinarily suppress the attempt if called early. But
// regardless of whether the 'go' command is functional, Load should
// never return an empty set of packages but no error.
func TestLoadEitherSucceedsOrFails(t *testing.T) {
	const src = `package p`
	dir := t.TempDir()
	cfg := &packages.Config{
		Dir:  dir,
		Mode: packages.LoadSyntax,
		Overlay: map[string][]byte{
			filepath.Join(dir, "p.go"): []byte(src),
		},
	}
	initial, err := packages.Load(cfg, "./p.go")
	if err != nil {
		// If Load failed because it needed 'go' and the
		// platform doesn't have it, silently skip the test.
		testenv.NeedsGoBuild(t)

		// Otherwise, it's a real failure.
		t.Fatal(err)
	}

	// If Load returned without error,
	// it had better give us error-free packages.
	if packages.PrintErrors(initial) > 0 {
		t.Errorf("packages contain errors")
	}

	// If Load returned without error,
	// it had better give us the correct number packages.
	if len(initial) != 1 {
		t.Errorf("Load returned %d packages (want 1) and no error", len(initial))
	}
}

// TestLoadOverlayGoMod ensures that overlays containing go.mod files
// are effective for all 'go list' calls made by go/packages (#67644).
func TestLoadOverlayGoMod(t *testing.T) {
	testenv.NeedsGoBuild(t)

	cwd, _ := os.Getwd()

	// This test ensures that the overlaid go.mod file is seen by
	// all runs of 'go list', in particular the early run that
	// enumerates the modules: if the go.mod file were absent,
	// it would ascend to the parent directory (x/tools) and
	// then (falsely) report inconsistent vendoring.
	//
	// (Ideally the testdata would be constructed from nothing
	// rather than rely on the go/packages source tree, but it is
	// turned out to a bigger project than bargained for.)
	cfg := &packages.Config{
		Mode: packages.LoadSyntax,
		Overlay: map[string][]byte{
			filepath.Join(cwd, "go.mod"): []byte("module example.com\ngo 1.0"),
		},
		Env: append(os.Environ(), "GOFLAGS=-mod=vendor", "GOWORK=off"),
	}

	pkgs, err := packages.Load(cfg, "./testdata")
	if err != nil {
		t.Fatal(err) // (would previously fail here with "inconsistent vendoring")
	}
	got := fmt.Sprint(pkgs)
	want := `[./testdata]`
	if got != want {
		t.Errorf("Load: got %s, want %v", got, want)
	}
}

func overlayFS(overlay map[string][]byte) fstest.MapFS {
	fs := make(fstest.MapFS)
	for name, data := range overlay {
		fs[name] = &fstest.MapFile{Data: data}
	}
	return fs
}

// TestIssue69606a tests when tools in $GOROOT/pkg/tool/$GOOS_$GOARCH are missing,
// Load should return an error.
func TestIssue69606a(t *testing.T) {
	testenv.NeedsTool(t, "go")
	overlay := overlayFS(map[string][]byte{
		"io/io.go":         []byte("package io"),
		"unsafe/unsafe.go": []byte("package unsafe"),
	})
	goroot := testfiles.CopyToTmp(t, overlay)

	t.Logf("custom GOROOT: %s", goroot)

	// load the std packages under a custom GOROOT
	_, err := packages.Load(&packages.Config{
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedImports |
			packages.NeedTypes,
		Env: append(
			os.Environ(),
			"GO111MODULES=on",
			"GOPATH=",
			"GOWORK=off",
			"GOPROXY=off",
			fmt.Sprintf("GOROOT=%s", goroot)),
	}, "std")

	if err == nil {
		t.Fatal("Expected to get an error because missing tool 'compile' but got a nil error")
	}
}

// TestIssue69606b tests when loading std from a fake goroot without a unsafe package,
// Load should return an error.
func TestIssue69606b(t *testing.T) {
	testenv.NeedsTool(t, "go")
	overlay := overlayFS(map[string][]byte{
		"io/io.go": []byte("package io"),
	})
	goroot := testfiles.CopyToTmp(t, overlay)

	t.Logf("custom GOROOT: %s", goroot)

	// load the std packages under a custom GOROOT
	_, err := packages.Load(&packages.Config{
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedImports |
			packages.NeedTypes,
		Env: append(
			os.Environ(),
			"GO111MODULES=on",
			"GOPATH=",
			"GOWORK=off",
			"GOPROXY=off",
			fmt.Sprintf("GOROOT=%s", goroot)),
	}, "std")

	if err == nil {
		t.Fatal("Expected to get an error because missing unsafe package but got a nil error")
	}
}

// TestIssue70394 tests materializing an alias type defined in a package (m/a)
// in another package (m/b) where the types for m/b are coming from the compiler,
// e.g. `go list -compiled=true ... m/b`.
func TestIssue70394(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)
	testenv.NeedsTool(t, "go") // requires go list.
	testenv.NeedsGoBuild(t)    // requires the compiler for export data.

	dir := t.TempDir()
	overlay := map[string][]byte{
		filepath.Join(dir, "go.mod"): []byte("module m"), // go version of the module does not matter.
		filepath.Join(dir, "a/a.go"): []byte(`package a; type A = int32`),
		filepath.Join(dir, "b/b.go"): []byte(`package b; import "m/a"; var V a.A`),
	}
	cfg := &packages.Config{
		Dir:     dir,
		Mode:    packages.NeedTypes, // just NeedsTypes allows for loading export data.
		Overlay: overlay,
		Env:     append(os.Environ(), "GOFLAGS=-mod=vendor", "GOWORK=off"),
	}
	pkgs, err := packages.Load(cfg, "m/b")
	if err != nil {
		t.Fatal(err)
	}
	if errs := packages.PrintErrors(pkgs); errs > 0 {
		t.Fatalf("Got %d errors while loading packages.", errs)
	}
	if len(pkgs) != 1 {
		t.Fatalf("Loaded %d packages. expected 1", len(pkgs))
	}

	pkg := pkgs[0]
	scope := pkg.Types.Scope()
	obj := scope.Lookup("V")
	if obj == nil {
		t.Fatalf("Failed to find object %q in package %q", "V", pkg)
	}
	if _, ok := obj.Type().(*types.Alias); !ok {
		t.Errorf("Object %q has type %q. expected an alias", obj, obj.Type())
	}
}

// TestLoadTypesInfoWithoutSyntaxOrTypes tests when NeedTypesInfo was set and NeedSyntax & NeedTypes were not,
// Load should include the TypesInfo of packages properly
func TestLoadTypesInfoWithoutSyntaxOrTypes(t *testing.T) {
	testAllOrModulesParallel(t, testLoadTypesInfoWithoutSyntaxOrTypes)
}

func testLoadTypesInfoWithoutSyntaxOrTypes(t *testing.T, exporter packagestest.Exporter) {
	exported := packagestest.Export(t, exporter, []packagestest.Module{{
		Name: "golang.org/fake",
		Files: map[string]any{
			"a/a.go": `package a;

func foo() int {
	i := 0
	s := "abc"
	return i + len(s)
}
`,
		}}})
	defer exported.Cleanup()
	exported.Config.Mode = packages.NeedTypesInfo

	pkgs, err := packages.Load(exported.Config, "golang.org/fake/a")
	if err != nil {
		t.Fatal(err)
	}

	// check if types info is present
	if pkgs[0].TypesInfo == nil {
		t.Errorf("expected types info to be present but got nil")
	}
}

// TestDirAndForTest tests the new fields added as part of golang/go#38445.
func TestDirAndForTest(t *testing.T) {
	testenv.NeedsGoPackages(t)

	dir := writeTree(t, `
-- go.mod --
module example.com

go 1.18

-- a/a.go --
package a

func Foo() int { return 1 }

-- a/a_test.go --
package a

func Bar() int { return 2 }

-- a/a_x_test.go --
package a_test

import (
	"example.com/a"
	"example.com/b"
)

func _() {
	if got := a.Foo() + a.Bar() + b.Baz(); got != 6 {
		panic("whoops")
	}
}

-- b/b.go --
package b

import "example.com/a"

func Baz() int { return 3 }

func Foo() int { return a.Foo() }
`)

	pkgs, err := packages.Load(&packages.Config{
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedForTest |
			packages.NeedImports,
		Dir:   dir,
		Tests: true,
	}, "./...")
	if err != nil {
		t.Fatal(err)
	}
	type result struct{ Dir, ForTest string }
	got := make(map[string]result)
	for pkg := range packages.Postorder(pkgs) {
		if !packagepath.IsStdPackage(pkg.PkgPath) {
			rel, err := filepath.Rel(dir, pkg.Dir)
			if err != nil {
				t.Errorf("Rel(%q, %q) failed: %v", dir, pkg.Dir, err)
				continue
			}
			got[pkg.ID] = result{
				Dir:     rel,
				ForTest: pkg.ForTest,
			}
		}
	}
	want := map[string]result{
		"example.com/a":                           {"a", ""},
		"example.com/a.test":                      {"a", ""},
		"example.com/a [example.com/a.test]":      {"a", "example.com/a"}, // test variant
		"example.com/a_test [example.com/a.test]": {"a", "example.com/a"}, // x_test
		"example.com/b [example.com/a.test]":      {"b", "example.com/a"}, // intermediate test variant
		"example.com/b":                           {"b", ""},
	}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("Load returned mismatching ForTest fields (ID->result -want +got):\n%s", diff)
	}
	t.Logf("Packages: %+v", pkgs)
}

// TestTarget tests the new field added as part of golang/go#38445.
// The test uses GOPATH mode because non-main packages don't usually
// have install targets in module mode.
func TestTarget(t *testing.T) {
	testenv.NeedsGoPackages(t)

	dir := writeTree(t, `
-- gopath/src/a/a.go --
package a

func Foo() {}
-- gopath/src/b/b.go --
package main

import "a"

func main() {
	a.Foo()
}
`)
	gopath := filepath.Join(dir, "gopath")

	pkgs, err := packages.Load(&packages.Config{
		Mode: packages.NeedName | packages.NeedTarget,
		Env:  append(os.Environ(), "GOPATH="+gopath, "GO111MODULE=off"),
	}, filepath.Join(gopath, "src", "..."))
	if err != nil {
		t.Fatal(err)
	}
	var goexe string
	if runtime.GOOS == "windows" {
		goexe = ".exe"
	}
	want := map[string]string{
		"a": filepath.Join(gopath, "pkg", runtime.GOOS+"_"+runtime.GOARCH, "a.a"),
		"b": filepath.Join(gopath, "bin", "b"+goexe),
	}
	got := make(map[string]string)
	for pkg := range packages.Postorder(pkgs) {
		got[pkg.PkgPath] = pkg.Target
	}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("Load returned mismatching Target fields (pkgpath->target -want +got):\n%s", diff)
	}
	t.Logf("Packages: %+v", pkgs)
}

// TestMainPackagePathInModeTypes tests (*types.Package).Path() for
// main packages in mode NeedTypes, a regression test for #70742, a
// bug in cmd/compile's export data that caused them to appear as
// "main". (The PkgPath field was always correct.)
func TestMainPackagePathInModeTypes(t *testing.T) {
	testenv.NeedsGoPackages(t)

	cfg := &packages.Config{Mode: packages.NeedName | packages.NeedTypes}
	pkgs, err := packages.Load(cfg, "cmd/go")
	if err != nil {
		t.Fatal(err)
	}
	p := pkgs[0]
	if p.PkgPath != "cmd/go" ||
		p.Name != "main" ||
		p.Types.Path() != "cmd/go" ||
		p.Types.Name() != "main" {
		t.Errorf("PkgPath=%q Name=%q Types.Path=%q Types.Name=%q; want (cmd/go, main) both times)",
			p.PkgPath,
			p.Name,
			p.Types.Name(),
			p.Types.Path())
	}
}

func writeTree(t *testing.T, archive string) string {
	root := t.TempDir()

	for _, f := range txtar.Parse([]byte(archive)).Files {
		filename := filepath.Join(root, f.Name)
		if err := os.MkdirAll(filepath.Dir(filename), 0777); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filename, f.Data, 0666); err != nil {
			t.Fatal(err)
		}
	}
	return root
}

func TestLoadFileRelativePath(t *testing.T) {
	exported := packagestest.Export(t, packagestest.Modules, []packagestest.Module{
		{
			Name: "fake/pkg",
			Files: map[string]any{
				"pkg.go": "package pkg; type A int",
			},
		},
	})
	t.Cleanup(exported.Cleanup)

	exported.Config.Mode = packages.LoadSyntax
	pkgs, err := packages.Load(exported.Config, "file=pkg.go")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("len(pkgs) = %v; want = 1", len(pkgs))
	}
	if pkgs[0].ID != "fake/pkg" {
		t.Fatalf(`pkgs[0].Id = %q; want "fake/pkg"`, pkgs[0].ID)
	}
}

func TestLoad_populatesInfoMapsForUnsafePackage(t *testing.T) {
	testenv.NeedsGoPackages(t)

	pkgs, err := packages.Load(&packages.Config{Mode: packages.LoadAllSyntax}, "unsafe")
	if err != nil {
		t.Fatal(err)
	}
	info := pkgs[0].TypesInfo

	if info.Defs == nil ||
		info.Uses == nil ||
		info.Selections == nil ||
		info.Types == nil ||
		info.FileVersions == nil ||
		info.Implicits == nil ||
		info.Instances == nil ||
		info.Scopes == nil {
		t.Errorf("types.Info for package unsafe has one or more nil maps: %#v", *info)
	}
}


================================================
FILE: go/packages/stdlib_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages_test

import (
	"runtime"
	"testing"
	"time"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
)

// This test loads the metadata for the standard library,
func TestStdlibMetadata(t *testing.T) {
	testenv.NeedsGoPackages(t)

	runtime.GC()
	t0 := time.Now()
	var memstats runtime.MemStats
	runtime.ReadMemStats(&memstats)
	alloc := memstats.Alloc

	// Load, parse and type-check the program.
	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
	pkgs, err := packages.Load(cfg, "std")
	if err != nil {
		t.Fatalf("failed to load metadata: %v", err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		t.Fatal("there were errors loading standard library")
	}

	t1 := time.Now()
	runtime.GC()
	runtime.ReadMemStats(&memstats)
	runtime.KeepAlive(pkgs)

	t.Logf("Loaded %d packages", len(pkgs))
	numPkgs := len(pkgs)

	want := 150 // 186 on linux, 185 on windows.
	if numPkgs < want {
		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, want)
	}

	t.Log("GOMAXPROCS: ", runtime.GOMAXPROCS(0))
	t.Log("Metadata:   ", t1.Sub(t0))                          // ~800ms on 12 threads
	t.Log("#MB:        ", int64(memstats.Alloc-alloc)/1000000) // ~1MB
}

// BenchmarkNetHTTP measures the time to load/parse/typecheck the
// net/http package and all dependencies.
func BenchmarkNetHTTP(b *testing.B) {
	testenv.NeedsGoPackages(b)
	b.ReportAllocs()

	var bytes int64

	for i := range b.N {
		cfg := &packages.Config{Mode: packages.LoadAllSyntax}
		pkgs, err := packages.Load(cfg, "net/http")
		if err != nil {
			b.Fatalf("failed to load metadata: %v", err)
		}
		if packages.PrintErrors(pkgs) > 0 {
			b.Fatal("there were errors loading net/http")
		}

		if i == 0 {
			for pkg := range packages.Postorder(pkgs) {
				for _, f := range pkg.Syntax {
					bytes += int64(f.FileEnd - f.FileStart)
				}
			}
		}
	}

	b.SetBytes(bytes) // total source bytes
}


================================================
FILE: go/packages/visit.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packages

import (
	"cmp"
	"fmt"
	"iter"
	"os"
	"slices"
)

// Visit visits all the packages in the import graph whose roots are
// pkgs, calling the optional pre function the first time each package
// is encountered (preorder), and the optional post function after a
// package's dependencies have been visited (postorder).
// The boolean result of pre(pkg) determines whether
// the imports of package pkg are visited.
//
// Example:
//
//	pkgs, err := Load(...)
//	if err != nil { ... }
//	Visit(pkgs, nil, func(pkg *Package) {
//		log.Println(pkg)
//	})
//
// In most cases, it is more convenient to use [Postorder]:
//
//	for pkg := range Postorder(pkgs) {
//		log.Println(pkg)
//	}
func Visit(pkgs []*Package, pre func(*Package) bool, post func(*Package)) {
	seen := make(map[*Package]bool)
	var visit func(*Package)
	visit = func(pkg *Package) {
		if !seen[pkg] {
			seen[pkg] = true

			if pre == nil || pre(pkg) {
				for _, imp := range sorted(pkg.Imports) { // for determinism
					visit(imp)
				}
			}

			if post != nil {
				post(pkg)
			}
		}
	}
	for _, pkg := range pkgs {
		visit(pkg)
	}
}

// PrintErrors prints to os.Stderr the accumulated errors of all
// packages in the import graph rooted at pkgs, dependencies first.
// PrintErrors returns the number of errors printed.
func PrintErrors(pkgs []*Package) int {
	var n int
	errModules := make(map[*Module]bool)
	for pkg := range Postorder(pkgs) {
		for _, err := range pkg.Errors {
			fmt.Fprintln(os.Stderr, err)
			n++
		}

		// Print pkg.Module.Error once if present.
		mod := pkg.Module
		if mod != nil && mod.Error != nil && !errModules[mod] {
			errModules[mod] = true
			fmt.Fprintln(os.Stderr, mod.Error.Err)
			n++
		}
	}
	return n
}

// Postorder returns an iterator over the packages in
// the import graph whose roots are pkg.
// Packages are enumerated in dependencies-first order.
func Postorder(pkgs []*Package) iter.Seq[*Package] {
	return func(yield func(*Package) bool) {
		seen := make(map[*Package]bool)
		var visit func(*Package) bool
		visit = func(pkg *Package) bool {
			if !seen[pkg] {
				seen[pkg] = true
				for _, imp := range sorted(pkg.Imports) { // for determinism
					if !visit(imp) {
						return false
					}
				}
				if !yield(pkg) {
					return false
				}
			}
			return true
		}
		for _, pkg := range pkgs {
			if !visit(pkg) {
				break
			}
		}
	}
}

// -- copied from golang.org.x/tools/gopls/internal/util/moremaps --

// sorted returns an iterator over the entries of m in key order.
func sorted[M ~map[K]V, K cmp.Ordered, V any](m M) iter.Seq2[K, V] {
	// TODO(adonovan): use maps.Sorted if proposal #68598 is accepted.
	return func(yield func(K, V) bool) {
		keys := keySlice(m)
		slices.Sort(keys)
		for _, k := range keys {
			if !yield(k, m[k]) {
				break
			}
		}
	}
}

// KeySlice returns the keys of the map M, like slices.Collect(maps.Keys(m)).
func keySlice[M ~map[K]V, K comparable, V any](m M) []K {
	r := make([]K, 0, len(m))
	for k := range m {
		r = append(r, k)
	}
	return r
}


================================================
FILE: go/ssa/TODO
================================================
-*- text -*-

SSA Generics to-do list
===========================

DOCUMENTATION:
- Read me for internals

TYPE PARAMETERIZED GENERIC FUNCTIONS:
- sanity.go updates.
- Check source functions going to generics.
- Tests, tests, tests...

USAGE:
- Back fill users for handling ssa.InstantiateGenerics being off.



================================================
FILE: go/ssa/block.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import "fmt"

// This file implements the BasicBlock type.

// addEdge adds a control-flow graph edge from from to to.
func addEdge(from, to *BasicBlock) {
	from.Succs = append(from.Succs, to)
	to.Preds = append(to.Preds, from)
}

// Parent returns the function that contains block b.
func (b *BasicBlock) Parent() *Function { return b.parent }

// String returns a human-readable label of this block.
// It is not guaranteed unique within the function.
func (b *BasicBlock) String() string {
	return fmt.Sprintf("%d", b.Index)
}

// emit appends an instruction to the current basic block.
// If the instruction defines a Value, it is returned.
func (b *BasicBlock) emit(i Instruction) Value {
	i.setBlock(b)
	b.Instrs = append(b.Instrs, i)
	v, _ := i.(Value)
	return v
}

// predIndex returns the i such that b.Preds[i] == c or panics if
// there is none.
func (b *BasicBlock) predIndex(c *BasicBlock) int {
	for i, pred := range b.Preds {
		if pred == c {
			return i
		}
	}
	panic(fmt.Sprintf("no edge %s -> %s", c, b))
}

// hasPhi returns true if b.Instrs contains φ-nodes.
func (b *BasicBlock) hasPhi() bool {
	_, ok := b.Instrs[0].(*Phi)
	return ok
}

// phis returns the prefix of b.Instrs containing all the block's φ-nodes.
func (b *BasicBlock) phis() []Instruction {
	for i, instr := range b.Instrs {
		if _, ok := instr.(*Phi); !ok {
			return b.Instrs[:i]
		}
	}
	return nil // unreachable in well-formed blocks
}

// replacePred replaces all occurrences of p in b's predecessor list with q.
// Ordinarily there should be at most one.
func (b *BasicBlock) replacePred(p, q *BasicBlock) {
	for i, pred := range b.Preds {
		if pred == p {
			b.Preds[i] = q
		}
	}
}

// replaceSucc replaces all occurrences of p in b's successor list with q.
// Ordinarily there should be at most one.
func (b *BasicBlock) replaceSucc(p, q *BasicBlock) {
	for i, succ := range b.Succs {
		if succ == p {
			b.Succs[i] = q
		}
	}
}

// removePred removes all occurrences of p in b's
// predecessor list and φ-nodes.
// Ordinarily there should be at most one.
func (b *BasicBlock) removePred(p *BasicBlock) {
	phis := b.phis()

	// We must preserve edge order for φ-nodes.
	j := 0
	for i, pred := range b.Preds {
		if pred != p {
			b.Preds[j] = b.Preds[i]
			// Strike out φ-edge too.
			for _, instr := range phis {
				phi := instr.(*Phi)
				phi.Edges[j] = phi.Edges[i]
			}
			j++
		}
	}
	// Nil out b.Preds[j:] and φ-edges[j:] to aid GC.
	for i := j; i < len(b.Preds); i++ {
		b.Preds[i] = nil
		for _, instr := range phis {
			instr.(*Phi).Edges[i] = nil
		}
	}
	b.Preds = b.Preds[:j]
	for _, instr := range phis {
		phi := instr.(*Phi)
		phi.Edges = phi.Edges[:j]
	}
}


================================================
FILE: go/ssa/blockopt.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// Simple block optimizations to simplify the control flow graph.

// TODO(adonovan): opt: instead of creating several "unreachable" blocks
// per function in the Builder, reuse a single one (e.g. at Blocks[1])
// to reduce garbage.

import (
	"fmt"
	"os"
)

// If true, perform sanity checking and show progress at each
// successive iteration of optimizeBlocks.  Very verbose.
const debugBlockOpt = false

// markReachable sets Index=-1 for all blocks reachable from b.
func markReachable(b *BasicBlock) {
	b.Index = -1
	for _, succ := range b.Succs {
		if succ.Index == 0 {
			markReachable(succ)
		}
	}
}

// deleteUnreachableBlocks marks all reachable blocks of f and
// eliminates (nils) all others, including possibly cyclic subgraphs.
func deleteUnreachableBlocks(f *Function) {
	const white, black = 0, -1
	// We borrow b.Index temporarily as the mark bit.
	for _, b := range f.Blocks {
		b.Index = white
	}
	markReachable(f.Blocks[0])
	if f.Recover != nil {
		markReachable(f.Recover)
	}
	for i, b := range f.Blocks {
		if b.Index == white {
			for _, c := range b.Succs {
				if c.Index == black {
					c.removePred(b) // delete white->black edge
				}
			}
			if debugBlockOpt {
				fmt.Fprintln(os.Stderr, "unreachable", b)
			}
			f.Blocks[i] = nil // delete b
		}
	}
	f.removeNilBlocks()
}

// jumpThreading attempts to apply simple jump-threading to block b,
// in which a->b->c become a->c if b is just a Jump.
// The result is true if the optimization was applied.
func jumpThreading(f *Function, b *BasicBlock) bool {
	if b.Index == 0 {
		return false // don't apply to entry block
	}
	if b.Instrs == nil {
		return false
	}
	if _, ok := b.Instrs[0].(*Jump); !ok {
		return false // not just a jump
	}
	c := b.Succs[0]
	if c == b {
		return false // don't apply to degenerate jump-to-self.
	}
	if c.hasPhi() {
		return false // not sound without more effort
	}
	for j, a := range b.Preds {
		a.replaceSucc(b, c)

		// If a now has two edges to c, replace its degenerate If by Jump.
		if len(a.Succs) == 2 && a.Succs[0] == c && a.Succs[1] == c {
			jump := new(Jump)
			jump.setBlock(a)
			a.Instrs[len(a.Instrs)-1] = jump
			a.Succs = a.Succs[:1]
			c.removePred(b)
		} else {
			if j == 0 {
				c.replacePred(b, a)
			} else {
				c.Preds = append(c.Preds, a)
			}
		}

		if debugBlockOpt {
			fmt.Fprintln(os.Stderr, "jumpThreading", a, b, c)
		}
	}
	f.Blocks[b.Index] = nil // delete b
	return true
}

// fuseBlocks attempts to apply the block fusion optimization to block
// a, in which a->b becomes ab if len(a.Succs)==len(b.Preds)==1.
// The result is true if the optimization was applied.
func fuseBlocks(f *Function, a *BasicBlock) bool {
	if len(a.Succs) != 1 {
		return false
	}
	b := a.Succs[0]
	if len(b.Preds) != 1 {
		return false
	}

	// Degenerate &&/|| ops may result in a straight-line CFG
	// containing φ-nodes. (Ideally we'd replace such them with
	// their sole operand but that requires Referrers, built later.)
	if b.hasPhi() {
		return false // not sound without further effort
	}

	// Eliminate jump at end of A, then copy all of B across.
	a.Instrs = append(a.Instrs[:len(a.Instrs)-1], b.Instrs...)
	for _, instr := range b.Instrs {
		instr.setBlock(a)
	}

	// A inherits B's successors
	a.Succs = append(a.succs2[:0], b.Succs...)

	// Fix up Preds links of all successors of B.
	for _, c := range b.Succs {
		c.replacePred(b, a)
	}

	if debugBlockOpt {
		fmt.Fprintln(os.Stderr, "fuseBlocks", a, b)
	}

	f.Blocks[b.Index] = nil // delete b
	return true
}

// optimizeBlocks() performs some simple block optimizations on a
// completed function: dead block elimination, block fusion, jump
// threading.
func optimizeBlocks(f *Function) {
	deleteUnreachableBlocks(f)

	// Loop until no further progress.
	changed := true
	for changed {
		changed = false

		if debugBlockOpt {
			f.WriteTo(os.Stderr)
			mustSanityCheck(f, nil)
		}

		for _, b := range f.Blocks {
			// f.Blocks will temporarily contain nils to indicate
			// deleted blocks; we remove them at the end.
			if b == nil {
				continue
			}

			// Fuse blocks.  b->c becomes bc.
			if fuseBlocks(f, b) {
				changed = true
			}

			// a->b->c becomes a->c if b contains only a Jump.
			if jumpThreading(f, b) {
				changed = true
				continue // (b was disconnected)
			}
		}
	}
	f.removeNilBlocks()
}


================================================
FILE: go/ssa/builder.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines the builder, which builds SSA-form IR for function bodies.
//
// SSA construction has two phases, "create" and "build". First, one
// or more packages are created in any order by a sequence of calls to
// CreatePackage, either from syntax or from mere type information.
// Each created package has a complete set of Members (const, var,
// type, func) that can be accessed through methods like
// Program.FuncValue.
//
// It is not necessary to call CreatePackage for all dependencies of
// each syntax package, only for its direct imports. (In future
// perhaps even this restriction may be lifted.)
//
// Second, packages created from syntax are built, by one or more
// calls to Package.Build, which may be concurrent; or by a call to
// Program.Build, which builds all packages in parallel. Building
// traverses the type-annotated syntax tree of each function body and
// creates SSA-form IR, a control-flow graph of instructions,
// populating fields such as Function.Body, .Params, and others.
//
// Building may create additional methods, including:
// - wrapper methods (e.g. for embedding, or implicit &recv)
// - bound method closures (e.g. for use(recv.f))
// - thunks (e.g. for use(I.f) or use(T.f))
// - generic instances (e.g. to produce f[int] from f[any]).
// As these methods are created, they are added to the build queue,
// and then processed in turn, until a fixed point is reached,
// Since these methods might belong to packages that were not
// created (by a call to CreatePackage), their Pkg field is unset.
//
// Instances of generic functions may be either instantiated (f[int]
// is a copy of f[T] with substitutions) or wrapped (f[int] delegates
// to f[T]), depending on the availability of generic syntax and the
// InstantiateGenerics mode flag.
//
// Each package has an initializer function named "init" that calls
// the initializer functions of each direct import, computes and
// assigns the initial value of each global variable, and calls each
// source-level function named "init". (These generate SSA functions
// named "init#1", "init#2", etc.)
//
// Runtime types
//
// Each MakeInterface operation is a conversion from a non-interface
// type to an interface type. The semantics of this operation requires
// a runtime type descriptor, which is the type portion of an
// interface, and the value abstracted by reflect.Type.
//
// The program accumulates all non-parameterized types that are
// encountered as MakeInterface operands, along with all types that
// may be derived from them using reflection. This set is available as
// Program.RuntimeTypes, and the methods of these types may be
// reachable via interface calls or reflection even if they are never
// referenced from the SSA IR. (In practice, algorithms such as RTA
// that compute reachability from package main perform their own
// tracking of runtime types at a finer grain, so this feature is not
// very useful.)
//
// Function literals
//
// Anonymous functions must be built as soon as they are encountered,
// as it may affect locals of the enclosing function, but they are not
// marked 'built' until the end of the outermost enclosing function.
// (Among other things, this causes them to be logged in top-down order.)
//
// The Function.build fields determines the algorithm for building the
// function body. It is cleared to mark that building is complete.

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"os"
	"runtime"
	"sync"

	"slices"

	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/versions"
)

type opaqueType struct{ name string }

func (t *opaqueType) String() string         { return t.name }
func (t *opaqueType) Underlying() types.Type { return t }

var (
	varOk    = newVar("ok", tBool)
	varIndex = newVar("index", tInt)

	// Type constants.
	tBool       = types.Typ[types.Bool]
	tByte       = types.Typ[types.Byte]
	tInt        = types.Typ[types.Int]
	tInvalid    = types.Typ[types.Invalid]
	tString     = types.Typ[types.String]
	tUntypedNil = types.Typ[types.UntypedNil]

	tRangeIter  = &opaqueType{"iter"}                         // the type of all "range" iterators
	tDeferStack = types.NewPointer(&opaqueType{"deferStack"}) // the type of a "deferStack" from ssa:deferstack()
	tEface      = types.NewInterfaceType(nil, nil).Complete()

	// SSA Value constants.
	vZero     = intConst(0)
	vOne      = intConst(1)
	vTrue     = NewConst(constant.MakeBool(true), tBool)
	vFalse    = NewConst(constant.MakeBool(false), tBool)
	vNoReturn = NewConst(constant.MakeString("noreturn"), tString)

	jReady = intConst(0)  // range-over-func jump is READY
	jBusy  = intConst(-1) // range-over-func jump is BUSY
	jDone  = intConst(-2) // range-over-func jump is DONE

	// The ssa:deferstack intrinsic returns the current function's defer stack.
	vDeferStack = &Builtin{
		name: "ssa:deferstack",
		sig:  types.NewSignatureType(nil, nil, nil, nil, types.NewTuple(anonVar(tDeferStack)), false),
	}
)

// builder holds state associated with the package currently being built.
// Its methods contain all the logic for AST-to-SSA conversion.
//
// All Functions belong to the same Program.
//
// builders are not thread-safe.
type builder struct {
	fns []*Function // Functions that have finished their CREATE phases.

	finished int // finished is the length of the prefix of fns containing built functions.

	// The task of building shared functions within the builder.
	// Shared functions are ones the builder may either create or lookup.
	// These may be built by other builders in parallel.
	// The task is done when the builder has finished iterating, and it
	// waits for all shared functions to finish building.
	// nil implies there are no hared functions to wait on.
	buildshared *task
}

// shared is done when the builder has built all of the
// enqueued functions to a fixed-point.
func (b *builder) shared() *task {
	if b.buildshared == nil { // lazily-initialize
		b.buildshared = &task{done: make(chan unit)}
	}
	return b.buildshared
}

// enqueue fn to be built by the builder.
func (b *builder) enqueue(fn *Function) {
	b.fns = append(b.fns, fn)
}

// waitForSharedFunction indicates that the builder should wait until
// the potentially shared function fn has finished building.
//
// This should include any functions that may be built by other
// builders.
func (b *builder) waitForSharedFunction(fn *Function) {
	if fn.buildshared != nil { // maybe need to wait?
		s := b.shared()
		s.addEdge(fn.buildshared)
	}
}

// cond emits to fn code to evaluate boolean condition e and jump
// to t or f depending on its value, performing various simplifications.
//
// Postcondition: fn.currentBlock is nil.
func (b *builder) cond(fn *Function, e ast.Expr, t, f *BasicBlock) {
	switch e := e.(type) {
	case *ast.ParenExpr:
		b.cond(fn, e.X, t, f)
		return

	case *ast.BinaryExpr:
		switch e.Op {
		case token.LAND:
			ltrue := fn.newBasicBlock("cond.true")
			b.cond(fn, e.X, ltrue, f)
			fn.currentBlock = ltrue
			b.cond(fn, e.Y, t, f)
			return

		case token.LOR:
			lfalse := fn.newBasicBlock("cond.false")
			b.cond(fn, e.X, t, lfalse)
			fn.currentBlock = lfalse
			b.cond(fn, e.Y, t, f)
			return
		}

	case *ast.UnaryExpr:
		if e.Op == token.NOT {
			b.cond(fn, e.X, f, t)
			return
		}
	}

	// A traditional compiler would simplify "if false" (etc) here
	// but we do not, for better fidelity to the source code.
	//
	// The value of a constant condition may be platform-specific,
	// and may cause blocks that are reachable in some configuration
	// to be hidden from subsequent analyses such as bug-finding tools.
	emitIf(fn, b.expr(fn, e), t, f)
}

// logicalBinop emits code to fn to evaluate e, a &&- or
// ||-expression whose reified boolean value is wanted.
// The value is returned.
func (b *builder) logicalBinop(fn *Function, e *ast.BinaryExpr) Value {
	rhs := fn.newBasicBlock("binop.rhs")
	done := fn.newBasicBlock("binop.done")

	// T(e) = T(e.X) = T(e.Y) after untyped constants have been
	// eliminated.
	// TODO(adonovan): not true; MyBool==MyBool yields UntypedBool.
	t := fn.typeOf(e)

	var short Value // value of the short-circuit path
	switch e.Op {
	case token.LAND:
		b.cond(fn, e.X, rhs, done)
		short = NewConst(constant.MakeBool(false), t)

	case token.LOR:
		b.cond(fn, e.X, done, rhs)
		short = NewConst(constant.MakeBool(true), t)
	}

	// Is rhs unreachable?
	if rhs.Preds == nil {
		// Simplify false&&y to false, true||y to true.
		fn.currentBlock = done
		return short
	}

	// Is done unreachable?
	if done.Preds == nil {
		// Simplify true&&y (or false||y) to y.
		fn.currentBlock = rhs
		return b.expr(fn, e.Y)
	}

	// All edges from e.X to done carry the short-circuit value.
	var edges []Value
	for range done.Preds {
		edges = append(edges, short)
	}

	// The edge from e.Y to done carries the value of e.Y.
	fn.currentBlock = rhs
	edges = append(edges, b.expr(fn, e.Y))
	emitJump(fn, done)
	fn.currentBlock = done

	phi := &Phi{Edges: edges, Comment: e.Op.String()}
	phi.pos = e.OpPos
	phi.typ = t
	return done.emit(phi)
}

// exprN lowers a multi-result expression e to SSA form, emitting code
// to fn and returning a single Value whose type is a *types.Tuple.
// The caller must access the components via Extract.
//
// Multi-result expressions include CallExprs in a multi-value
// assignment or return statement, and "value,ok" uses of
// TypeAssertExpr, IndexExpr (when X is a map), and UnaryExpr (when Op
// is token.ARROW).
func (b *builder) exprN(fn *Function, e ast.Expr) Value {
	typ := fn.typeOf(e).(*types.Tuple)
	switch e := e.(type) {
	case *ast.ParenExpr:
		return b.exprN(fn, e.X)

	case *ast.CallExpr:
		// Currently, no built-in function nor type conversion
		// has multiple results, so we can avoid some of the
		// cases for single-valued CallExpr.
		var c Call
		b.setCall(fn, e, &c.Call)
		c.typ = typ
		return emitCall(fn, &c)

	case *ast.IndexExpr:
		mapt := typeparams.CoreType(fn.typeOf(e.X)).(*types.Map) // ,ok must be a map.
		lookup := &Lookup{
			X:       b.expr(fn, e.X),
			Index:   emitConv(fn, b.expr(fn, e.Index), mapt.Key()),
			CommaOk: true,
		}
		lookup.setType(typ)
		lookup.setPos(e.Lbrack)
		return fn.emit(lookup)

	case *ast.TypeAssertExpr:
		return emitTypeTest(fn, b.expr(fn, e.X), typ.At(0).Type(), e.Lparen)

	case *ast.UnaryExpr: // must be receive <-
		unop := &UnOp{
			Op:      token.ARROW,
			X:       b.expr(fn, e.X),
			CommaOk: true,
		}
		unop.setType(typ)
		unop.setPos(e.OpPos)
		return fn.emit(unop)
	}
	panic(fmt.Sprintf("exprN(%T) in %s", e, fn))
}

// builtin emits to fn SSA instructions to implement a call to the
// built-in function obj with the specified arguments
// and return type.  It returns the value defined by the result.
//
// The result is nil if no special handling was required; in this case
// the caller should treat this like an ordinary library function
// call.
func (b *builder) builtin(fn *Function, obj *types.Builtin, args []ast.Expr, typ types.Type, pos token.Pos) Value {
	typ = fn.typ(typ)
	switch obj.Name() {
	case "make":
		switch ct := typeparams.CoreType(typ).(type) {
		case *types.Slice:
			n := b.expr(fn, args[1])
			m := n
			if len(args) == 3 {
				m = b.expr(fn, args[2])
			}
			if m, ok := m.(*Const); ok {
				// treat make([]T, n, m) as new([m]T)[:n]
				cap := m.Int64()
				at := types.NewArray(ct.Elem(), cap)
				v := &Slice{
					X:    emitNew(fn, at, pos, "makeslice"),
					High: n,
				}
				v.setPos(pos)
				v.setType(typ)
				return fn.emit(v)
			}
			v := &MakeSlice{
				Len: n,
				Cap: m,
			}
			v.setPos(pos)
			v.setType(typ)
			return fn.emit(v)

		case *types.Map:
			var res Value
			if len(args) == 2 {
				res = b.expr(fn, args[1])
			}
			v := &MakeMap{Reserve: res}
			v.setPos(pos)
			v.setType(typ)
			return fn.emit(v)

		case *types.Chan:
			var sz Value = vZero
			if len(args) == 2 {
				sz = b.expr(fn, args[1])
			}
			v := &MakeChan{Size: sz}
			v.setPos(pos)
			v.setType(typ)
			return fn.emit(v)
		}

	case "new":
		alloc := emitNew(fn, typeparams.MustDeref(typ), pos, "new")
		if !fn.info.Types[args[0]].IsType() {
			// new(expr), requires go1.26
			v := b.expr(fn, args[0])
			emitStore(fn, alloc, v, pos)
		}
		return alloc

	case "len", "cap":
		// Special case: len or cap of an array or *array is
		// based on the type, not the value which may be nil.
		// We must still evaluate the value, though.  (If it
		// was side-effect free, the whole call would have
		// been constant-folded.)
		t := typeparams.Deref(fn.typeOf(args[0]))
		if at, ok := typeparams.CoreType(t).(*types.Array); ok {
			b.expr(fn, args[0]) // for effects only
			return intConst(at.Len())
		}
		// Otherwise treat as normal.

	case "panic":
		fn.emit(&Panic{
			X:   emitConv(fn, b.expr(fn, args[0]), tEface),
			pos: pos,
		})
		fn.currentBlock = fn.newBasicBlock("unreachable")
		return vTrue // any non-nil Value will do
	}
	return nil // treat all others as a regular function call
}

// addr lowers a single-result addressable expression e to SSA form,
// emitting code to fn and returning the location (an lvalue) defined
// by the expression.
//
// If escaping is true, addr marks the base variable of the
// addressable expression e as being a potentially escaping pointer
// value.  For example, in this code:
//
//	a := A{
//	  b: [1]B{B{c: 1}}
//	}
//	return &a.b[0].c
//
// the application of & causes a.b[0].c to have its address taken,
// which means that ultimately the local variable a must be
// heap-allocated.  This is a simple but very conservative escape
// analysis.
//
// Operations forming potentially escaping pointers include:
// - &x, including when implicit in method call or composite literals.
// - a[:] iff a is an array (not *array)
// - references to variables in lexically enclosing functions.
func (b *builder) addr(fn *Function, e ast.Expr, escaping bool) lvalue {
	switch e := e.(type) {
	case *ast.Ident:
		if isBlankIdent(e) {
			return blank{}
		}
		obj := fn.objectOf(e).(*types.Var)
		var v Value
		if g := fn.Prog.packageLevelMember(obj); g != nil {
			v = g.(*Global) // var (address)
		} else {
			v = fn.lookup(obj, escaping)
		}
		return &address{addr: v, pos: e.Pos(), expr: e}

	case *ast.CompositeLit:
		typ := typeparams.Deref(fn.typeOf(e))
		var v *Alloc
		if escaping {
			v = emitNew(fn, typ, e.Lbrace, "complit")
		} else {
			v = emitLocal(fn, typ, e.Lbrace, "complit")
		}
		var sb storebuf
		b.compLit(fn, v, e, true, &sb)
		sb.emit(fn)
		return &address{addr: v, pos: e.Lbrace, expr: e}

	case *ast.ParenExpr:
		return b.addr(fn, e.X, escaping)

	case *ast.SelectorExpr:
		sel := fn.selection(e)
		if sel == nil {
			// qualified identifier
			return b.addr(fn, e.Sel, escaping)
		}
		if sel.kind != types.FieldVal {
			panic(sel)
		}
		wantAddr := true
		v := b.receiver(fn, e.X, wantAddr, escaping, sel)
		index := sel.index[len(sel.index)-1]
		fld := fieldOf(typeparams.MustDeref(v.Type()), index) // v is an addr.

		// Due to the two phases of resolving AssignStmt, a panic from x.f = p()
		// when x is nil is required to come after the side-effects of
		// evaluating x and p().
		emit := func(fn *Function) Value {
			return emitFieldSelection(fn, v, index, true, e.Sel)
		}
		return &lazyAddress{addr: emit, t: fld.Type(), pos: e.Sel.Pos(), expr: e.Sel}

	case *ast.IndexExpr:
		xt := fn.typeOf(e.X)
		elem, mode := indexType(xt)
		var x Value
		var et types.Type
		switch mode {
		case ixArrVar: // array, array|slice, array|*array, or array|*array|slice.
			x = b.addr(fn, e.X, escaping).address(fn)
			et = types.NewPointer(elem)
		case ixVar: // *array, slice, *array|slice
			x = b.expr(fn, e.X)
			et = types.NewPointer(elem)
		case ixMap:
			mt := typeparams.CoreType(xt).(*types.Map)
			return &element{
				m:   b.expr(fn, e.X),
				k:   emitConv(fn, b.expr(fn, e.Index), mt.Key()),
				t:   mt.Elem(),
				pos: e.Lbrack,
			}
		default:
			panic("unexpected container type in IndexExpr: " + xt.String())
		}
		index := b.expr(fn, e.Index)
		if isUntyped(index.Type()) {
			index = emitConv(fn, index, tInt)
		}
		// Due to the two phases of resolving AssignStmt, a panic from x[i] = p()
		// when x is nil or i is out-of-bounds is required to come after the
		// side-effects of evaluating x, i and p().
		emit := func(fn *Function) Value {
			v := &IndexAddr{
				X:     x,
				Index: index,
			}
			v.setPos(e.Lbrack)
			v.setType(et)
			return fn.emit(v)
		}
		return &lazyAddress{addr: emit, t: typeparams.MustDeref(et), pos: e.Lbrack, expr: e}

	case *ast.StarExpr:
		return &address{addr: b.expr(fn, e.X), pos: e.Star, expr: e}
	}

	panic(fmt.Sprintf("unexpected address expression: %T", e))
}

type store struct {
	lhs lvalue
	rhs Value
}

type storebuf struct{ stores []store }

func (sb *storebuf) store(lhs lvalue, rhs Value) {
	sb.stores = append(sb.stores, store{lhs, rhs})
}

func (sb *storebuf) emit(fn *Function) {
	for _, s := range sb.stores {
		s.lhs.store(fn, s.rhs)
	}
}

// assign emits to fn code to initialize the lvalue loc with the value
// of expression e.  If isZero is true, assign assumes that loc holds
// the zero value for its type.
//
// This is equivalent to loc.store(fn, b.expr(fn, e)), but may generate
// better code in some cases, e.g., for composite literals in an
// addressable location.
//
// If sb is not nil, assign generates code to evaluate expression e, but
// not to update loc.  Instead, the necessary stores are appended to the
// storebuf sb so that they can be executed later.  This allows correct
// in-place update of existing variables when the RHS is a composite
// literal that may reference parts of the LHS.
func (b *builder) assign(fn *Function, loc lvalue, e ast.Expr, isZero bool, sb *storebuf) {
	// Can we initialize it in place?
	if e, ok := ast.Unparen(e).(*ast.CompositeLit); ok {
		// A CompositeLit never evaluates to a pointer,
		// so if the type of the location is a pointer,
		// an &-operation is implied.
		if !is[blank](loc) && isPointerCore(loc.typ()) { // avoid calling blank.typ()
			ptr := b.addr(fn, e, true).address(fn)
			// copy address
			if sb != nil {
				sb.store(loc, ptr)
			} else {
				loc.store(fn, ptr)
			}
			return
		}

		if _, ok := loc.(*address); ok {
			if isNonTypeParamInterface(loc.typ()) {
				// e.g. var x interface{} = T{...}
				// Can't in-place initialize an interface value.
				// Fall back to copying.
			} else {
				// x = T{...} or x := T{...}
				addr := loc.address(fn)
				if sb != nil {
					b.compLit(fn, addr, e, isZero, sb)
				} else {
					var sb storebuf
					b.compLit(fn, addr, e, isZero, &sb)
					sb.emit(fn)
				}

				// Subtle: emit debug ref for aggregate types only;
				// slice and map are handled by store ops in compLit.
				switch typeparams.CoreType(loc.typ()).(type) {
				case *types.Struct, *types.Array:
					emitDebugRef(fn, e, addr, true)
				}

				return
			}
		}
	}

	// simple case: just copy
	rhs := b.expr(fn, e)
	if sb != nil {
		sb.store(loc, rhs)
	} else {
		loc.store(fn, rhs)
	}
}

// expr lowers a single-result expression e to SSA form, emitting code
// to fn and returning the Value defined by the expression.
func (b *builder) expr(fn *Function, e ast.Expr) Value {
	e = ast.Unparen(e)

	tv := fn.info.Types[e]

	// Is expression a constant?
	if tv.Value != nil {
		return NewConst(tv.Value, fn.typ(tv.Type))
	}

	var v Value
	if tv.Addressable() {
		// Prefer pointer arithmetic ({Index,Field}Addr) followed
		// by Load over subelement extraction (e.g. Index, Field),
		// to avoid large copies.
		v = b.addr(fn, e, false).load(fn)
	} else {
		v = b.expr0(fn, e, tv)
	}
	if fn.debugInfo() {
		emitDebugRef(fn, e, v, false)
	}
	return v
}

func (b *builder) expr0(fn *Function, e ast.Expr, tv types.TypeAndValue) Value {
	switch e := e.(type) {
	case *ast.BasicLit:
		panic("non-constant BasicLit") // unreachable

	case *ast.FuncLit:
		/* function literal */
		anon := &Function{
			name:           fmt.Sprintf("%s$%d", fn.Name(), 1+len(fn.AnonFuncs)),
			Signature:      fn.typeOf(e.Type).(*types.Signature),
			pos:            e.Type.Func,
			parent:         fn,
			anonIdx:        int32(len(fn.AnonFuncs)),
			Pkg:            fn.Pkg,
			Prog:           fn.Prog,
			syntax:         e,
			info:           fn.info,
			goversion:      fn.goversion,
			build:          (*builder).buildFromSyntax,
			topLevelOrigin: nil,           // use anonIdx to lookup an anon instance's origin.
			typeparams:     fn.typeparams, // share the parent's type parameters.
			typeargs:       fn.typeargs,   // share the parent's type arguments.
			subst:          fn.subst,      // share the parent's type substitutions.
			uniq:           fn.uniq,       // start from parent's unique values
		}
		fn.AnonFuncs = append(fn.AnonFuncs, anon)
		// Build anon immediately, as it may cause fn's locals to escape.
		// (It is not marked 'built' until the end of the enclosing FuncDecl.)
		anon.build(b, anon)
		fn.uniq = anon.uniq // resume after anon's unique values
		if anon.FreeVars == nil {
			return anon
		}
		v := &MakeClosure{Fn: anon}
		v.setType(fn.typ(tv.Type))
		for _, fv := range anon.FreeVars {
			v.Bindings = append(v.Bindings, fv.outer)
			fv.outer = nil
		}
		return fn.emit(v)

	case *ast.TypeAssertExpr: // single-result form only
		return emitTypeAssert(fn, b.expr(fn, e.X), fn.typ(tv.Type), e.Lparen)

	case *ast.CallExpr:
		if fn.info.Types[e.Fun].IsType() {
			// Explicit type conversion, e.g. string(x) or big.Int(x)
			x := b.expr(fn, e.Args[0])
			y := emitConv(fn, x, fn.typ(tv.Type))
			if y != x {
				switch y := y.(type) {
				case *Convert:
					y.pos = e.Lparen
				case *ChangeType:
					y.pos = e.Lparen
				case *MakeInterface:
					y.pos = e.Lparen
				case *SliceToArrayPointer:
					y.pos = e.Lparen
				case *UnOp: // conversion from slice to array.
					y.pos = e.Lparen
				}
			}
			return y
		}
		// Call to "intrinsic" built-ins, e.g. new, make, panic.
		if id, ok := ast.Unparen(e.Fun).(*ast.Ident); ok {
			if obj, ok := fn.info.Uses[id].(*types.Builtin); ok {
				if v := b.builtin(fn, obj, e.Args, fn.typ(tv.Type), e.Lparen); v != nil {
					return v
				}
			}
		}
		// Regular function call.
		var v Call
		b.setCall(fn, e, &v.Call)
		v.setType(fn.typ(tv.Type))
		return emitCall(fn, &v)

	case *ast.UnaryExpr:
		switch e.Op {
		case token.AND: // &X --- potentially escaping.
			addr := b.addr(fn, e.X, true)
			if _, ok := ast.Unparen(e.X).(*ast.StarExpr); ok {
				// &*p must panic if p is nil (http://golang.org/s/go12nil).
				// For simplicity, we'll just (suboptimally) rely
				// on the side effects of a load.
				// TODO(adonovan): emit dedicated nilcheck.
				addr.load(fn)
			}
			return addr.address(fn)
		case token.ADD:
			return b.expr(fn, e.X)
		case token.NOT, token.ARROW, token.SUB, token.XOR: // ! <- - ^
			v := &UnOp{
				Op: e.Op,
				X:  b.expr(fn, e.X),
			}
			v.setPos(e.OpPos)
			v.setType(fn.typ(tv.Type))
			return fn.emit(v)
		default:
			panic(e.Op)
		}

	case *ast.BinaryExpr:
		switch e.Op {
		case token.LAND, token.LOR:
			return b.logicalBinop(fn, e)
		case token.SHL, token.SHR:
			fallthrough
		case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
			return emitArith(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), fn.typ(tv.Type), e.OpPos)

		case token.EQL, token.NEQ, token.GTR, token.LSS, token.LEQ, token.GEQ:
			cmp := emitCompare(fn, e.Op, b.expr(fn, e.X), b.expr(fn, e.Y), e.OpPos)
			// The type of x==y may be UntypedBool.
			return emitConv(fn, cmp, types.Default(fn.typ(tv.Type)))
		default:
			panic("illegal op in BinaryExpr: " + e.Op.String())
		}

	case *ast.SliceExpr:
		var low, high, max Value
		var x Value
		xtyp := fn.typeOf(e.X)
		switch typeparams.CoreType(xtyp).(type) {
		case *types.Array:
			// Potentially escaping.
			x = b.addr(fn, e.X, true).address(fn)
		case *types.Basic, *types.Slice, *types.Pointer: // *array
			x = b.expr(fn, e.X)
		default:
			// core type exception?
			if isBytestring(xtyp) {
				x = b.expr(fn, e.X) // bytestring is handled as string and []byte.
			} else {
				panic("unexpected sequence type in SliceExpr")
			}
		}
		if e.Low != nil {
			low = b.expr(fn, e.Low)
		}
		if e.High != nil {
			high = b.expr(fn, e.High)
		}
		if e.Slice3 {
			max = b.expr(fn, e.Max)
		}
		v := &Slice{
			X:    x,
			Low:  low,
			High: high,
			Max:  max,
		}
		v.setPos(e.Lbrack)
		v.setType(fn.typ(tv.Type))
		return fn.emit(v)

	case *ast.Ident:
		obj := fn.info.Uses[e]
		// Universal built-in or nil?
		switch obj := obj.(type) {
		case *types.Builtin:
			return &Builtin{name: obj.Name(), sig: fn.instanceType(e).(*types.Signature)}
		case *types.Nil:
			return zeroConst(fn.instanceType(e))
		}

		// Package-level func or var?
		// (obj must belong to same package or a direct import.)
		if v := fn.Prog.packageLevelMember(obj); v != nil {
			if g, ok := v.(*Global); ok {
				return emitLoad(fn, g) // var (address)
			}
			callee := v.(*Function) // (func)
			if callee.typeparams.Len() > 0 {
				targs := fn.subst.types(instanceArgs(fn.info, e))
				callee = callee.instance(targs, b)
			}
			return callee
		}
		// Local var.
		return emitLoad(fn, fn.lookup(obj.(*types.Var), false)) // var (address)

	case *ast.SelectorExpr:
		sel := fn.selection(e)
		if sel == nil {
			// builtin unsafe.{Add,Slice}
			if obj, ok := fn.info.Uses[e.Sel].(*types.Builtin); ok {
				return &Builtin{name: obj.Name(), sig: fn.typ(tv.Type).(*types.Signature)}
			}
			// qualified identifier
			return b.expr(fn, e.Sel)
		}
		switch sel.kind {
		case types.MethodExpr:
			// (*T).f or T.f, the method f from the method-set of type T.
			// The result is a "thunk".
			thunk := createThunk(fn.Prog, sel)
			b.enqueue(thunk)
			return emitConv(fn, thunk, fn.typ(tv.Type))

		case types.MethodVal:
			// e.f where e is an expression and f is a method.
			// The result is a "bound".
			obj := sel.obj.(*types.Func)
			rt := fn.typ(recvType(obj))
			wantAddr := isPointer(rt)
			escaping := true
			v := b.receiver(fn, e.X, wantAddr, escaping, sel)

			if types.IsInterface(rt) {
				// If v may be an interface type I (after instantiating),
				// we must emit a check that v is non-nil.
				if recv, ok := types.Unalias(sel.recv).(*types.TypeParam); ok {
					// Emit a nil check if any possible instantiation of the
					// type parameter is an interface type.
					if !typeSetIsEmpty(recv) {
						// recv has a concrete term its typeset.
						// So it cannot be instantiated as an interface.
						//
						// Example:
						// func _[T interface{~int; Foo()}] () {
						//    var v T
						//    _ = v.Foo // <-- MethodVal
						// }
					} else {
						// rt may be instantiated as an interface.
						// Emit nil check: typeassert (any(v)).(any).
						emitTypeAssert(fn, emitConv(fn, v, tEface), tEface, token.NoPos)
					}
				} else {
					// non-type param interface
					// Emit nil check: typeassert v.(I).
					emitTypeAssert(fn, v, rt, e.Sel.Pos())
				}
			}
			if targs := receiverTypeArgs(obj); len(targs) > 0 {
				// obj is generic.
				obj = fn.Prog.canon.instantiateMethod(obj, fn.subst.types(targs), fn.Prog.ctxt)
			}
			bound := createBound(fn.Prog, obj)
			b.enqueue(bound)

			c := &MakeClosure{
				Fn:       bound,
				Bindings: []Value{v},
			}
			c.setPos(e.Sel.Pos())
			c.setType(fn.typ(tv.Type))
			return fn.emit(c)

		case types.FieldVal:
			indices := sel.index
			last := len(indices) - 1
			v := b.expr(fn, e.X)
			v = emitImplicitSelections(fn, v, indices[:last], e.Pos())
			v = emitFieldSelection(fn, v, indices[last], false, e.Sel)
			return v
		}

		panic("unexpected expression-relative selector")

	case *ast.IndexListExpr:
		// f[X, Y] must be a generic function
		if !instance(fn.info, e.X) {
			panic("unexpected expression-could not match index list to instantiation")
		}
		return b.expr(fn, e.X) // Handle instantiation within the *Ident or *SelectorExpr cases.

	case *ast.IndexExpr:
		if instance(fn.info, e.X) {
			return b.expr(fn, e.X) // Handle instantiation within the *Ident or *SelectorExpr cases.
		}
		// not a generic instantiation.
		xt := fn.typeOf(e.X)
		switch et, mode := indexType(xt); mode {
		case ixVar:
			// Addressable slice/array; use IndexAddr and Load.
			return b.addr(fn, e, false).load(fn)

		case ixArrVar, ixValue:
			// An array in a register, a string or a combined type that contains
			// either an [_]array (ixArrVar) or string (ixValue).

			// Note: for ixArrVar and CoreType(xt)==nil can be IndexAddr and Load.
			index := b.expr(fn, e.Index)
			if isUntyped(index.Type()) {
				index = emitConv(fn, index, tInt)
			}
			v := &Index{
				X:     b.expr(fn, e.X),
				Index: index,
			}
			v.setPos(e.Lbrack)
			v.setType(et)
			return fn.emit(v)

		case ixMap:
			ct := typeparams.CoreType(xt).(*types.Map)
			v := &Lookup{
				X:     b.expr(fn, e.X),
				Index: emitConv(fn, b.expr(fn, e.Index), ct.Key()),
			}
			v.setPos(e.Lbrack)
			v.setType(ct.Elem())
			return fn.emit(v)
		default:
			panic("unexpected container type in IndexExpr: " + xt.String())
		}

	case *ast.CompositeLit, *ast.StarExpr:
		// Addressable types (lvalues)
		return b.addr(fn, e, false).load(fn)
	}

	panic(fmt.Sprintf("unexpected expr: %T", e))
}

// stmtList emits to fn code for all statements in list.
func (b *builder) stmtList(fn *Function, list []ast.Stmt) {
	for _, s := range list {
		b.stmt(fn, s)
	}
}

// receiver emits to fn code for expression e in the "receiver"
// position of selection e.f (where f may be a field or a method) and
// returns the effective receiver after applying the implicit field
// selections of sel.
//
// wantAddr requests that the result is an address.  If
// !sel.indirect, this may require that e be built in addr() mode; it
// must thus be addressable.
//
// escaping is defined as per builder.addr().
func (b *builder) receiver(fn *Function, e ast.Expr, wantAddr, escaping bool, sel *selection) Value {
	var v Value
	if wantAddr && !sel.indirect && !isPointerCore(fn.typeOf(e)) {
		v = b.addr(fn, e, escaping).address(fn)
	} else {
		v = b.expr(fn, e)
	}

	last := len(sel.index) - 1
	// The position of implicit selection is the position of the inducing receiver expression.
	v = emitImplicitSelections(fn, v, sel.index[:last], e.Pos())
	if types.IsInterface(v.Type()) {
		// When v is an interface, sel.Kind()==MethodValue and v.f is invoked.
		// So v is not loaded, even if v has a pointer core type.
	} else if !wantAddr && isPointerCore(v.Type()) {
		v = emitLoad(fn, v)
	}
	return v
}

// setCallFunc populates the function parts of a CallCommon structure
// (Func, Method, Recv, Args[0]) based on the kind of invocation
// occurring in e.
func (b *builder) setCallFunc(fn *Function, e *ast.CallExpr, c *CallCommon) {
	c.pos = e.Lparen

	// Is this a method call?
	if selector, ok := ast.Unparen(e.Fun).(*ast.SelectorExpr); ok {
		sel := fn.selection(selector)
		if sel != nil && sel.kind == types.MethodVal {
			obj := sel.obj.(*types.Func)
			recv := recvType(obj)

			wantAddr := isPointer(recv)
			escaping := true
			v := b.receiver(fn, selector.X, wantAddr, escaping, sel)
			if types.IsInterface(recv) {
				// Invoke-mode call.
				c.Value = v // possibly type param
				c.Method = obj
			} else {
				// "Call"-mode call.
				c.Value = fn.Prog.objectMethod(obj, b)
				c.Args = append(c.Args, v)
			}
			return
		}

		// sel.kind==MethodExpr indicates T.f() or (*T).f():
		// a statically dispatched call to the method f in the
		// method-set of T or *T.  T may be an interface.
		//
		// e.Fun would evaluate to a concrete method, interface
		// wrapper function, or promotion wrapper.
		//
		// For now, we evaluate it in the usual way.
		//
		// TODO(adonovan): opt: inline expr() here, to make the
		// call static and to avoid generation of wrappers.
		// It's somewhat tricky as it may consume the first
		// actual parameter if the call is "invoke" mode.
		//
		// Examples:
		//  type T struct{}; func (T) f() {}   // "call" mode
		//  type T interface { f() }           // "invoke" mode
		//
		//  type S struct{ T }
		//
		//  var s S
		//  S.f(s)
		//  (*S).f(&s)
		//
		// Suggested approach:
		// - consume the first actual parameter expression
		//   and build it with b.expr().
		// - apply implicit field selections.
		// - use MethodVal logic to populate fields of c.
	}

	// Evaluate the function operand in the usual way.
	c.Value = b.expr(fn, e.Fun)
}

// emitCallArgs emits to f code for the actual parameters of call e to
// a (possibly built-in) function of effective type sig.
// The argument values are appended to args, which is then returned.
func (b *builder) emitCallArgs(fn *Function, sig *types.Signature, e *ast.CallExpr, args []Value) []Value {
	// f(x, y, z...): pass slice z straight through.
	if e.Ellipsis != 0 {
		for i, arg := range e.Args {
			v := emitConv(fn, b.expr(fn, arg), sig.Params().At(i).Type())
			args = append(args, v)
		}
		return args
	}

	offset := len(args) // 1 if call has receiver, 0 otherwise

	// Evaluate actual parameter expressions.
	//
	// If this is a chained call of the form f(g()) where g has
	// multiple return values (MRV), they are flattened out into
	// args; a suffix of them may end up in a varargs slice.
	for _, arg := range e.Args {
		v := b.expr(fn, arg)
		if ttuple, ok := v.Type().(*types.Tuple); ok { // MRV chain
			for i, n := 0, ttuple.Len(); i < n; i++ {
				args = append(args, emitExtract(fn, v, i))
			}
		} else {
			args = append(args, v)
		}
	}

	// Actual->formal assignability conversions for normal parameters.
	np := sig.Params().Len() // number of normal parameters
	if sig.Variadic() {
		np--
	}
	for i := 0; i < np; i++ {
		args[offset+i] = emitConv(fn, args[offset+i], sig.Params().At(i).Type())
	}

	// Actual->formal assignability conversions for variadic parameter,
	// and construction of slice.
	if sig.Variadic() {
		varargs := args[offset+np:]
		st := sig.Params().At(np).Type().(*types.Slice)
		vt := st.Elem()
		if len(varargs) == 0 {
			args = append(args, zeroConst(st))
		} else {
			// Replace a suffix of args with a slice containing it.
			at := types.NewArray(vt, int64(len(varargs)))
			a := emitNew(fn, at, token.NoPos, "varargs")
			a.setPos(e.Rparen)
			for i, arg := range varargs {
				iaddr := &IndexAddr{
					X:     a,
					Index: intConst(int64(i)),
				}
				iaddr.setType(types.NewPointer(vt))
				fn.emit(iaddr)
				emitStore(fn, iaddr, arg, arg.Pos())
			}
			s := &Slice{X: a}
			s.setType(st)
			args[offset+np] = fn.emit(s)
			args = args[:offset+np+1]
		}
	}
	return args
}

// setCall emits to fn code to evaluate all the parameters of a function
// call e, and populates *c with those values.
func (b *builder) setCall(fn *Function, e *ast.CallExpr, c *CallCommon) {
	// First deal with the f(...) part and optional receiver.
	b.setCallFunc(fn, e, c)

	// Then append the other actual parameters.
	sig, _ := typeparams.CoreType(fn.typeOf(e.Fun)).(*types.Signature)
	if sig == nil {
		panic(fmt.Sprintf("no signature for call of %s", e.Fun))
	}
	c.Args = b.emitCallArgs(fn, sig, e, c.Args)
}

// assignOp emits to fn code to perform loc <op>= val.
func (b *builder) assignOp(fn *Function, loc lvalue, val Value, op token.Token, pos token.Pos) {
	loc.store(fn, emitArith(fn, op, loc.load(fn), val, loc.typ(), pos))
}

// localValueSpec emits to fn code to define all of the vars in the
// function-local ValueSpec, spec.
func (b *builder) localValueSpec(fn *Function, spec *ast.ValueSpec) {
	switch {
	case len(spec.Values) == len(spec.Names):
		// e.g. var x, y = 0, 1
		// 1:1 assignment
		for i, id := range spec.Names {
			if !isBlankIdent(id) {
				emitLocalVar(fn, identVar(fn, id))
			}
			lval := b.addr(fn, id, false) // non-escaping
			b.assign(fn, lval, spec.Values[i], true, nil)
		}

	case len(spec.Values) == 0:
		// e.g. var x, y int
		// Locals are implicitly zero-initialized.
		for _, id := range spec.Names {
			if !isBlankIdent(id) {
				lhs := emitLocalVar(fn, identVar(fn, id))
				if fn.debugInfo() {
					emitDebugRef(fn, id, lhs, true)
				}
			}
		}

	default:
		// e.g. var x, y = pos()
		tuple := b.exprN(fn, spec.Values[0])
		for i, id := range spec.Names {
			if !isBlankIdent(id) {
				emitLocalVar(fn, identVar(fn, id))
				lhs := b.addr(fn, id, false) // non-escaping
				lhs.store(fn, emitExtract(fn, tuple, i))
			}
		}
	}
}

// assignStmt emits code to fn for a parallel assignment of rhss to lhss.
// isDef is true if this is a short variable declaration (:=).
//
// Note the similarity with localValueSpec.
func (b *builder) assignStmt(fn *Function, lhss, rhss []ast.Expr, isDef bool) {
	// Side effects of all LHSs and RHSs must occur in left-to-right order.
	lvals := make([]lvalue, len(lhss))
	isZero := make([]bool, len(lhss))
	for i, lhs := range lhss {
		var lval lvalue = blank{}
		if !isBlankIdent(lhs) {
			if isDef {
				if obj, ok := fn.info.Defs[lhs.(*ast.Ident)].(*types.Var); ok {
					emitLocalVar(fn, obj)
					isZero[i] = true
				}
			}
			lval = b.addr(fn, lhs, false) // non-escaping
		}
		lvals[i] = lval
	}
	if len(lhss) == len(rhss) {
		// Simple assignment:   x     = f()        (!isDef)
		// Parallel assignment: x, y  = f(), g()   (!isDef)
		// or short var decl:   x, y := f(), g()   (isDef)
		//
		// In all cases, the RHSs may refer to the LHSs,
		// so we need a storebuf.
		var sb storebuf
		for i := range rhss {
			b.assign(fn, lvals[i], rhss[i], isZero[i], &sb)
		}
		sb.emit(fn)
	} else {
		// e.g. x, y = pos()
		tuple := b.exprN(fn, rhss[0])
		emitDebugRef(fn, rhss[0], tuple, false)
		for i, lval := range lvals {
			lval.store(fn, emitExtract(fn, tuple, i))
		}
	}
}

// arrayLen returns the length of the array whose composite literal elements are elts.
func (b *builder) arrayLen(fn *Function, elts []ast.Expr) int64 {
	var max int64 = -1
	var i int64 = -1
	for _, e := range elts {
		if kv, ok := e.(*ast.KeyValueExpr); ok {
			i = b.expr(fn, kv.Key).(*Const).Int64()
		} else {
			i++
		}
		if i > max {
			max = i
		}
	}
	return max + 1
}

// compLit emits to fn code to initialize a composite literal e at
// address addr with type typ.
//
// Nested composite literals are recursively initialized in place
// where possible. If isZero is true, compLit assumes that addr
// holds the zero value for typ.
//
// Because the elements of a composite literal may refer to the
// variables being updated, as in the second line below,
//
//	x := T{a: 1}
//	x = T{a: x.a}
//
// all the reads must occur before all the writes.  Thus all stores to
// loc are emitted to the storebuf sb for later execution.
//
// A CompositeLit may have pointer type only in the recursive (nested)
// case when the type name is implicit.  e.g. in []*T{{}}, the inner
// literal has type *T behaves like &T{}.
// In that case, addr must hold a T, not a *T.
func (b *builder) compLit(fn *Function, addr Value, e *ast.CompositeLit, isZero bool, sb *storebuf) {
	typ := typeparams.Deref(fn.typeOf(e)) // retain the named/alias/param type, if any
	switch t := typeparams.CoreType(typ).(type) {
	case *types.Struct:
		if !isZero && len(e.Elts) != t.NumFields() {
			// memclear
			zt := typeparams.MustDeref(addr.Type())
			sb.store(&address{addr, e.Lbrace, nil}, zeroConst(zt))
			isZero = true
		}
		for i, e := range e.Elts {
			fieldIndex := i
			pos := e.Pos()
			if kv, ok := e.(*ast.KeyValueExpr); ok {
				fname := kv.Key.(*ast.Ident).Name
				for i, n := 0, t.NumFields(); i < n; i++ {
					sf := t.Field(i)
					if sf.Name() == fname {
						fieldIndex = i
						pos = kv.Colon
						e = kv.Value
						break
					}
				}
			}
			sf := t.Field(fieldIndex)
			faddr := &FieldAddr{
				X:     addr,
				Field: fieldIndex,
			}
			faddr.setPos(pos)
			faddr.setType(types.NewPointer(sf.Type()))
			fn.emit(faddr)
			b.assign(fn, &address{addr: faddr, pos: pos, expr: e}, e, isZero, sb)
		}

	case *types.Array, *types.Slice:
		var at *types.Array
		var array Value
		switch t := t.(type) {
		case *types.Slice:
			at = types.NewArray(t.Elem(), b.arrayLen(fn, e.Elts))
			array = emitNew(fn, at, e.Lbrace, "slicelit")
		case *types.Array:
			at = t
			array = addr

			if !isZero && int64(len(e.Elts)) != at.Len() {
				// memclear
				zt := typeparams.MustDeref(array.Type())
				sb.store(&address{array, e.Lbrace, nil}, zeroConst(zt))
			}
		}

		var idx *Const
		for _, e := range e.Elts {
			pos := e.Pos()
			if kv, ok := e.(*ast.KeyValueExpr); ok {
				idx = b.expr(fn, kv.Key).(*Const)
				pos = kv.Colon
				e = kv.Value
			} else {
				var idxval int64
				if idx != nil {
					idxval = idx.Int64() + 1
				}
				idx = intConst(idxval)
			}
			iaddr := &IndexAddr{
				X:     array,
				Index: idx,
			}
			iaddr.setType(types.NewPointer(at.Elem()))
			fn.emit(iaddr)
			if t != at { // slice
				// backing array is unaliased => storebuf not needed.
				b.assign(fn, &address{addr: iaddr, pos: pos, expr: e}, e, true, nil)
			} else {
				b.assign(fn, &address{addr: iaddr, pos: pos, expr: e}, e, true, sb)
			}
		}

		if t != at { // slice
			s := &Slice{X: array}
			s.setPos(e.Lbrace)
			s.setType(typ)
			sb.store(&address{addr: addr, pos: e.Lbrace, expr: e}, fn.emit(s))
		}

	case *types.Map:
		m := &MakeMap{Reserve: intConst(int64(len(e.Elts)))}
		m.setPos(e.Lbrace)
		m.setType(typ)
		fn.emit(m)
		for _, e := range e.Elts {
			e := e.(*ast.KeyValueExpr)

			// If a key expression in a map literal is itself a
			// composite literal, the type may be omitted.
			// For example:
			//	map[*struct{}]bool{{}: true}
			// An &-operation may be implied:
			//	map[*struct{}]bool{&struct{}{}: true}
			wantAddr := false
			if _, ok := ast.Unparen(e.Key).(*ast.CompositeLit); ok {
				wantAddr = isPointerCore(t.Key())
			}

			var key Value
			if wantAddr {
				// A CompositeLit never evaluates to a pointer,
				// so if the type of the location is a pointer,
				// an &-operation is implied.
				key = b.addr(fn, e.Key, true).address(fn)
			} else {
				key = b.expr(fn, e.Key)
			}

			loc := element{
				m:   m,
				k:   emitConv(fn, key, t.Key()),
				t:   t.Elem(),
				pos: e.Colon,
			}

			// We call assign() only because it takes care
			// of any &-operation required in the recursive
			// case, e.g.,
			// map[int]*struct{}{0: {}} implies &struct{}{}.
			// In-place update is of course impossible,
			// and no storebuf is needed.
			b.assign(fn, &loc, e.Value, true, nil)
		}
		sb.store(&address{addr: addr, pos: e.Lbrace, expr: e}, m)

	default:
		panic("unexpected CompositeLit type: " + typ.String())
	}
}

// switchStmt emits to fn code for the switch statement s, optionally
// labelled by label.
func (b *builder) switchStmt(fn *Function, s *ast.SwitchStmt, label *lblock) {
	// We treat SwitchStmt like a sequential if-else chain.
	// Multiway dispatch can be recovered later by ssautil.Switches()
	// to those cases that are free of side effects.
	if s.Init != nil {
		b.stmt(fn, s.Init)
	}
	var tag Value = vTrue
	if s.Tag != nil {
		tag = b.expr(fn, s.Tag)
	}
	done := fn.newBasicBlock("switch.done")
	if label != nil {
		label._break = done
	}
	// We pull the default case (if present) down to the end.
	// But each fallthrough label must point to the next
	// body block in source order, so we preallocate a
	// body block (fallthru) for the next case.
	// Unfortunately this makes for a confusing block order.
	var dfltBody *[]ast.Stmt
	var dfltFallthrough *BasicBlock
	var fallthru, dfltBlock *BasicBlock
	ncases := len(s.Body.List)
	for i, clause := range s.Body.List {
		body := fallthru
		if body == nil {
			body = fn.newBasicBlock("switch.body") // first case only
		}

		// Preallocate body block for the next case.
		fallthru = done
		if i+1 < ncases {
			fallthru = fn.newBasicBlock("switch.body")
		}

		cc := clause.(*ast.CaseClause)
		if cc.List == nil {
			// Default case.
			dfltBody = &cc.Body
			dfltFallthrough = fallthru
			dfltBlock = body
			continue
		}

		var nextCond *BasicBlock
		for _, cond := range cc.List {
			nextCond = fn.newBasicBlock("switch.next")
			// For boolean switches, emit short-circuit control flow,
			// just like an if/else-chain.
			if tag == vTrue && !isNonTypeParamInterface(fn.info.Types[cond].Type) {
				b.cond(fn, cond, body, nextCond)
			} else {
				c := emitCompare(fn, token.EQL, tag, b.expr(fn, cond), cond.Pos())
				emitIf(fn, c, body, nextCond)
			}
			fn.currentBlock = nextCond
		}
		fn.currentBlock = body
		fn.targets = &targets{
			tail:         fn.targets,
			_break:       done,
			_fallthrough: fallthru,
		}
		b.stmtList(fn, cc.Body)
		fn.targets = fn.targets.tail
		emitJump(fn, done)
		fn.currentBlock = nextCond
	}
	if dfltBlock != nil {
		emitJump(fn, dfltBlock)
		fn.currentBlock = dfltBlock
		fn.targets = &targets{
			tail:         fn.targets,
			_break:       done,
			_fallthrough: dfltFallthrough,
		}
		b.stmtList(fn, *dfltBody)
		fn.targets = fn.targets.tail
	}
	emitJump(fn, done)
	fn.currentBlock = done
}

// typeSwitchStmt emits to fn code for the type switch statement s, optionally
// labelled by label.
func (b *builder) typeSwitchStmt(fn *Function, s *ast.TypeSwitchStmt, label *lblock) {
	// We treat TypeSwitchStmt like a sequential if-else chain.
	// Multiway dispatch can be recovered later by ssautil.Switches().

	// Typeswitch lowering:
	//
	// var x X
	// switch y := x.(type) {
	// case T1, T2: S1                  // >1 	(y := x)
	// case nil:    SN                  // nil 	(y := x)
	// default:     SD                  // 0 types 	(y := x)
	// case T3:     S3                  // 1 type 	(y := x.(T3))
	// }
	//
	//      ...s.Init...
	// 	x := eval x
	// .caseT1:
	// 	t1, ok1 := typeswitch,ok x <T1>
	// 	if ok1 then goto S1 else goto .caseT2
	// .caseT2:
	// 	t2, ok2 := typeswitch,ok x <T2>
	// 	if ok2 then goto S1 else goto .caseNil
	// .S1:
	//      y := x
	// 	...S1...
	// 	goto done
	// .caseNil:
	// 	if t2, ok2 := typeswitch,ok x <T2>
	// 	if x == nil then goto SN else goto .caseT3
	// .SN:
	//      y := x
	// 	...SN...
	// 	goto done
	// .caseT3:
	// 	t3, ok3 := typeswitch,ok x <T3>
	// 	if ok3 then goto S3 else goto default
	// .S3:
	//      y := t3
	// 	...S3...
	// 	goto done
	// .default:
	//      y := x
	// 	...SD...
	// 	goto done
	// .done:
	if s.Init != nil {
		b.stmt(fn, s.Init)
	}

	var x Value
	switch ass := s.Assign.(type) {
	case *ast.ExprStmt: // x.(type)
		x = b.expr(fn, ast.Unparen(ass.X).(*ast.TypeAssertExpr).X)
	case *ast.AssignStmt: // y := x.(type)
		x = b.expr(fn, ast.Unparen(ass.Rhs[0]).(*ast.TypeAssertExpr).X)
	}

	done := fn.newBasicBlock("typeswitch.done")
	if label != nil {
		label._break = done
	}
	var default_ *ast.CaseClause
	for _, clause := range s.Body.List {
		cc := clause.(*ast.CaseClause)
		if cc.List == nil {
			default_ = cc
			continue
		}
		body := fn.newBasicBlock("typeswitch.body")
		var next *BasicBlock
		var casetype types.Type
		var ti Value // ti, ok := typeassert,ok x <Ti>
		for _, cond := range cc.List {
			next = fn.newBasicBlock("typeswitch.next")
			casetype = fn.typeOf(cond)
			var condv Value
			if casetype == tUntypedNil {
				condv = emitCompare(fn, token.EQL, x, zeroConst(x.Type()), cond.Pos())
				ti = x
			} else {
				yok := emitTypeTest(fn, x, casetype, cc.Case)
				ti = emitExtract(fn, yok, 0)
				condv = emitExtract(fn, yok, 1)
			}
			emitIf(fn, condv, body, next)
			fn.currentBlock = next
		}
		if len(cc.List) != 1 {
			ti = x
		}
		fn.currentBlock = body
		b.typeCaseBody(fn, cc, ti, done)
		fn.currentBlock = next
	}
	if default_ != nil {
		b.typeCaseBody(fn, default_, x, done)
	} else {
		emitJump(fn, done)
	}
	fn.currentBlock = done
}

func (b *builder) typeCaseBody(fn *Function, cc *ast.CaseClause, x Value, done *BasicBlock) {
	if obj, ok := fn.info.Implicits[cc].(*types.Var); ok {
		// In a switch y := x.(type), each case clause
		// implicitly declares a distinct object y.
		// In a single-type case, y has that type.
		// In multi-type cases, 'case nil' and default,
		// y has the same type as the interface operand.
		emitStore(fn, emitLocalVar(fn, obj), x, obj.Pos())
	}
	fn.targets = &targets{
		tail:   fn.targets,
		_break: done,
	}
	b.stmtList(fn, cc.Body)
	fn.targets = fn.targets.tail
	emitJump(fn, done)
}

// selectStmt emits to fn code for the select statement s, optionally
// labelled by label.
func (b *builder) selectStmt(fn *Function, s *ast.SelectStmt, label *lblock) {
	// A blocking select of a single case degenerates to a
	// simple send or receive.
	// TODO(adonovan): opt: is this optimization worth its weight?
	if len(s.Body.List) == 1 {
		clause := s.Body.List[0].(*ast.CommClause)
		if clause.Comm != nil {
			b.stmt(fn, clause.Comm)
			done := fn.newBasicBlock("select.done")
			if label != nil {
				label._break = done
			}
			fn.targets = &targets{
				tail:   fn.targets,
				_break: done,
			}
			b.stmtList(fn, clause.Body)
			fn.targets = fn.targets.tail
			emitJump(fn, done)
			fn.currentBlock = done
			return
		}
	}

	// First evaluate all channels in all cases, and find
	// the directions of each state.
	var states []*SelectState
	blocking := true
	debugInfo := fn.debugInfo()
	for _, clause := range s.Body.List {
		var st *SelectState
		switch comm := clause.(*ast.CommClause).Comm.(type) {
		case nil: // default case
			blocking = false
			continue

		case *ast.SendStmt: // ch<- i
			ch := b.expr(fn, comm.Chan)
			chtyp := typeparams.CoreType(fn.typ(ch.Type())).(*types.Chan)
			st = &SelectState{
				Dir:  types.SendOnly,
				Chan: ch,
				Send: emitConv(fn, b.expr(fn, comm.Value), chtyp.Elem()),
				Pos:  comm.Arrow,
			}
			if debugInfo {
				st.DebugNode = comm
			}

		case *ast.AssignStmt: // x := <-ch
			recv := ast.Unparen(comm.Rhs[0]).(*ast.UnaryExpr)
			st = &SelectState{
				Dir:  types.RecvOnly,
				Chan: b.expr(fn, recv.X),
				Pos:  recv.OpPos,
			}
			if debugInfo {
				st.DebugNode = recv
			}

		case *ast.ExprStmt: // <-ch
			recv := ast.Unparen(comm.X).(*ast.UnaryExpr)
			st = &SelectState{
				Dir:  types.RecvOnly,
				Chan: b.expr(fn, recv.X),
				Pos:  recv.OpPos,
			}
			if debugInfo {
				st.DebugNode = recv
			}
		}
		states = append(states, st)
	}

	// We dispatch on the (fair) result of Select using a
	// sequential if-else chain, in effect:
	//
	// idx, recvOk, r0...r_n-1 := select(...)
	// if idx == 0 {  // receive on channel 0  (first receive => r0)
	//     x, ok := r0, recvOk
	//     ...state0...
	// } else if v == 1 {   // send on channel 1
	//     ...state1...
	// } else {
	//     ...default...
	// }
	sel := &Select{
		States:   states,
		Blocking: blocking,
	}
	sel.setPos(s.Select)
	var vars []*types.Var
	vars = append(vars, varIndex, varOk)
	for _, st := range states {
		if st.Dir == types.RecvOnly {
			chtyp := typeparams.CoreType(fn.typ(st.Chan.Type())).(*types.Chan)
			vars = append(vars, anonVar(chtyp.Elem()))
		}
	}
	sel.setType(types.NewTuple(vars...))

	fn.emit(sel)
	idx := emitExtract(fn, sel, 0)

	done := fn.newBasicBlock("select.done")
	if label != nil {
		label._break = done
	}

	var defaultBody *[]ast.Stmt
	state := 0
	r := 2 // index in 'sel' tuple of value; increments if st.Dir==RECV
	for _, cc := range s.Body.List {
		clause := cc.(*ast.CommClause)
		if clause.Comm == nil {
			defaultBody = &clause.Body
			continue
		}
		body := fn.newBasicBlock("select.body")
		next := fn.newBasicBlock("select.next")
		emitIf(fn, emitCompare(fn, token.EQL, idx, intConst(int64(state)), token.NoPos), body, next)
		fn.currentBlock = body
		fn.targets = &targets{
			tail:   fn.targets,
			_break: done,
		}
		switch comm := clause.Comm.(type) {
		case *ast.ExprStmt: // <-ch
			if debugInfo {
				v := emitExtract(fn, sel, r)
				emitDebugRef(fn, states[state].DebugNode.(ast.Expr), v, false)
			}
			r++

		case *ast.AssignStmt: // x := <-states[state].Chan
			if comm.Tok == token.DEFINE {
				emitLocalVar(fn, identVar(fn, comm.Lhs[0].(*ast.Ident)))
			}
			x := b.addr(fn, comm.Lhs[0], false) // non-escaping
			v := emitExtract(fn, sel, r)
			if debugInfo {
				emitDebugRef(fn, states[state].DebugNode.(ast.Expr), v, false)
			}
			x.store(fn, v)

			if len(comm.Lhs) == 2 { // x, ok := ...
				if comm.Tok == token.DEFINE {
					emitLocalVar(fn, identVar(fn, comm.Lhs[1].(*ast.Ident)))
				}
				ok := b.addr(fn, comm.Lhs[1], false) // non-escaping
				ok.store(fn, emitExtract(fn, sel, 1))
			}
			r++
		}
		b.stmtList(fn, clause.Body)
		fn.targets = fn.targets.tail
		emitJump(fn, done)
		fn.currentBlock = next
		state++
	}
	if defaultBody != nil {
		fn.targets = &targets{
			tail:   fn.targets,
			_break: done,
		}
		b.stmtList(fn, *defaultBody)
		fn.targets = fn.targets.tail
	} else {
		// A blocking select must match some case.
		// (This should really be a runtime.errorString, not a string.)
		fn.emit(&Panic{
			X: emitConv(fn, stringConst("blocking select matched no case"), tEface),
		})
		fn.currentBlock = fn.newBasicBlock("unreachable")
	}
	emitJump(fn, done)
	fn.currentBlock = done
}

// forStmt emits to fn code for the for statement s, optionally
// labelled by label.
func (b *builder) forStmt(fn *Function, s *ast.ForStmt, label *lblock) {
	// Use forStmtGo122 instead if it applies.
	if s.Init != nil {
		if assign, ok := s.Init.(*ast.AssignStmt); ok && assign.Tok == token.DEFINE {
			if versions.AtLeast(fn.goversion, versions.Go1_22) {
				b.forStmtGo122(fn, s, label)
				return
			}
		}
	}

	//     ...init...
	//     jump loop
	// loop:
	//     if cond goto body else done
	// body:
	//     ...body...
	//     jump post
	// post:                                 (target of continue)
	//     ...post...
	//     jump loop
	// done:                                 (target of break)
	if s.Init != nil {
		b.stmt(fn, s.Init)
	}

	body := fn.newBasicBlock("for.body")
	done := fn.newBasicBlock("for.done") // target of 'break'
	loop := body                         // target of back-edge
	if s.Cond != nil {
		loop = fn.newBasicBlock("for.loop")
	}
	cont := loop // target of 'continue'
	if s.Post != nil {
		cont = fn.newBasicBlock("for.post")
	}
	if label != nil {
		label._break = done
		label._continue = cont
	}
	emitJump(fn, loop)
	fn.currentBlock = loop
	if loop != body {
		b.cond(fn, s.Cond, body, done)
		fn.currentBlock = body
	}
	fn.targets = &targets{
		tail:      fn.targets,
		_break:    done,
		_continue: cont,
	}
	b.stmt(fn, s.Body)
	fn.targets = fn.targets.tail
	emitJump(fn, cont)

	if s.Post != nil {
		fn.currentBlock = cont
		b.stmt(fn, s.Post)
		emitJump(fn, loop) // back-edge
	}
	fn.currentBlock = done
}

// forStmtGo122 emits to fn code for the for statement s, optionally
// labelled by label. s must define its variables.
//
// This allocates once per loop iteration. This is only correct in
// GoVersions >= go1.22.
func (b *builder) forStmtGo122(fn *Function, s *ast.ForStmt, label *lblock) {
	//     i_outer = alloc[T]
	//     *i_outer = ...init...        // under objects[i] = i_outer
	//     jump loop
	// loop:
	//     i = phi [head: i_outer, loop: i_next]
	//     ...cond...                   // under objects[i] = i
	//     if cond goto body else done
	// body:
	//     ...body...                   // under objects[i] = i (same as loop)
	//     jump post
	// post:
	//     tmp = *i
	//     i_next = alloc[T]
	//     *i_next = tmp
	//     ...post...                   // under objects[i] = i_next
	//     goto loop
	// done:

	init := s.Init.(*ast.AssignStmt)
	startingBlocks := len(fn.Blocks)

	pre := fn.currentBlock               // current block before starting
	loop := fn.newBasicBlock("for.loop") // target of back-edge
	body := fn.newBasicBlock("for.body")
	post := fn.newBasicBlock("for.post") // target of 'continue'
	done := fn.newBasicBlock("for.done") // target of 'break'

	// For each of the n loop variables, we create five SSA values,
	// outer, phi, next, load, and store in pre, loop, and post.
	// There is no limit on n.
	type loopVar struct {
		obj   *types.Var
		outer *Alloc
		phi   *Phi
		load  *UnOp
		next  *Alloc
		store *Store
	}
	vars := make([]loopVar, len(init.Lhs))
	for i, lhs := range init.Lhs {
		v := identVar(fn, lhs.(*ast.Ident))
		typ := fn.typ(v.Type())

		fn.currentBlock = pre
		outer := emitLocal(fn, typ, v.Pos(), v.Name())

		fn.currentBlock = loop
		phi := &Phi{Comment: v.Name()}
		phi.pos = v.Pos()
		phi.typ = outer.Type()
		fn.emit(phi)

		fn.currentBlock = post
		// If next is local, it reuses the address and zeroes the old value so
		// load before allocating next.
		load := emitLoad(fn, phi)
		next := emitLocal(fn, typ, v.Pos(), v.Name())
		store := emitStore(fn, next, load, token.NoPos)

		phi.Edges = []Value{outer, next} // pre edge is emitted before post edge.

		vars[i] = loopVar{v, outer, phi, load, next, store}
	}

	// ...init... under fn.objects[v] = i_outer
	fn.currentBlock = pre
	for _, v := range vars {
		fn.vars[v.obj] = v.outer
	}
	const isDef = false // assign to already-allocated outers
	b.assignStmt(fn, init.Lhs, init.Rhs, isDef)
	if label != nil {
		label._break = done
		label._continue = post
	}
	emitJump(fn, loop)

	// ...cond... under fn.objects[v] = i
	fn.currentBlock = loop
	for _, v := range vars {
		fn.vars[v.obj] = v.phi
	}
	if s.Cond != nil {
		b.cond(fn, s.Cond, body, done)
	} else {
		emitJump(fn, body)
	}

	// ...body... under fn.objects[v] = i
	fn.currentBlock = body
	fn.targets = &targets{
		tail:      fn.targets,
		_break:    done,
		_continue: post,
	}
	b.stmt(fn, s.Body)
	fn.targets = fn.targets.tail
	emitJump(fn, post)

	// ...post... under fn.objects[v] = i_next
	for _, v := range vars {
		fn.vars[v.obj] = v.next
	}
	fn.currentBlock = post
	if s.Post != nil {
		b.stmt(fn, s.Post)
	}
	emitJump(fn, loop) // back-edge
	fn.currentBlock = done

	// For each loop variable that does not escape,
	// (the common case), fuse its next cells into its
	// (local) outer cell as they have disjoint live ranges.
	//
	// It is sufficient to test whether i_next escapes,
	// because its Heap flag will be marked true if either
	// the cond or post expression causes i to escape
	// (because escape distributes over phi).
	var nlocals int
	for _, v := range vars {
		if !v.next.Heap {
			nlocals++
		}
	}
	if nlocals > 0 {
		replace := make(map[Value]Value, 2*nlocals)
		dead := make(map[Instruction]bool, 4*nlocals)
		for _, v := range vars {
			if !v.next.Heap {
				replace[v.next] = v.outer
				replace[v.phi] = v.outer
				dead[v.phi], dead[v.next], dead[v.load], dead[v.store] = true, true, true, true
			}
		}

		// Replace all uses of i_next and phi with i_outer.
		// Referrers have not been built for fn yet so only update Instruction operands.
		// We need only look within the blocks added by the loop.
		var operands []*Value // recycle storage
		for _, b := range fn.Blocks[startingBlocks:] {
			for _, instr := range b.Instrs {
				operands = instr.Operands(operands[:0])
				for _, ptr := range operands {
					k := *ptr
					if v := replace[k]; v != nil {
						*ptr = v
					}
				}
			}
		}

		// Remove instructions for phi, load, and store.
		// lift() will remove the unused i_next *Alloc.
		isDead := func(i Instruction) bool { return dead[i] }
		loop.Instrs = slices.DeleteFunc(loop.Instrs, isDead)
		post.Instrs = slices.DeleteFunc(post.Instrs, isDead)
	}
}

// rangeIndexed emits to fn the header for an integer-indexed loop
// over array, *array or slice value x.
// The v result is defined only if tv is non-nil.
// forPos is the position of the "for" token.
func (b *builder) rangeIndexed(fn *Function, x Value, tv types.Type, pos token.Pos) (k, v Value, loop, done *BasicBlock) {
	//
	//     length = len(x)
	//     index = -1
	// loop:                                     (target of continue)
	//     index++
	//     if index < length goto body else done
	// body:
	//     k = index
	//     v = x[index]
	//     ...body...
	//     jump loop
	// done:                                     (target of break)

	// Determine number of iterations.
	var length Value
	dt := typeparams.Deref(x.Type())
	if arr, ok := typeparams.CoreType(dt).(*types.Array); ok {
		// For array or *array, the number of iterations is
		// known statically thanks to the type.  We avoid a
		// data dependence upon x, permitting later dead-code
		// elimination if x is pure, static unrolling, etc.
		// Ranging over a nil *array may have >0 iterations.
		// We still generate code for x, in case it has effects.
		length = intConst(arr.Len())
	} else {
		// length = len(x).
		var c Call
		c.Call.Value = makeLen(x.Type())
		c.Call.Args = []Value{x}
		c.setType(tInt)
		length = fn.emit(&c)
	}

	index := emitLocal(fn, tInt, token.NoPos, "rangeindex")
	emitStore(fn, index, intConst(-1), pos)

	loop = fn.newBasicBlock("rangeindex.loop")
	emitJump(fn, loop)
	fn.currentBlock = loop

	incr := &BinOp{
		Op: token.ADD,
		X:  emitLoad(fn, index),
		Y:  vOne,
	}
	incr.setType(tInt)
	emitStore(fn, index, fn.emit(incr), pos)

	body := fn.newBasicBlock("rangeindex.body")
	done = fn.newBasicBlock("rangeindex.done")
	emitIf(fn, emitCompare(fn, token.LSS, incr, length, token.NoPos), body, done)
	fn.currentBlock = body

	k = emitLoad(fn, index)
	if tv != nil {
		switch t := typeparams.CoreType(x.Type()).(type) {
		case *types.Array:
			instr := &Index{
				X:     x,
				Index: k,
			}
			instr.setType(t.Elem())
			instr.setPos(x.Pos())
			v = fn.emit(instr)

		case *types.Pointer: // *array
			instr := &IndexAddr{
				X:     x,
				Index: k,
			}
			instr.setType(types.NewPointer(t.Elem().Underlying().(*types.Array).Elem()))
			instr.setPos(x.Pos())
			v = emitLoad(fn, fn.emit(instr))

		case *types.Slice:
			instr := &IndexAddr{
				X:     x,
				Index: k,
			}
			instr.setType(types.NewPointer(t.Elem()))
			instr.setPos(x.Pos())
			v = emitLoad(fn, fn.emit(instr))

		default:
			panic("rangeIndexed x:" + t.String())
		}
	}
	return
}

// rangeIter emits to fn the header for a loop using
// Range/Next/Extract to iterate over map or string value x.
// tk and tv are the types of the key/value results k and v, or nil
// if the respective component is not wanted.
func (b *builder) rangeIter(fn *Function, x Value, tk, tv types.Type, pos token.Pos) (k, v Value, loop, done *BasicBlock) {
	//
	//     it = range x
	// loop:                                   (target of continue)
	//     okv = next it                       (ok, key, value)
	//     ok = extract okv #0
	//     if ok goto body else done
	// body:
	//     k = extract okv #1
	//     v = extract okv #2
	//     ...body...
	//     jump loop
	// done:                                   (target of break)
	//

	if tk == nil {
		tk = tInvalid
	}
	if tv == nil {
		tv = tInvalid
	}

	rng := &Range{X: x}
	rng.setPos(pos)
	rng.setType(tRangeIter)
	it := fn.emit(rng)

	loop = fn.newBasicBlock("rangeiter.loop")
	emitJump(fn, loop)
	fn.currentBlock = loop

	okv := &Next{
		Iter:     it,
		IsString: isBasic(typeparams.CoreType(x.Type())),
	}
	okv.setType(types.NewTuple(
		varOk,
		newVar("k", tk),
		newVar("v", tv),
	))
	fn.emit(okv)

	body := fn.newBasicBlock("rangeiter.body")
	done = fn.newBasicBlock("rangeiter.done")
	emitIf(fn, emitExtract(fn, okv, 0), body, done)
	fn.currentBlock = body

	if tk != tInvalid {
		k = emitExtract(fn, okv, 1)
	}
	if tv != tInvalid {
		v = emitExtract(fn, okv, 2)
	}
	return
}

// rangeChan emits to fn the header for a loop that receives from
// channel x until it fails.
// tk is the channel's element type, or nil if the k result is
// not wanted
// pos is the position of the '=' or ':=' token.
func (b *builder) rangeChan(fn *Function, x Value, tk types.Type, pos token.Pos) (k Value, loop, done *BasicBlock) {
	//
	// loop:                                   (target of continue)
	//     ko = <-x                            (key, ok)
	//     ok = extract ko #1
	//     if ok goto body else done
	// body:
	//     k = extract ko #0
	//     ...body...
	//     goto loop
	// done:                                   (target of break)

	loop = fn.newBasicBlock("rangechan.loop")
	emitJump(fn, loop)
	fn.currentBlock = loop
	recv := &UnOp{
		Op:      token.ARROW,
		X:       x,
		CommaOk: true,
	}
	recv.setPos(pos)
	recv.setType(types.NewTuple(
		newVar("k", typeparams.CoreType(x.Type()).(*types.Chan).Elem()),
		varOk,
	))
	ko := fn.emit(recv)
	body := fn.newBasicBlock("rangechan.body")
	done = fn.newBasicBlock("rangechan.done")
	emitIf(fn, emitExtract(fn, ko, 1), body, done)
	fn.currentBlock = body
	if tk != nil {
		k = emitExtract(fn, ko, 0)
	}
	return
}

// rangeInt emits to fn the header for a range loop with an integer operand.
// tk is the key value's type, or nil if the k result is not wanted.
// pos is the position of the "for" token.
func (b *builder) rangeInt(fn *Function, x Value, tk types.Type, pos token.Pos) (k Value, loop, done *BasicBlock) {
	//
	//     iter = 0
	//     if 0 < x goto body else done
	// loop:                                   (target of continue)
	//     iter++
	//     if iter < x goto body else done
	// body:
	//     k = x
	//     ...body...
	//     jump loop
	// done:                                   (target of break)

	if isUntyped(x.Type()) {
		x = emitConv(fn, x, tInt)
	}

	T := x.Type()
	iter := emitLocal(fn, T, token.NoPos, "rangeint.iter")
	// x may be unsigned. Avoid initializing x to -1.

	body := fn.newBasicBlock("rangeint.body")
	done = fn.newBasicBlock("rangeint.done")
	emitIf(fn, emitCompare(fn, token.LSS, zeroConst(T), x, token.NoPos), body, done)

	loop = fn.newBasicBlock("rangeint.loop")
	fn.currentBlock = loop

	incr := &BinOp{
		Op: token.ADD,
		X:  emitLoad(fn, iter),
		Y:  emitConv(fn, vOne, T),
	}
	incr.setType(T)
	emitStore(fn, iter, fn.emit(incr), pos)
	emitIf(fn, emitCompare(fn, token.LSS, incr, x, token.NoPos), body, done)
	fn.currentBlock = body

	if tk != nil {
		// Integer types (int, uint8, etc.) are named and
		// we know that k is assignable to x when tk != nil.
		// This implies tk and T are identical so no conversion is needed.
		k = emitLoad(fn, iter)
	}

	return
}

// rangeStmt emits to fn code for the range statement s, optionally
// labelled by label.
func (b *builder) rangeStmt(fn *Function, s *ast.RangeStmt, label *lblock) {
	var tk, tv types.Type
	if s.Key != nil && !isBlankIdent(s.Key) {
		tk = fn.typeOf(s.Key)
	}
	if s.Value != nil && !isBlankIdent(s.Value) {
		tv = fn.typeOf(s.Value)
	}

	// create locals for s.Key and s.Value.
	createVars := func() {
		// Unlike a short variable declaration, a RangeStmt
		// using := never redeclares an existing variable; it
		// always creates a new one.
		if tk != nil {
			emitLocalVar(fn, identVar(fn, s.Key.(*ast.Ident)))
		}
		if tv != nil {
			emitLocalVar(fn, identVar(fn, s.Value.(*ast.Ident)))
		}
	}

	afterGo122 := versions.AtLeast(fn.goversion, versions.Go1_22)
	if s.Tok == token.DEFINE && !afterGo122 {
		// pre-go1.22: If iteration variables are defined (:=), this
		// occurs once outside the loop.
		createVars()
	}

	x := b.expr(fn, s.X)

	var k, v Value
	var loop, done *BasicBlock
	switch rt := typeparams.CoreType(x.Type()).(type) {
	case *types.Slice, *types.Array, *types.Pointer: // *array
		k, v, loop, done = b.rangeIndexed(fn, x, tv, s.For)

	case *types.Chan:
		k, loop, done = b.rangeChan(fn, x, tk, s.For)

	case *types.Map:
		k, v, loop, done = b.rangeIter(fn, x, tk, tv, s.For)

	case *types.Basic:
		switch {
		case rt.Info()&types.IsString != 0:
			k, v, loop, done = b.rangeIter(fn, x, tk, tv, s.For)

		case rt.Info()&types.IsInteger != 0:
			k, loop, done = b.rangeInt(fn, x, tk, s.For)

		default:
			panic("Cannot range over basic type: " + rt.String())
		}

	case *types.Signature:
		// Special case rewrite (fn.goversion >= go1.23):
		// 	for x := range f { ... }
		// into
		// 	f(func(x T) bool { ... })
		b.rangeFunc(fn, x, s, label)
		return

	default:
		panic("Cannot range over: " + rt.String())
	}

	if s.Tok == token.DEFINE && afterGo122 {
		// go1.22: If iteration variables are defined (:=), this occurs inside the loop.
		createVars()
	}

	// Evaluate both LHS expressions before we update either.
	var kl, vl lvalue
	if tk != nil {
		kl = b.addr(fn, s.Key, false) // non-escaping
	}
	if tv != nil {
		vl = b.addr(fn, s.Value, false) // non-escaping
	}
	if tk != nil {
		kl.store(fn, k)
	}
	if tv != nil {
		vl.store(fn, v)
	}

	if label != nil {
		label._break = done
		label._continue = loop
	}

	fn.targets = &targets{
		tail:      fn.targets,
		_break:    done,
		_continue: loop,
	}
	b.stmt(fn, s.Body)
	fn.targets = fn.targets.tail
	emitJump(fn, loop) // back-edge
	fn.currentBlock = done
}

// rangeFunc emits to fn code for the range-over-func rng.Body of the iterator
// function x, optionally labelled by label. It creates a new anonymous function
// yield for rng and builds the function.
func (b *builder) rangeFunc(fn *Function, x Value, rng *ast.RangeStmt, label *lblock) {
	// Consider the SSA code for the outermost range-over-func in fn:
	//
	//   func fn(...) (ret R) {
	//     ...
	//     for k, v = range x {
	// 	     ...
	//     }
	//     ...
	//   }
	//
	// The code emitted into fn will look something like this.
	//
	// loop:
	//     jump := READY
	//     y := make closure yield [ret, deferstack, jump, k, v]
	//     x(y)
	//     switch jump {
	//        [see resuming execution]
	//     }
	//     goto done
	// done:
	//     ...
	//
	// where yield is a new synthetic yield function:
	//
	// func yield(_k tk, _v tv) bool
	//   free variables: [ret, stack, jump, k, v]
	// {
	//    entry:
	//      if jump != READY then goto invalid else valid
	//    invalid:
	//      panic("iterator called when it is not in a ready state")
	//    valid:
	//      jump = BUSY
	//      k = _k
	//      v = _v
	//    ...
	//    cont:
	//      jump = READY
	//      return true
	// }
	//
	// Yield state:
	//
	// Each range loop has an associated jump variable that records
	// the state of the iterator. A yield function is initially
	// in a READY (0) and callable state.  If the yield function is called
	// and is not in READY state, it panics. When it is called in a callable
	// state, it becomes BUSY. When execution reaches the end of the body
	// of the loop (or a continue statement targeting the loop is executed),
	// the yield function returns true and resumes being in a READY state.
	// After the iterator function x(y) returns, then if the yield function
	// is in a READY state, the yield enters the DONE state.
	//
	// Each lowered control statement (break X, continue X, goto Z, or return)
	// that exits the loop sets the variable to a unique positive EXIT value,
	// before returning false from the yield function.
	//
	// If the yield function returns abruptly due to a panic or GoExit,
	// it remains in a BUSY state. The generated code asserts that, after
	// the iterator call x(y) returns normally, the jump variable state
	// is DONE.
	//
	// Resuming execution:
	//
	// The code generated for the range statement checks the jump
	// variable to determine how to resume execution.
	//
	//    switch jump {
	//    case BUSY:  panic("...")
	//    case DONE:  goto done
	//    case READY: state = DONE; goto done
	//    case 123:   ... // action for exit 123.
	//    case 456:   ... // action for exit 456.
	//    ...
	//    }
	//
	// Forward goto statements within a yield are jumps to labels that
	// have not yet been traversed in fn. They may be in the Body of the
	// function. What we emit for these is:
	//
	//    goto target
	//  target:
	//    ...
	//
	// We leave an unresolved exit in yield.exits to check at the end
	// of building yield if it encountered target in the body. If it
	// encountered target, no additional work is required. Otherwise,
	// the yield emits a new early exit in the basic block for target.
	// We expect that blockopt will fuse the early exit into the case
	// block later. The unresolved exit is then added to yield.parent.exits.

	loop := fn.newBasicBlock("rangefunc.loop")
	done := fn.newBasicBlock("rangefunc.done")

	// These are targets within y.
	fn.targets = &targets{
		tail:   fn.targets,
		_break: done,
		// _continue is within y.
	}
	if label != nil {
		label._break = done
		// _continue is within y
	}

	emitJump(fn, loop)
	fn.currentBlock = loop

	// loop:
	//     jump := READY

	anonIdx := len(fn.AnonFuncs)

	jump := newVar(fmt.Sprintf("jump$%d", anonIdx+1), tInt)
	emitLocalVar(fn, jump) // zero value is READY

	xsig := typeparams.CoreType(x.Type()).(*types.Signature)
	ysig := typeparams.CoreType(xsig.Params().At(0).Type()).(*types.Signature)

	/* synthetic yield function for body of range-over-func loop */
	y := &Function{
		name:           fmt.Sprintf("%s$%d", fn.Name(), anonIdx+1),
		Signature:      ysig,
		Synthetic:      "range-over-func yield",
		pos:            rng.Range,
		parent:         fn,
		anonIdx:        int32(len(fn.AnonFuncs)),
		Pkg:            fn.Pkg,
		Prog:           fn.Prog,
		syntax:         rng,
		info:           fn.info,
		goversion:      fn.goversion,
		build:          (*builder).buildYieldFunc,
		topLevelOrigin: nil,
		typeparams:     fn.typeparams,
		typeargs:       fn.typeargs,
		subst:          fn.subst,
		jump:           jump,
		deferstack:     fn.deferstack,
		returnVars:     fn.returnVars, // use the parent's return variables
		uniq:           fn.uniq,       // start from parent's unique values
	}

	// If the RangeStmt has a label, this is how it is passed to buildYieldFunc.
	if label != nil {
		y.lblocks = map[*types.Label]*lblock{label.label: nil}
	}
	fn.AnonFuncs = append(fn.AnonFuncs, y)

	// Build y immediately. It may:
	// * cause fn's locals to escape, and
	// * create new exit nodes in exits.
	// (y is not marked 'built' until the end of the enclosing FuncDecl.)
	unresolved := len(fn.exits)
	y.build(b, y)
	fn.uniq = y.uniq // resume after y's unique values

	// Emit the call of y.
	//   c := MakeClosure y
	//   x(c)
	c := &MakeClosure{Fn: y}
	c.setType(ysig)
	for _, fv := range y.FreeVars {
		c.Bindings = append(c.Bindings, fv.outer)
		fv.outer = nil
	}
	fn.emit(c)
	call := Call{
		Call: CallCommon{
			Value: x,
			Args:  []Value{c},
			pos:   token.NoPos,
		},
	}
	call.setType(xsig.Results())
	fn.emit(&call)

	exits := fn.exits[unresolved:]
	b.buildYieldResume(fn, jump, exits, done)

	emitJump(fn, done)
	fn.currentBlock = done
	// pop the stack for the range-over-func
	fn.targets = fn.targets.tail
}

// buildYieldResume emits to fn code for how to resume execution once a call to
// the iterator function over the yield function returns x(y). It does this by building
// a switch over the value of jump for when it is READY, BUSY, or EXIT(id).
func (b *builder) buildYieldResume(fn *Function, jump *types.Var, exits []*exit, done *BasicBlock) {
	//    v := *jump
	//    switch v {
	//    case BUSY:    panic("...")
	//    case READY:   jump = DONE; goto done
	//    case EXIT(a): ...
	//    case EXIT(b): ...
	//    ...
	//    }
	v := emitLoad(fn, fn.lookup(jump, false))

	// case BUSY: panic("...")
	isbusy := fn.newBasicBlock("rangefunc.resume.busy")
	ifready := fn.newBasicBlock("rangefunc.resume.ready.check")
	emitIf(fn, emitCompare(fn, token.EQL, v, jBusy, token.NoPos), isbusy, ifready)
	fn.currentBlock = isbusy
	fn.emit(&Panic{
		X: emitConv(fn, stringConst("iterator call did not preserve panic"), tEface),
	})
	fn.currentBlock = ifready

	// case READY: jump = DONE; goto done
	isready := fn.newBasicBlock("rangefunc.resume.ready")
	ifexit := fn.newBasicBlock("rangefunc.resume.exits")
	emitIf(fn, emitCompare(fn, token.EQL, v, jReady, token.NoPos), isready, ifexit)
	fn.currentBlock = isready
	storeVar(fn, jump, jDone, token.NoPos)
	emitJump(fn, done)
	fn.currentBlock = ifexit

	for _, e := range exits {
		id := intConst(e.id)

		//  case EXIT(id): { /* do e */ }
		cond := emitCompare(fn, token.EQL, v, id, e.pos)
		matchb := fn.newBasicBlock("rangefunc.resume.match")
		cndb := fn.newBasicBlock("rangefunc.resume.cnd")
		emitIf(fn, cond, matchb, cndb)
		fn.currentBlock = matchb

		// Cases to fill in the { /* do e */ } bit.
		switch {
		case e.label != nil: // forward goto?
			// case EXIT(id): goto lb // label
			lb := fn.lblockOf(e.label)
			// Do not mark lb as resolved.
			// If fn does not contain label, lb remains unresolved and
			// fn must itself be a range-over-func function. lb will be:
			//   lb:
			//     fn.jump = id
			//     return false
			emitJump(fn, lb._goto)

		case e.to != fn: // e jumps to an ancestor of fn?
			// case EXIT(id): { fn.jump = id; return false }
			// fn is a range-over-func function.
			storeVar(fn, fn.jump, id, token.NoPos)
			fn.emit(&Return{Results: []Value{vFalse}, pos: e.pos})

		case e.block == nil && e.label == nil: // return from fn?
			// case EXIT(id): { return ... }
			fn.emit(new(RunDefers))
			results := make([]Value, len(fn.results))
			for i, r := range fn.results {
				results[i] = emitLoad(fn, r)
			}
			fn.emit(&Return{Results: results, pos: e.pos})

		case e.block != nil:
			// case EXIT(id): goto block
			emitJump(fn, e.block)

		default:
			panic("unreachable")
		}
		fn.currentBlock = cndb
	}
}

// stmt lowers statement s to SSA form, emitting code to fn.
func (b *builder) stmt(fn *Function, _s ast.Stmt) {
	// The label of the current statement.  If non-nil, its _goto
	// target is always set; its _break and _continue are set only
	// within the body of switch/typeswitch/select/for/range.
	// It is effectively an additional default-nil parameter of stmt().
	var label *lblock
start:
	switch s := _s.(type) {
	case *ast.EmptyStmt:
		// ignore.  (Usually removed by gofmt.)

	case *ast.DeclStmt: // Con, Var or Typ
		d := s.Decl.(*ast.GenDecl)
		if d.Tok == token.VAR {
			for _, spec := range d.Specs {
				if vs, ok := spec.(*ast.ValueSpec); ok {
					b.localValueSpec(fn, vs)
				}
			}
		}

	case *ast.LabeledStmt:
		if s.Label.Name == "_" {
			// Blank labels can't be the target of a goto, break,
			// or continue statement, so we don't need a new block.
			_s = s.Stmt
			goto start
		}
		label = fn.lblockOf(fn.label(s.Label))
		label.resolved = true
		emitJump(fn, label._goto)
		fn.currentBlock = label._goto
		_s = s.Stmt
		goto start // effectively: tailcall stmt(fn, s.Stmt, label)

	case *ast.ExprStmt:
		b.expr(fn, s.X)

	case *ast.SendStmt:
		chtyp := typeparams.CoreType(fn.typeOf(s.Chan)).(*types.Chan)
		fn.emit(&Send{
			Chan: b.expr(fn, s.Chan),
			X:    emitConv(fn, b.expr(fn, s.Value), chtyp.Elem()),
			pos:  s.Arrow,
		})

	case *ast.IncDecStmt:
		op := token.ADD
		if s.Tok == token.DEC {
			op = token.SUB
		}
		loc := b.addr(fn, s.X, false)
		b.assignOp(fn, loc, NewConst(constant.MakeInt64(1), loc.typ()), op, s.Pos())

	case *ast.AssignStmt:
		switch s.Tok {
		case token.ASSIGN, token.DEFINE:
			b.assignStmt(fn, s.Lhs, s.Rhs, s.Tok == token.DEFINE)

		default: // +=, etc.
			op := s.Tok + token.ADD - token.ADD_ASSIGN
			b.assignOp(fn, b.addr(fn, s.Lhs[0], false), b.expr(fn, s.Rhs[0]), op, s.Pos())
		}

	case *ast.GoStmt:
		// The "intrinsics" new/make/len/cap are forbidden here.
		// panic is treated like an ordinary function call.
		v := Go{pos: s.Go}
		b.setCall(fn, s.Call, &v.Call)
		fn.emit(&v)

	case *ast.DeferStmt:
		// The "intrinsics" new/make/len/cap are forbidden here.
		// panic is treated like an ordinary function call.
		deferstack := emitLoad(fn, fn.lookup(fn.deferstack, false))
		v := Defer{pos: s.Defer, DeferStack: deferstack}
		b.setCall(fn, s.Call, &v.Call)
		fn.emit(&v)

		// A deferred call can cause recovery from panic,
		// and control resumes at the Recover block.
		createRecoverBlock(fn.source)

	case *ast.ReturnStmt:
		b.returnStmt(fn, s)

	case *ast.BranchStmt:
		b.branchStmt(fn, s)

	case *ast.BlockStmt:
		b.stmtList(fn, s.List)

	case *ast.IfStmt:
		if s.Init != nil {
			b.stmt(fn, s.Init)
		}
		then := fn.newBasicBlock("if.then")
		done := fn.newBasicBlock("if.done")
		els := done
		if s.Else != nil {
			els = fn.newBasicBlock("if.else")
		}
		b.cond(fn, s.Cond, then, els)
		fn.currentBlock = then
		b.stmt(fn, s.Body)
		emitJump(fn, done)

		if s.Else != nil {
			fn.currentBlock = els
			b.stmt(fn, s.Else)
			emitJump(fn, done)
		}

		fn.currentBlock = done

	case *ast.SwitchStmt:
		b.switchStmt(fn, s, label)

	case *ast.TypeSwitchStmt:
		b.typeSwitchStmt(fn, s, label)

	case *ast.SelectStmt:
		b.selectStmt(fn, s, label)

	case *ast.ForStmt:
		b.forStmt(fn, s, label)

	case *ast.RangeStmt:
		b.rangeStmt(fn, s, label)

	default:
		panic(fmt.Sprintf("unexpected statement kind: %T", s))
	}
}

func (b *builder) branchStmt(fn *Function, s *ast.BranchStmt) {
	var block *BasicBlock
	if s.Label == nil {
		block = targetedBlock(fn, s.Tok)
	} else {
		target := fn.label(s.Label)
		block = labelledBlock(fn, target, s.Tok)
		if block == nil { // forward goto
			lb := fn.lblockOf(target)
			block = lb._goto // jump to lb._goto
			if fn.jump != nil {
				// fn is a range-over-func and the goto may exit fn.
				// Create an exit and resolve it at the end of
				// builder.buildYieldFunc.
				labelExit(fn, target, s.Pos())
			}
		}
	}
	to := block.parent

	if to == fn {
		emitJump(fn, block)
	} else { // break outside of fn.
		// fn must be a range-over-func
		e := blockExit(fn, block, s.Pos())
		storeVar(fn, fn.jump, intConst(e.id), e.pos)
		fn.emit(&Return{Results: []Value{vFalse}, pos: e.pos})
	}
	fn.currentBlock = fn.newBasicBlock("unreachable")
}

func (b *builder) returnStmt(fn *Function, s *ast.ReturnStmt) {
	var results []Value

	sig := fn.source.Signature // signature of the enclosing source function

	// Convert return operands to result type.
	if len(s.Results) == 1 && sig.Results().Len() > 1 {
		// Return of one expression in a multi-valued function.
		tuple := b.exprN(fn, s.Results[0])
		ttuple := tuple.Type().(*types.Tuple)
		for i, n := 0, ttuple.Len(); i < n; i++ {
			results = append(results,
				emitConv(fn, emitExtract(fn, tuple, i),
					sig.Results().At(i).Type()))
		}
	} else {
		// 1:1 return, or no-arg return in non-void function.
		for i, r := range s.Results {
			v := emitConv(fn, b.expr(fn, r), sig.Results().At(i).Type())
			results = append(results, v)
		}
	}

	// Store the results.
	for i, r := range results {
		var result Value // fn.source.result[i] conceptually
		if fn == fn.source {
			result = fn.results[i]
		} else { // lookup needed?
			result = fn.lookup(fn.returnVars[i], false)
		}
		emitStore(fn, result, r, s.Return)
	}

	if fn.jump != nil {
		// Return from body of a range-over-func.
		// The return statement is syntactically within the loop,
		// but the generated code is in the 'switch jump {...}' after it.
		e := returnExit(fn, s.Pos())
		storeVar(fn, fn.jump, intConst(e.id), e.pos)
		fn.emit(&Return{Results: []Value{vFalse}, pos: e.pos})
		fn.currentBlock = fn.newBasicBlock("unreachable")
		return
	}

	// Run function calls deferred in this
	// function when explicitly returning from it.
	fn.emit(new(RunDefers))
	// Reload (potentially) named result variables to form the result tuple.
	results = results[:0]
	for _, nr := range fn.results {
		results = append(results, emitLoad(fn, nr))
	}
	fn.emit(&Return{Results: results, pos: s.Return})
	fn.currentBlock = fn.newBasicBlock("unreachable")
}

// A buildFunc is a strategy for building the SSA body for a function.
type buildFunc = func(*builder, *Function)

// iterate causes all created but unbuilt functions to be built. As
// this may create new methods, the process is iterated until it
// converges.
//
// Waits for any dependencies to finish building.
func (b *builder) iterate() {
	for ; b.finished < len(b.fns); b.finished++ {
		fn := b.fns[b.finished]
		b.buildFunction(fn)
	}

	b.buildshared.markDone()
	b.buildshared.wait()
}

// buildFunction builds SSA code for the body of function fn.  Idempotent.
func (b *builder) buildFunction(fn *Function) {
	if fn.build != nil {
		assert(fn.parent == nil, "anonymous functions should not be built by buildFunction()")

		if fn.Prog.mode&LogSource != 0 {
			defer logStack("build %s @ %s", fn, fn.Prog.Fset.Position(fn.pos))()
		}
		fn.build(b, fn)
		fn.done()
	}
}

// buildParamsOnly builds fn.Params from fn.Signature, but does not build fn.Body.
func (b *builder) buildParamsOnly(fn *Function) {
	// For external (C, asm) functions or functions loaded from
	// export data, we must set fn.Params even though there is no
	// body code to reference them.
	if recv := fn.Signature.Recv(); recv != nil {
		fn.addParamVar(recv)
	}
	params := fn.Signature.Params()
	for i, n := 0, params.Len(); i < n; i++ {
		fn.addParamVar(params.At(i))
	}

	// clear out other function state (keep consistent with finishBody)
	fn.subst = nil
}

// buildFromSyntax builds fn.Body from fn.syntax, which must be non-nil.
func (b *builder) buildFromSyntax(fn *Function) {
	var (
		recvField *ast.FieldList
		body      *ast.BlockStmt
		functype  *ast.FuncType
	)
	switch syntax := fn.syntax.(type) {
	case *ast.FuncDecl:
		functype = syntax.Type
		recvField = syntax.Recv
		body = syntax.Body
		if body == nil {
			b.buildParamsOnly(fn) // no body (non-Go function)
			return
		}
	case *ast.FuncLit:
		functype = syntax.Type
		body = syntax.Body
	case nil:
		panic("no syntax")
	default:
		panic(syntax) // unexpected syntax
	}
	fn.source = fn
	fn.startBody()
	fn.createSyntacticParams(recvField, functype)
	fn.createDeferStack()
	b.stmt(fn, body)
	if cb := fn.currentBlock; cb != nil && (cb == fn.Blocks[0] || cb == fn.Recover || cb.Preds != nil) {
		// Control fell off the end of the function's body block.
		//
		// Block optimizations eliminate the current block, if
		// unreachable.  It is a builder invariant that
		// if this no-arg return is ill-typed for
		// fn.Signature.Results, this block must be
		// unreachable.  The sanity checker checks this.
		fn.emit(new(RunDefers))
		fn.emit(new(Return))
	}
	fn.finishBody()
}

// buildYieldFunc builds the body of the yield function created
// from a range-over-func *ast.RangeStmt.
func (b *builder) buildYieldFunc(fn *Function) {
	// See builder.rangeFunc for detailed documentation on how fn is set up.
	//
	// In pseudo-Go this roughly builds:
	// func yield(_k tk, _v tv) bool {
	// 	   if jump != READY { panic("yield function called after range loop exit") }
	//     jump = BUSY
	//     k, v = _k, _v // assign the iterator variable (if needed)
	//     ... // rng.Body
	//   continue:
	//     jump = READY
	//     return true
	// }
	s := fn.syntax.(*ast.RangeStmt)
	fn.source = fn.parent.source
	fn.startBody()
	params := fn.Signature.Params()
	for v := range params.Variables() {
		fn.addParamVar(v)
	}

	// Initial targets
	ycont := fn.newBasicBlock("yield-continue")
	// lblocks is either {} or is {label: nil} where label is the label of syntax.
	for label := range fn.lblocks {
		fn.lblocks[label] = &lblock{
			label:     label,
			resolved:  true,
			_goto:     ycont,
			_continue: ycont,
			// `break label` statement targets fn.parent.targets._break
		}
	}
	fn.targets = &targets{
		tail:      fn.targets,
		_continue: ycont,
		// `break` statement targets fn.parent.targets._break.
	}

	// continue:
	//   jump = READY
	//   return true
	saved := fn.currentBlock
	fn.currentBlock = ycont
	storeVar(fn, fn.jump, jReady, s.Body.Rbrace)
	// A yield function's own deferstack is always empty, so rundefers is not needed.
	fn.emit(&Return{Results: []Value{vTrue}, pos: token.NoPos})

	// Emit header:
	//
	//   if jump != READY { panic("yield iterator accessed after exit") }
	//   jump = BUSY
	//   k, v = _k, _v
	fn.currentBlock = saved
	yloop := fn.newBasicBlock("yield-loop")
	invalid := fn.newBasicBlock("yield-invalid")

	jumpVal := emitLoad(fn, fn.lookup(fn.jump, true))
	emitIf(fn, emitCompare(fn, token.EQL, jumpVal, jReady, token.NoPos), yloop, invalid)
	fn.currentBlock = invalid
	fn.emit(&Panic{
		X: emitConv(fn, stringConst("yield function called after range loop exit"), tEface),
	})

	fn.currentBlock = yloop
	storeVar(fn, fn.jump, jBusy, s.Body.Rbrace)

	// Initialize k and v from params.
	var tk, tv types.Type
	if s.Key != nil && !isBlankIdent(s.Key) {
		tk = fn.typeOf(s.Key) // fn.parent.typeOf is identical
	}
	if s.Value != nil && !isBlankIdent(s.Value) {
		tv = fn.typeOf(s.Value)
	}
	if s.Tok == token.DEFINE {
		if tk != nil {
			emitLocalVar(fn, identVar(fn, s.Key.(*ast.Ident)))
		}
		if tv != nil {
			emitLocalVar(fn, identVar(fn, s.Value.(*ast.Ident)))
		}
	}
	var k, v Value
	if len(fn.Params) > 0 {
		k = fn.Params[0]
	}
	if len(fn.Params) > 1 {
		v = fn.Params[1]
	}
	var kl, vl lvalue
	if tk != nil {
		kl = b.addr(fn, s.Key, false) // non-escaping
	}
	if tv != nil {
		vl = b.addr(fn, s.Value, false) // non-escaping
	}
	if tk != nil {
		kl.store(fn, k)
	}
	if tv != nil {
		vl.store(fn, v)
	}

	// Build the body of the range loop.
	b.stmt(fn, s.Body)
	if cb := fn.currentBlock; cb != nil && (cb == fn.Blocks[0] || cb == fn.Recover || cb.Preds != nil) {
		// Control fell off the end of the function's body block.
		// Block optimizations eliminate the current block, if
		// unreachable.
		emitJump(fn, ycont)
	}
	// pop the stack for the yield function
	fn.targets = fn.targets.tail

	// Clean up exits and promote any unresolved exits to fn.parent.
	for _, e := range fn.exits {
		if e.label != nil {
			lb := fn.lblocks[e.label]
			if lb.resolved {
				// label was resolved. Do not turn lb into an exit.
				// e does not need to be handled by the parent.
				continue
			}

			// _goto becomes an exit.
			//   _goto:
			//     jump = id
			//     return false
			fn.currentBlock = lb._goto
			id := intConst(e.id)
			storeVar(fn, fn.jump, id, e.pos)
			fn.emit(&Return{Results: []Value{vFalse}, pos: e.pos})
		}

		if e.to != fn { // e needs to be handled by the parent too.
			fn.parent.exits = append(fn.parent.exits, e)
		}
	}

	fn.finishBody()
}

// addMakeInterfaceType records non-interface type t as the type of
// the operand a MakeInterface operation, for [Program.RuntimeTypes].
//
// Acquires prog.makeInterfaceTypesMu.
func addMakeInterfaceType(prog *Program, t types.Type) {
	prog.makeInterfaceTypesMu.Lock()
	defer prog.makeInterfaceTypesMu.Unlock()
	if prog.makeInterfaceTypes == nil {
		prog.makeInterfaceTypes = make(map[types.Type]unit)
	}
	prog.makeInterfaceTypes[t] = unit{}
}

// Build calls Package.Build for each package in prog.
// Building occurs in parallel unless the BuildSerially mode flag was set.
//
// Build is intended for whole-program analysis; a typical compiler
// need only build a single package.
//
// Build is idempotent and thread-safe.
func (prog *Program) Build() {
	var wg sync.WaitGroup
	for _, p := range prog.packages {
		if prog.mode&BuildSerially != 0 {
			p.Build()
		} else {
			wg.Add(1)
			cpuLimit <- unit{} // acquire a token
			go func(p *Package) {
				p.Build()
				wg.Done()
				<-cpuLimit // release a token
			}(p)
		}
	}
	wg.Wait()
}

// cpuLimit is a counting semaphore to limit CPU parallelism.
var cpuLimit = make(chan unit, runtime.GOMAXPROCS(0))

// Build builds SSA code for all functions and vars in package p.
//
// CreatePackage must have been called for all of p's direct imports
// (and hence its direct imports must have been error-free). It is not
// necessary to call CreatePackage for indirect dependencies.
// Functions will be created for all necessary methods in those
// packages on demand.
//
// Build is idempotent and thread-safe.
func (p *Package) Build() { p.buildOnce.Do(p.build) }

func (p *Package) build() {
	if p.info == nil {
		return // synthetic package, e.g. "testmain"
	}
	if p.Prog.mode&LogSource != 0 {
		defer logStack("build %s", p)()
	}

	b := builder{fns: p.created}
	b.iterate()

	// We no longer need transient information: ASTs or go/types deductions.
	p.info = nil
	p.created = nil
	p.files = nil
	p.initVersion = nil

	if p.Prog.mode&SanityCheckFunctions != 0 {
		sanityCheckPackage(p)
	}
}

// buildPackageInit builds fn.Body for the synthetic package initializer.
func (b *builder) buildPackageInit(fn *Function) {
	p := fn.Pkg
	fn.startBody()

	var done *BasicBlock

	if p.Prog.mode&BareInits == 0 {
		// Make init() skip if package is already initialized.
		initguard := p.Var("init$guard")
		doinit := fn.newBasicBlock("init.start")
		done = fn.newBasicBlock("init.done")
		emitIf(fn, emitLoad(fn, initguard), done, doinit)
		fn.currentBlock = doinit
		emitStore(fn, initguard, vTrue, token.NoPos)

		// Call the init() function of each package we import.
		for _, pkg := range p.Pkg.Imports() {
			prereq := p.Prog.packages[pkg]
			if prereq == nil {
				panic(fmt.Sprintf("Package(%q).Build(): unsatisfied import: Program.CreatePackage(%q) was not called", p.Pkg.Path(), pkg.Path()))
			}
			var v Call
			v.Call.Value = prereq.init
			v.Call.pos = fn.pos
			v.setType(types.NewTuple())
			fn.emit(&v)
		}
	}

	// Initialize package-level vars in correct order.
	if len(p.info.InitOrder) > 0 && len(p.files) == 0 {
		panic("no source files provided for package. cannot initialize globals")
	}

	for _, varinit := range p.info.InitOrder {
		if fn.Prog.mode&LogSource != 0 {
			fmt.Fprintf(os.Stderr, "build global initializer %v @ %s\n",
				varinit.Lhs, p.Prog.Fset.Position(varinit.Rhs.Pos()))
		}
		// Initializers for global vars are evaluated in dependency
		// order, but may come from arbitrary files of the package
		// with different versions, so we transiently update
		// fn.goversion for each one. (Since init is a synthetic
		// function it has no syntax of its own that needs a version.)
		fn.goversion = p.initVersion[varinit.Rhs]
		if len(varinit.Lhs) == 1 {
			// 1:1 initialization: var x, y = a(), b()
			var lval lvalue
			if v := varinit.Lhs[0]; v.Name() != "_" {
				lval = &address{addr: p.objects[v].(*Global), pos: v.Pos()}
			} else {
				lval = blank{}
			}
			b.assign(fn, lval, varinit.Rhs, true, nil)
		} else {
			// n:1 initialization: var x, y :=  f()
			tuple := b.exprN(fn, varinit.Rhs)
			for i, v := range varinit.Lhs {
				if v.Name() == "_" {
					continue
				}
				emitStore(fn, p.objects[v].(*Global), emitExtract(fn, tuple, i), v.Pos())
			}
		}
	}

	// The rest of the init function is synthetic:
	// no syntax, info, goversion.
	fn.info = nil
	fn.goversion = ""

	// Call all of the declared init() functions in source order.
	for _, file := range p.files {
		for _, decl := range file.Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok {
				id := decl.Name
				if !isBlankIdent(id) && id.Name == "init" && decl.Recv == nil {
					declaredInit := p.objects[p.info.Defs[id]].(*Function)
					var v Call
					v.Call.Value = declaredInit
					v.setType(types.NewTuple())
					p.init.emit(&v)
				}
			}
		}
	}

	// Finish up init().
	if p.Prog.mode&BareInits == 0 {
		emitJump(fn, done)
		fn.currentBlock = done
	}
	fn.emit(new(Return))
	fn.finishBody()
}


================================================
FILE: go/ssa/builder_generic_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"bytes"
	"fmt"
	"go/parser"
	"go/token"
	"reflect"
	"sort"
	"testing"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/expect"
)

// TestGenericBodies tests that bodies of generic functions and methods containing
// different constructs can be built in BuilderMode(0).
//
// Each test specifies the contents of package containing a single go file.
// Each call print(arg0, arg1, ...) to the builtin print function
// in ssa is correlated a comment at the end of the line of the form:
//
//	//@ types(a, b, c)
//
// where a, b and c are the types of the arguments to the print call
// serialized using go/types.Type.String().
// See x/tools/internal/expect for details on the syntax.
func TestGenericBodies(t *testing.T) {
	for _, content := range []string{
		`
		package p00

		func f(x int) {
			var i interface{}
			print(i, 0) //@ types("interface{}", int)
			print()     //@ types()
			print(x)    //@ types(int)
		}
		`,
		`
		package p01

		func f[T any](x T) {
			print(x) //@ types(T)
		}
		`,
		`
		package p02

		func f[T ~int]() {
			var x T
			print(x) //@ types(T)
		}
		`,
		`
		package p03

		func a[T ~[4]byte](x T) {
			for k, v := range x {
				print(x, k, v) //@ types(T, int, byte)
			}
		}
		func b[T ~*[4]byte](x T) {
			for k, v := range x {
				print(x, k, v) //@ types(T, int, byte)
			}
		}
		func c[T ~[]byte](x T) {
			for k, v := range x {
				print(x, k, v) //@ types(T, int, byte)
			}
		}
		func d[T ~string](x T) {
			for k, v := range x {
				print(x, k, v) //@ types(T, int, rune)
			}
		}
		func e[T ~map[int]string](x T) {
			for k, v := range x {
				print(x, k, v) //@ types(T, int, string)
			}
		}
		func f[T ~chan string](x T) {
			for v := range x {
				print(x, v) //@ types(T, string)
			}
		}

		func From() {
			type A [4]byte
			print(a[A]) //@ types("func(x p03.A)")

			type B *[4]byte
			print(b[B]) //@ types("func(x p03.B)")

			type C []byte
			print(c[C]) //@ types("func(x p03.C)")

			type D string
			print(d[D]) //@ types("func(x p03.D)")

			type E map[int]string
			print(e[E]) //@ types("func(x p03.E)")

			type F chan string
			print(f[F]) //@ types("func(x p03.F)")
		}
		`,
		`
		package p05

		func f[S any, T ~chan S](x T) {
			for v := range x {
				print(x, v) //@ types(T, S)
			}
		}

		func From() {
			type F chan string
			print(f[string, F]) //@ types("func(x p05.F)")
		}
		`,
		`
		package p06

		func fibonacci[T ~chan int](c, quit T) {
			x, y := 0, 1
			for {
				select {
				case c <- x:
					x, y = y, x+y
				case <-quit:
					print(c, quit, x, y) //@ types(T, T, int, int)
					return
				}
			}
		}
		func start[T ~chan int](c, quit T) {
			go func() {
				for i := 0; i < 10; i++ {
					print(<-c) //@ types(int)
				}
				quit <- 0
			}()
		}
		func From() {
			type F chan int
			c := make(F)
			quit := make(F)
			print(start[F], c, quit)     //@ types("func(c p06.F, quit p06.F)", "p06.F", "p06.F")
			print(fibonacci[F], c, quit) //@ types("func(c p06.F, quit p06.F)", "p06.F", "p06.F")
		}
		`,
		`
		package p07

		func f[T ~struct{ x int; y string }](i int) T {
			u := []T{ T{0, "lorem"},  T{1, "ipsum"}}
			return u[i]
		}
		func From() {
			type S struct{ x int; y string }
			print(f[S])     //@ types("func(i int) p07.S")
		}
		`,
		`
		package p08

		func f[T ~[4]int8](x T, l, h int) []int8 {
			return x[l:h]
		}
		func g[T ~*[4]int16](x T, l, h int) []int16 {
			return x[l:h]
		}
		func h[T ~[]int32](x T, l, h int) T {
			return x[l:h]
		}
		func From() {
			type F [4]int8
			type G *[4]int16
			type H []int32
			print(f[F](F{}, 0, 0))  //@ types("[]int8")
			print(g[G](nil, 0, 0)) //@ types("[]int16")
			print(h[H](nil, 0, 0)) //@ types("p08.H")
		}
		`,
		`
		package p09

		func h[E any, T ~[]E](x T, l, h int) []E {
			s := x[l:h]
			print(s) //@ types("T")
			return s
		}
		func From() {
			type H []int32
			print(h[int32, H](nil, 0, 0)) //@ types("[]int32")
		}
		`,
		`
		package p10

		// Test "make" builtin with different forms on core types and
		// when capacities are constants or variable.
		func h[E any, T ~[]E](m, n int) {
			print(make(T, 3))    //@ types(T)
			print(make(T, 3, 5)) //@ types(T)
			print(make(T, m))    //@ types(T)
			print(make(T, m, n)) //@ types(T)
		}
		func i[K comparable, E any, T ~map[K]E](m int) {
			print(make(T))    //@ types(T)
			print(make(T, 5)) //@ types(T)
			print(make(T, m)) //@ types(T)
		}
		func j[E any, T ~chan E](m int) {
			print(make(T))    //@ types(T)
			print(make(T, 6)) //@ types(T)
			print(make(T, m)) //@ types(T)
		}
		func From() {
			type H []int32
			h[int32, H](3, 4)
			type I map[int8]H
			i[int8, H, I](5)
			type J chan I
			j[I, J](6)
		}
		`,
		`
		package p11

		func h[T ~[4]int](x T) {
			print(len(x), cap(x)) //@ types(int, int)
		}
		func i[T ~[4]byte | []int | ~chan uint8](x T) {
			print(len(x), cap(x)) //@ types(int, int)
		}
		func j[T ~[4]int | any | map[string]int]() {
			print(new(T)) //@ types("*T")
		}
		func k[T ~[4]int | any | map[string]int](x T) {
			print(x) //@ types(T)
			panic(x)
		}
		`,
		`
		package p12

		func f[E any, F ~func() E](x F) {
			print(x, x()) //@ types(F, E)
		}
		func From() {
			type T func() int
			f[int, T](func() int { return 0 })
			f[int, func() int](func() int { return 1 })
		}
		`,
		`
		package p13

		func f[E any, M ~map[string]E](m M) {
			y, ok := m["lorem"]
			print(m, y, ok) //@ types(M, E, bool)
		}
		func From() {
			type O map[string][]int
			f(O{"lorem": []int{0, 1, 2, 3}})
		}
		`,
		`
		package p14

		func a[T interface{ []int64 | [5]int64 }](x T) int64 {
			print(x, x[2], x[3]) //@ types(T, int64, int64)
			x[2] = 5
			return x[3]
		}
		func b[T interface{ []byte | string }](x T) byte {
			print(x, x[3]) //@ types(T, byte)
			return x[3]
		}
		func c[T interface{ []byte }](x T) byte {
			print(x, x[2], x[3]) //@ types(T, byte, byte)
			x[2] = 'b'
			return x[3]
		}
		func d[T interface{ map[int]int64 }](x T) int64 {
			print(x, x[2], x[3]) //@ types(T, int64, int64)
			x[2] = 43
			return x[3]
		}
		func e[T ~string](t T) {
			print(t, t[0]) //@ types(T, uint8)
		}
		func f[T ~string|[]byte](t T) {
			print(t, t[0]) //@ types(T, uint8)
		}
		func g[T []byte](t T) {
			print(t, t[0]) //@ types(T, byte)
		}
		func h[T ~[4]int|[]int](t T) {
			print(t, t[0]) //@ types(T, int)
		}
		func i[T ~[4]int|*[4]int|[]int](t T) {
			print(t, t[0]) //@ types(T, int)
		}
		func j[T ~[4]int|*[4]int|[]int](t T) {
			print(t, &t[0]) //@ types(T, "*int")
		}
		`,
		`
		package p15

		type MyInt int
		type Other int
		type MyInterface interface{ foo() }

		// ChangeType tests
		func ct0(x int) { v := MyInt(x);  print(x, v) /*@ types(int, "p15.MyInt")*/ }
		func ct1[T MyInt | Other, S int ](x S) { v := T(x);  print(x, v) /*@ types(S, T)*/ }
		func ct2[T int, S MyInt | int ](x S) { v := T(x); print(x, v) /*@ types(S, T)*/ }
		func ct3[T MyInt | Other, S MyInt | int ](x S) { v := T(x) ; print(x, v) /*@ types(S, T)*/ }

		// Convert tests
		func co0[T int | int8](x MyInt) { v := T(x); print(x, v) /*@ types("p15.MyInt", T)*/}
		func co1[T int | int8](x T) { v := MyInt(x); print(x, v) /*@ types(T, "p15.MyInt")*/ }
		func co2[S, T int | int8](x T) { v := S(x); print(x, v) /*@ types(T, S)*/ }

		// MakeInterface tests
		func mi0[T MyInterface](x T) { v := MyInterface(x); print(x, v) /*@ types(T, "p15.MyInterface")*/ }

		// NewConst tests
		func nc0[T any]() { v := (*T)(nil); print(v) /*@ types("*T")*/}

		// SliceToArrayPointer
		func sl0[T *[4]int | *[2]int](x []int) { v := T(x); print(x, v) /*@ types("[]int", T)*/ }
		func sl1[T *[4]int | *[2]int, S []int](x S) { v := T(x); print(x, v) /*@ types(S, T)*/ }
		`,
		`
		package p16

		func c[T interface{ foo() string }](x T) {
			print(x, x.foo, x.foo())  /*@ types(T, "func() string", string)*/
		}
		`,
		`
		package p17

		func eq[T comparable](t T, i interface{}) bool {
			return t == i
		}
		`,
		// TODO(59983): investigate why writing g.c panics in (*FieldAddr).String.
		`
		package p18

		type S struct{ f int }
		func c[P *S]() []P { return []P{{f: 1}} }
		`,
		`
		package p19

		func sign[bytes []byte | string](s bytes) (bool, bool) {
			neg := false
			if len(s) > 0 && (s[0] == '-' || s[0] == '+') {
				neg = s[0] == '-'
				s = s[1:]
			}
			return !neg, len(s) > 0
		}
		`,
		`package p20

		func digits[bytes []byte | string](s bytes) bool {
			for _, c := range []byte(s) {
				if c < '0' || '9' < c {
					return false
				}
			}
			return true
		}
		`,
		`
		package p21

		type E interface{}

		func Foo[T E, PT interface{ *T }]() T {
			pt := PT(new(T))
			x := *pt
			print(x)  /*@ types(T)*/
			return x
		}
		`,
		`
		package p22

		func f[M any, PM *M](p PM) {
			var m M
			*p = m
			print(m)  /*@ types(M)*/
			print(p)  /*@ types(PM)*/
		}
		`,
		`
		package p23

		type A struct{int}
		func (*A) Marker() {}

		type B struct{string}
		func (*B) Marker() {}

		type C struct{float32}
		func (*C) Marker() {}

		func process[T interface {
			*A
			*B
			*C
			Marker()
		}](v T) {
			v.Marker()
			a := *(any(v).(*A)); print(a)  /*@ types("p23.A")*/
			b := *(any(v).(*B)); print(b)  /*@ types("p23.B")*/
			c := *(any(v).(*C)); print(c)  /*@ types("p23.C")*/
		}
		`,
		`
		package p24

		func a[T any](f func() [4]T) {
			x := len(f())
			print(x) /*@ types("int")*/
		}

		func b[T [4]any](f func() T) {
			x := len(f())
			print(x) /*@ types("int")*/
		}

		func c[T any](f func() *[4]T) {
			x := len(f())
			print(x) /*@ types("int")*/
		}

		func d[T *[4]any](f func() T) {
			x := len(f())
			print(x) /*@ types("int")*/
		}
		`,
		`
		package p25

		func a[T any]() {
			var f func() [4]T
			for i, v := range f() {
				print(i, v) /*@ types("int", "T")*/
			}
		}

		func b[T [4]any](f func() T) {
			for i, v := range f() {
				print(i, v) /*@ types("int", "any")*/
			}
		}

		func c[T any](f func() *[4]T) {
			for i, v := range f() {
				print(i, v) /*@ types("int", "T")*/
			}
		}

		func d[T *[4]any](f func() T) {
			for i, v := range f() {
				print(i, v) /*@ types("int", "any")*/
			}
		}
		`,
		`
		package issue64324

		type bar[T any] interface {
			Bar(int) T
		}
		type foo[T any] interface {
			bar[[]T]
			*T
		}
		func Foo[T any, F foo[T]](d int) {
			m := new(T)
			f := F(m)
			print(f.Bar(d)) /*@ types("[]T")*/
		}
		`, `
		package issue64324b

		type bar[T any] interface {
			Bar(int) T
		}
		type baz[T any] interface {
			bar[*int]
			*int
		}

		func Baz[I baz[string]](d int) {
			m := new(int)
			f := I(m)
			print(f.Bar(d)) /*@ types("*int")*/
		}
		`,
	} {
		pkgname := parsePackageClause(t, content)
		t.Run(pkgname, func(t *testing.T) {
			t.Parallel()
			ssapkg, ppkg := buildPackage(t, content, ssa.SanityCheckFunctions)
			fset := ssapkg.Prog.Fset
			file := ppkg.Syntax[0]

			// Collect all notes in f, i.e. comments starting with "//@ types".
			notes, err := expect.ExtractGo(fset.File(file.Pos()), file)
			if err != nil {
				t.Errorf("expect.ExtractGo: %v", err)
			}

			// Collect calls to the builtin print function.
			fns := make(map[*ssa.Function]bool)
			for _, mem := range ssapkg.Members {
				if fn, ok := mem.(*ssa.Function); ok {
					fns[fn] = true
				}
			}
			probes := callsTo(fns, "print")
			expectations := matchNotes(fset, notes, probes)

			for call := range probes {
				if expectations[call] == nil {
					t.Errorf("Unmatched call: %v", call)
				}
			}

			// Check each expectation.
			for call, note := range expectations {
				var args []string
				for _, a := range call.Args {
					args = append(args, a.Type().String())
				}
				if got, want := fmt.Sprint(args), fmt.Sprint(note.Args); got != want {
					t.Errorf("Arguments to print() were expected to be %q. got %q", want, got)
					logFunction(t, probes[call])
				}
			}
		})
	}
}

// callsTo finds all calls to an SSA value named fname,
// and returns a map from each call site to its enclosing function.
func callsTo(fns map[*ssa.Function]bool, fname string) map[*ssa.CallCommon]*ssa.Function {
	callsites := make(map[*ssa.CallCommon]*ssa.Function)
	for fn := range fns {
		for _, bb := range fn.Blocks {
			for _, i := range bb.Instrs {
				if i, ok := i.(ssa.CallInstruction); ok {
					call := i.Common()
					if call.Value.Name() == fname {
						callsites[call] = fn
					}
				}
			}
		}
	}
	return callsites
}

// matchNotes returns a mapping from call sites (found by callsTo)
// to the first "//@ note" comment on the same line.
func matchNotes(fset *token.FileSet, notes []*expect.Note, calls map[*ssa.CallCommon]*ssa.Function) map[*ssa.CallCommon]*expect.Note {
	// Matches each probe with a note that has the same line.
	sameLine := func(x, y token.Pos) bool {
		xp := fset.Position(x)
		yp := fset.Position(y)
		return xp.Filename == yp.Filename && xp.Line == yp.Line
	}
	expectations := make(map[*ssa.CallCommon]*expect.Note)
	for call := range calls {
		for _, note := range notes {
			if sameLine(call.Pos(), note.Pos) {
				expectations[call] = note
				break // first match is good enough.
			}
		}
	}
	return expectations
}

// TestInstructionString tests serializing instructions via Instruction.String().
func TestInstructionString(t *testing.T) {
	// Tests (ssa.Instruction).String(). Instructions are from a single go file.
	// The Instructions tested are those that match a comment of the form:
	//
	//	//@ instrs(f, kind, strs...)
	//
	// where f is the name of the function, kind is the type of the instructions matched
	// within the function, and tests that the String() value for all of the instructions
	// matched of String() is strs (in some order).
	// See x/tools/go/expect for details on the syntax.

	const contents = `
	package p

	//@ instrs("f0", "*ssa.TypeAssert")
	//@ instrs("f0", "*ssa.Call", "print(nil:interface{}, 0:int)")
	func f0(x int) { // non-generic smoke test.
		var i interface{}
		print(i, 0)
	}

	//@ instrs("f1", "*ssa.Alloc", "local T (u)")
	//@ instrs("f1", "*ssa.FieldAddr", "&t0.x [#0]")
	func f1[T ~struct{ x string }]() T {
		u := T{"lorem"}
		return u
	}

	//@ instrs("f1b", "*ssa.Alloc", "new T (complit)")
	//@ instrs("f1b", "*ssa.FieldAddr", "&t0.x [#0]")
	func f1b[T ~struct{ x string }]() *T {
		u := &T{"lorem"}
		return u
	}

	//@ instrs("f2", "*ssa.TypeAssert", "typeassert t0.(interface{})")
	//@ instrs("f2", "*ssa.Call", "invoke x.foo()")
	func f2[T interface{ foo() string }](x T) {
		_ = x.foo
		_ = x.foo()
	}

	//@ instrs("f3", "*ssa.TypeAssert", "typeassert t0.(interface{})")
	//@ instrs("f3", "*ssa.Call", "invoke x.foo()")
	func f3[T interface{ foo() string; comparable }](x T) {
		_ = x.foo
		_ = x.foo()
	}

	//@ instrs("f4", "*ssa.BinOp", "t1 + 1:int", "t2 < 4:int")
	//@ instrs("f4", "*ssa.Call", "f()", "print(t2, t4)")
	func f4[T [4]string](f func() T) {
		for i, v := range f() {
			print(i, v)
		}
	}

	//@ instrs("f5", "*ssa.Call", "nil:func()()")
	func f5() {
		var f func()
		f()
	}

	type S struct{ f int }

	//@ instrs("f6", "*ssa.Alloc", "new [1]P (slicelit)", "new S (complit)")
	//@ instrs("f6", "*ssa.IndexAddr", "&t0[0:int]")
	//@ instrs("f6", "*ssa.FieldAddr", "&t2.f [#0]")
	func f6[P *S]() []P { return []P{{f: 1}} }

	//@ instrs("f7", "*ssa.Alloc", "local S (complit)")
	//@ instrs("f7", "*ssa.FieldAddr", "&t0.f [#0]")
	func f7[T any, S struct{f T}](x T) S { return S{f: x} }

	//@ instrs("f8", "*ssa.Alloc", "new [1]P (slicelit)", "new struct{f T} (complit)")
	//@ instrs("f8", "*ssa.IndexAddr", "&t0[0:int]")
	//@ instrs("f8", "*ssa.FieldAddr", "&t2.f [#0]")
	func f8[T any, P *struct{f T}](x T) []P { return []P{{f: x}} }

	//@ instrs("f9", "*ssa.Alloc", "new [1]PS (slicelit)", "new S (complit)")
	//@ instrs("f9", "*ssa.IndexAddr", "&t0[0:int]")
	//@ instrs("f9", "*ssa.FieldAddr", "&t2.f [#0]")
	func f9[T any, S struct{f T}, PS *S](x T) {
		_ = []PS{{f: x}}
	}

	//@ instrs("f10", "*ssa.FieldAddr", "&t0.x [#0]")
	//@ instrs("f10", "*ssa.Store", "*t0 = *new(T):T", "*t1 = 4:int")
	func f10[T ~struct{ x, y int }]() T {
		var u T
		u = T{x: 4}
		return u
	}

	//@ instrs("f11", "*ssa.FieldAddr", "&t1.y [#1]")
	//@ instrs("f11", "*ssa.Store", "*t1 = *new(T):T", "*t2 = 5:int")
	func f11[T ~struct{ x, y int }, PT *T]() PT {
		var u PT = new(T)
		*u = T{y: 5}
		return u
	}

	//@ instrs("f12", "*ssa.Alloc", "new struct{f T} (complit)")
	//@ instrs("f12", "*ssa.MakeMap", "make map[P]bool 1:int")
	func f12[T any, P *struct{f T}](x T) map[P]bool { return map[P]bool{{}: true} }

	//@ instrs("f13", "*ssa.IndexAddr", "&v[0:int]")
	//@ instrs("f13", "*ssa.Store", "*t0 = 7:int", "*v = *new(A):A")
	func f13[A [3]int, PA *A](v PA) {
		*v = A{7}
	}

	//@ instrs("f14", "*ssa.Call", "invoke t1.Set(0:int)")
	func f14[T any, PT interface {
		Set(int)
		*T
	}]() {
		var t T
		p := PT(&t)
		p.Set(0)
	}

	//@ instrs("f15", "*ssa.MakeClosure", "make closure (interface{Set(int); *T}).Set$bound [t1]")
	func f15[T any, PT interface {
		Set(int)
		*T
	}]() func(int) {
		var t T
		p := PT(&t)
		return p.Set
	}
	`

	// Parse
	conf := loader.Config{ParserMode: parser.ParseComments}
	const fname = "p.go"
	f, err := conf.ParseFile(fname, contents)
	if err != nil {
		t.Fatalf("parse: %v", err)
	}
	conf.CreateFromFiles("p", f)

	// Load
	lprog, err := conf.Load()
	if err != nil {
		t.Fatalf("Load: %v", err)
	}

	// Create and build SSA
	prog := ssa.NewProgram(lprog.Fset, ssa.SanityCheckFunctions)
	for _, info := range lprog.AllPackages {
		if info.TransitivelyErrorFree {
			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
		}
	}
	p := prog.Package(lprog.Package("p").Pkg)
	p.Build()

	// Collect all notes in f, i.e. comments starting with "//@ instr".
	notes, err := expect.ExtractGo(prog.Fset.File(f.Pos()), f)
	if err != nil {
		t.Errorf("expect.ExtractGo: %v", err)
	}

	// Expectation is a {function, type string} -> {want, matches}
	// where matches is all Instructions.String() that match the key.
	// Each expectation is that some permutation of matches is wants.
	type expKey struct {
		function string
		kind     string
	}
	type expValue struct {
		wants   []string
		matches []string
	}
	expectations := make(map[expKey]*expValue)
	for _, note := range notes {
		if note.Name == "instrs" {
			if len(note.Args) < 2 {
				t.Error("Had @instrs annotation without at least 2 arguments")
				continue
			}
			fn, kind := fmt.Sprint(note.Args[0]), fmt.Sprint(note.Args[1])
			var wants []string
			for _, arg := range note.Args[2:] {
				wants = append(wants, fmt.Sprint(arg))
			}
			expectations[expKey{fn, kind}] = &expValue{wants, nil}
		}
	}

	// Collect all Instructions that match the expectations.
	for _, mem := range p.Members {
		if fn, ok := mem.(*ssa.Function); ok {
			for _, bb := range fn.Blocks {
				for _, i := range bb.Instrs {
					kind := fmt.Sprintf("%T", i)
					if e := expectations[expKey{fn.Name(), kind}]; e != nil {
						e.matches = append(e.matches, i.String())
					}
				}
			}
		}
	}

	// Check each expectation.
	for key, value := range expectations {
		fn, ok := p.Members[key.function].(*ssa.Function)
		if !ok {
			t.Errorf("Expectation on %s does not match a member in %s", key.function, p.Pkg.Name())
		}
		got, want := value.matches, value.wants
		sort.Strings(got)
		sort.Strings(want)
		if !reflect.DeepEqual(want, got) {
			t.Errorf("Within %s wanted instructions of kind %s: %q. got %q", key.function, key.kind, want, got)
			logFunction(t, fn)
		}
	}
}

func logFunction(t testing.TB, fn *ssa.Function) {
	// TODO: Consider adding a ssa.Function.GoString() so this can be logged to t via '%#v'.
	var buf bytes.Buffer
	ssa.WriteFunction(&buf, fn)
	t.Log(buf.String())
}


================================================
FILE: go/ssa/builder_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strings"
	"testing"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/testenv"
)

func isEmpty(f *ssa.Function) bool { return f.Blocks == nil }

// Tests that programs partially loaded from gc object files contain
// functions with no code for the external portions, but are otherwise ok.
func TestBuildPackage(t *testing.T) {
	testenv.NeedsGoBuild(t) // for importer.Default()

	input := `
package main

import (
	"bytes"
	"io"
	"testing"
)

func main() {
        var t testing.T
	    t.Parallel()    // static call to external declared method
        t.Fail()        // static call to promoted external declared method
        testing.Short() // static call to external package-level function

        var w io.Writer = new(bytes.Buffer)
        w.Write(nil)    // interface invoke of external declared method
}
`

	// Parse the file.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "input.go", input, 0)
	if err != nil {
		t.Fatal(err)
		return
	}

	// Build an SSA program from the parsed file.
	// Load its dependencies from gc binary export data.
	mode := ssa.SanityCheckFunctions
	mainPkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
		types.NewPackage("main", ""), []*ast.File{f}, mode)
	if err != nil {
		t.Fatal(err)
		return
	}

	// The main package, its direct and indirect dependencies are loaded.
	deps := []string{
		// directly imported dependencies:
		"bytes", "io", "testing",
		// indirect dependencies mentioned by
		// the direct imports' export data
		"sync", "unicode", "time",
	}

	prog := mainPkg.Prog
	all := prog.AllPackages()
	if len(all) <= len(deps) {
		t.Errorf("unexpected set of loaded packages: %q", all)
	}
	for _, path := range deps {
		pkg := prog.ImportedPackage(path)
		if pkg == nil {
			t.Errorf("package not loaded: %q", path)
			continue
		}

		// External packages should have no function bodies (except for wrappers).
		isExt := pkg != mainPkg

		// init()
		if isExt && !isEmpty(pkg.Func("init")) {
			t.Errorf("external package %s has non-empty init", pkg)
		} else if !isExt && isEmpty(pkg.Func("init")) {
			t.Errorf("main package %s has empty init", pkg)
		}

		for _, mem := range pkg.Members {
			switch mem := mem.(type) {
			case *ssa.Function:
				// Functions at package level.
				if isExt && !isEmpty(mem) {
					t.Errorf("external function %s is non-empty", mem)
				} else if !isExt && isEmpty(mem) {
					t.Errorf("function %s is empty", mem)
				}

			case *ssa.Type:
				// Methods of named types T.
				// (In this test, all exported methods belong to *T not T.)
				if !isExt {
					t.Fatalf("unexpected name type in main package: %s", mem)
				}
				mset := prog.MethodSets.MethodSet(types.NewPointer(mem.Type()))
				for i, n := 0, mset.Len(); i < n; i++ {
					m := prog.MethodValue(mset.At(i))
					// For external types, only synthetic wrappers have code.
					expExt := !strings.Contains(m.Synthetic, "wrapper")
					if expExt && !isEmpty(m) {
						t.Errorf("external method %s is non-empty: %s",
							m, m.Synthetic)
					} else if !expExt && isEmpty(m) {
						t.Errorf("method function %s is empty: %s",
							m, m.Synthetic)
					}
				}
			}
		}
	}

	expectedCallee := []string{
		"(*testing.T).Parallel",
		"(*testing.common).Fail",
		"testing.Short",
		"N/A",
	}
	callNum := 0
	for _, b := range mainPkg.Func("main").Blocks {
		for _, instr := range b.Instrs {
			switch instr := instr.(type) {
			case ssa.CallInstruction:
				call := instr.Common()
				if want := expectedCallee[callNum]; want != "N/A" {
					got := call.StaticCallee().String()
					if want != got {
						t.Errorf("call #%d from main.main: got callee %s, want %s",
							callNum, got, want)
					}
				}
				callNum++
			}
		}
	}
	if callNum != 4 {
		t.Errorf("in main.main: got %d calls, want %d", callNum, 4)
	}
}

// Tests that methods from indirect dependencies not subject to
// CreatePackage are created as needed.
func TestNoIndirectCreatePackage(t *testing.T) {
	testenv.NeedsGoBuild(t) // for go/packages

	fs := openTxtar(t, filepath.Join(analysistest.TestData(), "indirect.txtar"))
	pkgs := loadPackages(t, fs, "testdata/a")
	a := pkgs[0]

	// Create a from syntax, its direct deps b from types, but not indirect deps c.
	prog := ssa.NewProgram(a.Fset, ssa.SanityCheckFunctions|ssa.PrintFunctions)
	aSSA := prog.CreatePackage(a.Types, a.Syntax, a.TypesInfo, false)
	for _, p := range a.Types.Imports() {
		prog.CreatePackage(p, nil, nil, true)
	}

	// Build SSA for package a.
	aSSA.Build()

	// Find the function in the sole call in the sole block of function a.A.
	var got string
	for _, instr := range aSSA.Members["A"].(*ssa.Function).Blocks[0].Instrs {
		if call, ok := instr.(*ssa.Call); ok {
			f := call.Call.Value.(*ssa.Function)
			got = fmt.Sprintf("%v # %s", f, f.Synthetic)
			break
		}
	}
	want := "(testdata/c.C).F # from type information (on demand)"
	if got != want {
		t.Errorf("for sole call in a.A, got: <<%s>>, want <<%s>>", got, want)
	}
}

// TestRuntimeTypes tests that (*Program).RuntimeTypes() includes all necessary types.
func TestRuntimeTypes(t *testing.T) {
	testenv.NeedsGoBuild(t) // for importer.Default()

	// TODO(adonovan): these test cases don't really make logical
	// sense any more. Rethink.

	tests := []struct {
		input string
		want  []string
	}{
		// A package-level type is needed.
		{`package A; type T struct{}; func (T) f() {}; var x any = T{}`,
			[]string{"*p.T", "p.T"},
		},
		// An unexported package-level type is not needed.
		{`package B; type t struct{}; func (t) f() {}`,
			nil,
		},
		// Subcomponents of type of exported package-level var are needed.
		{`package C; import "bytes"; var V struct {*bytes.Buffer}; var x any = &V`,
			[]string{"*bytes.Buffer", "*struct{*bytes.Buffer}", "struct{*bytes.Buffer}"},
		},
		// Subcomponents of type of unexported package-level var are not needed.
		{`package D; import "bytes"; var v struct {*bytes.Buffer}; var x any = v`,
			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
		},
		// Subcomponents of type of exported package-level function are needed.
		{`package E; import "bytes"; func F(struct {*bytes.Buffer}) {}; var v any = F`,
			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
		},
		// Subcomponents of type of unexported package-level function are not needed.
		{`package F; import "bytes"; func f(struct {*bytes.Buffer}) {}; var v any = f`,
			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
		},
		// Subcomponents of type of exported method of uninstantiated unexported type are not needed.
		{`package G; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v x`,
			nil,
		},
		// ...unless used by MakeInterface.
		{`package G2; import "bytes"; type x struct{}; func (x) G(struct {*bytes.Buffer}) {}; var v interface{} = x{}`,
			[]string{"*bytes.Buffer", "*p.x", "p.x", "struct{*bytes.Buffer}"},
		},
		// Subcomponents of type of unexported method are not needed.
		{`package I; import "bytes"; type X struct{}; func (X) G(struct {*bytes.Buffer}) {}; var x any = X{}`,
			[]string{"*bytes.Buffer", "*p.X", "p.X", "struct{*bytes.Buffer}"},
		},
		// Local types aren't needed.
		{`package J; import "bytes"; func f() { type T struct {*bytes.Buffer}; var t T; _ = t }`,
			nil,
		},
		// ...unless used by MakeInterface.
		{`package K; import "bytes"; func f() { type T struct {*bytes.Buffer}; _ = interface{}(T{}) }`,
			[]string{"*bytes.Buffer", "*p.T", "p.T"},
		},
		// Types used as operand of MakeInterface are needed.
		{`package L; import "bytes"; func f() { _ = interface{}(struct{*bytes.Buffer}{}) }`,
			[]string{"*bytes.Buffer", "struct{*bytes.Buffer}"},
		},
		// MakeInterface is optimized away when storing to a blank.
		{`package M; import "bytes"; var _ interface{} = struct{*bytes.Buffer}{}`,
			nil,
		},
		// MakeInterface does not create runtime type for parameterized types.
		{`package N; var g interface{}; func f[S any]() { var v []S; g = v }; `,
			nil,
		},
	}
	for _, test := range tests {
		// Parse the file.
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "input.go", test.input, 0)
		if err != nil {
			t.Errorf("test %q: %s", test.input[:15], err)
			continue
		}

		// Create a single-file main package.
		// Load dependencies from gc binary export data.
		mode := ssa.SanityCheckFunctions
		ssapkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset,
			types.NewPackage("p", ""), []*ast.File{f}, mode)
		if err != nil {
			t.Errorf("test %q: %s", test.input[:15], err)
			continue
		}

		var typstrs []string
		for _, T := range ssapkg.Prog.RuntimeTypes() {
			if types.IsInterface(T) || types.NewMethodSet(T).Len() == 0 {
				continue // skip interfaces and types without methods
			}
			typstrs = append(typstrs, T.String())
		}
		sort.Strings(typstrs)

		if !reflect.DeepEqual(typstrs, test.want) {
			t.Errorf("test 'package %s': got %q, want %q",
				f.Name.Name, typstrs, test.want)
		}
	}
}

// TestInit tests that synthesized init functions are correctly formed.
// Bare init functions omit calls to dependent init functions and the use of
// an init guard. They are useful in cases where the client uses a different
// calling convention for init functions, or cases where it is easier for a
// client to analyze bare init functions. Both of these aspects are used by
// the llgo compiler for simpler integration with gccgo's runtime library,
// and to simplify the analysis whereby it deduces which stores to globals
// can be lowered to global initializers.
func TestInit(t *testing.T) {
	tests := []struct {
		mode        ssa.BuilderMode
		input, want string
	}{
		{0, `package A; import _ "errors"; var i int = 42`,
			`# Name: A.init
# Package: A
# Synthetic: package initializer
func init():
0:                                                                entry P:0 S:2
	t0 = *init$guard                                                   bool
	if t0 goto 2 else 1
1:                                                    init.start P:1 S:1 idom:0
	*init$guard = true:bool
	t1 = errors.init()                                                   ()
	*i = 42:int
	jump 2
2:                                                     init.done P:2 S:0 idom:0
	return

`},
		{ssa.BareInits, `package B; import _ "errors"; var i int = 42`,
			`# Name: B.init
# Package: B
# Synthetic: package initializer
func init():
0:                                                                entry P:0 S:0
	*i = 42:int
	return

`},
	}
	for _, test := range tests {
		// Create a single-file main package.
		mainPkg, _ := buildPackage(t, test.input, test.mode)
		name := mainPkg.Pkg.Name()
		initFunc := mainPkg.Func("init")
		if initFunc == nil {
			t.Errorf("test 'package %s': no init function", name)
			continue
		}

		var initbuf bytes.Buffer
		_, err := initFunc.WriteTo(&initbuf)
		if err != nil {
			t.Errorf("test 'package %s': WriteTo: %s", name, err)
			continue
		}

		if initbuf.String() != test.want {
			t.Errorf("test 'package %s': got %s, want %s", name, initbuf.String(), test.want)
		}
	}
}

// TestSyntheticFuncs checks that the expected synthetic functions are
// created, reachable, and not duplicated.
func TestSyntheticFuncs(t *testing.T) {
	const input = `package P
type T int
func (T) f() int
func (*T) g() int
var (
	// thunks
	a = T.f
	b = T.f
	c = (struct{T}).f
	d = (struct{T}).f
	e = (*T).g
	f = (*T).g
	g = (struct{*T}).g
	h = (struct{*T}).g

	// bounds
	i = T(0).f
	j = T(0).f
	k = new(T).g
	l = new(T).g

	// wrappers
	m interface{} = struct{T}{}
	n interface{} = struct{T}{}
	o interface{} = struct{*T}{}
	p interface{} = struct{*T}{}
	q interface{} = new(struct{T})
	r interface{} = new(struct{T})
	s interface{} = new(struct{*T})
	t interface{} = new(struct{*T})
)
`
	pkg, _ := buildPackage(t, input, ssa.BuilderMode(0))

	// Enumerate reachable synthetic functions
	want := map[string]string{
		"(*P.T).g$bound": "bound method wrapper for func (*P.T).g() int",
		"(P.T).f$bound":  "bound method wrapper for func (P.T).f() int",

		"(*P.T).g$thunk":         "thunk for func (*P.T).g() int",
		"(P.T).f$thunk":          "thunk for func (P.T).f() int",
		"(struct{*P.T}).g$thunk": "thunk for func (*P.T).g() int",
		"(struct{P.T}).f$thunk":  "thunk for func (P.T).f() int",

		"(*P.T).f":          "wrapper for func (P.T).f() int",
		"(*struct{*P.T}).f": "wrapper for func (P.T).f() int",
		"(*struct{*P.T}).g": "wrapper for func (*P.T).g() int",
		"(*struct{P.T}).f":  "wrapper for func (P.T).f() int",
		"(*struct{P.T}).g":  "wrapper for func (*P.T).g() int",
		"(struct{*P.T}).f":  "wrapper for func (P.T).f() int",
		"(struct{*P.T}).g":  "wrapper for func (*P.T).g() int",
		"(struct{P.T}).f":   "wrapper for func (P.T).f() int",

		"P.init": "package initializer",
	}
	var seen []string // may contain dups
	for fn := range ssautil.AllFunctions(pkg.Prog) {
		if fn.Synthetic == "" {
			continue
		}
		name := fn.String()
		wantDescr, ok := want[name]
		if !ok {
			t.Errorf("got unexpected/duplicate func: %q: %q", name, fn.Synthetic)
			continue
		}
		seen = append(seen, name)

		if wantDescr != fn.Synthetic {
			t.Errorf("(%s).Synthetic = %q, want %q", name, fn.Synthetic, wantDescr)
		}
	}

	for _, name := range seen {
		delete(want, name)
	}
	for fn, descr := range want {
		t.Errorf("want func: %q: %q", fn, descr)
	}
}

// TestPhiElimination ensures that dead phis, including those that
// participate in a cycle, are properly eliminated.
func TestPhiElimination(t *testing.T) {
	const input = `
package p

func f() error

func g(slice []int) {
	for {
		for range slice {
			// e should not be lifted to a dead φ-node.
			e := f()
			h(e)
		}
	}
}

func h(error)
`
	// The SSA code for this function should look something like this:
	// 0:
	//         jump 1
	// 1:
	//         t0 = len(slice)
	//         jump 2
	// 2:
	//         t1 = phi [1: -1:int, 3: t2]
	//         t2 = t1 + 1:int
	//         t3 = t2 < t0
	//         if t3 goto 3 else 1
	// 3:
	//         t4 = f()
	//         t5 = h(t4)
	//         jump 2
	//
	// But earlier versions of the SSA construction algorithm would
	// additionally generate this cycle of dead phis:
	//
	// 1:
	//         t7 = phi [0: nil:error, 2: t8] #e
	//         ...
	// 2:
	//         t8 = phi [1: t7, 3: t4] #e
	//         ...

	p, _ := buildPackage(t, input, ssa.BuilderMode(0))
	g := p.Func("g")

	phis := 0
	for _, b := range g.Blocks {
		for _, instr := range b.Instrs {
			if _, ok := instr.(*ssa.Phi); ok {
				phis++
			}
		}
	}
	if phis != 1 {
		g.WriteTo(os.Stderr)
		t.Errorf("expected a single Phi (for the range index), got %d", phis)
	}
}

// TestGenericDecls ensures that *unused* generic types, methods and functions
// signatures can be built.
//
// TODO(taking): Add calls from non-generic functions to instantiations of generic functions.
// TODO(taking): Add globals with types that are instantiations of generic functions.
func TestGenericDecls(t *testing.T) {
	const input = `
package p

import "unsafe"

type Pointer[T any] struct {
	v unsafe.Pointer
}

func (x *Pointer[T]) Load() *T {
	return (*T)(LoadPointer(&x.v))
}

func Load[T any](x *Pointer[T]) *T {
	return x.Load()
}

func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
`
	// The SSA members for this package should look something like this:
	//          func  LoadPointer func(addr *unsafe.Pointer) (val unsafe.Pointer)
	//      type  Pointer     struct{v unsafe.Pointer}
	//        method (*Pointer[T any]) Load() *T
	//      func  init        func()
	//      var   init$guard  bool

	p, _ := buildPackage(t, input, ssa.BuilderMode(0))

	if load := p.Func("Load"); load.Signature.TypeParams().Len() != 1 {
		t.Errorf("expected a single type param T for Load got %q", load.Signature)
	}
	if ptr := p.Type("Pointer"); ptr.Type().(*types.Named).TypeParams().Len() != 1 {
		t.Errorf("expected a single type param T for Pointer got %q", ptr.Type())
	}
}

func TestGenericWrappers(t *testing.T) {
	const input = `
package p

type S[T any] struct {
	t *T
}

func (x S[T]) M() T {
	return *(x.t)
}

var thunk = S[int].M

var g S[int]
var bound = g.M

type R[T any] struct{ S[T] }

var indirect = R[int].M
`
	// The relevant SSA members for this package should look something like this:
	// var   bound      func() int
	// var   thunk      func(S[int]) int
	// var   wrapper    func(R[int]) int

	for _, mode := range []ssa.BuilderMode{ssa.BuilderMode(0), ssa.InstantiateGenerics} {
		p, _ := buildPackage(t, input, mode)

		for _, entry := range []struct {
			name    string // name of the package variable
			typ     string // type of the package variable
			wrapper string // wrapper function to which the package variable is set
			callee  string // callee within the wrapper function
		}{
			{
				"bound",
				"*func() int",
				"(p.S[int]).M$bound",
				"(p.S[int]).M[int]",
			},
			{
				"thunk",
				"*func(p.S[int]) int",
				"(p.S[int]).M$thunk",
				"(p.S[int]).M[int]",
			},
			{
				"indirect",
				"*func(p.R[int]) int",
				"(p.R[int]).M$thunk",
				"(p.S[int]).M[int]",
			},
		} {
			t.Run(entry.name, func(t *testing.T) {
				v := p.Var(entry.name)
				if v == nil {
					t.Fatalf("Did not find variable for %q in %s", entry.name, p.String())
				}
				if v.Type().String() != entry.typ {
					t.Errorf("Expected type for variable %s: %q. got %q", v, entry.typ, v.Type())
				}

				// Find the wrapper for v. This is stored exactly once in init.
				var wrapper *ssa.Function
				for _, bb := range p.Func("init").Blocks {
					for _, i := range bb.Instrs {
						if store, ok := i.(*ssa.Store); ok && v == store.Addr {
							switch val := store.Val.(type) {
							case *ssa.Function:
								wrapper = val
							case *ssa.MakeClosure:
								wrapper = val.Fn.(*ssa.Function)
							}
						}
					}
				}
				if wrapper == nil {
					t.Fatalf("failed to find wrapper function for %s", entry.name)
				}
				if wrapper.String() != entry.wrapper {
					t.Errorf("Expected wrapper function %q. got %q", wrapper, entry.wrapper)
				}

				// Find the callee within the wrapper. There should be exactly one call.
				var callee *ssa.Function
				for _, bb := range wrapper.Blocks {
					for _, i := range bb.Instrs {
						if call, ok := i.(*ssa.Call); ok {
							callee = call.Call.StaticCallee()
						}
					}
				}
				if callee == nil {
					t.Fatalf("failed to find callee within wrapper %s", wrapper)
				}
				if callee.String() != entry.callee {
					t.Errorf("Expected callee in wrapper %q is %q. got %q", v, entry.callee, callee)
				}
			})
		}
	}
}

// TestTypeparamTest builds SSA over compilable examples in $GOROOT/test/typeparam/*.go.

func TestTypeparamTest(t *testing.T) {
	testenv.NeedsGOROOTDir(t, "test")

	// Tests use a fake goroot to stub out standard libraries with declarations in
	// testdata/src. Decreases runtime from ~80s to ~1s.

	if runtime.GOARCH == "wasm" {
		// Consistent flakes on wasm (#64726, #69409, #69410).
		// Needs more investigation, but more likely a wasm issue
		// Disabling for now.
		t.Skip("Consistent flakes on wasm (e.g. https://go.dev/issues/64726)")
	}

	// located GOROOT based on the relative path of errors in $GOROOT/src/errors
	stdPkgs, err := packages.Load(&packages.Config{
		Mode: packages.NeedFiles,
	}, "errors")
	if err != nil {
		t.Fatalf("Failed to load errors package from std: %s", err)
	}
	goroot := filepath.Dir(filepath.Dir(filepath.Dir(stdPkgs[0].GoFiles[0])))
	dir := filepath.Join(goroot, "test", "typeparam")
	if _, err = os.Stat(dir); errors.Is(err, os.ErrNotExist) {
		t.Skipf("test/typeparam doesn't exist under GOROOT %s", goroot)
	}

	// Collect all of the .go files in
	fsys := os.DirFS(dir)
	entries, err := fs.ReadDir(fsys, ".")
	if err != nil {
		t.Fatal(err)
	}

	// Each call to buildPackage calls package.Load, which invokes "go list",
	// and with over 300 subtests this can be very slow (minutes, or tens
	// on some platforms). So, we use an overlay to map each test file to a
	// distinct single-file package and load them all at once.
	overlay := map[string][]byte{
		"go.mod": goMod("example.com", -1),
	}
	for _, entry := range entries {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".go") {
			continue // Consider standalone go files.
		}
		src, err := fs.ReadFile(fsys, entry.Name())
		if err != nil {
			t.Fatal(err)
		}
		// Only build test files that can be compiled, or compiled and run.
		if !bytes.HasPrefix(src, []byte("// run")) && !bytes.HasPrefix(src, []byte("// compile")) {
			t.Logf("%s: not detected as a run test", entry.Name())
			continue
		}

		filename := fmt.Sprintf("%s/main.go", entry.Name())
		overlay[filename] = src
	}

	// load all packages inside the overlay so 'go list' will be triggered only once.
	pkgs := loadPackages(t, overlayFS(overlay), "./...")
	for _, p := range pkgs {
		originFilename := filepath.Base(filepath.Dir(p.GoFiles[0]))
		t.Run(originFilename, func(t *testing.T) {
			t.Parallel()
			prog, _ := ssautil.Packages([]*packages.Package{p}, ssa.SanityCheckFunctions|ssa.InstantiateGenerics)
			prog.Package(p.Types).Build()
		})
	}
}

// TestOrderOfOperations ensures order of operations are as intended.
func TestOrderOfOperations(t *testing.T) {
	// Testing for the order of operations within an expression is done
	// by collecting the sequence of direct function calls within a *Function.
	// Callees are all external functions so they cannot be safely re-ordered by ssa.
	const input = `
package p

func a() int
func b() int
func c() int

func slice(s []int) []int { return s[a():b()] }
func sliceMax(s []int) []int { return s[a():b():c()] }

`

	p, _ := buildPackage(t, input, ssa.BuilderMode(0))

	for _, item := range []struct {
		fn   string
		want string // sequence of calls within the function.
	}{
		{"sliceMax", "[a() b() c()]"},
		{"slice", "[a() b()]"},
	} {
		fn := p.Func(item.fn)
		want := item.want
		t.Run(item.fn, func(t *testing.T) {
			t.Parallel()

			var calls []string
			for _, b := range fn.Blocks {
				for _, instr := range b.Instrs {
					if call, ok := instr.(ssa.CallInstruction); ok {
						calls = append(calls, call.String())
					}
				}
			}
			if got := fmt.Sprint(calls); got != want {
				fn.WriteTo(os.Stderr)
				t.Errorf("Expected sequence of function calls in %s was %s. got %s", fn, want, got)
			}
		})
	}
}

// TestGenericFunctionSelector ensures generic functions from other packages can be selected.
func TestGenericFunctionSelector(t *testing.T) {
	fsys := overlayFS(map[string][]byte{
		"go.mod":  goMod("example.com", -1),
		"main.go": []byte(`package main; import "example.com/a"; func main() { a.F[int](); a.G[int,string](); a.H(0) }`),
		"a/a.go":  []byte(`package a; func F[T any](){}; func G[S, T any](){}; func H[T any](a T){} `),
	})

	for _, mode := range []ssa.BuilderMode{
		ssa.SanityCheckFunctions,
		ssa.SanityCheckFunctions | ssa.InstantiateGenerics,
	} {

		pkgs := loadPackages(t, fsys, "example.com") // package main
		if len(pkgs) != 1 {
			t.Fatalf("Expected 1 root package but got %d", len(pkgs))
		}
		prog, _ := ssautil.Packages(pkgs, mode)
		p := prog.Package(pkgs[0].Types)
		p.Build()

		if p.Pkg.Name() != "main" {
			t.Fatalf("Expected the second package is main but got %s", p.Pkg.Name())
		}
		p.Build()

		var callees []string // callees of the CallInstruction.String() in main().
		for _, b := range p.Func("main").Blocks {
			for _, i := range b.Instrs {
				if call, ok := i.(ssa.CallInstruction); ok {
					if callee := call.Common().StaticCallee(); call != nil {
						callees = append(callees, callee.String())
					} else {
						t.Errorf("CallInstruction without StaticCallee() %q", call)
					}
				}
			}
		}
		sort.Strings(callees) // ignore the order in the code.

		want := "[example.com/a.F[int] example.com/a.G[int string] example.com/a.H[int]]"
		if got := fmt.Sprint(callees); got != want {
			t.Errorf("Expected main() to contain calls %v. got %v", want, got)
		}
	}
}

func TestIssue58491(t *testing.T) {
	// Test that a local type reaches type param in instantiation.
	src := `
		package p

		func foo[T any](blocking func() (T, error)) error {
			type result struct {
				res T
				error // ensure the method set of result is non-empty
			}

			res := make(chan result, 1)
			go func() {
				var r result
				r.res, r.error = blocking()
				res <- r
			}()
			r := <-res
			err := r // require the rtype for result when instantiated
			return err
		}
		var Inst = foo[int]
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	files := []*ast.File{f}

	pkg := types.NewPackage("p", "")
	conf := &types.Config{}
	p, _, err := ssautil.BuildPackage(conf, fset, pkg, files, ssa.SanityCheckFunctions|ssa.InstantiateGenerics)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	// Find the local type result instantiated with int.
	var found bool
	for _, rt := range p.Prog.RuntimeTypes() {
		if n, ok := rt.(*types.Named); ok {
			if u, ok := n.Underlying().(*types.Struct); ok {
				found = true
				if got, want := n.String(), "p.result"; got != want {
					t.Errorf("Expected the name %s got: %s", want, got)
				}
				if got, want := u.String(), "struct{res int; error}"; got != want {
					t.Errorf("Expected the underlying type of %s to be %s. got %s", n, want, got)
				}
			}
		}
	}
	if !found {
		t.Error("Failed to find any Named to struct types")
	}
}

func TestIssue58491Rec(t *testing.T) {
	// Roughly the same as TestIssue58491 but with a recursive type.
	src := `
		package p

		func foo[T any]() error {
			type result struct {
				res T
				next *result
				error // ensure the method set of result is non-empty
			}

			r := &result{}
			err := r // require the rtype for result when instantiated
			return err
		}
		var Inst = foo[int]
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	files := []*ast.File{f}

	pkg := types.NewPackage("p", "")
	conf := &types.Config{}
	p, _, err := ssautil.BuildPackage(conf, fset, pkg, files, ssa.SanityCheckFunctions|ssa.InstantiateGenerics)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}

	// Find the local type result instantiated with int.
	var found bool
	for _, rt := range p.Prog.RuntimeTypes() {
		if n, ok := types.Unalias(rt).(*types.Named); ok {
			if u, ok := n.Underlying().(*types.Struct); ok {
				found = true
				if got, want := n.String(), "p.result"; got != want {
					t.Errorf("Expected the name %s got: %s", want, got)
				}
				if got, want := u.String(), "struct{res int; next *p.result; error}"; got != want {
					t.Errorf("Expected the underlying type of %s to be %s. got %s", n, want, got)
				}
			}
		}
	}
	if !found {
		t.Error("Failed to find any Named to struct types")
	}
}

// TestSyntax ensures that a function's Syntax is available.
func TestSyntax(t *testing.T) {
	const input = `package p

	type P int
	func (x *P) g() *P { return x }

	func F[T ~int]() *T {
		type S1 *T
		type S2 *T
		type S3 *T
		f1 := func() S1 {
			f2 := func() S2 {
				return S2(nil)
			}
			return S1(f2())
		}
		f3 := func() S3 {
			return S3(f1())
		}
		return (*T)(f3())
	}
	var g = F[int]
	var _ = F[P] // unreferenced => not instantiated
	`

	p, _ := buildPackage(t, input, ssa.InstantiateGenerics)
	prog := p.Prog

	// Collect syntax information for all of the functions.
	got := make(map[string]string)
	for fn := range ssautil.AllFunctions(prog) {
		if fn.Name() == "init" {
			continue
		}
		syntax := fn.Syntax()
		if got[fn.Name()] != "" {
			t.Error("dup")
		}
		got[fn.Name()] = fmt.Sprintf("%T : %s @ %d", syntax, fn.Signature, prog.Fset.Position(syntax.Pos()).Line)
	}

	want := map[string]string{
		"g":          "*ast.FuncDecl : func() *p.P @ 4",
		"F":          "*ast.FuncDecl : func[T ~int]() *T @ 6",
		"F$1":        "*ast.FuncLit : func() p.S1 @ 10",
		"F$1$1":      "*ast.FuncLit : func() p.S2 @ 11",
		"F$2":        "*ast.FuncLit : func() p.S3 @ 16",
		"F[int]":     "*ast.FuncDecl : func() *int @ 6",
		"F[int]$1":   "*ast.FuncLit : func() p.S1 @ 10",
		"F[int]$1$1": "*ast.FuncLit : func() p.S2 @ 11",
		"F[int]$2":   "*ast.FuncLit : func() p.S3 @ 16",
		// ...but no F[P] etc as they are unreferenced.
		// (NB: GlobalDebug mode would cause them to be referenced.)
	}
	if !reflect.DeepEqual(got, want) {
		t.Errorf("Expected the functions with signature to be:\n\t%#v.\n Got:\n\t%#v", want, got)
	}
}

func TestGo117Builtins(t *testing.T) {
	tests := []struct {
		name     string
		src      string
		importer types.Importer
	}{
		{"slice to array pointer", "package p; var s []byte; var _ = (*[4]byte)(s)", nil},
		{"unsafe slice", `package p; import "unsafe"; var _ = unsafe.Add(nil, 0)`, importer.Default()},
		{"unsafe add", `package p; import "unsafe"; var _ = unsafe.Slice((*int)(nil), 0)`, importer.Default()},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			fset := token.NewFileSet()
			f, err := parser.ParseFile(fset, "p.go", tc.src, parser.ParseComments)
			if err != nil {
				t.Error(err)
			}
			files := []*ast.File{f}

			pkg := types.NewPackage("p", "")
			conf := &types.Config{Importer: tc.importer}
			if _, _, err := ssautil.BuildPackage(conf, fset, pkg, files, ssa.SanityCheckFunctions); err != nil {
				t.Error(err)
			}
		})
	}
}

// TestLabels just tests that anonymous labels are handled.
func TestLabels(t *testing.T) {
	tests := []string{
		`package main
		  func main() { _:println(1) }`,
		`package main
		  func main() { _:println(1); _:println(2)}`,
	}
	for _, test := range tests {
		buildPackage(t, test, ssa.BuilderMode(0))
	}
}

func TestFixedBugs(t *testing.T) {
	for _, name := range []string{
		"issue66783a",
		"issue66783b",
		"issue73594",
	} {
		t.Run(name, func(t *testing.T) {
			base := name + ".go"
			path := filepath.Join(analysistest.TestData(), "fixedbugs", base)
			fset := token.NewFileSet()
			f, err := parser.ParseFile(fset, path, nil, parser.ParseComments)
			if err != nil {
				t.Fatal(err)
			}
			files := []*ast.File{f}
			pkg := types.NewPackage(name, name)
			mode := ssa.SanityCheckFunctions | ssa.InstantiateGenerics
			// mode |= ssa.PrintFunctions // debug mode
			if _, _, err := ssautil.BuildPackage(&types.Config{}, fset, pkg, files, mode); err != nil {
				t.Error(err)
			}
		})
	}
}

func TestIssue67079(t *testing.T) {
	// This test reproduced a race in the SSA builder nearly 100% of the time.

	// Load the package.
	const src = `package p; type T int; func (T) f() {}; var _ = (*T).f`
	spkg, ppkg := buildPackage(t, src, ssa.BuilderMode(0))
	prog := spkg.Prog
	var g errgroup.Group

	// Access bodies of all functions.
	g.Go(func() error {
		for fn := range ssautil.AllFunctions(prog) {
			for _, b := range fn.Blocks {
				for _, instr := range b.Instrs {
					if call, ok := instr.(*ssa.Call); ok {
						call.Common().StaticCallee() // access call.Value
					}
				}
			}
		}
		return nil
	})

	// Force building of wrappers.
	g.Go(func() error {
		ptrT := types.NewPointer(ppkg.Types.Scope().Lookup("T").Type())
		ptrTf := types.NewMethodSet(ptrT).At(0) // (*T).f symbol
		prog.MethodValue(ptrTf)
		return nil
	})

	g.Wait() // ignore error
}

func TestGenericAliases(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)

	if os.Getenv("GENERICALIASTEST_CHILD") == "1" {
		testGenericAliases(t)
		return
	}

	testenv.NeedsExec(t)
	testenv.NeedsTool(t, "go")

	cmd := exec.Command(os.Args[0], "-test.run=TestGenericAliases")
	cmd.Env = append(os.Environ(), "GENERICALIASTEST_CHILD=1")
	if testenv.Go1Point() == 23 {
		cmd.Env = append(cmd.Env, "GOEXPERIMENT=aliastypeparams")
	}
	out, err := cmd.CombinedOutput()
	if len(out) > 0 {
		t.Logf("out=<<%s>>", out)
	}
	var exitcode int
	if err, ok := err.(*exec.ExitError); ok {
		exitcode = err.ExitCode()
	}
	const want = 0
	if exitcode != want {
		t.Errorf("exited %d, want %d", exitcode, want)
	}
}

func testGenericAliases(t *testing.T) {
	testenv.NeedsGoExperiment(t, "aliastypeparams")

	const source = `
package p

type A = uint8
type B[T any] = [4]T

var F = f[string]

func f[S any]() {
	// Two copies of f are made: p.f[S] and p.f[string]

	var v A // application of A that is declared outside of f without no type arguments
	print("p.f", "String", "p.A", v)
	print("p.f", "==", v, uint8(0))
	print("p.f[string]", "String", "p.A", v)
	print("p.f[string]", "==", v, uint8(0))


	var u B[S] // application of B that is declared outside declared outside of f with type arguments
	print("p.f", "String", "p.B[S]", u)
	print("p.f", "==", u, [4]S{})
	print("p.f[string]", "String", "p.B[string]", u)
	print("p.f[string]", "==", u, [4]string{})

	type C[T any] = struct{ s S; ap *B[T]} // declaration within f with type params
	var w C[int] // application of C with type arguments
	print("p.f", "String", "p.C[int]", w)
	print("p.f", "==", w, struct{ s S; ap *[4]int}{})
	print("p.f[string]", "String", "p.C[int]", w)
	print("p.f[string]", "==", w, struct{ s string; ap *[4]int}{})
}
`

	p, _ := buildPackage(t, source, ssa.InstantiateGenerics)

	probes := callsTo(ssautil.AllFunctions(p.Prog), "print")
	if got, want := len(probes), 3*4*2; got != want {
		t.Errorf("Found %v probes, expected %v", got, want)
	}

	const debug = false // enable to debug skips
	skipped := 0
	for probe, fn := range probes {
		// Each probe is of the form:
		// 		print("within", "test", head, tail)
		// The probe only matches within a function whose fn.String() is within.
		// This allows for different instantiations of fn to match different probes.
		// On a match, it applies the test named "test" to head::tail.
		if len(probe.Args) < 3 {
			t.Fatalf("probe %v did not have enough arguments", probe)
		}
		within, test, head, tail := constString(probe.Args[0]), probe.Args[1], probe.Args[2], probe.Args[3:]
		if within != fn.String() {
			skipped++
			if debug {
				t.Logf("Skipping %q within %q", within, fn.String())
			}
			continue // does not match function
		}

		switch test := constString(test); test {
		case "==": // All of the values are types.Identical.
			for _, v := range tail {
				if !types.Identical(head.Type(), v.Type()) {
					t.Errorf("Expected %v and %v to have identical types", head, v)
				}
			}
		case "String": // head is a string constant that all values in tail must match Type().String()
			want := constString(head)
			for _, v := range tail {
				if got := v.Type().String(); got != want {
					t.Errorf("%s: %v had the Type().String()=%q. expected %q", within, v, got, want)
				}
			}
		default:
			t.Errorf("%q is not a test subcommand", test)
		}
	}
	if want := 3 * 4; skipped != want {
		t.Errorf("Skipped %d probes, expected to skip %d", skipped, want)
	}
}

// constString returns the value of a string constant
// or "<not a constant string>" if the value is not a string constant.
func constString(v ssa.Value) string {
	if c, ok := v.(*ssa.Const); ok {
		str := c.Value.String()
		return strings.Trim(str, `"`)
	}
	return "<not a constant string>"
}

// TestMultipleGoversions tests that globals initialized to equivalent
// function literals are compiled based on the different GoVersion in each file.
func TestMultipleGoversions(t *testing.T) {
	var contents = map[string]string{
		"post.go": `
	//go:build go1.22
	package p

	var distinct = func(l []int) {
		for i := range l {
			print(&i)
		}
	}
	`,
		"pre.go": `
	package p

	var same = func(l []int) {
		for i := range l {
			print(&i)
		}
	}
	`,
	}

	fset := token.NewFileSet()
	var files []*ast.File
	for _, fname := range []string{"post.go", "pre.go"} {
		file, err := parser.ParseFile(fset, fname, contents[fname], 0)
		if err != nil {
			t.Fatal(err)
		}
		files = append(files, file)
	}

	pkg := types.NewPackage("p", "")
	conf := &types.Config{Importer: nil, GoVersion: "go1.21"}
	p, _, err := ssautil.BuildPackage(conf, fset, pkg, files, ssa.SanityCheckFunctions)
	if err != nil {
		t.Fatal(err)
	}

	// Test that global is initialized to a function literal that was
	// compiled to have the expected for loop range variable lifetime for i.
	for _, test := range []struct {
		global *ssa.Global
		want   string // basic block to []*ssa.Alloc.
	}{
		{p.Var("same"), "map[entry:[new int (i)]]"},               // i is allocated in the entry block.
		{p.Var("distinct"), "map[rangeindex.body:[new int (i)]]"}, // i is allocated in the body block.
	} {
		// Find the function the test.name global is initialized to.
		var fn *ssa.Function
		for _, b := range p.Func("init").Blocks {
			for _, instr := range b.Instrs {
				if s, ok := instr.(*ssa.Store); ok && s.Addr == test.global {
					fn, _ = s.Val.(*ssa.Function)
				}
			}
		}
		if fn == nil {
			t.Fatalf("Failed to find *ssa.Function for initial value of global %s", test.global)
		}

		allocs := make(map[string][]string) // block comments -> []Alloc
		for _, b := range fn.Blocks {
			for _, instr := range b.Instrs {
				if a, ok := instr.(*ssa.Alloc); ok {
					allocs[b.Comment] = append(allocs[b.Comment], a.String())
				}
			}
		}
		if got := fmt.Sprint(allocs); got != test.want {
			t.Errorf("[%s:=%s] expected the allocations to be in the basic blocks %q, got %q", test.global, fn, test.want, got)
		}
	}
}

// TestRangeOverInt tests that, in a range-over-int (#61405),
// the type of each range var v (identified by print(v) calls)
// has the expected type.
func TestRangeOverInt(t *testing.T) {
	const rangeOverIntSrc = `
		package p

		type I uint8

		func noKey(x int) {
			for range x {
				// does not crash
			}
		}

		func untypedConstantOperand() {
			for i := range 10 {
				print(i) /*@ types("int")*/
			}
		}

		func unsignedOperand(x uint64) {
			for i := range x {
				print(i) /*@ types("uint64")*/
			}
		}

		func namedOperand(x I) {
			for i := range x {
				print(i)  /*@ types("p.I")*/
			}
		}

		func typeparamOperand[T int](x T) {
			for i := range x {
				print(i)  /*@ types("T")*/
			}
		}

		func assignment(x I) {
			var k I
			for k = range x {
				print(k) /*@ types("p.I")*/
			}
		}
	`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", rangeOverIntSrc, parser.ParseComments)
	if err != nil {
		t.Fatal(err)
	}

	pkg := types.NewPackage("p", "")
	conf := &types.Config{}
	p, _, err := ssautil.BuildPackage(conf, fset, pkg, []*ast.File{f}, ssa.SanityCheckFunctions)
	if err != nil {
		t.Fatal(err)
	}

	// Collect all notes in f, i.e. comments starting with "//@ types".
	notes, err := expect.ExtractGo(fset.File(f.Pos()), f)
	if err != nil {
		t.Fatal(err)
	}

	// Collect calls to the built-in print function.
	fns := make(map[*ssa.Function]bool)
	for _, mem := range p.Members {
		if fn, ok := mem.(*ssa.Function); ok {
			fns[fn] = true
		}
	}
	probes := callsTo(fns, "print")
	expectations := matchNotes(fset, notes, probes)

	for call := range probes {
		if expectations[call] == nil {
			t.Errorf("Unmatched call: %v @ %s", call, fset.Position(call.Pos()))
		}
	}

	// Check each expectation.
	for call, note := range expectations {
		var args []string
		for _, a := range call.Args {
			args = append(args, a.Type().String())
		}
		if got, want := fmt.Sprint(args), fmt.Sprint(note.Args); got != want {
			at := fset.Position(call.Pos())
			t.Errorf("%s: arguments to print had types %s, want %s", at, got, want)
			logFunction(t, probes[call])
		}
	}
}

func TestBuildPackageGo120(t *testing.T) {
	tests := []struct {
		name     string
		src      string
		importer types.Importer
	}{
		{"slice to array", "package p; var s []byte; var _ = ([4]byte)(s)", nil},
		{"slice to zero length array", "package p; var s []byte; var _ = ([0]byte)(s)", nil},
		{"slice to zero length array type parameter", "package p; var s []byte; func f[T ~[0]byte]() { tmp := (T)(s); var z T; _ = tmp == z}", nil},
		{"slice to non-zero length array type parameter", "package p; var s []byte; func h[T ~[1]byte | [4]byte]() { tmp := T(s); var z T; _ = tmp == z}", nil},
		{"slice to maybe-zero length array type parameter", "package p; var s []byte; func g[T ~[0]byte | [4]byte]() { tmp := T(s); var z T; _ = tmp == z}", nil},
		{
			"rune sequence to sequence cast patterns", `
			package p
			// Each of fXX functions describes a 1.20 legal cast between sequences of runes
			// as []rune, pointers to rune arrays, rune arrays, or strings.
			//
			// Comments listed given the current emitted instructions [approximately].
			// If multiple conversions are needed, these are separated by |.
			// rune was selected as it leads to string casts (byte is similar).
			// The length 2 is not significant.
			// Multiple array lengths may occur in a cast in practice (including 0).
			func f00[S string, D string](s S)                               { _ = D(s) } // ChangeType
			func f01[S string, D []rune](s S)                               { _ = D(s) } // Convert
			func f02[S string, D []rune | string](s S)                      { _ = D(s) } // ChangeType | Convert
			func f03[S [2]rune, D [2]rune](s S)                             { _ = D(s) } // ChangeType
			func f04[S *[2]rune, D *[2]rune](s S)                           { _ = D(s) } // ChangeType
			func f05[S []rune, D string](s S)                               { _ = D(s) } // Convert
			func f06[S []rune, D [2]rune](s S)                              { _ = D(s) } // SliceToArrayPointer; Deref
			func f07[S []rune, D [2]rune | string](s S)                     { _ = D(s) } // SliceToArrayPointer; Deref | Convert
			func f08[S []rune, D *[2]rune](s S)                             { _ = D(s) } // SliceToArrayPointer
			func f09[S []rune, D *[2]rune | string](s S)                    { _ = D(s) } // SliceToArrayPointer; Deref | Convert
			func f10[S []rune, D *[2]rune | [2]rune](s S)                   { _ = D(s) } // SliceToArrayPointer | SliceToArrayPointer; Deref
			func f11[S []rune, D *[2]rune | [2]rune | string](s S)          { _ = D(s) } // SliceToArrayPointer | SliceToArrayPointer; Deref | Convert
			func f12[S []rune, D []rune](s S)                               { _ = D(s) } // ChangeType
			func f13[S []rune, D []rune | string](s S)                      { _ = D(s) } // Convert | ChangeType
			func f14[S []rune, D []rune | [2]rune](s S)                     { _ = D(s) } // ChangeType | SliceToArrayPointer; Deref
			func f15[S []rune, D []rune | [2]rune | string](s S)            { _ = D(s) } // ChangeType | SliceToArrayPointer; Deref | Convert
			func f16[S []rune, D []rune | *[2]rune](s S)                    { _ = D(s) } // ChangeType | SliceToArrayPointer
			func f17[S []rune, D []rune | *[2]rune | string](s S)           { _ = D(s) } // ChangeType | SliceToArrayPointer | Convert
			func f18[S []rune, D []rune | *[2]rune | [2]rune](s S)          { _ = D(s) } // ChangeType | SliceToArrayPointer | SliceToArrayPointer; Deref
			func f19[S []rune, D []rune | *[2]rune | [2]rune | string](s S) { _ = D(s) } // ChangeType | SliceToArrayPointer | SliceToArrayPointer; Deref | Convert
			func f20[S []rune | string, D string](s S)                      { _ = D(s) } // Convert | ChangeType
			func f21[S []rune | string, D []rune](s S)                      { _ = D(s) } // Convert | ChangeType
			func f22[S []rune | string, D []rune | string](s S)             { _ = D(s) } // ChangeType | Convert | Convert | ChangeType
			func f23[S []rune | [2]rune, D [2]rune](s S)                    { _ = D(s) } // SliceToArrayPointer; Deref | ChangeType
			func f24[S []rune | *[2]rune, D *[2]rune](s S)                  { _ = D(s) } // SliceToArrayPointer | ChangeType
			`, nil,
		},
		{
			"matching named and underlying types", `
			package p
			type a string
			type b string
			func g0[S []rune | a | b, D []rune | a | b](s S)      { _ = D(s) }
			func g1[S []rune | ~string, D []rune | a | b](s S)    { _ = D(s) }
			func g2[S []rune | a | b, D []rune | ~string](s S)    { _ = D(s) }
			func g3[S []rune | ~string, D []rune |~string](s S)   { _ = D(s) }
			`, nil,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			t.Parallel()
			fset := token.NewFileSet()
			f, err := parser.ParseFile(fset, "p.go", tc.src, 0)
			if err != nil {
				t.Error(err)
			}
			files := []*ast.File{f}

			pkg := types.NewPackage("p", "")
			conf := &types.Config{Importer: tc.importer}
			_, _, err = ssautil.BuildPackage(conf, fset, pkg, files, ssa.SanityCheckFunctions)
			if err != nil {
				t.Errorf("unexpected error: %v", err)
			}
		})
	}
}


================================================
FILE: go/ssa/const.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines the Const SSA value type.

import (
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"strconv"

	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

// NewConst returns a new constant of the specified value and type.
// val must be valid according to the specification of Const.Value.
func NewConst(val constant.Value, typ types.Type) *Const {
	if val == nil {
		switch soleTypeKind(typ) {
		case types.IsBoolean:
			val = constant.MakeBool(false)
		case types.IsInteger:
			val = constant.MakeInt64(0)
		case types.IsString:
			val = constant.MakeString("")
		}
	}
	return &Const{typ, val}
}

// soleTypeKind returns a BasicInfo for which constant.Value can
// represent all zero values for the types in the type set.
//
//	types.IsBoolean for false is a representative.
//	types.IsInteger for 0
//	types.IsString for ""
//	0 otherwise.
func soleTypeKind(typ types.Type) types.BasicInfo {
	// State records the set of possible zero values (false, 0, "").
	// Candidates (perhaps all) are eliminated during the type-set
	// iteration, which executes at least once.
	state := types.IsBoolean | types.IsInteger | types.IsString
	underIs(typ, func(ut types.Type) bool {
		var c types.BasicInfo
		if t, ok := ut.(*types.Basic); ok {
			c = t.Info()
		}
		if c&types.IsNumeric != 0 { // int/float/complex
			c = types.IsInteger
		}
		state = state & c
		return state != 0
	})
	return state
}

// intConst returns an 'int' constant that evaluates to i.
// (i is an int64 in case the host is narrower than the target.)
func intConst(i int64) *Const {
	return NewConst(constant.MakeInt64(i), tInt)
}

// stringConst returns a 'string' constant that evaluates to s.
func stringConst(s string) *Const {
	return NewConst(constant.MakeString(s), tString)
}

// zeroConst returns a new "zero" constant of the specified type.
func zeroConst(t types.Type) *Const {
	return NewConst(nil, t)
}

func (c *Const) RelString(from *types.Package) string {
	var s string
	if c.Value == nil {
		s, _ = typesinternal.ZeroString(c.typ, types.RelativeTo(from))
	} else if c.Value.Kind() == constant.String {
		s = constant.StringVal(c.Value)
		const max = 20
		// TODO(adonovan): don't cut a rune in half.
		if len(s) > max {
			s = s[:max-3] + "..." // abbreviate
		}
		s = strconv.Quote(s)
	} else {
		s = c.Value.String()
	}
	return s + ":" + relType(c.Type(), from)
}

func (c *Const) Name() string {
	return c.RelString(nil)
}

func (c *Const) String() string {
	return c.Name()
}

func (c *Const) Type() types.Type {
	return c.typ
}

func (c *Const) Referrers() *[]Instruction {
	return nil
}

func (c *Const) Parent() *Function { return nil }

func (c *Const) Pos() token.Pos {
	return token.NoPos
}

// IsNil returns true if this constant is a nil value of
// a nillable reference type (pointer, slice, channel, map, or function),
// a basic interface type, or
// a type parameter all of whose possible instantiations are themselves nillable.
func (c *Const) IsNil() bool {
	return c.Value == nil && nillable(c.typ)
}

// nillable reports whether *new(T) == nil is legal for type T.
func nillable(t types.Type) bool {
	if typeparams.IsTypeParam(t) {
		return underIs(t, func(u types.Type) bool {
			// empty type set (u==nil) => any underlying types => not nillable
			return u != nil && nillable(u)
		})
	}
	switch t.Underlying().(type) {
	case *types.Pointer, *types.Slice, *types.Chan, *types.Map, *types.Signature:
		return true
	case *types.Interface:
		return true // basic interface.
	default:
		return false
	}
}

// TODO(adonovan): move everything below into golang.org/x/tools/go/ssa/interp.

// Int64 returns the numeric value of this constant truncated to fit
// a signed 64-bit integer.
func (c *Const) Int64() int64 {
	switch x := constant.ToInt(c.Value); x.Kind() {
	case constant.Int:
		if i, ok := constant.Int64Val(x); ok {
			return i
		}
		return 0
	case constant.Float:
		f, _ := constant.Float64Val(x)
		return int64(f)
	}
	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}

// Uint64 returns the numeric value of this constant truncated to fit
// an unsigned 64-bit integer.
func (c *Const) Uint64() uint64 {
	switch x := constant.ToInt(c.Value); x.Kind() {
	case constant.Int:
		if u, ok := constant.Uint64Val(x); ok {
			return u
		}
		return 0
	case constant.Float:
		f, _ := constant.Float64Val(x)
		return uint64(f)
	}
	panic(fmt.Sprintf("unexpected constant value: %T", c.Value))
}

// Float64 returns the numeric value of this constant truncated to fit
// a float64.
func (c *Const) Float64() float64 {
	x := constant.ToFloat(c.Value) // (c.Value == nil) => x.Kind() == Unknown
	f, _ := constant.Float64Val(x)
	return f
}

// Complex128 returns the complex value of this constant truncated to
// fit a complex128.
func (c *Const) Complex128() complex128 {
	x := constant.ToComplex(c.Value) // (c.Value == nil) => x.Kind() == Unknown
	re, _ := constant.Float64Val(constant.Real(x))
	im, _ := constant.Float64Val(constant.Imag(x))
	return complex(re, im)
}


================================================
FILE: go/ssa/const_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"go/ast"
	"go/constant"
	"go/parser"
	"go/token"
	"go/types"
	"math/big"
	"strings"
	"testing"

	"golang.org/x/tools/go/ssa"
)

func TestConstString(t *testing.T) {
	const source = `
	package P

	type Named string

	func fn() (int, bool, string) 
	func gen[T int]() {}
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		expr     string // type expression
		constant any    // constant value
		want     string // expected String() value
	}{
		{"int", int64(0), "0:int"},
		{"int64", int64(0), "0:int64"},
		{"float32", int64(0), "0:float32"},
		{"float32", big.NewFloat(1.5), "1.5:float32"},
		{"bool", false, "false:bool"},
		{"string", "", `"":string`},
		{"Named", "", `"":P.Named`},
		{"struct{x string}", nil, "struct{x string}{}:struct{x string}"},
		{"[]int", nil, "nil:[]int"},
		{"[3]int", nil, "[3]int{}:[3]int"},
		{"*int", nil, "nil:*int"},
		{"interface{}", nil, "nil:interface{}"},
		{"interface{string}", nil, `"":interface{string}`},
		{"interface{int|int64}", nil, "0:interface{int|int64}"},
		{"interface{bool}", nil, "false:interface{bool}"},
		{"interface{bool|int}", nil, "invalid:interface{bool|int}"},
		{"interface{int|string}", nil, "invalid:interface{int|string}"},
		{"interface{bool|string}", nil, "invalid:interface{bool|string}"},
		{"interface{struct{x string}}", nil, "invalid:interface{struct{x string}}"},
		{"interface{int|int64}", int64(1), "1:interface{int|int64}"},
		{"interface{~bool}", true, "true:interface{~bool}"},
		{"interface{Named}", "lorem ipsum", `"lorem ipsum":interface{P.Named}`},
		{"func() (int, bool, string)", nil, "nil:func() (int, bool, string)"},
	} {
		// Eval() expr for its type.
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Fatalf("Eval(%s) failed: %v", test.expr, err)
		}
		var val constant.Value
		if test.constant != nil {
			val = constant.Make(test.constant)
		}
		c := ssa.NewConst(val, tv.Type)
		got := strings.ReplaceAll(c.String(), " | ", "|") // Accept both interface{a | b} and interface{a|b}.
		if got != test.want {
			t.Errorf("ssa.NewConst(%v, %s).String() = %v, want %v", val, tv.Type, got, test.want)
		}
	}

	// Test tuples
	fn := pkg.Scope().Lookup("fn")
	tup := fn.Type().(*types.Signature).Results()
	if got, want := ssa.NewConst(nil, tup).String(), `(0, false, ""):(int, bool, string)`; got != want {
		t.Errorf("ssa.NewConst(%v, %s).String() = %v, want %v", nil, tup, got, want)
	}

	// Test type-param
	gen := pkg.Scope().Lookup("gen")
	tp := gen.Type().(*types.Signature).TypeParams().At(0)
	if got, want := ssa.NewConst(nil, tp).String(), "0:T"; got != want {
		t.Errorf("ssa.NewConst(%v, %s).String() = %v, want %v", nil, tup, got, want)
	}
}


================================================
FILE: go/ssa/create.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file implements the CREATE phase of SSA construction.
// See builder.go for explanation.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"os"
	"sync"

	"golang.org/x/tools/internal/versions"
)

// NewProgram returns a new SSA Program.
//
// mode controls diagnostics and checking during SSA construction.
//
// To construct an SSA program:
//
//   - Call NewProgram to create an empty Program.
//   - Call CreatePackage providing typed syntax for each package
//     you want to build, and call it with types but not
//     syntax for each of those package's direct dependencies.
//   - Call [Package.Build] on each syntax package you wish to build,
//     or [Program.Build] to build all of them.
//
// See the Example tests for simple examples.
func NewProgram(fset *token.FileSet, mode BuilderMode) *Program {
	return &Program{
		Fset:     fset,
		imported: make(map[string]*Package),
		packages: make(map[*types.Package]*Package),
		mode:     mode,
		canon:    newCanonizer(),
		ctxt:     types.NewContext(),
	}
}

// memberFromObject populates package pkg with a member for the
// typechecker object obj.
//
// For objects from Go source code, syntax is the associated syntax
// tree (for funcs and vars only) and goversion defines the
// appropriate interpretation; they will be used during the build
// phase.
func memberFromObject(pkg *Package, obj types.Object, syntax ast.Node, goversion string) {
	name := obj.Name()
	switch obj := obj.(type) {
	case *types.Builtin:
		if pkg.Pkg != types.Unsafe {
			panic("unexpected builtin object: " + obj.String())
		}

	case *types.TypeName:
		if name != "_" {
			pkg.Members[name] = &Type{
				object: obj,
				pkg:    pkg,
			}
		}

	case *types.Const:
		c := &NamedConst{
			object: obj,
			Value:  NewConst(obj.Val(), obj.Type()),
			pkg:    pkg,
		}
		pkg.objects[obj] = c
		if name != "_" {
			pkg.Members[name] = c
		}

	case *types.Var:
		g := &Global{
			Pkg:    pkg,
			name:   name,
			object: obj,
			typ:    types.NewPointer(obj.Type()), // address
			pos:    obj.Pos(),
		}
		pkg.objects[obj] = g
		if name != "_" {
			pkg.Members[name] = g
		}

	case *types.Func:
		sig := obj.Type().(*types.Signature)
		if sig.Recv() == nil && name == "init" {
			pkg.ninit++
			name = fmt.Sprintf("init#%d", pkg.ninit)
		}
		fn := createFunction(pkg.Prog, obj, name, syntax, pkg.info, goversion)
		fn.Pkg = pkg
		pkg.created = append(pkg.created, fn)
		pkg.objects[obj] = fn
		if name != "_" && sig.Recv() == nil {
			pkg.Members[name] = fn // package-level function
		}

	default: // (incl. *types.Package)
		panic("unexpected Object type: " + obj.String())
	}
}

// createFunction creates a function or method. It supports both
// CreatePackage (with or without syntax) and the on-demand creation
// of methods in non-created packages based on their types.Func.
func createFunction(prog *Program, obj *types.Func, name string, syntax ast.Node, info *types.Info, goversion string) *Function {
	sig := obj.Type().(*types.Signature)

	// Collect type parameters.
	var tparams *types.TypeParamList
	if rtparams := sig.RecvTypeParams(); rtparams.Len() > 0 {
		tparams = rtparams // method of generic type
	} else if sigparams := sig.TypeParams(); sigparams.Len() > 0 {
		tparams = sigparams // generic function
	}

	/* declared function/method (from syntax or export data) */
	fn := &Function{
		name:       name,
		object:     obj,
		Signature:  sig,
		build:      (*builder).buildFromSyntax,
		syntax:     syntax,
		info:       info,
		goversion:  goversion,
		pos:        obj.Pos(),
		Pkg:        nil, // may be set by caller
		Prog:       prog,
		typeparams: tparams,
	}
	if fn.syntax == nil {
		fn.Synthetic = "from type information"
		fn.build = (*builder).buildParamsOnly
	}
	if tparams.Len() > 0 {
		fn.generic = new(generic)
	}
	return fn
}

// membersFromDecl populates package pkg with members for each
// typechecker object (var, func, const or type) associated with the
// specified decl.
func membersFromDecl(pkg *Package, decl ast.Decl, goversion string) {
	switch decl := decl.(type) {
	case *ast.GenDecl: // import, const, type or var
		switch decl.Tok {
		case token.CONST:
			for _, spec := range decl.Specs {
				for _, id := range spec.(*ast.ValueSpec).Names {
					memberFromObject(pkg, pkg.info.Defs[id], nil, "")
				}
			}

		case token.VAR:
			for _, spec := range decl.Specs {
				for _, rhs := range spec.(*ast.ValueSpec).Values {
					pkg.initVersion[rhs] = goversion
				}
				for _, id := range spec.(*ast.ValueSpec).Names {
					memberFromObject(pkg, pkg.info.Defs[id], spec, goversion)
				}
			}

		case token.TYPE:
			for _, spec := range decl.Specs {
				id := spec.(*ast.TypeSpec).Name
				memberFromObject(pkg, pkg.info.Defs[id], nil, "")
			}
		}

	case *ast.FuncDecl:
		id := decl.Name
		memberFromObject(pkg, pkg.info.Defs[id], decl, goversion)
	}
}

// CreatePackage creates and returns an SSA Package from the
// specified type-checked, error-free file ASTs, and populates its
// Members mapping.
//
// importable determines whether this package should be returned by a
// subsequent call to ImportedPackage(pkg.Path()).
//
// The real work of building SSA form for each function is not done
// until a subsequent call to Package.Build.
func (prog *Program) CreatePackage(pkg *types.Package, files []*ast.File, info *types.Info, importable bool) *Package {
	if pkg == nil {
		panic("nil pkg") // otherwise pkg.Scope below returns types.Universe!
	}
	p := &Package{
		Prog:    prog,
		Members: make(map[string]Member),
		objects: make(map[types.Object]Member),
		Pkg:     pkg,
		syntax:  info != nil,
		// transient values (cleared after Package.Build)
		info:        info,
		files:       files,
		initVersion: make(map[ast.Expr]string),
	}

	/* synthesized package initializer */
	p.init = &Function{
		name:      "init",
		Signature: new(types.Signature),
		Synthetic: "package initializer",
		Pkg:       p,
		Prog:      prog,
		build:     (*builder).buildPackageInit,
		info:      p.info,
		goversion: "", // See Package.build for details.
	}
	p.Members[p.init.name] = p.init
	p.created = append(p.created, p.init)

	// Allocate all package members: vars, funcs, consts and types.
	if len(files) > 0 {
		// Go source package.
		for _, file := range files {
			goversion := versions.Lang(versions.FileVersion(p.info, file))
			for _, decl := range file.Decls {
				membersFromDecl(p, decl, goversion)
			}
		}
	} else {
		// GC-compiled binary package (or "unsafe")
		// No code.
		// No position information.
		scope := p.Pkg.Scope()
		for _, name := range scope.Names() {
			obj := scope.Lookup(name)
			memberFromObject(p, obj, nil, "")
			if obj, ok := obj.(*types.TypeName); ok {
				// No Unalias: aliases should not duplicate methods.
				if named, ok := obj.Type().(*types.Named); ok {
					for i, n := 0, named.NumMethods(); i < n; i++ {
						memberFromObject(p, named.Method(i), nil, "")
					}
				}
			}
		}
	}

	if prog.mode&BareInits == 0 {
		// Add initializer guard variable.
		initguard := &Global{
			Pkg:  p,
			name: "init$guard",
			typ:  types.NewPointer(tBool),
		}
		p.Members[initguard.Name()] = initguard
	}

	if prog.mode&GlobalDebug != 0 {
		p.SetDebugMode(true)
	}

	if prog.mode&PrintPackages != 0 {
		printMu.Lock()
		p.WriteTo(os.Stdout)
		printMu.Unlock()
	}

	if importable {
		prog.imported[p.Pkg.Path()] = p
	}
	prog.packages[p.Pkg] = p

	return p
}

// printMu serializes printing of Packages/Functions to stdout.
var printMu sync.Mutex

// AllPackages returns a new slice containing all packages created by
// prog.CreatePackage in unspecified order.
func (prog *Program) AllPackages() []*Package {
	pkgs := make([]*Package, 0, len(prog.packages))
	for _, pkg := range prog.packages {
		pkgs = append(pkgs, pkg)
	}
	return pkgs
}

// ImportedPackage returns the importable Package whose PkgPath
// is path, or nil if no such Package has been created.
//
// A parameter to CreatePackage determines whether a package should be
// considered importable. For example, no import declaration can resolve
// to the ad-hoc main package created by 'go build foo.go'.
//
// TODO(adonovan): rethink this function and the "importable" concept;
// most packages are importable. This function assumes that all
// types.Package.Path values are unique within the ssa.Program, which is
// false---yet this function remains very convenient.
// Clients should use (*Program).Package instead where possible.
// SSA doesn't really need a string-keyed map of packages.
//
// Furthermore, the graph of packages may contain multiple variants
// (e.g. "p" vs "p as compiled for q.test"), and each has a different
// view of its dependencies.
func (prog *Program) ImportedPackage(path string) *Package {
	return prog.imported[path]
}

// SetNoReturn sets the predicate used when building the ssa.Program
// prog that reports whether a given function cannot return.
// This may be used to prune spurious control flow edges
// after (e.g.) log.Fatal, improving the precision of analyses.
//
// A typical implementation is the [ctrlflow.CFGs.NoReturn] method from
// [golang.org/x/tools/go/analysis/passes/ctrlflow].
func (prog *Program) SetNoReturn(noReturn func(*types.Func) bool) {
	prog.noReturn = noReturn
}


================================================
FILE: go/ssa/doc.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package ssa defines a representation of the elements of Go programs
// (packages, types, functions, variables and constants) using a
// static single-assignment (SSA) form intermediate representation
// (IR) for the bodies of functions.
//
// For an introduction to SSA form, see
// http://en.wikipedia.org/wiki/Static_single_assignment_form.
// This page provides a broader reading list:
// http://www.dcs.gla.ac.uk/~jsinger/ssa.html.
//
// The level of abstraction of the SSA form is intentionally close to
// the source language to facilitate construction of source analysis
// tools.  It is not intended for machine code generation.
//
// All looping, branching and switching constructs are replaced with
// unstructured control flow.  Higher-level control flow constructs
// such as multi-way branch can be reconstructed as needed; see
// [golang.org/x/tools/go/ssa/ssautil.Switches] for an example.
//
// The simplest way to create the SSA representation of a package is
// to load typed syntax trees using [golang.org/x/tools/go/packages], then
// invoke the [golang.org/x/tools/go/ssa/ssautil.Packages] helper function.
// (See the package-level Examples named LoadPackages and LoadWholeProgram.)
// The resulting [ssa.Program] contains all the packages and their
// members, but SSA code is not created for function bodies until a
// subsequent call to [Package.Build] or [Program.Build].
//
// The builder initially builds a naive SSA form in which all local
// variables are addresses of stack locations with explicit loads and
// stores.  Registerisation of eligible locals and φ-node insertion
// using dominance and dataflow are then performed as a second pass
// called "lifting" to improve the accuracy and performance of
// subsequent analyses; this pass can be skipped by setting the
// NaiveForm builder flag.
//
// The primary interfaces of this package are:
//
//   - [Member]: a named member of a Go package.
//   - [Value]: an expression that yields a value.
//   - [Instruction]: a statement that consumes values and performs computation.
//   - [Node]: a [Value] or [Instruction] (emphasizing its membership in the SSA value graph)
//
// A computation that yields a result implements both the [Value] and
// [Instruction] interfaces.  The following table shows for each
// concrete type which of these interfaces it implements.
//
//	                   Value?          Instruction?      Member?
//	*Alloc                ✔               ✔
//	*BinOp                ✔               ✔
//	*Builtin              ✔
//	*Call                 ✔               ✔
//	*ChangeInterface      ✔               ✔
//	*ChangeType           ✔               ✔
//	*Const                ✔
//	*Convert              ✔               ✔
//	*DebugRef                             ✔
//	*Defer                                ✔
//	*Extract              ✔               ✔
//	*Field                ✔               ✔
//	*FieldAddr            ✔               ✔
//	*FreeVar              ✔
//	*Function             ✔                               ✔ (func)
//	*Global               ✔                               ✔ (var)
//	*Go                                   ✔
//	*If                                   ✔
//	*Index                ✔               ✔
//	*IndexAddr            ✔               ✔
//	*Jump                                 ✔
//	*Lookup               ✔               ✔
//	*MakeChan             ✔               ✔
//	*MakeClosure          ✔               ✔
//	*MakeInterface        ✔               ✔
//	*MakeMap              ✔               ✔
//	*MakeSlice            ✔               ✔
//	*MapUpdate                            ✔
//	*MultiConvert         ✔               ✔
//	*NamedConst                                           ✔ (const)
//	*Next                 ✔               ✔
//	*Panic                                ✔
//	*Parameter            ✔
//	*Phi                  ✔               ✔
//	*Range                ✔               ✔
//	*Return                               ✔
//	*RunDefers                            ✔
//	*Select               ✔               ✔
//	*Send                                 ✔
//	*Slice                ✔               ✔
//	*SliceToArrayPointer  ✔               ✔
//	*Store                                ✔
//	*Type                                                 ✔ (type)
//	*TypeAssert           ✔               ✔
//	*UnOp                 ✔               ✔
//
// Other key types in this package include: [Program], [Package], [Function]
// and [BasicBlock].
//
// The program representation constructed by this package is fully
// resolved internally, i.e. it does not rely on the names of Values,
// Packages, Functions, Types or BasicBlocks for the correct
// interpretation of the program.  Only the identities of objects and
// the topology of the SSA and type graphs are semantically
// significant.  (There is one exception: [types.Id] values, which identify field
// and method names, contain strings.)  Avoidance of name-based
// operations simplifies the implementation of subsequent passes and
// can make them very efficient.  Many objects are nonetheless named
// to aid in debugging, but it is not essential that the names be
// either accurate or unambiguous.  The public API exposes a number of
// name-based maps for client convenience.
//
// The [golang.org/x/tools/go/ssa/ssautil] package provides various
// helper functions, for example to simplify loading a Go program into
// SSA form.
//
// TODO(adonovan): write a how-to document for all the various cases
// of trying to determine corresponding elements across the four
// domains of source locations, ast.Nodes, types.Objects,
// ssa.Values/Instructions.
package ssa // import "golang.org/x/tools/go/ssa"


================================================
FILE: go/ssa/dom.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines algorithms related to dominance.

// Dominator tree construction ----------------------------------------
//
// We use the algorithm described in Lengauer & Tarjan. 1979.  A fast
// algorithm for finding dominators in a flowgraph.
// http://doi.acm.org/10.1145/357062.357071
//
// We also apply the optimizations to SLT described in Georgiadis et
// al, Finding Dominators in Practice, JGAA 2006,
// http://jgaa.info/accepted/2006/GeorgiadisTarjanWerneck2006.10.1.pdf
// to avoid the need for buckets of size > 1.

import (
	"bytes"
	"fmt"
	"math/big"
	"os"
	"slices"
	"sort"
)

// Idom returns the block that immediately dominates b:
// its parent in the dominator tree, if any.
// Neither the entry node (b.Index==0) nor recover node
// (b==b.Parent().Recover()) have a parent.
func (b *BasicBlock) Idom() *BasicBlock { return b.dom.idom }

// Dominees returns the list of blocks that b immediately dominates:
// its children in the dominator tree.
func (b *BasicBlock) Dominees() []*BasicBlock { return b.dom.children }

// Dominates reports whether b dominates c.
func (b *BasicBlock) Dominates(c *BasicBlock) bool {
	return b.dom.pre <= c.dom.pre && c.dom.post <= b.dom.post
}

// DomPreorder returns a new slice containing the blocks of f
// in a preorder traversal of the dominator tree.
func (f *Function) DomPreorder() []*BasicBlock {
	slice := slices.Clone(f.Blocks)
	sort.Slice(slice, func(i, j int) bool {
		return slice[i].dom.pre < slice[j].dom.pre
	})
	return slice
}

// DomPostorder returns a new slice containing the blocks of f
// in a postorder traversal of the dominator tree.
// (This is not the same as a postdominance order.)
func (f *Function) DomPostorder() []*BasicBlock {
	slice := slices.Clone(f.Blocks)
	sort.Slice(slice, func(i, j int) bool {
		return slice[i].dom.post < slice[j].dom.post
	})
	return slice
}

// domInfo contains a BasicBlock's dominance information.
type domInfo struct {
	idom      *BasicBlock   // immediate dominator (parent in domtree)
	children  []*BasicBlock // nodes immediately dominated by this one
	pre, post int32         // pre- and post-order numbering within domtree
}

// ltState holds the working state for Lengauer-Tarjan algorithm
// (during which domInfo.pre is repurposed for CFG DFS preorder number).
type ltState struct {
	// Each slice is indexed by b.Index.
	sdom     []*BasicBlock // b's semidominator
	parent   []*BasicBlock // b's parent in DFS traversal of CFG
	ancestor []*BasicBlock // b's ancestor with least sdom
}

// dfs implements the depth-first search part of the LT algorithm.
func (lt *ltState) dfs(v *BasicBlock, i int32, preorder []*BasicBlock) int32 {
	preorder[i] = v
	v.dom.pre = i // For now: DFS preorder of spanning tree of CFG
	i++
	lt.sdom[v.Index] = v
	lt.link(nil, v)
	for _, w := range v.Succs {
		if lt.sdom[w.Index] == nil {
			lt.parent[w.Index] = v
			i = lt.dfs(w, i, preorder)
		}
	}
	return i
}

// eval implements the EVAL part of the LT algorithm.
func (lt *ltState) eval(v *BasicBlock) *BasicBlock {
	// TODO(adonovan): opt: do path compression per simple LT.
	u := v
	for ; lt.ancestor[v.Index] != nil; v = lt.ancestor[v.Index] {
		if lt.sdom[v.Index].dom.pre < lt.sdom[u.Index].dom.pre {
			u = v
		}
	}
	return u
}

// link implements the LINK part of the LT algorithm.
func (lt *ltState) link(v, w *BasicBlock) {
	lt.ancestor[w.Index] = v
}

// buildDomTree computes the dominator tree of f using the LT algorithm.
// Precondition: all blocks are reachable (e.g. optimizeBlocks has been run).
func buildDomTree(f *Function) {
	// The step numbers refer to the original LT paper; the
	// reordering is due to Georgiadis.

	// Clear any previous domInfo.
	for _, b := range f.Blocks {
		b.dom = domInfo{}
	}

	n := len(f.Blocks)
	// Allocate space for 5 contiguous [n]*BasicBlock arrays:
	// sdom, parent, ancestor, preorder, buckets.
	space := make([]*BasicBlock, 5*n)
	lt := ltState{
		sdom:     space[0:n],
		parent:   space[n : 2*n],
		ancestor: space[2*n : 3*n],
	}

	// Step 1.  Number vertices by depth-first preorder.
	preorder := space[3*n : 4*n]
	root := f.Blocks[0]
	prenum := lt.dfs(root, 0, preorder)
	recover := f.Recover
	if recover != nil {
		lt.dfs(recover, prenum, preorder)
	}

	buckets := space[4*n : 5*n]
	copy(buckets, preorder)

	// In reverse preorder...
	for i := int32(n) - 1; i > 0; i-- {
		w := preorder[i]

		// Step 3. Implicitly define the immediate dominator of each node.
		for v := buckets[i]; v != w; v = buckets[v.dom.pre] {
			u := lt.eval(v)
			if lt.sdom[u.Index].dom.pre < i {
				v.dom.idom = u
			} else {
				v.dom.idom = w
			}
		}

		// Step 2. Compute the semidominators of all nodes.
		lt.sdom[w.Index] = lt.parent[w.Index]
		for _, v := range w.Preds {
			u := lt.eval(v)
			if lt.sdom[u.Index].dom.pre < lt.sdom[w.Index].dom.pre {
				lt.sdom[w.Index] = lt.sdom[u.Index]
			}
		}

		lt.link(lt.parent[w.Index], w)

		if lt.parent[w.Index] == lt.sdom[w.Index] {
			w.dom.idom = lt.parent[w.Index]
		} else {
			buckets[i] = buckets[lt.sdom[w.Index].dom.pre]
			buckets[lt.sdom[w.Index].dom.pre] = w
		}
	}

	// The final 'Step 3' is now outside the loop.
	for v := buckets[0]; v != root; v = buckets[v.dom.pre] {
		v.dom.idom = root
	}

	// Step 4. Explicitly define the immediate dominator of each
	// node, in preorder.
	for _, w := range preorder[1:] {
		if w == root || w == recover {
			w.dom.idom = nil
		} else {
			if w.dom.idom != lt.sdom[w.Index] {
				w.dom.idom = w.dom.idom.dom.idom
			}
			// Calculate Children relation as inverse of Idom.
			w.dom.idom.dom.children = append(w.dom.idom.dom.children, w)
		}
	}

	pre, post := numberDomTree(root, 0, 0)
	if recover != nil {
		numberDomTree(recover, pre, post)
	}

	// printDomTreeDot(os.Stderr, f)        // debugging
	// printDomTreeText(os.Stderr, root, 0) // debugging

	if f.Prog.mode&SanityCheckFunctions != 0 {
		sanityCheckDomTree(f)
	}
}

// numberDomTree sets the pre- and post-order numbers of a depth-first
// traversal of the dominator tree rooted at v.  These are used to
// answer dominance queries in constant time.
func numberDomTree(v *BasicBlock, pre, post int32) (int32, int32) {
	v.dom.pre = pre
	pre++
	for _, child := range v.dom.children {
		pre, post = numberDomTree(child, pre, post)
	}
	v.dom.post = post
	post++
	return pre, post
}

// Testing utilities ----------------------------------------

// sanityCheckDomTree checks the correctness of the dominator tree
// computed by the LT algorithm by comparing against the dominance
// relation computed by a naive Kildall-style forward dataflow
// analysis (Algorithm 10.16 from the "Dragon" book).
func sanityCheckDomTree(f *Function) {
	n := len(f.Blocks)

	// D[i] is the set of blocks that dominate f.Blocks[i],
	// represented as a bit-set of block indices.
	D := make([]big.Int, n)

	one := big.NewInt(1)

	// all is the set of all blocks; constant.
	var all big.Int
	all.Set(one).Lsh(&all, uint(n)).Sub(&all, one)

	// Initialization.
	for i, b := range f.Blocks {
		if i == 0 || b == f.Recover {
			// A root is dominated only by itself.
			D[i].SetBit(&D[0], 0, 1)
		} else {
			// All other blocks are (initially) dominated
			// by every block.
			D[i].Set(&all)
		}
	}

	// Iteration until fixed point.
	for changed := true; changed; {
		changed = false
		for i, b := range f.Blocks {
			if i == 0 || b == f.Recover {
				continue
			}
			// Compute intersection across predecessors.
			var x big.Int
			x.Set(&all)
			for _, pred := range b.Preds {
				x.And(&x, &D[pred.Index])
			}
			x.SetBit(&x, i, 1) // a block always dominates itself.
			if D[i].Cmp(&x) != 0 {
				D[i].Set(&x)
				changed = true
			}
		}
	}

	// Check the entire relation.  O(n^2).
	// The Recover block (if any) must be treated specially so we skip it.
	ok := true
	for i := range n {
		for j := range n {
			b, c := f.Blocks[i], f.Blocks[j]
			if c == f.Recover {
				continue
			}
			actual := b.Dominates(c)
			expected := D[j].Bit(i) == 1
			if actual != expected {
				fmt.Fprintf(os.Stderr, "dominates(%s, %s)==%t, want %t\n", b, c, actual, expected)
				ok = false
			}
		}
	}

	preorder := f.DomPreorder()
	for _, b := range f.Blocks {
		if got := preorder[b.dom.pre]; got != b {
			fmt.Fprintf(os.Stderr, "preorder[%d]==%s, want %s\n", b.dom.pre, got, b)
			ok = false
		}
	}

	if !ok {
		panic("sanityCheckDomTree failed for " + f.String())
	}

}

// Printing functions ----------------------------------------

// printDomTreeText prints the dominator tree as text, using indentation.
func printDomTreeText(buf *bytes.Buffer, v *BasicBlock, indent int) {
	fmt.Fprintf(buf, "%*s%s\n", 4*indent, "", v)
	for _, child := range v.dom.children {
		printDomTreeText(buf, child, indent+1)
	}
}

// printDomTreeDot prints the dominator tree of f in AT&T GraphViz
// (.dot) format.
// (unused; retained for debugging)
func printDomTreeDot(buf *bytes.Buffer, f *Function) {
	fmt.Fprintln(buf, "//", f)
	fmt.Fprintln(buf, "digraph domtree {")
	for i, b := range f.Blocks {
		v := b.dom
		fmt.Fprintf(buf, "\tn%d [label=\"%s (%d, %d)\",shape=\"rectangle\"];\n", v.pre, b, v.pre, v.post)
		// TODO(adonovan): improve appearance of edges
		// belonging to both dominator tree and CFG.

		// Dominator tree edge.
		if i != 0 {
			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"solid\",weight=100];\n", v.idom.dom.pre, v.pre)
		}
		// CFG edges.
		for _, pred := range b.Preds {
			fmt.Fprintf(buf, "\tn%d -> n%d [style=\"dotted\",weight=0];\n", pred.dom.pre, v.pre)
		}
	}
	fmt.Fprintln(buf, "}")
}


================================================
FILE: go/ssa/dom_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"fmt"
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
)

func TestDominatorOrder(t *testing.T) {
	testenv.NeedsGoBuild(t) // for go/packages

	const src = `package p

func f(cond bool) {
	// (Print operands match BasicBlock IDs.)
	print(0)
	if cond {
		print(1)
	} else {
		print(2)
	}
	print(3)
}
`
	dir := t.TempDir()
	cfg := &packages.Config{
		Dir:  dir,
		Mode: packages.LoadSyntax,
		Overlay: map[string][]byte{
			filepath.Join(dir, "p.go"): []byte(src),
		},
	}
	initial, err := packages.Load(cfg, "./p.go")
	if err != nil {
		t.Fatal(err)
	}
	if packages.PrintErrors(initial) > 0 {
		t.Fatal("packages contain errors")
	}
	_, pkgs := ssautil.Packages(initial, 0)
	p := pkgs[0]
	p.Build()
	f := p.Func("f")

	if got, want := fmt.Sprint(f.DomPreorder()), "[0 1 2 3]"; got != want {
		t.Errorf("DomPreorder: got %v, want %s", got, want)
	}
	if got, want := fmt.Sprint(f.DomPostorder()), "[1 2 3 0]"; got != want {
		t.Errorf("DomPostorder: got %v, want %s", got, want)
	}
}


================================================
FILE: go/ssa/emit.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// Helpers for emitting SSA instructions.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/internal/typeparams"
)

// emitAlloc emits to f a new Alloc instruction allocating a variable
// of type typ.
//
// The caller must set Alloc.Heap=true (for a heap-allocated variable)
// or add the Alloc to f.Locals (for a frame-allocated variable).
//
// During building, a variable in f.Locals may have its Heap flag
// set when it is discovered that its address is taken.
// These Allocs are removed from f.Locals at the end.
//
// The builder should generally call one of the emit{New,Local,LocalVar} wrappers instead.
func emitAlloc(f *Function, typ types.Type, pos token.Pos, comment string) *Alloc {
	v := &Alloc{Comment: comment}
	v.setType(types.NewPointer(typ))
	v.setPos(pos)
	f.emit(v)
	return v
}

// emitNew emits to f a new Alloc instruction heap-allocating a
// variable of type typ. pos is the optional source location.
func emitNew(f *Function, typ types.Type, pos token.Pos, comment string) *Alloc {
	alloc := emitAlloc(f, typ, pos, comment)
	alloc.Heap = true
	return alloc
}

// emitLocal creates a local var for (t, pos, comment) and
// emits an Alloc instruction for it.
//
// (Use this function or emitNew for synthetic variables;
// for source-level variables in the same function, use emitLocalVar.)
func emitLocal(f *Function, t types.Type, pos token.Pos, comment string) *Alloc {
	local := emitAlloc(f, t, pos, comment)
	f.Locals = append(f.Locals, local)
	return local
}

// emitLocalVar creates a local var for v and emits an Alloc instruction for it.
// Subsequent calls to f.lookup(v) return it.
// It applies the appropriate generic instantiation to the type.
func emitLocalVar(f *Function, v *types.Var) *Alloc {
	alloc := emitLocal(f, f.typ(v.Type()), v.Pos(), v.Name())
	f.vars[v] = alloc
	return alloc
}

// emitLoad emits to f an instruction to load the address addr into a
// new temporary, and returns the value so defined.
func emitLoad(f *Function, addr Value) *UnOp {
	v := &UnOp{Op: token.MUL, X: addr}
	v.setType(typeparams.MustDeref(addr.Type()))
	f.emit(v)
	return v
}

// emitDebugRef emits to f a DebugRef pseudo-instruction associating
// expression e with value v.
func emitDebugRef(f *Function, e ast.Expr, v Value, isAddr bool) {
	if !f.debugInfo() {
		return // debugging not enabled
	}
	if v == nil || e == nil {
		panic("nil")
	}
	var obj types.Object
	e = ast.Unparen(e)
	if id, ok := e.(*ast.Ident); ok {
		if isBlankIdent(id) {
			return
		}
		obj = f.objectOf(id)
		switch obj.(type) {
		case *types.Nil, *types.Const, *types.Builtin:
			return
		}
	}
	f.emit(&DebugRef{
		X:      v,
		Expr:   e,
		IsAddr: isAddr,
		object: obj,
	})
}

// emitArith emits to f code to compute the binary operation op(x, y)
// where op is an eager shift, logical or arithmetic operation.
// (Use emitCompare() for comparisons and Builder.logicalBinop() for
// non-eager operations.)
func emitArith(f *Function, op token.Token, x, y Value, t types.Type, pos token.Pos) Value {
	switch op {
	case token.SHL, token.SHR:
		x = emitConv(f, x, t)
		// y may be signed or an 'untyped' constant.

		// There is a runtime panic if y is signed and <0. Instead of inserting a check for y<0
		// and converting to an unsigned value (like the compiler) leave y as is.

		if isUntyped(y.Type().Underlying()) {
			// Untyped conversion:
			// Spec https://go.dev/ref/spec#Operators:
			// The right operand in a shift expression must have integer type or be an untyped constant
			// representable by a value of type uint.
			y = emitConv(f, y, types.Typ[types.Uint])
		}

	case token.ADD, token.SUB, token.MUL, token.QUO, token.REM, token.AND, token.OR, token.XOR, token.AND_NOT:
		x = emitConv(f, x, t)
		y = emitConv(f, y, t)

	default:
		panic("illegal op in emitArith: " + op.String())

	}
	v := &BinOp{
		Op: op,
		X:  x,
		Y:  y,
	}
	v.setPos(pos)
	v.setType(t)
	return f.emit(v)
}

// emitCompare emits to f code compute the boolean result of
// comparison 'x op y'.
func emitCompare(f *Function, op token.Token, x, y Value, pos token.Pos) Value {
	xt := x.Type().Underlying()
	yt := y.Type().Underlying()

	// Special case to optimise a tagless SwitchStmt so that
	// these are equivalent
	//   switch { case e: ...}
	//   switch true { case e: ... }
	//   if e==true { ... }
	// even in the case when e's type is an interface.
	// TODO(adonovan): opt: generalise to x==true, false!=y, etc.
	if x == vTrue && op == token.EQL {
		if yt, ok := yt.(*types.Basic); ok && yt.Info()&types.IsBoolean != 0 {
			return y
		}
	}

	if types.Identical(xt, yt) {
		// no conversion necessary
	} else if isNonTypeParamInterface(x.Type()) {
		y = emitConv(f, y, x.Type())
	} else if isNonTypeParamInterface(y.Type()) {
		x = emitConv(f, x, y.Type())
	} else if _, ok := x.(*Const); ok {
		x = emitConv(f, x, y.Type())
	} else if _, ok := y.(*Const); ok {
		y = emitConv(f, y, x.Type())
	} else {
		// other cases, e.g. channels.  No-op.
	}

	v := &BinOp{
		Op: op,
		X:  x,
		Y:  y,
	}
	v.setPos(pos)
	v.setType(tBool)
	return f.emit(v)
}

// isValuePreserving returns true if a conversion from ut_src to
// ut_dst is value-preserving, i.e. just a change of type.
// Precondition: neither argument is a named or alias type.
func isValuePreserving(ut_src, ut_dst types.Type) bool {
	// Identical underlying types?
	if types.IdenticalIgnoreTags(ut_dst, ut_src) {
		return true
	}

	switch ut_dst.(type) {
	case *types.Chan:
		// Conversion between channel types?
		_, ok := ut_src.(*types.Chan)
		return ok

	case *types.Pointer:
		// Conversion between pointers with identical base types?
		_, ok := ut_src.(*types.Pointer)
		return ok
	}
	return false
}

// emitConv emits to f code to convert Value val to exactly type typ,
// and returns the converted value.  Implicit conversions are required
// by language assignability rules in assignments, parameter passing,
// etc.
func emitConv(f *Function, val Value, typ types.Type) Value {
	t_src := val.Type()

	// Identical types?  Conversion is a no-op.
	if types.Identical(t_src, typ) {
		return val
	}
	ut_dst := typ.Underlying()
	ut_src := t_src.Underlying()

	// Conversion to, or construction of a value of, an interface type?
	if isNonTypeParamInterface(typ) {
		// Interface name change?
		if isValuePreserving(ut_src, ut_dst) {
			c := &ChangeType{X: val}
			c.setType(typ)
			return f.emit(c)
		}

		// Assignment from one interface type to another?
		if isNonTypeParamInterface(t_src) {
			c := &ChangeInterface{X: val}
			c.setType(typ)
			return f.emit(c)
		}

		// Untyped nil constant?  Return interface-typed nil constant.
		if ut_src == tUntypedNil {
			return zeroConst(typ)
		}

		// Convert (non-nil) "untyped" literals to their default type.
		if t, ok := ut_src.(*types.Basic); ok && t.Info()&types.IsUntyped != 0 {
			val = emitConv(f, val, types.Default(ut_src))
		}

		// Record the types of operands to MakeInterface, if
		// non-parameterized, as they are the set of runtime types.
		t := val.Type()
		if f.typeparams.Len() == 0 || !f.Prog.isParameterized(t) {
			addMakeInterfaceType(f.Prog, t)
		}

		mi := &MakeInterface{X: val}
		mi.setType(typ)
		return f.emit(mi)
	}

	// conversionCase describes an instruction pattern that maybe emitted to
	// model d <- s for d in dst_terms and s in src_terms.
	// Multiple conversions can match the same pattern.
	type conversionCase uint8
	const (
		changeType conversionCase = 1 << iota
		sliceToArray
		sliceToArrayPtr
		sliceTo0Array
		sliceTo0ArrayPtr
		convert
	)
	// classify the conversion case of a source type us to a destination type ud.
	// us and ud are underlying types (not *Named or *Alias)
	classify := func(us, ud types.Type) conversionCase {
		// Just a change of type, but not value or representation?
		if isValuePreserving(us, ud) {
			return changeType
		}

		// Conversion from slice to array or slice to array pointer?
		if slice, ok := us.(*types.Slice); ok {
			var arr *types.Array
			var ptr bool
			// Conversion from slice to array pointer?
			switch d := ud.(type) {
			case *types.Array:
				arr = d
			case *types.Pointer:
				arr, _ = d.Elem().Underlying().(*types.Array)
				ptr = true
			}
			if arr != nil && types.Identical(slice.Elem(), arr.Elem()) {
				if arr.Len() == 0 {
					if ptr {
						return sliceTo0ArrayPtr
					} else {
						return sliceTo0Array
					}
				}
				if ptr {
					return sliceToArrayPtr
				} else {
					return sliceToArray
				}
			}
		}

		// The only remaining case in well-typed code is a representation-
		// changing conversion of basic types (possibly with []byte/[]rune).
		if !isBasic(us) && !isBasic(ud) {
			panic(fmt.Sprintf("in %s: cannot convert term %s (%s [within %s]) to type %s [within %s]", f, val, val.Type(), us, typ, ud))
		}
		return convert
	}

	var classifications conversionCase
	underIs(ut_src, func(us types.Type) bool {
		return underIs(ut_dst, func(ud types.Type) bool {
			if us != nil && ud != nil {
				classifications |= classify(us, ud)
			}
			return classifications != 0
		})
	})
	if classifications == 0 {
		panic(fmt.Sprintf("in %s: cannot convert %s (%s) to %s", f, val, val.Type(), typ))
	}

	// Conversion of a compile-time constant value?
	if c, ok := val.(*Const); ok {
		// Conversion to a basic type?
		if isBasic(ut_dst) {
			// Conversion of a compile-time constant to
			// another constant type results in a new
			// constant of the destination type and
			// (initially) the same abstract value.
			// We don't truncate the value yet.
			return NewConst(c.Value, typ)
		}
		// Can we always convert from zero value without panicking?
		const mayPanic = sliceToArray | sliceToArrayPtr
		if c.Value == nil && classifications&mayPanic == 0 {
			return NewConst(nil, typ)
		}

		// We're converting from constant to non-constant type,
		// e.g. string -> []byte/[]rune.
	}

	switch classifications {
	case changeType: // representation-preserving change
		c := &ChangeType{X: val}
		c.setType(typ)
		return f.emit(c)

	case sliceToArrayPtr, sliceTo0ArrayPtr: // slice to array pointer
		c := &SliceToArrayPointer{X: val}
		c.setType(typ)
		return f.emit(c)

	case sliceToArray: // slice to arrays (not zero-length)
		ptype := types.NewPointer(typ)
		p := &SliceToArrayPointer{X: val}
		p.setType(ptype)
		x := f.emit(p)
		unOp := &UnOp{Op: token.MUL, X: x}
		unOp.setType(typ)
		return f.emit(unOp)

	case sliceTo0Array: // slice to zero-length arrays (constant)
		return zeroConst(typ)

	case convert: // representation-changing conversion
		c := &Convert{X: val}
		c.setType(typ)
		return f.emit(c)

	default: // The conversion represents a cross product.
		c := &MultiConvert{X: val, from: t_src, to: typ}
		c.setType(typ)
		return f.emit(c)
	}
}

// emitTypeCoercion emits to f code to coerce the type of a
// Value v to exactly type typ, and returns the coerced value.
//
// Requires that coercing v.Typ() to typ is a value preserving change.
//
// Currently used only when v.Type() is a type instance of typ or vice versa.
// A type v is a type instance of a type t if there exists a
// type parameter substitution σ s.t. σ(v) == t. Example:
//
//	σ(func(T) T) == func(int) int for σ == [T ↦ int]
//
// This happens in instantiation wrappers for conversion
// from an instantiation to a parameterized type (and vice versa)
// with σ substituting f.typeparams by f.typeargs.
func emitTypeCoercion(f *Function, v Value, typ types.Type) Value {
	if types.Identical(v.Type(), typ) {
		return v // no coercion needed
	}
	// TODO(taking): for instances should we record which side is the instance?
	c := &ChangeType{
		X: v,
	}
	c.setType(typ)
	f.emit(c)
	return c
}

// emitStore emits to f an instruction to store value val at location
// addr, applying implicit conversions as required by assignability rules.
func emitStore(f *Function, addr, val Value, pos token.Pos) *Store {
	typ := typeparams.MustDeref(addr.Type())
	s := &Store{
		Addr: addr,
		Val:  emitConv(f, val, typ),
		pos:  pos,
	}
	f.emit(s)
	return s
}

// emitJump emits to f a jump to target, and updates the control-flow graph.
// Postcondition: f.currentBlock is nil.
func emitJump(f *Function, target *BasicBlock) {
	b := f.currentBlock
	b.emit(new(Jump))
	addEdge(b, target)
	f.currentBlock = nil
}

// emitIf emits to f a conditional jump to tblock or fblock based on
// cond, and updates the control-flow graph.
// Postcondition: f.currentBlock is nil.
func emitIf(f *Function, cond Value, tblock, fblock *BasicBlock) {
	b := f.currentBlock
	b.emit(&If{Cond: cond})
	addEdge(b, tblock)
	addEdge(b, fblock)
	f.currentBlock = nil
}

// emitExtract emits to f an instruction to extract the index'th
// component of tuple.  It returns the extracted value.
func emitExtract(f *Function, tuple Value, index int) Value {
	e := &Extract{Tuple: tuple, Index: index}
	e.setType(tuple.Type().(*types.Tuple).At(index).Type())
	return f.emit(e)
}

// emitTypeAssert emits to f a type assertion value := x.(t) and
// returns the value.  x.Type() must be an interface.
func emitTypeAssert(f *Function, x Value, t types.Type, pos token.Pos) Value {
	a := &TypeAssert{X: x, AssertedType: t}
	a.setPos(pos)
	a.setType(t)
	return f.emit(a)
}

// emitTypeTest emits to f a type test value,ok := x.(t) and returns
// a (value, ok) tuple.  x.Type() must be an interface.
func emitTypeTest(f *Function, x Value, t types.Type, pos token.Pos) Value {
	a := &TypeAssert{
		X:            x,
		AssertedType: t,
		CommaOk:      true,
	}
	a.setPos(pos)
	a.setType(types.NewTuple(
		newVar("value", t),
		varOk,
	))
	return f.emit(a)
}

// emitTailCall emits to f a function call in tail position.  The
// caller is responsible for all fields of 'call' except its type.
// Intended for wrapper methods.
// Precondition: f does/will not use deferred procedure calls.
// Postcondition: f.currentBlock is nil.
func emitTailCall(f *Function, call *Call) {
	tresults := f.Signature.Results()
	nr := tresults.Len()
	if nr == 1 {
		call.typ = tresults.At(0).Type()
	} else {
		call.typ = tresults
	}
	tuple := emitCall(f, call)
	var ret Return
	switch nr {
	case 0:
		// no-op
	case 1:
		ret.Results = []Value{tuple}
	default:
		for i := range nr {
			v := emitExtract(f, tuple, i)
			// TODO(adonovan): in principle, this is required:
			//   v = emitConv(f, o.Type, f.Signature.Results[i].Type)
			// but in practice emitTailCall is only used when
			// the types exactly match.
			ret.Results = append(ret.Results, v)
		}
	}
	f.emit(&ret)
	f.currentBlock = nil
}

// emitCall emits a call instruction. If the callee is "no return",
// it also emits a panic to eliminate infeasible CFG edges.
func emitCall(fn *Function, call *Call) Value {
	res := fn.emit(call)

	callee := call.Call.StaticCallee()
	if callee != nil &&
		callee.object != nil &&
		fn.Prog.noReturn != nil &&
		fn.Prog.noReturn(callee.object) {
		// Call cannot return. Insert a panic after it.
		fn.emit(&Panic{
			X:   emitConv(fn, vNoReturn, tEface),
			pos: call.Pos(),
		})
		fn.currentBlock = fn.newBasicBlock("unreachable.noreturn")
	}

	return res
}

// emitImplicitSelections emits to f code to apply the sequence of
// implicit field selections specified by indices to base value v, and
// returns the selected value.
//
// If v is the address of a struct, the result will be the address of
// a field; if it is the value of a struct, the result will be the
// value of a field.
func emitImplicitSelections(f *Function, v Value, indices []int, pos token.Pos) Value {
	for _, index := range indices {
		if isPointerCore(v.Type()) {
			fld := fieldOf(typeparams.MustDeref(v.Type()), index)
			instr := &FieldAddr{
				X:     v,
				Field: index,
			}
			instr.setPos(pos)
			instr.setType(types.NewPointer(fld.Type()))
			v = f.emit(instr)
			// Load the field's value iff indirectly embedded.
			if isPointerCore(fld.Type()) {
				v = emitLoad(f, v)
			}
		} else {
			fld := fieldOf(v.Type(), index)
			instr := &Field{
				X:     v,
				Field: index,
			}
			instr.setPos(pos)
			instr.setType(fld.Type())
			v = f.emit(instr)
		}
	}
	return v
}

// emitFieldSelection emits to f code to select the index'th field of v.
//
// If wantAddr, the input must be a pointer-to-struct and the result
// will be the field's address; otherwise the result will be the
// field's value.
// Ident id is used for position and debug info.
func emitFieldSelection(f *Function, v Value, index int, wantAddr bool, id *ast.Ident) Value {
	if isPointerCore(v.Type()) {
		fld := fieldOf(typeparams.MustDeref(v.Type()), index)
		instr := &FieldAddr{
			X:     v,
			Field: index,
		}
		instr.setPos(id.Pos())
		instr.setType(types.NewPointer(fld.Type()))
		v = f.emit(instr)
		// Load the field's value iff we don't want its address.
		if !wantAddr {
			v = emitLoad(f, v)
		}
	} else {
		fld := fieldOf(v.Type(), index)
		instr := &Field{
			X:     v,
			Field: index,
		}
		instr.setPos(id.Pos())
		instr.setType(fld.Type())
		v = f.emit(instr)
	}
	emitDebugRef(f, id, v, wantAddr)
	return v
}

// createRecoverBlock emits to f a block of code to return after a
// recovered panic, and sets f.Recover to it.
//
// If f's result parameters are named, the code loads and returns
// their current values, otherwise it returns the zero values of their
// type.
//
// Idempotent.
func createRecoverBlock(f *Function) {
	if f.Recover != nil {
		return // already created
	}
	saved := f.currentBlock

	f.Recover = f.newBasicBlock("recover")
	f.currentBlock = f.Recover

	var results []Value
	// Reload NRPs to form value tuple.
	for _, nr := range f.results {
		results = append(results, emitLoad(f, nr))
	}

	f.emit(&Return{Results: results})

	f.currentBlock = saved
}


================================================
FILE: go/ssa/example_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !android && !ios && (unix || aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris || plan9 || windows)

package ssa_test

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"log"
	"os"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

const hello = `
package main

import "fmt"

const message = "Hello, World!"

func main() {
	fmt.Println(message)
}
`

// This program demonstrates how to run the SSA builder on a single
// package of one or more already-parsed files. Its dependencies are
// loaded from compiler export data. This is what you'd typically use
// for a compiler; it does not depend on the obsolete
// [golang.org/x/tools/go/loader].
//
// It shows the printed representation of packages, functions, and
// instructions.  Within the function listing, the name of each
// BasicBlock such as ".0.entry" is printed left-aligned, followed by
// the block's Instructions.
//
// For each instruction that defines an SSA virtual register
// (i.e. implements Value), the type of that value is shown in the
// right column.
//
// Build and run the ssadump.go program if you want a standalone tool
// with similar functionality. It is located at
// [golang.org/x/tools/cmd/ssadump].
//
// Use ssautil.BuildPackage only if you have parsed--but not
// type-checked--syntax trees. Typically, clients already have typed
// syntax, perhaps obtained from golang.org/x/tools/go/packages.
// In that case, see the other examples for simpler approaches.
func Example_buildPackage() {
	// Parse the source files.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", hello, parser.ParseComments)
	if err != nil {
		fmt.Print(err) // parse error
		return
	}
	files := []*ast.File{f}

	// Create the type-checker's package.
	pkg := types.NewPackage("hello", "")

	// Type-check the package, load dependencies.
	// Create and build the SSA program.
	hello, _, err := ssautil.BuildPackage(
		&types.Config{Importer: importer.Default()}, fset, pkg, files, ssa.SanityCheckFunctions)
	if err != nil {
		fmt.Print(err) // type error in some package
		return
	}

	// Print out the package.
	hello.WriteTo(os.Stdout)

	// Print out the package-level functions.
	hello.Func("init").WriteTo(os.Stdout)
	hello.Func("main").WriteTo(os.Stdout)

	// Output:
	//
	// package hello:
	//   func  init       func()
	//   var   init$guard bool
	//   func  main       func()
	//   const message    message = "Hello, World!":untyped string
	//
	// # Name: hello.init
	// # Package: hello
	// # Synthetic: package initializer
	// func init():
	// 0:                                                                entry P:0 S:2
	// 	t0 = *init$guard                                                   bool
	// 	if t0 goto 2 else 1
	// 1:                                                    init.start P:1 S:1 idom:0
	// 	*init$guard = true:bool
	// 	t1 = fmt.init()                                                      ()
	// 	jump 2
	// 2:                                                     init.done P:2 S:0 idom:0
	// 	return
	//
	// # Name: hello.main
	// # Package: hello
	// # Location: hello.go:8:6
	// func main():
	// 0:                                                                entry P:0 S:0
	// 	t0 = new [1]any (varargs)                                       *[1]any
	// 	t1 = &t0[0:int]                                                    *any
	// 	t2 = make any <- string ("Hello, World!":string)                    any
	// 	*t1 = t2
	// 	t3 = slice t0[:]                                                  []any
	// 	t4 = fmt.Println(t3...)                              (n int, err error)
	// 	return
}

// This example builds SSA code for a set of packages using the
// [golang.org/x/tools/go/packages] API. This is what you would typically use for a
// analysis capable of operating on a single package.
func Example_loadPackages() {
	// Load, parse, and type-check the initial packages.
	cfg := &packages.Config{Mode: packages.LoadSyntax}
	initial, err := packages.Load(cfg, "fmt", "net/http")
	if err != nil {
		log.Fatal(err)
	}

	// Stop if any package had errors.
	// This step is optional; without it, the next step
	// will create SSA for only a subset of packages.
	if packages.PrintErrors(initial) > 0 {
		log.Fatalf("packages contain errors")
	}

	// Create SSA packages for all well-typed packages.
	prog, pkgs := ssautil.Packages(initial, ssa.PrintPackages)
	_ = prog

	// Build SSA code for the well-typed initial packages.
	for _, p := range pkgs {
		if p != nil {
			p.Build()
		}
	}
}

// This example builds SSA code for a set of packages plus all their dependencies,
// using the [golang.org/x/tools/go/packages] API.
// This is what you'd typically use for a whole-program analysis.
func Example_loadWholeProgram() {
	// Load, parse, and type-check the whole program.
	cfg := packages.Config{Mode: packages.LoadAllSyntax}
	initial, err := packages.Load(&cfg, "fmt", "net/http")
	if err != nil {
		log.Fatal(err)
	}

	// Create SSA packages for well-typed packages and their dependencies.
	prog, pkgs := ssautil.AllPackages(initial, ssa.PrintPackages|ssa.InstantiateGenerics)
	_ = pkgs

	// Build SSA code for the whole program.
	prog.Build()
}


================================================
FILE: go/ssa/func.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file implements the Function type.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"io"
	"iter"
	"os"
	"strings"

	"golang.org/x/tools/internal/typeparams"
)

// Like ObjectOf, but panics instead of returning nil.
// Only valid during f's create and build phases.
func (f *Function) objectOf(id *ast.Ident) types.Object {
	if o := f.info.ObjectOf(id); o != nil {
		return o
	}
	panic(fmt.Sprintf("no types.Object for ast.Ident %s @ %s",
		id.Name, f.Prog.Fset.Position(id.Pos())))
}

// Like TypeOf, but panics instead of returning nil.
// Only valid during f's create and build phases.
func (f *Function) typeOf(e ast.Expr) types.Type {
	if T := f.info.TypeOf(e); T != nil {
		return f.typ(T)
	}
	panic(fmt.Sprintf("no type for %T @ %s", e, f.Prog.Fset.Position(e.Pos())))
}

// typ is the locally instantiated type of T.
// If f is not an instantiation, then f.typ(T)==T.
func (f *Function) typ(T types.Type) types.Type {
	return f.subst.typ(T)
}

// If id is an Instance, returns info.Instances[id].Type.
// Otherwise returns f.typeOf(id).
func (f *Function) instanceType(id *ast.Ident) types.Type {
	if t, ok := f.info.Instances[id]; ok {
		return t.Type
	}
	return f.typeOf(id)
}

// selection returns a *selection corresponding to f.info.Selections[selector]
// with potential updates for type substitution.
func (f *Function) selection(selector *ast.SelectorExpr) *selection {
	sel := f.info.Selections[selector]
	if sel == nil {
		return nil
	}

	switch sel.Kind() {
	case types.MethodExpr, types.MethodVal:
		if recv := f.typ(sel.Recv()); recv != sel.Recv() {
			// recv changed during type substitution.
			pkg := f.declaredPackage().Pkg
			obj, index, indirect := types.LookupFieldOrMethod(recv, true, pkg, sel.Obj().Name())

			// sig replaces sel.Type(). See (types.Selection).Typ() for details.
			sig := obj.Type().(*types.Signature)
			sig = changeRecv(sig, newVar(sig.Recv().Name(), recv))
			if sel.Kind() == types.MethodExpr {
				sig = recvAsFirstArg(sig)
			}
			return &selection{
				kind:     sel.Kind(),
				recv:     recv,
				typ:      sig,
				obj:      obj,
				index:    index,
				indirect: indirect,
			}
		}
	}
	return toSelection(sel)
}

// Destinations associated with unlabelled for/switch/select stmts.
// We push/pop one of these as we enter/leave each construct and for
// each BranchStmt we scan for the innermost target of the right type.
type targets struct {
	tail         *targets // rest of stack
	_break       *BasicBlock
	_continue    *BasicBlock
	_fallthrough *BasicBlock
}

// Destinations associated with a labelled block.
// We populate these as labels are encountered in forward gotos or
// labelled statements.
// Forward gotos are resolved once it is known which statement they
// are associated with inside the Function.
type lblock struct {
	label     *types.Label // Label targeted by the blocks.
	resolved  bool         // _goto block encountered (back jump or resolved fwd jump)
	_goto     *BasicBlock
	_break    *BasicBlock
	_continue *BasicBlock
}

// label returns the symbol denoted by a label identifier.
//
// label should be a non-blank identifier (label.Name != "_").
func (f *Function) label(label *ast.Ident) *types.Label {
	return f.objectOf(label).(*types.Label)
}

// lblockOf returns the branch target associated with the
// specified label, creating it if needed.
func (f *Function) lblockOf(label *types.Label) *lblock {
	lb := f.lblocks[label]
	if lb == nil {
		lb = &lblock{
			label: label,
			_goto: f.newBasicBlock(label.Name()),
		}
		if f.lblocks == nil {
			f.lblocks = make(map[*types.Label]*lblock)
		}
		f.lblocks[label] = lb
	}
	return lb
}

// labelledBlock searches f for the block of the specified label.
//
// If f is a yield function, it additionally searches ancestor Functions
// corresponding to enclosing range-over-func statements within the
// same source function, so the returned block may belong to a different Function.
func labelledBlock(f *Function, label *types.Label, tok token.Token) *BasicBlock {
	if lb := f.lblocks[label]; lb != nil {
		var block *BasicBlock
		switch tok {
		case token.BREAK:
			block = lb._break
		case token.CONTINUE:
			block = lb._continue
		case token.GOTO:
			block = lb._goto
		}
		if block != nil {
			return block
		}
	}
	// Search ancestors if this is a yield function.
	if f.jump != nil {
		return labelledBlock(f.parent, label, tok)
	}
	return nil
}

// targetedBlock looks for the nearest block in f.targets
// (and f's ancestors) that matches tok's type, and returns
// the block and function it was found in.
func targetedBlock(f *Function, tok token.Token) *BasicBlock {
	if f == nil {
		return nil
	}
	for t := f.targets; t != nil; t = t.tail {
		var block *BasicBlock
		switch tok {
		case token.BREAK:
			block = t._break
		case token.CONTINUE:
			block = t._continue
		case token.FALLTHROUGH:
			block = t._fallthrough
		}
		if block != nil {
			return block
		}
	}
	// Search f's ancestors (in case f is a yield function).
	return targetedBlock(f.parent, tok)
}

// instrs returns an iterator that returns each reachable instruction of the SSA function.
func (f *Function) instrs() iter.Seq[Instruction] {
	return func(yield func(i Instruction) bool) {
		for _, block := range f.Blocks {
			for _, instr := range block.Instrs {
				if !yield(instr) {
					return
				}
			}
		}
	}
}

// addResultVar adds a result for a variable v to f.results and v to f.returnVars.
func (f *Function) addResultVar(v *types.Var) {
	result := emitLocalVar(f, v)
	f.results = append(f.results, result)
	f.returnVars = append(f.returnVars, v)
}

// addParamVar adds a parameter to f.Params.
func (f *Function) addParamVar(v *types.Var) *Parameter {
	name := v.Name()
	if name == "" {
		name = fmt.Sprintf("arg%d", len(f.Params))
	}
	param := &Parameter{
		name:   name,
		object: v,
		typ:    f.typ(v.Type()),
		parent: f,
	}
	f.Params = append(f.Params, param)
	return param
}

// addSpilledParam declares a parameter that is pre-spilled to the
// stack; the function body will load/store the spilled location.
// Subsequent lifting will eliminate spills where possible.
func (f *Function) addSpilledParam(obj *types.Var) {
	param := f.addParamVar(obj)
	spill := emitLocalVar(f, obj)
	f.emit(&Store{Addr: spill, Val: param})
}

// startBody initializes the function prior to generating SSA code for its body.
// Precondition: f.Type() already set.
func (f *Function) startBody() {
	f.currentBlock = f.newBasicBlock("entry")
	f.vars = make(map[*types.Var]Value) // needed for some synthetics, e.g. init
}

// createSyntacticParams populates f.Params and generates code (spills
// and named result locals) for all the parameters declared in the
// syntax.  In addition it populates the f.objects mapping.
//
// Preconditions:
// f.startBody() was called. f.info != nil.
// Postcondition:
// len(f.Params) == len(f.Signature.Params) + (f.Signature.Recv() ? 1 : 0)
func (f *Function) createSyntacticParams(recv *ast.FieldList, functype *ast.FuncType) {
	// Receiver (at most one inner iteration).
	if recv != nil {
		for _, field := range recv.List {
			for _, n := range field.Names {
				f.addSpilledParam(identVar(f, n))
			}
			// Anonymous receiver?  No need to spill.
			if field.Names == nil {
				f.addParamVar(f.Signature.Recv())
			}
		}
	}

	// Parameters.
	if functype.Params != nil {
		n := len(f.Params) // 1 if has recv, 0 otherwise
		for _, field := range functype.Params.List {
			for _, n := range field.Names {
				f.addSpilledParam(identVar(f, n))
			}
			// Anonymous parameter?  No need to spill.
			if field.Names == nil {
				f.addParamVar(f.Signature.Params().At(len(f.Params) - n))
			}
		}
	}

	// Results.
	if functype.Results != nil {
		for _, field := range functype.Results.List {
			// Implicit "var" decl of locals for named results.
			for _, n := range field.Names {
				v := identVar(f, n)
				f.addResultVar(v)
			}
			// Implicit "var" decl of local for an unnamed result.
			if field.Names == nil {
				v := f.Signature.Results().At(len(f.results))
				f.addResultVar(v)
			}
		}
	}
}

// createDeferStack initializes fn.deferstack to local variable
// initialized to a ssa:deferstack() call.
func (fn *Function) createDeferStack() {
	// Each syntactic function makes a call to ssa:deferstack,
	// which is spilled to a local. Unused ones are later removed.
	fn.deferstack = newVar("defer$stack", tDeferStack)
	call := &Call{Call: CallCommon{Value: vDeferStack}}
	call.setType(tDeferStack)
	deferstack := fn.emit(call)
	spill := emitLocalVar(fn, fn.deferstack)
	emitStore(fn, spill, deferstack, token.NoPos)
}

type setNumable interface {
	setNum(int)
}

// numberRegisters assigns numbers to all SSA registers
// (value-defining Instructions) in f, to aid debugging.
// (Non-Instruction Values are named at construction.)
func numberRegisters(f *Function) {
	v := 0
	for _, b := range f.Blocks {
		for _, instr := range b.Instrs {
			switch instr.(type) {
			case Value:
				instr.(setNumable).setNum(v)
				v++
			}
		}
	}
}

// buildReferrers populates the def/use information in all non-nil
// Value.Referrers slice.
// Precondition: all such slices are initially empty.
func buildReferrers(f *Function) {
	var rands []*Value
	for _, b := range f.Blocks {
		for _, instr := range b.Instrs {
			rands = instr.Operands(rands[:0]) // recycle storage
			for _, rand := range rands {
				if r := *rand; r != nil {
					if ref := r.Referrers(); ref != nil {
						*ref = append(*ref, instr)
					}
				}
			}
		}
	}
}

// finishBody() finalizes the contents of the function after SSA code generation of its body.
//
// The function is not done being built until done() is called.
func (f *Function) finishBody() {
	f.currentBlock = nil
	f.lblocks = nil
	f.returnVars = nil
	f.jump = nil
	f.source = nil
	f.exits = nil

	// Remove from f.Locals any Allocs that escape to the heap.
	j := 0
	for _, l := range f.Locals {
		if !l.Heap {
			f.Locals[j] = l
			j++
		}
	}
	// Nil out f.Locals[j:] to aid GC.
	for i := j; i < len(f.Locals); i++ {
		f.Locals[i] = nil
	}
	f.Locals = f.Locals[:j]

	optimizeBlocks(f)

	buildReferrers(f)

	buildDomTree(f)

	if f.Prog.mode&NaiveForm == 0 {
		// For debugging pre-state of lifting pass:
		// numberRegisters(f)
		// f.WriteTo(os.Stderr)
		lift(f)
	}

	// clear remaining builder state
	f.results = nil    // (used by lifting)
	f.deferstack = nil // (used by lifting)
	f.vars = nil       // (used by lifting)

	// clear out other function state (keep consistent with buildParamsOnly)
	f.subst = nil

	numberRegisters(f) // uses f.namedRegisters
}

// done marks the building of f's SSA body complete,
// along with any nested functions, and optionally prints them.
func (f *Function) done() {
	assert(f.parent == nil, "done called on an anonymous function")

	var visit func(*Function)
	visit = func(f *Function) {
		for _, anon := range f.AnonFuncs {
			visit(anon) // anon is done building before f.
		}

		f.uniq = 0    // done with uniq
		f.build = nil // function is built

		if f.Prog.mode&PrintFunctions != 0 {
			printMu.Lock()
			f.WriteTo(os.Stdout)
			printMu.Unlock()
		}

		if f.Prog.mode&SanityCheckFunctions != 0 {
			mustSanityCheck(f, nil)
		}
	}
	visit(f)
}

// removeNilBlocks eliminates nils from f.Blocks and updates each
// BasicBlock.Index.  Use this after any pass that may delete blocks.
func (f *Function) removeNilBlocks() {
	j := 0
	for _, b := range f.Blocks {
		if b != nil {
			b.Index = j
			f.Blocks[j] = b
			j++
		}
	}
	// Nil out f.Blocks[j:] to aid GC.
	for i := j; i < len(f.Blocks); i++ {
		f.Blocks[i] = nil
	}
	f.Blocks = f.Blocks[:j]
}

// SetDebugMode sets the debug mode for package pkg.  If true, all its
// functions will include full debug info.  This greatly increases the
// size of the instruction stream, and causes Functions to depend upon
// the ASTs, potentially keeping them live in memory for longer.
func (pkg *Package) SetDebugMode(debug bool) {
	pkg.debug = debug
}

// debugInfo reports whether debug info is wanted for this function.
func (f *Function) debugInfo() bool {
	// debug info for instantiations follows the debug info of their origin.
	p := f.declaredPackage()
	return p != nil && p.debug
}

// lookup returns the address of the named variable identified by obj
// that is local to function f or one of its enclosing functions.
// If escaping, the reference comes from a potentially escaping pointer
// expression and the referent must be heap-allocated.
// We assume the referent is a *Alloc or *Phi.
// (The only Phis at this stage are those created directly by go1.22 "for" loops.)
func (f *Function) lookup(obj *types.Var, escaping bool) Value {
	if v, ok := f.vars[obj]; ok {
		if escaping {
			switch v := v.(type) {
			case *Alloc:
				v.Heap = true
			case *Phi:
				for _, edge := range v.Edges {
					if alloc, ok := edge.(*Alloc); ok {
						alloc.Heap = true
					}
				}
			}
		}
		return v // function-local var (address)
	}

	// Definition must be in an enclosing function;
	// plumb it through intervening closures.
	if f.parent == nil {
		panic("no ssa.Value for " + obj.String())
	}
	outer := f.parent.lookup(obj, true) // escaping
	v := &FreeVar{
		name:   obj.Name(),
		typ:    outer.Type(),
		pos:    outer.Pos(),
		outer:  outer,
		parent: f,
	}
	f.vars[obj] = v
	f.FreeVars = append(f.FreeVars, v)
	return v
}

// emit emits the specified instruction to function f.
func (f *Function) emit(instr Instruction) Value {
	return f.currentBlock.emit(instr)
}

// RelString returns the full name of this function, qualified by
// package name, receiver type, etc.
//
// The specific formatting rules are not guaranteed and may change.
//
// Examples:
//
//	"math.IsNaN"                  // a package-level function
//	"(*bytes.Buffer).Bytes"       // a declared method or a wrapper
//	"(*bytes.Buffer).Bytes$thunk" // thunk (func wrapping method; receiver is param 0)
//	"(*bytes.Buffer).Bytes$bound" // bound (func wrapping method; receiver supplied by closure)
//	"main.main$1"                 // an anonymous function in main
//	"main.init#1"                 // a declared init function
//	"main.init"                   // the synthesized package initializer
//
// When these functions are referred to from within the same package
// (i.e. from == f.Pkg.Object), they are rendered without the package path.
// For example: "IsNaN", "(*Buffer).Bytes", etc.
//
// All non-synthetic functions have distinct package-qualified names.
// (But two methods may have the same name "(T).f" if one is a synthetic
// wrapper promoting a non-exported method "f" from another package; in
// that case, the strings are equal but the identifiers "f" are distinct.)
func (f *Function) RelString(from *types.Package) string {
	// Anonymous?
	if f.parent != nil {
		// An anonymous function's Name() looks like "parentName$1",
		// but its String() should include the type/package/etc.
		parent := f.parent.RelString(from)
		for i, anon := range f.parent.AnonFuncs {
			if anon == f {
				return fmt.Sprintf("%s$%d", parent, 1+i)
			}
		}

		return f.name // should never happen
	}

	// Method (declared or wrapper)?
	if recv := f.Signature.Recv(); recv != nil {
		return f.relMethod(from, recv.Type())
	}

	// Thunk?
	if f.method != nil {
		return f.relMethod(from, f.method.recv)
	}

	// Bound?
	if len(f.FreeVars) == 1 && strings.HasSuffix(f.name, "$bound") {
		return f.relMethod(from, f.FreeVars[0].Type())
	}

	// Package-level function?
	// Prefix with package name for cross-package references only.
	if p := f.relPkg(); p != nil && p != from {
		return fmt.Sprintf("%s.%s", p.Path(), f.name)
	}

	// Unknown.
	return f.name
}

func (f *Function) relMethod(from *types.Package, recv types.Type) string {
	return fmt.Sprintf("(%s).%s", relType(recv, from), f.name)
}

// writeSignature writes to buf the signature sig in declaration syntax.
func writeSignature(buf *bytes.Buffer, from *types.Package, name string, sig *types.Signature) {
	buf.WriteString("func ")
	if recv := sig.Recv(); recv != nil {
		buf.WriteString("(")
		if name := recv.Name(); name != "" {
			buf.WriteString(name)
			buf.WriteString(" ")
		}
		types.WriteType(buf, recv.Type(), types.RelativeTo(from))
		buf.WriteString(") ")
	}
	buf.WriteString(name)
	types.WriteSignature(buf, sig, types.RelativeTo(from))
}

// declaredPackage returns the package fn is declared in or nil if the
// function is not declared in a package.
func (fn *Function) declaredPackage() *Package {
	switch {
	case fn.Pkg != nil:
		return fn.Pkg // non-generic function  (does that follow??)
	case fn.topLevelOrigin != nil:
		return fn.topLevelOrigin.Pkg // instance of a named generic function
	case fn.parent != nil:
		return fn.parent.declaredPackage() // instance of an anonymous [generic] function
	default:
		return nil // function is not declared in a package, e.g. a wrapper.
	}
}

// relPkg returns types.Package fn is printed in relationship to.
func (fn *Function) relPkg() *types.Package {
	if p := fn.declaredPackage(); p != nil {
		return p.Pkg
	}
	return nil
}

var _ io.WriterTo = (*Function)(nil) // *Function implements io.Writer

func (f *Function) WriteTo(w io.Writer) (int64, error) {
	var buf bytes.Buffer
	WriteFunction(&buf, f)
	n, err := w.Write(buf.Bytes())
	return int64(n), err
}

// WriteFunction writes to buf a human-readable "disassembly" of f.
func WriteFunction(buf *bytes.Buffer, f *Function) {
	fmt.Fprintf(buf, "# Name: %s\n", f.String())
	if f.Pkg != nil {
		fmt.Fprintf(buf, "# Package: %s\n", f.Pkg.Pkg.Path())
	}
	if syn := f.Synthetic; syn != "" {
		fmt.Fprintln(buf, "# Synthetic:", syn)
	}
	if pos := f.Pos(); pos.IsValid() {
		fmt.Fprintf(buf, "# Location: %s\n", f.Prog.Fset.Position(pos))
	}

	if f.parent != nil {
		fmt.Fprintf(buf, "# Parent: %s\n", f.parent.Name())
	}

	if f.Recover != nil {
		fmt.Fprintf(buf, "# Recover: %s\n", f.Recover)
	}

	from := f.relPkg()

	if f.FreeVars != nil {
		buf.WriteString("# Free variables:\n")
		for i, fv := range f.FreeVars {
			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, fv.Name(), relType(fv.Type(), from))
		}
	}

	if len(f.Locals) > 0 {
		buf.WriteString("# Locals:\n")
		for i, l := range f.Locals {
			fmt.Fprintf(buf, "# % 3d:\t%s %s\n", i, l.Name(), relType(typeparams.MustDeref(l.Type()), from))
		}
	}
	writeSignature(buf, from, f.Name(), f.Signature)
	buf.WriteString(":\n")

	if f.Blocks == nil {
		buf.WriteString("\t(external)\n")
	}

	// NB. column calculations are confused by non-ASCII
	// characters and assume 8-space tabs.
	const punchcard = 80 // for old time's sake.
	const tabwidth = 8
	for _, b := range f.Blocks {
		if b == nil {
			// Corrupt CFG.
			fmt.Fprintf(buf, ".nil:\n")
			continue
		}
		n, _ := fmt.Fprintf(buf, "%d:", b.Index)
		// (|predecessors|, |successors|, immediate dominator)
		bmsg := fmt.Sprintf("%s P:%d S:%d", b.Comment, len(b.Preds), len(b.Succs))
		if b.Idom() != nil {
			bmsg = fmt.Sprintf("%s idom:%d", bmsg, b.Idom().Index)
		}
		fmt.Fprintf(buf, "%*s%s\n", punchcard-1-n-len(bmsg), "", bmsg)

		if false { // CFG debugging
			fmt.Fprintf(buf, "\t# CFG: %s --> %s --> %s\n", b.Preds, b, b.Succs)
		}
		for _, instr := range b.Instrs {
			buf.WriteString("\t")
			switch v := instr.(type) {
			case Value:
				l := punchcard - tabwidth
				// Left-align the instruction.
				if name := v.Name(); name != "" {
					n, _ := fmt.Fprintf(buf, "%s = ", name)
					l -= n
				}
				n, _ := buf.WriteString(instr.String())
				l -= n
				// Right-align the type if there's space.
				if t := v.Type(); t != nil {
					buf.WriteByte(' ')
					ts := relType(t, from)
					l -= len(ts) + len("  ") // (spaces before and after type)
					if l > 0 {
						fmt.Fprintf(buf, "%*s", l, "")
					}
					buf.WriteString(ts)
				}
			case nil:
				// Be robust against bad transforms.
				buf.WriteString("<deleted>")
			default:
				buf.WriteString(instr.String())
			}
			// -mode=S: show line numbers
			if f.Prog.mode&LogSource != 0 {
				if pos := instr.Pos(); pos.IsValid() {
					fmt.Fprintf(buf, " L%d", f.Prog.Fset.Position(pos).Line)
				}
			}
			buf.WriteString("\n")
		}
	}
	fmt.Fprintf(buf, "\n")
}

// newBasicBlock adds to f a new basic block and returns it.  It does
// not automatically become the current block for subsequent calls to emit.
// comment is an optional string for more readable debugging output.
func (f *Function) newBasicBlock(comment string) *BasicBlock {
	b := &BasicBlock{
		Index:   len(f.Blocks),
		Comment: comment,
		parent:  f,
	}
	b.Succs = b.succs2[:0]
	f.Blocks = append(f.Blocks, b)
	return b
}

// NewFunction returns a new synthetic Function instance belonging to
// prog, with its name and signature fields set as specified.
//
// The caller is responsible for initializing the remaining fields of
// the function object, e.g. Pkg, Params, Blocks.
//
// It is practically impossible for clients to construct well-formed
// SSA functions/packages/programs directly, so we assume this is the
// job of the Builder alone.  NewFunction exists to provide clients a
// little flexibility.  For example, analysis tools may wish to
// construct fake Functions for the root of the callgraph, a fake
// "reflect" package, etc.
//
// TODO(adonovan): think harder about the API here.
func (prog *Program) NewFunction(name string, sig *types.Signature, provenance string) *Function {
	return &Function{Prog: prog, name: name, Signature: sig, Synthetic: provenance}
}

// Syntax returns the function's syntax (*ast.Func{Decl,Lit})
// if it was produced from syntax or an *ast.RangeStmt if
// it is a range-over-func yield function.
func (f *Function) Syntax() ast.Node { return f.syntax }

// identVar returns the variable defined by id.
func identVar(fn *Function, id *ast.Ident) *types.Var {
	return fn.info.Defs[id].(*types.Var)
}

// unique returns a unique positive int within the source tree of f.
// The source tree of f includes all of f's ancestors by parent and all
// of the AnonFuncs contained within these.
func unique(f *Function) int64 {
	f.uniq++
	return f.uniq
}

// exit is a change of control flow going from a range-over-func
// yield function to an ancestor function caused by a break, continue,
// goto, or return statement.
//
// There are 3 types of exits:
// * return from the source function (from ReturnStmt),
// * jump to a block (from break and continue statements [labelled/unlabelled]),
// * go to a label (from goto statements).
//
// As the builder does one pass over the ast, it is unclear whether
// a forward goto statement will leave a range-over-func body.
// The function being exited to is unresolved until the end
// of building the range-over-func body.
type exit struct {
	id   int64     // unique value for exit within from and to
	from *Function // the function the exit starts from
	to   *Function // the function being exited to (nil if unresolved)
	pos  token.Pos

	block *BasicBlock  // basic block within to being jumped to.
	label *types.Label // forward label being jumped to via goto.
	// block == nil && label == nil => return
}

// storeVar emits to function f code to store a value v to a *types.Var x.
func storeVar(f *Function, x *types.Var, v Value, pos token.Pos) {
	emitStore(f, f.lookup(x, true), v, pos)
}

// labelExit creates a new exit to a yield fn to exit the function using a label.
func labelExit(fn *Function, label *types.Label, pos token.Pos) *exit {
	e := &exit{
		id:    unique(fn),
		from:  fn,
		to:    nil,
		pos:   pos,
		label: label,
	}
	fn.exits = append(fn.exits, e)
	return e
}

// blockExit creates a new exit to a yield fn that jumps to a basic block.
func blockExit(fn *Function, block *BasicBlock, pos token.Pos) *exit {
	e := &exit{
		id:    unique(fn),
		from:  fn,
		to:    block.parent,
		pos:   pos,
		block: block,
	}
	fn.exits = append(fn.exits, e)
	return e
}

// returnExit creates a new exit to a yield fn that returns the source function.
func returnExit(fn *Function, pos token.Pos) *exit {
	e := &exit{
		id:   unique(fn),
		from: fn,
		to:   fn.source,
		pos:  pos,
	}
	fn.exits = append(fn.exits, e)
	return e
}


================================================
FILE: go/ssa/instantiate.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"fmt"
	"go/types"
	"slices"
	"sync"
)

// A generic records information about a generic origin function,
// including a cache of existing instantiations.
type generic struct {
	instancesMu sync.Mutex
	instances   map[*typeList]*Function // canonical type arguments to an instance.
}

// instance returns a Function that is the instantiation of generic
// origin function fn with the type arguments targs.
//
// Any created instance is added to cr.
//
// Acquires fn.generic.instancesMu.
func (fn *Function) instance(targs []types.Type, b *builder) *Function {
	key := fn.Prog.canon.List(targs)

	gen := fn.generic

	gen.instancesMu.Lock()
	defer gen.instancesMu.Unlock()
	inst, ok := gen.instances[key]
	if !ok {
		inst = createInstance(fn, targs)
		inst.buildshared = b.shared()
		b.enqueue(inst)

		if gen.instances == nil {
			gen.instances = make(map[*typeList]*Function)
		}
		gen.instances[key] = inst
	} else {
		b.waitForSharedFunction(inst)
	}
	return inst
}

// createInstance returns the instantiation of generic function fn using targs.
//
// Requires fn.generic.instancesMu.
func createInstance(fn *Function, targs []types.Type) *Function {
	prog := fn.Prog

	// Compute signature.
	var sig *types.Signature
	var obj *types.Func
	if recv := fn.Signature.Recv(); recv != nil {
		// method
		obj = prog.canon.instantiateMethod(fn.object, targs, prog.ctxt)
		sig = obj.Type().(*types.Signature)
	} else {
		// function
		instSig, err := types.Instantiate(prog.ctxt, fn.Signature, targs, false)
		if err != nil {
			panic(err)
		}
		instance, ok := instSig.(*types.Signature)
		if !ok {
			panic("Instantiate of a Signature returned a non-signature")
		}
		obj = fn.object // instantiation does not exist yet
		sig = prog.canon.Type(instance).(*types.Signature)
	}

	// Choose strategy (instance or wrapper).
	var (
		synthetic string
		subst     *subster
		build     buildFunc
	)
	if prog.mode&InstantiateGenerics != 0 && !prog.isParameterized(targs...) {
		synthetic = fmt.Sprintf("instance of %s", fn.Name())
		if fn.syntax != nil {
			subst = makeSubster(prog.ctxt, obj, fn.typeparams, targs)
			build = (*builder).buildFromSyntax
		} else {
			build = (*builder).buildParamsOnly
		}
	} else {
		synthetic = fmt.Sprintf("instantiation wrapper of %s", fn.Name())
		build = (*builder).buildInstantiationWrapper
	}

	/* generic instance or instantiation wrapper */
	return &Function{
		name:           fmt.Sprintf("%s%s", fn.Name(), targs), // may not be unique
		object:         obj,
		Signature:      sig,
		Synthetic:      synthetic,
		syntax:         fn.syntax,    // \
		info:           fn.info,      //  } empty for non-created packages
		goversion:      fn.goversion, // /
		build:          build,
		topLevelOrigin: fn,
		pos:            obj.Pos(),
		Pkg:            nil,
		Prog:           fn.Prog,
		typeparams:     fn.typeparams, // share with origin
		typeargs:       targs,
		subst:          subst,
	}
}

// isParameterized reports whether any of the specified types contains
// a free type parameter. It is safe to call concurrently.
func (prog *Program) isParameterized(ts ...types.Type) bool {
	prog.hasParamsMu.Lock()
	defer prog.hasParamsMu.Unlock()

	// TODO(adonovan): profile. If this operation is expensive,
	// handle the most common but shallow cases such as T, pkg.T,
	// *T without consulting the cache under the lock.

	return slices.ContainsFunc(ts, prog.hasParams.Has)
}


================================================
FILE: go/ssa/instantiate_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"fmt"
	"go/types"
	"reflect"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

// TestNeedsInstance ensures that new method instances can be created via MethodValue.
func TestNeedsInstance(t *testing.T) {
	const input = `
package p

import "unsafe"

type Pointer[T any] struct {
	v unsafe.Pointer
}

func (x *Pointer[T]) Load() *T {
	return (*T)(LoadPointer(&x.v))
}

func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)
`
	// The SSA members for this package should look something like this:
	//      func  LoadPointer func(addr *unsafe.Pointer) (val unsafe.Pointer)
	//      type  Pointer     struct{v unsafe.Pointer}
	//        method (*Pointer[T any]) Load() *T
	//      func  init        func()
	//      var   init$guard  bool

	for _, mode := range []ssa.BuilderMode{
		ssa.SanityCheckFunctions,
		ssa.SanityCheckFunctions | ssa.InstantiateGenerics,
	} {
		p, _ := buildPackage(t, input, mode)
		prog := p.Prog

		ptr := p.Type("Pointer").Type().(*types.Named)
		if ptr.NumMethods() != 1 {
			t.Fatalf("Expected Pointer to have 1 method. got %d", ptr.NumMethods())
		}

		obj := ptr.Method(0)
		if obj.Name() != "Load" {
			t.Errorf("Expected Pointer to have method named 'Load'. got %q", obj.Name())
		}

		meth := prog.FuncValue(obj)

		// instantiateLoadMethod returns the first method (Load) of the instantiation *Pointer[T].
		instantiateLoadMethod := func(T types.Type) *ssa.Function {
			ptrT, err := types.Instantiate(nil, ptr, []types.Type{T}, false)
			if err != nil {
				t.Fatalf("Failed to Instantiate %q by %q", ptr, T)
			}
			methods := types.NewMethodSet(types.NewPointer(ptrT))
			if methods.Len() != 1 {
				t.Fatalf("Expected 1 method for %q. got %d", ptrT, methods.Len())
			}
			return prog.MethodValue(methods.At(0))
		}

		intSliceTyp := types.NewSlice(types.Typ[types.Int])
		instance := instantiateLoadMethod(intSliceTyp) // (*Pointer[[]int]).Load
		if instance.Origin() != meth {
			t.Errorf("Expected Origin of %s to be %s. got %s", instance, meth, instance.Origin())
		}
		if len(instance.TypeArgs()) != 1 || !types.Identical(instance.TypeArgs()[0], intSliceTyp) {
			t.Errorf("Expected TypeArgs of %s to be %v. got %v", instance, []types.Type{intSliceTyp}, instance.TypeArgs())
		}

		// A second request with an identical type returns the same Function.
		second := instantiateLoadMethod(types.NewSlice(types.Typ[types.Int]))
		if second != instance {
			t.Error("Expected second identical instantiation to be the same function")
		}

		// (*Pointer[[]uint]).Load
		inst2 := instantiateLoadMethod(types.NewSlice(types.Typ[types.Uint]))

		if instance.Name() >= inst2.Name() {
			t.Errorf("Expected name of instance %s to be before instance %v", instance, inst2)
		}
	}
}

// TestCallsToInstances checks that calles of calls to generic functions,
// without monomorphization, are wrappers around the origin generic function.
func TestCallsToInstances(t *testing.T) {
	const input = `
package p

type I interface {
	Foo()
}

type A int
func (a A) Foo() {}

type J[T any] interface{ Bar() T }
type K[T any] struct{ J[T] }

func Id[T any] (t T) T {
	return t
}

func Lambda[T I]() func() func(T) {
	return func() func(T) {
		return T.Foo
	}
}

func NoOp[T any]() {}

func Bar[T interface { Foo(); ~int | ~string }, U any] (t T, u U) {
	Id[U](u)
	Id[T](t)
}

func Make[T any]() interface{} {
	NoOp[K[T]]()
	return nil
}

func entry(i int, a A) int {
	Lambda[A]()()(a)

	x := Make[int]()
	if j, ok := x.(interface{ Bar() int }); ok {
		print(j)
	}

	Bar[A, int](a, i)

	return Id[int](i)
}
`
	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)
	all := ssautil.AllFunctions(p.Prog)

	for _, ti := range []struct {
		orig         string
		instance     string
		tparams      string
		targs        string
		chTypeInstrs int // number of ChangeType instructions in f's body
	}{
		{"Id", "Id[int]", "[T]", "[int]", 2},
		{"Lambda", "Lambda[p.A]", "[T]", "[p.A]", 1},
		{"Make", "Make[int]", "[T]", "[int]", 0},
		{"NoOp", "NoOp[p.K[T]]", "[T]", "[p.K[T]]", 0},
	} {
		test := ti
		t.Run(test.instance, func(t *testing.T) {
			f := p.Members[test.orig].(*ssa.Function)
			if f == nil {
				t.Fatalf("origin function not found")
			}

			var i *ssa.Function
			for _, fn := range instancesOf(all, f) {
				if fn.Name() == test.instance {
					i = fn
					break
				}
			}
			if i == nil {
				t.Fatalf("instance not found")
			}

			// for logging on failures
			var body strings.Builder
			i.WriteTo(&body)
			t.Log(body.String())

			if len(i.Blocks) != 1 {
				t.Fatalf("body has more than 1 block")
			}

			if instrs := changeTypeInstrs(i.Blocks[0]); instrs != test.chTypeInstrs {
				t.Errorf("want %v instructions; got %v", test.chTypeInstrs, instrs)
			}

			if test.tparams != tparams(i) {
				t.Errorf("want %v type params; got %v", test.tparams, tparams(i))
			}

			if test.targs != targs(i) {
				t.Errorf("want %v type arguments; got %v", test.targs, targs(i))
			}
		})
	}
}

func tparams(f *ssa.Function) string {
	tplist := f.TypeParams()
	var tps []string
	for tparam := range tplist.TypeParams() {
		tps = append(tps, tparam.String())
	}
	return fmt.Sprint(tps)
}

func targs(f *ssa.Function) string {
	var tas []string
	for _, ta := range f.TypeArgs() {
		tas = append(tas, ta.String())
	}
	return fmt.Sprint(tas)
}

func changeTypeInstrs(b *ssa.BasicBlock) int {
	cnt := 0
	for _, i := range b.Instrs {
		if _, ok := i.(*ssa.ChangeType); ok {
			cnt++
		}
	}
	return cnt
}

func TestInstanceUniqueness(t *testing.T) {
	const input = `
package p

func H[T any](t T) {
	print(t)
}

func F[T any](t T) {
	H[T](t)
	H[T](t)
	H[T](t)
}

func G[T any](t T) {
	H[T](t)
	H[T](t)
}

func Foo[T any, S any](t T, s S) {
	Foo[S, T](s, t)
	Foo[T, S](t, s)
}
`
	p, _ := buildPackage(t, input, ssa.SanityCheckFunctions)

	all := ssautil.AllFunctions(p.Prog)
	for _, test := range []struct {
		orig      string
		instances string
	}{
		{"H", "[p.H[T] p.H[T]]"},
		{"Foo", "[p.Foo[S T] p.Foo[T S]]"},
	} {
		t.Run(test.orig, func(t *testing.T) {
			f := p.Members[test.orig].(*ssa.Function)
			if f == nil {
				t.Fatalf("origin function not found")
			}

			instances := instancesOf(all, f)
			sort.Slice(instances, func(i, j int) bool { return instances[i].Name() < instances[j].Name() })

			if got := fmt.Sprintf("%v", instances); !reflect.DeepEqual(got, test.instances) {
				t.Errorf("got %v instances, want %v", got, test.instances)
			}
		})
	}
}

// instancesOf returns a new unordered slice of all instances of the
// specified function g in fns.
func instancesOf(fns map[*ssa.Function]bool, g *ssa.Function) []*ssa.Function {
	var instances []*ssa.Function
	for fn := range fns {
		if fn != g && fn.Origin() == g {
			instances = append(instances, fn)
		}
	}
	return instances
}


================================================
FILE: go/ssa/interp/external.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp

// Emulated functions that we cannot interpret because they are
// external or because they use "unsafe" or "reflect" operations.

import (
	"bytes"
	"maps"
	"math"
	"os"
	"runtime"
	"slices"
	"sort"
	"strconv"
	"strings"
	"time"
	"unicode/utf8"
)

type externalFn func(fr *frame, args []value) value

// TODO(adonovan): fix: reflect.Value abstracts an lvalue or an
// rvalue; Set() causes mutations that can be observed via aliases.
// We have not captured that correctly here.

// Key strings are from Function.String().
var externals = make(map[string]externalFn)

func init() {
	// That little dot ۰ is an Arabic zero numeral (U+06F0), categories [Nd].
	maps.Copy(externals, map[string]externalFn{
		"(reflect.Value).Bool":            ext۰reflect۰Value۰Bool,
		"(reflect.Value).CanAddr":         ext۰reflect۰Value۰CanAddr,
		"(reflect.Value).CanInterface":    ext۰reflect۰Value۰CanInterface,
		"(reflect.Value).Elem":            ext۰reflect۰Value۰Elem,
		"(reflect.Value).Field":           ext۰reflect۰Value۰Field,
		"(reflect.Value).Float":           ext۰reflect۰Value۰Float,
		"(reflect.Value).Index":           ext۰reflect۰Value۰Index,
		"(reflect.Value).Int":             ext۰reflect۰Value۰Int,
		"(reflect.Value).Interface":       ext۰reflect۰Value۰Interface,
		"(reflect.Value).IsNil":           ext۰reflect۰Value۰IsNil,
		"(reflect.Value).IsValid":         ext۰reflect۰Value۰IsValid,
		"(reflect.Value).Kind":            ext۰reflect۰Value۰Kind,
		"(reflect.Value).Len":             ext۰reflect۰Value۰Len,
		"(reflect.Value).MapIndex":        ext۰reflect۰Value۰MapIndex,
		"(reflect.Value).MapKeys":         ext۰reflect۰Value۰MapKeys,
		"(reflect.Value).NumField":        ext۰reflect۰Value۰NumField,
		"(reflect.Value).NumMethod":       ext۰reflect۰Value۰NumMethod,
		"(reflect.Value).Pointer":         ext۰reflect۰Value۰Pointer,
		"(reflect.Value).Set":             ext۰reflect۰Value۰Set,
		"(reflect.Value).String":          ext۰reflect۰Value۰String,
		"(reflect.Value).Type":            ext۰reflect۰Value۰Type,
		"(reflect.Value).Uint":            ext۰reflect۰Value۰Uint,
		"(reflect.error).Error":           ext۰reflect۰error۰Error,
		"(reflect.rtype).Bits":            ext۰reflect۰rtype۰Bits,
		"(reflect.rtype).Elem":            ext۰reflect۰rtype۰Elem,
		"(reflect.rtype).Field":           ext۰reflect۰rtype۰Field,
		"(reflect.rtype).In":              ext۰reflect۰rtype۰In,
		"(reflect.rtype).Kind":            ext۰reflect۰rtype۰Kind,
		"(reflect.rtype).NumField":        ext۰reflect۰rtype۰NumField,
		"(reflect.rtype).NumIn":           ext۰reflect۰rtype۰NumIn,
		"(reflect.rtype).NumMethod":       ext۰reflect۰rtype۰NumMethod,
		"(reflect.rtype).NumOut":          ext۰reflect۰rtype۰NumOut,
		"(reflect.rtype).Out":             ext۰reflect۰rtype۰Out,
		"(reflect.rtype).Size":            ext۰reflect۰rtype۰Size,
		"(reflect.rtype).String":          ext۰reflect۰rtype۰String,
		"bytes.Equal":                     ext۰bytes۰Equal,
		"bytes.IndexByte":                 ext۰bytes۰IndexByte,
		"fmt.Sprint":                      ext۰fmt۰Sprint,
		"math.Abs":                        ext۰math۰Abs,
		"math.Copysign":                   ext۰math۰Copysign,
		"math.Exp":                        ext۰math۰Exp,
		"math.Float32bits":                ext۰math۰Float32bits,
		"math.Float32frombits":            ext۰math۰Float32frombits,
		"math.Float64bits":                ext۰math۰Float64bits,
		"math.Float64frombits":            ext۰math۰Float64frombits,
		"math.Inf":                        ext۰math۰Inf,
		"math.IsNaN":                      ext۰math۰IsNaN,
		"math.Ldexp":                      ext۰math۰Ldexp,
		"math.Log":                        ext۰math۰Log,
		"math.Min":                        ext۰math۰Min,
		"math.NaN":                        ext۰math۰NaN,
		"math.Sqrt":                       ext۰math۰Sqrt,
		"os.Exit":                         ext۰os۰Exit,
		"os.Getenv":                       ext۰os۰Getenv,
		"reflect.New":                     ext۰reflect۰New,
		"reflect.SliceOf":                 ext۰reflect۰SliceOf,
		"reflect.TypeOf":                  ext۰reflect۰TypeOf,
		"reflect.ValueOf":                 ext۰reflect۰ValueOf,
		"reflect.Zero":                    ext۰reflect۰Zero,
		"runtime.Breakpoint":              ext۰runtime۰Breakpoint,
		"runtime.GC":                      ext۰runtime۰GC,
		"runtime.GOMAXPROCS":              ext۰runtime۰GOMAXPROCS,
		"runtime.GOROOT":                  ext۰runtime۰GOROOT,
		"runtime.Goexit":                  ext۰runtime۰Goexit,
		"runtime.Gosched":                 ext۰runtime۰Gosched,
		"runtime.NumCPU":                  ext۰runtime۰NumCPU,
		"sort.Float64s":                   ext۰sort۰Float64s,
		"sort.Ints":                       ext۰sort۰Ints,
		"sort.Strings":                    ext۰sort۰Strings,
		"strconv.Atoi":                    ext۰strconv۰Atoi,
		"strconv.Itoa":                    ext۰strconv۰Itoa,
		"strconv.FormatFloat":             ext۰strconv۰FormatFloat,
		"strings.Count":                   ext۰strings۰Count,
		"strings.EqualFold":               ext۰strings۰EqualFold,
		"strings.Index":                   ext۰strings۰Index,
		"strings.IndexByte":               ext۰strings۰IndexByte,
		"strings.Replace":                 ext۰strings۰Replace,
		"strings.ToLower":                 ext۰strings۰ToLower,
		"time.Sleep":                      ext۰time۰Sleep,
		"unicode/utf8.DecodeRuneInString": ext۰unicode۰utf8۰DecodeRuneInString,
	})
}

func ext۰bytes۰Equal(fr *frame, args []value) value {
	// func Equal(a, b []byte) bool
	a := args[0].([]value)
	b := args[1].([]value)
	return slices.Equal(a, b)
}

func ext۰bytes۰IndexByte(fr *frame, args []value) value {
	// func IndexByte(s []byte, c byte) int
	s := args[0].([]value)
	c := args[1].(byte)
	for i, b := range s {
		if b.(byte) == c {
			return i
		}
	}
	return -1
}

func ext۰math۰Float64frombits(fr *frame, args []value) value {
	return math.Float64frombits(args[0].(uint64))
}

func ext۰math۰Float64bits(fr *frame, args []value) value {
	return math.Float64bits(args[0].(float64))
}

func ext۰math۰Float32frombits(fr *frame, args []value) value {
	return math.Float32frombits(args[0].(uint32))
}

func ext۰math۰Abs(fr *frame, args []value) value {
	return math.Abs(args[0].(float64))
}

func ext۰math۰Copysign(fr *frame, args []value) value {
	return math.Copysign(args[0].(float64), args[1].(float64))
}

func ext۰math۰Exp(fr *frame, args []value) value {
	return math.Exp(args[0].(float64))
}

func ext۰math۰Float32bits(fr *frame, args []value) value {
	return math.Float32bits(args[0].(float32))
}

func ext۰math۰Min(fr *frame, args []value) value {
	return math.Min(args[0].(float64), args[1].(float64))
}

func ext۰math۰NaN(fr *frame, args []value) value {
	return math.NaN()
}

func ext۰math۰IsNaN(fr *frame, args []value) value {
	return math.IsNaN(args[0].(float64))
}

func ext۰math۰Inf(fr *frame, args []value) value {
	return math.Inf(args[0].(int))
}

func ext۰math۰Ldexp(fr *frame, args []value) value {
	return math.Ldexp(args[0].(float64), args[1].(int))
}

func ext۰math۰Log(fr *frame, args []value) value {
	return math.Log(args[0].(float64))
}

func ext۰math۰Sqrt(fr *frame, args []value) value {
	return math.Sqrt(args[0].(float64))
}

func ext۰runtime۰Breakpoint(fr *frame, args []value) value {
	runtime.Breakpoint()
	return nil
}

func ext۰sort۰Ints(fr *frame, args []value) value {
	x := args[0].([]value)
	sort.Slice(x, func(i, j int) bool {
		return x[i].(int) < x[j].(int)
	})
	return nil
}
func ext۰sort۰Strings(fr *frame, args []value) value {
	x := args[0].([]value)
	sort.Slice(x, func(i, j int) bool {
		return x[i].(string) < x[j].(string)
	})
	return nil
}
func ext۰sort۰Float64s(fr *frame, args []value) value {
	x := args[0].([]value)
	sort.Slice(x, func(i, j int) bool {
		return x[i].(float64) < x[j].(float64)
	})
	return nil
}

func ext۰strconv۰Atoi(fr *frame, args []value) value {
	i, e := strconv.Atoi(args[0].(string))
	if e != nil {
		return tuple{i, iface{fr.i.runtimeErrorString, e.Error()}}
	}
	return tuple{i, iface{}}
}
func ext۰strconv۰Itoa(fr *frame, args []value) value {
	return strconv.Itoa(args[0].(int))
}
func ext۰strconv۰FormatFloat(fr *frame, args []value) value {
	return strconv.FormatFloat(args[0].(float64), args[1].(byte), args[2].(int), args[3].(int))
}

func ext۰strings۰Count(fr *frame, args []value) value {
	return strings.Count(args[0].(string), args[1].(string))
}

func ext۰strings۰EqualFold(fr *frame, args []value) value {
	return strings.EqualFold(args[0].(string), args[1].(string))
}
func ext۰strings۰IndexByte(fr *frame, args []value) value {
	return strings.IndexByte(args[0].(string), args[1].(byte))
}

func ext۰strings۰Index(fr *frame, args []value) value {
	return strings.Index(args[0].(string), args[1].(string))
}

func ext۰strings۰Replace(fr *frame, args []value) value {
	// func Replace(s, old, new string, n int) string
	s := args[0].(string)
	new := args[1].(string)
	old := args[2].(string)
	n := args[3].(int)
	return strings.Replace(s, old, new, n)
}

func ext۰strings۰ToLower(fr *frame, args []value) value {
	return strings.ToLower(args[0].(string))
}

func ext۰runtime۰GOMAXPROCS(fr *frame, args []value) value {
	// Ignore args[0]; don't let the interpreted program
	// set the interpreter's GOMAXPROCS!
	return runtime.GOMAXPROCS(0)
}

func ext۰runtime۰Goexit(fr *frame, args []value) value {
	// TODO(adonovan): don't kill the interpreter's main goroutine.
	runtime.Goexit()
	return nil
}

func ext۰runtime۰GOROOT(fr *frame, args []value) value {
	return runtime.GOROOT()
}

func ext۰runtime۰GC(fr *frame, args []value) value {
	runtime.GC()
	return nil
}

func ext۰runtime۰Gosched(fr *frame, args []value) value {
	runtime.Gosched()
	return nil
}

func ext۰runtime۰NumCPU(fr *frame, args []value) value {
	return runtime.NumCPU()
}

func ext۰time۰Sleep(fr *frame, args []value) value {
	time.Sleep(time.Duration(args[0].(int64)))
	return nil
}

func ext۰os۰Getenv(fr *frame, args []value) value {
	name := args[0].(string)
	switch name {
	case "GOSSAINTERP":
		return "1"
	}
	return os.Getenv(name)
}

func ext۰os۰Exit(fr *frame, args []value) value {
	panic(exitPanic(args[0].(int)))
}

func ext۰unicode۰utf8۰DecodeRuneInString(fr *frame, args []value) value {
	r, n := utf8.DecodeRuneInString(args[0].(string))
	return tuple{r, n}
}

// A fake function for turning an arbitrary value into a string.
// Handles only the cases needed by the tests.
// Uses same logic as 'print' built-in.
func ext۰fmt۰Sprint(fr *frame, args []value) value {
	buf := new(bytes.Buffer)
	wasStr := false
	for i, arg := range args[0].([]value) {
		x := arg.(iface).v
		_, isStr := x.(string)
		if i > 0 && !wasStr && !isStr {
			buf.WriteByte(' ')
		}
		wasStr = isStr
		buf.WriteString(toString(x))
	}
	return buf.String()
}


================================================
FILE: go/ssa/interp/interp.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package ssa/interp defines an interpreter for the SSA
// representation of Go programs.
//
// This interpreter is provided as an adjunct for testing the SSA
// construction algorithm.  Its purpose is to provide a minimal
// metacircular implementation of the dynamic semantics of each SSA
// instruction.  It is not, and will never be, a production-quality Go
// interpreter.
//
// The following is a partial list of Go features that are currently
// unsupported or incomplete in the interpreter.
//
// * Unsafe operations, including all uses of unsafe.Pointer, are
// impossible to support given the "boxed" value representation we
// have chosen.
//
// * The reflect package is only partially implemented.
//
// * The "testing" package is no longer supported because it
// depends on low-level details that change too often.
//
// * "sync/atomic" operations are not atomic due to the "boxed" value
// representation: it is not possible to read, modify and write an
// interface value atomically. As a consequence, Mutexes are currently
// broken.
//
// * recover is only partially implemented.  Also, the interpreter
// makes no attempt to distinguish target panics from interpreter
// crashes.
//
// * the sizes of the int, uint and uintptr types in the target
// program are assumed to be the same as those of the interpreter
// itself.
//
// * all values occupy space, even those of types defined by the spec
// to have zero size, e.g. struct{}.  This can cause asymptotic
// performance degradation.
//
// * os.Exit is implemented using panic, causing deferred functions to
// run.
package interp // import "golang.org/x/tools/go/ssa/interp"

import (
	"fmt"
	"go/token"
	"go/types"
	"log"
	"os"
	"reflect"
	"runtime"
	"slices"
	"sync/atomic"
	_ "unsafe"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/typeparams"
)

type continuation int

const (
	kNext continuation = iota
	kReturn
	kJump
)

// Mode is a bitmask of options affecting the interpreter.
type Mode uint

const (
	DisableRecover Mode = 1 << iota // Disable recover() in target programs; show interpreter crash instead.
	EnableTracing                   // Print a trace of all instructions as they are interpreted.
)

type methodSet map[string]*ssa.Function

// State shared between all interpreted goroutines.
type interpreter struct {
	osArgs             []value                // the value of os.Args
	prog               *ssa.Program           // the SSA program
	globals            map[*ssa.Global]*value // addresses of global variables (immutable)
	mode               Mode                   // interpreter options
	reflectPackage     *ssa.Package           // the fake reflect package
	errorMethods       methodSet              // the method set of reflect.error, which implements the error interface.
	rtypeMethods       methodSet              // the method set of rtype, which implements the reflect.Type interface.
	runtimeErrorString types.Type             // the runtime.errorString type
	sizes              types.Sizes            // the effective type-sizing function
	goroutines         int32                  // atomically updated
}

type deferred struct {
	fn    value
	args  []value
	instr *ssa.Defer
	tail  *deferred
}

type frame struct {
	i                *interpreter
	caller           *frame
	fn               *ssa.Function
	block, prevBlock *ssa.BasicBlock
	env              map[ssa.Value]value // dynamic values of SSA variables
	locals           []value
	defers           *deferred
	result           value
	panicking        bool
	panic            any
	phitemps         []value // temporaries for parallel phi assignment
}

func (fr *frame) get(key ssa.Value) value {
	switch key := key.(type) {
	case nil:
		// Hack; simplifies handling of optional attributes
		// such as ssa.Slice.{Low,High}.
		return nil
	case *ssa.Function, *ssa.Builtin:
		return key
	case *ssa.Const:
		return constValue(key)
	case *ssa.Global:
		if r, ok := fr.i.globals[key]; ok {
			return r
		}
	}
	if r, ok := fr.env[key]; ok {
		return r
	}
	panic(fmt.Sprintf("get: no value for %T: %v", key, key.Name()))
}

// runDefer runs a deferred call d.
// It always returns normally, but may set or clear fr.panic.
func (fr *frame) runDefer(d *deferred) {
	if fr.i.mode&EnableTracing != 0 {
		fmt.Fprintf(os.Stderr, "%s: invoking deferred function call\n",
			fr.i.prog.Fset.Position(d.instr.Pos()))
	}
	var ok bool
	defer func() {
		if !ok {
			// Deferred call created a new state of panic.
			fr.panicking = true
			fr.panic = recover()
		}
	}()
	call(fr.i, fr, d.instr.Pos(), d.fn, d.args)
	ok = true
}

// runDefers executes fr's deferred function calls in LIFO order.
//
// On entry, fr.panicking indicates a state of panic; if
// true, fr.panic contains the panic value.
//
// On completion, if a deferred call started a panic, or if no
// deferred call recovered from a previous state of panic, then
// runDefers itself panics after the last deferred call has run.
//
// If there was no initial state of panic, or it was recovered from,
// runDefers returns normally.
func (fr *frame) runDefers() {
	for d := fr.defers; d != nil; d = d.tail {
		fr.runDefer(d)
	}
	fr.defers = nil
	if fr.panicking {
		panic(fr.panic) // new panic, or still panicking
	}
}

// lookupMethod returns the method set for type typ, which may be one
// of the interpreter's fake types.
func lookupMethod(i *interpreter, typ types.Type, meth *types.Func) *ssa.Function {
	switch typ {
	case rtypeType:
		return i.rtypeMethods[meth.Id()]
	case errorType:
		return i.errorMethods[meth.Id()]
	}
	return i.prog.LookupMethod(typ, meth.Pkg(), meth.Name())
}

// visitInstr interprets a single ssa.Instruction within the activation
// record frame.  It returns a continuation value indicating where to
// read the next instruction from.
func visitInstr(fr *frame, instr ssa.Instruction) continuation {
	switch instr := instr.(type) {
	case *ssa.DebugRef:
		// no-op

	case *ssa.UnOp:
		fr.env[instr] = unop(instr, fr.get(instr.X))

	case *ssa.BinOp:
		fr.env[instr] = binop(instr.Op, instr.X.Type(), fr.get(instr.X), fr.get(instr.Y))

	case *ssa.Call:
		fn, args := prepareCall(fr, &instr.Call)
		fr.env[instr] = call(fr.i, fr, instr.Pos(), fn, args)

	case *ssa.ChangeInterface:
		fr.env[instr] = fr.get(instr.X)

	case *ssa.ChangeType:
		fr.env[instr] = fr.get(instr.X) // (can't fail)

	case *ssa.Convert:
		fr.env[instr] = conv(instr.Type(), instr.X.Type(), fr.get(instr.X))

	case *ssa.SliceToArrayPointer:
		fr.env[instr] = sliceToArrayPointer(instr.Type(), instr.X.Type(), fr.get(instr.X))

	case *ssa.MakeInterface:
		fr.env[instr] = iface{t: instr.X.Type(), v: fr.get(instr.X)}

	case *ssa.Extract:
		fr.env[instr] = fr.get(instr.Tuple).(tuple)[instr.Index]

	case *ssa.Slice:
		fr.env[instr] = slice(fr.get(instr.X), fr.get(instr.Low), fr.get(instr.High), fr.get(instr.Max))

	case *ssa.Return:
		switch len(instr.Results) {
		case 0:
		case 1:
			fr.result = fr.get(instr.Results[0])
		default:
			var res []value
			for _, r := range instr.Results {
				res = append(res, fr.get(r))
			}
			fr.result = tuple(res)
		}
		fr.block = nil
		return kReturn

	case *ssa.RunDefers:
		fr.runDefers()

	case *ssa.Panic:
		panic(targetPanic{fr.get(instr.X)})

	case *ssa.Send:
		fr.get(instr.Chan).(chan value) <- fr.get(instr.X)

	case *ssa.Store:
		store(typeparams.MustDeref(instr.Addr.Type()), fr.get(instr.Addr).(*value), fr.get(instr.Val))

	case *ssa.If:
		succ := 1
		if fr.get(instr.Cond).(bool) {
			succ = 0
		}
		fr.prevBlock, fr.block = fr.block, fr.block.Succs[succ]
		return kJump

	case *ssa.Jump:
		fr.prevBlock, fr.block = fr.block, fr.block.Succs[0]
		return kJump

	case *ssa.Defer:
		fn, args := prepareCall(fr, &instr.Call)
		defers := &fr.defers
		if into := fr.get(instr.DeferStack); into != nil {
			defers = into.(**deferred)
		}
		*defers = &deferred{
			fn:    fn,
			args:  args,
			instr: instr,
			tail:  *defers,
		}

	case *ssa.Go:
		fn, args := prepareCall(fr, &instr.Call)
		atomic.AddInt32(&fr.i.goroutines, 1)
		go func() {
			call(fr.i, nil, instr.Pos(), fn, args)
			atomic.AddInt32(&fr.i.goroutines, -1)
		}()

	case *ssa.MakeChan:
		fr.env[instr] = make(chan value, asInt64(fr.get(instr.Size)))

	case *ssa.Alloc:
		var addr *value
		if instr.Heap {
			// new
			addr = new(value)
			fr.env[instr] = addr
		} else {
			// local
			addr = fr.env[instr].(*value)
		}
		*addr = zero(typeparams.MustDeref(instr.Type()))

	case *ssa.MakeSlice:
		slice := make([]value, asInt64(fr.get(instr.Cap)))
		tElt := instr.Type().Underlying().(*types.Slice).Elem()
		for i := range slice {
			slice[i] = zero(tElt)
		}
		fr.env[instr] = slice[:asInt64(fr.get(instr.Len))]

	case *ssa.MakeMap:
		var reserve int64
		if instr.Reserve != nil {
			reserve = asInt64(fr.get(instr.Reserve))
		}
		if !fitsInt(reserve, fr.i.sizes) {
			panic(fmt.Sprintf("ssa.MakeMap.Reserve value %d does not fit in int", reserve))
		}
		fr.env[instr] = makeMap(instr.Type().Underlying().(*types.Map).Key(), reserve)

	case *ssa.Range:
		fr.env[instr] = rangeIter(fr.get(instr.X))

	case *ssa.Next:
		fr.env[instr] = fr.get(instr.Iter).(iter).next()

	case *ssa.FieldAddr:
		fr.env[instr] = &(*fr.get(instr.X).(*value)).(structure)[instr.Field]

	case *ssa.Field:
		fr.env[instr] = fr.get(instr.X).(structure)[instr.Field]

	case *ssa.IndexAddr:
		x := fr.get(instr.X)
		idx := fr.get(instr.Index)
		switch x := x.(type) {
		case []value:
			fr.env[instr] = &x[asInt64(idx)]
		case *value: // *array
			fr.env[instr] = &(*x).(array)[asInt64(idx)]
		default:
			panic(fmt.Sprintf("unexpected x type in IndexAddr: %T", x))
		}

	case *ssa.Index:
		x := fr.get(instr.X)
		idx := fr.get(instr.Index)

		switch x := x.(type) {
		case array:
			fr.env[instr] = x[asInt64(idx)]
		case string:
			fr.env[instr] = x[asInt64(idx)]
		default:
			panic(fmt.Sprintf("unexpected x type in Index: %T", x))
		}

	case *ssa.Lookup:
		fr.env[instr] = lookup(instr, fr.get(instr.X), fr.get(instr.Index))

	case *ssa.MapUpdate:
		m := fr.get(instr.Map)
		key := fr.get(instr.Key)
		v := fr.get(instr.Value)
		switch m := m.(type) {
		case map[value]value:
			m[key] = v
		case *hashmap:
			m.insert(key.(hashable), v)
		default:
			panic(fmt.Sprintf("illegal map type: %T", m))
		}

	case *ssa.TypeAssert:
		fr.env[instr] = typeAssert(instr, fr.get(instr.X).(iface))

	case *ssa.MakeClosure:
		var bindings []value
		for _, binding := range instr.Bindings {
			bindings = append(bindings, fr.get(binding))
		}
		fr.env[instr] = &closure{instr.Fn.(*ssa.Function), bindings}

	case *ssa.Phi:
		log.Fatal("unreachable") // phis are processed at block entry

	case *ssa.Select:
		var cases []reflect.SelectCase
		if !instr.Blocking {
			cases = append(cases, reflect.SelectCase{
				Dir: reflect.SelectDefault,
			})
		}
		for _, state := range instr.States {
			var dir reflect.SelectDir
			if state.Dir == types.RecvOnly {
				dir = reflect.SelectRecv
			} else {
				dir = reflect.SelectSend
			}
			var send reflect.Value
			if state.Send != nil {
				send = reflect.ValueOf(fr.get(state.Send))
			}
			cases = append(cases, reflect.SelectCase{
				Dir:  dir,
				Chan: reflect.ValueOf(fr.get(state.Chan)),
				Send: send,
			})
		}
		chosen, recv, recvOk := reflect.Select(cases)
		if !instr.Blocking {
			chosen-- // default case should have index -1.
		}
		r := tuple{chosen, recvOk}
		for i, st := range instr.States {
			if st.Dir == types.RecvOnly {
				var v value
				if i == chosen && recvOk {
					// No need to copy since send makes an unaliased copy.
					v = recv.Interface().(value)
				} else {
					v = zero(st.Chan.Type().Underlying().(*types.Chan).Elem())
				}
				r = append(r, v)
			}
		}
		fr.env[instr] = r

	default:
		panic(fmt.Sprintf("unexpected instruction: %T", instr))
	}

	// if val, ok := instr.(ssa.Value); ok {
	// 	fmt.Println(toString(fr.env[val])) // debugging
	// }

	return kNext
}

// prepareCall determines the function value and argument values for a
// function call in a Call, Go or Defer instruction, performing
// interface method lookup if needed.
func prepareCall(fr *frame, call *ssa.CallCommon) (fn value, args []value) {
	v := fr.get(call.Value)
	if call.Method == nil {
		// Function call.
		fn = v
	} else {
		// Interface method invocation.
		recv := v.(iface)
		if recv.t == nil {
			panic("method invoked on nil interface")
		}
		if f := lookupMethod(fr.i, recv.t, call.Method); f == nil {
			// Unreachable in well-typed programs.
			panic(fmt.Sprintf("method set for dynamic type %v does not contain %s", recv.t, call.Method))
		} else {
			fn = f
		}
		args = append(args, recv.v)
	}
	for _, arg := range call.Args {
		args = append(args, fr.get(arg))
	}
	return
}

// call interprets a call to a function (function, builtin or closure)
// fn with arguments args, returning its result.
// callpos is the position of the callsite.
func call(i *interpreter, caller *frame, callpos token.Pos, fn value, args []value) value {
	switch fn := fn.(type) {
	case *ssa.Function:
		if fn == nil {
			panic("call of nil function") // nil of func type
		}
		return callSSA(i, caller, callpos, fn, args, nil)
	case *closure:
		return callSSA(i, caller, callpos, fn.Fn, args, fn.Env)
	case *ssa.Builtin:
		return callBuiltin(caller, fn, args)
	}
	panic(fmt.Sprintf("cannot call %T", fn))
}

func loc(fset *token.FileSet, pos token.Pos) string {
	if pos == token.NoPos {
		return ""
	}
	return " at " + fset.Position(pos).String()
}

// callSSA interprets a call to function fn with arguments args,
// and lexical environment env, returning its result.
// callpos is the position of the callsite.
func callSSA(i *interpreter, caller *frame, callpos token.Pos, fn *ssa.Function, args []value, env []value) value {
	if i.mode&EnableTracing != 0 {
		fset := fn.Prog.Fset
		// TODO(adonovan): fix: loc() lies for external functions.
		fmt.Fprintf(os.Stderr, "Entering %s%s.\n", fn, loc(fset, fn.Pos()))
		suffix := ""
		if caller != nil {
			suffix = ", resuming " + caller.fn.String() + loc(fset, callpos)
		}
		defer fmt.Fprintf(os.Stderr, "Leaving %s%s.\n", fn, suffix)
	}
	fr := &frame{
		i:      i,
		caller: caller, // for panic/recover
		fn:     fn,
	}
	if fn.Parent() == nil {
		name := fn.String()
		if ext := externals[name]; ext != nil {
			if i.mode&EnableTracing != 0 {
				fmt.Fprintln(os.Stderr, "\t(external)")
			}
			return ext(fr, args)
		}
		if fn.Blocks == nil {
			panic("no code for function: " + name)
		}
	}

	// generic function body?
	if fn.TypeParams().Len() > 0 && len(fn.TypeArgs()) == 0 {
		panic("interp requires ssa.BuilderMode to include InstantiateGenerics to execute generics")
	}

	fr.env = make(map[ssa.Value]value)
	fr.block = fn.Blocks[0]
	fr.locals = make([]value, len(fn.Locals))
	for i, l := range fn.Locals {
		fr.locals[i] = zero(typeparams.MustDeref(l.Type()))
		fr.env[l] = &fr.locals[i]
	}
	for i, p := range fn.Params {
		fr.env[p] = args[i]
	}
	for i, fv := range fn.FreeVars {
		fr.env[fv] = env[i]
	}
	for fr.block != nil {
		runFrame(fr)
	}
	// Destroy the locals to avoid accidental use after return.
	for i := range fn.Locals {
		fr.locals[i] = bad{}
	}
	return fr.result
}

// runFrame executes SSA instructions starting at fr.block and
// continuing until a return, a panic, or a recovered panic.
//
// After a panic, runFrame panics.
//
// After a normal return, fr.result contains the result of the call
// and fr.block is nil.
//
// A recovered panic in a function without named return parameters
// (NRPs) becomes a normal return of the zero value of the function's
// result type.
//
// After a recovered panic in a function with NRPs, fr.result is
// undefined and fr.block contains the block at which to resume
// control.
func runFrame(fr *frame) {
	defer func() {
		if fr.block == nil {
			return // normal return
		}
		if fr.i.mode&DisableRecover != 0 {
			return // let interpreter crash
		}
		fr.panicking = true
		fr.panic = recover()
		if fr.i.mode&EnableTracing != 0 {
			fmt.Fprintf(os.Stderr, "Panicking: %T %v.\n", fr.panic, fr.panic)
		}
		fr.runDefers()
		fr.block = fr.fn.Recover
	}()

	for {
		if fr.i.mode&EnableTracing != 0 {
			fmt.Fprintf(os.Stderr, ".%s:\n", fr.block)
		}

		nonPhis := executePhis(fr)
		for _, instr := range nonPhis {
			if fr.i.mode&EnableTracing != 0 {
				if v, ok := instr.(ssa.Value); ok {
					fmt.Fprintln(os.Stderr, "\t", v.Name(), "=", instr)
				} else {
					fmt.Fprintln(os.Stderr, "\t", instr)
				}
			}
			if visitInstr(fr, instr) == kReturn {
				return
			}
			// Inv: kNext (continue) or kJump (last instr)
		}
	}
}

// executePhis executes the phi-nodes at the start of the current
// block and returns the non-phi instructions.
func executePhis(fr *frame) []ssa.Instruction {
	firstNonPhi := -1
	for i, instr := range fr.block.Instrs {
		if _, ok := instr.(*ssa.Phi); !ok {
			firstNonPhi = i
			break
		}
	}
	// Inv: 0 <= firstNonPhi; every block contains a non-phi.

	nonPhis := fr.block.Instrs[firstNonPhi:]
	if firstNonPhi > 0 {
		phis := fr.block.Instrs[:firstNonPhi]
		// Execute parallel assignment of phis.
		//
		// See "the swap problem" in Briggs et al's "Practical Improvements
		// to the Construction and Destruction of SSA Form" for discussion.
		predIndex := slices.Index(fr.block.Preds, fr.prevBlock)
		fr.phitemps = fr.phitemps[:0]
		for _, phi := range phis {
			phi := phi.(*ssa.Phi)
			if fr.i.mode&EnableTracing != 0 {
				fmt.Fprintln(os.Stderr, "\t", phi.Name(), "=", phi)
			}
			fr.phitemps = append(fr.phitemps, fr.get(phi.Edges[predIndex]))
		}
		for i, phi := range phis {
			fr.env[phi.(*ssa.Phi)] = fr.phitemps[i]
		}
	}
	return nonPhis
}

// doRecover implements the recover() built-in.
func doRecover(caller *frame) value {
	// recover() must be exactly one level beneath the deferred
	// function (two levels beneath the panicking function) to
	// have any effect.  Thus we ignore both "defer recover()" and
	// "defer f() -> g() -> recover()".
	if caller.i.mode&DisableRecover == 0 &&
		caller != nil && !caller.panicking &&
		caller.caller != nil && caller.caller.panicking {
		caller.caller.panicking = false
		p := caller.caller.panic
		caller.caller.panic = nil

		// TODO(adonovan): support runtime.Goexit.
		switch p := p.(type) {
		case targetPanic:
			// The target program explicitly called panic().
			return p.v
		case runtime.Error:
			// The interpreter encountered a runtime error.
			return iface{caller.i.runtimeErrorString, p.Error()}
		case string:
			// The interpreter explicitly called panic().
			return iface{caller.i.runtimeErrorString, p}
		default:
			panic(fmt.Sprintf("unexpected panic type %T in target call to recover()", p))
		}
	}
	return iface{}
}

// Interpret interprets the Go program whose main package is mainpkg.
// mode specifies various interpreter options.  filename and args are
// the initial values of os.Args for the target program.  sizes is the
// effective type-sizing function for this program.
//
// Interpret returns the exit code of the program: 2 for panic (like
// gc does), or the argument to os.Exit for normal termination.
//
// The SSA program must include the "runtime" package.
//
// Type parameterized functions must have been built with
// InstantiateGenerics in the ssa.BuilderMode to be interpreted.
func Interpret(mainpkg *ssa.Package, mode Mode, sizes types.Sizes, filename string, args []string) (exitCode int) {
	i := &interpreter{
		prog:       mainpkg.Prog,
		globals:    make(map[*ssa.Global]*value),
		mode:       mode,
		sizes:      sizes,
		goroutines: 1,
	}
	runtimePkg := i.prog.ImportedPackage("runtime")
	if runtimePkg == nil {
		panic("ssa.Program doesn't include runtime package")
	}
	i.runtimeErrorString = runtimePkg.Type("errorString").Object().Type()

	initReflect(i)

	i.osArgs = append(i.osArgs, filename)
	for _, arg := range args {
		i.osArgs = append(i.osArgs, arg)
	}

	for _, pkg := range i.prog.AllPackages() {
		// Initialize global storage.
		for _, m := range pkg.Members {
			switch v := m.(type) {
			case *ssa.Global:
				cell := zero(typeparams.MustDeref(v.Type()))
				i.globals[v] = &cell
			}
		}
	}

	// Top-level error handler.
	exitCode = 2
	defer func() {
		if exitCode != 2 || i.mode&DisableRecover != 0 {
			return
		}
		switch p := recover().(type) {
		case exitPanic:
			exitCode = int(p)
			return
		case targetPanic:
			fmt.Fprintln(os.Stderr, "panic:", toString(p.v))
		case runtime.Error:
			fmt.Fprintln(os.Stderr, "panic:", p.Error())
		case string:
			fmt.Fprintln(os.Stderr, "panic:", p)
		default:
			fmt.Fprintf(os.Stderr, "panic: unexpected type: %T: %v\n", p, p)
		}

		// TODO(adonovan): dump panicking interpreter goroutine?
		// buf := make([]byte, 0x10000)
		// runtime.Stack(buf, false)
		// fmt.Fprintln(os.Stderr, string(buf))
		// (Or dump panicking target goroutine?)
	}()

	// Run!
	call(i, nil, token.NoPos, mainpkg.Func("init"), nil)
	if mainFn := mainpkg.Func("main"); mainFn != nil {
		call(i, nil, token.NoPos, mainFn, nil)
		exitCode = 0
	} else {
		fmt.Fprintln(os.Stderr, "No main function.")
		exitCode = 1
	}
	return
}


================================================
FILE: go/ssa/interp/interp_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp_test

// This test runs the SSA interpreter over sample Go programs.
// Because the interpreter requires intrinsics for assembly
// functions and many low-level runtime routines, it is inherently
// not robust to evolutionary change in the standard library.
// Therefore the test cases are restricted to programs that
// use a fake standard library in testdata/src containing a tiny
// subset of simple functions useful for writing assertions.
//
// We no longer attempt to interpret any real standard packages such as
// fmt or testing, as it proved too fragile.

import (
	"bytes"
	"fmt"
	"go/build"
	"go/types"
	"io"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"
	"unsafe"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/interp"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
)

// Each line contains a space-separated list of $GOROOT/test/
// filenames comprising the main package of a program.
// They are ordered quickest-first, roughly.
//
// If a test in this list fails spuriously, remove it.
var gorootTestTests = []string{
	"235.go",
	"alias1.go",
	"func5.go",
	"func6.go",
	"func7.go",
	"func8.go",
	"helloworld.go",
	"varinit.go",
	"escape3.go",
	"initcomma.go",
	"cmp.go",
	"compos.go",
	"turing.go",
	"indirect.go",
	"complit.go",
	"for.go",
	"struct0.go",
	"intcvt.go",
	"printbig.go",
	"deferprint.go",
	"escape.go",
	"range.go",
	"const4.go",
	"float_lit.go",
	"bigalg.go",
	"decl.go",
	"if.go",
	"named.go",
	"bigmap.go",
	"func.go",
	"reorder2.go",
	"gc.go",
	"simassign.go",
	"iota.go",
	"nilptr2.go",
	"utf.go",
	"method.go",
	"char_lit.go",
	"env.go",
	"int_lit.go",
	"string_lit.go",
	"defer.go",
	"typeswitch.go",
	"stringrange.go",
	"reorder.go",
	"method3.go",
	"literal.go",
	"nul1.go", // doesn't actually assert anything (errorcheckoutput)
	"zerodivide.go",
	"convert.go",
	"convT2X.go",
	"switch.go",
	"ddd.go",
	"blank.go", // partly disabled
	"closedchan.go",
	"divide.go",
	"rename.go",
	"nil.go",
	"recover1.go",
	"recover2.go",
	"recover3.go",
	"typeswitch1.go",
	"floatcmp.go",
	"crlf.go", // doesn't actually assert anything (runoutput)
}

// These are files in testdata/.
var testdataTests = []string{
	"boundmeth.go",
	"complit.go",
	"convert.go",
	"coverage.go",
	"deepequal.go",
	"defer.go",
	"fieldprom.go",
	"fixedbugs/issue52342.go",
	"fixedbugs/issue52835.go",
	"fixedbugs/issue55086.go",
	"fixedbugs/issue55115.go",
	"fixedbugs/issue66783.go",
	"fixedbugs/issue69929.go",
	"forvarlifetime_go122.go",
	"forvarlifetime_old.go",
	"ifaceconv.go",
	"ifaceprom.go",
	"initorder.go",
	"methprom.go",
	"minmax.go",
	"mrvchain.go",
	"newexpr_go126.go",
	"range.go",
	"rangeoverint.go",
	"rangevarlifetime_go122.go",
	"rangevarlifetime_old.go",
	"recover.go",
	"reflect.go",
	"slice2array.go",
	"slice2arrayptr.go",
	"static.go",
	"typeassert.go",
	"width32.go",
	"zeros.go",
}

func init() {
	// GOROOT/test used to assume that GOOS and GOARCH were explicitly set in the
	// environment, so do that here for TestGorootTest.
	os.Setenv("GOOS", runtime.GOOS)
	os.Setenv("GOARCH", runtime.GOARCH)
}

// run runs a single test. On success it returns the captured std{out,err}.
func run(t *testing.T, input string, goroot string) string {
	testenv.NeedsExec(t) // really we just need os.Pipe, but os/exec uses pipes

	t.Logf("Input: %s\n", input)

	start := time.Now()

	ctx := build.Default // copy
	ctx.GOROOT = goroot
	ctx.GOOS = runtime.GOOS
	ctx.GOARCH = runtime.GOARCH
	if filepath.Base(input) == "width32.go" && unsafe.Sizeof(int(0)) > 4 {
		t.Skipf("skipping: width32.go checks behavior for a 32-bit int")
	}

	gover := ""
	if p := testenv.Go1Point(); p > 0 {
		gover = fmt.Sprintf("go1.%d", p)
	}

	// Check build tags, since FromArgs doesn't do this part.
	// TODO(adonovan): use go/packages.
	if match, err := ctx.MatchFile(filepath.Dir(input), filepath.Base(input)); err != nil {
		t.Fatalf("MatchFile %v: %v", input, err)
	} else if !match {
		t.Skipf("file %s doesn't match this build configuration", input)
	}

	conf := loader.Config{Build: &ctx, TypeChecker: types.Config{GoVersion: gover}}
	if _, err := conf.FromArgs([]string{input}, true); err != nil {
		t.Fatalf("FromArgs(%s) failed: %s", input, err)
	}

	conf.Import("runtime")

	// Print a helpful hint if we don't make it to the end.
	var hint string
	defer func() {
		t.Logf("Duration: %v", time.Since(start))
		if hint != "" {
			t.Log("FAIL")
			t.Log(hint)
		} else {
			t.Log("PASS")
		}
	}()

	hint = fmt.Sprintf("To dump SSA representation, run:\n%% go build golang.org/x/tools/cmd/ssadump && ./ssadump -test -build=CFP %s\n", input)

	iprog, err := conf.Load()
	if err != nil {
		t.Fatalf("conf.Load(%s) failed: %s", input, err)
	}

	bmode := ssa.InstantiateGenerics | ssa.SanityCheckFunctions
	// bmode |= ssa.PrintFunctions // enable for debugging
	prog := ssautil.CreateProgram(iprog, bmode)
	prog.Build()

	mainPkg := prog.Package(iprog.Created[0].Pkg)
	if mainPkg == nil {
		t.Fatalf("not a main package: %s", input)
	}

	sizes := types.SizesFor("gc", ctx.GOARCH)
	if sizes.Sizeof(types.Typ[types.Int]) < 4 {
		panic("bogus SizesFor")
	}
	hint = fmt.Sprintf("To trace execution, run:\n%% go build golang.org/x/tools/cmd/ssadump && ./ssadump -build=C -test -run --interp=T %s\n", input)

	// Capture anything written by the interpreter to os.Std{out,err}
	// by temporarily redirecting them to a buffer via a pipe.
	//
	// While capturing is in effect, we must not write any
	// test-related stuff to stderr (including log.Print, t.Log, etc).
	var restore func() string // restore files and log+return the mixed out/err.
	{
		// Connect std{out,err} to pipe.
		r, w, err := os.Pipe()
		if err != nil {
			t.Fatalf("can't create pipe for stderr: %v", err)
		}
		savedStdout := os.Stdout
		savedStderr := os.Stderr
		os.Stdout = w
		os.Stderr = w

		// Buffer what is written.
		var buf strings.Builder
		done := make(chan struct{})
		go func() {
			if _, err := io.Copy(&buf, r); err != nil {
				fmt.Fprintf(savedStderr, "io.Copy: %v", err)
			}
			close(done)
		}()

		// Finally, restore the files and log what was captured.
		restore = func() string {
			os.Stdout = savedStdout
			os.Stderr = savedStderr
			w.Close()
			<-done
			captured := buf.String()
			t.Logf("Interpreter's stdout+stderr:\n%s", captured)
			return captured
		}
	}

	var imode interp.Mode // default mode
	// imode |= interp.DisableRecover // enable for debugging
	// imode |= interp.EnableTracing // enable for debugging
	exitCode := interp.Interpret(mainPkg, imode, sizes, input, []string{})
	capturedOutput := restore()
	if exitCode != 0 {
		t.Fatalf("interpreting %s: exit code was %d", input, exitCode)
	}
	// $GOROOT/test tests use this convention:
	if strings.Contains(capturedOutput, "BUG") {
		t.Fatalf("interpreting %s: exited zero but output contained 'BUG'", input)
	}

	hint = "" // call off the hounds

	return capturedOutput
}

// makeGoroot copies testdata/src into the "src" directory of a temporary
// location to mimic GOROOT/src, and adds a file "runtime/consts.go" containing
// declarations for GOOS and GOARCH that match the GOOS and GOARCH of this test.
//
// It returns the directory that should be used for GOROOT.
func makeGoroot(t *testing.T) string {
	goroot := t.TempDir()
	src := filepath.Join(goroot, "src")

	err := filepath.Walk("testdata/src", func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}

		rel, err := filepath.Rel("testdata/src", path)
		if err != nil {
			return err
		}
		targ := filepath.Join(src, rel)

		if info.IsDir() {
			return os.Mkdir(targ, info.Mode().Perm()|0700)
		}

		b, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		return os.WriteFile(targ, b, info.Mode().Perm())
	})
	if err != nil {
		t.Fatal(err)
	}

	constsGo := fmt.Sprintf(`package runtime
const GOOS = %q
const GOARCH = %q
`, runtime.GOOS, runtime.GOARCH)
	err = os.WriteFile(filepath.Join(src, "runtime/consts.go"), []byte(constsGo), 0644)
	if err != nil {
		t.Fatal(err)
	}

	return goroot
}

// TestTestdataFiles runs the interpreter on testdata/*.go.
func TestTestdataFiles(t *testing.T) {
	goroot := makeGoroot(t)
	for _, input := range testdataTests {
		t.Run(input, func(t *testing.T) {
			run(t, filepath.Join("testdata", input), goroot)
		})
	}
}

// TestGorootTest runs the interpreter on $GOROOT/test/*.go.
func TestGorootTest(t *testing.T) {
	testenv.NeedsGOROOTDir(t, "test")

	goroot := makeGoroot(t)
	for _, input := range gorootTestTests {
		t.Run(input, func(t *testing.T) {
			run(t, filepath.Join(build.Default.GOROOT, "test", input), goroot)
		})
	}
}

// TestTypeparamTest runs the interpreter on runnable examples
// in $GOROOT/test/typeparam/*.go.

func TestTypeparamTest(t *testing.T) {
	testenv.NeedsGOROOTDir(t, "test")

	if runtime.GOARCH == "wasm" {
		// See ssa/TestTypeparamTest.
		t.Skip("Consistent flakes on wasm (e.g. https://go.dev/issues/64726)")
	}

	goroot := makeGoroot(t)

	// Skip known failures for the given reason.
	// TODO(taking): Address these.
	skip := map[string]string{
		"chans.go":      "interp tests do not support runtime.SetFinalizer",
		"issue23536.go": "unknown reason",
		"issue48042.go": "interp tests do not handle reflect.Value.SetInt",
		"issue47716.go": "interp tests do not handle unsafe.Sizeof",
		"issue50419.go": "interp tests do not handle dispatch to String() correctly",
		"issue51733.go": "interp does not handle unsafe casts",
		"ordered.go":    "math.NaN() comparisons not being handled correctly",
		"orderedmap.go": "interp tests do not support runtime.SetFinalizer",
		"stringer.go":   "unknown reason",
		"issue48317.go": "interp tests do not support encoding/json",
		"issue48318.go": "interp tests do not support encoding/json",
		"issue58513.go": "interp tests do not support runtime.Caller",
	}
	// Collect all of the .go files in dir that are runnable.
	dir := filepath.Join(build.Default.GOROOT, "test", "typeparam")
	list, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	for _, entry := range list {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".go") {
			continue // Consider standalone go files.
		}
		t.Run(entry.Name(), func(t *testing.T) {
			input := filepath.Join(dir, entry.Name())
			src, err := os.ReadFile(input)
			if err != nil {
				t.Fatal(err)
			}

			// Only build test files that can be compiled, or compiled and run.
			if !bytes.HasPrefix(src, []byte("// run")) || bytes.HasPrefix(src, []byte("// rundir")) {
				t.Logf("Not a `// run` file: %s", entry.Name())
				return
			}

			if reason := skip[entry.Name()]; reason != "" {
				t.Skipf("skipping: %s", reason)
			}

			run(t, input, goroot)
		})
	}
}


================================================
FILE: go/ssa/interp/map.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp

// Custom hashtable atop map.
// For use when the key's equivalence relation is not consistent with ==.

// The Go specification doesn't address the atomicity of map operations.
// The FAQ states that an implementation is permitted to crash on
// concurrent map access.

import (
	"go/types"
)

type hashable interface {
	hash(t types.Type) int
	eq(t types.Type, x any) bool
}

type entry struct {
	key   hashable
	value value
	next  *entry
}

// A hashtable atop the built-in map.  Since each bucket contains
// exactly one hash value, there's no need to perform hash-equality
// tests when walking the linked list.  Rehashing is done by the
// underlying map.
type hashmap struct {
	keyType types.Type
	table   map[int]*entry
	length  int // number of entries in map
}

// makeMap returns an empty initialized map of key type kt,
// preallocating space for reserve elements.
func makeMap(kt types.Type, reserve int64) value {
	if usesBuiltinMap(kt) {
		return make(map[value]value, reserve)
	}
	return &hashmap{keyType: kt, table: make(map[int]*entry, reserve)}
}

// delete removes the association for key k, if any.
func (m *hashmap) delete(k hashable) {
	if m != nil {
		hash := k.hash(m.keyType)
		head := m.table[hash]
		if head != nil {
			if k.eq(m.keyType, head.key) {
				m.table[hash] = head.next
				m.length--
				return
			}
			prev := head
			for e := head.next; e != nil; e = e.next {
				if k.eq(m.keyType, e.key) {
					prev.next = e.next
					m.length--
					return
				}
				prev = e
			}
		}
	}
}

// lookup returns the value associated with key k, if present, or
// value(nil) otherwise.
func (m *hashmap) lookup(k hashable) value {
	if m != nil {
		hash := k.hash(m.keyType)
		for e := m.table[hash]; e != nil; e = e.next {
			if k.eq(m.keyType, e.key) {
				return e.value
			}
		}
	}
	return nil
}

// insert updates the map to associate key k with value v.  If there
// was already an association for an eq() (though not necessarily ==)
// k, the previous key remains in the map and its associated value is
// updated.
func (m *hashmap) insert(k hashable, v value) {
	hash := k.hash(m.keyType)
	head := m.table[hash]
	for e := head; e != nil; e = e.next {
		if k.eq(m.keyType, e.key) {
			e.value = v
			return
		}
	}
	m.table[hash] = &entry{
		key:   k,
		value: v,
		next:  head,
	}
	m.length++
}

// len returns the number of key/value associations in the map.
func (m *hashmap) len() int {
	if m != nil {
		return m.length
	}
	return 0
}

// entries returns a rangeable map of entries.
func (m *hashmap) entries() map[int]*entry {
	if m != nil {
		return m.table
	}
	return nil
}


================================================
FILE: go/ssa/interp/ops.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp

import (
	"bytes"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"os"
	"reflect"
	"strings"
	"unsafe"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/typeparams"
)

// If the target program panics, the interpreter panics with this type.
type targetPanic struct {
	v value
}

func (p targetPanic) String() string {
	return toString(p.v)
}

// If the target program calls exit, the interpreter panics with this type.
type exitPanic int

// constValue returns the value of the constant with the
// dynamic type tag appropriate for c.Type().
func constValue(c *ssa.Const) value {
	if c.Value == nil {
		return zero(c.Type()) // typed zero
	}
	// c is not a type parameter so it's underlying type is basic.

	if t, ok := c.Type().Underlying().(*types.Basic); ok {
		// TODO(adonovan): eliminate untyped constants from SSA form.
		switch t.Kind() {
		case types.Bool, types.UntypedBool:
			return constant.BoolVal(c.Value)
		case types.Int, types.UntypedInt:
			// Assume sizeof(int) is same on host and target.
			return int(c.Int64())
		case types.Int8:
			return int8(c.Int64())
		case types.Int16:
			return int16(c.Int64())
		case types.Int32, types.UntypedRune:
			return int32(c.Int64())
		case types.Int64:
			return c.Int64()
		case types.Uint:
			// Assume sizeof(uint) is same on host and target.
			return uint(c.Uint64())
		case types.Uint8:
			return uint8(c.Uint64())
		case types.Uint16:
			return uint16(c.Uint64())
		case types.Uint32:
			return uint32(c.Uint64())
		case types.Uint64:
			return c.Uint64()
		case types.Uintptr:
			// Assume sizeof(uintptr) is same on host and target.
			return uintptr(c.Uint64())
		case types.Float32:
			return float32(c.Float64())
		case types.Float64, types.UntypedFloat:
			return c.Float64()
		case types.Complex64:
			return complex64(c.Complex128())
		case types.Complex128, types.UntypedComplex:
			return c.Complex128()
		case types.String, types.UntypedString:
			if c.Value.Kind() == constant.String {
				return constant.StringVal(c.Value)
			}
			return string(rune(c.Int64()))
		}
	}

	panic(fmt.Sprintf("constValue: %s", c))
}

// fitsInt returns true if x fits in type int according to sizes.
func fitsInt(x int64, sizes types.Sizes) bool {
	intSize := sizes.Sizeof(types.Typ[types.Int])
	if intSize < sizes.Sizeof(types.Typ[types.Int64]) {
		maxInt := int64(1)<<((intSize*8)-1) - 1
		minInt := -int64(1) << ((intSize * 8) - 1)
		return minInt <= x && x <= maxInt
	}
	return true
}

// asInt64 converts x, which must be an integer, to an int64.
//
// Callers that need a value directly usable as an int should combine this with fitsInt().
func asInt64(x value) int64 {
	switch x := x.(type) {
	case int:
		return int64(x)
	case int8:
		return int64(x)
	case int16:
		return int64(x)
	case int32:
		return int64(x)
	case int64:
		return x
	case uint:
		return int64(x)
	case uint8:
		return int64(x)
	case uint16:
		return int64(x)
	case uint32:
		return int64(x)
	case uint64:
		return int64(x)
	case uintptr:
		return int64(x)
	}
	panic(fmt.Sprintf("cannot convert %T to int64", x))
}

// asUint64 converts x, which must be an unsigned integer, to a uint64
// suitable for use as a bitwise shift count.
func asUint64(x value) uint64 {
	switch x := x.(type) {
	case uint:
		return uint64(x)
	case uint8:
		return uint64(x)
	case uint16:
		return uint64(x)
	case uint32:
		return uint64(x)
	case uint64:
		return x
	case uintptr:
		return uint64(x)
	}
	panic(fmt.Sprintf("cannot convert %T to uint64", x))
}

// asUnsigned returns the value of x, which must be an integer type, as its equivalent unsigned type,
// and returns true if x is non-negative.
func asUnsigned(x value) (value, bool) {
	switch x := x.(type) {
	case int:
		return uint(x), x >= 0
	case int8:
		return uint8(x), x >= 0
	case int16:
		return uint16(x), x >= 0
	case int32:
		return uint32(x), x >= 0
	case int64:
		return uint64(x), x >= 0
	case uint, uint8, uint32, uint64, uintptr:
		return x, true
	}
	panic(fmt.Sprintf("cannot convert %T to unsigned", x))
}

// zero returns a new "zero" value of the specified type.
func zero(t types.Type) value {
	switch t := t.(type) {
	case *types.Basic:
		if t.Kind() == types.UntypedNil {
			panic("untyped nil has no zero value")
		}
		if t.Info()&types.IsUntyped != 0 {
			// TODO(adonovan): make it an invariant that
			// this is unreachable.  Currently some
			// constants have 'untyped' types when they
			// should be defaulted by the typechecker.
			t = types.Default(t).(*types.Basic)
		}
		switch t.Kind() {
		case types.Bool:
			return false
		case types.Int:
			return int(0)
		case types.Int8:
			return int8(0)
		case types.Int16:
			return int16(0)
		case types.Int32:
			return int32(0)
		case types.Int64:
			return int64(0)
		case types.Uint:
			return uint(0)
		case types.Uint8:
			return uint8(0)
		case types.Uint16:
			return uint16(0)
		case types.Uint32:
			return uint32(0)
		case types.Uint64:
			return uint64(0)
		case types.Uintptr:
			return uintptr(0)
		case types.Float32:
			return float32(0)
		case types.Float64:
			return float64(0)
		case types.Complex64:
			return complex64(0)
		case types.Complex128:
			return complex128(0)
		case types.String:
			return ""
		case types.UnsafePointer:
			return unsafe.Pointer(nil)
		default:
			panic(fmt.Sprint("zero for unexpected type:", t))
		}
	case *types.Pointer:
		return (*value)(nil)
	case *types.Array:
		a := make(array, t.Len())
		for i := range a {
			a[i] = zero(t.Elem())
		}
		return a
	case *types.Named:
		return zero(t.Underlying())
	case *types.Alias:
		return zero(types.Unalias(t))
	case *types.Interface:
		return iface{} // nil type, methodset and value
	case *types.Slice:
		return []value(nil)
	case *types.Struct:
		s := make(structure, t.NumFields())
		for i := range s {
			s[i] = zero(t.Field(i).Type())
		}
		return s
	case *types.Tuple:
		if t.Len() == 1 {
			return zero(t.At(0).Type())
		}
		s := make(tuple, t.Len())
		for i := range s {
			s[i] = zero(t.At(i).Type())
		}
		return s
	case *types.Chan:
		return chan value(nil)
	case *types.Map:
		if usesBuiltinMap(t.Key()) {
			return map[value]value(nil)
		}
		return (*hashmap)(nil)
	case *types.Signature:
		return (*ssa.Function)(nil)
	}
	panic(fmt.Sprint("zero: unexpected ", t))
}

// slice returns x[lo:hi:max].  Any of lo, hi and max may be nil.
func slice(x, lo, hi, max value) value {
	var Len, Cap int
	switch x := x.(type) {
	case string:
		Len = len(x)
	case []value:
		Len = len(x)
		Cap = cap(x)
	case *value: // *array
		a := (*x).(array)
		Len = len(a)
		Cap = cap(a)
	}

	l := int64(0)
	if lo != nil {
		l = asInt64(lo)
	}

	h := int64(Len)
	if hi != nil {
		h = asInt64(hi)
	}

	m := int64(Cap)
	if max != nil {
		m = asInt64(max)
	}

	switch x := x.(type) {
	case string:
		return x[l:h]
	case []value:
		return x[l:h:m]
	case *value: // *array
		a := (*x).(array)
		return []value(a)[l:h:m]
	}
	panic(fmt.Sprintf("slice: unexpected X type: %T", x))
}

// lookup returns x[idx] where x is a map.
func lookup(instr *ssa.Lookup, x, idx value) value {
	switch x := x.(type) { // map or string
	case map[value]value, *hashmap:
		var v value
		var ok bool
		switch x := x.(type) {
		case map[value]value:
			v, ok = x[idx]
		case *hashmap:
			v = x.lookup(idx.(hashable))
			ok = v != nil
		}
		if !ok {
			v = zero(instr.X.Type().Underlying().(*types.Map).Elem())
		}
		if instr.CommaOk {
			v = tuple{v, ok}
		}
		return v
	}
	panic(fmt.Sprintf("unexpected x type in Lookup: %T", x))
}

// binop implements all arithmetic and logical binary operators for
// numeric datatypes and strings.  Both operands must have identical
// dynamic type.
func binop(op token.Token, t types.Type, x, y value) value {
	switch op {
	case token.ADD:
		switch x.(type) {
		case int:
			return x.(int) + y.(int)
		case int8:
			return x.(int8) + y.(int8)
		case int16:
			return x.(int16) + y.(int16)
		case int32:
			return x.(int32) + y.(int32)
		case int64:
			return x.(int64) + y.(int64)
		case uint:
			return x.(uint) + y.(uint)
		case uint8:
			return x.(uint8) + y.(uint8)
		case uint16:
			return x.(uint16) + y.(uint16)
		case uint32:
			return x.(uint32) + y.(uint32)
		case uint64:
			return x.(uint64) + y.(uint64)
		case uintptr:
			return x.(uintptr) + y.(uintptr)
		case float32:
			return x.(float32) + y.(float32)
		case float64:
			return x.(float64) + y.(float64)
		case complex64:
			return x.(complex64) + y.(complex64)
		case complex128:
			return x.(complex128) + y.(complex128)
		case string:
			return x.(string) + y.(string)
		}

	case token.SUB:
		switch x.(type) {
		case int:
			return x.(int) - y.(int)
		case int8:
			return x.(int8) - y.(int8)
		case int16:
			return x.(int16) - y.(int16)
		case int32:
			return x.(int32) - y.(int32)
		case int64:
			return x.(int64) - y.(int64)
		case uint:
			return x.(uint) - y.(uint)
		case uint8:
			return x.(uint8) - y.(uint8)
		case uint16:
			return x.(uint16) - y.(uint16)
		case uint32:
			return x.(uint32) - y.(uint32)
		case uint64:
			return x.(uint64) - y.(uint64)
		case uintptr:
			return x.(uintptr) - y.(uintptr)
		case float32:
			return x.(float32) - y.(float32)
		case float64:
			return x.(float64) - y.(float64)
		case complex64:
			return x.(complex64) - y.(complex64)
		case complex128:
			return x.(complex128) - y.(complex128)
		}

	case token.MUL:
		switch x.(type) {
		case int:
			return x.(int) * y.(int)
		case int8:
			return x.(int8) * y.(int8)
		case int16:
			return x.(int16) * y.(int16)
		case int32:
			return x.(int32) * y.(int32)
		case int64:
			return x.(int64) * y.(int64)
		case uint:
			return x.(uint) * y.(uint)
		case uint8:
			return x.(uint8) * y.(uint8)
		case uint16:
			return x.(uint16) * y.(uint16)
		case uint32:
			return x.(uint32) * y.(uint32)
		case uint64:
			return x.(uint64) * y.(uint64)
		case uintptr:
			return x.(uintptr) * y.(uintptr)
		case float32:
			return x.(float32) * y.(float32)
		case float64:
			return x.(float64) * y.(float64)
		case complex64:
			return x.(complex64) * y.(complex64)
		case complex128:
			return x.(complex128) * y.(complex128)
		}

	case token.QUO:
		switch x.(type) {
		case int:
			return x.(int) / y.(int)
		case int8:
			return x.(int8) / y.(int8)
		case int16:
			return x.(int16) / y.(int16)
		case int32:
			return x.(int32) / y.(int32)
		case int64:
			return x.(int64) / y.(int64)
		case uint:
			return x.(uint) / y.(uint)
		case uint8:
			return x.(uint8) / y.(uint8)
		case uint16:
			return x.(uint16) / y.(uint16)
		case uint32:
			return x.(uint32) / y.(uint32)
		case uint64:
			return x.(uint64) / y.(uint64)
		case uintptr:
			return x.(uintptr) / y.(uintptr)
		case float32:
			return x.(float32) / y.(float32)
		case float64:
			return x.(float64) / y.(float64)
		case complex64:
			return x.(complex64) / y.(complex64)
		case complex128:
			return x.(complex128) / y.(complex128)
		}

	case token.REM:
		switch x.(type) {
		case int:
			return x.(int) % y.(int)
		case int8:
			return x.(int8) % y.(int8)
		case int16:
			return x.(int16) % y.(int16)
		case int32:
			return x.(int32) % y.(int32)
		case int64:
			return x.(int64) % y.(int64)
		case uint:
			return x.(uint) % y.(uint)
		case uint8:
			return x.(uint8) % y.(uint8)
		case uint16:
			return x.(uint16) % y.(uint16)
		case uint32:
			return x.(uint32) % y.(uint32)
		case uint64:
			return x.(uint64) % y.(uint64)
		case uintptr:
			return x.(uintptr) % y.(uintptr)
		}

	case token.AND:
		switch x.(type) {
		case int:
			return x.(int) & y.(int)
		case int8:
			return x.(int8) & y.(int8)
		case int16:
			return x.(int16) & y.(int16)
		case int32:
			return x.(int32) & y.(int32)
		case int64:
			return x.(int64) & y.(int64)
		case uint:
			return x.(uint) & y.(uint)
		case uint8:
			return x.(uint8) & y.(uint8)
		case uint16:
			return x.(uint16) & y.(uint16)
		case uint32:
			return x.(uint32) & y.(uint32)
		case uint64:
			return x.(uint64) & y.(uint64)
		case uintptr:
			return x.(uintptr) & y.(uintptr)
		}

	case token.OR:
		switch x.(type) {
		case int:
			return x.(int) | y.(int)
		case int8:
			return x.(int8) | y.(int8)
		case int16:
			return x.(int16) | y.(int16)
		case int32:
			return x.(int32) | y.(int32)
		case int64:
			return x.(int64) | y.(int64)
		case uint:
			return x.(uint) | y.(uint)
		case uint8:
			return x.(uint8) | y.(uint8)
		case uint16:
			return x.(uint16) | y.(uint16)
		case uint32:
			return x.(uint32) | y.(uint32)
		case uint64:
			return x.(uint64) | y.(uint64)
		case uintptr:
			return x.(uintptr) | y.(uintptr)
		}

	case token.XOR:
		switch x.(type) {
		case int:
			return x.(int) ^ y.(int)
		case int8:
			return x.(int8) ^ y.(int8)
		case int16:
			return x.(int16) ^ y.(int16)
		case int32:
			return x.(int32) ^ y.(int32)
		case int64:
			return x.(int64) ^ y.(int64)
		case uint:
			return x.(uint) ^ y.(uint)
		case uint8:
			return x.(uint8) ^ y.(uint8)
		case uint16:
			return x.(uint16) ^ y.(uint16)
		case uint32:
			return x.(uint32) ^ y.(uint32)
		case uint64:
			return x.(uint64) ^ y.(uint64)
		case uintptr:
			return x.(uintptr) ^ y.(uintptr)
		}

	case token.AND_NOT:
		switch x.(type) {
		case int:
			return x.(int) &^ y.(int)
		case int8:
			return x.(int8) &^ y.(int8)
		case int16:
			return x.(int16) &^ y.(int16)
		case int32:
			return x.(int32) &^ y.(int32)
		case int64:
			return x.(int64) &^ y.(int64)
		case uint:
			return x.(uint) &^ y.(uint)
		case uint8:
			return x.(uint8) &^ y.(uint8)
		case uint16:
			return x.(uint16) &^ y.(uint16)
		case uint32:
			return x.(uint32) &^ y.(uint32)
		case uint64:
			return x.(uint64) &^ y.(uint64)
		case uintptr:
			return x.(uintptr) &^ y.(uintptr)
		}

	case token.SHL:
		u, ok := asUnsigned(y)
		if !ok {
			panic("negative shift amount")
		}
		y := asUint64(u)
		switch x.(type) {
		case int:
			return x.(int) << y
		case int8:
			return x.(int8) << y
		case int16:
			return x.(int16) << y
		case int32:
			return x.(int32) << y
		case int64:
			return x.(int64) << y
		case uint:
			return x.(uint) << y
		case uint8:
			return x.(uint8) << y
		case uint16:
			return x.(uint16) << y
		case uint32:
			return x.(uint32) << y
		case uint64:
			return x.(uint64) << y
		case uintptr:
			return x.(uintptr) << y
		}

	case token.SHR:
		u, ok := asUnsigned(y)
		if !ok {
			panic("negative shift amount")
		}
		y := asUint64(u)
		switch x.(type) {
		case int:
			return x.(int) >> y
		case int8:
			return x.(int8) >> y
		case int16:
			return x.(int16) >> y
		case int32:
			return x.(int32) >> y
		case int64:
			return x.(int64) >> y
		case uint:
			return x.(uint) >> y
		case uint8:
			return x.(uint8) >> y
		case uint16:
			return x.(uint16) >> y
		case uint32:
			return x.(uint32) >> y
		case uint64:
			return x.(uint64) >> y
		case uintptr:
			return x.(uintptr) >> y
		}

	case token.LSS:
		switch x.(type) {
		case int:
			return x.(int) < y.(int)
		case int8:
			return x.(int8) < y.(int8)
		case int16:
			return x.(int16) < y.(int16)
		case int32:
			return x.(int32) < y.(int32)
		case int64:
			return x.(int64) < y.(int64)
		case uint:
			return x.(uint) < y.(uint)
		case uint8:
			return x.(uint8) < y.(uint8)
		case uint16:
			return x.(uint16) < y.(uint16)
		case uint32:
			return x.(uint32) < y.(uint32)
		case uint64:
			return x.(uint64) < y.(uint64)
		case uintptr:
			return x.(uintptr) < y.(uintptr)
		case float32:
			return x.(float32) < y.(float32)
		case float64:
			return x.(float64) < y.(float64)
		case string:
			return x.(string) < y.(string)
		}

	case token.LEQ:
		switch x.(type) {
		case int:
			return x.(int) <= y.(int)
		case int8:
			return x.(int8) <= y.(int8)
		case int16:
			return x.(int16) <= y.(int16)
		case int32:
			return x.(int32) <= y.(int32)
		case int64:
			return x.(int64) <= y.(int64)
		case uint:
			return x.(uint) <= y.(uint)
		case uint8:
			return x.(uint8) <= y.(uint8)
		case uint16:
			return x.(uint16) <= y.(uint16)
		case uint32:
			return x.(uint32) <= y.(uint32)
		case uint64:
			return x.(uint64) <= y.(uint64)
		case uintptr:
			return x.(uintptr) <= y.(uintptr)
		case float32:
			return x.(float32) <= y.(float32)
		case float64:
			return x.(float64) <= y.(float64)
		case string:
			return x.(string) <= y.(string)
		}

	case token.EQL:
		return eqnil(t, x, y)

	case token.NEQ:
		return !eqnil(t, x, y)

	case token.GTR:
		switch x.(type) {
		case int:
			return x.(int) > y.(int)
		case int8:
			return x.(int8) > y.(int8)
		case int16:
			return x.(int16) > y.(int16)
		case int32:
			return x.(int32) > y.(int32)
		case int64:
			return x.(int64) > y.(int64)
		case uint:
			return x.(uint) > y.(uint)
		case uint8:
			return x.(uint8) > y.(uint8)
		case uint16:
			return x.(uint16) > y.(uint16)
		case uint32:
			return x.(uint32) > y.(uint32)
		case uint64:
			return x.(uint64) > y.(uint64)
		case uintptr:
			return x.(uintptr) > y.(uintptr)
		case float32:
			return x.(float32) > y.(float32)
		case float64:
			return x.(float64) > y.(float64)
		case string:
			return x.(string) > y.(string)
		}

	case token.GEQ:
		switch x.(type) {
		case int:
			return x.(int) >= y.(int)
		case int8:
			return x.(int8) >= y.(int8)
		case int16:
			return x.(int16) >= y.(int16)
		case int32:
			return x.(int32) >= y.(int32)
		case int64:
			return x.(int64) >= y.(int64)
		case uint:
			return x.(uint) >= y.(uint)
		case uint8:
			return x.(uint8) >= y.(uint8)
		case uint16:
			return x.(uint16) >= y.(uint16)
		case uint32:
			return x.(uint32) >= y.(uint32)
		case uint64:
			return x.(uint64) >= y.(uint64)
		case uintptr:
			return x.(uintptr) >= y.(uintptr)
		case float32:
			return x.(float32) >= y.(float32)
		case float64:
			return x.(float64) >= y.(float64)
		case string:
			return x.(string) >= y.(string)
		}
	}
	panic(fmt.Sprintf("invalid binary op: %T %s %T", x, op, y))
}

// eqnil returns the comparison x == y using the equivalence relation
// appropriate for type t.
// If t is a reference type, at most one of x or y may be a nil value
// of that type.
func eqnil(t types.Type, x, y value) bool {
	switch t.Underlying().(type) {
	case *types.Map, *types.Signature, *types.Slice:
		// Since these types don't support comparison,
		// one of the operands must be a literal nil.
		switch x := x.(type) {
		case *hashmap:
			return (x != nil) == (y.(*hashmap) != nil)
		case map[value]value:
			return (x != nil) == (y.(map[value]value) != nil)
		case *ssa.Function:
			switch y := y.(type) {
			case *ssa.Function:
				return (x != nil) == (y != nil)
			case *closure:
				return true
			}
		case *closure:
			return (x != nil) == (y.(*ssa.Function) != nil)
		case []value:
			return (x != nil) == (y.([]value) != nil)
		}
		panic(fmt.Sprintf("eqnil(%s): illegal dynamic type: %T", t, x))
	}

	return equals(t, x, y)
}

func unop(instr *ssa.UnOp, x value) value {
	switch instr.Op {
	case token.ARROW: // receive
		v, ok := <-x.(chan value)
		if !ok {
			v = zero(instr.X.Type().Underlying().(*types.Chan).Elem())
		}
		if instr.CommaOk {
			v = tuple{v, ok}
		}
		return v
	case token.SUB:
		switch x := x.(type) {
		case int:
			return -x
		case int8:
			return -x
		case int16:
			return -x
		case int32:
			return -x
		case int64:
			return -x
		case uint:
			return -x
		case uint8:
			return -x
		case uint16:
			return -x
		case uint32:
			return -x
		case uint64:
			return -x
		case uintptr:
			return -x
		case float32:
			return -x
		case float64:
			return -x
		case complex64:
			return -x
		case complex128:
			return -x
		}
	case token.MUL:
		return load(typeparams.MustDeref(instr.X.Type()), x.(*value))
	case token.NOT:
		return !x.(bool)
	case token.XOR:
		switch x := x.(type) {
		case int:
			return ^x
		case int8:
			return ^x
		case int16:
			return ^x
		case int32:
			return ^x
		case int64:
			return ^x
		case uint:
			return ^x
		case uint8:
			return ^x
		case uint16:
			return ^x
		case uint32:
			return ^x
		case uint64:
			return ^x
		case uintptr:
			return ^x
		}
	}
	panic(fmt.Sprintf("invalid unary op %s %T", instr.Op, x))
}

// typeAssert checks whether dynamic type of itf is instr.AssertedType.
// It returns the extracted value on success, and panics on failure,
// unless instr.CommaOk, in which case it always returns a "value,ok" tuple.
func typeAssert(instr *ssa.TypeAssert, itf iface) value {
	var v value
	err := ""
	if itf.t == nil {
		err = fmt.Sprintf("interface conversion: interface is nil, not %s", instr.AssertedType)

	} else if idst, ok := instr.AssertedType.Underlying().(*types.Interface); ok {
		v = itf
		err = checkInterface(idst, itf)

	} else if types.Identical(itf.t, instr.AssertedType) {
		v = itf.v // extract value

	} else {
		err = fmt.Sprintf("interface conversion: interface is %s, not %s", itf.t, instr.AssertedType)
	}
	// Note: if instr.Underlying==true ever becomes reachable from interp check that
	// types.Identical(itf.t.Underlying(), instr.AssertedType)

	if err != "" {
		if !instr.CommaOk {
			panic(err)
		}
		return tuple{zero(instr.AssertedType), false}
	}
	if instr.CommaOk {
		return tuple{v, true}
	}
	return v
}

// This variable is no longer used but remains to prevent build breakage.
var CapturedOutput *bytes.Buffer

// callBuiltin interprets a call to builtin fn with arguments args,
// returning its result.
func callBuiltin(caller *frame, fn *ssa.Builtin, args []value) value {
	switch fn.Name() {
	case "append":
		if len(args) == 1 {
			return args[0]
		}
		if s, ok := args[1].(string); ok {
			// append([]byte, ...string) []byte
			arg0 := args[0].([]value)
			for i := 0; i < len(s); i++ {
				arg0 = append(arg0, s[i])
			}
			return arg0
		}
		// append([]T, ...[]T) []T
		return append(args[0].([]value), args[1].([]value)...)

	case "copy": // copy([]T, []T) int or copy([]byte, string) int
		src := args[1]
		if _, ok := src.(string); ok {
			params := fn.Type().(*types.Signature).Params()
			src = conv(params.At(0).Type(), params.At(1).Type(), src)
		}
		return copy(args[0].([]value), src.([]value))

	case "close": // close(chan T)
		close(args[0].(chan value))
		return nil

	case "delete": // delete(map[K]value, K)
		switch m := args[0].(type) {
		case map[value]value:
			delete(m, args[1])
		case *hashmap:
			m.delete(args[1].(hashable))
		default:
			panic(fmt.Sprintf("illegal map type: %T", m))
		}
		return nil

	case "print", "println": // print(any, ...)
		ln := fn.Name() == "println"
		var buf bytes.Buffer
		for i, arg := range args {
			if i > 0 && ln {
				buf.WriteRune(' ')
			}
			buf.WriteString(toString(arg))
		}
		if ln {
			buf.WriteRune('\n')
		}
		os.Stderr.Write(buf.Bytes())
		return nil

	case "len":
		switch x := args[0].(type) {
		case string:
			return len(x)
		case array:
			return len(x)
		case *value:
			return len((*x).(array))
		case []value:
			return len(x)
		case map[value]value:
			return len(x)
		case *hashmap:
			return x.len()
		case chan value:
			return len(x)
		default:
			panic(fmt.Sprintf("len: illegal operand: %T", x))
		}

	case "cap":
		switch x := args[0].(type) {
		case array:
			return cap(x)
		case *value:
			return cap((*x).(array))
		case []value:
			return cap(x)
		case chan value:
			return cap(x)
		default:
			panic(fmt.Sprintf("cap: illegal operand: %T", x))
		}

	case "min":
		return foldLeft(min, args)
	case "max":
		return foldLeft(max, args)

	case "real":
		switch c := args[0].(type) {
		case complex64:
			return real(c)
		case complex128:
			return real(c)
		default:
			panic(fmt.Sprintf("real: illegal operand: %T", c))
		}

	case "imag":
		switch c := args[0].(type) {
		case complex64:
			return imag(c)
		case complex128:
			return imag(c)
		default:
			panic(fmt.Sprintf("imag: illegal operand: %T", c))
		}

	case "complex":
		switch f := args[0].(type) {
		case float32:
			return complex(f, args[1].(float32))
		case float64:
			return complex(f, args[1].(float64))
		default:
			panic(fmt.Sprintf("complex: illegal operand: %T", f))
		}

	case "panic":
		// ssa.Panic handles most cases; this is only for "go
		// panic" or "defer panic".
		panic(targetPanic{args[0]})

	case "recover":
		return doRecover(caller)

	case "ssa:wrapnilchk":
		recv := args[0]
		if recv.(*value) == nil {
			recvType := args[1]
			methodName := args[2]
			panic(fmt.Sprintf("value method (%s).%s called using nil *%s pointer",
				recvType, methodName, recvType))
		}
		return recv

	case "ssa:deferstack":
		return &caller.defers
	}

	panic("unknown built-in: " + fn.Name())
}

func rangeIter(x value) iter {
	switch x := x.(type) {
	case map[value]value:
		return &mapIter{iter: reflect.ValueOf(x).MapRange()}
	case *hashmap:
		return &hashmapIter{iter: reflect.ValueOf(x.entries()).MapRange()}
	case string:
		return &stringIter{Reader: strings.NewReader(x)}
	}
	panic(fmt.Sprintf("cannot range over %T", x))
}

// widen widens a basic typed value x to the widest type of its
// category, one of:
//
//	bool, int64, uint64, float64, complex128, string.
//
// This is inefficient but reduces the size of the cross-product of
// cases we have to consider.
func widen(x value) value {
	switch y := x.(type) {
	case bool, int64, uint64, float64, complex128, string, unsafe.Pointer:
		return x
	case int:
		return int64(y)
	case int8:
		return int64(y)
	case int16:
		return int64(y)
	case int32:
		return int64(y)
	case uint:
		return uint64(y)
	case uint8:
		return uint64(y)
	case uint16:
		return uint64(y)
	case uint32:
		return uint64(y)
	case uintptr:
		return uint64(y)
	case float32:
		return float64(y)
	case complex64:
		return complex128(y)
	}
	panic(fmt.Sprintf("cannot widen %T", x))
}

// conv converts the value x of type t_src to type t_dst and returns
// the result.
// Possible cases are described with the ssa.Convert operator.
func conv(t_dst, t_src types.Type, x value) value {
	ut_src := t_src.Underlying()
	ut_dst := t_dst.Underlying()

	// Destination type is not an "untyped" type.
	if b, ok := ut_dst.(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
		panic("oops: conversion to 'untyped' type: " + b.String())
	}

	// Nor is it an interface type.
	if _, ok := ut_dst.(*types.Interface); ok {
		if _, ok := ut_src.(*types.Interface); ok {
			panic("oops: Convert should be ChangeInterface")
		} else {
			panic("oops: Convert should be MakeInterface")
		}
	}

	// Remaining conversions:
	//    + untyped string/number/bool constant to a specific
	//      representation.
	//    + conversions between non-complex numeric types.
	//    + conversions between complex numeric types.
	//    + integer/[]byte/[]rune -> string.
	//    + string -> []byte/[]rune.
	//
	// All are treated the same: first we extract the value to the
	// widest representation (int64, uint64, float64, complex128,
	// or string), then we convert it to the desired type.

	switch ut_src := ut_src.(type) {
	case *types.Pointer:
		switch ut_dst := ut_dst.(type) {
		case *types.Basic:
			// *value to unsafe.Pointer?
			if ut_dst.Kind() == types.UnsafePointer {
				return unsafe.Pointer(x.(*value))
			}
		}

	case *types.Slice:
		// []byte or []rune -> string
		switch ut_src.Elem().Underlying().(*types.Basic).Kind() {
		case types.Byte:
			x := x.([]value)
			b := make([]byte, 0, len(x))
			for i := range x {
				b = append(b, x[i].(byte))
			}
			return string(b)

		case types.Rune:
			x := x.([]value)
			r := make([]rune, 0, len(x))
			for i := range x {
				r = append(r, x[i].(rune))
			}
			return string(r)
		}

	case *types.Basic:
		x = widen(x)

		// integer -> string?
		if ut_src.Info()&types.IsInteger != 0 {
			if ut_dst, ok := ut_dst.(*types.Basic); ok && ut_dst.Kind() == types.String {
				return fmt.Sprintf("%c", x)
			}
		}

		// string -> []rune, []byte or string?
		if s, ok := x.(string); ok {
			switch ut_dst := ut_dst.(type) {
			case *types.Slice:
				var res []value
				switch ut_dst.Elem().Underlying().(*types.Basic).Kind() {
				case types.Rune:
					for _, r := range []rune(s) {
						res = append(res, r)
					}
					return res
				case types.Byte:
					for _, b := range []byte(s) {
						res = append(res, b)
					}
					return res
				}
			case *types.Basic:
				if ut_dst.Kind() == types.String {
					return x.(string)
				}
			}
			break // fail: no other conversions for string
		}

		// unsafe.Pointer -> *value
		if ut_src.Kind() == types.UnsafePointer {
			// TODO(adonovan): this is wrong and cannot
			// really be fixed with the current design.
			//
			// return (*value)(x.(unsafe.Pointer))
			// creates a new pointer of a different
			// type but the underlying interface value
			// knows its "true" type and so cannot be
			// meaningfully used through the new pointer.
			//
			// To make this work, the interpreter needs to
			// simulate the memory layout of a real
			// compiled implementation.
			//
			// To at least preserve type-safety, we'll
			// just return the zero value of the
			// destination type.
			return zero(t_dst)
		}

		// Conversions between complex numeric types?
		if ut_src.Info()&types.IsComplex != 0 {
			switch ut_dst.(*types.Basic).Kind() {
			case types.Complex64:
				return complex64(x.(complex128))
			case types.Complex128:
				return x.(complex128)
			}
			break // fail: no other conversions for complex
		}

		// Conversions between non-complex numeric types?
		if ut_src.Info()&types.IsNumeric != 0 {
			kind := ut_dst.(*types.Basic).Kind()
			switch x := x.(type) {
			case int64: // signed integer -> numeric?
				switch kind {
				case types.Int:
					return int(x)
				case types.Int8:
					return int8(x)
				case types.Int16:
					return int16(x)
				case types.Int32:
					return int32(x)
				case types.Int64:
					return int64(x)
				case types.Uint:
					return uint(x)
				case types.Uint8:
					return uint8(x)
				case types.Uint16:
					return uint16(x)
				case types.Uint32:
					return uint32(x)
				case types.Uint64:
					return uint64(x)
				case types.Uintptr:
					return uintptr(x)
				case types.Float32:
					return float32(x)
				case types.Float64:
					return float64(x)
				}

			case uint64: // unsigned integer -> numeric?
				switch kind {
				case types.Int:
					return int(x)
				case types.Int8:
					return int8(x)
				case types.Int16:
					return int16(x)
				case types.Int32:
					return int32(x)
				case types.Int64:
					return int64(x)
				case types.Uint:
					return uint(x)
				case types.Uint8:
					return uint8(x)
				case types.Uint16:
					return uint16(x)
				case types.Uint32:
					return uint32(x)
				case types.Uint64:
					return uint64(x)
				case types.Uintptr:
					return uintptr(x)
				case types.Float32:
					return float32(x)
				case types.Float64:
					return float64(x)
				}

			case float64: // floating point -> numeric?
				switch kind {
				case types.Int:
					return int(x)
				case types.Int8:
					return int8(x)
				case types.Int16:
					return int16(x)
				case types.Int32:
					return int32(x)
				case types.Int64:
					return int64(x)
				case types.Uint:
					return uint(x)
				case types.Uint8:
					return uint8(x)
				case types.Uint16:
					return uint16(x)
				case types.Uint32:
					return uint32(x)
				case types.Uint64:
					return uint64(x)
				case types.Uintptr:
					return uintptr(x)
				case types.Float32:
					return float32(x)
				case types.Float64:
					return float64(x)
				}
			}
		}
	}

	panic(fmt.Sprintf("unsupported conversion: %s  -> %s, dynamic type %T", t_src, t_dst, x))
}

// sliceToArrayPointer converts the value x of type slice to type t_dst
// a pointer to array and returns the result.
func sliceToArrayPointer(t_dst, t_src types.Type, x value) value {
	if _, ok := t_src.Underlying().(*types.Slice); ok {
		if ptr, ok := t_dst.Underlying().(*types.Pointer); ok {
			if arr, ok := ptr.Elem().Underlying().(*types.Array); ok {
				x := x.([]value)
				if arr.Len() > int64(len(x)) {
					panic("array length is greater than slice length")
				}
				if x == nil {
					return zero(t_dst)
				}
				v := value(array(x[:arr.Len()]))
				return &v
			}
		}
	}

	panic(fmt.Sprintf("unsupported conversion: %s  -> %s, dynamic type %T", t_src, t_dst, x))
}

// checkInterface checks that the method set of x implements the
// interface itype.
// On success it returns "", on failure, an error message.
func checkInterface(itype *types.Interface, x iface) string {
	if meth, _ := types.MissingMethod(x.t, itype, true); meth != nil {
		return fmt.Sprintf("interface conversion: %v is not %v: missing method %s",
			x.t, itype, meth.Name())
	}
	return "" // ok
}

func foldLeft(op func(value, value) value, args []value) value {
	x := args[0]
	for _, arg := range args[1:] {
		x = op(x, arg)
	}
	return x
}

func min(x, y value) value {
	switch x := x.(type) {
	case float32:
		return fmin(x, y.(float32))
	case float64:
		return fmin(x, y.(float64))
	}

	// return (y < x) ? y : x
	if binop(token.LSS, nil, y, x).(bool) {
		return y
	}
	return x
}

func max(x, y value) value {
	switch x := x.(type) {
	case float32:
		return fmax(x, y.(float32))
	case float64:
		return fmax(x, y.(float64))
	}

	// return (y > x) ? y : x
	if binop(token.GTR, nil, y, x).(bool) {
		return y
	}
	return x
}

// copied from $GOROOT/src/runtime/minmax.go

type floaty interface{ ~float32 | ~float64 }

func fmin[F floaty](x, y F) F {
	if y != y || y < x {
		return y
	}
	if x != x || x < y || x != 0 {
		return x
	}
	// x and y are both ±0
	// if either is -0, return -0; else return +0
	return forbits(x, y)
}

func fmax[F floaty](x, y F) F {
	if y != y || y > x {
		return y
	}
	if x != x || x > y || x != 0 {
		return x
	}
	// x and y are both ±0
	// if both are -0, return -0; else return +0
	return fandbits(x, y)
}

func forbits[F floaty](x, y F) F {
	switch unsafe.Sizeof(x) {
	case 4:
		*(*uint32)(unsafe.Pointer(&x)) |= *(*uint32)(unsafe.Pointer(&y))
	case 8:
		*(*uint64)(unsafe.Pointer(&x)) |= *(*uint64)(unsafe.Pointer(&y))
	}
	return x
}

func fandbits[F floaty](x, y F) F {
	switch unsafe.Sizeof(x) {
	case 4:
		*(*uint32)(unsafe.Pointer(&x)) &= *(*uint32)(unsafe.Pointer(&y))
	case 8:
		*(*uint64)(unsafe.Pointer(&x)) &= *(*uint64)(unsafe.Pointer(&y))
	}
	return x
}


================================================
FILE: go/ssa/interp/rangefunc_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp_test

import (
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func TestIssue69298(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)

	goroot := makeGoroot(t)
	run(t, filepath.Join("testdata", "fixedbugs", "issue69298.go"), goroot)
}

func TestRangeFunc(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)

	goroot := makeGoroot(t)
	out := run(t, filepath.Join("testdata", "rangefunc.go"), goroot)

	// Check the output of the tests.
	const (
		RERR_DONE      = "Saw expected panic: yield function called after range loop exit"
		RERR_MISSING   = "Saw expected panic: iterator call did not preserve panic"
		RERR_EXHAUSTED = RERR_DONE // ssa does not distinguish. Same message as RERR_DONE.

		CERR_DONE      = "Saw expected panic: checked rangefunc error: loop iteration after body done"
		CERR_EXHAUSTED = "Saw expected panic: checked rangefunc error: loop iteration after iterator exit"
		CERR_MISSING   = "Saw expected panic: checked rangefunc error: loop iterator swallowed panic"

		panickyIterMsg = "Saw expected panic: Panicky iterator panicking"
	)
	expected := map[string][]string{
		// rangefunc.go
		"TestCheck":                           {"i = 45", CERR_DONE},
		"TestCooperativeBadOfSliceIndex":      {RERR_EXHAUSTED, "i = 36"},
		"TestCooperativeBadOfSliceIndexCheck": {CERR_EXHAUSTED, "i = 36"},
		"TestTrickyIterAll":                   {"i = 36", RERR_EXHAUSTED},
		"TestTrickyIterOne":                   {"i = 1", RERR_EXHAUSTED},
		"TestTrickyIterZero":                  {"i = 0", RERR_EXHAUSTED},
		"TestTrickyIterZeroCheck":             {"i = 0", CERR_EXHAUSTED},
		"TestTrickyIterEcho": {
			"first loop i=0",
			"first loop i=1",
			"first loop i=3",
			"first loop i=6",
			"i = 10",
			"second loop i=0",
			RERR_EXHAUSTED,
			"end i=0",
		},
		"TestTrickyIterEcho2": {
			"k=0,x=1,i=0",
			"k=0,x=2,i=1",
			"k=0,x=3,i=3",
			"k=0,x=4,i=6",
			"i = 10",
			"k=1,x=1,i=0",
			RERR_EXHAUSTED,
			"end i=1",
		},
		"TestBreak1":                {"[1 2 -1 1 2 -2 1 2 -3]"},
		"TestBreak2":                {"[1 2 -1 1 2 -2 1 2 -3]"},
		"TestContinue":              {"[-1 1 2 -2 1 2 -3 1 2 -4]"},
		"TestBreak3":                {"[100 10 2 4 200 10 2 4 20 2 4 300 10 2 4 20 2 4 30]"},
		"TestBreak1BadA":            {"[1 2 -1 1 2 -2 1 2 -3]", RERR_DONE},
		"TestBreak1BadB":            {"[1 2]", RERR_DONE},
		"TestMultiCont0":            {"[1000 10 2 4 2000]"},
		"TestMultiCont1":            {"[1000 10 2 4]", RERR_DONE},
		"TestMultiCont2":            {"[1000 10 2 4]", RERR_DONE},
		"TestMultiCont3":            {"[1000 10 2 4]", RERR_DONE},
		"TestMultiBreak0":           {"[1000 10 2 4]", RERR_DONE},
		"TestMultiBreak1":           {"[1000 10 2 4]", RERR_DONE},
		"TestMultiBreak2":           {"[1000 10 2 4]", RERR_DONE},
		"TestMultiBreak3":           {"[1000 10 2 4]", RERR_DONE},
		"TestPanickyIterator1":      {panickyIterMsg},
		"TestPanickyIterator1Check": {panickyIterMsg},
		"TestPanickyIterator2":      {RERR_MISSING},
		"TestPanickyIterator2Check": {CERR_MISSING},
		"TestPanickyIterator3":      {"[100 10 1 2 200 10 1 2]"},
		"TestPanickyIterator3Check": {"[100 10 1 2 200 10 1 2]"},
		"TestPanickyIterator4":      {RERR_MISSING},
		"TestPanickyIterator4Check": {CERR_MISSING},
		"TestVeryBad1":              {"[1 10]"},
		"TestVeryBad2":              {"[1 10]"},
		"TestVeryBadCheck":          {"[1 10]"},
		"TestOk":                    {"[1 10]"},
		"TestBreak1BadDefer":        {RERR_DONE, "[1 2 -1 1 2 -2 1 2 -3 -30 -20 -10]"},
		"TestReturns":               {"[-1 1 2 -10]", "[-1 1 2 -10]", RERR_DONE, "[-1 1 2 -10]", RERR_DONE},
		"TestGotoA":                 {"testGotoA1[-1 1 2 -2 1 2 -3 1 2 -4 -30 -20 -10]", "testGotoA2[-1 1 2 -2 1 2 -3 1 2 -4 -30 -20 -10]", RERR_DONE, "testGotoA3[-1 1 2 -10]", RERR_DONE},
		"TestGotoB":                 {"testGotoB1[-1 1 2 999 -10]", "testGotoB2[-1 1 2 -10]", RERR_DONE, "testGotoB3[-1 1 2 -10]", RERR_DONE},
		"TestPanicReturns": {
			"Got expected 'f return'",
			"Got expected 'g return'",
			"Got expected 'h return'",
			"Got expected 'k return'",
			"Got expected 'j return'",
			"Got expected 'm return'",
			"Got expected 'n return and n closure return'",
		},
	}
	got := make(map[string][]string)
	for ln := range strings.SplitSeq(out, "\n") {
		if ind := strings.Index(ln, " \t "); ind >= 0 {
			n, m := ln[:ind], ln[ind+3:]
			got[n] = append(got[n], m)
		}
	}
	for n, es := range expected {
		if gs := got[n]; !reflect.DeepEqual(es, gs) {
			t.Errorf("Output of test %s did not match expected output %v. got %v", n, es, gs)
		}
	}
	for n, gs := range got {
		if expected[n] == nil {
			t.Errorf("No expected output for test %s. got %v", n, gs)
		}
	}
}


================================================
FILE: go/ssa/interp/reflect.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp

// Emulated "reflect" package.
//
// We completely replace the built-in "reflect" package.
// The only thing clients can depend upon are that reflect.Type is an
// interface and reflect.Value is an (opaque) struct.

import (
	"fmt"
	"go/token"
	"go/types"
	"reflect"
	"unsafe"

	"golang.org/x/tools/go/ssa"
)

type opaqueType struct {
	types.Type
	name string
}

func (t *opaqueType) String() string { return t.name }

// A bogus "reflect" type-checker package.  Shared across interpreters.
var reflectTypesPackage = types.NewPackage("reflect", "reflect")

// rtype is the concrete type the interpreter uses to implement the
// reflect.Type interface.
//
// type rtype <opaque>
var rtypeType = makeNamedType("rtype", &opaqueType{nil, "rtype"})

// error is an (interpreted) named type whose underlying type is string.
// The interpreter uses it for all implementations of the built-in error
// interface that it creates.
// We put it in the "reflect" package for expedience.
//
// type error string
var errorType = makeNamedType("error", &opaqueType{nil, "error"})

func makeNamedType(name string, underlying types.Type) *types.Named {
	obj := types.NewTypeName(token.NoPos, reflectTypesPackage, name, nil)
	return types.NewNamed(obj, underlying, nil)
}

func makeReflectValue(t types.Type, v value) value {
	return structure{rtype{t}, v}
}

// Given a reflect.Value, returns its rtype.
func rV2T(v value) rtype {
	return v.(structure)[0].(rtype)
}

// Given a reflect.Value, returns the underlying interpreter value.
func rV2V(v value) value {
	return v.(structure)[1]
}

// makeReflectType boxes up an rtype in a reflect.Type interface.
func makeReflectType(rt rtype) value {
	return iface{rtypeType, rt}
}

func ext۰reflect۰rtype۰Bits(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) int
	rt := args[0].(rtype).t
	basic, ok := rt.Underlying().(*types.Basic)
	if !ok {
		panic(fmt.Sprintf("reflect.Type.Bits(%T): non-basic type", rt))
	}
	return int(fr.i.sizes.Sizeof(basic)) * 8
}

func ext۰reflect۰rtype۰Elem(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) reflect.Type
	return makeReflectType(rtype{args[0].(rtype).t.Underlying().(interface {
		Elem() types.Type
	}).Elem()})
}

func ext۰reflect۰rtype۰Field(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype, i int) reflect.StructField
	st := args[0].(rtype).t.Underlying().(*types.Struct)
	i := args[1].(int)
	f := st.Field(i)
	return structure{
		f.Name(),
		f.Pkg().Path(),
		makeReflectType(rtype{f.Type()}),
		st.Tag(i),
		0,         // TODO(adonovan): offset
		[]value{}, // TODO(adonovan): indices
		f.Anonymous(),
	}
}

func ext۰reflect۰rtype۰In(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype, i int) int
	i := args[1].(int)
	return makeReflectType(rtype{args[0].(rtype).t.(*types.Signature).Params().At(i).Type()})
}

func ext۰reflect۰rtype۰Kind(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) uint
	return uint(reflectKind(args[0].(rtype).t))
}

func ext۰reflect۰rtype۰NumField(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) int
	return args[0].(rtype).t.Underlying().(*types.Struct).NumFields()
}

func ext۰reflect۰rtype۰NumIn(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) int
	return args[0].(rtype).t.Underlying().(*types.Signature).Params().Len()
}

func ext۰reflect۰rtype۰NumMethod(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) int
	return fr.i.prog.MethodSets.MethodSet(args[0].(rtype).t).Len()
}

func ext۰reflect۰rtype۰NumOut(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) int
	return args[0].(rtype).t.Underlying().(*types.Signature).Results().Len()
}

func ext۰reflect۰rtype۰Out(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype, i int) int
	i := args[1].(int)
	return makeReflectType(rtype{args[0].(rtype).t.Underlying().(*types.Signature).Results().At(i).Type()})
}

func ext۰reflect۰rtype۰Size(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) uintptr
	return uintptr(fr.i.sizes.Sizeof(args[0].(rtype).t))
}

func ext۰reflect۰rtype۰String(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) string
	return args[0].(rtype).t.String()
}

func ext۰reflect۰New(fr *frame, args []value) value {
	// Signature: func (t reflect.Type) reflect.Value
	t := args[0].(iface).v.(rtype).t
	alloc := zero(t)
	return makeReflectValue(types.NewPointer(t), &alloc)
}

func ext۰reflect۰SliceOf(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) Type
	return makeReflectType(rtype{types.NewSlice(args[0].(iface).v.(rtype).t)})
}

func ext۰reflect۰TypeOf(fr *frame, args []value) value {
	// Signature: func (t reflect.rtype) Type
	return makeReflectType(rtype{args[0].(iface).t})
}

func ext۰reflect۰ValueOf(fr *frame, args []value) value {
	// Signature: func (interface{}) reflect.Value
	itf := args[0].(iface)
	return makeReflectValue(itf.t, itf.v)
}

func ext۰reflect۰Zero(fr *frame, args []value) value {
	// Signature: func (t reflect.Type) reflect.Value
	t := args[0].(iface).v.(rtype).t
	return makeReflectValue(t, zero(t))
}

func reflectKind(t types.Type) reflect.Kind {
	switch t := t.(type) {
	case *types.Named, *types.Alias:
		return reflectKind(t.Underlying())
	case *types.Basic:
		switch t.Kind() {
		case types.Bool:
			return reflect.Bool
		case types.Int:
			return reflect.Int
		case types.Int8:
			return reflect.Int8
		case types.Int16:
			return reflect.Int16
		case types.Int32:
			return reflect.Int32
		case types.Int64:
			return reflect.Int64
		case types.Uint:
			return reflect.Uint
		case types.Uint8:
			return reflect.Uint8
		case types.Uint16:
			return reflect.Uint16
		case types.Uint32:
			return reflect.Uint32
		case types.Uint64:
			return reflect.Uint64
		case types.Uintptr:
			return reflect.Uintptr
		case types.Float32:
			return reflect.Float32
		case types.Float64:
			return reflect.Float64
		case types.Complex64:
			return reflect.Complex64
		case types.Complex128:
			return reflect.Complex128
		case types.String:
			return reflect.String
		case types.UnsafePointer:
			return reflect.UnsafePointer
		}
	case *types.Array:
		return reflect.Array
	case *types.Chan:
		return reflect.Chan
	case *types.Signature:
		return reflect.Func
	case *types.Interface:
		return reflect.Interface
	case *types.Map:
		return reflect.Map
	case *types.Pointer:
		return reflect.Pointer
	case *types.Slice:
		return reflect.Slice
	case *types.Struct:
		return reflect.Struct
	}
	panic(fmt.Sprint("unexpected type: ", t))
}

func ext۰reflect۰Value۰Kind(fr *frame, args []value) value {
	// Signature: func (reflect.Value) uint
	return uint(reflectKind(rV2T(args[0]).t))
}

func ext۰reflect۰Value۰String(fr *frame, args []value) value {
	// Signature: func (reflect.Value) string
	return toString(rV2V(args[0]))
}

func ext۰reflect۰Value۰Type(fr *frame, args []value) value {
	// Signature: func (reflect.Value) reflect.Type
	return makeReflectType(rV2T(args[0]))
}

func ext۰reflect۰Value۰Uint(fr *frame, args []value) value {
	// Signature: func (reflect.Value) uint64
	switch v := rV2V(args[0]).(type) {
	case uint:
		return uint64(v)
	case uint8:
		return uint64(v)
	case uint16:
		return uint64(v)
	case uint32:
		return uint64(v)
	case uint64:
		return uint64(v)
	case uintptr:
		return uint64(v)
	}
	panic("reflect.Value.Uint")
}

func ext۰reflect۰Value۰Len(fr *frame, args []value) value {
	// Signature: func (reflect.Value) int
	switch v := rV2V(args[0]).(type) {
	case string:
		return len(v)
	case array:
		return len(v)
	case chan value:
		return cap(v)
	case []value:
		return len(v)
	case *hashmap:
		return v.len()
	case map[value]value:
		return len(v)
	default:
		panic(fmt.Sprintf("reflect.(Value).Len(%v)", v))
	}
}

func ext۰reflect۰Value۰MapIndex(fr *frame, args []value) value {
	// Signature: func (reflect.Value) Value
	tValue := rV2T(args[0]).t.Underlying().(*types.Map).Key()
	k := rV2V(args[1])
	switch m := rV2V(args[0]).(type) {
	case map[value]value:
		if v, ok := m[k]; ok {
			return makeReflectValue(tValue, v)
		}

	case *hashmap:
		if v := m.lookup(k.(hashable)); v != nil {
			return makeReflectValue(tValue, v)
		}

	default:
		panic(fmt.Sprintf("(reflect.Value).MapIndex(%T, %T)", m, k))
	}
	return makeReflectValue(nil, nil)
}

func ext۰reflect۰Value۰MapKeys(fr *frame, args []value) value {
	// Signature: func (reflect.Value) []Value
	var keys []value
	tKey := rV2T(args[0]).t.Underlying().(*types.Map).Key()
	switch v := rV2V(args[0]).(type) {
	case map[value]value:
		for k := range v {
			keys = append(keys, makeReflectValue(tKey, k))
		}

	case *hashmap:
		for _, e := range v.entries() {
			for ; e != nil; e = e.next {
				keys = append(keys, makeReflectValue(tKey, e.key))
			}
		}

	default:
		panic(fmt.Sprintf("(reflect.Value).MapKeys(%T)", v))
	}
	return keys
}

func ext۰reflect۰Value۰NumField(fr *frame, args []value) value {
	// Signature: func (reflect.Value) int
	return len(rV2V(args[0]).(structure))
}

func ext۰reflect۰Value۰NumMethod(fr *frame, args []value) value {
	// Signature: func (reflect.Value) int
	return fr.i.prog.MethodSets.MethodSet(rV2T(args[0]).t).Len()
}

func ext۰reflect۰Value۰Pointer(fr *frame, args []value) value {
	// Signature: func (v reflect.Value) uintptr
	switch v := rV2V(args[0]).(type) {
	case *value:
		return uintptr(unsafe.Pointer(v))
	case chan value:
		return reflect.ValueOf(v).Pointer()
	case []value:
		return reflect.ValueOf(v).Pointer()
	case *hashmap:
		return reflect.ValueOf(v.entries()).Pointer()
	case map[value]value:
		return reflect.ValueOf(v).Pointer()
	case *ssa.Function:
		return uintptr(unsafe.Pointer(v))
	case *closure:
		return uintptr(unsafe.Pointer(v))
	default:
		panic(fmt.Sprintf("reflect.(Value).Pointer(%T)", v))
	}
}

func ext۰reflect۰Value۰Index(fr *frame, args []value) value {
	// Signature: func (v reflect.Value, i int) Value
	i := args[1].(int)
	t := rV2T(args[0]).t.Underlying()
	switch v := rV2V(args[0]).(type) {
	case array:
		return makeReflectValue(t.(*types.Array).Elem(), v[i])
	case []value:
		return makeReflectValue(t.(*types.Slice).Elem(), v[i])
	default:
		panic(fmt.Sprintf("reflect.(Value).Index(%T)", v))
	}
}

func ext۰reflect۰Value۰Bool(fr *frame, args []value) value {
	// Signature: func (reflect.Value) bool
	return rV2V(args[0]).(bool)
}

func ext۰reflect۰Value۰CanAddr(fr *frame, args []value) value {
	// Signature: func (v reflect.Value) bool
	// Always false for our representation.
	return false
}

func ext۰reflect۰Value۰CanInterface(fr *frame, args []value) value {
	// Signature: func (v reflect.Value) bool
	// Always true for our representation.
	return true
}

func ext۰reflect۰Value۰Elem(fr *frame, args []value) value {
	// Signature: func (v reflect.Value) reflect.Value
	switch x := rV2V(args[0]).(type) {
	case iface:
		return makeReflectValue(x.t, x.v)
	case *value:
		var v value
		if x != nil {
			v = *x
		}
		return makeReflectValue(rV2T(args[0]).t.Underlying().(*types.Pointer).Elem(), v)
	default:
		panic(fmt.Sprintf("reflect.(Value).Elem(%T)", x))
	}
}

func ext۰reflect۰Value۰Field(fr *frame, args []value) value {
	// Signature: func (v reflect.Value, i int) reflect.Value
	v := args[0]
	i := args[1].(int)
	return makeReflectValue(rV2T(v).t.Underlying().(*types.Struct).Field(i).Type(), rV2V(v).(structure)[i])
}

func ext۰reflect۰Value۰Float(fr *frame, args []value) value {
	// Signature: func (reflect.Value) float64
	switch v := rV2V(args[0]).(type) {
	case float32:
		return float64(v)
	case float64:
		return float64(v)
	}
	panic("reflect.Value.Float")
}

func ext۰reflect۰Value۰Interface(fr *frame, args []value) value {
	// Signature: func (v reflect.Value) interface{}
	return ext۰reflect۰valueInterface(args)
}

func ext۰reflect۰Value۰Int(fr *frame, args []value) value {
	// Signature: func (reflect.Value) int64
	switch x := rV2V(args[0]).(type) {
	case int:
		return int64(x)
	case int8:
		return int64(x)
	case int16:
		return int64(x)
	case int32:
		return int64(x)
	case int64:
		return x
	default:
		panic(fmt.Sprintf("reflect.(Value).Int(%T)", x))
	}
}

func ext۰reflect۰Value۰IsNil(fr *frame, args []value) value {
	// Signature: func (reflect.Value) bool
	switch x := rV2V(args[0]).(type) {
	case *value:
		return x == nil
	case chan value:
		return x == nil
	case map[value]value:
		return x == nil
	case *hashmap:
		return x == nil
	case iface:
		return x.t == nil
	case []value:
		return x == nil
	case *ssa.Function:
		return x == nil
	case *ssa.Builtin:
		return x == nil
	case *closure:
		return x == nil
	default:
		panic(fmt.Sprintf("reflect.(Value).IsNil(%T)", x))
	}
}

func ext۰reflect۰Value۰IsValid(fr *frame, args []value) value {
	// Signature: func (reflect.Value) bool
	return rV2V(args[0]) != nil
}

func ext۰reflect۰Value۰Set(fr *frame, args []value) value {
	// TODO(adonovan): implement.
	return nil
}

func ext۰reflect۰valueInterface(args []value) value {
	// Signature: func (v reflect.Value, safe bool) interface{}
	v := args[0].(structure)
	return iface{rV2T(v).t, rV2V(v)}
}

func ext۰reflect۰error۰Error(fr *frame, args []value) value {
	return args[0]
}

// newMethod creates a new method of the specified name, package and receiver type.
func newMethod(pkg *ssa.Package, recvType types.Type, name string) *ssa.Function {
	// TODO(adonovan): fix: hack: currently the only part of Signature
	// that is needed is the "pointerness" of Recv.Type, and for
	// now, we'll set it to always be false since we're only
	// concerned with rtype.  Encapsulate this better.
	sig := types.NewSignatureType(types.NewParam(token.NoPos, nil, "recv", recvType), nil, nil, nil, nil, false)
	fn := pkg.Prog.NewFunction(name, sig, "fake reflect method")
	fn.Pkg = pkg
	return fn
}

func initReflect(i *interpreter) {
	i.reflectPackage = &ssa.Package{
		Prog:    i.prog,
		Pkg:     reflectTypesPackage,
		Members: make(map[string]ssa.Member),
	}

	// Clobber the type-checker's notion of reflect.Value's
	// underlying type so that it more closely matches the fake one
	// (at least in the number of fields---we lie about the type of
	// the rtype field).
	//
	// We must ensure that calls to (ssa.Value).Type() return the
	// fake type so that correct "shape" is used when allocating
	// variables, making zero values, loading, and storing.
	//
	// TODO(adonovan): obviously this is a hack.  We need a cleaner
	// way to fake the reflect package (almost---DeepEqual is fine).
	// One approach would be not to even load its source code, but
	// provide fake source files.  This would guarantee that no bad
	// information leaks into other packages.
	if r := i.prog.ImportedPackage("reflect"); r != nil {
		rV := r.Pkg.Scope().Lookup("Value").Type().(*types.Named)

		// delete bodies of the old methods
		mset := i.prog.MethodSets.MethodSet(rV)
		for method := range mset.Methods() {
			i.prog.MethodValue(method).Blocks = nil
		}

		tEface := types.NewInterface(nil, nil).Complete()
		rV.SetUnderlying(types.NewStruct([]*types.Var{
			types.NewField(token.NoPos, r.Pkg, "t", tEface, false), // a lie
			types.NewField(token.NoPos, r.Pkg, "v", tEface, false),
		}, nil))
	}

	i.rtypeMethods = methodSet{
		"Bits":      newMethod(i.reflectPackage, rtypeType, "Bits"),
		"Elem":      newMethod(i.reflectPackage, rtypeType, "Elem"),
		"Field":     newMethod(i.reflectPackage, rtypeType, "Field"),
		"In":        newMethod(i.reflectPackage, rtypeType, "In"),
		"Kind":      newMethod(i.reflectPackage, rtypeType, "Kind"),
		"NumField":  newMethod(i.reflectPackage, rtypeType, "NumField"),
		"NumIn":     newMethod(i.reflectPackage, rtypeType, "NumIn"),
		"NumMethod": newMethod(i.reflectPackage, rtypeType, "NumMethod"),
		"NumOut":    newMethod(i.reflectPackage, rtypeType, "NumOut"),
		"Out":       newMethod(i.reflectPackage, rtypeType, "Out"),
		"Size":      newMethod(i.reflectPackage, rtypeType, "Size"),
		"String":    newMethod(i.reflectPackage, rtypeType, "String"),
	}
	i.errorMethods = methodSet{
		"Error": newMethod(i.reflectPackage, errorType, "Error"),
	}
}


================================================
FILE: go/ssa/interp/testdata/boundmeth.go
================================================
// Tests of bound method closures.

package main

import (
	"errors"
	"fmt"
)

func assert(b bool) {
	if !b {
		panic("oops")
	}
}

type I int

func (i I) add(x int) int {
	return int(i) + x
}

func valueReceiver() {
	var three I = 3
	assert(three.add(5) == 8)
	var add3 func(int) int = three.add
	assert(add3(5) == 8)
}

type S struct{ x int }

func (s *S) incr() {
	s.x++
}

func (s *S) get() int {
	return s.x
}

func pointerReceiver() {
	ps := new(S)
	incr := ps.incr
	get := ps.get
	assert(get() == 0)
	incr()
	incr()
	incr()
	assert(get() == 3)
}

func addressibleValuePointerReceiver() {
	var s S
	incr := s.incr
	get := s.get
	assert(get() == 0)
	incr()
	incr()
	incr()
	assert(get() == 3)
}

type S2 struct {
	S
}

func promotedReceiver() {
	var s2 S2
	incr := s2.incr
	get := s2.get
	assert(get() == 0)
	incr()
	incr()
	incr()
	assert(get() == 3)
}

func anonStruct() {
	var s struct{ S }
	incr := s.incr
	get := s.get
	assert(get() == 0)
	incr()
	incr()
	incr()
	assert(get() == 3)
}

func typeCheck() {
	var i interface{}
	i = (*S).incr
	_ = i.(func(*S)) // type assertion: receiver type prepended to params

	var s S
	i = s.incr
	_ = i.(func()) // type assertion: receiver type disappears
}

type errString string

func (err errString) Error() string {
	return string(err)
}

// Regression test for a builder crash.
func regress1(x error) func() string {
	return x.Error
}

// Regression test for b/7269:
// taking the value of an interface method performs a nil check.
func nilInterfaceMethodValue() {
	err := errors.New("ok")
	f := err.Error
	if got := f(); got != "ok" {
		panic(got)
	}

	err = nil
	if got := f(); got != "ok" {
		panic(got)
	}

	defer func() {
		r := fmt.Sprint(recover())
		// runtime panic string varies across toolchains
		if r != "interface conversion: interface is nil, not error" &&
			r != "runtime error: invalid memory address or nil pointer dereference" &&
			r != "method value: interface is nil" {
			panic("want runtime panic from nil interface method value, got " + r)
		}
	}()
	f = err.Error // runtime panic: err is nil
	panic("unreachable")
}

func main() {
	valueReceiver()
	pointerReceiver()
	addressibleValuePointerReceiver()
	promotedReceiver()
	anonStruct()
	typeCheck()

	if e := regress1(errString("hi"))(); e != "hi" {
		panic(e)
	}

	nilInterfaceMethodValue()
}


================================================
FILE: go/ssa/interp/testdata/complit.go
================================================
package main

// Tests of composite literals.

import "fmt"

// Map literals.
// TODO(adonovan): we can no longer print maps
// until the interpreter supports (reflect.Value).MapRange.
func _() {
	type M map[int]int
	m1 := []*M{{1: 1}, &M{2: 2}}
	want := "map[1:1] map[2:2]"
	if got := fmt.Sprint(*m1[0], *m1[1]); got != want {
		panic(got)
	}
	m2 := []M{{1: 1}, M{2: 2}}
	if got := fmt.Sprint(m2[0], m2[1]); got != want {
		panic(got)
	}
}

// Nonliteral keys in composite literal.
func init() {
	const zero int = 1
	var v = []int{1 + zero: 42}
	if x := fmt.Sprint(v); x != "[0 0 42]" {
		panic(x)
	}
}

// Test for in-place initialization.
func init() {
	// struct
	type S struct {
		a, b int
	}
	s := S{1, 2}
	s = S{b: 3}
	if s.a != 0 {
		panic("s.a != 0")
	}
	if s.b != 3 {
		panic("s.b != 3")
	}
	s = S{}
	if s.a != 0 {
		panic("s.a != 0")
	}
	if s.b != 0 {
		panic("s.b != 0")
	}

	// array
	type A [4]int
	a := A{2, 4, 6, 8}
	a = A{1: 6, 2: 4}
	if a[0] != 0 {
		panic("a[0] != 0")
	}
	if a[1] != 6 {
		panic("a[1] != 6")
	}
	if a[2] != 4 {
		panic("a[2] != 4")
	}
	if a[3] != 0 {
		panic("a[3] != 0")
	}
	a = A{}
	if a[0] != 0 {
		panic("a[0] != 0")
	}
	if a[1] != 0 {
		panic("a[1] != 0")
	}
	if a[2] != 0 {
		panic("a[2] != 0")
	}
	if a[3] != 0 {
		panic("a[3] != 0")
	}
}

// Regression test for https://golang.org/issue/10127:
// composite literal clobbers destination before reading from it.
func init() {
	// map
	{
		type M map[string]int
		m := M{"x": 1, "y": 2}
		m = M{"x": m["y"], "y": m["x"]}
		if m["x"] != 2 || m["y"] != 1 {
			panic(fmt.Sprint(m))
		}

		n := M{"x": 3}
		m, n = M{"x": n["x"]}, M{"x": m["x"]} // parallel assignment
		if got := fmt.Sprint(m["x"], n["x"]); got != "3 2" {
			panic(got)
		}
	}

	// struct
	{
		type T struct{ x, y, z int }
		t := T{x: 1, y: 2, z: 3}

		t = T{x: t.y, y: t.z, z: t.x} // all fields
		if got := fmt.Sprint(t); got != "{2 3 1}" {
			panic(got)
		}

		t = T{x: t.y, y: t.z + 3} // not all fields
		if got := fmt.Sprint(t); got != "{3 4 0}" {
			panic(got)
		}

		u := T{x: 5, y: 6, z: 7}
		t, u = T{x: u.x}, T{x: t.x} // parallel assignment
		if got := fmt.Sprint(t, u); got != "{5 0 0} {3 0 0}" {
			panic(got)
		}
	}

	// array
	{
		a := [3]int{0: 1, 1: 2, 2: 3}

		a = [3]int{0: a[1], 1: a[2], 2: a[0]} //  all elements
		if got := fmt.Sprint(a); got != "[2 3 1]" {
			panic(got)
		}

		a = [3]int{0: a[1], 1: a[2] + 3} //  not all elements
		if got := fmt.Sprint(a); got != "[3 4 0]" {
			panic(got)
		}

		b := [3]int{0: 5, 1: 6, 2: 7}
		a, b = [3]int{0: b[0]}, [3]int{0: a[0]} // parallel assignment
		if got := fmt.Sprint(a, b); got != "[5 0 0] [3 0 0]" {
			panic(got)
		}
	}

	// slice
	{
		s := []int{0: 1, 1: 2, 2: 3}

		s = []int{0: s[1], 1: s[2], 2: s[0]} //  all elements
		if got := fmt.Sprint(s); got != "[2 3 1]" {
			panic(got)
		}

		s = []int{0: s[1], 1: s[2] + 3} //  not all elements
		if got := fmt.Sprint(s); got != "[3 4]" {
			panic(got)
		}

		t := []int{0: 5, 1: 6, 2: 7}
		s, t = []int{0: t[0]}, []int{0: s[0]} // parallel assignment
		if got := fmt.Sprint(s, t); got != "[5] [3]" {
			panic(got)
		}
	}
}

// Regression test for https://golang.org/issue/13341:
// within a map literal, if a key expression is a composite literal,
// Go 1.5 allows its type to be omitted.  An & operation may be implied.
func init() {
	type S struct{ x int }
	// same as map[*S]bool{&S{x: 1}: true}
	m := map[*S]bool{{x: 1}: true}
	for s := range m {
		if s.x != 1 {
			panic(s) // wrong key
		}
		return
	}
	panic("map is empty")
}

func main() {
}


================================================
FILE: go/ssa/interp/testdata/convert.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test conversion operations.

package main

func left(x int)  { _ = 1 << x }
func right(x int) { _ = 1 >> x }

func main() {
	wantPanic(
		func() {
			left(-1)
		},
		"runtime error: negative shift amount",
	)
	wantPanic(
		func() {
			right(-1)
		},
		"runtime error: negative shift amount",
	)
	wantPanic(
		func() {
			const maxInt32 = 1<<31 - 1
			var idx int64 = maxInt32*2 + 8
			x := make([]int, 16)
			_ = x[idx]
		},
		"runtime error: runtime error: index out of range [4294967302] with length 16",
	)
}

func wantPanic(fn func(), s string) {
	defer func() {
		err := recover()
		if err == nil {
			panic("expected panic")
		}
		if got := err.(error).Error(); got != s {
			panic("expected panic " + s + " got " + got)
		}
	}()
	fn()
}


================================================
FILE: go/ssa/interp/testdata/coverage.go
================================================
// This interpreter test is designed to run very quickly yet provide
// some coverage of a broad selection of constructs.
//
// Validate this file with 'go run' after editing.
// TODO(adonovan): break this into small files organized by theme.

package main

import (
	"fmt"
	"reflect"
	"strings"
)

func init() {
	// Call of variadic function with (implicit) empty slice.
	if x := fmt.Sprint(); x != "" {
		panic(x)
	}
}

type empty interface{}

type I interface {
	f() int
}

type T struct{ z int }

func (t T) f() int { return t.z }

func use(interface{}) {}

var counter = 2

// Test initialization, including init blocks containing 'return'.
// Assertion is in main.
func init() {
	counter *= 3
	return
	counter *= 3
}

func init() {
	counter *= 5
	return
	counter *= 5
}

// Recursion.
func fib(x int) int {
	if x < 2 {
		return x
	}
	return fib(x-1) + fib(x-2)
}

func fibgen(ch chan int) {
	for x := 0; x < 10; x++ {
		ch <- fib(x)
	}
	close(ch)
}

// Goroutines and channels.
func init() {
	ch := make(chan int)
	go fibgen(ch)
	var fibs []int
	for v := range ch {
		fibs = append(fibs, v)
		if len(fibs) == 10 {
			break
		}
	}
	if x := fmt.Sprint(fibs); x != "[0 1 1 2 3 5 8 13 21 34]" {
		panic(x)
	}
}

// Test of aliasing.
func init() {
	type S struct {
		a, b string
	}

	s1 := []string{"foo", "bar"}
	s2 := s1 // creates an alias
	s2[0] = "wiz"
	if x := fmt.Sprint(s1, s2); x != "[wiz bar] [wiz bar]" {
		panic(x)
	}

	pa1 := &[2]string{"foo", "bar"}
	pa2 := pa1 // creates an alias
	pa2[0] = "wiz"
	if x := fmt.Sprint(*pa1, *pa2); x != "[wiz bar] [wiz bar]" {
		panic(x)
	}

	a1 := [2]string{"foo", "bar"}
	a2 := a1 // creates a copy
	a2[0] = "wiz"
	if x := fmt.Sprint(a1, a2); x != "[foo bar] [wiz bar]" {
		panic(x)
	}

	t1 := S{"foo", "bar"}
	t2 := t1 // copy
	t2.a = "wiz"
	if x := fmt.Sprint(t1, t2); x != "{foo bar} {wiz bar}" {
		panic(x)
	}
}

func main() {
	print() // legal

	if counter != 2*3*5 {
		panic(counter)
	}

	// Test builtins (e.g. complex) preserve named argument types.
	type N complex128
	var n N
	n = complex(1.0, 2.0)
	if n != complex(1.0, 2.0) {
		panic(n)
	}
	if x := reflect.TypeOf(n).String(); x != "main.N" {
		panic(x)
	}
	if real(n) != 1.0 || imag(n) != 2.0 {
		panic(n)
	}

	// Channel + select.
	ch := make(chan int, 1)
	select {
	case ch <- 1:
		// ok
	default:
		panic("couldn't send")
	}
	if <-ch != 1 {
		panic("couldn't receive")
	}
	// A "receive" select-case that doesn't declare its vars.  (regression test)
	anint := 0
	ok := false
	select {
	case anint, ok = <-ch:
	case anint = <-ch:
	default:
	}
	_ = anint
	_ = ok

	// Anon structs with methods.
	anon := struct{ T }{T: T{z: 1}}
	if x := anon.f(); x != 1 {
		panic(x)
	}
	var i I = anon
	if x := i.f(); x != 1 {
		panic(x)
	}
	// NB. precise output of reflect.Type.String is undefined.
	if x := reflect.TypeOf(i).String(); x != "struct { main.T }" && x != "struct{main.T}" {
		panic(x)
	}

	// fmt.
	const message = "Hello, World!"
	if fmt.Sprint("Hello", ", ", "World", "!") != message {
		panic("oops")
	}

	// Type assertion.
	type S struct {
		f int
	}
	var e empty = S{f: 42}
	switch v := e.(type) {
	case S:
		if v.f != 42 {
			panic(v.f)
		}
	default:
		panic(reflect.TypeOf(v))
	}
	if i, ok := e.(I); ok {
		panic(i)
	}

	// Switch.
	var x int
	switch x {
	case 1:
		panic(x)
		fallthrough
	case 2, 3:
		panic(x)
	default:
		// ok
	}
	// empty switch
	switch {
	}
	// empty switch
	switch {
	default:
	}
	// empty switch
	switch {
	default:
		fallthrough
	case false:
	}

	// string -> []rune conversion.
	use([]rune("foo"))

	// Calls of form x.f().
	type S2 struct {
		f func() int
	}
	S2{f: func() int { return 1 }}.f() // field is a func value
	T{}.f()                            // method call
	i.f()                              // interface method invocation
	(interface {
		f() int
	}(T{})).f() // anon interface method invocation

	// Map lookup.
	if v, ok := map[string]string{}["foo5"]; v != "" || ok {
		panic("oops")
	}

	// Regression test: implicit address-taken struct literal
	// inside literal map element.
	_ = map[int]*struct{}{0: {}}
}

type mybool bool

func (mybool) f() {}

func init() {
	type mybool bool
	var b mybool
	var i interface{} = b || b // result preserves types of operands
	_ = i.(mybool)

	i = false && b // result preserves type of "typed" operand
	_ = i.(mybool)

	i = b || true // result preserves type of "typed" operand
	_ = i.(mybool)
}

func init() {
	var x, y int
	var b mybool = x == y // x==y is an untyped bool
	b.f()
}

// Simple closures.
func init() {
	b := 3
	f := func(a int) int {
		return a + b
	}
	b++
	if x := f(1); x != 5 { // 1+4 == 5
		panic(x)
	}
	b++
	if x := f(2); x != 7 { // 2+5 == 7
		panic(x)
	}
	if b := f(1) < 16 || f(2) < 17; !b {
		panic("oops")
	}
}

// Shifts.
func init() {
	var i int64 = 1
	var u uint64 = 1 << 32
	if x := i << uint32(u); x != 1 {
		panic(x)
	}
	if x := i << uint64(u); x != 0 {
		panic(x)
	}
}

// Implicit conversion of delete() key operand.
func init() {
	type I interface{}
	m := make(map[I]bool)
	m[1] = true
	m[I(2)] = true
	if len(m) != 2 {
		panic(m)
	}
	delete(m, I(1))
	delete(m, 2)
	if len(m) != 0 {
		panic(m)
	}
}

// An I->I conversion always succeeds.
func init() {
	var x I
	if I(x) != I(nil) {
		panic("I->I conversion failed")
	}
}

// An I->I type-assert fails iff the value is nil.
func init() {
	defer func() {
		r := fmt.Sprint(recover())
		// Exact error varies by toolchain.
		if r != "runtime error: interface conversion: interface is nil, not main.I" &&
			r != "interface conversion: interface is nil, not main.I" {
			panic("I->I type assertion succeeded for nil value")
		}
	}()
	var x I
	_ = x.(I)
}

//////////////////////////////////////////////////////////////////////
// Variadic bridge methods and interface thunks.

type VT int

var vcount = 0

func (VT) f(x int, y ...string) {
	vcount++
	if x != 1 {
		panic(x)
	}
	if len(y) != 2 || y[0] != "foo" || y[1] != "bar" {
		panic(y)
	}
}

type VS struct {
	VT
}

type VI interface {
	f(x int, y ...string)
}

func init() {
	foobar := []string{"foo", "bar"}
	var s VS
	s.f(1, "foo", "bar")
	s.f(1, foobar...)
	if vcount != 2 {
		panic("s.f not called twice")
	}

	fn := VI.f
	fn(s, 1, "foo", "bar")
	fn(s, 1, foobar...)
	if vcount != 4 {
		panic("I.f not called twice")
	}
}

// Multiple labels on same statement.
func multipleLabels() {
	var trace []int
	i := 0
one:
two:
	for ; i < 3; i++ {
		trace = append(trace, i)
		switch i {
		case 0:
			continue two
		case 1:
			i++
			goto one
		case 2:
			break two
		}
	}
	if x := fmt.Sprint(trace); x != "[0 1 2]" {
		panic(x)
	}
}

func init() {
	multipleLabels()
}

func init() {
	// Struct equivalence ignores blank fields.
	type s struct{ x, _, z int }
	s1 := s{x: 1, z: 3}
	s2 := s{x: 1, z: 3}
	if s1 != s2 {
		panic("not equal")
	}
}

func init() {
	// A slice var can be compared to const []T nil.
	var i interface{} = []string{"foo"}
	var j interface{} = []string(nil)
	if i.([]string) == nil {
		panic("expected i non-nil")
	}
	if j.([]string) != nil {
		panic("expected j nil")
	}
	// But two slices cannot be compared, even if one is nil.
	defer func() {
		r := fmt.Sprint(recover())
		if !(strings.Contains(r, "compar") && strings.Contains(r, "[]string")) {
			panic("want panic from slice comparison, got " + r)
		}
	}()
	_ = i == j // interface comparison recurses on types
}

func init() {
	// Regression test for SSA renaming bug.
	var ints []int
	for range "foo" {
		var x int
		x++
		ints = append(ints, x)
	}
	if fmt.Sprint(ints) != "[1 1 1]" {
		panic(ints)
	}
}

// Regression test for issue 6949:
// []byte("foo") is not a constant since it allocates memory.
func init() {
	var r string
	for i, b := range "ABC" {
		x := []byte("abc")
		x[i] = byte(b)
		r += string(x)
	}
	if r != "AbcaBcabC" {
		panic(r)
	}
}

// Test of 3-operand x[lo:hi:max] slice.
func init() {
	s := []int{0, 1, 2, 3}
	lenCapLoHi := func(x []int) [4]int { return [4]int{len(x), cap(x), x[0], x[len(x)-1]} }
	if got := lenCapLoHi(s[1:3]); got != [4]int{2, 3, 1, 2} {
		panic(got)
	}
	if got := lenCapLoHi(s[1:3:3]); got != [4]int{2, 2, 1, 2} {
		panic(got)
	}
	max := 3
	if "a"[0] == 'a' {
		max = 2 // max is non-constant, even in SSA form
	}
	if got := lenCapLoHi(s[1:2:max]); got != [4]int{1, 1, 1, 1} {
		panic(got)
	}
}

var one = 1 // not a constant

// Test makeslice.
func init() {
	check := func(s []string, wantLen, wantCap int) {
		if len(s) != wantLen {
			panic(len(s))
		}
		if cap(s) != wantCap {
			panic(cap(s))
		}
	}
	//                                       SSA form:
	check(make([]string, 10), 10, 10)     // new([10]string)[:10]
	check(make([]string, one), 1, 1)      // make([]string, one, one)
	check(make([]string, 0, 10), 0, 10)   // new([10]string)[:0]
	check(make([]string, 0, one), 0, 1)   // make([]string, 0, one)
	check(make([]string, one, 10), 1, 10) // new([10]string)[:one]
	check(make([]string, one, one), 1, 1) // make([]string, one, one)
}

// Test that a nice error is issued by indirection wrappers.
func init() {
	var ptr *T
	var i I = ptr

	defer func() {
		r := fmt.Sprint(recover())
		// Exact error varies by toolchain:
		if r != "runtime error: value method (main.T).f called using nil *main.T pointer" &&
			r != "value method (main.T).f called using nil *main.T pointer" {
			panic("want panic from call with nil receiver, got " + r)
		}
	}()
	i.f()
	panic("unreachable")
}

// Regression test for a subtle bug in which copying values would causes
// subcomponents of aggregate variables to change address, breaking
// aliases.
func init() {
	type T struct{ f int }
	var x T
	p := &x.f
	x = T{}
	*p = 1
	if x.f != 1 {
		panic("lost store")
	}
	if p != &x.f {
		panic("unstable address")
	}
}


================================================
FILE: go/ssa/interp/testdata/deepequal.go
================================================
// This interpreter test is designed to test the test copy of DeepEqual.
//
// Validate this file with 'go run' after editing.

package main

import "reflect"

func assert(cond bool) {
	if !cond {
		panic("failed")
	}
}

type X int
type Y struct {
	y *Y
	z [3]int
}

var (
	a = []int{0, 1, 2, 3}
	b = []X{0, 1, 2, 3}
	c = map[int]string{0: "zero", 1: "one"}
	d = map[X]string{0: "zero", 1: "one"}
	e = &Y{}
	f = (*Y)(nil)
	g = &Y{y: e}
	h *Y
)

func init() {
	h = &Y{} // h->h
	h.y = h
}

func main() {
	assert(reflect.DeepEqual(nil, nil))
	assert(reflect.DeepEqual((*int)(nil), (*int)(nil)))
	assert(!reflect.DeepEqual(nil, (*int)(nil)))

	assert(reflect.DeepEqual(0, 0))
	assert(!reflect.DeepEqual(0, int64(0)))

	assert(!reflect.DeepEqual("", 0))

	assert(reflect.DeepEqual(a, []int{0, 1, 2, 3}))
	assert(!reflect.DeepEqual(a, []int{0, 1, 2}))
	assert(!reflect.DeepEqual(a, []int{0, 1, 0, 3}))

	assert(reflect.DeepEqual(b, []X{0, 1, 2, 3}))
	assert(!reflect.DeepEqual(b, []X{0, 1, 0, 3}))

	assert(reflect.DeepEqual(c, map[int]string{0: "zero", 1: "one"}))
	assert(!reflect.DeepEqual(c, map[int]string{0: "zero", 1: "one", 2: "two"}))
	assert(!reflect.DeepEqual(c, map[int]string{1: "one", 2: "two"}))
	assert(!reflect.DeepEqual(c, map[int]string{1: "one"}))

	assert(reflect.DeepEqual(d, map[X]string{0: "zero", 1: "one"}))
	assert(!reflect.DeepEqual(d, map[int]string{0: "zero", 1: "one"}))

	assert(reflect.DeepEqual(e, &Y{}))
	assert(reflect.DeepEqual(e, &Y{z: [3]int{0, 0, 0}}))
	assert(!reflect.DeepEqual(e, &Y{z: [3]int{0, 1, 0}}))

	assert(reflect.DeepEqual(f, (*Y)(nil)))
	assert(!reflect.DeepEqual(f, nil))

	// eq_h -> eq_h. Pointer structure and elements are equal so DeepEqual.
	eq_h := &Y{}
	eq_h.y = eq_h
	assert(reflect.DeepEqual(h, eq_h))

	// deepeq_h->h->h. Pointed to elem of (deepeq_h, h) are (h,h). (h,h) are deep equal so h and deepeq_h are DeepEqual.
	deepeq_h := &Y{}
	deepeq_h.y = h
	assert(reflect.DeepEqual(h, deepeq_h))

	distinct := []interface{}{a, b, c, d, e, f, g, h}
	for x := range distinct {
		for y := range distinct {
			assert((x == y) == reflect.DeepEqual(distinct[x], distinct[y]))
		}
	}

	// anonymous struct types.
	assert(reflect.DeepEqual(struct{}{}, struct{}{}))
	assert(reflect.DeepEqual(struct{ x int }{1}, struct{ x int }{1}))
	assert(!reflect.DeepEqual(struct{ x int }{}, struct{ x int }{5}))
	assert(!reflect.DeepEqual(struct{ x, y int }{0, 1}, struct{ x int }{0}))
	assert(reflect.DeepEqual(struct{ x, y int }{2, 3}, struct{ x, y int }{2, 3}))
	assert(!reflect.DeepEqual(struct{ x, y int }{4, 5}, struct{ x, y int }{4, 6}))
}


================================================
FILE: go/ssa/interp/testdata/defer.go
================================================
package main

// Tests of defer.  (Deferred recover() belongs is recover.go.)

import "fmt"

func deferMutatesResults(noArgReturn bool) (a, b int) {
	defer func() {
		if a != 1 || b != 2 {
			panic(fmt.Sprint(a, b))
		}
		a, b = 3, 4
	}()
	if noArgReturn {
		a, b = 1, 2
		return
	}
	return 1, 2
}

func init() {
	a, b := deferMutatesResults(true)
	if a != 3 || b != 4 {
		panic(fmt.Sprint(a, b))
	}
	a, b = deferMutatesResults(false)
	if a != 3 || b != 4 {
		panic(fmt.Sprint(a, b))
	}
}

// We concatenate init blocks to make a single function, but we must
// run defers at the end of each block, not the combined function.
var deferCount = 0

func init() {
	deferCount = 1
	defer func() {
		deferCount++
	}()
	// defer runs HERE
}

func init() {
	// Strictly speaking the spec says deferCount may be 0 or 2
	// since the relative order of init blocks is unspecified.
	if deferCount != 2 {
		panic(deferCount) // defer call has not run!
	}
}

func main() {
}


================================================
FILE: go/ssa/interp/testdata/fieldprom.go
================================================
package main

// Tests of field promotion logic.

type A struct {
	x int
	y *int
}

type B struct {
	p int
	q *int
}

type C struct {
	A
	*B
}

type D struct {
	a int
	C
}

func assert(cond bool) {
	if !cond {
		panic("failed")
	}
}

func f1(c C) {
	assert(c.x == c.A.x)
	assert(c.y == c.A.y)
	assert(&c.x == &c.A.x)
	assert(&c.y == &c.A.y)

	assert(c.p == c.B.p)
	assert(c.q == c.B.q)
	assert(&c.p == &c.B.p)
	assert(&c.q == &c.B.q)

	c.x = 1
	*c.y = 1
	c.p = 1
	*c.q = 1
}

func f2(c *C) {
	assert(c.x == c.A.x)
	assert(c.y == c.A.y)
	assert(&c.x == &c.A.x)
	assert(&c.y == &c.A.y)

	assert(c.p == c.B.p)
	assert(c.q == c.B.q)
	assert(&c.p == &c.B.p)
	assert(&c.q == &c.B.q)

	c.x = 1
	*c.y = 1
	c.p = 1
	*c.q = 1
}

func f3(d D) {
	assert(d.x == d.C.A.x)
	assert(d.y == d.C.A.y)
	assert(&d.x == &d.C.A.x)
	assert(&d.y == &d.C.A.y)

	assert(d.p == d.C.B.p)
	assert(d.q == d.C.B.q)
	assert(&d.p == &d.C.B.p)
	assert(&d.q == &d.C.B.q)

	d.x = 1
	*d.y = 1
	d.p = 1
	*d.q = 1
}

func f4(d *D) {
	assert(d.x == d.C.A.x)
	assert(d.y == d.C.A.y)
	assert(&d.x == &d.C.A.x)
	assert(&d.y == &d.C.A.y)

	assert(d.p == d.C.B.p)
	assert(d.q == d.C.B.q)
	assert(&d.p == &d.C.B.p)
	assert(&d.q == &d.C.B.q)

	d.x = 1
	*d.y = 1
	d.p = 1
	*d.q = 1
}

func main() {
	y := 123
	c := C{
		A{x: 42, y: &y},
		&B{p: 42, q: &y},
	}

	assert(&c.x == &c.A.x)

	f1(c)
	f2(&c)

	d := D{C: c}
	f3(d)
	f4(&d)
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue52342.go
================================================
package main

func main() {
	var d byte

	d = 1
	d <<= 256
	if d != 0 {
		panic(d)
	}

	d = 1
	d >>= 256
	if d != 0 {
		panic(d)
	}
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue52835.go
================================================
package main

var called bool

type I interface {
	Foo()
}

type A struct{}

func (a A) Foo() {
	called = true
}

func lambda[X I]() func() func() {
	return func() func() {
		var x X
		return x.Foo
	}
}

func main() {
	lambda[A]()()()
	if !called {
		panic(called)
	}
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue55086.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

func a() (r string) {
	s := "initial"
	var p *struct{ i int }
	defer func() {
		recover()
		r = s
	}()

	s, p.i = "set", 2 // s must be set before p.i panics
	return "unreachable"
}

func b() (r string) {
	s := "initial"
	fn := func() []int { panic("") }
	defer func() {
		recover()
		r = s
	}()

	s, fn()[0] = "set", 2 // fn() panics before any assignment occurs
	return "unreachable"
}

func c() (r string) {
	s := "initial"
	var p map[int]int
	defer func() {
		recover()
		r = s
	}()

	s, p[0] = "set", 2 //s must be set before p[0] index panics"
	return "unreachable"
}

func d() (r string) {
	s := "initial"
	var p map[int]int
	defer func() {
		recover()
		r = s
	}()
	fn := func() int { panic("") }

	s, p[0] = "set", fn() // fn() panics before s is set
	return "unreachable"
}

func e() (r string) {
	s := "initial"
	p := map[int]int{}
	defer func() {
		recover()
		r = s
	}()
	fn := func() int { panic("") }

	s, p[fn()] = "set", 0 // fn() panics before any assignment occurs
	return "unreachable"
}

func f() (r string) {
	s := "initial"
	p := []int{}
	defer func() {
		recover()
		r = s
	}()

	s, p[1] = "set", 0 // p[1] panics after s is set
	return "unreachable"
}

func g() (r string) {
	s := "initial"
	p := map[any]any{}
	defer func() {
		recover()
		r = s
	}()
	var i any = func() {}
	s, p[i] = "set", 0 // p[i] panics after s is set
	return "unreachable"
}

func h() (r string) {
	fail := false
	defer func() {
		recover()
		if fail {
			r = "fail"
		} else {
			r = "success"
		}
	}()

	type T struct{ f int }
	var p *struct{ *T }

	// The implicit "p.T" operand should be evaluated in phase 1 (and panic),
	// before the "fail = true" assignment in phase 2.
	fail, p.f = true, 0
	return "unreachable"
}

func main() {
	for _, test := range []struct {
		fn   func() string
		want string
		desc string
	}{
		{a, "set", "s must be set before p.i panics"},
		{b, "initial", "p() panics before s is set"},
		{c, "set", "s must be set before p[0] index panics"},
		{d, "initial", "fn() panics before s is set"},
		{e, "initial", "fn() panics before s is set"},
		{f, "set", "p[1] panics after s is set"},
		{g, "set", "p[i] panics after s is set"},
		{h, "success", "p.T panics before fail is set"},
	} {
		if test.fn() != test.want {
			panic(test.desc)
		}
	}
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue55115.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import "reflect"

func main() {
	type MyByte byte
	type MyRune rune
	type MyString string

	a := []MyByte{'a', 'b', 'c'}
	if s := string(a); s != "abc" {
		panic(s)
	}

	b := []MyRune{'五', '五'}
	if s := string(b); s != "五五" {
		panic(s)
	}

	c := []MyByte{'l', 'o', 'r', 'e', 'm'}
	if s := MyString(c); s != MyString("lorem") {
		panic(s)
	}

	d := "lorem"
	if a := []MyByte(d); !reflect.DeepEqual(a, []MyByte{'l', 'o', 'r', 'e', 'm'}) {
		panic(a)
	}

	e := 42
	if s := MyString(e); s != "*" {
		panic(s)
	}
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue66783.go
================================================
package main

import "fmt"

func Fn[N any]() (any, any, any) {
	// Very recursive type to exercise substitution.
	type t[x any, ignored *N] struct {
		f  x
		g  N
		nx *t[x, *N]
		nn *t[N, *N]
	}
	n := t[N, *N]{}
	s := t[string, *N]{}
	i := t[int, *N]{}
	return n, s, i
}

func main() {

	sn, ss, si := Fn[string]()
	in, is, ii := Fn[int]()

	for i, t := range []struct {
		x, y any
		want bool
	}{
		{sn, ss, true},  // main.t[string;string,*string] == main.t[string;string,*string]
		{sn, si, false}, // main.t[string;string,*string] != main.t[string;int,*string]
		{sn, in, false}, // main.t[string;string,*string] != main.t[int;int,*int]
		{sn, is, false}, // main.t[string;string,*string] != main.t[int;string,*int]
		{sn, ii, false}, // main.t[string;string,*string] != main.t[int;int,*int]

		{ss, si, false}, // main.t[string;string,*string] != main.t[string;int,*string]
		{ss, in, false}, // main.t[string;string,*string] != main.t[int;int,*int]
		{ss, is, false}, // main.t[string;string,*string] != main.t[int;string,*int]
		{ss, ii, false}, // main.t[string;string,*string] != main.t[int;int,*int]

		{si, in, false}, // main.t[string;int,*string] != main.t[int;int,*int]
		{si, is, false}, // main.t[string;int,*string] != main.t[int;string,*int]
		{si, ii, false}, // main.t[string;int,*string] != main.t[int;int,*int]

		{in, is, false}, // main.t[int;int,*int] != main.t[int;string,*int]
		{in, ii, true},  // main.t[int;int,*int] == main.t[int;int,*int]

		{is, ii, false}, // main.t[int;string,*int] != main.t[int;int,*int]
	} {
		x, y, want := t.x, t.y, t.want
		if got := x == y; got != want {
			msg := fmt.Sprintf("(case %d) %T == %T. got %v. wanted %v", i, x, y, got, want)
			panic(msg)
		}
	}
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue69298.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
)

type Seq[V any] func(yield func(V) bool)

func AppendSeq[Slice ~[]E, E any](s Slice, seq Seq[E]) Slice {
	for v := range seq {
		s = append(s, v)
	}
	return s
}

func main() {
	seq := func(yield func(int) bool) {
		for i := 0; i < 10; i += 2 {
			if !yield(i) {
				return
			}
		}
	}

	s := AppendSeq([]int{1, 2}, seq)
	fmt.Println(s)
}


================================================
FILE: go/ssa/interp/testdata/fixedbugs/issue69929.go
================================================
package main

// This is a regression test for a bug (#69929) in
// the SSA interpreter in which it would not execute phis in parallel.
//
// The insert function below has interdependent phi nodes:
//
//	  entry:
//		t0 = *root       // t0 is x or y before loop
//		jump test
//	  body:
//		print(t5)      // t5 is x at loop entry
//		t3 = t5.Child    // t3 is x after loop
//		jump test
//	  test:
//		t5 = phi(t0, t3) // t5 is x at loop entry
//		t6 = phi(t0, t5) // t6 is y at loop entry
//		if t5 != nil goto body else done
//	  done:
//		print(t6)
//		return
//
// The two phis:
//
//	t5 = phi(t0, t3)
//	t6 = phi(t0, t5)
//
// must be executed in parallel as if they were written in Go
// as:
//
//	t5, t6 = phi(t0, t3), phi(t0, t5)
//
// with the second phi node observing the original, not
// updated, value of t5. (In more complex examples, the phi
// nodes may be mutually recursive, breaking partial solutions
// based on simple reordering of the phi instructions. See the
// Briggs paper for detail.)
//
// The correct behavior is print(1, root); print(2, root); print(3, root).
// The previous incorrect behavior had print(2, nil).

func main() {
	insert()
	print(3, root)
}

var root = new(node)

type node struct{ child *node }

func insert() {
	x := root
	y := x
	for x != nil {
		y = x
		print(1, y)
		x = x.child
	}
	print(2, y)
}

func print(order int, ptr *node) {
	println(order, ptr)
	if ptr != root {
		panic(ptr)
	}
}


================================================
FILE: go/ssa/interp/testdata/forvarlifetime_go122.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"reflect"
)

func main() {
	test_init()
	bound()
	manyvars()
	nocond()
	nopost()
	address_sequences()
	post_escapes()

	// Clones from cmd/compile/internal/loopvar/testdata .
	for_complicated_esc_address()
	for_esc_address()
	for_esc_closure()
	for_esc_method()
}

// After go1.22, each i will have a distinct address and value.
var distinct = func(m, n int) []*int {
	var r []*int
	for i := m; i <= n; i++ {
		r = append(r, &i)
	}
	return r
}(3, 5)

func test_init() {
	if len(distinct) != 3 {
		panic(distinct)
	}
	for i, v := range []int{3, 4, 5} {
		if v != *(distinct[i]) {
			panic(distinct)
		}
	}
}

func bound() {
	b := func(k int) func() int {
		var f func() int
		for i := 0; i < k; i++ {
			f = func() int { return i } // address before post updates i. So last value in the body.
		}
		return f
	}

	if got := b(0); got != nil {
		panic(got)
	}
	if got := b(5); got() != 4 {
		panic(got())
	}
}

func manyvars() {
	// Tests declaring many variables and having one in the middle escape.
	var f func() int
	for i, j, k, l, m, n, o, p := 7, 6, 5, 4, 3, 2, 1, 0; p < 6; l, p = l+1, p+1 {
		_, _, _, _, _, _, _, _ = i, j, k, l, m, n, o, p
		f = func() int { return l } // address *before* post updates l
	}
	if f() != 9 { // l == p+4
		panic(f())
	}
}

func nocond() {
	var c, b, e *int
	for p := 0; ; p++ {
		if p%7 == 0 {
			c = &p
			continue
		} else if p == 20 {
			b = &p
			break
		}
		e = &p
	}

	if *c != 14 {
		panic(c)
	}
	if *b != 20 {
		panic(b)
	}
	if *e != 19 {
		panic(e)
	}
}

func nopost() {
	var first, last *int
	for p := 0; p < 20; {
		if first == nil {
			first = &p
		}
		last = &p

		p++
	}

	if *first != 1 {
		panic(first)
	}
	if *last != 20 {
		panic(last)
	}
}

func address_sequences() {
	var c, b, p []*int

	cond := func(x *int) bool {
		c = append(c, x)
		return *x < 5
	}
	body := func(x *int) {
		b = append(b, x)
	}
	post := func(x *int) {
		p = append(p, x)
		(*x)++
	}
	for i := 0; cond(&i); post(&i) {
		body(&i)
	}

	if c[0] == c[1] {
		panic(c)
	}

	if !reflect.DeepEqual(c[:5], b) {
		panic(c)
	}

	if !reflect.DeepEqual(c[1:], p) {
		panic(c)
	}

	if !reflect.DeepEqual(b[1:], p[:4]) {
		panic(b)
	}
}

func post_escapes() {
	var p []*int
	post := func(x *int) {
		p = append(p, x)
		(*x)++
	}

	for i := 0; i < 5; post(&i) {
	}

	var got []int
	for _, x := range p {
		got = append(got, *x)
	}
	if want := []int{1, 2, 3, 4, 5}; !reflect.DeepEqual(got, want) {
		panic(got)
	}
}

func for_complicated_esc_address() {
	// Clone of for_complicated_esc_adress.go
	ss, sa := shared(23)
	ps, pa := private(23)
	es, ea := experiment(23)

	if ss != ps || ss != es || ea != pa || sa == pa {
		println("shared s, a", ss, sa, "; private, s, a", ps, pa, "; experiment s, a", es, ea)
		panic("for_complicated_esc_address")
	}
}

func experiment(x int) (int, int) {
	sum := 0
	var is []*int
	for i := x; i != 1; i = i / 2 {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}

	return sum, asum
}

func private(x int) (int, int) {
	sum := 0
	var is []*int
	I := x
	for ; I != 1; I = I / 2 {
		i := I
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				I = i
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
		I = i
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}

	return sum, asum
}

func shared(x int) (int, int) {
	sum := 0
	var is []*int
	i := x
	for ; i != 1; i = i / 2 {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}
	return sum, asum
}

func for_esc_address() {
	// Clone of for_esc_address.go
	sum := 0
	var is []*int
	for i := 0; i < 10; i++ {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, &i)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, pi := range is {
		sum += *pi
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected ", 20, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_address")
	}
}

func for_esc_closure() {
	var is []func() int

	// Clone of for_esc_closure.go
	sum := 0
	for i := 0; i < 10; i++ {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, func() int {
				if i%17 == 15 {
					i++
				}
				return i
			})
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected ", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, f := range is {
		sum += f()
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected ", 20, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_closure")
	}
}

type I int

func (x *I) method() int {
	return int(*x)
}

func for_esc_method() {
	// Clone of for_esc_method.go
	var is []func() int
	sum := 0
	for i := I(0); int(i) < 10; i++ {
		for j := 0; j < 10; j++ {
			if int(i) == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, i.method)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected ", 90, ", saw ", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, m := range is {
		sum += m()
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected ", 20, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_method")
	}
}


================================================
FILE: go/ssa/interp/testdata/forvarlifetime_old.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.21

// goversion can be pinned to anything strictly before 1.22.

package main

import (
	"reflect"
)

func main() {
	test_init()
	bound()
	manyvars()
	nocond()
	nopost()
	address_sequences()
	post_escapes()

	// Clones from cmd/compile/internal/loopvar/testdata .
	for_complicated_esc_address()
	for_esc_address()
	for_esc_closure()
	for_esc_method()
}

// pre-go1.22 all of i will have the same address and the value of 6.
var same = func(m, n int) []*int {
	var r []*int
	for i := m; i <= n; i++ {
		r = append(r, &i)
	}
	return r
}(3, 5)

func test_init() {
	if len(same) != 3 {
		panic(same)
	}
	for i := range same {
		for j := range same {
			if !(same[i] == same[j]) {
				panic(same)
			}
		}
	}
	for i := range same {
		if *(same[i]) != 6 {
			panic(same)
		}
	}
}

func bound() {
	b := func(k int) func() int {
		var f func() int
		for i := 0; i < k; i++ {
			f = func() int { return i } // shared address will equal k.
		}
		return f
	}

	if got := b(0); got != nil {
		panic(got)
	}
	if got := b(5); got() != 5 {
		panic(got())
	}
}

func manyvars() {
	// Tests declaring many variables and having one in the middle escape.
	var f func() int
	for i, j, k, l, m, n, o, p := 7, 6, 5, 4, 3, 2, 1, 0; p < 6; l, p = l+1, p+1 {
		_, _, _, _, _, _, _, _ = i, j, k, l, m, n, o, p
		f = func() int { return l } // address *after* post updates l
	}
	if f() != 10 { // l == p+4
		panic(f())
	}
}

func nocond() {
	var c, b, e *int
	for p := 0; ; p++ {
		if p%7 == 0 {
			c = &p
			continue
		} else if p == 20 {
			b = &p
			break
		}
		e = &p
	}

	if *c != 20 {
		panic(c)
	}
	if *b != 20 {
		panic(b)
	}
	if *e != 20 {
		panic(e)
	}
}

func nopost() {
	var first, last *int
	for p := 0; p < 20; {
		if first == nil {
			first = &p
		}
		last = &p

		p++
	}

	if *first != 20 {
		panic(first)
	}
	if *last != 20 {
		panic(last)
	}
}

func address_sequences() {
	var c, b, p []*int

	cond := func(x *int) bool {
		c = append(c, x)
		return *x < 5
	}
	body := func(x *int) {
		b = append(b, x)
	}
	post := func(x *int) {
		p = append(p, x)
		(*x)++
	}
	for i := 0; cond(&i); post(&i) {
		body(&i)
	}

	if c[0] != c[1] {
		panic(c)
	}

	if !reflect.DeepEqual(c[:5], b) {
		panic(c)
	}

	if !reflect.DeepEqual(c[1:], p) {
		panic(c)
	}

	if !reflect.DeepEqual(b[1:], p[:4]) {
		panic(b)
	}
}

func post_escapes() {
	var p []*int
	post := func(x *int) {
		p = append(p, x)
		(*x)++
	}

	for i := 0; i < 5; post(&i) {
	}

	var got []int
	for _, x := range p {
		got = append(got, *x)
	}
	if want := []int{5, 5, 5, 5, 5}; !reflect.DeepEqual(got, want) {
		panic(got)
	}
}

func for_complicated_esc_address() {
	// Clone of for_complicated_esc_adress.go
	ss, sa := shared(23)
	ps, pa := private(23)
	es, ea := experiment(23)

	if ss != ps || ss != es || sa != ea || pa != 188 {
		println("shared s, a", ss, sa, "; private, s, a", ps, pa, "; experiment s, a", es, ea)
		panic("for_complicated_esc_address")
	}
}

func experiment(x int) (int, int) {
	sum := 0
	var is []*int
	for i := x; i != 1; i = i / 2 {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}

	return sum, asum
}

func private(x int) (int, int) {
	sum := 0
	var is []*int
	I := x
	for ; I != 1; I = I / 2 {
		i := I
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				I = i
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
		I = i
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}

	return sum, asum
}

func shared(x int) (int, int) {
	sum := 0
	var is []*int
	i := x
	for ; i != 1; i = i / 2 {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		i = i*3 + 1
		if i&1 == 0 {
			is = append(is, &i)
			for i&2 == 0 {
				i = i >> 1
			}
		} else {
			i = i + i
		}
	}

	asum := 0
	for _, pi := range is {
		asum += *pi
	}
	return sum, asum
}

func for_esc_address() {
	// Clone of for_esc_address.go
	sum := 0
	var is []*int
	for i := 0; i < 10; i++ {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, &i)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, pi := range is {
		sum += *pi
	}
	if sum != 10+10+10+10+10 {
		println("wrong sum, expected ", 50, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_address")
	}
}

func for_esc_closure() {
	// Clone of for_esc_closure.go
	var is []func() int
	sum := 0
	for i := 0; i < 10; i++ {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, func() int {
				if i%17 == 15 {
					i++
				}
				return i
			})
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected ", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, f := range is {
		sum += f()
	}
	if sum != 10+10+10+10+10 {
		println("wrong sum, expected ", 50, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_closure")
	}
}

type I int

func (x *I) method() int {
	return int(*x)
}

func for_esc_method() {
	// Clone of for_esc_method.go
	sum := 0
	var is []func() int
	for i := I(0); int(i) < 10; i++ {
		for j := 0; j < 10; j++ {
			if int(i) == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, i.method)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected ", 90, ", saw ", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, m := range is {
		sum += m()
	}
	if sum != 10+10+10+10+10 {
		println("wrong sum, expected ", 50, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("for_esc_method")
	}
}


================================================
FILE: go/ssa/interp/testdata/ifaceconv.go
================================================
package main

// Tests of interface conversions and type assertions.

type I0 interface {
}
type I1 interface {
	f()
}
type I2 interface {
	f()
	g()
}

type C0 struct{}
type C1 struct{}

func (C1) f() {}

type C2 struct{}

func (C2) f() {}
func (C2) g() {}

func main() {
	var i0 I0
	var i1 I1
	var i2 I2

	// Nil always causes a type assertion to fail, even to the
	// same type.
	if _, ok := i0.(I0); ok {
		panic("nil i0.(I0) succeeded")
	}
	if _, ok := i1.(I1); ok {
		panic("nil i1.(I1) succeeded")
	}
	if _, ok := i2.(I2); ok {
		panic("nil i2.(I2) succeeded")
	}

	// Conversions can't fail, even with nil.
	_ = I0(i0)

	_ = I0(i1)
	_ = I1(i1)

	_ = I0(i2)
	_ = I1(i2)
	_ = I2(i2)

	// Non-nil type assertions pass or fail based on the concrete type.
	i1 = C1{}
	if _, ok := i1.(I0); !ok {
		panic("C1 i1.(I0) failed")
	}
	if _, ok := i1.(I1); !ok {
		panic("C1 i1.(I1) failed")
	}
	if _, ok := i1.(I2); ok {
		panic("C1 i1.(I2) succeeded")
	}

	i1 = C2{}
	if _, ok := i1.(I0); !ok {
		panic("C2 i1.(I0) failed")
	}
	if _, ok := i1.(I1); !ok {
		panic("C2 i1.(I1) failed")
	}
	if _, ok := i1.(I2); !ok {
		panic("C2 i1.(I2) failed")
	}

	// Conversions can't fail.
	i1 = C1{}
	if I0(i1) == nil {
		panic("C1 I0(i1) was nil")
	}
	if I1(i1) == nil {
		panic("C1 I1(i1) was nil")
	}
}


================================================
FILE: go/ssa/interp/testdata/ifaceprom.go
================================================
package main

// Test of promotion of methods of an interface embedded within a
// struct.  In particular, this test exercises that the correct
// method is called.

type I interface {
	one() int
	two() string
}

type S struct {
	I
}

type impl struct{}

func (impl) one() int {
	return 1
}

func (impl) two() string {
	return "two"
}

func main() {
	var s S
	s.I = impl{}
	if one := s.I.one(); one != 1 {
		panic(one)
	}
	if one := s.one(); one != 1 {
		panic(one)
	}
	closOne := s.I.one
	if one := closOne(); one != 1 {
		panic(one)
	}
	closOne = s.one
	if one := closOne(); one != 1 {
		panic(one)
	}

	if two := s.I.two(); two != "two" {
		panic(two)
	}
	if two := s.two(); two != "two" {
		panic(two)
	}
	closTwo := s.I.two
	if two := closTwo(); two != "two" {
		panic(two)
	}
	closTwo = s.two
	if two := closTwo(); two != "two" {
		panic(two)
	}
}


================================================
FILE: go/ssa/interp/testdata/initorder.go
================================================
package main

import "fmt"

// Test of initialization order of package-level vars.

var counter int

func next() int {
	c := counter
	counter++
	return c
}

func next2() (x int, y int) {
	x = next()
	y = next()
	return
}

func makeOrder() int {
	_, _, _, _ = f, b, d, e
	return 0
}

func main() {
	// Initialization constraints:
	// - {f,b,c/d,e} < order  (ref graph traversal)
	// - order < {a}          (lexical order)
	// - b < c/d < e < f      (lexical order)
	// Solution: a b c/d e f
	abcdef := [6]int{a, b, c, d, e, f}
	if abcdef != [6]int{0, 1, 2, 3, 4, 5} {
		panic(abcdef)
	}

	// Initializers of even blank globals are evaluated.
	if g != 1 {
		panic(g)
	}
}

var order = makeOrder()

var a, b = next(), next()
var c, d = next2()
var e, f = next(), next()

var (
	g int
	_ = func() int { g = 1; return 0 }()
)

// ------------------------------------------------------------------------

var order2 []string

func create(x int, name string) int {
	order2 = append(order2, name)
	return x
}

var C = create(B+1, "C")
var A, B = create(1, "A"), create(2, "B")

// Initialization order of package-level value specs.
func init() {
	x := fmt.Sprint(order2)
	// Result varies by toolchain.  This is a spec bug.
	if x != "[B C A]" && // gc
		x != "[A B C]" { // go/types
		panic(x)
	}
	if C != 3 {
		panic(c)
	}
}


================================================
FILE: go/ssa/interp/testdata/methprom.go
================================================
package main

// Tests of method promotion logic.

type A struct{ magic int }

func (a A) x() {
	if a.magic != 1 {
		panic(a.magic)
	}
}
func (a *A) y() *A {
	return a
}

type B struct{ magic int }

func (b B) p() {
	if b.magic != 2 {
		panic(b.magic)
	}
}
func (b *B) q() {
	if b != theC.B {
		panic("oops")
	}
}

type I interface {
	f()
}

type impl struct{ magic int }

func (i impl) f() {
	if i.magic != 3 {
		panic("oops")
	}
}

type C struct {
	A
	*B
	I
}

func assert(cond bool) {
	if !cond {
		panic("failed")
	}
}

var theC = C{
	A: A{1},
	B: &B{2},
	I: impl{3},
}

func addr() *C {
	return &theC
}

func value() C {
	return theC
}

func main() {
	// address
	addr().x()
	if addr().y() != &theC.A {
		panic("oops")
	}
	addr().p()
	addr().q()
	addr().f()

	// addressable value
	var c C = value()
	c.x()
	if c.y() != &c.A {
		panic("oops")
	}
	c.p()
	c.q()
	c.f()

	// non-addressable value
	value().x()
	// value().y() // not in method set
	value().p()
	value().q()
	value().f()
}


================================================
FILE: go/ssa/interp/testdata/minmax.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"math"
)

func main() {
	TestMinFloat()
	TestMaxFloat()
	TestMinMaxInt()
	TestMinMaxUint8()
	TestMinMaxString()
}

func errorf(format string, args ...any) { panic(fmt.Sprintf(format, args...)) }
func fatalf(format string, args ...any) { panic(fmt.Sprintf(format, args...)) }

// derived from $GOROOT/src/runtime/minmax_test.go

var (
	zero    = math.Copysign(0, +1)
	negZero = math.Copysign(0, -1)
	inf     = math.Inf(+1)
	negInf  = math.Inf(-1)
	nan     = math.NaN()
)

var tests = []struct{ min, max float64 }{
	{1, 2},
	{-2, 1},
	{negZero, zero},
	{zero, inf},
	{negInf, zero},
	{negInf, inf},
	{1, inf},
	{negInf, 1},
}

var all = []float64{1, 2, -1, -2, zero, negZero, inf, negInf, nan}

func eq(x, y float64) bool {
	return x == y && math.Signbit(x) == math.Signbit(y)
}

func TestMinFloat() {
	for _, tt := range tests {
		if z := min(tt.min, tt.max); !eq(z, tt.min) {
			errorf("min(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.min)
		}
		if z := min(tt.max, tt.min); !eq(z, tt.min) {
			errorf("min(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.min)
		}
	}
	for _, x := range all {
		if z := min(nan, x); !math.IsNaN(z) {
			errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
		}
		if z := min(x, nan); !math.IsNaN(z) {
			errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
		}
	}
}

func TestMaxFloat() {
	for _, tt := range tests {
		if z := max(tt.min, tt.max); !eq(z, tt.max) {
			errorf("max(%v, %v) = %v, want %v", tt.min, tt.max, z, tt.max)
		}
		if z := max(tt.max, tt.min); !eq(z, tt.max) {
			errorf("max(%v, %v) = %v, want %v", tt.max, tt.min, z, tt.max)
		}
	}
	for _, x := range all {
		if z := max(nan, x); !math.IsNaN(z) {
			errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
		}
		if z := max(x, nan); !math.IsNaN(z) {
			errorf("min(%v, %v) = %v, want %v", nan, x, z, nan)
		}
	}
}

// testMinMax tests that min/max behave correctly on every pair of
// values in vals.
//
// vals should be a sequence of values in strictly ascending order.
func testMinMax[T int | uint8 | string](vals ...T) {
	for i, x := range vals {
		for _, y := range vals[i+1:] {
			if !(x < y) {
				fatalf("values out of order: !(%v < %v)", x, y)
			}

			if z := min(x, y); z != x {
				errorf("min(%v, %v) = %v, want %v", x, y, z, x)
			}
			if z := min(y, x); z != x {
				errorf("min(%v, %v) = %v, want %v", y, x, z, x)
			}

			if z := max(x, y); z != y {
				errorf("max(%v, %v) = %v, want %v", x, y, z, y)
			}
			if z := max(y, x); z != y {
				errorf("max(%v, %v) = %v, want %v", y, x, z, y)
			}
		}
	}
}

func TestMinMaxInt()    { testMinMax[int](-7, 0, 9) }
func TestMinMaxUint8()  { testMinMax[uint8](0, 1, 2, 4, 7) }
func TestMinMaxString() { testMinMax[string]("a", "b", "c") }


================================================
FILE: go/ssa/interp/testdata/mrvchain.go
================================================
// Tests of call chaining f(g()) when g has multiple return values (MRVs).
// See https://code.google.com/p/go/issues/detail?id=4573.

package main

func assert(actual, expected int) {
	if actual != expected {
		panic(actual)
	}
}

func g() (int, int) {
	return 5, 7
}

func g2() (float64, float64) {
	return 5, 7
}

func f1v(x int, v ...int) {
	assert(x, 5)
	assert(v[0], 7)
}

func f2(x, y int) {
	assert(x, 5)
	assert(y, 7)
}

func f2v(x, y int, v ...int) {
	assert(x, 5)
	assert(y, 7)
	assert(len(v), 0)
}

func complexArgs() (float64, float64) {
	return 5, 7
}

func appendArgs() ([]string, string) {
	return []string{"foo"}, "bar"
}

func h() (i interface{}, ok bool) {
	m := map[int]string{1: "hi"}
	i, ok = m[1] // string->interface{} conversion within multi-valued expression
	return
}

func h2() (i interface{}, ok bool) {
	ch := make(chan string, 1)
	ch <- "hi"
	i, ok = <-ch // string->interface{} conversion within multi-valued expression
	return
}

func main() {
	f1v(g())
	f2(g())
	f2v(g())
	if c := complex(complexArgs()); c != 5+7i {
		panic(c)
	}
	if s := append(appendArgs()); len(s) != 2 || s[0] != "foo" || s[1] != "bar" {
		panic(s)
	}
	i, ok := h()
	if !ok || i.(string) != "hi" {
		panic(i)
	}
	i, ok = h2()
	if !ok || i.(string) != "hi" {
		panic(i)
	}
}


================================================
FILE: go/ssa/interp/testdata/newexpr_go126.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.26

package main

func main() {
	// Test new(expr), introduced in go1.26.
	var ptr *int = new(123)
	if *ptr != 123 {
		panic("wrong value")
	}
}


================================================
FILE: go/ssa/interp/testdata/range.go
================================================
package main

// Tests of range loops.

import "fmt"

// Range over string.
func init() {
	if x := len("Hello, 世界"); x != 13 { // bytes
		panic(x)
	}
	var indices []int
	var runes []rune
	for i, r := range "Hello, 世界" {
		runes = append(runes, r)
		indices = append(indices, i)
	}
	if x := fmt.Sprint(runes); x != "[72 101 108 108 111 44 32 19990 30028]" {
		panic(x)
	}
	if x := fmt.Sprint(indices); x != "[0 1 2 3 4 5 6 7 10]" {
		panic(x)
	}
	s := ""
	for _, r := range runes {
		s += string(r)
	}
	if s != "Hello, 世界" {
		panic(s)
	}

	var x int
	for range "Hello, 世界" {
		x++
	}
	if x != len(indices) {
		panic(x)
	}
}

// Regression test for range of pointer to named array type.
func init() {
	type intarr [3]int
	ia := intarr{1, 2, 3}
	var count int
	for _, x := range &ia {
		count += x
	}
	if count != 6 {
		panic(count)
	}
}

func main() {
}


================================================
FILE: go/ssa/interp/testdata/rangefunc.go
================================================
// Range over functions.

// Currently requires 1.22 and GOEXPERIMENT=rangefunc.

// Fork of src/cmd/compile/internal/rangefunc/rangefunc_test.go

package main

import (
	"fmt"
	"strings"
)

func main() {
	TestCheck("TestCheck")
	TestCooperativeBadOfSliceIndex("TestCooperativeBadOfSliceIndex")
	TestCooperativeBadOfSliceIndexCheck("TestCooperativeBadOfSliceIndexCheck")
	TestTrickyIterAll("TestTrickyIterAll")
	TestTrickyIterOne("TestTrickyIterOne")
	TestTrickyIterZero("TestTrickyIterZero")
	TestTrickyIterZeroCheck("TestTrickyIterZeroCheck")
	TestTrickyIterEcho("TestTrickyIterEcho")
	TestTrickyIterEcho2("TestTrickyIterEcho2")
	TestBreak1("TestBreak1")
	TestBreak2("TestBreak2")
	TestContinue("TestContinue")
	TestBreak3("TestBreak3")
	TestBreak1BadA("TestBreak1BadA")
	TestBreak1BadB("TestBreak1BadB")
	TestMultiCont0("TestMultiCont0")
	TestMultiCont1("TestMultiCont1")
	TestMultiCont2("TestMultiCont2")
	TestMultiCont3("TestMultiCont3")
	TestMultiBreak0("TestMultiBreak0")
	TestMultiBreak1("TestMultiBreak1")
	TestMultiBreak2("TestMultiBreak2")
	TestMultiBreak3("TestMultiBreak3")
	TestPanickyIterator1("TestPanickyIterator1")
	TestPanickyIterator1Check("TestPanickyIterator1Check")
	TestPanickyIterator2("TestPanickyIterator2")
	TestPanickyIterator2Check("TestPanickyIterator2Check")
	TestPanickyIterator3("TestPanickyIterator3")
	TestPanickyIterator3Check("TestPanickyIterator3Check")
	TestPanickyIterator4("TestPanickyIterator4")
	TestPanickyIterator4Check("TestPanickyIterator4Check")
	TestVeryBad1("TestVeryBad1")
	TestVeryBad2("TestVeryBad2")
	TestVeryBadCheck("TestVeryBadCheck")
	TestOk("TestOk")
	TestBreak1BadDefer("TestBreak1BadDefer")
	TestReturns("TestReturns")
	TestGotoA("TestGotoA")
	TestGotoB("TestGotoB")
	TestPanicReturns("TestPanicReturns")
}

type testingT string

func (t testingT) Log(args ...any) {
	s := fmt.Sprint(args...)
	println(t, "\t", s)
}

func (t testingT) Error(args ...any) {
	s := string(t) + "\terror: " + fmt.Sprint(args...)
	panic(s)
}

// slicesEqual is a clone of slices.Equal
func slicesEqual[S ~[]E, E comparable](s1, s2 S) bool {
	if len(s1) != len(s2) {
		return false
	}
	for i := range s1 {
		if s1[i] != s2[i] {
			return false
		}
	}
	return true
}

type Seq[T any] func(yield func(T) bool)
type Seq2[T1, T2 any] func(yield func(T1, T2) bool)

// OfSliceIndex returns a Seq2 over the elements of s. It is equivalent
// to range s.
func OfSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			if !yield(i, v) {
				return
			}
		}
		return
	}
}

// BadOfSliceIndex is "bad" because it ignores the return value from yield
// and just keeps on iterating.
func BadOfSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			yield(i, v)
		}
		return
	}
}

// VeryBadOfSliceIndex is "very bad" because it ignores the return value from yield
// and just keeps on iterating, and also wraps that call in a defer-recover so it can
// keep on trying after the first panic.
func VeryBadOfSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			func() {
				defer func() {
					recover()
				}()
				yield(i, v)
			}()
		}
		return
	}
}

// SwallowPanicOfSliceIndex hides panics and converts them to normal return
func SwallowPanicOfSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			done := false
			func() {
				defer func() {
					if r := recover(); r != nil {
						done = true
					}
				}()
				done = !yield(i, v)
			}()
			if done {
				return
			}
		}
		return
	}
}

// PanickyOfSliceIndex iterates the slice but panics if it exits the loop early
func PanickyOfSliceIndex[T any, S ~[]T](s S) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			if !yield(i, v) {
				panic("Panicky iterator panicking")
			}
		}
		return
	}
}

// CooperativeBadOfSliceIndex calls the loop body from a goroutine after
// a ping on a channel, and returns recover()on that same channel.
func CooperativeBadOfSliceIndex[T any, S ~[]T](s S, proceed chan any) Seq2[int, T] {
	return func(yield func(int, T) bool) {
		for i, v := range s {
			if !yield(i, v) {
				// if the body breaks, call yield just once in a goroutine
				go func() {
					<-proceed
					defer func() {
						proceed <- recover()
					}()
					yield(0, s[0])
				}()
				return
			}
		}
		return
	}
}

// TrickyIterator is a type intended to test whether an iterator that
// calls a yield function after loop exit must inevitably escape the
// closure; this might be relevant to future checking/optimization.
type TrickyIterator struct {
	yield func(int, int) bool
}

func (ti *TrickyIterator) iterEcho(s []int) Seq2[int, int] {
	return func(yield func(int, int) bool) {
		for i, v := range s {
			if !yield(i, v) {
				ti.yield = yield
				return
			}
			if ti.yield != nil && !ti.yield(i, v) {
				return
			}
		}
		ti.yield = yield
		return
	}
}

func (ti *TrickyIterator) iterAll(s []int) Seq2[int, int] {
	return func(yield func(int, int) bool) {
		ti.yield = yield // Save yield for future abuse
		for i, v := range s {
			if !yield(i, v) {
				return
			}
		}
		return
	}
}
func (ti *TrickyIterator) iterOne(s []int) Seq2[int, int] {
	return func(yield func(int, int) bool) {
		ti.yield = yield // Save yield for future abuse
		if len(s) > 0 {  // Not in a loop might escape differently
			yield(0, s[0])
		}
		return
	}
}
func (ti *TrickyIterator) iterZero(s []int) Seq2[int, int] {
	return func(yield func(int, int) bool) {
		ti.yield = yield // Save yield for future abuse
		// Don't call it at all, maybe it won't escape
		return
	}
}
func (ti *TrickyIterator) fail() {
	if ti.yield != nil {
		ti.yield(1, 1)
	}
}

func matchError(r any, x string) bool {
	if r == nil {
		return false
	}
	if x == "" {
		return true
	}
	switch p := r.(type) {
	case string:
		return p == x
	case errorString:
		return p.Error() == x
	case error:
		return strings.Contains(p.Error(), x)
	}
	return false
}

func matchErrorHelper(t testingT, r any, x string) {
	if matchError(r, x) {
		t.Log("Saw expected panic: ", r)
	} else {
		t.Error("Saw wrong panic: '", r, "' . expected '", x, "'")
	}
}

const DONE = 0          // body of loop has exited in a non-panic way
const READY = 1         // body of loop has not exited yet, is not running
const PANIC = 2         // body of loop is either currently running, or has panicked
const EXHAUSTED = 3     // iterator function return, i.e., sequence is "exhausted"
const MISSING_PANIC = 4 // overload "READY" for panic call

// An errorString represents a runtime error described by a single string.
type errorString string

func (e errorString) Error() string {
	return string(e)
}

const (
	// RERR_ is for runtime error, and may be regexps/substrings, to simplify use of tests with tools
	RERR_DONE      = "yield function called after range loop exit"
	RERR_PANIC     = "range function continued iteration after loop body panic"
	RERR_EXHAUSTED = "yield function called after range loop exit" // ssa does not distinguish DONE and EXHAUSTED
	RERR_MISSING   = "iterator call did not preserve panic"

	// CERR_ is for checked errors in the Check combinator defined above, and should be literal strings
	CERR_PFX       = "checked rangefunc error: "
	CERR_DONE      = CERR_PFX + "loop iteration after body done"
	CERR_PANIC     = CERR_PFX + "loop iteration after panic"
	CERR_EXHAUSTED = CERR_PFX + "loop iteration after iterator exit"
	CERR_MISSING   = CERR_PFX + "loop iterator swallowed panic"
)

var fail []error = []error{
	errorString(CERR_DONE),
	errorString(CERR_PFX + "loop iterator, unexpected error"),
	errorString(CERR_PANIC),
	errorString(CERR_EXHAUSTED),
	errorString(CERR_MISSING),
}

// Check wraps the function body passed to iterator forall
// in code that ensures that it cannot (successfully) be called
// either after body return false (control flow out of loop) or
// forall itself returns (the iteration is now done).
//
// Note that this can catch errors before the inserted checks.
func Check[U, V any](forall Seq2[U, V]) Seq2[U, V] {
	return func(body func(U, V) bool) {
		state := READY
		forall(func(u U, v V) bool {
			if state != READY {
				panic(fail[state])
			}
			state = PANIC
			ret := body(u, v)
			if ret {
				state = READY
			} else {
				state = DONE
			}
			return ret
		})
		if state == PANIC {
			panic(fail[MISSING_PANIC])
		}
		state = EXHAUSTED
	}
}

func TestCheck(t testingT) {
	i := 0
	defer func() {
		t.Log("i = ", i) // 45
		matchErrorHelper(t, recover(), CERR_DONE)
	}()
	for _, x := range Check(BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})) {
		i += x
		if i > 4*9 {
			break
		}
	}
}

func TestCooperativeBadOfSliceIndex(t testingT) {
	i := 0
	proceed := make(chan any)
	for _, x := range CooperativeBadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, proceed) {
		i += x
		if i >= 36 {
			break
		}
	}
	proceed <- true
	r := <-proceed
	matchErrorHelper(t, r, RERR_EXHAUSTED)
	if i != 36 {
		t.Error("Expected i == 36, saw ", i, "instead")
	} else {
		t.Log("i = ", i)
	}
}

func TestCooperativeBadOfSliceIndexCheck(t testingT) {
	i := 0
	proceed := make(chan any)
	for _, x := range Check(CooperativeBadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}, proceed)) {
		i += x
		if i >= 36 {
			break
		}
	}
	proceed <- true
	r := <-proceed
	matchErrorHelper(t, r, CERR_EXHAUSTED)

	if i != 36 {
		t.Error("Expected i == 36, saw ", i, "instead")
	} else {
		t.Log("i = ", i)
	}
}

func TestTrickyIterAll(t testingT) {
	trickItAll := TrickyIterator{}
	i := 0
	for _, x := range trickItAll.iterAll([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
		i += x
		if i >= 36 {
			break
		}
	}
	if i != 36 {
		t.Error("Expected i == 36, saw ", i, " instead")
	} else {
		t.Log("i = ", i)
	}
	defer func() {
		matchErrorHelper(t, recover(), RERR_EXHAUSTED)
	}()
	trickItAll.fail()
}

func TestTrickyIterOne(t testingT) {
	trickItOne := TrickyIterator{}
	i := 0
	for _, x := range trickItOne.iterOne([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
		i += x
		if i >= 36 {
			break
		}
	}
	if i != 1 {
		t.Error("Expected i == 1, saw ", i, " instead")
	} else {
		t.Log("i = ", i)
	}
	defer func() {
		matchErrorHelper(t, recover(), RERR_EXHAUSTED)
	}()
	trickItOne.fail()
}

func TestTrickyIterZero(t testingT) {
	trickItZero := TrickyIterator{}
	i := 0
	for _, x := range trickItZero.iterZero([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
		i += x
		if i >= 36 {
			break
		}
	}
	// Don't care about value, ought to be 0 anyhow.
	t.Log("i = ", i)
	defer func() {
		matchErrorHelper(t, recover(), RERR_EXHAUSTED)
	}()
	trickItZero.fail()
}

func TestTrickyIterZeroCheck(t testingT) {
	trickItZero := TrickyIterator{}
	i := 0
	for _, x := range Check(trickItZero.iterZero([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10})) {
		i += x
		if i >= 36 {
			break
		}
	}
	// Don't care about value, ought to be 0 anyhow.
	t.Log("i = ", i)
	defer func() {
		matchErrorHelper(t, recover(), CERR_EXHAUSTED)
	}()
	trickItZero.fail()
}

func TestTrickyIterEcho(t testingT) {
	trickItAll := TrickyIterator{}
	i := 0
	for _, x := range trickItAll.iterAll([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
		t.Log("first loop i=", i)
		i += x
		if i >= 10 {
			break
		}
	}

	if i != 10 {
		t.Error("Expected i == 10, saw", i, "instead")
	} else {
		t.Log("i = ", i)
	}

	defer func() {
		matchErrorHelper(t, recover(), RERR_EXHAUSTED)
		t.Log("end i=", i)
	}()

	i = 0
	for _, x := range trickItAll.iterEcho([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
		t.Log("second loop i=", i)
		if x >= 5 {
			break
		}
	}

}

func TestTrickyIterEcho2(t testingT) {
	trickItAll := TrickyIterator{}
	var i int

	defer func() {
		matchErrorHelper(t, recover(), RERR_EXHAUSTED)
		t.Log("end i=", i)
	}()

	for k := range 2 {
		i = 0
		for _, x := range trickItAll.iterEcho([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			t.Log("k=", k, ",x=", x, ",i=", i)
			i += x
			if i >= 10 {
				break
			}
		}
		t.Log("i = ", i)

		if i != 10 {
			t.Error("Expected i == 10, saw ", i, "instead")
		}
	}
}

// TestBreak1 should just work, with well-behaved iterators.
// (The misbehaving iterator detector should not trigger.)
func TestBreak1(t testingT) {
	var result []int
	var expect = []int{1, 2, -1, 1, 2, -2, 1, 2, -3}
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4}) {
		if x == -4 {
			break
		}
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				break
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, " got ", result)
	}
}

// TestBreak2 should just work, with well-behaved iterators.
// (The misbehaving iterator detector should not trigger.)
func TestBreak2(t testingT) {
	var result []int
	var expect = []int{1, 2, -1, 1, 2, -2, 1, 2, -3}
outer:
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4}) {
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				break
			}
			if x == -4 {
				break outer
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got ", result)
	}
}

// TestContinue should just work, with well-behaved iterators.
// (The misbehaving iterator detector should not trigger.)
func TestContinue(t testingT) {
	var result []int
	var expect = []int{-1, 1, 2, -2, 1, 2, -3, 1, 2, -4}
outer:
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4}) {
		result = append(result, x)
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				continue outer
			}
			if x == -4 {
				break outer
			}
			result = append(result, y)
		}
		result = append(result, x-10)
	}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got ", result)
	}
}

// TestBreak3 should just work, with well-behaved iterators.
// (The misbehaving iterator detector should not trigger.)
func TestBreak3(t testingT) {
	var result []int
	var expect = []int{100, 10, 2, 4, 200, 10, 2, 4, 20, 2, 4, 300, 10, 2, 4, 20, 2, 4, 30}
X:
	for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
	Y:
		for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
			if 10*y >= x {
				break
			}
			result = append(result, y)
			if y == 30 {
				continue X
			}
		Z:
			for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
				if z&1 == 1 {
					continue Z
				}
				result = append(result, z)
				if z >= 4 {
					continue Y
				}
			}
			result = append(result, -y) // should never be executed
		}
		result = append(result, x)
	}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got ", result)
	}
}

// TestBreak1BadA should end in a panic when the outer-loop's
// single-level break is ignore by BadOfSliceIndex
func TestBreak1BadA(t testingT) {
	var result []int
	var expect = []int{1, 2, -1, 1, 2, -2, 1, 2, -3}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range BadOfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		if x == -4 {
			break
		}
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				break
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
}

// TestBreak1BadB should end in a panic, sooner, when the inner-loop's
// (nested) single-level break is ignored by BadOfSliceIndex
func TestBreak1BadB(t testingT) {
	var result []int
	var expect = []int{1, 2} // inner breaks, panics, after before outer appends
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		if x == -4 {
			break
		}
		for _, y := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				break
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
}

// TestMultiCont0 tests multilevel continue with no bad iterators
// (it should just work)
func TestMultiCont0(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4, 2000}
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						continue W // modified to be multilevel
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got %v", expect, result)
	}
}

// TestMultiCont1 tests multilevel continue with a bad iterator
// in the outermost loop exited by the continue.
func TestMultiCont1(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range BadOfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						continue W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiCont2 tests multilevel continue with a bad iterator
// in a middle loop exited by the continue.
func TestMultiCont2(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range BadOfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						continue W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiCont3 tests multilevel continue with a bad iterator
// in the innermost loop exited by the continue.
func TestMultiCont3(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						continue W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiBreak0 tests multilevel break with a bad iterator
// in the outermost loop exited by the break (the outermost loop).
func TestMultiBreak0(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range BadOfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						break W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiBreak1 tests multilevel break with a bad iterator
// in an intermediate loop exited by the break.
func TestMultiBreak1(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range BadOfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						break W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiBreak2 tests multilevel break with two bad iterators
// in intermediate loops exited by the break.
func TestMultiBreak2(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range BadOfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range BadOfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						break W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestMultiBreak3 tests multilevel break with the bad iterator
// in the innermost loop exited by the break.
func TestMultiBreak3(t testingT) {
	var result []int
	var expect = []int{1000, 10, 2, 4}
	defer func() {
		t.Log(result)
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got", result)
		}
	}()
W:
	for _, w := range OfSliceIndex([]int{1000, 2000}) {
		result = append(result, w)
		if w == 2000 {
			break
		}
		for _, x := range OfSliceIndex([]int{100, 200, 300, 400}) {
			for _, y := range OfSliceIndex([]int{10, 20, 30, 40}) {
				result = append(result, y)
				for _, z := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
					if z&1 == 1 {
						continue
					}
					result = append(result, z)
					if z >= 4 {
						break W
					}
				}
				result = append(result, -y) // should never be executed
			}
			result = append(result, x)
		}
	}
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

func TestPanickyIterator1(t testingT) {
	var result []int
	var expect = []int{1, 2, 3, 4}
	defer func() {
		matchErrorHelper(t, recover(), "Panicky iterator panicking")
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, z := range PanickyOfSliceIndex([]int{1, 2, 3, 4}) {
		result = append(result, z)
		if z == 4 {
			break
		}
	}
}

func TestPanickyIterator1Check(t testingT) {
	var result []int
	var expect = []int{1, 2, 3, 4}
	defer func() {
		matchErrorHelper(t, recover(), "Panicky iterator panicking")
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, z := range Check(PanickyOfSliceIndex([]int{1, 2, 3, 4})) {
		result = append(result, z)
		if z == 4 {
			break
		}
	}
}

func TestPanickyIterator2(t testingT) {
	var result []int
	var expect = []int{100, 10, 1, 2}
	defer func() {
		matchErrorHelper(t, recover(), RERR_MISSING)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range OfSliceIndex([]int{100, 200}) {
		result = append(result, x)
	Y:
		// swallows panics and iterates to end BUT `break Y` disables the body, so--> 10, 1, 2
		for _, y := range VeryBadOfSliceIndex([]int{10, 20}) {
			result = append(result, y)

			// converts early exit into a panic --> 1, 2
			for k, z := range PanickyOfSliceIndex([]int{1, 2}) { // iterator panics
				result = append(result, z)
				if k == 1 {
					break Y
				}
			}
		}
	}
}

func TestPanickyIterator2Check(t testingT) {
	var result []int
	var expect = []int{100, 10, 1, 2}
	defer func() {
		matchErrorHelper(t, recover(), CERR_MISSING)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range Check(OfSliceIndex([]int{100, 200})) {
		result = append(result, x)
	Y:
		// swallows panics and iterates to end BUT `break Y` disables the body, so--> 10, 1, 2
		for _, y := range Check(VeryBadOfSliceIndex([]int{10, 20})) {
			result = append(result, y)

			// converts early exit into a panic --> 1, 2
			for k, z := range Check(PanickyOfSliceIndex([]int{1, 2})) { // iterator panics
				result = append(result, z)
				if k == 1 {
					break Y
				}
			}
		}
	}
}

func TestPanickyIterator3(t testingT) {
	var result []int
	var expect = []int{100, 10, 1, 2, 200, 10, 1, 2}
	defer func() {
		if r := recover(); r != nil {
			t.Error("Unexpected panic ", r)
		}
		t.Log(result)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range OfSliceIndex([]int{100, 200}) {
		result = append(result, x)
	Y:
		// swallows panics and iterates to end BUT `break Y` disables the body, so--> 10, 1, 2
		// This is cross-checked against the checked iterator below; the combinator should behave the same.
		for _, y := range VeryBadOfSliceIndex([]int{10, 20}) {
			result = append(result, y)

			for k, z := range OfSliceIndex([]int{1, 2}) { // iterator does not panic
				result = append(result, z)
				if k == 1 {
					break Y
				}
			}
		}
	}
}
func TestPanickyIterator3Check(t testingT) {
	var result []int
	var expect = []int{100, 10, 1, 2, 200, 10, 1, 2}
	defer func() {
		if r := recover(); r != nil {
			t.Error("Unexpected panic ", r)
		}
		t.Log(result)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range Check(OfSliceIndex([]int{100, 200})) {
		result = append(result, x)
	Y:
		// swallows panics and iterates to end BUT `break Y` disables the body, so--> 10, 1, 2
		for _, y := range Check(VeryBadOfSliceIndex([]int{10, 20})) {
			result = append(result, y)

			for k, z := range Check(OfSliceIndex([]int{1, 2})) { // iterator does not panic
				result = append(result, z)
				if k == 1 {
					break Y
				}
			}
		}
	}
}

func TestPanickyIterator4(t testingT) {
	var result []int
	var expect = []int{1, 2, 3}
	defer func() {
		matchErrorHelper(t, recover(), RERR_MISSING)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range SwallowPanicOfSliceIndex([]int{1, 2, 3, 4}) {
		result = append(result, x)
		if x == 3 {
			panic("x is 3")
		}
	}

}

func TestPanickyIterator4Check(t testingT) {
	var result []int
	var expect = []int{1, 2, 3}
	defer func() {
		matchErrorHelper(t, recover(), CERR_MISSING)
		if !slicesEqual(expect, result) {
			t.Error("Expected ", expect, ", got ", result)
		}
	}()
	for _, x := range Check(SwallowPanicOfSliceIndex([]int{1, 2, 3, 4})) {
		result = append(result, x)
		if x == 3 {
			panic("x is 3")
		}
	}

}

// veryBad tests that a loop nest behaves sensibly in the face of a
// "very bad" iterator.  In this case, "sensibly" means that the
// break out of X still occurs after the very bad iterator finally
// quits running (the control flow bread crumbs remain.)
func veryBad(s []int) []int {
	var result []int
X:
	for _, x := range OfSliceIndex([]int{1, 2, 3}) {
		result = append(result, x)
		for _, y := range VeryBadOfSliceIndex(s) {
			result = append(result, y)
			break X
		}
		for _, z := range OfSliceIndex([]int{100, 200, 300}) {
			result = append(result, z)
			if z == 100 {
				break
			}
		}
	}
	return result
}

// veryBadCheck wraps a "very bad" iterator with Check,
// demonstrating that the very bad iterator also hides panics
// thrown by Check.
func veryBadCheck(s []int) []int {
	var result []int
X:
	for _, x := range OfSliceIndex([]int{1, 2, 3}) {
		result = append(result, x)
		for _, y := range Check(VeryBadOfSliceIndex(s)) {
			result = append(result, y)
			break X
		}
		for _, z := range OfSliceIndex([]int{100, 200, 300}) {
			result = append(result, z)
			if z == 100 {
				break
			}
		}
	}
	return result
}

// okay is the not-bad version of veryBad.
// They should behave the same.
func okay(s []int) []int {
	var result []int
X:
	for _, x := range OfSliceIndex([]int{1, 2, 3}) {
		result = append(result, x)
		for _, y := range OfSliceIndex(s) {
			result = append(result, y)
			break X
		}
		for _, z := range OfSliceIndex([]int{100, 200, 300}) {
			result = append(result, z)
			if z == 100 {
				break
			}
		}
	}
	return result
}

// TestVeryBad1 checks the behavior of an extremely poorly behaved iterator.
func TestVeryBad1(t testingT) {
	result := veryBad([]int{10, 20, 30, 40, 50}) // odd length
	expect := []int{1, 10}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestVeryBad2 checks the behavior of an extremely poorly behaved iterator.
func TestVeryBad2(t testingT) {
	result := veryBad([]int{10, 20, 30, 40}) // even length
	expect := []int{1, 10}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestVeryBadCheck checks the behavior of an extremely poorly behaved iterator,
// which also suppresses the exceptions from "Check"
func TestVeryBadCheck(t testingT) {
	result := veryBadCheck([]int{10, 20, 30, 40}) // even length
	expect := []int{1, 10}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// TestOk is the nice version of the very bad iterator.
func TestOk(t testingT) {
	result := okay([]int{10, 20, 30, 40, 50}) // odd length
	expect := []int{1, 10}
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
}

// testBreak1BadDefer checks that defer behaves properly even in
// the presence of loop bodies panicking out of bad iterators.
// (i.e., the instrumentation did not break defer in these loops)
func testBreak1BadDefer(t testingT) (result []int) {
	var expect = []int{1, 2, -1, 1, 2, -2, 1, 2, -3, -30, -20, -10}
	defer func() {
		matchErrorHelper(t, recover(), RERR_DONE)
		if !slicesEqual(expect, result) {
			t.Error("(Inner) Expected ", expect, ", got", result)
		}
	}()
	for _, x := range BadOfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				break
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	return
}

func TestBreak1BadDefer(t testingT) {
	var result []int
	var expect = []int{1, 2, -1, 1, 2, -2, 1, 2, -3, -30, -20, -10}
	result = testBreak1BadDefer(t)
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("(Outer) Expected ", expect, ", got ", result)
	}
}

// testReturn1 has no bad iterators.
func testReturn1() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				return
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	return
}

// testReturn2 has an outermost bad iterator
func testReturn2() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range BadOfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				return
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	return
}

// testReturn3 has an innermost bad iterator
func testReturn3() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				return
			}
			result = append(result, y)
		}
	}
	return
}

// testReturn4 has no bad iterators, but exercises  return variable rewriting
// differs from testReturn1 because deferred append to "result" does not change
// the return value in this case.
func testReturn4(t testingT) (_ []int, _ []int, err any) {
	var result []int
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				return result, result, nil
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
	return
}

// TestReturns checks that returns through bad iterators behave properly,
// for inner and outer bad iterators.
func TestReturns(t testingT) {
	var result []int
	var result2 []int
	var expect = []int{-1, 1, 2, -10}
	var expect2 = []int{-1, 1, 2}
	var err any
	result, err = testReturn1()
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err != nil {
		t.Error("Unexpected error: ", err)
	}
	result, err = testReturn2()
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}
	result, err = testReturn3()
	t.Log(result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}

	result, result2, err = testReturn4(t)
	if !slicesEqual(expect2, result) {
		t.Error("Expected ", expect2, "got", result)
	}
	if !slicesEqual(expect2, result2) {
		t.Error("Expected ", expect2, "got", result2)
	}
	if err != nil {
		t.Error("Unexpected error ", err)
	}
}

// testGotoA1 tests loop-nest-internal goto, no bad iterators.
func testGotoA1() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto A
			}
			result = append(result, y)
		}
		result = append(result, x)
	A:
	}
	return
}

// testGotoA2 tests loop-nest-internal goto, outer bad iterator.
func testGotoA2() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range BadOfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto A
			}
			result = append(result, y)
		}
		result = append(result, x)
	A:
	}
	return
}

// testGotoA3 tests loop-nest-internal goto, inner bad iterator.
func testGotoA3() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto A
			}
			result = append(result, y)
		}
		result = append(result, x)
	A:
	}
	return
}
func TestGotoA(t testingT) {
	var result []int
	var expect = []int{-1, 1, 2, -2, 1, 2, -3, 1, 2, -4, -30, -20, -10}
	var expect3 = []int{-1, 1, 2, -10} // first goto becomes a panic
	var err any
	result, err = testGotoA1()
	t.Log("testGotoA1", result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err != nil {
		t.Error("Unexpected error: ", err)
	}
	result, err = testGotoA2()
	t.Log("testGotoA2", result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}
	result, err = testGotoA3()
	t.Log("testGotoA3", result)
	if !slicesEqual(expect3, result) {
		t.Error("Expected %v, got %v", expect3, result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}
}

// testGotoB1 tests loop-nest-exiting goto, no bad iterators.
func testGotoB1() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto B
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
B:
	result = append(result, 999)
	return
}

// testGotoB2 tests loop-nest-exiting goto, outer bad iterator.
func testGotoB2() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range BadOfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range OfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto B
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
B:
	result = append(result, 999)
	return
}

// testGotoB3 tests loop-nest-exiting goto, inner bad iterator.
func testGotoB3() (result []int, err any) {
	defer func() {
		err = recover()
	}()
	for _, x := range OfSliceIndex([]int{-1, -2, -3, -4, -5}) {
		result = append(result, x)
		if x == -4 {
			break
		}
		defer func() {
			result = append(result, x*10)
		}()
		for _, y := range BadOfSliceIndex([]int{1, 2, 3, 4, 5, 6, 7, 8, 9, 10}) {
			if y == 3 {
				goto B
			}
			result = append(result, y)
		}
		result = append(result, x)
	}
B:
	result = append(result, 999)
	return
}

func TestGotoB(t testingT) {
	var result []int
	var expect = []int{-1, 1, 2, 999, -10}
	var expectX = []int{-1, 1, 2, -10}
	var err any
	result, err = testGotoB1()
	t.Log("testGotoB1", result)
	if !slicesEqual(expect, result) {
		t.Error("Expected ", expect, ", got", result)
	}
	if err != nil {
		t.Error("Unexpected error: ", err)
	}
	result, err = testGotoB2()
	t.Log("testGotoB2", result)
	if !slicesEqual(expectX, result) {
		t.Error("Expected %v, got %v", expectX, result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}

	result, err = testGotoB3()
	t.Log("testGotoB3", result)
	if !slicesEqual(expectX, result) {
		t.Error("Expected %v, got %v", expectX, result)
	}
	if err == nil {
		t.Error("Missing expected error")
	} else {
		matchErrorHelper(t, err, RERR_DONE)
	}
}

// once returns an iterator that runs its loop body once with the supplied value
func once[T any](x T) Seq[T] {
	return func(yield func(T) bool) {
		yield(x)
	}
}

// terrify converts an iterator into one that panics with the supplied string
// if/when the loop body terminates early (returns false, for break, goto, outer
// continue, or return).
func terrify[T any](s string, forall Seq[T]) Seq[T] {
	return func(yield func(T) bool) {
		forall(func(v T) bool {
			if !yield(v) {
				panic(s)
			}
			return true
		})
	}
}

func use[T any](T) {
}

// f runs a not-rangefunc iterator that recovers from a panic that follows execution of a return.
// what does f return?
func f() string {
	defer func() { recover() }()
	defer panic("f panic")
	for _, s := range []string{"f return"} {
		return s
	}
	return "f not reached"
}

// g runs a rangefunc iterator that recovers from a panic that follows execution of a return.
// what does g return?
func g() string {
	defer func() { recover() }()
	for s := range terrify("g panic", once("g return")) {
		return s
	}
	return "g not reached"
}

// h runs a rangefunc iterator that recovers from a panic that follows execution of a return.
// the panic occurs in the rangefunc iterator itself.
// what does h return?
func h() (hashS string) {
	defer func() { recover() }()
	for s := range terrify("h panic", once("h return")) {
		hashS := s
		use(hashS)
		return s
	}
	return "h not reached"
}

func j() (hashS string) {
	defer func() { recover() }()
	for s := range terrify("j panic", once("j return")) {
		hashS = s
		return
	}
	return "j not reached"
}

// k runs a rangefunc iterator that recovers from a panic that follows execution of a return.
// the panic occurs in the rangefunc iterator itself.
// k includes an additional mechanism to for making the return happen
// what does k return?
func k() (hashS string) {
	_return := func(s string) { hashS = s }

	defer func() { recover() }()
	for s := range terrify("k panic", once("k return")) {
		_return(s)
		return
	}
	return "k not reached"
}

func m() (hashS string) {
	_return := func(s string) { hashS = s }

	defer func() { recover() }()
	for s := range terrify("m panic", once("m return")) {
		defer _return(s)
		return s + ", but should be replaced in a defer"
	}
	return "m not reached"
}

func n() string {
	defer func() { recover() }()
	for s := range terrify("n panic", once("n return")) {
		return s + func(s string) string {
			defer func() { recover() }()
			for s := range terrify("n closure panic", once(s)) {
				return s
			}
			return "n closure not reached"
		}(" and n closure return")
	}
	return "n not reached"
}

type terrifyTestCase struct {
	f func() string
	e string
}

func TestPanicReturns(t testingT) {
	tcs := []terrifyTestCase{
		{f, "f return"},
		{g, "g return"},
		{h, "h return"},
		{k, "k return"},
		{j, "j return"},
		{m, "m return"},
		{n, "n return and n closure return"},
	}

	for _, tc := range tcs {
		got := tc.f()
		if got != tc.e {
			t.Error("Got '", got, "' expected ", tc.e)
		} else {
			t.Log("Got expected '", got, "'")
		}
	}
}


================================================
FILE: go/ssa/interp/testdata/rangeoverint.go
================================================
package main

// Range over integers (Go 1.22).

import "fmt"

func f() {
	s := "AB"
	for range 5 {
		s += s
	}
	if s != "ABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABABAB" {
		panic(s)
	}

	var t []int
	for i := range 10 {
		t = append(t, i)
	}
	if got, want := fmt.Sprint(t), "[0 1 2 3 4 5 6 7 8 9]"; got != want {
		panic(got)
	}

	var u []uint
	for i := range uint(3) {
		u = append(u, i)
	}
	if got, want := fmt.Sprint(u), "[0 1 2]"; got != want {
		panic(got)
	}

	for i := range 0 {
		panic(i)
	}

	for i := range int(-1) {
		panic(i)
	}

	for _, test := range []struct {
		x    int
		b, c bool
		want string
	}{
		{-1, false, false, "[-123 -123]"},
		{0, false, false, "[-123 -123]"},
		{1, false, false, "[-123 0 333 333]"},
		{2, false, false, "[-123 0 333 1 333 333]"},
		{2, false, true, "[-123 0 222 1 222 222]"},
		{2, true, false, "[-123 0 111 111]"},
		{3, false, false, "[-123 0 333 1 333 2 333 333]"},
	} {
		got := fmt.Sprint(valueSequence(test.x, test.b, test.c))
		if got != test.want {
			panic(fmt.Sprint(test, got))
		}
	}
}

// valueSequence returns a sequence of the values of i.
// b causes an early break and c causes a continue.
func valueSequence(x int, b, c bool) []int {
	var vals []int
	var i int = -123
	vals = append(vals, i)
	for i = range x {
		vals = append(vals, i)
		if b {
			i = 111
			vals = append(vals, i)
			break
		} else if c {
			i = 222
			vals = append(vals, i)
			continue
		}
		i = 333
		vals = append(vals, i)
	}
	vals = append(vals, i)
	return vals
}

func main() { f() }


================================================
FILE: go/ssa/interp/testdata/rangevarlifetime_go122.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.22

package main

func main() {
	test_init()

	// Clones from cmd/compile/internal/loopvar/testdata .
	range_esc_address()
	range_esc_closure()
	range_esc_method()
}

// After go1.22, each i will have a distinct address.
var distinct = func(a [3]int) []*int {
	var r []*int
	for i := range a {
		r = append(r, &i)
	}
	return r
}([3]int{})

func test_init() {
	if len(distinct) != 3 {
		panic(distinct)
	}
	for i := 0; i < 3; i++ {
		if i != *(distinct[i]) {
			panic(distinct)
		}
	}
}

func range_esc_address() {
	// Clone of range_esc_address.go
	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

	sum := 0
	var is []*int
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, &i)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw ", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, pi := range is {
		sum += *pi
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected", 20, ", saw", sum)
		bug = true
	}
	if bug {
		panic("range_esc_address")
	}
}

func range_esc_closure() {
	// Clone of range_esc_closure.go
	var ints = []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
	var is []func() int

	sum := 0
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, func() int {
				if i%17 == 15 {
					i++
				}
				return i
			})
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, f := range is {
		sum += f()
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected ", 20, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("range_esc_closure")
	}
}

type I int

func (x *I) method() int {
	return int(*x)
}

func range_esc_method() {
	// Clone of range_esc_method.go
	var ints = []I{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

	sum := 0
	var is []func() int
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if int(i) == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, i.method)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, m := range is {
		sum += m()
	}
	if sum != 0+2+4+6+8 {
		println("wrong sum, expected ", 20, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("range_esc_method")
	}
}


================================================
FILE: go/ssa/interp/testdata/rangevarlifetime_old.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.21

// goversion can be pinned to anything strictly before 1.22.

package main

func main() {
	test_init()

	// Clones from cmd/compile/internal/loopvar/testdata .
	range_esc_address()
	range_esc_closure()
	range_esc_method()
}

// pre-go1.22 all of i will have the same address.
var same = func(a [3]int) []*int {
	var r []*int
	for i := range a {
		r = append(r, &i)
	}
	return r
}([3]int{})

func test_init() {
	if len(same) != 3 {
		panic(same)
	}
	for i := range same {
		for j := range same {
			if !(same[i] == same[j]) {
				panic(same)
			}
		}
	}
	for i := range same {
		if *(same[i]) != 2 {
			panic(same)
		}
	}
}

func range_esc_address() {
	// Clone of range_esc_address.go
	ints := []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

	sum := 0
	var is []*int
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, &i)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw ", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, pi := range is {
		sum += *pi
	}
	if sum != 9+9+9+9+9 {
		println("wrong sum, expected", 45, ", saw", sum)
		bug = true
	}
	if bug {
		panic("range_esc_address")
	}
}

func range_esc_closure() {
	// Clone of range_esc_closure.go
	var ints = []int{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}
	var is []func() int

	sum := 0
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if i == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, func() int {
				if i%17 == 15 {
					i++
				}
				return i
			})
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, f := range is {
		sum += f()
	}
	if sum != 9+9+9+9+9 {
		println("wrong sum, expected ", 45, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("range_esc_closure")
	}
}

type I int

func (x *I) method() int {
	return int(*x)
}

func range_esc_method() {
	// Clone of range_esc_method.go
	var ints = []I{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}

	sum := 0
	var is []func() int
	for _, i := range ints {
		for j := 0; j < 10; j++ {
			if int(i) == j { // 10 skips
				continue
			}
			sum++
		}
		if i&1 == 0 {
			is = append(is, i.method)
		}
	}

	bug := false
	if sum != 100-10 {
		println("wrong sum, expected", 90, ", saw", sum)
		bug = true
	}
	if len(is) != 5 {
		println("wrong iterations, expected ", 5, ", saw", len(is))
		bug = true
	}
	sum = 0
	for _, m := range is {
		sum += m()
	}
	if sum != 9+9+9+9+9 {
		println("wrong sum, expected ", 45, ", saw ", sum)
		bug = true
	}
	if bug {
		panic("range_esc_method")
	}
}


================================================
FILE: go/ssa/interp/testdata/recover.go
================================================
package main

// Tests of panic/recover.

import "fmt"

func fortyTwo() (r int) {
	r = 42
	// The next two statements simulate a 'return' statement.
	defer func() { recover() }()
	panic(nil)
}

func zero() int {
	defer func() { recover() }()
	panic(1)
}

func zeroEmpty() (int, string) {
	defer func() { recover() }()
	panic(1)
}

func main() {
	if r := fortyTwo(); r != 42 {
		panic(r)
	}
	if r := zero(); r != 0 {
		panic(r)
	}
	if r, s := zeroEmpty(); r != 0 || s != "" {
		panic(fmt.Sprint(r, s))
	}
}


================================================
FILE: go/ssa/interp/testdata/reflect.go
================================================
package main

import "reflect"

func main() {
	// Regression test for issue 9462.
	got := reflect.SliceOf(reflect.TypeOf(byte(0))).String()
	if got != "[]uint8" && got != "[]byte" { // result varies by toolchain
		println("BUG: " + got)
	}
}


================================================
FILE: go/ssa/interp/testdata/slice2array.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test for slice to array conversion introduced in go1.20
// See: https://tip.golang.org/ref/spec#Conversions_from_slice_to_array_pointer

package main

func main() {
	s := make([]byte, 3, 4)
	s[0], s[1], s[2] = 2, 3, 5
	a := ([2]byte)(s)
	s[0] = 7

	if a != [2]byte{2, 3} {
		panic("converted from non-nil slice to array")
	}

	{
		var s []int
		a := ([0]int)(s)
		if a != [0]int{} {
			panic("zero len array is not equal")
		}
	}

	if emptyToEmptyDoesNotPanic() {
		panic("no panic expected from emptyToEmptyDoesNotPanic()")
	}
	if !threeToFourDoesPanic() {
		panic("panic expected from threeToFourDoesPanic()")
	}

	if !fourPanicsWhileOneDoesNot[[4]int]() {
		panic("panic expected from fourPanicsWhileOneDoesNot[[4]int]()")
	}
	if fourPanicsWhileOneDoesNot[[1]int]() {
		panic("no panic expected from fourPanicsWhileOneDoesNot[[1]int]()")
	}

	if !fourPanicsWhileZeroDoesNot[[4]int]() {
		panic("panic expected from fourPanicsWhileZeroDoesNot[[4]int]()")
	}
	if fourPanicsWhileZeroDoesNot[[0]int]() {
		panic("no panic expected from fourPanicsWhileZeroDoesNot[[0]int]()")
	}
}

func emptyToEmptyDoesNotPanic() (raised bool) {
	defer func() {
		if e := recover(); e != nil {
			raised = true
		}
	}()
	var s []int
	_ = ([0]int)(s)
	return false
}

func threeToFourDoesPanic() (raised bool) {
	defer func() {
		if e := recover(); e != nil {
			raised = true
		}
	}()
	s := make([]int, 3, 5)
	_ = ([4]int)(s)
	return false
}

func fourPanicsWhileOneDoesNot[T [1]int | [4]int]() (raised bool) {
	defer func() {
		if e := recover(); e != nil {
			raised = true
		}
	}()
	s := make([]int, 3, 5)
	_ = T(s)
	return false
}

func fourPanicsWhileZeroDoesNot[T [0]int | [4]int]() (raised bool) {
	defer func() {
		if e := recover(); e != nil {
			raised = true
		}
	}()
	var s []int
	_ = T(s)
	return false
}


================================================
FILE: go/ssa/interp/testdata/slice2arrayptr.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test for slice to array pointer conversion introduced in go1.17
// See: https://tip.golang.org/ref/spec#Conversions_from_slice_to_array_pointer

package main

func main() {
	s := make([]byte, 2, 4)
	if s0 := (*[0]byte)(s); s0 == nil {
		panic("converted from non-nil slice result in nil array pointer")
	}
	if s2 := (*[2]byte)(s); &s2[0] != &s[0] {
		panic("the converted array is not slice underlying array")
	}
	wantPanic(
		func() {
			_ = (*[4]byte)(s) // panics: len([4]byte) > len(s)
		},
		"runtime error: array length is greater than slice length",
	)

	var t []string
	if t0 := (*[0]string)(t); t0 != nil {
		panic("nil slice converted to *[0]byte should be nil")
	}
	wantPanic(
		func() {
			_ = (*[1]string)(t) // panics: len([1]string) > len(t)
		},
		"runtime error: array length is greater than slice length",
	)

	f()
}

type arr [2]int

func f() {
	s := []int{1, 2, 3, 4}
	_ = *(*arr)(s)
}

func wantPanic(fn func(), s string) {
	defer func() {
		err := recover()
		if err == nil {
			panic("expected panic")
		}
		if got := err.(error).Error(); got != s {
			panic("expected panic " + s + " got " + got)
		}
	}()
	fn()
}


================================================
FILE: go/ssa/interp/testdata/src/encoding/encoding.go
================================================
package encoding

type BinaryMarshaler interface {
	MarshalBinary() (data []byte, err error)
}
type BinaryUnmarshaler interface {
	UnmarshalBinary(data []byte) error
}

type TextMarshaler interface {
	MarshalText() (text []byte, err error)
}
type TextUnmarshaler interface {
	UnmarshalText(text []byte) error
}


================================================
FILE: go/ssa/interp/testdata/src/errors/errors.go
================================================
package errors

func New(text string) error { return errorString{text} }

type errorString struct{ s string }

func (e errorString) Error() string { return e.s }


================================================
FILE: go/ssa/interp/testdata/src/fmt/fmt.go
================================================
package fmt

import (
	"errors"
	"strings"
)

func Sprint(args ...interface{}) string

func Sprintln(args ...interface{}) string {
	return Sprint(args...) + "\n"
}

func Print(args ...interface{}) (int, error) {
	var n int
	for i, arg := range args {
		if i > 0 {
			print(" ")
			n++
		}
		msg := Sprint(arg)
		n += len(msg)
		print(msg)
	}
	return n, nil
}

func Println(args ...interface{}) {
	Print(args...)
	println()
}

// formatting is too complex to fake
// handle the bare minimum needed for tests

func Printf(format string, args ...interface{}) (int, error) {
	msg := Sprintf(format, args...)
	print(msg)
	return len(msg), nil
}

func Sprintf(format string, args ...interface{}) string {
	// handle extremely simple cases that appear in tests.
	if len(format) == 0 {
		return ""
	}
	switch {
	case strings.HasPrefix("%v", format) || strings.HasPrefix("%s", format):
		return Sprint(args[0]) + Sprintf(format[2:], args[1:]...)
	case !strings.HasPrefix("%", format):
		return format[:1] + Sprintf(format[1:], args...)
	default:
		panic("unsupported format string for testing Sprintf")
	}
}

func Errorf(format string, args ...interface{}) error {
	msg := Sprintf(format, args...)
	return errors.New(msg)
}


================================================
FILE: go/ssa/interp/testdata/src/io/io.go
================================================
package io

import "errors"

var EOF = errors.New("EOF")


================================================
FILE: go/ssa/interp/testdata/src/log/log.go
================================================
package log

import (
	"fmt"
	"os"
)

func Println(v ...interface{}) {
	fmt.Println(v...)
}
func Printf(format string, v ...interface{}) {
	fmt.Printf(format, v...)
}

func Fatalln(v ...interface{}) {
	Println(v...)
	os.Exit(1)
}

func Fatalf(format string, v ...interface{}) {
	Printf(format, v...)
	os.Exit(1)
}


================================================
FILE: go/ssa/interp/testdata/src/math/math.go
================================================
package math

func Copysign(float64, float64) float64

func NaN() float64

func Inf(int) float64

func IsNaN(float64) bool

func Float64bits(float64) uint64

func Signbit(x float64) bool {
	return Float64bits(x)&(1<<63) != 0
}

func Sqrt(x float64) float64


================================================
FILE: go/ssa/interp/testdata/src/os/os.go
================================================
package os

func Getenv(string) string

func Exit(int)


================================================
FILE: go/ssa/interp/testdata/src/reflect/deepequal.go
================================================
package reflect

// Not an actual implementation of DeepEqual. This is a model that supports
// the bare minimum needed to get through testing interp.
//
// Does not handle cycles.
//
// Note: unclear if reflect.go can support this.
func DeepEqual(x, y interface{}) bool {
	if x == nil || y == nil {
		return x == y
	}
	v1 := ValueOf(x)
	v2 := ValueOf(y)

	return deepValueEqual(v1, v2, make(map[visit]bool))
}

// Key for the visitedMap in deepValueEqual.
type visit struct {
	a1, a2 uintptr
	typ    Type
}

func deepValueEqual(v1, v2 Value, visited map[visit]bool) bool {
	if !v1.IsValid() || !v2.IsValid() {
		return v1.IsValid() == v2.IsValid()
	}
	if v1.Type() != v2.Type() {
		return false
	}

	// Short circuit on reference types that can lead to cycles in comparison.
	switch v1.Kind() {
	case Pointer, Map, Slice, Interface:
		k := visit{v1.Pointer(), v2.Pointer(), v1.Type()} // Not safe for moving GC.
		if visited[k] {
			// The comparison algorithm assumes that all checks in progress are true when it reencounters them.
			return true
		}
		visited[k] = true
	}

	switch v1.Kind() {
	case Array:
		for i := 0; i < v1.Len(); i++ {
			if !deepValueEqual(v1.Index(i), v2.Index(i), visited) {
				return false
			}
		}
		return true
	case Slice:
		if v1.IsNil() != v2.IsNil() {
			return false
		}
		if v1.Len() != v2.Len() {
			return false
		}
		if v1.Pointer() == v2.Pointer() {
			return true
		}
		for i := 0; i < v1.Len(); i++ {
			if !deepValueEqual(v1.Index(i), v2.Index(i), visited) {
				return false
			}
		}
		return true
	case Interface:
		if v1.IsNil() || v2.IsNil() {
			return v1.IsNil() == v2.IsNil()
		}
		return deepValueEqual(v1.Elem(), v2.Elem(), visited)
	case Ptr:
		if v1.Pointer() == v2.Pointer() {
			return true
		}
		return deepValueEqual(v1.Elem(), v2.Elem(), visited)
	case Struct:
		for i, n := 0, v1.NumField(); i < n; i++ {
			if !deepValueEqual(v1.Field(i), v2.Field(i), visited) {
				return false
			}
		}
		return true
	case Map:
		if v1.IsNil() != v2.IsNil() {
			return false
		}
		if v1.Len() != v2.Len() {
			return false
		}
		if v1.Pointer() == v2.Pointer() {
			return true
		}
		for _, k := range v1.MapKeys() {
			val1 := v1.MapIndex(k)
			val2 := v2.MapIndex(k)
			if !val1.IsValid() || !val2.IsValid() || !deepValueEqual(val1, val2, visited) {
				return false
			}
		}
		return true
	case Func:
		return v1.IsNil() && v2.IsNil()
	default:
		// Normal equality suffices
		return v1.Interface() == v2.Interface() // try interface comparison as a fallback.
	}
}


================================================
FILE: go/ssa/interp/testdata/src/reflect/reflect.go
================================================
package reflect

type Type interface {
	String() string
	Kind() Kind
	Elem() Type
}

type Value struct {
}

func (Value) String() string

func (Value) Elem() Value
func (Value) Kind() Kind
func (Value) Int() int64
func (Value) IsValid() bool
func (Value) IsNil() bool
func (Value) Len() int
func (Value) Pointer() uintptr
func (Value) Index(i int) Value
func (Value) Type() Type
func (Value) Field(int) Value
func (Value) MapIndex(Value) Value
func (Value) MapKeys() []Value
func (Value) NumField() int
func (Value) Interface() interface{}

func SliceOf(Type) Type

func TypeOf(interface{}) Type

func ValueOf(interface{}) Value

type Kind uint

// Constants need to be kept in sync with the actual definitions for comparisons in tests.
const (
	Invalid Kind = iota
	Bool
	Int
	Int8
	Int16
	Int32
	Int64
	Uint
	Uint8
	Uint16
	Uint32
	Uint64
	Uintptr
	Float32
	Float64
	Complex64
	Complex128
	Array
	Chan
	Func
	Interface
	Map
	Pointer
	Slice
	String
	Struct
	UnsafePointer
)

const Ptr = Pointer


================================================
FILE: go/ssa/interp/testdata/src/runtime/runtime.go
================================================
package runtime

// An errorString represents a runtime error described by a single string.
type errorString string

func (e errorString) RuntimeError() {}

func (e errorString) Error() string {
	return "runtime error: " + string(e)
}

func Breakpoint()

type Error interface {
	error
	RuntimeError()
}

func GC()


================================================
FILE: go/ssa/interp/testdata/src/sort/sort.go
================================================
package sort

func Strings(x []string)
func Ints(x []int)
func Float64s(x []float64)


================================================
FILE: go/ssa/interp/testdata/src/strconv/strconv.go
================================================
package strconv

func Itoa(i int) string
func Atoi(s string) (int, error)

func FormatFloat(float64, byte, int, int) string


================================================
FILE: go/ssa/interp/testdata/src/strings/strings.go
================================================
package strings

func Replace(s, old, new string, n int) string

func Index(haystack, needle string) int

func Contains(haystack, needle string) bool {
	return Index(haystack, needle) >= 0
}

func HasPrefix(s, prefix string) bool {
	return len(s) >= len(prefix) && s[0:len(prefix)] == prefix
}

func EqualFold(s, t string) bool
func ToLower(s string) string

type Builder struct {
	s string
}

func (b *Builder) WriteString(s string) (int, error) {
	b.s += s
	return len(s), nil
}
func (b *Builder) String() string { return b.s }


================================================
FILE: go/ssa/interp/testdata/src/sync/sync.go
================================================
package sync

// Rudimentary implementation of a mutex for interp tests.
type Mutex struct {
	c chan int // Mutex is held when held c!=nil and is empty. Access is guarded by g.
}

func (m *Mutex) Lock() {
	c := ch(m)
	<-c
}

func (m *Mutex) Unlock() {
	c := ch(m)
	c <- 1
}

// sequentializes Mutex.c access.
var g = make(chan int, 1)

func init() {
	g <- 1
}

// ch initializes the m.c field if needed and returns it.
func ch(m *Mutex) chan int {
	<-g
	defer func() {
		g <- 1
	}()
	if m.c == nil {
		m.c = make(chan int, 1)
		m.c <- 1
	}
	return m.c
}


================================================
FILE: go/ssa/interp/testdata/src/time/time.go
================================================
package time

type Duration int64

func Sleep(Duration)


================================================
FILE: go/ssa/interp/testdata/src/unicode/utf8/utf8.go
================================================
package utf8

func DecodeRuneInString(string) (rune, int)

func DecodeRune(b []byte) (rune, int) {
	return DecodeRuneInString(string(b))
}

const RuneError = '\uFFFD'


================================================
FILE: go/ssa/interp/testdata/src/unsafe/unsafe.go
================================================
package unsafe


================================================
FILE: go/ssa/interp/testdata/static.go
================================================
package main

// Static tests of SSA builder (via the sanity checker).
// Dynamic semantics are not exercised.

func init() {
	// Regression test for issue 6806.
	ch := make(chan int)
	select {
	case n, _ := <-ch:
		_ = n
	default:
		// The default case disables the simplification of
		// select to a simple receive statement.
	}

	// value,ok-form receive where TypeOf(ok) is a named boolean.
	type mybool bool
	var x int
	var y mybool
	select {
	case x, y = <-ch:
	default:
		// The default case disables the simplification of
		// select to a simple receive statement.
	}
	_ = x
	_ = y
}

var a int

// Regression test for issue 7840 (covered by SSA sanity checker).
func bug7840() bool {
	// This creates a single-predecessor block with a φ-node.
	return false && a == 0 && a == 0
}

// A blocking select (sans "default:") cannot fall through.
// Regression test for issue 7022.
func bug7022() int {
	var c1, c2 chan int
	select {
	case <-c1:
		return 123
	case <-c2:
		return 456
	}
}

// Parens should not prevent intrinsic treatment of built-ins.
// (Regression test for a crash.)
func init() {
	_ = (new)(int)
	_ = (make)([]int, 0)
}

func main() {}


================================================
FILE: go/ssa/interp/testdata/typeassert.go
================================================
// Tests of type asserts.
// Requires type parameters.
package typeassert

type fooer interface{ foo() string }

type X int

func (_ X) foo() string { return "x" }

func f[T fooer](x T) func() string {
	return x.foo
}

func main() {
	if f[X](0)() != "x" {
		panic("f[X]() != 'x'")
	}

	p := false
	func() {
		defer func() {
			if recover() != nil {
				p = true
			}
		}()
		f[fooer](nil) // panics on x.foo when T is an interface and nil.
	}()
	if !p {
		panic("f[fooer] did not panic")
	}
}


================================================
FILE: go/ssa/interp/testdata/width32.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test interpretation on 32 bit widths.

package main

func main() {
	mapSize()
}

func mapSize() {
	// Tests for the size argument of make on a map type.
	const tooBigFor32 = 1<<33 - 1
	wantPanic(
		func() {
			_ = make(map[int]int, int64(tooBigFor32))
		},
		"runtime error: ssa.MakeMap.Reserve value 8589934591 does not fit in int",
	)

	// TODO: Enable the following if sizeof(int) can be different for host and target.
	// _ = make(map[int]int, tooBigFor32)
	//
	// Second arg to make in `make(map[int]int, tooBigFor32)` is an untyped int and
	// is converted into an int explicitly in ssa.
	// This has a different value on 32 and 64 bit systems.
}

func wantPanic(fn func(), s string) {
	defer func() {
		err := recover()
		if err == nil {
			panic("expected panic")
		}
		if got := err.(error).Error(); got != s {
			panic("expected panic " + s + " got " + got)
		}
	}()
	fn()
}


================================================
FILE: go/ssa/interp/testdata/zeros.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Test interpretation on zero values with type params.
package zeros

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

func tp0[T int | string | float64]() T { return T(0) }

func tpFalse[T ~bool]() T { return T(false) }

func tpEmptyString[T string | []byte]() T { return T("") }

func tpNil[T *int | []byte]() T { return T(nil) }

func main() {
	// zero values
	var zi int
	var zf float64
	var zs string

	assert(zi == int(0), "zero value of int is int(0)")
	assert(zf == float64(0), "zero value of float64 is float64(0)")
	assert(zs != string(0), "zero value of string is not string(0)")

	assert(zi == tp0[int](), "zero value of int is int(0)")
	assert(zf == tp0[float64](), "zero value of float64 is float64(0)")
	assert(zs != tp0[string](), "zero value of string is not string(0)")

	assert(zf == -0.0, "constant -0.0 is converted to 0.0")

	assert(!tpFalse[bool](), "zero value of bool is false")

	assert(tpEmptyString[string]() == zs, `zero value of string is string("")`)
	assert(len(tpEmptyString[[]byte]()) == 0, `[]byte("") is empty`)

	assert(tpNil[*int]() == nil, "nil is nil")
	assert(tpNil[[]byte]() == nil, "nil is nil")
}


================================================
FILE: go/ssa/interp/value.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package interp

// Values
//
// All interpreter values are "boxed" in the empty interface, value.
// The range of possible dynamic types within value are:
//
// - bool
// - numbers (all built-in int/float/complex types are distinguished)
// - string
// - map[value]value --- maps for which  usesBuiltinMap(keyType)
//   *hashmap        --- maps for which !usesBuiltinMap(keyType)
// - chan value
// - []value --- slices
// - iface --- interfaces.
// - structure --- structs.  Fields are ordered and accessed by numeric indices.
// - array --- arrays.
// - *value --- pointers.  Careful: *value is a distinct type from *array etc.
// - *ssa.Function \
//   *ssa.Builtin   } --- functions.  A nil 'func' is always of type *ssa.Function.
//   *closure      /
// - tuple --- as returned by Return, Next, "value,ok" modes, etc.
// - iter --- iterators from 'range' over map or string.
// - bad --- a poison pill for locals that have gone out of scope.
// - rtype -- the interpreter's concrete implementation of reflect.Type
// - **deferred -- the address of a frame's defer stack for a Defer._Stack.
//
// Note that nil is not on this list.
//
// Pay close attention to whether or not the dynamic type is a pointer.
// The compiler cannot help you since value is an empty interface.

import (
	"bytes"
	"fmt"
	"go/types"
	"io"
	"reflect"
	"strings"
	"unsafe"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/types/typeutil"
)

type value any

type tuple []value

type array []value

type iface struct {
	t types.Type // never an "untyped" type
	v value
}

type structure []value

// For map, array, *array, slice, string or channel.
type iter interface {
	// next returns a Tuple (key, value, ok).
	// key and value are unaliased, e.g. copies of the sequence element.
	next() tuple
}

type closure struct {
	Fn  *ssa.Function
	Env []value
}

type bad struct{}

type rtype struct {
	t types.Type
}

// Hash functions and equivalence relation:

// hashString computes the FNV hash of s.
func hashString(s string) int {
	var h uint32
	for i := 0; i < len(s); i++ {
		h ^= uint32(s[i])
		h *= 16777619
	}
	return int(h)
}

var hasher = typeutil.MakeHasher()

// hashType returns a hash for t such that
// types.Identical(x, y) => hashType(x) == hashType(y).
func hashType(t types.Type) int {
	return int(hasher.Hash(t))
}

// usesBuiltinMap returns true if the built-in hash function and
// equivalence relation for type t are consistent with those of the
// interpreter's representation of type t.  Such types are: all basic
// types (bool, numbers, string), pointers and channels.
//
// usesBuiltinMap returns false for types that require a custom map
// implementation: interfaces, arrays and structs.
//
// Panic ensues if t is an invalid map key type: function, map or slice.
func usesBuiltinMap(t types.Type) bool {
	switch t := t.(type) {
	case *types.Basic, *types.Chan, *types.Pointer:
		return true
	case *types.Named, *types.Alias:
		return usesBuiltinMap(t.Underlying())
	case *types.Interface, *types.Array, *types.Struct:
		return false
	}
	panic(fmt.Sprintf("invalid map key type: %T", t))
}

func (x array) eq(t types.Type, _y any) bool {
	y := _y.(array)
	tElt := t.Underlying().(*types.Array).Elem()
	for i, xi := range x {
		if !equals(tElt, xi, y[i]) {
			return false
		}
	}
	return true
}

func (x array) hash(t types.Type) int {
	h := 0
	tElt := t.Underlying().(*types.Array).Elem()
	for _, xi := range x {
		h += hash(t, tElt, xi)
	}
	return h
}

func (x structure) eq(t types.Type, _y any) bool {
	y := _y.(structure)
	tStruct := t.Underlying().(*types.Struct)
	for i, n := 0, tStruct.NumFields(); i < n; i++ {
		if f := tStruct.Field(i); !f.Anonymous() {
			if !equals(f.Type(), x[i], y[i]) {
				return false
			}
		}
	}
	return true
}

func (x structure) hash(t types.Type) int {
	tStruct := t.Underlying().(*types.Struct)
	h := 0
	for i, n := 0, tStruct.NumFields(); i < n; i++ {
		if f := tStruct.Field(i); !f.Anonymous() {
			h += hash(t, f.Type(), x[i])
		}
	}
	return h
}

// nil-tolerant variant of types.Identical.
func sameType(x, y types.Type) bool {
	if x == nil {
		return y == nil
	}
	return y != nil && types.Identical(x, y)
}

func (x iface) eq(t types.Type, _y any) bool {
	y := _y.(iface)
	return sameType(x.t, y.t) && (x.t == nil || equals(x.t, x.v, y.v))
}

func (x iface) hash(outer types.Type) int {
	return hashType(x.t)*8581 + hash(outer, x.t, x.v)
}

func (x rtype) hash(_ types.Type) int {
	return hashType(x.t)
}

func (x rtype) eq(_ types.Type, y any) bool {
	return types.Identical(x.t, y.(rtype).t)
}

// equals returns true iff x and y are equal according to Go's
// linguistic equivalence relation for type t.
// In a well-typed program, the dynamic types of x and y are
// guaranteed equal.
func equals(t types.Type, x, y value) bool {
	switch x := x.(type) {
	case bool:
		return x == y.(bool)
	case int:
		return x == y.(int)
	case int8:
		return x == y.(int8)
	case int16:
		return x == y.(int16)
	case int32:
		return x == y.(int32)
	case int64:
		return x == y.(int64)
	case uint:
		return x == y.(uint)
	case uint8:
		return x == y.(uint8)
	case uint16:
		return x == y.(uint16)
	case uint32:
		return x == y.(uint32)
	case uint64:
		return x == y.(uint64)
	case uintptr:
		return x == y.(uintptr)
	case float32:
		return x == y.(float32)
	case float64:
		return x == y.(float64)
	case complex64:
		return x == y.(complex64)
	case complex128:
		return x == y.(complex128)
	case string:
		return x == y.(string)
	case *value:
		return x == y.(*value)
	case chan value:
		return x == y.(chan value)
	case structure:
		return x.eq(t, y)
	case array:
		return x.eq(t, y)
	case iface:
		return x.eq(t, y)
	case rtype:
		return x.eq(t, y)
	}

	// Since map, func and slice don't support comparison, this
	// case is only reachable if one of x or y is literally nil
	// (handled in eqnil) or via interface{} values.
	panic(fmt.Sprintf("comparing uncomparable type %s", t))
}

// Returns an integer hash of x such that equals(x, y) => hash(x) == hash(y).
// The outer type is used only for the "unhashable" panic message.
func hash(outer, t types.Type, x value) int {
	switch x := x.(type) {
	case bool:
		if x {
			return 1
		}
		return 0
	case int:
		return x
	case int8:
		return int(x)
	case int16:
		return int(x)
	case int32:
		return int(x)
	case int64:
		return int(x)
	case uint:
		return int(x)
	case uint8:
		return int(x)
	case uint16:
		return int(x)
	case uint32:
		return int(x)
	case uint64:
		return int(x)
	case uintptr:
		return int(x)
	case float32:
		return int(x)
	case float64:
		return int(x)
	case complex64:
		return int(real(x))
	case complex128:
		return int(real(x))
	case string:
		return hashString(x)
	case *value:
		return int(uintptr(unsafe.Pointer(x)))
	case chan value:
		return int(uintptr(reflect.ValueOf(x).Pointer()))
	case structure:
		return x.hash(t)
	case array:
		return x.hash(t)
	case iface:
		return x.hash(t)
	case rtype:
		return x.hash(t)
	}
	panic(fmt.Sprintf("unhashable type %v", outer))
}

// reflect.Value struct values don't have a fixed shape, since the
// payload can be a scalar or an aggregate depending on the instance.
// So store (and load) can't simply use recursion over the shape of the
// rhs value, or the lhs, to copy the value; we need the static type
// information.  (We can't make reflect.Value a new basic data type
// because its "structness" is exposed to Go programs.)

// load returns the value of type T in *addr.
func load(T types.Type, addr *value) value {
	switch T := T.Underlying().(type) {
	case *types.Struct:
		v := (*addr).(structure)
		a := make(structure, len(v))
		for i := range a {
			a[i] = load(T.Field(i).Type(), &v[i])
		}
		return a
	case *types.Array:
		v := (*addr).(array)
		a := make(array, len(v))
		for i := range a {
			a[i] = load(T.Elem(), &v[i])
		}
		return a
	default:
		return *addr
	}
}

// store stores value v of type T into *addr.
func store(T types.Type, addr *value, v value) {
	switch T := T.Underlying().(type) {
	case *types.Struct:
		lhs := (*addr).(structure)
		rhs := v.(structure)
		for i := range lhs {
			store(T.Field(i).Type(), &lhs[i], rhs[i])
		}
	case *types.Array:
		lhs := (*addr).(array)
		rhs := v.(array)
		for i := range lhs {
			store(T.Elem(), &lhs[i], rhs[i])
		}
	default:
		*addr = v
	}
}

// Prints in the style of built-in println.
// (More or less; in gc println is actually a compiler intrinsic and
// can distinguish println(1) from println(interface{}(1)).)
func writeValue(buf *bytes.Buffer, v value) {
	switch v := v.(type) {
	case nil, bool, int, int8, int16, int32, int64, uint, uint8, uint16, uint32, uint64, uintptr, float32, float64, complex64, complex128, string:
		fmt.Fprintf(buf, "%v", v)

	case map[value]value:
		buf.WriteString("map[")
		sep := ""
		for k, e := range v {
			buf.WriteString(sep)
			sep = " "
			writeValue(buf, k)
			buf.WriteString(":")
			writeValue(buf, e)
		}
		buf.WriteString("]")

	case *hashmap:
		buf.WriteString("map[")
		sep := " "
		for _, e := range v.entries() {
			for e != nil {
				buf.WriteString(sep)
				sep = " "
				writeValue(buf, e.key)
				buf.WriteString(":")
				writeValue(buf, e.value)
				e = e.next
			}
		}
		buf.WriteString("]")

	case chan value:
		fmt.Fprintf(buf, "%v", v) // (an address)

	case *value:
		if v == nil {
			buf.WriteString("<nil>")
		} else {
			fmt.Fprintf(buf, "%p", v)
		}

	case iface:
		fmt.Fprintf(buf, "(%s, ", v.t)
		writeValue(buf, v.v)
		buf.WriteString(")")

	case structure:
		buf.WriteString("{")
		for i, e := range v {
			if i > 0 {
				buf.WriteString(" ")
			}
			writeValue(buf, e)
		}
		buf.WriteString("}")

	case array:
		buf.WriteString("[")
		for i, e := range v {
			if i > 0 {
				buf.WriteString(" ")
			}
			writeValue(buf, e)
		}
		buf.WriteString("]")

	case []value:
		buf.WriteString("[")
		for i, e := range v {
			if i > 0 {
				buf.WriteString(" ")
			}
			writeValue(buf, e)
		}
		buf.WriteString("]")

	case *ssa.Function, *ssa.Builtin, *closure:
		fmt.Fprintf(buf, "%p", v) // (an address)

	case rtype:
		buf.WriteString(v.t.String())

	case tuple:
		// Unreachable in well-formed Go programs
		buf.WriteString("(")
		for i, e := range v {
			if i > 0 {
				buf.WriteString(", ")
			}
			writeValue(buf, e)
		}
		buf.WriteString(")")

	default:
		fmt.Fprintf(buf, "<%T>", v)
	}
}

// Implements printing of Go values in the style of built-in println.
func toString(v value) string {
	var b bytes.Buffer
	writeValue(&b, v)
	return b.String()
}

// ------------------------------------------------------------------------
// Iterators

type stringIter struct {
	*strings.Reader
	i int
}

func (it *stringIter) next() tuple {
	okv := make(tuple, 3)
	ch, n, err := it.ReadRune()
	ok := err != io.EOF
	okv[0] = ok
	if ok {
		okv[1] = it.i
		okv[2] = ch
	}
	it.i += n
	return okv
}

type mapIter struct {
	iter *reflect.MapIter
	ok   bool
}

func (it *mapIter) next() tuple {
	it.ok = it.iter.Next()
	if !it.ok {
		return []value{false, nil, nil}
	}
	k, v := it.iter.Key().Interface(), it.iter.Value().Interface()
	return []value{true, k, v}
}

type hashmapIter struct {
	iter *reflect.MapIter
	ok   bool
	cur  *entry
}

func (it *hashmapIter) next() tuple {
	for {
		if it.cur != nil {
			k, v := it.cur.key, it.cur.value
			it.cur = it.cur.next
			return []value{true, k, v}
		}
		it.ok = it.iter.Next()
		if !it.ok {
			return []value{false, nil, nil}
		}
		it.cur = it.iter.Value().Interface().(*entry)
	}
}


================================================
FILE: go/ssa/lift.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines the lifting pass which tries to "lift" Alloc
// cells (new/local variables) into SSA registers, replacing loads
// with the dominating stored value, eliminating loads and stores, and
// inserting φ-nodes as needed.

// Cited papers and resources:
//
// Ron Cytron et al. 1991. Efficiently computing SSA form...
// http://doi.acm.org/10.1145/115372.115320
//
// Cooper, Harvey, Kennedy.  2001.  A Simple, Fast Dominance Algorithm.
// Software Practice and Experience 2001, 4:1-10.
// http://www.hipersoft.rice.edu/grads/publications/dom14.pdf
//
// Daniel Berlin, llvmdev mailing list, 2012.
// http://lists.cs.uiuc.edu/pipermail/llvmdev/2012-January/046638.html
// (Be sure to expand the whole thread.)

// TODO(adonovan): opt: there are many optimizations worth evaluating, and
// the conventional wisdom for SSA construction is that a simple
// algorithm well engineered often beats those of better asymptotic
// complexity on all but the most egregious inputs.
//
// Danny Berlin suggests that the Cooper et al. algorithm for
// computing the dominance frontier is superior to Cytron et al.
// Furthermore he recommends that rather than computing the DF for the
// whole function then renaming all alloc cells, it may be cheaper to
// compute the DF for each alloc cell separately and throw it away.
//
// Consider exploiting liveness information to avoid creating dead
// φ-nodes which we then immediately remove.
//
// Also see many other "TODO: opt" suggestions in the code.

import (
	"fmt"
	"go/token"
	"math/big"
	"os"
	"slices"

	"golang.org/x/tools/internal/typeparams"
)

// If true, show diagnostic information at each step of lifting.
// Very verbose.
const debugLifting = false

// domFrontier maps each block to the set of blocks in its dominance
// frontier.  The outer slice is conceptually a map keyed by
// Block.Index.  The inner slice is conceptually a set, possibly
// containing duplicates.
//
// TODO(adonovan): opt: measure impact of dups; consider a packed bit
// representation, e.g. big.Int, and bitwise parallel operations for
// the union step in the Children loop.
//
// domFrontier's methods mutate the slice's elements but not its
// length, so their receivers needn't be pointers.
type domFrontier [][]*BasicBlock

func (df domFrontier) add(u, v *BasicBlock) {
	p := &df[u.Index]
	*p = append(*p, v)
}

// build builds the dominance frontier df for the dominator (sub)tree
// rooted at u, using the Cytron et al. algorithm.
//
// TODO(adonovan): opt: consider Berlin approach, computing pruned SSA
// by pruning the entire IDF computation, rather than merely pruning
// the DF -> IDF step.
func (df domFrontier) build(u *BasicBlock) {
	// Encounter each node u in postorder of dom tree.
	for _, child := range u.dom.children {
		df.build(child)
	}
	for _, vb := range u.Succs {
		if v := vb.dom; v.idom != u {
			df.add(u, vb)
		}
	}
	for _, w := range u.dom.children {
		for _, vb := range df[w.Index] {
			// TODO(adonovan): opt: use word-parallel bitwise union.
			if v := vb.dom; v.idom != u {
				df.add(u, vb)
			}
		}
	}
}

func buildDomFrontier(fn *Function) domFrontier {
	df := make(domFrontier, len(fn.Blocks))
	df.build(fn.Blocks[0])
	if fn.Recover != nil {
		df.build(fn.Recover)
	}
	return df
}

func removeInstr(refs []Instruction, instr Instruction) []Instruction {
	return slices.DeleteFunc(refs, func(i Instruction) bool { return i == instr })
}

// lift replaces local and new Allocs accessed only with
// load/store by SSA registers, inserting φ-nodes where necessary.
// The result is a program in classical pruned SSA form.
//
// Preconditions:
// - fn has no dead blocks (blockopt has run).
// - Def/use info (Operands and Referrers) is up-to-date.
// - The dominator tree is up-to-date.
func lift(fn *Function) {
	// TODO(adonovan): opt: lots of little optimizations may be
	// worthwhile here, especially if they cause us to avoid
	// buildDomFrontier.  For example:
	//
	// - Alloc never loaded?  Eliminate.
	// - Alloc never stored?  Replace all loads with a zero constant.
	// - Alloc stored once?  Replace loads with dominating store;
	//   don't forget that an Alloc is itself an effective store
	//   of zero.
	// - Alloc used only within a single block?
	//   Use degenerate algorithm avoiding φ-nodes.
	// - Consider synergy with scalar replacement of aggregates (SRA).
	//   e.g. *(&x.f) where x is an Alloc.
	//   Perhaps we'd get better results if we generated this as x.f
	//   i.e. Field(x, .f) instead of Load(FieldIndex(x, .f)).
	//   Unclear.
	//
	// But we will start with the simplest correct code.
	df := buildDomFrontier(fn)

	if debugLifting {
		title := false
		for i, blocks := range df {
			if blocks != nil {
				if !title {
					fmt.Fprintf(os.Stderr, "Dominance frontier of %s:\n", fn)
					title = true
				}
				fmt.Fprintf(os.Stderr, "\t%s: %s\n", fn.Blocks[i], blocks)
			}
		}
	}

	newPhis := make(newPhiMap)

	// During this pass we will replace some BasicBlock.Instrs
	// (allocs, loads and stores) with nil, keeping a count in
	// BasicBlock.gaps.  At the end we will reset Instrs to the
	// concatenation of all non-dead newPhis and non-nil Instrs
	// for the block, reusing the original array if space permits.

	// While we're here, we also eliminate 'rundefers'
	// instructions and ssa:deferstack() in functions that contain no
	// 'defer' instructions. For now, we also eliminate
	// 's = ssa:deferstack()' calls if s doesn't escape, replacing s
	// with nil in Defer{DeferStack: s}. This has the same meaning,
	// but allows eliminating the intrinsic function `ssa:deferstack()`
	// (unless it is needed due to range-over-func instances). This gives
	// ssa users more time to support range-over-func.
	usesDefer := false
	deferstackAlloc, deferstackCall := deferstackPreamble(fn)
	eliminateDeferStack := deferstackAlloc != nil && !deferstackAlloc.Heap

	// A counter used to generate ~unique ids for Phi nodes, as an
	// aid to debugging.  We use large numbers to make them highly
	// visible.  All nodes are renumbered later.
	fresh := 1000

	// Determine which allocs we can lift and number them densely.
	// The renaming phase uses this numbering for compact maps.
	numAllocs := 0
	for _, b := range fn.Blocks {
		b.gaps = 0
		b.rundefers = 0
		for _, instr := range b.Instrs {
			switch instr := instr.(type) {
			case *Alloc:
				index := -1
				if liftAlloc(df, instr, newPhis, &fresh) {
					index = numAllocs
					numAllocs++
				}
				instr.index = index
			case *Defer:
				usesDefer = true
				if eliminateDeferStack {
					// Clear DeferStack and remove references to loads
					if instr.DeferStack != nil {
						if refs := instr.DeferStack.Referrers(); refs != nil {
							*refs = removeInstr(*refs, instr)
						}
						instr.DeferStack = nil
					}
				}
			case *RunDefers:
				b.rundefers++
			}
		}
	}

	// renaming maps an alloc (keyed by index) to its replacement
	// value.  Initially the renaming contains nil, signifying the
	// zero constant of the appropriate type; we construct the
	// Const lazily at most once on each path through the domtree.
	// TODO(adonovan): opt: cache per-function not per subtree.
	renaming := make([]Value, numAllocs)

	// Renaming.
	rename(fn.Blocks[0], renaming, newPhis)

	// Eliminate dead φ-nodes.
	removeDeadPhis(fn.Blocks, newPhis)

	// Eliminate ssa:deferstack() call.
	if eliminateDeferStack {
		b := deferstackCall.block
		for i, instr := range b.Instrs {
			if instr == deferstackCall {
				b.Instrs[i] = nil
				b.gaps++
				break
			}
		}
	}

	// Prepend remaining live φ-nodes to each block.
	for _, b := range fn.Blocks {
		nps := newPhis[b]
		j := len(nps)

		rundefersToKill := b.rundefers
		if usesDefer {
			rundefersToKill = 0
		}

		if j+b.gaps+rundefersToKill == 0 {
			continue // fast path: no new phis or gaps
		}

		// Compact nps + non-nil Instrs into a new slice.
		// TODO(adonovan): opt: compact in situ (rightwards)
		// if Instrs has sufficient space or slack.
		dst := make([]Instruction, len(b.Instrs)+j-b.gaps-rundefersToKill)
		for i, np := range nps {
			dst[i] = np.phi
		}
		for _, instr := range b.Instrs {
			if instr == nil {
				continue
			}
			if !usesDefer {
				if _, ok := instr.(*RunDefers); ok {
					continue
				}
			}
			dst[j] = instr
			j++
		}
		b.Instrs = dst
	}

	// Remove any fn.Locals that were lifted.
	j := 0
	for _, l := range fn.Locals {
		if l.index < 0 {
			fn.Locals[j] = l
			j++
		}
	}
	// Nil out fn.Locals[j:] to aid GC.
	for i := j; i < len(fn.Locals); i++ {
		fn.Locals[i] = nil
	}
	fn.Locals = fn.Locals[:j]
}

// removeDeadPhis removes φ-nodes not transitively needed by a
// non-Phi, non-DebugRef instruction.
func removeDeadPhis(blocks []*BasicBlock, newPhis newPhiMap) {
	// First pass: find the set of "live" φ-nodes: those reachable
	// from some non-Phi instruction.
	//
	// We compute reachability in reverse, starting from each φ,
	// rather than forwards, starting from each live non-Phi
	// instruction, because this way visits much less of the
	// Value graph.
	livePhis := make(map[*Phi]bool)
	for _, npList := range newPhis {
		for _, np := range npList {
			phi := np.phi
			if !livePhis[phi] && phiHasDirectReferrer(phi) {
				markLivePhi(livePhis, phi)
			}
		}
	}

	// Existing φ-nodes due to && and || operators
	// are all considered live (see Go issue 19622).
	for _, b := range blocks {
		for _, phi := range b.phis() {
			markLivePhi(livePhis, phi.(*Phi))
		}
	}

	// Second pass: eliminate unused phis from newPhis.
	for block, npList := range newPhis {
		j := 0
		for _, np := range npList {
			if livePhis[np.phi] {
				npList[j] = np
				j++
			} else {
				// discard it, first removing it from referrers
				for _, val := range np.phi.Edges {
					if refs := val.Referrers(); refs != nil {
						*refs = removeInstr(*refs, np.phi)
					}
				}
				np.phi.block = nil
			}
		}
		newPhis[block] = npList[:j]
	}
}

// markLivePhi marks phi, and all φ-nodes transitively reachable via
// its Operands, live.
func markLivePhi(livePhis map[*Phi]bool, phi *Phi) {
	livePhis[phi] = true
	for _, rand := range phi.Operands(nil) {
		if q, ok := (*rand).(*Phi); ok {
			if !livePhis[q] {
				markLivePhi(livePhis, q)
			}
		}
	}
}

// phiHasDirectReferrer reports whether phi is directly referred to by
// a non-Phi instruction.  Such instructions are the
// roots of the liveness traversal.
func phiHasDirectReferrer(phi *Phi) bool {
	for _, instr := range *phi.Referrers() {
		if _, ok := instr.(*Phi); !ok {
			return true
		}
	}
	return false
}

type blockSet struct{ big.Int } // (inherit methods from Int)

// add adds b to the set and returns true if the set changed.
func (s *blockSet) add(b *BasicBlock) bool {
	i := b.Index
	if s.Bit(i) != 0 {
		return false
	}
	s.SetBit(&s.Int, i, 1)
	return true
}

// take removes an arbitrary element from a set s and
// returns its index, or returns -1 if empty.
func (s *blockSet) take() int {
	l := s.BitLen()
	for i := range l {
		if s.Bit(i) == 1 {
			s.SetBit(&s.Int, i, 0)
			return i
		}
	}
	return -1
}

// newPhi is a pair of a newly introduced φ-node and the lifted Alloc
// it replaces.
type newPhi struct {
	phi   *Phi
	alloc *Alloc
}

// newPhiMap records for each basic block, the set of newPhis that
// must be prepended to the block.
type newPhiMap map[*BasicBlock][]newPhi

// liftAlloc determines whether alloc can be lifted into registers,
// and if so, it populates newPhis with all the φ-nodes it may require
// and returns true.
//
// fresh is a source of fresh ids for phi nodes.
func liftAlloc(df domFrontier, alloc *Alloc, newPhis newPhiMap, fresh *int) bool {
	// Don't lift result values in functions that defer
	// calls that may recover from panic.
	if fn := alloc.Parent(); fn.Recover != nil {
		if slices.Contains(fn.results, alloc) {
			return false
		}
	}

	// Compute defblocks, the set of blocks containing a
	// definition of the alloc cell.
	var defblocks blockSet
	for _, instr := range *alloc.Referrers() {
		// Bail out if we discover the alloc is not liftable;
		// the only operations permitted to use the alloc are
		// loads/stores into the cell, and DebugRef.
		switch instr := instr.(type) {
		case *Store:
			if instr.Val == alloc {
				return false // address used as value
			}
			if instr.Addr != alloc {
				panic("Alloc.Referrers is inconsistent")
			}
			defblocks.add(instr.Block())
		case *UnOp:
			if instr.Op != token.MUL {
				return false // not a load
			}
			if instr.X != alloc {
				panic("Alloc.Referrers is inconsistent")
			}
		case *DebugRef:
			// ok
		default:
			return false // some other instruction
		}
	}
	// The Alloc itself counts as a (zero) definition of the cell.
	defblocks.add(alloc.Block())

	if debugLifting {
		fmt.Fprintln(os.Stderr, "\tlifting ", alloc, alloc.Name())
	}

	fn := alloc.Parent()

	// Φ-insertion.
	//
	// What follows is the body of the main loop of the insert-φ
	// function described by Cytron et al, but instead of using
	// counter tricks, we just reset the 'hasAlready' and 'work'
	// sets each iteration.  These are bitmaps so it's pretty cheap.
	//
	// TODO(adonovan): opt: recycle slice storage for W,
	// hasAlready, defBlocks across liftAlloc calls.
	var hasAlready blockSet

	// Initialize W and work to defblocks.
	var work blockSet = defblocks // blocks seen
	var W blockSet                // blocks to do
	W.Set(&defblocks.Int)

	// Traverse iterated dominance frontier, inserting φ-nodes.
	for i := W.take(); i != -1; i = W.take() {
		u := fn.Blocks[i]
		for _, v := range df[u.Index] {
			if hasAlready.add(v) {
				// Create φ-node.
				// It will be prepended to v.Instrs later, if needed.
				phi := &Phi{
					Edges:   make([]Value, len(v.Preds)),
					Comment: alloc.Comment,
				}
				// This is merely a debugging aid:
				phi.setNum(*fresh)
				*fresh++

				phi.pos = alloc.Pos()
				phi.setType(typeparams.MustDeref(alloc.Type()))
				phi.block = v
				if debugLifting {
					fmt.Fprintf(os.Stderr, "\tplace %s = %s at block %s\n", phi.Name(), phi, v)
				}
				newPhis[v] = append(newPhis[v], newPhi{phi, alloc})

				if work.add(v) {
					W.add(v)
				}
			}
		}
	}

	return true
}

// replaceAll replaces all intraprocedural uses of x with y,
// updating x.Referrers and y.Referrers.
// Precondition: x.Referrers() != nil, i.e. x must be local to some function.
func replaceAll(x, y Value) {
	var rands []*Value
	pxrefs := x.Referrers()
	pyrefs := y.Referrers()
	for _, instr := range *pxrefs {
		rands = instr.Operands(rands[:0]) // recycle storage
		for _, rand := range rands {
			if *rand != nil {
				if *rand == x {
					*rand = y
				}
			}
		}
		if pyrefs != nil {
			*pyrefs = append(*pyrefs, instr) // dups ok
		}
	}
	*pxrefs = nil // x is now unreferenced
}

// renamed returns the value to which alloc is being renamed,
// constructing it lazily if it's the implicit zero initialization.
func renamed(renaming []Value, alloc *Alloc) Value {
	v := renaming[alloc.index]
	if v == nil {
		v = zeroConst(typeparams.MustDeref(alloc.Type()))
		renaming[alloc.index] = v
	}
	return v
}

// rename implements the (Cytron et al) SSA renaming algorithm, a
// preorder traversal of the dominator tree replacing all loads of
// Alloc cells with the value stored to that cell by the dominating
// store instruction.  For lifting, we need only consider loads,
// stores and φ-nodes.
//
// renaming is a map from *Alloc (keyed by index number) to its
// dominating stored value; newPhis[x] is the set of new φ-nodes to be
// prepended to block x.
func rename(u *BasicBlock, renaming []Value, newPhis newPhiMap) {
	// Each φ-node becomes the new name for its associated Alloc.
	for _, np := range newPhis[u] {
		phi := np.phi
		alloc := np.alloc
		renaming[alloc.index] = phi
	}

	// Rename loads and stores of allocs.
	for i, instr := range u.Instrs {
		switch instr := instr.(type) {
		case *Alloc:
			if instr.index >= 0 { // store of zero to Alloc cell
				// Replace dominated loads by the zero value.
				renaming[instr.index] = nil
				if debugLifting {
					fmt.Fprintf(os.Stderr, "\tkill alloc %s\n", instr)
				}
				// Delete the Alloc.
				u.Instrs[i] = nil
				u.gaps++
			}

		case *Store:
			if alloc, ok := instr.Addr.(*Alloc); ok && alloc.index >= 0 { // store to Alloc cell
				// Replace dominated loads by the stored value.
				renaming[alloc.index] = instr.Val
				if debugLifting {
					fmt.Fprintf(os.Stderr, "\tkill store %s; new value: %s\n",
						instr, instr.Val.Name())
				}
				// Remove the store from the referrer list of the stored value.
				if refs := instr.Val.Referrers(); refs != nil {
					*refs = removeInstr(*refs, instr)
				}
				// Delete the Store.
				u.Instrs[i] = nil
				u.gaps++
			}

		case *UnOp:
			if instr.Op == token.MUL {
				if alloc, ok := instr.X.(*Alloc); ok && alloc.index >= 0 { // load of Alloc cell
					newval := renamed(renaming, alloc)
					if debugLifting {
						fmt.Fprintf(os.Stderr, "\tupdate load %s = %s with %s\n",
							instr.Name(), instr, newval.Name())
					}
					// Replace all references to
					// the loaded value by the
					// dominating stored value.
					replaceAll(instr, newval)
					// Delete the Load.
					u.Instrs[i] = nil
					u.gaps++
				}
			}

		case *DebugRef:
			if alloc, ok := instr.X.(*Alloc); ok && alloc.index >= 0 { // ref of Alloc cell
				if instr.IsAddr {
					instr.X = renamed(renaming, alloc)
					instr.IsAddr = false

					// Add DebugRef to instr.X's referrers.
					if refs := instr.X.Referrers(); refs != nil {
						*refs = append(*refs, instr)
					}
				} else {
					// A source expression denotes the address
					// of an Alloc that was optimized away.
					instr.X = nil

					// Delete the DebugRef.
					u.Instrs[i] = nil
					u.gaps++
				}
			}
		}
	}

	// For each φ-node in a CFG successor, rename the edge.
	for _, v := range u.Succs {
		phis := newPhis[v]
		if len(phis) == 0 {
			continue
		}
		i := v.predIndex(u)
		for _, np := range phis {
			phi := np.phi
			alloc := np.alloc
			newval := renamed(renaming, alloc)
			if debugLifting {
				fmt.Fprintf(os.Stderr, "\tsetphi %s edge %s -> %s (#%d) (alloc=%s) := %s\n",
					phi.Name(), u, v, i, alloc.Name(), newval.Name())
			}
			phi.Edges[i] = newval
			if prefs := newval.Referrers(); prefs != nil {
				*prefs = append(*prefs, phi)
			}
		}
	}

	// Continue depth-first recursion over domtree, pushing a
	// fresh copy of the renaming map for each subtree.
	for i, v := range u.dom.children {
		r := renaming
		if i < len(u.dom.children)-1 {
			// On all but the final iteration, we must make
			// a copy to avoid destructive update.
			r = make([]Value, len(renaming))
			copy(r, renaming)
		}
		rename(v, r, newPhis)
	}

}

// deferstackPreamble returns the *Alloc and ssa:deferstack() call for fn.deferstack.
func deferstackPreamble(fn *Function) (*Alloc, *Call) {
	if alloc, _ := fn.vars[fn.deferstack].(*Alloc); alloc != nil {
		for _, ref := range *alloc.Referrers() {
			if ref, _ := ref.(*Store); ref != nil && ref.Addr == alloc {
				if call, _ := ref.Val.(*Call); call != nil {
					return alloc, call
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: go/ssa/lvalue.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// lvalues are the union of addressable expressions and map-index
// expressions.

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/internal/typeparams"
)

// An lvalue represents an assignable location that may appear on the
// left-hand side of an assignment.  This is a generalization of a
// pointer to permit updates to elements of maps.
type lvalue interface {
	store(fn *Function, v Value) // stores v into the location
	load(fn *Function) Value     // loads the contents of the location
	address(fn *Function) Value  // address of the location
	typ() types.Type             // returns the type of the location
}

// An address is an lvalue represented by a true pointer.
type address struct {
	addr Value     // must have a pointer core type.
	pos  token.Pos // source position
	expr ast.Expr  // source syntax of the value (not address) [debug mode]
}

func (a *address) load(fn *Function) Value {
	load := emitLoad(fn, a.addr)
	load.pos = a.pos
	return load
}

func (a *address) store(fn *Function, v Value) {
	store := emitStore(fn, a.addr, v, a.pos)
	if a.expr != nil {
		// store.Val is v, converted for assignability.
		emitDebugRef(fn, a.expr, store.Val, false)
	}
}

func (a *address) address(fn *Function) Value {
	if a.expr != nil {
		emitDebugRef(fn, a.expr, a.addr, true)
	}
	return a.addr
}

func (a *address) typ() types.Type {
	return typeparams.MustDeref(a.addr.Type())
}

// An element is an lvalue represented by m[k], the location of an
// element of a map.  These locations are not addressable
// since pointers cannot be formed from them, but they do support
// load() and store().
type element struct {
	m, k Value      // map
	t    types.Type // map element type
	pos  token.Pos  // source position of colon ({k:v}) or lbrack (m[k]=v)
}

func (e *element) load(fn *Function) Value {
	l := &Lookup{
		X:     e.m,
		Index: e.k,
	}
	l.setPos(e.pos)
	l.setType(e.t)
	return fn.emit(l)
}

func (e *element) store(fn *Function, v Value) {
	up := &MapUpdate{
		Map:   e.m,
		Key:   e.k,
		Value: emitConv(fn, v, e.t),
	}
	up.pos = e.pos
	fn.emit(up)
}

func (e *element) address(fn *Function) Value {
	panic("map elements are not addressable")
}

func (e *element) typ() types.Type {
	return e.t
}

// A lazyAddress is an lvalue whose address is the result of an instruction.
// These work like an *address except a new address.address() Value
// is created on each load, store and address call.
// A lazyAddress can be used to control when a side effect (nil pointer
// dereference, index out of bounds) of using a location happens.
type lazyAddress struct {
	addr func(fn *Function) Value // emit to fn the computation of the address
	t    types.Type               // type of the location
	pos  token.Pos                // source position
	expr ast.Expr                 // source syntax of the value (not address) [debug mode]
}

func (l *lazyAddress) load(fn *Function) Value {
	load := emitLoad(fn, l.addr(fn))
	load.pos = l.pos
	return load
}

func (l *lazyAddress) store(fn *Function, v Value) {
	store := emitStore(fn, l.addr(fn), v, l.pos)
	if l.expr != nil {
		// store.Val is v, converted for assignability.
		emitDebugRef(fn, l.expr, store.Val, false)
	}
}

func (l *lazyAddress) address(fn *Function) Value {
	addr := l.addr(fn)
	if l.expr != nil {
		emitDebugRef(fn, l.expr, addr, true)
	}
	return addr
}

func (l *lazyAddress) typ() types.Type { return l.t }

// A blank is a dummy variable whose name is "_".
// It is not reified: loads are illegal and stores are ignored.
type blank struct{}

func (bl blank) load(fn *Function) Value {
	panic("blank.load is illegal")
}

func (bl blank) store(fn *Function, v Value) {
	// no-op
}

func (bl blank) address(fn *Function) Value {
	panic("blank var is not addressable")
}

func (bl blank) typ() types.Type {
	// This should be the type of the blank Ident; the typechecker
	// doesn't provide this yet, but fortunately, we don't need it
	// yet either.
	panic("blank.typ is unimplemented")
}


================================================
FILE: go/ssa/methods.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines utilities for population of method sets.

import (
	"fmt"
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

// MethodValue returns the Function implementing method sel, building
// wrapper methods on demand. It returns nil if sel denotes an
// interface or generic method.
//
// Precondition: sel.Kind() == MethodVal.
//
// Thread-safe.
//
// Acquires prog.methodsMu.
func (prog *Program) MethodValue(sel *types.Selection) *Function {
	if sel.Kind() != types.MethodVal {
		panic(fmt.Sprintf("MethodValue(%s) kind != MethodVal", sel))
	}
	T := sel.Recv()
	if types.IsInterface(T) {
		return nil // interface method or type parameter
	}

	if prog.isParameterized(T) {
		return nil // generic method
	}

	if prog.mode&LogSource != 0 {
		defer logStack("MethodValue %s %v", T, sel)()
	}

	var b builder

	m := func() *Function {
		prog.methodsMu.Lock()
		defer prog.methodsMu.Unlock()

		// Get or create SSA method set.
		mset, ok := prog.methodSets.At(T).(*methodSet)
		if !ok {
			mset = &methodSet{mapping: make(map[string]*Function)}
			prog.methodSets.Set(T, mset)
		}

		// Get or create SSA method.
		id := sel.Obj().Id()
		fn, ok := mset.mapping[id]
		if !ok {
			obj := sel.Obj().(*types.Func)
			needsPromotion := len(sel.Index()) > 1
			needsIndirection := !isPointer(recvType(obj)) && isPointer(T)
			if needsPromotion || needsIndirection {
				fn = createWrapper(prog, toSelection(sel))
				fn.buildshared = b.shared()
				b.enqueue(fn)
			} else {
				fn = prog.objectMethod(obj, &b)
			}
			if fn.Signature.Recv() == nil {
				panic(fn)
			}
			mset.mapping[id] = fn
		} else {
			b.waitForSharedFunction(fn)
		}

		return fn
	}()

	b.iterate()

	return m
}

// objectMethod returns the Function for a given method symbol.
// The symbol may be an instance of a generic function. It need not
// belong to an existing SSA package created by a call to
// prog.CreatePackage.
//
// objectMethod panics if the function is not a method.
//
// Acquires prog.objectMethodsMu.
func (prog *Program) objectMethod(obj *types.Func, b *builder) *Function {
	sig := obj.Type().(*types.Signature)
	if sig.Recv() == nil {
		panic("not a method: " + obj.String())
	}

	// Belongs to a created package?
	if fn := prog.FuncValue(obj); fn != nil {
		return fn
	}

	// Instantiation of generic?
	if originObj := obj.Origin(); originObj != obj {
		origin := prog.objectMethod(originObj, b)
		assert(origin.typeparams.Len() > 0, "origin is not generic")
		targs := receiverTypeArgs(obj)
		return origin.instance(targs, b)
	}

	// Consult/update cache of methods created from types.Func.
	prog.objectMethodsMu.Lock()
	defer prog.objectMethodsMu.Unlock()
	fn, ok := prog.objectMethods[obj]
	if !ok {
		fn = createFunction(prog, obj, obj.Name(), nil, nil, "")
		fn.Synthetic = "from type information (on demand)"
		fn.buildshared = b.shared()
		b.enqueue(fn)

		if prog.objectMethods == nil {
			prog.objectMethods = make(map[*types.Func]*Function)
		}
		prog.objectMethods[obj] = fn
	} else {
		b.waitForSharedFunction(fn)
	}
	return fn
}

// LookupMethod returns the implementation of the method of type T
// identified by (pkg, name).  It returns nil if the method exists but
// is an interface method or generic method, and panics if T has no such method.
func (prog *Program) LookupMethod(T types.Type, pkg *types.Package, name string) *Function {
	sel := prog.MethodSets.MethodSet(T).Lookup(pkg, name)
	if sel == nil {
		panic(fmt.Sprintf("%s has no method %s", T, types.Id(pkg, name)))
	}
	return prog.MethodValue(sel)
}

// methodSet contains the (concrete) methods of a concrete type (non-interface, non-parameterized).
type methodSet struct {
	mapping map[string]*Function // populated lazily
}

// RuntimeTypes returns a new unordered slice containing all types in
// the program for which a runtime type is required.
//
// A runtime type is required for any non-parameterized, non-interface
// type that is converted to an interface, or for any type (including
// interface types) derivable from one through reflection.
//
// The methods of such types may be reachable through reflection or
// interface calls even if they are never called directly.
//
// Thread-safe.
//
// Acquires prog.makeInterfaceTypesMu.
func (prog *Program) RuntimeTypes() []types.Type {
	prog.makeInterfaceTypesMu.Lock()
	defer prog.makeInterfaceTypesMu.Unlock()

	// Compute the derived types on demand, since many SSA clients
	// never call RuntimeTypes, and those that do typically call
	// it once (often within ssautil.AllFunctions, which will
	// eventually not use it; see Go issue #69291.) This
	// eliminates the need to eagerly compute all the element
	// types during SSA building.
	var runtimeTypes []types.Type
	add := func(t types.Type) { runtimeTypes = append(runtimeTypes, t) }
	var set typeutil.Map // for de-duping identical types
	for t := range prog.makeInterfaceTypes {
		typesinternal.ForEachElement(&set, &prog.MethodSets, t, add)
	}

	return runtimeTypes
}


================================================
FILE: go/ssa/methods_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
)

// Tests that MethodValue returns the expected method.
func TestMethodValue(t *testing.T) {
	input := `
package p

type I interface{ M() }

type S int
func (S) M() {}
type R[T any] struct{ S }

var i I
var s S
var r R[string]

func selections[T any]() {
	_ = i.M
	_ = s.M
	_ = r.M

	var v R[T]
	_ = v.M
}
`

	// Parse the file.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "input.go", input, 0)
	if err != nil {
		t.Error(err)
		return
	}

	// Build an SSA program from the parsed file.
	p, info, err := ssautil.BuildPackage(&types.Config{}, fset,
		types.NewPackage("p", ""), []*ast.File{f}, ssa.SanityCheckFunctions)
	if err != nil {
		t.Error(err)
		return
	}

	// Collect all of the *types.Selection in the function "selections".
	var selections []*types.Selection
	for _, decl := range f.Decls {
		if fn, ok := decl.(*ast.FuncDecl); ok && fn.Name.Name == "selections" {
			for _, stmt := range fn.Body.List {
				if assign, ok := stmt.(*ast.AssignStmt); ok {
					sel := assign.Rhs[0].(*ast.SelectorExpr)
					selections = append(selections, info.Selections[sel])
				}
			}
		}
	}

	wants := map[string]string{
		"method (p.S) M()":         "(p.S).M",
		"method (p.R[string]) M()": "(p.R[string]).M",
		"method (p.I) M()":         "nil", // interface
		"method (p.R[T]) M()":      "nil", // parameterized
	}
	if len(wants) != len(selections) {
		t.Fatalf("Wanted %d selections. got %d", len(wants), len(selections))
	}
	for _, selection := range selections {
		var got string
		if m := p.Prog.MethodValue(selection); m != nil {
			got = m.String()
		} else {
			got = "nil"
		}
		if want := wants[selection.String()]; want != got {
			t.Errorf("p.Prog.MethodValue(%s) expected %q. got %q", selection, want, got)
		}
	}
}


================================================
FILE: go/ssa/mode.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines the BuilderMode type and its command-line flag.

import (
	"bytes"
	"fmt"
)

// BuilderMode is a bitmask of options for diagnostics and checking.
//
// *BuilderMode satisfies the flag.Value interface.  Example:
//
//	var mode = ssa.BuilderMode(0)
//	func init() { flag.Var(&mode, "build", ssa.BuilderModeDoc) }
type BuilderMode uint

const (
	PrintPackages        BuilderMode = 1 << iota // Print package inventory to stdout
	PrintFunctions                               // Print function SSA code to stdout
	LogSource                                    // Log source locations as SSA builder progresses
	SanityCheckFunctions                         // Perform sanity checking of function bodies
	NaiveForm                                    // Build naïve SSA form: don't replace local loads/stores with registers
	BuildSerially                                // Build packages serially, not in parallel.
	GlobalDebug                                  // Enable debug info for all packages
	BareInits                                    // Build init functions without guards or calls to dependent inits
	InstantiateGenerics                          // Instantiate generics functions (monomorphize) while building
)

const BuilderModeDoc = `Options controlling the SSA builder.
The value is a sequence of zero or more of these letters:
C	perform sanity [C]hecking of the SSA form.
D	include [D]ebug info for every function.
P	print [P]ackage inventory.
F	print [F]unction SSA code.
S	log [S]ource locations as SSA builder progresses.
L	build distinct packages seria[L]ly instead of in parallel.
N	build [N]aive SSA form: don't replace local loads/stores with registers.
I	build bare [I]nit functions: no init guards or calls to dependent inits.
G   instantiate [G]eneric function bodies via monomorphization
`

func (m BuilderMode) String() string {
	var buf bytes.Buffer
	if m&GlobalDebug != 0 {
		buf.WriteByte('D')
	}
	if m&PrintPackages != 0 {
		buf.WriteByte('P')
	}
	if m&PrintFunctions != 0 {
		buf.WriteByte('F')
	}
	if m&LogSource != 0 {
		buf.WriteByte('S')
	}
	if m&SanityCheckFunctions != 0 {
		buf.WriteByte('C')
	}
	if m&NaiveForm != 0 {
		buf.WriteByte('N')
	}
	if m&BuildSerially != 0 {
		buf.WriteByte('L')
	}
	if m&BareInits != 0 {
		buf.WriteByte('I')
	}
	if m&InstantiateGenerics != 0 {
		buf.WriteByte('G')
	}
	return buf.String()
}

// Set parses the flag characters in s and updates *m.
func (m *BuilderMode) Set(s string) error {
	var mode BuilderMode
	for _, c := range s {
		switch c {
		case 'D':
			mode |= GlobalDebug
		case 'P':
			mode |= PrintPackages
		case 'F':
			mode |= PrintFunctions
		case 'S':
			mode |= LogSource | BuildSerially
		case 'C':
			mode |= SanityCheckFunctions
		case 'N':
			mode |= NaiveForm
		case 'L':
			mode |= BuildSerially
		case 'I':
			mode |= BareInits
		case 'G':
			mode |= InstantiateGenerics
		default:
			return fmt.Errorf("unknown BuilderMode option: %q", c)
		}
	}
	*m = mode
	return nil
}

// Get returns m.
func (m BuilderMode) Get() any { return m }


================================================
FILE: go/ssa/print.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file implements the String() methods for all Value and
// Instruction types.

import (
	"bytes"
	"fmt"
	"go/types"
	"io"
	"reflect"
	"sort"
	"strings"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
)

// relName returns the name of v relative to i.
// In most cases, this is identical to v.Name(), but references to
// Functions (including methods) and Globals use RelString and
// all types are displayed with relType, so that only cross-package
// references are package-qualified.
func relName(v Value, i Instruction) string {
	var from *types.Package
	if i != nil {
		from = i.Parent().relPkg()
	}
	switch v := v.(type) {
	case Member: // *Function or *Global
		return v.RelString(from)
	case *Const:
		return v.RelString(from)
	}
	return v.Name()
}

func relType(t types.Type, from *types.Package) string {
	return types.TypeString(t, types.RelativeTo(from))
}

func relTerm(term *types.Term, from *types.Package) string {
	s := relType(term.Type(), from)
	if term.Tilde() {
		return "~" + s
	}
	return s
}

func relString(m Member, from *types.Package) string {
	// NB: not all globals have an Object (e.g. init$guard),
	// so use Package().Object not Object.Package().
	if pkg := m.Package().Pkg; pkg != nil && pkg != from {
		return fmt.Sprintf("%s.%s", pkg.Path(), m.Name())
	}
	return m.Name()
}

// Value.String()
//
// This method is provided only for debugging.
// It never appears in disassembly, which uses Value.Name().

func (v *Parameter) String() string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("parameter %s : %s", v.Name(), relType(v.Type(), from))
}

func (v *FreeVar) String() string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("freevar %s : %s", v.Name(), relType(v.Type(), from))
}

func (v *Builtin) String() string {
	return fmt.Sprintf("builtin %s", v.Name())
}

// Instruction.String()

func (v *Alloc) String() string {
	op := "local"
	if v.Heap {
		op = "new"
	}
	from := v.Parent().relPkg()
	return fmt.Sprintf("%s %s (%s)", op, relType(typeparams.MustDeref(v.Type()), from), v.Comment)
}

func (v *Phi) String() string {
	var b bytes.Buffer
	b.WriteString("phi [")
	for i, edge := range v.Edges {
		if i > 0 {
			b.WriteString(", ")
		}
		// Be robust against malformed CFG.
		if v.block == nil {
			b.WriteString("??")
			continue
		}
		block := -1
		if i < len(v.block.Preds) {
			block = v.block.Preds[i].Index
		}
		fmt.Fprintf(&b, "%d: ", block)
		edgeVal := "<nil>" // be robust
		if edge != nil {
			edgeVal = relName(edge, v)
		}
		b.WriteString(edgeVal)
	}
	b.WriteString("]")
	if v.Comment != "" {
		b.WriteString(" #")
		b.WriteString(v.Comment)
	}
	return b.String()
}

func printCall(v *CallCommon, prefix string, instr Instruction) string {
	var b bytes.Buffer
	b.WriteString(prefix)
	if !v.IsInvoke() {
		b.WriteString(relName(v.Value, instr))
	} else {
		fmt.Fprintf(&b, "invoke %s.%s", relName(v.Value, instr), v.Method.Name())
	}
	b.WriteString("(")
	for i, arg := range v.Args {
		if i > 0 {
			b.WriteString(", ")
		}
		b.WriteString(relName(arg, instr))
	}
	if v.Signature().Variadic() {
		b.WriteString("...")
	}
	b.WriteString(")")
	return b.String()
}

func (c *CallCommon) String() string {
	return printCall(c, "", nil)
}

func (v *Call) String() string {
	return printCall(&v.Call, "", v)
}

func (v *BinOp) String() string {
	return fmt.Sprintf("%s %s %s", relName(v.X, v), v.Op.String(), relName(v.Y, v))
}

func (v *UnOp) String() string {
	return fmt.Sprintf("%s%s%s", v.Op, relName(v.X, v), commaOk(v.CommaOk))
}

func printConv(prefix string, v, x Value) string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("%s %s <- %s (%s)",
		prefix,
		relType(v.Type(), from),
		relType(x.Type(), from),
		relName(x, v.(Instruction)))
}

func (v *ChangeType) String() string          { return printConv("changetype", v, v.X) }
func (v *Convert) String() string             { return printConv("convert", v, v.X) }
func (v *ChangeInterface) String() string     { return printConv("change interface", v, v.X) }
func (v *SliceToArrayPointer) String() string { return printConv("slice to array pointer", v, v.X) }
func (v *MakeInterface) String() string       { return printConv("make", v, v.X) }

func (v *MultiConvert) String() string {
	from := v.Parent().relPkg()

	var b strings.Builder
	b.WriteString(printConv("multiconvert", v, v.X))
	b.WriteString(" [")
	for i, s := range termListOf(v.from) {
		for j, d := range termListOf(v.to) {
			if i != 0 || j != 0 {
				b.WriteString(" | ")
			}
			fmt.Fprintf(&b, "%s <- %s", relTerm(d, from), relTerm(s, from))
		}
	}
	b.WriteString("]")
	return b.String()
}

func (v *MakeClosure) String() string {
	var b bytes.Buffer
	fmt.Fprintf(&b, "make closure %s", relName(v.Fn, v))
	if v.Bindings != nil {
		b.WriteString(" [")
		for i, c := range v.Bindings {
			if i > 0 {
				b.WriteString(", ")
			}
			b.WriteString(relName(c, v))
		}
		b.WriteString("]")
	}
	return b.String()
}

func (v *MakeSlice) String() string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("make %s %s %s",
		relType(v.Type(), from),
		relName(v.Len, v),
		relName(v.Cap, v))
}

func (v *Slice) String() string {
	var b bytes.Buffer
	b.WriteString("slice ")
	b.WriteString(relName(v.X, v))
	b.WriteString("[")
	if v.Low != nil {
		b.WriteString(relName(v.Low, v))
	}
	b.WriteString(":")
	if v.High != nil {
		b.WriteString(relName(v.High, v))
	}
	if v.Max != nil {
		b.WriteString(":")
		b.WriteString(relName(v.Max, v))
	}
	b.WriteString("]")
	return b.String()
}

func (v *MakeMap) String() string {
	res := ""
	if v.Reserve != nil {
		res = relName(v.Reserve, v)
	}
	from := v.Parent().relPkg()
	return fmt.Sprintf("make %s %s", relType(v.Type(), from), res)
}

func (v *MakeChan) String() string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("make %s %s", relType(v.Type(), from), relName(v.Size, v))
}

func (v *FieldAddr) String() string {
	// Be robust against a bad index.
	name := "?"
	if fld := fieldOf(typeparams.MustDeref(v.X.Type()), v.Field); fld != nil {
		name = fld.Name()
	}
	return fmt.Sprintf("&%s.%s [#%d]", relName(v.X, v), name, v.Field)
}

func (v *Field) String() string {
	// Be robust against a bad index.
	name := "?"
	if fld := fieldOf(v.X.Type(), v.Field); fld != nil {
		name = fld.Name()
	}
	return fmt.Sprintf("%s.%s [#%d]", relName(v.X, v), name, v.Field)
}

func (v *IndexAddr) String() string {
	return fmt.Sprintf("&%s[%s]", relName(v.X, v), relName(v.Index, v))
}

func (v *Index) String() string {
	return fmt.Sprintf("%s[%s]", relName(v.X, v), relName(v.Index, v))
}

func (v *Lookup) String() string {
	return fmt.Sprintf("%s[%s]%s", relName(v.X, v), relName(v.Index, v), commaOk(v.CommaOk))
}

func (v *Range) String() string {
	return "range " + relName(v.X, v)
}

func (v *Next) String() string {
	return "next " + relName(v.Iter, v)
}

func (v *TypeAssert) String() string {
	from := v.Parent().relPkg()
	return fmt.Sprintf("typeassert%s %s.(%s)", commaOk(v.CommaOk), relName(v.X, v), relType(v.AssertedType, from))
}

func (v *Extract) String() string {
	return fmt.Sprintf("extract %s #%d", relName(v.Tuple, v), v.Index)
}

func (s *Jump) String() string {
	// Be robust against malformed CFG.
	block := -1
	if s.block != nil && len(s.block.Succs) == 1 {
		block = s.block.Succs[0].Index
	}
	return fmt.Sprintf("jump %d", block)
}

func (s *If) String() string {
	// Be robust against malformed CFG.
	tblock, fblock := -1, -1
	if s.block != nil && len(s.block.Succs) == 2 {
		tblock = s.block.Succs[0].Index
		fblock = s.block.Succs[1].Index
	}
	return fmt.Sprintf("if %s goto %d else %d", relName(s.Cond, s), tblock, fblock)
}

func (s *Go) String() string {
	return printCall(&s.Call, "go ", s)
}

func (s *Panic) String() string {
	return "panic " + relName(s.X, s)
}

func (s *Return) String() string {
	var b bytes.Buffer
	b.WriteString("return")
	for i, r := range s.Results {
		if i == 0 {
			b.WriteString(" ")
		} else {
			b.WriteString(", ")
		}
		b.WriteString(relName(r, s))
	}
	return b.String()
}

func (*RunDefers) String() string {
	return "rundefers"
}

func (s *Send) String() string {
	return fmt.Sprintf("send %s <- %s", relName(s.Chan, s), relName(s.X, s))
}

func (s *Defer) String() string {
	prefix := "defer "
	if s.DeferStack != nil {
		prefix += "[" + relName(s.DeferStack, s) + "] "
	}
	c := printCall(&s.Call, prefix, s)
	return c
}

func (s *Select) String() string {
	var b bytes.Buffer
	for i, st := range s.States {
		if i > 0 {
			b.WriteString(", ")
		}
		if st.Dir == types.RecvOnly {
			b.WriteString("<-")
			b.WriteString(relName(st.Chan, s))
		} else {
			b.WriteString(relName(st.Chan, s))
			b.WriteString("<-")
			b.WriteString(relName(st.Send, s))
		}
	}
	non := ""
	if !s.Blocking {
		non = "non"
	}
	return fmt.Sprintf("select %sblocking [%s]", non, b.String())
}

func (s *Store) String() string {
	return fmt.Sprintf("*%s = %s", relName(s.Addr, s), relName(s.Val, s))
}

func (s *MapUpdate) String() string {
	return fmt.Sprintf("%s[%s] = %s", relName(s.Map, s), relName(s.Key, s), relName(s.Value, s))
}

func (s *DebugRef) String() string {
	p := s.Parent().Prog.Fset.Position(s.Pos())
	var descr any
	if s.object != nil {
		descr = s.object // e.g. "var x int"
	} else {
		descr = reflect.TypeOf(s.Expr) // e.g. "*ast.CallExpr"
	}
	var addr string
	if s.IsAddr {
		addr = "address of "
	}
	return fmt.Sprintf("; %s%s @ %d:%d is %s", addr, descr, p.Line, p.Column, s.X.Name())
}

func (p *Package) String() string {
	return "package " + p.Pkg.Path()
}

var _ io.WriterTo = (*Package)(nil) // *Package implements io.Writer

func (p *Package) WriteTo(w io.Writer) (int64, error) {
	var buf bytes.Buffer
	WritePackage(&buf, p)
	n, err := w.Write(buf.Bytes())
	return int64(n), err
}

// WritePackage writes to buf a human-readable summary of p.
func WritePackage(buf *bytes.Buffer, p *Package) {
	fmt.Fprintf(buf, "%s:\n", p)

	var names []string
	maxname := 0
	for name := range p.Members {
		if l := len(name); l > maxname {
			maxname = l
		}
		names = append(names, name)
	}

	from := p.Pkg
	sort.Strings(names)
	for _, name := range names {
		switch mem := p.Members[name].(type) {
		case *NamedConst:
			fmt.Fprintf(buf, "  const %-*s %s = %s\n",
				maxname, name, mem.Name(), mem.Value.RelString(from))

		case *Function:
			fmt.Fprintf(buf, "  func  %-*s %s\n",
				maxname, name, relType(mem.Type(), from))

		case *Type:
			fmt.Fprintf(buf, "  type  %-*s %s\n",
				maxname, name, relType(mem.Type().Underlying(), from))
			for _, meth := range typeutil.IntuitiveMethodSet(mem.Type(), &p.Prog.MethodSets) {
				fmt.Fprintf(buf, "    %s\n", types.SelectionString(meth, types.RelativeTo(from)))
			}

		case *Global:
			fmt.Fprintf(buf, "  var   %-*s %s\n",
				maxname, name, relType(typeparams.MustDeref(mem.Type()), from))
		}
	}

	fmt.Fprintf(buf, "\n")
}

func commaOk(x bool) string {
	if x {
		return ",ok"
	}
	return ""
}


================================================
FILE: go/ssa/sanity.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// An optional pass for sanity-checking invariants of the SSA representation.
// Currently it checks CFG invariants but little at the instruction level.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/types"
	"io"
	"os"
	"slices"
	"strings"
)

type sanity struct {
	reporter io.Writer
	fn       *Function
	block    *BasicBlock
	instrs   map[Instruction]unit
	insane   bool
}

// sanityCheck performs integrity checking of the SSA representation
// of the function fn (which must have been "built") and returns true
// if it was valid. Diagnostics are written to reporter if non-nil,
// os.Stderr otherwise. Some diagnostics are only warnings and do not
// imply a negative result.
//
// Sanity-checking is intended to facilitate the debugging of code
// transformation passes.
func sanityCheck(fn *Function, reporter io.Writer) bool {
	if reporter == nil {
		reporter = os.Stderr
	}
	return (&sanity{reporter: reporter}).checkFunction(fn)
}

// mustSanityCheck is like sanityCheck but panics instead of returning
// a negative result.
func mustSanityCheck(fn *Function, reporter io.Writer) {
	if !sanityCheck(fn, reporter) {
		fn.WriteTo(os.Stderr)
		panic("SanityCheck failed")
	}
}

func (s *sanity) diagnostic(prefix, format string, args ...any) {
	fmt.Fprintf(s.reporter, "%s: function %s", prefix, s.fn)
	if s.block != nil {
		fmt.Fprintf(s.reporter, ", block %s", s.block)
	}
	io.WriteString(s.reporter, ": ")
	fmt.Fprintf(s.reporter, format, args...)
	io.WriteString(s.reporter, "\n")
}

func (s *sanity) errorf(format string, args ...any) {
	s.insane = true
	s.diagnostic("Error", format, args...)
}

func (s *sanity) warnf(format string, args ...any) {
	s.diagnostic("Warning", format, args...)
}

// findDuplicate returns an arbitrary basic block that appeared more
// than once in blocks, or nil if all were unique.
func findDuplicate(blocks []*BasicBlock) *BasicBlock {
	if len(blocks) < 2 {
		return nil
	}
	if blocks[0] == blocks[1] {
		return blocks[0]
	}
	// Slow path:
	m := make(map[*BasicBlock]bool)
	for _, b := range blocks {
		if m[b] {
			return b
		}
		m[b] = true
	}
	return nil
}

func (s *sanity) checkInstr(idx int, instr Instruction) {
	switch instr := instr.(type) {
	case *If, *Jump, *Return, *Panic:
		s.errorf("control flow instruction not at end of block")
	case *Phi:
		if idx == 0 {
			// It suffices to apply this check to just the first phi node.
			if dup := findDuplicate(s.block.Preds); dup != nil {
				s.errorf("phi node in block with duplicate predecessor %s", dup)
			}
		} else {
			prev := s.block.Instrs[idx-1]
			if _, ok := prev.(*Phi); !ok {
				s.errorf("Phi instruction follows a non-Phi: %T", prev)
			}
		}
		if ne, np := len(instr.Edges), len(s.block.Preds); ne != np {
			s.errorf("phi node has %d edges but %d predecessors", ne, np)

		} else {
			for i, e := range instr.Edges {
				if e == nil {
					s.errorf("phi node '%s' has no value for edge #%d from %s", instr.Comment, i, s.block.Preds[i])
				} else if !types.Identical(instr.typ, e.Type()) {
					s.errorf("phi node '%s' has a different type (%s) for edge #%d from %s (%s)",
						instr.Comment, instr.Type(), i, s.block.Preds[i], e.Type())
				}
			}
		}

	case *Alloc:
		if !instr.Heap {
			found := slices.Contains(s.fn.Locals, instr)
			if !found {
				s.errorf("local alloc %s = %s does not appear in Function.Locals", instr.Name(), instr)
			}
		}

	case *BinOp:
	case *Call:
		if common := instr.Call; common.IsInvoke() {
			if !types.IsInterface(common.Value.Type()) {
				s.errorf("invoke on %s (%s) which is not an interface type (or type param)", common.Value, common.Value.Type())
			}
		}
	case *ChangeInterface:
	case *ChangeType:
	case *SliceToArrayPointer:
	case *Convert:
		if from := instr.X.Type(); !isBasicConvTypes(from) {
			if to := instr.Type(); !isBasicConvTypes(to) {
				s.errorf("convert %s -> %s: at least one type must be basic (or all basic, []byte, or []rune)", from, to)
			}
		}
	case *MultiConvert:
	case *Defer:
	case *Extract:
	case *Field:
	case *FieldAddr:
	case *Go:
	case *Index:
	case *IndexAddr:
	case *Lookup:
	case *MakeChan:
	case *MakeClosure:
		numFree := len(instr.Fn.(*Function).FreeVars)
		numBind := len(instr.Bindings)
		if numFree != numBind {
			s.errorf("MakeClosure has %d Bindings for function %s with %d free vars",
				numBind, instr.Fn, numFree)

		}
		if recv := instr.Type().(*types.Signature).Recv(); recv != nil {
			s.errorf("MakeClosure's type includes receiver %s", recv.Type())
		}

	case *MakeInterface:
	case *MakeMap:
	case *MakeSlice:
	case *MapUpdate:
	case *Next:
	case *Range:
	case *RunDefers:
	case *Select:
	case *Send:
	case *Slice:
	case *Store:
	case *TypeAssert:
	case *UnOp:
	case *DebugRef:
		// TODO(adonovan): implement checks.
	default:
		panic(fmt.Sprintf("Unknown instruction type: %T", instr))
	}

	if call, ok := instr.(CallInstruction); ok {
		if call.Common().Signature() == nil {
			s.errorf("nil signature: %s", call)
		}
	}

	// Check that value-defining instructions have valid types
	// and a valid referrer list.
	if v, ok := instr.(Value); ok {
		t := v.Type()
		if t == nil {
			s.errorf("no type: %s = %s", v.Name(), v)
		} else if t == tRangeIter || t == tDeferStack {
			// not a proper type; ignore.
		} else if b, ok := t.Underlying().(*types.Basic); ok && b.Info()&types.IsUntyped != 0 {
			s.errorf("instruction has 'untyped' result: %s = %s : %s", v.Name(), v, t)
		}
		s.checkReferrerList(v)
	}

	// Untyped constants are legal as instruction Operands(),
	// for example:
	//   _ = "foo"[0]
	// or:
	//   if wordsize==64 {...}

	// All other non-Instruction Values can be found via their
	// enclosing Function or Package.
}

func (s *sanity) checkFinalInstr(instr Instruction) {
	switch instr := instr.(type) {
	case *If:
		if nsuccs := len(s.block.Succs); nsuccs != 2 {
			s.errorf("If-terminated block has %d successors; expected 2", nsuccs)
			return
		}
		if s.block.Succs[0] == s.block.Succs[1] {
			s.errorf("If-instruction has same True, False target blocks: %s", s.block.Succs[0])
			return
		}

	case *Jump:
		if nsuccs := len(s.block.Succs); nsuccs != 1 {
			s.errorf("Jump-terminated block has %d successors; expected 1", nsuccs)
			return
		}

	case *Return:
		if nsuccs := len(s.block.Succs); nsuccs != 0 {
			s.errorf("Return-terminated block has %d successors; expected none", nsuccs)
			return
		}
		if na, nf := len(instr.Results), s.fn.Signature.Results().Len(); nf != na {
			s.errorf("%d-ary return in %d-ary function", na, nf)
		}

	case *Panic:
		if nsuccs := len(s.block.Succs); nsuccs != 0 {
			s.errorf("Panic-terminated block has %d successors; expected none", nsuccs)
			return
		}

	default:
		s.errorf("non-control flow instruction at end of block")
	}
}

func (s *sanity) checkBlock(b *BasicBlock, index int) {
	s.block = b

	if b.Index != index {
		s.errorf("block has incorrect Index %d", b.Index)
	}
	if b.parent != s.fn {
		s.errorf("block has incorrect parent %s", b.parent)
	}

	// Check all blocks are reachable.
	// (The entry block is always implicitly reachable,
	// as is the Recover block, if any.)
	if (index > 0 && b != b.parent.Recover) && len(b.Preds) == 0 {
		s.warnf("unreachable block")
		if b.Instrs == nil {
			// Since this block is about to be pruned,
			// tolerating transient problems in it
			// simplifies other optimizations.
			return
		}
	}

	// Check predecessor and successor relations are dual,
	// and that all blocks in CFG belong to same function.
	for _, a := range b.Preds {
		found := slices.Contains(a.Succs, b)
		if !found {
			s.errorf("expected successor edge in predecessor %s; found only: %s", a, a.Succs)
		}
		if a.parent != s.fn {
			s.errorf("predecessor %s belongs to different function %s", a, a.parent)
		}
	}
	for _, c := range b.Succs {
		found := slices.Contains(c.Preds, b)
		if !found {
			s.errorf("expected predecessor edge in successor %s; found only: %s", c, c.Preds)
		}
		if c.parent != s.fn {
			s.errorf("successor %s belongs to different function %s", c, c.parent)
		}
	}

	// Check each instruction is sane.
	n := len(b.Instrs)
	if n == 0 {
		s.errorf("basic block contains no instructions")
	}
	var rands [10]*Value // reuse storage
	for j, instr := range b.Instrs {
		if instr == nil {
			s.errorf("nil instruction at index %d", j)
			continue
		}
		if b2 := instr.Block(); b2 == nil {
			s.errorf("nil Block() for instruction at index %d", j)
			continue
		} else if b2 != b {
			s.errorf("wrong Block() (%s) for instruction at index %d ", b2, j)
			continue
		}
		if j < n-1 {
			s.checkInstr(j, instr)
		} else {
			s.checkFinalInstr(instr)
		}

		// Check Instruction.Operands.
	operands:
		for i, op := range instr.Operands(rands[:0]) {
			if op == nil {
				s.errorf("nil operand pointer %d of %s", i, instr)
				continue
			}
			val := *op
			if val == nil {
				continue // a nil operand is ok
			}

			// Check that "untyped" types only appear on constant operands.
			if _, ok := (*op).(*Const); !ok {
				if basic, ok := (*op).Type().Underlying().(*types.Basic); ok {
					if basic.Info()&types.IsUntyped != 0 {
						s.errorf("operand #%d of %s is untyped: %s", i, instr, basic)
					}
				}
			}

			// Check that Operands that are also Instructions belong to same function.
			// TODO(adonovan): also check their block dominates block b.
			if val, ok := val.(Instruction); ok {
				if val.Block() == nil {
					s.errorf("operand %d of %s is an instruction (%s) that belongs to no block", i, instr, val)
				} else if val.Parent() != s.fn {
					s.errorf("operand %d of %s is an instruction (%s) from function %s", i, instr, val, val.Parent())
				}
			}

			// Check that each function-local operand of
			// instr refers back to instr.  (NB: quadratic)
			switch val := val.(type) {
			case *Const, *Global, *Builtin:
				continue // not local
			case *Function:
				if val.parent == nil {
					continue // only anon functions are local
				}
			}

			// TODO(adonovan): check val.Parent() != nil <=> val.Referrers() is defined.

			if refs := val.Referrers(); refs != nil {
				for _, ref := range *refs {
					if ref == instr {
						continue operands
					}
				}
				s.errorf("operand %d of %s (%s) does not refer to us", i, instr, val)
			} else {
				s.errorf("operand %d of %s (%s) has no referrers", i, instr, val)
			}
		}
	}
}

func (s *sanity) checkReferrerList(v Value) {
	refs := v.Referrers()
	if refs == nil {
		s.errorf("%s has missing referrer list", v.Name())
		return
	}
	for i, ref := range *refs {
		if _, ok := s.instrs[ref]; !ok {
			s.errorf("%s.Referrers()[%d] = %s is not an instruction belonging to this function", v.Name(), i, ref)
		}
	}
}

func (s *sanity) checkFunctionParams() {
	signature := s.fn.Signature
	params := s.fn.Params

	// startSigParams is the start of signature.Params() within params.
	startSigParams := 0
	if signature.Recv() != nil {
		startSigParams = 1
	}

	if startSigParams+signature.Params().Len() != len(params) {
		s.errorf("function has %d parameters in signature but has %d after building",
			startSigParams+signature.Params().Len(), len(params))
		return
	}

	for i, param := range params {
		var sigType types.Type
		si := i - startSigParams
		if si < 0 {
			sigType = signature.Recv().Type()
		} else {
			sigType = signature.Params().At(si).Type()
		}

		if !types.Identical(sigType, param.Type()) {
			s.errorf("expect type %s in signature but got type %s in param %d", param.Type(), sigType, i)
		}
	}
}

// checkTransientFields checks whether all transient fields of Function are cleared.
func (s *sanity) checkTransientFields() {
	fn := s.fn
	if fn.build != nil {
		s.errorf("function transient field 'build' is not nil")
	}
	if fn.currentBlock != nil {
		s.errorf("function transient field 'currentBlock' is not nil")
	}
	if fn.vars != nil {
		s.errorf("function transient field 'vars' is not nil")
	}
	if fn.results != nil {
		s.errorf("function transient field 'results' is not nil")
	}
	if fn.returnVars != nil {
		s.errorf("function transient field 'returnVars' is not nil")
	}
	if fn.targets != nil {
		s.errorf("function transient field 'targets' is not nil")
	}
	if fn.lblocks != nil {
		s.errorf("function transient field 'lblocks' is not nil")
	}
	if fn.subst != nil {
		s.errorf("function transient field 'subst' is not nil")
	}
	if fn.jump != nil {
		s.errorf("function transient field 'jump' is not nil")
	}
	if fn.deferstack != nil {
		s.errorf("function transient field 'deferstack' is not nil")
	}
	if fn.source != nil {
		s.errorf("function transient field 'source' is not nil")
	}
	if fn.exits != nil {
		s.errorf("function transient field 'exits' is not nil")
	}
	if fn.uniq != 0 {
		s.errorf("function transient field 'uniq' is not zero")
	}
}

func (s *sanity) checkFunction(fn *Function) bool {
	s.fn = fn
	s.checkFunctionParams()
	s.checkTransientFields()

	// TODO(taking): Sanity check origin, typeparams, and typeargs.
	if fn.Prog == nil {
		s.errorf("nil Prog")
	}

	var buf bytes.Buffer
	_ = fn.String()               // must not crash
	_ = fn.RelString(fn.relPkg()) // must not crash
	WriteFunction(&buf, fn)       // must not crash

	// All functions have a package, except delegates (which are
	// shared across packages, or duplicated as weak symbols in a
	// separate-compilation model), and error.Error.
	if fn.Pkg == nil {
		if strings.HasPrefix(fn.Synthetic, "from type information (on demand)") ||
			strings.HasPrefix(fn.Synthetic, "wrapper ") ||
			strings.HasPrefix(fn.Synthetic, "bound ") ||
			strings.HasPrefix(fn.Synthetic, "thunk ") ||
			strings.HasSuffix(fn.name, "Error") ||
			strings.HasPrefix(fn.Synthetic, "instance ") ||
			strings.HasPrefix(fn.Synthetic, "instantiation ") ||
			(fn.parent != nil && len(fn.typeargs) > 0) /* anon fun in instance */ {
			// ok
		} else {
			s.errorf("nil Pkg")
		}
	}
	if src, syn := fn.Synthetic == "", fn.Syntax() != nil; src != syn {
		if len(fn.typeargs) > 0 && fn.Prog.mode&InstantiateGenerics != 0 {
			// ok (instantiation with InstantiateGenerics on)
		} else if fn.topLevelOrigin != nil && len(fn.typeargs) > 0 {
			// ok (we always have the syntax set for instantiation)
		} else if _, rng := fn.syntax.(*ast.RangeStmt); rng && fn.Synthetic == "range-over-func yield" {
			// ok (range-func-yields are both synthetic and keep syntax)
		} else {
			s.errorf("got fromSource=%t, hasSyntax=%t; want same values", src, syn)
		}
	}

	// Build the set of valid referrers.
	s.instrs = make(map[Instruction]unit)

	// instrs are the instructions that are present in the function.
	for instr := range fn.instrs() {
		s.instrs[instr] = unit{}
	}

	// Check all Locals allocations appear in the function instruction.
	for i, l := range fn.Locals {
		if _, present := s.instrs[l]; !present {
			s.warnf("function doesn't contain Local alloc %s", l.Name())
		}

		if l.Parent() != fn {
			s.errorf("Local %s at index %d has wrong parent", l.Name(), i)
		}
		if l.Heap {
			s.errorf("Local %s at index %d has Heap flag set", l.Name(), i)
		}
	}
	for i, p := range fn.Params {
		if p.Parent() != fn {
			s.errorf("Param %s at index %d has wrong parent", p.Name(), i)
		}
		// Check common suffix of Signature and Params match type.
		if sig := fn.Signature; sig != nil {
			j := i - len(fn.Params) + sig.Params().Len() // index within sig.Params
			if j < 0 {
				continue
			}
			if !types.Identical(p.Type(), sig.Params().At(j).Type()) {
				s.errorf("Param %s at index %d has wrong type (%s, versus %s in Signature)", p.Name(), i, p.Type(), sig.Params().At(j).Type())

			}
		}
		s.checkReferrerList(p)
	}
	for i, fv := range fn.FreeVars {
		if fv.Parent() != fn {
			s.errorf("FreeVar %s at index %d has wrong parent", fv.Name(), i)
		}
		s.checkReferrerList(fv)
	}

	if fn.Blocks != nil && len(fn.Blocks) == 0 {
		// Function _had_ blocks (so it's not external) but
		// they were "optimized" away, even the entry block.
		s.errorf("Blocks slice is non-nil but empty")
	}
	for i, b := range fn.Blocks {
		if b == nil {
			s.warnf("nil *BasicBlock at f.Blocks[%d]", i)
			continue
		}
		s.checkBlock(b, i)
	}
	if fn.Recover != nil && fn.Blocks[fn.Recover.Index] != fn.Recover {
		s.errorf("Recover block is not in Blocks slice")
	}

	s.block = nil
	for i, anon := range fn.AnonFuncs {
		if anon.Parent() != fn {
			s.errorf("AnonFuncs[%d]=%s but %s.Parent()=%s", i, anon, anon, anon.Parent())
		}
		if i != int(anon.anonIdx) {
			s.errorf("AnonFuncs[%d]=%s but %s.anonIdx=%d", i, anon, anon, anon.anonIdx)
		}
	}
	s.fn = nil
	return !s.insane
}

// sanityCheckPackage checks invariants of packages upon creation.
// It does not require that the package is built.
// Unlike sanityCheck (for functions), it just panics at the first error.
func sanityCheckPackage(pkg *Package) {
	if pkg.Pkg == nil {
		panic(fmt.Sprintf("Package %s has no Object", pkg))
	}
	if pkg.info != nil {
		panic(fmt.Sprintf("package %s field 'info' is not cleared", pkg))
	}
	if pkg.files != nil {
		panic(fmt.Sprintf("package %s field 'files' is not cleared", pkg))
	}
	if pkg.created != nil {
		panic(fmt.Sprintf("package %s field 'created' is not cleared", pkg))
	}
	if pkg.initVersion != nil {
		panic(fmt.Sprintf("package %s field 'initVersion' is not cleared", pkg))
	}

	_ = pkg.String() // must not crash

	for name, mem := range pkg.Members {
		if name != mem.Name() {
			panic(fmt.Sprintf("%s: %T.Name() = %s, want %s",
				pkg.Pkg.Path(), mem, mem.Name(), name))
		}
		obj := mem.Object()
		if obj == nil {
			// This check is sound because fields
			// {Global,Function}.object have type
			// types.Object.  (If they were declared as
			// *types.{Var,Func}, we'd have a non-empty
			// interface containing a nil pointer.)

			continue // not all members have typechecker objects
		}
		if obj.Name() != name {
			if obj.Name() == "init" && strings.HasPrefix(mem.Name(), "init#") {
				// Ok.  The name of a declared init function varies between
				// its types.Func ("init") and its ssa.Function ("init#%d").
			} else {
				panic(fmt.Sprintf("%s: %T.Object().Name() = %s, want %s",
					pkg.Pkg.Path(), mem, obj.Name(), name))
			}
		}
		if obj.Pos() != mem.Pos() {
			panic(fmt.Sprintf("%s Pos=%d obj.Pos=%d", mem, mem.Pos(), obj.Pos()))
		}
	}
}


================================================
FILE: go/ssa/source.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines utilities for working with source positions
// or source-level named entities ("objects").

// TODO(adonovan): test that {Value,Instruction}.Pos() positions match
// the originating syntax, as specified.

import (
	"go/ast"
	"go/token"
	"go/types"
)

// EnclosingFunction returns the function that contains the syntax
// node denoted by path.
//
// Syntax associated with package-level variable specifications is
// enclosed by the package's init() function.
//
// Returns nil if not found; reasons might include:
//   - the node is not enclosed by any function.
//   - the node is within an anonymous function (FuncLit) and
//     its SSA function has not been created yet
//     (pkg.Build() has not yet been called).
func EnclosingFunction(pkg *Package, path []ast.Node) *Function {
	// Start with package-level function...
	fn := findEnclosingPackageLevelFunction(pkg, path)
	if fn == nil {
		return nil // not in any function
	}

	// ...then walk down the nested anonymous functions.
	n := len(path)
outer:
	for i := range path {
		if lit, ok := path[n-1-i].(*ast.FuncLit); ok {
			for _, anon := range fn.AnonFuncs {
				if anon.Pos() == lit.Type.Func {
					fn = anon
					continue outer
				}
			}
			// SSA function not found:
			// - package not yet built, or maybe
			// - builder skipped FuncLit in dead block
			//   (in principle; but currently the Builder
			//   generates even dead FuncLits).
			return nil
		}
	}
	return fn
}

// HasEnclosingFunction returns true if the AST node denoted by path
// is contained within the declaration of some function or
// package-level variable.
//
// Unlike EnclosingFunction, the behaviour of this function does not
// depend on whether SSA code for pkg has been built, so it can be
// used to quickly reject check inputs that will cause
// EnclosingFunction to fail, prior to SSA building.
func HasEnclosingFunction(pkg *Package, path []ast.Node) bool {
	return findEnclosingPackageLevelFunction(pkg, path) != nil
}

// findEnclosingPackageLevelFunction returns the Function
// corresponding to the package-level function enclosing path.
func findEnclosingPackageLevelFunction(pkg *Package, path []ast.Node) *Function {
	if n := len(path); n >= 2 { // [... {Gen,Func}Decl File]
		switch decl := path[n-2].(type) {
		case *ast.GenDecl:
			if decl.Tok == token.VAR && n >= 3 {
				// Package-level 'var' initializer.
				return pkg.init
			}

		case *ast.FuncDecl:
			if decl.Recv == nil && decl.Name.Name == "init" {
				// Explicit init() function.
				for _, b := range pkg.init.Blocks {
					for _, instr := range b.Instrs {
						if instr, ok := instr.(*Call); ok {
							if callee, ok := instr.Call.Value.(*Function); ok && callee.Pkg == pkg && callee.Pos() == decl.Name.NamePos {
								return callee
							}
						}
					}
				}
				// Hack: return non-nil when SSA is not yet
				// built so that HasEnclosingFunction works.
				return pkg.init
			}
			// Declared function/method.
			return findNamedFunc(pkg, decl.Name.NamePos)
		}
	}
	return nil // not in any function
}

// findNamedFunc returns the named function whose FuncDecl.Ident is at
// position pos.
func findNamedFunc(pkg *Package, pos token.Pos) *Function {
	// Look at all package members and method sets of named types.
	// Not very efficient.
	for _, mem := range pkg.Members {
		switch mem := mem.(type) {
		case *Function:
			if mem.Pos() == pos {
				return mem
			}
		case *Type:
			mset := pkg.Prog.MethodSets.MethodSet(types.NewPointer(mem.Type()))
			for i, n := 0, mset.Len(); i < n; i++ {
				// Don't call Program.Method: avoid creating wrappers.
				obj := mset.At(i).Obj().(*types.Func)
				if obj.Pos() == pos {
					// obj from MethodSet may not be the origin type.
					m := obj.Origin()
					return pkg.objects[m].(*Function)
				}
			}
		}
	}
	return nil
}

// ValueForExpr returns the SSA Value that corresponds to non-constant
// expression e.
//
// It returns nil if no value was found, e.g.
//   - the expression is not lexically contained within f;
//   - f was not built with debug information; or
//   - e is a constant expression.  (For efficiency, no debug
//     information is stored for constants. Use
//     go/types.Info.Types[e].Value instead.)
//   - e is a reference to nil or a built-in function.
//   - the value was optimised away.
//
// If e is an addressable expression used in an lvalue context,
// value is the address denoted by e, and isAddr is true.
//
// The types of e (or &e, if isAddr) and the result are equal
// (modulo "untyped" bools resulting from comparisons).
//
// (Tip: to find the ssa.Value given a source position, use
// astutil.PathEnclosingInterval to locate the ast.Node, then
// EnclosingFunction to locate the Function, then ValueForExpr to find
// the ssa.Value.)
func (f *Function) ValueForExpr(e ast.Expr) (value Value, isAddr bool) {
	if f.debugInfo() { // (opt)
		e = ast.Unparen(e)
		for _, b := range f.Blocks {
			for _, instr := range b.Instrs {
				if ref, ok := instr.(*DebugRef); ok {
					if ref.Expr == e {
						return ref.X, ref.IsAddr
					}
				}
			}
		}
	}
	return
}

// --- Lookup functions for source-level named entities (types.Objects) ---

// Package returns the SSA Package corresponding to the specified
// type-checker package. It returns nil if no such Package was
// created by a prior call to prog.CreatePackage.
func (prog *Program) Package(pkg *types.Package) *Package {
	return prog.packages[pkg]
}

// packageLevelMember returns the package-level member corresponding
// to the specified symbol, which may be a package-level const
// (*NamedConst), var (*Global) or func/method (*Function) of some
// package in prog.
//
// It returns nil if the object belongs to a package that has not been
// created by prog.CreatePackage.
func (prog *Program) packageLevelMember(obj types.Object) Member {
	if pkg, ok := prog.packages[obj.Pkg()]; ok {
		return pkg.objects[obj]
	}
	return nil
}

// FuncValue returns the SSA function or (non-interface) method
// denoted by the specified func symbol. It returns nil if the symbol
// denotes an interface method, or belongs to a package that was not
// created by prog.CreatePackage.
func (prog *Program) FuncValue(obj *types.Func) *Function {
	fn, _ := prog.packageLevelMember(obj).(*Function)
	return fn
}

// ConstValue returns the SSA constant denoted by the specified const symbol.
func (prog *Program) ConstValue(obj *types.Const) *Const {
	// TODO(adonovan): opt: share (don't reallocate)
	// Consts for const objects and constant ast.Exprs.

	// Universal constant? {true,false,nil}
	if obj.Parent() == types.Universe {
		return NewConst(obj.Val(), obj.Type())
	}
	// Package-level named constant?
	if v := prog.packageLevelMember(obj); v != nil {
		return v.(*NamedConst).Value
	}
	return NewConst(obj.Val(), obj.Type())
}

// VarValue returns the SSA Value that corresponds to a specific
// identifier denoting the specified var symbol.
//
// VarValue returns nil if a local variable was not found, perhaps
// because its package was not built, the debug information was not
// requested during SSA construction, or the value was optimized away.
//
// ref is the path to an ast.Ident (e.g. from PathEnclosingInterval),
// and that ident must resolve to obj.
//
// pkg is the package enclosing the reference.  (A reference to a var
// always occurs within a function, so we need to know where to find it.)
//
// If the identifier is a field selector and its base expression is
// non-addressable, then VarValue returns the value of that field.
// For example:
//
//	func f() struct {x int}
//	f().x  // VarValue(x) returns a *Field instruction of type int
//
// All other identifiers denote addressable locations (variables).
// For them, VarValue may return either the variable's address or its
// value, even when the expression is evaluated only for its value; the
// situation is reported by isAddr, the second component of the result.
//
// If !isAddr, the returned value is the one associated with the
// specific identifier.  For example,
//
//	var x int    // VarValue(x) returns Const 0 here
//	x = 1        // VarValue(x) returns Const 1 here
//
// It is not specified whether the value or the address is returned in
// any particular case, as it may depend upon optimizations performed
// during SSA code generation, such as registerization, constant
// folding, avoidance of materialization of subexpressions, etc.
func (prog *Program) VarValue(obj *types.Var, pkg *Package, ref []ast.Node) (value Value, isAddr bool) {
	// All references to a var are local to some function, possibly init.
	fn := EnclosingFunction(pkg, ref)
	if fn == nil {
		return // e.g. def of struct field; SSA not built?
	}

	id := ref[0].(*ast.Ident)

	// Defining ident of a parameter?
	if id.Pos() == obj.Pos() {
		for _, param := range fn.Params {
			if param.Object() == obj {
				return param, false
			}
		}
	}

	// Other ident?
	for _, b := range fn.Blocks {
		for _, instr := range b.Instrs {
			if dr, ok := instr.(*DebugRef); ok {
				if dr.Pos() == id.Pos() {
					return dr.X, dr.IsAddr
				}
			}
		}
	}

	// Defining ident of package-level var?
	if v := prog.packageLevelMember(obj); v != nil {
		return v.(*Global), true
	}

	return // e.g. debug info not requested, or var optimized away
}


================================================
FILE: go/ssa/source_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa_test

// This file defines tests of source-level debugging utilities.

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"os"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/internal/expect"
)

func TestObjValueLookup(t *testing.T) {
	if runtime.GOOS == "android" {
		t.Skipf("no testdata directory on %s", runtime.GOOS)
	}

	src, err := os.ReadFile("testdata/objlookup.go")
	if err != nil {
		t.Fatal(err)
	}
	readFile := func(filename string) ([]byte, error) { return src, nil }

	var (
		mode          = ssa.GlobalDebug /*|ssa.PrintFunctions*/
		mainPkg, ppkg = buildPackage(t, string(src), mode)
		f             = ppkg.Syntax[0]
		tokFile       = ppkg.Fset.File(f.Pos())
	)

	// Maps each var Ident (represented "name:linenum") to the
	// kind of ssa.Value we expect (represented "Constant", "&Alloc").
	expectations := make(map[string]string)

	// Each note of the form @ssa(x, "BinOp") in testdata/objlookup.go
	// specifies an expectation that an object named x declared on the
	// same line is associated with an ssa.Value of type *ssa.BinOp.
	notes, err := expect.ExtractGo(tokFile, f)
	if err != nil {
		t.Fatal(err)
	}
	for _, n := range notes {
		if n.Name != "ssa" {
			t.Errorf("%v: unexpected note type %q, want \"ssa\"", tokFile.Position(n.Pos), n.Name)
			continue
		}
		if len(n.Args) != 2 {
			t.Errorf("%v: ssa has %d args, want 2", tokFile.Position(n.Pos), len(n.Args))
			continue
		}
		ident, ok := n.Args[0].(expect.Identifier)
		if !ok {
			t.Errorf("%v: got %v for arg 1, want identifier", tokFile.Position(n.Pos), n.Args[0])
			continue
		}
		exp, ok := n.Args[1].(string)
		if !ok {
			t.Errorf("%v: got %v for arg 2, want string", tokFile.Position(n.Pos), n.Args[1])
			continue
		}
		p, _, err := expect.MatchBefore(tokFile, readFile, n.Pos, string(ident))
		if err != nil {
			t.Error(err)
			continue
		}
		pos := tokFile.Position(p)
		key := fmt.Sprintf("%s:%d", ident, pos.Line)
		expectations[key] = exp
	}

	var varIds []*ast.Ident
	var varObjs []*types.Var
	for id, obj := range ppkg.TypesInfo.Defs {
		// Check invariants for func and const objects.
		switch obj := obj.(type) {
		case *types.Func:
			checkFuncValue(t, mainPkg.Prog, obj)

		case *types.Const:
			checkConstValue(t, mainPkg.Prog, obj)

		case *types.Var:
			if id.Name == "_" {
				continue
			}
			varIds = append(varIds, id)
			varObjs = append(varObjs, obj)
		}
	}
	for id, obj := range ppkg.TypesInfo.Uses {
		if obj, ok := obj.(*types.Var); ok {
			varIds = append(varIds, id)
			varObjs = append(varObjs, obj)
		}
	}

	// Check invariants for var objects.
	// The result varies based on the specific Ident.
	for i, id := range varIds {
		obj := varObjs[i]
		ref, _ := astutil.PathEnclosingInterval(f, id.Pos(), id.Pos())
		pos := tokFile.Position(id.Pos())
		exp := expectations[fmt.Sprintf("%s:%d", id.Name, pos.Line)]
		if exp == "" {
			t.Errorf("%s: no expectation for var ident %s ", pos, id.Name)
			continue
		}
		wantAddr := false
		if exp[0] == '&' {
			wantAddr = true
			exp = exp[1:]
		}
		checkVarValue(t, mainPkg, ref, obj, exp, wantAddr)
	}
}

func checkFuncValue(t *testing.T, prog *ssa.Program, obj *types.Func) {
	fn := prog.FuncValue(obj)
	// fmt.Printf("FuncValue(%s) = %s\n", obj, fn) // debugging
	if fn == nil {
		if obj.Name() != "interfaceMethod" {
			t.Errorf("FuncValue(%s) == nil", obj)
		}
		return
	}
	if fnobj := fn.Object(); fnobj != obj {
		t.Errorf("FuncValue(%s).Object() == %s; value was %s",
			obj, fnobj, fn.Name())
		return
	}
	if !types.Identical(fn.Type(), obj.Type()) {
		t.Errorf("FuncValue(%s).Type() == %s", obj, fn.Type())
		return
	}
}

func checkConstValue(t *testing.T, prog *ssa.Program, obj *types.Const) {
	c := prog.ConstValue(obj)
	// fmt.Printf("ConstValue(%s) = %s\n", obj, c) // debugging
	if c == nil {
		t.Errorf("ConstValue(%s) == nil", obj)
		return
	}
	if !types.Identical(c.Type(), obj.Type()) {
		t.Errorf("ConstValue(%s).Type() == %s", obj, c.Type())
		return
	}
	if obj.Name() != "nil" {
		if !constant.Compare(c.Value, token.EQL, obj.Val()) {
			t.Errorf("ConstValue(%s).Value (%s) != %s",
				obj, c.Value, obj.Val())
			return
		}
	}
}

func checkVarValue(t *testing.T, pkg *ssa.Package, ref []ast.Node, obj *types.Var, expKind string, wantAddr bool) {
	// The prefix of all assertions messages.
	prefix := fmt.Sprintf("VarValue(%s @ L%d)",
		obj, pkg.Prog.Fset.Position(ref[0].Pos()).Line)

	v, gotAddr := pkg.Prog.VarValue(obj, pkg, ref)

	// Kind is the concrete type of the ssa Value.
	gotKind := "nil"
	if v != nil {
		gotKind = fmt.Sprintf("%T", v)[len("*ssa."):]
	}

	// fmt.Printf("%s = %v (kind %q; expect %q) wantAddr=%t gotAddr=%t\n", prefix, v, gotKind, expKind, wantAddr, gotAddr) // debugging

	// Check the kinds match.
	// "nil" indicates expected failure (e.g. optimized away).
	if expKind != gotKind {
		t.Errorf("%s concrete type == %s, want %s", prefix, gotKind, expKind)
	}

	// Check the types match.
	// If wantAddr, the expected type is the object's address.
	if v != nil {
		expType := obj.Type()
		if wantAddr {
			expType = types.NewPointer(expType)
			if !gotAddr {
				t.Errorf("%s: got value, want address", prefix)
			}
		} else if gotAddr {
			t.Errorf("%s: got address, want value", prefix)
		}
		if !types.Identical(v.Type(), expType) {
			t.Errorf("%s.Type() == %s, want %s", prefix, v.Type(), expType)
		}
	}
}

// Ensure that, in debug mode, we can determine the ssa.Value
// corresponding to every ast.Expr.
func TestValueForExpr(t *testing.T) {
	testValueForExpr(t, "testdata/valueforexpr.go")
}

func TestValueForExprStructConv(t *testing.T) {
	testValueForExpr(t, "testdata/structconv.go")
}

func testValueForExpr(t *testing.T, testfile string) {
	if runtime.GOOS == "android" {
		t.Skipf("no testdata dir on %s", runtime.GOOS)
	}

	src, err := os.ReadFile(testfile)
	if err != nil {
		t.Fatal(err)
	}

	var (
		mode          = ssa.GlobalDebug /*|ssa.PrintFunctions*/
		mainPkg, ppkg = buildPackage(t, string(src), mode)
		file          = ppkg.Syntax[0]
		tokFile       = ppkg.Fset.File(file.Pos())
	)

	if false {
		// debugging
		for _, mem := range mainPkg.Members {
			if fn, ok := mem.(*ssa.Function); ok {
				fn.WriteTo(os.Stderr)
			}
		}
	}

	var parenExprs []*ast.ParenExpr
	ast.Inspect(file, func(n ast.Node) bool {
		if n != nil {
			if e, ok := n.(*ast.ParenExpr); ok {
				parenExprs = append(parenExprs, e)
			}
		}
		return true
	})

	notes, err := expect.ExtractGo(tokFile, file)
	if err != nil {
		t.Fatal(err)
	}
	for _, n := range notes {
		want := n.Name
		if want == "nil" {
			want = "<nil>"
		}
		position := tokFile.Position(n.Pos)
		var e ast.Expr
		for _, paren := range parenExprs {
			if paren.Pos() > n.Pos {
				e = paren.X
				break
			}
		}
		if e == nil {
			t.Errorf("%s: note doesn't precede ParenExpr: %q", position, want)
			continue
		}

		path, _ := astutil.PathEnclosingInterval(file, n.Pos, n.Pos)
		if path == nil {
			t.Errorf("%s: can't find AST path from root to comment: %s", position, want)
			continue
		}

		fn := ssa.EnclosingFunction(mainPkg, path)
		if fn == nil {
			t.Errorf("%s: can't find enclosing function", position)
			continue
		}

		v, gotAddr := fn.ValueForExpr(e) // (may be nil)
		got := strings.TrimPrefix(fmt.Sprintf("%T", v), "*ssa.")
		if got != want {
			t.Errorf("%s: got value %q, want %q", position, got, want)
		}
		if v != nil {
			T := v.Type()
			if gotAddr {
				T = T.Underlying().(*types.Pointer).Elem() // deref
			}
			if etyp := ppkg.TypesInfo.TypeOf(e); !types.Identical(T, etyp) {
				t.Errorf("%s: got type %s, want %s", position, etyp, T)
			}
		}
	}
}

func TestEnclosingFunction(t *testing.T) {
	tests := []struct {
		desc   string
		input  string // the input file
		substr string // first occurrence of this string denotes interval
		fn     string // name of expected containing function
	}{
		// We use distinctive numbers as syntactic landmarks.
		{"Ordinary function", `
		  package main
		  func f() { println(1003) }`,
			"100", "main.f"},
		{"Methods", `
		  package main
          type T int
		  func (t T) f() { println(200) }`,
			"200", "(main.T).f"},
		{"Function literal", `
		  package main
		  func f() { println(func() { print(300) }) }`,
			"300", "main.f$1"},
		{"Doubly nested", `
		  package main
		  func f() { println(func() { print(func() { print(350) })})}`,
			"350", "main.f$1$1"},
		{"Implicit init for package-level var initializer", `
		  package main; var a = 400`,
			"400", "main.init"},
		{"No code for constants", "package main; const a = 500", "500", "(none)"},
		{" Explicit init", "package main; func init() { println(600) }", "600", "main.init#1"},
		{"Multiple explicit init functions", `
		  package main
		  func init() { println("foo") }
		  func init() { println(800) }`,
			"800", "main.init#2"},
		{"init containing FuncLit", `
		  package main
		  func init() { println(func(){print(900)}) }`,
			"900", "main.init#1$1"},
		{"generic", `
		    package main
			type S[T any] struct{}
			func (*S[T]) Foo() { println(1000) }
			type P[T any] struct{ *S[T] }`,
			"1000", "(*main.S[T]).Foo",
		},
	}
	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			pkg, ppkg := buildPackage(t, test.input, ssa.BuilderMode(0))
			fset, file := ppkg.Fset, ppkg.Syntax[0]

			// Find [start,end) positions of the first occurrence of substr in file.
			index := strings.Index(test.input, test.substr)
			if index < 0 {
				t.Fatalf("%q is not a substring of input", test.substr)
			}
			filePos := fset.File(file.Package)
			start, end := filePos.Pos(index), filePos.Pos(index+len(test.substr))

			path, exact := astutil.PathEnclosingInterval(file, start, end)
			if !exact {
				t.Fatalf("PathEnclosingInterval(%q) not exact", test.substr)
			}

			name := "(none)"
			fn := ssa.EnclosingFunction(pkg, path)
			if fn != nil {
				name = fn.String()
			}

			if name != test.fn {
				t.Errorf("EnclosingFunction(%q in %q) got %s, want %s",
					test.substr, test.input, name, test.fn)
			}

			// While we're here: test HasEnclosingFunction.
			if has := ssa.HasEnclosingFunction(pkg, path); has != (fn != nil) {
				t.Errorf("HasEnclosingFunction(%q in %q) got %v, want %v",
					test.substr, test.input, has, fn != nil)
			}
		})
	}
}


================================================
FILE: go/ssa/ssa.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This package defines a high-level intermediate representation for
// Go programs using static single-assignment (SSA) form.

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"sync"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
)

// A Program is a partial or complete Go program converted to SSA form.
type Program struct {
	Fset       *token.FileSet              // position information for the files of this Program
	imported   map[string]*Package         // all importable Packages, keyed by import path
	packages   map[*types.Package]*Package // all created Packages
	mode       BuilderMode                 // set of mode bits for SSA construction
	MethodSets typeutil.MethodSetCache     // cache of type-checker's method-sets

	canon *canonizer     // type canonicalization map
	ctxt  *types.Context // cache for type checking instantiations

	methodsMu  sync.Mutex
	methodSets typeutil.Map // maps type to its concrete *methodSet

	// memoization of whether a type refers to type parameters
	hasParamsMu sync.Mutex
	hasParams   typeparams.Free

	// set of concrete types used as MakeInterface operands
	makeInterfaceTypesMu sync.Mutex
	makeInterfaceTypes   map[types.Type]unit // (may contain redundant identical types)

	// objectMethods is a memoization of objectMethod
	// to avoid creation of duplicate methods from type information.
	objectMethodsMu sync.Mutex
	objectMethods   map[*types.Func]*Function

	noReturn func(*types.Func) bool // (optional) predicate that decides whether a given call cannot return
}

// A Package is a single analyzed Go package containing Members for
// all package-level functions, variables, constants and types it
// declares.  These may be accessed directly via Members, or via the
// type-specific accessor methods Func, Type, Var and Const.
//
// Members also contains entries for "init" (the synthetic package
// initializer) and "init#%d", the nth declared init function,
// and unspecified other things too.
type Package struct {
	Prog    *Program                // the owning program
	Pkg     *types.Package          // the corresponding go/types.Package
	Members map[string]Member       // all package members keyed by name (incl. init and init#%d)
	objects map[types.Object]Member // mapping of package objects to members (incl. methods). Contains *NamedConst, *Global, *Function (values but not types)
	init    *Function               // Func("init"); the package's init function
	debug   bool                    // include full debug info in this package
	syntax  bool                    // package was loaded from syntax

	// The following fields are set transiently, then cleared
	// after building.
	buildOnce   sync.Once           // ensures package building occurs once
	ninit       int32               // number of init functions
	info        *types.Info         // package type information
	files       []*ast.File         // package ASTs
	created     []*Function         // members created as a result of building this package (includes declared functions, wrappers)
	initVersion map[ast.Expr]string // goversion to use for each global var init expr
}

// A Member is a member of a Go package, implemented by *NamedConst,
// *Global, *Function, or *Type; they are created by package-level
// const, var, func and type declarations respectively.
type Member interface {
	Name() string                    // declared name of the package member
	String() string                  // package-qualified name of the package member
	RelString(*types.Package) string // like String, but relative refs are unqualified
	Object() types.Object            // typechecker's object for this member, if any
	Pos() token.Pos                  // position of member's declaration, if known
	Type() types.Type                // type of the package member
	Token() token.Token              // token.{VAR,FUNC,CONST,TYPE}
	Package() *Package               // the containing package
}

// A Type is a Member of a Package representing a package-level named type.
type Type struct {
	object *types.TypeName
	pkg    *Package
}

// A NamedConst is a Member of a Package representing a package-level
// named constant.
//
// Pos() returns the position of the declaring ast.ValueSpec.Names[*]
// identifier.
//
// NB: a NamedConst is not a Value; it contains a constant Value, which
// it augments with the name and position of its 'const' declaration.
type NamedConst struct {
	object *types.Const
	Value  *Const
	pkg    *Package
}

// A Value is an SSA value that can be referenced by an instruction.
type Value interface {
	// Name returns the name of this value, and determines how
	// this Value appears when used as an operand of an
	// Instruction.
	//
	// This is the same as the source name for Parameters,
	// Builtins, Functions, FreeVars, Globals.
	// For constants, it is a representation of the constant's value
	// and type.  For all other Values this is the name of the
	// virtual register defined by the instruction.
	//
	// The name of an SSA Value is not semantically significant,
	// and may not even be unique within a function.
	Name() string

	// If this value is an Instruction, String returns its
	// disassembled form; otherwise it returns unspecified
	// human-readable information about the Value, such as its
	// kind, name and type.
	String() string

	// Type returns the type of this value.  Many instructions
	// (e.g. IndexAddr) change their behaviour depending on the
	// types of their operands.
	Type() types.Type

	// Parent returns the function to which this Value belongs.
	// It returns nil for named Functions, Builtin, Const and Global.
	Parent() *Function

	// Referrers returns the list of instructions that have this
	// value as one of their operands; it may contain duplicates
	// if an instruction has a repeated operand.
	//
	// Referrers actually returns a pointer through which the
	// caller may perform mutations to the object's state.
	//
	// Referrers is currently only defined if Parent()!=nil,
	// i.e. for the function-local values FreeVar, Parameter,
	// Functions (iff anonymous) and all value-defining instructions.
	// It returns nil for named Functions, Builtin, Const and Global.
	//
	// Instruction.Operands contains the inverse of this relation.
	Referrers() *[]Instruction

	// Pos returns the location of the AST token most closely
	// associated with the operation that gave rise to this value,
	// or token.NoPos if it was not explicit in the source.
	//
	// For each ast.Node type, a particular token is designated as
	// the closest location for the expression, e.g. the Lparen
	// for an *ast.CallExpr.  This permits a compact but
	// approximate mapping from Values to source positions for use
	// in diagnostic messages, for example.
	//
	// (Do not use this position to determine which Value
	// corresponds to an ast.Expr; use Function.ValueForExpr
	// instead.  NB: it requires that the function was built with
	// debug information.)
	Pos() token.Pos
}

// An Instruction is an SSA instruction that computes a new Value or
// has some effect.
//
// An Instruction that defines a value (e.g. BinOp) also implements
// the Value interface; an Instruction that only has an effect (e.g. Store)
// does not.
type Instruction interface {
	// String returns the disassembled form of this value.
	//
	// Examples of Instructions that are Values:
	//       "x + y"     (BinOp)
	//       "len([])"   (Call)
	// Note that the name of the Value is not printed.
	//
	// Examples of Instructions that are not Values:
	//       "return x"  (Return)
	//       "*y = x"    (Store)
	//
	// (The separation Value.Name() from Value.String() is useful
	// for some analyses which distinguish the operation from the
	// value it defines, e.g., 'y = local int' is both an allocation
	// of memory 'local int' and a definition of a pointer y.)
	String() string

	// Parent returns the function to which this instruction
	// belongs.
	Parent() *Function

	// Block returns the basic block to which this instruction
	// belongs.
	Block() *BasicBlock

	// setBlock sets the basic block to which this instruction belongs.
	setBlock(*BasicBlock)

	// Operands returns the operands of this instruction: the
	// set of Values it references.
	//
	// Specifically, it appends their addresses to rands, a
	// user-provided slice, and returns the resulting slice,
	// permitting avoidance of memory allocation.
	//
	// The operands are appended in undefined order, but the order
	// is consistent for a given Instruction; the addresses are
	// always non-nil but may point to a nil Value.  Clients may
	// store through the pointers, e.g. to effect a value
	// renaming.
	//
	// Value.Referrers is a subset of the inverse of this
	// relation.  (Referrers are not tracked for all types of
	// Values.)
	Operands(rands []*Value) []*Value

	// Pos returns the location of the AST token most closely
	// associated with the operation that gave rise to this
	// instruction, or token.NoPos if it was not explicit in the
	// source.
	//
	// For each ast.Node type, a particular token is designated as
	// the closest location for the expression, e.g. the Go token
	// for an *ast.GoStmt.  This permits a compact but approximate
	// mapping from Instructions to source positions for use in
	// diagnostic messages, for example.
	//
	// (Do not use this position to determine which Instruction
	// corresponds to an ast.Expr; see the notes for Value.Pos.
	// This position may be used to determine which non-Value
	// Instruction corresponds to some ast.Stmts, but not all: If
	// and Jump instructions have no Pos(), for example.)
	Pos() token.Pos
}

// A Node is a node in the SSA value graph.  Every concrete type that
// implements Node is also either a Value, an Instruction, or both.
//
// Node contains the methods common to Value and Instruction, plus the
// Operands and Referrers methods generalized to return nil for
// non-Instructions and non-Values, respectively.
//
// Node is provided to simplify SSA graph algorithms.  Clients should
// use the more specific and informative Value or Instruction
// interfaces where appropriate.
type Node interface {
	// Common methods:
	String() string
	Pos() token.Pos
	Parent() *Function

	// Partial methods:
	Operands(rands []*Value) []*Value // nil for non-Instructions
	Referrers() *[]Instruction        // nil for non-Values
}

// Function represents the parameters, results, and code of a function
// or method.
//
// If Blocks is nil, this indicates an external function for which no
// Go source code is available.  In this case, FreeVars, Locals, and
// Params are nil too.  Clients performing whole-program analysis must
// handle external functions specially.
//
// Blocks contains the function's control-flow graph (CFG).
// Blocks[0] is the function entry point; block order is not otherwise
// semantically significant, though it may affect the readability of
// the disassembly.
// To iterate over the blocks in dominance order, use DomPreorder().
//
// Recover is an optional second entry point to which control resumes
// after a recovered panic.  The Recover block may contain only a return
// statement, preceded by a load of the function's named return
// parameters, if any.
//
// A nested function (Parent()!=nil) that refers to one or more
// lexically enclosing local variables ("free variables") has FreeVars.
// Such functions cannot be called directly but require a
// value created by MakeClosure which, via its Bindings, supplies
// values for these parameters.
//
// If the function is a method (Signature.Recv() != nil) then the first
// element of Params is the receiver parameter.
//
// A Go package may declare many functions called "init".
// For each one, Object().Name() returns "init" but Name() returns
// "init#1", etc, in declaration order.
//
// Pos() returns the declaring ast.FuncLit.Type.Func or the position
// of the ast.FuncDecl.Name, if the function was explicit in the
// source. Synthetic wrappers, for which Synthetic != "", may share
// the same position as the function they wrap.
// Syntax.Pos() always returns the position of the declaring "func" token.
//
// When the operand of a range statement is an iterator function,
// the loop body is transformed into a synthetic anonymous function
// that is passed as the yield argument in a call to the iterator.
// In that case, Function.Pos is the position of the "range" token,
// and Function.Syntax is the ast.RangeStmt.
//
// Synthetic functions, for which Synthetic != "", are functions
// that do not appear in the source AST. These include:
//   - method wrappers,
//   - thunks,
//   - bound functions,
//   - empty functions built from loaded type information,
//   - yield functions created from range-over-func loops,
//   - package init functions, and
//   - instantiations of generic functions.
//
// Synthetic wrapper functions may share the same position
// as the function they wrap.
//
// Type() returns the function's Signature.
//
// A generic function is a function or method that has uninstantiated type
// parameters (TypeParams() != nil). Consider a hypothetical generic
// method, (*Map[K,V]).Get. It may be instantiated with all
// non-parameterized types as (*Map[string,int]).Get or with
// parameterized types as (*Map[string,U]).Get, where U is a type parameter.
// In both instantiations, Origin() refers to the instantiated generic
// method, (*Map[K,V]).Get, TypeParams() refers to the parameters [K,V] of
// the generic method. TypeArgs() refers to [string,U] or [string,int],
// respectively, and is nil in the generic method.
type Function struct {
	name      string
	object    *types.Func // symbol for declared function (nil for FuncLit or synthetic init)
	method    *selection  // info about provenance of synthetic methods; thunk => non-nil
	Signature *types.Signature
	pos       token.Pos

	// source information
	Synthetic string      // provenance of synthetic function; "" for true source functions
	syntax    ast.Node    // *ast.Func{Decl,Lit}, if from syntax (incl. generic instances) or (*ast.RangeStmt if a yield function)
	info      *types.Info // type annotations (if syntax != nil)
	goversion string      // Go version of syntax (NB: init is special)

	parent *Function // enclosing function if anon; nil if global
	Pkg    *Package  // enclosing package; nil for shared funcs (wrappers and error.Error)
	Prog   *Program  // enclosing program

	buildshared *task // wait for a shared function to be done building (may be nil if <=1 builder ever needs to wait)

	// These fields are populated only when the function body is built:

	Params    []*Parameter  // function parameters; for methods, includes receiver
	FreeVars  []*FreeVar    // free variables whose values must be supplied by closure
	Locals    []*Alloc      // frame-allocated variables of this function
	Blocks    []*BasicBlock // basic blocks of the function; nil => external
	Recover   *BasicBlock   // optional; control transfers here after recovered panic
	AnonFuncs []*Function   // anonymous functions (from FuncLit,RangeStmt) directly beneath this one
	referrers []Instruction // referring instructions (iff Parent() != nil)
	anonIdx   int32         // position of a nested function in parent's AnonFuncs. fn.Parent()!=nil => fn.Parent().AnonFunc[fn.anonIdx] == fn.

	typeparams     *types.TypeParamList // type parameters of this function. typeparams.Len() > 0 => generic or instance of generic function
	typeargs       []types.Type         // type arguments that instantiated typeparams. len(typeargs) > 0 => instance of generic function
	topLevelOrigin *Function            // the origin function if this is an instance of a source function. nil if Parent()!=nil.
	generic        *generic             // instances of this function, if generic

	// The following fields are cleared after building.
	build        buildFunc                // algorithm to build function body (nil => built)
	currentBlock *BasicBlock              // where to emit code
	vars         map[*types.Var]Value     // addresses of local variables
	results      []*Alloc                 // result allocations of the current function
	returnVars   []*types.Var             // variables for a return statement. Either results or for range-over-func a parent's results
	targets      *targets                 // linked stack of branch targets
	lblocks      map[*types.Label]*lblock // labelled blocks
	subst        *subster                 // type parameter substitutions (if non-nil)
	jump         *types.Var               // synthetic variable for the yield state (non-nil => range-over-func)
	deferstack   *types.Var               // synthetic variable holding enclosing ssa:deferstack()
	source       *Function                // nearest enclosing source function
	exits        []*exit                  // exits of the function that need to be resolved
	uniq         int64                    // source of unique ints within the source tree while building
}

// BasicBlock represents an SSA basic block.
//
// The final element of Instrs is always an explicit transfer of
// control (If, Jump, Return, or Panic).
//
// A block may contain no Instructions only if it is unreachable,
// i.e., Preds is nil.  Empty blocks are typically pruned.
//
// BasicBlocks and their Preds/Succs relation form a (possibly cyclic)
// graph independent of the SSA Value graph: the control-flow graph or
// CFG.  It is illegal for multiple edges to exist between the same
// pair of blocks.
//
// Each BasicBlock is also a node in the dominator tree of the CFG.
// The tree may be navigated using Idom()/Dominees() and queried using
// Dominates().
//
// The order of Preds and Succs is significant (to Phi and If
// instructions, respectively).
type BasicBlock struct {
	Index        int            // index of this block within Parent().Blocks
	Comment      string         // optional label; no semantic significance
	parent       *Function      // parent function
	Instrs       []Instruction  // instructions in order
	Preds, Succs []*BasicBlock  // predecessors and successors
	succs2       [2]*BasicBlock // initial space for Succs
	dom          domInfo        // dominator tree info
	gaps         int            // number of nil Instrs (transient)
	rundefers    int            // number of rundefers (transient)
}

// Pure values ----------------------------------------

// A FreeVar represents a free variable of the function to which it
// belongs.
//
// FreeVars are used to implement anonymous functions, whose free
// variables are lexically captured in a closure formed by
// MakeClosure.  The value of such a free var is an Alloc or another
// FreeVar and is considered a potentially escaping heap address, with
// pointer type.
//
// FreeVars are also used to implement bound method closures.  Such a
// free var represents the receiver value and may be of any type that
// has concrete methods.
//
// Pos() returns the position of the value that was captured, which
// belongs to an enclosing function.
type FreeVar struct {
	name      string
	typ       types.Type
	pos       token.Pos
	parent    *Function
	referrers []Instruction

	// Transiently needed during building.
	outer Value // the Value captured from the enclosing context.
}

// A Parameter represents an input parameter of a function.
type Parameter struct {
	name      string
	object    *types.Var // non-nil
	typ       types.Type
	parent    *Function
	referrers []Instruction
}

// A Const represents a value known at build time.
//
// Consts include true constants of boolean, numeric, and string types, as
// defined by the Go spec; these are represented by a non-nil Value field.
//
// Consts also include the "zero" value of any type, of which the nil values
// of various pointer-like types are a special case; these are represented
// by a nil Value field.
//
// Pos() returns token.NoPos.
//
// Example printed forms:
//
//		42:int
//		"hello":untyped string
//		3+4i:MyComplex
//		nil:*int
//		nil:[]string
//		[3]int{}:[3]int
//		struct{x string}{}:struct{x string}
//	    0:interface{int|int64}
//	    nil:interface{bool|int} // no go/constant representation
type Const struct {
	typ   types.Type
	Value constant.Value
}

// A Global is a named Value holding the address of a package-level
// variable.
//
// Pos() returns the position of the ast.ValueSpec.Names[*]
// identifier.
type Global struct {
	name   string
	object types.Object // a *types.Var; may be nil for synthetics e.g. init$guard
	typ    types.Type
	pos    token.Pos

	Pkg *Package
}

// A Builtin represents a specific use of a built-in function, e.g. len.
//
// Builtins are immutable values.  Builtins do not have addresses.
// Builtins can only appear in CallCommon.Value.
//
// Name() indicates the function: one of the built-in functions from the
// Go spec (excluding "make" and "new") or one of these ssa-defined
// intrinsics:
//
//	// wrapnilchk returns ptr if non-nil, panics otherwise.
//	// (For use in indirection wrappers.)
//	func ssa:wrapnilchk(ptr *T, recvType, methodName string) *T
//
// Object() returns a *types.Builtin for built-ins defined by the spec,
// nil for others.
//
// Type() returns a *types.Signature representing the effective
// signature of the built-in for this call.
type Builtin struct {
	name string
	sig  *types.Signature
}

// Value-defining instructions  ----------------------------------------

// The Alloc instruction reserves space for a variable of the given type,
// zero-initializes it, and yields its address.
//
// Alloc values are always addresses, and have pointer types, so the
// type of the allocated variable is actually
// Type().Underlying().(*types.Pointer).Elem().
//
// If Heap is false, Alloc zero-initializes the same local variable in
// the call frame and returns its address; in this case the Alloc must
// be present in Function.Locals. We call this a "local" alloc.
//
// If Heap is true, Alloc allocates a new zero-initialized variable
// each time the instruction is executed. We call this a "new" alloc.
//
// When Alloc is applied to a channel, map or slice type, it returns
// the address of an uninitialized (nil) reference of that kind; store
// the result of MakeSlice, MakeMap or MakeChan in that location to
// instantiate these types.
//
// Pos() returns the ast.CompositeLit.Lbrace for a composite literal,
// or the ast.CallExpr.Rparen for a call to new() or for a call that
// allocates a varargs slice.
//
// Example printed form:
//
//	t0 = local int
//	t1 = new int
type Alloc struct {
	register
	Comment string
	Heap    bool
	index   int // dense numbering; for lifting
}

// The Phi instruction represents an SSA φ-node, which combines values
// that differ across incoming control-flow edges and yields a new
// value.  Within a block, all φ-nodes must appear before all non-φ
// nodes.
//
// Pos() returns the position of the && or || for short-circuit
// control-flow joins, or that of the *Alloc for φ-nodes inserted
// during SSA renaming.
//
// Example printed form:
//
//	t2 = phi [0: t0, 1: t1]
type Phi struct {
	register
	Comment string  // a hint as to its purpose
	Edges   []Value // Edges[i] is value for Block().Preds[i]
}

// The Call instruction represents a function or method call.
//
// The Call instruction yields the function result if there is exactly
// one.  Otherwise it returns a tuple, the components of which are
// accessed via Extract.
//
// See CallCommon for generic function call documentation.
//
// Pos() returns the ast.CallExpr.Lparen, if explicit in the source.
//
// Example printed form:
//
//	t2 = println(t0, t1)
//	t4 = t3()
//	t7 = invoke t5.Println(...t6)
type Call struct {
	register
	Call CallCommon
}

// The BinOp instruction yields the result of binary operation X Op Y.
//
// Pos() returns the ast.BinaryExpr.OpPos, if explicit in the source.
//
// Example printed form:
//
//	t1 = t0 + 1:int
type BinOp struct {
	register
	// One of:
	// ADD SUB MUL QUO REM          + - * / %
	// AND OR XOR SHL SHR AND_NOT   & | ^ << >> &^
	// EQL NEQ LSS LEQ GTR GEQ      == != < <= < >=
	Op   token.Token
	X, Y Value
}

// The UnOp instruction yields the result of Op X.
// ARROW is channel receive.
// MUL is pointer indirection (load).
// XOR is bitwise complement.
// SUB is negation.
// NOT is logical negation.
//
// If CommaOk and Op=ARROW, the result is a 2-tuple of the value above
// and a boolean indicating the success of the receive.  The
// components of the tuple are accessed using Extract.
//
// Pos() returns the ast.UnaryExpr.OpPos, if explicit in the source.
// For receive operations (ARROW) implicit in ranging over a channel,
// Pos() returns the ast.RangeStmt.For.
// For implicit memory loads (STAR), Pos() returns the position of the
// most closely associated source-level construct; the details are not
// specified.
//
// Example printed form:
//
//	t0 = *x
//	t2 = <-t1,ok
type UnOp struct {
	register
	Op      token.Token // One of: NOT SUB ARROW MUL XOR ! - <- * ^
	X       Value
	CommaOk bool
}

// The ChangeType instruction applies to X a value-preserving type
// change to Type().
//
// Type changes are permitted:
//   - between a named type and its underlying type.
//   - between two named types of the same underlying type.
//   - between (possibly named) pointers to identical base types.
//   - from a bidirectional channel to a read- or write-channel,
//     optionally adding/removing a name.
//   - between a type (t) and an instance of the type (tσ), i.e.
//     Type() == σ(X.Type()) (or X.Type()== σ(Type())) where
//     σ is the type substitution of Parent().TypeParams by
//     Parent().TypeArgs.
//
// This operation cannot fail dynamically.
//
// Type changes may to be to or from a type parameter (or both). All
// types in the type set of X.Type() have a value-preserving type
// change to all types in the type set of Type().
//
// Pos() returns the ast.CallExpr.Lparen, if the instruction arose
// from an explicit conversion in the source.
//
// Example printed form:
//
//	t1 = changetype *int <- IntPtr (t0)
type ChangeType struct {
	register
	X Value
}

// The Convert instruction yields the conversion of value X to type
// Type().  One or both of those types is basic (but possibly named).
//
// A conversion may change the value and representation of its operand.
// Conversions are permitted:
//   - between real numeric types.
//   - between complex numeric types.
//   - between string and []byte or []rune.
//   - between pointers and unsafe.Pointer.
//   - between unsafe.Pointer and uintptr.
//   - from (Unicode) integer to (UTF-8) string.
//
// A conversion may imply a type name change also.
//
// Conversions may to be to or from a type parameter. All types in
// the type set of X.Type() can be converted to all types in the type
// set of Type().
//
// This operation cannot fail dynamically.
//
// Conversions of untyped string/number/bool constants to a specific
// representation are eliminated during SSA construction.
//
// Pos() returns the ast.CallExpr.Lparen, if the instruction arose
// from an explicit conversion in the source.
//
// Example printed form:
//
//	t1 = convert []byte <- string (t0)
type Convert struct {
	register
	X Value
}

// The MultiConvert instruction yields the conversion of value X to type
// Type(). Either X.Type() or Type() must be a type parameter. Each
// type in the type set of X.Type() can be converted to each type in the
// type set of Type().
//
// See the documentation for Convert, ChangeType, and SliceToArrayPointer
// for the conversions that are permitted. Additionally conversions of
// slices to arrays are permitted.
//
// This operation can fail dynamically (see SliceToArrayPointer).
//
// Pos() returns the ast.CallExpr.Lparen, if the instruction arose
// from an explicit conversion in the source.
//
// Example printed form:
//
//	t1 = multiconvert D <- S (t0) [*[2]rune <- []rune | string <- []rune]
type MultiConvert struct {
	register
	X        Value
	from, to types.Type
}

// ChangeInterface constructs a value of one interface type from a
// value of another interface type known to be assignable to it.
// This operation cannot fail.
//
// Pos() returns the ast.CallExpr.Lparen if the instruction arose from
// an explicit T(e) conversion; the ast.TypeAssertExpr.Lparen if the
// instruction arose from an explicit e.(T) operation; or token.NoPos
// otherwise.
//
// Example printed form:
//
//	t1 = change interface interface{} <- I (t0)
type ChangeInterface struct {
	register
	X Value
}

// The SliceToArrayPointer instruction yields the conversion of slice X to
// array pointer.
//
// Pos() returns the ast.CallExpr.Lparen, if the instruction arose
// from an explicit conversion in the source.
//
// Conversion may to be to or from a type parameter. All types in
// the type set of X.Type() must be a slice types that can be converted to
// all types in the type set of Type() which must all be pointer to array
// types.
//
// This operation can fail dynamically if the length of the slice is less
// than the length of the array.
//
// Example printed form:
//
//	t1 = slice to array pointer *[4]byte <- []byte (t0)
type SliceToArrayPointer struct {
	register
	X Value
}

// MakeInterface constructs an instance of an interface type from a
// value of a concrete type.
//
// Use Program.MethodSets.MethodSet(X.Type()) to find the method-set
// of X, and Program.MethodValue(m) to find the implementation of a method.
//
// To construct the zero value of an interface type T, use:
//
//	NewConst(constant.MakeNil(), T, pos)
//
// Pos() returns the ast.CallExpr.Lparen, if the instruction arose
// from an explicit conversion in the source.
//
// Example printed form:
//
//	t1 = make interface{} <- int (42:int)
//	t2 = make Stringer <- t0
type MakeInterface struct {
	register
	X Value
}

// The MakeClosure instruction yields a closure value whose code is
// Fn and whose free variables' values are supplied by Bindings.
//
// Type() returns a (possibly named) *types.Signature.
//
// Pos() returns the ast.FuncLit.Type.Func for a function literal
// closure or the ast.SelectorExpr.Sel for a bound method closure.
//
// Example printed form:
//
//	t0 = make closure anon@1.2 [x y z]
//	t1 = make closure bound$(main.I).add [i]
type MakeClosure struct {
	register
	Fn       Value   // always a *Function
	Bindings []Value // values for each free variable in Fn.FreeVars
}

// The MakeMap instruction creates a new hash-table-based map object
// and yields a value of kind map.
//
// Type() returns a (possibly named) *types.Map.
//
// Pos() returns the ast.CallExpr.Lparen, if created by make(map), or
// the ast.CompositeLit.Lbrack if created by a literal.
//
// Example printed form:
//
//	t1 = make map[string]int t0
//	t1 = make StringIntMap t0
type MakeMap struct {
	register
	Reserve Value // initial space reservation; nil => default
}

// The MakeChan instruction creates a new channel object and yields a
// value of kind chan.
//
// Type() returns a (possibly named) *types.Chan.
//
// Pos() returns the ast.CallExpr.Lparen for the make(chan) that
// created it.
//
// Example printed form:
//
//	t0 = make chan int 0
//	t0 = make IntChan 0
type MakeChan struct {
	register
	Size Value // int; size of buffer; zero => synchronous.
}

// The MakeSlice instruction yields a slice of length Len backed by a
// newly allocated array of length Cap.
//
// Both Len and Cap must be non-nil Values of integer type.
//
// (Alloc(types.Array) followed by Slice will not suffice because
// Alloc can only create arrays of constant length.)
//
// Type() returns a (possibly named) *types.Slice.
//
// Pos() returns the ast.CallExpr.Lparen for the make([]T) that
// created it.
//
// Example printed form:
//
//	t1 = make []string 1:int t0
//	t1 = make StringSlice 1:int t0
type MakeSlice struct {
	register
	Len Value
	Cap Value
}

// The Slice instruction yields a slice of an existing string, slice
// or *array X between optional integer bounds Low and High.
//
// Dynamically, this instruction panics if X evaluates to a nil *array
// pointer.
//
// Type() returns string if the type of X was string, otherwise a
// *types.Slice with the same element type as X.
//
// Pos() returns the ast.SliceExpr.Lbrack if created by a x[:] slice
// operation, the ast.CompositeLit.Lbrace if created by a literal, or
// NoPos if not explicit in the source (e.g. a variadic argument slice).
//
// Example printed form:
//
//	t1 = slice t0[1:]
type Slice struct {
	register
	X              Value // slice, string, or *array
	Low, High, Max Value // each may be nil
}

// The FieldAddr instruction yields the address of Field of *struct X.
//
// The field is identified by its index within the field list of the
// struct type of X.
//
// Dynamically, this instruction panics if X evaluates to a nil
// pointer.
//
// Type() returns a (possibly named) *types.Pointer.
//
// Pos() returns the position of the ast.SelectorExpr.Sel for the
// field, if explicit in the source. For implicit selections, returns
// the position of the inducing explicit selection. If produced for a
// struct literal S{f: e}, it returns the position of the colon; for
// S{e} it returns the start of expression e.
//
// Example printed form:
//
//	t1 = &t0.name [#1]
type FieldAddr struct {
	register
	X     Value // *struct
	Field int   // index into CoreType(CoreType(X.Type()).(*types.Pointer).Elem()).(*types.Struct).Fields
}

// The Field instruction yields the Field of struct X.
//
// The field is identified by its index within the field list of the
// struct type of X; by using numeric indices we avoid ambiguity of
// package-local identifiers and permit compact representations.
//
// Pos() returns the position of the ast.SelectorExpr.Sel for the
// field, if explicit in the source. For implicit selections, returns
// the position of the inducing explicit selection.

// Example printed form:
//
//	t1 = t0.name [#1]
type Field struct {
	register
	X     Value // struct
	Field int   // index into CoreType(X.Type()).(*types.Struct).Fields
}

// The IndexAddr instruction yields the address of the element at
// index Index of collection X.  Index is an integer expression.
//
// The elements of maps and strings are not addressable; use Lookup (map),
// Index (string), or MapUpdate instead.
//
// Dynamically, this instruction panics if X evaluates to a nil *array
// pointer.
//
// Type() returns a (possibly named) *types.Pointer.
//
// Pos() returns the ast.IndexExpr.Lbrack for the index operation, if
// explicit in the source.
//
// Example printed form:
//
//	t2 = &t0[t1]
type IndexAddr struct {
	register
	X     Value // *array, slice or type parameter with types array, *array, or slice.
	Index Value // numeric index
}

// The Index instruction yields element Index of collection X, an array,
// string or type parameter containing an array, a string, a pointer to an,
// array or a slice.
//
// Pos() returns the ast.IndexExpr.Lbrack for the index operation, if
// explicit in the source.
//
// Example printed form:
//
//	t2 = t0[t1]
type Index struct {
	register
	X     Value // array, string or type parameter with types array, *array, slice, or string.
	Index Value // integer index
}

// The Lookup instruction yields element Index of collection map X.
// Index is the appropriate key type.
//
// If CommaOk, the result is a 2-tuple of the value above and a
// boolean indicating the result of a map membership test for the key.
// The components of the tuple are accessed using Extract.
//
// Pos() returns the ast.IndexExpr.Lbrack, if explicit in the source.
//
// Example printed form:
//
//	t2 = t0[t1]
//	t5 = t3[t4],ok
type Lookup struct {
	register
	X       Value // map
	Index   Value // key-typed index
	CommaOk bool  // return a value,ok pair
}

// SelectState is a helper for Select.
// It represents one goal state and its corresponding communication.
type SelectState struct {
	Dir       types.ChanDir // direction of case (SendOnly or RecvOnly)
	Chan      Value         // channel to use (for send or receive)
	Send      Value         // value to send (for send)
	Pos       token.Pos     // position of token.ARROW
	DebugNode ast.Node      // ast.SendStmt or ast.UnaryExpr(<-) [debug mode]
}

// The Select instruction tests whether (or blocks until) one
// of the specified sent or received states is entered.
//
// Let n be the number of States for which Dir==RECV and T_i (0<=i<n)
// be the element type of each such state's Chan.
// Select returns an n+2-tuple
//
//	(index int, recvOk bool, r_0 T_0, ... r_n-1 T_n-1)
//
// The tuple's components, described below, must be accessed via the
// Extract instruction.
//
// If Blocking, select waits until exactly one state holds, i.e. a
// channel becomes ready for the designated operation of sending or
// receiving; select chooses one among the ready states
// pseudorandomly, performs the send or receive operation, and sets
// 'index' to the index of the chosen channel.
//
// If !Blocking, select doesn't block if no states hold; instead it
// returns immediately with index equal to -1.
//
// If the chosen channel was used for a receive, the r_i component is
// set to the received value, where i is the index of that state among
// all n receive states; otherwise r_i has the zero value of type T_i.
// Note that the receive index i is not the same as the state
// index index.
//
// The second component of the triple, recvOk, is a boolean whose value
// is true iff the selected operation was a receive and the receive
// successfully yielded a value.
//
// Pos() returns the ast.SelectStmt.Select.
//
// Example printed form:
//
//	t3 = select nonblocking [<-t0, t1<-t2]
//	t4 = select blocking []
type Select struct {
	register
	States   []*SelectState
	Blocking bool
}

// The Range instruction yields an iterator over the domain and range
// of X, which must be a string or map.
//
// Elements are accessed via Next.
//
// Type() returns an opaque and degenerate "rangeIter" type.
//
// Pos() returns the ast.RangeStmt.For.
//
// Example printed form:
//
//	t0 = range "hello":string
type Range struct {
	register
	X Value // string or map
}

// The Next instruction reads and advances the (map or string)
// iterator Iter and returns a 3-tuple value (ok, k, v).  If the
// iterator is not exhausted, ok is true and k and v are the next
// elements of the domain and range, respectively.  Otherwise ok is
// false and k and v are undefined.
//
// Components of the tuple are accessed using Extract.
//
// The IsString field distinguishes iterators over strings from those
// over maps, as the Type() alone is insufficient: consider
// map[int]rune.
//
// Type() returns a *types.Tuple for the triple (ok, k, v).
// The types of k and/or v may be types.Invalid.
//
// Example printed form:
//
//	t1 = next t0
type Next struct {
	register
	Iter     Value
	IsString bool // true => string iterator; false => map iterator.
}

// The TypeAssert instruction tests whether interface value X has type
// AssertedType.
//
// If !CommaOk, on success it returns v, the result of the conversion
// (defined below); on failure it panics.
//
// If CommaOk: on success it returns a pair (v, true) where v is the
// result of the conversion; on failure it returns (z, false) where z
// is AssertedType's zero value.  The components of the pair must be
// accessed using the Extract instruction.
//
// If Underlying: tests whether interface value X has the underlying
// type AssertedType.
//
// If AssertedType is a concrete type, TypeAssert checks whether the
// dynamic type in interface X is equal to it, and if so, the result
// of the conversion is a copy of the value in the interface.
//
// If AssertedType is an interface, TypeAssert checks whether the
// dynamic type of the interface is assignable to it, and if so, the
// result of the conversion is a copy of the interface value X.
// If AssertedType is a superinterface of X.Type(), the operation will
// fail iff the operand is nil.  (Contrast with ChangeInterface, which
// performs no nil-check.)
//
// Type() reflects the actual type of the result, possibly a
// 2-types.Tuple; AssertedType is the asserted type.
//
// Depending on the TypeAssert's purpose, Pos may return:
//   - the ast.CallExpr.Lparen of an explicit T(e) conversion;
//   - the ast.TypeAssertExpr.Lparen of an explicit e.(T) operation;
//   - the ast.CaseClause.Case of a case of a type-switch statement;
//   - the Ident(m).NamePos of an interface method value i.m
//     (for which TypeAssert may be used to effect the nil check).
//
// Example printed form:
//
//	t1 = typeassert t0.(int)
//	t3 = typeassert,ok t2.(T)
type TypeAssert struct {
	register
	X            Value
	AssertedType types.Type
	CommaOk      bool
}

// The Extract instruction yields component Index of Tuple.
//
// This is used to access the results of instructions with multiple
// return values, such as Call, TypeAssert, Next, UnOp(ARROW) and
// IndexExpr(Map).
//
// Example printed form:
//
//	t1 = extract t0 #1
type Extract struct {
	register
	Tuple Value
	Index int
}

// Instructions executed for effect.  They do not yield a value. --------------------

// The Jump instruction transfers control to the sole successor of its
// owning block.
//
// A Jump must be the last instruction of its containing BasicBlock.
//
// Pos() returns NoPos.
//
// Example printed form:
//
//	jump done
type Jump struct {
	anInstruction
}

// The If instruction transfers control to one of the two successors
// of its owning block, depending on the boolean Cond: the first if
// true, the second if false.
//
// An If instruction must be the last instruction of its containing
// BasicBlock.
//
// Pos() returns NoPos.
//
// Example printed form:
//
//	if t0 goto done else body
type If struct {
	anInstruction
	Cond Value
}

// The Return instruction returns values and control back to the calling
// function.
//
// len(Results) is always equal to the number of results in the
// function's signature.
//
// If len(Results) > 1, Return returns a tuple value with the specified
// components which the caller must access using Extract instructions.
//
// There is no instruction to return a ready-made tuple like those
// returned by a "value,ok"-mode TypeAssert, Lookup or UnOp(ARROW) or
// a tail-call to a function with multiple result parameters.
//
// Return must be the last instruction of its containing BasicBlock.
// Such a block has no successors.
//
// Pos() returns the ast.ReturnStmt.Return, if explicit in the source.
//
// Example printed form:
//
//	return
//	return nil:I, 2:int
type Return struct {
	anInstruction
	Results []Value
	pos     token.Pos
}

// The RunDefers instruction pops and invokes the entire stack of
// procedure calls pushed by Defer instructions in this function.
//
// It is legal to encounter multiple 'rundefers' instructions in a
// single control-flow path through a function; this is useful in
// the combined init() function, for example.
//
// Pos() returns NoPos.
//
// Example printed form:
//
//	rundefers
type RunDefers struct {
	anInstruction
}

// The Panic instruction initiates a panic with value X.
//
// A Panic instruction must be the last instruction of its containing
// BasicBlock, which must have no successors.
//
// NB: 'go panic(x)' and 'defer panic(x)' do not use this instruction;
// they are treated as calls to a built-in function.
//
// Pos() returns the ast.CallExpr.Lparen if this panic was explicit
// in the source.
//
// Example printed form:
//
//	panic t0
type Panic struct {
	anInstruction
	X   Value // an interface{}
	pos token.Pos
}

// The Go instruction creates a new goroutine and calls the specified
// function within it.
//
// See CallCommon for generic function call documentation.
//
// Pos() returns the ast.GoStmt.Go.
//
// Example printed form:
//
//	go println(t0, t1)
//	go t3()
//	go invoke t5.Println(...t6)
type Go struct {
	anInstruction
	Call CallCommon
	pos  token.Pos
}

// The Defer instruction pushes the specified call onto a stack of
// functions to be called by a RunDefers instruction or by a panic.
//
// If DeferStack != nil, it indicates the defer list that the defer is
// added to. Defer list values come from the Builtin function
// ssa:deferstack. Calls to ssa:deferstack() produces the defer stack
// of the current function frame. DeferStack allows for deferring into an
// alternative function stack than the current function.
//
// See CallCommon for generic function call documentation.
//
// Pos() returns the ast.DeferStmt.Defer.
//
// Example printed form:
//
//	defer println(t0, t1)
//	defer t3()
//	defer invoke t5.Println(...t6)
type Defer struct {
	anInstruction
	Call       CallCommon
	DeferStack Value // stack of deferred functions (from ssa:deferstack() intrinsic) onto which this function is pushed
	pos        token.Pos
}

// The Send instruction sends X on channel Chan.
//
// Pos() returns the ast.SendStmt.Arrow, if explicit in the source.
//
// Example printed form:
//
//	send t0 <- t1
type Send struct {
	anInstruction
	Chan, X Value
	pos     token.Pos
}

// The Store instruction stores Val at address Addr.
// Stores can be of arbitrary types.
//
// Pos() returns the position of the source-level construct most closely
// associated with the memory store operation.
// Since implicit memory stores are numerous and varied and depend upon
// implementation choices, the details are not specified.
//
// Example printed form:
//
//	*x = y
type Store struct {
	anInstruction
	Addr Value
	Val  Value
	pos  token.Pos
}

// The MapUpdate instruction updates the association of Map[Key] to
// Value.
//
// Pos() returns the ast.KeyValueExpr.Colon or ast.IndexExpr.Lbrack,
// if explicit in the source.
//
// Example printed form:
//
//	t0[t1] = t2
type MapUpdate struct {
	anInstruction
	Map   Value
	Key   Value
	Value Value
	pos   token.Pos
}

// A DebugRef instruction maps a source-level expression Expr to the
// SSA value X that represents the value (!IsAddr) or address (IsAddr)
// of that expression.
//
// DebugRef is a pseudo-instruction: it has no dynamic effect.
//
// Pos() returns Expr.Pos(), the start position of the source-level
// expression.  This is not the same as the "designated" token as
// documented at Value.Pos(). e.g. CallExpr.Pos() does not return the
// position of the ("designated") Lparen token.
//
// If Expr is an *ast.Ident denoting a var or func, Object() returns
// the object; though this information can be obtained from the type
// checker, including it here greatly facilitates debugging.
// For non-Ident expressions, Object() returns nil.
//
// DebugRefs are generated only for functions built with debugging
// enabled; see Package.SetDebugMode() and the GlobalDebug builder
// mode flag.
//
// DebugRefs are not emitted for ast.Idents referring to constants or
// predeclared identifiers, since they are trivial and numerous.
// Nor are they emitted for ast.ParenExprs.
//
// (By representing these as instructions, rather than out-of-band,
// consistency is maintained during transformation passes by the
// ordinary SSA renaming machinery.)
//
// Example printed form:
//
//	; *ast.CallExpr @ 102:9 is t5
//	; var x float64 @ 109:72 is x
//	; address of *ast.CompositeLit @ 216:10 is t0
type DebugRef struct {
	// TODO(generics): Reconsider what DebugRefs are for generics.
	anInstruction
	Expr   ast.Expr     // the referring expression (never *ast.ParenExpr)
	object types.Object // the identity of the source var/func
	IsAddr bool         // Expr is addressable and X is the address it denotes
	X      Value        // the value or address of Expr
}

// Embeddable mix-ins and helpers for common parts of other structs. -----------

// register is a mix-in embedded by all SSA values that are also
// instructions, i.e. virtual registers, and provides a uniform
// implementation of most of the Value interface: Value.Name() is a
// numbered register (e.g. "t0"); the other methods are field accessors.
//
// Temporary names are automatically assigned to each register on
// completion of building a function in SSA form.
//
// Clients must not assume that the 'id' value (and the Name() derived
// from it) is unique within a function.  As always in this API,
// semantics are determined only by identity; names exist only to
// facilitate debugging.
type register struct {
	anInstruction
	num       int        // "name" of virtual register, e.g. "t0".  Not guaranteed unique.
	typ       types.Type // type of virtual register
	pos       token.Pos  // position of source expression, or NoPos
	referrers []Instruction
}

// anInstruction is a mix-in embedded by all Instructions.
// It provides the implementations of the Block and setBlock methods.
type anInstruction struct {
	block *BasicBlock // the basic block of this instruction
}

// CallCommon is contained by Go, Defer and Call to hold the
// common parts of a function or method call.
//
// Each CallCommon exists in one of two modes, function call and
// interface method invocation, or "call" and "invoke" for short.
//
// 1. "call" mode: when Method is nil (!IsInvoke), a CallCommon
// represents an ordinary function call of the value in Value,
// which may be a *Builtin, a *Function or any other value of kind
// 'func'.
//
// Value may be one of:
//
//	(a) a *Function, indicating a statically dispatched call
//	    to a package-level function, an anonymous function, or
//	    a method of a named type.
//	(b) a *MakeClosure, indicating an immediately applied
//	    function literal with free variables.
//	(c) a *Builtin, indicating a statically dispatched call
//	    to a built-in function.
//	(d) any other value, indicating a dynamically dispatched
//	    function call.
//
// StaticCallee returns the identity of the callee in cases
// (a) and (b), nil otherwise.
//
// Args contains the arguments to the call.  If Value is a method,
// Args[0] contains the receiver parameter.
//
// Example printed form:
//
//	t2 = println(t0, t1)
//	go t3()
//	defer t5(...t6)
//
// 2. "invoke" mode: when Method is non-nil (IsInvoke), a CallCommon
// represents a dynamically dispatched call to an interface method.
// In this mode, Value is the interface value and Method is the
// interface's abstract method. The interface value may be a type
// parameter. Note: an interface method may be shared by multiple
// interfaces due to embedding; Value.Type() provides the specific
// interface used for this call.
//
// Value is implicitly supplied to the concrete method implementation
// as the receiver parameter; in other words, Args[0] holds not the
// receiver but the first true argument.
//
// Example printed form:
//
//	t1 = invoke t0.String()
//	go invoke t3.Run(t2)
//	defer invoke t4.Handle(...t5)
//
// For all calls to variadic functions (Signature().Variadic()),
// the last element of Args is a slice.
type CallCommon struct {
	Value  Value       // receiver (invoke mode) or func value (call mode)
	Method *types.Func // interface method (invoke mode)
	Args   []Value     // actual parameters (in static method call, includes receiver)
	pos    token.Pos   // position of CallExpr.Lparen, iff explicit in source
}

// IsInvoke returns true if this call has "invoke" (not "call") mode.
func (c *CallCommon) IsInvoke() bool {
	return c.Method != nil
}

func (c *CallCommon) Pos() token.Pos { return c.pos }

// Signature returns the signature of the called function.
//
// For an "invoke"-mode call, the signature of the interface method is
// returned.
//
// In either "call" or "invoke" mode, if the callee is a method, its
// receiver is represented by sig.Recv, not sig.Params().At(0).
func (c *CallCommon) Signature() *types.Signature {
	if c.Method != nil {
		return c.Method.Type().(*types.Signature)
	}
	return typeparams.CoreType(c.Value.Type()).(*types.Signature)
}

// StaticCallee returns the callee if this is a trivially static
// "call"-mode call to a function.
func (c *CallCommon) StaticCallee() *Function {
	switch fn := c.Value.(type) {
	case *Function:
		return fn
	case *MakeClosure:
		return fn.Fn.(*Function)
	}
	return nil
}

// Description returns a description of the mode of this call suitable
// for a user interface, e.g., "static method call".
func (c *CallCommon) Description() string {
	switch fn := c.Value.(type) {
	case *Builtin:
		return "built-in function call"
	case *MakeClosure:
		return "static function closure call"
	case *Function:
		if fn.Signature.Recv() != nil {
			return "static method call"
		}
		return "static function call"
	}
	if c.IsInvoke() {
		return "dynamic method call" // ("invoke" mode)
	}
	return "dynamic function call"
}

// The CallInstruction interface, implemented by *Go, *Defer and *Call,
// exposes the common parts of function-calling instructions,
// yet provides a way back to the Value defined by *Call alone.
type CallInstruction interface {
	Instruction
	Common() *CallCommon // returns the common parts of the call
	Value() *Call        // returns the result value of the call (*Call) or nil (*Go, *Defer)
}

func (s *Call) Common() *CallCommon  { return &s.Call }
func (s *Defer) Common() *CallCommon { return &s.Call }
func (s *Go) Common() *CallCommon    { return &s.Call }

func (s *Call) Value() *Call  { return s }
func (s *Defer) Value() *Call { return nil }
func (s *Go) Value() *Call    { return nil }

func (v *Builtin) Type() types.Type        { return v.sig }
func (v *Builtin) Name() string            { return v.name }
func (*Builtin) Referrers() *[]Instruction { return nil }
func (v *Builtin) Pos() token.Pos          { return token.NoPos }
func (v *Builtin) Object() types.Object    { return types.Universe.Lookup(v.name) }
func (v *Builtin) Parent() *Function       { return nil }

func (v *FreeVar) Type() types.Type          { return v.typ }
func (v *FreeVar) Name() string              { return v.name }
func (v *FreeVar) Referrers() *[]Instruction { return &v.referrers }
func (v *FreeVar) Pos() token.Pos            { return v.pos }
func (v *FreeVar) Parent() *Function         { return v.parent }

func (v *Global) Type() types.Type                     { return v.typ }
func (v *Global) Name() string                         { return v.name }
func (v *Global) Parent() *Function                    { return nil }
func (v *Global) Pos() token.Pos                       { return v.pos }
func (v *Global) Referrers() *[]Instruction            { return nil }
func (v *Global) Token() token.Token                   { return token.VAR }
func (v *Global) Object() types.Object                 { return v.object }
func (v *Global) String() string                       { return v.RelString(nil) }
func (v *Global) Package() *Package                    { return v.Pkg }
func (v *Global) RelString(from *types.Package) string { return relString(v, from) }

func (v *Function) Name() string       { return v.name }
func (v *Function) Type() types.Type   { return v.Signature }
func (v *Function) Pos() token.Pos     { return v.pos }
func (v *Function) Token() token.Token { return token.FUNC }
func (v *Function) Object() types.Object {
	if v.object != nil {
		return types.Object(v.object)
	}
	return nil
}
func (v *Function) String() string    { return v.RelString(nil) }
func (v *Function) Package() *Package { return v.Pkg }
func (v *Function) Parent() *Function { return v.parent }
func (v *Function) Referrers() *[]Instruction {
	if v.parent != nil {
		return &v.referrers
	}
	return nil
}

// TypeParams are the function's type parameters if generic or the
// type parameters that were instantiated if fn is an instantiation.
func (fn *Function) TypeParams() *types.TypeParamList {
	return fn.typeparams
}

// TypeArgs are the types that TypeParams() were instantiated by to create fn
// from fn.Origin().
func (fn *Function) TypeArgs() []types.Type { return fn.typeargs }

// Origin returns the generic function from which fn was instantiated,
// or nil if fn is not an instantiation.
func (fn *Function) Origin() *Function {
	if fn.parent != nil && len(fn.typeargs) > 0 {
		// Nested functions are BUILT at a different time than their instances.
		// Build declared package if not yet BUILT. This is not an expected use
		// case, but is simple and robust.
		fn.declaredPackage().Build()
	}
	return origin(fn)
}

// origin is the function that fn is an instantiation of. Returns nil if fn is
// not an instantiation.
//
// Precondition: fn and the origin function are done building.
func origin(fn *Function) *Function {
	if fn.parent != nil && len(fn.typeargs) > 0 {
		return origin(fn.parent).AnonFuncs[fn.anonIdx]
	}
	return fn.topLevelOrigin
}

func (v *Parameter) Type() types.Type          { return v.typ }
func (v *Parameter) Name() string              { return v.name }
func (v *Parameter) Object() types.Object      { return v.object }
func (v *Parameter) Referrers() *[]Instruction { return &v.referrers }
func (v *Parameter) Pos() token.Pos            { return v.object.Pos() }
func (v *Parameter) Parent() *Function         { return v.parent }

func (v *Alloc) Type() types.Type          { return v.typ }
func (v *Alloc) Referrers() *[]Instruction { return &v.referrers }
func (v *Alloc) Pos() token.Pos            { return v.pos }

func (v *register) Type() types.Type          { return v.typ }
func (v *register) setType(typ types.Type)    { v.typ = typ }
func (v *register) Name() string              { return fmt.Sprintf("t%d", v.num) }
func (v *register) setNum(num int)            { v.num = num }
func (v *register) Referrers() *[]Instruction { return &v.referrers }
func (v *register) Pos() token.Pos            { return v.pos }
func (v *register) setPos(pos token.Pos)      { v.pos = pos }

func (v *anInstruction) Parent() *Function          { return v.block.parent }
func (v *anInstruction) Block() *BasicBlock         { return v.block }
func (v *anInstruction) setBlock(block *BasicBlock) { v.block = block }
func (v *anInstruction) Referrers() *[]Instruction  { return nil }

func (t *Type) Name() string                         { return t.object.Name() }
func (t *Type) Pos() token.Pos                       { return t.object.Pos() }
func (t *Type) Type() types.Type                     { return t.object.Type() }
func (t *Type) Token() token.Token                   { return token.TYPE }
func (t *Type) Object() types.Object                 { return t.object }
func (t *Type) String() string                       { return t.RelString(nil) }
func (t *Type) Package() *Package                    { return t.pkg }
func (t *Type) RelString(from *types.Package) string { return relString(t, from) }

func (c *NamedConst) Name() string                         { return c.object.Name() }
func (c *NamedConst) Pos() token.Pos                       { return c.object.Pos() }
func (c *NamedConst) String() string                       { return c.RelString(nil) }
func (c *NamedConst) Type() types.Type                     { return c.object.Type() }
func (c *NamedConst) Token() token.Token                   { return token.CONST }
func (c *NamedConst) Object() types.Object                 { return c.object }
func (c *NamedConst) Package() *Package                    { return c.pkg }
func (c *NamedConst) RelString(from *types.Package) string { return relString(c, from) }

func (d *DebugRef) Object() types.Object { return d.object }

// Func returns the package-level function of the specified name,
// or nil if not found.
func (p *Package) Func(name string) (f *Function) {
	f, _ = p.Members[name].(*Function)
	return
}

// Var returns the package-level variable of the specified name,
// or nil if not found.
func (p *Package) Var(name string) (g *Global) {
	g, _ = p.Members[name].(*Global)
	return
}

// Const returns the package-level constant of the specified name,
// or nil if not found.
func (p *Package) Const(name string) (c *NamedConst) {
	c, _ = p.Members[name].(*NamedConst)
	return
}

// Type returns the package-level type of the specified name,
// or nil if not found.
func (p *Package) Type(name string) (t *Type) {
	t, _ = p.Members[name].(*Type)
	return
}

func (v *Call) Pos() token.Pos      { return v.Call.pos }
func (s *Defer) Pos() token.Pos     { return s.pos }
func (s *Go) Pos() token.Pos        { return s.pos }
func (s *MapUpdate) Pos() token.Pos { return s.pos }
func (s *Panic) Pos() token.Pos     { return s.pos }
func (s *Return) Pos() token.Pos    { return s.pos }
func (s *Send) Pos() token.Pos      { return s.pos }
func (s *Store) Pos() token.Pos     { return s.pos }
func (s *If) Pos() token.Pos        { return token.NoPos }
func (s *Jump) Pos() token.Pos      { return token.NoPos }
func (s *RunDefers) Pos() token.Pos { return token.NoPos }
func (s *DebugRef) Pos() token.Pos  { return s.Expr.Pos() }

// Operands.

func (v *Alloc) Operands(rands []*Value) []*Value {
	return rands
}

func (v *BinOp) Operands(rands []*Value) []*Value {
	return append(rands, &v.X, &v.Y)
}

func (c *CallCommon) Operands(rands []*Value) []*Value {
	rands = append(rands, &c.Value)
	for i := range c.Args {
		rands = append(rands, &c.Args[i])
	}
	return rands
}

func (s *Go) Operands(rands []*Value) []*Value {
	return s.Call.Operands(rands)
}

func (s *Call) Operands(rands []*Value) []*Value {
	return s.Call.Operands(rands)
}

func (s *Defer) Operands(rands []*Value) []*Value {
	return append(s.Call.Operands(rands), &s.DeferStack)
}

func (v *ChangeInterface) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *ChangeType) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *Convert) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *MultiConvert) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *SliceToArrayPointer) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (s *DebugRef) Operands(rands []*Value) []*Value {
	return append(rands, &s.X)
}

func (v *Extract) Operands(rands []*Value) []*Value {
	return append(rands, &v.Tuple)
}

func (v *Field) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *FieldAddr) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (s *If) Operands(rands []*Value) []*Value {
	return append(rands, &s.Cond)
}

func (v *Index) Operands(rands []*Value) []*Value {
	return append(rands, &v.X, &v.Index)
}

func (v *IndexAddr) Operands(rands []*Value) []*Value {
	return append(rands, &v.X, &v.Index)
}

func (*Jump) Operands(rands []*Value) []*Value {
	return rands
}

func (v *Lookup) Operands(rands []*Value) []*Value {
	return append(rands, &v.X, &v.Index)
}

func (v *MakeChan) Operands(rands []*Value) []*Value {
	return append(rands, &v.Size)
}

func (v *MakeClosure) Operands(rands []*Value) []*Value {
	rands = append(rands, &v.Fn)
	for i := range v.Bindings {
		rands = append(rands, &v.Bindings[i])
	}
	return rands
}

func (v *MakeInterface) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *MakeMap) Operands(rands []*Value) []*Value {
	return append(rands, &v.Reserve)
}

func (v *MakeSlice) Operands(rands []*Value) []*Value {
	return append(rands, &v.Len, &v.Cap)
}

func (v *MapUpdate) Operands(rands []*Value) []*Value {
	return append(rands, &v.Map, &v.Key, &v.Value)
}

func (v *Next) Operands(rands []*Value) []*Value {
	return append(rands, &v.Iter)
}

func (s *Panic) Operands(rands []*Value) []*Value {
	return append(rands, &s.X)
}

func (v *Phi) Operands(rands []*Value) []*Value {
	for i := range v.Edges {
		rands = append(rands, &v.Edges[i])
	}
	return rands
}

func (v *Range) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (s *Return) Operands(rands []*Value) []*Value {
	for i := range s.Results {
		rands = append(rands, &s.Results[i])
	}
	return rands
}

func (*RunDefers) Operands(rands []*Value) []*Value {
	return rands
}

func (v *Select) Operands(rands []*Value) []*Value {
	for i := range v.States {
		rands = append(rands, &v.States[i].Chan, &v.States[i].Send)
	}
	return rands
}

func (s *Send) Operands(rands []*Value) []*Value {
	return append(rands, &s.Chan, &s.X)
}

func (v *Slice) Operands(rands []*Value) []*Value {
	return append(rands, &v.X, &v.Low, &v.High, &v.Max)
}

func (s *Store) Operands(rands []*Value) []*Value {
	return append(rands, &s.Addr, &s.Val)
}

func (v *TypeAssert) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

func (v *UnOp) Operands(rands []*Value) []*Value {
	return append(rands, &v.X)
}

// Non-Instruction Values:
func (v *Builtin) Operands(rands []*Value) []*Value   { return rands }
func (v *FreeVar) Operands(rands []*Value) []*Value   { return rands }
func (v *Const) Operands(rands []*Value) []*Value     { return rands }
func (v *Function) Operands(rands []*Value) []*Value  { return rands }
func (v *Global) Operands(rands []*Value) []*Value    { return rands }
func (v *Parameter) Operands(rands []*Value) []*Value { return rands }


================================================
FILE: go/ssa/ssautil/deprecated.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil

// This file contains deprecated public APIs.
// We discourage their use.

import (
	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/ssa"
)

// CreateProgram returns a new program in SSA form, given a program
// loaded from source.  An SSA package is created for each transitively
// error-free package of lprog.
//
// Code for bodies of functions is not built until Build is called
// on the result.
//
// The mode parameter controls diagnostics and checking during SSA construction.
//
// Deprecated: Use [golang.org/x/tools/go/packages] and the [Packages]
// function instead; see ssa.Example_loadPackages.
func CreateProgram(lprog *loader.Program, mode ssa.BuilderMode) *ssa.Program {
	prog := ssa.NewProgram(lprog.Fset, mode)

	for _, info := range lprog.AllPackages {
		if info.TransitivelyErrorFree {
			prog.CreatePackage(info.Pkg, info.Files, &info.Info, info.Importable)
		}
	}

	return prog
}


================================================
FILE: go/ssa/ssautil/deprecated_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil_test

// Tests of deprecated public APIs.
// We are keeping some tests around to have some test of the public API.

import (
	"go/parser"
	"os"
	"testing"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
)

// TestCreateProgram tests CreateProgram which has an x/tools/go/loader.Program.
func TestCreateProgram(t *testing.T) {
	testenv.NeedsGoBuild(t) // for importer.Default()

	conf := loader.Config{ParserMode: parser.ParseComments}
	f, err := conf.ParseFile("hello.go", hello)
	if err != nil {
		t.Fatal(err)
	}

	conf.CreateFromFiles("main", f)
	iprog, err := conf.Load()
	if err != nil {
		t.Fatal(err)
	}
	if len(iprog.Created) != 1 {
		t.Fatalf("Expected 1 Created package. got %d", len(iprog.Created))
	}
	pkg := iprog.Created[0].Pkg

	prog := ssautil.CreateProgram(iprog, ssa.BuilderMode(0))
	ssapkg := prog.Package(pkg)
	ssapkg.Build()

	if pkg.Name() != "main" {
		t.Errorf("pkg.Name() = %s, want main", pkg.Name())
	}
	if ssapkg.Func("main") == nil {
		ssapkg.WriteTo(os.Stderr)
		t.Errorf("ssapkg has no main function")
	}
}


================================================
FILE: go/ssa/ssautil/load.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil

// This file defines utility functions for constructing programs in SSA form.

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
)

// Packages creates an SSA program for a set of packages.
//
// The packages must have been loaded from source syntax using the
// [packages.Load] function in [packages.LoadSyntax] or
// [packages.LoadAllSyntax] mode.
//
// Packages creates an SSA package for each well-typed package in the
// initial list, plus all their dependencies. The resulting list of
// packages corresponds to the list of initial packages, and may contain
// a nil if SSA code could not be constructed for the corresponding initial
// package due to type errors.
//
// Code for bodies of functions is not built until [Program.Build] is
// called on the resulting Program. SSA code is constructed only for
// the initial packages with well-typed syntax trees.
//
// The mode parameter controls diagnostics and checking during SSA construction.
func Packages(initial []*packages.Package, mode ssa.BuilderMode) (*ssa.Program, []*ssa.Package) {
	// TODO(adonovan): opt: this calls CreatePackage far more than
	// necessary: for all dependencies, not just the (non-initial)
	// direct dependencies of the initial packages.
	//
	// But can it reasonably be changed without breaking the
	// spirit and/or letter of the law above? Clients may notice
	// if we call CreatePackage less, as methods like
	// Program.FuncValue will return nil. Or must we provide a new
	// function (and perhaps deprecate this one)? Is it worth it?
	//
	// Tim King makes the interesting point that it would be
	// possible to entirely alleviate the client from the burden
	// of calling CreatePackage for non-syntax packages, if we
	// were to treat vars and funcs lazily in the same way we now
	// treat methods. (In essence, try to move away from the
	// notion of ssa.Packages, and make the Program answer
	// all reasonable questions about any types.Object.)

	return doPackages(initial, mode, false)
}

// AllPackages creates an SSA program for a set of packages plus all
// their dependencies.
//
// The packages must have been loaded from source syntax using the
// [packages.Load] function in [packages.LoadAllSyntax] mode.
//
// AllPackages creates an SSA package for each well-typed package in the
// initial list, plus all their dependencies. The resulting list of
// packages corresponds to the list of initial packages, and may contain
// a nil if SSA code could not be constructed for the corresponding
// initial package due to type errors.
//
// Code for bodies of functions is not built until Build is called on
// the resulting Program. SSA code is constructed for all packages with
// well-typed syntax trees.
//
// The mode parameter controls diagnostics and checking during SSA construction.
func AllPackages(initial []*packages.Package, mode ssa.BuilderMode) (*ssa.Program, []*ssa.Package) {
	return doPackages(initial, mode, true)
}

func doPackages(initial []*packages.Package, mode ssa.BuilderMode, deps bool) (*ssa.Program, []*ssa.Package) {

	var fset *token.FileSet
	if len(initial) > 0 {
		fset = initial[0].Fset
	}

	prog := ssa.NewProgram(fset, mode)

	isInitial := make(map[*packages.Package]bool, len(initial))
	for _, p := range initial {
		isInitial[p] = true
	}

	ssamap := make(map[*packages.Package]*ssa.Package)
	packages.Visit(initial, nil, func(p *packages.Package) {
		if p.Types != nil && !p.IllTyped {
			var files []*ast.File
			var info *types.Info
			if deps || isInitial[p] {
				files = p.Syntax
				info = p.TypesInfo
			}
			ssamap[p] = prog.CreatePackage(p.Types, files, info, true)
		}
	})

	var ssapkgs []*ssa.Package
	for _, p := range initial {
		ssapkgs = append(ssapkgs, ssamap[p]) // may be nil
	}
	return prog, ssapkgs
}

// BuildPackage builds an SSA program with SSA intermediate
// representation (IR) for all functions of a single package.
//
// It populates pkg by type-checking the specified file syntax trees.  All
// dependencies are loaded using the importer specified by tc, which
// typically loads compiler export data; SSA code cannot be built for
// those packages.  BuildPackage then constructs an [ssa.Program] with all
// dependency packages created, and builds and returns the SSA package
// corresponding to pkg.
//
// The caller must have set pkg.Path to the import path.
//
// The operation fails if there were any type-checking or import errors.
//
// See ../example_test.go for an example.
func BuildPackage(tc *types.Config, fset *token.FileSet, pkg *types.Package, files []*ast.File, mode ssa.BuilderMode) (*ssa.Package, *types.Info, error) {
	if fset == nil {
		panic("no token.FileSet")
	}
	if pkg.Path() == "" {
		panic("package has no import path")
	}

	info := &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Instances:    make(map[*ast.Ident]types.Instance),
		Scopes:       make(map[ast.Node]*types.Scope),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		FileVersions: make(map[*ast.File]string),
	}
	if err := types.NewChecker(tc, fset, pkg, info).Files(files); err != nil {
		return nil, nil, err
	}

	prog := ssa.NewProgram(fset, mode)

	// Create SSA packages for all imports.
	// Order is not significant.
	created := make(map[*types.Package]bool)
	var createAll func(pkgs []*types.Package)
	createAll = func(pkgs []*types.Package) {
		for _, p := range pkgs {
			if !created[p] {
				created[p] = true
				prog.CreatePackage(p, nil, nil, true)
				createAll(p.Imports())
			}
		}
	}
	createAll(pkg.Imports())

	// TODO(adonovan): we could replace createAll with just:
	//
	// // Create SSA packages for all imports.
	// for _, p := range pkg.Imports() {
	// 	prog.CreatePackage(p, nil, nil, true)
	// }
	//
	// (with minor changes to changes to ../builder_test.go as
	// shown in CL 511715 PS 10.) But this would strictly violate
	// the letter of the doc comment above, which says "all
	// dependencies created".
	//
	// Tim makes the good point with some extra work we could
	// remove the need for any CreatePackage calls except the
	// ones with syntax (i.e. primary packages). Of course
	// You wouldn't have ssa.Packages and Members for as
	// many things but no-one really uses that anyway.
	// I wish I had done this from the outset.

	// Create and build the primary package.
	ssapkg := prog.CreatePackage(pkg, files, info, false)
	ssapkg.Build()
	return ssapkg, info, nil
}


================================================
FILE: go/ssa/ssautil/load_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil_test

import (
	"bytes"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"path"
	"strings"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/packagestest"
	"golang.org/x/tools/internal/testenv"
)

const hello = `package main

import "fmt"

func main() {
	fmt.Println("Hello, world")
}
`

func TestBuildPackage(t *testing.T) {
	testenv.NeedsGoBuild(t) // for importer.Default()

	// There is a more substantial test of BuildPackage and the
	// SSA program it builds in ../ssa/builder_test.go.

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", hello, 0)
	if err != nil {
		t.Fatal(err)
	}

	for _, mode := range []ssa.BuilderMode{
		ssa.SanityCheckFunctions,
		ssa.InstantiateGenerics | ssa.SanityCheckFunctions,
	} {
		pkg := types.NewPackage("hello", "")
		ssapkg, _, err := ssautil.BuildPackage(&types.Config{Importer: importer.Default()}, fset, pkg, []*ast.File{f}, mode)
		if err != nil {
			t.Fatal(err)
		}
		if pkg.Name() != "main" {
			t.Errorf("pkg.Name() = %s, want main", pkg.Name())
		}
		if ssapkg.Func("main") == nil {
			ssapkg.WriteTo(os.Stderr)
			t.Errorf("ssapkg has no main function")
		}

	}
}

func TestPackages(t *testing.T) {
	testenv.NeedsGoPackages(t)

	cfg := &packages.Config{Mode: packages.LoadSyntax}
	initial, err := packages.Load(cfg, "bytes")
	if err != nil {
		t.Fatal(err)
	}
	if packages.PrintErrors(initial) > 0 {
		t.Fatal("there were errors")
	}

	for _, mode := range []ssa.BuilderMode{
		ssa.SanityCheckFunctions,
		ssa.SanityCheckFunctions | ssa.InstantiateGenerics,
	} {
		prog, pkgs := ssautil.Packages(initial, mode)
		bytesNewBuffer := pkgs[0].Func("NewBuffer")
		bytesNewBuffer.Pkg.Build()

		// We'll dump the SSA of bytes.NewBuffer because it is small and stable.
		out := new(bytes.Buffer)
		bytesNewBuffer.WriteTo(out)

		// For determinism, sanitize the location.
		location := prog.Fset.Position(bytesNewBuffer.Pos()).String()
		got := strings.Replace(out.String(), location, "$GOROOT/src/bytes/buffer.go:1", -1)

		want := `
# Name: bytes.NewBuffer
# Package: bytes
# Location: $GOROOT/src/bytes/buffer.go:1
func NewBuffer(buf []byte) *Buffer:
0:                                                                entry P:0 S:0
	t0 = new Buffer (complit)                                       *Buffer
	t1 = &t0.buf [#0]                                               *[]byte
	*t1 = buf
	return t0

`[1:]
		if got != want {
			t.Errorf("bytes.NewBuffer SSA = <<%s>>, want <<%s>>", got, want)
		}
	}
}

func TestBuildPackage_MissingImport(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "bad.go", `package bad; import "missing"`, 0)
	if err != nil {
		t.Fatal(err)
	}

	pkg := types.NewPackage("bad", "")
	ssapkg, _, err := ssautil.BuildPackage(new(types.Config), fset, pkg, []*ast.File{f}, ssa.BuilderMode(0))
	if err == nil || ssapkg != nil {
		t.Fatal("BuildPackage succeeded unexpectedly")
	}
}

func TestIssue28106(t *testing.T) {
	testenv.NeedsGoPackages(t)

	// In go1.10, go/packages loads all packages from source, not
	// export data, but does not type check function bodies of
	// imported packages. This test ensures that we do not attempt
	// to run the SSA builder on functions without type information.
	cfg := &packages.Config{Mode: packages.LoadSyntax}
	pkgs, err := packages.Load(cfg, "runtime")
	if err != nil {
		t.Fatal(err)
	}
	prog, _ := ssautil.Packages(pkgs, ssa.BuilderMode(0))
	prog.Build() // no crash
}

func TestIssue53604(t *testing.T) {
	// Tests that variable initializers are not added to init() when syntax
	// is not present but types.Info is available.
	//
	// Packages x, y, z are loaded with mode `packages.LoadSyntax`.
	// Package x imports y, and y imports z.
	// Packages are built using ssautil.Packages() with x and z as roots.
	// This setup creates y using CreatePackage(pkg, files, info, ...)
	// where len(files) == 0 but info != nil.
	//
	// Tests that globals from y are not initialized.
	e := packagestest.Export(t, packagestest.Modules, []packagestest.Module{
		{
			Name: "golang.org/fake",
			Files: map[string]any{
				"x/x.go": `package x; import "golang.org/fake/y"; var V = y.F()`,
				"y/y.go": `package y; import "golang.org/fake/z"; var F = func () *int { return &z.Z } `,
				"z/z.go": `package z; var Z int`,
			},
		},
	})
	defer e.Cleanup()

	// Load x and z as entry packages using packages.LoadSyntax
	e.Config.Mode = packages.LoadSyntax
	pkgs, err := packages.Load(e.Config, path.Join(e.Temp(), "fake/x"), path.Join(e.Temp(), "fake/z"))
	if err != nil {
		t.Fatal(err)
	}
	for _, p := range pkgs {
		if len(p.Errors) > 0 {
			t.Fatalf("%v", p.Errors)
		}
	}

	prog, _ := ssautil.Packages(pkgs, ssa.BuilderMode(0))
	prog.Build()

	// y does not initialize F.
	y := prog.ImportedPackage("golang.org/fake/y")
	if y == nil {
		t.Fatal("Failed to load intermediate package y")
	}
	yinit := y.Members["init"].(*ssa.Function)
	for _, bb := range yinit.Blocks {
		for _, i := range bb.Instrs {
			if store, ok := i.(*ssa.Store); ok && store.Addr == y.Var("F") {
				t.Errorf("y.init() stores to F %v", store)
			}
		}
	}

}


================================================
FILE: go/ssa/ssautil/switch.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil

// This file implements discovery of switch and type-switch constructs
// from low-level control flow.
//
// Many techniques exist for compiling a high-level switch with
// constant cases to efficient machine code.  The optimal choice will
// depend on the data type, the specific case values, the code in the
// body of each case, and the hardware.
// Some examples:
// - a lookup table (for a switch that maps constants to constants)
// - a computed goto
// - a binary tree
// - a perfect hash
// - a two-level switch (to partition constant strings by their first byte).

import (
	"bytes"
	"fmt"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/ssa"
)

// A ConstCase represents a single constant comparison.
// It is part of a Switch.
type ConstCase struct {
	Block *ssa.BasicBlock // block performing the comparison
	Body  *ssa.BasicBlock // body of the case
	Value *ssa.Const      // case comparand
}

// A TypeCase represents a single type assertion.
// It is part of a Switch.
type TypeCase struct {
	Block   *ssa.BasicBlock // block performing the type assert
	Body    *ssa.BasicBlock // body of the case
	Type    types.Type      // case type
	Binding ssa.Value       // value bound by this case
}

// A Switch is a logical high-level control flow operation
// (a multiway branch) discovered by analysis of a CFG containing
// only if/else chains.  It is not part of the ssa.Instruction set.
//
// One of ConstCases and TypeCases has length >= 2;
// the other is nil.
//
// In a value switch, the list of cases may contain duplicate constants.
// A type switch may contain duplicate types, or types assignable
// to an interface type also in the list.
// TODO(adonovan): eliminate such duplicates.
type Switch struct {
	Start      *ssa.BasicBlock // block containing start of if/else chain
	X          ssa.Value       // the switch operand
	ConstCases []ConstCase     // ordered list of constant comparisons
	TypeCases  []TypeCase      // ordered list of type assertions
	Default    *ssa.BasicBlock // successor if all comparisons fail
}

func (sw *Switch) String() string {
	// We represent each block by the String() of its
	// first Instruction, e.g. "print(42:int)".
	var buf bytes.Buffer
	if sw.ConstCases != nil {
		fmt.Fprintf(&buf, "switch %s {\n", sw.X.Name())
		for _, c := range sw.ConstCases {
			fmt.Fprintf(&buf, "case %s: %s\n", c.Value, c.Body.Instrs[0])
		}
	} else {
		fmt.Fprintf(&buf, "switch %s.(type) {\n", sw.X.Name())
		for _, c := range sw.TypeCases {
			fmt.Fprintf(&buf, "case %s %s: %s\n",
				c.Binding.Name(), c.Type, c.Body.Instrs[0])
		}
	}
	if sw.Default != nil {
		fmt.Fprintf(&buf, "default: %s\n", sw.Default.Instrs[0])
	}
	fmt.Fprintf(&buf, "}")
	return buf.String()
}

// Switches examines the control-flow graph of fn and returns the
// set of inferred value and type switches.  A value switch tests an
// ssa.Value for equality against two or more compile-time constant
// values.  Switches involving link-time constants (addresses) are
// ignored.  A type switch type-asserts an ssa.Value against two or
// more types.
//
// The switches are returned in dominance order.
//
// The resulting switches do not necessarily correspond to uses of the
// 'switch' keyword in the source: for example, a single source-level
// switch statement with non-constant cases may result in zero, one or
// many Switches, one per plural sequence of constant cases.
// Switches may even be inferred from if/else- or goto-based control flow.
// (In general, the control flow constructs of the source program
// cannot be faithfully reproduced from the SSA representation.)
func Switches(fn *ssa.Function) []Switch {
	// Traverse the CFG in dominance order, so we don't
	// enter an if/else-chain in the middle.
	var switches []Switch
	seen := make(map[*ssa.BasicBlock]bool) // TODO(adonovan): opt: use ssa.blockSet
	for _, b := range fn.DomPreorder() {
		if x, k := isComparisonBlock(b); x != nil {
			// Block b starts a switch.
			sw := Switch{Start: b, X: x}
			valueSwitch(&sw, k, seen)
			if len(sw.ConstCases) > 1 {
				switches = append(switches, sw)
			}
		}

		if y, x, T := isTypeAssertBlock(b); y != nil {
			// Block b starts a type switch.
			sw := Switch{Start: b, X: x}
			typeSwitch(&sw, y, T, seen)
			if len(sw.TypeCases) > 1 {
				switches = append(switches, sw)
			}
		}
	}
	return switches
}

func valueSwitch(sw *Switch, k *ssa.Const, seen map[*ssa.BasicBlock]bool) {
	b := sw.Start
	x := sw.X
	for x == sw.X {
		if seen[b] {
			break
		}
		seen[b] = true

		sw.ConstCases = append(sw.ConstCases, ConstCase{
			Block: b,
			Body:  b.Succs[0],
			Value: k,
		})
		b = b.Succs[1]
		if len(b.Instrs) > 2 {
			// Block b contains not just 'if x == k',
			// so it may have side effects that
			// make it unsafe to elide.
			break
		}
		if len(b.Preds) != 1 {
			// Block b has multiple predecessors,
			// so it cannot be treated as a case.
			break
		}
		x, k = isComparisonBlock(b)
	}
	sw.Default = b
}

func typeSwitch(sw *Switch, y ssa.Value, T types.Type, seen map[*ssa.BasicBlock]bool) {
	b := sw.Start
	x := sw.X
	for x == sw.X {
		if seen[b] {
			break
		}
		seen[b] = true

		sw.TypeCases = append(sw.TypeCases, TypeCase{
			Block:   b,
			Body:    b.Succs[0],
			Type:    T,
			Binding: y,
		})
		b = b.Succs[1]
		if len(b.Instrs) > 4 {
			// Block b contains not just
			//  {TypeAssert; Extract #0; Extract #1; If}
			// so it may have side effects that
			// make it unsafe to elide.
			break
		}
		if len(b.Preds) != 1 {
			// Block b has multiple predecessors,
			// so it cannot be treated as a case.
			break
		}
		y, x, T = isTypeAssertBlock(b)
	}
	sw.Default = b
}

// isComparisonBlock returns the operands (v, k) if a block ends with
// a comparison v==k, where k is a compile-time constant.
func isComparisonBlock(b *ssa.BasicBlock) (v ssa.Value, k *ssa.Const) {
	if n := len(b.Instrs); n >= 2 {
		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
			if binop, ok := i.Cond.(*ssa.BinOp); ok && binop.Block() == b && binop.Op == token.EQL {
				if k, ok := binop.Y.(*ssa.Const); ok {
					return binop.X, k
				}
				if k, ok := binop.X.(*ssa.Const); ok {
					return binop.Y, k
				}
			}
		}
	}
	return
}

// isTypeAssertBlock returns the operands (y, x, T) if a block ends with
// a type assertion "if y, ok := x.(T); ok {".
func isTypeAssertBlock(b *ssa.BasicBlock) (y, x ssa.Value, T types.Type) {
	if n := len(b.Instrs); n >= 4 {
		if i, ok := b.Instrs[n-1].(*ssa.If); ok {
			if ext1, ok := i.Cond.(*ssa.Extract); ok && ext1.Block() == b && ext1.Index == 1 {
				if ta, ok := ext1.Tuple.(*ssa.TypeAssert); ok && ta.Block() == b {
					// hack: relies upon instruction ordering.
					if ext0, ok := b.Instrs[n-3].(*ssa.Extract); ok {
						return ext0, ta.X, ta.AssertedType
					}
				}
			}
		}
	}
	return
}


================================================
FILE: go/ssa/ssautil/switch_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package ssautil_test

import (
	"strings"
	"testing"

	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestSwitches(t *testing.T) {
	archive, err := txtar.ParseFile("testdata/switches.txtar")
	if err != nil {
		t.Fatal(err)
	}
	ppkgs := testfiles.LoadPackages(t, archive, ".")
	if len(ppkgs) != 1 {
		t.Fatalf("Expected to load one package but got %d", len(ppkgs))
	}
	f := ppkgs[0].Syntax[0]

	prog, _ := ssautil.Packages(ppkgs, ssa.BuilderMode(0))
	mainPkg := prog.Package(ppkgs[0].Types)
	mainPkg.Build()

	for _, mem := range mainPkg.Members {
		if fn, ok := mem.(*ssa.Function); ok {
			if fn.Synthetic != "" {
				continue // e.g. init()
			}
			// Each (multi-line) "switch" comment within
			// this function must match the printed form
			// of a ConstSwitch.
			var wantSwitches []string
			for _, c := range f.Comments {
				if fn.Syntax().Pos() <= c.Pos() && c.Pos() < fn.Syntax().End() {
					text := strings.TrimSpace(c.Text())
					if strings.HasPrefix(text, "switch ") {
						wantSwitches = append(wantSwitches, text)
					}
				}
			}

			switches := ssautil.Switches(fn)
			if len(switches) != len(wantSwitches) {
				t.Errorf("in %s, found %d switches, want %d", fn, len(switches), len(wantSwitches))
			}
			for i, sw := range switches {
				got := sw.String()
				if i >= len(wantSwitches) {
					continue
				}
				want := wantSwitches[i]
				if got != want {
					t.Errorf("in %s, found switch %d: got <<%s>>, want <<%s>>", fn, i, got, want)
				}
			}
		}
	}
}


================================================
FILE: go/ssa/ssautil/testdata/switches.txtar
================================================
-- go.mod --
module example.com
go 1.22

-- switches.go --
package main

// This file is the input to TestSwitches in switch_test.go.
// Each multiway conditional with constant or type cases (Switch)
// discovered by Switches is printed, and compared with the
// comments.
//
// The body of each case is printed as the value of its first
// instruction.

// -------- Value switches --------

func SimpleSwitch(x, y int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(23:int)
	// case 3:int: print(23:int)
	// case 4:int: print(3:int)
	// default: x == y
	// }
	switch x {
	case 1:
		print(1)
	case 2, 3:
		print(23)
		fallthrough
	case 4:
		print(3)
	default:
		print(4)
	case y:
		print(5)
	}
	print(6)
}

func four() int { return 4 }

// A non-constant case makes a switch "impure", but its pure
// cases form two separate switches.
func SwitchWithNonConstantCase(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(23:int)
	// case 3:int: print(23:int)
	// default: four()
	// }

	// switch x {
	// case 5:int: print(5:int)
	// case 6:int: print(6:int)
	// default: print("done":string)
	// }
	switch x {
	case 1:
		print(1)
	case 2, 3:
		print(23)
	case four():
		print(3)
	case 5:
		print(5)
	case 6:
		print(6)
	}
	print("done")
}

// Switches may be found even where the source
// program doesn't have a switch statement.

func ImplicitSwitches(x, y int) {
	// switch x {
	// case 1:int: print(12:int)
	// case 2:int: print(12:int)
	// default: x < 5:int
	// }
	if x == 1 || 2 == x || x < 5 {
		print(12)
	}

	// switch x {
	// case 3:int: print(34:int)
	// case 4:int: print(34:int)
	// default: x == y
	// }
	if x == 3 || 4 == x || x == y {
		print(34)
	}

	// Not a switch: no consistent variable.
	if x == 5 || y == 6 {
		print(56)
	}

	// Not a switch: only one constant comparison.
	if x == 7 || x == y {
		print(78)
	}
}

func IfElseBasedSwitch(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(2:int)
	// default: print("else":string)
	// }
	if x == 1 {
		print(1)
	} else if x == 2 {
		print(2)
	} else {
		print("else")
	}
}

func GotoBasedSwitch(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(2:int)
	// default: print("else":string)
	// }
	if x == 1 {
		goto L1
	}
	if x == 2 {
		goto L2
	}
	print("else")
L1:
	print(1)
	goto end
L2:
	print(2)
end:
}

func SwitchInAForLoop(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(2:int)
	// default: print("head":string)
	// }
loop:
	for {
		print("head")
		switch x {
		case 1:
			print(1)
			break loop
		case 2:
			print(2)
			break loop
		}
	}
}

// This case is a switch in a for-loop, both constructed using goto.
// As before, the default case points back to the block containing the
// switch, but that's ok.
func SwitchInAForLoopUsingGoto(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: print(2:int)
	// default: print("head":string)
	// }
loop:
	print("head")
	if x == 1 {
		goto L1
	}
	if x == 2 {
		goto L2
	}
	goto loop
L1:
	print(1)
	goto end
L2:
	print(2)
end:
}

func UnstructuredSwitchInAForLoop(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 2:int: x == 1:int
	// default: print("end":string)
	// }
	for {
		if x == 1 {
			print(1)
			return
		}
		if x == 2 {
			continue
		}
		break
	}
	print("end")
}

func CaseWithMultiplePreds(x int) {
	for {
		if x == 1 {
			print(1)
			return
		}
	loop:
		// This block has multiple predecessors,
		// so can't be treated as a switch case.
		if x == 2 {
			goto loop
		}
		break
	}
	print("end")
}

func DuplicateConstantsAreNotEliminated(x int) {
	// switch x {
	// case 1:int: print(1:int)
	// case 1:int: print("1a":string)
	// case 2:int: print(2:int)
	// default: return
	// }
	if x == 1 {
		print(1)
	} else if x == 1 { // duplicate => unreachable
		print("1a")
	} else if x == 2 {
		print(2)
	}
}

// Interface values (created by comparisons) are not constants,
// so ConstSwitch.X is never of interface type.
func MakeInterfaceIsNotAConstant(x interface{}) {
	if x == "foo" {
		print("foo")
	} else if x == 1 {
		print(1)
	}
}

func ZeroInitializedVarsAreConstants(x int) {
	// switch x {
	// case 0:int: print(1:int)
	// case 2:int: print(2:int)
	// default: print("end":string)
	// }
	var zero int // SSA construction replaces zero with 0
	if x == zero {
		print(1)
	} else if x == 2 {
		print(2)
	}
	print("end")
}

// -------- Select --------

// NB, potentially fragile reliance on register number.
func SelectDesugarsToSwitch(ch chan int) {
	// switch t1 {
	// case 0:int: extract t0 #2
	// case 1:int: println(0:int)
	// case 2:int: println(1:int)
	// default: println("default":string)
	// }
	select {
	case x := <-ch:
		println(x)
	case <-ch:
		println(0)
	case ch <- 1:
		println(1)
	default:
		println("default")
	}
}

// NB, potentially fragile reliance on register number.
func NonblockingSelectDefaultCasePanics(ch chan int) {
	// switch t1 {
	// case 0:int: extract t0 #2
	// case 1:int: println(0:int)
	// case 2:int: println(1:int)
	// default: make interface{} <- string ("blocking select m...":string)
	// }
	select {
	case x := <-ch:
		println(x)
	case <-ch:
		println(0)
	case ch <- 1:
		println(1)
	}
}

// -------- Type switches --------

// NB, reliance on fragile register numbering.
func SimpleTypeSwitch(x interface{}) {
	// switch x.(type) {
	// case t3 int: println(x)
	// case t7 bool: println(x)
	// case t10 string: println(t10)
	// default: println(x)
	// }
	switch y := x.(type) {
	case nil:
		println(y)
	case int, bool:
		println(y)
	case string:
		println(y)
	default:
		println(y)
	}
}

// NB, potentially fragile reliance on register number.
func DuplicateTypesAreNotEliminated(x interface{}) {
	// switch x.(type) {
	// case t1 string: println(1:int)
	// case t5 interface{}: println(t5)
	// case t9 int: println(3:int)
	// default: return
	// }
	switch y := x.(type) {
	case string:
		println(1)
	case interface{}:
		println(y)
	case int:
		println(3) // unreachable!
	}
}

// NB, potentially fragile reliance on register number.
func AdHocTypeSwitch(x interface{}) {
	// switch x.(type) {
	// case t1 int: println(t1)
	// case t5 string: println(t5)
	// default: print("default":string)
	// }
	if i, ok := x.(int); ok {
		println(i)
	} else if s, ok := x.(string); ok {
		println(s)
	} else {
		print("default")
	}
}


================================================
FILE: go/ssa/ssautil/visit.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssautil // import "golang.org/x/tools/go/ssa/ssautil"

import (
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/ssa"

	_ "unsafe" // for linkname hack
)

// This file defines utilities for visiting the SSA representation of
// a Program.
//
// TODO(adonovan): test coverage.

// AllFunctions finds and returns the set of functions potentially
// needed by program prog, as determined by a simple linker-style
// reachability algorithm starting from the members and method-sets of
// each package.  The result may include anonymous functions and
// synthetic wrappers.
//
// Precondition: all packages are built.
//
// TODO(adonovan): this function is underspecified. It doesn't
// actually work like a linker, which computes reachability from main
// using something like go/callgraph/cha (without materializing the
// call graph). In fact, it treats all public functions and all
// methods of public non-parameterized types as roots, even though
// they may be unreachable--but only in packages created from syntax.
//
// I think we should deprecate AllFunctions function in favor of two
// clearly defined ones:
//
//  1. The first would efficiently compute CHA reachability from a set
//     of main packages, making it suitable for a whole-program
//     analysis context with InstantiateGenerics, in conjunction with
//     Program.Build.
//
//  2. The second would return only the set of functions corresponding
//     to source Func{Decl,Lit} syntax, like SrcFunctions in
//     go/analysis/passes/buildssa; this is suitable for
//     package-at-a-time (or handful of packages) context.
//     ssa.Package could easily expose it as a field.
//
// We could add them unexported for now and use them via the linkname hack.
func AllFunctions(prog *ssa.Program) map[*ssa.Function]bool {
	seen := make(map[*ssa.Function]bool)

	var function func(fn *ssa.Function)
	function = func(fn *ssa.Function) {
		if !seen[fn] {
			seen[fn] = true
			var buf [10]*ssa.Value // avoid alloc in common case
			for _, b := range fn.Blocks {
				for _, instr := range b.Instrs {
					for _, op := range instr.Operands(buf[:0]) {
						if fn, ok := (*op).(*ssa.Function); ok {
							function(fn)
						}
					}
				}
			}
		}
	}

	// TODO(adonovan): opt: provide a way to share a builder
	// across a sequence of MethodValue calls.

	methodsOf := func(T types.Type) {
		if !types.IsInterface(T) {
			mset := prog.MethodSets.MethodSet(T)
			for method := range mset.Methods() {
				function(prog.MethodValue(method))
			}
		}
	}

	// Historically, Program.RuntimeTypes used to include the type
	// of any exported member of a package loaded from syntax that
	// has a non-parameterized type, plus all types
	// reachable from that type using reflection, even though
	// these runtime types may not be required for them.
	//
	// Rather than break existing programs that rely on
	// AllFunctions visiting extra methods that are unreferenced
	// by IR and unreachable via reflection, we moved the logic
	// here, unprincipled though it is.
	// (See doc comment for better ideas.)
	//
	// Nonetheless, after the move, we no longer visit every
	// method of any type recursively reachable from T, only the
	// methods of T and *T themselves, and we only apply this to
	// named types T, and not to the type of every exported
	// package member.
	exportedTypeHack := func(t *ssa.Type) {
		if isSyntactic(t.Package()) &&
			ast.IsExported(t.Name()) &&
			!types.IsInterface(t.Type()) {
			// Consider only named types.
			// (Ignore aliases and unsafe.Pointer.)
			if named, ok := t.Type().(*types.Named); ok {
				if named.TypeParams() == nil {
					methodsOf(named)                   //  T
					methodsOf(types.NewPointer(named)) // *T
				}
			}
		}
	}

	for _, pkg := range prog.AllPackages() {
		for _, mem := range pkg.Members {
			switch mem := mem.(type) {
			case *ssa.Function:
				// Visit all package-level declared functions.
				function(mem)

			case *ssa.Type:
				exportedTypeHack(mem)
			}
		}
	}

	// Visit all methods of types for which runtime types were
	// materialized, as they are reachable through reflection.
	for _, T := range prog.RuntimeTypes() {
		methodsOf(T)
	}

	return seen
}

// MainPackages returns the subset of the specified packages
// named "main" that define a main function.
// The result may include synthetic "testmain" packages.
func MainPackages(pkgs []*ssa.Package) []*ssa.Package {
	var mains []*ssa.Package
	for _, pkg := range pkgs {
		if pkg.Pkg.Name() == "main" && pkg.Func("main") != nil {
			mains = append(mains, pkg)
		}
	}
	return mains
}

// TODO(adonovan): propose a principled API for this. One possibility
// is a new field, Package.SrcFunctions []*Function, which would
// contain the list of SrcFunctions described in point 2 of the
// AllFunctions doc comment, or nil if the package is not from syntax.
// But perhaps overloading nil vs empty slice is too subtle.
//
//go:linkname isSyntactic golang.org/x/tools/go/ssa.isSyntactic
func isSyntactic(pkg *ssa.Package) bool


================================================
FILE: go/ssa/stdlib_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Incomplete source tree on Android.

//go:build !android

package ssa_test

// This file runs the SSA builder in sanity-checking mode on all
// packages beneath $GOROOT and prints some summary information.
//
// Run with "go test -cpu=8 to" set GOMAXPROCS.

import (
	"go/ast"
	"go/token"
	"go/types"
	"runtime"
	"testing"
	"time"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
)

func bytesAllocated() uint64 {
	runtime.GC()
	var stats runtime.MemStats
	runtime.ReadMemStats(&stats)
	return stats.Alloc
}

// TestStdlib loads the entire standard library and its tools and all
// their dependencies.
//
// (As of go1.23, std is transitively closed, so adding the -deps flag
// doesn't increase its result set. The cmd pseudomodule of course
// depends on a good chunk of std, but the std+cmd set is also
// transitively closed, so long as -pgo=off.)
//
// Apart from a small number of internal packages that are not
// returned by the 'std' query, the set is essentially transitively
// closed, so marginal per-dependency costs are invisible.
func TestStdlib(t *testing.T) {
	testLoad(t, 500, "std", "cmd")
}

// TestNetHTTP builds a single SSA package but not its dependencies.
// It may help reveal costs related to dependencies (e.g. unnecessary building).
func TestNetHTTP(t *testing.T) {
	testLoad(t, 120, "net/http")
}

// TestCycles loads two standard libraries that depend on the same
// generic instantiations.
// internal/trace/testtrace and net/http both depend on
// slices.Contains[[]string string] and slices.Index[[]string string]
// This can under some schedules create a cycle of dependencies
// where both need to wait on the other to finish building.
func TestCycles(t *testing.T) {
	testenv.NeedsGo1Point(t, 23) // internal/trace/testtrace was added in 1.23.
	testLoad(t, 120, "net/http", "internal/trace/testtrace")
}

func testLoad(t *testing.T, minPkgs int, patterns ...string) {
	// Note: most of the commentary below applies to TestStdlib.

	if testing.Short() {
		t.Skip("skipping in short mode; too slow (https://golang.org/issue/14113)") // ~5s
	}
	testenv.NeedsTool(t, "go")

	// Load, parse and type-check the program.
	t0 := time.Now()
	alloc0 := bytesAllocated()

	cfg := &packages.Config{Mode: packages.LoadSyntax}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		t.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		t.Fatal("there were errors loading the packages")
	}

	t1 := time.Now()
	alloc1 := bytesAllocated()

	// Create SSA packages.
	var mode ssa.BuilderMode
	// Comment out these lines during benchmarking.  Approx SSA build costs are noted.
	mode |= ssa.SanityCheckFunctions // + 2% space, + 4% time
	mode |= ssa.GlobalDebug          // +30% space, +18% time
	mode |= ssa.InstantiateGenerics  // + 0% space, + 2% time (unlikely to reproduce outside of stdlib)
	prog, _ := ssautil.Packages(pkgs, mode)

	t2 := time.Now()

	// Build SSA.
	prog.Build()

	t3 := time.Now()
	alloc3 := bytesAllocated()

	// Sanity check to ensure we haven't dropped large numbers of packages.
	numPkgs := len(prog.AllPackages())
	if numPkgs < minPkgs {
		t.Errorf("Loaded only %d packages, want at least %d", numPkgs, minPkgs)
	}

	// Keep pkgs reachable until after we've measured memory usage.
	if len(pkgs) == 0 {
		panic("unreachable")
	}

	srcFuncs := srcFunctions(prog, pkgs)
	allFuncs := ssautil.AllFunctions(prog)

	// The assertion below is not valid if the program contains
	// variants of the same package, such as the test variants
	// (e.g. package p as compiled for test executable x) obtained
	// when cfg.Tests=true. Profile-guided optimization may
	// lead to similar variation for non-test executables.
	//
	// Ideally, the test would assert that all functions within
	// each executable (more generally: within any singly rooted
	// transitively closed subgraph of the import graph) have
	// distinct names, but that isn't so easy to compute efficiently.
	// Disabling for now.
	if false {
		// Check that all non-synthetic functions have distinct names.
		// Synthetic wrappers for exported methods should be distinct too,
		// except for unexported ones (explained at (*Function).RelString).
		byName := make(map[string]*ssa.Function)
		for fn := range allFuncs {
			if fn.Synthetic == "" || ast.IsExported(fn.Name()) {
				str := fn.String()
				prev := byName[str]
				byName[str] = fn
				if prev != nil {
					t.Errorf("%s: duplicate function named %s",
						prog.Fset.Position(fn.Pos()), str)
					t.Errorf("%s:   (previously defined here)",
						prog.Fset.Position(prev.Pos()))
				}
			}
		}
	}

	// Dump some statistics.
	var numInstrs int
	for fn := range allFuncs {
		for _, b := range fn.Blocks {
			numInstrs += len(b.Instrs)
		}
	}

	// determine line count
	var lineCount int
	prog.Fset.Iterate(func(f *token.File) bool {
		lineCount += f.LineCount()
		return true
	})

	// NB: when benchmarking, don't forget to clear the debug +
	// sanity builder flags for better performance.

	t.Log("GOMAXPROCS:           ", runtime.GOMAXPROCS(0))
	t.Log("#Source lines:        ", lineCount)
	t.Log("Load/parse/typecheck: ", t1.Sub(t0))
	t.Log("SSA create:           ", t2.Sub(t1))
	t.Log("SSA build:            ", t3.Sub(t2))

	// SSA stats:
	t.Log("#Packages:            ", numPkgs)
	t.Log("#SrcFunctions:        ", len(srcFuncs))
	t.Log("#AllFunctions:        ", len(allFuncs))
	t.Log("#Instructions:        ", numInstrs)
	t.Log("#MB AST+types:        ", int64(alloc1-alloc0)/1e6)
	t.Log("#MB SSA:              ", int64(alloc3-alloc1)/1e6)
}

// srcFunctions gathers all ssa.Functions corresponding to syntax.
// (Includes generics but excludes instances and all wrappers.)
//
// This is essentially identical to the SrcFunctions logic in
// go/analysis/passes/buildssa.
func srcFunctions(prog *ssa.Program, pkgs []*packages.Package) (res []*ssa.Function) {
	var addSrcFunc func(fn *ssa.Function)
	addSrcFunc = func(fn *ssa.Function) {
		res = append(res, fn)
		for _, anon := range fn.AnonFuncs {
			addSrcFunc(anon)
		}
	}
	for _, pkg := range pkgs {
		for _, file := range pkg.Syntax {
			for _, decl := range file.Decls {
				if decl, ok := decl.(*ast.FuncDecl); ok {
					obj := pkg.TypesInfo.Defs[decl.Name].(*types.Func)
					if obj == nil {
						panic("nil *types.Func: " + decl.Name.Name)
					}
					fn := prog.FuncValue(obj)
					if fn == nil {
						panic("nil *ssa.Function: " + obj.String())
					}
					addSrcFunc(fn)
				}
			}
		}
	}
	return res
}


================================================
FILE: go/ssa/subst.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/aliases"
)

// subster defines a type substitution operation of a set of type parameters
// to type parameter free replacement types. Substitution is done within
// the context of a package-level function instantiation. *Named types
// declared in the function are unique to the instantiation.
//
// For example, given a parameterized function F
//
//	  func F[S, T any]() any {
//	    type X struct{ s S; next *X }
//		var p *X
//	    return p
//	  }
//
// calling the instantiation F[string, int]() returns an interface
// value (*X[string,int], nil) where the underlying value of
// X[string,int] is a struct{s string; next *X[string,int]}.
//
// A nil *subster is a valid, empty substitution map. It always acts as
// the identity function. This allows for treating parameterized and
// non-parameterized functions identically while compiling to ssa.
//
// Not concurrency-safe.
//
// Note: Some may find it helpful to think through some of the most
// complex substitution cases using lambda calculus inspired notation.
// subst.typ() solves evaluating a type expression E
// within the body of a function Fn[m] with the type parameters m
// once we have applied the type arguments N.
// We can succinctly write this as a function application:
//
//	((λm. E) N)
//
// go/types does not provide this interface directly.
// So what subster provides is a type substitution operation
//
//	E[m:=N]
type subster struct {
	replacements map[*types.TypeParam]types.Type // values should contain no type params
	cache        map[types.Type]types.Type       // cache of subst results
	origin       *types.Func                     // types.Objects declared within this origin function are unique within this context
	ctxt         *types.Context                  // speeds up repeated instantiations
	uniqueness   typeutil.Map                    // determines the uniqueness of the instantiations within the function
	// TODO(taking): consider adding Pos
}

// Returns a subster that replaces tparams[i] with targs[i]. Uses ctxt as a cache.
// targs should not contain any types in tparams.
// fn is the generic function for which we are substituting.
func makeSubster(ctxt *types.Context, fn *types.Func, tparams *types.TypeParamList, targs []types.Type) *subster {
	assert(tparams.Len() == len(targs), "makeSubster argument count must match")

	subst := &subster{
		replacements: make(map[*types.TypeParam]types.Type, tparams.Len()),
		cache:        make(map[types.Type]types.Type),
		origin:       fn.Origin(),
		ctxt:         ctxt,
	}
	for i := 0; i < tparams.Len(); i++ {
		subst.replacements[tparams.At(i)] = targs[i]
	}
	return subst
}

// typ returns the type of t with the type parameter tparams[i] substituted
// for the type targs[i] where subst was created using tparams and targs.
func (subst *subster) typ(t types.Type) (res types.Type) {
	if subst == nil {
		return t // A nil subst is type preserving.
	}
	if r, ok := subst.cache[t]; ok {
		return r
	}
	defer func() {
		subst.cache[t] = res
	}()

	switch t := t.(type) {
	case *types.TypeParam:
		if r := subst.replacements[t]; r != nil {
			return r
		}
		return t

	case *types.Basic:
		return t

	case *types.Array:
		if r := subst.typ(t.Elem()); r != t.Elem() {
			return types.NewArray(r, t.Len())
		}
		return t

	case *types.Slice:
		if r := subst.typ(t.Elem()); r != t.Elem() {
			return types.NewSlice(r)
		}
		return t

	case *types.Pointer:
		if r := subst.typ(t.Elem()); r != t.Elem() {
			return types.NewPointer(r)
		}
		return t

	case *types.Tuple:
		return subst.tuple(t)

	case *types.Struct:
		return subst.struct_(t)

	case *types.Map:
		key := subst.typ(t.Key())
		elem := subst.typ(t.Elem())
		if key != t.Key() || elem != t.Elem() {
			return types.NewMap(key, elem)
		}
		return t

	case *types.Chan:
		if elem := subst.typ(t.Elem()); elem != t.Elem() {
			return types.NewChan(t.Dir(), elem)
		}
		return t

	case *types.Signature:
		return subst.signature(t)

	case *types.Union:
		return subst.union(t)

	case *types.Interface:
		return subst.interface_(t)

	case *types.Alias:
		return subst.alias(t)

	case *types.Named:
		return subst.named(t)

	case *opaqueType:
		return t // opaque types are never substituted

	default:
		panic("unreachable")
	}
}

// types returns the result of {subst.typ(ts[i])}.
func (subst *subster) types(ts []types.Type) []types.Type {
	res := make([]types.Type, len(ts))
	for i := range ts {
		res[i] = subst.typ(ts[i])
	}
	return res
}

func (subst *subster) tuple(t *types.Tuple) *types.Tuple {
	if t != nil {
		if vars := subst.varlist(t); vars != nil {
			return types.NewTuple(vars...)
		}
	}
	return t
}

type varlist interface {
	At(i int) *types.Var
	Len() int
}

// fieldlist is an adapter for structs for the varlist interface.
type fieldlist struct {
	str *types.Struct
}

func (fl fieldlist) At(i int) *types.Var { return fl.str.Field(i) }
func (fl fieldlist) Len() int            { return fl.str.NumFields() }

func (subst *subster) struct_(t *types.Struct) *types.Struct {
	if t != nil {
		if fields := subst.varlist(fieldlist{t}); fields != nil {
			tags := make([]string, t.NumFields())
			for i, n := 0, t.NumFields(); i < n; i++ {
				tags[i] = t.Tag(i)
			}
			return types.NewStruct(fields, tags)
		}
	}
	return t
}

// varlist returns subst(in[i]) or return nils if subst(v[i]) == v[i] for all i.
func (subst *subster) varlist(in varlist) []*types.Var {
	var out []*types.Var // nil => no updates
	for i, n := 0, in.Len(); i < n; i++ {
		v := in.At(i)
		w := subst.var_(v)
		if v != w && out == nil {
			out = make([]*types.Var, n)
			for j := 0; j < i; j++ {
				out[j] = in.At(j)
			}
		}
		if out != nil {
			out[i] = w
		}
	}
	return out
}

func (subst *subster) var_(v *types.Var) *types.Var {
	if v != nil {
		if typ := subst.typ(v.Type()); typ != v.Type() {
			if v.IsField() {
				return types.NewField(v.Pos(), v.Pkg(), v.Name(), typ, v.Embedded())
			}
			return types.NewParam(v.Pos(), v.Pkg(), v.Name(), typ)
		}
	}
	return v
}

func (subst *subster) union(u *types.Union) *types.Union {
	var out []*types.Term // nil => no updates

	for i, n := 0, u.Len(); i < n; i++ {
		t := u.Term(i)
		r := subst.typ(t.Type())
		if r != t.Type() && out == nil {
			out = make([]*types.Term, n)
			for j := 0; j < i; j++ {
				out[j] = u.Term(j)
			}
		}
		if out != nil {
			out[i] = types.NewTerm(t.Tilde(), r)
		}
	}

	if out != nil {
		return types.NewUnion(out)
	}
	return u
}

func (subst *subster) interface_(iface *types.Interface) *types.Interface {
	if iface == nil {
		return nil
	}

	// methods for the interface. Initially nil if there is no known change needed.
	// Signatures for the method where recv is nil. NewInterfaceType fills in the receivers.
	var methods []*types.Func
	initMethods := func(n int) { // copy first n explicit methods
		methods = make([]*types.Func, iface.NumExplicitMethods())
		for i := range n {
			f := iface.ExplicitMethod(i)
			norecv := changeRecv(f.Type().(*types.Signature), nil)
			methods[i] = types.NewFunc(f.Pos(), f.Pkg(), f.Name(), norecv)
		}
	}
	for i := 0; i < iface.NumExplicitMethods(); i++ {
		f := iface.ExplicitMethod(i)
		// On interfaces, we need to cycle break on anonymous interface types
		// being in a cycle with their signatures being in cycles with their receivers
		// that do not go through a Named.
		norecv := changeRecv(f.Type().(*types.Signature), nil)
		sig := subst.typ(norecv)
		if sig != norecv && methods == nil {
			initMethods(i)
		}
		if methods != nil {
			methods[i] = types.NewFunc(f.Pos(), f.Pkg(), f.Name(), sig.(*types.Signature))
		}
	}

	var embeds []types.Type
	initEmbeds := func(n int) { // copy first n embedded types
		embeds = make([]types.Type, iface.NumEmbeddeds())
		for i := range n {
			embeds[i] = iface.EmbeddedType(i)
		}
	}
	for i := 0; i < iface.NumEmbeddeds(); i++ {
		e := iface.EmbeddedType(i)
		r := subst.typ(e)
		if e != r && embeds == nil {
			initEmbeds(i)
		}
		if embeds != nil {
			embeds[i] = r
		}
	}

	if methods == nil && embeds == nil {
		return iface
	}
	if methods == nil {
		initMethods(iface.NumExplicitMethods())
	}
	if embeds == nil {
		initEmbeds(iface.NumEmbeddeds())
	}
	return types.NewInterfaceType(methods, embeds).Complete()
}

func (subst *subster) alias(t *types.Alias) types.Type {
	// See subster.named. This follows the same strategy.
	tparams := t.TypeParams()
	targs := t.TypeArgs()
	tname := t.Obj()
	torigin := t.Origin()

	if !declaredWithin(tname, subst.origin) {
		// t is declared outside of the function origin. So t is a package level type alias.
		if targs.Len() == 0 {
			// No type arguments so no instantiation needed.
			return t
		}

		// Instantiate with the substituted type arguments.
		newTArgs := subst.typelist(targs)
		return subst.instantiate(torigin, newTArgs)
	}

	if targs.Len() == 0 {
		// t is declared within the function origin and has no type arguments.
		//
		// Example: This corresponds to A or B in F, but not A[int]:
		//
		//     func F[T any]() {
		//       type A[S any] = struct{t T, s S}
		//       type B = T
		//       var x A[int]
		//       ...
		//     }
		//
		// This is somewhat different than *Named as *Alias cannot be created recursively.

		// Copy and substitute type params.
		var newTParams []*types.TypeParam
		for cur := range tparams.TypeParams() {
			cobj := cur.Obj()
			cname := types.NewTypeName(cobj.Pos(), cobj.Pkg(), cobj.Name(), nil)
			ntp := types.NewTypeParam(cname, nil)
			subst.cache[cur] = ntp // See the comment "Note: Subtle" in subster.named.
			newTParams = append(newTParams, ntp)
		}

		// Substitute rhs.
		rhs := subst.typ(t.Rhs())

		// Create the fresh alias.
		obj := aliases.New(tname.Pos(), tname.Pkg(), tname.Name(), rhs, newTParams)

		// Substitute into all of the constraints after they are created.
		for i, ntp := range newTParams {
			bound := tparams.At(i).Constraint()
			ntp.SetConstraint(subst.typ(bound))
		}
		return obj.Type()
	}

	// t is declared within the function origin and has type arguments.
	//
	// Example: This corresponds to A[int] in F. Cases A and B are handled above.
	//     func F[T any]() {
	//       type A[S any] = struct{t T, s S}
	//       type B = T
	//       var x A[int]
	//       ...
	//     }
	subOrigin := subst.typ(torigin)
	subTArgs := subst.typelist(targs)
	return subst.instantiate(subOrigin, subTArgs)
}

func (subst *subster) named(t *types.Named) types.Type {
	// A Named type is a user defined type.
	// Ignoring generics, Named types are canonical: they are identical if
	// and only if they have the same defining symbol.
	// Generics complicate things, both if the type definition itself is
	// parameterized, and if the type is defined within the scope of a
	// parameterized function. In this case, two named types are identical if
	// and only if their identifying symbols are identical, and all type
	// arguments bindings in scope of the named type definition (including the
	// type parameters of the definition itself) are equivalent.
	//
	// Notably:
	// 1. For type definition type T[P1 any] struct{}, T[A] and T[B] are identical
	//    only if A and B are identical.
	// 2. Inside the generic func Fn[m any]() any { type T struct{}; return T{} },
	//    the result of Fn[A] and Fn[B] have identical type if and only if A and
	//    B are identical.
	// 3. Both 1 and 2 could apply, such as in
	//    func F[m any]() any { type T[x any] struct{}; return T{} }
	//
	// A subster replaces type parameters within a function scope, and therefore must
	// also replace free type parameters in the definitions of local types.
	//
	// Note: There are some detailed notes sprinkled throughout that borrow from
	// lambda calculus notation. These contain some over simplifying math.
	//
	// LC: One way to think about subster is that it is  a way of evaluating
	//   ((λm. E) N) as E[m:=N].
	// Each Named type t has an object *TypeName within a scope S that binds an
	// underlying type expression U. U can refer to symbols within S (+ S's ancestors).
	// Let x = t.TypeParams() and A = t.TypeArgs().
	// Each Named type t is then either:
	//   U              where len(x) == 0 && len(A) == 0
	//   λx. U          where len(x) != 0 && len(A) == 0
	//   ((λx. U) A)    where len(x) == len(A)
	// In each case, we will evaluate t[m:=N].
	tparams := t.TypeParams() // x
	targs := t.TypeArgs()     // A

	if !declaredWithin(t.Obj(), subst.origin) {
		// t is declared outside of Fn[m].
		//
		// In this case, we can skip substituting t.Underlying().
		// The underlying type cannot refer to the type parameters.
		//
		// LC: Let free(E) be the set of free type parameters in an expression E.
		// Then whenever m ∉ free(E), then E = E[m:=N].
		// t ∉ Scope(fn) so therefore m ∉ free(U) and m ∩ x = ∅.
		if targs.Len() == 0 {
			// t has no type arguments. So it does not need to be instantiated.
			//
			// This is the normal case in real Go code, where t is not parameterized,
			// declared at some package scope, and m is a TypeParam from a parameterized
			// function F[m] or method.
			//
			// LC: m ∉ free(A) lets us conclude m ∉ free(t). So t=t[m:=N].
			return t
		}

		// t is declared outside of Fn[m] and has type arguments.
		// The type arguments may contain type parameters m so
		// substitute the type arguments, and instantiate the substituted
		// type arguments.
		//
		// LC: Evaluate this as ((λx. U) A') where A' = A[m := N].
		newTArgs := subst.typelist(targs)
		return subst.instantiate(t.Origin(), newTArgs)
	}

	// t is declared within Fn[m].

	if targs.Len() == 0 { // no type arguments?
		assert(t == t.Origin(), "local parameterized type abstraction must be an origin type")

		// t has no type arguments.
		// The underlying type of t may contain the function's type parameters,
		// replace these, and create a new type.
		//
		// Subtle: We short circuit substitution and use a newly created type in
		// subst, i.e. cache[t]=fresh, to preemptively replace t with fresh
		// in recursive types during traversal. This both breaks infinite cycles
		// and allows for constructing types with the replacement applied in
		// subst.typ(U).
		//
		// A new copy of the Named and Typename (and constraints) per function
		// instantiation matches the semantics of Go, which treats all function
		// instantiations F[N] as having distinct local types.
		//
		// LC: x.Len()=0 can be thought of as a special case of λx. U.
		// LC: Evaluate (λx. U)[m:=N] as (λx'. U') where U'=U[x:=x',m:=N].
		tname := t.Obj()
		obj := types.NewTypeName(tname.Pos(), tname.Pkg(), tname.Name(), nil)
		fresh := types.NewNamed(obj, nil, nil)
		var newTParams []*types.TypeParam
		for cur := range tparams.TypeParams() {
			cobj := cur.Obj()
			cname := types.NewTypeName(cobj.Pos(), cobj.Pkg(), cobj.Name(), nil)
			ntp := types.NewTypeParam(cname, nil)
			subst.cache[cur] = ntp
			newTParams = append(newTParams, ntp)
		}
		fresh.SetTypeParams(newTParams)
		subst.cache[t] = fresh
		subst.cache[fresh] = fresh
		fresh.SetUnderlying(subst.typ(t.Underlying()))
		// Substitute into all of the constraints after they are created.
		for i, ntp := range newTParams {
			bound := tparams.At(i).Constraint()
			ntp.SetConstraint(subst.typ(bound))
		}
		return fresh
	}

	// t is defined within Fn[m] and t has type arguments (an instantiation).
	// We reduce this to the two cases above:
	// (1) substitute the function's type parameters into t.Origin().
	// (2) substitute t's type arguments A and instantiate the updated t.Origin() with these.
	//
	// LC: Evaluate ((λx. U) A)[m:=N] as (t' A') where t' = (λx. U)[m:=N] and A'=A [m:=N]
	subOrigin := subst.typ(t.Origin())
	subTArgs := subst.typelist(targs)
	return subst.instantiate(subOrigin, subTArgs)
}

func (subst *subster) instantiate(orig types.Type, targs []types.Type) types.Type {
	i, err := types.Instantiate(subst.ctxt, orig, targs, false)
	assert(err == nil, "failed to Instantiate named (Named or Alias) type")
	if c, _ := subst.uniqueness.At(i).(types.Type); c != nil {
		return c.(types.Type)
	}
	subst.uniqueness.Set(i, i)
	return i
}

func (subst *subster) typelist(l *types.TypeList) []types.Type {
	res := make([]types.Type, l.Len())
	for i := 0; i < l.Len(); i++ {
		res[i] = subst.typ(l.At(i))
	}
	return res
}

func (subst *subster) signature(t *types.Signature) types.Type {
	tparams := t.TypeParams()

	// We are choosing not to support tparams.Len() > 0 until a need has been observed in practice.
	//
	// There are some known usages for types.Types coming from types.{Eval,CheckExpr}.
	// To support tparams.Len() > 0, we just need to do the following [pseudocode]:
	//   targs := {subst.replacements[tparams[i]]]}; Instantiate(ctxt, t, targs, false)

	assert(tparams.Len() == 0, "Substituting types.Signatures with generic functions are currently unsupported.")

	// Either:
	// (1)non-generic function.
	//    no type params to substitute
	// (2)generic method and recv needs to be substituted.

	// Receivers can be either:
	// named
	// pointer to named
	// interface
	// nil
	// interface is the problematic case. We need to cycle break there!
	recv := subst.var_(t.Recv())
	params := subst.tuple(t.Params())
	results := subst.tuple(t.Results())
	if recv != t.Recv() || params != t.Params() || results != t.Results() {
		return types.NewSignatureType(recv, nil, nil, params, results, t.Variadic())
	}
	return t
}


================================================
FILE: go/ssa/subst_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"
)

func TestSubst(t *testing.T) {
	const source = `
package P

func within(){
	// Pretend that the instantiation happens within this function.
}

type t0 int
func (t0) f()
type t1 interface{ f() }
type t2 interface{ g() }
type t3 interface{ ~int }

func Fn0[T t1](x T) T {
	x.f()
	return x
}

type A[T any] [4]T
type B[T any] []T
type C[T, S any] []struct{s S; t T}
type D[T, S any] *struct{s S; t *T}
type E[T, S any] interface{ F() (T, S) }
type F[K comparable, V any] map[K]V
type G[T any] chan *T
type H[T any] func() T
type I[T any] struct{x, y, z int; t T}
type J[T any] interface{ t1 }
type K[T any] interface{ t1; F() T }
type L[T any] interface{ F() T; J[T] }

var _ L[int] = Fn0[L[int]](nil)
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	within, _ := pkg.Scope().Lookup("within").(*types.Func)
	if within == nil {
		t.Fatal("Failed to find the function within()")
	}

	for _, test := range []struct {
		expr string   // type expression of Named parameterized type
		args []string // type expressions of args for named
		want string   // expected underlying value after substitution
	}{
		{"A", []string{"string"}, "[4]string"},
		{"A", []string{"int"}, "[4]int"},
		{"B", []string{"int"}, "[]int"},
		{"B", []string{"int8"}, "[]int8"},
		{"C", []string{"int8", "string"}, "[]struct{s string; t int8}"},
		{"C", []string{"string", "int8"}, "[]struct{s int8; t string}"},
		{"D", []string{"int16", "string"}, "*struct{s string; t *int16}"},
		{"E", []string{"int32", "string"}, "interface{F() (int32, string)}"},
		{"F", []string{"int64", "string"}, "map[int64]string"},
		{"G", []string{"uint64"}, "chan *uint64"},
		{"H", []string{"uintptr"}, "func() uintptr"},
		{"I", []string{"t0"}, "struct{x int; y int; z int; t P.t0}"},
		{"J", []string{"t0"}, "interface{P.t1}"},
		{"K", []string{"t0"}, "interface{F() P.t0; P.t1}"},
		{"L", []string{"t0"}, "interface{F() P.t0; P.J[P.t0]}"},
		{"L", []string{"L[t0]"}, "interface{F() P.L[P.t0]; P.J[P.L[P.t0]]}"},
	} {
		// Eval() expr for its type.
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Fatalf("Eval(%s) failed: %v", test.expr, err)
		}
		// Eval() test.args[i] to get the i'th type arg.
		var targs []types.Type
		for _, astr := range test.args {
			tv, err := types.Eval(fset, pkg, 0, astr)
			if err != nil {
				t.Fatalf("Eval(%s) failed: %v", astr, err)
			}
			targs = append(targs, tv.Type)
		}

		T := tv.Type.(*types.Named)

		subst := makeSubster(types.NewContext(), within, T.TypeParams(), targs)
		sub := subst.typ(T.Underlying())
		if got := sub.String(); got != test.want {
			t.Errorf("subst{%v->%v}.typ(%s) = %v, want %v", test.expr, test.args, T.Underlying(), got, test.want)
		}
	}
}


================================================
FILE: go/ssa/task.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"sync/atomic"
)

// Each task has two states: it is initially "active",
// and transitions to "done".
//
// tasks form a directed graph. An edge from x to y (with y in x.edges)
// indicates that the task x waits on the task y to be done.
// Cycles are permitted.
//
// Calling x.wait() blocks the calling goroutine until task x,
// and all the tasks transitively reachable from x are done.
//
// The nil *task is always considered done.
type task struct {
	done       chan unit      // close when the task is done.
	edges      map[*task]unit // set of predecessors of this task.
	transitive atomic.Bool    // true once it is known all predecessors are done.
}

func (x *task) isTransitivelyDone() bool { return x == nil || x.transitive.Load() }

// addEdge creates an edge from x to y, indicating that
// x.wait() will not return before y is done.
// All calls to x.addEdge(...) should happen before x.markDone().
func (x *task) addEdge(y *task) {
	if x == y || y.isTransitivelyDone() {
		return // no work remaining
	}

	// heuristic done check
	select {
	case <-x.done:
		panic("cannot add an edge to a done task")
	default:
	}

	if x.edges == nil {
		x.edges = make(map[*task]unit)
	}
	x.edges[y] = unit{}
}

// markDone changes the task's state to markDone.
func (x *task) markDone() {
	if x != nil {
		close(x.done)
	}
}

// wait blocks until x and all the tasks it can reach through edges are done.
func (x *task) wait() {
	if x.isTransitivelyDone() {
		return // already known to be done. Skip allocations.
	}

	// Use BFS to wait on u.done to be closed, for all u transitively
	// reachable from x via edges.
	//
	// This work can be repeated by multiple workers doing wait().
	//
	// Note: Tarjan's SCC algorithm is able to mark SCCs as transitively done
	// as soon as the SCC has been visited. This is theoretically faster, but is
	// a more complex algorithm. Until we have evidence, we need the more complex
	// algorithm, the simpler algorithm BFS is implemented.
	//
	// In Go 1.23, ssa/TestStdlib reaches <=3 *tasks per wait() in most schedules
	// On some schedules, there is a cycle building net/http and internal/trace/testtrace
	// due to slices functions.
	work := []*task{x}
	enqueued := map[*task]unit{x: {}}
	for i := 0; i < len(work); i++ {
		u := work[i]
		if u.isTransitivelyDone() { // already transitively done
			work[i] = nil
			continue
		}
		<-u.done // wait for u to be marked done.

		for v := range u.edges {
			if _, ok := enqueued[v]; !ok {
				enqueued[v] = unit{}
				work = append(work, v)
			}
		}
	}

	// work is transitively closed over dependencies.
	// u in work is done (or transitively done and skipped).
	// u is transitively done.
	for _, u := range work {
		if u != nil {
			x.transitive.Store(true)
		}
	}
}


================================================
FILE: go/ssa/testdata/fixedbugs/issue66783a.go
================================================
//go:build ignore
// +build ignore

package issue66783a

type S[T any] struct {
	a T
}

func (s S[T]) M() {
	type A S[T]
	type B[U any] A
	_ = B[rune](s)
}

// M[int]

// panic: in (issue66783a.S[int]).M[int]:
// cannot convert term *t0 (issue66783a.S[int] [within struct{a int}])
// to type issue66783a.B[rune] [within struct{a T}] [recovered]

func M() {
	S[int]{}.M()
}


================================================
FILE: go/ssa/testdata/fixedbugs/issue66783b.go
================================================
//go:build ignore
// +build ignore

package issue66783b

type I1[T any] interface {
	M(T)
}

type I2[T any] I1[T]

func foo[T any](i I2[T]) {
	_ = i.M
}

type S[T any] struct{}

func (s S[T]) M(t T) {}

func M2() {
	foo[int](I2[int](S[int]{}))
}


================================================
FILE: go/ssa/testdata/fixedbugs/issue73594.go
================================================
package issue73594

// Regression test for sanity-check failure caused by not clearing
// Function.subst after building a body-less instantiated function.

type genericType[T any] struct{}

func (genericType[T]) methodWithoutBody()

func callMethodWithoutBody() {
	msg := &genericType[int]{}
	msg.methodWithoutBody()
}


================================================
FILE: go/ssa/testdata/indirect.txtar
================================================
-- go.mod --
module testdata
go 1.18

-- a/a.go --
package a

import "testdata/b"

func A() {
	var x b.B
	x.F()
}

-- b/b.go --
package b

import "testdata/c"

type B struct { c.C }

-- c/c.go --
package c

type C int
func (C) F() {}

================================================
FILE: go/ssa/testdata/objlookup.go
================================================
package main

// This file is the input to TestObjValueLookup in source_test.go,
// which ensures that each occurrence of an ident defining or
// referring to a func, var or const object can be mapped to its
// corresponding SSA Value.
//
// For every reference to a var object, we use annotations in comments
// to denote both the expected SSA Value kind, and whether to expect
// its value (x) or its address (&x).
//
// For const and func objects, the results don't vary by reference and
// are always values not addresses, so no annotations are needed.  The
// declaration is enough.

import (
	"fmt"
	"os"
)

type J int

func (*J) method() {}

const globalConst = 0

var globalVar int //@ ssa(globalVar,"&Global")

func globalFunc() {}

type I interface {
	interfaceMethod()
}

type S struct {
	x int //@ ssa(x,"nil")
}

func main() {
	print(globalVar) //@ ssa(globalVar,"UnOp")
	globalVar = 1    //@ ssa(globalVar,"Const")

	var v0 int = 1 //@ ssa(v0,"Const") // simple local value spec
	if v0 > 0 {    //@ ssa(v0,"Const")
		v0 = 2 //@ ssa(v0,"Const")
	}
	print(v0) //@ ssa(v0,"Phi")

	// v1 is captured and thus implicitly address-taken.
	var v1 int = 1         //@ ssa(v1,"Const")
	v1 = 2                 //@ ssa(v1,"Const")
	fmt.Println(v1)        //@ ssa(v1,"UnOp") // load
	f := func(param int) { //@ ssa(f,"MakeClosure"), ssa(param,"Parameter")
		if y := 1; y > 0 { //@ ssa(y,"Const")
			print(v1, param) //@ ssa(v1,"UnOp") /*load*/, ssa(param,"Parameter")
		}
		param = 2      //@ ssa(param,"Const")
		println(param) //@ ssa(param,"Const")
	}

	f(0) //@ ssa(f,"MakeClosure")

	var v2 int //@ ssa(v2,"Const") // implicitly zero-initialized local value spec
	print(v2)  //@ ssa(v2,"Const")

	m := make(map[string]int) //@ ssa(m,"MakeMap")

	// Local value spec with multi-valued RHS:
	var v3, v4 = m[""] //@ ssa(v3,"Extract"), ssa(v4,"Extract"), ssa(m,"MakeMap")
	print(v3)          //@ ssa(v3,"Extract")
	print(v4)          //@ ssa(v4,"Extract")

	v3++    //@ ssa(v3,"BinOp") // assign with op
	v3 += 2 //@ ssa(v3,"BinOp") // assign with op

	v5, v6 := false, "" //@ ssa(v5,"Const"), ssa(v6,"Const") // defining assignment
	print(v5)           //@ ssa(v5,"Const")
	print(v6)           //@ ssa(v6,"Const")

	var v7 S    //@ ssa(v7,"&Alloc")
	v7.x = 1    //@ ssa(v7,"&Alloc"), ssa(x,"&FieldAddr")
	print(v7.x) //@ ssa(v7,"&Alloc"), ssa(x,"&FieldAddr")

	var v8 [1]int //@ ssa(v8,"&Alloc")
	v8[0] = 0     //@ ssa(v8,"&Alloc")
	print(v8[:])  //@ ssa(v8,"&Alloc")
	_ = v8[0]     //@ ssa(v8,"&Alloc")
	_ = v8[:][0]  //@ ssa(v8,"&Alloc")
	v8ptr := &v8  //@ ssa(v8ptr,"Alloc"), ssa(v8,"&Alloc")
	_ = v8ptr[0]  //@ ssa(v8ptr,"Alloc")
	_ = *v8ptr    //@ ssa(v8ptr,"Alloc")

	v8a := make([]int, 1) //@ ssa(v8a,"Slice")
	v8a[0] = 0            //@ ssa(v8a,"Slice")
	print(v8a[:])         //@ ssa(v8a,"Slice")

	v9 := S{} //@ ssa(v9,"&Alloc")

	v10 := &v9 //@ ssa(v10,"Alloc"), ssa(v9,"&Alloc")
	_ = v10    //@ ssa(v10,"Alloc")

	var v11 *J = nil //@ ssa(v11,"Const")
	v11.method()     //@ ssa(v11,"Const")

	var v12 J    //@ ssa(v12,"&Alloc")
	v12.method() //@ ssa(v12,"&Alloc") // implicitly address-taken

	// NB, in the following, 'method' resolves to the *types.Func
	// of (*J).method, so it doesn't help us locate the specific
	// ssa.Values here: a bound-method closure and a promotion
	// wrapper.
	_ = v11.method            //@ ssa(v11,"Const")
	_ = (*struct{ J }).method //@ ssa(J,"nil")

	// These vars are not optimised away.
	if false {
		v13 := 0     //@ ssa(v13,"Const")
		println(v13) //@ ssa(v13,"Const")
	}

	switch x := 1; x { //@ ssa(x,"Const")
	case v0: //@ ssa(v0,"Phi")
	}

	for k, v := range m { //@ ssa(k,"Extract"), ssa(v,"Extract"), ssa(m,"MakeMap")
		_ = k //@ ssa(k,"Extract")
		v++   //@ ssa(v,"BinOp")
	}

	if y := 0; y > 1 { //@ ssa(y,"Const"), ssa(y,"Const")
	}

	var i interface{}      //@ ssa(i,"Const") // nil interface
	i = 1                  //@ ssa(i,"MakeInterface")
	switch i := i.(type) { //@ ssa(i,"MakeInterface"), ssa(i,"MakeInterface")
	case int:
		println(i) //@ ssa(i,"Extract")
	}

	ch := make(chan int) //@ ssa(ch,"MakeChan")
	select {
	case x := <-ch: //@ ssa(x,"UnOp") /*receive*/, ssa(ch,"MakeChan")
		_ = x //@ ssa(x,"UnOp")
	}

	// .Op is an inter-package FieldVal-selection.
	var err os.PathError //@ ssa(err,"&Alloc")
	_ = err.Op           //@ ssa(err,"&Alloc"), ssa(Op,"&FieldAddr")
	_ = &err.Op          //@ ssa(err,"&Alloc"), ssa(Op,"&FieldAddr")

	// Exercise corner-cases of lvalues vs rvalues.
	// (Guessing IsAddr from the 'pointerness' won't cut it here.)
	type N *N
	var n N    //@ ssa(n,"Const")
	n1 := n    //@ ssa(n1,"Const"), ssa(n,"Const")
	n2 := &n1  //@ ssa(n2,"Alloc"), ssa(n1,"&Alloc")
	n3 := *n2  //@ ssa(n3,"UnOp"), ssa(n2,"Alloc")
	n4 := **n3 //@ ssa(n4,"UnOp"), ssa(n3,"UnOp")
	_ = n4     //@ ssa(n4,"UnOp")
}


================================================
FILE: go/ssa/testdata/src/README.txt
================================================
These files are present to test building ssa on go files that use signatures from standard library packages.

Only the exported members used by the tests are needed.

Providing these decreases testing time ~10x (90s -> 8s) compared to building the standard library packages form source during tests.

================================================
FILE: go/ssa/testdata/src/bytes/bytes.go
================================================
package bytes

func Compare(a, b []byte) int


================================================
FILE: go/ssa/testdata/src/context/context.go
================================================
package context

type Context interface {
	Done() <-chan struct{}
}

func Background() Context


================================================
FILE: go/ssa/testdata/src/encoding/encoding.go
================================================
package encoding

type BinaryMarshaler interface {
	MarshalBinary() (data []byte, err error)
}

type BinaryUnmarshaler interface {
	UnmarshalBinary(data []byte) error
}


================================================
FILE: go/ssa/testdata/src/encoding/json/json.go
================================================
package json

func Marshal(v any) ([]byte, error)
func Unmarshal(data []byte, v any) error


================================================
FILE: go/ssa/testdata/src/encoding/xml/xml.go
================================================
package xml

func Marshal(v any) ([]byte, error)
func Unmarshal(data []byte, v any) error


================================================
FILE: go/ssa/testdata/src/errors/errors.go
================================================
package errors

func New(text string) error


================================================
FILE: go/ssa/testdata/src/fmt/fmt.go
================================================
package fmt

func Sprint(args ...interface{}) string
func Sprintln(args ...interface{}) string
func Sprintf(format string, args ...interface{}) string

func Print(args ...interface{}) (int, error)
func Println(args ...interface{})
func Printf(format string, args ...interface{}) (int, error)

func Errorf(format string, args ...interface{}) error


================================================
FILE: go/ssa/testdata/src/io/io.go
================================================
package io

import "errors"

var EOF = errors.New("EOF")


================================================
FILE: go/ssa/testdata/src/log/log.go
================================================
package log

func Println(v ...interface{})
func Fatalln(v ...interface{})
func Fatalf(format string, v ...any)


================================================
FILE: go/ssa/testdata/src/math/math.go
================================================
package math

func NaN() float64

func Inf(int) float64

func IsNaN(float64) bool

func Float64bits(float64) uint64

func Signbit(x float64) bool

func Sqrt(x float64) float64

func Sin(x float64) float64


================================================
FILE: go/ssa/testdata/src/os/os.go
================================================
package os

func Getenv(string) string

func Exit(int)


================================================
FILE: go/ssa/testdata/src/reflect/reflect.go
================================================
package reflect

type Type interface {
	Elem() Type
	Kind() Kind
	String() string
}

type Value struct{}

func (Value) String() string
func (Value) Elem() Value
func (Value) Field(int) Value
func (Value) Index(i int) Value
func (Value) Int() int64
func (Value) Interface() interface{}
func (Value) IsNil() bool
func (Value) IsValid() bool
func (Value) Kind() Kind
func (Value) Len() int
func (Value) MapIndex(Value) Value
func (Value) MapKeys() []Value
func (Value) NumField() int
func (Value) Pointer() uintptr
func (Value) SetInt(int64)
func (Value) Type() Type

func SliceOf(Type) Type
func TypeOf(interface{}) Type
func ValueOf(interface{}) Value

type Kind uint

const (
	Invalid Kind = iota
	Int
	Pointer
)

func DeepEqual(x, y interface{}) bool


================================================
FILE: go/ssa/testdata/src/runtime/runtime.go
================================================
package runtime

func GC()

func SetFinalizer(obj, finalizer any)

func Caller(skip int) (pc uintptr, file string, line int, ok bool)


================================================
FILE: go/ssa/testdata/src/sort/sort.go
================================================
package sort

func Strings(x []string)
func Ints(x []int)
func Float64s(x []float64)

func Sort(data Interface)

type Interface interface {
	Len() int
	Less(i, j int) bool
	Swap(i, j int)
}


================================================
FILE: go/ssa/testdata/src/strconv/strconv.go
================================================
package strconv

func Itoa(i int) string
func Atoi(s string) (int, error)

func FormatFloat(float64, byte, int, int) string


================================================
FILE: go/ssa/testdata/src/strings/strings.go
================================================
package strings

func Replace(s, old, new string, n int) string
func Index(haystack, needle string) int
func Contains(haystack, needle string) bool
func HasPrefix(s, prefix string) bool
func EqualFold(s, t string) bool
func ToLower(s string) string

type Builder struct{}

func (b *Builder) WriteString(s string) (int, error)
func (b *Builder) String() string


================================================
FILE: go/ssa/testdata/src/sync/atomic/atomic.go
================================================
package atomic

import "unsafe"

func LoadPointer(addr *unsafe.Pointer) (val unsafe.Pointer)


================================================
FILE: go/ssa/testdata/src/sync/sync.go
================================================
package sync

type Mutex struct{}

func (m *Mutex) Lock()
func (m *Mutex) Unlock()

type WaitGroup struct{}

func (wg *WaitGroup) Add(delta int)
func (wg *WaitGroup) Done()
func (wg *WaitGroup) Wait()


================================================
FILE: go/ssa/testdata/src/time/time.go
================================================
package time

type Duration int64

func Sleep(Duration)

func NewTimer(d Duration) *Timer

type Timer struct {
	C <-chan Time
}

func (t *Timer) Stop() bool

type Time struct{}

func After(d Duration) <-chan Time

const (
	Nanosecond Duration = iota // Specific values do not matter here.
	Second
	Minute
	Hour
)


================================================
FILE: go/ssa/testdata/src/unsafe/unsafe.go
================================================
package unsafe

// Empty unsafe package helps other packages load.
// TODO(taking): determine why.


================================================
FILE: go/ssa/testdata/structconv.go
================================================
// This file is the input to TestValueForExprStructConv in identical_test.go,
// which uses the same framework as TestValueForExpr does in source_test.go.
//
// In Go 1.8, struct conversions are permitted even when the struct types have
// different tags. This wasn't permitted in earlier versions of Go, so this file
// exists separately from valueforexpr.go to just test this behavior in Go 1.8
// and later.

package main

type t1 struct {
	x int
}
type t2 struct {
	x int `tag`
}

func main() {
	var tv1 t1
	var tv2 t2 = /*@ChangeType*/ (t2(tv1))
	_ = tv2
}


================================================
FILE: go/ssa/testdata/valueforexpr.go
================================================
package main

// This file is the input to TestValueForExpr in source_test.go, which
// ensures that each expression e immediately following a /*@kind*/(x)
// annotation, when passed to Function.ValueForExpr(e), returns a
// non-nil Value of the same type as e and of kind 'kind'.

func f(spilled, unspilled int) {
	_ = /*@UnOp*/ (spilled)
	_ = /*@Parameter*/ (unspilled)
	_ = /*@nil*/ (1 + 2) // (constant)
	i := 0

	f := func() (int, int) { return 0, 0 }

	/*@Call*/
	(print( /*@BinOp*/ (i + 1)))
	_, _ = /*@Call*/ (f())
	ch := /*@MakeChan*/ (make(chan int))
	/*@UnOp*/ (<-ch)
	x := /*@UnOp*/ (<-ch)
	_ = x
	select {
	case /*@Extract*/ (<-ch):
	case x := /*@Extract*/ (<-ch):
		_ = x
	}
	defer /*@Function*/ (func() {
	})()
	go /*@Function*/ (func() {
	})()
	y := 0
	if true && /*@BinOp*/ (bool(y > 0)) {
		y = 1
	}
	_ = /*@Phi*/ (y)
	map1 := /*@MakeMap*/ (make(map[string]string))
	_ = map1
	_ = /*@Slice*/ (make([]int, 0))
	_ = /*@MakeClosure*/ (func() { print(spilled) })

	sl := []int{}
	_ = /*@Slice*/ (sl[:0])

	_ = /*@nil*/ (new(int)) // optimized away
	tmp := /*@Alloc*/ (new(int))
	_ = tmp
	var iface interface{}
	_ = /*@TypeAssert*/ (iface.(int))
	_ = /*@UnOp*/ (sl[0])
	_ = /*@IndexAddr*/ (&sl[0])
	_ = /*@Index*/ ([2]int{}[0])
	var p *int
	_ = /*@UnOp*/ (*p)

	_ = /*@UnOp*/ (global)
	/*@UnOp*/ (global)[""] = ""
	/*@Global*/ (global) = map[string]string{}

	var local t
	/*UnOp*/ (local.x) = 1

	// Exercise corner-cases of lvalues vs rvalues.
	type N *N
	var n N
	/*@UnOp*/ (n) = /*@UnOp*/ (n)
	/*@ChangeType*/ (n) = /*@Alloc*/ (&n)
	/*@UnOp*/ (n) = /*@UnOp*/ (*n)
	/*@UnOp*/ (n) = /*@UnOp*/ (**n)
}

func complit() {
	// Composite literals.
	// We get different results for
	// - composite literal as value (e.g. operand to print)
	// - composite literal initializer for addressable value
	// - composite literal value assigned to blank var

	// 1. Slices
	print( /*@Slice*/ ([]int{}))
	print( /*@Alloc*/ (&[]int{}))
	print(& /*@Slice*/ ([]int{}))

	sl1 := /*@Slice*/ ([]int{})
	sl2 := /*@Alloc*/ (&[]int{})
	sl3 := & /*@Slice*/ ([]int{})
	_, _, _ = sl1, sl2, sl3

	_ = /*@Slice*/ ([]int{})
	_ = /*@nil*/ (& /*@Slice*/ ([]int{})) // & optimized away
	_ = & /*@Slice*/ ([]int{})

	// 2. Arrays
	print( /*@Const*/ ([1]int{}))
	print( /*@Alloc*/ (&[1]int{}))
	print(& /*@Alloc*/ ([1]int{}))

	arr1 := /*@Const*/ ([1]int{})
	arr2 := /*@Alloc*/ (&[1]int{})
	arr3 := & /*@Alloc*/ ([1]int{})
	_, _, _ = arr1, arr2, arr3

	_ = /*@Const*/ ([1]int{})
	_ = /*@nil*/ (& /*@Const*/ ([1]int{})) // & optimized away
	_ = & /*@Const*/ ([1]int{})

	// 3. Maps
	type M map[int]int
	print( /*@MakeMap*/ (M{}))
	print( /*@Alloc*/ (&M{}))
	print(& /*@MakeMap*/ (M{}))

	m1 := /*@MakeMap*/ (M{})
	m2 := /*@Alloc*/ (&M{})
	m3 := & /*@MakeMap*/ (M{})
	_, _, _ = m1, m2, m3

	_ = /*@MakeMap*/ (M{})
	_ = /*@nil*/ (& /*@MakeMap*/ (M{})) // & optimized away
	_ = & /*@MakeMap*/ (M{})

	// 4. Structs
	print( /*@Const*/ (struct{}{}))
	print( /*@Alloc*/ (&struct{}{}))
	print(& /*@Alloc*/ (struct{}{}))

	s1 := /*@Const*/ (struct{}{})
	s2 := /*@Alloc*/ (&struct{}{})
	s3 := & /*@Alloc*/ (struct{}{})
	_, _, _ = s1, s2, s3

	_ = /*@Const*/ (struct{}{})
	_ = /*@nil*/ (& /*@Const*/ (struct{}{})) // & optimized away
	_ = & /*@Const*/ (struct{}{})
}

type t struct{ x int }

// Ensure we can locate methods of named types.
func (t) f(param int) {
	_ = /*@Parameter*/ (param)
}

// Ensure we can locate init functions.
func init() {
	m := /*@MakeMap*/ (make(map[string]string))
	_ = m
}

// Ensure we can locate variables in initializer expressions.
var global = /*@MakeMap*/ (make(map[string]string))


================================================
FILE: go/ssa/testutil_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file defines helper functions for SSA tests.

package ssa_test

import (
	"fmt"
	"go/parser"
	"go/token"
	"io/fs"
	"os"
	"testing"
	"testing/fstest"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/go/ssa/ssautil"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// goMod returns a go.mod file containing a name and a go directive
// for the major version. If major < 0, use the current go toolchain
// version.
func goMod(name string, major int) []byte {
	if major < 0 {
		major = testenv.Go1Point()
	}
	return fmt.Appendf(nil, "module %s\ngo 1.%d", name, major)
}

// overlayFS returns a simple in-memory filesystem.
func overlayFS(overlay map[string][]byte) fstest.MapFS {
	// taking: Maybe loadPackages should take an overlay instead?
	fs := make(fstest.MapFS)
	for name, data := range overlay {
		fs[name] = &fstest.MapFile{Data: data}
	}
	return fs
}

// openTxtar opens a txtar file as a filesystem.
func openTxtar(t testing.TB, file string) fs.FS {
	// TODO(taking): Move to testfiles?
	t.Helper()

	ar, err := txtar.ParseFile(file)
	if err != nil {
		t.Fatal(err)
	}

	fs, err := txtar.FS(ar)
	if err != nil {
		t.Fatal(err)
	}

	return fs
}

// loadPackages copies the files in a source file system to a unique temporary
// directory and loads packages matching the given patterns from the temporary directory.
//
// TODO(69556): Migrate loader tests to loadPackages.
func loadPackages(t testing.TB, src fs.FS, patterns ...string) []*packages.Package {
	t.Helper()
	testenv.NeedsGoBuild(t) // for go/packages

	// TODO(taking): src and overlays are very similar. Overlays could have nicer paths.
	// Look into migrating src to overlays.
	dir := testfiles.CopyToTmp(t, src)

	cfg := &packages.Config{
		Dir: dir,
		Mode: packages.NeedSyntax |
			packages.NeedTypesInfo |
			packages.NeedDeps |
			packages.NeedName |
			packages.NeedFiles |
			packages.NeedImports |
			packages.NeedCompiledGoFiles |
			packages.NeedTypes,
		Env: append(os.Environ(),
			"GO111MODULES=on",
			"GOPATH=",
			"GOWORK=off",
			"GOPROXY=off"),
	}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		t.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		t.Fatal("there were errors")
	}
	return pkgs
}

// buildPackage builds the content of a go file into:
// * a module with the same name as the package at the current go version,
// * loads the *package.Package,
// * checks that (*packages.Packages).Syntax contains one file,
// * builds the *ssa.Package (and not its dependencies), and
// * returns the built *ssa.Package and the loaded packages.Package.
//
// TODO(adonovan): factor with similar loadFile (2x) in cha/cha_test.go and vta/helpers_test.go.
func buildPackage(t testing.TB, content string, mode ssa.BuilderMode) (*ssa.Package, *packages.Package) {
	name := parsePackageClause(t, content)

	fs := overlayFS(map[string][]byte{
		"go.mod":   goMod(name, -1),
		"input.go": []byte(content),
	})
	ppkgs := loadPackages(t, fs, name)
	if len(ppkgs) != 1 {
		t.Fatalf("Expected to load 1 package from pattern %q. got %d", name, len(ppkgs))
	}
	ppkg := ppkgs[0]

	if len(ppkg.Syntax) != 1 {
		t.Fatalf("Expected 1 file in package %q. got %d", ppkg, len(ppkg.Syntax))
	}

	prog, _ := ssautil.Packages(ppkgs, mode)

	ssapkg := prog.Package(ppkg.Types)
	if ssapkg == nil {
		t.Fatalf("Failed to find ssa package for %q", ppkg.Types)
	}
	ssapkg.Build()

	return ssapkg, ppkg
}

// parsePackageClause is a test helper to extract the package name from a string
// containing the content of a go file.
func parsePackageClause(t testing.TB, content string) string {
	f, err := parser.ParseFile(token.NewFileSet(), "", content, parser.PackageClauseOnly)
	if err != nil {
		t.Fatalf("parsing the file %q failed with error: %s", content, err)
	}
	return f.Name.Name
}


================================================
FILE: go/ssa/typeset.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

import (
	"go/types"

	"golang.org/x/tools/internal/typeparams"
)

// Utilities for dealing with type sets.

const debug = false

// typeset is an iterator over the (type/underlying type) pairs of the
// specific type terms of the type set implied by t.
// If t is a type parameter, the implied type set is the type set of t's constraint.
// In that case, if there are no specific terms, typeset calls yield with (nil, nil).
// If t is not a type parameter, the implied type set consists of just t.
// In any case, typeset is guaranteed to call yield at least once.
func typeset(typ types.Type, yield func(t, u types.Type) bool) {
	switch typ := types.Unalias(typ).(type) {
	case *types.TypeParam, *types.Interface:
		terms := termListOf(typ)
		if len(terms) == 0 {
			yield(nil, nil)
			return
		}
		for _, term := range terms {
			u := types.Unalias(term.Type())
			if !term.Tilde() {
				u = u.Underlying()
			}
			if debug {
				assert(types.Identical(u, u.Underlying()), "Unalias(x) == under(x) for ~x terms")
			}
			if !yield(term.Type(), u) {
				break
			}
		}
		return
	default:
		yield(typ, typ.Underlying())
	}
}

// termListOf returns the type set of typ as a normalized term set. Returns an empty set on an error.
func termListOf(typ types.Type) []*types.Term {
	terms, err := typeparams.NormalTerms(typ)
	if err != nil {
		return nil
	}
	return terms
}

// typeSetIsEmpty returns true if a typeset is empty.
func typeSetIsEmpty(typ types.Type) bool {
	var empty bool
	typeset(typ, func(t, _ types.Type) bool {
		empty = t == nil
		return false
	})
	return empty
}

// isBytestring returns true if T has the same terms as interface{[]byte | string}.
// These act like a core type for some operations: slice expressions, append and copy.
//
// See https://go.dev/ref/spec#Core_types for the details on bytestring.
func isBytestring(T types.Type) bool {
	U := T.Underlying()
	if _, ok := U.(*types.Interface); !ok {
		return false
	}

	hasBytes, hasString := false, false
	ok := underIs(U, func(t types.Type) bool {
		switch {
		case isString(t):
			hasString = true
			return true
		case isByteSlice(t):
			hasBytes = true
			return true
		default:
			return false
		}
	})
	return ok && hasBytes && hasString
}

// underIs calls f with the underlying types of the type terms
// of the type set of typ and reports whether all calls to f returned true.
// If there are no specific terms, underIs returns the result of f(nil).
func underIs(typ types.Type, f func(types.Type) bool) bool {
	var ok bool
	typeset(typ, func(t, u types.Type) bool {
		ok = f(u)
		return ok
	})
	return ok
}

// indexType returns the element type and index mode of a IndexExpr over a type.
// It returns an invalid mode if the type is not indexable; this should never occur in a well-typed program.
func indexType(typ types.Type) (types.Type, indexMode) {
	switch U := typ.Underlying().(type) {
	case *types.Array:
		return U.Elem(), ixArrVar
	case *types.Pointer:
		if arr, ok := U.Elem().Underlying().(*types.Array); ok {
			return arr.Elem(), ixVar
		}
	case *types.Slice:
		return U.Elem(), ixVar
	case *types.Map:
		return U.Elem(), ixMap
	case *types.Basic:
		return tByte, ixValue // must be a string
	case *types.Interface:
		var elem types.Type
		mode := ixInvalid
		typeset(typ, func(t, _ types.Type) bool {
			if t == nil {
				return false // empty set
			}
			e, m := indexType(t)
			if elem == nil {
				elem, mode = e, m
			}
			if debug && !types.Identical(elem, e) { // if type checked, just a sanity check
				mode = ixInvalid
				return false
			}
			// Update the mode to the most constrained address type.
			mode = mode.meet(m)
			return mode != ixInvalid
		})
		return elem, mode
	}
	return nil, ixInvalid
}

// An indexMode specifies the (addressing) mode of an index operand.
//
// Addressing mode of an index operation is based on the set of
// underlying types.
// Hasse diagram of the indexMode meet semi-lattice:
//
//	ixVar     ixMap
//	  |          |
//	ixArrVar     |
//	  |          |
//	ixValue      |
//	   \        /
//	  ixInvalid
type indexMode byte

const (
	ixInvalid indexMode = iota // index is invalid
	ixValue                    // index is a computed value (not addressable)
	ixArrVar                   // like ixVar, but index operand contains an array
	ixVar                      // index is an addressable variable
	ixMap                      // index is a map index expression (acts like a variable on lhs, commaok on rhs of an assignment)
)

// meet is the address type that is constrained by both x and y.
func (x indexMode) meet(y indexMode) indexMode {
	if (x == ixMap || y == ixMap) && x != y {
		return ixInvalid
	}
	// Use int representation and return min.
	if x < y {
		return y
	}
	return x
}


================================================
FILE: go/ssa/util.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines a number of miscellaneous utility functions.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"io"
	"os"
	"sync"
	_ "unsafe" // for go:linkname hack

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

type unit struct{}

//// Sanity checking utilities

// assert panics with the message msg if p is false.
// Avoid combining with expensive string formatting.
func assert(p bool, msg string) {
	if !p {
		panic(msg)
	}
}

//// AST utilities

// isBlankIdent returns true iff e is an Ident with name "_".
// They have no associated types.Object, and thus no type.
func isBlankIdent(e ast.Expr) bool {
	id, ok := e.(*ast.Ident)
	return ok && id.Name == "_"
}

//// Type utilities.  Some of these belong in go/types.

// isNonTypeParamInterface reports whether t is an interface type but not a type parameter.
func isNonTypeParamInterface(t types.Type) bool {
	return !typeparams.IsTypeParam(t) && types.IsInterface(t)
}

// isBasic reports whether t is a basic type.
// t is assumed to be an Underlying type (not Named or Alias).
func isBasic(t types.Type) bool {
	_, ok := t.(*types.Basic)
	return ok
}

// isString reports whether t is exactly a string type.
// t is assumed to be an Underlying type (not Named or Alias).
func isString(t types.Type) bool {
	basic, ok := t.(*types.Basic)
	return ok && basic.Info()&types.IsString != 0
}

// isByteSlice reports whether t is of the form []~bytes.
// t is assumed to be an Underlying type (not Named or Alias).
func isByteSlice(t types.Type) bool {
	if b, ok := t.(*types.Slice); ok {
		e, _ := b.Elem().Underlying().(*types.Basic)
		return e != nil && e.Kind() == types.Byte
	}
	return false
}

// isRuneSlice reports whether t is of the form []~runes.
// t is assumed to be an Underlying type (not Named or Alias).
func isRuneSlice(t types.Type) bool {
	if b, ok := t.(*types.Slice); ok {
		e, _ := b.Elem().Underlying().(*types.Basic)
		return e != nil && e.Kind() == types.Rune
	}
	return false
}

// isBasicConvTypes returns true when the type set of a type
// can be one side of a Convert operation. This is when:
// - All are basic, []byte, or []rune.
// - At least 1 is basic.
// - At most 1 is []byte or []rune.
func isBasicConvTypes(typ types.Type) bool {
	basics, cnt := 0, 0
	ok := underIs(typ, func(t types.Type) bool {
		cnt++
		if isBasic(t) {
			basics++
			return true
		}
		return isByteSlice(t) || isRuneSlice(t)
	})
	return ok && basics >= 1 && cnt-basics <= 1
}

// isPointer reports whether t's underlying type is a pointer.
func isPointer(t types.Type) bool {
	return is[*types.Pointer](t.Underlying())
}

// isPointerCore reports whether t's core type is a pointer.
//
// (Most pointer manipulation is related to receivers, in which case
// isPointer is appropriate. tecallers can use isPointer(t).
func isPointerCore(t types.Type) bool {
	return is[*types.Pointer](typeparams.CoreType(t))
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

// recvType returns the receiver type of method obj.
func recvType(obj *types.Func) types.Type {
	return obj.Signature().Recv().Type()
}

// fieldOf returns the index'th field of the (core type of) a struct type;
// otherwise returns nil.
func fieldOf(typ types.Type, index int) *types.Var {
	if st, ok := typeparams.CoreType(typ).(*types.Struct); ok {
		if 0 <= index && index < st.NumFields() {
			return st.Field(index)
		}
	}
	return nil
}

// isUntyped reports whether typ is the type of an untyped constant.
func isUntyped(typ types.Type) bool {
	// No Underlying/Unalias: untyped constant types cannot be Named or Alias.
	b, ok := typ.(*types.Basic)
	return ok && b.Info()&types.IsUntyped != 0
}

// declaredWithin reports whether an object is declared within a function.
//
// obj must not be a method or a field.
func declaredWithin(obj types.Object, fn *types.Func) bool {
	if obj.Pos() != token.NoPos {
		return fn.Scope().Contains(obj.Pos()) // trust the positions if they exist.
	}
	if fn.Pkg() != obj.Pkg() {
		return false // fast path for different packages
	}

	// Traverse Parent() scopes for fn.Scope().
	for p := obj.Parent(); p != nil; p = p.Parent() {
		if p == fn.Scope() {
			return true
		}
	}
	return false
}

// logStack prints the formatted "start" message to stderr and
// returns a closure that prints the corresponding "end" message.
// Call using 'defer logStack(...)()' to show builder stack on panic.
// Don't forget trailing parens!
func logStack(format string, args ...any) func() {
	msg := fmt.Sprintf(format, args...)
	io.WriteString(os.Stderr, msg)
	io.WriteString(os.Stderr, "\n")
	return func() {
		io.WriteString(os.Stderr, msg)
		io.WriteString(os.Stderr, " end\n")
	}
}

// newVar creates a 'var' for use in a types.Tuple.
func newVar(name string, typ types.Type) *types.Var {
	return types.NewParam(token.NoPos, nil, name, typ)
}

// anonVar creates an anonymous 'var' for use in a types.Tuple.
func anonVar(typ types.Type) *types.Var {
	return newVar("", typ)
}

var lenResults = types.NewTuple(anonVar(tInt))

// makeLen returns the len builtin specialized to type func(T)int.
func makeLen(T types.Type) *Builtin {
	lenParams := types.NewTuple(anonVar(T))
	return &Builtin{
		name: "len",
		sig:  types.NewSignatureType(nil, nil, nil, lenParams, lenResults, false),
	}
}

// receiverTypeArgs returns the type arguments to a method's receiver.
// Returns an empty list if the receiver does not have type arguments.
func receiverTypeArgs(method *types.Func) []types.Type {
	recv := method.Signature().Recv()
	_, named := typesinternal.ReceiverNamed(recv)
	if named == nil {
		return nil // recv is anonymous struct/interface
	}
	ts := named.TypeArgs()
	if ts.Len() == 0 {
		return nil
	}
	targs := make([]types.Type, ts.Len())
	for i := 0; i < ts.Len(); i++ {
		targs[i] = ts.At(i)
	}
	return targs
}

// recvAsFirstArg takes a method signature and returns a function
// signature with receiver as the first parameter.
func recvAsFirstArg(sig *types.Signature) *types.Signature {
	params := make([]*types.Var, 0, 1+sig.Params().Len())
	params = append(params, sig.Recv())
	for v := range sig.Params().Variables() {
		params = append(params, v)
	}
	return types.NewSignatureType(nil, nil, nil, types.NewTuple(params...), sig.Results(), sig.Variadic())
}

// instance returns whether an expression is a simple or qualified identifier
// that is a generic instantiation.
func instance(info *types.Info, expr ast.Expr) bool {
	// Compare the logic here against go/types.instantiatedIdent,
	// which also handles  *IndexExpr and *IndexListExpr.
	var id *ast.Ident
	switch x := expr.(type) {
	case *ast.Ident:
		id = x
	case *ast.SelectorExpr:
		id = x.Sel
	default:
		return false
	}
	_, ok := info.Instances[id]
	return ok
}

// instanceArgs returns the Instance[id].TypeArgs as a slice.
func instanceArgs(info *types.Info, id *ast.Ident) []types.Type {
	targList := info.Instances[id].TypeArgs
	if targList == nil {
		return nil
	}

	targs := make([]types.Type, targList.Len())
	for i, n := 0, targList.Len(); i < n; i++ {
		targs[i] = targList.At(i)
	}
	return targs
}

// Mapping of a type T to a canonical instance C s.t. types.Identical(T, C).
// Thread-safe.
type canonizer struct {
	mu    sync.Mutex
	types typeutil.Map // map from type to a canonical instance
	lists typeListMap  // map from a list of types to a canonical instance
}

func newCanonizer() *canonizer {
	c := &canonizer{}
	h := typeutil.MakeHasher()
	c.types.SetHasher(h)
	c.lists.hasher = h
	return c
}

// List returns a canonical representative of a list of types.
// Representative of the empty list is nil.
func (c *canonizer) List(ts []types.Type) *typeList {
	if len(ts) == 0 {
		return nil
	}

	unaliasAll := func(ts []types.Type) []types.Type {
		// Is there some top level alias?
		var found bool
		for _, t := range ts {
			if _, ok := t.(*types.Alias); ok {
				found = true
				break
			}
		}
		if !found {
			return ts // no top level alias
		}

		cp := make([]types.Type, len(ts)) // copy with top level aliases removed.
		for i, t := range ts {
			cp[i] = types.Unalias(t)
		}
		return cp
	}
	l := unaliasAll(ts)

	c.mu.Lock()
	defer c.mu.Unlock()
	return c.lists.rep(l)
}

// Type returns a canonical representative of type T.
// Removes top-level aliases.
//
// For performance, reasons the canonical instance is order-dependent,
// and may contain deeply nested aliases.
func (c *canonizer) Type(T types.Type) types.Type {
	T = types.Unalias(T) // remove the top level alias.

	c.mu.Lock()
	defer c.mu.Unlock()

	if r := c.types.At(T); r != nil {
		return r.(types.Type)
	}
	c.types.Set(T, T)
	return T
}

// A type for representing a canonized list of types.
type typeList []types.Type

func (l *typeList) identical(ts []types.Type) bool {
	if l == nil {
		return len(ts) == 0
	}
	n := len(*l)
	if len(ts) != n {
		return false
	}
	for i, left := range *l {
		right := ts[i]
		if !types.Identical(left, right) {
			return false
		}
	}
	return true
}

type typeListMap struct {
	hasher  typeutil.Hasher
	buckets map[uint32][]*typeList
}

// rep returns a canonical representative of a slice of types.
func (m *typeListMap) rep(ts []types.Type) *typeList {
	if m == nil || len(ts) == 0 {
		return nil
	}

	if m.buckets == nil {
		m.buckets = make(map[uint32][]*typeList)
	}

	h := m.hash(ts)
	bucket := m.buckets[h]
	for _, l := range bucket {
		if l.identical(ts) {
			return l
		}
	}

	// not present. create a representative.
	cp := make(typeList, len(ts))
	copy(cp, ts)
	rep := &cp

	m.buckets[h] = append(bucket, rep)
	return rep
}

func (m *typeListMap) hash(ts []types.Type) uint32 {
	if m == nil {
		return 0
	}
	// Some smallish prime far away from typeutil.Hash.
	n := len(ts)
	h := uint32(13619) + 2*uint32(n)
	for i := range n {
		h += 3 * m.hasher.Hash(ts[i])
	}
	return h
}

// instantiateMethod instantiates m with targs and returns a canonical representative for this method.
func (canon *canonizer) instantiateMethod(m *types.Func, targs []types.Type, ctxt *types.Context) *types.Func {
	recv := recvType(m)
	if p, ok := types.Unalias(recv).(*types.Pointer); ok {
		recv = p.Elem()
	}
	named := types.Unalias(recv).(*types.Named)
	inst, err := types.Instantiate(ctxt, named.Origin(), targs, false)
	if err != nil {
		panic(err)
	}
	rep := canon.Type(inst)
	obj, _, _ := types.LookupFieldOrMethod(rep, true, m.Pkg(), m.Name())
	return obj.(*types.Func)
}

// Exposed to ssautil using the linkname hack.
//
//go:linkname isSyntactic golang.org/x/tools/go/ssa.isSyntactic
func isSyntactic(pkg *Package) bool { return pkg.syntax }


================================================
FILE: go/ssa/wrappers.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package ssa

// This file defines synthesis of Functions that delegate to declared
// methods; they come in three kinds:
//
// (1) wrappers: methods that wrap declared methods, performing
//     implicit pointer indirections and embedded field selections.
//
// (2) thunks: funcs that wrap declared methods.  Like wrappers,
//     thunks perform indirections and field selections. The thunk's
//     first parameter is used as the receiver for the method call.
//
// (3) bounds: funcs that wrap declared methods.  The bound's sole
//     free variable, supplied by a closure, is used as the receiver
//     for the method call.  No indirections or field selections are
//     performed since they can be done before the call.

import (
	"fmt"

	"go/token"
	"go/types"

	"golang.org/x/tools/internal/typeparams"
)

// -- wrappers -----------------------------------------------------------

// createWrapper returns a synthetic method that delegates to the
// declared method denoted by meth.Obj(), first performing any
// necessary pointer indirections or field selections implied by meth.
//
// The resulting method's receiver type is meth.Recv().
//
// This function is versatile but quite subtle!  Consider the
// following axes of variation when making changes:
//   - optional receiver indirection
//   - optional implicit field selections
//   - meth.Obj() may denote a concrete or an interface method
//   - the result may be a thunk or a wrapper.
func createWrapper(prog *Program, sel *selection) *Function {
	obj := sel.obj.(*types.Func)      // the declared function
	sig := sel.typ.(*types.Signature) // type of this wrapper

	var recv *types.Var // wrapper's receiver or thunk's params[0]
	name := obj.Name()
	var description string
	if sel.kind == types.MethodExpr {
		name += "$thunk"
		description = "thunk"
		recv = sig.Params().At(0)
	} else {
		description = "wrapper"
		recv = sig.Recv()
	}

	description = fmt.Sprintf("%s for %s", description, sel.obj)
	if prog.mode&LogSource != 0 {
		defer logStack("create %s to (%s)", description, recv.Type())()
	}
	/* method wrapper */
	return &Function{
		name:      name,
		method:    sel,
		object:    obj,
		Signature: sig,
		Synthetic: description,
		Prog:      prog,
		pos:       obj.Pos(),
		// wrappers have no syntax
		build:     (*builder).buildWrapper,
		syntax:    nil,
		info:      nil,
		goversion: "",
	}
}

// buildWrapper builds fn.Body for a method wrapper.
func (b *builder) buildWrapper(fn *Function) {
	var recv *types.Var // wrapper's receiver or thunk's params[0]
	var start int       // first regular param
	if fn.method.kind == types.MethodExpr {
		recv = fn.Signature.Params().At(0)
		start = 1
	} else {
		recv = fn.Signature.Recv()
	}

	fn.startBody()
	fn.addSpilledParam(recv)
	createParams(fn, start)

	indices := fn.method.index

	var v Value = fn.Locals[0] // spilled receiver
	if isPointer(fn.method.recv) {
		v = emitLoad(fn, v)

		// For simple indirection wrappers, perform an informative nil-check:
		// "value method (T).f called using nil *T pointer"
		if len(indices) == 1 && !isPointer(recvType(fn.object)) {
			var c Call
			c.Call.Value = &Builtin{
				name: "ssa:wrapnilchk",
				sig:  types.NewSignatureType(nil, nil, nil, types.NewTuple(anonVar(fn.method.recv), anonVar(tString), anonVar(tString)), types.NewTuple(anonVar(fn.method.recv)), false),
			}
			c.Call.Args = []Value{
				v,
				stringConst(typeparams.MustDeref(fn.method.recv).String()),
				stringConst(fn.method.obj.Name()),
			}
			c.setType(v.Type())
			v = fn.emit(&c)
		}
	}

	// Invariant: v is a pointer, either
	//   value of *A receiver param, or
	// address of  A spilled receiver.

	// We use pointer arithmetic (FieldAddr possibly followed by
	// Load) in preference to value extraction (Field possibly
	// preceded by Load).

	v = emitImplicitSelections(fn, v, indices[:len(indices)-1], token.NoPos)

	// Invariant: v is a pointer, either
	//   value of implicit *C field, or
	// address of implicit  C field.

	var c Call
	if r := recvType(fn.object); !types.IsInterface(r) { // concrete method
		if !isPointer(r) {
			v = emitLoad(fn, v)
		}
		c.Call.Value = fn.Prog.objectMethod(fn.object, b)
		c.Call.Args = append(c.Call.Args, v)
	} else {
		c.Call.Method = fn.object
		c.Call.Value = emitLoad(fn, v) // interface (possibly a typeparam)
	}
	for _, arg := range fn.Params[1:] {
		c.Call.Args = append(c.Call.Args, arg)
	}
	emitTailCall(fn, &c)
	fn.finishBody()
}

// createParams creates parameters for wrapper method fn based on its
// Signature.Params, which do not include the receiver.
// start is the index of the first regular parameter to use.
func createParams(fn *Function, start int) {
	tparams := fn.Signature.Params()
	for i, n := start, tparams.Len(); i < n; i++ {
		fn.addParamVar(tparams.At(i))
	}
}

// -- bounds -----------------------------------------------------------

// createBound returns a bound method wrapper (or "bound"), a synthetic
// function that delegates to a concrete or interface method denoted
// by obj.  The resulting function has no receiver, but has one free
// variable which will be used as the method's receiver in the
// tail-call.
//
// Use MakeClosure with such a wrapper to construct a bound method
// closure.  e.g.:
//
//	type T int          or:  type T interface { meth() }
//	func (t T) meth()
//	var t T
//	f := t.meth
//	f() // calls t.meth()
//
// f is a closure of a synthetic wrapper defined as if by:
//
//	f := func() { return t.meth() }
//
// Unlike createWrapper, createBound need perform no indirection or field
// selections because that can be done before the closure is
// constructed.
func createBound(prog *Program, obj *types.Func) *Function {
	description := fmt.Sprintf("bound method wrapper for %s", obj)
	if prog.mode&LogSource != 0 {
		defer logStack("%s", description)()
	}
	/* bound method wrapper */
	fn := &Function{
		name:      obj.Name() + "$bound",
		object:    obj,
		Signature: changeRecv(obj.Type().(*types.Signature), nil), // drop receiver
		Synthetic: description,
		Prog:      prog,
		pos:       obj.Pos(),
		// wrappers have no syntax
		build:     (*builder).buildBound,
		syntax:    nil,
		info:      nil,
		goversion: "",
	}
	fn.FreeVars = []*FreeVar{{name: "recv", typ: recvType(obj), parent: fn}} // (cyclic)
	return fn
}

// buildBound builds fn.Body for a bound method closure.
func (b *builder) buildBound(fn *Function) {
	fn.startBody()
	createParams(fn, 0)
	var c Call

	recv := fn.FreeVars[0]
	if !types.IsInterface(recvType(fn.object)) { // concrete
		c.Call.Value = fn.Prog.objectMethod(fn.object, b)
		c.Call.Args = []Value{recv}
	} else {
		c.Call.Method = fn.object
		c.Call.Value = recv // interface (possibly a typeparam)
	}
	for _, arg := range fn.Params {
		c.Call.Args = append(c.Call.Args, arg)
	}
	emitTailCall(fn, &c)
	fn.finishBody()
}

// -- thunks -----------------------------------------------------------

// createThunk returns a thunk, a synthetic function that delegates to a
// concrete or interface method denoted by sel.obj.  The resulting
// function has no receiver, but has an additional (first) regular
// parameter.
//
// Precondition: sel.kind == types.MethodExpr.
//
//	type T int          or:  type T interface { meth() }
//	func (t T) meth()
//	f := T.meth
//	var t T
//	f(t) // calls t.meth()
//
// f is a synthetic wrapper defined as if by:
//
//	f := func(t T) { return t.meth() }
func createThunk(prog *Program, sel *selection) *Function {
	if sel.kind != types.MethodExpr {
		panic(sel)
	}

	fn := createWrapper(prog, sel)
	if fn.Signature.Recv() != nil {
		panic(fn) // unexpected receiver
	}

	return fn
}

func changeRecv(s *types.Signature, recv *types.Var) *types.Signature {
	return types.NewSignatureType(recv, nil, nil, s.Params(), s.Results(), s.Variadic())
}

// A local version of *types.Selection.
// Needed for some additional control, such as creating a MethodExpr for an instantiation.
type selection struct {
	kind     types.SelectionKind
	recv     types.Type
	typ      types.Type
	obj      types.Object
	index    []int
	indirect bool
}

func toSelection(sel *types.Selection) *selection {
	return &selection{
		kind:     sel.Kind(),
		recv:     sel.Recv(),
		typ:      sel.Type(),
		obj:      sel.Obj(),
		index:    sel.Index(),
		indirect: sel.Indirect(),
	}
}

// -- instantiations --------------------------------------------------

// buildInstantiationWrapper builds the body of an instantiation
// wrapper fn. The body calls the original generic function,
// bracketed by ChangeType conversions on its arguments and results.
func (b *builder) buildInstantiationWrapper(fn *Function) {
	orig := fn.topLevelOrigin
	sig := fn.Signature

	fn.startBody()
	if sig.Recv() != nil {
		fn.addParamVar(sig.Recv())
	}
	createParams(fn, 0)

	// Create body. Add a call to origin generic function
	// and make type changes between argument and parameters,
	// as well as return values.
	var c Call
	c.Call.Value = orig
	if res := orig.Signature.Results(); res.Len() == 1 {
		c.typ = res.At(0).Type()
	} else {
		c.typ = res
	}

	// parameter of instance becomes an argument to the call
	// to the original generic function.
	argOffset := 0
	for i, arg := range fn.Params {
		var typ types.Type
		if i == 0 && sig.Recv() != nil {
			typ = orig.Signature.Recv().Type()
			argOffset = 1
		} else {
			typ = orig.Signature.Params().At(i - argOffset).Type()
		}
		c.Call.Args = append(c.Call.Args, emitTypeCoercion(fn, arg, typ))
	}

	results := fn.emit(&c)
	var ret Return
	switch res := sig.Results(); res.Len() {
	case 0:
		// no results, do nothing.
	case 1:
		ret.Results = []Value{emitTypeCoercion(fn, results, res.At(0).Type())}
	default:
		for i := 0; i < sig.Results().Len(); i++ {
			v := emitExtract(fn, results, i)
			ret.Results = append(ret.Results, emitTypeCoercion(fn, v, res.At(i).Type()))
		}
	}

	fn.emit(&ret)
	fn.currentBlock = nil

	fn.finishBody()
}


================================================
FILE: go/types/internal/play/play.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.23

// The play program is a playground for go/types: a simple web-based
// text editor into which the user can enter a Go program, select a
// region, and see type information about it.
//
// It is intended for convenient exploration and debugging of
// go/types. The command and its web interface are not officially
// supported and they may be changed arbitrarily in the future.
package main

import (
	"encoding/json"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"reflect"
	"slices"
	"strconv"
	"strings"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typeparams"
)

// TODO(adonovan):
// - show line numbers next to textarea.
// - mention this in the go/types tutorial.
// - display versions of go/types and go command.

func main() {
	http.HandleFunc("/", handleRoot)
	http.HandleFunc("/main.js", handleJS)
	http.HandleFunc("/main.css", handleCSS)
	http.HandleFunc("/select.json", handleSelectJSON)
	const addr = "localhost:9999"
	log.Printf("Listening on http://%s", addr)
	log.Fatal(http.ListenAndServe(addr, nil))
}

func handleSelectJSON(w http.ResponseWriter, req *http.Request) {
	// Parse request.
	if err := req.ParseForm(); err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	startOffset, err := strconv.Atoi(req.Form.Get("start"))
	if err != nil {
		http.Error(w, fmt.Sprintf("start: %v", err), http.StatusBadRequest)
		return
	}
	endOffset, err := strconv.Atoi(req.Form.Get("end"))
	if err != nil {
		http.Error(w, fmt.Sprintf("end: %v", err), http.StatusBadRequest)
		return
	}

	// Write Go program to temporary file.
	f, err := os.CreateTemp("", "play-*.go")
	if err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	if _, err := io.Copy(f, req.Body); err != nil {
		f.Close() // ignore error
		http.Error(w, fmt.Sprintf("can't read body: %v", err), http.StatusInternalServerError)
		return
	}
	if err := f.Close(); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer func() {
		_ = os.Remove(f.Name()) // ignore error
	}()

	// Load and type check it.
	cfg := &packages.Config{
		Fset: token.NewFileSet(),
		Mode: packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo,
		Dir:  filepath.Dir(f.Name()),
	}
	pkgs, err := packages.Load(cfg, "file="+f.Name())
	if err != nil {
		http.Error(w, fmt.Sprintf("load: %v", err), http.StatusInternalServerError)
		return
	}
	pkg := pkgs[0]

	// -- Format the response --

	out := new(strings.Builder)

	// Parse/type error information.
	if len(pkg.Errors) > 0 {
		fmt.Fprintf(out, "Errors:\n")
		for _, err := range pkg.Errors {
			fmt.Fprintf(out, "%s: %s\n", err.Pos, err.Msg)
		}
		fmt.Fprintf(out, "\n")
	}

	fset := pkg.Fset
	file := pkg.Syntax[0]
	tokFile := fset.File(file.FileStart)
	startPos := tokFile.Pos(startOffset)
	endPos := tokFile.Pos(endOffset)

	// Syntax information
	path, exact := goastutil.PathEnclosingInterval(file, startPos, endPos)
	fmt.Fprintf(out, "Path enclosing interval #%d-%d [exact=%t]:\n",
		startOffset, endOffset, exact)
	var innermostExpr ast.Expr
	for i, n := range path {
		// Show set of names defined in each scope.
		scopeNames := ""
		{
			node := n
			prefix := ""

			// A function (Func{Decl.Lit}) doesn't have a scope of its
			// own, nor does its Body: only nested BlockStmts do.
			// The type parameters, parameters, and locals are all
			// in the scope associated with the FuncType; show it.
			switch n := n.(type) {
			case *ast.FuncDecl:
				node = n.Type
				prefix = "Type."
			case *ast.FuncLit:
				node = n.Type
				prefix = "Type."
			}

			if scope := pkg.TypesInfo.Scopes[node]; scope != nil {
				scopeNames = fmt.Sprintf(" %sScope={%s}",
					prefix,
					strings.Join(scope.Names(), ", "))
			}
		}

		// TODO(adonovan): turn these into links to highlight the source.
		start, end := fset.Position(n.Pos()), fset.Position(n.End())
		fmt.Fprintf(out, "[%d] %T @ %d:%d-%d:%d (#%d-%d)%s\n",
			i, n,
			start.Line, start.Column, end.Line,
			end.Column, start.Offset, end.Offset,
			scopeNames)
		if e, ok := n.(ast.Expr); ok && innermostExpr == nil {
			innermostExpr = e
		}
	}
	// Show the Cursor.Enclosing stack too.
	// It's usually the same, but may differ in edge
	// cases (e.g. around FuncType.Func).
	curFile, _ := inspector.New([]*ast.File{file}).Root().FirstChild()
	if cur, ok := curFile.FindByPos(startPos, endPos); ok {
		fmt.Fprintf(out, "Cursor.FindByPos().Enclosing() = %v\n",
			slices.Collect(cur.Enclosing()))
	} else {
		fmt.Fprintf(out, "Cursor.FindPos() failed\n")
	}
	// And show the astutil.Select result (enclosing, leftmost & rightmost enclosed).
	if curEnclosing, curStart, curEnd, err := astutil.Select(curFile, startPos, endPos); err == nil {
		format := func(cur inspector.Cursor) string {
			return fmt.Sprintf("%T@%v", cur.Node(), fset.Position(cur.Node().Pos()))
		}
		fmt.Fprintf(out, "astutil.Select() = (%s, %s, %s)\n",
			format(curEnclosing), format(curStart), format(curEnd))
	} else {
		fmt.Fprintf(out, "astutil.Select() = %v", err)
	}
	fmt.Fprintf(out, "\n")

	// Expression type information
	if innermostExpr != nil {
		if tv, ok := pkg.TypesInfo.Types[innermostExpr]; ok {
			var modes []string
			for _, mode := range []struct {
				name      string
				condition func(types.TypeAndValue) bool
			}{
				{"IsVoid", types.TypeAndValue.IsVoid},
				{"IsType", types.TypeAndValue.IsType},
				{"IsBuiltin", types.TypeAndValue.IsBuiltin},
				{"IsValue", types.TypeAndValue.IsValue},
				{"IsNil", types.TypeAndValue.IsNil},
				{"Addressable", types.TypeAndValue.Addressable},
				{"Assignable", types.TypeAndValue.Assignable},
				{"HasOk", types.TypeAndValue.HasOk},
			} {
				if mode.condition(tv) {
					modes = append(modes, mode.name)
				}
			}
			fmt.Fprintf(out, "%T has type %v, mode %s",
				innermostExpr, tv.Type, modes)
			if tu := tv.Type.Underlying(); tu != tv.Type {
				fmt.Fprintf(out, ", underlying type %v", tu)
			}
			if tc := typeparams.CoreType(tv.Type); tc != tv.Type {
				fmt.Fprintf(out, ", core type %v", tc)
			}
			if tv.Value != nil {
				fmt.Fprintf(out, ", and constant value %v", tv.Value)
			}
		} else {
			fmt.Fprintf(out, "%T has no type", innermostExpr)
		}
		fmt.Fprintf(out, "\n\n")
	}

	// selection x.f information (if cursor is over .f)
	for _, n := range path[:min(2, len(path))] {
		if sel, ok := n.(*ast.SelectorExpr); ok {
			seln, ok := pkg.TypesInfo.Selections[sel]
			if ok {
				fmt.Fprintf(out, "Selection: %s recv=%v obj=%v type=%v indirect=%t index=%d\n\n",
					strings.Fields("FieldVal MethodVal MethodExpr")[seln.Kind()],
					seln.Recv(),
					seln.Obj(),
					seln.Type(),
					seln.Indirect(),
					seln.Index())

			} else {
				fmt.Fprintf(out, "Selector is qualified identifier.\n\n")
			}
			break
		}
	}

	// Object type information.
	switch n := path[0].(type) {
	case *ast.Ident:
		// An embedded field is both a def and a use.
		if obj, ok := pkg.TypesInfo.Defs[n]; ok {
			if obj == nil {
				fmt.Fprintf(out, "nil def") // e.g. package name, "_", type switch
			} else {
				formatObj(out, fset, "def", obj)
			}
		}
		if obj, ok := pkg.TypesInfo.Uses[n]; ok {
			formatObj(out, fset, "use", obj)
		}
	default:
		if obj, ok := pkg.TypesInfo.Implicits[n]; ok {
			formatObj(out, fset, "implicit def", obj)
		}
	}
	fmt.Fprintf(out, "\n")

	// Pretty-print of selected syntax.
	fmt.Fprintf(out, "Pretty-printed:\n")
	format.Node(out, fset, path[0])
	fmt.Fprintf(out, "\n\n")

	// Syntax debug output.
	fmt.Fprintf(out, "Syntax:\n")
	ast.Fprint(out, fset, path[0], nil) // ignore errors
	fmt.Fprintf(out, "\n\n")

	// Show inventory of all objects, including addresses to disambiguate.
	fmt.Fprintf(out, "Objects:\n")
	for curId := range curFile.Preorder((*ast.Ident)(nil)) {
		id := curId.Node().(*ast.Ident)
		if obj := pkg.TypesInfo.Defs[id]; obj != nil {
			fmt.Fprintf(out, "%s: def %v (%p)\n", fset.Position(id.Pos()), obj, obj)
		}
		if obj, ok := pkg.TypesInfo.Uses[id]; ok {
			fmt.Fprintf(out, "%s: use %v (%p)\n", fset.Position(id.Pos()), obj, obj)
		}
	}
	fmt.Fprintf(out, "\n\n")

	// Clean up the messy temp file name.
	outStr := strings.ReplaceAll(out.String(), f.Name(), "play.go")

	// Send response.
	var respJSON struct {
		Out string
	}
	respJSON.Out = outStr

	data, _ := json.Marshal(respJSON) // can't fail
	w.Write(data)                     // ignore error
}

func formatObj(out *strings.Builder, fset *token.FileSet, ref string, obj types.Object) {
	// e.g. *types.Func -> "func"
	kind := strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))

	// Show origin of generics, and refine kind.
	var origin types.Object
	switch obj := obj.(type) {
	case *types.Var:
		if obj.IsField() {
			kind = "field"
		}
		origin = obj.Origin()

	case *types.Func:
		if recv := obj.Signature().Recv(); recv != nil {
			kind = fmt.Sprintf("method (with recv %v)", recv.Type())
		}
		origin = obj.Origin()

	case *types.TypeName:
		if obj.IsAlias() {
			kind = "type alias"
		}
		if named, ok := types.Unalias(obj.Type()).(*types.Named); ok {
			origin = named.Obj()
		}
	}

	// Include the pointer value to help distinguish fn and fn.Origin().
	// (Beware that every invocation creates new pointers so they are
	// only comparable within a single result page. Hence the need
	// for the inventory of objects below.)
	fmt.Fprintf(out, "%s of %s %s of type %v declared at %v (%p)",
		ref, kind, obj.Name(), obj.Type(), fset.Position(obj.Pos()), obj)
	if origin != nil && origin != obj {
		fmt.Fprintf(out, " (instantiation of %v)", origin.Type())
	}
	fmt.Fprintf(out, "\n\n")

	fmt.Fprintf(out, "Type:\n")
	describeType(out, obj.Type())
	fmt.Fprintf(out, "\n")

	// method set
	if methods := typeutil.IntuitiveMethodSet(obj.Type(), nil); len(methods) > 0 {
		fmt.Fprintf(out, "Methods:\n")
		for _, m := range methods {
			fmt.Fprintln(out, m)
		}
		fmt.Fprintf(out, "\n")
	}

	// scope tree
	fmt.Fprintf(out, "Scopes:\n")
	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
		var (
			start = fset.Position(scope.Pos())
			end   = fset.Position(scope.End())
		)
		fmt.Fprintf(out, "%d:%d-%d:%d: %s\n",
			start.Line, start.Column, end.Line, end.Column, scope)
	}
}

// describeType formats t to out in a way that makes it clear what methods to call on t to
// get at its parts.
// describeType assumes t was constructed by the type checker, so it doesn't check
// for recursion. The type checker replaces recursive alias types, which are illegal,
// with a BasicType that says as much. Other types that it constructs are recursive
// only via a name, and this function does not traverse names.
func describeType(out *strings.Builder, t types.Type) {
	depth := -1

	var ft func(string, types.Type)
	ft = func(prefix string, t types.Type) {
		depth++
		defer func() { depth-- }()

		for range depth {
			fmt.Fprint(out, ".  ")
		}

		fmt.Fprintf(out, "%s%T:", prefix, t)
		switch t := t.(type) {
		case *types.Basic:
			fmt.Fprintf(out, " Name: %q\n", t.Name())
		case *types.Pointer:
			fmt.Fprintln(out)
			ft("Elem: ", t.Elem())
		case *types.Slice:
			fmt.Fprintln(out)
			ft("Elem: ", t.Elem())
		case *types.Array:
			fmt.Fprintf(out, " Len: %d\n", t.Len())
			ft("Elem: ", t.Elem())
		case *types.Map:
			fmt.Fprintln(out)
			ft("Key:  ", t.Key())
			ft("Elem: ", t.Elem())
		case *types.Chan:
			fmt.Fprintf(out, " Dir: %s\n", chanDirs[t.Dir()])
			ft("Elem: ", t.Elem())
		case *types.Alias:
			fmt.Fprintf(out, " Name: %q\n", t.Obj().Name())
			ft("Rhs: ", t.Rhs())
		default:
			// For types we may have missed or which have too much to bother with,
			// print their string representation.
			// TODO(jba): print more about struct types (their fields) and interface and named
			// types (their methods).
			fmt.Fprintf(out, " %s\n", t)
		}
	}

	ft("", t)
}

var chanDirs = []string{
	"SendRecv",
	"SendOnly",
	"RecvOnly",
}

func handleRoot(w http.ResponseWriter, req *http.Request) { io.WriteString(w, mainHTML) }
func handleJS(w http.ResponseWriter, req *http.Request)   { io.WriteString(w, mainJS) }
func handleCSS(w http.ResponseWriter, req *http.Request)  { io.WriteString(w, mainCSS) }

// TODO(adonovan): avoid CSS reliance on quirks mode and enable strict mode (<!DOCTYPE html>).
const mainHTML = `<html>
<head>
<script src="/main.js"></script>
<link rel="stylesheet" href="/main.css"></link>
</head>
<body onload="onLoad()">
<h1>go/types playground</h1>
<p>Select an expression to see information about it.</p>
<textarea rows='25' id='src'>
package main

import "fmt"

func main() {
	fmt.Println("Hello, world!")
}
</textarea>
<div id='out'/>
</body>
</html>
`

const mainJS = `
function onSelectionChange() {
	var start = document.activeElement.selectionStart;
	var end = document.activeElement.selectionEnd;
	var req = new XMLHttpRequest();
	req.open("POST", "/select.json?start=" + start + "&end=" + end, false);
	req.send(document.activeElement.value);
	var resp = JSON.parse(req.responseText);
	document.getElementById('out').innerText = resp.Out;
}

function onLoad() {
	document.getElementById("src").addEventListener('select', onSelectionChange)
}
`

const mainCSS = `
textarea { width: 6in; }
body { color: gray; }
div#out { font-family: monospace; font-size: 80%; }
`


================================================
FILE: go/types/objectpath/objectpath.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package objectpath defines a naming scheme for types.Objects
// (that is, named entities in Go programs) relative to their enclosing
// package.
//
// Type-checker objects are canonical, so they are usually identified by
// their address in memory (a pointer), but a pointer has meaning only
// within one address space. By contrast, objectpath names allow the
// identity of an object to be sent from one program to another,
// establishing a correspondence between types.Object variables that are
// distinct but logically equivalent.
//
// A single object may have multiple paths. In this example,
//
//	type A struct{ X int }
//	type B A
//
// the field X has two paths due to its membership of both A and B.
// The For(obj) function always returns one of these paths, arbitrarily
// but consistently.
package objectpath

import (
	"fmt"
	"go/types"
	"strconv"
	"strings"

	"golang.org/x/tools/internal/typesinternal"
)

// TODO(adonovan): think about generic aliases.

// A Path is an opaque name that identifies a types.Object
// relative to its package. Conceptually, the name consists of a
// sequence of destructuring operations applied to the package scope
// to obtain the original object.
// The name does not include the package itself.
type Path string

// Encoding
//
// An object path is a textual and (with training) human-readable encoding
// of a sequence of destructuring operators, starting from a types.Package.
// The sequences represent a path through the package/object/type graph.
// We classify these operators by their type:
//
//	PO package->object	Package.Scope.Lookup
//	OT  object->type 	Object.Type
//	TT    type->type 	Type.{Elem,Key,{,{,Recv}Type}Params,Results,Underlying,Rhs} [EKPRUTrCa]
//	TO   type->object	Type.{At,Field,Method,Obj} [AFMO]
//
// All valid paths start with a package and end at an object
// and thus may be defined by the regular language:
//
//	objectpath = PO (OT TT* TO)*
//
// The concrete encoding follows directly:
//   - The only PO operator is Package.Scope.Lookup, which requires an identifier.
//   - The only OT operator is Object.Type,
//     which we encode as '.' because dot cannot appear in an identifier.
//   - The TT operators are encoded as [EKPRUTrCa];
//     two of these ({,Recv}TypeParams) require an integer operand,
//     which is encoded as a string of decimal digits.
//   - The TO operators are encoded as [AFMO];
//     three of these (At,Field,Method) require an integer operand,
//     which is encoded as a string of decimal digits.
//     These indices are stable across different representations
//     of the same package, even source and export data.
//     The indices used are implementation specific and may not correspond to
//     the argument to the go/types function.
//
// In the example below,
//
//	package p
//
//	type T interface {
//		f() (a string, b struct{ X int })
//	}
//
// field X has the path "T.UM0.RA1.F0",
// representing the following sequence of operations:
//
//	p.Lookup("T")					T
//	.Type().Underlying().Method(0).			f
//	.Type().Results().At(1)				b
//	.Type().Field(0)					X
//
// The encoding is not maximally compact---every R or P is
// followed by an A, for example---but this simplifies the
// encoder and decoder.
const (
	// object->type operators
	opType = '.' // .Type()		  (Object)

	// type->type operators
	opElem          = 'E' // .Elem()		(Pointer, Slice, Array, Chan, Map)
	opKey           = 'K' // .Key()			(Map)
	opParams        = 'P' // .Params()		(Signature)
	opResults       = 'R' // .Results()		(Signature)
	opUnderlying    = 'U' // .Underlying()		(Named)
	opTypeParam     = 'T' // .TypeParams.At(i)	(Named, Signature)
	opRecvTypeParam = 'r' // .RecvTypeParams.At(i)	(Signature)
	opConstraint    = 'C' // .Constraint()		(TypeParam)
	opRhs           = 'a' // .Rhs()			(Alias)

	// type->object operators
	opAt     = 'A' // .At(i)	(Tuple)
	opField  = 'F' // .Field(i)	(Struct)
	opMethod = 'M' // .Method(i)	(Named or Interface; not Struct: "promoted" names are ignored)
	opObj    = 'O' // .Obj()	(Named, TypeParam)
)

// For is equivalent to new(Encoder).For(obj).
//
// It may be more efficient to reuse a single Encoder across several calls.
func For(obj types.Object) (Path, error) {
	return new(Encoder).For(obj)
}

// An Encoder amortizes the cost of encoding the paths of multiple objects.
// The zero value of an Encoder is ready to use.
type Encoder struct {
	scopeMemo map[*types.Scope][]types.Object // memoization of scopeObjects
}

// For returns the path to an object relative to its package,
// or an error if the object is not accessible from the package's Scope.
//
// The For function guarantees to return a path only for the following objects:
// - package-level types
// - exported package-level non-types
// - methods
// - parameter and result variables
// - struct fields
// These objects are sufficient to define the API of their package.
// The objects described by a package's export data are drawn from this set.
//
// The set of objects accessible from a package's Scope depends on
// whether the package was produced by type-checking syntax, or
// reading export data; the latter may have a smaller Scope since
// export data trims objects that are not reachable from an exported
// declaration. For example, the For function will return a path for
// an exported method of an unexported type that is not reachable
// from any public declaration; this path will cause the Object
// function to fail if called on a package loaded from export data.
// TODO(adonovan): is this a bug or feature? Should this package
// compute accessibility in the same way?
//
// For does not return a path for predeclared names, imported package
// names, local names, and unexported package-level names (except
// types).
//
// Example: given this definition,
//
//	package p
//
//	type T interface {
//		f() (a string, b struct{ X int })
//	}
//
// For(X) would return a path that denotes the following sequence of operations:
//
//	p.Scope().Lookup("T")				(TypeName T)
//	.Type().Underlying().Method(0).			(method Func f)
//	.Type().Results().At(1)				(field Var b)
//	.Type().Field(0)					(field Var X)
//
// where p is the package (*types.Package) to which X belongs.
func (enc *Encoder) For(obj types.Object) (Path, error) {
	pkg := obj.Pkg()

	// This table lists the cases of interest.
	//
	// Object				Action
	// ------                               ------
	// nil					reject
	// builtin				reject
	// pkgname				reject
	// label				reject
	// var
	//    package-level			accept
	//    func param/result			accept
	//    local				reject
	//    struct field			accept
	// const
	//    package-level			accept
	//    local				reject
	// func
	//    package-level			accept
	//    init functions			reject
	//    concrete method			accept
	//    interface method			accept
	// type
	//    package-level			accept
	//    local				reject
	//
	// The only accessible package-level objects are members of pkg itself.
	//
	// The cases are handled in four steps:
	//
	// 1. reject nil and builtin
	// 2. accept package-level objects
	// 3. reject obviously invalid objects
	// 4. search the API for the path to the param/result/field/method.

	// 1. reference to nil or builtin?
	if pkg == nil {
		return "", fmt.Errorf("predeclared %s has no path", obj)
	}
	scope := pkg.Scope()

	// 2. package-level object?
	if scope.Lookup(obj.Name()) == obj {
		// Only exported objects (and non-exported types) have a path.
		// Non-exported types may be referenced by other objects.
		if _, ok := obj.(*types.TypeName); !ok && !obj.Exported() {
			return "", fmt.Errorf("no path for non-exported %v", obj)
		}
		return Path(obj.Name()), nil
	}

	// 3. Not a package-level object.
	//    Reject obviously non-viable cases.
	switch obj := obj.(type) {
	case *types.TypeName:
		if _, ok := types.Unalias(obj.Type()).(*types.TypeParam); !ok {
			// With the exception of type parameters, only package-level type names
			// have a path.
			return "", fmt.Errorf("no path for %v", obj)
		}
	case *types.Const, // Only package-level constants have a path.
		*types.Label,   // Labels are function-local.
		*types.PkgName: // PkgNames are file-local.
		return "", fmt.Errorf("no path for %v", obj)

	case *types.Var:
		// Could be:
		// - a field (obj.IsField())
		// - a func parameter or result
		// - a local var.
		// Sadly there is no way to distinguish
		// a param/result from a local
		// so we must proceed to the find.

	case *types.Func:
		// A func, if not package-level, must be a method.
		if recv := obj.Signature().Recv(); recv == nil {
			return "", fmt.Errorf("func is not a method: %v", obj)
		}

		if path, ok := enc.concreteMethod(obj); ok {
			// Fast path for concrete methods that avoids looping over scope.
			return path, nil
		}

	default:
		panic(obj)
	}

	// 4. Search the API for the path to the var (field/param/result) or method.

	// First inspect package-level named types.
	// In the presence of path aliases, these give
	// the best paths because non-types may
	// refer to types, but not the reverse.
	empty := make([]byte, 0, 48) // initial space
	objs := enc.scopeObjects(scope)
	for _, o := range objs {
		tname, ok := o.(*types.TypeName)
		if !ok {
			continue // handle non-types in second pass
		}

		path := append(empty, o.Name()...)
		path = append(path, opType)

		T := o.Type()
		if alias, ok := T.(*types.Alias); ok {
			if r := findTypeParam(obj, alias.TypeParams(), path, opTypeParam); r != nil {
				return Path(r), nil
			}
			if r := find(obj, alias.Rhs(), append(path, opRhs)); r != nil {
				return Path(r), nil
			}

		} else if tname.IsAlias() {
			// legacy alias
			if r := find(obj, T, path); r != nil {
				return Path(r), nil
			}

		} else if named, ok := T.(*types.Named); ok {
			// defined (named) type
			if r := findTypeParam(obj, named.TypeParams(), path, opTypeParam); r != nil {
				return Path(r), nil
			}
			if r := find(obj, named.Underlying(), append(path, opUnderlying)); r != nil {
				return Path(r), nil
			}
		}
	}

	// Then inspect everything else:
	// non-types, and declared methods of defined types.
	for _, o := range objs {
		path := append(empty, o.Name()...)
		if _, ok := o.(*types.TypeName); !ok {
			if o.Exported() {
				// exported non-type (const, var, func)
				if r := find(obj, o.Type(), append(path, opType)); r != nil {
					return Path(r), nil
				}
			}
			continue
		}

		// Inspect declared methods of defined types.
		if T, ok := types.Unalias(o.Type()).(*types.Named); ok {
			path = append(path, opType)
			// The method index here is always with respect
			// to the underlying go/types data structures,
			// which ultimately derives from source order
			// and must be preserved by export data.
			for i := 0; i < T.NumMethods(); i++ {
				m := T.Method(i)
				path2 := appendOpArg(path, opMethod, i)
				if m == obj {
					return Path(path2), nil // found declared method
				}
				if r := find(obj, m.Type(), append(path2, opType)); r != nil {
					return Path(r), nil
				}
			}
		}
	}

	return "", fmt.Errorf("can't find path for %v in %s", obj, pkg.Path())
}

func appendOpArg(path []byte, op byte, arg int) []byte {
	path = append(path, op)
	path = strconv.AppendInt(path, int64(arg), 10)
	return path
}

// concreteMethod returns the path for meth, which must have a non-nil receiver.
// The second return value indicates success and may be false if the method is
// an interface method or if it is an instantiated method.
//
// This function is just an optimization that avoids the general scope walking
// approach. You are expected to fall back to the general approach if this
// function fails.
func (enc *Encoder) concreteMethod(meth *types.Func) (Path, bool) {
	// Concrete methods can only be declared on package-scoped named types. For
	// that reason we can skip the expensive walk over the package scope: the
	// path will always be package -> named type -> method. We can trivially get
	// the type name from the receiver, and only have to look over the type's
	// methods to find the method index.
	//
	// Methods on generic types require special consideration, however. Consider
	// the following package:
	//
	// 	L1: type S[T any] struct{}
	// 	L2: func (recv S[A]) Foo() { recv.Bar() }
	// 	L3: func (recv S[B]) Bar() { }
	// 	L4: type Alias = S[int]
	// 	L5: func _[T any]() { var s S[int]; s.Foo() }
	//
	// The receivers of methods on generic types are instantiations. L2 and L3
	// instantiate S with the type-parameters A and B, which are scoped to the
	// respective methods. L4 and L5 each instantiate S with int. Each of these
	// instantiations has its own method set, full of methods (and thus objects)
	// with receivers whose types are the respective instantiations. In other
	// words, we have
	//
	// S[A].Foo, S[A].Bar
	// S[B].Foo, S[B].Bar
	// S[int].Foo, S[int].Bar
	//
	// We may thus be trying to produce object paths for any of these objects.
	//
	// S[A].Foo and S[B].Bar are the origin methods, and their paths are S.Foo
	// and S.Bar, which are the paths that this function naturally produces.
	//
	// S[A].Bar, S[B].Foo, and both methods on S[int] are instantiations that
	// don't correspond to the origin methods. For S[int], this is significant.
	// The most precise object path for S[int].Foo, for example, is Alias.Foo,
	// not S.Foo. Our function, however, would produce S.Foo, which would
	// resolve to a different object.
	//
	// For S[A].Bar and S[B].Foo it could be argued that S.Bar and S.Foo are
	// still the correct paths, since only the origin methods have meaningful
	// paths. But this is likely only true for trivial cases and has edge cases.
	// Since this function is only an optimization, we err on the side of giving
	// up, deferring to the slower but definitely correct algorithm. Most users
	// of objectpath will only be giving us origin methods, anyway, as referring
	// to instantiated methods is usually not useful.

	if meth.Origin() != meth {
		return "", false
	}

	_, named := typesinternal.ReceiverNamed(meth.Signature().Recv())
	if named == nil {
		return "", false
	}

	if types.IsInterface(named) {
		// Named interfaces don't have to be package-scoped
		//
		// TODO(dominikh): opt: if scope.Lookup(name) == named, then we can apply this optimization to interface
		// methods, too, I think.
		return "", false
	}

	// Preallocate space for the name, opType, opMethod, and some digits.
	name := named.Obj().Name()
	path := make([]byte, 0, len(name)+8)
	path = append(path, name...)
	path = append(path, opType)

	// Method indices are w.r.t. the go/types data structures,
	// ultimately deriving from source order,
	// which is preserved by export data.
	for i := 0; i < named.NumMethods(); i++ {
		if named.Method(i) == meth {
			path = appendOpArg(path, opMethod, i)
			return Path(path), true
		}
	}

	// Due to golang/go#59944, go/types fails to associate the receiver with
	// certain methods on cgo types.
	//
	// TODO(rfindley): replace this panic once golang/go#59944 is fixed in all Go
	// versions gopls supports.
	return "", false
	// panic(fmt.Sprintf("couldn't find method %s on type %s; methods: %#v", meth, named, enc.namedMethods(named)))
}

// find finds obj within type T, returning the path to it, or nil if not found.
//
// The seen map is used to short circuit cycles through type parameters. If
// nil, it will be allocated as necessary.
//
// The seenMethods map is used internally to short circuit cycles through
// interface methods, such as occur in the following example:
//
//	type I interface { f() interface{I} }
//
// See golang/go#68046 for details.
func find(obj types.Object, T types.Type, path []byte) []byte {
	return (&finder{obj: obj}).find(T, path)
}

// finder closes over search state for a call to find.
type finder struct {
	obj             types.Object             // the sought object
	seenTParamNames map[*types.TypeName]bool // for cycle breaking through type parameters
	seenMethods     map[*types.Func]bool     // for cycle breaking through recursive interfaces
}

func (f *finder) find(T types.Type, path []byte) []byte {
	switch T := T.(type) {
	case *types.Alias:
		return f.find(types.Unalias(T), path)
	case *types.Basic, *types.Named:
		// Named types belonging to pkg were handled already,
		// so T must belong to another package. No path.
		return nil
	case *types.Pointer:
		return f.find(T.Elem(), append(path, opElem))
	case *types.Slice:
		return f.find(T.Elem(), append(path, opElem))
	case *types.Array:
		return f.find(T.Elem(), append(path, opElem))
	case *types.Chan:
		return f.find(T.Elem(), append(path, opElem))
	case *types.Map:
		if r := f.find(T.Key(), append(path, opKey)); r != nil {
			return r
		}
		return f.find(T.Elem(), append(path, opElem))
	case *types.Signature:
		if r := f.findTypeParam(T.RecvTypeParams(), path, opRecvTypeParam); r != nil {
			return r
		}
		if r := f.findTypeParam(T.TypeParams(), path, opTypeParam); r != nil {
			return r
		}
		if r := f.find(T.Params(), append(path, opParams)); r != nil {
			return r
		}
		return f.find(T.Results(), append(path, opResults))
	case *types.Struct:
		for i := 0; i < T.NumFields(); i++ {
			fld := T.Field(i)
			path2 := appendOpArg(path, opField, i)
			if fld == f.obj {
				return path2 // found field var
			}
			if r := f.find(fld.Type(), append(path2, opType)); r != nil {
				return r
			}
		}
		return nil
	case *types.Tuple:
		for i := 0; i < T.Len(); i++ {
			v := T.At(i)
			path2 := appendOpArg(path, opAt, i)
			if v == f.obj {
				return path2 // found param/result var
			}
			if r := f.find(v.Type(), append(path2, opType)); r != nil {
				return r
			}
		}
		return nil
	case *types.Interface:
		for i := 0; i < T.NumMethods(); i++ {
			m := T.Method(i)
			if f.seenMethods[m] {
				return nil
			}
			path2 := appendOpArg(path, opMethod, i)
			if m == f.obj {
				return path2 // found interface method
			}
			if f.seenMethods == nil {
				f.seenMethods = make(map[*types.Func]bool)
			}
			f.seenMethods[m] = true
			if r := f.find(m.Type(), append(path2, opType)); r != nil {
				return r
			}
		}
		return nil
	case *types.TypeParam:
		name := T.Obj()
		if f.seenTParamNames[name] {
			return nil
		}
		if name == f.obj {
			return append(path, opObj)
		}
		if f.seenTParamNames == nil {
			f.seenTParamNames = make(map[*types.TypeName]bool)
		}
		f.seenTParamNames[name] = true
		if r := f.find(T.Constraint(), append(path, opConstraint)); r != nil {
			return r
		}
		return nil
	}
	panic(T)
}

func findTypeParam(obj types.Object, list *types.TypeParamList, path []byte, op byte) []byte {
	return (&finder{obj: obj}).findTypeParam(list, path, op)
}

func (f *finder) findTypeParam(list *types.TypeParamList, path []byte, op byte) []byte {
	for i := 0; i < list.Len(); i++ {
		tparam := list.At(i)
		path2 := appendOpArg(path, op, i)
		if r := f.find(tparam, path2); r != nil {
			return r
		}
	}
	return nil
}

// Object returns the object denoted by path p within the package pkg.
func Object(pkg *types.Package, p Path) (types.Object, error) {
	pathstr := string(p)
	if pathstr == "" {
		return nil, fmt.Errorf("empty path")
	}

	var pkgobj, suffix string
	if dot := strings.IndexByte(pathstr, opType); dot < 0 {
		pkgobj = pathstr
	} else {
		pkgobj = pathstr[:dot]
		suffix = pathstr[dot:] // suffix starts with "."
	}

	obj := pkg.Scope().Lookup(pkgobj)
	if obj == nil {
		return nil, fmt.Errorf("package %s does not contain %q", pkg.Path(), pkgobj)
	}

	// abstraction of *types.{Pointer,Slice,Array,Chan,Map}
	type hasElem interface {
		Elem() types.Type
	}
	// abstraction of *types.{Named,Signature}
	type hasTypeParams interface {
		TypeParams() *types.TypeParamList
	}
	// abstraction of *types.{Alias,Named,TypeParam}
	type hasObj interface {
		Obj() *types.TypeName
	}

	// The loop state is the pair (t, obj),
	// exactly one of which is non-nil, initially obj.
	// All suffixes start with '.' (the only object->type operation),
	// followed by optional type->type operations,
	// then a type->object operation.
	// The cycle then repeats.
	var t types.Type
	for suffix != "" {
		code := suffix[0]
		suffix = suffix[1:]

		// Codes [AFMTr] have an integer operand.
		var index int
		switch code {
		case opAt, opField, opMethod, opTypeParam, opRecvTypeParam:
			rest := strings.TrimLeft(suffix, "0123456789")
			numerals := suffix[:len(suffix)-len(rest)]
			suffix = rest
			i, err := strconv.Atoi(numerals)
			if err != nil {
				return nil, fmt.Errorf("invalid path: bad numeric operand %q for code %q", numerals, code)
			}
			index = int(i)
		case opObj:
			// no operand
		default:
			// The suffix must end with a type->object operation.
			if suffix == "" {
				return nil, fmt.Errorf("invalid path: ends with %q, want [AFMO]", code)
			}
		}

		if code == opType {
			if t != nil {
				return nil, fmt.Errorf("invalid path: unexpected %q in type context", opType)
			}
			t = obj.Type()
			obj = nil
			continue
		}

		if t == nil {
			return nil, fmt.Errorf("invalid path: code %q in object context", code)
		}

		// Inv: t != nil, obj == nil

		t = types.Unalias(t)
		switch code {
		case opElem:
			hasElem, ok := t.(hasElem) // Pointer, Slice, Array, Chan, Map
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want pointer, slice, array, chan or map)", code, t, t)
			}
			t = hasElem.Elem()

		case opKey:
			mapType, ok := t.(*types.Map)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want map)", code, t, t)
			}
			t = mapType.Key()

		case opParams:
			sig, ok := t.(*types.Signature)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
			}
			t = sig.Params()

		case opResults:
			sig, ok := t.(*types.Signature)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
			}
			t = sig.Results()

		case opUnderlying:
			named, ok := t.(*types.Named)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named)", code, t, t)
			}
			t = named.Underlying()

		case opRhs:
			if alias, ok := t.(*types.Alias); ok {
				t = alias.Rhs()
			} else if false {
				// Now that go1.24 is assured, we should be able to
				// replace this with "if true {", but it causes objectpath
				// tests to fail. TODO(adonovan): investigate.
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want alias)", code, t, t)
			}

		case opTypeParam:
			hasTypeParams, ok := t.(hasTypeParams) // Named, Signature
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or signature)", code, t, t)
			}
			tparams := hasTypeParams.TypeParams()
			if n := tparams.Len(); index >= n {
				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
			}
			t = tparams.At(index)

		case opRecvTypeParam:
			sig, ok := t.(*types.Signature) // Signature
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want signature)", code, t, t)
			}
			rtparams := sig.RecvTypeParams()
			if n := rtparams.Len(); index >= n {
				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
			}
			t = rtparams.At(index)

		case opConstraint:
			tparam, ok := t.(*types.TypeParam)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want type parameter)", code, t, t)
			}
			t = tparam.Constraint()

		case opAt:
			tuple, ok := t.(*types.Tuple)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want tuple)", code, t, t)
			}
			if n := tuple.Len(); index >= n {
				return nil, fmt.Errorf("tuple index %d out of range [0-%d)", index, n)
			}
			obj = tuple.At(index)
			t = nil

		case opField:
			structType, ok := t.(*types.Struct)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want struct)", code, t, t)
			}
			if n := structType.NumFields(); index >= n {
				return nil, fmt.Errorf("field index %d out of range [0-%d)", index, n)
			}
			obj = structType.Field(index)
			t = nil

		case opMethod:
			switch t := t.(type) {
			case *types.Interface:
				if index >= t.NumMethods() {
					return nil, fmt.Errorf("method index %d out of range [0-%d)", index, t.NumMethods())
				}
				obj = t.Method(index) // Id-ordered

			case *types.Named:
				if index >= t.NumMethods() {
					return nil, fmt.Errorf("method index %d out of range [0-%d)", index, t.NumMethods())
				}
				obj = t.Method(index)

			default:
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want interface or named)", code, t, t)
			}
			t = nil

		case opObj:
			hasObj, ok := t.(hasObj)
			if !ok {
				return nil, fmt.Errorf("cannot apply %q to %s (got %T, want named or type param)", code, t, t)
			}
			obj = hasObj.Obj()
			t = nil

		default:
			return nil, fmt.Errorf("invalid path: unknown code %q", code)
		}
	}

	if obj == nil {
		panic(p) // path does not end in an object-valued operator
	}

	if obj.Pkg() != pkg {
		return nil, fmt.Errorf("path denotes %s, which belongs to a different package", obj)
	}

	return obj, nil // success
}

// scopeObjects is a memoization of scope objects.
// Callers must not modify the result.
func (enc *Encoder) scopeObjects(scope *types.Scope) []types.Object {
	m := enc.scopeMemo
	if m == nil {
		m = make(map[*types.Scope][]types.Object)
		enc.scopeMemo = m
	}
	objs, ok := m[scope]
	if !ok {
		names := scope.Names() // allocates and sorts
		objs = make([]types.Object, len(names))
		for i, name := range names {
			objs[i] = scope.Lookup(name)
		}
		m[scope] = objs
	}
	return objs
}


================================================
FILE: go/types/objectpath/objectpath_go118_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package objectpath_test

import (
	"go/types"
	"testing"

	"golang.org/x/tools/go/types/objectpath"
)

// TODO(adonovan): merge this back into objectpath_test.go.
func TestGenericPaths(t *testing.T) {
	const src = `
-- go.mod --
module x.io
go 1.18

-- b/b.go --
package b

const C int = 1

type T[TP0 any, TP1 interface{ M0(); M1() }] struct{}

func (T[RP0, RP1]) M() {}

type N int

func (N) M0()
func (N) M1()

type A = T[int, N]

func F[FP0 any, FP1 interface{ M() }](FP0, FP1) {}
`

	pkgmap := loadPackages(t, src, "./b")

	paths := []pathTest{
		// Good paths
		{"b", "T", "type b.T[TP0 any, TP1 interface{M0(); M1()}] struct{}", ""},
		{"b", "T.O", "type b.T[TP0 any, TP1 interface{M0(); M1()}] struct{}", ""},
		{"b", "T.M0", "func (b.T[RP0, RP1]).M()", ""},
		{"b", "T.M0.r1O", "type parameter RP1 interface{M0(); M1()}", ""},
		{"b", "T.M0.r1CM1", "func (interface).M1()", ""},
		{"b", "T.T0O", "type parameter TP0 any", ""},
		{"b", "T.T1O", "type parameter TP1 interface{M0(); M1()}", ""},
		{"b", "T.T1CM0", "func (interface).M0()", ""},
		{"b", "F.T0O", "type parameter FP0 any", ""},
		{"b", "F.T1CM0", "func (interface).M()", ""},
		// Obj of an instance is the generic declaration.
		{"b", "A.O", "type b.T[TP0 any, TP1 interface{M0(); M1()}] struct{}", ""},
		{"b", "A.M0", "func (b.T[int, b.N]).M()", ""},

		// Bad paths
		{"b", "N.C", "", "invalid path: ends with 'C', want [AFMO]"},
		{"b", "N.CO", "", "cannot apply 'C' to b.N (got *types.Named, want type parameter)"},
		{"b", "N.T", "", `invalid path: bad numeric operand "" for code 'T'`},
		{"b", "N.T0", "", "tuple index 0 out of range [0-0)"},
		{"b", "T.T2O", "", "tuple index 2 out of range [0-2)"},
		{"b", "T.T1M0", "", "cannot apply 'M' to TP1 (got *types.TypeParam, want interface or named)"},
		{"b", "C.T0", "", "cannot apply 'T' to int (got *types.Basic, want named or signature)"},
	}
	for _, test := range paths {
		if err := testPath(pkgmap, test); err != nil {
			t.Error(err)
		}
	}

	// bad objects
	for _, test := range []struct {
		obj     types.Object
		wantErr string
	}{
		{types.Universe.Lookup("any"), "predeclared type any = interface{} has no path"},
		{types.Universe.Lookup("comparable"), "predeclared type comparable interface{comparable} has no path"},
	} {
		path, err := objectpath.For(test.obj)
		if err == nil {
			t.Errorf("Object(%s) = %q, want error", test.obj, path)
			continue
		}
		if err.Error() != test.wantErr {
			t.Errorf("Object(%s) error was %q, want %q", test.obj, err, test.wantErr)
			continue
		}
	}
}

func TestGenericPaths_Issue51717(t *testing.T) {
	const src = `
-- go.mod --
module x.io
go 1.18

-- p/p.go --
package p

type S struct{}

func (_ S) M() {
	// The go vet stackoverflow crash disappears when the following line is removed
	panic("")
}

func F[WL interface{ N(item W) WL }, W any]() {
}

func main() {}
`
	pkgmap := loadPackages(t, src, "./p")

	paths := []pathTest{
		{"p", "F.T0CM0.RA0", "var  WL", ""},
		{"p", "F.T0CM0.RA0.CM0", "func (interface).N(item W) WL", ""},

		// Finding S.M0 reproduced the infinite recursion reported in #51717,
		// because F is searched before S.
		{"p", "S.M0", "func (p.S).M()", ""},
	}
	for _, test := range paths {
		if err := testPath(pkgmap, test); err != nil {
			t.Error(err)
		}
	}
}


================================================
FILE: go/types/objectpath/objectpath_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package objectpath_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"strings"
	"testing"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestPaths(t *testing.T) {
	const src = `
-- go.mod --
module x.io

-- b/b.go --
package b

import "x.io/a"

const C = a.Int(0)

func F(a, b, c int, d a.T)

type T struct{ A int; b int; a.T }

func (T) M() *interface{ f() }

type U T

type A = struct{ x int }

type unexported2 struct { z int }
type AN = unexported2 // alias of named

// type GA[T any] = T // see below

var V []*a.T

type M map[struct{x int}]struct{y int}

func unexportedFunc()
type unexportedType struct{}

func (unexportedType) F() {} // not reachable from package's public API (export data)

type S struct{t struct{x int}}
type R []struct{y int}
type Q [2]struct{z int}

-- a/a.go --
package a

type Int int

type T struct{x, y int}

type Issue68046 interface { f(x int) interface{Issue68046} }
`

	pkgmap := loadPackages(t, src, "./a", "./b")

	paths := []pathTest{
		// Good paths
		{"b", "C", "const b.C a.Int", ""},
		{"b", "F", "func b.F(a int, b int, c int, d a.T)", ""},
		{"b", "F.PA0", "var a int", ""},
		{"b", "F.PA1", "var b int", ""},
		{"b", "F.PA2", "var c int", ""},
		{"b", "F.PA3", "var d a.T", ""},
		{"b", "T", "type b.T struct{A int; b int; a.T}", ""},
		{"b", "T.O", "type b.T struct{A int; b int; a.T}", ""},
		{"b", "T.UF0", "field A int", ""},
		{"b", "T.UF1", "field b int", ""},
		{"b", "T.UF2", "field T a.T", ""},
		{"b", "U.UF2", "field T a.T", ""},          // U.U... are aliases for T.U...
		{"b", "A", "type b.A = struct{x int}", ""}, // go1.22/alias=1: "type b.A = b.A"
		{"b", "A.aF0", "field x int", ""},
		{"b", "A.F0", "field x int", ""},
		{"b", "AN", "type b.AN = b.unexported2", ""}, // go1.22/alias=1: "type b.AN = b.AN"
		{"b", "AN.UF0", "field z int", ""},
		{"b", "AN.aO", "type b.unexported2 struct{z int}", ""},
		{"b", "AN.O", "type b.unexported2 struct{z int}", ""},
		{"b", "AN.aUF0", "field z int", ""},
		{"b", "AN.UF0", "field z int", ""},
		// {"b", "GA", "type parameter b.GA = T", ""}, // TODO(adonovan): enable once GOEXPERIMENT=aliastypeparams has gone
		{"b", "V", "var b.V []*a.T", ""},
		{"b", "M", "type b.M map[struct{x int}]struct{y int}", ""},
		{"b", "M.UKF0", "field x int", ""},
		{"b", "M.UEF0", "field y int", ""},
		{"b", "T.M0", "func (b.T).M() *interface{f()}", ""}, // concrete method
		{"b", "T.M0.RA0", "var  *interface{f()}", ""},       // parameter
		{"b", "T.M0.RA0.EM0", "func (interface).f()", ""},   // interface method
		{"b", "unexportedType", "type b.unexportedType struct{}", ""},
		{"b", "unexportedType.M0", "func (b.unexportedType).F()", ""},
		{"b", "S.UF0.F0", "field x int", ""},
		{"b", "R.UEF0", "field y int", ""},
		{"b", "Q.UEF0", "field z int", ""},
		{"a", "T", "type a.T struct{x int; y int}", ""},
		{"a", "Issue68046.UM0", "func (a.Issue68046).f(x int) interface{a.Issue68046}", ""},
		{"a", "Issue68046.UM0.PA0", "var x int", ""},

		// Bad paths
		{"b", "", "", "empty path"},
		{"b", "missing", "", `package b does not contain "missing"`},
		{"b", "F.U", "", "invalid path: ends with 'U', want [AFMO]"},
		{"b", "F.PA3.O", "", "path denotes type a.T struct{x int; y int}, which belongs to a different package"},
		{"b", "F.PA!", "", `invalid path: bad numeric operand "" for code 'A'`},
		{"b", "F.PA3.UF0", "", "path denotes field x int, which belongs to a different package"},
		{"b", "F.PA3.UF5", "", "field index 5 out of range [0-2)"},
		{"b", "V.EE", "", "invalid path: ends with 'E', want [AFMO]"},
		{"b", "F..O", "", "invalid path: unexpected '.' in type context"},
		{"b", "T.OO", "", "invalid path: code 'O' in object context"},
		{"b", "T.EO", "", "cannot apply 'E' to b.T (got *types.Named, want pointer, slice, array, chan or map)"},
		{"b", "A.O", "", "cannot apply 'O' to struct{x int} (got *types.Struct, want named or type param)"},
		{"b", "A.UF0", "", "cannot apply 'U' to struct{x int} (got *types.Struct, want named)"},
		{"b", "M.UPO", "", "cannot apply 'P' to map[struct{x int}]struct{y int} (got *types.Map, want signature)"},
		{"b", "C.O", "", "path denotes type a.Int int, which belongs to a different package"},
		{"b", "T.M9", "", "method index 9 out of range [0-1)"},
		{"b", "M.UF0", "", "cannot apply 'F' to map[struct{x int}]struct{y int} (got *types.Map, want struct)"},
		{"b", "V.KO", "", "cannot apply 'K' to []*a.T (got *types.Slice, want map)"},
		{"b", "V.A4", "", "cannot apply 'A' to []*a.T (got *types.Slice, want tuple)"},
		{"b", "V.RA0", "", "cannot apply 'R' to []*a.T (got *types.Slice, want signature)"},
		{"b", "F.PA4", "", "tuple index 4 out of range [0-4)"},
		{"b", "F.XO", "", "invalid path: unknown code 'X'"},
	}
	for _, test := range paths {
		if err := testPath(pkgmap, test); err != nil {
			t.Error(err)
		}
	}

	// bad objects
	b := pkgmap["x.io/b"]
	for _, test := range []struct {
		obj     types.Object
		wantErr string
	}{
		{types.Universe.Lookup("nil"), "predeclared nil has no path"},
		{types.Universe.Lookup("len"), "predeclared builtin len has no path"},
		{types.Universe.Lookup("int"), "predeclared type int has no path"},
		{b.TypesInfo.Implicits[b.Syntax[0].Imports[0]], "no path for package a (\"a\")"}, // import "a"
		{b.Types.Scope().Lookup("unexportedFunc"), "no path for non-exported func b.unexportedFunc()"},
	} {
		path, err := objectpath.For(test.obj)
		if err == nil {
			t.Errorf("Object(%s) = %q, want error", test.obj, path)
			continue
		}
		gotErr := strings.ReplaceAll(err.Error(), "x.io/", "")
		if gotErr != test.wantErr {
			t.Errorf("Object(%s) error was %q, want %q", test.obj, gotErr, test.wantErr)
			continue
		}
	}
}

// loadPackages expands the archive and loads the package patterns relative to its root.
func loadPackages(t *testing.T, archive string, patterns ...string) map[string]*packages.Package {
	// TODO(adonovan): ExtractTxtarToTmp (sans File) would be useful.
	ar := txtar.Parse([]byte(archive))
	pkgs := testfiles.LoadPackages(t, ar, patterns...)
	m := make(map[string]*packages.Package)
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		m[pkg.Types.Path()] = pkg
	})
	return m
}

type pathTest struct {
	pkg     string // sans "x.io/" module prefix
	path    objectpath.Path
	wantobj string
	wantErr string // after each "x.io/" replaced with ""
}

func testPath(pkgmap map[string]*packages.Package, test pathTest) error {
	// We test objectpath by enumerating a set of paths
	// and ensuring that Path(pkg, Object(pkg, path)) == path.
	//
	// It might seem more natural to invert the test:
	// identify a set of objects and for each one,
	// ensure that Object(pkg, Path(pkg, obj)) == obj.
	// However, for most interesting test cases there is no
	// easy way to identify the object short of applying
	// a series of destructuring operations to pkg---which
	// is essentially what objectpath.Object does.
	// (We do a little of that when testing bad paths, below.)
	//
	// The downside is that the test depends on the path encoding.
	// The upside is that the test exercises the encoding.
	pkg := pkgmap["x.io/"+test.pkg].Types

	// check path -> object
	obj, err := objectpath.Object(pkg, test.path)
	if (test.wantErr != "") != (err != nil) {
		return fmt.Errorf("Object(%s, %q) returned error %q, want %q", pkg.Path(), test.path, err, test.wantErr)
	}
	if test.wantErr != "" {
		gotErr := strings.ReplaceAll(err.Error(), "x.io/", "")
		if gotErr != test.wantErr {
			return fmt.Errorf("Object(%s, %q) error was %q, want %q",
				pkg.Path(), test.path, gotErr, test.wantErr)
		}
		return nil
	}
	// Inv: err == nil

	if objString := types.ObjectString(obj, (*types.Package).Name); objString != test.wantobj {
		return fmt.Errorf("Object(%s, %q) = %s, want %s", pkg.Path(), test.path, objString, test.wantobj)
	}
	if obj.Pkg() != pkg {
		return fmt.Errorf("Object(%s, %q) = %v, which belongs to package %s",
			pkg.Path(), test.path, obj, obj.Pkg().Path())
	}

	// check object -> path
	path2, err := objectpath.For(obj)
	if err != nil {
		return fmt.Errorf("For(%v) failed: %v, want %q", obj, err, test.path)
	}
	// We do not require that test.path == path2. Aliases are legal.
	// But we do require that Object(path2) finds the same object.
	obj2, err := objectpath.Object(pkg, path2)
	if err != nil {
		return fmt.Errorf("Object(%s, %q) failed: %v (roundtrip from %q)", pkg.Path(), path2, err, test.path)
	}
	if obj2 != obj {
		return fmt.Errorf("Object(%s, For(obj)) != obj: got %s, obj is %s (path1=%q, path2=%q)", pkg.Path(), obj2, obj, test.path, path2)
	}
	return nil
}

// TestSourceAndExportData uses objectpath to compute a correspondence
// of objects between two versions of the same package, one loaded from
// source, the other from export data.
func TestSourceAndExportData(t *testing.T) {
	const src = `
package p

type I int

func (I) F() *struct{ X, Y int } {
	return nil
}

type Foo interface {
	Method() (string, func(int) struct{ X int })
}

var X chan struct{ Z int }
var Z map[string]struct{ A int }

var V unexported
type unexported struct{}
func (unexported) F() {} // reachable via V

// The name 'unreachable' has special meaning to the test.
type unreachable struct{}
func (unreachable) F() {} // not reachable in export data
`

	// Parse source file and type-check it as a package, "src".
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "src.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	conf := types.Config{Importer: importer.ForCompiler(token.NewFileSet(), "source", nil)}
	info := &types.Info{
		Defs: make(map[*ast.Ident]types.Object),
	}
	srcpkg, err := conf.Check("src/p", fset, []*ast.File{f}, info)
	if err != nil {
		t.Fatal(err)
	}

	// Export binary export data then reload it as a new package, "bin".
	var buf bytes.Buffer
	if err := gcexportdata.Write(&buf, fset, srcpkg); err != nil {
		t.Fatal(err)
	}

	imports := make(map[string]*types.Package)
	binpkg, err := gcexportdata.Read(&buf, fset, imports, "bin/p")
	if err != nil {
		t.Fatal(err)
	}

	// Now find the correspondences between them.
	for _, srcobj := range info.Defs {
		if srcobj == nil {
			continue // e.g. package declaration
		}
		if _, ok := srcobj.(*types.PkgName); ok {
			continue // PkgName has no objectpath
		}

		path, err := objectpath.For(srcobj)
		if err != nil {
			t.Errorf("For(%v): %v", srcobj, err)
			continue
		}

		// Do we expect to find this object in the export data?
		reachable := !strings.Contains(string(path), "unreachable")

		binobj, err := objectpath.Object(binpkg, path)
		if err != nil {
			if reachable {
				t.Errorf("Object(%s, %q): %v", binpkg.Path(), path, err)
			}
			continue
		}
		if !reachable {
			t.Errorf("Object(%s, %q) = %v (unexpectedly reachable)", binpkg.Path(), path, binobj)
		}

		// Check the object strings match.
		// (We can't check that types are identical because the
		// objects belong to different type-checker realms.)
		srcstr := objectString(srcobj)
		binstr := objectString(binobj)
		if srcstr != binstr {
			t.Errorf("ObjectStrings do not match: Object(For(%q)) = %s, want %s",
				path, srcstr, binstr)
			continue
		}
	}
}

func objectString(obj types.Object) string {
	s := types.ObjectString(obj, (*types.Package).Name)

	// The printing of interface methods changed in go1.11.
	// This work-around makes the specific test pass with earlier versions.
	s = strings.Replace(s, "func (interface).Method", "func (p.Foo).Method", -1)

	return s
}

// TestOrdering uses objectpath over two Named types with the same method
// names but in a different source order and checks that objectpath is the
// same for methods with the same name.
func TestOrdering(t *testing.T) {
	const src = `
-- go.mod --
module x.io

-- p/p.go --
package p

type T struct{ A int }

func (T) M() { }
func (T) N() { }
func (T) X() { }
func (T) Y() { }

-- q/q.go --
package q

type T struct{ A int }

func (T) N() { }
func (T) M() { }
func (T) Y() { }
func (T) X() { }
`

	pkgmap := loadPackages(t, src, "./p", "./q")
	p := pkgmap["x.io/p"].Types
	q := pkgmap["x.io/q"].Types

	// From here, the objectpaths generated for p and q should be the
	// same. If they are not, then we are generating an ordering that is
	// dependent on the declaration of the types within the file.
	for _, test := range []struct {
		path objectpath.Path
	}{
		{"T.M0"},
		{"T.M1"},
		{"T.M2"},
		{"T.M3"},
	} {
		pobj, err := objectpath.Object(p, test.path)
		if err != nil {
			t.Errorf("Object(%s) failed in a1: %v", test.path, err)
			continue
		}
		qobj, err := objectpath.Object(q, test.path)
		if err != nil {
			t.Errorf("Object(%s) failed in a2: %v", test.path, err)
			continue
		}
		if pobj.Name() != pobj.Name() {
			t.Errorf("Objects(%s) not equal, got a1 = %v, a2 = %v", test.path, pobj.Name(), qobj.Name())
		}
	}
}


================================================
FILE: go/types/typeutil/callee.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil

import (
	"go/ast"
	"go/types"
	_ "unsafe" // for linkname
)

// Callee returns the named target of a function call, if any:
// a function, method, builtin, or variable.
// It returns nil for a T(x) conversion.
//
// Functions and methods may potentially have type parameters.
//
// Note: for calls of instantiated functions and methods, Callee returns
// the corresponding generic function or method on the generic type.
func Callee(info *types.Info, call *ast.CallExpr) types.Object {
	obj := info.Uses[usedIdent(info, call.Fun)]
	if obj == nil {
		return nil
	}
	if _, ok := obj.(*types.TypeName); ok {
		return nil
	}
	return obj
}

// StaticCallee returns the target (function or method) of a static function
// call, if any. It returns nil for calls to builtins.
//
// Note: for calls of instantiated functions and methods, StaticCallee returns
// the corresponding generic function or method on the generic type.
func StaticCallee(info *types.Info, call *ast.CallExpr) *types.Func {
	obj := info.Uses[usedIdent(info, call.Fun)]
	fn, _ := obj.(*types.Func)
	if fn == nil || interfaceMethod(fn) {
		return nil
	}
	return fn
}

// usedIdent is the implementation of [internal/typesinternal.UsedIdent].
// It returns the identifier associated with e.
// See typesinternal.UsedIdent for a fuller description.
// This function should live in typesinternal, but cannot because it would
// create an import cycle.
//
//go:linkname usedIdent golang.org/x/tools/go/types/typeutil.usedIdent
func usedIdent(info *types.Info, e ast.Expr) *ast.Ident {
	if info.Types == nil || info.Uses == nil {
		panic("one of info.Types or info.Uses is nil; both must be populated")
	}
	// Look through type instantiation if necessary.
	switch d := ast.Unparen(e).(type) {
	case *ast.IndexExpr:
		if info.Types[d.Index].IsType() {
			e = d.X
		}
	case *ast.IndexListExpr:
		e = d.X
	}

	switch e := ast.Unparen(e).(type) {
	// info.Uses always has the object we want, even for selector expressions.
	// We don't need info.Selections.
	// See go/types/recording.go:recordSelection.
	case *ast.Ident:
		return e
	case *ast.SelectorExpr:
		return e.Sel
	}
	return nil
}

// interfaceMethod reports whether its argument is a method of an interface.
// This function should live in typesinternal, but cannot because it would create an import cycle.
//
//go:linkname interfaceMethod golang.org/x/tools/go/types/typeutil.interfaceMethod
func interfaceMethod(f *types.Func) bool {
	recv := f.Signature().Recv()
	return recv != nil && types.IsInterface(recv.Type())
}


================================================
FILE: go/types/typeutil/callee_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"strings"
	"testing"

	"golang.org/x/tools/go/types/typeutil"
)

func TestStaticCallee(t *testing.T) {
	testStaticCallee(t, []string{
		`package q;
		func Abs(x int) int {
			if x < 0 {
				return -x
			}
			return x
		}`,
		`package p
		import "q"

		type T int

		func g(int)

		var f = g

		var x int

		type s struct{ f func(int) }
		func (s) g(int)

		type I interface{ f(int) }

		var a struct{b struct{c s}}

		var n map[int]func()
		var m []func()

		func calls() {
			g(x)           // a declared func
			s{}.g(x)       // a concrete method
			a.b.c.g(x)     // same
			_ = q.Abs(x)   // declared func, qualified identifier
		}

		func noncalls() {
			_ = T(x)    // a type
			f(x)        // a var
			panic(x)    // a built-in
			s{}.f(x)    // a field
			I(nil).f(x) // interface method
			m[0]()      // a map
			n[0]()      // a slice
		}
		`})
}

func TestTypeParamStaticCallee(t *testing.T) {
	testStaticCallee(t, []string{
		`package q
		func R[T any]() {}
		`,
		`package p
		import "q"
		type I interface{
			i()
		}

		type G[T any] func() T
		func F[T any]() T { var x T; return x }

		type M[T I] struct{ t T }
		func (m M[T]) noncalls() {
			m.t.i()   // method on a type parameter
		}

		func (m M[T]) calls() {
			m.calls() // method on a generic type
		}

		type Chain[T I] struct{ r struct { s M[T] } }

		type S int
		func (S) i() {}

		func Multi[TP0, TP1 any](){}

		func calls() {
			_ = F[int]()            // instantiated function
			_ = (F[int])()          // go through parens
			M[S]{}.calls()          // instantiated method
			Chain[S]{}.r.s.calls()  // same as above
			Multi[int,string]()     // multiple type parameters
			q.R[int]()              // different package
		}

		func noncalls() {
			_ = G[int](nil)()  // instantiated function
		}
		`})
}

// testStaticCallee parses and type checks each file content in contents
// as a single file package in order. Within functions that have the suffix
// "calls" it checks that the CallExprs within have a static callee.
// If the function's name == "calls" all calls must have static callees,
// and if the name != "calls", the calls must not have static callees.
// Failures are reported on t.
func testStaticCallee(t *testing.T, contents []string) {
	fset := token.NewFileSet()
	packages := make(map[string]*types.Package)
	cfg := &types.Config{Importer: closure(packages)}
	info := &types.Info{
		Instances:    make(map[*ast.Ident]types.Instance),
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Uses:         make(map[*ast.Ident]types.Object),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		FileVersions: make(map[*ast.File]string),
	}

	var files []*ast.File
	for i, content := range contents {
		// parse
		f, err := parser.ParseFile(fset, fmt.Sprintf("%d.go", i), content, 0)
		if err != nil {
			t.Fatal(err)
		}
		files = append(files, f)

		// type-check
		pkg, err := cfg.Check(f.Name.Name, fset, []*ast.File{f}, info)
		if err != nil {
			t.Fatal(err)
		}
		packages[pkg.Path()] = pkg
	}

	// check
	for _, f := range files {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok && strings.HasSuffix(decl.Name.Name, "calls") {
				wantCallee := decl.Name.Name == "calls" // false within func noncalls()
				ast.Inspect(decl.Body, func(n ast.Node) bool {
					if call, ok := n.(*ast.CallExpr); ok {
						fn := typeutil.StaticCallee(info, call)
						if fn == nil && wantCallee {
							t.Errorf("%s: StaticCallee returned nil",
								fset.Position(call.Lparen))
						} else if fn != nil && !wantCallee {
							t.Errorf("%s: StaticCallee returned %s, want nil",
								fset.Position(call.Lparen), fn)
						}
					}
					return true
				})
			}
		}
	}
}


================================================
FILE: go/types/typeutil/example_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"sort"

	"golang.org/x/tools/go/types/typeutil"
)

func ExampleMap() {
	const source = `package P

var X []string
var Y []string

const p, q = 1.0, 2.0

func f(offset int32) (value byte, ok bool)
func g(rune) (uint8, bool)
`

	// Parse and type-check the package.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "P.go", source, 0)
	if err != nil {
		panic(err)
	}
	pkg, err := new(types.Config).Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		panic(err)
	}

	scope := pkg.Scope()

	// Group names of package-level objects by their type.
	var namesByType typeutil.Map // value is []string
	for _, name := range scope.Names() {
		T := scope.Lookup(name).Type()

		names, _ := namesByType.At(T).([]string)
		names = append(names, name)
		namesByType.Set(T, names)
	}

	// Format, sort, and print the map entries.
	var lines []string
	namesByType.Iterate(func(T types.Type, names any) {
		lines = append(lines, fmt.Sprintf("%s   %s", names, T))
	})
	sort.Strings(lines)
	for _, line := range lines {
		fmt.Println(line)
	}

	// Output:
	// [X Y]   []string
	// [f g]   func(offset int32) (value byte, ok bool)
	// [p q]   untyped float
}


================================================
FILE: go/types/typeutil/imports.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil

import "go/types"

// Dependencies returns all dependencies of the specified packages.
//
// Dependent packages appear in topological order: if package P imports
// package Q, Q appears earlier than P in the result.
// The algorithm follows import statements in the order they
// appear in the source code, so the result is a total order.
func Dependencies(pkgs ...*types.Package) []*types.Package {
	var result []*types.Package
	seen := make(map[*types.Package]bool)
	var visit func(pkgs []*types.Package)
	visit = func(pkgs []*types.Package) {
		for _, p := range pkgs {
			if !seen[p] {
				seen[p] = true
				visit(p.Imports())
				result = append(result, p)
			}
		}
	}
	visit(pkgs)
	return result
}


================================================
FILE: go/types/typeutil/imports_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/go/types/typeutil"
)

type closure map[string]*types.Package

func (c closure) Import(path string) (*types.Package, error) { return c[path], nil }

func TestDependencies(t *testing.T) {
	packages := make(map[string]*types.Package)
	conf := types.Config{
		Importer: closure(packages),
	}
	fset := token.NewFileSet()

	// All edges go to the right.
	//  /--D--B--A
	// F    \_C_/
	//  \__E_/
	for i, content := range []string{
		`package a`,
		`package c; import (_ "a")`,
		`package b; import (_ "a")`,
		`package e; import (_ "c")`,
		`package d; import (_ "b"; _ "c")`,
		`package f; import (_ "d"; _ "e")`,
	} {
		f, err := parser.ParseFile(fset, fmt.Sprintf("%d.go", i), content, 0)
		if err != nil {
			t.Fatal(err)
		}
		pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
		if err != nil {
			t.Fatal(err)
		}
		packages[pkg.Path()] = pkg
	}

	for _, test := range []struct {
		roots, want string
	}{
		{"a", "a"},
		{"b", "ab"},
		{"c", "ac"},
		{"d", "abcd"},
		{"e", "ace"},
		{"f", "abcdef"},

		{"be", "abce"},
		{"eb", "aceb"},
		{"de", "abcde"},
		{"ed", "acebd"},
		{"ef", "acebdf"},
	} {
		var pkgs []*types.Package
		for _, r := range test.roots {
			pkgs = append(pkgs, packages[string(r)])
		}
		var got string
		for _, p := range typeutil.Dependencies(pkgs...) {
			got += p.Path()
		}
		if got != test.want {
			t.Errorf("Dependencies(%q) = %q, want %q", test.roots, got, test.want)
		}
	}
}


================================================
FILE: go/types/typeutil/map.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typeutil defines various utilities for types, such as [Map],
// a hash table that maps [types.Type] to any value.
package typeutil

import (
	"bytes"
	"fmt"
	"go/types"
	"hash/maphash"

	"golang.org/x/tools/internal/typeparams"
)

// Map is a hash-table-based mapping from types (types.Type) to
// arbitrary values.  The concrete types that implement
// the Type interface are pointers.  Since they are not canonicalized,
// == cannot be used to check for equivalence, and thus we cannot
// simply use a Go map.
//
// Just as with map[K]V, a nil *Map is a valid empty map.
//
// Read-only map operations ([Map.At], [Map.Len], and so on) may
// safely be called concurrently.
//
// TODO(adonovan): deprecate in favor of https://go.dev/issues/69420
// and 69559, if the latter proposals for a generic hash-map type and
// a types.Hash function are accepted.
type Map struct {
	table  map[uint32][]entry // maps hash to bucket; entry.key==nil means unused
	length int                // number of map entries
}

// entry is an entry (key/value association) in a hash bucket.
type entry struct {
	key   types.Type
	value any
}

// SetHasher has no effect.
//
// It is a relic of an optimization that is no longer profitable. Do
// not use [Hasher], [MakeHasher], or [SetHasher] in new code.
func (m *Map) SetHasher(Hasher) {}

// Delete removes the entry with the given key, if any.
// It returns true if the entry was found.
func (m *Map) Delete(key types.Type) bool {
	if m != nil && m.table != nil {
		hash := hash(key)
		bucket := m.table[hash]
		for i, e := range bucket {
			if e.key != nil && types.Identical(key, e.key) {
				// We can't compact the bucket as it
				// would disturb iterators.
				bucket[i] = entry{}
				m.length--
				return true
			}
		}
	}
	return false
}

// At returns the map entry for the given key.
// The result is nil if the entry is not present.
func (m *Map) At(key types.Type) any {
	if m != nil && m.table != nil {
		for _, e := range m.table[hash(key)] {
			if e.key != nil && types.Identical(key, e.key) {
				return e.value
			}
		}
	}
	return nil
}

// Set sets the map entry for key to val,
// and returns the previous entry, if any.
func (m *Map) Set(key types.Type, value any) (prev any) {
	if m.table != nil {
		hash := hash(key)
		bucket := m.table[hash]
		var hole *entry
		for i, e := range bucket {
			if e.key == nil {
				hole = &bucket[i]
			} else if types.Identical(key, e.key) {
				prev = e.value
				bucket[i].value = value
				return
			}
		}

		if hole != nil {
			*hole = entry{key, value} // overwrite deleted entry
		} else {
			m.table[hash] = append(bucket, entry{key, value})
		}
	} else {
		hash := hash(key)
		m.table = map[uint32][]entry{hash: {entry{key, value}}}
	}

	m.length++
	return
}

// Len returns the number of map entries.
func (m *Map) Len() int {
	if m != nil {
		return m.length
	}
	return 0
}

// Iterate calls function f on each entry in the map in unspecified order.
//
// If f should mutate the map, Iterate provides the same guarantees as
// Go maps: if f deletes a map entry that Iterate has not yet reached,
// f will not be invoked for it, but if f inserts a map entry that
// Iterate has not yet reached, whether or not f will be invoked for
// it is unspecified.
func (m *Map) Iterate(f func(key types.Type, value any)) {
	if m != nil {
		for _, bucket := range m.table {
			for _, e := range bucket {
				if e.key != nil {
					f(e.key, e.value)
				}
			}
		}
	}
}

// Keys returns a new slice containing the set of map keys.
// The order is unspecified.
func (m *Map) Keys() []types.Type {
	keys := make([]types.Type, 0, m.Len())
	m.Iterate(func(key types.Type, _ any) {
		keys = append(keys, key)
	})
	return keys
}

func (m *Map) toString(values bool) string {
	if m == nil {
		return "{}"
	}
	var buf bytes.Buffer
	fmt.Fprint(&buf, "{")
	sep := ""
	m.Iterate(func(key types.Type, value any) {
		fmt.Fprint(&buf, sep)
		sep = ", "
		fmt.Fprint(&buf, key)
		if values {
			fmt.Fprintf(&buf, ": %q", value)
		}
	})
	fmt.Fprint(&buf, "}")
	return buf.String()
}

// String returns a string representation of the map's entries.
// Values are printed using fmt.Sprintf("%v", v).
// Order is unspecified.
func (m *Map) String() string {
	return m.toString(true)
}

// KeysString returns a string representation of the map's key set.
// Order is unspecified.
func (m *Map) KeysString() string {
	return m.toString(false)
}

// -- Hasher --

// hash returns the hash of type t.
// TODO(adonovan): replace by types.Hash when Go proposal #69420 is accepted.
func hash(t types.Type) uint32 {
	return theHasher.Hash(t)
}

// A Hasher provides a [Hasher.Hash] method to map a type to its hash value.
// Hashers are stateless, and all are equivalent.
type Hasher struct{}

var theHasher Hasher

// MakeHasher returns Hasher{}.
// Hashers are stateless; all are equivalent.
func MakeHasher() Hasher { return theHasher }

// Hash computes a hash value for the given type t such that
// Identical(t, t') => Hash(t) == Hash(t').
func (h Hasher) Hash(t types.Type) uint32 {
	return hasher{inGenericSig: false}.hash(t)
}

// hasher holds the state of a single Hash traversal: whether we are
// inside the signature of a generic function; this is used to
// optimize [hasher.hashTypeParam].
type hasher struct{ inGenericSig bool }

// hashString computes the Fowler–Noll–Vo hash of s.
func hashString(s string) uint32 {
	var h uint32
	for i := 0; i < len(s); i++ {
		h ^= uint32(s[i])
		h *= 16777619
	}
	return h
}

// hash computes the hash of t.
func (h hasher) hash(t types.Type) uint32 {
	// See Identical for rationale.
	switch t := t.(type) {
	case *types.Basic:
		return uint32(t.Kind())

	case *types.Alias:
		return h.hash(types.Unalias(t))

	case *types.Array:
		return 9043 + 2*uint32(t.Len()) + 3*h.hash(t.Elem())

	case *types.Slice:
		return 9049 + 2*h.hash(t.Elem())

	case *types.Struct:
		var hash uint32 = 9059
		for i, n := 0, t.NumFields(); i < n; i++ {
			f := t.Field(i)
			if f.Anonymous() {
				hash += 8861
			}
			hash += hashString(t.Tag(i))
			hash += hashString(f.Name()) // (ignore f.Pkg)
			hash += h.hash(f.Type())
		}
		return hash

	case *types.Pointer:
		return 9067 + 2*h.hash(t.Elem())

	case *types.Signature:
		var hash uint32 = 9091
		if t.Variadic() {
			hash *= 8863
		}

		tparams := t.TypeParams()
		if n := tparams.Len(); n > 0 {
			h.inGenericSig = true // affects constraints, params, and results

			for i := range n {
				tparam := tparams.At(i)
				hash += 7 * h.hash(tparam.Constraint())
			}
		}

		return hash + 3*h.hashTuple(t.Params()) + 5*h.hashTuple(t.Results())

	case *types.Union:
		return h.hashUnion(t)

	case *types.Interface:
		// Interfaces are identical if they have the same set of methods, with
		// identical names and types, and they have the same set of type
		// restrictions. See go/types.identical for more details.
		var hash uint32 = 9103

		// Hash methods.
		for i, n := 0, t.NumMethods(); i < n; i++ {
			// Method order is not significant.
			// Ignore m.Pkg().
			m := t.Method(i)
			// Use shallow hash on method signature to
			// avoid anonymous interface cycles.
			hash += 3*hashString(m.Name()) + 5*h.shallowHash(m.Type())
		}

		// Hash type restrictions.
		terms, err := typeparams.InterfaceTermSet(t)
		// if err != nil t has invalid type restrictions.
		if err == nil {
			hash += h.hashTermSet(terms)
		}

		return hash

	case *types.Map:
		return 9109 + 2*h.hash(t.Key()) + 3*h.hash(t.Elem())

	case *types.Chan:
		return 9127 + 2*uint32(t.Dir()) + 3*h.hash(t.Elem())

	case *types.Named:
		hash := h.hashTypeName(t.Obj())
		targs := t.TypeArgs()
		for targ := range targs.Types() {
			hash += 2 * h.hash(targ)
		}
		return hash

	case *types.TypeParam:
		return h.hashTypeParam(t)

	case *types.Tuple:
		return h.hashTuple(t)
	}

	panic(fmt.Sprintf("%T: %v", t, t))
}

func (h hasher) hashTuple(tuple *types.Tuple) uint32 {
	// See go/types.identicalTypes for rationale.
	n := tuple.Len()
	hash := 9137 + 2*uint32(n)
	for i := range n {
		hash += 3 * h.hash(tuple.At(i).Type())
	}
	return hash
}

func (h hasher) hashUnion(t *types.Union) uint32 {
	// Hash type restrictions.
	terms, err := typeparams.UnionTermSet(t)
	// if err != nil t has invalid type restrictions. Fall back on a non-zero
	// hash.
	if err != nil {
		return 9151
	}
	return h.hashTermSet(terms)
}

func (h hasher) hashTermSet(terms []*types.Term) uint32 {
	hash := 9157 + 2*uint32(len(terms))
	for _, term := range terms {
		// term order is not significant.
		termHash := h.hash(term.Type())
		if term.Tilde() {
			termHash *= 9161
		}
		hash += 3 * termHash
	}
	return hash
}

// hashTypeParam returns the hash of a type parameter.
func (h hasher) hashTypeParam(t *types.TypeParam) uint32 {
	// Within the signature of a generic function, TypeParams are
	// identical if they have the same index and constraint, so we
	// hash them based on index.
	//
	// When we are outside a generic function, free TypeParams are
	// identical iff they are the same object, so we can use a
	// more discriminating hash consistent with object identity.
	// This optimization saves [Map] about 4% when hashing all the
	// types.Info.Types in the forward closure of net/http.
	if !h.inGenericSig {
		// Optimization: outside a generic function signature,
		// use a more discrimating hash consistent with object identity.
		return h.hashTypeName(t.Obj())
	}
	return 9173 + 3*uint32(t.Index())
}

var theSeed = maphash.MakeSeed()

// hashTypeName hashes the pointer of tname.
func (hasher) hashTypeName(tname *types.TypeName) uint32 {
	// Since types.Identical uses == to compare TypeNames,
	// the Hash function uses maphash.Comparable.
	hash := maphash.Comparable(theSeed, tname)
	return uint32(hash ^ (hash >> 32))
}

// shallowHash computes a hash of t without looking at any of its
// element Types, to avoid potential anonymous cycles in the types of
// interface methods.
//
// When an unnamed non-empty interface type appears anywhere among the
// arguments or results of an interface method, there is a potential
// for endless recursion. Consider:
//
//	type X interface { m() []*interface { X } }
//
// The problem is that the Methods of the interface in m's result type
// include m itself; there is no mention of the named type X that
// might help us break the cycle.
// (See comment in go/types.identical, case *Interface, for more.)
func (h hasher) shallowHash(t types.Type) uint32 {
	// t is the type of an interface method (Signature),
	// its params or results (Tuples), or their immediate
	// elements (mostly Slice, Pointer, Basic, Named),
	// so there's no need to optimize anything else.
	switch t := t.(type) {
	case *types.Alias:
		return h.shallowHash(types.Unalias(t))

	case *types.Signature:
		var hash uint32 = 604171
		if t.Variadic() {
			hash *= 971767
		}
		// The Signature/Tuple recursion is always finite
		// and invariably shallow.
		return hash + 1062599*h.shallowHash(t.Params()) + 1282529*h.shallowHash(t.Results())

	case *types.Tuple:
		n := t.Len()
		hash := 9137 + 2*uint32(n)
		for i := range n {
			hash += 53471161 * h.shallowHash(t.At(i).Type())
		}
		return hash

	case *types.Basic:
		return 45212177 * uint32(t.Kind())

	case *types.Array:
		return 1524181 + 2*uint32(t.Len())

	case *types.Slice:
		return 2690201

	case *types.Struct:
		return 3326489

	case *types.Pointer:
		return 4393139

	case *types.Union:
		return 562448657

	case *types.Interface:
		return 2124679 // no recursion here

	case *types.Map:
		return 9109

	case *types.Chan:
		return 9127

	case *types.Named:
		return h.hashTypeName(t.Obj())

	case *types.TypeParam:
		return h.hashTypeParam(t)
	}
	panic(fmt.Sprintf("shallowHash: %T: %v", t, t))
}


================================================
FILE: go/types/typeutil/map_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil_test

// TODO(adonovan):
// - test use of explicit hasher across two maps.
// - test hashcodes are consistent with equals for a range of types
//   (e.g. all types generated by type-checking some body of real code).

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/testenv"
)

var (
	tStr      = types.Typ[types.String]             // string
	tPStr1    = types.NewPointer(tStr)              // *string
	tPStr2    = types.NewPointer(tStr)              // *string, again
	tInt      = types.Typ[types.Int]                // int
	tChanInt1 = types.NewChan(types.RecvOnly, tInt) // <-chan int
	tChanInt2 = types.NewChan(types.RecvOnly, tInt) // <-chan int, again
)

func checkEqualButNotIdentical(t *testing.T, x, y types.Type, comment string) {
	if !types.Identical(x, y) {
		t.Errorf("%s: not equal: %s, %s", comment, x, y)
	}
	if x == y {
		t.Errorf("%s: identical: %v, %v", comment, x, y)
	}
}

func TestAxioms(t *testing.T) {
	checkEqualButNotIdentical(t, tPStr1, tPStr2, "tPstr{1,2}")
	checkEqualButNotIdentical(t, tChanInt1, tChanInt2, "tChanInt{1,2}")
}

func TestMap(t *testing.T) {
	var tmap *typeutil.Map

	// All methods but Set are safe on (*T)(nil).
	tmap.Len()
	tmap.At(tPStr1)
	tmap.Delete(tPStr1)
	tmap.KeysString()
	_ = tmap.String()

	tmap = new(typeutil.Map)

	// Length of empty map.
	if l := tmap.Len(); l != 0 {
		t.Errorf("Len() on empty Map: got %d, want 0", l)
	}
	// At of missing key.
	if v := tmap.At(tPStr1); v != nil {
		t.Errorf("At() on empty Map: got %v, want nil", v)
	}
	// Deletion of missing key.
	if tmap.Delete(tPStr1) {
		t.Errorf("Delete() on empty Map: got true, want false")
	}
	// Set of new key.
	if prev := tmap.Set(tPStr1, "*string"); prev != nil {
		t.Errorf("Set() on empty Map returned non-nil previous value %s", prev)
	}

	// Now: {*string: "*string"}

	// Length of non-empty map.
	if l := tmap.Len(); l != 1 {
		t.Errorf("Len(): got %d, want 1", l)
	}
	// At via insertion key.
	if v := tmap.At(tPStr1); v != "*string" {
		t.Errorf("At(): got %q, want \"*string\"", v)
	}
	// At via equal key.
	if v := tmap.At(tPStr2); v != "*string" {
		t.Errorf("At(): got %q, want \"*string\"", v)
	}
	// Iteration over sole entry.
	tmap.Iterate(func(key types.Type, value any) {
		if key != tPStr1 {
			t.Errorf("Iterate: key: got %s, want %s", key, tPStr1)
		}
		if want := "*string"; value != want {
			t.Errorf("Iterate: value: got %s, want %s", value, want)
		}
	})

	// Setion with key equal to present one.
	if prev := tmap.Set(tPStr2, "*string again"); prev != "*string" {
		t.Errorf("Set() previous value: got %s, want \"*string\"", prev)
	}

	// Setion of another association.
	if prev := tmap.Set(tChanInt1, "<-chan int"); prev != nil {
		t.Errorf("Set() previous value: got %s, want nil", prev)
	}

	// Now: {*string: "*string again", <-chan int: "<-chan int"}

	want1 := "{*string: \"*string again\", <-chan int: \"<-chan int\"}"
	want2 := "{<-chan int: \"<-chan int\", *string: \"*string again\"}"
	if s := tmap.String(); s != want1 && s != want2 {
		t.Errorf("String(): got %s, want %s", s, want1)
	}

	want1 = "{*string, <-chan int}"
	want2 = "{<-chan int, *string}"
	if s := tmap.KeysString(); s != want1 && s != want2 {
		t.Errorf("KeysString(): got %s, want %s", s, want1)
	}

	// Keys().
	I := types.Identical
	switch k := tmap.Keys(); {
	case I(k[0], tChanInt1) && I(k[1], tPStr1): // ok
	case I(k[1], tChanInt1) && I(k[0], tPStr1): // ok
	default:
		t.Errorf("Keys(): got %v, want %s", k, want2)
	}

	if l := tmap.Len(); l != 2 {
		t.Errorf("Len(): got %d, want 1", l)
	}
	// At via original key.
	if v := tmap.At(tPStr1); v != "*string again" {
		t.Errorf("At(): got %q, want \"*string again\"", v)
	}
	hamming := 1
	tmap.Iterate(func(key types.Type, value any) {
		switch {
		case I(key, tChanInt1):
			hamming *= 2 // ok
		case I(key, tPStr1):
			hamming *= 3 // ok
		}
	})
	if hamming != 6 {
		t.Errorf("Iterate: hamming: got %d, want %d", hamming, 6)
	}

	if v := tmap.At(tChanInt2); v != "<-chan int" {
		t.Errorf("At(): got %q, want \"<-chan int\"", v)
	}
	// Deletion with key equal to present one.
	if !tmap.Delete(tChanInt2) {
		t.Errorf("Delete() of existing key: got false, want true")
	}

	// Now: {*string: "*string again"}

	if l := tmap.Len(); l != 1 {
		t.Errorf("Len(): got %d, want 1", l)
	}
	// Deletion again.
	if !tmap.Delete(tPStr2) {
		t.Errorf("Delete() of existing key: got false, want true")
	}

	// Now: {}

	if l := tmap.Len(); l != 0 {
		t.Errorf("Len(): got %d, want %d", l, 0)
	}
	if s := tmap.String(); s != "{}" {
		t.Errorf("Len(): got %q, want %q", s, "")
	}
}

func TestMapGenerics(t *testing.T) {
	const src = `
package p

// Basic defined types.
type T1 int
type T2 int

// Identical methods.
func (T1) M(int) {}
func (T2) M(int) {}

// A constraint interface.
type C interface {
	~int | string
}

type I interface {
}

// A generic type.
type G[P C] int

// Generic functions with identical signature.
func Fa1[P C](p P) {}
func Fa2[Q C](q Q) {}

// Fb1 and Fb2 are identical and should be mapped to the same entry, even if we
// map their arguments first.
func Fb1[P any](x *P) {
	var y *P // Map this first.
	_ = y
}
func Fb2[Q any](x *Q) {
}

// G1 and G2 are mutually recursive, and have identical methods.
type G1[P any] struct{
	Field *G2[P]
}
func (G1[P]) M(G1[P], G2[P]) {}
type G2[Q any] struct{
	Field *G1[Q]
}
func (G2[P]) M(G1[P], G2[P]) {}

// Method type expressions on different generic types are different.
var ME1 = G1[int].M
var ME2 = G2[int].M

// ME1Type should have identical type as ME1.
var ME1Type func(G1[int], G1[int], G2[int])

// Examples from issue #51314
type Constraint[T any] any
func Foo[T Constraint[T]]() {}
func Fn[T1 ~*T2, T2 ~*T1](t1 T1, t2 T2) {}

// Bar and Baz are identical to Foo.
func Bar[P Constraint[P]]() {}
func Baz[Q any]() {} // The underlying type of Constraint[P] is any.
// But Quux is not.
func Quux[Q interface{ quux() }]() {}


type Issue56048_I interface{ m() interface { Issue56048_I } }
var Issue56048 = Issue56048_I.m

type Issue56048_Ib interface{ m() chan []*interface { Issue56048_Ib } }
var Issue56048b = Issue56048_Ib.m

// Non-generic alias
type NonAlias int
type Alias1 = NonAlias
type Alias2 = NonAlias

// Generic alias (requires go1.23)
// type SetOfInt = map[int]bool
// type Set[T comparable] = map[K]bool
// type SetOfInt2 = Set[int]
`

	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("", fset, []*ast.File{file}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// Collect types.
	scope := pkg.Scope()
	var (
		T1      = scope.Lookup("T1").Type().(*types.Named)
		T2      = scope.Lookup("T2").Type().(*types.Named)
		T1M     = T1.Method(0).Type()
		T2M     = T2.Method(0).Type()
		G       = scope.Lookup("G").Type()
		GInt1   = instantiate(t, G, types.Typ[types.Int])
		GInt2   = instantiate(t, G, types.Typ[types.Int])
		GStr    = instantiate(t, G, types.Typ[types.String])
		C       = scope.Lookup("C").Type()
		CI      = C.Underlying().(*types.Interface)
		I       = scope.Lookup("I").Type()
		II      = I.Underlying().(*types.Interface)
		U       = CI.EmbeddedType(0).(*types.Union)
		Fa1     = scope.Lookup("Fa1").Type().(*types.Signature)
		Fa2     = scope.Lookup("Fa2").Type().(*types.Signature)
		Fa1P    = Fa1.TypeParams().At(0)
		Fa2Q    = Fa2.TypeParams().At(0)
		Fb1     = scope.Lookup("Fb1").Type().(*types.Signature)
		Fb1x    = Fb1.Params().At(0).Type()
		Fb1y    = scope.Lookup("Fb1").(*types.Func).Scope().Lookup("y").Type()
		Fb2     = scope.Lookup("Fb2").Type().(*types.Signature)
		Fb2x    = Fb2.Params().At(0).Type()
		G1      = scope.Lookup("G1").Type().(*types.Named)
		G1M     = G1.Method(0).Type()
		G1IntM1 = instantiate(t, G1, types.Typ[types.Int]).(*types.Named).Method(0).Type()
		G1IntM2 = instantiate(t, G1, types.Typ[types.Int]).(*types.Named).Method(0).Type()
		G1StrM  = instantiate(t, G1, types.Typ[types.String]).(*types.Named).Method(0).Type()
		G2      = scope.Lookup("G2").Type()
		// See below.
		// G2M     = G2.Method(0).Type()
		G2IntM  = instantiate(t, G2, types.Typ[types.Int]).(*types.Named).Method(0).Type()
		ME1     = scope.Lookup("ME1").Type()
		ME1Type = scope.Lookup("ME1Type").Type()
		ME2     = scope.Lookup("ME2").Type()

		Constraint  = scope.Lookup("Constraint").Type()
		Foo         = scope.Lookup("Foo").Type()
		Fn          = scope.Lookup("Fn").Type()
		Bar         = scope.Lookup("Foo").Type()
		Baz         = scope.Lookup("Foo").Type()
		Quux        = scope.Lookup("Quux").Type()
		Issue56048  = scope.Lookup("Issue56048").Type()
		Issue56048b = scope.Lookup("Issue56048b").Type()

		// In go1.23 these will be *types.Alias; for now they are all int.
		NonAlias = scope.Lookup("NonAlias").Type()
		Alias1   = scope.Lookup("Alias1").Type()
		Alias2   = scope.Lookup("Alias2").Type()

		// Requires go1.23.
		// SetOfInt    = scope.Lookup("SetOfInt").Type()
		// Set         = scope.Lookup("Set").Type().(*types.Alias)
		// SetOfInt2   = scope.Lookup("SetOfInt2").Type()
	)

	tmap := new(typeutil.Map)

	steps := []struct {
		typ      types.Type
		name     string
		newEntry bool
	}{
		{T1, "T1", true},
		{T2, "T2", true},
		{G, "G", true},
		{C, "C", true},
		{CI, "CI", true},
		{U, "U", true},
		{I, "I", true},
		{II, "II", true}, // should not be identical to CI

		// Methods can be identical, even with distinct receivers.
		{T1M, "T1M", true},
		{T2M, "T2M", false},

		// Identical instances should map to the same entry.
		{GInt1, "GInt1", true},
		{GInt2, "GInt2", false},
		// ..but instantiating with different arguments should yield a new entry.
		{GStr, "GStr", true},

		// F1 and F2 should have identical signatures.
		{Fa1, "F1", true},
		{Fa2, "F2", false},

		// The identity of P and Q should not have been affected by type parameter
		// masking during signature hashing.
		{Fa1P, "F1P", true},
		{Fa2Q, "F2Q", true},

		{Fb1y, "Fb1y", true},
		{Fb1x, "Fb1x", false},
		{Fb2x, "Fb2x", true},
		{Fb1, "Fb1", true},

		// Mapping elements of the function scope should not affect the identity of
		// Fb2 or Fb1.
		{Fb2, "Fb1", false},

		{G1, "G1", true},
		{G1M, "G1M", true},
		{G2, "G2", true},

		// See golang/go#49912: receiver type parameter names should be ignored
		// when comparing method identity.
		// {G2M, "G2M", false},
		{G1IntM1, "G1IntM1", true},
		{G1IntM2, "G1IntM2", false},
		{G1StrM, "G1StrM", true},
		{G2IntM, "G2IntM", false}, // identical to G1IntM1

		{ME1, "ME1", true},
		{ME1Type, "ME1Type", false},
		{ME2, "ME2", true},

		// See golang/go#51314: avoid infinite recursion on cyclic type constraints.
		{Constraint, "Constraint", true},
		{Foo, "Foo", true},
		{Fn, "Fn", true},
		{Bar, "Bar", false},
		{Baz, "Baz", false},
		{Quux, "Quux", true},

		{Issue56048, "Issue56048", true},   // (not actually about generics)
		{Issue56048b, "Issue56048b", true}, // (not actually about generics)

		// All three types are identical.
		{NonAlias, "NonAlias", true},
		{Alias1, "Alias1", false},
		{Alias2, "Alias2", false},

		// Generic aliases: requires go1.23.
		// {SetOfInt, "SetOfInt", true},
		// {Set, "Set", false},
		// {SetOfInt2, "SetOfInt2", false},
	}

	for _, step := range steps {
		existing := tmap.At(step.typ)
		if (existing == nil) != step.newEntry {
			t.Errorf("At(%s) = %v, want new entry: %t", step.name, existing, step.newEntry)
		}
		tmap.Set(step.typ, step.name)
	}
}

func instantiate(t *testing.T, origin types.Type, targs ...types.Type) types.Type {
	inst, err := types.Instantiate(nil, origin, targs, true)
	if err != nil {
		t.Fatal(err)
	}
	return inst
}

// BenchmarkMap stores the type of every expression in the net/http
// package in a map.
func BenchmarkMap(b *testing.B) {
	testenv.NeedsGoPackages(b)

	// Load all dependencies of net/http.
	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
	pkgs, err := packages.Load(cfg, "net/http")
	if err != nil {
		b.Fatal(err)
	}

	// Gather all unique types.Type pointers (>67K) annotating the syntax.
	allTypes := make(map[types.Type]bool)
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		for _, tv := range pkg.TypesInfo.Types {
			allTypes[tv.Type] = true
		}
	})

	for b.Loop() {
		// De-duplicate the logically identical types.
		var tmap typeutil.Map
		for t := range allTypes {
			tmap.Set(t, nil)
		}

		// For sanity, ensure we find a minimum number
		// of distinct type equivalence classes.
		if want := 12000; tmap.Len() < want {
			b.Errorf("too few types (from %d types.Type values, got %d logically distinct types, want >=%d)",
				len(allTypes),
				tmap.Len(),
				want)
		}
	}
}


================================================
FILE: go/types/typeutil/methodsetcache.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements a cache of method sets.

package typeutil

import (
	"go/types"
	"sync"
)

// A MethodSetCache records the method set of each type T for which
// MethodSet(T) is called so that repeat queries are fast.
// The zero value is a ready-to-use cache instance.
type MethodSetCache struct {
	mu     sync.Mutex
	named  map[*types.Named]struct{ value, pointer *types.MethodSet } // method sets for named N and *N
	others map[types.Type]*types.MethodSet                            // all other types
}

// MethodSet returns the method set of type T.  It is thread-safe.
//
// If cache is nil, this function is equivalent to types.NewMethodSet(T).
// Utility functions can thus expose an optional *MethodSetCache
// parameter to clients that care about performance.
func (cache *MethodSetCache) MethodSet(T types.Type) *types.MethodSet {
	if cache == nil {
		return types.NewMethodSet(T)
	}
	cache.mu.Lock()
	defer cache.mu.Unlock()

	switch T := types.Unalias(T).(type) {
	case *types.Named:
		return cache.lookupNamed(T).value

	case *types.Pointer:
		if N, ok := types.Unalias(T.Elem()).(*types.Named); ok {
			return cache.lookupNamed(N).pointer
		}
	}

	// all other types
	// (The map uses pointer equivalence, not type identity.)
	mset := cache.others[T]
	if mset == nil {
		mset = types.NewMethodSet(T)
		if cache.others == nil {
			cache.others = make(map[types.Type]*types.MethodSet)
		}
		cache.others[T] = mset
	}
	return mset
}

func (cache *MethodSetCache) lookupNamed(named *types.Named) struct{ value, pointer *types.MethodSet } {
	if cache.named == nil {
		cache.named = make(map[*types.Named]struct{ value, pointer *types.MethodSet })
	}
	// Avoid recomputing mset(*T) for each distinct Pointer
	// instance whose underlying type is a named type.
	msets, ok := cache.named[named]
	if !ok {
		msets.value = types.NewMethodSet(named)
		msets.pointer = types.NewMethodSet(types.NewPointer(named))
		cache.named[named] = msets
	}
	return msets
}


================================================
FILE: go/types/typeutil/ui.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil

// This file defines utilities for user interfaces that display types.

import (
	"go/types"
)

// IntuitiveMethodSet returns the intuitive method set of a type T,
// which is the set of methods you can call on an addressable value of
// that type.
//
// The result always contains MethodSet(T), and is exactly MethodSet(T)
// for interface types and for pointer-to-concrete types.
// For all other concrete types T, the result additionally
// contains each method belonging to *T if there is no identically
// named method on T itself.
//
// This corresponds to user intuition about method sets;
// this function is intended only for user interfaces.
//
// The order of the result is as for types.MethodSet(T).
func IntuitiveMethodSet(T types.Type, msets *MethodSetCache) []*types.Selection {
	isPointerToConcrete := func(T types.Type) bool {
		ptr, ok := types.Unalias(T).(*types.Pointer)
		return ok && !types.IsInterface(ptr.Elem())
	}

	var result []*types.Selection
	mset := msets.MethodSet(T)
	if types.IsInterface(T) || isPointerToConcrete(T) {
		for i, n := 0, mset.Len(); i < n; i++ {
			result = append(result, mset.At(i))
		}
	} else {
		// T is some other concrete type.
		// Report methods of T and *T, preferring those of T.
		pmset := msets.MethodSet(types.NewPointer(T))
		for i, n := 0, pmset.Len(); i < n; i++ {
			meth := pmset.At(i)
			if m := mset.Lookup(meth.Obj().Pkg(), meth.Obj().Name()); m != nil {
				meth = m
			}
			result = append(result, meth)
		}

	}
	return result
}


================================================
FILE: go/types/typeutil/ui_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeutil_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"strings"
	"testing"

	"golang.org/x/tools/go/types/typeutil"
)

func TestIntuitiveMethodSet(t *testing.T) {
	const source = `
package P
type A int
func (A) f()
func (*A) g()
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}
	qual := types.RelativeTo(pkg)

	for _, test := range []struct {
		expr string // type expression
		want string // intuitive method set
	}{
		{"A", "(A).f (*A).g"},
		{"*A", "(*A).f (*A).g"},
		{"error", "(error).Error"},
		{"*error", ""},
		{"struct{A}", "(struct{A}).f (*struct{A}).g"},
		{"*struct{A}", "(*struct{A}).f (*struct{A}).g"},
	} {
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Errorf("Eval(%s) failed: %v", test.expr, err)
		}
		var names []string
		for _, m := range typeutil.IntuitiveMethodSet(tv.Type, nil) {
			name := fmt.Sprintf("(%s).%s", types.TypeString(m.Recv(), qual), m.Obj().Name())
			names = append(names, name)
		}
		got := strings.Join(names, " ")
		if got != test.want {
			t.Errorf("IntuitiveMethodSet(%s) = %q, want %q", test.expr, got, test.want)
		}
	}
}


================================================
FILE: go.mod
================================================
module golang.org/x/tools

go 1.25.0

require (
	github.com/google/go-cmp v0.6.0
	github.com/yuin/goldmark v1.4.13
	golang.org/x/mod v0.34.0
	golang.org/x/net v0.52.0
	golang.org/x/sync v0.20.0
	golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c
)

require golang.org/x/sys v0.42.0 // indirect


================================================
FILE: go.sum
================================================
github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/yuin/goldmark v1.4.13 h1:fVcFKWvrslecOb/tg+Cc05dkeYx540o0FuFt3nUVDoE=
github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
golang.org/x/mod v0.34.0 h1:xIHgNUUnW6sYkcM5Jleh05DvLOtwc6RitGHbDk4akRI=
golang.org/x/mod v0.34.0/go.mod h1:ykgH52iCZe79kzLLMhyCUzhMci+nQj+0XkbXpNYtVjY=
golang.org/x/net v0.52.0 h1:He/TN1l0e4mmR3QqHMT2Xab3Aj3L9qjbhRm78/6jrW0=
golang.org/x/net v0.52.0/go.mod h1:R1MAz7uMZxVMualyPXb+VaqGSa3LIaUqk0eEt3w36Sw=
golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c h1:6a8FdnNk6bTXBjR4AGKFgUKuo+7GnR3FX5L7CbveeZc=
golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c/go.mod h1:TpUTTEp9frx7rTdLpC9gFG9kdI7zVLFTFFlqaH2Cncw=


================================================
FILE: gopls/README.md
================================================
# `gopls`, the language server for Go

[![PkgGoDev](https://pkg.go.dev/badge/golang.org/x/tools/gopls)](https://pkg.go.dev/golang.org/x/tools/gopls)

`gopls` (pronounced "Go please") is the official [language
server](https://langserver.org) for Go, developed and maintained by
the Go team.
It provides a wide variety of [IDE features](doc/features/)
to any [LSP](https://microsoft.github.io/language-server-protocol/)-compatible
editor.

- Documentation for [users](https://go.dev/gopls)
- Documentation for [contributors](doc/contributing.md)


================================================
FILE: gopls/contributors.txt
================================================
# This list is used to help generate the GitHub handles in the
# contributor shout-out of each gopls release note.
#
# Use a command such as this to convert a range of git commits:
#
# $ join -o 2.2 <(git log --format="format: %aE" gopls/v0.18.1..gopls/v0.19.0-pre.3 | sort -u) \
#               <(grep '^[^#]' ~/w/xtools/gopls/contributors.txt | sort)
#
# Use -v 1 instead of -o 2.2 to detect any missing entries.

acehinnnqru@gmail.com		acehinnnqru
adonovan@google.com 		adonovan
albertofanjul@gmail.com		albfan
alessandro.arzilli@gmail.com 	aarzilli
ashurbekovz23@gmail.com 	ashurbekovz
cuong.manhle.vn@gmail.com       cuonglm
dmitshur@golang.org 		dmitshur
dneil@google.com 		neild
egonelbre@gmail.com 		egonelbre
email@ssnk.in			shashank-priyadarshi
ethan.reesor@gmail.com		firelizzard18
gobot@golang.org		gopherbot
hxjiang@golang.org		h9jiang
imcusg@gmail.com		cuishuang
jacob.b.bailey@gmail.com	jakebailey
jba@google.com                  jba
mkalil@google.com               madelinekalil
mrnk3078@gmail.com		karamaru-alpha
nguyenbao1917@gmail.com		danztran
nick.ripley@datadoghq.com 	nsrip-dd
pjw@google.com 			pjweinb
rfindley@google.com 		findleyr
samthanawalla@google.com 	samthanawalla
sean@liao.dev 			seankhliao
tklauser@distanz.ch 		tklauser
veblomqvist@gmail.com		vikblom
weingartner@google.com		kwjw
xieyuschen@gmail.com		xieyuschen

# GitHub ID unknown:
# - shibinxf@gmail.com


================================================
FILE: gopls/doc/README.md
================================================
See [index.md](index.md).


================================================
FILE: gopls/doc/advanced.md
================================================
---
title: "Gopls: Advanced topics"
---

This documentation is for advanced `gopls` users, who may want to test
unreleased versions or try out special features.

## Installing unreleased versions

To get a specific version of `gopls` (for example, to test a prerelease
version), run:

```sh
$ go install golang.org/x/tools/gopls@vX.Y.Z
```

Where `vX.Y.Z` is the desired version.

### Unstable versions

To update `gopls` to the latest **unstable** version, use the following
commands.

```sh
# Create an empty go.mod file, only for tracking requirements.
cd $(mktemp -d)
go mod init gopls-unstable

# Use 'go get' to add requirements and to ensure they work together.
go get -d golang.org/x/tools/gopls@master golang.org/x/tools@master

go install golang.org/x/tools/gopls
```

## Working on the Go source distribution

If you are working on the [Go project] itself, the `go` command that `gopls`
invokes will have to correspond to the version of the source you are working
on. That is, if you have checked out the Go project to `$HOME/go-tip`, your
`go` command should be the `$HOME/go-tip/bin/go` executable that you built
with `make.bash` or equivalent.

You can achieve this by adding the right version of `go` to your `PATH`
(`export PATH=$HOME/go-tip/bin:$PATH` on Unix systems) or by configuring your
editor.

To work on both `std` and `cmd` simultaneously, add a `go.work` file to
`GOROOT/src`:

```
cd $(go env GOROOT)/src
go work init . cmd
```

Note that you must work inside the `GOROOT/src` subdirectory, as the `go`
command does not recognize `go.work` files in a parent of `GOROOT/src`
(https://go.dev/issue/59429).

[Go project]: https://go.googlesource.com/go


================================================
FILE: gopls/doc/analyzers.md
================================================
---
title: "Gopls: Analyzers"
---

<!-- No Table of Contents: GitHub's Markdown renderer synthesizes it. -->

Gopls contains a driver for pluggable, modular static
[analyzers](https://pkg.go.dev/golang.org/x/tools/go/analysis#hdr-Analyzer),
such as those used by [go vet](https://pkg.go.dev/cmd/vet).

Most analyzers report mistakes in your code;
some suggest "quick fixes" that can be directly applied in your editor.
Every time you edit your code, gopls re-runs its analyzers.
Analyzer diagnostics help you detect bugs sooner,
before you run your tests, or even before you save your files.

This document describes the suite of analyzers available in gopls,
which aggregates analyzers from a variety of sources:

- all the usual bug-finding analyzers from the `go vet` suite (e.g. `printf`; see [`go tool vet help`](https://pkg.go.dev/cmd/vet) for the complete list);
- a number of analyzers with more substantial dependencies that prevent them from being used in `go vet` (e.g. `nilness`);
- analyzers that augment compilation errors by suggesting quick fixes to common mistakes (e.g. `fillreturns`); and
- a handful of analyzers that suggest possible style improvements (e.g. `simplifyrange`).

To enable or disable analyzers, use the [analyses](settings.md#analyses) setting.

In addition, gopls includes the [`staticcheck` suite](https://staticcheck.dev/docs/checks).
When the [`staticcheck`](settings.md#staticcheck`) boolean option is
unset, slightly more than half of these analyzers are enabled by
default; this subset has been chosen for precision and efficiency. Set
`staticcheck` to `true` to enable the complete set, or to `false` to
disable the complete set.

Staticcheck analyzers, like all other analyzers, can be explicitly
enabled or disabled using the `analyzers` configuration setting; this
setting takes precedence over the `staticcheck` setting, so,
regardless of what value of `staticcheck` you use (true/false/unset),
you can make adjustments to your preferred set of analyzers.


<!-- BEGIN Analyzers: DO NOT MANUALLY EDIT THIS SECTION -->
<a id='QF1001'></a>
## `QF1001`: Apply De Morgan's law

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1001": true}`.

Package documentation: [QF1001](https://staticcheck.dev/docs/checks/#QF1001)

<a id='QF1002'></a>
## `QF1002`: Convert untagged switch to tagged switch

An untagged switch that compares a single variable against a series of values can be replaced with a tagged switch.

Before:

	switch {
	case x == 1 || x == 2, x == 3:
	    ...
	case x == 4:
	    ...
	default:
	    ...
	}

After:

	switch x {
	case 1, 2, 3:
	    ...
	case 4:
	    ...
	default:
	    ...
	}

Available since

	2021.1


Default: on.

Package documentation: [QF1002](https://staticcheck.dev/docs/checks/#QF1002)

<a id='QF1003'></a>
## `QF1003`: Convert if/else-if chain to tagged switch

A series of if/else-if checks comparing the same variable against values can be replaced with a tagged switch.

Before:

	if x == 1 || x == 2 {
	    ...
	} else if x == 3 {
	    ...
	} else {
	    ...
	}

After:

	switch x {
	case 1, 2:
	    ...
	case 3:
	    ...
	default:
	    ...
	}

Available since

	2021.1


Default: on.

Package documentation: [QF1003](https://staticcheck.dev/docs/checks/#QF1003)

<a id='QF1004'></a>
## `QF1004`: Use strings.ReplaceAll instead of strings.Replace with n == -1

Available since

	2021.1


Default: on.

Package documentation: [QF1004](https://staticcheck.dev/docs/checks/#QF1004)

<a id='QF1005'></a>
## `QF1005`: Expand call to math.Pow

Some uses of math.Pow can be simplified to basic multiplication.

Before:

	math.Pow(x, 2)

After:

	x * x

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1005": true}`.

Package documentation: [QF1005](https://staticcheck.dev/docs/checks/#QF1005)

<a id='QF1006'></a>
## `QF1006`: Lift if+break into loop condition

Before:

	for {
	    if done {
	        break
	    }
	    ...
	}

After:

	for !done {
	    ...
	}

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1006": true}`.

Package documentation: [QF1006](https://staticcheck.dev/docs/checks/#QF1006)

<a id='QF1007'></a>
## `QF1007`: Merge conditional assignment into variable declaration

Before:

	x := false
	if someCondition {
	    x = true
	}

After:

	x := someCondition

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1007": true}`.

Package documentation: [QF1007](https://staticcheck.dev/docs/checks/#QF1007)

<a id='QF1008'></a>
## `QF1008`: Omit embedded fields from selector expression

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1008": true}`.

Package documentation: [QF1008](https://staticcheck.dev/docs/checks/#QF1008)

<a id='QF1009'></a>
## `QF1009`: Use time.Time.Equal instead of == operator

Available since

	2021.1


Default: on.

Package documentation: [QF1009](https://staticcheck.dev/docs/checks/#QF1009)

<a id='QF1010'></a>
## `QF1010`: Convert slice of bytes to string when printing it

Available since

	2021.1


Default: on.

Package documentation: [QF1010](https://staticcheck.dev/docs/checks/#QF1010)

<a id='QF1011'></a>
## `QF1011`: Omit redundant type from variable declaration

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"QF1011": true}`.

Package documentation: [QF1011](https://staticcheck.dev/docs/checks/#)

<a id='QF1012'></a>
## `QF1012`: Use fmt.Fprintf(x, ...) instead of x.Write(fmt.Sprintf(...))

Available since

	2022.1


Default: on.

Package documentation: [QF1012](https://staticcheck.dev/docs/checks/#QF1012)

<a id='S1000'></a>
## `S1000`: Use plain channel send or receive instead of single-case select

Select statements with a single case can be replaced with a simple send or receive.

Before:

	select {
	case x := <-ch:
	    fmt.Println(x)
	}

After:

	x := <-ch
	fmt.Println(x)

Available since

	2017.1


Default: on.

Package documentation: [S1000](https://staticcheck.dev/docs/checks/#S1000)

<a id='S1001'></a>
## `S1001`: Replace for loop with call to copy

Use copy() for copying elements from one slice to another. For arrays of identical size, you can use simple assignment.

Before:

	for i, x := range src {
	    dst[i] = x
	}

After:

	copy(dst, src)

Available since

	2017.1


Default: on.

Package documentation: [S1001](https://staticcheck.dev/docs/checks/#S1001)

<a id='S1002'></a>
## `S1002`: Omit comparison with boolean constant

Before:

	if x == true {}

After:

	if x {}

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1002": true}`.

Package documentation: [S1002](https://staticcheck.dev/docs/checks/#S1002)

<a id='S1003'></a>
## `S1003`: Replace call to strings.Index with strings.Contains

Before:

	if strings.Index(x, y) != -1 {}

After:

	if strings.Contains(x, y) {}

Available since

	2017.1


Default: on.

Package documentation: [S1003](https://staticcheck.dev/docs/checks/#S1003)

<a id='S1004'></a>
## `S1004`: Replace call to bytes.Compare with bytes.Equal

Before:

	if bytes.Compare(x, y) == 0 {}

After:

	if bytes.Equal(x, y) {}

Available since

	2017.1


Default: on.

Package documentation: [S1004](https://staticcheck.dev/docs/checks/#S1004)

<a id='S1005'></a>
## `S1005`: Drop unnecessary use of the blank identifier

In many cases, assigning to the blank identifier is unnecessary.

Before:

	for _ = range s {}
	x, _ = someMap[key]
	_ = <-ch

After:

	for range s{}
	x = someMap[key]
	<-ch

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1005": true}`.

Package documentation: [S1005](https://staticcheck.dev/docs/checks/#S1005)

<a id='S1006'></a>
## `S1006`: Use 'for { ... }' for infinite loops

For infinite loops, using for { ... } is the most idiomatic choice.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1006": true}`.

Package documentation: [S1006](https://staticcheck.dev/docs/checks/#S1006)

<a id='S1007'></a>
## `S1007`: Simplify regular expression by using raw string literal

Raw string literals use backticks instead of quotation marks and do not support any escape sequences. This means that the backslash can be used freely, without the need of escaping.

Since regular expressions have their own escape sequences, raw strings can improve their readability.

Before:

	regexp.Compile("\\A(\\w+) profile: total \\d+\\n\\z")

After:

	regexp.Compile(`\A(\w+) profile: total \d+\n\z`)

Available since

	2017.1


Default: on.

Package documentation: [S1007](https://staticcheck.dev/docs/checks/#S1007)

<a id='S1008'></a>
## `S1008`: Simplify returning boolean expression

Before:

	if <expr> {
	    return true
	}
	return false

After:

	return <expr>

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1008": true}`.

Package documentation: [S1008](https://staticcheck.dev/docs/checks/#S1008)

<a id='S1009'></a>
## `S1009`: Omit redundant nil check on slices, maps, and channels

The len function is defined for all slices, maps, and channels, even nil ones, which have a length of zero. It is not necessary to check for nil before checking that their length is not zero.

Before:

	if x != nil && len(x) != 0 {}

After:

	if len(x) != 0 {}

Available since

	2017.1


Default: on.

Package documentation: [S1009](https://staticcheck.dev/docs/checks/#S1009)

<a id='S1010'></a>
## `S1010`: Omit default slice index

When slicing, the second index defaults to the length of the value, making s\[n:len(s)] and s\[n:] equivalent.

Available since

	2017.1


Default: on.

Package documentation: [S1010](https://staticcheck.dev/docs/checks/#S1010)

<a id='S1011'></a>
## `S1011`: Use a single append to concatenate two slices

Before:

	for _, e := range y {
	    x = append(x, e)
	}

	for i := range y {
	    x = append(x, y[i])
	}

	for i := range y {
	    v := y[i]
	    x = append(x, v)
	}

After:

	x = append(x, y...)
	x = append(x, y...)
	x = append(x, y...)

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1011": true}`.

Package documentation: [S1011](https://staticcheck.dev/docs/checks/#S1011)

<a id='S1012'></a>
## `S1012`: Replace time.Now().Sub(x) with time.Since(x)

The time.Since helper has the same effect as using time.Now().Sub(x) but is easier to read.

Before:

	time.Now().Sub(x)

After:

	time.Since(x)

Available since

	2017.1


Default: on.

Package documentation: [S1012](https://staticcheck.dev/docs/checks/#S1012)

<a id='S1016'></a>
## `S1016`: Use a type conversion instead of manually copying struct fields

Two struct types with identical fields can be converted between each other. In older versions of Go, the fields had to have identical struct tags. Since Go 1.8, however, struct tags are ignored during conversions. It is thus not necessary to manually copy every field individually.

Before:

	var x T1
	y := T2{
	    Field1: x.Field1,
	    Field2: x.Field2,
	}

After:

	var x T1
	y := T2(x)

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1016": true}`.

Package documentation: [S1016](https://staticcheck.dev/docs/checks/#S1016)

<a id='S1017'></a>
## `S1017`: Replace manual trimming with strings.TrimPrefix

Instead of using strings.HasPrefix and manual slicing, use the strings.TrimPrefix function. If the string doesn't start with the prefix, the original string will be returned. Using strings.TrimPrefix reduces complexity, and avoids common bugs, such as off-by-one mistakes.

Before:

	if strings.HasPrefix(str, prefix) {
	    str = str[len(prefix):]
	}

After:

	str = strings.TrimPrefix(str, prefix)

Available since

	2017.1


Default: on.

Package documentation: [S1017](https://staticcheck.dev/docs/checks/#S1017)

<a id='S1018'></a>
## `S1018`: Use 'copy' for sliding elements

copy() permits using the same source and destination slice, even with overlapping ranges. This makes it ideal for sliding elements in a slice.

Before:

	for i := 0; i < n; i++ {
	    bs[i] = bs[offset+i]
	}

After:

	copy(bs[:n], bs[offset:])

Available since

	2017.1


Default: on.

Package documentation: [S1018](https://staticcheck.dev/docs/checks/#S1018)

<a id='S1019'></a>
## `S1019`: Simplify 'make' call by omitting redundant arguments

The 'make' function has default values for the length and capacity arguments. For channels, the length defaults to zero, and for slices, the capacity defaults to the length.

Available since

	2017.1


Default: on.

Package documentation: [S1019](https://staticcheck.dev/docs/checks/#S1019)

<a id='S1020'></a>
## `S1020`: Omit redundant nil check in type assertion

Before:

	if _, ok := i.(T); ok && i != nil {}

After:

	if _, ok := i.(T); ok {}

Available since

	2017.1


Default: on.

Package documentation: [S1020](https://staticcheck.dev/docs/checks/#S1020)

<a id='S1021'></a>
## `S1021`: Merge variable declaration and assignment

Before:

	var x uint
	x = 1

After:

	var x uint = 1

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1021": true}`.

Package documentation: [S1021](https://staticcheck.dev/docs/checks/#S1021)

<a id='S1023'></a>
## `S1023`: Omit redundant control flow

Functions that have no return value do not need a return statement as the final statement of the function.

Switches in Go do not have automatic fallthrough, unlike languages like C. It is not necessary to have a break statement as the final statement in a case block.

Available since

	2017.1


Default: on.

Package documentation: [S1023](https://staticcheck.dev/docs/checks/#S1023)

<a id='S1024'></a>
## `S1024`: Replace x.Sub(time.Now()) with time.Until(x)

The time.Until helper has the same effect as using x.Sub(time.Now()) but is easier to read.

Before:

	x.Sub(time.Now())

After:

	time.Until(x)

Available since

	2017.1


Default: on.

Package documentation: [S1024](https://staticcheck.dev/docs/checks/#S1024)

<a id='S1025'></a>
## `S1025`: Don't use fmt.Sprintf("%s", x) unnecessarily

In many instances, there are easier and more efficient ways of getting a value's string representation. Whenever a value's underlying type is a string already, or the type has a String method, they should be used directly.

Given the following shared definitions

	type T1 string
	type T2 int

	func (T2) String() string { return "Hello, world" }

	var x string
	var y T1
	var z T2

we can simplify

	fmt.Sprintf("%s", x)
	fmt.Sprintf("%s", y)
	fmt.Sprintf("%s", z)

to

	x
	string(y)
	z.String()

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1025": true}`.

Package documentation: [S1025](https://staticcheck.dev/docs/checks/#S1025)

<a id='S1028'></a>
## `S1028`: Simplify error construction with fmt.Errorf

Before:

	errors.New(fmt.Sprintf(...))

After:

	fmt.Errorf(...)

Available since

	2017.1


Default: on.

Package documentation: [S1028](https://staticcheck.dev/docs/checks/#S1028)

<a id='S1029'></a>
## `S1029`: Range over the string directly

Ranging over a string will yield byte offsets and runes. If the offset isn't used, this is functionally equivalent to converting the string to a slice of runes and ranging over that. Ranging directly over the string will be more performant, however, as it avoids allocating a new slice, the size of which depends on the length of the string.

Before:

	for _, r := range []rune(s) {}

After:

	for _, r := range s {}

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"S1029": true}`.

Package documentation: [S1029](https://staticcheck.dev/docs/checks/#S1029)

<a id='S1030'></a>
## `S1030`: Use bytes.Buffer.String or bytes.Buffer.Bytes

bytes.Buffer has both a String and a Bytes method. It is almost never necessary to use string(buf.Bytes()) or \[]byte(buf.String()) – simply use the other method.

The only exception to this are map lookups. Due to a compiler optimization, m\[string(buf.Bytes())] is more efficient than m\[buf.String()].

Available since

	2017.1


Default: on.

Package documentation: [S1030](https://staticcheck.dev/docs/checks/#S1030)

<a id='S1031'></a>
## `S1031`: Omit redundant nil check around loop

You can use range on nil slices and maps, the loop will simply never execute. This makes an additional nil check around the loop unnecessary.

Before:

	if s != nil {
	    for _, x := range s {
	        ...
	    }
	}

After:

	for _, x := range s {
	    ...
	}

Available since

	2017.1


Default: on.

Package documentation: [S1031](https://staticcheck.dev/docs/checks/#S1031)

<a id='S1032'></a>
## `S1032`: Use sort.Ints(x), sort.Float64s(x), and sort.Strings(x)

The sort.Ints, sort.Float64s and sort.Strings functions are easier to read than sort.Sort(sort.IntSlice(x)), sort.Sort(sort.Float64Slice(x)) and sort.Sort(sort.StringSlice(x)).

Before:

	sort.Sort(sort.StringSlice(x))

After:

	sort.Strings(x)

Available since

	2019.1


Default: on.

Package documentation: [S1032](https://staticcheck.dev/docs/checks/#S1032)

<a id='S1033'></a>
## `S1033`: Unnecessary guard around call to 'delete'

Calling delete on a nil map is a no-op.

Available since

	2019.2


Default: on.

Package documentation: [S1033](https://staticcheck.dev/docs/checks/#S1033)

<a id='S1034'></a>
## `S1034`: Use result of type assertion to simplify cases

Available since

	2019.2


Default: on.

Package documentation: [S1034](https://staticcheck.dev/docs/checks/#S1034)

<a id='S1035'></a>
## `S1035`: Redundant call to net/http.CanonicalHeaderKey in method call on net/http.Header

The methods on net/http.Header, namely Add, Del, Get and Set, already canonicalize the given header name.

Available since

	2020.1


Default: on.

Package documentation: [S1035](https://staticcheck.dev/docs/checks/#S1035)

<a id='S1036'></a>
## `S1036`: Unnecessary guard around map access

When accessing a map key that doesn't exist yet, one receives a zero value. Often, the zero value is a suitable value, for example when using append or doing integer math.

The following

	if _, ok := m["foo"]; ok {
	    m["foo"] = append(m["foo"], "bar")
	} else {
	    m["foo"] = []string{"bar"}
	}

can be simplified to

	m["foo"] = append(m["foo"], "bar")

and

	if _, ok := m2["k"]; ok {
	    m2["k"] += 4
	} else {
	    m2["k"] = 4
	}

can be simplified to

	m["k"] += 4

Available since

	2020.1


Default: on.

Package documentation: [S1036](https://staticcheck.dev/docs/checks/#S1036)

<a id='S1037'></a>
## `S1037`: Elaborate way of sleeping

Using a select statement with a single case receiving from the result of time.After is a very elaborate way of sleeping that can much simpler be expressed with a simple call to time.Sleep.

Available since

	2020.1


Default: on.

Package documentation: [S1037](https://staticcheck.dev/docs/checks/#S1037)

<a id='S1038'></a>
## `S1038`: Unnecessarily complex way of printing formatted string

Instead of using fmt.Print(fmt.Sprintf(...)), one can use fmt.Printf(...).

Available since

	2020.1


Default: on.

Package documentation: [S1038](https://staticcheck.dev/docs/checks/#S1038)

<a id='S1039'></a>
## `S1039`: Unnecessary use of fmt.Sprint

Calling fmt.Sprint with a single string argument is unnecessary and identical to using the string directly.

Available since

	2020.1


Default: on.

Package documentation: [S1039](https://staticcheck.dev/docs/checks/#S1039)

<a id='S1040'></a>
## `S1040`: Type assertion to current type

The type assertion x.(SomeInterface), when x already has type SomeInterface, can only fail if x is nil. Usually, this is left-over code from when x had a different type and you can safely delete the type assertion. If you want to check that x is not nil, consider being explicit and using an actual if x == nil comparison instead of relying on the type assertion panicking.

Available since

	2021.1


Default: on.

Package documentation: [S1040](https://staticcheck.dev/docs/checks/#S1040)

<a id='SA1000'></a>
## `SA1000`: Invalid regular expression

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1000": true}`.

Package documentation: [SA1000](https://staticcheck.dev/docs/checks/#SA1000)

<a id='SA1001'></a>
## `SA1001`: Invalid template

Available since

	2017.1


Default: on.

Package documentation: [SA1001](https://staticcheck.dev/docs/checks/#SA1001)

<a id='SA1002'></a>
## `SA1002`: Invalid format in time.Parse

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1002": true}`.

Package documentation: [SA1002](https://staticcheck.dev/docs/checks/#SA1002)

<a id='SA1003'></a>
## `SA1003`: Unsupported argument to functions in encoding/binary

The encoding/binary package can only serialize types with known sizes. This precludes the use of the int and uint types, as their sizes differ on different architectures. Furthermore, it doesn't support serializing maps, channels, strings, or functions.

Before Go 1.8, bool wasn't supported, either.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1003": true}`.

Package documentation: [SA1003](https://staticcheck.dev/docs/checks/#SA1003)

<a id='SA1004'></a>
## `SA1004`: Suspiciously small untyped constant in time.Sleep

The time.Sleep function takes a time.Duration as its only argument. Durations are expressed in nanoseconds. Thus, calling time.Sleep(1) will sleep for 1 nanosecond. This is a common source of bugs, as sleep functions in other languages often accept seconds or milliseconds.

The time package provides constants such as time.Second to express large durations. These can be combined with arithmetic to express arbitrary durations, for example 5 \* time.Second for 5 seconds.

If you truly meant to sleep for a tiny amount of time, use n \* time.Nanosecond to signal to Staticcheck that you did mean to sleep for some amount of nanoseconds.

Available since

	2017.1


Default: on.

Package documentation: [SA1004](https://staticcheck.dev/docs/checks/#SA1004)

<a id='SA1005'></a>
## `SA1005`: Invalid first argument to exec.Command

os/exec runs programs directly (using variants of the fork and exec system calls on Unix systems). This shouldn't be confused with running a command in a shell. The shell will allow for features such as input redirection, pipes, and general scripting. The shell is also responsible for splitting the user's input into a program name and its arguments. For example, the equivalent to

	ls / /tmp

would be

	exec.Command("ls", "/", "/tmp")

If you want to run a command in a shell, consider using something like the following – but be aware that not all systems, particularly Windows, will have a /bin/sh program:

	exec.Command("/bin/sh", "-c", "ls | grep Awesome")

Available since

	2017.1


Default: on.

Package documentation: [SA1005](https://staticcheck.dev/docs/checks/#SA1005)

<a id='SA1007'></a>
## `SA1007`: Invalid URL in net/url.Parse

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1007": true}`.

Package documentation: [SA1007](https://staticcheck.dev/docs/checks/#SA1007)

<a id='SA1008'></a>
## `SA1008`: Non-canonical key in http.Header map

Keys in http.Header maps are canonical, meaning they follow a specific combination of uppercase and lowercase letters. Methods such as http.Header.Add and http.Header.Del convert inputs into this canonical form before manipulating the map.

When manipulating http.Header maps directly, as opposed to using the provided methods, care should be taken to stick to canonical form in order to avoid inconsistencies. The following piece of code demonstrates one such inconsistency:

	h := http.Header{}
	h["etag"] = []string{"1234"}
	h.Add("etag", "5678")
	fmt.Println(h)

	// Output:
	// map[Etag:[5678] etag:[1234]]

The easiest way of obtaining the canonical form of a key is to use http.CanonicalHeaderKey.

Available since

	2017.1


Default: on.

Package documentation: [SA1008](https://staticcheck.dev/docs/checks/#SA1008)

<a id='SA1010'></a>
## `SA1010`: (*regexp.Regexp).FindAll called with n == 0, which will always return zero results

If n >= 0, the function returns at most n matches/submatches. To return all results, specify a negative number.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1010": true}`.

Package documentation: [SA1010](https://staticcheck.dev/docs/checks/#SA1010)

<a id='SA1011'></a>
## `SA1011`: Various methods in the 'strings' package expect valid UTF-8, but invalid input is provided

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1011": true}`.

Package documentation: [SA1011](https://staticcheck.dev/docs/checks/#SA1011)

<a id='SA1012'></a>
## `SA1012`: A nil context.Context is being passed to a function, consider using context.TODO instead

Available since

	2017.1


Default: on.

Package documentation: [SA1012](https://staticcheck.dev/docs/checks/#SA1012)

<a id='SA1013'></a>
## `SA1013`: io.Seeker.Seek is being called with the whence constant as the first argument, but it should be the second

Available since

	2017.1


Default: on.

Package documentation: [SA1013](https://staticcheck.dev/docs/checks/#SA1013)

<a id='SA1014'></a>
## `SA1014`: Non-pointer value passed to Unmarshal or Decode

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1014": true}`.

Package documentation: [SA1014](https://staticcheck.dev/docs/checks/#SA1014)

<a id='SA1015'></a>
## `SA1015`: Using time.Tick in a way that will leak. Consider using time.NewTicker, and only use time.Tick in tests, commands and endless functions

Before Go 1.23, time.Tickers had to be closed to be able to be garbage collected. Since time.Tick doesn't make it possible to close the underlying ticker, using it repeatedly would leak memory.

Go 1.23 fixes this by allowing tickers to be collected even if they weren't closed.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1015": true}`.

Package documentation: [SA1015](https://staticcheck.dev/docs/checks/#SA1015)

<a id='SA1016'></a>
## `SA1016`: Trapping a signal that cannot be trapped

Not all signals can be intercepted by a process. Specifically, on UNIX-like systems, the syscall.SIGKILL and syscall.SIGSTOP signals are never passed to the process, but instead handled directly by the kernel. It is therefore pointless to try and handle these signals.

Available since

	2017.1


Default: on.

Package documentation: [SA1016](https://staticcheck.dev/docs/checks/#SA1016)

<a id='SA1017'></a>
## `SA1017`: Channels used with os/signal.Notify should be buffered

The os/signal package uses non-blocking channel sends when delivering signals. If the receiving end of the channel isn't ready and the channel is either unbuffered or full, the signal will be dropped. To avoid missing signals, the channel should be buffered and of the appropriate size. For a channel used for notification of just one signal value, a buffer of size 1 is sufficient.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1017": true}`.

Package documentation: [SA1017](https://staticcheck.dev/docs/checks/#SA1017)

<a id='SA1018'></a>
## `SA1018`: strings.Replace called with n == 0, which does nothing

With n == 0, zero instances will be replaced. To replace all instances, use a negative number, or use strings.ReplaceAll.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1018": true}`.

Package documentation: [SA1018](https://staticcheck.dev/docs/checks/#SA1018)

<a id='SA1020'></a>
## `SA1020`: Using an invalid host:port pair with a net.Listen-related function

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1020": true}`.

Package documentation: [SA1020](https://staticcheck.dev/docs/checks/#SA1020)

<a id='SA1021'></a>
## `SA1021`: Using bytes.Equal to compare two net.IP

A net.IP stores an IPv4 or IPv6 address as a slice of bytes. The length of the slice for an IPv4 address, however, can be either 4 or 16 bytes long, using different ways of representing IPv4 addresses. In order to correctly compare two net.IPs, the net.IP.Equal method should be used, as it takes both representations into account.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1021": true}`.

Package documentation: [SA1021](https://staticcheck.dev/docs/checks/#SA1021)

<a id='SA1023'></a>
## `SA1023`: Modifying the buffer in an io.Writer implementation

Write must not modify the slice data, even temporarily.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1023": true}`.

Package documentation: [SA1023](https://staticcheck.dev/docs/checks/#SA1023)

<a id='SA1024'></a>
## `SA1024`: A string cutset contains duplicate characters

The strings.TrimLeft and strings.TrimRight functions take cutsets, not prefixes. A cutset is treated as a set of characters to remove from a string. For example,

	strings.TrimLeft("42133word", "1234")

will result in the string "word" – any characters that are 1, 2, 3 or 4 are cut from the left of the string.

In order to remove one string from another, use strings.TrimPrefix instead.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA1024": true}`.

Package documentation: [SA1024](https://staticcheck.dev/docs/checks/#SA1024)

<a id='SA1025'></a>
## `SA1025`: It is not possible to use (*time.Timer).Reset's return value correctly

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"SA1025": true}`.

Package documentation: [SA1025](https://staticcheck.dev/docs/checks/#SA1025)

<a id='SA1026'></a>
## `SA1026`: Cannot marshal channels or functions

Available since

	2019.2


Default: off. Enable by setting `"analyses": {"SA1026": true}`.

Package documentation: [SA1026](https://staticcheck.dev/docs/checks/#SA1026)

<a id='SA1027'></a>
## `SA1027`: Atomic access to 64-bit variable must be 64-bit aligned

On ARM, x86-32, and 32-bit MIPS, it is the caller's responsibility to arrange for 64-bit alignment of 64-bit words accessed atomically. The first word in a variable or in an allocated struct, array, or slice can be relied upon to be 64-bit aligned.

You can use the structlayout tool to inspect the alignment of fields in a struct.

Available since

	2019.2


Default: off. Enable by setting `"analyses": {"SA1027": true}`.

Package documentation: [SA1027](https://staticcheck.dev/docs/checks/#SA1027)

<a id='SA1028'></a>
## `SA1028`: sort.Slice can only be used on slices

The first argument of sort.Slice must be a slice.

Available since

	2020.1


Default: off. Enable by setting `"analyses": {"SA1028": true}`.

Package documentation: [SA1028](https://staticcheck.dev/docs/checks/#SA1028)

<a id='SA1029'></a>
## `SA1029`: Inappropriate key in call to context.WithValue

The provided key must be comparable and should not be of type string or any other built-in type to avoid collisions between packages using context. Users of WithValue should define their own types for keys.

To avoid allocating when assigning to an interface{}, context keys often have concrete type struct{}. Alternatively, exported context key variables' static type should be a pointer or interface.

Available since

	2020.1


Default: off. Enable by setting `"analyses": {"SA1029": true}`.

Package documentation: [SA1029](https://staticcheck.dev/docs/checks/#SA1029)

<a id='SA1030'></a>
## `SA1030`: Invalid argument in call to a strconv function

This check validates the format, number base and bit size arguments of the various parsing and formatting functions in strconv.

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"SA1030": true}`.

Package documentation: [SA1030](https://staticcheck.dev/docs/checks/#SA1030)

<a id='SA1031'></a>
## `SA1031`: Overlapping byte slices passed to an encoder

In an encoding function of the form Encode(dst, src), dst and src were found to reference the same memory. This can result in src bytes being overwritten before they are read, when the encoder writes more than one byte per src byte.

Available since

	2024.1


Default: off. Enable by setting `"analyses": {"SA1031": true}`.

Package documentation: [SA1031](https://staticcheck.dev/docs/checks/#SA1031)

<a id='SA1032'></a>
## `SA1032`: Wrong order of arguments to errors.Is

The first argument of the function errors.Is is the error that we have and the second argument is the error we're trying to match against. For example:

	if errors.Is(err, io.EOF) { ... }

This check detects some cases where the two arguments have been swapped. It flags any calls where the first argument is referring to a package-level error variable, such as

	if errors.Is(io.EOF, err) { /* this is wrong */ }

Available since

	2024.1


Default: off. Enable by setting `"analyses": {"SA1032": true}`.

Package documentation: [SA1032](https://staticcheck.dev/docs/checks/#SA1032)

<a id='SA2001'></a>
## `SA2001`: Empty critical section, did you mean to defer the unlock?

Empty critical sections of the kind

	mu.Lock()
	mu.Unlock()

are very often a typo, and the following was intended instead:

	mu.Lock()
	defer mu.Unlock()

Do note that sometimes empty critical sections can be useful, as a form of signaling to wait on another goroutine. Many times, there are simpler ways of achieving the same effect. When that isn't the case, the code should be amply commented to avoid confusion. Combining such comments with a //lint:ignore directive can be used to suppress this rare false positive.

Available since

	2017.1


Default: on.

Package documentation: [SA2001](https://staticcheck.dev/docs/checks/#SA2001)

<a id='SA2002'></a>
## `SA2002`: Called testing.T.FailNow or SkipNow in a goroutine, which isn't allowed

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA2002": true}`.

Package documentation: [SA2002](https://staticcheck.dev/docs/checks/#SA2002)

<a id='SA2003'></a>
## `SA2003`: Deferred Lock right after locking, likely meant to defer Unlock instead

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA2003": true}`.

Package documentation: [SA2003](https://staticcheck.dev/docs/checks/#SA2003)

<a id='SA3000'></a>
## `SA3000`: TestMain doesn't call os.Exit, hiding test failures

Test executables (and in turn 'go test') exit with a non-zero status code if any tests failed. When specifying your own TestMain function, it is your responsibility to arrange for this, by calling os.Exit with the correct code. The correct code is returned by (\*testing.M).Run, so the usual way of implementing TestMain is to end it with os.Exit(m.Run()).

Available since

	2017.1


Default: on.

Package documentation: [SA3000](https://staticcheck.dev/docs/checks/#SA3000)

<a id='SA3001'></a>
## `SA3001`: Assigning to b.N in benchmarks distorts the results

The testing package dynamically sets b.N to improve the reliability of benchmarks and uses it in computations to determine the duration of a single operation. Benchmark code must not alter b.N as this would falsify results.

Available since

	2017.1


Default: on.

Package documentation: [SA3001](https://staticcheck.dev/docs/checks/#SA3001)

<a id='SA4000'></a>
## `SA4000`: Binary operator has identical expressions on both sides

Available since

	2017.1


Default: on.

Package documentation: [SA4000](https://staticcheck.dev/docs/checks/#SA4000)

<a id='SA4001'></a>
## `SA4001`: &*x gets simplified to x, it does not copy x

Available since

	2017.1


Default: on.

Package documentation: [SA4001](https://staticcheck.dev/docs/checks/#SA4001)

<a id='SA4003'></a>
## `SA4003`: Comparing unsigned values against negative values is pointless

Available since

	2017.1


Default: on.

Package documentation: [SA4003](https://staticcheck.dev/docs/checks/#SA4003)

<a id='SA4004'></a>
## `SA4004`: The loop exits unconditionally after one iteration

Available since

	2017.1


Default: on.

Package documentation: [SA4004](https://staticcheck.dev/docs/checks/#SA4004)

<a id='SA4005'></a>
## `SA4005`: Field assignment that will never be observed. Did you mean to use a pointer receiver?

Available since

	2021.1


Default: off. Enable by setting `"analyses": {"SA4005": true}`.

Package documentation: [SA4005](https://staticcheck.dev/docs/checks/#SA4005)

<a id='SA4006'></a>
## `SA4006`: A value assigned to a variable is never read before being overwritten. Forgotten error check or dead code?

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4006": true}`.

Package documentation: [SA4006](https://staticcheck.dev/docs/checks/#SA4006)

<a id='SA4008'></a>
## `SA4008`: The variable in the loop condition never changes, are you incrementing the wrong variable?

For example:

	for i := 0; i < 10; j++ { ... }

This may also occur when a loop can only execute once because of unconditional control flow that terminates the loop. For example, when a loop body contains an unconditional break, return, or panic:

	func f() {
		panic("oops")
	}
	func g() {
		for i := 0; i < 10; i++ {
			// f unconditionally calls panic, which means "i" is
			// never incremented.
			f()
		}
	}

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4008": true}`.

Package documentation: [SA4008](https://staticcheck.dev/docs/checks/#SA4008)

<a id='SA4009'></a>
## `SA4009`: A function argument is overwritten before its first use

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4009": true}`.

Package documentation: [SA4009](https://staticcheck.dev/docs/checks/#SA4009)

<a id='SA4010'></a>
## `SA4010`: The result of append will never be observed anywhere

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4010": true}`.

Package documentation: [SA4010](https://staticcheck.dev/docs/checks/#SA4010)

<a id='SA4011'></a>
## `SA4011`: Break statement with no effect. Did you mean to break out of an outer loop?

Available since

	2017.1


Default: on.

Package documentation: [SA4011](https://staticcheck.dev/docs/checks/#SA4011)

<a id='SA4012'></a>
## `SA4012`: Comparing a value against NaN even though no value is equal to NaN

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4012": true}`.

Package documentation: [SA4012](https://staticcheck.dev/docs/checks/#SA4012)

<a id='SA4013'></a>
## `SA4013`: Negating a boolean twice (!!b) is the same as writing b. This is either redundant, or a typo.

Available since

	2017.1


Default: on.

Package documentation: [SA4013](https://staticcheck.dev/docs/checks/#SA4013)

<a id='SA4014'></a>
## `SA4014`: An if/else if chain has repeated conditions and no side-effects; if the condition didn't match the first time, it won't match the second time, either

Available since

	2017.1


Default: on.

Package documentation: [SA4014](https://staticcheck.dev/docs/checks/#SA4014)

<a id='SA4015'></a>
## `SA4015`: Calling functions like math.Ceil on floats converted from integers doesn't do anything useful

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4015": true}`.

Package documentation: [SA4015](https://staticcheck.dev/docs/checks/#SA4015)

<a id='SA4016'></a>
## `SA4016`: Certain bitwise operations, such as x ^ 0, do not do anything useful

Available since

	2017.1


Default: on.

Package documentation: [SA4016](https://staticcheck.dev/docs/checks/#SA4016)

<a id='SA4017'></a>
## `SA4017`: Discarding the return values of a function without side effects, making the call pointless

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4017": true}`.

Package documentation: [SA4017](https://staticcheck.dev/docs/checks/#SA4017)

<a id='SA4018'></a>
## `SA4018`: Self-assignment of variables

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA4018": true}`.

Package documentation: [SA4018](https://staticcheck.dev/docs/checks/#SA4018)

<a id='SA4019'></a>
## `SA4019`: Multiple, identical build constraints in the same file

Available since

	2017.1


Default: on.

Package documentation: [SA4019](https://staticcheck.dev/docs/checks/#SA4019)

<a id='SA4020'></a>
## `SA4020`: Unreachable case clause in a type switch

In a type switch like the following

	type T struct{}
	func (T) Read(b []byte) (int, error) { return 0, nil }

	var v any = T{}

	switch v.(type) {
	case io.Reader:
	    // ...
	case T:
	    // unreachable
	}

the second case clause can never be reached because T implements io.Reader and case clauses are evaluated in source order.

Another example:

	type T struct{}
	func (T) Read(b []byte) (int, error) { return 0, nil }
	func (T) Close() error { return nil }

	var v any = T{}

	switch v.(type) {
	case io.Reader:
	    // ...
	case io.ReadCloser:
	    // unreachable
	}

Even though T has a Close method and thus implements io.ReadCloser, io.Reader will always match first. The method set of io.Reader is a subset of io.ReadCloser. Thus it is impossible to match the second case without matching the first case.

### Structurally equivalent interfaces {#hdr-Structurally_equivalent_interfaces}

A special case of the previous example are structurally identical interfaces. Given these declarations

	type T error
	type V error

	func doSomething() error {
	    err, ok := doAnotherThing()
	    if ok {
	        return T(err)
	    }

	    return U(err)
	}

the following type switch will have an unreachable case clause:

	switch doSomething().(type) {
	case T:
	    // ...
	case V:
	    // unreachable
	}

T will always match before V because they are structurally equivalent and therefore doSomething()'s return value implements both.

Available since

	2019.2


Default: on.

Package documentation: [SA4020](https://staticcheck.dev/docs/checks/#SA4020)

<a id='SA4022'></a>
## `SA4022`: Comparing the address of a variable against nil

Code such as 'if &x == nil' is meaningless, because taking the address of a variable always yields a non-nil pointer.

Available since

	2020.1


Default: on.

Package documentation: [SA4022](https://staticcheck.dev/docs/checks/#SA4022)

<a id='SA4023'></a>
## `SA4023`: Impossible comparison of interface value with untyped nil

Under the covers, interfaces are implemented as two elements, a type T and a value V. V is a concrete value such as an int, struct or pointer, never an interface itself, and has type T. For instance, if we store the int value 3 in an interface, the resulting interface value has, schematically, (T=int, V=3). The value V is also known as the interface's dynamic value, since a given interface variable might hold different values V (and corresponding types T) during the execution of the program.

An interface value is nil only if the V and T are both unset, (T=nil, V is not set), In particular, a nil interface will always hold a nil type. If we store a nil pointer of type \*int inside an interface value, the inner type will be \*int regardless of the value of the pointer: (T=\*int, V=nil). Such an interface value will therefore be non-nil even when the pointer value V inside is nil.

This situation can be confusing, and arises when a nil value is stored inside an interface value such as an error return:

	func returnsError() error {
	    var p *MyError = nil
	    if bad() {
	        p = ErrBad
	    }
	    return p // Will always return a non-nil error.
	}

If all goes well, the function returns a nil p, so the return value is an error interface value holding (T=\*MyError, V=nil). This means that if the caller compares the returned error to nil, it will always look as if there was an error even if nothing bad happened. To return a proper nil error to the caller, the function must return an explicit nil:

	func returnsError() error {
	    if bad() {
	        return ErrBad
	    }
	    return nil
	}

It's a good idea for functions that return errors always to use the error type in their signature (as we did above) rather than a concrete type such as \*MyError, to help guarantee the error is created correctly. As an example, os.Open returns an error even though, if not nil, it's always of concrete type \*os.PathError.

Similar situations to those described here can arise whenever interfaces are used. Just keep in mind that if any concrete value has been stored in the interface, the interface will not be nil. For more information, see The Laws of Reflection at [https://golang.org/doc/articles/laws\_of\_reflection.html](https://golang.org/doc/articles/laws_of_reflection.html).

This text has been copied from [https://golang.org/doc/faq#nil\_error](https://golang.org/doc/faq#nil_error), licensed under the Creative Commons Attribution 3.0 License.

Available since

	2020.2


Default: off. Enable by setting `"analyses": {"SA4023": true}`.

Package documentation: [SA4023](https://staticcheck.dev/docs/checks/#SA4023)

<a id='SA4024'></a>
## `SA4024`: Checking for impossible return value from a builtin function

Return values of the len and cap builtins cannot be negative.

See [https://golang.org/pkg/builtin/#len](https://golang.org/pkg/builtin/#len) and [https://golang.org/pkg/builtin/#cap](https://golang.org/pkg/builtin/#cap).

Example:

	if len(slice) < 0 {
	    fmt.Println("unreachable code")
	}

Available since

	2021.1


Default: on.

Package documentation: [SA4024](https://staticcheck.dev/docs/checks/#SA4024)

<a id='SA4025'></a>
## `SA4025`: Integer division of literals that results in zero

When dividing two integer constants, the result will also be an integer. Thus, a division such as 2 / 3 results in 0. This is true for all of the following examples:

	_ = 2 / 3
	const _ = 2 / 3
	const _ float64 = 2 / 3
	_ = float64(2 / 3)

Staticcheck will flag such divisions if both sides of the division are integer literals, as it is highly unlikely that the division was intended to truncate to zero. Staticcheck will not flag integer division involving named constants, to avoid noisy positives.

Available since

	2021.1


Default: on.

Package documentation: [SA4025](https://staticcheck.dev/docs/checks/#SA4025)

<a id='SA4026'></a>
## `SA4026`: Go constants cannot express negative zero

In IEEE 754 floating point math, zero has a sign and can be positive or negative. This can be useful in certain numerical code.

Go constants, however, cannot express negative zero. This means that the literals -0.0 and 0.0 have the same ideal value (zero) and will both represent positive zero at runtime.

To explicitly and reliably create a negative zero, you can use the math.Copysign function: math.Copysign(0, -1).

Available since

	2021.1


Default: on.

Package documentation: [SA4026](https://staticcheck.dev/docs/checks/#SA4026)

<a id='SA4027'></a>
## `SA4027`: (*net/url.URL).Query returns a copy, modifying it doesn't change the URL

(\*net/url.URL).Query parses the current value of net/url.URL.RawQuery and returns it as a map of type net/url.Values. Subsequent changes to this map will not affect the URL unless the map gets encoded and assigned to the URL's RawQuery.

As a consequence, the following code pattern is an expensive no-op: u.Query().Add(key, value).

Available since

	2021.1


Default: on.

Package documentation: [SA4027](https://staticcheck.dev/docs/checks/#SA4027)

<a id='SA4028'></a>
## `SA4028`: x % 1 is always zero

Available since

	2022.1


Default: on.

Package documentation: [SA4028](https://staticcheck.dev/docs/checks/#SA4028)

<a id='SA4029'></a>
## `SA4029`: Ineffective attempt at sorting slice

sort.Float64Slice, sort.IntSlice, and sort.StringSlice are types, not functions. Doing x = sort.StringSlice(x) does nothing, especially not sort any values. The correct usage is sort.Sort(sort.StringSlice(x)) or sort.StringSlice(x).Sort(), but there are more convenient helpers, namely sort.Float64s, sort.Ints, and sort.Strings.

Available since

	2022.1


Default: on.

Package documentation: [SA4029](https://staticcheck.dev/docs/checks/#SA4029)

<a id='SA4030'></a>
## `SA4030`: Ineffective attempt at generating random number

Functions in the math/rand package that accept upper limits, such as Intn, generate random numbers in the half-open interval \[0,n). In other words, the generated numbers will be >= 0 and \< n – they don't include n. rand.Intn(1) therefore doesn't generate 0 or 1, it always generates 0.

Available since

	2022.1


Default: on.

Package documentation: [SA4030](https://staticcheck.dev/docs/checks/#SA4030)

<a id='SA4031'></a>
## `SA4031`: Checking never-nil value against nil

Available since

	2022.1


Default: off. Enable by setting `"analyses": {"SA4031": true}`.

Package documentation: [SA4031](https://staticcheck.dev/docs/checks/#SA4031)

<a id='SA4032'></a>
## `SA4032`: Comparing runtime.GOOS or runtime.GOARCH against impossible value

Available since

	2024.1


Default: on.

Package documentation: [SA4032](https://staticcheck.dev/docs/checks/#SA4032)

<a id='SA5000'></a>
## `SA5000`: Assignment to nil map

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA5000": true}`.

Package documentation: [SA5000](https://staticcheck.dev/docs/checks/#SA5000)

<a id='SA5001'></a>
## `SA5001`: Deferring Close before checking for a possible error

Available since

	2017.1


Default: on.

Package documentation: [SA5001](https://staticcheck.dev/docs/checks/#SA5001)

<a id='SA5002'></a>
## `SA5002`: The empty for loop ('for {}') spins and can block the scheduler

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA5002": true}`.

Package documentation: [SA5002](https://staticcheck.dev/docs/checks/#SA5002)

<a id='SA5003'></a>
## `SA5003`: Defers in infinite loops will never execute

Defers are scoped to the surrounding function, not the surrounding block. In a function that never returns, i.e. one containing an infinite loop, defers will never execute.

Available since

	2017.1


Default: on.

Package documentation: [SA5003](https://staticcheck.dev/docs/checks/#SA5003)

<a id='SA5004'></a>
## `SA5004`: 'for { select { ...' with an empty default branch spins

Available since

	2017.1


Default: on.

Package documentation: [SA5004](https://staticcheck.dev/docs/checks/#SA5004)

<a id='SA5005'></a>
## `SA5005`: The finalizer references the finalized object, preventing garbage collection

A finalizer is a function associated with an object that runs when the garbage collector is ready to collect said object, that is when the object is no longer referenced by anything.

If the finalizer references the object, however, it will always remain as the final reference to that object, preventing the garbage collector from collecting the object. The finalizer will never run, and the object will never be collected, leading to a memory leak. That is why the finalizer should instead use its first argument to operate on the object. That way, the number of references can temporarily go to zero before the object is being passed to the finalizer.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA5005": true}`.

Package documentation: [SA5005](https://staticcheck.dev/docs/checks/#SA5005)

<a id='SA5007'></a>
## `SA5007`: Infinite recursive call

A function that calls itself recursively needs to have an exit condition. Otherwise it will recurse forever, until the system runs out of memory.

This issue can be caused by simple bugs such as forgetting to add an exit condition. It can also happen "on purpose". Some languages have tail call optimization which makes certain infinite recursive calls safe to use. Go, however, does not implement TCO, and as such a loop should be used instead.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA5007": true}`.

Package documentation: [SA5007](https://staticcheck.dev/docs/checks/#SA5007)

<a id='SA5008'></a>
## `SA5008`: Invalid struct tag

Available since

	2019.2


Default: on.

Package documentation: [SA5008](https://staticcheck.dev/docs/checks/#SA5008)

<a id='SA5010'></a>
## `SA5010`: Impossible type assertion

Some type assertions can be statically proven to be impossible. This is the case when the method sets of both arguments of the type assertion conflict with each other, for example by containing the same method with different signatures.

The Go compiler already applies this check when asserting from an interface value to a concrete type. If the concrete type misses methods from the interface, or if function signatures don't match, then the type assertion can never succeed.

This check applies the same logic when asserting from one interface to another. If both interface types contain the same method but with different signatures, then the type assertion can never succeed, either.

Available since

	2020.1


Default: off. Enable by setting `"analyses": {"SA5010": true}`.

Package documentation: [SA5010](https://staticcheck.dev/docs/checks/#SA5010)

<a id='SA5011'></a>
## `SA5011`: Possible nil pointer dereference

A pointer is being dereferenced unconditionally, while also being checked against nil in another place. This suggests that the pointer may be nil and dereferencing it may panic. This is commonly a result of improperly ordered code or missing return statements. Consider the following examples:

	func fn(x *int) {
	    fmt.Println(*x)

	    // This nil check is equally important for the previous dereference
	    if x != nil {
	        foo(*x)
	    }
	}

	func TestFoo(t *testing.T) {
	    x := compute()
	    if x == nil {
	        t.Errorf("nil pointer received")
	    }

	    // t.Errorf does not abort the test, so if x is nil, the next line will panic.
	    foo(*x)
	}

Staticcheck tries to deduce which functions abort control flow. For example, it is aware that a function will not continue execution after a call to panic or log.Fatal. However, sometimes this detection fails, in particular in the presence of conditionals. Consider the following example:

	func Log(msg string, level int) {
	    fmt.Println(msg)
	    if level == levelFatal {
	        os.Exit(1)
	    }
	}

	func Fatal(msg string) {
	    Log(msg, levelFatal)
	}

	func fn(x *int) {
	    if x == nil {
	        Fatal("unexpected nil pointer")
	    }
	    fmt.Println(*x)
	}

Staticcheck will flag the dereference of x, even though it is perfectly safe. Staticcheck is not able to deduce that a call to Fatal will exit the program. For the time being, the easiest workaround is to modify the definition of Fatal like so:

	func Fatal(msg string) {
	    Log(msg, levelFatal)
	    panic("unreachable")
	}

We also hard-code functions from common logging packages such as logrus. Please file an issue if we're missing support for a popular package.

Available since

	2020.1


Default: off. Enable by setting `"analyses": {"SA5011": true}`.

Package documentation: [SA5011](https://staticcheck.dev/docs/checks/#SA5011)

<a id='SA5012'></a>
## `SA5012`: Passing odd-sized slice to function expecting even size

Some functions that take slices as parameters expect the slices to have an even number of elements.  Often, these functions treat elements in a slice as pairs.  For example, strings.NewReplacer takes pairs of old and new strings,  and calling it with an odd number of elements would be an error.

Available since

	2020.2


Default: off. Enable by setting `"analyses": {"SA5012": true}`.

Package documentation: [SA5012](https://staticcheck.dev/docs/checks/#SA5012)

<a id='SA6000'></a>
## `SA6000`: Using regexp.Match or related in a loop, should use regexp.Compile

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA6000": true}`.

Package documentation: [SA6000](https://staticcheck.dev/docs/checks/#SA6000)

<a id='SA6001'></a>
## `SA6001`: Missing an optimization opportunity when indexing maps by byte slices

Map keys must be comparable, which precludes the use of byte slices. This usually leads to using string keys and converting byte slices to strings.

Normally, a conversion of a byte slice to a string needs to copy the data and causes allocations. The compiler, however, recognizes m\[string(b)] and uses the data of b directly, without copying it, because it knows that the data can't change during the map lookup. This leads to the counter-intuitive situation that

	k := string(b)
	println(m[k])
	println(m[k])

will be less efficient than

	println(m[string(b)])
	println(m[string(b)])

because the first version needs to copy and allocate, while the second one does not.

For some history on this optimization, check out commit f5f5a8b6209f84961687d993b93ea0d397f5d5bf in the Go repository.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA6001": true}`.

Package documentation: [SA6001](https://staticcheck.dev/docs/checks/#SA6001)

<a id='SA6002'></a>
## `SA6002`: Storing non-pointer values in sync.Pool allocates memory

A sync.Pool is used to avoid unnecessary allocations and reduce the amount of work the garbage collector has to do.

When passing a value that is not a pointer to a function that accepts an interface, the value needs to be placed on the heap, which means an additional allocation. Slices are a common thing to put in sync.Pools, and they're structs with 3 fields (length, capacity, and a pointer to an array). In order to avoid the extra allocation, one should store a pointer to the slice instead.

See the comments on [https://go-review.googlesource.com/c/go/+/24371](https://go-review.googlesource.com/c/go/+/24371) that discuss this problem.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA6002": true}`.

Package documentation: [SA6002](https://staticcheck.dev/docs/checks/#SA6002)

<a id='SA6003'></a>
## `SA6003`: Converting a string to a slice of runes before ranging over it

You may want to loop over the runes in a string. Instead of converting the string to a slice of runes and looping over that, you can loop over the string itself. That is,

	for _, r := range s {}

and

	for _, r := range []rune(s) {}

will yield the same values. The first version, however, will be faster and avoid unnecessary memory allocations.

Do note that if you are interested in the indices, ranging over a string and over a slice of runes will yield different indices. The first one yields byte offsets, while the second one yields indices in the slice of runes.

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA6003": true}`.

Package documentation: [SA6003](https://staticcheck.dev/docs/checks/#SA6003)

<a id='SA6005'></a>
## `SA6005`: Inefficient string comparison with strings.ToLower or strings.ToUpper

Converting two strings to the same case and comparing them like so

	if strings.ToLower(s1) == strings.ToLower(s2) {
	    ...
	}

is significantly more expensive than comparing them with strings.EqualFold(s1, s2). This is due to memory usage as well as computational complexity.

strings.ToLower will have to allocate memory for the new strings, as well as convert both strings fully, even if they differ on the very first byte. strings.EqualFold, on the other hand, compares the strings one character at a time. It doesn't need to create two intermediate strings and can return as soon as the first non-matching character has been found.

For a more in-depth explanation of this issue, see [https://blog.digitalocean.com/how-to-efficiently-compare-strings-in-go/](https://blog.digitalocean.com/how-to-efficiently-compare-strings-in-go/)

Available since

	2019.2


Default: on.

Package documentation: [SA6005](https://staticcheck.dev/docs/checks/#SA6005)

<a id='SA6006'></a>
## `SA6006`: Using io.WriteString to write []byte

Using io.WriteString to write a slice of bytes, as in

	io.WriteString(w, string(b))

is both unnecessary and inefficient. Converting from \[]byte to string has to allocate and copy the data, and we could simply use w.Write(b) instead.

Available since

	2024.1


Default: on.

Package documentation: [SA6006](https://staticcheck.dev/docs/checks/#SA6006)

<a id='SA9001'></a>
## `SA9001`: Defers in range loops may not run when you expect them to

Available since

	2017.1


Default: off. Enable by setting `"analyses": {"SA9001": true}`.

Package documentation: [SA9001](https://staticcheck.dev/docs/checks/#SA9001)

<a id='SA9002'></a>
## `SA9002`: Using a non-octal os.FileMode that looks like it was meant to be in octal.

Available since

	2017.1


Default: on.

Package documentation: [SA9002](https://staticcheck.dev/docs/checks/#SA9002)

<a id='SA9003'></a>
## `SA9003`: Empty body in an if or else branch

Available since

	2017.1, non-default


Default: off. Enable by setting `"analyses": {"SA9003": true}`.

Package documentation: [SA9003](https://staticcheck.dev/docs/checks/#SA9003)

<a id='SA9004'></a>
## `SA9004`: Only the first constant has an explicit type

In a constant declaration such as the following:

	const (
	    First byte = 1
	    Second     = 2
	)

the constant Second does not have the same type as the constant First. This construct shouldn't be confused with

	const (
	    First byte = iota
	    Second
	)

where First and Second do indeed have the same type. The type is only passed on when no explicit value is assigned to the constant.

When declaring enumerations with explicit values it is therefore important not to write

	const (
	      EnumFirst EnumType = 1
	      EnumSecond         = 2
	      EnumThird          = 3
	)

This discrepancy in types can cause various confusing behaviors and bugs.

### Wrong type in variable declarations {#hdr-Wrong_type_in_variable_declarations}

The most obvious issue with such incorrect enumerations expresses itself as a compile error:

	package pkg

	const (
	    EnumFirst  uint8 = 1
	    EnumSecond       = 2
	)

	func fn(useFirst bool) {
	    x := EnumSecond
	    if useFirst {
	        x = EnumFirst
	    }
	}

fails to compile with

	./const.go:11:5: cannot use EnumFirst (type uint8) as type int in assignment

### Losing method sets {#hdr-Losing_method_sets}

A more subtle issue occurs with types that have methods and optional interfaces. Consider the following:

	package main

	import "fmt"

	type Enum int

	func (e Enum) String() string {
	    return "an enum"
	}

	const (
	    EnumFirst  Enum = 1
	    EnumSecond      = 2
	)

	func main() {
	    fmt.Println(EnumFirst)
	    fmt.Println(EnumSecond)
	}

This code will output

	an enum
	2

as EnumSecond has no explicit type, and thus defaults to int.

Available since

	2019.1


Default: on.

Package documentation: [SA9004](https://staticcheck.dev/docs/checks/#SA9004)

<a id='SA9005'></a>
## `SA9005`: Trying to marshal a struct with no public fields nor custom marshaling

The encoding/json and encoding/xml packages only operate on exported fields in structs, not unexported ones. It is usually an error to try to (un)marshal structs that only consist of unexported fields.

This check will not flag calls involving types that define custom marshaling behavior, e.g. via MarshalJSON methods. It will also not flag empty structs.

Available since

	2019.2


Default: off. Enable by setting `"analyses": {"SA9005": true}`.

Package documentation: [SA9005](https://staticcheck.dev/docs/checks/#SA9005)

<a id='SA9006'></a>
## `SA9006`: Dubious bit shifting of a fixed size integer value

Bit shifting a value past its size will always clear the value.

For instance:

	v := int8(42)
	v >>= 8

will always result in 0.

This check flags bit shifting operations on fixed size integer values only. That is, int, uint and uintptr are never flagged to avoid potential false positives in somewhat exotic but valid bit twiddling tricks:

	// Clear any value above 32 bits if integers are more than 32 bits.
	func f(i int) int {
	    v := i >> 32
	    v = v << 32
	    return i-v
	}

Available since

	2020.2


Default: on.

Package documentation: [SA9006](https://staticcheck.dev/docs/checks/#SA9006)

<a id='SA9007'></a>
## `SA9007`: Deleting a directory that shouldn't be deleted

It is virtually never correct to delete system directories such as /tmp or the user's home directory. However, it can be fairly easy to do by mistake, for example by mistakenly using os.TempDir instead of ioutil.TempDir, or by forgetting to add a suffix to the result of os.UserHomeDir.

Writing

	d := os.TempDir()
	defer os.RemoveAll(d)

in your unit tests will have a devastating effect on the stability of your system.

This check flags attempts at deleting the following directories:

\- os.TempDir - os.UserCacheDir - os.UserConfigDir - os.UserHomeDir

Available since

	2022.1


Default: off. Enable by setting `"analyses": {"SA9007": true}`.

Package documentation: [SA9007](https://staticcheck.dev/docs/checks/#SA9007)

<a id='SA9008'></a>
## `SA9008`: else branch of a type assertion is probably not reading the right value

When declaring variables as part of an if statement (like in 'if foo := ...; foo {'), the same variables will also be in the scope of the else branch. This means that in the following example

	if x, ok := x.(int); ok {
	    // ...
	} else {
	    fmt.Printf("unexpected type %T", x)
	}

x in the else branch will refer to the x from x, ok :=; it will not refer to the x that is being type-asserted. The result of a failed type assertion is the zero value of the type that is being asserted to, so x in the else branch will always have the value 0 and the type int.

Available since

	2022.1


Default: off. Enable by setting `"analyses": {"SA9008": true}`.

Package documentation: [SA9008](https://staticcheck.dev/docs/checks/#SA9008)

<a id='SA9009'></a>
## `SA9009`: Ineffectual Go compiler directive

A potential Go compiler directive was found, but is ineffectual as it begins with whitespace.

Available since

	2024.1


Default: on.

Package documentation: [SA9009](https://staticcheck.dev/docs/checks/#SA9009)

<a id='ST1000'></a>
## `ST1000`: Incorrect or missing package comment

Packages must have a package comment that is formatted according to the guidelines laid out in [https://go.dev/wiki/CodeReviewComments#package-comments](https://go.dev/wiki/CodeReviewComments#package-comments).

Available since

	2019.1, non-default


Default: off. Enable by setting `"analyses": {"ST1000": true}`.

Package documentation: [ST1000](https://staticcheck.dev/docs/checks/#ST1000)

<a id='ST1001'></a>
## `ST1001`: Dot imports are discouraged

Dot imports that aren't in external test packages are discouraged.

The dot\_import\_whitelist option can be used to whitelist certain imports.

Quoting Go Code Review Comments:

> The import . form can be useful in tests that, due to circular > dependencies, cannot be made part of the package being tested: >  >     package foo\_test >  >     import ( >         "bar/testutil" // also imports "foo" >         . "foo" >     ) >  > In this case, the test file cannot be in package foo because it > uses bar/testutil, which imports foo. So we use the import . > form to let the file pretend to be part of package foo even though > it is not. Except for this one case, do not use import . in your > programs. It makes the programs much harder to read because it is > unclear whether a name like Quux is a top-level identifier in the > current package or in an imported package.

Available since

	2019.1

Options

	dot_import_whitelist


Default: off. Enable by setting `"analyses": {"ST1001": true}`.

Package documentation: [ST1001](https://staticcheck.dev/docs/checks/#ST1001)

<a id='ST1003'></a>
## `ST1003`: Poorly chosen identifier

Identifiers, such as variable and package names, follow certain rules.

See the following links for details:

\- [https://go.dev/doc/effective\_go#package-names](https://go.dev/doc/effective_go#package-names) - [https://go.dev/doc/effective\_go#mixed-caps](https://go.dev/doc/effective_go#mixed-caps) - [https://go.dev/wiki/CodeReviewComments#initialisms](https://go.dev/wiki/CodeReviewComments#initialisms) - [https://go.dev/wiki/CodeReviewComments#variable-names](https://go.dev/wiki/CodeReviewComments#variable-names)

Available since

	2019.1, non-default

Options

	initialisms


Default: off. Enable by setting `"analyses": {"ST1003": true}`.

Package documentation: [ST1003](https://staticcheck.dev/docs/checks/#ST1003)

<a id='ST1005'></a>
## `ST1005`: Incorrectly formatted error string

Error strings follow a set of guidelines to ensure uniformity and good composability.

Quoting Go Code Review Comments:

> Error strings should not be capitalized (unless beginning with > proper nouns or acronyms) or end with punctuation, since they are > usually printed following other context. That is, use > fmt.Errorf("something bad") not fmt.Errorf("Something bad"), so > that log.Printf("Reading %s: %v", filename, err) formats without a > spurious capital letter mid-message.

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1005": true}`.

Package documentation: [ST1005](https://staticcheck.dev/docs/checks/#ST1005)

<a id='ST1006'></a>
## `ST1006`: Poorly chosen receiver name

Quoting Go Code Review Comments:

> The name of a method's receiver should be a reflection of its > identity; often a one or two letter abbreviation of its type > suffices (such as "c" or "cl" for "Client"). Don't use generic > names such as "me", "this" or "self", identifiers typical of > object-oriented languages that place more emphasis on methods as > opposed to functions. The name need not be as descriptive as that > of a method argument, as its role is obvious and serves no > documentary purpose. It can be very short as it will appear on > almost every line of every method of the type; familiarity admits > brevity. Be consistent, too: if you call the receiver "c" in one > method, don't call it "cl" in another.

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1006": true}`.

Package documentation: [ST1006](https://staticcheck.dev/docs/checks/#ST1006)

<a id='ST1008'></a>
## `ST1008`: A function's error value should be its last return value

A function's error value should be its last return value.

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1008": true}`.

Package documentation: [ST1008](https://staticcheck.dev/docs/checks/#ST1008)

<a id='ST1011'></a>
## `ST1011`: Poorly chosen name for variable of type time.Duration

time.Duration values represent an amount of time, which is represented as a count of nanoseconds. An expression like 5 \* time.Microsecond yields the value 5000. It is therefore not appropriate to suffix a variable of type time.Duration with any time unit, such as Msec or Milli.

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1011": true}`.

Package documentation: [ST1011](https://staticcheck.dev/docs/checks/#ST1011)

<a id='ST1012'></a>
## `ST1012`: Poorly chosen name for error variable

Error variables that are part of an API should be called errFoo or ErrFoo.

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1012": true}`.

Package documentation: [ST1012](https://staticcheck.dev/docs/checks/#ST1012)

<a id='ST1013'></a>
## `ST1013`: Should use constants for HTTP error codes, not magic numbers

HTTP has a tremendous number of status codes. While some of those are well known (200, 400, 404, 500), most of them are not. The net/http package provides constants for all status codes that are part of the various specifications. It is recommended to use these constants instead of hard-coding magic numbers, to vastly improve the readability of your code.

Available since

	2019.1

Options

	http_status_code_whitelist


Default: off. Enable by setting `"analyses": {"ST1013": true}`.

Package documentation: [ST1013](https://staticcheck.dev/docs/checks/#ST1013)

<a id='ST1015'></a>
## `ST1015`: A switch's default case should be the first or last case

Available since

	2019.1


Default: off. Enable by setting `"analyses": {"ST1015": true}`.

Package documentation: [ST1015](https://staticcheck.dev/docs/checks/#ST1015)

<a id='ST1016'></a>
## `ST1016`: Use consistent method receiver names

Available since

	2019.1, non-default


Default: off. Enable by setting `"analyses": {"ST1016": true}`.

Package documentation: [ST1016](https://staticcheck.dev/docs/checks/#ST1016)

<a id='ST1017'></a>
## `ST1017`: Don't use Yoda conditions

Yoda conditions are conditions of the kind 'if 42 == x', where the literal is on the left side of the comparison. These are a common idiom in languages in which assignment is an expression, to avoid bugs of the kind 'if (x = 42)'. In Go, which doesn't allow for this kind of bug, we prefer the more idiomatic 'if x == 42'.

Available since

	2019.2


Default: off. Enable by setting `"analyses": {"ST1017": true}`.

Package documentation: [ST1017](https://staticcheck.dev/docs/checks/#ST1017)

<a id='ST1018'></a>
## `ST1018`: Avoid zero-width and control characters in string literals

Available since

	2019.2


Default: off. Enable by setting `"analyses": {"ST1018": true}`.

Package documentation: [ST1018](https://staticcheck.dev/docs/checks/#ST1018)

<a id='ST1019'></a>
## `ST1019`: Importing the same package multiple times

Go allows importing the same package multiple times, as long as different import aliases are being used. That is, the following bit of code is valid:

	import (
	    "fmt"
	    fumpt "fmt"
	    format "fmt"
	)

However, this is very rarely done on purpose. Usually, it is a sign of code that got refactored, accidentally adding duplicate import statements. It is also a rarely known feature, which may contribute to confusion.

Do note that sometimes, this feature may be used intentionally (see for example [https://github.com/golang/go/commit/3409ce39bfd7584523b7a8c150a310cea92d879d](https://github.com/golang/go/commit/3409ce39bfd7584523b7a8c150a310cea92d879d)) – if you want to allow this pattern in your code base, you're advised to disable this check.

It is acceptable to import the same package twice if one of the imports uses the blank identifier. This is allowed in order to increase resilience against erroneous changes when using the same package for its side effects as well as its exported API.

Available since

	2020.1


Default: off. Enable by setting `"analyses": {"ST1019": true}`.

Package documentation: [ST1019](https://staticcheck.dev/docs/checks/#ST1019)

<a id='ST1020'></a>
## `ST1020`: The documentation of an exported function should start with the function's name

Doc comments work best as complete sentences, which allow a wide variety of automated presentations. The first sentence should be a one-sentence summary that starts with the name being declared.

If every doc comment begins with the name of the item it describes, you can use the doc subcommand of the go tool and run the output through grep.

See [https://go.dev/doc/effective\_go#commentary](https://go.dev/doc/effective_go#commentary) for more information on how to write good documentation.

Available since

	2020.1, non-default


Default: off. Enable by setting `"analyses": {"ST1020": true}`.

Package documentation: [ST1020](https://staticcheck.dev/docs/checks/#ST1020)

<a id='ST1021'></a>
## `ST1021`: The documentation of an exported type should start with type's name

Doc comments work best as complete sentences, which allow a wide variety of automated presentations. The first sentence should be a one-sentence summary that starts with the name being declared.

If every doc comment begins with the name of the item it describes, you can use the doc subcommand of the go tool and run the output through grep.

See [https://go.dev/doc/effective\_go#commentary](https://go.dev/doc/effective_go#commentary) for more information on how to write good documentation.

Available since

	2020.1, non-default


Default: off. Enable by setting `"analyses": {"ST1021": true}`.

Package documentation: [ST1021](https://staticcheck.dev/docs/checks/#ST1021)

<a id='ST1022'></a>
## `ST1022`: The documentation of an exported variable or constant should start with variable's name

Doc comments work best as complete sentences, which allow a wide variety of automated presentations. The first sentence should be a one-sentence summary that starts with the name being declared.

If every doc comment begins with the name of the item it describes, you can use the doc subcommand of the go tool and run the output through grep.

See [https://go.dev/doc/effective\_go#commentary](https://go.dev/doc/effective_go#commentary) for more information on how to write good documentation.

Available since

	2020.1, non-default


Default: off. Enable by setting `"analyses": {"ST1022": true}`.

Package documentation: [ST1022](https://staticcheck.dev/docs/checks/#ST1022)

<a id='ST1023'></a>
## `ST1023`: Redundant type in variable declaration

Available since

	2021.1, non-default


Default: off. Enable by setting `"analyses": {"ST1023": true}`.

Package documentation: [ST1023](https://staticcheck.dev/docs/checks/#)

<a id='any'></a>
## `any`: replace interface{} with any

The any analyzer suggests replacing uses of the empty interface type, \`interface{}\`, with the \`any\` alias, which was introduced in Go 1.18. This is a purely stylistic change that makes code more readable.


Default: on.

Package documentation: [any](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#any)

<a id='appendclipped'></a>
## `appendclipped`: simplify append chains using slices.Concat

The appendclipped analyzer suggests replacing chains of append calls with a single call to slices.Concat, which was added in Go 1.21. For example, append(append(s, s1...), s2...) would be simplified to slices.Concat(s, s1, s2).

In the simple case of appending to a newly allocated slice, such as append(\[]T(nil), s...), the analyzer suggests the more concise slices.Clone(s). For byte slices, it will prefer bytes.Clone if the "bytes" package is already imported.

This fix is only applied when the base of the append tower is a "clipped" slice, meaning its length and capacity are equal (e.g. x\[:0:0] or \[]T{}). This is to avoid changing program behavior by eliminating intended side effects on the base slice's underlying array.

This analyzer is currently disabled by default as the transformation does not preserve the nilness of the base slice in all cases; see [https://go.dev/issue/73557](https://go.dev/issue/73557).


Default: off. Enable by setting `"analyses": {"appendclipped": true}`.

Package documentation: [appendclipped](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#appendclipped)

<a id='appends'></a>
## `appends`: check for missing values after append

This checker reports calls to append that pass no values to be appended to the slice.

	s := []string{"a", "b", "c"}
	_ = append(s)

Such calls are always no-ops and often indicate an underlying mistake.


Default: on.

Package documentation: [appends](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/appends)

<a id='asmdecl'></a>
## `asmdecl`: report mismatches between assembly files and Go declarations



Default: on.

Package documentation: [asmdecl](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/asmdecl)

<a id='assign'></a>
## `assign`: check for useless assignments

This checker reports assignments of the form x = x or a\[i] = a\[i]. These are almost always useless, and even when they aren't they are usually a mistake.


Default: on.

Package documentation: [assign](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/assign)

<a id='atomic'></a>
## `atomic`: check for common mistakes using the sync/atomic package

The atomic checker looks for assignment statements of the form:

	x = atomic.AddUint64(&x, 1)

which are not atomic.


Default: on.

Package documentation: [atomic](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomic)

<a id='atomicalign'></a>
## `atomicalign`: check for non-64-bits-aligned arguments to sync/atomic functions



Default: on.

Package documentation: [atomicalign](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomicalign)

<a id='atomictypes'></a>
## `atomictypes`: replace basic types in sync/atomic calls with atomic types

The atomictypes analyzer suggests replacing the primitive sync/atomic functions with the strongly typed atomic wrapper types introduced in Go1.19 (e.g. atomic.Int32). For example,

	var x int32
	atomic.AddInt32(&x, 1)

would become

	var x atomic.Int32
	x.Add(1)

The atomic types are safer because they don't allow non-atomic access, which is a common source of bugs. These types also resolve memory alignment issues that plagued the old atomic functions on 32-bit architectures.


Default: on.

Package documentation: [atomictypes](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#atomictypes)

<a id='bloop'></a>
## `bloop`: replace for-range over b.N with b.Loop

The bloop analyzer suggests replacing benchmark loops of the form \`for i := 0; i \< b.N; i++\` or \`for range b.N\` with the more modern \`for b.Loop()\`, which was added in Go 1.24.

This change makes benchmark code more readable and also removes the need for manual timer control, so any preceding calls to b.StartTimer, b.StopTimer, or b.ResetTimer within the same function will also be removed.

Caveats: The b.Loop() method is designed to prevent the compiler from optimizing away the benchmark loop, which can occasionally result in slower execution due to increased allocations in some specific cases. Since its fix may change the performance of nanosecond-scale benchmarks, bloop is disabled by default in the \`go fix\` analyzer suite; see golang/go#74967.


Default: on.

Package documentation: [bloop](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#bloop)

<a id='bools'></a>
## `bools`: check for common mistakes involving boolean operators



Default: on.

Package documentation: [bools](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/bools)

<a id='buildtag'></a>
## `buildtag`: check //go:build and // +build directives



Default: on.

Package documentation: [buildtag](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/buildtag)

<a id='cgocall'></a>
## `cgocall`: detect some violations of the cgo pointer passing rules

Check for invalid cgo pointer passing. This looks for code that uses cgo to call C code passing values whose types are almost always invalid according to the cgo pointer sharing rules. Specifically, it warns about attempts to pass a Go chan, map, func, or slice to C, either directly, or via a pointer, array, or struct.


Default: on.

Package documentation: [cgocall](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/cgocall)

<a id='composites'></a>
## `composites`: check for unkeyed composite literals

This analyzer reports a diagnostic for composite literals of struct types imported from another package that do not use the field-keyed syntax. Such literals are fragile because the addition of a new field (even if unexported) to the struct will cause compilation to fail.

As an example,

	err = &net.DNSConfigError{err}

should be replaced by:

	err = &net.DNSConfigError{Err: err}


Default: on.

Package documentation: [composites](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/composite)

<a id='copylocks'></a>
## `copylocks`: check for locks erroneously passed by value

Inadvertently copying a value containing a lock, such as sync.Mutex or sync.WaitGroup, may cause both copies to malfunction. Generally such values should be referred to through a pointer.


Default: on.

Package documentation: [copylocks](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/copylock)

<a id='deepequalerrors'></a>
## `deepequalerrors`: check for calls of reflect.DeepEqual on error values

The deepequalerrors checker looks for calls of the form:

	reflect.DeepEqual(err1, err2)

where err1 and err2 are errors. Using reflect.DeepEqual to compare errors is discouraged.


Default: on.

Package documentation: [deepequalerrors](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/deepequalerrors)

<a id='defers'></a>
## `defers`: report common mistakes in defer statements

The defers analyzer reports a diagnostic when a defer statement would result in a non-deferred call to time.Since, as experience has shown that this is nearly always a mistake.

For example:

	start := time.Now()
	...
	defer recordLatency(time.Since(start)) // error: call to time.Since is not deferred

The correct code is:

	defer func() { recordLatency(time.Since(start)) }()


Default: on.

Package documentation: [defers](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/defers)

<a id='deprecated'></a>
## `deprecated`: check for use of deprecated identifiers

The deprecated analyzer looks for deprecated symbols and package imports.

See [https://go.dev/wiki/Deprecated](https://go.dev/wiki/Deprecated) to learn about Go's convention for documenting and signaling deprecated identifiers.


Default: on.

Package documentation: [deprecated](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/deprecated)

<a id='directive'></a>
## `directive`: check Go toolchain directives such as //go:debug

This analyzer checks for problems with known Go toolchain directives in all Go source files in a package directory, even those excluded by //go:build constraints, and all non-Go source files too.

For //go:debug (see [https://go.dev/doc/godebug](https://go.dev/doc/godebug)), the analyzer checks that the directives are placed only in Go source files, only above the package comment, and only in package main or \*\_test.go files.

Support for other known directives may be added in the future.

This analyzer does not check //go:build, which is handled by the buildtag analyzer.


Default: on.

Package documentation: [directive](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/directive)

<a id='embed'></a>
## `embed`: check //go:embed directive usage

This analyzer checks that the embed package is imported if //go:embed directives are present, providing a suggested fix to add the import if it is missing.

This analyzer also checks that //go:embed directives precede the declaration of a single variable.


Default: on.

Package documentation: [embed](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/embeddirective)

<a id='errorsas'></a>
## `errorsas`: report passing non-pointer or non-error values to errors.As

The errorsas analyzer reports calls to errors.As where the type of the second argument is not a pointer to a type implementing error.


Default: on.

Package documentation: [errorsas](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/errorsas)

<a id='errorsastype'></a>
## `errorsastype`: replace errors.As with errors.AsType[T]

This analyzer suggests fixes to simplify uses of [errors.As](/errors#As) of this form:

	var myerr *MyErr
	if errors.As(err, &myerr) {
		handle(myerr)
	}

by using the less error-prone generic [errors.AsType](/errors#AsType) function, introduced in Go 1.26:

	if myerr, ok := errors.AsType[*MyErr](err); ok {
		handle(myerr)
	}

The fix is only offered if the var declaration has the form shown and there are no uses of myerr outside the if statement.


Default: on.

Package documentation: [errorsastype](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#errorsastype)

<a id='fieldalignment'></a>
## `fieldalignment`: find structs that would use less memory if their fields were sorted

This analyzer finds structs that can be rearranged to use less memory, and provides a suggested edit with the most compact order.

Note that there are two different diagnostics reported. One checks struct size, and the other reports "pointer bytes" used. Pointer bytes is how many bytes of the object that the garbage collector has to potentially scan for pointers, for example:

	struct { uint32; string }

have 16 pointer bytes because the garbage collector has to scan up through the string's inner pointer.

	struct { string; *uint32 }

has 24 pointer bytes because it has to scan further through the \*uint32.

	struct { string; uint32 }

has 8 because it can stop immediately after the string pointer.

Be aware that the most compact order is not always the most efficient. In rare cases it may cause two variables each updated by its own goroutine to occupy the same CPU cache line, inducing a form of memory contention known as "false sharing" that slows down both goroutines.

Unlike most analyzers, which report likely mistakes, the diagnostics produced by fieldanalyzer very rarely indicate a significant problem, so the analyzer is not included in typical suites such as vet or gopls. Use this standalone command to run it on your code:

	$ go install golang.org/x/tools/go/analysis/passes/fieldalignment/cmd/fieldalignment@latest
	$ fieldalignment [packages]


Default: off. Enable by setting `"analyses": {"fieldalignment": true}`.

Package documentation: [fieldalignment](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/fieldalignment)

<a id='fillreturns'></a>
## `fillreturns`: suggest fixes for errors due to an incorrect number of return values

This checker provides suggested fixes for type errors of the type "wrong number of return values (want %d, got %d)". For example:

	func m() (int, string, *bool, error) {
		return
	}

will turn into

	func m() (int, string, *bool, error) {
		return 0, "", nil, nil
	}

This functionality is similar to [https://github.com/sqs/goreturns](https://github.com/sqs/goreturns).


Default: on.

Package documentation: [fillreturns](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillreturns)

<a id='fmtappendf'></a>
## `fmtappendf`: replace []byte(fmt.Sprintf) with fmt.Appendf

The fmtappendf analyzer suggests replacing \`\[]byte(fmt.Sprintf(...))\` with \`fmt.Appendf(nil, ...)\`. This avoids the intermediate allocation of a string by Sprintf, making the code more efficient. The suggestion also applies to fmt.Sprint and fmt.Sprintln.


Default: on.

Package documentation: [fmtappendf](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#fmtappendf)

<a id='forvar'></a>
## `forvar`: remove redundant re-declaration of loop variables

The forvar analyzer removes unnecessary shadowing of loop variables. Before Go 1.22, it was common to write \`for \_, x := range s { x := x ... }\` to create a fresh variable for each iteration. Go 1.22 changed the semantics of \`for\` loops, making this pattern redundant. This analyzer removes the unnecessary \`x := x\` statement.

This fix only applies to \`range\` loops.


Default: on.

Package documentation: [forvar](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#forvar)

<a id='framepointer'></a>
## `framepointer`: report assembly that clobbers the frame pointer before saving it



Default: on.

Package documentation: [framepointer](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/framepointer)

<a id='hostport'></a>
## `hostport`: check format of addresses passed to net.Dial

This analyzer flags code that produce network address strings using fmt.Sprintf, as in this example:

	addr := fmt.Sprintf("%s:%d", host, 12345) // "will not work with IPv6"
	...
	conn, err := net.Dial("tcp", addr)       // "when passed to dial here"

The analyzer suggests a fix to use the correct approach, a call to net.JoinHostPort:

	addr := net.JoinHostPort(host, "12345")
	...
	conn, err := net.Dial("tcp", addr)

A similar diagnostic and fix are produced for a format string of "%s:%s".


Default: on.

Package documentation: [hostport](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/hostport)

<a id='httpresponse'></a>
## `httpresponse`: check for mistakes using HTTP responses

A common mistake when using the net/http package is to defer a function call to close the http.Response Body before checking the error that determines whether the response is valid:

	resp, err := http.Head(url)
	defer resp.Body.Close()
	if err != nil {
		log.Fatal(err)
	}
	// (defer statement belongs here)

This checker helps uncover latent nil dereference bugs by reporting a diagnostic for such mistakes.


Default: on.

Package documentation: [httpresponse](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/httpresponse)

<a id='ifaceassert'></a>
## `ifaceassert`: detect impossible interface-to-interface type assertions

This checker flags type assertions v.(T) and corresponding type-switch cases in which the static type V of v is an interface that cannot possibly implement the target interface T. This occurs when V and T contain methods with the same name but different signatures. Example:

	var v interface {
		Read()
	}
	_ = v.(io.Reader)

The Read method in v has a different signature than the Read method in io.Reader, so this assertion cannot succeed.


Default: on.

Package documentation: [ifaceassert](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/ifaceassert)

<a id='infertypeargs'></a>
## `infertypeargs`: check for unnecessary type arguments in call expressions

Explicit type arguments may be omitted from call expressions if they can be inferred from function arguments, or from other type arguments:

	func f[T any](T) {}

	func _() {
		f[string]("foo") // string could be inferred
	}


Default: on.

Package documentation: [infertypeargs](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/infertypeargs)

<a id='inline'></a>
## `inline`: apply fixes based on 'go:fix inline' comment directives

The inline analyzer inlines functions and constants that are marked for inlining.

\## Functions

Given a function that is marked for inlining, like this one:

	//go:fix inline
	func Square(x int) int { return Pow(x, 2) }

this analyzer will recommend that calls to the function elsewhere, in the same or other packages, should be inlined.

Inlining can be used to move off of a deprecated function:

	// Deprecated: prefer Pow(x, 2).
	//go:fix inline
	func Square(x int) int { return Pow(x, 2) }

It can also be used to move off of an obsolete package, as when the import path has changed or a higher major version is available:

	package pkg

	import pkg2 "pkg/v2"

	//go:fix inline
	func F() { pkg2.F(nil) }

Replacing a call pkg.F() by pkg2.F(nil) can have no effect on the program, so this mechanism provides a low-risk way to update large numbers of calls. We recommend, where possible, expressing the old API in terms of the new one to enable automatic migration.

The inliner takes care to avoid behavior changes, even subtle ones, such as changes to the order in which argument expressions are evaluated. When it cannot safely eliminate all parameter variables, it may introduce a "binding declaration" of the form

	var params = args

to evaluate argument expressions in the correct order and bind them to parameter variables. Since the resulting code transformation may be stylistically suboptimal, such inlinings may be disabled by specifying the -inline.allow\_binding\_decl=false flag to the analyzer driver.

(In cases where it is not safe to "reduce" a call—that is, to replace a call f(x) by the body of function f, suitably substituted—the inliner machinery is capable of replacing f by a function literal, func(){...}(). However, the inline analyzer discards all such "literalizations" unconditionally, again on grounds of style.)

\## Constants

Given a constant that is marked for inlining, like this one:

	//go:fix inline
	const Ptr = Pointer

this analyzer will recommend that uses of Ptr should be replaced with Pointer.

As with functions, inlining can be used to replace deprecated constants and constants in obsolete packages.

A constant definition can be marked for inlining only if it refers to another named constant.

The "//go:fix inline" comment must appear before a single const declaration on its own, as above; before a const declaration that is part of a group, as in this case:

	const (
	   C = 1
	   //go:fix inline
	   Ptr = Pointer
	)

or before a group, applying to every constant in the group:

	//go:fix inline
	const (
		Ptr = Pointer
	    Val = Value
	)

The proposal [https://go.dev/issue/32816](https://go.dev/issue/32816) introduces the "//go:fix inline" directives.

You can use this command to apply inline fixes en masse:

	$ go run golang.org/x/tools/go/analysis/passes/inline/cmd/inline@latest -fix ./...


Default: on.

Package documentation: [inline](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/inline)

<a id='loopclosure'></a>
## `loopclosure`: check references to loop variables from within nested functions

This analyzer reports places where a function literal references the iteration variable of an enclosing loop, and the loop calls the function in such a way (e.g. with go or defer) that it may outlive the loop iteration and possibly observe the wrong value of the variable.

Note: An iteration variable can only outlive a loop iteration in Go versions \<=1.21. In Go 1.22 and later, the loop variable lifetimes changed to create a new iteration variable per loop iteration. (See go.dev/issue/60078.)

In this example, all the deferred functions run after the loop has completed, so all observe the final value of v \[\<go1.22].

	for _, v := range list {
	    defer func() {
	        use(v) // incorrect
	    }()
	}

One fix is to create a new variable for each iteration of the loop:

	for _, v := range list {
	    v := v // new var per iteration
	    defer func() {
	        use(v) // ok
	    }()
	}

After Go version 1.22, the previous two for loops are equivalent and both are correct.

The next example uses a go statement and has a similar problem \[\<go1.22]. In addition, it has a data race because the loop updates v concurrent with the goroutines accessing it.

	for _, v := range elem {
	    go func() {
	        use(v)  // incorrect, and a data race
	    }()
	}

A fix is the same as before. The checker also reports problems in goroutines started by golang.org/x/sync/errgroup.Group. A hard-to-spot variant of this form is common in parallel tests:

	func Test(t *testing.T) {
	    for _, test := range tests {
	        t.Run(test.name, func(t *testing.T) {
	            t.Parallel()
	            use(test) // incorrect, and a data race
	        })
	    }
	}

The t.Parallel() call causes the rest of the function to execute concurrent with the loop \[\<go1.22].

The analyzer reports references only in the last statement, as it is not deep enough to understand the effects of subsequent statements that might render the reference benign. ("Last statement" is defined recursively in compound statements such as if, switch, and select.)

See: [https://golang.org/doc/go\_faq.html#closures\_and\_goroutines](https://golang.org/doc/go_faq.html#closures_and_goroutines)


Default: on.

Package documentation: [loopclosure](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/loopclosure)

<a id='lostcancel'></a>
## `lostcancel`: check cancel func returned by context.WithCancel is called

The cancellation function returned by context.WithCancel, WithTimeout, WithDeadline and variants such as WithCancelCause must be called, or the new context will remain live until its parent context is cancelled. (The background context is never cancelled.)


Default: on.

Package documentation: [lostcancel](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/lostcancel)

<a id='maprange'></a>
## `maprange`: checks for unnecessary calls to maps.Keys and maps.Values in range statements

Consider a loop written like this:

	for val := range maps.Values(m) {
		fmt.Println(val)
	}

This should instead be written without the call to maps.Values:

	for _, val := range m {
		fmt.Println(val)
	}

golang.org/x/exp/maps returns slices for Keys/Values instead of iterators, but unnecessary calls should similarly be removed:

	for _, key := range maps.Keys(m) {
		fmt.Println(key)
	}

should be rewritten as:

	for key := range m {
		fmt.Println(key)
	}


Default: on.

Package documentation: [maprange](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/maprange)

<a id='mapsloop'></a>
## `mapsloop`: replace explicit loops over maps with calls to maps package

The mapsloop analyzer replaces loops of the form

	for k, v := range x { m[k] = v }

with a single call to a function from the \`maps\` package, added in Go 1.23. Depending on the context, this could be \`maps.Copy\`, \`maps.Insert\`, \`maps.Clone\`, or \`maps.Collect\`.

The transformation to \`maps.Clone\` is applied conservatively, as it preserves the nilness of the source map, which may be a subtle change in behavior if the original code did not handle a nil map in the same way.


Default: on.

Package documentation: [mapsloop](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#mapsloop)

<a id='minmax'></a>
## `minmax`: replace if/else statements with calls to min or max

The minmax analyzer simplifies conditional assignments by suggesting the use of the built-in \`min\` and \`max\` functions, introduced in Go 1.21. For example,

	if a < b { x = a } else { x = b }

is replaced by

	x = min(a, b).

This analyzer avoids making suggestions for floating-point types, as the behavior of \`min\` and \`max\` with NaN values can differ from the original if/else statement.


Default: on.

Package documentation: [minmax](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#minmax)

<a id='newexpr'></a>
## `newexpr`: simplify code by using go1.26's new(expr)

This analyzer finds declarations of functions of this form:

	func varOf(x int) *int { return &x }

and suggests a fix to turn them into inlinable wrappers around go1.26's built-in new(expr) function:

	//go:fix inline
	func varOf(x int) *int { return new(x) }

(The directive comment causes the 'inline' analyzer to suggest that calls to such functions are inlined.)

In addition, this analyzer suggests a fix for each call to one of the functions before it is transformed, so that

	use(varOf(123))

is replaced by:

	use(new(123))

Wrapper functions such as varOf are common when working with Go serialization packages such as for JSON or protobuf, where pointers are often used to express optionality.


Default: on.

Package documentation: [newexpr](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#newexpr)

<a id='nilfunc'></a>
## `nilfunc`: check for useless comparisons between functions and nil

A useless comparison is one like f == nil as opposed to f() == nil.


Default: on.

Package documentation: [nilfunc](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilfunc)

<a id='nilness'></a>
## `nilness`: check for redundant or impossible nil comparisons

The nilness checker inspects the control-flow graph of each function in a package and reports nil pointer dereferences, degenerate nil pointers, and panics with nil values. A degenerate comparison is of the form x==nil or x!=nil where x is statically known to be nil or non-nil. These are often a mistake, especially in control flow related to errors. Panics with nil values are checked because they are not detectable by

	if r := recover(); r != nil {

This check reports conditions such as:

	if f == nil { // impossible condition (f is a function)
	}

and:

	p := &v
	...
	if p != nil { // tautological condition
	}

and:

	if p == nil {
		print(*p) // nil dereference
	}

and:

	if p == nil {
		panic(p)
	}

Sometimes the control flow may be quite complex, making bugs hard to spot. In the example below, the err.Error expression is guaranteed to panic because, after the first return, err must be nil. The intervening loop is just a distraction.

	...
	err := g.Wait()
	if err != nil {
		return err
	}
	partialSuccess := false
	for _, err := range errs {
		if err == nil {
			partialSuccess = true
			break
		}
	}
	if partialSuccess {
		reportStatus(StatusMessage{
			Code:   code.ERROR,
			Detail: err.Error(), // "nil dereference in dynamic method call"
		})
		return nil
	}

...


Default: on.

Package documentation: [nilness](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilness)

<a id='nonewvars'></a>
## `nonewvars`: suggested fixes for "no new vars on left side of :="

This checker provides suggested fixes for type errors of the type "no new vars on left side of :=". For example:

	z := 1
	z := 2

will turn into

	z := 1
	z = 2


Default: on.

Package documentation: [nonewvars](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/nonewvars)

<a id='noresultvalues'></a>
## `noresultvalues`: suggested fixes for unexpected return values

This checker provides suggested fixes for type errors of the type "no result values expected" or "too many return values". For example:

	func z() { return nil }

will turn into

	func z() { return }


Default: on.

Package documentation: [noresultvalues](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/noresultvalues)

<a id='omitzero'></a>
## `omitzero`: suggest replacing omitempty with omitzero for struct fields

The omitzero analyzer identifies uses of the \`omitempty\` JSON struct tag on fields that are themselves structs. For struct-typed fields, the \`omitempty\` tag has no effect on the behavior of json.Marshal and json.Unmarshal. The analyzer offers two suggestions: either remove the tag, or replace it with \`omitzero\` (added in Go 1.24), which correctly omits the field if the struct value is zero.

However, some other serialization packages (notably kubebuilder, see [https://book.kubebuilder.io/reference/markers.html](https://book.kubebuilder.io/reference/markers.html)) may have their own interpretation of the \`json:",omitzero"\` tag, so removing it may affect program behavior. For this reason, the omitzero modernizer will not make changes in any package that contains +kubebuilder annotations.

Replacing \`omitempty\` with \`omitzero\` is a change in behavior. The original code would always encode the struct field, whereas the modified code will omit it if it is a zero-value.


Default: on.

Package documentation: [omitzero](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#omitzero)

<a id='plusbuild'></a>
## `plusbuild`: remove obsolete //+build comments

The plusbuild analyzer suggests a fix to remove obsolete build tags of the form:

	//+build linux,amd64

in files that also contain a Go 1.18-style tag such as:

	//go:build linux && amd64

(It does not check that the old and new tags are consistent; that is the job of the 'buildtag' analyzer in the vet suite.)


Default: on.

Package documentation: [plusbuild](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#plusbuild)

<a id='printf'></a>
## `printf`: check consistency of Printf format strings and arguments

The check applies to calls of the formatting functions such as [fmt.Printf](/fmt#Printf) and [fmt.Sprintf](/fmt#Sprintf), as well as any detected wrappers of those functions such as [log.Printf](/log#Printf). It reports a variety of mistakes such as syntax errors in the format string and mismatches (of number and type) between the verbs and their arguments.

See the documentation of the fmt package for the complete set of format operators and their operand types.


Default: on.

Package documentation: [printf](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/printf)

<a id='rangeint'></a>
## `rangeint`: replace 3-clause for loops with for-range over integers

The rangeint analyzer suggests replacing traditional for loops such as

	for i := 0; i < n; i++ { ... }

with the more idiomatic Go 1.22 style:

	for i := range n { ... }

This transformation is applied only if (a) the loop variable is not modified within the loop body and (b) the loop's limit expression is not modified within the loop, as \`for range\` evaluates its operand only once.


Default: on.

Package documentation: [rangeint](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#rangeint)

<a id='recursiveiter'></a>
## `recursiveiter`: check for inefficient recursive iterators

This analyzer reports when a function that returns an iterator (iter.Seq or iter.Seq2) calls itself as the operand of a range statement, as this is inefficient.

When implementing an iterator (e.g. iter.Seq\[T]) for a recursive data type such as a tree or linked list, it is tempting to recursively range over the iterator for each child element.

Here's an example of a naive iterator over a binary tree:

	type tree struct {
		value       int
		left, right *tree
	}

	func (t *tree) All() iter.Seq[int] {
		return func(yield func(int) bool) {
			if t != nil {
				for elem := range t.left.All() { // "inefficient recursive iterator"
					if !yield(elem) {
						return
					}
				}
				if !yield(t.value) {
					return
				}
				for elem := range t.right.All() { // "inefficient recursive iterator"
					if !yield(elem) {
						return
					}
				}
			}
		}
	}

Though it correctly enumerates the elements of the tree, it hides a significant performance problem--two, in fact. Consider a balanced tree of N nodes. Iterating the root node will cause All to be called once on every node of the tree. This results in a chain of nested active range-over-func statements when yield(t.value) is called on a leaf node.

The first performance problem is that each range-over-func statement must typically heap-allocate a variable, so iteration of the tree allocates as many variables as there are elements in the tree, for a total of O(N) allocations, all unnecessary.

The second problem is that each call to yield for a leaf of the tree causes each of the enclosing range loops to receive a value, which they then immediately pass on to their respective yield function. This results in a chain of log(N) dynamic yield calls per element, a total of O(N\*log N) dynamic calls overall, when only O(N) are necessary.

A better implementation strategy for recursive iterators is to first define the "every" operator for your recursive data type, where every(f) reports whether an arbitrary predicate f(x) is true for every element x in the data type. For our tree, the every function would be:

	func (t *tree) every(f func(int) bool) bool {
		return t == nil ||
			t.left.every(f) && f(t.value) && t.right.every(f)
	}

For example, this use of the every operator prints whether every element in the tree is an even number:

	even := func(x int) bool { return x&1 == 0 }
	println(t.every(even))

Then the iterator can be simply expressed as a trivial wrapper around the every operator:

	func (t *tree) All() iter.Seq[int] {
		return func(yield func(int) bool) {
			_ = t.every(yield)
		}
	}

In effect, tree.All computes whether yield returns true for each element, short-circuiting if it ever returns false, then discards the final boolean result.

This has much better performance characteristics: it makes one dynamic call per element of the tree, and it doesn't heap-allocate anything. It is also clearer.


Default: on.

Package documentation: [recursiveiter](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/recursiveiter)

<a id='reflecttypefor'></a>
## `reflecttypefor`: replace reflect.TypeOf(x) with TypeFor[T]()

This analyzer suggests fixes to replace uses of reflect.TypeOf(x) with reflect.TypeFor, introduced in go1.22, when the desired runtime type is known at compile time, for example:

	reflect.TypeOf(uint32(0))        -> reflect.TypeFor[uint32]()
	reflect.TypeOf((*ast.File)(nil)) -> reflect.TypeFor[*ast.File]()

It also offers a fix to simplify the constructions below, which use reflect.TypeOf to return the runtime type for an interface type,

	reflect.TypeOf((*io.Reader)(nil)).Elem()

or:

	reflect.TypeOf([]io.Reader(nil)).Elem()

to:

	reflect.TypeFor[io.Reader]()

No fix is offered in cases when the runtime type is dynamic, such as:

	var r io.Reader = ...
	reflect.TypeOf(r)

or when the operand has potential side effects.


Default: on.

Package documentation: [reflecttypefor](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#reflecttypefor)

<a id='shadow'></a>
## `shadow`: check for possible unintended shadowing of variables

This analyzer check for shadowed variables. A shadowed variable is a variable declared in an inner scope with the same name and type as a variable in an outer scope, and where the outer variable is mentioned after the inner one is declared.

(This definition can be refined; the module generates too many false positives and is not yet enabled by default.)

For example:

	func BadRead(f *os.File, buf []byte) error {
		var err error
		for {
			n, err := f.Read(buf) // shadows the function variable 'err'
			if err != nil {
				break // causes return of wrong value
			}
			foo(buf)
		}
		return err
	}


Default: off. Enable by setting `"analyses": {"shadow": true}`.

Package documentation: [shadow](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shadow)

<a id='shift'></a>
## `shift`: check for shifts that equal or exceed the width of the integer



Default: on.

Package documentation: [shift](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shift)

<a id='sigchanyzer'></a>
## `sigchanyzer`: check for unbuffered channel of os.Signal

This checker reports call expression of the form

	signal.Notify(c <-chan os.Signal, sig ...os.Signal),

where c is an unbuffered channel, which can be at risk of missing the signal.


Default: on.

Package documentation: [sigchanyzer](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sigchanyzer)

<a id='simplifycompositelit'></a>
## `simplifycompositelit`: check for composite literal simplifications

An array, slice, or map composite literal of the form:

	[]T{T{}, T{}}

will be simplified to:

	[]T{{}, {}}

This is one of the simplifications that "gofmt -s" applies.

This analyzer ignores generated code.


Default: on.

Package documentation: [simplifycompositelit](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifycompositelit)

<a id='simplifyrange'></a>
## `simplifyrange`: check for range statement simplifications

A range of the form:

	for x, _ = range v {...}

will be simplified to:

	for x = range v {...}

A range of the form:

	for _ = range v {...}

will be simplified to:

	for range v {...}

This is one of the simplifications that "gofmt -s" applies.

This analyzer ignores generated code.


Default: on.

Package documentation: [simplifyrange](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyrange)

<a id='simplifyslice'></a>
## `simplifyslice`: check for slice simplifications

A slice expression of the form:

	s[a:len(s)]

will be simplified to:

	s[a:]

This is one of the simplifications that "gofmt -s" applies.

This analyzer ignores generated code.


Default: on.

Package documentation: [simplifyslice](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyslice)

<a id='slicescontains'></a>
## `slicescontains`: replace loops with slices.Contains or slices.ContainsFunc

The slicescontains analyzer simplifies loops that check for the existence of an element in a slice. It replaces them with calls to \`slices.Contains\` or \`slices.ContainsFunc\`, which were added in Go 1.21.

If the expression for the target element has side effects, this transformation will cause those effects to occur only once, not once per tested slice element.


Default: on.

Package documentation: [slicescontains](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicescontains)

<a id='slicesdelete'></a>
## `slicesdelete`: replace append-based slice deletion with slices.Delete

The slicesdelete analyzer suggests replacing the idiom

	s = append(s[:i], s[j:]...)

with the more explicit

	s = slices.Delete(s, i, j)

introduced in Go 1.21.

This analyzer is disabled by default. The \`slices.Delete\` function zeros the elements between the new length and the old length of the slice to prevent memory leaks, which is a subtle difference in behavior compared to the append-based idiom; see [https://go.dev/issue/73686](https://go.dev/issue/73686).


Default: off. Enable by setting `"analyses": {"slicesdelete": true}`.

Package documentation: [slicesdelete](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicesdelete)

<a id='slicessort'></a>
## `slicessort`: replace sort.Slice with slices.Sort for basic types

The slicessort analyzer simplifies sorting slices of basic ordered types. It replaces

	sort.Slice(s, func(i, j int) bool { return s[i] < s[j] })

with the simpler \`slices.Sort(s)\`, which was added in Go 1.21.


Default: on.

Package documentation: [slicessort](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicessort)

<a id='slog'></a>
## `slog`: check for invalid structured logging calls

The slog checker looks for calls to functions from the log/slog package that take alternating key-value pairs. It reports calls where an argument in a key position is neither a string nor a slog.Attr, and where a final key is missing its value. For example,it would report

	slog.Warn("message", 11, "k") // slog.Warn arg "11" should be a string or a slog.Attr

and

	slog.Info("message", "k1", v1, "k2") // call to slog.Info missing a final value


Default: on.

Package documentation: [slog](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/slog)

<a id='sortslice'></a>
## `sortslice`: check the argument type of sort.Slice

sort.Slice requires an argument of a slice type. Check that the interface{} value passed to sort.Slice is actually a slice.


Default: on.

Package documentation: [sortslice](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sortslice)

<a id='stditerators'></a>
## `stditerators`: use iterators instead of Len/At-style APIs

This analyzer suggests a fix to replace each loop of the form:

	for i := 0; i < x.Len(); i++ {
		use(x.At(i))
	}

or its "for elem := range x.Len()" equivalent by a range loop over an iterator offered by the same data type:

	for elem := range x.All() {
		use(x.At(i)
	}

where x is one of various well-known types in the standard library.


Default: on.

Package documentation: [stditerators](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stditerators)

<a id='stdmethods'></a>
## `stdmethods`: check signature of methods of well-known interfaces

Sometimes a type may be intended to satisfy an interface but may fail to do so because of a mistake in its method signature. For example, the result of this WriteTo method should be (int64, error), not error, to satisfy io.WriterTo:

	type myWriterTo struct{...}
	func (myWriterTo) WriteTo(w io.Writer) error { ... }

This check ensures that each method whose name matches one of several well-known interface methods from the standard library has the correct signature for that interface.

Checked method names include:

	Format GobEncode GobDecode MarshalJSON MarshalXML
	Peek ReadByte ReadFrom ReadRune Scan Seek
	UnmarshalJSON UnreadByte UnreadRune WriteByte
	WriteTo


Default: on.

Package documentation: [stdmethods](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdmethods)

<a id='stdversion'></a>
## `stdversion`: report uses of too-new standard library symbols

The stdversion analyzer reports references to symbols in the standard library that were introduced by a Go release higher than the one in force in the referring file. (Recall that the file's Go version is defined by the 'go' directive its module's go.mod file, or by a "//go:build go1.X" build tag at the top of the file.)

The analyzer does not report a diagnostic for a reference to a "too new" field or method of a type that is itself "too new", as this may have false positives, for example if fields or methods are accessed through a type alias that is guarded by a Go version constraint.


Default: on.

Package documentation: [stdversion](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdversion)

<a id='stringintconv'></a>
## `stringintconv`: check for string(int) conversions

This checker flags conversions of the form string(x) where x is an integer (but not byte or rune) type. Such conversions are discouraged because they return the UTF-8 representation of the Unicode code point x, and not a decimal string representation of x as one might expect. Furthermore, if x denotes an invalid code point, the conversion cannot be statically rejected.

For conversions that intend on using the code point, consider replacing them with string(rune(x)). Otherwise, strconv.Itoa and its equivalents return the string representation of the value in the desired base.


Default: on.

Package documentation: [stringintconv](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stringintconv)

<a id='stringsbuilder'></a>
## `stringsbuilder`: replace += with strings.Builder

This analyzer replaces repeated string += string concatenation operations with calls to Go 1.10's strings.Builder.

For example:

	var s = "["
	for x := range seq {
		s += x
		s += "."
	}
	s += "]"
	use(s)

is replaced by:

	var s strings.Builder
	s.WriteString("[")
	for x := range seq {
		s.WriteString(x)
		s.WriteString(".")
	}
	s.WriteString("]")
	use(s.String())

This avoids quadratic memory allocation and improves performance.

The analyzer requires that all references to s before the final uses are += operations. To avoid warning about trivial cases, at least one must appear within a loop. The variable s must be a local variable, not a global or parameter.

All uses of the finished string must come after the last += operation. Each such use will be replaced by a call to strings.Builder's String method. (These may appear within an intervening loop or function literal, since even if s.String() is called repeatedly, it does not allocate memory.)

Often the addend is a call to fmt.Sprintf, as in this example:

	var s string
	for x := range seq {
		s += fmt.Sprintf("%v", x)
	}

which, once the suggested fix is applied, becomes:

	var s strings.Builder
	for x := range seq {
		s.WriteString(fmt.Sprintf("%v", x))
	}

The WriteString call can be further simplified to the more efficient fmt.Fprintf(&s, "%v", x), avoiding the allocation of an intermediary. However, stringsbuilder does not perform this simplification; it requires staticcheck analyzer QF1012. (See [https://go.dev/issue/76918](https://go.dev/issue/76918).)


Default: on.

Package documentation: [stringsbuilder](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringbuilder)

<a id='stringscut'></a>
## `stringscut`: replace strings.Index etc. with strings.Cut

This analyzer replaces certain patterns of use of [strings.Index](/strings#Index) and string slicing by [strings.Cut](/strings#Cut), added in go1.18.

For example:

	idx := strings.Index(s, substr)
	if idx >= 0 {
	    return s[:idx]
	}

is replaced by:

	before, _, ok := strings.Cut(s, substr)
	if ok {
	    return before
	}

And:

	idx := strings.Index(s, substr)
	if idx >= 0 {
	    return
	}

is replaced by:

	found := strings.Contains(s, substr)
	if found {
	    return
	}

It also handles variants using [strings.IndexByte](/strings#IndexByte) instead of Index, or the bytes package instead of strings.

Fixes are offered only in cases in which there are no potential modifications of the idx, s, or substr expressions between their definition and use.


Default: on.

Package documentation: [stringscut](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscut)

<a id='stringscutprefix'></a>
## `stringscutprefix`: replace HasPrefix/TrimPrefix with CutPrefix

The stringscutprefix analyzer simplifies a common pattern where code first checks for a prefix with \`strings.HasPrefix\` and then removes it with \`strings.TrimPrefix\`. It replaces this two-step process with a single call to \`strings.CutPrefix\`, introduced in Go 1.20. The analyzer also handles the equivalent functions in the \`bytes\` package.

For example, this input:

	if strings.HasPrefix(s, prefix) {
	    use(strings.TrimPrefix(s, prefix))
	}

is fixed to:

	if after, ok := strings.CutPrefix(s, prefix); ok {
	    use(after)
	}

The analyzer also offers fixes to use CutSuffix in a similar way. This input:

	if strings.HasSuffix(s, suffix) {
	    use(strings.TrimSuffix(s, suffix))
	}

is fixed to:

	if before, ok := strings.CutSuffix(s, suffix); ok {
	    use(before)
	}


Default: on.

Package documentation: [stringscutprefix](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscutprefix)

<a id='stringsseq'></a>
## `stringsseq`: replace ranging over Split/Fields with SplitSeq/FieldsSeq

The stringsseq analyzer improves the efficiency of iterating over substrings. It replaces

	for range strings.Split(...)

with the more efficient

	for range strings.SplitSeq(...)

which was added in Go 1.24 and avoids allocating a slice for the substrings. The analyzer also handles strings.Fields and the equivalent functions in the bytes package.


Default: on.

Package documentation: [stringsseq](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringsseq)

<a id='structtag'></a>
## `structtag`: check that struct field tags conform to reflect.StructTag.Get

Also report certain struct tags (json, xml) used with unexported fields.


Default: on.

Package documentation: [structtag](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/structtag)

<a id='testingcontext'></a>
## `testingcontext`: replace context.WithCancel with t.Context in tests

The testingcontext analyzer simplifies context management in tests. It replaces the manual creation of a cancellable context,

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

with a single call to t.Context(), which was added in Go 1.24.

This change is only suggested if the \`cancel\` function is not used for any other purpose.


Default: on.

Package documentation: [testingcontext](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#testingcontext)

<a id='testinggoroutine'></a>
## `testinggoroutine`: report calls to (*testing.T).Fatal from goroutines started by a test

Functions that abruptly terminate a test, such as the Fatal, Fatalf, FailNow, and Skip{,f,Now} methods of \*testing.T, must be called from the test goroutine itself. This checker detects calls to these functions that occur within a goroutine started by the test. For example:

	func TestFoo(t *testing.T) {
	    go func() {
	        t.Fatal("oops") // error: (*T).Fatal called from non-test goroutine
	    }()
	}


Default: on.

Package documentation: [testinggoroutine](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/testinggoroutine)

<a id='tests'></a>
## `tests`: check for common mistaken usages of tests and examples

The tests checker walks Test, Benchmark, Fuzzing and Example functions checking malformed names, wrong signatures and examples documenting non-existent identifiers.

Please see the documentation for package testing in golang.org/pkg/testing for the conventions that are enforced for Tests, Benchmarks, and Examples.


Default: on.

Package documentation: [tests](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/tests)

<a id='timeformat'></a>
## `timeformat`: check for calls of (time.Time).Format or time.Parse with 2006-02-01

The timeformat checker looks for time formats with the 2006-02-01 (yyyy-dd-mm) format. Internationally, "yyyy-dd-mm" does not occur in common calendar date standards, and so it is more likely that 2006-01-02 (yyyy-mm-dd) was intended.


Default: on.

Package documentation: [timeformat](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/timeformat)

<a id='unmarshal'></a>
## `unmarshal`: report passing non-pointer or non-interface values to unmarshal

The unmarshal analysis reports calls to functions such as json.Unmarshal in which the argument type is not a pointer or an interface.


Default: on.

Package documentation: [unmarshal](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unmarshal)

<a id='unreachable'></a>
## `unreachable`: check for unreachable code

The unreachable analyzer finds statements that execution can never reach because they are preceded by a return statement, a call to panic, an infinite loop, or similar constructs.


Default: on.

Package documentation: [unreachable](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unreachable)

<a id='unsafefuncs'></a>
## `unsafefuncs`: replace unsafe pointer arithmetic with function calls

The unsafefuncs analyzer simplifies pointer arithmetic expressions by replacing them with calls to helper functions such as unsafe.Add, added in Go 1.17.

Example:

	unsafe.Pointer(uintptr(ptr) + uintptr(n))

where ptr is an unsafe.Pointer, is replaced by:

	unsafe.Add(ptr, n)


Default: on.

Package documentation: [unsafefuncs](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#unsafefuncs)

<a id='unsafeptr'></a>
## `unsafeptr`: check for invalid conversions of uintptr to unsafe.Pointer

The unsafeptr analyzer reports likely incorrect uses of unsafe.Pointer to convert integers to pointers. A conversion from uintptr to unsafe.Pointer is invalid if it implies that there is a uintptr-typed word in memory that holds a pointer value, because that word will be invisible to stack copying and to the garbage collector.


Default: on.

Package documentation: [unsafeptr](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unsafeptr)

<a id='unusedfunc'></a>
## `unusedfunc`: check for unused functions, methods, etc

The unusedfunc analyzer reports functions and methods that are never referenced outside of their own declaration.

A function is considered unused if it is unexported and not referenced (except within its own declaration).

A method is considered unused if it is unexported, not referenced (except within its own declaration), and its name does not match that of any method of an interface type declared within the same package.

The tool may report false positives in some situations, for example:

  - for a declaration of an unexported function that is referenced from another package using the go:linkname mechanism, if the declaration's doc comment does not also have a go:linkname comment.

    (Such code is in any case strongly discouraged: linkname annotations, if they must be used at all, should be used on both the declaration and the alias.)

  - for compiler intrinsics in the "runtime" package that, though never referenced, are known to the compiler and are called indirectly by compiled object code.

  - for functions called only from assembly.

  - for functions called only from files whose build tags are not selected in the current build configuration.

Since these situations are relatively common in the low-level parts of the runtime, this analyzer ignores the standard library. See [https://go.dev/issue/71686](https://go.dev/issue/71686) and [https://go.dev/issue/74130](https://go.dev/issue/74130) for further discussion of these limitations.

The unusedfunc algorithm is not as precise as the golang.org/x/tools/cmd/deadcode tool, but it has the advantage that it runs within the modular analysis framework, enabling near real-time feedback within gopls.

The unusedfunc analyzer also reports unused types, vars, and constants. Enums--constants defined with iota--are ignored since even the unused values must remain present to preserve the logical ordering.


Default: on.

Package documentation: [unusedfunc](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedfunc)

<a id='unusedparams'></a>
## `unusedparams`: check for unused parameters of functions

The unusedparams analyzer checks functions to see if there are any parameters that are not being used.

To ensure soundness, it ignores:

  - "address-taken" functions, that is, functions that are used as a value rather than being called directly; their signatures may be required to conform to a func type.
  - exported functions or methods, since they may be address-taken in another package.
  - unexported methods whose name matches an interface method declared in the same package, since the method's signature may be required to conform to the interface type.
  - functions with empty bodies, or containing just a call to panic.
  - parameters that are unnamed, or named "\_", the blank identifier.

The analyzer suggests a fix of replacing the parameter name by "\_", but in such cases a deeper fix can be obtained by invoking the "Refactor: remove unused parameter" code action, which will eliminate the parameter entirely, along with all corresponding arguments at call sites, while taking care to preserve any side effects in the argument expressions; see [https://github.com/golang/tools/releases/tag/gopls%2Fv0.14](https://github.com/golang/tools/releases/tag/gopls%2Fv0.14).

This analyzer ignores generated code.


Default: on.

Package documentation: [unusedparams](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedparams)

<a id='unusedresult'></a>
## `unusedresult`: check for unused results of calls to some functions

Some functions like fmt.Errorf return a result and have no side effects, so it is always a mistake to discard the result. Other functions may return an error that must not be ignored, or a cleanup operation that must be called. This analyzer reports calls to functions like these when the result of the call is ignored.

The set of functions may be controlled using flags.


Default: on.

Package documentation: [unusedresult](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedresult)

<a id='unusedvariable'></a>
## `unusedvariable`: check for unused variables and suggest fixes



Default: on.

Package documentation: [unusedvariable](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedvariable)

<a id='unusedwrite'></a>
## `unusedwrite`: checks for unused writes

The analyzer reports instances of writes to struct fields and arrays that are never read. Specifically, when a struct object or an array is copied, its elements are copied implicitly by the compiler, and any element write to this copy does nothing with the original object.

For example:

	type T struct { x int }

	func f(input []T) {
		for i, v := range input {  // v is a copy
			v.x = i  // unused write to field x
		}
	}

Another example is about non-pointer receiver:

	type T struct { x int }

	func (t T) f() {  // t is a copy
		t.x = i  // unused write to field x
	}


Default: on.

Package documentation: [unusedwrite](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedwrite)

<a id='waitgroup'></a>
## `waitgroup`: check for misuses of sync.WaitGroup

This analyzer detects mistaken calls to the (\*sync.WaitGroup).Add method from inside a new goroutine, causing Add to race with Wait:

	// WRONG
	var wg sync.WaitGroup
	go func() {
	        wg.Add(1) // "WaitGroup.Add called from inside new goroutine"
	        defer wg.Done()
	        ...
	}()
	wg.Wait() // (may return prematurely before new goroutine starts)

The correct code calls Add before starting the goroutine:

	// RIGHT
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		defer wg.Done()
		...
	}()
	wg.Wait()


Default: on.

Package documentation: [waitgroup](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/waitgroup)

<a id='waitgroupgo'></a>
## `waitgroupgo`: replace wg.Add(1)/go/wg.Done() with wg.Go

The waitgroupgo analyzer simplifies goroutine management with \`sync.WaitGroup\`. It replaces the common pattern

	wg.Add(1)
	go func() {
		defer wg.Done()
		...
	}()

with a single call to

	wg.Go(func(){ ... })

which was added in Go 1.25.


Default: on.

Package documentation: [waitgroupgo](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#waitgroupgo)

<a id='writestring'></a>
## `writestring`: detect inefficient string concatenation in uses of WriteString

The writestring analyzer offers to replace a call to WriteString(x + y) by two calls WriteString(x); WriteString(y). This is more efficient because it avoids the additional memory allocation produced by string concatenation; instead we just write each string into the buffer directly.

It explicitly looks for calls to certain well-known writers such as bytes.Buffer, strings.Builder and bufio.Writer. The analyzer will not suggest a fix for calls to, say, (\*os.File).WriteString, because for certain kinds of file such as a UDP socket, it could split a single message into two. Similarly it does not offer fixes when the type of the writer is unknown (as in calls to io.WriteString).

For example:

	func f(a string, b string) string {
		 var s strings.Builder
		 s.WriteString(a+b)
		 return s.String()
	}

would become:

	func f(a string, b string) string {
		var s strings.Builder
		s.WriteString(a)
		s.WriteString(b)
		return s.String()
	}


Default: on.

Package documentation: [writestring](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/writestring)

<a id='yield'></a>
## `yield`: report calls to yield where the result is ignored

After a yield function returns false, the caller should not call the yield function again; generally the iterator should return promptly.

This example fails to check the result of the call to yield, causing this analyzer to report a diagnostic:

	yield(1) // yield may be called again (on L2) after returning false
	yield(2)

The corrected code is either this:

	if yield(1) { yield(2) }

or simply:

	_ = yield(1) && yield(2)

It is not always a mistake to ignore the result of yield. For example, this is a valid single-element iterator:

	yield(1) // ok to ignore result
	return

It is only a mistake when the yield call that returned false may be followed by another call.


Default: on.

Package documentation: [yield](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/yield)

<!-- END Analyzers: DO NOT MANUALLY EDIT THIS SECTION -->


================================================
FILE: gopls/doc/assets/assets.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package assets is an empty package to appease "go test ./...",
// as run by our CI builders, which doesn't like an empty module.
package assets


================================================
FILE: gopls/doc/assets/go.mod
================================================
// This module contains no Go code, but serves to carve out a hole in
// its parent module to avoid bloating it with large image files that
// would otherwise be downloaded by "go install golang.org/x/tools/gopls@latest".

module golang.org/x/tools/gopls/doc/assets

go 1.25.0


================================================
FILE: gopls/doc/codelenses.md
================================================
---
title: "Gopls: Code lenses"
---

A "code lens" is a command associated with a range of a source file.
The VS Code manual describes code lenses as
"[actionable, contextual information, interspersed in your source
code](https://code.visualstudio.com/blogs/2017/02/12/code-lens-roundup)".
The LSP [`textDocument/codeLens`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_codeLens) operation requests the
current set of code lenses for a file.

Gopls generates code lenses from a number of sources.
This document describes them.

They can be enabled and disabled using the
[`codelenses`](settings.md#codelenses) setting.
Their features are subject to change.

Client support:
- **VS Code**: Code Lenses appear as small text links above a line of source code.
- **Emacs + eglot**: Not supported, but prototype exists at https://github.com/joaotavora/eglot/pull/71.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls codelens`. For example, `gopls codelens -exec file.go:123 "run test"` runs the test at the specified line.


<!-- This portion is generated by doc/generate from the ../internal/settings package. -->
<!-- BEGIN Lenses: DO NOT MANUALLY EDIT THIS SECTION -->
## `generate`: Run `go generate`


This codelens source annotates any `//go:generate` comments
with commands to run `go generate` in this directory, on
all directories recursively beneath this one.

See [Generating code](https://go.dev/blog/generate) for
more details.


Default: on

File type: Go

## `regenerate_cgo`: Re-generate cgo declarations


This codelens source annotates an `import "C"` declaration
with a command to re-run the [cgo
command](https://pkg.go.dev/cmd/cgo) to regenerate the
corresponding Go declarations.

Use this after editing the C code in comments attached to
the import, or in C header files included by it.


Default: on

File type: Go

## `test`: Run tests and benchmarks


This codelens source annotates each `Test` and `Benchmark`
function in a `*_test.go` file with a command to run it.

This source is off by default because VS Code has
a client-side custom UI for testing, and because progress
notifications are not a great UX for streamed test output.
See:
- golang/go#67400 for a discussion of this feature.
- https://github.com/joaotavora/eglot/discussions/1402
  for an alternative approach.


Default: off

File type: Go

## `run_govulncheck`: Run govulncheck (legacy)


This codelens source annotates the `module` directive in a go.mod file
with a command to run Govulncheck asynchronously.

[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that
computes the set of functions reachable within your application, including
dependencies; queries a database of known security vulnerabilities; and
reports any potential problems it finds.


Default: on

File type: go.mod

## `tidy`: Tidy go.mod file


This codelens source annotates the `module` directive in a
go.mod file with a command to run [`go mod
tidy`](https://go.dev/ref/mod#go-mod-tidy), which ensures
that the go.mod file matches the source code in the module.


Default: on

File type: go.mod

## `upgrade_dependency`: Update dependencies


This codelens source annotates the `module` directive in a
go.mod file with commands to:

- check for available upgrades,
- upgrade direct dependencies, and
- upgrade all dependencies transitively.


Default: on

File type: go.mod

## `vendor`: Update vendor directory


This codelens source annotates the `module` directive in a
go.mod file with a command to run [`go mod
vendor`](https://go.dev/ref/mod#go-mod-vendor), which
creates or updates the directory named `vendor` in the
module root so that it contains an up-to-date copy of all
necessary package dependencies.


Default: on

File type: go.mod

## `vulncheck`: Run govulncheck

**This setting is experimental and may be deleted.**


This codelens source annotates the `module` directive in a go.mod file
with a command to run govulncheck synchronously.

[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that
computes the set of functions reachable within your application, including
dependencies; queries a database of known security vulnerabilities; and
reports any potential problems it finds.


Default: off

File type: go.mod

<!-- END Lenses: DO NOT MANUALLY EDIT THIS SECTION -->


================================================
FILE: gopls/doc/command-line.md
================================================
---
title: "Gopls: Command-line interface"
---

The `gopls` command provides a number of subcommands that expose much
of the server's functionality. However, the interface is currently
**experimental** and **subject to change at any point.**
It is not efficient, complete, flexible, or officially supported.

Its primary use is as a debugging aid.
For example, this command reports the location of references to the
symbol at the specified file/line/column:

```
$ gopls references ./gopls/main.go:35:8
Log: Loading packages...
Info: Finished loading packages.
/home/gopher/xtools/go/packages/gopackages/main.go:27:7-11
/home/gopher/xtools/gopls/internal/cmd/integration_test.go:1062:7-11
/home/gopher/xtools/gopls/internal/test/integration/bench/bench_test.go:59:8-12
/home/gopher/xtools/gopls/internal/test/integration/regtest.go:140:8-12
/home/gopher/xtools/gopls/main.go:35:7-11
```

See https://go.dev/issue/63693 for a discussion of its future.

Learn about available commands and flags by running `gopls help`.

Positions within files are specified as `file.go:line:column` triples,
where the line and column start at 1, and columns are measured in
bytes of the UTF-8 encoding.
Alternatively, positions may be specified by the byte offset within
the UTF-8 encoding of the file, starting from zero, for example
`file.go:#1234`.
(When working in non-ASCII files, beware that your editor may report a
position's offset within its file using a different measure such as
UTF-16 codes, Unicode code points, or graphemes).


================================================
FILE: gopls/doc/contributing.md
================================================
---
title: "Gopls: Contributing"
---

Contributions are welcome! However, development is fast moving,
and we are limited in our capacity to review contributions.
So, before sending a CL, please please please:

- **file an issue** for a bug or feature request, if one does not
  exist already. This allows us to identify redundant requests, or to
  merge a specific problem into a more general one, and to assess the
  importance of the problem.
- **claim it for yourself** by commenting on the issue or, if you are
  able, by assigning the issue to yourself. This helps us avoid two
  people working on the same problem.
- **propose an implementation plan** in the issue tracker for CLs of
  any complexity. It is much more efficient to discuss the plan at a
  high level before we start getting bogged down in the details of
  a code review.

When you send a CL, it should include:

- a **CL description** that summarizes the change,
  motivates why it is necessary,
  explains it at a high level,
  contrasts it with more obvious or simpler approaches, and
  links to relevant issues;
- **tests** (integration tests or marker tests);
- **documentation**, for new or modified features; and
- **release notes**, for new features or significant changes.

During code review, please address all reviewer comments.
Some comments result in straightforward code changes;
others demand a more complex response.
When a reviewer asks a question, the best response is
often not to respond to it directly, but to change the
code to avoid raising the question,
for example by making the code self-explanatory.
It's fine to disagree with a comment,
point out a reviewer's mistake,
or offer to address a comment in a follow-up change,
leaving a `TODO` comment in the current CL.
But please don't dismiss or quietly ignore a comment without action,
as it may lead reviewers to repeat themselves,
or to serious problems being neglected.

For more detail, see the Go project's
[contribution guidelines](https://golang.org/doc/contribute.html).

## Finding issues

All `gopls` issues are labeled as such (see the [`gopls` label][issue-gopls]).
Issues that are suitable for contributors are additionally tagged with the
[`help-wanted` label][issue-wanted].

Before you begin working on an issue, please leave a comment that you are
claiming it.

## Getting started

[![PkgGoDev](https://pkg.go.dev/badge/golang.org/x/tools/gopls/internal)](https://pkg.go.dev/golang.org/x/tools/gopls/internal)

Most of the `gopls` logic is in the `golang.org/x/tools/gopls/internal` directory.
See [design/implementation.md](./design/implementation.md) for an overview of the code organization.

## Build

To build a version of `gopls` with your changes applied:

```bash
cd /path/to/tools/gopls
go install
```

To confirm that you are testing with the correct `gopls` version, check that
your `gopls` version looks like this:

```bash
$ gopls version
golang.org/x/tools/gopls master
    golang.org/x/tools/gopls@(devel)
```

## Getting help

The best way to contact the gopls team directly is via the
[#gopls-dev](https://app.slack.com/client/T029RQSE6/CRWSN9NCD) channel on the
gophers slack. Please feel free to ask any questions about your contribution or
about contributing in general.


## Error handling

It is important for the user experience that, whenever practical,
minor logic errors in a particular feature don't cause the server to
crash.

The representation of a Go program is complex. The import graph of
package metadata, the syntax trees of parsed files, and their
associated type information together form a huge API surface area.
Even when the input is valid, there are many edge cases to consider,
and this grows by an order of magnitude when you consider missing
imports, parse errors, and type errors.

What should you do when your logic must handle an error that you
believe "can't happen"?

- If it's possible to return an error, then use the `bug.Errorf`
  function to return an error to the user, but also record the bug in
  gopls' cache so that it is less likely to be ignored.

- If it's safe to proceed, you can call `bug.Reportf` to record the
  error and continue as normal.

- If there's no way to proceed, call `bug.Fatalf` to record the error
  and then stop the program with `log.Fatalf`. You can also use
  `bug.Panicf` if there's a chance that a recover handler might save
  the situation.

- Only if you can prove locally that an error is impossible should you
  call `log.Fatal`. If the error may happen for some input, however
  unlikely, then you should use one of the approaches above. Also, if
  the proof of safety depends on invariants broadly distributed across
  the code base, then you should instead use `bug.Panicf`.

Note also that panicking is preferable to `log.Fatal` because it
allows VS Code's crash reporting to recognize and capture the stack.

Bugs reported through `bug.Errorf` and friends are retrieved using the
`gopls bug` command, which opens a GitHub Issue template and populates
it with a summary of each bug and its frequency.
The text of the bug is rather fastidiously printed to stdout to avoid
sharing user names and error message strings (which could contain
project identifiers) with GitHub.
Users are invited to share it if they are willing.

## Testing

The normal command you should use to run the tests after a change is:

```bash
gopls$ go test -short ./...
```

(The `-short` flag skips some slow-running ones. The trybot builders
run the complete set, on a wide range of platforms.)

Gopls tests are a mix of two kinds.

- [Marker tests](https://golang.org/x/tools/gopls/internal/test/marker) express each test scenario
  in a standalone text file that contains the target .go, go.mod, and
  go.work files, in which special annotations embedded in comments
  drive the test. These tests are generally easy to write and fast
  to iterate, but have limitations on what they can express.

- [Integration tests](https://golang.org/x/tools/gopls/internal/test/integration) are regular Go
  `func Test(*testing.T)` functions that make a series of calls to an
  API for a fake LSP-enabled client editor. The API allows you to open
  and edit a file, navigate to a definition, invoke other LSP
  operations, and assert properties about the state.

  Due to the asynchronous nature of the LSP, integration tests make
  assertions about states that the editor must achieve eventually,
  even when the program goes wrong quickly, it may take a while before
  the error is reported as a failure to achieve the desired state
  within several minutes. We recommend that you set
  `GOPLS_INTEGRATION_TEST_TIMEOUT=10s` to reduce the timeout for
  integration tests when debugging.

  When they fail, the integration tests print the log of the LSP
  session between client and server. Though verbose, they are very
  helpful for debugging once you know how to read them.

Don't hesitate to [reach out](#getting-help) to the gopls team if you
need help.

### CI

When you mail your CL and you or a fellow contributor assigns the
`Run-TryBot=1` label in Gerrit, the
[TryBots](https://golang.org/doc/contribute.html#trybots) will run tests in
both the `golang.org/x/tools` and `golang.org/x/tools/gopls` modules, as
described above.

Furthermore, an additional "gopls-CI" pass will be run by _Kokoro_, which is a
Jenkins-like Google infrastructure for running Dockerized tests. This allows us
to run gopls tests in various environments that would be difficult to add to
the TryBots. Notably, Kokoro runs tests on
[older Go versions](index.md#supported-go-versions) that are no longer supported
by the TryBots. Per that policy, support for these older Go versions is
best-effort, and test failures may be skipped rather than fixed.

Kokoro runs are triggered by the `Run-TryBot=1` label, just like TryBots, but
unlike TryBots they do not automatically re-run if the "gopls-CI" result is
removed in Gerrit. To force a re-run of the Kokoro CI on a CL containing the
`Run-TryBot=1` label, you can reply in Gerrit with the comment "kokoro rerun".

## Debugging

The easiest way to debug your change is to run a single `gopls` test with a
debugger.

See also [Troubleshooting](troubleshooting.md#troubleshooting).

### Debug Server

Gopls includes a built-in debug server that exposes metrics, traces, and
profiling information. Start it by passing the `-debug` flag, e.q. `gopls serve -debug=localhost:6060`. When using `:0`, gopls logs the assigned address to stderr.

You can also start the server in a running gopls process by executing a StartDebugging LSP command. In VS Code this is bound to the "Go: Start language server maintainer's interface" command.

**Key endpoints:**

| Endpoint | Description |
|----------|-------------|
| `/` | Overview of caches, sessions and clients |
| `/rpc/` | RPC statistics with latency and status codes |
| `/trace/` | Recent spans and operation traces |
| `/metrics/` | Prometheus-compatible metrics |
| `/memory` | Memory usage statistics |
| `/debug/pprof/` | Go pprof profiling |

### OpenTelemetry

Gopls supports periodical export of traces and metrics by POSTing JSON messages to an OpenTelemetry collector process such as Jaeger/Grafana. 
Use the `-otel` flag to specify the collector endpoint to enable exporting:

```bash
gopls serve -otel=http://localhost:4318
```

The data are discarded if no collector is listening at that address.

For example, to view traces locally with Jaeger:
```sh
$ podman run --rm --name jaeger \
  -p 16686:16686 \
  -p 4318:4318 \
  jaegertracing/all-in-one:1.76.0
```

Then open http://localhost:16686 to view traces.


[issue-gopls]: https://github.com/golang/go/issues?utf8=%E2%9C%93&q=is%3Aissue+is%3Aopen+label%3Agopls "gopls issues"
[issue-wanted]: https://github.com/golang/go/issues?utf8=✓&q=is%3Aissue+is%3Aopen+label%3Agopls+label%3A"help+wanted" "help wanted"

## Documentation

Each CL that adds or changes a feature should include, in addition to
a test that exercises the new behavior:

- a **release note** that briefly explains the change, and
- **comprehensive documentation** in the [index of features](features/).

The release note should go in the file named for the forthcoming
release, for example [release/v0.16.0.md](release/v0.16.0.md). (Create
the file if your feature is the first to be added after a release.)

## Design documentation

* [Integrating `gopls` with an editor](design/integrating.md)
* [Design requirements and decisions](design/design.md)
* [Implementation overview](design/implementation.md)


================================================
FILE: gopls/doc/daemon.md
================================================
---
title: "Gopls: Running as a daemon"
---

**Note: this feature is new. If you encounter bugs, please [file an
issue](troubleshooting.md#file-an-issue).**

If you just want to try this out, skip ahead to the [quickstart](#quickstart).

## Background: gopls execution modes

Gopls was originally implemented as an LSP sidecar: a process started by
editors or editor plugins, and communicated with using jsonrpc 2.0 over
stdin/stdout. By executing as a stateful process, gopls can maintain a
significant amount of cache and can eagerly perform analysis on the source code
being edited.

This execution mode does not work as well when there are many separate editor
processes or when editor processes are short-lived, as is often the case for
users of non-IDE editors such as Vim or Emacs. Having many processes means
having many caches, consuming a significant amount of system resources. Using
short-lived sessions means paying a start-up cost each time a session is
created.

To support these types of workflows, a new mode of gopls execution is supported
wherein a single, persistent, shared gopls "daemon" process is responsible for
managing all gopls sessions. In this mode, editors still start a gopls sidecar,
but this sidecar merely acts as a thin "forwarder", responsible for forwarding
the LSP to the shared gopls instance and recording metrics, logs, and rpc
traces.

## Quickstart

To use a shared gopls instance you must either manage the daemon process
yourself, or let the gopls forwarder processes start the shared daemon as
needed.

### Running with `-remote=auto`

Automatic management of the daemon is easiest, and can be done by passing the
flag `-remote=auto` to the gopls process started by your editor. This will
cause this process to auto-start the gopls daemon if needed, connect to it, and
forward the LSP. For example, here is a reasonable gopls invocation, that sets
some additional flags for easier [debugging](#debugging):

```bash
gopls -remote=auto -logfile=auto -debug=:0 -remote.debug=:0 -rpc.trace
```

Note that the shared gopls process will automatically shut down after one
minute with no connected clients.

### Managing the daemon manually

To manage the gopls daemon process via external means rather than having the
forwarders manage it, you must start a gopls daemon process with the
`-listen=<addr>` flag, and then pass `-remote=<addr>` to the gopls processes
started by your editor.

For example, to host the daemon on the TCP port `37374`, do:

```bash
gopls -listen=:37374 -logfile=auto -debug=:0
```

And then from the editor, run

```bash
gopls -remote=:37374 -logfile=auto -debug=:0 -rpc.trace
```

If you are on a POSIX system, you can also use unix domain sockets by prefixing
the flag values with `unix;`. For example:

```bash
gopls -listen="unix;/tmp/gopls-daemon-socket" -logfile=auto -debug=:0
```

And connect via:

```bash
gopls -remote="unix;/tmp/gopls-daemon-socket" -logfile=auto -debug=:0 -rpc.trace
```

(Note that these flag values MUST be enclosed in quotes, because ';' is a
special shell character. For this reason, this syntax is subject to change in
the future.)

## Debugging

Debugging a shared gopls session is more complicated than a singleton session,
because there are now two gopls processes involved with handling the LSP. Here
are some tips:

### Finding logfiles and debug addresses

When running in daemon mode, you can use the `gopls inspect sessions` command
to find the logfile and debug port for your gopls daemon instance (as well as
for all its connected clients). By default, this inspects the default daemon
(i.e. `-remote=auto`). To inspect a different daemon, use the `-remote` flag
explicitly: `gopls -remote=localhost:12345 inspect sessions`.

This works whether or not you have enabled `-remote.debug`.

### Traversing debug pages

When `-debug=:0` is passed to gopls, it runs a webserver that serves stateful
debug pages (see [troubleshooting.md](troubleshooting.md)). You can find the
actual port hosting these pages by either using the `gopls inspect sessions`
command, or by checking the start of the logfile -- it will be one of the first
log messages. For example, if using `-logfile=auto`, find the debug address by
checking `head /tmp/gopls-<pid>.log`.

By default, the gopls daemon is not started with `-debug`. To enable it, set
the `-remote.debug` flag on the forwarder instance, so that it invokes gopls
with `-debug` when starting the daemon.

The debug pages of the forwarder process will have a link to the debug pages of
the daemon server process. Correspondingly, the debug pages of the daemon
process will have a link to each of its clients.

This can help you find metrics, traces, and log files for all of the various
servers and clients.

### Using logfiles

The gopls daemon is started with logging disabled by default. To customize
this, pass `-remote.logfile` to the gopls forwarder. Using
`-remote.logfile=auto`, the daemon will log to a default location (on posix
systems: `/tmp/gopls-daemon-<pid>.log`).

The gopls daemon does not log session-scoped messages: those are instead
reflected back to the forwarder so that they can be accessed by the editor.
Daemon logs will only contain global messages, for example logs when sessions
connect and disconnect.

It is recommended to start the forwarder gopls process with `-rpc.trace`, so
that its logfile will contain rpc trace logs specific to the LSP session.

## Using multiple shared gopls instances

There may be environments where it is desirable to have more than one shared
gopls instance. If managing the daemon manually, this can be done by simply
choosing different `-listen` addresses for each distinct daemon process.

On POSIX systems, there is also support for automatic management of distinct
shared gopls processes: distinct daemons can be selected by passing
`-remote="auto;<id>"`. Any gopls forwarder passing the same value for `<id>`
will use the same shared daemon.

## FAQ

**Q: Why am I not saving as much memory as I expected when using a shared gopls?**

A: As described in [implementation.md](design/implementation.md), gopls has a
concept of view/session/cache. Each session and view map onto exactly one
editor session (because they contain things like edited but unsaved buffers).
The cache contains things that are independent of any editor session, and can
therefore be shared.

When, for example, three editor session are sharing a single gopls process,
they will share the cache but will each have their own session and view. The
memory savings in this mode, when compared to three separate gopls processes,
corresponds to the amount of cache overlap across sessions.

Because this hasn't mattered much in the past, it is likely that there is state
that can be moved out of the session/view, and into the cache, thereby
increasing the amount of memory savings in the shared mode.

**Q: How do I customize the daemon instance when using `-remote=auto`?**

The daemon may be customized using flags of the form `-remote.*` on the
forwarder gopls. This causes the forwarder to invoke gopls with these settings
when starting the daemon. As of writing, we expose the following configuration:

* `-remote.logfile`: the location of the daemon logfile
* `-remote.debug`: the daemon's debug address
* `-remote.listen.timeout`: the amount of time the daemon should wait for new
  connections while there are no current connections, before shutting down.
  Must be set to a valid `time.Duration` (e.g. `30s` or `5m`). If `0`, listen
  indefinitely. Default: `1m`.

Note that once the daemon is already running, setting these flags will not
change its configuration. These flags only matter for the forwarder process
that actually starts the daemon.


================================================
FILE: gopls/doc/default.tmpl
================================================
{{- /* For golang.org/x/website/cmd/golangorg */ -}}
{{define "layout"}}
{{doclayout .}}
{{end}}


================================================
FILE: gopls/doc/design/design.md
================================================
---
title: "Gopls: Design"
---

## _A note from the future_

What follows below is the original design document for gopls, aggregated from
various sources spanning 2018 and 2019. Since then, all of the features listed
below have been implemented, along with many others. The first two goals have
been achieved: gopls is a full implementation of the LSP, and the default
backend for VS Code Go and many other editors. The third goal has only been
partially realized: while gopls has gained many features, it is not extensible
in the sense used in this document: the only way to extend gopls is to modify
gopls. The fourth goal is not achieved: while some notable companies are able
to use gopls with Bazel, the experience is subpar, and the Go command is the
only officially supported build system.

On the other hand, two of the explicit non-goals have been reconsidered. One is
minor: syntax highlighting is now supported in the LSP by way of semantic
tokens. The other is major: as gopls gained popularity, it became apparent that
its memory footprint was a problem. The size of developer workspaces was
increasing faster than the RAM available in typically development environments
(particularly with containerized development). Gopls now uses a hybrid of
on-disk indexes and in-memory caches, described in more detail in our
[blog post on scalability](https://go.dev/blog/gopls-scalability).

Notably, in anticipating difficulties this doc turned out to be prescient.
Gopls has indeed struggled against the core standary library packages upon
which it is built, and its user experience is still limited by the LSP.
Nevertheless, sticking with the standard library and LSP was the right
approach, as despite our small team these decisions have helped gopls keep up
with the evolving Go language (i.e. generics), and to integrate with many new
text editors.

Gopls development continues, more than four years later, with a focus on
simplicity, reliability, and extensibility. The new, opt-in
[Go telemetry](https://github.com/golang/tools/releases/tag/gopls%2Fv0.14.0)
will help us attain a higher standard of stability in our releases than we've
been able to achieve through Github issues alone. Furthermore, telemetry will
allow us to focus on high-priority features, and deprecate historical
workarounds that burden the codebase. With greater velocity, we look forward
to working with the community on improved refactoring, static analysis, and
whatever else the future brings.

- _Rob Findley (rfindley@google.com), 2023_

## Goals

* `gopls` should **become the default editor backend** for the major editors used by Go programmers, fully supported by the Go team.
* `gopls` will be a **full implementation of LSP**, as described in the [LSP specification], to standardize as many of its features as possible.
* `gopls` will be **clean and extensible** so that it can encompass additional features in the future, allowing Go tooling to become best in class once more.
* `gopls` will **support alternate build systems and file layouts**, allowing Go development to be simpler and more powerful in any environment.

## Context

While Go has a number of excellent and useful command-line tools that enhance the developer experience, it has become clear that integrating these tools with IDEs can pose challenges.

Support of these tools has relied on the goodwill of community members, and they have been put under a large burden of support at times as the language, toolchain and environments change. As a result many tools have ceased to work, have had support problems, or become confusing with forks and replacements, or provided an experience that is not as good as it could be.
See the section below on [existing solutions](#existing-solutions) for more problems and details.

This is fine for tools used occasionally, but for core IDE features, this is not acceptable.
Autocompletion, jump to definition, formatting, and other such features should always work, as they are key for Go development.

The Go team will create an editor backend that works in any build system.
It will also be able to improve upon the latency of Go tools, since each tool will no longer have to individually run the type-checker on each invocation, instead there will be a long-running process and data can be shared between the definitions, completions, diagnostics, and other features.

By taking ownership of these tools and packaging them together in the form of gopls, the Go team will ensure that the Go development experience isn’t unnecessarily complicated for Go users.
Having one editor backend will simplify the lives of Go developers, the Go team, and the maintainers of Go editor plugins.

See Rebecca's excellent GopherCon keynote [talk] and [slides] for some more context.

## Non-Goals

* Command line speed

  Although gopls will have a command line mode, it will be optimized for long running and not command responsiveness, as such it may not be the right tool for things like CI systems.
  For such cases there will have to be an alternate tool using the same underlying libraries for consistency.

* Low memory environments

  In order to do a good job of processing large projects with very low latencies gopls will be holding a lot of information in memory.
  It is presumed that developers are normally working on systems with significant RAM and this will not be a problem.
  In general this is upheld by the large memory usage of existing IDE solutions (like IntelliJ)

* Syntax highlighting

  At the moment there is no editor that delegates this functionality to a separate binary, and no standard way of doing it.

## Existing solutions

Every year the Go team conducts a survey, asking developers about their experiences with the language.

One question that is asked is “How do you feel about your editor?”.

The responses told a very negative story. Some categorized quotes:

* Setup
  * "Hard to install and configure"
  * "Inadequate documentation"
* Performance
  * "Performance is very poor"
  * "Pretty slow in large projects"
* Reliability
  * "Features work one day, but not the next"
  * "Tooling is not updated with new language features"

Each editor has its own plugin that shells out to a variety of tools, many of which break with new Go releases or because they are no longer maintained.

The individual tools each have to do the work to understand the code and all its transitive dependencies.

Each feature is a different tool, with a different set of patterns for its command line, a different way to accept input and parse output, a different way of specifying source code locations.
To support its existing feature set, VSCode installed 24 different command line tools, many of which have options or forks to configure. When looking at the set of tools that needed to be migrated to modules, across all the editors, there were 63 separate tools.

All these tools need to understand the code, and they use the same standard libraries to do it. Those libraries are optimized for these kinds of tools, but even so processing that much code takes a lot of time time. Almost none of the tools are capable of returning results within 100ms.
As developers type in their editor, multiple of these features need to activate, which means they are not just paying the cost once, but many times. The overall effect is an editing experience that feels sluggish, and features that are either not enabled or sometimes produce results that appear so slowly they are no longer useful when they arrive. This is a problem that increases with the size of the code base, which means it is getting worse over time, and is especially bad for the kinds of large code bases companies are dealing with as they use Go for more major tasks.

## Requirements

### Complete feature set

For gopls to be considered a success it has to implement the full feature set discussed [below](#Features).
This is the set of features that users need in order to feel as productive as they were with the tooling it is replacing. It does not include every feature of previous implementations, there are some features that are almost never used that should be dropped (like guru's pointer analysis) and some other features that do not easily fit and will have to be worked around (replacing the save hook/linter).

### Equivalent or better experience

For all of those features, the user experience must match or exceed the current one available in all editors.
This is an easy statement to make, but a hard one to validate or measure. Many of the possible measures fail to capture the experience.

For instance, if an attempt was made to measure the latency of a jump to definition call, the results would be fairly consistent from the old godef tool. From the gopls implementation there may be a much larger range of latencies, with the best being orders of magnitude faster, and the worse slightly worse, because gopls attempts to do far more work, but manages to cache it across calls.

Or for a completion call, it might be slower but produce a better first match such that users accept it more often, resulting in an overall better experience.

For the most part this has to rely on user reports. If users are refusing to switch because the experience is not better, it is clearly not done, if they are switching but most people are complaining, there are probably enough areas that are better to make the switch compelling but other areas which are worse. If most people are switching and either staying silent or being positive, it is probably done. When writing tools, the user is all that matters.

### Solid community of contributors

The scope and scale of the problem gopls is trying to solve is untenable for the core Go team, it is going to require a strong community to make it all happen.

This implies the code must be easy to contribute to, and easy for many developers to work on in parallel. The functionality needs to be well decoupled, and have a thorough testing story.

### Latencies that fall within user tolerance

There has been a lot of research on acceptable latencies for user actions.
<!-- TODO: research links -->
The main result that affects gopls is that feedback in direct response to continuous user actions needs to be under 100ms to be imperceptible, and anything above 200ms aggravates the user.
This means in general the aim has to be <100ms for anything that happens as the developer types.
There will always be cases where gopls fails to meet this deadline, and there needs to be ways to make the user experience okay in those cases, but in general the point of this deadline is to inform the basic architecture design, any solution that cannot theoretically meet this goal in the long term is the wrong answer.

### Easy to configure

Developers are very particular, and have very differing desires in their coding experience. gopls is going to have to support a significant amount of flexibility, in order to meet those desires.
The default settings however with no configuration at all must be the one that is best experience for most users, and where possible the features must be flexible without configuration so that the client can easily make the choices about treatment without changing its communication with gopls.

## Difficulties

### Volume of data

<!-- TODO: project sizes -->
* Small:
* Medium:
* Large:
* Corporate mono-repo: Much much bigger

Parsing and type checking large amounts of code is quite expensive, and the converted forms use a lot of space. As gopls has to keep updating this information while the developer types, it needs to manage how it caches the converted forms very carefully to balance memory use vs speed.

### Cache invalidation

The basic unit of operation for the type checking is the package, but the basic unit of operation for an editor is the file.
gopls needs to be able to map files to packages efficiently, so that when files change it knows which packages need to be updated (along with any other packages that transitively depended on them).
This is made especially difficult by the fact that changing the content of a file can modify which packages it is considered part of (either by changing the package declaration or the build tags), a file can be in more than one package, and changes can be made to files without using the editor, in which case it will not notify us of the changes.

### Inappropriate core functionality

The base libraries for Go (things like [go/token], [go/ast] and [go/types]) are all designed for compiler-like applications.
They tend to worry more about throughput than memory use, they have structures that are intended to grow and then be thrown away at program exit, and they are not designed to keep going in the presence of errors in the source they are handling.
They also have no abilities to do incremental changes.

Making a long running service work well with those libraries is a very large challenge, but writing new libraries would be far more work, and cause a significant long term cost as both sets of libraries would have to be maintained. Right now it is more important to get a working tool into the hands of users. In the long term this decision may have to be revisited, new low level libraries may be the only way to keep pushing the capabilities forwards.

### Build system capabilities

gopls is supposed to be build system agnostic, but it must use the build system to discover how files map to packages. When it tries to do so, even when the functionality is the same, the costs (in time, CPU and memory) are very different, and can significantly impact the user experience. Designing how gopls interacts with the build system to try to minimize or hide these differences is hard.

### Build tags

The build tag system in Go is quite powerful, and has many use cases. Source files can exclude themselves using powerful boolean logic on the set of active tags.
It is however designed for specifying the set of active tags on the command line, and the libraries are all designed to cope with only one valid combination at a time. There is also no way to work out the set of valid combinations.

Type checking a file requires knowledge of all the other files in the same package, and that set of files is modified by the build tags. The set of exported identifiers of a package is also affected by which files are in the package, and thus its build tags.

This means that even for files or packages that have no build tag controls it is not possible to produce correct results without knowing the set of build tags to consider.
This makes it very hard to produce useful results when viewing a file.

### Features not supported by LSP

There are some things it would be good to be able to do that do not fit easily into the existing LSP protocol.
For instance, displaying control flow information, automatic struct tags, complex refactoring...

Each feature will have to be considered carefully, and either propose a change to LSP, or add a way to have gopls specific extensions to the protocol that are still easy to use in all the editor plugins.

To avoid these at the start, only core LSP features will be implemented, as they are sufficient to meet the baseline requirements anyway, but the potential features need to be kept in mind in the core architecture.

### Distribution

Making sure that users are using the right version of gopls is going to be a problem. Each editor plugin is probably going to install the tools in its own way, some will choose to install it system wide, some will keep their own copy.

Because it is a brand new tool, it will be changing rapidly. If users are not informed they are on an old version they will be experiencing problems that have already been fixed, which is worse for them, and then probably reporting them, which wastes time for the gopls team. There needs to be a mechanism for gopls to check if is up to date, and a recommended way to install an up to date version.

### Debugging user problems

gopls is essentially a very stateful long running server on the developer's machine. Its basic operation is affected by many things, from the users environment to the contents of the local build cache. The data it is operating on is often a confidential code base that cannot be shared.
All of these things make it hard for users to report a bug usefully, or create a minimal reproduction.

There needs to be easy ways for users to report what information they can, and ways to attempt to reproduce problems without their entire state. This is also needed to produce regression tests.

## Basic design decisions

There are some fundamental architecture decisions that affect much of the rest of the design of the tool, making fundamental trade offs that impact the user experience.

### Process lifetime: *managed by the editor*

Processing a large code base to fully type check and then analyze it within the latency requirements is not feasible, and is one of the primary problems with the existing solutions. This remains true even if the computed information was cached on disk, as running analyzers and type checkers ends up requiring the full AST of all files in the dependency graph.
It is theoretically possible to do better, but only with a major re-write of the existing parsing and type checking libraries, something that is not feasible at this time.

This implies that gopls should be a long running process, that is able to cache and pre-calculate results in memory so that when a request arrives it can produce the answer much faster.

It could run as a daemon on the user's machine, but there are a lot of issues with managing a daemon. It may well be the right choice in the long term, and it should be allowed for in the fundamental architecture design, but to start with it will instead have a process that lasts as long as the editor that starts it, and that can easily be restarted.

### Caching: *in memory*

Persistent disk caches are very expensive to maintain, and require solving a lot of extra problems.
Although building the information required is expensive compared to the latencies required of the requests, it is fairly minor compared to the startup times of an editor, so it is expected that rebuilding the information when gopls is restarted will be acceptable.

The advantage gained from this is that gopls becomes stateless across restarts which means if it has issues or gets its state confused, a simple restart will often fix the problem.
It also means that when users report problems, the entire state of the on disk cache is not needed to diagnose and reproduce the issue.

### Communication: *stdin/stdout JSON*

The LSP specification defines the JSON messages that are normally used, but it does not define how those message should be sent, and there are implementations of the LSP that do not use JSON (for instance, Protocol buffers are an option).

The constraints on gopls are that it must be easy to integrate into *every editor* on *all operating systems*, and that it should not have large external dependencies.

JSON is part of the Go standard library, and is also the native language of LSP, so it makes the most sense. By far the best supported communication mechanism is the standard input and output of a process, and the common client implementations all have ways of using [JSON rpc 2] in this mode.  There were no complete and low dependency implementations of this protocol in Go, but it is a fairly small protocol on top of the JSON library that can be implemented with a moderate effort, and would be a generally useful library to have anyway.

In the future it is expected to run in separated client server mode, so writing it in a way that could use sockets instead of stdin/stdout from the start was the best way to make sure it remained possible. It was also a huge debugging aid to be able to run the gopls server by hand and watch/debug it outside the editor.

### Running other tools: *no*

<!--- TODO: subprocess discuss --->

## Features

<!--TODO(rstambler): Generate a file that lists all of the supported features.-->

There is a set of features that gopls needs to expose to be a comprehensive IDE solution.
The following is the minimum set of features, along with their existing solutions and how they should map to the LSP.

### Introspection

Introspection features tell developers information about their code while they work. They do not make or suggest changes.

---
Diagnostics | Static analysis results of the code, including compilation and lint errors
----------- | ---
Requires    | Full go/analysis run, which needs full AST, type and SSA information
LSP         | [`textDocument/publishDiagnostics`]
Previous    | `go build`, `go vet`, `golint`, [errcheck], [staticcheck] <!-- TODO: and all the rest -->
|           | This is one of the most important IDE features, allowing fast turn around without having to run compilers and checkers in the shell. Often used to power problem lists, gutter markers and squiggle underlines in the IDE. <br/> There is some complicated design work to do in order to let users customize the set of checks being run, preferably without having to recompile the main LSP binary.

---
Hover    | Information about the code under the cursor.
-------- | ---
Requires | AST and type information for the file and all dependencies
LSP      | [`textDocument/hover`]
Previous | [godoc], [gogetdoc]
|        | Used when reading code to display information known to the compiler but not always obvious from the code. For instance it may return the types of identifiers, or the documentation.

---
Signature help | Function parameter information and documentation
-------------- | ---
Requires       | AST and type information for the file and all dependencies
LSP            | [`textDocument/signatureHelp`]
Previous       | [gogetdoc]
|              | As a function call is being typed into code, it is helpful to know the parameters of that call to enable the developer to call it correctly.

### Navigation

Navigation features are designed to make it easier for a developer to find their way round a code base.

---
Definition | Select an identifier, and jump to the code where that identifier was defined.
---------- | ---
Requires   | Full type information for file and all dependencies
LSP        | [`textDocument/declaration`]
|          | [`textDocument/definition`]
|          | [`textDocument/typeDefinition`]
Previous   | [godef] |
|          | Asking the editor to open the place where a symbol was defined is one of the most commonly used code navigation tools inside an IDE when available. It is especially valuable when exploring an unfamiliar code base.<br/>Due to a limitation of the compiler output, it is not possible to use the binary data for this task (specifically it does not know column information) and thus it must parse from source.

---
Implementation | Reports the types that implement an interface
-------------- | ---
Requires       | Full workspace type knowledge
LSP            | [`textDocument/implementation`]
Previous       | [impl]
|              | This feature is hard to scale up to large code bases, and is going to take thought to get right. It may be feasible to implemented a more limited form in the meantime.

---
Document symbols | Provides the set of top level symbols in the current file.
---------------- | ---
Requires         | AST of the current file only
LSP              | [`textDocument/documentSymbol`]
Previous         | [go-outline], [go-symbols]
|                | Used to drive things like outline mode.

---
References | Find all references to the symbol under the cursor.
---------- | ---
Requires   | AST and type information for the **reverse** transitive closure
LSP        | [`textDocument/references`]
Previous   | [guru]
|          | This requires knowledge of every package that could possible depend on any packages the current file is part of. In the past this has been implemented either by global knowledge, which does not scale, or by specifying a "scope" which confused users to the point where they just did not use the tools. gopls is probably going to need a more powerful solution in the long term, but to start with automatically limiting the scope may produce acceptable results. This would probably be the module if known, or some sensible parent directory otherwise.

---
Folding  | Report logical hierarchies of blocks
-------- | ---
Requires | AST of the current file only
LSP      | [`textDocument/foldingRange`]
Previous | [go-outline]
|        | This is normally used to provide expand and collapse behavior in editors.

---
Selection | Report regions of logical selection around the cursor
--------- | ---
Requires  | AST of the current file only
LSP       | [`textDocument/selectionRange`]
Previous  | [guru]
|         | Used in editor features like expand selection.


### Edit assistance

These features suggest or apply edits to the code for the user, including refactoring features, for which there are many potential use cases.
Refactoring is one of the places where Go tools could potentially be very strong, but have not been so far, and thus there is huge potential for improvements in the developer experience.
There is not yet a clear understanding of the kinds of refactoring people need or how they should express them however, and there are weaknesses in the LSP protocol around this.
This means it may be much more of a research project.


---
Format   | Fix the formatting of the file
-------- | ---
Requires | AST of current file
LSP      | [`textDocument/formatting`]
|        | [`textDocument/rangeFormatting`]
|        | [`textDocument/onTypeFormatting`]
Previous | [gofmt], [goimports], [goreturns]
|        | It will use the standard format package. <br/> Current limitations are that it does not work on malformed code. It may need some very careful changes to the formatter to allow for formatting an invalid AST or changes to force the AST to a valid mode. These changes would improve range and file mode as well, but are basically vital to onTypeFormatting

---
Imports  | Rewrite the imports block automatically to match the symbols used.
-------- | ---
Requires | AST of the current file and full symbol knowledge for all candidate packages.
LSP      | [`textDocument/codeAction`]
Previous | [goimports], [goreturns]
|        | This needs knowledge of packages that are not yet in use, and the ability to find those packages by name. <br/> It also needs exported symbol information for all the packages it discovers. <br/> It should be implemented using the standard imports package, but there may need to be exposed a more fine grained API than just a file rewrite for some of the interactions.

---
Autocompletion | Makes suggestions to complete the entity currently being typed.
-------------- | ---
Requires       | AST and type information for the file and all dependencies<br/> Also full exported symbol knowledge for all packages.
LSP            | [`textDocument/completion`]
|              | [`completionItem/resolve`]
Previous       | [gocode]
|              | Autocomplete is one of the most complicated features, and the more it knows the better its suggestions can be. For instance it can autocomplete into packages that are not yet being imported if it has their public symbols. It can make better suggestions of options if it knows what kind of program you are writing. It can suggest better arguments if it knows how you normally call a function. It can suggest entire patterns of code if it knows they are common. Unlike many other features, which have a specific task, and once it is doing that task the feature is done, autocomplete will never be finished. Balancing and improving both the candidates and how they are ranked will be a research problem for a long time to come.

---
Rename   | Rename an identifier
-------- | ---
Requires | AST and type information for the **reverse** transitive closure
LSP      | [`textDocument/rename`]
|        | [`textDocument/prepareRename`]
Previous | golang.org/x/tools/cmd/gorename
|        | This uses the same information that find references does, with all the same problems and limitations. It is slightly worse because the changes it suggests make it intolerant of incorrect results. It is also dangerous using it to change the public API of a package.

---
Suggested fixes | Suggestions that can be manually or automatically accepted to change the code
--------------- | ---
Requires        | Full go/analysis run, which needs full AST, type and SSA information
LSP             | [`textDocument/codeAction`]
Previous        | N/A
|               | This is a brand new feature powered by the new go/analysis engine, and it should allow a huge amount of automated refactoring.

[LSP specification]: https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/
[talk]: https://www.youtube.com/watch?v=EFJfdWzBHwE
[slides]: https://github.com/gophercon/2019-talks/blob/master/RebeccaStambler-GoPleaseStopBreakingMyEditor/slides.pdf "Go, please stop breaking my editor!"
[JSON rpc 2]: https://www.jsonrpc.org/specification

[errcheck]: https://github.com/kisielk/errcheck
[go-outline]: https://github.com/lukehoban/go-outline
[go-symbols]: https://github.com/acroca/go-symbols
[gocode]: https://github.com/stamblerre/gocode
[godef]: https://github.com/rogpeppe/godef
[godoc]: https://golang.org/cmd/godoc
[gofmt]: https://golang.org/cmd/gofmt
[gogetdoc]: https://github.com/zmb3/gogetdoc
[goimports]: https://pkg.go.dev/golang.org/x/tools/cmd/goimports
[goreturns]: https://github.com/sqs/goreturns
[gotags]: https://github.com/jstemmer/gotags
[guru]: https://pkg.go.dev/golang.org/x/tools/cmd/guru
[impl]: https://github.com/josharian/impl
[staticcheck]: https://staticcheck.io/docs/
[go/types]: https://golang.org/pkg/go/types/
[go/ast]: https://golang.org/pkg/go/ast/
[go/token]: https://golang.org/pkg/go/token/

[`completionItem/resolve`]:https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#completionItem_resolve
[`textDocument/codeAction`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_codeAction
[`textDocument/completion`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_completion
[`textDocument/declaration`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_declaration
[`textDocument/definition`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_definition
[`textDocument/documentLink`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_documentLink
[`textDocument/documentSymbol`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_documentSymbol
[`textDocument/foldingRange`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_foldingRange
[`textDocument/formatting`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_formatting
[`textDocument/highlight`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_highlight
[`textDocument/hover`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_hover
[`textDocument/implementation`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_implementation
[`textDocument/onTypeFormatting`]:https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_onTypeFormatting
[`textDocument/prepareRename`]:https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_prepareRename
[`textDocument/publishDiagnostics`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_publishDiagnostics
[`textDocument/rangeFormatting`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_rangeFormatting
[`textDocument/references`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_references
[`textDocument/rename`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_rename
[`textDocument/selectionRange`]:https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_selectionRange
[`textDocument/signatureHelp`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_signatureHelp
[`textDocument/typeDefinition`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_typeDefinition
[`workspace/didChangeWatchedFiles`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#workspace_didChangeWatchedFiles


================================================
FILE: gopls/doc/design/implementation.md
================================================
---
title: "Gopls: Implementation"
---

Last major update: Jan 16 2024

This doc presents a high-level overview of the structure of gopls to
help new contributors find their way. It is not intended to be a
complete description of the implementation, nor even of any key
components; for that, the package documentation (linked below) and
other comments within the code are a better guide.

The diagram below shows selected components of the gopls module and
their relationship to each other according to the Go import graph.
Tests and test infrastructure are not shown, nor are utility packages,
nor packages from the [x/tools] module. For brevity, packages are
referred to by their last segment, which is usually unambiguous.

The height of each blob corresponds loosely to its technical depth.
Some blocks are wide and shallow, such as [protocol], which declares
Go types for the entire LSP protocol. Others are deep, such as [cache]
and [golang], as they contain a lot of dense logic and algorithms.

<!-- Source: https://docs.google.com/drawings/d/1CK6YSLt7G3svRoZf7skJI-lxRol2VI90YOxHcYS0DP4 -->
![Gopls architecture](architecture.svg)

Starting from the bottom, we'll describe the various components.

The lowest layer defines the request and response types of the
Language Server Protocol:

- The [protocol] package defines the standard protocol; it is mostly
  generated mechanically from the schema definition provided by
  Microsoft.
  The most important type is DocumentURI, which represents a `file:`
  URL that identifies a client editor document. It also provides
  `Mapper`, which maps between the different coordinate systems used
  for source positions: UTF-8, UTF-16, and token.Pos.

- The [command] package defines Gopls's non-standard commands, which
  are all invoked through the `workspace/executeCommand` extension
  mechanism. These commands are typically returned by the server as
  continuations of Code Actions or Code Lenses; most clients do not
  construct calls to them directly.

The next layer defines a number of important and very widely used data structures:

- The [file] package defines the primary abstractions of a client
  file: its `Identity` (URI and content hash), and its `Handle` (which
  additionally provides the version and content of a particular
  snapshot of the file.

- The [parsego] package defines `File`, the parsed form of a Go source
  file, including its content, syntax tree, and coordinary mappings
  (Mapper and token.File). The package performs various kinds of tree
  repair to work around error-recovery shortcomings of the Go parser.

- The [metadata] package defines `Package`, an abstraction of the
  metadata of a Go package, similar to the output of `go list -json`.
  Metadata is produced from [go/packages], which takes
  care of invoking `go list`. (Users report that it works to some extent
  with a GOPACKAGESDRIVER for Bazel, though we maintain no tests for this
  scenario.)

  The package also provides `Graph`, the complete import graph for a
  workspace; each graph node is a `Package`.

The [settings] layer defines the data structure (effectively a large
tree) for gopls configuration options, along with its JSON encoding.

The [cache] layer is the largest and most complex component of gopls.
It is concerned with state management, dependency analysis, and invalidation:
the `Session` of communication with the client;
the `Folder`s that the client has opened;
the `View` of a particular workspace tree with particular build
options;
the `Snapshot` of the state of all files in the workspace after a
particular edit operation;
the contents of all files, whether saved to disk (`DiskFile`) or
edited and unsaved (`Overlay`);
the `Cache` of in-memory memoized computations,
such as parsing go.mod files or build the symbol index;
and the `Package`, which holds the results of type checking a package
from Go syntax.

The cache layer depends on various auxiliary packages, including:

- The [filecache] package, which manages gopls' persistent, transactional,
  file-based key/value store.
  
- The [xrefs], [methodsets], and [typerefs] packages define algorithms
  for constructing indexes of information derived from type-checking,
  and for encoding and decoding these serializable indexes in the file
  cache.

  Together these packages enable the fast restart, reduced memory
  consumption, and synergy across processes that were delivered by the
  v0.12 redesign and described in ["Scaling gopls for the growing Go
  ecosystem"](https://go.dev/blog/gopls-scalability).

The cache also defines gopls's [go/analysis] driver, which runs
modular analysis (similar to `go vet`) across the workspace.
Gopls also includes a number of analysis passes that are not part of vet.

The next layer defines four packages, each for handling files in a
particular language:
[mod] for go.mod files;
[work] for go.work files;
[template] for files in `text/template` syntax; and
[golang], for files in Go itself.
This package, by far the largest, provides the main features of gopls:
navigation, analysis, and refactoring of Go code.
As most users imagine it, this package _is_ gopls.

The [server] package defines the LSP service implementation, with one
handler method per LSP request type. Each handler switches on the type
of the file and dispatches to one of the four language-specific
packages.

The [lsprpc] package connects the service interface to our [jsonrpc2](https://www.jsonrpc.org/specification) server.

Bear in mind that the diagram is a dependency graph, a "static"
viewpoint of the program's structure. A more dynamic viewpoint would
order the packages based on the sequence in which they are encountered
during processing of a particular request; in such a view, the bottom
layer would represent the "wire" (protocol and command), the next
layer up would hold the RPC-related packages (lsprpc and server), and
features (e.g. golang, mod, work, template) would be at the top.

<!--
A dynamic view would be an interesting topic for another article.
This slide deck [requires Google network]
The Life of a (gopls) Query (Oct 2021)
https://docs.google.com/presentation/d/1c8XJaIldzii-F3YvEOPWHK_MQJ_o8ua5Bct1yDa3ZlU
provides useful (if somewhat out of date) information.
-->

The [cmd] package defines the command-line interface of the `gopls`
command, around which gopls's main package is just a trivial wrapper.
It is usually run without arguments, causing it to start a server and
listen indefinitely.
It also provides a number of subcommands that start a server, make a
single request to it, and exit, providing traditional batch-command
access to server functionality. These subcommands are primarily
provided as a debugging aid; but see https://go.dev/issue/63693.

[cache]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache
[cmd]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cmd
[command]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/protocol/command
[debug]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/debug
[file]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/file
[filecache]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/filecache
[go/analysis]: https://pkg.go.dev/golang.org/x/tools@master/go/analysis
[go/packages]: https://pkg.go.dev/golang.org/x/tools@master/go/packages
[gopls]: https://pkg.go.dev/golang.org/x/tools/gopls@master
[jsonrpc]: https://pkg.go.dev/golang.org/x/tools@master/internal/jsonrpc
[jsonrpc2]: https://pkg.go.dev/golang.org/x/tools@master/internal/jsonrpc2
[lsprpc]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/lsprpc
[memoize]: https://github.com/golang/tools/tree/master/internal/memoize
[metadata]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache/metadata
[methodsets]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache/methodsets
[mod]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/mod
[parsego]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache/parsego
[protocol]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/protocol
[server]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/server
[settings]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/settings
[golang]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/golang
[template]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/template
[typerefs]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache/typerefs
[work]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/work
[x/tools]: https://github.com/golang/tools@master
[xrefs]: https://pkg.go.dev/golang.org/x/tools/gopls@master/internal/cache/xrefs


================================================
FILE: gopls/doc/design/integrating.md
================================================
---
title: "Documentation for plugin authors"
---

If you are integrating `gopls` into an editor by writing an editor plugin, there are quite a few semantics of the communication between the editor and `gopls` that are not specified by the [LSP specification].

We attempt to document those details along with any other information that has been helpful to other plugin authors here.

If you are implementing a plugin yourself and have questions this page does not answer, please reach out to us to ask, and then also contribute your findings back to this page.

## Supported features

For the most part you should look at the [Index of features](../features/)
to know whether gopls supports a feature.

For a truly authoritative answer you should check the [result][InitializeResult] of the [initialize] request, where gopls enumerates its support in the [ServerCapabilities].


## Positions and ranges

Many LSP requests pass position or range information. This is described in the [LSP specification][lsp-text-documents]:

> A position inside a document (see Position definition below) is expressed as a zero-based line and character offset. The offsets are based on a UTF-16 string representation. So a string of the form a𐐀b the character offset of the character a is 0, the character offset of 𐐀 is 1 and the character offset of b is 3 since 𐐀 is represented using two code units in UTF-16.

This means that integrators will need to calculate UTF-16 based column offsets.
Use `protocol.Mapper` for all the conversions.

## Edits

In order to deliver changes from gopls to the editor, the LSP supports arrays of [`TextEdit`][lsp-textedit]s in responses.
The spec specifies exactly how these should be applied:

> All text edits ranges refer to positions in the original document. Text edits ranges must never overlap, that means no part of the original document must be manipulated by more than one edit. However, it is possible that multiple edits have the same start position: multiple inserts, or any number of inserts followed by a single remove or replace edit. If multiple inserts have the same position, the order in the array defines the order in which the inserted strings appear in the resulting text.

All `[]TextEdit` are sorted such that applying the array of deltas received in reverse order achieves the desired result that holds with the spec.

## Errors

Various error codes are described in the [LSP specification][lsp-response]. We are still determining what it means for a method to return an error; are errors only for low-level LSP/transport issues or can other conditions cause errors to be returned? See some of this discussion on [#31526].

The method chosen is currently influenced by the exact treatment in the currently popular editor integrations. It may well change, and ideally would become more coherent across requests.

* [`textDocument/codeAction`]: Return error if there was an error computing code actions.
* [`textDocument/completion`]: Log errors, return empty result list.
* [`textDocument/definition`]: Return error if there was an error computing the definition for the position.
* [`textDocument/typeDefinition`]: Return error if there was an error computing the type definition for the position.
* [`textDocument/formatting`]: Return error if there was an error formatting the file.
* [`textDocument/highlight`]: Log errors, return empty result.
* [`textDocument/hover`]: Return empty result.
* [`textDocument/documentLink`]: Log errors, return nil result.
* [`textDocument/publishDiagnostics`]: Log errors if there were any while computing diagnostics.
* [`textDocument/references`]: Log errors, return empty result.
* [`textDocument/rename`]: Return error if there was an error computing renames.
* [`textDocument/signatureHelp`]: Log errors, return nil result.
* [`textDocument/documentSymbols`]: Return error if there was an error computing document symbols.

## Watching files

It is fairly normal for files that affect `gopls` to be modified outside of the editor it is associated with.

For instance, files that are needed to do correct type checking are modified by switching branches in git, or updated by a code generator.

Monitoring files inside gopls directly has a lot of awkward problems, but the [LSP specification] has methods that allow gopls to request that the client notify it of file system changes, specifically [`workspace/didChangeWatchedFiles`].
This is currently being added to gopls by a community member, and tracked in [#31553]

[InitializeResult]: https://pkg.go.dev/golang.org/x/tools/gopls/internal/protocol#InitializeResult
[ServerCapabilities]: https://pkg.go.dev/golang.org/x/tools/gopls/internal/protocol#ServerCapabilities
[`golang.org/x/tools/gopls/internal/protocol`]: https://pkg.go.dev/golang.org/x/tools/internal/protocol#NewPoint

[LSP specification]: https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/
[lsp-response]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#response-message
[initialize]: https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#initialize
[lsp-text-documents]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#text-documents
[lsp-textedit]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textedit

[`textDocument/codeAction`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_codeAction
[`textDocument/completion`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_completion
[`textDocument/definition`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_definition
[`textDocument/typeDefinition`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_typeDefinition
[`textDocument/formatting`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_formatting
[`textDocument/highlight`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_highlight
[`textDocument/hover`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_hover
[`textDocument/documentLink`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_documentLink
[`textDocument/publishDiagnostics`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_publishDiagnostics
[`textDocument/references`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_references
[`textDocument/rename`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_rename
[`textDocument/signatureHelp`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_signatureHelp
[`textDocument/documentSymbols`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#textDocument_documentSymbols
[`workspace/didChangeWatchedFiles`]: https://github.com/Microsoft/language-server-protocol/blob/gh-pages/_specifications/specification-3-14.md#workspace_didChangeWatchedFiles

[#31080]: https://github.com/golang/go/issues/31080
[#31553]: https://github.com/golang/go/issues/31553
[#31526]: https://github.com/golang/go/issues/31526


================================================
FILE: gopls/doc/editor/emacs.md
================================================
---
title: "Gopls: Using Emacs"
---

## Installing `gopls`

To use `gopls` with Emacs, you must first
[install the `gopls` executable](../index.md#installation) and ensure that the directory
containing the resulting binary (either `$(go env GOBIN)` or `$(go env
GOPATH)/bin`) is in your `PATH`.

## Choosing an Emacs LSP client

To use `gopls` with Emacs, you will need to choose and install an Emacs LSP
client package. Two popular client packages are [LSP Mode] and [Eglot].

LSP Mode takes a batteries-included approach, with many integrations enabled
“out of the box” and several additional behaviors provided by `lsp-mode` itself.

Eglot takes a minimally-intrusive approach, focusing on smooth integration with
other established packages. It provides a few of its own `eglot-` commands but
no additional keybindings by default.

Once you have selected which client you want to use, install it per the packages
instructions: see [Eglot 1-2-3](https://github.com/joaotavora/eglot#1-2-3) or
[LSP Mode Installation](https://emacs-lsp.github.io/lsp-mode/page/installation/).

## Common configuration

Both Eglot and LSP Mode can integrate with popular packages in the Emacs
ecosystem:

* The built-in [`xref`] package provides cross-references.
* The built-in [Flymake] package provides an on-the-fly diagnostic overlay.
* [Company] mode displays code completion candidates (with a richer UI than
  the built-in [`completion-at-point`]).

Eglot provides documentation using the built-in [ElDoc] minor mode, while LSP
Mode by default provides documentation using its own [`lsp-ui`] mode.

Eglot by default locates the project root using the [`project`] package. In LSP
Mode, this behavior can be configured using the `lsp-auto-guess-root` setting.

## Configuring LSP Mode

### Loading LSP Mode in `.emacs`

```elisp
(require 'lsp-mode)
(add-hook 'go-mode-hook #'lsp-deferred)

;; Set up before-save hooks to format buffer and add/delete imports.
;; Make sure you don't have other gofmt/goimports hooks enabled.
(defun lsp-go-install-save-hooks ()
  (add-hook 'before-save-hook #'lsp-format-buffer t t)
  (add-hook 'before-save-hook #'lsp-organize-imports t t))
(add-hook 'go-mode-hook #'lsp-go-install-save-hooks)
```

### Configuring `gopls` via LSP Mode

See [settings](../settings) for information about available gopls settings.

Stable gopls settings have corresponding configuration variables in `lsp-mode`.
For example, `(setq lsp-gopls-use-placeholders nil)` will disable placeholders
in completion snippets. See [`lsp-go`] for a list of available variables.

Experimental settings can be configured via `lsp-register-custom-settings`:

```lisp
(lsp-register-custom-settings
 '(("gopls.completeUnimported" t t)
   ("gopls.staticcheck" t t)))
```

Note that after changing settings you must restart gopls using e.g. `M-x
lsp-restart-workspace`.

## Configuring Eglot

### Configuring `project` for Go modules in `.emacs`

Eglot uses the built-in `project` package to identify the LSP workspace for a
newly-opened buffer. The `project` package does not natively know about `GOPATH`
or Go modules. Fortunately, you can give it a custom hook to tell it to look for
the nearest parent `go.mod` file (that is, the root of the Go module) as the
project root.

```elisp
(require 'project)

(defun project-find-go-module (dir)
  (when-let ((root (locate-dominating-file dir "go.mod")))
    (cons 'go-module root)))

(cl-defmethod project-root ((project (head go-module)))
  (cdr project))

(add-hook 'project-find-functions #'project-find-go-module)
```

### Loading Eglot in `.emacs`

```elisp
;; Optional: load other packages before eglot to enable eglot integrations.
(require 'company)
(require 'yasnippet)

(require 'go-mode)
(require 'eglot)
(add-hook 'go-mode-hook 'eglot-ensure)

;; Optional: install eglot-format-buffer as a save hook.
;; The depth of -10 places this before eglot's willSave notification,
;; so that notification reports the actual contents that will be saved.
(defun eglot-format-buffer-before-save ()
  (add-hook 'before-save-hook #'eglot-format-buffer -10 t))
(add-hook 'go-mode-hook #'eglot-format-buffer-before-save)
```

Use `M-x eglot-upgrade-eglot` to upgrade to the latest version of
Eglot.

### Configuring `gopls` via Eglot

See [settings](../settings) for information about available gopls settings.

LSP server settings are controlled by the `eglot-workspace-configuration`
variable, which can be set either globally in `.emacs` or in a `.dir-locals.el` file in the project root.

`.emacs`:
```elisp
(setq-default eglot-workspace-configuration
    '((:gopls .
        ((staticcheck . t)
         (matcher . "CaseSensitive")))))
```

`.dir-locals.el`:
```elisp
((nil (eglot-workspace-configuration . ((gopls . ((staticcheck . t)
						  (matcher . "CaseSensitive")))))))
```

### Organizing imports with Eglot

`gopls` provides the import-organizing functionality of `goimports` as an LSP
code action, which you can invoke as needed by running `M-x eglot-code-actions`
(or a key of your choice bound to the `eglot-code-actions` function) and
selecting `Organize Imports` at the prompt.

To automatically organize imports before saving, add a hook:

```elisp
(add-hook 'before-save-hook
    (lambda ()
        (call-interactively 'eglot-code-action-organize-imports))
    nil t)
```

## Troubleshooting

Common errors:

* When prompted by Emacs for your project folder, if you are using modules you
  must select the module's root folder (i.e. the directory with the "go.mod").
  If you are using GOPATH, select your $GOPATH as your folder.
* Emacs must have your environment set properly (PATH, GOPATH, etc). You can
  run `M-x getenv <RET> PATH <RET>` to see if your PATH is set in Emacs. If
  not, you can try starting Emacs from your terminal, using [this
  package][exec-path-from-shell], or moving your shell config from `.bashrc`
  into `.profile` and logging out and back in.
* Make sure only one LSP client mode is installed. (For example, if using
  `lsp-mode`, ensure that you are not _also_ enabling `eglot`.)
* Look for errors in the `*lsp-log*` buffer or run `M-x eglot-events-buffer`.
* Ask for help in the `#emacs` channel on the [Gophers slack].

[LSP Mode]: https://emacs-lsp.github.io/lsp-mode/
[Eglot]: https://github.com/joaotavora/eglot/blob/master/README.md
[`xref`]: https://www.gnu.org/software/emacs/manual/html_node/emacs/Xref.html
[Flymake]: https://www.gnu.org/software/emacs/manual/html_node/flymake/Using-Flymake.html#Using-Flymake
[Company]: https://company-mode.github.io/
[`completion-at-point`]: https://www.gnu.org/software/emacs/manual/html_node/elisp/Completion-in-Buffers.html
[ElDoc]: https://elpa.gnu.org/packages/eldoc.html
[`lsp-ui`]: https://emacs-lsp.github.io/lsp-ui/
[`lsp-go`]: https://github.com/emacs-lsp/lsp-mode/blob/master/clients/lsp-go.el
[`use-package`]: https://github.com/jwiegley/use-package
[`exec-path-from-shell`]: https://github.com/purcell/exec-path-from-shell
[settings]: settings.md
[Gophers slack]: https://invite.slack.golangbridge.org/


================================================
FILE: gopls/doc/editor/helix.md
================================================
---
title: "Gopls: Using Helix"
---

Configuring `gopls` to work with Helix is rather straightforward. Install `gopls`, and then add it to the `PATH` variable. If it is in the `PATH` variable, Helix will be able to detect it automatically.

The documentation explaining how to install the default language servers for Helix can be found [here](https://github.com/helix-editor/helix/wiki/How-to-install-the-default-language-servers)

## Installing `gopls`

The first step is to install `gopls` on your machine.
You can follow installation instructions [here](https://github.com/golang/tools/tree/master/gopls#installation).

## Setting your path to include `gopls`

Set your `PATH` environment variable to point to `gopls`.
If you used `go install` to download `gopls`, it should be in `$GOPATH/bin`.
If you don't have `GOPATH` set, you can use `go env GOPATH` to find it.

## Additional information

You can find more information about how to set up the LSP formatter [here](https://github.com/helix-editor/helix/wiki/How-to-install-the-default-language-servers#autoformatting).

It is possible to use `hx --health go` to see that the language server is properly set up.

### Configuration

The settings for `gopls` can be configured in the `languages.toml` file.
The official Helix documentation for this can be found [here](https://docs.helix-editor.com/languages.html)

Configuration pertaining to `gopls` should be in the table `language-server.gopls`.

#### How to set flags

To set flags, add them to the `args` array in the `language-server.gopls` section of the `languages.toml` file.

#### How to set LSP configuration

Configuration options can be set in the `language-server.gopls.config` section of the `languages.toml` file, or in the `config` key of the `language-server.gopls` section of the `languages.toml` file.

#### A minimal config example

In the `~/.config/helix/languages.toml` file, the following snippet would set up `gopls` with a logfile located at `/tmp/gopls.log` and enable staticcheck.

```toml
[language-server.gopls]
command = "gopls"
args = ["-logfile=/tmp/gopls.log",  "serve"]
[language-server.gopls.config]
"ui.diagnostic.staticcheck" = true
```




================================================
FILE: gopls/doc/editor/sublime.md
================================================
---
title: "Gopls: Using Sublime Text"
---

Use the [LSP] package. After installing it using Package Control, do the following:

* Open the **Command Palette**
* Find and run the command **LSP: Enable Language Server Globally**
* Select the **gopls** item. Be careful not to select the similarly named *golsp* by mistake.

Finally, you should familiarise yourself with the LSP package's *Settings* and *Key Bindings*. Find them under the menu item **Preferences > Package Settings > LSP**.

## Examples
Minimal global LSP settings, that assume **gopls** and **go** appear on the PATH seen by Sublime Text:<br>
```
{
    "clients": {
        "gopls": {
             "enabled": true,
         }
    }
}
```

Global LSP settings that supply a specific PATH for finding **gopls** and **go**, as well as some settings for Sublime LSP itself:
```
{
    "clients": {
        "gopls": {
            "enabled": true,
            "env": {
                "PATH": "/path/to/your/go/bin",
            }
        }
    },
    // Recommended by https://agniva.me/gopls/2021/01/02/setting-up-gopls-sublime.html
    // except log_stderr mentioned there is no longer recognized.
    "show_references_in_quick_panel": true,
    "log_debug": true,
    // These two are recommended by LSP-json as replacement for deprecated only_show_lsp_completions
    "inhibit_snippet_completions": true,
    "inhibit_word_completions": true,
 }
 ```

LSP and gopls settings can also be adjusted on a per-project basis to override global settings.
```
{
    "folders": [
        {
            "path": "/path/to/a/folder/one"
        },
        {
            // If you happen to be working on Go itself, this can be helpful; go-dev/bin should be on PATH.
            "path": "/path/to/your/go-dev/src/cmd"
        }
     ],
    "settings": {
        "LSP": {
            "gopls": {
                // To use a specific version of gopls with Sublime Text LSP (e.g., to try new features in development)
                "command": [
                    "/path/to/your/go/bin/gopls"
                ],
                "env": {
                    "PATH": "/path/to/your/go-dev/bin:/path/to/your/go/bin",
                    "GOPATH": "",
                },
                "settings": {
                    "experimentalWorkspaceModule": true
                }
            }
        },
        // This will apply for all languages in this project that have
        // LSP servers, not just Go, however cannot enable just for Go.
        "lsp_format_on_save": true,
    }
}
```

Usually changes to these settings are recognized after saving the project file, but it may sometimes be necessary to either restart the server(s) (**Tools > LSP > Restart Servers**) or quit and restart Sublime Text itself.

[LSP]: https://packagecontrol.io/packages/LSP


================================================
FILE: gopls/doc/editor/vim.md
================================================
---
title: "Gopls: Using Vim or Neovim"
---

* [vim-go](#vimgo)
* [LanguageClient-neovim](#lcneovim)
* [Ale](#ale)
* [vim-lsp](#vimlsp)
* [vim-lsc](#vimlsc)
* [coc.nvim](#cocnvim)
* [govim](#govim)
* [Neovim v0.5.0+](#neovim)
  * [Installation](#neovim-install)
  * [Custom Configuration](#neovim-config)
  * [Imports](#neovim-imports)
  * [Omnifunc](#neovim-omnifunc)
  * [Additional Links](#neovim-links)

## <a href="#vimgo" id="vimgo">vim-go</a>

Use [vim-go] ver 1.20+, with the following configuration:

```vim
let g:go_def_mode='gopls'
let g:go_info_mode='gopls'
```

## <a href="#lcneovim" id="lcneovim">LanguageClient-neovim</a>

Use [LanguageClient-neovim], with the following configuration:

```vim
" Launch gopls when Go files are in use
let g:LanguageClient_serverCommands = {
       \ 'go': ['gopls']
       \ }
" Run gofmt on save
autocmd BufWritePre *.go :call LanguageClient#textDocument_formatting_sync()
```

## <a href="#ale" id="ale">Ale</a>

Use [ale]:

```vim
let g:ale_linters = {
  \ 'go': ['gopls'],
  \}
```

see [this issue][ale-issue-2179]

## <a href="#vimlsp" id="vimlsp">vim-lsp</a>

Use [prabirshrestha/vim-lsp], with the following configuration:

```vim
augroup LspGo
  au!
  autocmd User lsp_setup call lsp#register_server({
      \ 'name': 'gopls',
      \ 'cmd': {server_info->['gopls']},
      \ 'whitelist': ['go'],
      \ })
  autocmd FileType go setlocal omnifunc=lsp#complete
  "autocmd FileType go nmap <buffer> gd <plug>(lsp-definition)
  "autocmd FileType go nmap <buffer> ,n <plug>(lsp-next-error)
  "autocmd FileType go nmap <buffer> ,p <plug>(lsp-previous-error)
augroup END
```

## <a href="#vimlsc" id="vimlsc">vim-lsc</a>

Use [natebosch/vim-lsc], with the following configuration:

```vim
let g:lsc_server_commands = {
\  "go": {
\    "command": "gopls serve",
\    "log_level": -1,
\    "suppress_stderr": v:true,
\  },
\}
```

The `log_level` and `suppress_stderr` parts are needed to prevent breakage from logging. See
issues [#180](https://github.com/natebosch/vim-lsc/issues/180) and
[#213](https://github.com/natebosch/vim-lsc/issues/213).

## <a href="#cocnvim" id="cocnvim">coc.nvim</a>

Use [coc.nvim], with the following `coc-settings.json` configuration:

```json
  "languageserver": {
    "go": {
      "command": "gopls",
      "rootPatterns": ["go.work", "go.mod", ".vim/", ".git/", ".hg/"],
      "filetypes": ["go"],
      "initializationOptions": {
        "usePlaceholders": true
      }
    }
  }
```

If you use `go.work` files, you may want to set the
`workspace.workspaceFolderCheckCwd` option. This will force coc.nvim to search
parent directories for `go.work` files, even if the current open directory has
a `go.mod` file. See the
[coc.nvim documentation](https://github.com/neoclide/coc.nvim/wiki/Using-workspaceFolders)
for more details.

Other [settings](../settings) can be added in `initializationOptions` too.

The `editor.action.organizeImport` code action will auto-format code and add missing imports. To run this automatically on save, add the following line to your `init.vim`:

```vim
autocmd BufWritePre *.go :call CocAction('runCommand', 'editor.action.organizeImport')
```

## <a href="#govim" id="govim">govim</a>

In vim classic only, use the experimental [`govim`], simply follow the [install steps][govim-install].

## <a href="#neovim" id="neovim">Neovim v0.5.0+</a>

To use the new native LSP client in Neovim, make sure you
[install][nvim-install] Neovim v.0.5.0+,
the `nvim-lspconfig` configuration helper plugin, and check the
[`gopls` configuration section][nvim-lspconfig] there.

### <a href="#neovim-install" id="neovim-install">Installation</a>

You can use Neovim's native plugin system.  On a Unix system, you can do that by
cloning the `nvim-lspconfig` repository into the correct directory:

```sh
dir="${HOME}/.local/share/nvim/site/pack/nvim-lspconfig/opt/nvim-lspconfig/"
mkdir -p "$dir"
cd "$dir"
git clone 'https://github.com/neovim/nvim-lspconfig.git' .
```

### <a href="#neovim-config" id="neovim-config">Configuration</a>

nvim-lspconfig aims to provide reasonable defaults, so your setup can be very
brief.

```lua
local lspconfig = require("lspconfig")
lspconfig.gopls.setup({})
```

However, you can also configure `gopls` for your preferences. Here's an
example that enables `unusedparams`, `staticcheck`, and `gofumpt`.

```lua
local lspconfig = require("lspconfig")
lspconfig.gopls.setup({
  settings = {
    gopls = {
      analyses = {
        unusedparams = true,
      },
      staticcheck = true,
      gofumpt = true,
    },
  },
})
```

### <a href="#neovim-imports" id="neovim-imports">Imports and Formatting</a>

Use the following configuration to have your imports organized on save using
the logic of `goimports` and your code formatted.

```lua
autocmd("BufWritePre", {
  pattern = "*.go",
  callback = function()
    local params = vim.lsp.util.make_range_params()
    params.context = {only = {"source.organizeImports"}}
    -- buf_request_sync defaults to a 1000ms timeout. Depending on your
    -- machine and codebase, you may want longer. Add an additional
    -- argument after params if you find that you have to write the file
    -- twice for changes to be saved.
    -- E.g., vim.lsp.buf_request_sync(0, "textDocument/codeAction", params, 3000)
    local result = vim.lsp.buf_request_sync(0, "textDocument/codeAction", params)
    for cid, res in pairs(result or {}) do
      for _, r in pairs(res.result or {}) do
        if r.edit then
          local enc = (vim.lsp.get_client_by_id(cid) or {}).offset_encoding or "utf-16"
          vim.lsp.util.apply_workspace_edit(r.edit, enc)
        end
      end
    end
    vim.lsp.buf.format({async = false})
  end
})
```

### <a href="#neovim-omnifunc" id="neovim-omnifunc">Omnifunc</a>

In Neovim v0.8.1 and later if you don't set the option `omnifunc`, it will auto
set to `v:lua.vim.lsp.omnifunc`. If you are using an earlier version, you can
configure it manually:

```lua
local on_attach = function(client, bufnr)
  -- Enable completion triggered by <c-x><c-o>
  vim.api.nvim_buf_set_option(bufnr, 'omnifunc', 'v:lua.vim.lsp.omnifunc')
end
require('lspconfig').gopls.setup({
   on_attach = on_attach
})
```

### <a href="#neovim-links" id="neovim-links">Additional Links</a>

* [Neovim's official LSP documentation][nvim-docs].

[vim-go]: https://github.com/fatih/vim-go
[LanguageClient-neovim]: https://github.com/autozimu/LanguageClient-neovim
[ale]: https://github.com/w0rp/ale
[ale-issue-2179]: https://github.com/w0rp/ale/issues/2179
[prabirshrestha/vim-lsp]: https://github.com/prabirshrestha/vim-lsp/
[natebosch/vim-lsc]: https://github.com/natebosch/vim-lsc/
[natebosch/vim-lsc#180]: https://github.com/natebosch/vim-lsc/issues/180
[coc.nvim]: https://github.com/neoclide/coc.nvim/
[`govim`]: https://github.com/myitcv/govim
[govim-install]: https://github.com/myitcv/govim/blob/master/README.md#govim---go-development-plugin-for-vim8
[nvim-docs]: https://neovim.io/doc/user/lsp.html
[nvim-install]: https://github.com/neovim/neovim/wiki/Installing-Neovim
[nvim-lspconfig]: https://github.com/neovim/nvim-lspconfig/blob/master/doc/configs.md#gopls
[nvim-lspconfig-imports]: https://github.com/neovim/nvim-lspconfig/issues/115


================================================
FILE: gopls/doc/editor/zed.md
================================================
---
title: "Gopls: Using Zed"
---

## Install `gopls`

To use `gopls` with [Zed](https://zed.dev/), first
[install the `gopls` executable](../index.md#installation) and ensure that the directory
containing the resulting binary (either `$(go env GOBIN)` or `$(go env
GOPATH)/bin`) is in your `PATH`.

## That's it

Zed has a built-in LSP client and knows to run `gopls` when visiting a
Go source file, so most features work right out of the box.

Zed does not yet support external `window/showDocument` requests,
so web-based features will not work;
see [Zed issue 24852](https://github.com/zed-industries/zed/discussions/24852).


================================================
FILE: gopls/doc/features/README.md
================================================
See [index.md](index.md).


================================================
FILE: gopls/doc/features/assembly.md
================================================
---
title: "Gopls: Support for Go *.s assembly files"
---

Gopls has rudimentary support for LSP operations in Go assembly files.

Go assembly files have a `.s` file name extension. LSP clients need to
be configured to recognize `.s` files as Go assembly files, since this
file name extension is also used for assembly files in other
languages. A good heuristic is that if a file named `*.s` belongs to a
directory containing at least one `*.go` file, then the `.s` file is
Go assembly, and its appropriate language server is gopls.

Only Definition (`textDocument/definition`) requests are currently
supported. For example, a Definition request on the `sigpanic`
symbol in this file in GOROOT/src/runtime/asm.s:

```asm
	JMP	·sigpanic<ABIInternal>(SB)
```

returns the location of the function declaration in
GOROOT/src/runtime/signal_unix.go:

```go
//go:linkname sigpanic
func sigpanic() {
```

See also issue https://go.dev/issue/71754, which tracks the development of LSP
features in Go assembly files.

================================================
FILE: gopls/doc/features/completion.md
================================================
---
title: "Gopls: Completion"
---

TODO(https://go.dev/issue/62022): document


================================================
FILE: gopls/doc/features/diagnostics.md
================================================
---
title: "Gopls: Diagnostics"
---

Gopls continuously annotates all your open files of source code with a
variety of diagnostics. Every time you edit a file or make a
configuration change, gopls asynchronously recomputes these
diagnostics and sends them to the client using the LSP
[`publishDiagnostics`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_publishDiagnostics)
notification, giving you real-time feedback that reduces the cost of
common mistakes.

Diagnostics come from two main sources: compilation errors and analysis findings.

- **Compilation errors** are those that you would obtain from running `go
build`. Gopls doesn't actually run the compiler; that would be too
  slow. Instead it runs `go list` (when needed) to compute the
  metadata of the compilation, then processes those packages in a similar
  manner to the compiler front-end: reading, scanning, and parsing the
  source files, then type-checking them. Each of these steps can
  produce errors that gopls will surface as a diagnostic.

  The `source` field of the LSP `Diagnostic` record indicates where
  the diagnostic came from: those with source `"go list"` come from
  the `go list` command, and those with source `"compiler"` come from
  gopls' parsing or type checking phases, which are similar to those
  used in the Go compiler.

  ![A diagnostic due to a type error](../assets/diagnostic-typeerror.png)

  The example above shows a `string + int` addition, causes the type
  checker to report a `MismatchedTypes` error. The diagnostic contains
  a link to the documentation about this class of type error.

- **Analysis findings** come from the [**Go analysis
  framework**](https://golang.org/x/tools/go/analysis), the system
  used by `go vet` to apply a variety of additional static checks to
  your Go code. The best-known example is the [`printf`
  analyzer](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/printf),
  which reports calls to [`fmt.Printf`](https://pkg.go.dev/fmt#Printf)
  where the format "verb" doesn't match the argument, such as
  `fmt.Printf("%d", "three")`.

  Gopls provides dozens of analyzers aggregated from a variety of
  suites; see [Analyzers](../analyzers.md) for the complete list. The
  `source` field of each diagnostic produced by an analyzer records
  the name of the analyzer that produced it.

  ![A diagnostic due to an analysis finding](../assets/diagnostic-analysis.png)

  The example above shows a `printf` formatting mistake. The diagnostic contains
  a link to the documentation for the `printf` analyzer.

There is an optional third source of diagnostics:

<a id='toggleCompilerOptDetails'></a>

- **Compiler optimization details** are diagnostics that report
  details relevant to optimization decisions made by the Go
  compiler, such as whether a variable escapes or a slice index
  requires a bounds check.

  Optimization decisions include:
  whether a variable escapes, and how escape is inferred;
  whether a nil-pointer check is implied or eliminated; and
  whether a function can be inlined.

  This source is disabled by default but can be enabled on a
  package-by-package basis by invoking the
  `source.toggleCompilerOptDetails` ("{Show,Hide} compiler optimization
  details") code action.

  Remember that the compiler's optimizer runs only on packages that
  are transitively free from errors, so optimization diagnostics
  will not be shown on packages that do not build.


## Recomputation of diagnostics

By default, diagnostics are automatically recomputed each time the source files
are edited.

Compilation errors in open files are updated after a very short delay
(tens of milliseconds) after each file change, potentially after every keystroke.
This ensures rapid feedback of syntax and type errors while editing.

Compilation and analysis diagnostics for the whole workspace are much
more expensive to compute, so they are usually recomputed after a
short idle period (around 1s) following an edit.

The [`diagnosticsDelay`](../settings.md#diagnosticsDelay) setting determines
this period.
Alternatively, diagnostics may be triggered only after an edited file
is saved, using the
[`diagnosticsTrigger`](../settings.md#diagnosticsTrigger) setting.

When initialized with `"pullDiagnostics": true`, gopls also supports
["pull diagnostics"](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_pullDiagnostics),
an alternative mechanism for recomputing diagnostics in which the client
requests diagnostics from gopls explicitly using the `textDocument/diagnostic`
request. This feature is off by default until the performance of pull
diagnostics is comparable to push diagnostics.

## Quick fixes

Each analyzer diagnostic may suggest one or more alternative
ways to fix the problem by editing the code.
For example, when a `return` statement has too few operands,
the [`fillreturns`](../analyzers.md#fillreturns) analyzer
suggests a fix that heuristically fills in the missing ones
with suitable values. Applying the fix eliminates the compilation error.

![An analyzer diagnostic with two alternative fixes](../assets/remove-unusedparam-before.png)

The screenshot above shows VS Code's Quick Fix menu for an "unused
parameter" analysis diagnostic with two alternative fixes.
(See [Remove unused parameter](transformation.md#remove-unused-parameter) for more detail.)

Suggested fixes that are indisputably safe are [code
actions](transformation.md#code-actions) whose kind is
`"source.fixAll"`.
Many client editors have a shortcut to apply all such fixes.

<!-- Note: each Code Action has exactly one kind, so a server
     must offer each "safe" action twice, once with its usual kind
     and once with kind "source.fixAll".
     The only ones in gopls are simplify{compositelit,range,slice},
     which are fixAll + quickfix.
-->

TODO(adonovan): audit all the analyzers to ensure that their
documentation is up-to-date w.r.t. any fixes they suggest.

Settings:

- The [`diagnosticsDelay`](../settings.md#diagnosticsDelay) setting determines
  the idle period after an edit before diagnostics are recomputed.
- The [`diagnosticsTriggerr`](../settings.md#diagnosticsTrigger) setting determines
  what events cause recomputation of diagnostics.
- The [`linkTarget`](../settings.md#linkTarget) setting specifies
  the base URI for Go package links in the Diagnostic.CodeDescription field.

Client support:

- **VS Code**: Each diagnostic appears as a squiggly underline.
  Hovering reveals the details, along with any suggested fixes.
- **Emacs + eglot**: Each diagnostic appears as a squiggly underline.
  Hovering reveals the details. Use `M-x eglot-code-action-quickfix`
  to apply available fixes; it will prompt if there are more than one.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls check file.go`

<!-- Below we list any quick fixes (by their internal fix name)
     that aren't analyzers. -->

### `stubMissingInterfaceMethods`: Declare missing methods of I

When a value of a concrete type is assigned to a variable of an
interface type, but the concrete type does not possess all the
necessary methods, the type checker will report a "missing method"
error.

In this situation, gopls offers a quick fix to add stub declarations
of all the missing methods to the concrete type so that it implements
the interface.

For example, this function will not compile because the value
`NegativeErr{}` does not implement the "error" interface:

```go
func sqrt(x float64) (float64, error) {
	if x < 0 {
		return 0, NegativeErr{} // error: missing method
	}
	...
}

type NegativeErr struct{}
```

Gopls will offer a quick fix to declare this method:

```go

// Error implements [error.Error].
func (NegativeErr) Error() string {
	panic("unimplemented")
}
```

Beware that the new declarations appear alongside the concrete type,
which may be in a different file or even package from the cursor
position.
(Perhaps gopls should send a `showDocument` request to navigate the
client there, or a progress notification indicating that something
happened.)

### `StubMissingCalledFunction`: Declare missing method T.f

When you attempt to call a method on a type that does not have that method,
the compiler will report an error such as "type X has no field or method Y".
In this scenario, gopls now offers a quick fix to generate a stub declaration of
the missing method, inferring its type from the call.

Consider the following code where `Foo` does not have a method `bar`:

```go
type Foo struct{}

func main() {
  var s string
  f := Foo{}
  s = f.bar("str", 42) // error: f.bar undefined (type Foo has no field or method bar)
}
```

Gopls will offer a quick fix, "Declare missing method Foo.bar".
When invoked, it creates the following declaration:

```go
func (f Foo) bar(s string, i int) string {
	panic("unimplemented")
}
```

### `CreateUndeclared`: Create missing declaration for "undeclared name: X"

A Go compiler error "undeclared name: X" indicates that a variable or function is being used before
it has been declared in the current scope. In this scenario, gopls offers a quick fix to create the declaration.

#### Declare a new variable

When you reference a variable that hasn't been declared:

```go
func main() {
  x := 42
  min(x, y) // error: undefined: y
}
```

The quick fix would insert a declaration with a default
value inferring its type from the context:

```go
func main() {
  x := 42
  y := 0
  min(x, y)
}
```

#### Declare a new function

Similarly, if you call a function that hasn't been declared:

```go
func main() {
  var s string
  s = doSomething(42) // error: undefined: doSomething
}
```

Gopls will insert a new function declaration below,
inferring its type from the call:

```go
func main() {
  var s string
  s = doSomething(42)
}

func doSomething(i int) string {
  panic("unimplemented")
}
```
<!--

dorky details and deletia:

- The **vet suite**, of about thirty analyzers
  designed to catch likely mistakes in your code.

- **Type-error fixers**. These are gopls-specific analyzers that
  enrich diagnostics from the type checker by suggesting fixes for
  simple problems.

  For example, when a return statement has too few operands, the
  [fillreturns](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillreturns) analyzer can heuristically fill in the missing ones
  with suitable values.

  The actual diagnostics are produced by the type checker,
  so these analyzers won't cause you to see any new diagnostics;
  but they add fixes to existing ones.
  (The user needs to know this because the settings expose it.)

  currently: fillreturns nonewvars noresultvalues stubmethods undeclaredname unusedvariable

- **Simplifiers**. These are gopls-specific analyzers that
  suggest ways to rewrite your code more simply.
  They do not indicate a mistake in your code,
  which is why they are not part of `go vet`.

  For example, the `simplifyrange` analyzer will eliminate the
  unnecessary blank variable in `for _ = range v {...}`.

  currently: simplifycompositelit simplifyrange simplifyslice unusedparams infertypeargs

- **Bug detectors**. Gopls has a suite of bug-detecting analyzers that
    can't be part of vet for some reason. That might be because they
    have dependencies that vet cannot have (e.g. nilness and
    unusedwrite, which construct SSA), or because they are tightly
    integrated with gopls (e.g. embeddirective, which produces lazy
    fixes through the code action mechanism
    [But others do that too:  undeclaredname embeddirective unusedparams stubmethods]

  currently: atomicalign deepequalerrors nilness sortslice unusedwrite embeddirective

- **staticcheck**: four suites (S=simple, SA=static analysis, QF=quickfix, ST=stylecheck)
  Only a hand-picked subset of them are enabled by default.

- **Experimental analyzers**. Gopls has some analyzers that are not
  enabled by default, because they produce too high a rate of false
  positives. For example, fieldalignment, shadow.

Note: fillstruct is not a real analyzer.

-->


================================================
FILE: gopls/doc/features/index.md
================================================
---
title: "Gopls: Index of features"
---

This page provides an index of all supported features of gopls that
are accessible through the [language server protocol](https://microsoft.github.io/language-server-protocol/) (LSP).
It is intended for:
- **users of gopls** learning its capabilities so that they get the most out of their editor;
- **editor maintainers** adding or improving Go support in an LSP-capable editor; and
- **contributors to gopls** trying to understand how it works.

In an ideal world, Go users would not need to know that gopls or even
LSP exists, as their LSP-enabled editors would implement every facet
of the protocol and expose each feature in a natural and discoverable
way. In reality, editors vary widely in their support for LSP, so
unfortunately these documents necessarily involve many details of the
protocol.

We also list [settings](../settings.md) that affect each feature.

Most features are illustrated with reference to VS Code, but we will
briefly mention whether each feature is supported in other popular
clients, and if so, how to find it. We welcome contributions, edits,
and updates from users of any editor.

Contributors should [update this documentation](../contributing.md#documentation)
when making significant changes to existing features or when adding new ones.

- [Passive](passive.md): features that are always on and require no special action
  - [Hover](passive.md#hover): information about the symbol under the cursor
  - [Signature Help](passive.md#signature-help): type information about the enclosing function call
  - [Document Highlight](passive.md#document-highlight): highlight identifiers referring to the same symbol
  - [Inlay Hint](passive.md#inlay-hint): show implicit names of struct fields and parameter names
  - [Semantic Tokens](passive.md#semantic-tokens): report syntax information used by editors to color the text
  - [Folding Range](passive.md#folding-range): report text regions that can be "folded" (expanded/collapsed) in an editor
  - [Document Link](passive.md#document-link): extracts URLs from doc comments, strings in current file so client can linkify
- [Diagnostics](diagnostics.md): compile errors and static analysis findings
- [Navigation](navigation.md): navigation of cross-references, types, and symbols
  - [Definition](navigation.md#definition): go to definition of selected symbol
  - [Type Definition](navigation.md#type-definition): go to definition of type of selected symbol
  - [References](navigation.md#references): list references to selected symbol
  - [Implementation](navigation.md#implementation): show "implements" relationships of selected type
  - [Document Symbol](navigation.md#document-symbol): outline of symbols defined in current file
  - [Symbol](navigation.md#symbol): fuzzy search for symbol by name
  - [Selection Range](navigation.md#selection-range): select enclosing unit of syntax
  - [Call Hierarchy](navigation.md#call-hierarchy): show outgoing/incoming calls to the current function
  - [Type Hierarchy](navigation.md#type-hierarchy): show interfaces/implementations of the current type
- [Completion](completion.md): context-aware completion of identifiers, statements
- [Code transformation](transformation.md): fixes and refactorings
  - [Formatting](transformation.md#formatting): format the source code
  - [Rename](transformation.md#rename): rename a symbol or package
  - [Organize imports](transformation.md#source.organizeImports): organize the import declaration
  - [Extract](transformation.md#refactor.extract): extract selection to a new file/function/variable
  - [Inline](transformation.md#refactor.inline.call): inline a call to a function or method
  - [Miscellaneous rewrites](transformation.md#refactor.rewrite): various Go-specific refactorings
  - [Add test for func](transformation.md#source.addTest): create a test for the selected function
- [Web-based queries](web.md): commands that open a browser page
  - [Package documentation](web.md#doc): browse documentation for current Go package
  - [Free symbols](web.md#freesymbols): show symbols used by a selected block of code
  - [Assembly](web.md#assembly): show listing of assembly code for selected function
  - [Split package](web.md#splitpkg): split a package into two or more components
- Support for non-Go files:
  - [Template files](templates.md): files parsed by `text/template` and `html/template`
  - [go.mod and go.work files](modfiles.md): Go module and workspace manifests
  - [Go *.s assembly files](assembly.md): Go assembly files
- [Command-line interface](../command-line.md): CLI for debugging and scripting (unstable)
- [Model Context Protocol (MCP)](mcp.md): use some features in AI-assisted environments

You can find this page from within your editor by executing the
`gopls.doc.features` [code action](transformation.md#code-actions),
which opens it in a web browser.
In VS Code, you can find it on the "Quick fix" menu.


================================================
FILE: gopls/doc/features/mcp.md
================================================
---
title: "Gopls: Model Context Protocol support"
---

Gopls includes an experimental built-in server for the [Model Context
Protocol](https://modelcontextprotocol.io/introduction) (MCP), allowing it to
expose a subset of its functionality to AI assistants in the form of MCP tools.

## Running the MCP server

There are two modes for running this server: 'attached' and 'detached'. In
attached mode, the MCP server operates in the context of an active gopls LSP
session, and so is able to share memory with your LSP session and observe the
current unsaved buffer state. In detached mode, gopls interacts with a headless
LSP session, and therefore only sees saved files on disk.

### Attached mode

To use the 'attached' mode, run gopls with the `-mcp.listen` flag. For
example:

```
gopls serve -mcp.listen=localhost:8092
```

This exposes an HTTP based MCP server using the server-sent event transport
(SSE), available at `http://localhost:8092/sessions/1` (assuming you have only
one [session](../daemon.md) on your gopls instance).

### Detached mode

To use the 'detached' mode, run the `mcp` subcommand:

```
gopls mcp
```

This runs a standalone gopls instance that speaks MCP over stdin/stdout.

## Instructions to the model

This gopls MCP server includes model instructions for its usage, describing
workflows for interacting with Go code using its available tools. These
instructions are automatically published during the MCP server initialization,
but you may want to also load them as additional context in your AI-assisted
session, to emphasize their importance. The `-instructions` flag causes them to
be printed, so that you can do, for example:

```
gopls mcp -instructions > /path/to/contextFile.md
```

## Coding assistant setup

To use the gopls MCP server with an LLM-based coding assistant,
you need to configure the assistant's MCP client to talk to `gopls`.
Below are guides for popular assistants.

First ensure that gopls v0.20 or higher is installed and available in
your `$PATH`. Use this command to install the latest version:

```bash
$ go install golang.org/x/tools/gopls@latest
```

### Gemini CLI

For Gemini CLI, add the following configuration to
`$HOME/.gemini/extensions/go/gemini-extension.json`:

```json
{
  "name": "go",
  "version": "0.0.1",
  "mcpServers": {
    "go": {
      "command": "gopls",
      "args": ["mcp"]
    }
  },
  "contextFileName": "GEMINI.md"
}
```

Then run this command to emit the model instructions:

```bash
$ gopls mcp -instructions > ~/.gemini/extensions/go/GEMINI.md
```

To verify the connection, use the `/mcp list` command in your Gemini
session to view available tools. Alternatively, run `gemini mcp list`
from your shell to inspect active MCP servers and connection status.

### Claude Code

For Claude Code, run the following command to add `gopls` as an MCP server:

```bash
$ claude mcp add gopls -- gopls mcp
```

To verify the connection and explore available tools:

*   Type `/mcp` inside your Claude session to view the list of tools offering.
*   Run `claude mcp list` to inspect currently active MCP servers.
*   Run `claude mcp get gopls` to inspect the configuration details of the server.

## Security considerations

The gopls MCP server is a wrapper around the functionality ordinarily exposed
by gopls through the Language Server Protocol (LSP). As such, gopls' tools
may perform any of the operations gopls normally performs, including:

- reading files from the file system, and returning their contents in tool
  results (such as when providing context);
- executing the `go` command to load package information, which may result in
  calls to https://proxy.golang.org to download Go modules, and writes to go
  caches;
- writing to gopls' cache or persistent configuration files; and
- uploading weekly telemetry data **if you have opted in** to [Go telemetry](https://go.dev/doc/telemetry).

The gopls MCP server does not perform any operations not already performed by
gopls in an ordinary IDE session. Like most LSP servers, gopls does not
generally write directly to your source tree, though it may instruct the client
to apply edits. Nor does it make arbitrary requests over the network, though it
may make narrowly scoped requests to certain services such as the Go module
mirror or the Go vulnerability database, which can't readily be exploited as a
vehicle for exfiltration by a confused agent. Nevertheless, these capabilities
may require additional consideration when used as part of an AI-enabled system.


================================================
FILE: gopls/doc/features/modfiles.md
================================================
---
title: "Gopls: Support for go.mod and go.work files"
---

TODO: document these features for go.{mod,work} files:
- hover
- vulncheck
- add dependency
- update dependency
- diagnostics



================================================
FILE: gopls/doc/features/navigation.md
================================================
---
title: "Gopls: Navigation features"
---

This page documents gopls features for navigating your source code.

<!-- TODO: screenshots -->

## Definition

The LSP [`textDocument/definition`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_definition)
request returns the location of the declaration of the symbol under the cursor.
Most editors provide a command to navigate directly to that location.

A definition query also works in these unexpected places:

- On an **import path**, it returns the list of locations, of
  each package declaration in the files of the imported package.
- On a **package declaration**, it returns the location of
  the package declaration that provides the documentation of that package.
- On a symbol in a **[`go:linkname` directive](https://pkg.go.dev/cmd/compile)**,
  it returns the location of that symbol's declaration.
- On a **[doc link](https://tip.golang.org/doc/comment#doclinks)**, it returns
  (like [`hover`](passive.md#hover)) the location of the linked symbol.
- On a file name in a **[`go:embed` directive](https://pkg.go.dev/embed)**,
  it returns the location of the embedded file.
- On the declaration of a non-Go function (a `func` with no body),
  it returns the location of the assembly implementation, if any,
- On a **return statement**, it returns the location of the function's result variables.
- On a **goto**, **break**, or **continue** statement, it returns the
  location of the label, the closing brace of the relevant block statement, or the
  start of the relevant loop, respectively.

<!-- On a built-in symbol such as `append` or `unsafe.Pointer`, `definition` reports
the location of the declaration in the builtin or unsafe pseudo-packages,
which are just documentation. -->

Client support:
- **VS Code**: Use [Go to Definition](https://code.visualstudio.com/docs/editor/editingevolved#_go-to-definition) (`F12` or `⌘`-click).
  If the cursor is already at the declaration, the request is instead interpreted as "Go to References".
- **Emacs + eglot**: use [`M-x xref-find-definitions`](https://www.gnu.org/software/emacs/manual/html_node/emacs/Xref.html).
- **Vim + coc.nvim**: ??
- **CLI**: `gopls definition file.go:#offset`

## References

The LSP [`textDocument/references`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_references)
request returns the locations of all identifiers that refer to the symbol under the cursor.

The references algorithm handles various parts of syntax as follows:

- The references to a **symbol** report all uses of that symbol.
  In the case of exported symbols this may include locations in other packages.
- The references to a **package declaration** are all the
  direct imports of the package, along with all the other package
  declarations in the same package.
- It is an error to request the references to a **built-in symbol**
  such as `int` or `append`,
  as they are presumed too numerous to be of interest.
- The references to an **interface method** include references to
  concrete types that implement the interface. Similarly, the
  references to a **method of a concrete type** include references to
  corresponding interface methods.
- An **embedded field** `T` in a struct type such as `struct{T}` is
  unique in Go in that it is both a reference (to a type) and a
  definition (of a field).
  The `references` operation reports only the references to it [as a field](https://go.dev/issue/63521).
  To find references to the type, jump to the type declararation first.
- The references to a module in a **require** directive in a **go.mod** file are
  the **import** statements in packages of the main module (defined by the go.mod file) that
  import packages of the required module.

Be aware that a references query returns information only about the
build configuration used to analyze the selected file, so if you ask
for the references to a symbol defined in `foo_windows.go`, the result
will never include the file `bar_linux.go`, even if that file refers
to a symbol of the same name; see https://go.dev/issue/65755.

Clients can request that the declaration be included among the
references; most do.

Client support:
- **VS Code**: Use [`Go to References`](https://code.visualstudio.com/docs/editor/editingevolved#_peek) to quickly "peek" at the references,
  or `Find all References` to open the references panel.
- **Emacs + eglot**: Via [`xref` package](https://www.gnu.org/software/emacs/manual/html_node/emacs/Xref.html): use `M-x xref-find-references`.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls references file.go:#offset`

## Implementation

The LSP
[`textDocument/implementation`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_implementation)
request queries the relation between abstract and concrete types and
their methods.

Interfaces and concrete types are matched using method sets:

- When invoked on a reference to an **interface type**, it returns the
  location of the declaration of each type that implements
  the interface.
- When invoked on a **concrete type**,
  it returns the locations of the matching interface types.
- When invoked on an **interface method**, it returns the corresponding
  methods of the types that satisfy the interface.
- When invoked on a **concrete method**,
  it returns the locations of the matching interface methods.

For example:
- `implementation(io.Reader)` includes subinterfaces such as `io.ReadCloser`,
  and concrete implementations such as `*os.File`. It also includes
  other declarations equivalent to `io.Reader`.
- `implementation(os.File)` includes only interfaces, such as
  `io.Reader` and `io.ReadCloser`.

The LSP's Implementation feature has a built-in bias towards subtypes,
possibly because in languages such as Java and C++ the relationship
between a type and its supertypes is explicit in the syntax, so the
corresponding "Go to interfaces" operation can be achieved as sequence
of two or more "Go to definition" steps: the first to visit the type
declaration, and the rest to sequentially visit ancestors.
(See https://github.com/microsoft/language-server-protocol/issues/2037.)

In Go, where there is no syntactic relationship between two types, a
search is required when navigating in either direction between
subtypes and supertypes. The heuristic above works well in many cases,
but it is not possible to ask for the superinterfaces of
`io.ReadCloser`. For more explicit navigation between subtypes and
supertypes, use the [Type Hierarchy](#Type Hierarchy) feature.

Only non-trivial interfaces are considered; no implementations are
reported for type `any`.

Within the same package, all matching types/methods are reported.
However, across packages, only exported package-level types and their
methods are reported, so local types (whether interfaces, or struct
types with methods due to embedding) may be missing from the results.
<!-- Reason: assignability of local types such as I and J defined thus:
     package p; func P() {type I interface {...}}
     package q; func Q() {type J struct {...}}
     depends on them both being in the same types.Importer "realm",
     but that is not consistent with the "scalable" gopls design.
-->

Functions, `func` types, and dynamic function calls are matched using signatures:

- When invoked on the `func` token of a **function definition**,
  it returns the locations of the matching signature types
  and dynamic call expressions.
- When invoked on the `func` token of a **signature type**,
  it returns the locations of the matching concrete function definitions.
- When invoked on the `(` token of a **dynamic function call**,
  it returns the locations of the matching concrete function
  definitions.

If either the target type or the candidate type are generic, the
results will include the candidate type if there is any instantiation
of the two types that would allow one to implement the other.
(Note: the matcher doesn't current implement full unification, so type
parameters are treated like wildcards that may match arbitrary
types, without regard to consistency of substitutions across the
method set or even within a single method.
This may lead to occasional spurious matches.)

Since a type may be both a function type and a named type with methods
(for example, `http.HandlerFunc`), it may participate in both kinds of
implementation queries (by method-sets and function signatures).
Queries using method-sets should be invoked on the type or method name,
and queries using signatures should be invoked on a `func` or `(` token.

Client support:
- **VS Code**: Use [Go to Implementations](https://code.visualstudio.com/docs/editor/editingevolved#_go-to-implementation) (`⌘F12`).
- **Emacs + eglot**: Use `M-x eglot-find-implementation`.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls implementation file.go:#offset`


## Type Definition

The LSP
[`textDocument/typeDefinition`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_typeDefinition)
request returns the location of the type of the selected symbol.

For example, if the selection is the name `buf` of a local variable of
type `*bytes.Buffer`, a `typeDefinition` query will return the
location of the type `bytes.Buffer`.
Clients typically navigate to that location.

Type constructors such as pointer, array, slice, channel, and map are
stripped off the selected type in the search for a named type. For
example, if x is of type `chan []*T`, the reported type definition
will be that of `T`.
Similarly, if the symbol's type is a function with one "interesting"
(named, non-`error`) result type, the function's result type is used.

Gopls currently requires that a `typeDefinition` query be applied to a
symbol, not to an arbitrary expression; see https://go.dev/issue/67890 for
potential extensions of this functionality.
<!-- e.g. selecting a struct field, package name, or other piece of syntax. -->

Client support:
- **VS Code**: Use [Go to Type Definition](https://code.visualstudio.com/docs/editor/editingevolved#_go-to-implementation).
- **Emacs + eglot**: Use `M-x eglot-find-typeDefinition`.
- **Vim + coc.nvim**: ??
- **CLI**: not supported

## Document Symbol

The `textDocument/documentSymbol` LSP query reports the list of
top-level declarations in this file. Clients may use this information
to present an overview of the file, and an index for faster navigation.

Gopls responds with the
[`DocumentSymbol`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbol)
type if the client indicates
[`hierarchicalDocumentSymbolSupport`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbolClientCapabilities);
otherwise it returns a
[`SymbolInformation`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#symbolInformation).

Client support:
- **VS Code**: Use the [Outline view](https://code.visualstudio.com/docs/getstarted/userinterface#_outline-view) for navigation.
- **Emacs + eglot**: Use [`M-x imenu`](https://www.gnu.org/software/emacs/manual/html_node/emacs/Imenu.html#Imenu) to jump to a symbol.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls links file.go`


## Symbol

The
[`workspace/symbol`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_symbol)
LSP query searches an index of all the symbols in the workspace.

The default symbol matching algorithm (`fastFuzzy`), inspired by the
popular fuzzy matcher [FZF](https://github.com/junegunn/fzf), attempts
a variety of inexact matches to correct for misspellings or abbreviations in your
query. For example, it considers `DocSym` a match for `DocumentSymbol`.

<!--
It also supports the following special characters within queries:

| Character | Usage     | Match        |
| --------- | --------- | ------------ |
| `'`       | `'abc`    | exact        |
| `^`       | `^printf` | exact prefix |
| `$`       | `printf$` | exact suffix |

However, VS Code does its own fuzzy matching afterward, so these
aren't effective in that client; see golang/vscode-go#647.
-->

Settings:
- The [`symbolMatcher`](../settings.md#symbolMatcher) setting controls the algorithm used for symbol matching.
- The [`symbolStyle`](../settings.md#symbolStyle) setting controls how symbols are qualified in symbol responses.
- The [`symbolScope`](../settings.md#symbolScope) setting determines the scope of the query.
- The [`directoryFilters`](../settings.md#directoryFilters) setting specifies directories to be excluded from the search.

Client support:
- **VS Code**: Use ⌘T to open [Go to Symbol](https://code.visualstudio.com/docs/editor/editingevolved#_go-to-symbol) with workspace scope.  (Alternatively, use Ctrl-Shift-O, and add a `@` prefix to search within the file or a `#` prefix to search throughout the workspace.)
- **Emacs + eglot**: Use [`M-x xref-find-apropos`](https://www.gnu.org/software/emacs/manual/html_node/emacs/Looking-Up-Identifiers.html) to show symbols that match a search term.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls links file.go`


## Selection Range

The
[`textDocument/selectionRange`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_selectionRange)
LSP query returns information about the lexical extent of each piece
of syntax enclosing the current selection.
Clients may use it to provide an operation to expand the selection
to successively larger expressions.

Client support:
- **VSCode**: Use `⌘⇧^→` to expand the selection or `⌘⇧^←` to contract it again; watch this [video](https://www.youtube.com/watch?v=dO4SGAMl7uQ).
- **Emacs + eglot**: Not standard. Use `M-x eglot-expand-selection` defined in [this configuration snippet](https://github.com/joaotavora/eglot/discussions/1220#discussioncomment-9321061).
- **Vim + coc.nvim**: ??
- **CLI**: not supported

## Call Hierarchy

The LSP CallHierarchy mechanism consists of three queries that
together enable clients to present a hierarchical view of a portion of
the static call graph:

- [`textDocument/prepareCallHierarchy`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_prepareCallHierarchy) returns a list of [items](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyItem) for a given position, each representing a named function or method enclosing the position;
- [`callHierarchyItem/incomingCalls`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchy_incomingCalls) returns the set of call sites that call the selected item; and
- [`callHierarchy/outgoingCalls`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchy_incomingCalls) returns the set of functions called by the selected item.

Invoke the command while selecting the name in a function declaration.

Dynamic calls are not included, because it is not analytically
practical to detect them. So, beware that the results may not be
exhaustive, and perform a [References](#references) query if necessary.

The hierarchy does not consider a nested function distinct from its
enclosing named function. (Without the ability to detect dynamic
calls, it would make little sense do so.)

The screenshot below shows the outgoing call tree rooted at `f`. The
tree has been expanded to show a path from `f` to the `String` method
of `fmt.Stringer` through the guts of `fmt.Sprint:`

<img title="Outgoing calls of f" src="../assets/outgoingcalls.png" width="640">

Client support:
- **VS Code**: `Show Call Hierarchy` menu item (`⌥⇧H`) opens [Call hierarchy view](https://code.visualstudio.com/docs/cpp/cpp-ide#_call-hierarchy) (note: docs refer to C++ but the idea is the same for Go).
- **Emacs + eglot**: Not standard; install with `(package-vc-install "https://github.com/dolmens/eglot-hierarchy")`. Use `M-x eglot-hierarchy-call-hierarchy` to show the direct incoming calls to the selected function; use a prefix argument (`C-u`) to show the direct outgoing calls. There is no way to expand the tree.
- **CLI**: `gopls call_hierarchy file.go:#offset` shows outgoing and incoming calls.


## Type Hierarchy

The LSP TypeHierarchy mechanism consists of three queries that
together enable clients to present a hierarchical view of a portion of
the subtyping relation over named types.

- [`textDocument/prepareTypeHierarchy`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_prepareTypeHierarchy) returns an [item](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyItem) describing the named type at the current position;
- [`typeHierarchyItem/subtypes`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchy_subtypes) returns the set of subtypes of the selected (interface) type; and
- [`typeHierarchy/supertypes`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchy_supertypes) returns the set of supertypes (interface types) of the selected type.

Invoke the command while selecting the name of a type.

As with an Implementation query, a type hierarchy query reports
function-local types only within the same package as the query type.
Also the result does not include alias types, only defined types.

<img title="Type Hierarchy: supertypes of net.Conn" src="../assets/supertypes.png" width="400">

<img title="Type Hierarchy: subtypes of io.Writer" src="../assets/subtypes.png" width="400">

Caveats:

- The type hierarchy supports only named types and their assignability
  relation. By contrast, the Implementations request also reports the
  relation between unnamed `func` types and function declarations,
  function literals, and dynamic calls of values of those types.

Client support:
- **VS Code**: `Show Type Hierarchy` menu item opens [Type hierarchy view](https://code.visualstudio.com/docs/java/java-editing#_type-hierarchy) (note: docs refer to Java but the idea is the same for Go).
- **Emacs + eglot**: Support added in March 2025. Use `M-x eglot-show-call-hierarchy`.
- **CLI**: not yet supported.


================================================
FILE: gopls/doc/features/passive.md
================================================
---
title: "Gopls: Passive features"
---

This page documents the fundamental LSP features of gopls that may be
described as "passive", since many editors use them to continuously
provide information about your source files without requiring any
special action.

See also [Code Lenses](../codelenses.md), some of which annotate your
source code with additional information and may thus also be
considered passive features.


## Hover

The LSP [`textDocument/hover`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_hover)
query returns a	description of the code currently under the cursor, such
as its name, kind, type, value (for a constant), abbreviated
declaration (for a type), doc comment (if any), and a link to the
symbol's documentation on `pkg.go.dev`. The client may request either
plain text or Markdown.

<img src='../assets/hover-basic.png'>

Depending on the selection, the response may include additional information.
For example, hovering over a type shows its declared methods,
plus any methods promoted from embedded fields.

**Doc links**: A doc comment may refer to another symbol using square
brackets, for example `[fmt.Printf]`. Hovering over one of these
[doc links](https://go.dev/doc/comment#doclinks) reveals
information about the referenced symbol.

<img src='../assets/hover-doclink.png'>

**Struct size/offset info**: for declarations of struct types,
hovering over the name reveals the struct's size in bytes:

<img title="struct size info" src="../assets/hover-size-struct.png">

And hovering over each field name shows the size and offset of that field:

<img title="field size/offset info" src="../assets/hover-size-field.png">

This information may be useful when optimizing the layout of your data
structures, or when reading assembly files or stack traces that refer
to each field by its cryptic byte offset.

In addition, Hover reports:
- the struct's size class, which is the number of bytes actually
  allocated by the Go runtime for a single object of this type; and
- the percentage of wasted space due to suboptimal ordering of struct
  fields, if this figure is 20% or higher:

<img title="a struct with wasted space" src="../assets/hover-size-wasteful.png">

In the struct above, alignment rules require each of the two boolean
fields (1 byte) to occupy a complete word (8 bytes), leading to (7 +
7) / (3 * 8) = 58% waste.
Placing the two booleans together would save a word.
(In most structures clarity is more important than compactness, so you
should reorder fields to save space only in data structures that have
been shown by profiling to be very frequently allocated.)

**Embed directives**: hovering over the file name pattern in
[`//go:embed` directive](https://pkg.go.dev/embed), for example
`*.html`, reveals the list of file names to which the wildcard
expands.

<img src='../assets/hover-embed.png'>
<!-- NB: Emacs+eglot displays only the first line of markdown, not the useful part! -->

**Linkname directives**: a [`//go:linkname` directive](https://pkg.go.dev/cmd/compile#hdr-Compiler_Directives) creates a linker-level alias for another symbol.
Hovering over the directive shows information about the other symbol.

<img src='../assets/hover-linkname.png'>

The hover information for symbols from the standard library added
after Go 1.0 states the Go release that added the symbol.

Settings:
- The [`hoverKind`](../settings.md#hoverKind) setting controls the verbosity of documentation.
- The [`linkTarget`](../settings.md#linkTarget) setting specifies
  the base URI for Go package links

Caveats:
- It is an unfortunate limitation of the LSP that a `Hover` request
  currently includes only a position but not a selection, as this
  means it is impossible to request information about the type and
  methods of, say, the `f(x)` portion of the larger expression
  `f(x).y`. Please upvote microsoft/language-server-protocol#1466 if
  you would like to see this addressed.

Client support:
- **VS Code**: enabled by default. Displays rendered Markdown in a panel near the cursor.
- **Emacs + eglot**: enabled by default. Displays a one-line summary in the echo area.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls definition file.go:#start-#end` includes information from a Hover query.


## Signature Help

The LSP [`textDocument/signatureHelp`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_signatureHelp)
query returns information about the innermost function call enclosing
the cursor or selection, including the signature of the function and
the names, types, and documentation of each parameter.

Clients may provide this information to help remind the user of the
purpose of each parameter and their order, while reading or editing a
function call.

<img src='../assets/signature-help.png'>

Call parens are not necessary if the cursor is within an identifier
that denotes a function or method. For example, Signature Help at
`once.Do(initialize‸)` will describe `initialize`, not `once.Do`.

Client support:
- **VS Code**: enabled by default.
  Also known as "[parameter hints](https://code.visualstudio.com/api/references/vscode-api#SignatureHelpProvider)" in the [IntelliSense settings](https://code.visualstudio.com/docs/editor/intellisense#_settings).
  Displays signature and doc comment alongside Hover information.
- **Emacs + eglot**: enabled by default. Displays signature in the echo area.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls signature file.go:#start-#end`


## Document Highlight

The LSP [`textDocument/documentHighlight`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_documentHighlight)
query reports a set of source ranges that should be highlighted based
on the current cursor position or selection, to emphasize the
relationship between them.

Each of the following parts of syntax forms a set so that if you
select any one member, gopls will highlight the complete set:

- each identifier that refers to the same symbol (as in the screenshot below);
- a named result variable and all its corresponding operands of `return` statements;
- the `for`, `break`, and `continue` tokens of the same loop;
- the `switch` and `break` tokens of the same switch statement;
- the `func` keyword of a function and all of its `return` statements.

More than one of these rules may be activated by a single selection,
for example, by an identifier that is also a return operand.

Different occurrences of the same identifier may be color-coded to distinguish
"read" from "write" references to a given variable symbol.

<img src='../assets/document-highlight.png'>

Client support:
- **VS Code**: enabled by default. Triggered by cursor motion, or single click.
  (Note: double clicking activates a simple syntax-oblivious textual match.)
- **Emacs + eglot**: enabled by default. Triggered by cursor motion or selection.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls signature file.go:#start-#end`


## Inlay Hint

The LSP [`textDocument/inlayHint`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_inlayHint)
query returns a set of annotations to be spliced into the current file
that reveal implicit information.

<img src='../assets/inlayhint-parameternames.png'>

Examples:

- In a function call `f(1, 2)`, hints provide the
  names of the parameters (`parameterNames`), as in the screenshot above.
- In a call to a generic function, hints provide the type arguments
  (`functionTypeParameters`).
- In an assignment `x, y = 1, 2`, hints provide the types of the
  variables (`assignVariableTypes`).
- In a struct literal such as `Point2D{1, 2}`, hints provide the field
  names (`compositeLiteralFields`).
- In a nested composite literal `T{{...}}`, a hint provides the type of
  the inner literal, `{...}` (`compositeLiteralTypes`).
- In a `for k, v := range x {}` loop, hints provide the types of the
  variables k and v (`rangeVariableTypes`).
- For a constant expression (perhaps using `iota`), a hint provides
  its computed value (`constantValues`).

See [Inlay hints](../inlayHints.md) for a complete list with examples.

<!--
TODO: Do we really need that separate doc? We could put all the
     information here with much less fuss. It changes so rarely that a
     culture of "update the tests and docs in every CL" should be sufficient.
     IIUC, VS Code needs only the api-json representation.
-->

Settings:
- The [`hints`](../settings.md#hints) setting indicates the desired set of hints.
  To reduce distractions, its default value is empty.
  To enable hints, add one or more of the identifiers above to the hints
  map. For example:
  ```json5
  "hints": {"parameterNames": true}
  ```

Client  support:
- **VS Code**: in addition to the `hints` configuration value, VS Code provides a graphical
  configuration menu ("Preferences: Open Settings (UI)" the search for "Go Inlay Hints")
  for each supported kind of inlay hint.
- **Emacs + eglot**: disabled by default. Needs `M-x eglot-inlay-hints-mode` plus the configuration [described here](https://www.reddit.com/r/emacs/comments/11bqzvk/emacs29_and_eglot_inlay_hints/)
- **Vim + coc.nvim**: ??
- **CLI**: not supported

## Semantic Tokens

The LSP [`textDocument/semanticTokens`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_semanticTokens)
query reports information about all the tokens in the current file, or
a portion of it.
The client may use this information to provide syntax highlighting
that conveys semantic distinctions between, for example, functions and
types, constants and variables, or library functions and built-ins.

The client must specify the sets of types and modifiers it is interested in.

Gopls reports the following token types:

- `"comment"`: a comment
- `"function"`: a function
- `"keyword"`: a keyword
- `"label"`: a control label (not an LSP standard type)
- `"macro"`: text/template tokens
- `"method"`: a method
- `"namespace"`: an imported package name
- `"number"`: a numeric literal
- `"operator"`: an operator
- `"parameter"`: a parameter variable
- `"string"`:  a string literal
- `"type"`: a type name (plus other uses)
- `"typeParameter"`: a type parameter
- `"variable"`: a var or const (see `readonly` modifier)

Gopls also reports the following standard modifiers:

- `"defaultLibrary"`: predeclared symbols
- `"definition"`: the declaring identifier of a symbol
- `"readonly"`: for constants

plus these non-standard modifiers each representing the top-level
constructor of each symbols's type:

- `"array"`
- `"bool"`
- `"chan"`
- `"interface"`
- `"map"`
- `"number"`
- `"pointer"`
- `"signature"`
- `"slice"`
- `"string"`
- `"struct"`

Settings:
- The [`semanticTokens`](../settings.md#semanticTokens) setting determines whether
  gopls responds to semantic token requests. This option allows users to disable
  semantic tokens even when their client provides no client-side control over the
  feature. Because gopls' semantic-tokens algorithm depends on type checking,
  which adds a tangible latency, this feature is currently disabled by default
  to avoid any delay in syntax highlighting; see https://go.dev/issue/#45313, https://go.dev/issue/#47465.
- The experimental [`noSemanticString`](../settings.md#noSemanticString) and
  [`noSemanticNumber`](../settings.md#noSemanticNumber) settings cause the server
  to exclude the `string` and `number` kinds from the response, as some clients
  may do a more colorful job highlighting these tokens; see https://go.dev/issue/45753.

Client Support:
- **VS Code**: See [Semantic Highlighting Guide](https://code.visualstudio.com/api/language-extensions/semantic-highlight-guide).
- **Emacs + eglot**: Not supported; see joaotavora/eglot#615.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls semtok file.go`

## Folding Range

The LSP [`textDocument/foldingRange`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_foldingRange)
query reports the list of regions in the current file that may be
independently collapsed or expanded. For example, it may be convenient
to collapse large comments or functions when studying some code so
that more of it fits in a single screen.

<img title="A function FoldingRange, collapsed, in VS Code" src="../assets/foldingrange.png" width="640">

The protocol [allows](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#foldingRangeClientCapabilities) clients to indicate whether they prefer
fine-grained ranges such as matched pairs of brackets, or only ranges
consisting of complete lines.

Client support:
- **VS Code**: displayed in left margin. Toggle the chevrons (`∨` and `>`) to collapse or expand.
- **Emacs + eglot**: not supported.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls folding_ranges file.go`

## Document Link

The LSP [`textDocument/documentLink`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_documentLink)
query uses heuristics to extracts URLs from doc comments and string
literals in the current file so that the client can present them as
clickable links.

<img src='../assets/documentlink.png'>

In addition to explicit URLs, gopls also turns string literals in
import declarations into links to the pkg.go.dev documentation for the
imported package.

Settings:
- The [`importShortcut`](../settings.md#importShortcut) setting determines
  what kind of link is returned for an `import` declaration.
- The [`linkTarget`](../settings.md#linkTarget) setting specifies
  the base URI for Go package links.

Client support:
- **VS Code**: Hovering over a link displays a "Follow link (cmd+click)" popup.
- **Emacs + eglot**: not currently used.
- **Vim + coc.nvim**: ??
- **CLI**: `gopls links file.go`


================================================
FILE: gopls/doc/features/templates.md
================================================
---
title: "Gopls: Support for template files"
---

Gopls provides some support for Go template files, that is, files that
are parsed by [`text/template`](https://pkg.go.dev/text/template) or
[`html/template`](https://pkg.go.dev/html/template).

## Enabling template support

Gopls recognizes template files based on their file extension, which
may be configured by the
[`templateExtensions`](../settings.md#templateExtensions) setting. If
this list is empty, template support is disabled. (This is the default
value, since Go templates don't have a canonical file extension.)

Additional configuration may be necessary to ensure that your client
chooses the correct language kind when opening template files.
Gopls recognizes both `"tmpl"` and `"gotmpl"` for template files.
For example, in `VS Code` you will also need to add an
entry to the
[`files.associations`](https://code.visualstudio.com/docs/languages/identifiers)
mapping:
```json
"files.associations": {
  ".mytemplate": "gotmpl"
},
```


## Features
In template files, template support works inside
the default `{{` delimiters. (Go template parsing
allows the user to specify other delimiters, but
gopls does not know how to do that.)

Gopls template support includes the following features:
+ **Diagnostics**: if template parsing returns an error,
it is presented as a diagnostic. (Missing functions do not produce errors.)
+ **Syntax Highlighting**: syntax highlighting is provided for template files.
+ **Definitions**: gopls provides jump-to-definition inside templates, though it does not understand scoping (all templates are considered to be in one global scope).
+ **References**: gopls provides find-references, with the same scoping limitation as definitions.
+ **Completions**: gopls will attempt to suggest completions inside templates.

TODO: also
+ Hover
+ SemanticTokens
+ Symbol search
+ DocumentHighlight




================================================
FILE: gopls/doc/features/transformation.md
================================================
---
title: "Gopls: Code transformation features"
---

This document describes gopls' features for code transformation, which
include a range of behavior-preserving changes (refactorings,
formatting, simplifications), code repair (fixes), and editing support
(filling in struct literals and switch statements).

Code transformations are not a single category in the LSP:

- A few, such as Formatting and Rename, are primary operations in the
  protocol.
- Some transformations are exposed through [Code Lenses](../codelenses.md),
  which return _commands_, arbitrary server
  operations invoked for their side effects through a
  [`workspace/executeCommand`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_executeCommand) request;
  however, no current code lenses are transformations of Go syntax.
  <!-- Generate, RegenerateCgo (Go); Tidy, UpgradeDependency, Vendor (go.mod) -->
- Most transformations are defined as *code actions*.

## Code Actions

A **code action** is an action associated with a portion of the file.
Each time the selection changes, a typical client makes a
[`textDocument/codeAction`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_codeAction)
request for the set of available actions, then updates its UI
elements (menus, icons, tooltips) to reflect them.
The VS Code manual describes code actions as
"[Quick fixes + Refactorings](https://code.visualstudio.com/docs/editor/refactoring#_code-actions-quick-fixes-and-refactorings)".

A `codeAction` request delivers the menu, so to speak, but it does
not order the meal. Once the user chooses an action, one of two things happens.
In trivial cases, the action itself contains an edit that the
client can directly apply to the file.
But in most cases the action contains a command,
similar to the command associated with a code lens.
This allows the work of computing the patch to be done lazily, only
when actually needed. (Most aren't.)
The server may then compute the edit and send the client a
[`workspace/applyEdit`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#workspace_applyEdit)
request to patch the files.
Not all code actions' commands have an `applyEdit` side effect: some
may change the state of the server, for example to toggle a variable
or to cause the server to send other requests to the client,
such as a `showDocument` request to open a report in a web browser.

The main difference between code lenses and code actions is this:

- a `codeLens` request obtains commands for the entire file.
  Each command specifies its applicable source range,
  and typically appears as an annotation on that source range.
- a `codeAction` request obtains commands only for a particular range: the current selection.
  All the commands are presented together in a menu at that location.

Each action has a _kind_,
which is a hierarchical identifier such as `refactor.inline.call`.
Clients may filter actions based on their kind.
For example, VS Code has:
two menus, "Refactor..." and "Source action...", each populated by
different kinds of code actions (`refactor` and `source`);
a lightbulb icon that triggers a menu of "quick fixes" (of kind `quickfix`);
and a "Fix All" command that executes all code actions of
kind `source.fixAll`, which are those deemed unambiguously safe to apply.

Gopls supports the following code actions:

- `quickfix`, which applies unambiguously safe fixes <!-- TODO: document -->
- [`source.organizeImports`](#source.organizeImports)
- [`source.assembly`](web.md#assembly)
- [`source.doc`](web.md#doc)
- [`source.freesymbols`](web.md#freesymbols)
- `source.test` (undocumented) <!-- TODO: fix that -->
- [`source.addTest`](#source.addTest)
- [`source.toggleCompilerOptDetails`](diagnostics.md#toggleCompilerOptDetails)
- [`gopls.doc.features`](README.md), which opens gopls' index of features in a browser
- [`refactor.extract.constant`](#extract)
- [`refactor.extract.function`](#extract)
- [`refactor.extract.method`](#extract)
- [`refactor.extract.toNewFile`](#extract.toNewFile)
- [`refactor.extract.variable`](#extract)
- [`refactor.extract.variable-all`](#extract)
- [`refactor.inline.call`](#refactor.inline.call)
- [`refactor.inline.variable`](#refactor.inline.variable)
- [`refactor.rewrite.addTags`](#refactor.rewrite.addTags)
- [`refactor.rewrite.changeQuote`](#refactor.rewrite.changeQuote)
- [`refactor.rewrite.fillStruct`](#refactor.rewrite.fillStruct)
- [`refactor.rewrite.fillSwitch`](#refactor.rewrite.fillSwitch)
- [`refactor.rewrite.invertIf`](#refactor.rewrite.invertIf)
- [`refactor.rewrite.joinLines`](#refactor.rewrite.joinLines)
- [`refactor.rewrite.moveParamLeft`](#refactor.rewrite.moveParamLeft)
- [`refactor.rewrite.moveParamRight`](#refactor.rewrite.moveParamRight)
- [`refactor.rewrite.removeTags`](#refactor.rewrite.removeTags)
- [`refactor.rewrite.removeUnusedParam`](#refactor.rewrite.removeUnusedParam)
- [`refactor.rewrite.splitLines`](#refactor.rewrite.splitLines)

Gopls reports some code actions twice, with two different kinds, so
that they appear in multiple UI elements: simplifications,
for example from `for _ = range m` to `for range m`,
have kinds `quickfix` and `source.fixAll`,
so they appear in the "Quick Fix" menu and
are activated by the "Fix All" command.

<!-- In principle the filter may include the trigger event
     e.g. auto (cursor motion) vs. invoked (open a menu)
     but gopls currently ignores it. -->

Many transformations are computed by [analyzers](../analyzers.md)
that, in the course of reporting a diagnostic about a problem,
also suggest a fix.
A `codeActions` request will return any fixes accompanying diagnostics
for the current selection.

<!-- Some gopls-internal analyzers compute fixes lazily by
     reporting an empty list of TextEdits and a Diagnostic.Category
     recognized by gopls that enables corresponding logic in the
     server's ApplyFix command handler. -->

<!-- The source.test ("Run this test") code action (not a
     transformation) runs the selected test. However, it is not
     offered by default because:
     (a) VS Code has a richer test UX (with richer ones to come--see
         https://github.com/golang/vscode-go/issues/1641) and
     (b) LSP has no good way to display the streaming output of a test
         in the client's natural UX (see last paragraph of first note
	 of https://github.com/golang/go/issues/67400).
     It is only offered when the "only" field includes kind source.test.
     Should it be documented? If so, where?
-->

Caveats:

- Many of gopls code transformations are limited by Go's syntax tree
  representation, which currently records comments not in the tree
  but in a side table; consequently, transformations such as Extract
  and Inline are prone to losing comments. This is issue
  https://go.dev/issue/20744, and it is a priority for us to fix in 2024.

- Generated files, as identified by the conventional
  [DO NOT EDIT](https://go.dev/s/generatedcode) comment,
  are not offered code actions for transformations.
  <!-- TODO: this is frankly a nuisance. It is often convenient to modify generated files -->

Client support for code actions:

- **VS Code**: Depending on their kind, code actions are found in
  the "Refactor..." menu (`^⇧R`),
  the "Source action..." menu,
  the 💡 (light bulb) icon's menu, or
  the "Quick fix" (`⌘.`) menu.
  The "Fix All" command applies all actions of kind `source.fixAll`.
- **Emacs + eglot**: Code actions are invisible.
  Use `M-x eglot-code-actions` to select one from those that are
  available (if there are multiple) and execute it.
  Some action kinds have filtering shortcuts,
  e.g. [`M-x eglot-code-action-{inline,extract,rewrite}`](https://joaotavora.github.io/eglot/#index-M_002dx-eglot_002dcode_002daction_002dinline).
- **CLI**: `gopls codeaction -exec -kind k,... -diff file.go:#123-#456` executes code actions of the specified
  kinds (e.g. `refactor.inline`) on the selected range, specified using zero-based byte offsets, and displays the diff.

<a name='formatting'></a>
## Formatting

The LSP
[`textDocument/formatting`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_formatting)
request returns edits that format a file.
Gopls applies Go's canonical formatting algorithm,
[`go fmt`](https://pkg.go.dev/cmd/gofmt).
LSP formatting options are ignored.

Most clients are configured to format files and organize imports
whenever a file is saved.

Settings:

- The [`gofumpt`](../settings.md#gofumpt) setting causes gopls to use an
  alternative formatter, [`github.com/mvdan/gofumpt`](https://pkg.go.dev/mvdan.cc/gofumpt).

Client support:

- **VS Code**: Formats on save by default. Use `Format document` menu item (`⌥⇧F`) to invoke manually.
- **Emacs + eglot**: Use `M-x eglot-format-buffer` to format. Attach it to `before-save-hook` to format on save. For formatting combined with organize-imports, many users take the legacy approach of setting `"goimports"` as their `gofmt-command` using [go-mode](https://github.com/dominikh/go-mode.el), and adding `gofmt-before-save` to `before-save-hook`. An LSP-based solution requires code such as https://github.com/joaotavora/eglot/discussions/1409.
- **CLI**: `gopls format file.go`

<a name='source.organizeImports'></a>
## `source.organizeImports`: Organize imports

A `codeActions` request in a file whose imports are not organized will
return an action of the standard kind `source.organizeImports`.
Its command has the effect of organizing the imports:
deleting existing imports that are duplicate or unused,
adding new ones for undefined symbols,
and sorting them into the conventional order.

The addition of new imports is based on heuristics that depend on
your workspace and the contents of your GOMODCACHE directory; they may
sometimes make surprising choices.

Many editors automatically organize imports and format the code before
saving any edited file.

Some users dislike the automatic removal of imports that are
unreferenced because, for example, the sole line that refers to the
import is temporarily commented out for debugging; see https://go.dev/issue/54362.

Settings:

- The [`local`](../settings.md#local) setting is a comma-separated list of
  prefixes of import paths that are "local" to the current file and
  should appear after standard and third-party packages in the sort order.

Client support:

- **VS Code**: automatically invokes `source.organizeImports` before save.
  To disable it, use the snippet below, and invoke the "Organize Imports" command manually as needed.
  ```
  "[go]": {
    "editor.codeActionsOnSave": { "source.organizeImports": false }
  }
  ```
- **Emacs + eglot**: Use `M-x eglot-code-action-organize-imports` to invoke manually.
  Many users of [go-mode](https://github.com/dominikh/go-mode.el) use these lines to
  organize imports and reformat each modified file before saving it, but this
  approach is based on the legacy
  [`goimports`](https://pkg.go.dev/golang.org/x/tools/cmd/goimports) tool, not gopls:
  ```lisp
  (setq gofmt-command "goimports")
  (add-hook 'before-save-hook 'gofmt-before-save)
  ```
- **CLI**: `gopls fix -a file.go:#offset source.organizeImports`

<a name='source.addTest'></a>
## `source.addTest`: Add test for function or method

If the selected chunk of code is part of a function or method declaration F,
gopls will offer the "Add test for F" code action, which adds a new test for the
selected function in the corresponding `_test.go` file. The generated test takes
into account its signature, including input parameters and results.

**Test file**: if the `_test.go` file does not exist, gopls creates it, based on
the name of the current file (`a.go` -> `a_test.go`), copying any copyright and
build constraint comments from the original file.

**Test package**: for new files that test code in package `p`, the test file
uses `p_test` package name whenever possible, to encourage testing only exported
functions. (If the test file already exists, the new test is added to that file.)

**Parameters**: each of the function's non-blank parameters becomes an item in
the struct used for the table-driven test. (For each blank `_` parameter, the
value has no effect, so the test provides a zero-valued argument.)

**Contexts**: If the first parameter is `context.Context`, the test passes
`context.Background()`.

**Results**: the function's results are assigned to variables (`got`, `got2`,
and so on) and compared with expected values (`want`, `want2`, etc.`) defined in
the test case struct. The user should edit the logic to perform the appropriate
comparison. If the final result is an `error`, the test case defines a `wantErr`
boolean.

**Method receivers**: When testing a method `T.F` or `(*T).F`, the test must
construct an instance of T to pass as the receiver. Gopls searches the package
for a suitable function that constructs a value of type T or \*T, optionally with
an error, preferring a function named `NewT`.

**Imports**: Gopls adds missing imports to the test file, using the last
corresponding import specifier from the original file. It avoids duplicate
imports, preserving any existing imports in the test file.

<img title="Add test for func" src="../assets/add-test-for-func.png" width='80%'>

<a name='rename'></a>
## Rename

The LSP
[`textDocument/rename`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_rename)
request renames a symbol.

Renaming is a two-stage process. The first step, a
[`prepareRename`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareRename) query, returns the current
name of the identifier under the cursor (if indeed there is one).
The client then displays a dialog prompting the user to choose a new
name by editing the old one. The second step, `rename` proper, applies
the changes. (This simple dialog support is unique among LSP
refactoring operations; see microsoft/language-server-protocol#1164.)

Gopls' renaming algorithm takes great care to detect situations in
which renaming might introduce a compilation error.
For example, changing a name may cause a symbol to become "shadowed",
so that some existing references are no longer in scope. Gopls will
report an error, stating the pair of symbols and the shadowed reference:

<img title="Renamed failed due to a shadowing conflict" src="../assets/rename-conflict.png">

As another example, consider renaming a method of a concrete type.
Renaming may cause the type to no longer satisfy the same interfaces
as before, which could cause the program to fail to compile.
To avoid this, gopls inspects each conversion (explicit or implicit)
from the affected type to an interface type, and checks whether it
would remain valid after the renaming. If not, it aborts the renaming
with an error.

If you intend to rename both the original method and the corresponding
methods of any matching interface types (as well as any methods of
types matching them in turn), you can indicate this by invoking the
rename operation on the interface method.

Similarly, gopls will report an error if you rename a field of a
struct that happens to be an "anonymous" field that embeds a type,
since that would require a larger renaming involving the type as well.
If that is what you intend, you can again indicate this by
invoking the rename operation on the type.

Renaming should never introduce a compilation error, but it may
introduce dynamic errors. For example, in a method renaming, if there
is no direct conversion of the affected type to the interface type,
but there is an intermediate conversion to a broader type (such as `any`) followed by a
type assertion to the interface type, then gopls may proceed to rename
the method, causing the type assertion to fail at run time.
Similar problems may arise with packages that use reflection, such as
`encoding/json` or `text/template`. There is no substitute for good
judgment and testing.

Special cases:

- When renaming the declaration of a method receiver, the tool also
  attempts to rename the receivers of all other methods associated
  with the same named type. Each other receiver that cannot be fully
  renamed is quietly skipped. Renaming any _use_ of a receiver affects
  only that variable.

  ```go
  type Counter struct { x int }

                   Rename here to affect only this method
                            ↓
  func (c *Counter) Inc() { c.x++ }
  func (c *Counter) Dec() { c.x++ }
        ↑
    Rename here to affect all methods
  ```

Using Rename to move a package:
To rename a package, execute the Rename operation over the `p` in a
`package p` declaration at the start of a file.
You will be prompted to edit the package's path and choose its new location.
The Rename operation will move all the package's files to the resulting directory,
creating it if necessary.
By default, subpackages will remain where they are. To include subpackages
in the renaming, set [renameMovesSubpackages](../settings.md#renamemovessubpackages-bool) to true.
Existing imports of the package will be updated to reflect its new path.

Package moves are rejected if they would break the build. For example:
- Packages cannot move across a module boundary.
- Packages cannot be moved into existing packages; gopls does not support package merging.
- Packages cannot be moved to internal directories that would make them inaccessible to any of their current importers.

Renaming package main is not supported, because the main package has special meaning to the linker.
Renaming x_test packages is currently not supported.

Some tips for best results:

- The safety checks performed by the Rename algorithm require type
  information. If the program is grossly malformed, there may be
  insufficient information for it to run (https://go.dev/issue/41870),
  and renaming cannot generally be used to fix a type error (https://go.dev/issue/41851).
  When refactoring, we recommend working in small steps, repairing any
  problems as you go, so that as much as possible of the program
  compiles at each step.
- Sometimes it may be desirable for a renaming operation to change the
  reference structure of the program, for example to intentionally
  combine two variables x and y by renaming y to x.
  The renaming tool is too strict to help in this case (https://go.dev/issue/41852).

<!-- known issue: when renaming an interface method, gopls doesn't properly
     traverse W-shaped import graphs looking for matching types; see https://go.dev/issue/58461. -->

For the gory details of gopls' rename algorithm, you may be interested
in the latter half of this 2015 GothamGo talk:
[Using go/types for Code Comprehension and Refactoring Tools](https://www.youtube.com/watch?v=p_cz7AxVdfg).

Client support:

- **VS Code**: Use "[Rename symbol](https://code.visualstudio.com/docs/editor/editingevolved#_rename-symbol)" menu item (`F2`).
- **Emacs + eglot**: Use `M-x eglot-rename`, or `M-x go-rename` from [go-mode](https://github.com/dominikh/go-mode.el).
- **Vim + coc.nvim**: Use the `coc-rename` command.
- **CLI**: `gopls rename file.go:#offset newname`

<a name='refactor.extract'></a>
## `refactor.extract`: Extract function/method/variable

The `refactor.extract` family of code actions all return commands that
replace the selected expression or statements with a reference to a
newly created declaration that contains the selected code:

- **`refactor.extract.function`** replaces one or more complete statements by a
  call to a new function named `newFunction` whose body contains the
  statements. The selection must enclose fewer statements than the
  entire body of the existing function.

  ![Before extracting a function](../assets/extract-function-before.png)
  ![After extracting a function](../assets/extract-function-after.png)

- **`refactor.extract.method`** is a variant of "Extract function" offered when
  the selected statements belong to a method. The newly created function
  will be a method of the same receiver type.

- **`refactor.extract.variable`** replaces an expression by a reference to a new
  local variable named `newVar` initialized by the expression:

  ![Before extracting a var](../assets/extract-var-before.png)
  ![After extracting a var](../assets/extract-var-after.png)

- **`refactor.extract.constant** does the same thing for a constant
  expression, introducing a local const declaration.
- **`refactor.extract.variable-all`** replaces all occurrences of the selected expression
within the function with a reference to a new local variable named `newVar`.
This extracts the expression once and reuses it wherever it appears in the function.

  ![Before extracting all occurrences of EXPR](../assets/extract-var-all-before.png)
  ![After extracting all occurrences of EXPR](../assets/extract-var-all-after.png)

  - **`refactor.extract.constant-all** does the same thing for a constant
  expression, introducing a local const declaration.
If the default name for the new declaration is already in use, gopls
generates a fresh name.

Extraction is a challenging problem requiring consideration of
identifier scope and shadowing, control
flow such as `break`/`continue` in a loop or `return` in a
function, cardinality of variables, and even subtle issues of style.
In each case, the tool will try to update the extracted statements
as needed to avoid build breakage or behavior changes.
Unfortunately, gopls' Extract algorithms are considerably less
rigorous than the Rename and Inline operations, and we are aware of a
number of cases where it falls short, including:

- https://github.com/golang/go/issues/66289
- https://github.com/golang/go/issues/65944
- https://github.com/golang/go/issues/63394
- https://github.com/golang/go/issues/61496

The following Extract features are planned for 2024 but not yet supported:

- **Extract parameter struct** will replace two or more parameters of a
  function by a struct type with one field per parameter; see https://go.dev/issue/65552.
  <!-- TODO(adonovan): review and land https://go.dev/cl/620995. -->
  <!-- Should this operation update all callers? That's more of a Change Signature. -->
- **Extract interface for type** will create a declaration of an
  interface type with all the methods of the selected concrete type;
  see https://go.dev/issue/65721 and https://go.dev/issue/46665.

<a name='refactor.extract.toNewFile'></a>
## `refactor.extract.toNewFile`: Extract declarations to new file

(Available from gopls/v0.17.0)

If you select one or more top-level declarations, gopls will offer an
"Extract declarations to new file" code action that moves the selected
declarations into a new file whose name is based on the first declared
symbol.
Import declarations are created as needed.
Gopls also offers this code action when the selection is just the
first token of the declaration, such as `func` or `type`.

![Before: select the declarations to move](../assets/extract-to-new-file-before.png)
![After: the new file is based on the first symbol name](../assets/extract-to-new-file-after.png)

<a name='refactor.inline.call'></a>

## `refactor.inline.call`: Inline call to function

For a `codeActions` request where the selection is (or is within) a
call of a function or method, gopls will return a command of kind
`refactor.inline.call`, whose effect is to inline the function call.

The screenshots below show a call to `sum` before and after inlining:

<!-- source code used for images:

func six() int {
	return sum(1, 2, 3)
}

func sum(values ...int) int {
	total := 0
	for _, v := range values {
		total += v
	}
	return total
}
-->

![Before: select Refactor... Inline call to sum](../assets/inline-before.png)
![After: the call has been replaced by the sum logic](../assets/inline-after.png)

Inlining replaces the call expression by a copy of the function body,
with parameters replaced by arguments.
Inlining is useful for a number of reasons.
Perhaps you want to eliminate a call to a deprecated
function such as `ioutil.ReadFile` by replacing it with a call to the
newer `os.ReadFile`; inlining will do that for you.
Or perhaps you want to copy and modify an existing function in some
way; inlining can provide a starting point.
The inlining logic also provides a building block for
other refactorings, such as "change signature".

Not every call can be inlined.
Of course, the tool needs to know which function is being called, so
you can't inline a dynamic call through a function value or interface
method; but static calls to methods are fine.
Nor can you inline a call if the callee is declared in another package
and refers to non-exported parts of that package, or to [internal
packages](https://go.dev/doc/go1.4#internalpackages) that are
inaccessible to the caller.
Calls to generic functions are not yet supported
(https://go.dev/issue/63352), though we plan to fix that.

When inlining is possible, it's critical that the tool preserve
the original behavior of the program.
We don't want refactoring to break the build, or, worse, to introduce
subtle latent bugs.
This is especially important when inlining tools are used to perform
automated clean-ups in large code bases;
we must be able to trust the tool.
Our inliner is very careful not to make guesses or unsound
assumptions about the behavior of the code.
However, that does mean it sometimes produces a change that differs
from what someone with expert knowledge of the same code might have
written by hand.

In the most difficult cases, especially with complex control flow, it
may not be safe to eliminate the function call at all.
For example, the behavior of a `defer` statement is intimately tied to
its enclosing function call, and `defer` is the only control
construct that can be used to handle panics, so it cannot be reduced
into simpler constructs.
So, for example, given a function f defined as:

```go
func f(s string) {
	defer fmt.Println("goodbye")
	fmt.Println(s)
}
```

a call `f("hello")` will be inlined to:

```go
	func() {
		defer fmt.Println("goodbye")
		fmt.Println("hello")
	}()
```

Although the parameter was eliminated, the function call remains.

An inliner is a bit like an optimizing compiler.
A compiler is considered "correct" if it doesn't change the meaning of
the program in translation from source language to target language.
An _optimizing_ compiler exploits the particulars of the input to
generate better code, where "better" usually means more efficient.
As users report inputs that cause the compiler to emit suboptimal
code, the compiler is improved to recognize more cases, or more rules,
and more exceptions to rules---but this process has no end.
Inlining is similar, except that "better" code means tidier code.
The most conservative translation provides a simple but (hopefully)
correct foundation, on top of which endless rules, and exceptions to
rules, can embellish and improve the quality of the output.

Here are some of the technical challenges involved in sound inlining:

- **Effects:** When replacing a parameter by its argument expression,
  we must be careful not to change the effects of the call. For
  example, if we call a function `func twice(x int) int { return x + x }`
  with `twice(g())`, we do not want to see `g() + g()`, which would
  cause g's effects to occur twice, and potentially each call might
  return a different value. All effects must occur the same number of
  times, and in the same order. This requires analyzing both the
  arguments and the callee function to determine whether they are
  "pure", whether they read variables, or whether (and when) they
  update them too. The inliner will introduce a declaration such as
  `var x int = g()` when it cannot prove that it is safe to substitute
  the argument throughout.

- **Constants:** If inlining always replaced a parameter by its argument
  when the value is constant, some programs would no longer build
  because checks previously done at run time would happen at compile time.
  For example `func index(s string, i int) byte { return s[i] }`
  is a valid function, but if inlining were to replace the call `index("abc", 3)`
  by the expression `"abc"[3]`, the compiler will report that the
  index `3` is out of bounds for the string `"abc"`.
  The inliner will prevent substitution of parameters by problematic
  constant arguments, again introducing a `var` declaration instead.

- **Referential integrity:** When a parameter variable is replaced by
  its argument expression, we must ensure that any names in the
  argument expression continue to refer to the same thing---not to a
  different declaration in the callee function body that happens to
  use the same name. The inliner must replace local references such as
  `Printf` by qualified references such as `fmt.Printf`, and add an
  import of package `fmt` as needed.

- **Implicit conversions:** When passing an argument to a function, it is
  implicitly converted to the parameter type. If we eliminate the parameter
  variable, we don't want to lose the conversion as it may be important. For
  example, in `func f(x any) { y := x; fmt.Printf("%T", &y) }` the type of
  variable y is `any`, so the program prints `"*interface{}"`. But if inlining
  the call `f(1)` were to produce the statement `y := 1`, then the type of y
  would have changed to `int`, which could cause a compile error or, as in this
  case, a bug, as the program now prints `"*int"`. When the inliner substitutes
  a parameter variable by its argument value, it may need to introduce explicit
  conversions of each value to the original parameter type, such as `y :=
  any(1)`.

- **Last reference:** When an argument expression has no effects
  and its corresponding parameter is never used, the expression
  may be eliminated. However, if the expression contains the last
  reference to a local variable at the caller, this may cause a compile
  error because the variable is now unused. So the inliner must be
  cautious about eliminating references to local variables.

This is just a taste of the problem domain. If you're curious, the
documentation for [golang.org/x/tools/internal/refactor/inline](https://pkg.go.dev/golang.org/x/tools/internal/refactor/inline) has
more detail. All of this is to say, it's a complex problem, and we aim
for correctness first of all. We've already implemented a number of
important "tidiness optimizations" and we expect more to follow.

<a name='refactor.inline.variable'></a>

## `refactor.inline.variable`: Inline local variable

For a `codeActions` request where the selection is (or is within) an
identifier that is a use of a local variable whose declaration has an
initializer expression, gopls will return a code action of kind
`refactor.inline.variable`, whose effect is to inline the variable:
that is, to replace the reference by the variable's initializer
expression.

For example, if invoked on the identifier `s` in the call `println(s)`:
```go
func f(x int) {
	s := fmt.Sprintf("+%d", x)
	println(s)
}
```
the code action transforms the code to:

```go
func f(x int) {
	s := fmt.Sprintf("+%d", x)
	println(fmt.Sprintf("+%d", x))
}
```

(In this instance, `s` becomes an unreferenced variable which you will
need to remove.)

The code action always replaces the reference by the initializer
expression, even if there are later assignments to the variable (such
as `s = ""`).

The code action reports an error if it is not possible to make the
transformation because one of the identifiers within the initializer
expression (e.g. `x` in the example above) is shadowed by an
intervening declaration, as in this example:

```go
func f(x int) {
	s := fmt.Sprintf("+%d", x)
	{
		x := 123
		println(s, x) // error: cannot replace s with fmt.Sprintf(...) since x is shadowed
	}
}
```

<a name='refactor.rewrite'></a>
## `refactor.rewrite`: Miscellaneous rewrites

This section covers a number of transformations that are accessible as
code actions whose kinds are children of `refactor.rewrite`.

<a name='refactor.rewrite.removeUnusedParam'></a>
### `refactor.rewrite.removeUnusedParam`: Remove unused parameter

The [`unusedparams` analyzer](../analyzers.md#unusedparams) reports a
diagnostic for each parameter that is not used within the function body.
For example:

```go
func f(x, y int) { // "unused parameter: x"
	fmt.Println(y)
}
```

It does _not_ report diagnostics for address-taken functions, which
may need all their parameters, even unused ones, in order to conform
to a particular function signature.
Nor does it report diagnostics for exported functions,
which may be address-taken by another package.
(A function is _address-taken_ if it is used other than in call position, `f(...)`.)

In addition to the diagnostic, it suggests two possible fixes:

1. rename the parameter to `_` to emphasize that it is unreferenced (an immediate edit); or
2. delete the parameter altogether, using a `ChangeSignature` command, updating all callers.

Fix \#2 uses the same machinery as "Inline function call" (see above)
to ensure that the behavior of all existing calls is preserved, even
when the argument expression for the deleted parameter has side
effects, as in the example below.

![The parameter x is unused](../assets/remove-unusedparam-before.png)
![The parameter x has been deleted](../assets/remove-unusedparam-after.png)

Observe that in the first call, the argument `chargeCreditCard()` was
not deleted because of potential side effects, whereas in the second
call, the argument 2, a constant, was safely deleted.

<a name='refactor.rewrite.moveParamLeft'></a>
<a name='refactor.rewrite.moveParamRight'></a>
### `refactor.rewrite.moveParam{Left,Right}`: Move function parameters

When the selection is a parameter in a function or method signature, gopls
offers a code action to move the parameter left or right (if feasible),
updating all callers accordingly.

For example:

```go
func Foo(x, y int) int {
    return x + y
}

func _() {
    _ = Foo(0, 1)
}
```

becomes

```go
func Foo(y, x int) int {
    return x + y
}

func _() {
    _ = Foo(1, 0)
}
```

following a request to move `x` right, or `y` left.

This is a primitive building block of more general "Change signature"
operations. We plan to generalize this to arbitrary signature rewriting, but
the language server protocol does not currently offer good support for user
input into refactoring operations (see
[microsoft/language-server-protocol#1164](https://github.com/microsoft/language-server-protocol/issues/1164)).
Therefore, any such refactoring will require custom client-side logic. (As a
very hacky workaround, you can express arbitrary parameter movement by invoking
Rename on the `func` keyword of a function declaration, but this interface is
just a temporary stopgap.)

<a name='refactor.rewrite.changeQuote'></a>
### `refactor.rewrite.changeQuote`: Convert string literal between raw and interpreted

When the selection is a string literal, gopls offers a code action
to convert the string between raw form (`` `abc` ``) and interpreted
form (`"abc"`) where this is possible:

![Convert to interpreted](../assets/convert-string-interpreted.png)
![Convert to raw](../assets/convert-string-raw.png)

Applying the code action a second time reverts back to the original
form.

<a name='refactor.rewrite.invertIf'></a>
### `refactor.rewrite.invertIf`: Invert 'if' condition

When the selection is within an `if`/`else` statement that is not
followed by `else if`, gopls offers a code action to invert the
statement, negating the condition and swapping the `if` and and `else`
blocks.

![Before "Invert if condition"](../assets/invert-if-before.png)
![After "Invert if condition"](../assets/invert-if-after.png)

<!-- The output of this transformation is often stylistically poor.
     For example, it will drop the "else" and outdent an if/else
     if the else block ends with a return statement; and thus applying
     the operation twice does not get you back to where you started. -->

<a name='refactor.rewrite.splitLines'></a>
<a name='refactor.rewrite.joinLines'></a>
### `refactor.rewrite.{split,join}Lines`: Split elements into separate lines

When the selection is within a bracketed list of items such as:

- the **elements** of a composite literal, `[]T{a, b, c}`,
- the **arguments** of a function call, `f(a, b, c)`,
- the **groups of parameters** of a function signature, `func(a, b, c int, d, e bool)`, or
- its **groups of results**, `func() (x, y string, z rune)`,

gopls will offer the "Split [items] into separate lines" code
action, which would transform the forms above into these forms:

```go
[]T{
	a,
	b,
	c,
}

f(
	a,
	b,
	c,
)

func(
	a, b, c int,
	d, e bool,
)

func() (
	x, y string,
	z rune,
)
```

Observe that in the last two cases, each
[group](https://pkg.go.dev/go/ast#Field) of parameters or results is
treated as a single item.

The opposite code action, "Join [items] into one line", undoes the operation.
Neither action is offered if the list is already full split or joined,
respectively, or trivial (fewer than two items).

These code actions are not offered for lists containing `//`-style
comments, which run to the end of the line.

<!-- Strictly, line comments make only "join" (but not "split") infeasible. -->

<a name='refactor.rewrite.fillStruct'></a>
### `refactor.rewrite.fillStruct`: Fill struct literal

When the cursor is within a struct literal `S{}`, gopls offers the
"Fill S" code action, which populates each missing field of the
literal that is accessible.

It uses the following heuristic to choose the value assigned to each
field: it finds candidate variables, constants, and functions that are
assignable to the field, and picks the one whose name is the closest
match to the field name.
If there are none, it uses the zero value (such as `0`, `""`, or
`nil`) of the field's type.

In the example below, a
[`slog.HandlerOptions`](https://pkg.go.dev/golang.org/x/exp/slog#HandlerOptions)
struct literal is filled in using two local variables (`level` and
`add`) and a function (`replace`):

![Before "Fill slog.HandlerOptions"](../assets/fill-struct-before.png)
![After "Fill slog.HandlerOptions"](../assets/fill-struct-after.png)

Caveats:

- This code action requires type information for the struct type, so
  if it is defined in another package that is not yet imported, you
  may need to "organize imports" first, for example by saving the
  file.
- Candidate declarations are sought only in the current file, and only
  above the current point. Symbols declared beneath the current point,
  or in other files in the package, are not considered; see
  https://go.dev/issue/68224.

<a name='refactor.rewrite.fillSwitch'></a>
### `refactor.rewrite.fillSwitch`: Fill switch

When the cursor is within a switch statement whose operand type is an
_enum_ (a finite set of named constants), or within a type switch,
gopls offers the "Add cases for T" code action, which populates the
switch statement by adding a case for each accessible named constant
of the enum type, or, for a type switch, by adding a case for each
accessible named non-interface type that implements the interface.
Only missing cases are added.

The screenshots below show a type switch whose operand has the
[`net.Addr`](https://pkg.go.dev/net#Addr) interface type. The code
action adds one case per concrete network address type, plus a default
case that panics with an informative message if an unexpected operand
is encountered.

![Before "Add cases for Addr"](../assets/fill-switch-before.png)
![After "Add cases for Addr"](../assets/fill-switch-after.png)

And these screenshots illustrate the code action adding cases for each
value of the
[`html.TokenType`](https://pkg.go.dev/golang.org/x/net/html#TokenType)
enum type, which represents the various types of token from
which HTML documents are composed:

![Before "Add cases for Addr"](../assets/fill-switch-enum-before.png)
![After "Add cases for Addr"](../assets/fill-switch-enum-after.png)


<a name='refactor.rewrite.eliminateDotImport'></a>
### `refactor.rewrite.eliminateDotImport`: Eliminate dot import

When the cursor is on a dot import gopls can offer the "Eliminate dot import"
code action, which removes the dot from the import and qualifies uses of the
package throughout the file. This code action is offered only if
each use of the package can be qualified without collisions with existing names.

<a name='refactor.rewrite.addTags'></a>
### `refactor.rewrite.addTags`: Add struct tags

When the cursor is within a struct, this code action adds to each field a `json`
struct tag that specifies its JSON name, using lower case with underscores
(e.g. LinkTarget becomes link_target). For a highlighted selection, it only
adds tags on selected fields.

<a name='refactor.rewrite.removeTags'></a>
### `refactor.rewrite.removeTags`: Remove struct tags

When the cursor is within a struct, this code action clears struct tags on
all struct fields. For a highlighted selection, it removes tags from only
the selected fields.


================================================
FILE: gopls/doc/features/web.md
================================================
---
title: "Gopls: Web-based features"
---

The LSP
[`window.showDocument`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#window_showDocument) request
allows the server to instruct the client to open a file in the editor
or a web page in a browser. It is the basis for a number of gopls
features that report information about your program through a web
interface.

We recognize that a web interface is not ideal for everyone: some
users prefer a full-screen editor layout and dislike switching
windows; others may work in a text-only terminal without a window
system, perhaps over remote ssh or on the Linux console.
Unfortunately, the LSP lacks several natural kinds of extensibility,
including the ability for servers to define:

- queries that [generalize a References
  query](https://github.com/microsoft/language-server-protocol/issues/1911),
  displaying results using similar UI elements;
- commands that [produce a stream of
  text](https://github.com/joaotavora/eglot/discussions/1402), like a
  typical shell command or compiler, that the client can redirect to
  the editor's usual terminal-like UI element; or
- refactoring operations that, like Rename, [prompt the
  user](https://github.com/microsoft/language-server-protocol/issues/1164)
  for additional information.

The web-based UI can help fill these gaps until such time as the LSP
provides standard ways of implementing these features.

Gopls' web server listens on a `localhost` port. For security, all its
endpoints include a random string that serves as an authentication
token. The client, provided authenticated URLs by the server, will be
able to access your source code, but arbitrary processes running on
your machine will not.
Restarting the gopls process causes this secret to change, rendering
all existing previous URLs invalid; existing pages will display a banner
indicating that they have become disconnected.

TODO: combine the web server and the debug server; see https://go.dev/issue/68229.

Gopls supports two-way communication between the web browser and the
client editor. All of the web-based reports contain links to
declarations in your source code. Clicking on one of these links
causes gopls to send a `showDocument` request to your editor to open
the relevant source file at the appropriate line. This works even when
your source code has been modified but not saved.
(VS Code users: please upvote microsoft/vscode#208093 if you would
like your editor to raise its window when handling this event.)

<a name='doc'></a>
## `source.doc`: Browse package documentation

In any Go source file, a code action request returns a command to
"Browse package documentation". This command opens a browser window
showing the documentation for the current Go package, presented using
a similar design to https://pkg.go.dev.

This allows you to preview the documentation for your packages, even
internal ones that may be unpublished externally. Reloading the page
updates the documentation to reflect your changes. It is not necessary
to save modified Go source files.

<img title="Browse package documentation" src="../assets/browse-pkg-doc.png" width='80%'>

Clicking on the link for a package-level symbol or method, which in
`pkg.go.dev` would ordinarily take you to a source-code viewer such as
GitHub or Google Code Search, causes your editor to navigate to the
relevant source file and line.

Client support:
- **VS Code**: Use the "Source Action... > Browse documentation for package P" menu.
- **Emacs + eglot**: Use `M-x go-browse-doc` in [go-mode](https://github.com/dominikh/go-mode.el).
- **Vim + coc.nvim**: ??


<a name='freesymbols'></a>
## `source.freesymbols`: Browse free symbols

When studying code, either to understand it or to evaluate a different
organization or factoring, it is common to need to know what the
"inputs" are to a given chunk of code, either because you are
considering extracting it into its own function and want to know what
parameters it would take, or just to understand how one piece of a long
function relates to the preceding pieces.

If you select a chunk of code, and invoke the "Browse free symbols"
[code action](transformation.md#code-actions), your editor will
open a browser displaying a report on the free symbols of the
selection. A symbol is "free" if it is referenced from within the
selection but defined outside of it. In essence, these are the inputs
to the selected chunk.

<img title="Browse free symbols" src="../assets/browse-free-symbols.png" width='80%'>

The report classifies the symbols into imported, local, and
package-level symbols. The imported symbols are grouped by package,
and link to the documentation for the package, as described above.
Each of the remaining symbols is presented as a link that causes your
editor to navigate to its declaration.

TODO: explain dotted paths.

Client support:
- **VS Code**: Use the "Source Action... > Browse free symbols" menu.
- **Emacs + eglot**: Use `M-x go-browse-freesymbols` in [go-mode](https://github.com/dominikh/go-mode.el).
- **Vim + coc.nvim**: ??


<a name='assembly'></a>
## `source.assembly`: Browse assembly

When you're optimizing the performance of your code or investigating
an unexpected crash, it may sometimes be helpful to inspect the
assembly code produced by the compiler for a given Go function.

If you position the cursor or selection within a function f,
gopls offers the "Browse assembly for f" [code action](transformation.md#code-actions).
This opens a web-based listing of the assembly for the function, plus
any functions nested within it.

Each time you edit your source and reload the page, the current
package is recompiled and the listing is updated. It is not necessary
to save your modified files.

The compiler's target architecture is the same as the one gopls uses
when analyzing the file: typically, this is your machine's GOARCH, but
when viewing a file with a build tag, such as one named `foo_amd64.go`
or containing the comment `//go:build amd64`, the tags determine the
architecture.

Each instruction is displayed with a link that causes your editor to
navigate to the source line responsible for the instruction, according
to the debug information.

<img title="Browse assembly" src="../assets/browse-assembly.png" width="80%">

The example above shows the arm64 assembly listing of
[`time.NewTimer`](https://pkg.go.dev/time#NewTimer).
Observe that the indicated instruction links to a source location
inside a different function, `syncTimer`, because the compiler
inlined the call from `NewTimer` to `syncTimer`.

Browsing assembly is not yet supported for generic functions, package
initializers (`func init`), or functions in test packages.
(Contributions welcome!)

Client support:
- **VS Code**: Use the "Source Action... > Browse GOARCH assembly for f" menu.
- **Emacs + eglot**: Use `M-x go-browse-assembly` in [go-mode](https://github.com/dominikh/go-mode.el).
- **Vim + coc.nvim**: ??


<a name='splitpkg'></a>
## `source.splitPackage`: Split package into components

The web-based "Split package" tool can help you split a complex
package into two or more components, ensuring that the dependencies
among those components are acyclic.

Follow the instructions on the page to choose a set of named components,
assign each declaration to the most appropriate component, and then
visualize the dependencies between those components created by references
from one symbol to another.

The figure below shows the tool operating on the `fmt` package, which
could (in principle) be split into three subpackages, one for
formatting (`Printf` and friends), one for scanning (`Scanf`), and one
for their common dependencies.

<img title="Split package 'fmt'" src="../assets/splitpkg.png" width="55%">

(Try playing with the tool on this package: it's an instructive
exercise. The figure below shows the solution.)

<img title="Split package 'fmt'" src="../assets/splitpkg-deps.png" width="55%">

The tool does not currently perform the code transformation (moving
declarations to new packages, renaming symbols to export them as
needed), but we hope to add that in a future release.

Client support:
- **VS Code**: Use the "Source Action... > Split package P" menu.


================================================
FILE: gopls/doc/index.md
================================================
---
title: "Gopls: The language server for Go"
---
<!--
  This is the main landing page for gopls users.

  To preview locally edited markdown files, use:
    $ GOLANGORG_LOCAL_X_TOOLS=$(pwd) go run golang.org/x/website/cmd/golangorg@master &
    $ open http://localhost:6060/go.dev/gopls
-->

`gopls` (pronounced "Go please") is the official [language
server](https://langserver.org) for Go, developed by the Go team. It
provides a wide variety of [IDE features](features/) to any
[LSP](https://microsoft.github.io/language-server-protocol/)-compatible
editor.

<!--TODO(rfindley): Add gifs here.-->

You should not need to interact with `gopls` directly--it will be automatically
integrated into your editor. The specific features and settings vary slightly
by editor, so we recommend that you proceed to the
[documentation for your editor](#editors) below.
Also, the gopls documentation for each feature describes whether it is
supported in each client editor.

This documentation (https://go.dev/gopls) describes the most recent release of gopls.
To preview documentation for the release under development, visit https://tip.golang.org/gopls.

## Features

Gopls supports a wide range of standard LSP features for navigation,
completion, diagnostics, analysis, and refactoring, and a number of
additional features not found in other language servers.

See the [Index of features](features/) for complete
documentation on what Gopls can do for you.

## Editors

To get started with `gopls`, install an LSP plugin in your editor of choice.

<!-- TODO: be more consistent about editor (e.g. Emacs) vs. client (e.g. eglot). -->

* [Acme](https://github.com/9fans/acme-lsp/blob/master/README.md)
* [Atom](https://github.com/MordFustang21/ide-gopls/blob/master/README.md)
* [Emacs](editor/emacs.md)
* [Helix](editor/helix.md)
* [Lapce](https://github.com/lapce-community/lapce-go/blob/master/README.md)
* [Sublime Text](editor/sublime.md)
* [VS Code](https://github.com/golang/vscode-go/blob/master/README.md)
* [Vim or Neovim](editor/vim.md)
* [Zed](editor/zed.md)

If you use `gopls` with an editor that is not on this list, please send us a CL
[updating this documentation](contributing.md).

## Installation

To install the latest stable release of `gopls`, run the following command:

```sh
go install golang.org/x/tools/gopls@latest
```

Some editors, such as VS Code, will handle this step for you, and
ensure that Gopls is updated when a new stable version is released.

After updating, you may need to restart running Gopls processes to
observe the effect. Each client has its own way to restart the server.
(On a UNIX machine, you can use the command `killall gopls`.)

Learn more in the
[advanced installation instructions](advanced.md#installing-unreleased-versions).

## Releases

Gopls [releases](release/) follow [semantic versioning](http://semver.org), with
major changes and new features introduced only in new minor versions
(i.e. versions of the form `v*.N.0` for some N). Subsequent patch
releases contain only cherry-picked fixes or superficial updates.

In order to align with the
[Go release timeline](https://github.com/golang/go/wiki/Go-Release-Cycle#timeline),
we aim to release a new minor version of Gopls approximately every three
months, with patch releases approximately every month, according to the
following table:

| Month   | Version(s)   |
| ----    | -------      |
| Jan     | `v*.<N+0>.0` |
| Jan-Mar | `v*.<N+0>.*` |
| Apr     | `v*.<N+1>.0` |
| Apr-Jun | `v*.<N+1>.*` |
| Jul     | `v*.<N+2>.0` |
| Jul-Sep | `v*.<N+2>.*` |
| Oct     | `v*.<N+3>.0` |
| Oct-Dec | `v*.<N+3>.*` |

For more background on this policy, see https://go.dev/issue/55267.

## Setting up your workspace

`gopls` supports both Go module, multi-module and GOPATH modes. See the
[workspace documentation](workspace.md) for information on supported
workspace layouts.

## Configuration

You can configure `gopls` to change your editor experience or view additional
debugging information. Configuration options will be made available by your
editor, so see your [editor's instructions](#editors) for specific details. A
full list of `gopls` settings can be found in the [settings documentation](settings.md).

### Environment variables

`gopls` inherits your editor's environment, so be aware of any environment
variables you configure. Some editors, such as VS Code, allow users to
selectively override the values of some environment variables.

## Support policy

Gopls is maintained by engineers on the
[Go tools team](https://github.com/orgs/golang/teams/tools-team/members),
who actively monitor the
[Go](https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3Agopls)
and
[VS Code Go](https://github.com/golang/vscode-go/issues) issue trackers.

### Supported Go versions

`gopls` follows the
[Go Release Policy](https://go.dev/doc/devel/release#policy), meaning
that it officially supports only the two most recent major Go releases.

When using gopls, there are three versions to be aware of:
1. The _gopls build go version_: the version of Go used to build gopls.
2. The _go command version_: the version of the go list command executed by
   gopls to load information about your workspace.
3. The _language version_: the version in the go directive of the current
   file's enclosing go.mod file, which determines the file's Go language
   semantics.

Starting with the release of Go 1.23.0 and gopls@v0.17.0 in August 2024, we
will only support the most recent Go version as the _gopls build go version_.
However, due to the [forward compatibility](https://go.dev/blog/toolchain)
support added in Go 1.21, as long as Go 1.21 or later are used to install
gopls, any necessary toolchain upgrade will be handled automatically, just like
any other dependency.

Additionally, starting with gopls@v0.17.0, the _go command version_ will narrow
from 4 versions to 3. This is more consistent with the Go Release Policy.

Gopls supports **all** Go versions as its _language version_, by providing
compiler errors based on the language version and filtering available standard
library symbols based on the standard library APIs available at that Go
version.

Maintaining support for building gopls with legacy versions of Go caused
[significant friction](https://go.dev/issue/50825) for gopls maintainers and
held back other improvements. If you are unable to install a supported version
of Go on your system, you can still install an older version of gopls. The
following table shows the final gopls version that supports a given Go version.
Go releases more recent than those in the table can be used with any version of
gopls.

| Go Version  | Final gopls version with support (without warnings) |
| ----------- | --------------------------------------------------- |
| Go 1.12     | [gopls@v0.7.5](https://github.com/golang/tools/releases/tag/gopls%2Fv0.7.5) |
| Go 1.15     | [gopls@v0.9.5](https://github.com/golang/tools/releases/tag/gopls%2Fv0.9.5) |
| Go 1.17     | [gopls@v0.11.0](https://github.com/golang/tools/releases/tag/gopls%2Fv0.11.0) |
| Go 1.18     | [gopls@v0.14.2](https://github.com/golang/tools/releases/tag/gopls%2Fv0.14.2) |
| Go 1.20     | [gopls@v0.15.3](https://github.com/golang/tools/releases/tag/gopls%2Fv0.15.3) |

### Supported build systems

`gopls` currently only supports the `go` command, so if you are using
a different build system, `gopls` will not work well. Bazel is not officially
supported, but may be made to work with an appropriately configured
[go/packages driver](https://pkg.go.dev/golang.org/x/tools/go/packages#hdr-The_driver_protocol).
See [bazelbuild/rules_go#512](https://github.com/bazelbuild/rules_go/issues/512)
for more information.
You can follow [these instructions](https://github.com/bazelbuild/rules_go/wiki/Editor-setup)
to configure your `gopls` to work with Bazel.

### Troubleshooting

If you are having issues with `gopls`, please follow the steps described in the
[troubleshooting guide](troubleshooting.md).

## Additional information

* [Command-line interface](command-line.md)
* [Advanced topics](advanced.md)
* [Open issues](https://github.com/golang/go/issues?q=is%3Aissue+is%3Aopen+label%3Agopls)
* [Contributing to `gopls`](contributing.md)


================================================
FILE: gopls/doc/inlayHints.md
================================================
---
title: "Gopls: Inlay hints"
---

Inlay hints are helpful annotations that the editor can optionally
display in-line in the source code, such as the names of parameters in
a function call. This document describes the inlay hints available
from `gopls`.

<!-- This portion is generated by doc/generate from golang.AllInlayHints. -->
<!-- BEGIN Hints: DO NOT MANUALLY EDIT THIS SECTION -->
## **assignVariableTypes**

`"assignVariableTypes"` controls inlay hints for variable types in assign statements:
```go
	i/* int*/, j/* int*/ := 0, len(r)-1
```


**Disabled by default. Enable it by setting `"hints": {"assignVariableTypes": true}`.**

## **compositeLiteralFields**

`"compositeLiteralFields"` inlay hints for composite literal field names:
```go
	{/*in: */"Hello, world", /*want: */"dlrow ,olleH"}
```


**Disabled by default. Enable it by setting `"hints": {"compositeLiteralFields": true}`.**

## **compositeLiteralTypes**

`"compositeLiteralTypes"` controls inlay hints for composite literal types:
```go
	for _, c := range []struct {
		in, want string
	}{
		/*struct{ in string; want string }*/{"Hello, world", "dlrow ,olleH"},
	}
```


**Disabled by default. Enable it by setting `"hints": {"compositeLiteralTypes": true}`.**

## **constantValues**

`"constantValues"` controls inlay hints for constant values:
```go
	const (
		KindNone   Kind = iota/* = 0*/
		KindPrint/*  = 1*/
		KindPrintf/* = 2*/
		KindErrorf/* = 3*/
	)
```


**Disabled by default. Enable it by setting `"hints": {"constantValues": true}`.**

## **functionTypeParameters**

`"functionTypeParameters"` inlay hints for implicit type parameters on generic functions:
```go
	myFoo/*[int, string]*/(1, "hello")
```


**Disabled by default. Enable it by setting `"hints": {"functionTypeParameters": true}`.**

## **ignoredError**

`"ignoredError"` inlay hints for implicitly discarded errors:
```go
	f.Close() // ignore error
```
This check inserts an `// ignore error` hint following any
statement that is a function call whose error result is
implicitly ignored.

To suppress the hint, write an actual comment containing
"ignore error" following the call statement, or explicitly
assign the result to a blank variable. A handful of common
functions such as `fmt.Println` are excluded from the
check.


**Disabled by default. Enable it by setting `"hints": {"ignoredError": true}`.**

## **parameterNames**

`"parameterNames"` controls inlay hints for parameter names:
```go
	parseInt(/* str: */ "123", /* radix: */ 8)
```


**Disabled by default. Enable it by setting `"hints": {"parameterNames": true}`.**

## **rangeVariableTypes**

`"rangeVariableTypes"` controls inlay hints for variable types in range statements:
```go
	for k/* int*/, v/* string*/ := range []string{} {
		fmt.Println(k, v)
	}
```


**Disabled by default. Enable it by setting `"hints": {"rangeVariableTypes": true}`.**

<!-- END Hints: DO NOT MANUALLY EDIT THIS SECTION -->


================================================
FILE: gopls/doc/release/README
================================================
This directory contains the draft release notes for each upcoming release.

Be sure to update the file for the forthcoming release in the same CL
that you add new features or fix noteworthy bugs.

See https://github.com/golang/tools/releases for all past releases.

Tip: when reviewing edits to markdown files in Gerrit, to see the
rendered form, click the "Open in Code Search" link (magnifying glass
in blue square) then click "View in > gitiles" (shortcut: `v g`).


================================================
FILE: gopls/doc/release/v0.16.0.md
================================================
---
title: "Gopls release v0.16.0"
---

```
go install golang.org/x/tools/gopls@v0.16.2
```

This release includes several features and bug fixes, and is the first
version of gopls to support Go 1.23. To install it, run:

## New support policy; end of support for Go 1.19 and Go 1.20

**TL;DR: We are narrowing gopls' support window, but this is unlikely to
affect you as long as you use at least Go 1.21 to build gopls. This doesn't
affect gopls' support for the code you are writing.**

This is the last release of gopls that may be built with Go 1.19 or Go 1.20,
and also the last to support integrating with go command versions 1.19 and
1.20. If built or used with either of these Go versions, it will display
a message advising the user to upgrade.

When using gopls, there are three versions to be aware of:

1. The _gopls build go version_: the version of Go used to build gopls.
2. The _go command version_: the version of the go list command executed by
   gopls to load information about your workspace.
3. The _language version_: the version in the go directive of the current
   file's enclosing go.mod file, which determines the file's Go language
   semantics.

This gopls release, v0.16.0, is the final release to support Go 1.19 and Go
1.20 as the _gopls build go version_ or _go command version_. There is no
change to gopls' support for all _language versions_--in fact this support has
somewhat improved with the addition of the `stdversion` analyzer (see below).

Starting with gopls@v0.17.0, which will be released after Go 1.23.0 is released
in August, gopls will only support the latest version of Go as the
_gopls build go version_.
However, thanks to the [forward compatibility](https://go.dev/blog/toolchain)
added to Go 1.21, any necessary toolchain upgrade should be handled
automatically for users of Go 1.21 or later, just like any other dependency.
Additionally, we are reducing our _go command version_ support window from
4 versions to 3. Note that this means if you have at least Go 1.21 installed on
your system, you should still be able to `go install` and use gopls@v0.17.0.

We have no plans to ever change our _language version_ support: we expect that
gopls will always support developing programs that target _any_ Go version.

By focusing on building gopls with the latest Go version, we can significantly
reduce our maintenance burden and help improve the stability of future gopls
releases. See the newly updated
[support policy](https://github.com/golang/tools/tree/master/gopls#support-policy)
for details. Please comment on golang/go#65917 if
you have concerns about this change.

## Configuration changes

- The experimental `allowImplicitNetworkAccess` setting is deprecated (but not
  yet removed). Please comment on golang/go#66861 if you use this
  setting and would be impacted by its removal.

## New features

### Go 1.23 support

This version of gopls is the first to support the new language features of Go 1.23,
including
[range-over-func](https://go.dev/wiki/RangefuncExperiment) iterators
and support for the
[`godebug` directive](https://go.dev/ref/mod#go-mod-file-godebug)
in go.mod files.

### Integrated documentation viewer

Gopls now offers a "Browse documentation" code action that opens a
local web page displaying the generated documentation for Go packages
and symbols in a form similar to https://pkg.go.dev.
The package or symbol is chosen based on the current selection.

Use this feature to preview the marked-up documentation as you prepare API
changes, or to read the documentation for locally edited packages,
even ones that have not yet been saved. Reload the page after an edit
to see updated documentation.

<img title="Browse documentation for package" src="../assets/code-action-doc.png" width="80%">

As in `pkg.go.dev`, the heading for each symbol contains a link to the
source code of its declaration. In `pkg.go.dev`, these links would refer
to a source code page on a site such as GitHub or Google Code Search.
However, in gopls' internal viewer, clicking on one of these links will
cause your editor to navigate to the declaration.
(This feature requires that your LSP client honors the `showDocument` downcall.)

<img title="Symbol links navigate your editor to the declaration" src="../assets/browse-pkg-doc.png" width="80%">

Editor support:

- VS Code: use the "Source action > Browse documentation for func fmt.Println" menu item.
  Note: source links navigate the editor but don't yet raise the window yet.
  Please upvote microsoft/vscode#208093 and microsoft/vscode#207634 (temporarily closed).
- Emacs: requires eglot v1.17. Use `M-x go-browse-doc` from github.com/dominikh/go-mode.el.

The `linksInHover` setting now supports a new value, `"gopls"`,
that causes documentation links in the Markdown output
of the Hover operation to link to gopls' internal doc viewer.

### Browse free symbols

Gopls offers another web-based code action, "Browse free symbols",
which displays the free symbols referenced by the selected code.

A symbol is "free" if it is referenced within the selection but
declared outside of it. The free symbols that are variables are
approximately the set of parameters that would be needed if the block
were extracted into its own function.

Even when you don't intend to extract a block into a new function,
this information can help you to tell at a glance what names a block
of code depends on.

Each dotted path of identifiers (such as `file.Name.Pos`) is reported
as a separate item, so that you can see which parts of a complex
type are actually needed.

The free symbols of the body of a function may reveal that
only a small part (a single field of a struct, say) of one of the
function's parameters is used, allowing you to simplify and generalize
the function by choosing a different type for that parameter.

<img title="Browse free symbols" src="../assets/browse-free-symbols.png" width="80%">

Editor support:

- VS Code: use the `Source action > Browse free symbols` menu item.
- Emacs: requires eglot v1.17. Use `M-x go-browse-freesymbols` from github.com/dominikh/go-mode.el.

### Browse assembly

Gopls offers a third web-based code action, "Browse assembly for f",
which displays an assembly listing of the declaration of the function
f enclosing the selected code, plus any nested functions such as
function literals or deferred calls.

Gopls invokes the compiler to generate the report;
reloading the page updates the report.

The machine architecture is determined by the build
configuration that gopls selects for the current file.
This is usually the same as your machine's GOARCH unless you are
working in a file with `go:build` tags for a different architecture.

<img title="Browse assembly for function" src="../assets/browse-assembly.png" width="80%">

Gopls cannot yet display assembly for generic functions:
generic functions are not fully compiled until they are instantiated,
but any function declaration enclosing the selection cannot be an
instantiated generic function.

<!-- Clearly the ideal UX for generic functions is to use the function
     symbol under the cursor, e.g. Vector[string], rather than the
     enclosing function; but computing the name of the linker symbol
     remains a challenge. -->

Editor support:

- VS Code: use the "Source action > Browse assembly for f" menu item.
- Emacs: requires eglot v1.17. Use `M-x go-browse-assembly` from github.com/dominikh/go-mode.el.

### `unusedwrite` analyzer

The new
[unusedwrite](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedwrite)
analyzer reports assignments, often to fields of structs, that have no
effect because, for example, the struct is never used again:

```go
func scheme(host string) string {
	u := &url.URL{
		Host:   host, // "unused write to field Host" (no need to construct a URL)
		Scheme: "https:",
	}
	return u.Scheme
}
```

This is at best an indication that the code is unnecessarily complex
(for instance, some dead code could be removed), but often indicates a
bug, as in this example:

```go
type S struct { x int }

func (s S) set(x int) {
	s.x = x // "unused write to field x" (s should be a *S pointer)
}
```

### `stdversion` analyzer

The new
[`stdversion`](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdversion)
analyzer warns about the use of too-new standard library symbols based on the
version of the `go` directive in your `go.mod` file. This improves our support
for older _language versions_ (see above), even when gopls is built with
a recent Go version.

Consider the go.mod file and Go file below.
The declaration of `var `alias refers to a type, `types.Alias`,
introduced in go1.22, but the file belongs to a module that requires
only go1.21, so the analyzer reports a diagnostic:

```
module example.com
go 1.21
```

```go
package p

import "go/types"

var alias types.Alias // types.Alias requires go1.22 or later (module is go1.21)
```

When an individual file is build-tagged for a release of Go other than
than module's version, the analyzer will apply appropriate checks for
the file's version.

### Two more vet analyzers

The [framepointer](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/framepointer)
and [sigchanyzer](https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sigchanyzer)
analyzers have long been part of go vet's suite,
but had been overlooked in previous versions of gopls.

Henceforth, gopls will always include any analyzers run by vet.

### Hover shows size/offset info, and struct tags

Hovering over the identifier that declares a type or struct field now
displays the size information for the type:

<img title="struct size info" src="../assets/hover-size-struct.png">

and the offset information for the field:

<img title="field size/offset info" src="../assets/hover-size-field.png">

In addition, it reports the percentage of wasted space due to
suboptimal ordering of struct fields, if this figure is 20% or higher:

<img title="a struct with wasted space" src="../assets/hover-size-wasteful.png">

In the struct above, alignment rules require each of the two boolean
fields (1 byte) to occupy a complete word (8 bytes), leading to (7 + 7) / (3 \* 8) = 58% waste.
Placing the two booleans together would save a word.

This information may be helpful when making space optimizations to
your data structures, or when reading assembly code.

Also, hovering over a reference to a field with a struct tag now also
display the tag:

<img title="hover shows field tag" src="../assets/hover-field-tag.png">

### Hover and "Go to Definition" work on symbols in doc comments

Go 1.19 added support for [doc links](https://go.dev/doc/comment#links),
allowing the doc comment for one symbol to reference another.

Gopls' Hover and Definition operations now treat these links just
like identifiers, so hovering over one will display information about
the symbol:

<img title="hover shows field tag" src="../assets/hover-doclink.png">

Similarly, "Go to definition" will navigate to its declaration.
Thanks to @rogeryk for contributing this feature.

## Bugs fixed

## Thank you to our contributors!

@guodongli-google for the `unusedwrite` analyzer.
TODO: they're a xoogler; is there a more current GH account?

@rogeryk


================================================
FILE: gopls/doc/release/v0.17.0.md
================================================
---
title: "Gopls release v0.17.0"
---

<!-- TODO: update this instruction once v0.17.0 is released

    Also, tweak the img URLs when publishing to GitHub Releases.
-->

```
go install golang.org/x/tools/gopls@v0.17.0-pre.4
```

## New support policies

With this release, we are narrowing our official support window to align with
the [Go support policy](https://go.dev/doc/devel/release#policy). This will
reduce the considerable costs to us of testing against older Go versions,
allowing us to spend more time fixing bugs and adding features that benefit the
majority of gopls users who run recent versions of Go.

This narrowing is occurring in two dimensions: **build compatibility** refers to
the versions of the Go toolchain that can be used to build gopls, and **go
command compatibility** refers to the versions of the `go` command that can be
used by gopls to list information about packages and modules in your workspace.

### Build compatibility: the most recent major Go version

As described in the [v0.16.0 release
notes](https://github.com/golang/tools/releases/tag/gopls%2Fv0.16.0), building the
latest version of gopls will now require the latest major version of the Go
toolchain. Therefore this release (gopls@v0.17.0) must be built with Go 1.23.0
or later. Thanks to [automatic toolchain
upgrades](https://go.dev/blog/toolchain), if your system Go version is at least
Go 1.21.0 and you have `GOTOOLCHAIN=auto` set (the default), the `go` command
will automatically download the new Go toolchain as needed, similar to
upgrading a module dependency.

### Go command compatibility: the 2 most recent major Go versions

The gopls@v0.17.x releases will be the final versions of gopls to nominally
support integrating with more than the 2 most recent Go releases. In the past,
we implied "best effort" support for up to 4 versions, though in practice we
did not have resources to fix bugs that were present only with older Go
versions. With gopls@v0.17.0, we narrowed this best effort support to 3
versions, primarily because users need at least Go 1.21 to benefit from
automatic toolchain upgrades (see above).

Starting with gopls@v0.18.0, we will officially support integrating with only
the 2 most recent major versions of the `go` command. This is consistent with
the Go support policy. See golang/go#69321 (or [this
comment](https://github.com/golang/go/issues/69321#issuecomment-2344996677)
specifically) for details.

We won't prevent gopls from being used with older Go versions (just as we
don't disallow integration with arbitrary
[`go/packages`](https://pkg.go.dev/golang.org/x/tools/go/packages) drivers),
but we won't run integration tests against older Go versions, and won't fix
bugs that are only present when used with old Go versions.

## Configuration Changes

- The `fieldalignment` analyzer, previously disabled by default, has
  been removed: it is redundant with the hover size/offset information
  displayed by v0.16.0 and its diagnostics were confusing.
- The `undeclaredname` analyzer has been replaced with an ordinary code action.
- The kind (identifiers) of all of gopls' code actions have changed
  to use more specific hierarchical names. For example, "Inline call"
  has changed from `refactor.inline` to `refactor.inline.call`.
  This allows clients to request particular code actions more precisely.
  The user manual now includes the identifier in the documentation for each code action.
- The experimental `allowImplicitNetworkAccess` setting is removed, following
  its deprecation in gopls@v0.16.0. See golang/go#66861 for details.

## New features

### Refactoring

This release contains a number of new features related to refactoring.
Additionally, it fixes [many
bugs](https://github.com/golang/go/issues?q=is%3Aissue+milestone%3Agopls%2Fv0.17.0+label%3ARefactoring+is%3Aclosed)
in existing refactoring operations, primarily related to **extract**, and **inline**.

These improvements move us toward a longer term goal of offering a more robust
and complete set of refactoring tools. We still have [much to
do](https://github.com/golang/go/issues?q=is%3Aissue+label%3Agopls+label%3ARefactoring+is%3Aopen+),
and this effort will continue into 2025.

#### Move parameter refactorings

Gopls now offers code actions to move function and method parameters left or
right in the function signature, updating all callers.

Unfortunately, there is no native LSP operation that provides a good user
interface for arbitrary "change signature" refactoring. We plan to build such
an interface within VS Code. In the short term, we have made it possible to
express more complicated parameter transformations by invoking 'rename' on the
'func' keyword. This user interface is a temporary stop-gap until a better
mechanism is available for LSP commands that enable client-side dialogs.

#### Extract declarations to new file

Gopls now offers another code action,
"Extract declarations to new file" (`refactor.extract.toNewFile`),
which moves selected code sections to a newly created file within the
same package. The created filename is chosen as the first {function, type,
const, var} name encountered. In addition, import declarations are added or
removed as needed.

The user can invoke this code action by selecting a function name, the keywords
`func`, `const`, `var`, `type`, or by placing the caret on them without selecting,
or by selecting a whole declaration or multiple declarations.

In order to avoid ambiguity and surprise about what to extract, some kinds
of partial selection of a declaration cannot invoke this code action.

#### Extract constant

When the selection is a constant expression, gopls now offers "Extract
constant" instead of "Extract variable", and generates a `const`
declaration instead of a local variable.

Also, extraction of a constant or variable now works at top-level,
outside of any function.

#### Generate missing method from function call

When you attempt to call a method on a type that lacks that method, the
compiler will report an error like “type T has no field or method f”. Gopls now
offers a new code action, “Declare missing method of T.f”, where T is the
concrete type and f is the undefined method. The stub method's signature is
inferred from the context of the call.

#### Generate a test for a function or method

If the selected chunk of code is part of a function or method declaration F,
gopls will offer the "Add test for F" code action, which adds a new test for the
selected function in the corresponding `_test.go` file. The generated test takes
into account its signature, including input parameters and results.

Since this feature is implemented by the server (gopls), it is compatible with
all LSP-compliant editors. VS Code users may continue to use the client-side
`Go: Generate Unit Tests For file/function/package` command, which runs the
[gotests](https://github.com/cweill/gotests) tool.

### Initial support for pull diagnostics

When initialized with the option `"pullDiagnostics": true`, gopls will advertise support for the
`textDocument.diagnostic`
[client capability](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_pullDiagnostics),
which allows editors to request diagnostics directly from gopls using a
`textDocument/diagnostic` request, rather than wait for a
`textDocument/publishDiagnostics` notification. This feature is off by default
until the feature set of pull diagnostics is comparable to push diagnostics.

### Hover improvements

The `textDocument/hover` response has slightly tweaked markdown rendering, and
includes the following additional information:

- Hovering over a standard library symbol now displays information about the
  first Go release containing the symbol. For example, hovering over
  `errors.As` shows "Added in go1.13".
- Hovering over the package name in a package declaration includes additional
  package metadata.

### Semantic token modifiers of top-level constructor of types

The semantic tokens response now includes additional modifiers for the top-level
constructor of the type of each symbol:
`interface`, `struct`, `signature`, `pointer`, `array`, `map`, `slice`, `chan`, `string`, `number`, `bool`, and `invalid`.
Editors may use this for syntax coloring.

### SignatureHelp for ident and values.

Now, function signature help can be used on any identifier with a function
signature, not just within the parentheses of a function being called.

### Jump to assembly definition

A Definition query on a reference to a function jumps to the
function's Go `func` declaration. If the function is implemented in C
or assembly, the function has no body. Executing a second Definition
query (while already at the Go declaration) will navigate you to the
assembly implementation.

### `yield` analyzer

The new `yield` analyzer detects mistakes using the `yield` function
in a Go 1.23 iterator, such as failure to check its boolean result and
break out of a loop.

### `waitgroup` analyzer

The new `waitgroup` analyzer detects calls to the `Add` method of
`sync.WaitGroup` that are (mistakenly) made within the new goroutine,
causing `Add` to race with `Wait`.
(This check is equivalent to
[staticcheck's SA2000](https://staticcheck.dev/docs/checks#SA2000),
but is enabled by default.)


================================================
FILE: gopls/doc/release/v0.18.0.md
================================================
---
title: "Gopls release v0.18.0"
---

## Configuration Changes

<!-- TODO(rfindley): add links to relevant settings documentation -->

- The experimental `Structured` value for the `hoverKind` option is no longer
  supported.

- The `gc_details` code lens has been deleted. (It was previously disabled by
  default.) This functionality is now available through the
  `toggleCompilerOptDetails` code action (documented below), as code
  actions are better supported than code lenses across a range of clients.

  VS Code's special "Go: Toggle GC details" command continues to work.

- The experimental `semanticTokenTypes` and `semanticTokenModifiers` options
  allow selectively disabling certain types of tokens or token modifiers in
  `textDocument/semanticTokens` responses.

  These options supersede the `noSemanticString` and `noSemanticTokenNumber`
  options, which are now deprecated. Users can instead set
  `"semanticTokenTypes": {"string": false, "number": false}` to achieve the
  same result. For now, gopls still honors `noSemanticTokenString` and
  `noSemanticToken`, but will stop supporting them in a future release.

- The new `workspaceFiles` option allows configuring glob patterns matching
  files that define the logical build of the workspace. This option is only
  needed in environments that use a custom golang.org/x/tools/go/packages
  driver.

## New features

### "{Show,Hide} compiler optimization details" code action

This code action, accessible through the "Source Action" menu in VS
Code, toggles a per-directory flag that causes Go compiler optimization
details to be reported as diagnostics. For example, it indicates which
variables escape to the heap, and which array accesses require bounds
checks.

TODO: add links to the complete manual for each item.

### New `modernize` analyzer

Gopls now reports when code could be simplified or clarified by
using more modern features of Go, and provides a quick fix to apply
the change.

For example, a conditional assignment using an if/else statement may
be replaced by a call to the `min` or `max` built-in functions added
in Go 1.18.

Use this command to apply modernization fixes en masse:
```
$ go run golang.org/x/tools/go/analysis/passes/modernize/cmd/modernize@latest -fix ./...
```

### New `unusedfunc` analyzer

Gopls now reports unused functions and methods, giving you near
real-time feedback about dead code that may be safely deleted.
Because the analysis is local to each package, only unexported
functions and methods are candidates.
(For a more precise analysis that may report unused exported
functions too, use the `golang.org/x/tools/cmd/deadcode` command.)

### New `hostport` analyzer

With the growing use of IPv6, forming a "host:port" string using
`fmt.Sprintf("%s:%d")` is no longer appropriate because host names may
contain colons. Gopls now reports places where a string constructed in
this fashion (or with `%s` for the port) is passed to `net.Dial` or a
related function, and offers a fix to use `net.JoinHostPort`
instead.

### Other analyzer changes

- The `unusedvariable` quickfix is now on by default.
- The `unusedparams` analyzer no longer reports finding for generated files.

### New `gofix` analyzer

Gopls now reports when a function call or a use of a constant should be inlined.
These diagnostics and the associated code actions are triggered by "//go:fix inline"
directives at the function and constant definitions.
(See [the go:fix proposal](https://go.dev/issue/32816).)

For example, consider a package `intmath` with a function `Square(int) int`.
Later the more general `Pow(int, int) int` is introduced, and `Square` is deprecated
in favor of calling `Pow` with a second argument of 2. The author of `intmath`
can write this:
```
//go:fix inline
func Square(x int) int { return Pow(x, 2) }
```
If gopls sees a call to `intmath.Square` in your code, it will suggest inlining
it, and will offer a code action to do so.

The same feature works for constants.
With a constant definition like this:
```
//go:fix inline
const Ptr = Pointer
```
gopls will suggest replacing `Ptr` in your code with `Pointer`.

Use this command to apply such fixes en masse:

```
$ go run golang.org/x/tools/go/analysis/passes/inline/cmd/inline@latest -fix ./...
```

### "Implementations" supports generics

At long last, the "Go to Implementations" feature now fully supports
generic types and functions (#59224).

For example, invoking the feature on the interface method `Stack.Push`
below will report the concrete method `C[T].Push`, and vice versa.

```go
package p

type Stack[T any] interface {
	Push(T) error
	Pop() (T, bool)
}

type C[T any] struct{}

func (C[T]) Push(t T) error { ... }
func (C[T]) Pop() (T, bool) { ... }

var _ Stack[int] = C[int]{}
```

### Extract all occurrences of the same expression under selection

When you have multiple instances of the same expression in a function,
you can use this code action to extract it into a variable.
All occurrences of the expression will be replaced with a reference to the new variable.

### Improvements to "Definition"

The Definition query now supports additional locations:

- When invoked on a return statement, it reports the location
  of the function's result variables.
- When invoked on a break, goto, or continue statement, it reports
  the location of the label, the closing brace of the relevant
  block statement, or the start of the relevant loop, respectively.

### Improvements to "Hover"

When invoked on a return statement, hover reports the types of
the function's result variables.

### UX improvements to format strings

#### "DocumentHighlight"

When your cursor is inside a printf-like function, gopls now highlights the relationship between
formatting verbs and arguments as visual cues to differentiate how operands are used in the format string.

```go
fmt.Printf("Hello %s, you scored %d", name, score)
```

If the cursor is either on `%s` or `name`, gopls will highlight `%s` as a write operation,
and `name` as a read operation.

#### "SemanticHighlight"

Similar to the improvements to DocumentHighlight, gopls also reports formatting verbs
as "format" modifier for token type "string" to better distinguish them with other parts of the format string.

```go
fmt.Printf("Hello %s, you scored %d", name, score)
```

`%s` and `%d` will have token type "string" and modifier "format".


================================================
FILE: gopls/doc/release/v0.19.0.md
================================================
---
title: "Gopls release v0.19.0"
---

## Configuration Changes

- The `gopls check` subcommand now accepts a `-severity` flag to set a minimum
  severity for the diagnostics it reports. By default, the minimum severity
  is "warning", so `gopls check` may report fewer diagnostics than before. Set
  `-severity=hint` to reproduce the previous behavior.

## Navigation features

### "Implementations" supports signature types (within same package)

<!-- golang/go#56572 -->

The Implementations query reports the correspondence between abstract
and concrete types and their methods based on their method sets.
Now, it also reports the correspondence between function types,
dynamic function calls, and function definitions, based on their signatures.

To use it, invoke an Implementations query on the `func` token of the
definition of a named function, named method, or function literal.
Gopls reports the set of function signature types that abstract this
function, and the set of dynamic calls through values of such types.

Conversely, an Implementations query on the `func` token of a
signature type, or on the `(` paren of a dynamic function call,
reports the set of concrete functions that the signature abstracts
or that the call dispatches to.

Since a type may be both a function type and a named type with methods
(for example, `http.HandlerFunc`), it may participate in both kinds of
Implements queries (method-sets and function signatures).
Queries using method-sets should be invoked on the type or method name,
and queries using signatures should be invoked on a `func` or `(` token.

Only the local (same-package) algorithm is currently supported.
(https://go.dev/issue/56572 tracks the global algorithm.)

### "Go to Implementation" reports interface-to-interface relations

<!-- golang/go#68641 -->

The "Go to Implementation" operation now reports relationships between
interfaces. Gopls now uses the concreteness of the query type to
determine whether a query is "downwards" (from an interface to the
types that implement it) or "upwards" (from a concrete type to the
interfaces to which it may be assigned). So, for example:

- `implementation(io.Reader)` subinterfaces such as `io.ReadCloser`,
  and concrete implementations such as `*os.File`.

- `implementation(os.File)` includes only interfaces, such as
  `io.Reader` and `io.ReadCloser`.

To request an "upwards" query starting from an interface, for example
to find the superinterfaces of `io.ReadCloser`, use the Type Hierarchy
feature described below.
(See https://github.com/microsoft/language-server-protocol/issues/2037.)

### Support for Type Hierarchy

<!-- golang/go#72142 -->

Gopls now implements the three LSP methods related to the Type
Hierarchy viewer: `textDocument/prepareTypeHierarchy`,
`typeHierarchy/supertypes`, `typeHierarchy/subtypes`.

In VS Code, select "Show Type Hierarchy" from the context menu
to see a tree widget displaying all the supertypes or subtypes
of the selected named type.

<img title="Type Hierarchy: supertypes of net.Conn" src="../assets/supertypes.png" width="400">

<img title="Type Hierarchy: subtypes of io.Writer" src="../assets/subtypes.png" width="400">


## Editing features

### Completion: auto-complete package clause for new Go files

Gopls now automatically adds the appropriate `package` clause to newly created Go files,
so that you can immediately get started writing the interesting part.

It requires client support for `workspace/didCreateFiles`

### New GOMODCACHE index for faster Organize Imports and unimported completions

By default, gopls now builds and maintains a persistent index of
packages in the module cache (GOMODCACHE). The operations of Organize
Imports and completion of symbols from unimported packages are an
order of magnitude faster.

To revert to the old behavior, set the `importsSource` option (whose
new default is `"gopls"`) to `"goimports"`. Users who don't want the
module cache used at all for imports or completions can change the
option to "off".

## Analysis features

### Most `staticcheck` analyzers are enabled by default

Slightly more than half of the analyzers in the
[Staticcheck](https://staticcheck.dev/docs/checks) suite are now
enabled by default. This subset has been chosen for precision and
efficiency.

Previously, Staticcheck analyzers (all of them) would be run only if
the experimental `staticcheck` boolean option was set to `true`. This
value continues to enable the complete set, and a value of `false`
continues to disable the complete set. Leaving the option unspecified
enables the preferred subset of analyzers.

Staticcheck analyzers, like all other analyzers, can be explicitly
enabled or disabled using the `analyzers` configuration setting; this
setting now takes precedence over the `staticcheck` setting, so,
regardless of what value of `staticcheck` you use (true/false/unset),
you can make adjustments to your preferred set of analyzers.

### `recursiveiter`: "inefficient recursive iterator"

A common pitfall when writing a function that returns an iterator
(`iter.Seq`) for a recursive data type is to recursively call the
function from its own implementation, leading to a stack of nested
coroutines, which is inefficient.

The new `recursiveiter` analyzer detects such mistakes; see
[its documentation](https://golang.org/x/tools/gopls/internal/analysis/recursiveiter)
for details, including tips on how to define simple and efficient
recursive iterators.

### `maprange`: "inefficient range over maps.Keys/Values"

The new `maprange` analyzer detects redundant calls to `maps.Keys` or
`maps.Values` as the operand of a range loop; maps can of course be
ranged over directly. See
[its documentation](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/maprange)
for details).

## Code transformation features

### Rename method receivers

<!-- golang/go#41892 -->

The Rename operation, when applied to the declaration of a method
receiver, now also attempts to rename the receivers of all other
methods associated with the same named type. Each other receiver that
cannot be fully renamed is quietly skipped.

Renaming a _use_ of a method receiver continues to affect only that
variable.

```go
type Counter struct { x int }

                 Rename here to affect only this method
                          ↓
func (c *Counter) Inc() { c.x++ }
func (c *Counter) Dec() { c.x++ }
      ↑
  Rename here to affect all methods
```

### "Eliminate dot import" code action

<!-- golang/go#70319 -->

This code action, available on a dotted import, will offer to replace
the import with a regular one and qualify each use of the package
with its name.

### Add/remove tags from struct fields

Gopls now provides two new code actions, available on an entire struct
or some of its fields, that allow you to add and remove struct tags.
It adds only 'json' tags with a snakecase naming format, or clears all
tags within the selection.

Add tags example:
```go
type Info struct {
    LinkTarget string        ->      LinkTarget string `json:"link_target"`
    ...
}
```

### Inline local variable

<!-- golang/go#70085 -->

The new `refactor.inline.variable` code action replaces a reference to
a local variable by that variable's initializer expression. For
example, when applied to `s` in `println(s)`:

```go
func f(x int) {
	s := fmt.Sprintf("+%d", x)
	println(s)
}
```
it transforms the code to:
```go
func f(x int) {
	s := fmt.Sprintf("+%d", x)
	println(fmt.Sprintf("+%d", x))
}
```

Only a single reference is replaced; issue https://go.dev/issue/70085
tracks the feature to "inline all" uses of the variable and eliminate
it.


## Thank you to our contributors!

[@acehinnnqru](https://github.com/acehinnnqru)
[@adonovan](https://github.com/adonovan)
[@albfan](https://github.com/albfan)
[@aarzilli](https://github.com/aarzilli)
[@ashurbekovz](https://github.com/ashurbekovz)
[@cuonglm](https://github.com/cuonglm)
[@dmitshur](https://github.com/dmitshur)
[@neild](https://github.com/neild)
[@egonelbre](https://github.com/egonelbre)
[@shashank](https://github.com/shashank)
[priyadarshi](https://github.compriyadarshi)
[@firelizzard18](https://github.com/firelizzard18)
[@gopherbot](https://github.com/gopherbot)
[@h9jiang](https://github.com/h9jiang)
[@cuishuang](https://github.com/cuishuang)
[@jakebailey](https://github.com/jakebailey)
[@jba](https://github.com/jba)
[@madelinekalil](https://github.com/madelinekalil)
[@karamaru](https://github.com/karamaru)
[alpha](https://github.comalpha)
[@danztran](https://github.com/danztran)
[@nsrip](https://github.com/nsrip)
[dd](https://github.comdd)
[@pjweinb](https://github.com/pjweinb)
[@findleyr](https://github.com/findleyr)
[@samthanawalla](https://github.com/samthanawalla)
[@seankhliao](https://github.com/seankhliao)
[@tklauser](https://github.com/tklauser)
[@vikblom](https://github.com/vikblom)
[@kwjw](https://github.com/kwjw)
[@xieyuschen](https://github.com/xieyuschen)


================================================
FILE: gopls/doc/release/v0.20.0.md
================================================
---
title: "Gopls release v0.20.0"
---

This release contains a new experimental Model Context Protocol (MCP)
server for gopls, which may be used to integrate a subset of gopls'
features in AI-assisted environments.

Gopls' documentation is now available on the Go project's website at
https://go.dev/gopls. (This link reflects the latest gopls release;
use https://tip.golang.org/gopls to see docs for the latest commit.)
Unlike Markdown files in GitHub, these pages are crawled by Google's
web search index.

## Configuration changes

This release enables by default the new persistent index of packages
in the module cache. This was first attempted in [v0.19](./v0.19.0.md) but reverted
due to problems that have since been fixed.

## Web-based features

### "Split package" tool

The `source.splitPackage` code action opens a web-based tool that
helps you split a package into two or more components whose
dependencies are acyclic.

To use it, name a set of components, assign each declaration to a
component, then visualize the dependencies among the components
(including whether they form a cycle).
Refresh the page each time you edit your code to see the latest
information.

<p align="center"><img title="Split package 'fmt'" src="../assets/splitpkg.png" width="600"></p>

The tool makes it easy to iterate over potential decompositions
until you find one you are happy with. A future version of
the tool will automate the code transformation, but for now
you must do that step by hand.


## Editing features

### Model Context Protocol server

Gopls now includes an experimental built-in server for the Model Context
Protocol (MCP), allowing it to expose a subset of its functionality to
AI assistants in the form of MCP tools.

See the [documentation](../features/mcp.md) for more information.

**Caveats:** This is a brand new mode of operation for gopls, and so we're
still experimenting with the best set of tools and instructions to provide.
Please let us know how well it works for you. Also, please be aware that
allowing LLMs to execute operations in your workspace entails additional
security considerations, as discussed in the documentation above.

## Analysis features

### `ignoredError` inlay hint

The new `ignoredError` inlay hint helps catch mistakenly discarded
errors. It inserts an `// ignore error` hint following any statement
that is a function call whose error result is implicitly ignored. For
example, this code:

```go
f.Close()
```
will appear as:
```go
f.Close() // ignore error
```

To suppress the hint, write an actual comment containing `ignore
error` following the call statement, or explicitly assign the result
to a blank `_` variable. A handful of common functions such as
`fmt.Println` are excluded from the check.

Enable it using this configuration: `{"hints": {"ignoredError": true}}`.

### `unusedfunc` reports unused `type`, `var`, and `const` declarations too

<!-- golang/go#40862 -->

The
[unusedfunc](https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedfunc/)
analyzer now reports any unexported types, variables, and constants
that are unreferenced within their declaring package.
(The problem of unreferenced exported symbols can't be expressed in
the analysis framework since it depends on the entire workspace.)

## Code transformation features

<!-- golang/go#45199 -->
The Rename operation now allows you to rename an embedded field, such
as T in `struct{ T }`, so long as the operation is requested at the
field declaration (T). Both the field and its type will be renamed.


================================================
FILE: gopls/doc/release/v0.21.0.md
================================================
---
title: "Gopls release v0.21.0 (expected Dec 2025)"
---

## Configuration changes

- The new `newGoFileHeader` option allows toggling automatic insertion of the copyright comment
  and package declaration in a newly created Go file.

- The default value of the `codelenses` setting now includes
  `run_govulncheck: true`, causing gopls to offer a "Run govulncheck"
  command associated with the `module` declaration in a go.mod file.

- The experimental `vulncheck` setting now supports the enum value
  `"Prompt"`, meaning that vulncheck can be triggered via a prompt;
  this is now the default.

- The new, experimental `renameMovesSubpackages` setting determines
  whether a rename package operation applies to subdirectories; see
  below for details.

## Navigational features:

Hover can now report information about selected subexpressions (#69058).
For example, selecting the region indicated below:

	 x[i].f()
	 ~~~~

will report information about the subexpression `x[i]`, such as its
type, constant value (if appropriate), and methods.
Previously, Hover would report only about `x`, `i`, or `f`.

This feature requires the client to supply an extra field in the
`textDocumentPositionParams` part of its LSP `textDocument/hover`
request: the standard struct has a single `position` of type
`Position`, but gopls can also handle a `range` field of type
`Range` that specifies the extent of the text selection.
(If supplied, it must enclose the `position`.)

The VS Code code extension already populates this field. We plan to
use it across various requests, and to lobby for its adoption by the
LSP standard.

Other features in brief:

- Definition now works for fields in doc links in comments (#75038).
- Hover adds navigation to doc links in hovers (golang/vscode-go#3827).
- Hover now reports information (size, etc) about embedded fields, not just their types (#75975).
- Folding Range now displays closing parens (#75229) and more ranges (#73735).

## Analysis features

### `reflecttypefor` analyzer

<!-- golang/go#60088 -->

The new `reflecttypefor` analyzer modernizes calls to `reflect.TypeOf`
to use `reflect.TypeFor` when the runtime type is known at compile
time. For example:

	reflect.TypeOf(uint32(0))

becomes:

	reflect.TypeFor[uint32]()

### `newexpr` analyzer

<!-- golang/go#45624 -->

The `newexpr` analyzer finds declarations of and calls to functions
of this form:
```go
func varOf(x int) *int { return &x }

use(varOf(123))
```
modernizing them when appropriate to use the `new(expr)` feature of Go 1.26:
```go
//go:fix inline
func varOf(x int) *int { return new(x) }

use(new(123))
```

Such wrapper functions are widely used in serialization packages,
for instance the proto.{Int64,String,Bool} helpers used with
protobufs.

### `stditerators` analyzer

<!-- golang/go#75693 -->

The `stditerators` analyzer replaces loops of this form,

      for i := 0; i < x.Len(); i++ {
          use(x.At(i))
      }

or their "range x.Len()" equivalent, by

      for elem := range x.All() {
          use(elem)
      }

for various types in the standard library that now offer a
modern iterator-based API.

### `stringscut` analyzer

<!-- golang/go#71369 -->

The `stringscut` analyzer modernizes various patterns of use of
`strings.Index` such as:

	i := strings.Index(s, sep)
	if i >= 0 {
		use(s[i:])
	}

by a call to `strings.Cut`, introduced in Go 1.25:

	before, after, ok := strings.Cut(s, sep)
	if ok {
		use(after)
	}

### `plusbuild` analyzer

<!-- golang/go#73605 -->

The `plusbuild` analyzer removes old-style `+build` build-tag comments
when they are redundant with the newer form:

	//go:build linux
	// +build linux

### `errorsastype` analyzer

<!-- golang/go#75692 -->

The `errorsastype` analyzer replaces calls to `errors.As`:

	var myErr *MyError
	if errors.As(err, &myErr) { ... }

by the more modern `errors.AsType`, when the type is known statically:

	if myErr, ok := errors.AsType[*MyError](err) { ... }


### `unsafefuncs` analyzer

<!-- golang/go#76648 -->

The `unsafefuncs` analyzer replaces arithmetic such as:

	unsafe.Pointer(uintptr(ptr) + uintptr(n))

where ptr is an unsafe.Pointer, by calls to `unsafe.Add`, added in Go 1.17.

	unsafe.Add(ptr, n)

### Miscellaneous

- The `minmax` modernizer now removes user-defined min/max functions when they are redundant.
- The `stringscutprefix` modernizer now handles `strings.CutSuffix` too. <!-- #75205 -->
- The `yield` and `nilness` analyzers handle control-flow booleans more precisely. <!-- #74136, #75924 -->
- The `printf` analyzer now checks calls to local anonymous printf-wrapper functions too.
- The `staticcheck` suite has been updated to v0.7.

## Code transformation features

### Generalized package renaming

<!-- #57171 #75812 -->

The Rename operation, invoked on a `package p` declaration, now
prompts you to edit the entire package path. This allows you to choose
not just a new name for the package, but a new directory anywhere
within the same module. For example, you can rename `example.com/foo`
to `example.com/internal/bar`, and the tool will move files and update
imports as needed.

By default, subpackages are no longer moved with the renamed package.
Enable the new (experimental) `renameMovesSubpackages` setting if you
want subpackages to move too. (In due course, we will add LSP support
for dialogs so that the server can query the user's intent
interactively.)

This feature requires client support for the LSP
[`textDocument/prepareRename`](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_prepareRename) operation.

### Renaming from a doc link

<!-- golang/go#42301 -->
The Rename operation now treats [doc links](https://tip.golang.org/doc/comment#doclinks)
like identifiers, so you can initiate a renaming from a doc link.

## Model context protocol (MCP) features

The MCP server now supports the `go_rename_symbol` tool, which permits
an agent to rename a symbol based on its name (e.g. `fmt.Println` or
`bytes.Buffer.WriteString`). The tool uses the symbol index to resolve
the name to a declaration and then initiates a renaming.

The server also supports the `gopls.vulncheck` tool, allowing agents
to scan packages for security vulnerabilities.

## Closed issues

https://github.com/golang/go/milestone/399?closed=1



================================================
FILE: gopls/doc/release/v0.22.0.md
================================================
---
title: "Gopls release v0.22.0 (forthcoming)"
---

## Configuration changes
## Navigation features
<!-- golang/go#75810 -->

- Asking for references while hovering over the name of a required module in a `go.mod` file
  will show all the imports of that module in the main module (the go.mod's module).
## Web-based features
## Editing features
## Analysis features

### `atomictypes` analyzer
<!-- golang/go#77352 -->

The new atomictypes analyzer suggests replacing the primitive `sync/atomic` functions with
the strongly typed atomic wrapper types introduced in Go1.19 (e.g.
atomic.Int32). It refactors declarations like `var x int32` to
`var x atomic.Int32` and updates all corresponding call sites from
`atomic.AddInt32(&x, 1)` to method calls like `x.Add(1)`.

### `fieldassignment` analyzer
<!-- golang/go#76237 -->
The fieldassignment analyzer, which reports diagnostics about memory layout and
was disabled in v0.17.0, has been restored. It is disabled by default.


### `writestring` analyzer
<!-- golang/go#77369 -->

The new writestring analyzer detects inefficient string concatenation in uses of WriteString,
of the form WriteString(a+b), and offers to replace them with WriteString(a); WriteString(b).

### `waitgroup` modernizer renamed to `waitgroupgo`
<!-- golang/go#77560 -->

Previously there were two analyzers named `waitgroup`: an analyzer that checks
for misuses of `sync.WaitGroup`, and a modernizer that simplifies goroutine
management with `sync.WaitGroup`. We have renamed the modernizer to `waitgroupgo`.

## Code transformation features

### $feature

https://go.dev/issue#xxxxx


================================================
FILE: gopls/doc/settings.md
================================================
---
title: "Gopls: Settings"
---

This document describes gopls' configuration settings.

Gopls settings are defined by a JSON object whose valid fields are
described below. These fields are gopls-specific, and generic LSP
clients have no knowledge of them.

Different clients present configuration settings in their user
interfaces in a wide variety of ways.
For example, some expect the user to edit the raw JSON object while
others use a data structure in the editor's configuration language;
still others (such as VS Code) have a graphical configuration system.
Be sure to consult the documentation for how to express configuration
settings in your client.
Some clients also permit settings to be configured differently for
each workspace folder.

Any settings that are experimental or for debugging purposes are
marked as such.

<!--
All settings are uniquely identified by name such as `semanticTokens`
or `templateExtensions`.
However, for convenience of VS Code, each setting also has an
undocumented alias whose form is a dotted path such as
`ui.semanticTokens` or `build.templateExtensions`.
However, only the final segment is actually significant, so
`build.templateExtensions` is equivalent to `templateExtensions`.
All clients but VS Code should use the short form.
-->

<!-- This portion is generated by doc/generate from the ../internal/settings package. -->
<!-- BEGIN User: DO NOT MANUALLY EDIT THIS SECTION -->

* [Build](#build)
* [Formatting](#formatting)
* [UI](#ui)
  * [Completion](#completion)
  * [Diagnostic](#diagnostic)
  * [Documentation](#documentation)
  * [Inlayhint](#inlayhint)
  * [Navigation](#navigation)

<a id='build'></a>
## Build

<a id='buildFlags'></a>
### `buildFlags []string`

buildFlags is the set of flags passed on to the build system when invoked.
It is applied to queries like `go list`, which is used when discovering files.
The most common use is to set `-tags`.

Default: `[]`.

<a id='env'></a>
### `env map[string]string`

env adds environment variables to external commands run by `gopls`, most notably `go list`.

Default: `{}`.

<a id='directoryFilters'></a>
### `directoryFilters []string`

directoryFilters can be used to exclude unwanted directories from the
workspace. By default, all directories are included. Filters are an
operator, `+` to include and `-` to exclude, followed by a path prefix
relative to the workspace folder. They are evaluated in order, and
the last filter that applies to a path controls whether it is included.
The path prefix can be empty, so an initial `-` excludes everything.

DirectoryFilters also supports the `**` operator to match 0 or more directories.

Examples:

Exclude node_modules at current depth: `-node_modules`

Exclude node_modules at any depth: `-**/node_modules`

Include only project_a: `-` (exclude everything), `+project_a`

Include only project_a, but not node_modules inside it: `-`, `+project_a`, `-project_a/node_modules`

Default: `["-**/node_modules"]`.

<a id='templateExtensions'></a>
### `templateExtensions []string`

templateExtensions gives the extensions of file names that are treated
as template files. (The extension
is the part of the file name after the final dot.)

Default: `[]`.

<a id='memoryMode'></a>
### `memoryMode string`

**This setting is experimental and may be deleted.**

obsolete, no effect

Default: `""`.

<a id='expandWorkspaceToModule'></a>
### `expandWorkspaceToModule bool`

**This setting is experimental and may be deleted.**

expandWorkspaceToModule determines which packages are considered
"workspace packages" when the workspace is using modules.

Workspace packages affect the scope of workspace-wide operations. Notably,
gopls diagnoses all packages considered to be part of the workspace after
every keystroke, so by setting "ExpandWorkspaceToModule" to false, and
opening a nested workspace directory, you can reduce the amount of work
gopls has to do to keep your workspace up to date.

Default: `true`.

<a id='standaloneTags'></a>
### `standaloneTags []string`

standaloneTags specifies a set of build constraints that identify
individual Go source files that make up the entire main package of an
executable.

A common example of standalone main files is the convention of using the
directive `//go:build ignore` to denote files that are not intended to be
included in any package, for example because they are invoked directly by
the developer using `go run`.

Gopls considers a file to be a standalone main file if and only if it has
package name "main" and has a build directive of the exact form
"//go:build tag" or "// +build tag", where tag is among the list of tags
configured by this setting. Notably, if the build constraint is more
complicated than a simple tag (such as the composite constraint
`//go:build tag && go1.18`), the file is not considered to be a standalone
main file.

This setting is only supported when gopls is built with Go 1.16 or later.

Default: `["ignore"]`.

<a id='workspaceFiles'></a>
### `workspaceFiles []string`

workspaceFiles configures the set of globs that match files defining the
logical build of the current workspace. Any on-disk changes to any files
matching a glob specified here will trigger a reload of the workspace.

This setting need only be customized in environments with a custom
GOPACKAGESDRIVER.

Default: `[]`.

<a id='formatting'></a>
## Formatting

<a id='local'></a>
### `local string`

local is the equivalent of the `goimports -local` flag, which puts
imports beginning with this string after third-party packages. It should
be the prefix of the import path whose imports should be grouped
separately.

It is used when tidying imports (during an LSP Organize
Imports request) or when inserting new ones (for example,
during completion); an LSP Formatting request merely sorts the
existing imports.

Default: `""`.

<a id='gofumpt'></a>
### `gofumpt bool`

gofumpt indicates if we should run gofumpt formatting.

Default: `false`.

<a id='ui'></a>
## UI

<a id='codelenses'></a>
### `codelenses map[enum]bool`

codelenses overrides the enabled/disabled state of each of gopls'
sources of [Code Lenses](codelenses.md).

Example Usage:

```json5
"gopls": {
...
  "codelenses": {
    "generate": false,  // Don't show the `go generate` lens.
  }
...
}
```

Default: `{"generate":true,"regenerate_cgo":true,"run_govulncheck":true,"tidy":true,"upgrade_dependency":true,"vendor":true}`.

<a id='semanticTokens'></a>
### `semanticTokens bool`

**This setting is experimental and may be deleted.**

semanticTokens determines whether gopls will return a
SemanticTokensProvider at initialization, or respond
to request for semantic tokens.

Default: `false`.

<a id='noSemanticString'></a>
### `noSemanticString bool`

**This setting is experimental and may be deleted.**

noSemanticString turns off the sending of the semantic token 'string'

Deprecated: Use SemanticTokenTypes["string"] = false instead. See
golang/vscode-go#3632

Default: `false`.

<a id='noSemanticNumber'></a>
### `noSemanticNumber bool`

**This setting is experimental and may be deleted.**

noSemanticNumber turns off the sending of the semantic token 'number'

Deprecated: Use SemanticTokenTypes["number"] = false instead. See
golang/vscode-go#3632.

Default: `false`.

<a id='semanticTokenTypes'></a>
### `semanticTokenTypes map[string]bool`

**This setting is experimental and may be deleted.**

semanticTokenTypes configures the semantic token types. It allows
disabling types by setting each value to false.
By default, all types are enabled.

Default: `{}`.

<a id='semanticTokenModifiers'></a>
### `semanticTokenModifiers map[string]bool`

**This setting is experimental and may be deleted.**

semanticTokenModifiers configures the semantic token modifiers. It allows
disabling modifiers by setting each value to false.
By default, all modifiers are enabled.

Default: `{}`.

<a id='newGoFileHeader'></a>
### `newGoFileHeader bool`

newGoFileHeader enables automatic insertion of the copyright comment
and package declaration in a newly created Go file.

Default: `true`.

<a id='renameMovesSubpackages'></a>
### `renameMovesSubpackages bool`

**This setting is experimental and may be deleted.**

renameMovesSubpackages enables Rename operations on packages to
move subdirectories of the target package.

Default: `false`.

<a id='completion'></a>
## Completion

<a id='usePlaceholders'></a>
### `usePlaceholders bool`

placeholders enables placeholders for function parameters or struct
fields in completion responses.

Default: `false`.

<a id='completionBudget'></a>
### `completionBudget time.Duration`

**This setting is for debugging purposes only.**

completionBudget is the soft latency goal for completion requests. Most
requests finish in a couple milliseconds, but in some cases deep
completions can take much longer. As we use up our budget we
dynamically reduce the search scope to ensure we return timely
results. Zero means unlimited.

Default: `"100ms"`.

<a id='matcher'></a>
### `matcher enum`

**This is an advanced setting and should not be configured by most `gopls` users.**

matcher sets the algorithm that is used when calculating completion
candidates.

Must be one of:

* `"CaseInsensitive"`
* `"CaseSensitive"`
* `"Fuzzy"`

Default: `"Fuzzy"`.

<a id='experimentalPostfixCompletions'></a>
### `experimentalPostfixCompletions bool`

**This setting is experimental and may be deleted.**

experimentalPostfixCompletions enables artificial method snippets
such as "someSlice.sort!".

Default: `true`.

<a id='completeFunctionCalls'></a>
### `completeFunctionCalls bool`

completeFunctionCalls enables function call completion.

When completing a statement, or when a function return type matches the
expected of the expression being completed, completion may suggest call
expressions (i.e. may include parentheses).

Default: `true`.

<a id='diagnostic'></a>
## Diagnostic

<a id='analyses'></a>
### `analyses map[string]bool`

analyses specify analyses that the user would like to enable or disable.
A map of the names of analysis passes that should be enabled/disabled.
A full list of analyzers that gopls uses can be found in
[analyzers.md](https://github.com/golang/tools/blob/master/gopls/doc/analyzers.md).

Example Usage:

```json5
...
"analyses": {
  "unreachable": false, // Disable the unreachable analyzer.
  "unusedvariable": true  // Enable the unusedvariable analyzer.
}
...
```

Default: `{}`.

<a id='staticcheck'></a>
### `staticcheck bool`

**This setting is experimental and may be deleted.**

staticcheck configures the default set of analyses staticcheck.io.
These analyses are documented on
[Staticcheck's website](https://staticcheck.io/docs/checks/).

The "staticcheck" option has three values:
- false: disable all staticcheck analyzers
- true: enable all staticcheck analyzers
- unset: enable a subset of staticcheck analyzers
  selected by gopls maintainers for runtime efficiency
  and analytic precision.

Regardless of this setting, individual analyzers can be
selectively enabled or disabled using the `analyses` setting.

Default: `false`.

<a id='staticcheckProvided'></a>
### `staticcheckProvided bool`

**This setting is experimental and may be deleted.**


Default: `false`.

<a id='annotations'></a>
### `annotations map[enum]bool`

annotations specifies the various kinds of compiler
optimization details that should be reported as diagnostics
when enabled for a package by the "Toggle compiler
optimization details" (`gopls.gc_details`) command.

(Some users care only about one kind of annotation in their
profiling efforts. More importantly, in large packages, the
number of annotations can sometimes overwhelm the user
interface and exceed the per-file diagnostic limit.)

TODO(adonovan): rename this field to CompilerOptDetail.

Each enum must be one of:

* `"bounds"` controls bounds checking diagnostics.
* `"escape"` controls diagnostics about escape choices.
* `"inline"` controls diagnostics about inlining choices.
* `"nil"` controls nil checks.

Default: `{"bounds":true,"escape":true,"inline":true,"nil":true}`.

<a id='vulncheck'></a>
### `vulncheck enum`

**This setting is experimental and may be deleted.**

vulncheck enables vulnerability scanning.

Must be one of:

* `"Imports"`: In Imports mode, `gopls` will report vulnerabilities that affect packages
directly and indirectly used by the analyzed main module.
* `"Off"`: Disable vulnerability analysis.
* `"Prompt"`: Vulncheck can be triggered via prompt.

Default: `"Prompt"`.

<a id='diagnosticsDelay'></a>
### `diagnosticsDelay time.Duration`

**This is an advanced setting and should not be configured by most `gopls` users.**

diagnosticsDelay controls the amount of time that gopls waits
after the most recent file modification before computing deep diagnostics.
Simple diagnostics (parsing and type-checking) are always run immediately
on recently modified packages.

This option must be set to a valid duration string, for example `"250ms"`.

Default: `"1s"`.

<a id='diagnosticsTrigger'></a>
### `diagnosticsTrigger enum`

**This setting is experimental and may be deleted.**

diagnosticsTrigger controls when to run diagnostics.

Must be one of:

* `"Edit"`: Trigger diagnostics on file edit and save. (default)
* `"Save"`: Trigger diagnostics only on file save. Events like initial workspace load
or configuration change will still trigger diagnostics.

Default: `"Edit"`.

<a id='analysisProgressReporting'></a>
### `analysisProgressReporting bool`

analysisProgressReporting controls whether gopls sends progress
notifications when construction of its index of analysis facts is taking a
long time. Cancelling these notifications will cancel the indexing task,
though it will restart after the next change in the workspace.

When a package is opened for the first time and heavyweight analyses such as
staticcheck are enabled, it can take a while to construct the index of
analysis facts for all its dependencies. The index is cached in the
filesystem, so subsequent analysis should be faster.

Default: `true`.

<a id='documentation'></a>
## Documentation

<a id='hoverKind'></a>
### `hoverKind enum`

hoverKind controls the information that appears in the hover text.
SingleLine is intended for use only by authors of editor plugins.

Must be one of:

* `"FullDocumentation"`
* `"NoDocumentation"`
* `"SingleLine"`
* `"Structured"` is a misguided experimental setting that returns a JSON
hover format. This setting should not be used, as it will be removed in a
future release of gopls.
* `"SynopsisDocumentation"`

Default: `"FullDocumentation"`.

<a id='linkTarget'></a>
### `linkTarget string`

linkTarget is the base URL for links to Go package
documentation returned by LSP operations such as Hover and
DocumentLinks and in the CodeDescription field of each
Diagnostic.

It might be one of:

* `"godoc.org"`
* `"pkg.go.dev"`

If company chooses to use its own `godoc.org`, its address can be used as well.

Modules matching the GOPRIVATE environment variable will not have
documentation links in hover.

Default: `"pkg.go.dev"`.

<a id='linksInHover'></a>
### `linksInHover enum`

linksInHover controls the presence of documentation links in hover markdown.

Must be one of:

* false: do not show links
* true: show links to the `linkTarget` domain
* `"gopls"`: show links to gopls' internal documentation viewer

Default: `true`.

<a id='inlayhint'></a>
## Inlayhint

<a id='hints'></a>
### `hints map[enum]bool`

**This setting is experimental and may be deleted.**

hints specify inlay hints that users want to see. A full list of hints
that gopls uses can be found in
[inlayHints.md](https://github.com/golang/tools/blob/master/gopls/doc/inlayHints.md).

Default: `{}`.

<a id='navigation'></a>
## Navigation

<a id='importShortcut'></a>
### `importShortcut enum`

importShortcut specifies whether import statements should link to
documentation or go to definitions.

Must be one of:

* `"Both"`
* `"Definition"`
* `"Link"`

Default: `"Both"`.

<a id='symbolMatcher'></a>
### `symbolMatcher enum`

**This is an advanced setting and should not be configured by most `gopls` users.**

symbolMatcher sets the algorithm that is used when finding workspace symbols.

Must be one of:

* `"CaseInsensitive"`
* `"CaseSensitive"`
* `"FastFuzzy"`
* `"Fuzzy"`

Default: `"FastFuzzy"`.

<a id='symbolStyle'></a>
### `symbolStyle enum`

**This is an advanced setting and should not be configured by most `gopls` users.**

symbolStyle controls how symbols are qualified in symbol responses.

Example Usage:

```json5
"gopls": {
...
  "symbolStyle": "Dynamic",
...
}
```

Must be one of:

* `"Dynamic"` uses whichever qualifier results in the highest scoring
match for the given symbol query. Here a "qualifier" is any "/" or "."
delimited suffix of the fully qualified symbol. i.e. "to/pkg.Foo.Field" or
just "Foo.Field".
* `"Full"` is fully qualified symbols, i.e.
"path/to/pkg.Foo.Field".
* `"Package"` is package qualified symbols i.e.
"pkg.Foo.Field".

Default: `"Dynamic"`.

<a id='symbolScope'></a>
### `symbolScope enum`

symbolScope controls which packages are searched for workspace/symbol
requests. When the scope is "workspace", gopls searches only workspace
packages. When the scope is "all", gopls searches all loaded packages,
including dependencies and the standard library.

Must be one of:

* `"all"` matches symbols in any loaded package, including
dependencies.
* `"workspace"` matches symbols in workspace packages only.

Default: `"all"`.

<a id='maxFileCacheBytes'></a>
### `maxFileCacheBytes int64`

**This setting is experimental and may be deleted.**

maxFileCacheBytes sets a soft limit on the file cache size in bytes.
If zero, the default budget is used.

The cache may temporarily use more than this amount.
Also, this parameter limits file contents; disk block usage
as measured by du(1) may be significantly higher.

Default: `0`.

<a id='verboseOutput'></a>
### `verboseOutput bool`

**This setting is for debugging purposes only.**

verboseOutput enables additional debug logging.

Default: `false`.

<!-- END User: DO NOT MANUALLY EDIT THIS SECTION -->


================================================
FILE: gopls/doc/troubleshooting.md
================================================
---
title: "Gopls: Troubleshooting"
---

If you suspect that `gopls` is crashing or not working correctly, please follow the troubleshooting steps below.

If `gopls` is using too much memory, please follow the steps under [Memory usage](#debug-memory-usage).

## Steps

VS Code users should follow [their troubleshooting guide](https://github.com/golang/vscode-go/blob/master/docs/troubleshooting.md), which has more a more specific version of these instructions.

1. Verify that your project is in good shape by working with it outside of your editor. Running a command like `go build ./...` in the workspace directory will compile everything. For modules, `go mod tidy` is another good check, though it may modify your `go.mod`.
1. Check that your editor isn't showing any diagnostics that indicate a problem with your workspace. They may appear as diagnostics on a Go file's package declaration, diagnostics in a go.mod file, or as a status or progress message. Problems in the workspace configuration can cause many different symptoms. See the [workspace setup instructions](workspace.md) for help.
1. Make sure `gopls` is up to date by following the [installation instructions](index.md#installation), then [restarting gopls](#restart-gopls).
1. Optionally, [ask for help](#ask-for-help) on Gophers Slack.
1. Finally, [report the issue](#file-an-issue) to the `gopls` developers.

## Restart `gopls`

`gopls` has no persistent state, so restarting it will fix transient problems. This is good and bad: good, because you can keep working, and bad, because you won't be able to debug the issue until it recurs.

In most cases, closing all your open editors will guarantee that `gopls` is killed and restarted. If you don't want to do that, there may be an editor command you can use to restart only `gopls`. Note that some `vim` configurations keep the server alive for a while after the editor exits; you may need to explicitly kill `gopls` if you use `vim`.

## Ask for help

Gophers Slack has active editor-specific channels like [#emacs](https://gophers.slack.com/archives/C0HKHULEM), [#vim](https://gophers.slack.com/archives/C07GBR52P), and [#vscode](https://gophers.slack.com/archives/C2B4L99RS) that can help debug further. If you're confident the problem is with `gopls`, you can go straight to [#gopls](https://gophers.slack.com/archives/CJZH85XCZ). Invites are [available to everyone](https://invite.slack.golangbridge.org). Come prepared with a short description of the issue, and try to be available to answer questions for a while afterward.

## File an issue

We can't diagnose a problem from just a description. When filing an issue, please include as much as possible of the following information:

1. Your editor and any settings you have configured (for example, your VSCode `settings.json` file).
1. A sample program that reproduces the issue, if possible.
1. The output of `gopls version` on the command line.
1. A complete gopls log file from a session where the issue occurred. It should have a `go env for <workspace folder>` log line near the beginning. It's also helpful to tell us the timestamp the problem occurred, so we can find it the log. See the [instructions](#capture-logs) for information on how to capture gopls logs.

Your editor may have a command that fills out some of the necessary information, such as `:GoReportGitHubIssue` in `vim-go`. Otherwise, you can use `gopls bug` on the command line. If neither of those work you can start from scratch directly on the [Go issue tracker](https://github.com/golang/go/issues/new?title=x%2Ftools%2Fgopls%3A%20%3Cfill%20this%20in%3E).

## Capture logs

You may have to change your editor's configuration to pass a `-logfile` flag to gopls.

To increase the level of detail in your logs, start `gopls` with the `-rpc.trace` flag. To start a debug server that will allow you to see profiles and memory usage, start `gopls` with `serve --debug=localhost:6060`. You will then be able to view debug information by navigating to `localhost:6060`.

If you are unsure of how to pass a flag to `gopls` through your editor, please see the [documentation for your editor](index.md#editors).

## Debug memory usage

`gopls` automatically writes out memory debug information when your usage exceeds 1GB. This information can be found in your temporary directory with names like `gopls.1234-5GiB-withnames.zip`. On Windows, your temporary directory will be located at `%TMP%`, and on Unixes, it will be `$TMPDIR`, which is usually `/tmp`. Please [file an issue](#file-an-issue) with this memory debug information attached. If you are uncomfortable sharing the package names of your code, you can share the `-nonames` zip instead, but it's much less useful.


================================================
FILE: gopls/doc/workspace.md
================================================
---
title: "Gopls: Setting up your workspace"
---

In the language server protocol, a "workspace" consists of a folder along with
per-folder configuration. Some LSP clients such as VS Code allow configuring
workspaces explicitly, while others do so automatically by looking for special
files defining a workspace root (such as a `.git` directory or `go.mod` file).

In order to function, gopls needs a defined scope in which language features
like references, rename, and implementation should operate. Put differently,
gopls needs to infer from the LSP workspace which  `go build` invocations you
would use to build your workspace, including the working directory,
environment, and build flags.

In the past, it could be tricky to set up your workspace so that gopls would
infer the correct build information. It required opening the correct directory
or using a `go.work` file to tell gopls about the modules you're working on,
and configuring the correct operating system and architecture in advance.
When this didn't work as expected, gopls would often fail in mysterious
ways--the dreaded "No packages found" error.

Starting with gopls v0.15.0, workspace configuration is much simpler, and gopls
will typically work when you open a Go file anywhere in your workspace. If it
isn't working for you, or if you want to better understand how gopls models
your workspace, please read on.

## Workspace builds

Starting with gopls v0.15.0, gopls will guess the builds you are working on
based on the set of open files. When you open a file in a workspace folder,
gopls checks whether the file is contained in a module, `go.work` workspace, or
GOPATH directory, and configures the build accordingly. Additionally, if you
open a file that is constrained to a different operating system or
architecture, for example opening `foo_windows.go` when working on Linux, gopls
will create a scope with `GOOS` and `GOARCH` set to a value that matches the
file.

For example, suppose we had a repository with three modules: `moda`, `modb`,
and `modc`, and a `go.work` file using modules `moda` and `modb`. If we open
the files `moda/a.go`, `modb/b.go`, `moda/a_windows.go`, and `modc/c.go`, gopls
will automatically create three builds:

![Zero Config gopls](assets/zeroconfig.png)

This allows gopls to _just work_ when you open a Go file, but it does come with
several caveats:

- It causes gopls to do more work, since it is now tracking three builds
  instead of one. However, the recent
  [scalability redesign](https://go.dev/blog/gopls-scalability)
  allows much of this work to be avoided through efficient caching.
- For operations invoked from a given file, such as "References"
  or "Implementations", gopls executes the operation in
  _the default build for that file_. For example, finding references to
  a symbol `S` from `foo_linux.go` will return references from the Linux build,
  and finding references to the same symbol `S` from `foo_windows.go` will
  return references from the Windows build. Gopls searches the default build
  for the file, but it doesn't search all the other possible builds (even
  though that would be nice) because it is liable to be too expensive.
  Issues [#65757](https://go.dev/issue/65757) and
  [#65755](https://go.dev/issue/65755) propose improvements to this behavior.
- When selecting a `GOOS/GOARCH` combination to match a build-constrained file,
  gopls will choose the first matching combination from
  [this list](https://cs.opensource.google/go/x/tools/+/master:gopls/internal/cache/port.go;l=30;drc=f872b3d6f05822d290bc7bdd29db090fd9d89f5c).
  In some cases, that may be surprising.
- When working in a `GOOS/GOARCH` constrained file that does not match your
  default toolchain, `CGO_ENABLED=0` is implicitly set, since a C toolchain for
  that target is unlikely to be available. This means that gopls will not
  work in files including `import "C"`. Issue
  [#65758](https://go.dev/issue/65758) may lead to improvements in this
  behavior.
- Gopls is currently unable to guess build flags that include arbitrary
  user-defined build constraints, such as a file with the build directive
  `//go:build mytag`. Issue [#65089](https://go.dev/issue/65089) proposes
  a heuristic by which gopls could handle this automatically.

Please provide feedback on this behavior by upvoting or commenting the issues
mentioned above, or opening a [new issue](https://go.dev/issue/new) for other
improvements you'd like to see.

## When to use a `go.work` file for development

Starting with Go 1.18, the `go` command has built-in support for multi-module
workspaces specified by [`go.work`](https://go.dev/ref/mod#workspaces) files.
Gopls will recognize these files if they are present in your workspace.

Use a `go.work` file when:

- you want to work on multiple modules simultaneously in a single logical
  build, for example if you want changes to one module to be reflected in
  another.
- you want to improve gopls' memory usage or performance by reducing the number
  of builds it must track.
- you want gopls to know which modules you are working on in a multi-module
  workspace, without opening any files. For example, it may be convenient to use
  `workspace/symbol` queries before any files are open.
- you are using gopls v0.14.2 or earlier, and want to work on multiple
  modules.

For example, suppose this repo is checked out into the `$WORK/tools` directory,
and [`x/mod`](https://pkg.go.dev/golang.org/x/mod) is checked out into
`$WORK/mod`, and you are working on a new `x/mod` API for editing `go.mod`
files that you want to simultaneously integrate into gopls.

You can work on both `golang.org/x/tools/gopls` and `golang.org/x/mod`
simultaneously by creating a `go.work` file:

```sh
cd $WORK
go work init
go work use tools/gopls mod
```

then opening the `$WORK` directory in your editor.

## When to manually configure `GOOS`, `GOARCH`, or `-tags`

As described in the first section, gopls v0.15.0 and later will try to
configure a new build scope automatically when you open a file that doesn't
match the system default operating system (`GOOS`) or architecture (`GOARCH`).

However, per the caveats listed in that section, this automatic behavior comes
with limitations. Customize your gopls environment by setting `GOOS` or
`GOARCH` in your
[`"build.env"`](https://github.com/golang/tools/blob/master/gopls/doc/settings.md#env)
or `-tags=...` in your"
["build.buildFlags"](https://github.com/golang/tools/blob/master/gopls/doc/settings.md#buildflags)
when:

- You want to modify the default build environment.
- Gopls is not guessing the `GOOS/GOARCH` combination you want to use for
  cross platform development.
- You need to work on a file that is constrained by a user-defined build tags,
  such as the build directive `//go:build mytag`.

## GOPATH mode

When opening a directory within a `GOPATH` directory, the workspace scope will
be just that directory and all directories contained within it. Note that
opening a large GOPATH directory can make gopls very slow to start.


================================================
FILE: gopls/go.mod
================================================
module golang.org/x/tools/gopls

go 1.26.0

require (
	github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c
	github.com/fsnotify/fsnotify v1.9.0
	github.com/google/go-cmp v0.7.0
	github.com/google/jsonschema-go v0.4.2
	github.com/jba/templatecheck v0.7.1
	github.com/modelcontextprotocol/go-sdk v1.4.0
	golang.org/x/mod v0.34.0
	golang.org/x/sync v0.20.0
	golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c
	golang.org/x/text v0.35.0
	golang.org/x/tools v0.42.0
	golang.org/x/vuln v1.1.4
	gopkg.in/yaml.v3 v3.0.1
	honnef.co/go/tools v0.7.0
	mvdan.cc/gofumpt v0.9.2
	mvdan.cc/xurls/v2 v2.6.0
)

require (
	github.com/BurntSushi/toml v1.6.0 // indirect
	github.com/fatih/camelcase v1.0.0 // indirect
	github.com/fatih/structtag v1.2.0 // indirect
	github.com/google/safehtml v0.1.0 // indirect
	github.com/segmentio/asm v1.2.1 // indirect
	github.com/segmentio/encoding v0.5.3 // indirect
	github.com/yosida95/uritemplate/v3 v3.0.2 // indirect
	golang.org/x/exp/typeparams v0.0.0-20260218203240-3dfff04db8fa // indirect
	golang.org/x/oauth2 v0.36.0 // indirect
	golang.org/x/sys v0.42.0 // indirect
	golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated // indirect
	gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 // indirect
)

replace golang.org/x/tools => ../


================================================
FILE: gopls/go.sum
================================================
github.com/BurntSushi/toml v1.6.0 h1:dRaEfpa2VI55EwlIW72hMRHdWouJeRF7TPYhI+AUQjk=
github.com/BurntSushi/toml v1.6.0/go.mod h1:ukJfTF/6rtPPRCnwkur4qwRxa8vTRFBF0uk2lLoLwho=
github.com/fatih/camelcase v1.0.0 h1:hxNvNX/xYBp0ovncs8WyWZrOrpBNub/JfaMvbURyft8=
github.com/fatih/camelcase v1.0.0/go.mod h1:yN2Sb0lFhZJUdVvtELVWefmrXpuZESvPmqwoZc+/fpc=
github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c h1:dDSgAjoOMp8da3egfz0t2S+t8RGOpEmEXZubcGuc0Bg=
github.com/fatih/gomodifytags v1.17.1-0.20250423142747-f3939df9aa3c/go.mod h1:YVLagR57bBxMai8IAEc7V4E/MWUYi0oUutLrZcTcnI8=
github.com/fatih/structtag v1.2.0 h1:/OdNE99OxoI/PqaW/SuSK9uxxT3f/tcSZgon/ssNSx4=
github.com/fatih/structtag v1.2.0/go.mod h1:mBJUNpUnHmRKrKlQQlmCrh5PuhftFbNv8Ys4/aAZl94=
github.com/fsnotify/fsnotify v1.9.0 h1:2Ml+OJNzbYCTzsxtv8vKSFD9PbJjmhYF14k/jKC7S9k=
github.com/fsnotify/fsnotify v1.9.0/go.mod h1:8jBTzvmWwFyi3Pb8djgCCO5IBqzKJ/Jwo8TRcHyHii0=
github.com/go-quicktest/qt v1.101.0 h1:O1K29Txy5P2OK0dGo59b7b0LR6wKfIhttaAhHUyn7eI=
github.com/go-quicktest/qt v1.101.0/go.mod h1:14Bz/f7NwaXPtdYEgzsx46kqSxVwTbzVZsDC26tQJow=
github.com/golang-jwt/jwt/v5 v5.3.0 h1:pv4AsKCKKZuqlgs5sUmn4x8UlGa0kEVt/puTpKx9vvo=
github.com/golang-jwt/jwt/v5 v5.3.0/go.mod h1:fxCRLWMO43lRc8nhHWY6LGqRcf+1gQWArsqaEUEa5bE=
github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
github.com/google/go-cmp v0.7.0 h1:wk8382ETsv4JYUZwIsn6YpYiWiBsYLSJiTsyBybVuN8=
github.com/google/go-cmp v0.7.0/go.mod h1:pXiqmnSA92OHEEa9HXL2W4E7lf9JzCmGVUdgjX3N/iU=
github.com/google/jsonschema-go v0.4.2 h1:tmrUohrwoLZZS/P3x7ex0WAVknEkBZM46iALbcqoRA8=
github.com/google/jsonschema-go v0.4.2/go.mod h1:r5quNTdLOYEz95Ru18zA0ydNbBuYoo9tgaYcxEYhJVE=
github.com/google/safehtml v0.1.0 h1:EwLKo8qawTKfsi0orxcQAZzu07cICaBeFMegAU9eaT8=
github.com/google/safehtml v0.1.0/go.mod h1:L4KWwDsUJdECRAEpZoBn3O64bQaywRscowZjJAzjHnU=
github.com/jba/templatecheck v0.7.1 h1:yOEIFazBEwzdTPYHZF3Pm81NF1ksxx1+vJncSEwvjKc=
github.com/jba/templatecheck v0.7.1/go.mod h1:n1Etw+Rrw1mDDD8dDRsEKTwMZsJ98EkktgNJC6wLUGo=
github.com/kr/pretty v0.3.1 h1:flRD4NNwYAUpkphVc1HcthR4KEIFJ65n8Mw5qdRn3LE=
github.com/kr/pretty v0.3.1/go.mod h1:hoEshYVHaxMs3cyo3Yncou5ZscifuDolrwPKZanG3xk=
github.com/kr/text v0.2.0 h1:5Nx0Ya0ZqY2ygV366QzturHI13Jq95ApcVaJBhpS+AY=
github.com/kr/text v0.2.0/go.mod h1:eLer722TekiGuMkidMxC/pM04lWEeraHUUmBw8l2grE=
github.com/modelcontextprotocol/go-sdk v1.4.0 h1:u0kr8lbJc1oBcawK7Df+/ajNMpIDFE41OEPxdeTLOn8=
github.com/modelcontextprotocol/go-sdk v1.4.0/go.mod h1:Nxc2n+n/GdCebUaqCOhTetptS17SXXNu9IfNTaLDi1E=
github.com/rogpeppe/go-internal v1.14.1 h1:UQB4HGPB6osV0SQTLymcB4TgvyWu6ZyliaW0tI/otEQ=
github.com/rogpeppe/go-internal v1.14.1/go.mod h1:MaRKkUm5W0goXpeCfT7UZI6fk/L7L7so1lCWt35ZSgc=
github.com/segmentio/asm v1.2.1 h1:DTNbBqs57ioxAD4PrArqftgypG4/qNpXoJx8TVXxPR0=
github.com/segmentio/asm v1.2.1/go.mod h1:BqMnlJP91P8d+4ibuonYZw9mfnzI9HfxselHZr5aAcs=
github.com/segmentio/encoding v0.5.3 h1:OjMgICtcSFuNvQCdwqMCv9Tg7lEOXGwm1J5RPQccx6w=
github.com/segmentio/encoding v0.5.3/go.mod h1:HS1ZKa3kSN32ZHVZ7ZLPLXWvOVIiZtyJnO1gPH1sKt0=
github.com/yosida95/uritemplate/v3 v3.0.2 h1:Ed3Oyj9yrmi9087+NczuL5BwkIc4wvTb5zIM+UJPGz4=
github.com/yosida95/uritemplate/v3 v3.0.2/go.mod h1:ILOh0sOhIJR3+L/8afwt/kE++YT040gmv5BQTMR2HP4=
github.com/yuin/goldmark v1.4.13/go.mod h1:6yULJ656Px+3vBD8DxQVa3kxgyrAnzto9xy5taEt/CY=
golang.org/x/crypto v0.19.0/go.mod h1:Iy9bg/ha4yyC70EfRS8jz+B6ybOBKMaSxLj6P6oBDfU=
golang.org/x/crypto v0.39.0/go.mod h1:L+Xg3Wf6HoL4Bn4238Z6ft6KfEpN0tJGo53AAPC632U=
golang.org/x/crypto v0.40.0/go.mod h1:Qr1vMER5WyS2dfPHAlsOj01wgLbsyWtFn/aY+5+ZdxY=
golang.org/x/crypto v0.41.0/go.mod h1:pO5AFd7FA68rFak7rOAGVuygIISepHftHnr8dr6+sUc=
golang.org/x/crypto v0.42.0/go.mod h1:4+rDnOTJhQCx2q7/j6rAN5XDw8kPjeaXEUR2eL94ix8=
golang.org/x/crypto v0.43.0/go.mod h1:BFbav4mRNlXJL4wNeejLpWxB7wMbc79PdRGhWKncxR0=
golang.org/x/crypto v0.44.0/go.mod h1:013i+Nw79BMiQiMsOPcVCB5ZIJbYkerPrGnOa00tvmc=
golang.org/x/crypto v0.46.0/go.mod h1:Evb/oLKmMraqjZ2iQTwDwvCtJkczlDuTmdJXoZVzqU0=
golang.org/x/crypto v0.47.0/go.mod h1:ff3Y9VzzKbwSSEzWqJsJVBnWmRwRSHt/6Op5n9bQc4A=
golang.org/x/crypto v0.48.0/go.mod h1:r0kV5h3qnFPlQnBSrULhlsRfryS2pmewsg+XfMgkVos=
golang.org/x/crypto v0.49.0/go.mod h1:ErX4dUh2UM+CFYiXZRTcMpEcN8b/1gxEuv3nODoYtCA=
golang.org/x/exp/typeparams v0.0.0-20260218203240-3dfff04db8fa h1:6Wi43P0isP8Nl8D4qJmA3VC4FswVH0RJkr5cauo67SQ=
golang.org/x/exp/typeparams v0.0.0-20260218203240-3dfff04db8fa/go.mod h1:PqrXSW65cXDZH0k4IeUbhmg/bcAZDbzNz3byBpKCsXo=
golang.org/x/mod v0.8.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
golang.org/x/mod v0.25.0/go.mod h1:IXM97Txy2VM4PJ3gI61r1YEk/gAj6zAHN3AdZt6S9Ww=
golang.org/x/mod v0.26.0/go.mod h1:/j6NAhSk8iQ723BGAUyoAcn7SlD7s15Dp9Nd/SfeaFQ=
golang.org/x/mod v0.27.0/go.mod h1:rWI627Fq0DEoudcK+MBkNkCe0EetEaDSwJJkCcjpazc=
golang.org/x/mod v0.28.0/go.mod h1:yfB/L0NOf/kmEbXjzCPOx1iK1fRutOydrCMsqRhEBxI=
golang.org/x/mod v0.29.0/go.mod h1:NyhrlYXJ2H4eJiRy/WDBO6HMqZQ6q9nk4JzS3NuCK+w=
golang.org/x/mod v0.30.0/go.mod h1:lAsf5O2EvJeSFMiBxXDki7sCgAxEUcZHXoXMKT4GJKc=
golang.org/x/mod v0.31.0/go.mod h1:43JraMp9cGx1Rx3AqioxrbrhNsLl2l/iNAvuBkrezpg=
golang.org/x/mod v0.32.0/go.mod h1:SgipZ/3h2Ci89DlEtEXWUk/HteuRin+HHhN+WbNhguU=
golang.org/x/mod v0.33.0/go.mod h1:swjeQEj+6r7fODbD2cqrnje9PnziFuw4bmLbBZFrQ5w=
golang.org/x/mod v0.34.0 h1:xIHgNUUnW6sYkcM5Jleh05DvLOtwc6RitGHbDk4akRI=
golang.org/x/mod v0.34.0/go.mod h1:ykgH52iCZe79kzLLMhyCUzhMci+nQj+0XkbXpNYtVjY=
golang.org/x/net v0.10.0/go.mod h1:0qNGK6F8kojg2nk9dLZ2mShWaEBan6FAoqfSigmmuDg=
golang.org/x/net v0.21.0/go.mod h1:bIjVDfnllIU7BJ2DNgfnXvpSvtn8VRwhlsaeUTyUS44=
golang.org/x/net v0.41.0/go.mod h1:B/K4NNqkfmg07DQYrbwvSluqCJOOXwUjeb/5lOisjbA=
golang.org/x/net v0.42.0/go.mod h1:FF1RA5d3u7nAYA4z2TkclSCKh68eSXtiFwcWQpPXdt8=
golang.org/x/net v0.43.0/go.mod h1:vhO1fvI4dGsIjh73sWfUVjj3N7CA9WkKJNQm2svM6Jg=
golang.org/x/net v0.45.0/go.mod h1:ECOoLqd5U3Lhyeyo/QDCEVQ4sNgYsqvCZ722XogGieY=
golang.org/x/net v0.46.0/go.mod h1:Q9BGdFy1y4nkUwiLvT5qtyhAnEHgnQ/zd8PfU6nc210=
golang.org/x/net v0.47.0/go.mod h1:/jNxtkgq5yWUGYkaZGqo27cfGZ1c5Nen03aYrrKpVRU=
golang.org/x/net v0.48.0/go.mod h1:+ndRgGjkh8FGtu1w1FGbEC31if4VrNVMuKTgcAAnQRY=
golang.org/x/net v0.49.0/go.mod h1:/ysNB2EvaqvesRkuLAyjI1ycPZlQHM3q01F02UY/MV8=
golang.org/x/net v0.51.0/go.mod h1:aamm+2QF5ogm02fjy5Bb7CQ0WMt1/WVM7FtyaTLlA9Y=
golang.org/x/net v0.52.0/go.mod h1:R1MAz7uMZxVMualyPXb+VaqGSa3LIaUqk0eEt3w36Sw=
golang.org/x/oauth2 v0.36.0 h1:peZ/1z27fi9hUOFCAZaHyrpWG5lwe0RJEEEeH0ThlIs=
golang.org/x/oauth2 v0.36.0/go.mod h1:YDBUJMTkDnJS+A4BP4eZBjCqtokkg1hODuPjwiGPO7Q=
golang.org/x/sync v0.15.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
golang.org/x/sync v0.16.0/go.mod h1:1dzgHSNfp02xaA81J2MS99Qcpr2w7fw1gpm99rleRqA=
golang.org/x/sync v0.17.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
golang.org/x/sync v0.18.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
golang.org/x/sync v0.19.0/go.mod h1:9KTHXmSnoGruLpwFjVSX0lNNA75CykiMECbovNTZqGI=
golang.org/x/sync v0.20.0 h1:e0PTpb7pjO8GAtTs2dQ6jYa5BWYlMuX047Dco/pItO4=
golang.org/x/sync v0.20.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
golang.org/x/sys v0.5.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.8.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
golang.org/x/sys v0.17.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
golang.org/x/sys v0.33.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/sys v0.34.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/sys v0.35.0/go.mod h1:BJP2sWEmIv4KK5OTEluFJCKSidICx8ciO85XgH3Ak8k=
golang.org/x/sys v0.36.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.37.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.38.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.39.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.40.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
golang.org/x/sys v0.42.0 h1:omrd2nAlyT5ESRdCLYdm3+fMfNFE/+Rf4bDIQImRJeo=
golang.org/x/sys v0.42.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c h1:6a8FdnNk6bTXBjR4AGKFgUKuo+7GnR3FX5L7CbveeZc=
golang.org/x/telemetry v0.0.0-20260311193753-579e4da9a98c/go.mod h1:TpUTTEp9frx7rTdLpC9gFG9kdI7zVLFTFFlqaH2Cncw=
golang.org/x/term v0.8.0/go.mod h1:xPskH00ivmX89bAKVGSKKtLOWNx2+17Eiy94tnKShWo=
golang.org/x/term v0.17.0/go.mod h1:lLRBjIVuehSbZlaOtGMbcMncT+aqLLLmKrsjNrUguwk=
golang.org/x/term v0.32.0/go.mod h1:uZG1FhGx848Sqfsq4/DlJr3xGGsYMu/L5GW4abiaEPQ=
golang.org/x/term v0.33.0/go.mod h1:s18+ql9tYWp1IfpV9DmCtQDDSRBUjKaw9M1eAv5UeF0=
golang.org/x/term v0.34.0/go.mod h1:5jC53AEywhIVebHgPVeg0mj8OD3VO9OzclacVrqpaAw=
golang.org/x/term v0.35.0/go.mod h1:TPGtkTLesOwf2DE8CgVYiZinHAOuy5AYUYT1lENIZnA=
golang.org/x/term v0.36.0/go.mod h1:Qu394IJq6V6dCBRgwqshf3mPF85AqzYEzofzRdZkWss=
golang.org/x/term v0.37.0/go.mod h1:5pB4lxRNYYVZuTLmy8oR2BH8dflOR+IbTYFD8fi3254=
golang.org/x/term v0.38.0/go.mod h1:bSEAKrOT1W+VSu9TSCMtoGEOUcKxOKgl3LE5QEF/xVg=
golang.org/x/term v0.39.0/go.mod h1:yxzUCTP/U+FzoxfdKmLaA0RV1WgE0VY7hXBwKtY/4ww=
golang.org/x/term v0.40.0/go.mod h1:w2P8uVp06p2iyKKuvXIm7N/y0UCRt3UfJTfZ7oOpglM=
golang.org/x/term v0.41.0/go.mod h1:3pfBgksrReYfZ5lvYM0kSO0LIkAl4Yl2bXOkKP7Ec2A=
golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
golang.org/x/text v0.9.0/go.mod h1:e1OnstbJyHTd6l/uOt8jFFHp6TRDWZR/bV3emEE/zU8=
golang.org/x/text v0.14.0/go.mod h1:18ZOQIKpY8NJVqYksKHtTdi31H5itFRjB5/qKTNYzSU=
golang.org/x/text v0.26.0/go.mod h1:QK15LZJUUQVJxhz7wXgxSy/CJaTFjd0G+YLonydOVQA=
golang.org/x/text v0.27.0/go.mod h1:1D28KMCvyooCX9hBiosv5Tz/+YLxj0j7XhWjpSUF7CU=
golang.org/x/text v0.28.0/go.mod h1:U8nCwOR8jO/marOQ0QbDiOngZVEBB7MAiitBuMjXiNU=
golang.org/x/text v0.29.0/go.mod h1:7MhJOA9CD2qZyOKYazxdYMF85OwPdEr9jTtBpO7ydH4=
golang.org/x/text v0.30.0/go.mod h1:yDdHFIX9t+tORqspjENWgzaCVXgk0yYnYuSZ8UzzBVM=
golang.org/x/text v0.31.0/go.mod h1:tKRAlv61yKIjGGHX/4tP1LTbc13YSec1pxVEWXzfoeM=
golang.org/x/text v0.32.0/go.mod h1:o/rUWzghvpD5TXrTIBuJU77MTaN0ljMWE47kxGJQ7jY=
golang.org/x/text v0.33.0/go.mod h1:LuMebE6+rBincTi9+xWTY8TztLzKHc/9C1uBCG27+q8=
golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
golang.org/x/text v0.35.0 h1:JOVx6vVDFokkpaq1AEptVzLTpDe9KGpj5tR4/X+ybL8=
golang.org/x/text v0.35.0/go.mod h1:khi/HExzZJ2pGnjenulevKNX1W67CUy0AsXcNubPGCA=
golang.org/x/tools/go/expect v0.1.1-deprecated h1:jpBZDwmgPhXsKZC6WhL20P4b/wmnpsEAGHaNy0n/rJM=
golang.org/x/tools/go/expect v0.1.1-deprecated/go.mod h1:eihoPOH+FgIqa3FpoTwguz/bVUSGBlGQU67vpBeOrBY=
golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated h1:1h2MnaIAIXISqTFKdENegdpAgUXz6NrPEsbIeWaBRvM=
golang.org/x/tools/go/packages/packagestest v0.1.1-deprecated/go.mod h1:RVAQXBGNv1ib0J382/DPCRS/BPnsGebyM1Gj5VSDpG8=
golang.org/x/vuln v1.1.4 h1:Ju8QsuyhX3Hk8ma3CesTbO8vfJD9EvUBgHvkxHBzj0I=
golang.org/x/vuln v1.1.4/go.mod h1:F+45wmU18ym/ca5PLTPLsSzr2KppzswxPP603ldA67s=
gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
honnef.co/go/tools v0.7.0 h1:w6WUp1VbkqPEgLz4rkBzH/CSU6HkoqNLp6GstyTx3lU=
honnef.co/go/tools v0.7.0/go.mod h1:pm29oPxeP3P82ISxZDgIYeOaf9ta6Pi0EWvCFoLG2vc=
mvdan.cc/gofumpt v0.9.2 h1:zsEMWL8SVKGHNztrx6uZrXdp7AX8r421Vvp23sz7ik4=
mvdan.cc/gofumpt v0.9.2/go.mod h1:iB7Hn+ai8lPvofHd9ZFGVg2GOr8sBUw1QUWjNbmIL/s=
mvdan.cc/xurls/v2 v2.6.0 h1:3NTZpeTxYVWNSokW3MKeyVkz/j7uYXYiMtXRUfmjbgI=
mvdan.cc/xurls/v2 v2.6.0/go.mod h1:bCvEZ1XvdA6wDnxY7jPPjEmigDtvtvPXAD/Exa9IMSk=


================================================
FILE: gopls/integration/govim/Dockerfile
================================================
# Copyright 2019 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# govim requires a more recent version of vim than is available in most
# distros, so we build from their base image.
FROM govim/govim:latest-vim
ARG GOVIM_REF

ENV GOPROXY=https://proxy.golang.org GOPATH=/go VIM_FLAVOR=vim
WORKDIR /src

# Clone govim. In order to use the go command for resolving latest, we download
# a redundant copy of govim to the build cache using `go mod download`.
RUN git clone https://github.com/govim/govim /src/govim && cd /src/govim && \
    git checkout $GOVIM_REF


================================================
FILE: gopls/integration/govim/README.md
================================================
# govim integration tests

Files in this directory configure Cloud Build to run [govim] integration tests
against a gopls binary built from source.

## Running on GCP

To run these integration tests in Cloud Build, use the following steps.  Here
we assume that `$PROJECT_ID` is a valid GCP project and `$BUCKET` is a cloud
storage bucket owned by that project.

- `cd` to the root directory of the tools project.
- (at least once per GCP project) Build the test harness:
```
$ gcloud builds submit \
	--project="${PROJECT_ID}" \
	--config=gopls/integration/govim/cloudbuild.harness.yaml
```
- Run the integration tests:
```
$ gcloud builds submit \
	--project="${PROJECT_ID}" \
	--config=gopls/integration/govim/cloudbuild.yaml \
	--substitutions=_RESULT_BUCKET="${BUCKET}"
```

## Fetching Artifacts

Assuming the artifacts bucket is world readable, you can fetch integration from
GCS. They are located at:

- logs: `https://storage.googleapis.com/${BUCKET}/log-${EVALUATION_ID}.txt`
- artifact tarball: `https://storage.googleapis.com/${BUCKET}/govim/${EVALUATION_ID}/artifacts.tar.gz`

The `artifacts.go` command can be used to fetch both artifacts using an
evaluation id.

## Running locally

Run `gopls/integration/govim/run_local.sh`. This may take a while the first
time it is run, as it will require building the test harness. This script
accepts two flags to modify its behavior:

**--sudo**: run docker with `sudo`
**--short**: run `go test -short`

[govim]: https://github.com/govim/govim


================================================
FILE: gopls/integration/govim/artifacts.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"flag"
	"fmt"
	"io"
	"net/http"
	"os"
	"path"
)

var bucket = flag.String("bucket", "golang-gopls_integration_tests", "GCS bucket holding test artifacts.")

const usage = `
artifacts [--bucket=<bucket ID>] <cloud build evaluation ID>

Fetch artifacts from an integration test run. Evaluation ID should be extracted
from the cloud build notification.

In order for this to work, the GCS bucket that artifacts were written to must
be publicly readable. By default, this fetches from the
golang-gopls_integration_tests bucket.
`

func main() {
	flag.Usage = func() {
		fmt.Fprint(flag.CommandLine.Output(), usage)
	}
	flag.Parse()
	if flag.NArg() != 1 {
		flag.Usage()
		os.Exit(2)
	}
	evalID := flag.Arg(0)
	logURL := fmt.Sprintf("https://storage.googleapis.com/%s/log-%s.txt", *bucket, evalID)
	if err := download(logURL); err != nil {
		fmt.Fprintf(os.Stderr, "downloading logs: %v", err)
	}
	tarURL := fmt.Sprintf("https://storage.googleapis.com/%s/govim/%s/artifacts.tar.gz", *bucket, evalID)
	if err := download(tarURL); err != nil {
		fmt.Fprintf(os.Stderr, "downloading artifact tarball: %v", err)
	}
}

func download(artifactURL string) error {
	name := path.Base(artifactURL)
	resp, err := http.Get(artifactURL)
	if err != nil {
		return fmt.Errorf("fetching from GCS: %v", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("got status code %d from GCS", resp.StatusCode)
	}
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return fmt.Errorf("reading result: %v", err)
	}
	if err := os.WriteFile(name, data, 0644); err != nil {
		return fmt.Errorf("writing artifact: %v", err)
	}
	return nil
}


================================================
FILE: gopls/integration/govim/cloudbuild.harness.yaml
================================================
# Copyright 2019 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# Build the govim test harness that will be used to run govim integration tests
# for gopls. See README.md for instructions on how to use this.
steps:
  - name: 'gcr.io/cloud-builders/docker'
    args: ['build',
      # To allow for breaking changes to this test harness, tag with a major
      # version number.
      '-t', 'gcr.io/$PROJECT_ID/govim-harness:latest',
      '-t', 'gcr.io/$PROJECT_ID/govim-harness:3',
      # It is assumed that this build is running from the root directory of the
      # tools repository.
      '-f', 'gopls/integration/govim/Dockerfile',
      # Use the integration test directory as build context: the test harness
      # doesn't actually require any local files.
      'gopls/integration/govim']
images:
  - gcr.io/$PROJECT_ID/govim-harness


================================================
FILE: gopls/integration/govim/cloudbuild.yaml
================================================
# Copyright 2019 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# Build gopls, and run the govim integration tests.  See README.md for
# instructions on how to use this.

substitutions:
  # This bucket must be owned by the GCP project executing the build. If
  # you are running this from your own project, override using --substitutions.
  _RESULT_BUCKET: 'golang-gopls_integration_tests'

steps:
  # Build gopls from source, to use with the govim integration tests.
  - name: 'golang:1.14'
    env: ['GOPROXY=https://proxy.golang.org']
    dir: 'gopls'
    args: ['go', 'build']

  # Run the tests. Note that the script in this step does not return the exit
  # code from `go test`, but rather saves it for use in the final step after
  # uploading artifacts.
  - name: 'gcr.io/$PROJECT_ID/govim-harness:3'
    dir: '/src/govim'
    volumes:
      - name: artifacts
        path: /artifacts
    env:
      - GOVIM_TESTSCRIPT_WORKDIR_ROOT=/artifacts
      - VIM_FLAVOR=vim
    args: ['/workspace/gopls/integration/govim/run_tests_for_cloudbuild.sh']

  # The govim tests produce a large number of artifacts; tarball/gzip to reduce
  # roundtrips and save space.
  - name: 'ubuntu'
    volumes:
      - name: artifacts
        path: /artifacts
    args: ['tar', '-czf', 'artifacts.tar.gz', '/artifacts']

  # Upload artifacts to GCS.
  - name: 'gcr.io/cloud-builders/gcloud'
    args: ['storage', 'cp', 'artifacts.tar.gz', 'gs://${_RESULT_BUCKET}/govim/${BUILD_ID}/artifacts.tar.gz']

  # Exit with the actual exit code of the integration tests.
  - name: 'ubuntu'
    args: ['bash', 'govim_test_result.sh']

# Write build logs to the same bucket as artifacts, so they can be more easily
# shared.
logsBucket: 'gs://${_RESULT_BUCKET}'


================================================
FILE: gopls/integration/govim/run_local.sh
================================================
#!/bin/bash -e

# Copyright 2019 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# Run govim integration tests against a local gopls.

usage() {
  cat <<EOUSAGE
Usage: $0 [--sudo] [--short] [--version (semver|latest)]

Args:
  --sudo     run docker with sudo
  --short    run `go test` with `-short`
  --version  run on the specific tagged govim version (or latest) rather
             than the default branch

Run govim tests against HEAD using local docker.
EOUSAGE
}

SUDO_IF_NEEDED=
TEST_SHORT=
DOCKERFILE=gopls/integration/govim/Dockerfile
GOVIM_REF=main
while [[ $# -gt 0 ]]; do
  case "$1" in
    "-h" | "--help" | "help")
      usage
      exit 0
      ;;
    "--sudo")
      SUDO_IF_NEEDED="sudo "
      shift
      ;;
    "--short")
      TEST_SHORT="-short"
      shift
      ;;
    "--version")
      if [[ -z "$2" ]]; then
        usage
        exit 1
      fi
      GOVIM_REF=$2
      if [[ "${GOVIM_REF}" == "latest" ]]; then
        TMPGOPATH=$(mktemp -d)
        trap "GOPATH=${TMPGOPATH} go clean -modcache && rm -r ${TMPGOPATH}" EXIT
        GOVIM_REF=$(GOPATH=${TMPGOPATH} go mod download -json \
          github.com/govim/govim@latest | jq -r .Version)
      fi
      shift 2
      ;;
    *)
      usage
      exit 1
  esac
done

# Find the tools root, so that this script can be run from any directory.
script_dir=$(dirname "$(readlink -f "$0")")
tools_dir=$(readlink -f "${script_dir}/../../..")

# Build gopls.
cd "${tools_dir}/gopls"
temp_gopls=$(mktemp -p "$PWD")
trap "rm -f \"${temp_gopls}\"" EXIT
# For consistency across environments, use golang docker to build rather than
# the local go command.
${SUDO_IF_NEEDED}docker run --rm -t \
  -v "${tools_dir}:/src/tools" \
  -w "/src/tools/gopls" \
  golang:rc \
  go build -o $(basename ${temp_gopls})

# Build the test harness. Here we are careful to pass in a very limited build
# context so as to optimize caching.
echo "Checking out govim@${GOVIM_REF}"
cd "${tools_dir}"
${SUDO_IF_NEEDED}docker build \
  --build-arg GOVIM_REF="${GOVIM_REF}" \
  -t gopls-govim-harness:${GOVIM_REF} \
  -f gopls/integration/govim/Dockerfile \
  gopls/integration/govim

# Run govim integration tests.
echo "running govim integration tests using ${temp_gopls}"
temp_gopls_name=$(basename "${temp_gopls}")
${SUDO_IF_NEEDED}docker run --rm -t \
  -v "${tools_dir}:/src/tools" \
  -w "/src/govim" \
  --ulimit memlock=-1:-1 \
  gopls-govim-harness:${GOVIM_REF} \
  go test ${TEST_SHORT} ./cmd/govim \
    -gopls "/src/tools/gopls/${temp_gopls_name}"


================================================
FILE: gopls/integration/govim/run_tests_for_cloudbuild.sh
================================================
#!/bin/bash

# Copyright 2020 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# This script runs govim integration tests but always succeeds, instead writing
# their result to a file so that any test failure can be deferred to a later
# build step. We do this so that we can capture govim test artifacts regardless
# of the test results.

# Substitute the locally built gopls binary for use in govim integration tests.
go test -short ./cmd/govim -gopls /workspace/gopls/gopls

# Stash the error, for use in a later build step.
echo "exit $?" > /workspace/govim_test_result.sh

# Clean up unnecessary artifacts. This is based on govim/_scripts/tidyUp.bash.
# Since we're fetching govim using the go command, we won't have this non-go
# source directory available to us.
if [[ -n "$GOVIM_TESTSCRIPT_WORKDIR_ROOT" ]]; then
  echo "Cleaning up build artifacts..."
  # Make artifacts writable so that rm -rf doesn't complain.
  chmod -R u+w "$GOVIM_TESTSCRIPT_WORKDIR_ROOT"

  # Remove directories we don't care about.
  find "$GOVIM_TESTSCRIPT_WORKDIR_ROOT" -type d \( -name .vim -o -name gopath \) -prune -exec rm -rf '{}' \;
fi


================================================
FILE: gopls/internal/analysis/deprecated/deprecated.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package deprecated

import (
	"bytes"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"strconv"
	"strings"

	_ "embed"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	internalastutil "golang.org/x/tools/internal/astutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "deprecated",
	Doc:              analyzerutil.MustExtractDoc(doc, "deprecated"),
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Run:              checkDeprecated,
	FactTypes:        []analysis.Fact{(*deprecationFact)(nil)},
	RunDespiteErrors: true,
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/deprecated",
}

// checkDeprecated is a simplified copy of staticcheck.CheckDeprecated.
func checkDeprecated(pass *analysis.Pass) (any, error) {
	inspector := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	deprs, err := collectDeprecatedNames(pass, inspector)
	if err != nil || (len(deprs.packages) == 0 && len(deprs.objects) == 0) {
		return nil, err
	}

	reportDeprecation := func(depr *deprecationFact, node ast.Node) {
		// TODO(hyangah): staticcheck.CheckDeprecated has more complex logic. Do we need it here?
		// TODO(hyangah): Scrub depr.Msg. depr.Msg may contain Go comments
		// markdown syntaxes but LSP diagnostics do not support markdown syntax.

		buf := new(bytes.Buffer)
		if err := format.Node(buf, pass.Fset, node); err != nil {
			// This shouldn't happen but let's be conservative.
			buf.Reset()
			buf.WriteString("declaration")
		}
		pass.ReportRangef(node, "%s is deprecated: %s", buf, depr.Msg)
	}

	nodeFilter := []ast.Node{(*ast.SelectorExpr)(nil)}
	inspector.Preorder(nodeFilter, func(node ast.Node) {
		// Caveat: this misses dot-imported objects
		sel, ok := node.(*ast.SelectorExpr)
		if !ok {
			return
		}

		obj := pass.TypesInfo.ObjectOf(sel.Sel)
		if fn, ok := obj.(*types.Func); ok {
			obj = fn.Origin()
		}
		if obj == nil || obj.Pkg() == nil {
			// skip invalid sel.Sel.
			return
		}

		if obj.Pkg() == pass.Pkg {
			// A package is allowed to use its own deprecated objects
			return
		}

		// A package "foo" has two related packages "foo_test" and "foo.test", for external tests and the package main
		// generated by 'go test' respectively. "foo_test" can import and use "foo", "foo.test" imports and uses "foo"
		// and "foo_test".

		if strings.TrimSuffix(pass.Pkg.Path(), "_test") == obj.Pkg().Path() {
			// foo_test (the external tests of foo) can use objects from foo.
			return
		}
		if strings.TrimSuffix(pass.Pkg.Path(), ".test") == obj.Pkg().Path() {
			// foo.test (the main package of foo's tests) can use objects from foo.
			return
		}
		if strings.TrimSuffix(pass.Pkg.Path(), ".test") == strings.TrimSuffix(obj.Pkg().Path(), "_test") {
			// foo.test (the main package of foo's tests) can use objects from foo's external tests.
			return
		}

		if depr, ok := deprs.objects[obj]; ok {
			reportDeprecation(depr, sel)
		}
	})

	for _, f := range pass.Files {
		for _, spec := range f.Imports {
			var imp *types.Package
			var obj types.Object
			if spec.Name != nil {
				obj = pass.TypesInfo.ObjectOf(spec.Name)
			} else {
				obj = pass.TypesInfo.Implicits[spec]
			}
			pkgName, ok := obj.(*types.PkgName)
			if !ok {
				continue
			}
			imp = pkgName.Imported()

			path, err := strconv.Unquote(spec.Path.Value)
			if err != nil {
				continue
			}
			pkgPath := pass.Pkg.Path()
			if strings.TrimSuffix(pkgPath, "_test") == path {
				// foo_test can import foo
				continue
			}
			if strings.TrimSuffix(pkgPath, ".test") == path {
				// foo.test can import foo
				continue
			}
			if strings.TrimSuffix(pkgPath, ".test") == strings.TrimSuffix(path, "_test") {
				// foo.test can import foo_test
				continue
			}
			if depr, ok := deprs.packages[imp]; ok {
				reportDeprecation(depr, spec.Path)
			}
		}
	}
	return nil, nil
}

type deprecationFact struct{ Msg string }

func (*deprecationFact) AFact()           {}
func (d *deprecationFact) String() string { return "Deprecated: " + d.Msg }

type deprecatedNames struct {
	objects  map[types.Object]*deprecationFact
	packages map[*types.Package]*deprecationFact
}

// collectDeprecatedNames collects deprecated identifiers and publishes
// them both as Facts and the return value. This is a simplified copy
// of staticcheck's fact_deprecated analyzer.
func collectDeprecatedNames(pass *analysis.Pass, ins *inspector.Inspector) (deprecatedNames, error) {
	doDocs := func(names []*ast.Ident, docs *ast.CommentGroup) {
		alt := strings.TrimPrefix(internalastutil.Deprecation(docs), "Deprecated: ")
		if alt == "" {
			return
		}

		for _, name := range names {
			obj := pass.TypesInfo.ObjectOf(name)
			pass.ExportObjectFact(obj, &deprecationFact{alt})
		}
	}

	// Is package deprecated?
	//
	// Don't mark package syscall as deprecated, even though
	// it is. A lot of people still use it for simple
	// constants like SIGKILL, and I am not comfortable
	// telling them to use x/sys for that.
	if pass.Pkg.Path() != "syscall" {
		for _, f := range pass.Files {
			if depr := internalastutil.Deprecation(f.Doc); depr != "" {
				pass.ExportPackageFact(&deprecationFact{depr})
				break
			}
		}
	}

	nodeFilter := []ast.Node{
		(*ast.GenDecl)(nil),
		(*ast.FuncDecl)(nil),
		(*ast.TypeSpec)(nil),
		(*ast.ValueSpec)(nil),
		(*ast.File)(nil),
		(*ast.StructType)(nil),
		(*ast.InterfaceType)(nil),
	}
	ins.Preorder(nodeFilter, func(node ast.Node) {
		var names []*ast.Ident
		var docs *ast.CommentGroup
		switch node := node.(type) {
		case *ast.GenDecl:
			switch node.Tok {
			case token.TYPE, token.CONST, token.VAR:
				docs = node.Doc
				for i := range node.Specs {
					switch n := node.Specs[i].(type) {
					case *ast.ValueSpec:
						names = append(names, n.Names...)
					case *ast.TypeSpec:
						names = append(names, n.Name)
					}
				}
			default:
				return
			}
		case *ast.FuncDecl:
			docs = node.Doc
			names = []*ast.Ident{node.Name}
		case *ast.TypeSpec:
			docs = node.Doc
			names = []*ast.Ident{node.Name}
		case *ast.ValueSpec:
			docs = node.Doc
			names = node.Names
		case *ast.StructType:
			for _, field := range node.Fields.List {
				doDocs(field.Names, field.Doc)
			}
		case *ast.InterfaceType:
			for _, field := range node.Methods.List {
				doDocs(field.Names, field.Doc)
			}
		}
		if docs != nil && len(names) > 0 {
			doDocs(names, docs)
		}
	})

	// Every identifier is potentially deprecated, so we will need
	// to look up facts a lot. Construct maps of all facts propagated
	// to this pass for fast lookup.
	out := deprecatedNames{
		objects:  map[types.Object]*deprecationFact{},
		packages: map[*types.Package]*deprecationFact{},
	}
	for _, fact := range pass.AllObjectFacts() {
		out.objects[fact.Object] = fact.Fact.(*deprecationFact)
	}
	for _, fact := range pass.AllPackageFacts() {
		out.packages[fact.Package] = fact.Fact.(*deprecationFact)
	}

	return out, nil
}


================================================
FILE: gopls/internal/analysis/deprecated/deprecated_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package deprecated

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, Analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/deprecated/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package deprecated defines an Analyzer that marks deprecated symbols and package imports.
//
// # Analyzer deprecated
//
// deprecated: check for use of deprecated identifiers
//
// The deprecated analyzer looks for deprecated symbols and package
// imports.
//
// See https://go.dev/wiki/Deprecated to learn about Go's convention
// for documenting and signaling deprecated identifiers.
package deprecated


================================================
FILE: gopls/internal/analysis/deprecated/testdata/src/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package usedeprecated

import "io/ioutil" // want "\"io/ioutil\" is deprecated: .*"

func x() {
	_, _ = ioutil.ReadFile("") // want "ioutil.ReadFile is deprecated: As of Go 1.16, .*"
	Legacy()                   // expect no deprecation notice.
}

// Legacy is deprecated.
//
// Deprecated: use X instead.
func Legacy() {} // want Legacy:"Deprecated: use X instead."


================================================
FILE: gopls/internal/analysis/deprecated/testdata/src/a/a_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package usedeprecated

import "testing"

func TestF(t *testing.T) {
	Legacy() // expect no deprecation notice.
	x()
}


================================================
FILE: gopls/internal/analysis/embeddirective/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package embeddirective defines an Analyzer that validates //go:embed directives.
// The analyzer defers fixes to its parent golang.Analyzer.
//
// # Analyzer embed
//
// embed: check //go:embed directive usage
//
// This analyzer checks that the embed package is imported if //go:embed
// directives are present, providing a suggested fix to add the import if
// it is missing.
//
// This analyzer also checks that //go:embed directives precede the
// declaration of a single variable.
package embeddirective


================================================
FILE: gopls/internal/analysis/embeddirective/embeddirective.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package embeddirective

import (
	_ "embed"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/refactor"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "embed",
	Doc:              analyzerutil.MustExtractDoc(doc, "embed"),
	Run:              run,
	RunDespiteErrors: true,
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/embeddirective",
}

func run(pass *analysis.Pass) (any, error) {
	for _, f := range pass.Files {
		comments := embedDirectiveComments(f)
		if len(comments) == 0 {
			continue // nothing to check
		}

		hasEmbedImport := false
		for _, imp := range f.Imports {
			if imp.Path.Value == `"embed"` {
				hasEmbedImport = true
				break
			}
		}

		for _, c := range comments {
			pos, end := c.Pos(), c.Pos()+token.Pos(len("//go:embed"))

			if !hasEmbedImport {
				// Add blank import of "embed".
				_, edits := refactor.AddImport(pass.TypesInfo, f, "_", "embed", "", c.Pos())
				if len(edits) > 0 {
					pass.Report(analysis.Diagnostic{
						Pos:     pos,
						End:     end,
						Message: `must import "embed" when using go:embed directives`,
						SuggestedFixes: []analysis.SuggestedFix{{
							Message:   `Add missing "embed" import`,
							TextEdits: edits,
						}},
					})
				}
			}

			var msg string
			spec := nextVarSpec(c, f)
			switch {
			case spec == nil:
				msg = `go:embed directives must precede a "var" declaration`
			case len(spec.Names) != 1:
				msg = "declarations following go:embed directives must define a single variable"
			case len(spec.Values) > 0:
				msg = "declarations following go:embed directives must not specify a value"
			case !embeddableType(pass.TypesInfo.Defs[spec.Names[0]]):
				msg = "declarations following go:embed directives must be of type string, []byte or embed.FS"
			}
			if msg != "" {
				pass.Report(analysis.Diagnostic{
					Pos:     pos,
					End:     end,
					Message: msg,
				})
			}
		}
	}
	return nil, nil
}

// embedDirectiveComments returns all comments in f that contains a //go:embed directive.
func embedDirectiveComments(f *ast.File) []*ast.Comment {
	comments := []*ast.Comment{}
	for _, cg := range f.Comments {
		for _, c := range cg.List {
			if strings.HasPrefix(c.Text, "//go:embed ") {
				comments = append(comments, c)
			}
		}
	}
	return comments
}

// nextVarSpec returns the ValueSpec for the variable declaration immediately following
// the go:embed comment, or nil if the next declaration is not a variable declaration.
func nextVarSpec(com *ast.Comment, f *ast.File) *ast.ValueSpec {
	// Embed directives must be followed by a declaration of one variable with no value.
	// There may be comments and empty lines between the directive and the declaration.
	var nextDecl ast.Decl
	for _, d := range f.Decls {
		if com.End() < d.End() {
			nextDecl = d
			break
		}
	}
	if nextDecl == nil || nextDecl.Pos() == token.NoPos {
		return nil
	}
	decl, ok := nextDecl.(*ast.GenDecl)
	if !ok {
		return nil
	}
	if decl.Tok != token.VAR {
		return nil
	}

	// var declarations can be both freestanding and blocks (with parenthesis).
	// Only the first variable spec following the directive is interesting.
	var nextSpec ast.Spec
	for _, s := range decl.Specs {
		if com.End() < s.End() {
			nextSpec = s
			break
		}
	}
	if nextSpec == nil {
		return nil
	}
	spec, ok := nextSpec.(*ast.ValueSpec)
	if !ok {
		// Invalid AST, but keep going.
		return nil
	}
	return spec
}

// embeddableType in go:embed directives are string, []byte or embed.FS.
func embeddableType(o types.Object) bool {
	if o == nil {
		return false
	}

	// For embed.FS the underlying type is an implementation detail.
	// As long as the named type resolves to embed.FS, it is OK.
	if named, ok := types.Unalias(o.Type()).(*types.Named); ok {
		obj := named.Obj()
		if obj.Pkg() != nil && obj.Pkg().Path() == "embed" && obj.Name() == "FS" {
			return true
		}
	}

	switch v := o.Type().Underlying().(type) {
	case *types.Basic:
		return types.Identical(v, types.Typ[types.String])
	case *types.Slice:
		return types.Identical(v.Elem(), types.Typ[types.Byte])
	}

	return false
}


================================================
FILE: gopls/internal/analysis/embeddirective/embeddirective_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package embeddirective

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, Analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/embeddirective/testdata/src/a/embedText
================================================
Hello World

================================================
FILE: gopls/internal/analysis/embeddirective/testdata/src/a/import_missing.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"fmt"
)

//go:embed embedtext // want "must import \"embed\" when using go:embed directives"
var s string

// This is main function
func main() {
	fmt.Println(s)
}


================================================
FILE: gopls/internal/analysis/embeddirective/testdata/src/a/import_missing.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	_ "embed"
	"fmt"
)

//go:embed embedtext // want "must import \"embed\" when using go:embed directives"
var s string

// This is main function
func main() {
	fmt.Println(s)
}


================================================
FILE: gopls/internal/analysis/embeddirective/testdata/src/a/import_present.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

// Misplaced, above imports.
//go:embed embedText // want "go:embed directives must precede a \"var\" declaration"

import (
	"embed"
	embedPkg "embed"
	"fmt"

	_ "embed"
)

//go:embed embedText // ok
var e1 string

// The analyzer does not check for many directives using the same var.
//
//go:embed embedText // ok
//go:embed embedText // ok
var e2 string

// Comments and blank lines between are OK. All types OK.
//
//go:embed embedText // ok
//
// foo

var e3 string

//go:embed embedText //ok
var e4 []byte

//go:embed embedText //ok
var e5 embed.FS

// Followed by wrong kind of decl.
//
//go:embed embedText // want "go:embed directives must precede a \"var\" declaration"
func fooFunc() {}

// Multiple variable specs.
//
//go:embed embedText // want "declarations following go:embed directives must define a single variable"
var e6, e7 []byte

// Specifying a value is not allowed.
//
//go:embed embedText // want "declarations following go:embed directives must not specify a value"
var e8 string = "foo"

// TODO: This should not be OK, misplaced according to compiler.
//
//go:embed embedText // ok
var (
	e9  string
	e10 string
)

// Type definition.
type fooType []byte

//go:embed embedText //ok
var e11 fooType

// Type alias.
type barType = string

//go:embed embedText //ok
var e12 barType

// Renamed embed package.

//go:embed embedText //ok
var e13 embedPkg.FS

// Renamed embed package alias.
type embedAlias = embedPkg.FS

//go:embed embedText //ok
var e14 embedAlias

// var blocks are OK as long as the variable following the directive is OK.
var (
	x, y, z string
	//go:embed embedText // ok
	e20     string
	q, r, t string
)

//go:embed embedText // want "go:embed directives must precede a \"var\" declaration"
var ()

// Incorrect types.

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e16 byte

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e17 []string

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e18 embed.Foo

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e19 foo.FS

type byteAlias byte

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e15 byteAlias

// A type declaration of embed.FS is not accepted by the compiler, in contrast to an alias.
type embedDecl embed.FS

//go:embed embedText // want `declarations following go:embed directives must be of type string, \[\]byte or embed.FS`
var e16 embedDecl

// This is main function
func main() {
	fmt.Println(s)
}

// No declaration following.
//go:embed embedText // want "go:embed directives must precede a \"var\" declaration"


================================================
FILE: gopls/internal/analysis/embeddirective/testdata/src/a/import_present_go120.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.20
// +build go1.20

package a

var (
	// Okay directive wise but the compiler will complain that
	// imports must appear before other declarations.
	//go:embed embedText // ok
	foo string
)

import (
	"fmt"

	_ "embed"
)

// This is main function
func main() {
	fmt.Println(s)
}


================================================
FILE: gopls/internal/analysis/fillreturns/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fillreturns defines an Analyzer that will attempt to
// automatically fill in a return statement that has missing
// values with zero value elements.
//
// # Analyzer fillreturns
//
// fillreturns: suggest fixes for errors due to an incorrect number of return values
//
// This checker provides suggested fixes for type errors of the
// type "wrong number of return values (want %d, got %d)". For example:
//
//	func m() (int, string, *bool, error) {
//		return
//	}
//
// will turn into
//
//	func m() (int, string, *bool, error) {
//		return 0, "", nil, nil
//	}
//
// This functionality is similar to https://github.com/sqs/goreturns.
package fillreturns


================================================
FILE: gopls/internal/analysis/fillreturns/fillreturns.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillreturns

import (
	"bytes"
	_ "embed"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"regexp"
	"slices"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/fuzzy"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "fillreturns",
	Doc:              analyzerutil.MustExtractDoc(doc, "fillreturns"),
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Run:              run,
	RunDespiteErrors: true,
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillreturns",
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	info := pass.TypesInfo

outer:
	for _, typeErr := range pass.TypeErrors {
		if !fixesError(typeErr) {
			continue // irrelevant type error
		}
		_, start, end, ok := typesinternal.ErrorCodeStartEnd(typeErr)
		if !ok {
			continue // no position information
		}
		curErr, ok := inspect.Root().FindByPos(start, end)
		if !ok {
			continue // can't find node
		}

		// Find cursor for enclosing return statement (which may be curErr itself).
		ret, curRet := cursorutil.FirstEnclosing[*ast.ReturnStmt](curErr)
		if ret == nil {
			continue // no enclosing return
		}

		// Skip if any return argument is a tuple-valued function call.
		for _, expr := range ret.Results {
			e, ok := expr.(*ast.CallExpr)
			if !ok {
				continue
			}
			if tup, ok := info.TypeOf(e).(*types.Tuple); ok && tup.Len() > 1 {
				continue outer
			}
		}

		// Get type of innermost enclosing function.
		var funcType *ast.FuncType
		curFunc, _ := enclosingFunc(curRet) // can't fail
		switch fn := curFunc.Node().(type) {
		case *ast.FuncLit:
			funcType = fn.Type
		case *ast.FuncDecl:
			funcType = fn.Type

			// Skip generic functions since type parameters don't have zero values.
			// TODO(rfindley): We should be able to handle this if the return
			// values are all concrete types.
			if funcType.TypeParams.NumFields() > 0 {
				continue
			}
		}
		if funcType.Results == nil {
			continue
		}

		// Duplicate the return values to track which values have been matched.
		remaining := make([]ast.Expr, len(ret.Results))
		copy(remaining, ret.Results)

		fixed := make([]ast.Expr, len(funcType.Results.List))

		// For each value in the return function declaration, find the leftmost element
		// in the return statement that has the desired type. If no such element exists,
		// fill in the missing value with the appropriate "zero" value.
		// Beware that type information may be incomplete.
		var retTyps []types.Type
		for _, ret := range funcType.Results.List {
			retTyp := info.TypeOf(ret.Type)
			if retTyp == nil {
				return nil, nil
			}
			retTyps = append(retTyps, retTyp)
		}

		file, _ := cursorutil.FirstEnclosing[*ast.File](curRet)
		matches := MatchingIdents(retTyps, file, ret.Pos(), info, pass.Pkg)
		qual := typesinternal.FileQualifier(file, pass.Pkg)
		for i, retTyp := range retTyps {
			var match ast.Expr
			var idx int
			for j, val := range remaining {
				if t := info.TypeOf(val); t == nil || !matchingTypes(t, retTyp) {
					continue
				}
				if !isZeroExpr(val) {
					match, idx = val, j
					break
				}
				// If the current match is a "zero" value, we keep searching in
				// case we find a non-"zero" value match. If we do not find a
				// non-"zero" value, we will use the "zero" value.
				match, idx = val, j
			}

			if match != nil {
				fixed[i] = match
				remaining = slices.Delete(remaining, idx, idx+1)
			} else {
				names, ok := matches[retTyp]
				if !ok {
					return nil, fmt.Errorf("invalid return type: %v", retTyp)
				}
				// Find the identifier most similar to the return type.
				// If no identifier matches the pattern, generate a zero value.
				if best := fuzzy.BestMatch(retTyp.String(), names); best != "" {
					fixed[i] = ast.NewIdent(best)
				} else if zero, isValid := typesinternal.ZeroExpr(retTyp, qual); isValid {
					fixed[i] = zero
				} else {
					return nil, nil
				}
			}
		}

		// Remove any non-matching "zero values" from the leftover values.
		var nonZeroRemaining []ast.Expr
		for _, expr := range remaining {
			if !isZeroExpr(expr) {
				nonZeroRemaining = append(nonZeroRemaining, expr)
			}
		}
		// Append leftover return values to end of new return statement.
		fixed = append(fixed, nonZeroRemaining...)

		newRet := &ast.ReturnStmt{
			Return:  ret.Pos(),
			Results: fixed,
		}

		// Convert the new return statement AST to text.
		var newBuf bytes.Buffer
		if err := format.Node(&newBuf, pass.Fset, newRet); err != nil {
			return nil, err
		}

		pass.Report(analysis.Diagnostic{
			Pos:     start,
			End:     end,
			Message: typeErr.Msg,
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Fill in return values",
				TextEdits: []analysis.TextEdit{{
					Pos:     ret.Pos(),
					End:     ret.End(),
					NewText: newBuf.Bytes(),
				}},
			}},
		})
	}
	return nil, nil
}

func matchingTypes(want, got types.Type) bool {
	if want == got || types.Identical(want, got) {
		return true
	}
	// Code segment to help check for untyped equality from (golang/go#32146).
	if rhs, ok := want.(*types.Basic); ok && rhs.Info()&types.IsUntyped > 0 {
		if lhs, ok := got.Underlying().(*types.Basic); ok {
			return rhs.Info()&types.IsConstType == lhs.Info()&types.IsConstType
		}
	}
	return types.AssignableTo(want, got) || types.ConvertibleTo(want, got)
}

// Error messages have changed across Go versions. These regexps capture recent
// incarnations.
//
// TODO(rfindley): once error codes are exported and exposed via go/packages,
// use error codes rather than string matching here.
var wrongReturnNumRegexes = []*regexp.Regexp{
	regexp.MustCompile(`wrong number of return values \(want (\d+), got (\d+)\)`),
	regexp.MustCompile(`too many return values`),
	regexp.MustCompile(`not enough return values`),
}

func fixesError(err types.Error) bool {
	msg := strings.TrimSpace(err.Msg)
	for _, rx := range wrongReturnNumRegexes {
		if rx.MatchString(msg) {
			return true
		}
	}
	return false
}

// enclosingFunc returns the cursor for the innermost Func{Decl,Lit}
// that encloses c, if any.
func enclosingFunc(c inspector.Cursor) (inspector.Cursor, bool) {
	return moreiters.First(c.Enclosing((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)))
}

// isZeroExpr uses simple syntactic heuristics to report whether expr
// is a obvious zero value, such as 0, "", nil, or false.
// It cannot do better without type information.
func isZeroExpr(expr ast.Expr) bool {
	switch e := expr.(type) {
	case *ast.BasicLit:
		return e.Value == "0" || e.Value == `""`
	case *ast.Ident:
		return e.Name == "nil" || e.Name == "false"
	default:
		return false
	}
}

// MatchingIdents finds the names of all identifiers in 'node' that match any of the given types.
// 'pos' represents the position at which the identifiers may be inserted. 'pos' must be within
// the scope of each of identifier we select. Otherwise, we will insert a variable at 'pos' that
// is unrecognized.
//
// This function is shared with the 'fillstruct' analyzer.
func MatchingIdents(typs []types.Type, node ast.Node, pos token.Pos, info *types.Info, pkg *types.Package) map[types.Type][]string {

	// Initialize matches to contain the variable types we are searching for.
	matches := make(map[types.Type][]string)
	for _, typ := range typs {
		if typ == nil {
			continue // TODO(adonovan): is this reachable?
		}
		matches[typ] = nil // create entry
	}

	seen := map[types.Object]struct{}{}
	ast.Inspect(node, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		// Prevent circular definitions. If 'pos' is within an assignment statement, do not
		// allow any identifiers in that assignment statement to be selected. Otherwise,
		// we could do the following, where 'x' satisfies the type of 'f0':
		//
		// x := fakeStruct{f0: x}
		//
		if assign, ok := n.(*ast.AssignStmt); ok && pos > assign.Pos() && pos <= assign.End() {
			return false
		}
		if n.End() > pos {
			return n.Pos() <= pos
		}
		ident, ok := n.(*ast.Ident)
		if !ok || ident.Name == "_" {
			return true
		}
		obj := info.Defs[ident]
		if obj == nil || obj.Type() == nil {
			return true
		}
		if _, ok := obj.(*types.TypeName); ok {
			return true
		}
		// Prevent duplicates in matches' values.
		if _, ok = seen[obj]; ok {
			return true
		}
		seen[obj] = struct{}{}
		// Find the scope for the given position. Then, check whether the object
		// exists within the scope.
		innerScope := pkg.Scope().Innermost(pos)
		if innerScope == nil {
			return true
		}
		_, foundObj := innerScope.LookupParent(ident.Name, pos)
		if foundObj != obj {
			return true
		}
		// The object must match one of the types that we are searching for.
		// TODO(adonovan): opt: use typeutil.Map?
		if names, ok := matches[obj.Type()]; ok {
			matches[obj.Type()] = append(names, ident.Name)
		} else {
			// If the object type does not exactly match
			// any of the target types, greedily find the first
			// target type that the object type can satisfy.
			for typ := range matches {
				if equivalentTypes(obj.Type(), typ) {
					matches[typ] = append(matches[typ], ident.Name)
				}
			}
		}
		return true
	})
	return matches
}

func equivalentTypes(want, got types.Type) bool {
	if types.Identical(want, got) {
		return true
	}
	// Code segment to help check for untyped equality from (golang/go#32146).
	if rhs, ok := want.(*types.Basic); ok && rhs.Info()&types.IsUntyped > 0 {
		if lhs, ok := got.Underlying().(*types.Basic); ok {
			return rhs.Info()&types.IsConstType == lhs.Info()&types.IsConstType
		}
	}
	return types.AssignableTo(want, got)
}


================================================
FILE: gopls/internal/analysis/fillreturns/fillreturns_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillreturns_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/fillreturns"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, fillreturns.Analyzer, "a", "typeparams")
}


================================================
FILE: gopls/internal/analysis/fillreturns/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillreturns

import (
	"errors"
	"go/ast"
	ast2 "go/ast"
	"io"
	"net/http"
	. "net/http"
	"net/url"
	"strconv"
)

type T struct{}
type T1 = T
type I interface{}
type I1 = I
type z func(string, http.Handler) error

func x() error {
	return errors.New("foo")
}

// The error messages below changed in 1.18; "return values" covers both forms.

func b() (string, int, error) {
	return "", errors.New("foo") // want "return values"
}

func c() (string, int, error) {
	return 7, errors.New("foo") // want "return values"
}

func d() (string, int, error) {
	return "", 7 // want "return values"
}

func e() (T, error, *bool) {
	return (z(http.ListenAndServe))("", nil) // want "return values"
}

func preserveLeft() (int, int, error) {
	return 1, errors.New("foo") // want "return values"
}

func matchValues() (int, error, string) {
	return errors.New("foo"), 3 // want "return values"
}

func preventDataOverwrite() (int, string) {
	return errors.New("foo") // want "return values"
}

func closure() (string, error) {
	_ = func() (int, error) {
		return // want "return values"
	}
	return // want "return values"
}

func basic() (uint8, uint16, uint32, uint64, int8, int16, int32, int64, float32, float64, complex64, complex128, byte, rune, uint, int, uintptr, string, bool, error) {
	return // want "return values"
}

func complex() (*int, []int, [2]int, map[int]int) {
	return // want "return values"
}

func structsAndInterfaces() (T, url.URL, T1, I, I1, io.Reader, Client, ast2.Stmt) {
	return // want "return values"
}

func m() (int, error) {
	if 1 == 2 {
		return // want "return values"
	} else if 1 == 3 {
		return errors.New("foo") // want "return values"
	} else {
		return 1 // want "return values"
	}
	return // want "return values"
}

func convertibleTypes() (ast2.Expr, int) {
	return &ast2.ArrayType{} // want "return values"
}

func assignableTypes() (map[string]int, int) {
	type X map[string]int
	var x X
	return x // want "return values"
}

func interfaceAndError() (I, int) {
	return errors.New("foo") // want "return values"
}

func funcOneReturn() (string, error) {
	return strconv.Itoa(1) // want "return values"
}

func funcMultipleReturn() (int, error, string) {
	return strconv.Atoi("1")
}

func localFuncMultipleReturn() (string, int, error, string) {
	return b()
}

func multipleUnused() (int, string, string, string) {
	return 3, 4, 5 // want "return values"
}

func gotTooMany() int {
	if true {
		return 0, "" // want "return values"
	} else {
		return 1, 0, nil // want "return values"
	}
	return 0, 5, false // want "return values"
}

func fillVars() (int, string, ast.Node, bool, error) {
	eint := 0
	s := "a"
	var t bool
	if true {
		err := errors.New("fail")
		return // want "return values"
	}
	n := ast.NewIdent("ident")
	int := 3
	var b bool
	return "" // want "return values"
}


================================================
FILE: gopls/internal/analysis/fillreturns/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillreturns

import (
	"errors"
	"go/ast"
	ast2 "go/ast"
	"io"
	"net/http"
	. "net/http"
	"net/url"
	"strconv"
)

type T struct{}
type T1 = T
type I interface{}
type I1 = I
type z func(string, http.Handler) error

func x() error {
	return errors.New("foo")
}

// The error messages below changed in 1.18; "return values" covers both forms.

func b() (string, int, error) {
	return "", 0, errors.New("foo") // want "return values"
}

func c() (string, int, error) {
	return "", 7, errors.New("foo") // want "return values"
}

func d() (string, int, error) {
	return "", 7, nil // want "return values"
}

func e() (T, error, *bool) {
	return T{}, (z(http.ListenAndServe))("", nil), nil // want "return values"
}

func preserveLeft() (int, int, error) {
	return 1, 0, errors.New("foo") // want "return values"
}

func matchValues() (int, error, string) {
	return 3, errors.New("foo"), "" // want "return values"
}

func preventDataOverwrite() (int, string) {
	return 0, "", errors.New("foo") // want "return values"
}

func closure() (string, error) {
	_ = func() (int, error) {
		return 0, nil // want "return values"
	}
	return "", nil // want "return values"
}

func basic() (uint8, uint16, uint32, uint64, int8, int16, int32, int64, float32, float64, complex64, complex128, byte, rune, uint, int, uintptr, string, bool, error) {
	return 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, "", false, nil // want "return values"
}

func complex() (*int, []int, [2]int, map[int]int) {
	return nil, nil, [2]int{}, nil // want "return values"
}

func structsAndInterfaces() (T, url.URL, T1, I, I1, io.Reader, Client, ast2.Stmt) {
	return T{}, url.URL{}, T1{}, nil, nil, nil, Client{}, nil // want "return values"
}

func m() (int, error) {
	if 1 == 2 {
		return 0, nil // want "return values"
	} else if 1 == 3 {
		return 0, errors.New("foo") // want "return values"
	} else {
		return 1, nil // want "return values"
	}
	return 0, nil // want "return values"
}

func convertibleTypes() (ast2.Expr, int) {
	return &ast2.ArrayType{}, 0 // want "return values"
}

func assignableTypes() (map[string]int, int) {
	type X map[string]int
	var x X
	return x, 0 // want "return values"
}

func interfaceAndError() (I, int) {
	return errors.New("foo"), 0 // want "return values"
}

func funcOneReturn() (string, error) {
	return strconv.Itoa(1), nil // want "return values"
}

func funcMultipleReturn() (int, error, string) {
	return strconv.Atoi("1")
}

func localFuncMultipleReturn() (string, int, error, string) {
	return b()
}

func multipleUnused() (int, string, string, string) {
	return 3, "", "", "", 4, 5 // want "return values"
}

func gotTooMany() int {
	if true {
		return 0 // want "return values"
	} else {
		return 1 // want "return values"
	}
	return 5 // want "return values"
}

func fillVars() (int, string, ast.Node, bool, error) {
	eint := 0
	s := "a"
	var t bool
	if true {
		err := errors.New("fail")
		return eint, s, nil, false, err // want "return values"
	}
	n := ast.NewIdent("ident")
	int := 3
	var b bool
	return int, "", n, b, nil // want "return values"
}


================================================
FILE: gopls/internal/analysis/fillreturns/testdata/src/typeparams/a.go
================================================
package fillreturns

func hello[T any]() int {
	return
}


================================================
FILE: gopls/internal/analysis/fillreturns/testdata/src/typeparams/a.go.golden
================================================
package fillreturns

func hello[T any]() int {
	return
}


================================================
FILE: gopls/internal/analysis/fillstruct/fillstruct.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fillstruct defines an Analyzer that automatically
// fills in a struct declaration with zero value elements for each field.
//
// The analyzer's diagnostic is merely a prompt.
// The actual fix is created by a separate direct call from gopls to
// the SuggestedFixes function.
// Tests of Analyzer.Run can be found in ./testdata/src.
// Tests of the SuggestedFixes logic live in ../../testdata/fillstruct.
package fillstruct

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/printer"
	"go/token"
	"go/types"
	"strings"
	"unicode"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/gopls/internal/analysis/fillreturns"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/fuzzy"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

// Diagnose computes diagnostics for fillable struct literals overlapping with
// the provided start and end position of file f.
//
// The diagnostic contains a lazy fix; the actual patch is computed
// (via the ApplyFix command) by a call to [SuggestedFix].
//
// If either start or end is invalid, the entire file is inspected.
func Diagnose(f *ast.File, start, end token.Pos, pkg *types.Package, info *types.Info) []analysis.Diagnostic {
	var diags []analysis.Diagnostic
	ast.Inspect(f, func(n ast.Node) bool {
		if n == nil {
			return true // pop
		}
		if start.IsValid() && n.End() < start || end.IsValid() && n.Pos() > end {
			return false // skip non-overlapping subtree
		}
		expr, ok := n.(*ast.CompositeLit)
		if !ok {
			return true
		}
		typ := info.TypeOf(expr)
		if typ == nil {
			return true
		}

		// Find reference to the type declaration of the struct being initialized.
		typ = typeparams.Deref(typ)
		tStruct, ok := typeparams.CoreType(typ).(*types.Struct)
		if !ok {
			return true
		}
		// Inv: typ is the possibly-named struct type.

		fieldCount := tStruct.NumFields()

		// Skip any struct that is already populated or that has no fields.
		if fieldCount == 0 || fieldCount == len(expr.Elts) {
			return true
		}

		// Are any fields in need of filling?
		var fillableFields []string
		for i := range fieldCount {
			field := tStruct.Field(i)
			// Ignore fields that are not accessible in the current package.
			if field.Pkg() != nil && field.Pkg() != pkg && !field.Exported() {
				continue
			}
			fillableFields = append(fillableFields, fmt.Sprintf("%s: %s", field.Name(), field.Type().String()))
		}
		if len(fillableFields) == 0 {
			return true
		}

		// Derive a name for the struct type.
		var name string
		if typ != tStruct {
			// named struct type (e.g. pkg.S[T])
			name = types.TypeString(typ, typesinternal.NameRelativeTo(pkg))
		} else {
			// anonymous struct type
			totalFields := len(fillableFields)
			const maxLen = 20
			// Find the index to cut off printing of fields.
			var i, fieldLen int
			for i = range fillableFields {
				if fieldLen > maxLen {
					break
				}
				fieldLen += len(fillableFields[i])
			}
			fillableFields = fillableFields[:i]
			if i < totalFields {
				fillableFields = append(fillableFields, "...")
			}
			name = fmt.Sprintf("anonymous struct{ %s }", strings.Join(fillableFields, ", "))
		}
		diags = append(diags, analysis.Diagnostic{
			Message:  fmt.Sprintf("%s literal has missing fields", name),
			Pos:      expr.Pos(),
			End:      expr.End(),
			Category: FixCategory,
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: fmt.Sprintf("Fill %s", name),
				// No TextEdits => computed later by gopls.
			}},
		})
		return true
	})

	return diags
}

const FixCategory = "fillstruct" // recognized by gopls ApplyFix

// SuggestedFix computes the suggested fix for the kinds of
// diagnostics produced by the Analyzer above.
func SuggestedFix(cpkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	var (
		file = pgf.File
		fset = cpkg.FileSet()
		pkg  = cpkg.Types()
		info = cpkg.TypesInfo()
		pos  = start // don't use end
	)
	cur, ok := pgf.Cursor().FindByPos(pos, pos)
	if !ok {
		return nil, nil, fmt.Errorf("no enclosing ast.Node")
	}
	expr, _ := cursorutil.FirstEnclosing[*ast.CompositeLit](cur)
	typ := info.TypeOf(expr)
	if typ == nil {
		return nil, nil, fmt.Errorf("no composite literal")
	}

	// Find reference to the type declaration of the struct being initialized.
	typ = typeparams.Deref(typ)
	tStruct, ok := typ.Underlying().(*types.Struct)
	if !ok {
		return nil, nil, fmt.Errorf("%s is not a (pointer to) struct type",
			types.TypeString(typ, typesinternal.NameRelativeTo(pkg)))
	}
	// Inv: typ is the possibly-named struct type.

	fieldCount := tStruct.NumFields()

	// Check which types have already been filled in. (we only want to fill in
	// the unfilled types, or else we'll blat user-supplied details)
	prefilledFields := map[string]ast.Expr{}
	var elts []ast.Expr
	for _, e := range expr.Elts {
		if kv, ok := e.(*ast.KeyValueExpr); ok {
			if key, ok := kv.Key.(*ast.Ident); ok {
				prefilledFields[key.Name] = kv.Value
				elts = append(elts, kv)
			}
		}
	}

	var fieldTyps []types.Type
	for i := range fieldCount {
		field := tStruct.Field(i)
		// Ignore fields that are not accessible in the current package.
		if field.Pkg() != nil && field.Pkg() != pkg && !field.Exported() {
			fieldTyps = append(fieldTyps, nil)
			continue
		}
		fieldTyps = append(fieldTyps, field.Type())
	}
	matches := fillreturns.MatchingIdents(fieldTyps, file, start, info, pkg)
	qual := typesinternal.FileQualifier(file, pkg)

	for i, fieldTyp := range fieldTyps {
		if fieldTyp == nil {
			continue // TODO(adonovan): is this reachable?
		}
		fieldName := tStruct.Field(i).Name()
		if _, ok := prefilledFields[fieldName]; ok {
			// We already stored these when looping over expr.Elt.
			// Want to preserve the original order of prefilled fields
			continue
		}

		kv := &ast.KeyValueExpr{
			Key: &ast.Ident{
				Name: fieldName,
			},
		}

		names, ok := matches[fieldTyp]
		if !ok {
			return nil, nil, fmt.Errorf("invalid struct field type: %v", fieldTyp)
		}

		// Find the name most similar to the field name.
		// If no name matches the pattern, generate a zero value.
		// NOTE: We currently match on the name of the field key rather than the field type.
		if best := fuzzy.BestMatch(fieldName, names); best != "" {
			kv.Value = ast.NewIdent(best)
		} else if expr, isValid := populateValue(fieldTyp, qual); isValid {
			kv.Value = expr
		} else {
			return nil, nil, nil // no fix to suggest
		}

		elts = append(elts, kv)
	}

	// If all of the struct's fields are unexported, we have nothing to do.
	if len(elts) == 0 {
		return nil, nil, fmt.Errorf("no elements to fill")
	}

	// Find the line on which the composite literal is declared.
	split := bytes.Split(pgf.Src, []byte("\n"))
	lineNumber := safetoken.StartPosition(fset, expr.Lbrace).Line
	firstLine := split[lineNumber-1] // lines are 1-indexed

	// Trim the whitespace from the left of the line, and use the index
	// to get the amount of whitespace on the left.
	trimmed := bytes.TrimLeftFunc(firstLine, unicode.IsSpace)
	index := bytes.Index(firstLine, trimmed)
	whitespace := firstLine[:index]

	// Write a new composite literal "_{...}" composed of all prefilled and new elements,
	// preserving existing formatting and comments.
	// An alternative would be to only format the new fields,
	// but by printing the entire composite literal, we ensure
	// that the result is gofmt'ed.
	var buf bytes.Buffer
	buf.WriteString("_{\n")
	fcmap := ast.NewCommentMap(fset, file, file.Comments)
	comments := fcmap.Filter(expr).Comments() // comments inside the expr, in source order
	for _, elt := range elts {
		// Print comments before the current elt
		for len(comments) > 0 && comments[0].Pos() < elt.Pos() {
			for _, co := range comments[0].List {
				fmt.Fprintln(&buf, co.Text)
			}
			comments = comments[1:]
		}

		// Print the current elt with comments
		eltcomments := fcmap.Filter(elt).Comments()
		if err := format.Node(&buf, fset, &printer.CommentedNode{Node: elt, Comments: eltcomments}); err != nil {
			return nil, nil, err
		}
		buf.WriteString(",")

		// Prune comments up to the end of the elt
		for len(comments) > 0 && comments[0].Pos() < elt.End() {
			comments = comments[1:]
		}

		// Write comments associated with the current elt that appear after it
		// printer.CommentedNode only prints comments inside the elt.
		for _, cg := range eltcomments {
			for _, co := range cg.List {
				if co.Pos() >= elt.End() {
					fmt.Fprintln(&buf, co.Text)
					if len(comments) > 0 {
						comments = comments[1:]
					}
				}
			}
		}
		buf.WriteString("\n")
	}
	buf.WriteString("}")
	formatted, err := format.Source(buf.Bytes())
	if err != nil {
		return nil, nil, err
	}

	sug := indent(formatted, whitespace)
	// Remove _
	idx := bytes.IndexByte(sug, '{') // cannot fail
	sug = sug[idx:]

	return fset, &analysis.SuggestedFix{
		TextEdits: []analysis.TextEdit{
			{
				Pos:     expr.Lbrace,
				End:     expr.Rbrace + token.Pos(len("}")),
				NewText: sug,
			},
		},
	}, nil
}

// indent works line by line through str, indenting (prefixing) each line with
// ind.
func indent(str, ind []byte) []byte {
	split := bytes.Split(str, []byte("\n"))
	newText := bytes.NewBuffer(nil)
	for i, s := range split {
		if len(s) == 0 {
			continue
		}
		// Don't add the extra indentation to the first line.
		if i != 0 {
			newText.Write(ind)
		}
		newText.Write(s)
		if i < len(split)-1 {
			newText.WriteByte('\n')
		}
	}
	return newText.Bytes()
}

// populateValue constructs an expression to fill the value of a struct field.
//
// When the type of a struct field is a basic literal or interface, we return
// default values. For other types, such as maps, slices, and channels, we create
// empty expressions such as []T{} or make(chan T) rather than using default values.
//
// The reasoning here is that users will call fillstruct with the intention of
// initializing the struct, in which case setting these fields to nil has no effect.
//
// If the input contains an invalid type, populateValue may panic or return
// expression that may not compile.
func populateValue(typ types.Type, qual types.Qualifier) (_ ast.Expr, isValid bool) {
	switch t := typ.(type) {
	case *types.TypeParam, *types.Interface, *types.Struct, *types.Basic:
		return typesinternal.ZeroExpr(t, qual)

	case *types.Alias, *types.Named:
		switch t.Underlying().(type) {
		// Avoid typesinternal.ZeroExpr here as we don't want to return nil.
		case *types.Map, *types.Slice:
			return &ast.CompositeLit{
				Type: typesinternal.TypeExpr(t, qual),
			}, true
		default:
			return typesinternal.ZeroExpr(t, qual)
		}

	// Avoid typesinternal.ZeroExpr here as we don't want to return nil.
	case *types.Map, *types.Slice:
		return &ast.CompositeLit{
			Type: typesinternal.TypeExpr(t, qual),
		}, true

	case *types.Array:
		return &ast.CompositeLit{
			Type: &ast.ArrayType{
				Elt: typesinternal.TypeExpr(t.Elem(), qual),
				Len: &ast.BasicLit{
					Kind: token.INT, Value: fmt.Sprintf("%v", t.Len()),
				},
			},
		}, true

	case *types.Chan:
		dir := ast.ChanDir(t.Dir())
		if t.Dir() == types.SendRecv {
			dir = ast.SEND | ast.RECV
		}
		return &ast.CallExpr{
			Fun: ast.NewIdent("make"),
			Args: []ast.Expr{
				&ast.ChanType{
					Dir:   dir,
					Value: typesinternal.TypeExpr(t.Elem(), qual),
				},
			},
		}, true

	case *types.Signature:
		return &ast.FuncLit{
			Type: typesinternal.TypeExpr(t, qual).(*ast.FuncType),
			// The body of the function literal contains a panic statement to
			// avoid type errors.
			Body: &ast.BlockStmt{
				List: []ast.Stmt{
					&ast.ExprStmt{
						X: &ast.CallExpr{
							Fun: ast.NewIdent("panic"),
							Args: []ast.Expr{
								&ast.BasicLit{
									Kind:  token.STRING,
									Value: `"TODO"`,
								},
							},
						},
					},
				},
			},
		}, true

	case *types.Pointer:
		switch tt := types.Unalias(t.Elem()).(type) {
		case *types.Basic:
			return &ast.CallExpr{
				Fun: &ast.Ident{
					Name: "new",
				},
				Args: []ast.Expr{
					&ast.Ident{
						Name: t.Elem().String(),
					},
				},
			}, true
		// Pointer to type parameter should return new(T) instead of &*new(T).
		case *types.TypeParam:
			return &ast.CallExpr{
				Fun: &ast.Ident{
					Name: "new",
				},
				Args: []ast.Expr{
					&ast.Ident{
						Name: tt.Obj().Name(),
					},
				},
			}, true
		default:
			// TODO(hxjiang): & prefix only works if populateValue returns a
			// composite literal T{} or the expression new(T).
			expr, isValid := populateValue(t.Elem(), qual)
			return &ast.UnaryExpr{
				Op: token.AND,
				X:  expr,
			}, isValid
		}
	}
	return nil, false
}


================================================
FILE: gopls/internal/analysis/fillstruct/fillstruct_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillstruct_test

import (
	"go/token"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/fillstruct"
)

// analyzer allows us to test the fillstruct code action using the analysistest
// harness. (fillstruct used to be a gopls analyzer.)
var analyzer = &analysis.Analyzer{
	Name: "fillstruct",
	Doc:  "test only",
	Run: func(pass *analysis.Pass) (any, error) {
		for _, f := range pass.Files {
			for _, diag := range fillstruct.Diagnose(f, token.NoPos, token.NoPos, pass.Pkg, pass.TypesInfo) {
				pass.Report(diag)
			}
		}
		return nil, nil
	},
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillstruct",
	RunDespiteErrors: true,
}

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, analyzer, "a", "typeparams")
}


================================================
FILE: gopls/internal/analysis/fillstruct/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillstruct

import (
	data "b"
	"go/ast"
	"go/token"
	"unsafe"
)

type emptyStruct struct{}

var _ = emptyStruct{}

type basicStruct struct {
	foo int
}

var _ = basicStruct{} // want `basicStruct literal has missing fields`

type twoArgStruct struct {
	foo int
	bar string
}

var _ = twoArgStruct{} // want `twoArgStruct literal has missing fields`

var _ = twoArgStruct{ // want `twoArgStruct literal has missing fields`
	bar: "bar",
}

type nestedStruct struct {
	bar   string
	basic basicStruct
}

var _ = nestedStruct{} // want `nestedStruct literal has missing fields`

var _ = data.B{} // want `fillstruct.B literal has missing fields`

type typedStruct struct {
	m  map[string]int
	s  []int
	c  chan int
	c1 <-chan int
	a  [2]string
}

var _ = typedStruct{} // want `typedStruct literal has missing fields`

type funStruct struct {
	fn func(i int) int
}

var _ = funStruct{} // want `funStruct literal has missing fields`

type funStructComplex struct {
	fn func(i int, s string) (string, int)
}

var _ = funStructComplex{} // want `funStructComplex literal has missing fields`

type funStructEmpty struct {
	fn func()
}

var _ = funStructEmpty{} // want `funStructEmpty literal has missing fields`

type Foo struct {
	A int
}

type Bar struct {
	X *Foo
	Y *Foo
}

var _ = Bar{} // want `Bar literal has missing fields`

type importedStruct struct {
	m  map[*ast.CompositeLit]ast.Field
	s  []ast.BadExpr
	a  [3]token.Token
	c  chan ast.EmptyStmt
	fn func(ast_decl ast.DeclStmt) ast.Ellipsis
	st ast.CompositeLit
}

var _ = importedStruct{} // want `importedStruct literal has missing fields`

type pointerBuiltinStruct struct {
	b *bool
	s *string
	i *int
}

var _ = pointerBuiltinStruct{} // want `pointerBuiltinStruct literal has missing fields`

var _ = []ast.BasicLit{
	{}, // want `ast.BasicLit literal has missing fields`
}

var _ = []ast.BasicLit{{}} // want "ast.BasicLit literal has missing fields"

type unsafeStruct struct {
	foo unsafe.Pointer
}

var _ = unsafeStruct{} // want `unsafeStruct literal has missing fields`


================================================
FILE: gopls/internal/analysis/fillstruct/testdata/src/b/b.go
================================================
package fillstruct

type B struct {
	ExportedInt   int
	unexportedInt int
}


================================================
FILE: gopls/internal/analysis/fillstruct/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillstruct

type emptyStruct[A any] struct{}

var _ = emptyStruct[int]{}

type basicStruct[T any] struct {
	foo T
}

var _ = basicStruct[int]{} // want `basicStruct\[int\] literal has missing fields`

type twoArgStruct[F, B any] struct {
	foo F
	bar B
}

var _ = twoArgStruct[string, int]{} // want `twoArgStruct\[string, int\] literal has missing fields`

var _ = twoArgStruct[int, string]{ // want `twoArgStruct\[int, string\] literal has missing fields`
	bar: "bar",
}

type nestedStruct struct {
	bar   string
	basic basicStruct[int]
}

var _ = nestedStruct{} // want "nestedStruct literal has missing fields"

func _[T any]() {
	type S struct{ t T }
	x := S{} // want "S"
	_ = x
}

func Test() {
	var tests = []struct {
		a, b, c, d, e, f, g, h, i, j, k, l, m, n, o, p string
	}{
		{}, // want "anonymous struct{ a: string, b: string, c: string, ... } literal has missing fields"
	}
	for _, test := range tests {
		_ = test
	}
}

func _[T twoArgStruct[int, int]]() {
	_ = T{} // want "T literal has missing fields"
}


================================================
FILE: gopls/internal/analysis/fillswitch/doc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fillswitch identifies switches with missing cases.
//
// It reports a diagnostic for each type switch or 'enum' switch that
// has missing cases, and suggests a fix to fill them in.
//
// The possible cases are: for a type switch, each accessible named
// type T or pointer *T that is assignable to the interface type; and
// for an 'enum' switch, each accessible named constant of the same
// type as the switch value.
//
// For an 'enum' switch, it will suggest cases for all possible values of the
// type.
//
//	type Suit int8
//	const (
//		 Spades Suit = iota
//		 Hearts
//		 Diamonds
//		 Clubs
//	)
//
//	var s Suit
//	switch s {
//	case Spades:
//	}
//
// It will report a diagnostic with a suggested fix to fill in the remaining
// cases:
//
//	var s Suit
//	switch s {
//	case Spades:
//	case Hearts:
//	case Diamonds:
//	case Clubs:
//	default:
//		 panic(fmt.Sprintf("unexpected Suit: %v", s))
//	}
//
// For a type switch, it will suggest cases for all types that implement the
// interface.
//
//	var stmt ast.Stmt
//	switch stmt.(type) {
//	case *ast.IfStmt:
//	}
//
// It will report a diagnostic with a suggested fix to fill in the remaining
// cases:
//
//	var stmt ast.Stmt
//	switch stmt.(type) {
//	case *ast.IfStmt:
//	case *ast.ForStmt:
//	case *ast.RangeStmt:
//	case *ast.AssignStmt:
//	case *ast.GoStmt:
//	...
//	default:
//		 panic(fmt.Sprintf("unexpected ast.Stmt: %T", stmt))
//	}
package fillswitch


================================================
FILE: gopls/internal/analysis/fillswitch/fillswitch.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillswitch

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/typesinternal"
)

// Diagnose computes diagnostics for switch statements with missing cases
// overlapping with the provided start and end position of file f.
//
// If either start or end is invalid, the entire file is inspected.
func Diagnose(f *ast.File, start, end token.Pos, pkg *types.Package, info *types.Info) []analysis.Diagnostic {
	var diags []analysis.Diagnostic
	ast.Inspect(f, func(n ast.Node) bool {
		if n == nil {
			return true // pop
		}
		if start.IsValid() && n.End() < start ||
			end.IsValid() && n.Pos() > end {
			return false // skip non-overlapping subtree
		}
		var fix *analysis.SuggestedFix
		switch n := n.(type) {
		case *ast.SwitchStmt:
			fix = suggestedFixSwitch(n, pkg, info)
		case *ast.TypeSwitchStmt:
			fix = suggestedFixTypeSwitch(n, pkg, info)
		}
		if fix != nil {
			diags = append(diags, analysis.Diagnostic{
				Message:        fix.Message,
				Pos:            n.Pos(),
				End:            n.Pos() + token.Pos(len("switch")),
				SuggestedFixes: []analysis.SuggestedFix{*fix},
			})
		}
		return true
	})

	return diags
}

func suggestedFixTypeSwitch(stmt *ast.TypeSwitchStmt, pkg *types.Package, info *types.Info) *analysis.SuggestedFix {
	if hasDefaultCase(stmt.Body) {
		return nil
	}

	namedType := namedTypeFromTypeSwitch(stmt, info)
	if namedType == nil {
		return nil
	}

	existingCases := caseTypes(stmt.Body, info)
	// Gather accessible package-level concrete types
	// that implement the switch interface type.
	scope := namedType.Obj().Pkg().Scope()
	var buf bytes.Buffer
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		if tname, ok := obj.(*types.TypeName); !ok || tname.IsAlias() {
			continue // not a defined type
		}

		if types.IsInterface(obj.Type()) {
			continue
		}

		samePkg := obj.Pkg() == pkg
		if !samePkg && !obj.Exported() {
			continue // inaccessible
		}

		var key caseType
		if types.AssignableTo(obj.Type(), namedType.Obj().Type()) {
			key.named = obj.Type().(*types.Named)
		} else if ptr := types.NewPointer(obj.Type()); types.AssignableTo(ptr, namedType.Obj().Type()) {
			key.named = obj.Type().(*types.Named)
			key.ptr = true
		}

		if key.named != nil {
			if existingCases[key] {
				continue
			}

			if buf.Len() > 0 {
				buf.WriteString("\t")
			}

			buf.WriteString("case ")
			if key.ptr {
				buf.WriteByte('*')
			}

			if p := key.named.Obj().Pkg(); p != pkg {
				// TODO: use the correct package name when the import is renamed
				buf.WriteString(p.Name())
				buf.WriteByte('.')
			}
			buf.WriteString(key.named.Obj().Name())
			buf.WriteString(":\n")
		}
	}

	if buf.Len() == 0 {
		return nil
	}

	switch assign := stmt.Assign.(type) {
	case *ast.AssignStmt:
		addDefaultCase(&buf, namedType, assign.Lhs[0])
	case *ast.ExprStmt:
		if assert, ok := assign.X.(*ast.TypeAssertExpr); ok {
			addDefaultCase(&buf, namedType, assert.X)
		}
	}

	return &analysis.SuggestedFix{
		Message: "Add cases for " + types.TypeString(namedType, typesinternal.NameRelativeTo(pkg)),
		TextEdits: []analysis.TextEdit{{
			Pos:     stmt.End() - token.Pos(len("}")),
			End:     stmt.End() - token.Pos(len("}")),
			NewText: buf.Bytes(),
		}},
	}
}

func suggestedFixSwitch(stmt *ast.SwitchStmt, pkg *types.Package, info *types.Info) *analysis.SuggestedFix {
	if hasDefaultCase(stmt.Body) {
		return nil
	}

	namedType, ok := info.TypeOf(stmt.Tag).(*types.Named)
	if !ok {
		return nil
	}

	existingCases := caseConsts(stmt.Body, info)
	// Gather accessible named constants of the same type as the switch value.
	scope := namedType.Obj().Pkg().Scope()
	var buf bytes.Buffer
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		if c, ok := obj.(*types.Const); ok &&
			(obj.Pkg() == pkg || obj.Exported()) && // accessible
			types.Identical(obj.Type(), namedType.Obj().Type()) &&
			!existingCases[c] {

			if buf.Len() > 0 {
				buf.WriteString("\t")
			}

			buf.WriteString("case ")
			if c.Pkg() != pkg {
				buf.WriteString(c.Pkg().Name())
				buf.WriteByte('.')
			}
			buf.WriteString(c.Name())
			buf.WriteString(":\n")
		}
	}

	if buf.Len() == 0 {
		return nil
	}

	addDefaultCase(&buf, namedType, stmt.Tag)

	return &analysis.SuggestedFix{
		Message: "Add cases for " + types.TypeString(namedType, typesinternal.NameRelativeTo(pkg)),
		TextEdits: []analysis.TextEdit{{
			Pos:     stmt.End() - token.Pos(len("}")),
			End:     stmt.End() - token.Pos(len("}")),
			NewText: buf.Bytes(),
		}},
	}
}

func addDefaultCase(buf *bytes.Buffer, named *types.Named, expr ast.Expr) {
	var dottedBuf bytes.Buffer
	// writeDotted emits a dotted path a.b.c.
	var writeDotted func(e ast.Expr) bool
	writeDotted = func(e ast.Expr) bool {
		switch e := e.(type) {
		case *ast.SelectorExpr:
			if !writeDotted(e.X) {
				return false
			}
			dottedBuf.WriteByte('.')
			dottedBuf.WriteString(e.Sel.Name)
			return true
		case *ast.Ident:
			dottedBuf.WriteString(e.Name)
			return true
		}
		return false
	}

	buf.WriteString("\tdefault:\n")
	typeName := fmt.Sprintf("%s.%s", named.Obj().Pkg().Name(), named.Obj().Name())
	if writeDotted(expr) {
		// Switch tag expression is a dotted path.
		// It is safe to re-evaluate it in the default case.
		format := fmt.Sprintf("unexpected %s: %%#v", typeName)
		fmt.Fprintf(buf, "\t\tpanic(fmt.Sprintf(%q, %s))\n\t", format, dottedBuf.String())
	} else {
		// Emit simpler message, without re-evaluating tag expression.
		fmt.Fprintf(buf, "\t\tpanic(%q)\n\t", "unexpected "+typeName)
	}
}

func namedTypeFromTypeSwitch(stmt *ast.TypeSwitchStmt, info *types.Info) *types.Named {
	switch assign := stmt.Assign.(type) {
	case *ast.ExprStmt:
		if typ, ok := assign.X.(*ast.TypeAssertExpr); ok {
			if named, ok := info.TypeOf(typ.X).(*types.Named); ok {
				return named
			}
		}

	case *ast.AssignStmt:
		if typ, ok := assign.Rhs[0].(*ast.TypeAssertExpr); ok {
			if named, ok := info.TypeOf(typ.X).(*types.Named); ok {
				return named
			}
		}
	}

	return nil
}

func hasDefaultCase(body *ast.BlockStmt) bool {
	for _, clause := range body.List {
		if len(clause.(*ast.CaseClause).List) == 0 {
			return true
		}
	}

	return false
}

func caseConsts(body *ast.BlockStmt, info *types.Info) map[*types.Const]bool {
	out := map[*types.Const]bool{}
	for _, stmt := range body.List {
		for _, e := range stmt.(*ast.CaseClause).List {
			if info.Types[e].Value == nil {
				continue // not a constant
			}

			if sel, ok := e.(*ast.SelectorExpr); ok {
				e = sel.Sel // replace pkg.C with C
			}

			if e, ok := e.(*ast.Ident); ok {
				if c, ok := info.Uses[e].(*types.Const); ok {
					out[c] = true
				}
			}
		}
	}

	return out
}

type caseType struct {
	named *types.Named
	ptr   bool
}

func caseTypes(body *ast.BlockStmt, info *types.Info) map[caseType]bool {
	out := map[caseType]bool{}
	for _, stmt := range body.List {
		for _, e := range stmt.(*ast.CaseClause).List {
			if tv, ok := info.Types[e]; ok && tv.IsType() {
				t := tv.Type
				ptr := false
				if p, ok := t.(*types.Pointer); ok {
					t = p.Elem()
					ptr = true
				}

				if named, ok := t.(*types.Named); ok {
					out[caseType{named, ptr}] = true
				}
			}
		}
	}

	return out
}


================================================
FILE: gopls/internal/analysis/fillswitch/fillswitch_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillswitch_test

import (
	"go/token"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/fillswitch"
)

// analyzer allows us to test the fillswitch code action using the analysistest
// harness.
var analyzer = &analysis.Analyzer{
	Name: "fillswitch",
	Doc:  "test only",
	Run: func(pass *analysis.Pass) (any, error) {
		for _, f := range pass.Files {
			for _, diag := range fillswitch.Diagnose(f, token.NoPos, token.NoPos, pass.Pkg, pass.TypesInfo) {
				pass.Report(diag)
			}
		}
		return nil, nil
	},
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillswitch",
	RunDespiteErrors: true,
}

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/fillswitch/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fillswitch

import altb "b"

type typeA int

const (
	typeAOne typeA = iota
	typeATwo
	typeAThree
)

func doSwitch() {
	var a typeA
	switch a { // want `Add cases for typeA`
	}

	switch a { // want `Add cases for typeA`
	case typeAOne:
	}

	switch a {
	case typeAOne:
	default:
	}

	switch a {
	case typeAOne:
	case typeATwo:
	case typeAThree:
	}

	var b altb.TypeB
	switch b { // want `Add cases for b.TypeB`
	case altb.TypeBOne:
	}
}

type notification interface {
	isNotification()
}

type notificationOne struct{}

func (notificationOne) isNotification() {}

type notificationTwo struct{}

func (notificationTwo) isNotification() {}

func doTypeSwitch() {
	var not notification
	switch not.(type) { // want `Add cases for notification`
	}

	switch not.(type) { // want `Add cases for notification`
	case notificationOne:
	}

	switch not.(type) {
	case notificationOne:
	case notificationTwo:
	}

	switch not.(type) {
	default:
	}

	var t data.ExportedInterface
	switch t {
	}
}


================================================
FILE: gopls/internal/analysis/fillswitch/testdata/src/b/b.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package b

type TypeB int

const (
	TypeBOne TypeB = iota
	TypeBTwo
	TypeBThree
)

type ExportedInterface interface {
	isExportedInterface()
}

type notExportedType struct{}

func (notExportedType) isExportedInterface() {}


================================================
FILE: gopls/internal/analysis/infertypeargs/infertypeargs.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package infertypeargs

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typeparams"
)

const Doc = `check for unnecessary type arguments in call expressions

Explicit type arguments may be omitted from call expressions if they can be
inferred from function arguments, or from other type arguments:

	func f[T any](T) {}
	
	func _() {
		f[string]("foo") // string could be inferred
	}
`

var Analyzer = &analysis.Analyzer{
	Name:     "infertypeargs",
	Doc:      Doc,
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/infertypeargs",
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	for _, diag := range diagnose(pass.Fset, inspect, token.NoPos, token.NoPos, pass.Pkg, pass.TypesInfo) {
		pass.Report(diag)
	}
	return nil, nil
}

// Diagnose reports diagnostics describing simplifications to type
// arguments overlapping with the provided start and end position.
//
// If start or end is token.NoPos, the corresponding bound is not checked
// (i.e. if both start and end are NoPos, all call expressions are considered).
func diagnose(fset *token.FileSet, inspect *inspector.Inspector, start, end token.Pos, pkg *types.Package, info *types.Info) []analysis.Diagnostic {
	var diags []analysis.Diagnostic

	nodeFilter := []ast.Node{(*ast.CallExpr)(nil)}
	inspect.Preorder(nodeFilter, func(node ast.Node) {
		call := node.(*ast.CallExpr)
		x, lbrack, indices, rbrack := typeparams.UnpackIndexExpr(call.Fun)
		ident := calledIdent(x)
		if ident == nil || len(indices) == 0 {
			return // no explicit args, nothing to do
		}

		if (start.IsValid() && call.End() < start) || (end.IsValid() && call.Pos() > end) {
			return // non-overlapping
		}

		// Confirm that instantiation actually occurred at this ident.
		idata, ok := info.Instances[ident]
		if !ok {
			return // something went wrong, but fail open
		}
		instance := idata.Type

		// Start removing argument expressions from the right, and check if we can
		// still infer the call expression.
		required := len(indices) // number of type expressions that are required
		for i := len(indices) - 1; i >= 0; i-- {
			var fun ast.Expr
			if i == 0 {
				// No longer an index expression: just use the parameterized operand.
				fun = x
			} else {
				fun = typeparams.PackIndexExpr(x, lbrack, indices[:i], indices[i-1].End())
			}
			newCall := &ast.CallExpr{
				Fun:      fun,
				Lparen:   call.Lparen,
				Args:     call.Args,
				Ellipsis: call.Ellipsis,
				Rparen:   call.Rparen,
			}
			info := &types.Info{
				Instances:    make(map[*ast.Ident]types.Instance),
				FileVersions: make(map[*ast.File]string),
			}
			if err := types.CheckExpr(fset, pkg, call.Pos(), newCall, info); err != nil {
				// Most likely inference failed.
				break
			}
			newIData := info.Instances[ident]
			newInstance := newIData.Type
			if !types.Identical(instance, newInstance) {
				// The inferred result type does not match the original result type, so
				// this simplification is not valid.
				break
			}
			required = i
		}
		if required < len(indices) {
			var s, e token.Pos
			var edit analysis.TextEdit
			if required == 0 {
				s, e = lbrack, rbrack+1 // erase the entire index
				edit = analysis.TextEdit{Pos: s, End: e}
			} else {
				s = indices[required].Pos()
				e = rbrack
				//  erase from end of last arg to include last comma & white-spaces
				edit = analysis.TextEdit{Pos: indices[required-1].End(), End: e}
			}
			// Recheck that our (narrower) fixes overlap with the requested range.
			if (start.IsValid() && e < start) || (end.IsValid() && s > end) {
				return // non-overlapping
			}
			diags = append(diags, analysis.Diagnostic{
				Pos:     s,
				End:     e,
				Message: "unnecessary type arguments",
				SuggestedFixes: []analysis.SuggestedFix{{
					Message:   "Simplify type arguments",
					TextEdits: []analysis.TextEdit{edit},
				}},
			})
		}
	})

	return diags
}

func calledIdent(x ast.Expr) *ast.Ident {
	switch x := x.(type) {
	case *ast.Ident:
		return x
	case *ast.SelectorExpr:
		return x.Sel
	}
	return nil
}


================================================
FILE: gopls/internal/analysis/infertypeargs/infertypeargs_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package infertypeargs_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/infertypeargs"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, infertypeargs.Analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/basic.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the infertyepargs checker.

package a

func f[T any](T) {}

func g[T any]() T { var x T; return x }

func h[P interface{ ~*T }, T any]() {}

func _() {
	f[string]("hello") // want "unnecessary type arguments"
	f[int](2)          // want "unnecessary type arguments"
	_ = g[int]()
	h[*int, int]() // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/basic.go.golden
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains tests for the infertyepargs checker.

package a

func f[T any](T) {}

func g[T any]() T { var x T; return x }

func h[P interface{ ~*T }, T any]() {}

func _() {
	f("hello") // want "unnecessary type arguments"
	f(2)       // want "unnecessary type arguments"
	_ = g[int]()
	h[*int]() // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/imported/imported.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imported

func F[T any](T) {}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/imported.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import "a/imported"

func _() {
	var x int
	imported.F[int](x) // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/imported.go.golden
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import "a/imported"

func _() {
	var x int
	imported.F(x) // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/notypechange.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// We should not suggest removing type arguments if doing so would change the
// resulting type.

package a

func id[T any](t T) T { return t }

var _ = id[int](1)        // want "unnecessary type arguments"
var _ = id[string]("foo") // want "unnecessary type arguments"
var _ = id[int64](2)

func pair[T any](t T) (T, T) { return t, t }

var _, _ = pair[int](3) // want "unnecessary type arguments"
var _, _ = pair[int64](3)

func noreturn[T any](t T) {}

func _() {
	noreturn[int64](4)
	noreturn[int](4) // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/infertypeargs/testdata/src/a/notypechange.go.golden
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// We should not suggest removing type arguments if doing so would change the
// resulting type.

package a

func id[T any](t T) T { return t }

var _ = id(1)     // want "unnecessary type arguments"
var _ = id("foo") // want "unnecessary type arguments"
var _ = id[int64](2)

func pair[T any](t T) (T, T) { return t, t }

var _, _ = pair(3) // want "unnecessary type arguments"
var _, _ = pair[int64](3)

func noreturn[T any](t T) {}

func _() {
	noreturn[int64](4)
	noreturn(4) // want "unnecessary type arguments"
}


================================================
FILE: gopls/internal/analysis/maprange/cmd/maprange/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The maprange command applies the golang.org/x/tools/gopls/internal/analysis/maprange
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/maprange"
)

func main() { singlechecker.Main(maprange.Analyzer) }


================================================
FILE: gopls/internal/analysis/maprange/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package maprange defines an Analyzer that checks for redundant use
// of the functions maps.Keys and maps.Values in "for" statements with
// "range" clauses.
//
// # Analyzer maprange
//
// maprange: checks for unnecessary calls to maps.Keys and maps.Values in range statements
//
// Consider a loop written like this:
//
//	for val := range maps.Values(m) {
//		fmt.Println(val)
//	}
//
// This should instead be written without the call to maps.Values:
//
//	for _, val := range m {
//		fmt.Println(val)
//	}
//
// golang.org/x/exp/maps returns slices for Keys/Values instead of iterators,
// but unnecessary calls should similarly be removed:
//
//	for _, key := range maps.Keys(m) {
//		fmt.Println(key)
//	}
//
// should be rewritten as:
//
//	for key := range m {
//		fmt.Println(key)
//	}
package maprange


================================================
FILE: gopls/internal/analysis/maprange/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The unusedfunc command runs the maprange analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/maprange"
)

func main() { singlechecker.Main(maprange.Analyzer) }


================================================
FILE: gopls/internal/analysis/maprange/maprange.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package maprange

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal/typeindex"
	"golang.org/x/tools/internal/versions"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "maprange",
	Doc:      analyzerutil.MustExtractDoc(doc, "maprange"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/maprange",
	Requires: []*analysis.Analyzer{typeindexanalyzer.Analyzer},
	Run:      run,
}

// This is a variable because the package name is different in Google's code base.
var xmaps = "golang.org/x/exp/maps"

func run(pass *analysis.Pass) (any, error) {
	switch pass.Pkg.Path() {
	case "maps", xmaps:
		// These packages know how to use their own APIs.
		return nil, nil
	}
	var (
		index       = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		mapsKeys    = index.Object("maps", "Keys")
		mapsValues  = index.Object("maps", "Values")
		xmapsKeys   = index.Object(xmaps, "Keys")
		xmapsValues = index.Object(xmaps, "Values")
	)
	for _, callee := range []types.Object{mapsKeys, mapsValues, xmapsKeys, xmapsValues} {
		for curCall := range index.Calls(callee) {
			if curCall.ParentEdgeKind() == edge.RangeStmt_X {
				analyzeRangeStmt(pass, callee, curCall)
			}
		}
	}
	return nil, nil
}

// analyzeRangeStmt analyzes range statements iterating over calls to maps.Keys
// or maps.Values (from the standard library "maps" or "golang.org/x/exp/maps").
//
// It reports a diagnostic with a suggested fix to simplify the loop by removing
// the unnecessary function call and adjusting range variables, if possible.
// For certain patterns involving x/exp/maps.Keys before Go 1.22, it reports
// a diagnostic about potential incorrect usage without a suggested fix.
// No diagnostic is reported if the range statement doesn't require changes.
func analyzeRangeStmt(pass *analysis.Pass, callee types.Object, curCall inspector.Cursor) {
	var (
		call      = curCall.Node().(*ast.CallExpr)
		rangeStmt = curCall.Parent().Node().(*ast.RangeStmt)
		pkg       = callee.Pkg().Path()
		fn        = callee.Name()
	)
	var edits []analysis.TextEdit

	// Check if the call to maps.Keys or maps.Values can be removed/replaced.
	// Example:
	//  for range maps.Keys(m)
	//            ^^^^^^^^^ removeCall
	//  for i, _ := range maps.Keys(m)
	//                    ^^^^^^^^^ replace with `len`
	//
	// If we have: for i, k := range maps.Keys(m) (only possible using x/exp/maps)
	//         or: for i, v = range maps.Values(m)
	// do not remove the call.
	removeCall := !isSet(rangeStmt.Key) || !isSet(rangeStmt.Value)
	replace := ""
	if pkg == xmaps && isSet(rangeStmt.Key) && rangeStmt.Value == nil {
		// If we have:   for i := range maps.Keys(m) (using x/exp/maps),
		// Replace with: for i := range len(m)
		// (This requires Go 1.22.)
		replace = "len"
		if !analyzerutil.FileUsesGoVersion(pass, astutil.EnclosingFile(curCall), versions.Go1_22) {
			pass.Report(analysis.Diagnostic{
				Pos:     call.Pos(),
				End:     call.End(),
				Message: fmt.Sprintf("likely incorrect use of %s.%s (returns a slice)", pkg, fn),
			})
			return
		}
	}
	if removeCall {
		edits = append(edits, analysis.TextEdit{
			Pos:     call.Fun.Pos(),
			End:     call.Fun.End(),
			NewText: []byte(replace)})
	}
	// Check if the key of the range statement should be removed.
	// Example:
	//  for _, k := range maps.Keys(m)
	//      ^^^ removeKey ^^^^^^^^^ removeCall
	removeKey := pkg == xmaps && fn == "Keys" && !isSet(rangeStmt.Key) && isSet(rangeStmt.Value)
	if removeKey {
		edits = append(edits, analysis.TextEdit{
			Pos: rangeStmt.Key.Pos(),
			End: rangeStmt.Value.Pos(),
		})
	}
	// Check if a key should be inserted to the range statement.
	// Example:
	//  for _, v := range maps.Values(m)
	//      ^^^ addKey    ^^^^^^^^^^^ removeCall
	addKey := pkg == "maps" && fn == "Values" && isSet(rangeStmt.Key)
	if addKey {
		edits = append(edits, analysis.TextEdit{
			Pos:     rangeStmt.Key.Pos(),
			End:     rangeStmt.Key.Pos(),
			NewText: []byte("_, "),
		})
	}

	if len(edits) > 0 {
		pass.Report(analysis.Diagnostic{
			Pos:     call.Pos(),
			End:     call.End(),
			Message: fmt.Sprintf("unnecessary and inefficient call of %s.%s", pkg, fn),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   fmt.Sprintf("Remove unnecessary call to %s.%s", pkg, fn),
				TextEdits: edits,
			}},
		})
	}
}

// isSet reports whether an ast.Expr is a non-nil expression that is not the blank identifier.
func isSet(expr ast.Expr) bool {
	ident, ok := expr.(*ast.Ident)
	return expr != nil && (!ok || ident.Name != "_")
}


================================================
FILE: gopls/internal/analysis/maprange/maprange_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package maprange_test

import (
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/maprange"
	"golang.org/x/tools/internal/testfiles"
	"path/filepath"
	"testing"
)

func TestBasic(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "basic.txtar"))
	analysistest.RunWithSuggestedFixes(t, dir, maprange.Analyzer, "maprange")
}

func TestOld(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "old.txtar"))
	analysistest.RunWithSuggestedFixes(t, dir, maprange.Analyzer, "maprange")
}


================================================
FILE: gopls/internal/analysis/maprange/testdata/basic.txtar
================================================
Test of fixing redundant calls to maps.Keys and maps.Values
(both stdlib "maps" and "golang.org/x/exp/maps") for Go 1.24.

-- go.mod --
module maprange

require golang.org/x/exp v0.0.0

replace golang.org/x/exp => ./exp

go 1.24

-- basic.go --
package basic

import "maps"

func _() {
	m := make(map[int]int)

	for range maps.Keys(m) { // want `unnecessary and inefficient call of maps.Keys`
	}

	for range maps.Values(m) { // want `unnecessary and inefficient call of maps.Values`
	}

	var x struct {
		Map map[int]int
	}
	x.Map = make(map[int]int)
	for x.Map[1] = range maps.Keys(m) { // want `unnecessary and inefficient call of maps.Keys`
	}

	for x.Map[2] = range maps.Values(m) { // want `unnecessary and inefficient call of maps.Values`
	}

	for k := range maps.Keys(m) { // want `unnecessary and inefficient call of maps.Keys`
		_ = k
	}

	for v := range maps.Values(m) { // want `unnecessary and inefficient call of maps.Values`
		_ = v
	}

	for range maps.Keys(x.Map) { // want `unnecessary and inefficient call of maps.Keys`
	}

	for /* comment */ k := range /* comment */ maps.Keys(/* comment */ m) { // want `unnecessary and inefficient call of maps.Keys`
		_ = k
	}
}

-- basic.go.golden --
package basic

func _() {
	m := make(map[int]int)

	for range m { // want `unnecessary and inefficient call of maps.Keys`
	}

	for range m { // want `unnecessary and inefficient call of maps.Values`
	}

	var x struct {
		Map map[int]int
	}
	x.Map = make(map[int]int)
	for x.Map[1] = range m { // want `unnecessary and inefficient call of maps.Keys`
	}

	for _, x.Map[2] = range m { // want `unnecessary and inefficient call of maps.Values`
	}

	for k := range m { // want `unnecessary and inefficient call of maps.Keys`
		_ = k
	}

	for _, v := range m { // want `unnecessary and inefficient call of maps.Values`
		_ = v
	}

	for range x.Map { // want `unnecessary and inefficient call of maps.Keys`
	}

	for /* comment */ k := range /* comment */ /* comment */ m { // want `unnecessary and inefficient call of maps.Keys`
		_ = k
	}
}

-- xmaps.go --
package basic

import "golang.org/x/exp/maps"

func _() {
	m := make(map[int]int)

	for range maps.Keys(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for range maps.Values(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}

	for i := range maps.Values(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
		_ = i
	}

	var x struct {
		Map map[int]int
	}
	x.Map = make(map[int]int)
	for _, x.Map[1] = range maps.Keys(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for _, x.Map[2] = range maps.Values(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}

	for _, k := range maps.Keys(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
		_ = k
	}

	for _, v := range maps.Values(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
		_ = v
	}

	for range maps.Keys(x.Map) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for i, k := range maps.Keys(m) { // ok: this can't be straightforwardly rewritten
		_, _ = i, k
	}

	for _, _ = range maps.Values(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}
}

-- xmaps.go.golden --
package basic

import "golang.org/x/exp/maps"

func _() {
	m := make(map[int]int)

	for range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}

	for i := range len(m) { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
		_ = i
	}

	var x struct {
		Map map[int]int
	}
	x.Map = make(map[int]int)
	for x.Map[1] = range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for _, x.Map[2] = range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}

	for k := range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
		_ = k
	}

	for _, v := range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
		_ = v
	}

	for range x.Map { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Keys`
	}

	for i, k := range maps.Keys(m) { // ok: this can't be straightforwardly rewritten
		_, _ = i, k
	}

	for _, _ = range m { // want `unnecessary and inefficient call of golang.org/x/exp/maps.Values`
	}
}

-- exp/go.mod --
module golang.org/x/exp

go 1.24

-- exp/maps/maps.go --
package maps

func Keys[M ~map[K]V, K comparable, V any](m M) []K {
	r := make([]K, 0, len(m))
	for k := range m {
		r = append(r, k)
	}
	return r
}

func Values[M ~map[K]V, K comparable, V any](m M) []V {
	r := make([]V, 0, len(m))
	for _, v := range m {
		r = append(r, v)
	}
	return r
}

================================================
FILE: gopls/internal/analysis/maprange/testdata/old.txtar
================================================
Test of fixing redundant calls to maps.Keys and maps.Values
(both stdlib "maps" and "golang.org/x/exp/maps") for Go 1.21,
before range over int made suggesting a fix for a rare case easier.

-- go.mod --
module maprange

require golang.org/x/exp v0.0.0

replace golang.org/x/exp => ./exp

go 1.21

-- old.go --
package old

import "golang.org/x/exp/maps"

func _() {
	m := make(map[int]int)

	for i := range maps.Keys(m) { // want `likely incorrect use of golang.org/x/exp/maps.Keys \(returns a slice\)`
		_ = i
	}
}

-- old.go.golden --
package old

import "golang.org/x/exp/maps"

func _() {
	m := make(map[int]int)

	for i := range maps.Keys(m) { // want `likely incorrect use of golang.org/x/exp/maps.Keys \(returns a slice\)`
		_ = i
	}
}

-- exp/go.mod --
module golang.org/x/exp

go 1.21

-- exp/maps/maps.go --
package maps

func Keys[M ~map[K]V, K comparable, V any](m M) []K {
	r := make([]K, 0, len(m))
	for k := range m {
		r = append(r, k)
	}
	return r
}

func Values[M ~map[K]V, K comparable, V any](m M) []V {
	r := make([]V, 0, len(m))
	for _, v := range m {
		r = append(r, v)
	}
	return r
}

================================================
FILE: gopls/internal/analysis/modernize/cmd/modernize/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The modernize command suggests (or, with -fix, applies) fixes that
// clarify Go code by using more modern features.
//
// See [golang.org/x/tools/go/analysis/passes/modernize] for details.
//
// Deprecated: use 'go run
// golang.org/x/tools/go/analysis/passes/modernize/cmd/modernize' instead. In
// due course the modernizer suite will be accessed through "go fix";
// see https://go.dev/issue/71859.
package main

import (
	"golang.org/x/tools/go/analysis/multichecker"
	"golang.org/x/tools/go/analysis/passes/modernize"
)

func main() { multichecker.Main(modernize.Suite...) }


================================================
FILE: gopls/internal/analysis/nonewvars/doc.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nonewvars defines an Analyzer that applies suggested fixes
// to errors of the type "no new variables on left side of :=".
//
// # Analyzer nonewvars
//
// nonewvars: suggested fixes for "no new vars on left side of :="
//
// This checker provides suggested fixes for type errors of the
// type "no new vars on left side of :=". For example:
//
//	z := 1
//	z := 2
//
// will turn into
//
//	z := 1
//	z = 2
package nonewvars


================================================
FILE: gopls/internal/analysis/nonewvars/nonewvars.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package nonewvars defines an Analyzer that applies suggested fixes
// to errors of the type "no new variables on left side of :=".
package nonewvars

import (
	_ "embed"
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "nonewvars",
	Doc:              analyzerutil.MustExtractDoc(doc, "nonewvars"),
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Run:              run,
	RunDespiteErrors: true,
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/nonewvars",
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	for _, typeErr := range pass.TypeErrors {
		if typeErr.Msg != "no new variables on left side of :=" {
			continue // irrelevant error
		}
		_, start, end, ok := typesinternal.ErrorCodeStartEnd(typeErr)
		if !ok {
			continue // can't get position info
		}
		curErr, ok := inspect.Root().FindByPos(start, end)
		if !ok {
			continue // can't find errant node
		}

		// Find enclosing assignment (which may be curErr itself).
		assign, _ := cursorutil.FirstEnclosing[*ast.AssignStmt](curErr)
		if assign == nil {
			continue // no enclosing assignment
		}
		if assign.Tok != token.DEFINE {
			continue // not a := statement
		}

		pass.Report(analysis.Diagnostic{
			Pos:     assign.TokPos,
			End:     assign.TokPos + token.Pos(len(":=")),
			Message: typeErr.Msg,
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Change ':=' to '='",
				TextEdits: []analysis.TextEdit{{
					Pos: assign.TokPos,
					End: assign.TokPos + token.Pos(len(":")),
				}},
			}},
		})
	}
	return nil, nil
}


================================================
FILE: gopls/internal/analysis/nonewvars/nonewvars_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nonewvars_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/nonewvars"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, nonewvars.Analyzer, "a", "typeparams")
}


================================================
FILE: gopls/internal/analysis/nonewvars/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nonewvars

import "log"

func x() {
	z := 1
	z := 2 // want "no new variables on left side of :="

	_, z := 3, 100 // want "no new variables on left side of :="

	log.Println(z)
}


================================================
FILE: gopls/internal/analysis/nonewvars/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package nonewvars

import "log"

func x() {
	z := 1
	z = 2 // want "no new variables on left side of :="

	_, z = 3, 100 // want "no new variables on left side of :="

	log.Println(z)
}


================================================
FILE: gopls/internal/analysis/nonewvars/testdata/src/typeparams/a.go
================================================
package nonewvars

func hello[T any]() int {
	var z T
	z := 1 // want "no new variables on left side of :="
}


================================================
FILE: gopls/internal/analysis/nonewvars/testdata/src/typeparams/a.go.golden
================================================
package nonewvars

func hello[T any]() int {
	var z T
	z = 1 // want "no new variables on left side of :="
}


================================================
FILE: gopls/internal/analysis/noresultvalues/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package noresultvalues defines an Analyzer that applies suggested fixes
// to errors of the type "no result values expected".
//
// # Analyzer noresultvalues
//
// noresultvalues: suggested fixes for unexpected return values
//
// This checker provides suggested fixes for type errors of the
// type "no result values expected" or "too many return values".
// For example:
//
//	func z() { return nil }
//
// will turn into
//
//	func z() { return }
package noresultvalues


================================================
FILE: gopls/internal/analysis/noresultvalues/noresultvalues.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package noresultvalues

import (
	"go/ast"
	"go/token"
	"strings"

	_ "embed"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:             "noresultvalues",
	Doc:              analyzerutil.MustExtractDoc(doc, "noresultvalues"),
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Run:              run,
	RunDespiteErrors: true,
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/noresultvalues",
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	for _, typErr := range pass.TypeErrors {
		if !fixesError(typErr.Msg) {
			continue // irrelevant error
		}
		_, start, end, ok := typesinternal.ErrorCodeStartEnd(typErr)
		if !ok {
			continue // can't get position info
		}
		curErr, ok := inspect.Root().FindByPos(start, end)
		if !ok {
			continue // can't find errant node
		}
		// Find first enclosing return statement, if any.
		ret, _ := cursorutil.FirstEnclosing[*ast.ReturnStmt](curErr)
		if ret != nil {
			pass.Report(analysis.Diagnostic{
				Pos:     start,
				End:     end,
				Message: typErr.Msg,
				SuggestedFixes: []analysis.SuggestedFix{{
					Message: "Delete return values",
					TextEdits: []analysis.TextEdit{{
						Pos: ret.Pos() + token.Pos(len("return")),
						End: ret.End(),
					}},
				}},
			})
		}
	}
	return nil, nil
}

func fixesError(msg string) bool {
	return msg == "no result values expected" ||
		strings.HasPrefix(msg, "too many return values") && strings.Contains(msg, "want ()")
}


================================================
FILE: gopls/internal/analysis/noresultvalues/noresultvalues_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package noresultvalues_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/noresultvalues"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, noresultvalues.Analyzer, "a", "typeparams")
}


================================================
FILE: gopls/internal/analysis/noresultvalues/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package noresultvalues

func x() { return nil } // want `no result values expected|too many return values`

func y() { return nil, "hello" } // want `no result values expected|too many return values`


================================================
FILE: gopls/internal/analysis/noresultvalues/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package noresultvalues

func x() { return } // want `no result values expected|too many return values`

func y() { return } // want `no result values expected|too many return values`


================================================
FILE: gopls/internal/analysis/noresultvalues/testdata/src/typeparams/a.go
================================================
package noresult

func hello[T any]() {
	var z T
	return z // want `no result values expected|too many return values`
}


================================================
FILE: gopls/internal/analysis/noresultvalues/testdata/src/typeparams/a.go.golden
================================================
package noresult

func hello[T any]() {
	var z T
	return // want `no result values expected|too many return values`
}


================================================
FILE: gopls/internal/analysis/recursiveiter/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package recursiveiter defines an Analyzer that checks for mistakes
// in iterators for recursive data structures.
//
// # Analyzer recursiveiter
//
// recursiveiter: check for inefficient recursive iterators
//
// This analyzer reports when a function that returns an iterator
// (iter.Seq or iter.Seq2) calls itself as the operand of a range
// statement, as this is inefficient.
//
// When implementing an iterator (e.g. iter.Seq[T]) for a recursive
// data type such as a tree or linked list, it is tempting to
// recursively range over the iterator for each child element.
//
// Here's an example of a naive iterator over a binary tree:
//
//	type tree struct {
//		value       int
//		left, right *tree
//	}
//
//	func (t *tree) All() iter.Seq[int] {
//		return func(yield func(int) bool) {
//			if t != nil {
//				for elem := range t.left.All() { // "inefficient recursive iterator"
//					if !yield(elem) {
//						return
//					}
//				}
//				if !yield(t.value) {
//					return
//				}
//				for elem := range t.right.All() { // "inefficient recursive iterator"
//					if !yield(elem) {
//						return
//					}
//				}
//			}
//		}
//	}
//
// Though it correctly enumerates the elements of the tree, it hides a
// significant performance problem--two, in fact. Consider a balanced
// tree of N nodes. Iterating the root node will cause All to be
// called once on every node of the tree. This results in a chain of
// nested active range-over-func statements when yield(t.value) is
// called on a leaf node.
//
// The first performance problem is that each range-over-func
// statement must typically heap-allocate a variable, so iteration of
// the tree allocates as many variables as there are elements in the
// tree, for a total of O(N) allocations, all unnecessary.
//
// The second problem is that each call to yield for a leaf of the
// tree causes each of the enclosing range loops to receive a value,
// which they then immediately pass on to their respective yield
// function. This results in a chain of log(N) dynamic yield calls per
// element, a total of O(N*log N) dynamic calls overall, when only
// O(N) are necessary.
//
// A better implementation strategy for recursive iterators is to
// first define the "every" operator for your recursive data type,
// where every(f) reports whether an arbitrary predicate f(x) is true
// for every element x in the data type. For our tree, the every
// function would be:
//
//	func (t *tree) every(f func(int) bool) bool {
//		return t == nil ||
//			t.left.every(f) && f(t.value) && t.right.every(f)
//	}
//
// For example, this use of the every operator prints whether every
// element in the tree is an even number:
//
//	even := func(x int) bool { return x&1 == 0 }
//	println(t.every(even))
//
// Then the iterator can be simply expressed as a trivial wrapper
// around the every operator:
//
//	func (t *tree) All() iter.Seq[int] {
//		return func(yield func(int) bool) {
//			_ = t.every(yield)
//		}
//	}
//
// In effect, tree.All computes whether yield returns true for each
// element, short-circuiting if it ever returns false, then discards
// the final boolean result.
//
// This has much better performance characteristics: it makes one
// dynamic call per element of the tree, and it doesn't heap-allocate
// anything. It is also clearer.
package recursiveiter


================================================
FILE: gopls/internal/analysis/recursiveiter/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The recursiveiter command applies the yield analyzer to the
// specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/recursiveiter"
)

func main() { singlechecker.Main(recursiveiter.Analyzer) }


================================================
FILE: gopls/internal/analysis/recursiveiter/recursiveiter.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package recursiveiter

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "recursiveiter",
	Doc:      analyzerutil.MustExtractDoc(doc, "recursiveiter"),
	Requires: []*analysis.Analyzer{inspect.Analyzer, typeindexanalyzer.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/recursiveiter",
}

func run(pass *analysis.Pass) (any, error) {
	var (
		inspector = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		index     = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
		info      = pass.TypesInfo
		iterSeq   = index.Object("iter", "Seq")
		iterSeq2  = index.Object("iter", "Seq2")
	)
	if iterSeq == nil || iterSeq2 == nil {
		return nil, nil // fast path: no iterators
	}

	// Search for a function or method f that returns an iter.Seq
	// or Seq2 and calls itself recursively within a range stmt:
	//
	// func f(...) iter.Seq[E] {
	//	return func(yield func(E) bool) {
	//		...
	//		for range f(...) { ... }
	// 	}
	// }
	for curDecl := range inspector.Root().Preorder((*ast.FuncDecl)(nil)) {
		decl := curDecl.Node().(*ast.FuncDecl)
		fn := info.Defs[decl.Name].(*types.Func)
		results := fn.Signature().Results()
		if results.Len() != 1 {
			continue // result not a singleton
		}
		retType, ok := results.At(0).Type().(*types.Named)
		if !ok {
			continue // result not a named type
		}
		switch retType.Origin().Obj() {
		case iterSeq, iterSeq2:
		default:
			continue // result not iter.Seq{,2}
		}
		// Have: a FuncDecl that returns an iterator.
		for curRet := range curDecl.Preorder((*ast.ReturnStmt)(nil)) {
			ret := curRet.Node().(*ast.ReturnStmt)
			if len(ret.Results) != 1 || !is[*ast.FuncLit](ret.Results[0]) {
				continue // not "return func(){...}"
			}
			for curRange := range curRet.Preorder((*ast.RangeStmt)(nil)) {
				rng := curRange.Node().(*ast.RangeStmt)
				call, ok := rng.X.(*ast.CallExpr)
				if !ok {
					continue
				}
				if typeutil.StaticCallee(info, call) == fn {
					pass.Report(analysis.Diagnostic{
						Pos:     rng.Range,
						End:     rng.X.End(),
						Message: fmt.Sprintf("inefficient recursion in iterator %s", fn.Name()),
					})
				}
			}
		}
	}

	return nil, nil
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}


================================================
FILE: gopls/internal/analysis/recursiveiter/recursiveiter_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package recursiveiter_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/recursiveiter"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, recursiveiter.Analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/recursiveiter/testdata/src/a/a.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package recursiveiter

import "iter"

type cons struct {
	car int
	cdr *cons
}

func (cons *cons) All() iter.Seq[int] {
	return func(yield func(int) bool) {
		// The correct recursion is:
		//   func (cons *cons) all(f func(int) bool) {
		//     return cons == nil || yield(cons.car) && cons.cdr.all()
		//   }
		// then:
		//   _ = cons.all(yield)
		if cons != nil && yield(cons.car) {
			for elem := range cons.All() { // want "inefficient recursion in iterator All"
				if !yield(elem) {
					break
				}
			}
		}
	}
}


================================================
FILE: gopls/internal/analysis/simplifycompositelit/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package simplifycompositelit defines an Analyzer that simplifies composite literals.
// https://github.com/golang/go/blob/master/src/cmd/gofmt/simplify.go
// https://golang.org/cmd/gofmt/#hdr-The_simplify_command
//
// # Analyzer simplifycompositelit
//
// simplifycompositelit: check for composite literal simplifications
//
// An array, slice, or map composite literal of the form:
//
//	[]T{T{}, T{}}
//
// will be simplified to:
//
//	[]T{{}, {}}
//
// This is one of the simplifications that "gofmt -s" applies.
//
// This analyzer ignores generated code.
package simplifycompositelit


================================================
FILE: gopls/internal/analysis/simplifycompositelit/simplifycompositelit.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package simplifycompositelit defines an Analyzer that simplifies composite literals.
// https://github.com/golang/go/blob/master/src/cmd/gofmt/simplify.go
// https://golang.org/cmd/gofmt/#hdr-The_simplify_command
package simplifycompositelit

import (
	"bytes"
	_ "embed"
	"fmt"
	"go/ast"
	"go/printer"
	"go/token"
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "simplifycompositelit",
	Doc:      analyzerutil.MustExtractDoc(doc, "simplifycompositelit"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifycompositelit",
}

func run(pass *analysis.Pass) (any, error) {
	// Gather information whether file is generated or not
	generated := make(map[*token.File]bool)
	for _, file := range pass.Files {
		if ast.IsGenerated(file) {
			generated[pass.Fset.File(file.FileStart)] = true
		}
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{(*ast.CompositeLit)(nil)}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		if _, ok := generated[pass.Fset.File(n.Pos())]; ok {
			return // skip checking if it's generated code
		}

		expr := n.(*ast.CompositeLit)

		outer := expr
		var keyType, eltType ast.Expr
		switch typ := outer.Type.(type) {
		case *ast.ArrayType:
			eltType = typ.Elt
		case *ast.MapType:
			keyType = typ.Key
			eltType = typ.Value
		}

		if eltType == nil {
			return
		}
		var ktyp reflect.Value
		if keyType != nil {
			ktyp = reflect.ValueOf(keyType)
		}
		typ := reflect.ValueOf(eltType)
		for _, x := range outer.Elts {
			// look at value of indexed/named elements
			if t, ok := x.(*ast.KeyValueExpr); ok {
				if keyType != nil {
					simplifyLiteral(pass, ktyp, keyType, t.Key)
				}
				x = t.Value
			}
			simplifyLiteral(pass, typ, eltType, x)
		}
	})
	return nil, nil
}

func simplifyLiteral(pass *analysis.Pass, typ reflect.Value, astType, x ast.Expr) {
	// if the element is a composite literal and its literal type
	// matches the outer literal's element type exactly, the inner
	// literal type may be omitted
	if inner, ok := x.(*ast.CompositeLit); ok && match(typ, reflect.ValueOf(inner.Type)) {
		var b bytes.Buffer
		printer.Fprint(&b, pass.Fset, inner.Type) // ignore error
		createDiagnostic(pass, inner.Type.Pos(), inner.Type.End(), b.String())
	}
	// if the outer literal's element type is a pointer type *T
	// and the element is & of a composite literal of type T,
	// the inner &T may be omitted.
	if ptr, ok := astType.(*ast.StarExpr); ok {
		if addr, ok := x.(*ast.UnaryExpr); ok && addr.Op == token.AND {
			if inner, ok := addr.X.(*ast.CompositeLit); ok {
				if match(reflect.ValueOf(ptr.X), reflect.ValueOf(inner.Type)) {
					var b bytes.Buffer
					printer.Fprint(&b, pass.Fset, inner.Type) // ignore error
					// Account for the & by subtracting 1 from typ.Pos().
					createDiagnostic(pass, inner.Type.Pos()-1, inner.Type.End(), "&"+b.String())
				}
			}
		}
	}
}

func createDiagnostic(pass *analysis.Pass, start, end token.Pos, typ string) {
	pass.Report(analysis.Diagnostic{
		Pos:     start,
		End:     end,
		Message: "redundant type from array, slice, or map composite literal",
		SuggestedFixes: []analysis.SuggestedFix{{
			Message: fmt.Sprintf("Remove '%s'", typ),
			TextEdits: []analysis.TextEdit{{
				Pos:     start,
				End:     end,
				NewText: []byte{},
			}},
		}},
	})
}

// match reports whether pattern matches val,
// recording wildcard submatches in m.
// If m == nil, match checks whether pattern == val.
// from https://github.com/golang/go/blob/26154f31ad6c801d8bad5ef58df1e9263c6beec7/src/cmd/gofmt/rewrite.go#L160
func match(pattern, val reflect.Value) bool {
	// Otherwise, pattern and val must match recursively.
	if !pattern.IsValid() || !val.IsValid() {
		return !pattern.IsValid() && !val.IsValid()
	}
	if pattern.Type() != val.Type() {
		return false
	}

	// Special cases.
	switch pattern.Type() {
	case identType:
		// For identifiers, only the names need to match
		// (and none of the other *ast.Object information).
		// This is a common case, handle it all here instead
		// of recursing down any further via reflection.
		p := pattern.Interface().(*ast.Ident)
		v := val.Interface().(*ast.Ident)
		return p == nil && v == nil || p != nil && v != nil && p.Name == v.Name
	case objectPtrType, positionType:
		// object pointers and token positions always match
		return true
	case callExprType:
		// For calls, the Ellipsis fields (token.Position) must
		// match since that is how f(x) and f(x...) are different.
		// Check them here but fall through for the remaining fields.
		p := pattern.Interface().(*ast.CallExpr)
		v := val.Interface().(*ast.CallExpr)
		if p.Ellipsis.IsValid() != v.Ellipsis.IsValid() {
			return false
		}
	}

	p := reflect.Indirect(pattern)
	v := reflect.Indirect(val)
	if !p.IsValid() || !v.IsValid() {
		return !p.IsValid() && !v.IsValid()
	}

	switch p.Kind() {
	case reflect.Slice:
		if p.Len() != v.Len() {
			return false
		}
		for i := 0; i < p.Len(); i++ {
			if !match(p.Index(i), v.Index(i)) {
				return false
			}
		}
		return true

	case reflect.Struct:
		for i := 0; i < p.NumField(); i++ {
			if !match(p.Field(i), v.Field(i)) {
				return false
			}
		}
		return true

	case reflect.Interface:
		return match(p.Elem(), v.Elem())
	}

	// Handle token integers, etc.
	return p.Interface() == v.Interface()
}

// Values/types for special cases.
var (
	identType     = reflect.TypeFor[*ast.Ident]()
	objectPtrType = reflect.TypeFor[*ast.Object]()
	positionType  = reflect.TypeFor[token.Pos]()
	callExprType  = reflect.TypeFor[*ast.CallExpr]()
)


================================================
FILE: gopls/internal/analysis/simplifycompositelit/simplifycompositelit_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifycompositelit_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/simplifycompositelit"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, simplifycompositelit.Analyzer, "a", "generatedcode")
}


================================================
FILE: gopls/internal/analysis/simplifycompositelit/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

type T struct {
	x, y int
}

type T2 struct {
	w, z int
}

var _ = [42]T{
	T{},     // want "redundant type from array, slice, or map composite literal"
	T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [...]T{
	T{},     // want "redundant type from array, slice, or map composite literal"
	T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []T{
	T{},     // want "redundant type from array, slice, or map composite literal"
	T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []T{
	T{}, // want "redundant type from array, slice, or map composite literal"
	10:  T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	20:  T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []struct {
	x, y int
}{
	struct{ x, y int }{}, // want "redundant type from array, slice, or map composite literal"
	10:                   struct{ x, y int }{1, 2}, // want "redundant type from array, slice, or map composite literal"
	20:                   struct{ x, y int }{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []interface{}{
	T{},
	10: T{1, 2},
	20: T{3, 4},
}

var _ = [][]int{
	[]int{},     // want "redundant type from array, slice, or map composite literal"
	[]int{1, 2}, // want "redundant type from array, slice, or map composite literal"
	[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [][]int{
	([]int{}),
	([]int{1, 2}),
	[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [][][]int{
	[][]int{}, // want "redundant type from array, slice, or map composite literal"
	[][]int{ // want "redundant type from array, slice, or map composite literal"
		[]int{},           // want "redundant type from array, slice, or map composite literal"
		[]int{0, 1, 2, 3}, // want "redundant type from array, slice, or map composite literal"
		[]int{4, 5},       // want "redundant type from array, slice, or map composite literal"
	},
}

var _ = map[string]T{
	"foo": T{},     // want "redundant type from array, slice, or map composite literal"
	"bar": T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]struct {
	x, y int
}{
	"foo": struct{ x, y int }{},     // want "redundant type from array, slice, or map composite literal"
	"bar": struct{ x, y int }{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": struct{ x, y int }{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]interface{}{
	"foo": T{},
	"bar": T{1, 2},
	"bal": T{3, 4},
}

var _ = map[string][]int{
	"foo": []int{},     // want "redundant type from array, slice, or map composite literal"
	"bar": []int{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": []int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string][]int{
	"foo": ([]int{}),
	"bar": ([]int{1, 2}),
	"bal": []int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

type Point struct {
	a int
	b int
}

type Piece struct {
	a int
	b int
	c Point
	d []Point
	e *Point
	f *Point
}

// from exp/4s/data.go
var pieces3 = []Piece{
	Piece{0, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	Piece{1, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	Piece{2, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	Piece{3, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = [42]*T{
	&T{},     // want "redundant type from array, slice, or map composite literal"
	&T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	&T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [...]*T{
	&T{},     // want "redundant type from array, slice, or map composite literal"
	&T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	&T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*T{
	&T{},     // want "redundant type from array, slice, or map composite literal"
	&T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	&T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*T{
	&T{}, // want "redundant type from array, slice, or map composite literal"
	10:   &T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	20:   &T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*struct {
	x, y int
}{
	&struct{ x, y int }{}, // want "redundant type from array, slice, or map composite literal"
	10:                    &struct{ x, y int }{1, 2}, // want "redundant type from array, slice, or map composite literal"
	20:                    &struct{ x, y int }{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []interface{}{
	&T{},
	10: &T{1, 2},
	20: &T{3, 4},
}

var _ = []*[]int{
	&[]int{},     // want "redundant type from array, slice, or map composite literal"
	&[]int{1, 2}, // want "redundant type from array, slice, or map composite literal"
	&[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*[]int{
	(&[]int{}),
	(&[]int{1, 2}),
	&[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*[]*[]int{
	&[]*[]int{}, // want "redundant type from array, slice, or map composite literal"
	&[]*[]int{ // want "redundant type from array, slice, or map composite literal"
		&[]int{},           // want "redundant type from array, slice, or map composite literal"
		&[]int{0, 1, 2, 3}, // want "redundant type from array, slice, or map composite literal"
		&[]int{4, 5},       // want "redundant type from array, slice, or map composite literal"
	},
}

var _ = map[string]*T{
	"foo": &T{},     // want "redundant type from array, slice, or map composite literal"
	"bar": &T{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": &T{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]*struct {
	x, y int
}{
	"foo": &struct{ x, y int }{},     // want "redundant type from array, slice, or map composite literal"
	"bar": &struct{ x, y int }{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": &struct{ x, y int }{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]interface{}{
	"foo": &T{},
	"bar": &T{1, 2},
	"bal": &T{3, 4},
}

var _ = map[string]*[]int{
	"foo": &[]int{},     // want "redundant type from array, slice, or map composite literal"
	"bar": &[]int{1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": &[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]*[]int{
	"foo": (&[]int{}),
	"bar": (&[]int{1, 2}),
	"bal": &[]int{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var pieces4 = []*Piece{
	&Piece{0, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	&Piece{1, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	&Piece{2, 0, Point{4, 1}, []Point{Point{0, 0}, Point{1, 0}, Point{1, 0}, Point{1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	&Piece{3, 0, Point{1, 4}, []Point{Point{0, 0}, Point{0, 1}, Point{0, 1}, Point{0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = map[T]T2{
	T{1, 2}: T2{3, 4}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	T{5, 6}: T2{7, 8}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = map[*T]*T2{
	&T{1, 2}: &T2{3, 4}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	&T{5, 6}: &T2{7, 8}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}


================================================
FILE: gopls/internal/analysis/simplifycompositelit/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

type T struct {
	x, y int
}

type T2 struct {
	w, z int
}

var _ = [42]T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [...]T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []T{
	{}, // want "redundant type from array, slice, or map composite literal"
	10: {1, 2}, // want "redundant type from array, slice, or map composite literal"
	20: {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []struct {
	x, y int
}{
	{}, // want "redundant type from array, slice, or map composite literal"
	10: {1, 2}, // want "redundant type from array, slice, or map composite literal"
	20: {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []interface{}{
	T{},
	10: T{1, 2},
	20: T{3, 4},
}

var _ = [][]int{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [][]int{
	([]int{}),
	([]int{1, 2}),
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [][][]int{
	{}, // want "redundant type from array, slice, or map composite literal"
	{ // want "redundant type from array, slice, or map composite literal"
		{},           // want "redundant type from array, slice, or map composite literal"
		{0, 1, 2, 3}, // want "redundant type from array, slice, or map composite literal"
		{4, 5},       // want "redundant type from array, slice, or map composite literal"
	},
}

var _ = map[string]T{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]struct {
	x, y int
}{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]interface{}{
	"foo": T{},
	"bar": T{1, 2},
	"bal": T{3, 4},
}

var _ = map[string][]int{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string][]int{
	"foo": ([]int{}),
	"bar": ([]int{1, 2}),
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

type Point struct {
	a int
	b int
}

type Piece struct {
	a int
	b int
	c Point
	d []Point
	e *Point
	f *Point
}

// from exp/4s/data.go
var pieces3 = []Piece{
	{0, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{1, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{2, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{3, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = [42]*T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = [...]*T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*T{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*T{
	{}, // want "redundant type from array, slice, or map composite literal"
	10: {1, 2}, // want "redundant type from array, slice, or map composite literal"
	20: {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*struct {
	x, y int
}{
	{}, // want "redundant type from array, slice, or map composite literal"
	10: {1, 2}, // want "redundant type from array, slice, or map composite literal"
	20: {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []interface{}{
	&T{},
	10: &T{1, 2},
	20: &T{3, 4},
}

var _ = []*[]int{
	{},     // want "redundant type from array, slice, or map composite literal"
	{1, 2}, // want "redundant type from array, slice, or map composite literal"
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*[]int{
	(&[]int{}),
	(&[]int{1, 2}),
	{3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = []*[]*[]int{
	{}, // want "redundant type from array, slice, or map composite literal"
	{ // want "redundant type from array, slice, or map composite literal"
		{},           // want "redundant type from array, slice, or map composite literal"
		{0, 1, 2, 3}, // want "redundant type from array, slice, or map composite literal"
		{4, 5},       // want "redundant type from array, slice, or map composite literal"
	},
}

var _ = map[string]*T{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]*struct {
	x, y int
}{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]interface{}{
	"foo": &T{},
	"bar": &T{1, 2},
	"bal": &T{3, 4},
}

var _ = map[string]*[]int{
	"foo": {},     // want "redundant type from array, slice, or map composite literal"
	"bar": {1, 2}, // want "redundant type from array, slice, or map composite literal"
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var _ = map[string]*[]int{
	"foo": (&[]int{}),
	"bar": (&[]int{1, 2}),
	"bal": {3, 4}, // want "redundant type from array, slice, or map composite literal"
}

var pieces4 = []*Piece{
	{0, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{1, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{2, 0, Point{4, 1}, []Point{{0, 0}, {1, 0}, {1, 0}, {1, 0}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{3, 0, Point{1, 4}, []Point{{0, 0}, {0, 1}, {0, 1}, {0, 1}}, nil, nil}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = map[T]T2{
	{1, 2}: {3, 4}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{5, 6}: {7, 8}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}

var _ = map[*T]*T2{
	{1, 2}: {3, 4}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
	{5, 6}: {7, 8}, // want "redundant type from array, slice, or map composite literal" "redundant type from array, slice, or map composite literal"
}


================================================
FILE: gopls/internal/analysis/simplifycompositelit/testdata/src/generatedcode/generatedcode.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

type T struct {
	x, y int
}

var _ = [42]T{
	T{}, // No simplification fix is offered in generated code.
	T{1, 2}, // No simplification fix is offered in generated code.
	T{3, 4}, // No simplification fix is offered in generated code.
}


================================================
FILE: gopls/internal/analysis/simplifycompositelit/testdata/src/generatedcode/generatedcode.go.golden
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

type T struct {
	x, y int
}

var _ = [42]T{
	T{}, // No simplification fix is offered in generated code.
	T{1, 2}, // No simplification fix is offered in generated code.
	T{3, 4}, // No simplification fix is offered in generated code.
}


================================================
FILE: gopls/internal/analysis/simplifyrange/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package simplifyrange defines an Analyzer that simplifies range statements.
// https://golang.org/cmd/gofmt/#hdr-The_simplify_command
// https://github.com/golang/go/blob/master/src/cmd/gofmt/simplify.go
//
// # Analyzer simplifyrange
//
// simplifyrange: check for range statement simplifications
//
// A range of the form:
//
//	for x, _ = range v {...}
//
// will be simplified to:
//
//	for x = range v {...}
//
// A range of the form:
//
//	for _ = range v {...}
//
// will be simplified to:
//
//	for range v {...}
//
// This is one of the simplifications that "gofmt -s" applies.
//
// This analyzer ignores generated code.
package simplifyrange


================================================
FILE: gopls/internal/analysis/simplifyrange/simplifyrange.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifyrange

import (
	_ "embed"
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "simplifyrange",
	Doc:      analyzerutil.MustExtractDoc(doc, "simplifyrange"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyrange",
}

func run(pass *analysis.Pass) (any, error) {
	// Gather information whether file is generated or not
	generated := make(map[*token.File]bool)
	for _, file := range pass.Files {
		if ast.IsGenerated(file) {
			generated[pass.Fset.File(file.FileStart)] = true
		}
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.RangeStmt)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		rng := n.(*ast.RangeStmt)

		kblank := isBlank(rng.Key)
		vblank := isBlank(rng.Value)
		var start, end token.Pos
		switch {
		case kblank && (rng.Value == nil || vblank):
			// for _    = range x {}
			// for _, _ = range x {}
			//     ^^^^^^^
			start, end = rng.Key.Pos(), rng.Range

		case vblank:
			// for k, _ := range x {}
			//      ^^^
			start, end = rng.Key.End(), rng.Value.End()

		default:
			return
		}

		if generated[pass.Fset.File(n.Pos())] {
			return
		}

		pass.Report(analysis.Diagnostic{
			Pos:     start,
			End:     end,
			Message: "simplify range expression",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Remove empty value",
				TextEdits: []analysis.TextEdit{{
					Pos: start,
					End: end,
				}},
			}},
		})
	})
	return nil, nil
}

func isBlank(e ast.Expr) bool {
	id, ok := e.(*ast.Ident)
	return ok && id.Name == "_"
}


================================================
FILE: gopls/internal/analysis/simplifyrange/simplifyrange_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifyrange_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/simplifyrange"
)

func Test(t *testing.T) {
	analysistest.RunWithSuggestedFixes(t, analysistest.TestData(), simplifyrange.Analyzer,
		"a",
		"generatedcode",
		"rangeoverfunc")
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

import "log"

func m() {
	maps := make(map[string]string)
	for k, _ := range maps { // want "simplify range expression"
		log.Println(k)
	}
	for _ = range maps { // want "simplify range expression"
	}
	for _, _ = range maps { // want "simplify range expression"
	}
	for _, v := range maps { // nope
		println(v)
	}
	for range maps { // nope
	}
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

import "log"

func m() {
	maps := make(map[string]string)
	for k := range maps { // want "simplify range expression"
		log.Println(k)
	}
	for range maps { // want "simplify range expression"
	}
	for range maps { // want "simplify range expression"
	}
	for _, v := range maps { // nope
		println(v)
	}
	for range maps { // nope
	}
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/generatedcode/generatedcode.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

import "log"

func mgeneratedcode() {
	maps := make(map[string]string)
	for k, _ := range maps { // No simplification fix is offered in generated code.
		log.Println(k)
	}
	for _ = range maps { // No simplification fix is offered in generated code.
	}
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/generatedcode/generatedcode.go.golden
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

import "log"

func mgeneratedcode() {
	maps := make(map[string]string)
	for k, _ := range maps { // No simplification fix is offered in generated code.
		log.Println(k)
	}
	for _ = range maps { // No simplification fix is offered in generated code.
	}
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/rangeoverfunc/rangeoverfunc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

import "iter"

func _(seq1 iter.Seq[int], seq2 iter.Seq2[int, int]) {
	// range-over-func is (once again) consistent with other types (#65236)
	for _ = range "" { // want "simplify range expression"
	}
	for _ = range seq1 { // want `simplify range expression`
	}
	for _, v := range seq2 { // silence
		_ = v
	}
	for _, _ = range seq2 { // want `simplify range expression`
	}
}


================================================
FILE: gopls/internal/analysis/simplifyrange/testdata/src/rangeoverfunc/rangeoverfunc.go.golden
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

import "iter"

func _(seq1 iter.Seq[int], seq2 iter.Seq2[int, int]) {
	// range-over-func is (once again) consistent with other types (#65236)
	for range "" { // want "simplify range expression"
	}
	for range seq1 { // want `simplify range expression`
	}
	for _, v := range seq2 { // silence
		_ = v
	}
	for range seq2 { // want `simplify range expression`
	}
}


================================================
FILE: gopls/internal/analysis/simplifyslice/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package simplifyslice defines an Analyzer that simplifies slice statements.
// https://github.com/golang/go/blob/master/src/cmd/gofmt/simplify.go
// https://golang.org/cmd/gofmt/#hdr-The_simplify_command
//
// # Analyzer simplifyslice
//
// simplifyslice: check for slice simplifications
//
// A slice expression of the form:
//
//	s[a:len(s)]
//
// will be simplified to:
//
//	s[a:]
//
// This is one of the simplifications that "gofmt -s" applies.
//
// This analyzer ignores generated code.
package simplifyslice


================================================
FILE: gopls/internal/analysis/simplifyslice/simplifyslice.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifyslice

import (
	"bytes"
	_ "embed"
	"fmt"
	"go/ast"
	"go/printer"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "simplifyslice",
	Doc:      analyzerutil.MustExtractDoc(doc, "simplifyslice"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyslice",
}

// Note: We could also simplify slice expressions of the form s[0:b] to s[:b]
//       but we leave them as is since sometimes we want to be very explicit
//       about the lower bound.
// An example where the 0 helps:
//       x, y, z := b[0:2], b[2:4], b[4:6]
// An example where it does not:
//       x, y := b[:n], b[n:]

func run(pass *analysis.Pass) (any, error) {
	// Gather information whether file is generated or not
	generated := make(map[*token.File]bool)
	for _, file := range pass.Files {
		if ast.IsGenerated(file) {
			generated[pass.Fset.File(file.FileStart)] = true
		}
	}

	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
	nodeFilter := []ast.Node{
		(*ast.SliceExpr)(nil),
	}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		if _, ok := generated[pass.Fset.File(n.Pos())]; ok {
			return // skip checking if it's generated code
		}

		expr := n.(*ast.SliceExpr)
		// - 3-index slices always require the 2nd and 3rd index
		if expr.Max != nil {
			return
		}
		s, ok := expr.X.(*ast.Ident)
		// the array/slice object is a single, resolved identifier
		if !ok || s.Obj == nil {
			return
		}
		call, ok := expr.High.(*ast.CallExpr)
		// the high expression is a function call with a single argument
		if !ok || len(call.Args) != 1 || call.Ellipsis.IsValid() {
			return
		}
		fun, ok := call.Fun.(*ast.Ident)
		// the function called is "len" and it is not locally defined; and
		// because we don't have dot imports, it must be the predefined len()
		if !ok || fun.Name != "len" || fun.Obj != nil {
			return
		}
		arg, ok := call.Args[0].(*ast.Ident)
		// the len argument is the array/slice object
		if !ok || arg.Obj != s.Obj {
			return
		}
		var b bytes.Buffer
		printer.Fprint(&b, pass.Fset, expr.High) // ignore error
		pass.Report(analysis.Diagnostic{
			Pos:     expr.High.Pos(),
			End:     expr.High.End(),
			Message: fmt.Sprintf("unneeded: %s", b.String()),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: fmt.Sprintf("Remove '%s'", b.String()),
				TextEdits: []analysis.TextEdit{{
					Pos:     expr.High.Pos(),
					End:     expr.High.End(),
					NewText: []byte{},
				}},
			}},
		})
	})
	return nil, nil
}


================================================
FILE: gopls/internal/analysis/simplifyslice/simplifyslice_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package simplifyslice_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/simplifyslice"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, simplifyslice.Analyzer, "a", "generatedcode", "typeparams")
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/a/a.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

var (
	a [10]byte
	b [20]float32
	s []int
	t struct {
		s []byte
	}

	_ = a[0:]
	_ = a[1:10]
	_ = a[2:len(a)] // want "unneeded: len\\(a\\)"
	_ = a[3:(len(a))]
	_ = a[len(a)-1 : len(a)] // want "unneeded: len\\(a\\)"
	_ = a[2:len(a):len(a)]

	_ = a[:]
	_ = a[:10]
	_ = a[:len(a)] // want "unneeded: len\\(a\\)"
	_ = a[:(len(a))]
	_ = a[:len(a)-1]
	_ = a[:len(a):len(a)]

	_ = s[0:]
	_ = s[1:10]
	_ = s[2:len(s)] // want "unneeded: len\\(s\\)"
	_ = s[3:(len(s))]
	_ = s[len(a) : len(s)-1]
	_ = s[0:len(b)]
	_ = s[2:len(s):len(s)]

	_ = s[:]
	_ = s[:10]
	_ = s[:len(s)] // want "unneeded: len\\(s\\)"
	_ = s[:(len(s))]
	_ = s[:len(s)-1]
	_ = s[:len(b)]
	_ = s[:len(s):len(s)]

	_ = t.s[0:]
	_ = t.s[1:10]
	_ = t.s[2:len(t.s)]
	_ = t.s[3:(len(t.s))]
	_ = t.s[len(a) : len(t.s)-1]
	_ = t.s[0:len(b)]
	_ = t.s[2:len(t.s):len(t.s)]

	_ = t.s[:]
	_ = t.s[:10]
	_ = t.s[:len(t.s)]
	_ = t.s[:(len(t.s))]
	_ = t.s[:len(t.s)-1]
	_ = t.s[:len(b)]
	_ = t.s[:len(t.s):len(t.s)]
)

func _() {
	s := s[0:len(s)] // want "unneeded: len\\(s\\)"
	_ = s
}

func m() {
	maps := []int{}
	_ = maps[1:len(maps)] // want "unneeded: len\\(maps\\)"
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/a/a.go.golden
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

var (
	a [10]byte
	b [20]float32
	s []int
	t struct {
		s []byte
	}

	_ = a[0:]
	_ = a[1:10]
	_ = a[2:] // want "unneeded: len\\(a\\)"
	_ = a[3:(len(a))]
	_ = a[len(a)-1:] // want "unneeded: len\\(a\\)"
	_ = a[2:len(a):len(a)]

	_ = a[:]
	_ = a[:10]
	_ = a[:] // want "unneeded: len\\(a\\)"
	_ = a[:(len(a))]
	_ = a[:len(a)-1]
	_ = a[:len(a):len(a)]

	_ = s[0:]
	_ = s[1:10]
	_ = s[2:] // want "unneeded: len\\(s\\)"
	_ = s[3:(len(s))]
	_ = s[len(a) : len(s)-1]
	_ = s[0:len(b)]
	_ = s[2:len(s):len(s)]

	_ = s[:]
	_ = s[:10]
	_ = s[:] // want "unneeded: len\\(s\\)"
	_ = s[:(len(s))]
	_ = s[:len(s)-1]
	_ = s[:len(b)]
	_ = s[:len(s):len(s)]

	_ = t.s[0:]
	_ = t.s[1:10]
	_ = t.s[2:len(t.s)]
	_ = t.s[3:(len(t.s))]
	_ = t.s[len(a) : len(t.s)-1]
	_ = t.s[0:len(b)]
	_ = t.s[2:len(t.s):len(t.s)]

	_ = t.s[:]
	_ = t.s[:10]
	_ = t.s[:len(t.s)]
	_ = t.s[:(len(t.s))]
	_ = t.s[:len(t.s)-1]
	_ = t.s[:len(b)]
	_ = t.s[:len(t.s):len(t.s)]
)

func _() {
	s := s[0:] // want "unneeded: len\\(s\\)"
	_ = s
}

func m() {
	maps := []int{}
	_ = maps[1:] // want "unneeded: len\\(maps\\)"
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/generatedcode/generatedcode.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

var (
	a [10]byte
	b [20]float32
	s []int
	t struct {
		s []byte
	}

	_ = a[0:]
	_ = a[1:10]
	_ = a[2:len(a)] // No simplification fix is offered in generated code.
	_ = a[3:(len(a))]
	_ = a[len(a)-1 : len(a)] // No simplification fix is offered in generated code.
	_ = a[2:len(a):len(a)]

	_ = a[:]
	_ = a[:10]
	_ = a[:len(a)] // No simplification fix is offered in generated code.
	_ = a[:(len(a))]
	_ = a[:len(a)-1]
	_ = a[:len(a):len(a)]

	_ = s[0:]
	_ = s[1:10]
	_ = s[2:len(s)] // No simplification fix is offered in generated code.
	_ = s[3:(len(s))]
	_ = s[len(a) : len(s)-1]
	_ = s[0:len(b)]
	_ = s[2:len(s):len(s)]

	_ = s[:]
	_ = s[:10]
	_ = s[:len(s)] // No simplification fix is offered in generated code.
	_ = s[:(len(s))]
	_ = s[:len(s)-1]
	_ = s[:len(b)]
	_ = s[:len(s):len(s)]

	_ = t.s[0:]
	_ = t.s[1:10]
	_ = t.s[2:len(t.s)]
	_ = t.s[3:(len(t.s))]
	_ = t.s[len(a) : len(t.s)-1]
	_ = t.s[0:len(b)]
	_ = t.s[2:len(t.s):len(t.s)]

	_ = t.s[:]
	_ = t.s[:10]
	_ = t.s[:len(t.s)]
	_ = t.s[:(len(t.s))]
	_ = t.s[:len(t.s)-1]
	_ = t.s[:len(b)]
	_ = t.s[:len(t.s):len(t.s)]
)

func _() {
	s := s[0:len(s)] // No simplification fix is offered in generated code.
	_ = s
}

func m() {
	maps := []int{}
	_ = maps[1:len(maps)] // No simplification fix is offered in generated code.
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/generatedcode/generatedcode.go.golden
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated with somegen DO NOT EDIT.

package testdata

var (
	a [10]byte
	b [20]float32
	s []int
	t struct {
		s []byte
	}

	_ = a[0:]
	_ = a[1:10]
	_ = a[2:len(a)] // No simplification fix is offered in generated code.
	_ = a[3:(len(a))]
	_ = a[len(a)-1 : len(a)] // No simplification fix is offered in generated code.
	_ = a[2:len(a):len(a)]

	_ = a[:]
	_ = a[:10]
	_ = a[:len(a)] // No simplification fix is offered in generated code.
	_ = a[:(len(a))]
	_ = a[:len(a)-1]
	_ = a[:len(a):len(a)]

	_ = s[0:]
	_ = s[1:10]
	_ = s[2:len(s)] // No simplification fix is offered in generated code.
	_ = s[3:(len(s))]
	_ = s[len(a) : len(s)-1]
	_ = s[0:len(b)]
	_ = s[2:len(s):len(s)]

	_ = s[:]
	_ = s[:10]
	_ = s[:len(s)] // No simplification fix is offered in generated code.
	_ = s[:(len(s))]
	_ = s[:len(s)-1]
	_ = s[:len(b)]
	_ = s[:len(s):len(s)]

	_ = t.s[0:]
	_ = t.s[1:10]
	_ = t.s[2:len(t.s)]
	_ = t.s[3:(len(t.s))]
	_ = t.s[len(a) : len(t.s)-1]
	_ = t.s[0:len(b)]
	_ = t.s[2:len(t.s):len(t.s)]

	_ = t.s[:]
	_ = t.s[:10]
	_ = t.s[:len(t.s)]
	_ = t.s[:(len(t.s))]
	_ = t.s[:len(t.s)-1]
	_ = t.s[:len(b)]
	_ = t.s[:len(t.s):len(t.s)]
)

func _() {
	s := s[0:len(s)] // No simplification fix is offered in generated code.
	_ = s
}

func m() {
	maps := []int{}
	_ = maps[1:len(maps)] // No simplification fix is offered in generated code.
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

type List[E any] []E

// TODO(suzmue): add a test for generic slice expressions when https://github.com/golang/go/issues/48618 is closed.
// type S interface{ ~[]int }

var (
	a [10]byte
	b [20]float32
	p List[int]

	_ = p[0:]
	_ = p[1:10]
	_ = p[2:len(p)] // want "unneeded: len\\(p\\)"
	_ = p[3:(len(p))]
	_ = p[len(a) : len(p)-1]
	_ = p[0:len(b)]
	_ = p[2:len(p):len(p)]

	_ = p[:]
	_ = p[:10]
	_ = p[:len(p)] // want "unneeded: len\\(p\\)"
	_ = p[:(len(p))]
	_ = p[:len(p)-1]
	_ = p[:len(b)]
	_ = p[:len(p):len(p)]
)

func foo[E any](a List[E]) {
	_ = a[0:len(a)] // want "unneeded: len\\(a\\)"
}


================================================
FILE: gopls/internal/analysis/simplifyslice/testdata/src/typeparams/typeparams.go.golden
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testdata

type List[E any] []E

// TODO(suzmue): add a test for generic slice expressions when https://github.com/golang/go/issues/48618 is closed.
// type S interface{ ~[]int }

var (
	a [10]byte
	b [20]float32
	p List[int]

	_ = p[0:]
	_ = p[1:10]
	_ = p[2:] // want "unneeded: len\\(p\\)"
	_ = p[3:(len(p))]
	_ = p[len(a) : len(p)-1]
	_ = p[0:len(b)]
	_ = p[2:len(p):len(p)]

	_ = p[:]
	_ = p[:10]
	_ = p[:] // want "unneeded: len\\(p\\)"
	_ = p[:(len(p))]
	_ = p[:len(p)-1]
	_ = p[:len(b)]
	_ = p[:len(p):len(p)]
)

func foo[E any](a List[E]) {
	_ = a[0:] // want "unneeded: len\\(a\\)"
}


================================================
FILE: gopls/internal/analysis/unusedfunc/doc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedfunc defines an analyzer that checks for unused
// functions and methods
//
// # Analyzer unusedfunc
//
// unusedfunc: check for unused functions, methods, etc
//
// The unusedfunc analyzer reports functions and methods that are
// never referenced outside of their own declaration.
//
// A function is considered unused if it is unexported and not
// referenced (except within its own declaration).
//
// A method is considered unused if it is unexported, not referenced
// (except within its own declaration), and its name does not match
// that of any method of an interface type declared within the same
// package.
//
// The tool may report false positives in some situations, for
// example:
//
//   - for a declaration of an unexported function that is referenced
//     from another package using the go:linkname mechanism, if the
//     declaration's doc comment does not also have a go:linkname
//     comment.
//
//     (Such code is in any case strongly discouraged: linkname
//     annotations, if they must be used at all, should be used on both
//     the declaration and the alias.)
//
//   - for compiler intrinsics in the "runtime" package that, though
//     never referenced, are known to the compiler and are called
//     indirectly by compiled object code.
//
//   - for functions called only from assembly.
//
//   - for functions called only from files whose build tags are not
//     selected in the current build configuration.
//
// Since these situations are relatively common in the low-level parts
// of the runtime, this analyzer ignores the standard library.
// See https://go.dev/issue/71686 and https://go.dev/issue/74130 for
// further discussion of these limitations.
//
// The unusedfunc algorithm is not as precise as the
// golang.org/x/tools/cmd/deadcode tool, but it has the advantage that
// it runs within the modular analysis framework, enabling near
// real-time feedback within gopls.
//
// The unusedfunc analyzer also reports unused types, vars, and
// constants. Enums--constants defined with iota--are ignored since
// even the unused values must remain present to preserve the logical
// ordering.
package unusedfunc


================================================
FILE: gopls/internal/analysis/unusedfunc/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The unusedfunc command runs the unusedfunc analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/unusedfunc"
)

func main() { singlechecker.Main(unusedfunc.Analyzer) }


================================================
FILE: gopls/internal/analysis/unusedfunc/testdata/basic.txtar
================================================
Basic test of unusedfunc.

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

func main() {
	_ = live
}

// -- functions --

func Exported() {}

func dead() { // want `function "dead" is unused`
}

func deadRecursive() int { // want `function "deadRecursive" is unused`
	return deadRecursive()
}

func live() {}

//go:linkname foo
func apparentlyDeadButHasPrecedingLinknameComment() {}

// -- methods --

type ExportedType int
type unexportedType int

func (ExportedType) Exported()   {}
func (unexportedType) Exported() {}

func (x ExportedType) dead() { // want `method "dead" is unused`
	x.dead()
}

func (u unexportedType) dead() { // want `method "dead" is unused`
	u.dead()
}

func (x ExportedType) dynamic() {} // matches name of interface method => live

type _ interface{ dynamic() }

// -- types without methods --

type ExportedType2 int

// self-references don't count
type unusedUnexportedType2 struct{ *unusedUnexportedType2 } // want `type "unusedUnexportedType2" is unused`

type (
	one int
	two one // want `type "two" is unused`
)

// -- generic methods --

type g[T any] int

func (g[T]) method() {} // want `method "method" is unused`

// -- constants --

const unusedConst = 1 // want `const "unusedConst" is unused`

const (
	unusedEnum = iota // want `const "unusedEnum" is unused`
)

const constOne = 1
const unusedConstTwo = constOne // want `const "unusedConstTwo" is unused`
const _, unusedConstThree = 0, 3 // want `const "unusedConstThree" is unused`
const unusedConstFour, _ = 4, 0 // want `const "unusedConstFour" is unused`
const unusedConstFive, UsedConst6 = 4, 6 // want `const "unusedConstFive" is unused`

// This test verifies the fix for golang/go#76924.
// We no longer produce unused variable warnings for a group
// of unused constants if all constants have the same type and
// at least one is used.

const (
	a = "a"
	b = "b"
	c = "c"
)

func _() {
	print(a)
}

const ( // want `all values in this set of constants are unused`
	d = "d"
	e = "e"
)

// -- vars --

var unusedVar = 1 // want `var "unusedVar" is unused`

var (
	unusedVar2 = 1 // want `var "unusedVar2" is unused`
)

var (
	usedVar int
	unusedVar3 = usedVar // want `var "unusedVar3" is unused`
	_, unusedVar4, _ = Triple() // want `var "unusedVar4" is unused`
)

func Triple() (int, int, int)

-- a/a.go.golden --
package a

func main() {
	_ = live
}

// -- functions --

func Exported() {}

func live() {}

//go:linkname foo
func apparentlyDeadButHasPrecedingLinknameComment() {}

// -- methods --

type ExportedType int
type unexportedType int

func (ExportedType) Exported()   {}
func (unexportedType) Exported() {}

func (x ExportedType) dynamic() {} // matches name of interface method => live

type _ interface{ dynamic() }


// -- types without methods --

type ExportedType2 int

type (
	one int
)

// -- generic methods --

type g[T any] int

// -- constants --

const constOne = 1

const UsedConst6 = 6 // want `const "unusedConstFive" is unused`

// This test verifies the fix for golang/go#76924.
// We no longer produce unused variable warnings for a group
// of unused constants if all constants have the same type and
// at least one is used.

const (
	a = "a"
	b = "b"
	c = "c"
)

func _() {
	print(a)
}

// -- vars --

var (
	usedVar int
	_, _, _ = Triple() // want `var "unusedVar4" is unused`
)

func Triple() (int, int, int)


================================================
FILE: gopls/internal/analysis/unusedfunc/unusedfunc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedfunc

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	typeindexanalyzer "golang.org/x/tools/internal/analysis/typeindex"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

// Assumptions
//
// Like unusedparams, this analyzer depends on the invariant of the
// gopls analysis driver that only the "widest" package (the one with
// the most files) for a given file is analyzed. This invariant allows
// the algorithm to make "closed world" assumptions about the target
// package. (In general, analysis of Go test packages cannot make that
// assumption because in-package tests add new files to existing
// packages, potentially invalidating results.) Consequently, running
// this analyzer in, say, unitchecker or multichecker may produce
// incorrect results.
//
// A function is unreferenced if it is never referenced except within
// its own declaration, and it is unexported. (Exported functions must
// be assumed to be referenced from other packages.)
//
// For methods, we assume that the receiver type is "live" (variables
// of that type are created) and "address taken" (its rtype ends up in
// an at least one interface value). This means exported methods may
// be called via reflection or by interfaces defined in other
// packages, so again we are concerned only with unexported methods.
//
// To discount the possibility of a method being called via an
// interface, we must additionally ensure that no literal interface
// type within the package has a method of the same name.
// (Unexported methods cannot be called through interfaces declared
// in other packages because each package has a private namespace
// for unexported identifiers.)
//
// Types (sans methods), constants, and vars are more straightforward.
//
// For enums (defined here as const decls where all consts have the same type),
// we only require that one of the names in the group is used, since it is
// common for at least some values to be unused when they are added for
// symmetry, future use, or to conform to some external pattern.

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "unusedfunc",
	Doc:      analyzerutil.MustExtractDoc(doc, "unusedfunc"),
	Requires: []*analysis.Analyzer{inspect.Analyzer, typeindexanalyzer.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedfunc",
}

func run(pass *analysis.Pass) (any, error) {
	// The standard library makes heavy use of intrinsics, linknames, etc,
	// that confuse this algorithm; so skip it (#74130).
	if packagepath.IsStdPackage(pass.Pkg.Path()) {
		return nil, nil
	}

	var (
		inspect = pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		index   = pass.ResultOf[typeindexanalyzer.Analyzer].(*typeindex.Index)
	)

	// Gather names of unexported interface methods declared in this package.
	localIfaceMethods := make(map[string]bool)
	nodeFilter := []ast.Node{(*ast.InterfaceType)(nil)}
	inspect.Preorder(nodeFilter, func(n ast.Node) {
		iface := n.(*ast.InterfaceType)
		for _, field := range iface.Methods.List {
			if len(field.Names) > 0 {
				id := field.Names[0]
				if !id.IsExported() {
					// TODO(adonovan): check not just name but signature too.
					localIfaceMethods[id.Name] = true
				}
			}
		}
	})

	// used reports whether the object declared at id is (potentially) used.
	// References within curSelf are ignored.
	used := func(id *ast.Ident, curSelf inspector.Cursor) bool {
		// Exported functions may be called from other packages.
		if id.IsExported() {
			return true
		}

		// Blank functions are exempt from diagnostics.
		if id.Name == "_" {
			return true
		}

		// Check for uses (including selections).
		obj := pass.TypesInfo.Defs[id]
		for curId := range index.Uses(obj) {
			// Ignore self references.
			if !curSelf.Contains(curId) {
				return true // symbol is referenced
			}
		}
		return false
	}

	// checkUnused reports a diagnostic if the object declared at id
	// is unexported and unused. References within curSelf are ignored.
	checkUnused := func(noun string, id *ast.Ident, curSelf inspector.Cursor, delete func() []analysis.TextEdit) {
		if used(id, curSelf) {
			return
		}

		pass.Report(analysis.Diagnostic{
			Pos:     id.Pos(),
			End:     id.End(),
			Message: fmt.Sprintf("%s %q is unused", noun, id.Name),
			SuggestedFixes: []analysis.SuggestedFix{{
				Message:   fmt.Sprintf("Delete %s %q", noun, id.Name),
				TextEdits: delete(),
			}},
		})
	}

	// isEnum returns true if the decl curGenDecl is a const decl with more than one
	// spec where all consts are the same type.
	isEnum := func(curGenDecl inspector.Cursor) bool {
		decl := curGenDecl.Node().(*ast.GenDecl)
		if decl.Tok != token.CONST || len(decl.Specs) < 2 {
			return false
		}
		var prevType types.Type
		for _, spec := range decl.Specs {
			spec := spec.(*ast.ValueSpec)
			for _, id := range spec.Names {
				curType := pass.TypesInfo.TypeOf(id)
				if prevType != nil && !types.Identical(curType, prevType) {
					return false
				}
				prevType = curType
			}
		}
		return true
	}

	// Check each package-level declaration (and method) for uses.
	for curFile := range inspect.Root().Preorder((*ast.File)(nil)) {
		file := curFile.Node().(*ast.File)
		if ast.IsGenerated(file) {
			continue // skip generated files
		}
		tokFile := pass.Fset.File(file.Pos())

	nextDecl:
		for i := range file.Decls {
			curDecl := curFile.ChildAt(edge.File_Decls, i)
			decl := curDecl.Node().(ast.Decl)

			// Skip if there's a preceding //go:linkname directive.
			// (This is relevant only to func and var decls.)
			//
			// (A program can link fine without such a directive,
			// but it is bad style; and the directive may
			// appear anywhere, not just on the preceding line,
			// but again that is poor form.)
			if doc := astutil.DocComment(decl); doc != nil {
				for _, comment := range doc.List {
					// TODO(adonovan): use ast.ParseDirective when #68021 lands.
					if strings.HasPrefix(comment.Text, "//go:linkname ") {
						continue nextDecl
					}
				}
			}

			switch decl := decl.(type) {
			case *ast.FuncDecl:
				id := decl.Name
				// An (unexported) method whose name matches an
				// interface method declared in the same package
				// may be dynamically called via that interface.
				if decl.Recv != nil && localIfaceMethods[id.Name] {
					continue
				}

				// main and init functions are implicitly always used
				if decl.Recv == nil && (id.Name == "init" || id.Name == "main") {
					continue
				}

				noun := cond(decl.Recv == nil, "function", "method")
				checkUnused(noun, decl.Name, curDecl, func() []analysis.TextEdit {
					return refactor.DeleteDecl(tokFile, curDecl)
				})

			case *ast.GenDecl:
				switch decl.Tok {
				case token.TYPE:
					for i, spec := range decl.Specs {
						var (
							spec    = spec.(*ast.TypeSpec)
							id      = spec.Name
							curSpec = curDecl.ChildAt(edge.GenDecl_Specs, i)
						)
						checkUnused("type", id, curSpec, func() []analysis.TextEdit {
							return refactor.DeleteSpec(tokFile, curSpec)
						})
					}

				case token.CONST, token.VAR:
					if isEnum(curDecl) {
						// For enum-like constants, a use of any
						// name acts as a use of the whole.
						// TODO(mkalil): This results in false negatives, for example:
						// const (
						//	 a = 0
						//	 b = a + 1
						// )
						// We report that a is "used" even though is not used outside the const
						// decl, and since we do not report errors in enums that have at least one
						// used name, we do not report a diagnostic at all.
						allUnused := true
						for i, spec := range decl.Specs {
							curSpec := curDecl.ChildAt(edge.GenDecl_Specs, i)
							for _, id := range spec.(*ast.ValueSpec).Names {
								if used(id, curSpec) {
									allUnused = false
									break
								}
							}
						}
						if allUnused {
							edits := refactor.DeleteDecl(tokFile, curDecl)
							pass.Report(analysis.Diagnostic{
								Pos:     decl.Pos(),
								End:     decl.End(),
								Message: "all values in this set of constants are unused",
								SuggestedFixes: []analysis.SuggestedFix{{
									Message:   "Delete the constants declaration",
									TextEdits: edits,
								}},
							})
						}
					} else {
						for i, spec := range decl.Specs {
							spec := spec.(*ast.ValueSpec)
							curSpec := curDecl.ChildAt(edge.GenDecl_Specs, i)

							for j, id := range spec.Names {
								checkUnused(decl.Tok.String(), id, curSpec, func() []analysis.TextEdit {
									curId := curSpec.ChildAt(edge.ValueSpec_Names, j)
									return refactor.DeleteVar(tokFile, pass.TypesInfo, curId)
								})
							}
						}
					}
				}
			}
		}
	}

	return nil, nil
}

func cond[T any](cond bool, t, f T) T {
	if cond {
		return t
	} else {
		return f
	}
}


================================================
FILE: gopls/internal/analysis/unusedfunc/unusedfunc_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedfunc_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/unusedfunc"
	"golang.org/x/tools/internal/testfiles"
)

func Test(t *testing.T) {
	dir := testfiles.ExtractTxtarFileToTmp(t, filepath.Join(analysistest.TestData(), "basic.txtar"))
	analysistest.RunWithSuggestedFixes(t, dir, unusedfunc.Analyzer, "example.com/a")
}


================================================
FILE: gopls/internal/analysis/unusedparams/cmd/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The unusedparams command runs the unusedparams analyzer.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/unusedparams"
)

func main() { singlechecker.Main(unusedparams.Analyzer) }


================================================
FILE: gopls/internal/analysis/unusedparams/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedparams defines an analyzer that checks for unused
// parameters of functions.
//
// # Analyzer unusedparams
//
// unusedparams: check for unused parameters of functions
//
// The unusedparams analyzer checks functions to see if there are
// any parameters that are not being used.
//
// To ensure soundness, it ignores:
//   - "address-taken" functions, that is, functions that are used as
//     a value rather than being called directly; their signatures may
//     be required to conform to a func type.
//   - exported functions or methods, since they may be address-taken
//     in another package.
//   - unexported methods whose name matches an interface method
//     declared in the same package, since the method's signature
//     may be required to conform to the interface type.
//   - functions with empty bodies, or containing just a call to panic.
//   - parameters that are unnamed, or named "_", the blank identifier.
//
// The analyzer suggests a fix of replacing the parameter name by "_",
// but in such cases a deeper fix can be obtained by invoking the
// "Refactor: remove unused parameter" code action, which will
// eliminate the parameter entirely, along with all corresponding
// arguments at call sites, while taking care to preserve any side
// effects in the argument expressions; see
// https://github.com/golang/tools/releases/tag/gopls%2Fv0.14.
//
// This analyzer ignores generated code.
package unusedparams


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/a/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"bytes"
	"fmt"
	"net/http"
)

type parent interface {
	n(f bool)
}

type yuh struct {
	a int
}

func (y *yuh) n(f bool) {
	for i := 0; i < 10; i++ {
		fmt.Println(i)
	}
}

func a(i1 int, i2 int, i3 int) int { // want "unused parameter: i2"
	i3 += i1
	_ = func(z int) int { // want "unused parameter: z"
		_ = 1
		return 1
	}
	return i3
}

func b(c bytes.Buffer) { // want "unused parameter: c"
	_ = 1
}

func z(h http.ResponseWriter, _ *http.Request) { // no report: func z is address-taken
	fmt.Println("Before")
}

func l(h http.Handler) http.Handler { // want "unused parameter: h"
	return http.HandlerFunc(z)
}

func mult(a, b int) int { // want "unused parameter: b"
	a += 1
	return a
}

func y(a int) {
	panic("yo")
}

var _ = func(x int) {} // empty body: no diagnostic

var _ = func(x int) { println() } // want "unused parameter: x"

var (
	calledGlobal       = func(x int) { println() } // want "unused parameter: x"
	addressTakenGlobal = func(x int) { println() } // no report: function is address-taken
)

func _() {
	calledGlobal(1)
	println(addressTakenGlobal)
}

func Exported(unused int) {} // no finding: an exported function may be address-taken

type T int

func (T) m(f bool) { println() } // want "unused parameter: f"
func (T) n(f bool) { println() } // no finding: n may match the interface method parent.n

func _() {
	var fib func(x, y int) int
	fib = func(x, y int) int { // want "unused parameter: y"
		if x < 2 {
			return x
		}
		return fib(x-1, 123) + fib(x-2, 456)
	}
	fib(10, 42)
}


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/a/a.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"bytes"
	"fmt"
	"net/http"
)

type parent interface {
	n(f bool)
}

type yuh struct {
	a int
}

func (y *yuh) n(f bool) {
	for i := 0; i < 10; i++ {
		fmt.Println(i)
	}
}

func a(i1 int, _ int, i3 int) int { // want "unused parameter: i2"
	i3 += i1
	_ = func(_ int) int { // want "unused parameter: z"
		_ = 1
		return 1
	}
	return i3
}

func b(_ bytes.Buffer) { // want "unused parameter: c"
	_ = 1
}

func z(h http.ResponseWriter, _ *http.Request) { // no report: func z is address-taken
	fmt.Println("Before")
}

func l(_ http.Handler) http.Handler { // want "unused parameter: h"
	return http.HandlerFunc(z)
}

func mult(a, _ int) int { // want "unused parameter: b"
	a += 1
	return a
}

func y(a int) {
	panic("yo")
}

var _ = func(x int) {} // empty body: no diagnostic

var _ = func(_ int) { println() } // want "unused parameter: x"

var (
	calledGlobal       = func(_ int) { println() } // want "unused parameter: x"
	addressTakenGlobal = func(x int) { println() } // no report: function is address-taken
)

func _() {
	calledGlobal(1)
	println(addressTakenGlobal)
}

func Exported(unused int) {} // no finding: an exported function may be address-taken

type T int

func (T) m(_ bool) { println() } // want "unused parameter: f"
func (T) n(f bool) { println() } // no finding: n may match the interface method parent.n

func _() {
	var fib func(x, y int) int
	fib = func(x, _ int) int { // want "unused parameter: y"
		if x < 2 {
			return x
		}
		return fib(x-1, 123) + fib(x-2, 456)
	}
	fib(10, 42)
}


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/generatedcode/generatedcode.go
================================================
// Code generated with somegen DO NOT EDIT.
//
// Because this file is generated, there should be no diagnostics
// reported for any unused parameters.

package generatedcode

// generatedInterface exists to ensure that the generated code
// is considered when determining whether parameters are used
// in non-generated code.
type generatedInterface interface{ n(f bool) }

func a(x bool) { println() }

var v = func(x bool) { println() }


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/generatedcode/generatedcode.go.golden
================================================
// Code generated with somegen DO NOT EDIT.
//
// Because this file is generated, there should be no diagnostics
// reported for any unused parameters.

package generatedcode

// generatedInterface exists to ensure that the generated code
// is considered when determining whether parameters are used
// in non-generated code.
type generatedInterface interface{ n(f bool) }

func a(x bool) { println() }

var v = func(x bool) { println() }


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/generatedcode/nongeneratedcode.go
================================================
package generatedcode

// This file does not have the generated code comment.
// It exists to ensure that generated code is considered
// when determining whether or not function parameters
// are used.

type implementsGeneratedInterface struct{}

// The f parameter should not be reported as unused,
// because this method implements the parent interface defined
// in the generated code.
func (implementsGeneratedInterface) n(f bool) {
	// The body must not be empty, otherwise unusedparams will
	// not report the unused parameter regardless of the
	// interface.
	println()
}

func b(x bool) { println() } // want "unused parameter: x"


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/generatedcode/nongeneratedcode.go.golden
================================================
package generatedcode

// This file does not have the generated code comment.
// It exists to ensure that generated code is considered
// when determining whether or not function parameters
// are used.

type implementsGeneratedInterface struct{}

// The f parameter should not be reported as unused,
// because this method implements the parent interface defined
// in the generated code.
func (implementsGeneratedInterface) n(f bool) {
	// The body must not be empty, otherwise unusedparams will
	// not report the unused parameter regardless of the
	// interface.
	println()
}

func b(_ bool) { println() } // want "unused parameter: x"


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/typeparams/typeparams.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"bytes"
	"fmt"
	"net/http"
)

type parent[T any] interface {
	n(f T)
}

type yuh[T any] struct {
	a T
}

func (y *yuh[int]) n(f bool) {
	for i := 0; i < 10; i++ {
		fmt.Println(i)
	}
}

func a[T comparable](i1 int, i2 T, i3 int) int { // want "unused parameter: i2"
	i3 += i1
	_ = func(z int) int { // want "unused parameter: z"
		_ = 1
		return 1
	}
	return i3
}

func b[T any](c bytes.Buffer) { // want "unused parameter: c"
	_ = 1
}

func z[T http.ResponseWriter](h T, _ *http.Request) { // no report: func z is address-taken
	fmt.Println("Before")
}

func l(h http.Handler) http.Handler { // want "unused parameter: h"
	return http.HandlerFunc(z[http.ResponseWriter])
}

func mult(a, b int) int { // want "unused parameter: b"
	a += 1
	return a
}

func y[T any](a T) {
	panic("yo")
}


================================================
FILE: gopls/internal/analysis/unusedparams/testdata/src/typeparams/typeparams.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"bytes"
	"fmt"
	"net/http"
)

type parent[T any] interface {
	n(f T)
}

type yuh[T any] struct {
	a T
}

func (y *yuh[int]) n(f bool) {
	for i := 0; i < 10; i++ {
		fmt.Println(i)
	}
}

func a[T comparable](i1 int, _ T, i3 int) int { // want "unused parameter: i2"
	i3 += i1
	_ = func(_ int) int { // want "unused parameter: z"
		_ = 1
		return 1
	}
	return i3
}

func b[T any](_ bytes.Buffer) { // want "unused parameter: c"
	_ = 1
}

func z[T http.ResponseWriter](h T, _ *http.Request) { // no report: func z is address-taken
	fmt.Println("Before")
}

func l(_ http.Handler) http.Handler { // want "unused parameter: h"
	return http.HandlerFunc(z[http.ResponseWriter])
}

func mult(a, _ int) int { // want "unused parameter: b"
	a += 1
	return a
}

func y[T any](a T) {
	panic("yo")
}


================================================
FILE: gopls/internal/analysis/unusedparams/unusedparams.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedparams

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/util/moreslices"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "unusedparams",
	Doc:      analyzerutil.MustExtractDoc(doc, "unusedparams"),
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedparams",
}

const FixCategory = "unusedparams" // recognized by gopls ApplyFix

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// First find all "address-taken" functions.
	// We must conservatively assume that their parameters
	// are all required to conform to some signature.
	//
	// A named function is address-taken if it is somewhere
	// used not in call position:
	//
	//	f(...)		// not address-taken
	//      use(f)          // address-taken
	//
	// A literal function is address-taken if it is not
	// immediately bound to a variable, or if that variable is
	// used not in call position:
	//
	//    f := func() { ... }; f()     			used only in call position
	//    var f func(); f = func() { ...f()... }; f()     	ditto
	//    use(func() { ... })				address-taken
	//

	// Note: this algorithm relies on the assumption that the
	// analyzer is called only for the "widest" package for a
	// given file: that is, p_test in preference to p, if both
	// exist. Analyzing only package p may produce diagnostics
	// that would be falsified based on declarations in p_test.go
	// files. The gopls analysis driver does this, but most
	// drivers to not, so running this command in, say,
	// unitchecker or multichecker may produce incorrect results.

	// Gather global information:
	// - uses of functions not in call position
	// - unexported interface methods
	// - all referenced variables

	usesOutsideCall := make(map[types.Object][]*ast.Ident)
	unexportedIMethodNames := make(map[string]bool)
	{
		callPosn := make(map[*ast.Ident]bool) // all idents f appearing in f() calls
		filter := []ast.Node{
			(*ast.CallExpr)(nil),
			(*ast.InterfaceType)(nil),
		}
		inspect.Preorder(filter, func(n ast.Node) {
			switch n := n.(type) {
			case *ast.CallExpr:
				id := typesinternal.UsedIdent(pass.TypesInfo, n.Fun)
				// Find object:
				// record non-exported function, method, or func-typed var.
				if id != nil && !id.IsExported() {
					switch pass.TypesInfo.Uses[id].(type) {
					case *types.Func, *types.Var:
						callPosn[id] = true
					}
				}

			case *ast.InterfaceType:
				// Record the set of names of unexported interface methods.
				// (It would be more precise to record signatures but
				// generics makes it tricky, and this conservative
				// heuristic is close enough.)
				t := pass.TypesInfo.TypeOf(n).(*types.Interface)
				for m := range t.ExplicitMethods() {
					if !m.Exported() && m.Name() != "_" {
						unexportedIMethodNames[m.Name()] = true
					}
				}
			}
		})

		for id, obj := range pass.TypesInfo.Uses {
			if !callPosn[id] {
				// This includes "f = func() {...}", which we deal with below.
				usesOutsideCall[obj] = append(usesOutsideCall[obj], id)
			}
		}
	}

	// Find all vars (notably parameters) that are used.
	usedVars := make(map[*types.Var]bool)
	for _, obj := range pass.TypesInfo.Uses {
		if v, ok := obj.(*types.Var); ok {
			if v.IsField() {
				continue // no point gathering these
			}
			usedVars[v] = true
		}
	}

	// Check each non-address-taken function's parameters are all used.
funcloop:
	for c := range inspect.Root().Preorder((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)) {
		var (
			fn    types.Object // function symbol (*Func, possibly *Var for a FuncLit)
			ftype *ast.FuncType
			body  *ast.BlockStmt
		)
		switch n := c.Node().(type) {
		case *ast.FuncDecl:
			// We can't analyze non-Go functions.
			if n.Body == nil {
				continue
			}

			// Ignore exported functions and methods: we
			// must assume they may be address-taken in
			// another package.
			if n.Name.IsExported() {
				continue
			}

			// Ignore methods that match the name of any
			// interface method declared in this package,
			// as the method's signature may need to conform
			// to the interface.
			if n.Recv != nil && unexportedIMethodNames[n.Name.Name] {
				continue
			}

			fn = pass.TypesInfo.Defs[n.Name].(*types.Func)
			ftype, body = n.Type, n.Body

		case *ast.FuncLit:
			// Find the symbol for the variable (if any)
			// to which the FuncLit is bound.
			// (We don't bother to allow ParenExprs.)
			switch parent := c.Parent().Node().(type) {
			case *ast.AssignStmt:
				// f  = func() {...}
				// f := func() {...}
				if ek, idx := c.ParentEdge(); ek == edge.AssignStmt_Rhs {
					// Inv: n == AssignStmt.Rhs[idx]
					if id, ok := parent.Lhs[idx].(*ast.Ident); ok {
						fn = pass.TypesInfo.ObjectOf(id)

						// Edge case: f = func() {...}
						// should not count as a use.
						if pass.TypesInfo.Uses[id] != nil {
							usesOutsideCall[fn] = moreslices.Remove(usesOutsideCall[fn], id)
						}

						if fn == nil && id.Name == "_" {
							// Edge case: _ = func() {...}
							// has no local var. Fake one.
							v := types.NewVar(id.Pos(), pass.Pkg, id.Name, pass.TypesInfo.TypeOf(n))
							v.SetKind(types.LocalVar)
							fn = v
						}
					}
				}

			case *ast.ValueSpec:
				// var f = func() { ... }
				// (unless f is an exported package-level var)
				for i, val := range parent.Values {
					if val == n {
						v := pass.TypesInfo.Defs[parent.Names[i]]
						if !(v.Parent() == pass.Pkg.Scope() && v.Exported()) {
							fn = v
						}
						break
					}
				}
			}

			ftype, body = n.Type, n.Body
		}

		// Ignore address-taken functions and methods: unused
		// parameters may be needed to conform to a func type.
		if fn == nil || len(usesOutsideCall[fn]) > 0 {
			continue
		}

		// If there are no parameters, there are no unused parameters.
		if ftype.Params.NumFields() == 0 {
			continue
		}

		// To reduce false positives, ignore functions with an
		// empty or panic body.
		//
		// We choose not to ignore functions whose body is a
		// single return statement (as earlier versions did)
		// 	func f() { return }
		// 	func f() { return g(...) }
		// as we suspect that was just heuristic to reduce
		// false positives in the earlier unsound algorithm.
		switch len(body.List) {
		case 0:
			// Empty body. Although the parameter is
			// unnecessary, it's pretty obvious to the
			// reader that that's the case, so we allow it.
			continue // func f() {}
		case 1:
			if stmt, ok := body.List[0].(*ast.ExprStmt); ok {
				// We allow a panic body, as it is often a
				// placeholder for a future implementation:
				// 	func f() { panic(...) }
				if call, ok := stmt.X.(*ast.CallExpr); ok {
					if fun, ok := call.Fun.(*ast.Ident); ok && fun.Name == "panic" {
						continue
					}
				}
			}
		}

		// Don't report diagnostics on generated files.
		// (We can't skip analysis of generated files, though.)
		if ast.IsGenerated(astutil.EnclosingFile(c)) {
			continue funcloop
		}

		// Report each unused parameter.
		for _, field := range ftype.Params.List {
			for _, id := range field.Names {
				if id.Name == "_" {
					continue
				}
				param := pass.TypesInfo.Defs[id].(*types.Var)
				if !usedVars[param] {
					start, end := field.Pos(), field.End()
					if len(field.Names) > 1 {
						start, end = id.Pos(), id.End()
					}

					// This diagnostic carries both an edit-based fix to
					// rename the unused parameter, and a command-based fix
					// to remove it (see golang.RemoveUnusedParameter).
					pass.Report(analysis.Diagnostic{
						Pos:      start,
						End:      end,
						Message:  fmt.Sprintf("unused parameter: %s", id.Name),
						Category: FixCategory,
						SuggestedFixes: []analysis.SuggestedFix{
							{
								Message: `Rename parameter to "_"`,
								TextEdits: []analysis.TextEdit{{
									Pos:     id.Pos(),
									End:     id.End(),
									NewText: []byte("_"),
								}},
							},
							{
								Message: fmt.Sprintf("Remove unused parameter %q", id.Name),
								// No TextEdits => computed by gopls command
							},
						},
					})
				}
			}
		}
	}
	return nil, nil
}


================================================
FILE: gopls/internal/analysis/unusedparams/unusedparams_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedparams_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/unusedparams"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.RunWithSuggestedFixes(t, testdata, unusedparams.Analyzer, "a", "generatedcode", "typeparams")
}


================================================
FILE: gopls/internal/analysis/unusedvariable/testdata/src/assign/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"fmt"
	"os"
)

type A struct {
	b int
}

func singleAssignment() {
	v := "s" // want `declared (and|but) not used`

	s := []int{ // want `declared (and|but) not used`
		1,
		2,
	}

	a := func(s string) bool { // want `declared (and|but) not used`
		return false
	}

	if 1 == 1 {
		s := "v" // want `declared (and|but) not used`
	}

	panic("I should survive")
}

func noOtherStmtsInBlock() {
	v := "s" // want `declared (and|but) not used`
}

func partOfMultiAssignment() {
	f, err := os.Open("file") // want `declared (and|but) not used`
	panic(err)
}

func sideEffects(cBool chan bool, cInt chan int) {
	b := <-c            // want `declared (and|but) not used`
	s := fmt.Sprint("") // want `declared (and|but) not used`
	a := A{             // want `declared (and|but) not used`
		b: func() int {
			return 1
		}(),
	}
	c := A{<-cInt}          // want `declared (and|but) not used`
	d := fInt() + <-cInt    // want `declared (and|but) not used`
	e := fBool() && <-cBool // want `declared (and|but) not used`
	f := map[int]int{       // want `declared (and|but) not used`
		fInt(): <-cInt,
	}
	g := []int{<-cInt}     // want `declared (and|but) not used`
	h := func(s string) {} // want `declared (and|but) not used`

	// (ill-typed)
	i := func(s string) {}() // want `declared (and|but) not used`
}

func commentAbove() {
	// v is a variable
	v := "s" // want `declared (and|but) not used`
}

func commentBelow() {
	v := "s" // want `declared (and|but) not used`
	// v is a variable
}

func commentSpaceBelow() {
	v := "s" // want `declared (and|but) not used`

	// v is a variable
}

func fBool() bool {
	return true
}

func fInt() int {
	return 1
}


================================================
FILE: gopls/internal/analysis/unusedvariable/testdata/src/assign/a.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"fmt"
	"os"
)

type A struct {
	b int
}

func singleAssignment() {



	if 1 == 1 {
	}

	panic("I should survive")
}

func noOtherStmtsInBlock() {
}

func partOfMultiAssignment() {
	_, err := os.Open("file") // want `declared (and|but) not used`
	panic(err)
}

func sideEffects(cBool chan bool, cInt chan int) {
	_ = <-c            // want `declared (and|but) not used`
	_ = fmt.Sprint("") // want `declared (and|but) not used`
	_ = A{             // want `declared (and|but) not used`
		b: func() int {
			return 1
		}(),
	}
	_ = A{<-cInt}          // want `declared (and|but) not used`
	_ = fInt() + <-cInt    // want `declared (and|but) not used`
	_ = fBool() && <-cBool // want `declared (and|but) not used`
	_ = map[int]int{       // want `declared (and|but) not used`
		fInt(): <-cInt,
	}
	_ = []int{<-cInt}       // want `declared (and|but) not used`

	// (ill-typed)
	_ = func(s string) {}() // want `declared (and|but) not used`
}

func commentAbove() {
	// v is a variable
}

func commentBelow() {
	// v is a variable
}

func commentSpaceBelow() {

	// v is a variable
}

func fBool() bool {
	return true
}

func fInt() int {
	return 1
}


================================================
FILE: gopls/internal/analysis/unusedvariable/testdata/src/decl/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package decl

func a() {
	var b, c bool // want `declared (and|but) not used`
	panic(c)

	if 1 == 1 {
		var s string // want `declared (and|but) not used`
	}
}

func b() {
	// b is a variable
	var b bool // want `declared (and|but) not used`
}

func c() {
	var (
		d string

		// some comment for c
		c bool // want `declared (and|but) not used`
	)

	panic(d)
}


================================================
FILE: gopls/internal/analysis/unusedvariable/testdata/src/decl/a.go.golden
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package decl

func a() {
	var c bool // want `declared (and|but) not used`
	panic(c)

	if 1 == 1 {
	}
}

func b() {
	// b is a variable
}

func c() {
	var (
		d string
	)
	
	panic(d)
}


================================================
FILE: gopls/internal/analysis/unusedvariable/unusedvariable.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package unusedvariable defines an analyzer that checks for unused variables.
package unusedvariable

import (
	"fmt"
	"go/ast"
	"regexp"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/refactor"
)

const Doc = `check for unused variables and suggest fixes`

var Analyzer = &analysis.Analyzer{
	Name:             "unusedvariable",
	Doc:              Doc,
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	Run:              run,
	RunDespiteErrors: true, // an unusedvariable diagnostic is a compile error
	URL:              "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedvariable",
}

// The suffix for this error message changed in Go 1.20 and Go 1.23.
var unusedVariableRegexp = []*regexp.Regexp{
	regexp.MustCompile("^(.*) declared and not used$"),  // Go 1.20+
	regexp.MustCompile("^declared and not used: (.*)$"), // Go 1.23+
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	for _, typeErr := range pass.TypeErrors {
		for _, re := range unusedVariableRegexp {
			match := re.FindStringSubmatch(typeErr.Msg)
			if len(match) == 0 {
				continue
			}
			// Since Go 1.23, go/types' error messages quote vars as `v'.
			varName := strings.Trim(match[1], "`'")

			curId, ok := inspect.Root().FindByPos(typeErr.Pos, typeErr.Pos)
			if !ok {
				continue // can't find error node
			}
			ident, ok := curId.Node().(*ast.Ident)
			if !ok || ident.Name != varName {
				continue // not the right identifier
			}

			tokFile := pass.Fset.File(ident.Pos())
			edits := refactor.DeleteVar(tokFile, pass.TypesInfo, curId)
			if len(edits) > 0 {
				pass.Report(analysis.Diagnostic{
					Pos:     ident.Pos(),
					End:     ident.End(),
					Message: typeErr.Msg,
					SuggestedFixes: []analysis.SuggestedFix{{
						Message:   fmt.Sprintf("Remove variable %s", ident.Name),
						TextEdits: edits,
					}},
				})
			}
		}
	}

	return nil, nil
}


================================================
FILE: gopls/internal/analysis/unusedvariable/unusedvariable_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package unusedvariable_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/unusedvariable"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()

	t.Run("decl", func(t *testing.T) {
		analysistest.RunWithSuggestedFixes(t, testdata, unusedvariable.Analyzer, "decl")
	})

	t.Run("assign", func(t *testing.T) {
		analysistest.RunWithSuggestedFixes(t, testdata, unusedvariable.Analyzer, "assign")
	})
}


================================================
FILE: gopls/internal/analysis/writestring/doc.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package writestring defines an Analyzer that detects
// inefficient string concatenation in uses of WriteString.
//
// # Analyzer writestring
//
// writestring: detect inefficient string concatenation in uses of WriteString
//
// The writestring analyzer offers to replace a call to WriteString(x + y) by
// two calls WriteString(x); WriteString(y). This is more efficient because it
// avoids the additional memory allocation produced by string concatenation;
// instead we just write each string into the buffer directly.
//
// It explicitly looks for calls to certain well-known writers such as
// bytes.Buffer, strings.Builder and bufio.Writer. The analyzer will not suggest
// a fix for calls to, say, (*os.File).WriteString, because for certain kinds of
// file such as a UDP socket, it could split a single message into two.
// Similarly it does not offer fixes when the type of the writer is unknown (as
// in calls to io.WriteString).
//
// For example:
//
//	func f(a string, b string) string {
//		 var s strings.Builder
//		 s.WriteString(a+b)
//		 return s.String()
//	}
//
// would become:
//
//	func f(a string, b string) string {
//		var s strings.Builder
//		s.WriteString(a)
//		s.WriteString(b)
//		return s.String()
//	}
package writestring


================================================
FILE: gopls/internal/analysis/writestring/main.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The writestring command applies the golang.org/x/tools/go/analysis/passes/writestring
// analysis to the specified packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/passes/writestring"
	"golang.org/x/tools/go/analysis/singlechecker"
)

func main() { singlechecker.Main(writestring.Analyzer) }


================================================
FILE: gopls/internal/analysis/writestring/testdata/src/a/a.go
================================================
package a

import (
	"bufio"
	"bytes"
	"hash/maphash"
	"os"
	"strings"
)

func _(v string) {
	var s strings.Builder
	a := "a"
	b := "b"
	s.WriteString(a + b) // want "Inefficient string concatenation in call to WriteString"

	var p *string
	s.WriteString(a + ("b" + *p)) // want "Inefficient string concatenation in call to WriteString"

	type S struct{ B bytes.Buffer }
	var sb S
	sb.B.WriteString(a + b) // want "Inefficient string concatenation in call to WriteString"

	var bufw bufio.Writer
	const k = "k"
	bufw.WriteString(a + getString() + "b") // want "Inefficient string concatenation in call to WriteString"
	bufw.WriteString(k + "b" + v + "c")     // want "Inefficient string concatenation in call to WriteString"

	var h maphash.Hash
	h.WriteString(a + b) // want "Inefficient string concatenation in call to WriteString"

	var buf bytes.Buffer
	buf.WriteString(a)            // nope - nothing to extract
	buf.WriteString("a" + "b")    // nope - no need to split because the concatenation is resolved without allocations
	f(buf.WriteString(a + b))     // nope - inside function call
	_, _ = buf.WriteString(a + b) // nope - inside assignment
	getBuf().WriteString(a + b)   // nope - function call in receiver
	var bufs []bytes.Buffer
	bufs[getIndex()].WriteString(a + b) // nope - index expression in receiver

	var f *os.File
	f.WriteString(a + b) // nope - os.File is not an allowed writer for this analyzer
}

func f(i int, err error) {}

func getIndex() int {
	return 0
}

func getString() string {
	return "string"
}

func getBuf() *bytes.Buffer { return &bytes.Buffer{} }


================================================
FILE: gopls/internal/analysis/writestring/testdata/src/a/a.go.golden
================================================
package a

import (
	"bufio"
	"bytes"
	"hash/maphash"
	"os"
	"strings"
)

func _(v string) {
	var s strings.Builder
	a := "a"
	b := "b"
	s.WriteString(a)
	s.WriteString(b) // want "Inefficient string concatenation in call to WriteString"

	var p *string
	s.WriteString(a)
	s.WriteString("b")
	s.WriteString(*p) // want "Inefficient string concatenation in call to WriteString"

	type S struct{ B bytes.Buffer }
	var sb S
	sb.B.WriteString(a)
	sb.B.WriteString(b) // want "Inefficient string concatenation in call to WriteString"

	var bufw bufio.Writer
	const k = "k"
	bufw.WriteString(a)
	bufw.WriteString(getString())
	bufw.WriteString("b") // want "Inefficient string concatenation in call to WriteString"
	bufw.WriteString(k + "b")
	bufw.WriteString(v)
	bufw.WriteString("c") // want "Inefficient string concatenation in call to WriteString"

	var h maphash.Hash
	h.WriteString(a)
	h.WriteString(b) // want "Inefficient string concatenation in call to WriteString"

	var buf bytes.Buffer
	buf.WriteString(a)            // nope - nothing to extract
	buf.WriteString("a" + "b")    // nope - no need to split because the concatenation is resolved without allocations
	f(buf.WriteString(a + b))     // nope - inside function call
	_, _ = buf.WriteString(a + b) // nope - inside assignment
	getBuf().WriteString(a + b)   // nope - function call in receiver
	var bufs []bytes.Buffer
	bufs[getIndex()].WriteString(a + b) // nope - index expression in receiver

	var f *os.File
	f.WriteString(a + b) // nope - os.File is not an allowed writer for this analyzer
}

func f(i int, err error) {}

func getIndex() int {
	return 0
}

func getString() string {
	return "string"
}

func getBuf() *bytes.Buffer { return &bytes.Buffer{} }



================================================
FILE: gopls/internal/analysis/writestring/writestring.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package writestring defines an Analyzer that detects
// inefficient string concatenation in uses of WriteString.
package writestring

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/analyzerutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "writestring",
	Doc:      analyzerutil.MustExtractDoc(doc, "writestring"),
	URL:      "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/writestring",
	Requires: []*analysis.Analyzer{inspect.Analyzer},
	Run:      run,
}

func run(pass *analysis.Pass) (any, error) {
	inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	for curCall := range inspect.Root().Preorder((*ast.CallExpr)(nil)) {
		call := curCall.Node().(*ast.CallExpr)
		info := pass.TypesInfo
		callee := typeutil.Callee(info, call)
		if callee == nil || callee.Name() != "WriteString" {
			continue
		}

		// We intervene only for io.Writer types where we know that WriteString
		// is cheap and distributes over string concatenation.
		// (This is not the case for, say, file descriptors, where each write
		// is expensive, and splitting one UDP write into two is a behavior change.)
		// TODO(mkalil): This doesn't detect calls to aliases of w.WriteString.
		// I think it's okay to skip that case because it's uncommon and also
		// would increase the complexity to determine the type of the writer.
		if !(typesinternal.IsMethodNamed(callee, "strings", "Builder", "WriteString") ||
			typesinternal.IsMethodNamed(callee, "bytes", "Buffer", "WriteString") ||
			typesinternal.IsMethodNamed(callee, "bufio", "Writer", "WriteString") ||
			typesinternal.IsMethodNamed(callee, "hash/maphash", "Hash", "WriteString")) {
			continue
		}

		// curCall must be a standalone statement. We skip calls used in
		// assignments, control flow expressions, or defer/go statements, since
		// splitting them requires complex rewriting of the surrounding logic.
		if curCall.ParentEdgeKind() != edge.ExprStmt_X {
			continue
		}

		// Check that the receiver "w" in the call to w.WriteString has no side
		// effects. For example, if the receiver involves some function call F,
		// we cannot suggest a fix because duplicate calls to F may result in
		// unintended behavior.
		// returnsBuffer().WriteString(...) --> reject
		// a.B.w.WriteString(...) --> ok
		if !typesinternal.NoEffects(info, call.Fun) {
			continue
		}

		if len(call.Args) != 1 {
			continue // can't happen
		}
		arg := call.Args[0]
		if _, ok := arg.(*ast.BinaryExpr); !ok {
			continue
		}

		operands := stringConcatenands(info, arg)
		if len(operands) < 2 {
			continue
		}

		// Format the separate WriteString calls.
		var newStmts []string
		for _, operand := range operands {
			stmt := fmt.Sprintf("%s(%s)",
				astutil.Format(pass.Fset, call.Fun),
				astutil.Format(pass.Fset, operand))
			newStmts = append(newStmts, stmt)
		}
		replacement := strings.Join(newStmts, ";")

		pass.Report(analysis.Diagnostic{
			Pos:     call.Pos(),
			End:     call.End(),
			Message: "Inefficient string concatenation in call to WriteString",
			SuggestedFixes: []analysis.SuggestedFix{{
				Message: "Split into separate WriteString calls",
				TextEdits: []analysis.TextEdit{{
					Pos:     call.Pos(),
					End:     call.End(),
					NewText: []byte(replacement),
				}},
			}},
		})
	}
	return nil, nil
}

// stringConcatenands flattens a string concatenation expression expr
// (e.g., "a" + "b" + c) into a sequence of individual operands. It combines
// adjacent constants or basic literals, whose combined value evaluates to a
// constant, into a single expression. For example, "a" + k + v would return
// [("a" + k), v]. Writing k and "a" separately would be a de-optimization, as
// we already evaluate the value of this expression at compile time. If the
// expression cannot be safely flattened, it returns nil.
func stringConcatenands(info *types.Info, expr ast.Expr) (operands []ast.Expr) {
	if info.Types[expr].Value != nil {
		return []ast.Expr{expr}
	}
	if bin, ok := ast.Unparen(expr).(*ast.BinaryExpr); ok {
		if bin.Op != token.ADD {
			// Valid Go code only allows string concatenation via the add
			// operator.
			panic("invalid concatenation operator")
		}
		opsX := stringConcatenands(info, bin.X)
		if opsX == nil {
			return nil
		}
		opsY := stringConcatenands(info, bin.Y)
		if opsY == nil {
			return nil
		}
		return append(opsX, opsY...)
	}
	return []ast.Expr{expr}
}


================================================
FILE: gopls/internal/analysis/writestring/writestring_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package writestring_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/writestring"
)

func Test(t *testing.T) {
	analysistest.RunWithSuggestedFixes(t, analysistest.TestData(), writestring.Analyzer, "a")
}


================================================
FILE: gopls/internal/analysis/yield/doc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package yield defines an Analyzer that checks for mistakes related
// to the yield function used in iterators.
//
// # Analyzer yield
//
// yield: report calls to yield where the result is ignored
//
// After a yield function returns false, the caller should not call
// the yield function again; generally the iterator should return
// promptly.
//
// This example fails to check the result of the call to yield,
// causing this analyzer to report a diagnostic:
//
//	yield(1) // yield may be called again (on L2) after returning false
//	yield(2)
//
// The corrected code is either this:
//
//	if yield(1) { yield(2) }
//
// or simply:
//
//	_ = yield(1) && yield(2)
//
// It is not always a mistake to ignore the result of yield.
// For example, this is a valid single-element iterator:
//
//	yield(1) // ok to ignore result
//	return
//
// It is only a mistake when the yield call that returned false may be
// followed by another call.
package yield


================================================
FILE: gopls/internal/analysis/yield/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The yield command applies the yield analyzer to the specified
// packages of Go source code.
package main

import (
	"golang.org/x/tools/go/analysis/singlechecker"
	"golang.org/x/tools/gopls/internal/analysis/yield"
)

func main() { singlechecker.Main(yield.Analyzer) }


================================================
FILE: gopls/internal/analysis/yield/testdata/src/a/a.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package yield

import (
	"bufio"
	"io"
	"iter"
	"runtime"
)

// Modify this block of comment lines as needed when changing imports
// to avoid perturbing subsequent line numbers (and thus error messages).
//
// This is L16.

func goodIter(yield func(int) bool) {
	_ = yield(1) && yield(2) && yield(3) // ok
}

func badIterOR(yield func(int) bool) {
	_ = yield(1) || // want `yield may be called again \(on L25\) after returning false`
		yield(2) || // want `yield may be called again \(on L26\) after returning false`
		yield(3)
}

func badIterSeq(yield func(int) bool) {
	yield(1) // want `yield may be called again \(on L31\) after returning false`
	yield(2) // want `yield may be called again \(on L32\) after returning false`
	yield(3) // ok
}

func badIterLoop(yield func(int) bool) {
	for {
		yield(1) // want `yield may be called again after returning false`
	}
}

func goodIterLoop(yield func(int) bool) {
	for {
		if !yield(1) {
			break
		}
	}
}

func badIterIf(yield func(int) bool) {
	ok := yield(1) // want `yield may be called again \(on L52\) after returning false`
	if !ok {
		yield(2)
	} else {
		yield(3)
	}
}

func singletonIter(yield func(int) bool) {
	yield(1) // ok
}

func twoArgumentYield(yield func(int, int) bool) {
	_ = yield(1, 1) || // want `yield may be called again \(on L64\) after returning false`
		yield(2, 2)
}

func zeroArgumentYield(yield func() bool) {
	_ = yield() || // want `yield may be called again \(on L69\) after returning false`
		yield()
}

func tricky(in io.ReadCloser) func(yield func(string, error) bool) {
	return func(yield func(string, error) bool) {
		scan := bufio.NewScanner(in)
		for scan.Scan() {
			if !yield(scan.Text(), nil) { // want `yield may be called again \(on L82\) after returning false`
				_ = in.Close()
				break
			}
		}
		if err := scan.Err(); err != nil {
			yield("", err)
		}
	}
}

// Regression test for issue #70598.
func shortCircuitAND(yield func(int) bool) {
	ok := yield(1)
	ok = ok && yield(2)
	ok = ok && yield(3)
	ok = ok && yield(4)
}

// This example has a bug because a false yield(2) may be followed by yield(3).
func tricky2(yield func(int) bool) {
	cleanup := func() {}
	ok := yield(1)          // want "yield may be called again .on L104"
	stop := !ok || yield(2) // want "yield may be called again .on L104"
	if stop {
		cleanup()
	} else {
		// dominated by !stop => !(!ok || yield(2)) => yield(1) && !yield(2): bad.
		yield(3)
	}
}

// This case from issue #74136 is sound, and should produce no diagnostic.
func tricky3(yield func(int) bool) {
	cleanup := func() {}
	ok := yield(1)
	stop := !ok || !yield(2)
	if stop {
		cleanup()
	} else {
		// dominated by !stop => !(!ok || !yield(2)) => yield(1) && yield(2): good.
		yield(3)
	}
}

// So is this one, from issue #75924
func tricky5(list []string, cond bool) iter.Seq[string] {
	return func(yield func(string) bool) {
		for _, s := range list {
			var ok bool
			if cond {
				ok = yield(s)
			} else {
				ok = yield(s)
			}
			if !ok {
				return
			}
		}
	}
}

// This one is from the tests of the "iter" package.
func tricky6() iter.Seq[int] {
	return func(yield func(int) bool) {
		for {
			if !yield(55) { // nope
				runtime.Goexit()
			}
		}
	}
}

// Regression test for issue #77681. A boolean switch is now
// handled just like an if/else chain in the SSA builder.
func switchShortCircuit(seq iter.Seq[int]) iter.Seq[int] {
	return func(yield func(int) bool) {
		for item := range seq {
			isZero := item == 0
			switch {
			case !isZero && !yield(item): // ok
				return
			case !isZero:
				continue
			case !yield(0): // ok
				return
			}
		}
	}
}


================================================
FILE: gopls/internal/analysis/yield/yield.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package yield

// TODO(adonovan): also check for this pattern:
//
// 	for x := range seq {
// 		yield(x)
// 	}
//
// which should be entirely rewritten as
//
// 	seq(yield)
//
// to avoid unnecessary range desugaring and chains of dynamic calls.

import (
	_ "embed"
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"iter"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/buildssa"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/ssa"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/analysis/analyzerutil"
)

//go:embed doc.go
var doc string

var Analyzer = &analysis.Analyzer{
	Name:     "yield",
	Doc:      analyzerutil.MustExtractDoc(doc, "yield"),
	Requires: []*analysis.Analyzer{inspect.Analyzer, buildssa.Analyzer},
	Run:      run,
	URL:      "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/yield",
}

func run(pass *analysis.Pass) (any, error) {
	inspector := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)

	// Find all calls to yield of the right type.
	yieldCalls := make(map[token.Pos]*ast.CallExpr) // keyed by CallExpr.Lparen.
	nodeFilter := []ast.Node{(*ast.CallExpr)(nil)}
	inspector.Preorder(nodeFilter, func(n ast.Node) {
		call := n.(*ast.CallExpr)
		if id, ok := call.Fun.(*ast.Ident); ok && id.Name == "yield" {
			if sig, ok := pass.TypesInfo.TypeOf(id).(*types.Signature); ok &&
				sig.Params().Len() < 3 &&
				sig.Results().Len() == 1 &&
				types.Identical(sig.Results().At(0).Type(), types.Typ[types.Bool]) {
				yieldCalls[call.Lparen] = call
			}
		}
	})

	// Common case: nothing to do.
	if len(yieldCalls) == 0 {
		return nil, nil
	}

	// Study the control flow using SSA.
	buildssa := pass.ResultOf[buildssa.Analyzer].(*buildssa.SSA)
	for _, fn := range buildssa.SrcFuncs {
		// TODO(adonovan): opt: skip functions that don't contain any yield calls.

		// Find the yield calls in SSA.
		type callInfo struct {
			syntax   *ast.CallExpr
			index    int // index of instruction within its block
			reported bool
		}
		ssaYieldCalls := make(map[*ssa.Call]*callInfo)
		for _, b := range fn.Blocks {
			for i, instr := range b.Instrs {
				if call, ok := instr.(*ssa.Call); ok {
					if syntax, ok := yieldCalls[call.Pos()]; ok {
						ssaYieldCalls[call] = &callInfo{syntax: syntax, index: i}
					}
				}
			}
		}
		isYieldCall := func(v ssa.Value) bool {
			call, ok := v.(*ssa.Call)
			return ok && ssaYieldCalls[call] != nil
		}

		// Now search for a control path from the instruction after a
		// yield call to another yield call--possible the same one,
		// following all block successors except "if yield() { ... }";
		// in such cases we know that yield returned true.
		//
		// Note that this is a "may" dataflow analysis: it
		// reports when a yield function _may_ be called again
		// without a positive intervening check, but it is
		// possible that the check is beyond the ability of
		// the representation to detect, perhaps involving
		// sophisticated use of booleans, indirect state (not
		// in SSA registers), or multiple flow paths some of
		// which are infeasible.
		//
		// A "must" analysis (which would report when a second
		// yield call can only be reached after failing the
		// boolean check) would be too conservative.
		// In particular, the most common mistake is to
		// forget to check the boolean at all.
		for call, info := range ssaYieldCalls {
			visited := make([]bool, len(fn.Blocks)) // visited BasicBlock.Indexes

			// visit visits the instructions of a block (or a suffix if start > 0).
			var visit func(b *ssa.BasicBlock, start int)
			visit = func(b *ssa.BasicBlock, start int) {
				if visited[b.Index] {
					return
				}
				if start == 0 {
					visited[b.Index] = true
				}
				for _, instr := range b.Instrs[start:] {
					switch instr := instr.(type) {
					case *ssa.Call:

						// Precondition: v has a pos within a CallExpr.
						enclosingCall := func(v ssa.Value) ast.Node {
							pos := v.Pos()
							cur, ok := inspector.Root().FindByPos(pos, pos)
							if !ok {
								panic(fmt.Sprintf("can't find node at %v", safetoken.StartPosition(pass.Fset, pos)))
							}
							call, _ := cursorutil.FirstEnclosing[*ast.CallExpr](cur)
							if call == nil {
								panic(fmt.Sprintf("no call enclosing %v", safetoken.StartPosition(pass.Fset, pos)))
							}
							return call
						}

						if !info.reported && ssaYieldCalls[instr] != nil {
							info.reported = true
							var (
								where   = "" // "" => same yield call (a loop)
								related []analysis.RelatedInformation
							)
							// Also report location of reached yield call, if distinct.
							if instr != call {
								otherLine := safetoken.StartPosition(pass.Fset, instr.Pos()).Line
								where = fmt.Sprintf("(on L%d) ", otherLine)
								otherCallExpr := enclosingCall(instr)
								related = []analysis.RelatedInformation{{
									Pos:     otherCallExpr.Pos(),
									End:     otherCallExpr.End(),
									Message: "other call here",
								}}
							}
							callExpr := enclosingCall(call)
							pass.Report(analysis.Diagnostic{
								Pos:     callExpr.Pos(),
								End:     callExpr.End(),
								Message: fmt.Sprintf("yield may be called again %safter returning false", where),
								Related: related,
							})
						}
					case *ssa.If:
						// Visit both successors, unless cond is yield() or its negation.
						// In that case visit only the "if !yield()" block.
						t, f := reachableSuccs(instr.Cond, isYieldCall)
						if t {
							visit(b.Succs[0], 0)
						}
						if f {
							visit(b.Succs[1], 0)
						}

					case *ssa.Jump:
						visit(b.Succs[0], 0)
					}
				}
			}

			// Start at the instruction after the yield call.
			visit(call.Block(), info.index+1)
		}
	}

	return nil, nil
}

// reachableSuccs reports whether the (true, false) outcomes of the
// condition are possible.
func reachableSuccs(cond ssa.Value, isYieldCall func(ssa.Value) bool) (_t, _f bool) {
	// If the condition is...
	//
	// ...a constant, we know only one successor is reachable.
	//
	// ...a yield call, we assume that it returned false,
	// and treat it like a constant.
	//
	// ...a negation !v, we strip the negation and flip the sense
	// of the result.
	//
	// ...a phi node, we recursively find all non-phi leaves
	// of the phi graph and treat them like a conjunction,
	// e.g. if false || true || yield || yield { ... }.
	//
	// (We don't actually analyze || and && in this way,
	// but we could do them too.)

	// This logic addresses cases where conditions are
	// materialized as booleans such as this
	//
	//   ok := yield()
	//   ok = ok && yield()
	//   ok = ok && yield()
	//
	// which in SSA becomes:
	//
	//   yield()
	//   phi(false, yield())
	//   phi(false, yield())
	//
	// and we can reduce each phi(false, x) to just x.
	//
	// Similarly this case:
	//
	//	var ok bool
	//	if foo { ok = yield() }
	//	else   { ok = yield() }
	//	if ok { ... }
	//
	// can be analyzed as "if yield || yield".

	// all[false] => all cases are false
	// all[true]  => all cases are true
	all := [2]bool{true, true}
	for v := range unphi(cond) {
		sense := 1 // 0=false 1=true

		// Strip off any NOT operators.
		for {
			unop, ok := v.(*ssa.UnOp)
			if !(ok && unop.Op == token.NOT) {
				break
			}
			v = unop.X
			sense = 1 - sense
		}

		switch {
		case is[*ssa.Const](v):
			// "if false" means not all cases are true,
			// and vice versa.
			if constant.BoolVal(v.(*ssa.Const).Value) {
				sense = 1 - sense
			}
			all[sense] = false

		case isYieldCall(v):
			// "if yield" is assumed to be false.
			all[sense] = false // ¬ all cases are true

		default:
			// Unknown condition:
			// ¬ all cases are false
			// ¬ all cases are true
			return true, true
		}
	}
	if all[0] && all[1] {
		panic("unphi returned empty sequence")
	}
	return !all[0], !all[1]
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

// -- SSA helpers --

// unphi returns the sequence of values formed by recursively
// replacing phi nodes in v by their non-phi operands.
func unphi(v ssa.Value) iter.Seq[ssa.Value] {
	return func(yield func(ssa.Value) bool) {
		_ = every(v, yield)
	}
}

// every reports whether predicate f is true of each value in the
// sequence formed by recursively replacing phi nodes in v by their
// operands.
func every(v ssa.Value, f func(ssa.Value) bool) bool {
	var seen map[*ssa.Phi]bool
	var visit func(v ssa.Value) bool
	visit = func(v ssa.Value) bool {
		if phi, ok := v.(*ssa.Phi); ok {
			if !seen[phi] {
				if seen == nil {
					seen = make(map[*ssa.Phi]bool)
				}
				seen[phi] = true
				for _, edge := range phi.Edges {
					if !visit(edge) {
						return false
					}
				}
			}
			return true
		}
		return f(v)
	}
	return visit(v)
}


================================================
FILE: gopls/internal/analysis/yield/yield_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package yield_test

import (
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/gopls/internal/analysis/yield"
)

func Test(t *testing.T) {
	testdata := analysistest.TestData()
	analysistest.Run(t, testdata, yield.Analyzer, "a")
}


================================================
FILE: gopls/internal/bloom/filter.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bloom

import (
	"hash/maphash"
	"math"
)

// block is the element type of the filter bitfield.
type block = uint8

const blockBits = 8

// Filter is a bloom filter for a set of strings.
type Filter struct {
	seeds  []maphash.Seed
	blocks []block
}

// NewFilter constructs a new Filter with the given elements.
func NewFilter(elems []string) *Filter {
	// Tolerate a 5% false positive rate.
	nblocks, nseeds := calibrate(0.05, len(elems))
	f := &Filter{
		blocks: make([]block, nblocks),
		seeds:  make([]maphash.Seed, nseeds),
	}
	for i := range nseeds {
		f.seeds[i] = maphash.MakeSeed()
	}
	for _, elem := range elems {
		for _, seed := range f.seeds {
			index, bit := f.locate(seed, elem)
			f.blocks[index] |= bit
		}
	}
	return f
}

// locate returns the block index and bit corresponding to the given hash seed and
// string.
func (f *Filter) locate(seed maphash.Seed, s string) (index int, bit block) {
	h := uint(maphash.String(seed, s))
	blk := h / blockBits % uint(len(f.blocks))
	bit = block(1 << (h % blockBits))
	return int(blk), bit
}

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

// calibrate approximates the number of blocks and seeds to use for a bloom
// filter with desired false positive rate fpRate, given n elements.
func calibrate(fpRate float64, n int) (blocks, seeds int) {
	// We following the terms of https://en.wikipedia.org/wiki/Bloom_filter:
	// - k is the number of hash functions,
	// - m is the size of the bit field;
	// - n is the number of set bits.

	assert(0 < fpRate && fpRate < 1, "invalid false positive rate")
	assert(n >= 0, "invalid set size")

	if n == 0 {
		// degenerate case; use the simplest filter
		return 1, 1
	}

	// Calibrate the number of blocks based on the optimal number of bits per
	// element. In this case we round up, as more bits leads to fewer false
	// positives.
	logFpRate := math.Log(fpRate) // reused for k below
	m := -(float64(n) * logFpRate) / (math.Ln2 * math.Ln2)
	blocks = int(m) / blockBits
	if float64(blocks*blockBits) < m {
		blocks += 1
	}

	// Estimate the number of hash functions (=seeds). This is imprecise, not
	// least since the formula in the article above assumes that the number of
	// bits per element is not rounded.
	//
	// Here we round to the nearest integer (not unconditionally round up), since
	// more hash functions do not always lead to better results.
	k := -logFpRate / math.Ln2
	seeds = max(int(math.Round(k)), 1)

	return blocks, seeds
}

// MayContain reports whether the filter may contain s.
func (f *Filter) MayContain(s string) bool {
	for _, seed := range f.seeds {
		index, bit := f.locate(seed, s)
		if f.blocks[index]&bit == 0 {
			return false
		}
	}
	return true
}


================================================
FILE: gopls/internal/bloom/filter_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bloom

import (
	"math"
	"math/rand/v2"
	"testing"
)

func TestFilter(t *testing.T) {
	elems := []string{
		"a", "apple", "b", "banana", "an arbitrarily long string", "", "世界",
	}

	// First, sanity check that the filter contains all the given elements.
	f := NewFilter(elems)
	for _, elem := range elems {
		if got := f.MayContain(elem); !got {
			t.Errorf("MayContain(%q) = %t, want true", elem, got)
		}
	}

	// Measure the false positives rate.
	//
	// Of course, we can't assert on the results, since they are probabilistic,
	// but this can be useful for interactive use.

	fpRate := falsePositiveRate(len(f.blocks), len(f.seeds), len(elems))
	t.Logf("%d blocks, %d seeds, %.2g%% expected false positives", len(f.blocks), len(f.seeds), 100*fpRate)

	// In practice, all positives below will be false, but be precise anyway.
	truePositive := make(map[string]bool)
	for _, e := range elems {
		truePositive[e] = true
	}

	// Generate a large number of random strings to measure the false positive
	// rate.
	g := newStringGenerator()
	const samples = 1000
	falsePositives := 0
	for range samples {
		s := g.next()
		got := f.MayContain(s)
		if false {
			t.Logf("MayContain(%q) = %t", s, got)
		}
		if got && !truePositive[s] {
			falsePositives++
		}
	}
	t.Logf("false positives: %.1f%% (%d/%d)", 100*float64(falsePositives)/float64(samples), falsePositives, samples)
}

// falsePositiveRate estimates the expected false positive rate for a filter
// with the given number of blocks, seeds, and elements.
func falsePositiveRate(block, seeds, elems int) float64 {
	k, m, n := float64(seeds), float64(block*blockBits), float64(elems)
	return math.Pow(1-math.Exp(-k*n/m), k)
}

type stringGenerator struct {
	r *rand.Rand
}

func newStringGenerator() *stringGenerator {
	return &stringGenerator{rand.New(rand.NewPCG(1, 2))}
}

func (g *stringGenerator) next() string {
	l := g.r.IntN(50) // length
	var runes []rune
	for range l {
		runes = append(runes, rune(' '+rand.IntN('~'-' ')))
	}
	return string(runes)
}

// TestDegenerateFilter checks that the degenerate filter with no elements
// results in no false positives.
func TestDegenerateFilter(t *testing.T) {
	f := NewFilter(nil)
	g := newStringGenerator()
	for range 100 {
		s := g.next()
		if f.MayContain(s) {
			t.Errorf("MayContain(%q) = true, want false", s)
		}
	}
}


================================================
FILE: gopls/internal/cache/analysis.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

// This file defines gopls' driver for modular static analysis (go/analysis).

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/gob"
	"encoding/json"
	"errors"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"log"
	urlpkg "net/url"
	"path/filepath"
	"reflect"
	"runtime"
	"runtime/debug"
	"slices"
	"sort"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/frob"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/persistent"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/analysis/driverutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/facts"
)

/*

   DESIGN

   An analysis request ([Snapshot.Analyze]) computes diagnostics for the
   requested packages using the set of analyzers enabled in this view. Each
   request constructs a transitively closed DAG of nodes, each representing a
   package, then works bottom up in parallel postorder calling
   [analysisNode.runCached] to ensure that each node's analysis summary is up
   to date. The summary contains the analysis diagnostics and serialized facts.

   The entire DAG is ephemeral. Each node in the DAG records the set of
   analyzers to run: the complete set for the root packages, and the "facty"
   subset for dependencies. Each package is thus analyzed at most once.

   Each node has a cryptographic key, which is either memoized in the Snapshot
   or computed by [analysisNode.cacheKey]. This key is a hash of the "recipe"
   for the analysis step, including the inputs into the type checked package
   (and its reachable dependencies), the set of analyzers, and importable
   facts.

   The key is sought in a machine-global persistent file-system based cache. If
   this gopls process, or another gopls process on the same machine, has
   already performed this analysis step, runCached will make a cache hit and
   load the serialized summary of the results. If not, it will have to proceed
   to run() to parse and type-check the package and then apply a set of
   analyzers to it. (The set of analyzers applied to a single package itself
   forms a graph of "actions", and it too is evaluated in parallel postorder;
   these dependency edges within the same package are called "horizontal".)
   Finally it writes a new cache entry containing serialized diagnostics and
   analysis facts.

   The summary must record whether a package is transitively error-free
   (whether it would compile) because many analyzers are not safe to run on
   packages with inconsistent types.

   For fact encoding, we use the same fact set as the unitchecker (vet) to
   record and serialize analysis facts. The fact serialization mechanism is
   analogous to "deep" export data.

*/

// TODO(adonovan):
// - Add a (white-box) test of pruning when a change doesn't affect export data.
// - Optimise pruning based on subset of packages mentioned in exportdata.
// - Better logging so that it is possible to deduce why an analyzer is not
//   being run--often due to very indirect failures. Even if the ultimate
//   consumer decides to ignore errors, tests and other situations want to be
//   assured of freedom from errors, not just missing results. This should be
//   recorded.

// AnalysisProgressTitle is the title of the progress report for ongoing
// analysis. It is sought by regression tests for the progress reporting
// feature.
const AnalysisProgressTitle = "Analyzing Dependencies"

// Analyze applies the set of enabled analyzers to the packages in the pkgs
// map, and returns their diagnostics.
//
// Notifications of progress may be sent to the optional reporter.
func (s *Snapshot) Analyze(ctx context.Context, pkgs map[PackageID]*metadata.Package, reporter *progress.Tracker) ([]*Diagnostic, error) {
	start := time.Now() // for progress reporting

	var tagStr string // sorted comma-separated list of PackageIDs
	{
		keys := make([]string, 0, len(pkgs))
		for id := range pkgs {
			keys = append(keys, string(id))
		}
		sort.Strings(keys)
		tagStr = strings.Join(keys, ",")
	}
	ctx, done := event.Start(ctx, "snapshot.Analyze", label.Package.Of(tagStr))
	defer done()

	// Filter and sort enabled root analyzers.
	// A disabled analyzer may still be run if required by another.
	var (
		toSrc            = make(map[*analysis.Analyzer]*settings.Analyzer)
		enabledAnalyzers []*analysis.Analyzer // enabled subset + transitive requirements
	)
	for _, a := range settings.AllAnalyzers {
		if a.Enabled(s.Options()) {
			toSrc[a.Analyzer()] = a
			enabledAnalyzers = append(enabledAnalyzers, a.Analyzer())
		}
	}
	sort.Slice(enabledAnalyzers, func(i, j int) bool {
		return enabledAnalyzers[i].Name < enabledAnalyzers[j].Name
	})

	enabledAnalyzers = requiredAnalyzers(enabledAnalyzers)

	// Perform basic sanity checks.
	// (Ideally we would do this only once.)
	if err := analysis.Validate(enabledAnalyzers); err != nil {
		return nil, fmt.Errorf("invalid analyzer configuration: %v", err)
	}

	stableNames := make(map[*analysis.Analyzer]string)

	var facty []*analysis.Analyzer // facty subset of enabled + transitive requirements
	for _, a := range enabledAnalyzers {
		// TODO(adonovan): reject duplicate stable names (very unlikely).
		stableNames[a] = stableName(a)

		// Register fact types of all required analyzers.
		if len(a.FactTypes) > 0 {
			facty = append(facty, a)
			for _, f := range a.FactTypes {
				gob.Register(f) // <2us
			}
		}
	}
	facty = requiredAnalyzers(facty)

	batch, release := s.acquireTypeChecking()
	defer release()

	ids := moremaps.KeySlice(pkgs)
	handles, err := s.getPackageHandles(ctx, ids)
	if err != nil {
		return nil, err
	}
	batch.addHandles(handles)

	// Starting from the root packages and following DepsByPkgPath,
	// build the DAG of packages we're going to analyze.
	//
	// Root nodes will run the enabled set of analyzers,
	// whereas dependencies will run only the facty set.
	// Because (by construction) enabled is a superset of facty,
	// we can analyze each node with exactly one set of analyzers.
	nodes := make(map[PackageID]*analysisNode)
	var leaves []*analysisNode // nodes with no unfinished successors
	var makeNode func(from *analysisNode, id PackageID) (*analysisNode, error)
	makeNode = func(from *analysisNode, id PackageID) (*analysisNode, error) {
		an, ok := nodes[id]
		if !ok {
			ph := handles[id]
			if ph == nil {
				return nil, bug.Errorf("no metadata for %s", id)
			}

			// -- preorder --

			an = &analysisNode{
				parseCache:  s.view.parseCache,
				fsource:     s, // expose only ReadFile
				batch:       batch,
				ph:          ph,
				analyzers:   facty, // all nodes run at least the facty analyzers
				stableNames: stableNames,
			}
			nodes[id] = an

			// -- recursion --

			// Build subgraphs for dependencies.
			an.succs = make(map[PackageID]*analysisNode, len(ph.mp.DepsByPkgPath))
			for _, depID := range ph.mp.DepsByPkgPath {
				dep, err := makeNode(an, depID)
				if err != nil {
					return nil, err
				}
				an.succs[depID] = dep
			}

			// -- postorder --

			// Add leaf nodes (no successors) directly to queue.
			if len(an.succs) == 0 {
				leaves = append(leaves, an)
			}
		}
		// Add edge from predecessor.
		if from != nil {
			from.unfinishedSuccs.Add(+1) // incref
			an.preds = append(an.preds, from)
		}
		// Increment unfinishedPreds even for root nodes (from==nil), so that their
		// Action summaries are never cleared.
		an.unfinishedPreds.Add(+1)
		return an, nil
	}

	// For root packages, we run the enabled set of analyzers.
	var roots []*analysisNode
	for id := range pkgs {
		root, err := makeNode(nil, id)
		if err != nil {
			return nil, err
		}
		root.analyzers = enabledAnalyzers
		roots = append(roots, root)
	}

	// Progress reporting. If supported, gopls reports progress on analysis
	// passes that are taking a long time.
	maybeReport := func(completed int64) {}

	// Enable progress reporting if enabled by the user
	// and we have a capable reporter.
	if reporter != nil && reporter.SupportsWorkDoneProgress() && s.Options().AnalysisProgressReporting {
		var reportAfter = s.Options().ReportAnalysisProgressAfter // tests may set this to 0
		const reportEvery = 1 * time.Second

		ctx, cancel := context.WithCancel(ctx)
		defer cancel()

		var (
			reportMu   sync.Mutex
			lastReport time.Time
			wd         *progress.WorkDone
		)
		defer func() {
			reportMu.Lock()
			defer reportMu.Unlock()

			if wd != nil {
				wd.End(ctx, "Done.") // ensure that the progress report exits
			}
		}()
		maybeReport = func(completed int64) {
			now := time.Now()
			if now.Sub(start) < reportAfter {
				return
			}

			reportMu.Lock()
			defer reportMu.Unlock()

			if wd == nil {
				wd = reporter.Start(ctx, AnalysisProgressTitle, "", nil, cancel)
			}

			if now.Sub(lastReport) > reportEvery {
				lastReport = now
				// Trailing space is intentional: some LSP clients strip newlines.
				msg := fmt.Sprintf(`Indexed %d/%d packages. (Set "analysisProgressReporting" to false to disable notifications.)`,
					completed, len(nodes))
				wd.Report(ctx, msg, float64(completed)/float64(len(nodes)))
			}
		}
	}

	// Execute phase: run leaves first, adding
	// new nodes to the queue as they become leaves.
	var g errgroup.Group

	// Analysis is CPU-bound.
	//
	// Note: avoid g.SetLimit here: it makes g.Go stop accepting work, which
	// prevents workers from enqeuing, and thus finishing, and thus allowing the
	// group to make progress: deadlock.
	limiter := make(chan unit, runtime.GOMAXPROCS(0))
	var completed atomic.Int64

	var enqueue func(*analysisNode)
	enqueue = func(an *analysisNode) {
		g.Go(func() error {
			limiter <- unit{}
			defer func() { <-limiter }()

			// Check to see if we already have a valid cache key. If not, compute it.
			//
			// The snapshot field that memoizes keys depends on whether this key is
			// for the analysis result including all enabled analyzer, or just facty analyzers.
			var keys *persistent.Map[PackageID, file.Hash]
			if _, root := pkgs[an.ph.mp.ID]; root {
				keys = s.fullAnalysisKeys
			} else {
				keys = s.factyAnalysisKeys
			}

			// As keys is referenced by a snapshot field, it's guarded by s.mu.
			s.mu.Lock()
			key, keyFound := keys.Get(an.ph.mp.ID)
			s.mu.Unlock()

			if !keyFound {
				key = an.cacheKey()
				s.mu.Lock()
				keys.Set(an.ph.mp.ID, key, nil)
				s.mu.Unlock()
			}

			summary, err := an.runCached(ctx, key)
			if err != nil {
				return err // cancelled, or failed to produce a package
			}

			maybeReport(completed.Add(1))
			an.summary = summary

			// Notify each waiting predecessor,
			// and enqueue it when it becomes a leaf.
			for _, pred := range an.preds {
				if pred.unfinishedSuccs.Add(-1) == 0 { // decref
					enqueue(pred)
				}
			}

			// Notify each successor that we no longer need
			// its action summaries, which hold Result values.
			// After the last one, delete it, so that we
			// free up large results such as SSA.
			for _, succ := range an.succs {
				succ.decrefPreds()
			}
			return nil
		})
	}
	for _, leaf := range leaves {
		enqueue(leaf)
	}
	if err := g.Wait(); err != nil {
		return nil, err // cancelled, or failed to produce a package
	}

	// Inv: all root nodes now have a summary (#66732).
	//
	// We know this is falsified empirically. This means either
	// the summary was "successfully" set to nil (above), or there
	// is a problem with the graph such the enqueuing leaves does
	// not lead to completion of roots (or an error).
	for _, root := range roots {
		if root.summary == nil {
			bug.Report("root analysisNode has nil summary")
		}
	}

	// Report diagnostics only from enabled actions that succeeded.
	// Errors from creating or analyzing packages are ignored.
	// Diagnostics are reported in the order of the analyzers argument.
	//
	// TODO(adonovan): ignoring action errors gives the caller no way
	// to distinguish "there are no problems in this code" from
	// "the code (or analyzers!) are so broken that we couldn't even
	// begin the analysis you asked for".
	// Even if current callers choose to discard the
	// results, we should propagate the per-action errors.
	var results []*Diagnostic
	for _, root := range roots {
		for _, a := range enabledAnalyzers {
			// Skip analyzers that were added only to
			// fulfil requirements of the original set.
			srcAnalyzer, ok := toSrc[a]
			if !ok {
				// Although this 'skip' operation is logically sound,
				// it is nonetheless surprising that its absence should
				// cause #60909 since none of the analyzers currently added for
				// requirements (e.g. ctrlflow, inspect, buildssa)
				// is capable of reporting diagnostics.
				if summary := root.summary.Actions[stableNames[a]]; summary != nil {
					if n := len(summary.Diagnostics); n > 0 {
						bug.Reportf("Internal error: got %d unexpected diagnostics from analyzer %s. This analyzer was added only to fulfil the requirements of the requested set of analyzers, and it is not expected that such analyzers report diagnostics. Please report this in issue #60909.", n, a)
					}
				}
				continue
			}

			// Inv: root.summary is the successful result of run (via runCached).
			// TODO(adonovan): fix: root.summary is sometimes nil! (#66732).
			summary, ok := root.summary.Actions[stableNames[a]]
			if summary == nil {
				panic(fmt.Sprintf("analyzeSummary.Actions[%q] = (nil, %t); got %v (#60551)",
					stableNames[a], ok, root.summary.Actions))
			}
			if summary.Err != "" {
				continue // action failed
			}
			for _, gobDiag := range summary.Diagnostics {
				results = append(results, toSourceDiagnostic(srcAnalyzer, &gobDiag))
			}
		}
	}
	return results, nil
}

func (an *analysisNode) decrefPreds() {
	if an.unfinishedPreds.Add(-1) == 0 {
		an.summary.Actions = nil
	}
}

// An analysisNode is a node in a doubly-linked DAG isomorphic to the
// import graph. Each node represents a single package, and the DAG
// represents a batch of analysis work done at once using a single
// realm of token.Pos or types.Object values.
//
// A complete DAG is created anew for each batch of analysis;
// subgraphs are not reused over time.
// TODO(rfindley): with cached keys we can typically avoid building the full
// DAG, so as an optimization we should rewrite this using a top-down
// traversal, rather than bottom-up.
//
// Each node's run method is called in parallel postorder. On success,
// its summary field is populated, either from the cache (hit), or by
// type-checking and analyzing syntax (miss).
type analysisNode struct {
	parseCache      *parseCache                 // shared parse cache
	fsource         file.Source                 // Snapshot.ReadFile, for use by Pass.ReadFile
	batch           *typeCheckBatch             // type checking batch, for shared type checking
	ph              *packageHandle              // package handle, for key and reachability analysis
	analyzers       []*analysis.Analyzer        // set of analyzers to run
	preds           []*analysisNode             // graph edges:
	succs           map[PackageID]*analysisNode //   (preds -> self -> succs)
	unfinishedSuccs atomic.Int32
	unfinishedPreds atomic.Int32                  // effectively a summary.Actions refcount
	summary         *analyzeSummary               // serializable result of analyzing this package
	stableNames     map[*analysis.Analyzer]string // cross-process stable names for Analyzers

	summaryHashOnce sync.Once
	_summaryHash    file.Hash // memoized hash of data affecting dependents
}

func (an *analysisNode) String() string { return string(an.ph.mp.ID) }

// summaryHash computes the hash of the node summary, which may affect other
// nodes depending on this node.
//
// The result is memoized to avoid redundant work when analyzing multiple
// dependents.
func (an *analysisNode) summaryHash() file.Hash {
	an.summaryHashOnce.Do(func() {
		hasher := sha256.New()
		fmt.Fprintf(hasher, "dep: %s\n", an.ph.mp.PkgPath)
		fmt.Fprintf(hasher, "compiles: %t\n", an.summary.Compiles)

		// action results: errors and facts
		for name, summary := range moremaps.Sorted(an.summary.Actions) {
			fmt.Fprintf(hasher, "action %s\n", name)
			if summary.Err != "" {
				fmt.Fprintf(hasher, "error %s\n", summary.Err)
			} else {
				fmt.Fprintf(hasher, "facts %s\n", summary.FactsHash)
				// We can safely omit summary.diagnostics
				// from the key since they have no downstream effect.
			}
		}
		hasher.Sum(an._summaryHash[:0])
	})
	return an._summaryHash
}

// analyzeSummary is a gob-serializable summary of successfully
// applying a list of analyzers to a package.
type analyzeSummary struct {
	Compiles bool      // transitively free of list/parse/type errors
	Actions  actionMap // maps analyzer stablename to analysis results (*actionSummary)
}

// actionMap defines a stable Gob encoding for a map.
// TODO(adonovan): generalize and move to a library when we can use generics.
type actionMap map[string]*actionSummary

var (
	_ gob.GobEncoder = (actionMap)(nil)
	_ gob.GobDecoder = (*actionMap)(nil)
)

type actionsMapEntry struct {
	K string
	V *actionSummary
}

func (m actionMap) GobEncode() ([]byte, error) {
	entries := make([]actionsMapEntry, 0, len(m))
	for k, v := range m {
		entries = append(entries, actionsMapEntry{k, v})
	}
	sort.Slice(entries, func(i, j int) bool {
		return entries[i].K < entries[j].K
	})
	var buf bytes.Buffer
	err := gob.NewEncoder(&buf).Encode(entries)
	return buf.Bytes(), err
}

func (m *actionMap) GobDecode(data []byte) error {
	var entries []actionsMapEntry
	if err := gob.NewDecoder(bytes.NewReader(data)).Decode(&entries); err != nil {
		return err
	}
	*m = make(actionMap, len(entries))
	for _, e := range entries {
		(*m)[e.K] = e.V
	}
	return nil
}

// actionSummary is a gob-serializable summary of one possibly failed analysis action.
// If Err is non-empty, the other fields are undefined.
type actionSummary struct {
	Facts       []byte    // the encoded facts.Set
	FactsHash   file.Hash // hash(Facts)
	Diagnostics []gobDiagnostic
	Err         string // "" => success
}

var (
	// inFlightAnalyses records active analysis operations so that later requests
	// can be satisfied by joining onto earlier requests that are still active.
	//
	// Note that persistent=false, so results are cleared once they are delivered
	// to awaiting goroutines.
	inFlightAnalyses = newFutureCache[file.Hash, *analyzeSummary](false)

	// cacheLimit reduces parallelism of filecache updates.
	// We allow more than typical GOMAXPROCS as it's a mix of CPU and I/O.
	cacheLimit = make(chan unit, 32)
)

// runCached applies a list of analyzers (plus any others
// transitively required by them) to a package.  It succeeds as long
// as it could produce a types.Package, even if there were direct or
// indirect list/parse/type errors, and even if all the analysis
// actions failed. It usually fails only if the package was unknown,
// a file was missing, or the operation was cancelled.
//
// The provided key is the cache key for this package.
func (an *analysisNode) runCached(ctx context.Context, key file.Hash) (*analyzeSummary, error) {
	// At this point we have the action results (serialized packages and facts)
	// of our immediate dependencies, and the metadata and content of this
	// package.
	//
	// We now consult a global cache of promised results. If nothing material has
	// changed, we'll make a hit in the shared cache.

	// Access the cache.
	var summary *analyzeSummary
	const cacheKind = "analysis"
	if data, err := filecache.Get(cacheKind, key); err == nil {
		// cache hit
		analyzeSummaryCodec.Decode(data, &summary)
		if summary == nil { // debugging #66732
			bug.Reportf("analyzeSummaryCodec.Decode yielded nil *analyzeSummary")
		}
	} else if err != filecache.ErrNotFound {
		return nil, bug.Errorf("internal error reading shared cache: %v", err)
	} else {
		// Cache miss: do the work.
		cachedSummary, err := inFlightAnalyses.get(ctx, key, func(ctx context.Context) (*analyzeSummary, error) {
			summary, err := an.run(ctx)
			if err != nil {
				return nil, err
			}
			if summary == nil { // debugging #66732 (can't happen)
				bug.Reportf("analyzeNode.run returned nil *analyzeSummary")
			}
			go func() {
				cacheLimit <- unit{}            // acquire token
				defer func() { <-cacheLimit }() // release token

				data := analyzeSummaryCodec.Encode(summary)
				if false {
					log.Printf("Set key=%d value=%d id=%s\n", len(key), len(data), an.ph.mp.ID)
				}
				if err := filecache.Set(cacheKind, key, data); err != nil {
					event.Error(ctx, "internal error updating analysis shared cache", err)
				}
			}()
			return summary, nil
		})
		if err != nil {
			return nil, err
		}

		// Copy the computed summary. In decrefPreds, we may zero out
		// summary.actions, but can't mutate a shared result.
		copy := *cachedSummary
		summary = &copy
	}

	return summary, nil
}

// cacheKey returns a cache key that is a cryptographic digest
// of the all the values that might affect type checking and analysis:
// the analyzer names, package metadata, names and contents of
// compiled Go files, and vdeps (successor) information
// (export data and facts).
func (an *analysisNode) cacheKey() file.Hash {
	hasher := sha256.New()

	// In principle, a key must be the hash of an
	// unambiguous encoding of all the relevant data.
	// If it's ambiguous, we risk collisions.

	// analyzers
	fmt.Fprintf(hasher, "analyzers: %d\n", len(an.analyzers))
	for _, a := range an.analyzers {
		fmt.Fprintln(hasher, a.Name)
	}

	// type checked package
	fmt.Fprintf(hasher, "package: %s\n", an.ph.key)

	// metadata errors: used for 'compiles' field
	fmt.Fprintf(hasher, "errors: %d", len(an.ph.mp.Errors))

	// vdeps, in PackageID order
	for _, vdep := range moremaps.Sorted(an.succs) {
		hash := vdep.summaryHash()
		hasher.Write(hash[:])
	}

	var hash file.Hash
	hasher.Sum(hash[:0])
	return hash
}

// run implements the cache-miss case.
// This function does not access the snapshot.
//
// Postcondition: on success, the analyzeSummary.Actions
// key set is {a.Name for a in analyzers}.
func (an *analysisNode) run(ctx context.Context) (*analyzeSummary, error) {
	// Type-check the package syntax.
	pkg, err := an.typeCheck(ctx)
	if err != nil {
		return nil, err
	}

	// Poll cancellation state.
	if err := ctx.Err(); err != nil {
		return nil, err
	}

	// -- analysis --

	// Build action graph for this package.
	// Each graph node (action) is one unit of analysis.
	actions := make(map[*analysis.Analyzer]*action)
	var mkAction func(a *analysis.Analyzer) *action
	mkAction = func(a *analysis.Analyzer) *action {
		act, ok := actions[a]
		if !ok {
			var hdeps []*action
			for _, req := range a.Requires {
				hdeps = append(hdeps, mkAction(req))
			}
			act = &action{
				a:          a,
				fsource:    an.fsource,
				stableName: an.stableNames[a],
				pkg:        pkg,
				vdeps:      an.succs,
				hdeps:      hdeps,
			}
			actions[a] = act
		}
		return act
	}

	// Build actions for initial package.
	var roots []*action
	for _, a := range an.analyzers {
		roots = append(roots, mkAction(a))
	}

	// Execute the graph in parallel.
	execActions(ctx, roots)
	// Inv: each root's summary is set (whether success or error).

	// Don't return (or cache) the result in case of cancellation.
	if err := ctx.Err(); err != nil {
		return nil, err // cancelled
	}

	// Return summaries only for the requested actions.
	summaries := make(map[string]*actionSummary)
	for _, root := range roots {
		if root.summary == nil {
			panic("root has nil action.summary (#60551)")
		}
		summaries[root.stableName] = root.summary
	}

	return &analyzeSummary{
		Compiles: pkg.compiles,
		Actions:  summaries,
	}, nil
}

func (an *analysisNode) typeCheck(ctx context.Context) (*analysisPackage, error) {
	ppkg, err := an.batch.getPackage(ctx, an.ph)
	if err != nil {
		return nil, err
	}

	compiles := len(an.ph.mp.Errors) == 0 && len(ppkg.TypeErrors()) == 0

	// The go/analysis framework implicitly promises to deliver
	// trees with legacy ast.Object resolution. Do that now.
	files := make([]*ast.File, len(ppkg.CompiledGoFiles()))
	for i, p := range ppkg.CompiledGoFiles() {
		p.Resolve()
		files[i] = p.File
		if p.ParseErr != nil {
			compiles = false // parse error
		}
	}

	// The fact decoder needs a means to look up a Package by path.
	pkgLookup := typesLookup(ppkg.Types())
	factsDecoder := facts.NewDecoderFunc(ppkg.Types(), func(path string) *types.Package {
		// Note: Decode is called concurrently, and thus so is this function.

		// Does the fact relate to a package reachable through imports?
		if !an.ph.reachable.MayContain(path) {
			return nil
		}

		return pkgLookup(path)
	})

	var typeErrors []types.Error
filterErrors:
	for _, typeError := range ppkg.TypeErrors() {
		// Suppress type errors in files with parse errors
		// as parser recovery can be quite lossy (#59888).
		for _, p := range ppkg.CompiledGoFiles() {
			if p.ParseErr != nil && astutil.NodeContainsPos(p.File, typeError.Pos) {
				continue filterErrors
			}
		}
		typeErrors = append(typeErrors, typeError)
	}

	for _, vdep := range an.succs {
		if !vdep.summary.Compiles {
			compiles = false // transitive error
		}
	}

	return &analysisPackage{
		pkg:          ppkg,
		files:        files,
		typeErrors:   typeErrors,
		compiles:     compiles,
		factsDecoder: factsDecoder,
	}, nil
}

// typesLookup implements a concurrency safe depth-first traversal searching
// imports of pkg for a given package path.
func typesLookup(pkg *types.Package) func(string) *types.Package {
	var (
		mu sync.Mutex // guards impMap and pending

		// impMap memoizes the lookup of package paths.
		impMap = map[string]*types.Package{
			pkg.Path(): pkg,
		}
		// pending is a FIFO queue of packages that have yet to have their
		// dependencies fully scanned.
		// Invariant: all entries in pending are already mapped in impMap.
		pending = []*types.Package{pkg}
	)

	// search scans children the next package in pending, looking for pkgPath.
	search := func(pkgPath string) (sought *types.Package, numPending int) {
		mu.Lock()
		defer mu.Unlock()

		if p, ok := impMap[pkgPath]; ok {
			return p, len(pending)
		}

		if len(pending) == 0 {
			return nil, 0
		}

		pkg := pending[0]
		pending = pending[1:]
		for _, dep := range pkg.Imports() {
			depPath := dep.Path()
			if _, ok := impMap[depPath]; ok {
				continue
			}
			impMap[depPath] = dep

			pending = append(pending, dep)
			if depPath == pkgPath {
				// Don't return early; finish processing pkg's deps.
				sought = dep
			}
		}
		return sought, len(pending)
	}

	return func(pkgPath string) *types.Package {
		p, np := (*types.Package)(nil), 1
		for p == nil && np > 0 {
			p, np = search(pkgPath)
		}
		return p
	}
}

// analysisPackage contains information about a package, including
// syntax trees, used transiently during its type-checking and analysis.
type analysisPackage struct {
	pkg          *Package
	files        []*ast.File   // same as parsed[i].File
	typeErrors   []types.Error // filtered type checker errors
	compiles     bool          // package is transitively free of list/parse/type errors
	factsDecoder *facts.Decoder
}

// An action represents one unit of analysis work: the application of
// one analysis to one package. Actions form a DAG, both within a
// package (as different analyzers are applied, either in sequence or
// parallel), and across packages (as dependencies are analyzed).
type action struct {
	once       sync.Once
	a          *analysis.Analyzer
	fsource    file.Source // Snapshot.ReadFile, for Pass.ReadFile
	stableName string      // cross-process stable name of analyzer
	pkg        *analysisPackage
	hdeps      []*action                   // horizontal dependencies
	vdeps      map[PackageID]*analysisNode // vertical dependencies

	// results of action.exec():
	result  any // result of Run function, of type a.ResultType
	summary *actionSummary
	err     error
}

func (act *action) String() string {
	return fmt.Sprintf("%s@%s", act.a.Name, act.pkg.pkg.metadata.ID)
}

// execActions executes a set of action graph nodes in parallel.
// Postcondition: each action.summary is set, even in case of error.
func execActions(ctx context.Context, actions []*action) {
	var wg sync.WaitGroup
	for _, act := range actions {
		wg.Go(func() {
			act.once.Do(func() {
				execActions(ctx, act.hdeps) // analyze "horizontal" dependencies
				act.result, act.summary, act.err = act.exec(ctx)
				if act.err != nil {
					act.summary = &actionSummary{Err: act.err.Error()}
					// TODO(adonovan): suppress logging. But
					// shouldn't the root error's causal chain
					// include this information?
					if false { // debugging
						log.Printf("act.exec(%v) failed: %v", act, act.err)
					}
				}
			})
			if act.summary == nil {
				panic("nil action.summary (#60551)")
			}
		})
	}
	wg.Wait()
}

// exec defines the execution of a single action.
// It returns the (ephemeral) result of the analyzer's Run function,
// along with its (serializable) facts and diagnostics.
// Or it returns an error if the analyzer did not run to
// completion and deliver a valid result.
func (act *action) exec(ctx context.Context) (any, *actionSummary, error) {
	analyzer := act.a
	apkg := act.pkg

	hasFacts := len(analyzer.FactTypes) > 0

	// Report an error if any action dependency (vertical or horizontal) failed.
	// To avoid long error messages describing chains of failure,
	// we return the dependencies' error' unadorned.
	if hasFacts {
		// TODO(adonovan): use deterministic order.
		for _, vdep := range act.vdeps {
			if summ := vdep.summary.Actions[act.stableName]; summ.Err != "" {
				return nil, nil, errors.New(summ.Err)
			}
		}
	}
	for _, dep := range act.hdeps {
		if dep.err != nil {
			return nil, nil, dep.err
		}
	}
	// Inv: all action dependencies succeeded.

	// Were there list/parse/type errors that might prevent analysis?
	if !apkg.compiles && !analyzer.RunDespiteErrors {
		return nil, nil, fmt.Errorf("skipping analysis %q because package %q does not compile", analyzer.Name, apkg.pkg.metadata.ID)
	}
	// Inv: package is well-formed enough to proceed with analysis.

	if false { // debugging
		log.Println("action.exec", act)
	}

	// Gather analysis Result values from horizontal dependencies.
	inputs := make(map[*analysis.Analyzer]any)
	for _, dep := range act.hdeps {
		inputs[dep.a] = dep.result
	}

	// TODO(adonovan): opt: facts.Set works but it may be more
	// efficient to fork and tailor it to our precise needs.
	//
	// We've already sharded the fact encoding by action
	// so that it can be done in parallel.
	// We could eliminate locking.
	// We could also dovetail more closely with the export data
	// decoder to obtain a more compact representation of
	// packages and objects (e.g. its internal IDs, instead
	// of PkgPaths and objectpaths.)
	// More importantly, we should avoid re-export of
	// facts that related to objects that are discarded
	// by "deep" export data. Better still, use a "shallow" approach.

	// Read and decode analysis facts for each direct import.
	factset, err := apkg.factsDecoder.Decode(func(pkgPath string) ([]byte, error) {
		if !hasFacts {
			return nil, nil // analyzer doesn't use facts, so no vdeps
		}

		// Package.Imports() may contain a fake "C" package. Ignore it.
		if pkgPath == "C" {
			return nil, nil
		}

		id, ok := apkg.pkg.metadata.DepsByPkgPath[PackagePath(pkgPath)]
		if !ok {
			// This may mean imp was synthesized by the type
			// checker because it failed to import it for any reason
			// (e.g. bug processing export data; metadata ignoring
			// a cycle-forming import).
			// In that case, the fake package's imp.Path
			// is set to the failed importPath (and thus
			// it may lack a "vendor/" prefix).
			//
			// For now, silently ignore it on the assumption
			// that the error is already reported elsewhere.
			// return nil, fmt.Errorf("missing metadata")
			return nil, nil
		}

		vdep := act.vdeps[id]
		if vdep == nil {
			return nil, bug.Errorf("internal error in %s: missing vdep for id=%s", apkg.pkg.Types().Path(), id)
		}

		return vdep.summary.Actions[act.stableName].Facts, nil
	})
	if err != nil {
		return nil, nil, fmt.Errorf("internal error decoding analysis facts: %w", err)
	}

	// TODO(adonovan): make Export*Fact panic rather than discarding
	// undeclared fact types, so that we discover bugs in analyzers.
	factFilter := make(map[reflect.Type]bool)
	for _, f := range analyzer.FactTypes {
		factFilter[reflect.TypeOf(f)] = true
	}

	// Now run the (pkg, analyzer) action.
	var diagnostics []gobDiagnostic

	pass := &analysis.Pass{
		Analyzer:     analyzer,
		Fset:         apkg.pkg.FileSet(),
		Files:        apkg.files,
		OtherFiles:   nil, // since gopls doesn't handle non-Go (e.g. asm) files
		IgnoredFiles: nil, // zero-config gopls should analyze these files in another view
		Pkg:          apkg.pkg.Types(),
		TypesInfo:    apkg.pkg.TypesInfo(),
		TypesSizes:   apkg.pkg.TypesSizes(),
		TypeErrors:   apkg.typeErrors,
		ResultOf:     inputs,
		Report: func(d analysis.Diagnostic) {
			// Assert that SuggestedFixes are well formed.
			//
			// ValidateFixes allows a fix.End to be slightly beyond
			// EOF to avoid spurious assertions when reporting
			// fixes as the end of truncated files; see #71659.
			if err := driverutil.ValidateFixes(apkg.pkg.FileSet(), analyzer, d.SuggestedFixes); err != nil {
				bug.Reportf("invalid SuggestedFixes: %v", err)
				d.SuggestedFixes = nil
			}
			diagnostic, err := toGobDiagnostic(apkg.pkg, analyzer, d)
			if err != nil {
				// Don't bug.Report here: these errors all originate in
				// posToLocation, and we can more accurately discriminate
				// severe errors from benign ones in that function.
				event.Error(ctx, fmt.Sprintf("internal error converting diagnostic from analyzer %q", analyzer.Name), err)
				return
			}
			diagnostics = append(diagnostics, diagnostic)
		},
		ImportObjectFact:  factset.ImportObjectFact,
		ExportObjectFact:  factset.ExportObjectFact,
		ImportPackageFact: factset.ImportPackageFact,
		ExportPackageFact: factset.ExportPackageFact,
		AllObjectFacts:    func() []analysis.ObjectFact { return factset.AllObjectFacts(factFilter) },
		AllPackageFacts:   func() []analysis.PackageFact { return factset.AllPackageFacts(factFilter) },
	}

	pass.ReadFile = func(filename string) ([]byte, error) {
		// Read file from snapshot, to ensure reads are consistent.
		//
		// TODO(adonovan): make the dependency analysis sound by
		// incorporating these additional files into the analysis
		// hash. This requires either (a) preemptively reading and
		// hashing a potentially large number of mostly irrelevant
		// files; or (b) some kind of dynamic dependency discovery
		// system like used in Bazel for C++ headers. Neither entices.
		if err := driverutil.CheckReadable(pass, filename); err != nil {
			return nil, err
		}
		h, err := act.fsource.ReadFile(ctx, protocol.URIFromPath(filename))
		if err != nil {
			return nil, err
		}
		content, err := h.Content()
		if err != nil {
			return nil, err // file doesn't exist
		}
		return slices.Clone(content), nil // follow ownership of os.ReadFile
	}

	// Recover from panics (only) within the analyzer logic.
	// (Use an anonymous function to limit the recover scope.)
	var result any
	func() {
		start := time.Now()
		defer func() {
			if r := recover(); r != nil {
				// An Analyzer panicked, likely due to a bug.
				//
				// In general we want to discover and fix such panics quickly,
				// so we don't suppress them, but some bugs in third-party
				// analyzers cannot be quickly fixed, so we use an allowlist
				// to suppress panics.
				const strict = true
				if strict && bug.PanicOnBugs &&
					analyzer.Name != "buildir" { // see https://github.com/dominikh/go-tools/issues/1343
					// Uncomment this when debugging suspected failures
					// in the driver, not the analyzer.
					if false {
						debug.SetTraceback("all") // show all goroutines
					}
					panic(r)
				} else {
					// In production, suppress the panic and press on.
					err = fmt.Errorf("analysis %s for package %s panicked: %v", analyzer.Name, pass.Pkg.Path(), r)
				}
			}

			// Accumulate running time for each checker.
			analyzerRunTimesMu.Lock()
			analyzerRunTimes[analyzer] += time.Since(start)
			analyzerRunTimesMu.Unlock()
		}()

		result, err = pass.Analyzer.Run(pass)
	}()
	if err != nil {
		return nil, nil, err
	}

	if got, want := reflect.TypeOf(result), pass.Analyzer.ResultType; got != want {
		return nil, nil, bug.Errorf(
			"internal error: on package %s, analyzer %s returned a result of type %v, but declared ResultType %v",
			pass.Pkg.Path(), pass.Analyzer, got, want)
	}

	// Disallow Export*Fact calls after Run.
	// (A panic means the Analyzer is abusing concurrency.)
	pass.ExportObjectFact = func(obj types.Object, fact analysis.Fact) {
		panic(fmt.Sprintf("%v: Pass.ExportObjectFact(%s, %T) called after Run", act, obj, fact))
	}
	pass.ExportPackageFact = func(fact analysis.Fact) {
		panic(fmt.Sprintf("%v: Pass.ExportPackageFact(%T) called after Run", act, fact))
	}

	factsdata := factset.Encode()
	return result, &actionSummary{
		Diagnostics: diagnostics,
		Facts:       factsdata,
		FactsHash:   file.HashOf(factsdata),
	}, nil
}

var (
	analyzerRunTimesMu sync.Mutex
	analyzerRunTimes   = make(map[*analysis.Analyzer]time.Duration)
)

type LabelDuration struct {
	Label    string
	Duration time.Duration
}

// AnalyzerRunTimes returns the accumulated time spent in each Analyzer's
// Run function since process start, in descending order.
func AnalyzerRunTimes() []LabelDuration {
	analyzerRunTimesMu.Lock()
	defer analyzerRunTimesMu.Unlock()

	slice := make([]LabelDuration, 0, len(analyzerRunTimes))
	for a, t := range analyzerRunTimes {
		slice = append(slice, LabelDuration{Label: a.Name, Duration: t})
	}
	sort.Slice(slice, func(i, j int) bool {
		return slice[i].Duration > slice[j].Duration
	})
	return slice
}

// requiredAnalyzers returns the transitive closure of required analyzers in preorder.
func requiredAnalyzers(analyzers []*analysis.Analyzer) []*analysis.Analyzer {
	var result []*analysis.Analyzer
	seen := make(map[*analysis.Analyzer]bool)
	var visitAll func([]*analysis.Analyzer)
	visitAll = func(analyzers []*analysis.Analyzer) {
		for _, a := range analyzers {
			if !seen[a] {
				seen[a] = true
				result = append(result, a)
				visitAll(a.Requires)
			}
		}
	}
	visitAll(analyzers)
	return result
}

var analyzeSummaryCodec = frob.CodecFor[*analyzeSummary]()

// -- data types for serialization of analysis.Diagnostic and golang.Diagnostic --

// (The name says gob but we use frob.)
var diagnosticsCodec = frob.CodecFor[[]gobDiagnostic]()

type gobDiagnostic struct {
	Location       protocol.Location
	Severity       protocol.DiagnosticSeverity
	Code           string
	CodeHref       string
	Source         string
	Message        string
	SuggestedFixes []gobSuggestedFix
	Related        []gobRelatedInformation
	Tags           []protocol.DiagnosticTag
}

type gobRelatedInformation struct {
	Location protocol.Location
	Message  string
}

type gobSuggestedFix struct {
	Message    string
	TextEdits  []gobTextEdit
	Command    *gobCommand
	ActionKind protocol.CodeActionKind
}

type gobCommand struct {
	Title     string
	Command   string
	Arguments []json.RawMessage
}

type gobTextEdit struct {
	Location protocol.Location
	NewText  []byte
}

// toGobDiagnostic converts an analysis.Diagnosic to a serializable gobDiagnostic,
// which requires expanding token.Pos positions into protocol.Location form.
func toGobDiagnostic(pkg *Package, a *analysis.Analyzer, diag analysis.Diagnostic) (gobDiagnostic, error) {
	var fixes []gobSuggestedFix
	for _, fix := range diag.SuggestedFixes {
		var gobEdits []gobTextEdit
		for _, textEdit := range fix.TextEdits {
			loc, err := diagnosticPosToLocation(pkg, false, textEdit.Pos, textEdit.End)
			if err != nil {
				return gobDiagnostic{}, fmt.Errorf("in SuggestedFixes: %w", err)
			}
			gobEdits = append(gobEdits, gobTextEdit{
				Location: loc,
				NewText:  textEdit.NewText,
			})
		}
		fixes = append(fixes, gobSuggestedFix{
			Message:   fix.Message,
			TextEdits: gobEdits,
		})
	}

	var related []gobRelatedInformation
	for _, r := range diag.Related {
		// The position of RelatedInformation may be
		// within another (dependency) package.
		const allowDeps = true
		loc, err := diagnosticPosToLocation(pkg, allowDeps, r.Pos, r.End)
		if err != nil {
			return gobDiagnostic{}, fmt.Errorf("in Related: %w", err)
		}
		related = append(related, gobRelatedInformation{
			Location: loc,
			Message:  r.Message,
		})
	}

	loc, err := diagnosticPosToLocation(pkg, false, diag.Pos, diag.End)
	if err != nil {
		return gobDiagnostic{}, err
	}

	// The Code column of VSCode's Problems table renders this
	// information as "Source(Code)" where code is a link to CodeHref.
	// (The code field must be nonempty for anything to appear.)
	diagURL := effectiveURL(a, diag)
	code := "default"
	if diag.Category != "" {
		code = diag.Category
	}

	return gobDiagnostic{
		Location: loc,
		// Severity for analysis diagnostics is dynamic,
		// based on user configuration per analyzer.
		Code:           code,
		CodeHref:       diagURL,
		Source:         a.Name,
		Message:        diag.Message,
		SuggestedFixes: fixes,
		Related:        related,
		// Analysis diagnostics do not contain tags.
	}, nil
}

// diagnosticPosToLocation converts from token.Pos to protocol form, in the
// context of the specified package and, optionally, its dependencies.
func diagnosticPosToLocation(pkg *Package, allowDeps bool, start, end token.Pos) (protocol.Location, error) {
	if end == token.NoPos {
		end = start
	}

	fset := pkg.FileSet()
	tokFile := fset.File(start)

	// Find existing mapper by file name.
	// (Don't require an exact token.File match
	// as the analyzer may have re-parsed the file.)
	var (
		mapper *protocol.Mapper
		fixed  bool
	)
	for _, p := range pkg.CompiledGoFiles() {
		if p.Tok.Name() == tokFile.Name() {
			mapper = p.Mapper
			fixed = p.Fixed() // suppress some assertions after parser recovery
			break
		}
	}
	// TODO(adonovan): search pkg.AsmFiles too; see #71754.
	if mapper != nil {
		// debugging #64547
		fileStart := token.Pos(tokFile.Base())
		fileEnd := fileStart + token.Pos(tokFile.Size())
		if start < fileStart {
			if !fixed {
				bug.Reportf("start < start of file")
			}
			start = fileStart
		}
		if end < start {
			// This can happen if End is zero (#66683)
			// or a small positive displacement from zero
			// due to recursive Node.End() computation.
			// This usually arises from poor parser recovery
			// of an incomplete term at EOF.
			if !fixed {
				bug.Reportf("end < start of file")
			}
			end = fileEnd
		}
		if end > fileEnd+1 {
			if !fixed {
				bug.Reportf("end > end of file + 1")
			}
			end = fileEnd
		}

		return mapper.PosLocation(tokFile, start, end)
	}

	// Inv: the positions are not within this package.

	if allowDeps {
		// Positions in Diagnostic.RelatedInformation may belong to a
		// dependency package. We cannot accurately map them to
		// protocol.Location coordinates without a Mapper for the
		// relevant file, but none exists if the file was loaded from
		// export data, and we have no means (Snapshot) of loading it.
		//
		// So, fall back to approximate conversion to UTF-16:
		// for non-ASCII text, the column numbers may be wrong.
		var (
			startPosn = safetoken.StartPosition(fset, start)
			endPosn   = safetoken.EndPosition(fset, end)
		)
		return protocol.Location{
			URI: protocol.URIFromPath(startPosn.Filename),
			Range: protocol.Range{
				Start: protocol.Position{
					Line:      uint32(startPosn.Line - 1),
					Character: uint32(startPosn.Column - 1),
				},
				End: protocol.Position{
					Line:      uint32(endPosn.Line - 1),
					Character: uint32(endPosn.Column - 1),
				},
			},
		}, nil
	}

	// The start position was not among the package's parsed
	// Go files, indicating that the analyzer added new files
	// to the FileSet.
	//
	// For example, the cgocall analyzer re-parses and
	// type-checks some of the files in a special environment;
	// and asmdecl and other low-level runtime analyzers call
	// ReadFile to parse non-Go files.
	// (This is a supported feature, documented at go/analysis.)
	//
	// In principle these files could be:
	//
	// - OtherFiles (non-Go files such as asm).
	//   However, we set Pass.OtherFiles=[] because
	//   gopls won't service "diagnose" requests
	//   for non-Go files, so there's no point
	//   reporting diagnostics in them.
	//
	// - IgnoredFiles (files tagged for other configs).
	//   However, we set Pass.IgnoredFiles=[] because,
	//   in most cases, zero-config gopls should create
	//   another view that covers these files.
	//
	// - Referents of //line directives, as in cgo packages.
	//   The file names in this case are not known a priori.
	//   gopls generally tries to avoid honoring line directives,
	//   but analyzers such as cgocall may honor them.
	//
	// In short, it's unclear how this can be reached
	// other than due to an analyzer bug.

	return protocol.Location{}, bug.Errorf("diagnostic location is not among files of package: %s", tokFile.Name())
}

// effectiveURL computes the effective URL of diag,
// using the algorithm specified at Diagnostic.URL.
func effectiveURL(a *analysis.Analyzer, diag analysis.Diagnostic) string {
	u := diag.URL
	if u == "" && diag.Category != "" {
		u = "#" + diag.Category
	}
	if base, err := urlpkg.Parse(a.URL); err == nil {
		if rel, err := urlpkg.Parse(u); err == nil {
			u = base.ResolveReference(rel).String()
		}
	}
	return u
}

// stableName returns a name for the analyzer that is unique and
// stable across address spaces.
//
// Analyzer names are not unique. For example, gopls includes
// both x/tools/passes/nilness and staticcheck/nilness.
// For serialization, we must assign each analyzer a unique identifier
// that two gopls processes accessing the cache can agree on.
func stableName(a *analysis.Analyzer) string {
	// Incorporate the file and line of the analyzer's Run function.
	addr := reflect.ValueOf(a.Run).Pointer()
	fn := runtime.FuncForPC(addr)
	file, line := fn.FileLine(addr)

	// It is tempting to use just a.Name as the stable name when
	// it is unique, but making them always differ helps avoid
	// name/stablename confusion.
	return fmt.Sprintf("%s(%s:%d)", a.Name, filepath.Base(file), line)
}


================================================
FILE: gopls/internal/cache/cache.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"reflect"
	"strconv"
	"sync/atomic"

	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/internal/imports"
)

// ballast is a 100MB unused byte slice that exists only to reduce garbage
// collector CPU in small workspaces and at startup.
//
// The redesign of gopls described at https://go.dev/blog/gopls-scalability
// moved gopls to a model where it has a significantly smaller heap, yet still
// allocates many short-lived data structures during parsing and type checking.
// As a result, for some workspaces, particularly when opening a low-level
// package, the steady-state heap may be a small fraction of total allocation
// while rechecking the workspace, paradoxically causing the GC to consume much
// more CPU. For example, in one benchmark that analyzes the starlark
// repository, the steady-state heap was ~10MB, and the process of diagnosing
// the workspace allocated 100-200MB.
//
// The reason for this paradoxical behavior is that GC pacing
// (https://tip.golang.org/doc/gc-guide#GOGC) causes the collector to trigger
// at some multiple of the steady-state heap size, so a small steady-state heap
// causes GC to trigger sooner and more often when allocating the ephemeral
// structures.
//
// Allocating a 100MB ballast avoids this problem by ensuring a minimum heap
// size. The value of 100MB was chosen to be proportional to the in-memory
// cache in front the filecache package, and the throughput of type checking.
// Gopls already requires hundreds of megabytes of RAM to function.
//
// Note that while other use cases for a ballast were made obsolete by
// GOMEMLIMIT, ours is not. GOMEMLIMIT helps in cases where you have a
// containerized service and want to optimize its latency and throughput by
// taking advantage of available memory. However, in our case gopls is running
// on the developer's machine alongside other applications, and can have a wide
// range of memory footprints depending on the size of the user's workspace.
// Setting GOMEMLIMIT to too low a number would make gopls perform poorly on
// large repositories, and setting it to too high a number would make gopls a
// badly behaved tenant. Short of calibrating GOMEMLIMIT based on the user's
// workspace (an intractible problem), there is no way for gopls to use
// GOMEMLIMIT to solve its GC CPU problem.
//
// Because this allocation is large and occurs early, there is a good chance
// that rather than being recycled, it comes directly from the OS already
// zeroed, and since it is never accessed, the memory region may avoid being
// backed by pages of RAM. But see
// https://groups.google.com/g/golang-nuts/c/66d0cItfkjY/m/3NvgzL_sAgAJ
//
// For more details on this technique, see:
// https://blog.twitch.tv/en/2019/04/10/go-memory-ballast-how-i-learnt-to-stop-worrying-and-love-the-heap/
var ballast = make([]byte, 100*1e6)

// New Creates a new cache for gopls operation results, using the given file
// set, shared store, and session options.
//
// Both the fset and store may be nil, but if store is non-nil so must be fset
// (and they must always be used together), otherwise it may be possible to get
// cached data referencing token.Pos values not mapped by the FileSet.
func New(store *memoize.Store) *Cache {
	index := atomic.AddInt64(&cacheIndex, 1)

	if store == nil {
		store = &memoize.Store{}
	}

	c := &Cache{
		id:         strconv.FormatInt(index, 10),
		store:      store,
		memoizedFS: newMemoizedFS(),
		modCache: &sharedModCache{
			caches: make(map[string]*imports.DirInfoCache),
			timers: make(map[string]*refreshTimer),
		},
	}
	return c
}

// A Cache holds content that is shared across multiple gopls sessions.
type Cache struct {
	id string

	// store holds cached calculations.
	//
	// TODO(rfindley): at this point, these are not important, as we've moved our
	// content-addressable cache to the file system (the filecache package). It
	// is unlikely that this shared cache provides any shared value. We should
	// consider removing it, replacing current uses with a simpler futures cache,
	// as we've done for e.g. type-checked packages.
	store *memoize.Store

	// memoizedFS holds a shared file.Source that caches reads.
	//
	// Reads are invalidated when *any* session gets a didChangeWatchedFile
	// notification. This is fine: it is the responsibility of memoizedFS to hold
	// our best knowledge of the current file system state.
	*memoizedFS

	// modCache holds the shared goimports state for GOMODCACHE directories
	modCache *sharedModCache
}

var cacheIndex, sessionIndex, viewIndex int64

func (c *Cache) ID() string                     { return c.id }
func (c *Cache) MemStats() map[reflect.Type]int { return c.store.Stats() }

// FileStats returns information about the set of files stored in the cache.
// It is intended for debugging only.
func (c *Cache) FileStats() (stats command.FileStats) {
	stats.Total, stats.Largest, stats.Errs = c.fileStats()
	return
}


================================================
FILE: gopls/internal/cache/check.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"context"
	"crypto/sha256"
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/scanner"
	"go/token"
	"go/types"
	"regexp"
	"runtime"
	"sort"
	"strings"
	"sync"
	"sync/atomic"

	"golang.org/x/mod/module"
	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/bloom"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gcimporter"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

type unit = struct{}

// A typeCheckBatch holds data for a logical type-checking operation, which may
// type check many unrelated packages.
//
// It shares state such as parsed files and imports, to optimize type-checking
// for packages with overlapping dependency graphs.
type typeCheckBatch struct {
	// handleMu guards _handles, which must only be accessed via addHandles or
	// getHandle.
	//
	// An alternative would be to simply verify that package handles are present
	// on the Snapshot, and access them directly, rather than copying maps for
	// each caller. However, handles are accessed very frequently during type
	// checking, and ordinary go maps are measurably faster than the
	// persistent.Map used to store handles on the snapshot.
	handleMu sync.Mutex
	_handles map[PackageID]*packageHandle

	parseCache       *parseCache
	fset             *token.FileSet                          // describes all parsed or imported files
	cpulimit         chan unit                               // concurrency limiter for CPU-bound operations
	syntaxPackages   *futureCache[PackageID, *Package]       // transient cache of in-progress syntax futures
	importPackages   *futureCache[PackageID, *types.Package] // persistent cache of imports
	gopackagesdriver bool                                    // for bug reporting: were packages loaded with a driver?
}

// addHandles is called by each goroutine joining the type check batch, to
// ensure that the batch has all inputs necessary for type checking.
func (b *typeCheckBatch) addHandles(handles map[PackageID]*packageHandle) {
	b.handleMu.Lock()
	defer b.handleMu.Unlock()
	for id, ph := range handles {
		assert(ph.state >= validKey, "invalid handle")

		if alt, ok := b._handles[id]; !ok || alt.state < ph.state {
			b._handles[id] = ph
		}
	}
}

// getHandle retrieves the packageHandle for the given id.
func (b *typeCheckBatch) getHandle(id PackageID) *packageHandle {
	b.handleMu.Lock()
	defer b.handleMu.Unlock()
	return b._handles[id]
}

// TypeCheck parses and type-checks the specified packages,
// and returns them in the same order as the ids.
// The resulting packages' types may belong to different importers,
// so types from different packages are incommensurable.
//
// The resulting packages slice always contains len(ids) entries, though some
// of them may be nil if (and only if) the resulting error is non-nil.
//
// An error is returned if any of the requested packages fail to type-check.
// This is different from having type-checking errors: a failure to type-check
// indicates context cancellation or otherwise significant failure to perform
// the type-checking operation.
//
// In general, clients should never need to type-checked syntax for an
// intermediate test variant (ITV) package. Callers should apply
// RemoveIntermediateTestVariants (or equivalent) before this method, or any
// of the potentially type-checking methods below.
func (s *Snapshot) TypeCheck(ctx context.Context, ids ...PackageID) ([]*Package, error) {
	pkgs := make([]*Package, len(ids))
	post := func(i int, pkg *Package) {
		pkgs[i] = pkg
	}
	return pkgs, s.forEachPackage(ctx, ids, nil, post)
}

// Package visiting functions used by forEachPackage; see the documentation of
// forEachPackage for details.
type (
	preTypeCheck  = func(int, *packageHandle) bool // false => don't type check
	postTypeCheck = func(int, *Package)
)

// forEachPackage does a pre- and post- order traversal of the packages
// specified by ids using the provided pre and post functions.
//
// The pre func is optional. If set, pre is evaluated after the package
// handle has been constructed, but before type-checking. If pre returns false,
// type-checking is skipped for this package handle.
//
// post is called with a syntax package after type-checking completes
// successfully. It is only called if pre returned true.
//
// Both pre and post may be called concurrently.
func (s *Snapshot) forEachPackage(ctx context.Context, ids []PackageID, pre preTypeCheck, post postTypeCheck) error {
	ctx, done := event.Start(ctx, "cache.forEachPackage", label.PackageCount.Of(len(ids)))
	defer done()

	var (
		needIDs []PackageID // ids to type-check
		indexes []int       // original index of requested ids
	)

	// Check for existing active packages.
	//
	// Since gopls can't depend on package identity, any instance of the
	// requested package must be ok to return.
	//
	// This is an optimization to avoid redundant type-checking: following
	// changes to an open package many LSP clients send several successive
	// requests for package information for the modified package (semantic
	// tokens, code lens, inlay hints, etc.)
	for i, id := range ids {
		s.mu.Lock()
		ph, ok := s.packages.Get(id)
		s.mu.Unlock()
		if ok && ph.state >= validPackage {
			post(i, ph.pkgData.pkg)
		} else {
			needIDs = append(needIDs, id)
			indexes = append(indexes, i)
		}
	}

	if len(needIDs) == 0 {
		return nil // short cut: many call sites do not handle empty ids
	}

	b, release := s.acquireTypeChecking()
	defer release()

	handles, err := s.getPackageHandles(ctx, needIDs)
	if err != nil {
		return err
	}

	// Wrap the pre- and post- funcs to translate indices.
	var pre2 preTypeCheck
	if pre != nil {
		pre2 = func(i int, ph *packageHandle) bool {
			return pre(indexes[i], ph)
		}
	}
	post2 := func(i int, pkg *Package) {
		id := pkg.metadata.ID
		if ph := handles[id]; ph.isOpen && ph.state < validPackage {
			// Cache open type checked packages.
			ph = ph.clone()
			ph.pkgData = &packageData{
				fset:    pkg.FileSet(),
				imports: pkg.Types().Imports(),
				pkg:     pkg,
			}
			ph.state = validPackage

			s.mu.Lock()
			if alt, ok := s.packages.Get(id); !ok || alt.state < ph.state {
				s.packages.Set(id, ph, nil)
			}
			s.mu.Unlock()
		}

		post(indexes[i], pkg)
	}

	return b.query(ctx, needIDs, pre2, post2, handles)
}

// acquireTypeChecking joins or starts a concurrent type checking batch.
//
// The batch may be queried for package information using [typeCheckBatch.query].
// The second result must be called when the batch is no longer needed, to
// release the resource.
func (s *Snapshot) acquireTypeChecking() (*typeCheckBatch, func()) {
	s.typeCheckMu.Lock()
	defer s.typeCheckMu.Unlock()

	if s.batch == nil {
		assert(s.batchRef == 0, "miscounted type checking")
		s.batch = newTypeCheckBatch(s.view.parseCache, s.view.typ == GoPackagesDriverView)
	}
	s.batchRef++

	return s.batch, func() {
		s.typeCheckMu.Lock()
		defer s.typeCheckMu.Unlock()
		assert(s.batchRef > 0, "miscounted type checking 2")
		s.batchRef--
		if s.batchRef == 0 {
			s.batch = nil
		}
	}
}

// newTypeCheckBatch creates a new type checking batch using the provided
// shared parseCache.
//
// If a non-nil importGraph is provided, imports in this graph will be reused.
func newTypeCheckBatch(parseCache *parseCache, gopackagesdriver bool) *typeCheckBatch {
	return &typeCheckBatch{
		_handles:         make(map[PackageID]*packageHandle),
		parseCache:       parseCache,
		fset:             fileSetWithBase(reservedForParsing),
		cpulimit:         make(chan unit, runtime.GOMAXPROCS(0)),
		syntaxPackages:   newFutureCache[PackageID, *Package](false),      // don't persist syntax packages
		importPackages:   newFutureCache[PackageID, *types.Package](true), // ...but DO persist imports
		gopackagesdriver: gopackagesdriver,
	}
}

// query executes a traversal of package information in the given typeCheckBatch.
// For each package in importIDs, the package will be loaded "for import" (sans
// syntax).
//
// For each package in syntaxIDs, the package will be handled following the
// pre- and post- traversal logic of [Snapshot.forEachPackage].
//
// Package handles must be provided for each package in the forward transitive
// closure of either importIDs or syntaxIDs.
//
// TODO(rfindley): simplify this API by clarifying shared import graph and
// package handle logic.
func (b *typeCheckBatch) query(ctx context.Context, syntaxIDs []PackageID, pre preTypeCheck, post postTypeCheck, handles map[PackageID]*packageHandle) error {
	b.addHandles(handles)

	// Start a single goroutine for each requested package.
	//
	// Other packages are reached recursively, and will not be evaluated if they
	// are not needed.
	var g errgroup.Group
	for i, id := range syntaxIDs {
		g.Go(func() error {
			if ctx.Err() != nil {
				return ctx.Err()
			}
			return b.handleSyntaxPackage(ctx, i, id, pre, post)
		})
	}
	return g.Wait()
}

// TODO(rfindley): re-order the declarations below to read better from top-to-bottom.

// getImportPackage returns the *types.Package to use for importing the
// package referenced by id.
//
// This may be the package produced by type-checking syntax (as in the case
// where id is in the set of requested IDs), a package loaded from export data,
// or a package type-checked for import only.
func (b *typeCheckBatch) getImportPackage(ctx context.Context, id PackageID) (pkg *types.Package, err error) {
	return b.importPackages.get(ctx, id, func(ctx context.Context) (*types.Package, error) {
		ph := b.getHandle(id)

		// "unsafe" cannot be imported or type-checked.
		//
		// We check PkgPath, not id, as the structure of the ID
		// depends on the build system (in particular,
		// Bazel+gopackagesdriver appears to use something other than
		// "unsafe", though we aren't sure what; even 'go list' can
		// use "p [q.test]" for testing or if PGO is enabled.
		// See golang/go#60890.
		if ph.mp.PkgPath == "unsafe" {
			return types.Unsafe, nil
		}

		data, err := filecache.Get(exportDataKind, ph.key)
		if err == filecache.ErrNotFound {
			// No cached export data: type-check as fast as possible.
			return b.checkPackageForImport(ctx, ph)
		}
		if err != nil {
			return nil, fmt.Errorf("failed to read cache data for %s: %v", ph.mp.ID, err)
		}
		return b.importPackage(ctx, ph.mp, data)
	})
}

// handleSyntaxPackage handles one package from the ids slice.
//
// If type checking occurred while handling the package, it returns the
// resulting types.Package so that it may be used for importing.
//
// handleSyntaxPackage returns (nil, nil) if pre returned false.
func (b *typeCheckBatch) handleSyntaxPackage(ctx context.Context, i int, id PackageID, pre preTypeCheck, post postTypeCheck) error {
	ph := b.getHandle(id)
	if pre != nil && !pre(i, ph) {
		return nil // skip: not needed
	}

	// Check if we have a syntax package stored on ph.
	//
	// This was checked in [Snapshot.forEachPackage], but may have since changed.
	if ph.state >= validPackage {
		post(i, ph.pkgData.pkg)
		return nil
	}

	pkg, err := b.getPackage(ctx, ph)
	if err != nil {
		return err
	}

	post(i, pkg)
	return nil
}

// getPackage type checks one [Package] in the batch.
func (b *typeCheckBatch) getPackage(ctx context.Context, ph *packageHandle) (*Package, error) {
	return b.syntaxPackages.get(ctx, ph.mp.ID, func(ctx context.Context) (*Package, error) {
		// Wait for predecessors.
		// Record imports of this package to avoid redundant work in typesConfig.
		imports := make(map[PackagePath]*types.Package)
		fset := b.fset
		if ph.state >= validImports {
			for _, imp := range ph.pkgData.imports {
				imports[PackagePath(imp.Path())] = imp
			}
			// Reusing imports requires that their positions are mapped by the FileSet.
			fset = tokeninternal.CloneFileSet(ph.pkgData.fset)
		} else {
			var impMu sync.Mutex
			var g errgroup.Group
			for depPath, depID := range ph.mp.DepsByPkgPath {
				g.Go(func() error {
					imp, err := b.getImportPackage(ctx, depID)
					if err == nil {
						impMu.Lock()
						imports[depPath] = imp
						impMu.Unlock()
					}
					return err
				})
			}
			if err := g.Wait(); err != nil {
				// Failure to import a package should not abort the whole operation.
				// Stop only if the context was cancelled, a likely cause.
				// Import errors will be reported as type diagnostics.
				if ctx.Err() != nil {
					return nil, ctx.Err()
				}
			}
		}

		// Wait to acquire a CPU token.
		//
		// Note: it is important to acquire this token only after awaiting
		// predecessors, to avoid starvation.
		select {
		case <-ctx.Done():
			return nil, ctx.Err()
		case b.cpulimit <- unit{}:
			defer func() {
				<-b.cpulimit // release CPU token
			}()
		}

		// Compute the syntax package.
		p, err := b.checkPackage(ctx, fset, ph, imports)
		if err != nil {
			return nil, err // e.g. I/O error, cancelled
		}

		// Update caches.
		go storePackageResults(ctx, ph, p) // ...and write all packages to disk
		return p, nil
	})
}

// storePackageResults serializes and writes information derived from p to the
// file cache.
// The context is used only for logging; cancellation does not affect the operation.
func storePackageResults(ctx context.Context, ph *packageHandle, p *Package) {
	toCache := map[string][]byte{
		xrefsKind:       p.pkg.xrefs(),
		methodSetsKind:  p.pkg.methodsets().Encode(),
		testsKind:       p.pkg.tests().Encode(),
		diagnosticsKind: encodeDiagnostics(p.pkg.diagnostics),
	}

	if p.metadata.PkgPath != "unsafe" { // unsafe cannot be exported
		exportData, err := gcimporter.IExportShallow(p.pkg.fset, p.pkg.types, bug.Reportf)
		if err != nil {
			bug.Reportf("exporting package %v: %v", p.metadata.ID, err)
		} else {
			toCache[exportDataKind] = exportData
		}
	}

	for kind, data := range toCache {
		if err := filecache.Set(kind, ph.key, data); err != nil {
			event.Error(ctx, fmt.Sprintf("storing %s data for %s", kind, ph.mp.ID), err)
		}
	}
}

// Metadata implements the [metadata.Source] interface.
func (b *typeCheckBatch) Metadata(id PackageID) *metadata.Package {
	ph := b.getHandle(id)
	if ph == nil {
		return nil
	}
	return ph.mp
}

// importPackage loads the given package from its export data in p.exportData
// (which must already be populated).
func (b *typeCheckBatch) importPackage(ctx context.Context, mp *metadata.Package, data []byte) (*types.Package, error) {
	ctx, done := event.Start(ctx, "cache.typeCheckBatch.importPackage", label.Package.Of(string(mp.ID)))
	defer done()

	importLookup := importLookup(mp, b)

	thisPackage := types.NewPackage(string(mp.PkgPath), string(mp.Name))
	getPackages := func(items []gcimporter.GetPackagesItem) error {
		for i, item := range items {
			var id PackageID
			var pkg *types.Package
			if item.Path == string(mp.PkgPath) {
				id = mp.ID
				pkg = thisPackage

				// debugging issues #60904, #64235
				if pkg.Name() != item.Name {
					// This would mean that mp.Name != item.Name, so the
					// manifest in the export data of mp.PkgPath is
					// inconsistent with mp.Name. Or perhaps there
					// are duplicate PkgPath items in the manifest?
					if b.gopackagesdriver {
						return bug.Errorf("internal error: package name is %q, want %q (id=%q, path=%q) (see issue #60904) (using GOPACKAGESDRIVER)",
							pkg.Name(), item.Name, id, item.Path)
					} else {
						// There's a package in the export data with the same path as the
						// imported package, but a different name.
						//
						// This is observed to occur (very frequently!) in telemetry, yet
						// we don't yet have a plausible explanation: any self import or
						// circular import should have resulted in a broken import, which
						// can't be referenced by export data. (Any type qualified by the
						// broken import name will be invalid.)
						//
						// However, there are some mechanisms that could potentially be
						// involved:
						//  1. go/types will synthesize package names based on the import
						//     path for fake packages (but as mentioned above, I don't think
						//     these can be referenced by export data.)
						//  2. Test variants have the same path as non-test variant. Could
						//     that somehow be involved? (I don't see how, particularly using
						//     the go list driver, but nevertheless it's worth considering.)
						//  3. Command-line arguments and main packages may have special
						//     handling that we don't fully understand.
						// Try to sort these potential causes into unique stacks, as well
						// as a few other pathological scenarios.
						report := func() error {
							return bug.Errorf("internal error: package name is %q, want %q (id=%q, path=%q) (see issue #60904)",
								pkg.Name(), item.Name, id, item.Path)
						}
						impliedName := ""
						if i := strings.LastIndex(item.Path, "/"); i >= 0 {
							impliedName = item.Path[i+1:]
						}
						switch {
						case pkg.Name() == "":
							return report()
						case item.Name == "":
							return report()
						case metadata.IsCommandLineArguments(mp.ID):
							return report()
						case mp.ForTest != "":
							return report()
						case len(mp.CompiledGoFiles) == 0:
							return report()
						case len(mp.Errors) > 0:
							return report()
						case impliedName != "" && impliedName != string(mp.Name):
							return report()
						case len(mp.CompiledGoFiles) != len(mp.GoFiles):
							return report()
						case mp.Module == nil:
							return report()
						case mp.Name == "main":
							return report()
						default:
							return report()
						}
					}
				}
			} else {
				var alt PackageID
				id, alt = importLookup(PackagePath(item.Path))
				if alt != "" {
					// Any bug leading to this scenario would have already been reported
					// in importLookup.
					return fmt.Errorf("inconsistent metadata during import: for package path %q, found both IDs %q and %q", item.Path, id, alt)
				}
				var err error
				pkg, err = b.getImportPackage(ctx, id)
				if err != nil {
					return err
				}

				// We intentionally duplicate the bug.Errorf calls because
				// telemetry tells us only the program counter, not the message.

				// debugging issues #60904, #64235
				if pkg.Name() != item.Name {
					// This means that, while reading the manifest of the
					// export data of mp.PkgPath, one of its indirect
					// dependencies had a name that differs from the
					// Metadata.Name
					return bug.Errorf("internal error: package name is %q, want %q (id=%q, path=%q) (see issue #60904)",
						pkg.Name(), item.Name, id, item.Path)
				}
			}
			items[i].Pkg = pkg

		}
		return nil
	}

	// Importing is potentially expensive, and might not encounter cancellations
	// via dependencies (e.g. if they have already been evaluated).
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}

	imported, err := gcimporter.IImportShallow(b.fset, getPackages, data, string(mp.PkgPath), bug.Reportf)
	if err != nil {
		return nil, fmt.Errorf("import failed for %q: %v", mp.ID, err)
	}
	return imported, nil
}

// checkPackageForImport type checks, but skips function bodies and does not
// record syntax information.
func (b *typeCheckBatch) checkPackageForImport(ctx context.Context, ph *packageHandle) (*types.Package, error) {
	ctx, done := event.Start(ctx, "cache.typeCheckBatch.checkPackageForImport", label.Package.Of(string(ph.mp.ID)))
	defer done()

	onError := func(e error) {
		// Ignore errors for exporting.
	}
	cfg := b.typesConfig(ctx, ph.localInputs, nil, onError)
	cfg.IgnoreFuncBodies = true

	// Parse the compiled go files, bypassing the parse cache as packages checked
	// for import are unlikely to get cache hits. Additionally, we can optimize
	// parsing slightly by not passing parser.ParseComments.
	pgfs := make([]*parsego.File, len(ph.localInputs.compiledGoFiles))
	{
		var group errgroup.Group
		// Set an arbitrary concurrency limit; we want some parallelism but don't
		// need GOMAXPROCS, as there is already a lot of concurrency among calls to
		// checkPackageForImport.
		//
		// TODO(rfindley): is there a better way to limit parallelism here? We could
		// have a global limit on the type-check batch, but would have to be very
		// careful to avoid starvation.
		group.SetLimit(4)
		for i, fh := range ph.localInputs.compiledGoFiles {
			group.Go(func() error {
				pgf, err := parseGoImpl(ctx, b.fset, fh, parser.SkipObjectResolution, false)
				pgfs[i] = pgf
				return err
			})
		}
		if err := group.Wait(); err != nil {
			return nil, err // cancelled, or catastrophic error (e.g. missing file)
		}
	}
	pkg := types.NewPackage(string(ph.localInputs.pkgPath), string(ph.localInputs.name))
	check := types.NewChecker(cfg, b.fset, pkg, nil)

	files := make([]*ast.File, len(pgfs))
	for i, pgf := range pgfs {
		files[i] = pgf.File
	}

	// Type checking is expensive, and we may not have encountered cancellations
	// via parsing (e.g. if we got nothing but cache hits for parsed files).
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}

	_ = check.Files(files) // ignore errors

	// If the context was cancelled, we may have returned a ton of transient
	// errors to the type checker. Swallow them.
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}

	// Asynchronously record export data.
	go func() {
		exportData, err := gcimporter.IExportShallow(b.fset, pkg, bug.Reportf)
		if err != nil {
			// Internal error; the stack will have been reported via
			// bug.Reportf within IExportShallow, so there's not much
			// to do here (issue #71067).
			event.Error(ctx, "IExportShallow failed", err, label.Package.Of(string(ph.mp.ID)))
			return
		}
		if err := filecache.Set(exportDataKind, ph.key, exportData); err != nil {
			event.Error(ctx, fmt.Sprintf("storing export data for %s", ph.mp.ID), err)
		}
	}()
	return pkg, nil
}

// importLookup returns a function that may be used to look up a package ID for
// a given package path, based on the forward transitive closure of the initial
// package (id).
//
// If the second result is non-empty, it is another ID discovered in the import
// graph for the same package path. This means the import graph is
// incoherent--see #63822 and the long comment below.
//
// The resulting function is not concurrency safe.
func importLookup(mp *metadata.Package, source metadata.Source) func(PackagePath) (id, altID PackageID) {
	assert(mp != nil, "nil metadata")

	// This function implements an incremental depth first scan through the
	// package imports. Previous implementations of import mapping built the
	// entire PackagePath->PackageID mapping eagerly, but that resulted in a
	// large amount of unnecessary work: most imports are either directly
	// imported, or found through a shallow scan.

	// impMap memoizes the lookup of package paths.
	impMap := map[PackagePath]PackageID{
		mp.PkgPath: mp.ID,
	}

	// altIDs records alternative IDs for the given path, to report inconsistent
	// metadata.
	var altIDs map[PackagePath]PackageID

	// pending is a FIFO queue of package metadata that has yet to have its
	// dependencies fully scanned.
	// Invariant: all entries in pending are already mapped in impMap.
	pending := []*metadata.Package{mp}

	// search scans children the next package in pending, looking for pkgPath.
	// Invariant: whenever search is called, pkgPath is not yet mapped.
	search := func(pkgPath PackagePath) (id PackageID, found bool) {
		pkg := pending[0]
		pending = pending[1:]
		for depPath, depID := range pkg.DepsByPkgPath {
			if prevID, ok := impMap[depPath]; ok {
				// debugging #63822
				if prevID != depID {
					if altIDs == nil {
						altIDs = make(map[PackagePath]PackageID)
					}
					if _, ok := altIDs[depPath]; !ok {
						altIDs[depPath] = depID
					}
					prev := source.Metadata(prevID)
					curr := source.Metadata(depID)
					switch {
					case prev == nil || curr == nil:
						bug.Reportf("inconsistent view of dependencies (missing dep)")
					case prev.ForTest != curr.ForTest:
						// This case is unfortunately understood to be possible.
						//
						// To explain this, consider a package a_test testing the package
						// a, and for brevity denote by b' the intermediate test variant of
						// the package b, which is created for the import graph of a_test,
						// if b imports a.
						//
						// Now imagine that we have the following import graph, where
						// higher packages import lower ones.
						//
						//       a_test
						//      / \
						//     b'  c
						//    / \ /
						//   a   d
						//
						// In this graph, there is one intermediate test variant b',
						// because b imports a and so b' must hold the test variant import.
						//
						// Now, imagine that an on-disk change (perhaps due to a branch
						// switch) affects the above import graph such that d imports a.
						//
						//       a_test
						//      / \
						//     b'  c*
						//    / \ /
						//   /   d*
						//  a---/
						//
						// In this case, c and d should really be intermediate test
						// variants, because they reach a. However, suppose that gopls does
						// not know this yet (as indicated by '*').
						//
						// Now suppose that the metadata of package c is invalidated, for
						// example due to a change in an unrelated import or an added file.
						// This will invalidate the metadata of c and a_test (but NOT b),
						// and now gopls observes this graph:
						//
						//       a_test
						//      / \
						//     b'  c'
						//    /|   |
						//   / d   d'
						//  a-----/
						//
						// That is: a_test now sees c', which sees d', but since b was not
						// invalidated, gopls still thinks that b' imports d (not d')!
						//
						// The problem, of course, is that gopls never observed the change
						// to d, which would have invalidated b. This may be due to racing
						// file watching events, in which case the problem should
						// self-correct when gopls sees the change to d, or it may be due
						// to d being outside the coverage of gopls' file watching glob
						// patterns, or it may be due to buggy or entirely absent
						// client-side file watching.
						//
						// TODO(rfindley): fix this, one way or another. It would be hard
						// or impossible to repair gopls' state here, during type checking.
						// However, we could perhaps reload metadata in Snapshot.load until
						// we achieve a consistent state, or better, until the loaded state
						// is consistent with our view of the filesystem, by making the Go
						// command report digests of the files it reads. Both of those are
						// tricker than they may seem, and have significant performance
						// implications.
					default:
						bug.Reportf("inconsistent view of dependencies")
					}
				}
				continue
			}
			impMap[depPath] = depID

			dep := source.Metadata(depID)
			assert(dep != nil, "missing dep metadata")

			pending = append(pending, dep)
			if depPath == pkgPath {
				// Don't return early; finish processing pkg's deps.
				id = depID
				found = true
			}
		}
		return id, found
	}

	return func(pkgPath PackagePath) (id, altID PackageID) {
		if id, ok := impMap[pkgPath]; ok {
			return id, altIDs[pkgPath]
		}
		for len(pending) > 0 {
			if id, found := search(pkgPath); found {
				return id, altIDs[pkgPath]
			}
		}
		return "", ""
	}
}

// A packageState is the state of a [packageHandle]; see below for details.
type packageState uint8

const (
	validMetadata  packageState = iota // the package has valid metadata
	validLocalData                     // local package files have been analyzed
	validKey                           // dependencies have been analyzed, and key produced
	validImports                       // pkgData.fset and pkgData.imports are valid
	validPackage                       // pkgData.pkg is valid
)

// A packageHandle holds information derived from a metadata.Package, and
// records its degree of validity as state changes occur: successful analysis
// causes the state to progress; invalidation due to changes causes it to
// regress.
//
// In the initial state (validMetadata), all we know is the metadata for the
// package itself. This is the lowest state, and it cannot become invalid
// because the metadata for a given snapshot never changes. (Each handle is
// implicitly associated with a Snapshot.)
//
// After the files of the package have been read (validLocalData), we can
// perform computations that are local to that package, such as parsing, or
// building the symbol reference graph (SRG). This information is invalidated
// by a change to any file in the package. The local information is thus
// sufficient to form a cache key for saved parsed trees or the SRG.
//
// Once all dependencies have been analyzed (validKey), we can type-check the
// package. This information is invalidated by any change to the package
// itself, or to any dependency that is transitively reachable through the SRG.
// The cache key for saved type information must thus incorporate information
// from all reachable dependencies. This reachability analysis implements what
// we sometimes refer to as "precise pruning", or fine-grained invalidation:
// https://go.dev/blog/gopls-scalability#invalidation
//
// After type checking, package information for open packages is cached in the
// pkgData field (validPackage), to optimize subsequent requests oriented
// around open files.
//
// Following a change, the packageHandle is cloned in the new snapshot with a
// new state set to its least known valid state, as described above: if package
// files changed, it is reset to validMetadata; if dependencies changed, it is
// reset to validLocalData. However, the derived data from its previous state
// is not yet removed, as keys may not have changed after they are reevaluated,
// in which case we can avoid recomputing the derived data. In particular, if
// the cache key did not change, the pkgData field (if set) remains valid. As a
// special case, if the cache key did change, but none of the keys of
// dependencies changed, the pkgData.fset and pkgData.imports fields are still
// valid, though the pkgData.pkg field is not (validImports).
//
// See [packageHandleBuilder.evaluatePackageHandle] for more details of the
// reevaluation algorithm.
//
// packageHandles are immutable once they are stored in the Snapshot.packages
// map: any changes to packageHandle fields evaluatePackageHandle must be made
// to a cloned packageHandle, and inserted back into Snapshot.packages. Data
// referred to by the packageHandle may be shared by multiple clones, and so
// referents must not be mutated.
type packageHandle struct {
	mp *metadata.Package

	// state indicates which data below are still valid.
	state packageState

	// Local data:

	// loadDiagnostics memoizes the result of processing error messages from
	// go/packages (i.e. `go list`).
	//
	// These are derived from metadata using a snapshot. Since they depend on
	// file contents (for translating positions), they should theoretically be
	// invalidated by file changes, but historically haven't been. In practice
	// they are rare and indicate a fundamental error that needs to be corrected
	// before development can continue, so it may not be worth significant
	// engineering effort to implement accurate invalidation here.
	//
	// TODO(rfindley): loadDiagnostics are out of place here, as they don't
	// directly relate to type checking. We should perhaps move the caching of
	// load diagnostics to an entirely separate component, so that Packages need
	// only be concerned with parsing and type checking.
	// (Nevertheless, since the lifetime of load diagnostics matches that of the
	// Metadata, it is convenient to memoize them here.)
	loadDiagnostics []*Diagnostic
	// localInputs holds all local type-checking localInputs, excluding
	// dependencies.
	localInputs *typeCheckInputs
	// isOpen reports whether the package has any open files.
	isOpen bool
	// localKey is a hash of localInputs.
	localKey file.Hash
	// refs is the result of syntactic dependency analysis produced by the
	// typerefs package. Derived from localInputs.
	refs map[string][]typerefs.Symbol

	// Keys, computed through reachability analysis of dependencies.

	// depKeys records the key of each dependency that was used to calculate the
	// key below. If state < validKey, we must re-check that each still matches.
	depKeys map[PackageID]file.Hash

	// reachable is used to filter reachable package paths for go/analysis fact
	// importing.
	reachable *bloom.Filter

	// key is the hashed key for the package.
	//
	// It includes the all bits of the transitive closure of
	// dependencies's sources.
	key file.Hash

	// pkgData caches data derived from type checking the package.
	// This data is set during [Snapshot.forEachPackage], and may be partially
	// invalidated in [packageHandleBuilder.evaluatePackageHandle].
	//
	// If state == validPackage, all fields of pkgData are valid. If state ==
	// validImports, only fset and imports are valid.
	pkgData *packageData
}

// packageData holds the (possibly partial) result of type checking this
// package. See the pkgData field of [packageHandle].
//
// packageData instances are immutable.
type packageData struct {
	fset    *token.FileSet   // pkg.FileSet()
	imports []*types.Package // pkg.Types().Imports()
	pkg     *Package         // pkg, if state==validPackage; nil in lower states
}

// clone returns a shallow copy of the receiver.
func (ph *packageHandle) clone() *packageHandle {
	clone := *ph
	return &clone
}

// getPackageHandles gets package handles for all given ids and their
// dependencies, recursively. The resulting [packageHandle] values are fully
// evaluated (their state will be at least validKey).
func (s *Snapshot) getPackageHandles(ctx context.Context, ids []PackageID) (map[PackageID]*packageHandle, error) {
	// perform a two-pass traversal.
	//
	// On the first pass, build up a bidirectional graph of handle nodes, and collect leaves.
	// Then build package handles from bottom up.
	b := &packageHandleBuilder{
		s:              s,
		transitiveRefs: make(map[typerefs.IndexID]*partialRefs),
		nodes:          make(map[typerefs.IndexID]*handleNode),
	}

	meta := s.MetadataGraph()

	var leaves []*handleNode
	var makeNode func(*handleNode, PackageID) *handleNode
	makeNode = func(from *handleNode, id PackageID) *handleNode {
		idxID := s.view.pkgIndex.IndexID(id)
		n, ok := b.nodes[idxID]
		if !ok {
			mp := meta.Packages[id]
			if mp == nil {
				panic(fmt.Sprintf("nil metadata for %q", id))
			}
			n = &handleNode{
				mp:              mp,
				idxID:           idxID,
				unfinishedSuccs: int32(len(mp.DepsByPkgPath)),
			}
			if n.unfinishedSuccs == 0 {
				leaves = append(leaves, n)
			} else {
				n.succs = make(map[PackageID]*handleNode, n.unfinishedSuccs)
			}
			b.nodes[idxID] = n
			for _, depID := range mp.DepsByPkgPath {
				n.succs[depID] = makeNode(n, depID)
			}
		}
		// Add edge from predecessor.
		if from != nil {
			n.preds = append(n.preds, from)
		}
		return n
	}
	for _, id := range ids {
		if ctx.Err() != nil {
			return nil, ctx.Err()
		}
		makeNode(nil, id)
	}

	g, ctx := errgroup.WithContext(ctx)

	// files are preloaded, so building package handles is CPU-bound.
	//
	// Note that we can't use g.SetLimit, as that could result in starvation:
	// g.Go blocks until a slot is available, and so all existing goroutines
	// could be blocked trying to enqueue a predecessor.
	limiter := make(chan unit, runtime.GOMAXPROCS(0))

	var enqueue func(*handleNode)
	enqueue = func(n *handleNode) {
		g.Go(func() error {
			limiter <- unit{}
			defer func() { <-limiter }()

			if ctx.Err() != nil {
				return ctx.Err()
			}

			if err := b.evaluatePackageHandle(ctx, n); err != nil {
				return err
			}

			for _, pred := range n.preds {
				if atomic.AddInt32(&pred.unfinishedSuccs, -1) == 0 {
					enqueue(pred)
				}
			}
			return nil
		})
	}
	for _, leaf := range leaves {
		enqueue(leaf)
	}

	if err := g.Wait(); err != nil {
		return nil, err
	}

	// Copy handles into the result map.
	handles := make(map[PackageID]*packageHandle, len(b.nodes))
	for _, v := range b.nodes {
		assert(v.ph != nil, "nil handle")
		handles[v.mp.ID] = v.ph
	}

	return handles, nil
}

// A packageHandleBuilder computes a batch of packageHandles concurrently,
// sharing computed transitive reachability sets used to compute package keys.
type packageHandleBuilder struct {
	s *Snapshot

	// nodes are assembled synchronously.
	nodes map[typerefs.IndexID]*handleNode

	// transitiveRefs is incrementally evaluated as package handles are built.
	transitiveRefsMu sync.Mutex
	transitiveRefs   map[typerefs.IndexID]*partialRefs // see getTransitiveRefs
}

// A handleNode represents a to-be-computed packageHandle within a graph of
// predecessors and successors.
//
// It is used to implement a bottom-up construction of packageHandles.
type handleNode struct {
	mp              *metadata.Package
	idxID           typerefs.IndexID
	ph              *packageHandle
	preds           []*handleNode
	succs           map[PackageID]*handleNode
	unfinishedSuccs int32
}

// partialRefs maps names declared by a given package to their set of
// transitive references.
//
// If complete is set, refs is known to be complete for the package in
// question. Otherwise, it may only map a subset of all names declared by the
// package.
type partialRefs struct {
	refs     map[string]*typerefs.PackageSet
	complete bool
}

// getTransitiveRefs gets or computes the set of transitively reachable
// packages for each exported name in the package specified by id.
//
// The operation may fail if building a predecessor failed. If and only if this
// occurs, the result will be nil.
func (b *packageHandleBuilder) getTransitiveRefs(pkgID PackageID) map[string]*typerefs.PackageSet {
	b.transitiveRefsMu.Lock()
	defer b.transitiveRefsMu.Unlock()

	idxID := b.s.view.pkgIndex.IndexID(pkgID)
	trefs, ok := b.transitiveRefs[idxID]
	if !ok {
		trefs = &partialRefs{
			refs: make(map[string]*typerefs.PackageSet),
		}
		b.transitiveRefs[idxID] = trefs
	}

	if !trefs.complete {
		trefs.complete = true
		node := b.nodes[idxID]
		for name := range node.ph.refs {
			if ('A' <= name[0] && name[0] <= 'Z') || token.IsExported(name) {
				if _, ok := trefs.refs[name]; !ok {
					pkgs := b.s.view.pkgIndex.NewSet()
					for _, sym := range node.ph.refs[name] {
						pkgs.Add(sym.Package)
						otherSet := b.getOneTransitiveRefLocked(sym)
						pkgs.Union(otherSet)
					}
					trefs.refs[name] = pkgs
				}
			}
		}
	}

	return trefs.refs
}

// getOneTransitiveRefLocked computes the full set packages transitively
// reachable through the given sym reference.
//
// It may return nil if the reference is invalid (i.e. the referenced name does
// not exist).
func (b *packageHandleBuilder) getOneTransitiveRefLocked(sym typerefs.Symbol) *typerefs.PackageSet {
	assert(token.IsExported(sym.Name), "expected exported symbol")

	trefs := b.transitiveRefs[sym.Package]
	if trefs == nil {
		trefs = &partialRefs{
			refs:     make(map[string]*typerefs.PackageSet),
			complete: false,
		}
		b.transitiveRefs[sym.Package] = trefs
	}

	pkgs, ok := trefs.refs[sym.Name]
	if ok && pkgs == nil {
		// See below, where refs is set to nil before recursing.
		bug.Reportf("cycle detected to %q in reference graph", sym.Name)
	}

	// Note that if (!ok && trefs.complete), the name does not exist in the
	// referenced package, and we should not write to trefs as that may introduce
	// a race.
	if !ok && !trefs.complete {
		n := b.nodes[sym.Package]
		if n == nil {
			// We should always have IndexID in our node set, because symbol references
			// should only be recorded for packages that actually exist in the import graph.
			//
			// However, it is not easy to prove this (typerefs are serialized and
			// deserialized), so make this code temporarily defensive while we are on a
			// point release.
			//
			// TODO(rfindley): in the future, we should turn this into an assertion.
			bug.Reportf("missing reference to package %s", b.s.view.pkgIndex.PackageID(sym.Package))
			return nil
		}

		// Break cycles. This is perhaps overly defensive as cycles should not
		// exist at this point: metadata cycles should have been broken at load
		// time, and intra-package reference cycles should have been contracted by
		// the typerefs algorithm.
		//
		// See the "cycle detected" bug report above.
		trefs.refs[sym.Name] = nil

		pkgs := b.s.view.pkgIndex.NewSet()
		for _, sym2 := range n.ph.refs[sym.Name] {
			pkgs.Add(sym2.Package)
			otherSet := b.getOneTransitiveRefLocked(sym2)
			pkgs.Union(otherSet)
		}
		trefs.refs[sym.Name] = pkgs
	}

	return pkgs
}

// evaluatePackageHandle recomputes the derived information in the package handle.
// On success, the handle's state is validKey.
//
// evaluatePackageHandle must only be called from getPackageHandles.
func (b *packageHandleBuilder) evaluatePackageHandle(ctx context.Context, n *handleNode) (err error) {
	b.s.mu.Lock()
	ph, hit := b.s.packages.Get(n.mp.ID)
	b.s.mu.Unlock()

	defer func() {
		if err == nil {
			assert(ph.state >= validKey, "invalid handle")

			// Record the now valid key in the snapshot.
			// There may be a race, so avoid the write if the recorded handle is
			// already valid.
			b.s.mu.Lock()
			if alt, ok := b.s.packages.Get(n.mp.ID); !ok || alt.state < ph.state {
				b.s.packages.Set(n.mp.ID, ph, nil)
			} else {
				ph = alt
			}
			b.s.mu.Unlock()

			// Initialize n.ph.
			n.ph = ph
		}
	}()

	if hit && ph.state >= validKey {
		return nil // already valid
	} else {
		// We'll need to update the package handle. Since this could happen
		// concurrently, make a copy.
		if hit {
			ph = ph.clone() // state < validKey
		} else {
			ph = &packageHandle{
				mp:    n.mp,
				state: validMetadata,
			}
		}
	}

	// Invariant: ph is either
	// - a new handle in state validMetadata, or
	// - a clone of an existing handle in state validMetadata or validLocalData.

	// State transition: validMetadata -> validLocalInputs.
	localKeyChanged := false
	if ph.state < validLocalData {
		prevLocalKey := ph.localKey // may be zero
		// No package handle: read and analyze the package syntax.
		inputs, err := b.s.typeCheckInputs(ctx, n.mp)
		if err != nil {
			return err
		}
		refs, err := b.s.typerefs(ctx, n.mp, inputs.compiledGoFiles)
		if err != nil {
			return err
		}
		ph.loadDiagnostics = computeLoadDiagnostics(ctx, b.s, n.mp)
		ph.localInputs = inputs

	checkOpen:
		for _, files := range [][]file.Handle{inputs.goFiles, inputs.compiledGoFiles} {
			for _, fh := range files {
				if _, ok := fh.(*overlay); ok {
					ph.isOpen = true
					break checkOpen
				}
			}
		}
		if !ph.isOpen {
			// ensure we don't hold data for closed packages
			ph.pkgData = nil
		}
		ph.localKey = localPackageKey(inputs)
		ph.refs = refs
		ph.state = validLocalData
		localKeyChanged = ph.localKey != prevLocalKey
	}

	assert(ph.state == validLocalData, "unexpected handle state")

	// State transition: validLocalInputs -> validKey

	// Check if any dependencies have actually changed.
	depsChanged := true
	if ph.depKeys != nil { // ph was previously evaluated
		depsChanged = len(ph.depKeys) != len(n.succs)
		if !depsChanged {
			for id, succ := range n.succs {
				oldKey, ok := ph.depKeys[id]
				assert(ok, "missing dep")
				if oldKey != succ.ph.key {
					depsChanged = true
					break
				}
			}
		}
	}

	// Optimization: if the local package information did not change, nor did any
	// of the dependencies, we don't need to re-run the reachability algorithm.
	//
	// Concretely: suppose A -> B -> C -> D, where '->' means "imports". If I
	// type in a function body of D, I will probably invalidate types in D that C
	// uses, because positions change, and therefore the package key of C will
	// change. But B probably doesn't reach any types in D, and therefore the
	// package key of B will not change. We still need to re-run the reachability
	// algorithm on B to confirm. But if the key of B did not change, we don't
	// even need to run the reachability algorithm on A.
	if !localKeyChanged && !depsChanged {
		ph.state = validKey
	}

	keyChanged := false
	if ph.state < validKey {
		prevKey := ph.key

		// If we get here, it must be the case that deps have changed, so we must
		// run the reachability algorithm.
		ph.depKeys = make(map[PackageID]file.Hash)

		// See the typerefs package: the reachable set of packages is defined to be
		// the set of packages containing syntax that is reachable through the
		// symbol reference graph starting at the exported symbols in the
		// dependencies of ph.
		reachable := b.s.view.pkgIndex.NewSet()
		for depID, succ := range n.succs {
			ph.depKeys[depID] = succ.ph.key
			reachable.Add(succ.idxID)
			trefs := b.getTransitiveRefs(succ.mp.ID)
			assert(trefs != nil, "nil trefs")
			for _, set := range trefs {
				reachable.Union(set)
			}
		}

		// Collect reachable nodes.
		var reachableNodes []*handleNode
		// In the presence of context cancellation, any package may be missing.
		// We need all dependencies to produce a key.
		reachable.Elems(func(id typerefs.IndexID) {
			dh := b.nodes[id]
			if dh == nil {
				// Previous code reported an error (not a bug) here.
				bug.Reportf("missing reachable node for %v", id)
			} else {
				reachableNodes = append(reachableNodes, dh)
			}
		})

		// Sort for stability.
		sort.Slice(reachableNodes, func(i, j int) bool {
			return reachableNodes[i].mp.ID < reachableNodes[j].mp.ID
		})

		// Key is the hash of the local key of this package, and the local key of
		// all reachable packages.
		depHasher := sha256.New()
		depHasher.Write(ph.localKey[:])
		reachablePaths := make([]string, len(reachableNodes))
		for i, dh := range reachableNodes {
			depHasher.Write(dh.ph.localKey[:])
			reachablePaths[i] = string(dh.ph.mp.PkgPath)
		}
		depHasher.Sum(ph.key[:0])
		ph.reachable = bloom.NewFilter(reachablePaths)
		ph.state = validKey
		keyChanged = ph.key != prevKey
	}

	assert(ph.state == validKey, "unexpected handle state")

	// Validate ph.pkgData, upgrading state if the package or its imports are
	// still valid.
	if ph.pkgData != nil {
		pkgData := *ph.pkgData // make a copy
		ph.pkgData = &pkgData
		ph.state = validPackage
		if keyChanged || ph.pkgData.pkg == nil {
			ph.pkgData.pkg = nil // ensure we don't hold on to stale packages
			ph.state = validImports
		}
		if depsChanged {
			ph.pkgData = nil
			ph.state = validKey
		}
	}

	// Postcondition: state >= validKey

	return nil
}

// typerefs returns typerefs for the package described by m and cgfs, after
// either computing it or loading it from the file cache.
func (s *Snapshot) typerefs(ctx context.Context, mp *metadata.Package, cgfs []file.Handle) (map[string][]typerefs.Symbol, error) {
	imports := make(map[ImportPath]*metadata.Package)
	for impPath, id := range mp.DepsByImpPath {
		if id != "" {
			imports[impPath] = s.Metadata(id)
		}
	}

	data, err := s.typerefData(ctx, mp.ID, imports, cgfs)
	if err != nil {
		return nil, err
	}
	classes := typerefs.Decode(s.view.pkgIndex, data)
	refs := make(map[string][]typerefs.Symbol)
	for _, class := range classes {
		for _, decl := range class.Decls {
			refs[decl] = class.Refs
		}
	}
	return refs, nil
}

// typerefData retrieves encoded typeref data from the filecache, or computes it on
// a cache miss.
func (s *Snapshot) typerefData(ctx context.Context, id PackageID, imports map[ImportPath]*metadata.Package, cgfs []file.Handle) ([]byte, error) {
	key := typerefsKey(id, imports, cgfs)
	if data, err := filecache.Get(typerefsKind, key); err == nil {
		return data, nil
	} else if err != filecache.ErrNotFound {
		bug.Reportf("internal error reading typerefs data: %v", err)
		// Unexpected error: treat as cache miss, and fall through.
	}

	pgfs, err := s.view.parseCache.parseFiles(ctx, token.NewFileSet(), parsego.Full&^parser.ParseComments, true, cgfs...)
	if err != nil {
		return nil, err
	}
	data := typerefs.Encode(pgfs, imports)

	// Store the resulting data in the cache.
	go func() {
		if err := filecache.Set(typerefsKind, key, data); err != nil {
			event.Error(ctx, fmt.Sprintf("storing typerefs data for %s", id), err)
		}
	}()

	return data, nil
}

// typerefsKey produces a key for the reference information produced by the
// typerefs package.
func typerefsKey(id PackageID, imports map[ImportPath]*metadata.Package, compiledGoFiles []file.Handle) file.Hash {
	hasher := sha256.New()

	fmt.Fprintf(hasher, "typerefs: %s\n", id)

	for importPath, imp := range moremaps.Sorted(imports) {
		// TODO(rfindley): strength reduce the typerefs.Export API to guarantee
		// that it only depends on these attributes of dependencies.
		fmt.Fprintf(hasher, "import %s %s %s", importPath, imp.ID, imp.Name)
	}

	fmt.Fprintf(hasher, "compiledGoFiles: %d\n", len(compiledGoFiles))
	for _, fh := range compiledGoFiles {
		fmt.Fprintln(hasher, fh.Identity())
	}

	var hash [sha256.Size]byte
	hasher.Sum(hash[:0])
	return hash
}

// typeCheckInputs contains the inputs of a call to typeCheckImpl, which
// type-checks a package.
//
// Part of the purpose of this type is to keep type checking in-sync with the
// package handle key, by explicitly identifying the inputs to type checking.
type typeCheckInputs struct {
	id PackageID

	// Used for type checking:
	pkgPath                  PackagePath
	name                     PackageName
	goFiles, compiledGoFiles []file.Handle
	sizes                    types.Sizes
	depsByImpPath            map[ImportPath]PackageID
	goVersion                string // packages.Module.GoVersion, e.g. "1.18"

	// Used for type check diagnostics:
	// TODO(rfindley): consider storing less data in gobDiagnostics, and
	// interpreting each diagnostic in the context of a fixed set of options.
	// Then these fields need not be part of the type checking inputs.
	supportsRelatedInformation bool
	linkTarget                 string
	viewType                   ViewType
}

func (s *Snapshot) typeCheckInputs(ctx context.Context, mp *metadata.Package) (*typeCheckInputs, error) {
	// Read both lists of files of this package.
	//
	// Parallelism is not necessary here as the files will have already been
	// pre-read at load time.
	//
	// goFiles aren't presented to the type checker--nor
	// are they included in the key, unsoundly--but their
	// syntax trees are available from (*pkg).File(URI).
	// TODO(adonovan): consider parsing them on demand?
	// The need should be rare.
	goFiles, err := readFiles(ctx, s, mp.GoFiles)
	if err != nil {
		return nil, err
	}
	compiledGoFiles, err := readFiles(ctx, s, mp.CompiledGoFiles)
	if err != nil {
		return nil, err
	}

	goVersion := ""
	if mp.Module != nil && mp.Module.GoVersion != "" {
		goVersion = mp.Module.GoVersion
	} else {
		// Fall back on the go version implied by the ambient Go command.
		goVersion = fmt.Sprintf("1.%d", s.View().GoVersion())
	}

	return &typeCheckInputs{
		id:              mp.ID,
		pkgPath:         mp.PkgPath,
		name:            mp.Name,
		goFiles:         goFiles,
		compiledGoFiles: compiledGoFiles,
		sizes:           mp.TypesSizes,
		depsByImpPath:   mp.DepsByImpPath,
		goVersion:       goVersion,

		supportsRelatedInformation: s.Options().RelatedInformationSupported,
		linkTarget:                 s.Options().LinkTarget,
		viewType:                   s.view.typ,
	}, nil
}

// readFiles reads the content of each file URL from the source
// (e.g. snapshot or cache).
func readFiles(ctx context.Context, fs file.Source, uris []protocol.DocumentURI) (_ []file.Handle, err error) {
	fhs := make([]file.Handle, len(uris))
	for i, uri := range uris {
		fhs[i], err = fs.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
	}
	return fhs, nil
}

// localPackageKey returns a key for local inputs into type-checking, excluding
// dependency information: files, metadata, and configuration.
func localPackageKey(inputs *typeCheckInputs) file.Hash {
	hasher := sha256.New()

	// In principle, a key must be the hash of an
	// unambiguous encoding of all the relevant data.
	// If it's ambiguous, we risk collisions.

	// package identifiers
	fmt.Fprintf(hasher, "package: %s %s %s\n", inputs.id, inputs.name, inputs.pkgPath)

	// module Go version
	fmt.Fprintf(hasher, "go %s\n", inputs.goVersion)

	// import map
	for impPath, depID := range moremaps.Sorted(inputs.depsByImpPath) {
		fmt.Fprintf(hasher, "import %s %s", impPath, depID)
	}

	// file names and contents
	fmt.Fprintf(hasher, "compiledGoFiles: %d\n", len(inputs.compiledGoFiles))
	for _, fh := range inputs.compiledGoFiles {
		fmt.Fprintln(hasher, fh.Identity())
	}
	fmt.Fprintf(hasher, "goFiles: %d\n", len(inputs.goFiles))
	for _, fh := range inputs.goFiles {
		fmt.Fprintln(hasher, fh.Identity())
	}

	// types sizes
	wordSize := inputs.sizes.Sizeof(types.Typ[types.Int])
	maxAlign := inputs.sizes.Alignof(types.NewPointer(types.Typ[types.Int64]))
	fmt.Fprintf(hasher, "sizes: %d %d\n", wordSize, maxAlign)

	fmt.Fprintf(hasher, "relatedInformation: %t\n", inputs.supportsRelatedInformation)
	fmt.Fprintf(hasher, "linkTarget: %s\n", inputs.linkTarget)
	fmt.Fprintf(hasher, "viewType: %d\n", inputs.viewType)

	var hash [sha256.Size]byte
	hasher.Sum(hash[:0])
	return hash
}

// checkPackage type checks the parsed source files in compiledGoFiles.
// (The resulting pkg also holds the parsed but not type-checked goFiles.)
// deps holds the future results of type-checking the direct dependencies.
func (b *typeCheckBatch) checkPackage(ctx context.Context, fset *token.FileSet, ph *packageHandle, imports map[PackagePath]*types.Package) (*Package, error) {
	inputs := ph.localInputs
	ctx, done := event.Start(ctx, "cache.typeCheckBatch.checkPackage", label.Package.Of(string(inputs.id)))
	defer done()

	pkg := &syntaxPackage{
		id:         inputs.id,
		fset:       fset, // must match parse call below
		types:      types.NewPackage(string(inputs.pkgPath), string(inputs.name)),
		typesSizes: inputs.sizes,
		typesInfo: &types.Info{
			Types:        make(map[ast.Expr]types.TypeAndValue),
			Defs:         make(map[*ast.Ident]types.Object),
			Uses:         make(map[*ast.Ident]types.Object),
			Implicits:    make(map[ast.Node]types.Object),
			Instances:    make(map[*ast.Ident]types.Instance),
			Selections:   make(map[*ast.SelectorExpr]*types.Selection),
			Scopes:       make(map[ast.Node]*types.Scope),
			FileVersions: make(map[*ast.File]string),
		},
	}

	// Collect parsed files from the type check pass, capturing parse errors from
	// compiled files.
	var err error
	pkg.goFiles, err = b.parseCache.parseFiles(ctx, pkg.fset, parsego.Full, false, inputs.goFiles...)
	if err != nil {
		return nil, err
	}
	pkg.compiledGoFiles, err = b.parseCache.parseFiles(ctx, pkg.fset, parsego.Full, false, inputs.compiledGoFiles...)
	if err != nil {
		return nil, err
	}
	for _, pgf := range pkg.compiledGoFiles {
		if pgf.ParseErr != nil {
			pkg.parseErrors = append(pkg.parseErrors, pgf.ParseErr)
		}
	}

	// Use the default type information for the unsafe package.
	if inputs.pkgPath == "unsafe" {
		// Don't type check Unsafe: it's unnecessary, and doing so exposes a data
		// race to Unsafe.completed.
		pkg.types = types.Unsafe
	} else {

		if len(pkg.compiledGoFiles) == 0 {
			// No files most likely means go/packages failed.
			//
			// TODO(rfindley): in the past, we would capture go list errors in this
			// case, to present go list errors to the user. However we had no tests for
			// this behavior. It is unclear if anything better can be done here.
			return nil, fmt.Errorf("no parsed files for package %s", inputs.pkgPath)
		}

		onError := func(e error) {
			pkg.typeErrors = append(pkg.typeErrors, e.(types.Error))
		}
		cfg := b.typesConfig(ctx, inputs, imports, onError)
		check := types.NewChecker(cfg, pkg.fset, pkg.types, pkg.typesInfo)

		var files []*ast.File
		for _, cgf := range pkg.compiledGoFiles {
			files = append(files, cgf.File)
		}

		// Type checking is expensive, and we may not have encountered cancellations
		// via parsing (e.g. if we got nothing but cache hits for parsed files).
		if ctx.Err() != nil {
			return nil, ctx.Err()
		}

		// Type checking errors are handled via the config, so ignore them here.
		_ = check.Files(files) // 50us-15ms, depending on size of package

		// If the context was cancelled, we may have returned a ton of transient
		// errors to the type checker. Swallow them.
		if ctx.Err() != nil {
			return nil, ctx.Err()
		}

		// Collect imports by package path for the DependencyTypes API.
		pkg.importMap = make(map[PackagePath]*types.Package)
		var collectDeps func(*types.Package)
		collectDeps = func(p *types.Package) {
			pkgPath := PackagePath(p.Path())
			if _, ok := pkg.importMap[pkgPath]; ok {
				return
			}
			pkg.importMap[pkgPath] = p
			for _, imp := range p.Imports() {
				collectDeps(imp)
			}
		}
		collectDeps(pkg.types)

		// Work around golang/go#61561: interface instances aren't concurrency-safe
		// as they are not completed by the type checker.
		for _, inst := range pkg.typesInfo.Instances {
			if iface, _ := inst.Type.Underlying().(*types.Interface); iface != nil {
				iface.Complete()
			}
		}
	}

	// Our heuristic for whether to show type checking errors is:
	//  + If there is a parse error _in the current file_, suppress type
	//    errors in that file.
	//  + Otherwise, show type errors even in the presence of parse errors in
	//    other package files. go/types attempts to suppress follow-on errors
	//    due to bad syntax, so on balance type checking errors still provide
	//    a decent signal/noise ratio as long as the file in question parses.

	// Track URIs with parse errors so that we can suppress type errors for these
	// files.
	unparsable := map[protocol.DocumentURI]bool{}
	for _, e := range pkg.parseErrors {
		diags, err := parseErrorDiagnostics(pkg, e)
		if err != nil {
			event.Error(ctx, "unable to compute positions for parse errors", err, label.Package.Of(string(inputs.id)))
			continue
		}
		for _, diag := range diags {
			unparsable[diag.URI] = true
			pkg.diagnostics = append(pkg.diagnostics, diag)
		}
	}

	diags := typeErrorsToDiagnostics(pkg, inputs, pkg.typeErrors)
	for _, diag := range diags {
		// If the file didn't parse cleanly, it is highly likely that type
		// checking errors will be confusing or redundant. But otherwise, type
		// checking usually provides a good enough signal to include.
		if !unparsable[diag.URI] {
			pkg.diagnostics = append(pkg.diagnostics, diag)
		}
	}

	return &Package{ph.mp, ph.loadDiagnostics, pkg}, nil
}

// e.g. "go1" or "go1.2" or "go1.2.3"
var goVersionRx = regexp.MustCompile(`^go[1-9][0-9]*(?:\.(0|[1-9][0-9]*)){0,2}$`)

func (b *typeCheckBatch) typesConfig(ctx context.Context, inputs *typeCheckInputs, imports map[PackagePath]*types.Package, onError func(e error)) *types.Config {
	cfg := &types.Config{
		Sizes: inputs.sizes,
		Error: onError,
		Importer: importerFunc(func(path string) (*types.Package, error) {
			// While all of the import errors could be reported
			// based on the metadata before we start type checking,
			// reporting them via types.Importer places the errors
			// at the correct source location.
			id, ok := inputs.depsByImpPath[ImportPath(path)]
			if !ok {
				// If the import declaration is broken,
				// go list may fail to report metadata about it.
				// See TestFixImportDecl for an example.
				return nil, fmt.Errorf("missing metadata for import of %q", path)
			}
			depPH := b.getHandle(id)
			if depPH == nil {
				// e.g. missing metadata for dependencies in buildPackageHandle
				return nil, missingPkgError(inputs.id, path, inputs.viewType)
			}
			if !metadata.IsValidImport(inputs.pkgPath, depPH.mp.PkgPath, inputs.viewType != GoPackagesDriverView) {
				return nil, fmt.Errorf("invalid use of internal package %q", path)
			}
			// For syntax packages, the set of required imports is known and
			// precomputed. For import packages (checkPackageForImport), imports are
			// constructed lazily, because they may not have been needed if we could
			// have imported from export data.
			//
			// TODO(rfindley): refactor to move this logic to the callsite.
			if imports != nil {
				imp, ok := imports[depPH.mp.PkgPath]
				if !ok {
					return nil, fmt.Errorf("missing import %s", id)
				}
				return imp, nil
			}
			return b.getImportPackage(ctx, id)
		}),
	}

	if inputs.goVersion != "" {
		goVersion := "go" + inputs.goVersion
		if validGoVersion(goVersion) {
			cfg.GoVersion = goVersion
		}
	}

	// We want to type check cgo code if go/types supports it.
	// We passed typecheckCgo to go/packages when we Loaded.
	typesinternal.SetUsesCgo(cfg)
	return cfg
}

// validGoVersion reports whether goVersion is a valid Go version for go/types.
// types.NewChecker panics if GoVersion is invalid.
//
// Note that, prior to go1.21, go/types required exactly two components to the
// version number. For example, go types would panic with the Go version
// go1.21.1. validGoVersion handles this case when built with go1.20 or earlier.
func validGoVersion(goVersion string) bool {
	if !goVersionRx.MatchString(goVersion) {
		return false // malformed version string
	}

	if relVer := releaseVersion(); relVer != "" && versions.Before(versions.Lang(relVer), versions.Lang(goVersion)) {
		return false // 'go list' is too new for go/types
	}

	return true
}

// releaseVersion reports the Go language version used to compile gopls, or ""
// if it cannot be determined.
func releaseVersion() string {
	if len(build.Default.ReleaseTags) > 0 {
		v := build.Default.ReleaseTags[len(build.Default.ReleaseTags)-1]
		var dummy int
		if _, err := fmt.Sscanf(v, "go1.%d", &dummy); err == nil {
			return v
		}
	}
	return ""
}

// depsErrors creates diagnostics for each metadata error (e.g. import cycle).
// These may be attached to import declarations in the transitive source files
// of pkg, or to 'requires' declarations in the package's go.mod file.
//
// TODO(rfindley): move this to load.go
func depsErrors(ctx context.Context, snapshot *Snapshot, mp *metadata.Package) ([]*Diagnostic, error) {
	// Select packages that can't be found, and were imported in non-workspace packages.
	// Workspace packages already show their own errors.
	var relevantErrors []*packagesinternal.PackageError
	for _, depsError := range mp.DepsErrors {
		// Up to Go 1.15, the missing package was included in the stack, which
		// was presumably a bug. We want the next one up.
		directImporterIdx := len(depsError.ImportStack) - 1
		if directImporterIdx < 0 {
			continue
		}

		directImporter := depsError.ImportStack[directImporterIdx]
		if snapshot.IsWorkspacePackage(PackageID(directImporter)) {
			continue
		}
		relevantErrors = append(relevantErrors, depsError)
	}

	// Don't build the import index for nothing.
	if len(relevantErrors) == 0 {
		return nil, nil
	}

	// Subsequent checks require Go files.
	if len(mp.CompiledGoFiles) == 0 {
		return nil, nil
	}

	// Build an index of all imports in the package.
	type fileImport struct {
		cgf *parsego.File
		imp *ast.ImportSpec
	}
	allImports := map[string][]fileImport{}
	for _, uri := range mp.CompiledGoFiles {
		pgf, err := parseGoURI(ctx, snapshot, uri, parsego.Header)
		if err != nil {
			return nil, err
		}
		fset := tokeninternal.FileSetFor(pgf.Tok)
		// TODO(adonovan): modify Imports() to accept a single token.File (cgf.Tok).
		for _, group := range astutil.Imports(fset, pgf.File) {
			for _, imp := range group {
				if imp.Path == nil {
					continue
				}
				path := strings.Trim(imp.Path.Value, `"`)
				allImports[path] = append(allImports[path], fileImport{pgf, imp})
			}
		}
	}

	// Apply a diagnostic to any import involved in the error, stopping once
	// we reach the workspace.
	var errors []*Diagnostic
	for _, depErr := range relevantErrors {
		for i := len(depErr.ImportStack) - 1; i >= 0; i-- {
			item := depErr.ImportStack[i]
			if snapshot.IsWorkspacePackage(PackageID(item)) {
				break
			}

			for _, imp := range allImports[item] {
				rng, err := imp.cgf.NodeRange(imp.imp)
				if err != nil {
					return nil, err
				}
				diag := &Diagnostic{
					URI:            imp.cgf.URI,
					Range:          rng,
					Severity:       protocol.SeverityError,
					Source:         TypeError,
					Message:        fmt.Sprintf("error while importing %v: %v", item, depErr.Err),
					SuggestedFixes: goGetQuickFixes(mp.Module != nil, imp.cgf.URI, item),
				}
				if !bundleLazyFixes(diag) {
					bug.Reportf("failed to bundle fixes for diagnostic %q", diag.Message)
				}
				errors = append(errors, diag)
			}
		}
	}

	modFile, err := findRootPattern(ctx, mp.CompiledGoFiles[0].Dir(), "go.mod", snapshot)
	if err != nil {
		return nil, err
	}
	pm, err := parseModURI(ctx, snapshot, modFile)
	if err != nil {
		return nil, err
	}

	// Add a diagnostic to the module that contained the lowest-level import of
	// the missing package.
	for _, depErr := range relevantErrors {
		for i := len(depErr.ImportStack) - 1; i >= 0; i-- {
			item := depErr.ImportStack[i]
			mp := snapshot.Metadata(PackageID(item))
			if mp == nil || mp.Module == nil {
				continue
			}
			modVer := module.Version{Path: mp.Module.Path, Version: mp.Module.Version}
			reference := findModuleReference(pm.File, modVer)
			if reference == nil {
				continue
			}
			rng, err := pm.Mapper.OffsetRange(reference.Start.Byte, reference.End.Byte)
			if err != nil {
				return nil, err
			}
			diag := &Diagnostic{
				URI:            pm.URI,
				Range:          rng,
				Severity:       protocol.SeverityError,
				Source:         TypeError,
				Message:        fmt.Sprintf("error while importing %v: %v", item, depErr.Err),
				SuggestedFixes: goGetQuickFixes(true, pm.URI, item),
			}
			if !bundleLazyFixes(diag) {
				bug.Reportf("failed to bundle fixes for diagnostic %q", diag.Message)
			}
			errors = append(errors, diag)
			break
		}
	}
	return errors, nil
}

// missingPkgError returns an error message for a missing package that varies
// based on the user's workspace mode.
func missingPkgError(from PackageID, pkgPath string, viewType ViewType) error {
	switch viewType {
	case GoModView, GoWorkView:
		if metadata.IsCommandLineArguments(from) {
			return fmt.Errorf("current file is not included in a workspace module")
		} else {
			// Previously, we would present the initialization error here.
			return fmt.Errorf("no required module provides package %q", pkgPath)
		}
	case AdHocView:
		return fmt.Errorf("cannot find package %q in GOROOT", pkgPath)
	case GoPackagesDriverView:
		return fmt.Errorf("go/packages driver could not load %q", pkgPath)
	case GOPATHView:
		return fmt.Errorf("cannot find package %q in GOROOT or GOPATH", pkgPath)
	default:
		return fmt.Errorf("unable to load package")
	}
}

// typeErrorsToDiagnostics translates a slice of types.Errors into a slice of
// Diagnostics.
//
// In addition to simply mapping data such as position information and error
// codes, this function interprets related go/types "continuation" errors as
// protocol.DiagnosticRelatedInformation. Continuation errors are go/types
// errors whose messages starts with "\t". By convention, these errors relate
// to the previous error in the errs slice (such as if they were printed in
// sequence to a terminal).
//
// Fields in typeCheckInputs may affect the resulting diagnostics.
func typeErrorsToDiagnostics(pkg *syntaxPackage, inputs *typeCheckInputs, errs []types.Error) []*Diagnostic {
	var result []*Diagnostic

	// batch records diagnostics for a set of related types.Errors.
	// (related[0] is the primary error.)
	batch := func(related []types.Error) {
		var diags []*Diagnostic
		for i, e := range related {
			code, start, end, ok := typesinternal.ErrorCodeStartEnd(e)
			if !ok || !start.IsValid() || !end.IsValid() {
				start, end = e.Pos, e.Pos
				code = 0
			}
			if !start.IsValid() {
				// Type checker errors may be missing position information if they
				// relate to synthetic syntax, such as if the file were fixed. In that
				// case, we should have a parse error anyway, so skipping the type
				// checker error is likely benign.
				//
				// TODO(golang/go#64335): we should eventually verify that all type
				// checked syntax has valid positions, and promote this skip to a bug
				// report.
				continue
			}

			// Invariant: both start and end are IsValid.
			if !end.IsValid() {
				panic("end is invalid")
			}

			posn := safetoken.StartPosition(e.Fset, start)
			if !posn.IsValid() {
				// All valid positions produced by the type checker should described by
				// its fileset, yet since type checker errors are associated with
				// positions in the AST, and AST nodes can overflow the file
				// (golang/go#48300), we can't rely on this.
				//
				// We should fix the parser, but in the meantime type errors are not
				// significant if there are parse errors, so we can safely ignore this
				// case.
				if len(pkg.parseErrors) == 0 {
					bug.Reportf("internal error: type checker error %q outside its Fset", e)
				}
				continue
			}
			pgf, err := pkg.File(protocol.URIFromPath(posn.Filename))
			if err != nil {
				// Sometimes type-checker errors refer to positions in other packages,
				// such as when a declaration duplicates a dot-imported name.
				//
				// In these cases, we don't want to report an error in the other
				// package (the message would be rather confusing), but we do want to
				// report an error in the current package (golang/go#59005).
				if i == 0 {
					if pkg.hasFixedFiles() {
						bug.Reportf("internal error: could not locate file for primary type checker error %v: %v (fixed files)", e, err)
					} else {
						bug.Reportf("internal error: could not locate file for primary type checker error %v: %v", e, err)
					}
				}
				continue
			}

			// debugging golang/go#65960
			//
			// At this point, we know 'start' IsValid, and
			// StartPosition(start) worked (with e.Fset).
			//
			// If the asserted condition is true, 'start'
			// is also in range for pgf.Tok, which means
			// the PosRange failure must be caused by 'end'.
			if pgf.Tok != e.Fset.File(start) {
				if pkg.hasFixedFiles() {
					bug.Reportf("internal error: inconsistent token.Files for pos (fixed files)")
				} else {
					bug.Reportf("internal error: inconsistent token.Files for pos")
				}
			}

			if end == start {
				// Expand the end position to a more meaningful span.
				//
				// TODO(adonovan): It is the type checker's responsibility
				// to ensure that (start, end) are meaningful; see #71803.
				end = typeErrorEndPos(pgf.Tok, pgf.Src, start)

				// debugging golang/go#65960
				if _, err := safetoken.Offset(pgf.Tok, end); err != nil {
					if pkg.hasFixedFiles() {
						bug.Reportf("TypeErrorEndPos returned invalid end: %v (fixed files)", err)
					} else {
						bug.Reportf("TypeErrorEndPos returned invalid end: %v", err)
					}
				}
			} else {
				// TODO(adonovan): check File(start)==File(end).

				// debugging golang/go#65960
				if _, err := safetoken.Offset(pgf.Tok, end); err != nil {
					if pkg.hasFixedFiles() {
						bug.Reportf("ErrorCodeStartEnd returned invalid end: %v (fixed files)", err)
					} else {
						bug.Reportf("ErrorCodeStartEnd returned invalid end: %v", err)
					}
				}
			}

			rng, err := pgf.Mapper.PosRange(pgf.Tok, start, end)
			if err != nil {
				bug.Reportf("internal error: could not compute pos to range for %v: %v", e, err)
				continue
			}
			msg := related[0].Msg // primary
			if i > 0 {
				if inputs.supportsRelatedInformation {
					msg += " (see details)"
				} else {
					msg += fmt.Sprintf(" (this error: %v)", e.Msg)
				}
			}
			diag := &Diagnostic{
				URI:      pgf.URI,
				Range:    rng,
				Severity: protocol.SeverityError,
				Source:   TypeError,
				Message:  msg,
			}
			if code != 0 {
				diag.Code = code.String()
				diag.CodeHref = typesCodeHref(inputs.linkTarget, code)
			}
			if code == typesinternal.UnusedVar || code == typesinternal.UnusedImport {
				diag.Tags = append(diag.Tags, protocol.Unnecessary)
			}
			if match := importErrorRe.FindStringSubmatch(e.Msg); match != nil {
				diag.SuggestedFixes = append(diag.SuggestedFixes, goGetQuickFixes(inputs.viewType.usesModules(), pgf.URI, match[1])...)
			}
			if match := unsupportedFeatureRe.FindStringSubmatch(e.Msg); match != nil {
				diag.SuggestedFixes = append(diag.SuggestedFixes, editGoDirectiveQuickFix(inputs.viewType.usesModules(), pgf.URI, match[1])...)
			}

			// Link up related information. For the primary error, all related errors
			// are treated as related information. For secondary errors, only the
			// primary is related.
			//
			// This is because go/types assumes that errors are read top-down, such as
			// in the cycle error "A refers to...". The structure of the secondary
			// error set likely only makes sense for the primary error.
			//
			// NOTE: len(diags) == 0 if the primary diagnostic has invalid positions.
			// See also golang/go#66731.
			if i > 0 && len(diags) > 0 {
				primary := diags[0]
				primary.Related = append(primary.Related, protocol.DiagnosticRelatedInformation{
					Location: diag.URI.Location(diag.Range),
					Message:  related[i].Msg, // use the unmodified secondary error for related errors.
				})
				diag.Related = []protocol.DiagnosticRelatedInformation{{
					Location: primary.URI.Location(primary.Range),
				}}
			}
			diags = append(diags, diag)
		}
		result = append(result, diags...)
	}

	// Process batches of related errors.
	for len(errs) > 0 {
		related := []types.Error{errs[0]}
		for i := 1; i < len(errs); i++ {
			spl := errs[i]
			if len(spl.Msg) == 0 || spl.Msg[0] != '\t' {
				break
			}
			spl.Msg = spl.Msg[len("\t"):]
			related = append(related, spl)
		}
		batch(related)
		errs = errs[len(related):]
	}

	return result
}

// This heuristic is ill-defined.
func typeErrorEndPos(tokFile *token.File, src []byte, start token.Pos) token.Pos {
	// Get the end position for the type error.
	offset, err := safetoken.Offset(tokFile, start)
	if err != nil || offset > len(src) {
		return start
	}
	src = src[offset:]

	// Attempt to find a reasonable end position for the type error.
	//
	// TODO(rfindley): the heuristic implemented here is unclear. It looks like
	// it seeks the end of the primary operand starting at start, but that is not
	// quite implemented (for example, given a func literal this heuristic will
	// return the range of the func keyword).
	//
	// We should formalize this heuristic, or deprecate it by finally proposing
	// to add end position to all type checker errors.
	//
	// Nevertheless, ensure that the end position at least spans the current
	// token at the cursor (this was golang/go#69505).
	end := start
	{
		var s scanner.Scanner
		fset := token.NewFileSet()
		f := fset.AddFile("", fset.Base(), len(src))
		s.Init(f, src, nil /* no error handler */, scanner.ScanComments)
		pos, tok, lit := s.Scan()
		if tok != token.SEMICOLON {
			if off, err := safetoken.Offset(f, pos); err == nil {
				off += len(lit)
				src = src[off:]
				end += token.Pos(off)
			}
		}
	}

	// Look for bytes that might terminate the current operand. See note above:
	// this is imprecise.
	if width := bytes.IndexAny(src, " \n,():;[]+-*/"); width > 0 {
		end += token.Pos(width)
	}
	return end
}

// An importFunc is an implementation of the single-method
// types.Importer interface based on a function value.
type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }


================================================
FILE: gopls/internal/cache/constraints.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"go/ast"
	"go/build/constraint"
	"go/parser"
	"go/token"
	"slices"
)

// isStandaloneFile reports whether a file with the given contents should be
// considered a 'standalone main file', meaning a package that consists of only
// a single file.
func isStandaloneFile(src []byte, standaloneTags []string) bool {
	f, err := parser.ParseFile(token.NewFileSet(), "", src, parser.PackageClauseOnly|parser.ParseComments)
	if err != nil {
		return false
	}

	if f.Name == nil || f.Name.Name != "main" {
		return false
	}

	found := false
	walkConstraints(f, func(c constraint.Expr) bool {
		if tag, ok := c.(*constraint.TagExpr); ok {
			if slices.Contains(standaloneTags, tag.Tag) {
				found = true
				return false
			}
		}
		return true
	})

	return found
}

// walkConstraints calls f for each constraint expression in the file, until
// all constraints are exhausted or f returns false.
func walkConstraints(file *ast.File, f func(constraint.Expr) bool) {
	for _, cg := range file.Comments {
		// Even with PackageClauseOnly the parser consumes the semicolon following
		// the package clause, so we must guard against comments that come after
		// the package name.
		if cg.Pos() > file.Name.Pos() {
			continue
		}
		for _, comment := range cg.List {
			if c, err := constraint.Parse(comment.Text); err == nil {
				if !f(c) {
					return
				}
			}
		}
	}
}


================================================
FILE: gopls/internal/cache/constraints_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"testing"
)

func TestIsStandaloneFile(t *testing.T) {
	tests := []struct {
		desc           string
		contents       string
		standaloneTags []string
		want           bool
	}{
		{
			"new syntax",
			"//go:build ignore\n\npackage main\n",
			[]string{"ignore"},
			true,
		},
		{
			"legacy syntax",
			"// +build ignore\n\npackage main\n",
			[]string{"ignore"},
			true,
		},
		{
			"multiple tags",
			"//go:build ignore\n\npackage main\n",
			[]string{"exclude", "ignore"},
			true,
		},
		{
			"invalid tag",
			"// +build ignore\n\npackage main\n",
			[]string{"script"},
			false,
		},
		{
			"non-main package",
			"//go:build ignore\n\npackage p\n",
			[]string{"ignore"},
			false,
		},
		{
			"alternate tag",
			"// +build script\n\npackage main\n",
			[]string{"script"},
			true,
		},
		{
			"both syntax",
			"//go:build ignore\n// +build ignore\n\npackage main\n",
			[]string{"ignore"},
			true,
		},
		{
			"after comments",
			"// A non-directive comment\n//go:build ignore\n\npackage main\n",
			[]string{"ignore"},
			true,
		},
		{
			"after package decl",
			"package main //go:build ignore\n",
			[]string{"ignore"},
			false,
		},
		{
			"on line after package decl",
			"package main\n\n//go:build ignore\n",
			[]string{"ignore"},
			false,
		},
		{
			"combined with other expressions",
			"\n\n//go:build ignore || darwin\n\npackage main\n",
			[]string{"ignore"},
			false,
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			if got := isStandaloneFile([]byte(test.contents), test.standaloneTags); got != test.want {
				t.Errorf("isStandaloneFile(%q, %v) = %t, want %t", test.contents, test.standaloneTags, got, test.want)
			}
		})
	}
}

func TestVersionRegexp(t *testing.T) {
	// good
	for _, s := range []string{
		"go1",
		"go1.2",
		"go1.2.3",
		"go1.0.33",
	} {
		if !goVersionRx.MatchString(s) {
			t.Errorf("Valid Go version %q does not match the regexp", s)
		}
	}

	// bad
	for _, s := range []string{
		"go",          // missing numbers
		"go0",         // Go starts at 1
		"go01",        // leading zero
		"go1.π",       // non-decimal
		"go1.-1",      // negative
		"go1.02.3",    // leading zero
		"go1.2.3.4",   // too many segments
		"go1.2.3-pre", // textual suffix
	} {
		if goVersionRx.MatchString(s) {
			t.Errorf("Invalid Go version %q unexpectedly matches the regexp", s)
		}
	}
}


================================================
FILE: gopls/internal/cache/debug.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

// assert panics with the given msg if cond is not true.
func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}


================================================
FILE: gopls/internal/cache/diagnostics.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"crypto/sha256"
	"encoding/json"
	"fmt"
	"strings"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
)

// A InitializationError is an error that causes snapshot initialization to fail.
// It is either the error returned from go/packages.Load, or an error parsing a
// workspace go.work or go.mod file.
//
// Such an error generally indicates that the View is malformed, and will never
// be usable.
type InitializationError struct {
	// MainError is the primary error. Must be non-nil.
	MainError error

	// Diagnostics contains any supplemental (structured) diagnostics extracted
	// from the load error.
	Diagnostics map[protocol.DocumentURI][]*Diagnostic
}

func byURI(d *Diagnostic) protocol.DocumentURI { return d.URI } // For use in maps.Group.

// A Diagnostic corresponds to an LSP Diagnostic.
// https://microsoft.github.io/language-server-protocol/specification#diagnostic
//
// It is (effectively) gob-serializable; see {encode,decode}Diagnostics.
type Diagnostic struct {
	URI      protocol.DocumentURI // of diagnosed file (not diagnostic documentation)
	Range    protocol.Range
	Severity protocol.DiagnosticSeverity
	Code     string // analysis.Diagnostic.Category (or "default" if empty) or hidden go/types error code
	CodeHref string

	// Source is a human-readable description of the source of the error.
	// Diagnostics generated by an analysis.Analyzer set it to Analyzer.Name.
	Source DiagnosticSource

	Message string

	Tags    []protocol.DiagnosticTag
	Related []protocol.DiagnosticRelatedInformation

	// Fields below are used internally to generate lazy fixes. They aren't
	// part of the LSP spec and historically didn't leave the server.
	//
	// Update(2023-05): version 3.16 of the LSP spec included support for the
	// Diagnostic.data field, which holds arbitrary data preserved in the
	// diagnostic for codeAction requests. This field allows bundling additional
	// information for lazy fixes, and gopls can (and should) use this
	// information to avoid re-evaluating diagnostics in code-action handlers.
	//
	// In order to stage this transition incrementally, the 'BundledFixes' field
	// may store a 'bundled' (=json-serialized) form of the associated
	// SuggestedFixes. Not all diagnostics have their fixes bundled.
	BundledFixes   *json.RawMessage
	SuggestedFixes []SuggestedFix
}

func (d *Diagnostic) String() string {
	return fmt.Sprintf("%v: %s", d.Range, d.Message)
}

// Hash computes a hash to identify the diagnostic.
// The hash is for deduplicating within a file, so does not incorporate d.URI.
func (d *Diagnostic) Hash() file.Hash {
	h := sha256.New()
	for _, t := range d.Tags {
		fmt.Fprintf(h, "tag: %s\n", t)
	}
	for _, r := range d.Related {
		fmt.Fprintf(h, "related: %s %s %s\n", r.Location.URI, r.Message, r.Location.Range)
	}
	fmt.Fprintf(h, "code: %s\n", d.Code)
	fmt.Fprintf(h, "codeHref: %s\n", d.CodeHref)
	fmt.Fprintf(h, "message: %s\n", d.Message)
	fmt.Fprintf(h, "range: %s\n", d.Range)
	fmt.Fprintf(h, "severity: %s\n", d.Severity)
	fmt.Fprintf(h, "source: %s\n", d.Source)
	if d.BundledFixes != nil {
		fmt.Fprintf(h, "fixes: %s\n", *d.BundledFixes)
	}
	var hash [sha256.Size]byte
	h.Sum(hash[:0])
	return hash
}

func ToProtocolDiagnostics(diagnostics ...*Diagnostic) []protocol.Diagnostic {
	// TODO(rfindley): support bundling edits, and bundle all suggested fixes here.
	// (see cache.bundleLazyFixes).

	reports := []protocol.Diagnostic{}
	for _, diag := range diagnostics {
		pdiag := protocol.Diagnostic{
			// diag.Message might start with \n or \t
			Message:            strings.TrimSpace(diag.Message),
			Range:              diag.Range,
			Severity:           diag.Severity,
			Source:             string(diag.Source),
			Tags:               protocol.NonNilSlice(diag.Tags),
			RelatedInformation: diag.Related,
			Data:               diag.BundledFixes,
		}
		if diag.Code != "" {
			pdiag.Code = diag.Code
		}
		if diag.CodeHref != "" {
			pdiag.CodeDescription = &protocol.CodeDescription{Href: diag.CodeHref}
		}
		reports = append(reports, pdiag)
	}
	return reports
}

// A DiagnosticSource identifies the source of a diagnostic.
//
// Its value may be one of the distinguished string values below, or
// the Name of an [analysis.Analyzer].
type DiagnosticSource string

const (
	UnknownError           DiagnosticSource = "<Unknown source>"
	ListError              DiagnosticSource = "go list"
	ParseError             DiagnosticSource = "syntax"
	TypeError              DiagnosticSource = "compiler"
	ModTidyError           DiagnosticSource = "go mod tidy"
	CompilerOptDetailsInfo DiagnosticSource = "optimizer details" // cmd/compile -json=0,dir
	UpgradeNotification    DiagnosticSource = "upgrade available"
	Vulncheck              DiagnosticSource = "vulncheck imports"
	Govulncheck            DiagnosticSource = "govulncheck"
	TemplateError          DiagnosticSource = "template"
	WorkFileError          DiagnosticSource = "go.work file"
)

// A SuggestedFix represents a suggested fix (for a diagnostic)
// produced by analysis, in protocol form.
//
// The fixes are reported to the client as a set of code actions in
// response to a CodeAction query for a set of diagnostics. Multiple
// SuggestedFixes may be produced for the same logical fix, varying
// only in ActionKind. For example, a fix may be both a Refactor
// (which should appear on the refactoring menu) and a SourceFixAll (a
// clear fix that can be safely applied without explicit consent).
type SuggestedFix struct {
	Title      string
	Edits      map[protocol.DocumentURI][]protocol.TextEdit
	Command    *protocol.Command
	ActionKind protocol.CodeActionKind
}

// SuggestedFixFromCommand returns a suggested fix to run the given command.
func SuggestedFixFromCommand(cmd *protocol.Command, kind protocol.CodeActionKind) SuggestedFix {
	return SuggestedFix{
		Title:      cmd.Title,
		Command:    cmd,
		ActionKind: kind,
	}
}

// lazyFixesJSON is a JSON-serializable list of code actions (arising
// from "lazy" SuggestedFixes with no Edits) to be saved in the
// protocol.Diagnostic.Data field. Computation of the edits is thus
// deferred until the action's command is invoked.
type lazyFixesJSON struct {
	// TODO(rfindley): pack some sort of identifier here for later
	// lookup/validation?
	Actions []protocol.CodeAction
}

// bundleLazyFixes attempts to bundle sd.SuggestedFixes into the
// sd.BundledFixes field, so that it can be round-tripped through the client.
// It returns false if the fixes cannot be bundled.
func bundleLazyFixes(sd *Diagnostic) bool {
	if len(sd.SuggestedFixes) == 0 {
		return true
	}
	var actions []protocol.CodeAction
	for _, fix := range sd.SuggestedFixes {
		if fix.Edits != nil {
			// For now, we only support bundled code actions that execute commands.
			//
			// In order to cleanly support bundled edits, we'd have to guarantee that
			// the edits were generated on the current snapshot. But this naively
			// implies that every fix would have to include a snapshot ID, which
			// would require us to republish all diagnostics on each new snapshot.
			//
			// TODO(rfindley): in order to avoid this additional chatter, we'd need
			// to build some sort of registry or other mechanism on the snapshot to
			// check whether a diagnostic is still valid.
			return false
		}
		action := protocol.CodeAction{
			Title:   fix.Title,
			Kind:    fix.ActionKind,
			Command: fix.Command,
		}
		actions = append(actions, action)
	}
	fixes := lazyFixesJSON{
		Actions: actions,
	}
	data, err := json.Marshal(fixes)
	if err != nil {
		bug.Reportf("marshalling lazy fixes: %v", err)
		return false
	}
	msg := json.RawMessage(data)
	sd.BundledFixes = &msg
	return true
}

// BundledLazyFixes extracts any bundled codeActions from the
// diag.Data field.
func BundledLazyFixes(diag protocol.Diagnostic) ([]protocol.CodeAction, error) {
	var fix lazyFixesJSON
	if diag.Data != nil {
		err := protocol.UnmarshalJSON(*diag.Data, &fix)
		if err != nil {
			return nil, fmt.Errorf("unmarshalling fix from diagnostic data: %v", err)
		}
	}

	var actions []protocol.CodeAction
	for _, action := range fix.Actions {
		// See bundleLazyFixes: for now we only support bundling commands.
		if action.Edit != nil {
			return nil, fmt.Errorf("bundled fix %q includes workspace edits", action.Title)
		}
		// associate the action with the incoming diagnostic
		// (Note that this does not mutate the fix.Fixes slice).
		action.Diagnostics = []protocol.Diagnostic{diag}
		actions = append(actions, action)
	}

	return actions, nil
}


================================================
FILE: gopls/internal/cache/errors.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

// This file defines routines to convert diagnostics from go list, go
// get, go/packages, parsing, type checking, and analysis into
// golang.Diagnostic form, and suggesting quick fixes.

import (
	"context"
	"fmt"
	"go/parser"
	"go/scanner"
	"go/token"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/typesinternal"
)

// goPackagesErrorDiagnostics translates the given go/packages Error into a
// diagnostic, using the provided metadata and filesource.
//
// The slice of diagnostics may be empty.
func goPackagesErrorDiagnostics(ctx context.Context, e packages.Error, mp *metadata.Package, fs file.Source) ([]*Diagnostic, error) {
	if diag, err := parseGoListImportCycleError(ctx, e, mp, fs); err != nil {
		return nil, err
	} else if diag != nil {
		return []*Diagnostic{diag}, nil
	}

	// Parse error location and attempt to convert to protocol form.
	loc, err := func() (protocol.Location, error) {
		filename, line, col8 := parseGoListError(e, mp.LoadDir)
		uri := protocol.URIFromPath(filename)

		fh, err := fs.ReadFile(ctx, uri)
		if err != nil {
			return protocol.Location{}, err
		}
		content, err := fh.Content()
		if err != nil {
			return protocol.Location{}, err
		}
		mapper := protocol.NewMapper(uri, content)
		posn, err := mapper.LineCol8Position(line, col8)
		if err != nil {
			return protocol.Location{}, err
		}
		return protocol.Location{
			URI: uri,
			Range: protocol.Range{
				Start: posn,
				End:   posn,
			},
		}, nil
	}()

	// TODO(rfindley): in some cases the go command outputs invalid spans, for
	// example (from TestGoListErrors):
	//
	//   package a
	//   import
	//
	// In this case, the go command will complain about a.go:2:8, which is after
	// the trailing newline but still considered to be on the second line, most
	// likely because *token.File lacks information about newline termination.
	//
	// We could do better here by handling that case.
	if err != nil {
		// Unable to parse a valid position.
		// Apply the error to all files to be safe.
		var diags []*Diagnostic
		for _, uri := range mp.CompiledGoFiles {
			diags = append(diags, &Diagnostic{
				URI:      uri,
				Severity: protocol.SeverityError,
				Source:   ListError,
				Message:  e.Msg,
			})
		}
		return diags, nil
	}
	return []*Diagnostic{{
		URI:      loc.URI,
		Range:    loc.Range,
		Severity: protocol.SeverityError,
		Source:   ListError,
		Message:  e.Msg,
	}}, nil
}

func parseErrorDiagnostics(pkg *syntaxPackage, errList scanner.ErrorList) ([]*Diagnostic, error) {
	// The first parser error is likely the root cause of the problem.
	if errList.Len() <= 0 {
		return nil, fmt.Errorf("no errors in %v", errList)
	}
	e := errList[0]
	pgf, err := pkg.File(protocol.URIFromPath(e.Pos.Filename))
	if err != nil {
		return nil, err
	}
	rng, err := pgf.Mapper.OffsetRange(e.Pos.Offset, e.Pos.Offset)
	if err != nil {
		return nil, err
	}
	return []*Diagnostic{{
		URI:      pgf.URI,
		Range:    rng,
		Severity: protocol.SeverityError,
		Source:   ParseError,
		Message:  e.Msg,
	}}, nil
}

var importErrorRe = regexp.MustCompile(`could not import ([^\s]+)`)
var unsupportedFeatureRe = regexp.MustCompile(`.*require.* go(\d+\.\d+) or later`)

func goGetQuickFixes(haveModule bool, uri protocol.DocumentURI, pkg string) []SuggestedFix {
	// Go get only supports module mode for now.
	if !haveModule {
		return nil
	}
	title := fmt.Sprintf("go get package %v", pkg)
	cmd := command.NewGoGetPackageCommand(title, command.GoGetPackageArgs{
		URI:        uri,
		AddRequire: true,
		Pkg:        pkg,
	})
	return []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)}
}

func editGoDirectiveQuickFix(haveModule bool, uri protocol.DocumentURI, version string) []SuggestedFix {
	// Go mod edit only supports module mode.
	if !haveModule {
		return nil
	}
	title := fmt.Sprintf("go mod edit -go=%s", version)
	cmd := command.NewEditGoDirectiveCommand(title, command.EditGoDirectiveArgs{
		URI:     uri,
		Version: version,
	})
	return []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)}
}

// encodeDiagnostics gob-encodes the given diagnostics.
func encodeDiagnostics(srcDiags []*Diagnostic) []byte {
	var gobDiags []gobDiagnostic
	for _, srcDiag := range srcDiags {
		var gobFixes []gobSuggestedFix
		for _, srcFix := range srcDiag.SuggestedFixes {
			gobFix := gobSuggestedFix{
				Message:    srcFix.Title,
				ActionKind: srcFix.ActionKind,
			}
			for uri, srcEdits := range srcFix.Edits {
				for _, srcEdit := range srcEdits {
					gobFix.TextEdits = append(gobFix.TextEdits, gobTextEdit{
						Location: uri.Location(srcEdit.Range),
						NewText:  []byte(srcEdit.NewText),
					})
				}
			}
			if srcCmd := srcFix.Command; srcCmd != nil {
				gobFix.Command = &gobCommand{
					Title:     srcCmd.Title,
					Command:   srcCmd.Command,
					Arguments: srcCmd.Arguments,
				}
			}
			gobFixes = append(gobFixes, gobFix)
		}
		var gobRelated []gobRelatedInformation
		for _, srcRel := range srcDiag.Related {
			gobRel := gobRelatedInformation(srcRel)
			gobRelated = append(gobRelated, gobRel)
		}
		gobDiag := gobDiagnostic{
			Location:       srcDiag.URI.Location(srcDiag.Range),
			Severity:       srcDiag.Severity,
			Code:           srcDiag.Code,
			CodeHref:       srcDiag.CodeHref,
			Source:         string(srcDiag.Source),
			Message:        srcDiag.Message,
			SuggestedFixes: gobFixes,
			Related:        gobRelated,
			Tags:           srcDiag.Tags,
		}
		gobDiags = append(gobDiags, gobDiag)
	}
	return diagnosticsCodec.Encode(gobDiags)
}

// decodeDiagnostics decodes the given gob-encoded diagnostics.
func decodeDiagnostics(data []byte) []*Diagnostic {
	var gobDiags []gobDiagnostic
	diagnosticsCodec.Decode(data, &gobDiags)
	var srcDiags []*Diagnostic
	for _, gobDiag := range gobDiags {
		var srcFixes []SuggestedFix
		for _, gobFix := range gobDiag.SuggestedFixes {
			srcFix := SuggestedFix{
				Title:      gobFix.Message,
				ActionKind: gobFix.ActionKind,
			}
			for _, gobEdit := range gobFix.TextEdits {
				if srcFix.Edits == nil {
					srcFix.Edits = make(map[protocol.DocumentURI][]protocol.TextEdit)
				}
				srcEdit := protocol.TextEdit{
					Range:   gobEdit.Location.Range,
					NewText: string(gobEdit.NewText),
				}
				uri := gobEdit.Location.URI
				srcFix.Edits[uri] = append(srcFix.Edits[uri], srcEdit)
			}
			if gobCmd := gobFix.Command; gobCmd != nil {
				srcFix.Command = &protocol.Command{
					Title:     gobCmd.Title,
					Command:   gobCmd.Command,
					Arguments: gobCmd.Arguments,
				}
			}
			srcFixes = append(srcFixes, srcFix)
		}
		var srcRelated []protocol.DiagnosticRelatedInformation
		for _, gobRel := range gobDiag.Related {
			srcRel := protocol.DiagnosticRelatedInformation(gobRel)
			srcRelated = append(srcRelated, srcRel)
		}
		srcDiag := &Diagnostic{
			URI:            gobDiag.Location.URI,
			Range:          gobDiag.Location.Range,
			Severity:       gobDiag.Severity,
			Code:           gobDiag.Code,
			CodeHref:       gobDiag.CodeHref,
			Source:         DiagnosticSource(gobDiag.Source),
			Message:        gobDiag.Message,
			Tags:           gobDiag.Tags,
			Related:        srcRelated,
			SuggestedFixes: srcFixes,
		}
		srcDiags = append(srcDiags, srcDiag)
	}
	return srcDiags
}

// toSourceDiagnostic converts a gobDiagnostic to "source" form.
func toSourceDiagnostic(srcAnalyzer *settings.Analyzer, gobDiag *gobDiagnostic) *Diagnostic {
	var related []protocol.DiagnosticRelatedInformation
	for _, gobRelated := range gobDiag.Related {
		related = append(related, protocol.DiagnosticRelatedInformation(gobRelated))
	}

	diag := &Diagnostic{
		URI:      gobDiag.Location.URI,
		Range:    gobDiag.Location.Range,
		Severity: srcAnalyzer.Severity(),
		Code:     gobDiag.Code,
		CodeHref: gobDiag.CodeHref,
		Source:   DiagnosticSource(gobDiag.Source),
		Message:  gobDiag.Message,
		Related:  related,
		Tags:     srcAnalyzer.Tags(),
	}

	// We cross the set of fixes (whether edit- or command-based)
	// with the set of kinds, as a single fix may represent more
	// than one kind of action (e.g. refactor, quickfix, fixall),
	// each corresponding to a distinct client UI element
	// or operation.
	kinds := srcAnalyzer.ActionKinds()
	if len(kinds) == 0 {
		kinds = []protocol.CodeActionKind{protocol.QuickFix}
	}

	var fixes []SuggestedFix
	for _, fix := range gobDiag.SuggestedFixes {
		if len(fix.TextEdits) > 0 {
			// Accumulate edit-based fixes supplied by the diagnostic itself.
			edits := make(map[protocol.DocumentURI][]protocol.TextEdit)
			for _, e := range fix.TextEdits {
				uri := e.Location.URI
				edits[uri] = append(edits[uri], protocol.TextEdit{
					Range:   e.Location.Range,
					NewText: string(e.NewText),
				})
			}
			for _, kind := range kinds {
				fixes = append(fixes, SuggestedFix{
					Title:      fix.Message,
					Edits:      edits,
					ActionKind: kind,
				})
			}

		} else {
			// Accumulate command-based fixes, whose edits
			// are not provided by the analyzer but are computed on demand
			// by logic "adjacent to" the analyzer.
			//
			// The analysis.Diagnostic.Category is used as the fix name.
			cmd := command.NewApplyFixCommand(fix.Message, command.ApplyFixArgs{
				Fix:      diag.Code,
				Location: gobDiag.Location,
			})
			for _, kind := range kinds {
				fixes = append(fixes, SuggestedFixFromCommand(cmd, kind))
			}

			// Ensure that the analyzer specifies a category for all its no-edit fixes.
			// This is asserted by analysistest.RunWithSuggestedFixes, but there
			// may be gaps in test coverage.
			if diag.Code == "" || diag.Code == "default" {
				bug.Reportf("missing Diagnostic.Code: %#v", *diag)
			}
		}
	}
	diag.SuggestedFixes = fixes

	// If the fixes only delete code, assume that the diagnostic is reporting dead code.
	if onlyDeletions(diag.SuggestedFixes) {
		diag.Tags = append(diag.Tags, protocol.Unnecessary)
	}
	return diag
}

// onlyDeletions returns true if fixes is non-empty and all of the suggested
// fixes are deletions.
func onlyDeletions(fixes []SuggestedFix) bool {
	for _, fix := range fixes {
		if fix.Command != nil {
			return false
		}
		for _, edits := range fix.Edits {
			for _, edit := range edits {
				if edit.NewText != "" {
					return false
				}
				if protocol.ComparePosition(edit.Range.Start, edit.Range.End) == 0 {
					return false
				}
			}
		}
	}
	return len(fixes) > 0
}

func typesCodeHref(linkTarget string, code typesinternal.ErrorCode) string {
	return BuildLink(linkTarget, "golang.org/x/tools/internal/typesinternal", code.String())
}

// BuildLink constructs a URL with the given target, path, and anchor.
func BuildLink(target, path, anchor string) protocol.URI {
	link := fmt.Sprintf("https://%s/%s", target, path)
	if anchor == "" {
		return link
	}
	return link + "#" + anchor
}

func parseGoListError(e packages.Error, dir string) (filename string, line, col8 int) {
	input := e.Pos
	if input == "" {
		// No position. Attempt to parse one out of a
		// go list error of the form "file:line:col:
		// message" by stripping off the message.
		input = strings.TrimSpace(e.Msg)
		if i := strings.Index(input, ": "); i >= 0 {
			input = input[:i]
		}
	}

	filename, line, col8 = splitFileLineCol(input)
	if !filepath.IsAbs(filename) {
		filename = filepath.Join(dir, filename)
	}
	return filename, line, col8
}

// splitFileLineCol splits s into "filename:line:col",
// where line and col consist of decimal digits.
func splitFileLineCol(s string) (file string, line, col8 int) {
	// Beware that the filename may contain colon on Windows.

	// stripColonDigits removes a ":%d" suffix, if any.
	stripColonDigits := func(s string) (rest string, num int) {
		if i := strings.LastIndex(s, ":"); i >= 0 {
			if v, err := strconv.ParseInt(s[i+1:], 10, 32); err == nil {
				return s[:i], int(v)
			}
		}
		return s, -1
	}

	// strip col ":%d"
	s, n1 := stripColonDigits(s)
	if n1 < 0 {
		return s, 1, 1 // "filename"
	}

	// strip line ":%d"
	s, n2 := stripColonDigits(s)
	if n2 < 0 {
		return s, n1, 1 // "filename:line"
	}

	return s, n2, n1 // "filename:line:col"
}

// parseGoListImportCycleError attempts to parse the given go/packages error as
// an import cycle, returning a diagnostic if successful.
//
// If the error is not detected as an import cycle error, it returns nil, nil.
func parseGoListImportCycleError(ctx context.Context, e packages.Error, mp *metadata.Package, fs file.Source) (*Diagnostic, error) {
	re := regexp.MustCompile(`(.*): import stack: \[(.+)\]`)
	matches := re.FindStringSubmatch(strings.TrimSpace(e.Msg))
	if len(matches) < 3 {
		return nil, nil
	}
	msg := matches[1]
	importList := strings.Split(matches[2], " ")
	// Since the error is relative to the current package. The import that is causing
	// the import cycle error is the second one in the list.
	if len(importList) < 2 {
		return nil, nil
	}
	// Imports have quotation marks around them.
	circImp := strconv.Quote(importList[1])
	for _, uri := range mp.CompiledGoFiles {
		pgf, err := parseGoURI(ctx, fs, uri, parsego.Header)
		if err != nil {
			return nil, err
		}
		// Search file imports for the import that is causing the import cycle.
		for _, imp := range pgf.File.Imports {
			if imp.Path.Value == circImp {
				rng, err := pgf.NodeRange(imp)
				if err != nil {
					return nil, nil
				}

				return &Diagnostic{
					URI:      pgf.URI,
					Range:    rng,
					Severity: protocol.SeverityError,
					Source:   ListError,
					Message:  msg,
				}, nil
			}
		}
	}
	return nil, nil
}

// parseGoURI is a helper to parse the Go file at the given URI from the file
// source fs. The resulting syntax and token.File belong to an ephemeral,
// encapsulated FileSet, so this file stands only on its own: it's not suitable
// to use in a list of file of a package, for example.
//
// It returns an error if the file could not be read.
//
// TODO(rfindley): eliminate this helper.
func parseGoURI(ctx context.Context, fs file.Source, uri protocol.DocumentURI, mode parser.Mode) (*parsego.File, error) {
	fh, err := fs.ReadFile(ctx, uri)
	if err != nil {
		return nil, err
	}
	return parseGoImpl(ctx, token.NewFileSet(), fh, mode, false)
}

// parseModURI is a helper to parse the Mod file at the given URI from the file
// source fs.
//
// It returns an error if the file could not be read.
func parseModURI(ctx context.Context, fs file.Source, uri protocol.DocumentURI) (*ParsedModule, error) {
	fh, err := fs.ReadFile(ctx, uri)
	if err != nil {
		return nil, err
	}
	return parseModImpl(ctx, fh)
}


================================================
FILE: gopls/internal/cache/errors_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"encoding/json"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/protocol"
)

func TestParseErrorMessage(t *testing.T) {
	tests := []struct {
		name             string
		in               string
		expectedFileName string
		expectedLine     int // (missing => 1)
		expectedColumn   int // (missing => 1)
	}{
		{
			name:             "from go list output",
			in:               "\nattributes.go:13:1: expected 'package', found 'type'",
			expectedFileName: "attributes.go",
			expectedLine:     13,
			expectedColumn:   1,
		},
		{
			name:             "windows driver letter",
			in:               "C:\\foo\\bar.go:13: message",
			expectedFileName: "bar.go",
			expectedLine:     13,
			expectedColumn:   1,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			fn, line, col8 := parseGoListError(packages.Error{Msg: tt.in}, ".")

			if !strings.HasSuffix(fn, tt.expectedFileName) {
				t.Errorf("expected filename with suffix %v but got %v", tt.expectedFileName, fn)
			}
			if line != tt.expectedLine {
				t.Errorf("expected line %v but got %v", tt.expectedLine, line)
			}
			if col8 != tt.expectedColumn {
				t.Errorf("expected col %v but got %v", tt.expectedLine, col8)
			}
		})
	}
}

func TestDiagnosticEncoding(t *testing.T) {
	diags := []*Diagnostic{
		{}, // empty
		{
			URI: "file///foo",
			Range: protocol.Range{
				Start: protocol.Position{Line: 4, Character: 2},
				End:   protocol.Position{Line: 6, Character: 7},
			},
			Severity: protocol.SeverityWarning,
			Code:     "red",
			CodeHref: "https://go.dev",
			Source:   "test",
			Message:  "something bad happened",
			Tags:     []protocol.DiagnosticTag{81},
			Related: []protocol.DiagnosticRelatedInformation{
				{
					Location: protocol.Location{
						URI: "file:///other",
						Range: protocol.Range{
							Start: protocol.Position{Line: 3, Character: 6},
							End:   protocol.Position{Line: 4, Character: 9},
						},
					},
					Message: "psst, over here",
				},
			},

			// Fields below are used internally to generate quick fixes. They aren't
			// part of the LSP spec and don't leave the server.
			SuggestedFixes: []SuggestedFix{
				{
					Title: "fix it!",
					Edits: map[protocol.DocumentURI][]protocol.TextEdit{
						"file:///foo": {{
							Range: protocol.Range{
								Start: protocol.Position{Line: 4, Character: 2},
								End:   protocol.Position{Line: 6, Character: 7},
							},
							NewText: "abc",
						}},
						"file:///other": {{
							Range: protocol.Range{
								Start: protocol.Position{Line: 4, Character: 2},
								End:   protocol.Position{Line: 6, Character: 7},
							},
							NewText: "!@#!",
						}},
					},
					Command: &protocol.Command{
						Title:     "run a command",
						Command:   "gopls.fix",
						Arguments: []json.RawMessage{json.RawMessage(`{"a":1}`)},
					},
					ActionKind: protocol.QuickFix,
				},
			},
		},
		{
			URI: "file//bar",
			// other fields tested above
		},
	}

	data := encodeDiagnostics(diags)
	diags2 := decodeDiagnostics(data)

	if diff := cmp.Diff(diags, diags2); diff != "" {
		t.Errorf("decoded diagnostics do not match (-original +decoded):\n%s", diff)
	}
}


================================================
FILE: gopls/internal/cache/filemap.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"iter"
	"path/filepath"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/persistent"
)

// A fileMap maps files in the snapshot, with some additional bookkeeping:
// It keeps track of overlays as well as directories containing any observed
// file.
type fileMap struct {
	files    *persistent.Map[protocol.DocumentURI, file.Handle]
	overlays *persistent.Map[protocol.DocumentURI, *overlay] // the subset of files that are overlays
	dirs     *persistent.Set[string]                         // all dirs containing files; if nil, dirs have not been initialized
}

func newFileMap() *fileMap {
	return &fileMap{
		files:    new(persistent.Map[protocol.DocumentURI, file.Handle]),
		overlays: new(persistent.Map[protocol.DocumentURI, *overlay]),
		dirs:     new(persistent.Set[string]),
	}
}

// clone creates a copy of the fileMap, incorporating the changes specified by
// the changes map.
func (m *fileMap) clone(changes map[protocol.DocumentURI]file.Handle) *fileMap {
	m2 := &fileMap{
		files:    m.files.Clone(),
		overlays: m.overlays.Clone(),
	}
	if m.dirs != nil {
		m2.dirs = m.dirs.Clone()
	}

	// Handle file changes.
	//
	// Note, we can't simply delete the file unconditionally and let it be
	// re-read by the snapshot, as (1) the snapshot must always observe all
	// overlays, and (2) deleting a file forces directories to be reevaluated, as
	// it may be the last file in a directory. We want to avoid that work in the
	// common case where a file has simply changed.
	//
	// For that reason, we also do this in two passes, processing deletions
	// first, as a set before a deletion would result in pointless work.
	for uri, fh := range changes {
		if !fileExists(fh) {
			m2.delete(uri)
		}
	}
	for uri, fh := range changes {
		if fileExists(fh) {
			m2.set(uri, fh)
		}
	}
	return m2
}

func (m *fileMap) destroy() {
	m.files.Destroy()
	m.overlays.Destroy()
	if m.dirs != nil {
		m.dirs.Destroy()
	}
}

// get returns the file handle mapped by the given key, or (nil, false) if the
// key is not present.
func (m *fileMap) get(key protocol.DocumentURI) (file.Handle, bool) {
	return m.files.Get(key)
}

// all returns the sequence of (uri, fh) entries in the map.
func (m *fileMap) all() iter.Seq2[protocol.DocumentURI, file.Handle] {
	return m.files.All()
}

// set stores the given file handle for key, updating overlays and directories
// accordingly.
func (m *fileMap) set(key protocol.DocumentURI, fh file.Handle) {
	m.files.Set(key, fh, nil)

	// update overlays
	if o, ok := fh.(*overlay); ok {
		m.overlays.Set(key, o, nil)
	} else {
		// Setting a non-overlay must delete the corresponding overlay, to preserve
		// the accuracy of the overlay set.
		m.overlays.Delete(key)
	}

	// update dirs, if they have been computed
	if m.dirs != nil {
		m.addDirs(key)
	}
}

// addDirs adds all directories containing u to the dirs set.
func (m *fileMap) addDirs(u protocol.DocumentURI) {
	dir := u.DirPath()
	for dir != "" && !m.dirs.Contains(dir) {
		m.dirs.Add(dir)
		dir = filepath.Dir(dir)
	}
}

// delete removes a file from the map, and updates overlays and dirs
// accordingly.
func (m *fileMap) delete(key protocol.DocumentURI) {
	m.files.Delete(key)
	m.overlays.Delete(key)

	// Deleting a file may cause the set of dirs to shrink; therefore we must
	// re-evaluate the dir set.
	//
	// Do this lazily, to avoid work if there are multiple deletions in a row.
	if m.dirs != nil {
		m.dirs.Destroy()
		m.dirs = nil
	}
}

// getOverlays returns a new unordered array of overlay files.
func (m *fileMap) getOverlays() []*overlay {
	var overlays []*overlay
	for _, o := range m.overlays.All() {
		overlays = append(overlays, o)
	}
	return overlays
}

// getDirs reports returns the set of dirs observed by the fileMap.
//
// This operation mutates the fileMap.
// The result must not be mutated by the caller.
func (m *fileMap) getDirs() *persistent.Set[string] {
	if m.dirs == nil {
		m.dirs = new(persistent.Set[string])
		for uri := range m.files.All() {
			m.addDirs(uri)
		}
	}
	return m.dirs
}


================================================
FILE: gopls/internal/cache/filemap_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"path/filepath"
	"sort"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

func TestFileMap(t *testing.T) {
	const (
		set = iota
		del
	)
	type op struct {
		op      int // set or remove
		path    string
		overlay bool
	}
	tests := []struct {
		label        string
		ops          []op
		wantFiles    []string
		wantOverlays []string
		wantDirs     []string
	}{
		{"empty", nil, nil, nil, nil},
		{"singleton", []op{
			{set, "/a/b", false},
		}, []string{"/a/b"}, nil, []string{"/", "/a"}},
		{"overlay", []op{
			{set, "/a/b", true},
		}, []string{"/a/b"}, []string{"/a/b"}, []string{"/", "/a"}},
		{"replace overlay", []op{
			{set, "/a/b", true},
			{set, "/a/b", false},
		}, []string{"/a/b"}, nil, []string{"/", "/a"}},
		{"multi dir", []op{
			{set, "/a/b", false},
			{set, "/c/d", false},
		}, []string{"/a/b", "/c/d"}, nil, []string{"/", "/a", "/c"}},
		{"empty dir", []op{
			{set, "/a/b", false},
			{set, "/c/d", false},
			{del, "/a/b", false},
		}, []string{"/c/d"}, nil, []string{"/", "/c"}},
	}

	// Normalize paths for windows compatibility.
	normalize := func(path string) string {
		y := filepath.ToSlash(path)
		// Windows paths may start with a drive letter
		if len(y) > 2 && y[1] == ':' && y[0] >= 'A' && y[0] <= 'Z' {
			y = y[2:]
		}
		return y
	}

	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			m := newFileMap()
			for _, op := range test.ops {
				uri := protocol.URIFromPath(filepath.FromSlash(op.path))
				switch op.op {
				case set:
					var fh file.Handle
					if op.overlay {
						fh = &overlay{uri: uri}
					} else {
						fh = &diskFile{uri: uri}
					}
					m.set(uri, fh)
				case del:
					m.delete(uri)
				}
			}

			var gotFiles []string
			for uri := range m.all() {
				gotFiles = append(gotFiles, normalize(uri.Path()))
			}
			sort.Strings(gotFiles)
			if diff := cmp.Diff(test.wantFiles, gotFiles); diff != "" {
				t.Errorf("Files mismatch (-want +got):\n%s", diff)
			}

			var gotOverlays []string
			for _, o := range m.getOverlays() {
				gotOverlays = append(gotOverlays, normalize(o.URI().Path()))
			}
			if diff := cmp.Diff(test.wantOverlays, gotOverlays); diff != "" {
				t.Errorf("Overlays mismatch (-want +got):\n%s", diff)
			}

			var gotDirs []string
			for dir := range m.getDirs().All() {
				gotDirs = append(gotDirs, normalize(dir))
			}
			sort.Strings(gotDirs)
			if diff := cmp.Diff(test.wantDirs, gotDirs); diff != "" {
				t.Errorf("Dirs mismatch (-want +got):\n%s", diff)
			}
		})
	}
}


================================================
FILE: gopls/internal/cache/filterer.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"path"
	"path/filepath"
	"regexp"
	"strings"
)

// PathIncludeFunc creates a function that determines if a given file path
// should be included based on a set of inclusion/exclusion rules.
//
// The `rules` parameter is a slice of strings, where each string represents a
// filtering rule. Each rule consists of an operator (`+` for inclusion, `-`
// for exclusion) followed by a path pattern. See more detail of rules syntax
// at [settings.BuildOptions.DirectoryFilters].
//
// Rules are evaluated in order, and the last matching rule determines
// whether a path is included or excluded.
//
// Examples:
//   - []{"-foo"}: Exclude "foo" at the current depth.
//   - []{"-**foo"}: Exclude "foo" at any depth.
//   - []{"+bar"}: Include "bar" at the current depth.
//   - []{"-foo", "+foo/**/bar"}: Exclude all "foo" at current depth except
//     directory "bar" under "foo" at any depth.
func PathIncludeFunc(rules []string) func(string) bool {
	var matchers []*regexp.Regexp
	var included []bool
	for _, filter := range rules {
		filter = path.Clean(filepath.ToSlash(filter))
		// TODO(dungtuanle): fix: validate [+-] prefix.
		op, prefix := filter[0], filter[1:]
		// convertFilterToRegexp adds "/" at the end of prefix to handle cases
		// where a filter is a prefix of another filter.
		// For example, it prevents [+foobar, -foo] from excluding "foobar".
		matchers = append(matchers, convertFilterToRegexp(filepath.ToSlash(prefix)))
		included = append(included, op == '+')
	}

	return func(path string) bool {
		// Ensure leading and trailing slashes.
		if !strings.HasPrefix(path, "/") {
			path = "/" + path
		}
		if !strings.HasSuffix(path, "/") {
			path += "/"
		}

		// TODO(adonovan): opt: iterate in reverse and break at first match.
		include := true
		for i, filter := range matchers {
			if filter.MatchString(path) {
				include = included[i] // last match wins
			}
		}
		return include
	}
}

// convertFilterToRegexp replaces glob-like operator substrings in a string file path to their equivalent regex forms.
// Supporting glob-like operators:
//   - **: match zero or more complete path segments
func convertFilterToRegexp(filter string) *regexp.Regexp {
	if filter == "" {
		return regexp.MustCompile(".*")
	}
	var ret strings.Builder
	ret.WriteString("^/")
	segs := strings.SplitSeq(filter, "/")
	for seg := range segs {
		// Inv: seg != "" since path is clean.
		if seg == "**" {
			ret.WriteString(".*")
		} else {
			ret.WriteString(regexp.QuoteMeta(seg))
		}
		ret.WriteString("/")
	}
	pattern := ret.String()

	// Remove unnecessary "^.*" prefix, which increased
	// BenchmarkWorkspaceSymbols time by ~20% (even though
	// filter CPU time increased by only by ~2.5%) when the
	// default filter was changed to "**/node_modules".
	pattern = strings.TrimPrefix(pattern, "^/.*")

	return regexp.MustCompile(pattern)
}


================================================
FILE: gopls/internal/cache/fs_memoized.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"os"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/robustio"
)

// A memoizedFS is a file source that memoizes reads, to reduce IO.
type memoizedFS struct {
	mu sync.Mutex

	// filesByID maps existing file inodes to the result of a read.
	// (The read may have failed, e.g. due to EACCES or a delete between stat+read.)
	// Each slice is a non-empty list of aliases: different URIs.
	filesByID map[robustio.FileID][]*diskFile
}

func newMemoizedFS() *memoizedFS {
	return &memoizedFS{filesByID: make(map[robustio.FileID][]*diskFile)}
}

// A diskFile is a file in the filesystem, or a failure to read one.
// It implements the file.Source interface.
type diskFile struct {
	uri     protocol.DocumentURI
	modTime time.Time
	content []byte
	hash    file.Hash
	err     error
}

func (h *diskFile) String() string { return h.uri.Path() }

func (h *diskFile) URI() protocol.DocumentURI { return h.uri }

func (h *diskFile) Identity() file.Identity {
	return file.Identity{
		URI:  h.uri,
		Hash: h.hash,
	}
}

func (h *diskFile) SameContentsOnDisk() bool    { return true }
func (h *diskFile) Version() int32              { return 0 }
func (h *diskFile) Content() ([]byte, error)    { return h.content, h.err }
func (h *diskFile) ModTime() (time.Time, error) { return h.modTime, h.err }

// ReadFile stats and (maybe) reads the file, updates the cache, and returns it.
func (fs *memoizedFS) ReadFile(ctx context.Context, uri protocol.DocumentURI) (file.Handle, error) {
	id, mtime, err := robustio.GetFileID(uri.Path())
	if err != nil {
		// file does not exist
		return &diskFile{
			err: err,
			uri: uri,
		}, nil
	}

	// We check if the file has changed by comparing modification times. Notably,
	// this is an imperfect heuristic as various systems have low resolution
	// mtimes (as much as 1s on WSL or s390x builders), so we only cache
	// filehandles if mtime is old enough to be reliable, meaning that we don't
	// expect a subsequent write to have the same mtime.
	//
	// The coarsest mtime precision we've seen in practice is 1s, so consider
	// mtime to be unreliable if it is less than 2s old. Capture this before
	// doing anything else.
	recentlyModified := time.Since(mtime) < 2*time.Second

	fs.mu.Lock()
	fhs, ok := fs.filesByID[id]
	if ok && fhs[0].modTime.Equal(mtime) {
		var fh *diskFile
		// We have already seen this file and it has not changed.
		for _, h := range fhs {
			if h.uri == uri {
				fh = h
				break
			}
		}
		// No file handle for this exact URI. Create an alias, but share content.
		if fh == nil {
			newFH := *fhs[0]
			newFH.uri = uri
			fh = &newFH
			fhs = append(fhs, fh)
			fs.filesByID[id] = fhs
		}
		fs.mu.Unlock()
		return fh, nil
	}
	fs.mu.Unlock()

	// Unknown file, or file has changed. Read (or re-read) it.
	fh, err := readFile(ctx, uri, mtime) // ~25us
	if err != nil {
		return nil, err // e.g. cancelled (not: read failed)
	}

	fs.mu.Lock()
	if !recentlyModified {
		fs.filesByID[id] = []*diskFile{fh}
	} else {
		delete(fs.filesByID, id)
	}
	fs.mu.Unlock()
	return fh, nil
}

// fileStats returns information about the set of files stored in fs. It is
// intended for debugging only.
func (fs *memoizedFS) fileStats() (files, largest, errs int) {
	fs.mu.Lock()
	defer fs.mu.Unlock()

	files = len(fs.filesByID)
	largest = 0
	errs = 0

	for _, files := range fs.filesByID {
		rep := files[0]
		if len(rep.content) > largest {
			largest = len(rep.content)
		}
		if rep.err != nil {
			errs++
		}
	}
	return files, largest, errs
}

// ioLimit limits the number of parallel file reads per process.
var ioLimit = make(chan struct{}, 128)

func readFile(ctx context.Context, uri protocol.DocumentURI, mtime time.Time) (*diskFile, error) {
	select {
	case ioLimit <- struct{}{}:
	case <-ctx.Done():
		return nil, ctx.Err()
	}
	defer func() { <-ioLimit }()

	ctx, done := event.Start(ctx, "cache.readFile", label.File.Of(uri.Path()))
	_ = ctx
	defer done()

	// It is possible that a race causes us to read a file with different file
	// ID, or whose mtime differs from the given mtime. However, in these cases
	// we expect the client to notify of a subsequent file change, and the file
	// content should be eventually consistent.
	content, err := os.ReadFile(uri.Path()) // ~20us
	if err != nil {
		content = nil // just in case
	}
	return &diskFile{
		modTime: mtime,
		uri:     uri,
		content: content,
		hash:    file.HashOf(content),
		err:     err,
	}, nil
}


================================================
FILE: gopls/internal/cache/fs_overlay.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

// An overlayFS is a file.Source that keeps track of overlays on top of a
// delegate FileSource.
type overlayFS struct {
	delegate file.Source

	mu       sync.Mutex
	overlays map[protocol.DocumentURI]*overlay
}

func newOverlayFS(delegate file.Source) *overlayFS {
	return &overlayFS{
		delegate: delegate,
		overlays: make(map[protocol.DocumentURI]*overlay),
	}
}

// Overlays returns a new unordered array of overlays.
func (fs *overlayFS) Overlays() []*overlay {
	fs.mu.Lock()
	defer fs.mu.Unlock()
	overlays := make([]*overlay, 0, len(fs.overlays))
	for _, overlay := range fs.overlays {
		overlays = append(overlays, overlay)
	}
	return overlays
}

func (fs *overlayFS) ReadFile(ctx context.Context, uri protocol.DocumentURI) (file.Handle, error) {
	fs.mu.Lock()
	overlay, ok := fs.overlays[uri]
	fs.mu.Unlock()
	if ok {
		return overlay, nil
	}
	return fs.delegate.ReadFile(ctx, uri)
}

// An overlay is a file open in the editor. It may have unsaved edits.
// It implements the file.Handle interface, and the implicit contract
// of the debug.FileTmpl template.
type overlay struct {
	uri     protocol.DocumentURI
	content []byte
	modTime time.Time
	hash    file.Hash
	version int32
	kind    file.Kind

	// saved is true if a file matches the state on disk,
	// and therefore does not need to be part of the overlay sent to go/packages.
	saved bool
}

func (o *overlay) String() string { return o.uri.Path() }

func (o *overlay) URI() protocol.DocumentURI { return o.uri }

func (o *overlay) Identity() file.Identity {
	return file.Identity{
		URI:  o.uri,
		Hash: o.hash,
	}
}

func (o *overlay) Content() ([]byte, error)    { return o.content, nil }
func (o *overlay) ModTime() (time.Time, error) { return o.modTime, nil }
func (o *overlay) Version() int32              { return o.version }
func (o *overlay) SameContentsOnDisk() bool    { return o.saved }
func (o *overlay) Kind() file.Kind             { return o.kind }


================================================
FILE: gopls/internal/cache/future.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"sync"
)

// A futureCache is a key-value store of "futures", which are values that might
// not yet be processed. By accessing values using [futureCache.get], the
// caller may share work with other goroutines that require the same key.
//
// This is a relatively common pattern, though this implementation includes the
// following two non-standard additions:
//
//  1. futures are cancellable and retryable. If the context being used to
//     compute the future is cancelled, it will abort the computation. If other
//     goroutes are awaiting the future, they will acquire the right to compute
//     it, and start anew.
//  2. futures may be either persistent or transient. Persistent futures are
//     the standard pattern: the results of the computation are preserved for
//     the lifetime of the cache. However, if the cache is transient
//     (persistent=false), the futures will be discarded once their value has
//     been passed to all awaiting goroutines.
//
// These specific extensions are used to implement the concurrency model of the
// [typeCheckBatch], which allows multiple operations to piggy-back on top of
// an ongoing type checking operation, requesting new packages asynchronously
// without unduly increasing the in-use memory required by the type checking
// pass.
type futureCache[K comparable, V any] struct {
	persistent bool

	mu    sync.Mutex
	cache map[K]*future[V]
}

// newFutureCache returns a futureCache that is ready to coordinate
// computations via [futureCache.get].
//
// If persistent is true, the results of these computations are stored for the
// lifecycle of cache. Otherwise, results are discarded after they have been
// passed to all awaiting goroutines.
func newFutureCache[K comparable, V any](persistent bool) *futureCache[K, V] {
	return &futureCache[K, V]{
		persistent: persistent,
		cache:      make(map[K]*future[V]),
	}
}

type future[V any] struct {
	// refs is the number of goroutines awaiting this future, to be used for
	// cleaning up transient cache entries.
	//
	// Guarded by futureCache.mu.
	refs int

	// done is closed when the future has been fully computed.
	done chan unit

	// acquire used to select an awaiting goroutine to run the computation.
	// acquire is 1-buffered, and initialized with one unit, so that the first
	// requester starts a computation. If that computation is cancelled, the
	// requester pushes the unit back to acquire, so that another goroutine may
	// execute the computation.
	acquire chan unit

	// v and err store the result of the computation, guarded by done.
	v   V
	err error
}

// cacheFunc is the type of a future computation function.
type cacheFunc[V any] func(context.Context) (V, error)

// get retrieves or computes the value corresponding to k.
//
// If the cache if persistent and the value has already been computed, get
// returns the result of the previous computation. Otherwise, get either starts
// a computation or joins an ongoing computation. If that computation is
// cancelled, get will reassign the computation to a new goroutine as long as
// there are awaiters.
//
// Once the computation completes, the result is passed to all awaiting
// goroutines. If the cache is transient (persistent=false), the corresponding
// cache entry is removed, and the next call to get will execute a new
// computation.
//
// It is therefore the responsibility of the caller to ensure that the given
// compute function is safely retryable, and always returns the same value.
func (c *futureCache[K, V]) get(ctx context.Context, k K, compute cacheFunc[V]) (V, error) {
	c.mu.Lock()
	f, ok := c.cache[k]
	if !ok {
		f = &future[V]{
			done:    make(chan unit),
			acquire: make(chan unit, 1),
		}
		f.acquire <- unit{} // make available for computation
		c.cache[k] = f
	}
	f.refs++
	c.mu.Unlock()

	defer func() {
		c.mu.Lock()
		defer c.mu.Unlock()
		f.refs--
		if f.refs == 0 && !c.persistent {
			delete(c.cache, k)
		}
	}()

	var zero V
	select {
	case <-ctx.Done():
		return zero, ctx.Err()
	case <-f.done:
		return f.v, f.err
	case <-f.acquire:
	}

	v, err := compute(ctx)
	if err := ctx.Err(); err != nil {
		f.acquire <- unit{} // hand off work to the next requester
		return zero, err
	}

	f.v = v
	f.err = err
	close(f.done)
	return v, err
}


================================================
FILE: gopls/internal/cache/future_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"fmt"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/sync/errgroup"
)

func TestFutureCache_Persistent(t *testing.T) {
	c := newFutureCache[int, int](true)
	ctx := context.Background()

	var computed atomic.Int32
	compute := func(i int) cacheFunc[int] {
		return func(context.Context) (int, error) {
			computed.Add(1)
			return i, ctx.Err()
		}
	}

	testFutureCache(t, ctx, c, compute)

	// Since this cache is persistent, we should get exactly 10 computations,
	// since there are 10 distinct keys in [testFutureCache].
	if got := computed.Load(); got != 10 {
		t.Errorf("computed %d times, want 10", got)
	}
}

func TestFutureCache_Ephemeral(t *testing.T) {
	c := newFutureCache[int, int](false)
	ctx := context.Background()

	var computed atomic.Int32
	compute := func(i int) cacheFunc[int] {
		return func(context.Context) (int, error) {
			time.Sleep(1 * time.Millisecond)
			computed.Add(1)
			return i, ctx.Err()
		}
	}

	testFutureCache(t, ctx, c, compute)

	// Since this cache is ephemeral, we should get at least 30 computations,
	// since there are 10 distinct keys and three synchronous passes in
	// [testFutureCache].
	if got := computed.Load(); got < 30 {
		t.Errorf("computed %d times, want at least 30", got)
	} else {
		t.Logf("compute ran %d times", got)
	}
}

// testFutureCache starts 100 goroutines concurrently, indexed by j, each
// getting key j%10 from the cache. It repeats this three times, synchronizing
// after each.
//
// This is designed to exercise both concurrent and synchronous access to the
// cache.
func testFutureCache(t *testing.T, ctx context.Context, c *futureCache[int, int], compute func(int) cacheFunc[int]) {
	for range 3 {
		var g errgroup.Group
		for j := range 100 {
			mod := j % 10
			compute := compute(mod)
			g.Go(func() error {
				got, err := c.get(ctx, mod, compute)
				if err == nil && got != mod {
					t.Errorf("get() = %d, want %d", got, mod)
				}
				return err
			})
		}
		if err := g.Wait(); err != nil {
			t.Fatal(err)
		}
	}
}

func TestFutureCache_Retrying(t *testing.T) {
	// This test verifies the retry behavior of cache entries,
	// by checking that cancelled work is handed off to the next awaiter.
	//
	// The setup is a little tricky: 10 goroutines are started, and the first 9
	// are cancelled whereas the 10th is allowed to finish. As a result, the
	// computation should always succeed with value 9.

	ctx := context.Background()

	for _, persistent := range []bool{true, false} {
		t.Run(fmt.Sprintf("persistent=%t", persistent), func(t *testing.T) {
			c := newFutureCache[int, int](persistent)

			var started atomic.Int32

			// compute returns a new cacheFunc that produces the value i, after the
			// provided done channel is closed.
			compute := func(i int, done <-chan struct{}) cacheFunc[int] {
				return func(ctx context.Context) (int, error) {
					started.Add(1)
					select {
					case <-ctx.Done():
						return 0, ctx.Err()
					case <-done:
						return i, nil
					}
				}
			}

			// goroutines are either cancelled, or allowed to complete,
			// as controlled by cancels and dones.
			var (
				cancels = make([]func(), 10)
				dones   = make([]chan struct{}, 10)
			)

			var g errgroup.Group
			var lastValue atomic.Int32 // keep track of the last successfully computed value
			for i := range 10 {
				ctx, cancel := context.WithCancel(ctx)
				done := make(chan struct{})
				cancels[i] = cancel
				dones[i] = done
				compute := compute(i, done)
				g.Go(func() error {
					v, err := c.get(ctx, 0, compute)
					if err == nil {
						lastValue.Store(int32(v))
					}
					return nil
				})
			}
			for _, cancel := range cancels[:9] {
				cancel()
			}
			defer cancels[9]()

			dones[9] <- struct{}{}
			_ = g.Wait() // can't fail

			t.Logf("started %d computations", started.Load())
			if got := lastValue.Load(); got != 9 {
				t.Errorf("after cancelling computation 0-8, got %d, want 9", got)
			}
		})
	}
}


================================================
FILE: gopls/internal/cache/imports.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"fmt"
	"log"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/modindex"
)

// refreshTimer implements delayed asynchronous refreshing of state.
//
// See the [refreshTimer.schedule] documentation for more details.
type refreshTimer struct {
	mu        sync.Mutex
	duration  time.Duration
	timer     *time.Timer
	refreshFn func()
}

// newRefreshTimer constructs a new refresh timer which schedules refreshes
// using the given function.
func newRefreshTimer(refresh func()) *refreshTimer {
	return &refreshTimer{
		refreshFn: refresh,
	}
}

// stop stops any future scheduled refresh.
func (t *refreshTimer) stop() {
	t.mu.Lock()
	defer t.mu.Unlock()

	if t.timer != nil {
		t.timer.Stop()
		t.timer = nil
		t.refreshFn = nil // release resources
	}
}

// schedule schedules the refresh function to run at some point in the future,
// if no existing refresh is already scheduled.
//
// At a minimum, scheduled refreshes are delayed by 30s, but they may be
// delayed longer to keep their expected execution time under 2% of wall clock
// time.
func (t *refreshTimer) schedule() {
	t.mu.Lock()
	defer t.mu.Unlock()

	if t.timer == nil {
		// Don't refresh more than twice per minute.
		// Don't spend more than ~2% of the time refreshing.
		delay := max(30*time.Second, 50*t.duration)
		t.timer = time.AfterFunc(delay, func() {
			start := time.Now()
			t.mu.Lock()
			refreshFn := t.refreshFn
			t.mu.Unlock()
			if refreshFn != nil { // timer may be stopped.
				refreshFn()
				t.mu.Lock()
				t.duration = time.Since(start)
				t.timer = nil
				t.mu.Unlock()
			}
		})
	}
}

// A sharedModCache tracks goimports state for GOMODCACHE directories
// (each session may have its own GOMODCACHE).
//
// This state is refreshed independently of view-specific imports state.
type sharedModCache struct {
	mu     sync.Mutex
	caches map[string]*imports.DirInfoCache // GOMODCACHE -> cache content; never invalidated
	// TODO(rfindley): consider stopping these timers when the session shuts down.
	timers map[string]*refreshTimer // GOMODCACHE -> timer
}

func (c *sharedModCache) dirCache(dir string) *imports.DirInfoCache {
	c.mu.Lock()
	defer c.mu.Unlock()

	cache, ok := c.caches[dir]
	if !ok {
		cache = imports.NewDirInfoCache()
		c.caches[dir] = cache
	}
	return cache
}

// refreshDir schedules a refresh of the given directory, which must be a
// module cache.
func (c *sharedModCache) refreshDir(ctx context.Context, dir string, logf func(string, ...any)) {
	cache := c.dirCache(dir)

	c.mu.Lock()
	defer c.mu.Unlock()
	timer, ok := c.timers[dir]
	if !ok {
		timer = newRefreshTimer(func() {
			_, done := event.Start(ctx, "cache.sharedModCache.refreshDir", label.Directory.Of(dir))
			defer done()
			imports.ScanModuleCache(dir, cache, logf)
		})
		c.timers[dir] = timer
	}

	timer.schedule()
}

// importsState tracks view-specific imports state.
type importsState struct {
	ctx          context.Context
	modCache     *sharedModCache
	refreshTimer *refreshTimer

	mu                sync.Mutex
	processEnv        *imports.ProcessEnv
	cachedModFileHash file.Hash
}

// newImportsState constructs a new imports state for running goimports
// functions via [runProcessEnvFunc].
//
// The returned state will automatically refresh itself following a delay.
func newImportsState(backgroundCtx context.Context, modCache *sharedModCache, env *imports.ProcessEnv) *importsState {
	s := &importsState{
		ctx:        backgroundCtx,
		modCache:   modCache,
		processEnv: env,
	}
	s.refreshTimer = newRefreshTimer(s.refreshProcessEnv)
	s.refreshTimer.schedule()
	return s
}

// modcacheState holds a modindex.Index and controls its updates
type modcacheState struct {
	gomodcache   string
	refreshTimer *refreshTimer

	// (index, indexErr) is zero in the initial state.
	// Thereafter they hold the memoized result pair for getIndex.
	mu       sync.Mutex
	index    *modindex.Index
	indexErr error
}

// newModcacheState constructs a new modcacheState for goimports.
// The returned state is automatically updated until [modcacheState.stopTimer] is called.
func newModcacheState(gomodcache string) *modcacheState {
	s := &modcacheState{
		gomodcache: gomodcache,
	}
	s.refreshTimer = newRefreshTimer(s.refreshIndex)
	go s.refreshIndex()
	return s
}

// getIndex reads the module cache index.
func (s *modcacheState) getIndex() (*modindex.Index, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.index == nil && s.indexErr == nil {
		// getIndex was called before refreshIndex finished.
		// Read, but don't update, whatever index is present.
		s.index, s.indexErr = modindex.Read(s.gomodcache)
	}

	return s.index, s.indexErr
}

func (s *modcacheState) refreshIndex() {
	index, err := modindex.Update(s.gomodcache)
	s.mu.Lock()
	if err != nil {
		if s.indexErr != nil {
			s.indexErr = err // prefer most recent error
		} else if s.index != nil {
			// Keep using stale s.index.
			log.Printf("modcacheState.refreshIndex: %v", err)
		}
	} else {
		s.index, s.indexErr = index, nil // success
	}
	s.mu.Unlock()
}

func (s *modcacheState) stopTimer() {
	s.refreshTimer.stop()
}

// stopTimer stops scheduled refreshes of this imports state.
func (s *importsState) stopTimer() {
	s.refreshTimer.stop()
}

// runProcessEnvFunc runs goimports.
//
// Any call to runProcessEnvFunc will schedule a refresh of the imports state
// at some point in the future, if such a refresh is not already scheduled. See
// [refreshTimer] for more details.
func (s *importsState) runProcessEnvFunc(ctx context.Context, snapshot *Snapshot, fn func(context.Context, *imports.Options) error) error {
	ctx, done := event.Start(ctx, "cache.importsState.runProcessEnvFunc")
	defer done()

	s.mu.Lock()
	defer s.mu.Unlock()

	// Find the hash of active mod files, if any. Using the unsaved content
	// is slightly wasteful, since we'll drop caches a little too often, but
	// the mod file shouldn't be changing while people are autocompleting.
	//
	// TODO(rfindley): consider instead hashing on-disk modfiles here.
	var modFileHash file.Hash
	for m := range snapshot.view.workspaceModFiles {
		fh, err := snapshot.ReadFile(ctx, m)
		if err != nil {
			return err
		}
		modFileHash.XORWith(fh.Identity().Hash)
	}

	// If anything relevant to imports has changed, clear caches and
	// update the processEnv. Clearing caches blocks on any background
	// scans.
	if modFileHash != s.cachedModFileHash {
		s.processEnv.ClearModuleInfo()
		s.cachedModFileHash = modFileHash
	}

	// Run the user function.
	opts := &imports.Options{
		// Defaults.
		AllErrors:   true,
		Comments:    true,
		Fragment:    true,
		FormatOnly:  false,
		TabIndent:   true,
		TabWidth:    8,
		Env:         s.processEnv,
		LocalPrefix: snapshot.Options().Local,
	}

	if err := fn(ctx, opts); err != nil {
		return err
	}

	// Refresh the imports resolver after usage. This may seem counterintuitive,
	// since it means the first ProcessEnvFunc after a long period of inactivity
	// may be stale, but in practice we run ProcessEnvFuncs frequently during
	// active development (e.g. during completion), and so this mechanism will be
	// active while gopls is in use, and inactive when gopls is idle.
	s.refreshTimer.schedule()

	// TODO(rfindley): the GOMODCACHE value used here isn't directly tied to the
	// ProcessEnv.Env["GOMODCACHE"], though they should theoretically always
	// agree. It would be better if we guaranteed this, possibly by setting all
	// required environment variables in ProcessEnv.Env, to avoid the redundant
	// Go command invocation.
	gomodcache := snapshot.view.folder.Env.GOMODCACHE
	s.modCache.refreshDir(s.ctx, gomodcache, s.processEnv.Logf)

	return nil
}

func (s *importsState) refreshProcessEnv() {
	ctx, done := event.Start(s.ctx, "cache.importsState.refreshProcessEnv")
	defer done()

	start := time.Now()

	s.mu.Lock()
	resolver, err := s.processEnv.GetResolver()
	s.mu.Unlock()
	if err != nil {
		event.Error(s.ctx, "failed to get import resolver", err)
		return
	}

	event.Log(s.ctx, "background imports cache refresh starting")
	resolver2 := resolver.ClearForNewScan()

	// Prime the new resolver before updating the processEnv, so that gopls
	// doesn't wait on an unprimed cache.
	if err := imports.PrimeCache(context.Background(), resolver2); err == nil {
		event.Log(ctx, fmt.Sprintf("background refresh finished after %v", time.Since(start)))
	} else {
		event.Log(ctx, fmt.Sprintf("background refresh finished after %v", time.Since(start)), keys.Err.Of(err))
	}

	s.mu.Lock()
	s.processEnv.UpdateResolver(resolver2)
	s.mu.Unlock()
}


================================================
FILE: gopls/internal/cache/keys.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

// session event tracing

import (
	"golang.org/x/tools/internal/event/label"
)

var (
	KeyCreateSession   = NewSessionKey("create_session", "A new session was added")
	KeyUpdateSession   = NewSessionKey("update_session", "Updated information about a session")
	KeyShutdownSession = NewSessionKey("shutdown_session", "A session was shut down")
)

// SessionKey represents an event label key that has a *Session value.
type SessionKey struct {
	name        string
	description string
}

// NewSessionKey creates a new Key for *Session values.
func NewSessionKey(name, description string) *SessionKey {
	return &SessionKey{name: name, description: description}
}

func (k *SessionKey) Name() string        { return k.name }
func (k *SessionKey) Description() string { return k.description }

func (k *SessionKey) Append(buf []byte, l label.Label) []byte {
	return append(buf, k.From(l).ID()...)
}

// Of creates a new Label with this key and the supplied session.
func (k *SessionKey) Of(v *Session) label.Label { return label.OfValue(k, v) }

// Get can be used to get the session for the key from a label.Map.
func (k *SessionKey) Get(lm label.Map) *Session {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return nil
}

// From can be used to get the session value from a Label.
func (k *SessionKey) From(t label.Label) *Session {
	err, _ := t.UnpackValue().(*Session)
	return err
}


================================================
FILE: gopls/internal/cache/load.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/types"
	"path/filepath"
	"slices"
	"sort"
	"strings"
	"sync/atomic"
	"time"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/immutable"
	"golang.org/x/tools/gopls/internal/util/pathutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/xcontext"
)

var loadID uint64 // atomic identifier for loads

// errNoPackages indicates that a load query matched no packages.
var errNoPackages = errors.New("no packages returned")

// load calls packages.Load for the given scopes, updating package metadata,
// import graph, and mapped files with the result.
//
// The resulting error may wrap the moduleErrorMap error type, representing
// errors associated with specific modules.
//
// If scopes contains a file scope there must be exactly one scope.
func (s *Snapshot) load(ctx context.Context, allowNetwork AllowNetwork, scopes ...loadScope) (err error) {
	if ctx.Err() != nil {
		// Check context cancellation before incrementing id below: a load on a
		// cancelled context should be a no-op.
		return ctx.Err()
	}
	id := atomic.AddUint64(&loadID, 1)
	eventName := fmt.Sprintf("go/packages.Load #%d", id) // unique name for logging

	var query []string
	var standalone bool // whether this is a load of a standalone file

	// Keep track of module query -> module path so that we can later correlate query
	// errors with errors.
	moduleQueries := make(map[string]string)

	for _, scope := range scopes {
		switch scope := scope.(type) {
		case packageLoadScope:
			// The only time we pass package paths is when we're doing a
			// partial workspace load. In those cases, the paths came back from
			// go list and should already be GOPATH-vendorized when appropriate.
			query = append(query, string(scope))

		case fileLoadScope:
			// Given multiple scopes, the resulting load might contain inaccurate
			// information. For example go/packages returns at most one command-line
			// arguments package, and does not handle a combination of standalone
			// files and packages.
			uri := protocol.DocumentURI(scope)
			if len(scopes) > 1 {
				panic(fmt.Sprintf("internal error: load called with multiple scopes when a file scope is present (file: %s)", uri))
			}
			fh, err := s.ReadFile(ctx, uri)
			if err != nil || fh == nil || s.FileKind(fh) != file.Go {
				// Don't try to load a file that doesn't exist, or isn't a go file.
				continue
			}
			contents, err := fh.Content()
			if err != nil {
				continue
			}
			if isStandaloneFile(contents, s.Options().StandaloneTags) {
				standalone = true
				query = append(query, uri.Path())
			} else {
				query = append(query, fmt.Sprintf("file=%s", uri.Path()))
			}

		case moduleLoadScope:
			modQuery := fmt.Sprintf("%s%c...", scope.dir, filepath.Separator)
			query = append(query, modQuery)
			moduleQueries[modQuery] = scope.modulePath

		case viewLoadScope:
			// If we are outside of GOPATH, a module, or some other known
			// build system, don't load subdirectories.
			if s.view.typ == AdHocView {
				query = append(query, "./")
			} else {
				query = append(query, "./...")
			}

		default:
			panic(fmt.Sprintf("unknown scope type %T", scope))
		}
	}
	if len(query) == 0 {
		return nil
	}
	sort.Strings(query) // for determinism

	ctx, done := event.Start(ctx, "cache.snapshot.load", label.Query.Of(query))
	defer done()

	startTime := time.Now()

	// Set a last resort deadline on packages.Load since it calls the go
	// command, which may hang indefinitely if it has a bug. golang/go#42132
	// and golang/go#42255 have more context.
	ctx, cancel := context.WithTimeout(ctx, 10*time.Minute)
	defer cancel()

	cfg := s.config(ctx, allowNetwork)
	pkgs, err := packages.Load(cfg, query...)

	// If the context was canceled, return early. Otherwise, we might be
	// type-checking an incomplete result. Check the context directly,
	// because go/packages adds extra information to the error.
	if ctx.Err() != nil {
		return ctx.Err()
	}

	// This log message is sought for by TestReloadOnlyOnce.
	{
		lbls := append(s.Labels(),
			label.Query.Of(query),
			label.PackageCount.Of(len(pkgs)),
			label.Duration.Of(time.Since(startTime)),
		)
		if err != nil {
			event.Error(ctx, eventName, err, lbls...)
		} else {
			event.Log(ctx, eventName, lbls...)
		}
	}

	if err != nil {
		return fmt.Errorf("packages.Load error: %w", err)
	}

	if standalone {
		// Handle standalone package result.
		//
		// In general, this should just be a single "command-line-arguments"
		// package containing the requested file. However, if the file is a test
		// file, go/packages may return test variants of the command-line-arguments
		// package. We don't support this; theoretically we could, but it seems
		// unnecessarily complicated.
		//
		// It's possible that we get no packages here, for example if the file is a
		// cgo file and cgo is not enabled.
		var standalonePkg *packages.Package
		for _, pkg := range pkgs {
			if pkg.ID == "command-line-arguments" {
				if standalonePkg != nil {
					return fmt.Errorf("go/packages returned multiple standalone packages")
				}
				standalonePkg = pkg
			} else if pkg.ForTest == "" && !strings.HasSuffix(pkg.ID, ".test") {
				return fmt.Errorf("go/packages returned unexpected package %q for standalone file", pkg.ID)
			}
		}
		if standalonePkg == nil {
			return fmt.Errorf("go/packages failed to return non-test standalone package")
		}
		if len(standalonePkg.CompiledGoFiles) > 0 {
			pkgs = []*packages.Package{standalonePkg}
		} else {
			pkgs = nil
		}
	}

	if len(pkgs) == 0 {
		return fmt.Errorf("packages.Load error: %w", errNoPackages)
	}

	moduleErrs := make(map[string][]packages.Error) // module path -> errors
	filterFunc := s.view.filterFunc()
	newMetadata := make(map[PackageID]*metadata.Package)
	for _, pkg := range pkgs {
		if pkg.Module != nil && strings.Contains(pkg.Module.Path, "command-line-arguments") {
			// golang/go#61543: modules containing "command-line-arguments" cause
			// gopls to get all sorts of confused, because anything containing the
			// string "command-line-arguments" is treated as a script. And yes, this
			// happened in practice! (https://xkcd.com/327). Rather than try to work
			// around this very rare edge case, just fail loudly.
			return fmt.Errorf(`load failed: module name in %s contains "command-line-arguments", which is disallowed`, pkg.Module.GoMod)
		}
		// The Go command returns synthetic list results for module queries that
		// encountered module errors.
		//
		// For example, given a module path a.mod, we'll query for "a.mod/..." and
		// the go command will return a package named "a.mod/..." holding this
		// error. Save it for later interpretation.
		//
		// See golang/go#50862 for more details.
		if mod := moduleQueries[pkg.PkgPath]; mod != "" { // a synthetic result for the unloadable module
			if len(pkg.Errors) > 0 {
				moduleErrs[mod] = pkg.Errors
			}
			continue
		}

		if s.Options().VerboseOutput {
			event.Log(ctx, eventName, append(
				s.Labels(),
				label.Package.Of(pkg.ID),
				label.Files.Of(pkg.CompiledGoFiles))...)
		}

		// Ignore packages with no sources, since we will never be able to
		// correctly invalidate that metadata.
		if len(pkg.GoFiles) == 0 && len(pkg.CompiledGoFiles) == 0 {
			continue
		}
		// Special case for the builtin package, as it has no dependencies.
		if pkg.PkgPath == "builtin" {
			if len(pkg.GoFiles) != 1 {
				return fmt.Errorf("only expected 1 file for builtin, got %v", len(pkg.GoFiles))
			}
			s.setBuiltin(pkg.GoFiles[0])
			continue
		}
		if pkg.ForTest == "builtin" {
			// We don't care about test variants of builtin. This caused test
			// failures in https://go.dev/cl/620196, when a test file was added to
			// builtin.
			continue
		}
		// Skip test main packages.
		if isTestMain(pkg, s.view.folder.Env.GOCACHE) {
			continue
		}
		// Skip filtered packages. They may be added anyway if they're
		// dependencies of non-filtered packages.
		//
		// TODO(rfindley): why exclude metadata arbitrarily here? It should be safe
		// to capture all metadata.
		// TODO(rfindley): what about compiled go files?
		if allFilesExcluded(pkg.GoFiles, filterFunc) {
			continue
		}
		buildMetadata(newMetadata, cfg.Dir, standalone, pkg)
	}

	s.mu.Lock()

	// Assert the invariant s.packages.Get(id).m == s.meta.metadata[id].
	for id, ph := range s.packages.All() {
		if s.meta.Packages[id] != ph.mp {
			panic("inconsistent metadata")
		}
	}

	// Compute the minimal metadata updates (for Clone)
	// required to preserve the above invariant.
	var files []protocol.DocumentURI // files to preload
	seenFiles := make(map[protocol.DocumentURI]bool)
	updates := make(map[PackageID]*metadata.Package)
	for _, mp := range newMetadata {
		if existing := s.meta.Packages[mp.ID]; existing == nil {
			// Record any new files we should pre-load.
			for _, uri := range mp.CompiledGoFiles {
				if !seenFiles[uri] {
					seenFiles[uri] = true
					files = append(files, uri)
				}
			}
			updates[mp.ID] = mp
			s.shouldLoad.Delete(mp.ID)
		}
	}

	if s.Options().VerboseOutput {
		event.Log(ctx, fmt.Sprintf("%s: updating metadata for %d packages", eventName, len(updates)))
	}

	meta := s.meta.Update(updates)
	workspacePackages := computeWorkspacePackagesLocked(ctx, s, meta)
	s.meta = meta
	s.workspacePackages = workspacePackages

	s.mu.Unlock()

	// Opt: preLoad files in parallel.
	//
	// Requesting files in batch optimizes the underlying filesystem reads.
	// However, this is also currently necessary for correctness: populating all
	// files in the snapshot is necessary for certain operations that rely on the
	// completeness of the file map, e.g. computing the set of directories to
	// watch.
	//
	// TODO(rfindley, golang/go#57558): determine the set of directories based on
	// loaded packages, so that reading files here is not necessary for
	// correctness.
	s.preloadFiles(ctx, files)

	if len(moduleErrs) > 0 {
		return &moduleErrorMap{moduleErrs}
	}

	return nil
}

type moduleErrorMap struct {
	errs map[string][]packages.Error // module path -> errors
}

func (m *moduleErrorMap) Error() string {
	var paths []string // sort for stability
	for path, errs := range m.errs {
		if len(errs) > 0 { // should always be true, but be cautious
			paths = append(paths, path)
		}
	}
	sort.Strings(paths)

	var buf bytes.Buffer
	fmt.Fprintf(&buf, "%d modules have errors:\n", len(paths))
	for _, path := range paths {
		fmt.Fprintf(&buf, "\t%s:%s\n", path, m.errs[path][0].Msg)
	}

	return buf.String()
}

// config returns the configuration used for the snapshot's interaction with
// the go/packages API. It uses the given working directory.
//
// TODO(rstambler): go/packages requires that we do not provide overlays for
// multiple modules in one config, so buildOverlay needs to filter overlays by
// module.
// TODO(rfindley): ^^ is this still true?
func (s *Snapshot) config(ctx context.Context, allowNetwork AllowNetwork) *packages.Config {
	cfg := &packages.Config{
		Context:    ctx,
		Dir:        s.view.root.Path(),
		Env:        s.view.Env(),
		BuildFlags: slices.Clone(s.view.folder.Options.BuildFlags),
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedCompiledGoFiles |
			packages.NeedImports |
			packages.NeedDeps |
			packages.NeedTypesSizes |
			packages.NeedModule |
			packages.NeedEmbedFiles |
			packages.LoadMode(packagesinternal.DepsErrors) |
			packages.NeedForTest,
		Fset:    nil, // we do our own parsing
		Overlay: s.buildOverlays(),
		Logf: func(format string, args ...any) {
			if s.view.folder.Options.VerboseOutput {
				event.Log(ctx, fmt.Sprintf(format, args...))
			}
		},
		Tests: true,
	}
	if !allowNetwork {
		cfg.Env = append(cfg.Env, "GOPROXY=off")
	}
	// We want to type check cgo code if go/types supports it.
	if typesinternal.SetUsesCgo(&types.Config{}) {
		cfg.Mode |= packages.LoadMode(packagesinternal.TypecheckCgo)
	}
	return cfg
}

// buildMetadata populates the updates map with metadata updates to
// apply, based on the given pkg. It recurs through pkg.Imports to ensure that
// metadata exists for all dependencies.
//
// Returns the metadata.Package that was built (or which was already present in
// updates), or nil if the package could not be built. Notably, the resulting
// metadata.Package may have an ID that differs from pkg.ID.
func buildMetadata(updates map[PackageID]*metadata.Package, loadDir string, standalone bool, pkg *packages.Package) *metadata.Package {
	// Allow for multiple ad-hoc packages in the workspace (see #47584).
	pkgPath := PackagePath(pkg.PkgPath)
	id := PackageID(pkg.ID)

	if metadata.IsCommandLineArguments(id) {
		var f string // file to use as disambiguating suffix
		if len(pkg.GoFiles) > 0 {
			f = pkg.GoFiles[0]

			// If there are multiple files, we can't use only the first. Note that we
			// consider GoFiles, rather than CompiledGoFiles, as there can be
			// multiple CompiledGoFiles in the presence of cgo processing, whereas a
			// command-line-arguments package should always have exactly one nominal
			// Go source file. (See golang/go#64557.)
			if len(pkg.GoFiles) > 1 {
				bug.Reportf("unexpected files in command-line-arguments package: %v", pkg.GoFiles)
				return nil
			}
		} else if len(pkg.IgnoredFiles) > 0 {
			// A file=empty.go query results in IgnoredFiles=[empty.go].
			f = pkg.IgnoredFiles[0]
		} else {
			bug.Reportf("command-line-arguments package has neither GoFiles nor IgnoredFiles")
			return nil
		}
		id = PackageID(pkg.ID + f)
		pkgPath = PackagePath(pkg.PkgPath + f)
	}

	// Duplicate?
	if existing, ok := updates[id]; ok {
		// A package was encountered twice due to shared
		// subgraphs (common) or cycles (rare). Although "go
		// list" usually breaks cycles, we don't rely on it.
		// breakImportCycles in metadataGraph.Clone takes care
		// of it later.
		return existing
	}

	if pkg.TypesSizes == nil {
		panic(id + ".TypeSizes is nil")
	}

	// Recreate the metadata rather than reusing it to avoid locking.
	mp := &metadata.Package{
		ID:         id,
		PkgPath:    pkgPath,
		Name:       PackageName(pkg.Name),
		ForTest:    PackagePath(pkg.ForTest),
		TypesSizes: pkg.TypesSizes,
		LoadDir:    loadDir,
		Module:     pkg.Module,
		Errors:     pkg.Errors,
		DepsErrors: packagesinternal.GetDepsErrors(pkg),
		Standalone: standalone,
	}

	updates[id] = mp

	copyURIs := func(dst *[]protocol.DocumentURI, src []string) {
		for _, filename := range src {
			*dst = append(*dst, protocol.URIFromPath(filename))
		}
	}
	copyURIs(&mp.CompiledGoFiles, pkg.CompiledGoFiles)
	copyURIs(&mp.GoFiles, pkg.GoFiles)
	copyURIs(&mp.IgnoredFiles, pkg.IgnoredFiles)
	copyURIs(&mp.OtherFiles, pkg.OtherFiles)

	depsByImpPath := make(map[ImportPath]PackageID)
	depsByPkgPath := make(map[PackagePath]PackageID)
	for importPath, imported := range pkg.Imports {
		importPath := ImportPath(importPath)

		// It is not an invariant that importPath == imported.PkgPath.
		// For example, package "net" imports "golang.org/x/net/dns/dnsmessage"
		// which refers to the package whose ID and PkgPath are both
		// "vendor/golang.org/x/net/dns/dnsmessage". Notice the ImportMap,
		// which maps ImportPaths to PackagePaths:
		//
		// $ go list -json net vendor/golang.org/x/net/dns/dnsmessage
		// {
		// 	"ImportPath": "net",
		// 	"Name": "net",
		// 	"Imports": [
		// 		"C",
		// 		"vendor/golang.org/x/net/dns/dnsmessage",
		// 		"vendor/golang.org/x/net/route",
		// 		...
		// 	],
		// 	"ImportMap": {
		// 		"golang.org/x/net/dns/dnsmessage": "vendor/golang.org/x/net/dns/dnsmessage",
		// 		"golang.org/x/net/route": "vendor/golang.org/x/net/route"
		// 	},
		//      ...
		// }
		// {
		// 	"ImportPath": "vendor/golang.org/x/net/dns/dnsmessage",
		// 	"Name": "dnsmessage",
		//      ...
		// }
		//
		// (Beware that, for historical reasons, go list uses
		// the JSON field "ImportPath" for the package's
		// path--effectively the linker symbol prefix.)
		//
		// The example above is slightly special to go list
		// because it's in the std module.  Otherwise,
		// vendored modules are simply modules whose directory
		// is vendor/ instead of GOMODCACHE, and the
		// import path equals the package path.
		//
		// But in GOPATH (non-module) mode, it's possible for
		// package vendoring to cause a non-identity ImportMap,
		// as in this example:
		//
		// $ cd $HOME/src
		// $ find . -type f
		// ./b/b.go
		// ./vendor/example.com/a/a.go
		// $ cat ./b/b.go
		// package b
		// import _ "example.com/a"
		// $ cat ./vendor/example.com/a/a.go
		// package a
		// $ GOPATH=$HOME GO111MODULE=off go list -json ./b | grep -A2 ImportMap
		//     "ImportMap": {
		//         "example.com/a": "vendor/example.com/a"
		//     },

		// Don't remember any imports with significant errors.
		//
		// The len=0 condition is a heuristic check for imports of
		// non-existent packages (for which go/packages will create
		// an edge to a synthesized node). The heuristic is unsound
		// because some valid packages have zero files, for example,
		// a directory containing only the file p_test.go defines an
		// empty package p.
		// TODO(adonovan): clarify this. Perhaps go/packages should
		// report which nodes were synthesized.
		if importPath != "unsafe" && len(imported.CompiledGoFiles) == 0 {
			depsByImpPath[importPath] = "" // missing
			continue
		}

		// Don't record self-import edges.
		// (This simplifies metadataGraph's cycle check.)
		if PackageID(imported.ID) == id {
			if len(pkg.Errors) == 0 {
				bug.Reportf("self-import without error in package %s", id)
			}
			continue
		}

		dep := buildMetadata(updates, loadDir, false, imported) // only top level packages can be standalone

		// Don't record edges to packages with no name, as they cause trouble for
		// the importer (golang/go#60952).
		//
		// Also don't record edges to packages whose ID was modified (i.e.
		// command-line-arguments packages), as encountered in golang/go#66109. In
		// this case, we could theoretically keep the edge through dep.ID, but
		// since this import doesn't make any sense in the first place, we instead
		// choose to consider it invalid.
		//
		// However, we do want to insert these packages into the update map
		// (buildMetadata above), so that we get type-checking diagnostics for the
		// invalid packages.
		if dep == nil || dep.ID != PackageID(imported.ID) || imported.Name == "" {
			depsByImpPath[importPath] = "" // missing
			continue
		}

		depsByImpPath[importPath] = PackageID(imported.ID)
		depsByPkgPath[PackagePath(imported.PkgPath)] = PackageID(imported.ID)
	}
	mp.DepsByImpPath = depsByImpPath
	mp.DepsByPkgPath = depsByPkgPath
	return mp

	// m.Diagnostics is set later in the loading pass, using
	// computeLoadDiagnostics.
}

// computeLoadDiagnostics computes and sets m.Diagnostics for the given metadata m.
//
// It should only be called during package handle construction in buildPackageHandle.
func computeLoadDiagnostics(ctx context.Context, snapshot *Snapshot, mp *metadata.Package) []*Diagnostic {
	var diags []*Diagnostic
	for _, packagesErr := range mp.Errors {
		// Filter out parse errors from go list. We'll get them when we
		// actually parse, and buggy overlay support may generate spurious
		// errors. (See TestNewModule_Issue38207.)
		if strings.Contains(packagesErr.Msg, "expected '") {
			continue
		}
		pkgDiags, err := goPackagesErrorDiagnostics(ctx, packagesErr, mp, snapshot)
		if err != nil {
			// There are certain cases where the go command returns invalid
			// positions, so we cannot panic or even bug.Reportf here.
			event.Error(ctx, "unable to compute positions for list errors", err, label.Package.Of(string(mp.ID)))
			continue
		}
		diags = append(diags, pkgDiags...)
	}

	// TODO(rfindley): this is buggy: an insignificant change to a modfile
	// (or an unsaved modfile) could affect the position of deps errors,
	// without invalidating the package.
	depsDiags, err := depsErrors(ctx, snapshot, mp)
	if err != nil {
		if ctx.Err() == nil {
			// TODO(rfindley): consider making this a bug.Reportf. depsErrors should
			// not normally fail.
			event.Error(ctx, "unable to compute deps errors", err, label.Package.Of(string(mp.ID)))
		}
	} else {
		diags = append(diags, depsDiags...)
	}
	return diags
}

// isWorkspacePackageLocked reports whether p is a workspace package for the
// snapshot s.
//
// Workspace packages are packages that we consider the user to be actively
// working on. As such, they are re-diagnosed on every keystroke, and searched
// for various workspace-wide queries such as references or workspace symbols.
//
// See the commentary inline for a description of the workspace package
// heuristics.
//
// s.mu must be held while calling this function.
//
// TODO(rfindley): remove 'meta' from this function signature. Whether or not a
// package is a workspace package should depend only on the package, view
// definition, and snapshot file source. While useful, the heuristic
// "allFilesHaveRealPackages" does not add that much value and is path
// dependent as it depends on the timing of loads.
func isWorkspacePackageLocked(ctx context.Context, s *Snapshot, meta *metadata.Graph, pkg *metadata.Package) bool {
	if metadata.IsCommandLineArguments(pkg.ID) {
		// Ad-hoc command-line-arguments packages aren't workspace packages.
		// With zero-config gopls (golang/go#57979) they should be very rare, as
		// they should only arise when the user opens a file outside the workspace
		// which isn't present in the import graph of a workspace package.
		//
		// Considering them as workspace packages tends to be racy, as they don't
		// deterministically belong to any view.
		if !pkg.Standalone {
			return false
		}

		// If all the files contained in pkg have a real package, we don't need to
		// keep pkg as a workspace package.
		if allFilesHaveRealPackages(meta, pkg) {
			return false
		}

		// For now, allow open standalone packages (i.e. go:build ignore) to be
		// workspace packages, but this means they could belong to multiple views.
		return containsOpenFileLocked(s, pkg)
	}

	// If a real package is open, consider it to be part of the workspace.
	//
	// TODO(rfindley): reconsider this. In golang/go#66145, we saw that even if a
	// View sees a real package for a file, it doesn't mean that View is able to
	// cleanly diagnose the package. Yet, we do want to show diagnostics for open
	// packages outside the workspace. Is there a better way to ensure that only
	// the 'best' View gets a workspace package for the open file?
	if containsOpenFileLocked(s, pkg) {
		return true
	}

	// Apply filtering logic.
	//
	// Workspace packages must contain at least one non-filtered file.
	filterFunc := s.view.filterFunc()
	uris := make(map[protocol.DocumentURI]unit) // filtered package URIs
	for _, uri := range slices.Concat(pkg.CompiledGoFiles, pkg.GoFiles) {
		if !strings.Contains(string(uri), "/vendor/") && !filterFunc(uri) {
			uris[uri] = struct{}{}
		}
	}
	if len(uris) == 0 {
		return false // no non-filtered files
	}

	// For non-module views (of type GOPATH or AdHoc), or if
	// expandWorkspaceToModule is unset, workspace packages must be contained in
	// the workspace folder.
	//
	// For module views (of type GoMod or GoWork), packages must in any case be
	// in a workspace module (enforced below).
	if !s.view.typ.usesModules() || !s.Options().ExpandWorkspaceToModule {
		folder := s.view.folder.Dir.Path()
		inFolder := false
		for uri := range uris {
			if pathutil.InDir(folder, uri.Path()) {
				inFolder = true
				break
			}
		}
		if !inFolder {
			return false
		}
	}

	// In module mode, a workspace package must be contained in a workspace
	// module.
	if s.view.typ.usesModules() {
		var modURI protocol.DocumentURI
		if pkg.Module != nil {
			modURI = protocol.URIFromPath(pkg.Module.GoMod)
		} else {
			// golang/go#65816: for std and cmd, Module is nil.
			// Fall back to an inferior heuristic.
			if len(pkg.CompiledGoFiles) == 0 {
				return false // need at least one file to guess the go.mod file
			}
			dir := pkg.CompiledGoFiles[0].Dir()
			var err error
			modURI, err = findRootPattern(ctx, dir, "go.mod", lockedSnapshot{s})
			if err != nil || modURI == "" {
				// err != nil implies context cancellation, in which case the result of
				// this query does not matter.
				return false
			}
		}
		_, ok := s.view.workspaceModFiles[modURI]
		return ok
	}

	return true // an ad-hoc package or GOPATH package
}

// containsOpenFileLocked reports whether any file referenced by m is open in
// the snapshot s.
//
// s.mu must be held while calling this function.
func containsOpenFileLocked(s *Snapshot, mp *metadata.Package) bool {
	uris := map[protocol.DocumentURI]struct{}{}
	for _, uri := range mp.CompiledGoFiles {
		uris[uri] = struct{}{}
	}
	for _, uri := range mp.GoFiles {
		uris[uri] = struct{}{}
	}

	for uri := range uris {
		fh, _ := s.files.get(uri)
		if _, open := fh.(*overlay); open {
			return true
		}
	}
	return false
}

// computeWorkspacePackagesLocked computes workspace packages in the
// snapshot s for the given metadata graph. The result does not
// contain intermediate test variants.
//
// s.mu must be held while calling this function.
func computeWorkspacePackagesLocked(ctx context.Context, s *Snapshot, meta *metadata.Graph) immutable.Map[PackageID, PackagePath] {
	// The provided context is used for reading snapshot files, which can only
	// fail due to context cancellation. Don't let this happen as it could lead
	// to inconsistent results.
	ctx = xcontext.Detach(ctx)
	workspacePackages := make(map[PackageID]PackagePath)
	for _, mp := range meta.Packages {
		if !isWorkspacePackageLocked(ctx, s, meta, mp) {
			continue
		}

		switch {
		case mp.ForTest == "":
			// A normal package.
			workspacePackages[mp.ID] = mp.PkgPath
		case mp.ForTest == mp.PkgPath, mp.ForTest+"_test" == mp.PkgPath:
			// The test variant of some workspace package or its x_test.
			// To load it, we need to load the non-test variant with -test.
			//
			// Notably, this excludes intermediate test variants from workspace
			// packages.
			assert(!mp.IsIntermediateTestVariant(), "unexpected ITV")
			workspacePackages[mp.ID] = mp.ForTest
		}
	}
	return immutable.MapOf(workspacePackages)
}

// allFilesHaveRealPackages reports whether all files referenced by m are
// contained in a "real" package (not command-line-arguments).
//
// If m is valid but all "real" packages containing any file are invalid, this
// function returns false.
//
// If m is not a command-line-arguments package, this is trivially true.
func allFilesHaveRealPackages(g *metadata.Graph, mp *metadata.Package) bool {
	n := len(mp.CompiledGoFiles)
checkURIs:
	for _, uri := range slices.Concat(mp.CompiledGoFiles[0:n:n], mp.GoFiles) {
		for _, pkg := range g.ForFile[uri] {
			if !metadata.IsCommandLineArguments(pkg.ID) {
				continue checkURIs
			}
		}
		return false
	}
	return true
}

func isTestMain(pkg *packages.Package, gocache string) bool {
	// Test mains must have an import path that ends with ".test".
	if !strings.HasSuffix(pkg.PkgPath, ".test") {
		return false
	}
	// Test main packages are always named "main".
	if pkg.Name != "main" {
		return false
	}
	// Test mains always have exactly one GoFile that is in the build cache.
	if len(pkg.GoFiles) > 1 {
		return false
	}
	if !pathutil.InDir(gocache, pkg.GoFiles[0]) {
		return false
	}
	return true
}


================================================
FILE: gopls/internal/cache/metadata/cycle_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package metadata

import (
	"maps"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/util/bug"
)

func init() {
	bug.PanicOnBugs = true
}

// This is an internal test of the breakImportCycles logic.
func TestBreakImportCycles(t *testing.T) {

	// parse parses an import dependency graph.
	// The input is a semicolon-separated list of node descriptions.
	// Each node description is a package ID, optionally followed by
	// "->" and a comma-separated list of successor IDs.
	// Thus "a->b;b->c,d;e" represents the set of nodes {a,b,e}
	// and the set of edges {a->b, b->c, b->d}.
	parse := func(s string) map[PackageID]*Package {
		m := make(map[PackageID]*Package)
		makeNode := func(name string) *Package {
			id := PackageID(name)
			n, ok := m[id]
			if !ok {
				n = &Package{
					ID:            id,
					DepsByPkgPath: make(map[PackagePath]PackageID),
				}
				m[id] = n
			}
			return n
		}
		if s != "" {
			for item := range strings.SplitSeq(s, ";") {
				nodeID, succIDs, ok := strings.Cut(item, "->")
				node := makeNode(nodeID)
				if ok {
					for succID := range strings.SplitSeq(succIDs, ",") {
						node.DepsByPkgPath[PackagePath(succID)] = PackageID(succID)
					}
				}
			}
		}
		return m
	}

	// Sanity check of cycle detector.
	{
		got := cyclic(parse("a->b;b->c;c->a,d"))
		has := func(s string) bool { return strings.Contains(got, s) }
		if !(has("a->b") && has("b->c") && has("c->a") && !has("d")) {
			t.Fatalf("cyclic: got %q, want a->b->c->a or equivalent", got)
		}
	}

	// format formats an import graph, in lexicographic order,
	// in the notation of parse, but with a "!" after the name
	// of each node that has errors.
	format := func(graph map[PackageID]*Package) string {
		var items []string
		for _, mp := range graph {
			item := string(mp.ID)
			if len(mp.Errors) > 0 {
				item += "!"
			}
			var succs []string
			for _, depID := range mp.DepsByPkgPath {
				succs = append(succs, string(depID))
			}
			if succs != nil {
				sort.Strings(succs)
				item += "->" + strings.Join(succs, ",")
			}
			items = append(items, item)
		}
		sort.Strings(items)
		return strings.Join(items, ";")
	}

	// We needn't test self-cycles as they are eliminated at Metadata construction.
	for _, test := range []struct {
		metadata, updates, want string
	}{
		// Simple 2-cycle.
		{"a->b", "b->a",
			"a->b;b!"}, // broke b->a

		{"a->b;b->c;c", "b->a,c",
			"a->b;b!->c;c"}, // broke b->a

		// Reversing direction of p->s edge creates pqrs cycle.
		{"a->p,q,r,s;p->q,s,z;q->r,z;r->s,z;s->z", "p->q,z;s->p,z",
			"a->p,q,r,s;p!->z;q->r,z;r->s,z;s!->z"}, // broke p->q, s->p

		// We break all intra-SCC edges from updated nodes,
		// which may be more than necessary (e.g. a->b).
		{"a->b;b->c;c;d->a", "a->b,e;c->d",
			"a!->e;b->c;c!;d->a"}, // broke a->b, c->d
	} {
		metadata := parse(test.metadata)
		updates := parse(test.updates)

		if cycle := cyclic(metadata); cycle != "" {
			t.Errorf("initial metadata %s has cycle %s: ", format(metadata), cycle)
			continue
		}

		t.Log("initial", format(metadata))

		// Apply updates.
		// (parse doesn't have a way to express node deletions,
		// but they aren't very interesting.)
		maps.Copy(metadata, updates)

		t.Log("updated", format(metadata))

		// breakImportCycles accesses only these fields of Metadata:
		//    DepsByImpPath, ID - read
		//    DepsByPkgPath     - read, updated
		//    Errors            - updated
		breakImportCycles(metadata, updates)

		t.Log("acyclic", format(metadata))

		if cycle := cyclic(metadata); cycle != "" {
			t.Errorf("resulting metadata %s has cycle %s: ", format(metadata), cycle)
		}

		got := format(metadata)
		if got != test.want {
			t.Errorf("test.metadata=%s test.updates=%s: got=%s want=%s",
				test.metadata, test.updates, got, test.want)
		}
	}
}


================================================
FILE: gopls/internal/cache/metadata/graph.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package metadata

import (
	"cmp"
	"iter"
	"maps"
	"slices"
	"sort"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
)

// A Graph is an immutable and transitively closed graph of [Package] data.
type Graph struct {
	// Packages maps package IDs to their associated Packages.
	Packages map[PackageID]*Package

	// Each of the three maps below is an index of the pointer values held
	// by the Packages map. However, Package pointers are not generally canonical.

	// ImportedBy maps package IDs to the list of packages that import them.
	ImportedBy map[PackageID][]*Package

	// ForPackagePath maps package by their package path to their package ID.
	// Non-test packages appear before test packages, and within each of those
	// categories, packages with fewer CompiledGoFiles appear first.
	ForPackagePath map[PackagePath][]*Package

	// ForFile maps file URIs to packages, sorted by (!valid, cli, packageID).
	// A single file may belong to multiple packages due to tests packages.
	ForFile map[protocol.DocumentURI][]*Package
}

// Metadata implements the [Source] interface
func (g *Graph) Metadata(id PackageID) *Package {
	return g.Packages[id]
}

// Update creates a new Graph containing the result of applying the given
// updates to the receiver, though the receiver is not itself mutated. As a
// special case, if updates is empty, Update just returns the receiver.
//
// A nil map value is used to indicate a deletion.
func (g *Graph) Update(updates map[PackageID]*Package) *Graph {
	if len(updates) == 0 {
		// Optimization: since the graph is immutable, we can return the receiver.
		return g
	}

	// Debugging golang/go#64227, golang/vscode-go#3126:
	// Assert that the existing metadata graph is acyclic.
	if cycle := cyclic(g.Packages); cycle != "" {
		bug.Reportf("metadata is cyclic even before updates: %s", cycle)
	}
	// Assert that the updates contain no self-cycles.
	for id, mp := range updates {
		if mp != nil {
			for _, depID := range mp.DepsByPkgPath {
				if depID == id {
					bug.Reportf("self-cycle in metadata update: %s", id)
				}
			}
		}
	}

	// Copy pkgs map then apply updates.
	pkgs := make(map[PackageID]*Package, len(g.Packages))
	maps.Copy(pkgs, g.Packages)
	for id, mp := range updates {
		if mp == nil {
			delete(pkgs, id)
		} else {
			pkgs[id] = mp
		}
	}

	// Break import cycles involving updated nodes.
	breakImportCycles(pkgs, updates)

	return newGraph(pkgs)
}

// newGraph returns a new metadataGraph,
// deriving relations from the specified metadata.
func newGraph(pkgs map[PackageID]*Package) *Graph {
	// Build the import graph.
	importedBy := make(map[PackageID][]*Package)
	byPackagePath := make(map[PackagePath][]*Package)
	for _, mp := range pkgs {
		for _, depID := range mp.DepsByPkgPath {
			importedBy[depID] = append(importedBy[depID], mp)
		}
		byPackagePath[mp.PkgPath] = append(byPackagePath[mp.PkgPath], mp)
	}

	// Collect file associations.
	uriPkgs := make(map[protocol.DocumentURI][]*Package)
	for _, mp := range pkgs {
		uris := map[protocol.DocumentURI]struct{}{}
		for _, uri := range mp.CompiledGoFiles {
			uris[uri] = struct{}{}
		}
		for _, uri := range mp.GoFiles {
			uris[uri] = struct{}{}
		}
		for _, uri := range mp.OtherFiles {
			if strings.HasSuffix(string(uri), ".s") { // assembly
				uris[uri] = struct{}{}
			}
		}
		for uri := range uris {
			uriPkgs[uri] = append(uriPkgs[uri], mp)
		}
	}

	// Sort and filter file associations.
	for uri, pkgs := range uriPkgs {
		sort.Slice(pkgs, func(i, j int) bool {
			cli := IsCommandLineArguments(pkgs[i].ID)
			clj := IsCommandLineArguments(pkgs[j].ID)
			if cli != clj {
				return clj
			}

			// 2. packages appear in name order.
			return pkgs[i].ID < pkgs[j].ID
		})

		// Choose the best packages for each URI, according to the following rules:
		//  - If there are any valid real packages, choose them.
		//  - Else, choose the first valid command-line-argument package, if it exists.
		//
		// TODO(rfindley): it might be better to track all packages here, and exclude
		// them later when type checking, but this is the existing behavior.
		for i, pkg := range pkgs {
			// If we've seen *anything* prior to command-line arguments package, take
			// it. Note that pkgs[0] may itself be command-line-arguments.
			if i > 0 && IsCommandLineArguments(pkg.ID) {
				uriPkgs[uri] = pkgs[:i]
				break
			}
		}
	}

	for _, mps := range byPackagePath {
		slices.SortFunc(mps, func(a, b *Package) int {
			if (a.ForTest == "") != (b.ForTest == "") {
				if a.ForTest == "" {
					return -1
				}
				return 1
			}
			if c := cmp.Compare(len(a.CompiledGoFiles), len(b.CompiledGoFiles)); c != 0 {
				return c
			}
			return cmp.Compare(a.ID, b.ID)
		})
	}

	return &Graph{
		Packages:       pkgs,
		ImportedBy:     importedBy,
		ForPackagePath: byPackagePath,
		ForFile:        uriPkgs,
	}
}

// ReverseReflexiveTransitiveClosure returns a new mapping containing the
// metadata for the specified packages along with any package that
// transitively imports one of them, keyed by ID, including all the initial packages.
func (g *Graph) ReverseReflexiveTransitiveClosure(ids ...PackageID) map[PackageID]*Package {
	seen := make(map[PackageID]*Package)
	var visitAll func([]*Package)
	visitAll = func(pkgs []*Package) {
		for _, pkg := range pkgs {
			if seen[pkg.ID] == nil {
				seen[pkg.ID] = pkg
				visitAll(g.ImportedBy[pkg.ID])
			}
		}
	}
	var initial []*Package
	for _, id := range ids {
		if pkg := g.Packages[id]; pkg != nil {
			initial = append(initial, pkg)
		}
	}
	visitAll(initial)
	return seen
}

// ForwardReflexiveTransitiveClosure returns an iterator over the
// specified nodes and all their forward dependencies, in an arbitrary
// topological (dependencies-first) order. The order may vary.
func (g *Graph) ForwardReflexiveTransitiveClosure(ids ...PackageID) iter.Seq[*Package] {
	return func(yield func(*Package) bool) {
		seen := make(map[PackageID]bool)
		var visit func(PackageID) bool
		visit = func(id PackageID) bool {
			if !seen[id] {
				seen[id] = true
				if mp := g.Packages[id]; mp != nil {
					for _, depID := range mp.DepsByPkgPath {
						if !visit(depID) {
							return false
						}
					}
					if !yield(mp) {
						return false
					}
				}
			}
			return true
		}
		for _, id := range ids {
			visit(id)
		}
	}
}

// breakImportCycles breaks import cycles in the metadata by deleting
// Deps* edges. It modifies only metadata present in the 'updates'
// subset. This function has an internal test.
func breakImportCycles(metadata, updates map[PackageID]*Package) {
	// 'go list' should never report a cycle without flagging it
	// as such, but we're extra cautious since we're combining
	// information from multiple runs of 'go list'. Also, Bazel
	// may silently report cycles.
	cycles := detectImportCycles(metadata, updates)
	if len(cycles) > 0 {
		// There were cycles (uncommon). Break them.
		//
		// The naive way to break cycles would be to perform a
		// depth-first traversal and to detect and delete
		// cycle-forming edges as we encounter them.
		// However, we're not allowed to modify the existing
		// Metadata records, so we can only break edges out of
		// the 'updates' subset.
		//
		// Another possibility would be to delete not the
		// cycle forming edge but the topmost edge on the
		// stack whose tail is an updated node.
		// However, this would require that we retroactively
		// undo all the effects of the traversals that
		// occurred since that edge was pushed on the stack.
		//
		// We use a simpler scheme: we compute the set of cycles.
		// All cyclic paths necessarily involve at least one
		// updated node, so it is sufficient to break all
		// edges from each updated node to other members of
		// the strong component.
		//
		// This may result in the deletion of dominating
		// edges, causing some dependencies to appear
		// spuriously unreachable. Consider A <-> B -> C
		// where updates={A,B}. The cycle is {A,B} so the
		// algorithm will break both A->B and B->A, causing
		// A to no longer depend on B or C.
		//
		// But that's ok: any error in Metadata.Errors is
		// conservatively assumed by snapshot.clone to be a
		// potential import cycle error, and causes special
		// invalidation so that if B later drops its
		// cycle-forming import of A, both A and B will be
		// invalidated.
		for _, cycle := range cycles {
			cyclic := make(map[PackageID]bool)
			for _, mp := range cycle {
				cyclic[mp.ID] = true
			}
			for id := range cyclic {
				if mp := updates[id]; mp != nil {
					for path, depID := range mp.DepsByImpPath {
						if cyclic[depID] {
							delete(mp.DepsByImpPath, path)
						}
					}
					for path, depID := range mp.DepsByPkgPath {
						if cyclic[depID] {
							delete(mp.DepsByPkgPath, path)
						}
					}

					// Set m.Errors to enable special
					// invalidation logic in snapshot.clone.
					if len(mp.Errors) == 0 {
						mp.Errors = []packages.Error{{
							Msg:  "detected import cycle",
							Kind: packages.ListError,
						}}
					}
				}
			}
		}

		// double-check when debugging
		if false {
			if cycles := detectImportCycles(metadata, updates); len(cycles) > 0 {
				bug.Reportf("unbroken cycle: %v", cycles)
			}
		}
	}
}

// cyclic returns a description of a cycle,
// if the graph is cyclic, otherwise "".
func cyclic(graph map[PackageID]*Package) string {
	const (
		unvisited = 0
		visited   = 1
		onstack   = 2
	)
	color := make(map[PackageID]int)
	var visit func(id PackageID) string
	visit = func(id PackageID) string {
		switch color[id] {
		case unvisited:
			color[id] = onstack
		case onstack:
			return string(id) // cycle!
		case visited:
			return ""
		}
		if mp := graph[id]; mp != nil {
			for _, depID := range mp.DepsByPkgPath {
				if cycle := visit(depID); cycle != "" {
					return string(id) + "->" + cycle
				}
			}
		}
		color[id] = visited
		return ""
	}
	for id := range graph {
		if cycle := visit(id); cycle != "" {
			return cycle
		}
	}
	return ""
}

// detectImportCycles reports cycles in the metadata graph. It returns a new
// unordered array of all cycles (nontrivial strong components) in the
// metadata graph reachable from a non-nil 'updates' value.
func detectImportCycles(metadata, updates map[PackageID]*Package) [][]*Package {
	// We use the depth-first algorithm of Tarjan.
	// https://doi.org/10.1137/0201010
	//
	// TODO(adonovan): when we can use generics, consider factoring
	// in common with the other implementation of Tarjan (in typerefs),
	// abstracting over the node and edge representation.

	// A node wraps a Metadata with its working state.
	// (Unfortunately we can't intrude on shared Metadata.)
	type node struct {
		rep            *node
		mp             *Package
		index, lowlink int32
		scc            int8 // TODO(adonovan): opt: cram these 1.5 bits into previous word
	}
	nodes := make(map[PackageID]*node, len(metadata))
	nodeOf := func(id PackageID) *node {
		n, ok := nodes[id]
		if !ok {
			mp := metadata[id]
			if mp == nil {
				// Dangling import edge.
				// Not sure whether a go/packages driver ever
				// emits this, but create a dummy node in case.
				// Obviously it won't be part of any cycle.
				mp = &Package{ID: id}
			}
			n = &node{mp: mp}
			n.rep = n
			nodes[id] = n
		}
		return n
	}

	// find returns the canonical node decl.
	// (The nodes form a disjoint set forest.)
	var find func(*node) *node
	find = func(n *node) *node {
		rep := n.rep
		if rep != n {
			rep = find(rep)
			n.rep = rep // simple path compression (no union-by-rank)
		}
		return rep
	}

	// global state
	var (
		index int32 = 1
		stack []*node
		sccs  [][]*Package // set of nontrivial strongly connected components
	)

	// visit implements the depth-first search of Tarjan's SCC algorithm
	// Precondition: x is canonical.
	var visit func(*node)
	visit = func(x *node) {
		x.index = index
		x.lowlink = index
		index++

		stack = append(stack, x) // push
		x.scc = -1

		for _, yid := range x.mp.DepsByPkgPath {
			y := nodeOf(yid)
			// Loop invariant: x is canonical.
			y = find(y)
			if x == y {
				continue // nodes already combined (self-edges are impossible)
			}

			switch {
			case y.scc > 0:
				// y is already a collapsed SCC

			case y.scc < 0:
				// y is on the stack, and thus in the current SCC.
				if y.index < x.lowlink {
					x.lowlink = y.index
				}

			default:
				// y is unvisited; visit it now.
				visit(y)
				// Note: x and y are now non-canonical.
				x = find(x)
				if y.lowlink < x.lowlink {
					x.lowlink = y.lowlink
				}
			}
		}

		// Is x the root of an SCC?
		if x.lowlink == x.index {
			// Gather all metadata in the SCC (if nontrivial).
			var scc []*Package
			for {
				// Pop y from stack.
				i := len(stack) - 1
				y := stack[i]
				stack = stack[:i]
				if x != y || scc != nil {
					scc = append(scc, y.mp)
				}
				if x == y {
					break // complete
				}
				// x becomes y's canonical representative.
				y.rep = x
			}
			if scc != nil {
				sccs = append(sccs, scc)
			}
			x.scc = 1
		}
	}

	// Visit only the updated nodes:
	// the existing metadata graph has no cycles,
	// so any new cycle must involve an updated node.
	for id, mp := range updates {
		if mp != nil {
			if n := nodeOf(id); n.index == 0 { // unvisited
				visit(n)
			}
		}
	}

	return sccs
}


================================================
FILE: gopls/internal/cache/metadata/metadata.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The metadata package defines types and functions for working with package
// metadata, which describes Go packages and their relationships.
//
// Package metadata is loaded by gopls using go/packages, and the [Package]
// type is itself a projection and translation of data from
// go/packages.Package.
//
// Packages are assembled into an immutable [Graph]
package metadata

import (
	"go/ast"
	"go/types"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/packagesinternal"
)

// Declare explicit types for package paths, names, and IDs to ensure that we
// never use an ID where a path belongs, and vice versa. If we confused these,
// it would result in confusing errors because package IDs often look like
// package paths.
type (
	PackageID   string // go list's unique identifier for a package (e.g. "vendor/example.com/foo [vendor/example.com/bar.test]")
	PackagePath string // name used to prefix linker symbols (e.g. "vendor/example.com/foo")
	PackageName string // identifier in 'package' declaration (e.g. "foo")
	ImportPath  string // path that appears in an import declaration (e.g. "example.com/foo")
)

// Package represents package metadata retrieved from go/packages.
// The DepsBy{Imp,Pkg}Path maps do not contain self-import edges.
//
// An ad-hoc package (without go.mod or GOPATH) has its ID, PkgPath,
// and LoadDir equal to the absolute path of its directory.
type Package struct {
	ID      PackageID
	PkgPath PackagePath
	Name    PackageName

	// These fields are as defined by go/packages.Package
	GoFiles         []protocol.DocumentURI
	CompiledGoFiles []protocol.DocumentURI
	IgnoredFiles    []protocol.DocumentURI
	OtherFiles      []protocol.DocumentURI

	ForTest       PackagePath // q in a "p [q.test]" package, else ""
	TypesSizes    types.Sizes
	Errors        []packages.Error          // must be set for packages in import cycles
	DepsByImpPath map[ImportPath]PackageID  // may contain dups; empty ID => missing
	DepsByPkgPath map[PackagePath]PackageID // values are unique and non-empty
	Module        *packages.Module          // may be missing for std and cmd; see Go issue #65816.
	DepsErrors    []*packagesinternal.PackageError
	LoadDir       string // directory from which go/packages was run
	Standalone    bool   // package synthesized for a standalone file (e.g. ignore-tagged)
}

func (mp *Package) String() string { return string(mp.ID) }

// IsIntermediateTestVariant reports whether the given package is an
// intermediate test variant (ITV), e.g. "net/http [net/url.test]".
//
// An ITV has identical syntax to the regular variant, but different
// import metadata (DepsBy{Imp,Pkg}Path).
//
// Such test variants arise when an x_test package (in this case net/url_test)
// imports a package (in this case net/http) that itself imports the
// non-x_test package (in this case net/url).
//
// This is done so that the forward transitive closure of net/url_test has
// only one package for the "net/url" import.
// The ITV exists to hold the test variant import:
//
// net/url_test [net/url.test]
//
//	| "net/http" -> net/http [net/url.test]
//	| "net/url" -> net/url [net/url.test]
//	| ...
//
// net/http [net/url.test]
//
//	| "net/url" -> net/url [net/url.test]
//	| ...
//
// This restriction propagates throughout the import graph of net/http: for
// every package imported by net/http that imports net/url, there must be an
// intermediate test variant that instead imports "net/url [net/url.test]".
//
// As one can see from the example of net/url and net/http, intermediate test
// variants can result in many additional packages that are essentially (but
// not quite) identical. For this reason, we filter these variants wherever
// possible.
//
// # Why we mostly ignore intermediate test variants
//
// In projects with complicated tests, there may be a very large
// number of ITVs--asymptotically more than the number of ordinary
// variants. Since they have identical syntax, it is fine in most
// cases to ignore them since the results of analyzing the ordinary
// variant suffice. However, this is not entirely sound.
//
// Consider this package:
//
//	// p/p.go -- in all variants of p
//	package p
//	type T struct { io.Closer }
//
//	// p/p_test.go -- in test variant of p
//	package p
//	func (T) Close() error { ... }
//
// The ordinary variant "p" defines T with a Close method promoted
// from io.Closer. But its test variant "p [p.test]" defines a type T
// with a Close method from p_test.go.
//
// Now consider a package q that imports p, perhaps indirectly. Within
// it, T.Close will resolve to the first Close method:
//
//	// q/q.go -- in all variants of q
//	package q
//	import "p"
//	var _ = new(p.T).Close
//
// Let's assume p also contains this file defining an external test (xtest):
//
//	// p/p_x_test.go -- external test of p
//	package p_test
//	import ( "q"; "testing" )
//	func Test(t *testing.T) { ... }
//
// Note that q imports p, but p's xtest imports q. Now, in "q
// [p.test]", the intermediate test variant of q built for p's
// external test, T.Close resolves not to the io.Closer.Close
// interface method, but to the concrete method of T.Close
// declared in p_test.go.
//
// If we now request all references to the T.Close declaration in
// p_test.go, the result should include the reference from q's ITV.
// (It's not just methods that can be affected; fields can too, though
// it requires bizarre code to achieve.)
//
// As a matter of policy, gopls mostly ignores this subtlety,
// because to account for it would require that we type-check every
// intermediate test variant of p, of which there could be many.
// Good code doesn't rely on such trickery.
//
// Most callers of MetadataForFile set removeIntermediateTestVariants parameter
// to discard them before requesting type checking, or the products of
// type-checking such as the cross-reference index or method set index.
//
// MetadataForFile doesn't do this filtering itself because in some
// cases we need to make a reverse dependency query on the metadata
// graph, and it's important to include the rdeps of ITVs in that
// query. But the filtering of ITVs should be applied after that step,
// before type checking.
//
// In general, we should never type check an ITV.
func (mp *Package) IsIntermediateTestVariant() bool {
	return mp.ForTest != "" && mp.ForTest != mp.PkgPath && mp.ForTest+"_test" != mp.PkgPath
}

// A Source maps package IDs to metadata for the packages.
type Source interface {
	// Metadata returns the [Package] for the given package ID, or nil if it does
	// not exist.
	// TODO(rfindley): consider returning (*Metadata, bool)
	// TODO(rfindley): consider renaming this method.
	Metadata(PackageID) *Package
}

// TODO(rfindley): move the utility functions below to a util.go file.

// IsCommandLineArguments reports whether a given value denotes
// "command-line-arguments" package, which is a package with an unknown ID
// created by the go command. It can have a test variant, which is why callers
// should not check that a value equals "command-line-arguments" directly.
func IsCommandLineArguments(id PackageID) bool {
	return strings.Contains(string(id), "command-line-arguments")
}

// SortPostOrder sorts the IDs so that if x depends on y, then y appears before x.
func SortPostOrder(meta Source, ids []PackageID) {
	postorder := make(map[PackageID]int)
	order := 0
	var visit func(PackageID)
	visit = func(id PackageID) {
		if _, ok := postorder[id]; !ok {
			postorder[id] = -1 // break recursion
			if mp := meta.Metadata(id); mp != nil {
				for _, depID := range mp.DepsByPkgPath {
					visit(depID)
				}
			}
			order++
			postorder[id] = order
		}
	}
	for _, id := range ids {
		visit(id)
	}
	sort.Slice(ids, func(i, j int) bool {
		return postorder[ids[i]] < postorder[ids[j]]
	})
}

// UnquoteImportPath returns the unquoted import path of s,
// or "" if the path is not properly quoted.
func UnquoteImportPath(spec *ast.ImportSpec) ImportPath {
	path, err := strconv.Unquote(spec.Path.Value)
	if err != nil {
		return ""
	}
	return ImportPath(path)
}

// RemoveIntermediateTestVariants removes intermediate test variants, modifying
// the array. We use a pointer to a slice make it impossible to forget to use
// the result.
func RemoveIntermediateTestVariants(pmetas *[]*Package) {
	metas := *pmetas
	res := metas[:0]
	for _, mp := range metas {
		if !mp.IsIntermediateTestVariant() {
			res = append(res, mp)
		}
	}
	*pmetas = res
}

// IsValidImport returns whether from may import to.
func IsValidImport(from, to PackagePath, goList bool) bool {
	// If the metadata came from a build system other than go list
	// (e.g. bazel) it is beyond our means to compute visibility.
	if !goList {
		return true
	}
	i := strings.LastIndex(string(to), "/internal/")
	if i == -1 {
		return true
	}
	// TODO(rfindley): this looks wrong: IsCommandLineArguments is meant to
	// operate on package IDs, not package paths.
	if IsCommandLineArguments(PackageID(from)) {
		return true
	}
	// TODO(rfindley): this is wrong. mod.testx/p should not be able to
	// import mod.test/internal: https://go.dev/play/p/-Ca6P-E4V4q
	return strings.HasPrefix(string(from), string(to[:i]))
}


================================================
FILE: gopls/internal/cache/methodsets/methodsets.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package methodsets defines an incremental, serializable index of
// method-set information that allows efficient 'implements' queries
// across packages of the workspace without using the type checker.
//
// This package provides only the "global" (all workspace) search; the
// "local" search within a given package uses a different
// implementation based on type-checker data structures for a single
// package plus variants; see ../implementation.go.
// The local algorithm is more precise as it tests function-local types too.
//
// A global index of function-local types is challenging since they
// may reference other local types, for which we would need to invent
// stable names, an unsolved problem described in passing in Go issue
// 57497. The global algorithm also does not index anonymous interface
// types, even outside function bodies.
//
// Consequently, global results are not symmetric: applying the
// operation twice may not get you back where you started.
package methodsets

// DESIGN
//
// See https://go.dev/cl/452060 for a minimal exposition of the algorithm.
//
// For each method, we compute a fingerprint: a string representing
// the method name and type such that equal fingerprint strings mean
// identical method types.
//
// For efficiency, the fingerprint is reduced to a single bit
// of a uint64, so that the method set can be represented as
// the union of those method bits (a uint64 bitmask).
// Assignability thus reduces to a subset check on bitmasks
// followed by equality checks on fingerprints.
//
// In earlier experiments, using 128-bit masks instead of 64 reduced
// the number of candidates by about 2x. Using (like a Bloom filter) a
// different hash function to compute a second 64-bit mask and
// performing a second mask test reduced it by about 4x.
// Neither had much effect on the running time, presumably because a
// single 64-bit mask is quite effective. See CL 452060 for details.

import (
	"go/token"
	"go/types"
	"hash/crc32"
	"slices"
	"sync/atomic"

	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/fingerprint"
	"golang.org/x/tools/gopls/internal/util/frob"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/typesinternal"
)

// An Index records the non-empty method sets of all package-level
// types in a package in a form that permits assignability queries
// without the type checker.
type Index struct {
	pkg     gobPackage
	PkgPath metadata.PackagePath
}

// Decode decodes the given gob-encoded data as an Index.
func Decode(pkgpath metadata.PackagePath, data []byte) *Index {
	var pkg gobPackage
	packageCodec.Decode(data, &pkg)
	return &Index{pkg: pkg, PkgPath: pkgpath}
}

// Encode encodes the receiver as gob-encoded data.
func (index *Index) Encode() []byte {
	return packageCodec.Encode(index.pkg)
}

// NewIndex returns a new index of method-set information for all
// package-level types in the specified package.
func NewIndex(fset *token.FileSet, pkg *types.Package) *Index {
	return new(indexBuilder).build(fset, pkg)
}

// A Location records the extent of an identifier in byte-offset form.
//
// Conversion to protocol (UTF-16) form is done by the caller after a
// search, not during index construction.
type Location struct {
	Filename   string
	Start, End int // byte offsets
}

// A Key represents the method set of a given type in a form suitable
// to pass to the (*Index).Search method of many different Indexes.
type Key struct {
	mset *gobMethodSet // note: lacks position information
}

// KeyOf returns the search key for the method sets of a given type.
// It returns false if the type has no methods.
func KeyOf(t types.Type) (Key, bool) {
	mset := methodSetInfo(t, nil)
	if mset.Mask == 0 {
		return Key{}, false // no methods
	}
	return Key{mset}, true
}

// A Result reports a matching type or method in a method-set search.
type Result struct {
	TypeName    string   // name of the named type
	IsInterface bool     // matched type (or method) is abstract
	Location    Location // location of the type or method

	// methods only:
	PkgPath    string          // path of declaring package (may differ due to embedding)
	ObjectPath objectpath.Path // path of method within declaring package
}

// TypeRelation indicates the direction of subtyping relation,
// if any, between two types.
//
// It is a bitset, so that clients of Implementations may use
// Supertype|Subtype to request an undirected match.
type TypeRelation int8

const (
	Supertype TypeRelation = 0x1
	Subtype   TypeRelation = 0x2
)

// Search reports each type that implements (Supertype ∈ want) or is
// implemented by (Subtype ∈ want) the type that produced the search key.
//
// If method is non-nil, only that method of each type is reported.
//
// The result does not include the error.Error method.
// TODO(adonovan): give this special case a more systematic treatment.
func (index *Index) Search(key Key, want TypeRelation, method *types.Func) []Result {
	var results []Result
	for _, candidate := range index.pkg.MethodSets {
		// Test the direction of the relation.
		// The client may request either direction or both
		// (e.g. when the client is References),
		// and the Result reports each test independently;
		// both tests succeed when comparing identical
		// interface types.
		var got TypeRelation
		if want&Subtype != 0 && implements(candidate, key.mset) {
			got |= Subtype
		}
		if want&Supertype != 0 && implements(key.mset, candidate) {
			got |= Supertype
		}
		if got == 0 {
			continue
		}

		typeName := index.pkg.Strings[candidate.TypeName]
		if method == nil {
			results = append(results, Result{
				TypeName:    typeName,
				IsInterface: candidate.IsInterface,
				Location:    index.location(candidate.Posn),
			})
		} else {
			for _, m := range candidate.Methods {
				if m.ID == method.Id() {
					// Don't report error.Error among the results:
					// it has no true source location, no package,
					// and is excluded from the xrefs index.
					if m.PkgPath == 0 || m.ObjectPath == 0 {
						if m.ID != "Error" {
							panic("missing info for" + m.ID)
						}
						continue
					}

					results = append(results, Result{
						TypeName:    typeName,
						IsInterface: candidate.IsInterface,
						Location:    index.location(m.Posn),
						PkgPath:     index.pkg.Strings[m.PkgPath],
						ObjectPath:  objectpath.Path(index.pkg.Strings[m.ObjectPath]),
					})
					break
				}
			}
		}
	}
	return results
}

// implements reports whether x implements y.
func implements(x, y *gobMethodSet) bool {
	if !y.IsInterface {
		return false
	}

	// Fast path: neither method set is tricky, so all methods can
	// be compared by equality of ID and Fingerprint, and the
	// entire subset check can be done using the bit mask.
	if !x.Tricky && !y.Tricky {
		if x.Mask&y.Mask != y.Mask {
			return false // x lacks a method of interface y
		}
	}

	// At least one operand is tricky (e.g. contains a type parameter),
	// so we must used tree-based matching (unification).

	// nonmatching reports whether interface method 'my' lacks
	// a matching method in set x. (The sense is inverted for use
	// with slice.ContainsFunc below.)
	nonmatching := func(my *gobMethod) bool {
		for _, mx := range x.Methods {
			if mx.ID == my.ID {
				var match bool
				if !mx.Tricky && !my.Tricky {
					// Fast path: neither method is tricky,
					// so a string match is sufficient.
					match = mx.Sum&my.Sum == my.Sum && mx.Fingerprint == my.Fingerprint
				} else {
					match = fingerprint.Matches(mx.parse(), my.parse())
				}
				return !match
			}
		}
		return true // method of y not found in x
	}

	// Each interface method must have a match.
	// (This would be more readable with a DeMorganized
	// variant of ContainsFunc.)
	return !slices.ContainsFunc(y.Methods, nonmatching)
}

func (index *Index) location(posn gobPosition) Location {
	return Location{
		Filename: index.pkg.Strings[posn.File],
		Start:    posn.Offset,
		End:      posn.Offset + posn.Len,
	}
}

// An indexBuilder builds an index for a single package.
type indexBuilder struct {
	gobPackage
	stringIndex map[string]int
}

// build adds to the index all package-level named types of the specified package.
func (b *indexBuilder) build(fset *token.FileSet, pkg *types.Package) *Index {
	_ = b.string("") // 0 => ""

	objectPos := func(obj types.Object) gobPosition {
		posn := safetoken.StartPosition(fset, obj.Pos())
		return gobPosition{b.string(posn.Filename), posn.Offset, len(obj.Name())}
	}

	objectpathFor := new(objectpath.Encoder).For

	// setindexInfo sets the (Posn, PkgPath, ObjectPath) fields for each method declaration.
	setIndexInfo := func(m *gobMethod, method *types.Func) {
		// error.Error has empty Position, PkgPath, and ObjectPath.
		if method.Pkg() == nil {
			return
		}

		// Instantiations of generic methods don't have an
		// object path, so we use the generic.
		p, err := objectpathFor(method.Origin())
		if err != nil {
			// This should never happen for a method of a package-level type.
			// ...but it does (golang/go#70418).
			// Refine the crash into various bug reports.
			report := func() {
				bug.Reportf("missing object path for %s", method.FullName())
			}
			sig := method.Signature()
			if sig.Recv() == nil {
				report()
				return
			}
			_, named := typesinternal.ReceiverNamed(sig.Recv())
			switch {
			case named == nil:
				report()
			case sig.TypeParams().Len() > 0:
				report()
			case method.Origin() != method:
				report() // instantiated?
			case sig.RecvTypeParams().Len() > 0:
				report() // generic?
			default:
				report()
			}
			return
		}

		m.Posn = objectPos(method)
		m.PkgPath = b.string(method.Pkg().Path())
		m.ObjectPath = b.string(string(p))
	}

	// We ignore aliases, though in principle they could define a
	// struct{...}  or interface{...} type, or an instantiation of
	// a generic, that has a novel method set.
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		if tname, ok := scope.Lookup(name).(*types.TypeName); ok && !tname.IsAlias() {
			if mset := methodSetInfo(tname.Type(), setIndexInfo); mset.Mask != 0 {
				mset.TypeName = b.string(name)
				mset.Posn = objectPos(tname)
				// Only record types with non-trivial method sets.
				b.MethodSets = append(b.MethodSets, mset)
			}
		}
	}

	return &Index{
		pkg:     b.gobPackage,
		PkgPath: metadata.PackagePath(pkg.Path()),
	}
}

// string returns a small integer that encodes the string.
func (b *indexBuilder) string(s string) int {
	i, ok := b.stringIndex[s]
	if !ok {
		i = len(b.Strings)
		if b.stringIndex == nil {
			b.stringIndex = make(map[string]int)
		}
		b.stringIndex[s] = i
		b.Strings = append(b.Strings, s)
	}
	return i
}

// methodSetInfo returns the method-set fingerprint of a type.
// It calls the optional setIndexInfo function for each gobMethod.
// This is used during index construction, but not search (KeyOf),
// to store extra information.
func methodSetInfo(t types.Type, setIndexInfo func(*gobMethod, *types.Func)) *gobMethodSet {
	// For non-interface types, use *T
	// (if T is not already a pointer)
	// since it may have more methods.
	mset := types.NewMethodSet(EnsurePointer(t))

	// Convert the method set into a compact summary.
	var mask uint64
	tricky := false
	var buf []byte
	methods := make([]*gobMethod, mset.Len())
	for i := 0; i < mset.Len(); i++ {
		m := mset.At(i).Obj().(*types.Func)
		id := m.Id()
		fp, isTricky := fingerprint.Encode(m.Signature())
		if isTricky {
			tricky = true
		}
		buf = append(append(buf[:0], id...), fp...)
		sum := crc32.ChecksumIEEE(buf)
		methods[i] = &gobMethod{ID: id, Fingerprint: fp, Sum: sum, Tricky: isTricky}
		if setIndexInfo != nil {
			setIndexInfo(methods[i], m) // set Position, PkgPath, ObjectPath
		}
		mask |= 1 << uint64(((sum>>24)^(sum>>16)^(sum>>8)^sum)&0x3f)
	}
	return &gobMethodSet{
		IsInterface: types.IsInterface(t),
		Tricky:      tricky,
		Mask:        mask,
		Methods:     methods,
	}
}

// EnsurePointer wraps T in a types.Pointer if T is a named, non-interface type.
// This is useful to make sure you consider a named type's full method set.
func EnsurePointer(T types.Type) types.Type {
	if _, ok := types.Unalias(T).(*types.Named); ok && !types.IsInterface(T) {
		return types.NewPointer(T)
	}

	return T
}

// -- serial format of index --

// (The name says gob but in fact we use frob.)
var packageCodec = frob.CodecFor[gobPackage]()

// A gobPackage records the method set of each package-level type for a single package.
type gobPackage struct {
	Strings    []string // index of strings used by gobPosition.File, gobMethod.{Pkg,Object}Path
	MethodSets []*gobMethodSet
}

// A gobMethodSet records the method set of a single type.
type gobMethodSet struct {
	TypeName    int // name (string index) of the package-level type
	Posn        gobPosition
	IsInterface bool
	Tricky      bool   // at least one method is tricky; fingerprint must be parsed + unified
	Mask        uint64 // mask with 1 bit from each of methods[*].sum
	Methods     []*gobMethod
}

// A gobMethod records the name, type, and position of a single method.
type gobMethod struct {
	ID          string // (*types.Func).Id() value of method
	Fingerprint string // encoding of types as string of form "(params)(results)"
	Sum         uint32 // checksum of ID + fingerprint
	Tricky      bool   // method type contains tricky features (type params, interface types)

	// index records only (zero in KeyOf; also for index of error.Error).
	Posn       gobPosition // location of method declaration
	PkgPath    int         // path of package containing method declaration
	ObjectPath int         // object path of method relative to PkgPath

	// internal fields (not serialized)
	tree atomic.Pointer[fingerprint.Tree] // fingerprint tree, parsed on demand
}

// A gobPosition records the file, offset, and length of an identifier.
type gobPosition struct {
	File        int // index into gobPackage.Strings
	Offset, Len int // in bytes
}

// parse returns the method's parsed fingerprint tree.
// It may return a new instance or a cached one.
func (m *gobMethod) parse() fingerprint.Tree {
	ptr := m.tree.Load()
	if ptr == nil {
		tree := fingerprint.Parse(m.Fingerprint)
		ptr = &tree
		m.tree.Store(ptr) // may race; that's ok
	}
	return *ptr
}


================================================
FILE: gopls/internal/cache/mod.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"errors"
	"fmt"
	"regexp"
	"strings"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/internal/event"
)

// A ParsedModule contains the results of parsing a go.mod file.
type ParsedModule struct {
	URI         protocol.DocumentURI
	File        *modfile.File // maybe absent in case of error
	ReplaceMap  map[module.Version]module.Version
	Mapper      *protocol.Mapper
	ParseErrors []*Diagnostic
}

// ParseMod parses a go.mod file, using a cache. It may return partial results and an error.
func (s *Snapshot) ParseMod(ctx context.Context, fh file.Handle) (*ParsedModule, error) {
	uri := fh.URI()

	s.mu.Lock()
	entry, hit := s.parseModHandles.Get(uri)
	s.mu.Unlock()

	type parseModKey file.Identity
	type parseModResult struct {
		parsed *ParsedModule
		err    error
	}

	// cache miss?
	if !hit {
		promise, release := s.store.Promise(parseModKey(fh.Identity()), func(ctx context.Context, _ any) any {
			parsed, err := parseModImpl(ctx, fh)
			return parseModResult{parsed, err}
		})

		entry = promise
		s.mu.Lock()
		s.parseModHandles.Set(uri, entry, func(_, _ any) { release() })
		s.mu.Unlock()
	}

	// Await result.
	v, err := s.awaitPromise(ctx, entry)
	if err != nil {
		return nil, err
	}
	res := v.(parseModResult)
	return res.parsed, res.err
}

// parseModImpl parses the go.mod file whose name and contents are in fh.
// It may return partial results and an error.
func parseModImpl(ctx context.Context, fh file.Handle) (*ParsedModule, error) {
	_, done := event.Start(ctx, "cache.ParseMod", label.URI.Of(fh.URI()))
	defer done()

	contents, err := fh.Content()
	if err != nil {
		return nil, err
	}
	m := protocol.NewMapper(fh.URI(), contents)
	file, parseErr := modfile.Parse(fh.URI().Path(), contents, nil)
	// Attempt to convert the error to a standardized parse error.
	var parseErrors []*Diagnostic
	if parseErr != nil {
		mfErrList, ok := parseErr.(modfile.ErrorList)
		if !ok {
			return nil, fmt.Errorf("unexpected parse error type %v", parseErr)
		}
		for _, mfErr := range mfErrList {
			rng, err := m.OffsetRange(mfErr.Pos.Byte, mfErr.Pos.Byte)
			if err != nil {
				return nil, err
			}
			parseErrors = append(parseErrors, &Diagnostic{
				URI:      fh.URI(),
				Range:    rng,
				Severity: protocol.SeverityError,
				Source:   ParseError,
				Message:  mfErr.Err.Error(),
			})
		}
	}

	replaceMap := make(map[module.Version]module.Version)
	if parseErr == nil {
		for _, rep := range file.Replace {
			replaceMap[rep.Old] = rep.New
		}
	}

	return &ParsedModule{
		URI:         fh.URI(),
		Mapper:      m,
		File:        file,
		ReplaceMap:  replaceMap,
		ParseErrors: parseErrors,
	}, parseErr
}

// A ParsedWorkFile contains the results of parsing a go.work file.
type ParsedWorkFile struct {
	URI         protocol.DocumentURI
	File        *modfile.WorkFile
	Mapper      *protocol.Mapper
	ParseErrors []*Diagnostic
}

// ParseWork parses a go.work file, using a cache. It may return partial results and an error.
// TODO(adonovan): move to new work.go file.
func (s *Snapshot) ParseWork(ctx context.Context, fh file.Handle) (*ParsedWorkFile, error) {
	uri := fh.URI()

	s.mu.Lock()
	entry, hit := s.parseWorkHandles.Get(uri)
	s.mu.Unlock()

	type parseWorkKey file.Identity
	type parseWorkResult struct {
		parsed *ParsedWorkFile
		err    error
	}

	// cache miss?
	if !hit {
		handle, release := s.store.Promise(parseWorkKey(fh.Identity()), func(ctx context.Context, _ any) any {
			parsed, err := parseWorkImpl(ctx, fh)
			return parseWorkResult{parsed, err}
		})

		entry = handle
		s.mu.Lock()
		s.parseWorkHandles.Set(uri, entry, func(_, _ any) { release() })
		s.mu.Unlock()
	}

	// Await result.
	v, err := s.awaitPromise(ctx, entry)
	if err != nil {
		return nil, err
	}
	res := v.(parseWorkResult)
	return res.parsed, res.err
}

// parseWorkImpl parses a go.work file. It may return partial results and an error.
func parseWorkImpl(ctx context.Context, fh file.Handle) (*ParsedWorkFile, error) {
	_, done := event.Start(ctx, "cache.ParseWork", label.URI.Of(fh.URI()))
	defer done()

	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	m := protocol.NewMapper(fh.URI(), content)
	file, parseErr := modfile.ParseWork(fh.URI().Path(), content, nil)
	// Attempt to convert the error to a standardized parse error.
	var parseErrors []*Diagnostic
	if parseErr != nil {
		mfErrList, ok := parseErr.(modfile.ErrorList)
		if !ok {
			return nil, fmt.Errorf("unexpected parse error type %v", parseErr)
		}
		for _, mfErr := range mfErrList {
			rng, err := m.OffsetRange(mfErr.Pos.Byte, mfErr.Pos.Byte)
			if err != nil {
				return nil, err
			}
			parseErrors = append(parseErrors, &Diagnostic{
				URI:      fh.URI(),
				Range:    rng,
				Severity: protocol.SeverityError,
				Source:   ParseError,
				Message:  mfErr.Err.Error(),
			})
		}
	}
	return &ParsedWorkFile{
		URI:         fh.URI(),
		Mapper:      m,
		File:        file,
		ParseErrors: parseErrors,
	}, parseErr
}

// ModWhy returns the "go mod why" result for each module named in a
// require statement in the go.mod file.
// TODO(adonovan): move to new mod_why.go file.
func (s *Snapshot) ModWhy(ctx context.Context, fh file.Handle) (map[string]string, error) {
	uri := fh.URI()

	if s.FileKind(fh) != file.Mod {
		return nil, fmt.Errorf("%s is not a go.mod file", uri)
	}

	s.mu.Lock()
	entry, hit := s.modWhyHandles.Get(uri)
	s.mu.Unlock()

	type modWhyResult struct {
		why map[string]string
		err error
	}

	// cache miss?
	if !hit {
		handle := memoize.NewPromise("modWhy", func(ctx context.Context, arg any) any {
			why, err := modWhyImpl(ctx, arg.(*Snapshot), fh)
			return modWhyResult{why, err}
		})

		entry = handle
		s.mu.Lock()
		s.modWhyHandles.Set(uri, entry, nil)
		s.mu.Unlock()
	}

	// Await result.
	v, err := s.awaitPromise(ctx, entry)
	if err != nil {
		return nil, err
	}
	res := v.(modWhyResult)
	return res.why, res.err
}

// modWhyImpl returns the result of "go mod why -m" on the specified go.mod file.
func modWhyImpl(ctx context.Context, snapshot *Snapshot, fh file.Handle) (map[string]string, error) {
	ctx, done := event.Start(ctx, "cache.ModWhy", label.URI.Of(fh.URI()))
	defer done()

	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, err
	}
	// No requires to explain.
	if len(pm.File.Require) == 0 {
		return nil, nil // empty result
	}
	// Run `go mod why` on all the dependencies.
	args := []string{"why", "-m"}
	for _, req := range pm.File.Require {
		args = append(args, req.Mod.Path)
	}
	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(NoNetwork, fh.URI().DirPath(), "mod", args)
	if err != nil {
		return nil, err
	}
	defer cleanupInvocation()
	stdout, err := snapshot.View().GoCommandRunner().Run(ctx, *inv)
	if err != nil {
		return nil, err
	}
	whyList := strings.Split(stdout.String(), "\n\n")
	if len(whyList) != len(pm.File.Require) {
		return nil, fmt.Errorf("mismatched number of results: got %v, want %v", len(whyList), len(pm.File.Require))
	}
	why := make(map[string]string, len(pm.File.Require))
	for i, req := range pm.File.Require {
		why[req.Mod.Path] = whyList[i]
	}
	return why, nil
}

// extractGoCommandErrors tries to parse errors that come from the go command
// and shape them into go.mod diagnostics.
// TODO: rename this to 'load errors'
func (s *Snapshot) extractGoCommandErrors(ctx context.Context, goCmdError error) []*Diagnostic {
	if goCmdError == nil {
		return nil
	}

	type locatedErr struct {
		loc protocol.Location
		msg string
	}
	diagLocations := map[*ParsedModule]locatedErr{}
	backupDiagLocations := map[*ParsedModule]locatedErr{}

	// If moduleErrs is non-nil, go command errors are scoped to specific
	// modules.
	var moduleErrs *moduleErrorMap
	_ = errors.As(goCmdError, &moduleErrs)

	// Match the error against all the mod files in the workspace.
	for _, uri := range s.View().ModFiles() {
		fh, err := s.ReadFile(ctx, uri)
		if err != nil {
			event.Error(ctx, "getting modfile for Go command error", err)
			continue
		}
		pm, err := s.ParseMod(ctx, fh)
		if err != nil {
			// Parsing errors are reported elsewhere
			return nil
		}
		var msgs []string // error messages to consider
		if moduleErrs != nil {
			if pm.File.Module != nil {
				for _, mes := range moduleErrs.errs[pm.File.Module.Mod.Path] {
					msgs = append(msgs, mes.Error())
				}
			}
		} else {
			msgs = append(msgs, goCmdError.Error())
		}
		for _, msg := range msgs {
			if strings.Contains(goCmdError.Error(), "errors parsing go.mod") {
				// The go command emits parse errors for completely invalid go.mod files.
				// Those are reported by our own diagnostics and can be ignored here.
				// As of writing, we are not aware of any other errors that include
				// file/position information, so don't even try to find it.
				continue
			}
			loc, found, err := s.matchErrorToModule(pm, msg)
			if err != nil {
				event.Error(ctx, "matching error to module", err)
				continue
			}
			le := locatedErr{
				loc: loc,
				msg: msg,
			}
			if found {
				diagLocations[pm] = le
			} else {
				backupDiagLocations[pm] = le
			}
		}
	}

	// If we didn't find any good matches, assign diagnostics to all go.mod files.
	if len(diagLocations) == 0 {
		diagLocations = backupDiagLocations
	}

	var srcErrs []*Diagnostic
	for pm, le := range diagLocations {
		diag, err := s.goCommandDiagnostic(pm, le.loc, le.msg)
		if err != nil {
			event.Error(ctx, "building go command diagnostic", err)
			continue
		}
		srcErrs = append(srcErrs, diag)
	}
	return srcErrs
}

var moduleVersionInErrorRe = regexp.MustCompile(`[:\s]([+-._~0-9A-Za-z]+)@([+-._~0-9A-Za-z]+)[:\s]`)

// matchErrorToModule matches a go command error message to a go.mod file.
// Some examples:
//
//	example.com@v1.2.2: reading example.com/@v/v1.2.2.mod: no such file or directory
//	go: github.com/cockroachdb/apd/v2@v2.0.72: reading github.com/cockroachdb/apd/go.mod at revision v2.0.72: unknown revision v2.0.72
//	go: example.com@v1.2.3 requires\n\trandom.org@v1.2.3: parsing go.mod:\n\tmodule declares its path as: bob.org\n\tbut was required as: random.org
//
// It returns the location of a reference to the one of the modules and true
// if one exists. If none is found it returns a fallback location and false.
func (s *Snapshot) matchErrorToModule(pm *ParsedModule, goCmdError string) (protocol.Location, bool, error) {
	var reference *modfile.Line
	matches := moduleVersionInErrorRe.FindAllStringSubmatch(goCmdError, -1)

	for i := len(matches) - 1; i >= 0; i-- {
		ver := module.Version{Path: matches[i][1], Version: matches[i][2]}
		if err := module.Check(ver.Path, ver.Version); err != nil {
			continue
		}
		reference = findModuleReference(pm.File, ver)
		if reference != nil {
			break
		}
	}

	if reference == nil {
		// No match for the module path was found in the go.mod file.
		// Show the error on the module declaration, if one exists, or
		// just the first line of the file.
		var start, end int
		if pm.File.Module != nil && pm.File.Module.Syntax != nil {
			syntax := pm.File.Module.Syntax
			start, end = syntax.Start.Byte, syntax.End.Byte
		}
		loc, err := pm.Mapper.OffsetLocation(start, end)
		return loc, false, err
	}

	loc, err := pm.Mapper.OffsetLocation(reference.Start.Byte, reference.End.Byte)
	return loc, true, err
}

// goCommandDiagnostic creates a diagnostic for a given go command error.
func (s *Snapshot) goCommandDiagnostic(pm *ParsedModule, loc protocol.Location, goCmdError string) (*Diagnostic, error) {
	matches := moduleVersionInErrorRe.FindAllStringSubmatch(goCmdError, -1)
	var innermost *module.Version
	for i := len(matches) - 1; i >= 0; i-- {
		ver := module.Version{Path: matches[i][1], Version: matches[i][2]}
		if err := module.Check(ver.Path, ver.Version); err != nil {
			continue
		}
		innermost = &ver
		break
	}

	switch {
	case strings.Contains(goCmdError, "inconsistent vendoring"):
		cmd := command.NewVendorCommand("Run go mod vendor", command.URIArg{URI: pm.URI})
		return &Diagnostic{
			URI:      pm.URI,
			Range:    loc.Range,
			Severity: protocol.SeverityError,
			Source:   ListError,
			Message: `Inconsistent vendoring detected. Please re-run "go mod vendor".
See https://github.com/golang/go/issues/39164 for more detail on this issue.`,
			SuggestedFixes: []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)},
		}, nil

	case strings.Contains(goCmdError, "updates to go.sum needed"), strings.Contains(goCmdError, "missing go.sum entry"):
		var args []protocol.DocumentURI
		args = append(args, s.View().ModFiles()...)
		tidyCmd := command.NewTidyCommand("Run go mod tidy", command.URIArgs{URIs: args})
		updateCmd := command.NewUpdateGoSumCommand("Update go.sum", command.URIArgs{URIs: args})
		msg := "go.sum is out of sync with go.mod. Please update it by applying the quick fix."
		if innermost != nil {
			msg = fmt.Sprintf("go.sum is out of sync with go.mod: entry for %v is missing. Please updating it by applying the quick fix.", innermost)
		}
		return &Diagnostic{
			URI:      pm.URI,
			Range:    loc.Range,
			Severity: protocol.SeverityError,
			Source:   ListError,
			Message:  msg,
			SuggestedFixes: []SuggestedFix{
				SuggestedFixFromCommand(tidyCmd, protocol.QuickFix),
				SuggestedFixFromCommand(updateCmd, protocol.QuickFix),
			},
		}, nil
	case strings.Contains(goCmdError, "disabled by GOPROXY=off") && innermost != nil:
		title := fmt.Sprintf("Download %v@%v", innermost.Path, innermost.Version)
		cmd := command.NewAddDependencyCommand(title, command.DependencyArgs{
			URI:        pm.URI,
			AddRequire: false,
			GoCmdArgs:  []string{fmt.Sprintf("%v@%v", innermost.Path, innermost.Version)},
		})
		return &Diagnostic{
			URI:            pm.URI,
			Range:          loc.Range,
			Severity:       protocol.SeverityError,
			Message:        fmt.Sprintf("%v@%v has not been downloaded", innermost.Path, innermost.Version),
			Source:         ListError,
			SuggestedFixes: []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)},
		}, nil
	default:
		return &Diagnostic{
			URI:      pm.URI,
			Range:    loc.Range,
			Severity: protocol.SeverityError,
			Source:   ListError,
			Message:  goCmdError,
		}, nil
	}
}

func findModuleReference(mf *modfile.File, ver module.Version) *modfile.Line {
	for _, req := range mf.Require {
		if req.Mod == ver {
			return req.Syntax
		}
	}
	for _, ex := range mf.Exclude {
		if ex.Mod == ver {
			return ex.Syntax
		}
	}
	for _, rep := range mf.Replace {
		if rep.New == ver || rep.Old == ver {
			return rep.Syntax
		}
	}
	return nil
}

// ResolvedVersion returns the version used for a module, which considers replace directive.
func ResolvedVersion(module *packages.Module) string {
	// don't visit replace recursively as src/cmd/go/internal/modinfo/info.go
	// visits replace field only once.
	if module.Replace != nil {
		return module.Replace.Version
	}
	return module.Version
}

// ResolvedPath returns the module path, which considers replace directive.
func ResolvedPath(module *packages.Module) string {
	if module.Replace != nil {
		return module.Replace.Path
	}
	return module.Path
}

// ResolvedString returns a representation of the Version suitable for logging
// (Path@Version, or just Path if Version is empty),
// which considers replace directive.
func ResolvedString(module *packages.Module) string {
	if ResolvedVersion(module) == "" {
		ResolvedPath(module)
	}
	return ResolvedPath(module) + "@" + ResolvedVersion(module)
}


================================================
FILE: gopls/internal/cache/mod_tidy.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/token"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
)

// This error is sought by mod diagnostics.
var ErrNoModOnDisk = errors.New("go.mod file is not on disk")

// A TidiedModule contains the results of running `go mod tidy` on a module.
type TidiedModule struct {
	// Diagnostics representing changes made by `go mod tidy`.
	Diagnostics []*Diagnostic
	// The bytes of the go.mod file after it was tidied.
	TidiedContent []byte
}

// ModTidy returns the go.mod file that would be obtained by running
// "go mod tidy". Concurrent requests are combined into a single command.
func (s *Snapshot) ModTidy(ctx context.Context, pm *ParsedModule) (*TidiedModule, error) {
	ctx, done := event.Start(ctx, "cache.snapshot.ModTidy")
	defer done()

	uri := pm.URI
	if pm.File == nil {
		return nil, fmt.Errorf("cannot tidy unparsable go.mod file: %v", uri)
	}

	s.mu.Lock()
	entry, hit := s.modTidyHandles.Get(uri)
	s.mu.Unlock()

	type modTidyResult struct {
		tidied *TidiedModule
		err    error
	}

	// Cache miss?
	if !hit {
		// If the file handle is an overlay, it may not be written to disk.
		// The go.mod file has to be on disk for `go mod tidy` to work.
		// TODO(rfindley): is this still true with Go 1.16 overlay support?
		fh, err := s.ReadFile(ctx, pm.URI)
		if err != nil {
			return nil, err
		}
		if _, ok := fh.(*overlay); ok {
			if info, _ := os.Stat(uri.Path()); info == nil {
				return nil, ErrNoModOnDisk
			}
		}

		if err := s.awaitLoaded(ctx); err != nil {
			return nil, err
		}

		handle := memoize.NewPromise("modTidy", func(ctx context.Context, arg any) any {
			tidied, err := modTidyImpl(ctx, arg.(*Snapshot), pm)
			return modTidyResult{tidied, err}
		})

		entry = handle
		s.mu.Lock()
		s.modTidyHandles.Set(uri, entry, nil)
		s.mu.Unlock()
	}

	// Await result.
	v, err := s.awaitPromise(ctx, entry)
	if err != nil {
		return nil, err
	}
	res := v.(modTidyResult)
	return res.tidied, res.err
}

// modTidyImpl runs "go mod tidy" on a go.mod file.
func modTidyImpl(ctx context.Context, snapshot *Snapshot, pm *ParsedModule) (*TidiedModule, error) {
	ctx, done := event.Start(ctx, "cache.ModTidy", label.URI.Of(pm.URI))
	defer done()

	tempDir, cleanup, err := TempModDir(ctx, snapshot, pm.URI)
	if err != nil {
		return nil, err
	}
	defer cleanup()

	args := []string{"tidy", "-modfile=" + filepath.Join(tempDir, "go.mod")}
	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(NoNetwork, pm.URI.DirPath(), "mod", args, "GOWORK=off")
	if err != nil {
		return nil, err
	}
	defer cleanupInvocation()
	if _, err := snapshot.view.gocmdRunner.Run(ctx, *inv); err != nil {
		return nil, err
	}

	// Go directly to disk to get the temporary mod file,
	// since it is always on disk.
	tempMod := filepath.Join(tempDir, "go.mod")
	tempContents, err := os.ReadFile(tempMod)
	if err != nil {
		return nil, err
	}
	ideal, err := modfile.Parse(tempMod, tempContents, nil)
	if err != nil {
		// We do not need to worry about the temporary file's parse errors
		// since it has been "tidied".
		return nil, err
	}

	// Compare the original and tidied go.mod files to compute errors and
	// suggested fixes.
	diagnostics, err := modTidyDiagnostics(ctx, snapshot, pm, ideal)
	if err != nil {
		return nil, err
	}

	return &TidiedModule{
		Diagnostics:   diagnostics,
		TidiedContent: tempContents,
	}, nil
}

// modTidyDiagnostics computes the differences between the original and tidied
// go.mod files to produce diagnostic and suggested fixes. Some diagnostics
// may appear on the Go files that import packages from missing modules.
func modTidyDiagnostics(ctx context.Context, snapshot *Snapshot, pm *ParsedModule, ideal *modfile.File) (diagnostics []*Diagnostic, err error) {
	// First, determine which modules are unused and which are missing from the
	// original go.mod file.
	var (
		unused          = make(map[string]*modfile.Require, len(pm.File.Require))
		missing         = make(map[string]*modfile.Require, len(ideal.Require))
		wrongDirectness = make(map[string]*modfile.Require, len(pm.File.Require))
	)
	for _, req := range pm.File.Require {
		unused[req.Mod.Path] = req
	}
	for _, req := range ideal.Require {
		origReq := unused[req.Mod.Path]
		if origReq == nil {
			missing[req.Mod.Path] = req
			continue
		} else if origReq.Indirect != req.Indirect {
			wrongDirectness[req.Mod.Path] = origReq
		}
		delete(unused, req.Mod.Path)
	}
	for _, req := range wrongDirectness {
		// Handle dependencies that are incorrectly labeled indirect and
		// vice versa.
		srcDiag, err := directnessDiagnostic(pm.Mapper, req)
		if err != nil {
			// We're probably in a bad state if we can't compute a
			// directnessDiagnostic, but try to keep going so as to not suppress
			// other, valid diagnostics.
			event.Error(ctx, "computing directness diagnostic", err)
			continue
		}
		diagnostics = append(diagnostics, srcDiag)
	}
	// Next, compute any diagnostics for modules that are missing from the
	// go.mod file. The fixes will be for the go.mod file, but the
	// diagnostics should also appear in both the go.mod file and the import
	// statements in the Go files in which the dependencies are used.
	// Finally, add errors for any unused dependencies.
	if len(missing) > 0 {
		missingModuleDiagnostics, err := missingModuleDiagnostics(ctx, snapshot, pm, ideal, missing)
		if err != nil {
			return nil, err
		}
		diagnostics = append(diagnostics, missingModuleDiagnostics...)
	}

	// Opt: if this is the only diagnostic, we can avoid textual edits and just
	// run the Go command.
	//
	// See also the documentation for command.RemoveDependencyArgs.OnlyDiagnostic.
	onlyDiagnostic := len(diagnostics) == 0 && len(unused) == 1
	for _, req := range unused {
		srcErr, err := unusedDiagnostic(pm.Mapper, req, onlyDiagnostic)
		if err != nil {
			return nil, err
		}
		diagnostics = append(diagnostics, srcErr)
	}
	return diagnostics, nil
}

func missingModuleDiagnostics(ctx context.Context, snapshot *Snapshot, pm *ParsedModule, ideal *modfile.File, missing map[string]*modfile.Require) ([]*Diagnostic, error) {
	missingModuleFixes := map[*modfile.Require][]SuggestedFix{}
	var diagnostics []*Diagnostic
	for _, req := range missing {
		srcDiag, err := missingModuleDiagnostic(pm, req)
		if err != nil {
			return nil, err
		}
		missingModuleFixes[req] = srcDiag.SuggestedFixes
		diagnostics = append(diagnostics, srcDiag)
	}

	// Add diagnostics for missing modules anywhere they are imported in the
	// workspace.
	metas, err := snapshot.WorkspaceMetadata(ctx)
	if err != nil {
		return nil, err
	}
	// TODO(adonovan): opt: opportunities for parallelism abound.
	for _, mp := range metas {
		// Read both lists of files of this package.
		//
		// Parallelism is not necessary here as the files will have already been
		// pre-read at load time.
		goFiles, err := readFiles(ctx, snapshot, mp.GoFiles)
		if err != nil {
			return nil, err
		}
		compiledGoFiles, err := readFiles(ctx, snapshot, mp.CompiledGoFiles)
		if err != nil {
			return nil, err
		}

		missingImports := map[string]*modfile.Require{}

		// If -mod=readonly is not set we may have successfully imported
		// packages from missing modules. Otherwise they'll be in
		// MissingDependencies. Combine both.
		imps, err := parseImports(ctx, snapshot, goFiles)
		if err != nil {
			return nil, err
		}
		for imp := range imps {
			if req, ok := missing[imp]; ok {
				missingImports[imp] = req
				break
			}
			// If the import is a package of the dependency, then add the
			// package to the map, this will eliminate the need to do this
			// prefix package search on each import for each file.
			// Example:
			//
			// import (
			//   "golang.org/x/tools/internal/expect"
			//   "golang.org/x/tools/go/packages"
			// )
			// They both are related to the same module: "golang.org/x/tools".
			var match string
			for _, req := range ideal.Require {
				if strings.HasPrefix(imp, req.Mod.Path) && len(req.Mod.Path) > len(match) {
					match = req.Mod.Path
				}
			}
			if req, ok := missing[match]; ok {
				missingImports[imp] = req
			}
		}
		// None of this package's imports are from missing modules.
		if len(missingImports) == 0 {
			continue
		}
		for _, goFile := range compiledGoFiles {
			pgf, err := snapshot.ParseGo(ctx, goFile, parsego.Header)
			if err != nil {
				continue
			}
			file, m := pgf.File, pgf.Mapper
			if file == nil || m == nil {
				continue
			}
			imports := make(map[string]*ast.ImportSpec)
			for _, imp := range file.Imports {
				if imp.Path == nil {
					continue
				}
				if target, err := strconv.Unquote(imp.Path.Value); err == nil {
					imports[target] = imp
				}
			}
			if len(imports) == 0 {
				continue
			}
			for importPath, req := range missingImports {
				imp, ok := imports[importPath]
				if !ok {
					continue
				}
				fixes, ok := missingModuleFixes[req]
				if !ok {
					return nil, fmt.Errorf("no missing module fix for %q (%q)", importPath, req.Mod.Path)
				}
				srcErr, err := missingModuleForImport(pgf, imp, req, fixes)
				if err != nil {
					return nil, err
				}
				diagnostics = append(diagnostics, srcErr)
			}
		}
	}
	return diagnostics, nil
}

// unusedDiagnostic returns a Diagnostic for an unused require.
func unusedDiagnostic(m *protocol.Mapper, req *modfile.Require, onlyDiagnostic bool) (*Diagnostic, error) {
	rng, err := m.OffsetRange(req.Syntax.Start.Byte, req.Syntax.End.Byte)
	if err != nil {
		return nil, err
	}
	title := fmt.Sprintf("Remove dependency: %s", req.Mod.Path)
	cmd := command.NewRemoveDependencyCommand(title, command.RemoveDependencyArgs{
		URI:            m.URI,
		OnlyDiagnostic: onlyDiagnostic,
		ModulePath:     req.Mod.Path,
	})
	return &Diagnostic{
		URI:            m.URI,
		Range:          rng,
		Severity:       protocol.SeverityWarning,
		Source:         ModTidyError,
		Message:        fmt.Sprintf("%s is not used in this module", req.Mod.Path),
		SuggestedFixes: []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)},
	}, nil
}

// directnessDiagnostic extracts errors when a dependency is labeled indirect when
// it should be direct and vice versa.
func directnessDiagnostic(m *protocol.Mapper, req *modfile.Require) (*Diagnostic, error) {
	rng, err := m.OffsetRange(req.Syntax.Start.Byte, req.Syntax.End.Byte)
	if err != nil {
		return nil, err
	}
	direction := "indirect"
	if req.Indirect {
		direction = "direct"

		// If the dependency should be direct, just highlight the // indirect.
		if comments := req.Syntax.Comment(); comments != nil && len(comments.Suffix) > 0 {
			end := comments.Suffix[0].Start
			end.LineRune += len(comments.Suffix[0].Token)
			end.Byte += len(comments.Suffix[0].Token)
			rng, err = m.OffsetRange(comments.Suffix[0].Start.Byte, end.Byte)
			if err != nil {
				return nil, err
			}
		}
	}
	// If the dependency should be indirect, add the // indirect.
	edits, err := switchDirectness(req, m)
	if err != nil {
		return nil, err
	}
	return &Diagnostic{
		URI:      m.URI,
		Range:    rng,
		Severity: protocol.SeverityWarning,
		Source:   ModTidyError,
		Message:  fmt.Sprintf("%s should be %s", req.Mod.Path, direction),
		SuggestedFixes: []SuggestedFix{{
			Title: fmt.Sprintf("Change %s to %s", req.Mod.Path, direction),
			Edits: map[protocol.DocumentURI][]protocol.TextEdit{
				m.URI: edits,
			},
			ActionKind: protocol.QuickFix,
		}},
	}, nil
}

func missingModuleDiagnostic(pm *ParsedModule, req *modfile.Require) (*Diagnostic, error) {
	var rng protocol.Range
	// Default to the start of the file if there is no module declaration.
	if pm.File != nil && pm.File.Module != nil && pm.File.Module.Syntax != nil {
		start, end := pm.File.Module.Syntax.Span()
		var err error
		rng, err = pm.Mapper.OffsetRange(start.Byte, end.Byte)
		if err != nil {
			return nil, err
		}
	}
	title := fmt.Sprintf("Add %s to your go.mod file", req.Mod.Path)
	cmd := command.NewAddDependencyCommand(title, command.DependencyArgs{
		URI:        pm.Mapper.URI,
		AddRequire: !req.Indirect,
		GoCmdArgs:  []string{req.Mod.Path + "@" + req.Mod.Version},
	})
	return &Diagnostic{
		URI:            pm.Mapper.URI,
		Range:          rng,
		Severity:       protocol.SeverityError,
		Source:         ModTidyError,
		Message:        fmt.Sprintf("%s is not in your go.mod file", req.Mod.Path),
		SuggestedFixes: []SuggestedFix{SuggestedFixFromCommand(cmd, protocol.QuickFix)},
	}, nil
}

// switchDirectness gets the edits needed to change an indirect dependency to
// direct and vice versa.
func switchDirectness(req *modfile.Require, m *protocol.Mapper) ([]protocol.TextEdit, error) {
	// We need a private copy of the parsed go.mod file, since we're going to
	// modify it.
	copied, err := modfile.Parse("", m.Content, nil)
	if err != nil {
		return nil, err
	}
	// Change the directness in the matching require statement. To avoid
	// reordering the require statements, rewrite all of them.
	var requires []*modfile.Require
	seenVersions := make(map[string]string)
	for _, r := range copied.Require {
		if seen := seenVersions[r.Mod.Path]; seen != "" && seen != r.Mod.Version {
			// Avoid a panic in SetRequire below, which panics on conflicting
			// versions.
			return nil, fmt.Errorf("%q has conflicting versions: %q and %q", r.Mod.Path, seen, r.Mod.Version)
		}
		seenVersions[r.Mod.Path] = r.Mod.Version
		if r.Mod.Path == req.Mod.Path {
			requires = append(requires, &modfile.Require{
				Mod:      r.Mod,
				Syntax:   r.Syntax,
				Indirect: !r.Indirect,
			})
			continue
		}
		requires = append(requires, r)
	}
	copied.SetRequire(requires)
	newContent, err := copied.Format()
	if err != nil {
		return nil, err
	}
	// Calculate the edits to be made due to the change.
	edits := diff.Bytes(m.Content, newContent)
	return protocol.EditsFromDiffEdits(m, edits)
}

// missingModuleForImport creates an error for a given import path that comes
// from a missing module.
func missingModuleForImport(pgf *parsego.File, imp *ast.ImportSpec, req *modfile.Require, fixes []SuggestedFix) (*Diagnostic, error) {
	if req.Syntax == nil {
		return nil, fmt.Errorf("no syntax for %v", req)
	}
	rng, err := pgf.NodeRange(imp.Path)
	if err != nil {
		return nil, err
	}
	return &Diagnostic{
		URI:            pgf.URI,
		Range:          rng,
		Severity:       protocol.SeverityError,
		Source:         ModTidyError,
		Message:        fmt.Sprintf("%s is not in your go.mod file", req.Mod.Path),
		SuggestedFixes: fixes,
	}, nil
}

// parseImports parses the headers of the specified files and returns
// the set of strings that appear in import declarations within
// GoFiles. Errors are ignored.
//
// (We can't simply use Metadata.Imports because it is based on
// CompiledGoFiles, after cgo processing.)
//
// TODO(rfindley): this should key off ImportPath.
func parseImports(ctx context.Context, s *Snapshot, files []file.Handle) (map[string]bool, error) {
	pgfs, err := s.view.parseCache.parseFiles(ctx, token.NewFileSet(), parsego.Header, false, files...)
	if err != nil { // e.g. context cancellation
		return nil, err
	}

	seen := make(map[string]bool)
	for _, pgf := range pgfs {
		for _, spec := range pgf.File.Imports {
			path, _ := strconv.Unquote(spec.Path.Value)
			seen[path] = true
		}
	}
	return seen, nil
}


================================================
FILE: gopls/internal/cache/mod_vuln.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"fmt"
	"io"
	"os"
	"sort"
	"strings"
	"sync"

	"golang.org/x/mod/semver"
	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
	isem "golang.org/x/tools/gopls/internal/vulncheck/semver"
	"golang.org/x/vuln/scan"
)

// ModVuln returns import vulnerability analysis for the given go.mod URI.
// Concurrent requests are combined into a single command.
func (s *Snapshot) ModVuln(ctx context.Context, modURI protocol.DocumentURI) (*vulncheck.Result, error) {
	s.mu.Lock()
	entry, hit := s.modVulnHandles.Get(modURI)
	s.mu.Unlock()

	type modVuln struct {
		result *vulncheck.Result
		err    error
	}

	// Cache miss?
	if !hit {
		handle := memoize.NewPromise("modVuln", func(ctx context.Context, arg any) any {
			result, err := modVulnImpl(ctx, arg.(*Snapshot))
			return modVuln{result, err}
		})

		entry = handle
		s.mu.Lock()
		s.modVulnHandles.Set(modURI, entry, nil)
		s.mu.Unlock()
	}

	// Await result.
	v, err := s.awaitPromise(ctx, entry)
	if err != nil {
		return nil, err
	}
	res := v.(modVuln)
	return res.result, res.err
}

// GoVersionForVulnTest is an internal environment variable used in gopls
// testing to examine govulncheck behavior with a go version different
// than what `go version` returns in the system.
const GoVersionForVulnTest = "_GOPLS_TEST_VULNCHECK_GOVERSION"

// modVulnImpl queries the vulndb and reports which vulnerabilities
// apply to this snapshot. The result contains a set of packages,
// grouped by vuln ID and by module. This implements the "import-based"
// vulnerability report on go.mod files.
func modVulnImpl(ctx context.Context, snapshot *Snapshot) (*vulncheck.Result, error) {
	// TODO(hyangah): can we let 'govulncheck' take a package list
	// used in the workspace and implement this function?

	// We want to report the intersection of vulnerable packages in the vulndb
	// and packages transitively imported by this module ('go list -deps all').
	// We use snapshot.AllMetadata to retrieve the list of packages
	// as an approximation.
	//
	// TODO(hyangah): snapshot.AllMetadata is a superset of
	// `go list all` - e.g. when the workspace has multiple main modules
	// (multiple go.mod files), that can include packages that are not
	// used by this module. Vulncheck behavior with go.work is not well
	// defined. Figure out the meaning, and if we decide to present
	// the result as if each module is analyzed independently, make
	// gopls track a separate build list for each module and use that
	// information instead of snapshot.AllMetadata.
	allMeta, err := snapshot.AllMetadata(ctx)
	if err != nil {
		return nil, err
	}

	// TODO(hyangah): handle vulnerabilities in the standard library.

	// Group packages by modules since vuln db is keyed by module.
	packagesByModule := map[metadata.PackagePath][]*metadata.Package{}
	for _, mp := range allMeta {
		modulePath := metadata.PackagePath(osv.GoStdModulePath)
		if mi := mp.Module; mi != nil {
			modulePath = metadata.PackagePath(mi.Path)
		}
		packagesByModule[modulePath] = append(packagesByModule[modulePath], mp)
	}

	var (
		mu sync.Mutex
		// Keys are osv.Entry.ID
		osvs     = map[string]*osv.Entry{}
		findings []*govulncheck.Finding
	)

	goVersion := snapshot.Options().Env[GoVersionForVulnTest]
	if goVersion == "" {
		goVersion = snapshot.GoVersionString()
	}

	stdlibModule := &packages.Module{
		Path:    osv.GoStdModulePath,
		Version: goVersion,
	}

	// GOVULNDB may point the test db URI.
	db := GetEnv(snapshot, "GOVULNDB")

	var group errgroup.Group
	group.SetLimit(10) // limit govulncheck api runs
	for _, mps := range packagesByModule {
		group.Go(func() error {
			effectiveModule := stdlibModule
			if m := mps[0].Module; m != nil {
				effectiveModule = m
			}
			for effectiveModule.Replace != nil {
				effectiveModule = effectiveModule.Replace
			}
			ver := effectiveModule.Version
			if ver == "" || !isem.Valid(ver) {
				// skip invalid version strings. the underlying scan api is strict.
				return nil
			}

			// TODO(hyangah): batch these requests and add in-memory cache for efficiency.
			vulns, err := osvsByModule(ctx, db, effectiveModule.Path+"@"+ver)
			if err != nil {
				return err
			}
			if len(vulns) == 0 { // No known vulnerability.
				return nil
			}

			// set of packages in this module known to gopls.
			// This will be lazily initialized when we need it.
			var knownPkgs map[metadata.PackagePath]bool

			// Report vulnerabilities that affect packages of this module.
			for _, entry := range vulns {
				var vulnerablePkgs []*govulncheck.Finding
				fixed := fixedVersion(effectiveModule.Path, entry.Affected)

				for _, a := range entry.Affected {
					if a.Module.Ecosystem != osv.GoEcosystem || a.Module.Path != effectiveModule.Path {
						continue
					}
					for _, imp := range a.EcosystemSpecific.Packages {
						if knownPkgs == nil {
							knownPkgs = toPackagePathSet(mps)
						}
						if knownPkgs[metadata.PackagePath(imp.Path)] {
							vulnerablePkgs = append(vulnerablePkgs, &govulncheck.Finding{
								OSV:          entry.ID,
								FixedVersion: fixed,
								Trace: []*govulncheck.Frame{
									{
										Module:  effectiveModule.Path,
										Version: effectiveModule.Version,
										Package: imp.Path,
									},
								},
							})
						}
					}
				}
				if len(vulnerablePkgs) == 0 {
					continue
				}
				mu.Lock()
				osvs[entry.ID] = entry
				findings = append(findings, vulnerablePkgs...)
				mu.Unlock()
			}
			return nil
		})
	}
	if err := group.Wait(); err != nil {
		return nil, err
	}

	// Sort so the results are deterministic.
	sort.Slice(findings, func(i, j int) bool {
		x, y := findings[i], findings[j]
		if x.OSV != y.OSV {
			return x.OSV < y.OSV
		}
		return x.Trace[0].Package < y.Trace[0].Package
	})
	ret := &vulncheck.Result{
		Entries:  osvs,
		Findings: findings,
		Mode:     vulncheck.ModeImports,
	}
	return ret, nil
}

// TODO(rfindley): this function was exposed during refactoring. Reconsider it.
func GetEnv(snapshot *Snapshot, key string) string {
	val, ok := snapshot.Options().Env[key]
	if ok {
		return val
	}
	return os.Getenv(key)
}

// toPackagePathSet transforms the metadata to a set of package paths.
func toPackagePathSet(mds []*metadata.Package) map[metadata.PackagePath]bool {
	pkgPaths := make(map[metadata.PackagePath]bool, len(mds))
	for _, md := range mds {
		pkgPaths[md.PkgPath] = true
	}
	return pkgPaths
}

func fixedVersion(modulePath string, affected []osv.Affected) string {
	fixed := latestFixed(modulePath, affected)
	if fixed != "" {
		fixed = versionString(modulePath, fixed)
	}
	return fixed
}

// latestFixed returns the latest fixed version in the list of affected ranges,
// or the empty string if there are no fixed versions.
func latestFixed(modulePath string, as []osv.Affected) string {
	v := ""
	for _, a := range as {
		if a.Module.Path != modulePath {
			continue
		}
		for _, r := range a.Ranges {
			if r.Type == osv.RangeTypeSemver {
				for _, e := range r.Events {
					if e.Fixed != "" && (v == "" ||
						semver.Compare(isem.CanonicalizeSemverPrefix(e.Fixed), isem.CanonicalizeSemverPrefix(v)) > 0) {
						v = e.Fixed
					}
				}
			}
		}
	}
	return v
}

// versionString prepends a version string prefix (`v` or `go`
// depending on the modulePath) to the given semver-style version string.
func versionString(modulePath, version string) string {
	if version == "" {
		return ""
	}
	v := "v" + version
	// These are internal Go module paths used by the vuln DB
	// when listing vulns in standard library and the go command.
	if modulePath == "stdlib" || modulePath == "toolchain" {
		return semverToGoTag(v)
	}
	return v
}

// semverToGoTag returns the Go standard library repository tag corresponding
// to semver, a version string without the initial "v".
// Go tags differ from standard semantic versions in a few ways,
// such as beginning with "go" instead of "v".
func semverToGoTag(v string) string {
	if strings.HasPrefix(v, "v0.0.0") {
		return "master"
	}
	// Special case: v1.0.0 => go1.
	if v == "v1.0.0" {
		return "go1"
	}
	if !semver.IsValid(v) {
		return fmt.Sprintf("<!%s:invalid semver>", v)
	}
	goVersion := semver.Canonical(v)
	prerelease := semver.Prerelease(goVersion)
	versionWithoutPrerelease := strings.TrimSuffix(goVersion, prerelease)
	patch := strings.TrimPrefix(versionWithoutPrerelease, semver.MajorMinor(goVersion)+".")
	if patch == "0" {
		versionWithoutPrerelease = strings.TrimSuffix(versionWithoutPrerelease, ".0")
	}
	goVersion = fmt.Sprintf("go%s", strings.TrimPrefix(versionWithoutPrerelease, "v"))
	if prerelease != "" {
		// Go prereleases look like  "beta1" instead of "beta.1".
		// "beta1" is bad for sorting (since beta10 comes before beta9), so
		// require the dot form.
		i := finalDigitsIndex(prerelease)
		if i >= 1 {
			if prerelease[i-1] != '.' {
				return fmt.Sprintf("<!%s:final digits in a prerelease must follow a period>", v)
			}
			// Remove the dot.
			prerelease = prerelease[:i-1] + prerelease[i:]
		}
		goVersion += strings.TrimPrefix(prerelease, "-")
	}
	return goVersion
}

// finalDigitsIndex returns the index of the first digit in the sequence of digits ending s.
// If s doesn't end in digits, it returns -1.
func finalDigitsIndex(s string) int {
	// Assume ASCII (since the semver package does anyway).
	var i int
	for i = len(s) - 1; i >= 0; i-- {
		if s[i] < '0' || s[i] > '9' {
			break
		}
	}
	if i == len(s)-1 {
		return -1
	}
	return i + 1
}

// osvsByModule runs a govulncheck database query.
func osvsByModule(ctx context.Context, db, moduleVersion string) ([]*osv.Entry, error) {
	var args []string
	args = append(args, "-mode=query", "-json")
	if db != "" {
		args = append(args, "-db="+db)
	}
	args = append(args, moduleVersion)

	ir, iw := io.Pipe()
	handler := &osvReader{}

	var g errgroup.Group
	g.Go(func() error {
		defer iw.Close() // scan API doesn't close cmd.Stderr/cmd.Stdout.
		cmd := scan.Command(ctx, args...)
		cmd.Stdout = iw
		// TODO(hakim): Do we need to set cmd.Env = getEnvSlices(),
		// or is the process environment good enough?
		if err := cmd.Start(); err != nil {
			return err
		}
		return cmd.Wait()
	})
	g.Go(func() error {
		return govulncheck.HandleJSON(ir, handler)
	})

	if err := g.Wait(); err != nil {
		return nil, err
	}
	return handler.entry, nil
}

// osvReader implements govulncheck.Handler.
type osvReader struct {
	entry []*osv.Entry
}

func (h *osvReader) OSV(entry *osv.Entry) error {
	h.entry = append(h.entry, entry)
	return nil
}

func (h *osvReader) Config(config *govulncheck.Config) error {
	return nil
}

func (h *osvReader) Finding(finding *govulncheck.Finding) error {
	return nil
}

func (h *osvReader) Progress(progress *govulncheck.Progress) error {
	return nil
}


================================================
FILE: gopls/internal/cache/os_darwin.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"syscall"
	"unsafe"
)

func init() {
	checkPathValid = darwinCheckPathValid
}

func darwinCheckPathValid(path string) error {
	// Darwin provides fcntl(F_GETPATH) to get a path for an arbitrary FD.
	// Conveniently for our purposes, it gives the canonical case back. But
	// there's no guarantee that it will follow the same route through the
	// filesystem that the original path did.

	path, err := filepath.Abs(path)
	if err != nil {
		return err
	}
	fd, err := syscall.Open(path, os.O_RDONLY, 0)
	if err != nil {
		return err
	}
	defer syscall.Close(fd)
	buf := make([]byte, 4096) // No MAXPATHLEN in syscall, I think it's 1024, this is bigger.

	// Wheeee! syscall doesn't expose a way to call Fcntl except FcntlFlock.
	// As of writing, it just passes the pointer through, so we can just lie.
	if err := syscall.FcntlFlock(uintptr(fd), syscall.F_GETPATH, (*syscall.Flock_t)(unsafe.Pointer(&buf[0]))); err != nil {
		return err
	}
	buf = buf[:bytes.IndexByte(buf, 0)]

	isRoot := func(p string) bool {
		return p[len(p)-1] == filepath.Separator
	}
	// Darwin seems to like having multiple names for the same folder. Match as much of the suffix as we can.
	for got, want := path, string(buf); !isRoot(got) && !isRoot(want); got, want = filepath.Dir(got), filepath.Dir(want) {
		g, w := filepath.Base(got), filepath.Base(want)
		if !strings.EqualFold(g, w) {
			break
		}
		if g != w {
			return fmt.Errorf("invalid path %q: component %q is listed by macOS as %q", path, g, w)
		}
	}
	return nil
}


================================================
FILE: gopls/internal/cache/os_windows.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"fmt"
	"path/filepath"
	"syscall"
)

func init() {
	checkPathValid = windowsCheckPathValid
}

func windowsCheckPathValid(path string) error {
	// Back in the day, Windows used to have short and long filenames, and
	// it still supports those APIs. GetLongPathName gets the real case for a
	// path, so we can use it here. Inspired by
	// http://stackoverflow.com/q/2113822.

	namep, err := syscall.UTF16PtrFromString(path)
	if err != nil {
		return err
	}

	// Short paths can be longer than long paths, and unicode, so be generous.
	plenty := 4 * len(path)

	short := make([]uint16, plenty)
	n, err := syscall.GetShortPathName(namep, &short[0], uint32(len(short)))
	if err != nil {
		return err
	}
	if int(n) > len(short) {
		return fmt.Errorf("short buffer too short: %v vs %v", n, len(short))
	}

	long := make([]uint16, plenty)
	n, err = syscall.GetLongPathName(&short[0], &long[0], uint32(len(long)))
	if err != nil {
		return err
	}
	if int(n) > len(long) {
		return fmt.Errorf("long buffer too short: %v vs %v", n, len(long))
	}
	longstr := syscall.UTF16ToString(long)

	// Check that the the path -> short -> long roundtrip was idempotent.
	isRoot := func(p string) bool {
		return p[len(p)-1] == filepath.Separator
	}
	for got, want := path, longstr; !isRoot(got) && !isRoot(want); got, want = filepath.Dir(got), filepath.Dir(want) {
		if g, w := filepath.Base(got), filepath.Base(want); g != w {
			return fmt.Errorf("invalid path %q: component %q is listed by Windows as %q", path, g, w)
		}
	}
	return nil
}


================================================
FILE: gopls/internal/cache/package.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"fmt"
	"go/ast"
	"go/scanner"
	"go/token"
	"go/types"
	"slices"
	"sync"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/methodsets"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/testfuncs"
	"golang.org/x/tools/gopls/internal/cache/xrefs"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// Convenient aliases for very heavily used types.
type (
	PackageID   = metadata.PackageID
	PackagePath = metadata.PackagePath
	PackageName = metadata.PackageName
	ImportPath  = metadata.ImportPath
)

// A Package is the union of package metadata and type checking results.
//
// TODO(rfindley): for now, we do not persist the post-processing of
// loadDiagnostics, because the value of the snapshot.packages map is just the
// package handle. Fix this.
type Package struct {
	metadata        *metadata.Package
	loadDiagnostics []*Diagnostic
	pkg             *syntaxPackage
}

// syntaxPackage contains parse trees and type information for a package.
type syntaxPackage struct {
	// -- identifiers --
	id PackageID

	// -- outputs --
	fset            *token.FileSet // for now, same as the snapshot's FileSet
	goFiles         []*parsego.File
	compiledGoFiles []*parsego.File
	diagnostics     []*Diagnostic
	parseErrors     []scanner.ErrorList
	typeErrors      []types.Error
	types           *types.Package
	typesInfo       *types.Info
	typesSizes      types.Sizes
	importMap       map[PackagePath]*types.Package

	xrefsOnce sync.Once
	_xrefs    []byte // only used by the xrefs method

	methodsetsOnce sync.Once
	_methodsets    *methodsets.Index // only used by the methodsets method

	testsOnce sync.Once
	_tests    *testfuncs.Index // only used by the tests method
}

func (p *syntaxPackage) xrefs() []byte {
	p.xrefsOnce.Do(func() {
		p._xrefs = xrefs.Index(p.compiledGoFiles, p.types, p.typesInfo)
	})
	return p._xrefs
}

func (p *syntaxPackage) methodsets() *methodsets.Index {
	p.methodsetsOnce.Do(func() {
		p._methodsets = methodsets.NewIndex(p.fset, p.types)
	})
	return p._methodsets
}

func (p *syntaxPackage) tests() *testfuncs.Index {
	p.testsOnce.Do(func() {
		p._tests = testfuncs.NewIndex(p.compiledGoFiles, p.typesInfo)
	})
	return p._tests
}

// hasFixedFiles reports whether there are any 'fixed' compiled go files in the
// package.
//
// Intended to be used to refine bug reports.
func (p *syntaxPackage) hasFixedFiles() bool {
	return slices.ContainsFunc(p.compiledGoFiles, (*parsego.File).Fixed)
}

func (p *Package) String() string { return string(p.metadata.ID) }

func (p *Package) Metadata() *metadata.Package { return p.metadata }

// A loadScope defines a package loading scope for use with go/packages.
//
// TODO(rfindley): move this to load.go.
type loadScope interface {
	aScope()
}

// TODO(rfindley): move to load.go
type (
	fileLoadScope    protocol.DocumentURI // load packages containing a file (including command-line-arguments)
	packageLoadScope string               // load a specific package (the value is its PackageID)
	moduleLoadScope  struct {
		dir        string // dir containing the go.mod file
		modulePath string // parsed module path
	}
	viewLoadScope struct{} // load the workspace
)

// Implement the loadScope interface.
func (fileLoadScope) aScope()    {}
func (packageLoadScope) aScope() {}
func (moduleLoadScope) aScope()  {}
func (viewLoadScope) aScope()    {}

func (p *Package) CompiledGoFiles() []*parsego.File {
	return p.pkg.compiledGoFiles
}

func (p *Package) File(uri protocol.DocumentURI) (*parsego.File, error) {
	return p.pkg.File(uri)
}

// FileEnclosing returns the file of pkg that encloses the specified position,
// which must be mapped by p.FileSet().
func (p *Package) FileEnclosing(pos token.Pos) (*parsego.File, error) {
	for _, files := range [...][]*parsego.File{p.pkg.compiledGoFiles, p.pkg.goFiles} {
		for _, pgf := range files {
			if pgf.File.FileStart <= pos && pos <= pgf.File.FileEnd {
				return pgf, nil
			}
		}
	}
	return nil, fmt.Errorf("no parsed file for position %d (%s) in %v",
		pos, safetoken.StartPosition(p.FileSet(), pos), p.pkg.id)
}

func (pkg *syntaxPackage) File(uri protocol.DocumentURI) (*parsego.File, error) {
	for _, files := range [...][]*parsego.File{pkg.compiledGoFiles, pkg.goFiles} {
		for _, pgf := range files {
			if pgf.URI == uri {
				return pgf, nil
			}
		}
	}
	return nil, fmt.Errorf("no parsed file for %s in %v", uri, pkg.id)
}

// Syntax returns parsed compiled Go files contained in this package.
func (p *Package) Syntax() []*ast.File {
	var syntax []*ast.File
	for _, pgf := range p.pkg.compiledGoFiles {
		syntax = append(syntax, pgf.File)
	}
	return syntax
}

// FileSet returns the FileSet describing this package's positions.
//
// The returned FileSet is guaranteed to describe all Syntax, but may also
// describe additional files.
func (p *Package) FileSet() *token.FileSet {
	return p.pkg.fset
}

// Types returns the type checked go/types.Package.
func (p *Package) Types() *types.Package {
	return p.pkg.types
}

// TypesInfo returns the go/types.Info annotating the Syntax of this package
// with type information.
//
// All fields in the resulting Info are populated.
func (p *Package) TypesInfo() *types.Info {
	return p.pkg.typesInfo
}

// TypesSizes returns the sizing function used for types in this package.
func (p *Package) TypesSizes() types.Sizes {
	return p.pkg.typesSizes
}

// DependencyTypes returns the type checker's symbol for the specified
// package. It returns nil if path is not among the transitive
// dependencies of p, or if no symbols from that package were
// referenced during the type-checking of p.
func (p *Package) DependencyTypes(path PackagePath) *types.Package {
	return p.pkg.importMap[path]
}

// ParseErrors returns a slice containing all non-empty parse errors produces
// while parsing p.Syntax, or nil if the package contains no parse errors.
func (p *Package) ParseErrors() []scanner.ErrorList {
	return p.pkg.parseErrors
}

// TypeErrors returns the go/types.Errors produced during type checking this
// package, if any.
func (p *Package) TypeErrors() []types.Error {
	return p.pkg.typeErrors
}


================================================
FILE: gopls/internal/cache/parse.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"fmt"
	"go/parser"
	"go/token"
	"path/filepath"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
)

// ParseGo parses the file whose contents are provided by fh.
// The resulting tree may have been fixed up.
// If the file is not available, returns nil and an error.
func (s *Snapshot) ParseGo(ctx context.Context, fh file.Handle, mode parser.Mode) (*parsego.File, error) {
	pgfs, err := s.view.parseCache.parseFiles(ctx, token.NewFileSet(), mode, false, fh)
	if err != nil {
		return nil, err
	}
	return pgfs[0], nil
}

// parseGoImpl parses the Go source file whose content is provided by fh.
func parseGoImpl(ctx context.Context, fset *token.FileSet, fh file.Handle, mode parser.Mode, purgeFuncBodies bool) (*parsego.File, error) {
	ext := filepath.Ext(fh.URI().Path())
	if ext != ".go" && ext != "" { // files generated by cgo have no extension
		return nil, fmt.Errorf("cannot parse non-Go file %s", fh.URI())
	}
	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	// Check for context cancellation before actually doing the parse.
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	pgf, _ := parsego.Parse(ctx, fset, fh.URI(), content, mode, purgeFuncBodies) // ignore 'fixes'
	return pgf, nil
}


================================================
FILE: gopls/internal/cache/parse_cache.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"container/heap"
	"context"
	"fmt"
	"go/parser"
	"go/token"
	"math/bits"
	"runtime"
	"sync"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/memoize"
)

// This file contains an implementation of an LRU parse cache, that offsets the
// base token.Pos value of each cached file so that they may be later described
// by a single dedicated FileSet.
//
// This is achieved by tracking a monotonic offset in the token.Pos space, that
// is incremented before parsing allow room for the resulting parsed file.

// reservedForParsing defines the room in the token.Pos space reserved for
// cached parsed files.
//
// Files parsed through the parseCache are guaranteed not to have overlapping
// spans: the parseCache tracks a monotonic base for newly parsed files.
//
// By offsetting the initial base of a FileSet, we can allow other operations
// accepting the FileSet (such as the gcimporter) to add new files using the
// normal FileSet APIs without overlapping with cached parsed files.
//
// Note that 1<<60 represents an exabyte of parsed data, more than any gopls
// process can ever parse.
//
// On 32-bit systems we don't cache parse results (see parseFiles).
const reservedForParsing = 1 << (bits.UintSize - 4)

// fileSetWithBase returns a new token.FileSet with Base() equal to the
// requested base.
//
// If base < 1, fileSetWithBase panics.
// (1 is the smallest permitted FileSet base).
func fileSetWithBase(base int) *token.FileSet {
	fset := token.NewFileSet()
	if base > 1 {
		// Add a dummy file to set the base of fset. We won't ever use the
		// resulting FileSet, so it doesn't matter how we achieve this.
		//
		// FileSets leave a 1-byte padding between files, so we set the base by
		// adding a zero-length file at base-1.
		fset.AddFile("", base-1, 0)
	}
	if fset.Base() != base {
		panic("unexpected FileSet.Base")
	}
	return fset
}

const (
	// Always keep 100 recent files, independent of their wall-clock age, to
	// optimize the case where the user resumes editing after a delay.
	parseCacheMinFiles = 100
)

// parsePadding is additional padding allocated to allow for increases in
// length (such as appending missing braces) caused by fixAST.
//
// This is used to mitigate a chicken and egg problem: we must know the base
// offset of the file we're about to parse, before we start parsing, and yet
// src fixups may affect the actual size of the parsed content (and therefore
// the offsets of subsequent files).
//
// When we encounter a file that no longer fits in its allocated space in the
// fileset, we have no choice but to re-parse it. Leaving a generous padding
// reduces the likelihood of this "slow path".
//
// This value is mutable for testing, so that we can exercise the slow path.
var parsePadding = 1000 // mutable for testing

// A parseCache holds recently accessed parsed Go files. After new files are
// stored, older files may be evicted from the cache via garbage collection.
//
// The parseCache.parseFiles method exposes a batch API for parsing (and
// caching) multiple files. This is necessary for type-checking, where files
// must be parsed in a common fileset.
type parseCache struct {
	expireAfter time.Duration // interval at which to collect expired cache entries
	done        chan struct{} // closed when GC is stopped

	mu       sync.Mutex
	m        map[parseKey]*parseCacheEntry
	lru      queue  // min-atime priority queue of *parseCacheEntry
	clock    uint64 // clock time, incremented when the cache is updated
	nextBase int    // base offset for the next parsed file
}

// newParseCache creates a new parse cache and starts a goroutine to garbage
// collect entries whose age is at least expireAfter.
//
// Callers must call parseCache.stop when the parse cache is no longer in use.
func newParseCache(expireAfter time.Duration) *parseCache {
	c := &parseCache{
		expireAfter: expireAfter,
		m:           make(map[parseKey]*parseCacheEntry),
		done:        make(chan struct{}),
	}
	go c.gc()
	return c
}

// stop causes the GC goroutine to exit.
func (c *parseCache) stop() {
	close(c.done)
}

// parseKey uniquely identifies a parsed Go file.
type parseKey struct {
	uri             protocol.DocumentURI
	mode            parser.Mode
	purgeFuncBodies bool
}

type parseCacheEntry struct {
	key      parseKey
	hash     file.Hash
	promise  *memoize.Promise // memoize.Promise[*parsego.File]
	atime    uint64           // clock time of last access, for use in LRU sorting
	walltime time.Time        // actual time of last access, for use in time-based eviction; too coarse for LRU on some systems
	lruIndex int              // owned by the queue implementation
}

// startParse prepares a parsing pass, creating new promises in the cache for
// any cache misses.
//
// The resulting slice has an entry for every given file handle, though some
// entries may be nil if there was an error reading the file (in which case the
// resulting error will be non-nil).
func (c *parseCache) startParse(mode parser.Mode, purgeFuncBodies bool, fhs ...file.Handle) ([]*memoize.Promise, error) {
	c.mu.Lock()
	defer c.mu.Unlock()

	// Any parsing pass increments the clock, as we'll update access times.
	// (technically, if fhs is empty this isn't necessary, but that's a degenerate case).
	//
	// All entries parsed from a single call get the same access time.
	c.clock++
	walltime := time.Now()

	// Read file data and collect cacheable files.
	var (
		data           = make([][]byte, len(fhs)) // file content for each readable file
		promises       = make([]*memoize.Promise, len(fhs))
		firstReadError error // first error from fh.Read, or nil
	)
	for i, fh := range fhs {
		content, err := fh.Content()
		if err != nil {
			if firstReadError == nil {
				firstReadError = err
			}
			continue
		}
		data[i] = content

		key := parseKey{
			uri:             fh.URI(),
			mode:            mode,
			purgeFuncBodies: purgeFuncBodies,
		}

		if e, ok := c.m[key]; ok {
			if e.hash == fh.Identity().Hash { // cache hit
				e.atime = c.clock
				e.walltime = walltime
				heap.Fix(&c.lru, e.lruIndex)
				promises[i] = e.promise
				continue
			} else {
				// A cache hit, for a different version. Delete it.
				delete(c.m, e.key)
				heap.Remove(&c.lru, e.lruIndex)
			}
		}

		uri := fh.URI()
		promise := memoize.NewPromise("parseCache.parse", func(ctx context.Context, _ any) any {
			// Allocate 2*len(content)+parsePadding to allow for re-parsing once
			// inside of parseGoSrc without exceeding the allocated space.
			base, nextBase := c.allocateSpace(2*len(content) + parsePadding)

			pgf, fixes1 := parsego.Parse(ctx, fileSetWithBase(base), uri, content, mode, purgeFuncBodies)
			file := pgf.Tok
			if file.Base()+file.Size()+1 > nextBase {
				// The parsed file exceeds its allocated space, likely due to multiple
				// passes of src fixing. In this case, we have no choice but to re-do
				// the operation with the correct size.
				//
				// Even though the final successful parse requires only file.Size()
				// bytes of Pos space, we need to accommodate all the missteps to get
				// there, as parseGoSrc will repeat them.
				actual := file.Base() + file.Size() - base // actual size consumed, after re-parsing
				base2, nextBase2 := c.allocateSpace(actual)
				pgf2, fixes2 := parsego.Parse(ctx, fileSetWithBase(base2), uri, content, mode, purgeFuncBodies)

				// In golang/go#59097 we observed that this panic condition was hit.
				// One bug was found and fixed, but record more information here in
				// case there is still a bug here.
				if end := pgf2.Tok.Base() + pgf2.Tok.Size(); end != nextBase2-1 {
					var errBuf bytes.Buffer
					fmt.Fprintf(&errBuf, "internal error: non-deterministic parsing result:\n")
					fmt.Fprintf(&errBuf, "\t%q (%d-%d) does not span %d-%d\n", uri, pgf2.Tok.Base(), base2, end, nextBase2-1)
					fmt.Fprintf(&errBuf, "\tfirst %q (%d-%d)\n", pgf.URI, pgf.Tok.Base(), pgf.Tok.Base()+pgf.Tok.Size())
					fmt.Fprintf(&errBuf, "\tfirst space: (%d-%d), second space: (%d-%d)\n", base, nextBase, base2, nextBase2)
					fmt.Fprintf(&errBuf, "\tfirst mode: %v, second mode: %v", pgf.Mode, pgf2.Mode)
					fmt.Fprintf(&errBuf, "\tfirst err: %v, second err: %v", pgf.ParseErr, pgf2.ParseErr)
					fmt.Fprintf(&errBuf, "\tfirst fixes: %v, second fixes: %v", fixes1, fixes2)
					panic(errBuf.String())
				}
				pgf = pgf2
			}
			return pgf
		})
		promises[i] = promise

		// add new entry; entries are gc'ed asynchronously
		e := &parseCacheEntry{
			key:      key,
			hash:     fh.Identity().Hash,
			promise:  promise,
			atime:    c.clock,
			walltime: walltime,
		}
		c.m[e.key] = e
		heap.Push(&c.lru, e)
	}

	if len(c.m) != len(c.lru) {
		panic("map and LRU are inconsistent")
	}

	return promises, firstReadError
}

func (c *parseCache) gc() {
	const period = 10 * time.Second // gc period
	timer := time.NewTicker(period)
	defer timer.Stop()

	for {
		select {
		case <-c.done:
			return
		case <-timer.C:
		}

		c.gcOnce()
	}
}

func (c *parseCache) gcOnce() {
	now := time.Now()
	c.mu.Lock()
	defer c.mu.Unlock()

	for len(c.m) > parseCacheMinFiles {
		e := heap.Pop(&c.lru).(*parseCacheEntry)
		if now.Sub(e.walltime) >= c.expireAfter {
			delete(c.m, e.key)
		} else {
			heap.Push(&c.lru, e)
			break
		}
	}
}

// allocateSpace reserves the next n bytes of token.Pos space in the
// cache.
//
// It returns the resulting file base, next base, and an offset FileSet to use
// for parsing.
func (c *parseCache) allocateSpace(size int) (int, int) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if c.nextBase == 0 {
		// FileSet base values must be at least 1.
		c.nextBase = 1
	}
	base := c.nextBase
	c.nextBase += size + 1
	return base, c.nextBase
}

// parseFiles returns a parsego.File for each file handle in fhs, in the
// requested parse mode.
//
// For parsed files that already exists in the cache, access time will be
// updated. For others, parseFiles will parse and store as many results in the
// cache as space allows.
//
// The token.File for each resulting parsed file will be added to the provided
// FileSet, using the tokeninternal.AddExistingFiles API. Consequently, the
// given fset should only be used in other APIs if its base is >=
// reservedForParsing.
//
// If parseFiles returns an error, it still returns a slice,
// but with a nil entry for each file that could not be parsed.
func (c *parseCache) parseFiles(ctx context.Context, fset *token.FileSet, mode parser.Mode, purgeFuncBodies bool, fhs ...file.Handle) ([]*parsego.File, error) {
	pgfs := make([]*parsego.File, len(fhs))

	// Temporary fall-back for 32-bit systems, where reservedForParsing is too
	// small to be viable. We don't actually support 32-bit systems, so this
	// workaround is only for tests and can be removed when we stop running
	// 32-bit TryBots for gopls.
	if bits.UintSize == 32 {
		for i, fh := range fhs {
			var err error
			pgfs[i], err = parseGoImpl(ctx, fset, fh, mode, purgeFuncBodies)
			if err != nil {
				return pgfs, err
			}
		}
		return pgfs, nil
	}

	promises, firstErr := c.startParse(mode, purgeFuncBodies, fhs...)

	// Await all parsing.
	var g errgroup.Group
	g.SetLimit(runtime.GOMAXPROCS(-1)) // parsing is CPU-bound.
	for i, promise := range promises {
		if promise == nil {
			continue
		}
		i := i
		promise := promise
		g.Go(func() error {
			result, err := promise.Get(ctx, nil)
			if err != nil {
				return err
			}
			pgfs[i] = result.(*parsego.File)
			return nil
		})
	}

	if err := g.Wait(); err != nil && firstErr == nil {
		firstErr = err
	}

	// Augment the FileSet to map all parsed files.
	var tokenFiles []*token.File
	for _, pgf := range pgfs {
		if pgf == nil {
			continue
		}
		tokenFiles = append(tokenFiles, pgf.Tok)
	}
	fset.AddExistingFiles(tokenFiles...)

	const debugIssue59080 = true
	if debugIssue59080 {
		for _, f := range tokenFiles {
			pos := token.Pos(f.Base())
			f2 := fset.File(pos)
			if f2 != f {
				panic(fmt.Sprintf("internal error: File(%d (start)) = %v, not %v", pos, f2, f))
			}
			pos = token.Pos(f.Base() + f.Size())
			f2 = fset.File(pos)
			if f2 != f {
				panic(fmt.Sprintf("internal error: File(%d (end)) = %v, not %v", pos, f2, f))
			}
		}
	}

	return pgfs, firstErr
}

// -- priority queue boilerplate --

// queue is a min-atime priority queue of cache entries.
type queue []*parseCacheEntry

func (q queue) Len() int { return len(q) }

func (q queue) Less(i, j int) bool { return q[i].atime < q[j].atime }

func (q queue) Swap(i, j int) {
	q[i], q[j] = q[j], q[i]
	q[i].lruIndex = i
	q[j].lruIndex = j
}

func (q *queue) Push(x any) {
	e := x.(*parseCacheEntry)
	e.lruIndex = len(*q)
	*q = append(*q, e)
}

func (q *queue) Pop() any {
	last := len(*q) - 1
	e := (*q)[last]
	(*q)[last] = nil // aid GC
	*q = (*q)[:last]
	return e
}


================================================
FILE: gopls/internal/cache/parse_cache_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"fmt"
	"go/token"
	"math/bits"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

func skipIfNoParseCache(t *testing.T) {
	if bits.UintSize == 32 {
		t.Skip("the parse cache is not supported on 32-bit systems")
	}
}

func TestParseCache(t *testing.T) {
	skipIfNoParseCache(t)

	ctx := context.Background()
	uri := protocol.DocumentURI("file:///myfile")
	fh := makeFakeFileHandle(uri, []byte("package p\n\nconst _ = \"foo\""))
	fset := token.NewFileSet()

	cache := newParseCache(0)
	pgfs1, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh)
	if err != nil {
		t.Fatal(err)
	}
	pgf1 := pgfs1[0]
	pgfs2, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh)
	pgf2 := pgfs2[0]
	if err != nil {
		t.Fatal(err)
	}
	if pgf1 != pgf2 {
		t.Errorf("parseFiles(%q): unexpected cache miss on repeated call", uri)
	}

	// Fill up the cache with other files, but don't evict the file above.
	cache.gcOnce()
	files := []file.Handle{fh}
	files = append(files, dummyFileHandles(parseCacheMinFiles-1)...)

	pgfs3, err := cache.parseFiles(ctx, fset, parsego.Full, false, files...)
	if err != nil {
		t.Fatal(err)
	}
	pgf3 := pgfs3[0]
	if pgf3 != pgf1 {
		t.Errorf("parseFiles(%q, ...): unexpected cache miss", uri)
	}
	if pgf3.Tok.Base() != pgf1.Tok.Base() || pgf3.Tok.Size() != pgf1.Tok.Size() {
		t.Errorf("parseFiles(%q, ...): result.Tok has base: %d, size: %d, want (%d, %d)", uri, pgf3.Tok.Base(), pgf3.Tok.Size(), pgf1.Tok.Base(), pgf1.Tok.Size())
	}
	if tok := fset.File(token.Pos(pgf3.Tok.Base())); tok != pgf3.Tok {
		t.Errorf("parseFiles(%q, ...): result.Tok not contained in FileSet", uri)
	}

	// Now overwrite the cache, after which we should get new results.
	cache.gcOnce()
	files = dummyFileHandles(parseCacheMinFiles)
	_, err = cache.parseFiles(ctx, fset, parsego.Full, false, files...)
	if err != nil {
		t.Fatal(err)
	}
	// force a GC, which should collect the recently parsed files
	cache.gcOnce()
	pgfs4, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh)
	if err != nil {
		t.Fatal(err)
	}
	if pgfs4[0] == pgf1 {
		t.Errorf("parseFiles(%q): unexpected cache hit after overwriting cache", uri)
	}
}

func TestParseCache_Reparsing(t *testing.T) {
	skipIfNoParseCache(t)

	defer func(padding int) {
		parsePadding = padding
	}(parsePadding)
	parsePadding = 0

	files := dummyFileHandles(parseCacheMinFiles)
	danglingSelector := []byte("package p\nfunc _() {\n\tx.\n}")
	files = append(files, makeFakeFileHandle("file:///bad1", danglingSelector))
	files = append(files, makeFakeFileHandle("file:///bad2", danglingSelector))

	// Parsing should succeed even though we overflow the padding.
	cache := newParseCache(0)
	_, err := cache.parseFiles(context.Background(), token.NewFileSet(), parsego.Full, false, files...)
	if err != nil {
		t.Fatal(err)
	}
}

// Re-parsing the first file should not panic.
func TestParseCache_Issue59097(t *testing.T) {
	skipIfNoParseCache(t)

	defer func(padding int) {
		parsePadding = padding
	}(parsePadding)
	parsePadding = 0

	danglingSelector := []byte("package p\nfunc _() {\n\tx.\n}")
	files := []file.Handle{makeFakeFileHandle("file:///bad", danglingSelector)}

	// Parsing should succeed even though we overflow the padding.
	cache := newParseCache(0)
	_, err := cache.parseFiles(context.Background(), token.NewFileSet(), parsego.Full, false, files...)
	if err != nil {
		t.Fatal(err)
	}
}

func TestParseCache_TimeEviction(t *testing.T) {
	skipIfNoParseCache(t)

	ctx := context.Background()
	fset := token.NewFileSet()
	uri := protocol.DocumentURI("file:///myfile")
	fh := makeFakeFileHandle(uri, []byte("package p\n\nconst _ = \"foo\""))

	const gcDuration = 10 * time.Millisecond
	cache := newParseCache(gcDuration)
	cache.stop() // we'll manage GC manually, for testing.

	pgfs0, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh, fh)
	if err != nil {
		t.Fatal(err)
	}

	files := dummyFileHandles(parseCacheMinFiles)
	_, err = cache.parseFiles(ctx, fset, parsego.Full, false, files...)
	if err != nil {
		t.Fatal(err)
	}

	// Even after filling up the 'min' files, we get a cache hit for our original file.
	pgfs1, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh, fh)
	if err != nil {
		t.Fatal(err)
	}

	if pgfs0[0] != pgfs1[0] {
		t.Errorf("before GC, got unexpected cache miss")
	}

	// But after GC, we get a cache miss.
	_, err = cache.parseFiles(ctx, fset, parsego.Full, false, files...) // mark dummy files as newer
	if err != nil {
		t.Fatal(err)
	}
	time.Sleep(gcDuration)
	cache.gcOnce()

	pgfs2, err := cache.parseFiles(ctx, fset, parsego.Full, false, fh, fh)
	if err != nil {
		t.Fatal(err)
	}

	if pgfs0[0] == pgfs2[0] {
		t.Errorf("after GC, got unexpected cache hit for %s", pgfs0[0].URI)
	}
}

func TestParseCache_Duplicates(t *testing.T) {
	skipIfNoParseCache(t)

	ctx := context.Background()
	uri := protocol.DocumentURI("file:///myfile")
	fh := makeFakeFileHandle(uri, []byte("package p\n\nconst _ = \"foo\""))

	cache := newParseCache(0)
	pgfs, err := cache.parseFiles(ctx, token.NewFileSet(), parsego.Full, false, fh, fh)
	if err != nil {
		t.Fatal(err)
	}
	if pgfs[0] != pgfs[1] {
		t.Errorf("parseFiles(fh, fh): = [%p, %p], want duplicate files", pgfs[0].File, pgfs[1].File)
	}
}

func dummyFileHandles(n int) []file.Handle {
	var fhs []file.Handle
	for i := range n {
		uri := protocol.DocumentURI(fmt.Sprintf("file:///_%d", i))
		src := fmt.Appendf(nil, "package p\nvar _ = %d", i)
		fhs = append(fhs, makeFakeFileHandle(uri, src))
	}
	return fhs
}

func makeFakeFileHandle(uri protocol.DocumentURI, src []byte) fakeFileHandle {
	return fakeFileHandle{
		uri:  uri,
		data: src,
		hash: file.HashOf(src),
	}
}

type fakeFileHandle struct {
	file.Handle
	uri  protocol.DocumentURI
	data []byte
	hash file.Hash
}

func (h fakeFileHandle) String() string {
	return h.uri.Path()
}

func (h fakeFileHandle) URI() protocol.DocumentURI {
	return h.uri
}

func (h fakeFileHandle) Content() ([]byte, error) {
	return h.data, nil
}

func (h fakeFileHandle) Identity() file.Identity {
	return file.Identity{
		URI:  h.uri,
		Hash: h.hash,
	}
}


================================================
FILE: gopls/internal/cache/parsego/file.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package parsego

import (
	"go/ast"
	"go/parser"
	"go/scanner"
	"go/token"
	"sync"
	"unicode"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// A File contains the results of parsing a Go file.
type File struct {
	URI  protocol.DocumentURI
	Mode parser.Mode

	// File is the file resulting from parsing. It is always non-nil.
	//
	// Clients must not access the AST's legacy ast.Object-related
	// fields without first ensuring that [File.Resolve] was
	// already called.
	File *ast.File
	Tok  *token.File
	// Source code used to build the AST. It may be different from the
	// actual content of the file if we have fixed the AST.
	Src []byte

	cursor     inspector.Cursor // cursor of *ast.File, sans sibling files
	cursorOnce sync.Once

	// fixedSrc and fixedAST report on "fixing" that occurred during parsing of
	// this file.
	//
	// fixedSrc means Src holds file content that was modified to improve parsing.
	// fixedAST means File was modified after parsing, so AST positions may not
	// reflect the content of Src.
	//
	// TODO(rfindley): there are many places where we haphazardly use the Src or
	// positions without checking these fields. Audit these places and guard
	// accordingly. After doing so, we may find that we don't need to
	// differentiate fixedSrc and fixedAST.
	fixedSrc bool
	fixedAST bool
	Mapper   *protocol.Mapper // may map fixed Src, not file content
	ParseErr scanner.ErrorList

	// resolveOnce guards the lazy ast.Object resolution. See [File.Resolve].
	resolveOnce sync.Once
}

func (pgf *File) String() string { return string(pgf.URI) }

// Cursor returns a cursor for pgf.File, for fast and convenient navigation.
func (pgf *File) Cursor() inspector.Cursor {
	pgf.cursorOnce.Do(func() {
		inspect := inspector.New([]*ast.File{pgf.File})
		pgf.cursor, _ = inspect.Root().FirstChild()
		_ = pgf.cursor.Node().(*ast.File)
	})
	return pgf.cursor
}

// Fixed reports whether p was "Fixed", meaning that its source or positions
// may not correlate with the original file.
func (pgf *File) Fixed() bool {
	return pgf.fixedSrc || pgf.fixedAST
}

// -- go/token domain convenience helpers --

// PositionPos returns the token.Pos of protocol position p within the file.
func (pgf *File) PositionPos(p protocol.Position) (token.Pos, error) {
	offset, err := pgf.Mapper.PositionOffset(p)
	if err != nil {
		return token.NoPos, err
	}
	return safetoken.Pos(pgf.Tok, offset)
}

// PosPosition returns a protocol Position for the token.Pos in this file.
func (pgf *File) PosPosition(pos token.Pos) (protocol.Position, error) {
	return pgf.Mapper.PosPosition(pgf.Tok, pos)
}

// PosRange returns a protocol Range for the token.Pos interval in this file.
func (pgf *File) PosRange(start, end token.Pos) (protocol.Range, error) {
	return pgf.Mapper.PosRange(pgf.Tok, start, end)
}

// PosLocation returns a protocol Location for the token.Pos interval in this file.
func (pgf *File) PosLocation(start, end token.Pos) (protocol.Location, error) {
	return pgf.Mapper.PosLocation(pgf.Tok, start, end)
}

// PosText returns the source text for the token.Pos interval in this file.
func (pgf *File) PosText(start, end token.Pos) ([]byte, error) {
	return pgf.Mapper.PosText(pgf.Tok, start, end)
}

// NodeRange returns a protocol Range for the ast.Node interval in this file.
func (pgf *File) NodeRange(node ast.Node) (protocol.Range, error) {
	return pgf.Mapper.NodeRange(pgf.Tok, node)
}

// NodeOffsets returns offsets for the ast.Node.
func (pgf *File) NodeOffsets(node ast.Node) (start int, end int, _ error) {
	return safetoken.Offsets(pgf.Tok, node.Pos(), node.End())
}

// NodeLocation returns a protocol Location for the ast.Node interval in this file.
func (pgf *File) NodeLocation(node ast.Node) (protocol.Location, error) {
	return pgf.Mapper.PosLocation(pgf.Tok, node.Pos(), node.End())
}

// NodeText returns the source text for the ast.Node interval in this file.
func (pgf *File) NodeText(node ast.Node) ([]byte, error) {
	return pgf.Mapper.NodeText(pgf.Tok, node)
}

// RangePos parses a protocol Range back into the go/token domain.
func (pgf *File) RangePos(r protocol.Range) (token.Pos, token.Pos, error) {
	start, end, err := pgf.Mapper.RangeOffsets(r)
	if err != nil {
		return token.NoPos, token.NoPos, err
	}
	return pgf.Tok.Pos(start), pgf.Tok.Pos(end), nil
}

// CheckNode asserts that the Node's positions are valid w.r.t. pgf.Tok.
func (pgf *File) CheckNode(node ast.Node) {
	// Avoid safetoken.Offsets, and put each assertion on its own source line.
	pgf.CheckPos(node.Pos())
	pgf.CheckPos(node.End())
}

// CheckPos asserts that the position is valid w.r.t. pgf.Tok.
func (pgf *File) CheckPos(pos token.Pos) {
	if !pos.IsValid() {
		bug.Report("invalid token.Pos")
	} else if _, err := safetoken.Offset(pgf.Tok, pos); err != nil {
		bug.Report("token.Pos out of range")
	}
}

// Resolve lazily resolves ast.Ident.Objects in the enclosed syntax tree.
//
// Resolve must be called before accessing any of:
//   - pgf.File.Scope
//   - pgf.File.Unresolved
//   - Ident.Obj, for any Ident in pgf.File
func (pgf *File) Resolve() {
	pgf.resolveOnce.Do(func() {
		if pgf.File.Scope != nil {
			return // already resolved by parsing without SkipObjectResolution.
		}
		defer func() {
			// (panic handler duplicated from go/parser)
			if e := recover(); e != nil {
				// A bailout indicates the resolution stack has exceeded max depth.
				if _, ok := e.(bailout); !ok {
					panic(e)
				}
			}
		}()
		declErr := func(token.Pos, string) {}
		resolveFile(pgf.File, pgf.Tok, declErr)
	})
}

// Indentation returns the string of spaces representing the indentation
// of the line containing the specified position.
// This can be used to ensure that inserted code maintains consistent indentation
// and column alignment.
func (pgf *File) Indentation(pos token.Pos) (string, error) {
	line := safetoken.Line(pgf.Tok, pos)
	start, end, err := safetoken.Offsets(pgf.Tok, pgf.Tok.LineStart(line), pos)
	if err != nil {
		return "", err
	}

	s := string(pgf.Src[start:end])
	for i, r := range s {
		if !unicode.IsSpace(r) {
			return s[:i], nil // prefix of spaces
		}
	}
	return s, nil
}


================================================
FILE: gopls/internal/cache/parsego/parse.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run resolver_gen.go

// The parsego package defines the [File] type, a wrapper around a go/ast.File
// that is useful for answering LSP queries. Notably, it bundles the
// *token.File and *protocol.Mapper necessary for token.Pos locations to and
// from UTF-16 LSP positions.
//
// Run `go generate` to update resolver.go from GOROOT.
package parsego

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/parser"
	"go/scanner"
	"go/token"
	"reflect"
	"slices"

	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
)

// Common parse modes; these should be reused wherever possible to increase
// cache hits.
const (
	// Header specifies that the main package declaration and imports are needed.
	// This is the mode used when attempting to examine the package graph structure.
	Header = parser.AllErrors | parser.ParseComments | parser.ImportsOnly | parser.SkipObjectResolution

	// Full specifies the full AST is needed.
	// This is used for files of direct interest where the entire contents must
	// be considered.
	Full = parser.AllErrors | parser.ParseComments | parser.SkipObjectResolution
)

// Parse parses a buffer of Go source, repairing the tree if necessary.
//
// The provided ctx is used only for logging.
func Parse(ctx context.Context, fset *token.FileSet, uri protocol.DocumentURI, src []byte, mode parser.Mode, purgeFuncBodies bool) (res *File, fixes []FixType) {
	if purgeFuncBodies {
		src = astutil.PurgeFuncBodies(src)
	}
	ctx, done := event.Start(ctx, "cache.ParseGoSrc", label.File.Of(uri.Path()))
	defer done()

	file, err := parser.ParseFile(fset, uri.Path(), src, mode)
	var parseErr scanner.ErrorList
	if err != nil {
		// We passed a byte slice, so the only possible error is a parse error.
		parseErr = err.(scanner.ErrorList)
	}
	// Inv: file != nil.

	tokenFile := func(file *ast.File) *token.File {
		return fset.File(file.FileStart)
	}

	tok := tokenFile(file)

	fixedSrc := false
	fixedAST := false
	// If there were parse errors, attempt to fix them up.
	if parseErr != nil {
		// Fix any badly parsed parts of the AST.
		astFixes := fixAST(file, tok, src)
		fixedAST = len(astFixes) > 0
		if fixedAST {
			fixes = append(fixes, astFixes...)
		}

		for i := range 10 {
			// Fix certain syntax errors that render the file unparsable.
			newSrc, srcFix := fixSrc(file, tok, src)
			if newSrc == nil {
				break
			}

			// If we thought there was something to fix 10 times in a row,
			// it is likely we got stuck in a loop somehow. Log out a diff
			// of the last changes we made to aid in debugging.
			if i == 9 {
				unified := diff.Unified("before", "after", string(src), string(newSrc))
				event.Log(ctx, fmt.Sprintf("fixSrc loop - last diff:\n%v", unified), label.File.Of(tok.Name()))
			}

			newFile, newErr := parser.ParseFile(fset, uri.Path(), newSrc, mode)
			assert(newFile != nil, "ParseFile returned nil") // I/O error can't happen

			// Maintain the original parseError so we don't try formatting the
			// doctored file.
			file = newFile
			src = newSrc
			tok = tokenFile(file)

			// Only now that we accept the fix do we record the src fix from above.
			fixes = append(fixes, srcFix)
			fixedSrc = true

			if newErr == nil {
				break // nothing to fix
			}

			// Note that fixedAST is reset after we fix src.
			astFixes = fixAST(file, tok, src)
			fixedAST = len(astFixes) > 0
			if fixedAST {
				fixes = append(fixes, astFixes...)
			}
		}
	}
	assert(file != nil, "nil *ast.File")

	return &File{
		URI:      uri,
		Mode:     mode,
		Src:      src,
		fixedSrc: fixedSrc,
		fixedAST: fixedAST,
		File:     file,
		Tok:      tok,
		Mapper:   protocol.NewMapper(uri, src),
		ParseErr: parseErr,
	}, fixes
}

// fixAST inspects the AST and potentially modifies any *ast.BadStmts so that it can be
// type-checked more effectively.
//
// If fixAST returns true, the resulting AST is considered "fixed", meaning
// positions have been mangled, and type checker errors may not make sense.
func fixAST(n ast.Node, tok *token.File, src []byte) (fixes []FixType) {
	var err error
	ast.PreorderStack(n, nil, func(n ast.Node, stack []ast.Node) bool {
		var parent ast.Node
		if len(stack) > 0 {
			parent = stack[len(stack)-1]
		}

		switch n := n.(type) {
		case *ast.BadStmt:
			if fixDeferOrGoStmt(n, parent, tok, src) {
				fixes = append(fixes, FixedDeferOrGo)
				// Recursively fix in our fixed node.
				moreFixes := fixAST(parent, tok, src)
				fixes = append(fixes, moreFixes...)
			} else {
				err = fmt.Errorf("unable to parse defer or go from *ast.BadStmt: %v", err)
			}
			return false
		case *ast.BadExpr:
			if fixArrayType(n, parent, tok, src) {
				fixes = append(fixes, FixedArrayType)
				// Recursively fix in our fixed node.
				moreFixes := fixAST(parent, tok, src)
				fixes = append(fixes, moreFixes...)
				return false
			}

			// Fix cases where parser interprets if/for/switch "init"
			// statement as "cond" expression, e.g.:
			//
			//   // "i := foo" is init statement, not condition.
			//   for i := foo
			//
			if fixInitStmt(n, parent, tok, src) {
				fixes = append(fixes, FixedInit)
			}
			return false
		case *ast.SelectorExpr:
			// Fix cases where a keyword prefix results in a phantom "_" selector, e.g.:
			//
			//   foo.var<> // want to complete to "foo.variance"
			//
			if fixPhantomSelector(n, tok, src) {
				fixes = append(fixes, FixedPhantomSelector)
			}
			return true

		case *ast.BlockStmt:
			switch parent.(type) {
			case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
				// Adjust closing curly brace of empty switch/select
				// statements so we can complete inside them.
				if fixEmptySwitch(n, tok, src) {
					fixes = append(fixes, FixedEmptySwitch)
				}
			}

			return true
		default:
			return true
		}
	})
	return fixes
}

// TODO(rfindley): revert this instrumentation once we're certain the crash in
// #59097 is fixed.
type FixType int

const (
	noFix FixType = iota
	FixedCurlies
	FixedDanglingSelector
	FixedDeferOrGo
	FixedArrayType
	FixedInit
	FixedPhantomSelector
	FixedEmptySwitch
)

// fixSrc attempts to modify the file's source code to fix certain
// syntax errors that leave the rest of the file unparsed.
//
// fixSrc returns a non-nil result if and only if a fix was applied.
func fixSrc(f *ast.File, tf *token.File, src []byte) (newSrc []byte, fix FixType) {
	ast.PreorderStack(f, nil, func(n ast.Node, stack []ast.Node) bool {
		if newSrc != nil {
			return false
		}

		switch n := n.(type) {
		case *ast.BlockStmt:
			parent := stack[len(stack)-1]
			newSrc = fixMissingCurlies(f, n, parent, tf, src)
			if newSrc != nil {
				fix = FixedCurlies
			}
		case *ast.SelectorExpr:
			newSrc = fixDanglingSelector(n, tf, src)
			if newSrc != nil {
				fix = FixedDanglingSelector
			}
		}

		return newSrc == nil
	})

	return newSrc, fix
}

// fixMissingCurlies adds in curly braces for block statements that
// are missing curly braces. For example:
//
//	if foo
//
// becomes
//
//	if foo {}
func fixMissingCurlies(f *ast.File, b *ast.BlockStmt, parent ast.Node, tok *token.File, src []byte) []byte {
	// If the "{" is already in the source code, there isn't anything to
	// fix since we aren't missing curlies.
	if b.Lbrace.IsValid() {
		braceOffset, err := safetoken.Offset(tok, b.Lbrace)
		if err != nil {
			return nil
		}
		if braceOffset < len(src) && src[braceOffset] == '{' {
			return nil
		}
	}

	parentLine := safetoken.Line(tok, parent.Pos())

	if parentLine >= tok.LineCount() {
		// If we are the last line in the file, no need to fix anything.
		return nil
	}

	// Insert curlies at the end of parent's starting line. The parent
	// is the statement that contains the block, e.g. *ast.IfStmt. The
	// block's Pos()/End() can't be relied upon because they are based
	// on the (missing) curly braces. We assume the statement is a
	// single line for now and try sticking the curly braces at the end.
	insertPos := tok.LineStart(parentLine+1) - 1

	// Scootch position backwards until it's not in a comment. For example:
	//
	// if foo<> // some amazing comment |
	// someOtherCode()
	//
	// insertPos will be located at "|", so we back it out of the comment.
	didSomething := true
	for didSomething {
		didSomething = false
		for _, c := range f.Comments {
			if c.Pos() < insertPos && insertPos <= c.End() {
				insertPos = c.Pos()
				didSomething = true
			}
		}
	}

	// Bail out if line doesn't end in an ident or ".". This is to avoid
	// cases like below where we end up making things worse by adding
	// curlies:
	//
	//   if foo &&
	//     bar<>
	switch precedingToken(insertPos, tok, src) {
	case token.IDENT, token.PERIOD:
		// ok
	default:
		return nil
	}

	var buf bytes.Buffer
	buf.Grow(len(src) + 3)
	offset, err := safetoken.Offset(tok, insertPos)
	if err != nil {
		return nil
	}
	buf.Write(src[:offset])

	// Detect if we need to insert a semicolon to fix "for" loop situations like:
	//
	//   for i := foo(); foo<>
	//
	// Just adding curlies is not sufficient to make things parse well.
	if fs, ok := parent.(*ast.ForStmt); ok {
		if _, ok := fs.Cond.(*ast.BadExpr); !ok {
			if xs, ok := fs.Post.(*ast.ExprStmt); ok {
				if _, ok := xs.X.(*ast.BadExpr); ok {
					buf.WriteByte(';')
				}
			}
		}
	}

	// Insert "{}" at insertPos.
	buf.WriteByte('{')
	buf.WriteByte('}')
	buf.Write(src[offset:])
	return buf.Bytes()
}

// fixEmptySwitch moves empty switch/select statements' closing curly
// brace down one line. This allows us to properly detect incomplete
// "case" and "default" keywords as inside the switch statement. For
// example:
//
//	switch {
//	def<>
//	}
//
// gets parsed like:
//
//	switch {
//	}
//
// Later we manually pull out the "def" token, but we need to detect
// that our "<>" position is inside the switch block. To do that we
// move the curly brace so it looks like:
//
//	switch {
//
//	}
//
// The resulting bool reports whether any fixing occurred.
func fixEmptySwitch(body *ast.BlockStmt, tok *token.File, src []byte) bool {
	// We only care about empty switch statements.
	if len(body.List) > 0 || !body.Rbrace.IsValid() {
		return false
	}

	// If the right brace is actually in the source code at the
	// specified position, don't mess with it.
	braceOffset, err := safetoken.Offset(tok, body.Rbrace)
	if err != nil {
		return false
	}
	if braceOffset < len(src) && src[braceOffset] == '}' {
		return false
	}

	braceLine := safetoken.Line(tok, body.Rbrace)
	if braceLine >= tok.LineCount() {
		// If we are the last line in the file, no need to fix anything.
		return false
	}

	// Move the right brace down one line.
	body.Rbrace = tok.LineStart(braceLine + 1)
	return true
}

// fixDanglingSelector inserts a real "_" selector expression in place
// of a phantom parser-inserted "_" selector so that the parser will
// not consume the following non-identifier token.
// For example:
//
//	func _() {
//		x.<>
//	}
//
// var x struct { i int }
//
// To fix completion at "<>", we insert a real "_" after the "." so the
// following declaration of "x" can be parsed and type checked
// normally.
func fixDanglingSelector(s *ast.SelectorExpr, tf *token.File, src []byte) []byte {
	if !isPhantomUnderscore(s.Sel, tf, src) {
		return nil
	}

	if !s.X.End().IsValid() {
		return nil
	}

	insertOffset, err := safetoken.Offset(tf, s.X.End())
	if err != nil {
		return nil
	}
	// Insert directly after the selector's ".".
	insertOffset++
	if src[insertOffset-1] != '.' {
		return nil
	}

	return slices.Concat(src[:insertOffset], []byte("_"), src[insertOffset:])
}

// fixPhantomSelector tries to fix selector expressions whose Sel is a
// phantom (parser-invented) "_". If the text after the '.' is a
// keyword, it updates Sel to a fake ast.Ident of that name. For
// example:
//
// foo.var
//
// yields a "_" selector instead of "var" since "var" is a keyword.
//
// TODO(rfindley): should this constitute an ast 'fix'?
//
// The resulting bool reports whether any fixing occurred.
func fixPhantomSelector(sel *ast.SelectorExpr, tf *token.File, src []byte) bool {
	if !isPhantomUnderscore(sel.Sel, tf, src) {
		return false
	}

	// Only consider selectors directly abutting the selector ".". This
	// avoids false positives in cases like:
	//
	//   foo. // don't think "var" is our selector
	//   var bar = 123
	//
	if sel.Sel.Pos() != sel.X.End()+1 {
		return false
	}

	maybeKeyword := readKeyword(sel.Sel.Pos(), tf, src)
	if maybeKeyword == "" {
		return false
	}

	return replaceNode(sel, sel.Sel, &ast.Ident{
		Name:    maybeKeyword,
		NamePos: sel.Sel.Pos(),
	})
}

// isPhantomUnderscore reports whether the given ident from a
// SelectorExpr.Sel was invented by the parser and is not present in
// source text. The parser creates a blank "_" identifier when the
// syntax (e.g. a selector) demands one but none is present. The fixer
// also inserts them.
func isPhantomUnderscore(id *ast.Ident, tok *token.File, src []byte) bool {
	switch id.Name {
	case "_": // go1.24 parser
		offset, err := safetoken.Offset(tok, id.Pos())
		return err == nil && offset < len(src) && src[offset] != '_'
	}
	return false // real
}

// fixInitStmt fixes cases where the parser misinterprets an
// if/for/switch "init" statement as the "cond" conditional. In cases
// like "if i := 0" the user hasn't typed the semicolon yet so the
// parser is looking for the conditional expression. However, "i := 0"
// are not valid expressions, so we get a BadExpr.
//
// The resulting bool reports whether any fixing occurred.
func fixInitStmt(bad *ast.BadExpr, parent ast.Node, tok *token.File, src []byte) bool {
	if !bad.Pos().IsValid() || !bad.End().IsValid() {
		return false
	}

	// Try to extract a statement from the BadExpr.
	start, end, err := safetoken.Offsets(tok, bad.Pos(), bad.End())
	if err != nil {
		return false
	}
	assert(end <= len(src), "offset overflow") // golang/go#72026
	stmtBytes := src[start:end]
	stmt, err := parseStmt(tok, bad.Pos(), stmtBytes)
	if err != nil {
		return false
	}

	// If the parent statement doesn't already have an "init" statement,
	// move the extracted statement into the "init" field and insert a
	// dummy expression into the required "cond" field.
	switch p := parent.(type) {
	case *ast.IfStmt:
		if p.Init != nil {
			return false
		}
		p.Init = stmt
		p.Cond = &ast.Ident{
			Name:    "_",
			NamePos: stmt.End(),
		}
		return true
	case *ast.ForStmt:
		if p.Init != nil {
			return false
		}
		p.Init = stmt
		p.Cond = &ast.Ident{
			Name:    "_",
			NamePos: stmt.End(),
		}
		return true
	case *ast.SwitchStmt:
		if p.Init != nil {
			return false
		}
		p.Init = stmt
		p.Tag = nil
		return true
	}
	return false
}

// readKeyword reads the keyword starting at pos, if any.
func readKeyword(pos token.Pos, tok *token.File, src []byte) string {
	var kwBytes []byte
	offset, err := safetoken.Offset(tok, pos)
	if err != nil {
		return ""
	}
	for i := offset; i < len(src); i++ {
		// Use a simplified identifier check since keywords are always lowercase ASCII.
		if src[i] < 'a' || src[i] > 'z' {
			break
		}
		kwBytes = append(kwBytes, src[i])

		// Stop search at arbitrarily chosen too-long-for-a-keyword length.
		if len(kwBytes) > 15 {
			return ""
		}
	}

	if kw := string(kwBytes); token.Lookup(kw).IsKeyword() {
		return kw
	}

	return ""
}

// fixArrayType tries to parse an *ast.BadExpr into an *ast.ArrayType.
// go/parser often turns lone array types like "[]int" into BadExprs
// if it isn't expecting a type.
func fixArrayType(bad *ast.BadExpr, parent ast.Node, tok *token.File, src []byte) bool {
	// Our expected input is a bad expression that looks like "[]someExpr".

	from, to := bad.Pos(), bad.End()
	fromOffset, toOffset, err := safetoken.Offsets(tok, from, to)
	if err != nil {
		return false
	}

	exprBytes := bytes.TrimSpace(slices.Clone(src[fromOffset:toOffset]))

	// If our expression ends in "]" (e.g. "[]"), add a phantom selector
	// so we can complete directly after the "[]".
	if bytes.HasSuffix(exprBytes, []byte("]")) {
		exprBytes = append(exprBytes, '_')
	}

	// Add "{}" to turn our ArrayType into a CompositeLit. This is to
	// handle the case of "[...]int" where we must make it a composite
	// literal to be parseable.
	exprBytes = append(exprBytes, '{', '}')

	expr, err := parseExpr(tok, from, exprBytes)
	if err != nil {
		return false
	}

	cl, _ := expr.(*ast.CompositeLit)
	if cl == nil {
		return false
	}

	at, _ := cl.Type.(*ast.ArrayType)
	if at == nil {
		return false
	}

	return replaceNode(parent, bad, at)
}

// precedingToken scans src to find the token preceding pos.
func precedingToken(pos token.Pos, tok *token.File, src []byte) token.Token {
	s := &scanner.Scanner{}
	s.Init(tok, src, nil, 0)

	var lastTok token.Token
	for {
		p, t, _ := s.Scan()
		if t == token.EOF || p >= pos {
			break
		}

		lastTok = t
	}
	return lastTok
}

// fixDeferOrGoStmt tries to parse an *ast.BadStmt into a defer or a go statement.
//
// go/parser packages a statement of the form "defer x." as an *ast.BadStmt because
// it does not include a call expression. This means that go/types skips type-checking
// this statement entirely, and we can't use the type information when completing.
// Here, we try to generate a fake *ast.DeferStmt or *ast.GoStmt to put into the AST,
// instead of the *ast.BadStmt.
func fixDeferOrGoStmt(bad *ast.BadStmt, parent ast.Node, tok *token.File, src []byte) bool {
	// Check if we have a bad statement containing either a "go" or "defer".
	s := &scanner.Scanner{}
	s.Init(tok, src, nil, 0)

	var (
		pos token.Pos
		tkn token.Token
	)
	for {
		if tkn == token.EOF {
			return false
		}
		if pos >= bad.From {
			break
		}
		pos, tkn, _ = s.Scan()
	}

	var stmt ast.Stmt
	switch tkn {
	case token.DEFER:
		stmt = &ast.DeferStmt{
			Defer: pos,
		}
	case token.GO:
		stmt = &ast.GoStmt{
			Go: pos,
		}
	default:
		return false
	}

	var (
		from, to, last   token.Pos
		lastToken        token.Token
		braceDepth       int
		phantomSelectors []token.Pos
	)
FindTo:
	for {
		to, tkn, _ = s.Scan()

		if from == token.NoPos {
			from = to
		}

		switch tkn {
		case token.EOF:
			break FindTo
		case token.SEMICOLON:
			// If we aren't in nested braces, end of statement means
			// end of expression.
			if braceDepth == 0 {
				break FindTo
			}
		case token.LBRACE:
			braceDepth++
		}

		// This handles the common dangling selector case. For example in
		//
		// defer fmt.
		// y := 1
		//
		// we notice the dangling period and end our expression.
		//
		// If the previous token was a "." and we are looking at a "}",
		// the period is likely a dangling selector and needs a phantom
		// "_". Likewise if the current token is on a different line than
		// the period, the period is likely a dangling selector.
		if lastToken == token.PERIOD && (tkn == token.RBRACE || safetoken.Line(tok, to) > safetoken.Line(tok, last)) {
			// Insert phantom "_" selector after the dangling ".".
			phantomSelectors = append(phantomSelectors, last+1)
			// If we aren't in a block then end the expression after the ".".
			if braceDepth == 0 {
				to = last + 1
				break
			}
		}

		lastToken = tkn
		last = to

		switch tkn {
		case token.RBRACE:
			braceDepth--
			if braceDepth <= 0 {
				if braceDepth == 0 {
					// +1 to include the "}" itself.
					to += 1
				}
				break FindTo
			}
		}
	}

	fromOffset, toOffset, err := safetoken.Offsets(tok, from, to)
	if err != nil {
		return false
	}
	if !from.IsValid() || fromOffset >= len(src) {
		return false
	}
	if !to.IsValid() || toOffset >= len(src) {
		return false
	}

	// Insert any phantom selectors needed to prevent dangling "." from messing
	// up the AST.
	exprBytes := make([]byte, 0, int(to-from)+len(phantomSelectors))
	for i, b := range src[fromOffset:toOffset] {
		if len(phantomSelectors) > 0 && from+token.Pos(i) == phantomSelectors[0] {
			exprBytes = append(exprBytes, '_')
			phantomSelectors = phantomSelectors[1:]
		}
		exprBytes = append(exprBytes, b)
	}

	if len(phantomSelectors) > 0 {
		exprBytes = append(exprBytes, '_')
	}

	expr, err := parseExpr(tok, from, exprBytes)
	if err != nil {
		return false
	}

	// Package the expression into a fake *ast.CallExpr and re-insert
	// into the function.
	call := &ast.CallExpr{
		Fun:    expr,
		Lparen: to,
		Rparen: to,
	}

	switch stmt := stmt.(type) {
	case *ast.DeferStmt:
		stmt.Call = call
	case *ast.GoStmt:
		stmt.Call = call
	}

	return replaceNode(parent, bad, stmt)
}

// parseStmt parses the statement in src and updates its position to
// start at pos.
//
// tok is the original file containing pos. Used to ensure that all adjusted
// positions are valid.
func parseStmt(tok *token.File, pos token.Pos, src []byte) (ast.Stmt, error) {
	// Wrap our expression to make it a valid Go file we can pass to ParseFile.
	fileSrc := slices.Concat([]byte("package fake;func _(){"), src, []byte("}"))

	// Use ParseFile instead of ParseExpr because ParseFile has
	// best-effort behavior, whereas ParseExpr fails hard on any error.
	fakeFile, err := parser.ParseFile(token.NewFileSet(), "", fileSrc, parser.SkipObjectResolution)
	if fakeFile == nil {
		return nil, fmt.Errorf("error reading fake file source: %v", err)
	}

	// Extract our expression node from inside the fake file.
	if len(fakeFile.Decls) == 0 {
		return nil, fmt.Errorf("error parsing fake file: %v", err)
	}

	fakeDecl, _ := fakeFile.Decls[0].(*ast.FuncDecl)
	if fakeDecl == nil || len(fakeDecl.Body.List) == 0 {
		return nil, fmt.Errorf("no statement in %s: %v", src, err)
	}

	stmt := fakeDecl.Body.List[0]

	// parser.ParseFile returns undefined positions.
	// Adjust them for the current file.
	offsetPositions(tok, stmt, pos-1-(stmt.Pos()-1))

	return stmt, nil
}

// parseExpr parses the expression in src and updates its position to
// start at pos.
func parseExpr(tok *token.File, pos token.Pos, src []byte) (ast.Expr, error) {
	stmt, err := parseStmt(tok, pos, src)
	if err != nil {
		return nil, err
	}

	exprStmt, ok := stmt.(*ast.ExprStmt)
	if !ok {
		return nil, fmt.Errorf("no expr in %s: %v", src, err)
	}

	return exprStmt.X, nil
}

var tokenPosType = reflect.TypeFor[token.Pos]()

// offsetPositions applies an offset to the positions in an ast.Node.
func offsetPositions(tok *token.File, n ast.Node, offset token.Pos) {
	fileBase := token.Pos(tok.Base())
	fileEnd := fileBase + token.Pos(tok.Size())
	ast.Inspect(n, func(n ast.Node) bool {
		if n == nil {
			return false
		}

		v := reflect.ValueOf(n).Elem()

		switch v.Kind() {
		case reflect.Struct:
			for i := 0; i < v.NumField(); i++ {
				f := v.Field(i)
				if f.Type() != tokenPosType {
					continue
				}

				if !f.CanSet() {
					continue
				}

				pos := token.Pos(f.Int())

				// Don't offset invalid positions: they should stay invalid.
				if !pos.IsValid() {
					continue
				}

				// Clamp value to valid range; see #64335.
				//
				// TODO(golang/go#64335): this is a hack, because our fixes should not
				// produce positions that overflow (but they do; see golang/go#64488,
				// #73438, #66790, #66683, #67704).
				pos = min(max(pos+offset, fileBase), fileEnd)

				f.SetInt(int64(pos))
			}
		}

		return true
	})
}

// replaceNode updates parent's child oldChild to be newChild. It
// returns whether it replaced successfully.
func replaceNode(parent, oldChild, newChild ast.Node) bool {
	if parent == nil || oldChild == nil || newChild == nil {
		return false
	}

	parentVal := reflect.ValueOf(parent).Elem()
	if parentVal.Kind() != reflect.Struct {
		return false
	}

	newChildVal := reflect.ValueOf(newChild)

	tryReplace := func(v reflect.Value) bool {
		if !v.CanSet() || !v.CanInterface() {
			return false
		}

		// If the existing value is oldChild, we found our child. Make
		// sure our newChild is assignable and then make the swap.
		if v.Interface() == oldChild && newChildVal.Type().AssignableTo(v.Type()) {
			v.Set(newChildVal)
			return true
		}

		return false
	}

	// Loop over parent's struct fields.
	for i := 0; i < parentVal.NumField(); i++ {
		f := parentVal.Field(i)

		switch f.Kind() {
		// Check interface and pointer fields.
		case reflect.Interface, reflect.Pointer:
			if tryReplace(f) {
				return true
			}

		// Search through any slice fields.
		case reflect.Slice:
			for i := 0; i < f.Len(); i++ {
				if tryReplace(f.Index(i)) {
					return true
				}
			}
		}
	}

	return false
}


================================================
FILE: gopls/internal/cache/parsego/parse_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package parsego_test

import (
	"context"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"reflect"
	"slices"
	"testing"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/astutil"
)

// TODO(golang/go#64335): we should have many more tests for fixed syntax.

func TestFixPosition_Issue64488(t *testing.T) {
	// This test reproduces the conditions of golang/go#64488, where a type error
	// on fixed syntax overflows the token.File.
	const src = `
package foo

func _() {
	type myThing struct{}
	var foo []myThing
	for ${1:}, ${2:} := range foo {
	$0
}
}
`

	pgf, _ := parsego.Parse(context.Background(), token.NewFileSet(), "file://foo.go", []byte(src), parsego.Full, false)
	fset := tokeninternal.FileSetFor(pgf.Tok)
	ast.Inspect(pgf.File, func(n ast.Node) bool {
		if n != nil {
			posn := safetoken.StartPosition(fset, n.Pos())
			if !posn.IsValid() {
				t.Fatalf("invalid position for %T (%v): %v not in [%d, %d]", n, n, n.Pos(), pgf.Tok.Base(), pgf.Tok.Base()+pgf.Tok.Size())
			}
		}
		return true
	})
}

func TestFixGoAndDefer(t *testing.T) {
	var testCases = []struct {
		source  string
		fixes   []parsego.FixType
		wantFix string
	}{
		{source: "", fixes: nil}, // keyword alone
		{source: "a.b(", fixes: nil},
		{source: "a.b()", fixes: nil},
		{source: "func {", fixes: nil},
		{
			source:  "f",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "f()",
		},
		{
			source:  "func",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "(func())()",
		},
		{
			source:  "func {}",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "(func())()",
		},
		{
			source:  "func {}(",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "(func())()",
		},
		{
			source:  "func {}()",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "(func())()",
		},
		{
			source:  "a.",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo, parsego.FixedDanglingSelector, parsego.FixedDeferOrGo},
			wantFix: "a._()",
		},
		{
			source:  "a.b",
			fixes:   []parsego.FixType{parsego.FixedDeferOrGo},
			wantFix: "a.b()",
		},
	}

	for _, keyword := range []string{"go", "defer"} {
		for _, tc := range testCases {
			source := fmt.Sprintf("%s %s", keyword, tc.source)
			t.Run(source, func(t *testing.T) {
				src := filesrc(source)
				pgf, fixes := parsego.Parse(context.Background(), token.NewFileSet(), "file://foo.go", src, parsego.Full, false)
				if !slices.Equal(fixes, tc.fixes) {
					t.Fatalf("got %v want %v", fixes, tc.fixes)
				}
				if tc.fixes == nil {
					return
				}

				fset := tokeninternal.FileSetFor(pgf.Tok)
				inspect(t, pgf, func(stmt ast.Stmt) {
					var call *ast.CallExpr
					switch stmt := stmt.(type) {
					case *ast.DeferStmt:
						call = stmt.Call
					case *ast.GoStmt:
						call = stmt.Call
					default:
						return
					}

					if got := astutil.Format(fset, call); got != tc.wantFix {
						t.Fatalf("got %v want %v", got, tc.wantFix)
					}
				})
			})
		}
	}
}

// TestFixInit tests the init stmt after if/for/switch which is put under cond after parsing
// will be fixed and moved to Init.
func TestFixInit(t *testing.T) {
	var testCases = []struct {
		name        string
		source      string
		fixes       []parsego.FixType
		wantInitFix string
	}{
		{
			name:        "simple define",
			source:      "i := 0",
			fixes:       []parsego.FixType{parsego.FixedInit},
			wantInitFix: "i := 0",
		},
		{
			name:        "simple assign",
			source:      "i = 0",
			fixes:       []parsego.FixType{parsego.FixedInit},
			wantInitFix: "i = 0",
		},
		{
			name:        "define with function call",
			source:      "i := f()",
			fixes:       []parsego.FixType{parsego.FixedInit},
			wantInitFix: "i := f()",
		},
		{
			name:        "assign with function call",
			source:      "i = f()",
			fixes:       []parsego.FixType{parsego.FixedInit},
			wantInitFix: "i = f()",
		},
		{
			name:        "assign with receiving chan",
			source:      "i = <-ch",
			fixes:       []parsego.FixType{parsego.FixedInit},
			wantInitFix: "i = <-ch",
		},

		// fixInitStmt won't fix the following cases.
		{
			name:   "call in if",
			source: `fmt.Println("helloworld")`,
			fixes:  nil,
		},
		{
			name:   "receive chan",
			source: `<- ch`,
			fixes:  nil,
		},
	}

	// currently, switch will leave its Tag empty after fix because it allows empty,
	// and if and for will leave an underscore in Cond.
	getWantCond := func(keyword string) string {
		if keyword == "switch" {
			return ""
		}
		return "_"
	}

	for _, keyword := range []string{"if", "for", "switch"} {
		for _, tc := range testCases {
			caseName := fmt.Sprintf("%s %s", keyword, tc.name)
			t.Run(caseName, func(t *testing.T) {
				// the init stmt is treated as a cond.
				src := filesrc(fmt.Sprintf("%s %s {}", keyword, tc.source))
				pgf, fixes := parsego.Parse(context.Background(), token.NewFileSet(), "file://foo.go", src, parsego.Full, false)
				if !slices.Equal(fixes, tc.fixes) {
					t.Fatalf("TestFixArrayType(): got %v want %v", fixes, tc.fixes)
				}
				if tc.fixes == nil {
					return
				}

				// ensure the init stmt is parsed to a BadExpr.
				ensureSource(t, src, func(bad *ast.BadExpr) {})

				info := func(n ast.Node, wantStmt string) (init ast.Stmt, cond ast.Expr, has bool) {
					switch wantStmt {
					case "if":
						if e, ok := n.(*ast.IfStmt); ok {
							return e.Init, e.Cond, true
						}
					case "switch":
						if e, ok := n.(*ast.SwitchStmt); ok {
							return e.Init, e.Tag, true
						}
					case "for":
						if e, ok := n.(*ast.ForStmt); ok {
							return e.Init, e.Cond, true
						}
					}
					return nil, nil, false
				}
				fset := tokeninternal.FileSetFor(pgf.Tok)
				inspect(t, pgf, func(n ast.Stmt) {
					if init, cond, ok := info(n, keyword); ok {
						if got := astutil.Format(fset, init); got != tc.wantInitFix {
							t.Fatalf("%s: Init got %v want %v", tc.source, got, tc.wantInitFix)
						}

						wantCond := getWantCond(keyword)
						if got := astutil.Format(fset, cond); got != wantCond {
							t.Fatalf("%s: Cond got %v want %v", tc.source, got, wantCond)
						}
					}
				})
			})
		}
	}
}

func TestFixPhantomSelector(t *testing.T) {
	wantFixes := []parsego.FixType{parsego.FixedPhantomSelector}
	var testCases = []struct {
		source string
		fixes  []parsego.FixType
	}{
		{source: "a.break", fixes: wantFixes},
		{source: "_.break", fixes: wantFixes},
		{source: "a.case", fixes: wantFixes},
		{source: "a.chan", fixes: wantFixes},
		{source: "a.const", fixes: wantFixes},
		{source: "a.continue", fixes: wantFixes},
		{source: "a.default", fixes: wantFixes},
		{source: "a.defer", fixes: wantFixes},
		{source: "a.else", fixes: wantFixes},
		{source: "a.fallthrough", fixes: wantFixes},
		{source: "a.for", fixes: wantFixes},
		{source: "a.func", fixes: wantFixes},
		{source: "a.go", fixes: wantFixes},
		{source: "a.goto", fixes: wantFixes},
		{source: "a.if", fixes: wantFixes},
		{source: "a.import", fixes: wantFixes},
		{source: "a.interface", fixes: wantFixes},
		{source: "a.map", fixes: wantFixes},
		{source: "a.package", fixes: wantFixes},
		{source: "a.range", fixes: wantFixes},
		{source: "a.return", fixes: wantFixes},
		{source: "a.select", fixes: wantFixes},
		{source: "a.struct", fixes: wantFixes},
		{source: "a.switch", fixes: wantFixes},
		{source: "a.type", fixes: wantFixes},
		{source: "a.var", fixes: wantFixes},

		{source: "break.break"},
		{source: "a.BREAK"},
		{source: "a.break_"},
		{source: "a.breaka"},
	}

	for _, tc := range testCases {
		t.Run(tc.source, func(t *testing.T) {
			src := filesrc(tc.source)
			pgf, fixes := parsego.Parse(context.Background(), token.NewFileSet(), "file://foo.go", src, parsego.Full, false)
			if !slices.Equal(fixes, tc.fixes) {
				t.Fatalf("got %v want %v", fixes, tc.fixes)
			}

			// some fixes don't fit the fix scenario, but we want to confirm it.
			if fixes == nil {
				return
			}

			// ensure the selector has been converted to underscore by parser.
			ensureSource(t, src, func(sel *ast.SelectorExpr) {
				if sel.Sel.Name != "_" {
					t.Errorf("%s: selector name is %q, want _", tc.source, sel.Sel.Name)
				}
			})

			fset := tokeninternal.FileSetFor(pgf.Tok)
			inspect(t, pgf, func(sel *ast.SelectorExpr) {
				// the fix should restore the selector as is.
				if got, want := astutil.Format(fset, sel), tc.source; got != want {
					t.Fatalf("got %v want %v", got, want)
				}
			})
		})
	}
}

// inspect helps to go through each node of pgf and trigger checkFn if the type matches T.
func inspect[T ast.Node](t *testing.T, pgf *parsego.File, checkFn func(n T)) {
	fset := tokeninternal.FileSetFor(pgf.Tok)
	var visited bool
	ast.Inspect(pgf.File, func(node ast.Node) bool {
		if node != nil {
			posn := safetoken.StartPosition(fset, node.Pos())
			if !posn.IsValid() {
				t.Fatalf("invalid position for %T (%v): %v not in [%d, %d]", node, node, node.Pos(), pgf.Tok.Base(), pgf.Tok.Base()+pgf.Tok.Size())
			}
			if n, ok := node.(T); ok {
				visited = true
				checkFn(n)
			}
		}
		return true
	})
	if !visited {
		var n T
		t.Fatalf("got no %s node but want at least one", reflect.TypeOf(n))
	}
}

// ensureSource helps to parse src into an ast.File by go/parser and trigger checkFn if the type matches T.
func ensureSource[T ast.Node](t *testing.T, src []byte, checkFn func(n T)) {
	// tolerate error as usually the src is problematic.
	originFile, _ := parser.ParseFile(token.NewFileSet(), "file://foo.go", src, parsego.Full)
	var visited bool
	ast.Inspect(originFile, func(node ast.Node) bool {
		if n, ok := node.(T); ok {
			visited = true
			checkFn(n)
		}
		return true
	})

	if !visited {
		var n T
		t.Fatalf("got no %s node but want at least one", reflect.TypeOf(n))
	}
}

func filesrc(expressions string) []byte {
	const srcTmpl = `package foo

func _() {
	%s
}`
	return fmt.Appendf(nil, srcTmpl, expressions)
}


================================================
FILE: gopls/internal/cache/parsego/resolver.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by resolver_gen.go. DO NOT EDIT.

package parsego

import (
	"fmt"
	"go/ast"
	"go/token"
	"strings"
)

const debugResolve = false

// resolveFile walks the given file to resolve identifiers within the file
// scope, updating ast.Ident.Obj fields with declaration information.
//
// If declErr is non-nil, it is used to report declaration errors during
// resolution. tok is used to format position in error messages.
func resolveFile(file *ast.File, handle *token.File, declErr func(token.Pos, string)) {
	pkgScope := ast.NewScope(nil)
	r := &resolver{
		handle:   handle,
		declErr:  declErr,
		topScope: pkgScope,
		pkgScope: pkgScope,
		depth:    1,
	}

	for _, decl := range file.Decls {
		ast.Walk(r, decl)
	}

	r.closeScope()
	assert(r.topScope == nil, "unbalanced scopes")
	assert(r.labelScope == nil, "unbalanced label scopes")

	// resolve global identifiers within the same file
	i := 0
	for _, ident := range r.unresolved {
		// i <= index for current ident
		assert(ident.Obj == unresolved, "object already resolved")
		ident.Obj = r.pkgScope.Lookup(ident.Name) // also removes unresolved sentinel
		if ident.Obj == nil {
			r.unresolved[i] = ident
			i++
		} else if debugResolve {
			pos := ident.Obj.Decl.(interface{ Pos() token.Pos }).Pos()
			r.trace("resolved %s@%v to package object %v", ident.Name, ident.Pos(), pos)
		}
	}
	file.Scope = r.pkgScope
	file.Unresolved = r.unresolved[0:i]
}

const maxScopeDepth int = 1e3

type resolver struct {
	handle  *token.File
	declErr func(token.Pos, string)

	// Ordinary identifier scopes
	pkgScope   *ast.Scope   // pkgScope.Outer == nil
	topScope   *ast.Scope   // top-most scope; may be pkgScope
	unresolved []*ast.Ident // unresolved identifiers
	depth      int          // scope depth

	// Label scopes
	// (maintained by open/close LabelScope)
	labelScope  *ast.Scope     // label scope for current function
	targetStack [][]*ast.Ident // stack of unresolved labels
}

func (r *resolver) trace(format string, args ...any) {
	fmt.Println(strings.Repeat(". ", r.depth) + r.sprintf(format, args...))
}

func (r *resolver) sprintf(format string, args ...any) string {
	for i, arg := range args {
		switch arg := arg.(type) {
		case token.Pos:
			args[i] = r.handle.Position(arg)
		}
	}
	return fmt.Sprintf(format, args...)
}

func (r *resolver) openScope(pos token.Pos) {
	r.depth++
	if r.depth > maxScopeDepth {
		panic(bailout{pos: pos, msg: "exceeded max scope depth during object resolution"})
	}
	if debugResolve {
		r.trace("opening scope @%v", pos)
	}
	r.topScope = ast.NewScope(r.topScope)
}

func (r *resolver) closeScope() {
	r.depth--
	if debugResolve {
		r.trace("closing scope")
	}
	r.topScope = r.topScope.Outer
}

func (r *resolver) openLabelScope() {
	r.labelScope = ast.NewScope(r.labelScope)
	r.targetStack = append(r.targetStack, nil)
}

func (r *resolver) closeLabelScope() {
	// resolve labels
	n := len(r.targetStack) - 1
	scope := r.labelScope
	for _, ident := range r.targetStack[n] {
		ident.Obj = scope.Lookup(ident.Name)
		if ident.Obj == nil && r.declErr != nil {
			r.declErr(ident.Pos(), fmt.Sprintf("label %s undefined", ident.Name))
		}
	}
	// pop label scope
	r.targetStack = r.targetStack[0:n]
	r.labelScope = r.labelScope.Outer
}

func (r *resolver) declare(decl, data any, scope *ast.Scope, kind ast.ObjKind, idents ...*ast.Ident) {
	for _, ident := range idents {
		if ident.Obj != nil {
			panic(fmt.Sprintf("%v: identifier %s already declared or resolved", ident.Pos(), ident.Name))
		}
		obj := ast.NewObj(kind, ident.Name)
		// remember the corresponding declaration for redeclaration
		// errors and global variable resolution/typechecking phase
		obj.Decl = decl
		obj.Data = data
		// Identifiers (for receiver type parameters) are written to the scope, but
		// never set as the resolved object. See go.dev/issue/50956.
		if _, ok := decl.(*ast.Ident); !ok {
			ident.Obj = obj
		}
		if ident.Name != "_" {
			if debugResolve {
				r.trace("declaring %s@%v", ident.Name, ident.Pos())
			}
			if alt := scope.Insert(obj); alt != nil && r.declErr != nil {
				prevDecl := ""
				if pos := alt.Pos(); pos.IsValid() {
					prevDecl = r.sprintf("\n\tprevious declaration at %v", pos)
				}
				r.declErr(ident.Pos(), fmt.Sprintf("%s redeclared in this block%s", ident.Name, prevDecl))
			}
		}
	}
}

func (r *resolver) shortVarDecl(decl *ast.AssignStmt) {
	// Go spec: A short variable declaration may redeclare variables
	// provided they were originally declared in the same block with
	// the same type, and at least one of the non-blank variables is new.
	n := 0 // number of new variables
	for _, x := range decl.Lhs {
		if ident, isIdent := x.(*ast.Ident); isIdent {
			assert(ident.Obj == nil, "identifier already declared or resolved")
			obj := ast.NewObj(ast.Var, ident.Name)
			// remember corresponding assignment for other tools
			obj.Decl = decl
			ident.Obj = obj
			if ident.Name != "_" {
				if debugResolve {
					r.trace("declaring %s@%v", ident.Name, ident.Pos())
				}
				if alt := r.topScope.Insert(obj); alt != nil {
					ident.Obj = alt // redeclaration
				} else {
					n++ // new declaration
				}
			}
		}
	}
	if n == 0 && r.declErr != nil {
		r.declErr(decl.Lhs[0].Pos(), "no new variables on left side of :=")
	}
}

// The unresolved object is a sentinel to mark identifiers that have been added
// to the list of unresolved identifiers. The sentinel is only used for verifying
// internal consistency.
var unresolved = new(ast.Object)

// If x is an identifier, resolve attempts to resolve x by looking up
// the object it denotes. If no object is found and collectUnresolved is
// set, x is marked as unresolved and collected in the list of unresolved
// identifiers.
func (r *resolver) resolve(ident *ast.Ident, collectUnresolved bool) {
	if ident.Obj != nil {
		panic(r.sprintf("%v: identifier %s already declared or resolved", ident.Pos(), ident.Name))
	}
	// '_' should never refer to existing declarations, because it has special
	// handling in the spec.
	if ident.Name == "_" {
		return
	}
	for s := r.topScope; s != nil; s = s.Outer {
		if obj := s.Lookup(ident.Name); obj != nil {
			if debugResolve {
				r.trace("resolved %v:%s to %v", ident.Pos(), ident.Name, obj)
			}
			assert(obj.Name != "", "obj with no name")
			// Identifiers (for receiver type parameters) are written to the scope,
			// but never set as the resolved object. See go.dev/issue/50956.
			if _, ok := obj.Decl.(*ast.Ident); !ok {
				ident.Obj = obj
			}
			return
		}
	}
	// all local scopes are known, so any unresolved identifier
	// must be found either in the file scope, package scope
	// (perhaps in another file), or universe scope --- collect
	// them so that they can be resolved later
	if collectUnresolved {
		ident.Obj = unresolved
		r.unresolved = append(r.unresolved, ident)
	}
}

func (r *resolver) walkExprs(list []ast.Expr) {
	for _, node := range list {
		ast.Walk(r, node)
	}
}

func (r *resolver) walkLHS(list []ast.Expr) {
	for _, expr := range list {
		expr := ast.Unparen(expr)
		if _, ok := expr.(*ast.Ident); !ok && expr != nil {
			ast.Walk(r, expr)
		}
	}
}

func (r *resolver) walkStmts(list []ast.Stmt) {
	for _, stmt := range list {
		ast.Walk(r, stmt)
	}
}

func (r *resolver) Visit(node ast.Node) ast.Visitor {
	if debugResolve && node != nil {
		r.trace("node %T@%v", node, node.Pos())
	}

	switch n := node.(type) {

	// Expressions.
	case *ast.Ident:
		r.resolve(n, true)

	case *ast.FuncLit:
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkFuncType(n.Type)
		r.walkBody(n.Body)

	case *ast.SelectorExpr:
		ast.Walk(r, n.X)
		// Note: don't try to resolve n.Sel, as we don't support qualified
		// resolution.

	case *ast.StructType:
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkFieldList(n.Fields, ast.Var)

	case *ast.FuncType:
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkFuncType(n)

	case *ast.CompositeLit:
		if n.Type != nil {
			ast.Walk(r, n.Type)
		}
		for _, e := range n.Elts {
			if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
				// See go.dev/issue/45160: try to resolve composite lit keys, but don't
				// collect them as unresolved if resolution failed. This replicates
				// existing behavior when resolving during parsing.
				if ident, _ := kv.Key.(*ast.Ident); ident != nil {
					r.resolve(ident, false)
				} else {
					ast.Walk(r, kv.Key)
				}
				ast.Walk(r, kv.Value)
			} else {
				ast.Walk(r, e)
			}
		}

	case *ast.InterfaceType:
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkFieldList(n.Methods, ast.Fun)

	// Statements
	case *ast.LabeledStmt:
		r.declare(n, nil, r.labelScope, ast.Lbl, n.Label)
		ast.Walk(r, n.Stmt)

	case *ast.AssignStmt:
		r.walkExprs(n.Rhs)
		if n.Tok == token.DEFINE {
			r.shortVarDecl(n)
		} else {
			r.walkExprs(n.Lhs)
		}

	case *ast.BranchStmt:
		// add to list of unresolved targets
		if n.Tok != token.FALLTHROUGH && n.Label != nil {
			depth := len(r.targetStack) - 1
			r.targetStack[depth] = append(r.targetStack[depth], n.Label)
		}

	case *ast.BlockStmt:
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkStmts(n.List)

	case *ast.IfStmt:
		r.openScope(n.Pos())
		defer r.closeScope()
		if n.Init != nil {
			ast.Walk(r, n.Init)
		}
		ast.Walk(r, n.Cond)
		ast.Walk(r, n.Body)
		if n.Else != nil {
			ast.Walk(r, n.Else)
		}

	case *ast.CaseClause:
		r.walkExprs(n.List)
		r.openScope(n.Pos())
		defer r.closeScope()
		r.walkStmts(n.Body)

	case *ast.SwitchStmt:
		r.openScope(n.Pos())
		defer r.closeScope()
		if n.Init != nil {
			ast.Walk(r, n.Init)
		}
		if n.Tag != nil {
			// The scope below reproduces some unnecessary behavior of the parser,
			// opening an extra scope in case this is a type switch. It's not needed
			// for expression switches.
			// TODO: remove this once we've matched the parser resolution exactly.
			if n.Init != nil {
				r.openScope(n.Tag.Pos())
				defer r.closeScope()
			}
			ast.Walk(r, n.Tag)
		}
		if n.Body != nil {
			r.walkStmts(n.Body.List)
		}

	case *ast.TypeSwitchStmt:
		if n.Init != nil {
			r.openScope(n.Pos())
			defer r.closeScope()
			ast.Walk(r, n.Init)
		}
		r.openScope(n.Assign.Pos())
		defer r.closeScope()
		ast.Walk(r, n.Assign)
		// s.Body consists only of case clauses, so does not get its own
		// scope.
		if n.Body != nil {
			r.walkStmts(n.Body.List)
		}

	case *ast.CommClause:
		r.openScope(n.Pos())
		defer r.closeScope()
		if n.Comm != nil {
			ast.Walk(r, n.Comm)
		}
		r.walkStmts(n.Body)

	case *ast.SelectStmt:
		// as for switch statements, select statement bodies don't get their own
		// scope.
		if n.Body != nil {
			r.walkStmts(n.Body.List)
		}

	case *ast.ForStmt:
		r.openScope(n.Pos())
		defer r.closeScope()
		if n.Init != nil {
			ast.Walk(r, n.Init)
		}
		if n.Cond != nil {
			ast.Walk(r, n.Cond)
		}
		if n.Post != nil {
			ast.Walk(r, n.Post)
		}
		ast.Walk(r, n.Body)

	case *ast.RangeStmt:
		r.openScope(n.Pos())
		defer r.closeScope()
		ast.Walk(r, n.X)
		var lhs []ast.Expr
		if n.Key != nil {
			lhs = append(lhs, n.Key)
		}
		if n.Value != nil {
			lhs = append(lhs, n.Value)
		}
		if len(lhs) > 0 {
			if n.Tok == token.DEFINE {
				// Note: we can't exactly match the behavior of object resolution
				// during the parsing pass here, as it uses the position of the RANGE
				// token for the RHS OpPos. That information is not contained within
				// the AST.
				as := &ast.AssignStmt{
					Lhs:    lhs,
					Tok:    token.DEFINE,
					TokPos: n.TokPos,
					Rhs:    []ast.Expr{&ast.UnaryExpr{Op: token.RANGE, X: n.X}},
				}
				// TODO(rFindley): this walkLHS reproduced the parser resolution, but
				// is it necessary? By comparison, for a normal AssignStmt we don't
				// walk the LHS in case there is an invalid identifier list.
				r.walkLHS(lhs)
				r.shortVarDecl(as)
			} else {
				r.walkExprs(lhs)
			}
		}
		ast.Walk(r, n.Body)

	// Declarations
	case *ast.GenDecl:
		switch n.Tok {
		case token.CONST, token.VAR:
			for i, spec := range n.Specs {
				spec := spec.(*ast.ValueSpec)
				kind := ast.Con
				if n.Tok == token.VAR {
					kind = ast.Var
				}
				r.walkExprs(spec.Values)
				if spec.Type != nil {
					ast.Walk(r, spec.Type)
				}
				r.declare(spec, i, r.topScope, kind, spec.Names...)
			}
		case token.TYPE:
			for _, spec := range n.Specs {
				spec := spec.(*ast.TypeSpec)
				// Go spec: The scope of a type identifier declared inside a function begins
				// at the identifier in the TypeSpec and ends at the end of the innermost
				// containing block.
				r.declare(spec, nil, r.topScope, ast.Typ, spec.Name)
				if spec.TypeParams != nil {
					r.openScope(spec.Pos())
					defer r.closeScope()
					r.walkTParams(spec.TypeParams)
				}
				ast.Walk(r, spec.Type)
			}
		}

	case *ast.FuncDecl:
		// Open the function scope.
		r.openScope(n.Pos())
		defer r.closeScope()

		r.walkRecv(n.Recv)

		// Type parameters are walked normally: they can reference each other, and
		// can be referenced by normal parameters.
		if n.Type.TypeParams != nil {
			r.walkTParams(n.Type.TypeParams)
			// TODO(rFindley): need to address receiver type parameters.
		}

		// Resolve and declare parameters in a specific order to get duplicate
		// declaration errors in the correct location.
		r.resolveList(n.Type.Params)
		r.resolveList(n.Type.Results)
		r.declareList(n.Recv, ast.Var)
		r.declareList(n.Type.Params, ast.Var)
		r.declareList(n.Type.Results, ast.Var)

		r.walkBody(n.Body)
		if n.Recv == nil && n.Name.Name != "init" {
			r.declare(n, nil, r.pkgScope, ast.Fun, n.Name)
		}

	default:
		return r
	}

	return nil
}

func (r *resolver) walkFuncType(typ *ast.FuncType) {
	// typ.TypeParams must be walked separately for FuncDecls.
	r.resolveList(typ.Params)
	r.resolveList(typ.Results)
	r.declareList(typ.Params, ast.Var)
	r.declareList(typ.Results, ast.Var)
}

func (r *resolver) resolveList(list *ast.FieldList) {
	if list == nil {
		return
	}
	for _, f := range list.List {
		if f.Type != nil {
			ast.Walk(r, f.Type)
		}
	}
}

func (r *resolver) declareList(list *ast.FieldList, kind ast.ObjKind) {
	if list == nil {
		return
	}
	for _, f := range list.List {
		r.declare(f, nil, r.topScope, kind, f.Names...)
	}
}

func (r *resolver) walkRecv(recv *ast.FieldList) {
	// If our receiver has receiver type parameters, we must declare them before
	// trying to resolve the rest of the receiver, and avoid re-resolving the
	// type parameter identifiers.
	if recv == nil || len(recv.List) == 0 {
		return // nothing to do
	}
	typ := recv.List[0].Type
	if ptr, ok := typ.(*ast.StarExpr); ok {
		typ = ptr.X
	}

	var declareExprs []ast.Expr // exprs to declare
	var resolveExprs []ast.Expr // exprs to resolve
	switch typ := typ.(type) {
	case *ast.IndexExpr:
		declareExprs = []ast.Expr{typ.Index}
		resolveExprs = append(resolveExprs, typ.X)
	case *ast.IndexListExpr:
		declareExprs = typ.Indices
		resolveExprs = append(resolveExprs, typ.X)
	default:
		resolveExprs = append(resolveExprs, typ)
	}
	for _, expr := range declareExprs {
		if id, _ := expr.(*ast.Ident); id != nil {
			r.declare(expr, nil, r.topScope, ast.Typ, id)
		} else {
			// The receiver type parameter expression is invalid, but try to resolve
			// it anyway for consistency.
			resolveExprs = append(resolveExprs, expr)
		}
	}
	for _, expr := range resolveExprs {
		if expr != nil {
			ast.Walk(r, expr)
		}
	}
	// The receiver is invalid, but try to resolve it anyway for consistency.
	for _, f := range recv.List[1:] {
		if f.Type != nil {
			ast.Walk(r, f.Type)
		}
	}
}

func (r *resolver) walkFieldList(list *ast.FieldList, kind ast.ObjKind) {
	if list == nil {
		return
	}
	r.resolveList(list)
	r.declareList(list, kind)
}

// walkTParams is like walkFieldList, but declares type parameters eagerly so
// that they may be resolved in the constraint expressions held in the field
// Type.
func (r *resolver) walkTParams(list *ast.FieldList) {
	r.declareList(list, ast.Typ)
	r.resolveList(list)
}

func (r *resolver) walkBody(body *ast.BlockStmt) {
	if body == nil {
		return
	}
	r.openLabelScope()
	defer r.closeLabelScope()
	r.walkStmts(body.List)
}


================================================
FILE: gopls/internal/cache/parsego/resolver_compat.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains declarations needed for compatibility with resolver.go
// copied from GOROOT.

package parsego

import "go/token"

// assert panics with the given msg if cond is not true.
func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

// A bailout panic is raised to indicate early termination. pos and msg are
// only populated when bailing out of object resolution.
type bailout struct {
	pos token.Pos
	msg string
}


================================================
FILE: gopls/internal/cache/parsego/resolver_gen.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

package main

import (
	"bytes"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

func main() {
	output, err := exec.Command("go", "env", "GOROOT").Output()
	if err != nil {
		log.Fatalf("resolving GOROOT: %v", err)
	}
	goroot := strings.TrimSpace(string(output))
	data, err := os.ReadFile(filepath.Join(goroot, "src/go/parser/resolver.go"))
	if err != nil {
		log.Fatalf("reading resolver.go: %v", err)
	}
	data = bytes.Replace(data, []byte("\npackage parser"), []byte("\n// Code generated by resolver_gen.go. DO NOT EDIT.\n\npackage parsego"), 1)
	if err := os.WriteFile("resolver.go", data, 0666); err != nil {
		log.Fatalf("writing resolver.go: %v", err)
	}
}


================================================
FILE: gopls/internal/cache/parsego/resolver_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package parsego

import (
	"go/ast"
	"go/types"
	"os"
	"strings"
	"testing"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/testenv"
)

// TestGoplsSourceDoesNotUseObjectResolution verifies that gopls does not
// read fields that are set during syntactic object resolution, except in
// locations where we can guarantee that object resolution has occurred. This
// is achieved via static analysis of gopls source code to find references to
// the legacy Object symbols, checking the results against an allowlist
//
// Reading these fields would introduce a data race, due to the lazy
// resolution implemented by File.Resolve.
func TestGoplsSourceDoesNotUseObjectResolution(t *testing.T) {

	testenv.NeedsGoPackages(t)
	testenv.NeedsLocalXTools(t)

	cfg := &packages.Config{
		Mode: packages.NeedName | packages.NeedModule | packages.NeedCompiledGoFiles | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedImports | packages.NeedDeps,
	}
	cfg.Env = os.Environ()
	cfg.Env = append(cfg.Env,
		"GOPACKAGESDRIVER=off",
		"GOWORK=off", // necessary for -mod=mod below
		"GOFLAGS=-mod=mod",
	)

	pkgs, err := packages.Load(cfg,
		"go/ast",
		"golang.org/x/tools/go/ast/astutil",
		"golang.org/x/tools/gopls/...")

	if err != nil {
		t.Fatal(err)
	}
	var astPkg, astutilPkg *packages.Package
	for _, pkg := range pkgs {
		switch pkg.PkgPath {
		case "go/ast":
			astPkg = pkg
		case "golang.org/x/tools/go/ast/astutil":
			astutilPkg = pkg
		}
	}
	if astPkg == nil {
		t.Fatal("missing package go/ast")
	}
	if astutilPkg == nil {
		t.Fatal("missing package golang.org/x/tools/go/ast/astutil")
	}

	File := astPkg.Types.Scope().Lookup("File").Type()
	Ident := astPkg.Types.Scope().Lookup("Ident").Type()

	Scope, _, _ := types.LookupFieldOrMethod(File, true, astPkg.Types, "Scope")
	assert(Scope != nil, "nil Scope")
	Unresolved, _, _ := types.LookupFieldOrMethod(File, true, astPkg.Types, "Unresolved")
	assert(Unresolved != nil, "nil unresolved")
	Obj, _, _ := types.LookupFieldOrMethod(Ident, true, astPkg.Types, "Obj")
	assert(Obj != nil, "nil Obj")
	UsesImport := astutilPkg.Types.Scope().Lookup("UsesImport")
	assert(UsesImport != nil, "nil UsesImport")

	disallowed := map[types.Object]bool{
		Scope:      true,
		Unresolved: true,
		Obj:        true,
		UsesImport: true,
	}

	// exceptions catalogues packages or declarations that are allowed to use
	// forbidden symbols, with a rationale.
	//
	// - If the exception ends with '/', it is a prefix.
	// - If it ends with a qualified name, it is a declaration.
	// - Otherwise, it is an exact package path.
	//
	// TODO(rfindley): some sort of callgraph analysis would make these
	// exceptions much easier to maintain.
	exceptions := []string{
		"golang.org/x/tools/go/analysis/passes/",                             // analyzers may rely on object resolution
		"golang.org/x/tools/gopls/internal/analysis/simplifyslice",           // restrict ourselves to one blessed analyzer
		"golang.org/x/tools/gopls/internal/cache/parsego",                    // used by parsego.File.Resolve, of course
		"golang.org/x/tools/gopls/internal/golang.builtinDecl",               // the builtin file is resolved
		"golang.org/x/tools/gopls/internal/golang.NewBuiltinSignature",       // ditto
		"golang.org/x/tools/gopls/internal/golang/completion.builtinArgKind", // ditto
		"golang.org/x/tools/internal/imports",                                // goimports does its own parsing
		"golang.org/x/tools/go/ast/astutil.UsesImport",                       // disallowed
		"golang.org/x/tools/go/ast/astutil.isTopName",                        // only reached from astutil.UsesImport
		"go/ast",
		"go/parser",
		"go/doc", // manually verified that our usage is safe
	}

	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		for _, exception := range exceptions {
			if strings.HasSuffix(exception, "/") {
				if strings.HasPrefix(pkg.PkgPath, exception) {
					return
				}
			} else if pkg.PkgPath == exception {
				return
			}
		}

	searchUses:
		for ident, obj := range pkg.TypesInfo.Uses {
			if disallowed[obj] {
				decl := findEnclosingFuncDecl(ident, pkg)
				if decl == "" {
					posn := safetoken.Position(pkg.Fset.File(ident.Pos()), ident.Pos())
					t.Fatalf("%s: couldn't find enclosing decl for use of %s", posn, ident.Name)
				}
				qualified := pkg.PkgPath + "." + decl
				for _, exception := range exceptions {
					if exception == qualified {
						continue searchUses
					}
				}
				posn := safetoken.StartPosition(pkg.Fset, ident.Pos())
				t.Errorf("%s: forbidden use of %v in %s", posn, obj, qualified)
			}
		}
	})
}

// findEnclosingFuncDecl finds the name of the func decl enclosing the usage,
// or "".
//
// (Usage could theoretically exist in e.g. var initializers, but that would be
// odd.)
func findEnclosingFuncDecl(ident *ast.Ident, pkg *packages.Package) string {
	for _, file := range pkg.Syntax {
		if file.FileStart <= ident.Pos() && ident.Pos() < file.FileEnd {
			path, _ := astutil.PathEnclosingInterval(file, ident.Pos(), ident.End())
			decl, ok := path[len(path)-2].(*ast.FuncDecl)
			if ok {
				return decl.Name.Name
			}
		}
	}
	return ""
}


================================================
FILE: gopls/internal/cache/port.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"go/build"
	"go/build/constraint"
	"go/parser"
	"go/token"
	"io"
	"path/filepath"
	"strings"

	"golang.org/x/tools/gopls/internal/util/bug"
)

type port struct{ GOOS, GOARCH string }

var (
	// preferredPorts holds GOOS/GOARCH combinations for which we dynamically
	// create new Views, by setting GOOS=... and GOARCH=... on top of
	// user-provided configuration when we detect that the default build
	// configuration does not match an open file. Ports are matched in the order
	// defined below, so that when multiple ports match a file we use the port
	// occurring at a lower index in the slice. For that reason, we sort first
	// class ports ahead of secondary ports, and (among first class ports) 64-bit
	// ports ahead of the less common 32-bit ports.
	preferredPorts = []port{
		// First class ports, from https://go.dev/wiki/PortingPolicy.
		{"darwin", "amd64"},
		{"darwin", "arm64"},
		{"linux", "amd64"},
		{"linux", "arm64"},
		{"windows", "amd64"},
		{"linux", "arm"},
		{"linux", "386"},
		{"windows", "386"},

		// Secondary ports, from GOROOT/src/internal/platform/zosarch.go.
		// (First class ports are commented out.)
		{"aix", "ppc64"},
		{"dragonfly", "amd64"},
		{"freebsd", "386"},
		{"freebsd", "amd64"},
		{"freebsd", "arm"},
		{"freebsd", "arm64"},
		{"illumos", "amd64"},
		{"linux", "ppc64"},
		{"linux", "ppc64le"},
		{"linux", "mips"},
		{"linux", "mipsle"},
		{"linux", "mips64"},
		{"linux", "mips64le"},
		{"linux", "riscv64"},
		{"linux", "s390x"},
		{"android", "386"},
		{"android", "amd64"},
		{"android", "arm"},
		{"android", "arm64"},
		{"ios", "arm64"},
		{"ios", "amd64"},
		{"js", "wasm"},
		{"netbsd", "386"},
		{"netbsd", "amd64"},
		{"netbsd", "arm"},
		{"netbsd", "arm64"},
		{"openbsd", "386"},
		{"openbsd", "amd64"},
		{"openbsd", "arm"},
		{"openbsd", "arm64"},
		{"openbsd", "mips64"},
		{"plan9", "386"},
		{"plan9", "amd64"},
		{"plan9", "arm"},
		{"solaris", "amd64"},
		{"windows", "arm"},
		{"windows", "arm64"},

		{"aix", "ppc64"},
		{"android", "386"},
		{"android", "amd64"},
		{"android", "arm"},
		{"android", "arm64"},
		// {"darwin", "amd64"},
		// {"darwin", "arm64"},
		{"dragonfly", "amd64"},
		{"freebsd", "386"},
		{"freebsd", "amd64"},
		{"freebsd", "arm"},
		{"freebsd", "arm64"},
		{"freebsd", "riscv64"},
		{"illumos", "amd64"},
		{"ios", "amd64"},
		{"ios", "arm64"},
		{"js", "wasm"},
		// {"linux", "386"},
		// {"linux", "amd64"},
		// {"linux", "arm"},
		// {"linux", "arm64"},
		{"linux", "loong64"},
		{"linux", "mips"},
		{"linux", "mips64"},
		{"linux", "mips64le"},
		{"linux", "mipsle"},
		{"linux", "ppc64"},
		{"linux", "ppc64le"},
		{"linux", "riscv64"},
		{"linux", "s390x"},
		{"linux", "sparc64"},
		{"netbsd", "386"},
		{"netbsd", "amd64"},
		{"netbsd", "arm"},
		{"netbsd", "arm64"},
		{"openbsd", "386"},
		{"openbsd", "amd64"},
		{"openbsd", "arm"},
		{"openbsd", "arm64"},
		{"openbsd", "mips64"},
		{"openbsd", "ppc64"},
		{"openbsd", "riscv64"},
		{"plan9", "386"},
		{"plan9", "amd64"},
		{"plan9", "arm"},
		{"solaris", "amd64"},
		{"wasip1", "wasm"},
		// {"windows", "386"},
		// {"windows", "amd64"},
		{"windows", "arm"},
		{"windows", "arm64"},
	}
)

// matches reports whether the port matches a file with the given absolute path
// and content.
//
// Note that this function accepts content rather than e.g. a file.Handle,
// because we trim content before matching for performance reasons, and
// therefore need to do this outside of matches when considering multiple ports.
func (p port) matches(path string, content []byte) bool {
	ctxt := build.Default // make a copy
	ctxt.UseAllFiles = false
	path = filepath.Clean(path)
	if !filepath.IsAbs(path) {
		bug.Reportf("non-abs file path %q", path)
		return false // fail closed
	}
	dir, name := filepath.Split(path)

	// The only virtualized operation called by MatchFile is OpenFile.
	ctxt.OpenFile = func(p string) (io.ReadCloser, error) {
		if p != path {
			return nil, bug.Errorf("unexpected file %q", p)
		}
		return io.NopCloser(bytes.NewReader(content)), nil
	}

	ctxt.GOOS = p.GOOS
	ctxt.GOARCH = p.GOARCH
	ok, err := ctxt.MatchFile(dir, name)
	return err == nil && ok
}

// trimContentForPortMatch trims the given Go file content to a minimal file
// containing the same build constraints, if any.
//
// This is an unfortunate but necessary optimization, as matching build
// constraints using go/build has significant overhead, and involves parsing
// more than just the build constraint.
//
// TestMatchingPortsConsistency enforces consistency by comparing results
// without trimming content.
func trimContentForPortMatch(content []byte) []byte {
	buildComment := buildComment(content)
	// The package name does not matter, but +build lines
	// require a blank line before the package declaration.
	return []byte(buildComment + "\n\npackage p")
}

// buildComment returns the first matching //go:build comment in the given
// content, or "" if none exists.
func buildComment(content []byte) string {
	var lines []string

	f, err := parser.ParseFile(token.NewFileSet(), "", content, parser.PackageClauseOnly|parser.ParseComments)
	if err != nil {
		return ""
	}

	for _, cg := range f.Comments {
		for _, c := range cg.List {
			if constraint.IsGoBuild(c.Text) {
				// A file must have only one //go:build line.
				return c.Text
			}
			if constraint.IsPlusBuild(c.Text) {
				// A file may have several // +build lines.
				lines = append(lines, c.Text)
			}
		}
	}
	return strings.Join(lines, "\n")
}


================================================
FILE: gopls/internal/cache/port_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"os"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(m.Run())
}

func TestMatchingPortsStdlib(t *testing.T) {
	// This test checks that we don't encounter a bug when matching ports, and
	// sanity checks that the optimization to use trimmed/fake file content
	// before delegating to go/build.Context.MatchFile does not affect
	// correctness.
	if testing.Short() {
		t.Skip("skipping in short mode: takes to long on slow file systems")
	}

	testenv.NeedsTool(t, "go")

	// Load, parse and type-check the program.
	cfg := &packages.Config{
		Mode:  packages.LoadFiles,
		Tests: true,
	}
	pkgs, err := packages.Load(cfg, "std", "cmd")
	if err != nil {
		t.Fatal(err)
	}

	var g errgroup.Group
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		for _, f := range pkg.CompiledGoFiles {
			g.Go(func() error {
				content, err := os.ReadFile(f)
				// We report errors via t.Error, not by returning,
				// so that a single test can report multiple test failures.
				if err != nil {
					t.Errorf("failed to read %s: %v", f, err)
					return nil
				}
				fh := makeFakeFileHandle(protocol.URIFromPath(f), content)
				fastPorts := matchingPreferredPorts(t, fh, true)
				slowPorts := matchingPreferredPorts(t, fh, false)
				if diff := cmp.Diff(fastPorts, slowPorts); diff != "" {
					t.Errorf("%s: ports do not match (-trimmed +untrimmed):\n%s", f, diff)
					return nil
				}
				return nil
			})
		}
	})
	_ = g.Wait() // can't fail
}

func matchingPreferredPorts(tb testing.TB, fh file.Handle, trimContent bool) map[port]unit {
	content, err := fh.Content()
	if err != nil {
		tb.Fatal(err)
	}
	if trimContent {
		content = trimContentForPortMatch(content)
	}
	path := fh.URI().Path()
	matching := make(map[port]unit)
	for _, port := range preferredPorts {
		if port.matches(path, content) {
			matching[port] = unit{}
		}
	}
	return matching
}

func BenchmarkMatchingPreferredPorts(b *testing.B) {
	// Copy of robustio_posix.go
	const src = `
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build unix
// +build unix

package robustio

import (
	"os"
	"syscall"
	"time"
)

func getFileID(filename string) (FileID, time.Time, error) {
	fi, err := os.Stat(filename)
	if err != nil {
		return FileID{}, time.Time{}, err
	}
	stat := fi.Sys().(*syscall.Stat_t)
	return FileID{
		device: uint64(stat.Dev), // (int32 on darwin, uint64 on linux)
		inode:  stat.Ino,
	}, fi.ModTime(), nil
}
`
	fh := makeFakeFileHandle("file:///path/to/test/file.go", []byte(src))
	for b.Loop() {
		_ = matchingPreferredPorts(b, fh, true)
	}
}


================================================
FILE: gopls/internal/cache/session.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"errors"
	"fmt"
	"maps"
	"os"
	"path/filepath"
	"slices"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/gopls/internal/util/persistent"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/xcontext"
)

// NewSession creates a new gopls session with the given cache.
func NewSession(ctx context.Context, c *Cache) *Session {
	index := atomic.AddInt64(&sessionIndex, 1)
	s := &Session{
		id:          strconv.FormatInt(index, 10),
		cache:       c,
		gocmdRunner: &gocommand.Runner{},
		overlayFS:   newOverlayFS(c),
		parseCache:  newParseCache(1 * time.Minute), // keep recently parsed files for a minute, to optimize typing CPU
		viewMap:     make(map[protocol.DocumentURI]*View),
	}
	event.Log(ctx, "New session", KeyCreateSession.Of(s))
	return s
}

// A Session holds the state (views, file contents, parse cache,
// memoized computations) of a gopls server process.
//
// It implements the file.Source interface.
type Session struct {
	// Unique identifier for this session.
	id string

	// Immutable attributes shared across views.
	cache       *Cache            // shared cache
	gocmdRunner *gocommand.Runner // limits go command concurrency

	viewMu  sync.Mutex
	views   []*View
	viewMap map[protocol.DocumentURI]*View // file->best view or nil; nil after shutdown; the key must be a clean uri.

	// snapshots is a counting semaphore that records the number
	// of unreleased snapshots associated with this session.
	// Shutdown waits for it to fall to zero.
	snapshotWG sync.WaitGroup

	parseCache *parseCache

	*overlayFS
}

// ID returns the unique identifier for this session on this server.
func (s *Session) ID() string     { return s.id }
func (s *Session) String() string { return s.id }

// GoCommandRunner returns the gocommand Runner for this session.
func (s *Session) GoCommandRunner() *gocommand.Runner {
	return s.gocmdRunner
}

// Shutdown the session and all views it has created.
func (s *Session) Shutdown(ctx context.Context) {
	var views []*View
	s.viewMu.Lock()
	views = append(views, s.views...)
	s.views = nil
	s.viewMap = nil
	s.viewMu.Unlock()
	for _, view := range views {
		view.shutdown()
	}
	s.parseCache.stop()
	s.snapshotWG.Wait() // wait for all work on associated snapshots to finish
	event.Log(ctx, "Shutdown session", KeyShutdownSession.Of(s))
}

// Cache returns the cache that created this session, for debugging only.
func (s *Session) Cache() *Cache {
	return s.cache
}

// TODO(rfindley): is the logic surrounding this error actually necessary?
var ErrViewExists = errors.New("view already exists for session")

// NewView creates a new View, returning it and its first snapshot. If a
// non-empty tempWorkspace directory is provided, the View will record a copy
// of its gopls workspace module in that directory, so that client tooling
// can execute in the same main module.  On success it also returns a release
// function that must be called when the Snapshot is no longer needed.
func (s *Session) NewView(ctx context.Context, folder *Folder) (*View, *Snapshot, func(), error) {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	if s.viewMap == nil {
		return nil, nil, nil, fmt.Errorf("session is shut down")
	}

	// Querying the file system to check whether
	// two folders denote the same existing directory.
	if inode1, err := os.Stat(filepath.FromSlash(folder.Dir.Path())); err == nil {
		for _, view := range s.views {
			inode2, err := os.Stat(filepath.FromSlash(view.folder.Dir.Path()))
			if err == nil && os.SameFile(inode1, inode2) {
				return nil, nil, nil, ErrViewExists
			}
		}
	}

	def, err := defineView(ctx, s, folder, nil)
	if err != nil {
		return nil, nil, nil, err
	}
	view, snapshot, release := s.createView(ctx, def)
	s.views = append(s.views, view)
	s.viewMap[folder.Dir.Clean()] = view
	return view, snapshot, release, nil
}

// HasView checks whether the uri's view exists.
func (s *Session) HasView(uri protocol.DocumentURI) bool {
	uri = uri.Clean()
	s.viewMu.Lock()
	defer s.viewMu.Unlock()
	_, ok := s.viewMap[uri]
	return ok
}

// createView creates a new view, with an initial snapshot that retains the
// supplied context, detached from events and cancellation.
//
// The caller is responsible for calling the release function once.
func (s *Session) createView(ctx context.Context, def *viewDefinition) (*View, *Snapshot, func()) {
	index := atomic.AddInt64(&viewIndex, 1)

	// We want a true background context and not a detached context here
	// the spans need to be unrelated and no tag values should pollute it.
	baseCtx := event.Detach(xcontext.Detach(ctx))
	backgroundCtx, cancel := context.WithCancel(baseCtx)

	// Compute a skip function to use for module cache scanning.
	//
	// Note that unlike other filtering operations, we definitely don't want to
	// exclude the gomodcache here, even if it is contained in the workspace
	// folder.
	//
	// TODO(rfindley): consolidate with relPathExcludedByFilter(Func), Filterer,
	// View.filterFunc.
	var skipPath func(string) bool
	{
		// Compute a prefix match, respecting segment boundaries, by ensuring
		// the pattern (dir) has a trailing slash.
		dirPrefix := strings.TrimSuffix(string(def.folder.Dir), "/") + "/"
		pathIncluded := PathIncludeFunc(def.folder.Options.DirectoryFilters)
		skipPath = func(dir string) bool {
			uri := strings.TrimSuffix(string(protocol.URIFromPath(dir)), "/")
			// Note that the logic below doesn't handle the case where uri ==
			// v.folder.Dir, because there is no point in excluding the entire
			// workspace folder!
			if rel, ok := strings.CutPrefix(uri, dirPrefix); ok {
				return !pathIncluded(rel)
			}
			return false
		}
	}

	var ignoreFilter *ignoreFilter
	{
		var dirs []string
		if len(def.workspaceModFiles) == 0 {
			for _, entry := range filepath.SplitList(def.folder.Env.GOPATH) {
				dirs = append(dirs, filepath.Join(entry, "src"))
			}
		} else {
			dirs = append(dirs, def.folder.Env.GOMODCACHE)
			for m := range def.workspaceModFiles {
				dirs = append(dirs, m.DirPath())
			}
		}
		ignoreFilter = newIgnoreFilter(dirs)
	}

	var pe *imports.ProcessEnv
	{
		env := make(map[string]string)
		envSlice := slices.Concat(os.Environ(), def.folder.Options.EnvSlice(), []string{"GO111MODULE=" + def.adjustedGO111MODULE()})
		for _, kv := range envSlice {
			if k, v, ok := strings.Cut(kv, "="); ok {
				env[k] = v
			}
		}
		pe = &imports.ProcessEnv{
			GocmdRunner: s.gocmdRunner,
			BuildFlags:  slices.Clone(def.folder.Options.BuildFlags),
			// TODO(rfindley): an old comment said "processEnv operations should not mutate the modfile"
			// But shouldn't we honor the default behavior of mod vendoring?
			ModFlag:        "readonly",
			SkipPathInScan: skipPath,
			Env:            env,
			WorkingDir:     def.root.Path(),
			ModCache:       s.cache.modCache.dirCache(def.folder.Env.GOMODCACHE),
		}
		if def.folder.Options.VerboseOutput {
			pe.Logf = func(format string, args ...any) {
				event.Log(ctx, fmt.Sprintf(format, args...))
			}
		}
	}

	v := &View{
		id:                   strconv.FormatInt(index, 10),
		gocmdRunner:          s.gocmdRunner,
		initialWorkspaceLoad: make(chan struct{}),
		initializationSema:   make(chan struct{}, 1),
		baseCtx:              baseCtx,
		pkgIndex:             typerefs.NewPackageIndex(),
		parseCache:           s.parseCache,
		ignoreFilter:         ignoreFilter,
		fs:                   s.overlayFS,
		viewDefinition:       def,
		importsState:         newImportsState(backgroundCtx, s.cache.modCache, pe),
	}

	// Keep this in sync with golang.computeImportEdits.
	//
	// TODO(rfindley): encapsulate the imports state logic so that the handling
	// for Options.ImportsSource is in a single location.
	if def.folder.Options.ImportsSource == settings.ImportsSourceGopls {
		v.modcacheState = newModcacheState(def.folder.Env.GOMODCACHE)
	}

	s.snapshotWG.Add(1)
	v.snapshot = &Snapshot{
		view:              v,
		backgroundCtx:     backgroundCtx,
		cancel:            cancel,
		store:             s.cache.store,
		refcount:          1, // Snapshots are born referenced.
		done:              s.snapshotWG.Done,
		packages:          new(persistent.Map[PackageID, *packageHandle]),
		fullAnalysisKeys:  new(persistent.Map[PackageID, file.Hash]),
		factyAnalysisKeys: new(persistent.Map[PackageID, file.Hash]),
		meta:              new(metadata.Graph),
		files:             newFileMap(),
		shouldLoad:        new(persistent.Map[PackageID, []PackagePath]),
		unloadableFiles:   new(persistent.Set[protocol.DocumentURI]),
		parseModHandles:   new(persistent.Map[protocol.DocumentURI, *memoize.Promise]),
		parseWorkHandles:  new(persistent.Map[protocol.DocumentURI, *memoize.Promise]),
		modTidyHandles:    new(persistent.Map[protocol.DocumentURI, *memoize.Promise]),
		modVulnHandles:    new(persistent.Map[protocol.DocumentURI, *memoize.Promise]),
		modWhyHandles:     new(persistent.Map[protocol.DocumentURI, *memoize.Promise]),
		moduleUpgrades:    new(persistent.Map[protocol.DocumentURI, map[string]string]),
		vulns:             new(persistent.Map[protocol.DocumentURI, *vulncheck.Result]),
	}

	// Snapshots must observe all open files, as there are some caching
	// heuristics that change behavior depending on open files.
	for _, o := range s.overlayFS.Overlays() {
		_, _ = v.snapshot.ReadFile(ctx, o.URI())
	}

	// Record the environment of the newly created view in the log.
	event.Log(ctx, fmt.Sprintf("Created View (#%s)", v.id),
		label.Directory.Of(v.folder.Dir.Path()),
		viewTypeKey.Of(v.typ.String()),
		rootDirKey.Of(string(v.root)),
		goVersionKey.Of(strings.TrimRight(v.folder.Env.GoVersionOutput, "\n")),
		buildFlagsKey.Of(fmt.Sprint(v.folder.Options.BuildFlags)),
		envKey.Of(fmt.Sprintf("%+v", v.folder.Env)),
		envOverlayKey.Of(v.EnvOverlay()),
	)

	// Initialize the view without blocking.
	initCtx, initCancel := context.WithCancel(xcontext.Detach(ctx))
	v.cancelInitialWorkspaceLoad = initCancel
	snapshot := v.snapshot

	// Pass a second reference to the background goroutine.
	bgRelease := snapshot.Acquire()
	go func() {
		defer bgRelease()
		snapshot.initialize(initCtx, true)
	}()

	// Return a third reference to the caller.
	return v, snapshot, snapshot.Acquire()
}

// These keys are used to log view metadata in createView.
var (
	viewTypeKey   = keys.NewString("view_type", "")
	rootDirKey    = keys.NewString("root_dir", "")
	goVersionKey  = keys.NewString("go_version", "")
	buildFlagsKey = keys.New("build_flags", "")
	envKey        = keys.New("env", "")
	envOverlayKey = keys.New("env_overlay", "")
)

// RemoveView removes from the session the view rooted at the specified directory.
// It reports whether a view of that directory was removed.
func (s *Session) RemoveView(ctx context.Context, dir protocol.DocumentURI) bool {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	if s.viewMap == nil {
		return false // Session is shutdown.
	}
	s.viewMap = make(map[protocol.DocumentURI]*View) // reset view associations

	var newViews []*View
	for _, view := range s.views {
		if view.folder.Dir == dir {
			view.shutdown()
		} else {
			newViews = append(newViews, view)
		}
	}
	removed := len(s.views) - len(newViews)
	if removed != 1 {
		// This isn't a bug report, because it could be a client-side bug.
		event.Error(ctx, "removing view", fmt.Errorf("removed %d views, want exactly 1", removed))
	}
	s.views = newViews
	return removed > 0
}

// View returns the view with a matching id, if present.
func (s *Session) View(id string) (*View, error) {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()
	for _, view := range s.views {
		if view.ID() == id {
			return view, nil
		}
	}
	return nil, fmt.Errorf("no view with ID %q", id)
}

// SnapshotOf returns a Snapshot corresponding to the given URI.
//
// In the case where the file can be  can be associated with a View by
// [RelevantViews] (based on directory information alone, without package
// metadata), SnapshotOf returns the current Snapshot for that View. Otherwise,
// it awaits loading package metadata and returns a Snapshot for the first View
// containing a real (=not command-line-arguments) package for the file.
//
// If that also fails to find a View, SnapshotOf returns a Snapshot for the
// first view in s.views that is not shut down (i.e. s.views[0] unless we lose
// a race), for determinism in tests and so that we tend to aggregate the
// resulting command-line-arguments packages into a single view.
//
// SnapshotOf returns an error if a failure occurs along the way (most likely due
// to context cancellation), or if there are no Views in the Session.
//
// On success, the caller must call the returned function to release the snapshot.
func (s *Session) SnapshotOf(ctx context.Context, uri protocol.DocumentURI) (*Snapshot, func(), error) {
	uri = uri.Clean()
	// Fast path: if the uri has a static association with a view, return it.
	s.viewMu.Lock()
	v, err := s.viewOfLocked(ctx, uri)
	s.viewMu.Unlock()

	if err != nil {
		return nil, nil, err
	}

	if v != nil {
		snapshot, release, err := v.Snapshot()
		if err == nil {
			return snapshot, release, nil
		}
		// View is shut down. Forget this association.
		s.viewMu.Lock()
		if s.viewMap[uri] == v {
			delete(s.viewMap, uri)
		}
		s.viewMu.Unlock()
	}

	// Fall-back: none of the views could be associated with uri based on
	// directory information alone.
	//
	// Don't memoize the view association in viewMap, as it is not static: Views
	// may change as metadata changes.
	//
	// TODO(rfindley): we could perhaps optimize this case by peeking at existing
	// metadata before awaiting the load (after all, a load only adds metadata).
	// But that seems potentially tricky, when in the common case no loading
	// should be required.
	views := s.Views()
	for _, v := range views {
		snapshot, release, err := v.Snapshot()
		if err != nil {
			continue // view was shut down
		}
		// We don't check the error from awaitLoaded, because a load failure (that
		// doesn't result from context cancellation) should not prevent us from
		// continuing to search for the best view.
		_ = snapshot.awaitLoaded(ctx)
		g := snapshot.MetadataGraph()
		if ctx.Err() != nil {
			release()
			return nil, nil, ctx.Err()
		}
		// Special handling for the builtin file, since it doesn't have packages.
		if snapshot.IsBuiltin(uri) {
			return snapshot, release, nil
		}
		// Only match this view if it loaded a real package for the file.
		//
		// Any view can load a command-line-arguments package; aggregate those into
		// views[0] below.
		for _, pkg := range g.ForFile[uri] {
			if !metadata.IsCommandLineArguments(pkg.ID) || pkg.Standalone {
				return snapshot, release, nil
			}
		}
		release()
	}

	for _, v := range views {
		snapshot, release, err := v.Snapshot()
		if err == nil {
			return snapshot, release, nil // first valid snapshot
		}
	}
	return nil, nil, errNoViews
}

// FileOf returns the file for a given URI and its snapshot.
// On success, the returned function must be called to release the snapshot.
func (s *Session) FileOf(ctx context.Context, uri protocol.DocumentURI) (file.Handle, *Snapshot, func(), error) {
	snapshot, release, err := s.SnapshotOf(ctx, uri)
	if err != nil {
		return nil, nil, nil, err
	}
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		release()
		return nil, nil, nil, err
	}
	return fh, snapshot, release, nil
}

// errNoViews is sought by orphaned file diagnostics, to detect the case where
// we have no view containing a file.
var errNoViews = errors.New("no views")

// viewOfLocked evaluates the best view for uri, memoizing its result in
// s.viewMap.
//
// Precondition: caller holds s.viewMu lock; uri must be clean.
//
// May return (nil, nil) if no best view can be determined.
func (s *Session) viewOfLocked(ctx context.Context, uri protocol.DocumentURI) (*View, error) {
	if s.viewMap == nil {
		return nil, errors.New("session is shut down")
	}
	v, hit := s.viewMap[uri]
	if !hit {
		// Cache miss: compute (and memoize) the best view.
		fh, err := s.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		relevantViews, err := RelevantViews(ctx, s, fh.URI(), s.views)
		if err != nil {
			return nil, err
		}
		v = matchingView(fh, relevantViews)
		if v == nil && len(relevantViews) > 0 {
			// If we have relevant views, but none of them matched the file's build
			// constraints, then we are still better off using one of them here.
			// Otherwise, logic may fall back to an inferior view, which lacks
			// relevant module information, leading to misleading diagnostics.
			// (as in golang/go#60776).
			v = relevantViews[0]
		}
		s.viewMap[uri] = v // may be nil
	}
	return v, nil
}

func (s *Session) Views() []*View {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()
	result := make([]*View, len(s.views))
	copy(result, s.views)
	return result
}

// selectViewDefs constructs the best set of views covering the provided workspace
// folders and open files.
//
// This implements the zero-config algorithm of golang/go#57979.
func selectViewDefs(ctx context.Context, fs file.Source, folders []*Folder, openFiles []protocol.DocumentURI) ([]*viewDefinition, error) {
	var defs []*viewDefinition

	// First, compute a default view for each workspace folder.
	// TODO(golang/go#57979): technically, this is path dependent, since
	// DidChangeWorkspaceFolders could introduce a path-dependent ordering on
	// folders. We should keep folders sorted, or sort them here.
	for _, folder := range folders {
		def, err := defineView(ctx, fs, folder, nil)
		if err != nil {
			return nil, err
		}
		defs = append(defs, def)
	}

	// Next, ensure that the set of views covers all open files contained in a
	// workspace folder.
	//
	// We only do this for files contained in a workspace folder, because other
	// open files are most likely the result of jumping to a definition from a
	// workspace file; we don't want to create additional views in those cases:
	// they should be resolved after initialization.

	folderForFile := func(uri protocol.DocumentURI) *Folder {
		var longest *Folder
		for _, folder := range folders {
			// Check that this is a better match than longest, but not through a
			// vendor directory. Count occurrences of "/vendor/" as a quick check
			// that the vendor directory is between the folder and the file. Note the
			// addition of a trailing "/" to handle the odd case where the folder is named
			// vendor (which I hope is exceedingly rare in any case).
			//
			// Vendored packages are, by definition, part of an existing view.
			if (longest == nil || len(folder.Dir) > len(longest.Dir)) &&
				folder.Dir.Encloses(uri) &&
				strings.Count(string(uri), "/vendor/") == strings.Count(string(folder.Dir)+"/", "/vendor/") {

				longest = folder
			}
		}
		return longest
	}

checkFiles:
	for _, uri := range openFiles {
		folder := folderForFile(uri)
		if folder == nil || !folder.Options.ZeroConfig {
			continue // only guess views for open files
		}
		fh, err := fs.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		relevantViews, err := RelevantViews(ctx, fs, fh.URI(), defs)
		if err != nil {
			// We should never call selectViewDefs with a cancellable context, so
			// this should never fail.
			return nil, bug.Errorf("failed to find best view for open file: %v", err)
		}
		def := matchingView(fh, relevantViews)
		if def != nil {
			continue // file covered by an existing view
		}
		def, err = defineView(ctx, fs, folder, fh)
		if err != nil {
			// e.g. folder path is invalid?
			return nil, fmt.Errorf("failed to define view for open file: %v", err)
		}
		// It need not strictly be the case that the best view for a file is
		// distinct from other views, as the logic of getViewDefinition and
		// [RelevantViews] does not align perfectly. This is not necessarily a bug:
		// there may be files for which we can't construct a valid view.
		//
		// Nevertheless, we should not create redundant views.
		for _, alt := range defs {
			if viewDefinitionsEqual(alt, def) {
				continue checkFiles
			}
		}
		defs = append(defs, def)
	}

	return defs, nil
}

// The viewDefiner interface allows the [RelevantViews] algorithm to operate on both
// Views and viewDefinitions.
type viewDefiner interface{ definition() *viewDefinition }

// RelevantViews returns the views that may contain the given URI, or nil if
// none exist. A view is "relevant" if, ignoring build constraints, it may have
// a workspace package containing uri. Therefore, the definition of relevance
// depends on the view type.
func RelevantViews[V viewDefiner](ctx context.Context, fs file.Source, uri protocol.DocumentURI, views []V) ([]V, error) {
	if len(views) == 0 {
		return nil, nil // avoid the call to findRootPattern
	}
	dir := uri.Dir()
	modURI, err := findRootPattern(ctx, dir, "go.mod", fs)
	if err != nil {
		return nil, err
	}

	// Prefer GoWork > GoMod > GOPATH > GoPackages > AdHoc.
	var (
		goPackagesViews []V // prefer longest
		workViews       []V // prefer longest
		modViews        []V // exact match
		gopathViews     []V // prefer longest
		adHocViews      []V // exact match
	)

	// pushView updates the views slice with the matching view v, using the
	// heuristic that views with a longer root are preferable. Accordingly,
	// pushView may be a no op if v's root is shorter than the roots in the views
	// slice.
	//
	// Invariant: the length of all roots in views is the same.
	pushView := func(views *[]V, v V) {
		if len(*views) == 0 {
			*views = []V{v}
			return
		}
		better := func(l, r V) bool {
			return len(l.definition().root) > len(r.definition().root)
		}
		existing := (*views)[0]
		switch {
		case better(existing, v):
		case better(v, existing):
			*views = []V{v}
		default:
			*views = append(*views, v)
		}
	}

	for _, view := range views {
		switch def := view.definition(); def.Type() {
		case GoPackagesDriverView:
			if def.root.Encloses(dir) {
				pushView(&goPackagesViews, view)
			}
		case GoWorkView:
			if _, ok := def.workspaceModFiles[modURI]; ok || uri == def.gowork {
				pushView(&workViews, view)
			}
		case GoModView:
			if _, ok := def.workspaceModFiles[modURI]; ok {
				modViews = append(modViews, view)
			}
		case GOPATHView:
			if def.root.Encloses(dir) {
				pushView(&gopathViews, view)
			}
		case AdHocView:
			if def.root == dir {
				adHocViews = append(adHocViews, view)
			}
		}
	}

	// Now that we've collected matching views, choose the best match,
	// considering ports.
	//
	// We only consider one type of view, since the matching view created by
	// defineView should be of the best type.
	var relevantViews []V
	switch {
	case len(workViews) > 0:
		relevantViews = workViews
	case len(modViews) > 0:
		relevantViews = modViews
	case len(gopathViews) > 0:
		relevantViews = gopathViews
	case len(goPackagesViews) > 0:
		relevantViews = goPackagesViews
	case len(adHocViews) > 0:
		relevantViews = adHocViews
	}

	return relevantViews, nil
}

// matchingView returns the View or viewDefinition out of relevantViews that
// matches the given file's build constraints, or nil if no match is found.
//
// Making this function generic is convenient so that we can avoid mapping view
// definitions back to views inside Session.DidModifyFiles, where performance
// matters. It is, however, not the cleanest application of generics.
//
// Note: keep this function in sync with defineView.
func matchingView[V viewDefiner](fh file.Handle, relevantViews []V) V {
	var zero V

	if len(relevantViews) == 0 {
		return zero
	}

	content, err := fh.Content()

	// Port matching doesn't apply to non-go files, or files that no longer exist.
	// Note that the behavior here on non-existent files shouldn't matter much,
	// since there will be a subsequent failure.
	if fileKind(fh) != file.Go || err != nil {
		return relevantViews[0]
	}

	// Find the first view that matches constraints.
	// Content trimming is nontrivial, so do this outside of the loop below.
	path := fh.URI().Path()
	content = trimContentForPortMatch(content)
	for _, v := range relevantViews {
		def := v.definition()
		viewPort := port{def.GOOS(), def.GOARCH()}
		if viewPort.matches(path, content) {
			return v
		}
	}

	return zero // no view found
}

// ResetView resets the best view for the given URI.
func (s *Session) ResetView(ctx context.Context, uri protocol.DocumentURI) (*View, error) {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	if s.viewMap == nil {
		return nil, fmt.Errorf("session is shut down")
	}

	view, err := s.viewOfLocked(ctx, uri.Clean())
	if err != nil {
		return nil, err
	}
	if view == nil {
		return nil, fmt.Errorf("no view for %s", uri)
	}

	s.viewMap = make(map[protocol.DocumentURI]*View)
	for i, v := range s.views {
		if v == view {
			v2, _, release := s.createView(ctx, view.viewDefinition)
			release() // don't need the snapshot
			v.shutdown()
			s.views[i] = v2
			return v2, nil
		}
	}

	return nil, bug.Errorf("missing view") // can't happen...
}

// DidModifyFiles reports a file modification to the session. It returns
// the new snapshots after the modifications have been applied, paired with
// the affected file URIs for those snapshots.
// On success, it returns a release function that
// must be called when the snapshots are no longer needed.
//
// TODO(rfindley): what happens if this function fails? It must leave us in a
// broken state, which we should surface to the user, probably as a request to
// restart gopls.
func (s *Session) DidModifyFiles(ctx context.Context, modifications []file.Modification) (map[*View][]protocol.DocumentURI, error) {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	// Short circuit the logic below if s is shut down.
	if s.viewMap == nil {
		return nil, fmt.Errorf("session is shut down")
	}

	// Update overlays.
	//
	// This is done while holding viewMu because the set of open files affects
	// the set of views, and to prevent views from seeing updated file content
	// before they have processed invalidations.
	replaced, err := s.updateOverlays(ctx, modifications)
	if err != nil {
		return nil, err
	}

	// checkViews controls whether the set of views needs to be recomputed, for
	// example because a go.mod file was created or deleted, or a go.work file
	// changed on disk.
	checkViews := false

	// Hack: collect folders from existing views.
	// TODO(golang/go#57979): we really should track folders independent of
	// Views, but since we always have a default View for each folder, this
	// works for now.
	var folders []*Folder // preserve folder order
	workspaceFileGlobsSet := make(map[string]bool)
	seen := make(map[*Folder]unit)
	for _, v := range s.views {
		if _, ok := seen[v.folder]; ok {
			continue
		}
		seen[v.folder] = unit{}
		folders = append(folders, v.folder)
		for _, glob := range v.folder.Options.WorkspaceFiles {
			workspaceFileGlobsSet[glob] = true
		}
	}
	workspaceFileGlobs := slices.Collect(maps.Keys(workspaceFileGlobsSet))

	changed := make(map[protocol.DocumentURI]file.Handle)
	for _, c := range modifications {
		fh := mustReadFile(ctx, s, c.URI)
		changed[c.URI] = fh

		// Any change to the set of open files causes views to be recomputed.
		if c.Action == file.Open || c.Action == file.Close {
			checkViews = true
		}

		// Any on-disk change to a go.work or go.mod file causes recomputing views.
		//
		// TODO(rfindley): go.work files need not be named "go.work" -- we need to
		// check each view's source to handle the case of an explicit GOWORK value.
		// Write a test that fails, and fix this.
		if (isGoWork(c.URI) || isGoMod(c.URI) || isWorkspaceFile(c.URI, workspaceFileGlobs)) && (c.Action == file.Save || c.OnDisk) {
			checkViews = true
		}

		// Any change to the set of supported ports in a file may affect view
		// selection. This is perhaps more subtle than it first seems: since the
		// algorithm for selecting views considers open files in a deterministic
		// order, a change in supported ports may cause a different port to be
		// chosen, even if all open files still match an existing View!
		//
		// We endeavor to avoid that sort of path dependence, so must re-run the
		// view selection algorithm whenever any input changes.
		//
		// However, extracting the build comment is nontrivial, so we don't want to
		// pay this cost when e.g. processing a bunch of on-disk changes due to a
		// branch change. Be careful to only do this if both files are open Go
		// files.
		if old, ok := replaced[c.URI]; ok && !checkViews && fileKind(fh) == file.Go {
			if new, ok := fh.(*overlay); ok {
				if buildComment(old.content) != buildComment(new.content) {
					checkViews = true
				}
			}
		}
	}

	if checkViews {
		var openFiles []protocol.DocumentURI
		for _, o := range s.Overlays() {
			openFiles = append(openFiles, o.URI())
		}
		// Sort for determinism.
		slices.Sort(openFiles)

		// TODO(rfindley): can we avoid running the go command (go env)
		// synchronously to change processing? Can we assume that the env did not
		// change, and derive go.work using a combination of the configured
		// GOWORK value and filesystem?
		defs, err := selectViewDefs(ctx, s, folders, openFiles)
		if err != nil {
			// Catastrophic failure, equivalent to a failure of session
			// initialization and therefore should almost never happen. One
			// scenario where this failure mode could occur is if some file
			// permissions have changed preventing us from reading go.mod
			// files.
			//
			// TODO(rfindley): consider surfacing this error more loudly. We
			// could report a bug, but it's not really a bug.
			event.Error(ctx, "selecting new views", err)
		} else {
			kept := make(map[*View]unit)
			var newViews []*View
			for _, def := range defs {
				var newView *View
				// Reuse existing view?
				for _, v := range s.views {
					if viewDefinitionsEqual(def, v.viewDefinition) {
						newView = v
						kept[v] = unit{}
						break
					}
				}
				if newView == nil {
					v, _, release := s.createView(ctx, def)
					release()
					newView = v
				}
				newViews = append(newViews, newView)
			}
			for _, v := range s.views {
				if _, ok := kept[v]; !ok {
					v.shutdown()
				}
			}
			s.views = newViews
			s.viewMap = make(map[protocol.DocumentURI]*View)
		}
	}

	// We only want to run fast-path diagnostics (i.e. diagnoseChangedFiles) once
	// for each changed file, in its best view.
	viewsToDiagnose := map[*View][]protocol.DocumentURI{}
	for _, mod := range modifications {
		v, err := s.viewOfLocked(ctx, mod.URI)
		if err != nil {
			// viewOfLocked only returns an error in the event of context
			// cancellation, or if the session is shut down. Since state changes
			// should occur on an uncancellable context, and s.viewMap was checked at
			// the top of this function, an error here is a bug.
			bug.Reportf("finding best view for change: %v", err)
			continue
		}
		if v != nil {
			viewsToDiagnose[v] = append(viewsToDiagnose[v], mod.URI)
		}
	}

	// ...but changes may be relevant to other views, for example if they are
	// changes to a shared package.
	for _, v := range s.views {
		_, release, needsDiagnosis := s.invalidateViewLocked(ctx, v, StateChange{Modifications: modifications, Files: changed})
		release()

		if needsDiagnosis || checkViews {
			if _, ok := viewsToDiagnose[v]; !ok {
				viewsToDiagnose[v] = nil
			}
		}
	}

	return viewsToDiagnose, nil
}

// ExpandModificationsToDirectories returns the set of changes with the
// directory changes removed and expanded to include all of the files in
// the directory.
func (s *Session) ExpandModificationsToDirectories(ctx context.Context, changes []file.Modification) []file.Modification {
	var snapshots []*Snapshot
	s.viewMu.Lock()
	for _, v := range s.views {
		snapshot, release, err := v.Snapshot()
		if err != nil {
			continue // view is shut down; continue with others
		}
		defer release()
		snapshots = append(snapshots, snapshot)
	}
	s.viewMu.Unlock()

	// Expand the modification to any file we could care about, which we define
	// to be any file observed by any of the snapshots.
	//
	// There may be other files in the directory, but if we haven't read them yet
	// we don't need to invalidate them.
	var result []file.Modification
	for _, c := range changes {
		expanded := make(map[protocol.DocumentURI]bool)
		for _, snapshot := range snapshots {
			for _, uri := range snapshot.filesInDir(c.URI) {
				expanded[uri] = true
			}
		}
		if len(expanded) == 0 {
			result = append(result, c)
		} else {
			for uri := range expanded {
				result = append(result, file.Modification{
					URI:        uri,
					Action:     c.Action,
					LanguageID: "",
					OnDisk:     c.OnDisk,
					// changes to directories cannot include text or versions
				})
			}
		}
	}
	return result
}

// updateOverlays updates the set of overlays and returns a map of any existing
// overlay values that were replaced.
//
// Precondition: caller holds s.viewMu lock.
// TODO(rfindley): move this to fs_overlay.go.
func (fs *overlayFS) updateOverlays(ctx context.Context, changes []file.Modification) (map[protocol.DocumentURI]*overlay, error) {
	fs.mu.Lock()
	defer fs.mu.Unlock()

	replaced := make(map[protocol.DocumentURI]*overlay)
	for _, c := range changes {
		o, ok := fs.overlays[c.URI]
		if ok {
			replaced[c.URI] = o
		}

		// If the file is not opened in an overlay and the change is on disk,
		// there's no need to update an overlay. If there is an overlay, we
		// may need to update the overlay's saved value.
		if !ok && c.OnDisk {
			continue
		}

		// Determine the file kind on open, otherwise, assume it has been cached.
		var kind file.Kind
		switch c.Action {
		case file.Open:
			kind = file.KindForLang(c.LanguageID)
		default:
			if !ok {
				return nil, fmt.Errorf("updateOverlays: modifying unopened overlay %v", c.URI)
			}
			kind = o.kind
		}

		// Closing a file just deletes its overlay.
		if c.Action == file.Close {
			delete(fs.overlays, c.URI)
			continue
		}

		// If the file is on disk, check if its content is the same as in the
		// overlay. Saves and on-disk file changes don't come with the file's
		// content.
		text := c.Text
		if text == nil && (c.Action == file.Save || c.OnDisk) {
			if !ok {
				return nil, fmt.Errorf("no known content for overlay for %s", c.Action)
			}
			text = o.content
		}
		// On-disk changes don't come with versions.
		version := c.Version
		if c.OnDisk || c.Action == file.Save {
			version = o.version
		}
		hash := file.HashOf(text)
		var sameContentOnDisk bool
		switch c.Action {
		case file.Delete:
			// Do nothing. sameContentOnDisk should be false.
		case file.Save:
			// Make sure the version and content (if present) is the same.
			if false && o.version != version { // Client no longer sends the version
				return nil, fmt.Errorf("updateOverlays: saving %s at version %v, currently at %v", c.URI, c.Version, o.version)
			}
			if c.Text != nil && o.hash != hash {
				return nil, fmt.Errorf("updateOverlays: overlay %s changed on save", c.URI)
			}
			sameContentOnDisk = true
		default:
			fh := mustReadFile(ctx, fs.delegate, c.URI)
			_, readErr := fh.Content()
			sameContentOnDisk = (readErr == nil && fh.Identity().Hash == hash)
		}
		o = &overlay{
			uri:     c.URI,
			version: version,
			content: text,
			modTime: time.Now(),
			kind:    kind,
			hash:    hash,
			saved:   sameContentOnDisk,
		}

		// NOTE: previous versions of this code checked here that the overlay had a
		// view and file kind (but we don't know why).

		fs.overlays[c.URI] = o
	}

	return replaced, nil
}

func mustReadFile(ctx context.Context, fs file.Source, uri protocol.DocumentURI) file.Handle {
	ctx = xcontext.Detach(ctx)
	fh, err := fs.ReadFile(ctx, uri)
	if err != nil {
		// ReadFile cannot fail with an uncancellable context.
		bug.Reportf("reading file failed unexpectedly: %v", err)
		return brokenFile{uri, err}
	}
	return fh
}

// A brokenFile represents an unexpected failure to read a file.
type brokenFile struct {
	uri protocol.DocumentURI
	err error
}

func (b brokenFile) String() string              { return b.uri.Path() }
func (b brokenFile) URI() protocol.DocumentURI   { return b.uri }
func (b brokenFile) Identity() file.Identity     { return file.Identity{URI: b.uri} }
func (b brokenFile) SameContentsOnDisk() bool    { return false }
func (b brokenFile) Version() int32              { return 0 }
func (b brokenFile) Content() ([]byte, error)    { return nil, b.err }
func (b brokenFile) ModTime() (time.Time, error) { return time.Time{}, b.err }

// FileWatchingGlobPatterns returns a set of glob patterns that the client is
// required to watch for changes, and notify the server of them, in order to
// keep the server's state up to date.
//
// This set includes
//  1. all go.mod and go.work files in the workspace; and
//  2. all files defined by the WorkspaceFiles option in BuildOptions (to support custom GOPACKAGESDRIVERS); and
//  3. for each Snapshot, its modules (or directory for ad-hoc views). In
//     module mode, this is the set of active modules (and for VS Code, all
//     workspace directories within them, due to golang/go#42348).
//
// The watch for workspace files in (1) is sufficient to
// capture changes to the repo structure that may affect the set of views.
// Whenever this set changes, we reload the workspace and invalidate memoized
// files.
//
// The watch for workspace directories in (2) should keep each View up to date,
// as it should capture any newly added/modified/deleted Go files.
//
// Patterns are returned as a set of protocol.RelativePatterns, since they can
// always be later translated to glob patterns (i.e. strings) if the client
// lacks relative pattern support. By convention, any pattern returned with
// empty baseURI should be served as a glob pattern.
//
// In general, we prefer to serve relative patterns, as they work better on
// most clients that support both, and do not have issues with Windows driver
// letter casing:
// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#relativePattern
//
// TODO(golang/go#57979): we need to reset the memoizedFS when a view changes.
// Consider the case where we incidentally read a file, then it moved outside
// of an active module, and subsequently changed: we would still observe the
// original file state.
func (s *Session) FileWatchingGlobPatterns(ctx context.Context) map[protocol.RelativePattern]unit {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	// Always watch files that may change the set of views.
	patterns := map[protocol.RelativePattern]unit{
		{Pattern: "**/*.{mod,work}"}: {},
	}

	for _, view := range s.views {
		snapshot, release, err := view.Snapshot()
		if err != nil {
			continue // view is shut down; continue with others
		}
		maps.Copy(patterns, snapshot.fileWatchingGlobPatterns())
		release()
	}
	return patterns
}

// OrphanedFileDiagnostics reports diagnostics describing why open files have
// no packages or have only command-line-arguments packages.
//
// If the resulting diagnostic is nil, the file is either not orphaned or we
// can't produce a good diagnostic.
//
// The caller must not mutate the result.
func (s *Session) OrphanedFileDiagnostics(ctx context.Context) (map[protocol.DocumentURI][]*Diagnostic, error) {
	if err := ctx.Err(); err != nil {
		// Avoid collecting diagnostics if the context is cancelled.
		// (Previously, it was possible to get all the way to packages.Load on a cancelled context)
		return nil, err
	}
	// Note: diagnostics holds a slice for consistency with other diagnostic
	// funcs.
	diagnostics := make(map[protocol.DocumentURI][]*Diagnostic)

	byView := make(map[*View][]*overlay)
	for _, o := range s.Overlays() {
		uri := o.URI()
		snapshot, release, err := s.SnapshotOf(ctx, uri)
		if err != nil {
			// TODO(golang/go#57979): we have to use the .go suffix as an approximation for
			// file kind here, because we don't have access to Options if no View was
			// matched.
			//
			// But Options are really a property of Folder, not View, and we could
			// match a folder here.
			//
			// Refactor so that Folders are tracked independently of Views, and use
			// the correct options here to get the most accurate file kind.
			//
			// TODO(golang/go#57979): once we switch entirely to the zeroconfig
			// logic, we should use this diagnostic for the fallback case of
			// s.views[0] in the ViewOf logic.
			if errors.Is(err, errNoViews) {
				if strings.HasSuffix(string(uri), ".go") {
					if _, rng, ok := orphanedFileDiagnosticRange(ctx, s.parseCache, o); ok {
						diagnostics[uri] = []*Diagnostic{{
							URI:      uri,
							Range:    rng,
							Severity: protocol.SeverityWarning,
							Source:   ListError,
							Message:  fmt.Sprintf("No active builds contain %s: consider opening a new workspace folder containing it", uri.Path()),
						}}
					}
				}
				continue
			}
			return nil, err
		}
		v := snapshot.View()
		release()
		byView[v] = append(byView[v], o)
	}

	for view, overlays := range byView {
		snapshot, release, err := view.Snapshot()
		if err != nil {
			continue // view is shutting down
		}
		defer release()
		diags, err := snapshot.orphanedFileDiagnostics(ctx, overlays)
		if err != nil {
			return nil, err
		}
		for _, d := range diags {
			diagnostics[d.URI] = append(diagnostics[d.URI], d)
		}
	}
	return diagnostics, nil
}


================================================
FILE: gopls/internal/cache/session_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"os"
	"path"
	"path/filepath"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/testenv"
)

func TestZeroConfigAlgorithm(t *testing.T) {
	testenv.NeedsExec(t) // executes the Go command
	t.Setenv("GOPACKAGESDRIVER", "off")

	type viewSummary struct {
		// fields exported for cmp.Diff
		Type ViewType
		Root string
		Env  []string
	}

	type folderSummary struct {
		dir     string
		options func(dir string) map[string]any // options may refer to the temp dir
	}

	includeReplaceInWorkspace := func(string) map[string]any {
		return map[string]any{
			"includeReplaceInWorkspace": true,
		}
	}

	type test struct {
		name    string
		files   map[string]string // use a map rather than txtar as file content is tiny
		folders []folderSummary
		open    []string // open files
		want    []viewSummary
	}

	tests := []test{
		// TODO(rfindley): add a test for GOPACKAGESDRIVER.
		// Doing so doesn't yet work using options alone (user env is not honored)

		// TODO(rfindley): add a test for degenerate cases, such as missing
		// workspace folders (once we decide on the correct behavior).
		{
			"basic go.work workspace",
			map[string]string{
				"go.work":  "go 1.18\nuse (\n\t./a\n\t./b\n)\n",
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
			},
			[]folderSummary{{dir: "."}},
			nil,
			[]viewSummary{{GoWorkView, ".", nil}},
		},
		{
			"basic go.mod workspace",
			map[string]string{
				"go.mod": "module golang.org/a\ngo 1.18\n",
			},
			[]folderSummary{{dir: "."}},
			nil,
			[]viewSummary{{GoModView, ".", nil}},
		},
		{
			"basic GOPATH workspace",
			map[string]string{
				"src/golang.org/a/a.go": "package a",
				"src/golang.org/b/b.go": "package b",
			},
			[]folderSummary{{
				dir: "src",
				options: func(dir string) map[string]any {
					return map[string]any{
						"env": map[string]any{
							"GO111MODULE": "", // golang/go#70196: must be unset
							"GOPATH":      dir,
						},
					}
				},
			}},
			[]string{"src/golang.org/a//a.go", "src/golang.org/b/b.go"},
			[]viewSummary{{GOPATHView, "src", nil}},
		},
		{
			"basic AdHoc workspace",
			map[string]string{
				"foo.go": "package foo",
			},
			[]folderSummary{{dir: "."}},
			nil,
			[]viewSummary{{AdHocView, ".", nil}},
		},
		{
			"multi-folder workspace",
			map[string]string{
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
			},
			[]folderSummary{{dir: "a"}, {dir: "b"}},
			nil,
			[]viewSummary{{GoModView, "a", nil}, {GoModView, "b", nil}},
		},
		{
			"multi-module workspace",
			map[string]string{
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
			},
			[]folderSummary{{dir: "."}},
			nil,
			[]viewSummary{{AdHocView, ".", nil}},
		},
		{
			"zero-config open module",
			map[string]string{
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"a/a.go":   "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go"},
			[]viewSummary{
				{AdHocView, ".", nil},
				{GoModView, "a", nil},
			},
		},
		{
			"zero-config open modules",
			map[string]string{
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"a/a.go":   "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{
				{AdHocView, ".", nil},
				{GoModView, "a", nil},
				{GoModView, "b", nil},
			},
		},
		{
			"unified workspace",
			map[string]string{
				"go.work":  "go 1.18\nuse (\n\t./a\n\t./b\n)\n",
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"a/a.go":   "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{{GoWorkView, ".", nil}},
		},
		{
			"go.work from env",
			map[string]string{
				"nested/go.work": "go 1.18\nuse (\n\t../a\n\t../b\n)\n",
				"a/go.mod":       "module golang.org/a\ngo 1.18\n",
				"a/a.go":         "package a",
				"b/go.mod":       "module golang.org/b\ngo 1.18\n",
				"b/b.go":         "package b",
			},
			[]folderSummary{{
				dir: ".",
				options: func(dir string) map[string]any {
					return map[string]any{
						"env": map[string]any{
							"GOWORK": filepath.Join(dir, "nested", "go.work"),
						},
					}
				},
			}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{{GoWorkView, ".", nil}},
		},
		{
			"independent module view",
			map[string]string{
				"go.work":  "go 1.18\nuse (\n\t./a\n)\n", // not using b
				"a/go.mod": "module golang.org/a\ngo 1.18\n",
				"a/a.go":   "package a",
				"b/go.mod": "module golang.org/a\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{
				{GoWorkView, ".", nil},
				{GoModView, "b", []string{"GOWORK=off"}},
			},
		},
		{
			"multiple go.work",
			map[string]string{
				"go.work":    "go 1.18\nuse (\n\t./a\n\t./b\n)\n",
				"a/go.mod":   "module golang.org/a\ngo 1.18\n",
				"a/a.go":     "package a",
				"b/go.work":  "go 1.18\nuse (\n\t.\n\t./c\n)\n",
				"b/go.mod":   "module golang.org/b\ngo 1.18\n",
				"b/b.go":     "package b",
				"b/c/go.mod": "module golang.org/c\ngo 1.18\n",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go", "b/b.go", "b/c/c.go"},
			[]viewSummary{{GoWorkView, ".", nil}, {GoWorkView, "b", nil}},
		},
		{
			"multiple go.work, c unused",
			map[string]string{
				"go.work":    "go 1.18\nuse (\n\t./a\n\t./b\n)\n",
				"a/go.mod":   "module golang.org/a\ngo 1.18\n",
				"a/a.go":     "package a",
				"b/go.work":  "go 1.18\nuse (\n\t.\n)\n",
				"b/go.mod":   "module golang.org/b\ngo 1.18\n",
				"b/b.go":     "package b",
				"b/c/go.mod": "module golang.org/c\ngo 1.18\n",
			},
			[]folderSummary{{dir: "."}},
			[]string{"a/a.go", "b/b.go", "b/c/c.go"},
			[]viewSummary{{GoWorkView, ".", nil}, {GoModView, "b/c", []string{"GOWORK=off"}}},
		},
		{
			"go.mod with nested replace",
			map[string]string{
				"go.mod":   "module golang.org/a\n require golang.org/b v1.2.3\nreplace example.com/b => ./b",
				"a.go":     "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: ".", options: includeReplaceInWorkspace}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{{GoModView, ".", nil}},
		},
		{
			"go.mod with parent replace, parent folder",
			map[string]string{
				"go.mod":   "module golang.org/a",
				"a.go":     "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\nrequire golang.org/a v1.2.3\nreplace golang.org/a => ../",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: ".", options: includeReplaceInWorkspace}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{{GoModView, ".", nil}, {GoModView, "b", nil}},
		},
		{
			"go.mod with multiple replace",
			map[string]string{
				"go.mod": `
module golang.org/root

require (
	golang.org/a v1.2.3
	golang.org/b v1.2.3
	golang.org/c v1.2.3
)

replace (
	golang.org/b => ./b
	golang.org/c => ./c
	// Note: d is not replaced
)
`,
				"a.go":     "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18",
				"b/b.go":   "package b",
				"c/go.mod": "module golang.org/c\ngo 1.18",
				"c/c.go":   "package c",
				"d/go.mod": "module golang.org/d\ngo 1.18",
				"d/d.go":   "package d",
			},
			[]folderSummary{{dir: ".", options: includeReplaceInWorkspace}},
			[]string{"b/b.go", "c/c.go", "d/d.go"},
			[]viewSummary{{GoModView, ".", nil}, {GoModView, "d", nil}},
		},
		{
			"go.mod with replace outside the workspace",
			map[string]string{
				"go.mod":   "module golang.org/a\ngo 1.18",
				"a.go":     "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\nrequire golang.org/a v1.2.3\nreplace golang.org/a => ../",
				"b/b.go":   "package b",
			},
			[]folderSummary{{dir: "b"}},
			[]string{"a.go", "b/b.go"},
			[]viewSummary{{GoModView, "b", nil}},
		},
		{
			"go.mod with replace directive; workspace replace off",
			map[string]string{
				"go.mod":   "module golang.org/a\n require golang.org/b v1.2.3\nreplace example.com/b => ./b",
				"a.go":     "package a",
				"b/go.mod": "module golang.org/b\ngo 1.18\n",
				"b/b.go":   "package b",
			},
			[]folderSummary{{
				dir: ".",
				options: func(string) map[string]any {
					return map[string]any{
						"includeReplaceInWorkspace": false,
					}
				},
			}},
			[]string{"a/a.go", "b/b.go"},
			[]viewSummary{{GoModView, ".", nil}, {GoModView, "b", nil}},
		},
	}

	for _, test := range tests {
		ctx := context.Background()
		t.Run(test.name, func(t *testing.T) {
			dir := writeFiles(t, test.files)
			rel := fake.RelativeTo(dir)
			fs := newMemoizedFS()

			toURI := func(path string) protocol.DocumentURI {
				return protocol.URIFromPath(rel.AbsPath(path))
			}

			var folders []*Folder
			for _, f := range test.folders {
				opts := settings.DefaultOptions()
				if f.options != nil {
					_, errs := opts.Set(f.options(dir))
					for _, err := range errs {
						t.Fatal(err)
					}
				}
				uri := toURI(f.dir)
				env, err := FetchGoEnv(ctx, uri, opts)
				if err != nil {
					t.Fatalf("FetchGoEnv failed: %v", err)
				}
				t.Logf("FetchGoEnv(%q) = %+v", uri, env)
				folders = append(folders, &Folder{
					Dir:     uri,
					Name:    path.Base(f.dir),
					Options: opts,
					Env:     *env,
				})
			}

			var openFiles []protocol.DocumentURI
			for _, path := range test.open {
				openFiles = append(openFiles, toURI(path))
			}

			defs, err := selectViewDefs(ctx, fs, folders, openFiles)
			if err != nil {
				t.Fatal(err)
			}
			var got []viewSummary
			for _, def := range defs {
				got = append(got, viewSummary{
					Type: def.Type(),
					Root: rel.RelPath(def.root.Path()),
					Env:  def.EnvOverlay(),
				})
			}
			if diff := cmp.Diff(test.want, got); diff != "" {
				t.Errorf("selectViews() mismatch (-want +got):\n%s", diff)
			}
		})
	}
}

// TODO(rfindley): this function could be meaningfully factored with the
// various other test helpers of this nature.
func writeFiles(t *testing.T, files map[string]string) string {
	root := t.TempDir()

	// This unfortunate step is required because gopls output
	// expands symbolic links in its input file names (arguably it
	// should not), and on macOS the temp dir is in /var -> private/var.
	root, err := filepath.EvalSymlinks(root)
	if err != nil {
		t.Fatal(err)
	}

	for name, content := range files {
		filename := filepath.Join(root, name)
		if err := os.MkdirAll(filepath.Dir(filename), 0777); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filename, []byte(content), 0666); err != nil {
			t.Fatal(err)
		}
	}
	return root
}


================================================
FILE: gopls/internal/cache/snapshot.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"bytes"
	"cmp"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/build/constraint"
	"go/parser"
	"go/token"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"slices"
	"strconv"
	"strings"
	"sync"

	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/methodsets"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/testfuncs"
	"golang.org/x/tools/gopls/internal/cache/xrefs"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/filecache"
	label1 "golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/constraints"
	"golang.org/x/tools/gopls/internal/util/immutable"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/pathutil"
	"golang.org/x/tools/gopls/internal/util/persistent"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/label"
	"golang.org/x/tools/internal/gocommand"
)

// A Snapshot represents the current state for a given view.
//
// It is first and foremost an idempotent implementation of file.Source whose
// ReadFile method returns consistent information about the existence and
// content of each file throughout its lifetime.
//
// However, the snapshot also manages additional state (such as parsed files
// and packages) that are derived from file content.
//
// Snapshots are responsible for bookkeeping and invalidation of this state,
// implemented in Snapshot.clone.
type Snapshot struct {
	// sequenceID is the monotonically increasing ID of this snapshot within its View.
	//
	// Sequence IDs for Snapshots from different Views cannot be compared.
	sequenceID uint64

	// TODO(rfindley): the snapshot holding a reference to the view poses
	// lifecycle problems: a view may be shut down and waiting for work
	// associated with this snapshot to complete. While most accesses of the view
	// are benign (options or workspace information), this is not formalized and
	// it is wrong for the snapshot to use a shutdown view.
	//
	// Fix this by passing options and workspace information to the snapshot,
	// both of which should be immutable for the snapshot.
	view *View

	cancel        func()
	backgroundCtx context.Context

	store *memoize.Store // cache of handles shared by all snapshots

	refMu sync.Mutex

	// refcount holds the number of outstanding references to the current
	// Snapshot. When refcount is decremented to 0, the Snapshot maps are
	// destroyed and the done function is called.
	//
	// TODO(rfindley): use atomic.Int32 on Go 1.19+.
	refcount int
	done     func() // for implementing Session.Shutdown

	// mu guards all of the maps in the snapshot, as well as the builtin URI and
	// initialized.
	mu sync.Mutex

	// initialized reports whether the snapshot has been initialized. Concurrent
	// initialization is guarded by the view.initializationSema. Each snapshot is
	// initialized at most once: concurrent initialization is guarded by
	// view.initializationSema.
	initialized bool

	// initialErr holds the last error resulting from initialization. If
	// initialization fails, we only retry when the workspace modules change,
	// to avoid too many go/packages calls.
	// If initialized is false, initialErr still holds the error resulting from
	// the previous initialization.
	// TODO(rfindley): can we unify the lifecycle of initialized and initialErr.
	initialErr *InitializationError

	// builtin is the location of builtin.go in GOROOT.
	//
	// TODO(rfindley): would it make more sense to eagerly parse builtin, and
	// instead store a *parsego.File here?
	builtin protocol.DocumentURI

	// meta holds loaded metadata.
	//
	// meta is guarded by mu, but the Graph itself is immutable.
	//
	// TODO(rfindley): in many places we hold mu while operating on meta, even
	// though we only need to hold mu while reading the pointer.
	meta *metadata.Graph

	// files maps file URIs to their corresponding FileHandles.
	// It may invalidated when a file's content changes.
	files *fileMap

	// packages maps a packageKey to a *packageHandle.
	// It may be invalidated when a file's content changes.
	//
	// Invariants to preserve:
	//  - packages.Get(id).meta == meta.metadata[id] for all ids
	//  - if a package is in packages, then all of its dependencies should also
	//    be in packages, unless there is a missing import
	packages *persistent.Map[PackageID, *packageHandle]

	// fullAnalysisKeys and factyAnalysisKeys hold memoized cache keys for
	// analysis packages. "full" refers to the cache key including all enabled
	// analyzers, whereas "facty" is the key including only the subset of enabled
	// analyzers that produce facts, such as is required for transitively
	// imported packages.
	//
	// These keys are memoized because they can be quite expensive to compute.
	fullAnalysisKeys  *persistent.Map[PackageID, file.Hash]
	factyAnalysisKeys *persistent.Map[PackageID, file.Hash]

	// workspacePackages contains the workspace's packages, which are loaded
	// when the view is created. It does not contain intermediate test variants.
	workspacePackages immutable.Map[PackageID, PackagePath]

	// shouldLoad tracks packages that need to be reloaded, mapping a PackageID
	// to the package paths that should be used to reload it
	//
	// When we try to load a package, we clear it from the shouldLoad map
	// regardless of whether the load succeeded, to prevent endless loads.
	shouldLoad *persistent.Map[PackageID, []PackagePath]

	// unloadableFiles keeps track of files that we've failed to load.
	unloadableFiles *persistent.Set[protocol.DocumentURI]

	// TODO(rfindley): rename the handles below to "promises". A promise is
	// different from a handle (we mutate the package handle.)

	// parseModHandles keeps track of any parseModHandles for the snapshot.
	// The handles need not refer to only the view's go.mod file.
	parseModHandles *persistent.Map[protocol.DocumentURI, *memoize.Promise] // *memoize.Promise[parseModResult]

	// parseWorkHandles keeps track of any parseWorkHandles for the snapshot.
	// The handles need not refer to only the view's go.work file.
	parseWorkHandles *persistent.Map[protocol.DocumentURI, *memoize.Promise] // *memoize.Promise[parseWorkResult]

	// Preserve go.mod-related handles to avoid garbage-collecting the results
	// of various calls to the go command. The handles need not refer to only
	// the view's go.mod file.
	modTidyHandles *persistent.Map[protocol.DocumentURI, *memoize.Promise] // *memoize.Promise[modTidyResult]
	modWhyHandles  *persistent.Map[protocol.DocumentURI, *memoize.Promise] // *memoize.Promise[modWhyResult]
	modVulnHandles *persistent.Map[protocol.DocumentURI, *memoize.Promise] // *memoize.Promise[modVulnResult]

	// moduleUpgrades tracks known upgrades for module paths in each modfile.
	// Each modfile has a map of module name to upgrade version.
	moduleUpgrades *persistent.Map[protocol.DocumentURI, map[string]string]

	// vulns maps each go.mod file's URI to its known vulnerabilities.
	vulns *persistent.Map[protocol.DocumentURI, *vulncheck.Result]

	// compilerOptDetails is the set of directories whose packages
	// and tests need compiler optimization details in the diagnostics.
	compilerOptDetails map[protocol.DocumentURI]unit

	// Concurrent type checking:
	// typeCheckMu guards the ongoing type checking batch, and reference count of
	// ongoing type checking operations.
	// When the batch is no longer needed (batchRef=0), it is discarded.
	typeCheckMu sync.Mutex
	batchRef    int
	batch       *typeCheckBatch
}

var _ memoize.RefCounted = (*Snapshot)(nil) // snapshots are reference-counted

func (s *Snapshot) awaitPromise(ctx context.Context, p *memoize.Promise) (any, error) {
	return p.Get(ctx, s)
}

// Acquire prevents the snapshot from being destroyed until the returned
// function is called.
//
// (s.Acquire().release() could instead be expressed as a pair of
// method calls s.IncRef(); s.DecRef(). The latter has the advantage
// that the DecRefs are fungible and don't require holding anything in
// addition to the refcounted object s, but paradoxically that is also
// an advantage of the current approach, which forces the caller to
// consider the release function at every stage, making a reference
// leak more obvious.)
func (s *Snapshot) Acquire() func() {
	s.refMu.Lock()
	defer s.refMu.Unlock()
	assert(s.refcount > 0, "non-positive refs")
	s.refcount++

	return s.decref
}

// decref should only be referenced by Acquire, and by View when it frees its
// reference to View.snapshot.
func (s *Snapshot) decref() {
	s.refMu.Lock()
	defer s.refMu.Unlock()

	assert(s.refcount > 0, "non-positive refs")
	s.refcount--
	if s.refcount == 0 {
		s.packages.Destroy()
		s.files.destroy()
		s.parseModHandles.Destroy()
		s.parseWorkHandles.Destroy()
		s.modTidyHandles.Destroy()
		s.modVulnHandles.Destroy()
		s.modWhyHandles.Destroy()
		s.unloadableFiles.Destroy()
		s.moduleUpgrades.Destroy()
		s.vulns.Destroy()
		s.done()
	}
}

// SequenceID is the sequence id of this snapshot within its containing
// view.
//
// Relative to their view sequence ids are monotonically increasing, but this
// does not hold globally: when new views are created their initial snapshot
// has sequence ID 0.
func (s *Snapshot) SequenceID() uint64 {
	return s.sequenceID
}

// Labels returns a new slice of labels that should be used for events
// related to a snapshot.
func (s *Snapshot) Labels() []label.Label {
	return []label.Label{
		label1.ViewID.Of(s.view.id),
		label1.Snapshot.Of(s.SequenceID()),
		label1.Directory.Of(s.Folder().Path()),
	}
}

// Folder returns the folder at the base of this snapshot.
func (s *Snapshot) Folder() protocol.DocumentURI {
	return s.view.folder.Dir
}

// View returns the View associated with this snapshot.
func (s *Snapshot) View() *View {
	return s.view
}

// FileKind returns the kind of a file.
//
// We can't reliably deduce the kind from the file name alone,
// as some editors can be told to interpret a buffer as
// language different from the file name heuristic, e.g. that
// an .html file actually contains Go "html/template" syntax,
// or even that a .go file contains Python.
func (s *Snapshot) FileKind(fh file.Handle) file.Kind {
	if k := fileKind(fh); k != file.UnknownKind {
		return k
	}
	fext := filepath.Ext(fh.URI().Path())
	exts := s.Options().TemplateExtensions
	for _, ext := range exts {
		if fext == ext || fext == "."+ext {
			return file.Tmpl
		}
	}

	// and now what? This should never happen, but it does for cgo before go1.15
	//
	// TODO(rfindley): this doesn't look right. We should default to UnknownKind.
	// Also, I don't understand the comment above, though I'd guess before go1.15
	// we encountered cgo files without the .go extension.
	return file.Go
}

// fileKind returns the default file kind for a file, before considering
// template file extensions. See [Snapshot.FileKind].
func fileKind(fh file.Handle) file.Kind {
	// The kind of an unsaved buffer comes from the
	// TextDocumentItem.LanguageID field in the didChange event,
	// not from the file name. They may differ.
	if o, ok := fh.(*overlay); ok {
		if o.kind != file.UnknownKind {
			return o.kind
		}
	}

	fext := filepath.Ext(fh.URI().Path())
	switch fext {
	case ".go":
		return file.Go
	case ".mod":
		return file.Mod
	case ".sum":
		return file.Sum
	case ".work":
		return file.Work
	case ".s":
		return file.Asm
	}
	return file.UnknownKind
}

// Options returns the options associated with this snapshot.
func (s *Snapshot) Options() *settings.Options {
	return s.view.folder.Options
}

// BackgroundContext returns a context used for all background processing
// on behalf of this snapshot.
func (s *Snapshot) BackgroundContext() context.Context {
	return s.backgroundCtx
}

// Templates returns the .tmpl files.
func (s *Snapshot) Templates() map[protocol.DocumentURI]file.Handle {
	s.mu.Lock()
	defer s.mu.Unlock()

	tmpls := map[protocol.DocumentURI]file.Handle{}
	for k, fh := range s.files.all() {
		if s.FileKind(fh) == file.Tmpl {
			tmpls[k] = fh
		}
	}
	return tmpls
}

// RunGoModUpdateCommands runs a series of `go` commands that updates the go.mod
// and go.sum file for wd, and returns their updated contents.
//
// TODO(rfindley): the signature of RunGoModUpdateCommands is very confusing,
// and is the only thing forcing the ModFlag and ModFile indirection.
// Simplify it.
func (s *Snapshot) RunGoModUpdateCommands(ctx context.Context, modURI protocol.DocumentURI, run func(invoke func(...string) (*bytes.Buffer, error)) error) ([]byte, []byte, error) {
	tempDir, cleanupModDir, err := TempModDir(ctx, s, modURI)
	if err != nil {
		return nil, nil, err
	}
	defer cleanupModDir()

	// TODO(rfindley): we must use ModFlag and ModFile here (rather than simply
	// setting Args), because without knowing the verb, we can't know whether
	// ModFlag is appropriate. Refactor so that args can be set by the caller.
	inv, cleanupInvocation, err := s.GoCommandInvocation(NetworkOK, modURI.DirPath(), "", nil, "GOWORK=off")
	if err != nil {
		return nil, nil, err
	}
	defer cleanupInvocation()

	inv.ModFlag = "mod"
	inv.ModFile = filepath.Join(tempDir, "go.mod")
	invoke := func(args ...string) (*bytes.Buffer, error) {
		inv.Verb = args[0]
		inv.Args = args[1:]
		return s.view.gocmdRunner.Run(ctx, *inv)
	}
	if err := run(invoke); err != nil {
		return nil, nil, err
	}
	var modBytes, sumBytes []byte
	modBytes, err = os.ReadFile(filepath.Join(tempDir, "go.mod"))
	if err != nil && !os.IsNotExist(err) {
		return nil, nil, err
	}
	sumBytes, err = os.ReadFile(filepath.Join(tempDir, "go.sum"))
	if err != nil && !os.IsNotExist(err) {
		return nil, nil, err
	}
	return modBytes, sumBytes, nil
}

// TempModDir creates a temporary directory with the contents of the provided
// modURI, as well as its corresponding go.sum file, if it exists. On success,
// it is the caller's responsibility to call the cleanup function to remove the
// directory when it is no longer needed.
func TempModDir(ctx context.Context, fs file.Source, modURI protocol.DocumentURI) (dir string, _ func(), rerr error) {
	dir, err := os.MkdirTemp("", "gopls-tempmod")
	if err != nil {
		return "", nil, err
	}
	cleanup := func() {
		if err := os.RemoveAll(dir); err != nil {
			event.Error(ctx, "cleaning temp dir", err)
		}
	}
	defer func() {
		if rerr != nil {
			cleanup()
		}
	}()

	// If go.mod exists, write it.
	modFH, err := fs.ReadFile(ctx, modURI)
	if err != nil {
		return "", nil, err // context cancelled
	}
	if data, err := modFH.Content(); err == nil {
		if err := os.WriteFile(filepath.Join(dir, "go.mod"), data, 0666); err != nil {
			return "", nil, err
		}
	}

	// If go.sum exists, write it.
	sumURI := protocol.DocumentURI(strings.TrimSuffix(string(modURI), ".mod") + ".sum")
	sumFH, err := fs.ReadFile(ctx, sumURI)
	if err != nil {
		return "", nil, err // context cancelled
	}
	if data, err := sumFH.Content(); err == nil {
		if err := os.WriteFile(filepath.Join(dir, "go.sum"), data, 0666); err != nil {
			return "", nil, err
		}
	}

	return dir, cleanup, nil
}

// AllowNetwork determines whether Go commands are permitted to use the
// network. (Controlled via GOPROXY=off.)
type AllowNetwork bool

const (
	NoNetwork AllowNetwork = false
	NetworkOK AllowNetwork = true
)

// GoCommandInvocation populates inv with configuration for running go commands
// on the snapshot.
//
// On success, the caller must call the cleanup function exactly once
// when the invocation is no longer needed.
//
// TODO(rfindley): although this function has been simplified significantly,
// additional refactoring is still required: the responsibility for Env and
// BuildFlags should be more clearly expressed in the API.
//
// If allowNetwork is NoNetwork, set GOPROXY=off.
func (s *Snapshot) GoCommandInvocation(allowNetwork AllowNetwork, dir, verb string, args []string, env ...string) (_ *gocommand.Invocation, cleanup func(), _ error) {
	inv := &gocommand.Invocation{
		Verb:       verb,
		Args:       args,
		WorkingDir: dir,
		Env:        append(s.view.Env(), env...),
		BuildFlags: slices.Clone(s.Options().BuildFlags),
	}
	if !allowNetwork {
		inv.Env = append(inv.Env, "GOPROXY=off")
	}

	// Write overlay files for unsaved editor buffers.
	overlay, cleanup, err := gocommand.WriteOverlays(s.buildOverlays())
	if err != nil {
		return nil, nil, err
	}
	inv.Overlay = overlay
	return inv, cleanup, nil
}

// buildOverlays returns a new mapping from logical file name to
// effective content, for each unsaved editor buffer, in the same form
// as [packages.Cfg]'s Overlay field.
func (s *Snapshot) buildOverlays() map[string][]byte {
	overlays := make(map[string][]byte)
	for _, overlay := range s.Overlays() {
		if overlay.saved {
			continue
		}
		// TODO(rfindley): previously, there was a todo here to make sure we don't
		// send overlays outside of the current view. IMO we should instead make
		// sure this doesn't matter.
		overlays[overlay.URI().Path()] = overlay.content
	}
	return overlays
}

// Overlays returns the set of overlays at this snapshot.
//
// Note that this may differ from the set of overlays on the server, if the
// snapshot observed a historical state.
func (s *Snapshot) Overlays() []*overlay {
	s.mu.Lock()
	defer s.mu.Unlock()

	return s.files.getOverlays()
}

// Package data kinds, identifying various package data that may be stored in
// the file cache.
const (
	xrefsKind       = "xrefs"
	methodSetsKind  = "methodsets"
	testsKind       = "tests"
	exportDataKind  = "export"
	diagnosticsKind = "diagnostics"
	typerefsKind    = "typerefs"
	symbolsKind     = "symbols"
)

// PackageDiagnostics returns diagnostics for files contained in specified
// packages.
//
// If these diagnostics cannot be loaded from cache, the requested packages
// may be type-checked.
func (s *Snapshot) PackageDiagnostics(ctx context.Context, ids ...PackageID) (map[protocol.DocumentURI][]*Diagnostic, error) {
	ctx, done := event.Start(ctx, "cache.snapshot.PackageDiagnostics")
	defer done()

	var mu sync.Mutex
	perFile := make(map[protocol.DocumentURI][]*Diagnostic)
	collect := func(diags []*Diagnostic) {
		mu.Lock()
		defer mu.Unlock()
		for _, diag := range diags {
			perFile[diag.URI] = append(perFile[diag.URI], diag)
		}
	}
	pre := func(_ int, ph *packageHandle) bool {
		data, err := filecache.Get(diagnosticsKind, ph.key)
		if err == nil { // hit
			collect(ph.loadDiagnostics)
			collect(decodeDiagnostics(data))
			return false
		} else if err != filecache.ErrNotFound {
			event.Error(ctx, "reading diagnostics from filecache", err)
		}
		return true
	}
	post := func(_ int, pkg *Package) {
		collect(pkg.loadDiagnostics)
		collect(pkg.pkg.diagnostics)
	}
	return perFile, s.forEachPackage(ctx, ids, pre, post)
}

// References returns cross-reference indexes for the specified packages.
//
// If these indexes cannot be loaded from cache, the requested packages may
// be type-checked.
func (s *Snapshot) References(ctx context.Context, ids ...PackageID) ([]xrefIndex, error) {
	ctx, done := event.Start(ctx, "cache.snapshot.References")
	defer done()

	indexes := make([]xrefIndex, len(ids))
	pre := func(i int, ph *packageHandle) bool {
		data, err := filecache.Get(xrefsKind, ph.key)
		if err == nil { // hit
			indexes[i] = xrefIndex{mp: ph.mp, data: data}
			return false
		} else if err != filecache.ErrNotFound {
			event.Error(ctx, "reading xrefs from filecache", err)
		}
		return true
	}
	post := func(i int, pkg *Package) {
		indexes[i] = xrefIndex{mp: pkg.metadata, data: pkg.pkg.xrefs()}
	}
	return indexes, s.forEachPackage(ctx, ids, pre, post)
}

// An xrefIndex is a helper for looking up references in a given package.
type xrefIndex struct {
	mp   *metadata.Package
	data []byte
}

func (index xrefIndex) Lookup(targets map[PackagePath]map[objectpath.Path]struct{}) []protocol.Location {
	return xrefs.Lookup(index.mp, index.data, targets)
}

// MethodSets returns method-set indexes for the specified packages.
//
// If these indexes cannot be loaded from cache, the requested packages may
// be type-checked.
func (s *Snapshot) MethodSets(ctx context.Context, ids ...PackageID) ([]*methodsets.Index, error) {
	ctx, done := event.Start(ctx, "cache.snapshot.MethodSets")
	defer done()

	indexes := make([]*methodsets.Index, len(ids))
	pre := func(i int, ph *packageHandle) bool {
		data, err := filecache.Get(methodSetsKind, ph.key)
		if err == nil { // hit
			indexes[i] = methodsets.Decode(ph.mp.PkgPath, data)
			return false
		} else if err != filecache.ErrNotFound {
			event.Error(ctx, "reading methodsets from filecache", err)
		}
		return true
	}
	post := func(i int, pkg *Package) {
		indexes[i] = pkg.pkg.methodsets()
	}
	return indexes, s.forEachPackage(ctx, ids, pre, post)
}

// Tests returns test-set indexes for the specified packages. There is a
// one-to-one correspondence between ID and Index.
//
// If these indexes cannot be loaded from cache, the requested packages may be
// type-checked.
func (s *Snapshot) Tests(ctx context.Context, ids ...PackageID) ([]*testfuncs.Index, error) {
	ctx, done := event.Start(ctx, "cache.snapshot.Tests")
	defer done()

	indexes := make([]*testfuncs.Index, len(ids))
	pre := func(i int, ph *packageHandle) bool {
		data, err := filecache.Get(testsKind, ph.key)
		if err == nil { // hit
			indexes[i] = testfuncs.Decode(data)
			return false
		} else if err != filecache.ErrNotFound {
			event.Error(ctx, "reading tests from filecache", err)
		}
		return true
	}
	post := func(i int, pkg *Package) {
		indexes[i] = pkg.pkg.tests()
	}
	return indexes, s.forEachPackage(ctx, ids, pre, post)
}

// NarrowestMetadataForFile returns metadata for the narrowest package
// (the one with the fewest files) that encloses the specified file.
// The result may be a test variant, but never an intermediate test variant.
func (snapshot *Snapshot) NarrowestMetadataForFile(ctx context.Context, uri protocol.DocumentURI) (*metadata.Package, error) {
	mps, err := snapshot.MetadataForFile(ctx, uri, true)
	if err != nil {
		return nil, err
	}
	if len(mps) == 0 {
		return nil, fmt.Errorf("no package metadata for file %s", uri)
	}
	return mps[0], nil
}

// MetadataForFile returns a new slice containing metadata for each
// package containing the Go file identified by uri, ordered by the
// number of CompiledGoFiles (i.e. "narrowest" to "widest" package),
// and secondarily by IsIntermediateTestVariant (false < true).
// The result may include tests and intermediate test variants of
// importable packages. If removeIntermediateTestVariants is provided,
// intermediate test variants will be excluded.
// It returns an error if the context was cancelled.
func (s *Snapshot) MetadataForFile(ctx context.Context, uri protocol.DocumentURI, removeIntermediateTestVariants bool) ([]*metadata.Package, error) {
	if s.view.typ == AdHocView {
		// As described in golang/go#57209, in ad-hoc workspaces (where we load ./
		// rather than ./...), preempting the directory load with file loads can
		// lead to an inconsistent outcome, where certain files are loaded with
		// command-line-arguments packages and others are loaded only in the ad-hoc
		// package. Therefore, ensure that the workspace is loaded before doing any
		// file loads.
		if err := s.awaitLoaded(ctx); err != nil {
			return nil, err
		}
	}

	s.mu.Lock()

	// Start with the set of package associations derived from the last load.
	pkgs := s.meta.ForFile[uri]

	shouldLoad := false // whether any packages containing uri are marked 'shouldLoad'
	for _, pkg := range pkgs {
		if p, _ := s.shouldLoad.Get(pkg.ID); len(p) > 0 {
			shouldLoad = true
		}
	}

	// Check if uri is known to be unloadable.
	unloadable := s.unloadableFiles.Contains(uri)

	s.mu.Unlock()

	// Reload if loading is likely to improve the package associations for uri:
	//  - uri is not contained in any valid packages
	//  - ...or one of the packages containing uri is marked 'shouldLoad'
	//  - ...but uri is not unloadable
	if (shouldLoad || len(pkgs) == 0) && !unloadable {
		scope := fileLoadScope(uri)
		err := s.load(ctx, NoNetwork, scope)

		// Return the context error here as the current operation is no longer
		// valid.
		if err != nil {
			// Guard against failed loads due to context cancellation. We don't want
			// to mark loads as completed if they failed due to context cancellation.
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}

			// Don't return an error here, as we may still return stale IDs.
			// Furthermore, the result of MetadataForFile should be consistent upon
			// subsequent calls, even if the file is marked as unloadable.
			if !errors.Is(err, errNoPackages) {
				event.Error(ctx, "MetadataForFile", err)
			}
		}

		// We must clear scopes after loading.
		//
		// TODO(rfindley): unlike reloadWorkspace, this is simply marking loaded
		// packages as loaded. We could do this from snapshot.load and avoid
		// raciness.
		s.clearShouldLoad(scope)
	}

	// Retrieve the metadata.
	s.mu.Lock()
	defer s.mu.Unlock()
	// TODO(rfindley): is there any reason not to make the sorting below the
	// canonical sorting, so that we don't need to mutate this slice?
	metas := slices.Clone(s.meta.ForFile[uri])

	// Metadata is only ever added by loading,
	// so if we get here and still have
	// no packages, uri is unloadable.
	if !unloadable && len(metas) == 0 {
		s.unloadableFiles.Add(uri)
	}

	if removeIntermediateTestVariants {
		metadata.RemoveIntermediateTestVariants(&metas)
	}

	// Sort packages "narrowest" to "widest" (in practice:
	// non-tests before tests), and regular packages before
	// their intermediate test variants (which have the same
	// files but different imports).
	slices.SortFunc(metas, func(x, y *metadata.Package) int {
		if sign := cmp.Compare(len(x.CompiledGoFiles), len(y.CompiledGoFiles)); sign != 0 {
			return sign
		}
		// Skip ITV-specific ordering if they were removed.
		if removeIntermediateTestVariants {
			return 0
		}
		return boolCompare(x.IsIntermediateTestVariant(), y.IsIntermediateTestVariant())
	})

	return metas, nil
}

// btoi returns int(b) as proposed in #64825.
func btoi(b bool) int {
	if b {
		return 1
	} else {
		return 0
	}
}

// boolCompare is a comparison function for booleans, returning -1 if x < y, 0
// if x == y, and 1 if x > y, where false < true.
func boolCompare(x, y bool) int {
	return btoi(x) - btoi(y)
}

// ReverseDependencies returns a new mapping whose entries are
// the ID and Metadata of each package in the workspace that
// directly or transitively depend on the package denoted by id,
// excluding id itself.
func (s *Snapshot) ReverseDependencies(ctx context.Context, id PackageID, transitive bool) (map[PackageID]*metadata.Package, error) {
	if err := s.awaitLoaded(ctx); err != nil {
		return nil, err
	}

	meta := s.MetadataGraph()
	var rdeps map[PackageID]*metadata.Package
	if transitive {
		rdeps = meta.ReverseReflexiveTransitiveClosure(id)

		// Remove the original package ID from the map.
		// (Callers all want irreflexivity but it's easier
		// to compute reflexively then subtract.)
		delete(rdeps, id)

	} else {
		// direct reverse dependencies
		rdeps = make(map[PackageID]*metadata.Package)
		for _, rdep := range meta.ImportedBy[id] {
			rdeps[rdep.ID] = rdep
		}
	}

	return rdeps, nil
}

// See Session.FileWatchingGlobPatterns for a description of gopls' file
// watching heuristic.
func (s *Snapshot) fileWatchingGlobPatterns() map[protocol.RelativePattern]unit {
	// Always watch files that may change the view definition.
	patterns := make(map[protocol.RelativePattern]unit)

	// If GOWORK is outside the folder, ensure we are watching it.
	if s.view.gowork != "" && !s.view.folder.Dir.Encloses(s.view.gowork) {
		workPattern := protocol.RelativePattern{
			BaseURI: s.view.gowork.Dir(),
			Pattern: path.Base(string(s.view.gowork)),
		}
		patterns[workPattern] = unit{}
	}

	for _, glob := range s.Options().WorkspaceFiles {
		patterns[protocol.RelativePattern{Pattern: glob}] = unit{}
	}

	var extensions strings.Builder
	extensions.WriteString("go,mod,sum,work")
	for _, ext := range s.Options().TemplateExtensions {
		extensions.WriteString(",")
		extensions.WriteString(ext)
	}
	watchGoFiles := fmt.Sprintf("**/*.{%s}", extensions.String())

	var dirs []string
	if s.view.typ.usesModules() {
		if s.view.typ == GoWorkView {
			workVendorDir := filepath.Join(s.view.gowork.DirPath(), "vendor")
			workVendorURI := protocol.URIFromPath(workVendorDir)
			patterns[protocol.RelativePattern{BaseURI: workVendorURI, Pattern: watchGoFiles}] = unit{}
		}

		// In module mode, watch directories containing active modules, and collect
		// these dirs for later filtering the set of known directories.
		//
		// The assumption is that the user is not actively editing non-workspace
		// modules, so don't pay the price of file watching.
		for modFile := range s.view.workspaceModFiles {
			dirs = append(dirs, modFile.DirPath())

			// TODO(golang/go#64724): thoroughly test these patterns, particularly on
			// on Windows.
			//
			// Note that glob patterns should use '/' on Windows:
			// https://code.visualstudio.com/docs/editor/glob-patterns
			patterns[protocol.RelativePattern{BaseURI: modFile.Dir(), Pattern: watchGoFiles}] = unit{}
		}
	} else {
		// In non-module modes (GOPATH or AdHoc), we just watch the workspace root.
		dirs = []string{s.view.root.Path()}
		patterns[protocol.RelativePattern{Pattern: watchGoFiles}] = unit{}
	}

	if s.watchSubdirs() {
		// Some clients (e.g. VS Code) do not send notifications for changes to
		// directories that contain Go code (golang/go#42348). To handle this,
		// explicitly watch all of the directories in the workspace. We find them
		// by adding the directories of every file in the snapshot's workspace
		// directories. There may be thousands of patterns, each a single
		// directory.
		//
		// We compute this set by looking at files that we've previously observed.
		// This may miss changed to directories that we haven't observed, but that
		// shouldn't matter as there is nothing to invalidate (if a directory falls
		// in forest, etc).
		//
		// (A previous iteration created a single glob pattern holding a union of
		// all the directories, but this was found to cause VS Code to get stuck
		// for several minutes after a buffer was saved twice in a workspace that
		// had >8000 watched directories.)
		//
		// Some clients (notably coc.nvim, which uses watchman for globs) perform
		// poorly with a large list of individual directories.
		s.addKnownSubdirs(patterns, dirs)
	}

	return patterns
}

func (s *Snapshot) addKnownSubdirs(patterns map[protocol.RelativePattern]unit, wsDirs []string) {
	s.mu.Lock()
	defer s.mu.Unlock()

	for dir := range s.files.getDirs().All() {
		for _, wsDir := range wsDirs {
			if pathutil.InDir(wsDir, dir) {
				patterns[protocol.RelativePattern{Pattern: filepath.ToSlash(dir)}] = unit{}
			}
		}
	}
}

// watchSubdirs reports whether gopls should request separate file watchers for
// each relevant subdirectory. This is necessary only for clients (namely VS
// Code) that do not send notifications for individual files in a directory
// when the entire directory is deleted.
func (s *Snapshot) watchSubdirs() bool {
	switch p := s.Options().SubdirWatchPatterns; p {
	case settings.SubdirWatchPatternsOn:
		return true
	case settings.SubdirWatchPatternsOff:
		return false
	case settings.SubdirWatchPatternsAuto:
		// See the documentation of InternalOptions.SubdirWatchPatterns for an
		// explanation of why VS Code gets a different default value here.
		//
		// Unfortunately, there is no authoritative list of client names, nor any
		// requirements that client names do not change. We should update the VS
		// Code extension to set a default value of "subdirWatchPatterns" to "on",
		// so that this workaround is only temporary.
		switch s.Options().ClientInfo.Name {
		case "Visual Studio Code", "Visual Studio Code - Insiders":
			return true
		default:
			return false
		}
	default:
		bug.Reportf("invalid subdirWatchPatterns: %q", p)
		return false
	}
}

// filesInDir returns all files observed by the snapshot that are contained in
// a directory with the provided URI.
func (s *Snapshot) filesInDir(uri protocol.DocumentURI) []protocol.DocumentURI {
	s.mu.Lock()
	defer s.mu.Unlock()

	dir := uri.Path()
	if !s.files.getDirs().Contains(dir) {
		return nil
	}
	var files []protocol.DocumentURI
	for uri := range s.files.all() {
		if pathutil.InDir(dir, uri.Path()) {
			files = append(files, uri)
		}
	}
	return files
}

// WorkspaceMetadata returns a new, unordered slice containing
// metadata for all ordinary and test packages (but not
// intermediate test variants) in the workspace.
//
// The workspace is the set of modules typically defined by a
// go.work file. It is not transitively closed: for example,
// the standard library is not usually part of the workspace
// even though every module in the workspace depends on it.
//
// Operations that must inspect all the dependencies of the
// workspace packages should instead use AllMetadata.
func (s *Snapshot) WorkspaceMetadata(ctx context.Context) ([]*metadata.Package, error) {
	if err := s.awaitLoaded(ctx); err != nil {
		return nil, err
	}

	s.mu.Lock()
	defer s.mu.Unlock()

	meta := make([]*metadata.Package, 0, s.workspacePackages.Len())
	for id := range s.workspacePackages.All() {
		meta = append(meta, s.meta.Packages[id])
	}
	return meta, nil
}

// WorkspacePackages returns the map of workspace package to package path.
//
// The set of workspace packages is updated after every load. A package is a
// workspace package if and only if it is present in this map.
func (s *Snapshot) WorkspacePackages() immutable.Map[PackageID, PackagePath] {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.workspacePackages
}

// IsWorkspacePackage reports whether the given package ID refers to a
// workspace package for the Snapshot. It is equivalent to looking up the
// package in [Snapshot.WorkspacePackages].
func (s *Snapshot) IsWorkspacePackage(id PackageID) bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	_, ok := s.workspacePackages.Value(id)
	return ok
}

// AllMetadata returns a new unordered array of metadata for
// all packages known to this snapshot, which includes the
// packages of all workspace modules plus their transitive
// import dependencies.
//
// It may also contain ad-hoc packages for standalone files.
// It includes all test variants.
//
// TODO(rfindley): Replace usage of function this with s.LoadMetadataGraph().
func (s *Snapshot) AllMetadata(ctx context.Context) ([]*metadata.Package, error) {
	g, err := s.LoadMetadataGraph(ctx)
	if err != nil {
		return nil, err
	}
	return moremaps.ValueSlice(g.Packages), nil
}

// GoModForFile returns the URI of the go.mod file for the given URI.
//
// TODO(rfindley): clarify that this is only active modules. Or update to just
// use findRootPattern.
func (s *Snapshot) GoModForFile(uri protocol.DocumentURI) protocol.DocumentURI {
	return moduleForURI(s.view.workspaceModFiles, uri)
}

func moduleForURI(modFiles map[protocol.DocumentURI]struct{}, uri protocol.DocumentURI) protocol.DocumentURI {
	var match protocol.DocumentURI
	for modURI := range modFiles {
		if !modURI.Dir().Encloses(uri) {
			continue
		}
		if len(modURI) > len(match) {
			match = modURI
		}
	}
	return match
}

// Metadata returns the metadata for the specified package,
// or nil if it was not found.
func (s *Snapshot) Metadata(id PackageID) *metadata.Package {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.meta.Packages[id]
}

// clearShouldLoad clears package IDs that no longer need to be reloaded after
// scopes has been loaded.
func (s *Snapshot) clearShouldLoad(scopes ...loadScope) {
	s.mu.Lock()
	defer s.mu.Unlock()

	for _, scope := range scopes {
		switch scope := scope.(type) {
		case packageLoadScope:
			scopePath := PackagePath(scope)
			var toDelete []PackageID
			for id, pkgPaths := range s.shouldLoad.All() {
				if slices.Contains(pkgPaths, scopePath) {
					toDelete = append(toDelete, id)
				}
			}
			for _, id := range toDelete {
				s.shouldLoad.Delete(id)
			}
		case fileLoadScope:
			uri := protocol.DocumentURI(scope)
			for _, pkg := range s.meta.ForFile[uri] {
				s.shouldLoad.Delete(pkg.ID)
			}
		}
	}
}

// ReadFile returns a File for the given URI. If the file is unknown it is added
// to the managed set.
//
// ReadFile succeeds even if the file does not exist. A non-nil error return
// indicates some type of internal error, for example if ctx is cancelled.
func (s *Snapshot) ReadFile(ctx context.Context, uri protocol.DocumentURI) (file.Handle, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	return lockedSnapshot{s}.ReadFile(ctx, uri)
}

// lockedSnapshot implements the file.Source interface, while holding s.mu.
//
// TODO(rfindley): This unfortunate type had been eliminated, but it had to be
// restored to fix golang/go#65801. We should endeavor to remove it again.
type lockedSnapshot struct {
	s *Snapshot
}

func (s lockedSnapshot) ReadFile(ctx context.Context, uri protocol.DocumentURI) (file.Handle, error) {
	fh, ok := s.s.files.get(uri)
	if !ok {
		var err error
		fh, err = s.s.view.fs.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		s.s.files.set(uri, fh)
	}
	return fh, nil
}

// preloadFiles delegates to the view FileSource to read the requested uris in
// parallel, without holding the snapshot lock.
func (s *Snapshot) preloadFiles(ctx context.Context, uris []protocol.DocumentURI) {
	files := make([]file.Handle, len(uris))
	var wg sync.WaitGroup
	iolimit := make(chan struct{}, 20) // I/O concurrency limiting semaphore
	for i, uri := range uris {
		wg.Add(1)
		iolimit <- struct{}{}
		go func(i int, uri protocol.DocumentURI) {
			defer wg.Done()
			fh, err := s.view.fs.ReadFile(ctx, uri)
			<-iolimit
			if err != nil && ctx.Err() == nil {
				event.Error(ctx, fmt.Sprintf("reading %s", uri), err)
				return
			}
			files[i] = fh
		}(i, uri)
	}
	wg.Wait()

	s.mu.Lock()
	defer s.mu.Unlock()

	for i, fh := range files {
		if fh == nil {
			continue // error logged above
		}
		uri := uris[i]
		if _, ok := s.files.get(uri); !ok {
			s.files.set(uri, fh)
		}
	}
}

// IsOpen returns whether the editor currently has a file open.
func (s *Snapshot) IsOpen(uri protocol.DocumentURI) bool {
	s.mu.Lock()
	defer s.mu.Unlock()

	fh, _ := s.files.get(uri)
	_, open := fh.(*overlay)
	return open
}

// MetadataGraph returns the current metadata graph for the Snapshot.
func (s *Snapshot) MetadataGraph() *metadata.Graph {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.meta
}

// LoadMetadataGraph is like [Snapshot.MetadataGraph], but awaits snapshot reloading.
func (s *Snapshot) LoadMetadataGraph(ctx context.Context) (*metadata.Graph, error) {
	if err := s.awaitLoaded(ctx); err != nil {
		return nil, err
	}
	return s.MetadataGraph(), nil
}

// InitializationError returns the last error from initialization.
func (s *Snapshot) InitializationError() *InitializationError {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.initialErr
}

// awaitLoaded awaits initialization and package reloading, and returns
// ctx.Err().
func (s *Snapshot) awaitLoaded(ctx context.Context) error {
	// Do not return results until the snapshot's view has been initialized.
	s.AwaitInitialized(ctx)
	s.reloadWorkspace(ctx)
	return ctx.Err()
}

// AwaitInitialized waits until the snapshot's view is initialized.
func (s *Snapshot) AwaitInitialized(ctx context.Context) {
	select {
	case <-ctx.Done():
		return
	case <-s.view.initialWorkspaceLoad:
	}
	// We typically prefer to run something as intensive as the IWL without
	// blocking. I'm not sure if there is a way to do that here.
	s.initialize(ctx, false)
}

// reloadWorkspace reloads the metadata for all invalidated workspace packages.
func (s *Snapshot) reloadWorkspace(ctx context.Context) {
	if ctx.Err() != nil {
		return
	}

	var scopes []loadScope
	var seen map[PackagePath]bool
	s.mu.Lock()
	for _, pkgPaths := range s.shouldLoad.All() {
		for _, pkgPath := range pkgPaths {
			if seen == nil {
				seen = make(map[PackagePath]bool)
			}
			if seen[pkgPath] {
				continue
			}
			seen[pkgPath] = true
			scopes = append(scopes, packageLoadScope(pkgPath))
		}
	}
	s.mu.Unlock()

	if len(scopes) == 0 {
		return
	}

	// For an ad-hoc view, we cannot reload by package path. Just reload the view.
	if s.view.typ == AdHocView {
		scopes = []loadScope{viewLoadScope{}}
	}

	err := s.load(ctx, NoNetwork, scopes...)

	// Unless the context was canceled, set "shouldLoad" to false for all
	// of the metadata we attempted to load.
	if !errors.Is(err, context.Canceled) {
		s.clearShouldLoad(scopes...)
		if err != nil {
			event.Error(ctx, "reloading workspace", err, s.Labels()...)
		}
	}
}

func (s *Snapshot) orphanedFileDiagnostics(ctx context.Context, overlays []*overlay) ([]*Diagnostic, error) {
	if err := s.awaitLoaded(ctx); err != nil {
		return nil, err
	}

	var diagnostics []*Diagnostic
	var orphaned []*overlay
searchOverlays:
	for _, o := range overlays {
		uri := o.URI()
		if s.IsBuiltin(uri) || s.FileKind(o) != file.Go {
			continue
		}
		mps, err := s.MetadataForFile(ctx, uri, true)
		if err != nil {
			return nil, err
		}
		for _, mp := range mps {
			if !metadata.IsCommandLineArguments(mp.ID) || mp.Standalone {
				continue searchOverlays
			}
		}

		// With zero-config gopls (golang/go#57979), orphaned file diagnostics
		// include diagnostics for orphaned files -- not just diagnostics relating
		// to the reason the files are opened.
		//
		// This is because orphaned files are never considered part of a workspace
		// package: if they are loaded by a view, that view is arbitrary, and they
		// may be loaded by multiple views. If they were to be diagnosed by
		// multiple views, their diagnostics may become inconsistent.
		if len(mps) > 0 {
			diags, err := s.PackageDiagnostics(ctx, mps[0].ID)
			if err != nil {
				return nil, err
			}
			diagnostics = append(diagnostics, diags[uri]...)
		}
		orphaned = append(orphaned, o)
	}

	if len(orphaned) == 0 {
		return nil, nil
	}

	loadedModFiles := make(map[protocol.DocumentURI]struct{}) // all mod files, including dependencies
	ignoredFiles := make(map[protocol.DocumentURI]bool)       // files reported in packages.Package.IgnoredFiles

	g := s.MetadataGraph()
	for _, meta := range g.Packages {
		if meta.Module != nil && meta.Module.GoMod != "" {
			gomod := protocol.URIFromPath(meta.Module.GoMod)
			loadedModFiles[gomod] = struct{}{}
		}
		for _, ignored := range meta.IgnoredFiles {
			ignoredFiles[ignored] = true
		}
	}

	initialErr := s.InitializationError()

	for _, fh := range orphaned {
		pgf, rng, ok := orphanedFileDiagnosticRange(ctx, s.view.parseCache, fh)
		if !ok {
			continue // e.g. cancellation or parse error
		}

		var (
			msg            string         // if non-empty, report a diagnostic with this message
			suggestedFixes []SuggestedFix // associated fixes, if any
		)
		if initialErr != nil {
			msg = fmt.Sprintf("initialization failed: %v", initialErr.MainError)
		} else if goMod, err := findRootPattern(ctx, fh.URI().Dir(), "go.mod", file.Source(s)); err == nil && goMod != "" {
			// Check if the file's module should be loadable by considering both
			// loaded modules and workspace modules. The former covers cases where
			// the file is outside of a workspace folder. The latter covers cases
			// where the file is inside a workspace module, but perhaps no packages
			// were loaded for that module.
			_, loadedMod := loadedModFiles[goMod]
			_, workspaceMod := s.view.workspaceModFiles[goMod]
			// If we have a relevant go.mod file, check whether the file is orphaned
			// due to its go.mod file being inactive. We could also offer a
			// prescriptive diagnostic in the case that there is no go.mod file, but
			// it is harder to be precise in that case, and less important.
			if !(loadedMod || workspaceMod) {
				modDir := goMod.DirPath()
				viewDir := s.view.folder.Dir.Path()

				// When the module is underneath the view dir, we offer
				// "use all modules" quick-fixes.
				inDir := pathutil.InDir(viewDir, modDir)

				if rel, err := filepath.Rel(viewDir, modDir); err == nil {
					modDir = rel
				}

				var fix string
				if s.view.folder.Env.GoVersion >= 18 {
					if s.view.gowork != "" {
						fix = fmt.Sprintf("To fix this problem, you can add this module to your go.work file (%s)", s.view.gowork)

						cmd := command.NewRunGoWorkCommandCommand("Run `go work use`", command.RunGoWorkArgs{
							ViewID: s.view.ID(),
							Args:   []string{"use", modDir},
						})
						suggestedFixes = append(suggestedFixes, SuggestedFix{
							Title:      "Use this module in your go.work file",
							Command:    cmd,
							ActionKind: protocol.QuickFix,
						})

						if inDir {
							cmd := command.NewRunGoWorkCommandCommand("Run `go work use -r`", command.RunGoWorkArgs{
								ViewID: s.view.ID(),
								Args:   []string{"use", "-r", "."},
							})
							suggestedFixes = append(suggestedFixes, SuggestedFix{
								Title:      "Use all modules in your workspace",
								Command:    cmd,
								ActionKind: protocol.QuickFix,
							})
						}
					} else {
						fix = "To fix this problem, you can add a go.work file that uses this directory."

						cmd := command.NewRunGoWorkCommandCommand("Run `go work init && go work use`", command.RunGoWorkArgs{
							ViewID:    s.view.ID(),
							InitFirst: true,
							Args:      []string{"use", modDir},
						})
						suggestedFixes = []SuggestedFix{
							{
								Title:      "Add a go.work file using this module",
								Command:    cmd,
								ActionKind: protocol.QuickFix,
							},
						}

						if inDir {
							cmd := command.NewRunGoWorkCommandCommand("Run `go work init && go work use -r`", command.RunGoWorkArgs{
								ViewID:    s.view.ID(),
								InitFirst: true,
								Args:      []string{"use", "-r", "."},
							})
							suggestedFixes = append(suggestedFixes, SuggestedFix{
								Title:      "Add a go.work file using all modules in your workspace",
								Command:    cmd,
								ActionKind: protocol.QuickFix,
							})
						}
					}
				} else {
					fix = `To work with multiple modules simultaneously, please upgrade to Go 1.18 or
later, reinstall gopls, and use a go.work file.`
				}

				msg = fmt.Sprintf(`This file is within module %q, which is not included in your workspace.
%s
See the documentation for more information on setting up your workspace:
https://github.com/golang/tools/blob/master/gopls/doc/workspace.md.`, modDir, fix)
			}
		}

		if msg == "" {
			if ignoredFiles[fh.URI()] {
				// TODO(rfindley): use the constraint package to check if the file
				// _actually_ satisfies the current build context.
				hasConstraint := false
				walkConstraints(pgf.File, func(constraint.Expr) bool {
					hasConstraint = true
					return false
				})
				var fix string
				if hasConstraint {
					fix = `This file may be excluded due to its build tags; try adding "-tags=<build tag>" to your gopls "buildFlags" configuration
See the documentation for more information on working with build tags:
https://github.com/golang/tools/blob/master/gopls/doc/settings.md#buildflags.`
				} else if strings.Contains(fh.URI().Base(), "_") {
					fix = `This file may be excluded due to its GOOS/GOARCH, or other build constraints.`
				} else {
					fix = `This file is ignored by your gopls build.` // we don't know why
				}
				msg = fmt.Sprintf("No packages found for open file %s.\n%s", fh.URI().Path(), fix)
			} else {
				// Fall back: we're not sure why the file is orphaned.
				// TODO(rfindley): we could do better here, diagnosing the lack of a
				// go.mod file and malformed file names (see the perc%ent marker test).
				msg = fmt.Sprintf("No packages found for open file %s.", fh.URI().Path())
			}
		}

		if msg != "" {
			d := &Diagnostic{
				URI:            fh.URI(),
				Range:          rng,
				Severity:       protocol.SeverityWarning,
				Source:         ListError,
				Message:        msg,
				SuggestedFixes: suggestedFixes,
			}
			if ok := bundleLazyFixes(d); !ok {
				bug.Reportf("failed to bundle quick fixes for %v", d)
			}
			// Only report diagnostics if we detect an actual exclusion.
			diagnostics = append(diagnostics, d)
		}
	}
	return diagnostics, nil
}

// orphanedFileDiagnosticRange returns the position to use for orphaned file diagnostics.
// We only warn about an orphaned file if it is well-formed enough to actually
// be part of a package. Otherwise, we need more information.
func orphanedFileDiagnosticRange(ctx context.Context, cache *parseCache, fh file.Handle) (*parsego.File, protocol.Range, bool) {
	pgfs, err := cache.parseFiles(ctx, token.NewFileSet(), parsego.Header, false, fh)
	if err != nil {
		return nil, protocol.Range{}, false
	}
	pgf := pgfs[0]
	name := pgf.File.Name
	if !name.Pos().IsValid() {
		return nil, protocol.Range{}, false
	}
	rng, err := pgf.PosRange(name.Pos(), name.End())
	if err != nil {
		return nil, protocol.Range{}, false
	}
	return pgf, rng, true
}

// TODO(golang/go#53756): this function needs to consider more than just the
// absolute URI, for example:
//   - the position of /vendor/ with respect to the relevant module root
//   - whether or not go.work is in use (as vendoring isn't supported in workspace mode)
//
// Most likely, each call site of inVendor needs to be reconsidered to
// understand and correctly implement the desired behavior.
func inVendor(uri protocol.DocumentURI) bool {
	_, after, found := strings.Cut(string(uri), "/vendor/")
	// Only subdirectories of /vendor/ are considered vendored
	// (/vendor/a/foo.go is vendored, /vendor/foo.go is not).
	return found && strings.Contains(after, "/")
}

// clone copies state from the receiver into a new Snapshot, applying the given
// state changes.
//
// The caller of clone must call Snapshot.decref on the returned
// snapshot when they are finished using it.
//
// The resulting bool reports whether the change invalidates any derived
// diagnostics for the snapshot, for example because it invalidates Packages or
// parsed go.mod files. This is used to mark a view as needing diagnosis in the
// server.
//
// TODO(rfindley): long term, it may be better to move responsibility for
// diagnostics into the Snapshot (e.g. a Snapshot.Diagnostics method), at which
// point the Snapshot could be responsible for tracking and forwarding a
// 'viewsToDiagnose' field. As is, this field is instead externalized in the
// server.viewsToDiagnose map. Moving it to the snapshot would entirely
// eliminate any 'relevance' heuristics from Session.DidModifyFiles, but would
// also require more strictness about diagnostic dependencies. For example,
// template.Diagnostics currently re-parses every time: there is no Snapshot
// data responsible for providing these diagnostics.
func (s *Snapshot) clone(ctx, bgCtx context.Context, changed StateChange, done func()) (*Snapshot, bool) {
	changedFiles := changed.Files
	ctx, stop := event.Start(ctx, "cache.snapshot.clone")
	defer stop()

	s.mu.Lock()
	defer s.mu.Unlock()

	// TODO(rfindley): reorganize this function to make the derivation of
	// needsDiagnosis clearer.
	needsDiagnosis := len(changed.CompilerOptDetails) > 0 || len(changed.ModuleUpgrades) > 0 || len(changed.Vulns) > 0

	bgCtx, cancel := context.WithCancel(bgCtx)
	result := &Snapshot{
		sequenceID:        s.sequenceID + 1,
		store:             s.store,
		refcount:          1, // Snapshots are born referenced.
		done:              done,
		view:              s.view,
		backgroundCtx:     bgCtx,
		cancel:            cancel,
		builtin:           s.builtin,
		initialized:       s.initialized,
		initialErr:        s.initialErr,
		packages:          s.packages.Clone(),
		fullAnalysisKeys:  s.fullAnalysisKeys.Clone(),
		factyAnalysisKeys: s.factyAnalysisKeys.Clone(),
		files:             s.files.clone(changedFiles),
		workspacePackages: s.workspacePackages,
		shouldLoad:        s.shouldLoad.Clone(),      // not cloneWithout: shouldLoad is cleared on loads
		unloadableFiles:   s.unloadableFiles.Clone(), // not cloneWithout: typing in a file doesn't necessarily make it loadable
		parseModHandles:   cloneWithout(s.parseModHandles, changedFiles, &needsDiagnosis),
		parseWorkHandles:  cloneWithout(s.parseWorkHandles, changedFiles, &needsDiagnosis),
		modTidyHandles:    cloneWithout(s.modTidyHandles, changedFiles, &needsDiagnosis),
		modWhyHandles:     cloneWithout(s.modWhyHandles, changedFiles, &needsDiagnosis),
		modVulnHandles:    cloneWithout(s.modVulnHandles, changedFiles, &needsDiagnosis),
		moduleUpgrades:    cloneWith(s.moduleUpgrades, changed.ModuleUpgrades),
		vulns:             cloneWith(s.vulns, changed.Vulns),
	}

	// Compute the new set of packages for which we want compiler
	// optimization details, after applying changed.CompilerOptDetails.
	if len(s.compilerOptDetails) > 0 || len(changed.CompilerOptDetails) > 0 {
		newCompilerOptDetails := make(map[protocol.DocumentURI]unit)
		for dir := range s.compilerOptDetails {
			if _, ok := changed.CompilerOptDetails[dir]; !ok {
				newCompilerOptDetails[dir] = unit{} // no change
			}
		}
		for dir, want := range changed.CompilerOptDetails {
			if want {
				newCompilerOptDetails[dir] = unit{}
			}
		}
		if len(newCompilerOptDetails) > 0 {
			result.compilerOptDetails = newCompilerOptDetails
		}
	}

	reinit := false
	for _, mod := range changed.Modifications {
		// Changes to vendor tree may require reinitialization,
		// either because of an initialization error
		// (e.g. "inconsistent vendoring detected"), or because
		// one or more modules may have moved into or out of the
		// vendor tree after 'go mod vendor' or 'rm -fr vendor/'.
		//
		// In this case, we consider the actual modification to see if was a creation
		// or deletion.
		//
		// TODO(rfindley): revisit the location of this check.
		if inVendor(mod.URI) && (mod.Action == file.Create || mod.Action == file.Delete) ||
			strings.HasSuffix(string(mod.URI), "/vendor/modules.txt") {

			reinit = true
			break
		}

		// Changes to workspace files, as a rule of thumb, should require reinitialization. Since their behavior
		// is generally user-defined, we want to do something sensible by re-triggering a query to the active GOPACKAGESDRIVER,
		// and reloading the state of the workspace.
		if isWorkspaceFile(mod.URI, s.view.folder.Options.WorkspaceFiles) && (mod.Action == file.Save || mod.OnDisk) {
			reinit = true
			break
		}
	}

	// Collect observed file handles for changed URIs from the old snapshot, if
	// they exist. Importantly, we don't call ReadFile here: consider the case
	// where a file is added on disk; we don't want to read the newly added file
	// into the old snapshot, as that will break our change detection below.
	//
	// TODO(rfindley): it may be more accurate to rely on the modification type
	// here, similarly to what we do for vendored files above. If we happened not
	// to have read a file in the previous snapshot, that's not the same as it
	// actually being created.
	oldFiles := make(map[protocol.DocumentURI]file.Handle)
	for uri := range changedFiles {
		if fh, ok := s.files.get(uri); ok {
			oldFiles[uri] = fh
		}
	}
	// changedOnDisk determines if the new file handle may have changed on disk.
	// It over-approximates, returning true if the new file is saved and either
	// the old file wasn't saved, or the on-disk contents changed.
	//
	// oldFH may be nil.
	changedOnDisk := func(oldFH, newFH file.Handle) bool {
		if !newFH.SameContentsOnDisk() {
			return false
		}
		if oe, ne := (oldFH != nil && fileExists(oldFH)), fileExists(newFH); !oe || !ne {
			return oe != ne
		}
		return !oldFH.SameContentsOnDisk() || oldFH.Identity() != newFH.Identity()
	}

	// Reinitialize if any workspace mod file has changed on disk.
	for uri, newFH := range changedFiles {
		if _, ok := result.view.workspaceModFiles[uri]; ok && changedOnDisk(oldFiles[uri], newFH) {
			reinit = true
		}
	}

	// Finally, process sumfile changes that may affect loading.
	for uri, newFH := range changedFiles {
		if !changedOnDisk(oldFiles[uri], newFH) {
			continue // like with go.mod files, we only reinit when things change on disk
		}
		dir, base := filepath.Split(uri.Path())
		if base == "go.work.sum" && s.view.typ == GoWorkView && dir == s.view.gowork.DirPath() {
			reinit = true
		}
		if base == "go.sum" {
			modURI := protocol.URIFromPath(filepath.Join(dir, "go.mod"))
			if _, active := result.view.workspaceModFiles[modURI]; active {
				reinit = true
			}
		}
	}

	// The snapshot should be initialized if either s was uninitialized, or we've
	// detected a change that triggers reinitialization.
	if reinit {
		result.initialized = false
		needsDiagnosis = true
	}

	// directIDs keeps track of package IDs that have directly changed.
	// Note: this is not a set, it's a map from id to invalidateMetadata.
	directIDs := map[PackageID]bool{}

	// Invalidate all package metadata if the workspace module has changed.
	if reinit {
		for k := range s.meta.Packages {
			// TODO(rfindley): this seems brittle; can we just start over?
			directIDs[k] = true
		}
	}

	// Compute invalidations based on file changes.
	anyImportDeleted := false      // import deletions can resolve cycles
	anyFileOpenedOrClosed := false // opened files affect workspace packages
	anyPkgFileChanged := false     // adding a file to a package can resolve missing dependencies

	for uri, newFH := range changedFiles {
		// The original FileHandle for this URI is cached on the snapshot.
		oldFH := oldFiles[uri] // may be nil
		_, oldOpen := oldFH.(*overlay)
		_, newOpen := newFH.(*overlay)

		// TODO(rfindley): consolidate with 'metadataChanges' logic below, which
		// also considers existential changes.
		anyFileOpenedOrClosed = anyFileOpenedOrClosed || (oldOpen != newOpen)
		anyPkgFileChanged = anyPkgFileChanged || (oldFH == nil || !fileExists(oldFH)) && fileExists(newFH)

		// If uri is a Go file, check if it has changed in a way that would
		// invalidate metadata. Note that we can't use s.view.FileKind here,
		// because the file type that matters is not what the *client* tells us,
		// but what the Go command sees.
		var invalidateMetadata, pkgFileChanged, importDeleted bool
		if strings.HasSuffix(uri.Path(), ".go") {
			invalidateMetadata, pkgFileChanged, importDeleted = metadataChanges(ctx, s, oldFH, newFH)
		}
		if invalidateMetadata {
			// If this is a metadata-affecting change, perhaps a reload will succeed.
			result.unloadableFiles.Remove(uri)
			needsDiagnosis = true
		}

		invalidateMetadata = invalidateMetadata || reinit
		anyImportDeleted = anyImportDeleted || importDeleted
		anyPkgFileChanged = anyPkgFileChanged || pkgFileChanged

		// Mark all of the package IDs containing the given file.
		filePackageIDs := invalidatedPackageIDs(uri, s.meta.ForFile, pkgFileChanged)
		for id := range filePackageIDs {
			directIDs[id] = directIDs[id] || invalidateMetadata // may insert 'false'
		}

		// Invalidate the previous modTidyHandle if any of the files have been
		// saved or if any of the metadata has been invalidated.
		//
		// TODO(rfindley): this seems like too-aggressive invalidation of mod
		// results. We should instead thread through overlays to the Go command
		// invocation and only run this if invalidateMetadata (and perhaps then
		// still do it less frequently).
		if invalidateMetadata || fileWasSaved(oldFH, newFH) {
			// Only invalidate mod tidy results for the most relevant modfile in the
			// workspace. This is a potentially lossy optimization for workspaces
			// with many modules (such as google-cloud-go, which has 145 modules as
			// of writing).
			//
			// While it is theoretically possible that a change in workspace module A
			// could affect the mod-tidiness of workspace module B (if B transitively
			// requires A), such changes are probably unlikely and not worth the
			// penalty of re-running go mod tidy for everything. Note that mod tidy
			// ignores GOWORK, so the two modules would have to be related by a chain
			// of replace directives.
			//
			// We could improve accuracy by inspecting replace directives, using
			// overlays in go mod tidy, and/or checking for metadata changes from the
			// on-disk content.
			//
			// Note that we iterate the modTidyHandles map here, rather than e.g.
			// using nearestModFile, because we don't have access to an accurate
			// FileSource at this point in the snapshot clone.
			const onlyInvalidateMostRelevant = true
			if onlyInvalidateMostRelevant {
				deleteMostRelevantModFile(result.modTidyHandles, uri)
			} else {
				result.modTidyHandles.Clear()
			}

			// TODO(rfindley): should we apply the above heuristic to mod vuln or mod
			// why handles as well?
			//
			// TODO(rfindley): no tests fail if I delete the line below.
			result.modWhyHandles.Clear()
			result.modVulnHandles.Clear()
		}
	}

	// Deleting an import can cause list errors due to import cycles to be
	// resolved. The best we can do without parsing the list error message is to
	// hope that list errors may have been resolved by a deleted import.
	//
	// We could do better by parsing the list error message. We already do this
	// to assign a better range to the list error, but for such critical
	// functionality as metadata, it's better to be conservative until it proves
	// impractical.
	//
	// We could also do better by looking at which imports were deleted and
	// trying to find cycles they are involved in. This fails when the file goes
	// from an unparsable state to a parseable state, as we don't have a
	// starting point to compare with.
	if anyImportDeleted {
		for id, mp := range s.meta.Packages {
			if len(mp.Errors) > 0 {
				directIDs[id] = true
			}
		}
	}

	// Adding a file can resolve missing dependencies from existing packages.
	//
	// We could be smart here and try to guess which packages may have been
	// fixed, but until that proves necessary, just invalidate metadata for any
	// package with missing dependencies.
	if anyPkgFileChanged {
		for id, mp := range s.meta.Packages {
			for _, impID := range mp.DepsByImpPath {
				if impID == "" { // missing import
					directIDs[id] = true
					break
				}
			}
		}
	}

	// Invalidate reverse dependencies too.
	// idsToInvalidate keeps track of transitive reverse dependencies.
	// If an ID is present in the map, invalidate its types.
	// If an ID's value is true, invalidate its metadata too.
	idsToInvalidate := map[PackageID]bool{}
	var addRevDeps func(PackageID, bool)
	addRevDeps = func(id PackageID, invalidateMetadata bool) {
		current, seen := idsToInvalidate[id]
		newInvalidateMetadata := current || invalidateMetadata

		// If we've already seen this ID, and the value of invalidate
		// metadata has not changed, we can return early.
		if seen && current == newInvalidateMetadata {
			return
		}
		idsToInvalidate[id] = newInvalidateMetadata
		for _, rdep := range s.meta.ImportedBy[id] {
			addRevDeps(rdep.ID, invalidateMetadata)
		}
	}
	for id, invalidateMetadata := range directIDs {
		addRevDeps(id, invalidateMetadata)
	}

	// Invalidated package information.
	for id, invalidateMetadata := range idsToInvalidate {
		// See the [packageHandle] documentation for more details about this
		// invalidation.
		if ph, ok := result.packages.Get(id); ok {
			needsDiagnosis = true

			// Always invalidate analysis keys, as we do not implement fine-grained
			// invalidation for analysis.
			result.fullAnalysisKeys.Delete(id)
			result.factyAnalysisKeys.Delete(id)

			if invalidateMetadata {
				result.packages.Delete(id)
			} else {
				// If the package was just invalidated by a dependency, its local
				// inputs are still valid.
				ph = ph.clone()
				if _, ok := directIDs[id]; ok {
					ph.state = validMetadata // local inputs changed
				} else {
					ph.state = min(ph.state, validLocalData) // a dependency changed
				}
				result.packages.Set(id, ph, nil)
			}
		}
	}

	// Compute which metadata updates are required. We only need to invalidate
	// packages directly containing the affected file, and only if it changed in
	// a relevant way.
	metadataUpdates := make(map[PackageID]*metadata.Package)
	for id, mp := range s.meta.Packages {
		invalidateMetadata := idsToInvalidate[id]

		// For metadata that has been newly invalidated, capture package paths
		// requiring reloading in the shouldLoad map.
		if invalidateMetadata && !metadata.IsCommandLineArguments(mp.ID) {
			needsReload := []PackagePath{mp.PkgPath}
			if mp.ForTest != "" && mp.ForTest != mp.PkgPath {
				// When reloading test variants, always reload their ForTest package as
				// well. Otherwise, we may miss test variants in the resulting load.
				//
				// TODO(rfindley): is this actually sufficient? Is it possible that
				// other test variants may be invalidated? Either way, we should
				// determine exactly what needs to be reloaded here.
				needsReload = append(needsReload, mp.ForTest)
			}
			result.shouldLoad.Set(id, needsReload, nil)
		}

		// Check whether the metadata should be deleted.
		if invalidateMetadata {
			needsDiagnosis = true
			metadataUpdates[id] = nil
			continue
		}
	}

	// Update metadata, if necessary.
	result.meta = s.meta.Update(metadataUpdates)

	// Update workspace and active packages, if necessary.
	if result.meta != s.meta || anyFileOpenedOrClosed {
		needsDiagnosis = true
		result.workspacePackages = computeWorkspacePackagesLocked(ctx, result, result.meta)
	} else {
		result.workspacePackages = s.workspacePackages
	}

	return result, needsDiagnosis
}

// cloneWithout clones m then deletes from it the keys of changes.
//
// The optional didDelete variable is set to true if there were deletions.
func cloneWithout[K constraints.Ordered, V1, V2 any](m *persistent.Map[K, V1], changes map[K]V2, didDelete *bool) *persistent.Map[K, V1] {
	m2 := m.Clone()
	for k := range changes {
		if m2.Delete(k) && didDelete != nil {
			*didDelete = true
		}
	}
	return m2
}

// cloneWith clones m then inserts the changes into it.
func cloneWith[K constraints.Ordered, V any](m *persistent.Map[K, V], changes map[K]V) *persistent.Map[K, V] {
	m2 := m.Clone()
	for k, v := range changes {
		m2.Set(k, v, nil)
	}
	return m2
}

// deleteMostRelevantModFile deletes the mod file most likely to be the mod
// file for the changed URI, if it exists.
//
// Specifically, this is the longest mod file path in a directory containing
// changed. This might not be accurate if there is another mod file closer to
// changed that happens not to be present in the map, but that's OK: the goal
// of this function is to guarantee that IF the nearest mod file is present in
// the map, it is invalidated.
func deleteMostRelevantModFile(m *persistent.Map[protocol.DocumentURI, *memoize.Promise], changed protocol.DocumentURI) {
	var mostRelevant protocol.DocumentURI
	changedFile := changed.Path()

	for modURI := range m.All() {
		if len(modURI) > len(mostRelevant) {
			if pathutil.InDir(modURI.DirPath(), changedFile) {
				mostRelevant = modURI
			}
		}
	}
	if mostRelevant != "" {
		m.Delete(mostRelevant)
	}
}

// invalidatedPackageIDs returns all packages invalidated by a change to uri.
// If we haven't seen this URI before, we guess based on files in the same
// directory. This is of course incorrect in build systems where packages are
// not organized by directory.
//
// If packageFileChanged is set, the file is either a new file, or has a new
// package name. In this case, all known packages in the directory will be
// invalidated.
func invalidatedPackageIDs(uri protocol.DocumentURI, known map[protocol.DocumentURI][]*metadata.Package, packageFileChanged bool) map[PackageID]struct{} {
	invalidated := make(map[PackageID]struct{})

	// At a minimum, we invalidate packages known to contain uri.
	for _, pkg := range known[uri] {
		invalidated[pkg.ID] = struct{}{}
	}

	// If the file didn't move to a new package, we should only invalidate the
	// packages it is currently contained inside.
	if !packageFileChanged && len(invalidated) > 0 {
		return invalidated
	}

	// This is a file we don't yet know about, or which has moved packages. Guess
	// relevant packages by considering files in the same directory.

	// Cache of FileInfo to avoid unnecessary stats for multiple files in the
	// same directory.
	stats := make(map[string]struct {
		os.FileInfo
		error
	})
	getInfo := func(dir string) (os.FileInfo, error) {
		if res, ok := stats[dir]; ok {
			return res.FileInfo, res.error
		}
		fi, err := os.Stat(dir)
		stats[dir] = struct {
			os.FileInfo
			error
		}{fi, err}
		return fi, err
	}
	dir := uri.DirPath()
	fi, err := getInfo(dir)
	if err == nil {
		// Aggregate all possibly relevant package IDs.
		for knownURI, pkgs := range known {
			knownDir := knownURI.DirPath()
			knownFI, err := getInfo(knownDir)
			if err != nil {
				continue
			}
			if os.SameFile(fi, knownFI) {
				for _, pkg := range pkgs {
					invalidated[pkg.ID] = struct{}{}
				}
			}
		}
	}
	return invalidated
}

// fileWasSaved reports whether the FileHandle passed in has been saved. It
// accomplishes this by checking to see if the original and current FileHandles
// are both overlays, and if the current FileHandle is saved while the original
// FileHandle was not saved.
func fileWasSaved(originalFH, currentFH file.Handle) bool {
	if originalFH == nil || currentFH == nil {
		return true // should not happen for valid file handles
	}

	// If the file identity has not changed, the content has not changed.
	// Therefore, the "saved" state (from the perspective of go mod tidy)
	// has not changed.
	if originalFH.Identity() == currentFH.Identity() {
		return false
	}
	c, ok := currentFH.(*overlay)
	if !ok || c == nil {
		return true
	}
	o, ok := originalFH.(*overlay)
	if !ok || o == nil {
		return c.saved
	}
	return !o.saved && c.saved
}

// metadataChanges detects features of the change from oldFH->newFH that may
// affect package metadata.
//
// It uses lockedSnapshot to access cached parse information. lockedSnapshot
// must be locked.
//
// The result parameters have the following meaning:
//   - invalidate means that package metadata for packages containing the file
//     should be invalidated.
//   - pkgFileChanged means that the file->package associates for the file have
//     changed (possibly because the file is new, or because its package name has
//     changed).
//   - importDeleted means that an import has been deleted, or we can't
//     determine if an import was deleted due to errors.
func metadataChanges(ctx context.Context, lockedSnapshot *Snapshot, oldFH, newFH file.Handle) (invalidate, pkgFileChanged, importDeleted bool) {
	if oe, ne := oldFH != nil && fileExists(oldFH), fileExists(newFH); !oe || !ne { // existential changes
		changed := oe != ne
		return changed, changed, !ne // we don't know if an import was deleted
	}

	// If the file hasn't changed, there's no need to reload.
	if oldFH.Identity() == newFH.Identity() {
		return false, false, false
	}

	fset := token.NewFileSet()
	// Parse headers to compare package names and imports.
	oldHeads, oldErr := lockedSnapshot.view.parseCache.parseFiles(ctx, fset, parsego.Header, false, oldFH)
	newHeads, newErr := lockedSnapshot.view.parseCache.parseFiles(ctx, fset, parsego.Header, false, newFH)

	if oldErr != nil || newErr != nil {
		errChanged := (oldErr == nil) != (newErr == nil)
		return errChanged, errChanged, (newErr != nil) // we don't know if an import was deleted
	}

	oldHead := oldHeads[0]
	newHead := newHeads[0]

	// `go list` fails completely if the file header cannot be parsed. If we go
	// from a non-parsing state to a parsing state, we should reload.
	if oldHead.ParseErr != nil && newHead.ParseErr == nil {
		return true, true, true // We don't know what changed, so fall back on full invalidation.
	}

	// If a package name has changed, the set of package imports may have changed
	// in ways we can't detect here. Assume an import has been deleted.
	if oldHead.File.Name.Name != newHead.File.Name.Name {
		return true, true, true
	}

	// Check whether package imports have changed. Only consider potentially
	// valid imports paths.
	oldImports := validImportPaths(oldHead.File.Imports)
	newImports := validImportPaths(newHead.File.Imports)

	for path := range newImports {
		if _, ok := oldImports[path]; ok {
			delete(oldImports, path)
		} else {
			invalidate = true // a new, potentially valid import was added
		}
	}

	if len(oldImports) > 0 {
		invalidate = true
		importDeleted = true
	}

	// If the change does not otherwise invalidate metadata, get the full ASTs in
	// order to check magic comments.
	//
	// Note: if this affects performance we can probably avoid parsing in the
	// common case by first scanning the source for potential comments.
	if !invalidate {
		origFulls, oldErr := lockedSnapshot.view.parseCache.parseFiles(ctx, fset, parsego.Full, false, oldFH)
		newFulls, newErr := lockedSnapshot.view.parseCache.parseFiles(ctx, fset, parsego.Full, false, newFH)
		if oldErr == nil && newErr == nil {
			invalidate = magicCommentsChanged(origFulls[0].File, newFulls[0].File)
		} else {
			// At this point, we shouldn't ever fail to produce a parsego.File, as
			// we're already past header parsing.
			bug.Reportf("metadataChanges: unparsable file %v (old error: %v, new error: %v)", oldFH.URI(), oldErr, newErr)
		}
	}

	return invalidate, pkgFileChanged, importDeleted
}

func magicCommentsChanged(original *ast.File, current *ast.File) bool {
	oldComments := extractMagicComments(original)
	newComments := extractMagicComments(current)
	if len(oldComments) != len(newComments) {
		return true
	}
	for i := range oldComments {
		if oldComments[i] != newComments[i] {
			return true
		}
	}
	return false
}

// validImportPaths extracts the set of valid import paths from imports.
func validImportPaths(imports []*ast.ImportSpec) map[string]struct{} {
	m := make(map[string]struct{})
	for _, spec := range imports {
		if path := spec.Path.Value; validImportPath(path) {
			m[path] = struct{}{}
		}
	}
	return m
}

func validImportPath(path string) bool {
	path, err := strconv.Unquote(path)
	if err != nil {
		return false
	}
	if path == "" {
		return false
	}
	if path[len(path)-1] == '/' {
		return false
	}
	return true
}

var buildConstraintOrEmbedRe = regexp.MustCompile(`^//(go:embed|go:build|\s*\+build).*`)

// extractMagicComments finds magic comments that affect metadata in f.
func extractMagicComments(f *ast.File) []string {
	var results []string
	for _, cg := range f.Comments {
		for _, c := range cg.List {
			if buildConstraintOrEmbedRe.MatchString(c.Text) {
				results = append(results, c.Text)
			}
		}
	}
	return results
}

// BuiltinFile returns the pseudo-source file builtins.go,
// parsed with legacy ast.Object resolution.
func (s *Snapshot) BuiltinFile(ctx context.Context) (*parsego.File, error) {
	s.AwaitInitialized(ctx)

	s.mu.Lock()
	builtin := s.builtin
	s.mu.Unlock()

	if builtin == "" {
		return nil, fmt.Errorf("no builtin package for view %s", s.view.folder.Name)
	}

	fh, err := s.ReadFile(ctx, builtin)
	if err != nil {
		return nil, err
	}
	// For the builtin file only, we need syntactic object resolution
	// (since we can't type check).
	mode := parsego.Full &^ parser.SkipObjectResolution
	pgfs, err := s.view.parseCache.parseFiles(ctx, token.NewFileSet(), mode, false, fh)
	if err != nil {
		return nil, err
	}
	return pgfs[0], nil
}

// IsBuiltin reports whether uri is part of the builtin package.
func (s *Snapshot) IsBuiltin(uri protocol.DocumentURI) bool {
	s.mu.Lock()
	defer s.mu.Unlock()
	// We should always get the builtin URI in a canonical form, so use simple
	// string comparison here. span.CompareURI is too expensive.
	return uri == s.builtin
}

func (s *Snapshot) setBuiltin(path string) {
	s.mu.Lock()
	defer s.mu.Unlock()

	s.builtin = protocol.URIFromPath(path)
}

// WantCompilerOptDetails reports whether to compute compiler
// optimization details for packages and tests in the given directory.
func (s *Snapshot) WantCompilerOptDetails(dir protocol.DocumentURI) bool {
	_, ok := s.compilerOptDetails[dir]
	return ok
}

// A CodeLensSourceFunc is a function that reports CodeLenses (range-associated
// commands) for a given file.
type CodeLensSourceFunc func(context.Context, *Snapshot, file.Handle) ([]protocol.CodeLens, error)


================================================
FILE: gopls/internal/cache/source.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"log"
	"maps"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/symbols"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/internal/imports"
)

// goplsSource is an imports.Source that provides import information using
// gopls and the module cache index.
type goplsSource struct {
	snapshot  *Snapshot
	envSource *imports.ProcessEnvSource

	// set by each invocation of ResolveReferences
	ctx context.Context
}

func (s *Snapshot) NewGoplsSource(is *imports.ProcessEnvSource) *goplsSource {
	return &goplsSource{
		snapshot:  s,
		envSource: is,
	}
}

func (s *goplsSource) LoadPackageNames(ctx context.Context, srcDir string, paths []imports.ImportPath) (map[imports.ImportPath]imports.PackageName, error) {
	// TODO: use metadata graph. Aside from debugging, this is the only used of envSource
	return s.envSource.LoadPackageNames(ctx, srcDir, paths)
}

type result struct {
	res        *imports.Result
	deprecated bool
}

// ResolveReferences tries to find resolving imports in the workspace, and failing
// that, in the module cache. It uses heuristics to decide among alternatives.
// The heuristics will usually prefer a v2 version, if there is one.
// TODO: It does not take advantage of hints provided by the user:
// 1. syntactic context: pkg.Name().Foo
// 3. already imported files in the same module
func (s *goplsSource) ResolveReferences(ctx context.Context, filename string, missing imports.References) ([]*imports.Result, error) {
	s.ctx = ctx
	// get results from the workspace. There will at most one for each package name
	fromWS, err := s.resolveWorkspaceReferences(filename, missing)
	if err != nil {
		return nil, err
	}
	// collect the ones that are still
	needed := maps.Clone(missing)
	for _, a := range fromWS {
		delete(needed, a.Package.Name)
	}
	// when debug (below) is gone, change this to: if len(needed) == 0 {return fromWS, nil}
	var fromCache []*result
	if len(needed) != 0 {
		var err error
		fromCache, err = s.resolveCacheReferences(needed)
		if err != nil {
			return nil, err
		}
		// trim candidates to one per missing package.
		byPkgNm := make(map[string][]*result)
		for _, c := range fromCache {
			// avoid internal and vendor
			if !imports.CanUse(filename, c.res.Import.ImportPath) {
				continue
			}
			byPkgNm[c.res.Package.Name] = append(byPkgNm[c.res.Package.Name], c)
		}
		for k, v := range byPkgNm {
			fromWS = append(fromWS, s.bestCache(k, v))
		}
	}
	const debug = false
	if debug { // debugging.
		// what does the old one find?
		old, err := s.envSource.ResolveReferences(ctx, filename, missing)
		if err != nil {
			log.Fatal(err)
		}
		log.Printf("fromCache:%d %s", len(fromCache), filename)
		for i, c := range fromCache {
			log.Printf("cans%d %#v %#v %v", i, c.res.Import, c.res.Package, c.deprecated)
		}
		for k, v := range missing {
			for x := range v {
				log.Printf("missing %s.%s", k, x)
			}
		}
		for k, v := range needed {
			for x := range v {
				log.Printf("needed %s.%s", k, x)
			}
		}

		dbgpr := func(hdr string, v []*imports.Result) {
			for i := range v {
				log.Printf("%s%d %+v %+v", hdr, i, v[i].Import, v[i].Package)
			}
		}

		dbgpr("fromWS", fromWS)
		dbgpr("old", old)
		for k, v := range s.snapshot.workspacePackages.All() {
			log.Printf("workspacePackages[%s]=%s", k, v)
		}
		// anything in ans with >1 matches?
		seen := make(map[string]int)
		for _, a := range fromWS {
			seen[a.Package.Name]++
		}
		for k, v := range seen {
			if v > 1 {
				log.Printf("saw %d %s", v, k)
				for i, x := range fromWS {
					if x.Package.Name == k {
						log.Printf("%d: %+v %+v", i, x.Package, x.Import)
					}
				}
			}
		}
	}
	return fromWS, nil

}

func (s *goplsSource) resolveCacheReferences(missing imports.References) ([]*result, error) {
	ix, err := s.snapshot.view.ModcacheIndex()
	if err != nil {
		return nil, err
	}

	found := make(map[string]*result)
	for pkgName, nameSet := range missing {
		names := moremaps.KeySlice(nameSet)
		for importPath, cands := range ix.LookupAll(pkgName, names...) {
			res := found[importPath]
			if res == nil {
				res = &result{
					res: &imports.Result{
						Import: &imports.ImportInfo{
							ImportPath: importPath,
						},
						Package: &imports.PackageInfo{
							Name:    pkgName,
							Exports: make(map[string]bool)},
					},
					deprecated: false,
				}
				found[importPath] = res
			}
			for _, c := range cands {
				res.res.Package.Exports[c.Name] = true
				// The import path is deprecated if a symbol that would be used is deprecated
				res.deprecated = res.deprecated || c.Deprecated
			}
		}

	}
	// return results in some deterministic order
	got := moremaps.ValueSlice(found)
	slices.SortFunc(got, func(a, b *result) int {
		return strings.Compare(a.res.Import.ImportPath, b.res.Import.ImportPath)
	})
	return got, nil
}

type found struct {
	sym *symbols.Package
	res *imports.Result
}

func (s *goplsSource) resolveWorkspaceReferences(filename string, missing imports.References) ([]*imports.Result, error) {
	uri := protocol.URIFromPath(filename)
	mypkgs, err := s.snapshot.MetadataForFile(s.ctx, uri, false)
	if err != nil {
		return nil, err
	}
	if len(mypkgs) == 0 {
		return nil, nil
	}
	mypkg := mypkgs[0] // narrowest package
	// search the metadata graph for package ids corresponding to missing
	g := s.snapshot.MetadataGraph()
	var ids []metadata.PackageID
	var pkgs []*metadata.Package
	for pid, pkg := range g.Packages {
		// no test packages, except perhaps for ourselves
		if pkg.ForTest != "" && pkg != mypkg {
			continue
		}
		if missingWants(missing, pkg.Name) {
			ids = append(ids, pid)
			pkgs = append(pkgs, pkg)
		}
	}
	// find the symbols in those packages
	// the syms occur in the same order as the ids and the pkgs
	syms, err := s.snapshot.Symbols(s.ctx, ids...)
	if err != nil {
		return nil, err
	}
	// keep track of used syms and found results by package name
	// TODO: avoid import cycles (is current package in forward closure)
	founds := make(map[string][]found)
	for i := range len(ids) {
		nm := string(pkgs[i].Name)
		if satisfies(syms[i], missing[nm]) {
			got := &imports.Result{
				Import: &imports.ImportInfo{
					Name:       "",
					ImportPath: string(pkgs[i].PkgPath),
				},
				Package: &imports.PackageInfo{
					Name:    string(pkgs[i].Name),
					Exports: missing[imports.PackageName(pkgs[i].Name)],
				},
			}
			founds[nm] = append(founds[nm], found{syms[i], got})
		}
	}
	var ans []*imports.Result
	for _, v := range founds {
		// make sure the elements of v are unique
		// (Import.ImportPath or Package.Name must differ)
		cmp := func(l, r found) int {
			switch strings.Compare(l.res.Import.ImportPath, r.res.Import.ImportPath) {
			case -1:
				return -1
			case 1:
				return 1
			}
			return strings.Compare(l.res.Package.Name, r.res.Package.Name)
		}
		slices.SortFunc(v, cmp)
		newv := make([]found, 0, len(v))
		newv = append(newv, v[0])
		for i := 1; i < len(v); i++ {
			if cmp(v[i], v[i-1]) != 0 {
				newv = append(newv, v[i])
			}
		}
		ans = append(ans, bestImport(filename, newv))
	}
	return ans, nil
}

// for each package name, choose one using heuristics
func bestImport(filename string, got []found) *imports.Result {
	if len(got) == 1 {
		return got[0].res
	}
	isTestFile := strings.HasSuffix(filename, "_test.go")
	var leftovers []found
	for _, g := range got {
		// don't use _test packages unless isTestFile
		testPkg := strings.HasSuffix(string(g.res.Package.Name), "_test") || strings.HasSuffix(string(g.res.Import.Name), "_test")
		if testPkg && !isTestFile {
			continue // no test covers this
		}
		if imports.CanUse(filename, g.sym.Files[0].DirPath()) {
			leftovers = append(leftovers, g)
		}
	}
	switch len(leftovers) {
	case 0:
		break // use got, they are all bad
	case 1:
		return leftovers[0].res // only one left
	default:
		got = leftovers // filtered some out
	}

	// TODO: if there are versions (like /v2) prefer them

	// use distance to common ancestor with filename
	// (TestDirectoryFilters_MultiRootImportScanning)
	// filename is .../a/main.go, choices are
	// .../a/hi/hi.go and .../b/hi/hi.go
	longest := -1
	ix := -1
	for i := 0; i < len(got); i++ {
		d := commonpref(filename, got[i].sym.Files[0].Path())
		if d > longest {
			longest = d
			ix = i
		}
	}
	// it is possible that there were several tied, but we return the first
	return got[ix].res
}

// choose the best result for the package named nm from the module cache
func (s *goplsSource) bestCache(nm string, got []*result) *imports.Result {
	if len(got) == 1 {
		return got[0].res
	}
	// does the go.mod file choose one?
	if ans := s.fromGoMod(got); ans != nil {
		return ans
	}
	got = preferUndeprecated(got)
	// want the best Import.ImportPath
	// these are all for the package named nm,
	// nm (probably) occurs in all the paths;
	// choose the longest (after nm), so as to get /v2
	maxlen, which := -1, -1
	for i := 0; i < len(got); i++ {
		ix := strings.Index(got[i].res.Import.ImportPath, nm)
		if ix == -1 {
			continue // now what?
		}
		cnt := len(got[i].res.Import.ImportPath) - ix
		if cnt > maxlen {
			maxlen = cnt
			which = i
		}
		// what about ties? (e.g., /v2 and /v3)
	}
	if which >= 0 {
		return got[which].res
	}
	return got[0].res // arbitrary guess
}

// if go.mod requires one of the packages, return that
func (s *goplsSource) fromGoMod(got []*result) *imports.Result {
	// should we use s.S.view.worsspaceModFiles, and the union of their requires?
	// (note that there are no tests where it contains more than one)
	modURI := s.snapshot.view.gomod
	modfh, ok := s.snapshot.files.get(modURI)
	if !ok {
		return nil
	}
	parsed, err := s.snapshot.ParseMod(s.ctx, modfh)
	if err != nil {
		return nil
	}
	reqs := parsed.File.Require
	for _, g := range got {
		for _, req := range reqs {
			if strings.HasPrefix(g.res.Import.ImportPath, req.Syntax.Token[1]) {
				return g.res
			}
		}
	}
	return nil
}

func commonpref(filename string, path string) int {
	k := 0
	for ; k < len(filename) && k < len(path) && filename[k] == path[k]; k++ {
	}
	return k
}

func satisfies(pkg *symbols.Package, missing map[string]bool) bool {
	syms := make(map[string]bool)
	for _, x := range pkg.Symbols {
		for _, s := range x {
			syms[s.Name] = true
		}
	}
	for k := range missing {
		if !syms[k] {
			return false
		}
	}
	return true
}

// does pkgPath potentially satisfy a missing reference?
func missingWants(missing imports.References, pkgPath metadata.PackageName) bool {
	for k := range missing {
		if string(k) == string(pkgPath) {
			return true
		}
	}
	return false
}

// If there are both deprecated and undprecated ones
// then return only the undeprecated one
func preferUndeprecated(got []*result) []*result {
	var ok []*result
	for _, g := range got {
		if !g.deprecated {
			ok = append(ok, g)
		}
	}
	if len(ok) > 0 {
		return ok
	}
	return got
}


================================================
FILE: gopls/internal/cache/symbols/symbols.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package symbols defines the serializable index of package symbols extracted
// from parsed package files.
package symbols

import (
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/frob"
	"golang.org/x/tools/internal/astutil"
)

// Symbol holds a precomputed symbol value. This is a subset of the information
// in the full protocol.SymbolInformation struct to reduce the size of each
// symbol.
type Symbol struct {
	Name  string
	Kind  protocol.SymbolKind
	Range protocol.Range
}

// A Package holds information about symbols declared by each file of a
// package.
//
// The symbols included are: package-level declarations, and fields and methods
// of type declarations.
type Package struct {
	Files   []protocol.DocumentURI // package files
	Symbols [][]Symbol             // symbols in each file
}

var codec = frob.CodecFor[Package]()

// Decode decodes data from [Package.Encode].
func Decode(data []byte) *Package {
	var pkg Package
	codec.Decode(data, &pkg)
	return &pkg
}

// Encode encodes the package.
func (pkg *Package) Encode() []byte {
	return codec.Encode(*pkg)
}

// New returns a new [Package] summarizing symbols in the given files.
func New(files []*parsego.File) *Package {
	var (
		uris    []protocol.DocumentURI
		symbols [][]Symbol
	)
	for _, pgf := range files {
		uris = append(uris, pgf.URI)
		syms := symbolizeFile(pgf)
		symbols = append(symbols, syms)
	}
	return &Package{
		Files:   uris,
		Symbols: symbols,
	}
}

// symbolizeFile reads and parses a file and extracts symbols from it.
func symbolizeFile(pgf *parsego.File) []Symbol {
	w := &symbolWalker{
		nodeRange: pgf.NodeRange,
	}

	for _, decl := range pgf.File.Decls {
		switch decl := decl.(type) {
		case *ast.FuncDecl:
			kind := protocol.Function
			var recv *ast.Ident
			if decl.Recv.NumFields() > 0 {
				kind = protocol.Method
				_, recv, _ = astutil.UnpackRecv(decl.Recv.List[0].Type)
			}
			w.declare(decl.Name.Name, kind, decl.Name, recv)

		case *ast.GenDecl:
			for _, spec := range decl.Specs {
				switch spec := spec.(type) {
				case *ast.TypeSpec:
					kind := protocol.Class
					switch spec.Type.(type) {
					case *ast.InterfaceType:
						kind = protocol.Interface
					case *ast.StructType:
						kind = protocol.Struct
					case *ast.FuncType:
						kind = protocol.Function
					}
					w.declare(spec.Name.Name, kind, spec.Name)
					w.walkType(spec.Type, spec.Name)
				case *ast.ValueSpec:
					for _, name := range spec.Names {
						kind := protocol.Variable
						if decl.Tok == token.CONST {
							kind = protocol.Constant
						}
						w.declare(name.Name, kind, name)
					}
				}
			}
		}
	}

	return w.symbols
}

type symbolWalker struct {
	nodeRange func(node ast.Node) (protocol.Range, error) // for computing positions

	symbols []Symbol
}

// declare declares a symbol of the specified name, kind, node location, and enclosing dotted path of identifiers.
func (w *symbolWalker) declare(name string, kind protocol.SymbolKind, node ast.Node, path ...*ast.Ident) {
	var b strings.Builder
	for _, ident := range path {
		if ident != nil {
			b.WriteString(ident.Name)
			b.WriteString(".")
		}
	}
	b.WriteString(name)

	rng, err := w.nodeRange(node)
	if err != nil {
		// TODO(rfindley): establish an invariant that node positions cannot exceed
		// the file. This is not currently the case--for example see
		// golang/go#48300 (this can also happen due to phantom selectors).
		//
		// For now, we have nothing to do with this error.
		return
	}
	sym := Symbol{
		Name:  b.String(),
		Kind:  kind,
		Range: rng,
	}
	w.symbols = append(w.symbols, sym)
}

// walkType processes symbols related to a type expression. path is path of
// nested type identifiers to the type expression.
func (w *symbolWalker) walkType(typ ast.Expr, path ...*ast.Ident) {
	switch st := typ.(type) {
	case *ast.StructType:
		for _, field := range st.Fields.List {
			w.walkField(field, protocol.Field, protocol.Field, path...)
		}
	case *ast.InterfaceType:
		for _, field := range st.Methods.List {
			w.walkField(field, protocol.Interface, protocol.Method, path...)
		}
	}
}

// walkField processes symbols related to the struct field or interface method.
//
// unnamedKind and namedKind are the symbol kinds if the field is resp. unnamed
// or named. path is the path of nested identifiers containing the field.
func (w *symbolWalker) walkField(field *ast.Field, unnamedKind, namedKind protocol.SymbolKind, path ...*ast.Ident) {
	if len(field.Names) == 0 {
		switch typ := field.Type.(type) {
		case *ast.SelectorExpr:
			// embedded qualified type
			w.declare(typ.Sel.Name, unnamedKind, field, path...)
		default:
			w.declare(types.ExprString(field.Type), unnamedKind, field, path...)
		}
	}
	for _, name := range field.Names {
		w.declare(name.Name, namedKind, name, path...)
		w.walkType(field.Type, append(path, name)...)
	}
}


================================================
FILE: gopls/internal/cache/symbols.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"crypto/sha256"
	"fmt"
	"go/parser"
	"go/token"
	"runtime"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/symbols"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/event"
)

// Symbols extracts and returns symbol information for every file contained in
// a loaded package. It awaits snapshot loading.
//
// If workspaceOnly is set, this only includes symbols from files in a
// workspace package. Otherwise, it returns symbols from all loaded packages.
func (s *Snapshot) Symbols(ctx context.Context, ids ...PackageID) ([]*symbols.Package, error) {
	meta := s.MetadataGraph()

	res := make([]*symbols.Package, len(ids))
	var g errgroup.Group
	g.SetLimit(runtime.GOMAXPROCS(-1)) // symbolizing is cpu bound
	for i, id := range ids {
		g.Go(func() error {
			mp := meta.Packages[id]
			if mp == nil {
				return bug.Errorf("missing metadata for %q", id)
			}

			key, fhs, err := symbolKey(ctx, mp, s)
			if err != nil {
				return err
			}

			if data, err := filecache.Get(symbolsKind, key); err == nil {
				res[i] = symbols.Decode(data)
				return nil
			} else if err != filecache.ErrNotFound {
				bug.Reportf("internal error reading symbol data: %v", err)
			}

			pgfs, err := s.view.parseCache.parseFiles(ctx, token.NewFileSet(), parsego.Full&^parser.ParseComments, false, fhs...)
			if err != nil {
				return err
			}
			pkg := symbols.New(pgfs)

			// Store the resulting data in the cache.
			go func() {
				data := pkg.Encode()
				if err := filecache.Set(symbolsKind, key, data); err != nil {
					event.Error(ctx, fmt.Sprintf("storing symbol data for %s", id), err)
				}
			}()

			res[i] = pkg
			return nil
		})
	}

	return res, g.Wait()
}

func symbolKey(ctx context.Context, mp *metadata.Package, fs file.Source) (file.Hash, []file.Handle, error) {
	seen := make(map[protocol.DocumentURI]bool)
	var fhs []file.Handle
	for _, list := range [][]protocol.DocumentURI{mp.GoFiles, mp.CompiledGoFiles} {
		for _, uri := range list {
			if !seen[uri] {
				seen[uri] = true
				fh, err := fs.ReadFile(ctx, uri)
				if err != nil {
					return file.Hash{}, nil, err // context cancelled
				}
				fhs = append(fhs, fh)
			}
		}
	}

	hasher := sha256.New()
	fmt.Fprintf(hasher, "symbols: %s\n", mp.PkgPath)
	fmt.Fprintf(hasher, "files: %d\n", len(fhs))
	for _, fh := range fhs {
		fmt.Fprintln(hasher, fh.Identity())
	}
	var hash file.Hash
	hasher.Sum(hash[:0])
	return hash, fhs, nil
}


================================================
FILE: gopls/internal/cache/testfuncs/match.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testfuncs

import (
	"fmt"
	"strconv"
	"strings"
)

// The functions in this file are copies of those from the testing package.
//
// https://cs.opensource.google/go/go/+/refs/tags/go1.22.5:src/testing/match.go

// uniqueName creates a unique name for the given parent and subname by affixing
// it with one or more counts, if necessary.
func (b *indexBuilder) uniqueName(parent, subname string) string {
	base := parent + "/" + subname

	for {
		n := b.subNames[base]
		if n < 0 {
			panic("subtest count overflow")
		}
		b.subNames[base] = n + 1

		if n == 0 && subname != "" {
			prefix, nn := parseSubtestNumber(base)
			if len(prefix) < len(base) && nn < b.subNames[prefix] {
				// This test is explicitly named like "parent/subname#NN",
				// and #NN was already used for the NNth occurrence of "parent/subname".
				// Loop to add a disambiguating suffix.
				continue
			}
			return base
		}

		name := fmt.Sprintf("%s#%02d", base, n)
		if b.subNames[name] != 0 {
			// This is the nth occurrence of base, but the name "parent/subname#NN"
			// collides with the first occurrence of a subtest *explicitly* named
			// "parent/subname#NN". Try the next number.
			continue
		}

		return name
	}
}

// parseSubtestNumber splits a subtest name into a "#%02d"-formatted int
// suffix (if present), and a prefix preceding that suffix (always).
func parseSubtestNumber(s string) (prefix string, nn int) {
	i := strings.LastIndex(s, "#")
	if i < 0 {
		return s, 0
	}

	prefix, suffix := s[:i], s[i+1:]
	if len(suffix) < 2 || (len(suffix) > 2 && suffix[0] == '0') {
		// Even if suffix is numeric, it is not a possible output of a "%02" format
		// string: it has either too few digits or too many leading zeroes.
		return s, 0
	}
	if suffix == "00" {
		if !strings.HasSuffix(prefix, "/") {
			// We only use "#00" as a suffix for subtests named with the empty
			// string — it isn't a valid suffix if the subtest name is non-empty.
			return s, 0
		}
	}

	n, err := strconv.ParseInt(suffix, 10, 32)
	if err != nil || n < 0 {
		return s, 0
	}
	return prefix, int(n)
}

// rewrite rewrites a subname to having only printable characters and no white
// space.
func rewrite(s string) string {
	b := []byte{}
	for _, r := range s {
		switch {
		case isSpace(r):
			b = append(b, '_')
		case !strconv.IsPrint(r):
			s := strconv.QuoteRune(r)
			b = append(b, s[1:len(s)-1]...)
		default:
			b = append(b, string(r)...)
		}
	}
	return string(b)
}

func isSpace(r rune) bool {
	if r < 0x2000 {
		switch r {
		// Note: not the same as Unicode Z class.
		case '\t', '\n', '\v', '\f', '\r', ' ', 0x85, 0xA0, 0x1680:
			return true
		}
	} else {
		if r <= 0x200a {
			return true
		}
		switch r {
		case 0x2028, 0x2029, 0x202f, 0x205f, 0x3000:
			return true
		}
	}
	return false
}


================================================
FILE: gopls/internal/cache/testfuncs/tests.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testfuncs

import (
	"go/ast"
	"go/constant"
	"go/types"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/frob"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// An Index records the test set of a package.
type Index struct {
	pkg gobPackage
}

// Decode decodes the given gob-encoded data as an Index.
func Decode(data []byte) *Index {
	var pkg gobPackage
	packageCodec.Decode(data, &pkg)
	return &Index{pkg}
}

// Encode encodes the receiver as gob-encoded data.
func (index *Index) Encode() []byte {
	return packageCodec.Encode(index.pkg)
}

func (index *Index) All() []Result {
	var results []Result
	for _, file := range index.pkg.Files {
		for _, test := range file.Tests {
			results = append(results, test.result())
		}
	}
	return results
}

// A Result reports a test function
type Result struct {
	Location protocol.Location // location of the test
	Name     string            // name of the test
}

// NewIndex returns a new index of method-set information for all
// package-level types in the specified package.
func NewIndex(files []*parsego.File, info *types.Info) *Index {
	b := &indexBuilder{
		fileIndex: make(map[protocol.DocumentURI]int),
		subNames:  make(map[string]int),
		visited:   make(map[*types.Func]bool),
	}
	return b.build(files, info)
}

// build adds to the index all tests of the specified package.
func (b *indexBuilder) build(files []*parsego.File, info *types.Info) *Index {
	for _, file := range files {
		if !strings.HasSuffix(file.Tok.Name(), "_test.go") {
			continue
		}

		for _, decl := range file.File.Decls {
			decl, ok := decl.(*ast.FuncDecl)
			if !ok {
				continue
			}
			obj, ok := info.ObjectOf(decl.Name).(*types.Func)
			if !ok || !obj.Exported() {
				continue
			}

			// error.Error has empty Position, PkgPath, and ObjectPath.
			if obj.Pkg() == nil {
				continue
			}

			isTest, isExample := isTestOrExample(obj)
			if !isTest && !isExample {
				continue
			}

			var t gobTest
			t.Name = decl.Name.Name
			t.Location.URI = file.URI
			t.Location.Range, _ = file.NodeRange(decl)

			i, ok := b.fileIndex[t.Location.URI]
			if !ok {
				i = len(b.Files)
				b.Files = append(b.Files, gobFile{})
				b.fileIndex[t.Location.URI] = i
			}

			b.Files[i].Tests = append(b.Files[i].Tests, t)
			b.visited[obj] = true

			// Check for subtests
			if isTest {
				b.Files[i].Tests = append(b.Files[i].Tests, b.findSubtests(t, decl.Type, decl.Body, file, files, info)...)
			}
		}
	}

	return &Index{pkg: b.gobPackage}
}

func (b *indexBuilder) findSubtests(parent gobTest, typ *ast.FuncType, body *ast.BlockStmt, file *parsego.File, files []*parsego.File, info *types.Info) []gobTest {
	if body == nil {
		return nil
	}

	// If the [testing.T] parameter is unnamed, the func cannot call
	// [testing.T.Run] and thus cannot create any subtests
	if len(typ.Params.List[0].Names) == 0 {
		return nil
	}

	// This "can't fail" because testKind should guarantee that the function has
	// one parameter and the check above guarantees that parameter is named
	param := info.ObjectOf(typ.Params.List[0].Names[0])

	// Find statements of form t.Run(name, func(...) {...}) where t is the
	// parameter of the enclosing test function.
	var tests []gobTest
	for _, stmt := range body.List {
		expr, ok := stmt.(*ast.ExprStmt)
		if !ok {
			continue
		}

		call, ok := expr.X.(*ast.CallExpr)
		if !ok || len(call.Args) != 2 {
			continue
		}
		fun, ok := call.Fun.(*ast.SelectorExpr)
		if !ok || fun.Sel.Name != "Run" {
			continue
		}
		recv, ok := fun.X.(*ast.Ident)
		if !ok || info.ObjectOf(recv) != param {
			continue
		}

		sig, ok := info.TypeOf(call.Args[1]).(*types.Signature)
		if !ok {
			continue
		}
		if _, ok := testKind(sig); !ok {
			continue // subtest has wrong signature
		}

		val := info.Types[call.Args[0]].Value // may be zero
		if val == nil || val.Kind() != constant.String {
			continue
		}

		var t gobTest
		t.Name = b.uniqueName(parent.Name, rewrite(constant.StringVal(val)))
		t.Location.URI = file.URI
		t.Location.Range, _ = file.NodeRange(call)
		tests = append(tests, t)

		fn, typ, body := findFunc(files, info, body, call.Args[1])
		if typ == nil {
			continue
		}

		// Function literals don't have an associated object
		if fn == nil {
			tests = append(tests, b.findSubtests(t, typ, body, file, files, info)...)
			continue
		}

		// Never recurse if the second argument is a top-level test function
		if isTest, _ := isTestOrExample(fn); isTest {
			continue
		}

		// Don't recurse into functions that have already been visited
		if b.visited[fn] {
			continue
		}

		b.visited[fn] = true
		tests = append(tests, b.findSubtests(t, typ, body, file, files, info)...)
	}
	return tests
}

// findFunc finds the type and body of the given expr, which may be a function
// literal or reference to a declared function. If the expression is a declared
// function, findFunc returns its [types.Func]. If the expression is a function
// literal, findFunc returns nil for the first return value. If no function is
// found, findFunc returns (nil, nil, nil).
func findFunc(files []*parsego.File, info *types.Info, body *ast.BlockStmt, expr ast.Expr) (*types.Func, *ast.FuncType, *ast.BlockStmt) {
	var obj types.Object
	switch arg := expr.(type) {
	case *ast.FuncLit:
		return nil, arg.Type, arg.Body

	case *ast.Ident:
		obj = info.ObjectOf(arg)
		if obj == nil {
			return nil, nil, nil
		}

	case *ast.SelectorExpr:
		// Look for methods within the current package. We will not handle
		// imported functions and methods for now, as that would require access
		// to the source of other packages and would be substantially more
		// complex. However, those cases should be rare.
		sel, ok := info.Selections[arg]
		if !ok {
			return nil, nil, nil
		}
		obj = sel.Obj()

	default:
		return nil, nil, nil
	}

	if v, ok := obj.(*types.Var); ok {
		// TODO: Handle vars. This could handled by walking over the body (and
		// the file), but that doesn't account for assignment. If the variable
		// is assigned multiple times, we could easily get the wrong one.
		_, _ = v, body
		return nil, nil, nil
	}

	for _, file := range files {
		// Skip files that don't contain the object (there should only be a
		// single file that _does_ contain it)
		if _, err := safetoken.Offset(file.Tok, obj.Pos()); err != nil {
			continue
		}

		for _, decl := range file.File.Decls {
			decl, ok := decl.(*ast.FuncDecl)
			if !ok {
				continue
			}

			if info.ObjectOf(decl.Name) == obj {
				return obj.(*types.Func), decl.Type, decl.Body
			}
		}
	}
	return nil, nil, nil
}

// isTestOrExample reports whether the given func is a testing func or an
// example func (or neither). isTestOrExample returns (true, false) for testing
// funcs, (false, true) for example funcs, and (false, false) otherwise.
func isTestOrExample(fn *types.Func) (isTest, isExample bool) {
	sig := fn.Type().(*types.Signature)
	if sig.Params().Len() == 0 &&
		sig.Results().Len() == 0 {
		return false, isTestName(fn.Name(), "Example")
	}

	kind, ok := testKind(sig)
	if !ok {
		return false, false
	}
	switch kind.Name() {
	case "T":
		return isTestName(fn.Name(), "Test"), false
	case "B":
		return isTestName(fn.Name(), "Benchmark"), false
	case "F":
		return isTestName(fn.Name(), "Fuzz"), false
	default:
		return false, false // "can't happen" (see testKind)
	}
}

// isTestName reports whether name is a valid test name for the test kind
// indicated by the given prefix ("Test", "Benchmark", etc.).
//
// Adapted from go/analysis/passes/tests.
func isTestName(name, prefix string) bool {
	suffix, ok := strings.CutPrefix(name, prefix)
	if !ok {
		return false
	}
	if len(suffix) == 0 {
		// "Test" is ok.
		return true
	}
	r, _ := utf8.DecodeRuneInString(suffix)
	return !unicode.IsLower(r)
}

// testKind returns the parameter type TypeName of a test, benchmark, or fuzz
// function (one of testing.[TBF]).
func testKind(sig *types.Signature) (*types.TypeName, bool) {
	if sig.Params().Len() != 1 ||
		sig.Results().Len() != 0 {
		return nil, false
	}

	ptr, ok := sig.Params().At(0).Type().(*types.Pointer)
	if !ok {
		return nil, false
	}

	named, ok := ptr.Elem().(*types.Named)
	if !ok || named.Obj().Pkg() == nil || named.Obj().Pkg().Path() != "testing" {
		return nil, false
	}

	switch named.Obj().Name() {
	case "T", "B", "F":
		return named.Obj(), true
	}
	return nil, false
}

// An indexBuilder builds an index for a single package.
type indexBuilder struct {
	gobPackage
	fileIndex map[protocol.DocumentURI]int
	subNames  map[string]int
	visited   map[*types.Func]bool
}

// -- serial format of index --

// (The name says gob but in fact we use frob.)
var packageCodec = frob.CodecFor[gobPackage]()

// A gobPackage records the test set of each package-level type for a single package.
type gobPackage struct {
	Files []gobFile
}

type gobFile struct {
	Tests []gobTest
}

// A gobTest records the name, type, and position of a single test.
type gobTest struct {
	Location protocol.Location // location of the test
	Name     string            // name of the test
}

func (t *gobTest) result() Result {
	return Result(*t)
}


================================================
FILE: gopls/internal/cache/typerefs/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typerefs extracts symbol-level reachability information
// from the syntax of a Go package.
//
// # Background
//
// The goal of this analysis is to determine, for each package P, a nearly
// minimal set of packages that could affect the type checking of P. This set
// may contain false positives, but the smaller this set the better we can
// invalidate and prune packages in gopls.
//
// More precisely, for each package P we define the set of "reachable" packages
// from P as the set of packages that may affect the (deep) export data of the
// direct dependencies of P. By this definition, the complement of this set
// cannot affect any information derived from type checking P, such as
// diagnostics, cross references, or method sets. Therefore we need not
// invalidate any results for P when a package in the complement of this set
// changes.
//
// # Computing references
//
// For a given declaration D, references are computed based on identifiers or
// dotted identifiers referenced in the declaration of D, that may affect
// the type of D. However, these references reflect only local knowledge of the
// package and its dependency metadata, and do not depend on any analysis of
// the dependencies themselves. This allows the reference information for
// a package to be cached independent of all others.
//
// Specifically, if a referring identifier I appears in the declaration, we
// record an edge from D to each object possibly referenced by I. We search for
// references within type syntax, but do not actually type-check, so we can't
// reliably determine whether an expression is a type or a term, or whether a
// function is a builtin or generic. For example, the type of x in var x =
// p.F(W) only depends on W if p.F is a builtin or generic function, which we
// cannot know without type-checking package p. So we may over-approximate in
// this way.
//
//   - If I is declared in the current package, record a reference to its
//     declaration.
//   - Otherwise, if there are any dot imports in the current
//     file and I is exported, record a (possibly dangling) edge to
//     the corresponding declaration in each dot-imported package.
//
// If a dotted identifier q.I appears in the declaration, we
// perform a similar operation:
//
//   - If q is declared in the current package, we record a reference to that
//     object. It may be a var or const that has a field or method I.
//   - Otherwise, if q is a valid import name based on imports in the current file
//     and the provided metadata for dependency package names, record a
//     reference to the object I in that package.
//   - Additionally, handle the case where Q is exported, and Q.I may refer to
//     a field or method in a dot-imported package.
//
// That is essentially the entire algorithm, though there is some subtlety to
// visiting the set of identifiers or dotted identifiers that may affect the
// declaration type. See the visitDeclOrSpec function for the details of this
// analysis. Notably, we also skip identifiers that refer to type parameters in
// generic declarations.
//
// # Graph optimizations
//
// The references extracted from the syntax are used to construct
// edges between nodes representing declarations. Edges are of two
// kinds: internal references, from one package-level declaration to
// another; and external references, from a symbol in this package to
// a symbol imported from a direct dependency.
//
// Once the symbol reference graph is constructed, we find its
// strongly connected components (SCCs) using Tarjan's algorithm.
// As we coalesce the nodes of each SCC we compute the union of
// external references reached by each package-level declaration.
// The final result is the mapping from each exported package-level
// declaration to the set of external (imported) declarations that it
// reaches.
//
// Because it is common for many package members to have the same
// reachability, the result takes the form of a set of equivalence
// classes, each mapping a set of package-level declarations to a set
// of external symbols. We use a hash table to canonicalize sets so that
// repeated occurrences of the same set (which are common) are only
// represented once in memory or in the file system.
// For example, all declarations that ultimately reference only
// {fmt.Println,strings.Join} would be classed as equivalent.
//
// This approach was inspired by the Hash-Value Numbering (HVN)
// optimization described by Hardekopf and Lin. See
// golang.org/x/tools/go/pointer/hvn.go for an implementation. (Like
// pointer analysis, this problem is fundamentally one of graph
// reachability.) The HVN algorithm takes the compression a step
// further by preserving the topology of the SCC DAG, in which edges
// represent "is a superset of" constraints. Redundant edges that
// don't increase the solution can be deleted. We could apply the same
// technique here to further reduce the worst-case size of the result,
// but the current implementation seems adequate.
//
// # API
//
// The main entry point for this analysis is the [Encode] function,
// which implements the analysis described above for one package, and
// encodes the result as a binary message.
//
// The [Decode] function decodes the message into a usable form: a set
// of equivalence classes. The decoder uses a shared [PackageIndex] to
// enable more compact representations of sets of packages
// ([PackageSet]) during the global reacahability computation.
//
// The [BuildPackageGraph] constructor implements a whole-graph analysis similar
// to that which will be implemented by gopls, but for various reasons the
// logic for this analysis will eventually live in the
// [golang.org/x/tools/gopls/internal/cache] package. Nevertheless,
// BuildPackageGraph and its test serve to verify the syntactic analysis, and
// may serve as a proving ground for new optimizations of the whole-graph analysis.
//
// # Export data is insufficient
//
// At first it may seem that the simplest way to implement this analysis would
// be to consider the types.Packages of the dependencies of P, for example
// during export. After all, it makes sense that the type checked packages
// themselves could describe their dependencies. However, this does not work as
// type information does not describe certain syntactic relationships.
//
// For example, the following scenarios cause type information to miss
// syntactic relationships:
//
// Named type forwarding:
//
//	package a; type A b.B
//	package b; type B int
//
// Aliases:
//
//	package a; func A(f b.B)
//	package b; type B = func()
//
// Initializers:
//
//	package a; var A = b.B()
//	package b; func B() string { return "hi" }
//
// Use of the unsafe package:
//
//	package a; type A [unsafe.Sizeof(B{})]int
//	package b; type B struct { f1, f2, f3 int }
//
// In all of these examples, types do not contain information about the edge
// between the a.A and b.B declarations.
package typerefs


================================================
FILE: gopls/internal/cache/typerefs/packageset.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typerefs

import (
	"fmt"
	"math/bits"
	"strings"
	"sync"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/util/moremaps"
)

// PackageIndex stores common data to enable efficient representation of
// references and package sets.
type PackageIndex struct {
	// For now, PackageIndex just indexes package ids, to save space and allow for
	// faster unions via sparse int vectors.
	mu  sync.Mutex
	ids []metadata.PackageID
	m   map[metadata.PackageID]IndexID
}

// NewPackageIndex creates a new PackageIndex instance for use in building
// reference and package sets.
func NewPackageIndex() *PackageIndex {
	return &PackageIndex{
		m: make(map[metadata.PackageID]IndexID),
	}
}

// IndexID returns the packageIdx referencing id, creating one if id is not yet
// tracked by the receiver.
func (index *PackageIndex) IndexID(id metadata.PackageID) IndexID {
	index.mu.Lock()
	defer index.mu.Unlock()
	if i, ok := index.m[id]; ok {
		return i
	}
	i := IndexID(len(index.ids))
	index.m[id] = i
	index.ids = append(index.ids, id)
	return i
}

// PackageID returns the PackageID for idx.
//
// idx must have been created by this PackageIndex instance.
func (index *PackageIndex) PackageID(idx IndexID) metadata.PackageID {
	index.mu.Lock()
	defer index.mu.Unlock()
	return index.ids[idx]
}

// A PackageSet is a set of metadata.PackageIDs, optimized for inuse memory
// footprint and efficient union operations.
type PackageSet struct {
	// PackageSet is a sparse int vector of package indexes from parent.
	parent *PackageIndex
	sparse map[int]blockType // high bits in key, set of low bits in value
}

type blockType = uint // type of each sparse vector element
const blockSize = bits.UintSize

// NewSet creates a new PackageSet bound to this PackageIndex instance.
//
// PackageSets may only be combined with other PackageSets from the same
// instance.
func (index *PackageIndex) NewSet() *PackageSet {
	return &PackageSet{
		parent: index,
		sparse: make(map[int]blockType),
	}
}

// DeclaringPackage returns the ID of the symbol's declaring package.
// The package index must be the one used during decoding.
func (index *PackageIndex) DeclaringPackage(sym Symbol) metadata.PackageID {
	return index.PackageID(sym.Package)
}

// Add records a new element in the package set, for the provided package ID.
func (s *PackageSet) AddPackage(id metadata.PackageID) {
	s.Add(s.parent.IndexID(id))
}

// Add records a new element in the package set.
// It is the caller's responsibility to ensure that idx was created with the
// same PackageIndex as the PackageSet.
func (s *PackageSet) Add(idx IndexID) {
	i := int(idx)
	s.sparse[i/blockSize] |= 1 << (i % blockSize)
}

// Union records all elements from other into the receiver, mutating the
// receiver set but not the argument set. The receiver must not be nil, but the
// argument set may be nil.
//
// Precondition: both package sets were created with the same PackageIndex.
func (s *PackageSet) Union(other *PackageSet) {
	if other == nil {
		return // e.g. unsafe
	}
	if other.parent != s.parent {
		panic("other set is from a different PackageIndex instance")
	}
	for k, v := range other.sparse {
		if v0 := s.sparse[k]; v0 != v {
			s.sparse[k] = v0 | v
		}
	}
}

// Contains reports whether id is contained in the receiver set.
func (s *PackageSet) Contains(id metadata.PackageID) bool {
	i := int(s.parent.IndexID(id))
	return s.sparse[i/blockSize]&(1<<(i%blockSize)) != 0
}

// Elems calls f for each element of the set in ascending order.
func (s *PackageSet) Elems(f func(IndexID)) {
	for i, v := range moremaps.Sorted(s.sparse) {
		for b := range blockSize {
			if (v & (1 << b)) != 0 {
				f(IndexID(i*blockSize + b))
			}
		}
	}
}

// String returns a human-readable representation of the set: {A, B, ...}.
func (s *PackageSet) String() string {
	var ids []string
	s.Elems(func(id IndexID) {
		ids = append(ids, string(s.parent.PackageID(id)))
	})
	return fmt.Sprintf("{%s}", strings.Join(ids, ", "))
}


================================================
FILE: gopls/internal/cache/typerefs/pkggraph_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typerefs_test

// This file is logically part of the test in pkgrefs_test.go: that
// file defines the test assertion logic; this file provides a
// reference implementation of a client of the typerefs package.

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"runtime"
	"sync"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/protocol"
)

const (
	// trace enables additional trace output to stdout, for debugging.
	//
	// Warning: produces a lot of output! Best to run with small package queries.
	trace = false
)

// A Package holds reference information for a single package.
type Package struct {
	// metapkg holds metapkg about this package and its dependencies.
	metapkg *metadata.Package

	// transitiveRefs records, for each exported declaration in the package, the
	// transitive set of packages within the containing graph that are
	// transitively reachable through references, starting with the given decl.
	transitiveRefs map[string]*typerefs.PackageSet

	// ReachesByDeps records the set of packages in the containing graph whose
	// syntax may affect the current package's types. See the package
	// documentation for more details of what this means.
	ReachesByDeps *typerefs.PackageSet
}

// A PackageGraph represents a fully analyzed graph of packages and their
// dependencies.
type PackageGraph struct {
	pkgIndex *typerefs.PackageIndex
	meta     metadata.Source
	parse    func(context.Context, protocol.DocumentURI) (*parsego.File, error)

	mu       sync.Mutex
	packages map[metadata.PackageID]*futurePackage
}

// BuildPackageGraph analyzes the package graph for the requested ids, whose
// metadata is described by meta.
//
// The provided parse function is used to parse the CompiledGoFiles of each package.
//
// The resulting PackageGraph is fully evaluated, and may be investigated using
// the Package method.
//
// See the package documentation for more information on the package reference
// algorithm.
func BuildPackageGraph(ctx context.Context, meta metadata.Source, ids []metadata.PackageID, parse func(context.Context, protocol.DocumentURI) (*parsego.File, error)) (*PackageGraph, error) {
	g := &PackageGraph{
		pkgIndex: typerefs.NewPackageIndex(),
		meta:     meta,
		parse:    parse,
		packages: make(map[metadata.PackageID]*futurePackage),
	}
	metadata.SortPostOrder(meta, ids)

	workers := runtime.GOMAXPROCS(0)
	if trace {
		workers = 1
	}

	var eg errgroup.Group
	eg.SetLimit(workers)
	for _, id := range ids {
		eg.Go(func() error {
			_, err := g.Package(ctx, id)
			return err
		})
	}
	return g, eg.Wait()
}

// futurePackage is a future result of analyzing a package, for use from Package only.
type futurePackage struct {
	done chan struct{}
	pkg  *Package
	err  error
}

// Package gets the result of analyzing references for a single package.
func (g *PackageGraph) Package(ctx context.Context, id metadata.PackageID) (*Package, error) {
	g.mu.Lock()
	fut, ok := g.packages[id]
	if ok {
		g.mu.Unlock()
		select {
		case <-fut.done:
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	} else {
		fut = &futurePackage{done: make(chan struct{})}
		g.packages[id] = fut
		g.mu.Unlock()
		fut.pkg, fut.err = g.buildPackage(ctx, id)
		close(fut.done)
	}
	return fut.pkg, fut.err
}

// buildPackage parses a package and extracts its reference graph. It should
// only be called from Package.
func (g *PackageGraph) buildPackage(ctx context.Context, id metadata.PackageID) (*Package, error) {
	p := &Package{
		metapkg:        g.meta.Metadata(id),
		transitiveRefs: make(map[string]*typerefs.PackageSet),
	}
	var files []*parsego.File
	for _, filename := range p.metapkg.CompiledGoFiles {
		f, err := g.parse(ctx, filename)
		if err != nil {
			return nil, err
		}
		files = append(files, f)
	}
	imports := make(map[metadata.ImportPath]*metadata.Package)
	for impPath, depID := range p.metapkg.DepsByImpPath {
		if depID != "" {
			imports[impPath] = g.meta.Metadata(depID)
		}
	}

	// Compute the symbol-level dependencies through this package.
	data := typerefs.Encode(files, imports)

	// data can be persisted in a filecache, keyed
	// by hash(id, CompiledGoFiles, imports).

	//      This point separates the local preprocessing
	//  --  of a single package (above) from the global   --
	//      transitive reachability query (below).

	// classes records syntactic edges between declarations in this
	// package and declarations in this package or another
	// package. See the package documentation for a detailed
	// description of what these edges do (and do not) represent.
	classes := typerefs.Decode(g.pkgIndex, data)

	// Debug
	if trace && len(classes) > 0 {
		var buf bytes.Buffer
		fmt.Fprintf(&buf, "%s\n", id)
		for _, class := range classes {
			for i, name := range class.Decls {
				if i == 0 {
					fmt.Fprintf(&buf, "\t")
				}
				fmt.Fprintf(&buf, " .%s", name)
			}
			// Group symbols by package.
			var prevID PackageID
			for _, sym := range class.Refs {
				id := g.pkgIndex.DeclaringPackage(sym)
				if id != prevID {
					prevID = id
					fmt.Fprintf(&buf, "\n\t\t-> %s:", id)
				}
				fmt.Fprintf(&buf, " .%s", sym.Name)
			}
			fmt.Fprintln(&buf)
		}
		os.Stderr.Write(buf.Bytes())
	}

	// Now compute the transitive closure of packages reachable
	// from any exported symbol of this package.
	for _, class := range classes {
		set := g.pkgIndex.NewSet()

		// The Refs slice is sorted by (PackageID, name),
		// so we can economize by calling g.Package only
		// when the package id changes.
		depP := p
		for _, sym := range class.Refs {
			symPkgID := g.pkgIndex.DeclaringPackage(sym)
			if symPkgID == id {
				panic("intra-package edge")
			}
			if depP.metapkg.ID != symPkgID {
				// package changed
				var err error
				depP, err = g.Package(ctx, symPkgID)
				if err != nil {
					return nil, err
				}
			}
			set.Add(sym.Package)
			set.Union(depP.transitiveRefs[sym.Name])
		}
		for _, name := range class.Decls {
			p.transitiveRefs[name] = set
		}
	}

	// Finally compute the union of transitiveRefs
	// across the direct deps of this package.
	byDeps, err := g.reachesByDeps(ctx, p.metapkg)
	if err != nil {
		return nil, err
	}
	p.ReachesByDeps = byDeps

	return p, nil
}

// reachesByDeps computes the set of packages that are reachable through
// dependencies of the package m.
func (g *PackageGraph) reachesByDeps(ctx context.Context, mp *metadata.Package) (*typerefs.PackageSet, error) {
	transitive := g.pkgIndex.NewSet()
	for _, depID := range mp.DepsByPkgPath {
		dep, err := g.Package(ctx, depID)
		if err != nil {
			return nil, err
		}
		transitive.AddPackage(dep.metapkg.ID)
		for _, set := range dep.transitiveRefs {
			transitive.Union(set)
		}
	}
	return transitive, nil
}


================================================
FILE: gopls/internal/cache/typerefs/pkgrefs_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typerefs_test

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"go/token"
	"go/types"
	"os"
	"slices"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/testenv"
)

var (
	dir    = flag.String("dir", "", "dir to run go/packages from")
	query  = flag.String("query", "std", "go/packages load query to use for walkdecl tests")
	verify = flag.Bool("verify", true, "whether to verify reachable packages using export data (may be slow on large graphs)")
)

type (
	packageName    = metadata.PackageName
	PackageID      = metadata.PackageID
	ImportPath     = metadata.ImportPath
	PackagePath    = metadata.PackagePath
	Metadata       = metadata.Package
	MetadataSource = metadata.Source
)

// TestBuildPackageGraph tests the BuildPackageGraph constructor, which uses
// the reference analysis of the Refs function to build a graph of
// relationships between packages.
//
// It simulates the operation of gopls at startup: packages are loaded via
// go/packages, and their syntax+metadata analyzed to determine which packages
// are reachable from others.
//
// The test then verifies that the 'load' graph (the graph of relationships in
// export data) is a subgraph of the 'reach' graph constructed by
// BuildPackageGraph. While doing so, it constructs some statistics about the
// relative sizes of these graphs, along with the 'transitive imports' graph,
// to report the effectiveness of the reachability analysis.
//
// The following flags affect this test:
//   - dir sets the dir from which to run go/packages
//   - query sets the go/packages query to load
//   - verify toggles the verification w.r.t. the load graph (which may be
//     prohibitively expensive with large queries).
func TestBuildPackageGraph(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping with -short: loading the packages can take a long time with a cold cache")
	}
	testenv.NeedsGoBuild(t) // for go/packages

	t0 := time.Now()
	exports, meta, err := loadPackages(*query, *verify)
	if err != nil {
		t.Fatalf("loading failed: %v", err)
	}
	t.Logf("loaded %d packages in %v", len(exports), time.Since(t0))

	ctx := context.Background()
	var ids []PackageID
	for id := range exports {
		ids = append(ids, id)
	}
	slices.Sort(ids)

	t0 = time.Now()
	g, err := BuildPackageGraph(ctx, meta, ids, newParser().parse)
	if err != nil {
		t.Fatal(err)
	}
	t.Logf("building package graph took %v", time.Since(t0))

	// Collect information about the edges between packages for later analysis.
	//
	// We compare the following package graphs:
	//  - the imports graph: edges are transitive imports
	//  - the reaches graph: edges are reachability relationships through syntax
	//    of imports (as defined in the package doc)
	//  - the loads graph: edges are packages loaded through the export data of
	//    imports
	//
	// By definition, loads < reaches < imports.
	type edgeSet map[PackageID]map[PackageID]bool
	var (
		imports    = make(edgeSet) // A imports B transitively
		importedBy = make(edgeSet) // A is imported by B transitively
		reaches    = make(edgeSet) // A reaches B through top-level declaration syntax
		reachedBy  = make(edgeSet) // A is reached by B through top-level declaration syntax
		loads      = make(edgeSet) // A loads B through export data of its direct dependencies
		loadedBy   = make(edgeSet) // A is loaded by B through export data of B's direct dependencies
	)
	recordEdge := func(from, to PackageID, fwd, rev edgeSet) {
		if fwd[from] == nil {
			fwd[from] = make(map[PackageID]bool)
		}
		fwd[from][to] = true
		if rev[to] == nil {
			rev[to] = make(map[PackageID]bool)
		}
		rev[to][from] = true
	}

	exportedPackages := make(map[PackageID]*types.Package)
	importPackage := func(id PackageID) *types.Package {
		exportFile := exports[id]
		if exportFile == "" {
			return nil // no exported symbols
		}
		mp := meta.Metadata(id)
		tpkg, ok := exportedPackages[id]
		if !ok {
			pkgPath := string(mp.PkgPath)
			tpkg, err = importFromExportData(pkgPath, exportFile)
			if err != nil {
				t.Fatalf("importFromExportData(%s, %s) failed: %v", pkgPath, exportFile, err)
			}
			exportedPackages[id] = tpkg
		}
		return tpkg
	}

	for _, id := range ids {
		pkg, err := g.Package(ctx, id)
		if err != nil {
			t.Fatal(err)
		}
		pkg.ReachesByDeps.Elems(func(id2 typerefs.IndexID) {
			recordEdge(id, g.pkgIndex.PackageID(id2), reaches, reachedBy)
		})

		importMap := importMap(id, meta)
		for _, id2 := range importMap {
			recordEdge(id, id2, imports, importedBy)
		}

		if *verify {
			for _, depID := range meta.Metadata(id).DepsByPkgPath {
				tpkg := importPackage(depID)
				if tpkg == nil {
					continue
				}
				for _, imp := range tpkg.Imports() {
					depID, ok := importMap[PackagePath(imp.Path())]
					if !ok {
						t.Errorf("import map (len: %d) for %s missing imported types.Package %s", len(importMap), id, imp.Path())
						continue
					}
					recordEdge(id, depID, loads, loadedBy)
				}
			}

			for depID := range loads[id] {
				if !pkg.ReachesByDeps.Contains(depID) {
					t.Errorf("package %s was imported by %s, but not detected as reachable", depID, id)
				}
			}
		}
	}

	if testing.Verbose() {
		fmt.Printf("%-52s%8s%8s%8s%8s%8s%8s\n", "package ID", "imp", "impBy", "reach", "reachBy", "load", "loadBy")
		for _, id := range ids {
			fmt.Printf("%-52s%8d%8d%8d%8d%8d%8d\n", id, len(imports[id]), len(importedBy[id]), len(reaches[id]), len(reachedBy[id]), len(loads[id]), len(loadedBy[id]))
		}
		fmt.Println(strings.Repeat("-", 100))
		fmt.Printf("%-52s%8s%8s%8s%8s%8s%8s\n", "package ID", "imp", "impBy", "reach", "reachBy", "load", "loadBy")

		avg := func(m edgeSet) float64 {
			var avg float64
			for _, id := range ids {
				s := m[id]
				avg += float64(len(s)) / float64(len(ids))
			}
			return avg
		}
		fmt.Printf("%52s%8.1f%8.1f%8.1f%8.1f%8.1f%8.1f\n", "averages:", avg(imports), avg(importedBy), avg(reaches), avg(reachedBy), avg(loads), avg(loadedBy))
	}
}

func importMap(id PackageID, meta MetadataSource) map[PackagePath]PackageID {
	imports := make(map[PackagePath]PackageID)
	var recordIDs func(PackageID)
	recordIDs = func(id PackageID) {
		mp := meta.Metadata(id)
		if _, ok := imports[mp.PkgPath]; ok {
			return
		}
		imports[mp.PkgPath] = id
		for _, id := range mp.DepsByPkgPath {
			recordIDs(id)
		}
	}
	for _, id := range meta.Metadata(id).DepsByPkgPath {
		recordIDs(id)
	}
	return imports
}

func importFromExportData(pkgPath, exportFile string) (*types.Package, error) {
	file, err := os.Open(exportFile)
	if err != nil {
		return nil, err
	}
	r, err := gcexportdata.NewReader(file)
	if err != nil {
		file.Close() // ignore error
		return nil, err
	}
	fset := token.NewFileSet()
	tpkg, err := gcexportdata.Read(r, fset, make(map[string]*types.Package), pkgPath)
	file.Close() // ignore error
	if err != nil {
		return nil, err
	}
	// The export file reported by go/packages is produced by the compiler, which
	// has additional package dependencies due to inlining.
	//
	// Export and re-import so that we only observe dependencies from the
	// exported API.
	var out bytes.Buffer
	err = gcexportdata.Write(&out, fset, tpkg)
	if err != nil {
		return nil, err
	}
	return gcexportdata.Read(&out, token.NewFileSet(), make(map[string]*types.Package), pkgPath)
}

func BenchmarkBuildPackageGraph(b *testing.B) {
	t0 := time.Now()
	exports, meta, err := loadPackages(*query, *verify)
	if err != nil {
		b.Fatalf("loading failed: %v", err)
	}
	b.Logf("loaded %d packages in %v", len(exports), time.Since(t0))
	ctx := context.Background()
	var ids []PackageID
	for id := range exports {
		ids = append(ids, id)
	}

	for b.Loop() {
		_, err := BuildPackageGraph(ctx, meta, ids, newParser().parse)
		if err != nil {
			b.Fatal(err)
		}
	}
}

type memoizedParser struct {
	mu    sync.Mutex
	files map[protocol.DocumentURI]*futureParse
}

type futureParse struct {
	done chan struct{}
	pgf  *parsego.File
	err  error
}

func newParser() *memoizedParser {
	return &memoizedParser{
		files: make(map[protocol.DocumentURI]*futureParse),
	}
}

func (p *memoizedParser) parse(ctx context.Context, uri protocol.DocumentURI) (*parsego.File, error) {
	doParse := func(ctx context.Context, uri protocol.DocumentURI) (*parsego.File, error) {
		// TODO(adonovan): hoist this operation outside the benchmark critsec.
		content, err := os.ReadFile(uri.Path())
		if err != nil {
			return nil, err
		}
		content = astutil.PurgeFuncBodies(content)
		pgf, _ := parsego.Parse(ctx, token.NewFileSet(), uri, content, parsego.Full, false)
		return pgf, nil
	}

	p.mu.Lock()
	fut, ok := p.files[uri]
	if ok {
		p.mu.Unlock()
		select {
		case <-fut.done:
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	} else {
		fut = &futureParse{done: make(chan struct{})}
		p.files[uri] = fut
		p.mu.Unlock()
		fut.pgf, fut.err = doParse(ctx, uri)
		close(fut.done)
	}
	return fut.pgf, fut.err
}

type mapMetadataSource struct {
	m map[PackageID]*Metadata
}

func (s mapMetadataSource) Metadata(id PackageID) *Metadata {
	return s.m[id]
}

// This function is a compressed version of snapshot.load from the
// internal/cache package, for use in testing.
//
// TODO(rfindley): it may be valuable to extract this logic from the snapshot,
// since it is otherwise standalone.
func loadPackages(query string, needExport bool) (map[PackageID]string, MetadataSource, error) {
	cfg := &packages.Config{
		Dir: *dir,
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedCompiledGoFiles |
			packages.NeedImports |
			packages.NeedDeps |
			packages.NeedTypesSizes |
			packages.NeedModule |
			packages.NeedEmbedFiles |
			packages.LoadMode(packagesinternal.DepsErrors) |
			packages.NeedForTest,
		Tests: true,
	}
	if needExport {
		cfg.Mode |= packages.NeedExportFile // ExportFile is not requested by gopls: this is used to verify reachability
	}
	pkgs, err := packages.Load(cfg, query)
	if err != nil {
		return nil, nil, err
	}

	meta := make(map[PackageID]*Metadata)
	var buildMetadata func(pkg *packages.Package)
	buildMetadata = func(pkg *packages.Package) {
		id := PackageID(pkg.ID)
		if meta[id] != nil {
			return
		}
		mp := &Metadata{
			ID:         id,
			PkgPath:    PackagePath(pkg.PkgPath),
			Name:       packageName(pkg.Name),
			ForTest:    PackagePath(pkg.ForTest),
			TypesSizes: pkg.TypesSizes,
			LoadDir:    cfg.Dir,
			Module:     pkg.Module,
			Errors:     pkg.Errors,
			DepsErrors: packagesinternal.GetDepsErrors(pkg),
		}
		meta[id] = mp

		for _, filename := range pkg.CompiledGoFiles {
			mp.CompiledGoFiles = append(mp.CompiledGoFiles, protocol.URIFromPath(filename))
		}
		for _, filename := range pkg.GoFiles {
			mp.GoFiles = append(mp.GoFiles, protocol.URIFromPath(filename))
		}

		mp.DepsByImpPath = make(map[ImportPath]PackageID)
		mp.DepsByPkgPath = make(map[PackagePath]PackageID)
		for importPath, imported := range pkg.Imports {
			importPath := ImportPath(importPath)

			// see note in gopls/internal/cache/load.go for an explanation of this check.
			if importPath != "unsafe" && len(imported.CompiledGoFiles) == 0 {
				mp.DepsByImpPath[importPath] = "" // missing
				continue
			}

			mp.DepsByImpPath[importPath] = PackageID(imported.ID)
			mp.DepsByPkgPath[PackagePath(imported.PkgPath)] = PackageID(imported.ID)
			buildMetadata(imported)
		}
	}

	exportFiles := make(map[PackageID]string)
	for _, pkg := range pkgs {
		exportFiles[PackageID(pkg.ID)] = pkg.ExportFile
		buildMetadata(pkg)
	}
	return exportFiles, &mapMetadataSource{meta}, nil
}


================================================
FILE: gopls/internal/cache/typerefs/refs.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typerefs

import (
	"fmt"
	"go/ast"
	"go/token"
	"sort"
	"strings"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/frob"
	"golang.org/x/tools/internal/astutil"
)

// Encode analyzes the Go syntax trees of a package, constructs a
// reference graph, and uses it to compute, for each exported
// declaration, the set of exported symbols of directly imported
// packages that it references, perhaps indirectly.
//
// It returns a serializable index of this information.
// Use Decode to expand the result.
func Encode(files []*parsego.File, imports map[metadata.ImportPath]*metadata.Package) []byte {
	return index(files, imports)
}

// Decode decodes a serializable index of symbol
// reachability produced by Encode.
//
// Because many declarations reference the exact same set of symbols,
// the results are grouped into equivalence classes.
// Classes are sorted by Decls[0], ascending.
// The class with empty reachability is omitted.
//
// See the package documentation for more details as to what a
// reference does (and does not) represent.
func Decode(pkgIndex *PackageIndex, data []byte) []Class {
	return decode(pkgIndex, data)
}

// A Class is a reachability equivalence class.
//
// It attests that each exported package-level declaration in Decls
// references (perhaps indirectly) one of the external (imported)
// symbols in Refs.
//
// Because many Decls reach the same Refs,
// it is more efficient to group them into classes.
type Class struct {
	Decls []string // sorted set of names of exported decls with same reachability
	Refs  []Symbol // set of external symbols, in ascending (PackageID, Name) order
}

// A Symbol represents an external (imported) symbol
// referenced by the analyzed package.
type Symbol struct {
	Package IndexID // w.r.t. PackageIndex passed to decoder
	Name    string
}

// An IndexID is a small integer that uniquely identifies a package within a
// given PackageIndex.
type IndexID int

// -- internals --

// A symbolSet is a set of symbols used internally during index construction.
//
// TODO(adonovan): opt: evaluate unifying Symbol and symbol.
// (Encode would have to create a private PackageIndex.)
type symbolSet map[symbol]bool

// A symbol is the internal representation of an external
// (imported) symbol referenced by the analyzed package.
type symbol struct {
	pkg  metadata.PackageID
	name string
}

// declNode holds information about a package-level declaration
// (or more than one with the same name, in ill-typed code).
//
// It is a node in the symbol reference graph, whose outgoing edges
// are of two kinds: intRefs and extRefs.
type declNode struct {
	name string
	rep  *declNode // canonical representative of this SCC (initially self)

	// outgoing graph edges
	intRefs      map[*declNode]bool // to symbols in this package
	extRefs      symbolSet          // to imported symbols
	extRefsClass int                // extRefs equivalence class number (-1 until set at end)

	// Tarjan's SCC algorithm
	index, lowlink int32 // Tarjan numbering
	scc            int32 // -ve => on stack; 0 => unvisited; +ve => node is root of a found SCC
}

// state holds the working state of the Refs algorithm for a single package.
//
// The number of distinct symbols referenced by a single package
// (measured across all of kubernetes), was found to be:
//   - max = 1750.
//   - Several packages reference > 100 symbols.
//   - p95 = 32, p90 = 22, p50 = 8.
type state struct {
	// numbering of unique symbol sets
	class      []symbolSet    // unique symbol sets
	classIndex map[string]int // index of above (using SymbolSet.hash as key)

	// Tarjan's SCC algorithm
	index int32
	stack []*declNode
}

// getClassIndex returns the small integer (an index into
// state.class) that identifies the given set.
func (st *state) getClassIndex(set symbolSet) int {
	key := classKey(set)
	i, ok := st.classIndex[key]
	if !ok {
		i = len(st.class)
		st.classIndex[key] = i
		st.class = append(st.class, set)
	}
	return i
}

// appendSorted appends the symbols to syms, sorts by ascending
// (PackageID, name), and returns the result.
// The argument must be an empty slice, ideally with capacity len(set).
func (set symbolSet) appendSorted(syms []symbol) []symbol {
	for sym := range set {
		syms = append(syms, sym)
	}
	sort.Slice(syms, func(i, j int) bool {
		x, y := syms[i], syms[j]
		if x.pkg != y.pkg {
			return x.pkg < y.pkg
		}
		return x.name < y.name
	})
	return syms
}

// classKey returns a key such that equal keys imply equal sets.
// (e.g. a sorted string representation, or a cryptographic hash of same).
func classKey(set symbolSet) string {
	// Sort symbols into a stable order.
	// TODO(adonovan): opt: a cheap crypto hash (e.g. BLAKE2b) might
	// make a cheaper map key than a large string.
	// Try using a hasher instead of a builder.
	var s strings.Builder
	for _, sym := range set.appendSorted(make([]symbol, 0, len(set))) {
		fmt.Fprintf(&s, "%s:%s;", sym.pkg, sym.name)
	}
	return s.String()
}

// index builds the reference graph and encodes the index.
func index(pgfs []*parsego.File, imports map[metadata.ImportPath]*metadata.Package) []byte {
	// First pass: gather package-level names and create a declNode for each.
	//
	// In ill-typed code, there may be multiple declarations of the
	// same name; a single declInfo node will represent them all.
	decls := make(map[string]*declNode)
	addDecl := func(id *ast.Ident) {
		if name := id.Name; name != "_" && decls[name] == nil {
			node := &declNode{name: name, extRefsClass: -1}
			node.rep = node
			decls[name] = node
		}
	}
	for _, pgf := range pgfs {
		for _, d := range pgf.File.Decls {
			switch d := d.(type) {
			case *ast.GenDecl:
				switch d.Tok {
				case token.TYPE:
					for _, spec := range d.Specs {
						addDecl(spec.(*ast.TypeSpec).Name)
					}

				case token.VAR, token.CONST:
					for _, spec := range d.Specs {
						for _, ident := range spec.(*ast.ValueSpec).Names {
							addDecl(ident)
						}
					}
				}

			case *ast.FuncDecl:
				// non-method functions
				if d.Recv.NumFields() == 0 {
					addDecl(d.Name)
				}
			}
		}
	}

	// Second pass: process files to collect referring identifiers.
	st := &state{classIndex: make(map[string]int)}
	for _, pgf := range pgfs {
		visitFile(pgf.File, imports, decls)
	}

	// Find the strong components of the declNode graph
	// using Tarjan's algorithm, and coalesce each component.
	st.index = 1
	for _, decl := range decls {
		if decl.index == 0 { // unvisited
			st.visit(decl)
		}
	}

	// TODO(adonovan): opt: consider compressing the serialized
	// representation by recording not the classes but the DAG of
	// non-trivial union operations (the "pointer equivalence"
	// optimization of Hardekopf & Lin). Unlike that algorithm,
	// which piggybacks on SCC coalescing, in our case it would
	// be better to make a forward traversal from the exported
	// decls, since it avoids visiting unreachable nodes, and
	// results in a dense (not sparse) numbering of the sets.

	// Tabulate the unique reachability sets of
	// each exported package member.
	classNames := make(map[int][]string) // set of decls (names) for a given reachability set
	for name, decl := range decls {
		if !ast.IsExported(name) {
			continue
		}

		decl = decl.find()

		// Skip decls with empty reachability.
		if len(decl.extRefs) == 0 {
			continue
		}

		// Canonicalize the set (and memoize).
		class := decl.extRefsClass
		if class < 0 {
			class = st.getClassIndex(decl.extRefs)
			decl.extRefsClass = class
		}
		classNames[class] = append(classNames[class], name)
	}

	return encode(classNames, st.class)
}

// visitFile inspects the file syntax for referring identifiers, and
// populates the internal and external references of decls.
func visitFile(file *ast.File, imports map[metadata.ImportPath]*metadata.Package, decls map[string]*declNode) {
	// Import information for this file. Multiple packages
	// may be referenced by a given name in the presence
	// of type errors (or multiple dot imports, which are
	// keyed by ".").
	fileImports := make(map[string][]metadata.PackageID)

	// importEdge records a reference from decl to an imported symbol
	// (pkgname.name). The package name may be ".".
	importEdge := func(decl *declNode, pkgname, name string) {
		if token.IsExported(name) {
			for _, depID := range fileImports[pkgname] {
				if decl.extRefs == nil {
					decl.extRefs = make(symbolSet)
				}
				decl.extRefs[symbol{depID, name}] = true
			}
		}
	}

	// visit finds refs within node and builds edges from fromId's decl.
	// References to the type parameters are ignored.
	visit := func(fromId *ast.Ident, node ast.Node, tparams map[string]bool) {
		if fromId.Name == "_" {
			return
		}
		from := decls[fromId.Name]
		// When visiting a method, there may not be a valid type declaration for
		// the receiver. In this case there is no way to refer to the method, so
		// we need not record edges.
		if from == nil {
			return
		}

		// Visit each reference to name or name.sel.
		visitDeclOrSpec(node, func(name, sel string) {
			// Ignore references to type parameters.
			if tparams[name] {
				return
			}

			// If name is declared in the package scope,
			// record an edge whether or not sel is empty.
			// A field or method selector may affect the
			// type of the current decl via initializers:
			//
			//  package p
			//  var x = y.F
			//  var y = struct{ F int }{}
			if to, ok := decls[name]; ok {
				if from.intRefs == nil {
					from.intRefs = make(map[*declNode]bool)
				}
				from.intRefs[to] = true

			} else {
				// Only record an edge to dot-imported packages
				// if there was no edge to a local name.
				// This assumes that there are no duplicate declarations.
				// We conservatively, assume that this name comes from
				// every dot-imported package.
				importEdge(from, ".", name)
			}

			// Record an edge to an import if it matches the name, even if that
			// name collides with a package level name. Unlike the case of dotted
			// imports, we know the package is invalid here, and choose to fail
			// conservatively.
			if sel != "" {
				importEdge(from, name, sel)
			}
		})
	}

	// Visit the declarations and gather reference edges.
	// Import declarations appear before all others.
	for _, d := range file.Decls {
		switch d := d.(type) {
		case *ast.GenDecl:
			switch d.Tok {
			case token.IMPORT:
				// Record local import names for this file.
				for _, spec := range d.Specs {
					spec := spec.(*ast.ImportSpec)
					path := metadata.UnquoteImportPath(spec)
					if path == "" {
						continue
					}
					dep := imports[path]
					if dep == nil {
						// Note here that we don't try to "guess"
						// the name of an import based on e.g.
						// its importPath. Doing so would only
						// result in edges that don't go anywhere.
						continue
					}
					name := string(dep.Name)
					if spec.Name != nil {
						if spec.Name.Name == "_" {
							continue
						}
						name = spec.Name.Name // possibly "."
					}
					fileImports[name] = append(fileImports[name], dep.ID)
				}

			case token.TYPE:
				for _, spec := range d.Specs {
					spec := spec.(*ast.TypeSpec)
					tparams := tparamsMap(spec.TypeParams)
					visit(spec.Name, spec, tparams)
				}

			case token.VAR, token.CONST:
				for _, spec := range d.Specs {
					spec := spec.(*ast.ValueSpec)
					for _, name := range spec.Names {
						visit(name, spec, nil)
					}
				}
			}

		case *ast.FuncDecl:
			// This check for NumFields() > 0 is consistent with go/types,
			// which reports an error but treats the declaration like a
			// normal function when Recv is non-nil but empty
			// (as in func () f()).
			if d.Recv.NumFields() > 0 {
				// Method. Associate it with the receiver.
				_, id, typeParams := astutil.UnpackRecv(d.Recv.List[0].Type)
				if id != nil {
					var tparams map[string]bool
					if len(typeParams) > 0 {
						tparams = make(map[string]bool)
						for _, tparam := range typeParams {
							if tparam.Name != "_" {
								tparams[tparam.Name] = true
							}
						}
					}
					visit(id, d, tparams)
				}
			} else {
				// Non-method.
				tparams := tparamsMap(d.Type.TypeParams)
				visit(d.Name, d, tparams)
			}
		}
	}
}

// tparamsMap returns a set recording each name declared by the provided field
// list. It so happens that we only care about names declared by type parameter
// lists.
func tparamsMap(tparams *ast.FieldList) map[string]bool {
	if tparams == nil || len(tparams.List) == 0 {
		return nil
	}
	m := make(map[string]bool)
	for _, f := range tparams.List {
		for _, name := range f.Names {
			if name.Name != "_" {
				m[name.Name] = true
			}
		}
	}
	return m
}

// A refVisitor visits referring identifiers and dotted identifiers.
//
// For a referring identifier I, name="I" and sel="". For a dotted identifier
// q.I, name="q" and sel="I".
type refVisitor = func(name, sel string)

// visitDeclOrSpec visits referring idents or dotted idents that may affect
// the type of the declaration at the given node, which must be an ast.Decl or
// ast.Spec.
func visitDeclOrSpec(node ast.Node, f refVisitor) {
	// Declarations
	switch n := node.(type) {
	// ImportSpecs should not appear here, and will panic in the default case.

	case *ast.ValueSpec:
		// Skip Doc, Names, Comments, which do not affect the decl type.
		// Initializers only affect the type of a value spec if the type is unset.
		if n.Type != nil {
			visitExpr(n.Type, f)
		} else { // only need to walk expr list if type is nil
			visitExprList(n.Values, f)
		}

	case *ast.TypeSpec:
		// Skip Doc, Name, and Comment, which do not affect the decl type.
		if tparams := n.TypeParams; tparams != nil {
			visitFieldList(tparams, f)
		}
		visitExpr(n.Type, f)

	case *ast.BadDecl:
		// nothing to do

	// We should not reach here with a GenDecl, so panic below in the default case.

	case *ast.FuncDecl:
		// Skip Doc, Name, and Body, which do not affect the type.
		// Recv is handled by Refs: methods are associated with their type.
		visitExpr(n.Type, f)

	default:
		panic(fmt.Sprintf("unexpected node type %T", node))
	}
}

// visitExpr visits referring idents and dotted idents that may affect the
// type of expr.
//
// visitExpr can't reliably distinguish a dotted ident pkg.X from a
// selection expr.f or T.method.
func visitExpr(expr ast.Expr, f refVisitor) {
	switch n := expr.(type) {
	// These four cases account for about two thirds of all nodes,
	// so we place them first to shorten the common control paths.
	// (See go.dev/cl/480915.)
	case *ast.Ident:
		f(n.Name, "")

	case *ast.BasicLit:
		// nothing to do

	case *ast.SelectorExpr:
		if ident, ok := n.X.(*ast.Ident); ok {
			f(ident.Name, n.Sel.Name)
		} else {
			visitExpr(n.X, f)
			// Skip n.Sel as we don't care about which field or method is selected,
			// as we'll have recorded an edge to all declarations relevant to the
			// receiver type via visiting n.X above.
		}

	case *ast.CallExpr:
		visitExpr(n.Fun, f)
		visitExprList(n.Args, f) // args affect types for unsafe.Sizeof or builtins or generics

	// Expressions
	case *ast.Ellipsis:
		if n.Elt != nil {
			visitExpr(n.Elt, f)
		}

	case *ast.FuncLit:
		visitExpr(n.Type, f)
		// Skip Body, which does not affect the type.

	case *ast.CompositeLit:
		if n.Type != nil {
			visitExpr(n.Type, f)
		}
		// Skip Elts, which do not affect the type.

	case *ast.ParenExpr:
		visitExpr(n.X, f)

	case *ast.IndexExpr:
		visitExpr(n.X, f)
		visitExpr(n.Index, f) // may affect type for instantiations

	case *ast.IndexListExpr:
		visitExpr(n.X, f)
		for _, index := range n.Indices {
			visitExpr(index, f) // may affect the type for instantiations
		}

	case *ast.SliceExpr:
		visitExpr(n.X, f)
		// skip Low, High, and Max, which do not affect type.

	case *ast.TypeAssertExpr:
		// Skip X, as it doesn't actually affect the resulting type of the type
		// assertion.
		if n.Type != nil {
			visitExpr(n.Type, f)
		}

	case *ast.StarExpr:
		visitExpr(n.X, f)

	case *ast.UnaryExpr:
		visitExpr(n.X, f)

	case *ast.BinaryExpr:
		visitExpr(n.X, f)
		visitExpr(n.Y, f)

	case *ast.KeyValueExpr:
		panic("unreachable") // unreachable, as we don't descend into elts of composite lits.

	case *ast.ArrayType:
		if n.Len != nil {
			visitExpr(n.Len, f)
		}
		visitExpr(n.Elt, f)

	case *ast.StructType:
		visitFieldList(n.Fields, f)

	case *ast.FuncType:
		if tparams := n.TypeParams; tparams != nil {
			visitFieldList(tparams, f)
		}
		if n.Params != nil {
			visitFieldList(n.Params, f)
		}
		if n.Results != nil {
			visitFieldList(n.Results, f)
		}

	case *ast.InterfaceType:
		visitFieldList(n.Methods, f)

	case *ast.MapType:
		visitExpr(n.Key, f)
		visitExpr(n.Value, f)

	case *ast.ChanType:
		visitExpr(n.Value, f)

	case *ast.BadExpr:
		// nothing to do

	default:
		panic(fmt.Sprintf("ast.Walk: unexpected node type %T", n))
	}
}

func visitExprList(list []ast.Expr, f refVisitor) {
	for _, x := range list {
		visitExpr(x, f)
	}
}

func visitFieldList(n *ast.FieldList, f refVisitor) {
	for _, field := range n.List {
		visitExpr(field.Type, f)
	}
}

// -- strong component graph construction (plundered from go/pointer) --

// visit implements the depth-first search of Tarjan's SCC algorithm
// (see https://doi.org/10.1137/0201010).
// Precondition: x is canonical.
func (st *state) visit(x *declNode) {
	checkCanonical(x)
	x.index = st.index
	x.lowlink = st.index
	st.index++

	st.stack = append(st.stack, x) // push
	assert(x.scc == 0, "node revisited")
	x.scc = -1

	for y := range x.intRefs {
		// Loop invariant: x is canonical.

		y := y.find()

		if x == y {
			continue // nodes already coalesced
		}

		switch {
		case y.scc > 0:
			// y is already a collapsed SCC

		case y.scc < 0:
			// y is on the stack, and thus in the current SCC.
			if y.index < x.lowlink {
				x.lowlink = y.index
			}

		default:
			// y is unvisited; visit it now.
			st.visit(y)
			// Note: x and y are now non-canonical.

			x = x.find()

			if y.lowlink < x.lowlink {
				x.lowlink = y.lowlink
			}
		}
	}
	checkCanonical(x)

	// Is x the root of an SCC?
	if x.lowlink == x.index {
		// Coalesce all nodes in the SCC.
		for {
			// Pop y from stack.
			i := len(st.stack) - 1
			y := st.stack[i]
			st.stack = st.stack[:i]

			checkCanonical(x)
			checkCanonical(y)

			if x == y {
				break // SCC is complete.
			}
			coalesce(x, y)
		}

		// Accumulate union of extRefs over
		// internal edges (to other SCCs).
		for y := range x.intRefs {
			y := y.find()
			if y == x {
				continue // already coalesced
			}
			assert(y.scc == 1, "edge to non-scc node")
			for z := range y.extRefs {
				if x.extRefs == nil {
					x.extRefs = make(symbolSet)
				}
				x.extRefs[z] = true // extRefs: x U= y
			}
		}

		x.scc = 1
	}
}

// coalesce combines two nodes in the strong component graph.
// Precondition: x and y are canonical.
func coalesce(x, y *declNode) {
	// x becomes y's canonical representative.
	y.rep = x

	// x accumulates y's internal references.
	for z := range y.intRefs {
		x.intRefs[z] = true
	}
	y.intRefs = nil

	// x accumulates y's external references.
	for z := range y.extRefs {
		if x.extRefs == nil {
			x.extRefs = make(symbolSet)
		}
		x.extRefs[z] = true
	}
	y.extRefs = nil
}

// find returns the canonical node decl.
// (The nodes form a disjoint set forest.)
func (decl *declNode) find() *declNode {
	rep := decl.rep
	if rep != decl {
		rep = rep.find()
		decl.rep = rep // simple path compression (no union-by-rank)
	}
	return rep
}

const debugSCC = false // enable assertions in strong-component algorithm

func checkCanonical(x *declNode) {
	if debugSCC {
		assert(x == x.find(), "not canonical")
	}
}

func assert(cond bool, msg string) {
	if debugSCC && !cond {
		panic(msg)
	}
}

// -- serialization --

// (The name says gob but in fact we use frob.)
var classesCodec = frob.CodecFor[gobClasses]()

type gobClasses struct {
	Strings []string // table of strings (PackageIDs and names)
	Classes []gobClass
}

type gobClass struct {
	Decls []int32 // indices into gobClasses.Strings
	Refs  []int32 // list of (package, name) pairs, each an index into gobClasses.Strings
}

// encode encodes the equivalence classes,
// (classNames[i], classes[i]), for i in range classes.
//
// With the current encoding, across kubernetes,
// the encoded size distribution has
// p50 = 511B, p95 = 4.4KB, max = 108K.
func encode(classNames map[int][]string, classes []symbolSet) []byte {
	payload := gobClasses{
		Classes: make([]gobClass, 0, len(classNames)),
	}

	// index of unique strings
	strings := make(map[string]int32)
	stringIndex := func(s string) int32 {
		i, ok := strings[s]
		if !ok {
			i = int32(len(payload.Strings))
			strings[s] = i
			payload.Strings = append(payload.Strings, s)
		}
		return i
	}

	var refs []symbol // recycled temporary
	for class, names := range classNames {
		set := classes[class]

		// names, sorted
		sort.Strings(names)
		gobDecls := make([]int32, len(names))
		for i, name := range names {
			gobDecls[i] = stringIndex(name)
		}

		// refs, sorted by ascending (PackageID, name)
		gobRefs := make([]int32, 0, 2*len(set))
		for _, sym := range set.appendSorted(refs[:0]) {
			gobRefs = append(gobRefs,
				stringIndex(string(sym.pkg)),
				stringIndex(sym.name))
		}
		payload.Classes = append(payload.Classes, gobClass{
			Decls: gobDecls,
			Refs:  gobRefs,
		})
	}

	return classesCodec.Encode(payload)
}

func decode(pkgIndex *PackageIndex, data []byte) []Class {
	var payload gobClasses
	classesCodec.Decode(data, &payload)

	classes := make([]Class, len(payload.Classes))
	for i, gobClass := range payload.Classes {
		decls := make([]string, len(gobClass.Decls))
		for i, decl := range gobClass.Decls {
			decls[i] = payload.Strings[decl]
		}
		refs := make([]Symbol, len(gobClass.Refs)/2)
		for i := range refs {
			pkgID := pkgIndex.IndexID(metadata.PackageID(payload.Strings[gobClass.Refs[2*i]]))
			name := payload.Strings[gobClass.Refs[2*i+1]]
			refs[i] = Symbol{Package: pkgID, Name: name}
		}
		classes[i] = Class{
			Decls: decls,
			Refs:  refs,
		}
	}

	// Sort by ascending Decls[0].
	// TODO(adonovan): move sort to encoder. Determinism is good.
	sort.Slice(classes, func(i, j int) bool {
		return classes[i].Decls[0] < classes[j].Decls[0]
	})

	return classes
}


================================================
FILE: gopls/internal/cache/typerefs/refs_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typerefs_test

import (
	"context"
	"fmt"
	"go/token"
	"sort"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/protocol"
)

// TestRefs checks that the analysis reports, for each exported member
// of the test package ("p"), its correct dependencies on exported
// members of its direct imports (e.g. "ext").
func TestRefs(t *testing.T) {
	ctx := context.Background()

	tests := []struct {
		label     string
		srcs      []string            // source for the local package; package name must be p
		imports   map[string]string   // for simplicity: importPath -> pkgID/pkgName (we set pkgName == pkgID); 'ext' is always available.
		want      map[string][]string // decl name -> id.<decl name>
		allowErrs bool                // whether we expect parsing errors
	}{
		{
			label: "empty package",
			want:  map[string][]string{},
		},
		{
			label: "fields",
			srcs: []string{`
package p

import "ext"

type A struct{ b B }
type B func(c C) (d D)
type C ext.C
type D ext.D

// Should not be referenced by field names.
type b ext.B_
type c int.C_
type d ext.D_
`},
			want: map[string][]string{
				"A": {"ext.C", "ext.D"},
				"B": {"ext.C", "ext.D"},
				"C": {"ext.C"},
				"D": {"ext.D"},
			},
		},
		{
			label: "embedding",
			srcs: []string{`
package p

import "ext"

type A struct{
	B
	_ struct {
		C
	}
	D
}
type B ext.B
type C ext.C
type D interface{
	B
}
`},
			want: map[string][]string{
				"A": {"ext.B", "ext.C"},
				"B": {"ext.B"},
				"C": {"ext.C"},
				"D": {"ext.B"},
			},
		},
		{
			label: "constraint embedding",
			srcs: []string{`
package p

import "ext"

type A interface{
	int | B | ~C
	struct{D}
}

type B ext.B
type C ext.C
type D ext.D
`},
			want: map[string][]string{
				"A": {"ext.B", "ext.C", "ext.D"},
				"B": {"ext.B"},
				"C": {"ext.C"},
				"D": {"ext.D"},
			},
		},
		{
			label: "funcs",
			srcs: []string{`
package p

import "ext"

type A ext.A
type B ext.B
const C B = 2
func F(A) B {
	return C
}
var V = F(W)
var W A
`},
			want: map[string][]string{
				"A": {"ext.A"},
				"B": {"ext.B"},
				"C": {"ext.B"},
				"F": {"ext.A", "ext.B"},
				"V": {
					"ext.A", // via F
					"ext.B", // via W: can't be eliminated: F could be builtin or generic
				},
				"W": {"ext.A"},
			},
		},
		{
			label: "methods",
			srcs: []string{`package p

import "ext"

type A ext.A
type B ext.B
`, `package p

func (A) M(B)
func (*B) M(A)
`},
			want: map[string][]string{
				"A": {"ext.A", "ext.B"},
				"B": {"ext.A", "ext.B"},
			},
		},
		{
			label: "initializers",
			srcs: []string{`
package p

import "ext"

var A b = C // type does not depend on C
type b ext.B
var C = d // type does depend on D
var d b

var e = d + a

var F = func() B { return E }

var G = struct{
	A b
	_ [unsafe.Sizeof(ext.V)]int // array size + Sizeof creates edge to a var
	_ [unsafe.Sizeof(G)]int // creates a self edge; doesn't affect output though
}{}

var H = (D + A + C*C)

var I = (A+C).F
`},
			want: map[string][]string{
				"A": {"ext.B"},
				"C": {"ext.B"},          // via d
				"G": {"ext.B", "ext.V"}, // via b,C
				"H": {"ext.B"},          // via d,A,C
				"I": {"ext.B"},
			},
		},
		{
			label: "builtins",
			srcs: []string{`package p

import "ext"

var A = new(b)
type b struct{ ext.B }

type C chan d
type d ext.D

type S []ext.S
type t ext.T
var U = append(([]*S)(nil), new(t))

type X map[k]v
type k ext.K
type v ext.V

var Z = make(map[k]A)

// close, delete, and panic cannot occur outside of statements
`},
			want: map[string][]string{
				"A": {"ext.B"},
				"C": {"ext.D"},
				"S": {"ext.S"},
				"U": {"ext.S", "ext.T"}, // ext.T edge could be eliminated
				"X": {"ext.K", "ext.V"},
				"Z": {"ext.B", "ext.K"},
			},
		},
		{
			label: "builtin shadowing",
			srcs: []string{`package p

import "ext"

var A = new(ext.B)
func new() c
type c ext.C
`},
			want: map[string][]string{
				"A": {"ext.B", "ext.C"},
			},
		},
		{
			label: "named forwarding",
			srcs: []string{`package p

import "ext"

type A B
type B c
type c ext.C
`},
			want: map[string][]string{
				"A": {"ext.C"},
				"B": {"ext.C"},
			},
		},
		{
			label: "aliases",
			srcs: []string{`package p

import "ext"

type A = B
type B = C
type C = ext.C
`},
			want: map[string][]string{
				"A": {"ext.C"},
				"B": {"ext.C"},
				"C": {"ext.C"},
			},
		},
		{
			label: "array length",
			srcs: []string{`package p

import "ext"
import "unsafe"

type A [unsafe.Sizeof(ext.B{ext.C})]int
type A2 [unsafe.Sizeof(ext.B{f:ext.C})]int // use a KeyValueExpr

type D [unsafe.Sizeof(struct{ f E })]int
type E ext.E

type F [3]G
type G [ext.C]int
`},
			want: map[string][]string{
				"A":  {"ext.B"}, // no ext.C: doesn't enter CompLit
				"A2": {"ext.B"}, // ditto
				"D":  {"ext.E"},
				"E":  {"ext.E"},
				"F":  {"ext.C"},
				"G":  {"ext.C"},
			},
		},
		{
			label: "imports",
			srcs: []string{`package p

import "ext"

import (
	"q"
	r2 "r"
	"s" // note: package name is t
	"z"
)

type A struct {
	q.Q
	r2.R
	s.S // invalid ref
	z.Z // references both external z.Z as well as package-level type z
}

type B struct {
	r.R // invalid ref
	t.T
}

var X int = q.V // X={}: no descent into RHS of 'var v T = rhs'
var Y = q.V.W

type z ext.Z
`},
			imports: map[string]string{"q": "q", "r": "r", "s": "t", "z": "z"},
			want: map[string][]string{
				"A": {"ext.Z", "q.Q", "r.R", "z.Z"},
				"B": {"t.T"},
				"Y": {"q.V"},
			},
		},
		{
			label: "import blank",
			srcs: []string{`package p

import _ "q"

type A q.Q
`},
			imports: map[string]string{"q": "q"},
			want:    map[string][]string{},
		},
		{
			label: "import dot",
			srcs: []string{`package p

import . "q"

type A q.Q // not actually an edge, since q is imported .
type B struct {
	C // assumed to be an edge to q
	D // resolved to package decl
}


type E error // unexported, therefore must be universe.error
type F Field
var G = Field.X
`, `package p

import "ext"
import "q"

type D ext.D
`},
			imports: map[string]string{"q": "q"},
			want: map[string][]string{
				"B": {"ext.D", "q.C"},
				"D": {"ext.D"},
				"F": {"q.Field"},
				"G": {"q.Field"},
			},
		},
		{
			label: "typeparams",
			srcs: []string{`package p

import "ext"

type A[T any] struct {
	t T
	b B
}

type B ext.B

func F1[T any](T, B)
func F2[T C]()(T, B)

type T ext.T

type C ext.C

func F3[T1 ~[]T2, T2 ~[]T3](t1 T1, t2 T2)
type T3 ext.T3
`, `package p

func (A[B]) M(C) {}
`},
			want: map[string][]string{
				"A":  {"ext.B", "ext.C"},
				"B":  {"ext.B"},
				"C":  {"ext.C"},
				"F1": {"ext.B"},
				"F2": {"ext.B", "ext.C"},
				"F3": {"ext.T3"},
				"T":  {"ext.T"},
				"T3": {"ext.T3"},
			},
		},
		{
			label: "instances",
			srcs: []string{`package p

import "ext"

type A[T any] ext.A
type B[T1, T2 any] ext.B

type C A[int]
type D B[int, A[E]]
type E ext.E
`},
			want: map[string][]string{
				"A": {"ext.A"},
				"B": {"ext.B"},
				"C": {"ext.A"},
				"D": {"ext.A", "ext.B", "ext.E"},
				"E": {"ext.E"},
			},
		},
		{
			label: "duplicate decls",
			srcs: []string{`package p

import "a"
import "ext"

type a a.A
type A a
type b ext.B
type C a.A
func (C) Foo(x) {} // invalid parameter, but that does not matter
type C b
func (C) Bar(y) {} // invalid parameter, but that does not matter

var x ext.X
var y ext.Y
`},
			imports: map[string]string{"a": "a", "b": "b"}, // "b" import should not matter, since it isn't in this file
			want: map[string][]string{
				"A": {"a.A"},
				"C": {"a.A", "ext.B", "ext.X", "ext.Y"},
			},
		},
		{
			label: "invalid decls",
			srcs: []string{`package p

import "ext"

type A B

func () Foo(B){}

var B struct{ ext.B
`},
			want: map[string][]string{
				"A":   {"ext.B"},
				"B":   {"ext.B"},
				"Foo": {"ext.B"},
			},
			allowErrs: true,
		},
		{
			label: "unmapped receiver",
			srcs: []string{`package p

type P struct{}

func (a) x(P)
`},
			want:      map[string][]string{},
			allowErrs: true,
		},
		{
			label: "SCC special case",
			srcs: []string{`package p

import "ext"

type X Y
type Y struct { Z; *X }
type Z map[ext.A]ext.B
`},
			want: map[string][]string{
				"X": {"ext.A", "ext.B"},
				"Y": {"ext.A", "ext.B"},
				"Z": {"ext.A", "ext.B"},
			},
			allowErrs: true,
		},
	}

	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			var pgfs []*parsego.File
			for i, src := range test.srcs {
				uri := protocol.DocumentURI(fmt.Sprintf("file:///%d.go", i))
				pgf, _ := parsego.Parse(ctx, token.NewFileSet(), uri, []byte(src), parsego.Full, false)
				if !test.allowErrs && pgf.ParseErr != nil {
					t.Fatalf("ParseGoSrc(...) returned parse errors: %v", pgf.ParseErr)
				}
				pgfs = append(pgfs, pgf)
			}

			imports := map[metadata.ImportPath]*metadata.Package{
				"ext": {ID: "ext", Name: "ext"}, // this one comes for free
			}
			for path, mp := range test.imports {
				imports[metadata.ImportPath(path)] = &metadata.Package{
					ID:   metadata.PackageID(mp),
					Name: metadata.PackageName(mp),
				}
			}

			data := typerefs.Encode(pgfs, imports)

			got := make(map[string][]string)
			index := typerefs.NewPackageIndex()
			for _, class := range typerefs.Decode(index, data) {
				// We redundantly expand out the name x refs cross product
				// here since that's what the existing tests expect.
				for _, name := range class.Decls {
					var syms []string
					for _, sym := range class.Refs {
						syms = append(syms, fmt.Sprintf("%s.%s", index.DeclaringPackage(sym), sym.Name))
					}
					sort.Strings(syms)
					got[name] = syms
				}
			}

			if diff := cmp.Diff(test.want, got); diff != "" {
				t.Errorf("Refs(...) returned unexpected refs (-want +got):\n%s", diff)
			}
		})
	}
}


================================================
FILE: gopls/internal/cache/view.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cache is the core of gopls: it is concerned with state
// management, dependency analysis, and invalidation; and it holds the
// machinery of type checking and modular static analysis. Its
// principal types are [Session], [Folder], [View], [Snapshot],
// [Cache], and [Package].
package cache

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"maps"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"slices"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/cache/typerefs"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/pathutil"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/modindex"
	"golang.org/x/tools/internal/xcontext"
)

// A Folder represents an LSP workspace folder, together with its per-folder
// options and environment variables that affect build configuration.
//
// Folders (Name and Dir) are specified by the 'initialize' and subsequent
// 'didChangeWorkspaceFolders' requests; their options come from
// didChangeConfiguration.
//
// Folders must not be mutated, as they may be shared across multiple views.
type Folder struct {
	Dir     protocol.DocumentURI
	Name    string // decorative name for UI; not necessarily unique
	Options *settings.Options
	Env     GoEnv
}

// GoEnv holds the environment variables and data from the Go command that is
// required for operating on a workspace folder.
type GoEnv struct {
	// Go environment variables. These correspond directly with the Go env var of
	// the same name.
	GOOS        string
	GOARCH      string
	GOCACHE     string
	GOMODCACHE  string
	GOPATH      string
	GOPRIVATE   string
	GOFLAGS     string
	GO111MODULE string
	GOTOOLCHAIN string
	GOROOT      string

	// Go version output.
	GoVersion       int    // The X in Go 1.X
	GoVersionOutput string // complete go version output

	// OS environment variables (notably not go env).

	// ExplicitGOWORK is the GOWORK value set explicitly in the environment. This
	// may differ from `go env GOWORK` when the GOWORK value is implicit from the
	// working directory.
	ExplicitGOWORK string

	// EffectiveGOPACKAGESDRIVER is the effective go/packages driver binary that
	// will be used. This may be set via GOPACKAGESDRIVER, or may be discovered
	// via os.LookPath("gopackagesdriver"). The latter functionality is
	// undocumented and may be removed in the future.
	//
	// If GOPACKAGESDRIVER is set to "off", EffectiveGOPACKAGESDRIVER is "".
	EffectiveGOPACKAGESDRIVER string
}

// View represents a single build for a workspace.
//
// A View is a logical build (the viewDefinition) along with a state of that
// build (the Snapshot).
type View struct {
	id string // a unique string to identify this View in (e.g.) serialized Commands

	*viewDefinition // build configuration

	gocmdRunner *gocommand.Runner // limits go command concurrency

	// baseCtx is the context handed to NewView. This is the parent of all
	// background contexts created for this view.
	baseCtx context.Context

	// importsState is for the old imports code
	importsState *importsState

	// modcacheState is the replacement for importsState, to be used for
	// goimports operations when the imports source is "gopls".
	//
	// It may be nil, if the imports source is not "gopls".
	modcacheState *modcacheState

	// pkgIndex is an index of package IDs, for efficient storage of typerefs.
	pkgIndex *typerefs.PackageIndex

	// parseCache holds an LRU cache of recently parsed files.
	parseCache *parseCache

	// fs is the file source used to populate this view.
	fs *overlayFS

	// ignoreFilter is used for fast checking of ignored files.
	ignoreFilter *ignoreFilter

	// cancelInitialWorkspaceLoad can be used to terminate the view's first
	// attempt at initialization.
	cancelInitialWorkspaceLoad context.CancelFunc

	snapshotMu sync.Mutex
	snapshot   *Snapshot // latest snapshot; nil after shutdown has been called

	// initialWorkspaceLoad is closed when the first workspace initialization has
	// completed. If we failed to load, we only retry if the go.mod file changes,
	// to avoid too many go/packages calls.
	initialWorkspaceLoad chan struct{}

	// initializationSema is used limit concurrent initialization of snapshots in
	// the view. We use a channel instead of a mutex to avoid blocking when a
	// context is canceled.
	//
	// This field (along with snapshot.initialized) guards against duplicate
	// initialization of snapshots. Do not change it without adjusting snapshot
	// accordingly.
	initializationSema chan struct{}

	// Document filters are constructed once, in View.filterFunc.
	filterFuncOnce sync.Once
	_filterFunc    func(protocol.DocumentURI) bool // only accessed by View.filterFunc
}

// definition implements the viewDefiner interface.
func (v *View) definition() *viewDefinition { return v.viewDefinition }

// A viewDefinition is a logical build, i.e. configuration (Folder) along with
// a build directory and possibly an environment overlay (e.g. GOWORK=off or
// GOOS, GOARCH=...) to affect the build.
//
// This type is immutable, and compared to see if the View needs to be
// reconstructed.
//
// Note: whenever modifying this type, also modify the equivalence relation
// implemented by viewDefinitionsEqual.
//
// TODO(golang/go#57979): viewDefinition should be sufficient for running
// go/packages. Enforce this in the API.
type viewDefinition struct {
	folder *Folder // pointer comparison is OK, as any new Folder creates a new def

	typ    ViewType
	root   protocol.DocumentURI // root directory; where to run the Go command
	gomod  protocol.DocumentURI // the nearest go.mod file, or ""
	gowork protocol.DocumentURI // the nearest go.work file, or ""

	// workspaceModFiles holds the set of mod files active in this snapshot.
	//
	// For a go.work workspace, this is the set of workspace modfiles. For a
	// go.mod workspace, this contains the go.mod file defining the workspace
	// root, as well as any locally replaced modules (if
	// "includeReplaceInWorkspace" is set).
	//
	// TODO(rfindley): should we just run `go list -m` to compute this set?
	workspaceModFiles    map[protocol.DocumentURI]struct{}
	workspaceModFilesErr error // error encountered computing workspaceModFiles

	// envOverlay holds additional environment to apply to this viewDefinition.
	envOverlay map[string]string
}

// definition implements the viewDefiner interface.
func (d *viewDefinition) definition() *viewDefinition { return d }

// Type returns the ViewType type, which determines how go/packages are loaded
// for this View.
func (d *viewDefinition) Type() ViewType { return d.typ }

// Root returns the view root, which determines where packages are loaded from.
func (d *viewDefinition) Root() protocol.DocumentURI { return d.root }

// GoMod returns the nearest go.mod file for this view's root, or "".
func (d *viewDefinition) GoMod() protocol.DocumentURI { return d.gomod }

// GoWork returns the nearest go.work file for this view's root, or "".
func (d *viewDefinition) GoWork() protocol.DocumentURI { return d.gowork }

// EnvOverlay returns a new sorted slice of environment variables (in the form
// "k=v") for this view definition's env overlay.
func (d *viewDefinition) EnvOverlay() []string {
	var env []string
	for k, v := range d.envOverlay {
		env = append(env, fmt.Sprintf("%s=%s", k, v))
	}
	sort.Strings(env)
	return env
}

// GOOS returns the effective GOOS value for this view definition, accounting
// for its env overlay.
func (d *viewDefinition) GOOS() string {
	if goos, ok := d.envOverlay["GOOS"]; ok {
		return goos
	}
	return d.folder.Env.GOOS
}

// GOARCH returns the effective GOARCH value for this view definition, accounting
// for its env overlay.
func (d *viewDefinition) GOARCH() string {
	if goarch, ok := d.envOverlay["GOARCH"]; ok {
		return goarch
	}
	return d.folder.Env.GOARCH
}

// adjustedGO111MODULE is the value of GO111MODULE to use for loading packages.
// It is adjusted to default to "auto" rather than "on", since if we are in
// GOPATH and have no module, we may as well allow a GOPATH view to work.
func (d viewDefinition) adjustedGO111MODULE() string {
	if d.folder.Env.GO111MODULE != "" {
		return d.folder.Env.GO111MODULE
	}
	return "auto"
}

// ModFiles returns a new, sorted slice of go.mod files for main modules
// enclosed in the snapshot's view and known to the snapshot.
func (d viewDefinition) ModFiles() []protocol.DocumentURI {
	return slices.Sorted(maps.Keys(d.workspaceModFiles))
}

// viewDefinitionsEqual reports whether x and y are equivalent.
func viewDefinitionsEqual(x, y *viewDefinition) bool {
	if (x.workspaceModFilesErr == nil) != (y.workspaceModFilesErr == nil) {
		return false
	}
	if x.workspaceModFilesErr != nil {
		if x.workspaceModFilesErr.Error() != y.workspaceModFilesErr.Error() {
			return false
		}
	} else if !moremaps.SameKeys(x.workspaceModFiles, y.workspaceModFiles) {
		return false
	}
	if len(x.envOverlay) != len(y.envOverlay) {
		return false
	}
	for i, xv := range x.envOverlay {
		if xv != y.envOverlay[i] {
			return false
		}
	}
	return x.folder == y.folder &&
		x.typ == y.typ &&
		x.root == y.root &&
		x.gomod == y.gomod &&
		x.gowork == y.gowork
}

// A ViewType describes how we load package information for a view.
//
// This is used for constructing the go/packages.Load query, and for
// interpreting missing packages, imports, or errors.
//
// See the documentation for individual ViewType values for details.
type ViewType int

const (
	// GoPackagesDriverView is a view with a non-empty GOPACKAGESDRIVER
	// environment variable.
	//
	// Load: ./... from the workspace folder.
	GoPackagesDriverView ViewType = iota

	// GOPATHView is a view in GOPATH mode.
	//
	// I.e. in GOPATH, with GO111MODULE=off, or GO111MODULE=auto with no
	// go.mod file.
	//
	// Load: ./... from the workspace folder.
	GOPATHView

	// GoModView is a view in module mode with a single Go module.
	//
	// Load: <modulePath>/... from the module root.
	GoModView

	// GoWorkView is a view in module mode with a go.work file.
	//
	// Load: <modulePath>/... from the workspace folder, for each module.
	GoWorkView

	// An AdHocView is a collection of files in a given directory, not in GOPATH
	// or a module.
	//
	// Load: . from the workspace folder.
	AdHocView
)

func (t ViewType) String() string {
	switch t {
	case GoPackagesDriverView:
		return "GoPackagesDriver"
	case GOPATHView:
		return "GOPATH"
	case GoModView:
		return "GoMod"
	case GoWorkView:
		return "GoWork"
	case AdHocView:
		return "AdHoc"
	default:
		return "Unknown"
	}
}

// usesModules reports whether the view uses Go modules.
func (typ ViewType) usesModules() bool {
	switch typ {
	case GoModView, GoWorkView:
		return true
	default:
		return false
	}
}

// ID returns the unique ID of this View.
func (v *View) ID() string { return v.id }

// GoCommandRunner returns the shared gocommand.Runner for this view.
func (v *View) GoCommandRunner() *gocommand.Runner {
	return v.gocmdRunner
}

// Folder returns the folder at the base of this view.
func (v *View) Folder() *Folder {
	return v.folder
}

// Env returns the environment to use for running go commands in this view.
func (v *View) Env() []string {
	return slices.Concat(
		os.Environ(),
		v.folder.Options.EnvSlice(),
		[]string{"GO111MODULE=" + v.adjustedGO111MODULE()},
		v.EnvOverlay(),
	)
}

// ModcacheIndex returns the module cache index
func (v *View) ModcacheIndex() (*modindex.Index, error) {
	return v.modcacheState.getIndex()
}

// UpdateFolders updates the set of views for the new folders.
//
// Calling this causes each view to be reinitialized.
func (s *Session) UpdateFolders(ctx context.Context, newFolders []*Folder) error {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	overlays := s.Overlays()
	var openFiles []protocol.DocumentURI
	for _, o := range overlays {
		openFiles = append(openFiles, o.URI())
	}

	defs, err := selectViewDefs(ctx, s, newFolders, openFiles)
	if err != nil {
		return err
	}
	var newViews []*View
	for _, def := range defs {
		v, _, release := s.createView(ctx, def)
		release()
		newViews = append(newViews, v)
	}
	for _, v := range s.views {
		v.shutdown()
	}
	s.views = newViews
	return nil
}

// RunProcessEnvFunc runs fn with the process env for this snapshot's view.
// Note: the process env contains cached module and filesystem state.
func (s *Snapshot) RunProcessEnvFunc(ctx context.Context, fn func(context.Context, *imports.Options) error) error {
	return s.view.importsState.runProcessEnvFunc(ctx, s, fn)
}

// separated out from its sole use in locateTemplateFiles for testability
func fileHasExtension(path string, suffixes []string) bool {
	ext := filepath.Ext(path)
	if ext != "" && ext[0] == '.' {
		ext = ext[1:]
	}
	for _, s := range suffixes {
		if s != "" && ext == s {
			return true
		}
	}
	return false
}

// locateTemplateFiles ensures that the snapshot has mapped template files
// within the workspace folder.
func (s *Snapshot) locateTemplateFiles(ctx context.Context) {
	suffixes := s.Options().TemplateExtensions
	if len(suffixes) == 0 {
		return
	}

	searched := 0
	filterFunc := s.view.filterFunc()
	err := filepath.WalkDir(s.view.folder.Dir.Path(), func(path string, entry os.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if entry.IsDir() {
			return nil
		}
		if fileLimit > 0 && searched > fileLimit {
			return errExhausted
		}
		searched++
		if !fileHasExtension(path, suffixes) {
			return nil
		}
		uri := protocol.URIFromPath(path)
		if filterFunc(uri) {
			return nil
		}
		// Get the file in order to include it in the snapshot.
		// TODO(golang/go#57558): it is fundamentally broken to track files in this
		// way; we may lose them if configuration or layout changes cause a view to
		// be recreated.
		//
		// Furthermore, this operation must ignore errors, including context
		// cancellation, or risk leaving the snapshot in an undefined state.
		s.ReadFile(ctx, uri)
		return nil
	})
	if err != nil {
		event.Error(ctx, "searching for template files failed", err)
	}
}

// filterFunc returns a func that reports whether uri is filtered by the currently configured
// directoryFilters.
func (v *View) filterFunc() func(protocol.DocumentURI) bool {
	v.filterFuncOnce.Do(func() {
		folderDir := v.folder.Dir.Path()
		gomodcache := v.folder.Env.GOMODCACHE
		var filters []string
		filters = append(filters, v.folder.Options.DirectoryFilters...)
		if pref, ok := strings.CutPrefix(gomodcache, folderDir); ok {
			modcacheFilter := "-" + strings.TrimPrefix(filepath.ToSlash(pref), "/")
			filters = append(filters, modcacheFilter)
		}
		pathIncluded := PathIncludeFunc(filters)
		v._filterFunc = func(uri protocol.DocumentURI) bool {
			// Only filter relative to the configured root directory.
			if pathutil.InDir(folderDir, uri.Path()) {
				return relPathExcludedByFilter(strings.TrimPrefix(uri.Path(), folderDir), pathIncluded)
			}
			return false
		}
	})
	return v._filterFunc
}

// shutdown releases resources associated with the view.
func (v *View) shutdown() {
	// Cancel the initial workspace load if it is still running.
	v.cancelInitialWorkspaceLoad()
	v.importsState.stopTimer()
	if v.modcacheState != nil {
		v.modcacheState.stopTimer()
	}

	v.snapshotMu.Lock()
	if v.snapshot != nil {
		v.snapshot.cancel()
		v.snapshot.decref()
		v.snapshot = nil
	}
	v.snapshotMu.Unlock()
}

// ScanImports scans the module cache synchronously.
// For use in tests.
func (v *View) ScanImports() {
	gomodcache := v.folder.Env.GOMODCACHE
	dirCache := v.importsState.modCache.dirCache(gomodcache)
	imports.ScanModuleCache(gomodcache, dirCache, log.Printf)
}

// IgnoredFile reports if a file would be ignored by a `go list` of the whole
// workspace.
//
// While go list ./... skips directories starting with '.', '_', or 'testdata',
// gopls may still load them via file queries. Explicitly filter them out.
func (s *Snapshot) IgnoredFile(uri protocol.DocumentURI) bool {
	// Fast path: if uri doesn't contain '.', '_', or 'testdata', it is not
	// possible that it is ignored.
	{
		uriStr := string(uri)
		if !strings.Contains(uriStr, ".") && !strings.Contains(uriStr, "_") && !strings.Contains(uriStr, "testdata") {
			return false
		}
	}

	return s.view.ignoreFilter.ignored(uri.Path())
}

// An ignoreFilter implements go list's exclusion rules via its 'ignored' method.
type ignoreFilter struct {
	prefixes []string // root dirs, ending in filepath.Separator
}

// newIgnoreFilter returns a new ignoreFilter implementing exclusion rules
// relative to the provided directories.
func newIgnoreFilter(dirs []string) *ignoreFilter {
	f := new(ignoreFilter)
	for _, d := range dirs {
		f.prefixes = append(f.prefixes, filepath.Clean(d)+string(filepath.Separator))
	}
	return f
}

func (f *ignoreFilter) ignored(filename string) bool {
	for _, prefix := range f.prefixes {
		if suffix, ok := strings.CutPrefix(filename, prefix); ok {
			if checkIgnored(suffix) {
				return true
			}
		}
	}
	return false
}

// checkIgnored implements go list's exclusion rules.
// Quoting “go help list”:
//
//	Directory and file names that begin with "." or "_" are ignored
//	by the go tool, as are directories named "testdata".
func checkIgnored(suffix string) bool {
	// Note: this could be further optimized by writing a HasSegment helper, a
	// segment-boundary respecting variant of strings.Contains.
	for component := range strings.SplitSeq(suffix, string(filepath.Separator)) {
		if len(component) == 0 {
			continue
		}
		if component[0] == '.' || component[0] == '_' || component == "testdata" {
			return true
		}
	}
	return false
}

// Snapshot returns the current snapshot for the view, and a
// release function that must be called when the Snapshot is
// no longer needed.
//
// The resulting error is non-nil if and only if the view is shut down, in
// which case the resulting release function will also be nil.
func (v *View) Snapshot() (*Snapshot, func(), error) {
	v.snapshotMu.Lock()
	defer v.snapshotMu.Unlock()
	if v.snapshot == nil {
		return nil, nil, errors.New("view is shutdown")
	}
	return v.snapshot, v.snapshot.Acquire(), nil
}

// initialize loads the metadata (and currently, file contents, due to
// golang/go#57558) for the main package query of the View, which depends on
// the view type (see ViewType). If s.initialized is already true, initialize
// is a no op.
//
// The first attempt--which populates the first snapshot for a new view--must
// be allowed to run to completion without being cancelled.
//
// Subsequent attempts are triggered by conditions where gopls can't enumerate
// specific packages that require reloading, such as a change to a go.mod file.
// These attempts may be cancelled, and then retried by a later call.
//
// Postcondition: if ctx was not cancelled, s.initialized is true, s.initialErr
// holds the error resulting from initialization, if any, and s.metadata holds
// the resulting metadata graph.
func (s *Snapshot) initialize(ctx context.Context, firstAttempt bool) {
	// Acquire initializationSema, which is
	// (in effect) a mutex with a timeout.
	select {
	case <-ctx.Done():
		return
	case s.view.initializationSema <- struct{}{}:
	}

	defer func() {
		<-s.view.initializationSema
	}()

	s.mu.Lock()
	initialized := s.initialized
	s.mu.Unlock()

	if initialized {
		return
	}

	defer func() {
		if firstAttempt {
			close(s.view.initialWorkspaceLoad)
		}
	}()

	// TODO(rFindley): we should only locate template files on the first attempt,
	// or guard it via a different mechanism.
	s.locateTemplateFiles(ctx)

	// Collect module paths to load by parsing go.mod files. If a module fails to
	// parse, capture the parsing failure as a critical diagnostic.
	var scopes []loadScope           // scopes to load
	var modDiagnostics []*Diagnostic // diagnostics for broken go.mod files
	addError := func(uri protocol.DocumentURI, err error) {
		modDiagnostics = append(modDiagnostics, &Diagnostic{
			URI:      uri,
			Severity: protocol.SeverityError,
			Source:   ListError,
			Message:  err.Error(),
		})
	}

	if len(s.view.workspaceModFiles) > 0 {
		for modURI := range s.view.workspaceModFiles {
			// Verify that the modfile is valid before trying to load it.
			//
			// TODO(rfindley): now that we no longer need to parse the modfile in
			// order to load scope, we could move these diagnostics to a more general
			// location where we diagnose problems with modfiles or the workspace.
			//
			// Be careful not to add context cancellation errors as critical module
			// errors.
			fh, err := s.ReadFile(ctx, modURI)
			if err != nil {
				if ctx.Err() != nil {
					return
				}
				addError(modURI, err)
				continue
			}
			parsed, err := s.ParseMod(ctx, fh)
			if err != nil {
				if ctx.Err() != nil {
					return
				}
				addError(modURI, err)
				continue
			}
			if parsed.File == nil || parsed.File.Module == nil {
				addError(modURI, fmt.Errorf("no module path for %s", modURI))
				continue
			}
			// Previously, we loaded <modulepath>/... for each module path, but that
			// is actually incorrect when the pattern may match packages in more than
			// one module. See golang/go#59458 for more details.
			scopes = append(scopes, moduleLoadScope{dir: modURI.DirPath(), modulePath: parsed.File.Module.Mod.Path})
		}
	} else {
		scopes = append(scopes, viewLoadScope{})
	}

	// If we're loading anything, ensure we also load builtin,
	// since it provides fake definitions (and documentation)
	// for types like int that are used everywhere.
	if len(scopes) > 0 {
		scopes = append(scopes, packageLoadScope("builtin"))
	}
	loadErr := s.load(ctx, NetworkOK, scopes...)

	// A failure is retryable if it may have been due to context cancellation,
	// and this is not the initial workspace load (firstAttempt==true).
	//
	// The IWL runs on a detached context with a long (~10m) timeout, so
	// if the context was canceled we consider loading to have failed
	// permanently.
	if loadErr != nil && ctx.Err() != nil && !firstAttempt {
		return
	}

	var initialErr *InitializationError
	switch {
	case loadErr != nil && ctx.Err() != nil:
		event.Error(ctx, fmt.Sprintf("initial workspace load: %v", loadErr), loadErr)
		initialErr = &InitializationError{
			MainError: loadErr,
		}
	case loadErr != nil:
		event.Error(ctx, "initial workspace load failed", loadErr)
		extractedDiags := s.extractGoCommandErrors(ctx, loadErr)
		initialErr = &InitializationError{
			MainError:   loadErr,
			Diagnostics: moremaps.Group(extractedDiags, byURI),
		}
	case s.view.workspaceModFilesErr != nil:
		initialErr = &InitializationError{
			MainError: s.view.workspaceModFilesErr,
		}
	case len(modDiagnostics) > 0:
		initialErr = &InitializationError{
			MainError: errors.New(modDiagnostics[0].Message),
		}
	}

	s.mu.Lock()
	defer s.mu.Unlock()

	s.initialized = true
	s.initialErr = initialErr
}

// A StateChange describes external state changes that may affect a snapshot.
//
// By far the most common of these is a change to file state, but a query of
// module upgrade information or vulnerabilities also affects gopls' behavior.
type StateChange struct {
	Modifications      []file.Modification // if set, the raw modifications originating this change
	Files              map[protocol.DocumentURI]file.Handle
	ModuleUpgrades     map[protocol.DocumentURI]map[string]string
	Vulns              map[protocol.DocumentURI]*vulncheck.Result
	CompilerOptDetails map[protocol.DocumentURI]bool // package directory -> whether or not we want details
}

// InvalidateView processes the provided state change, invalidating any derived
// results that depend on the changed state.
//
// The resulting snapshot is non-nil, representing the outcome of the state
// change. The second result is a function that must be called to release the
// snapshot when the snapshot is no longer needed.
//
// An error is returned if the given view is no longer active in the session.
func (s *Session) InvalidateView(ctx context.Context, view *View, changed StateChange) (*Snapshot, func(), error) {
	s.viewMu.Lock()
	defer s.viewMu.Unlock()

	if !slices.Contains(s.views, view) {
		return nil, nil, fmt.Errorf("view is no longer active")
	}
	snapshot, release, _ := s.invalidateViewLocked(ctx, view, changed)
	return snapshot, release, nil
}

// invalidateViewLocked invalidates the content of the given view.
// (See [Session.InvalidateView]).
//
// The resulting bool reports whether the View needs to be re-diagnosed.
// (See [Snapshot.clone]).
//
// s.viewMu must be held while calling this method.
func (s *Session) invalidateViewLocked(ctx context.Context, v *View, changed StateChange) (*Snapshot, func(), bool) {
	// Detach the context so that content invalidation cannot be canceled.
	ctx = xcontext.Detach(ctx)

	// This should be the only time we hold the view's snapshot lock for any period of time.
	v.snapshotMu.Lock()
	defer v.snapshotMu.Unlock()

	prevSnapshot := v.snapshot

	if prevSnapshot == nil {
		panic("invalidateContent called after shutdown")
	}

	// Cancel all still-running previous requests, since they would be
	// operating on stale data.
	prevSnapshot.cancel()

	// Do not clone a snapshot until its view has finished initializing.
	//
	// TODO(rfindley): shouldn't we do this before canceling?
	prevSnapshot.AwaitInitialized(ctx)

	var needsDiagnosis bool
	s.snapshotWG.Add(1)
	v.snapshot, needsDiagnosis = prevSnapshot.clone(ctx, v.baseCtx, changed, s.snapshotWG.Done)

	// Remove the initial reference created when prevSnapshot was created.
	prevSnapshot.decref()

	// Return a second lease to the caller.
	return v.snapshot, v.snapshot.Acquire(), needsDiagnosis
}

// defineView computes the view definition for the provided workspace folder
// and URI.
//
// If forURI is non-empty, this view should be the best view including forURI.
// Otherwise, it is the default view for the folder.
//
// defineView may return an error if the context is cancelled, or the
// workspace folder path is invalid.
//
// Note: keep this function in sync with [RelevantViews].
//
// TODO(rfindley): we should be able to remove the error return, as
// findModules is going away, and all other I/O is memoized.
//
// TODO(rfindley): pass in a narrower interface for the file.Source
// (e.g. fileExists func(DocumentURI) bool) to make clear that this
// process depends only on directory information, not file contents.
func defineView(ctx context.Context, fs file.Source, folder *Folder, forFile file.Handle) (*viewDefinition, error) {
	if err := checkPathValid(folder.Dir.Path()); err != nil {
		return nil, fmt.Errorf("invalid workspace folder path: %w; check that the spelling of the configured workspace folder path agrees with the spelling reported by the operating system", err)
	}
	dir := folder.Dir.Path()
	if forFile != nil {
		dir = forFile.URI().DirPath()
	}

	def := new(viewDefinition)
	def.folder = folder

	if forFile != nil && fileKind(forFile) == file.Go {
		// If the file has GOOS/GOARCH build constraints that
		// don't match the folder's environment (which comes from
		// 'go env' in the folder, plus user options),
		// add those constraints to the viewDefinition's environment.

		// Content trimming is nontrivial, so do this outside of the loop below.
		// Keep this in sync with [RelevantViews].
		path := forFile.URI().Path()
		if content, err := forFile.Content(); err == nil {
			// Note the err == nil condition above: by convention a non-existent file
			// does not have any constraints. See the related note in [RelevantViews]: this
			// choice of behavior shouldn't actually matter. In this case, we should
			// only call defineView with Overlays, which always have content.
			content = trimContentForPortMatch(content)
			viewPort := port{def.folder.Env.GOOS, def.folder.Env.GOARCH}
			if !viewPort.matches(path, content) {
				for _, p := range preferredPorts {
					if p.matches(path, content) {
						if def.envOverlay == nil {
							def.envOverlay = make(map[string]string)
						}
						def.envOverlay["GOOS"] = p.GOOS
						def.envOverlay["GOARCH"] = p.GOARCH
						break
					}
				}
			}
		}
	}

	var err error
	dirURI := protocol.URIFromPath(dir)
	goworkFromEnv := false
	if folder.Env.ExplicitGOWORK != "off" && folder.Env.ExplicitGOWORK != "" {
		goworkFromEnv = true
		def.gowork = protocol.URIFromPath(folder.Env.ExplicitGOWORK)
	} else {
		def.gowork, err = findRootPattern(ctx, dirURI, "go.work", fs)
		if err != nil {
			return nil, err
		}
	}

	// When deriving the best view for a given file, we only want to search
	// up the directory hierarchy for modfiles.
	def.gomod, err = findRootPattern(ctx, dirURI, "go.mod", fs)
	if err != nil {
		return nil, err
	}

	// Determine how we load and where to load package information for this view
	//
	// Specifically, set
	//  - def.typ
	//  - def.root
	//  - def.workspaceModFiles, and
	//  - def.envOverlay.

	// If GOPACKAGESDRIVER is set it takes precedence.
	if def.folder.Env.EffectiveGOPACKAGESDRIVER != "" {
		def.typ = GoPackagesDriverView
		def.root = dirURI
		return def, nil
	}

	// From go.dev/ref/mod, module mode is active if GO111MODULE=on, or
	// GO111MODULE=auto or "" and we are inside a module or have a GOWORK value.
	// But gopls is less strict, allowing GOPATH mode if GO111MODULE="", and
	// AdHoc views if no module is found.

	// gomodWorkspace is a helper to compute the correct set of workspace
	// modfiles for a go.mod file, based on folder options.
	gomodWorkspace := func() map[protocol.DocumentURI]unit {
		modFiles := map[protocol.DocumentURI]struct{}{def.gomod: {}}
		if folder.Options.IncludeReplaceInWorkspace {
			includingReplace, err := goModModules(ctx, def.gomod, fs)
			if err == nil {
				modFiles = includingReplace
			} else {
				// If the go.mod file fails to parse, we don't know anything about
				// replace directives, so fall back to a view of just the root module.
			}
		}
		return modFiles
	}

	// Prefer a go.work file if it is available and contains the module relevant
	// to forURI.
	if def.adjustedGO111MODULE() != "off" && folder.Env.ExplicitGOWORK != "off" && def.gowork != "" {
		def.typ = GoWorkView
		if goworkFromEnv {
			// The go.work file could be anywhere, which can lead to confusing error
			// messages.
			def.root = dirURI
		} else {
			// The go.work file could be anywhere, which can lead to confusing error
			def.root = def.gowork.Dir()
		}
		def.workspaceModFiles, def.workspaceModFilesErr = goWorkModules(ctx, def.gowork, fs)

		// If forURI is in a module but that module is not
		// included in the go.work file, use a go.mod view with GOWORK=off.
		if forFile != nil && def.workspaceModFilesErr == nil && def.gomod != "" {
			if _, ok := def.workspaceModFiles[def.gomod]; !ok {
				def.typ = GoModView
				def.root = def.gomod.Dir()
				def.workspaceModFiles = gomodWorkspace()
				if def.envOverlay == nil {
					def.envOverlay = make(map[string]string)
				}
				def.envOverlay["GOWORK"] = "off"
			}
		}
		return def, nil
	}

	// Otherwise, use the active module, if in module mode.
	//
	// Note, we could override GO111MODULE here via envOverlay if we wanted to
	// support the case where someone opens a module with GO111MODULE=off. But
	// that is probably not worth worrying about (at this point, folks probably
	// shouldn't be setting GO111MODULE).
	if def.adjustedGO111MODULE() != "off" && def.gomod != "" {
		def.typ = GoModView
		def.root = def.gomod.Dir()
		def.workspaceModFiles = gomodWorkspace()
		return def, nil
	}

	// Check if the workspace is within any GOPATH directory.
	inGOPATH := false
	for _, gp := range filepath.SplitList(folder.Env.GOPATH) {
		if pathutil.InDir(filepath.Join(gp, "src"), dir) {
			inGOPATH = true
			break
		}
	}
	if def.adjustedGO111MODULE() != "on" && inGOPATH {
		def.typ = GOPATHView
		def.root = dirURI
		return def, nil
	}

	// We're not in a workspace, module, or GOPATH, so have no better choice than
	// an ad-hoc view.
	def.typ = AdHocView
	def.root = dirURI
	return def, nil
}

// FetchGoEnv queries the environment and Go command to collect environment
// variables necessary for the workspace folder.
func FetchGoEnv(ctx context.Context, folder protocol.DocumentURI, opts *settings.Options) (*GoEnv, error) {
	dir := folder.Path()
	// All of the go commands invoked here should be fast. No need to share a
	// runner with other operations.
	runner := new(gocommand.Runner)
	inv := gocommand.Invocation{
		WorkingDir: dir,
		Env:        opts.EnvSlice(),
	}

	var (
		env = new(GoEnv)
		err error
	)
	envvars := map[string]*string{
		"GOOS":        &env.GOOS,
		"GOARCH":      &env.GOARCH,
		"GOCACHE":     &env.GOCACHE,
		"GOPATH":      &env.GOPATH,
		"GOPRIVATE":   &env.GOPRIVATE,
		"GOMODCACHE":  &env.GOMODCACHE,
		"GOFLAGS":     &env.GOFLAGS,
		"GO111MODULE": &env.GO111MODULE,
		"GOTOOLCHAIN": &env.GOTOOLCHAIN,
		"GOROOT":      &env.GOROOT,
	}
	if err := loadGoEnv(ctx, dir, opts.EnvSlice(), runner, envvars); err != nil {
		return nil, err
	}

	env.GoVersion, err = gocommand.GoVersion(ctx, inv, runner)
	if err != nil {
		return nil, err
	}
	env.GoVersionOutput, err = gocommand.GoVersionOutput(ctx, inv, runner)
	if err != nil {
		return nil, err
	}

	// The value of GOPACKAGESDRIVER is not returned through the go command.
	if driver, ok := opts.Env["GOPACKAGESDRIVER"]; ok {
		if driver != "off" {
			env.EffectiveGOPACKAGESDRIVER = driver
		}
	} else if driver := os.Getenv("GOPACKAGESDRIVER"); driver != "off" {
		env.EffectiveGOPACKAGESDRIVER = driver
		// A user may also have a gopackagesdriver binary on their machine, which
		// works the same way as setting GOPACKAGESDRIVER.
		//
		// TODO(rfindley): remove this call to LookPath. We should not support this
		// undocumented method of setting GOPACKAGESDRIVER.
		if env.EffectiveGOPACKAGESDRIVER == "" {
			tool, err := exec.LookPath("gopackagesdriver")
			if err == nil && tool != "" {
				env.EffectiveGOPACKAGESDRIVER = tool
			}
		}
	}

	// While GOWORK is available through the Go command, we want to differentiate
	// between an explicit GOWORK value and one which is implicit from the file
	// system. The former doesn't change unless the environment changes.
	if gowork, ok := opts.Env["GOWORK"]; ok {
		env.ExplicitGOWORK = gowork
	} else {
		env.ExplicitGOWORK = os.Getenv("GOWORK")
	}
	return env, nil
}

// loadGoEnv loads `go env` values into the provided map, keyed by Go variable
// name.
func loadGoEnv(ctx context.Context, dir string, configEnv []string, runner *gocommand.Runner, vars map[string]*string) error {
	// We can save ~200 ms by requesting only the variables we care about.
	args := []string{"-json"}
	for k := range vars {
		args = append(args, k)
	}

	inv := gocommand.Invocation{
		Verb:       "env",
		Args:       args,
		Env:        configEnv,
		WorkingDir: dir,
	}
	stdout, err := runner.Run(ctx, inv)
	if err != nil {
		return err
	}
	envMap := make(map[string]string)
	if err := json.Unmarshal(stdout.Bytes(), &envMap); err != nil {
		return fmt.Errorf("internal error unmarshaling JSON from 'go env': %w", err)
	}
	for key, ptr := range vars {
		*ptr = envMap[key]
	}

	return nil
}

// findRootPattern looks for files with the given basename in dir or any parent
// directory of dir, using the provided FileSource. It returns the first match,
// starting from dir and search parents.
//
// The resulting string is either the file path of a matching file with the
// given basename, or "" if none was found.
//
// findRootPattern only returns an error in the case of context cancellation.
func findRootPattern(ctx context.Context, dirURI protocol.DocumentURI, basename string, fs file.Source) (protocol.DocumentURI, error) {
	dir := dirURI.Path()
	for dir != "" {
		target := filepath.Join(dir, basename)
		uri := protocol.URIFromPath(target)
		fh, err := fs.ReadFile(ctx, uri)
		if err != nil {
			return "", err // context cancelled
		}
		if fileExists(fh) {
			return uri, nil
		}
		// Trailing separators must be trimmed, otherwise filepath.Split is a noop.
		next, _ := filepath.Split(strings.TrimRight(dir, string(filepath.Separator)))
		if next == dir {
			break
		}
		dir = next
	}
	return "", nil
}

// checkPathValid performs an OS-specific path validity check. The
// implementation varies for filesystems that are case-insensitive
// (e.g. macOS, Windows), and for those that disallow certain file
// names (e.g. path segments ending with a period on Windows, or
// reserved names such as "com"; see
// https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file).
var checkPathValid = defaultCheckPathValid

// CheckPathValid checks whether a directory is suitable as a workspace folder.
func CheckPathValid(dir string) error { return checkPathValid(dir) }

func defaultCheckPathValid(path string) error {
	return nil
}

// IsGoPrivatePath reports whether target is a private import path, as identified
// by the GOPRIVATE environment variable.
func (s *Snapshot) IsGoPrivatePath(target string) bool {
	return globsMatchPath(s.view.folder.Env.GOPRIVATE, target)
}

// ModuleUpgrades returns known module upgrades for the dependencies of
// modfile.
func (s *Snapshot) ModuleUpgrades(modfile protocol.DocumentURI) map[string]string {
	s.mu.Lock()
	defer s.mu.Unlock()
	upgrades := map[string]string{}
	orig, _ := s.moduleUpgrades.Get(modfile)
	maps.Copy(upgrades, orig)
	return upgrades
}

// MaxGovulncheckResultsAge defines the maximum vulnerability age considered
// valid by gopls.
//
// Mutable for testing.
var MaxGovulncheckResultAge = 1 * time.Hour

// Vulnerabilities returns known vulnerabilities for the given modfile.
//
// Results more than an hour old are excluded.
//
// TODO(suzmue): replace command.Vuln with a different type, maybe
// https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck/govulnchecklib#Summary?
//
// TODO(rfindley): move to snapshot.go
func (s *Snapshot) Vulnerabilities(modfiles ...protocol.DocumentURI) map[protocol.DocumentURI]*vulncheck.Result {
	m := make(map[protocol.DocumentURI]*vulncheck.Result)
	now := time.Now()

	s.mu.Lock()
	defer s.mu.Unlock()

	if len(modfiles) == 0 { // empty means all modfiles
		modfiles = slices.Collect(s.vulns.Keys())
	}
	for _, modfile := range modfiles {
		vuln, _ := s.vulns.Get(modfile)
		if vuln != nil && now.Sub(vuln.AsOf) > MaxGovulncheckResultAge {
			vuln = nil
		}
		m[modfile] = vuln
	}
	return m
}

// GoVersion returns the effective release Go version (the X in go1.X) for this
// view.
func (v *View) GoVersion() int {
	return v.folder.Env.GoVersion
}

// GoVersionString returns the effective Go version string for this view.
//
// Unlike [GoVersion], this encodes the minor version and commit hash information.
func (v *View) GoVersionString() string {
	return gocommand.ParseGoVersionOutput(v.folder.Env.GoVersionOutput)
}

// GoVersionString is temporarily available from the snapshot.
//
// TODO(rfindley): refactor so that this method is not necessary.
func (s *Snapshot) GoVersionString() string {
	return s.view.GoVersionString()
}

// Copied from
// https://cs.opensource.google/go/go/+/master:src/cmd/go/internal/str/path.go;l=58;drc=2910c5b4a01a573ebc97744890a07c1a3122c67a
func globsMatchPath(globs, target string) bool {
	for globs != "" {
		// Extract next non-empty glob in comma-separated list.
		var glob string
		if i := strings.Index(globs, ","); i >= 0 {
			glob, globs = globs[:i], globs[i+1:]
		} else {
			glob, globs = globs, ""
		}
		if glob == "" {
			continue
		}

		// A glob with N+1 path elements (N slashes) needs to be matched
		// against the first N+1 path elements of target,
		// which end just before the N+1'th slash.
		n := strings.Count(glob, "/")
		prefix := target
		// Walk target, counting slashes, truncating at the N+1'th slash.
		for i := range len(target) {
			if target[i] == '/' {
				if n == 0 {
					prefix = target[:i]
					break
				}
				n--
			}
		}
		if n > 0 {
			// Not enough prefix elements.
			continue
		}
		matched, _ := path.Match(glob, prefix)
		if matched {
			return true
		}
	}
	return false
}

// TODO(rfindley): clean up the redundancy of allFilesExcluded,
// pathExcludedByFilterFunc, pathExcludedByFilter, view.filterFunc...
func allFilesExcluded(files []string, filterFunc func(protocol.DocumentURI) bool) bool {
	for _, f := range files {
		uri := protocol.URIFromPath(f)
		if !filterFunc(uri) {
			return false
		}
	}
	return true
}

func relPathExcludedByFilter(path string, pathIncluded func(string) bool) bool {
	path = strings.TrimPrefix(filepath.ToSlash(path), "/")
	return !pathIncluded(path)
}


================================================
FILE: gopls/internal/cache/view_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package cache

import (
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

func TestCaseInsensitiveFilesystem(t *testing.T) {
	base := t.TempDir()

	inner := filepath.Join(base, "a/B/c/DEFgh")
	if err := os.MkdirAll(inner, 0777); err != nil {
		t.Fatal(err)
	}
	file := filepath.Join(inner, "f.go")
	if err := os.WriteFile(file, []byte("hi"), 0777); err != nil {
		t.Fatal(err)
	}
	if _, err := os.Stat(filepath.Join(inner, "F.go")); err != nil {
		t.Skip("filesystem is case-sensitive")
	}

	tests := []struct {
		path string
		err  bool
	}{
		{file, false},
		{filepath.Join(inner, "F.go"), true},
		{filepath.Join(base, "a/b/c/defgh/f.go"), true},
	}
	for _, tt := range tests {
		err := checkPathValid(tt.path)
		if err != nil != tt.err {
			t.Errorf("checkPathValid(%q) = %v, wanted error: %v", tt.path, err, tt.err)
		}
	}
}

func TestInVendor(t *testing.T) {
	for _, tt := range []struct {
		path     string
		inVendor bool
	}{
		{"foo/vendor/x.go", false},
		{"foo/vendor/x/x.go", true},
		{"foo/x.go", false},
		{"foo/vendor/foo.txt", false},
		{"foo/vendor/modules.txt", false},
	} {
		if got := inVendor(protocol.URIFromPath(tt.path)); got != tt.inVendor {
			t.Errorf("expected %s inVendor %v, got %v", tt.path, tt.inVendor, got)
		}
	}
}

func TestFilters(t *testing.T) {
	tests := []struct {
		filters  []string
		included []string
		excluded []string
	}{
		{
			included: []string{"x"},
		},
		{
			filters:  []string{"-"},
			excluded: []string{"x", "x/a"},
		},
		{
			filters:  []string{"-x", "+y"},
			included: []string{"y", "y/a", "z"},
			excluded: []string{"x", "x/a"},
		},
		{
			filters:  []string{"-x", "+x/y", "-x/y/z"},
			included: []string{"x/y", "x/y/a", "a"},
			excluded: []string{"x", "x/a", "x/y/z/a"},
		},
		{
			filters:  []string{"+foobar", "-foo"},
			included: []string{"foobar", "foobar/a"},
			excluded: []string{"foo", "foo/a"},
		},
	}

	for _, tt := range tests {
		pathIncluded := PathIncludeFunc(tt.filters)
		for _, inc := range tt.included {
			if relPathExcludedByFilter(inc, pathIncluded) {
				t.Errorf("filters %q excluded %v, wanted included", tt.filters, inc)
			}
		}
		for _, exc := range tt.excluded {
			if !relPathExcludedByFilter(exc, pathIncluded) {
				t.Errorf("filters %q included %v, wanted excluded", tt.filters, exc)
			}
		}
	}
}

func TestSuffixes(t *testing.T) {
	type file struct {
		path string
		want bool
	}
	type cases struct {
		option []string
		files  []file
	}
	tests := []cases{
		{[]string{"tmpl", "gotmpl"}, []file{ // default
			{"foo", false},
			{"foo.tmpl", true},
			{"foo.gotmpl", true},
			{"tmpl", false},
			{"tmpl.go", false}},
		},
		{[]string{"tmpl", "gotmpl", "html", "gohtml"}, []file{
			{"foo.gotmpl", true},
			{"foo.html", true},
			{"foo.gohtml", true},
			{"html", false}},
		},
		{[]string{"tmpl", "gotmpl", ""}, []file{ // possible user mistake
			{"foo.gotmpl", true},
			{"foo.go", false},
			{"foo", false}},
		},
	}
	for _, a := range tests {
		suffixes := a.option
		for _, b := range a.files {
			got := fileHasExtension(b.path, suffixes)
			if got != b.want {
				t.Errorf("got %v, want %v, option %q, file %q (%+v)",
					got, b.want, a.option, b.path, b)
			}
		}
	}
}

func TestIgnoreFilter(t *testing.T) {
	tests := []struct {
		dirs []string
		path string
		want bool
	}{
		{[]string{"a"}, "a/testdata/foo", true},
		{[]string{"a"}, "a/_ignore/foo", true},
		{[]string{"a"}, "a/.ignore/foo", true},
		{[]string{"a"}, "b/testdata/foo", false},
		{[]string{"a"}, "testdata/foo", false},
		{[]string{"a", "b"}, "b/testdata/foo", true},
		{[]string{"a"}, "atestdata/foo", false},
	}

	for _, test := range tests {
		// convert to filepaths, for convenience
		for i, dir := range test.dirs {
			test.dirs[i] = filepath.FromSlash(dir)
		}
		test.path = filepath.FromSlash(test.path)

		f := newIgnoreFilter(test.dirs)
		if got := f.ignored(test.path); got != test.want {
			t.Errorf("newIgnoreFilter(%q).ignore(%q) = %t, want %t", test.dirs, test.path, got, test.want)
		}
	}
}


================================================
FILE: gopls/internal/cache/workspace.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cache

import (
	"context"
	"errors"
	"fmt"
	"path/filepath"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake/glob"
)

// isGoWork reports if uri is a go.work file.
func isGoWork(uri protocol.DocumentURI) bool {
	return uri.Base() == "go.work"
}

// goWorkModules returns the URIs of go.mod files named by the go.work file.
func goWorkModules(ctx context.Context, gowork protocol.DocumentURI, fs file.Source) (map[protocol.DocumentURI]unit, error) {
	fh, err := fs.ReadFile(ctx, gowork)
	if err != nil {
		return nil, err // canceled
	}
	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	filename := gowork.Path()
	dir := filepath.Dir(filename)
	workFile, err := modfile.ParseWork(filename, content, nil)
	if err != nil {
		return nil, fmt.Errorf("parsing go.work: %w", err)
	}
	var usedDirs []string
	for _, use := range workFile.Use {
		usedDirs = append(usedDirs, use.Path)
	}
	return localModFiles(dir, usedDirs), nil
}

// localModFiles builds a set of local go.mod files referenced by
// goWorkOrModPaths, which is a slice of paths as contained in a go.work 'use'
// directive or go.mod 'replace' directive (and which therefore may use either
// '/' or '\' as a path separator).
func localModFiles(relativeTo string, goWorkOrModPaths []string) map[protocol.DocumentURI]unit {
	modFiles := make(map[protocol.DocumentURI]unit)
	for _, path := range goWorkOrModPaths {
		modDir := filepath.FromSlash(path)
		if !filepath.IsAbs(modDir) {
			modDir = filepath.Join(relativeTo, modDir)
		}
		modURI := protocol.URIFromPath(filepath.Join(modDir, "go.mod"))
		modFiles[modURI] = unit{}
	}
	return modFiles
}

// isGoMod reports if uri is a go.mod file.
func isGoMod(uri protocol.DocumentURI) bool {
	return uri.Base() == "go.mod"
}

// isWorkspaceFile reports if uri matches a set of globs defined in workspaceFiles
func isWorkspaceFile(uri protocol.DocumentURI, workspaceFiles []string) bool {
	for _, workspaceFile := range workspaceFiles {
		g, err := glob.Parse(workspaceFile)
		if err != nil {
			continue
		}

		if g.Match(uri.Path()) {
			return true
		}
	}
	return false
}

// goModModules returns the URIs of "workspace" go.mod files defined by a
// go.mod file. This set is defined to be the given go.mod file itself, as well
// as the modfiles of any locally replaced modules in the go.mod file.
func goModModules(ctx context.Context, gomod protocol.DocumentURI, fs file.Source) (map[protocol.DocumentURI]unit, error) {
	fh, err := fs.ReadFile(ctx, gomod)
	if err != nil {
		return nil, err // canceled
	}
	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	filename := gomod.Path()
	dir := filepath.Dir(filename)
	modFile, err := modfile.Parse(filename, content, nil)
	if err != nil {
		return nil, err
	}
	var localReplaces []string
	for _, replace := range modFile.Replace {
		if modfile.IsDirectoryPath(replace.New.Path) {
			localReplaces = append(localReplaces, replace.New.Path)
		}
	}
	modFiles := localModFiles(dir, localReplaces)
	modFiles[gomod] = unit{}
	return modFiles, nil
}

// fileExists reports whether the file has a Content (which may be empty).
// An overlay exists even if it is not reflected in the file system.
func fileExists(fh file.Handle) bool {
	_, err := fh.Content()
	return err == nil
}

// errExhausted is returned by findModules if the file scan limit is reached.
var errExhausted = errors.New("exhausted")

// Limit go.mod search to 1 million files. As a point of reference,
// Kubernetes has 22K files (as of 2020-11-24).
//
// Note: per golang/go#56496, the previous limit of 1M files was too slow, at
// which point this limit was decreased to 100K.
const fileLimit = 100_000


================================================
FILE: gopls/internal/cache/xrefs/xrefs.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package xrefs defines the serializable index of cross-package
// references that is computed during type checking.
//
// See ../references.go for the 'references' query.
package xrefs

import (
	"go/ast"
	"go/types"
	"sort"

	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/frob"
)

// Index constructs a serializable index of outbound cross-references
// for the specified type-checked package.
func Index(files []*parsego.File, pkg *types.Package, info *types.Info) []byte {
	// pkgObjects maps each referenced package Q to a mapping:
	// from each referenced symbol in Q to the ordered list
	// of references to that symbol from this package.
	// A nil types.Object indicates a reference
	// to the package as a whole: an import.
	pkgObjects := make(map[*types.Package]map[types.Object]*gobObject)

	// getObjects returns the object-to-references mapping for a package.
	getObjects := func(pkg *types.Package) map[types.Object]*gobObject {
		objects, ok := pkgObjects[pkg]
		if !ok {
			objects = make(map[types.Object]*gobObject)
			pkgObjects[pkg] = objects
		}
		return objects
	}

	objectpathFor := new(objectpath.Encoder).For

	for fileIndex, pgf := range files {
		for cur := range pgf.Cursor().Preorder((*ast.Ident)(nil), (*ast.ImportSpec)(nil)) {
			switch n := cur.Node().(type) {
			case *ast.Ident:
				// Report a reference for each identifier that
				// uses a symbol exported from another package.
				// (The built-in error.Error method has no package.)
				if n.IsExported() {
					if obj, ok := info.Uses[n]; ok &&
						obj.Pkg() != nil &&
						obj.Pkg() != pkg {

						// For instantiations of generic methods,
						// use the generic object (see issue #60622).
						if fn, ok := obj.(*types.Func); ok {
							obj = fn.Origin()
						}

						objects := getObjects(obj.Pkg())
						gobObj, ok := objects[obj]
						if !ok {
							path, err := objectpathFor(obj)
							if err != nil {
								// Capitalized but not exported
								// (e.g. local const/var/type).
								continue
							}
							gobObj = &gobObject{Path: path}
							objects[obj] = gobObj
						}

						// golang/go#66683: nodes can under/overflow the file.
						// For example, "var _ = x." creates a SelectorExpr(Sel=Ident("_"))
						// that is beyond EOF. (Arguably Ident.Name should be "".)
						if rng, err := pgf.NodeRange(n); err == nil {
							gobObj.Refs = append(gobObj.Refs, gobRef{
								FileIndex: fileIndex,
								Range:     rng,
							})
						}
					}
				}

			case *ast.ImportSpec:
				// Report a reference from each import path
				// string to the imported package.
				pkgname := info.PkgNameOf(n)
				if pkgname == nil {
					continue // missing import
				}
				objects := getObjects(pkgname.Imported())
				gobObj, ok := objects[nil]
				if !ok {
					gobObj = &gobObject{Path: ""}
					objects[nil] = gobObj
				}
				// golang/go#66683: nodes can under/overflow the file.
				if rng, err := pgf.NodeRange(n.Path); err == nil {
					gobObj.Refs = append(gobObj.Refs, gobRef{
						FileIndex: fileIndex,
						Range:     rng,
					})
				} else {
					bug.Reportf("out of bounds import spec %+v", n.Path)
				}
			}
		}
	}

	// Flatten the maps into slices, and sort for determinism.
	var packages []*gobPackage
	for p := range pkgObjects {
		objects := pkgObjects[p]
		gp := &gobPackage{
			PkgPath: metadata.PackagePath(p.Path()),
			Objects: make([]*gobObject, 0, len(objects)),
		}
		for _, gobObj := range objects {
			gp.Objects = append(gp.Objects, gobObj)
		}
		sort.Slice(gp.Objects, func(i, j int) bool {
			return gp.Objects[i].Path < gp.Objects[j].Path
		})
		packages = append(packages, gp)
	}
	sort.Slice(packages, func(i, j int) bool {
		return packages[i].PkgPath < packages[j].PkgPath
	})

	return packageCodec.Encode(packages)
}

// Lookup searches a serialized index produced by an indexPackage
// operation on m, and returns the locations of all references from m
// to any object in the target set. Each object is denoted by a pair
// of (package path, object path).
func Lookup(mp *metadata.Package, data []byte, targets map[metadata.PackagePath]map[objectpath.Path]struct{}) (locs []protocol.Location) {
	var packages []*gobPackage
	packageCodec.Decode(data, &packages)
	for _, gp := range packages {
		if objectSet, ok := targets[gp.PkgPath]; ok {
			for _, gobObj := range gp.Objects {
				if _, ok := objectSet[gobObj.Path]; ok {
					for _, ref := range gobObj.Refs {
						uri := mp.CompiledGoFiles[ref.FileIndex]
						locs = append(locs, protocol.Location{
							URI:   uri,
							Range: ref.Range,
						})
					}
				}
			}
		}
	}

	return locs
}

// -- serialized representation --

// The cross-reference index records the location of all references
// from one package to symbols defined in other packages
// (dependencies). It does not record within-package references.
// The index for package P consists of a list of gopPackage records,
// each enumerating references to symbols defined a single dependency, Q.

// TODO(adonovan): opt: choose a more compact encoding.
// The gobRef.Range field is the obvious place to begin.

// (The name says gob but in fact we use frob.)
var packageCodec = frob.CodecFor[[]*gobPackage]()

// A gobPackage records the set of outgoing references from the index
// package to symbols defined in a dependency package.
type gobPackage struct {
	PkgPath metadata.PackagePath // defining package (Q)
	Objects []*gobObject         // set of Q objects referenced by P
}

// A gobObject records all references to a particular symbol.
type gobObject struct {
	Path objectpath.Path // symbol name within package; "" => import of package itself
	Refs []gobRef        // locations of references within P, in lexical order
}

type gobRef struct {
	FileIndex int            // index of enclosing file within P's CompiledGoFiles
	Range     protocol.Range // source range of reference
}


================================================
FILE: gopls/internal/clonetest/clonetest.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package clonetest provides utility functions for testing Clone operations.
//
// The [NonZero] helper may be used to construct a type in which fields are
// recursively set to a non-zero value. This value can then be cloned, and the
// [ZeroOut] helper can set values stored in the clone to zero, recursively.
// Doing so should not mutate the original.
package clonetest

import (
	"fmt"
	"reflect"
	"slices"
)

// NonZero returns a T set to some appropriate nonzero value:
//   - Values of basic type are set to an arbitrary non-zero value.
//   - Struct fields are set to a non-zero value.
//   - Array indices are set to a non-zero value.
//   - Pointers point to a non-zero value.
//   - Maps and slices are given a non-zero element.
//   - Chan, Func, Interface, UnsafePointer are all unsupported.
//
// NonZero breaks cycles by returning a zero value for recursive types.
func NonZero[T any]() T {
	var x T
	t := reflect.TypeOf(x)
	if t == nil {
		panic("untyped nil")
	}
	v := nonZeroValue(t, nil)
	return v.Interface().(T)
}

// nonZeroValue returns a non-zero, addressable value of the given type.
func nonZeroValue(t reflect.Type, seen []reflect.Type) reflect.Value {
	if slices.Contains(seen, t) {
		// Cycle: return the zero value.
		return reflect.Zero(t)
	}
	seen = append(seen, t)
	v := reflect.New(t).Elem()
	switch t.Kind() {
	case reflect.Bool:
		v.SetBool(true)

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
		v.SetInt(1)

	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr:
		v.SetUint(1)

	case reflect.Float32, reflect.Float64:
		v.SetFloat(1)

	case reflect.Complex64, reflect.Complex128:
		v.SetComplex(1)

	case reflect.Array:
		for i := 0; i < v.Len(); i++ {
			v.Index(i).Set(nonZeroValue(t.Elem(), seen))
		}

	case reflect.Map:
		v2 := reflect.MakeMap(t)
		v2.SetMapIndex(nonZeroValue(t.Key(), seen), nonZeroValue(t.Elem(), seen))
		v.Set(v2)

	case reflect.Pointer:
		v2 := nonZeroValue(t.Elem(), seen)
		v.Set(v2.Addr())

	case reflect.Slice:
		v2 := reflect.Append(v, nonZeroValue(t.Elem(), seen))
		v.Set(v2)

	case reflect.String:
		v.SetString(".")

	case reflect.Struct:
		for i := 0; i < v.NumField(); i++ {
			v.Field(i).Set(nonZeroValue(t.Field(i).Type, seen))
		}

	default: // Chan, Func, Interface, UnsafePointer
		panic(fmt.Sprintf("reflect kind %v not supported", t.Kind()))
	}
	return v
}

// ZeroOut recursively sets values contained in t to zero.
// Values of king Chan, Func, Interface, UnsafePointer are all unsupported.
//
// No attempt is made to handle cyclic values.
func ZeroOut[T any](t *T) {
	v := reflect.ValueOf(t).Elem()
	zeroOutValue(v)
}

func zeroOutValue(v reflect.Value) {
	if v.IsZero() {
		return // nothing to do; this also handles untyped nil values
	}

	switch v.Kind() {
	case reflect.Bool,
		reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64, reflect.Uintptr,
		reflect.Float32, reflect.Float64,
		reflect.Complex64, reflect.Complex128,
		reflect.String:

		v.Set(reflect.Zero(v.Type()))

	case reflect.Array:
		for i := 0; i < v.Len(); i++ {
			zeroOutValue(v.Index(i))
		}

	case reflect.Map:
		iter := v.MapRange()
		for iter.Next() {
			mv := iter.Value()
			if mv.CanAddr() {
				zeroOutValue(mv)
			} else {
				mv = reflect.New(mv.Type()).Elem()
			}
			v.SetMapIndex(iter.Key(), mv)
		}

	case reflect.Pointer:
		zeroOutValue(v.Elem())

	case reflect.Slice:
		for i := 0; i < v.Len(); i++ {
			zeroOutValue(v.Index(i))
		}

	case reflect.Struct:
		for i := 0; i < v.NumField(); i++ {
			zeroOutValue(v.Field(i))
		}

	default:
		panic(fmt.Sprintf("reflect kind %v not supported", v.Kind()))
	}
}


================================================
FILE: gopls/internal/clonetest/clonetest_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package clonetest_test

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/clonetest"
)

func Test(t *testing.T) {
	doTest(t, true, false)
	type B bool
	doTest(t, B(true), false)
	doTest(t, 1, 0)
	doTest(t, int(1), 0)
	doTest(t, int8(1), 0)
	doTest(t, int16(1), 0)
	doTest(t, int32(1), 0)
	doTest(t, int64(1), 0)
	doTest(t, uint(1), 0)
	doTest(t, uint8(1), 0)
	doTest(t, uint16(1), 0)
	doTest(t, uint32(1), 0)
	doTest(t, uint64(1), 0)
	doTest(t, uintptr(1), 0)
	doTest(t, float32(1), 0)
	doTest(t, float64(1), 0)
	doTest(t, complex64(1), 0)
	doTest(t, complex128(1), 0)
	doTest(t, [3]int{1, 1, 1}, [3]int{0, 0, 0})
	doTest(t, ".", "")
	m1, m2 := map[string]int{".": 1}, map[string]int{".": 0}
	doTest(t, m1, m2)
	doTest(t, &m1, &m2)
	doTest(t, []int{1}, []int{0})
	i, j := 1, 0
	doTest(t, &i, &j)
	k, l := &i, &j
	doTest(t, &k, &l)

	s1, s2 := []int{1}, []int{0}
	doTest(t, &s1, &s2)

	type S struct {
		Field int
	}
	doTest(t, S{1}, S{0})

	doTest(t, []*S{{1}}, []*S{{0}})

	// An arbitrary recursive type.
	type LinkedList[T any] struct {
		V    T
		Next *LinkedList[T]
	}
	doTest(t, &LinkedList[int]{V: 1}, &LinkedList[int]{V: 0})
}

// doTest checks that the result of NonZero matches the nonzero argument, and
// that zeroing out that result matches the zero argument.
func doTest[T any](t *testing.T, nonzero, zero T) {
	got := clonetest.NonZero[T]()
	if diff := cmp.Diff(nonzero, got); diff != "" {
		t.Fatalf("NonZero() returned unexpected diff (-want +got):\n%s", diff)
	}
	clonetest.ZeroOut(&got)
	if diff := cmp.Diff(zero, got); diff != "" {
		t.Errorf("ZeroOut() returned unexpected diff (-want +got):\n%s", diff)
	}
}


================================================
FILE: gopls/internal/cmd/call_hierarchy.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// callHierarchy implements the callHierarchy verb for gopls.
type callHierarchy struct {
	app *Application
}

func (c *callHierarchy) Name() string      { return "call_hierarchy" }
func (c *callHierarchy) Parent() string    { return c.app.Name() }
func (c *callHierarchy) Usage() string     { return "<position>" }
func (c *callHierarchy) ShortHelp() string { return "display selected identifier's call hierarchy" }
func (c *callHierarchy) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls call_hierarchy helper/helper.go:8:6
	$ gopls call_hierarchy helper/helper.go:#53
`)
	printFlagDefaults(f)
}

func (c *callHierarchy) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("call_hierarchy expects 1 argument (position)")
	}

	cli, _, err := c.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}

	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}

	p := protocol.CallHierarchyPrepareParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}

	callItems, err := cli.server.PrepareCallHierarchy(ctx, &p)
	if err != nil {
		return err
	}
	if len(callItems) == 0 {
		return fmt.Errorf("function declaration identifier not found at %v", args[0])
	}

	for _, item := range callItems {
		incomingCalls, err := cli.server.IncomingCalls(ctx, &protocol.CallHierarchyIncomingCallsParams{Item: item})
		if err != nil {
			return err
		}
		for i, call := range incomingCalls {
			// From the spec: CallHierarchyIncomingCall.FromRanges is relative to
			// the caller denoted by CallHierarchyIncomingCall.from.
			printString, err := callItemPrintString(ctx, cli, call.From, call.From.URI, call.FromRanges)
			if err != nil {
				return err
			}
			fmt.Printf("caller[%d]: %s\n", i, printString)
		}

		printString, err := callItemPrintString(ctx, cli, item, "", nil)
		if err != nil {
			return err
		}
		fmt.Printf("identifier: %s\n", printString)

		outgoingCalls, err := cli.server.OutgoingCalls(ctx, &protocol.CallHierarchyOutgoingCallsParams{Item: item})
		if err != nil {
			return err
		}
		for i, call := range outgoingCalls {
			// From the spec: CallHierarchyOutgoingCall.FromRanges is the range
			// relative to the caller, e.g the item passed to
			printString, err := callItemPrintString(ctx, cli, call.To, item.URI, call.FromRanges)
			if err != nil {
				return err
			}
			fmt.Printf("callee[%d]: %s\n", i, printString)
		}
	}

	return nil
}

// callItemPrintString returns a protocol.CallHierarchyItem object represented as a string.
// item and call ranges (protocol.Range) are converted to user friendly spans (1-indexed).
func callItemPrintString(ctx context.Context, cli *client, item protocol.CallHierarchyItem, callsURI protocol.DocumentURI, calls []protocol.Range) (string, error) {
	itemFile, err := cli.openFile(ctx, item.URI)
	if err != nil {
		return "", err
	}
	itemSpan, err := itemFile.rangeSpan(item.Range)
	if err != nil {
		return "", err
	}

	var callRanges []string
	if callsURI != "" {
		callsFile, err := cli.openFile(ctx, callsURI)
		if err != nil {
			return "", err
		}
		for _, rng := range calls {
			call, err := callsFile.rangeSpan(rng)
			if err != nil {
				return "", err
			}
			callRange := fmt.Sprintf("%d:%d-%d", call.Start().Line(), call.Start().Column(), call.End().Column())
			callRanges = append(callRanges, callRange)
		}
	}

	printString := fmt.Sprintf("function %s in %v", item.Name, itemSpan)
	if len(calls) > 0 {
		printString = fmt.Sprintf("ranges %s in %s from/to %s", strings.Join(callRanges, ", "), callsURI.Path(), printString)
	}
	return printString, nil
}


================================================
FILE: gopls/internal/cmd/capabilities_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/testenv"
)

// TestCapabilities does some minimal validation of the server's adherence to the LSP.
// The checks in the test are added as changes are made and errors noticed.
func TestCapabilities(t *testing.T) {
	// server.DidOpen fails to obtain metadata without go command (e.g. on wasm).
	testenv.NeedsTool(t, "go")

	tmpDir, err := os.MkdirTemp("", "fake")
	if err != nil {
		t.Fatal(err)
	}
	tmpFile := filepath.Join(tmpDir, "fake.go")
	if err := os.WriteFile(tmpFile, []byte(""), 0775); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(tmpDir, "go.mod"), []byte("module fake\n\ngo 1.12\n"), 0775); err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpDir)

	app := New()
	ctx := context.Background()

	// Initialize the client.
	// (Unlike app.connect, we use minimal Initialize params.)
	client := newClient(app)
	options := settings.DefaultOptions(app.options)
	server := server.New(cache.NewSession(ctx, cache.New(nil)), client, options)
	params := &protocol.ParamInitialize{}
	params.RootURI = protocol.URIFromPath(tmpDir)
	params.Capabilities.Workspace.Configuration = true
	if err := client.initialize(ctx, server, params); err != nil {
		t.Fatal(err)
	}
	defer client.terminate(ctx)

	if err := validateCapabilities(client.initializeResult); err != nil {
		t.Error(err)
	}

	// Open the file on the server side.
	uri := protocol.URIFromPath(tmpFile)
	if err := server.DidOpen(ctx, &protocol.DidOpenTextDocumentParams{
		TextDocument: protocol.TextDocumentItem{
			URI:        uri,
			LanguageID: "go",
			Version:    1,
			Text:       `package main; func main() {};`,
		},
	}); err != nil {
		t.Fatal(err)
	}

	// If we are sending a full text change, the change.Range must be nil.
	// It is not enough for the Change to be empty, as that is ambiguous.
	if err := server.DidChange(ctx, &protocol.DidChangeTextDocumentParams{
		TextDocument: protocol.VersionedTextDocumentIdentifier{
			TextDocumentIdentifier: protocol.TextDocumentIdentifier{
				URI: uri,
			},
			Version: 2,
		},
		ContentChanges: []protocol.TextDocumentContentChangeEvent{
			{
				Range: nil,
				Text:  `package main; func main() { fmt.Println("") }`,
			},
		},
	}); err != nil {
		t.Fatal(err)
	}

	// Send a code action request to validate expected types.
	actions, err := server.CodeAction(ctx, &protocol.CodeActionParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
		Context: protocol.CodeActionContext{
			Only: []protocol.CodeActionKind{protocol.SourceOrganizeImports},
		},
	})
	if err != nil {
		t.Fatal(err)
	}
	for _, action := range actions {
		// Validate that an empty command is sent along with import organization responses.
		if action.Kind == protocol.SourceOrganizeImports && action.Command != nil {
			t.Errorf("unexpected command for import organization")
		}
	}

	if err := server.DidSave(ctx, &protocol.DidSaveTextDocumentParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
		// LSP specifies that a file can be saved with optional text, so this field must be nil.
		Text: nil,
	}); err != nil {
		t.Fatal(err)
	}

	// Send a completion request to validate expected types.
	list, err := server.Completion(ctx, &protocol.CompletionParams{
		TextDocumentPositionParams: protocol.TextDocumentPositionParams{
			TextDocument: protocol.TextDocumentIdentifier{
				URI: uri,
			},
			Range: protocol.Range{
				Start: protocol.Position{
					Line:      0,
					Character: 28,
				},
				End: protocol.Position{
					Line:      0,
					Character: 28,
				},
			},
		},
	})
	if err != nil {
		t.Fatal(err)
	}
	for _, item := range list.Items {
		// All other completion items should have nil commands.
		// An empty command will be treated as a command with the name '' by VS Code.
		// This causes VS Code to report errors to users about invalid commands.
		if item.Command != nil {
			t.Errorf("unexpected command for completion item")
		}
		// The item's TextEdit must be a pointer, as VS Code considers TextEdits
		// that don't contain the cursor position to be invalid.
		var textEdit = item.TextEdit.Value
		switch textEdit.(type) {
		case protocol.TextEdit, protocol.InsertReplaceEdit:
		default:
			t.Errorf("textEdit is not TextEdit nor InsertReplaceEdit, instead it is %T", textEdit)
		}
	}
	if err := server.Shutdown(ctx); err != nil {
		t.Fatal(err)
	}
	if err := server.Exit(ctx); err != nil {
		t.Fatal(err)
	}
}

func validateCapabilities(result *protocol.InitializeResult) error {
	// If the client sends "false" for RenameProvider.PrepareSupport,
	// the server must respond with a boolean.
	if v, ok := result.Capabilities.RenameProvider.(bool); !ok {
		return fmt.Errorf("RenameProvider must be a boolean if PrepareSupport is false (got %T)", v)
	}
	// The same goes for CodeActionKind.ValueSet.
	if v, ok := result.Capabilities.CodeActionProvider.(bool); !ok {
		return fmt.Errorf("CodeActionSupport must be a boolean if CodeActionKind.ValueSet has length 0 (got %T)", v)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/check.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"slices"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
)

// check implements the check verb for gopls.
type check struct {
	app      *Application
	Severity string `flag:"severity" help:"minimum diagnostic severity (hint, info, warning, or error)"`
}

func (c *check) Name() string      { return "check" }
func (c *check) Parent() string    { return c.app.Name() }
func (c *check) Usage() string     { return "<filename>" }
func (c *check) ShortHelp() string { return "show diagnostic results for the specified file" }
func (c *check) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example: show the diagnostic results of this file:

	$ gopls check internal/cmd/check.go
`)
	printFlagDefaults(f)
}

// Run performs the check on the files specified by args and prints the
// results to stdout.
func (c *check) Run(ctx context.Context, args ...string) error {
	severityCutoff := protocol.SeverityWarning
	switch c.Severity {
	case "hint":
		severityCutoff = protocol.SeverityHint
	case "info":
		severityCutoff = protocol.SeverityInformation
	case "warning":
		// default
	case "error":
		severityCutoff = protocol.SeverityError
	default:
		return fmt.Errorf("unrecognized -severity value %q", c.Severity)
	}

	if len(args) == 0 {
		return nil
	}

	// TODO(adonovan): formally, we are required to set this
	// option if we want RelatedInformation, but it appears to
	// have no effect on the server, even though the default is
	// false. Investigate.
	origOptions := c.app.options
	c.app.options = func(opts *settings.Options) {
		if origOptions != nil {
			origOptions(opts)
		}
		opts.RelatedInformationSupported = true
	}

	cli, _, err := c.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	// Open and diagnose the requested files.
	var (
		uris     []protocol.DocumentURI
		checking = make(map[protocol.DocumentURI]*cmdFile)
	)
	for _, arg := range args {
		uri := protocol.URIFromPath(arg)
		uris = append(uris, uri)
		file, err := cli.openFile(ctx, uri)
		if err != nil {
			return err
		}
		checking[uri] = file
	}
	if err := diagnoseFiles(ctx, cli.server, uris); err != nil {
		return err
	}

	// print prints a single element of a diagnostic.
	print := func(uri protocol.DocumentURI, rng protocol.Range, message string) error {
		file, err := cli.openFile(ctx, uri)
		if err != nil {
			return err
		}
		spn, err := file.rangeSpan(rng)
		if err != nil {
			return fmt.Errorf("could not convert position %v for %q", rng, message)
		}
		fmt.Printf("%v: %v\n", spn, message)
		return nil
	}

	for _, file := range checking {
		file.diagnosticsMu.Lock()
		diags := slices.Clone(file.diagnostics)
		file.diagnosticsMu.Unlock()

		for _, diag := range diags {
			if diag.Severity > severityCutoff { // lower severity value => greater severity, counterintuitively
				continue
			}
			if err := print(file.uri, diag.Range, diag.Message); err != nil {
				return err
			}
			for _, rel := range diag.RelatedInformation {
				if err := print(rel.Location.URI, rel.Location.Range, "- "+rel.Message); err != nil {
					return err
				}
			}

		}
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/cmd.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cmd handles the gopls command line.
// It contains a handler for each of the modes, along with all the flag handling
// and the command line output format.
package cmd

import (
	"context"
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"reflect"
	"sort"
	"strings"
	"sync"
	"text/tabwriter"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/browser"
	bugpkg "golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/moreslices"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/tool"
)

// Application is the main application as passed to tool.Main
// It handles the main command line parsing and dispatch to the sub commands.
type Application struct {
	// Core application flags

	// Embed the basic profiling flags supported by the tool package
	tool.Profile

	// We include the server configuration directly for now, so the flags work
	// even without the verb.
	// TODO: Remove this when we stop allowing the serve verb by default.
	Serve Serve

	// the options configuring function to invoke when building a server
	options func(*settings.Options)

	// Support for remote LSP server.
	Remote string `flag:"remote" help:"forward all commands to a remote lsp specified by this flag. With no special prefix, this is assumed to be a TCP address. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. If 'auto', or prefixed by 'auto;', the remote address is automatically resolved based on the executing environment."`

	// Verbose enables verbose logging.
	Verbose bool `flag:"v,verbose" help:"verbose output"`

	// VeryVerbose enables a higher level of verbosity in logging output.
	VeryVerbose bool `flag:"vv,veryverbose" help:"very verbose output"`

	// OTel specifies the OpenTelemetry collector endpoint (e.g. http://localhost:4318).
	OTel string `flag:"otel" help:"export telemetry to specified OpenTelemetry collector address (e.g. http://localhost:4318)"`

	// PrepareOptions is called to update the options when a new view is built.
	// It is primarily to allow the behavior of gopls to be modified by hooks.
	PrepareOptions func(*settings.Options)

	// editFlags holds flags that control how file edit operations
	// are applied, in particular when the server makes an ApplyEdits
	// downcall to the client. Present only for commands that apply edits.
	editFlags *EditFlags
}

// EditFlags defines flags common to {code{action,lens},format,imports,rename}
// that control how edits are applied to the client's files.
//
// The type is exported for flag reflection.
//
// The -write, -diff, and -list flags are orthogonal but any
// of them suppresses the default behavior, which is to print
// the edited file contents.
type EditFlags struct {
	Write    bool `flag:"w,write" help:"write edited content to source files"`
	Preserve bool `flag:"preserve" help:"with -write, make copies of original files"`
	Diff     bool `flag:"d,diff" help:"display diffs instead of edited file content"`
	List     bool `flag:"l,list" help:"display names of edited files"`
}

func (app *Application) verbose() bool {
	return app.Verbose || app.VeryVerbose
}

// New returns a new Application ready to run.
func New() *Application {
	app := &Application{
		Serve: Serve{
			RemoteListenTimeout: 1 * time.Minute,
		},
	}
	app.Serve.app = app
	return app
}

// Name implements tool.Application returning the binary name.
func (app *Application) Name() string { return "gopls" }

// Usage implements tool.Application returning empty extra argument usage.
func (app *Application) Usage() string { return "" }

// ShortHelp implements tool.Application returning the main binary help.
func (app *Application) ShortHelp() string {
	return ""
}

// DetailedHelp implements tool.Application returning the main binary help.
// This includes the short help for all the sub commands.
func (app *Application) DetailedHelp(f *flag.FlagSet) {
	w := tabwriter.NewWriter(f.Output(), 0, 0, 2, ' ', 0)
	defer w.Flush()

	fmt.Fprint(w, `
gopls is a Go language server.

It is typically used with an editor to provide language features. When no
command is specified, gopls will default to the 'serve' command. The language
features can also be accessed via the gopls command-line interface.

For documentation of all its features, see:

   https://github.com/golang/tools/blob/master/gopls/doc/features

Usage:
  gopls help [<subject>]

Command:
`)
	fmt.Fprint(w, "\nMain\t\n")
	for _, c := range app.mainCommands() {
		fmt.Fprintf(w, "  %s\t%s\n", c.Name(), c.ShortHelp())
	}
	fmt.Fprint(w, "\t\nFeatures\t\n")
	for _, c := range app.featureCommands() {
		fmt.Fprintf(w, "  %s\t%s\n", c.Name(), c.ShortHelp())
	}
	if app.verbose() {
		fmt.Fprint(w, "\t\nInternal Use Only\t\n")
		for _, c := range app.internalCommands() {
			fmt.Fprintf(w, "  %s\t%s\n", c.Name(), c.ShortHelp())
		}
	}
	fmt.Fprint(w, "\nflags:\n")
	printFlagDefaults(f)
}

// this is a slightly modified version of flag.PrintDefaults to give us control
func printFlagDefaults(s *flag.FlagSet) {
	var flags [][]*flag.Flag
	seen := map[flag.Value]int{}
	s.VisitAll(func(f *flag.Flag) {
		if i, ok := seen[f.Value]; !ok {
			seen[f.Value] = len(flags)
			flags = append(flags, []*flag.Flag{f})
		} else {
			flags[i] = append(flags[i], f)
		}
	})
	for _, entry := range flags {
		sort.SliceStable(entry, func(i, j int) bool {
			return len(entry[i].Name) < len(entry[j].Name)
		})
		var b strings.Builder
		for i, f := range entry {
			switch i {
			case 0:
				b.WriteString("  -")
			default:
				b.WriteString(",-")
			}
			b.WriteString(f.Name)
		}

		f := entry[0]
		name, usage := flag.UnquoteUsage(f)
		if len(name) > 0 {
			b.WriteString("=")
			b.WriteString(name)
		}
		// Boolean flags of one ASCII letter are so common we
		// treat them specially, putting their usage on the same line.
		if b.Len() <= 4 { // space, space, '-', 'x'.
			b.WriteString("\t")
		} else {
			// Four spaces before the tab triggers good alignment
			// for both 4- and 8-space tab stops.
			b.WriteString("\n    \t")
		}
		b.WriteString(strings.ReplaceAll(usage, "\n", "\n    \t"))
		if !isZeroValue(f, f.DefValue) {
			if reflect.TypeOf(f.Value).Elem().Name() == "stringValue" {
				fmt.Fprintf(&b, " (default %q)", f.DefValue)
			} else {
				fmt.Fprintf(&b, " (default %v)", f.DefValue)
			}
		}
		fmt.Fprint(s.Output(), b.String(), "\n")
	}
}

// isZeroValue is copied from the flags package
func isZeroValue(f *flag.Flag, value string) bool {
	// Build a zero value of the flag's Value type, and see if the
	// result of calling its String method equals the value passed in.
	// This works unless the Value type is itself an interface type.
	typ := reflect.TypeOf(f.Value)
	var z reflect.Value
	if typ.Kind() == reflect.Pointer {
		z = reflect.New(typ.Elem())
	} else {
		z = reflect.Zero(typ)
	}
	return value == z.Interface().(flag.Value).String()
}

// Run takes the args after top level flag processing, and invokes the correct
// sub command as specified by the first argument.
// If no arguments are passed it will invoke the server sub command, as a
// temporary measure for compatibility.
func (app *Application) Run(ctx context.Context, args ...string) error {
	// In the category of "things we can do while waiting for the Go command":
	// Pre-initialize the filecache, which takes ~50ms to hash the gopls
	// executable, and immediately runs a gc.
	filecache.Start()

	ctx = debug.WithInstance(ctx, app.OTel)
	if len(args) == 0 {
		s := flag.NewFlagSet(app.Name(), flag.ExitOnError)
		return tool.Run(ctx, s, &app.Serve, args)
	}
	command, args := args[0], args[1:]
	for _, c := range app.Commands() {
		if c.Name() == command {
			s := flag.NewFlagSet(app.Name(), flag.ExitOnError)
			return tool.Run(ctx, s, c, args)
		}
	}
	return tool.CommandLineErrorf("Unknown command %v", command)
}

// Commands returns the set of commands supported by the gopls tool on the
// command line.
// The command is specified by the first non flag argument.
func (app *Application) Commands() []tool.Application {
	var commands []tool.Application
	commands = append(commands, app.mainCommands()...)
	commands = append(commands, app.featureCommands()...)
	commands = append(commands, app.internalCommands()...)
	return commands
}

func (app *Application) mainCommands() []tool.Application {
	return []tool.Application{
		&app.Serve,
		&version{app: app},
		&bug{app: app},
		&help{app: app},
		&apiJSON{app: app},
		&licenses{app: app},
	}
}

func (app *Application) internalCommands() []tool.Application {
	return []tool.Application{
		&vulncheck{app: app},
	}
}

func (app *Application) featureCommands() []tool.Application {
	return []tool.Application{
		&callHierarchy{app: app},
		&check{app: app, Severity: "warning"},
		&codeaction{app: app},
		&codelens{app: app},
		&definition{app: app},
		&execute{app: app},
		&fix{app: app}, // (non-functional)
		&foldingRanges{app: app},
		&format{app: app},
		&headlessMCP{app: app},
		&highlight{app: app},
		&implementation{app: app},
		&imports{app: app},
		newRemote(app, ""),
		newRemote(app, "inspect"),
		&links{app: app},
		&prepareRename{app: app},
		&references{app: app},
		&rename{app: app},
		&semanticToken{app: app},
		&signature{app: app},
		&stats{app: app},
		&symbols{app: app},

		&workspaceSymbol{app: app},
	}
}

// connect creates and initializes a new in-process gopls LSP session.
func (app *Application) connect(ctx context.Context) (*client, *cache.Session, error) {
	root, err := os.Getwd()
	if err != nil {
		return nil, nil, fmt.Errorf("finding workdir: %v", err)
	}
	options := settings.DefaultOptions(app.options)
	client := newClient(app)
	var (
		svr  protocol.Server
		sess *cache.Session
	)
	if app.Remote == "" {
		// local
		sess = cache.NewSession(ctx, cache.New(nil))
		svr = server.New(sess, client, options)
		ctx = protocol.WithClient(ctx, client)
	} else {
		// remote
		netConn, err := lsprpc.ConnectToRemote(ctx, app.Remote)
		if err != nil {
			return nil, nil, err
		}
		stream := jsonrpc2.NewHeaderStream(netConn)
		jsonConn := jsonrpc2.NewConn(stream)
		svr = protocol.ServerDispatcher(jsonConn)
		ctx = protocol.WithClient(ctx, client)
		jsonConn.Go(ctx,
			protocol.Handlers(
				protocol.ClientHandler(client, jsonrpc2.MethodNotFound)))
	}
	if err := client.initialize(ctx, svr, initParams(root, options)); err != nil {
		return nil, nil, err
	}
	return client, sess, nil
}

func initParams(rootDir string, opts *settings.Options) *protocol.ParamInitialize {
	params := &protocol.ParamInitialize{}
	params.RootURI = protocol.URIFromPath(rootDir)
	params.Capabilities.Workspace.Configuration = true

	// If you add an additional option here,
	// you must update the map key of settings.DefaultOptions called in (*Application).connect.
	params.Capabilities.TextDocument.Hover = &protocol.HoverClientCapabilities{
		ContentFormat: []protocol.MarkupKind{opts.PreferredContentFormat},
	}
	params.Capabilities.TextDocument.DocumentSymbol.HierarchicalDocumentSymbolSupport = opts.HierarchicalDocumentSymbolSupport
	params.Capabilities.TextDocument.SemanticTokens = protocol.SemanticTokensClientCapabilities{}
	params.Capabilities.TextDocument.SemanticTokens.Formats = []protocol.TokenFormat{"relative"}
	params.Capabilities.TextDocument.SemanticTokens.Requests.Range = &protocol.Or_ClientSemanticTokensRequestOptions_range{Value: true}
	// params.Capabilities.TextDocument.SemanticTokens.Requests.Range.Value = true
	params.Capabilities.TextDocument.SemanticTokens.Requests.Full = &protocol.Or_ClientSemanticTokensRequestOptions_full{Value: true}
	params.Capabilities.TextDocument.SemanticTokens.TokenTypes = moreslices.ConvertStrings[string](semtok.Types)
	params.Capabilities.TextDocument.SemanticTokens.TokenModifiers = moreslices.ConvertStrings[string](semtok.Modifiers)
	params.Capabilities.TextDocument.CodeAction = protocol.CodeActionClientCapabilities{
		CodeActionLiteralSupport: protocol.ClientCodeActionLiteralOptions{
			CodeActionKind: protocol.ClientCodeActionKindOptions{
				ValueSet: []protocol.CodeActionKind{protocol.Empty}, // => all
			},
		},
	}
	params.Capabilities.Window.WorkDoneProgress = true
	params.Capabilities.Workspace.FileOperations = &protocol.FileOperationClientCapabilities{
		DidCreate: true,
	}
	params.InitializationOptions = map[string]any{
		"symbolMatcher": string(opts.SymbolMatcher),
	}
	return params
}

// initialize performs LSP's two-call client/server handshake.
func (cli *client) initialize(ctx context.Context, server protocol.Server, params *protocol.ParamInitialize) error {
	result, err := server.Initialize(ctx, params)
	if err != nil {
		return err
	}
	if err := server.Initialized(ctx, &protocol.InitializedParams{}); err != nil {
		return err
	}
	cli.server = server
	cli.initializeResult = result
	return nil
}

// client implements [protocol.Client] and defines the LSP client
// operations of the gopls command.
//
// It holds the client-side state of a single client/server
// connection; it conceptually corresponds to a single call to
// connect(2).
type client struct {
	app *Application

	server           protocol.Server
	initializeResult *protocol.InitializeResult // includes server capabilities

	progressMu sync.Mutex
	iwlToken   protocol.ProgressToken
	iwlDone    chan struct{}

	filesMu sync.Mutex // guards files map
	files   map[protocol.DocumentURI]*cmdFile
}

// cmdFile represents an open file in the gopls command LSP client.
type cmdFile struct {
	uri           protocol.DocumentURI
	mapper        *protocol.Mapper
	err           error
	diagnosticsMu sync.Mutex
	diagnostics   []protocol.Diagnostic
}

func newClient(app *Application) *client {
	return &client{
		app:     app,
		files:   make(map[protocol.DocumentURI]*cmdFile),
		iwlDone: make(chan struct{}),
	}
}

func (cli *client) TextDocumentContentRefresh(context.Context, *protocol.TextDocumentContentRefreshParams) error {
	return nil
}

func (cli *client) CodeLensRefresh(context.Context) error { return nil }

func (cli *client) FoldingRangeRefresh(context.Context) error { return nil }

func (cli *client) LogTrace(context.Context, *protocol.LogTraceParams) error { return nil }

func (cli *client) ShowMessage(ctx context.Context, p *protocol.ShowMessageParams) error {
	fmt.Fprintf(os.Stderr, "%s: %s\n", p.Type, p.Message)
	return nil
}

func (cli *client) ShowMessageRequest(ctx context.Context, p *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error) {
	return nil, nil
}

func (cli *client) LogMessage(ctx context.Context, p *protocol.LogMessageParams) error {
	// This logic causes server logging to be double-prefixed with a timestamp.
	//     2023/11/08 10:50:21 Error:2023/11/08 10:50:21 <actual message>
	// TODO(adonovan): print just p.Message, plus a newline if needed?
	switch p.Type {
	case protocol.Error:
		log.Print("Error:", p.Message)
	case protocol.Warning:
		log.Print("Warning:", p.Message)
	case protocol.Info:
		if cli.app.verbose() {
			log.Print("Info:", p.Message)
		}
	case protocol.Log:
		if cli.app.verbose() {
			log.Print("Log:", p.Message)
		}
	default:
		if cli.app.verbose() {
			log.Print(p.Message)
		}
	}
	return nil
}

func (cli *client) Event(ctx context.Context, t *any) error { return nil }

func (cli *client) RegisterCapability(ctx context.Context, p *protocol.RegistrationParams) error {
	return nil
}

func (cli *client) UnregisterCapability(ctx context.Context, p *protocol.UnregistrationParams) error {
	return nil
}

func (cli *client) WorkspaceFolders(ctx context.Context) ([]protocol.WorkspaceFolder, error) {
	return nil, nil
}

func (cli *client) Configuration(ctx context.Context, p *protocol.ParamConfiguration) ([]any, error) {
	results := make([]any, len(p.Items))
	for i, item := range p.Items {
		if item.Section != "gopls" {
			continue
		}
		m := map[string]any{
			"analyses": map[string]any{
				"fillreturns":    true,
				"nonewvars":      true,
				"noresultvalues": true,
				"undeclaredname": true,
			},
		}
		if cli.app.VeryVerbose {
			m["verboseOutput"] = true
		}
		results[i] = m
	}
	return results, nil
}

func (cli *client) ApplyEdit(ctx context.Context, p *protocol.ApplyWorkspaceEditParams) (*protocol.ApplyWorkspaceEditResult, error) {
	if err := cli.applyWorkspaceEdit(&p.Edit); err != nil {
		return &protocol.ApplyWorkspaceEditResult{FailureReason: err.Error()}, nil
	}
	return &protocol.ApplyWorkspaceEditResult{Applied: true}, nil
}

// applyWorkspaceEdit applies a complete WorkspaceEdit to the client's
// files, honoring the preferred edit mode specified by cli.app.editMode.
// (Used by rename and by ApplyEdit downcalls.)
//
// See also:
//   - changedFiles in ../test/marker/marker_test.go for the golden-file capturing variant
//   - applyWorkspaceEdit in ../test/integration/fake/editor.go for the Editor variant
func (cli *client) applyWorkspaceEdit(wsedit *protocol.WorkspaceEdit) error {

	create := func(uri protocol.DocumentURI, content []byte) error {
		edits := []diff.Edit{{Start: 0, End: 0, New: string(content)}}
		return updateFile(uri.Path(), nil, content, edits, cli.app.editFlags)
	}

	delete := func(uri protocol.DocumentURI, content []byte) error {
		edits := []diff.Edit{{Start: 0, End: len(content), New: ""}}
		return updateFile(uri.Path(), content, nil, edits, cli.app.editFlags)
	}

	for _, c := range wsedit.DocumentChanges {
		switch {
		case c.TextDocumentEdit != nil:
			f := cli.getFile(c.TextDocumentEdit.TextDocument.URI)
			if f.err != nil {
				return f.err
			}
			// TODO(adonovan): sanity-check c.TextDocumentEdit.TextDocument.Version
			edits := protocol.AsTextEdits(c.TextDocumentEdit.Edits)
			if err := applyTextEdits(f.mapper, edits, cli.app.editFlags); err != nil {
				return err
			}

		case c.CreateFile != nil:
			if err := create(c.CreateFile.URI, []byte{}); err != nil {
				return err
			}

		case c.RenameFile != nil:
			// Analyze as creation + deletion. (NB: loses file mode.)
			f := cli.getFile(c.RenameFile.OldURI)
			if f.err != nil {
				return f.err
			}
			if err := create(c.RenameFile.NewURI, f.mapper.Content); err != nil {
				return err
			}
			if err := delete(f.mapper.URI, f.mapper.Content); err != nil {
				return err
			}

		case c.DeleteFile != nil:
			f := cli.getFile(c.DeleteFile.URI)
			if f.err != nil {
				return f.err
			}
			if err := delete(f.mapper.URI, f.mapper.Content); err != nil {
				return err
			}

		default:
			return fmt.Errorf("unknown DocumentChange: %#v", c)
		}
	}
	return nil
}

// applyTextEdits applies a list of edits to the mapper file content,
// using the preferred edit mode. It is a no-op if there are no edits.
func applyTextEdits(mapper *protocol.Mapper, edits []protocol.TextEdit, flags *EditFlags) error {
	if len(edits) == 0 {
		return nil
	}
	newContent, diffEdits, err := protocol.ApplyEdits(mapper, edits)
	if err != nil {
		return err
	}
	return updateFile(mapper.URI.Path(), mapper.Content, newContent, diffEdits, flags)
}

// updateFile performs a content update operation on the specified file.
// If the old content is nil, the operation creates the file.
// If the new content is nil, the operation deletes the file.
// The flags control whether the operation is written, or merely listed, diffed, or printed.
func updateFile(filename string, old, new []byte, edits []diff.Edit, flags *EditFlags) error {
	if flags.List {
		fmt.Println(filename)
	}

	if flags.Write {
		if flags.Preserve && old != nil { // edit or delete
			if err := os.WriteFile(filename+".orig", old, 0666); err != nil {
				return err
			}
		}

		if new != nil {
			// create or edit
			if err := os.WriteFile(filename, new, 0666); err != nil {
				return err
			}
		} else {
			// delete
			if err := os.Remove(filename); err != nil {
				return err
			}
		}
	}

	if flags.Diff {
		// For diffing, creations and deletions are equivalent
		// updating an empty file and making an existing file empty.
		unified, err := diff.ToUnified(filename+".orig", filename, string(old), edits, diff.DefaultContextLines)
		if err != nil {
			return err
		}
		fmt.Print(unified)
	}

	// No flags: just print edited file content.
	//
	// This makes no sense for multiple files.
	// (We should probably change the default to -diff.)
	if !(flags.List || flags.Write || flags.Diff) {
		os.Stdout.Write(new)
	}

	return nil
}

func (cli *client) PublishDiagnostics(ctx context.Context, p *protocol.PublishDiagnosticsParams) error {
	// Don't worry about diagnostics without versions.
	//
	// (Note: the representation of PublishDiagnosticsParams
	// cannot distinguish a missing Version from v0, but the
	// server never sends back an explicit zero.)
	if p.Version == 0 {
		return nil
	}

	file := cli.getFile(p.URI)

	file.diagnosticsMu.Lock()
	defer file.diagnosticsMu.Unlock()

	file.diagnostics = append(file.diagnostics, p.Diagnostics...)

	// Perform a crude in-place deduplication.
	// TODO(golang/go#60122): replace the gopls.diagnose_files
	// command with support for textDocument/diagnostic,
	// so that we don't need to do this de-duplication.
	type key [6]any
	seen := make(map[key]bool)
	out := file.diagnostics[:0]
	for _, d := range file.diagnostics {
		var codeHref string
		if desc := d.CodeDescription; desc != nil {
			codeHref = desc.Href
		}
		k := key{d.Range, d.Severity, d.Code, codeHref, d.Source, d.Message}
		if !seen[k] {
			seen[k] = true
			out = append(out, d)
		}
	}
	file.diagnostics = out

	return nil
}

func (cli *client) Progress(_ context.Context, params *protocol.ProgressParams) error {
	if _, ok := params.Token.(string); !ok {
		return fmt.Errorf("unexpected progress token: %[1]T %[1]v", params.Token)
	}

	switch v := params.Value.(type) {
	case *protocol.WorkDoneProgressBegin:
		if v.Title == server.DiagnosticWorkTitle(server.FromInitialWorkspaceLoad) {
			cli.progressMu.Lock()
			cli.iwlToken = params.Token
			cli.progressMu.Unlock()
		}

	case *protocol.WorkDoneProgressReport:
		if cli.app.Verbose {
			fmt.Fprintln(os.Stderr, v.Message)
		}

	case *protocol.WorkDoneProgressEnd:
		cli.progressMu.Lock()
		iwlToken := cli.iwlToken
		cli.progressMu.Unlock()

		if params.Token == iwlToken {
			close(cli.iwlDone)
		}
	}
	return nil
}

func (cli *client) ShowDocument(ctx context.Context, params *protocol.ShowDocumentParams) (*protocol.ShowDocumentResult, error) {
	var success bool
	if params.External {
		// Open URI in external browser.
		success = browser.Open(params.URI)
	} else {
		// Open file in editor, optionally taking focus and selecting a range.
		// (client has no editor. Should it fork+exec $EDITOR?)
		log.Printf("Server requested that client editor open %q (takeFocus=%t, selection=%+v)",
			params.URI, params.TakeFocus, params.Selection)
		success = true
	}
	return &protocol.ShowDocumentResult{Success: success}, nil
}

func (cli *client) WorkDoneProgressCreate(context.Context, *protocol.WorkDoneProgressCreateParams) error {
	return nil
}

func (cli *client) DiagnosticRefresh(context.Context) error {
	return nil
}

func (cli *client) InlayHintRefresh(context.Context) error {
	return nil
}

func (cli *client) SemanticTokensRefresh(context.Context) error {
	return nil
}

func (cli *client) InlineValueRefresh(context.Context) error {
	return nil
}

// getFile returns the specified file, adding it to the client state if needed.
func (cli *client) getFile(uri protocol.DocumentURI) *cmdFile {
	cli.filesMu.Lock()
	defer cli.filesMu.Unlock()

	file, found := cli.files[uri]
	if !found || file.err != nil {
		file = &cmdFile{
			uri: uri,
		}
		cli.files[uri] = file
	}
	if file.mapper == nil {
		content, err := os.ReadFile(uri.Path())
		if err != nil {
			file.err = fmt.Errorf("getFile: %v: %v", uri, err)
			return file
		}
		file.mapper = protocol.NewMapper(uri, content)
	}
	return file
}

// openFile returns the specified file, adding it to the client state
// if needed, and notifying the server that it was opened.
func (cli *client) openFile(ctx context.Context, uri protocol.DocumentURI) (*cmdFile, error) {
	file := cli.getFile(uri)
	if file.err != nil {
		return nil, file.err
	}

	// Choose language ID from file extension.
	var langID protocol.LanguageKind // "" eventually maps to file.UnknownKind
	switch filepath.Ext(uri.Path()) {
	case ".go":
		langID = "go"
	case ".mod":
		langID = "go.mod"
	case ".sum":
		langID = "go.sum"
	case ".work":
		langID = "go.work"
	case ".s":
		langID = "go.s"
	}

	p := &protocol.DidOpenTextDocumentParams{
		TextDocument: protocol.TextDocumentItem{
			URI:        uri,
			LanguageID: langID,
			Version:    1,
			Text:       string(file.mapper.Content),
		},
	}
	if err := cli.server.DidOpen(ctx, p); err != nil {
		// TODO(adonovan): is this assignment concurrency safe?
		file.err = fmt.Errorf("%v: %v", uri, err)
		return nil, file.err
	}
	return file, nil
}

func diagnoseFiles(ctx context.Context, server protocol.Server, files []protocol.DocumentURI) error {
	cmd := command.NewDiagnoseFilesCommand("Diagnose files", command.DiagnoseFilesArgs{
		Files: files,
	})
	_, err := executeCommand(ctx, server, cmd)
	return err
}

func (cli *client) terminate(ctx context.Context) {
	if err := cli.server.Shutdown(ctx); err != nil {
		log.Printf("server shutdown failed: %v", err)
	}

	// Don't call Exit as it terminates the server process,
	// which is the same as this client process.
	// c.server.Exit(ctx)
}

// Implement io.Closer.
func (cli *client) Close() error {
	return nil
}

// -- conversions to span (UTF-8) domain --

// locationSpan converts a protocol (UTF-16) Location to a (UTF-8) span.
// Precondition: the URIs of Location and Mapper match.
func (f *cmdFile) locationSpan(loc protocol.Location) (span, error) {
	// TODO(adonovan): check that l.URI matches m.URI.
	return f.rangeSpan(loc.Range)
}

// rangeSpan converts a protocol (UTF-16) range to a (UTF-8) span.
// The resulting span has valid Positions and Offsets.
func (f *cmdFile) rangeSpan(r protocol.Range) (span, error) {
	start, end, err := f.mapper.RangeOffsets(r)
	if err != nil {
		return span{}, err
	}
	return f.offsetSpan(start, end)
}

// offsetSpan converts a byte-offset interval to a (UTF-8) span.
// The resulting span contains line, column, and offset information.
func (f *cmdFile) offsetSpan(start, end int) (span, error) {
	if start > end {
		return span{}, fmt.Errorf("start offset (%d) > end (%d)", start, end)
	}
	startPoint, err := offsetPoint(f.mapper, start)
	if err != nil {
		return span{}, fmt.Errorf("start: %v", err)
	}
	endPoint, err := offsetPoint(f.mapper, end)
	if err != nil {
		return span{}, fmt.Errorf("end: %v", err)
	}
	return newSpan(f.mapper.URI, startPoint, endPoint), nil
}

// offsetPoint converts a byte offset to a span (UTF-8) point.
// The resulting point contains line, column, and offset information.
func offsetPoint(m *protocol.Mapper, offset int) (point, error) {
	if !(0 <= offset && offset <= len(m.Content)) {
		return point{}, fmt.Errorf("invalid offset %d (want 0-%d)", offset, len(m.Content))
	}
	line, col8 := m.OffsetLineCol8(offset)
	return newPoint(line, col8, offset), nil
}

// -- conversions from span (UTF-8) domain --

// spanLocation converts a (UTF-8) span to a protocol (UTF-16) range.
// Precondition: the URIs of spanLocation and Mapper match.
func (f *cmdFile) spanLocation(s span) (protocol.Location, error) {
	rng, err := f.spanRange(s)
	if err != nil {
		return protocol.Location{}, err
	}
	return f.mapper.URI.Location(rng), nil
}

// spanRange converts a (UTF-8) span to a protocol (UTF-16) range.
// Precondition: the URIs of span and Mapper match.
func (f *cmdFile) spanRange(s span) (protocol.Range, error) {
	// Assert that we aren't using the wrong mapper.
	// We check only the base name, and case insensitively,
	// because we can't assume clean paths, no symbolic links,
	// case-sensitive directories. The authoritative answer
	// requires querying the file system, and we don't want
	// to do that.
	if !strings.EqualFold(f.mapper.URI.Base(), s.URI().Base()) {
		return protocol.Range{}, bugpkg.Errorf("mapper is for file %q instead of %q", f.mapper.URI, s.URI())
	}
	start, err := pointPosition(f.mapper, s.Start())
	if err != nil {
		return protocol.Range{}, fmt.Errorf("start: %w", err)
	}
	end, err := pointPosition(f.mapper, s.End())
	if err != nil {
		return protocol.Range{}, fmt.Errorf("end: %w", err)
	}
	return protocol.Range{Start: start, End: end}, nil
}

// pointPosition converts a valid span (UTF-8) point to a protocol (UTF-16) position.
func pointPosition(m *protocol.Mapper, p point) (protocol.Position, error) {
	if p.HasPosition() {
		return m.LineCol8Position(p.Line(), p.Column())
	}
	if p.HasOffset() {
		return m.OffsetPosition(p.Offset())
	}
	return protocol.Position{}, fmt.Errorf("point has neither offset nor line/column")
}

// TODO(adonovan): delete in 2025.
type fix struct{ app *Application }

func (*fix) Name() string       { return "fix" }
func (cmd *fix) Parent() string { return cmd.app.Name() }
func (*fix) Usage() string      { return "" }
func (*fix) ShortHelp() string  { return "apply suggested fixes (obsolete)" }
func (*fix) DetailedHelp(flags *flag.FlagSet) {
	fmt.Fprintf(flags.Output(), `No longer supported; use "gopls codeaction" instead.`)
}
func (*fix) Run(ctx context.Context, args ...string) error {
	return tool.CommandLineErrorf(`no longer supported; use "gopls codeaction" instead`)
}


================================================
FILE: gopls/internal/cmd/codeaction.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"regexp"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// codeaction implements the codeaction verb for gopls.
type codeaction struct {
	EditFlags
	Kind  string `flag:"kind" help:"comma-separated list of code action kinds to filter"`
	Title string `flag:"title" help:"regular expression to match title"`
	Exec  bool   `flag:"exec" help:"execute the first matching code action"`

	app *Application
}

func (cmd *codeaction) Name() string      { return "codeaction" }
func (cmd *codeaction) Parent() string    { return cmd.app.Name() }
func (cmd *codeaction) Usage() string     { return "[codeaction-flags] filename[:line[:col]]" }
func (cmd *codeaction) ShortHelp() string { return "list or execute code actions" }
func (cmd *codeaction) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprintf(f.Output(), `

The codeaction command lists or executes code actions for the
specified file or range of a file. Each code action contains
either an edit to be directly applied to the file, or a command
to be executed by the server, which may have an effect such as:
- requesting that the client apply an edit;
- changing the state of the server; or
- requesting that the client open a document.

The -kind and and -title flags filter the list of actions.

The -kind flag specifies a comma-separated list of LSP CodeAction kinds.
Only actions of these kinds will be requested from the server.
Valid kinds include:

	gopls.doc.features
	quickfix
	refactor
	refactor.extract
	refactor.extract.constant
	refactor.extract.function
	refactor.extract.method
	refactor.extract.toNewFile
	refactor.extract.variable
	refactor.inline
	refactor.inline.call
	refactor.rewrite
	refactor.rewrite.changeQuote
	refactor.rewrite.fillStruct
	refactor.rewrite.fillSwitch
	refactor.rewrite.invertIf
	refactor.rewrite.joinLines
	refactor.rewrite.removeUnusedParam
	refactor.rewrite.splitLines
	source
	source.assembly
	source.doc
	source.fixAll
	source.freesymbols
	source.organizeImports
	source.test

Kinds are hierarchical, so "refactor" includes "refactor.inline".
(Note: actions of kind "source.test" are not returned unless explicitly
requested.)

The -title flag specifies a regular expression that must match the
action's title. (Ideally kinds would be specific enough that this
isn't necessary; we really need to subdivide refactor.rewrite; see
gopls/internal/settings/codeactionkind.go.)

The -exec flag causes the first matching code action to be executed.
Without the flag, the matching actions are merely listed.

It is not currently possible to execute more than one action,
as that requires a way to detect and resolve conflicts.
TODO(adonovan): support it when golang/go#67049 is resolved.

If executing an action causes the server to send a patch to the
client, the usual -write, -preserve, -diff, and -list flags govern how
the client deals with the patch.

Example: execute the first "quick fix" in the specified file and show the diff:

	$ gopls codeaction -kind=quickfix -exec -diff ./gopls/main.go

codeaction-flags:
`)
	printFlagDefaults(f)
}

func (cmd *codeaction) Run(ctx context.Context, args ...string) error {
	if len(args) < 1 {
		return tool.CommandLineErrorf("codeaction expects at least 1 argument")
	}
	cmd.app.editFlags = &cmd.EditFlags
	cli, _, err := cmd.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	uri := from.URI()
	file, err := cli.openFile(ctx, uri)
	if err != nil {
		return err
	}
	rng, err := file.spanRange(from)
	if err != nil {
		return err
	}

	titleRE, err := regexp.Compile(cmd.Title)
	if err != nil {
		return err
	}

	// Get diagnostics, as they may encode various lazy code actions.
	if err := diagnoseFiles(ctx, cli.server, []protocol.DocumentURI{uri}); err != nil {
		return err
	}
	file.diagnosticsMu.Lock()
	diagnostics := slices.Clone(file.diagnostics)
	file.diagnosticsMu.Unlock()

	// Request code actions of the desired kinds.
	var kinds []protocol.CodeActionKind
	if cmd.Kind != "" {
		for kind := range strings.SplitSeq(cmd.Kind, ",") {
			kinds = append(kinds, protocol.CodeActionKind(kind))
		}
	} else {
		kinds = append(kinds, protocol.Empty) // => all
	}
	actions, err := cli.server.CodeAction(ctx, &protocol.CodeActionParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: uri},
		Range:        rng,
		Context: protocol.CodeActionContext{
			Only:        kinds,
			Diagnostics: diagnostics,
		},
	})
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}

	// Gather edits from matching code actions.
	var edits []protocol.TextEdit
	for _, act := range actions {
		if act.Disabled != nil {
			continue
		}
		if !titleRE.MatchString(act.Title) {
			continue
		}

		// If the provided span has a position (not just offsets),
		// and the action has diagnostics, the action must have a
		// diagnostic with the same range as it.
		if from.HasPosition() && len(act.Diagnostics) > 0 &&
			!slices.ContainsFunc(act.Diagnostics, func(diag protocol.Diagnostic) bool {
				return diag.Range.Start == rng.Start
			}) {
			continue
		}

		if cmd.Exec {
			// -exec: run the first matching code action.
			if act.Command != nil {
				// This may cause the server to make
				// an ApplyEdit downcall to the client.
				if _, err := executeCommand(ctx, cli.server, act.Command); err != nil {
					return err
				}
				// The specification says that commands should
				// be executed _after_ edits are applied, not
				// instead of them, but we don't want to
				// duplicate edits.
			} else {
				// Partially apply CodeAction.Edit, a WorkspaceEdit.
				// (See also cli.applyWorkspaceEdit(a.Edit)).
				for _, c := range act.Edit.DocumentChanges {
					tde := c.TextDocumentEdit
					if tde != nil && tde.TextDocument.URI == uri {
						// TODO(adonovan): this logic will butcher an edit that spans files.
						// It will also ignore create/delete/rename operations.
						// Fix or document. Need a three-way merge.
						edits = append(edits, protocol.AsTextEdits(tde.Edits)...)
					}
				}
				return applyTextEdits(file.mapper, edits, cmd.app.editFlags)
			}
			return nil
		} else {
			// No -exec: list matching code actions.
			action := "edit"
			if act.Command != nil {
				action = "command"
			}
			fmt.Printf("%s\t%q [%s]\n",
				action,
				act.Title,
				act.Kind)
		}
	}

	if cmd.Exec {
		return fmt.Errorf("no matching code action at %s", from)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/codelens.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/tool"
)

// codelens implements the codelens verb for gopls.
type codelens struct {
	EditFlags
	app *Application

	Exec bool `flag:"exec" help:"execute the first matching code lens"`
}

func (r *codelens) Name() string      { return "codelens" }
func (r *codelens) Parent() string    { return r.app.Name() }
func (r *codelens) Usage() string     { return "[codelens-flags] file[:line[:col]] [title]" }
func (r *codelens) ShortHelp() string { return "List or execute code lenses for a file" }
func (r *codelens) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
The codelens command lists or executes code lenses for the specified
file, or line within a file. A code lens is a command associated with
a position in the code.

With an optional title argument, only code lenses matching that
title are considered.

By default, the codelens command lists the available lenses for the
specified file or line within a file, including the title and
title of the command. With the -exec flag, the first matching command
is executed, and its output is printed to stdout.

Example:

	$ gopls codelens a_test.go                     # list code lenses in a file
	$ gopls codelens a_test.go:10                  # list code lenses on line 10
	$ gopls codelens a_test.go "run test"          # list gopls.run_tests commands
	$ gopls codelens -exec a_test.go:10 "run test" # run a specific test

codelens-flags:
`)
	printFlagDefaults(f)
}

func (r *codelens) Run(ctx context.Context, args ...string) error {
	var filename, title string
	switch len(args) {
	case 0:
		return tool.CommandLineErrorf("codelens requires a file name")
	case 2:
		title = args[1]
		fallthrough
	case 1:
		filename = args[0]
	default:
		return tool.CommandLineErrorf("codelens expects at most two arguments")
	}

	r.app.editFlags = &r.EditFlags // in case a codelens perform an edit

	// Override the default setting for codelenses["test"], which is
	// off by default because VS Code has a superior client-side
	// implementation. But this client is not VS Code.
	// See golang.LensFuncs().
	origOptions := r.app.options
	r.app.options = func(opts *settings.Options) {
		if origOptions != nil {
			origOptions(opts)
		}
		if opts.Codelenses == nil {
			opts.Codelenses = make(map[settings.CodeLensSource]bool)
		}
		opts.Codelenses[settings.CodeLensTest] = true
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	filespan := parseSpan(filename)
	file, err := cli.openFile(ctx, filespan.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(filespan)
	if err != nil {
		return err
	}

	p := protocol.CodeLensParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
	}
	lenses, err := cli.server.CodeLens(ctx, &p)
	if err != nil {
		return err
	}

	for _, lens := range lenses {
		sp, err := file.rangeSpan(lens.Range)
		if err != nil {
			return nil
		}

		if title != "" && lens.Command.Title != title {
			continue // title was specified but does not match
		}
		if filespan.HasPosition() && !protocol.Intersect(loc.Range, lens.Range) {
			continue // position was specified but does not match
		}

		// -exec: run the first matching code lens.
		if r.Exec {
			_, err := executeCommand(ctx, cli.server, lens.Command)
			return err
		}

		// No -exec: list matching code lenses.
		fmt.Printf("%v: %q [%s]\n", sp, lens.Command.Title, lens.Command.Command)
	}

	if r.Exec {
		return fmt.Errorf("no code lens at %s with title %q", filespan, title)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/counters.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import "golang.org/x/telemetry/counter"

// Proposed counters for evaluating usage of the Go MCP Server. These counters
// increment when the user starts up the server in attached or headless mode.
var (
	countHeadlessMCPStdIO = counter.New("gopls/mcp-headless:stdio")
	countHeadlessMCPSSE   = counter.New("gopls/mcp-headless:sse")
	countAttachedMCP      = counter.New("gopls/mcp")
)


================================================
FILE: gopls/internal/cmd/definition.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/tool"
)

// A Definition is the result of a 'definition' query.
type Definition struct {
	Span        span   `json:"span"`        // span of the definition
	Description string `json:"description"` // description of the denoted object
}

// These constant is printed in the help, and then used in a test to verify the
// help is still valid.
// They refer to "Set" in "flag.FlagSet" from the DetailedHelp method below.
const (
	exampleLine   = 44
	exampleColumn = 47
	exampleOffset = 1270
)

// definition implements the definition verb for gopls.
type definition struct {
	app *Application

	JSON              bool `flag:"json" help:"emit output in JSON format"`
	MarkdownSupported bool `flag:"markdown" help:"support markdown in responses"`
}

func (d *definition) Name() string      { return "definition" }
func (d *definition) Parent() string    { return d.app.Name() }
func (d *definition) Usage() string     { return "[definition-flags] <position>" }
func (d *definition) ShortHelp() string { return "show declaration of selected identifier" }
func (d *definition) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprintf(f.Output(), `
Example: show the definition of the identifier at syntax at offset %[1]v in this file (flag.FlagSet):

	$ gopls definition internal/cmd/definition.go:%[1]v:%[2]v
	$ gopls definition internal/cmd/definition.go:#%[3]v

definition-flags:
`, exampleLine, exampleColumn, exampleOffset)
	printFlagDefaults(f)
}

// Run performs the definition query as specified by args and prints the
// results to stdout.
func (d *definition) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("definition expects 1 argument")
	}
	// Plaintext makes more sense for the command line.
	opts := d.app.options
	d.app.options = func(o *settings.Options) {
		if opts != nil {
			opts(o)
		}
		o.PreferredContentFormat = protocol.PlainText
		if d.MarkdownSupported {
			o.PreferredContentFormat = protocol.Markdown
		}
	}
	cli, _, err := d.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)
	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}
	p := protocol.DefinitionParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	locs, err := cli.server.Definition(ctx, &p)
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}

	if len(locs) == 0 {
		return fmt.Errorf("%v: no definition location (not an identifier?)", from)
	}
	file, err = cli.openFile(ctx, locs[0].URI)
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}
	definition, err := file.locationSpan(locs[0])
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}

	q := protocol.HoverParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	hover, err := cli.server.Hover(ctx, &q)
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}
	var description string
	if hover != nil {
		description = strings.TrimSpace(hover.Contents.Value)
	}

	result := &Definition{
		Span:        definition,
		Description: description,
	}
	if d.JSON {
		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "\t")
		return enc.Encode(result)
	}
	fmt.Printf("%v", result.Span)
	if len(result.Description) > 0 {
		fmt.Printf(": defined here as %s", result.Description)
	}
	fmt.Printf("\n")
	return nil
}


================================================
FILE: gopls/internal/cmd/execute.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"log"
	"slices"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/internal/tool"
)

// execute implements the LSP ExecuteCommand verb for gopls.
type execute struct {
	EditFlags
	app *Application
}

func (e *execute) Name() string      { return "execute" }
func (e *execute) Parent() string    { return e.app.Name() }
func (e *execute) Usage() string     { return "[flags] command argument..." }
func (e *execute) ShortHelp() string { return "Execute a gopls custom LSP command" }
func (e *execute) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
The execute command sends an LSP ExecuteCommand request to gopls,
with a set of optional JSON argument values.
Some commands return a result, also JSON.

Gopls' command set is defined by the command.Interface type; see
https://pkg.go.dev/golang.org/x/tools/gopls/internal/protocol/command#Interface.
It is not a stable interface: commands may change or disappear without notice.

Examples:

	$ gopls execute gopls.add_import '{"ImportPath": "fmt", "URI": "file:///hello.go"}'
	$ gopls execute gopls.run_tests '{"URI": "file:///a_test.go", "Tests": ["Test"]}'
	$ gopls execute gopls.list_known_packages '{"URI": "file:///hello.go"}'

execute-flags:
`)
	printFlagDefaults(f)
}

func (e *execute) Run(ctx context.Context, args ...string) error {
	if len(args) == 0 {
		return tool.CommandLineErrorf("execute requires a command name")
	}
	cmd := args[0]
	if !slices.Contains(command.Commands, command.Command(cmd)) {
		return tool.CommandLineErrorf("unrecognized command: %s", cmd)
	}

	// A command may have multiple arguments, though the only one
	// that currently does so is the "legacy" gopls.test,
	// so we don't show an example of it.
	var jsonArgs []json.RawMessage
	for i, arg := range args[1:] {
		var dummy any
		if err := json.Unmarshal([]byte(arg), &dummy); err != nil {
			return fmt.Errorf("argument %d is not valid JSON: %v", i+1, err)
		}
		jsonArgs = append(jsonArgs, json.RawMessage(arg))
	}

	e.app.editFlags = &e.EditFlags // in case command performs an edit

	cli, _, err := e.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	res, err := executeCommand(ctx, cli.server, &protocol.Command{
		Command:   cmd,
		Arguments: jsonArgs,
	})
	if err != nil {
		return err
	}
	if res != nil {
		data, err := json.MarshalIndent(res, "", "\t")
		if err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s\n", data)
	}
	return nil
}

// executeCommand executes a protocol.Command, displaying progress
// messages and awaiting completion of asynchronous commands.
func executeCommand(ctx context.Context, server protocol.Server, cmd *protocol.Command) (any, error) {
	return server.ExecuteCommand(ctx, &protocol.ExecuteCommandParams{
		Command:   cmd.Command,
		Arguments: cmd.Arguments,
	})
}


================================================
FILE: gopls/internal/cmd/folding_range.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// foldingRanges implements the folding_ranges verb for gopls
type foldingRanges struct {
	app *Application
}

func (r *foldingRanges) Name() string      { return "folding_ranges" }
func (r *foldingRanges) Parent() string    { return r.app.Name() }
func (r *foldingRanges) Usage() string     { return "<file>" }
func (r *foldingRanges) ShortHelp() string { return "display selected file's folding ranges" }
func (r *foldingRanges) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ gopls folding_ranges helper/helper.go
`)
	printFlagDefaults(f)
}

func (r *foldingRanges) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("folding_ranges expects 1 argument (file)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	if _, err := cli.openFile(ctx, from.URI()); err != nil {
		return err
	}

	p := protocol.FoldingRangeParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: from.URI(),
		},
	}

	ranges, err := cli.server.FoldingRange(ctx, &p)
	if err != nil {
		return err
	}

	for _, r := range ranges {
		// We assume our server always supplies these fields.
		fmt.Printf("%v:%v-%v:%v\n",
			*r.StartLine+1,
			*r.StartCharacter+1,
			*r.EndLine+1,
			*r.EndCharacter+1,
		)
	}

	return nil
}


================================================
FILE: gopls/internal/cmd/format.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
)

// format implements the format verb for gopls.
type format struct {
	EditFlags
	app *Application
}

func (c *format) Name() string      { return "format" }
func (c *format) Parent() string    { return c.app.Name() }
func (c *format) Usage() string     { return "[format-flags] <filerange>" }
func (c *format) ShortHelp() string { return "format the code according to the go standard" }
func (c *format) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
The arguments supplied may be simple file names, or ranges within files.

Example: reformat this file:

	$ gopls format -w internal/cmd/check.go

format-flags:
`)
	printFlagDefaults(f)
}

// Run performs the check on the files specified by args and prints the
// results to stdout.
func (c *format) Run(ctx context.Context, args ...string) error {
	if len(args) == 0 {
		return nil
	}
	c.app.editFlags = &c.EditFlags
	cli, _, err := c.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)
	for _, arg := range args {
		spn := parseSpan(arg)
		file, err := cli.openFile(ctx, spn.URI())
		if err != nil {
			return err
		}
		loc, err := file.spanLocation(spn)
		if err != nil {
			return err
		}
		if loc.Range.Start != loc.Range.End {
			return fmt.Errorf("only full file formatting supported")
		}
		p := protocol.DocumentFormattingParams{
			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
		}
		edits, err := cli.server.Formatting(ctx, &p)
		if err != nil {
			return fmt.Errorf("%v: %v", spn, err)
		}
		if err := applyTextEdits(file.mapper, edits, c.app.editFlags); err != nil {
			return err
		}
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/help_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd_test

// This file defines tests to ensure the cmd/usage/*.hlp files match
// the output of the tool. The .hlp files are not actually needed by
// the executable (they are not //go:embed-ded, say), but they make it
// easier to review changes to the gopls command's help logic since
// any effects are manifest as changes to these files.

//go:generate go test -run Help -update-help-files

import (
	"bytes"
	"context"
	"flag"
	"os"
	"path/filepath"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/cmd"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/tool"
)

var updateHelpFiles = flag.Bool("update-help-files", false, "Write out the help files instead of checking them")

const appName = "gopls"

func TestHelpFiles(t *testing.T) {
	testenv.NeedsGoBuild(t) // This is a lie. We actually need the source code.
	app := cmd.New()
	ctx := context.Background()
	for _, page := range append(app.Commands(), app) {
		t.Run(page.Name(), func(t *testing.T) {
			var buf bytes.Buffer
			s := flag.NewFlagSet(page.Name(), flag.ContinueOnError)
			s.SetOutput(&buf)
			tool.Run(ctx, s, page, []string{"-h"}) // ignore error
			name := page.Name()
			if name == appName {
				name = "usage"
			}
			helpFile := filepath.Join("usage", name+".hlp")
			got := buf.Bytes()
			if *updateHelpFiles {
				if err := os.WriteFile(helpFile, got, 0666); err != nil {
					t.Errorf("Failed writing %v: %v", helpFile, err)
				}
				return
			}
			want, err := os.ReadFile(helpFile)
			if err != nil {
				t.Fatalf("Missing help file %q", helpFile)
			}
			if diff := cmp.Diff(string(want), string(got)); diff != "" {
				t.Errorf("Help file %q did not match, run with -update-help-files to fix (-want +got)\n%s", helpFile, diff)
			}
		})
	}
}

func TestVerboseHelp(t *testing.T) {
	testenv.NeedsGoBuild(t) // This is a lie. We actually need the source code.
	app := cmd.New()
	ctx := context.Background()
	var buf bytes.Buffer
	s := flag.NewFlagSet(appName, flag.ContinueOnError)
	s.SetOutput(&buf)
	tool.Run(ctx, s, app, []string{"-v", "-h"}) // ignore error
	got := buf.Bytes()

	helpFile := filepath.Join("usage", "usage-v.hlp")
	if *updateHelpFiles {
		if err := os.WriteFile(helpFile, got, 0666); err != nil {
			t.Errorf("Failed writing %v: %v", helpFile, err)
		}
		return
	}
	want, err := os.ReadFile(helpFile)
	if err != nil {
		t.Fatalf("Missing help file %q", helpFile)
	}
	if diff := cmp.Diff(string(want), string(got)); diff != "" {
		t.Errorf("Help file %q did not match, run with -update-help-files to fix (-want +got)\n%s", helpFile, diff)
	}
}


================================================
FILE: gopls/internal/cmd/highlight.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// highlight implements the highlight verb for gopls.
type highlight struct {
	app *Application
}

func (r *highlight) Name() string      { return "highlight" }
func (r *highlight) Parent() string    { return r.app.Name() }
func (r *highlight) Usage() string     { return "<position>" }
func (r *highlight) ShortHelp() string { return "display selected identifier's highlights" }
func (r *highlight) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls highlight helper/helper.go:8:6
	$ gopls highlight helper/helper.go:#53
`)
	printFlagDefaults(f)
}

func (r *highlight) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("highlight expects 1 argument (position)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}

	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}

	p := protocol.DocumentHighlightParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	highlights, err := cli.server.DocumentHighlight(ctx, &p)
	if err != nil {
		return err
	}

	var results []span
	for _, h := range highlights {
		s, err := file.rangeSpan(h.Range)
		if err != nil {
			return err
		}
		results = append(results, s)
	}
	// Sort results to make tests deterministic since DocumentHighlight uses a map.
	sortSpans(results)

	for _, s := range results {
		fmt.Println(s)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/implementation.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"sort"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// implementation implements the implementation verb for gopls
type implementation struct {
	app *Application
}

func (i *implementation) Name() string      { return "implementation" }
func (i *implementation) Parent() string    { return i.app.Name() }
func (i *implementation) Usage() string     { return "<position>" }
func (i *implementation) ShortHelp() string { return "display selected identifier's implementation" }
func (i *implementation) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls implementation helper/helper.go:8:6
	$ gopls implementation helper/helper.go:#53
`)
	printFlagDefaults(f)
}

func (i *implementation) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("implementation expects 1 argument (position)")
	}

	cli, _, err := i.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}

	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}

	p := protocol.ImplementationParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	implementations, err := cli.server.Implementation(ctx, &p)
	if err != nil {
		return err
	}

	var spans []string
	for _, impl := range implementations {
		f, err := cli.openFile(ctx, impl.URI)
		if err != nil {
			return err
		}
		span, err := f.locationSpan(impl)
		if err != nil {
			return err
		}
		spans = append(spans, fmt.Sprint(span))
	}
	sort.Strings(spans)

	for _, s := range spans {
		fmt.Println(s)
	}

	return nil
}


================================================
FILE: gopls/internal/cmd/imports.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// imports implements the import verb for gopls.
type imports struct {
	EditFlags
	app *Application
}

func (t *imports) Name() string      { return "imports" }
func (t *imports) Parent() string    { return t.app.Name() }
func (t *imports) Usage() string     { return "[imports-flags] <filename>" }
func (t *imports) ShortHelp() string { return "updates import statements" }
func (t *imports) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprintf(f.Output(), `
Example: update imports statements in a file:

	$ gopls imports -w internal/cmd/check.go

imports-flags:
`)
	printFlagDefaults(f)
}

// Run performs diagnostic checks on the file specified and either;
// - if -w is specified, updates the file in place;
// - if -d is specified, prints out unified diffs of the changes; or
// - otherwise, prints the new versions to stdout.
func (t *imports) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("imports expects 1 argument")
	}
	t.app.editFlags = &t.EditFlags
	cli, _, err := t.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	uri := from.URI()
	file, err := cli.openFile(ctx, uri)
	if err != nil {
		return err
	}
	actions, err := cli.server.CodeAction(ctx, &protocol.CodeActionParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
		Context: protocol.CodeActionContext{
			Only: []protocol.CodeActionKind{protocol.SourceOrganizeImports},
		},
	})
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}
	var edits []protocol.TextEdit
	for _, a := range actions {
		for _, c := range a.Edit.DocumentChanges {
			// This code action should affect only the specified file;
			// it is safe to ignore others.
			if c.TextDocumentEdit != nil && c.TextDocumentEdit.TextDocument.URI == uri {
				edits = append(edits, protocol.AsTextEdits(c.TextDocumentEdit.Edits)...)
			}
		}
	}
	return applyTextEdits(file.mapper, edits, t.app.editFlags)
}


================================================
FILE: gopls/internal/cmd/info.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

// This file defines the help, bug, version, api-json, licenses commands.

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"io"
	"net/url"
	"os"
	"sort"
	"strings"

	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/doc"
	"golang.org/x/tools/gopls/internal/filecache"
	licensespkg "golang.org/x/tools/gopls/internal/licenses"
	"golang.org/x/tools/gopls/internal/util/browser"
	goplsbug "golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/tool"
)

// help implements the help command.
type help struct {
	app *Application
}

func (h *help) Name() string      { return "help" }
func (h *help) Parent() string    { return h.app.Name() }
func (h *help) Usage() string     { return "" }
func (h *help) ShortHelp() string { return "print usage information for subcommands" }
func (h *help) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `

Examples:
$ gopls help                         # main gopls help message
$ gopls help remote                  # help on 'remote' command
$ gopls help remote sessions         # help on 'remote sessions' subcommand
`)
	printFlagDefaults(f)
}

// Run prints help information about a subcommand.
func (h *help) Run(ctx context.Context, args ...string) error {
	find := func(cmds []tool.Application, name string) tool.Application {
		for _, cmd := range cmds {
			if cmd.Name() == name {
				return cmd
			}
		}
		return nil
	}

	// Find the subcommand denoted by args (empty => h.app).
	var cmd tool.Application = h.app
	for i, arg := range args {
		cmd = find(getSubcommands(cmd), arg)
		if cmd == nil {
			return tool.CommandLineErrorf(
				"no such subcommand: %s", strings.Join(args[:i+1], " "))
		}
	}

	// 'gopls help cmd subcmd' is equivalent to 'gopls cmd subcmd -h'.
	// The flag package prints the usage information (defined by tool.Run)
	// when it sees the -h flag.
	fs := flag.NewFlagSet(cmd.Name(), flag.ExitOnError)
	return tool.Run(ctx, fs, h.app, append(args[:len(args):len(args)], "-h"))
}

// version implements the version command.
type version struct {
	JSON bool `flag:"json" help:"outputs in json format."`

	app *Application
}

func (v *version) Name() string      { return "version" }
func (v *version) Parent() string    { return v.app.Name() }
func (v *version) Usage() string     { return "" }
func (v *version) ShortHelp() string { return "print the gopls version information" }
func (v *version) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), ``)
	printFlagDefaults(f)
}

// Run prints version information to stdout.
func (v *version) Run(ctx context.Context, args ...string) error {
	var mode = debug.PlainText
	if v.JSON {
		mode = debug.JSON
	}
	var buf bytes.Buffer
	debug.WriteVersionInfo(&buf, v.app.verbose(), mode)
	_, err := io.Copy(os.Stdout, &buf)
	return err
}

// bug implements the bug command.
type bug struct {
	app *Application
}

func (b *bug) Name() string      { return "bug" }
func (b *bug) Parent() string    { return b.app.Name() }
func (b *bug) Usage() string     { return "" }
func (b *bug) ShortHelp() string { return "report a bug in gopls" }
func (b *bug) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), ``)
	printFlagDefaults(f)
}

const goplsBugPrefix = "x/tools/gopls: <DESCRIBE THE PROBLEM>"
const goplsBugHeader = `ATTENTION: Please answer these questions BEFORE submitting your issue. Thanks!

#### What did you do?
If possible, provide a recipe for reproducing the error.
A complete runnable program is good.
A link on play.golang.org is better.
A failing unit test is the best.

#### What did you expect to see?


#### What did you see instead?


`

// Run collects some basic information and then prepares an issue ready to
// be reported.
func (b *bug) Run(ctx context.Context, args ...string) error {
	// This undocumented environment variable allows
	// the cmd integration test (and maintainers) to
	// trigger a call to bug.Report.
	if msg := os.Getenv("TEST_GOPLS_BUG"); msg != "" {
		filecache.Start() // register bug handler
		goplsbug.Report(msg)
		return nil
	}

	// Enumerate bug reports, grouped and sorted.
	_, reports := filecache.BugReports()
	sort.Slice(reports, func(i, j int) bool {
		x, y := reports[i], reports[i]
		if x.Key != y.Key {
			return x.Key < y.Key // ascending key order
		}
		return y.AtTime.Before(x.AtTime) // most recent first
	})
	keyDenom := make(map[string]int) // key is "file:line"
	for _, report := range reports {
		keyDenom[report.Key]++
	}

	// Privacy: the content of 'public' will be posted to GitHub
	// to populate an issue textarea. Even though the user must
	// submit the form to share the information with the world,
	// merely populating the form causes us to share the
	// information with GitHub itself.
	//
	// For that reason, we cannot write private information to
	// public, such as bug reports, which may quote source code.
	public := &bytes.Buffer{}
	fmt.Fprint(public, goplsBugHeader)
	if len(reports) > 0 {
		fmt.Fprintf(public, "#### Internal errors\n\n")
		fmt.Fprintf(public, "Gopls detected %d internal errors, %d distinct:\n",
			len(reports), len(keyDenom))
		for key, denom := range keyDenom {
			fmt.Fprintf(public, "- %s (%d)\n", key, denom)
		}
		fmt.Fprintf(public, "\nPlease copy the full information printed by `gopls bug` here, if you are comfortable sharing it.\n\n")
	}
	debug.WriteVersionInfo(public, true, debug.Markdown)
	body := public.String()
	title := strings.Join(args, " ")
	if !strings.HasPrefix(title, goplsBugPrefix) {
		title = goplsBugPrefix + title
	}
	if !browser.Open("https://github.com/golang/go/issues/new?title=" + url.QueryEscape(title) + "&body=" + url.QueryEscape(body)) {
		fmt.Print("Please file a new issue at golang.org/issue/new using this template:\n\n")
		fmt.Print(body)
	}

	// Print bug reports to stdout (not GitHub).
	keyNum := make(map[string]int)
	for _, report := range reports {
		fmt.Printf("-- %v -- \n", report.AtTime)

		// Append seq number (e.g. " (1/2)") for repeated keys.
		var seq string
		if denom := keyDenom[report.Key]; denom > 1 {
			keyNum[report.Key]++
			seq = fmt.Sprintf(" (%d/%d)", keyNum[report.Key], denom)
		}

		// Privacy:
		// - File and Stack may contain the name of the user that built gopls.
		// - Description may contain names of the user's packages/files/symbols.
		fmt.Printf("%s:%d: %s%s\n\n", report.File, report.Line, report.Description, seq)
		fmt.Printf("%s\n\n", report.Stack)
	}
	if len(reports) > 0 {
		fmt.Printf("Please copy the above information into the GitHub issue, if you are comfortable sharing it.\n")
	}

	return nil
}

type apiJSON struct {
	app *Application
}

func (j *apiJSON) Name() string      { return "api-json" }
func (j *apiJSON) Parent() string    { return j.app.Name() }
func (j *apiJSON) Usage() string     { return "" }
func (j *apiJSON) ShortHelp() string { return "print JSON describing gopls API" }
func (j *apiJSON) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
The api-json command prints a JSON value that describes
and documents all gopls' public interfaces.
Its schema is defined by golang.org/x/tools/gopls/internal/doc.API.
`)
	printFlagDefaults(f)
}

func (j *apiJSON) Run(ctx context.Context, args ...string) error {
	os.Stdout.WriteString(doc.JSON)
	fmt.Println()
	return nil
}

type licenses struct {
	app *Application
}

func (l *licenses) Name() string      { return "licenses" }
func (l *licenses) Parent() string    { return l.app.Name() }
func (l *licenses) Usage() string     { return "" }
func (l *licenses) ShortHelp() string { return "print licenses of included software" }
func (l *licenses) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), ``)
	printFlagDefaults(f)
}

const licensePreamble = `
gopls is made available under the following BSD-style license:

Copyright (c) 2009 The Go Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

gopls implements the LSP specification, which is made available under the following license:

Copyright (c) Microsoft Corporation

All rights reserved.

MIT License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED *AS IS*, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT
OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

gopls also includes software made available under these licenses:
`

func (l *licenses) Run(ctx context.Context, args ...string) error {
	txt := licensePreamble
	if licensespkg.Text == "" {
		txt += "(development gopls, license information not available)"
	} else {
		txt += licensespkg.Text
	}
	fmt.Fprint(os.Stdout, txt)
	return nil
}


================================================
FILE: gopls/internal/cmd/integration_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cmdtest contains the test suite for the command line behavior of gopls.
package cmd_test

// This file defines integration tests of each gopls subcommand that
// fork+exec the command in a separate process.
//
// (Rather than execute 'go build gopls' during the test, we reproduce
// the main entrypoint in the test executable.)
//
// The purpose of this test is to exercise client-side logic such as
// argument parsing and formatting of LSP RPC responses, not server
// behavior; see lsp_test for that.
//
// All tests run in parallel.
//
// TODO(adonovan):
// - Use markers to represent positions in the input and in assertions.
// - Coverage of cross-cutting things like cwd, environ, span parsing, etc.
// - Subcommands that accept -write and -diff flags implement them
//   consistently; factor their tests.
// - Add missing test for 'vulncheck' subcommand.
// - Add tests for client-only commands: serve, bug, help, api-json, licenses.

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"math/rand"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/cmd"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/version"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/tool"
	"golang.org/x/tools/txtar"
)

// TestVersion tests the 'version' subcommand (info.go).
func TestVersion(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, "")

	// There's not much we can robustly assert about the actual version.
	want := version.Version() // e.g. "master"

	// basic
	{
		res := gopls(t, tree, "version")
		res.checkExit(true)
		res.checkStdout(want)
	}

	// basic, with version override
	{
		res := goplsWithEnv(t, tree, []string{"TEST_GOPLS_VERSION=v1.2.3"}, "version")
		res.checkExit(true)
		res.checkStdout(`v1\.2\.3`)
	}

	// -json flag
	{
		res := gopls(t, tree, "version", "-json")
		res.checkExit(true)
		var v debug.ServerVersion
		if res.toJSON(&v) {
			if v.Version != want {
				t.Errorf("expected Version %q, got %q (%v)", want, v.Version, res)
			}
		}
	}
}

// TestCheck tests the 'check' subcommand (check.go).
func TestCheck(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
import "fmt"
var _ = fmt.Sprintf("%s", 123)

-- b.go --
package a
import "fmt"
var _ = fmt.Sprintf("%d", "123")
-- c/c.go --
package c
var C int
-- c/c2.go --
package c
var C int
-- d/d.go --
package d

import "io/ioutil"

var _ = ioutil.ReadFile
`)

	// no files
	{
		res := gopls(t, tree, "check")
		res.checkExit(true)
		if res.stdout != "" {
			t.Errorf("unexpected output: %v", res)
		}
	}

	// one file
	{
		res := gopls(t, tree, "check", "./a.go")
		res.checkExit(true)
		res.checkStdout("fmt.Sprintf format %s has arg 123 of wrong type int")
	}

	// two files
	{
		res := gopls(t, tree, "check", "./a.go", "./b.go")
		res.checkExit(true)
		res.checkStdout(`a.go:.* fmt.Sprintf format %s has arg 123 of wrong type int`)
		res.checkStdout(`b.go:.* fmt.Sprintf format %d has arg "123" of wrong type string`)
	}

	// diagnostic with related information spanning files
	{
		res := gopls(t, tree, "check", "./c/c2.go")
		res.checkExit(true)
		res.checkStdout(`c2.go:2:5-6: C redeclared in this block`)
		res.checkStdout(`c.go:2:5-6: - other declaration of C`)
	}

	// No deprecated (hint) diagnostic without -severity.
	{
		res := gopls(t, tree, "check", "./d/d.go")
		res.checkExit(true)
		if len(res.stdout) > 0 {
			t.Errorf("check ./d/d.go returned unexpected output:\n%s", res.stdout)
		}
	}

	// Deprecated (hint) diagnostics with -severity=hint
	{
		res := gopls(t, tree, "check", "-severity=hint", "./d/d.go")
		res.checkExit(true)
		res.checkStdout(`ioutil.ReadFile is deprecated`)
	}
}

// TestCallHierarchy tests the 'call_hierarchy' subcommand (call_hierarchy.go).
func TestCallHierarchy(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func f() {}
func g() {
	f()
}
func h() {
	f()
	f()
}
`)
	// missing position
	{
		res := gopls(t, tree, "call_hierarchy")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// wrong place
	{
		res := gopls(t, tree, "call_hierarchy", "a.go:1")
		res.checkExit(false)
		res.checkStderr("identifier not found")
	}
	// f is called once from g and twice from h.
	{
		res := gopls(t, tree, "call_hierarchy", "a.go:2:6")
		res.checkExit(true)
		// We use regexp '.' as an OS-agnostic path separator.
		res.checkStdout("ranges 7:2-3, 8:2-3 in ..a.go from/to function h in ..a.go:6:6-7")
		res.checkStdout("ranges 4:2-3 in ..a.go from/to function g in ..a.go:3:6-7")
		res.checkStdout("identifier: function f in ..a.go:2:6-7")
	}
}

// TestCodeLens tests the 'codelens' subcommand (codelens.go).
func TestCodeLens(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a
-- a/a_test.go --
package a_test
import "testing"
func TestPass(t *testing.T) {}
func TestFail(t *testing.T) { t.Fatal("fail") }
`)
	// missing position
	{
		res := gopls(t, tree, "codelens")
		res.checkExit(false)
		res.checkStderr("requires a file name")
	}
	// list code lenses
	{
		res := gopls(t, tree, "codelens", "./a/a_test.go")
		res.checkExit(true)
		res.checkStdout(`a_test.go:3: "run test" \[gopls.run_tests\]`)
		res.checkStdout(`a_test.go:4: "run test" \[gopls.run_tests\]`)
	}
	// no codelens with title/position
	{
		res := gopls(t, tree, "codelens", "-exec", "./a/a_test.go:1", "nope")
		res.checkExit(false)
		res.checkStderr(`no code lens at .* with title "nope"`)
	}
	// run the passing test
	{
		res := gopls(t, tree, "-v", "codelens", "-exec", "./a/a_test.go:3", "run test")
		res.checkExit(true)
		res.checkStderr(`PASS: TestPass`)         // from go test
		res.checkStderr("Info: all tests passed") // from gopls.test
	}
	// run the failing test
	{
		res := gopls(t, tree, "codelens", "-exec", "./a/a_test.go:4", "run test")
		res.checkExit(false)
		res.checkStderr(`FAIL	example.com/a`)
		res.checkStderr("Info: 1 / 1 tests failed")
	}
}

// TestDefinition tests the 'definition' subcommand (definition.go).
func TestDefinition(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
import "fmt"
func f() {
	fmt.Println()
}
func g() {
	f()
}
`)
	// missing position
	{
		res := gopls(t, tree, "definition")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// intra-package
	{
		res := gopls(t, tree, "definition", "a.go:7:2") // "f()"
		res.checkExit(true)
		res.checkStdout("a.go:3:6-7: defined here as func f")
	}
	// cross-package
	{
		res := gopls(t, tree, "definition", "a.go:4:7") // "Println"
		res.checkExit(true)
		res.checkStdout("print.go.* defined here as func fmt.Println")
		res.checkStdout("Println formats using the default formats for its operands")
	}
	// -json and -markdown
	{
		res := gopls(t, tree, "definition", "-json", "-markdown", "a.go:4:7")
		res.checkExit(true)
		var defn cmd.Definition
		if res.toJSON(&defn) {
			if !strings.HasPrefix(defn.Description, "```go\nfunc fmt.Println") {
				t.Errorf("Description does not start with markdown code block. Got: %s", defn.Description)
			}
		}
	}
}

// TestExecute tests the 'execute' subcommand (execute.go).
func TestExecute(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- hello.go --
package a
func main() {}

-- hello_test.go --
package a
import "testing"
func TestHello(t *testing.T) {
	t.Fatal("oops")
}
`)
	// missing command name
	{
		res := gopls(t, tree, "execute")
		res.checkExit(false)
		res.checkStderr("requires a command")
	}
	// bad command
	{
		res := gopls(t, tree, "execute", "gopls.foo")
		res.checkExit(false)
		res.checkStderr("unrecognized command: gopls.foo")
	}
	// too few arguments
	{
		res := gopls(t, tree, "execute", "gopls.run_tests")
		res.checkExit(false)
		res.checkStderr("expected 1 input arguments, got 0")
	}
	// too many arguments
	{
		res := gopls(t, tree, "execute", "gopls.run_tests", "null", "null")
		res.checkExit(false)
		res.checkStderr("expected 1 input arguments, got 2")
	}
	// argument is not JSON
	{
		res := gopls(t, tree, "execute", "gopls.run_tests", "hello")
		res.checkExit(false)
		res.checkStderr("argument 1 is not valid JSON: invalid character 'h'")
	}
	// add import, show diff
	hello := "file://" + filepath.ToSlash(tree) + "/hello.go"
	{
		res := gopls(t, tree, "execute", "-d", "gopls.add_import", `{"ImportPath": "fmt", "URI": "`+hello+`"}`)
		res.checkExit(true)
		res.checkStdout(`[+]import "fmt"`)
	}
	// list known packages (has a result)
	{
		res := gopls(t, tree, "execute", "gopls.list_known_packages", `{"URI": "`+hello+`"}`)
		res.checkExit(true)
		res.checkStdout(`"fmt"`)
		res.checkStdout(`"encoding/json"`)
	}
	// run tests
	{
		helloTest := "file://" + filepath.ToSlash(tree) + "/hello_test.go"
		res := gopls(t, tree, "execute", "gopls.run_tests", `{"URI": "`+helloTest+`", "Tests": ["TestHello"]}`)
		res.checkExit(false)
		res.checkStderr(`hello_test.go:4: oops`)
		res.checkStderr(`1 / 1 tests failed`)
	}
}

// TestFoldingRanges tests the 'folding_ranges' subcommand (folding_range.go).
func TestFoldingRanges(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func f(x int) {
	// hello
}
`)
	// missing filename
	{
		res := gopls(t, tree, "folding_ranges")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// success
	{
		res := gopls(t, tree, "folding_ranges", "a.go")
		res.checkExit(true)
		res.checkStdout("2:8-2:13") // params (x int)
		res.checkStdout("2:16-4:1") //   body { ... }
	}
}

// TestFormat tests the 'format' subcommand (format.go).
func TestFormat(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- a.go --
package a ;  func f ( ) { }
`)
	const want = `package a

func f() {}
`

	// no files => nop
	{
		res := gopls(t, tree, "format")
		res.checkExit(true)
	}
	// default => print formatted result
	{
		res := gopls(t, tree, "format", "a.go")
		res.checkExit(true)
		if res.stdout != want {
			t.Errorf("format: got <<%s>>, want <<%s>>", res.stdout, want)
		}
	}
	// start/end position not supported (unless equal to start/end of file)
	{
		res := gopls(t, tree, "format", "a.go:1-2")
		res.checkExit(false)
		res.checkStderr("only full file formatting supported")
	}
	// -list: show only file names
	{
		res := gopls(t, tree, "format", "-list", "a.go")
		res.checkExit(true)
		res.checkStdout("a.go")
	}
	// -diff prints a unified diff
	{
		res := gopls(t, tree, "format", "-diff", "a.go")
		res.checkExit(true)
		// We omit the filenames as they vary by OS.
		want := `
-package a ;  func f ( ) { }
+package a
+
+func f() {}
`
		res.checkStdout(regexp.QuoteMeta(want))
	}
	// -write updates the file
	{
		res := gopls(t, tree, "format", "-write", "a.go")
		res.checkExit(true)
		res.checkStdout("^$") // empty
		checkContent(t, filepath.Join(tree, "a.go"), want)
	}
}

// TestHighlight tests the 'highlight' subcommand (highlight.go).
func TestHighlight(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- a.go --
package a
import "fmt"
func f() {
	fmt.Println()
	fmt.Println()
}
`)

	// no arguments
	{
		res := gopls(t, tree, "highlight")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// all occurrences of Println
	{
		res := gopls(t, tree, "highlight", "a.go:4:7")
		res.checkExit(true)
		res.checkStdout("a.go:4:6-13")
		res.checkStdout("a.go:5:6-13")
	}
}

// TestImplementations tests the 'implementation' subcommand (implementation.go).
func TestImplementations(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- a.go --
package a
import "fmt"
type T int
func (T) String() string { return "" }
`)

	// no arguments
	{
		res := gopls(t, tree, "implementation")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// T.String
	{
		res := gopls(t, tree, "implementation", "a.go:4:10")
		res.checkExit(true)
		// TODO(adonovan): extract and check the content of the reported ranges?
		// We use regexp '.' as an OS-agnostic path separator.
		res.checkStdout("fmt.print.go:")     // fmt.Stringer.String
		res.checkStdout("runtime.error.go:") // runtime.stringer.String
	}
}

// TestImports tests the 'imports' subcommand (imports.go).
func TestImports(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- a.go --
package a
func _() {
	fmt.Println()
}
`)

	want := `
package a

import "fmt"
func _() {
	fmt.Println()
}
`[1:]

	// no arguments
	{
		res := gopls(t, tree, "imports")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// default: print with imports
	{
		res := gopls(t, tree, "imports", "a.go")
		res.checkExit(true)
		if res.stdout != want {
			t.Errorf("imports: got <<%s>>, want <<%s>>", res.stdout, want)
		}
	}
	// -diff: show a unified diff
	{
		res := gopls(t, tree, "imports", "-diff", "a.go")
		res.checkExit(true)
		res.checkStdout(regexp.QuoteMeta(`+import "fmt"`))
	}
	// -write: update file
	{
		res := gopls(t, tree, "imports", "-write", "a.go")
		res.checkExit(true)
		checkContent(t, filepath.Join(tree, "a.go"), want)
	}
}

// TestLinks tests the 'links' subcommand (links.go).
func TestLinks(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- a.go --
// Link in package doc: https://pkg.go.dev/
package a

// Link in internal comment: https://go.dev/cl

// Doc comment link: https://blog.go.dev/
func f() {}
`)
	// no arguments
	{
		res := gopls(t, tree, "links")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// success
	{
		res := gopls(t, tree, "links", "a.go")
		res.checkExit(true)
		res.checkStdout("https://go.dev/cl")
		res.checkStdout("https://pkg.go.dev")
		res.checkStdout("https://blog.go.dev/")
	}
	// -json
	{
		res := gopls(t, tree, "links", "-json", "a.go")
		res.checkExit(true)
		res.checkStdout("https://pkg.go.dev")
		res.checkStdout("https://go.dev/cl")
		res.checkStdout("https://blog.go.dev/") // at 5:21-5:41
		var links []protocol.DocumentLink
		if res.toJSON(&links) {
			// Check just one of the three locations.
			if got, want := fmt.Sprint(links[2].Range), "5:21-5:41"; got != want {
				t.Errorf("wrong link location: got %v, want %v", got, want)
			}
		}
	}
}

// TestReferences tests the 'references' subcommand (references.go).
func TestReferences(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
import "fmt"
func f() {
	fmt.Println()
}

-- b.go --
package a
import "fmt"
func g() {
	fmt.Println()
}
`)
	// no arguments
	{
		res := gopls(t, tree, "references")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// fmt.Println
	{
		res := gopls(t, tree, "references", "a.go:4:10")
		res.checkExit(true)
		res.checkStdout("a.go:4:6-13")
		res.checkStdout("b.go:4:6-13")
	}
}

// TestSignature tests the 'signature' subcommand (signature.go).
func TestSignature(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
import "fmt"
func f() {
	fmt.Println(123)
}
`)
	// no arguments
	{
		res := gopls(t, tree, "signature")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// at 123 inside fmt.Println() call
	{
		res := gopls(t, tree, "signature", "a.go:4:15")
		res.checkExit(true)
		res.checkStdout("Println\\(a ...")
		res.checkStdout("Println formats using the default formats...")
	}
}

// TestPrepareRename tests the 'prepare_rename' subcommand (prepare_rename.go).
func TestPrepareRename(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func oldname() {}
`)
	// no arguments
	{
		res := gopls(t, tree, "prepare_rename")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// in 'package' keyword
	{
		res := gopls(t, tree, "prepare_rename", "a.go:1:3")
		res.checkExit(false)
		res.checkStderr("request is not valid at the given position")
	}
	// in 'package' identifier (not supported by client)
	{
		res := gopls(t, tree, "prepare_rename", "a.go:1:9")
		res.checkExit(false)
		res.checkStderr("can't rename package")
	}
	// in func oldname
	{
		res := gopls(t, tree, "prepare_rename", "a.go:2:9")
		res.checkExit(true)
		res.checkStdout("a.go:2:6-13") // all of "oldname"
	}
}

// TestRename tests the 'rename' subcommand (rename.go).
func TestRename(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func oldname() {}
`)
	// no arguments
	{
		res := gopls(t, tree, "rename")
		res.checkExit(false)
		res.checkStderr("expects 2 arguments")
	}
	// missing newname
	{
		res := gopls(t, tree, "rename", "a.go:1:3")
		res.checkExit(false)
		res.checkStderr("expects 2 arguments")
	}
	// in 'package' keyword
	{
		res := gopls(t, tree, "rename", "a.go:1:3", "newname")
		res.checkExit(false)
		res.checkStderr("no identifier found")
	}
	// in 'package' identifier
	{
		res := gopls(t, tree, "rename", "a.go:1:9", "newname")
		res.checkExit(false)
		res.checkStderr(`cannot rename package: module path .* same as the package path, so .* no effect`)
	}
	// success, func oldname (and -diff)
	{
		res := gopls(t, tree, "rename", "-diff", "a.go:2:9", "newname")
		res.checkExit(true)
		res.checkStdout(regexp.QuoteMeta("-func oldname() {}"))
		res.checkStdout(regexp.QuoteMeta("+func newname() {}"))
	}
}

// TestSymbols tests the 'symbols' subcommand (symbols.go).
func TestSymbols(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func f()
var v int
const c = 0
`)
	// no files
	{
		res := gopls(t, tree, "symbols")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// success
	{
		res := gopls(t, tree, "symbols", "a.go:123:456") // (line/col ignored)
		res.checkExit(true)
		res.checkStdout("f Function 2:6-2:7")
		res.checkStdout("v Variable 3:5-3:6")
		res.checkStdout("c Constant 4:7-4:8")
	}
}

// TestSemtok tests the 'semtok' subcommand (semantictokens.go).
func TestSemtok(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func f()
var v int
const c = 0
`)
	// no files
	{
		res := gopls(t, tree, "semtok")
		res.checkExit(false)
		res.checkStderr("expected one file name")
	}
	// success
	{
		res := gopls(t, tree, "semtok", "a.go")
		res.checkExit(true)
		got := res.stdout
		want := `
/*⇒7,keyword,[]*/package /*⇒1,namespace,[]*/a
/*⇒4,keyword,[]*/func /*⇒1,function,[definition signature]*/f()
/*⇒3,keyword,[]*/var /*⇒1,variable,[definition static number]*/v /*⇒3,type,[defaultLibrary number]*/int
/*⇒5,keyword,[]*/const /*⇒1,variable,[definition readonly number]*/c = /*⇒1,number,[]*/0
`[1:]
		if got != want {
			t.Errorf("semtok: got <<%s>>, want <<%s>>", got, want)
		}
	}
}

func TestStats(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
-- b/b.go --
package b
-- testdata/foo.go --
package foo
`)

	// Trigger a bug report with a distinctive string
	// and check that it was durably recorded.
	oops := fmt.Sprintf("oops-%d", rand.Int())
	{
		env := []string{"TEST_GOPLS_BUG=" + oops}
		res := goplsWithEnv(t, tree, env, "bug")
		res.checkExit(true)
	}

	res := gopls(t, tree, "stats")
	res.checkExit(true)

	var stats cmd.GoplsStats
	if err := json.Unmarshal([]byte(res.stdout), &stats); err != nil {
		t.Fatalf("failed to unmarshal JSON output of stats command: %v", err)
	}

	// a few sanity checks
	checks := []struct {
		field string
		got   int
		want  int
	}{
		{
			"WorkspaceStats.Views[0].WorkspaceModules",
			stats.WorkspaceStats.Views[0].WorkspacePackages.Modules,
			1,
		},
		{
			"WorkspaceStats.Views[0].WorkspacePackages",
			stats.WorkspaceStats.Views[0].WorkspacePackages.Packages,
			2,
		},
		{"DirStats.Files", stats.DirStats.Files, 4},
		{"DirStats.GoFiles", stats.DirStats.GoFiles, 2},
		{"DirStats.ModFiles", stats.DirStats.ModFiles, 1},
		{"DirStats.TestdataFiles", stats.DirStats.TestdataFiles, 1},
	}
	for _, check := range checks {
		if check.got != check.want {
			t.Errorf("stats.%s = %d, want %d", check.field, check.got, check.want)
		}
	}

	// Check that we got a BugReport with the expected message.
	{
		got := fmt.Sprint(stats.BugReports)
		wants := []string{
			"cmd/info.go", // File containing call to bug.Report
			oops,          // Description
		}
		for _, want := range wants {
			if !strings.Contains(got, want) {
				t.Errorf("BugReports does not contain %q. Got:<<%s>>", want, got)
				break
			}
		}
	}

	// Check that -anon suppresses fields containing user information.
	{
		res2 := gopls(t, tree, "stats", "-anon")
		res2.checkExit(true)

		var stats2 cmd.GoplsStats
		if err := json.Unmarshal([]byte(res2.stdout), &stats2); err != nil {
			t.Fatalf("failed to unmarshal JSON output of stats command: %v", err)
		}
		if got := len(stats2.BugReports); got > 0 {
			t.Errorf("Got %d bug reports with -anon, want 0. Reports:%+v", got, stats2.BugReports)
		}
		var stats2AsMap map[string]any
		if err := json.Unmarshal([]byte(res2.stdout), &stats2AsMap); err != nil {
			t.Fatalf("failed to unmarshal JSON output of stats command: %v", err)
		}
		// GOPACKAGESDRIVER is user information, but is ok to print zero value.
		if v, ok := stats2AsMap["GOPACKAGESDRIVER"]; ok && v != "" {
			t.Errorf(`Got GOPACKAGESDRIVER=(%v, %v); want ("", true(found))`, v, ok)
		}
	}

	// Check that -anon suppresses fields containing non-zero user information.
	{
		res3 := goplsWithEnv(t, tree, []string{"GOPACKAGESDRIVER=off"}, "stats", "-anon")
		res3.checkExit(true)

		var statsAsMap3 map[string]any
		if err := json.Unmarshal([]byte(res3.stdout), &statsAsMap3); err != nil {
			t.Fatalf("failed to unmarshal JSON output of stats command: %v", err)
		}
		// GOPACKAGESDRIVER is user information, want non-empty value to be omitted.
		if v, ok := statsAsMap3["GOPACKAGESDRIVER"]; ok {
			t.Errorf(`Got GOPACKAGESDRIVER=(%q, %v); want ("", false(not found))`, v, ok)
		}
	}
}

// TestCodeAction tests the 'codeaction' subcommand (codeaction.go).
func TestCodeAction(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a
type T int
func f() (int, string) { return }

-- a/b.go --
package a
import "io"
var _ io.Reader = C{}
type C struct{}
`)

	// no arguments
	{
		res := gopls(t, tree, "codeaction")
		res.checkExit(false)
		res.checkStderr("expects at least 1 argument")
	}
	// list code actions in file
	{
		res := gopls(t, tree, "codeaction", "a/a.go")
		res.checkExit(true)
		res.checkStdout(`edit	"Fill in return values" \[quickfix\]`)
		res.checkStdout(`command	"Browse documentation for package a" \[source.doc\]`)
	}
	// list code actions in file, filtering by title
	{
		res := gopls(t, tree, "codeaction", "-title=Browse.*doc", "a/a.go")
		res.checkExit(true)
		got := res.stdout
		want := `command	"Browse documentation for package a" [source.doc]` +
			"\n" +
			`command	"Browse gopls feature documentation" [gopls.doc.features]` +
			"\n"
		if got != want {
			t.Errorf("codeaction: got <<%s>>, want <<%s>>\nstderr:\n%s", got, want, res.stderr)
		}
	}
	// list code actions in file, filtering (hierarchically) by kind
	{
		res := gopls(t, tree, "codeaction", "-kind=source", "a/a.go")
		res.checkExit(true)
		got := res.stdout
		want := `command	"Browse documentation for package a" [source.doc]` +
			"\n" +
			`command	"Split package \"a\"" [source.splitPackage]` +
			"\n" +
			`command	"Show compiler optimization details for \"a\"" [source.toggleCompilerOptDetails]` +
			"\n"
		if got != want {
			t.Errorf("codeaction: got <<%s>>, want <<%s>>\nstderr:\n%s", got, want, res.stderr)
		}
	}
	// list code actions at position (of io.Reader)
	{
		res := gopls(t, tree, "codeaction", "a/b.go:#31")
		res.checkExit(true)
		res.checkStdout(`command	"Browse documentation for type io.Reader" \[source.doc]`)
	}
	// list quick fixes at position (of type T)
	{
		res := gopls(t, tree, "codeaction", "-kind=quickfix", "a/a.go:#15")
		res.checkExit(true)
		got := res.stdout
		want := `edit	"Fill in return values" [quickfix]` + "\n"
		if got != want {
			t.Errorf("codeaction: got <<%s>>, want <<%s>>\nstderr:\n%s", got, want, res.stderr)
		}
	}
	// success, with explicit CodeAction kind and diagnostics span.
	{
		res := gopls(t, tree, "codeaction", "-kind=quickfix", "-exec", "a/b.go:#40")
		res.checkExit(true)
		got := res.stdout
		want := `
package a

import "io"

var _ io.Reader = C{}

type C struct{}

// Read implements [io.Reader].
func (c C) Read(p []byte) (n int, err error) {
	panic("unimplemented")
}
`[1:]
		if got != want {
			t.Errorf("codeaction: got <<%s>>, want <<%s>>\nstderr:\n%s", got, want, res.stderr)
		}
	}
}

// TestWorkspaceSymbol tests the 'workspace_symbol' subcommand (workspace_symbol.go).
func TestWorkspaceSymbol(t *testing.T) {
	t.Parallel()

	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package a
func someFunctionName()
`)
	// no files
	{
		res := gopls(t, tree, "workspace_symbol")
		res.checkExit(false)
		res.checkStderr("expects 1 argument")
	}
	// success
	{
		res := gopls(t, tree, "workspace_symbol", "meFun")
		res.checkExit(true)
		res.checkStdout("a.go:2:6-22 someFunctionName Function")
	}
}

// -- test framework --

func TestMain(m *testing.M) {
	switch os.Getenv("ENTRYPOINT") {
	case "goplsMain":
		goplsMain()
	default:
		os.Exit(m.Run())
	}
}

// This function is a stand-in for gopls.main in ../../../../main.go.
func goplsMain() {
	// Panic on bugs (unlike the production gopls command),
	// except in tests that inject calls to bug.Report.
	if os.Getenv("TEST_GOPLS_BUG") == "" {
		bug.PanicOnBugs = true
	}

	if v := os.Getenv("TEST_GOPLS_VERSION"); v != "" {
		version.VersionOverride = v
	}

	tool.Main(context.Background(), cmd.New(), os.Args[1:])
}

// writeTree extracts a txtar archive into a new directory and returns its path.
func writeTree(t *testing.T, archive string) string {
	root := t.TempDir()

	// This unfortunate step is required because gopls output
	// expands symbolic links in its input file names (arguably it
	// should not), and on macOS the temp dir is in /var -> private/var.
	root, err := filepath.EvalSymlinks(root)
	if err != nil {
		t.Fatal(err)
	}

	for _, f := range txtar.Parse([]byte(archive)).Files {
		filename := filepath.Join(root, f.Name)
		if err := os.MkdirAll(filepath.Dir(filename), 0777); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(filename, f.Data, 0666); err != nil {
			t.Fatal(err)
		}
	}
	return root
}

// gopls executes gopls in a child process.
func gopls(t *testing.T, dir string, args ...string) *result {
	return goplsWithEnv(t, dir, nil, args...)
}

func goplsWithEnv(t *testing.T, dir string, env []string, args ...string) *result {
	testenv.NeedsTool(t, "go")

	// Catch inadvertent use of dir=".", which would make
	// the ReplaceAll below unpredictable.
	if !filepath.IsAbs(dir) {
		t.Fatalf("dir is not absolute: %s", dir)
	}

	goplsCmd := exec.Command(os.Args[0], args...)
	goplsCmd.Env = append(os.Environ(), "ENTRYPOINT=goplsMain")
	goplsCmd.Env = append(goplsCmd.Env, "GOPACKAGESDRIVER=off")
	goplsCmd.Env = append(goplsCmd.Env, env...)
	goplsCmd.Dir = dir
	goplsCmd.Stdout = new(bytes.Buffer)
	goplsCmd.Stderr = new(bytes.Buffer)

	cmdErr := goplsCmd.Run()

	stdout := strings.ReplaceAll(fmt.Sprint(goplsCmd.Stdout), dir, ".")
	stderr := strings.ReplaceAll(fmt.Sprint(goplsCmd.Stderr), dir, ".")
	exitcode := 0
	if cmdErr != nil {
		if exitErr, ok := cmdErr.(*exec.ExitError); ok {
			exitcode = exitErr.ExitCode()
		} else {
			stderr = cmdErr.Error() // (execve failure)
			exitcode = -1
		}
	}
	res := &result{
		t:        t,
		command:  "gopls " + strings.Join(args, " "),
		exitcode: exitcode,
		stdout:   stdout,
		stderr:   stderr,
	}
	if false {
		t.Log(res)
	}
	return res
}

// A result holds the result of a gopls invocation, and provides assertion helpers.
type result struct {
	t              *testing.T
	command        string
	exitcode       int
	stdout, stderr string
}

func (res *result) String() string {
	return fmt.Sprintf("%s: exit=%d stdout=<<%s>> stderr=<<%s>>",
		res.command, res.exitcode, res.stdout, res.stderr)
}

// checkExit asserts that gopls returned the expected exit code.
func (res *result) checkExit(success bool) {
	res.t.Helper()
	if (res.exitcode == 0) != success {
		res.t.Errorf("%s: exited with code %d, want success: %t (%s)",
			res.command, res.exitcode, success, res)
	}
}

// checkStdout asserts that the gopls standard output matches the pattern.
func (res *result) checkStdout(pattern string) {
	res.t.Helper()
	res.checkOutput(pattern, "stdout", res.stdout)
}

// checkStderr asserts that the gopls standard error matches the pattern.
func (res *result) checkStderr(pattern string) {
	res.t.Helper()
	res.checkOutput(pattern, "stderr", res.stderr)
}

func (res *result) checkOutput(pattern, name, content string) {
	res.t.Helper()
	if match, err := regexp.MatchString(pattern, content); err != nil {
		res.t.Errorf("invalid regexp: %v", err)
	} else if !match {
		res.t.Errorf("%s: %s does not match [%s]; got <<%s>>",
			res.command, name, pattern, content)
	}
}

// toJSON decodes res.stdout as JSON into to *ptr and reports its success.
func (res *result) toJSON(ptr any) bool {
	if err := json.Unmarshal([]byte(res.stdout), ptr); err != nil {
		res.t.Errorf("invalid JSON %v", err)
		return false
	}
	return true
}

// checkContent checks that the contents of the file are as expected.
func checkContent(t *testing.T, filename, want string) {
	data, err := os.ReadFile(filename)
	if err != nil {
		t.Error(err)
		return
	}
	if got := string(data); got != want {
		t.Errorf("content of %s is <<%s>>, want <<%s>>", filename, got, want)
	}
}


================================================
FILE: gopls/internal/cmd/links.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"os"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// links implements the links verb for gopls.
type links struct {
	JSON bool `flag:"json" help:"emit document links in JSON format"`

	app *Application
}

func (l *links) Name() string      { return "links" }
func (l *links) Parent() string    { return l.app.Name() }
func (l *links) Usage() string     { return "[links-flags] <filename>" }
func (l *links) ShortHelp() string { return "list links in a file" }
func (l *links) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprintf(f.Output(), `
Example: list links contained within a file:

	$ gopls links internal/cmd/check.go

links-flags:
`)
	printFlagDefaults(f)
}

// Run finds all the links within a document
// - if -json is specified, outputs location range and uri
// - otherwise, prints the a list of unique links
func (l *links) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("links expects 1 argument")
	}
	cli, _, err := l.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	uri := from.URI()

	if _, err := cli.openFile(ctx, uri); err != nil {
		return err
	}
	results, err := cli.server.DocumentLink(ctx, &protocol.DocumentLinkParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
	})
	if err != nil {
		return fmt.Errorf("%v: %v", from, err)
	}
	if l.JSON {
		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "\t")
		return enc.Encode(results)
	}
	for _, v := range results {
		fmt.Println(*v.Target)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/mcp.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"sync"
	"time"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/filewatcher"
	internalmcp "golang.org/x/tools/gopls/internal/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
)

type headlessMCP struct {
	app *Application

	Address      string `flag:"listen" help:"the address on which to run the mcp server"`
	Logfile      string `flag:"logfile" help:"filename to log to; if unset, logs to stderr"`
	RPCTrace     bool   `flag:"rpc.trace" help:"print MCP rpc traces; cannot be used with -listen"`
	Instructions bool   `flag:"instructions" help:"if set, print gopls' MCP instructions and exit"`
}

func (m *headlessMCP) Name() string      { return "mcp" }
func (m *headlessMCP) Parent() string    { return m.app.Name() }
func (m *headlessMCP) Usage() string     { return "[mcp-flags]" }
func (m *headlessMCP) ShortHelp() string { return "start the gopls MCP server in headless mode" }

func (m *headlessMCP) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Starts the gopls MCP server in headless mode, without needing an LSP client.
Starts the server over stdio or sse with http, depending on whether the listen flag is provided.

Examples:
  $ gopls mcp -listen=localhost:3000
  $ gopls mcp  //start over stdio
`)
	printFlagDefaults(f)
}

func (m *headlessMCP) Run(ctx context.Context, args ...string) error {
	if m.Instructions {
		fmt.Println(internalmcp.Instructions)
		return nil
	}
	if m.Address != "" && m.RPCTrace {
		// There's currently no way to plumb logging instrumentation into the SSE
		// transport that is created on connections to the HTTP handler, so we must
		// disallow the -rpc.trace flag when using -listen.
		return fmt.Errorf("-listen is incompatible with -rpc.trace")
	}
	if m.Logfile != "" {
		f, err := os.Create(m.Logfile)
		if err != nil {
			return fmt.Errorf("opening logfile: %v", err)
		}
		log.SetOutput(f)
		defer f.Close()
	}

	// Start a new in-process gopls session and create a fake client
	// to connect to it.
	cli, sess, err := m.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	var (
		queueMu  sync.Mutex
		queue    []protocol.FileEvent
		nonempty = make(chan struct{}) // receivable when len(queue) > 0
		stop     = make(chan struct{}) // closed when Run returns
	)
	defer close(stop)

	// This goroutine forwards file change events to the LSP server.
	go func() {
		for {
			select {
			case <-stop:
				return
			case <-nonempty:
				queueMu.Lock()
				q := queue
				queue = nil
				queueMu.Unlock()

				if len(q) > 0 {
					if err := cli.server.DidChangeWatchedFiles(ctx, &protocol.DidChangeWatchedFilesParams{
						Changes: q,
					}); err != nil {
						log.Printf("failed to notify changed files: %v", err)
					}
				}

			}
		}
	}()

	errHandler := func(err error) {
		log.Printf("watch error: %v", err)
	}
	w, err := filewatcher.New("fsnotify", 500*time.Millisecond, nil, func(events []protocol.FileEvent) {
		if len(events) == 0 {
			return
		}

		// Since there is no promise [protocol.Server.DidChangeWatchedFiles]
		// will return immediately, we should buffer the captured events and
		// sent them whenever available in a separate go routine.
		queueMu.Lock()
		queue = append(queue, events...)
		queueMu.Unlock()

		select {
		case nonempty <- struct{}{}:
		default:
		}
	}, errHandler)
	if err != nil {
		return err
	}
	defer w.Close()

	// TODO(hxjiang): in LSP's use case, the file watcher should watch for LSP
	// initial param workspace root.

	// TODO(hxjiang): refactor the queue pattern into a helper function to avoid
	// repetition.
	var (
		watchStop          = make(chan struct{}) // closed to broadcast "stop" event
		watchQueueNonempty = make(chan struct{}) // each send indicates "nonempty"
		watchQueueMu       sync.Mutex
		watchQueue         []string
	)
	// The watchStop event occurs when this function returns,
	// for any reason (cancellation or completion).
	defer close(watchStop)

	// TODO(hxjiang): memorize the roots and stop watching when the previously
	// watched roots are removed.
	// TODO(hxjiang): implement [filewatcher.Watcher]'s method StopWatchDir.

	// watchRoots is the callback triggered when the MCP client reports workspace
	// roots. We do not call w.WatchDir directly from this callback, but spawn a
	// goroutine for it because WatchDir performs OS-level filesystem operations
	// which can be slow. Blocking this callback would block the MCP server's
	// JSON-RPC message loop and stall the entireconnection.
	watchRoots := func(res *mcp.ListRootsResult, err error) {
		if err != nil {
			errHandler(err)
			return
		}
		watchQueueMu.Lock()
		for _, r := range res.Roots {
			watchQueue = append(watchQueue, protocol.DocumentURI(r.URI).Path())
		}
		watchQueueMu.Unlock()

		select {
		case watchQueueNonempty <- struct{}{}:
		default:
		}
	}
	go func() {
		for {
			select {
			case <-watchStop:
				return
			case <-watchQueueNonempty:
				watchQueueMu.Lock()
				queue := watchQueue
				watchQueue = nil
				watchQueueMu.Unlock()

				for _, dir := range queue {
					if err := w.WatchDir(dir); err != nil {
						errHandler(err)
					}
				}
			}
		}
	}()

	if m.Address != "" {
		countHeadlessMCPSSE.Inc()
		return internalmcp.Serve(ctx, m.Address, &staticSessions{sess, cli.server}, false, watchRoots)
	} else {
		countHeadlessMCPStdIO.Inc()
		var rpcLog io.Writer
		if m.RPCTrace {
			rpcLog = log.Writer() // possibly redirected by -logfile above
		}
		log.Printf("Listening for MCP messages on stdin...")
		return internalmcp.StartStdIO(ctx, sess, cli.server, rpcLog, watchRoots)
	}
}

// staticSessions implements the [internalmcp.Sessions] interface for a single gopls
// session.
type staticSessions struct {
	session *cache.Session
	server  protocol.Server
}

func (s *staticSessions) SetSessionExitFunc(func(string)) {}

func (s *staticSessions) FirstSession() (*cache.Session, protocol.Server) {
	return s.session, s.server
}

func (s *staticSessions) Session(id string) (*cache.Session, protocol.Server) {
	if s.session.ID() == id {
		return s.session, s.server
	}
	return nil, nil
}


================================================
FILE: gopls/internal/cmd/mcp_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd_test

import (
	"bufio"
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"slices"
	"strconv"
	"strings"
	"testing"
	"time"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	goplsmcp "golang.org/x/tools/gopls/internal/mcp"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/vulncheck/vulntest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

func TestMCPCommandStdio(t *testing.T) {
	// Test that the headless MCP subcommand works, and recognizes file changes.
	if !supportsFsnotify(runtime.GOOS) {
		// See golang/go#74580
		t.Skipf("skipping on %s; fsnotify is not supported", runtime.GOOS)
	}
	testenv.NeedsExec(t) // stdio transport uses execve(2)
	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package p

const A = 1

-- b.go --
package p

const B = 2
`)

	goplsCmd := exec.Command(os.Args[0], "mcp")
	goplsCmd.Env = append(os.Environ(), "ENTRYPOINT=goplsMain")
	goplsCmd.Dir = tree
	goplsCmd.Stderr = t.Output() // to debug https://go.dev/issue/77334

	ctx := t.Context()
	client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
	mcpSession, err := client.Connect(ctx, &mcp.CommandTransport{Command: goplsCmd}, nil)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := mcpSession.Close(); err != nil {
			t.Errorf("closing MCP connection: %v", err)
		}
	}()
	var (
		tool = "go_diagnostics"
		args = map[string]any{"files": []string{filepath.Join(tree, "a.go")}}
	)
	// On the first diagnostics call, there should be no diagnostics.
	{
		// Match on a substring of the expected output from the context tool.
		res, err := mcpSession.CallTool(ctx, &mcp.CallToolParams{Name: tool, Arguments: args})
		if err != nil {
			t.Fatal(err)
		}
		got := resultText(t, res)
		want := "No diagnostics"
		if !strings.Contains(got, want) {
			t.Errorf("CallTool(%s, %v) = %v, want containing %q", tool, args, got, want)
		}
	}
	// Now, create a duplicate diagnostic in "b.go", and expect that the headless
	// MCP server detects the file change. In order to guarantee that the change
	// is detected, sleep long to ensure a different mtime.
	time.Sleep(100 * time.Millisecond)
	newContent := "package p\n\nconst A = 2\n"
	if err := os.WriteFile(filepath.Join(tree, "b.go"), []byte(newContent), 0666); err != nil {
		t.Fatal(err)
	}
	{
		res, err := mcpSession.CallTool(ctx, &mcp.CallToolParams{Name: tool, Arguments: args})
		if err != nil {
			t.Fatal(err)
		}
		got := resultText(t, res)
		want := "redeclared"
		if !strings.Contains(got, want) {
			t.Errorf("CallTool(%s, %v) = %v, want containing %q", tool, args, got, want)
		}
	}
}

func TestMCPCommandLogging(t *testing.T) {
	// Test that logging flags for headless MCP subcommand work as intended.
	if !supportsFsnotify(runtime.GOOS) {
		// See golang/go#74580
		t.Skipf("skipping on %s; fsnotify is not supported", runtime.GOOS)
	}
	testenv.NeedsExec(t) // stdio transport uses execve(2)

	tests := []struct {
		logFile  string // also the subtest name
		trace    bool
		want     string
		dontWant string
	}{
		{"notrace.log", false, "stdin", "initialized"},
		{"trace.log", true, "initialized", ""},
	}

	dir := t.TempDir()
	for _, test := range tests {
		t.Run(test.logFile, func(t *testing.T) {
			tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18

-- a.go --
package p
`)

			logFile := filepath.Join(dir, test.logFile)
			args := []string{"mcp", "-logfile", logFile}
			if test.trace {
				args = append(args, "-rpc.trace")
			}
			goplsCmd := exec.Command(os.Args[0], args...)
			goplsCmd.Env = append(os.Environ(), "ENTRYPOINT=goplsMain")
			goplsCmd.Dir = tree
			goplsCmd.Stderr = t.Output() // to debug https://go.dev/issue/77334

			ctx := t.Context()
			client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
			mcpSession, err := client.Connect(ctx, &mcp.CommandTransport{Command: goplsCmd}, nil)
			if err != nil {
				t.Fatal(err)
			}
			if err := mcpSession.Close(); err != nil {
				t.Errorf("closing MCP connection: %v", err)
			}
			logs, err := os.ReadFile(logFile)
			if err != nil {
				t.Fatal(err)
			}
			if test.want != "" && !bytes.Contains(logs, []byte(test.want)) {
				t.Errorf("logs do not contain expected %q", test.want)
			}
			if test.dontWant != "" && bytes.Contains(logs, []byte(test.dontWant)) {
				t.Errorf("logs contain unexpected %q", test.dontWant)
			}
			if t.Failed() {
				t.Logf("Logs:\n%s", string(logs))
			}
		})
	}
}

func TestMCPCommandHTTP(t *testing.T) {
	if !supportsFsnotify(runtime.GOOS) {
		// See golang/go#74580
		t.Skipf("skipping on %s; fsnotify is not supported", runtime.GOOS)
	}
	testenv.NeedsExec(t)
	tree := writeTree(t, `
-- go.mod --
module example.com
go 1.18
-- a.go --
package a

import "example.com/b"

-- b/b.go --
package b

func MyFun() {}
`)
	port := strconv.Itoa(getRandomPort())
	addr := "localhost:" + port
	goplsCmd := exec.Command(os.Args[0], "-v", "mcp", "-listen="+addr)
	goplsCmd.Env = append(os.Environ(), "ENTRYPOINT=goplsMain")
	goplsCmd.Dir = tree
	goplsCmd.Stdout = os.Stderr

	// Pipe stderr to a scanner, so that we can wait for the log message that
	// tells us the server has started.
	stderr, err := goplsCmd.StderrPipe()
	if err != nil {
		t.Fatal(err)
	}
	// forward stdout to test output
	if err := goplsCmd.Start(); err != nil {
		t.Fatalf("starting gopls: %v", err)
	}
	defer func() {
		if err := goplsCmd.Process.Kill(); err != nil {
			t.Fatalf("killing gopls: %v", err)
		}
		// Wait for the gopls process to exit before we return and the test framework
		// attempts to clean up the temporary directory.
		// We expect an error because we killed the process.
		goplsCmd.Wait()
	}()

	// Wait for the MCP server to start listening. The referenced log occurs
	// after the connection is opened via net.Listen and the HTTP handlers are
	// set up.
	ready := make(chan bool)
	go func() {
		// Copy from the pipe to stderr, keeping an eye out for the "mcp http
		// server listening" string.
		scan := bufio.NewScanner(stderr)
		for scan.Scan() {
			line := scan.Text()
			if strings.Contains(line, "mcp http server listening") {
				ready <- true
			}
			fmt.Fprintln(os.Stderr, line)
		}
		if err := scan.Err(); err != nil {
			t.Logf("reading from pipe: %v", err)
		}
	}()

	<-ready
	client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
	ctx := t.Context()
	mcpSession, err := client.Connect(ctx, &mcp.SSEClientTransport{Endpoint: "http://" + addr}, nil)
	if err != nil {
		t.Fatalf("connecting to server: %v", err)
	}
	defer func() {
		if err := mcpSession.Close(); err != nil {
			t.Errorf("closing MCP connection: %v", err)
		}
	}()

	var (
		tool = "go_file_context"
		args = map[string]any{"file": filepath.Join(tree, "a.go")}
	)
	res, err := mcpSession.CallTool(ctx, &mcp.CallToolParams{Name: tool, Arguments: args})
	if err != nil {
		t.Fatal(err)
	}
	got := resultText(t, res)
	want := "example.com"
	if !strings.Contains(got, want) {
		t.Errorf("CallTool(%s, %v) = %+v, want containing %q", tool, args, got, want)
	}
}

func TestMCPVulncheckCommand(t *testing.T) {
	if !supportsFsnotify(runtime.GOOS) {
		// See golang/go#74580
		t.Skipf("skipping on %s; fsnotify is not supported", runtime.GOOS)
	}
	testenv.NeedsTool(t, "go")
	const proxyData = `
-- example.com/vulnmod@v1.0.0/go.mod --
module example.com/vulnmod
go 1.18
-- example.com/vulnmod@v1.0.0/vuln.go --
package vulnmod

// VulnFunc is a vulnerable function.
func VulnFunc() {}
`
	const vulnData = `
-- GO-TEST-0001.yaml --
modules:
  - module: example.com/vulnmod
    versions:
      - introduced: "1.0.0"
    packages:
      - package: example.com/vulnmod
        symbols:
          - VulnFunc
`
	proxyArchive := txtar.Parse([]byte(proxyData))
	proxyFiles := make(map[string][]byte)
	for _, f := range proxyArchive.Files {
		proxyFiles[f.Name] = f.Data
	}
	goproxy, err := fake.WriteProxy(t.TempDir(), proxyFiles)
	if err != nil {
		t.Fatal(err)
	}

	db, err := vulntest.NewDatabase(context.Background(), []byte(vulnData))
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()

	tree := writeTree(t, `
-- go.mod --
module example.com/user
go 1.18
require example.com/vulnmod v1.0.0
-- main.go --
package main
import "example.com/vulnmod"
func main() {
	vulnmod.VulnFunc()
}
`)

	// Update go.sum before running gopls, to avoid load failures.
	tidyCmd := exec.CommandContext(t.Context(), "go", "mod", "tidy")
	tidyCmd.Dir = tree
	tidyCmd.Env = append(os.Environ(), "GOPROXY="+goproxy, "GOSUMDB=off")
	if output, err := tidyCmd.CombinedOutput(); err != nil {
		t.Fatalf("go mod tidy failed: %v\n%s", err, output)
	}

	goplsCmd := exec.Command(os.Args[0], "mcp")
	goplsCmd.Env = append(os.Environ(),
		"ENTRYPOINT=goplsMain",
		"GOPROXY="+goproxy,
		"GOSUMDB=off",
		"GOVULNDB="+db.URI(),
	)
	goplsCmd.Dir = tree
	goplsCmd.Stderr = t.Output() // to debug https://go.dev/issue/77334

	ctx := t.Context()
	client := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
	mcpSession, err := client.Connect(ctx, &mcp.CommandTransport{Command: goplsCmd}, nil)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := mcpSession.Close(); err != nil {
			t.Errorf("closing MCP connection: %v", err)
		}
	}()

	res, err := mcpSession.CallTool(ctx, &mcp.CallToolParams{Name: "go_vulncheck", Arguments: map[string]any{}})
	if err != nil {
		t.Fatal(err)
	}
	jsonBytes, err := json.Marshal(res.StructuredContent)
	if err != nil {
		t.Fatal(err)
	}

	var result goplsmcp.VulncheckResultOutput
	if err := json.Unmarshal(jsonBytes, &result); err != nil {
		t.Fatal(err)
	}
	if len(result.Findings) != 1 {
		t.Errorf("expected 1 finding, got %d", len(result.Findings))
	} else {
		finding := result.Findings[0]
		if finding.ID != "GO-TEST-0001" {
			t.Errorf("expected ID 'GO-TEST-0001', got %q", finding.ID)
		}
		expectedPackages := []string{"Go standard library", "example.com/vulnmod"}
		if !slices.Equal(finding.AffectedPackages, expectedPackages) {
			t.Errorf("expected affected packages %v, got %v", expectedPackages, finding.AffectedPackages)
		}
	}

	if result.Logs == "" {
		t.Errorf("expected logs to be non-empty")
	} else {
		t.Logf("Logs:\n%s", result.Logs)
	}
}

// resultText concatenates the textual content of the given result, reporting
// an error if any content values are non-textual.
func resultText(t *testing.T, res *mcp.CallToolResult) string {
	t.Helper()

	var buf bytes.Buffer
	for _, content := range res.Content {
		if c, ok := content.(*mcp.TextContent); ok {
			fmt.Fprintf(&buf, "%s\n", c.Text)
		} else {
			t.Errorf("Not text content: %T", content)
		}
	}
	return buf.String()
}

// getRandomPort returns the number of a random available port. Inherently racy:
// nothing stops another process from listening on it - but this should be fine
// for testing purposes.
func getRandomPort() int {
	listener, err := net.Listen("tcp", "localhost:0")
	if err != nil {
		panic(err)
	}
	defer listener.Close()
	return listener.Addr().(*net.TCPAddr).Port
}

// supportsFsnotify returns true if fsnotify supports the os.
func supportsFsnotify(os string) bool {
	return os == "darwin" || os == "linux" || os == "windows"
}


================================================
FILE: gopls/internal/cmd/parsespan.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"strconv"
	"strings"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/protocol"
)

// parseSpan returns the location represented by the input.
// Only file paths are accepted, not URIs.
// The returned span will be normalized, and thus if printed may produce a
// different string.
func parseSpan(input string) span {
	uri := protocol.URIFromPath

	// :0:0#0-0:0#0
	valid := input
	var hold, offset int
	hadCol := false
	suf := rstripSuffix(input)
	if suf.sep == "#" {
		offset = suf.num
		suf = rstripSuffix(suf.remains)
	}
	if suf.sep == ":" {
		valid = suf.remains
		hold = suf.num
		hadCol = true
		suf = rstripSuffix(suf.remains)
	}
	switch {
	case suf.sep == ":":
		return newSpan(uri(suf.remains), newPoint(suf.num, hold, offset), point{})
	case suf.sep == "-":
		// we have a span, fall out of the case to continue
	default:
		// separator not valid, rewind to either the : or the start
		return newSpan(uri(valid), newPoint(hold, 0, offset), point{})
	}
	// only the span form can get here
	// at this point we still don't know what the numbers we have mean
	// if have not yet seen a : then we might have either a line or a column depending
	// on whether start has a column or not
	// we build an end point and will fix it later if needed
	end := newPoint(suf.num, hold, offset)
	hold, offset = 0, 0
	suf = rstripSuffix(suf.remains)
	if suf.sep == "#" {
		offset = suf.num
		suf = rstripSuffix(suf.remains)
	}
	if suf.sep != ":" {
		// turns out we don't have a span after all, rewind
		return newSpan(uri(valid), end, point{})
	}
	valid = suf.remains
	hold = suf.num
	suf = rstripSuffix(suf.remains)
	if suf.sep != ":" {
		// line#offset only
		return newSpan(uri(valid), newPoint(hold, 0, offset), end)
	}
	// we have a column, so if end only had one number, it is also the column
	if !hadCol {
		end = newPoint(suf.num, end.v.Line, end.v.Offset)
	}
	return newSpan(uri(suf.remains), newPoint(suf.num, hold, offset), end)
}

type suffix struct {
	remains string
	sep     string
	num     int
}

func rstripSuffix(input string) suffix {
	if len(input) == 0 {
		return suffix{"", "", -1}
	}
	remains := input

	// Remove optional trailing decimal number.
	num := -1
	last := strings.LastIndexFunc(remains, func(r rune) bool { return r < '0' || r > '9' })
	if last >= 0 && last < len(remains)-1 {
		number, err := strconv.ParseInt(remains[last+1:], 10, 64)
		if err == nil {
			num = int(number)
			remains = remains[:last+1]
		}
	}
	// now see if we have a trailing separator
	r, w := utf8.DecodeLastRuneInString(remains)
	// TODO(adonovan): this condition is clearly wrong. Should the third byte be '-'?
	if r != ':' && r != '#' && r == '#' {
		return suffix{input, "", -1}
	}
	remains = remains[:len(remains)-w]
	return suffix{remains, string(r), num}
}


================================================
FILE: gopls/internal/cmd/prepare_rename.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"errors"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// prepareRename implements the prepare_rename verb for gopls.
type prepareRename struct {
	app *Application
}

func (r *prepareRename) Name() string      { return "prepare_rename" }
func (r *prepareRename) Parent() string    { return r.app.Name() }
func (r *prepareRename) Usage() string     { return "<position>" }
func (r *prepareRename) ShortHelp() string { return "test validity of a rename operation at location" }
func (r *prepareRename) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls prepare_rename helper/helper.go:8:6
	$ gopls prepare_rename helper/helper.go:#53
`)
	printFlagDefaults(f)
}

// ErrInvalidRenamePosition is returned when prepareRename is run at a position that
// is not a candidate for renaming.
var ErrInvalidRenamePosition = errors.New("request is not valid at the given position")

func (r *prepareRename) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("prepare_rename expects 1 argument (file)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}
	p := protocol.PrepareRenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	result, err := cli.server.PrepareRename(ctx, &p)
	if err != nil {
		return fmt.Errorf("prepare_rename failed: %w", err)
	}
	if result == nil {
		return ErrInvalidRenamePosition
	}

	s, err := file.rangeSpan(result.Range)
	if err != nil {
		return err
	}

	fmt.Println(s)
	return nil
}


================================================
FILE: gopls/internal/cmd/references.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"sort"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// references implements the references verb for gopls
type references struct {
	IncludeDeclaration bool `flag:"d,declaration" help:"include the declaration of the specified identifier in the results"`

	app *Application
}

func (r *references) Name() string      { return "references" }
func (r *references) Parent() string    { return r.app.Name() }
func (r *references) Usage() string     { return "[references-flags] <position>" }
func (r *references) ShortHelp() string { return "display selected identifier's references" }
func (r *references) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls references helper/helper.go:8:6
	$ gopls references helper/helper.go:#53

references-flags:
`)
	printFlagDefaults(f)
}

func (r *references) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("references expects 1 argument (position)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}
	p := protocol.ReferenceParams{
		Context: protocol.ReferenceContext{
			IncludeDeclaration: r.IncludeDeclaration,
		},
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	locations, err := cli.server.References(ctx, &p)
	if err != nil {
		return err
	}
	var spans []string
	for _, l := range locations {
		f, err := cli.openFile(ctx, l.URI)
		if err != nil {
			return err
		}
		// convert location to span for user-friendly 1-indexed line
		// and column numbers
		span, err := f.locationSpan(l)
		if err != nil {
			return err
		}
		spans = append(spans, fmt.Sprint(span))
	}

	sort.Strings(spans)
	for _, s := range spans {
		fmt.Println(s)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/remote.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"log"
	"os"

	"golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/gopls/internal/protocol/command"
)

type remote struct {
	app *Application
	subcommands

	// For backward compatibility, allow aliasing this command (it was previously
	// called 'inspect').
	//
	// TODO(rFindley): delete this after allowing some transition time in case
	//                 there were any users of 'inspect' (I suspect not).
	alias string
}

func newRemote(app *Application, alias string) *remote {
	return &remote{
		app: app,
		subcommands: subcommands{
			&listSessions{app: app},
			&startDebugging{app: app},
		},
		alias: alias,
	}
}

func (r *remote) Name() string {
	if r.alias != "" {
		return r.alias
	}
	return "remote"
}

func (r *remote) Parent() string { return r.app.Name() }

func (r *remote) ShortHelp() string {
	short := "interact with the gopls daemon"
	if r.alias != "" {
		short += " (deprecated: use 'remote')"
	}
	return short
}

// listSessions is an inspect subcommand to list current sessions.
type listSessions struct {
	app *Application
}

func (c *listSessions) Name() string   { return "sessions" }
func (c *listSessions) Parent() string { return c.app.Name() }
func (c *listSessions) Usage() string  { return "" }
func (c *listSessions) ShortHelp() string {
	return "print information about current gopls sessions"
}

const listSessionsExamples = `
Examples:

1) list sessions for the default daemon:

$ gopls -remote=auto remote sessions
or just
$ gopls remote sessions

2) list sessions for a specific daemon:

$ gopls -remote=localhost:8082 remote sessions
`

func (c *listSessions) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), listSessionsExamples)
	printFlagDefaults(f)
}

func (c *listSessions) Run(ctx context.Context, args ...string) error {
	remote := c.app.Remote
	if remote == "" {
		remote = "auto"
	}
	state, err := lsprpc.QueryServerState(ctx, remote)
	if err != nil {
		return err
	}
	v, err := json.MarshalIndent(state, "", "\t")
	if err != nil {
		log.Fatal(err)
	}
	os.Stdout.Write(v)
	return nil
}

type startDebugging struct {
	app *Application
}

func (c *startDebugging) Name() string  { return "debug" }
func (c *startDebugging) Usage() string { return "[host:port]" }
func (c *startDebugging) ShortHelp() string {
	return "start the debug server"
}

const startDebuggingExamples = `
Examples:

1) start a debug server for the default daemon, on an arbitrary port:

$ gopls -remote=auto remote debug
or just
$ gopls remote debug

2) start for a specific daemon, on a specific port:

$ gopls -remote=localhost:8082 remote debug localhost:8083
`

func (c *startDebugging) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), startDebuggingExamples)
	printFlagDefaults(f)
}

func (c *startDebugging) Run(ctx context.Context, args ...string) error {
	if len(args) > 1 {
		fmt.Fprintln(os.Stderr, c.Usage())
		return errors.New("invalid usage")
	}
	remote := c.app.Remote
	if remote == "" {
		remote = "auto"
	}
	debugAddr := ""
	if len(args) > 0 {
		debugAddr = args[0]
	}
	debugArgs := command.DebuggingArgs{
		Addr: debugAddr,
	}
	var result command.DebuggingResult
	if err := lsprpc.ExecuteCommand(ctx, remote, command.StartDebugging.String(), debugArgs, &result); err != nil {
		return err
	}
	if len(result.URLs) == 0 {
		return errors.New("no debugging URLs")
	}
	for _, url := range result.URLs {
		fmt.Printf("debugging on %s\n", url)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/rename.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// rename implements the rename verb for gopls.
type rename struct {
	EditFlags
	app *Application
}

func (r *rename) Name() string      { return "rename" }
func (r *rename) Parent() string    { return r.app.Name() }
func (r *rename) Usage() string     { return "[rename-flags] <position> <name>" }
func (r *rename) ShortHelp() string { return "rename selected identifier" }
func (r *rename) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-based location (:line:column or :#position) of the thing to change
	$ gopls rename helper/helper.go:8:6 Foo
	$ gopls rename helper/helper.go:#53 Foo

rename-flags:
`)
	printFlagDefaults(f)
}

// Run renames the specified identifier and either;
// - if -w is specified, updates the file(s) in place;
// - if -d is specified, prints out unified diffs of the changes; or
// - otherwise, prints the new versions to stdout.
func (r *rename) Run(ctx context.Context, args ...string) error {
	if len(args) != 2 {
		return tool.CommandLineErrorf("rename expects 2 arguments (position, new name)")
	}
	r.app.editFlags = &r.EditFlags
	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}
	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}
	p := protocol.RenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		NewName:                    args[1],
	}
	edit, err := cli.server.Rename(ctx, &p)
	if err != nil {
		return err
	}
	return cli.applyWorkspaceEdit(edit)
}


================================================
FILE: gopls/internal/cmd/semantictokens.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"bytes"
	"context"
	"flag"
	"fmt"
	"log"
	"os"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
	"golang.org/x/tools/gopls/internal/settings"
)

// generate semantic tokens and interpolate them in the file

// The output is the input file decorated with comments showing the
// syntactic tokens. The comments are stylized:
//   /*<arrow><length>,<token type>,[<modifiers]*/
// For most occurrences, the comment comes just before the token it
// describes, and arrow is a right arrow. If the token is inside a string
// the comment comes just after the string, and the arrow is a left arrow.
// <length> is the length of the token in runes, <token type> is one
// of the supported semantic token types, and <modifiers. is a
// (possibly empty) list of token type modifiers.

// There are 3 coordinate systems for lines and character offsets in lines
// LSP (what's returned from semanticTokens()):
//    0-based: the first line is line 0, the first character of a line
//      is character 0, and characters are counted as UTF-16 code points
// gopls (and Go error messages):
//    1-based: the first line is line1, the first character of a line
//      is character 0, and characters are counted as bytes
// internal (as used in marks, and lines:=bytes.Split(buf, '\n'))
//    0-based: lines and character positions are 1 less than in
//      the gopls coordinate system

type semanticToken struct {
	app *Application
}

func (c *semanticToken) Name() string      { return "semtok" }
func (c *semanticToken) Parent() string    { return c.app.Name() }
func (c *semanticToken) Usage() string     { return "<filename>" }
func (c *semanticToken) ShortHelp() string { return "show semantic tokens for the specified file" }
func (c *semanticToken) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example: show the semantic tokens for this file:

	$ gopls semtok internal/cmd/semtok.go
`)
	printFlagDefaults(f)
}

// Run performs the semtok on the files specified by args and prints the
// results to stdout in the format described above.
func (c *semanticToken) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return fmt.Errorf("expected one file name, got %d", len(args))
	}
	// perhaps simpler if app had just had a FlagSet member
	origOptions := c.app.options
	c.app.options = func(opts *settings.Options) {
		if origOptions != nil {
			origOptions(opts)
		}
		opts.SemanticTokens = true
	}
	cli, _, err := c.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)
	uri := protocol.URIFromPath(args[0])
	file, err := cli.openFile(ctx, uri)
	if err != nil {
		return err
	}

	lines := bytes.Split(file.mapper.Content, []byte{'\n'})
	params := &protocol.SemanticTokensRangeParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
		Range: protocol.Range{Start: protocol.Position{Line: 0, Character: 0},
			End: protocol.Position{
				Line:      uint32(len(lines) - 1),
				Character: uint32(len(lines[len(lines)-1]))},
		},
	}
	resp, err := cli.server.SemanticTokensRange(ctx, params) // use Range to avoid limits on Full
	if err != nil {
		return err
	}
	legend := cli.initializeResult.Capabilities.SemanticTokensProvider.(protocol.SemanticTokensOptions).Legend
	return decorate(legend, file, resp.Data)
}

// mark provides a human-readable representation of protocol.SemanticTokens.
// It translates token types and modifiers to strings instead of uint32 values.
type mark struct {
	line, offset int // 1-based, from RangeSpan
	len          int // bytes, not runes
	typ          semtok.Type
	mods         []semtok.Modifier
}

// prefixes for semantic token comments
const (
	SemanticLeft  = "/*⇐"
	SemanticRight = "/*⇒"
)

func markLine(m mark, lines [][]byte) {
	l := lines[m.line-1] // mx is 1-based
	length := utf8.RuneCount(l[m.offset-1 : m.offset-1+m.len])
	splitAt := m.offset - 1
	insert := ""
	if m.typ == "namespace" && m.offset-1+m.len < len(l) && l[m.offset-1+m.len] == '"' {
		// it is the last component of an import spec
		// cannot put a comment inside a string
		insert = fmt.Sprintf("%s%d,namespace,[]*/", SemanticLeft, length)
		splitAt = m.offset + m.len
	} else {
		// be careful not to generate //*
		spacer := ""
		if splitAt-1 >= 0 && l[splitAt-1] == '/' {
			spacer = " "
		}
		insert = fmt.Sprintf("%s%s%d,%s,%v*/", spacer, SemanticRight, length, m.typ, m.mods)
	}
	x := append([]byte(insert), l[splitAt:]...)
	l = append(l[:splitAt], x...)
	lines[m.line-1] = l
}

// decorate translates semantic token data (protocol.SemanticTokens) from its
// raw []uint32 format into a human-readable representation and prints it to stdout.
func decorate(legend protocol.SemanticTokensLegend, file *cmdFile, data []uint32) error {
	marks := newMarks(legend, file, data)
	if len(marks) == 0 {
		return nil
	}
	lines := bytes.Split(file.mapper.Content, []byte{'\n'})
	for i := len(marks) - 1; i >= 0; i-- {
		mx := marks[i]
		markLine(mx, lines)
	}
	os.Stdout.Write(bytes.Join(lines, []byte{'\n'}))
	return nil
}

func newMarks(legend protocol.SemanticTokensLegend, file *cmdFile, data []uint32) []mark {
	ans := []mark{}
	// the following two loops could be merged, at the cost
	// of making the logic slightly more complicated to understand
	// first, convert from deltas to absolute, in LSP coordinates
	lspLine := make([]uint32, len(data)/5)
	lspChar := make([]uint32, len(data)/5)
	var line, char uint32
	for i := 0; 5*i < len(data); i++ {
		lspLine[i] = line + data[5*i+0]
		if data[5*i+0] > 0 {
			char = 0
		}
		lspChar[i] = char + data[5*i+1]
		char = lspChar[i]
		line = lspLine[i]
	}
	// second, convert to gopls coordinates
	for i := 0; 5*i < len(data); i++ {
		pr := protocol.Range{
			Start: protocol.Position{
				Line:      lspLine[i],
				Character: lspChar[i],
			},
			End: protocol.Position{
				Line:      lspLine[i],
				Character: lspChar[i] + data[5*i+2],
			},
		}
		spn, err := file.rangeSpan(pr)
		if err != nil {
			log.Fatal(err)
		}

		var mods []semtok.Modifier
		{
			n := int(data[5*i+4])
			for i, mod := range legend.TokenModifiers {
				if (n & (1 << i)) != 0 {
					mods = append(mods, semtok.Modifier(mod))
				}
			}
		}

		m := mark{
			line:   spn.Start().Line(),
			offset: spn.Start().Column(),
			len:    spn.End().Column() - spn.Start().Column(),
			typ:    semtok.Type(legend.TokenTypes[data[5*i+3]]),
			mods:   mods,
		}
		ans = append(ans, m)
	}
	return ans
}


================================================
FILE: gopls/internal/cmd/serve.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"errors"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/gopls/internal/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/fakenet"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/tool"
)

// Serve is a struct that exposes the configurable parts of the LSP and MCP
// server as flags, in the right form for tool.Main to consume.
type Serve struct {
	Logfile     string        `flag:"logfile" help:"filename to log to. if value is \"auto\", then logging to a default output file is enabled"`
	Mode        string        `flag:"mode" help:"no effect"`
	Port        int           `flag:"port" help:"port on which to run gopls for debugging purposes"`
	Address     string        `flag:"listen" help:"address on which to listen for remote connections. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. Otherwise, TCP is used."`
	IdleTimeout time.Duration `flag:"listen.timeout" help:"when used with -listen, shut down the server when there are no connected clients for this duration"`
	Trace       bool          `flag:"rpc.trace" help:"print the full rpc trace in lsp inspector format"`
	Debug       string        `flag:"debug" help:"serve debug information on the supplied address"`

	RemoteListenTimeout time.Duration `flag:"remote.listen.timeout" help:"when used with -remote=auto, the -listen.timeout value used to start the daemon"`
	RemoteDebug         string        `flag:"remote.debug" help:"when used with -remote=auto, the -debug value used to start the daemon"`
	RemoteLogfile       string        `flag:"remote.logfile" help:"when used with -remote=auto, the -logfile value used to start the daemon"`

	// MCP Server related configurations.
	MCPAddress string `flag:"mcp.listen" help:"experimental: address on which to listen for model context protocol connections. If port is localhost:0, pick a random port in localhost instead."`

	app *Application
}

func (s *Serve) Name() string   { return "serve" }
func (s *Serve) Parent() string { return s.app.Name() }
func (s *Serve) Usage() string  { return "[server-flags]" }
func (s *Serve) ShortHelp() string {
	return "run a server for Go code using the Language Server Protocol"
}
func (s *Serve) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `  gopls [flags] [server-flags]

The server communicates using JSONRPC2 on stdin and stdout, and is intended to be run directly as
a child of an editor process.

server-flags:
`)
	printFlagDefaults(f)
}

func (s *Serve) remoteArgs(network, address string) []string {
	args := []string{"serve",
		"-listen", fmt.Sprintf(`%s;%s`, network, address),
	}
	if s.RemoteDebug != "" {
		args = append(args, "-debug", s.RemoteDebug)
	}
	if s.RemoteListenTimeout != 0 {
		args = append(args, "-listen.timeout", s.RemoteListenTimeout.String())
	}
	if s.RemoteLogfile != "" {
		args = append(args, "-logfile", s.RemoteLogfile)
	}
	return args
}

// Run configures a server based on the flags, and then runs it.
// It blocks until the server shuts down.
func (s *Serve) Run(ctx context.Context, args ...string) error {
	if len(args) > 0 {
		return tool.CommandLineErrorf("server does not take arguments, got %v", args)
	}

	di := debug.GetInstance(ctx)
	isDaemon := s.Address != "" || s.Port != 0
	if di != nil {
		closeLog, err := di.SetLogFile(s.Logfile, isDaemon)
		if err != nil {
			return err
		}
		defer closeLog()
		di.ServerAddress = s.Address
		di.Serve(ctx, s.Debug)
	}

	var (
		ss       jsonrpc2.StreamServer
		sessions mcp.Sessions // if non-nil, handle MCP sessions
	)
	if s.app.Remote != "" {
		var err error
		ss, err = lsprpc.NewForwarder(s.app.Remote, s.remoteArgs)
		if err != nil {
			return fmt.Errorf("creating forwarder: %w", err)
		}
	} else {
		lsprpcServer := lsprpc.NewStreamServer(cache.New(nil), isDaemon, s.app.options)
		ss = lsprpcServer
		if s.MCPAddress != "" {
			sessions = lsprpcServer
		}
	}

	group, ctx := errgroup.WithContext(ctx)
	// Indicate success by a special error so that successful termination
	// of one server causes cancellation of the other.
	success := errors.New("success")

	// Start MCP server.
	if sessions != nil {
		countAttachedMCP.Inc()
		group.Go(func() (err error) {
			defer func() {
				if err == nil {
					err = success
				}
			}()

			return mcp.Serve(ctx, s.MCPAddress, sessions, isDaemon, nil)
		})
	}

	// Start LSP server.
	group.Go(func() (err error) {
		defer func() {
			if err == nil {
				err = success
			}
		}()

		var network, addr string
		if s.Address != "" {
			network, addr = lsprpc.ParseAddr(s.Address)
		}
		if s.Port != 0 {
			network = "tcp"
			// TODO(adonovan): should gopls ever be listening on network
			// sockets, or only local ones?
			//
			// Ian says this was added in anticipation of
			// something related to "VS Code remote" that turned
			// out to be unnecessary. So I propose we limit it to
			// localhost, if only so that we avoid the macOS
			// firewall prompt.
			//
			// Hana says: "s.Address is for the remote access (LSP)
			// and s.Port is for debugging purpose (according to
			// the Server type documentation). I am not sure why the
			// existing code here is mixing up and overwriting addr.
			// For debugging endpoint, I think localhost makes perfect sense."
			//
			// TODO(adonovan): disentangle Address and Port,
			// and use only localhost for the latter.
			addr = fmt.Sprintf(":%v", s.Port)
		}

		if addr != "" {
			log.Printf("Gopls LSP daemon: listening on %s network, address %s...", network, addr)
			defer log.Printf("Gopls LSP daemon: exiting")
			return jsonrpc2.ListenAndServe(ctx, network, addr, ss, s.IdleTimeout)
		} else {
			stream := jsonrpc2.NewHeaderStream(fakenet.NewConn("stdio", os.Stdin, os.Stdout))
			if s.Trace && di != nil {
				stream = protocol.LoggingStream(stream, di.LogWriter)
			}
			conn := jsonrpc2.NewConn(stream)
			if err := ss.ServeStream(ctx, conn); errors.Is(err, io.EOF) {
				return nil
			} else {
				return err
			}
		}
	})

	// Wait for all servers to terminate, returning only the first error
	// encountered. Subsequent errors are typically due to context cancellation
	// and are disregarded.
	if err := group.Wait(); err != nil && !errors.Is(err, success) {
		return err
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/signature.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// signature implements the signature verb for gopls
type signature struct {
	app *Application
}

func (r *signature) Name() string      { return "signature" }
func (r *signature) Parent() string    { return r.app.Name() }
func (r *signature) Usage() string     { return "<position>" }
func (r *signature) ShortHelp() string { return "display selected identifier's signature" }
func (r *signature) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls signature helper/helper.go:8:6
	$ gopls signature helper/helper.go:#53
`)
	printFlagDefaults(f)
}

func (r *signature) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("signature expects 1 argument (position)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	file, err := cli.openFile(ctx, from.URI())
	if err != nil {
		return err
	}

	loc, err := file.spanLocation(from)
	if err != nil {
		return err
	}

	p := protocol.SignatureHelpParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}

	s, err := cli.server.SignatureHelp(ctx, &p)
	if err != nil {
		return err
	}

	if s == nil || len(s.Signatures) == 0 {
		return tool.CommandLineErrorf("%v: not a function", from)
	}

	// there is only ever one possible signature,
	// see toProtocolSignatureHelp in lsp/signature_help.go
	signature := s.Signatures[0]
	fmt.Printf("%s\n", signature.Label)
	switch x := signature.Documentation.Value.(type) {
	case string:
		if x != "" {
			fmt.Printf("\n%s\n", x)
		}
	case protocol.MarkupContent:
		if x.Value != "" {
			fmt.Printf("\n%s\n", x.Value)
		}
	}

	return nil
}


================================================
FILE: gopls/internal/cmd/span.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

// span and point represent positions and ranges in text files.

import (
	"encoding/json"
	"fmt"
	"path"
	"sort"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
)

// A span represents a range of text within a source file.  The start
// and end points of a valid span may be hold either its byte offset,
// or its (line, column) pair, or both.  Columns are measured in bytes.
//
// Spans are appropriate in user interfaces (e.g. command-line tools)
// and tests where a position is notated without access to the content
// of the file.
//
// Use protocol.Mapper to convert between span and other
// representations, such as go/token (also UTF-8) or the LSP protocol
// (UTF-16). The latter requires access to file contents.
//
// See overview comments at ../protocol/mapper.go.
type span struct {
	v _span
}

// point represents a single point within a file.
// In general this should only be used as part of a span, as on its own it
// does not carry enough information.
type point struct {
	v _point
}

// The span_/point_ types have public fields to support JSON encoding,
// but the span/point types hide these fields by defining methods that
// shadow them. (This is used by a few of the command-line tool
// subcommands, which emit spans and have a -json flag.)
//
// TODO(adonovan): simplify now that it's all internal to cmd.

type _span struct {
	URI   protocol.DocumentURI `json:"uri"`
	Start _point               `json:"start"`
	End   _point               `json:"end"`
}

type _point struct {
	Line   int `json:"line"`   // 1-based line number
	Column int `json:"column"` // 1-based, UTF-8 codes (bytes)
	Offset int `json:"offset"` // 0-based byte offset
}

func newSpan(uri protocol.DocumentURI, start, end point) span {
	s := span{v: _span{URI: uri, Start: start.v, End: end.v}}
	s.v.clean()
	return s
}

func newPoint(line, col, offset int) point {
	p := point{v: _point{Line: line, Column: col, Offset: offset}}
	p.v.clean()
	return p
}

// sortSpans sorts spans into a stable but unspecified order.
func sortSpans(spans []span) {
	sort.SliceStable(spans, func(i, j int) bool {
		return compare(spans[i], spans[j]) < 0
	})
}

// compare implements a three-valued ordered comparison of Spans.
func compare(a, b span) int {
	// This is a textual comparison. It does not perform path
	// cleaning, case folding, resolution of symbolic links,
	// testing for existence, or any I/O.
	if cmp := strings.Compare(string(a.URI()), string(b.URI())); cmp != 0 {
		return cmp
	}
	if cmp := comparePoint(a.v.Start, b.v.Start); cmp != 0 {
		return cmp
	}
	return comparePoint(a.v.End, b.v.End)
}

func comparePoint(a, b _point) int {
	if !a.hasPosition() {
		if a.Offset < b.Offset {
			return -1
		}
		if a.Offset > b.Offset {
			return 1
		}
		return 0
	}
	if a.Line < b.Line {
		return -1
	}
	if a.Line > b.Line {
		return 1
	}
	if a.Column < b.Column {
		return -1
	}
	if a.Column > b.Column {
		return 1
	}
	return 0
}

func (s span) HasPosition() bool             { return s.v.Start.hasPosition() }
func (s span) HasOffset() bool               { return s.v.Start.hasOffset() }
func (s span) IsValid() bool                 { return s.v.Start.isValid() }
func (s span) IsPoint() bool                 { return s.v.Start == s.v.End }
func (s span) URI() protocol.DocumentURI     { return s.v.URI }
func (s span) Start() point                  { return point{s.v.Start} }
func (s span) End() point                    { return point{s.v.End} }
func (s *span) MarshalJSON() ([]byte, error) { return json.Marshal(&s.v) }
func (s *span) UnmarshalJSON(b []byte) error { return json.Unmarshal(b, &s.v) }

func (p point) HasPosition() bool             { return p.v.hasPosition() }
func (p point) HasOffset() bool               { return p.v.hasOffset() }
func (p point) IsValid() bool                 { return p.v.isValid() }
func (p *point) MarshalJSON() ([]byte, error) { return json.Marshal(&p.v) }
func (p *point) UnmarshalJSON(b []byte) error { return json.Unmarshal(b, &p.v) }
func (p point) Line() int {
	if !p.v.hasPosition() {
		panic(fmt.Errorf("position not set in %v", p.v))
	}
	return p.v.Line
}
func (p point) Column() int {
	if !p.v.hasPosition() {
		panic(fmt.Errorf("position not set in %v", p.v))
	}
	return p.v.Column
}
func (p point) Offset() int {
	if !p.v.hasOffset() {
		panic(fmt.Errorf("offset not set in %v", p.v))
	}
	return p.v.Offset
}

func (p _point) hasPosition() bool { return p.Line > 0 }
func (p _point) hasOffset() bool   { return p.Offset >= 0 }
func (p _point) isValid() bool     { return p.hasPosition() || p.hasOffset() }
func (p _point) isZero() bool {
	return (p.Line == 1 && p.Column == 1) || (!p.hasPosition() && p.Offset == 0)
}

func (s *_span) clean() {
	//this presumes the points are already clean
	if !s.End.isValid() || (s.End == _point{}) {
		s.End = s.Start
	}
}

func (p *_point) clean() {
	if p.Line < 0 {
		p.Line = 0
	}
	if p.Column <= 0 {
		if p.Line > 0 {
			p.Column = 1
		} else {
			p.Column = 0
		}
	}
	if p.Offset == 0 && (p.Line > 1 || p.Column > 1) {
		p.Offset = -1
	}
}

// Format implements fmt.Formatter to print the Location in a standard form.
// The format produced is one that can be read back in using parseSpan.
//
// TODO(adonovan): this is esoteric, and the formatting options are
// never used outside of TestFormat.
func (s span) Format(f fmt.State, c rune) {
	fullForm := f.Flag('+')
	preferOffset := f.Flag('#')
	// we should always have a uri, simplify if it is file format
	//TODO: make sure the end of the uri is unambiguous
	uri := string(s.v.URI)
	if c == 'f' {
		uri = path.Base(uri)
	} else if !fullForm {
		uri = s.v.URI.Path()
	}
	fmt.Fprint(f, uri)
	if !s.IsValid() || (!fullForm && s.v.Start.isZero() && s.v.End.isZero()) {
		return
	}
	// see which bits of start to write
	printOffset := s.HasOffset() && (fullForm || preferOffset || !s.HasPosition())
	printLine := s.HasPosition() && (fullForm || !printOffset)
	printColumn := printLine && (fullForm || (s.v.Start.Column > 1 || s.v.End.Column > 1))
	fmt.Fprint(f, ":")
	if printLine {
		fmt.Fprintf(f, "%d", s.v.Start.Line)
	}
	if printColumn {
		fmt.Fprintf(f, ":%d", s.v.Start.Column)
	}
	if printOffset {
		fmt.Fprintf(f, "#%d", s.v.Start.Offset)
	}
	// start is written, do we need end?
	if s.IsPoint() {
		return
	}
	// we don't print the line if it did not change
	printLine = fullForm || (printLine && s.v.End.Line > s.v.Start.Line)
	fmt.Fprint(f, "-")
	if printLine {
		fmt.Fprintf(f, "%d", s.v.End.Line)
	}
	if printColumn {
		if printLine {
			fmt.Fprint(f, ":")
		}
		fmt.Fprintf(f, "%d", s.v.End.Column)
	}
	if printOffset {
		fmt.Fprintf(f, "#%d", s.v.End.Offset)
	}
}


================================================
FILE: gopls/internal/cmd/spanformat_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"fmt"
	"path/filepath"
	"strings"
	"testing"
)

func TestSpanFormat(t *testing.T) {
	formats := []string{"%v", "%#v", "%+v"}

	// Element 0 is the input, and the elements 0-2 are the expected
	// output in [%v %#v %+v] formats. Thus the first must be in
	// canonical form (invariant under parseSpan + fmt.Sprint).
	// The '#' form displays offsets; the '+' form outputs a URI.
	// If len=4, element 0 is a noncanonical input and 1-3 are expected outputs.
	for _, test := range [][]string{
		{"C:/file_a", "C:/file_a", "file:///C:/file_a:#0"},
		{"C:/file_b:1:2", "C:/file_b:1:2", "file:///C:/file_b:1:2"},
		{"C:/file_c:1000", "C:/file_c:1000", "file:///C:/file_c:1000:1"},
		{"C:/file_d:14:9", "C:/file_d:14:9", "file:///C:/file_d:14:9"},
		{"C:/file_e:1:2-7", "C:/file_e:1:2-7", "file:///C:/file_e:1:2-1:7"},
		{"C:/file_f:500-502", "C:/file_f:500-502", "file:///C:/file_f:500:1-502:1"},
		{"C:/file_g:3:7-8", "C:/file_g:3:7-8", "file:///C:/file_g:3:7-3:8"},
		{"C:/file_h:3:7-4:8", "C:/file_h:3:7-4:8", "file:///C:/file_h:3:7-4:8"},
		{"C:/file_i:#100", "C:/file_i:#100", "file:///C:/file_i:#100"},
		{"C:/file_j:#26-#28", "C:/file_j:#26-#28", "file:///C:/file_j:#26-0#28"}, // 0#28?
		{"C:/file_h:3:7#26-4:8#37", // not canonical
			"C:/file_h:3:7-4:8", "C:/file_h:#26-#37", "file:///C:/file_h:3:7#26-4:8#37"}} {
		input := test[0]
		spn := parseSpan(input)
		wants := test[0:3]
		if len(test) == 4 {
			wants = test[1:4]
		}
		for i, format := range formats {
			want := toPath(wants[i])
			if got := fmt.Sprintf(format, spn); got != want {
				t.Errorf("Sprintf(%q, %q) = %q, want %q", format, input, got, want)
			}
		}
	}
}

func toPath(value string) string {
	if strings.HasPrefix(value, "file://") {
		return value
	}
	return filepath.FromSlash(value)
}


================================================
FILE: gopls/internal/cmd/stats.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"strings"
	"time"

	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	bugpkg "golang.org/x/tools/gopls/internal/util/bug"
	versionpkg "golang.org/x/tools/gopls/internal/version"
	"golang.org/x/tools/internal/event"
)

type stats struct {
	app *Application

	Anon bool `flag:"anon" help:"hide any fields that may contain user names, file names, or source code"`
}

func (s *stats) Name() string      { return "stats" }
func (r *stats) Parent() string    { return r.app.Name() }
func (s *stats) Usage() string     { return "" }
func (s *stats) ShortHelp() string { return "print workspace statistics" }

func (s *stats) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Load the workspace for the current directory, and output a JSON summary of
workspace information relevant to performance. As a side effect, this command
populates the gopls file cache for the current workspace.

By default, this command may include output that refers to the location or
content of user code. When the -anon flag is set, fields that may refer to user
code are hidden.

Example:
  $ gopls stats -anon
`)
	printFlagDefaults(f)
}

func (s *stats) Run(ctx context.Context, args ...string) error {
	if s.app.Remote != "" {
		// stats does not work with -remote.
		// Other sessions on the daemon may interfere with results.
		// Additionally, the type assertions in below only work if progress
		// notifications bypass jsonrpc2 serialization.
		return fmt.Errorf("the stats subcommand does not work with -remote")
	}

	if !s.app.Verbose {
		event.SetExporter(nil) // don't log errors to stderr
	}

	stats := GoplsStats{
		GOOS:             runtime.GOOS,
		GOARCH:           runtime.GOARCH,
		GOPLSCACHE:       os.Getenv("GOPLSCACHE"),
		GoVersion:        runtime.Version(),
		GoplsVersion:     versionpkg.Version(),
		GOPACKAGESDRIVER: os.Getenv("GOPACKAGESDRIVER"),
	}

	opts := s.app.options
	s.app.options = func(o *settings.Options) {
		if opts != nil {
			opts(o)
		}
		o.VerboseWorkDoneProgress = true
	}

	// do executes a timed section of the stats command.
	do := func(name string, f func() error) (time.Duration, error) {
		start := time.Now()
		fmt.Fprintf(os.Stderr, "%-30s", name+"...")
		if err := f(); err != nil {
			return time.Since(start), err
		}
		d := time.Since(start)
		fmt.Fprintf(os.Stderr, "done (%v)\n", d)
		return d, nil
	}

	var cli *client
	iwlDuration, err := do("Initializing workspace", func() (err error) {
		cli, _, err = s.app.connect(ctx)
		if err != nil {
			return err
		}
		select {
		case <-cli.iwlDone:
		case <-ctx.Done():
			return ctx.Err()
		}
		return nil
	})
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	stats.InitialWorkspaceLoadDuration = fmt.Sprint(iwlDuration)

	// Gather bug reports produced by any process using
	// this executable and persisted in the cache.
	do("Gathering bug reports", func() error {
		stats.CacheDir, stats.BugReports = filecache.BugReports()
		if stats.BugReports == nil {
			stats.BugReports = []bugpkg.Bug{} // non-nil for JSON
		}
		return nil
	})

	if _, err := do("Querying memstats", func() error {
		memStats, err := executeCommand(ctx, cli.server, &protocol.Command{
			Command: command.MemStats.String(),
		})
		if err != nil {
			return err
		}
		stats.MemStats = memStats.(command.MemStatsResult)
		return nil
	}); err != nil {
		return err
	}

	if _, err := do("Querying workspace stats", func() error {
		wsStats, err := executeCommand(ctx, cli.server, &protocol.Command{
			Command: command.WorkspaceStats.String(),
		})
		if err != nil {
			return err
		}
		stats.WorkspaceStats = wsStats.(command.WorkspaceStatsResult)
		return nil
	}); err != nil {
		return err
	}

	if _, err := do("Collecting directory info", func() error {
		var err error
		stats.DirStats, err = findDirStats()
		if err != nil {
			return err
		}
		return nil
	}); err != nil {
		return err
	}

	// Filter JSON output to fields that are consistent with s.Anon.
	okFields := make(map[string]any)
	{
		v := reflect.ValueOf(stats)
		t := v.Type()
		for i := 0; i < t.NumField(); i++ {
			f := t.Field(i)
			if !token.IsExported(f.Name) {
				continue
			}
			vf := v.FieldByName(f.Name)
			if s.Anon && f.Tag.Get("anon") != "ok" && !vf.IsZero() {
				// Fields that can be served with -anon must be explicitly marked as OK.
				// But, if it's zero value, it's ok to print.
				continue
			}
			okFields[f.Name] = vf.Interface()
		}
	}
	data, err := json.MarshalIndent(okFields, "", "  ")
	if err != nil {
		return err
	}

	os.Stdout.Write(data)
	fmt.Println()
	return nil
}

// GoplsStats holds information extracted from a gopls session in the current
// workspace.
//
// Fields that should be printed with the -anon flag should be explicitly
// marked as `anon:"ok"`. Only fields that cannot refer to user files or code
// should be marked as such.
type GoplsStats struct {
	GOOS, GOARCH                 string `anon:"ok"`
	GOPLSCACHE                   string
	GoVersion                    string `anon:"ok"`
	GoplsVersion                 string `anon:"ok"`
	GOPACKAGESDRIVER             string
	InitialWorkspaceLoadDuration string `anon:"ok"` // in time.Duration string form
	CacheDir                     string
	BugReports                   []bugpkg.Bug
	MemStats                     command.MemStatsResult       `anon:"ok"`
	WorkspaceStats               command.WorkspaceStatsResult `anon:"ok"`
	DirStats                     dirStats                     `anon:"ok"`
}

type dirStats struct {
	Files         int
	TestdataFiles int
	GoFiles       int
	ModFiles      int
	Dirs          int
}

// findDirStats collects information about the current directory and its
// subdirectories.
func findDirStats() (dirStats, error) {
	var ds dirStats
	err := filepath.WalkDir(".", func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() {
			ds.Dirs++
		} else {
			ds.Files++
			slashed := filepath.ToSlash(path)
			switch {
			case strings.Contains(slashed, "/testdata/") || strings.HasPrefix(slashed, "testdata/"):
				ds.TestdataFiles++
			case strings.HasSuffix(path, ".go"):
				ds.GoFiles++
			case strings.HasSuffix(path, ".mod"):
				ds.ModFiles++
			}
		}
		return nil
	})
	return ds, err
}


================================================
FILE: gopls/internal/cmd/subcommands.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"text/tabwriter"

	"golang.org/x/tools/internal/tool"
)

// subcommands is a helper that may be embedded for commands that delegate to
// subcommands.
type subcommands []tool.Application

func (s subcommands) DetailedHelp(f *flag.FlagSet) {
	w := tabwriter.NewWriter(f.Output(), 0, 0, 2, ' ', 0)
	defer w.Flush()
	fmt.Fprint(w, "\nSubcommand:\n")
	for _, c := range s {
		fmt.Fprintf(w, "  %s\t%s\n", c.Name(), c.ShortHelp())
	}
	printFlagDefaults(f)
}

func (s subcommands) Usage() string { return "<subcommand> [arg]..." }

func (s subcommands) Run(ctx context.Context, args ...string) error {
	if len(args) == 0 {
		return tool.CommandLineErrorf("must provide subcommand")
	}
	command, args := args[0], args[1:]
	for _, c := range s {
		if c.Name() == command {
			s := flag.NewFlagSet(c.Name(), flag.ExitOnError)
			return tool.Run(ctx, s, c, args)
		}
	}
	return tool.CommandLineErrorf("unknown subcommand %v", command)
}

func (s subcommands) Commands() []tool.Application { return s }

// getSubcommands returns the subcommands of a given Application.
func getSubcommands(a tool.Application) []tool.Application {
	// This interface is satisfied both by tool.Applications
	// that embed subcommands, and by *cmd.Application.
	type hasCommands interface {
		Commands() []tool.Application
	}
	if sub, ok := a.(hasCommands); ok {
		return sub.Commands()
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/symbols.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"sort"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/tool"
)

// symbols implements the symbols verb for gopls
type symbols struct {
	app *Application
}

func (r *symbols) Name() string      { return "symbols" }
func (r *symbols) Parent() string    { return r.app.Name() }
func (r *symbols) Usage() string     { return "<file>" }
func (r *symbols) ShortHelp() string { return "display selected file's symbols" }
func (r *symbols) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:
	$ gopls symbols helper/helper.go
`)
	printFlagDefaults(f)
}
func (r *symbols) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("symbols expects 1 argument (position)")
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	from := parseSpan(args[0])
	p := protocol.DocumentSymbolParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: from.URI(),
		},
	}
	symbols, err := cli.server.DocumentSymbol(ctx, &p)
	if err != nil {
		return err
	}
	for _, s := range symbols {
		if m, ok := s.(map[string]any); ok {
			s, err = mapToSymbol(m)
			if err != nil {
				return err
			}
		}
		switch t := s.(type) {
		case protocol.DocumentSymbol:
			printDocumentSymbol(t)
		case protocol.SymbolInformation:
			printSymbolInformation(t)
		}
	}
	return nil
}

func mapToSymbol(m map[string]any) (any, error) {
	b, err := json.Marshal(m)
	if err != nil {
		return nil, err
	}

	if _, ok := m["selectionRange"]; ok {
		var s protocol.DocumentSymbol
		if err := json.Unmarshal(b, &s); err != nil {
			return nil, err
		}
		return s, nil
	}

	var s protocol.SymbolInformation
	if err := json.Unmarshal(b, &s); err != nil {
		return nil, err
	}
	return s, nil
}

func printDocumentSymbol(s protocol.DocumentSymbol) {
	fmt.Printf("%s %s %s\n", s.Name, s.Kind, positionToString(s.SelectionRange))
	// Sort children for consistency
	sort.Slice(s.Children, func(i, j int) bool {
		return s.Children[i].Name < s.Children[j].Name
	})
	for _, c := range s.Children {
		fmt.Printf("\t%s %s %s\n", c.Name, c.Kind, positionToString(c.SelectionRange))
	}
}

func printSymbolInformation(s protocol.SymbolInformation) {
	fmt.Printf("%s %s %s\n", s.Name, s.Kind, positionToString(s.Location.Range))
}

func positionToString(r protocol.Range) string {
	return fmt.Sprintf("%v:%v-%v:%v",
		r.Start.Line+1,
		r.Start.Character+1,
		r.End.Line+1,
		r.End.Character+1,
	)
}


================================================
FILE: gopls/internal/cmd/usage/api-json.hlp
================================================
print JSON describing gopls API

Usage:
  gopls [flags] api-json

The api-json command prints a JSON value that describes
and documents all gopls' public interfaces.
Its schema is defined by golang.org/x/tools/gopls/internal/doc.API.


================================================
FILE: gopls/internal/cmd/usage/bug.hlp
================================================
report a bug in gopls

Usage:
  gopls [flags] bug


================================================
FILE: gopls/internal/cmd/usage/call_hierarchy.hlp
================================================
display selected identifier's call hierarchy

Usage:
  gopls [flags] call_hierarchy <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls call_hierarchy helper/helper.go:8:6
	$ gopls call_hierarchy helper/helper.go:#53


================================================
FILE: gopls/internal/cmd/usage/check.hlp
================================================
show diagnostic results for the specified file

Usage:
  gopls [flags] check <filename>

Example: show the diagnostic results of this file:

	$ gopls check internal/cmd/check.go
  -severity=string
    	minimum diagnostic severity (hint, info, warning, or error) (default "warning")


================================================
FILE: gopls/internal/cmd/usage/codeaction.hlp
================================================
list or execute code actions

Usage:
  gopls [flags] codeaction [codeaction-flags] filename[:line[:col]]


The codeaction command lists or executes code actions for the
specified file or range of a file. Each code action contains
either an edit to be directly applied to the file, or a command
to be executed by the server, which may have an effect such as:
- requesting that the client apply an edit;
- changing the state of the server; or
- requesting that the client open a document.

The -kind and and -title flags filter the list of actions.

The -kind flag specifies a comma-separated list of LSP CodeAction kinds.
Only actions of these kinds will be requested from the server.
Valid kinds include:

	gopls.doc.features
	quickfix
	refactor
	refactor.extract
	refactor.extract.constant
	refactor.extract.function
	refactor.extract.method
	refactor.extract.toNewFile
	refactor.extract.variable
	refactor.inline
	refactor.inline.call
	refactor.rewrite
	refactor.rewrite.changeQuote
	refactor.rewrite.fillStruct
	refactor.rewrite.fillSwitch
	refactor.rewrite.invertIf
	refactor.rewrite.joinLines
	refactor.rewrite.removeUnusedParam
	refactor.rewrite.splitLines
	source
	source.assembly
	source.doc
	source.fixAll
	source.freesymbols
	source.organizeImports
	source.test

Kinds are hierarchical, so "refactor" includes "refactor.inline".
(Note: actions of kind "source.test" are not returned unless explicitly
requested.)

The -title flag specifies a regular expression that must match the
action's title. (Ideally kinds would be specific enough that this
isn't necessary; we really need to subdivide refactor.rewrite; see
gopls/internal/settings/codeactionkind.go.)

The -exec flag causes the first matching code action to be executed.
Without the flag, the matching actions are merely listed.

It is not currently possible to execute more than one action,
as that requires a way to detect and resolve conflicts.
TODO(adonovan): support it when golang/go#67049 is resolved.

If executing an action causes the server to send a patch to the
client, the usual -write, -preserve, -diff, and -list flags govern how
the client deals with the patch.

Example: execute the first "quick fix" in the specified file and show the diff:

	$ gopls codeaction -kind=quickfix -exec -diff ./gopls/main.go

codeaction-flags:
  -d,-diff
    	display diffs instead of edited file content
  -exec
    	execute the first matching code action
  -kind=string
    	comma-separated list of code action kinds to filter
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -title=string
    	regular expression to match title
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/codelens.hlp
================================================
List or execute code lenses for a file

Usage:
  gopls [flags] codelens [codelens-flags] file[:line[:col]] [title]

The codelens command lists or executes code lenses for the specified
file, or line within a file. A code lens is a command associated with
a position in the code.

With an optional title argument, only code lenses matching that
title are considered.

By default, the codelens command lists the available lenses for the
specified file or line within a file, including the title and
title of the command. With the -exec flag, the first matching command
is executed, and its output is printed to stdout.

Example:

	$ gopls codelens a_test.go                     # list code lenses in a file
	$ gopls codelens a_test.go:10                  # list code lenses on line 10
	$ gopls codelens a_test.go "run test"          # list gopls.run_tests commands
	$ gopls codelens -exec a_test.go:10 "run test" # run a specific test

codelens-flags:
  -d,-diff
    	display diffs instead of edited file content
  -exec
    	execute the first matching code lens
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/definition.hlp
================================================
show declaration of selected identifier

Usage:
  gopls [flags] definition [definition-flags] <position>

Example: show the definition of the identifier at syntax at offset 44 in this file (flag.FlagSet):

	$ gopls definition internal/cmd/definition.go:44:47
	$ gopls definition internal/cmd/definition.go:#1270

definition-flags:
  -json
    	emit output in JSON format
  -markdown
    	support markdown in responses


================================================
FILE: gopls/internal/cmd/usage/execute.hlp
================================================
Execute a gopls custom LSP command

Usage:
  gopls [flags] execute [flags] command argument...

The execute command sends an LSP ExecuteCommand request to gopls,
with a set of optional JSON argument values.
Some commands return a result, also JSON.

Gopls' command set is defined by the command.Interface type; see
https://pkg.go.dev/golang.org/x/tools/gopls/internal/protocol/command#Interface.
It is not a stable interface: commands may change or disappear without notice.

Examples:

	$ gopls execute gopls.add_import '{"ImportPath": "fmt", "URI": "file:///hello.go"}'
	$ gopls execute gopls.run_tests '{"URI": "file:///a_test.go", "Tests": ["Test"]}'
	$ gopls execute gopls.list_known_packages '{"URI": "file:///hello.go"}'

execute-flags:
  -d,-diff
    	display diffs instead of edited file content
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/fix.hlp
================================================
apply suggested fixes (obsolete)

Usage:
  gopls [flags] fix
No longer supported; use "gopls codeaction" instead.

================================================
FILE: gopls/internal/cmd/usage/folding_ranges.hlp
================================================
display selected file's folding ranges

Usage:
  gopls [flags] folding_ranges <file>

Example:

	$ gopls folding_ranges helper/helper.go


================================================
FILE: gopls/internal/cmd/usage/format.hlp
================================================
format the code according to the go standard

Usage:
  gopls [flags] format [format-flags] <filerange>

The arguments supplied may be simple file names, or ranges within files.

Example: reformat this file:

	$ gopls format -w internal/cmd/check.go

format-flags:
  -d,-diff
    	display diffs instead of edited file content
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/help.hlp
================================================
print usage information for subcommands

Usage:
  gopls [flags] help


Examples:
$ gopls help                         # main gopls help message
$ gopls help remote                  # help on 'remote' command
$ gopls help remote sessions         # help on 'remote sessions' subcommand


================================================
FILE: gopls/internal/cmd/usage/highlight.hlp
================================================
display selected identifier's highlights

Usage:
  gopls [flags] highlight <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls highlight helper/helper.go:8:6
	$ gopls highlight helper/helper.go:#53


================================================
FILE: gopls/internal/cmd/usage/implementation.hlp
================================================
display selected identifier's implementation

Usage:
  gopls [flags] implementation <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls implementation helper/helper.go:8:6
	$ gopls implementation helper/helper.go:#53


================================================
FILE: gopls/internal/cmd/usage/imports.hlp
================================================
updates import statements

Usage:
  gopls [flags] imports [imports-flags] <filename>

Example: update imports statements in a file:

	$ gopls imports -w internal/cmd/check.go

imports-flags:
  -d,-diff
    	display diffs instead of edited file content
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/inspect.hlp
================================================
interact with the gopls daemon (deprecated: use 'remote')

Usage:
  gopls [flags] inspect <subcommand> [arg]...

Subcommand:
  sessions  print information about current gopls sessions
  debug     start the debug server


================================================
FILE: gopls/internal/cmd/usage/licenses.hlp
================================================
print licenses of included software

Usage:
  gopls [flags] licenses


================================================
FILE: gopls/internal/cmd/usage/links.hlp
================================================
list links in a file

Usage:
  gopls [flags] links [links-flags] <filename>

Example: list links contained within a file:

	$ gopls links internal/cmd/check.go

links-flags:
  -json
    	emit document links in JSON format


================================================
FILE: gopls/internal/cmd/usage/mcp.hlp
================================================
start the gopls MCP server in headless mode

Usage:
  gopls [flags] mcp [mcp-flags]

Starts the gopls MCP server in headless mode, without needing an LSP client.
Starts the server over stdio or sse with http, depending on whether the listen flag is provided.

Examples:
  $ gopls mcp -listen=localhost:3000
  $ gopls mcp  //start over stdio
  -instructions
    	if set, print gopls' MCP instructions and exit
  -listen=string
    	the address on which to run the mcp server
  -logfile=string
    	filename to log to; if unset, logs to stderr
  -rpc.trace
    	print MCP rpc traces; cannot be used with -listen


================================================
FILE: gopls/internal/cmd/usage/prepare_rename.hlp
================================================
test validity of a rename operation at location

Usage:
  gopls [flags] prepare_rename <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls prepare_rename helper/helper.go:8:6
	$ gopls prepare_rename helper/helper.go:#53


================================================
FILE: gopls/internal/cmd/usage/references.hlp
================================================
display selected identifier's references

Usage:
  gopls [flags] references [references-flags] <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls references helper/helper.go:8:6
	$ gopls references helper/helper.go:#53

references-flags:
  -d,-declaration
    	include the declaration of the specified identifier in the results


================================================
FILE: gopls/internal/cmd/usage/remote.hlp
================================================
interact with the gopls daemon

Usage:
  gopls [flags] remote <subcommand> [arg]...

Subcommand:
  sessions  print information about current gopls sessions
  debug     start the debug server


================================================
FILE: gopls/internal/cmd/usage/rename.hlp
================================================
rename selected identifier

Usage:
  gopls [flags] rename [rename-flags] <position> <name>

Example:

	$ # 1-based location (:line:column or :#position) of the thing to change
	$ gopls rename helper/helper.go:8:6 Foo
	$ gopls rename helper/helper.go:#53 Foo

rename-flags:
  -d,-diff
    	display diffs instead of edited file content
  -l,-list
    	display names of edited files
  -preserve
    	with -write, make copies of original files
  -w,-write
    	write edited content to source files


================================================
FILE: gopls/internal/cmd/usage/semtok.hlp
================================================
show semantic tokens for the specified file

Usage:
  gopls [flags] semtok <filename>

Example: show the semantic tokens for this file:

	$ gopls semtok internal/cmd/semtok.go


================================================
FILE: gopls/internal/cmd/usage/serve.hlp
================================================
run a server for Go code using the Language Server Protocol

Usage:
  gopls [flags] serve [server-flags]
  gopls [flags] [server-flags]

The server communicates using JSONRPC2 on stdin and stdout, and is intended to be run directly as
a child of an editor process.

server-flags:
  -debug=string
    	serve debug information on the supplied address
  -listen=string
    	address on which to listen for remote connections. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. Otherwise, TCP is used.
  -listen.timeout=duration
    	when used with -listen, shut down the server when there are no connected clients for this duration
  -logfile=string
    	filename to log to. if value is "auto", then logging to a default output file is enabled
  -mcp.listen=string
    	experimental: address on which to listen for model context protocol connections. If port is localhost:0, pick a random port in localhost instead.
  -mode=string
    	no effect
  -port=int
    	port on which to run gopls for debugging purposes
  -remote.debug=string
    	when used with -remote=auto, the -debug value used to start the daemon
  -remote.listen.timeout=duration
    	when used with -remote=auto, the -listen.timeout value used to start the daemon (default 1m0s)
  -remote.logfile=string
    	when used with -remote=auto, the -logfile value used to start the daemon
  -rpc.trace
    	print the full rpc trace in lsp inspector format


================================================
FILE: gopls/internal/cmd/usage/signature.hlp
================================================
display selected identifier's signature

Usage:
  gopls [flags] signature <position>

Example:

	$ # 1-indexed location (:line:column or :#offset) of the target identifier
	$ gopls signature helper/helper.go:8:6
	$ gopls signature helper/helper.go:#53


================================================
FILE: gopls/internal/cmd/usage/stats.hlp
================================================
print workspace statistics

Usage:
  gopls [flags] stats

Load the workspace for the current directory, and output a JSON summary of
workspace information relevant to performance. As a side effect, this command
populates the gopls file cache for the current workspace.

By default, this command may include output that refers to the location or
content of user code. When the -anon flag is set, fields that may refer to user
code are hidden.

Example:
  $ gopls stats -anon
  -anon
    	hide any fields that may contain user names, file names, or source code


================================================
FILE: gopls/internal/cmd/usage/symbols.hlp
================================================
display selected file's symbols

Usage:
  gopls [flags] symbols <file>

Example:
	$ gopls symbols helper/helper.go


================================================
FILE: gopls/internal/cmd/usage/usage-v.hlp
================================================

gopls is a Go language server.

It is typically used with an editor to provide language features. When no
command is specified, gopls will default to the 'serve' command. The language
features can also be accessed via the gopls command-line interface.

For documentation of all its features, see:

   https://github.com/golang/tools/blob/master/gopls/doc/features

Usage:
  gopls help [<subject>]

Command:

Main                
  serve             run a server for Go code using the Language Server Protocol
  version           print the gopls version information
  bug               report a bug in gopls
  help              print usage information for subcommands
  api-json          print JSON describing gopls API
  licenses          print licenses of included software
                    
Features            
  call_hierarchy    display selected identifier's call hierarchy
  check             show diagnostic results for the specified file
  codeaction        list or execute code actions
  codelens          List or execute code lenses for a file
  definition        show declaration of selected identifier
  execute           Execute a gopls custom LSP command
  fix               apply suggested fixes (obsolete)
  folding_ranges    display selected file's folding ranges
  format            format the code according to the go standard
  mcp               start the gopls MCP server in headless mode
  highlight         display selected identifier's highlights
  implementation    display selected identifier's implementation
  imports           updates import statements
  remote            interact with the gopls daemon
  inspect           interact with the gopls daemon (deprecated: use 'remote')
  links             list links in a file
  prepare_rename    test validity of a rename operation at location
  references        display selected identifier's references
  rename            rename selected identifier
  semtok            show semantic tokens for the specified file
  signature         display selected identifier's signature
  stats             print workspace statistics
  symbols           display selected file's symbols
  workspace_symbol  search symbols in workspace
                    
Internal Use Only   
  vulncheck         run vulncheck analysis (internal-use only)

flags:
  -debug=string
    	serve debug information on the supplied address
  -listen=string
    	address on which to listen for remote connections. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. Otherwise, TCP is used.
  -listen.timeout=duration
    	when used with -listen, shut down the server when there are no connected clients for this duration
  -logfile=string
    	filename to log to. if value is "auto", then logging to a default output file is enabled
  -mcp.listen=string
    	experimental: address on which to listen for model context protocol connections. If port is localhost:0, pick a random port in localhost instead.
  -mode=string
    	no effect
  -otel=string
    	export telemetry to specified OpenTelemetry collector address (e.g. http://localhost:4318)
  -port=int
    	port on which to run gopls for debugging purposes
  -profile.alloc=string
    	write alloc profile to this file
  -profile.block=string
    	write block profile to this file
  -profile.cpu=string
    	write CPU profile to this file
  -profile.mem=string
    	write memory profile to this file
  -profile.trace=string
    	write trace log to this file
  -remote=string
    	forward all commands to a remote lsp specified by this flag. With no special prefix, this is assumed to be a TCP address. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. If 'auto', or prefixed by 'auto;', the remote address is automatically resolved based on the executing environment.
  -remote.debug=string
    	when used with -remote=auto, the -debug value used to start the daemon
  -remote.listen.timeout=duration
    	when used with -remote=auto, the -listen.timeout value used to start the daemon (default 1m0s)
  -remote.logfile=string
    	when used with -remote=auto, the -logfile value used to start the daemon
  -rpc.trace
    	print the full rpc trace in lsp inspector format
  -v,-verbose
    	verbose output
  -vv,-veryverbose
    	very verbose output


================================================
FILE: gopls/internal/cmd/usage/usage.hlp
================================================

gopls is a Go language server.

It is typically used with an editor to provide language features. When no
command is specified, gopls will default to the 'serve' command. The language
features can also be accessed via the gopls command-line interface.

For documentation of all its features, see:

   https://github.com/golang/tools/blob/master/gopls/doc/features

Usage:
  gopls help [<subject>]

Command:

Main                
  serve             run a server for Go code using the Language Server Protocol
  version           print the gopls version information
  bug               report a bug in gopls
  help              print usage information for subcommands
  api-json          print JSON describing gopls API
  licenses          print licenses of included software
                    
Features            
  call_hierarchy    display selected identifier's call hierarchy
  check             show diagnostic results for the specified file
  codeaction        list or execute code actions
  codelens          List or execute code lenses for a file
  definition        show declaration of selected identifier
  execute           Execute a gopls custom LSP command
  fix               apply suggested fixes (obsolete)
  folding_ranges    display selected file's folding ranges
  format            format the code according to the go standard
  mcp               start the gopls MCP server in headless mode
  highlight         display selected identifier's highlights
  implementation    display selected identifier's implementation
  imports           updates import statements
  remote            interact with the gopls daemon
  inspect           interact with the gopls daemon (deprecated: use 'remote')
  links             list links in a file
  prepare_rename    test validity of a rename operation at location
  references        display selected identifier's references
  rename            rename selected identifier
  semtok            show semantic tokens for the specified file
  signature         display selected identifier's signature
  stats             print workspace statistics
  symbols           display selected file's symbols
  workspace_symbol  search symbols in workspace

flags:
  -debug=string
    	serve debug information on the supplied address
  -listen=string
    	address on which to listen for remote connections. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. Otherwise, TCP is used.
  -listen.timeout=duration
    	when used with -listen, shut down the server when there are no connected clients for this duration
  -logfile=string
    	filename to log to. if value is "auto", then logging to a default output file is enabled
  -mcp.listen=string
    	experimental: address on which to listen for model context protocol connections. If port is localhost:0, pick a random port in localhost instead.
  -mode=string
    	no effect
  -otel=string
    	export telemetry to specified OpenTelemetry collector address (e.g. http://localhost:4318)
  -port=int
    	port on which to run gopls for debugging purposes
  -profile.alloc=string
    	write alloc profile to this file
  -profile.block=string
    	write block profile to this file
  -profile.cpu=string
    	write CPU profile to this file
  -profile.mem=string
    	write memory profile to this file
  -profile.trace=string
    	write trace log to this file
  -remote=string
    	forward all commands to a remote lsp specified by this flag. With no special prefix, this is assumed to be a TCP address. If prefixed by 'unix;', the subsequent address is assumed to be a unix domain socket. If 'auto', or prefixed by 'auto;', the remote address is automatically resolved based on the executing environment.
  -remote.debug=string
    	when used with -remote=auto, the -debug value used to start the daemon
  -remote.listen.timeout=duration
    	when used with -remote=auto, the -listen.timeout value used to start the daemon (default 1m0s)
  -remote.logfile=string
    	when used with -remote=auto, the -logfile value used to start the daemon
  -rpc.trace
    	print the full rpc trace in lsp inspector format
  -v,-verbose
    	verbose output
  -vv,-veryverbose
    	very verbose output


================================================
FILE: gopls/internal/cmd/usage/version.hlp
================================================
print the gopls version information

Usage:
  gopls [flags] version
  -json
    	outputs in json format.


================================================
FILE: gopls/internal/cmd/usage/vulncheck.hlp
================================================
run vulncheck analysis (internal-use only)

Usage:
  gopls [flags] vulncheck

	WARNING: this command is for internal-use only.

	By default, the command outputs a JSON-encoded
	golang.org/x/tools/gopls/internal/protocol/command.VulncheckResult
	message.
	Example:
	$ gopls vulncheck <packages>



================================================
FILE: gopls/internal/cmd/usage/workspace_symbol.hlp
================================================
search symbols in workspace

Usage:
  gopls [flags] workspace_symbol [workspace_symbol-flags] <query>

Example:

	$ gopls workspace_symbol -matcher fuzzy 'wsymbols'

workspace_symbol-flags:
  -matcher=string
    	specifies the type of matcher: fuzzy, fastfuzzy, casesensitive, or caseinsensitive.
    	The default is caseinsensitive.


================================================
FILE: gopls/internal/cmd/vulncheck.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"os"

	"golang.org/x/tools/gopls/internal/vulncheck/scan"
)

// vulncheck implements the vulncheck command.
// TODO(hakim): hide from the public.
type vulncheck struct {
	app *Application
}

func (v *vulncheck) Name() string   { return "vulncheck" }
func (v *vulncheck) Parent() string { return v.app.Name() }
func (v *vulncheck) Usage() string  { return "" }
func (v *vulncheck) ShortHelp() string {
	return "run vulncheck analysis (internal-use only)"
}
func (v *vulncheck) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
	WARNING: this command is for internal-use only.

	By default, the command outputs a JSON-encoded
	golang.org/x/tools/gopls/internal/protocol/command.VulncheckResult
	message.
	Example:
	$ gopls vulncheck <packages>

`)
}

func (v *vulncheck) Run(ctx context.Context, args ...string) error {
	if err := scan.Main(ctx, args...); err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
	return nil
}


================================================
FILE: gopls/internal/cmd/workspace_symbol.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package cmd

import (
	"context"
	"flag"
	"fmt"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/tool"
)

// workspaceSymbol implements the workspace_symbol verb for gopls.
type workspaceSymbol struct {
	Matcher string `flag:"matcher" help:"specifies the type of matcher: fuzzy, fastfuzzy, casesensitive, or caseinsensitive.\nThe default is caseinsensitive."`

	app *Application
}

func (r *workspaceSymbol) Name() string      { return "workspace_symbol" }
func (r *workspaceSymbol) Parent() string    { return r.app.Name() }
func (r *workspaceSymbol) Usage() string     { return "[workspace_symbol-flags] <query>" }
func (r *workspaceSymbol) ShortHelp() string { return "search symbols in workspace" }
func (r *workspaceSymbol) DetailedHelp(f *flag.FlagSet) {
	fmt.Fprint(f.Output(), `
Example:

	$ gopls workspace_symbol -matcher fuzzy 'wsymbols'

workspace_symbol-flags:
`)
	printFlagDefaults(f)
}

func (r *workspaceSymbol) Run(ctx context.Context, args ...string) error {
	if len(args) != 1 {
		return tool.CommandLineErrorf("workspace_symbol expects 1 argument")
	}

	opts := r.app.options
	r.app.options = func(o *settings.Options) {
		if opts != nil {
			opts(o)
		}
		switch strings.ToLower(r.Matcher) {
		case "fuzzy":
			o.SymbolMatcher = settings.SymbolFuzzy
		case "casesensitive":
			o.SymbolMatcher = settings.SymbolCaseSensitive
		case "fastfuzzy":
			o.SymbolMatcher = settings.SymbolFastFuzzy
		default:
			o.SymbolMatcher = settings.SymbolCaseInsensitive
		}
	}

	cli, _, err := r.app.connect(ctx)
	if err != nil {
		return err
	}
	defer cli.terminate(ctx)

	p := protocol.WorkspaceSymbolParams{
		Query: args[0],
	}

	symbols, err := cli.server.Symbol(ctx, &p)
	if err != nil {
		return err
	}
	for _, s := range symbols {
		f, err := cli.openFile(ctx, s.Location.URI)
		if err != nil {
			return err
		}
		span, err := f.locationSpan(s.Location)
		if err != nil {
			return err
		}
		fmt.Printf("%s %s %s\n", span, s.Name, s.Kind)
	}

	return nil
}


================================================
FILE: gopls/internal/debug/flight.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.25

package debug

import (
	"bufio"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/exec"
	"path/filepath"
	"runtime/trace"
	"strings"
	"sync"
	"syscall"
	"time"
)

var (
	traceviewersMu sync.Mutex
	traceviewers   []*os.Process

	kill        = (*os.Process).Kill // windows, plan9; UNIX impl kills whole process group
	sysProcAttr syscall.SysProcAttr  // UNIX configuration to create process group
)

// KillTraceViewers kills all "go tool trace" processes started by
// /flightrecorder requests, for use in tests (see #74668).
func KillTraceViewers() {
	traceviewersMu.Lock()
	for _, p := range traceviewers {
		kill(p) // ignore error
	}
	traceviewers = nil
	traceviewersMu.Unlock()
}

// The FlightRecorder is a global resource, so create at most one per process.
var getRecorder = sync.OnceValues(func() (*trace.FlightRecorder, error) {
	fr := trace.NewFlightRecorder(trace.FlightRecorderConfig{
		// half a minute is usually enough to know "what just happened?"
		MinAge: 30 * time.Second,
	})
	if err := fr.Start(); err != nil {
		return nil, err
	}
	return fr, nil
})

func startFlightRecorder() (http.HandlerFunc, error) {
	fr, err := getRecorder()
	if err != nil {
		return nil, err
	}

	// Return a handler that writes the most recent flight record,
	// starts a trace viewer server, and redirects to it.
	return func(w http.ResponseWriter, r *http.Request) {
		errorf := func(format string, args ...any) {
			msg := fmt.Sprintf(format, args...)
			http.Error(w, msg, http.StatusInternalServerError)
		}

		// Write the most recent flight record into a temp file.
		f, err := os.CreateTemp("", "flightrecord")
		if err != nil {
			errorf("can't create temp file for flight record: %v", err)
			return
		}
		if _, err := fr.WriteTo(f); err != nil {
			f.Close() // ignore error
			errorf("failed to write flight record: %s", err)
			return
		}
		if err := f.Close(); err != nil {
			errorf("failed to close flight record: %s", err)
			return
		}
		tracefile, err := filepath.Abs(f.Name())
		if err != nil {
			errorf("can't absolutize name of trace file: %v", err)
			return
		}

		// Run 'go tool trace' to start a new trace-viewer
		// web server process. It will run until gopls terminates.
		// (It would be nicer if we could just link it in; see #66843.)
		cmd := exec.Command("go", "tool", "trace", tracefile)
		cmd.SysProcAttr = &sysProcAttr

		// Don't connect trace's std{out,err} to our os.Stderr directly,
		// otherwise the child may outlive the parent in tests,
		// and 'go test' will complain about unclosed pipes.
		// Instead, interpose a pipe that will close when gopls exits.
		// See CL 677262 for a better solution (a cmd/trace flag).
		// (#66843 is of course better still.)
		// Also, this notifies us of the server's readiness and URL.
		urlC := make(chan string)
		{
			r, w, err := os.Pipe()
			if err != nil {
				errorf("can't create pipe: %v", err)
				return
			}
			go func() {
				// Copy from the pipe to stderr,
				// keeping an eye out for the "listening on URL" string.
				scan := bufio.NewScanner(r)
				for scan.Scan() {
					line := scan.Text()
					if _, url, ok := strings.Cut(line, "Trace viewer is listening on "); ok {
						urlC <- url
					}
					fmt.Fprintln(os.Stderr, line)
				}
				if err := scan.Err(); err != nil {
					log.Printf("reading from pipe to cmd/trace: %v", err)
				}
			}()
			cmd.Stderr = w
			cmd.Stdout = w
		}

		// Suppress the usual cmd/trace behavior of opening a new
		// browser tab by setting BROWSER to /usr/bin/true (a no-op).
		cmd.Env = append(os.Environ(), "BROWSER=true")
		if err := cmd.Start(); err != nil {
			errorf("failed to start trace server: %s", err)
			return
		}

		// Save the process so we can kill it when tests finish.
		traceviewersMu.Lock()
		traceviewers = append(traceviewers, cmd.Process)
		traceviewersMu.Unlock()

		// Some of the CI builders can be quite heavily loaded.
		// Give them an extra grace period.
		timeout := 10 * time.Second
		if os.Getenv("GO_BUILDER_NAME") != "" {
			timeout = 1 * time.Minute
		}

		select {
		case addr := <-urlC:
			// Success! Send a redirect to the new location.
			// (This URL bypasses the help screen at /.)
			http.Redirect(w, r, addr+"/trace?view=proc", 302)

		case <-r.Context().Done():
			errorf("canceled")

		case <-time.After(timeout):
			errorf("trace viewer failed to start within %v", timeout)
		}
	}, nil
}


================================================
FILE: gopls/internal/debug/flight_go124.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.25

package debug

import (
	"errors"
	"net/http"
)

func startFlightRecorder() (http.HandlerFunc, error) {
	return nil, errors.ErrUnsupported
}

func KillTraceViewers() {}


================================================
FILE: gopls/internal/debug/flight_unix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.25 && unix

package debug

import (
	"os"
	"syscall"
)

func init() {
	// UNIX: kill the whole process group, since
	// "go tool trace" starts a cmd/trace child.
	kill = killGroup
	sysProcAttr.Setpgid = true
}

func killGroup(p *os.Process) error {
	return syscall.Kill(-p.Pid, syscall.SIGKILL)
}


================================================
FILE: gopls/internal/debug/info.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package debug exports debug information for gopls.
package debug

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"os"
	"runtime"
	"runtime/debug"
	"strings"

	"golang.org/x/tools/gopls/internal/version"
)

type PrintMode int

const (
	PlainText = PrintMode(iota)
	Markdown
	HTML
	JSON
)

// ServerVersion is the format used by gopls to report its version to the
// client. This format is structured so that the client can parse it easily.
type ServerVersion struct {
	*debug.BuildInfo
	Version string
}

// VersionInfo returns the build info for the gopls process. If it was not
// built in module mode, we return a GOPATH-specific message with the
// hardcoded version.
func VersionInfo() *ServerVersion {
	if info, ok := debug.ReadBuildInfo(); ok {
		return &ServerVersion{
			Version:   version.Version(),
			BuildInfo: info,
		}
	}
	return &ServerVersion{
		Version: version.Version(),
		BuildInfo: &debug.BuildInfo{
			Path:      "gopls, built in GOPATH mode",
			GoVersion: runtime.Version(),
		},
	}
}

// writeServerInfo writes HTML debug info to w for the instance.
func (i *Instance) writeServerInfo(out *bytes.Buffer) {
	workDir, _ := os.Getwd()
	section(out, HTML, "server instance", func() {
		fmt.Fprintf(out, "Start time: %v\n", i.StartTime)
		fmt.Fprintf(out, "LogFile: %s\n", i.Logfile)
		fmt.Fprintf(out, "pid: %d\n", os.Getpid())
		fmt.Fprintf(out, "Working directory: %s\n", workDir)
		fmt.Fprintf(out, "Address: %s\n", i.ServerAddress)
		fmt.Fprintf(out, "Debug address: %s\n", i.DebugAddress())
	})
	WriteVersionInfo(out, true, HTML)
	section(out, HTML, "Command Line", func() {
		fmt.Fprintf(out, "<a href=/debug/pprof/cmdline>cmdline</a>")
	})
}

// WriteVersionInfo writes version information to w, using the output format
// specified by mode. verbose controls whether additional information is
// written, including section headers.
func WriteVersionInfo(out *bytes.Buffer, verbose bool, mode PrintMode) {
	info := VersionInfo()
	if mode == JSON {
		writeVersionInfoJSON(out, info)
		return
	}

	if !verbose {
		writeBuildInfo(out, info, false, mode)
		return
	}
	section(out, mode, "Build info", func() {
		writeBuildInfo(out, info, true, mode)
	})
}

func writeVersionInfoJSON(out *bytes.Buffer, info *ServerVersion) {
	data, err := json.MarshalIndent(info, "", "\t")
	if err != nil {
		panic(err) // can't happen
	}
	out.Write(data)
}

func section(w io.Writer, mode PrintMode, title string, body func()) {
	switch mode {
	case PlainText:
		fmt.Fprintln(w, title)
		fmt.Fprintln(w, strings.Repeat("-", len(title)))
		body()
	case Markdown:
		fmt.Fprintf(w, "#### %s\n\n```\n", title)
		body()
		fmt.Fprintf(w, "```\n")
	case HTML:
		fmt.Fprintf(w, "<h3>%s</h3>\n<pre>\n", title)
		body()
		fmt.Fprint(w, "</pre>\n")
	}
}

func writeBuildInfo(w io.Writer, info *ServerVersion, verbose bool, mode PrintMode) {
	fmt.Fprintf(w, "%v %v\n", info.Path, version.Version())
	if !verbose {
		return
	}
	printModuleInfo(w, info.Main, mode)
	for _, dep := range info.Deps {
		printModuleInfo(w, *dep, mode)
	}
	fmt.Fprintf(w, "go: %v\n", info.GoVersion)
}

func printModuleInfo(w io.Writer, m debug.Module, _ PrintMode) {
	fmt.Fprintf(w, "    %s@%s", m.Path, m.Version)
	if m.Sum != "" {
		fmt.Fprintf(w, " %s", m.Sum)
	}
	if m.Replace != nil {
		fmt.Fprintf(w, " => %v", m.Replace.Path)
	}
	fmt.Fprintf(w, "\n")
}


================================================
FILE: gopls/internal/debug/info_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package debug exports debug information for gopls.
package debug

import (
	"bytes"
	"encoding/json"
	"runtime"
	"testing"

	"golang.org/x/tools/gopls/internal/version"
)

func TestPrintVersionInfoJSON(t *testing.T) {
	buf := new(bytes.Buffer)
	WriteVersionInfo(buf, true, JSON)
	res := buf.Bytes()

	var got ServerVersion
	if err := json.Unmarshal(res, &got); err != nil {
		t.Fatalf("unexpected output: %v\n%s", err, res)
	}
	if g, w := got.GoVersion, runtime.Version(); g != w {
		t.Errorf("go version = %v, want %v", g, w)
	}
	if g, w := got.Version, version.Version(); g != w {
		t.Errorf("gopls version = %v, want %v", g, w)
	}
	// Other fields of BuildInfo may not be available during test.
}

func TestPrintVersionInfoPlainText(t *testing.T) {
	buf := new(bytes.Buffer)
	WriteVersionInfo(buf, true, PlainText)
	res := buf.Bytes()

	// Other fields of BuildInfo may not be available during test.
	wantGoplsVersion, wantGoVersion := version.Version(), runtime.Version()
	if !bytes.Contains(res, []byte(wantGoplsVersion)) || !bytes.Contains(res, []byte(wantGoVersion)) {
		t.Errorf("plaintext output = %q,\nwant (version: %v, go: %v)", res, wantGoplsVersion, wantGoVersion)
	}
}


================================================
FILE: gopls/internal/debug/log/log.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package log provides helper methods for exporting log events to the
// internal/event package.
package log

import (
	"context"
	"fmt"

	label1 "golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/label"
)

// Level parameterizes log severity.
type Level int

const (
	_ Level = iota
	Error
	Warning
	Info
	Debug
	Trace
)

// Log exports a log event labeled with level l.
func (l Level) Log(ctx context.Context, msg string) {
	event.Log(ctx, msg, label1.Level.Of(int(l)))
}

// Logf formats and exports a log event labeled with level l.
func (l Level) Logf(ctx context.Context, format string, args ...any) {
	l.Log(ctx, fmt.Sprintf(format, args...))
}

// LabeledLevel extracts the labeled log l
func LabeledLevel(lm label.Map) Level {
	return Level(label1.Level.Get(lm))
}


================================================
FILE: gopls/internal/debug/metrics.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug

import (
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/label"
	"golang.org/x/tools/internal/jsonrpc2"
)

var (
	// the distributions we use for histograms
	bytesDistribution   = []int64{1 << 10, 1 << 11, 1 << 12, 1 << 14, 1 << 16, 1 << 20}
	secondsDistribution = []float64{
		0.0001, // 0.1ms
		0.0005, // 0.5ms
		0.001,  // 1ms
		0.002,  // 2ms
		0.005,  // 5ms
		0.01,   // 10ms
		0.05,   // 50ms
		0.1,    // 100ms
		0.5,    // 500ms
		1,      // 1s
		5,      // 5s
		10,     // 10s
		50,     // 50s
		100,    // 1m40s
		500,    // 8m20s
		1000,   // 16m40s
	}

	receivedBytes = metric.HistogramInt64{
		Name:        "received_bytes",
		Description: "Distribution of received bytes, by method.",
		Keys:        []label.Key{jsonrpc2.RPCDirection, jsonrpc2.Method},
		Buckets:     bytesDistribution,
	}

	sentBytes = metric.HistogramInt64{
		Name:        "sent_bytes",
		Description: "Distribution of sent bytes, by method.",
		Keys:        []label.Key{jsonrpc2.RPCDirection, jsonrpc2.Method},
		Buckets:     bytesDistribution,
	}

	latency = metric.HistogramFloat64{
		Name:        "latency",
		Description: "Distribution of latency in seconds, by method.",
		Keys:        []label.Key{jsonrpc2.RPCDirection, jsonrpc2.Method},
		Buckets:     secondsDistribution,
	}

	started = metric.Scalar{
		Name:        "started",
		Description: "Count of RPCs started by method.",
		Keys:        []label.Key{jsonrpc2.RPCDirection, jsonrpc2.Method},
	}

	completed = metric.Scalar{
		Name:        "completed",
		Description: "Count of RPCs completed by method and status.",
		Keys:        []label.Key{jsonrpc2.RPCDirection, jsonrpc2.Method, jsonrpc2.StatusCode},
	}
)

func registerMetrics(m *metric.Config) {
	receivedBytes.Record(m, jsonrpc2.ReceivedBytes)
	sentBytes.Record(m, jsonrpc2.SentBytes)
	latency.Record(m, jsonrpc2.Latency)
	started.Count(m, jsonrpc2.Started)
	completed.Count(m, jsonrpc2.Latency)
}


================================================
FILE: gopls/internal/debug/rpc.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug

import (
	"context"
	"fmt"
	"html/template"
	"net/http"
	"sort"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/label"
	"golang.org/x/tools/internal/jsonrpc2"
)

var RPCTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}RPC Information{{end}}
{{define "body"}}
	<H2>Inbound</H2>
	{{template "rpcSection" .Inbound}}
	<H2>Outbound</H2>
	{{template "rpcSection" .Outbound}}
{{end}}
{{define "rpcSection"}}
	{{range .}}<P>
		<b>{{.Method}}</b> {{.Started}} <a href="/trace/{{.Method}}">traces</a> ({{.InProgress}} in progress)
		<br>
		<i>Latency</i> {{with .Latency}}{{.Mean}} ({{.Min}}<{{.Max}}){{end}}
		<i>By bucket</i> 0s {{range .Latency.Values}}{{if gt .Count 0}}<b>{{.Count}}</b> {{.Limit}} {{end}}{{end}}
		<br>
		<i>Received</i> {{.Received}} (avg. {{.ReceivedMean}})
		<i>Sent</i> {{.Sent}} (avg. {{.SentMean}})
		<br>
		<i>Result codes</i> {{range .Codes}}{{.Key}}={{.Count}} {{end}}
		</P>
	{{end}}
{{end}}
`))

type Rpcs struct { // exported for testing
	mu       sync.Mutex
	Inbound  []*rpcStats // stats for incoming lsp rpcs sorted by method name
	Outbound []*rpcStats // stats for outgoing lsp rpcs sorted by method name
}

type rpcStats struct {
	Method    string
	Started   int64
	Completed int64

	Latency  rpcTimeHistogram
	Received byteUnits
	Sent     byteUnits
	Codes    []*rpcCodeBucket
}

type rpcTimeHistogram struct {
	Sum    time.Duration
	Count  int64
	Min    time.Duration
	Max    time.Duration
	Values []rpcTimeBucket
}

type rpcTimeBucket struct {
	Limit time.Duration
	Count int64
}

type rpcCodeBucket struct {
	Key   string
	Count int64
}

func (r *Rpcs) ProcessEvent(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	r.mu.Lock()
	defer r.mu.Unlock()
	switch {
	case event.IsStart(ev):
		if _, stats := r.getRPCSpan(ctx); stats != nil {
			stats.Started++
		}
	case event.IsEnd(ev):
		span, stats := r.getRPCSpan(ctx)
		if stats != nil {
			endRPC(span, stats)
		}
	case event.IsMetric(ev):
		sent := byteUnits(jsonrpc2.SentBytes.Get(lm))
		rec := byteUnits(jsonrpc2.ReceivedBytes.Get(lm))
		if sent != 0 || rec != 0 {
			if _, stats := r.getRPCSpan(ctx); stats != nil {
				stats.Sent += sent
				stats.Received += rec
			}
		}
	}
	return ctx
}

func endRPC(span *export.Span, stats *rpcStats) {
	// update the basic counts
	stats.Completed++

	// get and record the status code
	if status := getStatusCode(span); status != "" {
		var b *rpcCodeBucket
		for c, entry := range stats.Codes {
			if entry.Key == status {
				b = stats.Codes[c]
				break
			}
		}
		if b == nil {
			b = &rpcCodeBucket{Key: status}
			stats.Codes = append(stats.Codes, b)
			sort.Slice(stats.Codes, func(i int, j int) bool {
				return stats.Codes[i].Key < stats.Codes[j].Key
			})
		}
		b.Count++
	}

	// calculate latency if this was an rpc span
	elapsedTime := span.Finish().At().Sub(span.Start().At())
	if stats.Latency.Count == 0 {
		stats.Latency.Min = elapsedTime
		stats.Latency.Max = elapsedTime
	} else {
		stats.Latency.Min = min(stats.Latency.Min, elapsedTime)
		stats.Latency.Max = max(stats.Latency.Max, elapsedTime)
	}
	stats.Latency.Count++
	stats.Latency.Sum += elapsedTime
	for i := range stats.Latency.Values {
		if stats.Latency.Values[i].Limit > elapsedTime {
			stats.Latency.Values[i].Count++
			break
		}
	}
}

func (r *Rpcs) getRPCSpan(ctx context.Context) (*export.Span, *rpcStats) {
	// get the span
	span := export.GetSpan(ctx)
	if span == nil {
		return nil, nil
	}
	// use the span start event look up the correct stats block
	// we do this because it prevents us matching a sub span
	return span, r.getRPCStats(span.Start())
}

func (r *Rpcs) getRPCStats(lm label.Map) *rpcStats {
	method := jsonrpc2.Method.Get(lm)
	if method == "" {
		return nil
	}
	set := &r.Inbound
	if jsonrpc2.RPCDirection.Get(lm) != jsonrpc2.Inbound {
		set = &r.Outbound
	}
	// get the record for this method
	index := sort.Search(len(*set), func(i int) bool {
		return (*set)[i].Method >= method
	})

	if index < len(*set) && (*set)[index].Method == method {
		return (*set)[index]
	}

	old := *set
	*set = make([]*rpcStats, len(old)+1)
	copy(*set, old[:index])
	copy((*set)[index+1:], old[index:])
	stats := &rpcStats{Method: method}
	stats.Latency.Values = make([]rpcTimeBucket, len(secondsDistribution))
	for i, m := range secondsDistribution {
		stats.Latency.Values[i].Limit = time.Duration(m * float64(time.Second))
	}
	(*set)[index] = stats
	return stats
}

func (s *rpcStats) InProgress() int64       { return s.Started - s.Completed }
func (s *rpcStats) SentMean() byteUnits     { return s.Sent / byteUnits(s.Started) }
func (s *rpcStats) ReceivedMean() byteUnits { return s.Received / byteUnits(s.Started) }

func (h *rpcTimeHistogram) Mean() time.Duration { return h.Sum / time.Duration(h.Count) }

func getStatusCode(span *export.Span) string {
	for _, ev := range span.Events() {
		if status := jsonrpc2.StatusCode.Get(ev); status != "" {
			return status
		}
	}
	return ""
}

func (r *Rpcs) getData(req *http.Request) any {
	return r
}

func units(v float64, suffixes []string) string {
	s := ""
	for _, s = range suffixes {
		n := v / 1000
		if n < 1 {
			break
		}
		v = n
	}
	return fmt.Sprintf("%.2f%s", v, s)
}

type byteUnits float64

func (v byteUnits) String() string {
	return units(float64(v), []string{"B", "KB", "MB", "GB", "TB"})
}


================================================
FILE: gopls/internal/debug/serve.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"html/template"
	"io"
	stdlog "log"
	"net"
	"net/http"
	"net/http/pprof"
	"os"
	"path"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/debug/log"
	"golang.org/x/tools/gopls/internal/file"
	label1 "golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	versionpkg "golang.org/x/tools/gopls/internal/version"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/export/otel"
	"golang.org/x/tools/internal/event/export/prometheus"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

type contextKeyType int

const (
	instanceKey contextKeyType = iota
	traceKey
)

// An Instance holds all debug information associated with a gopls instance.
type Instance struct {
	Logfile       string
	StartTime     time.Time
	ServerAddress string

	LogWriter io.Writer

	exporter event.Exporter

	prometheus *prometheus.Exporter
	rpcs       *Rpcs
	traces     *traces
	otel       *otel.Exporter
	State      *State

	serveMu              sync.Mutex
	debugAddress         string
	listenedDebugAddress string
}

// State holds debugging information related to the server state.
type State struct {
	mu      sync.Mutex
	clients []*Client
	servers []*Server
}

func (st *State) Bugs() []bug.Bug {
	return bug.List()
}

// Caches returns the set of Cache objects currently being served.
func (st *State) Caches() []*cache.Cache {
	var caches []*cache.Cache
	seen := make(map[string]struct{})
	for _, client := range st.Clients() {
		cache := client.Session.Cache()
		if _, found := seen[cache.ID()]; found {
			continue
		}
		seen[cache.ID()] = struct{}{}
		caches = append(caches, cache)
	}
	return caches
}

// Cache returns the Cache that matches the supplied id.
func (st *State) Cache(id string) *cache.Cache {
	for _, c := range st.Caches() {
		if c.ID() == id {
			return c
		}
	}
	return nil
}

// Analysis returns the global Analysis template value.
func (st *State) Analysis() (_ analysisTmpl) { return }

type analysisTmpl struct{}

func (analysisTmpl) AnalyzerRunTimes() []cache.LabelDuration { return cache.AnalyzerRunTimes() }

// Sessions returns the set of Session objects currently being served.
func (st *State) Sessions() []*cache.Session {
	var sessions []*cache.Session
	for _, client := range st.Clients() {
		sessions = append(sessions, client.Session)
	}
	return sessions
}

// Session returns the Session that matches the supplied id.
func (st *State) Session(id string) *cache.Session {
	for _, s := range st.Sessions() {
		if s.ID() == id {
			return s
		}
	}
	return nil
}

// Views returns the set of View objects currently being served.
func (st *State) Views() []*cache.View {
	var views []*cache.View
	for _, s := range st.Sessions() {
		views = append(views, s.Views()...)
	}
	return views
}

// View returns the View that matches the supplied id.
func (st *State) View(id string) *cache.View {
	for _, s := range st.Sessions() {
		if v, err := s.View(id); err == nil {
			return v
		}
	}
	return nil // not found
}

// Clients returns the set of Clients currently being served.
func (st *State) Clients() []*Client {
	st.mu.Lock()
	defer st.mu.Unlock()
	clients := make([]*Client, len(st.clients))
	copy(clients, st.clients)
	return clients
}

// Client returns the Client matching the supplied id.
func (st *State) Client(id string) *Client {
	for _, c := range st.Clients() {
		if c.Session.ID() == id {
			return c
		}
	}
	return nil
}

// Servers returns the set of Servers the instance is currently connected to.
func (st *State) Servers() []*Server {
	st.mu.Lock()
	defer st.mu.Unlock()
	servers := make([]*Server, len(st.servers))
	copy(servers, st.servers)
	return servers
}

// A Client is an incoming connection from a remote client.
type Client struct {
	Session      *cache.Session
	DebugAddress string
	Logfile      string
	GoplsPath    string
	ServerID     string
	Service      protocol.Server
}

// A Server is an outgoing connection to a remote LSP server.
type Server struct {
	ID           string
	DebugAddress string
	Logfile      string
	GoplsPath    string
	ClientID     string
}

// addClient adds a client to the set being served.
func (st *State) addClient(session *cache.Session) {
	st.mu.Lock()
	defer st.mu.Unlock()
	st.clients = append(st.clients, &Client{Session: session})
}

// dropClient removes a client from the set being served.
func (st *State) dropClient(session *cache.Session) {
	st.mu.Lock()
	defer st.mu.Unlock()
	for i, c := range st.clients {
		if c.Session == session {
			copy(st.clients[i:], st.clients[i+1:])
			st.clients[len(st.clients)-1] = nil
			st.clients = st.clients[:len(st.clients)-1]
			return
		}
	}
}

// updateServer updates a server to the set being queried. In practice, there should
// be at most one remote server.
func (st *State) updateServer(server *Server) {
	st.mu.Lock()
	defer st.mu.Unlock()
	for i, existing := range st.servers {
		if existing.ID == server.ID {
			// Replace, rather than mutate, to avoid a race.
			newServers := make([]*Server, len(st.servers))
			copy(newServers, st.servers[:i])
			newServers[i] = server
			copy(newServers[i+1:], st.servers[i+1:])
			st.servers = newServers
			return
		}
	}
	st.servers = append(st.servers, server)
}

// dropServer drops a server from the set being queried.
func (st *State) dropServer(id string) {
	st.mu.Lock()
	defer st.mu.Unlock()
	for i, s := range st.servers {
		if s.ID == id {
			copy(st.servers[i:], st.servers[i+1:])
			st.servers[len(st.servers)-1] = nil
			st.servers = st.servers[:len(st.servers)-1]
			return
		}
	}
}

// an http.ResponseWriter that filters writes
type filterResponse struct {
	w    http.ResponseWriter
	edit func([]byte) []byte
}

func (c filterResponse) Header() http.Header {
	return c.w.Header()
}

func (c filterResponse) Write(buf []byte) (int, error) {
	ans := c.edit(buf)
	return c.w.Write(ans)
}

func (c filterResponse) WriteHeader(n int) {
	c.w.WriteHeader(n)
}

// replace annoying nuls by spaces
func cmdline(w http.ResponseWriter, r *http.Request) {
	fake := filterResponse{
		w: w,
		edit: func(buf []byte) []byte {
			return bytes.ReplaceAll(buf, []byte{0}, []byte{' '})
		},
	}
	pprof.Cmdline(fake, r)
}

func (i *Instance) getCache(r *http.Request) any {
	return i.State.Cache(path.Base(r.URL.Path))
}

func (i *Instance) getAnalysis(r *http.Request) any {
	return i.State.Analysis()
}

func (i *Instance) getSession(r *http.Request) any {
	return i.State.Session(path.Base(r.URL.Path))
}

func (i *Instance) getClient(r *http.Request) any {
	return i.State.Client(path.Base(r.URL.Path))
}

func (i *Instance) getServer(r *http.Request) any {
	i.State.mu.Lock()
	defer i.State.mu.Unlock()
	id := path.Base(r.URL.Path)
	for _, s := range i.State.servers {
		if s.ID == id {
			return s
		}
	}
	return nil
}

type FileWithKind interface {
	file.Handle
	Kind() file.Kind // (overlay files only)
}

// /file/{session}/{identifier}. Returns a [FileWithKind].
func (i *Instance) getFile(r *http.Request) any {
	s := i.State.Session(r.PathValue("session"))
	if s == nil {
		return nil
	}
	identifier := r.PathValue("identifier")
	for _, o := range s.Overlays() {
		// TODO(adonovan): understand and document this comparison.
		if o.Identity().Hash.String() == identifier {
			return o
		}
	}
	return nil
}

type MetadataInfo struct {
	SessionID string
	ViewID    string
	Graph     *metadata.Graph
}

// /metadata/{session}/{view}. Returns a [*MetadataInfo].
func (i *Instance) getMetadata(r *http.Request) any {
	session := i.State.Session(r.PathValue("session"))
	if session == nil {
		return nil
	}

	v, err := session.View(r.PathValue("view"))
	if err != nil {
		stdlog.Printf("/metadata: %v", err)
		return nil // no found
	}

	snapshot, release, err := v.Snapshot()
	if err != nil {
		stdlog.Printf("/metadata: failed to get latest snapshot: %v", err)
		return nil
	}
	defer release()
	return &MetadataInfo{
		SessionID: session.ID(),
		ViewID:    v.ID(),
		Graph:     snapshot.MetadataGraph(),
	}
}

type PackageInfo struct {
	SessionID   string
	ViewID      string
	Package     *cache.Package
	Diagnostics map[protocol.DocumentURI][]*cache.Diagnostic
}

// /package/{session}/{view}/{id...}. Returns a [*PackageInfo].
func (i *Instance) getPackage(r *http.Request) any {
	// TODO(adonovan): shouldn't we report an HTTP error in all
	// these early returns? Same for getMetadata.
	session := i.State.Session(r.PathValue("session"))
	if session == nil {
		return nil // not found
	}

	v, err := session.View(r.PathValue("view"))
	if err != nil {
		stdlog.Printf("/package: %v", err)
		return nil // not found
	}

	id := r.PathValue("id")

	snapshot, release, err := v.Snapshot()
	if err != nil {
		stdlog.Printf("/package: failed to get latest snapshot: %v", err)
		return nil
	}
	defer release()

	pkgs, err := snapshot.TypeCheck(r.Context(), cache.PackageID(id))
	if err != nil {
		stdlog.Printf("/package: failed to typecheck package %q: %v", id, err)
		return nil
	}

	// (PackageDiagnostics is redundant w.r.t. TypeCheck but it's
	// the only way to access type errors in cache.Diagnostic form.)
	diags, err := snapshot.PackageDiagnostics(r.Context(), cache.PackageID(id))
	if err != nil {
		stdlog.Printf("/package: failed to typecheck package %q: %v", id, err)
		return nil
	}

	return &PackageInfo{
		SessionID:   session.ID(),
		ViewID:      v.ID(),
		Package:     pkgs[0],
		Diagnostics: diags,
	}
}

func (i *Instance) getInfo(r *http.Request) any {
	buf := &bytes.Buffer{}
	i.writeServerInfo(buf)
	return template.HTML(buf.String())
}

func (i *Instance) AddService(s protocol.Server, session *cache.Session) {
	for _, c := range i.State.clients {
		if c.Session == session {
			c.Service = s
			return
		}
	}
	stdlog.Printf("unable to find a Client to add the protocol.Server to")
}

func getMemory(_ *http.Request) any {
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	return m
}

func init() {
	event.SetExporter(makeGlobalExporter(os.Stderr))
}

func GetInstance(ctx context.Context) *Instance {
	if ctx == nil {
		return nil
	}
	v := ctx.Value(instanceKey)
	if v == nil {
		return nil
	}
	return v.(*Instance)
}

// WithInstance creates debug instance ready for use using the supplied
// configuration and stores it in the returned context.
func WithInstance(ctx context.Context, otelEndpoint string) context.Context {
	i := &Instance{
		StartTime: time.Now(),
	}
	i.LogWriter = os.Stderr
	i.prometheus = prometheus.New()
	i.rpcs = &Rpcs{}
	i.traces = &traces{}
	i.State = &State{}
	if otelEndpoint != "" {
		i.otel = otel.NewExporter(ctx,
			otel.WithEndpoint(otelEndpoint),
			otel.WithServiceName("gopls"),
			otel.WithServiceVersion(versionpkg.Version()))
	}
	i.exporter = makeInstanceExporter(i)
	return context.WithValue(ctx, instanceKey, i)
}

// SetLogFile sets the logfile for use with this instance.
func (i *Instance) SetLogFile(logfile string, isDaemon bool) (func(), error) {
	// TODO: probably a better solution for deferring closure to the caller would
	// be for the debug instance to itself be closed, but this fixes the
	// immediate bug of logs not being captured.
	closeLog := func() {}
	if logfile != "" {
		if logfile == "auto" {
			if isDaemon {
				logfile = filepath.Join(os.TempDir(), fmt.Sprintf("gopls-daemon-%d.log", os.Getpid()))
			} else {
				logfile = filepath.Join(os.TempDir(), fmt.Sprintf("gopls-%d.log", os.Getpid()))
			}
		}
		f, err := os.Create(logfile)
		if err != nil {
			return nil, fmt.Errorf("unable to create log file: %w", err)
		}
		closeLog = func() {
			defer f.Close()
		}
		stdlog.SetOutput(io.MultiWriter(os.Stderr, f))
		i.LogWriter = f
	}
	i.Logfile = logfile
	return closeLog, nil
}

// Serve starts and runs a debug server in the background on the given addr.
// It also logs the port the server starts on, to allow for :0 auto assigned
// ports.
func (i *Instance) Serve(ctx context.Context, addr string) (string, error) {
	stdlog.SetFlags(stdlog.Lshortfile)
	if addr == "" {
		return "", nil
	}
	i.serveMu.Lock()
	defer i.serveMu.Unlock()

	if i.listenedDebugAddress != "" {
		// Already serving. Return the bound address.
		return i.listenedDebugAddress, nil
	}

	i.debugAddress = addr
	listener, err := net.Listen("tcp", i.debugAddress)
	if err != nil {
		return "", err
	}
	i.listenedDebugAddress = listener.Addr().String()

	port := listener.Addr().(*net.TCPAddr).Port
	if strings.HasSuffix(i.debugAddress, ":0") {
		stdlog.Printf("debug server listening at http://localhost:%d", port)
	}
	event.Log(ctx, "Debug serving", label1.Port.Of(port))
	go func() {
		mux := http.NewServeMux()
		mux.HandleFunc("/", render(MainTmpl, func(*http.Request) any { return i }))
		mux.HandleFunc("/debug/", render(DebugTmpl, nil))
		mux.HandleFunc("/debug/pprof/", pprof.Index)
		mux.HandleFunc("/debug/pprof/cmdline", cmdline)
		mux.HandleFunc("/debug/pprof/profile", pprof.Profile)
		mux.HandleFunc("/debug/pprof/symbol", pprof.Symbol)
		mux.HandleFunc("/debug/pprof/trace", pprof.Trace)

		if h, err := startFlightRecorder(); err != nil {
			stdlog.Printf("failed to start flight recorder: %v", err) // e.g. go1.24
		} else {
			mux.HandleFunc("/flightrecorder", h)
		}

		if i.prometheus != nil {
			mux.HandleFunc("/metrics/", i.prometheus.Serve)
		}
		if i.rpcs != nil {
			mux.HandleFunc("/rpc/", render(RPCTmpl, i.rpcs.getData))
		}
		if i.traces != nil {
			mux.HandleFunc("/trace/", render(TraceTmpl, i.traces.getData))
		}
		mux.HandleFunc("/analysis/", render(AnalysisTmpl, i.getAnalysis))
		mux.HandleFunc("/cache/", render(CacheTmpl, i.getCache))
		mux.HandleFunc("/session/", render(SessionTmpl, i.getSession))
		mux.HandleFunc("/client/", render(ClientTmpl, i.getClient))
		mux.HandleFunc("/server/", render(ServerTmpl, i.getServer))
		mux.HandleFunc("/file/{session}/{identifier}", render(FileTmpl, i.getFile))
		mux.HandleFunc("/metadata/{session}/{view}/", render(MetadataTmpl, i.getMetadata))
		mux.HandleFunc("/package/{session}/{view}/{id...}", render(PackageTmpl, i.getPackage))
		mux.HandleFunc("/info", render(InfoTmpl, i.getInfo))
		mux.HandleFunc("/memory", render(MemoryTmpl, getMemory))

		// Internal debugging helpers.
		mux.HandleFunc("/gc", func(w http.ResponseWriter, r *http.Request) {
			runtime.GC()
			runtime.GC()
			runtime.GC()
			http.Redirect(w, r, "/memory", http.StatusTemporaryRedirect)
		})
		mux.HandleFunc("/_makeabug", func(w http.ResponseWriter, r *http.Request) {
			bug.Report("bug here")
			http.Error(w, "made a bug", http.StatusOK)
		})

		err := http.Serve(listener, mux) // always non-nil
		event.Error(ctx, "Debug server failed", err)
	}()
	return i.listenedDebugAddress, nil
}

func (i *Instance) DebugAddress() string {
	i.serveMu.Lock()
	defer i.serveMu.Unlock()
	return i.debugAddress
}

func (i *Instance) ListenedDebugAddress() string {
	i.serveMu.Lock()
	defer i.serveMu.Unlock()
	return i.listenedDebugAddress
}

func makeGlobalExporter(stderr io.Writer) event.Exporter {
	var (
		pMu sync.Mutex
		p   export.Printer
	)
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		i := GetInstance(ctx)

		if event.IsLog(ev) {
			// Don't log context cancellation errors.
			if err := keys.Err.Get(ev); errors.Is(err, context.Canceled) {
				return ctx
			}
			// Make sure any log messages without an instance go to stderr.
			if i == nil {
				pMu.Lock()
				p.WriteEvent(stderr, ev, lm)
				pMu.Unlock()
			}
			level := log.LabeledLevel(lm)
			// Exclude trace logs from LSP logs.
			if level < log.Trace {
				ctx = protocol.LogEvent(ctx, ev, lm, messageType(level))
			}
		}
		if i == nil {
			return ctx
		}
		return i.exporter(ctx, ev, lm)
	}
}

func messageType(l log.Level) protocol.MessageType {
	switch l {
	case log.Error:
		return protocol.Error
	case log.Warning:
		return protocol.Warning
	case log.Debug:
		return protocol.Log
	}
	return protocol.Info
}

func makeInstanceExporter(i *Instance) event.Exporter {
	exporter := func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		if i.prometheus != nil {
			ctx = i.prometheus.ProcessEvent(ctx, ev, lm)
		}
		if i.rpcs != nil {
			ctx = i.rpcs.ProcessEvent(ctx, ev, lm)
		}
		if i.traces != nil {
			ctx = i.traces.ProcessEvent(ctx, ev, lm)
		}
		if i.otel != nil {
			ctx = i.otel.ProcessEvent(ctx, ev, lm)
		}
		if event.IsLog(ev) {
			if s := cache.KeyCreateSession.Get(ev); s != nil {
				i.State.addClient(s)
			}
			if sid := label1.NewServer.Get(ev); sid != "" {
				i.State.updateServer(&Server{
					ID:           sid,
					Logfile:      label1.Logfile.Get(ev),
					DebugAddress: label1.DebugAddress.Get(ev),
					GoplsPath:    label1.GoplsPath.Get(ev),
					ClientID:     label1.ClientID.Get(ev),
				})
			}
			if s := cache.KeyShutdownSession.Get(ev); s != nil {
				i.State.dropClient(s)
			}
			if sid := label1.EndServer.Get(ev); sid != "" {
				i.State.dropServer(sid)
			}
			if s := cache.KeyUpdateSession.Get(ev); s != nil {
				if c := i.State.Client(s.ID()); c != nil {
					c.DebugAddress = label1.DebugAddress.Get(ev)
					c.Logfile = label1.Logfile.Get(ev)
					c.ServerID = label1.ServerID.Get(ev)
					c.GoplsPath = label1.GoplsPath.Get(ev)
				}
			}
		}
		return ctx
	}
	// StdTrace must be above export.Spans below (by convention, export
	// middleware applies its wrapped exporter last).
	exporter = StdTrace(exporter)
	metrics := metric.Config{}
	registerMetrics(&metrics)
	exporter = metrics.Exporter(exporter)
	exporter = export.Spans(exporter)
	exporter = export.Labels(exporter)
	return exporter
}

type dataFunc func(*http.Request) any

func render(tmpl *template.Template, fun dataFunc) func(http.ResponseWriter, *http.Request) {
	return func(w http.ResponseWriter, r *http.Request) {
		var data any
		if fun != nil {
			data = fun(r)
		}
		if err := tmpl.Execute(w, data); err != nil {
			event.Error(context.Background(), "", err)
			http.Error(w, err.Error(), http.StatusInternalServerError)
		}
	}
}

func commas(s string) string {
	for i := len(s); i > 3; {
		i -= 3
		s = s[:i] + "," + s[i:]
	}
	return s
}

func fuint64(v uint64) string {
	return commas(strconv.FormatUint(v, 10))
}

func fuint32(v uint32) string {
	return commas(strconv.FormatUint(uint64(v), 10))
}

func fcontent(v []byte) string {
	return string(v)
}

var BaseTemplate = template.Must(template.New("").Parse(`
<html>
<head>
<title>{{template "title" .}}</title>
<style>
.profile-name{
	display:inline-block;
	width:6rem;
}
td.value {
	text-align: right;
}
ul.spans {
	font-family: monospace;
	font-size:   85%;
}
body {
	font-family: sans-serif;
	font-size: 1rem;
	line-height: normal;
}
</style>
{{block "head" .}}{{end}}
</head>
<body>
<a href="/">Main</a>
<a href="/info">Info</a>
<a href="/memory">Memory</a>
<a href="/debug/pprof">Profiling</a>
<a href="/metrics">Metrics</a>
<a href="/rpc">RPC</a>
<a href="/trace">Trace</a>
<a href="/flightrecorder">Flight recorder</a>
<a href="/analysis">Analysis</a>
<hr>
<h1>{{template "title" .}}</h1>
{{block "body" .}}
Unknown page
{{end}}
</body>
</html>

{{define "cachelink"}}<a href="/cache/{{.}}">Cache {{.}}</a>{{end}}
{{define "clientlink"}}<a href="/client/{{.}}">Client {{.}}</a>{{end}}
{{define "serverlink"}}<a href="/server/{{.}}">Server {{.}}</a>{{end}}
{{define "sessionlink"}}<a href="/session/{{.}}">Session {{.}}</a>{{end}}
`)).Funcs(template.FuncMap{
	"fuint64":  fuint64,
	"fuint32":  fuint32,
	"fcontent": fcontent,
	"localAddress": func(s string) string {
		// Try to translate loopback addresses to localhost, both for cosmetics and
		// because unspecified ipv6 addresses can break links on Windows.
		//
		// TODO(rfindley): In the future, it would be better not to assume the
		// server is running on localhost, and instead construct this address using
		// the remote host.
		host, port, err := net.SplitHostPort(s)
		if err != nil {
			return s
		}
		ip := net.ParseIP(host)
		if ip == nil {
			return s
		}
		if ip.IsLoopback() || ip.IsUnspecified() {
			return "localhost:" + port
		}
		return s
	},
	// TODO(rfindley): re-enable option inspection.
	// "options": func(s *cache.Session) []sessionOption {
	// 	return showOptions(s.Options())
	// },
})

var MainTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Gopls server information{{end}}
{{define "body"}}
<h2>Caches</h2>
<ul>{{range .State.Caches}}<li>{{template "cachelink" .ID}}</li>{{end}}</ul>
<h2>Sessions</h2>
<ul>{{range .State.Sessions}}<li>{{template "sessionlink" .ID}} from {{template "cachelink" .Cache.ID}}</li>{{end}}</ul>
<h2>Clients</h2>
<ul>{{range .State.Clients}}<li>{{template "clientlink" .Session.ID}}</li>{{end}}</ul>
<h2>Servers</h2>
<ul>{{range .State.Servers}}<li>{{template "serverlink" .ID}}</li>{{end}}</ul>
<h2>Bug reports</h2>
<dl>{{range .State.Bugs}}<dt>{{.Key}}</dt><dd>{{.Description}}</dd>{{end}}</dl>
{{end}}
`))

var InfoTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Gopls version information{{end}}
{{define "body"}}
{{.}}
{{end}}
`))

var MemoryTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Gopls memory usage{{end}}
{{define "head"}}<meta http-equiv="refresh" content="5">{{end}}
{{define "body"}}
<form action="/gc"><input type="submit" value="Run garbage collector"/></form>
<h2>Stats</h2>
<table>
<tr><td class="label">Allocated bytes</td><td class="value">{{fuint64 .HeapAlloc}}</td></tr>
<tr><td class="label">Total allocated bytes</td><td class="value">{{fuint64 .TotalAlloc}}</td></tr>
<tr><td class="label">System bytes</td><td class="value">{{fuint64 .Sys}}</td></tr>
<tr><td class="label">Heap system bytes</td><td class="value">{{fuint64 .HeapSys}}</td></tr>
<tr><td class="label">Malloc calls</td><td class="value">{{fuint64 .Mallocs}}</td></tr>
<tr><td class="label">Frees</td><td class="value">{{fuint64 .Frees}}</td></tr>
<tr><td class="label">Idle heap bytes</td><td class="value">{{fuint64 .HeapIdle}}</td></tr>
<tr><td class="label">In use bytes</td><td class="value">{{fuint64 .HeapInuse}}</td></tr>
<tr><td class="label">Released to system bytes</td><td class="value">{{fuint64 .HeapReleased}}</td></tr>
<tr><td class="label">Heap object count</td><td class="value">{{fuint64 .HeapObjects}}</td></tr>
<tr><td class="label">Stack in use bytes</td><td class="value">{{fuint64 .StackInuse}}</td></tr>
<tr><td class="label">Stack from system bytes</td><td class="value">{{fuint64 .StackSys}}</td></tr>
<tr><td class="label">Bucket hash bytes</td><td class="value">{{fuint64 .BuckHashSys}}</td></tr>
<tr><td class="label">GC metadata bytes</td><td class="value">{{fuint64 .GCSys}}</td></tr>
<tr><td class="label">Off heap bytes</td><td class="value">{{fuint64 .OtherSys}}</td></tr>
</table>
<h2>By size</h2>
<table>
<tr><th>Size</th><th>Mallocs</th><th>Frees</th></tr>
{{range .BySize}}<tr><td class="value">{{fuint32 .Size}}</td><td class="value">{{fuint64 .Mallocs}}</td><td class="value">{{fuint64 .Frees}}</td></tr>{{end}}
</table>
{{end}}
`))

var DebugTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}GoPls Debug pages{{end}}
{{define "body"}}
<a href="/debug/pprof">Profiling</a>
{{end}}
`))

var CacheTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Cache {{.ID}}{{end}}
{{define "body"}}
<h2>memoize.Store entries</h2>
<ul>{{range $k,$v := .MemStats}}<li>{{$k}} - {{$v}}</li>{{end}}</ul>
<h2>File stats</h2>
<p>
{{- $stats := .FileStats -}}
Total: <b>{{$stats.Total}}</b><br>
Largest: <b>{{$stats.Largest}}</b><br>
Errors: <b>{{$stats.Errs}}</b><br>
</p>
{{end}}
`))

var AnalysisTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Analysis{{end}}
{{define "body"}}
<h2>Analyzer.Run times</h2>
<ul>{{range .AnalyzerRunTimes}}<li>{{.Duration}} {{.Label}}</li>{{end}}</ul>
{{end}}
`))

var ClientTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Client {{.Session.ID}}{{end}}
{{define "body"}}
Using session: <b>{{template "sessionlink" .Session.ID}}</b><br>
{{if .DebugAddress}}Debug this client at: <a href="http://{{localAddress .DebugAddress}}">{{localAddress .DebugAddress}}</a><br>{{end}}
Logfile: {{.Logfile}}<br>
Gopls Path: {{.GoplsPath}}<br>
{{end}}
`))

var ServerTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Server {{.ID}}{{end}}
{{define "body"}}
{{if .DebugAddress}}Debug this server at: <a href="http://{{localAddress .DebugAddress}}">{{localAddress .DebugAddress}}</a><br>{{end}}
Logfile: {{.Logfile}}<br>
Gopls Path: {{.GoplsPath}}<br>
{{end}}
`))

var SessionTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Session {{.ID}}{{end}}
{{define "body"}}
From: <b>{{template "cachelink" .Cache.ID}}</b><br>
{{- $session := . -}}

<h2>Views</h2>
<ul>{{range .Views}}
{{- $envOverlay := .EnvOverlay -}}
<li>ID: <b>{{.ID}}</b><br>
Type: <b>{{.Type}}</b><br>
Root: <b>{{.Root}}</b><br>
{{- if $envOverlay}}
Env overlay: <b>{{$envOverlay}})</b><br>
{{end -}}
Folder.Name: <b>{{.Folder.Name}}</b><br>
Folder.Dir: <b>{{.Folder.Dir}}</b><br/>
<a href="/metadata/{{$session.ID}}/{{.ID}}">Latest metadata</a><br/>

Settings:<br/>
<ul>
{{range .Folder.Options.Debug}}<li>{{.}}</li>
{{end}}
</ul>
{{end}}</ul>

<h2>Overlays</h2>
{{$session := .}}
<ul>{{range .Overlays}}
<li>
<a href="/file/{{$session.ID}}/{{.Identity.Hash}}">{{.Identity.URI}}</a>
</li>{{end}}</ul>
{{end}}
`))

// For /file endpoint; operand is [FileWithKind].
var FileTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Overlay {{.Identity.Hash}}{{end}}
{{define "body"}}
{{with .}}
	URI: <b>{{.URI}}</b><br>
	Identifier: <b>{{.Identity.Hash}}</b><br>
	Version: <b>{{.Version}}</b><br>
	Kind: <b>{{.Kind}}</b><br>
{{end}}
<h3>Contents</h3>
<pre>{{fcontent .Content}}</pre>
{{end}}
`))

// For /metadata endpoint; operand is [*MetadataInfo].
var MetadataTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Metadata graph{{end}}
{{define "body"}}

<p><a href='#hdr-Files'>↓ Index by file</a></p>

<h3>Packages ({{len .Graph.Packages}})</h3>
<ul>
{{range $id, $pkg := .Graph.Packages}}
<li id='{{$id}}'><b>{{$id}}</b>
{{with $pkg}}
<ul>
 <li>Name: {{.Name}}</li>
 <li>PkgPath: {{printf "%q" .PkgPath}}</li>
 {{if .Module}}<li>Module: {{printf "%#v" .Module}}</li>{{end}}
 <li><a href="/package/{{$.SessionID}}/{{$.ViewID}}/{{$id}}">Type information</a></li>
 {{if .ForTest}}<li>ForTest: {{.ForTest}}</li>{{end}}
 {{if .Standalone}}<li>Standalone</li>{{end}}
 {{if .Errors}}<li>Errors: {{.Errors}}</li>{{end}}
 {{if .DepsErrors}}<li>DepsErrors: {{.DepsErrors}}</li>{{end}}
 <li>LoadDir: {{.LoadDir}}</li>
 <li>DepsByImpPath
  <ul>
   {{range $path, $id := .DepsByImpPath}}
    <li>{{if $id}}<a href='#{{$id}}'>{{printf "%q" $path}}</a>{{else}}⚠️ {{printf "%q" $path}} missing{{end}}</li>
   {{end}}
  </ul>
 </li>
 {{if .GoFiles}}<li>GoFiles: <ul>{{range .GoFiles}}<li>{{.}}</li>{{end}}</ul></li>{{end}}
 {{if .CompiledGoFiles}}<li>CompiledGoFiles: <ul>{{range .CompiledGoFiles}}<li>{{.}}</li>{{end}}</ul></li>{{end}}
 {{if .IgnoredFiles}}<li>IgnoredFiles: <ul>{{range .IgnoredFiles}}<li>{{.}}</li>{{end}}</ul></li>{{end}}
 {{if .OtherFiles}}<li>OtherFiles: <ul>{{range .OtherFiles}}<li>{{.}}</li>{{end}}</ul></li>{{end}}
 <!-- skip DepsByPkgPath, ImportedBy (redundant indexes) -->
</ul>
{{end}}
</li>
{{end}}
</ul>

<h3 id='hdr-Files'>Files</h3>
<ul>
{{range $uri, $pkgs := .Graph.ForFile}}<li>{{$uri}} →{{range $pkgs}} <a href='#{{.ID}}'>{{.ID}}</a>{{end}}</li>{{end}}
</ul>

{{end}}
`))

// For /package endpoint; operand is [*PackageInfo].
var PackageTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Package {{.Package.Metadata.ID}}{{end}}
{{define "body"}}

<ul>
<li><a href="/metadata/{{.SessionID}}/{{.ViewID}}#{{.Package.Metadata.ID}}">Metadata</a></li>
</ul>

<h2>Diagnostics for syntax and type (but not analysis) errors</h2>
<ul>
 {{range $url, $diags := .Diagnostics}}
 <li>{{$url}}
  <ul>
  {{range $diag := $diags}}
  <li>{{$diag.Range}}: [{{$diag.Severity}}] {{$diag.Message}}<br/>
  <ul>
    <li>code {{$diag.Code}}</li>
    <li>code href {{$diag.CodeHref}}</li>
    <li>source {{$diag.Source}}</li>
    <li>tags {{$diag.Tags}}</li>
    <li>related {{$diag.Related}}</li> {{/*TODO: improve*/}}
    <li>bundled fixes {{$diag.BundledFixes}}</li> {{/*TODO: improve*/}}
    <li>fixes {{$diag.SuggestedFixes}}</li> {{/*TODO: improve*/}}
  </ul>
  {{end}}
 </ul>
 {{end}}
</ul>

{{end}}
{{/*
TODO:
 - link to godoc (tricky: in server package)
 - show Object inventory of types.Package.Scope
 - show index info (xrefs, methodsets, tests)
 - call DiagnoseFile on each file?
*/}}
`))


================================================
FILE: gopls/internal/debug/template_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug_test

// Provide 'static type checking' of the templates. This guards against changes in various
// gopls datastructures causing template execution to fail. The checking is done by
// the github.com/jba/templatecheck package. Before that is run, the test checks that
// its list of templates and their arguments corresponds to the arguments in
// calls to render(). The test assumes that all uses of templates are done through render().

import (
	"go/ast"
	"html/template"
	"os"
	"runtime"
	"strings"
	"testing"

	"github.com/jba/templatecheck"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/internal/testenv"
)

var templates = map[string]struct {
	tmpl *template.Template
	data any // a value of the needed type
}{
	"MainTmpl":     {debug.MainTmpl, &debug.Instance{}},
	"DebugTmpl":    {debug.DebugTmpl, nil},
	"RPCTmpl":      {debug.RPCTmpl, &debug.Rpcs{}},
	"TraceTmpl":    {debug.TraceTmpl, debug.TraceResults{}},
	"CacheTmpl":    {debug.CacheTmpl, &cache.Cache{}},
	"SessionTmpl":  {debug.SessionTmpl, &cache.Session{}},
	"ClientTmpl":   {debug.ClientTmpl, &debug.Client{}},
	"ServerTmpl":   {debug.ServerTmpl, &debug.Server{}},
	"FileTmpl":     {debug.FileTmpl, *new(debug.FileWithKind)},
	"MetadataTmpl": {debug.MetadataTmpl, new(debug.MetadataInfo)},
	"PackageTmpl":  {debug.PackageTmpl, new(debug.PackageInfo)},
	"InfoTmpl":     {debug.InfoTmpl, "something"},
	"MemoryTmpl":   {debug.MemoryTmpl, runtime.MemStats{}},
	"AnalysisTmpl": {debug.AnalysisTmpl, new(debug.State).Analysis()},
}

func TestTemplates(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.NeedsLocalXTools(t)

	cfg := &packages.Config{
		Mode: packages.NeedTypes | packages.NeedSyntax | packages.NeedTypesInfo,
	}
	cfg.Env = os.Environ()
	cfg.Env = append(cfg.Env,
		"GOPACKAGESDRIVER=off",
		"GOWORK=off", // necessary for -mod=mod below
		"GOFLAGS=-mod=mod",
	)

	pkgs, err := packages.Load(cfg, "golang.org/x/tools/gopls/internal/debug")
	if err != nil {
		t.Fatal(err)
	}
	if len(pkgs) != 1 {
		t.Fatalf("expected a single package, but got %d", len(pkgs))
	}
	p := pkgs[0]
	if len(p.Errors) != 0 {
		t.Fatalf("compiler error, e.g. %v", p.Errors[0])
	}
	// find the calls to render in serve.go
	tree := treeOf(p, "serve.go")
	if tree == nil {
		t.Fatalf("found no syntax tree for %s", "serve.go")
	}
	renders := callsOf(tree, "render")
	if len(renders) == 0 {
		t.Fatalf("found no calls to render")
	}
	var found = make(map[string]bool)
	for _, r := range renders {
		if len(r.Args) != 2 {
			// template, func
			t.Fatalf("got %d args, expected 2", len(r.Args))
		}
		t0, ok := p.TypesInfo.Types[r.Args[0]]
		if !ok || !t0.IsValue() || t0.Type.String() != "*html/template.Template" {
			t.Fatalf("no type info for template")
		}
		if id, ok := r.Args[0].(*ast.Ident); !ok {
			t.Errorf("expected *ast.Ident, got %T", r.Args[0])
		} else {
			found[id.Name] = true
		}
	}
	// make sure found and templates have the same templates
	for k := range found {
		if _, ok := templates[k]; !ok {
			t.Errorf("code has template %s, but test does not", k)
		}
	}
	for k := range templates {
		if _, ok := found[k]; !ok {
			t.Errorf("test has template %s, code does not", k)
		}
	}
	// now check all the known templates, in alphabetic order, for determinacy
	for k, v := range moremaps.Sorted(templates) {
		// the FuncMap is an annoyance; should not be necessary
		if err := templatecheck.CheckHTML(v.tmpl, v.data); err != nil {
			t.Errorf("%s: %v", k, err)
			continue
		}
		t.Logf("%s ok", k)
	}
}

func callsOf(tree *ast.File, name string) []*ast.CallExpr {
	var ans []*ast.CallExpr
	f := func(n ast.Node) bool {
		x, ok := n.(*ast.CallExpr)
		if !ok {
			return true
		}
		if y, ok := x.Fun.(*ast.Ident); ok {
			if y.Name == name {
				ans = append(ans, x)
			}
		}
		return true
	}
	ast.Inspect(tree, f)
	return ans
}

func treeOf(p *packages.Package, fname string) *ast.File {
	for _, tree := range p.Syntax {
		loc := tree.Package
		pos := p.Fset.PositionFor(loc, false)
		if strings.HasSuffix(pos.Filename, fname) {
			return tree
		}
	}
	return nil
}


================================================
FILE: gopls/internal/debug/trace.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug

import (
	"bytes"
	"context"
	"fmt"
	"html/template"
	"net/http"
	"runtime/trace"
	"slices"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/label"
)

// TraceTmpl extends BaseTemplate and renders a TraceResults, e.g. from getData().
var TraceTmpl = template.Must(template.Must(BaseTemplate.Clone()).Parse(`
{{define "title"}}Trace Information{{end}}
{{define "body"}}
	{{range .Traces}}<a href="/trace/{{.Name}}">{{.Name}}</a> last: {{.Last.Duration}}, longest: {{.Longest.Duration}}<br>{{end}}
	{{if .Selected}}
		<H2>{{.Selected.Name}}</H2>
		{{if .Selected.Last}}<H3>Last</H3><ul class='spans'>{{template "completeSpan" .Selected.Last}}</ul>{{end}}
		{{if .Selected.Longest}}<H3>Longest</H3><ul class='spans'>{{template "completeSpan" .Selected.Longest}}</ul>{{end}}
	{{end}}

        <H2>Recent spans (oldest first)</H2>
        <p>
        A finite number of recent span start/end times are shown below.
        The nesting represents the children of a parent span (and the log events within a span).
        A span may appear twice: chronologically at toplevel, and nested within its parent.
        </p>
	<ul class='spans'>{{range .Recent}}{{template "spanStartEnd" .}}{{end}}</ul>
{{end}}
{{define "spanStartEnd"}}
	{{if .Start}}
		<li>{{.Span.Header .Start}}</li>
	{{else}}
		{{template "completeSpan" .Span}}
	{{end}}
{{end}}
{{define "completeSpan"}}
	<li>{{.Header false}}</li>
	{{if .Events}}<ul>{{range .Events}}<li>{{.Header}}</li>{{end}}</ul>{{end}}
	{{if .ChildStartEnd}}<ul>{{range .ChildStartEnd}}{{template "spanStartEnd" .}}{{end}}</ul>{{end}}
{{end}}
`))

type traces struct {
	mu              sync.Mutex
	sets            map[string]*traceSet
	unfinished      map[export.SpanContext]*traceSpan
	recent          []spanStartEnd
	recentEvictions int
}

// A spanStartEnd records the start or end of a span.
// If Start, the span may be unfinished, so some fields (e.g. Finish)
// may be unset and others (e.g. Events) may be being actively populated.
type spanStartEnd struct {
	Start bool
	Span  *traceSpan
}

func (ev spanStartEnd) Time() time.Time {
	if ev.Start {
		return ev.Span.Start
	} else {
		return ev.Span.Finish
	}
}

// A TraceResults is the subject for the /trace HTML template.
type TraceResults struct { // exported for testing
	Traces   []*traceSet
	Selected *traceSet
	Recent   []spanStartEnd
}

// A traceSet holds two representative spans of a given span name.
type traceSet struct {
	Name    string
	Last    *traceSpan
	Longest *traceSpan
}

// A traceSpan holds information about a single span.
type traceSpan struct {
	TraceID       export.TraceID
	SpanID        export.SpanID
	ParentID      export.SpanID
	Name          string
	Start         time.Time
	Finish        time.Time     // set at end
	Duration      time.Duration // set at end
	Tags          string
	Events        []traceEvent   // set at end
	ChildStartEnd []spanStartEnd // populated while active

	parent *traceSpan
}

const timeFormat = "15:04:05.000"

// Header renders the time, name, tags, and (if !start),
// duration of a span start or end event.
func (span *traceSpan) Header(start bool) string {
	if start {
		return fmt.Sprintf("%s start %s %s",
			span.Start.Format(timeFormat), span.Name, span.Tags)
	} else {
		return fmt.Sprintf("%s end %s (+%s) %s",
			span.Finish.Format(timeFormat), span.Name, span.Duration, span.Tags)
	}
}

type traceEvent struct {
	Time   time.Time
	Offset time.Duration // relative to start of span
	Tags   string
}

func (ev traceEvent) Header() string {
	return fmt.Sprintf("%s event (+%s) %s", ev.Time.Format(timeFormat), ev.Offset, ev.Tags)
}

func StdTrace(exporter event.Exporter) event.Exporter {
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		span := export.GetSpan(ctx)
		if span == nil {
			return exporter(ctx, ev, lm)
		}
		switch {
		case event.IsStart(ev):
			if span.ParentID.IsValid() {
				region := trace.StartRegion(ctx, span.Name)
				ctx = context.WithValue(ctx, traceKey, region)
			} else {
				var task *trace.Task
				ctx, task = trace.NewTask(ctx, span.Name)
				ctx = context.WithValue(ctx, traceKey, task)
			}
			// Log the start event as it may contain useful labels.
			msg := formatEvent(ev, lm)
			trace.Log(ctx, "start", msg)
		case event.IsLog(ev):
			category := ""
			if event.IsError(ev) {
				category = "error"
			}
			msg := formatEvent(ev, lm)
			trace.Log(ctx, category, msg)
		case event.IsEnd(ev):
			if v := ctx.Value(traceKey); v != nil {
				v.(interface{ End() }).End()
			}
		}
		return exporter(ctx, ev, lm)
	}
}

func formatEvent(ev core.Event, lm label.Map) string {
	buf := &bytes.Buffer{}
	p := export.Printer{}
	p.WriteEvent(buf, ev, lm)
	return buf.String()
}

func (t *traces) ProcessEvent(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	span := export.GetSpan(ctx)
	if span == nil {
		return ctx
	}

	switch {
	case event.IsStart(ev):
		// Just starting: add it to the unfinished map.
		// Allocate before the critical section.
		td := &traceSpan{
			TraceID:  span.ID.TraceID,
			SpanID:   span.ID.SpanID,
			ParentID: span.ParentID,
			Name:     span.Name,
			Start:    span.Start().At(),
			Tags:     renderLabels(span.Start()),
		}

		t.mu.Lock()
		defer t.mu.Unlock()

		t.addRecentLocked(td, true) // add start event

		if t.sets == nil {
			t.sets = make(map[string]*traceSet)
			t.unfinished = make(map[export.SpanContext]*traceSpan)
		}
		t.unfinished[span.ID] = td

		// Wire up parents if we have them.
		if span.ParentID.IsValid() {
			parentID := export.SpanContext{TraceID: span.ID.TraceID, SpanID: span.ParentID}
			if parent, ok := t.unfinished[parentID]; ok {
				td.parent = parent
				parent.ChildStartEnd = append(parent.ChildStartEnd, spanStartEnd{true, td})
			}
		}

	case event.IsEnd(ev):
		// Finishing: must be already in the map.
		// Allocate events before the critical section.
		events := span.Events()
		tdEvents := make([]traceEvent, len(events))
		for i, event := range events {
			tdEvents[i] = traceEvent{
				Time: event.At(),
				Tags: renderLabels(event),
			}
		}

		t.mu.Lock()
		defer t.mu.Unlock()
		td, found := t.unfinished[span.ID]
		if !found {
			return ctx // if this happens we are in a bad place
		}
		delete(t.unfinished, span.ID)
		td.Finish = span.Finish().At()
		td.Duration = span.Finish().At().Sub(span.Start().At())
		td.Events = tdEvents
		t.addRecentLocked(td, false) // add end event

		set, ok := t.sets[span.Name]
		if !ok {
			set = &traceSet{Name: span.Name}
			t.sets[span.Name] = set
		}
		set.Last = td
		if set.Longest == nil || set.Last.Duration > set.Longest.Duration {
			set.Longest = set.Last
		}
		if td.parent != nil {
			td.parent.ChildStartEnd = append(td.parent.ChildStartEnd, spanStartEnd{false, td})
		} else {
			fillOffsets(td, td.Start)
		}
	}
	return ctx
}

// addRecentLocked appends a start or end event to the "recent" log,
// evicting an old entry if necessary.
func (t *traces) addRecentLocked(span *traceSpan, start bool) {
	t.recent = append(t.recent, spanStartEnd{Start: start, Span: span})

	const maxRecent = 100 // number of log entries before eviction
	for len(t.recent) > maxRecent {
		t.recent[0] = spanStartEnd{} // aid GC
		t.recent = t.recent[1:]
		t.recentEvictions++

		// Using a slice as a FIFO queue leads to unbounded growth
		// as Go's GC cannot collect the ever-growing unused prefix.
		// So, compact it periodically.
		if t.recentEvictions%maxRecent == 0 {
			t.recent = slices.Clone(t.recent)
		}
	}
}

// getData returns the TraceResults rendered by TraceTmpl for the /trace[/name] endpoint.
func (t *traces) getData(req *http.Request) any {
	// TODO(adonovan): the HTTP request doesn't acquire the mutex
	// for t or for each span! Audit and fix.

	// Sort last/longest sets by name.
	traces := make([]*traceSet, 0, len(t.sets))
	for _, set := range t.sets {
		traces = append(traces, set)
	}
	sort.Slice(traces, func(i, j int) bool {
		return traces[i].Name < traces[j].Name
	})

	return TraceResults{
		Traces:   traces,
		Selected: t.sets[strings.TrimPrefix(req.URL.Path, "/trace/")], // may be nil
		Recent:   t.recent,
	}
}

func fillOffsets(td *traceSpan, start time.Time) {
	for i := range td.Events {
		td.Events[i].Offset = td.Events[i].Time.Sub(start)
	}
	for _, child := range td.ChildStartEnd {
		if !child.Start {
			fillOffsets(child.Span, start)
		}
	}
}

func renderLabels(labels label.List) string {
	buf := &bytes.Buffer{}
	for index := 0; labels.Valid(index); index++ {
		// The 'start' label duplicates the span name, so discard it.
		if l := labels.Label(index); l.Valid() && l.Key().Name() != "start" {
			fmt.Fprintf(buf, "%v ", l)
		}
	}
	return buf.String()
}


================================================
FILE: gopls/internal/doc/api.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run ./generate

// The doc package provides JSON metadata that documents gopls' public
// interfaces.
package doc

import _ "embed"

// JSON is a JSON encoding of value of type API.
// The 'gopls api-json' command prints it.
//
//go:embed api.json
var JSON string

// API is a JSON-encodable representation of gopls' public interfaces.
//
// TODO(adonovan): document these data types.
type API struct {
	Options   map[string][]*Option
	Lenses    []*Lens
	Analyzers []*Analyzer
	Hints     []*Hint
}

type Option struct {
	Name               string
	Type               string // T = bool | string | int | enum | any | []T | map[T]T | time.Duration
	Doc                string
	EnumKeys           EnumKeys
	EnumValues         []EnumValue
	Default            string
	Status             string
	Hierarchy          string
	DeprecationMessage string
}

type EnumKeys struct {
	ValueType string
	Keys      []EnumKey
}

type EnumKey struct {
	Name    string // in JSON syntax (quoted)
	Doc     string
	Default string
	Status  string // = "" | "advanced" | "experimental" | "deprecated"
}

type EnumValue struct {
	Value  string // in JSON syntax (quoted)
	Doc    string // doc comment; always starts with `Value`
	Status string // = "" | "advanced" | "experimental" | "deprecated"
}

type Lens struct {
	FileType string // e.g. "Go", "go.mod"
	Lens     string
	Title    string
	Doc      string
	Default  bool
	Status   string // = "" | "advanced" | "experimental" | "deprecated"
}

type Analyzer struct {
	Name    string
	Doc     string // from analysis.Analyzer.Doc ("title: summary\ndescription"; go/doc/comment, not Markdown)
	URL     string
	Default bool
}

type Hint struct {
	Name    string
	Doc     string
	Default bool
	Status  string // = "" | "advanced" | "experimental" | "deprecated"
}


================================================
FILE: gopls/internal/doc/api.json
================================================
{
	"Options": {
		"User": [
			{
				"Name": "buildFlags",
				"Type": "[]string",
				"Doc": "buildFlags is the set of flags passed on to the build system when invoked.\nIt is applied to queries like `go list`, which is used when discovering files.\nThe most common use is to set `-tags`.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "[]",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "env",
				"Type": "map[string]string",
				"Doc": "env adds environment variables to external commands run by `gopls`, most notably `go list`.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "{}",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "directoryFilters",
				"Type": "[]string",
				"Doc": "directoryFilters can be used to exclude unwanted directories from the\nworkspace. By default, all directories are included. Filters are an\noperator, `+` to include and `-` to exclude, followed by a path prefix\nrelative to the workspace folder. They are evaluated in order, and\nthe last filter that applies to a path controls whether it is included.\nThe path prefix can be empty, so an initial `-` excludes everything.\n\nDirectoryFilters also supports the `**` operator to match 0 or more directories.\n\nExamples:\n\nExclude node_modules at current depth: `-node_modules`\n\nExclude node_modules at any depth: `-**/node_modules`\n\nInclude only project_a: `-` (exclude everything), `+project_a`\n\nInclude only project_a, but not node_modules inside it: `-`, `+project_a`, `-project_a/node_modules`\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "[\"-**/node_modules\"]",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "templateExtensions",
				"Type": "[]string",
				"Doc": "templateExtensions gives the extensions of file names that are treated\nas template files. (The extension\nis the part of the file name after the final dot.)\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "[]",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "memoryMode",
				"Type": "string",
				"Doc": "obsolete, no effect\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "\"\"",
				"Status": "experimental",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "expandWorkspaceToModule",
				"Type": "bool",
				"Doc": "expandWorkspaceToModule determines which packages are considered\n\"workspace packages\" when the workspace is using modules.\n\nWorkspace packages affect the scope of workspace-wide operations. Notably,\ngopls diagnoses all packages considered to be part of the workspace after\nevery keystroke, so by setting \"ExpandWorkspaceToModule\" to false, and\nopening a nested workspace directory, you can reduce the amount of work\ngopls has to do to keep your workspace up to date.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "true",
				"Status": "experimental",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "standaloneTags",
				"Type": "[]string",
				"Doc": "standaloneTags specifies a set of build constraints that identify\nindividual Go source files that make up the entire main package of an\nexecutable.\n\nA common example of standalone main files is the convention of using the\ndirective `//go:build ignore` to denote files that are not intended to be\nincluded in any package, for example because they are invoked directly by\nthe developer using `go run`.\n\nGopls considers a file to be a standalone main file if and only if it has\npackage name \"main\" and has a build directive of the exact form\n\"//go:build tag\" or \"// +build tag\", where tag is among the list of tags\nconfigured by this setting. Notably, if the build constraint is more\ncomplicated than a simple tag (such as the composite constraint\n`//go:build tag \u0026\u0026 go1.18`), the file is not considered to be a standalone\nmain file.\n\nThis setting is only supported when gopls is built with Go 1.16 or later.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "[\"ignore\"]",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "workspaceFiles",
				"Type": "[]string",
				"Doc": "workspaceFiles configures the set of globs that match files defining the\nlogical build of the current workspace. Any on-disk changes to any files\nmatching a glob specified here will trigger a reload of the workspace.\n\nThis setting need only be customized in environments with a custom\nGOPACKAGESDRIVER.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "[]",
				"Status": "",
				"Hierarchy": "build",
				"DeprecationMessage": ""
			},
			{
				"Name": "hoverKind",
				"Type": "enum",
				"Doc": "hoverKind controls the information that appears in the hover text.\nSingleLine is intended for use only by authors of editor plugins.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"FullDocumentation\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"NoDocumentation\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"SingleLine\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"Structured\"",
						"Doc": "`\"Structured\"` is a misguided experimental setting that returns a JSON\nhover format. This setting should not be used, as it will be removed in a\nfuture release of gopls.\n",
						"Status": ""
					},
					{
						"Value": "\"SynopsisDocumentation\"",
						"Doc": "",
						"Status": ""
					}
				],
				"Default": "\"FullDocumentation\"",
				"Status": "",
				"Hierarchy": "ui.documentation",
				"DeprecationMessage": ""
			},
			{
				"Name": "linkTarget",
				"Type": "string",
				"Doc": "linkTarget is the base URL for links to Go package\ndocumentation returned by LSP operations such as Hover and\nDocumentLinks and in the CodeDescription field of each\nDiagnostic.\n\nIt might be one of:\n\n* `\"godoc.org\"`\n* `\"pkg.go.dev\"`\n\nIf company chooses to use its own `godoc.org`, its address can be used as well.\n\nModules matching the GOPRIVATE environment variable will not have\ndocumentation links in hover.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "\"pkg.go.dev\"",
				"Status": "",
				"Hierarchy": "ui.documentation",
				"DeprecationMessage": ""
			},
			{
				"Name": "linksInHover",
				"Type": "enum",
				"Doc": "linksInHover controls the presence of documentation links in hover markdown.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "false",
						"Doc": "false: do not show links",
						"Status": ""
					},
					{
						"Value": "true",
						"Doc": "true: show links to the `linkTarget` domain",
						"Status": ""
					},
					{
						"Value": "\"gopls\"",
						"Doc": "`\"gopls\"`: show links to gopls' internal documentation viewer",
						"Status": ""
					}
				],
				"Default": "true",
				"Status": "",
				"Hierarchy": "ui.documentation",
				"DeprecationMessage": ""
			},
			{
				"Name": "usePlaceholders",
				"Type": "bool",
				"Doc": "placeholders enables placeholders for function parameters or struct\nfields in completion responses.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "",
				"Hierarchy": "ui.completion",
				"DeprecationMessage": ""
			},
			{
				"Name": "completionBudget",
				"Type": "time.Duration",
				"Doc": "completionBudget is the soft latency goal for completion requests. Most\nrequests finish in a couple milliseconds, but in some cases deep\ncompletions can take much longer. As we use up our budget we\ndynamically reduce the search scope to ensure we return timely\nresults. Zero means unlimited.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "\"100ms\"",
				"Status": "debug",
				"Hierarchy": "ui.completion",
				"DeprecationMessage": ""
			},
			{
				"Name": "matcher",
				"Type": "enum",
				"Doc": "matcher sets the algorithm that is used when calculating completion\ncandidates.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"CaseInsensitive\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"CaseSensitive\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"Fuzzy\"",
						"Doc": "",
						"Status": ""
					}
				],
				"Default": "\"Fuzzy\"",
				"Status": "advanced",
				"Hierarchy": "ui.completion",
				"DeprecationMessage": ""
			},
			{
				"Name": "experimentalPostfixCompletions",
				"Type": "bool",
				"Doc": "experimentalPostfixCompletions enables artificial method snippets\nsuch as \"someSlice.sort!\".\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "true",
				"Status": "experimental",
				"Hierarchy": "ui.completion",
				"DeprecationMessage": ""
			},
			{
				"Name": "completeFunctionCalls",
				"Type": "bool",
				"Doc": "completeFunctionCalls enables function call completion.\n\nWhen completing a statement, or when a function return type matches the\nexpected of the expression being completed, completion may suggest call\nexpressions (i.e. may include parentheses).\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "true",
				"Status": "",
				"Hierarchy": "ui.completion",
				"DeprecationMessage": ""
			},
			{
				"Name": "importShortcut",
				"Type": "enum",
				"Doc": "importShortcut specifies whether import statements should link to\ndocumentation or go to definitions.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"Both\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"Definition\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"Link\"",
						"Doc": "",
						"Status": ""
					}
				],
				"Default": "\"Both\"",
				"Status": "",
				"Hierarchy": "ui.navigation",
				"DeprecationMessage": ""
			},
			{
				"Name": "symbolMatcher",
				"Type": "enum",
				"Doc": "symbolMatcher sets the algorithm that is used when finding workspace symbols.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"CaseInsensitive\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"CaseSensitive\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"FastFuzzy\"",
						"Doc": "",
						"Status": ""
					},
					{
						"Value": "\"Fuzzy\"",
						"Doc": "",
						"Status": ""
					}
				],
				"Default": "\"FastFuzzy\"",
				"Status": "advanced",
				"Hierarchy": "ui.navigation",
				"DeprecationMessage": ""
			},
			{
				"Name": "symbolStyle",
				"Type": "enum",
				"Doc": "symbolStyle controls how symbols are qualified in symbol responses.\n\nExample Usage:\n\n```json5\n\"gopls\": {\n...\n  \"symbolStyle\": \"Dynamic\",\n...\n}\n```\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"Dynamic\"",
						"Doc": "`\"Dynamic\"` uses whichever qualifier results in the highest scoring\nmatch for the given symbol query. Here a \"qualifier\" is any \"/\" or \".\"\ndelimited suffix of the fully qualified symbol. i.e. \"to/pkg.Foo.Field\" or\njust \"Foo.Field\".\n",
						"Status": ""
					},
					{
						"Value": "\"Full\"",
						"Doc": "`\"Full\"` is fully qualified symbols, i.e.\n\"path/to/pkg.Foo.Field\".\n",
						"Status": ""
					},
					{
						"Value": "\"Package\"",
						"Doc": "`\"Package\"` is package qualified symbols i.e.\n\"pkg.Foo.Field\".\n",
						"Status": ""
					}
				],
				"Default": "\"Dynamic\"",
				"Status": "advanced",
				"Hierarchy": "ui.navigation",
				"DeprecationMessage": ""
			},
			{
				"Name": "symbolScope",
				"Type": "enum",
				"Doc": "symbolScope controls which packages are searched for workspace/symbol\nrequests. When the scope is \"workspace\", gopls searches only workspace\npackages. When the scope is \"all\", gopls searches all loaded packages,\nincluding dependencies and the standard library.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"all\"",
						"Doc": "`\"all\"` matches symbols in any loaded package, including\ndependencies.\n",
						"Status": ""
					},
					{
						"Value": "\"workspace\"",
						"Doc": "`\"workspace\"` matches symbols in workspace packages only.\n",
						"Status": ""
					}
				],
				"Default": "\"all\"",
				"Status": "",
				"Hierarchy": "ui.navigation",
				"DeprecationMessage": ""
			},
			{
				"Name": "analyses",
				"Type": "map[string]bool",
				"Doc": "analyses specify analyses that the user would like to enable or disable.\nA map of the names of analysis passes that should be enabled/disabled.\nA full list of analyzers that gopls uses can be found in\n[analyzers.md](https://github.com/golang/tools/blob/master/gopls/doc/analyzers.md).\n\nExample Usage:\n\n```json5\n...\n\"analyses\": {\n  \"unreachable\": false, // Disable the unreachable analyzer.\n  \"unusedvariable\": true  // Enable the unusedvariable analyzer.\n}\n...\n```\n",
				"EnumKeys": {
					"ValueType": "bool",
					"Keys": [
						{
							"Name": "\"QF1001\"",
							"Doc": "Apply De Morgan's law\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1002\"",
							"Doc": "Convert untagged switch to tagged switch\n\nAn untagged switch that compares a single variable against a series of\nvalues can be replaced with a tagged switch.\n\nBefore:\n\n    switch {\n    case x == 1 || x == 2, x == 3:\n        ...\n    case x == 4:\n        ...\n    default:\n        ...\n    }\n\nAfter:\n\n    switch x {\n    case 1, 2, 3:\n        ...\n    case 4:\n        ...\n    default:\n        ...\n    }\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"QF1003\"",
							"Doc": "Convert if/else-if chain to tagged switch\n\nA series of if/else-if checks comparing the same variable against\nvalues can be replaced with a tagged switch.\n\nBefore:\n\n    if x == 1 || x == 2 {\n        ...\n    } else if x == 3 {\n        ...\n    } else {\n        ...\n    }\n\nAfter:\n\n    switch x {\n    case 1, 2:\n        ...\n    case 3:\n        ...\n    default:\n        ...\n    }\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"QF1004\"",
							"Doc": "Use strings.ReplaceAll instead of strings.Replace with n == -1\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"QF1005\"",
							"Doc": "Expand call to math.Pow\n\nSome uses of math.Pow can be simplified to basic multiplication.\n\nBefore:\n\n    math.Pow(x, 2)\n\nAfter:\n\n    x * x\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1006\"",
							"Doc": "Lift if+break into loop condition\n\nBefore:\n\n    for {\n        if done {\n            break\n        }\n        ...\n    }\n\nAfter:\n\n    for !done {\n        ...\n    }\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1007\"",
							"Doc": "Merge conditional assignment into variable declaration\n\nBefore:\n\n    x := false\n    if someCondition {\n        x = true\n    }\n\nAfter:\n\n    x := someCondition\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1008\"",
							"Doc": "Omit embedded fields from selector expression\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1009\"",
							"Doc": "Use time.Time.Equal instead of == operator\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"QF1010\"",
							"Doc": "Convert slice of bytes to string when printing it\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"QF1011\"",
							"Doc": "Omit redundant type from variable declaration\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"QF1012\"",
							"Doc": "Use fmt.Fprintf(x, ...) instead of x.Write(fmt.Sprintf(...))\n\nAvailable since\n    2022.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1000\"",
							"Doc": "Use plain channel send or receive instead of single-case select\n\nSelect statements with a single case can be replaced with a simple\nsend or receive.\n\nBefore:\n\n    select {\n    case x := \u003c-ch:\n        fmt.Println(x)\n    }\n\nAfter:\n\n    x := \u003c-ch\n    fmt.Println(x)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1001\"",
							"Doc": "Replace for loop with call to copy\n\nUse copy() for copying elements from one slice to another. For\narrays of identical size, you can use simple assignment.\n\nBefore:\n\n    for i, x := range src {\n        dst[i] = x\n    }\n\nAfter:\n\n    copy(dst, src)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1002\"",
							"Doc": "Omit comparison with boolean constant\n\nBefore:\n\n    if x == true {}\n\nAfter:\n\n    if x {}\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1003\"",
							"Doc": "Replace call to strings.Index with strings.Contains\n\nBefore:\n\n    if strings.Index(x, y) != -1 {}\n\nAfter:\n\n    if strings.Contains(x, y) {}\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1004\"",
							"Doc": "Replace call to bytes.Compare with bytes.Equal\n\nBefore:\n\n    if bytes.Compare(x, y) == 0 {}\n\nAfter:\n\n    if bytes.Equal(x, y) {}\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1005\"",
							"Doc": "Drop unnecessary use of the blank identifier\n\nIn many cases, assigning to the blank identifier is unnecessary.\n\nBefore:\n\n    for _ = range s {}\n    x, _ = someMap[key]\n    _ = \u003c-ch\n\nAfter:\n\n    for range s{}\n    x = someMap[key]\n    \u003c-ch\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1006\"",
							"Doc": "Use 'for { ... }' for infinite loops\n\nFor infinite loops, using for { ... } is the most idiomatic choice.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1007\"",
							"Doc": "Simplify regular expression by using raw string literal\n\nRaw string literals use backticks instead of quotation marks and do not support\nany escape sequences. This means that the backslash can be used\nfreely, without the need of escaping.\n\nSince regular expressions have their own escape sequences, raw strings\ncan improve their readability.\n\nBefore:\n\n    regexp.Compile(\"\\\\A(\\\\w+) profile: total \\\\d+\\\\n\\\\z\")\n\nAfter:\n\n    regexp.Compile(`\\A(\\w+) profile: total \\d+\\n\\z`)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1008\"",
							"Doc": "Simplify returning boolean expression\n\nBefore:\n\n    if \u003cexpr\u003e {\n        return true\n    }\n    return false\n\nAfter:\n\n    return \u003cexpr\u003e\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1009\"",
							"Doc": "Omit redundant nil check on slices, maps, and channels\n\nThe len function is defined for all slices, maps, and\nchannels, even nil ones, which have a length of zero. It is not necessary to\ncheck for nil before checking that their length is not zero.\n\nBefore:\n\n    if x != nil \u0026\u0026 len(x) != 0 {}\n\nAfter:\n\n    if len(x) != 0 {}\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1010\"",
							"Doc": "Omit default slice index\n\nWhen slicing, the second index defaults to the length of the value,\nmaking s[n:len(s)] and s[n:] equivalent.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1011\"",
							"Doc": "Use a single append to concatenate two slices\n\nBefore:\n\n    for _, e := range y {\n        x = append(x, e)\n    }\n    \n    for i := range y {\n        x = append(x, y[i])\n    }\n    \n    for i := range y {\n        v := y[i]\n        x = append(x, v)\n    }\n\nAfter:\n\n    x = append(x, y...)\n    x = append(x, y...)\n    x = append(x, y...)\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1012\"",
							"Doc": "Replace time.Now().Sub(x) with time.Since(x)\n\nThe time.Since helper has the same effect as using time.Now().Sub(x)\nbut is easier to read.\n\nBefore:\n\n    time.Now().Sub(x)\n\nAfter:\n\n    time.Since(x)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1016\"",
							"Doc": "Use a type conversion instead of manually copying struct fields\n\nTwo struct types with identical fields can be converted between each\nother. In older versions of Go, the fields had to have identical\nstruct tags. Since Go 1.8, however, struct tags are ignored during\nconversions. It is thus not necessary to manually copy every field\nindividually.\n\nBefore:\n\n    var x T1\n    y := T2{\n        Field1: x.Field1,\n        Field2: x.Field2,\n    }\n\nAfter:\n\n    var x T1\n    y := T2(x)\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1017\"",
							"Doc": "Replace manual trimming with strings.TrimPrefix\n\nInstead of using strings.HasPrefix and manual slicing, use the\nstrings.TrimPrefix function. If the string doesn't start with the\nprefix, the original string will be returned. Using strings.TrimPrefix\nreduces complexity, and avoids common bugs, such as off-by-one\nmistakes.\n\nBefore:\n\n    if strings.HasPrefix(str, prefix) {\n        str = str[len(prefix):]\n    }\n\nAfter:\n\n    str = strings.TrimPrefix(str, prefix)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1018\"",
							"Doc": "Use 'copy' for sliding elements\n\ncopy() permits using the same source and destination slice, even with\noverlapping ranges. This makes it ideal for sliding elements in a\nslice.\n\nBefore:\n\n    for i := 0; i \u003c n; i++ {\n        bs[i] = bs[offset+i]\n    }\n\nAfter:\n\n    copy(bs[:n], bs[offset:])\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1019\"",
							"Doc": "Simplify 'make' call by omitting redundant arguments\n\nThe 'make' function has default values for the length and capacity\narguments. For channels, the length defaults to zero, and for slices,\nthe capacity defaults to the length.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1020\"",
							"Doc": "Omit redundant nil check in type assertion\n\nBefore:\n\n    if _, ok := i.(T); ok \u0026\u0026 i != nil {}\n\nAfter:\n\n    if _, ok := i.(T); ok {}\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1021\"",
							"Doc": "Merge variable declaration and assignment\n\nBefore:\n\n    var x uint\n    x = 1\n\nAfter:\n\n    var x uint = 1\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1023\"",
							"Doc": "Omit redundant control flow\n\nFunctions that have no return value do not need a return statement as\nthe final statement of the function.\n\nSwitches in Go do not have automatic fallthrough, unlike languages\nlike C. It is not necessary to have a break statement as the final\nstatement in a case block.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1024\"",
							"Doc": "Replace x.Sub(time.Now()) with time.Until(x)\n\nThe time.Until helper has the same effect as using x.Sub(time.Now())\nbut is easier to read.\n\nBefore:\n\n    x.Sub(time.Now())\n\nAfter:\n\n    time.Until(x)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1025\"",
							"Doc": "Don't use fmt.Sprintf(\"%s\", x) unnecessarily\n\nIn many instances, there are easier and more efficient ways of getting\na value's string representation. Whenever a value's underlying type is\na string already, or the type has a String method, they should be used\ndirectly.\n\nGiven the following shared definitions\n\n    type T1 string\n    type T2 int\n\n    func (T2) String() string { return \"Hello, world\" }\n\n    var x string\n    var y T1\n    var z T2\n\nwe can simplify\n\n    fmt.Sprintf(\"%s\", x)\n    fmt.Sprintf(\"%s\", y)\n    fmt.Sprintf(\"%s\", z)\n\nto\n\n    x\n    string(y)\n    z.String()\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1028\"",
							"Doc": "Simplify error construction with fmt.Errorf\n\nBefore:\n\n    errors.New(fmt.Sprintf(...))\n\nAfter:\n\n    fmt.Errorf(...)\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1029\"",
							"Doc": "Range over the string directly\n\nRanging over a string will yield byte offsets and runes. If the offset\nisn't used, this is functionally equivalent to converting the string\nto a slice of runes and ranging over that. Ranging directly over the\nstring will be more performant, however, as it avoids allocating a new\nslice, the size of which depends on the length of the string.\n\nBefore:\n\n    for _, r := range []rune(s) {}\n\nAfter:\n\n    for _, r := range s {}\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"S1030\"",
							"Doc": "Use bytes.Buffer.String or bytes.Buffer.Bytes\n\nbytes.Buffer has both a String and a Bytes method. It is almost never\nnecessary to use string(buf.Bytes()) or []byte(buf.String()) – simply\nuse the other method.\n\nThe only exception to this are map lookups. Due to a compiler optimization,\nm[string(buf.Bytes())] is more efficient than m[buf.String()].\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1031\"",
							"Doc": "Omit redundant nil check around loop\n\nYou can use range on nil slices and maps, the loop will simply never\nexecute. This makes an additional nil check around the loop\nunnecessary.\n\nBefore:\n\n    if s != nil {\n        for _, x := range s {\n            ...\n        }\n    }\n\nAfter:\n\n    for _, x := range s {\n        ...\n    }\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1032\"",
							"Doc": "Use sort.Ints(x), sort.Float64s(x), and sort.Strings(x)\n\nThe sort.Ints, sort.Float64s and sort.Strings functions are easier to\nread than sort.Sort(sort.IntSlice(x)), sort.Sort(sort.Float64Slice(x))\nand sort.Sort(sort.StringSlice(x)).\n\nBefore:\n\n    sort.Sort(sort.StringSlice(x))\n\nAfter:\n\n    sort.Strings(x)\n\nAvailable since\n    2019.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1033\"",
							"Doc": "Unnecessary guard around call to 'delete'\n\nCalling delete on a nil map is a no-op.\n\nAvailable since\n    2019.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1034\"",
							"Doc": "Use result of type assertion to simplify cases\n\nAvailable since\n    2019.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1035\"",
							"Doc": "Redundant call to net/http.CanonicalHeaderKey in method call on net/http.Header\n\nThe methods on net/http.Header, namely Add, Del, Get\nand Set, already canonicalize the given header name.\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1036\"",
							"Doc": "Unnecessary guard around map access\n\nWhen accessing a map key that doesn't exist yet, one receives a zero\nvalue. Often, the zero value is a suitable value, for example when\nusing append or doing integer math.\n\nThe following\n\n    if _, ok := m[\"foo\"]; ok {\n        m[\"foo\"] = append(m[\"foo\"], \"bar\")\n    } else {\n        m[\"foo\"] = []string{\"bar\"}\n    }\n\ncan be simplified to\n\n    m[\"foo\"] = append(m[\"foo\"], \"bar\")\n\nand\n\n    if _, ok := m2[\"k\"]; ok {\n        m2[\"k\"] += 4\n    } else {\n        m2[\"k\"] = 4\n    }\n\ncan be simplified to\n\n    m[\"k\"] += 4\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1037\"",
							"Doc": "Elaborate way of sleeping\n\nUsing a select statement with a single case receiving\nfrom the result of time.After is a very elaborate way of sleeping that\ncan much simpler be expressed with a simple call to time.Sleep.\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1038\"",
							"Doc": "Unnecessarily complex way of printing formatted string\n\nInstead of using fmt.Print(fmt.Sprintf(...)), one can use fmt.Printf(...).\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1039\"",
							"Doc": "Unnecessary use of fmt.Sprint\n\nCalling fmt.Sprint with a single string argument is unnecessary\nand identical to using the string directly.\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"S1040\"",
							"Doc": "Type assertion to current type\n\nThe type assertion x.(SomeInterface), when x already has type\nSomeInterface, can only fail if x is nil. Usually, this is\nleft-over code from when x had a different type and you can safely\ndelete the type assertion. If you want to check that x is not nil,\nconsider being explicit and using an actual if x == nil comparison\ninstead of relying on the type assertion panicking.\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1000\"",
							"Doc": "Invalid regular expression\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1001\"",
							"Doc": "Invalid template\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1002\"",
							"Doc": "Invalid format in time.Parse\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1003\"",
							"Doc": "Unsupported argument to functions in encoding/binary\n\nThe encoding/binary package can only serialize types with known sizes.\nThis precludes the use of the int and uint types, as their sizes\ndiffer on different architectures. Furthermore, it doesn't support\nserializing maps, channels, strings, or functions.\n\nBefore Go 1.8, bool wasn't supported, either.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1004\"",
							"Doc": "Suspiciously small untyped constant in time.Sleep\n\nThe time.Sleep function takes a time.Duration as its only argument.\nDurations are expressed in nanoseconds. Thus, calling time.Sleep(1)\nwill sleep for 1 nanosecond. This is a common source of bugs, as sleep\nfunctions in other languages often accept seconds or milliseconds.\n\nThe time package provides constants such as time.Second to express\nlarge durations. These can be combined with arithmetic to express\narbitrary durations, for example 5 * time.Second for 5 seconds.\n\nIf you truly meant to sleep for a tiny amount of time, use\nn * time.Nanosecond to signal to Staticcheck that you did mean to sleep\nfor some amount of nanoseconds.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1005\"",
							"Doc": "Invalid first argument to exec.Command\n\nos/exec runs programs directly (using variants of the fork and exec\nsystem calls on Unix systems). This shouldn't be confused with running\na command in a shell. The shell will allow for features such as input\nredirection, pipes, and general scripting. The shell is also\nresponsible for splitting the user's input into a program name and its\narguments. For example, the equivalent to\n\n    ls / /tmp\n\nwould be\n\n    exec.Command(\"ls\", \"/\", \"/tmp\")\n\nIf you want to run a command in a shell, consider using something like\nthe following – but be aware that not all systems, particularly\nWindows, will have a /bin/sh program:\n\n    exec.Command(\"/bin/sh\", \"-c\", \"ls | grep Awesome\")\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1007\"",
							"Doc": "Invalid URL in net/url.Parse\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1008\"",
							"Doc": "Non-canonical key in http.Header map\n\nKeys in http.Header maps are canonical, meaning they follow a specific\ncombination of uppercase and lowercase letters. Methods such as\nhttp.Header.Add and http.Header.Del convert inputs into this canonical\nform before manipulating the map.\n\nWhen manipulating http.Header maps directly, as opposed to using the\nprovided methods, care should be taken to stick to canonical form in\norder to avoid inconsistencies. The following piece of code\ndemonstrates one such inconsistency:\n\n    h := http.Header{}\n    h[\"etag\"] = []string{\"1234\"}\n    h.Add(\"etag\", \"5678\")\n    fmt.Println(h)\n\n    // Output:\n    // map[Etag:[5678] etag:[1234]]\n\nThe easiest way of obtaining the canonical form of a key is to use\nhttp.CanonicalHeaderKey.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1010\"",
							"Doc": "(*regexp.Regexp).FindAll called with n == 0, which will always return zero results\n\nIf n \u003e= 0, the function returns at most n matches/submatches. To\nreturn all results, specify a negative number.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1011\"",
							"Doc": "Various methods in the 'strings' package expect valid UTF-8, but invalid input is provided\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1012\"",
							"Doc": "A nil context.Context is being passed to a function, consider using context.TODO instead\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1013\"",
							"Doc": "io.Seeker.Seek is being called with the whence constant as the first argument, but it should be the second\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1014\"",
							"Doc": "Non-pointer value passed to Unmarshal or Decode\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1015\"",
							"Doc": "Using time.Tick in a way that will leak. Consider using time.NewTicker, and only use time.Tick in tests, commands and endless functions\n\nBefore Go 1.23, time.Tickers had to be closed to be able to be garbage\ncollected. Since time.Tick doesn't make it possible to close the underlying\nticker, using it repeatedly would leak memory.\n\nGo 1.23 fixes this by allowing tickers to be collected even if they weren't closed.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1016\"",
							"Doc": "Trapping a signal that cannot be trapped\n\nNot all signals can be intercepted by a process. Specifically, on\nUNIX-like systems, the syscall.SIGKILL and syscall.SIGSTOP signals are\nnever passed to the process, but instead handled directly by the\nkernel. It is therefore pointless to try and handle these signals.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA1017\"",
							"Doc": "Channels used with os/signal.Notify should be buffered\n\nThe os/signal package uses non-blocking channel sends when delivering\nsignals. If the receiving end of the channel isn't ready and the\nchannel is either unbuffered or full, the signal will be dropped. To\navoid missing signals, the channel should be buffered and of the\nappropriate size. For a channel used for notification of just one\nsignal value, a buffer of size 1 is sufficient.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1018\"",
							"Doc": "strings.Replace called with n == 0, which does nothing\n\nWith n == 0, zero instances will be replaced. To replace all\ninstances, use a negative number, or use strings.ReplaceAll.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1020\"",
							"Doc": "Using an invalid host:port pair with a net.Listen-related function\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1021\"",
							"Doc": "Using bytes.Equal to compare two net.IP\n\nA net.IP stores an IPv4 or IPv6 address as a slice of bytes. The\nlength of the slice for an IPv4 address, however, can be either 4 or\n16 bytes long, using different ways of representing IPv4 addresses. In\norder to correctly compare two net.IPs, the net.IP.Equal method should\nbe used, as it takes both representations into account.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1023\"",
							"Doc": "Modifying the buffer in an io.Writer implementation\n\nWrite must not modify the slice data, even temporarily.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1024\"",
							"Doc": "A string cutset contains duplicate characters\n\nThe strings.TrimLeft and strings.TrimRight functions take cutsets, not\nprefixes. A cutset is treated as a set of characters to remove from a\nstring. For example,\n\n    strings.TrimLeft(\"42133word\", \"1234\")\n\nwill result in the string \"word\" – any characters that are 1, 2, 3 or\n4 are cut from the left of the string.\n\nIn order to remove one string from another, use strings.TrimPrefix instead.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1025\"",
							"Doc": "It is not possible to use (*time.Timer).Reset's return value correctly\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1026\"",
							"Doc": "Cannot marshal channels or functions\n\nAvailable since\n    2019.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1027\"",
							"Doc": "Atomic access to 64-bit variable must be 64-bit aligned\n\nOn ARM, x86-32, and 32-bit MIPS, it is the caller's responsibility to\narrange for 64-bit alignment of 64-bit words accessed atomically. The\nfirst word in a variable or in an allocated struct, array, or slice\ncan be relied upon to be 64-bit aligned.\n\nYou can use the structlayout tool to inspect the alignment of fields\nin a struct.\n\nAvailable since\n    2019.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1028\"",
							"Doc": "sort.Slice can only be used on slices\n\nThe first argument of sort.Slice must be a slice.\n\nAvailable since\n    2020.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1029\"",
							"Doc": "Inappropriate key in call to context.WithValue\n\nThe provided key must be comparable and should not be\nof type string or any other built-in type to avoid collisions between\npackages using context. Users of WithValue should define their own\ntypes for keys.\n\nTo avoid allocating when assigning to an interface{},\ncontext keys often have concrete type struct{}. Alternatively,\nexported context key variables' static type should be a pointer or\ninterface.\n\nAvailable since\n    2020.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1030\"",
							"Doc": "Invalid argument in call to a strconv function\n\nThis check validates the format, number base and bit size arguments of\nthe various parsing and formatting functions in strconv.\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1031\"",
							"Doc": "Overlapping byte slices passed to an encoder\n\nIn an encoding function of the form Encode(dst, src), dst and\nsrc were found to reference the same memory. This can result in\nsrc bytes being overwritten before they are read, when the encoder\nwrites more than one byte per src byte.\n\nAvailable since\n    2024.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA1032\"",
							"Doc": "Wrong order of arguments to errors.Is\n\nThe first argument of the function errors.Is is the error\nthat we have and the second argument is the error we're trying to match against.\nFor example:\n\n\tif errors.Is(err, io.EOF) { ... }\n\nThis check detects some cases where the two arguments have been swapped. It\nflags any calls where the first argument is referring to a package-level error\nvariable, such as\n\n\tif errors.Is(io.EOF, err) { /* this is wrong */ }\n\nAvailable since\n    2024.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA2001\"",
							"Doc": "Empty critical section, did you mean to defer the unlock?\n\nEmpty critical sections of the kind\n\n    mu.Lock()\n    mu.Unlock()\n\nare very often a typo, and the following was intended instead:\n\n    mu.Lock()\n    defer mu.Unlock()\n\nDo note that sometimes empty critical sections can be useful, as a\nform of signaling to wait on another goroutine. Many times, there are\nsimpler ways of achieving the same effect. When that isn't the case,\nthe code should be amply commented to avoid confusion. Combining such\ncomments with a //lint:ignore directive can be used to suppress this\nrare false positive.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA2002\"",
							"Doc": "Called testing.T.FailNow or SkipNow in a goroutine, which isn't allowed\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA2003\"",
							"Doc": "Deferred Lock right after locking, likely meant to defer Unlock instead\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA3000\"",
							"Doc": "TestMain doesn't call os.Exit, hiding test failures\n\nTest executables (and in turn 'go test') exit with a non-zero status\ncode if any tests failed. When specifying your own TestMain function,\nit is your responsibility to arrange for this, by calling os.Exit with\nthe correct code. The correct code is returned by (*testing.M).Run, so\nthe usual way of implementing TestMain is to end it with\nos.Exit(m.Run()).\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA3001\"",
							"Doc": "Assigning to b.N in benchmarks distorts the results\n\nThe testing package dynamically sets b.N to improve the reliability of\nbenchmarks and uses it in computations to determine the duration of a\nsingle operation. Benchmark code must not alter b.N as this would\nfalsify results.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4000\"",
							"Doc": "Binary operator has identical expressions on both sides\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4001\"",
							"Doc": "\u0026*x gets simplified to x, it does not copy x\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4003\"",
							"Doc": "Comparing unsigned values against negative values is pointless\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4004\"",
							"Doc": "The loop exits unconditionally after one iteration\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4005\"",
							"Doc": "Field assignment that will never be observed. Did you mean to use a pointer receiver?\n\nAvailable since\n    2021.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4006\"",
							"Doc": "A value assigned to a variable is never read before being overwritten. Forgotten error check or dead code?\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4008\"",
							"Doc": "The variable in the loop condition never changes, are you incrementing the wrong variable?\n\nFor example:\n\n\tfor i := 0; i \u003c 10; j++ { ... }\n\nThis may also occur when a loop can only execute once because of unconditional\ncontrol flow that terminates the loop. For example, when a loop body contains an\nunconditional break, return, or panic:\n\n\tfunc f() {\n\t\tpanic(\"oops\")\n\t}\n\tfunc g() {\n\t\tfor i := 0; i \u003c 10; i++ {\n\t\t\t// f unconditionally calls panic, which means \"i\" is\n\t\t\t// never incremented.\n\t\t\tf()\n\t\t}\n\t}\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4009\"",
							"Doc": "A function argument is overwritten before its first use\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4010\"",
							"Doc": "The result of append will never be observed anywhere\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4011\"",
							"Doc": "Break statement with no effect. Did you mean to break out of an outer loop?\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4012\"",
							"Doc": "Comparing a value against NaN even though no value is equal to NaN\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4013\"",
							"Doc": "Negating a boolean twice (!!b) is the same as writing b. This is either redundant, or a typo.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4014\"",
							"Doc": "An if/else if chain has repeated conditions and no side-effects; if the condition didn't match the first time, it won't match the second time, either\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4015\"",
							"Doc": "Calling functions like math.Ceil on floats converted from integers doesn't do anything useful\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4016\"",
							"Doc": "Certain bitwise operations, such as x ^ 0, do not do anything useful\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4017\"",
							"Doc": "Discarding the return values of a function without side effects, making the call pointless\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4018\"",
							"Doc": "Self-assignment of variables\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4019\"",
							"Doc": "Multiple, identical build constraints in the same file\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4020\"",
							"Doc": "Unreachable case clause in a type switch\n\nIn a type switch like the following\n\n    type T struct{}\n    func (T) Read(b []byte) (int, error) { return 0, nil }\n\n    var v any = T{}\n\n    switch v.(type) {\n    case io.Reader:\n        // ...\n    case T:\n        // unreachable\n    }\n\nthe second case clause can never be reached because T implements\nio.Reader and case clauses are evaluated in source order.\n\nAnother example:\n\n    type T struct{}\n    func (T) Read(b []byte) (int, error) { return 0, nil }\n    func (T) Close() error { return nil }\n\n    var v any = T{}\n\n    switch v.(type) {\n    case io.Reader:\n        // ...\n    case io.ReadCloser:\n        // unreachable\n    }\n\nEven though T has a Close method and thus implements io.ReadCloser,\nio.Reader will always match first. The method set of io.Reader is a\nsubset of io.ReadCloser. Thus it is impossible to match the second\ncase without matching the first case.\n\n\nStructurally equivalent interfaces\n\nA special case of the previous example are structurally identical\ninterfaces. Given these declarations\n\n    type T error\n    type V error\n\n    func doSomething() error {\n        err, ok := doAnotherThing()\n        if ok {\n            return T(err)\n        }\n\n        return U(err)\n    }\n\nthe following type switch will have an unreachable case clause:\n\n    switch doSomething().(type) {\n    case T:\n        // ...\n    case V:\n        // unreachable\n    }\n\nT will always match before V because they are structurally equivalent\nand therefore doSomething()'s return value implements both.\n\nAvailable since\n    2019.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4022\"",
							"Doc": "Comparing the address of a variable against nil\n\nCode such as 'if \u0026x == nil' is meaningless, because taking the address of a variable always yields a non-nil pointer.\n\nAvailable since\n    2020.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4023\"",
							"Doc": "Impossible comparison of interface value with untyped nil\n\nUnder the covers, interfaces are implemented as two elements, a\ntype T and a value V. V is a concrete value such as an int,\nstruct or pointer, never an interface itself, and has type T. For\ninstance, if we store the int value 3 in an interface, the\nresulting interface value has, schematically, (T=int, V=3). The\nvalue V is also known as the interface's dynamic value, since a\ngiven interface variable might hold different values V (and\ncorresponding types T) during the execution of the program.\n\nAn interface value is nil only if the V and T are both\nunset, (T=nil, V is not set), In particular, a nil interface will\nalways hold a nil type. If we store a nil pointer of type *int\ninside an interface value, the inner type will be *int regardless\nof the value of the pointer: (T=*int, V=nil). Such an interface\nvalue will therefore be non-nil even when the pointer value V\ninside is nil.\n\nThis situation can be confusing, and arises when a nil value is\nstored inside an interface value such as an error return:\n\n    func returnsError() error {\n        var p *MyError = nil\n        if bad() {\n            p = ErrBad\n        }\n        return p // Will always return a non-nil error.\n    }\n\nIf all goes well, the function returns a nil p, so the return\nvalue is an error interface value holding (T=*MyError, V=nil).\nThis means that if the caller compares the returned error to nil,\nit will always look as if there was an error even if nothing bad\nhappened. To return a proper nil error to the caller, the\nfunction must return an explicit nil:\n\n    func returnsError() error {\n        if bad() {\n            return ErrBad\n        }\n        return nil\n    }\n\nIt's a good idea for functions that return errors always to use\nthe error type in their signature (as we did above) rather than a\nconcrete type such as *MyError, to help guarantee the error is\ncreated correctly. As an example, os.Open returns an error even\nthough, if not nil, it's always of concrete type *os.PathError.\n\nSimilar situations to those described here can arise whenever\ninterfaces are used. Just keep in mind that if any concrete value\nhas been stored in the interface, the interface will not be nil.\nFor more information, see The Laws of\nReflection at https://golang.org/doc/articles/laws_of_reflection.html.\n\nThis text has been copied from\nhttps://golang.org/doc/faq#nil_error, licensed under the Creative\nCommons Attribution 3.0 License.\n\nAvailable since\n    2020.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4024\"",
							"Doc": "Checking for impossible return value from a builtin function\n\nReturn values of the len and cap builtins cannot be negative.\n\nSee https://golang.org/pkg/builtin/#len and https://golang.org/pkg/builtin/#cap.\n\nExample:\n\n    if len(slice) \u003c 0 {\n        fmt.Println(\"unreachable code\")\n    }\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4025\"",
							"Doc": "Integer division of literals that results in zero\n\nWhen dividing two integer constants, the result will\nalso be an integer. Thus, a division such as 2 / 3 results in 0.\nThis is true for all of the following examples:\n\n\t_ = 2 / 3\n\tconst _ = 2 / 3\n\tconst _ float64 = 2 / 3\n\t_ = float64(2 / 3)\n\nStaticcheck will flag such divisions if both sides of the division are\ninteger literals, as it is highly unlikely that the division was\nintended to truncate to zero. Staticcheck will not flag integer\ndivision involving named constants, to avoid noisy positives.\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4026\"",
							"Doc": "Go constants cannot express negative zero\n\nIn IEEE 754 floating point math, zero has a sign and can be positive\nor negative. This can be useful in certain numerical code.\n\nGo constants, however, cannot express negative zero. This means that\nthe literals -0.0 and 0.0 have the same ideal value (zero) and\nwill both represent positive zero at runtime.\n\nTo explicitly and reliably create a negative zero, you can use the\nmath.Copysign function: math.Copysign(0, -1).\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4027\"",
							"Doc": "(*net/url.URL).Query returns a copy, modifying it doesn't change the URL\n\n(*net/url.URL).Query parses the current value of net/url.URL.RawQuery\nand returns it as a map of type net/url.Values. Subsequent changes to\nthis map will not affect the URL unless the map gets encoded and\nassigned to the URL's RawQuery.\n\nAs a consequence, the following code pattern is an expensive no-op:\nu.Query().Add(key, value).\n\nAvailable since\n    2021.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4028\"",
							"Doc": "x % 1 is always zero\n\nAvailable since\n    2022.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4029\"",
							"Doc": "Ineffective attempt at sorting slice\n\nsort.Float64Slice, sort.IntSlice, and sort.StringSlice are\ntypes, not functions. Doing x = sort.StringSlice(x) does nothing,\nespecially not sort any values. The correct usage is\nsort.Sort(sort.StringSlice(x)) or sort.StringSlice(x).Sort(),\nbut there are more convenient helpers, namely sort.Float64s,\nsort.Ints, and sort.Strings.\n\nAvailable since\n    2022.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4030\"",
							"Doc": "Ineffective attempt at generating random number\n\nFunctions in the math/rand package that accept upper limits, such\nas Intn, generate random numbers in the half-open interval [0,n). In\nother words, the generated numbers will be \u003e= 0 and \u003c n – they\ndon't include n. rand.Intn(1) therefore doesn't generate 0\nor 1, it always generates 0.\n\nAvailable since\n    2022.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA4031\"",
							"Doc": "Checking never-nil value against nil\n\nAvailable since\n    2022.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA4032\"",
							"Doc": "Comparing runtime.GOOS or runtime.GOARCH against impossible value\n\nAvailable since\n    2024.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA5000\"",
							"Doc": "Assignment to nil map\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5001\"",
							"Doc": "Deferring Close before checking for a possible error\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA5002\"",
							"Doc": "The empty for loop ('for {}') spins and can block the scheduler\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5003\"",
							"Doc": "Defers in infinite loops will never execute\n\nDefers are scoped to the surrounding function, not the surrounding\nblock. In a function that never returns, i.e. one containing an\ninfinite loop, defers will never execute.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA5004\"",
							"Doc": "'for { select { ...' with an empty default branch spins\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA5005\"",
							"Doc": "The finalizer references the finalized object, preventing garbage collection\n\nA finalizer is a function associated with an object that runs when the\ngarbage collector is ready to collect said object, that is when the\nobject is no longer referenced by anything.\n\nIf the finalizer references the object, however, it will always remain\nas the final reference to that object, preventing the garbage\ncollector from collecting the object. The finalizer will never run,\nand the object will never be collected, leading to a memory leak. That\nis why the finalizer should instead use its first argument to operate\non the object. That way, the number of references can temporarily go\nto zero before the object is being passed to the finalizer.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5007\"",
							"Doc": "Infinite recursive call\n\nA function that calls itself recursively needs to have an exit\ncondition. Otherwise it will recurse forever, until the system runs\nout of memory.\n\nThis issue can be caused by simple bugs such as forgetting to add an\nexit condition. It can also happen \"on purpose\". Some languages have\ntail call optimization which makes certain infinite recursive calls\nsafe to use. Go, however, does not implement TCO, and as such a loop\nshould be used instead.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5008\"",
							"Doc": "Invalid struct tag\n\nAvailable since\n    2019.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA5010\"",
							"Doc": "Impossible type assertion\n\nSome type assertions can be statically proven to be\nimpossible. This is the case when the method sets of both\narguments of the type assertion conflict with each other, for\nexample by containing the same method with different\nsignatures.\n\nThe Go compiler already applies this check when asserting from an\ninterface value to a concrete type. If the concrete type misses\nmethods from the interface, or if function signatures don't match,\nthen the type assertion can never succeed.\n\nThis check applies the same logic when asserting from one interface to\nanother. If both interface types contain the same method but with\ndifferent signatures, then the type assertion can never succeed,\neither.\n\nAvailable since\n    2020.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5011\"",
							"Doc": "Possible nil pointer dereference\n\nA pointer is being dereferenced unconditionally, while\nalso being checked against nil in another place. This suggests that\nthe pointer may be nil and dereferencing it may panic. This is\ncommonly a result of improperly ordered code or missing return\nstatements. Consider the following examples:\n\n    func fn(x *int) {\n        fmt.Println(*x)\n\n        // This nil check is equally important for the previous dereference\n        if x != nil {\n            foo(*x)\n        }\n    }\n\n    func TestFoo(t *testing.T) {\n        x := compute()\n        if x == nil {\n            t.Errorf(\"nil pointer received\")\n        }\n\n        // t.Errorf does not abort the test, so if x is nil, the next line will panic.\n        foo(*x)\n    }\n\nStaticcheck tries to deduce which functions abort control flow.\nFor example, it is aware that a function will not continue\nexecution after a call to panic or log.Fatal. However, sometimes\nthis detection fails, in particular in the presence of\nconditionals. Consider the following example:\n\n    func Log(msg string, level int) {\n        fmt.Println(msg)\n        if level == levelFatal {\n            os.Exit(1)\n        }\n    }\n\n    func Fatal(msg string) {\n        Log(msg, levelFatal)\n    }\n\n    func fn(x *int) {\n        if x == nil {\n            Fatal(\"unexpected nil pointer\")\n        }\n        fmt.Println(*x)\n    }\n\nStaticcheck will flag the dereference of x, even though it is perfectly\nsafe. Staticcheck is not able to deduce that a call to\nFatal will exit the program. For the time being, the easiest\nworkaround is to modify the definition of Fatal like so:\n\n    func Fatal(msg string) {\n        Log(msg, levelFatal)\n        panic(\"unreachable\")\n    }\n\nWe also hard-code functions from common logging packages such as\nlogrus. Please file an issue if we're missing support for a\npopular package.\n\nAvailable since\n    2020.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA5012\"",
							"Doc": "Passing odd-sized slice to function expecting even size\n\nSome functions that take slices as parameters expect the slices to have an even number of elements. \nOften, these functions treat elements in a slice as pairs. \nFor example, strings.NewReplacer takes pairs of old and new strings, \nand calling it with an odd number of elements would be an error.\n\nAvailable since\n    2020.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA6000\"",
							"Doc": "Using regexp.Match or related in a loop, should use regexp.Compile\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA6001\"",
							"Doc": "Missing an optimization opportunity when indexing maps by byte slices\n\nMap keys must be comparable, which precludes the use of byte slices.\nThis usually leads to using string keys and converting byte slices to\nstrings.\n\nNormally, a conversion of a byte slice to a string needs to copy the data and\ncauses allocations. The compiler, however, recognizes m[string(b)] and\nuses the data of b directly, without copying it, because it knows that\nthe data can't change during the map lookup. This leads to the\ncounter-intuitive situation that\n\n    k := string(b)\n    println(m[k])\n    println(m[k])\n\nwill be less efficient than\n\n    println(m[string(b)])\n    println(m[string(b)])\n\nbecause the first version needs to copy and allocate, while the second\none does not.\n\nFor some history on this optimization, check out commit\nf5f5a8b6209f84961687d993b93ea0d397f5d5bf in the Go repository.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA6002\"",
							"Doc": "Storing non-pointer values in sync.Pool allocates memory\n\nA sync.Pool is used to avoid unnecessary allocations and reduce the\namount of work the garbage collector has to do.\n\nWhen passing a value that is not a pointer to a function that accepts\nan interface, the value needs to be placed on the heap, which means an\nadditional allocation. Slices are a common thing to put in sync.Pools,\nand they're structs with 3 fields (length, capacity, and a pointer to\nan array). In order to avoid the extra allocation, one should store a\npointer to the slice instead.\n\nSee the comments on https://go-review.googlesource.com/c/go/+/24371\nthat discuss this problem.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA6003\"",
							"Doc": "Converting a string to a slice of runes before ranging over it\n\nYou may want to loop over the runes in a string. Instead of converting\nthe string to a slice of runes and looping over that, you can loop\nover the string itself. That is,\n\n    for _, r := range s {}\n\nand\n\n    for _, r := range []rune(s) {}\n\nwill yield the same values. The first version, however, will be faster\nand avoid unnecessary memory allocations.\n\nDo note that if you are interested in the indices, ranging over a\nstring and over a slice of runes will yield different indices. The\nfirst one yields byte offsets, while the second one yields indices in\nthe slice of runes.\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA6005\"",
							"Doc": "Inefficient string comparison with strings.ToLower or strings.ToUpper\n\nConverting two strings to the same case and comparing them like so\n\n    if strings.ToLower(s1) == strings.ToLower(s2) {\n        ...\n    }\n\nis significantly more expensive than comparing them with\nstrings.EqualFold(s1, s2). This is due to memory usage as well as\ncomputational complexity.\n\nstrings.ToLower will have to allocate memory for the new strings, as\nwell as convert both strings fully, even if they differ on the very\nfirst byte. strings.EqualFold, on the other hand, compares the strings\none character at a time. It doesn't need to create two intermediate\nstrings and can return as soon as the first non-matching character has\nbeen found.\n\nFor a more in-depth explanation of this issue, see\nhttps://blog.digitalocean.com/how-to-efficiently-compare-strings-in-go/\n\nAvailable since\n    2019.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA6006\"",
							"Doc": "Using io.WriteString to write []byte\n\nUsing io.WriteString to write a slice of bytes, as in\n\n    io.WriteString(w, string(b))\n\nis both unnecessary and inefficient. Converting from []byte to string\nhas to allocate and copy the data, and we could simply use w.Write(b)\ninstead.\n\nAvailable since\n    2024.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA9001\"",
							"Doc": "Defers in range loops may not run when you expect them to\n\nAvailable since\n    2017.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA9002\"",
							"Doc": "Using a non-octal os.FileMode that looks like it was meant to be in octal.\n\nAvailable since\n    2017.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA9003\"",
							"Doc": "Empty body in an if or else branch\n\nAvailable since\n    2017.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA9004\"",
							"Doc": "Only the first constant has an explicit type\n\nIn a constant declaration such as the following:\n\n    const (\n        First byte = 1\n        Second     = 2\n    )\n\nthe constant Second does not have the same type as the constant First.\nThis construct shouldn't be confused with\n\n    const (\n        First byte = iota\n        Second\n    )\n\nwhere First and Second do indeed have the same type. The type is only\npassed on when no explicit value is assigned to the constant.\n\nWhen declaring enumerations with explicit values it is therefore\nimportant not to write\n\n    const (\n          EnumFirst EnumType = 1\n          EnumSecond         = 2\n          EnumThird          = 3\n    )\n\nThis discrepancy in types can cause various confusing behaviors and\nbugs.\n\n\nWrong type in variable declarations\n\nThe most obvious issue with such incorrect enumerations expresses\nitself as a compile error:\n\n    package pkg\n\n    const (\n        EnumFirst  uint8 = 1\n        EnumSecond       = 2\n    )\n\n    func fn(useFirst bool) {\n        x := EnumSecond\n        if useFirst {\n            x = EnumFirst\n        }\n    }\n\nfails to compile with\n\n    ./const.go:11:5: cannot use EnumFirst (type uint8) as type int in assignment\n\n\nLosing method sets\n\nA more subtle issue occurs with types that have methods and optional\ninterfaces. Consider the following:\n\n    package main\n\n    import \"fmt\"\n\n    type Enum int\n\n    func (e Enum) String() string {\n        return \"an enum\"\n    }\n\n    const (\n        EnumFirst  Enum = 1\n        EnumSecond      = 2\n    )\n\n    func main() {\n        fmt.Println(EnumFirst)\n        fmt.Println(EnumSecond)\n    }\n\nThis code will output\n\n    an enum\n    2\n\nas EnumSecond has no explicit type, and thus defaults to int.\n\nAvailable since\n    2019.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA9005\"",
							"Doc": "Trying to marshal a struct with no public fields nor custom marshaling\n\nThe encoding/json and encoding/xml packages only operate on exported\nfields in structs, not unexported ones. It is usually an error to try\nto (un)marshal structs that only consist of unexported fields.\n\nThis check will not flag calls involving types that define custom\nmarshaling behavior, e.g. via MarshalJSON methods. It will also not\nflag empty structs.\n\nAvailable since\n    2019.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA9006\"",
							"Doc": "Dubious bit shifting of a fixed size integer value\n\nBit shifting a value past its size will always clear the value.\n\nFor instance:\n\n    v := int8(42)\n    v \u003e\u003e= 8\n\nwill always result in 0.\n\nThis check flags bit shifting operations on fixed size integer values only.\nThat is, int, uint and uintptr are never flagged to avoid potential false\npositives in somewhat exotic but valid bit twiddling tricks:\n\n    // Clear any value above 32 bits if integers are more than 32 bits.\n    func f(i int) int {\n        v := i \u003e\u003e 32\n        v = v \u003c\u003c 32\n        return i-v\n    }\n\nAvailable since\n    2020.2\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"SA9007\"",
							"Doc": "Deleting a directory that shouldn't be deleted\n\nIt is virtually never correct to delete system directories such as\n/tmp or the user's home directory. However, it can be fairly easy to\ndo by mistake, for example by mistakenly using os.TempDir instead\nof ioutil.TempDir, or by forgetting to add a suffix to the result\nof os.UserHomeDir.\n\nWriting\n\n    d := os.TempDir()\n    defer os.RemoveAll(d)\n\nin your unit tests will have a devastating effect on the stability of your system.\n\nThis check flags attempts at deleting the following directories:\n\n- os.TempDir\n- os.UserCacheDir\n- os.UserConfigDir\n- os.UserHomeDir\n\nAvailable since\n    2022.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA9008\"",
							"Doc": "else branch of a type assertion is probably not reading the right value\n\nWhen declaring variables as part of an if statement (like in 'if\nfoo := ...; foo {'), the same variables will also be in the scope of\nthe else branch. This means that in the following example\n\n    if x, ok := x.(int); ok {\n        // ...\n    } else {\n        fmt.Printf(\"unexpected type %T\", x)\n    }\n\nx in the else branch will refer to the x from x, ok\n:=; it will not refer to the x that is being type-asserted. The\nresult of a failed type assertion is the zero value of the type that\nis being asserted to, so x in the else branch will always have the\nvalue 0 and the type int.\n\nAvailable since\n    2022.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"SA9009\"",
							"Doc": "Ineffectual Go compiler directive\n\nA potential Go compiler directive was found, but is ineffectual as it begins\nwith whitespace.\n\nAvailable since\n    2024.1\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"ST1000\"",
							"Doc": "Incorrect or missing package comment\n\nPackages must have a package comment that is formatted according to\nthe guidelines laid out in\nhttps://go.dev/wiki/CodeReviewComments#package-comments.\n\nAvailable since\n    2019.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1001\"",
							"Doc": "Dot imports are discouraged\n\nDot imports that aren't in external test packages are discouraged.\n\nThe dot_import_whitelist option can be used to whitelist certain\nimports.\n\nQuoting Go Code Review Comments:\n\n\u003e The import . form can be useful in tests that, due to circular\n\u003e dependencies, cannot be made part of the package being tested:\n\u003e \n\u003e     package foo_test\n\u003e \n\u003e     import (\n\u003e         \"bar/testutil\" // also imports \"foo\"\n\u003e         . \"foo\"\n\u003e     )\n\u003e \n\u003e In this case, the test file cannot be in package foo because it\n\u003e uses bar/testutil, which imports foo. So we use the import .\n\u003e form to let the file pretend to be part of package foo even though\n\u003e it is not. Except for this one case, do not use import . in your\n\u003e programs. It makes the programs much harder to read because it is\n\u003e unclear whether a name like Quux is a top-level identifier in the\n\u003e current package or in an imported package.\n\nAvailable since\n    2019.1\n\nOptions\n    dot_import_whitelist\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1003\"",
							"Doc": "Poorly chosen identifier\n\nIdentifiers, such as variable and package names, follow certain rules.\n\nSee the following links for details:\n\n- https://go.dev/doc/effective_go#package-names\n- https://go.dev/doc/effective_go#mixed-caps\n- https://go.dev/wiki/CodeReviewComments#initialisms\n- https://go.dev/wiki/CodeReviewComments#variable-names\n\nAvailable since\n    2019.1, non-default\n\nOptions\n    initialisms\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1005\"",
							"Doc": "Incorrectly formatted error string\n\nError strings follow a set of guidelines to ensure uniformity and good\ncomposability.\n\nQuoting Go Code Review Comments:\n\n\u003e Error strings should not be capitalized (unless beginning with\n\u003e proper nouns or acronyms) or end with punctuation, since they are\n\u003e usually printed following other context. That is, use\n\u003e fmt.Errorf(\"something bad\") not fmt.Errorf(\"Something bad\"), so\n\u003e that log.Printf(\"Reading %s: %v\", filename, err) formats without a\n\u003e spurious capital letter mid-message.\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1006\"",
							"Doc": "Poorly chosen receiver name\n\nQuoting Go Code Review Comments:\n\n\u003e The name of a method's receiver should be a reflection of its\n\u003e identity; often a one or two letter abbreviation of its type\n\u003e suffices (such as \"c\" or \"cl\" for \"Client\"). Don't use generic\n\u003e names such as \"me\", \"this\" or \"self\", identifiers typical of\n\u003e object-oriented languages that place more emphasis on methods as\n\u003e opposed to functions. The name need not be as descriptive as that\n\u003e of a method argument, as its role is obvious and serves no\n\u003e documentary purpose. It can be very short as it will appear on\n\u003e almost every line of every method of the type; familiarity admits\n\u003e brevity. Be consistent, too: if you call the receiver \"c\" in one\n\u003e method, don't call it \"cl\" in another.\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1008\"",
							"Doc": "A function's error value should be its last return value\n\nA function's error value should be its last return value.\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1011\"",
							"Doc": "Poorly chosen name for variable of type time.Duration\n\ntime.Duration values represent an amount of time, which is represented\nas a count of nanoseconds. An expression like 5 * time.Microsecond\nyields the value 5000. It is therefore not appropriate to suffix a\nvariable of type time.Duration with any time unit, such as Msec or\nMilli.\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1012\"",
							"Doc": "Poorly chosen name for error variable\n\nError variables that are part of an API should be called errFoo or\nErrFoo.\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1013\"",
							"Doc": "Should use constants for HTTP error codes, not magic numbers\n\nHTTP has a tremendous number of status codes. While some of those are\nwell known (200, 400, 404, 500), most of them are not. The net/http\npackage provides constants for all status codes that are part of the\nvarious specifications. It is recommended to use these constants\ninstead of hard-coding magic numbers, to vastly improve the\nreadability of your code.\n\nAvailable since\n    2019.1\n\nOptions\n    http_status_code_whitelist\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1015\"",
							"Doc": "A switch's default case should be the first or last case\n\nAvailable since\n    2019.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1016\"",
							"Doc": "Use consistent method receiver names\n\nAvailable since\n    2019.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1017\"",
							"Doc": "Don't use Yoda conditions\n\nYoda conditions are conditions of the kind 'if 42 == x', where the\nliteral is on the left side of the comparison. These are a common\nidiom in languages in which assignment is an expression, to avoid bugs\nof the kind 'if (x = 42)'. In Go, which doesn't allow for this kind of\nbug, we prefer the more idiomatic 'if x == 42'.\n\nAvailable since\n    2019.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1018\"",
							"Doc": "Avoid zero-width and control characters in string literals\n\nAvailable since\n    2019.2\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1019\"",
							"Doc": "Importing the same package multiple times\n\nGo allows importing the same package multiple times, as long as\ndifferent import aliases are being used. That is, the following\nbit of code is valid:\n\n    import (\n        \"fmt\"\n        fumpt \"fmt\"\n        format \"fmt\"\n    )\n\nHowever, this is very rarely done on purpose. Usually, it is a\nsign of code that got refactored, accidentally adding duplicate\nimport statements. It is also a rarely known feature, which may\ncontribute to confusion.\n\nDo note that sometimes, this feature may be used\nintentionally (see for example\nhttps://github.com/golang/go/commit/3409ce39bfd7584523b7a8c150a310cea92d879d)\n– if you want to allow this pattern in your code base, you're\nadvised to disable this check.\n\nIt is acceptable to import the same package twice if one of the imports\nuses the blank identifier. This is allowed in order to increase\nresilience against erroneous changes when using the same package for its\nside effects as well as its exported API.\n\nAvailable since\n    2020.1\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1020\"",
							"Doc": "The documentation of an exported function should start with the function's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1021\"",
							"Doc": "The documentation of an exported type should start with type's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1022\"",
							"Doc": "The documentation of an exported variable or constant should start with variable's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ST1023\"",
							"Doc": "Redundant type in variable declaration\n\nAvailable since\n    2021.1, non-default\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"any\"",
							"Doc": "replace interface{} with any\n\nThe any analyzer suggests replacing uses of the empty interface type,\n`interface{}`, with the `any` alias, which was introduced in Go 1.18.\nThis is a purely stylistic change that makes code more readable.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"appendclipped\"",
							"Doc": "simplify append chains using slices.Concat\n\nThe appendclipped analyzer suggests replacing chains of append calls with a\nsingle call to slices.Concat, which was added in Go 1.21. For example,\nappend(append(s, s1...), s2...) would be simplified to slices.Concat(s, s1, s2).\n\nIn the simple case of appending to a newly allocated slice, such as\nappend([]T(nil), s...), the analyzer suggests the more concise slices.Clone(s).\nFor byte slices, it will prefer bytes.Clone if the \"bytes\" package is\nalready imported.\n\nThis fix is only applied when the base of the append tower is a\n\"clipped\" slice, meaning its length and capacity are equal (e.g.\nx[:0:0] or []T{}). This is to avoid changing program behavior by\neliminating intended side effects on the base slice's underlying\narray.\n\nThis analyzer is currently disabled by default as the\ntransformation does not preserve the nilness of the base slice in\nall cases; see https://go.dev/issue/73557.",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"appends\"",
							"Doc": "check for missing values after append\n\nThis checker reports calls to append that pass\nno values to be appended to the slice.\n\n\ts := []string{\"a\", \"b\", \"c\"}\n\t_ = append(s)\n\nSuch calls are always no-ops and often indicate an\nunderlying mistake.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"asmdecl\"",
							"Doc": "report mismatches between assembly files and Go declarations",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"assign\"",
							"Doc": "check for useless assignments\n\nThis checker reports assignments of the form x = x or a[i] = a[i].\nThese are almost always useless, and even when they aren't they are\nusually a mistake.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"atomic\"",
							"Doc": "check for common mistakes using the sync/atomic package\n\nThe atomic checker looks for assignment statements of the form:\n\n\tx = atomic.AddUint64(\u0026x, 1)\n\nwhich are not atomic.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"atomicalign\"",
							"Doc": "check for non-64-bits-aligned arguments to sync/atomic functions",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"atomictypes\"",
							"Doc": "replace basic types in sync/atomic calls with atomic types\n\nThe atomictypes analyzer suggests replacing the primitive sync/atomic functions with\nthe strongly typed atomic wrapper types introduced in Go1.19 (e.g.\natomic.Int32). For example,\n\n\tvar x int32\n\tatomic.AddInt32(\u0026x, 1)\n\nwould become\n\n\tvar x atomic.Int32\n\tx.Add(1)\n\nThe atomic types are safer because they don't allow non-atomic access, which is\na common source of bugs. These types also resolve memory alignment issues that\nplagued the old atomic functions on 32-bit architectures.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"bloop\"",
							"Doc": "replace for-range over b.N with b.Loop\n\nThe bloop analyzer suggests replacing benchmark loops of the form\n`for i := 0; i \u003c b.N; i++` or `for range b.N` with the more modern\n`for b.Loop()`, which was added in Go 1.24.\n\nThis change makes benchmark code more readable and also removes the need for\nmanual timer control, so any preceding calls to b.StartTimer, b.StopTimer,\nor b.ResetTimer within the same function will also be removed.\n\nCaveats: The b.Loop() method is designed to prevent the compiler from\noptimizing away the benchmark loop, which can occasionally result in\nslower execution due to increased allocations in some specific cases.\nSince its fix may change the performance of nanosecond-scale benchmarks,\nbloop is disabled by default in the `go fix` analyzer suite; see golang/go#74967.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"bools\"",
							"Doc": "check for common mistakes involving boolean operators",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"buildtag\"",
							"Doc": "check //go:build and // +build directives",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"cgocall\"",
							"Doc": "detect some violations of the cgo pointer passing rules\n\nCheck for invalid cgo pointer passing.\nThis looks for code that uses cgo to call C code passing values\nwhose types are almost always invalid according to the cgo pointer\nsharing rules.\nSpecifically, it warns about attempts to pass a Go chan, map, func,\nor slice to C, either directly, or via a pointer, array, or struct.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"composites\"",
							"Doc": "check for unkeyed composite literals\n\nThis analyzer reports a diagnostic for composite literals of struct\ntypes imported from another package that do not use the field-keyed\nsyntax. Such literals are fragile because the addition of a new field\n(even if unexported) to the struct will cause compilation to fail.\n\nAs an example,\n\n\terr = \u0026net.DNSConfigError{err}\n\nshould be replaced by:\n\n\terr = \u0026net.DNSConfigError{Err: err}\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"copylocks\"",
							"Doc": "check for locks erroneously passed by value\n\nInadvertently copying a value containing a lock, such as sync.Mutex or\nsync.WaitGroup, may cause both copies to malfunction. Generally such\nvalues should be referred to through a pointer.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"deepequalerrors\"",
							"Doc": "check for calls of reflect.DeepEqual on error values\n\nThe deepequalerrors checker looks for calls of the form:\n\n    reflect.DeepEqual(err1, err2)\n\nwhere err1 and err2 are errors. Using reflect.DeepEqual to compare\nerrors is discouraged.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"defers\"",
							"Doc": "report common mistakes in defer statements\n\nThe defers analyzer reports a diagnostic when a defer statement would\nresult in a non-deferred call to time.Since, as experience has shown\nthat this is nearly always a mistake.\n\nFor example:\n\n\tstart := time.Now()\n\t...\n\tdefer recordLatency(time.Since(start)) // error: call to time.Since is not deferred\n\nThe correct code is:\n\n\tdefer func() { recordLatency(time.Since(start)) }()",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"deprecated\"",
							"Doc": "check for use of deprecated identifiers\n\nThe deprecated analyzer looks for deprecated symbols and package\nimports.\n\nSee https://go.dev/wiki/Deprecated to learn about Go's convention\nfor documenting and signaling deprecated identifiers.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"directive\"",
							"Doc": "check Go toolchain directives such as //go:debug\n\nThis analyzer checks for problems with known Go toolchain directives\nin all Go source files in a package directory, even those excluded by\n//go:build constraints, and all non-Go source files too.\n\nFor //go:debug (see https://go.dev/doc/godebug), the analyzer checks\nthat the directives are placed only in Go source files, only above the\npackage comment, and only in package main or *_test.go files.\n\nSupport for other known directives may be added in the future.\n\nThis analyzer does not check //go:build, which is handled by the\nbuildtag analyzer.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"embed\"",
							"Doc": "check //go:embed directive usage\n\nThis analyzer checks that the embed package is imported if //go:embed\ndirectives are present, providing a suggested fix to add the import if\nit is missing.\n\nThis analyzer also checks that //go:embed directives precede the\ndeclaration of a single variable.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"errorsas\"",
							"Doc": "report passing non-pointer or non-error values to errors.As\n\nThe errorsas analyzer reports calls to errors.As where the type\nof the second argument is not a pointer to a type implementing error.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"errorsastype\"",
							"Doc": "replace errors.As with errors.AsType[T]\n\nThis analyzer suggests fixes to simplify uses of [errors.As] of\nthis form:\n\n\tvar myerr *MyErr\n\tif errors.As(err, \u0026myerr) {\n\t\thandle(myerr)\n\t}\n\nby using the less error-prone generic [errors.AsType] function,\nintroduced in Go 1.26:\n\n\tif myerr, ok := errors.AsType[*MyErr](err); ok {\n\t\thandle(myerr)\n\t}\n\nThe fix is only offered if the var declaration has the form shown and\nthere are no uses of myerr outside the if statement.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"fieldalignment\"",
							"Doc": "find structs that would use less memory if their fields were sorted\n\nThis analyzer finds structs that can be rearranged to use less memory, and provides\na suggested edit with the most compact order.\n\nNote that there are two different diagnostics reported. One checks struct size,\nand the other reports \"pointer bytes\" used. Pointer bytes is how many bytes of the\nobject that the garbage collector has to potentially scan for pointers, for example:\n\n\tstruct { uint32; string }\n\nhave 16 pointer bytes because the garbage collector has to scan up through the string's\ninner pointer.\n\n\tstruct { string; *uint32 }\n\nhas 24 pointer bytes because it has to scan further through the *uint32.\n\n\tstruct { string; uint32 }\n\nhas 8 because it can stop immediately after the string pointer.\n\nBe aware that the most compact order is not always the most efficient.\nIn rare cases it may cause two variables each updated by its own goroutine\nto occupy the same CPU cache line, inducing a form of memory contention\nknown as \"false sharing\" that slows down both goroutines.\n\nUnlike most analyzers, which report likely mistakes, the diagnostics\nproduced by fieldanalyzer very rarely indicate a significant problem,\nso the analyzer is not included in typical suites such as vet or\ngopls. Use this standalone command to run it on your code:\n\n   $ go install golang.org/x/tools/go/analysis/passes/fieldalignment/cmd/fieldalignment@latest\n   $ fieldalignment [packages]\n\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"fillreturns\"",
							"Doc": "suggest fixes for errors due to an incorrect number of return values\n\nThis checker provides suggested fixes for type errors of the\ntype \"wrong number of return values (want %d, got %d)\". For example:\n\n\tfunc m() (int, string, *bool, error) {\n\t\treturn\n\t}\n\nwill turn into\n\n\tfunc m() (int, string, *bool, error) {\n\t\treturn 0, \"\", nil, nil\n\t}\n\nThis functionality is similar to https://github.com/sqs/goreturns.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"fmtappendf\"",
							"Doc": "replace []byte(fmt.Sprintf) with fmt.Appendf\n\nThe fmtappendf analyzer suggests replacing `[]byte(fmt.Sprintf(...))` with\n`fmt.Appendf(nil, ...)`. This avoids the intermediate allocation of a string\nby Sprintf, making the code more efficient. The suggestion also applies to\nfmt.Sprint and fmt.Sprintln.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"forvar\"",
							"Doc": "remove redundant re-declaration of loop variables\n\nThe forvar analyzer removes unnecessary shadowing of loop variables.\nBefore Go 1.22, it was common to write `for _, x := range s { x := x ... }`\nto create a fresh variable for each iteration. Go 1.22 changed the semantics\nof `for` loops, making this pattern redundant. This analyzer removes the\nunnecessary `x := x` statement.\n\nThis fix only applies to `range` loops.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"framepointer\"",
							"Doc": "report assembly that clobbers the frame pointer before saving it",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"hostport\"",
							"Doc": "check format of addresses passed to net.Dial\n\nThis analyzer flags code that produce network address strings using\nfmt.Sprintf, as in this example:\n\n    addr := fmt.Sprintf(\"%s:%d\", host, 12345) // \"will not work with IPv6\"\n    ...\n    conn, err := net.Dial(\"tcp\", addr)       // \"when passed to dial here\"\n\nThe analyzer suggests a fix to use the correct approach, a call to\nnet.JoinHostPort:\n\n    addr := net.JoinHostPort(host, \"12345\")\n    ...\n    conn, err := net.Dial(\"tcp\", addr)\n\nA similar diagnostic and fix are produced for a format string of \"%s:%s\".\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"httpresponse\"",
							"Doc": "check for mistakes using HTTP responses\n\nA common mistake when using the net/http package is to defer a function\ncall to close the http.Response Body before checking the error that\ndetermines whether the response is valid:\n\n\tresp, err := http.Head(url)\n\tdefer resp.Body.Close()\n\tif err != nil {\n\t\tlog.Fatal(err)\n\t}\n\t// (defer statement belongs here)\n\nThis checker helps uncover latent nil dereference bugs by reporting a\ndiagnostic for such mistakes.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"ifaceassert\"",
							"Doc": "detect impossible interface-to-interface type assertions\n\nThis checker flags type assertions v.(T) and corresponding type-switch cases\nin which the static type V of v is an interface that cannot possibly implement\nthe target interface T. This occurs when V and T contain methods with the same\nname but different signatures. Example:\n\n\tvar v interface {\n\t\tRead()\n\t}\n\t_ = v.(io.Reader)\n\nThe Read method in v has a different signature than the Read method in\nio.Reader, so this assertion cannot succeed.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"infertypeargs\"",
							"Doc": "check for unnecessary type arguments in call expressions\n\nExplicit type arguments may be omitted from call expressions if they can be\ninferred from function arguments, or from other type arguments:\n\n\tfunc f[T any](T) {}\n\t\n\tfunc _() {\n\t\tf[string](\"foo\") // string could be inferred\n\t}\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"inline\"",
							"Doc": "apply fixes based on 'go:fix inline' comment directives\n\nThe inline analyzer inlines functions and constants that are marked for inlining.\n\n## Functions\n\nGiven a function that is marked for inlining, like this one:\n\n\t//go:fix inline\n\tfunc Square(x int) int { return Pow(x, 2) }\n\nthis analyzer will recommend that calls to the function elsewhere, in the same\nor other packages, should be inlined.\n\nInlining can be used to move off of a deprecated function:\n\n\t// Deprecated: prefer Pow(x, 2).\n\t//go:fix inline\n\tfunc Square(x int) int { return Pow(x, 2) }\n\nIt can also be used to move off of an obsolete package,\nas when the import path has changed or a higher major version is available:\n\n\tpackage pkg\n\n\timport pkg2 \"pkg/v2\"\n\n\t//go:fix inline\n\tfunc F() { pkg2.F(nil) }\n\nReplacing a call pkg.F() by pkg2.F(nil) can have no effect on the program,\nso this mechanism provides a low-risk way to update large numbers of calls.\nWe recommend, where possible, expressing the old API in terms of the new one\nto enable automatic migration.\n\nThe inliner takes care to avoid behavior changes, even subtle ones,\nsuch as changes to the order in which argument expressions are\nevaluated. When it cannot safely eliminate all parameter variables,\nit may introduce a \"binding declaration\" of the form\n\n\tvar params = args\n\nto evaluate argument expressions in the correct order and bind them to\nparameter variables. Since the resulting code transformation may be\nstylistically suboptimal, such inlinings may be disabled by specifying\nthe -inline.allow_binding_decl=false flag to the analyzer driver.\n\n(In cases where it is not safe to \"reduce\" a call—that is, to replace\na call f(x) by the body of function f, suitably substituted—the\ninliner machinery is capable of replacing f by a function literal,\nfunc(){...}(). However, the inline analyzer discards all such\n\"literalizations\" unconditionally, again on grounds of style.)\n\n## Constants\n\nGiven a constant that is marked for inlining, like this one:\n\n\t//go:fix inline\n\tconst Ptr = Pointer\n\nthis analyzer will recommend that uses of Ptr should be replaced with Pointer.\n\nAs with functions, inlining can be used to replace deprecated constants and\nconstants in obsolete packages.\n\nA constant definition can be marked for inlining only if it refers to another\nnamed constant.\n\nThe \"//go:fix inline\" comment must appear before a single const declaration on its own,\nas above; before a const declaration that is part of a group, as in this case:\n\n\tconst (\n\t   C = 1\n\t   //go:fix inline\n\t   Ptr = Pointer\n\t)\n\nor before a group, applying to every constant in the group:\n\n\t//go:fix inline\n\tconst (\n\t\tPtr = Pointer\n\t    Val = Value\n\t)\n\nThe proposal https://go.dev/issue/32816 introduces the \"//go:fix inline\" directives.\n\nYou can use this command to apply inline fixes en masse:\n\n\t$ go run golang.org/x/tools/go/analysis/passes/inline/cmd/inline@latest -fix ./...",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"loopclosure\"",
							"Doc": "check references to loop variables from within nested functions\n\nThis analyzer reports places where a function literal references the\niteration variable of an enclosing loop, and the loop calls the function\nin such a way (e.g. with go or defer) that it may outlive the loop\niteration and possibly observe the wrong value of the variable.\n\nNote: An iteration variable can only outlive a loop iteration in Go versions \u003c=1.21.\nIn Go 1.22 and later, the loop variable lifetimes changed to create a new\niteration variable per loop iteration. (See go.dev/issue/60078.)\n\nIn this example, all the deferred functions run after the loop has\ncompleted, so all observe the final value of v [\u003cgo1.22].\n\n\tfor _, v := range list {\n\t    defer func() {\n\t        use(v) // incorrect\n\t    }()\n\t}\n\nOne fix is to create a new variable for each iteration of the loop:\n\n\tfor _, v := range list {\n\t    v := v // new var per iteration\n\t    defer func() {\n\t        use(v) // ok\n\t    }()\n\t}\n\nAfter Go version 1.22, the previous two for loops are equivalent\nand both are correct.\n\nThe next example uses a go statement and has a similar problem [\u003cgo1.22].\nIn addition, it has a data race because the loop updates v\nconcurrent with the goroutines accessing it.\n\n\tfor _, v := range elem {\n\t    go func() {\n\t        use(v)  // incorrect, and a data race\n\t    }()\n\t}\n\nA fix is the same as before. The checker also reports problems\nin goroutines started by golang.org/x/sync/errgroup.Group.\nA hard-to-spot variant of this form is common in parallel tests:\n\n\tfunc Test(t *testing.T) {\n\t    for _, test := range tests {\n\t        t.Run(test.name, func(t *testing.T) {\n\t            t.Parallel()\n\t            use(test) // incorrect, and a data race\n\t        })\n\t    }\n\t}\n\nThe t.Parallel() call causes the rest of the function to execute\nconcurrent with the loop [\u003cgo1.22].\n\nThe analyzer reports references only in the last statement,\nas it is not deep enough to understand the effects of subsequent\nstatements that might render the reference benign.\n(\"Last statement\" is defined recursively in compound\nstatements such as if, switch, and select.)\n\nSee: https://golang.org/doc/go_faq.html#closures_and_goroutines",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"lostcancel\"",
							"Doc": "check cancel func returned by context.WithCancel is called\n\nThe cancellation function returned by context.WithCancel, WithTimeout,\nWithDeadline and variants such as WithCancelCause must be called,\nor the new context will remain live until its parent context is cancelled.\n(The background context is never cancelled.)",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"maprange\"",
							"Doc": "checks for unnecessary calls to maps.Keys and maps.Values in range statements\n\nConsider a loop written like this:\n\n\tfor val := range maps.Values(m) {\n\t\tfmt.Println(val)\n\t}\n\nThis should instead be written without the call to maps.Values:\n\n\tfor _, val := range m {\n\t\tfmt.Println(val)\n\t}\n\ngolang.org/x/exp/maps returns slices for Keys/Values instead of iterators,\nbut unnecessary calls should similarly be removed:\n\n\tfor _, key := range maps.Keys(m) {\n\t\tfmt.Println(key)\n\t}\n\nshould be rewritten as:\n\n\tfor key := range m {\n\t\tfmt.Println(key)\n\t}",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"mapsloop\"",
							"Doc": "replace explicit loops over maps with calls to maps package\n\nThe mapsloop analyzer replaces loops of the form\n\n\tfor k, v := range x { m[k] = v }\n\nwith a single call to a function from the `maps` package, added in Go 1.23.\nDepending on the context, this could be `maps.Copy`, `maps.Insert`,\n`maps.Clone`, or `maps.Collect`.\n\nThe transformation to `maps.Clone` is applied conservatively, as it\npreserves the nilness of the source map, which may be a subtle change in\nbehavior if the original code did not handle a nil map in the same way.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"minmax\"",
							"Doc": "replace if/else statements with calls to min or max\n\nThe minmax analyzer simplifies conditional assignments by suggesting the use\nof the built-in `min` and `max` functions, introduced in Go 1.21. For example,\n\n\tif a \u003c b { x = a } else { x = b }\n\nis replaced by\n\n\tx = min(a, b).\n\nThis analyzer avoids making suggestions for floating-point types,\nas the behavior of `min` and `max` with NaN values can differ from\nthe original if/else statement.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"newexpr\"",
							"Doc": "simplify code by using go1.26's new(expr)\n\nThis analyzer finds declarations of functions of this form:\n\n\tfunc varOf(x int) *int { return \u0026x }\n\nand suggests a fix to turn them into inlinable wrappers around\ngo1.26's built-in new(expr) function:\n\n\t//go:fix inline\n\tfunc varOf(x int) *int { return new(x) }\n\n(The directive comment causes the 'inline' analyzer to suggest\nthat calls to such functions are inlined.)\n\nIn addition, this analyzer suggests a fix for each call\nto one of the functions before it is transformed, so that\n\n\tuse(varOf(123))\n\nis replaced by:\n\n\tuse(new(123))\n\nWrapper functions such as varOf are common when working with Go\nserialization packages such as for JSON or protobuf, where pointers\nare often used to express optionality.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"nilfunc\"",
							"Doc": "check for useless comparisons between functions and nil\n\nA useless comparison is one like f == nil as opposed to f() == nil.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"nilness\"",
							"Doc": "check for redundant or impossible nil comparisons\n\nThe nilness checker inspects the control-flow graph of each function in\na package and reports nil pointer dereferences, degenerate nil\npointers, and panics with nil values. A degenerate comparison is of the form\nx==nil or x!=nil where x is statically known to be nil or non-nil. These are\noften a mistake, especially in control flow related to errors. Panics with nil\nvalues are checked because they are not detectable by\n\n\tif r := recover(); r != nil {\n\nThis check reports conditions such as:\n\n\tif f == nil { // impossible condition (f is a function)\n\t}\n\nand:\n\n\tp := \u0026v\n\t...\n\tif p != nil { // tautological condition\n\t}\n\nand:\n\n\tif p == nil {\n\t\tprint(*p) // nil dereference\n\t}\n\nand:\n\n\tif p == nil {\n\t\tpanic(p)\n\t}\n\nSometimes the control flow may be quite complex, making bugs hard\nto spot. In the example below, the err.Error expression is\nguaranteed to panic because, after the first return, err must be\nnil. The intervening loop is just a distraction.\n\n\t...\n\terr := g.Wait()\n\tif err != nil {\n\t\treturn err\n\t}\n\tpartialSuccess := false\n\tfor _, err := range errs {\n\t\tif err == nil {\n\t\t\tpartialSuccess = true\n\t\t\tbreak\n\t\t}\n\t}\n\tif partialSuccess {\n\t\treportStatus(StatusMessage{\n\t\t\tCode:   code.ERROR,\n\t\t\tDetail: err.Error(), // \"nil dereference in dynamic method call\"\n\t\t})\n\t\treturn nil\n\t}\n\n...",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"nonewvars\"",
							"Doc": "suggested fixes for \"no new vars on left side of :=\"\n\nThis checker provides suggested fixes for type errors of the\ntype \"no new vars on left side of :=\". For example:\n\n\tz := 1\n\tz := 2\n\nwill turn into\n\n\tz := 1\n\tz = 2",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"noresultvalues\"",
							"Doc": "suggested fixes for unexpected return values\n\nThis checker provides suggested fixes for type errors of the\ntype \"no result values expected\" or \"too many return values\".\nFor example:\n\n\tfunc z() { return nil }\n\nwill turn into\n\n\tfunc z() { return }",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"omitzero\"",
							"Doc": "suggest replacing omitempty with omitzero for struct fields\n\nThe omitzero analyzer identifies uses of the `omitempty` JSON struct\ntag on fields that are themselves structs. For struct-typed fields,\nthe `omitempty` tag has no effect on the behavior of json.Marshal and\njson.Unmarshal. The analyzer offers two suggestions: either remove the\ntag, or replace it with `omitzero` (added in Go 1.24), which correctly\nomits the field if the struct value is zero.\n\nHowever, some other serialization packages (notably kubebuilder, see\nhttps://book.kubebuilder.io/reference/markers.html) may have their own\ninterpretation of the `json:\",omitzero\"` tag, so removing it may affect\nprogram behavior. For this reason, the omitzero modernizer will not\nmake changes in any package that contains +kubebuilder annotations.\n\nReplacing `omitempty` with `omitzero` is a change in behavior. The\noriginal code would always encode the struct field, whereas the\nmodified code will omit it if it is a zero-value.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"plusbuild\"",
							"Doc": "remove obsolete //+build comments\n\nThe plusbuild analyzer suggests a fix to remove obsolete build tags\nof the form:\n\n\t//+build linux,amd64\n\nin files that also contain a Go 1.18-style tag such as:\n\n\t//go:build linux \u0026\u0026 amd64\n\n(It does not check that the old and new tags are consistent;\nthat is the job of the 'buildtag' analyzer in the vet suite.)",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"printf\"",
							"Doc": "check consistency of Printf format strings and arguments\n\nThe check applies to calls of the formatting functions such as\n[fmt.Printf] and [fmt.Sprintf], as well as any detected wrappers of\nthose functions such as [log.Printf]. It reports a variety of\nmistakes such as syntax errors in the format string and mismatches\n(of number and type) between the verbs and their arguments.\n\nSee the documentation of the fmt package for the complete set of\nformat operators and their operand types.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"rangeint\"",
							"Doc": "replace 3-clause for loops with for-range over integers\n\nThe rangeint analyzer suggests replacing traditional for loops such\nas\n\n\tfor i := 0; i \u003c n; i++ { ... }\n\nwith the more idiomatic Go 1.22 style:\n\n\tfor i := range n { ... }\n\nThis transformation is applied only if (a) the loop variable is not\nmodified within the loop body and (b) the loop's limit expression\nis not modified within the loop, as `for range` evaluates its\noperand only once.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"recursiveiter\"",
							"Doc": "check for inefficient recursive iterators\n\nThis analyzer reports when a function that returns an iterator\n(iter.Seq or iter.Seq2) calls itself as the operand of a range\nstatement, as this is inefficient.\n\nWhen implementing an iterator (e.g. iter.Seq[T]) for a recursive\ndata type such as a tree or linked list, it is tempting to\nrecursively range over the iterator for each child element.\n\nHere's an example of a naive iterator over a binary tree:\n\n\ttype tree struct {\n\t\tvalue       int\n\t\tleft, right *tree\n\t}\n\n\tfunc (t *tree) All() iter.Seq[int] {\n\t\treturn func(yield func(int) bool) {\n\t\t\tif t != nil {\n\t\t\t\tfor elem := range t.left.All() { // \"inefficient recursive iterator\"\n\t\t\t\t\tif !yield(elem) {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tif !yield(t.value) {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tfor elem := range t.right.All() { // \"inefficient recursive iterator\"\n\t\t\t\t\tif !yield(elem) {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\nThough it correctly enumerates the elements of the tree, it hides a\nsignificant performance problem--two, in fact. Consider a balanced\ntree of N nodes. Iterating the root node will cause All to be\ncalled once on every node of the tree. This results in a chain of\nnested active range-over-func statements when yield(t.value) is\ncalled on a leaf node.\n\nThe first performance problem is that each range-over-func\nstatement must typically heap-allocate a variable, so iteration of\nthe tree allocates as many variables as there are elements in the\ntree, for a total of O(N) allocations, all unnecessary.\n\nThe second problem is that each call to yield for a leaf of the\ntree causes each of the enclosing range loops to receive a value,\nwhich they then immediately pass on to their respective yield\nfunction. This results in a chain of log(N) dynamic yield calls per\nelement, a total of O(N*log N) dynamic calls overall, when only\nO(N) are necessary.\n\nA better implementation strategy for recursive iterators is to\nfirst define the \"every\" operator for your recursive data type,\nwhere every(f) reports whether an arbitrary predicate f(x) is true\nfor every element x in the data type. For our tree, the every\nfunction would be:\n\n\tfunc (t *tree) every(f func(int) bool) bool {\n\t\treturn t == nil ||\n\t\t\tt.left.every(f) \u0026\u0026 f(t.value) \u0026\u0026 t.right.every(f)\n\t}\n\nFor example, this use of the every operator prints whether every\nelement in the tree is an even number:\n\n\teven := func(x int) bool { return x\u00261 == 0 }\n\tprintln(t.every(even))\n\nThen the iterator can be simply expressed as a trivial wrapper\naround the every operator:\n\n\tfunc (t *tree) All() iter.Seq[int] {\n\t\treturn func(yield func(int) bool) {\n\t\t\t_ = t.every(yield)\n\t\t}\n\t}\n\nIn effect, tree.All computes whether yield returns true for each\nelement, short-circuiting if it ever returns false, then discards\nthe final boolean result.\n\nThis has much better performance characteristics: it makes one\ndynamic call per element of the tree, and it doesn't heap-allocate\nanything. It is also clearer.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"reflecttypefor\"",
							"Doc": "replace reflect.TypeOf(x) with TypeFor[T]()\n\nThis analyzer suggests fixes to replace uses of reflect.TypeOf(x) with\nreflect.TypeFor, introduced in go1.22, when the desired runtime type\nis known at compile time, for example:\n\n\treflect.TypeOf(uint32(0))        -\u003e reflect.TypeFor[uint32]()\n\treflect.TypeOf((*ast.File)(nil)) -\u003e reflect.TypeFor[*ast.File]()\n\nIt also offers a fix to simplify the constructions below, which use\nreflect.TypeOf to return the runtime type for an interface type,\n\n\treflect.TypeOf((*io.Reader)(nil)).Elem()\n\nor:\n\n\treflect.TypeOf([]io.Reader(nil)).Elem()\n\nto:\n\n\treflect.TypeFor[io.Reader]()\n\nNo fix is offered in cases when the runtime type is dynamic, such as:\n\n\tvar r io.Reader = ...\n\treflect.TypeOf(r)\n\nor when the operand has potential side effects.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"shadow\"",
							"Doc": "check for possible unintended shadowing of variables\n\nThis analyzer check for shadowed variables.\nA shadowed variable is a variable declared in an inner scope\nwith the same name and type as a variable in an outer scope,\nand where the outer variable is mentioned after the inner one\nis declared.\n\n(This definition can be refined; the module generates too many\nfalse positives and is not yet enabled by default.)\n\nFor example:\n\n\tfunc BadRead(f *os.File, buf []byte) error {\n\t\tvar err error\n\t\tfor {\n\t\t\tn, err := f.Read(buf) // shadows the function variable 'err'\n\t\t\tif err != nil {\n\t\t\t\tbreak // causes return of wrong value\n\t\t\t}\n\t\t\tfoo(buf)\n\t\t}\n\t\treturn err\n\t}",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"shift\"",
							"Doc": "check for shifts that equal or exceed the width of the integer",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"sigchanyzer\"",
							"Doc": "check for unbuffered channel of os.Signal\n\nThis checker reports call expression of the form\n\n\tsignal.Notify(c \u003c-chan os.Signal, sig ...os.Signal),\n\nwhere c is an unbuffered channel, which can be at risk of missing the signal.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"simplifycompositelit\"",
							"Doc": "check for composite literal simplifications\n\nAn array, slice, or map composite literal of the form:\n\n\t[]T{T{}, T{}}\n\nwill be simplified to:\n\n\t[]T{{}, {}}\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"simplifyrange\"",
							"Doc": "check for range statement simplifications\n\nA range of the form:\n\n\tfor x, _ = range v {...}\n\nwill be simplified to:\n\n\tfor x = range v {...}\n\nA range of the form:\n\n\tfor _ = range v {...}\n\nwill be simplified to:\n\n\tfor range v {...}\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"simplifyslice\"",
							"Doc": "check for slice simplifications\n\nA slice expression of the form:\n\n\ts[a:len(s)]\n\nwill be simplified to:\n\n\ts[a:]\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"slicescontains\"",
							"Doc": "replace loops with slices.Contains or slices.ContainsFunc\n\nThe slicescontains analyzer simplifies loops that check for the existence of\nan element in a slice. It replaces them with calls to `slices.Contains` or\n`slices.ContainsFunc`, which were added in Go 1.21.\n\nIf the expression for the target element has side effects, this\ntransformation will cause those effects to occur only once, not\nonce per tested slice element.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"slicesdelete\"",
							"Doc": "replace append-based slice deletion with slices.Delete\n\nThe slicesdelete analyzer suggests replacing the idiom\n\n\ts = append(s[:i], s[j:]...)\n\nwith the more explicit\n\n\ts = slices.Delete(s, i, j)\n\nintroduced in Go 1.21.\n\nThis analyzer is disabled by default. The `slices.Delete` function\nzeros the elements between the new length and the old length of the\nslice to prevent memory leaks, which is a subtle difference in\nbehavior compared to the append-based idiom; see https://go.dev/issue/73686.",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"slicessort\"",
							"Doc": "replace sort.Slice with slices.Sort for basic types\n\nThe slicessort analyzer simplifies sorting slices of basic ordered\ntypes. It replaces\n\n\tsort.Slice(s, func(i, j int) bool { return s[i] \u003c s[j] })\n\nwith the simpler `slices.Sort(s)`, which was added in Go 1.21.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"slog\"",
							"Doc": "check for invalid structured logging calls\n\nThe slog checker looks for calls to functions from the log/slog\npackage that take alternating key-value pairs. It reports calls\nwhere an argument in a key position is neither a string nor a\nslog.Attr, and where a final key is missing its value.\nFor example,it would report\n\n\tslog.Warn(\"message\", 11, \"k\") // slog.Warn arg \"11\" should be a string or a slog.Attr\n\nand\n\n\tslog.Info(\"message\", \"k1\", v1, \"k2\") // call to slog.Info missing a final value",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"sortslice\"",
							"Doc": "check the argument type of sort.Slice\n\nsort.Slice requires an argument of a slice type. Check that\nthe interface{} value passed to sort.Slice is actually a slice.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stditerators\"",
							"Doc": "use iterators instead of Len/At-style APIs\n\nThis analyzer suggests a fix to replace each loop of the form:\n\n\tfor i := 0; i \u003c x.Len(); i++ {\n\t\tuse(x.At(i))\n\t}\n\nor its \"for elem := range x.Len()\" equivalent by a range loop over an\niterator offered by the same data type:\n\n\tfor elem := range x.All() {\n\t\tuse(x.At(i)\n\t}\n\nwhere x is one of various well-known types in the standard library.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stdmethods\"",
							"Doc": "check signature of methods of well-known interfaces\n\nSometimes a type may be intended to satisfy an interface but may fail to\ndo so because of a mistake in its method signature.\nFor example, the result of this WriteTo method should be (int64, error),\nnot error, to satisfy io.WriterTo:\n\n\ttype myWriterTo struct{...}\n\tfunc (myWriterTo) WriteTo(w io.Writer) error { ... }\n\nThis check ensures that each method whose name matches one of several\nwell-known interface methods from the standard library has the correct\nsignature for that interface.\n\nChecked method names include:\n\n\tFormat GobEncode GobDecode MarshalJSON MarshalXML\n\tPeek ReadByte ReadFrom ReadRune Scan Seek\n\tUnmarshalJSON UnreadByte UnreadRune WriteByte\n\tWriteTo",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stdversion\"",
							"Doc": "report uses of too-new standard library symbols\n\nThe stdversion analyzer reports references to symbols in the standard\nlibrary that were introduced by a Go release higher than the one in\nforce in the referring file. (Recall that the file's Go version is\ndefined by the 'go' directive its module's go.mod file, or by a\n\"//go:build go1.X\" build tag at the top of the file.)\n\nThe analyzer does not report a diagnostic for a reference to a \"too\nnew\" field or method of a type that is itself \"too new\", as this may\nhave false positives, for example if fields or methods are accessed\nthrough a type alias that is guarded by a Go version constraint.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stringintconv\"",
							"Doc": "check for string(int) conversions\n\nThis checker flags conversions of the form string(x) where x is an integer\n(but not byte or rune) type. Such conversions are discouraged because they\nreturn the UTF-8 representation of the Unicode code point x, and not a decimal\nstring representation of x as one might expect. Furthermore, if x denotes an\ninvalid code point, the conversion cannot be statically rejected.\n\nFor conversions that intend on using the code point, consider replacing them\nwith string(rune(x)). Otherwise, strconv.Itoa and its equivalents return the\nstring representation of the value in the desired base.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stringsbuilder\"",
							"Doc": "replace += with strings.Builder\n\nThis analyzer replaces repeated string += string concatenation\noperations with calls to Go 1.10's strings.Builder.\n\nFor example:\n\n\tvar s = \"[\"\n\tfor x := range seq {\n\t\ts += x\n\t\ts += \".\"\n\t}\n\ts += \"]\"\n\tuse(s)\n\nis replaced by:\n\n\tvar s strings.Builder\n\ts.WriteString(\"[\")\n\tfor x := range seq {\n\t\ts.WriteString(x)\n\t\ts.WriteString(\".\")\n\t}\n\ts.WriteString(\"]\")\n\tuse(s.String())\n\nThis avoids quadratic memory allocation and improves performance.\n\nThe analyzer requires that all references to s before the final uses\nare += operations. To avoid warning about trivial cases, at least one\nmust appear within a loop. The variable s must be a local\nvariable, not a global or parameter.\n\nAll uses of the finished string must come after the last += operation.\nEach such use will be replaced by a call to strings.Builder's String method.\n(These may appear within an intervening loop or function literal, since even\nif s.String() is called repeatedly, it does not allocate memory.)\n\nOften the addend is a call to fmt.Sprintf, as in this example:\n\n\tvar s string\n\tfor x := range seq {\n\t\ts += fmt.Sprintf(\"%v\", x)\n\t}\n\nwhich, once the suggested fix is applied, becomes:\n\n\tvar s strings.Builder\n\tfor x := range seq {\n\t\ts.WriteString(fmt.Sprintf(\"%v\", x))\n\t}\n\nThe WriteString call can be further simplified to the more efficient\nfmt.Fprintf(\u0026s, \"%v\", x), avoiding the allocation of an intermediary.\nHowever, stringsbuilder does not perform this simplification;\nit requires staticcheck analyzer QF1012. (See https://go.dev/issue/76918.)",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stringscut\"",
							"Doc": "replace strings.Index etc. with strings.Cut\n\nThis analyzer replaces certain patterns of use of [strings.Index] and string slicing by [strings.Cut], added in go1.18.\n\nFor example:\n\n\tidx := strings.Index(s, substr)\n\tif idx \u003e= 0 {\n\t    return s[:idx]\n\t}\n\nis replaced by:\n\n\tbefore, _, ok := strings.Cut(s, substr)\n\tif ok {\n\t    return before\n\t}\n\nAnd:\n\n\tidx := strings.Index(s, substr)\n\tif idx \u003e= 0 {\n\t    return\n\t}\n\nis replaced by:\n\n\tfound := strings.Contains(s, substr)\n\tif found {\n\t    return\n\t}\n\nIt also handles variants using [strings.IndexByte] instead of Index, or the bytes package instead of strings.\n\nFixes are offered only in cases in which there are no potential modifications of the idx, s, or substr expressions between their definition and use.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stringscutprefix\"",
							"Doc": "replace HasPrefix/TrimPrefix with CutPrefix\n\nThe stringscutprefix analyzer simplifies a common pattern where code first\nchecks for a prefix with `strings.HasPrefix` and then removes it with\n`strings.TrimPrefix`. It replaces this two-step process with a single call\nto `strings.CutPrefix`, introduced in Go 1.20. The analyzer also handles\nthe equivalent functions in the `bytes` package.\n\nFor example, this input:\n\n\tif strings.HasPrefix(s, prefix) {\n\t    use(strings.TrimPrefix(s, prefix))\n\t}\n\nis fixed to:\n\n\tif after, ok := strings.CutPrefix(s, prefix); ok {\n\t    use(after)\n\t}\n\nThe analyzer also offers fixes to use CutSuffix in a similar way.\nThis input:\n\n\tif strings.HasSuffix(s, suffix) {\n\t    use(strings.TrimSuffix(s, suffix))\n\t}\n\nis fixed to:\n\n\tif before, ok := strings.CutSuffix(s, suffix); ok {\n\t    use(before)\n\t}",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"stringsseq\"",
							"Doc": "replace ranging over Split/Fields with SplitSeq/FieldsSeq\n\nThe stringsseq analyzer improves the efficiency of iterating over substrings.\nIt replaces\n\n\tfor range strings.Split(...)\n\nwith the more efficient\n\n\tfor range strings.SplitSeq(...)\n\nwhich was added in Go 1.24 and avoids allocating a slice for the\nsubstrings. The analyzer also handles strings.Fields and the\nequivalent functions in the bytes package.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"structtag\"",
							"Doc": "check that struct field tags conform to reflect.StructTag.Get\n\nAlso report certain struct tags (json, xml) used with unexported fields.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"testingcontext\"",
							"Doc": "replace context.WithCancel with t.Context in tests\n\nThe testingcontext analyzer simplifies context management in tests. It\nreplaces the manual creation of a cancellable context,\n\n\tctx, cancel := context.WithCancel(context.Background())\n\tdefer cancel()\n\nwith a single call to t.Context(), which was added in Go 1.24.\n\nThis change is only suggested if the `cancel` function is not used\nfor any other purpose.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"testinggoroutine\"",
							"Doc": "report calls to (*testing.T).Fatal from goroutines started by a test\n\nFunctions that abruptly terminate a test, such as the Fatal, Fatalf, FailNow, and\nSkip{,f,Now} methods of *testing.T, must be called from the test goroutine itself.\nThis checker detects calls to these functions that occur within a goroutine\nstarted by the test. For example:\n\n\tfunc TestFoo(t *testing.T) {\n\t    go func() {\n\t        t.Fatal(\"oops\") // error: (*T).Fatal called from non-test goroutine\n\t    }()\n\t}",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"tests\"",
							"Doc": "check for common mistaken usages of tests and examples\n\nThe tests checker walks Test, Benchmark, Fuzzing and Example functions checking\nmalformed names, wrong signatures and examples documenting non-existent\nidentifiers.\n\nPlease see the documentation for package testing in golang.org/pkg/testing\nfor the conventions that are enforced for Tests, Benchmarks, and Examples.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"timeformat\"",
							"Doc": "check for calls of (time.Time).Format or time.Parse with 2006-02-01\n\nThe timeformat checker looks for time formats with the 2006-02-01 (yyyy-dd-mm)\nformat. Internationally, \"yyyy-dd-mm\" does not occur in common calendar date\nstandards, and so it is more likely that 2006-01-02 (yyyy-mm-dd) was intended.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unmarshal\"",
							"Doc": "report passing non-pointer or non-interface values to unmarshal\n\nThe unmarshal analysis reports calls to functions such as json.Unmarshal\nin which the argument type is not a pointer or an interface.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unreachable\"",
							"Doc": "check for unreachable code\n\nThe unreachable analyzer finds statements that execution can never reach\nbecause they are preceded by a return statement, a call to panic, an\ninfinite loop, or similar constructs.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unsafefuncs\"",
							"Doc": "replace unsafe pointer arithmetic with function calls\n\nThe unsafefuncs analyzer simplifies pointer arithmetic expressions by\nreplacing them with calls to helper functions such as unsafe.Add,\nadded in Go 1.17.\n\nExample:\n\n\tunsafe.Pointer(uintptr(ptr) + uintptr(n))\n\nwhere ptr is an unsafe.Pointer, is replaced by:\n\n\tunsafe.Add(ptr, n)",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unsafeptr\"",
							"Doc": "check for invalid conversions of uintptr to unsafe.Pointer\n\nThe unsafeptr analyzer reports likely incorrect uses of unsafe.Pointer\nto convert integers to pointers. A conversion from uintptr to\nunsafe.Pointer is invalid if it implies that there is a uintptr-typed\nword in memory that holds a pointer value, because that word will be\ninvisible to stack copying and to the garbage collector.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unusedfunc\"",
							"Doc": "check for unused functions, methods, etc\n\nThe unusedfunc analyzer reports functions and methods that are\nnever referenced outside of their own declaration.\n\nA function is considered unused if it is unexported and not\nreferenced (except within its own declaration).\n\nA method is considered unused if it is unexported, not referenced\n(except within its own declaration), and its name does not match\nthat of any method of an interface type declared within the same\npackage.\n\nThe tool may report false positives in some situations, for\nexample:\n\n  - for a declaration of an unexported function that is referenced\n    from another package using the go:linkname mechanism, if the\n    declaration's doc comment does not also have a go:linkname\n    comment.\n\n    (Such code is in any case strongly discouraged: linkname\n    annotations, if they must be used at all, should be used on both\n    the declaration and the alias.)\n\n  - for compiler intrinsics in the \"runtime\" package that, though\n    never referenced, are known to the compiler and are called\n    indirectly by compiled object code.\n\n  - for functions called only from assembly.\n\n  - for functions called only from files whose build tags are not\n    selected in the current build configuration.\n\nSince these situations are relatively common in the low-level parts\nof the runtime, this analyzer ignores the standard library.\nSee https://go.dev/issue/71686 and https://go.dev/issue/74130 for\nfurther discussion of these limitations.\n\nThe unusedfunc algorithm is not as precise as the\ngolang.org/x/tools/cmd/deadcode tool, but it has the advantage that\nit runs within the modular analysis framework, enabling near\nreal-time feedback within gopls.\n\nThe unusedfunc analyzer also reports unused types, vars, and\nconstants. Enums--constants defined with iota--are ignored since\neven the unused values must remain present to preserve the logical\nordering.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unusedparams\"",
							"Doc": "check for unused parameters of functions\n\nThe unusedparams analyzer checks functions to see if there are\nany parameters that are not being used.\n\nTo ensure soundness, it ignores:\n  - \"address-taken\" functions, that is, functions that are used as\n    a value rather than being called directly; their signatures may\n    be required to conform to a func type.\n  - exported functions or methods, since they may be address-taken\n    in another package.\n  - unexported methods whose name matches an interface method\n    declared in the same package, since the method's signature\n    may be required to conform to the interface type.\n  - functions with empty bodies, or containing just a call to panic.\n  - parameters that are unnamed, or named \"_\", the blank identifier.\n\nThe analyzer suggests a fix of replacing the parameter name by \"_\",\nbut in such cases a deeper fix can be obtained by invoking the\n\"Refactor: remove unused parameter\" code action, which will\neliminate the parameter entirely, along with all corresponding\narguments at call sites, while taking care to preserve any side\neffects in the argument expressions; see\nhttps://github.com/golang/tools/releases/tag/gopls%2Fv0.14.\n\nThis analyzer ignores generated code.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unusedresult\"",
							"Doc": "check for unused results of calls to some functions\n\nSome functions like fmt.Errorf return a result and have no side\neffects, so it is always a mistake to discard the result. Other\nfunctions may return an error that must not be ignored, or a cleanup\noperation that must be called. This analyzer reports calls to\nfunctions like these when the result of the call is ignored.\n\nThe set of functions may be controlled using flags.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unusedvariable\"",
							"Doc": "check for unused variables and suggest fixes",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"unusedwrite\"",
							"Doc": "checks for unused writes\n\nThe analyzer reports instances of writes to struct fields and\narrays that are never read. Specifically, when a struct object\nor an array is copied, its elements are copied implicitly by\nthe compiler, and any element write to this copy does nothing\nwith the original object.\n\nFor example:\n\n\ttype T struct { x int }\n\n\tfunc f(input []T) {\n\t\tfor i, v := range input {  // v is a copy\n\t\t\tv.x = i  // unused write to field x\n\t\t}\n\t}\n\nAnother example is about non-pointer receiver:\n\n\ttype T struct { x int }\n\n\tfunc (t T) f() {  // t is a copy\n\t\tt.x = i  // unused write to field x\n\t}",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"waitgroup\"",
							"Doc": "check for misuses of sync.WaitGroup\n\nThis analyzer detects mistaken calls to the (*sync.WaitGroup).Add\nmethod from inside a new goroutine, causing Add to race with Wait:\n\n\t// WRONG\n\tvar wg sync.WaitGroup\n\tgo func() {\n\t        wg.Add(1) // \"WaitGroup.Add called from inside new goroutine\"\n\t        defer wg.Done()\n\t        ...\n\t}()\n\twg.Wait() // (may return prematurely before new goroutine starts)\n\nThe correct code calls Add before starting the goroutine:\n\n\t// RIGHT\n\tvar wg sync.WaitGroup\n\twg.Add(1)\n\tgo func() {\n\t\tdefer wg.Done()\n\t\t...\n\t}()\n\twg.Wait()",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"waitgroupgo\"",
							"Doc": "replace wg.Add(1)/go/wg.Done() with wg.Go\n\nThe waitgroupgo analyzer simplifies goroutine management with `sync.WaitGroup`.\nIt replaces the common pattern\n\n\twg.Add(1)\n\tgo func() {\n\t\tdefer wg.Done()\n\t\t...\n\t}()\n\nwith a single call to\n\n\twg.Go(func(){ ... })\n\nwhich was added in Go 1.25.",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"writestring\"",
							"Doc": "detect inefficient string concatenation in uses of WriteString\n\nThe writestring analyzer offers to replace a call to WriteString(x + y) by\ntwo calls WriteString(x); WriteString(y). This is more efficient because it\navoids the additional memory allocation produced by string concatenation;\ninstead we just write each string into the buffer directly.\n\nIt explicitly looks for calls to certain well-known writers such as\nbytes.Buffer, strings.Builder and bufio.Writer. The analyzer will not suggest\na fix for calls to, say, (*os.File).WriteString, because for certain kinds of\nfile such as a UDP socket, it could split a single message into two.\nSimilarly it does not offer fixes when the type of the writer is unknown (as\nin calls to io.WriteString).\n\nFor example:\n\n\tfunc f(a string, b string) string {\n\t\t var s strings.Builder\n\t\t s.WriteString(a+b)\n\t\t return s.String()\n\t}\n\nwould become:\n\n\tfunc f(a string, b string) string {\n\t\tvar s strings.Builder\n\t\ts.WriteString(a)\n\t\ts.WriteString(b)\n\t\treturn s.String()\n\t}",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"yield\"",
							"Doc": "report calls to yield where the result is ignored\n\nAfter a yield function returns false, the caller should not call\nthe yield function again; generally the iterator should return\npromptly.\n\nThis example fails to check the result of the call to yield,\ncausing this analyzer to report a diagnostic:\n\n\tyield(1) // yield may be called again (on L2) after returning false\n\tyield(2)\n\nThe corrected code is either this:\n\n\tif yield(1) { yield(2) }\n\nor simply:\n\n\t_ = yield(1) \u0026\u0026 yield(2)\n\nIt is not always a mistake to ignore the result of yield.\nFor example, this is a valid single-element iterator:\n\n\tyield(1) // ok to ignore result\n\treturn\n\nIt is only a mistake when the yield call that returned false may be\nfollowed by another call.",
							"Default": "true",
							"Status": ""
						}
					]
				},
				"EnumValues": null,
				"Default": "{}",
				"Status": "",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "staticcheck",
				"Type": "bool",
				"Doc": "staticcheck configures the default set of analyses staticcheck.io.\nThese analyses are documented on\n[Staticcheck's website](https://staticcheck.io/docs/checks/).\n\nThe \"staticcheck\" option has three values:\n- false: disable all staticcheck analyzers\n- true: enable all staticcheck analyzers\n- unset: enable a subset of staticcheck analyzers\n  selected by gopls maintainers for runtime efficiency\n  and analytic precision.\n\nRegardless of this setting, individual analyzers can be\nselectively enabled or disabled using the `analyses` setting.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "staticcheckProvided",
				"Type": "bool",
				"Doc": "",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "annotations",
				"Type": "map[enum]bool",
				"Doc": "annotations specifies the various kinds of compiler\noptimization details that should be reported as diagnostics\nwhen enabled for a package by the \"Toggle compiler\noptimization details\" (`gopls.gc_details`) command.\n\n(Some users care only about one kind of annotation in their\nprofiling efforts. More importantly, in large packages, the\nnumber of annotations can sometimes overwhelm the user\ninterface and exceed the per-file diagnostic limit.)\n\nTODO(adonovan): rename this field to CompilerOptDetail.\n",
				"EnumKeys": {
					"ValueType": "bool",
					"Keys": [
						{
							"Name": "\"bounds\"",
							"Doc": "`\"bounds\"` controls bounds checking diagnostics.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"escape\"",
							"Doc": "`\"escape\"` controls diagnostics about escape choices.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"inline\"",
							"Doc": "`\"inline\"` controls diagnostics about inlining choices.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"nil\"",
							"Doc": "`\"nil\"` controls nil checks.\n",
							"Default": "true",
							"Status": ""
						}
					]
				},
				"EnumValues": null,
				"Default": "{\"bounds\":true,\"escape\":true,\"inline\":true,\"nil\":true}",
				"Status": "",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "vulncheck",
				"Type": "enum",
				"Doc": "vulncheck enables vulnerability scanning.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"Imports\"",
						"Doc": "`\"Imports\"`: In Imports mode, `gopls` will report vulnerabilities that affect packages\ndirectly and indirectly used by the analyzed main module.\n",
						"Status": ""
					},
					{
						"Value": "\"Off\"",
						"Doc": "`\"Off\"`: Disable vulnerability analysis.\n",
						"Status": ""
					},
					{
						"Value": "\"Prompt\"",
						"Doc": "`\"Prompt\"`: Vulncheck can be triggered via prompt.\n",
						"Status": ""
					}
				],
				"Default": "\"Prompt\"",
				"Status": "experimental",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "diagnosticsDelay",
				"Type": "time.Duration",
				"Doc": "diagnosticsDelay controls the amount of time that gopls waits\nafter the most recent file modification before computing deep diagnostics.\nSimple diagnostics (parsing and type-checking) are always run immediately\non recently modified packages.\n\nThis option must be set to a valid duration string, for example `\"250ms\"`.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "\"1s\"",
				"Status": "advanced",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "diagnosticsTrigger",
				"Type": "enum",
				"Doc": "diagnosticsTrigger controls when to run diagnostics.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": [
					{
						"Value": "\"Edit\"",
						"Doc": "`\"Edit\"`: Trigger diagnostics on file edit and save. (default)\n",
						"Status": ""
					},
					{
						"Value": "\"Save\"",
						"Doc": "`\"Save\"`: Trigger diagnostics only on file save. Events like initial workspace load\nor configuration change will still trigger diagnostics.\n",
						"Status": ""
					}
				],
				"Default": "\"Edit\"",
				"Status": "experimental",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "analysisProgressReporting",
				"Type": "bool",
				"Doc": "analysisProgressReporting controls whether gopls sends progress\nnotifications when construction of its index of analysis facts is taking a\nlong time. Cancelling these notifications will cancel the indexing task,\nthough it will restart after the next change in the workspace.\n\nWhen a package is opened for the first time and heavyweight analyses such as\nstaticcheck are enabled, it can take a while to construct the index of\nanalysis facts for all its dependencies. The index is cached in the\nfilesystem, so subsequent analysis should be faster.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "true",
				"Status": "",
				"Hierarchy": "ui.diagnostic",
				"DeprecationMessage": ""
			},
			{
				"Name": "hints",
				"Type": "map[enum]bool",
				"Doc": "hints specify inlay hints that users want to see. A full list of hints\nthat gopls uses can be found in\n[inlayHints.md](https://github.com/golang/tools/blob/master/gopls/doc/inlayHints.md).\n",
				"EnumKeys": {
					"ValueType": "bool",
					"Keys": [
						{
							"Name": "\"assignVariableTypes\"",
							"Doc": "`\"assignVariableTypes\"` controls inlay hints for variable types in assign statements:\n```go\n\ti/* int*/, j/* int*/ := 0, len(r)-1\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"compositeLiteralFields\"",
							"Doc": "`\"compositeLiteralFields\"` inlay hints for composite literal field names:\n```go\n\t{/*in: */\"Hello, world\", /*want: */\"dlrow ,olleH\"}\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"compositeLiteralTypes\"",
							"Doc": "`\"compositeLiteralTypes\"` controls inlay hints for composite literal types:\n```go\n\tfor _, c := range []struct {\n\t\tin, want string\n\t}{\n\t\t/*struct{ in string; want string }*/{\"Hello, world\", \"dlrow ,olleH\"},\n\t}\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"constantValues\"",
							"Doc": "`\"constantValues\"` controls inlay hints for constant values:\n```go\n\tconst (\n\t\tKindNone   Kind = iota/* = 0*/\n\t\tKindPrint/*  = 1*/\n\t\tKindPrintf/* = 2*/\n\t\tKindErrorf/* = 3*/\n\t)\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"functionTypeParameters\"",
							"Doc": "`\"functionTypeParameters\"` inlay hints for implicit type parameters on generic functions:\n```go\n\tmyFoo/*[int, string]*/(1, \"hello\")\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"ignoredError\"",
							"Doc": "`\"ignoredError\"` inlay hints for implicitly discarded errors:\n```go\n\tf.Close() // ignore error\n```\nThis check inserts an `// ignore error` hint following any\nstatement that is a function call whose error result is\nimplicitly ignored.\n\nTo suppress the hint, write an actual comment containing\n\"ignore error\" following the call statement, or explicitly\nassign the result to a blank variable. A handful of common\nfunctions such as `fmt.Println` are excluded from the\ncheck.\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"parameterNames\"",
							"Doc": "`\"parameterNames\"` controls inlay hints for parameter names:\n```go\n\tparseInt(/* str: */ \"123\", /* radix: */ 8)\n```\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"rangeVariableTypes\"",
							"Doc": "`\"rangeVariableTypes\"` controls inlay hints for variable types in range statements:\n```go\n\tfor k/* int*/, v/* string*/ := range []string{} {\n\t\tfmt.Println(k, v)\n\t}\n```\n",
							"Default": "false",
							"Status": ""
						}
					]
				},
				"EnumValues": null,
				"Default": "{}",
				"Status": "experimental",
				"Hierarchy": "ui.inlayhint",
				"DeprecationMessage": ""
			},
			{
				"Name": "codelenses",
				"Type": "map[enum]bool",
				"Doc": "codelenses overrides the enabled/disabled state of each of gopls'\nsources of [Code Lenses](codelenses.md).\n\nExample Usage:\n\n```json5\n\"gopls\": {\n...\n  \"codelenses\": {\n    \"generate\": false,  // Don't show the `go generate` lens.\n  }\n...\n}\n```\n",
				"EnumKeys": {
					"ValueType": "bool",
					"Keys": [
						{
							"Name": "\"generate\"",
							"Doc": "`\"generate\"`: Run `go generate`\n\nThis codelens source annotates any `//go:generate` comments\nwith commands to run `go generate` in this directory, on\nall directories recursively beneath this one.\n\nSee [Generating code](https://go.dev/blog/generate) for\nmore details.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"regenerate_cgo\"",
							"Doc": "`\"regenerate_cgo\"`: Re-generate cgo declarations\n\nThis codelens source annotates an `import \"C\"` declaration\nwith a command to re-run the [cgo\ncommand](https://pkg.go.dev/cmd/cgo) to regenerate the\ncorresponding Go declarations.\n\nUse this after editing the C code in comments attached to\nthe import, or in C header files included by it.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"run_govulncheck\"",
							"Doc": "`\"run_govulncheck\"`: Run govulncheck (legacy)\n\nThis codelens source annotates the `module` directive in a go.mod file\nwith a command to run Govulncheck asynchronously.\n\n[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that\ncomputes the set of functions reachable within your application, including\ndependencies; queries a database of known security vulnerabilities; and\nreports any potential problems it finds.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"test\"",
							"Doc": "`\"test\"`: Run tests and benchmarks\n\nThis codelens source annotates each `Test` and `Benchmark`\nfunction in a `*_test.go` file with a command to run it.\n\nThis source is off by default because VS Code has\na client-side custom UI for testing, and because progress\nnotifications are not a great UX for streamed test output.\nSee:\n- golang/go#67400 for a discussion of this feature.\n- https://github.com/joaotavora/eglot/discussions/1402\n  for an alternative approach.\n",
							"Default": "false",
							"Status": ""
						},
						{
							"Name": "\"tidy\"",
							"Doc": "`\"tidy\"`: Tidy go.mod file\n\nThis codelens source annotates the `module` directive in a\ngo.mod file with a command to run [`go mod\ntidy`](https://go.dev/ref/mod#go-mod-tidy), which ensures\nthat the go.mod file matches the source code in the module.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"upgrade_dependency\"",
							"Doc": "`\"upgrade_dependency\"`: Update dependencies\n\nThis codelens source annotates the `module` directive in a\ngo.mod file with commands to:\n\n- check for available upgrades,\n- upgrade direct dependencies, and\n- upgrade all dependencies transitively.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"vendor\"",
							"Doc": "`\"vendor\"`: Update vendor directory\n\nThis codelens source annotates the `module` directive in a\ngo.mod file with a command to run [`go mod\nvendor`](https://go.dev/ref/mod#go-mod-vendor), which\ncreates or updates the directory named `vendor` in the\nmodule root so that it contains an up-to-date copy of all\nnecessary package dependencies.\n",
							"Default": "true",
							"Status": ""
						},
						{
							"Name": "\"vulncheck\"",
							"Doc": "`\"vulncheck\"`: Run govulncheck\n\nThis codelens source annotates the `module` directive in a go.mod file\nwith a command to run govulncheck synchronously.\n\n[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that\ncomputes the set of functions reachable within your application, including\ndependencies; queries a database of known security vulnerabilities; and\nreports any potential problems it finds.\n",
							"Default": "false",
							"Status": "experimental"
						}
					]
				},
				"EnumValues": null,
				"Default": "{\"generate\":true,\"regenerate_cgo\":true,\"run_govulncheck\":true,\"tidy\":true,\"upgrade_dependency\":true,\"vendor\":true}",
				"Status": "",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "semanticTokens",
				"Type": "bool",
				"Doc": "semanticTokens determines whether gopls will return a\nSemanticTokensProvider at initialization, or respond\nto request for semantic tokens.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "noSemanticString",
				"Type": "bool",
				"Doc": "noSemanticString turns off the sending of the semantic token 'string'\n\nDeprecated: Use SemanticTokenTypes[\"string\"] = false instead. See\ngolang/vscode-go#3632\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": "use SemanticTokenTypes[\"string\"] = false instead. See\ngolang/vscode-go#3632\n"
			},
			{
				"Name": "noSemanticNumber",
				"Type": "bool",
				"Doc": "noSemanticNumber turns off the sending of the semantic token 'number'\n\nDeprecated: Use SemanticTokenTypes[\"number\"] = false instead. See\ngolang/vscode-go#3632.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": "use SemanticTokenTypes[\"number\"] = false instead. See\ngolang/vscode-go#3632.\n"
			},
			{
				"Name": "semanticTokenTypes",
				"Type": "map[string]bool",
				"Doc": "semanticTokenTypes configures the semantic token types. It allows\ndisabling types by setting each value to false.\nBy default, all types are enabled.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "{}",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "semanticTokenModifiers",
				"Type": "map[string]bool",
				"Doc": "semanticTokenModifiers configures the semantic token modifiers. It allows\ndisabling modifiers by setting each value to false.\nBy default, all modifiers are enabled.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "{}",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "newGoFileHeader",
				"Type": "bool",
				"Doc": "newGoFileHeader enables automatic insertion of the copyright comment\nand package declaration in a newly created Go file.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "true",
				"Status": "",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "renameMovesSubpackages",
				"Type": "bool",
				"Doc": "renameMovesSubpackages enables Rename operations on packages to\nmove subdirectories of the target package.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "experimental",
				"Hierarchy": "ui",
				"DeprecationMessage": ""
			},
			{
				"Name": "local",
				"Type": "string",
				"Doc": "local is the equivalent of the `goimports -local` flag, which puts\nimports beginning with this string after third-party packages. It should\nbe the prefix of the import path whose imports should be grouped\nseparately.\n\nIt is used when tidying imports (during an LSP Organize\nImports request) or when inserting new ones (for example,\nduring completion); an LSP Formatting request merely sorts the\nexisting imports.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "\"\"",
				"Status": "",
				"Hierarchy": "formatting",
				"DeprecationMessage": ""
			},
			{
				"Name": "gofumpt",
				"Type": "bool",
				"Doc": "gofumpt indicates if we should run gofumpt formatting.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "",
				"Hierarchy": "formatting",
				"DeprecationMessage": ""
			},
			{
				"Name": "maxFileCacheBytes",
				"Type": "int64",
				"Doc": "maxFileCacheBytes sets a soft limit on the file cache size in bytes.\nIf zero, the default budget is used.\n\nThe cache may temporarily use more than this amount.\nAlso, this parameter limits file contents; disk block usage\nas measured by du(1) may be significantly higher.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "0",
				"Status": "experimental",
				"Hierarchy": "",
				"DeprecationMessage": ""
			},
			{
				"Name": "verboseOutput",
				"Type": "bool",
				"Doc": "verboseOutput enables additional debug logging.\n",
				"EnumKeys": {
					"ValueType": "",
					"Keys": null
				},
				"EnumValues": null,
				"Default": "false",
				"Status": "debug",
				"Hierarchy": "",
				"DeprecationMessage": ""
			}
		]
	},
	"Lenses": [
		{
			"FileType": "Go",
			"Lens": "generate",
			"Title": "Run `go generate`",
			"Doc": "\nThis codelens source annotates any `//go:generate` comments\nwith commands to run `go generate` in this directory, on\nall directories recursively beneath this one.\n\nSee [Generating code](https://go.dev/blog/generate) for\nmore details.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "Go",
			"Lens": "regenerate_cgo",
			"Title": "Re-generate cgo declarations",
			"Doc": "\nThis codelens source annotates an `import \"C\"` declaration\nwith a command to re-run the [cgo\ncommand](https://pkg.go.dev/cmd/cgo) to regenerate the\ncorresponding Go declarations.\n\nUse this after editing the C code in comments attached to\nthe import, or in C header files included by it.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "Go",
			"Lens": "test",
			"Title": "Run tests and benchmarks",
			"Doc": "\nThis codelens source annotates each `Test` and `Benchmark`\nfunction in a `*_test.go` file with a command to run it.\n\nThis source is off by default because VS Code has\na client-side custom UI for testing, and because progress\nnotifications are not a great UX for streamed test output.\nSee:\n- golang/go#67400 for a discussion of this feature.\n- https://github.com/joaotavora/eglot/discussions/1402\n  for an alternative approach.\n",
			"Default": false,
			"Status": ""
		},
		{
			"FileType": "go.mod",
			"Lens": "run_govulncheck",
			"Title": "Run govulncheck (legacy)",
			"Doc": "\nThis codelens source annotates the `module` directive in a go.mod file\nwith a command to run Govulncheck asynchronously.\n\n[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that\ncomputes the set of functions reachable within your application, including\ndependencies; queries a database of known security vulnerabilities; and\nreports any potential problems it finds.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "go.mod",
			"Lens": "tidy",
			"Title": "Tidy go.mod file",
			"Doc": "\nThis codelens source annotates the `module` directive in a\ngo.mod file with a command to run [`go mod\ntidy`](https://go.dev/ref/mod#go-mod-tidy), which ensures\nthat the go.mod file matches the source code in the module.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "go.mod",
			"Lens": "upgrade_dependency",
			"Title": "Update dependencies",
			"Doc": "\nThis codelens source annotates the `module` directive in a\ngo.mod file with commands to:\n\n- check for available upgrades,\n- upgrade direct dependencies, and\n- upgrade all dependencies transitively.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "go.mod",
			"Lens": "vendor",
			"Title": "Update vendor directory",
			"Doc": "\nThis codelens source annotates the `module` directive in a\ngo.mod file with a command to run [`go mod\nvendor`](https://go.dev/ref/mod#go-mod-vendor), which\ncreates or updates the directory named `vendor` in the\nmodule root so that it contains an up-to-date copy of all\nnecessary package dependencies.\n",
			"Default": true,
			"Status": ""
		},
		{
			"FileType": "go.mod",
			"Lens": "vulncheck",
			"Title": "Run govulncheck",
			"Doc": "\nThis codelens source annotates the `module` directive in a go.mod file\nwith a command to run govulncheck synchronously.\n\n[Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that\ncomputes the set of functions reachable within your application, including\ndependencies; queries a database of known security vulnerabilities; and\nreports any potential problems it finds.\n",
			"Default": false,
			"Status": "experimental"
		}
	],
	"Analyzers": [
		{
			"Name": "QF1001",
			"Doc": "Apply De Morgan's law\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1001",
			"Default": false
		},
		{
			"Name": "QF1002",
			"Doc": "Convert untagged switch to tagged switch\n\nAn untagged switch that compares a single variable against a series of\nvalues can be replaced with a tagged switch.\n\nBefore:\n\n    switch {\n    case x == 1 || x == 2, x == 3:\n        ...\n    case x == 4:\n        ...\n    default:\n        ...\n    }\n\nAfter:\n\n    switch x {\n    case 1, 2, 3:\n        ...\n    case 4:\n        ...\n    default:\n        ...\n    }\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1002",
			"Default": true
		},
		{
			"Name": "QF1003",
			"Doc": "Convert if/else-if chain to tagged switch\n\nA series of if/else-if checks comparing the same variable against\nvalues can be replaced with a tagged switch.\n\nBefore:\n\n    if x == 1 || x == 2 {\n        ...\n    } else if x == 3 {\n        ...\n    } else {\n        ...\n    }\n\nAfter:\n\n    switch x {\n    case 1, 2:\n        ...\n    case 3:\n        ...\n    default:\n        ...\n    }\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1003",
			"Default": true
		},
		{
			"Name": "QF1004",
			"Doc": "Use strings.ReplaceAll instead of strings.Replace with n == -1\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1004",
			"Default": true
		},
		{
			"Name": "QF1005",
			"Doc": "Expand call to math.Pow\n\nSome uses of math.Pow can be simplified to basic multiplication.\n\nBefore:\n\n    math.Pow(x, 2)\n\nAfter:\n\n    x * x\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1005",
			"Default": false
		},
		{
			"Name": "QF1006",
			"Doc": "Lift if+break into loop condition\n\nBefore:\n\n    for {\n        if done {\n            break\n        }\n        ...\n    }\n\nAfter:\n\n    for !done {\n        ...\n    }\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1006",
			"Default": false
		},
		{
			"Name": "QF1007",
			"Doc": "Merge conditional assignment into variable declaration\n\nBefore:\n\n    x := false\n    if someCondition {\n        x = true\n    }\n\nAfter:\n\n    x := someCondition\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1007",
			"Default": false
		},
		{
			"Name": "QF1008",
			"Doc": "Omit embedded fields from selector expression\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1008",
			"Default": false
		},
		{
			"Name": "QF1009",
			"Doc": "Use time.Time.Equal instead of == operator\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1009",
			"Default": true
		},
		{
			"Name": "QF1010",
			"Doc": "Convert slice of bytes to string when printing it\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1010",
			"Default": true
		},
		{
			"Name": "QF1011",
			"Doc": "Omit redundant type from variable declaration\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#",
			"Default": false
		},
		{
			"Name": "QF1012",
			"Doc": "Use fmt.Fprintf(x, ...) instead of x.Write(fmt.Sprintf(...))\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#QF1012",
			"Default": true
		},
		{
			"Name": "S1000",
			"Doc": "Use plain channel send or receive instead of single-case select\n\nSelect statements with a single case can be replaced with a simple\nsend or receive.\n\nBefore:\n\n    select {\n    case x := \u003c-ch:\n        fmt.Println(x)\n    }\n\nAfter:\n\n    x := \u003c-ch\n    fmt.Println(x)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1000",
			"Default": true
		},
		{
			"Name": "S1001",
			"Doc": "Replace for loop with call to copy\n\nUse copy() for copying elements from one slice to another. For\narrays of identical size, you can use simple assignment.\n\nBefore:\n\n    for i, x := range src {\n        dst[i] = x\n    }\n\nAfter:\n\n    copy(dst, src)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1001",
			"Default": true
		},
		{
			"Name": "S1002",
			"Doc": "Omit comparison with boolean constant\n\nBefore:\n\n    if x == true {}\n\nAfter:\n\n    if x {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1002",
			"Default": false
		},
		{
			"Name": "S1003",
			"Doc": "Replace call to strings.Index with strings.Contains\n\nBefore:\n\n    if strings.Index(x, y) != -1 {}\n\nAfter:\n\n    if strings.Contains(x, y) {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1003",
			"Default": true
		},
		{
			"Name": "S1004",
			"Doc": "Replace call to bytes.Compare with bytes.Equal\n\nBefore:\n\n    if bytes.Compare(x, y) == 0 {}\n\nAfter:\n\n    if bytes.Equal(x, y) {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1004",
			"Default": true
		},
		{
			"Name": "S1005",
			"Doc": "Drop unnecessary use of the blank identifier\n\nIn many cases, assigning to the blank identifier is unnecessary.\n\nBefore:\n\n    for _ = range s {}\n    x, _ = someMap[key]\n    _ = \u003c-ch\n\nAfter:\n\n    for range s{}\n    x = someMap[key]\n    \u003c-ch\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1005",
			"Default": false
		},
		{
			"Name": "S1006",
			"Doc": "Use 'for { ... }' for infinite loops\n\nFor infinite loops, using for { ... } is the most idiomatic choice.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1006",
			"Default": false
		},
		{
			"Name": "S1007",
			"Doc": "Simplify regular expression by using raw string literal\n\nRaw string literals use backticks instead of quotation marks and do not support\nany escape sequences. This means that the backslash can be used\nfreely, without the need of escaping.\n\nSince regular expressions have their own escape sequences, raw strings\ncan improve their readability.\n\nBefore:\n\n    regexp.Compile(\"\\\\A(\\\\w+) profile: total \\\\d+\\\\n\\\\z\")\n\nAfter:\n\n    regexp.Compile(`\\A(\\w+) profile: total \\d+\\n\\z`)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1007",
			"Default": true
		},
		{
			"Name": "S1008",
			"Doc": "Simplify returning boolean expression\n\nBefore:\n\n    if \u003cexpr\u003e {\n        return true\n    }\n    return false\n\nAfter:\n\n    return \u003cexpr\u003e\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1008",
			"Default": false
		},
		{
			"Name": "S1009",
			"Doc": "Omit redundant nil check on slices, maps, and channels\n\nThe len function is defined for all slices, maps, and\nchannels, even nil ones, which have a length of zero. It is not necessary to\ncheck for nil before checking that their length is not zero.\n\nBefore:\n\n    if x != nil \u0026\u0026 len(x) != 0 {}\n\nAfter:\n\n    if len(x) != 0 {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1009",
			"Default": true
		},
		{
			"Name": "S1010",
			"Doc": "Omit default slice index\n\nWhen slicing, the second index defaults to the length of the value,\nmaking s[n:len(s)] and s[n:] equivalent.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1010",
			"Default": true
		},
		{
			"Name": "S1011",
			"Doc": "Use a single append to concatenate two slices\n\nBefore:\n\n    for _, e := range y {\n        x = append(x, e)\n    }\n    \n    for i := range y {\n        x = append(x, y[i])\n    }\n    \n    for i := range y {\n        v := y[i]\n        x = append(x, v)\n    }\n\nAfter:\n\n    x = append(x, y...)\n    x = append(x, y...)\n    x = append(x, y...)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1011",
			"Default": false
		},
		{
			"Name": "S1012",
			"Doc": "Replace time.Now().Sub(x) with time.Since(x)\n\nThe time.Since helper has the same effect as using time.Now().Sub(x)\nbut is easier to read.\n\nBefore:\n\n    time.Now().Sub(x)\n\nAfter:\n\n    time.Since(x)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1012",
			"Default": true
		},
		{
			"Name": "S1016",
			"Doc": "Use a type conversion instead of manually copying struct fields\n\nTwo struct types with identical fields can be converted between each\nother. In older versions of Go, the fields had to have identical\nstruct tags. Since Go 1.8, however, struct tags are ignored during\nconversions. It is thus not necessary to manually copy every field\nindividually.\n\nBefore:\n\n    var x T1\n    y := T2{\n        Field1: x.Field1,\n        Field2: x.Field2,\n    }\n\nAfter:\n\n    var x T1\n    y := T2(x)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1016",
			"Default": false
		},
		{
			"Name": "S1017",
			"Doc": "Replace manual trimming with strings.TrimPrefix\n\nInstead of using strings.HasPrefix and manual slicing, use the\nstrings.TrimPrefix function. If the string doesn't start with the\nprefix, the original string will be returned. Using strings.TrimPrefix\nreduces complexity, and avoids common bugs, such as off-by-one\nmistakes.\n\nBefore:\n\n    if strings.HasPrefix(str, prefix) {\n        str = str[len(prefix):]\n    }\n\nAfter:\n\n    str = strings.TrimPrefix(str, prefix)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1017",
			"Default": true
		},
		{
			"Name": "S1018",
			"Doc": "Use 'copy' for sliding elements\n\ncopy() permits using the same source and destination slice, even with\noverlapping ranges. This makes it ideal for sliding elements in a\nslice.\n\nBefore:\n\n    for i := 0; i \u003c n; i++ {\n        bs[i] = bs[offset+i]\n    }\n\nAfter:\n\n    copy(bs[:n], bs[offset:])\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1018",
			"Default": true
		},
		{
			"Name": "S1019",
			"Doc": "Simplify 'make' call by omitting redundant arguments\n\nThe 'make' function has default values for the length and capacity\narguments. For channels, the length defaults to zero, and for slices,\nthe capacity defaults to the length.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1019",
			"Default": true
		},
		{
			"Name": "S1020",
			"Doc": "Omit redundant nil check in type assertion\n\nBefore:\n\n    if _, ok := i.(T); ok \u0026\u0026 i != nil {}\n\nAfter:\n\n    if _, ok := i.(T); ok {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1020",
			"Default": true
		},
		{
			"Name": "S1021",
			"Doc": "Merge variable declaration and assignment\n\nBefore:\n\n    var x uint\n    x = 1\n\nAfter:\n\n    var x uint = 1\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1021",
			"Default": false
		},
		{
			"Name": "S1023",
			"Doc": "Omit redundant control flow\n\nFunctions that have no return value do not need a return statement as\nthe final statement of the function.\n\nSwitches in Go do not have automatic fallthrough, unlike languages\nlike C. It is not necessary to have a break statement as the final\nstatement in a case block.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1023",
			"Default": true
		},
		{
			"Name": "S1024",
			"Doc": "Replace x.Sub(time.Now()) with time.Until(x)\n\nThe time.Until helper has the same effect as using x.Sub(time.Now())\nbut is easier to read.\n\nBefore:\n\n    x.Sub(time.Now())\n\nAfter:\n\n    time.Until(x)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1024",
			"Default": true
		},
		{
			"Name": "S1025",
			"Doc": "Don't use fmt.Sprintf(\"%s\", x) unnecessarily\n\nIn many instances, there are easier and more efficient ways of getting\na value's string representation. Whenever a value's underlying type is\na string already, or the type has a String method, they should be used\ndirectly.\n\nGiven the following shared definitions\n\n    type T1 string\n    type T2 int\n\n    func (T2) String() string { return \"Hello, world\" }\n\n    var x string\n    var y T1\n    var z T2\n\nwe can simplify\n\n    fmt.Sprintf(\"%s\", x)\n    fmt.Sprintf(\"%s\", y)\n    fmt.Sprintf(\"%s\", z)\n\nto\n\n    x\n    string(y)\n    z.String()\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1025",
			"Default": false
		},
		{
			"Name": "S1028",
			"Doc": "Simplify error construction with fmt.Errorf\n\nBefore:\n\n    errors.New(fmt.Sprintf(...))\n\nAfter:\n\n    fmt.Errorf(...)\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1028",
			"Default": true
		},
		{
			"Name": "S1029",
			"Doc": "Range over the string directly\n\nRanging over a string will yield byte offsets and runes. If the offset\nisn't used, this is functionally equivalent to converting the string\nto a slice of runes and ranging over that. Ranging directly over the\nstring will be more performant, however, as it avoids allocating a new\nslice, the size of which depends on the length of the string.\n\nBefore:\n\n    for _, r := range []rune(s) {}\n\nAfter:\n\n    for _, r := range s {}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1029",
			"Default": false
		},
		{
			"Name": "S1030",
			"Doc": "Use bytes.Buffer.String or bytes.Buffer.Bytes\n\nbytes.Buffer has both a String and a Bytes method. It is almost never\nnecessary to use string(buf.Bytes()) or []byte(buf.String()) – simply\nuse the other method.\n\nThe only exception to this are map lookups. Due to a compiler optimization,\nm[string(buf.Bytes())] is more efficient than m[buf.String()].\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1030",
			"Default": true
		},
		{
			"Name": "S1031",
			"Doc": "Omit redundant nil check around loop\n\nYou can use range on nil slices and maps, the loop will simply never\nexecute. This makes an additional nil check around the loop\nunnecessary.\n\nBefore:\n\n    if s != nil {\n        for _, x := range s {\n            ...\n        }\n    }\n\nAfter:\n\n    for _, x := range s {\n        ...\n    }\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1031",
			"Default": true
		},
		{
			"Name": "S1032",
			"Doc": "Use sort.Ints(x), sort.Float64s(x), and sort.Strings(x)\n\nThe sort.Ints, sort.Float64s and sort.Strings functions are easier to\nread than sort.Sort(sort.IntSlice(x)), sort.Sort(sort.Float64Slice(x))\nand sort.Sort(sort.StringSlice(x)).\n\nBefore:\n\n    sort.Sort(sort.StringSlice(x))\n\nAfter:\n\n    sort.Strings(x)\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1032",
			"Default": true
		},
		{
			"Name": "S1033",
			"Doc": "Unnecessary guard around call to 'delete'\n\nCalling delete on a nil map is a no-op.\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1033",
			"Default": true
		},
		{
			"Name": "S1034",
			"Doc": "Use result of type assertion to simplify cases\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1034",
			"Default": true
		},
		{
			"Name": "S1035",
			"Doc": "Redundant call to net/http.CanonicalHeaderKey in method call on net/http.Header\n\nThe methods on net/http.Header, namely Add, Del, Get\nand Set, already canonicalize the given header name.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1035",
			"Default": true
		},
		{
			"Name": "S1036",
			"Doc": "Unnecessary guard around map access\n\nWhen accessing a map key that doesn't exist yet, one receives a zero\nvalue. Often, the zero value is a suitable value, for example when\nusing append or doing integer math.\n\nThe following\n\n    if _, ok := m[\"foo\"]; ok {\n        m[\"foo\"] = append(m[\"foo\"], \"bar\")\n    } else {\n        m[\"foo\"] = []string{\"bar\"}\n    }\n\ncan be simplified to\n\n    m[\"foo\"] = append(m[\"foo\"], \"bar\")\n\nand\n\n    if _, ok := m2[\"k\"]; ok {\n        m2[\"k\"] += 4\n    } else {\n        m2[\"k\"] = 4\n    }\n\ncan be simplified to\n\n    m[\"k\"] += 4\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1036",
			"Default": true
		},
		{
			"Name": "S1037",
			"Doc": "Elaborate way of sleeping\n\nUsing a select statement with a single case receiving\nfrom the result of time.After is a very elaborate way of sleeping that\ncan much simpler be expressed with a simple call to time.Sleep.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1037",
			"Default": true
		},
		{
			"Name": "S1038",
			"Doc": "Unnecessarily complex way of printing formatted string\n\nInstead of using fmt.Print(fmt.Sprintf(...)), one can use fmt.Printf(...).\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1038",
			"Default": true
		},
		{
			"Name": "S1039",
			"Doc": "Unnecessary use of fmt.Sprint\n\nCalling fmt.Sprint with a single string argument is unnecessary\nand identical to using the string directly.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1039",
			"Default": true
		},
		{
			"Name": "S1040",
			"Doc": "Type assertion to current type\n\nThe type assertion x.(SomeInterface), when x already has type\nSomeInterface, can only fail if x is nil. Usually, this is\nleft-over code from when x had a different type and you can safely\ndelete the type assertion. If you want to check that x is not nil,\nconsider being explicit and using an actual if x == nil comparison\ninstead of relying on the type assertion panicking.\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#S1040",
			"Default": true
		},
		{
			"Name": "SA1000",
			"Doc": "Invalid regular expression\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1000",
			"Default": false
		},
		{
			"Name": "SA1001",
			"Doc": "Invalid template\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1001",
			"Default": true
		},
		{
			"Name": "SA1002",
			"Doc": "Invalid format in time.Parse\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1002",
			"Default": false
		},
		{
			"Name": "SA1003",
			"Doc": "Unsupported argument to functions in encoding/binary\n\nThe encoding/binary package can only serialize types with known sizes.\nThis precludes the use of the int and uint types, as their sizes\ndiffer on different architectures. Furthermore, it doesn't support\nserializing maps, channels, strings, or functions.\n\nBefore Go 1.8, bool wasn't supported, either.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1003",
			"Default": false
		},
		{
			"Name": "SA1004",
			"Doc": "Suspiciously small untyped constant in time.Sleep\n\nThe time.Sleep function takes a time.Duration as its only argument.\nDurations are expressed in nanoseconds. Thus, calling time.Sleep(1)\nwill sleep for 1 nanosecond. This is a common source of bugs, as sleep\nfunctions in other languages often accept seconds or milliseconds.\n\nThe time package provides constants such as time.Second to express\nlarge durations. These can be combined with arithmetic to express\narbitrary durations, for example 5 * time.Second for 5 seconds.\n\nIf you truly meant to sleep for a tiny amount of time, use\nn * time.Nanosecond to signal to Staticcheck that you did mean to sleep\nfor some amount of nanoseconds.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1004",
			"Default": true
		},
		{
			"Name": "SA1005",
			"Doc": "Invalid first argument to exec.Command\n\nos/exec runs programs directly (using variants of the fork and exec\nsystem calls on Unix systems). This shouldn't be confused with running\na command in a shell. The shell will allow for features such as input\nredirection, pipes, and general scripting. The shell is also\nresponsible for splitting the user's input into a program name and its\narguments. For example, the equivalent to\n\n    ls / /tmp\n\nwould be\n\n    exec.Command(\"ls\", \"/\", \"/tmp\")\n\nIf you want to run a command in a shell, consider using something like\nthe following – but be aware that not all systems, particularly\nWindows, will have a /bin/sh program:\n\n    exec.Command(\"/bin/sh\", \"-c\", \"ls | grep Awesome\")\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1005",
			"Default": true
		},
		{
			"Name": "SA1007",
			"Doc": "Invalid URL in net/url.Parse\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1007",
			"Default": false
		},
		{
			"Name": "SA1008",
			"Doc": "Non-canonical key in http.Header map\n\nKeys in http.Header maps are canonical, meaning they follow a specific\ncombination of uppercase and lowercase letters. Methods such as\nhttp.Header.Add and http.Header.Del convert inputs into this canonical\nform before manipulating the map.\n\nWhen manipulating http.Header maps directly, as opposed to using the\nprovided methods, care should be taken to stick to canonical form in\norder to avoid inconsistencies. The following piece of code\ndemonstrates one such inconsistency:\n\n    h := http.Header{}\n    h[\"etag\"] = []string{\"1234\"}\n    h.Add(\"etag\", \"5678\")\n    fmt.Println(h)\n\n    // Output:\n    // map[Etag:[5678] etag:[1234]]\n\nThe easiest way of obtaining the canonical form of a key is to use\nhttp.CanonicalHeaderKey.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1008",
			"Default": true
		},
		{
			"Name": "SA1010",
			"Doc": "(*regexp.Regexp).FindAll called with n == 0, which will always return zero results\n\nIf n \u003e= 0, the function returns at most n matches/submatches. To\nreturn all results, specify a negative number.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1010",
			"Default": false
		},
		{
			"Name": "SA1011",
			"Doc": "Various methods in the 'strings' package expect valid UTF-8, but invalid input is provided\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1011",
			"Default": false
		},
		{
			"Name": "SA1012",
			"Doc": "A nil context.Context is being passed to a function, consider using context.TODO instead\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1012",
			"Default": true
		},
		{
			"Name": "SA1013",
			"Doc": "io.Seeker.Seek is being called with the whence constant as the first argument, but it should be the second\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1013",
			"Default": true
		},
		{
			"Name": "SA1014",
			"Doc": "Non-pointer value passed to Unmarshal or Decode\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1014",
			"Default": false
		},
		{
			"Name": "SA1015",
			"Doc": "Using time.Tick in a way that will leak. Consider using time.NewTicker, and only use time.Tick in tests, commands and endless functions\n\nBefore Go 1.23, time.Tickers had to be closed to be able to be garbage\ncollected. Since time.Tick doesn't make it possible to close the underlying\nticker, using it repeatedly would leak memory.\n\nGo 1.23 fixes this by allowing tickers to be collected even if they weren't closed.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1015",
			"Default": false
		},
		{
			"Name": "SA1016",
			"Doc": "Trapping a signal that cannot be trapped\n\nNot all signals can be intercepted by a process. Specifically, on\nUNIX-like systems, the syscall.SIGKILL and syscall.SIGSTOP signals are\nnever passed to the process, but instead handled directly by the\nkernel. It is therefore pointless to try and handle these signals.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1016",
			"Default": true
		},
		{
			"Name": "SA1017",
			"Doc": "Channels used with os/signal.Notify should be buffered\n\nThe os/signal package uses non-blocking channel sends when delivering\nsignals. If the receiving end of the channel isn't ready and the\nchannel is either unbuffered or full, the signal will be dropped. To\navoid missing signals, the channel should be buffered and of the\nappropriate size. For a channel used for notification of just one\nsignal value, a buffer of size 1 is sufficient.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1017",
			"Default": false
		},
		{
			"Name": "SA1018",
			"Doc": "strings.Replace called with n == 0, which does nothing\n\nWith n == 0, zero instances will be replaced. To replace all\ninstances, use a negative number, or use strings.ReplaceAll.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1018",
			"Default": false
		},
		{
			"Name": "SA1020",
			"Doc": "Using an invalid host:port pair with a net.Listen-related function\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1020",
			"Default": false
		},
		{
			"Name": "SA1021",
			"Doc": "Using bytes.Equal to compare two net.IP\n\nA net.IP stores an IPv4 or IPv6 address as a slice of bytes. The\nlength of the slice for an IPv4 address, however, can be either 4 or\n16 bytes long, using different ways of representing IPv4 addresses. In\norder to correctly compare two net.IPs, the net.IP.Equal method should\nbe used, as it takes both representations into account.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1021",
			"Default": false
		},
		{
			"Name": "SA1023",
			"Doc": "Modifying the buffer in an io.Writer implementation\n\nWrite must not modify the slice data, even temporarily.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1023",
			"Default": false
		},
		{
			"Name": "SA1024",
			"Doc": "A string cutset contains duplicate characters\n\nThe strings.TrimLeft and strings.TrimRight functions take cutsets, not\nprefixes. A cutset is treated as a set of characters to remove from a\nstring. For example,\n\n    strings.TrimLeft(\"42133word\", \"1234\")\n\nwill result in the string \"word\" – any characters that are 1, 2, 3 or\n4 are cut from the left of the string.\n\nIn order to remove one string from another, use strings.TrimPrefix instead.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1024",
			"Default": false
		},
		{
			"Name": "SA1025",
			"Doc": "It is not possible to use (*time.Timer).Reset's return value correctly\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1025",
			"Default": false
		},
		{
			"Name": "SA1026",
			"Doc": "Cannot marshal channels or functions\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1026",
			"Default": false
		},
		{
			"Name": "SA1027",
			"Doc": "Atomic access to 64-bit variable must be 64-bit aligned\n\nOn ARM, x86-32, and 32-bit MIPS, it is the caller's responsibility to\narrange for 64-bit alignment of 64-bit words accessed atomically. The\nfirst word in a variable or in an allocated struct, array, or slice\ncan be relied upon to be 64-bit aligned.\n\nYou can use the structlayout tool to inspect the alignment of fields\nin a struct.\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1027",
			"Default": false
		},
		{
			"Name": "SA1028",
			"Doc": "sort.Slice can only be used on slices\n\nThe first argument of sort.Slice must be a slice.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1028",
			"Default": false
		},
		{
			"Name": "SA1029",
			"Doc": "Inappropriate key in call to context.WithValue\n\nThe provided key must be comparable and should not be\nof type string or any other built-in type to avoid collisions between\npackages using context. Users of WithValue should define their own\ntypes for keys.\n\nTo avoid allocating when assigning to an interface{},\ncontext keys often have concrete type struct{}. Alternatively,\nexported context key variables' static type should be a pointer or\ninterface.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1029",
			"Default": false
		},
		{
			"Name": "SA1030",
			"Doc": "Invalid argument in call to a strconv function\n\nThis check validates the format, number base and bit size arguments of\nthe various parsing and formatting functions in strconv.\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1030",
			"Default": false
		},
		{
			"Name": "SA1031",
			"Doc": "Overlapping byte slices passed to an encoder\n\nIn an encoding function of the form Encode(dst, src), dst and\nsrc were found to reference the same memory. This can result in\nsrc bytes being overwritten before they are read, when the encoder\nwrites more than one byte per src byte.\n\nAvailable since\n    2024.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1031",
			"Default": false
		},
		{
			"Name": "SA1032",
			"Doc": "Wrong order of arguments to errors.Is\n\nThe first argument of the function errors.Is is the error\nthat we have and the second argument is the error we're trying to match against.\nFor example:\n\n\tif errors.Is(err, io.EOF) { ... }\n\nThis check detects some cases where the two arguments have been swapped. It\nflags any calls where the first argument is referring to a package-level error\nvariable, such as\n\n\tif errors.Is(io.EOF, err) { /* this is wrong */ }\n\nAvailable since\n    2024.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA1032",
			"Default": false
		},
		{
			"Name": "SA2001",
			"Doc": "Empty critical section, did you mean to defer the unlock?\n\nEmpty critical sections of the kind\n\n    mu.Lock()\n    mu.Unlock()\n\nare very often a typo, and the following was intended instead:\n\n    mu.Lock()\n    defer mu.Unlock()\n\nDo note that sometimes empty critical sections can be useful, as a\nform of signaling to wait on another goroutine. Many times, there are\nsimpler ways of achieving the same effect. When that isn't the case,\nthe code should be amply commented to avoid confusion. Combining such\ncomments with a //lint:ignore directive can be used to suppress this\nrare false positive.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA2001",
			"Default": true
		},
		{
			"Name": "SA2002",
			"Doc": "Called testing.T.FailNow or SkipNow in a goroutine, which isn't allowed\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA2002",
			"Default": false
		},
		{
			"Name": "SA2003",
			"Doc": "Deferred Lock right after locking, likely meant to defer Unlock instead\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA2003",
			"Default": false
		},
		{
			"Name": "SA3000",
			"Doc": "TestMain doesn't call os.Exit, hiding test failures\n\nTest executables (and in turn 'go test') exit with a non-zero status\ncode if any tests failed. When specifying your own TestMain function,\nit is your responsibility to arrange for this, by calling os.Exit with\nthe correct code. The correct code is returned by (*testing.M).Run, so\nthe usual way of implementing TestMain is to end it with\nos.Exit(m.Run()).\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA3000",
			"Default": true
		},
		{
			"Name": "SA3001",
			"Doc": "Assigning to b.N in benchmarks distorts the results\n\nThe testing package dynamically sets b.N to improve the reliability of\nbenchmarks and uses it in computations to determine the duration of a\nsingle operation. Benchmark code must not alter b.N as this would\nfalsify results.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA3001",
			"Default": true
		},
		{
			"Name": "SA4000",
			"Doc": "Binary operator has identical expressions on both sides\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4000",
			"Default": true
		},
		{
			"Name": "SA4001",
			"Doc": "\u0026*x gets simplified to x, it does not copy x\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4001",
			"Default": true
		},
		{
			"Name": "SA4003",
			"Doc": "Comparing unsigned values against negative values is pointless\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4003",
			"Default": true
		},
		{
			"Name": "SA4004",
			"Doc": "The loop exits unconditionally after one iteration\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4004",
			"Default": true
		},
		{
			"Name": "SA4005",
			"Doc": "Field assignment that will never be observed. Did you mean to use a pointer receiver?\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4005",
			"Default": false
		},
		{
			"Name": "SA4006",
			"Doc": "A value assigned to a variable is never read before being overwritten. Forgotten error check or dead code?\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4006",
			"Default": false
		},
		{
			"Name": "SA4008",
			"Doc": "The variable in the loop condition never changes, are you incrementing the wrong variable?\n\nFor example:\n\n\tfor i := 0; i \u003c 10; j++ { ... }\n\nThis may also occur when a loop can only execute once because of unconditional\ncontrol flow that terminates the loop. For example, when a loop body contains an\nunconditional break, return, or panic:\n\n\tfunc f() {\n\t\tpanic(\"oops\")\n\t}\n\tfunc g() {\n\t\tfor i := 0; i \u003c 10; i++ {\n\t\t\t// f unconditionally calls panic, which means \"i\" is\n\t\t\t// never incremented.\n\t\t\tf()\n\t\t}\n\t}\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4008",
			"Default": false
		},
		{
			"Name": "SA4009",
			"Doc": "A function argument is overwritten before its first use\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4009",
			"Default": false
		},
		{
			"Name": "SA4010",
			"Doc": "The result of append will never be observed anywhere\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4010",
			"Default": false
		},
		{
			"Name": "SA4011",
			"Doc": "Break statement with no effect. Did you mean to break out of an outer loop?\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4011",
			"Default": true
		},
		{
			"Name": "SA4012",
			"Doc": "Comparing a value against NaN even though no value is equal to NaN\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4012",
			"Default": false
		},
		{
			"Name": "SA4013",
			"Doc": "Negating a boolean twice (!!b) is the same as writing b. This is either redundant, or a typo.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4013",
			"Default": true
		},
		{
			"Name": "SA4014",
			"Doc": "An if/else if chain has repeated conditions and no side-effects; if the condition didn't match the first time, it won't match the second time, either\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4014",
			"Default": true
		},
		{
			"Name": "SA4015",
			"Doc": "Calling functions like math.Ceil on floats converted from integers doesn't do anything useful\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4015",
			"Default": false
		},
		{
			"Name": "SA4016",
			"Doc": "Certain bitwise operations, such as x ^ 0, do not do anything useful\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4016",
			"Default": true
		},
		{
			"Name": "SA4017",
			"Doc": "Discarding the return values of a function without side effects, making the call pointless\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4017",
			"Default": false
		},
		{
			"Name": "SA4018",
			"Doc": "Self-assignment of variables\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4018",
			"Default": false
		},
		{
			"Name": "SA4019",
			"Doc": "Multiple, identical build constraints in the same file\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4019",
			"Default": true
		},
		{
			"Name": "SA4020",
			"Doc": "Unreachable case clause in a type switch\n\nIn a type switch like the following\n\n    type T struct{}\n    func (T) Read(b []byte) (int, error) { return 0, nil }\n\n    var v any = T{}\n\n    switch v.(type) {\n    case io.Reader:\n        // ...\n    case T:\n        // unreachable\n    }\n\nthe second case clause can never be reached because T implements\nio.Reader and case clauses are evaluated in source order.\n\nAnother example:\n\n    type T struct{}\n    func (T) Read(b []byte) (int, error) { return 0, nil }\n    func (T) Close() error { return nil }\n\n    var v any = T{}\n\n    switch v.(type) {\n    case io.Reader:\n        // ...\n    case io.ReadCloser:\n        // unreachable\n    }\n\nEven though T has a Close method and thus implements io.ReadCloser,\nio.Reader will always match first. The method set of io.Reader is a\nsubset of io.ReadCloser. Thus it is impossible to match the second\ncase without matching the first case.\n\n\nStructurally equivalent interfaces\n\nA special case of the previous example are structurally identical\ninterfaces. Given these declarations\n\n    type T error\n    type V error\n\n    func doSomething() error {\n        err, ok := doAnotherThing()\n        if ok {\n            return T(err)\n        }\n\n        return U(err)\n    }\n\nthe following type switch will have an unreachable case clause:\n\n    switch doSomething().(type) {\n    case T:\n        // ...\n    case V:\n        // unreachable\n    }\n\nT will always match before V because they are structurally equivalent\nand therefore doSomething()'s return value implements both.\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4020",
			"Default": true
		},
		{
			"Name": "SA4022",
			"Doc": "Comparing the address of a variable against nil\n\nCode such as 'if \u0026x == nil' is meaningless, because taking the address of a variable always yields a non-nil pointer.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4022",
			"Default": true
		},
		{
			"Name": "SA4023",
			"Doc": "Impossible comparison of interface value with untyped nil\n\nUnder the covers, interfaces are implemented as two elements, a\ntype T and a value V. V is a concrete value such as an int,\nstruct or pointer, never an interface itself, and has type T. For\ninstance, if we store the int value 3 in an interface, the\nresulting interface value has, schematically, (T=int, V=3). The\nvalue V is also known as the interface's dynamic value, since a\ngiven interface variable might hold different values V (and\ncorresponding types T) during the execution of the program.\n\nAn interface value is nil only if the V and T are both\nunset, (T=nil, V is not set), In particular, a nil interface will\nalways hold a nil type. If we store a nil pointer of type *int\ninside an interface value, the inner type will be *int regardless\nof the value of the pointer: (T=*int, V=nil). Such an interface\nvalue will therefore be non-nil even when the pointer value V\ninside is nil.\n\nThis situation can be confusing, and arises when a nil value is\nstored inside an interface value such as an error return:\n\n    func returnsError() error {\n        var p *MyError = nil\n        if bad() {\n            p = ErrBad\n        }\n        return p // Will always return a non-nil error.\n    }\n\nIf all goes well, the function returns a nil p, so the return\nvalue is an error interface value holding (T=*MyError, V=nil).\nThis means that if the caller compares the returned error to nil,\nit will always look as if there was an error even if nothing bad\nhappened. To return a proper nil error to the caller, the\nfunction must return an explicit nil:\n\n    func returnsError() error {\n        if bad() {\n            return ErrBad\n        }\n        return nil\n    }\n\nIt's a good idea for functions that return errors always to use\nthe error type in their signature (as we did above) rather than a\nconcrete type such as *MyError, to help guarantee the error is\ncreated correctly. As an example, os.Open returns an error even\nthough, if not nil, it's always of concrete type *os.PathError.\n\nSimilar situations to those described here can arise whenever\ninterfaces are used. Just keep in mind that if any concrete value\nhas been stored in the interface, the interface will not be nil.\nFor more information, see The Laws of\nReflection at https://golang.org/doc/articles/laws_of_reflection.html.\n\nThis text has been copied from\nhttps://golang.org/doc/faq#nil_error, licensed under the Creative\nCommons Attribution 3.0 License.\n\nAvailable since\n    2020.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4023",
			"Default": false
		},
		{
			"Name": "SA4024",
			"Doc": "Checking for impossible return value from a builtin function\n\nReturn values of the len and cap builtins cannot be negative.\n\nSee https://golang.org/pkg/builtin/#len and https://golang.org/pkg/builtin/#cap.\n\nExample:\n\n    if len(slice) \u003c 0 {\n        fmt.Println(\"unreachable code\")\n    }\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4024",
			"Default": true
		},
		{
			"Name": "SA4025",
			"Doc": "Integer division of literals that results in zero\n\nWhen dividing two integer constants, the result will\nalso be an integer. Thus, a division such as 2 / 3 results in 0.\nThis is true for all of the following examples:\n\n\t_ = 2 / 3\n\tconst _ = 2 / 3\n\tconst _ float64 = 2 / 3\n\t_ = float64(2 / 3)\n\nStaticcheck will flag such divisions if both sides of the division are\ninteger literals, as it is highly unlikely that the division was\nintended to truncate to zero. Staticcheck will not flag integer\ndivision involving named constants, to avoid noisy positives.\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4025",
			"Default": true
		},
		{
			"Name": "SA4026",
			"Doc": "Go constants cannot express negative zero\n\nIn IEEE 754 floating point math, zero has a sign and can be positive\nor negative. This can be useful in certain numerical code.\n\nGo constants, however, cannot express negative zero. This means that\nthe literals -0.0 and 0.0 have the same ideal value (zero) and\nwill both represent positive zero at runtime.\n\nTo explicitly and reliably create a negative zero, you can use the\nmath.Copysign function: math.Copysign(0, -1).\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4026",
			"Default": true
		},
		{
			"Name": "SA4027",
			"Doc": "(*net/url.URL).Query returns a copy, modifying it doesn't change the URL\n\n(*net/url.URL).Query parses the current value of net/url.URL.RawQuery\nand returns it as a map of type net/url.Values. Subsequent changes to\nthis map will not affect the URL unless the map gets encoded and\nassigned to the URL's RawQuery.\n\nAs a consequence, the following code pattern is an expensive no-op:\nu.Query().Add(key, value).\n\nAvailable since\n    2021.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4027",
			"Default": true
		},
		{
			"Name": "SA4028",
			"Doc": "x % 1 is always zero\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4028",
			"Default": true
		},
		{
			"Name": "SA4029",
			"Doc": "Ineffective attempt at sorting slice\n\nsort.Float64Slice, sort.IntSlice, and sort.StringSlice are\ntypes, not functions. Doing x = sort.StringSlice(x) does nothing,\nespecially not sort any values. The correct usage is\nsort.Sort(sort.StringSlice(x)) or sort.StringSlice(x).Sort(),\nbut there are more convenient helpers, namely sort.Float64s,\nsort.Ints, and sort.Strings.\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4029",
			"Default": true
		},
		{
			"Name": "SA4030",
			"Doc": "Ineffective attempt at generating random number\n\nFunctions in the math/rand package that accept upper limits, such\nas Intn, generate random numbers in the half-open interval [0,n). In\nother words, the generated numbers will be \u003e= 0 and \u003c n – they\ndon't include n. rand.Intn(1) therefore doesn't generate 0\nor 1, it always generates 0.\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4030",
			"Default": true
		},
		{
			"Name": "SA4031",
			"Doc": "Checking never-nil value against nil\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4031",
			"Default": false
		},
		{
			"Name": "SA4032",
			"Doc": "Comparing runtime.GOOS or runtime.GOARCH against impossible value\n\nAvailable since\n    2024.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA4032",
			"Default": true
		},
		{
			"Name": "SA5000",
			"Doc": "Assignment to nil map\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5000",
			"Default": false
		},
		{
			"Name": "SA5001",
			"Doc": "Deferring Close before checking for a possible error\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5001",
			"Default": true
		},
		{
			"Name": "SA5002",
			"Doc": "The empty for loop ('for {}') spins and can block the scheduler\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5002",
			"Default": false
		},
		{
			"Name": "SA5003",
			"Doc": "Defers in infinite loops will never execute\n\nDefers are scoped to the surrounding function, not the surrounding\nblock. In a function that never returns, i.e. one containing an\ninfinite loop, defers will never execute.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5003",
			"Default": true
		},
		{
			"Name": "SA5004",
			"Doc": "'for { select { ...' with an empty default branch spins\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5004",
			"Default": true
		},
		{
			"Name": "SA5005",
			"Doc": "The finalizer references the finalized object, preventing garbage collection\n\nA finalizer is a function associated with an object that runs when the\ngarbage collector is ready to collect said object, that is when the\nobject is no longer referenced by anything.\n\nIf the finalizer references the object, however, it will always remain\nas the final reference to that object, preventing the garbage\ncollector from collecting the object. The finalizer will never run,\nand the object will never be collected, leading to a memory leak. That\nis why the finalizer should instead use its first argument to operate\non the object. That way, the number of references can temporarily go\nto zero before the object is being passed to the finalizer.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5005",
			"Default": false
		},
		{
			"Name": "SA5007",
			"Doc": "Infinite recursive call\n\nA function that calls itself recursively needs to have an exit\ncondition. Otherwise it will recurse forever, until the system runs\nout of memory.\n\nThis issue can be caused by simple bugs such as forgetting to add an\nexit condition. It can also happen \"on purpose\". Some languages have\ntail call optimization which makes certain infinite recursive calls\nsafe to use. Go, however, does not implement TCO, and as such a loop\nshould be used instead.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5007",
			"Default": false
		},
		{
			"Name": "SA5008",
			"Doc": "Invalid struct tag\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5008",
			"Default": true
		},
		{
			"Name": "SA5010",
			"Doc": "Impossible type assertion\n\nSome type assertions can be statically proven to be\nimpossible. This is the case when the method sets of both\narguments of the type assertion conflict with each other, for\nexample by containing the same method with different\nsignatures.\n\nThe Go compiler already applies this check when asserting from an\ninterface value to a concrete type. If the concrete type misses\nmethods from the interface, or if function signatures don't match,\nthen the type assertion can never succeed.\n\nThis check applies the same logic when asserting from one interface to\nanother. If both interface types contain the same method but with\ndifferent signatures, then the type assertion can never succeed,\neither.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5010",
			"Default": false
		},
		{
			"Name": "SA5011",
			"Doc": "Possible nil pointer dereference\n\nA pointer is being dereferenced unconditionally, while\nalso being checked against nil in another place. This suggests that\nthe pointer may be nil and dereferencing it may panic. This is\ncommonly a result of improperly ordered code or missing return\nstatements. Consider the following examples:\n\n    func fn(x *int) {\n        fmt.Println(*x)\n\n        // This nil check is equally important for the previous dereference\n        if x != nil {\n            foo(*x)\n        }\n    }\n\n    func TestFoo(t *testing.T) {\n        x := compute()\n        if x == nil {\n            t.Errorf(\"nil pointer received\")\n        }\n\n        // t.Errorf does not abort the test, so if x is nil, the next line will panic.\n        foo(*x)\n    }\n\nStaticcheck tries to deduce which functions abort control flow.\nFor example, it is aware that a function will not continue\nexecution after a call to panic or log.Fatal. However, sometimes\nthis detection fails, in particular in the presence of\nconditionals. Consider the following example:\n\n    func Log(msg string, level int) {\n        fmt.Println(msg)\n        if level == levelFatal {\n            os.Exit(1)\n        }\n    }\n\n    func Fatal(msg string) {\n        Log(msg, levelFatal)\n    }\n\n    func fn(x *int) {\n        if x == nil {\n            Fatal(\"unexpected nil pointer\")\n        }\n        fmt.Println(*x)\n    }\n\nStaticcheck will flag the dereference of x, even though it is perfectly\nsafe. Staticcheck is not able to deduce that a call to\nFatal will exit the program. For the time being, the easiest\nworkaround is to modify the definition of Fatal like so:\n\n    func Fatal(msg string) {\n        Log(msg, levelFatal)\n        panic(\"unreachable\")\n    }\n\nWe also hard-code functions from common logging packages such as\nlogrus. Please file an issue if we're missing support for a\npopular package.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5011",
			"Default": false
		},
		{
			"Name": "SA5012",
			"Doc": "Passing odd-sized slice to function expecting even size\n\nSome functions that take slices as parameters expect the slices to have an even number of elements. \nOften, these functions treat elements in a slice as pairs. \nFor example, strings.NewReplacer takes pairs of old and new strings, \nand calling it with an odd number of elements would be an error.\n\nAvailable since\n    2020.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA5012",
			"Default": false
		},
		{
			"Name": "SA6000",
			"Doc": "Using regexp.Match or related in a loop, should use regexp.Compile\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6000",
			"Default": false
		},
		{
			"Name": "SA6001",
			"Doc": "Missing an optimization opportunity when indexing maps by byte slices\n\nMap keys must be comparable, which precludes the use of byte slices.\nThis usually leads to using string keys and converting byte slices to\nstrings.\n\nNormally, a conversion of a byte slice to a string needs to copy the data and\ncauses allocations. The compiler, however, recognizes m[string(b)] and\nuses the data of b directly, without copying it, because it knows that\nthe data can't change during the map lookup. This leads to the\ncounter-intuitive situation that\n\n    k := string(b)\n    println(m[k])\n    println(m[k])\n\nwill be less efficient than\n\n    println(m[string(b)])\n    println(m[string(b)])\n\nbecause the first version needs to copy and allocate, while the second\none does not.\n\nFor some history on this optimization, check out commit\nf5f5a8b6209f84961687d993b93ea0d397f5d5bf in the Go repository.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6001",
			"Default": false
		},
		{
			"Name": "SA6002",
			"Doc": "Storing non-pointer values in sync.Pool allocates memory\n\nA sync.Pool is used to avoid unnecessary allocations and reduce the\namount of work the garbage collector has to do.\n\nWhen passing a value that is not a pointer to a function that accepts\nan interface, the value needs to be placed on the heap, which means an\nadditional allocation. Slices are a common thing to put in sync.Pools,\nand they're structs with 3 fields (length, capacity, and a pointer to\nan array). In order to avoid the extra allocation, one should store a\npointer to the slice instead.\n\nSee the comments on https://go-review.googlesource.com/c/go/+/24371\nthat discuss this problem.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6002",
			"Default": false
		},
		{
			"Name": "SA6003",
			"Doc": "Converting a string to a slice of runes before ranging over it\n\nYou may want to loop over the runes in a string. Instead of converting\nthe string to a slice of runes and looping over that, you can loop\nover the string itself. That is,\n\n    for _, r := range s {}\n\nand\n\n    for _, r := range []rune(s) {}\n\nwill yield the same values. The first version, however, will be faster\nand avoid unnecessary memory allocations.\n\nDo note that if you are interested in the indices, ranging over a\nstring and over a slice of runes will yield different indices. The\nfirst one yields byte offsets, while the second one yields indices in\nthe slice of runes.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6003",
			"Default": false
		},
		{
			"Name": "SA6005",
			"Doc": "Inefficient string comparison with strings.ToLower or strings.ToUpper\n\nConverting two strings to the same case and comparing them like so\n\n    if strings.ToLower(s1) == strings.ToLower(s2) {\n        ...\n    }\n\nis significantly more expensive than comparing them with\nstrings.EqualFold(s1, s2). This is due to memory usage as well as\ncomputational complexity.\n\nstrings.ToLower will have to allocate memory for the new strings, as\nwell as convert both strings fully, even if they differ on the very\nfirst byte. strings.EqualFold, on the other hand, compares the strings\none character at a time. It doesn't need to create two intermediate\nstrings and can return as soon as the first non-matching character has\nbeen found.\n\nFor a more in-depth explanation of this issue, see\nhttps://blog.digitalocean.com/how-to-efficiently-compare-strings-in-go/\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6005",
			"Default": true
		},
		{
			"Name": "SA6006",
			"Doc": "Using io.WriteString to write []byte\n\nUsing io.WriteString to write a slice of bytes, as in\n\n    io.WriteString(w, string(b))\n\nis both unnecessary and inefficient. Converting from []byte to string\nhas to allocate and copy the data, and we could simply use w.Write(b)\ninstead.\n\nAvailable since\n    2024.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA6006",
			"Default": true
		},
		{
			"Name": "SA9001",
			"Doc": "Defers in range loops may not run when you expect them to\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9001",
			"Default": false
		},
		{
			"Name": "SA9002",
			"Doc": "Using a non-octal os.FileMode that looks like it was meant to be in octal.\n\nAvailable since\n    2017.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9002",
			"Default": true
		},
		{
			"Name": "SA9003",
			"Doc": "Empty body in an if or else branch\n\nAvailable since\n    2017.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9003",
			"Default": false
		},
		{
			"Name": "SA9004",
			"Doc": "Only the first constant has an explicit type\n\nIn a constant declaration such as the following:\n\n    const (\n        First byte = 1\n        Second     = 2\n    )\n\nthe constant Second does not have the same type as the constant First.\nThis construct shouldn't be confused with\n\n    const (\n        First byte = iota\n        Second\n    )\n\nwhere First and Second do indeed have the same type. The type is only\npassed on when no explicit value is assigned to the constant.\n\nWhen declaring enumerations with explicit values it is therefore\nimportant not to write\n\n    const (\n          EnumFirst EnumType = 1\n          EnumSecond         = 2\n          EnumThird          = 3\n    )\n\nThis discrepancy in types can cause various confusing behaviors and\nbugs.\n\n\nWrong type in variable declarations\n\nThe most obvious issue with such incorrect enumerations expresses\nitself as a compile error:\n\n    package pkg\n\n    const (\n        EnumFirst  uint8 = 1\n        EnumSecond       = 2\n    )\n\n    func fn(useFirst bool) {\n        x := EnumSecond\n        if useFirst {\n            x = EnumFirst\n        }\n    }\n\nfails to compile with\n\n    ./const.go:11:5: cannot use EnumFirst (type uint8) as type int in assignment\n\n\nLosing method sets\n\nA more subtle issue occurs with types that have methods and optional\ninterfaces. Consider the following:\n\n    package main\n\n    import \"fmt\"\n\n    type Enum int\n\n    func (e Enum) String() string {\n        return \"an enum\"\n    }\n\n    const (\n        EnumFirst  Enum = 1\n        EnumSecond      = 2\n    )\n\n    func main() {\n        fmt.Println(EnumFirst)\n        fmt.Println(EnumSecond)\n    }\n\nThis code will output\n\n    an enum\n    2\n\nas EnumSecond has no explicit type, and thus defaults to int.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9004",
			"Default": true
		},
		{
			"Name": "SA9005",
			"Doc": "Trying to marshal a struct with no public fields nor custom marshaling\n\nThe encoding/json and encoding/xml packages only operate on exported\nfields in structs, not unexported ones. It is usually an error to try\nto (un)marshal structs that only consist of unexported fields.\n\nThis check will not flag calls involving types that define custom\nmarshaling behavior, e.g. via MarshalJSON methods. It will also not\nflag empty structs.\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9005",
			"Default": false
		},
		{
			"Name": "SA9006",
			"Doc": "Dubious bit shifting of a fixed size integer value\n\nBit shifting a value past its size will always clear the value.\n\nFor instance:\n\n    v := int8(42)\n    v \u003e\u003e= 8\n\nwill always result in 0.\n\nThis check flags bit shifting operations on fixed size integer values only.\nThat is, int, uint and uintptr are never flagged to avoid potential false\npositives in somewhat exotic but valid bit twiddling tricks:\n\n    // Clear any value above 32 bits if integers are more than 32 bits.\n    func f(i int) int {\n        v := i \u003e\u003e 32\n        v = v \u003c\u003c 32\n        return i-v\n    }\n\nAvailable since\n    2020.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9006",
			"Default": true
		},
		{
			"Name": "SA9007",
			"Doc": "Deleting a directory that shouldn't be deleted\n\nIt is virtually never correct to delete system directories such as\n/tmp or the user's home directory. However, it can be fairly easy to\ndo by mistake, for example by mistakenly using os.TempDir instead\nof ioutil.TempDir, or by forgetting to add a suffix to the result\nof os.UserHomeDir.\n\nWriting\n\n    d := os.TempDir()\n    defer os.RemoveAll(d)\n\nin your unit tests will have a devastating effect on the stability of your system.\n\nThis check flags attempts at deleting the following directories:\n\n- os.TempDir\n- os.UserCacheDir\n- os.UserConfigDir\n- os.UserHomeDir\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9007",
			"Default": false
		},
		{
			"Name": "SA9008",
			"Doc": "else branch of a type assertion is probably not reading the right value\n\nWhen declaring variables as part of an if statement (like in 'if\nfoo := ...; foo {'), the same variables will also be in the scope of\nthe else branch. This means that in the following example\n\n    if x, ok := x.(int); ok {\n        // ...\n    } else {\n        fmt.Printf(\"unexpected type %T\", x)\n    }\n\nx in the else branch will refer to the x from x, ok\n:=; it will not refer to the x that is being type-asserted. The\nresult of a failed type assertion is the zero value of the type that\nis being asserted to, so x in the else branch will always have the\nvalue 0 and the type int.\n\nAvailable since\n    2022.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9008",
			"Default": false
		},
		{
			"Name": "SA9009",
			"Doc": "Ineffectual Go compiler directive\n\nA potential Go compiler directive was found, but is ineffectual as it begins\nwith whitespace.\n\nAvailable since\n    2024.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#SA9009",
			"Default": true
		},
		{
			"Name": "ST1000",
			"Doc": "Incorrect or missing package comment\n\nPackages must have a package comment that is formatted according to\nthe guidelines laid out in\nhttps://go.dev/wiki/CodeReviewComments#package-comments.\n\nAvailable since\n    2019.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1000",
			"Default": false
		},
		{
			"Name": "ST1001",
			"Doc": "Dot imports are discouraged\n\nDot imports that aren't in external test packages are discouraged.\n\nThe dot_import_whitelist option can be used to whitelist certain\nimports.\n\nQuoting Go Code Review Comments:\n\n\u003e The import . form can be useful in tests that, due to circular\n\u003e dependencies, cannot be made part of the package being tested:\n\u003e \n\u003e     package foo_test\n\u003e \n\u003e     import (\n\u003e         \"bar/testutil\" // also imports \"foo\"\n\u003e         . \"foo\"\n\u003e     )\n\u003e \n\u003e In this case, the test file cannot be in package foo because it\n\u003e uses bar/testutil, which imports foo. So we use the import .\n\u003e form to let the file pretend to be part of package foo even though\n\u003e it is not. Except for this one case, do not use import . in your\n\u003e programs. It makes the programs much harder to read because it is\n\u003e unclear whether a name like Quux is a top-level identifier in the\n\u003e current package or in an imported package.\n\nAvailable since\n    2019.1\n\nOptions\n    dot_import_whitelist\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1001",
			"Default": false
		},
		{
			"Name": "ST1003",
			"Doc": "Poorly chosen identifier\n\nIdentifiers, such as variable and package names, follow certain rules.\n\nSee the following links for details:\n\n- https://go.dev/doc/effective_go#package-names\n- https://go.dev/doc/effective_go#mixed-caps\n- https://go.dev/wiki/CodeReviewComments#initialisms\n- https://go.dev/wiki/CodeReviewComments#variable-names\n\nAvailable since\n    2019.1, non-default\n\nOptions\n    initialisms\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1003",
			"Default": false
		},
		{
			"Name": "ST1005",
			"Doc": "Incorrectly formatted error string\n\nError strings follow a set of guidelines to ensure uniformity and good\ncomposability.\n\nQuoting Go Code Review Comments:\n\n\u003e Error strings should not be capitalized (unless beginning with\n\u003e proper nouns or acronyms) or end with punctuation, since they are\n\u003e usually printed following other context. That is, use\n\u003e fmt.Errorf(\"something bad\") not fmt.Errorf(\"Something bad\"), so\n\u003e that log.Printf(\"Reading %s: %v\", filename, err) formats without a\n\u003e spurious capital letter mid-message.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1005",
			"Default": false
		},
		{
			"Name": "ST1006",
			"Doc": "Poorly chosen receiver name\n\nQuoting Go Code Review Comments:\n\n\u003e The name of a method's receiver should be a reflection of its\n\u003e identity; often a one or two letter abbreviation of its type\n\u003e suffices (such as \"c\" or \"cl\" for \"Client\"). Don't use generic\n\u003e names such as \"me\", \"this\" or \"self\", identifiers typical of\n\u003e object-oriented languages that place more emphasis on methods as\n\u003e opposed to functions. The name need not be as descriptive as that\n\u003e of a method argument, as its role is obvious and serves no\n\u003e documentary purpose. It can be very short as it will appear on\n\u003e almost every line of every method of the type; familiarity admits\n\u003e brevity. Be consistent, too: if you call the receiver \"c\" in one\n\u003e method, don't call it \"cl\" in another.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1006",
			"Default": false
		},
		{
			"Name": "ST1008",
			"Doc": "A function's error value should be its last return value\n\nA function's error value should be its last return value.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1008",
			"Default": false
		},
		{
			"Name": "ST1011",
			"Doc": "Poorly chosen name for variable of type time.Duration\n\ntime.Duration values represent an amount of time, which is represented\nas a count of nanoseconds. An expression like 5 * time.Microsecond\nyields the value 5000. It is therefore not appropriate to suffix a\nvariable of type time.Duration with any time unit, such as Msec or\nMilli.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1011",
			"Default": false
		},
		{
			"Name": "ST1012",
			"Doc": "Poorly chosen name for error variable\n\nError variables that are part of an API should be called errFoo or\nErrFoo.\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1012",
			"Default": false
		},
		{
			"Name": "ST1013",
			"Doc": "Should use constants for HTTP error codes, not magic numbers\n\nHTTP has a tremendous number of status codes. While some of those are\nwell known (200, 400, 404, 500), most of them are not. The net/http\npackage provides constants for all status codes that are part of the\nvarious specifications. It is recommended to use these constants\ninstead of hard-coding magic numbers, to vastly improve the\nreadability of your code.\n\nAvailable since\n    2019.1\n\nOptions\n    http_status_code_whitelist\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1013",
			"Default": false
		},
		{
			"Name": "ST1015",
			"Doc": "A switch's default case should be the first or last case\n\nAvailable since\n    2019.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1015",
			"Default": false
		},
		{
			"Name": "ST1016",
			"Doc": "Use consistent method receiver names\n\nAvailable since\n    2019.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1016",
			"Default": false
		},
		{
			"Name": "ST1017",
			"Doc": "Don't use Yoda conditions\n\nYoda conditions are conditions of the kind 'if 42 == x', where the\nliteral is on the left side of the comparison. These are a common\nidiom in languages in which assignment is an expression, to avoid bugs\nof the kind 'if (x = 42)'. In Go, which doesn't allow for this kind of\nbug, we prefer the more idiomatic 'if x == 42'.\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1017",
			"Default": false
		},
		{
			"Name": "ST1018",
			"Doc": "Avoid zero-width and control characters in string literals\n\nAvailable since\n    2019.2\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1018",
			"Default": false
		},
		{
			"Name": "ST1019",
			"Doc": "Importing the same package multiple times\n\nGo allows importing the same package multiple times, as long as\ndifferent import aliases are being used. That is, the following\nbit of code is valid:\n\n    import (\n        \"fmt\"\n        fumpt \"fmt\"\n        format \"fmt\"\n    )\n\nHowever, this is very rarely done on purpose. Usually, it is a\nsign of code that got refactored, accidentally adding duplicate\nimport statements. It is also a rarely known feature, which may\ncontribute to confusion.\n\nDo note that sometimes, this feature may be used\nintentionally (see for example\nhttps://github.com/golang/go/commit/3409ce39bfd7584523b7a8c150a310cea92d879d)\n– if you want to allow this pattern in your code base, you're\nadvised to disable this check.\n\nIt is acceptable to import the same package twice if one of the imports\nuses the blank identifier. This is allowed in order to increase\nresilience against erroneous changes when using the same package for its\nside effects as well as its exported API.\n\nAvailable since\n    2020.1\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1019",
			"Default": false
		},
		{
			"Name": "ST1020",
			"Doc": "The documentation of an exported function should start with the function's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1020",
			"Default": false
		},
		{
			"Name": "ST1021",
			"Doc": "The documentation of an exported type should start with type's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1021",
			"Default": false
		},
		{
			"Name": "ST1022",
			"Doc": "The documentation of an exported variable or constant should start with variable's name\n\nDoc comments work best as complete sentences, which\nallow a wide variety of automated presentations. The first sentence\nshould be a one-sentence summary that starts with the name being\ndeclared.\n\nIf every doc comment begins with the name of the item it describes,\nyou can use the doc subcommand of the go tool and run the output\nthrough grep.\n\nSee https://go.dev/doc/effective_go#commentary for more\ninformation on how to write good documentation.\n\nAvailable since\n    2020.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#ST1022",
			"Default": false
		},
		{
			"Name": "ST1023",
			"Doc": "Redundant type in variable declaration\n\nAvailable since\n    2021.1, non-default\n",
			"URL": "https://staticcheck.dev/docs/checks/#",
			"Default": false
		},
		{
			"Name": "any",
			"Doc": "replace interface{} with any\n\nThe any analyzer suggests replacing uses of the empty interface type,\n`interface{}`, with the `any` alias, which was introduced in Go 1.18.\nThis is a purely stylistic change that makes code more readable.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#any",
			"Default": true
		},
		{
			"Name": "appendclipped",
			"Doc": "simplify append chains using slices.Concat\n\nThe appendclipped analyzer suggests replacing chains of append calls with a\nsingle call to slices.Concat, which was added in Go 1.21. For example,\nappend(append(s, s1...), s2...) would be simplified to slices.Concat(s, s1, s2).\n\nIn the simple case of appending to a newly allocated slice, such as\nappend([]T(nil), s...), the analyzer suggests the more concise slices.Clone(s).\nFor byte slices, it will prefer bytes.Clone if the \"bytes\" package is\nalready imported.\n\nThis fix is only applied when the base of the append tower is a\n\"clipped\" slice, meaning its length and capacity are equal (e.g.\nx[:0:0] or []T{}). This is to avoid changing program behavior by\neliminating intended side effects on the base slice's underlying\narray.\n\nThis analyzer is currently disabled by default as the\ntransformation does not preserve the nilness of the base slice in\nall cases; see https://go.dev/issue/73557.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#appendclipped",
			"Default": false
		},
		{
			"Name": "appends",
			"Doc": "check for missing values after append\n\nThis checker reports calls to append that pass\nno values to be appended to the slice.\n\n\ts := []string{\"a\", \"b\", \"c\"}\n\t_ = append(s)\n\nSuch calls are always no-ops and often indicate an\nunderlying mistake.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/appends",
			"Default": true
		},
		{
			"Name": "asmdecl",
			"Doc": "report mismatches between assembly files and Go declarations",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/asmdecl",
			"Default": true
		},
		{
			"Name": "assign",
			"Doc": "check for useless assignments\n\nThis checker reports assignments of the form x = x or a[i] = a[i].\nThese are almost always useless, and even when they aren't they are\nusually a mistake.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/assign",
			"Default": true
		},
		{
			"Name": "atomic",
			"Doc": "check for common mistakes using the sync/atomic package\n\nThe atomic checker looks for assignment statements of the form:\n\n\tx = atomic.AddUint64(\u0026x, 1)\n\nwhich are not atomic.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomic",
			"Default": true
		},
		{
			"Name": "atomicalign",
			"Doc": "check for non-64-bits-aligned arguments to sync/atomic functions",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/atomicalign",
			"Default": true
		},
		{
			"Name": "atomictypes",
			"Doc": "replace basic types in sync/atomic calls with atomic types\n\nThe atomictypes analyzer suggests replacing the primitive sync/atomic functions with\nthe strongly typed atomic wrapper types introduced in Go1.19 (e.g.\natomic.Int32). For example,\n\n\tvar x int32\n\tatomic.AddInt32(\u0026x, 1)\n\nwould become\n\n\tvar x atomic.Int32\n\tx.Add(1)\n\nThe atomic types are safer because they don't allow non-atomic access, which is\na common source of bugs. These types also resolve memory alignment issues that\nplagued the old atomic functions on 32-bit architectures.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#atomictypes",
			"Default": true
		},
		{
			"Name": "bloop",
			"Doc": "replace for-range over b.N with b.Loop\n\nThe bloop analyzer suggests replacing benchmark loops of the form\n`for i := 0; i \u003c b.N; i++` or `for range b.N` with the more modern\n`for b.Loop()`, which was added in Go 1.24.\n\nThis change makes benchmark code more readable and also removes the need for\nmanual timer control, so any preceding calls to b.StartTimer, b.StopTimer,\nor b.ResetTimer within the same function will also be removed.\n\nCaveats: The b.Loop() method is designed to prevent the compiler from\noptimizing away the benchmark loop, which can occasionally result in\nslower execution due to increased allocations in some specific cases.\nSince its fix may change the performance of nanosecond-scale benchmarks,\nbloop is disabled by default in the `go fix` analyzer suite; see golang/go#74967.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#bloop",
			"Default": true
		},
		{
			"Name": "bools",
			"Doc": "check for common mistakes involving boolean operators",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/bools",
			"Default": true
		},
		{
			"Name": "buildtag",
			"Doc": "check //go:build and // +build directives",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/buildtag",
			"Default": true
		},
		{
			"Name": "cgocall",
			"Doc": "detect some violations of the cgo pointer passing rules\n\nCheck for invalid cgo pointer passing.\nThis looks for code that uses cgo to call C code passing values\nwhose types are almost always invalid according to the cgo pointer\nsharing rules.\nSpecifically, it warns about attempts to pass a Go chan, map, func,\nor slice to C, either directly, or via a pointer, array, or struct.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/cgocall",
			"Default": true
		},
		{
			"Name": "composites",
			"Doc": "check for unkeyed composite literals\n\nThis analyzer reports a diagnostic for composite literals of struct\ntypes imported from another package that do not use the field-keyed\nsyntax. Such literals are fragile because the addition of a new field\n(even if unexported) to the struct will cause compilation to fail.\n\nAs an example,\n\n\terr = \u0026net.DNSConfigError{err}\n\nshould be replaced by:\n\n\terr = \u0026net.DNSConfigError{Err: err}\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/composite",
			"Default": true
		},
		{
			"Name": "copylocks",
			"Doc": "check for locks erroneously passed by value\n\nInadvertently copying a value containing a lock, such as sync.Mutex or\nsync.WaitGroup, may cause both copies to malfunction. Generally such\nvalues should be referred to through a pointer.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/copylock",
			"Default": true
		},
		{
			"Name": "deepequalerrors",
			"Doc": "check for calls of reflect.DeepEqual on error values\n\nThe deepequalerrors checker looks for calls of the form:\n\n    reflect.DeepEqual(err1, err2)\n\nwhere err1 and err2 are errors. Using reflect.DeepEqual to compare\nerrors is discouraged.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/deepequalerrors",
			"Default": true
		},
		{
			"Name": "defers",
			"Doc": "report common mistakes in defer statements\n\nThe defers analyzer reports a diagnostic when a defer statement would\nresult in a non-deferred call to time.Since, as experience has shown\nthat this is nearly always a mistake.\n\nFor example:\n\n\tstart := time.Now()\n\t...\n\tdefer recordLatency(time.Since(start)) // error: call to time.Since is not deferred\n\nThe correct code is:\n\n\tdefer func() { recordLatency(time.Since(start)) }()",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/defers",
			"Default": true
		},
		{
			"Name": "deprecated",
			"Doc": "check for use of deprecated identifiers\n\nThe deprecated analyzer looks for deprecated symbols and package\nimports.\n\nSee https://go.dev/wiki/Deprecated to learn about Go's convention\nfor documenting and signaling deprecated identifiers.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/deprecated",
			"Default": true
		},
		{
			"Name": "directive",
			"Doc": "check Go toolchain directives such as //go:debug\n\nThis analyzer checks for problems with known Go toolchain directives\nin all Go source files in a package directory, even those excluded by\n//go:build constraints, and all non-Go source files too.\n\nFor //go:debug (see https://go.dev/doc/godebug), the analyzer checks\nthat the directives are placed only in Go source files, only above the\npackage comment, and only in package main or *_test.go files.\n\nSupport for other known directives may be added in the future.\n\nThis analyzer does not check //go:build, which is handled by the\nbuildtag analyzer.\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/directive",
			"Default": true
		},
		{
			"Name": "embed",
			"Doc": "check //go:embed directive usage\n\nThis analyzer checks that the embed package is imported if //go:embed\ndirectives are present, providing a suggested fix to add the import if\nit is missing.\n\nThis analyzer also checks that //go:embed directives precede the\ndeclaration of a single variable.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/embeddirective",
			"Default": true
		},
		{
			"Name": "errorsas",
			"Doc": "report passing non-pointer or non-error values to errors.As\n\nThe errorsas analyzer reports calls to errors.As where the type\nof the second argument is not a pointer to a type implementing error.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/errorsas",
			"Default": true
		},
		{
			"Name": "errorsastype",
			"Doc": "replace errors.As with errors.AsType[T]\n\nThis analyzer suggests fixes to simplify uses of [errors.As] of\nthis form:\n\n\tvar myerr *MyErr\n\tif errors.As(err, \u0026myerr) {\n\t\thandle(myerr)\n\t}\n\nby using the less error-prone generic [errors.AsType] function,\nintroduced in Go 1.26:\n\n\tif myerr, ok := errors.AsType[*MyErr](err); ok {\n\t\thandle(myerr)\n\t}\n\nThe fix is only offered if the var declaration has the form shown and\nthere are no uses of myerr outside the if statement.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#errorsastype",
			"Default": true
		},
		{
			"Name": "fieldalignment",
			"Doc": "find structs that would use less memory if their fields were sorted\n\nThis analyzer finds structs that can be rearranged to use less memory, and provides\na suggested edit with the most compact order.\n\nNote that there are two different diagnostics reported. One checks struct size,\nand the other reports \"pointer bytes\" used. Pointer bytes is how many bytes of the\nobject that the garbage collector has to potentially scan for pointers, for example:\n\n\tstruct { uint32; string }\n\nhave 16 pointer bytes because the garbage collector has to scan up through the string's\ninner pointer.\n\n\tstruct { string; *uint32 }\n\nhas 24 pointer bytes because it has to scan further through the *uint32.\n\n\tstruct { string; uint32 }\n\nhas 8 because it can stop immediately after the string pointer.\n\nBe aware that the most compact order is not always the most efficient.\nIn rare cases it may cause two variables each updated by its own goroutine\nto occupy the same CPU cache line, inducing a form of memory contention\nknown as \"false sharing\" that slows down both goroutines.\n\nUnlike most analyzers, which report likely mistakes, the diagnostics\nproduced by fieldanalyzer very rarely indicate a significant problem,\nso the analyzer is not included in typical suites such as vet or\ngopls. Use this standalone command to run it on your code:\n\n   $ go install golang.org/x/tools/go/analysis/passes/fieldalignment/cmd/fieldalignment@latest\n   $ fieldalignment [packages]\n\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/fieldalignment",
			"Default": false
		},
		{
			"Name": "fillreturns",
			"Doc": "suggest fixes for errors due to an incorrect number of return values\n\nThis checker provides suggested fixes for type errors of the\ntype \"wrong number of return values (want %d, got %d)\". For example:\n\n\tfunc m() (int, string, *bool, error) {\n\t\treturn\n\t}\n\nwill turn into\n\n\tfunc m() (int, string, *bool, error) {\n\t\treturn 0, \"\", nil, nil\n\t}\n\nThis functionality is similar to https://github.com/sqs/goreturns.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/fillreturns",
			"Default": true
		},
		{
			"Name": "fmtappendf",
			"Doc": "replace []byte(fmt.Sprintf) with fmt.Appendf\n\nThe fmtappendf analyzer suggests replacing `[]byte(fmt.Sprintf(...))` with\n`fmt.Appendf(nil, ...)`. This avoids the intermediate allocation of a string\nby Sprintf, making the code more efficient. The suggestion also applies to\nfmt.Sprint and fmt.Sprintln.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#fmtappendf",
			"Default": true
		},
		{
			"Name": "forvar",
			"Doc": "remove redundant re-declaration of loop variables\n\nThe forvar analyzer removes unnecessary shadowing of loop variables.\nBefore Go 1.22, it was common to write `for _, x := range s { x := x ... }`\nto create a fresh variable for each iteration. Go 1.22 changed the semantics\nof `for` loops, making this pattern redundant. This analyzer removes the\nunnecessary `x := x` statement.\n\nThis fix only applies to `range` loops.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#forvar",
			"Default": true
		},
		{
			"Name": "framepointer",
			"Doc": "report assembly that clobbers the frame pointer before saving it",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/framepointer",
			"Default": true
		},
		{
			"Name": "hostport",
			"Doc": "check format of addresses passed to net.Dial\n\nThis analyzer flags code that produce network address strings using\nfmt.Sprintf, as in this example:\n\n    addr := fmt.Sprintf(\"%s:%d\", host, 12345) // \"will not work with IPv6\"\n    ...\n    conn, err := net.Dial(\"tcp\", addr)       // \"when passed to dial here\"\n\nThe analyzer suggests a fix to use the correct approach, a call to\nnet.JoinHostPort:\n\n    addr := net.JoinHostPort(host, \"12345\")\n    ...\n    conn, err := net.Dial(\"tcp\", addr)\n\nA similar diagnostic and fix are produced for a format string of \"%s:%s\".\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/hostport",
			"Default": true
		},
		{
			"Name": "httpresponse",
			"Doc": "check for mistakes using HTTP responses\n\nA common mistake when using the net/http package is to defer a function\ncall to close the http.Response Body before checking the error that\ndetermines whether the response is valid:\n\n\tresp, err := http.Head(url)\n\tdefer resp.Body.Close()\n\tif err != nil {\n\t\tlog.Fatal(err)\n\t}\n\t// (defer statement belongs here)\n\nThis checker helps uncover latent nil dereference bugs by reporting a\ndiagnostic for such mistakes.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/httpresponse",
			"Default": true
		},
		{
			"Name": "ifaceassert",
			"Doc": "detect impossible interface-to-interface type assertions\n\nThis checker flags type assertions v.(T) and corresponding type-switch cases\nin which the static type V of v is an interface that cannot possibly implement\nthe target interface T. This occurs when V and T contain methods with the same\nname but different signatures. Example:\n\n\tvar v interface {\n\t\tRead()\n\t}\n\t_ = v.(io.Reader)\n\nThe Read method in v has a different signature than the Read method in\nio.Reader, so this assertion cannot succeed.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/ifaceassert",
			"Default": true
		},
		{
			"Name": "infertypeargs",
			"Doc": "check for unnecessary type arguments in call expressions\n\nExplicit type arguments may be omitted from call expressions if they can be\ninferred from function arguments, or from other type arguments:\n\n\tfunc f[T any](T) {}\n\t\n\tfunc _() {\n\t\tf[string](\"foo\") // string could be inferred\n\t}\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/infertypeargs",
			"Default": true
		},
		{
			"Name": "inline",
			"Doc": "apply fixes based on 'go:fix inline' comment directives\n\nThe inline analyzer inlines functions and constants that are marked for inlining.\n\n## Functions\n\nGiven a function that is marked for inlining, like this one:\n\n\t//go:fix inline\n\tfunc Square(x int) int { return Pow(x, 2) }\n\nthis analyzer will recommend that calls to the function elsewhere, in the same\nor other packages, should be inlined.\n\nInlining can be used to move off of a deprecated function:\n\n\t// Deprecated: prefer Pow(x, 2).\n\t//go:fix inline\n\tfunc Square(x int) int { return Pow(x, 2) }\n\nIt can also be used to move off of an obsolete package,\nas when the import path has changed or a higher major version is available:\n\n\tpackage pkg\n\n\timport pkg2 \"pkg/v2\"\n\n\t//go:fix inline\n\tfunc F() { pkg2.F(nil) }\n\nReplacing a call pkg.F() by pkg2.F(nil) can have no effect on the program,\nso this mechanism provides a low-risk way to update large numbers of calls.\nWe recommend, where possible, expressing the old API in terms of the new one\nto enable automatic migration.\n\nThe inliner takes care to avoid behavior changes, even subtle ones,\nsuch as changes to the order in which argument expressions are\nevaluated. When it cannot safely eliminate all parameter variables,\nit may introduce a \"binding declaration\" of the form\n\n\tvar params = args\n\nto evaluate argument expressions in the correct order and bind them to\nparameter variables. Since the resulting code transformation may be\nstylistically suboptimal, such inlinings may be disabled by specifying\nthe -inline.allow_binding_decl=false flag to the analyzer driver.\n\n(In cases where it is not safe to \"reduce\" a call—that is, to replace\na call f(x) by the body of function f, suitably substituted—the\ninliner machinery is capable of replacing f by a function literal,\nfunc(){...}(). However, the inline analyzer discards all such\n\"literalizations\" unconditionally, again on grounds of style.)\n\n## Constants\n\nGiven a constant that is marked for inlining, like this one:\n\n\t//go:fix inline\n\tconst Ptr = Pointer\n\nthis analyzer will recommend that uses of Ptr should be replaced with Pointer.\n\nAs with functions, inlining can be used to replace deprecated constants and\nconstants in obsolete packages.\n\nA constant definition can be marked for inlining only if it refers to another\nnamed constant.\n\nThe \"//go:fix inline\" comment must appear before a single const declaration on its own,\nas above; before a const declaration that is part of a group, as in this case:\n\n\tconst (\n\t   C = 1\n\t   //go:fix inline\n\t   Ptr = Pointer\n\t)\n\nor before a group, applying to every constant in the group:\n\n\t//go:fix inline\n\tconst (\n\t\tPtr = Pointer\n\t    Val = Value\n\t)\n\nThe proposal https://go.dev/issue/32816 introduces the \"//go:fix inline\" directives.\n\nYou can use this command to apply inline fixes en masse:\n\n\t$ go run golang.org/x/tools/go/analysis/passes/inline/cmd/inline@latest -fix ./...",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/inline",
			"Default": true
		},
		{
			"Name": "loopclosure",
			"Doc": "check references to loop variables from within nested functions\n\nThis analyzer reports places where a function literal references the\niteration variable of an enclosing loop, and the loop calls the function\nin such a way (e.g. with go or defer) that it may outlive the loop\niteration and possibly observe the wrong value of the variable.\n\nNote: An iteration variable can only outlive a loop iteration in Go versions \u003c=1.21.\nIn Go 1.22 and later, the loop variable lifetimes changed to create a new\niteration variable per loop iteration. (See go.dev/issue/60078.)\n\nIn this example, all the deferred functions run after the loop has\ncompleted, so all observe the final value of v [\u003cgo1.22].\n\n\tfor _, v := range list {\n\t    defer func() {\n\t        use(v) // incorrect\n\t    }()\n\t}\n\nOne fix is to create a new variable for each iteration of the loop:\n\n\tfor _, v := range list {\n\t    v := v // new var per iteration\n\t    defer func() {\n\t        use(v) // ok\n\t    }()\n\t}\n\nAfter Go version 1.22, the previous two for loops are equivalent\nand both are correct.\n\nThe next example uses a go statement and has a similar problem [\u003cgo1.22].\nIn addition, it has a data race because the loop updates v\nconcurrent with the goroutines accessing it.\n\n\tfor _, v := range elem {\n\t    go func() {\n\t        use(v)  // incorrect, and a data race\n\t    }()\n\t}\n\nA fix is the same as before. The checker also reports problems\nin goroutines started by golang.org/x/sync/errgroup.Group.\nA hard-to-spot variant of this form is common in parallel tests:\n\n\tfunc Test(t *testing.T) {\n\t    for _, test := range tests {\n\t        t.Run(test.name, func(t *testing.T) {\n\t            t.Parallel()\n\t            use(test) // incorrect, and a data race\n\t        })\n\t    }\n\t}\n\nThe t.Parallel() call causes the rest of the function to execute\nconcurrent with the loop [\u003cgo1.22].\n\nThe analyzer reports references only in the last statement,\nas it is not deep enough to understand the effects of subsequent\nstatements that might render the reference benign.\n(\"Last statement\" is defined recursively in compound\nstatements such as if, switch, and select.)\n\nSee: https://golang.org/doc/go_faq.html#closures_and_goroutines",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/loopclosure",
			"Default": true
		},
		{
			"Name": "lostcancel",
			"Doc": "check cancel func returned by context.WithCancel is called\n\nThe cancellation function returned by context.WithCancel, WithTimeout,\nWithDeadline and variants such as WithCancelCause must be called,\nor the new context will remain live until its parent context is cancelled.\n(The background context is never cancelled.)",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/lostcancel",
			"Default": true
		},
		{
			"Name": "maprange",
			"Doc": "checks for unnecessary calls to maps.Keys and maps.Values in range statements\n\nConsider a loop written like this:\n\n\tfor val := range maps.Values(m) {\n\t\tfmt.Println(val)\n\t}\n\nThis should instead be written without the call to maps.Values:\n\n\tfor _, val := range m {\n\t\tfmt.Println(val)\n\t}\n\ngolang.org/x/exp/maps returns slices for Keys/Values instead of iterators,\nbut unnecessary calls should similarly be removed:\n\n\tfor _, key := range maps.Keys(m) {\n\t\tfmt.Println(key)\n\t}\n\nshould be rewritten as:\n\n\tfor key := range m {\n\t\tfmt.Println(key)\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/maprange",
			"Default": true
		},
		{
			"Name": "mapsloop",
			"Doc": "replace explicit loops over maps with calls to maps package\n\nThe mapsloop analyzer replaces loops of the form\n\n\tfor k, v := range x { m[k] = v }\n\nwith a single call to a function from the `maps` package, added in Go 1.23.\nDepending on the context, this could be `maps.Copy`, `maps.Insert`,\n`maps.Clone`, or `maps.Collect`.\n\nThe transformation to `maps.Clone` is applied conservatively, as it\npreserves the nilness of the source map, which may be a subtle change in\nbehavior if the original code did not handle a nil map in the same way.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#mapsloop",
			"Default": true
		},
		{
			"Name": "minmax",
			"Doc": "replace if/else statements with calls to min or max\n\nThe minmax analyzer simplifies conditional assignments by suggesting the use\nof the built-in `min` and `max` functions, introduced in Go 1.21. For example,\n\n\tif a \u003c b { x = a } else { x = b }\n\nis replaced by\n\n\tx = min(a, b).\n\nThis analyzer avoids making suggestions for floating-point types,\nas the behavior of `min` and `max` with NaN values can differ from\nthe original if/else statement.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#minmax",
			"Default": true
		},
		{
			"Name": "newexpr",
			"Doc": "simplify code by using go1.26's new(expr)\n\nThis analyzer finds declarations of functions of this form:\n\n\tfunc varOf(x int) *int { return \u0026x }\n\nand suggests a fix to turn them into inlinable wrappers around\ngo1.26's built-in new(expr) function:\n\n\t//go:fix inline\n\tfunc varOf(x int) *int { return new(x) }\n\n(The directive comment causes the 'inline' analyzer to suggest\nthat calls to such functions are inlined.)\n\nIn addition, this analyzer suggests a fix for each call\nto one of the functions before it is transformed, so that\n\n\tuse(varOf(123))\n\nis replaced by:\n\n\tuse(new(123))\n\nWrapper functions such as varOf are common when working with Go\nserialization packages such as for JSON or protobuf, where pointers\nare often used to express optionality.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#newexpr",
			"Default": true
		},
		{
			"Name": "nilfunc",
			"Doc": "check for useless comparisons between functions and nil\n\nA useless comparison is one like f == nil as opposed to f() == nil.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilfunc",
			"Default": true
		},
		{
			"Name": "nilness",
			"Doc": "check for redundant or impossible nil comparisons\n\nThe nilness checker inspects the control-flow graph of each function in\na package and reports nil pointer dereferences, degenerate nil\npointers, and panics with nil values. A degenerate comparison is of the form\nx==nil or x!=nil where x is statically known to be nil or non-nil. These are\noften a mistake, especially in control flow related to errors. Panics with nil\nvalues are checked because they are not detectable by\n\n\tif r := recover(); r != nil {\n\nThis check reports conditions such as:\n\n\tif f == nil { // impossible condition (f is a function)\n\t}\n\nand:\n\n\tp := \u0026v\n\t...\n\tif p != nil { // tautological condition\n\t}\n\nand:\n\n\tif p == nil {\n\t\tprint(*p) // nil dereference\n\t}\n\nand:\n\n\tif p == nil {\n\t\tpanic(p)\n\t}\n\nSometimes the control flow may be quite complex, making bugs hard\nto spot. In the example below, the err.Error expression is\nguaranteed to panic because, after the first return, err must be\nnil. The intervening loop is just a distraction.\n\n\t...\n\terr := g.Wait()\n\tif err != nil {\n\t\treturn err\n\t}\n\tpartialSuccess := false\n\tfor _, err := range errs {\n\t\tif err == nil {\n\t\t\tpartialSuccess = true\n\t\t\tbreak\n\t\t}\n\t}\n\tif partialSuccess {\n\t\treportStatus(StatusMessage{\n\t\t\tCode:   code.ERROR,\n\t\t\tDetail: err.Error(), // \"nil dereference in dynamic method call\"\n\t\t})\n\t\treturn nil\n\t}\n\n...",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/nilness",
			"Default": true
		},
		{
			"Name": "nonewvars",
			"Doc": "suggested fixes for \"no new vars on left side of :=\"\n\nThis checker provides suggested fixes for type errors of the\ntype \"no new vars on left side of :=\". For example:\n\n\tz := 1\n\tz := 2\n\nwill turn into\n\n\tz := 1\n\tz = 2",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/nonewvars",
			"Default": true
		},
		{
			"Name": "noresultvalues",
			"Doc": "suggested fixes for unexpected return values\n\nThis checker provides suggested fixes for type errors of the\ntype \"no result values expected\" or \"too many return values\".\nFor example:\n\n\tfunc z() { return nil }\n\nwill turn into\n\n\tfunc z() { return }",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/noresultvalues",
			"Default": true
		},
		{
			"Name": "omitzero",
			"Doc": "suggest replacing omitempty with omitzero for struct fields\n\nThe omitzero analyzer identifies uses of the `omitempty` JSON struct\ntag on fields that are themselves structs. For struct-typed fields,\nthe `omitempty` tag has no effect on the behavior of json.Marshal and\njson.Unmarshal. The analyzer offers two suggestions: either remove the\ntag, or replace it with `omitzero` (added in Go 1.24), which correctly\nomits the field if the struct value is zero.\n\nHowever, some other serialization packages (notably kubebuilder, see\nhttps://book.kubebuilder.io/reference/markers.html) may have their own\ninterpretation of the `json:\",omitzero\"` tag, so removing it may affect\nprogram behavior. For this reason, the omitzero modernizer will not\nmake changes in any package that contains +kubebuilder annotations.\n\nReplacing `omitempty` with `omitzero` is a change in behavior. The\noriginal code would always encode the struct field, whereas the\nmodified code will omit it if it is a zero-value.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#omitzero",
			"Default": true
		},
		{
			"Name": "plusbuild",
			"Doc": "remove obsolete //+build comments\n\nThe plusbuild analyzer suggests a fix to remove obsolete build tags\nof the form:\n\n\t//+build linux,amd64\n\nin files that also contain a Go 1.18-style tag such as:\n\n\t//go:build linux \u0026\u0026 amd64\n\n(It does not check that the old and new tags are consistent;\nthat is the job of the 'buildtag' analyzer in the vet suite.)",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#plusbuild",
			"Default": true
		},
		{
			"Name": "printf",
			"Doc": "check consistency of Printf format strings and arguments\n\nThe check applies to calls of the formatting functions such as\n[fmt.Printf] and [fmt.Sprintf], as well as any detected wrappers of\nthose functions such as [log.Printf]. It reports a variety of\nmistakes such as syntax errors in the format string and mismatches\n(of number and type) between the verbs and their arguments.\n\nSee the documentation of the fmt package for the complete set of\nformat operators and their operand types.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/printf",
			"Default": true
		},
		{
			"Name": "rangeint",
			"Doc": "replace 3-clause for loops with for-range over integers\n\nThe rangeint analyzer suggests replacing traditional for loops such\nas\n\n\tfor i := 0; i \u003c n; i++ { ... }\n\nwith the more idiomatic Go 1.22 style:\n\n\tfor i := range n { ... }\n\nThis transformation is applied only if (a) the loop variable is not\nmodified within the loop body and (b) the loop's limit expression\nis not modified within the loop, as `for range` evaluates its\noperand only once.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#rangeint",
			"Default": true
		},
		{
			"Name": "recursiveiter",
			"Doc": "check for inefficient recursive iterators\n\nThis analyzer reports when a function that returns an iterator\n(iter.Seq or iter.Seq2) calls itself as the operand of a range\nstatement, as this is inefficient.\n\nWhen implementing an iterator (e.g. iter.Seq[T]) for a recursive\ndata type such as a tree or linked list, it is tempting to\nrecursively range over the iterator for each child element.\n\nHere's an example of a naive iterator over a binary tree:\n\n\ttype tree struct {\n\t\tvalue       int\n\t\tleft, right *tree\n\t}\n\n\tfunc (t *tree) All() iter.Seq[int] {\n\t\treturn func(yield func(int) bool) {\n\t\t\tif t != nil {\n\t\t\t\tfor elem := range t.left.All() { // \"inefficient recursive iterator\"\n\t\t\t\t\tif !yield(elem) {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t\tif !yield(t.value) {\n\t\t\t\t\treturn\n\t\t\t\t}\n\t\t\t\tfor elem := range t.right.All() { // \"inefficient recursive iterator\"\n\t\t\t\t\tif !yield(elem) {\n\t\t\t\t\t\treturn\n\t\t\t\t\t}\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\nThough it correctly enumerates the elements of the tree, it hides a\nsignificant performance problem--two, in fact. Consider a balanced\ntree of N nodes. Iterating the root node will cause All to be\ncalled once on every node of the tree. This results in a chain of\nnested active range-over-func statements when yield(t.value) is\ncalled on a leaf node.\n\nThe first performance problem is that each range-over-func\nstatement must typically heap-allocate a variable, so iteration of\nthe tree allocates as many variables as there are elements in the\ntree, for a total of O(N) allocations, all unnecessary.\n\nThe second problem is that each call to yield for a leaf of the\ntree causes each of the enclosing range loops to receive a value,\nwhich they then immediately pass on to their respective yield\nfunction. This results in a chain of log(N) dynamic yield calls per\nelement, a total of O(N*log N) dynamic calls overall, when only\nO(N) are necessary.\n\nA better implementation strategy for recursive iterators is to\nfirst define the \"every\" operator for your recursive data type,\nwhere every(f) reports whether an arbitrary predicate f(x) is true\nfor every element x in the data type. For our tree, the every\nfunction would be:\n\n\tfunc (t *tree) every(f func(int) bool) bool {\n\t\treturn t == nil ||\n\t\t\tt.left.every(f) \u0026\u0026 f(t.value) \u0026\u0026 t.right.every(f)\n\t}\n\nFor example, this use of the every operator prints whether every\nelement in the tree is an even number:\n\n\teven := func(x int) bool { return x\u00261 == 0 }\n\tprintln(t.every(even))\n\nThen the iterator can be simply expressed as a trivial wrapper\naround the every operator:\n\n\tfunc (t *tree) All() iter.Seq[int] {\n\t\treturn func(yield func(int) bool) {\n\t\t\t_ = t.every(yield)\n\t\t}\n\t}\n\nIn effect, tree.All computes whether yield returns true for each\nelement, short-circuiting if it ever returns false, then discards\nthe final boolean result.\n\nThis has much better performance characteristics: it makes one\ndynamic call per element of the tree, and it doesn't heap-allocate\nanything. It is also clearer.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/recursiveiter",
			"Default": true
		},
		{
			"Name": "reflecttypefor",
			"Doc": "replace reflect.TypeOf(x) with TypeFor[T]()\n\nThis analyzer suggests fixes to replace uses of reflect.TypeOf(x) with\nreflect.TypeFor, introduced in go1.22, when the desired runtime type\nis known at compile time, for example:\n\n\treflect.TypeOf(uint32(0))        -\u003e reflect.TypeFor[uint32]()\n\treflect.TypeOf((*ast.File)(nil)) -\u003e reflect.TypeFor[*ast.File]()\n\nIt also offers a fix to simplify the constructions below, which use\nreflect.TypeOf to return the runtime type for an interface type,\n\n\treflect.TypeOf((*io.Reader)(nil)).Elem()\n\nor:\n\n\treflect.TypeOf([]io.Reader(nil)).Elem()\n\nto:\n\n\treflect.TypeFor[io.Reader]()\n\nNo fix is offered in cases when the runtime type is dynamic, such as:\n\n\tvar r io.Reader = ...\n\treflect.TypeOf(r)\n\nor when the operand has potential side effects.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#reflecttypefor",
			"Default": true
		},
		{
			"Name": "shadow",
			"Doc": "check for possible unintended shadowing of variables\n\nThis analyzer check for shadowed variables.\nA shadowed variable is a variable declared in an inner scope\nwith the same name and type as a variable in an outer scope,\nand where the outer variable is mentioned after the inner one\nis declared.\n\n(This definition can be refined; the module generates too many\nfalse positives and is not yet enabled by default.)\n\nFor example:\n\n\tfunc BadRead(f *os.File, buf []byte) error {\n\t\tvar err error\n\t\tfor {\n\t\t\tn, err := f.Read(buf) // shadows the function variable 'err'\n\t\t\tif err != nil {\n\t\t\t\tbreak // causes return of wrong value\n\t\t\t}\n\t\t\tfoo(buf)\n\t\t}\n\t\treturn err\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shadow",
			"Default": false
		},
		{
			"Name": "shift",
			"Doc": "check for shifts that equal or exceed the width of the integer",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/shift",
			"Default": true
		},
		{
			"Name": "sigchanyzer",
			"Doc": "check for unbuffered channel of os.Signal\n\nThis checker reports call expression of the form\n\n\tsignal.Notify(c \u003c-chan os.Signal, sig ...os.Signal),\n\nwhere c is an unbuffered channel, which can be at risk of missing the signal.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sigchanyzer",
			"Default": true
		},
		{
			"Name": "simplifycompositelit",
			"Doc": "check for composite literal simplifications\n\nAn array, slice, or map composite literal of the form:\n\n\t[]T{T{}, T{}}\n\nwill be simplified to:\n\n\t[]T{{}, {}}\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifycompositelit",
			"Default": true
		},
		{
			"Name": "simplifyrange",
			"Doc": "check for range statement simplifications\n\nA range of the form:\n\n\tfor x, _ = range v {...}\n\nwill be simplified to:\n\n\tfor x = range v {...}\n\nA range of the form:\n\n\tfor _ = range v {...}\n\nwill be simplified to:\n\n\tfor range v {...}\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyrange",
			"Default": true
		},
		{
			"Name": "simplifyslice",
			"Doc": "check for slice simplifications\n\nA slice expression of the form:\n\n\ts[a:len(s)]\n\nwill be simplified to:\n\n\ts[a:]\n\nThis is one of the simplifications that \"gofmt -s\" applies.\n\nThis analyzer ignores generated code.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/simplifyslice",
			"Default": true
		},
		{
			"Name": "slicescontains",
			"Doc": "replace loops with slices.Contains or slices.ContainsFunc\n\nThe slicescontains analyzer simplifies loops that check for the existence of\nan element in a slice. It replaces them with calls to `slices.Contains` or\n`slices.ContainsFunc`, which were added in Go 1.21.\n\nIf the expression for the target element has side effects, this\ntransformation will cause those effects to occur only once, not\nonce per tested slice element.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicescontains",
			"Default": true
		},
		{
			"Name": "slicesdelete",
			"Doc": "replace append-based slice deletion with slices.Delete\n\nThe slicesdelete analyzer suggests replacing the idiom\n\n\ts = append(s[:i], s[j:]...)\n\nwith the more explicit\n\n\ts = slices.Delete(s, i, j)\n\nintroduced in Go 1.21.\n\nThis analyzer is disabled by default. The `slices.Delete` function\nzeros the elements between the new length and the old length of the\nslice to prevent memory leaks, which is a subtle difference in\nbehavior compared to the append-based idiom; see https://go.dev/issue/73686.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicesdelete",
			"Default": false
		},
		{
			"Name": "slicessort",
			"Doc": "replace sort.Slice with slices.Sort for basic types\n\nThe slicessort analyzer simplifies sorting slices of basic ordered\ntypes. It replaces\n\n\tsort.Slice(s, func(i, j int) bool { return s[i] \u003c s[j] })\n\nwith the simpler `slices.Sort(s)`, which was added in Go 1.21.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#slicessort",
			"Default": true
		},
		{
			"Name": "slog",
			"Doc": "check for invalid structured logging calls\n\nThe slog checker looks for calls to functions from the log/slog\npackage that take alternating key-value pairs. It reports calls\nwhere an argument in a key position is neither a string nor a\nslog.Attr, and where a final key is missing its value.\nFor example,it would report\n\n\tslog.Warn(\"message\", 11, \"k\") // slog.Warn arg \"11\" should be a string or a slog.Attr\n\nand\n\n\tslog.Info(\"message\", \"k1\", v1, \"k2\") // call to slog.Info missing a final value",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/slog",
			"Default": true
		},
		{
			"Name": "sortslice",
			"Doc": "check the argument type of sort.Slice\n\nsort.Slice requires an argument of a slice type. Check that\nthe interface{} value passed to sort.Slice is actually a slice.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/sortslice",
			"Default": true
		},
		{
			"Name": "stditerators",
			"Doc": "use iterators instead of Len/At-style APIs\n\nThis analyzer suggests a fix to replace each loop of the form:\n\n\tfor i := 0; i \u003c x.Len(); i++ {\n\t\tuse(x.At(i))\n\t}\n\nor its \"for elem := range x.Len()\" equivalent by a range loop over an\niterator offered by the same data type:\n\n\tfor elem := range x.All() {\n\t\tuse(x.At(i)\n\t}\n\nwhere x is one of various well-known types in the standard library.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stditerators",
			"Default": true
		},
		{
			"Name": "stdmethods",
			"Doc": "check signature of methods of well-known interfaces\n\nSometimes a type may be intended to satisfy an interface but may fail to\ndo so because of a mistake in its method signature.\nFor example, the result of this WriteTo method should be (int64, error),\nnot error, to satisfy io.WriterTo:\n\n\ttype myWriterTo struct{...}\n\tfunc (myWriterTo) WriteTo(w io.Writer) error { ... }\n\nThis check ensures that each method whose name matches one of several\nwell-known interface methods from the standard library has the correct\nsignature for that interface.\n\nChecked method names include:\n\n\tFormat GobEncode GobDecode MarshalJSON MarshalXML\n\tPeek ReadByte ReadFrom ReadRune Scan Seek\n\tUnmarshalJSON UnreadByte UnreadRune WriteByte\n\tWriteTo",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdmethods",
			"Default": true
		},
		{
			"Name": "stdversion",
			"Doc": "report uses of too-new standard library symbols\n\nThe stdversion analyzer reports references to symbols in the standard\nlibrary that were introduced by a Go release higher than the one in\nforce in the referring file. (Recall that the file's Go version is\ndefined by the 'go' directive its module's go.mod file, or by a\n\"//go:build go1.X\" build tag at the top of the file.)\n\nThe analyzer does not report a diagnostic for a reference to a \"too\nnew\" field or method of a type that is itself \"too new\", as this may\nhave false positives, for example if fields or methods are accessed\nthrough a type alias that is guarded by a Go version constraint.\n",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stdversion",
			"Default": true
		},
		{
			"Name": "stringintconv",
			"Doc": "check for string(int) conversions\n\nThis checker flags conversions of the form string(x) where x is an integer\n(but not byte or rune) type. Such conversions are discouraged because they\nreturn the UTF-8 representation of the Unicode code point x, and not a decimal\nstring representation of x as one might expect. Furthermore, if x denotes an\ninvalid code point, the conversion cannot be statically rejected.\n\nFor conversions that intend on using the code point, consider replacing them\nwith string(rune(x)). Otherwise, strconv.Itoa and its equivalents return the\nstring representation of the value in the desired base.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/stringintconv",
			"Default": true
		},
		{
			"Name": "stringsbuilder",
			"Doc": "replace += with strings.Builder\n\nThis analyzer replaces repeated string += string concatenation\noperations with calls to Go 1.10's strings.Builder.\n\nFor example:\n\n\tvar s = \"[\"\n\tfor x := range seq {\n\t\ts += x\n\t\ts += \".\"\n\t}\n\ts += \"]\"\n\tuse(s)\n\nis replaced by:\n\n\tvar s strings.Builder\n\ts.WriteString(\"[\")\n\tfor x := range seq {\n\t\ts.WriteString(x)\n\t\ts.WriteString(\".\")\n\t}\n\ts.WriteString(\"]\")\n\tuse(s.String())\n\nThis avoids quadratic memory allocation and improves performance.\n\nThe analyzer requires that all references to s before the final uses\nare += operations. To avoid warning about trivial cases, at least one\nmust appear within a loop. The variable s must be a local\nvariable, not a global or parameter.\n\nAll uses of the finished string must come after the last += operation.\nEach such use will be replaced by a call to strings.Builder's String method.\n(These may appear within an intervening loop or function literal, since even\nif s.String() is called repeatedly, it does not allocate memory.)\n\nOften the addend is a call to fmt.Sprintf, as in this example:\n\n\tvar s string\n\tfor x := range seq {\n\t\ts += fmt.Sprintf(\"%v\", x)\n\t}\n\nwhich, once the suggested fix is applied, becomes:\n\n\tvar s strings.Builder\n\tfor x := range seq {\n\t\ts.WriteString(fmt.Sprintf(\"%v\", x))\n\t}\n\nThe WriteString call can be further simplified to the more efficient\nfmt.Fprintf(\u0026s, \"%v\", x), avoiding the allocation of an intermediary.\nHowever, stringsbuilder does not perform this simplification;\nit requires staticcheck analyzer QF1012. (See https://go.dev/issue/76918.)",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringbuilder",
			"Default": true
		},
		{
			"Name": "stringscut",
			"Doc": "replace strings.Index etc. with strings.Cut\n\nThis analyzer replaces certain patterns of use of [strings.Index] and string slicing by [strings.Cut], added in go1.18.\n\nFor example:\n\n\tidx := strings.Index(s, substr)\n\tif idx \u003e= 0 {\n\t    return s[:idx]\n\t}\n\nis replaced by:\n\n\tbefore, _, ok := strings.Cut(s, substr)\n\tif ok {\n\t    return before\n\t}\n\nAnd:\n\n\tidx := strings.Index(s, substr)\n\tif idx \u003e= 0 {\n\t    return\n\t}\n\nis replaced by:\n\n\tfound := strings.Contains(s, substr)\n\tif found {\n\t    return\n\t}\n\nIt also handles variants using [strings.IndexByte] instead of Index, or the bytes package instead of strings.\n\nFixes are offered only in cases in which there are no potential modifications of the idx, s, or substr expressions between their definition and use.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscut",
			"Default": true
		},
		{
			"Name": "stringscutprefix",
			"Doc": "replace HasPrefix/TrimPrefix with CutPrefix\n\nThe stringscutprefix analyzer simplifies a common pattern where code first\nchecks for a prefix with `strings.HasPrefix` and then removes it with\n`strings.TrimPrefix`. It replaces this two-step process with a single call\nto `strings.CutPrefix`, introduced in Go 1.20. The analyzer also handles\nthe equivalent functions in the `bytes` package.\n\nFor example, this input:\n\n\tif strings.HasPrefix(s, prefix) {\n\t    use(strings.TrimPrefix(s, prefix))\n\t}\n\nis fixed to:\n\n\tif after, ok := strings.CutPrefix(s, prefix); ok {\n\t    use(after)\n\t}\n\nThe analyzer also offers fixes to use CutSuffix in a similar way.\nThis input:\n\n\tif strings.HasSuffix(s, suffix) {\n\t    use(strings.TrimSuffix(s, suffix))\n\t}\n\nis fixed to:\n\n\tif before, ok := strings.CutSuffix(s, suffix); ok {\n\t    use(before)\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringscutprefix",
			"Default": true
		},
		{
			"Name": "stringsseq",
			"Doc": "replace ranging over Split/Fields with SplitSeq/FieldsSeq\n\nThe stringsseq analyzer improves the efficiency of iterating over substrings.\nIt replaces\n\n\tfor range strings.Split(...)\n\nwith the more efficient\n\n\tfor range strings.SplitSeq(...)\n\nwhich was added in Go 1.24 and avoids allocating a slice for the\nsubstrings. The analyzer also handles strings.Fields and the\nequivalent functions in the bytes package.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#stringsseq",
			"Default": true
		},
		{
			"Name": "structtag",
			"Doc": "check that struct field tags conform to reflect.StructTag.Get\n\nAlso report certain struct tags (json, xml) used with unexported fields.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/structtag",
			"Default": true
		},
		{
			"Name": "testingcontext",
			"Doc": "replace context.WithCancel with t.Context in tests\n\nThe testingcontext analyzer simplifies context management in tests. It\nreplaces the manual creation of a cancellable context,\n\n\tctx, cancel := context.WithCancel(context.Background())\n\tdefer cancel()\n\nwith a single call to t.Context(), which was added in Go 1.24.\n\nThis change is only suggested if the `cancel` function is not used\nfor any other purpose.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#testingcontext",
			"Default": true
		},
		{
			"Name": "testinggoroutine",
			"Doc": "report calls to (*testing.T).Fatal from goroutines started by a test\n\nFunctions that abruptly terminate a test, such as the Fatal, Fatalf, FailNow, and\nSkip{,f,Now} methods of *testing.T, must be called from the test goroutine itself.\nThis checker detects calls to these functions that occur within a goroutine\nstarted by the test. For example:\n\n\tfunc TestFoo(t *testing.T) {\n\t    go func() {\n\t        t.Fatal(\"oops\") // error: (*T).Fatal called from non-test goroutine\n\t    }()\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/testinggoroutine",
			"Default": true
		},
		{
			"Name": "tests",
			"Doc": "check for common mistaken usages of tests and examples\n\nThe tests checker walks Test, Benchmark, Fuzzing and Example functions checking\nmalformed names, wrong signatures and examples documenting non-existent\nidentifiers.\n\nPlease see the documentation for package testing in golang.org/pkg/testing\nfor the conventions that are enforced for Tests, Benchmarks, and Examples.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/tests",
			"Default": true
		},
		{
			"Name": "timeformat",
			"Doc": "check for calls of (time.Time).Format or time.Parse with 2006-02-01\n\nThe timeformat checker looks for time formats with the 2006-02-01 (yyyy-dd-mm)\nformat. Internationally, \"yyyy-dd-mm\" does not occur in common calendar date\nstandards, and so it is more likely that 2006-01-02 (yyyy-mm-dd) was intended.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/timeformat",
			"Default": true
		},
		{
			"Name": "unmarshal",
			"Doc": "report passing non-pointer or non-interface values to unmarshal\n\nThe unmarshal analysis reports calls to functions such as json.Unmarshal\nin which the argument type is not a pointer or an interface.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unmarshal",
			"Default": true
		},
		{
			"Name": "unreachable",
			"Doc": "check for unreachable code\n\nThe unreachable analyzer finds statements that execution can never reach\nbecause they are preceded by a return statement, a call to panic, an\ninfinite loop, or similar constructs.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unreachable",
			"Default": true
		},
		{
			"Name": "unsafefuncs",
			"Doc": "replace unsafe pointer arithmetic with function calls\n\nThe unsafefuncs analyzer simplifies pointer arithmetic expressions by\nreplacing them with calls to helper functions such as unsafe.Add,\nadded in Go 1.17.\n\nExample:\n\n\tunsafe.Pointer(uintptr(ptr) + uintptr(n))\n\nwhere ptr is an unsafe.Pointer, is replaced by:\n\n\tunsafe.Add(ptr, n)",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#unsafefuncs",
			"Default": true
		},
		{
			"Name": "unsafeptr",
			"Doc": "check for invalid conversions of uintptr to unsafe.Pointer\n\nThe unsafeptr analyzer reports likely incorrect uses of unsafe.Pointer\nto convert integers to pointers. A conversion from uintptr to\nunsafe.Pointer is invalid if it implies that there is a uintptr-typed\nword in memory that holds a pointer value, because that word will be\ninvisible to stack copying and to the garbage collector.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unsafeptr",
			"Default": true
		},
		{
			"Name": "unusedfunc",
			"Doc": "check for unused functions, methods, etc\n\nThe unusedfunc analyzer reports functions and methods that are\nnever referenced outside of their own declaration.\n\nA function is considered unused if it is unexported and not\nreferenced (except within its own declaration).\n\nA method is considered unused if it is unexported, not referenced\n(except within its own declaration), and its name does not match\nthat of any method of an interface type declared within the same\npackage.\n\nThe tool may report false positives in some situations, for\nexample:\n\n  - for a declaration of an unexported function that is referenced\n    from another package using the go:linkname mechanism, if the\n    declaration's doc comment does not also have a go:linkname\n    comment.\n\n    (Such code is in any case strongly discouraged: linkname\n    annotations, if they must be used at all, should be used on both\n    the declaration and the alias.)\n\n  - for compiler intrinsics in the \"runtime\" package that, though\n    never referenced, are known to the compiler and are called\n    indirectly by compiled object code.\n\n  - for functions called only from assembly.\n\n  - for functions called only from files whose build tags are not\n    selected in the current build configuration.\n\nSince these situations are relatively common in the low-level parts\nof the runtime, this analyzer ignores the standard library.\nSee https://go.dev/issue/71686 and https://go.dev/issue/74130 for\nfurther discussion of these limitations.\n\nThe unusedfunc algorithm is not as precise as the\ngolang.org/x/tools/cmd/deadcode tool, but it has the advantage that\nit runs within the modular analysis framework, enabling near\nreal-time feedback within gopls.\n\nThe unusedfunc analyzer also reports unused types, vars, and\nconstants. Enums--constants defined with iota--are ignored since\neven the unused values must remain present to preserve the logical\nordering.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedfunc",
			"Default": true
		},
		{
			"Name": "unusedparams",
			"Doc": "check for unused parameters of functions\n\nThe unusedparams analyzer checks functions to see if there are\nany parameters that are not being used.\n\nTo ensure soundness, it ignores:\n  - \"address-taken\" functions, that is, functions that are used as\n    a value rather than being called directly; their signatures may\n    be required to conform to a func type.\n  - exported functions or methods, since they may be address-taken\n    in another package.\n  - unexported methods whose name matches an interface method\n    declared in the same package, since the method's signature\n    may be required to conform to the interface type.\n  - functions with empty bodies, or containing just a call to panic.\n  - parameters that are unnamed, or named \"_\", the blank identifier.\n\nThe analyzer suggests a fix of replacing the parameter name by \"_\",\nbut in such cases a deeper fix can be obtained by invoking the\n\"Refactor: remove unused parameter\" code action, which will\neliminate the parameter entirely, along with all corresponding\narguments at call sites, while taking care to preserve any side\neffects in the argument expressions; see\nhttps://github.com/golang/tools/releases/tag/gopls%2Fv0.14.\n\nThis analyzer ignores generated code.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedparams",
			"Default": true
		},
		{
			"Name": "unusedresult",
			"Doc": "check for unused results of calls to some functions\n\nSome functions like fmt.Errorf return a result and have no side\neffects, so it is always a mistake to discard the result. Other\nfunctions may return an error that must not be ignored, or a cleanup\noperation that must be called. This analyzer reports calls to\nfunctions like these when the result of the call is ignored.\n\nThe set of functions may be controlled using flags.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedresult",
			"Default": true
		},
		{
			"Name": "unusedvariable",
			"Doc": "check for unused variables and suggest fixes",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/unusedvariable",
			"Default": true
		},
		{
			"Name": "unusedwrite",
			"Doc": "checks for unused writes\n\nThe analyzer reports instances of writes to struct fields and\narrays that are never read. Specifically, when a struct object\nor an array is copied, its elements are copied implicitly by\nthe compiler, and any element write to this copy does nothing\nwith the original object.\n\nFor example:\n\n\ttype T struct { x int }\n\n\tfunc f(input []T) {\n\t\tfor i, v := range input {  // v is a copy\n\t\t\tv.x = i  // unused write to field x\n\t\t}\n\t}\n\nAnother example is about non-pointer receiver:\n\n\ttype T struct { x int }\n\n\tfunc (t T) f() {  // t is a copy\n\t\tt.x = i  // unused write to field x\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/unusedwrite",
			"Default": true
		},
		{
			"Name": "waitgroup",
			"Doc": "check for misuses of sync.WaitGroup\n\nThis analyzer detects mistaken calls to the (*sync.WaitGroup).Add\nmethod from inside a new goroutine, causing Add to race with Wait:\n\n\t// WRONG\n\tvar wg sync.WaitGroup\n\tgo func() {\n\t        wg.Add(1) // \"WaitGroup.Add called from inside new goroutine\"\n\t        defer wg.Done()\n\t        ...\n\t}()\n\twg.Wait() // (may return prematurely before new goroutine starts)\n\nThe correct code calls Add before starting the goroutine:\n\n\t// RIGHT\n\tvar wg sync.WaitGroup\n\twg.Add(1)\n\tgo func() {\n\t\tdefer wg.Done()\n\t\t...\n\t}()\n\twg.Wait()",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/waitgroup",
			"Default": true
		},
		{
			"Name": "waitgroupgo",
			"Doc": "replace wg.Add(1)/go/wg.Done() with wg.Go\n\nThe waitgroupgo analyzer simplifies goroutine management with `sync.WaitGroup`.\nIt replaces the common pattern\n\n\twg.Add(1)\n\tgo func() {\n\t\tdefer wg.Done()\n\t\t...\n\t}()\n\nwith a single call to\n\n\twg.Go(func(){ ... })\n\nwhich was added in Go 1.25.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/modernize#waitgroupgo",
			"Default": true
		},
		{
			"Name": "writestring",
			"Doc": "detect inefficient string concatenation in uses of WriteString\n\nThe writestring analyzer offers to replace a call to WriteString(x + y) by\ntwo calls WriteString(x); WriteString(y). This is more efficient because it\navoids the additional memory allocation produced by string concatenation;\ninstead we just write each string into the buffer directly.\n\nIt explicitly looks for calls to certain well-known writers such as\nbytes.Buffer, strings.Builder and bufio.Writer. The analyzer will not suggest\na fix for calls to, say, (*os.File).WriteString, because for certain kinds of\nfile such as a UDP socket, it could split a single message into two.\nSimilarly it does not offer fixes when the type of the writer is unknown (as\nin calls to io.WriteString).\n\nFor example:\n\n\tfunc f(a string, b string) string {\n\t\t var s strings.Builder\n\t\t s.WriteString(a+b)\n\t\t return s.String()\n\t}\n\nwould become:\n\n\tfunc f(a string, b string) string {\n\t\tvar s strings.Builder\n\t\ts.WriteString(a)\n\t\ts.WriteString(b)\n\t\treturn s.String()\n\t}",
			"URL": "https://pkg.go.dev/golang.org/x/tools/go/analysis/passes/writestring",
			"Default": true
		},
		{
			"Name": "yield",
			"Doc": "report calls to yield where the result is ignored\n\nAfter a yield function returns false, the caller should not call\nthe yield function again; generally the iterator should return\npromptly.\n\nThis example fails to check the result of the call to yield,\ncausing this analyzer to report a diagnostic:\n\n\tyield(1) // yield may be called again (on L2) after returning false\n\tyield(2)\n\nThe corrected code is either this:\n\n\tif yield(1) { yield(2) }\n\nor simply:\n\n\t_ = yield(1) \u0026\u0026 yield(2)\n\nIt is not always a mistake to ignore the result of yield.\nFor example, this is a valid single-element iterator:\n\n\tyield(1) // ok to ignore result\n\treturn\n\nIt is only a mistake when the yield call that returned false may be\nfollowed by another call.",
			"URL": "https://pkg.go.dev/golang.org/x/tools/gopls/internal/analysis/yield",
			"Default": true
		}
	],
	"Hints": [
		{
			"Name": "assignVariableTypes",
			"Doc": "`\"assignVariableTypes\"` controls inlay hints for variable types in assign statements:\n```go\n\ti/* int*/, j/* int*/ := 0, len(r)-1\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "compositeLiteralFields",
			"Doc": "`\"compositeLiteralFields\"` inlay hints for composite literal field names:\n```go\n\t{/*in: */\"Hello, world\", /*want: */\"dlrow ,olleH\"}\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "compositeLiteralTypes",
			"Doc": "`\"compositeLiteralTypes\"` controls inlay hints for composite literal types:\n```go\n\tfor _, c := range []struct {\n\t\tin, want string\n\t}{\n\t\t/*struct{ in string; want string }*/{\"Hello, world\", \"dlrow ,olleH\"},\n\t}\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "constantValues",
			"Doc": "`\"constantValues\"` controls inlay hints for constant values:\n```go\n\tconst (\n\t\tKindNone   Kind = iota/* = 0*/\n\t\tKindPrint/*  = 1*/\n\t\tKindPrintf/* = 2*/\n\t\tKindErrorf/* = 3*/\n\t)\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "functionTypeParameters",
			"Doc": "`\"functionTypeParameters\"` inlay hints for implicit type parameters on generic functions:\n```go\n\tmyFoo/*[int, string]*/(1, \"hello\")\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "ignoredError",
			"Doc": "`\"ignoredError\"` inlay hints for implicitly discarded errors:\n```go\n\tf.Close() // ignore error\n```\nThis check inserts an `// ignore error` hint following any\nstatement that is a function call whose error result is\nimplicitly ignored.\n\nTo suppress the hint, write an actual comment containing\n\"ignore error\" following the call statement, or explicitly\nassign the result to a blank variable. A handful of common\nfunctions such as `fmt.Println` are excluded from the\ncheck.\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "parameterNames",
			"Doc": "`\"parameterNames\"` controls inlay hints for parameter names:\n```go\n\tparseInt(/* str: */ \"123\", /* radix: */ 8)\n```\n",
			"Default": false,
			"Status": ""
		},
		{
			"Name": "rangeVariableTypes",
			"Doc": "`\"rangeVariableTypes\"` controls inlay hints for variable types in range statements:\n```go\n\tfor k/* int*/, v/* string*/ := range []string{} {\n\t\tfmt.Println(k, v)\n\t}\n```\n",
			"Default": false,
			"Status": ""
		}
	]
}

================================================
FILE: gopls/internal/doc/generate/generate.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The generate command updates the following files of documentation:
//
//	gopls/doc/settings.md   -- from linking gopls/internal/settings.DefaultOptions
//	gopls/doc/analyzers.md  -- from linking gopls/internal/settings.DefaultAnalyzers
//	gopls/doc/inlayHints.md -- from loading gopls/internal/settings.InlayHint
//	gopls/internal/doc/api.json -- all of the above in a single value, for 'gopls api-json'
//
// Run it with this command:
//
//	$ cd gopls/internal/doc/generate && go generate
package main

import (
	"bytes"
	"encoding/json"
	"errors"
	"fmt"
	"go/ast"
	"go/doc/comment"
	"go/token"
	"go/types"
	"maps"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"regexp"
	"slices"
	"sort"
	"strconv"
	"strings"
	"time"
	"unicode"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/doc"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
)

func main() {
	if _, err := doMain(true); err != nil {
		fmt.Fprintf(os.Stderr, "Generation failed: %v\n", err)
		os.Exit(1)
	}
}

// doMain regenerates the output files. On success:
// - if write, it updates them;
// - if !write, it reports whether they would change.
func doMain(write bool) (bool, error) {
	api, err := loadAPI()
	if err != nil {
		return false, err
	}

	goplsDir, err := pkgDir("golang.org/x/tools/gopls")
	if err != nil {
		return false, err
	}

	// TODO(adonovan): consider using HTML, not Markdown, for the
	// generated reference documents. It's not more difficult, the
	// layout is easier to read, and we can use go/doc-comment
	// rendering logic.

	for _, f := range []struct {
		name    string // relative to gopls
		rewrite rewriter
	}{
		{"internal/doc/api.json", rewriteAPI},
		{"doc/settings.md", rewriteSettings},
		{"doc/codelenses.md", rewriteCodeLenses},
		{"doc/analyzers.md", rewriteAnalyzers},
		{"doc/inlayHints.md", rewriteInlayHints},
	} {
		file := filepath.Join(goplsDir, f.name)
		old, err := os.ReadFile(file)
		if err != nil {
			return false, err
		}

		new, err := f.rewrite(old, api)
		if err != nil {
			return false, fmt.Errorf("rewriting %q: %v", file, err)
		}

		if write {
			if err := os.WriteFile(file, new, 0); err != nil {
				return false, err
			}
		} else if !bytes.Equal(old, new) {
			return false, nil // files would change
		}
	}
	return true, nil
}

// A rewriter is a function that transforms the content of a file.
type rewriter = func([]byte, *doc.API) ([]byte, error)

// pkgDir returns the directory corresponding to the import path pkgPath.
func pkgDir(pkgPath string) (string, error) {
	cmd := exec.Command("go", "list", "-f", "{{.Dir}}", pkgPath)
	out, err := cmd.Output()
	if err != nil {
		if ee, _ := err.(*exec.ExitError); ee != nil && len(ee.Stderr) > 0 {
			return "", fmt.Errorf("%v: %w\n%s", cmd, err, ee.Stderr)
		}
		return "", fmt.Errorf("%v: %w", cmd, err)
	}
	return strings.TrimSpace(string(out)), nil
}

// loadAPI computes the JSON-encodable value that describes gopls'
// interfaces, by a combination of static and dynamic analysis.
func loadAPI() (*doc.API, error) {
	pkgs, err := packages.Load(
		&packages.Config{
			Mode: packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedDeps,
		},
		"golang.org/x/tools/gopls/internal/settings",
	)
	if err != nil {
		return nil, err
	}
	settingsPkg := pkgs[0]

	defaults := settings.DefaultOptions()
	api := &doc.API{
		Options:   map[string][]*doc.Option{},
		Analyzers: loadAnalyzers(settings.AllAnalyzers, defaults),
	}

	api.Lenses, err = loadLenses(settingsPkg, defaults.Codelenses)
	if err != nil {
		return nil, err
	}
	api.Hints, err = loadHints(settingsPkg)
	if err != nil {
		return nil, err
	}

	for _, category := range []reflect.Value{
		reflect.ValueOf(defaults.UserOptions),
	} {
		// Find the type information and ast.File corresponding to the category.
		optsType := settingsPkg.Types.Scope().Lookup(category.Type().Name())
		if optsType == nil {
			return nil, fmt.Errorf("could not find %v in scope %v", category.Type().Name(), settingsPkg.Types.Scope())
		}
		opts, err := loadOptions(category, optsType, settingsPkg, "")
		if err != nil {
			return nil, err
		}

		// Edge case for "analyses": populate its enum keys from
		// the analyzer list, since its map keys are strings, not enums.
		// Also, set its EnumKeys.ValueType for historical reasons.
		for _, opt := range opts {
			if opt.Name == "analyses" {
				opt.EnumKeys.ValueType = "bool"
				for _, a := range api.Analyzers {
					opt.EnumKeys.Keys = append(opt.EnumKeys.Keys, doc.EnumKey{
						Name:    fmt.Sprintf("%q", a.Name),
						Doc:     a.Doc,
						Default: strconv.FormatBool(a.Default),
					})
				}
			}
		}

		catName := strings.TrimSuffix(category.Type().Name(), "Options")
		api.Options[catName] = opts
	}
	return api, nil
}

// loadOptions computes a single category of settings by a combination
// of static analysis and reflection over gopls internal types.
func loadOptions(category reflect.Value, optsType types.Object, pkg *packages.Package, hierarchy string) ([]*doc.Option, error) {
	file, err := fileForPos(pkg, optsType.Pos())
	if err != nil {
		return nil, err
	}

	enums, err := loadEnums(pkg) // TODO(adonovan): do this only once at toplevel.
	if err != nil {
		return nil, err
	}

	var opts []*doc.Option
	optsStruct := optsType.Type().Underlying().(*types.Struct)
	for typesField := range optsStruct.Fields() {
		// The types field gives us the type.

		// If the field name ends with "Options", assume it is a struct with
		// additional options and process it recursively.
		if h, ok := strings.CutSuffix(typesField.Name(), "Options"); ok {
			// Keep track of the parent structs.
			if hierarchy != "" {
				h = hierarchy + "." + h
			}
			options, err := loadOptions(category, typesField, pkg, strings.ToLower(h))
			if err != nil {
				return nil, err
			}
			opts = append(opts, options...)
			continue
		}
		path, _ := goastutil.PathEnclosingInterval(file, typesField.Pos(), typesField.Pos())
		if len(path) < 2 {
			return nil, fmt.Errorf("could not find AST node for field %v", typesField)
		}

		// The AST field gives us the doc.
		astField, ok := path[1].(*ast.Field)
		if !ok {
			return nil, fmt.Errorf("unexpected AST path %v", path)
		}
		description, deprecation := astField.Doc.Text(), astutil.Deprecation(astField.Doc)

		// The reflect field gives us the default value.
		reflectField := category.FieldByName(typesField.Name())
		if !reflectField.IsValid() {
			return nil, fmt.Errorf("could not find reflect field for %v", typesField.Name())
		}

		def, err := formatDefault(reflectField)
		if err != nil {
			return nil, err
		}

		// Derive the doc-and-api.json type from the Go field type.
		//
		// In principle, we should use JSON nomenclature here
		// (number, array, object, etc; see #68057), but in
		// practice we use the Go type string ([]T, map[K]V,
		// etc) with only one tweak: enumeration types are
		// replaced by "enum", including when they appear as
		// map keys.
		//
		// Notable edge cases:
		// - any (e.g. in linksInHover) is really a sum of false | true | "internal".
		// - time.Duration is really a string with a particular syntax.
		typ := typesField.Type().String()
		if _, ok := enums[typesField.Type()]; ok {
			typ = "enum"
		}
		name := lowerFirst(typesField.Name())

		// enum-keyed maps
		var enumKeys doc.EnumKeys
		if m, ok := typesField.Type().Underlying().(*types.Map); ok {
			if values, ok := enums[m.Key()]; ok {
				// Update type name: "map[CodeLensSource]T" -> "map[enum]T"
				// hack: assumes key substring is unique!
				typ = strings.Replace(typ, m.Key().String(), "enum", 1)

				enumKeys.ValueType = m.Elem().String() // e.g. bool

				// For map[enum]T fields, gather the set of valid
				// EnumKeys (from type information). If T=bool, also
				// record the default value (from reflection).
				keys, err := collectEnumKeys(m, reflectField, values)
				if err != nil {
					return nil, err
				}
				enumKeys.Keys = keys
			}
		}

		// Get the status of the field by checking its struct tags.
		reflectStructField, ok := category.Type().FieldByName(typesField.Name())
		if !ok {
			return nil, fmt.Errorf("no struct field for %s", typesField.Name())
		}
		status := reflectStructField.Tag.Get("status")

		opts = append(opts, &doc.Option{
			Name:               name,
			Type:               typ,
			Doc:                lowerFirst(description),
			Default:            def,
			EnumKeys:           enumKeys,
			EnumValues:         enums[typesField.Type()],
			Status:             status,
			Hierarchy:          hierarchy,
			DeprecationMessage: lowerFirst(strings.TrimPrefix(deprecation, "Deprecated: ")),
		})
	}
	return opts, nil
}

// loadEnums returns a description of gopls' settings enum types based on static analysis.
func loadEnums(pkg *packages.Package) (map[types.Type][]doc.EnumValue, error) {
	enums := make(map[types.Type][]doc.EnumValue)
	for _, name := range pkg.Types.Scope().Names() {
		obj := pkg.Types.Scope().Lookup(name)
		cnst, ok := obj.(*types.Const)
		if !ok {
			continue
		}
		f, err := fileForPos(pkg, cnst.Pos())
		if err != nil {
			return nil, fmt.Errorf("finding file for %q: %v", cnst.Name(), err)
		}
		path, _ := goastutil.PathEnclosingInterval(f, cnst.Pos(), cnst.Pos())
		spec := path[1].(*ast.ValueSpec)
		value := cnst.Val().ExactString()
		docstring := valueDoc(cnst.Name(), value, spec.Doc.Text())
		var status string
		for _, d := range astutil.Directives(spec.Doc) {
			if d.Tool == "gopls" && d.Name == "status" {
				status = d.Args
				break
			}
		}
		v := doc.EnumValue{
			Value:  value,
			Doc:    docstring,
			Status: status,
		}
		enums[obj.Type()] = append(enums[obj.Type()], v)
	}

	// linksInHover is a one-off edge case (true | false | "gopls")
	// that doesn't warrant a general solution (e.g. struct tag).
	enums[pkg.Types.Scope().Lookup("LinksInHoverEnum").Type()] = []doc.EnumValue{
		{Value: "false", Doc: "false: do not show links"},
		{Value: "true", Doc: "true: show links to the `linkTarget` domain"},
		{Value: `"gopls"`, Doc: "`\"gopls\"`: show links to gopls' internal documentation viewer"},
	}

	return enums, nil
}

func collectEnumKeys(m *types.Map, reflectField reflect.Value, enumValues []doc.EnumValue) ([]doc.EnumKey, error) {
	// We can get default values for enum -> bool maps.
	var isEnumBoolMap bool
	if basic, ok := m.Elem().Underlying().(*types.Basic); ok && basic.Kind() == types.Bool {
		isEnumBoolMap = true
	}
	var keys []doc.EnumKey
	for _, v := range enumValues {
		var def string
		if isEnumBoolMap {
			var err error
			def, err = formatDefaultFromEnumBoolMap(reflectField, v.Value)
			if err != nil {
				return nil, err
			}
		}
		keys = append(keys, doc.EnumKey{
			Name:    v.Value,
			Doc:     v.Doc,
			Status:  v.Status,
			Default: def,
		})
	}
	return keys, nil
}

func formatDefaultFromEnumBoolMap(reflectMap reflect.Value, enumKey string) (string, error) {
	if reflectMap.Kind() != reflect.Map {
		return "", nil
	}
	name := enumKey
	if unquoted, err := strconv.Unquote(name); err == nil {
		name = unquoted
	}
	for _, e := range reflectMap.MapKeys() {
		if e.String() == name {
			value := reflectMap.MapIndex(e)
			if value.Type().Kind() == reflect.Bool {
				return formatDefault(value)
			}
		}
	}
	// Assume that if the value isn't mentioned in the map, it defaults to
	// the default value, false.
	return formatDefault(reflect.ValueOf(false))
}

// formatDefault formats the default value into a JSON-like string.
// VS Code exposes settings as JSON, so showing them as JSON is reasonable.
// TODO(rstambler): Reconsider this approach, as the VS Code Go generator now
// marshals to JSON.
func formatDefault(reflectField reflect.Value) (string, error) {
	def := reflectField.Interface()

	// Durations marshal as nanoseconds, but we want the stringy versions,
	// e.g. "100ms".
	if t, ok := def.(time.Duration); ok {
		def = t.String()
	}
	defBytes, err := json.Marshal(def)
	if err != nil {
		return "", err
	}

	// Nil values format as "null" so print them as hardcoded empty values.
	switch reflectField.Type().Kind() {
	case reflect.Map:
		if reflectField.IsNil() {
			defBytes = []byte("{}")
		}
	case reflect.Slice:
		if reflectField.IsNil() {
			defBytes = []byte("[]")
		}
	}
	return string(defBytes), err
}

// valueDoc transforms a docstring documenting a constant identifier to a
// docstring documenting its value.
//
// If doc is of the form "Foo is a bar", it returns '`"fooValue"` is a bar'. If
// doc is non-standard ("this value is a bar"), it returns '`"fooValue"`: this
// value is a bar'.
func valueDoc(name, value, doc string) string {
	if doc == "" {
		return ""
	}
	if strings.HasPrefix(doc, name) {
		// docstring in standard form. Replace the subject with value.
		return fmt.Sprintf("`%s`%s", value, doc[len(name):])
	}
	return fmt.Sprintf("`%s`: %s", value, doc)
}

// loadLenses combines the syntactic comments from the settings
// package with the default values from settings.DefaultOptions(), and
// returns a list of Code Lens descriptors.
func loadLenses(settingsPkg *packages.Package, defaults map[settings.CodeLensSource]bool) ([]*doc.Lens, error) {
	// Find the CodeLensSource enums among the files of the protocol package.
	// Map each enum value to its doc comment.
	enumDoc := make(map[string]string)
	enumStatus := make(map[string]string)
	for _, f := range settingsPkg.Syntax {
		for _, decl := range f.Decls {
			if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.CONST {
				for _, spec := range decl.Specs {
					spec := spec.(*ast.ValueSpec)
					posn := safetoken.StartPosition(settingsPkg.Fset, spec.Pos())
					if id, ok := spec.Type.(*ast.Ident); ok && id.Name == "CodeLensSource" {
						if len(spec.Names) != 1 || len(spec.Values) != 1 {
							return nil, fmt.Errorf("%s: declare one CodeLensSource per line", posn)
						}
						lit, ok := spec.Values[0].(*ast.BasicLit)
						if !ok || lit.Kind != token.STRING {
							return nil, fmt.Errorf("%s: CodeLensSource value is not a string literal", posn)
						}
						value, _ := strconv.Unquote(lit.Value) // ignore error: AST is well-formed
						if spec.Doc == nil {
							return nil, fmt.Errorf("%s: %s lacks doc comment", posn, spec.Names[0].Name)
						}
						enumDoc[value] = spec.Doc.Text()
						for _, d := range astutil.Directives(spec.Doc) {
							if d.Tool == "gopls" && d.Name == "status" {
								enumStatus[value] = d.Args
								break
							}
						}
					}
				}
			}
		}
	}
	if len(enumDoc) == 0 {
		return nil, fmt.Errorf("failed to extract any CodeLensSource declarations")
	}

	// Build list of Lens descriptors.
	var lenses []*doc.Lens
	addAll := func(sources map[settings.CodeLensSource]cache.CodeLensSourceFunc, fileType string) error {
		for _, source := range slices.Sorted(maps.Keys(sources)) {
			docText, ok := enumDoc[string(source)]
			if !ok {
				return fmt.Errorf("missing CodeLensSource declaration for %s", source)
			}
			title, docText, _ := strings.Cut(docText, "\n") // first line is title
			lenses = append(lenses, &doc.Lens{
				FileType: fileType,
				Lens:     string(source),
				Title:    title,
				Doc:      docText,
				Default:  defaults[source],
				Status:   enumStatus[string(source)],
			})
		}
		return nil
	}
	err := errors.Join(
		addAll(golang.CodeLensSources(), "Go"),
		addAll(mod.CodeLensSources(), "go.mod"))
	return lenses, err
}

func loadAnalyzers(analyzers []*settings.Analyzer, defaults *settings.Options) []*doc.Analyzer {
	slices.SortFunc(analyzers, func(x, y *settings.Analyzer) int {
		return strings.Compare(x.Analyzer().Name, y.Analyzer().Name)
	})
	var json []*doc.Analyzer
	for _, a := range analyzers {
		json = append(json, &doc.Analyzer{
			Name:    a.Analyzer().Name,
			Doc:     a.Analyzer().Doc,
			URL:     a.Analyzer().URL,
			Default: a.Enabled(defaults),
		})
	}
	return json
}

// loadHints derives and returns the inlay hints metadata from the settings.InlayHint type.
func loadHints(settingsPkg *packages.Package) ([]*doc.Hint, error) {
	enums, err := loadEnums(settingsPkg) // TODO(adonovan): call loadEnums exactly once
	if err != nil {
		return nil, err
	}
	inlayHint := settingsPkg.Types.Scope().Lookup("InlayHint").Type()
	var hints []*doc.Hint
	for _, enumVal := range enums[inlayHint] {
		name, _ := strconv.Unquote(enumVal.Value)
		hints = append(hints, &doc.Hint{
			Name:   name,
			Doc:    enumVal.Doc,
			Status: enumVal.Status,
		})
	}
	return hints, nil
}

func lowerFirst(x string) string {
	if x == "" {
		return x
	}
	return strings.ToLower(x[:1]) + x[1:]
}

func fileForPos(pkg *packages.Package, pos token.Pos) (*ast.File, error) {
	fset := pkg.Fset
	for _, f := range pkg.Syntax {
		if safetoken.StartPosition(fset, f.FileStart).Filename == safetoken.StartPosition(fset, pos).Filename {
			return f, nil
		}
	}
	return nil, fmt.Errorf("no file for pos %v", pos)
}

func rewriteAPI(_ []byte, api *doc.API) ([]byte, error) {
	return json.MarshalIndent(api, "", "\t")
}

type optionsGroup struct {
	title   string // dotted path (e.g. "ui.documentation")
	final   string // final segment of title (e.g. "documentation")
	level   int
	options []*doc.Option
}

func rewriteSettings(prevContent []byte, api *doc.API) ([]byte, error) {
	content := prevContent
	for category, opts := range api.Options {
		groups := collectGroups(opts)

		var buf bytes.Buffer

		// First, print a table of contents (ToC).
		fmt.Fprintln(&buf)
		for _, h := range groups {
			title := h.final
			if title != "" {
				fmt.Fprintf(&buf, "%s* [%s](#%s)\n",
					strings.Repeat("  ", h.level),
					capitalize(title),
					strings.ToLower(title))
			}
		}

		// Section titles are h2, options are h3.
		// This is independent of the option hierarchy.
		// (Nested options should not be smaller!)
		fmt.Fprintln(&buf)
		for _, h := range groups {
			title := h.final
			if title != "" {
				// Emit HTML anchor as GitHub markdown doesn't support
				// "# Heading {#anchor}" syntax.
				fmt.Fprintf(&buf, "<a id='%s'></a>\n", strings.ToLower(title))

				fmt.Fprintf(&buf, "## %s\n\n", capitalize(title))
			}
			for _, opt := range h.options {
				// Emit HTML anchor as GitHub markdown doesn't support
				// "# Heading {#anchor}" syntax.
				//
				// (Each option name is the camelCased name of a field of
				// settings.UserOptions or one of its FooOptions subfields.)
				fmt.Fprintf(&buf, "<a id='%s'></a>\n", opt.Name)

				// heading
				//
				// We do not display the undocumented dotted-path alias
				// (h.title + "." + opt.Name) used by VS Code only.
				fmt.Fprintf(&buf, "### `%s %s`\n\n", opt.Name, opt.Type)

				// status
				writeStatus(&buf, opt.Status)

				// doc comment
				buf.WriteString(opt.Doc)

				// enums
				write := func(name, doc string) {
					if doc != "" {
						unbroken := parBreakRE.ReplaceAllString(doc, "\\\n")
						fmt.Fprintf(&buf, "* %s\n", strings.TrimSpace(unbroken))
					} else {
						fmt.Fprintf(&buf, "* `%s`\n", name)
					}
				}
				if len(opt.EnumValues) > 0 && opt.Type == "enum" {
					// enum as top-level type constructor
					buf.WriteString("\nMust be one of:\n\n")
					for _, val := range opt.EnumValues {
						write(val.Value, val.Doc)
					}
				} else if len(opt.EnumKeys.Keys) > 0 && shouldShowEnumKeysInSettings(opt.Name) {
					// enum as map key (currently just "annotations")
					buf.WriteString("\nEach enum must be one of:\n\n")
					for _, val := range opt.EnumKeys.Keys {
						write(val.Name, val.Doc)
					}
				}

				// default value
				fmt.Fprintf(&buf, "\nDefault: `%v`.\n\n", opt.Default)
			}
		}
		newContent, err := replaceSection(content, category, buf.Bytes())
		if err != nil {
			return nil, err
		}
		content = newContent
	}
	return content, nil
}

// writeStatus emits a Markdown paragraph to buf about the status of a feature,
// if nonempty.
func writeStatus(buf *bytes.Buffer, status string) {
	switch status {
	case "":
	case "advanced":
		fmt.Fprint(buf, "**This is an advanced setting and should not be configured by most `gopls` users.**\n\n")
	case "debug":
		fmt.Fprint(buf, "**This setting is for debugging purposes only.**\n\n")
	case "experimental":
		fmt.Fprint(buf, "**This setting is experimental and may be deleted.**\n\n")
	default:
		fmt.Fprintf(buf, "**Status: %s.**\n\n", status)
	}
}

var parBreakRE = regexp.MustCompile("\n{2,}")

func shouldShowEnumKeysInSettings(name string) bool {
	// These fields have too many possible options,
	// or too voluminous documentation, to render as enums.
	// Instead they each get their own page in the manual.
	return !(name == "analyses" || name == "codelenses" || name == "hints")
}

func collectGroups(opts []*doc.Option) []optionsGroup {
	optsByHierarchy := map[string][]*doc.Option{}
	for _, opt := range opts {
		optsByHierarchy[opt.Hierarchy] = append(optsByHierarchy[opt.Hierarchy], opt)
	}

	// As a hack, assume that uncategorized items are less important to
	// users and force the empty string to the end of the list.
	var containsEmpty bool
	var sorted []string
	for h := range optsByHierarchy {
		if h == "" {
			containsEmpty = true
			continue
		}
		sorted = append(sorted, h)
	}
	sort.Strings(sorted)
	if containsEmpty {
		sorted = append(sorted, "")
	}
	var groups []optionsGroup
	baseLevel := 0
	for _, h := range sorted {
		split := strings.SplitAfter(h, ".")
		last := split[len(split)-1]
		// Hack to capitalize all of UI.
		if last == "ui" {
			last = "UI"
		}
		// A hierarchy may look like "ui.formatting". If "ui" has no
		// options of its own, it may not be added to the map, but it
		// still needs a heading.
		components := strings.Split(h, ".")
		for i := 1; i < len(components); i++ {
			parent := strings.Join(components[0:i], ".")
			if _, ok := optsByHierarchy[parent]; !ok {
				groups = append(groups, optionsGroup{
					title: parent,
					final: last,
					level: baseLevel + i,
				})
			}
		}
		groups = append(groups, optionsGroup{
			title:   h,
			final:   last,
			level:   baseLevel + strings.Count(h, "."),
			options: optsByHierarchy[h],
		})
	}
	return groups
}

func capitalize(s string) string {
	return string(unicode.ToUpper(rune(s[0]))) + s[1:]
}

func rewriteCodeLenses(prevContent []byte, api *doc.API) ([]byte, error) {
	var buf bytes.Buffer
	for _, lens := range api.Lenses {
		fmt.Fprintf(&buf, "## `%s`: %s\n\n", lens.Lens, lens.Title)
		writeStatus(&buf, lens.Status)
		fmt.Fprintf(&buf, "%s\n\n", lens.Doc)
		fmt.Fprintf(&buf, "Default: %v\n\n", onOff(lens.Default))
		fmt.Fprintf(&buf, "File type: %s\n\n", lens.FileType)
	}
	return replaceSection(prevContent, "Lenses", buf.Bytes())
}

func rewriteAnalyzers(prevContent []byte, api *doc.API) ([]byte, error) {
	var buf bytes.Buffer
	for _, analyzer := range api.Analyzers {
		fmt.Fprintf(&buf, "<a id='%s'></a>\n", analyzer.Name)
		title, doc, _ := strings.Cut(analyzer.Doc, "\n")
		title = strings.TrimPrefix(title, analyzer.Name+": ")
		fmt.Fprintf(&buf, "## `%s`: %s\n\n", analyzer.Name, title)

		// Convert Analyzer.Doc from go/doc/comment form to Markdown.
		// Headings in doc comments are converted to ### (HeadingLevel=3).
		//
		// Some Analyzers (e.g. go/analysis/passes/inline) use ## to indicate subheadings
		// Although this is valid Markdown, it is not valid go/doc/comment,
		// nor is it rendered as a subheading by pkg.go.dev or gopls's doc viewer.
		// Perhaps it will be supported in future; see
		// https://github.com/golang/go/issues/51082#issuecomment-1033116430 et seq.
		//
		// In the meantime, the go/doc/comment processing will escape them so
		// that the ## appears literally in analyzers.md just as it does in
		// the two viewers mentioned above. The meaning is clear enough.
		doctree := new(comment.Parser).Parse(doc)
		buf.Write((&comment.Printer{HeadingLevel: 3}).Markdown(doctree))
		buf.WriteString("\n\n")

		fmt.Fprintf(&buf, "Default: %s.", onOff(analyzer.Default))
		if !analyzer.Default {
			fmt.Fprintf(&buf, " Enable by setting `\"analyses\": {\"%s\": true}`.", analyzer.Name)
		}
		fmt.Fprintf(&buf, "\n\n")
		if analyzer.URL != "" {
			// TODO(adonovan): currently the URL provides the same information
			// as 'doc' above, though that may change due to
			// https://github.com/golang/go/issues/61315#issuecomment-1841350181.
			// In that case, update this to something like "Complete documentation".
			fmt.Fprintf(&buf, "Package documentation: [%s](%s)\n\n",
				analyzer.Name, analyzer.URL)
		}

	}
	return replaceSection(prevContent, "Analyzers", buf.Bytes())
}

func rewriteInlayHints(prevContent []byte, api *doc.API) ([]byte, error) {
	var buf bytes.Buffer
	for _, hint := range api.Hints {
		fmt.Fprintf(&buf, "## **%v**\n\n", hint.Name)
		fmt.Fprintf(&buf, "%s\n\n", hint.Doc)
		switch hint.Default {
		case true:
			fmt.Fprintf(&buf, "**Enabled by default.**\n\n")
		case false:
			fmt.Fprintf(&buf, "**Disabled by default. Enable it by setting `\"hints\": {\"%s\": true}`.**\n\n", hint.Name)
		}
	}
	return replaceSection(prevContent, "Hints", buf.Bytes())
}

// replaceSection replaces the portion of a file delimited by comments of the form:
//
//	<!-- BEGIN sectionName -->
//	<!-- END section Name -->
func replaceSection(content []byte, sectionName string, replacement []byte) ([]byte, error) {
	re := regexp.MustCompile(fmt.Sprintf(`(?s)<!-- BEGIN %v.* -->\n(.*?)<!-- END %v.* -->`, sectionName, sectionName))
	idx := re.FindSubmatchIndex(content)
	if idx == nil {
		return nil, fmt.Errorf("could not find section %q", sectionName)
	}
	result := slices.Clone(content[:idx[2]])
	result = append(result, replacement...)
	result = append(result, content[idx[3]:]...)
	return result, nil
}

type onOff bool

func (o onOff) String() string {
	if o {
		return "on"
	} else {
		return "off"
	}
}


================================================
FILE: gopls/internal/doc/generate/generate_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func TestGenerated(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.NeedsLocalXTools(t)

	ok, err := doMain(false)
	if err != nil {
		t.Fatal(err)
	}
	if !ok {
		t.Error("documentation needs updating. Run: cd gopls && go generate ./...")
	}
}


================================================
FILE: gopls/internal/file/file.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The file package defines types used for working with LSP files.
package file

import (
	"context"
	"fmt"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
)

// An Identity identifies the name and contents of a file.
//
// TODO(rfindley): Identity may not carry its weight. Consider instead just
// exposing Handle.Hash, and using an ad-hoc key type where necessary.
// Or perhaps if mod/work parsing is moved outside of the memoize cache,
// a notion of Identity simply isn't needed.
type Identity struct {
	URI  protocol.DocumentURI
	Hash Hash // digest of file contents
}

func (id Identity) String() string {
	return fmt.Sprintf("%s%s", id.URI, id.Hash)
}

// A FileHandle represents the URI, content, hash, and optional
// version of a file tracked by the LSP session.
//
// File content may be provided by the file system (for Saved files)
// or from an overlay, for open files with unsaved edits.
// A FileHandle may record an attempt to read a non-existent file,
// in which case Content returns an error.
type Handle interface {
	// URI is the URI for this file handle.
	URI() protocol.DocumentURI
	// Identity returns an Identity for the file, even if there was an error
	// reading it.
	Identity() Identity
	// SameContentsOnDisk reports whether the file has the same content on disk:
	// it is false for files open on an editor with unsaved edits.
	SameContentsOnDisk() bool
	// Version returns the file version, as defined by the LSP client.
	// For on-disk file handles, Version returns 0.
	Version() int32
	// Content returns the contents of a file.
	// If the file is not available, returns a nil slice and an error.
	Content() ([]byte, error)
	// ModTime reports the modification time of a file.
	// If the file is not available, returns the zero time and an error.
	ModTime() (time.Time, error)
	// String returns the file's path.
	String() string
}

// A Source maps URIs to Handles.
type Source interface {
	// ReadFile returns the Handle for a given URI, either by reading the content
	// of the file or by obtaining it from a cache.
	//
	// Invariant: ReadFile must only return an error in the case of context
	// cancellation. If ctx.Err() is nil, the resulting error must also be nil.
	ReadFile(ctx context.Context, uri protocol.DocumentURI) (Handle, error)
}


================================================
FILE: gopls/internal/file/hash.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package file

import (
	"crypto/sha256"
	"fmt"
)

// A Hash is a cryptographic digest of the contents of a file.
// (Although at 32B it is larger than a 16B string header, it is smaller
// and has better locality than the string header + 64B of hex digits.)
type Hash [sha256.Size]byte

// HashOf returns the hash of some data.
func HashOf(data []byte) Hash {
	return Hash(sha256.Sum256(data))
}

// String returns the digest as a string of hex digits.
func (h Hash) String() string {
	return fmt.Sprintf("%64x", [sha256.Size]byte(h))
}

// XORWith updates *h to *h XOR h2.
func (h *Hash) XORWith(h2 Hash) {
	// Small enough that we don't need crypto/subtle.XORBytes.
	for i := range h {
		h[i] ^= h2[i]
	}
}


================================================
FILE: gopls/internal/file/kind.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package file

import (
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
)

// Kind describes the kind of the file in question.
// It can be one of Go,mod, Sum, or Tmpl.
type Kind int

const (
	// UnknownKind is a file type we don't know about.
	UnknownKind = Kind(iota)

	// Go is a Go source file.
	Go
	// Mod is a go.mod file.
	Mod
	// Sum is a go.sum file.
	Sum
	// Tmpl is a template file.
	Tmpl
	// Work is a go.work file.
	Work
	// Asm is a Go assembly (.s) file.
	Asm
)

func (k Kind) String() string {
	switch k {
	case Go:
		return "go"
	case Mod:
		return "go.mod"
	case Sum:
		return "go.sum"
	case Tmpl:
		return "tmpl"
	case Work:
		return "go.work"
	case Asm:
		return "Go assembly"
	default:
		return fmt.Sprintf("internal error: unknown file kind %d", k)
	}
}

// KindForLang returns the gopls file [Kind] associated with the given LSP
// LanguageKind string from the LanguageID field of [protocol.TextDocumentItem],
// or UnknownKind if the language is not one recognized by gopls.
func KindForLang(langID protocol.LanguageKind) Kind {
	switch langID {
	case "go":
		return Go
	case "go.mod":
		return Mod
	case "go.sum":
		return Sum
	case "tmpl", "gotmpl":
		return Tmpl
	case "go.work":
		return Work
	case "go.s":
		return Asm
	default:
		return UnknownKind
	}
}


================================================
FILE: gopls/internal/file/modification.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package file

import "golang.org/x/tools/gopls/internal/protocol"

// Modification represents a modification to a file.
type Modification struct {
	URI    protocol.DocumentURI
	Action Action

	// OnDisk is true if a watched file is changed on disk.
	// If true, Version will be -1 and Text will be nil.
	OnDisk bool

	// Version will be -1 and Text will be nil when they are not supplied,
	// specifically on textDocument/didClose and for on-disk changes.
	Version int32
	Text    []byte

	// LanguageID is only sent from the language client on textDocument/didOpen.
	LanguageID protocol.LanguageKind
}

// An Action is a type of file state change.
type Action int

const (
	UnknownAction = Action(iota)
	Open
	Change
	Close
	Save
	Create
	Delete
)

func (a Action) String() string {
	switch a {
	case Open:
		return "Open"
	case Change:
		return "Change"
	case Close:
		return "Close"
	case Save:
		return "Save"
	case Create:
		return "Create"
	case Delete:
		return "Delete"
	default:
		return "Unknown"
	}
}


================================================
FILE: gopls/internal/filecache/filecache.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The filecache package provides a file-based shared durable blob cache.
//
// The cache is a machine-global mapping from (kind string, key
// [32]byte) to []byte, where kind is an identifier describing the
// namespace or purpose (e.g. "analysis"), and key is a SHA-256 digest
// of the recipe of the value. (It need not be the digest of the value
// itself, so you can query the cache without knowing what value the
// recipe would produce.)
//
// The space budget of the cache can be controlled by [SetBudget].
// Cache entries may be evicted at any time or in any order.
// Note that "du -sh $GOPLSCACHE" may report a disk usage
// figure that is rather larger (e.g. 50%) than the budget because
// it rounds up partial disk blocks.
//
// The Get and Set operations are concurrency-safe.
package filecache

import (
	"bytes"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/lru"
)

// Start causes the filecache to initialize and start garbage gollection.
//
// Start is automatically called by the first call to Get, but may be called
// explicitly to pre-initialize the cache.
func Start() {
	go getCacheDir()
}

// As an optimization, use a 100MB in-memory LRU cache in front of filecache
// operations. This reduces I/O for operations such as diagnostics or
// implementations that repeatedly access the same cache entries.
var memCache = lru.New[memKey, []byte](100 * 1e6)

type memKey struct {
	kind string
	key  [32]byte
}

// Get retrieves from the cache and returns the value most recently
// supplied to Set(kind, key), possibly by another process.
//
// Get returns ErrNotFound if the value was not found. The first call
// to Get may fail due to ENOSPC or deletion of the process's
// executable. Other causes of failure include deletion or corruption
// of the cache (by external meddling) while gopls is running, or
// faulty hardware; see issue #67433.
//
// Callers should not modify the returned array.
func Get(kind string, key [32]byte) ([]byte, error) {
	// First consult the read-through memory cache.
	// Note that memory cache hits do not update the times
	// used for LRU eviction of the file-based cache.
	if value, ok := memCache.Get(memKey{kind, key}); ok {
		return value, nil
	}

	iolimit <- struct{}{}        // acquire a token
	defer func() { <-iolimit }() // release a token

	// Read the index file, which provides the name of the CAS file.
	indexName, err := filename(kind, key)
	if err != nil {
		// e.g. ENOSPC, deletion of executable (first time only);
		// deletion of cache (at any time).
		return nil, err
	}
	indexData, err := os.ReadFile(indexName)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return nil, ErrNotFound
		}
		return nil, err
	}
	var valueHash [32]byte
	if copy(valueHash[:], indexData) != len(valueHash) {
		return nil, ErrNotFound // index entry has wrong length
	}

	// Read the CAS file and check its contents match.
	//
	// This ensures integrity in all cases (corrupt or truncated
	// file, short read, I/O error, wrong length, etc) except an
	// engineered hash collision, which is infeasible.
	casName, err := filename(casKind, valueHash)
	if err != nil {
		return nil, err // see above for possible causes
	}
	value, _ := os.ReadFile(casName) // ignore error
	if sha256.Sum256(value) != valueHash {
		return nil, ErrNotFound // CAS file is missing or has wrong contents
	}

	// Update file times used by LRU eviction.
	//
	// Because this turns a read into a write operation,
	// we follow the approach used in the go command's
	// cache and update the access time only if the
	// existing timestamp is older than one hour.
	//
	// (Traditionally the access time would be updated
	// automatically, but for efficiency most POSIX systems have
	// for many years set the noatime mount option to avoid every
	// open or read operation entailing a metadata write.)
	touch(indexName, casName)

	memCache.Set(memKey{kind, key}, value, len(value))

	return value, nil
}

// ErrNotFound is the distinguished error
// returned by Get when the key is not found.
var ErrNotFound = fmt.Errorf("not found")

// Set updates the value in the cache.
//
// Set may fail due to:
// - failure to access/create the cache (first call only);
// - out of space (ENOSPC);
// - deletion of the cache concurrent with a call to Set;
// - faulty hardware.
// See issue #67433.
func Set(kind string, key [32]byte, value []byte) error {
	memCache.Set(memKey{kind, key}, value, len(value))

	// Set the active event to wake up the GC.
	select {
	case active <- struct{}{}:
	default:
	}

	iolimit <- struct{}{}        // acquire a token
	defer func() { <-iolimit }() // release a token

	// First, add the value to the content-
	// addressable store (CAS), if not present.
	hash := sha256.Sum256(value)
	casName, err := filename(casKind, hash)
	if err != nil {
		return err
	}
	// Does CAS file exist and have correct (complete) content?
	// TODO(adonovan): opt: use mmap for this check.
	if prev, _ := os.ReadFile(casName); !bytes.Equal(prev, value) {
		if err := os.MkdirAll(filepath.Dir(casName), 0700); err != nil {
			return err
		}
		// Avoiding O_TRUNC here is merely an optimization to avoid
		// cache misses when two threads race to write the same file.
		if err := writeFileNoTrunc(casName, value, 0600); err != nil {
			os.Remove(casName) // ignore error
			return err         // e.g. disk full
		}
	}

	// Now write an index entry that refers to the CAS file.
	indexName, err := filename(kind, key)
	if err != nil {
		return err
	}
	if err := os.MkdirAll(filepath.Dir(indexName), 0700); err != nil {
		return err
	}
	if err := writeFileNoTrunc(indexName, hash[:], 0600); err != nil {
		os.Remove(indexName) // ignore error
		return err           // e.g. disk full
	}

	// Update the CAS file's timestamp to prevent premature LRU eviction.
	touch(casName)

	return nil
}

func touch(filenames ...string) {
	now := time.Now()
	for _, filename := range filenames {
		st, err := os.Stat(filename)
		if err == nil && now.Sub(st.ModTime()) > time.Hour {
			os.Chtimes(filename, now, now) // ignore error
		}
	}
}

// The active 1-channel is a selectable resettable event
// indicating recent cache activity.
var active = make(chan struct{}, 1)

// writeFileNoTrunc is like os.WriteFile but doesn't truncate until
// after the write, so that racing writes of the same data are idempotent.
func writeFileNoTrunc(filename string, data []byte, perm os.FileMode) error {
	f, err := os.OpenFile(filename, os.O_WRONLY|os.O_CREATE, perm)
	if err != nil {
		return err
	}
	_, err = f.Write(data)
	if err == nil {
		err = f.Truncate(int64(len(data)))
	}
	if closeErr := f.Close(); err == nil {
		err = closeErr
	}
	return err
}

// reserved kind strings
const (
	casKind = "cas" // content-addressable store files
	bugKind = "bug" // gopls bug reports
)

var iolimit = make(chan struct{}, 128) // counting semaphore to limit I/O concurrency in Set.

var budget int64 = 1e9 // 1GB

// SetBudget sets a soft limit on disk usage of regular files in the
// cache (in bytes) and returns the previous value. Supplying a
// negative value queries the current value without changing it.
//
// If two gopls processes have different budgets, the one with the
// lower budget will collect garbage more actively, but both will
// observe the effect.
//
// Even in the steady state, the storage usage reported by the 'du'
// command may exceed the budget by as much as a factor of 3 due to
// the overheads of directories and the effects of block quantization,
// which are especially pronounced for the small index files.
func SetBudget(new int64) (old int64) {
	if new < 0 {
		return atomic.LoadInt64(&budget)
	}
	return atomic.SwapInt64(&budget, new)
}

// --- implementation ----

// filename returns the name of the cache file of the specified kind and key.
//
// A typical cache file has a name such as:
//
//	$HOME/Library/Caches / gopls / VVVVVVVV / KK / KKKK...KKKK - kind
//
// The portions separated by spaces are as follows:
// - The user's preferred cache directory; the default value varies by OS.
// - The constant "gopls".
// - The "version", 32 bits of the digest of the gopls executable.
// - The first 8 bits of the key, to avoid huge directories.
// - The full 256 bits of the key.
// - The kind or purpose of this cache file (e.g. "analysis").
//
// The kind establishes a namespace for the keys. It is represented as
// a suffix, not a segment, as this significantly reduces the number
// of directories created, and thus the storage overhead.
//
// Previous iterations of the design aimed for the invariant that once
// a file is written, its contents are never modified, though it may
// be atomically replaced or removed. However, not all platforms have
// an atomic rename operation (our first approach), and file locking
// (our second) is a notoriously fickle mechanism.
//
// The current design instead exploits a trick from the cache
// implementation used by the go command: writes of small files are in
// practice atomic (all or nothing) on all platforms.
// (See GOROOT/src/cmd/go/internal/cache/cache.go.)
//
// Russ Cox notes: "all file systems use an rwlock around every file
// system block, including data blocks, so any writes or reads within
// the same block are going to be handled atomically by the FS
// implementation without any need to request file locking explicitly.
// And since the files are so small, there's only one block. (A block
// is at minimum 512 bytes, usually much more.)" And: "all modern file
// systems protect against [partial writes due to power loss] with
// journals."
//
// We use a two-level scheme consisting of an index and a
// content-addressable store (CAS). A single cache entry consists of
// two files. The value of a cache entry is written into the file at
// filename("cas", sha256(value)). Since the value may be arbitrarily
// large, this write is not atomic. That means we must check the
// integrity of the contents read back from the CAS to make sure they
// hash to the expected key. If the CAS file is incomplete or
// inconsistent, we proceed as if it were missing.
//
// Once the CAS file has been written, we write a small fixed-size
// index file at filename(kind, key), using the values supplied by the
// caller. The index file contains the hash that identifies the value
// file in the CAS. (We could add extra metadata to this file, up to
// 512B, the minimum size of a disk block, if later desired, so long
// as the total size remains fixed.) Because the index file is small,
// concurrent writes to it are atomic in practice, even though this is
// not guaranteed by any OS. The fixed size ensures that readers can't
// see a palimpsest when a short new file overwrites a longer old one.
//
// New versions of gopls are free to reorganize the contents of the
// version directory as needs evolve.  But all versions of gopls must
// in perpetuity treat the "gopls" directory in a common fashion.
//
// In particular, each gopls process attempts to garbage collect
// the entire gopls directory so that newer binaries can clean up
// after older ones: in the development cycle especially, new
// versions may be created frequently.
func filename(kind string, key [32]byte) (string, error) {
	base := fmt.Sprintf("%x-%s", key, kind)
	dir, err := getCacheDir()
	if err != nil {
		return "", err
	}
	// Keep the BugReports function consistent with this one.
	return filepath.Join(dir, base[:2], base), nil
}

// getCacheDir returns the persistent cache directory of all processes
// running this version of the gopls executable.
//
// It must incorporate the hash of the executable so that we needn't
// worry about incompatible changes to the file format or changes to
// the algorithm that produced the index.
func getCacheDir() (string, error) {
	cacheDirOnce.Do(func() {
		// Use user's preferred cache directory.
		userDir := os.Getenv("GOPLSCACHE")
		if userDir == "" {
			var err error
			userDir, err = os.UserCacheDir()
			if err != nil {
				userDir = os.TempDir()
			}
		}
		goplsDir := filepath.Join(userDir, "gopls")

		// UserCacheDir may return a nonexistent directory
		// (in which case we must create it, which may fail),
		// or it may return a non-writable directory, in
		// which case we should ideally respect the user's express
		// wishes (e.g. XDG_CACHE_HOME) and not write somewhere else.
		// Sadly UserCacheDir doesn't currently let us distinguish
		// such intent from accidental misconfiguraton such as HOME=/
		// in a CI builder. So, we check whether the gopls subdirectory
		// can be created (or already exists) and not fall back to /tmp.
		// See also https://github.com/golang/go/issues/57638.
		if os.MkdirAll(goplsDir, 0700) != nil {
			goplsDir = filepath.Join(os.TempDir(), "gopls")
		}

		// Start the garbage collector.
		go gc(goplsDir)

		// Compute the hash of this executable (~20ms) and create a subdirectory.
		hash, err := hashExecutable()
		if err != nil {
			cacheDirErr = fmt.Errorf("can't hash gopls executable: %w", err)
		}
		// Use only 32 bits of the digest to avoid unwieldy filenames.
		// It's not an adversarial situation.
		cacheDir = filepath.Join(goplsDir, fmt.Sprintf("%x", hash[:4]))
		if err := os.MkdirAll(cacheDir, 0700); err != nil {
			cacheDirErr = fmt.Errorf("can't create cache: %w", err)
		}
	})
	return cacheDir, cacheDirErr
}

var (
	cacheDirOnce sync.Once
	cacheDir     string
	cacheDirErr  error
)

func hashExecutable() (hash [32]byte, err error) {
	exe, err := os.Executable()
	if err != nil {
		return hash, err
	}
	f, err := os.Open(exe)
	if err != nil {
		return hash, err
	}
	defer f.Close()
	h := sha256.New()
	if _, err := io.Copy(h, f); err != nil {
		return hash, fmt.Errorf("can't read executable: %w", err)
	}
	h.Sum(hash[:0])
	return hash, nil
}

// gc runs forever, periodically deleting files from the gopls
// directory until the space budget is no longer exceeded, and also
// deleting files older than the maximum age, regardless of budget.
//
// One gopls process may delete garbage created by a different gopls
// process, possibly running a different version of gopls, possibly
// running concurrently.
func gc(goplsDir string) {
	// period between collections
	//
	// Originally the period was always 1 minute, but this
	// consumed 15% of a CPU core when idle (#61049).
	//
	// The reason for running collections even when idle is so
	// that long lived gopls sessions eventually clean up the
	// caches created by defunct executables.
	const (
		minPeriod = 5 * time.Minute // when active
		maxPeriod = 6 * time.Hour   // when idle
	)

	// Sleep statDelay*batchSize between stats to smooth out I/O.
	//
	// The constants below were chosen using the following heuristics:
	//  - 1GB of filecache is on the order of ~100-200k files, in which case
	//    100μs delay per file introduces 10-20s of additional walk time,
	//    less than the minPeriod.
	//  - Processing batches of stats at once is much more efficient than
	//    sleeping after every stat (due to OS optimizations).
	const statDelay = 100 * time.Microsecond // average delay between stats, to smooth out I/O
	const batchSize = 1000                   // # of stats to process before sleeping
	const maxAge = 5 * 24 * time.Hour        // max time since last access before file is deleted

	// The macOS filesystem is strikingly slow, at least on some machines.
	// /usr/bin/find achieves only about 25,000 stats per second
	// at full speed (no pause between items), meaning a large
	// cache may take several minutes to scan.
	//
	// (gopls' caches should never actually get this big in
	// practice: the example mentioned above resulted from a bug
	// that caused filecache to fail to delete any files.)

	const debug = false

	// Names of all directories found in first pass; nil thereafter.
	dirs := make(map[string]bool)

	for {
		// Wait unconditionally for the minimum period.
		// We do this even on the first run so that tests
		// don't (all) run the GC.
		time.Sleep(minPeriod)

		// Enumerate all files in the cache.
		type item struct {
			path  string
			mtime time.Time
			size  int64
		}
		var files []item
		start := time.Now()
		var total int64 // bytes
		_ = filepath.Walk(goplsDir, func(path string, stat os.FileInfo, err error) error {
			if err != nil {
				return nil // ignore errors
			}
			if stat.IsDir() {
				// Collect (potentially empty) directories.
				if dirs != nil {
					dirs[path] = true
				}
			} else {
				// Unconditionally delete files we haven't used in ages.
				age := time.Since(stat.ModTime())
				if age > maxAge {
					if debug {
						log.Printf("age: deleting stale file %s (%dB, age %v)",
							path, stat.Size(), age)
					}
					os.Remove(path) // ignore error
				} else {
					files = append(files, item{path, stat.ModTime(), stat.Size()})
					total += stat.Size()
					if debug && len(files)%1000 == 0 {
						log.Printf("filecache: checked %d files in %v", len(files), time.Since(start))
					}
					if len(files)%batchSize == 0 {
						time.Sleep(batchSize * statDelay)
					}
				}
			}
			return nil
		})

		// Sort oldest files first.
		sort.Slice(files, func(i, j int) bool {
			return files[i].mtime.Before(files[j].mtime)
		})

		// Delete oldest files until we're under budget.
		budget := atomic.LoadInt64(&budget)
		for _, file := range files {
			if total < budget {
				break
			}
			if debug {
				age := time.Since(file.mtime)
				log.Printf("budget: deleting stale file %s (%dB, age %v)",
					file.path, file.size, age)
			}
			os.Remove(file.path) // ignore error
			total -= file.size
		}
		files = nil // release memory before sleep

		// Once only, delete all directories.
		// This will succeed only for the empty ones,
		// and ensures that stale directories (whose
		// files have been deleted) are removed eventually.
		// They don't take up much space but they do slow
		// down the traversal.
		//
		// We do this after the sleep to minimize the
		// race against Set, which may create a directory
		// that is momentarily empty.
		//
		// (Test processes don't live that long, so
		// this may not be reached on the CI builders.)
		if dirs != nil {
			dirnames := make([]string, 0, len(dirs))
			for dir := range dirs {
				dirnames = append(dirnames, dir)
			}
			dirs = nil

			// Descending length order => children before parents.
			sort.Slice(dirnames, func(i, j int) bool {
				return len(dirnames[i]) > len(dirnames[j])
			})
			var deleted int
			for _, dir := range dirnames {
				if os.Remove(dir) == nil { // ignore error
					deleted++
				}
			}
			if debug {
				log.Printf("deleted %d empty directories", deleted)
			}
		}

		// Wait up to the max period,
		// or for Set activity in this process.
		select {
		case <-active:
		case <-time.After(maxPeriod):
		}
	}
}

func init() {
	// Register a handler to durably record this process's first
	// assertion failure in the cache so that we can ask users to
	// share this information via the stats command.
	bug.Handle(func(bug bug.Bug) {
		// Wait for cache init (bugs in tests happen early).
		_, _ = getCacheDir()

		data, err := json.Marshal(bug)
		if err != nil {
			panic(fmt.Sprintf("error marshalling bug %+v: %v", bug, err))
		}

		key := sha256.Sum256(data)
		_ = Set(bugKind, key, data)
	})
}

// BugReports returns a new unordered array of the contents
// of all cached bug reports produced by this executable.
// It also returns the location of the cache directory
// used by this process (or "" on initialization error).
func BugReports() (string, []bug.Bug) {
	// To test this logic, run:
	// $ TEST_GOPLS_BUG=oops gopls bug     # trigger a bug
	// $ gopls stats                       # list the bugs

	dir, err := getCacheDir()
	if err != nil {
		return "", nil // ignore initialization errors
	}
	var result []bug.Bug
	_ = filepath.Walk(dir, func(path string, info fs.FileInfo, err error) error {
		if err != nil {
			return nil // ignore readdir/stat errors
		}
		// Parse the key from each "XXXX-bug" cache file name.
		if !info.IsDir() && strings.HasSuffix(path, bugKind) {
			var key [32]byte
			n, err := hex.Decode(key[:], []byte(filepath.Base(path)[:len(key)*2]))
			if err != nil || n != len(key) {
				return nil // ignore malformed file names
			}
			content, err := Get(bugKind, key)
			if err == nil { // ignore read errors
				var b bug.Bug
				if err := json.Unmarshal(content, &b); err != nil {
					log.Printf("error marshalling bug %q: %v", string(content), err)
				}
				result = append(result, b)
			}
		}
		return nil
	})
	return dir, result
}


================================================
FILE: gopls/internal/filecache/filecache_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package filecache_test

// This file defines tests of the API of the filecache package.
//
// Some properties (e.g. garbage collection) cannot be exercised
// through the API, so this test does not attempt to do so.

import (
	"bytes"
	cryptorand "crypto/rand"
	"fmt"
	"log"
	mathrand "math/rand"
	"os"
	"os/exec"
	"strconv"
	"strings"
	"testing"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/internal/testenv"
)

func TestBasics(t *testing.T) {
	const kind = "TestBasics"
	key := uniqueKey() // never used before
	value := []byte("hello")

	// Get of a never-seen key returns not found.
	if _, err := filecache.Get(kind, key); err != filecache.ErrNotFound {
		if strings.Contains(err.Error(), "operation not supported") ||
			strings.Contains(err.Error(), "not implemented") {
			t.Skipf("skipping: %v", err)
		}
		t.Errorf("Get of random key returned err=%q, want not found", err)
	}

	// Set of a never-seen key and a small value succeeds.
	if err := filecache.Set(kind, key, value); err != nil {
		t.Errorf("Set failed: %v", err)
	}

	// Get of the key returns a copy of the value.
	if got, err := filecache.Get(kind, key); err != nil {
		t.Errorf("Get after Set failed: %v", err)
	} else if string(got) != string(value) {
		t.Errorf("Get after Set returned different value: got %q, want %q", got, value)
	}

	// The kind is effectively part of the key.
	if _, err := filecache.Get("different-kind", key); err != filecache.ErrNotFound {
		t.Errorf("Get with wrong kind returned err=%q, want not found", err)
	}
}

// TestConcurrency exercises concurrent access to the same entry.
func TestConcurrency(t *testing.T) {
	if os.Getenv("GO_BUILDER_NAME") == "plan9-arm" {
		t.Skip(`skipping on plan9-arm builder due to golang/go#58748: failing with 'mount rpc error'`)
	}
	const kind = "TestConcurrency"
	key := uniqueKey()
	const N = 100 // concurrency level

	// Construct N distinct values, each larger
	// than a typical 4KB OS file buffer page.
	var values [N][8192]byte
	for i := range values {
		if _, err := mathrand.Read(values[i][:]); err != nil {
			t.Fatalf("rand: %v", err)
		}
	}

	// get calls Get and verifies that the cache entry
	// matches one of the values passed to Set.
	get := func(mustBeFound bool) error {
		got, err := filecache.Get(kind, key)
		if err != nil {
			if err == filecache.ErrNotFound && !mustBeFound {
				return nil // not found
			}
			return err
		}
		for _, want := range values {
			if bytes.Equal(want[:], got) {
				return nil // a match
			}
		}
		return fmt.Errorf("Get returned a value that was never Set")
	}

	// Perform N concurrent calls to Set and Get.
	// All sets must succeed.
	// All gets must return nothing, or one of the Set values;
	// there is no third possibility.
	var group errgroup.Group
	for i := range values {
		group.Go(func() error { return filecache.Set(kind, key, values[i][:]) })
		group.Go(func() error { return get(false) })
	}
	if err := group.Wait(); err != nil {
		if strings.Contains(err.Error(), "operation not supported") ||
			strings.Contains(err.Error(), "not implemented") {
			t.Skipf("skipping: %v", err)
		}
		t.Fatal(err)
	}

	// A final Get must report one of the values that was Set.
	if err := get(true); err != nil {
		t.Fatalf("final Get failed: %v", err)
	}
}

const (
	testIPCKind   = "TestIPC"
	testIPCValueA = "hello"
	testIPCValueB = "world"
)

// TestIPC exercises interprocess communication through the cache.
// It calls Set(A) in the parent, { Get(A); Set(B) } in the child
// process, then Get(B) in the parent.
func TestIPC(t *testing.T) {
	testenv.NeedsExec(t)

	keyA := uniqueKey()
	keyB := uniqueKey()
	value := []byte(testIPCValueA)

	// Set keyA.
	if err := filecache.Set(testIPCKind, keyA, value); err != nil {
		if strings.Contains(err.Error(), "operation not supported") {
			t.Skipf("skipping: %v", err)
		}
		t.Fatalf("Set: %v", err)
	}

	// Call ipcChild in a child process,
	// passing it the keys in the environment
	// (quoted, to avoid NUL termination of C strings).
	// It will Get(A) then Set(B).
	cmd := exec.Command(os.Args[0], os.Args[1:]...)
	cmd.Env = append(os.Environ(),
		"ENTRYPOINT=ipcChild",
		fmt.Sprintf("KEYA=%q", keyA),
		fmt.Sprintf("KEYB=%q", keyB))
	cmd.Stdout = os.Stderr
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		t.Fatal(err)
	}

	// Verify keyB.
	got, err := filecache.Get(testIPCKind, keyB)
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != "world" {
		t.Fatalf("Get(keyB) = %q, want %q", got, "world")
	}
}

// We define our own main function so that portions of
// some tests can run in a separate (child) process.
func TestMain(m *testing.M) {
	switch os.Getenv("ENTRYPOINT") {
	case "ipcChild":
		ipcChild()
	default:
		os.Exit(m.Run())
	}
}

// ipcChild is the portion of TestIPC that runs in a child process.
func ipcChild() {
	getenv := func(name string) (key [32]byte) {
		s, _ := strconv.Unquote(os.Getenv(name))
		copy(key[:], []byte(s))
		return
	}

	// Verify key A.
	got, err := filecache.Get(testIPCKind, getenv("KEYA"))
	if err != nil || string(got) != testIPCValueA {
		log.Fatalf("child: Get(key) = %q, %v; want %q", got, err, testIPCValueA)
	}

	// Set key B.
	if err := filecache.Set(testIPCKind, getenv("KEYB"), []byte(testIPCValueB)); err != nil {
		log.Fatalf("child: Set(keyB) failed: %v", err)
	}
}

// uniqueKey returns a key that has never been used before.
func uniqueKey() (key [32]byte) {
	if _, err := cryptorand.Read(key[:]); err != nil {
		log.Fatalf("rand: %v", err)
	}
	return
}

func BenchmarkUncontendedGet(b *testing.B) {
	const kind = "BenchmarkUncontendedGet"
	key := uniqueKey()

	var value [8192]byte
	if _, err := mathrand.Read(value[:]); err != nil {
		b.Fatalf("rand: %v", err)
	}
	if err := filecache.Set(kind, key, value[:]); err != nil {
		b.Fatal(err)
	}

	b.SetBytes(int64(len(value)))

	var group errgroup.Group
	group.SetLimit(50)
	for b.Loop() {
		group.Go(func() error {
			_, err := filecache.Get(kind, key)
			return err
		})
	}
	if err := group.Wait(); err != nil {
		b.Fatal(err)
	}
}

// These two benchmarks are asymmetric: the one for Get imposes a
// modest bound on concurrency (50) whereas the one for Set imposes a
// much higher concurrency (1000) to test the implementation's
// self-imposed bound.

func BenchmarkUncontendedSet(b *testing.B) {
	const kind = "BenchmarkUncontendedSet"
	key := uniqueKey()
	var value [8192]byte

	const P = 1000 // parallelism
	b.SetBytes(P * int64(len(value)))

	for b.Loop() {
		// Perform P concurrent calls to Set. All must succeed.
		var group errgroup.Group
		for range [P]bool{} {
			group.Go(func() error {
				return filecache.Set(kind, key, value[:])
			})
		}
		if err := group.Wait(); err != nil {
			if strings.Contains(err.Error(), "operation not supported") ||
				strings.Contains(err.Error(), "not implemented") {
				b.Skipf("skipping: %v", err)
			}
			b.Fatal(err)
		}
	}
}


================================================
FILE: gopls/internal/filewatcher/export_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package filewatcher

// This file defines things (and opens backdoors) needed only by tests.

// SetAfterAddHook sets a hook to be called after a path is added to the watcher.
// This is used in tests to inspect the error returned by the underlying watcher.
func SetAfterAddHook(f func(string, error)) {
	afterAddHook = f
}


================================================
FILE: gopls/internal/filewatcher/filewatcher.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package filewatcher

import (
	"fmt"
	"log/slog"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
)

// Watcher monitors file system events.
type Watcher interface {
	// WatchDir adds a directory to the set of watched directories.
	WatchDir(path string) error

	// Close stops the watcher and releases any associated resources.
	Close() error

	// Poke signals the watcher to prioritize a scan, if applicable.
	// This is used to implement adaptive polling.
	Poke()
}

// New creates a new file watcher and starts its event-handling loop. The
// [Watcher.Close] method must be called to clean up resources.
//
// The provided event handler is called sequentially with a batch of file events,
// but the error handler is called concurrently. The watcher blocks until the
// handler returns, so the handlers should be fast and non-blocking.
//
// TODO(hxjiang): replace mode string to enum.
func New(mode string, interval time.Duration, logger *slog.Logger, onEvents func([]protocol.FileEvent), onError func(error)) (Watcher, error) {
	switch mode {
	// TODO (hxjiang): support poll watcher.
	case "fsnotify":
		return NewFSNotifyWatcher(interval, logger, onEvents, onError)
	}
	// TODO(hxjiang): support "auto" mode.
	return nil, fmt.Errorf("unknown FileWatcher mode: %q", mode)
}


================================================
FILE: gopls/internal/filewatcher/filewatcher_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package filewatcher_test

import (
	"cmp"
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"testing"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/filewatcher"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/txtar"
)

func TestFileWatcher(t *testing.T) {
	switch runtime.GOOS {
	case "darwin", "linux", "windows":
	default:
		t.Skip("unsupported OS")
	}

	testCases := []struct {
		name           string
		goos           []string // if not empty, only run in these OS.
		initWorkspace  string
		changes        func(root string) error
		expectedEvents []protocol.FileEvent
	}{
		{
			name: "create file in darwin",
			goos: []string{"darwin"},
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.WriteFile(filepath.Join(root, "bar.go"), []byte("package main"), 0644)
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "bar.go", Type: protocol.Created},
			},
		},
		{
			name: "create file in linux & windows",
			goos: []string{"linux", "windows"},
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.WriteFile(filepath.Join(root, "bar.go"), []byte("package main"), 0644)
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "bar.go", Type: protocol.Created},
				{URI: "bar.go", Type: protocol.Changed},
			},
		},
		{
			name: "modify file",
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.WriteFile(filepath.Join(root, "foo.go"), []byte("package main // modified"), 0644)
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "foo.go", Type: protocol.Changed},
			},
		},
		{
			name: "delete file",
			initWorkspace: `
-- foo.go --
package foo
-- bar.go --
package bar
`,
			changes: func(root string) error {
				return os.Remove(filepath.Join(root, "foo.go"))
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "foo.go", Type: protocol.Deleted},
			},
		},
		{
			name: "rename file in linux & windows",
			goos: []string{"linux", "windows"},
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.Rename(filepath.Join(root, "foo.go"), filepath.Join(root, "bar.go"))
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "foo.go", Type: protocol.Deleted},
				{URI: "bar.go", Type: protocol.Created},
			},
		},
		{
			name: "rename file in darwin",
			goos: []string{"darwin"},
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.Rename(filepath.Join(root, "foo.go"), filepath.Join(root, "bar.go"))
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "bar.go", Type: protocol.Created},
				{URI: "foo.go", Type: protocol.Deleted},
			},
		},
		{
			name: "create directory",
			initWorkspace: `
-- foo.go --
package foo
`,
			changes: func(root string) error {
				return os.Mkdir(filepath.Join(root, "bar"), 0755)
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "bar", Type: protocol.Created},
			},
		},
		{
			name: "delete directory",
			initWorkspace: `
-- foo/bar.go --
package foo
`,
			changes: func(root string) error {
				return os.RemoveAll(filepath.Join(root, "foo"))
			},
			expectedEvents: []protocol.FileEvent{
				// We only assert that the directory deletion event exists,
				// because file system event behavior is inconsistent across
				// platforms when deleting a non-empty directory.
				// e.g. windows-amd64 may only emit a single dir removal event,
				// freebsd-amd64 report dir removal before file removal,
				// linux-amd64 report the reverse order.
				// Therefore, the most reliable and cross-platform compatible
				// signal is the deletion event for the directory itself.
				{URI: "foo", Type: protocol.Deleted},
			},
		},
		{
			name: "rename directory in linux & windows",
			goos: []string{"linux", "windows"},
			initWorkspace: `
-- foo/bar.go --
package foo
`,
			changes: func(root string) error {
				return os.Rename(filepath.Join(root, "foo"), filepath.Join(root, "baz"))
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "foo", Type: protocol.Deleted},
				{URI: "baz", Type: protocol.Created},
				{URI: "baz/bar.go", Type: protocol.Created},
			},
		},
		{
			name: "rename directory in darwin",
			goos: []string{"darwin"},
			initWorkspace: `
-- foo/bar.go --
package foo
`,
			changes: func(root string) error {
				return os.Rename(filepath.Join(root, "foo"), filepath.Join(root, "baz"))
			},
			expectedEvents: []protocol.FileEvent{
				{URI: "baz", Type: protocol.Created},
				{URI: "baz/bar.go", Type: protocol.Created},
				{URI: "foo", Type: protocol.Deleted},
			},
		},
		// TODO(hxjiang): test for symlink to a dir.
	}

	for _, tt := range testCases {
		t.Run(tt.name, func(t *testing.T) {
			if len(tt.goos) > 0 && !slices.Contains(tt.goos, runtime.GOOS) {
				t.Skipf("skipping on %s", runtime.GOOS)
			}

			root := t.TempDir()

			archive := txtar.Parse([]byte(tt.initWorkspace))
			for _, f := range archive.Files {
				path := filepath.Join(root, f.Name)
				if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
					t.Fatal(err)
				}
				if err := os.WriteFile(path, f.Data, 0644); err != nil {
					t.Fatal(err)
				}
			}

			foundAll := make(chan struct{})
			var gots []protocol.FileEvent

			matched := 0
			eventsHandler := func(events []protocol.FileEvent) {
				gots = append(gots, events...)

				if matched == len(tt.expectedEvents) {
					return
				}

				// This verifies that the list of wanted events is a subsequence of
				// the received events. It confirms not only that all wanted events
				// are present, but also that their relative order is preserved.
				for _, got := range events {
					want := protocol.FileEvent{
						URI:  protocol.URIFromPath(filepath.Join(root, string(tt.expectedEvents[matched].URI))),
						Type: tt.expectedEvents[matched].Type,
					}
					if want == got {
						matched++
					}
					if matched == len(tt.expectedEvents) {
						close(foundAll)
						return
					}
				}

			}
			errHandler := func(err error) {
				t.Errorf("error from watcher: %v", err)
			}
			w, err := filewatcher.New("fsnotify", 50*time.Millisecond, nil, eventsHandler, errHandler)
			if err != nil {
				t.Fatal(err)
			}
			defer func() {
				if err := w.Close(); err != nil {
					t.Errorf("failed to close the file watcher: %v", err)
				}
			}()

			if err := w.WatchDir(root); err != nil {
				t.Fatal(err)
			}

			if tt.changes != nil {
				if err := tt.changes(root); err != nil {
					t.Fatal(err)
				}
			}

			select {
			case <-foundAll:
			case <-time.After(30 * time.Second):
				if matched != len(tt.expectedEvents) {
					var want strings.Builder
					for _, e := range tt.expectedEvents {
						want.WriteString(fmt.Sprintf("URI: %s type: %v\n", e.URI, e.Type))
					}
					var got strings.Builder
					for _, e := range gots {
						got.WriteString(fmt.Sprintf("URI: %s type: %v\n", strings.TrimPrefix(e.URI.Path(), root+"/"), e.Type))
					}
					t.Errorf("found %v matching events slice\nwant sequences:\n%s\nall got:\n%s", matched, want.String(), got.String())
				}

			}
		})
	}
}

func TestBrokenSymlink(t *testing.T) {
	if runtime.GOOS != "darwin" {
		t.Skip("unsupported OS")
	}

	root := t.TempDir()

	// watchErrs is used to capture watch errors during directory monitoring.
	// This mechanism allows the test to assert that specific directory watches
	// initially fail and subsequently recover upon fixing the broken symlink.
	watchErrs := make(chan error, 10)
	filewatcher.SetAfterAddHook(func(path string, watchErr error) {
		rel, err := filepath.Rel(root, path)
		if err != nil {
			return
		}
		if rel == "foo" {
			if watchErr == nil {
				close(watchErrs)
			} else {
				watchErrs <- watchErr
			}
		}
	})
	defer filewatcher.SetAfterAddHook(nil)

	var (
		gots     []protocol.FileEvent
		matched  int
		foundAll = make(chan struct{})
	)
	wants := []protocol.FileEvent{
		// "foo" create event from fsnotify and synthesized create event
		// for all entries under foo.
		{URI: "foo", Type: protocol.Created},
		{URI: "foo/a.go", Type: protocol.Created},
		{URI: "foo/b.go", Type: protocol.Created},
		{URI: "foo/from.go", Type: protocol.Created},
		// "to.go" creation from fsnotify.
		{URI: "to.go", Type: protocol.Created},
		// file creation event after watch retry succeeded.
		{URI: "foo/new.go", Type: protocol.Created},
	}
	eventsHandler := func(events []protocol.FileEvent) {
		gots = append(gots, events...)

		if matched == len(wants) {
			return
		}

		for _, got := range events {
			want := protocol.FileEvent{
				URI:  protocol.URIFromPath(filepath.Join(root, string(wants[matched].URI))),
				Type: wants[matched].Type,
			}
			if want == got {
				matched++
			}
			if matched == len(wants) {
				close(foundAll)
				return
			}
		}

	}
	errHandler := func(err error) {
		t.Errorf("error from watcher: %v", err)
	}
	w, err := filewatcher.New("fsnotify", 50*time.Millisecond, nil, eventsHandler, errHandler)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := w.Close(); err != nil {
			t.Errorf("failed to close the file watcher: %v", err)
		}
	}()

	if err := w.WatchDir(root); err != nil {
		t.Fatal(err)
	}

	{
		// Prepare a dir with with broken symbolic link.
		// foo                       <- 1st
		// ├── from.go -> root/to.go <- 1st
		// ├── a.go                  <- 1st
		// └── b.go                  <- 1st

		to := filepath.Join(root, "to.go")

		archive := txtar.Parse([]byte(`
-- a.go --
package a
-- b.go --
package b
`))
		tmp := filepath.Join(t.TempDir(), "foo")
		for _, f := range archive.Files {
			path := filepath.Join(tmp, f.Name)
			if err := os.MkdirAll(filepath.Dir(path), 0755); err != nil {
				t.Fatalf("fail to create dir %v", err)
			}
			if err := os.WriteFile(path, f.Data, 0644); err != nil {
				t.Fatalf("fail to write file %v", err)
			}
		}

		// Create the symbolic link to a non-existing file. This would
		// cause the watch registration for dir "foo" to fail.
		if err := os.Symlink(to, filepath.Join(tmp, "from.go")); err != nil {
			t.Fatalf("fail to create symlink file %v", err)
		}

		// Move the directory containing the broken symlink into place
		// to avoids a flaky test where the directory could be watched
		// before the symlink is created. See golang/go#74782.
		if err := os.Rename(tmp, filepath.Join(root, "foo")); err != nil {
			t.Fatalf("fail to rename file %v", err)
		}

		// root
		// ├── foo                          <- 2nd (Move)
		// │   ├── a.go                     <- 2nd (Move)
		// │   ├── b.go                     <- 2nd (Move)
		// │   ├── from.go -> ../../to.go   <- 2nd (Move)
		// │   └── new.go                   <- 4th (Create)
		// └── to.go                        <- 3rd (Create)

		// Should be able to capture watch error while trying to watch dir "foo".
		if err := <-watchErrs; err == nil {
			t.Errorf("did not capture watch registration failure for dir foo")
		}

		// The file watcher should retry watch registration and eventually succeed
		// watching for all dir under 'foo' after the file got created.
		{
			if err := os.WriteFile(to, []byte("package main"), 0644); err != nil {
				t.Errorf("fail to write file %v", err)
			}

			timer := time.NewTimer(30 * time.Second)
			defer timer.Stop()

		outer:
			for {
				select {
				case _, ok := <-watchErrs:
					if !ok {
						break outer
					}
				case <-timer.C:
					t.Errorf("timed out after 30s waiting for watches on foo to be established")
				}
			}
		}

		// Once the watch registration is done, file events under the
		// dir "foo" should be captured
		if err := os.WriteFile(filepath.Join(root, "foo", "new.go"), []byte("package main"), 0644); err != nil {
			t.Fatalf("fail to write file %v", err)
		}
	}

	select {
	case <-foundAll:
	case <-time.After(30 * time.Second):
		if matched != len(wants) {
			var want strings.Builder
			for _, e := range wants {
				want.WriteString(fmt.Sprintf("URI: %s type: %v\n", e.URI, e.Type))
			}
			var got strings.Builder
			for _, e := range gots {
				got.WriteString(fmt.Sprintf("URI: %s type: %v\n", strings.TrimPrefix(e.URI.Path(), root+"/"), e.Type))
			}
			t.Errorf("found %v matching events slice\nwant sequences:\n%s\nall got:\n%s", matched, want.String(), got.String())
		}

	}
}

func TestStress(t *testing.T) {
	switch runtime.GOOS {
	case "darwin", "linux", "windows":
	default:
		t.Skip("unsupported OS")
	}

	const (
		delay       = 50 * time.Millisecond
		parallelism = 100 // number of parallel instances of each kind of operation
	)

	root := t.TempDir()

	mkdir := func(base string) func() error {
		return func() error {
			return os.Mkdir(filepath.Join(root, base), 0755)
		}
	}
	write := func(base string) func() error {
		return func() error {
			return os.WriteFile(filepath.Join(root, base), []byte("package main"), 0644)
		}
	}
	remove := func(base string) func() error {
		return func() error {
			return os.Remove(filepath.Join(root, base))
		}
	}
	rename := func(old, new string) func() error {
		return func() error {
			return os.Rename(filepath.Join(root, old), filepath.Join(root, new))
		}
	}

	wants := make(map[protocol.FileEvent]bool)
	want := func(base string, t protocol.FileChangeType) {
		wants[protocol.FileEvent{URI: protocol.URIFromPath(filepath.Join(root, base)), Type: t}] = true
	}

	for i := range parallelism {
		// Create files and dirs that will be deleted or renamed later.
		if err := cmp.Or(
			mkdir(fmt.Sprintf("delete-dir-%d", i))(),
			mkdir(fmt.Sprintf("old-dir-%d", i))(),
			write(fmt.Sprintf("delete-file-%d.go", i))(),
			write(fmt.Sprintf("old-file-%d.go", i))(),
		); err != nil {
			t.Fatal(err)
		}

		// Add expected notification events to the "wants" set.
		want(fmt.Sprintf("file-%d.go", i), protocol.Created)
		want(fmt.Sprintf("delete-file-%d.go", i), protocol.Deleted)
		want(fmt.Sprintf("old-file-%d.go", i), protocol.Deleted)
		want(fmt.Sprintf("new-file-%d.go", i), protocol.Created)
		want(fmt.Sprintf("dir-%d", i), protocol.Created)
		want(fmt.Sprintf("delete-dir-%d", i), protocol.Deleted)
		want(fmt.Sprintf("old-dir-%d", i), protocol.Deleted)
		want(fmt.Sprintf("new-dir-%d", i), protocol.Created)
	}

	foundAll := make(chan struct{})

	eventsHandler := func(events []protocol.FileEvent) {
		if len(wants) == 0 { // avoid closing twice
			return
		}
		for _, e := range events {
			delete(wants, e)
		}
		if len(wants) == 0 {
			close(foundAll)
		}
	}
	errHandler := func(err error) {
		t.Errorf("error from watcher: %v", err)
	}
	w, err := filewatcher.New("fsnotify", delay, nil, eventsHandler, errHandler)
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := w.Close(); err != nil {
			t.Errorf("failed to close the file watcher: %v", err)
		}
	}()

	if err := w.WatchDir(root); err != nil {
		t.Fatal(err)
	}

	// Spin up multiple goroutines, to perform 6 file system operations i.e.
	// create, delete, rename of file or directory. For deletion and rename,
	// the goroutine deletes / renames files or directories created before the
	// watcher starts.
	var g errgroup.Group
	for id := range parallelism {
		ops := []func() error{
			write(fmt.Sprintf("file-%d.go", id)),
			remove(fmt.Sprintf("delete-file-%d.go", id)),
			rename(fmt.Sprintf("old-file-%d.go", id), fmt.Sprintf("new-file-%d.go", id)),
			mkdir(fmt.Sprintf("dir-%d", id)),
			remove(fmt.Sprintf("delete-dir-%d", id)),
			rename(fmt.Sprintf("old-dir-%d", id), fmt.Sprintf("new-dir-%d", id)),
		}
		for _, f := range ops {
			g.Go(f)
		}
	}
	if err := g.Wait(); err != nil {
		t.Fatal(err)
	}

	select {
	case <-foundAll:
	case <-time.After(30 * time.Second):
		if len(wants) > 0 {
			t.Errorf("missing expected events: %#v", moremaps.KeySlice(wants))
		}
	}
}


================================================
FILE: gopls/internal/filewatcher/fsnotify_watcher.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package filewatcher

import (
	"errors"
	"io/fs"
	"log"
	"log/slog"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"time"

	"github.com/fsnotify/fsnotify"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/robustio"
)

// ErrClosed is used when trying to operate on a closed Watcher.
var ErrClosed = errors.New("file watcher: watcher already closed")

// fsnotifyWatcher collects events from a [fsnotify.Watcher] and converts them
// into batched LSP [protocol.FileEvent]s.
type fsnotifyWatcher struct {
	logger *slog.Logger

	stop chan struct{}  // closed by Close to terminate run and process loop
	wg   sync.WaitGroup // counts the number of active run and process goroutines (max 2)

	ready chan struct{} // signals work to process

	watcher *fsnotify.Watcher

	mu sync.Mutex // guards all fields below

	// in is the queue of fsnotify events waiting to be processed.
	in []fsnotify.Event

	// out is the current batch of unsent file events, which will be sent when
	// the timer expires.
	out []protocol.FileEvent

	// knownDirs tracks all known directories to help distinguish between file
	// and directory deletion events.
	knownDirs map[string]struct{}
}

// New creates a new file watcher and starts its event-handling loop. The
// [Watcher.Close] method must be called to clean up resources.
//
// The provided event handler is called sequentially with a batch of file events,
// but the error handler is called concurrently. The watcher blocks until the
// handler returns, so the handlers should be fast and non-blocking.
func NewFSNotifyWatcher(delay time.Duration, logger *slog.Logger, eventsHandler func([]protocol.FileEvent), errHandler func(error)) (Watcher, error) {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		return nil, err
	}
	w := &fsnotifyWatcher{
		logger:    logger,
		watcher:   watcher,
		knownDirs: make(map[string]struct{}),
		stop:      make(chan struct{}),
		ready:     make(chan struct{}, 1),
	}

	w.wg.Add(1)
	go w.run(eventsHandler, errHandler, delay)

	w.wg.Add(1)
	go w.process(errHandler)

	return w, nil
}

// run is the receiver and sender loop.
//
// As receiver, its primary responsibility is to drain events and errors from
// the fsnotify watcher as quickly as possible and enqueue events for processing
// by the process goroutine. This is critical to work around a potential
// fsnotify deadlock (see fsnotify/fsnotify#502).
//
// As sender, it manages a timer and flush events to the handler if there is
// no events captured for a period of time.
func (w *fsnotifyWatcher) run(eventsHandler func([]protocol.FileEvent), errHandler func(error), delay time.Duration) {
	defer w.wg.Done()

	timer := time.NewTimer(delay)
	defer timer.Stop()

	for {
		select {
		case <-w.stop:
			return

		case <-timer.C:
			// TODO(hxjiang): flush is triggered when there is no events captured
			// in a certain period of time, it may be better to flush it when the
			// w.in is completely empty.
			//
			// Currently, partial events may be emitted if a directory watch gets
			// stuck. While this does not affect correctness, it means events
			// might be sent to the client in multiple portions rather than a
			// single batch.
			w.mu.Lock()
			events := w.out
			w.out = nil
			w.mu.Unlock()

			if len(events) > 0 {
				eventsHandler(events)
			}

			timer.Reset(delay)

		case event, ok := <-w.watcher.Events:
			// The watcher closed. Continue the loop and let the <-w.stop case
			// handle the actual shutdown.
			if !ok {
				continue
			}

			// TODO(hxjiang): perform some filtering before we reset the timer
			// to avoid consistently resetting the timer in a noisy file system,
			// or simply convert the event here.
			timer.Reset(delay)

			w.mu.Lock()
			w.in = append(w.in, event)
			w.mu.Unlock()

			w.signal()

		case err, ok := <-w.watcher.Errors:
			// The watcher closed. Continue the loop and let the <-w.stop case
			// handle the actual shutdown.
			if !ok {
				continue
			}

			errHandler(err)
		}
	}
}

// process is a worker goroutine that converts raw fsnotify events from queue
// and handles the potentially blocking work of watching new directories. It is
// the counterpart to the run goroutine.
func (w *fsnotifyWatcher) process(errHandler func(error)) {
	defer w.wg.Done()

	for {
		select {
		case <-w.stop:
			return

		case <-w.ready:
			w.mu.Lock()
			events := w.in
			w.in = nil
			w.mu.Unlock()

			for _, event := range events {
				// File watcher is closing, drop any remaining work.
				select {
				case <-w.stop:
					return
				default:
				}

				// fsnotify does not guarantee clean filepaths.
				event.Name = filepath.Clean(event.Name)

				// fsnotify.Event should not be handled concurrently, to preserve their
				// original order. For example, if a file is deleted and recreated,
				// concurrent handling could process the events in reverse order.
				e, isDir := w.convertEvent(event)
				if e == (protocol.FileEvent{}) {
					continue
				}

				var synthesized []protocol.FileEvent // synthesized create events

				if isDir {
					switch e.Type {
					case protocol.Created:
						// Walks the entire directory tree, synthesizes create
						// events for its contents, and establishes watches for
						// subdirectories. This recursive, pre-order traversal
						// guarantees a logical event sequence: parent directory
						// creation events always precede those of their children.
						//
						// For example, consider a creation event for directory
						// a, and suppose a has contents [a/b, a/b/c, a/c, a/c/d].
						// The effective events will be:
						//
						//     CREATE a
						//     CREATE a/b
						//     CREATE a/b/c
						//     CREATE a/c
						//     CREATE a/c/d
						w.walkDirWithRetry(event.Name, errHandler, func(path string, isDir bool) error {
							if path != event.Name {
								synthesized = append(synthesized, protocol.FileEvent{
									URI:  protocol.URIFromPath(path),
									Type: protocol.Created,
								})
							}

							if isDir {
								return w.watchDir(path)
							} else {
								return nil
							}
						})

					case protocol.Deleted:
						// Upon removal, we only need to remove the entries from
						// the map. The [fsnotify.Watcher] removes the watch for
						// us. fsnotify/fsnotify#268
						w.mu.Lock()
						delete(w.knownDirs, event.Name)
						w.mu.Unlock()
					default:
						// convertEvent enforces that dirs are only Created or Deleted.
						panic("impossible")
					}
				}

				// Discovered events must be appended to the 'out' slice atomically.
				// This ensures that at any point, the slice contains a logically
				// correct (maybe slightly outdated) batch of file events that is
				// ready to be flushed.
				w.mu.Lock()
				// Some systems emit duplicate change events in close
				// succession upon file modification. While the current
				// deduplication is naive and only handles immediate duplicates,
				// a more robust solution is needed.
				// https://github.com/fsnotify/fsnotify?tab=readme-ov-file#why-do-i-get-many-chmod-events
				//
				// TODO(hxjiang): Enhance deduplication. The current batching of
				// events means all duplicates, regardless of proximity, should
				// be removed. Consider checking the entire buffered slice or
				// using a map for this.
				if len(w.out) == 0 || w.out[len(w.out)-1] != e {
					w.out = append(w.out, e)
				}
				w.out = append(w.out, synthesized...) // synthesized events are guaranteed to be unique
				w.mu.Unlock()
			}
		}
	}
}

// signal notifies the process goroutine that events are added to the queue and
// ready for handling.
func (w *fsnotifyWatcher) signal() {
	select {
	case w.ready <- struct{}{}:
	default:
	}
}

// skipDir reports whether the input dir should be skipped.
// Directories that are unlikely to contain Go source files relevant for
// analysis, such as .git directories or testdata, should be skipped to
// avoid unnecessary file system notifications. This reduces noise and
// improves efficiency. Conversely, any directory that might contain Go
// source code should be watched to ensure that gopls can respond to
// file changes.
func skipDir(dirName string) bool {
	// TODO(hxjiang): the file watcher should honor gopls directory
	// filter or the new go.mod ignore directive, or actively listening
	// to gopls register capability request with method
	// "workspace/didChangeWatchedFiles" like a real LSP client.
	return strings.HasPrefix(dirName, ".") || strings.HasPrefix(dirName, "_") || dirName == "testdata"
}

// skipFile reports whether the file should be skipped.
func skipFile(fileName string) bool {
	switch strings.TrimPrefix(filepath.Ext(fileName), ".") {
	case "go", "mod", "sum", "work", "s":
		return false
	default:
		return true
	}
}

// WatchDir walks through the directory and all its subdirectories, adding
// them to the watcher.
func (w *fsnotifyWatcher) WatchDir(path string) error {
	log.Printf("Watching %s", path)
	return filepath.WalkDir(filepath.Clean(path), func(path string, d fs.DirEntry, err error) error {
		if d.IsDir() {
			if skipDir(d.Name()) {
				return filepath.SkipDir
			}

			return w.watchDir(path)
		}
		return nil
	})
}

// convertEvent translates an [fsnotify.Event] into a [protocol.FileEvent].
// It returns the translated event and a boolean indicating if the path was a
// directory. For directories, the event Type is either Created or Deleted.
// It returns empty event for events that should be ignored.
func (w *fsnotifyWatcher) convertEvent(event fsnotify.Event) (_ protocol.FileEvent, isDir bool) {
	// Determine if the event is for a directory.
	if info, err := os.Stat(event.Name); err == nil {
		isDir = info.IsDir()
	} else if os.IsNotExist(err) {
		// Upon deletion, the file/dir has been removed. fsnotify does not
		// provide information regarding the deleted item.
		// Use the set of known directories to determine if the deleted item was a directory.
		isDir = w.isWatchedDir(event.Name)
	} else {
		// If statting failed, something is wrong with the file system.
		// Log and move on.
		if w.logger != nil {
			w.logger.Error("failed to stat path, skipping event as its type (file/dir) is unknown", "path", event.Name, "err", err)
		}
		return protocol.FileEvent{}, false
	}

	// Filter out events for directories and files that are not of interest.
	if isDir && skipDir(filepath.Base(event.Name)) {
		return protocol.FileEvent{}, true
	}
	if !isDir && skipFile(filepath.Base(event.Name)) {
		return protocol.FileEvent{}, false
	}

	var t protocol.FileChangeType
	switch {
	case event.Op.Has(fsnotify.Rename):
		// A rename is treated as a deletion of the old path because the
		// fsnotify RENAME event doesn't include the new path. A separate
		// CREATE event will be sent for the new path if the destination
		// directory is watched.
		fallthrough
	case event.Op.Has(fsnotify.Remove):
		// TODO(hxjiang): Directory removal events from some LSP clients may
		// not include corresponding removal events for child files and
		// subdirectories. Should we do some filtering when adding the dir
		// deletion event to the events slice.
		t = protocol.Deleted
	case event.Op.Has(fsnotify.Create):
		t = protocol.Created
	case event.Op.Has(fsnotify.Write):
		if isDir {
			return protocol.FileEvent{}, isDir // ignore dir write events
		}
		t = protocol.Changed
	default:
		return protocol.FileEvent{}, isDir // ignore the rest of the events
	}

	return protocol.FileEvent{
		URI:  protocol.URIFromPath(event.Name),
		Type: t,
	}, isDir
}

// watchDir registers a watch for a directory, retrying with backoff if it fails.
//
// Returns nil on success or watcher closing; otherwise, the last error after
// all retries.
func (w *fsnotifyWatcher) watchDir(path string) error {
	w.mu.Lock()
	w.knownDirs[path] = struct{}{}
	w.mu.Unlock()

	// On darwin, watching a directory will fail if it contains broken symbolic
	// links. This state can occur temporarily during operations like a git
	// branch switch. To handle this, we retry multiple times with exponential
	// backoff, allowing time for the symbolic link's target to be created.
	var (
		delay = 500 * time.Millisecond
		err   error
	)

	for i := range 5 {
		if i > 0 {
			select {
			case <-time.After(delay):
				delay *= 2
			case <-w.stop:
				return nil
			}
		}
		// This function may block due to fsnotify/fsnotify#502.
		err = w.watcher.Add(path)
		if afterAddHook != nil {
			afterAddHook(path, err)
		}
		if err == nil {
			break
		}
	}

	return err
}

var afterAddHook func(path string, err error)

// isWatchedDir reports whether the given path is a known directory that
// the watcher is managing.
func (w *fsnotifyWatcher) isWatchedDir(path string) bool {
	w.mu.Lock()
	defer w.mu.Unlock()

	_, isDir := w.knownDirs[path]
	return isDir
}

// Poke is a no-op for fsnotify watcher, as it relies on OS events.
func (w *fsnotifyWatcher) Poke() {}

// Close shuts down the watcher, waits for the internal goroutine to terminate,
// and returns any final error.
func (w *fsnotifyWatcher) Close() error {
	// Wait for fsnotify' watcher to terminate.
	err := w.watcher.Close()

	// Wait for run and process loop to terminate. It's important to stop the
	// run and process loop the last place because we don't know whether
	// fsnotify's watcher expect us to keep consuming events or errors from
	// [fsnotify.Watcher.Events] and [fsnotify.Watcher.Errors] while it's being
	// closed.
	// To avoid any potential deadlock, have the channel receiver running until
	// the last minute.
	close(w.stop)
	w.wg.Wait()

	return err
}

// walkDir calls fn against current path and recursively descends path for each
// file or directory of our interest.
func (w *fsnotifyWatcher) walkDir(path string, isDir bool, errHandler func(error), fn func(path string, isDir bool) error) {
	if err := fn(path, isDir); err != nil {
		errHandler(err)
		return
	}

	if !isDir {
		return
	}

	entries, err := tryFSOperation(w.stop, func() ([]fs.DirEntry, error) {
		// ReadDir may fail due because other processes may be actively
		// modifying the watched dir see golang/go#74820.
		// TODO(hxjiang): consider adding robustio.ReadDir.
		return os.ReadDir(path)
	})
	if err != nil {
		if err != ErrClosed {
			errHandler(err)
		}
		return
	}

	for _, e := range entries {
		if e.IsDir() && skipDir(e.Name()) {
			continue
		}
		if !e.IsDir() && skipFile(e.Name()) {
			continue
		}

		w.walkDir(filepath.Join(path, e.Name()), e.IsDir(), errHandler, fn)
	}
}

// walkDirWithRetry walks the file tree rooted at root, calling fn for each
// file or directory of our interest in the tree, including root.
//
// All errors that arise visiting directories or files will be reported to the
// provided error handler function. If an error is encountered visiting a
// directory, that entire subtree will be skipped.
//
// walkDirWithRetry does not follow symbolic links.
//
// It is used instead of [filepath.WalkDir] because it provides control over
// retry behavior when reading a directory fails. If [os.ReadDir] fails with an
// ephemeral error, it is retried multiple times with exponential backoff.
//
// TODO(hxjiang): call walkDirWithRetry in WalkDir.
func (w *fsnotifyWatcher) walkDirWithRetry(root string, errHandler func(error), fn func(path string, isDir bool) error) {
	info, err := tryFSOperation(w.stop, func() (os.FileInfo, error) {
		return os.Lstat(root) // [os.Lstat] does not follow symlink.
	})
	if err != nil {
		if err != ErrClosed {
			errHandler(err)
		}
		return
	}

	w.walkDir(root, info.IsDir(), errHandler, fn)
}

// tryFSOperation executes a function `op` with retry logic, making it resilient
// to transient errors. It attempts the operation up to 5 times with exponential
// backoff. Retries occur only if the error is ephemeral.
//
// The operation can be interrupted by closing the `stop` channel, in which case
// it returns [ErrClosed].
func tryFSOperation[Result any](stop <-chan struct{}, op func() (Result, error)) (Result, error) {
	var (
		delay = 50 * time.Millisecond
		err   error
	)

	for i := range 5 {
		if i > 0 {
			select {
			case <-time.After(delay):
				delay *= 2
			case <-stop:
				var zero Result
				return zero, ErrClosed
			}
		}

		var res Result
		res, err = op()

		if robustio.IsEphemeralError(err) {
			continue
		} else {
			return res, err
		}
	}

	var zero Result
	return zero, err // return last error encountered
}


================================================
FILE: gopls/internal/fuzzy/input.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuzzy

import (
	"unicode"
)

// RuneRole specifies the role of a rune in the context of an input.
type RuneRole byte

const (
	// RNone specifies a rune without any role in the input (i.e., whitespace/non-ASCII).
	RNone RuneRole = iota
	// RSep specifies a rune with the role of segment separator.
	RSep
	// RTail specifies a rune which is a lower-case tail in a word in the input.
	RTail
	// RUCTail specifies a rune which is an upper-case tail in a word in the input.
	RUCTail
	// RHead specifies a rune which is the first character in a word in the input.
	RHead
)

// RuneRoles detects the roles of each byte rune in an input string and stores it in the output
// slice. The rune role depends on the input type. Stops when it parsed all the runes in the string
// or when it filled the output. If output is nil, then it gets created.
func RuneRoles(candidate []byte, reuse []RuneRole) []RuneRole {
	var output []RuneRole
	if cap(reuse) < len(candidate) {
		output = make([]RuneRole, 0, len(candidate))
	} else {
		output = reuse[:0]
	}

	prev, prev2 := rtNone, rtNone
	for i := range candidate {
		r := rune(candidate[i])

		role := RNone

		curr := rtLower
		if candidate[i] <= unicode.MaxASCII {
			curr = runeType(rt[candidate[i]] - '0')
		}

		if curr == rtLower {
			if prev == rtNone || prev == rtPunct {
				role = RHead
			} else {
				role = RTail
			}
		} else if curr == rtUpper {
			role = RHead

			if prev == rtUpper {
				// This and previous characters are both upper case.

				if i+1 == len(candidate) {
					// This is last character, previous was also uppercase -> this is UCTail
					// i.e., (current char is C): aBC / BC / ABC
					role = RUCTail
				}
			}
		} else if curr == rtPunct {
			switch r {
			case '.', ':':
				role = RSep
			}
		}
		if curr != rtLower {
			if i > 1 && output[i-1] == RHead && prev2 == rtUpper && (output[i-2] == RHead || output[i-2] == RUCTail) {
				// The previous two characters were uppercase. The current one is not a lower case, so the
				// previous one can't be a HEAD. Make it a UCTail.
				// i.e., (last char is current char - B must be a UCTail): ABC / ZABC / AB.
				output[i-1] = RUCTail
			}
		}

		output = append(output, role)
		prev2 = prev
		prev = curr
	}
	return output
}

type runeType byte

const (
	rtNone runeType = iota
	rtPunct
	rtLower
	rtUpper
)

const rt = "00000000000000000000000000000000000000000000001122222222221000000333333333333333333333333330000002222222222222222222222222200000"

// LastSegment returns the substring representing the last segment from the input, where each
// byte has an associated RuneRole in the roles slice. This makes sense only for inputs of Symbol
// or Filename type.
func LastSegment(input string, roles []RuneRole) string {
	// Exclude ending separators.
	end := len(input) - 1
	for end >= 0 && roles[end] == RSep {
		end--
	}
	if end < 0 {
		return ""
	}

	start := end - 1
	for start >= 0 && roles[start] != RSep {
		start--
	}

	return input[start+1 : end+1]
}

// fromChunks copies string chunks into the given buffer.
func fromChunks(chunks []string, buffer []byte) []byte {
	ii := 0
	for _, chunk := range chunks {
		for i := range len(chunk) {
			if ii >= cap(buffer) {
				break
			}
			buffer[ii] = chunk[i]
			ii++
		}
	}
	return buffer[:ii]
}

// toLower transforms the input string to lower case, which is stored in the output byte slice.
// The lower casing considers only ASCII values - non ASCII values are left unmodified.
// Stops when parsed all input or when it filled the output slice. If output is nil, then it gets
// created.
func toLower(input []byte, reuse []byte) []byte {
	output := reuse
	if cap(reuse) < len(input) {
		output = make([]byte, len(input))
	}

	for i := range input {
		r := rune(input[i])
		if input[i] <= unicode.MaxASCII {
			if 'A' <= r && r <= 'Z' {
				r += 'a' - 'A'
			}
		}
		output[i] = byte(r)
	}
	return output[:len(input)]
}

// WordConsumer defines a consumer for a word delimited by the [start,end) byte offsets in an input
// (start is inclusive, end is exclusive).
type WordConsumer func(start, end int)

// Words find word delimiters in an input based on its bytes' mappings to rune roles. The offset
// delimiters for each word are fed to the provided consumer function.
func Words(roles []RuneRole, consume WordConsumer) {
	var wordStart int
	for i, r := range roles {
		switch r {
		case RUCTail, RTail:
		case RHead, RNone, RSep:
			if i != wordStart {
				consume(wordStart, i)
			}
			wordStart = i
			if r != RHead {
				// Skip this character.
				wordStart = i + 1
			}
		}
	}
	if wordStart != len(roles) {
		consume(wordStart, len(roles))
	}
}


================================================
FILE: gopls/internal/fuzzy/input_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuzzy_test

import (
	"bytes"
	"slices"
	"sort"
	"testing"

	"golang.org/x/tools/gopls/internal/fuzzy"
)

var rolesTests = []struct {
	str  string
	want string
}{
	{str: "abc::def::goo", want: "Ccc//Ccc//Ccc"},
	{str: "proto::Message", want: "Ccccc//Ccccccc"},
	{str: "AbstractSWTFactory", want: "CcccccccCuuCcccccc"},
	{str: "Abs012", want: "Cccccc"},
	{str: "/", want: " "},
	{str: "fOO", want: "CCu"},
	{str: "fo_oo.o_oo", want: "Cc Cc/C Cc"},
}

func rolesString(roles []fuzzy.RuneRole) string {
	var buf bytes.Buffer
	for _, r := range roles {
		buf.WriteByte(" /cuC"[int(r)])
	}
	return buf.String()
}

func TestRoles(t *testing.T) {
	for _, tc := range rolesTests {
		gotRoles := make([]fuzzy.RuneRole, len(tc.str))
		fuzzy.RuneRoles([]byte(tc.str), gotRoles)
		got := rolesString(gotRoles)
		if got != tc.want {
			t.Errorf("roles(%s) = %v; want %v", tc.str, got, tc.want)
		}
	}
}

var wordSplitTests = []struct {
	input string
	want  []string
}{
	{
		input: "foo bar baz",
		want:  []string{"foo", "bar", "baz"},
	},
	{
		input: "fooBarBaz",
		want:  []string{"foo", "Bar", "Baz"},
	},
	{
		input: "FOOBarBAZ",
		want:  []string{"FOO", "Bar", "BAZ"},
	},
	{
		input: "foo123_bar2Baz3",
		want:  []string{"foo123", "bar2", "Baz3"},
	},
}

func TestWordSplit(t *testing.T) {
	for _, tc := range wordSplitTests {
		roles := fuzzy.RuneRoles([]byte(tc.input), nil)

		var got []string
		consumer := func(i, j int) {
			got = append(got, tc.input[i:j])
		}
		fuzzy.Words(roles, consumer)

		if eq := diffStringLists(tc.want, got); !eq {
			t.Errorf("input %v: (want %v -> got %v)", tc.input, tc.want, got)
		}
	}
}

func diffStringLists(a, b []string) bool {
	sort.Strings(a)
	sort.Strings(b)
	return slices.Equal(a, b)
}

var lastSegmentSplitTests = []struct {
	str  string
	want string
}{
	{
		str:  "identifier",
		want: "identifier",
	},
	{
		str:  "two_words",
		want: "two_words",
	},
	{
		str:  "first::second",
		want: "second",
	},
	{
		str:  "foo.bar.FOOBar_buz123_test",
		want: "FOOBar_buz123_test",
	},
}

func TestLastSegment(t *testing.T) {
	for _, tc := range lastSegmentSplitTests {
		roles := fuzzy.RuneRoles([]byte(tc.str), nil)

		got := fuzzy.LastSegment(tc.str, roles)

		if got != tc.want {
			t.Errorf("str %v: want %v; got %v", tc.str, tc.want, got)
		}
	}
}

func BenchmarkRoles(b *testing.B) {
	str := "AbstractSWTFactory"
	out := make([]fuzzy.RuneRole, len(str))

	for b.Loop() {
		fuzzy.RuneRoles([]byte(str), out)
	}
	b.SetBytes(int64(len(str)))
}


================================================
FILE: gopls/internal/fuzzy/matcher.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fuzzy implements a fuzzy matching algorithm.
package fuzzy

import (
	"bytes"
	"fmt"
)

const (
	// MaxInputSize is the maximum size of the input scored against the fuzzy matcher. Longer inputs
	// will be truncated to this size.
	MaxInputSize = 127
	// MaxPatternSize is the maximum size of the pattern used to construct the fuzzy matcher. Longer
	// inputs are truncated to this size.
	MaxPatternSize = 63
)

type scoreVal int

func (s scoreVal) val() int {
	return int(s) >> 1
}

func (s scoreVal) prevK() int {
	return int(s) & 1
}

func score(val int, prevK int /*0 or 1*/) scoreVal {
	return scoreVal(val<<1 + prevK)
}

// Matcher implements a fuzzy matching algorithm for scoring candidates against a pattern.
// The matcher does not support parallel usage.
type Matcher struct {
	pattern       string
	patternLower  []byte // lower-case version of the pattern
	patternShort  []byte // first characters of the pattern
	caseSensitive bool   // set if the pattern is mix-cased

	patternRoles []RuneRole // the role of each character in the pattern
	roles        []RuneRole // the role of each character in the tested string

	scores [MaxInputSize + 1][MaxPatternSize + 1][2]scoreVal

	scoreScale float32

	lastCandidateLen     int // in bytes
	lastCandidateMatched bool

	// Reusable buffers to avoid allocating for every candidate.
	//  - inputBuf stores the concatenated input chunks
	//  - lowerBuf stores the last candidate in lower-case
	//  - rolesBuf stores the calculated roles for each rune in the last
	//    candidate.
	inputBuf [MaxInputSize]byte
	lowerBuf [MaxInputSize]byte
	rolesBuf [MaxInputSize]RuneRole
}

func (m *Matcher) String() string { return m.pattern }

func (m *Matcher) bestK(i, j int) int {
	if m.scores[i][j][0].val() < m.scores[i][j][1].val() {
		return 1
	}
	return 0
}

// NewMatcher returns a new fuzzy matcher for scoring candidates against the provided pattern.
func NewMatcher(pattern string) *Matcher {
	if len(pattern) > MaxPatternSize {
		pattern = pattern[:MaxPatternSize]
	}

	m := &Matcher{
		pattern:      pattern,
		patternLower: toLower([]byte(pattern), nil),
	}

	for i, c := range m.patternLower {
		if pattern[i] != c {
			m.caseSensitive = true
			break
		}
	}

	if len(pattern) > 3 {
		m.patternShort = m.patternLower[:3]
	} else {
		m.patternShort = m.patternLower
	}

	m.patternRoles = RuneRoles([]byte(pattern), nil)

	if len(pattern) > 0 {
		maxCharScore := 4
		m.scoreScale = 1 / float32(maxCharScore*len(pattern))
	}

	return m
}

// Score returns the score returned by matching the candidate to the pattern.
// This is not designed for parallel use. Multiple candidates must be scored sequentially.
// Returns a score between 0 and 1 (0 - no match, 1 - perfect match).
func (m *Matcher) Score(candidate string) float32 {
	return m.ScoreChunks([]string{candidate})
}

func (m *Matcher) ScoreChunks(chunks []string) float32 {
	candidate := fromChunks(chunks, m.inputBuf[:])
	if len(candidate) > MaxInputSize {
		candidate = candidate[:MaxInputSize]
	}
	lower := toLower(candidate, m.lowerBuf[:])
	m.lastCandidateLen = len(candidate)

	if len(m.pattern) == 0 {
		// Empty patterns perfectly match candidates.
		return 1
	}

	if m.match(candidate, lower) {
		sc := m.computeScore(candidate, lower)
		if sc > minScore/2 && !m.poorMatch() {
			m.lastCandidateMatched = true
			if len(m.pattern) == len(candidate) {
				// Perfect match.
				return 1
			}

			if sc < 0 {
				sc = 0
			}
			normalizedScore := min(float32(sc)*m.scoreScale, 1)

			return normalizedScore
		}
	}

	m.lastCandidateMatched = false
	return 0
}

const minScore = -10000

// MatchedRanges returns matches ranges for the last scored string as a flattened array of
// [begin, end) byte offset pairs.
func (m *Matcher) MatchedRanges() []int {
	if len(m.pattern) == 0 || !m.lastCandidateMatched {
		return nil
	}
	i, j := m.lastCandidateLen, len(m.pattern)
	if m.scores[i][j][0].val() < minScore/2 && m.scores[i][j][1].val() < minScore/2 {
		return nil
	}

	var ret []int
	k := m.bestK(i, j)
	for i > 0 {
		take := (k == 1)
		k = m.scores[i][j][k].prevK()
		if take {
			if len(ret) == 0 || ret[len(ret)-1] != i {
				ret = append(ret, i)
				ret = append(ret, i-1)
			} else {
				ret[len(ret)-1] = i - 1
			}
			j--
		}
		i--
	}
	// Reverse slice.
	for i := range len(ret) / 2 {
		ret[i], ret[len(ret)-1-i] = ret[len(ret)-1-i], ret[i]
	}
	return ret
}

func (m *Matcher) match(candidate []byte, candidateLower []byte) bool {
	i, j := 0, 0
	for ; i < len(candidateLower) && j < len(m.patternLower); i++ {
		if candidateLower[i] == m.patternLower[j] {
			j++
		}
	}
	if j != len(m.patternLower) {
		return false
	}

	// The input passes the simple test against pattern, so it is time to classify its characters.
	// Character roles are used below to find the last segment.
	m.roles = RuneRoles(candidate, m.rolesBuf[:])

	return true
}

func (m *Matcher) computeScore(candidate []byte, candidateLower []byte) int {
	pattLen, candLen := len(m.pattern), len(candidate)

	for j := 0; j <= len(m.pattern); j++ {
		m.scores[0][j][0] = minScore << 1
		m.scores[0][j][1] = minScore << 1
	}
	m.scores[0][0][0] = score(0, 0) // Start with 0.

	segmentsLeft, lastSegStart := 1, 0
	for i := range candLen {
		if m.roles[i] == RSep {
			segmentsLeft++
			lastSegStart = i + 1
		}
	}

	// A per-character bonus for a consecutive match.
	consecutiveBonus := 2
	wordIdx := 0 // Word count within segment.
	for i := 1; i <= candLen; i++ {

		role := m.roles[i-1]
		isHead := role == RHead

		if isHead {
			wordIdx++
		} else if role == RSep && segmentsLeft > 1 {
			wordIdx = 0
			segmentsLeft--
		}

		var skipPenalty int
		if i == 1 || (i-1) == lastSegStart {
			// Skipping the start of first or last segment.
			skipPenalty++
		}

		for j := 0; j <= pattLen; j++ {
			// By default, we don't have a match. Fill in the skip data.
			m.scores[i][j][1] = minScore << 1

			// Compute the skip score.
			k := 0
			if m.scores[i-1][j][0].val() < m.scores[i-1][j][1].val() {
				k = 1
			}

			skipScore := m.scores[i-1][j][k].val()
			// Do not penalize missing characters after the last matched segment.
			if j != pattLen {
				skipScore -= skipPenalty
			}
			m.scores[i][j][0] = score(skipScore, k)

			if j == 0 || candidateLower[i-1] != m.patternLower[j-1] {
				// Not a match.
				continue
			}
			pRole := m.patternRoles[j-1]

			if role == RTail && pRole == RHead {
				if j > 1 {
					// Not a match: a head in the pattern matches a tail character in the candidate.
					continue
				}
				// Special treatment for the first character of the pattern. We allow
				// matches in the middle of a word if they are long enough, at least
				// min(3, pattern.length) characters.
				if !bytes.HasPrefix(candidateLower[i-1:], m.patternShort) {
					continue
				}
			}

			// Compute the char score.
			var charScore int
			// Bonus: the char is in the candidate's last segment.
			if segmentsLeft <= 1 {
				charScore++
			}

			// Bonus: exact case match between pattern and candidate.
			if candidate[i-1] == m.pattern[j-1] ||
				// Bonus: candidate char is a head and pattern is all
				// lowercase. There is no segmentation in an all lowercase
				// pattern, so assume any char in pattern can be a head. Note
				// that we are intentionally _not_ giving a bonus to a case
				// insensitive match when the pattern is case sensitive.
				role == RHead && !m.caseSensitive {
				charScore++
			}

			// Penalty: pattern char is Head, candidate char is Tail.
			if role == RTail && pRole == RHead {
				charScore--
			}
			// Penalty: first pattern character matched in the middle of a word.
			if j == 1 && role == RTail {
				charScore -= 4
			}

			// Third dimension encodes whether there is a gap between the previous match and the current
			// one.
			for k := range 2 {
				sc := m.scores[i-1][j-1][k].val() + charScore

				isConsecutive := k == 1 || i-1 == 0 || i-1 == lastSegStart
				if isConsecutive {
					// Bonus: a consecutive match. First character match also gets a bonus to
					// ensure prefix final match score normalizes to 1.0.
					// Logically, this is a part of charScore, but we have to compute it here because it
					// only applies for consecutive matches (k == 1).
					sc += consecutiveBonus
				}
				if k == 0 {
					// Penalty: Matching inside a segment (and previous char wasn't matched). Penalize for the lack
					// of alignment.
					if role == RTail || role == RUCTail {
						sc -= 3
					}
				}

				if sc > m.scores[i][j][1].val() {
					m.scores[i][j][1] = score(sc, k)
				}
			}
		}
	}

	result := m.scores[len(candidate)][len(m.pattern)][m.bestK(len(candidate), len(m.pattern))].val()

	return result
}

// ScoreTable returns the score table computed for the provided candidate. Used only for debugging.
func (m *Matcher) ScoreTable(candidate string) string {
	var buf bytes.Buffer

	var line1, line2, separator bytes.Buffer
	line1.WriteString("\t")
	line2.WriteString("\t")
	for j := range len(m.pattern) {
		line1.WriteString(fmt.Sprintf("%c\t\t", m.pattern[j]))
		separator.WriteString("----------------")
	}

	buf.WriteString(line1.String())
	buf.WriteString("\n")
	buf.WriteString(separator.String())
	buf.WriteString("\n")

	for i := 1; i <= len(candidate); i++ {
		line1.Reset()
		line2.Reset()

		line1.WriteString(fmt.Sprintf("%c\t", candidate[i-1]))
		line2.WriteString("\t")

		for j := 1; j <= len(m.pattern); j++ {
			line1.WriteString(fmt.Sprintf("M%6d(%c)\t", m.scores[i][j][0].val(), dir(m.scores[i][j][0].prevK())))
			line2.WriteString(fmt.Sprintf("H%6d(%c)\t", m.scores[i][j][1].val(), dir(m.scores[i][j][1].prevK())))
		}
		buf.WriteString(line1.String())
		buf.WriteString("\n")
		buf.WriteString(line2.String())
		buf.WriteString("\n")
		buf.WriteString(separator.String())
		buf.WriteString("\n")
	}

	return buf.String()
}

func dir(prevK int) rune {
	if prevK == 0 {
		return 'M'
	}
	return 'H'
}

func (m *Matcher) poorMatch() bool {
	if len(m.pattern) < 2 {
		return false
	}

	i, j := m.lastCandidateLen, len(m.pattern)
	k := m.bestK(i, j)

	var counter, len int
	for i > 0 {
		take := (k == 1)
		k = m.scores[i][j][k].prevK()
		if take {
			len++
			if k == 0 && len < 3 && m.roles[i-1] == RTail {
				// Short match in the middle of a word
				counter++
				if counter > 1 {
					return true
				}
			}
			j--
		} else {
			len = 0
		}
		i--
	}
	return false
}

// BestMatch returns the name most similar to the
// pattern, using fuzzy matching, or the empty string.
func BestMatch(pattern string, names []string) string {
	fuzz := NewMatcher(pattern)
	best := ""
	highScore := float32(0) // minimum score is 0 (no match)
	for _, name := range names {
		// TODO: Improve scoring algorithm.
		score := fuzz.Score(name)
		if score > highScore {
			highScore = score
			best = name
		} else if score == 0 {
			// Order matters in the fuzzy matching algorithm. If we find no match
			// when matching the target to the identifier, try matching the identifier
			// to the target.
			revFuzz := NewMatcher(name)
			revScore := revFuzz.Score(pattern)
			if revScore > highScore {
				highScore = revScore
				best = name
			}
		}
	}
	return best
}


================================================
FILE: gopls/internal/fuzzy/matcher_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Benchmark results:
//
// BenchmarkMatcher-12    	 1000000	      1615 ns/op	  30.95 MB/s	       0 B/op	       0 allocs/op
package fuzzy_test

import (
	"bytes"
	"fmt"
	"math"
	"testing"

	"golang.org/x/tools/gopls/internal/fuzzy"
)

type comparator struct {
	f     func(val, ref float32) bool
	descr string
}

var (
	eq = comparator{
		f: func(val, ref float32) bool {
			return val == ref
		},
		descr: "==",
	}
	ge = comparator{
		f: func(val, ref float32) bool {
			return val >= ref
		},
		descr: ">=",
	}
	gt = comparator{
		f: func(val, ref float32) bool {
			return val > ref
		},
		descr: ">",
	}
)

func (c comparator) eval(val, ref float32) bool {
	return c.f(val, ref)
}

func (c comparator) String() string {
	return c.descr
}

type scoreTest struct {
	candidate string
	comparator
	ref float32
}

var matcherTests = []struct {
	pattern string
	tests   []scoreTest
}{
	{
		pattern: "",
		tests: []scoreTest{
			{"def", eq, 1},
			{"Ab stuff c", eq, 1},
		},
	},
	{
		pattern: "abc",
		tests: []scoreTest{
			{"def", eq, 0},
			{"abd", eq, 0},
			{"abc", ge, 0},
			{"Abc", ge, 0},
			{"Ab stuff c", ge, 0},
		},
	},
	{
		pattern: "Abc",
		tests: []scoreTest{
			{"def", eq, 0},
			{"abd", eq, 0},
			{"abc", ge, 0},
			{"Abc", ge, 0},
			{"Ab stuff c", ge, 0},
		},
	},
	{
		pattern: "U",
		tests: []scoreTest{
			{"ErrUnexpectedEOF", gt, 0},
			{"ErrUnexpectedEOF.Error", eq, 0},
		},
	},
}

func TestScore(t *testing.T) {
	for _, tc := range matcherTests {
		m := fuzzy.NewMatcher(tc.pattern)
		for _, sct := range tc.tests {
			score := m.Score(sct.candidate)
			if !sct.comparator.eval(score, sct.ref) {
				t.Errorf("m.Score(%q) = %.2g, want %s %v", sct.candidate, score, sct.comparator, sct.ref)
			}
		}
	}
}

var compareCandidatesTestCases = []struct {
	pattern string
	// In `[][]string{{"foo", "bar"}, {"baz"}}`,
	// "foo" and "bar" must have same score, "baz" must be strictly higher scoring.
	orderedCandidates [][]string
}{
	{
		pattern: "Foo",
		orderedCandidates: [][]string{
			{"Barfoo"},
			{"Faoo"},
			{"F_o_o"},
			{"FaoFooa", "BarFoo"},
			{"F__oo", "F_oo"},
			{"FooA", "FooBar", "Foo"},
		},
	},
	{
		pattern: "U",
		orderedCandidates: [][]string{
			{"ErrUnexpectedEOF.Error"},
			{"ErrUnexpectedEOF"},
		},
	},
	{
		pattern: "N",
		orderedCandidates: [][]string{
			{"name"},
			{"Name"},
		},
	},
}

func TestCompareCandidateScores(t *testing.T) {
	for _, tc := range compareCandidatesTestCases {
		m := fuzzy.NewMatcher(tc.pattern)

		var prevScore float32
		var prevCandGroup []string
		for i, candGroup := range tc.orderedCandidates {
			var groupScore float32
			for j, cand := range candGroup {
				score := m.Score(cand)
				if j > 0 && score != groupScore {
					t.Fatalf("score %f of %q different than group", score, cand)
				}
				groupScore = score
			}

			if i > 0 && prevScore >= groupScore {
				t.Errorf("%s[=%v] is not scored higher than %s[=%v]", candGroup, groupScore, prevCandGroup, prevScore)
			}
			if groupScore < 0 || groupScore > 1 {
				t.Errorf("%s score is %v; want value between [0, 1]", candGroup, groupScore)
			}
			prevScore = groupScore
			prevCandGroup = candGroup
		}
	}
}

var fuzzyMatcherTestCases = []struct {
	p    string
	str  string
	want string
}{
	{p: "foo", str: "abc::foo", want: "abc::[foo]"},
	{p: "foo", str: "foo.foo", want: "foo.[foo]"},
	{p: "foo", str: "fo_oo.o_oo", want: "[fo]_oo.[o]_oo"},
	{p: "foo", str: "fo_oo.fo_oo", want: "fo_oo.[fo]_[o]o"},
	{p: "fo_o", str: "fo_oo.o_oo", want: "[f]o_oo.[o_o]o"},
	{p: "fOO", str: "fo_oo.o_oo", want: "[f]o_oo.[o]_[o]o"},
	{p: "tedit", str: "foo.TextEdit", want: "foo.[T]ext[Edit]"},
	{p: "TEdit", str: "foo.TextEdit", want: "foo.[T]ext[Edit]"},
	{p: "Tedit", str: "foo.TextEdit", want: "foo.[T]ext[Edit]"},
	{p: "Tedit", str: "foo.Textedit", want: "foo.[Te]xte[dit]"},
	{p: "TEdit", str: "foo.Textedit", want: ""},
	{p: "te", str: "foo.Textedit", want: "foo.[Te]xtedit"},
	{p: "ee", str: "foo.Textedit", want: ""}, // short middle of the word match
	{p: "ex", str: "foo.Textedit", want: "foo.T[ex]tedit"},
	{p: "exdi", str: "foo.Textedit", want: ""},  // short middle of the word match
	{p: "exdit", str: "foo.Textedit", want: ""}, // short middle of the word match
	{p: "extdit", str: "foo.Textedit", want: "foo.T[ext]e[dit]"},
	{p: "e", str: "foo.Textedit", want: "foo.T[e]xtedit"},
	{p: "E", str: "foo.Textedit", want: "foo.T[e]xtedit"},
	{p: "ed", str: "foo.Textedit", want: "foo.Text[ed]it"},
	{p: "edt", str: "foo.Textedit", want: ""}, // short middle of the word match
	{p: "edit", str: "foo.Textedit", want: "foo.Text[edit]"},
	{p: "edin", str: "foo.TexteditNum", want: "foo.Text[edi]t[N]um"},
	{p: "n", str: "node.GoNodeMax", want: "[n]ode.GoNodeMax"},
	{p: "N", str: "node.GoNodeMax", want: "[n]ode.GoNodeMax"},
	{p: "completio", str: "completion", want: "[completio]n"},
	{p: "completio", str: "completion.None", want: "[completio]n.None"},
}

func TestFuzzyMatcherRanges(t *testing.T) {
	for _, tc := range fuzzyMatcherTestCases {
		matcher := fuzzy.NewMatcher(tc.p)
		score := matcher.Score(tc.str)
		if tc.want == "" {
			if score > 0 {
				t.Errorf("Score(%s, %s) = %v; want: <= 0", tc.p, tc.str, score)
			}
			continue
		}
		if score < 0 {
			t.Errorf("Score(%s, %s) = %v, want: > 0", tc.p, tc.str, score)
			continue
		}
		got := highlightMatches(tc.str, matcher)
		if tc.want != got {
			t.Errorf("highlightMatches(%s, %s) = %v, want: %v", tc.p, tc.str, got, tc.want)
		}
	}
}

var scoreTestCases = []struct {
	p    string
	str  string
	want float64
}{
	// Score precision up to five digits. Modify if changing the score, but make sure the new values
	// are reasonable.
	{p: "abc", str: "abc", want: 1},
	{p: "abc", str: "Abc", want: 1},
	{p: "abc", str: "Abcdef", want: 1},
	{p: "strc", str: "StrCat", want: 1},
	{p: "abc_def", str: "abc_def_xyz", want: 1},
	{p: "abcdef", str: "abc_def_xyz", want: 0.91667},
	{p: "abcxyz", str: "abc_def_xyz", want: 0.91667},
	{p: "sc", str: "StrCat", want: 0.75},
	{p: "abc", str: "AbstrBasicCtor", want: 0.83333},
	{p: "foo", str: "abc::foo", want: 0.91667},
	{p: "afoo", str: "abc::foo", want: 0.9375},
	{p: "abr", str: "abc::bar", want: 0.5},
	{p: "br", str: "abc::bar", want: 0.25},
	{p: "aar", str: "abc::bar", want: 0.41667},
	{p: "edin", str: "foo.TexteditNum", want: 0.125},
	{p: "ediu", str: "foo.TexteditNum", want: 0},
	// We want the next two items to have roughly similar scores.
	{p: "up", str: "unique_ptr", want: 0.75},
	{p: "up", str: "upper_bound", want: 1},
}

func TestScores(t *testing.T) {
	for _, tc := range scoreTestCases {
		matcher := fuzzy.NewMatcher(tc.p)
		got := math.Round(float64(matcher.Score(tc.str))*1e5) / 1e5
		if got != tc.want {
			t.Errorf("Score(%s, %s) = %v, want: %v", tc.p, tc.str, got, tc.want)
		}
	}
}

func highlightMatches(str string, matcher *fuzzy.Matcher) string {
	matches := matcher.MatchedRanges()

	var buf bytes.Buffer
	index := 0
	for i := 0; i < len(matches)-1; i += 2 {
		s, e := matches[i], matches[i+1]
		fmt.Fprintf(&buf, "%s[%s]", str[index:s], str[s:e])
		index = e
	}
	buf.WriteString(str[index:])
	return buf.String()
}

func BenchmarkMatcher(b *testing.B) {
	pattern := "Foo"
	candidates := []string{
		"F_o_o",
		"Barfoo",
		"Faoo",
		"F__oo",
		"F_oo",
		"FaoFooa",
		"BarFoo",
		"FooA",
		"FooBar",
		"Foo",
	}

	matcher := fuzzy.NewMatcher(pattern)

	for b.Loop() {
		for _, c := range candidates {
			matcher.Score(c)
		}
	}
	var numBytes int
	for _, c := range candidates {
		numBytes += len(c)
	}
	b.SetBytes(int64(numBytes))
}


================================================
FILE: gopls/internal/fuzzy/self_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuzzy_test

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/fuzzy"
)

func BenchmarkSelf_Matcher(b *testing.B) {
	idents := collectIdentifiers(b)
	patterns := generatePatterns()

	for b.Loop() {
		for _, pattern := range patterns {
			sm := NewMatcher(pattern)
			for _, ident := range idents {
				_ = sm.Score(ident)
			}
		}
	}
}

func BenchmarkSelf_SymbolMatcher(b *testing.B) {
	idents := collectIdentifiers(b)
	patterns := generatePatterns()

	for b.Loop() {
		for _, pattern := range patterns {
			sm := NewSymbolMatcher(pattern)
			for _, ident := range idents {
				_, _ = sm.Match([]string{ident})
			}
		}
	}
}


================================================
FILE: gopls/internal/fuzzy/symbol.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuzzy

import (
	"bytes"
	"fmt"
	"log"
	"unicode"
)

// SymbolMatcher implements a fuzzy matching algorithm optimized for Go symbols
// of the form:
//
//	example.com/path/to/package.object.field
//
// Knowing that we are matching symbols like this allows us to make the
// following optimizations:
//   - We can incorporate right-to-left relevance directly into the score
//     calculation.
//   - We can match from right to left, discarding leading bytes if the input is
//     too long.
//   - We just take the right-most match without losing too much precision. This
//     allows us to use an O(n) algorithm.
//   - We can operate directly on chunked strings; in many cases we will
//     be storing the package path and/or package name separately from the
//     symbol or identifiers, so doing this avoids allocating strings.
//   - We can return the index of the right-most match, allowing us to trim
//     irrelevant qualification.
type SymbolMatcher struct {
	// Using buffers of length 256 is both a reasonable size for most qualified
	// symbols, and makes it easy to avoid bounds checks by using uint8 indexes.
	pattern     [256]rune
	patternLen  uint8
	inputBuffer [256]rune   // avoid allocating when considering chunks
	roles       [256]uint32 // which roles does a rune play (word start, etc.)
	segments    [256]uint8  // how many segments from the right is each rune
}

// Rune roles.
const (
	segmentStart uint32 = 1 << iota // input rune starts a segment (i.e. follows '/' or '.')
	wordStart                       // input rune starts a word, per camel-case naming rules
	separator                       // input rune is a separator ('/' or '.')
	upper                           // input rune is an upper case letter
)

// NewSymbolMatcher creates a SymbolMatcher that may be used to match the given
// search pattern.
//
// Currently this matcher only accepts case-insensitive fuzzy patterns.
//
// An empty pattern matches no input.
func NewSymbolMatcher(pattern string) *SymbolMatcher {
	m := &SymbolMatcher{}
	for _, p := range pattern {
		m.pattern[m.patternLen] = unicode.ToLower(p)
		m.patternLen++
		if m.patternLen == 255 || int(m.patternLen) == len(pattern) {
			// break at 255 so that we can represent patternLen with a uint8.
			break
		}
	}
	return m
}

// Match searches for the right-most match of the search pattern within the
// symbol represented by concatenating the given chunks.
//
// If a match is found, the first result holds the absolute byte offset within
// all chunks for the start of the symbol. In other words, the index of the
// match within strings.Join(chunks, "").
//
// The second return value will be the score of the match, which is always
// between 0 and 1, inclusive. A score of 0 indicates no match.
//
// If no match is found, Match returns (-1, 0).
func (m *SymbolMatcher) Match(chunks []string) (int, float64) {
	// Explicit behavior for an empty pattern.
	//
	// As a minor optimization, this also avoids nilness checks later on, since
	// the compiler can prove that m != nil.
	if m.patternLen == 0 {
		return -1, 0
	}

	// Matching implements a heavily optimized linear scoring algorithm on the
	// input. This is not guaranteed to produce the highest score, but works well
	// enough, particularly due to the right-to-left significance of qualified
	// symbols.
	//
	// Matching proceeds in three passes through the input:
	//  - The first pass populates the input buffer and collects rune roles.
	//  - The second pass proceeds right-to-left to find the right-most match.
	//  - The third pass proceeds left-to-right from the start of the right-most
	//    match, to find the most *compact* match, and computes the score of this
	//    match.
	//
	// See below for more details of each pass, as well as the scoring algorithm.

	// First pass: populate the input buffer out of the provided chunks
	// (lower-casing in the process), and collect rune roles.
	//
	// We could also check for a forward match here, but since we'd have to write
	// the entire input anyway this has negligible impact on performance.
	var (
		inputLen  = uint8(0)
		modifiers = wordStart | segmentStart
	)

input:
	for _, chunk := range chunks {
		for _, r := range chunk {
			if r == '.' || r == '/' {
				modifiers |= separator
			}
			// optimization: avoid calls to unicode.ToLower, which can't be inlined.
			l := r
			if r <= unicode.MaxASCII {
				if 'A' <= r && r <= 'Z' {
					l = r + 'a' - 'A'
				}
			} else {
				l = unicode.ToLower(r)
			}
			if l != r {
				modifiers |= upper

				// If the current rune is capitalized *and the preceding rune was not*,
				// mark this as a word start. This avoids spuriously high ranking of
				// non-camelcase naming schemas, such as the
				// yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE example of
				// golang/go#60201.
				if inputLen == 0 || m.roles[inputLen-1]&upper == 0 {
					modifiers |= wordStart
				}
			}
			m.inputBuffer[inputLen] = l
			m.roles[inputLen] = modifiers
			inputLen++
			if m.roles[inputLen-1]&separator != 0 {
				modifiers = wordStart | segmentStart
			} else {
				modifiers = 0
			}
			// TODO: we should prefer the right-most input if it overflows, rather
			//       than the left-most as we're doing here.
			if inputLen == 255 {
				break input
			}
		}
	}

	// Second pass: find the right-most match, and count segments from the
	// right.
	var (
		pi    = uint8(m.patternLen - 1) // pattern index
		p     = m.pattern[pi]           // pattern rune
		start = -1                      // start offset of match
		rseg  = uint8(0)                // effective "depth" from the right of the current rune in consideration
	)
	const maxSeg = 3 // maximum number of segments from the right to count, for scoring purposes.

	for ii := inputLen - 1; ; ii-- {
		r := m.inputBuffer[ii]
		if rseg < maxSeg && m.roles[ii]&separator != 0 {
			rseg++
		}
		m.segments[ii] = rseg
		if p == r {
			if pi == 0 {
				// TODO(rfindley): BUG: the docstring for Match says that it returns an
				// absolute byte offset, but clearly it is returning a rune offset here.
				start = int(ii)
				break
			}
			pi--
			p = m.pattern[pi]
		}
		// Don't check ii >= 0 in the loop condition: ii is a uint8.
		if ii == 0 {
			break
		}
	}

	if start < 0 {
		// no match: skip scoring
		return -1, 0
	}

	// Third pass: find the shortest match and compute the score.

	// Score is the average score for each rune.
	//
	// A rune score is the multiple of:
	//   1. The base score, which is 1.0 if the rune starts a segment, 0.9 if the
	//      rune starts a mid-segment word, else 0.6.
	//
	//      Runes preceded by a matching rune are treated the same as the start
	//      of a mid-segment word (with a 0.9 score), so that sequential or exact
	//      matches are preferred. We call this a sequential bonus.
	//
	//      For the final rune match, this sequential bonus is reduced to 0.8 if
	//      the next rune in the input is a mid-segment word, or 0.7 if the next
	//      rune in the input is not a word or segment start. This ensures that
	//      we favor whole-word or whole-segment matches over prefix matches.
	//
	//   2. 1.0 if the rune is part of the last segment, otherwise
	//      1.0-0.1*<segments from the right>, with a max segment count of 3.
	//      Notably 1.0-0.1*3 = 0.7 > 0.6, so that foo/_/_/_/_ (a match very
	//      early in a qualified symbol name) still scores higher than _f_o_o_ (a
	//      completely split match).
	//
	// This is a naive algorithm, but it is fast. There's lots of prior art here
	// that could be leveraged. For example, we could explicitly consider
	// rune distance, and exact matches of words or segments.
	//
	// Also note that this might not actually find the highest scoring match, as
	// doing so could require a non-linear algorithm, depending on how the score
	// is calculated.

	// debugging support
	const debug = false // enable to log debugging information
	var (
		runeScores []float64
		runeIdxs   []int
	)

	pi = 0
	p = m.pattern[pi]

	const (
		segStartScore = 1.0 // base score of runes starting a segment
		wordScore     = 0.9 // base score of runes starting or continuing a word
		noStreak      = 0.6
		perSegment    = 0.1 // we count at most 3 segments above
	)

	totScore := 0.0
	lastMatch := uint8(255)
	for ii := uint8(start); ii < inputLen; ii++ {
		r := m.inputBuffer[ii]
		if r == p {
			pi++
			finalRune := pi >= m.patternLen
			p = m.pattern[pi]

			baseScore := noStreak

			// Calculate the sequence bonus based on preceding matches.
			//
			// We do this first as it is overridden by role scoring below.
			if lastMatch == ii-1 {
				baseScore = wordScore
				// Reduce the sequence bonus for the final rune of the pattern based on
				// whether it borders a new segment or word.
				if finalRune {
					switch {
					case ii == inputLen-1 || m.roles[ii+1]&separator != 0:
						// Full segment: no reduction
					case m.roles[ii+1]&wordStart != 0:
						baseScore = wordScore - 0.1
					default:
						baseScore = wordScore - 0.2
					}
				}
			}
			lastMatch = ii

			// Calculate the rune's role score. If the rune starts a segment or word,
			// this overrides the sequence score, as the rune starts a new sequence.
			switch {
			case m.roles[ii]&segmentStart != 0:
				baseScore = segStartScore
			case m.roles[ii]&wordStart != 0:
				baseScore = wordScore
			}

			// Apply the segment-depth penalty (segments from the right).
			runeScore := baseScore * (1.0 - float64(m.segments[ii])*perSegment)
			if debug {
				runeScores = append(runeScores, runeScore)
				runeIdxs = append(runeIdxs, int(ii))
			}
			totScore += runeScore
			if finalRune {
				break
			}
		}
	}

	if debug {
		// Format rune roles and scores in line:
		// fo[o:.52].[b:1]a[r:.6]
		var summary bytes.Buffer
		last := 0
		for i, idx := range runeIdxs {
			summary.WriteString(string(m.inputBuffer[last:idx])) // encode runes
			fmt.Fprintf(&summary, "[%s:%.2g]", string(m.inputBuffer[idx]), runeScores[i])
			last = idx + 1
		}
		summary.WriteString(string(m.inputBuffer[last:inputLen])) // encode runes
		log.Println(summary.String())
	}

	return start, totScore / float64(m.patternLen)
}


================================================
FILE: gopls/internal/fuzzy/symbol_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fuzzy_test

import (
	"go/ast"
	"go/token"
	"sort"
	"testing"

	"golang.org/x/tools/go/packages"
	. "golang.org/x/tools/gopls/internal/fuzzy"
)

func TestSymbolMatchIndex(t *testing.T) {
	tests := []struct {
		pattern, input string
		want           int
	}{
		{"test", "foo.TestFoo", 4},
		{"test", "test", 0},
		{"test", "Test", 0},
		{"test", "est", -1},
		{"t", "shortest", 7},
		{"", "foo", -1},
		{"", string([]rune{0}), -1}, // verify that we don't default to an empty pattern.
		{"anything", "", -1},
	}

	for _, test := range tests {
		matcher := NewSymbolMatcher(test.pattern)
		if got, _ := matcher.Match([]string{test.input}); got != test.want {
			t.Errorf("NewSymbolMatcher(%q).Match(%q) = %v, _, want %v, _", test.pattern, test.input, got, test.want)
		}
	}
}

func TestSymbolRanking(t *testing.T) {

	// query -> symbols to match, in ascending order of score
	queryRanks := map[string][]string{
		"test": {
			"this.is.better.than.most",
			"test.foo.bar",
			"thebest",
			"atest",
			"test.foo",
			"testage",
			"tTest",
			"foo.test",
		},
		"parseside": { // golang/go#60201
			"yaml_PARSE_FLOW_SEQUENCE_ENTRY_MAPPING_END_STATE",
			"parseContext.parse_sidebyside",
		},
		"cvb": {
			"filecache_test.testIPCValueB",
			"cover.Boundary",
		},
		"dho": {
			"gocommand.DebugHangingGoCommands",
			"protocol.DocumentHighlightOptions",
		},
		"flg": {
			"completion.FALLTHROUGH",
			"main.flagGoCmd",
		},
		"fvi": {
			"godoc.fileIndexVersion",
			"macho.FlagSubsectionsViaSymbols",
		},
	}

	for query, symbols := range queryRanks {
		t.Run(query, func(t *testing.T) {
			matcher := NewSymbolMatcher(query)
			prev := 0.0
			for _, sym := range symbols {
				_, score := matcher.Match([]string{sym})
				t.Logf("Match(%q) = %v", sym, score)
				if score <= prev {
					t.Errorf("Match(%q) = _, %v, want > %v", sym, score, prev)
				}
				prev = score
			}
		})
	}
}

func TestMatcherSimilarities(t *testing.T) {
	// This test compares the fuzzy matcher with the symbol matcher on a corpus
	// of qualified identifiers extracted from x/tools.
	//
	// These two matchers are not expected to agree, but inspecting differences
	// can be useful for finding interesting ranking edge cases.
	t.Skip("unskip this test to compare matchers")

	idents := collectIdentifiers(t)
	t.Logf("collected %d unique identifiers", len(idents))

	// We can't use slices.MaxFunc because we want a custom
	// scoring (not equivalence) function.
	topMatch := func(score func(string) float64) string {
		top := ""
		topScore := 0.0
		for _, cand := range idents {
			if s := score(cand); s > topScore {
				top = cand
				topScore = s
			}
		}
		return top
	}

	agreed := 0
	total := 0
	bad := 0
	patterns := generatePatterns()
	for _, pattern := range patterns {
		total++

		fm := NewMatcher(pattern)
		topFuzzy := topMatch(func(input string) float64 {
			return float64(fm.Score(input))
		})
		sm := NewSymbolMatcher(pattern)
		topSymbol := topMatch(func(input string) float64 {
			_, score := sm.Match([]string{input})
			return score
		})
		switch {
		case topFuzzy == "" && topSymbol != "":
			if false {
				// The fuzzy matcher has a bug where it misses some matches; for this
				// test we only care about the symbol matcher.
				t.Logf("%q matched %q but no fuzzy match", pattern, topSymbol)
			}
			total--
			bad++
		case topFuzzy != "" && topSymbol == "":
			t.Fatalf("%q matched %q but no symbol match", pattern, topFuzzy)
		case topFuzzy == topSymbol:
			agreed++
		default:
			// Enable this log to see mismatches.
			if false {
				t.Logf("mismatch for %q: fuzzy: %q, symbol: %q", pattern, topFuzzy, topSymbol)
			}
		}
	}
	t.Logf("fuzzy matchers agreed on %d out of %d queries (%d bad)", agreed, total, bad)
}

func collectIdentifiers(tb testing.TB) []string {
	cfg := &packages.Config{
		Mode:  packages.NeedName | packages.NeedSyntax | packages.NeedFiles,
		Tests: true,
	}
	pkgs, err := packages.Load(cfg, "golang.org/x/tools/...")
	if err != nil {
		tb.Fatal(err)
	}
	uniqueIdents := make(map[string]bool)
	decls := 0
	for _, pkg := range pkgs {
		for _, f := range pkg.Syntax {
			for _, decl := range f.Decls {
				decls++
				switch decl := decl.(type) {
				case *ast.GenDecl:
					for _, spec := range decl.Specs {
						switch decl.Tok {
						case token.IMPORT:
						case token.TYPE:
							name := spec.(*ast.TypeSpec).Name.Name
							qualified := pkg.Name + "." + name
							uniqueIdents[qualified] = true
						case token.CONST, token.VAR:
							for _, n := range spec.(*ast.ValueSpec).Names {
								qualified := pkg.Name + "." + n.Name
								uniqueIdents[qualified] = true
							}
						}
					}
				}
			}
		}
	}
	var idents []string
	for k := range uniqueIdents {
		idents = append(idents, k)
	}
	sort.Strings(idents)
	return idents
}

func generatePatterns() []string {
	var patterns []string
	for x := 'a'; x <= 'z'; x++ {
		for y := 'a'; y <= 'z'; y++ {
			for z := 'a'; z <= 'z'; z++ {
				patterns = append(patterns, string(x)+string(y)+string(z))
			}
		}
	}
	return patterns
}

// Test that we strongly prefer exact matches.
//
// In golang/go#60027, we preferred "Runner" for the query "rune" over several
// results containing the word "rune" exactly. Following this observation,
// scoring was tweaked to more strongly emphasize sequential characters and
// exact matches.
func TestSymbolRanking_Issue60027(t *testing.T) {
	matcher := NewSymbolMatcher("rune")

	// symbols to match, in ascending order of ranking.
	symbols := []string{
		"Runner",
		"singleRuneParam",
		"Config.ifsRune",
		"Parser.rune",
	}
	prev := 0.0
	for _, sym := range symbols {
		_, score := matcher.Match([]string{sym})
		t.Logf("Match(%q) = %v", sym, score)
		if score < prev {
			t.Errorf("Match(%q) = _, %v, want > %v", sym, score, prev)
		}
		prev = score
	}
}

func TestChunkedMatch(t *testing.T) {
	matcher := NewSymbolMatcher("test")
	_, want := matcher.Match([]string{"test"})
	chunked := [][]string{
		{"", "test"},
		{"test", ""},
		{"te", "st"},
	}

	for _, chunks := range chunked {
		offset, score := matcher.Match(chunks)
		if offset != 0 || score != want {
			t.Errorf("Match(%v) = %v, %v, want 0, 1.0", chunks, offset, score)
		}
	}
}


================================================
FILE: gopls/internal/goasm/definition.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package goasm provides language-server features for files in Go
// assembly language (https://go.dev/doc/asm).
package goasm

import (
	"context"
	"fmt"
	"go/token"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/asm"
	"golang.org/x/tools/gopls/internal/util/morestrings"
	"golang.org/x/tools/internal/event"
)

// Definition handles the textDocument/definition request for Go assembly files.
func Definition(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	ctx, done := event.Start(ctx, "goasm.Definition")
	defer done()

	mp, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
	if err != nil {
		return nil, err
	}

	// Read the file.
	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	mapper := protocol.NewMapper(fh.URI(), content)
	start, end, err := mapper.RangeOffsets(rng)
	if err != nil {
		return nil, err
	}

	// Parse the assembly.
	//
	// TODO(adonovan): make this just another
	// attribute of the type-checked cache.Package.
	file := asm.Parse(content)

	// Figure out the selected symbol.
	// For now, just find the identifier around the cursor.
	var found *asm.Ident
	for _, id := range file.Idents {
		if id.Offset <= start && end <= id.End() {
			found = &id
			break
		}
	}
	if found == nil {
		return nil, fmt.Errorf("not an identifier")
	}

	// Resolve a symbol with a "." prefix to the current package.
	sym := found.Name
	if sym != "" && sym[0] == '.' {
		sym = string(mp.PkgPath) + sym
	}

	// package-qualified symbol?
	if pkgpath, name, ok := morestrings.CutLast(sym, "."); ok {
		// Find declaring package among dependencies.
		//
		// TODO(adonovan): assembly may legally reference
		// non-dependencies. For example, sync/atomic calls
		// internal/runtime/atomic. Perhaps we should search
		// the entire metadata graph, but that's path-dependent.
		var declaring *metadata.Package
		for pkg := range snapshot.MetadataGraph().ForwardReflexiveTransitiveClosure(mp.ID) {
			if pkg.PkgPath == metadata.PackagePath(pkgpath) {
				declaring = pkg
				break
			}
		}
		if declaring == nil {
			return nil, fmt.Errorf("package %q is not a dependency", pkgpath)
		}

		// Find declared symbol in syntax package.
		pkgs, err := snapshot.TypeCheck(ctx, declaring.ID)
		if err != nil {
			return nil, err
		}
		pkg := pkgs[0]
		def := pkg.Types().Scope().Lookup(name)
		if def == nil {
			return nil, fmt.Errorf("no symbol %q in package %q", name, pkgpath)
		}

		// Map position.
		pos := def.Pos()
		pgf, err := pkg.FileEnclosing(pos)
		if err != nil {
			return nil, err
		}
		loc, err := pgf.PosLocation(pos, pos+token.Pos(len(name)))
		if err != nil {
			return nil, err
		}
		return []protocol.Location{loc}, nil

	} else {
		// local symbols (funcs, vars, labels)
		for _, id := range file.Idents {
			if id.Name == found.Name &&
				(id.Kind == asm.Text || id.Kind == asm.Global || id.Kind == asm.Label) {

				loc, err := mapper.OffsetLocation(id.Offset, id.End())
				if err != nil {
					return nil, err
				}
				return []protocol.Location{loc}, nil
			}
		}
	}

	return nil, nil
}


================================================
FILE: gopls/internal/golang/add_import.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/imports"
)

// AddImport adds a single import statement to the given file
func AddImport(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, importPath string) ([]protocol.TextEdit, error) {
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}
	return ComputeImportFixEdits(snapshot.Options().Local, pgf.Src, &imports.ImportFix{
		StmtInfo: imports.ImportInfo{
			ImportPath: importPath,
		},
		FixType: imports.AddImport,
	})
}


================================================
FILE: gopls/internal/golang/addtest.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines the behavior of the "Add test for FUNC" command.

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/format"
	"go/types"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"text/template"
	"unicode"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/typesinternal"
)

const testTmplString = `
func {{.TestFuncName}}(t *{{.TestingPackageName}}.T) {
	{{- /* Test cases struct declaration and empty initialization. */}}
	tests := []struct {
		name string // description of this test case

		{{- $commentPrinted := false }}
		{{- if and .Receiver .Receiver.Constructor}}
		{{- range .Receiver.Constructor.Args}}
		{{- if .Name}}
		{{- if not $commentPrinted}}
		// Named input parameters for receiver constructor.
		{{- $commentPrinted = true }}
		{{- end}}
		{{.Name}} {{.Type}}
		{{- end}}
		{{- end}}
		{{- end}}

		{{- $commentPrinted := false }}
		{{- range .Func.Args}}
		{{- if .Name}}
		{{- if not $commentPrinted}}
		// Named input parameters for target function.
		{{- $commentPrinted = true }}
		{{- end}}
		{{.Name}} {{.Type}}
		{{- end}}
		{{- end}}

		{{- range $index, $res := .Func.Results}}
		{{- if eq $res.Name "gotErr"}}
		wantErr bool
		{{- else if eq $index 0}}
		want {{$res.Type}}
		{{- else}}
		want{{add $index 1}} {{$res.Type}}
		{{- end}}
		{{- end}}
	}{
		// TODO: Add test cases.
	}

	{{- /* Loop over all the test cases. */}}
	for _, tt := range tests {
		t.Run(tt.name, func(t *{{.TestingPackageName}}.T) {
			{{- /* Constructor or empty initialization. */}}
			{{- if .Receiver}}
			{{- if .Receiver.Constructor}}
			{{- /* Receiver variable by calling constructor. */}}
			{{fieldNames .Receiver.Constructor.Results ""}} := {{if .PackageName}}{{.PackageName}}.{{end}}
			{{- .Receiver.Constructor.Name}}

			{{- /* Constructor input parameters. */ -}}
			(
				{{- range $index, $arg := .Receiver.Constructor.Args}}
				{{- if ne $index 0}}, {{end}}
				{{- if .Name}}tt.{{.Name}}{{else}}{{.Value}}{{end}}
				{{- end -}}
				{{- if and .Receiver.Constructor.IsVariadic (not .Receiver.Constructor.IsUnusedVariadic) }}...{{- end -}}
			)

			{{- /* Handles the error return from constructor. */}}
			{{- $last := last .Receiver.Constructor.Results}}
			{{- if eq $last.Type "error"}}
			if err != nil {
				t.Fatalf("could not construct receiver type: %v", err)
			}
			{{- end}}
			{{- else}}
			{{- /* Receiver variable declaration. */}}
			// TODO: construct the receiver type.
			var {{.Receiver.Var.Name}} {{.Receiver.Var.Type}}
			{{- end}}
			{{- end}}

			{{- /* Got variables. */}}
			{{if .Func.Results}}{{fieldNames .Func.Results ""}} := {{end}}

			{{- /* Call expression. */}}
			{{- if .Receiver}}{{/* Call method by VAR.METHOD. */}}
			{{- .Receiver.Var.Name}}.
			{{- else if .PackageName}}{{/* Call function by PACKAGE.FUNC. */}}
			{{- .PackageName}}.
			{{- end}}{{.Func.Name}}

			{{- /* Input parameters. */ -}}
			(
				{{- range $index, $arg := .Func.Args}}
				{{- if ne $index 0}}, {{end}}
				{{- if .Name}}tt.{{.Name}}{{else}}{{.Value}}{{end}}
				{{- end -}}
				{{- if and .Func.IsVariadic (not .Func.IsUnusedVariadic) }}...{{- end -}}
			)

			{{- /* Handles the returned error before the rest of return value. */}}
			{{- $last := last .Func.Results}}
			{{- if eq $last.Type "error"}}
			if gotErr != nil {
				if !tt.wantErr {
					t.Errorf("{{$.Func.Name}}() failed: %v", gotErr)
				}
				return
			}
			if tt.wantErr {
				t.Fatal("{{$.Func.Name}}() succeeded unexpectedly")
			}
			{{- end}}

			{{- /* Compare the returned values except for the last returned error. */}}
			{{- if or (and .Func.Results (ne $last.Type "error")) (and (gt (len .Func.Results) 1) (eq $last.Type "error"))}}
			// TODO: update the condition below to compare got with tt.want.
			{{- range $index, $res := .Func.Results}}
			{{- if ne $res.Name "gotErr"}}
			if true {
				t.Errorf("{{$.Func.Name}}() = %v, want %v", {{.Name}}, tt.{{if eq $index 0}}want{{else}}want{{add $index 1}}{{end}})
			}
			{{- end}}
			{{- end}}
			{{- end}}
		})
	}
}
`

// Name is the name of the field this input parameter should reference.
// Value is the expression this input parameter should accept.
//
// Exactly one of Name or Value must be set.
type field struct {
	Name, Type, Value string
}

type function struct {
	Name    string
	Args    []field
	Results []field
	// IsVariadic holds information if the function is variadic.
	// In case of the IsVariadic=true must expand it in the function-under-test call.
	IsVariadic bool
	// IsUnusedVariadic holds information if the function's variadic args is not used.
	// In this case ... must be skipped.
	IsUnusedVariadic bool
}

type receiver struct {
	// Var is the name and type of the receiver variable.
	Var field
	// Constructor holds information about the constructor for the receiver type.
	// If no qualified constructor is found, this field will be nil.
	Constructor *function
}

type testInfo struct {
	// TestingPackageName is the package name should be used when referencing
	// package "testing"
	TestingPackageName string
	// PackageName is the package name the target function/method is declared from.
	PackageName  string
	TestFuncName string
	// Func holds information about the function or method being tested.
	Func function
	// Receiver holds information about the receiver of the function or method
	// being tested.
	// This field is nil for functions and non-nil for methods.
	Receiver *receiver
}

var testTmpl = template.Must(template.New("test").Funcs(template.FuncMap{
	"add": func(a, b int) int { return a + b },
	"last": func(slice []field) field {
		if len(slice) == 0 {
			return field{}
		}
		return slice[len(slice)-1]
	},
	"fieldNames": func(fields []field, qualifier string) (res string) {
		var names []string
		for _, f := range fields {
			names = append(names, qualifier+f.Name)
		}
		return strings.Join(names, ", ")
	},
}).Parse(testTmplString))

// AddTestForFunc adds a test for the function enclosing the given input range.
// It creates a _test.go file if one does not already exist.
// It returns the required text edits and the predicted location of the new test
// function, which is only valid after the edits have been successfully applied.
func AddTestForFunc(ctx context.Context, snapshot *cache.Snapshot, loc protocol.Location) (changes []protocol.DocumentChange, show *protocol.Location, _ error) {
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, loc.URI)
	if err != nil {
		return nil, nil, err
	}

	if metadata.IsCommandLineArguments(pkg.Metadata().ID) {
		return nil, nil, fmt.Errorf("current file in command-line-arguments package")
	}

	if errors := pkg.ParseErrors(); len(errors) > 0 {
		return nil, nil, fmt.Errorf("package has parse errors: %v", errors[0])
	}
	if errors := pkg.TypeErrors(); len(errors) > 0 {
		return nil, nil, fmt.Errorf("package has type errors: %v", errors[0])
	}

	// All three maps map the path of an imported package to
	// the local name if explicit or "" otherwise.
	var (
		fileImports  map[string]string         // imports in foo.go file
		testImports  map[string]string         // imports in foo_test.go file
		extraImports = make(map[string]string) // imports to add to test file
	)

	collectImports := func(file *ast.File) (map[string]string, error) {
		imps := make(map[string]string)
		for _, spec := range file.Imports {
			// TODO(hxjiang): support dot imports.
			if spec.Name != nil && spec.Name.Name == "." {
				return nil, fmt.Errorf("\"add test for func\" does not support files containing dot imports")
			}
			path, err := strconv.Unquote(spec.Path.Value)
			if err != nil {
				return nil, err
			}
			if spec.Name != nil {
				if spec.Name.Name == "_" {
					continue
				}
				imps[path] = spec.Name.Name
			} else {
				imps[path] = ""
			}
		}
		return imps, nil
	}

	// Collect all the imports from the x.go, keep track of the local package name.
	if fileImports, err = collectImports(pgf.File); err != nil {
		return nil, nil, err
	}

	testBase := strings.TrimSuffix(loc.URI.Base(), ".go") + "_test.go"
	goTestFileURI := protocol.URIFromPath(filepath.Join(loc.URI.DirPath(), testBase))

	testFH, err := snapshot.ReadFile(ctx, goTestFileURI)
	if err != nil {
		return nil, nil, err
	}

	// TODO(hxjiang): use a fresh name if the same test function name already
	// exist.

	var (
		eofRange protocol.Range // empty selection at end of new file
		// edits contains all the text edits to be applied to the test file.
		edits []protocol.TextEdit
		// xtest indicates whether the test file use package x or x_test.
		// TODO(hxjiang): We can discuss the option to interpret the user's
		// intention by which function they are selecting. Have one file for
		// x_test package testing, one file for x package testing.
		xtest = true
	)

	start, end, err := pgf.RangePos(loc.Range)
	if err != nil {
		return nil, nil, err
	}

	path, _ := goastutil.PathEnclosingInterval(pgf.File, start, end)
	if len(path) < 2 {
		return nil, nil, fmt.Errorf("no enclosing function")
	}

	decl, ok := path[len(path)-2].(*ast.FuncDecl)
	if !ok {
		return nil, nil, fmt.Errorf("no enclosing function")
	}

	fn := pkg.TypesInfo().Defs[decl.Name].(*types.Func)
	sig := fn.Signature()

	testPGF, err := snapshot.ParseGo(ctx, testFH, parsego.Header)
	if err != nil {
		if !errors.Is(err, os.ErrNotExist) {
			return nil, nil, err
		}
		changes = append(changes, protocol.DocumentChangeCreate(goTestFileURI))

		// header is the buffer containing the text to add to the beginning of the file.
		var header bytes.Buffer

		// If this test file was created by the gopls, add a copyright header and
		// package decl based on the originating file.
		// Search for something that looks like a copyright header, to replicate
		// in the new file.
		if c := CopyrightComment(pgf.File); c != nil {
			text, err := pgf.NodeText(c)
			if err != nil {
				return nil, nil, err
			}
			header.Write(text)
			// One empty line between copyright header and following.
			header.WriteString("\n\n")
		}

		// If this test file was created by gopls, add build constraints
		// matching the non-test file.
		if c := buildConstraintComment(pgf.File); c != nil {
			text, err := pgf.NodeText(c)
			if err != nil {
				return nil, nil, err
			}
			header.Write(text)
			// One empty line between build constraint and following.
			header.WriteString("\n\n")
		}

		// Determine if a new test file should use in-package test (package x)
		// or external test (package x_test). If any of the function parameters
		// reference an unexported object, we cannot write out test cases from
		// an x_test package.
		externalTestOK := func() bool {
			if !fn.Exported() {
				return false
			}
			if fn.Signature().Recv() != nil {
				if _, ident, _ := astutil.UnpackRecv(decl.Recv.List[0].Type); ident == nil || !ident.IsExported() {
					return false
				}
			}
			refsUnexported := false
			ast.Inspect(decl, func(n ast.Node) bool {
				// The original function refs to an unexported object from the
				// same package, so further inspection is unnecessary.
				if refsUnexported {
					return false
				}
				switch t := n.(type) {
				case *ast.BlockStmt:
					// Avoid inspect the function body.
					return false
				case *ast.Ident:
					// Use test variant (package foo) if the function signature
					// references any unexported objects (like types or
					// constants) from the same package.
					// Note: types.PkgName is excluded from this check as it's
					// always defined in the same package.
					if obj, ok := pkg.TypesInfo().Uses[t]; ok && !obj.Exported() && obj.Pkg() == pkg.Types() && !is[*types.PkgName](obj) {
						refsUnexported = true
					}
					return false
				default:
					return true
				}
			})
			return !refsUnexported
		}

		xtest = externalTestOK()
		if xtest {
			fmt.Fprintf(&header, "package %s_test\n", pkg.Types().Name())
		} else {
			fmt.Fprintf(&header, "package %s\n", pkg.Types().Name())
		}

		// Write the copyright and package decl to the beginning of the file.
		edits = append(edits, protocol.TextEdit{
			Range:   protocol.Range{},
			NewText: header.String(),
		})
	} else { // existing _test.go file.
		file := testPGF.File
		if !file.Name.NamePos.IsValid() {
			return nil, nil, fmt.Errorf("missing package declaration")
		}
		switch file.Name.Name {
		case pgf.File.Name.Name:
			xtest = false
		case pgf.File.Name.Name + "_test":
			xtest = true
		default:
			return nil, nil, fmt.Errorf("invalid package declaration %q in test file %q", file.Name, testPGF)
		}

		eofRange, err = testPGF.PosRange(file.FileEnd, file.FileEnd)
		if err != nil {
			return nil, nil, err
		}

		// Collect all the imports from the foo_test.go.
		if testImports, err = collectImports(file); err != nil {
			return nil, nil, err
		}
	}

	// qual qualifier determines the correct package name to use for a type in
	// foo_test.go. It does this by:
	// - Consult imports map from test file foo_test.go.
	// - If not found, consult imports map from original file foo.go.
	// If the package is not imported in test file foo_test.go, it is added to
	// extraImports map.
	qual := func(p *types.Package) string {
		// References from an in-package test should not be qualified.
		if !xtest && p == pkg.Types() {
			return ""
		}
		// Prefer using the package name if already defined in foo_test.go
		if local, ok := testImports[p.Path()]; ok {
			if local != "" {
				return local
			} else {
				return p.Name()
			}
		}
		// TODO(hxjiang): we should consult the scope of the test package to
		// ensure these new imports do not shadow any package-level names.
		// Prefer the local import name (if any) used in the package under test.
		if local, ok := fileImports[p.Path()]; ok && local != "" {
			extraImports[p.Path()] = local
			return local
		}
		// Fall back to the package name since there is no renaming.
		extraImports[p.Path()] = ""
		return p.Name()
	}

	if xtest {
		// Reject if function/method is unexported.
		if !fn.Exported() {
			return nil, nil, fmt.Errorf("cannot add test of unexported function %s to external test package %s_test", decl.Name, pgf.File.Name)
		}

		// Reject if receiver is unexported.
		if sig.Recv() != nil {
			if _, ident, _ := astutil.UnpackRecv(decl.Recv.List[0].Type); ident == nil || !ident.IsExported() {
				return nil, nil, fmt.Errorf("cannot add external test for method %s.%s as receiver type is not exported", ident.Name, decl.Name)
			}
		}
		// TODO(hxjiang): reject if the any input parameter type is unexported.
		// TODO(hxjiang): reject if any return value type is unexported. Explore
		// the option to drop the return value if the type is unexported.
	}

	testName, err := testName(fn)
	if err != nil {
		return nil, nil, err
	}

	data := testInfo{
		TestingPackageName: qual(types.NewPackage("testing", "testing")),
		PackageName:        qual(pkg.Types()),
		TestFuncName:       testName,
		Func: function{
			Name:       fn.Name(),
			IsVariadic: sig.Variadic(),
		},
	}

	isContextType := func(t types.Type) bool {
		return typesinternal.IsTypeNamed(t, "context", "Context")
	}

	isUnusedParameter := func(name string) bool {
		return name == "" || name == "_"
	}

	for i := range sig.Params().Len() {
		param := sig.Params().At(i)
		name, typ := param.Name(), param.Type()
		f := field{Type: types.TypeString(typ, qual)}
		if i == 0 && isContextType(typ) {
			f.Value = qual(types.NewPackage("context", "context")) + ".Background()"
		} else if isUnusedParameter(name) && data.Func.IsVariadic && sig.Params().Len()-1 == i {
			// The last argument is the variadic argument, and it's not used in the function body,
			// so we don't need to render it in the test case struct.
			data.Func.IsUnusedVariadic = true
			continue
		} else if isUnusedParameter(name) {
			f.Value, _ = typesinternal.ZeroString(typ, qual)
		} else {
			f.Name = name
		}
		data.Func.Args = append(data.Func.Args, f)
	}

	for i := range sig.Results().Len() {
		typ := sig.Results().At(i).Type()
		var name string
		if i == sig.Results().Len()-1 && types.Identical(typ, errorType) {
			name = "gotErr"
		} else if i == 0 {
			name = "got"
		} else {
			name = fmt.Sprintf("got%d", i+1)
		}
		data.Func.Results = append(data.Func.Results, field{
			Name: name,
			Type: types.TypeString(typ, qual),
		})
	}

	if sig.Recv() != nil {
		// Find the preferred type for the receiver. We don't use
		// typesinternal.ReceiverNamed here as we want to preserve aliases.
		recvType := sig.Recv().Type()
		if ptr, ok := recvType.(*types.Pointer); ok {
			recvType = ptr.Elem()
		}

		t, ok := recvType.(typesinternal.NamedOrAlias)
		if !ok {
			return nil, nil, fmt.Errorf("the receiver type is neither named type nor alias type")
		}

		var varName string
		{
			var possibleNames []string // list of candidates, preferring earlier entries.
			if len(sig.Recv().Name()) > 0 {
				possibleNames = append(possibleNames,
					sig.Recv().Name(),            // receiver name.
					string(sig.Recv().Name()[0]), // first character of receiver name.
				)
			}
			possibleNames = append(possibleNames,
				string(t.Obj().Name()[0]), // first character of receiver type name.
			)
			if len(t.Obj().Name()) >= 2 {
				possibleNames = append(possibleNames,
					string(t.Obj().Name()[:2]), // first two character of receiver type name.
				)
			}
			var camelCase []rune
			for i, s := range t.Obj().Name() {
				if i == 0 || unicode.IsUpper(s) {
					camelCase = append(camelCase, s)
				}
			}
			possibleNames = append(possibleNames,
				string(camelCase), // captalized initials.
			)
			for _, name := range possibleNames {
				name = strings.ToLower(name)
				if name == "" || name == "t" || name == "tt" {
					continue
				}
				varName = name
				break
			}
			if varName == "" {
				varName = "r" // default as "r" for "receiver".
			}
		}

		data.Receiver = &receiver{
			Var: field{
				Name: varName,
				Type: types.TypeString(recvType, qual),
			},
		}

		// constructor is the selected constructor for type T.
		var constructor *types.Func

		// When finding the qualified constructor, the function should return the
		// any type whose named type is the same type as T's named type.
		_, wantType := typesinternal.ReceiverNamed(sig.Recv())
		for _, name := range pkg.Types().Scope().Names() {
			f, ok := pkg.Types().Scope().Lookup(name).(*types.Func)
			if !ok {
				continue
			}
			if f.Signature().Recv() != nil {
				continue
			}
			// Unexported constructor is not visible in x_test package.
			if xtest && !f.Exported() {
				continue
			}
			// Only allow constructors returning T, T, (T, error), or (T, error).
			if f.Signature().Results().Len() > 2 || f.Signature().Results().Len() == 0 {
				continue
			}

			_, gotType := typesinternal.ReceiverNamed(f.Signature().Results().At(0))
			if gotType == nil || !types.Identical(gotType, wantType) {
				continue
			}

			if f.Signature().Results().Len() == 2 && !types.Identical(f.Signature().Results().At(1).Type(), errorType) {
				continue
			}

			if constructor == nil {
				constructor = f
			}

			// Functions named NewType are prioritized as constructors over other
			// functions that match only the signature criteria.
			if strings.EqualFold(strings.ToLower(f.Name()), strings.ToLower("new"+t.Obj().Name())) {
				constructor = f
			}
		}

		if constructor != nil {
			data.Receiver.Constructor = &function{
				Name:       constructor.Name(),
				IsVariadic: constructor.Signature().Variadic(),
			}
			for i := range constructor.Signature().Params().Len() {
				param := constructor.Signature().Params().At(i)
				name, typ := param.Name(), param.Type()
				f := field{Type: types.TypeString(typ, qual)}
				if i == 0 && isContextType(typ) {
					f.Value = qual(types.NewPackage("context", "context")) + ".Background()"
				} else if isUnusedParameter(name) && data.Receiver.Constructor.IsVariadic && constructor.Signature().Params().Len()-1 == i {
					// The last argument is the variadic argument, and it's not used in the function body,
					// so we don't need to render it in the test case struct.
					data.Receiver.Constructor.IsUnusedVariadic = true
					continue
				} else if isUnusedParameter(name) {
					f.Value, _ = typesinternal.ZeroString(typ, qual)
				} else {
					f.Name = name
				}
				data.Receiver.Constructor.Args = append(data.Receiver.Constructor.Args, f)
			}
			for i := range constructor.Signature().Results().Len() {
				typ := constructor.Signature().Results().At(i).Type()
				var name string
				if i == 0 {
					// The first return value must be of type T, *T, or a type whose named
					// type is the same as named type of T.
					name = varName
				} else if i == constructor.Signature().Results().Len()-1 && types.Identical(typ, errorType) {
					name = "err"
				} else {
					// Drop any return values beyond the first and the last.
					// e.g., "f, _, _, err := NewFoo()".
					name = "_"
				}
				data.Receiver.Constructor.Results = append(data.Receiver.Constructor.Results, field{
					Name: name,
					Type: types.TypeString(typ, qual),
				})
			}
		}
	}

	// Resolves duplicate parameter names between the function and its
	// receiver's constructor. It adds prefix to the constructor's parameters
	// until no conflicts remain.
	if data.Receiver != nil && data.Receiver.Constructor != nil {
		seen := map[string]bool{}
		for _, f := range data.Func.Args {
			if f.Name == "" {
				continue
			}
			seen[f.Name] = true
		}

		// "" for no change, "c" for constructor, "i" for input.
		for _, prefix := range []string{"", "c", "c_", "i", "i_"} {
			conflict := false
			for _, f := range data.Receiver.Constructor.Args {
				if f.Name == "" {
					continue
				}
				if seen[prefix+f.Name] {
					conflict = true
					break
				}
			}
			if !conflict {
				for i, f := range data.Receiver.Constructor.Args {
					if f.Name == "" {
						continue
					}
					data.Receiver.Constructor.Args[i].Name = prefix + data.Receiver.Constructor.Args[i].Name
				}
				break
			}
		}
	}

	// Compute edits to update imports.
	//
	// If we're adding to an existing test file, we need to adjust existing
	// imports. Otherwise, we can simply write out the imports to the new file.
	if testPGF != nil {
		var importFixes []*imports.ImportFix
		for path, name := range extraImports {
			importFixes = append(importFixes, &imports.ImportFix{
				StmtInfo: imports.ImportInfo{
					ImportPath: path,
					Name:       name,
				},
				FixType: imports.AddImport,
			})
		}
		importEdits, err := ComputeImportFixEdits(snapshot.Options().Local, testPGF.Src, importFixes...)
		if err != nil {
			return nil, nil, fmt.Errorf("could not compute the import fix edits: %w", err)
		}
		edits = append(edits, importEdits...)
	} else {
		var importsBuffer bytes.Buffer
		if len(extraImports) == 1 {
			importsBuffer.WriteString("\nimport ")
			for path, name := range extraImports {
				if name != "" {
					importsBuffer.WriteString(name + " ")
				}
				importsBuffer.WriteString(fmt.Sprintf("\"%s\"\n", path))
			}
		} else {
			importsBuffer.WriteString("\nimport(")
			// Sort for determinism.
			for path, name := range moremaps.Sorted(extraImports) {
				importsBuffer.WriteString("\n\t")
				if name != "" {
					importsBuffer.WriteString(name + " ")
				}
				importsBuffer.WriteString(fmt.Sprintf("\"%s\"", path))
			}
			importsBuffer.WriteString("\n)\n")
		}
		edits = append(edits, protocol.TextEdit{
			Range:   protocol.Range{},
			NewText: importsBuffer.String(),
		})
	}

	var test bytes.Buffer
	if err := testTmpl.Execute(&test, data); err != nil {
		return nil, nil, err
	}

	formatted, err := format.Source(test.Bytes())
	if err != nil {
		return nil, nil, err
	}

	edits = append(edits,
		protocol.TextEdit{
			Range:   eofRange,
			NewText: string(formatted),
		},
	)

	// Show the line of generated test function.
	{
		line := eofRange.Start.Line
		for i := range len(edits) - 1 { // last edits is the func decl
			e := edits[i]
			oldLines := e.Range.End.Line - e.Range.Start.Line
			newLines := uint32(strings.Count(e.NewText, "\n"))
			line += (newLines - oldLines)
		}
		show = &protocol.Location{
			URI: testFH.URI(),
			Range: protocol.Range{
				// Test function template have a new line at beginning.
				Start: protocol.Position{Line: line + 1},
				End:   protocol.Position{Line: line + 1},
			},
		}
	}

	return append(changes, protocol.DocumentChangeEdit(testFH, edits)), show, nil
}

// testName returns the name of the function to use for the new function that
// tests fn.
// Returns empty string if the fn is ill typed or nil.
func testName(fn *types.Func) (string, error) {
	if fn == nil {
		return "", fmt.Errorf("input nil function")
	}
	testName := "Test"
	if recv := fn.Signature().Recv(); recv != nil { // method declaration.
		// Retrieve the unpointered receiver type to ensure the test name is based
		// on the topmost alias or named type, not the alias' RHS type (potentially
		// unexported) type.
		// For example:
		// type Foo = foo // Foo is an exported alias for the unexported type foo
		recvType := recv.Type()
		if ptr, ok := recv.Type().(*types.Pointer); ok {
			recvType = ptr.Elem()
		}

		t, ok := recvType.(typesinternal.NamedOrAlias)
		if !ok {
			return "", fmt.Errorf("receiver type is not named type or alias type")
		}

		if !t.Obj().Exported() {
			testName += "_"
		}

		testName += t.Obj().Name() + "_"
	} else if !fn.Exported() { // unexported function declaration.
		testName += "_"
	}
	return testName + fn.Name(), nil
}


================================================
FILE: gopls/internal/golang/assembly.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file produces the "Browse GOARCH assembly of f" HTML report.
//
// See also:
// - ./codeaction.go - computes the symbol and offers the CodeAction command.
// - ../server/command.go - handles the command by opening a web page.
// - ../server/server.go - handles the HTTP request and calls this function.
//
// For language-server behavior in Go assembly language files,
// see [golang.org/x/tools/gopls/internal/goasm].

import (
	"bytes"
	"context"
	"fmt"
	"html"
	"io"
	"net/http"
	"os"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/util/morestrings"
)

// AssemblyHTML returns an HTML document containing an assembly listing of the selected function.
//
// TODO(adonovan): cross-link jumps and block labels, like github.com/aclements/objbrowse.
//
// See gopls/internal/test/integration/misc/webserver_test.go for tests.
func AssemblyHTML(ctx context.Context, snapshot *cache.Snapshot, w http.ResponseWriter, pkg *cache.Package, symbol string, web Web) {
	// Prepare to compile the package with -S, and capture its stderr stream.
	// We use "go test -c" not "go build" as it covers all three packages
	// (p, "p [p.test]", "p_test [p.test]") in the directory, if they exist.
	// (See also compileropt.go.)
	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(cache.NoNetwork, pkg.Metadata().CompiledGoFiles[0].DirPath(),
		"test", []string{
			"-c",
			"-o", os.DevNull,
			"-gcflags=-S",
			".",
		})
	if err != nil {
		// e.g. failed to write overlays (rare)
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
	defer cleanupInvocation()

	escape := html.EscapeString

	// Emit the start of the report.
	titleHTML := fmt.Sprintf("%s assembly for %s",
		escape(snapshot.View().GOARCH()),
		escape(symbol))
	io.WriteString(w, `<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>`+titleHTML+`</title>
  <link rel="stylesheet" href="/assets/common.css">
  <script src="/assets/common.js"></script>
</head>
<body>
<h1>`+titleHTML+`</h1>
<p>
  <a href='https://go.dev/doc/asm'>A Quick Guide to Go's Assembler</a>
</p>
<p>
  Experimental. <a href='https://github.com/golang/go/issues/67478'>Contributions welcome!</a>
</p>
<p>
  Click on a source line marker <code>L1234</code> to navigate your editor there.
  (VS Code users: please upvote <a href='https://github.com/microsoft/vscode/issues/208093'>#208093</a>)
</p>
<p id='compiling'>Compiling...</p>
<pre>
`)
	if flusher, ok := w.(http.Flusher); ok {
		flusher.Flush()
	}

	// At this point errors must be reported by writing HTML.
	// To do this, set "status" return early.

	var buf bytes.Buffer
	status := "Reload the page to recompile."
	defer func() {
		// Update the "Compiling..." message.
		fmt.Fprintf(&buf, `
</pre>
<script>
document.getElementById('compiling').innerText = %q;
</script>
</body>`, status)
		w.Write(buf.Bytes())
	}()

	// Compile the package.
	_, stderr, err, _ := snapshot.View().GoCommandRunner().RunRaw(ctx, *inv)
	if err != nil {
		status = fmt.Sprintf("compilation failed: %v", err)
		return
	}

	// Write the rest of the report.
	content := stderr.String()

	// insnRx matches an assembly instruction line.
	// Submatch groups are: (offset-hex-dec, file-line-column, instruction).
	insnRx := regexp.MustCompile(`^(\s+0x[0-9a-f ]+)\(([^)]*)\)\s+(.*)$`)

	// Parse the functions of interest out of the listing.
	// Each function is of the form:
	//
	//     symbol STEXT k=v...
	//         0x0000 00000 (/file.go:123) NOP...
	//         ...
	//
	// Allow matches of symbol, symbol.func1, symbol.deferwrap, etc.
	on := false
	for line := range strings.SplitSeq(content, "\n") {
		// start of function symbol?
		if strings.Contains(line, " STEXT ") {
			on = strings.HasPrefix(line, symbol) &&
				(line[len(symbol)] == ' ' || line[len(symbol)] == '.')
		}
		if !on {
			continue // within uninteresting symbol
		}

		// In lines of the form
		//   "\t0x0000 00000 (/file.go:123) NOP..."
		// replace the "(/file.go:123)" portion with an "L0123" source link.
		// Skip filenames of the form "<foo>".
		if parts := insnRx.FindStringSubmatch(line); parts != nil {
			link := "     " // if unknown
			if file, linenum, ok := morestrings.CutLast(parts[2], ":"); ok && !strings.HasPrefix(file, "<") {
				if linenum, err := strconv.Atoi(linenum); err == nil {
					text := fmt.Sprintf("L%04d", linenum)
					link = sourceLink(text, web.SrcURL(file, linenum, 1))
				}
			}
			fmt.Fprintf(&buf, "%s\t%s\t%s", escape(parts[1]), link, escape(parts[3]))
		} else {
			buf.WriteString(escape(line))
		}
		buf.WriteByte('\n')
	}
}


================================================
FILE: gopls/internal/golang/call_hierarchy.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/types"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typesinternal"
)

// PrepareCallHierarchy returns an array of CallHierarchyItem for a file and the position within the file.
func PrepareCallHierarchy(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.CallHierarchyItem, error) {
	ctx, done := event.Start(ctx, "golang.PrepareCallHierarchy")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	obj, err := callHierarchyFuncAtRange(pkg.TypesInfo(), pgf, astutil.RangeOf(start, end))
	if err != nil {
		return nil, err
	}
	declLoc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, obj)
	if err != nil {
		return nil, err
	}

	return []protocol.CallHierarchyItem{{
		Name:           obj.Name(),
		Kind:           protocol.Function,
		Tags:           []protocol.SymbolTag{},
		Detail:         callHierarchyItemDetail(obj, declLoc),
		URI:            declLoc.URI,
		Range:          declLoc.Range,
		SelectionRange: declLoc.Range,
	}}, nil
}

// IncomingCalls returns an array of CallHierarchyIncomingCall for a file and the position within the file.
func IncomingCalls(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.CallHierarchyIncomingCall, error) {
	ctx, done := event.Start(ctx, "golang.IncomingCalls")
	defer done()

	refs, err := references(ctx, snapshot, fh, rng, false)
	if err != nil {
		if errors.Is(err, ErrNoIdentFound) || errors.Is(err, errNoObjectFound) {
			return nil, nil
		}
		return nil, err
	}

	// Group references by their enclosing function declaration.
	incomingCalls := make(map[protocol.Location]*protocol.CallHierarchyIncomingCall)
	for _, ref := range refs {
		callItem, err := enclosingNodeCallItem(ctx, snapshot, ref.pkgPath, ref.location)
		if err != nil {
			event.Error(ctx, fmt.Sprintf("error getting enclosing node for %q", ref.pkgPath), err)
			continue
		}
		loc := callItem.URI.Location(callItem.Range)
		call, ok := incomingCalls[loc]
		if !ok {
			call = &protocol.CallHierarchyIncomingCall{From: callItem}
			incomingCalls[loc] = call
		}
		call.FromRanges = append(call.FromRanges, ref.location.Range)
	}

	// Flatten the map of pointers into a slice of values.
	incomingCallItems := make([]protocol.CallHierarchyIncomingCall, 0, len(incomingCalls))
	for _, callItem := range moremaps.SortedFunc(incomingCalls, protocol.CompareLocation) {
		incomingCallItems = append(incomingCallItems, *callItem)
	}
	return incomingCallItems, nil
}

// enclosingNodeCallItem creates a CallHierarchyItem representing the function call at loc.
func enclosingNodeCallItem(ctx context.Context, snapshot *cache.Snapshot, pkgPath PackagePath, loc protocol.Location) (protocol.CallHierarchyItem, error) {
	// Parse the file containing the reference.
	fh, err := snapshot.ReadFile(ctx, loc.URI)
	if err != nil {
		return protocol.CallHierarchyItem{}, err
	}
	// TODO(adonovan): opt: before parsing, trim the bodies of functions
	// that don't contain the reference, using either a scanner-based
	// implementation such as https://go.dev/play/p/KUrObH1YkX8
	// (~31% speedup), or a byte-oriented implementation (2x speedup).
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return protocol.CallHierarchyItem{}, err
	}
	start, end, err := pgf.RangePos(loc.Range)
	if err != nil {
		return protocol.CallHierarchyItem{}, err
	}

	// Find the enclosing named function, if any.
	//
	// It is tempting to treat anonymous functions as nodes in the
	// call hierarchy, and historically we used to do that,
	// poorly; see #64451. However, it is impossible to track
	// references to anonymous functions without much deeper
	// analysis. Local analysis is tractable, but ultimately it
	// can only detect calls from the outer function to the inner
	// function.
	//
	// It is simpler and clearer to treat the top-level named
	// function and all its nested functions as one entity, and it
	// allows users to recursively expand the tree where, before,
	// the chain would be broken by each lambda.
	//
	// If the selection is in a global var initializer,
	// default to the file's package declaration.
	path, _ := goastutil.PathEnclosingInterval(pgf.File, start, end)
	var (
		name = pgf.File.Name.Name
		kind = protocol.Package
	)
	start, end = pgf.File.Name.Pos(), pgf.File.Name.End()
	for _, node := range path {
		switch node := node.(type) {
		case *ast.FuncDecl:
			name = node.Name.Name
			start, end = node.Name.Pos(), node.Name.End()
			kind = protocol.Function

		case *ast.FuncLit:
			// If the call comes from a FuncLit with
			// no enclosing FuncDecl, then use the
			// FuncLit's extent.
			name = "func"
			start, end = node.Pos(), node.Type.End() // signature, sans body
			kind = protocol.Function

		case *ast.ValueSpec:
			// If the call comes from a var (or,
			// theoretically, const) initializer outside
			// any function, then use the ValueSpec.Names span.
			name = "init"
			start, end = node.Names[0].Pos(), node.Names[len(node.Names)-1].End()
			kind = protocol.Variable
		}
	}

	rng, err := pgf.PosRange(start, end)
	if err != nil {
		return protocol.CallHierarchyItem{}, err
	}

	return protocol.CallHierarchyItem{
		Name:           name,
		Kind:           kind,
		Tags:           []protocol.SymbolTag{},
		Detail:         fmt.Sprintf("%s • %s", pkgPath, fh.URI().Base()),
		URI:            loc.URI,
		Range:          rng,
		SelectionRange: rng,
	}, nil
}

// OutgoingCalls returns an array of CallHierarchyOutgoingCall for a file and the position within the file.
func OutgoingCalls(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, pp protocol.Position) ([]protocol.CallHierarchyOutgoingCall, error) {
	ctx, done := event.Start(ctx, "golang.OutgoingCalls")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	pos, err := pgf.PositionPos(pp)
	if err != nil {
		return nil, err
	}
	obj, err := callHierarchyFuncAtRange(pkg.TypesInfo(), pgf, astutil.RangeOf(pos, pos))
	if err != nil {
		return nil, err
	}
	if isBuiltin(obj) {
		return nil, nil // built-in functions have no outgoing calls
	}

	declPkg, declPGF, declPos, err := NarrowestDeclaringPackage(ctx, snapshot, pkg, obj)
	if err != nil {
		return nil, err
	}

	declNode, _, _ := findDeclInfo([]*ast.File{declPGF.File}, declPos)
	if declNode == nil {
		// TODO(rfindley): why don't we return an error here, or even bug.Errorf?
		return nil, nil
		// return nil, bug.Errorf("failed to find declaration for %v", obj)
	}

	// Find calls to known functions/methods,
	// including interface methods, and built-ins.
	var callRanges []astutil.Range
	for n := range ast.Preorder(declNode) {
		if call, ok := n.(*ast.CallExpr); ok {
			callee := typeutil.Callee(pkg.TypesInfo(), call)
			switch callee.(type) {
			case *types.Func, *types.Builtin:
				// Skip trivial builtins (e.g. len)
				// but allow unsafe.Slice, etc.
				if callee.Pkg() == nil {
					continue
				}
				id := typesinternal.UsedIdent(pkg.TypesInfo(), call.Fun)
				callRanges = append(callRanges, astutil.RangeOf(id.Pos(), id.End()))
			}
		}
	}

	outgoingCalls := make(map[protocol.Location]*protocol.CallHierarchyOutgoingCall)
	for _, callRange := range callRanges {
		obj, err := callHierarchyFuncAtRange(declPkg.TypesInfo(), declPGF, callRange)
		if err != nil {
			continue // ignore
		}

		loc, err := ObjectLocation(ctx, declPkg.FileSet(), snapshot, obj)
		if err != nil {
			return nil, err
		}

		outgoingCall, ok := outgoingCalls[loc]
		if !ok {
			outgoingCall = &protocol.CallHierarchyOutgoingCall{
				To: protocol.CallHierarchyItem{
					Name:           obj.Name(),
					Kind:           protocol.Function,
					Tags:           []protocol.SymbolTag{},
					Detail:         callHierarchyItemDetail(obj, loc),
					URI:            loc.URI,
					Range:          loc.Range,
					SelectionRange: loc.Range,
				},
			}
			outgoingCalls[loc] = outgoingCall
		}

		rng, err := declPGF.PosRange(callRange.Pos(), callRange.End())
		if err != nil {
			return nil, err
		}
		outgoingCall.FromRanges = append(outgoingCall.FromRanges, rng)
	}

	outgoingCallItems := make([]protocol.CallHierarchyOutgoingCall, 0, len(outgoingCalls))
	for _, callItem := range moremaps.SortedFunc(outgoingCalls, protocol.CompareLocation) {
		outgoingCallItems = append(outgoingCallItems, *callItem)
	}
	return outgoingCallItems, nil
}

func callHierarchyItemDetail(obj types.Object, loc protocol.Location) string {
	detail := loc.URI.Base()
	if obj.Pkg() != nil {
		detail = fmt.Sprintf("%s • %s", obj.Pkg().Path(), detail)
	}
	return detail
}

// callHierarchyFuncAtRange returns the function symbol (Func or Builtin) referred
// to by the identifier at the specified range.
func callHierarchyFuncAtRange(info *types.Info, pgf *parsego.File, rng astutil.Range) (types.Object, error) {
	cur, ok := pgf.Cursor().FindByPos(rng.Pos(), rng.End())
	if !ok {
		return nil, fmt.Errorf("no enclosing syntax") // can't happen
	}
	id, ok := cur.Node().(*ast.Ident)
	if !ok {
		return nil, fmt.Errorf("identifier not found")
	}
	switch obj := info.ObjectOf(id).(type) {
	case *types.Func, *types.Builtin:
		return obj, nil
	case nil:
		return nil, fmt.Errorf("no symbol here")
	default:
		return nil, fmt.Errorf("%s is not a function", obj.Name())
	}
}


================================================
FILE: gopls/internal/golang/change_quote.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"go/ast"
	"go/token"
	"strconv"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/diff"
)

// convertStringLiteral reports whether we can convert between raw and interpreted
// string literals in the [start, end) range, along with a CodeAction containing the edits.
//
// Only the following conditions are true, the action in result is valid
//   - [start, end) is enclosed by a string literal
//   - if the string is interpreted string, need check whether the convert is allowed
func convertStringLiteral(req *codeActionsRequest) {
	path, _ := astutil.PathEnclosingInterval(req.pgf.File, req.start, req.end)
	lit, ok := path[0].(*ast.BasicLit)
	if !ok || lit.Kind != token.STRING {
		return
	}

	str, err := strconv.Unquote(lit.Value)
	if err != nil {
		return
	}

	interpreted := lit.Value[0] == '"'
	// Not all "..." strings can be represented as `...` strings.
	if interpreted && !strconv.CanBackquote(strings.ReplaceAll(str, "\n", "")) {
		return
	}

	var (
		title   string
		newText string
	)
	if interpreted {
		title = "Convert to raw string literal"
		newText = "`" + str + "`"
	} else {
		title = "Convert to interpreted string literal"
		newText = strconv.Quote(str)
	}

	start, end, err := safetoken.Offsets(req.pgf.Tok, lit.Pos(), lit.End())
	if err != nil {
		bug.Reportf("failed to get string literal offset by token.Pos:%v", err)
		return
	}
	edits := []diff.Edit{{
		Start: start,
		End:   end,
		New:   newText,
	}}
	textedits, err := protocol.EditsFromDiffEdits(req.pgf.Mapper, edits)
	if err != nil {
		bug.Reportf("failed to convert diff.Edit to protocol.TextEdit:%v", err)
		return
	}
	req.addEditAction(title, nil, protocol.DocumentChangeEdit(req.fh, textedits))
}


================================================
FILE: gopls/internal/golang/change_signature.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"regexp"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/imports"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/refactor/inline"
	"golang.org/x/tools/internal/typesinternal"
)

// Changing a signature works as follows, supposing we have the following
// original function declaration:
//
//  func Foo(a, b, c int)
//
// Step 1: Write the declaration according to the given signature change. For
// example, given the parameter transformation [2, 0, 1], we construct a new
// ast.FuncDecl for the signature:
//
//   func Foo0(c, a, b int)
//
// Step 2: Build a wrapper function that delegates to the new function.
// With this example, the wrapper would look like this:
//
//   func Foo1(a, b, c int) {
//     Foo0(c, a, b int)
//   }
//
// Step 3: Swap in the wrapper for the original, and inline all calls. The
// trick here is to rename Foo1 to Foo, inline all calls (replacing them with
// a call to Foo0), and then rename Foo0 back to Foo, using a simple string
// replacement.
//
// For example, given a call
//
// 	func _() {
// 		Foo(1, 2, 3)
// 	}
//
// The inlining results in
//
// 	func _() {
// 		Foo0(3, 1, 2)
// 	}
//
// And then renaming results in
//
// 	func _() {
//  	Foo(3, 1, 2)
// 	}
//
// And the desired signature rewriting has occurred! Note: in practice, we
// don't use the names Foo0 and Foo1, as they are too likely to conflict with
// an existing declaration name. (Instead, we use the prefix G_o_ + p_l_s)
//
// The advantage of going through the inliner is that we get all of the
// semantic considerations for free: the inliner will check for side effects
// of arguments, check if the last use of a variable is being removed, check
// for unnecessary imports, etc.
//
// Furthermore, by running the change signature rewriting through the inliner,
// we ensure that the inliner gets better to the point that it can handle a
// change signature rewrite just as well as if we had implemented change
// signature as its own operation. For example, suppose we support reordering
// the results of a function. In that case, the wrapper would be:
//
// 	func Foo1() (int, int) {
// 		y, x := Foo0()
// 		return x, y
// 	}
//
// And a call would be rewritten from
//
// 	x, y := Foo()
//
// To
//
//  r1, r2 := Foo()
//  x, y := r2, r1
//
// In order to make this idiomatic, we'd have to teach the inliner to rewrite
// this as y, x := Foo(). The simplest and most general way to achieve this is
// to teach the inliner to recognize when a variable is redundant (r1 and r2,
// in this case), lifting declarations. That's probably a very useful skill for
// the inliner to have.

// removeParam computes a refactoring to remove the parameter indicated by the
// given range.
func removeParam(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.DocumentChange, error) {
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	// Find the unused parameter to remove.
	info := findParam(pgf, rng)
	if info == nil || info.paramIndex == -1 {
		return nil, fmt.Errorf("no param found")
	}
	// Write a transformation to remove the param.
	var newParams []int
	for i := 0; i < info.decl.Type.Params.NumFields(); i++ {
		if i != info.paramIndex {
			newParams = append(newParams, i)
		}
	}
	return ChangeSignature(ctx, snapshot, pkg, pgf, rng, newParams)
}

// ChangeSignature computes a refactoring to update the signature according to
// the provided parameter transformation, for the signature definition
// surrounding rng.
//
// newParams expresses the new parameters for the signature in terms of the old
// parameters. Each entry in newParams is the index of the new parameter in the
// original parameter list. For example, given func Foo(a, b, c int) and newParams
// [2, 0, 1], the resulting changed signature is Foo(c, a, b int). If newParams
// omits an index of the original signature, that parameter is removed.
//
// This operation is a work in progress. Remaining TODO:
//   - Handle adding parameters.
//   - Handle adding/removing/reordering results.
//   - Improve the extra newlines in output.
//   - Stream type checking via ForEachPackage.
//   - Avoid unnecessary additional type checking.
func ChangeSignature(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, rng protocol.Range, newParams []int) ([]protocol.DocumentChange, error) {
	// Changes to our heuristics for whether we can remove a parameter must also
	// be reflected in the canRemoveParameter helper.
	if perrors, terrors := pkg.ParseErrors(), pkg.TypeErrors(); len(perrors) > 0 || len(terrors) > 0 {
		var sample string
		if len(perrors) > 0 {
			sample = perrors[0].Error()
		} else {
			sample = terrors[0].Error()
		}
		return nil, fmt.Errorf("can't change signatures for packages with parse or type errors: (e.g. %s)", sample)
	}

	info := findParam(pgf, rng)
	if info == nil || info.decl == nil {
		return nil, fmt.Errorf("failed to find declaration")
	}

	// Step 1: create the new declaration, which is a copy of the original decl
	// with the rewritten signature.

	// Flatten, transform and regroup fields, using the flatField intermediate
	// representation. A flatField is the result of flattening an *ast.FieldList
	// along with type information.
	type flatField struct {
		name     string // empty if the field is unnamed
		typeExpr ast.Expr
		typ      types.Type
	}

	var newParamFields []flatField
	for id, field := range astutil.FlatFields(info.decl.Type.Params) {
		typ := pkg.TypesInfo().TypeOf(field.Type)
		if typ == nil {
			return nil, fmt.Errorf("missing field type for field #%d", len(newParamFields))
		}
		field := flatField{
			typeExpr: field.Type,
			typ:      typ,
		}
		if id != nil {
			field.name = id.Name
		}
		newParamFields = append(newParamFields, field)
	}

	// Select the new parameter fields.
	newParamFields, ok := selectElements(newParamFields, newParams)
	if !ok {
		return nil, fmt.Errorf("failed to apply parameter transformation %v", newParams)
	}

	// writeFields performs the regrouping of named fields.
	writeFields := func(flatFields []flatField) *ast.FieldList {
		list := new(ast.FieldList)
		for i, f := range flatFields {
			var field *ast.Field
			if i > 0 && f.name != "" && flatFields[i-1].name != "" && types.Identical(f.typ, flatFields[i-1].typ) {
				// Group named fields if they have the same type.
				field = list.List[len(list.List)-1]
			} else {
				// Otherwise, create a new field.
				field = &ast.Field{
					Type: astutil.CloneNode(f.typeExpr),
				}
				list.List = append(list.List, field)
			}
			if f.name != "" {
				field.Names = append(field.Names, ast.NewIdent(f.name))
			}
		}
		return list
	}

	newDecl := astutil.CloneNode(info.decl)
	newDecl.Type.Params = writeFields(newParamFields)

	// Step 2: build a wrapper function calling the new declaration.

	var (
		params   = astutil.CloneNode(info.decl.Type.Params) // parameters of wrapper func: "_" names must be modified
		args     = make([]ast.Expr, len(newParams))         // arguments to the delegated call
		variadic = false                                    // whether the signature is variadic
	)
	{
		// Record names used by non-blank parameters, just in case the user had a
		// parameter named 'blank0', which would conflict with the synthetic names
		// we construct below.
		// TODO(rfindley): add an integration test for this behavior.
		nonBlankNames := make(map[string]bool) // for detecting conflicts with renamed blanks
		for _, fld := range params.List {
			for _, n := range fld.Names {
				if n.Name != "_" {
					nonBlankNames[n.Name] = true
				}
			}
			if len(fld.Names) == 0 {
				// All parameters must have a non-blank name. For convenience, give
				// this field a blank name.
				fld.Names = append(fld.Names, ast.NewIdent("_")) // will be named below
			}
		}
		// oldParams maps parameters to their argument in the delegated call.
		// In other words, it is the inverse of newParams, but it is represented as
		// a map rather than a slice, as not every old param need exist in
		// newParams.
		oldParams := make(map[int]int)
		for new, old := range newParams {
			oldParams[old] = new
		}
		blanks := 0
		paramIndex := 0 // global param index.
		for id, field := range astutil.FlatFields(params) {
			argIndex, ok := oldParams[paramIndex]
			paramIndex++
			if !ok {
				continue // parameter is removed
			}
			if id.Name == "_" { // from above: every field has names
				// Create names for blank (_) parameters so the delegating wrapper
				// can refer to them.
				for {
					// These names will not be seen by the user, so give them an
					// arbitrary name.
					newName := fmt.Sprintf("blank%d", blanks)
					blanks++
					if !nonBlankNames[newName] {
						id.Name = newName
						break
					}
				}
			}
			args[argIndex] = ast.NewIdent(id.Name)
			// Record whether the call has an ellipsis.
			// (Only the last loop iteration matters.)
			_, variadic = field.Type.(*ast.Ellipsis)
		}
	}

	// Step 3: Rewrite all referring calls, by swapping in the wrapper and
	// inlining all.

	newContent, err := rewriteCalls(ctx, signatureRewrite{
		snapshot: snapshot,
		pkg:      pkg,
		pgf:      pgf,
		origDecl: info.decl,
		newDecl:  newDecl,
		params:   params,
		callArgs: args,
		variadic: variadic,
	})
	if err != nil {
		return nil, err
	}

	// Finally, rewrite the original declaration. We do this after inlining all
	// calls, as there may be calls in the same file as the declaration. But none
	// of the inlining should have changed the location of the original
	// declaration.
	{
		idx := findDecl(pgf.File, info.decl)
		if idx < 0 {
			return nil, bug.Errorf("didn't find original decl")
		}

		src, ok := newContent[pgf.URI]
		if !ok {
			src = pgf.Src
		}
		fset := tokeninternal.FileSetFor(pgf.Tok)
		src, err := rewriteSignature(fset, idx, src, newDecl)
		if err != nil {
			return nil, err
		}
		newContent[pgf.URI] = src
	}

	// Translate the resulting state into document changes.
	var changes []protocol.DocumentChange
	for uri, after := range newContent {
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		before, err := fh.Content()
		if err != nil {
			return nil, err
		}
		edits := diff.Bytes(before, after)
		mapper := protocol.NewMapper(uri, before)
		textedits, err := protocol.EditsFromDiffEdits(mapper, edits)
		if err != nil {
			return nil, fmt.Errorf("computing edits for %s: %v", uri, err)
		}
		change := protocol.DocumentChangeEdit(fh, textedits)
		changes = append(changes, change)
	}
	return changes, nil
}

// rewriteSignature rewrites the signature of the declIdx'th declaration in src
// to use the signature of newDecl (described by fset).
//
// TODO(rfindley): I think this operation could be generalized, for example by
// using a concept of a 'nodepath' to correlate nodes between two related
// files.
//
// Note that with its current application, rewriteSignature is expected to
// succeed. Separate bug.Errorf calls are used below (rather than one call at
// the callsite) in order to have greater precision.
func rewriteSignature(fset *token.FileSet, declIdx int, src0 []byte, newDecl *ast.FuncDecl) ([]byte, error) {
	// Parse the new file0 content, to locate the original params.
	file0, err := parser.ParseFile(fset, "", src0, parser.ParseComments|parser.SkipObjectResolution)
	if err != nil {
		return nil, bug.Errorf("re-parsing declaring file failed: %v", err)
	}
	decl0, _ := file0.Decls[declIdx].(*ast.FuncDecl)
	// Inlining shouldn't have changed the location of any declarations, but do
	// a sanity check.
	if decl0 == nil || decl0.Name.Name != newDecl.Name.Name {
		return nil, bug.Errorf("inlining affected declaration order: found %v, not func %s", decl0, newDecl.Name.Name)
	}
	opening0, closing0, err := safetoken.Offsets(fset.File(decl0.Pos()), decl0.Type.Params.Opening, decl0.Type.Params.Closing)
	if err != nil {
		return nil, bug.Errorf("can't find params: %v", err)
	}

	// Format the modified signature and apply a textual replacement. This
	// minimizes comment disruption.
	formattedType := FormatNode(fset, newDecl.Type)
	expr, err := parser.ParseExprFrom(fset, "", []byte(formattedType), 0)
	if err != nil {
		return nil, bug.Errorf("parsing modified signature: %v", err)
	}
	newType := expr.(*ast.FuncType)
	opening1, closing1, err := safetoken.Offsets(fset.File(newType.Pos()), newType.Params.Opening, newType.Params.Closing)
	if err != nil {
		return nil, bug.Errorf("param offsets: %v", err)
	}
	newParams := formattedType[opening1 : closing1+1]

	// Splice.
	var buf bytes.Buffer
	buf.Write(src0[:opening0])
	buf.WriteString(newParams)
	buf.Write(src0[closing0+1:])
	newSrc := buf.Bytes()
	if len(file0.Imports) > 0 {
		formatted, err := imports.Process("output", newSrc, nil)
		if err != nil {
			return nil, bug.Errorf("imports.Process failed: %v", err)
		}
		newSrc = formatted
	}
	return newSrc, nil
}

// paramInfo records information about a param identified by a position.
type paramInfo struct {
	decl       *ast.FuncDecl // enclosing func decl (non-nil)
	paramIndex int           // index of param among all params, or -1
	field      *ast.Field    // enclosing field of Decl, or nil if range not among parameters
	name       *ast.Ident    // indicated name (either enclosing, or Field.Names[0] if len(Field.Names) == 1)
}

// findParam finds the parameter information spanned by the given range.
func findParam(pgf *parsego.File, rng protocol.Range) *paramInfo {
	info := paramInfo{paramIndex: -1}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil
	}

	path, _ := goastutil.PathEnclosingInterval(pgf.File, start, end)
	var (
		id    *ast.Ident
		field *ast.Field
	)
	// Find the outermost enclosing node of each kind, whether or not they match
	// the semantics described in the docstring.
	for _, n := range path {
		switch n := n.(type) {
		case *ast.Ident:
			id = n
		case *ast.Field:
			field = n
		case *ast.FuncDecl:
			info.decl = n
		}
	}
	if info.decl == nil {
		return nil
	}
	if field == nil {
		return &info
	}
	pi := 0
	// Search for field and id among parameters of decl.
	// This search may fail, even if one or both of id and field are non nil:
	// field could be from a result or local declaration, and id could be part of
	// the field type rather than names.
	for _, f := range info.decl.Type.Params.List {
		if f == field {
			info.paramIndex = pi // may be modified later
			info.field = f
			for _, n := range f.Names {
				if n == id {
					info.paramIndex = pi
					info.name = n
					break
				}
				pi++
			}
			if info.name == nil && len(info.field.Names) == 1 {
				info.name = info.field.Names[0]
			}
			break
		} else {
			m := len(f.Names)
			if m == 0 {
				m = 1
			}
			pi += m
		}
	}
	return &info
}

// signatureRewrite defines a rewritten function signature.
//
// See rewriteCalls for more details.
type signatureRewrite struct {
	snapshot          *cache.Snapshot
	pkg               *cache.Package
	pgf               *parsego.File
	origDecl, newDecl *ast.FuncDecl
	params            *ast.FieldList
	callArgs          []ast.Expr
	variadic          bool
}

// rewriteCalls returns the document changes required to rewrite the
// signature of origDecl to that of newDecl.
//
// This is a rather complicated factoring of the rewrite operation, but is able
// to describe arbitrary rewrites. Specifically, rewriteCalls creates a
// synthetic copy of pkg, where the original function declaration is changed to
// be a trivial wrapper around the new declaration. params and callArgs are
// used to perform this delegation: params must have the same type as origDecl,
// but may have renamed parameters (such as is required for delegating blank
// parameters). callArgs are the arguments of the delegated call (i.e. using
// params).
//
// For example, consider removing the unused 'b' parameter below, rewriting
//
//	func Foo(a, b, c, _ int) int {
//	  return a+c
//	}
//
// To
//
//	func Foo(a, c, _ int) int {
//	  return a+c
//	}
//
// In this case, rewriteCalls is parameterized as follows:
//   - origDecl is the original declaration
//   - newDecl is the new declaration, which is a copy of origDecl less the 'b'
//     parameter.
//   - params is a new parameter list (a, b, c, blank0 int) to be used for the
//     new wrapper.
//   - callArgs is the argument list (a, c, blank0), to be used to call the new
//     delegate.
//
// rewriting is expressed this way so that rewriteCalls can own the details
// of *how* this rewriting is performed. For example, as of writing it names
// the synthetic delegate G_o_p_l_s_foo, but the caller need not know this.
//
// By passing an entirely new declaration, rewriteCalls may be used for
// signature refactorings that may affect the function body, such as removing
// or adding return values.
func rewriteCalls(ctx context.Context, rw signatureRewrite) (map[protocol.DocumentURI][]byte, error) {
	// tag is a unique prefix that is added to the delegated declaration.
	//
	// It must have a ~0% probability of causing collisions with existing names.
	const tag = "G_o_p_l_s_"

	var (
		modifiedSrc  []byte
		modifiedFile *ast.File
		modifiedDecl *ast.FuncDecl
	)
	{
		delegate := astutil.CloneNode(rw.newDecl) // clone before modifying
		delegate.Name.Name = tag + delegate.Name.Name
		if obj := rw.pkg.Types().Scope().Lookup(delegate.Name.Name); obj != nil {
			return nil, fmt.Errorf("synthetic name %q conflicts with an existing declaration", delegate.Name.Name)
		}

		wrapper := astutil.CloneNode(rw.origDecl)
		wrapper.Type.Params = rw.params

		// Get the receiver name, creating it if necessary.
		var recv string // nonempty => call is a method call with receiver recv
		if wrapper.Recv.NumFields() > 0 {
			if len(wrapper.Recv.List[0].Names) > 0 {
				recv = wrapper.Recv.List[0].Names[0].Name
			} else {
				// Create unique name for the temporary receiver, which will be inlined away.
				//
				// We use the lexical scope of the original function to avoid conflicts
				// with (e.g.) named result variables. However, since the parameter syntax
				// may have been modified/renamed from the original function, we must
				// reject those names too.
				usedParams := make(map[string]bool)
				for _, fld := range wrapper.Type.Params.List {
					for _, name := range fld.Names {
						usedParams[name.Name] = true
					}
				}
				scope := rw.pkg.TypesInfo().Scopes[rw.origDecl.Type]
				if scope == nil {
					return nil, bug.Errorf("missing function scope for %v", rw.origDecl.Name.Name)
				}
				for i := 0; ; i++ {
					recv = fmt.Sprintf("r%d", i)
					_, obj := scope.LookupParent(recv, token.NoPos)
					if obj == nil && !usedParams[recv] {
						break
					}
				}
				wrapper.Recv.List[0].Names = []*ast.Ident{{Name: recv}}
			}
		}

		name := &ast.Ident{Name: delegate.Name.Name}
		var fun ast.Expr = name
		if recv != "" {
			fun = &ast.SelectorExpr{
				X:   &ast.Ident{Name: recv},
				Sel: name,
			}
		}
		call := &ast.CallExpr{
			Fun:  fun,
			Args: rw.callArgs,
		}
		if rw.variadic {
			call.Ellipsis = 1 // must not be token.NoPos
		}

		var stmt ast.Stmt
		if delegate.Type.Results.NumFields() > 0 {
			stmt = &ast.ReturnStmt{
				Results: []ast.Expr{call},
			}
		} else {
			stmt = &ast.ExprStmt{
				X: call,
			}
		}
		wrapper.Body = &ast.BlockStmt{
			List: []ast.Stmt{stmt},
		}

		fset := tokeninternal.FileSetFor(rw.pgf.Tok)
		var err error
		modifiedSrc, err = replaceFileDecl(rw.pgf, rw.origDecl, delegate)
		if err != nil {
			return nil, err
		}
		// TODO(rfindley): we can probably get away with one fewer parse operations
		// by returning the modified AST from replaceDecl. Investigate if that is
		// accurate.
		modifiedSrc = append(modifiedSrc, []byte("\n\n"+FormatNode(fset, wrapper))...)
		modifiedFile, err = parser.ParseFile(rw.pkg.FileSet(), rw.pgf.URI.Path(), modifiedSrc, parser.ParseComments|parser.SkipObjectResolution)
		if err != nil {
			return nil, err
		}
		modifiedDecl = modifiedFile.Decls[len(modifiedFile.Decls)-1].(*ast.FuncDecl)
	}

	// Type check pkg again with the modified file, to compute the synthetic
	// callee.
	logf := logger(ctx, "change signature", rw.snapshot.Options().VerboseOutput)
	pkg2, info, err := reTypeCheck(logf, rw.pkg, map[protocol.DocumentURI]*ast.File{rw.pgf.URI: modifiedFile}, false)
	if err != nil {
		return nil, err
	}
	calleeInfo, err := inline.AnalyzeCallee(logf, rw.pkg.FileSet(), pkg2, info, modifiedDecl, modifiedSrc)
	if err != nil {
		return nil, fmt.Errorf("analyzing callee: %v", err)
	}

	post := func(got []byte) []byte { return bytes.ReplaceAll(got, []byte(tag), nil) }
	opts := &inline.Options{
		Logf:          logf,
		IgnoreEffects: true,
	}
	return inlineAllCalls(ctx, rw.snapshot, rw.pkg, rw.pgf, rw.origDecl, calleeInfo, post, opts)
}

// reTypeCheck re-type checks orig with new file contents defined by fileMask.
//
// It expects that any newly added imports are already present in the
// transitive imports of orig.
//
// If expectErrors is true, reTypeCheck allows errors in the new package.
// TODO(rfindley): perhaps this should be a filter to specify which errors are
// acceptable.
func reTypeCheck(logf func(string, ...any), orig *cache.Package, fileMask map[protocol.DocumentURI]*ast.File, expectErrors bool) (*types.Package, *types.Info, error) {
	pkg := types.NewPackage(string(orig.Metadata().PkgPath), string(orig.Metadata().Name))
	info := &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		Scopes:       make(map[ast.Node]*types.Scope),
		Instances:    make(map[*ast.Ident]types.Instance),
		FileVersions: make(map[*ast.File]string),
	}
	{
		var files []*ast.File
		for _, pgf := range orig.CompiledGoFiles() {
			if mask, ok := fileMask[pgf.URI]; ok {
				files = append(files, mask)
			} else {
				files = append(files, pgf.File)
			}
		}

		// Implement a BFS for imports in the transitive package graph.
		//
		// Note that this only works if any newly added imports are expected to be
		// present among transitive imports. In general we cannot assume this to
		// be the case, but in the special case of removing a parameter it works
		// because any parameter types must be present in export data.
		var importer func(importPath string) (*types.Package, error)
		{
			var (
				importsByPath = make(map[string]*types.Package) // cached imports
				toSearch      = []*types.Package{orig.Types()}  // packages to search
				searched      = make(map[string]bool)           // path -> (false, if present in toSearch; true, if already searched)
			)
			importer = func(path string) (*types.Package, error) {
				if p, ok := importsByPath[path]; ok {
					return p, nil
				}
				for len(toSearch) > 0 {
					pkg := toSearch[0]
					toSearch = toSearch[1:]
					searched[pkg.Path()] = true
					for _, p := range pkg.Imports() {
						// TODO(rfindley): this is incorrect: p.Path() is a package path,
						// whereas path is an import path. We can fix this by reporting any
						// newly added imports from inlining, or by using the ImporterFrom
						// interface and package metadata.
						//
						// TODO(rfindley): can't the inliner also be wrong here? It's
						// possible that an import path means different things depending on
						// the location.
						importsByPath[p.Path()] = p
						if _, ok := searched[p.Path()]; !ok {
							searched[p.Path()] = false
							toSearch = append(toSearch, p)
						}
					}
					if p, ok := importsByPath[path]; ok {
						return p, nil
					}
				}
				return nil, fmt.Errorf("missing import")
			}
		}
		cfg := &types.Config{
			Sizes:    orig.Metadata().TypesSizes,
			Importer: ImporterFunc(importer),
		}

		// Copied from cache/check.go.
		// TODO(rfindley): factor this out and fix goVersionRx.
		// Set Go dialect.
		if module := orig.Metadata().Module; module != nil && module.GoVersion != "" {
			goVersion := "go" + module.GoVersion
			// types.NewChecker panics if GoVersion is invalid.
			// An unparsable mod file should probably stop us
			// before we get here, but double check just in case.
			if goVersionRx.MatchString(goVersion) {
				cfg.GoVersion = goVersion
			}
		}
		if expectErrors {
			cfg.Error = func(err error) {
				logf("re-type checking: expected error: %v", err)
			}
		}
		typesinternal.SetUsesCgo(cfg)
		checker := types.NewChecker(cfg, orig.FileSet(), pkg, info)
		if err := checker.Files(files); err != nil && !expectErrors {
			return nil, nil, fmt.Errorf("type checking rewritten package: %v", err)
		}
	}
	return pkg, info, nil
}

// TODO(golang/go#63472): this looks wrong with the new Go version syntax.
var goVersionRx = regexp.MustCompile(`^go([1-9][0-9]*)\.(0|[1-9][0-9]*)$`)

// selectElements returns a new array of elements of s indicated by the
// provided list of indices. It returns false if any index was out of bounds.
//
// For example, given the slice []string{"a", "b", "c", "d"}, the
// indices []int{3, 0, 1} results in the slice []string{"d", "a", "b"}.
func selectElements[T any](s []T, indices []int) ([]T, bool) {
	res := make([]T, len(indices))
	for i, index := range indices {
		if index < 0 || index >= len(s) {
			return nil, false
		}
		res[i] = s[index]
	}
	return res, true
}

// replaceFileDecl replaces old with new in the file described by pgf.
//
// TODO(rfindley): generalize, and combine with rewriteSignature.
func replaceFileDecl(pgf *parsego.File, old, new ast.Decl) ([]byte, error) {
	i := findDecl(pgf.File, old)
	if i == -1 {
		return nil, bug.Errorf("didn't find old declaration")
	}
	start, end, err := safetoken.Offsets(pgf.Tok, old.Pos(), old.End())
	if err != nil {
		return nil, err
	}
	var out bytes.Buffer
	out.Write(pgf.Src[:start])
	fset := tokeninternal.FileSetFor(pgf.Tok)
	if err := format.Node(&out, fset, new); err != nil {
		return nil, bug.Errorf("formatting new node: %v", err)
	}
	out.Write(pgf.Src[end:])
	return out.Bytes(), nil
}

// findDecl finds the index of decl in file.Decls.
//
// TODO: use slices.Index when it is available.
func findDecl(file *ast.File, decl ast.Decl) int {
	for i, d := range file.Decls {
		if d == decl {
			return i
		}
	}
	return -1
}


================================================
FILE: gopls/internal/golang/code_lens.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"go/ast"
	"go/token"
	"go/types"
	"regexp"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
)

// CodeLensSources returns the supported sources of code lenses for Go files.
func CodeLensSources() map[settings.CodeLensSource]cache.CodeLensSourceFunc {
	return map[settings.CodeLensSource]cache.CodeLensSourceFunc{
		settings.CodeLensGenerate:      goGenerateCodeLens, // commands: Generate
		settings.CodeLensTest:          runTestCodeLens,    // commands: Test
		settings.CodeLensRegenerateCgo: regenerateCgoLens,  // commands: RegenerateCgo
	}
}

var (
	testRe      = regexp.MustCompile(`^Test([^a-z]|$)`) // TestFoo or Test but not Testable
	benchmarkRe = regexp.MustCompile(`^Benchmark([^a-z]|$)`)
)

func runTestCodeLens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	var codeLens []protocol.CodeLens

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	testFuncs, benchFuncs, err := testsAndBenchmarks(pkg.TypesInfo(), pgf)
	if err != nil {
		return nil, err
	}
	puri := fh.URI()
	for _, fn := range testFuncs {
		cmd := command.NewRunTestsCommand("run test", command.RunTestsArgs{
			URI:   puri,
			Tests: []string{fn.name},
		})
		rng := protocol.Range{Start: fn.rng.Start, End: fn.rng.Start}
		codeLens = append(codeLens, protocol.CodeLens{Range: rng, Command: cmd})
	}

	for _, fn := range benchFuncs {
		cmd := command.NewRunTestsCommand("run benchmark", command.RunTestsArgs{
			URI:        puri,
			Benchmarks: []string{fn.name},
		})
		rng := protocol.Range{Start: fn.rng.Start, End: fn.rng.Start}
		codeLens = append(codeLens, protocol.CodeLens{Range: rng, Command: cmd})
	}

	if len(benchFuncs) > 0 {
		pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
		if err != nil {
			return nil, err
		}
		// add a code lens to the top of the file which runs all benchmarks in the file
		rng, err := pgf.PosRange(pgf.File.Package, pgf.File.Package)
		if err != nil {
			return nil, err
		}
		var benches []string
		for _, fn := range benchFuncs {
			benches = append(benches, fn.name)
		}
		cmd := command.NewRunTestsCommand("run file benchmarks", command.RunTestsArgs{
			URI:        puri,
			Benchmarks: benches,
		})
		codeLens = append(codeLens, protocol.CodeLens{Range: rng, Command: cmd})
	}
	return codeLens, nil
}

type testFunc struct {
	name string
	rng  protocol.Range // of *ast.FuncDecl
}

// testsAndBenchmarks returns all Test and Benchmark functions in the
// specified file.
func testsAndBenchmarks(info *types.Info, pgf *parsego.File) (tests, benchmarks []testFunc, _ error) {
	if !strings.HasSuffix(pgf.URI.Path(), "_test.go") {
		return nil, nil, nil // empty
	}

	for _, d := range pgf.File.Decls {
		fn, ok := d.(*ast.FuncDecl)
		if !ok {
			continue
		}

		rng, err := pgf.NodeRange(fn)
		if err != nil {
			return nil, nil, err
		}

		if matchTestFunc(fn, info, testRe, "T") {
			tests = append(tests, testFunc{fn.Name.Name, rng})
		} else if matchTestFunc(fn, info, benchmarkRe, "B") {
			benchmarks = append(benchmarks, testFunc{fn.Name.Name, rng})
		}
	}
	return
}

func matchTestFunc(fn *ast.FuncDecl, info *types.Info, nameRe *regexp.Regexp, paramID string) bool {
	// Make sure that the function name matches a test function.
	if !nameRe.MatchString(fn.Name.Name) {
		return false
	}
	obj, ok := info.ObjectOf(fn.Name).(*types.Func)
	if !ok {
		return false
	}
	sig := obj.Signature()
	// Test functions should have only one parameter.
	if sig.Params().Len() != 1 {
		return false
	}

	// Check the type of the only parameter
	// (We don't Unalias or use typesinternal.ReceiverNamed
	// in the two checks below because "go test" can't see
	// through aliases when enumerating Test* functions;
	// it's syntactic.)
	paramTyp, ok := sig.Params().At(0).Type().(*types.Pointer)
	if !ok {
		return false
	}
	named, ok := paramTyp.Elem().(*types.Named)
	if !ok {
		return false
	}
	namedObj := named.Obj()
	if namedObj.Pkg().Path() != "testing" {
		return false
	}
	return namedObj.Id() == paramID
}

func goGenerateCodeLens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}
	const ggDirective = "//go:generate"
	for _, c := range pgf.File.Comments {
		for _, l := range c.List {
			if !strings.HasPrefix(l.Text, ggDirective) {
				continue
			}
			rng, err := pgf.PosRange(l.Pos(), l.Pos()+token.Pos(len(ggDirective)))
			if err != nil {
				return nil, err
			}
			dir := fh.URI().Dir()
			nonRecursiveCmd := command.NewGenerateCommand("run go generate", command.GenerateArgs{Dir: dir, Recursive: false})
			recursiveCmd := command.NewGenerateCommand("run go generate ./...", command.GenerateArgs{Dir: dir, Recursive: true})
			return []protocol.CodeLens{
				{Range: rng, Command: recursiveCmd},
				{Range: rng, Command: nonRecursiveCmd},
			}, nil

		}
	}
	return nil, nil
}

func regenerateCgoLens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}
	var c *ast.ImportSpec
	for _, imp := range pgf.File.Imports {
		if imp.Path.Value == `"C"` {
			c = imp
		}
	}
	if c == nil {
		return nil, nil
	}
	rng, err := pgf.NodeRange(c)
	if err != nil {
		return nil, err
	}
	puri := fh.URI()
	cmd := command.NewRegenerateCgoCommand("regenerate cgo definitions", command.URIArg{URI: puri})
	return []protocol.CodeLens{{Range: rng, Command: cmd}}, nil
}


================================================
FILE: gopls/internal/golang/codeaction.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"encoding/json"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"reflect"
	"slices"
	"strings"

	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/analysis/fillstruct"
	"golang.org/x/tools/gopls/internal/analysis/fillswitch"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang/stubmethods"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/typesinternal"
)

// CodeActions returns all enabled code actions (edits and other
// commands) available for the selected range.
//
// Depending on how the request was triggered, fewer actions may be
// offered, e.g. to avoid UI distractions after mere cursor motion.
//
// See ../protocol/codeactionkind.go for some code action theory.
func CodeActions(ctx context.Context, snapshot *cache.Snapshot, opts *settings.Options, fh file.Handle, rng protocol.Range, diagnostics []protocol.Diagnostic, enabled func(protocol.CodeActionKind) bool, trigger protocol.CodeActionTriggerKind) (actions []protocol.CodeAction, _ error) {
	loc := fh.URI().Location(rng)

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}

	// Scan to see if any enabled producer needs type information.
	var enabledMemo [len(codeActionProducers)]bool
	needTypes := false
	for i, p := range codeActionProducers {
		if enabled(p.kind) {
			enabledMemo[i] = true
			if p.needPkg {
				needTypes = true
			}
		}
	}

	// Compute type information if needed.
	// Also update pgf, start, end to be consistent with pkg.
	// They may differ in case of parse cache miss.
	var pkg *cache.Package
	if needTypes {
		var err error
		pkg, pgf, err = NarrowestPackageForFile(ctx, snapshot, loc.URI)
		if err != nil {
			return nil, err
		}
		start, end, err = pgf.RangePos(loc.Range)
		if err != nil {
			return nil, err
		}
	}

	// Execute each enabled producer function.
	req := &codeActionsRequest{
		actions:     &actions,
		lazy:        make(map[reflect.Type]any),
		snapshot:    snapshot,
		options:     *opts,
		fh:          fh,
		pgf:         pgf,
		loc:         loc,
		start:       start,
		end:         end,
		diagnostics: diagnostics,
		trigger:     trigger,
		pkg:         pkg,
	}
	for i, p := range codeActionProducers {
		if !enabledMemo[i] {
			continue
		}
		req.kind = p.kind
		if p.needPkg {
			req.pkg = pkg
		} else {
			req.pkg = nil
		}
		if err := p.fn(ctx, req); err != nil {
			// An error in one code action producer
			// should not affect the others.
			if ctx.Err() != nil {
				return nil, err
			}
			event.Error(ctx, fmt.Sprintf("CodeAction producer %s failed", p.kind), err)
			continue
		}
	}

	// Return code actions in the order their providers are listed.
	return actions, nil
}

// A codeActionsRequest is passed to each function
// that produces code actions.
type codeActionsRequest struct {
	// internal fields for use only by [CodeActions].
	actions *[]protocol.CodeAction // pointer to output slice; call addAction to populate
	lazy    map[reflect.Type]any   // lazy construction

	// inputs to the producer function:
	kind        protocol.CodeActionKind
	snapshot    *cache.Snapshot
	options     settings.Options
	fh          file.Handle
	pgf         *parsego.File
	loc         protocol.Location
	start, end  token.Pos
	diagnostics []protocol.Diagnostic
	trigger     protocol.CodeActionTriggerKind
	pkg         *cache.Package // set only if producer.needPkg
}

// addApplyFixAction adds an ApplyFix command-based CodeAction to the result.
func (req *codeActionsRequest) addApplyFixAction(title, fix string, loc protocol.Location) {
	cmd := command.NewApplyFixCommand(title, command.ApplyFixArgs{
		Fix:          fix,
		Location:     loc,
		ResolveEdits: req.resolveEdits(),
	})
	req.addCommandAction(cmd, true)
}

// addCommandAction adds a CodeAction to the result based on the provided command.
//
// If allowResolveEdits (and the client supports codeAction/resolve)
// then the command is embedded into the code action data field so
// that the client can later ask the server to "resolve" a command
// into an edit that they can preview and apply selectively.
// IMPORTANT: set allowResolveEdits only for actions that are 'edit aware',
// meaning they can detect when they are being executed in the context of a
// codeAction/resolve request, and return edits rather than applying them using
// workspace/applyEdit. In golang/go#71405, edits were being apply during the
// codeAction/resolve request handler.
// TODO(rfindley): refactor the command and code lens registration APIs so that
// resolve edit support is inferred from the command signature, not dependent
// on coordination between codeAction and command logic.
//
// Otherwise, the command is set as the code action operation.
func (req *codeActionsRequest) addCommandAction(cmd *protocol.Command, allowResolveEdits bool) {
	act := protocol.CodeAction{
		Title: cmd.Title,
		Kind:  req.kind,
	}
	if allowResolveEdits && req.resolveEdits() {
		data, err := json.Marshal(cmd)
		if err != nil {
			panic("unable to marshal")
		}
		msg := json.RawMessage(data)
		act.Data = &msg
	} else {
		act.Command = cmd
	}
	req.addAction(act)
}

// addEditAction adds an edit-based CodeAction to the result.
func (req *codeActionsRequest) addEditAction(title string, fixedDiagnostics []protocol.Diagnostic, changes ...protocol.DocumentChange) {
	req.addAction(protocol.CodeAction{
		Title:       title,
		Kind:        req.kind,
		Diagnostics: fixedDiagnostics,
		Edit:        protocol.NewWorkspaceEdit(changes...),
	})
}

// addAction adds a code action to the response.
func (req *codeActionsRequest) addAction(act protocol.CodeAction) {
	*req.actions = append(*req.actions, act)
}

// resolveEdits reports whether the client can resolve edits lazily.
func (req *codeActionsRequest) resolveEdits() bool {
	opts := req.snapshot.Options()
	return opts.CodeActionResolveOptions != nil &&
		slices.Contains(opts.CodeActionResolveOptions, "edit")
}

// lazyInit[*T](ctx, req) returns a pointer to an instance of T,
// calling new(T).init(ctx.req) on the first request.
//
// It is conceptually a (generic) method of req.
func lazyInit[P interface {
	init(ctx context.Context, req *codeActionsRequest)
	*T
}, T any](ctx context.Context, req *codeActionsRequest) P {
	t := reflect.TypeFor[T]()
	v, ok := req.lazy[t].(P)
	if !ok {
		v = new(T)
		v.init(ctx, req)
		req.lazy[t] = v
	}
	return v
}

// -- producers --

// A codeActionProducer describes a function that produces CodeActions
// of a particular kind.
// The function is only called if that kind is enabled.
type codeActionProducer struct {
	kind    protocol.CodeActionKind
	fn      func(ctx context.Context, req *codeActionsRequest) error
	needPkg bool // fn needs type information (req.pkg)
}

// Code Actions are returned in the order their producers are listed below.
// Depending on the client, this may influence the order they appear in the UI.
var codeActionProducers = [...]codeActionProducer{
	{kind: protocol.QuickFix, fn: quickFix, needPkg: true},
	{kind: protocol.SourceOrganizeImports, fn: sourceOrganizeImports},
	{kind: settings.AddTest, fn: addTest, needPkg: true},
	{kind: settings.GoAssembly, fn: goAssembly, needPkg: true},
	{kind: settings.GoDoc, fn: goDoc, needPkg: true},
	{kind: settings.GoFreeSymbols, fn: goFreeSymbols},
	{kind: settings.GoSplitPackage, fn: goSplitPackage, needPkg: true},
	{kind: settings.GoTest, fn: goTest, needPkg: true},
	{kind: settings.GoToggleCompilerOptDetails, fn: toggleCompilerOptDetails},
	{kind: settings.RefactorExtractFunction, fn: refactorExtractFunction},
	{kind: settings.RefactorExtractMethod, fn: refactorExtractMethod},
	{kind: settings.RefactorExtractToNewFile, fn: refactorExtractToNewFile},
	{kind: settings.RefactorExtractConstant, fn: refactorExtractVariable, needPkg: true},
	{kind: settings.RefactorExtractVariable, fn: refactorExtractVariable, needPkg: true},
	{kind: settings.RefactorExtractConstantAll, fn: refactorExtractVariableAll, needPkg: true},
	{kind: settings.RefactorExtractVariableAll, fn: refactorExtractVariableAll, needPkg: true},
	{kind: settings.RefactorInlineCall, fn: refactorInlineCall, needPkg: true},
	{kind: settings.RefactorInlineVariable, fn: refactorInlineVariable, needPkg: true},
	// {kind: settings.RefactorMoveType, fn: refactorMoveType, needPkg: true},
	{kind: settings.RefactorRewriteChangeQuote, fn: refactorRewriteChangeQuote},
	{kind: settings.RefactorRewriteFillStruct, fn: refactorRewriteFillStruct, needPkg: true},
	{kind: settings.RefactorRewriteFillSwitch, fn: refactorRewriteFillSwitch, needPkg: true},
	{kind: settings.RefactorRewriteInvertIf, fn: refactorRewriteInvertIf},
	{kind: settings.RefactorRewriteJoinLines, fn: refactorRewriteJoinLines, needPkg: true},
	{kind: settings.RefactorRewriteRemoveUnusedParam, fn: refactorRewriteRemoveUnusedParam, needPkg: true},
	{kind: settings.RefactorRewriteMoveParamLeft, fn: refactorRewriteMoveParamLeft, needPkg: true},
	{kind: settings.RefactorRewriteMoveParamRight, fn: refactorRewriteMoveParamRight, needPkg: true},
	{kind: settings.RefactorRewriteSplitLines, fn: refactorRewriteSplitLines, needPkg: true},
	{kind: settings.RefactorRewriteEliminateDotImport, fn: refactorRewriteEliminateDotImport, needPkg: true},
	{kind: settings.RefactorRewriteAddTags, fn: refactorRewriteAddStructTags, needPkg: true},
	{kind: settings.RefactorRewriteRemoveTags, fn: refactorRewriteRemoveStructTags, needPkg: true},
	{kind: settings.GoplsDocFeatures, fn: goplsDocFeatures}, // offer this one last (#72742)

	// Note: don't forget to update the allow-list in Server.CodeAction
	// when adding new query operations like GoTest and GoDoc that
	// are permitted even in generated source files.
}

// sourceOrganizeImports produces "Organize Imports" code actions.
func sourceOrganizeImports(ctx context.Context, req *codeActionsRequest) error {
	res := lazyInit[*allImportsFixesResult](ctx, req)

	// Send all of the import edits as one code action
	// if the file is being organized.
	if len(res.allFixEdits) > 0 {
		req.addEditAction("Organize Imports", nil, protocol.DocumentChangeEdit(req.fh, res.allFixEdits))
	}

	return nil
}

// quickFix produces code actions that fix errors,
// for example by adding/deleting/renaming imports,
// or declaring the missing methods of a type.
func quickFix(ctx context.Context, req *codeActionsRequest) error {
	// Only compute quick fixes if there are any diagnostics to fix.
	if len(req.diagnostics) == 0 {
		return nil
	}

	// Process any missing imports and pair them with the diagnostics they fix.
	res := lazyInit[*allImportsFixesResult](ctx, req)
	if res.err != nil {
		return nil
	}

	// Separate this into a set of codeActions per diagnostic, where
	// each action is the addition, removal, or renaming of one import.
	for _, importFix := range res.editsPerFix {
		fixedDiags := fixedByImportFix(importFix.fix, req.diagnostics)
		if len(fixedDiags) == 0 {
			continue
		}
		req.addEditAction(importFixTitle(importFix.fix), fixedDiags, protocol.DocumentChangeEdit(req.fh, importFix.edits))
	}

	// Quick fixes for type errors.
	info := req.pkg.TypesInfo()
	for _, typeError := range req.pkg.TypeErrors() {
		// Does type error overlap with CodeAction range?
		start, end := typeError.Pos, typeError.Pos
		if _, _, endPos, ok := typesinternal.ErrorCodeStartEnd(typeError); ok {
			end = endPos
		}
		typeErrorRange, err := req.pgf.PosRange(start, end)
		if err != nil || !protocol.Intersect(typeErrorRange, req.loc.Range) {
			continue
		}

		msg := typeError.Msg
		switch {
		// "Missing method" error? (stubmethods)
		// Offer a "Declare missing methods of INTERFACE" code action.
		// See [stubMissingInterfaceMethodsFixer] for command implementation.
		case strings.Contains(msg, "missing method"),
			strings.HasPrefix(msg, "cannot convert"),
			strings.Contains(msg, "not implement"):
			si := stubmethods.GetIfaceStubInfo(req.pkg.FileSet(), info, req.pgf, start, end)
			if si != nil {
				qual := typesinternal.FileQualifier(req.pgf.File, si.Concrete.Obj().Pkg())
				iface := types.TypeString(si.Interface.Type(), qual)
				msg := fmt.Sprintf("Declare missing methods of %s", iface)
				req.addApplyFixAction(msg, fixMissingInterfaceMethods, req.loc)
			}

		// "type X has no field or method Y" compiler error.
		// Offer a "Declare missing method T.f" code action.
		// See [stubMissingCalledFunctionFixer] for command implementation.
		case strings.Contains(msg, "has no field or method"):
			si := stubmethods.GetCallStubInfo(req.pkg.FileSet(), info, req.pgf, start, end)
			if si != nil {
				msg := fmt.Sprintf("Declare missing method %s.%s", si.Receiver.Obj().Name(), si.MethodName)
				req.addApplyFixAction(msg, fixMissingCalledFunction, req.loc)
			}

		// "undeclared name: X" or "undefined: X" compiler error.
		// Offer a "Create variable/function X" code action.
		// See [createUndeclared] for command implementation.
		case strings.HasPrefix(msg, "undeclared name: "),
			strings.HasPrefix(msg, "undefined: "):
			cur, _ := req.pgf.Cursor().FindByPos(start, end)
			title := undeclaredFixTitle(cur, msg)
			if title != "" {
				req.addApplyFixAction(title, fixCreateUndeclared, req.loc)
			}
		}
	}

	return nil
}

// allImportsFixesResult is the result of a lazy call to allImportsFixes.
// It implements the codeActionsRequest lazyInit interface.
type allImportsFixesResult struct {
	allFixEdits []protocol.TextEdit
	editsPerFix []*importFix
	err         error
}

func (res *allImportsFixesResult) init(ctx context.Context, req *codeActionsRequest) {
	res.allFixEdits, res.editsPerFix, res.err = allImportsFixes(ctx, req.snapshot, req.pgf)
	if res.err != nil {
		event.Error(ctx, "imports fixes", res.err, label.File.Of(req.loc.URI.Path()))
	}
}

func importFixTitle(fix *imports.ImportFix) string {
	var str string
	switch fix.FixType {
	case imports.AddImport:
		str = fmt.Sprintf("Add import: %s %q", fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
	case imports.DeleteImport:
		str = fmt.Sprintf("Delete import: %s %q", fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
	case imports.SetImportName:
		str = fmt.Sprintf("Rename import: %s %q", fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
	}
	return str
}

// fixedByImportFix filters the provided slice of diagnostics to those that
// would be fixed by the provided imports fix.
func fixedByImportFix(fix *imports.ImportFix, diagnostics []protocol.Diagnostic) []protocol.Diagnostic {
	var results []protocol.Diagnostic
	for _, diagnostic := range diagnostics {
		switch {
		// "undeclared name: X" may be an unresolved import.
		case strings.HasPrefix(diagnostic.Message, "undeclared name: "):
			ident := strings.TrimPrefix(diagnostic.Message, "undeclared name: ")
			if ident == fix.IdentName {
				results = append(results, diagnostic)
			}
		// "undefined: X" may be an unresolved import at Go 1.20+.
		case strings.HasPrefix(diagnostic.Message, "undefined: "):
			ident := strings.TrimPrefix(diagnostic.Message, "undefined: ")
			if ident == fix.IdentName {
				results = append(results, diagnostic)
			}
		// "could not import: X" may be an invalid import.
		case strings.HasPrefix(diagnostic.Message, "could not import: "):
			ident := strings.TrimPrefix(diagnostic.Message, "could not import: ")
			if ident == fix.IdentName {
				results = append(results, diagnostic)
			}
		// "X imported but not used" is an unused import.
		// "X imported but not used as Y" is an unused import.
		case strings.Contains(diagnostic.Message, " imported but not used"):
			idx := strings.Index(diagnostic.Message, " imported but not used")
			importPath := diagnostic.Message[:idx]
			if importPath == fmt.Sprintf("%q", fix.StmtInfo.ImportPath) {
				results = append(results, diagnostic)
			}
		}
	}
	return results
}

// goFreeSymbols produces "Browse free symbols" code actions.
// See [server.commandHandler.FreeSymbols] for command implementation.
func goFreeSymbols(ctx context.Context, req *codeActionsRequest) error {
	if !req.loc.Empty() {
		cmd := command.NewFreeSymbolsCommand("Browse free symbols", req.snapshot.View().ID(), req.loc)
		req.addCommandAction(cmd, false)
	}
	return nil
}

// goSplitPackage produces "Split package p" code actions.
// See [server.commandHandler.SplitPackage] for command implementation.
func goSplitPackage(ctx context.Context, req *codeActionsRequest) error {
	// TODO(adonovan): ideally we would key by the package path,
	// or the ID of the widest package for the current file,
	// so that we don't see different results when toggling
	// between p.go and p_test.go.
	//
	// TODO(adonovan): opt: req should always provide metadata so
	// that we don't have to request type checking (needPkg=true).
	meta := req.pkg.Metadata()
	title := fmt.Sprintf("Split package %q", meta.Name)
	cmd := command.NewSplitPackageCommand(title, req.snapshot.View().ID(), string(meta.ID))
	req.addCommandAction(cmd, false)
	return nil
}

// goplsDocFeatures produces "Browse gopls feature documentation" code actions.
// See [server.commandHandler.ClientOpenURL] for command implementation.
func goplsDocFeatures(ctx context.Context, req *codeActionsRequest) error {
	cmd := command.NewClientOpenURLCommand(
		"Browse gopls feature documentation",
		"https://go.dev/gopls/features")
	req.addCommandAction(cmd, false)
	return nil
}

// goDoc produces "Browse documentation for X" code actions.
// See [server.commandHandler.Doc] for command implementation.
func goDoc(ctx context.Context, req *codeActionsRequest) error {
	_, _, title := DocFragment(req.pkg, req.pgf, req.start, req.end)
	if title != "" {
		cmd := command.NewDocCommand(title, command.DocArgs{Location: req.loc, ShowDocument: true})
		req.addCommandAction(cmd, false)
	}
	return nil
}

// refactorExtractFunction produces "Extract function" code actions.
// See [extractFunction] for command implementation.
func refactorExtractFunction(ctx context.Context, req *codeActionsRequest) error {
	if _, ok, _, _ := canExtractFunction(req.pgf.Cursor(), req.start, req.end); ok {
		req.addApplyFixAction("Extract function", fixExtractFunction, req.loc)
	}
	return nil
}

// refactorExtractMethod produces "Extract method" code actions.
// See [extractMethod] for command implementation.
func refactorExtractMethod(ctx context.Context, req *codeActionsRequest) error {
	if _, ok, methodOK, _ := canExtractFunction(req.pgf.Cursor(), req.start, req.end); ok && methodOK {
		req.addApplyFixAction("Extract method", fixExtractMethod, req.loc)
	}
	return nil
}

// refactorExtractVariable produces "Extract variable|constant" code actions.
// See [extractVariable] for command implementation.
func refactorExtractVariable(ctx context.Context, req *codeActionsRequest) error {
	info := req.pkg.TypesInfo()
	if curExprs, err := canExtractVariable(info, req.pgf.Cursor(), req.start, req.end, false); err == nil && len(curExprs) > 0 {
		// Offer one of refactor.extract.{constant,variable}
		// based on the constness of the expression; this is a
		// limitation of the codeActionProducers mechanism.
		// Beware that future evolutions of the refactorings
		// may make them diverge to become non-complementary,
		// for example because "if const x = ...; y {" is illegal.
		// Same as [refactorExtractVariableAll].
		expr0 := curExprs[0].Node().(ast.Expr)
		constant := info.Types[expr0].Value != nil
		if (req.kind == settings.RefactorExtractConstant) == constant {
			title := "Extract variable"
			if constant {
				title = "Extract constant"
			}
			req.addApplyFixAction(title, fixExtractVariable, req.loc)
		}
	}
	return nil
}

// refactorExtractVariableAll produces "Extract N occurrences of EXPR" code action.
// See [extractVariable] for implementation.
func refactorExtractVariableAll(ctx context.Context, req *codeActionsRequest) error {
	info := req.pkg.TypesInfo()
	// Don't suggest if only one expr is found,
	// otherwise it will duplicate with [refactorExtractVariable]
	if curExprs, err := canExtractVariable(info, req.pgf.Cursor(), req.start, req.end, true); err == nil && len(curExprs) > 1 {
		expr0 := curExprs[0].Node().(ast.Expr)
		text, err := req.pgf.NodeText(expr0)
		if err != nil {
			return err
		}
		desc := string(text)
		if len(desc) >= 40 || strings.Contains(desc, "\n") {
			desc = goastutil.NodeDescription(expr0)
		}
		constant := info.Types[expr0].Value != nil
		if (req.kind == settings.RefactorExtractConstantAll) == constant {
			var title string
			if constant {
				title = fmt.Sprintf("Extract %d occurrences of const expression: %s", len(curExprs), desc)
			} else {
				title = fmt.Sprintf("Extract %d occurrences of %s", len(curExprs), desc)
			}
			req.addApplyFixAction(title, fixExtractVariableAll, req.loc)
		}
	}
	return nil
}

// refactorExtractToNewFile produces "Extract declarations to new file" code actions.
// See [server.commandHandler.ExtractToNewFile] for command implementation.
func refactorExtractToNewFile(ctx context.Context, req *codeActionsRequest) error {
	if canExtractToNewFile(req.pgf, req.start, req.end) {
		cmd := command.NewExtractToNewFileCommand("Extract declarations to new file", req.loc)
		req.addCommandAction(cmd, false)
	}
	return nil
}

// addTest produces "Add test for FUNC" code actions.
// See [server.commandHandler.AddTest] for command implementation.
func addTest(ctx context.Context, req *codeActionsRequest) error {
	// Reject test package.
	if req.pkg.Metadata().ForTest != "" {
		return nil
	}

	path, _ := goastutil.PathEnclosingInterval(req.pgf.File, req.start, req.end)
	if len(path) < 2 {
		return nil
	}

	decl, ok := path[len(path)-2].(*ast.FuncDecl)
	if !ok {
		return nil
	}

	// Don't offer to create tests of "init" or "_".
	if decl.Name.Name == "_" || decl.Name.Name == "init" {
		return nil
	}

	// TODO(hxjiang): support functions with type parameter.
	if decl.Type.TypeParams != nil {
		return nil
	}

	cmd := command.NewAddTestCommand("Add test for "+decl.Name.String(), req.loc)
	req.addCommandAction(cmd, false)

	// TODO(hxjiang): add code action for generate test for package/file.
	return nil
}

// identityTransform returns a change signature transformation that leaves the
// given fieldlist unmodified.
func identityTransform(fields *ast.FieldList) []command.ChangeSignatureParam {
	var id []command.ChangeSignatureParam
	for i := 0; i < fields.NumFields(); i++ {
		id = append(id, command.ChangeSignatureParam{OldIndex: i})
	}
	return id
}

// refactorRewriteRemoveUnusedParam produces "Remove unused parameter" code actions.
// See [server.commandHandler.ChangeSignature] for command implementation.
func refactorRewriteRemoveUnusedParam(ctx context.Context, req *codeActionsRequest) error {
	if info := removableParameter(req.pkg, req.pgf, req.loc.Range); info != nil {
		var transform []command.ChangeSignatureParam
		for i := 0; i < info.decl.Type.Params.NumFields(); i++ {
			if i != info.paramIndex {
				transform = append(transform, command.ChangeSignatureParam{OldIndex: i})
			}
		}
		cmd := command.NewChangeSignatureCommand("Remove unused parameter", command.ChangeSignatureArgs{
			Location:     req.loc,
			NewParams:    transform,
			NewResults:   identityTransform(info.decl.Type.Results),
			ResolveEdits: req.resolveEdits(),
		})
		req.addCommandAction(cmd, true)
	}
	return nil
}

func refactorRewriteMoveParamLeft(ctx context.Context, req *codeActionsRequest) error {
	if info := findParam(req.pgf, req.loc.Range); info != nil &&
		info.paramIndex > 0 &&
		!is[*ast.Ellipsis](info.field.Type) {

		// ^^ we can't currently handle moving a variadic param.
		// TODO(rfindley): implement.

		transform := identityTransform(info.decl.Type.Params)
		transform[info.paramIndex] = command.ChangeSignatureParam{OldIndex: info.paramIndex - 1}
		transform[info.paramIndex-1] = command.ChangeSignatureParam{OldIndex: info.paramIndex}
		cmd := command.NewChangeSignatureCommand("Move parameter left", command.ChangeSignatureArgs{
			Location:     req.loc,
			NewParams:    transform,
			NewResults:   identityTransform(info.decl.Type.Results),
			ResolveEdits: req.resolveEdits(),
		})

		req.addCommandAction(cmd, true)
	}
	return nil
}

func refactorRewriteMoveParamRight(ctx context.Context, req *codeActionsRequest) error {
	if info := findParam(req.pgf, req.loc.Range); info != nil && info.paramIndex >= 0 {
		params := info.decl.Type.Params
		nparams := params.NumFields()
		if info.paramIndex < nparams-1 { // not the last param
			if info.paramIndex == nparams-2 && is[*ast.Ellipsis](params.List[len(params.List)-1].Type) {
				// We can't currently handle moving a variadic param.
				// TODO(rfindley): implement.
				return nil
			}

			transform := identityTransform(info.decl.Type.Params)
			transform[info.paramIndex] = command.ChangeSignatureParam{OldIndex: info.paramIndex + 1}
			transform[info.paramIndex+1] = command.ChangeSignatureParam{OldIndex: info.paramIndex}
			cmd := command.NewChangeSignatureCommand("Move parameter right", command.ChangeSignatureArgs{
				Location:     req.loc,
				NewParams:    transform,
				NewResults:   identityTransform(info.decl.Type.Results),
				ResolveEdits: req.resolveEdits(),
			})
			req.addCommandAction(cmd, true)
		}
	}
	return nil
}

// refactorRewriteChangeQuote produces "Convert to {raw,interpreted} string literal" code actions.
func refactorRewriteChangeQuote(ctx context.Context, req *codeActionsRequest) error {
	convertStringLiteral(req)
	return nil
}

// refactorRewriteInvertIf produces "Invert 'if' condition" code actions.
// See [invertIfCondition] for command implementation.
func refactorRewriteInvertIf(ctx context.Context, req *codeActionsRequest) error {
	if _, ok, _ := canInvertIfCondition(req.pgf.Cursor(), req.start, req.end); ok {
		req.addApplyFixAction("Invert 'if' condition", fixInvertIfCondition, req.loc)
	}
	return nil
}

// refactorRewriteSplitLines produces "Split ITEMS into separate lines" code actions.
// See [splitLines] for command implementation.
func refactorRewriteSplitLines(ctx context.Context, req *codeActionsRequest) error {
	// TODO(adonovan): opt: don't set needPkg just for FileSet.
	if msg, ok, _ := canSplitLines(req.pgf.Cursor(), req.pkg.FileSet(), req.start, req.end); ok {
		req.addApplyFixAction(msg, fixSplitLines, req.loc)
	}
	return nil
}

func refactorRewriteEliminateDotImport(ctx context.Context, req *codeActionsRequest) error {
	// Figure out if the request is placed over a dot import.
	var importSpec *ast.ImportSpec
	for _, imp := range req.pgf.File.Imports {
		if posRangeContains(imp.Pos(), imp.End(), req.start, req.end) {
			importSpec = imp
			break
		}
	}
	if importSpec == nil {
		return nil
	}
	if importSpec.Name == nil || importSpec.Name.Name != "." {
		return nil
	}

	// dotImported package path and its imported name after removing the dot.
	pkgname := req.pkg.TypesInfo().PkgNameOf(importSpec)
	if pkgname == nil {
		return nil // e.g. import . "C"
	}
	imported := pkgname.Imported()
	newName := imported.Name()

	rng, err := req.pgf.PosRange(importSpec.Name.Pos(), importSpec.Path.Pos())
	if err != nil {
		return err
	}
	// Delete the '.' part of the import.
	edits := []protocol.TextEdit{{
		Range: rng,
	}}

	fileScope, ok := req.pkg.TypesInfo().Scopes[req.pgf.File]
	if !ok {
		return nil
	}

	// Go through each use of the dot imported package, checking its scope for
	// shadowing and calculating an edit to qualify the identifier.
	for curId := range req.pgf.Cursor().Preorder((*ast.Ident)(nil)) {
		ident := curId.Node().(*ast.Ident)

		// Only keep identifiers that use a symbol from the
		// dot imported package.
		use := req.pkg.TypesInfo().Uses[ident]
		if use == nil || use.Pkg() == nil {
			continue
		}
		if use.Pkg() != imported {
			continue
		}

		// Only qualify unqualified identifiers (due to dot imports)
		// that reference package-level symbols.
		// All other references to a symbol imported from another package
		// are nested within a select expression (pkg.Foo, v.Method, v.Field).
		if curId.ParentEdgeKind() == edge.SelectorExpr_Sel {
			continue // qualified identifier (pkg.X) or selector (T.X or e.X)
		}
		if !typesinternal.IsPackageLevel(use) {
			continue // unqualified field reference T{X: ...}
		}

		// Make sure that the package name will not be shadowed by something else in scope.
		// If it is then we cannot offer this particular code action.
		//
		// TODO: If the object found in scope is the package imported without a
		// dot, or some builtin not used in the file, the code action could be
		// allowed to go through.
		sc := fileScope.Innermost(ident.Pos())
		if sc == nil {
			continue
		}
		_, obj := sc.LookupParent(newName, ident.Pos())
		if obj != nil {
			continue
		}

		rng, err := req.pgf.PosRange(ident.Pos(), ident.Pos()) // sic, zero-width range before ident
		if err != nil {
			continue
		}
		edits = append(edits, protocol.TextEdit{
			Range:   rng,
			NewText: newName + ".",
		})
	}

	req.addEditAction("Eliminate dot import", nil, protocol.DocumentChangeEdit(
		req.fh,
		edits,
	))
	return nil
}

// refactorRewriteJoinLines produces "Join ITEMS into one line" code actions.
// See [joinLines] for command implementation.
func refactorRewriteJoinLines(ctx context.Context, req *codeActionsRequest) error {
	// TODO(adonovan): opt: don't set needPkg just for FileSet.
	if msg, ok, _ := canJoinLines(req.pgf.Cursor(), req.pkg.FileSet(), req.start, req.end); ok {
		req.addApplyFixAction(msg, fixJoinLines, req.loc)
	}
	return nil
}

// refactorRewriteFillStruct produces "Fill STRUCT" code actions.
// See [fillstruct.SuggestedFix] for command implementation.
func refactorRewriteFillStruct(ctx context.Context, req *codeActionsRequest) error {
	// fillstruct.Diagnose is a lazy analyzer: all it gives us is
	// the (start, end, message) of each SuggestedFix; the actual
	// edit is computed only later by ApplyFix, which calls fillstruct.SuggestedFix.
	for _, diag := range fillstruct.Diagnose(req.pgf.File, req.start, req.end, req.pkg.Types(), req.pkg.TypesInfo()) {
		loc, err := req.pgf.Mapper.PosLocation(req.pgf.Tok, diag.Pos, diag.End)
		if err != nil {
			return err
		}
		for _, fix := range diag.SuggestedFixes {
			req.addApplyFixAction(fix.Message, diag.Category, loc)
		}
	}
	return nil
}

// refactorRewriteFillSwitch produces "Add cases for TYPE/ENUM" code actions.
func refactorRewriteFillSwitch(ctx context.Context, req *codeActionsRequest) error {
	for _, diag := range fillswitch.Diagnose(req.pgf.File, req.start, req.end, req.pkg.Types(), req.pkg.TypesInfo()) {
		changes, err := suggestedFixToDocumentChange(ctx, req.snapshot, req.pkg.FileSet(), &diag.SuggestedFixes[0])
		if err != nil {
			return err
		}
		req.addEditAction(diag.Message, nil, changes...)
	}

	return nil
}

// selectionContainsStructField returns true if the given struct contains a
// field between start and end pos. If needsTag is true, it only returns true if
// the struct field found contains a struct tag.
func selectionContainsStructField(node *ast.StructType, start, end token.Pos, needsTag bool) bool {
	for _, field := range node.Fields.List {
		if start <= field.End() && end >= field.Pos() {
			if !needsTag || field.Tag != nil {
				return true
			}
		}
	}
	return false
}

// selectionContainsStruct returns true if there exists a struct containing
// fields within start and end positions. If removeTags is true, it means the
// current command is for remove tags rather than add tags, so we only return
// true if the struct field found contains a struct tag to remove.
func selectionContainsStruct(cursor inspector.Cursor, start, end token.Pos, removeTags bool) bool {
	cur, ok := cursor.FindByPos(start, end)
	if !ok {
		return false
	}
	if _, ok := cur.Node().(*ast.StructType); ok {
		return true
	}

	// Handles case where selection is within struct.
	for c := range cur.Enclosing((*ast.StructType)(nil)) {
		if selectionContainsStructField(c.Node().(*ast.StructType), start, end, removeTags) {
			return true
		}
	}

	// Handles case where selection contains struct but may contain other nodes, including other structs.
	for c := range cur.Preorder((*ast.StructType)(nil)) {
		node := c.Node().(*ast.StructType)
		// Check that at least one field is located within the selection. If we are removing tags, that field
		// must also have a struct tag, otherwise we do not provide the code action.
		if selectionContainsStructField(node, start, end, removeTags) {
			return true
		}
	}
	return false
}

// supportsDialog reports whether the client supports interactive UI dialogs.
// If specific [settings.InteractiveInputType]s are provided, it also verifies that
// the client explicitly supports every requested input type.
func supportsDialog(req *codeActionsRequest, need ...settings.InteractiveInputType) bool {
	// TODO(pjw): this would be better if it checked the actual form, e.g., server.AddTagsForm
	// rather than the types, but that would cause an imports loop.
	o := req.options.ClientOptions.SupportedInteractiveInputTypes
	if o == nil {
		return false
	}
	for _, n := range need {
		if !o[n] {
			return false
		}
	}
	return true
}

// refactorRewriteAddStructTags produces "Add struct tags" code actions.
// See [server.commandHandler.ModifyTags] for command implementation.
func refactorRewriteAddStructTags(ctx context.Context, req *codeActionsRequest) error {
	if selectionContainsStruct(req.pgf.Cursor(), req.start, req.end, false) {
		add := ""
		if !supportsDialog(req) {
			add = "json" // default choice
		}
		cmdAdd := command.NewModifyTagsCommand("Add struct tags", command.ModifyTagsArgs{
			Modification: "add",
			URI:          req.loc.URI,
			Range:        req.loc.Range,
			Add:          add,
		})
		req.addCommandAction(cmdAdd, false)
	}
	return nil
}

// refactorRewriteRemoveStructTags produces "Remove struct tags" code actions.
// See [server.commandHandler.ModifyTags] for command implementation.
func refactorRewriteRemoveStructTags(ctx context.Context, req *codeActionsRequest) error {
	if selectionContainsStruct(req.pgf.Cursor(), req.start, req.end, true) {
		clear := !supportsDialog(req) // clear the entry if there is no dialog
		cmdRemove := command.NewModifyTagsCommand("Remove struct tags", command.ModifyTagsArgs{
			Modification: "remove",
			URI:          req.loc.URI,
			Range:        req.loc.Range,
			Clear:        clear,
		})
		req.addCommandAction(cmdRemove, false)
	}
	return nil
}

// removableParameter returns paramInfo about a removable parameter indicated
// by the given [start, end) range, or nil if no such removal is available.
//
// Removing a parameter is possible if
//   - there are no parse or type errors, and
//   - [start, end) is contained within an unused field or parameter name
//   - ... of a non-method function declaration.
//
// (Note that the unusedparam analyzer also computes this property, but
// much more precisely, allowing it to report its findings as diagnostics.)
//
// TODO(adonovan): inline into refactorRewriteRemoveUnusedParam.
func removableParameter(pkg *cache.Package, pgf *parsego.File, rng protocol.Range) *paramInfo {
	if perrors, terrors := pkg.ParseErrors(), pkg.TypeErrors(); len(perrors) > 0 || len(terrors) > 0 {
		return nil // can't remove parameters from packages with errors
	}
	info := findParam(pgf, rng)
	if info == nil || info.field == nil {
		return nil // range does not span a parameter
	}
	if info.decl.Body == nil {
		return nil // external function
	}
	if len(info.field.Names) == 0 {
		return info // no names => field is unused
	}
	if info.name == nil {
		return nil // no name is indicated
	}
	if info.name.Name == "_" {
		return info // trivially unused
	}

	obj := pkg.TypesInfo().Defs[info.name]
	if obj == nil {
		return nil // something went wrong
	}

	used := false
	ast.Inspect(info.decl.Body, func(node ast.Node) bool {
		if n, ok := node.(*ast.Ident); ok && pkg.TypesInfo().Uses[n] == obj {
			used = true
		}
		return !used // keep going until we find a use
	})
	if used {
		return nil
	}
	return info
}

// refactorInlineCall produces "Inline call to FUNC" code actions.
// See [inlineCall] for command implementation.
func refactorInlineCall(ctx context.Context, req *codeActionsRequest) error {
	// To avoid distraction (e.g. VS Code lightbulb), offer "inline"
	// only after a selection or explicit menu operation.
	// TODO(adonovan): remove this (and req.trigger); see comment at TestVSCodeIssue65167.
	if req.trigger == protocol.CodeActionAutomatic && req.loc.Empty() {
		return nil
	}

	// If range is within call expression, offer to inline the call.
	if _, fn, err := enclosingStaticCall(req.pkg, req.pgf, req.start, req.end); err == nil {
		req.addApplyFixAction("Inline call to "+fn.Name(), fixInlineCall, req.loc)
	}
	return nil
}

// refactorInlineVariable produces the "Inline variable 'v'" code action.
// See [inlineVariableOne] for command implementation.
func refactorInlineVariable(ctx context.Context, req *codeActionsRequest) error {
	// TODO(adonovan): offer "inline all" variant that eliminates the var (see #70085).
	if curUse, _, ok := canInlineVariable(req.pkg.TypesInfo(), req.pgf.Cursor(), req.start, req.end); ok {
		title := fmt.Sprintf("Inline variable %q", curUse.Node().(*ast.Ident).Name)
		req.addApplyFixAction(title, fixInlineVariable, req.loc)
	}
	return nil
}

// goTest produces "Run tests and benchmarks" code actions.
// See [server.commandHandler.runTests] for command implementation.
func goTest(ctx context.Context, req *codeActionsRequest) error {
	testFuncs, benchFuncs, err := testsAndBenchmarks(req.pkg.TypesInfo(), req.pgf)
	if err != nil {
		return err
	}

	var tests, benchmarks []string
	for _, fn := range testFuncs {
		if protocol.Intersect(fn.rng, req.loc.Range) {
			tests = append(tests, fn.name)
		}
	}
	for _, fn := range benchFuncs {
		if protocol.Intersect(fn.rng, req.loc.Range) {
			benchmarks = append(benchmarks, fn.name)
		}
	}

	if len(tests) == 0 && len(benchmarks) == 0 {
		return nil
	}

	cmd := command.NewRunTestsCommand("Run tests and benchmarks", command.RunTestsArgs{
		URI:        req.loc.URI,
		Tests:      tests,
		Benchmarks: benchmarks,
	})
	req.addCommandAction(cmd, false)
	return nil
}

// goAssembly produces "Browse ARCH assembly for FUNC" code actions.
// See [server.commandHandler.Assembly] for command implementation.
func goAssembly(ctx context.Context, req *codeActionsRequest) error {
	view := req.snapshot.View()

	// Find the enclosing toplevel function or method,
	// and compute its symbol name (e.g. "pkgpath.(T).method").
	// The report will show this method and all its nested
	// functions (FuncLit, defers, etc).
	//
	// TODO(adonovan): this is no good for generics, since they
	// will always be uninstantiated when they enclose the cursor.
	// Instead, we need to query the func symbol under the cursor,
	// rather than the enclosing function. It may be an explicitly
	// or implicitly instantiated generic, and it may be defined
	// in another package, though we would still need to compile
	// the current package to see its assembly. The challenge,
	// however, is that computing the linker name for a generic
	// symbol is quite tricky. Talk with the compiler team for
	// ideas.
	//
	// TODO(adonovan): think about a smoother UX for jumping
	// directly to (say) a lambda of interest.
	// Perhaps we could scroll to STEXT for the innermost
	// enclosing nested function?

	// Compute the linker symbol of the enclosing function or var initializer.
	var sym strings.Builder
	if pkg := req.pkg.Types(); pkg.Name() == "main" {
		sym.WriteString("main")
	} else {
		sym.WriteString(pkg.Path())
	}
	sym.WriteString(".")

	curSel, _ := req.pgf.Cursor().FindByPos(req.start, req.end)
	for cur := range curSel.Enclosing((*ast.FuncDecl)(nil), (*ast.ValueSpec)(nil)) {
		var name string // in command title
		switch node := cur.Node().(type) {
		case *ast.FuncDecl:
			// package-level func or method
			if fn, ok := req.pkg.TypesInfo().Defs[node.Name].(*types.Func); ok &&
				fn.Name() != "_" { // blank functions are not compiled

				// Source-level init functions are compiled (along with
				// package-level var initializers) in into a single pkg.init
				// function, so this falls out of the logic below.

				if sig := fn.Signature(); sig.TypeParams() == nil && sig.RecvTypeParams() == nil { // generic => no assembly
					if sig.Recv() != nil {
						if isPtr, named := typesinternal.ReceiverNamed(sig.Recv()); named != nil {
							if isPtr {
								fmt.Fprintf(&sym, "(*%s)", named.Obj().Name())
							} else {
								sym.WriteString(named.Obj().Name())
							}
							sym.WriteByte('.')
						}
					}
					sym.WriteString(fn.Name())

					name = node.Name.Name // success
				}
			}

		case *ast.ValueSpec:
			// package-level var initializer?
			if len(node.Names) > 0 && len(node.Values) > 0 {
				v := req.pkg.TypesInfo().Defs[node.Names[0]]
				if v != nil && typesinternal.IsPackageLevel(v) {
					sym.WriteString("init")
					name = "package initializer" // success
				}
			}
		}

		if name != "" {
			cmd := command.NewAssemblyCommand(
				fmt.Sprintf("Browse %s assembly for %s", view.GOARCH(), name),
				view.ID(),
				string(req.pkg.Metadata().ID),
				sym.String())
			req.addCommandAction(cmd, false)
			break
		}
	}
	return nil
}

// toggleCompilerOptDetails produces "{Show,Hide} compiler optimization details" code action.
// See [server.commandHandler.GCDetails] for command implementation.
func toggleCompilerOptDetails(ctx context.Context, req *codeActionsRequest) error {
	// TODO(adonovan): errors from code action providers should probably be
	// logged, even if they aren't visible to the client; see https://go.dev/issue/71275.
	if meta, err := req.snapshot.NarrowestMetadataForFile(ctx, req.fh.URI()); err == nil {
		if len(meta.CompiledGoFiles) == 0 {
			return fmt.Errorf("package %q does not compile file %q", meta.ID, req.fh.URI())
		}
		dir := meta.CompiledGoFiles[0].Dir()

		title := fmt.Sprintf("%s compiler optimization details for %q",
			cond(req.snapshot.WantCompilerOptDetails(dir), "Hide", "Show"),
			dir.Base())
		cmd := command.NewGCDetailsCommand(title, req.fh.URI())
		req.addCommandAction(cmd, false)
	}
	return nil
}

// (this function is unused)
func refactorMoveType(_ context.Context, req *codeActionsRequest) error {
	curSel, _ := req.pgf.Cursor().FindByPos(req.start, req.end)
	if _, _, _, typeName, ok := selectionContainsType(curSel); ok {
		cmd := command.NewMoveTypeCommand(fmt.Sprintf("Move type %s", typeName), command.MoveTypeArgs{Location: req.loc})
		req.addCommandAction(cmd, false)
	}
	return nil
}


================================================
FILE: gopls/internal/golang/comment.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/doc/comment"
	"go/token"
	"go/types"
	"iter"
	pathpkg "path"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/astutil"
)

var errNoCommentReference = errors.New("no comment reference found")

// DocCommentToMarkdown converts the text of a [doc comment] to Markdown.
//
// TODO(adonovan): provide a package (or file imports) as context for
// proper rendering of doc links; see [newDocCommentParser] and golang/go#61677.
//
// [doc comment]: https://go.dev/doc/comment
func DocCommentToMarkdown(text string, options *settings.Options) string {
	var parser comment.Parser
	doc := parser.Parse(text)

	var printer comment.Printer
	// The default produces {#Hdr-...} tags for headings.
	// vscode displays thems, which is undesirable.
	// The godoc for comment.Printer says the tags
	// avoid a security problem.
	printer.HeadingID = func(*comment.Heading) string { return "" }
	printer.DocLinkURL = func(link *comment.DocLink) string {
		msg := fmt.Sprintf("https://%s/%s", options.LinkTarget, link.ImportPath)
		if link.Name != "" {
			msg += "#"
			if link.Recv != "" {
				msg += link.Recv + "."
			}
			msg += link.Name
		}
		return msg
	}

	return string(printer.Markdown(doc))
}

// docLinkDefinition finds the definition of the doc link in comments at pos.
// If there is no reference at pos, returns errNoCommentReference.
//
// TODO(hxjiang): simplify the error handling.
func docLinkDefinition(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) ([]protocol.Location, error) {
	obj, _, err := resolveDocLink(pkg, pgf, astutil.RangeOf(start, end))
	if err != nil {
		return nil, err
	}
	loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, obj)
	if err != nil {
		return nil, err
	}
	return []protocol.Location{loc}, nil
}

// resolveDocLink parses a doc link in a comment such as [fmt.Println]
// and returns the symbol at pos, along with the link's range.
func resolveDocLink(pkg *cache.Package, pgf *parsego.File, rng astutil.Range) (types.Object, protocol.Range, error) {
	var comment *ast.CommentGroup
	for _, c := range pgf.File.Comments {
		if astutil.NodeContains(c, rng) {
			comment = c
			break
		}
	}

	if comment == nil {
		return nil, protocol.Range{}, errNoCommentReference
	}

	for docLink := range commentDocLinks(comment) {
		if astutil.NodeContains(docLink.partRange, rng) {
			if obj := lookupDocLinkSymbol(pkg, pgf, docLink.nameText); obj != nil {
				rng, err := pgf.NodeRange(docLink.partRange)
				if err != nil {
					return nil, protocol.Range{}, err
				}
				return obj, rng, nil
			}
			break
		}
	}

	return nil, protocol.Range{}, errNoCommentReference
}

// A docLink holds the parsed information for a single resolution step of a
// documentation link. For a link like "[fmt.Scanner.Scan]", the parser will
// yield three docLink values, one for each progressively resolved part:
// "fmt", "fmt.Scanner", and "fmt.Scanner.Scan".
type docLink struct {
	// The text of the right-most component of the name for this step.
	// For the name "fmt.Scanner", this is "Scanner".
	partText  string
	partRange astutil.Range

	// The text of the fully-qualified symbol path resolved in this step.
	// For example, "fmt.Scanner". Used for symbol lookups.
	nameText string

	// The text of the entire, original doc link expression, including brackets.
	// For example, "[fmt.Scanner.Scan]".
	bracketText string
}

// commentDocLinks returns the sequence of Go doc links in the comment group.
// TODO(hxjiang): move to [parsego] package.
func commentDocLinks(cg *ast.CommentGroup) iter.Seq[docLink] {
	return func(yield func(docLink) bool) {
		for _, comment := range cg.List {
			// The canonical parsing algorithm is defined by go/doc/comment, but
			// unfortunately its API provides no way to reliably reconstruct the
			// position of each doc link from the parsed result.

			for _, idx := range docLinkRegex.FindAllStringSubmatchIndex(comment.Text, -1) {
				// [mstart, mend) identifies the first submatch, which is the
				// reference name in the doc link (sans '*').
				// e.g. The "[fmt.Println]" reference name is "fmt.Println".
				mstart, mend := idx[2], idx[3]

				// idx[0], idx[1] matches the full pattern. idx[0] corresponds
				// to the opening bracket. idx[1] may include trailing
				// whitespace or punctuation, so we need to use "mend" to
				// capture the exact location of the closing bracket, which must
				// be one space after the end of the reference name.
				bracketText := comment.Text[idx[0] : mend+1]

				match := comment.Text[mstart:mend]

				if strings.Contains(match, "\n") {
					continue
				}

				// [namePos.Start, namePos.End) identifies the start and end
				// position of a name. e.g. "fmt", "fmt.Scanner", "fmt.Scanner.Scan".
				var name string

				namePos := astutil.RangeOf(comment.Pos()+token.Pos(mstart), comment.Pos()+token.Pos(mstart-1))
				// [partPos.Start, partPos.End) identifies the start and end
				// position of a part. e.g. "fmt", "Scanner", "Scan".
				partPos := namePos
				for part := range strings.SplitSeq(match, ".") {
					if name != "" {
						name += "."
					}
					name += part

					partPos.Start = partPos.EndPos + token.Pos(len("."))  // Move start to the first char of next part
					partPos.EndPos = partPos.Start + token.Pos(len(part)) // Move end to next char of current part

					namePos.EndPos = partPos.EndPos

					if !yield(docLink{
						partRange:   partPos,
						partText:    part,
						nameText:    name,
						bracketText: bracketText,
					}) {
						return
					}
				}
			}
		}
	}
}

// lookupDocLinkSymbol returns the symbol denoted by a doc link such
// as "fmt.Println" or "bytes.Buffer.Write" in the specified file.
func lookupDocLinkSymbol(pkg *cache.Package, pgf *parsego.File, name string) types.Object {
	scope := pkg.Types().Scope()

	prefix, suffix, _ := strings.Cut(name, ".")

	// Try treating the prefix as a package name,
	// allowing for non-renaming and renaming imports.
	fileScope := pkg.TypesInfo().Scopes[pgf.File]
	if fileScope == nil {
		// As we learned in golang/go#69616, any file may not be Scopes!
		//  - A non-compiled Go file (such as unsafe.go) won't be in Scopes.
		//  - A (technically) compiled go file with the wrong package name won't be
		//    in Scopes, as it will be skipped by go/types.
		return nil
	}
	pkgname, ok := fileScope.Lookup(prefix).(*types.PkgName) // ok => prefix is imported name
	if !ok {
		// Handle renaming import, e.g.
		// [path.Join] after import pathpkg "path".
		// (Should we look at all files of the package?)
		for _, imp := range pgf.File.Imports {
			pkgname2 := pkg.TypesInfo().PkgNameOf(imp)
			if pkgname2 != nil && pkgname2.Imported().Name() == prefix {
				pkgname = pkgname2
				break
			}
		}
	}
	if pkgname != nil {
		scope = pkgname.Imported().Scope()
		if suffix == "" {
			return pkgname // not really a valid doc link
		}
		name = suffix
	}

	// TODO(adonovan): try searching the forward closure for packages
	// that define the symbol but are not directly imported;
	// see https://github.com/golang/go/issues/61677

	// Field or sel?
	recv, sel, ok := strings.Cut(name, ".")
	if ok {
		obj := scope.Lookup(recv) // package scope
		if obj == nil {
			obj = types.Universe.Lookup(recv)
		}
		obj, ok := obj.(*types.TypeName)
		if !ok {
			return nil
		}
		m, _, _ := types.LookupFieldOrMethod(obj.Type(), true, obj.Pkg(), sel)
		return m
	}

	if obj := scope.Lookup(name); obj != nil {
		return obj // package-level symbol
	}
	return types.Universe.Lookup(name) // built-in symbol
}

// newDocCommentParser returns a function that parses [doc comments],
// with context for Doc Links supplied by the specified package.
//
// Imported symbols are rendered using the import mapping for the file
// that encloses fileNode.
//
// The resulting function is not concurrency safe.
//
// See issue #61677 for how this might be generalized to support
// correct contextual parsing of doc comments in Hover too.
//
// [doc comment]: https://go.dev/doc/comment
func newDocCommentParser(pkg *cache.Package) func(fileNode ast.Node, text string) *comment.Doc {
	var currentFilePos token.Pos // pos whose enclosing file's import mapping should be used
	parser := &comment.Parser{
		LookupPackage: func(name string) (importPath string, ok bool) {
			for _, f := range pkg.Syntax() {
				// Different files in the same package have
				// different import mappings. Use the provided
				// syntax node to find the correct file.
				if astutil.NodeContainsPos(f, currentFilePos) {
					// First try each actual imported package name.
					for _, imp := range f.Imports {
						pkgName := pkg.TypesInfo().PkgNameOf(imp)
						if pkgName != nil && pkgName.Name() == name {
							return pkgName.Imported().Path(), true
						}
					}

					// Then try each imported package's declared name,
					// as some packages are typically imported under a
					// non-default name (e.g. pathpkg "path") but
					// may be referred to in doc links using their
					// canonical name.
					for _, imp := range f.Imports {
						pkgName := pkg.TypesInfo().PkgNameOf(imp)
						if pkgName != nil && pkgName.Imported().Name() == name {
							return pkgName.Imported().Path(), true
						}
					}

					// Finally try matching the last segment of each import
					// path imported by any file in the package, as the
					// doc comment may appear in a different file from the
					// import.
					//
					// Ideally we would look up the DepsByPkgPath value
					// (a PackageID) in the metadata graph and use the
					// package's declared name instead of this heuristic,
					// but we don't have access to the graph here.
					for path := range pkg.Metadata().DepsByPkgPath {
						if pathpkg.Base(trimVersionSuffix(string(path))) == name {
							return string(path), true
						}
					}

					break
				}
			}
			return "", false
		},
		LookupSym: func(recv, name string) (ok bool) {
			// package-level decl?
			if recv == "" {
				return pkg.Types().Scope().Lookup(name) != nil
			}

			// method?
			tname, ok := pkg.Types().Scope().Lookup(recv).(*types.TypeName)
			if !ok {
				return false
			}
			m, _, _ := types.LookupFieldOrMethod(tname.Type(), true, pkg.Types(), name)
			return is[*types.Func](m)
		},
	}
	return func(fileNode ast.Node, text string) *comment.Doc {
		currentFilePos = fileNode.Pos()
		return parser.Parse(text)
	}
}


================================================
FILE: gopls/internal/golang/compileropt.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
)

// CompilerOptDetails invokes the Go compiler with the "-json=0,dir"
// flag on the packages and tests in the specified directory, parses
// its log of optimization decisions, and returns them as a set of
// diagnostics.
func CompilerOptDetails(ctx context.Context, snapshot *cache.Snapshot, pkgDir protocol.DocumentURI) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	outDir, err := os.MkdirTemp("", fmt.Sprintf("gopls-%d.details", os.Getpid()))
	if err != nil {
		return nil, err
	}
	defer func() {
		if err := os.RemoveAll(outDir); err != nil {
			event.Error(ctx, "cleaning details dir", err)
		}
	}()

	outDirURI := protocol.URIFromPath(outDir)
	// details doesn't handle Windows URIs in the form of "file:///C:/...",
	// so rewrite them to "file://C:/...". See golang/go#41614.
	if !strings.HasPrefix(outDir, "/") {
		outDirURI = protocol.DocumentURI(strings.Replace(string(outDirURI), "file:///", "file://", 1))
	}

	// We use "go test -c" not "go build" as it covers all three packages
	// (p, "p [p.test]", "p_test [p.test]") in the directory, if they exist.
	// (See also assembly.go.)
	inv, cleanupInvocation, err := snapshot.GoCommandInvocation(cache.NoNetwork, pkgDir.Path(), "test", []string{
		"-c",
		"-vet=off", // weirdly -c doesn't disable vet
		fmt.Sprintf("-gcflags=-json=0,%s", outDirURI), // JSON schema version 0
		fmt.Sprintf("-o=%s", os.DevNull),
		".",
	})
	if err != nil {
		return nil, err
	}
	defer cleanupInvocation()
	_, err = snapshot.View().GoCommandRunner().Run(ctx, *inv)
	if err != nil {
		return nil, err
	}
	files, err := findJSONFiles(outDir)
	if err != nil {
		return nil, err
	}
	reports := make(map[protocol.DocumentURI][]*cache.Diagnostic)
	var parseError error
	for _, fn := range files {
		uri, diagnostics, err := parseDetailsFile(fn, snapshot.Options())
		if err != nil {
			// expect errors for all the files, save 1
			parseError = err
		}
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil || fh == nil {
			continue
		}
		if pkgDir != fh.URI().Dir() {
			// Filter compiler diagnostics to the requested directory.
			// https://github.com/golang/go/issues/42198
			// sometimes the detail diagnostics generated for files
			// outside the package can never be taken back.
			continue
		}
		reports[fh.URI()] = diagnostics
	}
	return reports, parseError
}

// parseDetailsFile parses the file written by the Go compiler which contains a JSON-encoded protocol.Diagnostic.
func parseDetailsFile(filename string, options *settings.Options) (protocol.DocumentURI, []*cache.Diagnostic, error) {
	buf, err := os.ReadFile(filename)
	if err != nil {
		return "", nil, err
	}
	var (
		uri         protocol.DocumentURI
		i           int
		diagnostics []*cache.Diagnostic
	)
	type metadata struct {
		File string `json:"file,omitempty"`
	}
	for dec := json.NewDecoder(bytes.NewReader(buf)); dec.More(); {
		// The first element always contains metadata.
		if i == 0 {
			i++
			m := new(metadata)
			if err := dec.Decode(m); err != nil {
				return "", nil, err
			}
			if !strings.HasSuffix(m.File, ".go") {
				continue // <autogenerated>
			}
			uri = protocol.URIFromPath(m.File)
			continue
		}
		d := new(protocol.Diagnostic)
		if err := dec.Decode(d); err != nil {
			return "", nil, err
		}
		d.Tags = []protocol.DiagnosticTag{} // must be an actual slice
		msg := d.Code.(string)
		if msg != "" {
			msg = fmt.Sprintf("%s(%s)", msg, d.Message)
		}
		if !showDiagnostic(msg, d.Source, options) {
			continue
		}

		// zeroIndexedRange subtracts 1 from the line and
		// range, because the compiler output neglects to
		// convert from 1-based UTF-8 coordinates to 0-based UTF-16.
		// (See GOROOT/src/cmd/compile/internal/logopt/log_opts.go.)
		// TODO(rfindley): also translate UTF-8 to UTF-16.
		zeroIndexedRange := func(rng protocol.Range) protocol.Range {
			return protocol.Range{
				Start: protocol.Position{
					Line:      rng.Start.Line - 1,
					Character: rng.Start.Character - 1,
				},
				End: protocol.Position{
					Line:      rng.End.Line - 1,
					Character: rng.End.Character - 1,
				},
			}
		}

		var related []protocol.DiagnosticRelatedInformation
		for _, ri := range d.RelatedInformation {
			related = append(related, protocol.DiagnosticRelatedInformation{
				Location: ri.Location.URI.Location(zeroIndexedRange(ri.Location.Range)),
				Message:  ri.Message,
			})
		}
		diagnostic := &cache.Diagnostic{
			URI:      uri,
			Range:    zeroIndexedRange(d.Range),
			Message:  msg,
			Severity: d.Severity,
			Source:   cache.CompilerOptDetailsInfo, // d.Source is always "go compiler" as of 1.16, use our own
			Tags:     d.Tags,
			Related:  related,
		}
		diagnostics = append(diagnostics, diagnostic)
		i++
	}
	return uri, diagnostics, nil
}

// showDiagnostic reports whether a given diagnostic should be shown to the end
// user, given the current options.
func showDiagnostic(msg, source string, o *settings.Options) bool {
	if source != "go compiler" {
		return false
	}
	if o.Annotations == nil {
		return true
	}

	// The strings below were gathered by grepping the source of
	// cmd/compile for literal arguments in calls to logopt.LogOpt.
	// (It is not a well defined set.)
	//
	// - canInlineFunction
	// - cannotInlineCall
	// - cannotInlineFunction
	// - escape
	// - escapes
	// - isInBounds
	// - isSliceInBounds
	// - leak
	// - nilcheck
	//
	// Additional ones not handled by logic below:
	// - copy
	// - iteration-variable-to-{heap,stack}
	// - loop-modified-{range,for}

	switch {
	case strings.HasPrefix(msg, "canInline") ||
		strings.HasPrefix(msg, "cannotInline") ||
		strings.HasPrefix(msg, "inlineCall"):
		return o.Annotations[settings.Inline]
	case strings.HasPrefix(msg, "escape") || msg == "leak":
		return o.Annotations[settings.Escape]
	case strings.HasPrefix(msg, "nilcheck"):
		return o.Annotations[settings.Nil]
	case strings.HasPrefix(msg, "isInBounds") ||
		strings.HasPrefix(msg, "isSliceInBounds"):
		return o.Annotations[settings.Bounds]
	}
	return false
}

func findJSONFiles(dir string) ([]string, error) {
	ans := []string{}
	f := func(path string, fi os.FileInfo, _ error) error {
		if fi.IsDir() {
			return nil
		}
		if strings.HasSuffix(path, ".json") {
			ans = append(ans, path)
		}
		return nil
	}
	err := filepath.Walk(dir, f)
	return ans, err
}


================================================
FILE: gopls/internal/golang/completion/builtin.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"context"
	"go/ast"
	"go/types"
)

// builtinArgKind determines the expected object kind for a builtin
// argument. It attempts to use the AST hints from builtin.go where
// possible.
func (c *completer) builtinArgKind(ctx context.Context, obj types.Object, call *ast.CallExpr) objKind {
	builtin, err := c.snapshot.BuiltinFile(ctx)
	if err != nil {
		return 0
	}
	exprIdx := exprAtPos(c.pos, call.Args)

	builtinObj := builtin.File.Scope.Lookup(obj.Name())
	if builtinObj == nil {
		return 0
	}
	decl, ok := builtinObj.Decl.(*ast.FuncDecl)
	if !ok || exprIdx >= len(decl.Type.Params.List) {
		return 0
	}

	switch ptyp := decl.Type.Params.List[exprIdx].Type.(type) {
	case *ast.ChanType:
		return kindChan
	case *ast.ArrayType:
		return kindSlice
	case *ast.MapType:
		return kindMap
	case *ast.Ident:
		switch ptyp.Name {
		case "Type":
			switch obj.Name() {
			case "make":
				return kindChan | kindSlice | kindMap
			case "len":
				return kindSlice | kindMap | kindArray | kindString | kindChan
			case "cap":
				return kindSlice | kindArray | kindChan
			}
		}
	}

	return 0
}

// builtinArgType infers the type of an argument to a builtin
// function. parentInf is the inferred type info for the builtin
// call's parent node.
func (c *completer) builtinArgType(obj types.Object, call *ast.CallExpr, parentInf candidateInference) candidateInference {
	var (
		exprIdx = exprAtPos(c.pos, call.Args)

		// Propagate certain properties from our parent's inference.
		inf = candidateInference{
			typeName:  parentInf.typeName,
			modifiers: parentInf.modifiers,
		}
	)

	switch obj.Name() {
	case "append":
		if exprIdx <= 0 {
			// Infer first append() arg type as apparent return type of
			// append().
			inf.objType = parentInf.objType
			if parentInf.variadic {
				inf.objType = types.NewSlice(inf.objType)
			}
			break
		}

		// For non-initial append() args, infer slice type from the first
		// append() arg, or from parent context.
		if len(call.Args) > 0 {
			inf.objType = c.pkg.TypesInfo().TypeOf(call.Args[0])
		}
		if inf.objType == nil {
			inf.objType = parentInf.objType
		}
		if inf.objType == nil {
			break
		}

		inf.objType = deslice(inf.objType)

		// Check if we are completing the variadic append() param.
		inf.variadic = exprIdx == 1 && len(call.Args) <= 2

		// Penalize the first append() argument as a candidate. You
		// don't normally append a slice to itself.
		if sliceChain := objChain(c.pkg.TypesInfo(), call.Args[0]); len(sliceChain) > 0 {
			inf.penalized = append(inf.penalized, penalizedObj{objChain: sliceChain, penalty: 0.9})
		}
	case "delete":
		if exprIdx > 0 && len(call.Args) > 0 {
			// Try to fill in expected type of map key.
			firstArgType := c.pkg.TypesInfo().TypeOf(call.Args[0])
			if firstArgType != nil {
				if mt, ok := firstArgType.Underlying().(*types.Map); ok {
					inf.objType = mt.Key()
				}
			}
		}
	case "copy":
		var t1, t2 types.Type
		if len(call.Args) > 0 {
			t1 = c.pkg.TypesInfo().TypeOf(call.Args[0])
			if len(call.Args) > 1 {
				t2 = c.pkg.TypesInfo().TypeOf(call.Args[1])
			}
		}

		// Fill in expected type of either arg if the other is already present.
		if exprIdx == 1 && t1 != nil {
			inf.objType = t1
		} else if exprIdx == 0 && t2 != nil {
			inf.objType = t2
		}
	case "new":
		inf.typeName.wantTypeName = true
		if parentInf.objType != nil {
			// Expected type for "new" is the de-pointered parent type.
			if ptr, ok := parentInf.objType.Underlying().(*types.Pointer); ok {
				inf.objType = ptr.Elem()
			}
		}
	case "make":
		if exprIdx == 0 {
			inf.typeName.wantTypeName = true
			inf.objType = parentInf.objType
		} else {
			inf.objType = types.Typ[types.UntypedInt]
		}
	}

	return inf
}


================================================
FILE: gopls/internal/golang/completion/completion.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package completion provides core functionality for code completion in Go
// editors and tools.
package completion

import (
	"context"
	"fmt"
	"go/ast"
	"go/constant"
	"go/parser"
	"go/printer"
	"go/scanner"
	"go/token"
	"go/types"
	"math"
	"slices"
	"sort"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"
	"unicode"

	"golang.org/x/sync/errgroup"
	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/fuzzy"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

// A CompletionItem represents a possible completion suggested by the algorithm.
type CompletionItem struct {

	// Invariant: CompletionItem does not refer to syntax or types.

	// Label is the primary text the user sees for this completion item.
	Label string

	// Detail is supplemental information to present to the user.
	// This often contains the type or return type of the completion item.
	Detail string

	// InsertText is the text to insert if this item is selected.
	// Any of the prefix that has already been typed is not trimmed.
	// The insert text does not contain snippets.
	InsertText string

	Kind       protocol.CompletionItemKind
	Tags       []protocol.CompletionItemTag
	Deprecated bool // Deprecated, prefer Tags if available

	// An optional array of additional TextEdits that are applied when
	// selecting this completion.
	//
	// Additional text edits should be used to change text unrelated to the current cursor position
	// (for example adding an import statement at the top of the file if the completion item will
	// insert an unqualified type).
	AdditionalTextEdits []protocol.TextEdit

	// Depth is how many levels were searched to find this completion.
	// For example when completing "foo<>", "fooBar" is depth 0, and
	// "fooBar.Baz" is depth 1.
	Depth int

	// Score is the internal relevance score.
	// A higher score indicates that this completion item is more relevant.
	Score float64

	// snippet is the LSP snippet for the completion item. The LSP
	// specification contains details about LSP snippets. For example, a
	// snippet for a function with the following signature:
	//
	//     func foo(a, b, c int)
	//
	// would be:
	//
	//     foo(${1:a int}, ${2: b int}, ${3: c int})
	//
	// If Placeholders is false in the CompletionOptions, the above
	// snippet would instead be:
	//
	//     foo(${1:})
	snippet *snippet.Builder

	// Documentation is the documentation for the completion item.
	Documentation string

	// isSlice reports whether the underlying type of the object
	// from which this candidate was derived is a slice.
	// (Used to complete append() calls.)
	isSlice bool
}

// completionOptions holds completion specific configuration.
type completionOptions struct {
	unimported            bool
	documentation         bool
	fullDocumentation     bool
	placeholders          bool
	snippets              bool
	postfix               bool
	matcher               settings.Matcher
	budget                time.Duration
	completeFunctionCalls bool
}

// Snippet is a convenience returns the snippet if available, otherwise
// the InsertText.
// used for an item, depending on if the callee wants placeholders or not.
func (i *CompletionItem) Snippet() string {
	if i.snippet != nil {
		return i.snippet.String()
	}
	return i.InsertText
}

// addConversion wraps the existing completionItem in a conversion expression.
// Only affects the receiver's InsertText and snippet fields, not the Label.
// An empty conv argument has no effect.
func (i *CompletionItem) addConversion(c *completer, conv conversionEdits) {
	if conv.prefix != "" {
		// If we are in a selector, add an edit to place prefix before selector.
		if sel := enclosingSelector(c.path, c.pos); sel != nil {
			edits, err := c.editText(sel.Pos(), sel.Pos(), conv.prefix)
			if err != nil {
				// safetoken failed: invalid token.Pos information in AST.
				return
			}
			i.AdditionalTextEdits = append(i.AdditionalTextEdits, edits...)
		} else {
			// If there is no selector, just stick the prefix at the start.
			i.InsertText = conv.prefix + i.InsertText
			i.snippet.PrependText(conv.prefix)
		}
	}

	if conv.suffix != "" {
		i.InsertText += conv.suffix
		i.snippet.WriteText(conv.suffix)
	}
}

// Scoring constants are used for weighting the relevance of different candidates.
const (
	// lowScore indicates an irrelevant or not useful completion item.
	lowScore float64 = 0.01

	// stdScore is the base score for all completion items.
	stdScore float64 = 1.0

	// highScore indicates a very relevant completion item.
	highScore float64 = 10.0
)

// matcher matches a candidate's label against the user input. The
// returned score reflects the quality of the match. A score of zero
// indicates no match, and a score of one means a perfect match.
type matcher interface {
	Score(candidateLabel string) (score float32)
}

// prefixMatcher implements case sensitive prefix matching.
type prefixMatcher string

func (pm prefixMatcher) Score(candidateLabel string) float32 {
	if strings.HasPrefix(candidateLabel, string(pm)) {
		return 1
	}
	return -1
}

// insensitivePrefixMatcher implements case insensitive prefix matching.
type insensitivePrefixMatcher string

func (ipm insensitivePrefixMatcher) Score(candidateLabel string) float32 {
	if strings.HasPrefix(strings.ToLower(candidateLabel), string(ipm)) {
		return 1
	}
	return -1
}

// completer contains the necessary information for a single completion request.
type completer struct {
	snapshot *cache.Snapshot
	pkg      *cache.Package
	qual     types.Qualifier          // for qualifying typed expressions
	mq       golang.MetadataQualifier // for syntactic qualifying
	opts     *completionOptions

	// completionContext contains information about the trigger for this
	// completion request.
	completionContext completionContext

	// fh is a handle to the file associated with this completion request.
	fh file.Handle

	// filename is the name of the file associated with this completion request.
	filename string

	// pgf is the AST of the file associated with this completion request.
	pgf *parsego.File // debugging

	// goversion is the version of Go in force in the file, as
	// defined by x/tools/internal/versions. Empty if unknown.
	// Since go1.22 it should always be known.
	goversion string

	// pos is the position at which the request was triggered.
	pos token.Pos

	// path is the path of AST nodes enclosing the position.
	path []ast.Node

	// seen is the map that ensures we do not return duplicate results.
	seen map[types.Object]bool

	// items is the list of completion items returned.
	items []CompletionItem

	// completionCallbacks is a list of callbacks to collect completions that
	// require expensive operations. This includes operations where we search
	// through the entire module cache.
	completionCallbacks []func(context.Context, *imports.Options) error

	// surrounding describes the identifier surrounding the position.
	surrounding *Selection

	// inference contains information we've inferred about ideal
	// candidates such as the candidate's type.
	inference candidateInference

	// enclosingFunc contains information about the function enclosing
	// the position.
	enclosingFunc *funcInfo

	// enclosingCompositeLiteral contains information about the composite literal
	// enclosing the position.
	enclosingCompositeLiteral *compLitInfo

	// deepState contains the current state of our deep completion search.
	deepState deepCompletionState

	// matcher matches the candidates against the surrounding prefix.
	matcher matcher

	// methodSetCache caches the [types.NewMethodSet] call, which is relatively
	// expensive and can be called many times for the same type while searching
	// for deep completions.
	// TODO(adonovan): use [typeutil.MethodSetCache], which exists for this purpose.
	methodSetCache map[methodSetKey]*types.MethodSet

	// tooNewSymbolsCache is a cache of
	// [typesinternal.TooNewStdSymbols], recording for each std
	// package which of its exported symbols are too new for
	// the version of Go in force in the completion file.
	// (The value is the minimum version in the form "go1.%d".)
	tooNewSymbolsCache map[*types.Package]map[types.Object]string

	// mapper converts the positions in the file from which the completion originated.
	mapper *protocol.Mapper

	// startTime is when we started processing this completion request. It does
	// not include any time the request spent in the queue.
	//
	// Note: in CL 503016, startTime move to *after* type checking, but it was
	// subsequently determined that it was better to keep setting it *before*
	// type checking, so that the completion budget best approximates the user
	// experience. See golang/go#62665 for more details.
	startTime time.Time

	// scopes contains all scopes defined by nodes in our path,
	// including nil values for nodes that don't defined a scope. It
	// also includes our package scope and the universal scope at the
	// end.
	//
	// (It is tempting to replace this with fileScope.Innermost(pos)
	// and simply follow the Scope.Parent chain, but we need to
	// preserve the pairwise association of scopes[i] and path[i]
	// because there is no way to get from the Scope to the Node.)
	scopes []*types.Scope
}

// tooNew reports whether obj is a standard library symbol that is too
// new for the specified Go version.
func (c *completer) tooNew(obj types.Object) bool {
	pkg := obj.Pkg()
	if pkg == nil {
		return false // unsafe.Pointer or error.Error
	}
	disallowed, ok := c.tooNewSymbolsCache[pkg]
	if !ok {
		disallowed = typesinternal.TooNewStdSymbols(pkg, c.goversion)
		c.tooNewSymbolsCache[pkg] = disallowed
	}
	return disallowed[obj] != ""
}

// funcInfo holds info about a function object.
type funcInfo struct {
	// sig is the function declaration enclosing the position.
	sig *types.Signature

	// body is the function's body.
	body *ast.BlockStmt
}

type compLitInfo struct {
	// cl is the *ast.CompositeLit enclosing the position.
	cl *ast.CompositeLit

	// clType is the type of cl.
	clType types.Type

	// kv is the *ast.KeyValueExpr enclosing the position, if any.
	kv *ast.KeyValueExpr

	// inKey is true if we are certain the position is in the key side
	// of a key-value pair.
	inKey bool

	// maybeInFieldName is true if inKey is false and it is possible
	// we are completing a struct field name. For example,
	// "SomeStruct{<>}" will be inKey=false, but maybeInFieldName=true
	// because we _could_ be completing a field name.
	maybeInFieldName bool
}

type importInfo struct {
	importPath string
	name       string
}

type methodSetKey struct {
	typ         types.Type
	addressable bool
}

type completionContext struct {
	// triggerCharacter is the character used to trigger completion at current
	// position, if any.
	triggerCharacter string

	// triggerKind is information about how a completion was triggered.
	triggerKind protocol.CompletionTriggerKind

	// commentCompletion is true if we are completing a comment.
	commentCompletion bool

	// packageCompletion is true if we are completing a package name.
	packageCompletion bool
}

// A Selection represents the cursor position and surrounding identifier.
type Selection struct {
	content            string // invariant: 0<=cursor-start<=len(content)
	tokFile            *token.File
	start, end, cursor token.Pos // relative to rng.TokFile
	mapper             *protocol.Mapper
}

// Range returns the surrounding identifier's protocol.Range.
func (p Selection) Range() (protocol.Range, error) {
	return p.mapper.PosRange(p.tokFile, p.start, p.end)
}

// PrefixRange returns the protocol.Range of the prefix of the selection.
func (p Selection) PrefixRange() (protocol.Range, error) {
	return p.mapper.PosRange(p.tokFile, p.start, p.cursor)
}

func (p Selection) Prefix() string {
	return p.content[:p.cursor-p.start]
}

func (p Selection) Suffix() string {
	return p.content[p.cursor-p.start:]
}

// check that Prefix and Suffix will succeed (golang/go#77050)
// at the time a Selection is constructed.
func (p Selection) check() {
	offset := int(p.cursor - p.start)
	// separate the cases so that they are distinguished in the stack trace
	if offset < 0 {
		bug.Reportf("Selection invariant, len(content)=%d cursor=%d start=%d", len(p.content), p.cursor, p.start)
	}
	if offset > len(p.content) {
		bug.Reportf("Selection invariant, len(content)=%d cursor=%d start=%d", len(p.content), p.cursor, p.start)
	}
}

func (c *completer) setSurrounding(ident *ast.Ident) {
	if c.surrounding != nil {
		return
	}
	if !(ident.Pos() <= c.pos && c.pos <= ident.End()) {
		return
	}

	c.surrounding = &Selection{
		content: ident.Name,
		cursor:  c.pos,
		// Overwrite the prefix only.
		tokFile: c.pgf.Tok,
		start:   ident.Pos(),
		end:     ident.End(),
		mapper:  c.mapper,
	}
	c.surrounding.check()

	c.setMatcherFromPrefix(c.surrounding.Prefix())
}

func (c *completer) setMatcherFromPrefix(prefix string) {
	switch c.opts.matcher {
	case settings.Fuzzy:
		c.matcher = fuzzy.NewMatcher(prefix)
	case settings.CaseSensitive:
		c.matcher = prefixMatcher(prefix)
	default:
		c.matcher = insensitivePrefixMatcher(strings.ToLower(prefix))
	}
}

func (c *completer) getSurrounding() *Selection {
	if c.surrounding == nil {
		c.surrounding = &Selection{
			content: "",
			cursor:  c.pos,
			tokFile: c.pgf.Tok,
			start:   c.pos,
			end:     c.pos,
			mapper:  c.mapper,
		}
		c.surrounding.check()
	}
	return c.surrounding
}

// candidate represents a completion candidate.
type candidate struct {
	// obj is the types.Object to complete to.
	// TODO(adonovan): eliminate dependence on go/types throughout this struct.
	// See comment in (*completer).selector for explanation.
	obj types.Object

	// score is used to rank candidates.
	score float64

	// name is the deep object name path, e.g. "foo.bar"
	name string

	// detail is additional information about this item. If not specified,
	// defaults to type string for the object.
	detail string

	// path holds the path from the search root (excluding the candidate
	// itself) for a deep candidate.
	path []types.Object

	// pathInvokeMask is a bit mask tracking whether each entry in path
	// should be formatted with "()" (i.e. whether it is a function
	// invocation).
	pathInvokeMask uint16

	// mods contains modifications that should be applied to the
	// candidate when inserted. For example, "foo" may be inserted as
	// "*foo" or "foo()".
	mods []typeModKind

	// addressable is true if a pointer can be taken to the candidate.
	addressable bool

	// convertTo is a type that this candidate should be cast to. For
	// example, if convertTo is float64, "foo" should be formatted as
	// "float64(foo)".
	convertTo types.Type

	// imp is the import that needs to be added to this package in order
	// for this candidate to be valid. nil if no import needed.
	imp *importInfo
}

func (c candidate) hasMod(mod typeModKind) bool {
	return slices.Contains(c.mods, mod)
}

// Completion returns a list of possible candidates for completion, given a
// a file and a position.
//
// The selection is computed based on the preceding identifier and can be used by
// the client to score the quality of the completion. For instance, some clients
// may tolerate imperfect matches as valid completion results, since users may make typos.
func Completion(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, protoPos protocol.Position, protoContext protocol.CompletionContext) ([]CompletionItem, *Selection, error) {
	ctx, done := event.Start(ctx, "completion.Completion")
	defer done()

	startTime := time.Now()

	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil || !pgf.File.Package.IsValid() {
		// Invalid package declaration
		//
		// If we can't parse this file or find position for the package
		// keyword, it may be missing a package declaration. Try offering
		// suggestions for the package declaration.
		// Note that this would be the case even if the keyword 'package' is
		// present but no package name exists.
		items, surrounding, innerErr := packageClauseCompletions(ctx, snapshot, fh, protoPos)
		if innerErr != nil {
			// return the error for GetParsedFile since it's more relevant in this situation.
			return nil, nil, fmt.Errorf("getting file %s for Completion: %v (package completions: %v)", fh.URI(), err, innerErr)
		}
		return items, surrounding, nil
	}

	pos, err := pgf.PositionPos(protoPos)
	if err != nil {
		return nil, nil, err
	}
	// Completion is based on what precedes the cursor.
	// Find the path to the position before pos.
	path, _ := goastutil.PathEnclosingInterval(pgf.File, pos-1, pos-1)
	if path == nil {
		return nil, nil, fmt.Errorf("cannot find node enclosing position")
	}

	info := pkg.TypesInfo()

	// Check if completion at this position is valid. If not, return early.
	switch n := path[0].(type) {
	case *ast.BasicLit:
		// Skip completion inside literals except for ImportSpec
		if len(path) > 1 {
			if _, ok := path[1].(*ast.ImportSpec); ok {
				break
			}
		}
		return nil, nil, nil
	case *ast.CallExpr:
		if n.Ellipsis.IsValid() && pos > n.Ellipsis && pos <= n.Ellipsis+token.Pos(len("...")) {
			// Don't offer completions inside or directly after "...". For
			// example, don't offer completions at "<>" in "foo(bar...<>").
			return nil, nil, nil
		}
	case *ast.Ident:
		// Don't offer completions for (most) defining identifiers.
		if obj, ok := info.Defs[n]; ok {
			if v, ok := obj.(*types.Var); ok && v.IsField() && v.Embedded() {
				// Allow completion of anonymous fields, since they may reference type
				// names.
			} else if pgf.File.Name == n {
				// Allow package name completion.
			} else {
				// Check if we have special completion for this definition, such as
				// test function name completion.
				ans, sel := definition(path, obj, pgf)
				if ans != nil {
					sort.Slice(ans, func(i, j int) bool {
						return ans[i].Score > ans[j].Score
					})
					return ans, sel, nil
				}

				return nil, nil, nil // No completions.
			}
		}
	}

	// Collect all surrounding scopes, innermost first, inserting
	// nils as needed to preserve the correspondence with path[i].
	var scopes []*types.Scope
	for _, n := range path {
		switch node := n.(type) {
		case *ast.FuncDecl:
			n = node.Type
		case *ast.FuncLit:
			n = node.Type
		}
		scopes = append(scopes, info.Scopes[n])
	}
	scopes = append(scopes, pkg.Types().Scope(), types.Universe)

	opts := snapshot.Options()
	c := &completer{
		pkg:      pkg,
		snapshot: snapshot,
		qual:     typesinternal.FileQualifier(pgf.File, pkg.Types()),
		mq:       golang.MetadataQualifierForFile(snapshot, pgf.File, pkg.Metadata()),
		completionContext: completionContext{
			triggerCharacter: protoContext.TriggerCharacter,
			triggerKind:      protoContext.TriggerKind,
		},
		fh:                        fh,
		filename:                  fh.URI().Path(),
		pgf:                       pgf,
		goversion:                 versions.FileVersion(info, pgf.File), // may be "" => no version check
		path:                      path,
		pos:                       pos,
		seen:                      make(map[types.Object]bool),
		enclosingFunc:             enclosingFunction(path, info),
		enclosingCompositeLiteral: enclosingCompositeLiteral(path, pos, info),
		deepState: deepCompletionState{
			enabled: opts.DeepCompletion,
		},
		opts: &completionOptions{
			matcher:               opts.Matcher,
			unimported:            opts.CompleteUnimported,
			documentation:         opts.CompletionDocumentation && opts.HoverKind != settings.NoDocumentation,
			fullDocumentation:     opts.HoverKind == settings.FullDocumentation,
			placeholders:          opts.UsePlaceholders,
			budget:                opts.CompletionBudget,
			snippets:              opts.InsertTextFormat == protocol.SnippetTextFormat,
			postfix:               opts.ExperimentalPostfixCompletions,
			completeFunctionCalls: opts.CompleteFunctionCalls,
		},
		// default to a matcher that always matches
		matcher:            prefixMatcher(""),
		methodSetCache:     make(map[methodSetKey]*types.MethodSet),
		tooNewSymbolsCache: make(map[*types.Package]map[types.Object]string),
		mapper:             pgf.Mapper,
		startTime:          startTime,
		scopes:             scopes,
	}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()

	// Compute the deadline for this operation. Deadline is relative to the
	// search operation, not the entire completion RPC, as the work up until this
	// point depends significantly on how long it took to type-check, which in
	// turn depends on the timing of the request relative to other operations on
	// the snapshot. Including that work in the budget leads to inconsistent
	// results (and realistically, if type-checking took 200ms already, the user
	// is unlikely to be significantly more bothered by e.g. another 100ms of
	// search).
	//
	// Don't overload the context with this deadline, as we don't want to
	// conflate user cancellation (=fail the operation) with our time limit
	// (=stop searching and succeed with partial results).
	var deadline *time.Time
	if c.opts.budget > 0 {
		d := startTime.Add(c.opts.budget)
		deadline = &d
	}

	if surrounding := c.containingIdent(pgf.Src); surrounding != nil {
		c.setSurrounding(surrounding)
	}

	c.inference = expectedCandidate(ctx, c)

	err = c.collectCompletions(ctx)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to collect completions: %v", err)
	}

	// Deep search collected candidates and their members for more candidates.
	c.deepSearch(ctx, 1, deadline)

	// At this point we have a sufficiently complete set of results, and want to
	// return as close to the completion budget as possible. Previously, we
	// avoided cancelling the context because it could result in partial results
	// for e.g. struct fields. At this point, we have a minimal valid set of
	// candidates, and so truncating due to context cancellation is acceptable.
	if c.opts.budget > 0 {
		timeoutDuration := time.Until(c.startTime.Add(c.opts.budget))
		ctx, cancel = context.WithTimeout(ctx, timeoutDuration)
		defer cancel()
	}

	for _, callback := range c.completionCallbacks {
		if deadline == nil || time.Now().Before(*deadline) {
			if err := c.snapshot.RunProcessEnvFunc(ctx, callback); err != nil {
				return nil, nil, fmt.Errorf("failed to run goimports callback: %v", err)
			}
		}
	}

	// Search candidates populated by expensive operations like
	// unimportedMembers etc. for more completion items.
	c.deepSearch(ctx, 0, deadline)

	// Statement candidates offer an entire statement in certain contexts, as
	// opposed to a single object. Add statement candidates last because they
	// depend on other candidates having already been collected.
	c.addStatementCandidates()

	sortItems(c.items)
	return c.items, c.getSurrounding(), nil
}

// collectCompletions adds possible completion candidates to either the deep
// search queue or completion items directly for different completion contexts.
func (c *completer) collectCompletions(ctx context.Context) error {
	// Inside import blocks, return completions for unimported packages.
	for _, importSpec := range c.pgf.File.Imports {
		if !(importSpec.Path.Pos() <= c.pos && c.pos <= importSpec.Path.End()) {
			continue
		}
		return c.populateImportCompletions(importSpec)
	}

	// Inside comments, offer completions for the name of the relevant symbol.
	for _, comment := range c.pgf.File.Comments {
		if comment.Pos() < c.pos && c.pos <= comment.End() {
			c.populateCommentCompletions(comment)
			return nil
		}
	}

	// Struct literals are handled entirely separately.
	if wantStructFieldCompletions(c.enclosingCompositeLiteral) {
		// If we are definitely completing a struct field name, deep completions
		// don't make sense.
		if c.enclosingCompositeLiteral.inKey {
			c.deepState.enabled = false
		}
		return c.structLiteralFieldName(ctx)
	}

	if lt := c.wantLabelCompletion(); lt != labelNone {
		c.labels(lt)
		return nil
	}

	if c.emptySwitchStmt() {
		// Empty switch statements only admit "default" and "case" keywords.
		c.addKeywordItems(map[string]bool{}, highScore, CASE, DEFAULT)
		return nil
	}

	switch n := c.path[0].(type) {
	case *ast.Ident:
		if c.pgf.File.Name == n {
			return c.packageNameCompletions(ctx, c.fh.URI(), n)
		} else if sel, ok := c.path[1].(*ast.SelectorExpr); ok && sel.Sel == n {
			// We are in the Sel part of a selector (e.g. x.‸sel or x.sel‸).
			return c.selector(ctx, sel)
		}
		return c.lexical(ctx)

	case *ast.TypeAssertExpr:
		// The function name hasn't been typed yet, but the parens are there:
		//   recv.‸(arg)
		// Create a fake selector expression.

		// The name "_" is the convention used by go/parser to represent phantom
		// selectors.
		sel := &ast.Ident{NamePos: n.X.End() + token.Pos(len(".")), Name: "_"}
		return c.selector(ctx, &ast.SelectorExpr{X: n.X, Sel: sel})

	case *ast.SelectorExpr:
		// We are in the X part of a selector (x‸.sel),
		// or after the dot with a fixed/phantom Sel (x.‸_).
		return c.selector(ctx, n)

	case *ast.BadDecl, *ast.File:
		// At the file scope, only keywords are allowed.
		c.addKeywordCompletions()

	default:
		// fallback to lexical completions
		return c.lexical(ctx)
	}

	return nil
}

// containingIdent returns the *ast.Ident containing pos, if any. It
// synthesizes an *ast.Ident to allow completion in the face of
// certain syntax errors.
func (c *completer) containingIdent(src []byte) *ast.Ident {
	// In the normal case, our leaf AST node is the identifier being completed.
	if ident, ok := c.path[0].(*ast.Ident); ok {
		return ident
	}

	pos, tkn, lit := c.scanToken(src)
	if !pos.IsValid() {
		return nil
	}

	fakeIdent := &ast.Ident{Name: lit, NamePos: pos}
	if _, isBadDecl := c.path[0].(*ast.BadDecl); isBadDecl {
		// You don't get *ast.Idents at the file level, so look for bad
		// decls and use the manually extracted token.
		return fakeIdent
	} else if c.emptySwitchStmt() {
		// Only keywords are allowed in empty switch statements.
		// *ast.Idents are not parsed, so we must use the manually
		// extracted token.
		return fakeIdent
	} else if tkn.IsKeyword() {
		// Otherwise, manually extract the prefix if our containing token
		// is a keyword. This improves completion after an "accidental
		// keyword", e.g. completing to "variance" in "someFunc(var<>)".
		return fakeIdent
	} else if block, ok := c.path[0].(*ast.BlockStmt); ok && len(block.List) != 0 {
		last := block.List[len(block.List)-1]
		// Handle incomplete AssignStmt with multiple left-hand vars:
		//     var left, right int
		//     left, ri‸                    -> "right"
		if expr, ok := last.(*ast.ExprStmt); ok &&
			(is[*ast.Ident](expr.X) ||
				is[*ast.SelectorExpr](expr.X) ||
				is[*ast.IndexExpr](expr.X) ||
				is[*ast.StarExpr](expr.X)) {
			return fakeIdent
		}
	}

	return nil
}

// scanToken scans pgh's contents for the token containing pos.
func (c *completer) scanToken(contents []byte) (token.Pos, token.Token, string) {
	tok := c.pkg.FileSet().File(c.pos)

	var s scanner.Scanner
	// TODO(adonovan): fix! this mutates the token.File borrowed from c.pkg,
	// calling AddLine and AddLineColumnInfo. Not sound!
	s.Init(tok, contents, nil, 0)
	for {
		tknPos, tkn, lit := s.Scan()
		if tkn == token.EOF || tknPos >= c.pos {
			return token.NoPos, token.ILLEGAL, ""
		}

		if len(lit) > 0 && tknPos <= c.pos && c.pos <= tknPos+token.Pos(len(lit)) {
			return tknPos, tkn, lit
		}
	}
}

func sortItems(items []CompletionItem) {
	sort.SliceStable(items, func(i, j int) bool {
		// Sort by score first.
		if items[i].Score != items[j].Score {
			return items[i].Score > items[j].Score
		}

		// Then sort by label so order stays consistent. This also has the
		// effect of preferring shorter candidates.
		return items[i].Label < items[j].Label
	})
}

// emptySwitchStmt reports whether pos is in an empty switch or select
// statement.
func (c *completer) emptySwitchStmt() bool {
	block, ok := c.path[0].(*ast.BlockStmt)
	if !ok || len(block.List) > 0 || len(c.path) == 1 {
		return false
	}

	switch c.path[1].(type) {
	case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
		return true
	default:
		return false
	}
}

// populateImportCompletions yields completions for an import path around the cursor.
//
// Completions are suggested at the directory depth of the given import path so
// that we don't overwhelm the user with a large list of possibilities. As an
// example, a completion for the prefix "golang" results in "golang.org/".
// Completions for "golang.org/" yield its subdirectories
// (i.e. "golang.org/x/"). The user is meant to accept completion suggestions
// until they reach a complete import path.
func (c *completer) populateImportCompletions(searchImport *ast.ImportSpec) error {
	if !strings.HasPrefix(searchImport.Path.Value, `"`) {
		return nil
	}

	// deepSearch is not valuable for import completions.
	c.deepState.enabled = false

	importPath := searchImport.Path.Value

	// Extract the text between the quotes (if any) in an import spec.
	// prefix is the part of import path before the cursor.
	prefixEnd := c.pos - searchImport.Path.Pos()
	prefix := strings.Trim(importPath[:prefixEnd], `"`)

	// The number of directories in the import path gives us the depth at
	// which to search.
	depth := len(strings.Split(prefix, "/")) - 1

	content := importPath
	start, end := searchImport.Path.Pos(), searchImport.Path.End()
	namePrefix, nameSuffix := `"`, `"`
	// If a starting quote is present, adjust surrounding to either after the
	// cursor or after the first slash (/), except if cursor is at the starting
	// quote. Otherwise we provide a completion including the starting quote.
	if strings.HasPrefix(importPath, `"`) && c.pos > searchImport.Path.Pos() {
		content = content[1:]
		start++
		if depth > 0 {
			// Adjust textEdit start to replacement range. For ex: if current
			// path was "golang.or/x/to<>ols/internal/", where <> is the cursor
			// position, start of the replacement range would be after
			// "golang.org/x/".
			path := strings.SplitAfter(prefix, "/")
			numChars := len(strings.Join(path[:len(path)-1], ""))
			content = content[numChars:]
			start += token.Pos(numChars)
		}
		namePrefix = ""
	}

	// We won't provide an ending quote if one is already present, except if
	// cursor is after the ending quote but still in import spec. This is
	// because cursor has to be in our textEdit range.
	if strings.HasSuffix(importPath, `"`) && c.pos < searchImport.Path.End() {
		end--
		content = content[:len(content)-1]
		nameSuffix = ""
	}

	c.surrounding = &Selection{
		content: content,
		cursor:  c.pos,
		tokFile: c.pgf.Tok,
		start:   start,
		end:     end,
		mapper:  c.mapper,
	}
	c.surrounding.check()

	seenImports := make(map[string]struct{})
	for _, importSpec := range c.pgf.File.Imports {
		if importSpec.Path.Value == importPath {
			continue
		}
		seenImportPath, err := strconv.Unquote(importSpec.Path.Value)
		if err != nil {
			return err
		}
		seenImports[seenImportPath] = struct{}{}
	}

	var mu sync.Mutex // guard c.items locally, since searchImports is called in parallel
	seen := make(map[string]struct{})
	searchImports := func(pkg imports.ImportFix) {
		path := pkg.StmtInfo.ImportPath
		if _, ok := seenImports[path]; ok {
			return
		}

		// Any package path containing fewer directories than the search
		// prefix is not a match.
		pkgDirList := strings.Split(path, "/")
		if len(pkgDirList) < depth+1 {
			return
		}
		pkgToConsider := strings.Join(pkgDirList[:depth+1], "/")

		name := pkgDirList[depth]
		// if we're adding an opening quote to completion too, set name to full
		// package path since we'll need to overwrite that range.
		if namePrefix == `"` {
			name = pkgToConsider
		}

		score := pkg.Relevance
		if len(pkgDirList)-1 == depth {
			score *= highScore
		} else {
			// For incomplete package paths, add a terminal slash to indicate that the
			// user should keep triggering completions.
			name += "/"
			pkgToConsider += "/"
		}

		if _, ok := seen[pkgToConsider]; ok {
			return
		}
		seen[pkgToConsider] = struct{}{}

		mu.Lock()
		defer mu.Unlock()

		name = namePrefix + name + nameSuffix
		obj := types.NewPkgName(0, nil, name, types.NewPackage(pkgToConsider, name))
		c.deepState.enqueue(candidate{
			obj:    obj,
			detail: strconv.Quote(pkgToConsider),
			score:  score,
		})
	}

	c.completionCallbacks = append(c.completionCallbacks, func(ctx context.Context, opts *imports.Options) error {
		if err := imports.GetImportPaths(ctx, searchImports, prefix, c.filename, c.pkg.Types().Name(), opts.Env); err != nil {
			return fmt.Errorf("getting import paths: %v", err)
		}
		return nil
	})
	return nil
}

// populateCommentCompletions yields completions for comments preceding or in declarations.
func (c *completer) populateCommentCompletions(comment *ast.CommentGroup) {
	// If the completion was triggered by a period, ignore it. These types of
	// completions will not be useful in comments.
	if c.completionContext.triggerCharacter == "." {
		return
	}

	// Using the comment position find the line after
	file := c.pkg.FileSet().File(comment.End())
	if file == nil {
		return
	}

	// Deep completion doesn't work properly in comments since we don't
	// have a type object to complete further.
	c.deepState.enabled = false
	c.completionContext.commentCompletion = true

	// Documentation isn't useful in comments, since it might end up being the
	// comment itself.
	c.opts.documentation = false

	commentLine := safetoken.Line(file, comment.End())

	// comment is valid, set surrounding as word boundaries around cursor
	c.setSurroundingForComment(comment)

	// Using the next line pos, grab and parse the exported symbol on that line
	for _, n := range c.pgf.File.Decls {
		declLine := safetoken.Line(file, n.Pos())
		// if the comment is not in, directly above or on the same line as a declaration
		if declLine != commentLine && declLine != commentLine+1 &&
			!(n.Pos() <= comment.Pos() && comment.End() <= n.End()) {
			continue
		}
		switch node := n.(type) {
		// handle const, vars, and types
		case *ast.GenDecl:
			for _, spec := range node.Specs {
				switch spec := spec.(type) {
				case *ast.ValueSpec:
					for _, name := range spec.Names {
						if name.String() == "_" {
							continue
						}
						obj := c.pkg.TypesInfo().ObjectOf(name)
						c.deepState.enqueue(candidate{obj: obj, score: stdScore})
					}
				case *ast.TypeSpec:
					// add TypeSpec fields to completion
					switch typeNode := spec.Type.(type) {
					case *ast.StructType:
						c.addFieldItems(typeNode.Fields)
					case *ast.FuncType:
						c.addFieldItems(typeNode.Params)
						c.addFieldItems(typeNode.Results)
					case *ast.InterfaceType:
						c.addFieldItems(typeNode.Methods)
					}

					if spec.Name.String() == "_" {
						continue
					}

					obj := c.pkg.TypesInfo().ObjectOf(spec.Name)
					// Type name should get a higher score than fields but not highScore by default
					// since field near a comment cursor gets a highScore
					score := stdScore * 1.1
					// If type declaration is on the line after comment, give it a highScore.
					if declLine == commentLine+1 {
						score = highScore
					}

					c.deepState.enqueue(candidate{obj: obj, score: score})
				}
			}
		// handle functions
		case *ast.FuncDecl:
			c.addFieldItems(node.Recv)
			c.addFieldItems(node.Type.Params)
			c.addFieldItems(node.Type.Results)

			// collect receiver struct fields
			if node.Recv != nil {
				fn, ok := c.pkg.TypesInfo().Defs[node.Name].(*types.Func)
				if !ok {
					// A duplicate FuncDecl may lack a Defs entry.
					// Avoid panicking in this case; see go.dev/issue/71273.
					continue
				}
				sig := fn.Signature()
				recv := sig.Recv()
				if recv == nil {
					continue // may be nil if ill-typed
				}
				_, named := typesinternal.ReceiverNamed(recv)
				if named != nil {
					if recvStruct, ok := named.Underlying().(*types.Struct); ok {
						for field := range recvStruct.Fields() {
							c.deepState.enqueue(candidate{obj: field, score: lowScore})
						}
					}
				}
			}

			if node.Name.String() == "_" {
				continue
			}

			obj := c.pkg.TypesInfo().ObjectOf(node.Name)
			if obj == nil || obj.Pkg() != nil && obj.Pkg() != c.pkg.Types() {
				continue
			}

			c.deepState.enqueue(candidate{obj: obj, score: highScore})
		}
	}
}

// sets word boundaries surrounding a cursor for a comment
func (c *completer) setSurroundingForComment(comments *ast.CommentGroup) {
	var cursorComment *ast.Comment
	for _, comment := range comments.List {
		if c.pos >= comment.Pos() && c.pos <= comment.End() {
			cursorComment = comment
			break
		}
	}
	// if cursor isn't in the comment
	if cursorComment == nil {
		return
	}

	// index of cursor in comment text
	cursorOffset := int(c.pos - cursorComment.Pos())
	start, end := cursorOffset, cursorOffset
	for start > 0 && isValidIdentifierChar(cursorComment.Text[start-1]) {
		start--
	}
	for end < len(cursorComment.Text) && isValidIdentifierChar(cursorComment.Text[end]) {
		end++
	}

	c.surrounding = &Selection{
		content: cursorComment.Text[start:end],
		cursor:  c.pos,
		tokFile: c.pgf.Tok,
		start:   token.Pos(int(cursorComment.Slash) + start),
		end:     token.Pos(int(cursorComment.Slash) + end),
		mapper:  c.mapper,
	}
	c.surrounding.check()
	c.setMatcherFromPrefix(c.surrounding.Prefix())
}

// isValidIdentifierChar returns true if a byte is a valid go identifier
// character, i.e. unicode letter or digit or underscore.
func isValidIdentifierChar(char byte) bool {
	charRune := rune(char)
	return unicode.In(charRune, unicode.Letter, unicode.Digit) || char == '_'
}

// adds struct fields, interface methods, function declaration fields to completion
func (c *completer) addFieldItems(fields *ast.FieldList) {
	// TODO: in golang/go#72828, we get here with a nil surrounding.
	// This indicates a logic bug elsewhere: we should only be interrogating the
	// surrounding if it is set.
	if fields == nil || c.surrounding == nil {
		return
	}

	cursor := c.surrounding.cursor
	for _, field := range fields.List {
		for _, name := range field.Names {
			if name.String() == "_" {
				continue
			}
			obj := c.pkg.TypesInfo().ObjectOf(name)
			if obj == nil {
				continue
			}

			// if we're in a field comment/doc, score that field as more relevant
			score := stdScore
			if field.Comment != nil && field.Comment.Pos() <= cursor && cursor <= field.Comment.End() {
				score = highScore
			} else if field.Doc != nil && field.Doc.Pos() <= cursor && cursor <= field.Doc.End() {
				score = highScore
			}

			c.deepState.enqueue(candidate{obj: obj, score: score})
		}
	}
}

func wantStructFieldCompletions(enclosingCl *compLitInfo) bool {
	if enclosingCl == nil {
		return false
	}
	return is[*types.Struct](enclosingCl.clType) && (enclosingCl.inKey || enclosingCl.maybeInFieldName)
}

func (c *completer) wantTypeName() bool {
	return !c.completionContext.commentCompletion && c.inference.typeName.wantTypeName
}

// See https://golang.org/issue/36001. Unimported completions are expensive.
const (
	maxUnimportedPackageNames = 5
	unimportedMemberTarget    = 100
)

// selector finds completions for the specified selector expression.
//
// The caller should ensure that sel.X has type information,
// even if sel is synthetic.
func (c *completer) selector(ctx context.Context, sel *ast.SelectorExpr) error {
	c.inference.objChain = objChain(c.pkg.TypesInfo(), sel.X)

	// True selector?
	if tv, ok := c.pkg.TypesInfo().Types[sel.X]; ok {
		c.methodsAndFields(tv.Type, tv.Addressable(), nil, c.deepState.enqueue)
		c.addPostfixSnippetCandidates(ctx, sel)
		return nil
	}

	id, ok := sel.X.(*ast.Ident)
	if !ok {
		return nil
	}

	// Treat sel as a qualified identifier.
	var filter func(*metadata.Package) bool
	needImport := false
	if pkgName, ok := c.pkg.TypesInfo().Uses[id].(*types.PkgName); ok {
		// Qualified identifier with import declaration.
		imp := pkgName.Imported()

		// Known direct dependency? Expand using type information.
		if _, ok := c.pkg.Metadata().DepsByPkgPath[golang.PackagePath(imp.Path())]; ok {
			c.packageMembers(imp, stdScore, nil, c.deepState.enqueue)
			return nil
		}

		// Imported declaration with missing type information.
		// Fall through to shallow completion of unimported package members.
		// Match candidate packages by path.
		filter = func(mp *metadata.Package) bool {
			return strings.TrimPrefix(string(mp.PkgPath), "vendor/") == imp.Path()
		}
	} else {
		// Qualified identifier without import declaration.
		// Match candidate packages by name.
		filter = func(mp *metadata.Package) bool {
			return string(mp.Name) == id.Name
		}
		needImport = true
	}

	// Search unimported packages.
	if !c.opts.unimported {
		return nil // feature disabled
	}

	// -- completion of symbols in unimported packages --

	// use new code for unimported completions, if flag allows it
	if c.snapshot.Options().ImportsSource == settings.ImportsSourceGopls {
		// The user might have typed strings.TLower, so id.Name==strings, sel.Sel.Name == TLower,
		// but the cursor might be inside TLower, so adjust the prefix
		prefix := sel.Sel.Name
		if c.surrounding != nil {
			if c.surrounding.content != sel.Sel.Name {
				bug.Reportf("unexpected surrounding: %q != %q", c.surrounding.content, sel.Sel.Name)
			} else {
				prefix = sel.Sel.Name[:c.surrounding.cursor-c.surrounding.start]
			}
		}
		c.unimported(ctx, metadata.PackageName(id.Name), prefix)
		return nil

	}

	// The deep completion algorithm is exceedingly complex and
	// deeply coupled to the now obsolete notions that all
	// token.Pos values can be interpreted by as a single FileSet
	// belonging to the Snapshot and that all types.Object values
	// are canonicalized by a single types.Importer mapping.
	// These invariants are no longer true now that gopls uses
	// an incremental approach, parsing and type-checking each
	// package separately.
	//
	// Consequently, completion of symbols defined in packages that
	// are not currently imported by the query file cannot use the
	// deep completion machinery which is based on type information.
	// Instead it must use only syntax information from a quick
	// parse of top-level declarations (but not function bodies).
	//
	// TODO(adonovan): rewrite the deep completion machinery to
	// not assume global Pos/Object realms and then use export
	// data instead of the quick parse approach taken here.

	// First, we search among packages in the forward transitive
	// closure of the workspace.
	// We'll use a fast parse to extract package members
	// from those that match the name/path criterion.
	all, err := c.snapshot.AllMetadata(ctx)
	if err != nil {
		return err
	}
	known := make(map[golang.PackagePath]*metadata.Package)
	for _, mp := range all {
		if mp.Name == "main" {
			continue // not importable
		}
		if mp.IsIntermediateTestVariant() {
			continue
		}
		// The only test variant we admit is "p [p.test]"
		// when we are completing within "p_test [p.test]",
		// as in that case we would like to offer completions
		// of the test variants' additional symbols.
		if mp.ForTest != "" && c.pkg.Metadata().PkgPath != mp.ForTest+"_test" {
			continue
		}
		if !filter(mp) {
			continue
		}
		// Prefer previous entry unless this one is its test variant.
		if mp.ForTest != "" || known[mp.PkgPath] == nil {
			known[mp.PkgPath] = mp
		}
	}

	paths := make([]string, 0, len(known))
	for path := range known {
		paths = append(paths, string(path))
	}

	// Rank import paths as goimports would.
	var relevances map[string]float64
	if len(paths) > 0 {
		if err := c.snapshot.RunProcessEnvFunc(ctx, func(ctx context.Context, opts *imports.Options) error {
			var err error
			relevances, err = imports.ScoreImportPaths(ctx, opts.Env, paths)
			return err
		}); err != nil {
			return err
		}
		sort.Slice(paths, func(i, j int) bool {
			return relevances[paths[i]] > relevances[paths[j]]
		})
	}

	// quickParse does a quick parse of a single file of package m,
	// extracts exported package members and adds candidates to c.items.
	// TODO(rfindley): synchronizing access to c here does not feel right.
	// Consider adding a concurrency-safe API for completer.
	var cMu sync.Mutex // guards c.items and c.matcher
	var enough int32   // atomic bool
	quickParse := func(uri protocol.DocumentURI, mp *metadata.Package, tooNew map[string]bool) error {
		if atomic.LoadInt32(&enough) != 0 {
			return nil
		}

		fh, err := c.snapshot.ReadFile(ctx, uri)
		if err != nil {
			return err
		}
		content, err := fh.Content()
		if err != nil {
			return err
		}
		path := string(mp.PkgPath)
		forEachPackageMember(content, func(tok token.Token, id *ast.Ident, fn *ast.FuncDecl) {
			if atomic.LoadInt32(&enough) != 0 {
				return
			}

			if !id.IsExported() {
				return
			}

			if tooNew[id.Name] {
				return // symbol too new for requesting file's Go's version
			}

			cMu.Lock()
			score := c.matcher.Score(id.Name)
			cMu.Unlock()

			if sel.Sel.Name != "_" && score == 0 {
				return // not a match; avoid constructing the completion item below
			}

			// The only detail is the kind and package: `var (from "example.com/foo")`
			// TODO(adonovan): pretty-print FuncDecl.FuncType or TypeSpec.Type?
			// TODO(adonovan): should this score consider the actual c.matcher.Score
			// of the item? How does this compare with the deepState.enqueue path?
			item := CompletionItem{
				Label:      id.Name,
				Detail:     fmt.Sprintf("%s (from %q)", strings.ToLower(tok.String()), mp.PkgPath),
				InsertText: id.Name,
				Score:      float64(score) * unimportedScore(relevances[path]),
			}
			switch tok {
			case token.FUNC:
				item.Kind = protocol.FunctionCompletion
			case token.VAR:
				item.Kind = protocol.VariableCompletion
			case token.CONST:
				item.Kind = protocol.ConstantCompletion
			case token.TYPE:
				// Without types, we can't distinguish Class from Interface.
				item.Kind = protocol.ClassCompletion
			}

			if needImport {
				imp := &importInfo{importPath: path}
				if imports.ImportPathToAssumedName(path) != string(mp.Name) {
					imp.name = string(mp.Name)
				}
				item.AdditionalTextEdits, _ = c.importEdits(imp)
			}

			// For functions, add a parameter snippet.
			if fn != nil {
				paramList := func(list *ast.FieldList) []string {
					var params []string
					if list != nil {
						var cfg printer.Config // slight overkill
						param := func(name string, typ ast.Expr) {
							var buf strings.Builder
							buf.WriteString(name)
							buf.WriteByte(' ')
							cfg.Fprint(&buf, token.NewFileSet(), typ) // ignore error
							params = append(params, buf.String())
						}

						for _, field := range list.List {
							if field.Names != nil {
								for _, name := range field.Names {
									param(name.Name, field.Type)
								}
							} else {
								param("_", field.Type)
							}
						}
					}
					return params
				}

				// Ideally we would eliminate the suffix of type
				// parameters that are redundant with inference
				// from the argument types (#51783), but it's
				// quite fiddly to do using syntax alone.
				// (See inferableTypeParams in format.go.)
				tparams := paramList(fn.Type.TypeParams)
				params := paramList(fn.Type.Params)
				var sn snippet.Builder
				c.functionCallSnippet(id.Name, tparams, params, &sn)
				item.snippet = &sn
			}

			cMu.Lock()
			c.items = append(c.items, item)
			if len(c.items) >= unimportedMemberTarget {
				atomic.StoreInt32(&enough, 1)
			}
			cMu.Unlock()
		})
		return nil
	}

	goversion := c.pkg.TypesInfo().FileVersions[c.pgf.File]

	// Extract the package-level candidates using a quick parse.
	var g errgroup.Group
	for _, path := range paths {
		mp := known[golang.PackagePath(path)]

		// For standard packages, build a filter of symbols that
		// are too new for the requesting file's Go version.
		var tooNew map[string]bool
		if syms, ok := stdlib.PackageSymbols[path]; ok && goversion != "" {
			tooNew = make(map[string]bool)
			for _, sym := range syms {
				if versions.Before(goversion, sym.Version.String()) {
					tooNew[sym.Name] = true
				}
			}
		}

		for _, uri := range mp.CompiledGoFiles {
			g.Go(func() error {
				return quickParse(uri, mp, tooNew)
			})
		}
	}
	if err := g.Wait(); err != nil {
		return err
	}

	// In addition, we search in the module cache using goimports.
	ctx, cancel := context.WithCancel(ctx)
	var mu sync.Mutex
	add := func(pkgExport imports.PackageExport) {
		if ignoreUnimportedCompletion(pkgExport.Fix) {
			return
		}

		mu.Lock()
		defer mu.Unlock()
		// TODO(adonovan): what if the actual package has a vendor/ prefix?
		if _, ok := known[golang.PackagePath(pkgExport.Fix.StmtInfo.ImportPath)]; ok {
			return // We got this one above.
		}

		// Continue with untyped proposals.
		pkg := types.NewPackage(pkgExport.Fix.StmtInfo.ImportPath, pkgExport.Fix.IdentName)
		for _, symbol := range pkgExport.Exports {
			if goversion != "" && versions.Before(goversion, symbol.Version.String()) {
				continue // symbol too new for this file
			}
			score := unimportedScore(pkgExport.Fix.Relevance)
			c.deepState.enqueue(candidate{
				obj:   types.NewVar(0, pkg, symbol.Name, nil),
				score: score,
				imp: &importInfo{
					importPath: pkgExport.Fix.StmtInfo.ImportPath,
					name:       pkgExport.Fix.StmtInfo.Name,
				},
			})
		}
		if len(c.items) >= unimportedMemberTarget {
			cancel()
		}
	}

	c.completionCallbacks = append(c.completionCallbacks, func(ctx context.Context, opts *imports.Options) error {
		defer cancel()
		if err := imports.GetPackageExports(ctx, add, id.Name, c.filename, c.pkg.Types().Name(), opts.Env); err != nil {
			return fmt.Errorf("getting package exports: %v", err)
		}
		return nil
	})
	return nil
}

// unimportedScore returns a score for an unimported package that is generally
// lower than other candidates.
func unimportedScore(relevance float64) float64 {
	return (stdScore + .1*relevance) / 2
}

func (c *completer) packageMembers(pkg *types.Package, score float64, imp *importInfo, cb func(candidate)) {
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		if c.tooNew(obj) {
			continue // std symbol too new for file's Go version
		}
		cb(candidate{
			obj:         obj,
			score:       score,
			imp:         imp,
			addressable: isVar(obj),
		})
	}
}

// ignoreUnimportedCompletion reports whether an unimported completion
// resulting in the given import should be ignored.
func ignoreUnimportedCompletion(fix *imports.ImportFix) bool {
	// golang/go#60062: don't add unimported completion to golang.org/toolchain.
	return fix != nil && strings.HasPrefix(fix.StmtInfo.ImportPath, "golang.org/toolchain")
}

func (c *completer) methodsAndFields(typ types.Type, addressable bool, imp *importInfo, cb func(candidate)) {
	if isStarTestingDotF(typ) {
		// is that a sufficient test? (or is more care needed?)
		if c.fuzz(typ, imp, cb) {
			return
		}
	}

	mset := c.methodSetCache[methodSetKey{typ, addressable}]
	if mset == nil {
		if addressable && !types.IsInterface(typ) && !isPointer(typ) {
			// Add methods of *T, which includes methods with receiver T.
			mset = types.NewMethodSet(types.NewPointer(typ))
		} else {
			// Add methods of T.
			mset = types.NewMethodSet(typ)
		}
		c.methodSetCache[methodSetKey{typ, addressable}] = mset
	}

	for method := range mset.Methods() {
		obj := method.Obj()
		// to the other side of the cb() queue?
		if c.tooNew(obj) {
			continue // std method too new for file's Go version
		}
		cb(candidate{
			obj:         method.Obj(),
			score:       stdScore,
			imp:         imp,
			addressable: addressable || isPointer(typ),
		})
	}

	// Add fields of T.
	eachField(typ, func(v *types.Var) {
		if c.tooNew(v) {
			return // std field too new for file's Go version
		}
		cb(candidate{
			obj:         v,
			score:       stdScore - 0.01,
			imp:         imp,
			addressable: addressable || isPointer(typ),
		})
	})
}

// isStarTestingDotF reports whether typ is *testing.F.
func isStarTestingDotF(typ types.Type) bool {
	// No Unalias, since go test doesn't consider
	// types when enumeratinf test funcs, only syntax.
	ptr, _ := typ.(*types.Pointer)
	if ptr == nil {
		return false
	}
	named, _ := ptr.Elem().(*types.Named)
	if named == nil {
		return false
	}
	obj := named.Obj()
	// obj.Pkg is nil for the error type.
	return obj != nil && obj.Pkg() != nil && obj.Pkg().Path() == "testing" && obj.Name() == "F"
}

// lexical finds completions in the lexical environment.
func (c *completer) lexical(ctx context.Context) error {
	var (
		builtinIota = types.Universe.Lookup("iota")
		builtinNil  = types.Universe.Lookup("nil")

		// TODO(rfindley): only allow "comparable" where it is valid (in constraint
		// position or embedded in interface declarations).
		// builtinComparable = types.Universe.Lookup("comparable")
	)

	// Track seen variables to avoid showing completions for shadowed variables.
	// This works since we look at scopes from innermost to outermost.
	seen := make(map[string]struct{})

	// Process scopes innermost first.
	for i, scope := range c.scopes {
		if scope == nil {
			continue
		}

	Names:
		for _, name := range scope.Names() {
			declScope, obj := scope.LookupParent(name, c.pos)
			if declScope != scope {
				continue // scope of name starts after c.pos
			}

			// If obj's type is invalid, find the AST node that defines the lexical block
			// containing the declaration of obj. Don't resolve types for packages.
			if !isPkgName(obj) && !typeIsValid(obj.Type()) {
				// Match the scope to its ast.Node. If the scope is the package scope,
				// use the *ast.File as the starting node.
				var node ast.Node
				if i < len(c.path) {
					node = c.path[i]
				} else if i == len(c.path) { // use the *ast.File for package scope
					node = c.path[i-1]
				}
				if node != nil {
					if resolved := resolveInvalid(c.pkg.FileSet(), obj, node, c.pkg.TypesInfo()); resolved != nil {
						obj = resolved
					}
				}
			}

			// Don't use LHS of decl in RHS.
			for _, ident := range enclosingDeclLHS(c.path) {
				if obj.Pos() == ident.Pos() {
					continue Names
				}
			}

			// Don't suggest "iota" outside of const decls.
			if obj == builtinIota && !c.inConstDecl() {
				continue
			}

			// Rank outer scopes lower than inner.
			score := stdScore * math.Pow(.99, float64(i))

			// Dowrank "nil" a bit so it is ranked below more interesting candidates.
			if obj == builtinNil {
				score /= 2
			}

			// If we haven't already added a candidate for an object with this name.
			if _, ok := seen[obj.Name()]; !ok {
				seen[obj.Name()] = struct{}{}
				c.deepState.enqueue(candidate{
					obj:         obj,
					score:       score,
					addressable: isVar(obj),
				})
			}
		}
	}

	if c.inference.objType != nil {
		if named, ok := types.Unalias(typesinternal.Unpointer(c.inference.objType)).(*types.Named); ok {
			// If we expected a named type, check the type's package for
			// completion items. This is useful when the current file hasn't
			// imported the type's package yet.

			if named.Obj() != nil && named.Obj().Pkg() != nil {
				pkg := named.Obj().Pkg()

				// Make sure the package name isn't already in use by another
				// object, and that this file doesn't import the package yet.
				// TODO(adonovan): what if pkg.Path has vendor/ prefix?
				if _, ok := seen[pkg.Name()]; !ok && pkg != c.pkg.Types() && !alreadyImports(c.pgf.File, golang.ImportPath(pkg.Path())) {
					seen[pkg.Name()] = struct{}{}
					obj := types.NewPkgName(0, nil, pkg.Name(), pkg)
					imp := &importInfo{
						importPath: pkg.Path(),
					}
					if imports.ImportPathToAssumedName(pkg.Path()) != pkg.Name() {
						imp.name = pkg.Name()
					}
					c.deepState.enqueue(candidate{
						obj:   obj,
						score: stdScore,
						imp:   imp,
					})
				}
			}
		}
	}

	if c.opts.unimported {
		if err := c.unimportedPackages(ctx, seen); err != nil {
			return err
		}
	}

	if c.inference.typeName.isTypeParam {
		// If we are completing a type param, offer each structural type.
		// This ensures we suggest "[]int" and "[]float64" for a constraint
		// with type union "[]int | []float64".
		if t, ok := c.inference.objType.(*types.Interface); ok {
			if terms, err := typeparams.InterfaceTermSet(t); err == nil {
				for _, term := range terms {
					c.injectType(ctx, term.Type())
				}
			}
		}
	} else {
		c.injectType(ctx, c.inference.objType)
	}

	// Add keyword completion items appropriate in the current context.
	c.addKeywordCompletions()

	return nil
}

// injectType manufactures candidates based on the given type. This is
// intended for types not discoverable via lexical search, such as
// composite and/or generic types. For example, if the type is "[]int",
// this method makes sure you get candidates "[]int{}" and "[]int"
// (the latter applies when completing a type name).
func (c *completer) injectType(ctx context.Context, t types.Type) {
	if t == nil {
		return
	}

	t = typesinternal.Unpointer(t)

	// If we have an expected type and it is _not_ a named type, handle
	// it specially. Non-named types like "[]int" will never be
	// considered via a lexical search, so we need to directly inject
	// them. Also allow generic types since lexical search does not
	// infer instantiated versions of them.
	if pnt, ok := t.(typesinternal.NamedOrAlias); !ok || pnt.TypeParams().Len() > 0 {
		// If our expected type is "[]int", this will add a literal
		// candidate of "[]int{}".
		c.literal(ctx, t, nil)

		if _, isBasic := t.(*types.Basic); !isBasic {
			// If we expect a non-basic type name (e.g. "[]int"), hack up
			// a named type whose name is literally "[]int". This allows
			// us to reuse our object based completion machinery.
			fakeNamedType := candidate{
				obj:   types.NewTypeName(token.NoPos, nil, types.TypeString(t, c.qual), t),
				score: stdScore,
			}
			// Make sure the type name matches before considering
			// candidate. This cuts down on useless candidates.
			if c.matchingTypeName(&fakeNamedType) {
				c.deepState.enqueue(fakeNamedType)
			}
		}
	}
}

func (c *completer) unimportedPackages(ctx context.Context, seen map[string]struct{}) error {
	var prefix string
	if c.surrounding != nil {
		prefix = c.surrounding.Prefix()
	}

	// Don't suggest unimported packages if we have absolutely nothing
	// to go on.
	if prefix == "" {
		return nil
	}

	count := 0

	// Search the forward transitive closure of the workspace.
	all, err := c.snapshot.AllMetadata(ctx)
	if err != nil {
		return err
	}
	pkgNameByPath := make(map[golang.PackagePath]string)
	var paths []string // actually PackagePaths
	for _, mp := range all {
		if mp.ForTest != "" {
			continue // skip all test variants
		}
		if mp.Name == "main" {
			continue // main is non-importable
		}
		if !strings.HasPrefix(string(mp.Name), prefix) {
			continue // not a match
		}
		paths = append(paths, string(mp.PkgPath))
		pkgNameByPath[mp.PkgPath] = string(mp.Name)
	}

	// Rank candidates using goimports' algorithm.
	var relevances map[string]float64
	if len(paths) != 0 {
		if err := c.snapshot.RunProcessEnvFunc(ctx, func(ctx context.Context, opts *imports.Options) error {
			var err error
			relevances, err = imports.ScoreImportPaths(ctx, opts.Env, paths)
			return err
		}); err != nil {
			return err
		}
	}
	sort.Slice(paths, func(i, j int) bool {
		if relevances[paths[i]] != relevances[paths[j]] {
			return relevances[paths[i]] > relevances[paths[j]]
		}

		// Fall back to lexical sort to keep truncated set of candidates
		// in a consistent order.
		return paths[i] < paths[j]
	})

	for _, path := range paths {
		name := pkgNameByPath[golang.PackagePath(path)]
		if _, ok := seen[name]; ok {
			continue
		}
		imp := &importInfo{
			importPath: path,
		}
		if imports.ImportPathToAssumedName(path) != name {
			imp.name = name
		}
		if count >= maxUnimportedPackageNames {
			return nil
		}
		c.deepState.enqueue(candidate{
			// Pass an empty *types.Package to disable deep completions.
			obj:   types.NewPkgName(0, nil, name, types.NewPackage(path, name)),
			score: unimportedScore(relevances[path]),
			imp:   imp,
		})
		count++
	}

	var mu sync.Mutex
	add := func(pkg imports.ImportFix) {
		if ignoreUnimportedCompletion(&pkg) {
			return
		}
		mu.Lock()
		defer mu.Unlock()
		if _, ok := seen[pkg.IdentName]; ok {
			return
		}
		if _, ok := relevances[pkg.StmtInfo.ImportPath]; ok {
			return
		}

		if count >= maxUnimportedPackageNames {
			return
		}

		// Do not add the unimported packages to seen, since we can have
		// multiple packages of the same name as completion suggestions, since
		// only one will be chosen.
		obj := types.NewPkgName(0, nil, pkg.IdentName, types.NewPackage(pkg.StmtInfo.ImportPath, pkg.IdentName))
		c.deepState.enqueue(candidate{
			obj:   obj,
			score: unimportedScore(pkg.Relevance),
			imp: &importInfo{
				importPath: pkg.StmtInfo.ImportPath,
				name:       pkg.StmtInfo.Name,
			},
		})
		count++
	}

	c.completionCallbacks = append(c.completionCallbacks, func(ctx context.Context, opts *imports.Options) error {
		if err := imports.GetAllCandidates(ctx, add, prefix, c.filename, c.pkg.Types().Name(), opts.Env); err != nil {
			return fmt.Errorf("getting completion candidates: %v", err)
		}
		return nil
	})

	return nil
}

// alreadyImports reports whether f has an import with the specified path.
func alreadyImports(f *ast.File, path golang.ImportPath) bool {
	for _, s := range f.Imports {
		if metadata.UnquoteImportPath(s) == path {
			return true
		}
	}
	return false
}

func (c *completer) inConstDecl() bool {
	for _, n := range c.path {
		if decl, ok := n.(*ast.GenDecl); ok && decl.Tok == token.CONST {
			return true
		}
	}
	return false
}

// structLiteralFieldName finds completions for struct field names inside a struct literal.
func (c *completer) structLiteralFieldName(ctx context.Context) error {
	clInfo := c.enclosingCompositeLiteral

	// Mark fields of the composite literal that have already been set,
	// except for the current field.
	addedFields := make(map[*types.Var]bool)
	for _, el := range clInfo.cl.Elts {
		if kvExpr, ok := el.(*ast.KeyValueExpr); ok {
			if clInfo.kv == kvExpr {
				continue
			}

			if key, ok := kvExpr.Key.(*ast.Ident); ok {
				if used, ok := c.pkg.TypesInfo().Uses[key]; ok {
					if usedVar, ok := used.(*types.Var); ok {
						addedFields[usedVar] = true
					}
				}
			}
		}
	}

	// Add struct fields.
	if t, ok := types.Unalias(clInfo.clType).(*types.Struct); ok {
		const deltaScore = 0.0001
		for i := range t.NumFields() {
			field := t.Field(i)
			if !addedFields[field] {
				c.deepState.enqueue(candidate{
					obj:   field,
					score: highScore - float64(i)*deltaScore,
				})
			}
		}

		// Fall through and add lexical completions if we aren't
		// certain we are in the key part of a key-value pair.
		if !clInfo.maybeInFieldName {
			return nil
		}
	}

	return c.lexical(ctx)
}

// enclosingCompositeLiteral returns information about the composite literal enclosing the
// position.
// It returns nil on failure; for example, if there is no type information for a
// node on path.
func enclosingCompositeLiteral(path []ast.Node, pos token.Pos, info *types.Info) *compLitInfo {
	for _, n := range path {
		switch n := n.(type) {
		case *ast.CompositeLit:
			// The enclosing node will be a composite literal if the user has just
			// opened the curly brace (e.g. &x{<>) or the completion request is triggered
			// from an already completed composite literal expression (e.g. &x{foo: 1, <>})
			//
			// The position is not part of the composite literal unless it falls within the
			// curly braces (e.g. "foo.Foo<>Struct{}").
			if !(n.Lbrace < pos && pos <= n.Rbrace) {
				// Keep searching since we may yet be inside a composite literal.
				// For example "Foo{B: Ba<>{}}".
				break
			}

			tv, ok := info.Types[n]
			if !ok {
				return nil
			}

			clInfo := compLitInfo{
				cl:     n,
				clType: typesinternal.Unpointer(tv.Type).Underlying(),
			}

			var (
				expr    ast.Expr
				hasKeys bool
			)
			for _, el := range n.Elts {
				// Remember the expression that the position falls in, if any.
				if el.Pos() <= pos && pos <= el.End() {
					expr = el
				}

				if kv, ok := el.(*ast.KeyValueExpr); ok {
					hasKeys = true
					// If expr == el then we know the position falls in this expression,
					// so also record kv as the enclosing *ast.KeyValueExpr.
					if expr == el {
						clInfo.kv = kv
						break
					}
				}
			}

			if clInfo.kv != nil {
				// If in a *ast.KeyValueExpr, we know we are in the key if the position
				// is to the left of the colon (e.g. "Foo{F<>: V}".
				clInfo.inKey = pos <= clInfo.kv.Colon
			} else if hasKeys {
				// If we aren't in a *ast.KeyValueExpr but the composite literal has
				// other *ast.KeyValueExprs, we must be on the key side of a new
				// *ast.KeyValueExpr (e.g. "Foo{F: V, <>}").
				clInfo.inKey = true
			} else {
				switch clInfo.clType.(type) {
				case *types.Struct:
					if len(n.Elts) == 0 {
						// If the struct literal is empty, next could be a struct field
						// name or an expression (e.g. "Foo{<>}" could become "Foo{F:}"
						// or "Foo{someVar}").
						clInfo.maybeInFieldName = true
					} else if len(n.Elts) == 1 {
						// If there is one expression and the position is in that expression
						// and the expression is an identifier, we may be writing a field
						// name or an expression (e.g. "Foo{F<>}").
						_, clInfo.maybeInFieldName = expr.(*ast.Ident)
					}
				case *types.Map:
					// If we aren't in a *ast.KeyValueExpr we must be adding a new key
					// to the map.
					clInfo.inKey = true
				}
			}

			return &clInfo
		default:
			if breaksExpectedTypeInference(n, pos) {
				return nil
			}
		}
	}

	return nil
}

// enclosingFunction returns the signature and body of the function
// enclosing the given position.
func enclosingFunction(path []ast.Node, info *types.Info) *funcInfo {
	for _, node := range path {
		switch t := node.(type) {
		case *ast.FuncDecl:
			if obj, ok := info.Defs[t.Name]; ok {
				return &funcInfo{
					sig:  obj.Type().(*types.Signature),
					body: t.Body,
				}
			}
		case *ast.FuncLit:
			if typ, ok := info.Types[t]; ok {
				if sig, _ := typ.Type.(*types.Signature); sig == nil {
					// golang/go#49397: it should not be possible, but we somehow arrived
					// here with a non-signature type, most likely due to AST mangling
					// such that node.Type is not a FuncType.
					return nil
				}
				return &funcInfo{
					sig:  typ.Type.(*types.Signature),
					body: t.Body,
				}
			}
		}
	}
	return nil
}

func expectedCompositeLiteralType(clInfo *compLitInfo, pos token.Pos) types.Type {
	switch t := clInfo.clType.(type) {
	case *types.Slice:
		if clInfo.inKey {
			return types.Typ[types.UntypedInt]
		}
		return t.Elem()
	case *types.Array:
		if clInfo.inKey {
			return types.Typ[types.UntypedInt]
		}
		return t.Elem()
	case *types.Map:
		if clInfo.inKey {
			return t.Key()
		}
		return t.Elem()
	case *types.Struct:
		// If we are completing a key (i.e. field name), there is no expected type.
		if clInfo.inKey {
			return nil
		}

		// If we are in a key-value pair, but not in the key, then we must be on the
		// value side. The expected type of the value will be determined from the key.
		if clInfo.kv != nil {
			if key, ok := clInfo.kv.Key.(*ast.Ident); ok {
				for field := range t.Fields() {
					if field.Name() == key.Name {
						return field.Type()
					}
				}
			}
		} else {
			// If we aren't in a key-value pair and aren't in the key, we must be using
			// implicit field names.

			// The order of the literal fields must match the order in the struct definition.
			// Find the element that the position belongs to and suggest that field's type.
			if i := exprAtPos(pos, clInfo.cl.Elts); i < t.NumFields() {
				return t.Field(i).Type()
			}
		}
	}
	return nil
}

// typeMod represents an operator that changes the expected type.
type typeMod struct {
	mod      typeModKind
	arrayLen int64
}

type typeModKind int

const (
	dereference   typeModKind = iota // pointer indirection: "*"
	reference                        // adds level of pointer: "&" for values, "*" for type names
	chanRead                         // channel read operator: "<-"
	sliceType                        // make a slice type: "[]" in "[]int"
	arrayType                        // make an array type: "[2]" in "[2]int"
	invoke                           // make a function call: "()" in "foo()"
	takeSlice                        // take slice of array: "[:]" in "foo[:]"
	takeDotDotDot                    // turn slice into variadic args: "..." in "foo..."
	index                            // index into slice/array: "[0]" in "foo[0]"
)

type objKind int

const (
	kindAny   objKind = 0
	kindArray objKind = 1 << iota
	kindSlice
	kindChan
	kindMap
	kindStruct
	kindString
	kindInt
	kindBool
	kindBytes
	kindPtr
	kindInterface
	kindFloat
	kindComplex
	kindError
	kindStringer
	kindFunc
	kindRange0Func
	kindRange1Func
	kindRange2Func
)

// penalizedObj represents an object that should be disfavored as a
// completion candidate.
type penalizedObj struct {
	// objChain is the full "chain", e.g. "foo.bar().baz" becomes
	// []types.Object{foo, bar, baz}.
	objChain []types.Object
	// penalty is score penalty in the range (0, 1).
	penalty float64
}

// candidateInference holds information we have inferred about a type that can be
// used at the current position.
type candidateInference struct {
	// objType is the desired type of an object used at the query position.
	objType types.Type

	// objKind is a mask of expected kinds of types such as "map", "slice", etc.
	objKind objKind

	// variadic is true if we are completing the initial variadic
	// parameter. For example:
	//   append([]T{}, <>)      // objType=T variadic=true
	//   append([]T{}, T{}, <>) // objType=T variadic=false
	variadic bool

	// modifiers are prefixes such as "*", "&" or "<-" that influence how
	// a candidate type relates to the expected type.
	modifiers []typeMod

	// convertibleTo is a type our candidate type must be convertible to.
	convertibleTo types.Type

	// needsExactType is true if the candidate type must be exactly the type of
	// the objType, e.g. an interface rather than it's implementors.
	//
	// This is necessary when objType is derived using reverse type inference:
	// any different (but assignable) type may lead to different type inference,
	// which may no longer be valid.
	//
	// For example, consider the following scenario:
	//
	//   func f[T any](x T) []T { return []T{x} }
	//
	//   var s []any = f(_)
	//
	// Reverse type inference would infer that the type at _ must be 'any', but
	// that does not mean that any object in the lexical scope is valid: the type of
	// the object must be *exactly* any, otherwise type inference will cause the
	// slice assignment to fail.
	needsExactType bool

	// typeName holds information about the expected type name at
	// position, if any.
	typeName typeNameInference

	// assignees are the types that would receive a function call's
	// results at the position. For example:
	//
	// foo := 123
	// foo, bar := <>
	//
	// at "<>", the assignees are [int, <invalid>].
	assignees []types.Type

	// variadicAssignees is true if we could be completing an inner
	// function call that fills out an outer function call's variadic
	// params. For example:
	//
	// func foo(int, ...string) {}
	//
	// foo(<>)         // variadicAssignees=true
	// foo(bar<>)      // variadicAssignees=true
	// foo(bar, baz<>) // variadicAssignees=false
	variadicAssignees bool

	// penalized holds expressions that should be disfavored as
	// candidates. For example, it tracks expressions already used in a
	// switch statement's other cases. Each expression is tracked using
	// its entire object "chain" allowing differentiation between
	// "a.foo" and "b.foo" when "a" and "b" are the same type.
	penalized []penalizedObj

	// objChain contains the chain of objects representing the
	// surrounding *ast.SelectorExpr. For example, if we are completing
	// "foo.bar.ba<>", objChain will contain []types.Object{foo, bar}.
	objChain []types.Object
}

// typeNameInference holds information about the expected type name at
// position.
type typeNameInference struct {
	// wantTypeName is true if we expect the name of a type.
	wantTypeName bool

	// modifiers are prefixes such as "*", "&" or "<-" that influence how
	// a candidate type relates to the expected type.
	modifiers []typeMod

	// assertableFrom is a type that must be assertable to our candidate type.
	assertableFrom types.Type

	// wantComparable is true if we want a comparable type.
	wantComparable bool

	// seenTypeSwitchCases tracks types that have already been used by
	// the containing type switch.
	seenTypeSwitchCases []types.Type

	// compLitType is true if we are completing a composite literal type
	// name, e.g "foo<>{}".
	compLitType bool

	// isTypeParam is true if we are completing a type instantiation parameter
	isTypeParam bool
}

// expectedCandidate returns information about the expected candidate
// for an expression at the query position.
func expectedCandidate(ctx context.Context, c *completer) (inf candidateInference) {
	inf.typeName = expectTypeName(c)

	if c.enclosingCompositeLiteral != nil {
		inf.objType = expectedCompositeLiteralType(c.enclosingCompositeLiteral, c.pos)
	}

Nodes:
	for i, node := range c.path {
		switch node := node.(type) {
		case *ast.BinaryExpr:
			// Determine if query position comes from left or right of op.
			e := node.X
			if c.pos < node.OpPos {
				e = node.Y
			}
			if tv, ok := c.pkg.TypesInfo().Types[e]; ok {
				switch node.Op {
				case token.LAND, token.LOR:
					// Don't infer "bool" type for "&&" or "||". Often you want
					// to compose a boolean expression from non-boolean
					// candidates.
				default:
					inf.objType = tv.Type
				}
				break Nodes
			}
		case *ast.AssignStmt:
			objType, assignees := expectedAssignStmtTypes(c.pkg, node, c.pos)
			inf.objType = objType
			inf.assignees = assignees
			return inf
		case *ast.ValueSpec:
			inf.objType = expectedValueSpecType(c.pkg, node, c.pos)
			return
		case *ast.ReturnStmt:
			if c.enclosingFunc != nil {
				inf.objType = expectedReturnStmtType(c.enclosingFunc.sig, node, c.pos)
			}
			return inf
		case *ast.SendStmt:
			if typ := expectedSendStmtType(c.pkg, node, c.pos); typ != nil {
				inf.objType = typ
			}
			return inf
		case *ast.CallExpr:
			// Only consider CallExpr args if position falls between parens.
			if node.Lparen < c.pos && c.pos <= node.Rparen {
				// For type conversions like "int64(foo)" we can only infer our
				// desired type is convertible to int64.
				if typ := typeConversion(node, c.pkg.TypesInfo()); typ != nil {
					inf.convertibleTo = typ
					break Nodes
				}

				if sig, ok := c.pkg.TypesInfo().Types[node.Fun].Type.(*types.Signature); ok {
					// Out of bounds arguments get no inference completion.
					if !sig.Variadic() && exprAtPos(c.pos, node.Args) >= sig.Params().Len() {
						return inf
					}

					// Inference is necessary only when function results are generic.
					var free typeparams.Free
					if free.Has(sig.Results()) {
						targs := c.getTypeArgs(node)
						res := inferExpectedResultTypes(c, i)
						substs := reverseInferTypeArgs(sig, targs, res)
						inst := instantiate(sig, substs)
						if inst != nil {
							// TODO(jacobz): If partial signature instantiation becomes possible,
							// make needsExactType only true if necessary.
							// Currently, ambiguous cases always resolve to a conversion expression
							// wrapping the completion, which is occasionally superfluous.
							inf.needsExactType = true
							sig = inst
						}
					}

					inf = c.expectedCallParamType(inf, node, sig)
				}

				if funIdent, ok := node.Fun.(*ast.Ident); ok {
					obj := c.pkg.TypesInfo().ObjectOf(funIdent)

					if obj != nil && obj.Parent() == types.Universe {
						// Defer call to builtinArgType so we can provide it the
						// inferred type from its parent node.
						defer func() {
							inf = c.builtinArgType(obj, node, inf)
							inf.objKind = c.builtinArgKind(ctx, obj, node)
						}()

						// The expected type of builtin arguments like append() is
						// the expected type of the builtin call itself. For
						// example:
						//
						// var foo []int = append(<>)
						//
						// To find the expected type at <> we "skip" the append()
						// node and get the expected type one level up, which is
						// []int.
						continue Nodes
					}
				}

				return inf
			}
		case *ast.CaseClause:
			if swtch, ok := findSwitchStmt(c.path[i+1:], c.pos, node).(*ast.SwitchStmt); ok {
				if tv, ok := c.pkg.TypesInfo().Types[swtch.Tag]; ok {
					inf.objType = tv.Type

					// Record which objects have already been used in the case
					// statements so we don't suggest them again.
					for _, cc := range swtch.Body.List {
						for _, caseExpr := range cc.(*ast.CaseClause).List {
							// Don't record the expression we are currently completing.
							if caseExpr.Pos() < c.pos && c.pos <= caseExpr.End() {
								continue
							}

							if objs := objChain(c.pkg.TypesInfo(), caseExpr); len(objs) > 0 {
								inf.penalized = append(inf.penalized, penalizedObj{objChain: objs, penalty: 0.1})
							}
						}
					}
				}
			}
			return inf
		case *ast.SliceExpr:
			// Make sure position falls within the brackets (e.g. "foo[a:<>]").
			if node.Lbrack < c.pos && c.pos <= node.Rbrack {
				inf.objType = types.Typ[types.UntypedInt]
			}
			return inf
		case *ast.IndexExpr:
			// Make sure position falls within the brackets (e.g. "foo[<>]").
			if node.Lbrack < c.pos && c.pos <= node.Rbrack {
				if tv, ok := c.pkg.TypesInfo().Types[node.X]; ok {
					switch t := tv.Type.Underlying().(type) {
					case *types.Map:
						inf.objType = t.Key()
					case *types.Slice, *types.Array:
						inf.objType = types.Typ[types.UntypedInt]
					}

					if ct := expectedConstraint(tv.Type, 0); ct != nil {
						inf.objType = ct
						inf.typeName.wantTypeName = true
						inf.typeName.isTypeParam = true
						if typ := c.inferExpectedTypeArg(i+1, 0); typ != nil {
							inf.objType = typ
						}
					}
				}
			}
			return inf
		case *ast.IndexListExpr:
			if node.Lbrack < c.pos && c.pos <= node.Rbrack {
				if tv, ok := c.pkg.TypesInfo().Types[node.X]; ok {
					typeParamIdx := exprAtPos(c.pos, node.Indices)
					if ct := expectedConstraint(tv.Type, typeParamIdx); ct != nil {
						inf.objType = ct
						inf.typeName.wantTypeName = true
						inf.typeName.isTypeParam = true
						if typ := c.inferExpectedTypeArg(i+1, typeParamIdx); typ != nil {
							inf.objType = typ
						}
					}
				}
			}
			return inf
		case *ast.RangeStmt:
			if astutil.NodeContainsPos(node.X, c.pos) {
				inf.objKind |= kindSlice | kindArray | kindMap | kindString
				if node.Key == nil && node.Value == nil {
					inf.objKind |= kindRange0Func | kindRange1Func | kindRange2Func
				} else if node.Value == nil {
					inf.objKind |= kindChan | kindRange1Func | kindRange2Func
				} else {
					inf.objKind |= kindRange2Func
				}
			}
			return inf
		case *ast.StarExpr:
			inf.modifiers = append(inf.modifiers, typeMod{mod: dereference})
		case *ast.UnaryExpr:
			switch node.Op {
			case token.AND:
				inf.modifiers = append(inf.modifiers, typeMod{mod: reference})
			case token.ARROW:
				inf.modifiers = append(inf.modifiers, typeMod{mod: chanRead})
			}
		case *ast.DeferStmt, *ast.GoStmt:
			inf.objKind |= kindFunc
			return inf
		default:
			if breaksExpectedTypeInference(node, c.pos) {
				return inf
			}
		}
	}

	return inf
}

// inferExpectedResultTypes takes the index of a call expression within the completion
// path and uses its surroundings to infer the expected result tuple of the call's signature.
// Returns the signature result tuple as a slice, or nil if reverse type inference fails.
//
// # For example
//
// func generic[T any, U any](a T, b U) (T, U) { ... }
//
// var x TypeA
// var y TypeB
// x, y := generic(<cursor>, <cursor>)
//
// inferExpectedResultTypes can determine that the expected result type of the function is (TypeA, TypeB)
func inferExpectedResultTypes(c *completer, callNodeIdx int) []types.Type {
	callNode, ok := c.path[callNodeIdx].(*ast.CallExpr)
	if !ok {
		bug.Reportf("inferExpectedResultTypes given callNodeIndex: %v which is not a ast.CallExpr\n", callNodeIdx)
		return nil
	}

	if len(c.path) <= callNodeIdx+1 {
		return nil
	}

	var expectedResults []types.Type

	// Check the parents of the call node to extract the expected result types of the call signature.
	// Currently reverse inferences are only supported with the following parent expressions,
	// however this list isn't exhaustive.
	switch node := c.path[callNodeIdx+1].(type) {
	case *ast.KeyValueExpr:
		enclosingCompositeLiteral := enclosingCompositeLiteral(c.path[callNodeIdx:], callNode.Pos(), c.pkg.TypesInfo())
		if enclosingCompositeLiteral != nil && !wantStructFieldCompletions(enclosingCompositeLiteral) {
			expectedResults = append(expectedResults, expectedCompositeLiteralType(enclosingCompositeLiteral, callNode.Pos()))
		}
	case *ast.AssignStmt:
		objType, assignees := expectedAssignStmtTypes(c.pkg, node, c.pos)
		if len(assignees) > 0 {
			return assignees
		} else if objType != nil {
			expectedResults = append(expectedResults, objType)
		}
	case *ast.ValueSpec:
		if resultType := expectedValueSpecType(c.pkg, node, c.pos); resultType != nil {
			expectedResults = append(expectedResults, resultType)
		}
	case *ast.SendStmt:
		if resultType := expectedSendStmtType(c.pkg, node, c.pos); resultType != nil {
			expectedResults = append(expectedResults, resultType)
		}
	case *ast.ReturnStmt:
		if c.enclosingFunc == nil {
			return nil
		}

		// As a special case for reverse call inference in
		//
		// return foo(<cursor>)
		//
		// Pull the result type from the enclosing function
		if exprAtPos(c.pos, node.Results) == 0 {
			if callSig := c.pkg.TypesInfo().Types[callNode.Fun].Type.(*types.Signature); callSig != nil {
				enclosingResults := c.enclosingFunc.sig.Results()
				if callSig.Results().Len() == enclosingResults.Len() {
					expectedResults = make([]types.Type, enclosingResults.Len())
					for i := range enclosingResults.Len() {
						expectedResults[i] = enclosingResults.At(i).Type()
					}
					return expectedResults
				}
			}
		}

		if resultType := expectedReturnStmtType(c.enclosingFunc.sig, node, c.pos); resultType != nil {
			expectedResults = append(expectedResults, resultType)
		}
	case *ast.CallExpr:
		// TODO(jacobz): This is a difficult case because the normal CallExpr candidateInference
		// leans on control flow which is inaccessible in this helper function.
		// It would probably take a significant refactor to a recursive solution to make this case
		// work cleanly. For now it's unimplemented.
	}
	return expectedResults
}

// expectedSendStmtType return the expected type at the position.
// Returns nil if unknown.
func expectedSendStmtType(pkg *cache.Package, node *ast.SendStmt, pos token.Pos) types.Type {
	// Make sure we are on right side of arrow (e.g. "foo <- <>").
	if pos > node.Arrow+1 {
		if tv, ok := pkg.TypesInfo().Types[node.Chan]; ok {
			if ch, ok := tv.Type.Underlying().(*types.Chan); ok {
				return ch.Elem()
			}
		}
	}
	return nil
}

// expectedValueSpecType returns the expected type of a ValueSpec at the query
// position.
func expectedValueSpecType(pkg *cache.Package, node *ast.ValueSpec, pos token.Pos) types.Type {
	if node.Type != nil && pos > node.Type.End() {
		return pkg.TypesInfo().TypeOf(node.Type)
	}
	return nil
}

// expectedAssignStmtTypes analyzes the provided assignStmt, and checks
// to see if the provided pos is within a RHS expression. If so, it report
// the expected type of that expression, and the LHS type(s) to which it
// is being assigned.
func expectedAssignStmtTypes(pkg *cache.Package, node *ast.AssignStmt, pos token.Pos) (objType types.Type, assignees []types.Type) {
	// Only rank completions if you are on the right side of the token.
	if pos > node.TokPos {
		i := exprAtPos(pos, node.Rhs)
		if i >= len(node.Lhs) {
			i = len(node.Lhs) - 1
		}
		if tv, ok := pkg.TypesInfo().Types[node.Lhs[i]]; ok {
			objType = tv.Type
		}

		// If we have a single expression on the RHS, record the LHS
		// assignees so we can favor multi-return function calls with
		// matching result values.
		if len(node.Rhs) <= 1 {
			for _, lhs := range node.Lhs {
				assignees = append(assignees, pkg.TypesInfo().TypeOf(lhs))
			}
		} else {
			// Otherwise, record our single assignee, even if its type is
			// not available. We use this info to downrank functions
			// with the wrong number of result values.
			assignees = append(assignees, pkg.TypesInfo().TypeOf(node.Lhs[i]))
		}
	}
	return objType, assignees
}

// expectedReturnStmtType returns the expected type of a return statement.
// Returns nil if enclosingSig is nil.
func expectedReturnStmtType(enclosingSig *types.Signature, node *ast.ReturnStmt, pos token.Pos) types.Type {
	if enclosingSig != nil {
		if resultIdx := exprAtPos(pos, node.Results); resultIdx < enclosingSig.Results().Len() {
			return enclosingSig.Results().At(resultIdx).Type()
		}
	}
	return nil
}

// Returns the number of type arguments in a callExpr
func (c *completer) getTypeArgs(callExpr *ast.CallExpr) []types.Type {
	var targs []types.Type
	switch fun := callExpr.Fun.(type) {
	case *ast.IndexListExpr:
		for i := range fun.Indices {
			if typ, ok := c.pkg.TypesInfo().Types[fun.Indices[i]]; ok && typeIsValid(typ.Type) {
				targs = append(targs, typ.Type)
			}
		}
	case *ast.IndexExpr:
		if typ, ok := c.pkg.TypesInfo().Types[fun.Index]; ok && typeIsValid(typ.Type) {
			targs = []types.Type{typ.Type}
		}
	}
	return targs
}

// reverseInferTypeArgs takes a generic signature, a list of passed type arguments, and the expected concrete return types
// inferred from the signature's call site. If possible, it returns a list of types that could be used as the type arguments
// to the signature. If not possible, it returns nil.
//
// Does not panic if any of the arguments are nil.
func reverseInferTypeArgs(sig *types.Signature, typeArgs []types.Type, expectedResults []types.Type) []types.Type {
	if len(expectedResults) == 0 || sig == nil || sig.TypeParams().Len() == 0 || sig.Results().Len() != len(expectedResults) {
		return nil
	}

	tparams := make([]*types.TypeParam, sig.TypeParams().Len())
	for i := range sig.TypeParams().Len() {
		tparams[i] = sig.TypeParams().At(i)
	}

	for i := len(typeArgs); i < sig.TypeParams().Len(); i++ {
		typeArgs = append(typeArgs, nil)
	}

	u := newUnifier(tparams, typeArgs)
	for i, assignee := range expectedResults {
		// Unify does not check the constraints of the type parameters.
		// Checks must be applied after.
		if !u.unify(sig.Results().At(i).Type(), assignee, unifyModeExact) {
			return nil
		}
	}

	substs := make([]types.Type, sig.TypeParams().Len())
	for i := range sig.TypeParams().Len() {
		if sub := u.handles[sig.TypeParams().At(i)]; sub != nil && *sub != nil {
			// Ensure the inferred subst is assignable to the type parameter's constraint.
			if !assignableTo(*sub, sig.TypeParams().At(i).Constraint()) {
				return nil
			}
			substs[i] = *sub
		}
	}
	return substs
}

// inferExpectedTypeArg gives a type param candidateInference based on the surroundings of its call site.
// If successful, the inf parameter is returned with only it's objType field updated.
//
// callNodeIdx is the index within the completion path of the type parameter's parent call expression.
// typeParamIdx is the index of the type parameter at the completion pos.
func (c *completer) inferExpectedTypeArg(callNodeIdx int, typeParamIdx int) types.Type {
	if len(c.path) <= callNodeIdx {
		return nil
	}

	callNode, ok := c.path[callNodeIdx].(*ast.CallExpr)
	if !ok {
		return nil
	}
	sig, ok := c.pkg.TypesInfo().Types[callNode.Fun].Type.(*types.Signature)
	if !ok {
		return nil
	}

	// Infer the type parameters in a function call based on context
	expectedResults := inferExpectedResultTypes(c, callNodeIdx)
	if typeParamIdx < 0 || typeParamIdx >= sig.TypeParams().Len() {
		return nil
	}
	substs := reverseInferTypeArgs(sig, nil, expectedResults)
	if substs == nil || substs[typeParamIdx] == nil {
		return nil
	}

	return substs[typeParamIdx]
}

// Instantiates a signature with a set of type parameters.
// Wrapper around types.Instantiate but bad arguments won't cause a panic.
func instantiate(sig *types.Signature, substs []types.Type) *types.Signature {
	if substs == nil || sig == nil || len(substs) != sig.TypeParams().Len() {
		return nil
	}

	for i := range substs {
		if substs[i] == nil {
			substs[i] = sig.TypeParams().At(i)
		}
	}

	if inst, err := types.Instantiate(nil, sig, substs, true); err == nil {
		if inst, ok := inst.(*types.Signature); ok {
			return inst
		}
	}

	return nil
}

func (c *completer) expectedCallParamType(inf candidateInference, node *ast.CallExpr, sig *types.Signature) candidateInference {
	numParams := sig.Params().Len()
	if numParams == 0 {
		return inf
	}

	exprIdx := exprAtPos(c.pos, node.Args)

	// If we have one or zero arg expressions, we may be
	// completing to a function call that returns multiple
	// values, in turn getting passed in to the surrounding
	// call. Record the assignees so we can favor function
	// calls that return matching values.
	if len(node.Args) <= 1 && exprIdx == 0 {
		for v := range sig.Params().Variables() {
			inf.assignees = append(inf.assignees, v.Type())
		}

		// Record that we may be completing into variadic parameters.
		inf.variadicAssignees = sig.Variadic()
	}

	// Make sure not to run past the end of expected parameters.
	if exprIdx >= numParams {
		inf.objType = sig.Params().At(numParams - 1).Type()
	} else {
		inf.objType = sig.Params().At(exprIdx).Type()
	}

	if sig.Variadic() && exprIdx >= (numParams-1) {
		// If we are completing a variadic param, deslice the variadic type.
		inf.objType = deslice(inf.objType)
		// Record whether we are completing the initial variadic param.
		inf.variadic = exprIdx == numParams-1 && len(node.Args) <= numParams

		// Check if we can infer object kind from printf verb.
		inf.objKind |= printfArgKind(c.pkg.TypesInfo(), node, exprIdx)
	}

	// If our expected type is an uninstantiated generic type param,
	// swap to the constraint which will do a decent job filtering
	// candidates.
	if tp, _ := inf.objType.(*types.TypeParam); tp != nil {
		inf.objType = tp.Constraint()
	}

	return inf
}

func expectedConstraint(t types.Type, idx int) types.Type {
	var tp *types.TypeParamList
	if pnt, ok := t.(typesinternal.NamedOrAlias); ok {
		tp = pnt.TypeParams()
	} else if sig, _ := t.Underlying().(*types.Signature); sig != nil {
		tp = sig.TypeParams()
	}
	if tp == nil || idx >= tp.Len() {
		return nil
	}
	return tp.At(idx).Constraint()
}

// objChain decomposes e into a chain of objects if possible. For
// example, "foo.bar().baz" will yield []types.Object{foo, bar, baz}.
// If any part can't be turned into an object, return nil.
func objChain(info *types.Info, e ast.Expr) []types.Object {
	var objs []types.Object

	for e != nil {
		switch n := e.(type) {
		case *ast.Ident:
			obj := info.ObjectOf(n)
			if obj == nil {
				return nil
			}
			objs = append(objs, obj)
			e = nil
		case *ast.SelectorExpr:
			obj := info.ObjectOf(n.Sel)
			if obj == nil {
				return nil
			}
			objs = append(objs, obj)
			e = n.X
		case *ast.CallExpr:
			if len(n.Args) > 0 {
				return nil
			}
			e = n.Fun
		default:
			return nil
		}
	}

	// Reverse order so the layout matches the syntactic order.
	slices.Reverse(objs)

	return objs
}

// applyTypeModifiers applies the list of type modifiers to a type.
// It returns nil if the modifiers could not be applied.
func (ci candidateInference) applyTypeModifiers(typ types.Type, addressable bool) types.Type {
	for _, mod := range ci.modifiers {
		switch mod.mod {
		case dereference:
			// For every "*" indirection operator, remove a pointer layer
			// from candidate type.
			if ptr, ok := typ.Underlying().(*types.Pointer); ok {
				typ = ptr.Elem()
			} else {
				return nil
			}
		case reference:
			// For every "&" address operator, add another pointer layer to
			// candidate type, if the candidate is addressable.
			if addressable {
				typ = types.NewPointer(typ)
			} else {
				return nil
			}
		case chanRead:
			// For every "<-" operator, remove a layer of channelness.
			if ch, ok := typ.(*types.Chan); ok {
				typ = ch.Elem()
			} else {
				return nil
			}
		}
	}

	return typ
}

// applyTypeNameModifiers applies the list of type modifiers to a type name.
func (ci candidateInference) applyTypeNameModifiers(typ types.Type) types.Type {
	for _, mod := range ci.typeName.modifiers {
		switch mod.mod {
		case reference:
			typ = types.NewPointer(typ)
		case arrayType:
			typ = types.NewArray(typ, mod.arrayLen)
		case sliceType:
			typ = types.NewSlice(typ)
		}
	}
	return typ
}

// matchesVariadic returns true if we are completing a variadic
// parameter and candType is a compatible slice type.
func (ci candidateInference) matchesVariadic(candType types.Type) bool {
	return ci.variadic && ci.objType != nil && assignableTo(candType, types.NewSlice(ci.objType))
}

// findSwitchStmt returns an *ast.CaseClause's corresponding *ast.SwitchStmt or
// *ast.TypeSwitchStmt. path should start from the case clause's first ancestor.
func findSwitchStmt(path []ast.Node, pos token.Pos, c *ast.CaseClause) ast.Stmt {
	// Make sure position falls within a "case <>:" clause.
	if exprAtPos(pos, c.List) >= len(c.List) {
		return nil
	}
	// A case clause is always nested within a block statement in a switch statement.
	if len(path) < 2 {
		return nil
	}
	if _, ok := path[0].(*ast.BlockStmt); !ok {
		return nil
	}
	switch s := path[1].(type) {
	case *ast.SwitchStmt:
		return s
	case *ast.TypeSwitchStmt:
		return s
	default:
		return nil
	}
}

// breaksExpectedTypeInference reports if an expression node's type is unrelated
// to its child expression node types. For example, "Foo{Bar: x.Baz(<>)}" should
// expect a function argument, not a composite literal value.
func breaksExpectedTypeInference(n ast.Node, pos token.Pos) bool {
	switch n := n.(type) {
	case *ast.CompositeLit:
		// Doesn't break inference if pos is in type name.
		// For example: "Foo<>{Bar: 123}"
		return n.Type == nil || !astutil.NodeContainsPos(n.Type, pos)
	case *ast.CallExpr:
		// Doesn't break inference if pos is in func name.
		// For example: "Foo<>(123)"
		return !astutil.NodeContainsPos(n.Fun, pos)
	case *ast.FuncLit, *ast.IndexExpr, *ast.SliceExpr:
		return true
	default:
		return false
	}
}

// expectTypeName returns information about the expected type name at position.
func expectTypeName(c *completer) typeNameInference {
	var inf typeNameInference

Nodes:
	for i, p := range c.path {
		switch n := p.(type) {
		case *ast.FieldList:
			// Expect a type name if pos is in a FieldList. This applies to
			// FuncType params/results, FuncDecl receiver, StructType, and
			// InterfaceType. We don't need to worry about the field name
			// because completion bails out early if pos is in an *ast.Ident
			// that defines an object.
			inf.wantTypeName = true
			break Nodes
		case *ast.CaseClause:
			// Expect type names in type switch case clauses.
			if swtch, ok := findSwitchStmt(c.path[i+1:], c.pos, n).(*ast.TypeSwitchStmt); ok {
				// The case clause types must be assertable from the type switch parameter.
				ast.Inspect(swtch.Assign, func(n ast.Node) bool {
					if ta, ok := n.(*ast.TypeAssertExpr); ok {
						inf.assertableFrom = c.pkg.TypesInfo().TypeOf(ta.X)
						return false
					}
					return true
				})
				inf.wantTypeName = true

				// Track the types that have already been used in this
				// switch's case statements so we don't recommend them.
				for _, e := range swtch.Body.List {
					for _, typeExpr := range e.(*ast.CaseClause).List {
						// Skip if type expression contains pos. We don't want to
						// count it as already used if the user is completing it.
						if typeExpr.Pos() < c.pos && c.pos <= typeExpr.End() {
							continue
						}

						if t := c.pkg.TypesInfo().TypeOf(typeExpr); t != nil {
							inf.seenTypeSwitchCases = append(inf.seenTypeSwitchCases, t)
						}
					}
				}

				break Nodes
			}
			return typeNameInference{}
		case *ast.TypeAssertExpr:
			// Expect type names in type assert expressions.
			if n.Lparen < c.pos && c.pos <= n.Rparen {
				// The type in parens must be assertable from the expression type.
				inf.assertableFrom = c.pkg.TypesInfo().TypeOf(n.X)
				inf.wantTypeName = true
				break Nodes
			}
			return typeNameInference{}
		case *ast.StarExpr:
			inf.modifiers = append(inf.modifiers, typeMod{mod: reference})
		case *ast.CompositeLit:
			// We want a type name if position is in the "Type" part of a
			// composite literal (e.g. "Foo<>{}").
			if n.Type != nil && n.Type.Pos() <= c.pos && c.pos <= n.Type.End() {
				inf.wantTypeName = true
				inf.compLitType = true

				if i < len(c.path)-1 {
					// Track preceding "&" operator. Technically it applies to
					// the composite literal and not the type name, but if
					// affects our type completion nonetheless.
					if u, ok := c.path[i+1].(*ast.UnaryExpr); ok && u.Op == token.AND {
						inf.modifiers = append(inf.modifiers, typeMod{mod: reference})
					}
				}
			}
			break Nodes
		case *ast.ArrayType:
			// If we are inside the "Elt" part of an array type, we want a type name.
			if n.Elt.Pos() <= c.pos && c.pos <= n.Elt.End() {
				inf.wantTypeName = true
				if n.Len == nil {
					// No "Len" expression means a slice type.
					inf.modifiers = append(inf.modifiers, typeMod{mod: sliceType})
				} else {
					// Try to get the array type using the constant value of "Len".
					tv, ok := c.pkg.TypesInfo().Types[n.Len]
					if ok && tv.Value != nil && tv.Value.Kind() == constant.Int {
						if arrayLen, ok := constant.Int64Val(tv.Value); ok {
							inf.modifiers = append(inf.modifiers, typeMod{mod: arrayType, arrayLen: arrayLen})
						}
					}
				}

				// ArrayTypes can be nested, so keep going if our parent is an
				// ArrayType.
				if i < len(c.path)-1 {
					if _, ok := c.path[i+1].(*ast.ArrayType); ok {
						continue Nodes
					}
				}

				break Nodes
			}
		case *ast.MapType:
			inf.wantTypeName = true
			if n.Key != nil {
				inf.wantComparable = astutil.NodeContainsPos(n.Key, c.pos)
			} else {
				// If the key is empty, assume we are completing the key if
				// pos is directly after the "map[".
				inf.wantComparable = c.pos == n.Pos()+token.Pos(len("map["))
			}
			break Nodes
		case *ast.ValueSpec:
			inf.wantTypeName = n.Type != nil && astutil.NodeContainsPos(n.Type, c.pos)
			break Nodes
		case *ast.TypeSpec:
			inf.wantTypeName = astutil.NodeContainsPos(n.Type, c.pos)
		default:
			if breaksExpectedTypeInference(p, c.pos) {
				return typeNameInference{}
			}
		}
	}

	return inf
}

func (c *completer) fakeObj(T types.Type) *types.Var {
	return types.NewVar(token.NoPos, c.pkg.Types(), "", T)
}

// derivableTypes iterates types you can derive from t. For example,
// from "foo" we might derive "&foo", and "foo()".
func derivableTypes(t types.Type, addressable bool, f func(t types.Type, addressable bool, mod typeModKind) bool) bool {
	switch t := t.Underlying().(type) {
	case *types.Signature:
		// If t is a func type with a single result, offer the result type.
		if t.Results().Len() == 1 && f(t.Results().At(0).Type(), false, invoke) {
			return true
		}
	case *types.Array:
		if f(t.Elem(), true, index) {
			return true
		}
		// Try converting array to slice.
		if f(types.NewSlice(t.Elem()), false, takeSlice) {
			return true
		}
	case *types.Pointer:
		if f(t.Elem(), false, dereference) {
			return true
		}
	case *types.Slice:
		if f(t.Elem(), true, index) {
			return true
		}
	case *types.Map:
		if f(t.Elem(), false, index) {
			return true
		}
	case *types.Chan:
		if f(t.Elem(), false, chanRead) {
			return true
		}
	}

	// Check if c is addressable and a pointer to c matches our type inference.
	if addressable && f(types.NewPointer(t), false, reference) {
		return true
	}

	return false
}

// anyCandType reports whether f returns true for any candidate type
// derivable from c. It searches up to three levels of type
// modification. For example, given "foo" we could discover "***foo"
// or "*foo()".
func (c *candidate) anyCandType(f func(t types.Type, addressable bool) bool) bool {
	if c.obj == nil || c.obj.Type() == nil {
		return false
	}

	const maxDepth = 3

	var searchTypes func(t types.Type, addressable bool, mods []typeModKind) bool
	searchTypes = func(t types.Type, addressable bool, mods []typeModKind) bool {
		if f(t, addressable) {
			if len(mods) > 0 {
				newMods := make([]typeModKind, len(mods)+len(c.mods))
				copy(newMods, mods)
				copy(newMods[len(mods):], c.mods)
				c.mods = newMods
			}
			return true
		}

		if len(mods) == maxDepth {
			return false
		}

		return derivableTypes(t, addressable, func(t types.Type, addressable bool, mod typeModKind) bool {
			return searchTypes(t, addressable, append(mods, mod))
		})
	}

	return searchTypes(c.obj.Type(), c.addressable, make([]typeModKind, 0, maxDepth))
}

// matchingCandidate reports whether cand matches our type inferences.
// It mutates cand's score in certain cases.
func (c *completer) matchingCandidate(cand *candidate) bool {
	if c.completionContext.commentCompletion {
		return false
	}

	// Bail out early if we are completing a field name in a composite literal.
	if v, ok := cand.obj.(*types.Var); ok && v.IsField() && wantStructFieldCompletions(c.enclosingCompositeLiteral) {
		return true
	}

	if isTypeName(cand.obj) {
		return c.matchingTypeName(cand)
	} else if c.wantTypeName() {
		// If we want a type, a non-type object never matches.
		return false
	}

	if c.inference.candTypeMatches(cand) {
		return true
	}

	candType := cand.obj.Type()
	if candType == nil {
		return false
	}

	if sig, ok := candType.Underlying().(*types.Signature); ok {
		if c.inference.assigneesMatch(cand, sig) {
			// Invoke the candidate if its results are multi-assignable.
			cand.mods = append(cand.mods, invoke)
			return true
		}
	}

	// Default to invoking *types.Func candidates. This is so function
	// completions in an empty statement (or other cases with no expected type)
	// are invoked by default.
	if isFunc(cand.obj) {
		cand.mods = append(cand.mods, invoke)
	}

	return false
}

// candTypeMatches reports whether cand makes a good completion
// candidate given the candidate inference. cand's score may be
// mutated to downrank the candidate in certain situations.
func (ci *candidateInference) candTypeMatches(cand *candidate) bool {
	var (
		expTypes     = make([]types.Type, 0, 2)
		variadicType types.Type
	)
	if ci.objType != nil {
		expTypes = append(expTypes, ci.objType)

		if ci.variadic {
			variadicType = types.NewSlice(ci.objType)
			expTypes = append(expTypes, variadicType)
		}
	}

	return cand.anyCandType(func(candType types.Type, addressable bool) bool {
		// Take into account any type modifiers on the expected type.
		candType = ci.applyTypeModifiers(candType, addressable)
		if candType == nil {
			return false
		}

		if ci.convertibleTo != nil && convertibleTo(candType, ci.convertibleTo) {
			return true
		}

		for _, expType := range expTypes {
			if isEmptyInterface(expType) {
				// If any type matches the expected type, fall back to other
				// considerations below.
				//
				// TODO(rfindley): can this be expressed via scoring, rather than a boolean?
				// Why is it the case that we break ties for the empty interface, but
				// not for other expected types that may be satisfied by a lot of
				// types, such as fmt.Stringer?
				continue
			}

			matches := ci.typeMatches(expType, candType)
			if !matches {
				// If candType doesn't otherwise match, consider if we can
				// convert candType directly to expType.
				if considerTypeConversion(candType, expType, cand.path) {
					cand.convertTo = expType
					// Give a major score penalty so we always prefer directly
					// assignable candidates, all else equal.
					cand.score *= 0.5
					return true
				}

				continue
			}

			if expType == variadicType {
				cand.mods = append(cand.mods, takeDotDotDot)
			}

			// Candidate matches, but isn't exactly identical to the expected type.
			// Apply a conversion to allow it to match.
			if ci.needsExactType && !types.Identical(candType, expType) {
				cand.convertTo = expType
				// Ranks barely lower if it needs a conversion, even though it's perfectly valid.
				cand.score *= 0.95
			}

			// Lower candidate score for untyped conversions. This avoids
			// ranking untyped constants above candidates with an exact type
			// match. Don't lower score of builtin constants, e.g. "true".
			if isUntyped(candType) && !types.Identical(candType, expType) && cand.obj.Parent() != types.Universe {
				// Bigger penalty for deep completions into other packages to
				// avoid random constants from other packages popping up all
				// the time.
				if len(cand.path) > 0 && isPkgName(cand.path[0]) {
					cand.score *= 0.5
				} else {
					cand.score *= 0.75
				}
			}

			return true
		}

		// If we don't have a specific expected type, fall back to coarser
		// object kind checks.
		if ci.objType == nil || isEmptyInterface(ci.objType) {
			// If we were able to apply type modifiers to our candidate type,
			// count that as a match. For example:
			//
			//   var foo chan int
			//   <-fo<>
			//
			// We were able to apply the "<-" type modifier to "foo", so "foo"
			// matches.
			if len(ci.modifiers) > 0 {
				return true
			}

			// If we didn't have an exact type match, check if our object kind
			// matches.
			if ci.kindMatches(candType) {
				if ci.objKind == kindFunc {
					cand.mods = append(cand.mods, invoke)
				}
				return true
			}
		}

		return false
	})
}

// considerTypeConversion returns true if we should offer a completion
// automatically converting "from" to "to".
func considerTypeConversion(from, to types.Type, path []types.Object) bool {
	// Don't offer to convert deep completions from other packages.
	// Otherwise there are many random package level consts/vars that
	// pop up as candidates all the time.
	if len(path) > 0 && isPkgName(path[0]) {
		return false
	}

	if _, ok := from.(*types.TypeParam); ok {
		return false
	}

	if !convertibleTo(from, to) {
		return false
	}

	// Don't offer to convert ints to strings since that probably
	// doesn't do what the user wants.
	if isBasicKind(from, types.IsInteger) && isBasicKind(to, types.IsString) {
		return false
	}

	return true
}

// typeMatches reports whether an object of candType makes a good
// completion candidate given the expected type expType.
func (ci *candidateInference) typeMatches(expType, candType types.Type) bool {
	// Handle untyped values specially since AssignableTo gives false negatives
	// for them (see https://golang.org/issue/32146).
	if candBasic, ok := candType.Underlying().(*types.Basic); ok {
		if expBasic, ok := expType.Underlying().(*types.Basic); ok {
			// Note that the candidate and/or the expected can be untyped.
			// In "fo<> == 100" the expected type is untyped, and the
			// candidate could also be an untyped constant.

			// Sort by is_untyped and then by is_int to simplify below logic.
			a, b := candBasic.Info(), expBasic.Info()
			if a&types.IsUntyped == 0 || (b&types.IsInteger > 0 && b&types.IsUntyped > 0) {
				a, b = b, a
			}

			// If at least one is untyped...
			if a&types.IsUntyped > 0 {
				switch {
				// Untyped integers are compatible with floats.
				case a&types.IsInteger > 0 && b&types.IsFloat > 0:
					return true

				// Check if their constant kind (bool|int|float|complex|string) matches.
				// This doesn't take into account the constant value, so there will be some
				// false positives due to integer sign and overflow.
				case a&types.IsConstType == b&types.IsConstType:
					return true
				}
			}
		}
	}

	// AssignableTo covers the case where the types are equal, but also handles
	// cases like assigning a concrete type to an interface type.
	return assignableTo(candType, expType)
}

// kindMatches reports whether candType's kind matches our expected
// kind (e.g. slice, map, etc.).
func (ci *candidateInference) kindMatches(candType types.Type) bool {
	return ci.objKind > 0 && ci.objKind&candKind(candType) > 0
}

// assigneesMatch reports whether an invocation of sig matches the
// number and type of any assignees.
func (ci *candidateInference) assigneesMatch(cand *candidate, sig *types.Signature) bool {
	if len(ci.assignees) == 0 {
		return false
	}

	// Uniresult functions are always usable and are handled by the
	// normal, non-assignees type matching logic.
	if sig.Results().Len() == 1 {
		return false
	}

	// Don't prefer completing into func(...interface{}) calls since all
	// functions would match.
	if ci.variadicAssignees && len(ci.assignees) == 1 && isEmptyInterface(deslice(ci.assignees[0])) {
		return false
	}

	var numberOfResultsCouldMatch bool
	if ci.variadicAssignees {
		numberOfResultsCouldMatch = sig.Results().Len() >= len(ci.assignees)-1
	} else {
		numberOfResultsCouldMatch = sig.Results().Len() == len(ci.assignees)
	}

	// If our signature doesn't return the right number of values, it's
	// not a match, so downrank it. For example:
	//
	//  var foo func() (int, int)
	//  a, b, c := <> // downrank "foo()" since it only returns two values
	if !numberOfResultsCouldMatch {
		cand.score /= 2
		return false
	}

	// If at least one assignee has a valid type, and all valid
	// assignees match the corresponding sig result value, the signature
	// is a match.
	allMatch := false
	for i := range sig.Results().Len() {
		var assignee types.Type

		// If we are completing into variadic parameters, deslice the
		// expected variadic type.
		if ci.variadicAssignees && i >= len(ci.assignees)-1 {
			assignee = ci.assignees[len(ci.assignees)-1]
			if elem := deslice(assignee); elem != nil {
				assignee = elem
			}
		} else {
			assignee = ci.assignees[i]
		}

		if assignee == nil || assignee == types.Typ[types.Invalid] {
			continue
		}

		allMatch = ci.typeMatches(assignee, sig.Results().At(i).Type())
		if !allMatch {
			break
		}
	}
	return allMatch
}

func (c *completer) matchingTypeName(cand *candidate) bool {
	if !c.wantTypeName() {
		return false
	}

	wantExactTypeParam := c.inference.typeName.isTypeParam &&
		c.inference.typeName.wantTypeName && c.inference.needsExactType

	typeMatches := func(candType types.Type) bool {
		// Take into account any type name modifier prefixes.
		candType = c.inference.applyTypeNameModifiers(candType)

		if from := c.inference.typeName.assertableFrom; from != nil {
			// Don't suggest the starting type in type assertions. For example,
			// if "foo" is an io.Writer, don't suggest "foo.(io.Writer)".
			if types.Identical(from, candType) {
				return false
			}

			if intf, ok := from.Underlying().(*types.Interface); ok {
				if !types.AssertableTo(intf, candType) {
					return false
				}
			}
		}

		// Suggest the exact type when performing reverse type inference.
		// x = Foo[<>]()
		// Where x is an interface kind, only suggest the interface type rather than its implementors
		if wantExactTypeParam && types.Identical(candType, c.inference.objType) {
			return true
		}

		if c.inference.typeName.wantComparable && !types.Comparable(candType) {
			return false
		}

		// Skip this type if it has already been used in another type
		// switch case.
		for _, seen := range c.inference.typeName.seenTypeSwitchCases {
			if types.Identical(candType, seen) {
				return false
			}
		}

		// We can expect a type name and have an expected type in cases like:
		//
		//   var foo []int
		//   foo = []i<>
		//
		// Where our expected type is "[]int", and we expect a type name.
		if c.inference.objType != nil {
			return assignableTo(candType, c.inference.objType)
		}

		// Default to saying any type name is a match.
		return true
	}

	t := cand.obj.Type()

	if typeMatches(t) {
		return true
	}

	if !types.IsInterface(t) && typeMatches(types.NewPointer(t)) {
		if c.inference.typeName.compLitType {
			// If we are completing a composite literal type as in
			// "foo<>{}", to make a pointer we must prepend "&".
			cand.mods = append(cand.mods, reference)
		} else {
			// If we are completing a normal type name such as "foo<>", to
			// make a pointer we must prepend "*".
			cand.mods = append(cand.mods, dereference)
		}
		return true
	}

	return false
}

var (
	// "interface { Error() string }" (i.e. error)
	errorIntf = types.Universe.Lookup("error").Type().Underlying().(*types.Interface)

	// "interface { String() string }" (i.e. fmt.Stringer)
	stringerIntf = types.NewInterfaceType([]*types.Func{
		types.NewFunc(token.NoPos, nil, "String", types.NewSignatureType(
			nil, nil,
			nil, nil,
			types.NewTuple(types.NewParam(token.NoPos, nil, "", types.Typ[types.String])),
			false,
		)),
	}, nil).Complete()

	byteType = types.Universe.Lookup("byte").Type()

	boolType = types.Universe.Lookup("bool").Type()
)

// candKind returns the objKind of candType, if any.
func candKind(candType types.Type) objKind {
	var kind objKind

	switch t := candType.Underlying().(type) {
	case *types.Array:
		kind |= kindArray
		if t.Elem() == byteType {
			kind |= kindBytes
		}
	case *types.Slice:
		kind |= kindSlice
		if t.Elem() == byteType {
			kind |= kindBytes
		}
	case *types.Chan:
		kind |= kindChan
	case *types.Map:
		kind |= kindMap
	case *types.Pointer:
		kind |= kindPtr

		// Some builtins handle array pointers as arrays, so just report a pointer
		// to an array as an array.
		if _, isArray := t.Elem().Underlying().(*types.Array); isArray {
			kind |= kindArray
		}
	case *types.Interface:
		kind |= kindInterface
	case *types.Basic:
		switch info := t.Info(); {
		case info&types.IsString > 0:
			kind |= kindString
		case info&types.IsInteger > 0:
			kind |= kindInt
		case info&types.IsFloat > 0:
			kind |= kindFloat
		case info&types.IsComplex > 0:
			kind |= kindComplex
		case info&types.IsBoolean > 0:
			kind |= kindBool
		}
	case *types.Signature:
		kind |= kindFunc

		switch rangeFuncParamCount(t) {
		case 0:
			kind |= kindRange0Func
		case 1:
			kind |= kindRange1Func
		case 2:
			kind |= kindRange2Func
		}
	}

	if types.Implements(candType, errorIntf) {
		kind |= kindError
	}

	if types.Implements(candType, stringerIntf) {
		kind |= kindStringer
	}

	return kind
}

// If sig looks like a range func, return param count, else return -1.
func rangeFuncParamCount(sig *types.Signature) int {
	if sig.Results().Len() != 0 || sig.Params().Len() != 1 {
		return -1
	}

	yieldSig, _ := sig.Params().At(0).Type().Underlying().(*types.Signature)
	if yieldSig == nil {
		return -1
	}

	if yieldSig.Results().Len() != 1 || yieldSig.Results().At(0).Type() != boolType {
		return -1
	}

	return yieldSig.Params().Len()
}

// innermostScope returns the innermost scope for c.pos.
func (c *completer) innermostScope() *types.Scope {
	for _, s := range c.scopes {
		if s != nil {
			return s
		}
	}
	return nil
}

// isSlice reports whether the object's underlying type is a slice.
func isSlice(obj types.Object) bool {
	if obj != nil && obj.Type() != nil {
		if _, ok := obj.Type().Underlying().(*types.Slice); ok {
			return true
		}
	}
	return false
}

// forEachPackageMember calls f(tok, id, fn) for each package-level
// TYPE/VAR/CONST/FUNC declaration in the Go source file, based on a
// quick partial parse. fn is non-nil only for function declarations.
// The AST position information is garbage.
func forEachPackageMember(content []byte, f func(tok token.Token, id *ast.Ident, fn *ast.FuncDecl)) {
	purged := astutil.PurgeFuncBodies(content)
	file, _ := parser.ParseFile(token.NewFileSet(), "", purged, parser.SkipObjectResolution)
	for _, decl := range file.Decls {
		switch decl := decl.(type) {
		case *ast.GenDecl:
			for _, spec := range decl.Specs {
				switch spec := spec.(type) {
				case *ast.ValueSpec: // var/const
					for _, id := range spec.Names {
						f(decl.Tok, id, nil)
					}
				case *ast.TypeSpec:
					f(decl.Tok, spec.Name, nil)
				}
			}
		case *ast.FuncDecl:
			if decl.Recv == nil {
				f(token.FUNC, decl.Name, decl)
			}
		}
	}
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}


================================================
FILE: gopls/internal/golang/completion/deep_completion.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"context"
	"go/types"
	"strings"
	"time"

	"golang.org/x/tools/gopls/internal/util/typesutil"
	"golang.org/x/tools/internal/packagepath"
)

// MaxDeepCompletions limits deep completion results because in most cases
// there are too many to be useful.
const MaxDeepCompletions = 3

// deepCompletionState stores our state as we search for deep completions.
// "deep completion" refers to searching into objects' fields and methods to
// find more completion candidates.
type deepCompletionState struct {
	// enabled indicates whether deep completion is permitted.
	enabled bool

	// queueClosed is used to disable adding new sub-fields to search queue
	// once we're running out of our time budget.
	queueClosed bool

	// thisQueue holds the current breadth first search queue.
	thisQueue []candidate

	// nextQueue holds the next breadth first search iteration's queue.
	nextQueue []candidate

	// highScores tracks the highest deep candidate scores we have found
	// so far. This is used to avoid work for low scoring deep candidates.
	highScores [MaxDeepCompletions]float64

	// candidateCount is the count of unique deep candidates encountered
	// so far.
	candidateCount int
}

// enqueue adds a candidate to the search queue.
func (s *deepCompletionState) enqueue(cand candidate) {
	s.nextQueue = append(s.nextQueue, cand)
}

// scorePenalty computes a deep candidate score penalty. A candidate is
// penalized based on depth to favor shallower candidates. We also give a
// slight bonus to unexported objects and a slight additional penalty to
// function objects.
func (s *deepCompletionState) scorePenalty(cand *candidate) float64 {
	var deepPenalty float64
	for _, dc := range cand.path {
		deepPenalty++

		if !dc.Exported() {
			deepPenalty -= 0.1
		}

		if _, isSig := dc.Type().Underlying().(*types.Signature); isSig {
			deepPenalty += 0.1
		}
	}

	// Normalize penalty to a max depth of 10.
	return deepPenalty / 10
}

// isHighScore returns whether score is among the top MaxDeepCompletions deep
// candidate scores encountered so far. If so, it adds score to highScores,
// possibly displacing an existing high score.
func (s *deepCompletionState) isHighScore(score float64) bool {
	// Invariant: s.highScores is sorted with highest score first. Unclaimed
	// positions are trailing zeros.

	// If we beat an existing score then take its spot.
	for i, deepScore := range s.highScores {
		if score <= deepScore {
			continue
		}

		if deepScore != 0 && i != len(s.highScores)-1 {
			// If this wasn't an empty slot then we need to scooch everyone
			// down one spot.
			copy(s.highScores[i+1:], s.highScores[i:])
		}
		s.highScores[i] = score
		return true
	}

	return false
}

// newPath returns path from search root for an object following a given
// candidate.
func (s *deepCompletionState) newPath(cand candidate, obj types.Object) []types.Object {
	path := make([]types.Object, len(cand.path)+1)
	copy(path, cand.path)
	path[len(path)-1] = obj

	return path
}

// deepSearch searches a candidate and its subordinate objects for completion
// items if deep completion is enabled and adds the valid candidates to
// completion items.
func (c *completer) deepSearch(ctx context.Context, minDepth int, deadline *time.Time) {
	defer func() {
		// We can return early before completing the search, so be sure to
		// clear out our queues to not impact any further invocations.
		c.deepState.thisQueue = c.deepState.thisQueue[:0]
		c.deepState.nextQueue = c.deepState.nextQueue[:0]
	}()

	depth := 0 // current depth being processed
	// Stop reports whether we should stop the search immediately.
	stop := func() bool {
		// Context cancellation indicates that the actual completion operation was
		// cancelled, so ignore minDepth and deadline.
		select {
		case <-ctx.Done():
			return true
		default:
		}
		// Otherwise, only stop if we've searched at least minDepth and reached the deadline.
		return depth > minDepth && deadline != nil && time.Now().After(*deadline)
	}

	for len(c.deepState.nextQueue) > 0 {
		depth++
		if stop() {
			return
		}
		c.deepState.thisQueue, c.deepState.nextQueue = c.deepState.nextQueue, c.deepState.thisQueue[:0]

	outer:
		for _, cand := range c.deepState.thisQueue {
			obj := cand.obj

			if obj == nil {
				continue
			}

			// At the top level, dedupe by object.
			if len(cand.path) == 0 {
				if c.seen[obj] {
					continue
				}
				c.seen[obj] = true
			}

			// If obj is not accessible because it lives in another package and is
			// not exported, don't treat it as a completion candidate unless it's
			// a package completion candidate.
			if !c.completionContext.packageCompletion &&
				obj.Pkg() != nil && obj.Pkg() != c.pkg.Types() && !obj.Exported() {
				continue
			}

			if cand.imp != nil && !packagepath.CanImport(string(c.pkg.Metadata().PkgPath), cand.imp.importPath) {
				continue // inaccessible internal package
			}

			// If we want a type name, don't offer non-type name candidates.
			// However, do offer package names since they can contain type names,
			// and do offer any candidate without a type since we aren't sure if it
			// is a type name or not (i.e. unimported candidate).
			if c.wantTypeName() && obj.Type() != nil && !isTypeName(obj) && !isPkgName(obj) {
				continue
			}

			// When searching deep, make sure we don't have a cycle in our chain.
			// We don't dedupe by object because we want to allow both "foo.Baz"
			// and "bar.Baz" even though "Baz" is represented the same types.Object
			// in both.
			for _, seenObj := range cand.path {
				if seenObj == obj {
					continue outer
				}
			}

			c.addCandidate(ctx, &cand)

			c.deepState.candidateCount++
			if c.opts.budget > 0 && c.deepState.candidateCount%100 == 0 {
				if stop() {
					return
				}
				spent := float64(time.Since(c.startTime)) / float64(c.opts.budget)
				// If we are almost out of budgeted time, no further elements
				// should be added to the queue. This ensures remaining time is
				// used for processing current queue.
				if !c.deepState.queueClosed && spent >= 0.85 {
					c.deepState.queueClosed = true
				}
			}

			// if deep search is disabled, don't add any more candidates.
			if !c.deepState.enabled || c.deepState.queueClosed {
				continue
			}

			// Searching members for a type name doesn't make sense.
			if isTypeName(obj) {
				continue
			}
			if obj.Type() == nil {
				continue
			}

			// Don't search embedded fields because they were already included in their
			// parent's fields.
			if v, ok := obj.(*types.Var); ok && v.Embedded() {
				continue
			}

			if sig, ok := obj.Type().Underlying().(*types.Signature); ok {
				// If obj is a function that takes no arguments and returns one
				// value, keep searching across the function call.
				if sig.Params().Len() == 0 && sig.Results().Len() == 1 {
					path := c.deepState.newPath(cand, obj)
					// The result of a function call is not addressable.
					c.methodsAndFields(sig.Results().At(0).Type(), false, cand.imp, func(newCand candidate) {
						newCand.pathInvokeMask = cand.pathInvokeMask | (1 << uint64(len(cand.path)))
						newCand.path = path
						c.deepState.enqueue(newCand)
					})
				}
			}

			path := c.deepState.newPath(cand, obj)
			switch obj := obj.(type) {
			case *types.PkgName:
				c.packageMembers(obj.Imported(), stdScore, cand.imp, func(newCand candidate) {
					newCand.pathInvokeMask = cand.pathInvokeMask
					newCand.path = path
					c.deepState.enqueue(newCand)
				})
			default:
				c.methodsAndFields(obj.Type(), cand.addressable, cand.imp, func(newCand candidate) {
					newCand.pathInvokeMask = cand.pathInvokeMask
					newCand.path = path
					c.deepState.enqueue(newCand)
				})
			}
		}
	}
}

// addCandidate adds a completion candidate to suggestions, without searching
// its members for more candidates.
func (c *completer) addCandidate(ctx context.Context, cand *candidate) {
	obj := cand.obj
	if c.matchingCandidate(cand) {
		cand.score *= highScore

		if p := c.penalty(cand); p > 0 {
			cand.score *= (1 - p)
		}
	} else if isTypeName(obj) {
		// If obj is a *types.TypeName that didn't otherwise match, check
		// if a literal object of this type makes a good candidate.

		// We only care about named types (i.e. don't want builtin types).
		if _, isNamed := obj.Type().(*types.Named); isNamed {
			c.literal(ctx, obj.Type(), cand.imp)
		}
	}

	// Lower score of method calls so we prefer fields and vars over calls.
	if cand.hasMod(invoke) {
		if sig, ok := obj.Type().Underlying().(*types.Signature); ok && sig.Recv() != nil {
			cand.score *= 0.9
		}
	}

	// Prefer private objects over public ones.
	if !obj.Exported() && obj.Parent() != types.Universe {
		cand.score *= 1.1
	}

	// Slight penalty for index modifier (e.g. changing "foo" to
	// "foo[]") to curb false positives.
	if cand.hasMod(index) {
		cand.score *= 0.9
	}

	// Favor shallow matches by lowering score according to depth.
	cand.score -= cand.score * c.deepState.scorePenalty(cand)

	if cand.score < 0 {
		cand.score = 0
	}

	cand.name = deepCandName(cand)
	if item, err := c.item(ctx, *cand); err == nil {
		c.items = append(c.items, item)
	}
}

// deepCandName produces the full candidate name including any
// ancestor objects. For example, "foo.bar().baz" for candidate "baz".
func deepCandName(cand *candidate) string {
	totalLen := len(cand.obj.Name())
	for i, obj := range cand.path {
		totalLen += len(obj.Name()) + 1
		if cand.pathInvokeMask&(1<<uint16(i)) > 0 {
			totalLen += 2
		}
	}

	var buf strings.Builder
	buf.Grow(totalLen)

	for i, obj := range cand.path {
		buf.WriteString(obj.Name())
		if fn, ok := obj.(*types.Func); ok {
			buf.WriteString(typesutil.FormatTypeParams(fn.Signature().TypeParams()))
		}
		if cand.pathInvokeMask&(1<<uint16(i)) > 0 {
			buf.WriteByte('(')
			buf.WriteByte(')')
		}
		buf.WriteByte('.')
	}

	buf.WriteString(cand.obj.Name())

	return buf.String()
}

// penalty reports a score penalty for cand in the range (0, 1).
// For example, a candidate is penalized if it has already been used
// in another switch case statement.
func (c *completer) penalty(cand *candidate) float64 {
	for _, p := range c.inference.penalized {
		if c.objChainMatches(cand, p.objChain) {
			return p.penalty
		}
	}

	return 0
}

// objChainMatches reports whether cand combined with the surrounding
// object prefix matches chain.
func (c *completer) objChainMatches(cand *candidate, chain []types.Object) bool {
	// For example, when completing:
	//
	//   foo.ba<>
	//
	// If we are considering the deep candidate "bar.baz", cand is baz,
	// objChain is [foo] and deepChain is [bar]. We would match the
	// chain [foo, bar, baz].
	if len(chain) != len(c.inference.objChain)+len(cand.path)+1 {
		return false
	}

	if chain[len(chain)-1] != cand.obj {
		return false
	}

	for i, o := range c.inference.objChain {
		if chain[i] != o {
			return false
		}
	}

	for i, o := range cand.path {
		if chain[i+len(c.inference.objChain)] != o {
			return false
		}
	}

	return true
}


================================================
FILE: gopls/internal/golang/completion/deep_completion_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"testing"
)

func TestDeepCompletionIsHighScore(t *testing.T) {
	// Test that deepCompletionState.isHighScore properly tracks the top
	// N=MaxDeepCompletions scores.

	var s deepCompletionState

	if !s.isHighScore(1) {
		// No other scores yet, anything is a winner.
		t.Error("1 should be high score")
	}

	// Fill up with higher scores.
	for range MaxDeepCompletions {
		if !s.isHighScore(10) {
			t.Error("10 should be high score")
		}
	}

	// High scores should be filled with 10s so 2 is not a high score.
	if s.isHighScore(2) {
		t.Error("2 shouldn't be high score")
	}
}


================================================
FILE: gopls/internal/golang/completion/definition.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"
	"go/types"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
)

// some function definitions in test files can be completed
// So far, TestFoo(t *testing.T), TestMain(m *testing.M)
// BenchmarkFoo(b *testing.B), FuzzFoo(f *testing.F)

// path[0] is known to be *ast.Ident
func definition(path []ast.Node, obj types.Object, pgf *parsego.File) ([]CompletionItem, *Selection) {
	if _, ok := obj.(*types.Func); !ok {
		return nil, nil // not a function at all
	}
	if !strings.HasSuffix(pgf.URI.Path(), "_test.go") {
		return nil, nil // not a test file
	}

	name := path[0].(*ast.Ident).Name
	if len(name) == 0 {
		// can't happen
		return nil, nil
	}
	start := path[0].Pos()
	end := path[0].End()
	sel := &Selection{
		content: "", // why isn't this name?
		cursor:  start,
		tokFile: pgf.Tok,
		start:   start,
		end:     end,
		mapper:  pgf.Mapper,
	}
	sel.check()
	var ans []CompletionItem
	var hasParens bool
	n, ok := path[1].(*ast.FuncDecl)
	if !ok {
		return nil, nil // can't happen
	}
	if n.Recv != nil {
		return nil, nil // a method, not a function
	}
	t := n.Type.Params
	if t.Closing != t.Opening {
		hasParens = true
	}

	// Always suggest TestMain, if possible
	if strings.HasPrefix("TestMain", name) {
		if hasParens {
			ans = append(ans, defItem("TestMain", obj))
		} else {
			ans = append(ans, defItem("TestMain(m *testing.M)", obj))
		}
	}

	// If a snippet is possible, suggest it
	if strings.HasPrefix("Test", name) {
		if hasParens {
			ans = append(ans, defItem("Test", obj))
		} else {
			ans = append(ans, defSnippet("Test", "(t *testing.T)", obj))
		}
		return ans, sel
	} else if strings.HasPrefix("Benchmark", name) {
		if hasParens {
			ans = append(ans, defItem("Benchmark", obj))
		} else {
			ans = append(ans, defSnippet("Benchmark", "(b *testing.B)", obj))
		}
		return ans, sel
	} else if strings.HasPrefix("Fuzz", name) {
		if hasParens {
			ans = append(ans, defItem("Fuzz", obj))
		} else {
			ans = append(ans, defSnippet("Fuzz", "(f *testing.F)", obj))
		}
		return ans, sel
	}

	// Fill in the argument for what the user has already typed
	if got := defMatches(name, "Test", path, "(t *testing.T)"); got != "" {
		ans = append(ans, defItem(got, obj))
	} else if got := defMatches(name, "Benchmark", path, "(b *testing.B)"); got != "" {
		ans = append(ans, defItem(got, obj))
	} else if got := defMatches(name, "Fuzz", path, "(f *testing.F)"); got != "" {
		ans = append(ans, defItem(got, obj))
	}
	return ans, sel
}

// defMatches returns text for defItem, never for defSnippet
func defMatches(name, pat string, path []ast.Node, arg string) string {
	if !strings.HasPrefix(name, pat) {
		return ""
	}
	c, _ := utf8.DecodeRuneInString(name[len(pat):])
	if unicode.IsLower(c) {
		return ""
	}
	fd, ok := path[1].(*ast.FuncDecl)
	if !ok {
		// we don't know what's going on
		return ""
	}
	fp := fd.Type.Params
	if len(fp.List) > 0 {
		// signature already there, nothing to suggest
		return ""
	}
	if fp.Opening != fp.Closing {
		// nothing: completion works on words, not easy to insert arg
		return ""
	}
	// suggesting signature too
	return name + arg
}

func defSnippet(prefix, suffix string, obj types.Object) CompletionItem {
	var sn snippet.Builder
	sn.WriteText(prefix)
	sn.WritePlaceholder(func(b *snippet.Builder) { b.WriteText("Xxx") })
	sn.WriteText(suffix + " {\n\t")
	sn.WriteFinalTabstop()
	sn.WriteText("\n}")
	return CompletionItem{
		Label:         prefix + "Xxx" + suffix,
		Detail:        "tab, type the rest of the name, then tab",
		Kind:          protocol.FunctionCompletion,
		Depth:         0,
		Score:         10,
		snippet:       &sn,
		Documentation: prefix + " test function",
		isSlice:       isSlice(obj),
	}
}
func defItem(val string, obj types.Object) CompletionItem {
	return CompletionItem{
		Label:         val,
		InsertText:    val,
		Kind:          protocol.FunctionCompletion,
		Depth:         0,
		Score:         9, // prefer the snippets when available
		Documentation: "complete the function name",
		isSlice:       isSlice(obj),
	}
}


================================================
FILE: gopls/internal/golang/completion/format.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/doc"
	"go/types"
	"strings"

	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/typesutil"
	internalastutil "golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
)

var (
	errNoMatch  = errors.New("not a surrounding match")
	errLowScore = errors.New("not a high scoring candidate")
)

// item formats a candidate to a CompletionItem.
func (c *completer) item(ctx context.Context, cand candidate) (CompletionItem, error) {
	obj := cand.obj

	// if the object isn't a valid match against the surrounding, return early.
	matchScore := c.matcher.Score(cand.name)
	if matchScore <= 0 {
		return CompletionItem{}, errNoMatch
	}
	cand.score *= float64(matchScore)

	// Ignore deep candidates that won't be in the MaxDeepCompletions anyway.
	if len(cand.path) != 0 && !c.deepState.isHighScore(cand.score) {
		return CompletionItem{}, errLowScore
	}

	// Handle builtin types separately.
	if obj.Parent() == types.Universe {
		return c.formatBuiltin(ctx, cand)
	}

	var (
		label         = cand.name
		detail        = types.TypeString(obj.Type(), c.qual)
		insert        = label
		kind          = protocol.TextCompletion
		snip          snippet.Builder
		protocolEdits []protocol.TextEdit
	)
	if obj.Type() == nil {
		detail = ""
	}

	type hasTypeParams interface{ TypeParams() *types.TypeParamList }
	if genericType, _ := obj.Type().(hasTypeParams); genericType != nil && isTypeName(obj) && c.wantTypeParams() {
		// golang/go#71044: note that type names can be basic types, even in
		// receiver position, for invalid code.
		tparams := genericType.TypeParams()
		label += typesutil.FormatTypeParams(tparams)
		insert = label // maintain invariant above (label == insert)
	}

	snip.WriteText(insert)

	switch obj := obj.(type) {
	case *types.TypeName:
		detail, kind = golang.FormatType(obj.Type(), c.qual)
	case *types.Const:
		kind = protocol.ConstantCompletion
	case *types.Var:
		if _, ok := obj.Type().(*types.Struct); ok {
			detail = "struct{...}" // for anonymous unaliased struct types
		} else if obj.IsField() {
			var err error
			detail, err = golang.FormatVarType(ctx, c.snapshot, c.pkg, obj, c.qual, c.mq)
			if err != nil {
				return CompletionItem{}, err
			}
		}
		if obj.IsField() {
			kind = protocol.FieldCompletion
			c.structFieldSnippet(cand, detail, &snip)
		} else {
			kind = protocol.VariableCompletion
		}
		if obj.Type() == nil {
			break
		}
	case *types.Func:
		if obj.Signature().Recv() == nil {
			kind = protocol.FunctionCompletion
		} else {
			kind = protocol.MethodCompletion
		}
	case *types.PkgName:
		kind = protocol.ModuleCompletion
		detail = fmt.Sprintf("%q", obj.Imported().Path())
	case *types.Label:
		kind = protocol.ConstantCompletion
		detail = "label"
	}

	var prefix string
	for _, mod := range cand.mods {
		switch mod {
		case reference:
			prefix = "&" + prefix
		case dereference:
			prefix = "*" + prefix
		case chanRead:
			prefix = "<-" + prefix
		}
	}

	var (
		suffix   string
		funcType = obj.Type()
	)
Suffixes:
	for _, mod := range cand.mods {
		switch mod {
		case invoke:
			if sig, ok := funcType.Underlying().(*types.Signature); ok {
				s, err := golang.NewSignature(ctx, c.snapshot, c.pkg, sig, nil, c.qual, c.mq)
				if err != nil {
					return CompletionItem{}, err
				}

				tparams := s.TypeParams()
				if len(tparams) > 0 {
					// Eliminate the suffix of type parameters that are
					// likely redundant because they can probably be
					// inferred from the argument types (#51783).
					//
					// We don't bother doing the reverse inference from
					// result types as result-only type parameters are
					// quite unusual.
					free := inferableTypeParams(sig)
					for i := sig.TypeParams().Len() - 1; i >= 0; i-- {
						tparam := sig.TypeParams().At(i)
						if !free[tparam] {
							break
						}
						tparams = tparams[:i] // eliminate
					}
				}

				c.functionCallSnippet("", tparams, s.Params(), &snip)
				if sig.Results().Len() == 1 {
					funcType = sig.Results().At(0).Type()
				}
				detail = "func" + s.Format()
			}

			if !c.opts.snippets {
				// Without snippets the candidate will not include "()". Don't
				// add further suffixes since they will be invalid. For
				// example, with snippets "foo()..." would become "foo..."
				// without snippets if we added the dotDotDot.
				break Suffixes
			}
		case takeSlice:
			suffix += "[:]"
		case takeDotDotDot:
			suffix += "..."
		case index:
			snip.WriteText("[")
			snip.WritePlaceholder(nil)
			snip.WriteText("]")
		}
	}

	// If this candidate needs an additional import statement,
	// add the additional text edits needed.
	if cand.imp != nil {
		addlEdits, err := c.importEdits(cand.imp)

		if err != nil {
			return CompletionItem{}, err
		}

		protocolEdits = append(protocolEdits, addlEdits...)
		if kind != protocol.ModuleCompletion {
			if detail != "" {
				detail += " "
			}
			detail += fmt.Sprintf("(from %q)", cand.imp.importPath)
		}
	}

	if cand.convertTo != nil {
		conv := c.formatConversion(cand.convertTo)
		prefix = conv.prefix + prefix
		suffix = conv.suffix
	}

	if prefix != "" {
		// If we are in a selector, add an edit to place prefix before selector.
		if sel := enclosingSelector(c.path, c.pos); sel != nil {
			edits, err := c.editText(sel.Pos(), sel.Pos(), prefix)
			if err != nil {
				return CompletionItem{}, err
			}
			protocolEdits = append(protocolEdits, edits...)
		} else {
			// If there is no selector, just stick the prefix at the start.
			insert = prefix + insert
			snip.PrependText(prefix)
		}
	}

	if suffix != "" {
		insert += suffix
		snip.WriteText(suffix)
	}

	detail = strings.TrimPrefix(detail, "untyped ")
	// override computed detail with provided detail, if something is provided.
	if cand.detail != "" {
		detail = cand.detail
	}
	item := CompletionItem{
		Label:               label,
		InsertText:          insert,
		AdditionalTextEdits: protocolEdits,
		Detail:              detail,
		Kind:                kind,
		Score:               cand.score,
		Depth:               len(cand.path),
		snippet:             &snip,
		isSlice:             isSlice(obj),
	}
	// If the user doesn't want documentation for completion items.
	if !c.opts.documentation {
		return item, nil
	}
	pos := safetoken.StartPosition(c.pkg.FileSet(), obj.Pos())

	// We ignore errors here, because some types, like "unsafe" or "error",
	// may not have valid positions that we can use to get documentation.
	if !pos.IsValid() {
		return item, nil
	}

	comment, err := golang.HoverDocForObject(ctx, c.snapshot, c.pkg.FileSet(), obj)
	if err != nil {
		event.Error(ctx, fmt.Sprintf("failed to find Hover for %q", obj.Name()), err)
		return item, nil
	}
	if c.opts.fullDocumentation {
		item.Documentation = comment.Text()
	} else {
		item.Documentation = doc.Synopsis(comment.Text())
	}
	if internalastutil.Deprecation(comment) != "" {
		if c.snapshot.Options().CompletionTags {
			item.Tags = []protocol.CompletionItemTag{protocol.ComplDeprecated}
		} else if c.snapshot.Options().CompletionDeprecated {
			item.Deprecated = true
		}
	}

	return item, nil
}

// conversionEdits represents the string edits needed to make a type conversion
// of an expression.
type conversionEdits struct {
	prefix, suffix string
}

// formatConversion returns the edits needed to make a type conversion
// expression, including parentheses if necessary.
//
// Returns empty conversionEdits if convertTo is nil.
func (c *completer) formatConversion(convertTo types.Type) conversionEdits {
	if convertTo == nil {
		return conversionEdits{}
	}

	typeName := types.TypeString(convertTo, c.qual)
	switch t := convertTo.(type) {
	// We need extra parens when casting to these types. For example,
	// we need "(*int)(foo)", not "*int(foo)".
	case *types.Pointer, *types.Signature:
		typeName = "(" + typeName + ")"
	case *types.Basic:
		// If the types are incompatible (as determined by typeMatches), then we
		// must need a conversion here. However, if the target type is untyped,
		// don't suggest converting to e.g. "untyped float" (golang/go#62141).
		if t.Info()&types.IsUntyped != 0 {
			typeName = types.TypeString(types.Default(convertTo), c.qual)
		}
	}
	return conversionEdits{prefix: typeName + "(", suffix: ")"}
}

// importEdits produces the text edits necessary to add the given import to the current file.
func (c *completer) importEdits(imp *importInfo) ([]protocol.TextEdit, error) {
	if imp == nil {
		return nil, nil
	}

	pgf, err := c.pkg.File(protocol.URIFromPath(c.filename))
	if err != nil {
		return nil, err
	}

	return golang.ComputeImportFixEdits(c.snapshot.Options().Local, pgf.Src, &imports.ImportFix{
		StmtInfo: imports.ImportInfo{
			ImportPath: imp.importPath,
			Name:       imp.name,
		},
		// IdentName is unused on this path and is difficult to get.
		FixType: imports.AddImport,
	})
}

func (c *completer) formatBuiltin(ctx context.Context, cand candidate) (CompletionItem, error) {
	obj := cand.obj
	item := CompletionItem{
		Label:      obj.Name(),
		InsertText: obj.Name(),
		Score:      cand.score,
	}
	switch obj.(type) {
	case *types.Const:
		item.Kind = protocol.ConstantCompletion
	case *types.Builtin:
		item.Kind = protocol.FunctionCompletion
		sig, err := golang.NewBuiltinSignature(ctx, c.snapshot, obj.Name())
		if err != nil {
			return CompletionItem{}, err
		}
		item.Detail = "func" + sig.Format()
		item.snippet = &snippet.Builder{}
		// The signature inferred for a built-in is instantiated, so TypeParams=∅.
		c.functionCallSnippet(obj.Name(), sig.TypeParams(), sig.Params(), item.snippet)
	case *types.TypeName:
		if types.IsInterface(obj.Type()) {
			item.Kind = protocol.InterfaceCompletion
		} else {
			item.Kind = protocol.ClassCompletion
		}
	case *types.Nil:
		item.Kind = protocol.VariableCompletion
	}
	return item, nil
}

// decide if the type params (if any) should be part of the completion
// which only possible for types.Named and types.Signature
// (so far, only in receivers, e.g.; func (s *GENERIC[K, V])..., which is a types.Named)
func (c *completer) wantTypeParams() bool {
	// Need to be lexically in a receiver, and a child of an IndexListExpr
	// (but IndexListExpr only exists with go1.18)
	start := c.path[0].Pos()
	for i, nd := range c.path {
		if fd, ok := nd.(*ast.FuncDecl); ok {
			if i > 0 && fd.Recv != nil && start < fd.Recv.End() {
				return true
			} else {
				return false
			}
		}
	}
	return false
}

// inferableTypeParams returns the set of type parameters
// of sig that are constrained by (inferred from) the argument types.
func inferableTypeParams(sig *types.Signature) map[*types.TypeParam]bool {
	free := make(map[*types.TypeParam]bool)

	// visit adds to free all the free type parameters of t.
	var visit func(t types.Type)
	visit = func(t types.Type) {
		switch t := t.(type) {
		case *types.Array:
			visit(t.Elem())
		case *types.Chan:
			visit(t.Elem())
		case *types.Map:
			visit(t.Key())
			visit(t.Elem())
		case *types.Pointer:
			visit(t.Elem())
		case *types.Slice:
			visit(t.Elem())
		case *types.Interface:
			for method := range t.ExplicitMethods() {
				visit(method.Type())
			}
			for etyp := range t.EmbeddedTypes() {
				visit(etyp)
			}
		case *types.Union:
			for term := range t.Terms() {
				visit(term.Type())
			}
		case *types.Signature:
			if tp := t.TypeParams(); tp != nil {
				// Generic signatures only appear as the type of generic
				// function declarations, so this isn't really reachable.
				for tparam := range tp.TypeParams() {
					visit(tparam.Constraint())
				}
			}
			visit(t.Params())
			visit(t.Results())
		case *types.Tuple:
			for v := range t.Variables() {
				visit(v.Type())
			}
		case *types.Struct:
			for field := range t.Fields() {
				visit(field.Type())
			}
		case *types.TypeParam:
			free[t] = true
		case *types.Alias:
			visit(types.Unalias(t))
		case *types.Named:
			targs := t.TypeArgs()
			for t0 := range targs.Types() {
				visit(t0)
			}
		case *types.Basic:
			// nop
		default:
			panic(t)
		}
	}

	visit(sig.Params())

	// Perform induction through constraints.
restart:
	for tp := range sig.TypeParams().TypeParams() {
		if free[tp] {
			n := len(free)
			visit(tp.Constraint())
			if len(free) > n {
				goto restart // iterate until fixed point
			}
		}
	}
	return free
}


================================================
FILE: gopls/internal/golang/completion/fuzz.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"fmt"
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
)

// golang/go#51089
// *testing.F deserves special treatment as member use is constrained:
// The arguments to f.Fuzz are determined by the arguments to a previous f.Add
// Inside f.Fuzz only f.Failed and f.Name are allowed.
// PJW: are there other packages where we can deduce usage constraints?

// if we find fuzz completions, then return true, as those are the only completions to offer
func (c *completer) fuzz(testingF types.Type, imp *importInfo, cb func(candidate)) bool {
	// 1. inside f.Fuzz? (only f.Failed and f.Name)
	// 2. possible completing f.Fuzz?
	//    [Ident,SelectorExpr,Callexpr,ExprStmt,BlockiStmt,FuncDecl(Fuzz...)]
	// 3. before f.Fuzz, same (for 2., offer choice when looking at an F)

	mset := types.NewMethodSet(testingF)

	// does the path contain FuncLit as arg to f.Fuzz CallExpr?
	inside := false
Loop:
	for i, n := range c.path {
		switch v := n.(type) {
		case *ast.CallExpr:
			if len(v.Args) != 1 {
				continue Loop
			}
			if _, ok := v.Args[0].(*ast.FuncLit); !ok {
				continue
			}
			if s, ok := v.Fun.(*ast.SelectorExpr); !ok || s.Sel.Name != "Fuzz" {
				continue
			}
			if i > 2 { // avoid t.Fuzz itself in tests
				inside = true
				break Loop
			}
		}
	}
	if inside {
		for method := range mset.Methods() {
			o := method.Obj()
			if o.Name() == "Failed" || o.Name() == "Name" {
				cb(candidate{
					obj:         o,
					score:       stdScore,
					imp:         imp,
					addressable: true,
				})
			}
		}
		return true
	}
	// if it could be t.Fuzz, look for the preceding t.Add
	id, ok := c.path[0].(*ast.Ident)
	if ok && strings.HasPrefix("Fuzz", id.Name) {
		var add *ast.CallExpr
		f := func(n ast.Node) bool {
			if n == nil {
				return true
			}
			call, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}
			s, ok := call.Fun.(*ast.SelectorExpr)
			if !ok {
				return true
			}
			if s.Sel.Name != "Add" {
				return true
			}
			// Sel.X should be of type *testing.F
			got := c.pkg.TypesInfo().Types[s.X]
			if got.Type.String() == "*testing.F" {
				add = call
			}
			return false // because we're done...
		}
		// look at the enclosing FuzzFoo functions
		if len(c.path) < 2 {
			return false
		}
		n := c.path[len(c.path)-2]
		if _, ok := n.(*ast.FuncDecl); !ok {
			// the path should start with ast.File, ast.FuncDecl, ...
			// but it didn't, so give up
			return false
		}
		ast.Inspect(n, f)
		if add == nil {
			// looks like f.Fuzz without a preceding f.Add.
			// let the regular completion handle it.
			return false
		}

		lbl := "Fuzz(func(t *testing.T"
		for i, a := range add.Args {
			info := c.pkg.TypesInfo().TypeOf(a)
			if info == nil {
				return false // How could this happen, but better safe than panic.
			}
			lbl += fmt.Sprintf(", %c %s", 'a'+i, info)
		}
		lbl += ")"
		xx := CompletionItem{
			Label:         lbl,
			InsertText:    lbl,
			Kind:          protocol.FunctionCompletion,
			Depth:         0,
			Score:         10, // pretty confident the user should see this
			Documentation: "argument types from f.Add",
			isSlice:       false,
		}
		c.items = append(c.items, xx)
		for method := range mset.Methods() {
			o := method.Obj()
			if o.Name() != "Fuzz" {
				cb(candidate{
					obj:         o,
					score:       stdScore,
					imp:         imp,
					addressable: true,
				})
			}
		}
		return true // done
	}
	// let the standard processing take care of it instead
	return false
}


================================================
FILE: gopls/internal/golang/completion/keywords.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/astutil"
)

const (
	BREAK       = "break"
	CASE        = "case"
	CHAN        = "chan"
	CONST       = "const"
	CONTINUE    = "continue"
	DEFAULT     = "default"
	DEFER       = "defer"
	ELSE        = "else"
	FALLTHROUGH = "fallthrough"
	FOR         = "for"
	FUNC        = "func"
	GO          = "go"
	GOTO        = "goto"
	IF          = "if"
	IMPORT      = "import"
	INTERFACE   = "interface"
	MAP         = "map"
	PACKAGE     = "package"
	RANGE       = "range"
	RETURN      = "return"
	SELECT      = "select"
	STRUCT      = "struct"
	SWITCH      = "switch"
	TYPE        = "type"
	VAR         = "var"
)

// addKeywordCompletions offers keyword candidates appropriate at the position.
func (c *completer) addKeywordCompletions() {
	seen := make(map[string]bool)

	if c.wantTypeName() && c.inference.objType == nil {
		// If we want a type name but don't have an expected obj type,
		// include "interface", "struct", "func", "chan", and "map".

		// "interface" and "struct" are more common declaring named types.
		// Give them a higher score if we are in a type declaration.
		structIntf, funcChanMap := stdScore, highScore
		if len(c.path) > 1 {
			if _, namedDecl := c.path[1].(*ast.TypeSpec); namedDecl {
				structIntf, funcChanMap = highScore, stdScore
			}
		}

		c.addKeywordItems(seen, structIntf, STRUCT, INTERFACE)
		c.addKeywordItems(seen, funcChanMap, FUNC, CHAN, MAP)
	}

	// If we are at the file scope, only offer decl keywords. We don't
	// get *ast.Idents at the file scope because non-keyword identifiers
	// turn into *ast.BadDecl, not *ast.Ident.
	if len(c.path) == 1 || is[*ast.File](c.path[1]) {
		c.addKeywordItems(seen, stdScore, TYPE, CONST, VAR, FUNC, IMPORT)
		return
	} else if _, ok := c.path[0].(*ast.Ident); !ok {
		// Otherwise only offer keywords if the client is completing an identifier.
		return
	}

	if len(c.path) > 2 {
		// Offer "range" if we are in ast.ForStmt.Init. This is what the
		// AST looks like before "range" is typed, e.g. "for i := r<>".
		if loop, ok := c.path[2].(*ast.ForStmt); ok && loop.Init != nil && astutil.NodeContainsPos(loop.Init, c.pos) {
			c.addKeywordItems(seen, stdScore, RANGE)
		}
	}

	// Only suggest keywords if we are beginning a statement.
	switch n := c.path[1].(type) {
	case *ast.BlockStmt, *ast.ExprStmt:
		// OK - our ident must be at beginning of statement.
	case *ast.CommClause:
		// Make sure we aren't in the Comm statement.
		if !n.Colon.IsValid() || c.pos <= n.Colon {
			return
		}
	case *ast.CaseClause:
		// Make sure we aren't in the case List.
		if !n.Colon.IsValid() || c.pos <= n.Colon {
			return
		}
	default:
		return
	}

	// Filter out keywords depending on scope
	// Skip the first one because we want to look at the enclosing scopes
	path := c.path[1:]
	for i, n := range path {
		switch node := n.(type) {
		case *ast.CaseClause:
			// only recommend "fallthrough" and "break" within the bodies of a case clause
			if c.pos > node.Colon {
				c.addKeywordItems(seen, stdScore, BREAK)
				// "fallthrough" is only valid in switch statements.
				// A case clause is always nested within a block statement in a switch statement,
				// that block statement is nested within either a TypeSwitchStmt or a SwitchStmt.
				if i+2 >= len(path) {
					continue
				}
				if _, ok := path[i+2].(*ast.SwitchStmt); ok {
					c.addKeywordItems(seen, stdScore, FALLTHROUGH)
				}
			}
		case *ast.CommClause:
			if c.pos > node.Colon {
				c.addKeywordItems(seen, stdScore, BREAK)
			}
		case *ast.TypeSwitchStmt, *ast.SelectStmt, *ast.SwitchStmt:
			// if there is no default case yet, it's highly likely to add a default in switch.
			// we don't offer 'default' anymore if user has used it already in current switch.
			if !hasDefaultClause(node) {
				c.addKeywordItems(seen, highScore, CASE, DEFAULT)
			}
		case *ast.ForStmt, *ast.RangeStmt:
			c.addKeywordItems(seen, stdScore, BREAK, CONTINUE)
		// This is a bit weak, functions allow for many keywords
		case *ast.FuncDecl:
			if node.Body != nil && c.pos > node.Body.Lbrace {
				// requireReturnObj checks whether user must provide some objects after return.
				requireReturnObj := func(sig *ast.FuncType) bool {
					results := sig.Results
					if results == nil || results.List == nil {
						return false // nothing to return
					}
					// If any result is named, allow a bare return.
					for _, r := range results.List {
						for _, name := range r.Names {
							if name.Name != "_" {
								return false
							}
						}
					}
					return true
				}
				ret := RETURN
				if requireReturnObj(node.Type) {
					// as user must return something, we offer a space after return.
					// function literal inside a function will be affected by outer function,
					// but 'go fmt' will help to remove the ending space.
					// the benefit is greater than introducing an unnecessary space.
					ret += " "
				}

				c.addKeywordItems(seen, stdScore, DEFER, ret, FOR, GO, SWITCH, SELECT, IF, ELSE, VAR, CONST, GOTO, TYPE)
			}
		}
	}
}

// hasDefaultClause reports whether the given node contains a direct default case.
// It does not traverse child nodes to look for nested default clauses,
// and returns false if the node is not a switch statement.
func hasDefaultClause(node ast.Node) bool {
	var cases []ast.Stmt
	switch node := node.(type) {
	case *ast.TypeSwitchStmt:
		cases = node.Body.List
	case *ast.SelectStmt:
		cases = node.Body.List
	case *ast.SwitchStmt:
		cases = node.Body.List
	}
	for _, c := range cases {
		if clause, ok := c.(*ast.CaseClause); ok &&
			clause.List == nil { // default case
			return true
		}
	}
	return false
}

// addKeywordItems dedupes and adds completion items for the specified
// keywords with the specified score.
func (c *completer) addKeywordItems(seen map[string]bool, score float64, kws ...string) {
	for _, kw := range kws {
		if seen[kw] {
			continue
		}
		seen[kw] = true

		if matchScore := c.matcher.Score(kw); matchScore > 0 {
			c.items = append(c.items, CompletionItem{
				Label:      kw,
				Kind:       protocol.KeywordCompletion,
				InsertText: kw,
				Score:      score * float64(matchScore),
			})
		}
	}
}


================================================
FILE: gopls/internal/golang/completion/labels.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"
	"go/token"
	"math"
	"slices"
)

type labelType int

const (
	labelNone labelType = iota
	labelBreak
	labelContinue
	labelGoto
)

// wantLabelCompletion returns true if we want (only) label
// completions at the position.
func (c *completer) wantLabelCompletion() labelType {
	if _, ok := c.path[0].(*ast.Ident); ok && len(c.path) > 1 {
		// We want a label if we are an *ast.Ident child of a statement
		// that accepts a label, e.g. "break Lo<>".
		return takesLabel(c.path[1])
	}

	return labelNone
}

// takesLabel returns the corresponding labelType if n is a statement
// that accepts a label, otherwise labelNone.
func takesLabel(n ast.Node) labelType {
	if bs, ok := n.(*ast.BranchStmt); ok {
		switch bs.Tok {
		case token.BREAK:
			return labelBreak
		case token.CONTINUE:
			return labelContinue
		case token.GOTO:
			return labelGoto
		}
	}
	return labelNone
}

// labels adds completion items for labels defined in the enclosing
// function.
func (c *completer) labels(lt labelType) {
	if c.enclosingFunc == nil {
		return
	}

	addLabel := func(score float64, l *ast.LabeledStmt) {
		labelObj := c.pkg.TypesInfo().ObjectOf(l.Label)
		if labelObj != nil {
			c.deepState.enqueue(candidate{obj: labelObj, score: score})
		}
	}

	switch lt {
	case labelBreak, labelContinue:
		// "break" and "continue" only accept labels from enclosing statements.

		for i, p := range c.path {
			switch p := p.(type) {
			case *ast.FuncLit:
				// Labels are function scoped, so don't continue out of functions.
				return
			case *ast.LabeledStmt:
				switch p.Stmt.(type) {
				case *ast.ForStmt, *ast.RangeStmt:
					// Loop labels can be used for "break" or "continue".
					addLabel(highScore*math.Pow(.99, float64(i)), p)
				case *ast.SwitchStmt, *ast.SelectStmt, *ast.TypeSwitchStmt:
					// Switch and select labels can be used only for "break".
					if lt == labelBreak {
						addLabel(highScore*math.Pow(.99, float64(i)), p)
					}
				}
			}
		}
	case labelGoto:
		// Goto accepts any label in the same function not in a nested
		// block. It also doesn't take labels that would jump across
		// variable definitions, but ignore that case for now.
		ast.Inspect(c.enclosingFunc.body, func(n ast.Node) bool {
			if n == nil {
				return false
			}

			switch n := n.(type) {
			// Only search into block-like nodes enclosing our "goto".
			// This prevents us from finding labels in nested blocks.
			case *ast.BlockStmt, *ast.CommClause, *ast.CaseClause:
				return slices.Contains(c.path, n)
			case *ast.LabeledStmt:
				addLabel(highScore, n)
			}

			return true
		})
	}
}


================================================
FILE: gopls/internal/golang/completion/literal.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"context"
	"fmt"
	"go/types"
	"strings"
	"unicode"

	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typesinternal"
)

// literal generates composite literal, function literal, and make()
// completion items.
func (c *completer) literal(ctx context.Context, literalType types.Type, imp *importInfo) {
	if !c.opts.snippets {
		return
	}

	expType := c.inference.objType

	if c.inference.matchesVariadic(literalType) {
		// Don't offer literal slice candidates for variadic arguments.
		// For example, don't offer "[]interface{}{}" in "fmt.Print(<>)".
		return
	}

	// Avoid literal candidates if the expected type is an empty
	// interface. It isn't very useful to suggest a literal candidate of
	// every possible type.
	if expType != nil && isEmptyInterface(expType) {
		return
	}

	// We handle unnamed literal completions explicitly before searching
	// for candidates. Avoid named-type literal completions for
	// unnamed-type expected type since that results in duplicate
	// candidates. For example, in
	//
	// type mySlice []int
	// var []int = <>
	//
	// don't offer "mySlice{}" since we have already added a candidate
	// of "[]int{}".

	// TODO(adonovan): think about aliases:
	// they should probably be treated more like Named.
	// Should this use Deref not Unpointer?
	if is[*types.Named](types.Unalias(literalType)) &&
		expType != nil &&
		!is[*types.Named](types.Unalias(typesinternal.Unpointer(expType))) {

		return
	}

	// Check if an object of type literalType would match our expected type.
	cand := candidate{
		obj: c.fakeObj(literalType),
	}

	switch literalType.Underlying().(type) {
	// These literal types are addressable (e.g. "&[]int{}"), others are
	// not (e.g. can't do "&(func(){})").
	case *types.Struct, *types.Array, *types.Slice, *types.Map:
		cand.addressable = true
	}

	// Only suggest a literal conversion if the exact type is known.
	if !c.matchingCandidate(&cand) || (cand.convertTo != nil && !c.inference.needsExactType) {
		return
	}

	var (
		qual       = c.qual
		sel        = enclosingSelector(c.path, c.pos)
		conversion conversionEdits
	)

	if cand.convertTo != nil {
		conversion = c.formatConversion(cand.convertTo)
	}

	// Don't qualify the type name if we are in a selector expression
	// since the package name is already present.
	if sel != nil {
		qual = func(_ *types.Package) string { return "" }
	}

	snip, typeName := c.typeNameSnippet(literalType, qual)

	// A type name of "[]int" doesn't work very will with the matcher
	// since "[" isn't a valid identifier prefix. Here we strip off the
	// slice (and array) prefix yielding just "int".
	matchName := typeName
	switch t := literalType.(type) {
	case *types.Slice:
		matchName = types.TypeString(t.Elem(), qual)
	case *types.Array:
		matchName = types.TypeString(t.Elem(), qual)
	}

	addlEdits, err := c.importEdits(imp)
	if err != nil {
		event.Error(ctx, "error adding import for literal candidate", err)
		return
	}

	// If prefix matches the type name, client may want a composite literal.
	if score := c.matcher.Score(matchName); score > 0 {
		if cand.hasMod(reference) {
			if sel != nil {
				// If we are in a selector we must place the "&" before the selector.
				// For example, "foo.B<>" must complete to "&foo.Bar{}", not
				// "foo.&Bar{}".
				edits, err := c.editText(sel.Pos(), sel.Pos(), "&")
				if err != nil {
					event.Error(ctx, "error making edit for literal pointer completion", err)
					return
				}
				addlEdits = append(addlEdits, edits...)
			} else {
				// Otherwise we can stick the "&" directly before the type name.
				typeName = "&" + typeName
				snip.PrependText("&")
			}
		}

		switch t := literalType.Underlying().(type) {
		case *types.Struct, *types.Array, *types.Slice, *types.Map:
			item := c.compositeLiteral(t, snip.Clone(), typeName, float64(score), addlEdits)
			item.addConversion(c, conversion)
			c.items = append(c.items, item)
		case *types.Signature:
			// Add a literal completion for a signature type that implements
			// an interface. For example, offer "http.HandlerFunc()" when
			// expected type is "http.Handler".
			if expType != nil && types.IsInterface(expType) {
				if item, ok := c.basicLiteral(t, snip.Clone(), typeName, float64(score), addlEdits); ok {
					item.addConversion(c, conversion)
					c.items = append(c.items, item)
				}
			}
		case *types.Basic:
			// Add a literal completion for basic types that implement our
			// expected interface (e.g. named string type http.Dir
			// implements http.FileSystem), or are identical to our expected
			// type (i.e. yielding a type conversion such as "float64()").
			if expType != nil && (types.IsInterface(expType) || types.Identical(expType, literalType)) {
				if item, ok := c.basicLiteral(t, snip.Clone(), typeName, float64(score), addlEdits); ok {
					item.addConversion(c, conversion)
					c.items = append(c.items, item)
				}
			}
		}
	}

	// If prefix matches "make", client may want a "make()"
	// invocation. We also include the type name to allow for more
	// flexible fuzzy matching.
	if score := c.matcher.Score("make." + matchName); !cand.hasMod(reference) && score > 0 {
		switch literalType.Underlying().(type) {
		case *types.Slice:
			// The second argument to "make()" for slices is required, so default to "0".
			item := c.makeCall(snip.Clone(), typeName, "0", float64(score), addlEdits)
			item.addConversion(c, conversion)
			c.items = append(c.items, item)
		case *types.Map, *types.Chan:
			// Maps and channels don't require the second argument, so omit
			// to keep things simple for now.
			item := c.makeCall(snip.Clone(), typeName, "", float64(score), addlEdits)
			item.addConversion(c, conversion)
			c.items = append(c.items, item)
		}
	}

	// If prefix matches "func", client may want a function literal.
	if score := c.matcher.Score("func"); !cand.hasMod(reference) && score > 0 && (expType == nil || !types.IsInterface(expType)) {
		switch t := literalType.Underlying().(type) {
		case *types.Signature:
			if item, ok := c.functionLiteral(ctx, t, float64(score)); ok {
				item.addConversion(c, conversion)
				c.items = append(c.items, item)
			}
		}
	}
}

// literalCandidateScore is the base score for literal candidates.
// Literal candidates match the expected type so they should be high
// scoring, but we want them ranked below lexical objects of the
// correct type, so scale down highScore.
const literalCandidateScore = highScore / 2

// functionLiteral returns a function literal completion item for the
// given signature, if applicable.
func (c *completer) functionLiteral(ctx context.Context, sig *types.Signature, matchScore float64) (CompletionItem, bool) {
	snip := &snippet.Builder{}
	snip.WriteText("func(")

	// First we generate names for each param and keep a seen count so
	// we know if we need to uniquify param names. For example,
	// "func(int)" will become "func(i int)", but "func(int, int64)"
	// will become "func(i1 int, i2 int64)".
	var (
		paramNames     = make([]string, sig.Params().Len())
		paramNameCount = make(map[string]int)
		hasTypeParams  bool
	)
	for i := range sig.Params().Len() {
		var (
			p    = sig.Params().At(i)
			name = p.Name()
		)

		if tp, _ := types.Unalias(p.Type()).(*types.TypeParam); tp != nil && !c.typeParamInScope(tp) {
			hasTypeParams = true
		}

		if name == "" {
			// If the param has no name in the signature, guess a name based
			// on the type. Use an empty qualifier to ignore the package.
			// For example, we want to name "http.Request" "r", not "hr".
			typeName, err := golang.FormatVarType(ctx, c.snapshot, c.pkg, p,
				func(p *types.Package) string { return "" },
				func(golang.PackageName, golang.ImportPath, golang.PackagePath) string { return "" })
			if err != nil {
				// In general, the only error we should encounter while formatting is
				// context cancellation.
				if ctx.Err() == nil {
					event.Error(ctx, "formatting var type", err)
				}
				return CompletionItem{}, false
			}
			name = abbreviateTypeName(typeName)
		}
		paramNames[i] = name
		if name != "_" {
			paramNameCount[name]++
		}
	}

	for n, c := range paramNameCount {
		// Any names we saw more than once will need a unique suffix added
		// on. Reset the count to 1 to act as the suffix for the first
		// name.
		if c >= 2 {
			paramNameCount[n] = 1
		} else {
			delete(paramNameCount, n)
		}
	}

	for i := range sig.Params().Len() {
		if hasTypeParams && !c.opts.placeholders {
			// If there are type params in the args then the user must
			// choose the concrete types. If placeholders are disabled just
			// drop them between the parens and let them fill things in.
			snip.WritePlaceholder(nil)
			break
		}

		if i > 0 {
			snip.WriteText(", ")
		}

		var (
			p    = sig.Params().At(i)
			name = paramNames[i]
		)

		// Uniquify names by adding on an incrementing numeric suffix.
		if idx, found := paramNameCount[name]; found {
			paramNameCount[name]++
			name = fmt.Sprintf("%s%d", name, idx)
		}

		if name != p.Name() && c.opts.placeholders {
			// If we didn't use the signature's param name verbatim then we
			// may have chosen a poor name. Give the user a placeholder so
			// they can easily fix the name.
			snip.WritePlaceholder(func(b *snippet.Builder) {
				b.WriteText(name)
			})
		} else {
			snip.WriteText(name)
		}

		// If the following param's type is identical to this one, omit
		// this param's type string. For example, emit "i, j int" instead
		// of "i int, j int".
		if i == sig.Params().Len()-1 || !types.Identical(p.Type(), sig.Params().At(i+1).Type()) {
			snip.WriteText(" ")
			typeStr, err := golang.FormatVarType(ctx, c.snapshot, c.pkg, p, c.qual, c.mq)
			if err != nil {
				// In general, the only error we should encounter while formatting is
				// context cancellation.
				if ctx.Err() == nil {
					event.Error(ctx, "formatting var type", err)
				}
				return CompletionItem{}, false
			}
			if sig.Variadic() && i == sig.Params().Len()-1 {
				typeStr = strings.Replace(typeStr, "[]", "...", 1)
			}

			if tp, ok := types.Unalias(p.Type()).(*types.TypeParam); ok && !c.typeParamInScope(tp) {
				snip.WritePlaceholder(func(snip *snippet.Builder) {
					snip.WriteText(typeStr)
				})
			} else {
				snip.WriteText(typeStr)
			}
		}
	}
	snip.WriteText(")")

	results := sig.Results()
	if results.Len() > 0 {
		snip.WriteText(" ")
	}

	resultsNeedParens := results.Len() > 1 ||
		results.Len() == 1 && results.At(0).Name() != ""

	var resultHasTypeParams bool
	for v := range results.Variables() {
		if tp, ok := types.Unalias(v.Type()).(*types.TypeParam); ok && !c.typeParamInScope(tp) {
			resultHasTypeParams = true
		}
	}

	if resultsNeedParens {
		snip.WriteText("(")
	}
	for i := range results.Len() {
		if resultHasTypeParams && !c.opts.placeholders {
			// Leave an empty tabstop if placeholders are disabled and there
			// are type args that need specifying.
			snip.WritePlaceholder(nil)
			break
		}

		if i > 0 {
			snip.WriteText(", ")
		}
		r := results.At(i)
		if name := r.Name(); name != "" {
			snip.WriteText(name + " ")
		}

		text, err := golang.FormatVarType(ctx, c.snapshot, c.pkg, r, c.qual, c.mq)
		if err != nil {
			// In general, the only error we should encounter while formatting is
			// context cancellation.
			if ctx.Err() == nil {
				event.Error(ctx, "formatting var type", err)
			}
			return CompletionItem{}, false
		}
		if tp, ok := types.Unalias(r.Type()).(*types.TypeParam); ok && !c.typeParamInScope(tp) {
			snip.WritePlaceholder(func(snip *snippet.Builder) {
				snip.WriteText(text)
			})
		} else {
			snip.WriteText(text)
		}
	}
	if resultsNeedParens {
		snip.WriteText(")")
	}

	snip.WriteText(" {")
	snip.WriteFinalTabstop()
	snip.WriteText("}")

	return CompletionItem{
		Label:   "func(...) {}",
		Score:   matchScore * literalCandidateScore,
		Kind:    protocol.VariableCompletion,
		snippet: snip,
	}, true
}

// conventionalAcronyms contains conventional acronyms for type names
// in lower case. For example, "ctx" for "context" and "err" for "error".
//
// Keep this up to date with golang.conventionalVarNames.
var conventionalAcronyms = map[string]string{
	"context":        "ctx",
	"error":          "err",
	"tx":             "tx",
	"responsewriter": "w",
}

// abbreviateTypeName abbreviates type names into acronyms. For
// example, "fooBar" is abbreviated "fb". Care is taken to ignore
// non-identifier runes. For example, "[]int" becomes "i", and
// "struct { i int }" becomes "s".
func abbreviateTypeName(s string) string {
	// Trim off leading non-letters. We trim everything between "[" and
	// "]" to handle array types like "[someConst]int".
	var inBracket bool
	s = strings.TrimFunc(s, func(r rune) bool {
		if inBracket {
			inBracket = r != ']'
			return true
		}

		if r == '[' {
			inBracket = true
		}

		return !unicode.IsLetter(r)
	})

	if acr, ok := conventionalAcronyms[strings.ToLower(s)]; ok {
		return acr
	}

	return golang.AbbreviateVarName(s)
}

// compositeLiteral returns a composite literal completion item for the given typeName.
// T is an (unnamed, unaliased) struct, array, slice, or map type.
func (c *completer) compositeLiteral(T types.Type, snip *snippet.Builder, typeName string, matchScore float64, edits []protocol.TextEdit) CompletionItem {
	snip.WriteText("{")
	// Don't put the tab stop inside the composite literal curlies "{}"
	// for structs that have no accessible fields.
	if strct, ok := T.(*types.Struct); !ok || fieldsAccessible(strct, c.pkg.Types()) {
		snip.WriteFinalTabstop()
	}
	snip.WriteText("}")

	nonSnippet := typeName + "{}"

	return CompletionItem{
		Label:               nonSnippet,
		InsertText:          nonSnippet,
		Score:               matchScore * literalCandidateScore,
		Kind:                protocol.VariableCompletion,
		AdditionalTextEdits: edits,
		snippet:             snip,
	}
}

// basicLiteral returns a literal completion item for the given basic
// type name typeName.
//
// If T is untyped, this function returns false.
func (c *completer) basicLiteral(T types.Type, snip *snippet.Builder, typeName string, matchScore float64, edits []protocol.TextEdit) (CompletionItem, bool) {
	// Never give type conversions like "untyped int()".
	if isUntyped(T) {
		return CompletionItem{}, false
	}

	snip.WriteText("(")
	snip.WriteFinalTabstop()
	snip.WriteText(")")

	nonSnippet := typeName + "()"

	return CompletionItem{
		Label:               nonSnippet,
		InsertText:          nonSnippet,
		Detail:              T.String(),
		Score:               matchScore * literalCandidateScore,
		Kind:                protocol.VariableCompletion,
		AdditionalTextEdits: edits,
		snippet:             snip,
	}, true
}

// makeCall returns a completion item for a "make()" call given a specific type.
func (c *completer) makeCall(snip *snippet.Builder, typeName string, secondArg string, matchScore float64, edits []protocol.TextEdit) CompletionItem {
	// Keep it simple and don't add any placeholders for optional "make()" arguments.

	snip.PrependText("make(")
	if secondArg != "" {
		snip.WriteText(", ")
		snip.WritePlaceholder(func(b *snippet.Builder) {
			if c.opts.placeholders {
				b.WriteText(secondArg)
			}
		})
	}
	snip.WriteText(")")

	var nonSnippet strings.Builder
	nonSnippet.WriteString("make(" + typeName)
	if secondArg != "" {
		nonSnippet.WriteString(", ")
		nonSnippet.WriteString(secondArg)
	}
	nonSnippet.WriteByte(')')

	return CompletionItem{
		Label:      nonSnippet.String(),
		InsertText: nonSnippet.String(),
		// make() should be just below other literal completions
		Score:               matchScore * literalCandidateScore * 0.99,
		Kind:                protocol.FunctionCompletion,
		AdditionalTextEdits: edits,
		snippet:             snip,
	}
}

// Create a snippet for a type name where type params become placeholders.
func (c *completer) typeNameSnippet(literalType types.Type, qual types.Qualifier) (*snippet.Builder, string) {
	var (
		snip     snippet.Builder
		typeName string
		tparams  *types.TypeParamList
	)

	t, ok := literalType.(typesinternal.NamedOrAlias) // = *Named | *Alias
	if ok {
		tparams = t.TypeParams()
	}
	if tparams.Len() > 0 && !c.fullyInstantiated(t) {
		// tparams.Len() > 0 implies t != nil.
		// Inv: t is not "error" or "unsafe.Pointer", so t.Obj() != nil and has a Pkg().

		// We are not "fully instantiated" meaning we have type params that must be specified.
		if pkg := qual(t.Obj().Pkg()); pkg != "" {
			typeName = pkg + "."
		}

		// We do this to get "someType" instead of "someType[T]".
		typeName += t.Obj().Name()
		snip.WriteText(typeName + "[")

		if c.opts.placeholders {
			for i := range tparams.Len() {
				if i > 0 {
					snip.WriteText(", ")
				}
				snip.WritePlaceholder(func(snip *snippet.Builder) {
					snip.WriteText(types.TypeString(tparams.At(i), qual))
				})
			}
		} else {
			snip.WritePlaceholder(nil)
		}
		snip.WriteText("]")
		typeName += "[...]"
	} else {
		// We don't have unspecified type params so use default type formatting.
		typeName = types.TypeString(literalType, qual)
		snip.WriteText(typeName)
	}

	return &snip, typeName
}

// fullyInstantiated reports whether all of t's type params have
// specified type args.
func (c *completer) fullyInstantiated(t typesinternal.NamedOrAlias) bool {
	targs := t.TypeArgs()
	tparams := t.TypeParams()

	if tparams.Len() != targs.Len() {
		return false
	}

	for targ := range targs.Types() {

		// The expansion of an alias can have free type parameters,
		// whether or not the alias itself has type parameters:
		//
		//   func _[K comparable]() {
		//     type Set      = map[K]bool // free(Set)      = {K}
		//     type MapTo[V] = map[K]V    // free(Map[foo]) = {V}
		//   }
		//
		// So, we must Unalias.
		switch targ := types.Unalias(targ).(type) {
		case *types.TypeParam:
			// A *TypeParam only counts as specified if it is currently in
			// scope (i.e. we are in a generic definition).
			if !c.typeParamInScope(targ) {
				return false
			}
		case *types.Named:
			if !c.fullyInstantiated(targ) {
				return false
			}
		}
	}
	return true
}

// typeParamInScope returns whether tp's object is in scope at c.pos.
// This tells you whether you are in a generic definition and can
// assume tp has been specified.
func (c *completer) typeParamInScope(tp *types.TypeParam) bool {
	obj := tp.Obj()
	if obj == nil {
		return false
	}

	scope := c.innermostScope()
	if scope == nil {
		return false
	}

	_, foundObj := scope.LookupParent(obj.Name(), c.pos)
	return obj == foundObj
}


================================================
FILE: gopls/internal/golang/completion/newfile.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"bytes"
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
)

// NewFile returns a document change to complete an empty Go source file. Document change may be nil.
func NewFile(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) (*protocol.DocumentChange, error) {
	if !snapshot.Options().NewGoFileHeader {
		return nil, nil
	}
	content, err := fh.Content()
	if err != nil {
		return nil, err
	}
	if len(content) != 0 {
		return nil, fmt.Errorf("file is not empty")
	}
	meta, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
	if err != nil {
		return nil, err
	}
	var buf bytes.Buffer
	// Copy the copyright header from the first existing file that has one.
	for _, fileURI := range meta.GoFiles {
		if fileURI == fh.URI() {
			continue
		}
		fh, err := snapshot.ReadFile(ctx, fileURI)
		if err != nil {
			continue
		}
		pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			continue
		}
		if group := golang.CopyrightComment(pgf.File); group != nil {
			text, err := pgf.NodeText(group)
			if err != nil {
				continue
			}
			buf.Write(text)
			buf.WriteString("\n\n")
			break
		}
	}

	pkgName, err := bestPackage(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}

	fmt.Fprintf(&buf, "package %s\n", pkgName)
	change := protocol.DocumentChangeEdit(fh, []protocol.TextEdit{{
		Range:   protocol.Range{}, // insert at start of file
		NewText: buf.String(),
	}})

	return &change, nil
}


================================================
FILE: gopls/internal/golang/completion/package.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/parser"
	"go/scanner"
	"go/token"
	"go/types"
	"path/filepath"
	"sort"
	"strings"
	"unicode"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/fuzzy"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// bestPackage offers the best package name for a package declaration when
// one is not present in the given file.
func bestPackage(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) (string, error) {
	suggestions, err := packageSuggestions(ctx, snapshot, uri, "")
	if err != nil {
		return "", err
	}
	// sort with the same way of sortItems.
	sort.SliceStable(suggestions, func(i, j int) bool {
		if suggestions[i].score != suggestions[j].score {
			return suggestions[i].score > suggestions[j].score
		}
		return suggestions[i].name < suggestions[j].name
	})

	return suggestions[0].name, nil
}

// packageClauseCompletions offers completions for a package declaration when
// one is not present in the given file.
func packageClauseCompletions(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, position protocol.Position) ([]CompletionItem, *Selection, error) {
	// We know that the AST for this file will be empty due to the missing
	// package declaration, but parse it anyway to get a mapper.
	// TODO(adonovan): opt: there's no need to parse just to get a mapper.
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, nil, err
	}

	offset, err := pgf.Mapper.PositionOffset(position)
	if err != nil {
		return nil, nil, err
	}
	surrounding, err := packageCompletionSurrounding(pgf, offset)
	if err != nil {
		return nil, nil, fmt.Errorf("invalid position for package completion: %w", err)
	}

	packageSuggestions, err := packageSuggestions(ctx, snapshot, fh.URI(), "")
	if err != nil {
		return nil, nil, err
	}

	var items []CompletionItem
	for _, pkg := range packageSuggestions {
		insertText := fmt.Sprintf("package %s", pkg.name)
		items = append(items, CompletionItem{
			Label:      insertText,
			Kind:       protocol.ModuleCompletion,
			InsertText: insertText,
			Score:      pkg.score,
		})
	}
	sortItems(items)
	return items, surrounding, nil
}

// packageCompletionSurrounding returns surrounding for package completion if a
// package completions can be suggested at a given cursor offset. A valid location
// for package completion is above any declarations or import statements.
func packageCompletionSurrounding(pgf *parsego.File, offset int) (*Selection, error) {
	m := pgf.Mapper
	// If the file lacks a package declaration, the parser will return an empty
	// AST. As a work-around, try to parse an expression from the file contents.
	fset := token.NewFileSet()
	expr, _ := parser.ParseExprFrom(fset, m.URI.Path(), pgf.Src, parser.Mode(0))
	if expr == nil {
		return nil, fmt.Errorf("unparsable file (%s)", m.URI)
	}
	tok := fset.File(expr.Pos())
	cursor := tok.Pos(offset)

	// If we were able to parse out an identifier as the first expression from
	// the file, it may be the beginning of a package declaration ("pack ").
	// We can offer package completions if the cursor is in the identifier.
	if name, ok := expr.(*ast.Ident); ok {
		if cursor >= name.Pos() && cursor <= name.End() {
			if !strings.HasPrefix(PACKAGE, name.Name) {
				return nil, fmt.Errorf("cursor in non-matching ident")
			}
			sel := &Selection{
				content: name.Name,
				cursor:  cursor,
				tokFile: tok,
				start:   name.Pos(),
				end:     name.End(),
				mapper:  m,
			}
			sel.check()
			return sel, nil
		}
	}

	// The file is invalid, but it contains an expression that we were able to
	// parse. We will use this expression to construct the cursor's
	// "surrounding".

	// First, consider the possibility that we have a valid "package" keyword
	// with an empty package name ("package "). "package" is parsed as an
	// *ast.BadDecl since it is a keyword.
	start, err := safetoken.Offset(tok, expr.Pos())
	if err != nil {
		return nil, err
	}
	if offset > start && string(bytes.TrimRight(pgf.Src[start:offset], " ")) == PACKAGE {
		sel := &Selection{
			content: string(pgf.Src[start:offset]),
			cursor:  cursor,
			tokFile: tok,
			start:   expr.Pos(),
			end:     cursor,
			mapper:  m,
		}
		sel.check()
		return sel, nil
	}

	// If the cursor is after the start of the expression, no package
	// declaration will be valid.
	if cursor > expr.Pos() {
		return nil, fmt.Errorf("cursor after expression")
	}

	// If the cursor is in a comment, don't offer any completions.
	if cursorInComment(tok, cursor, m.Content) {
		return nil, fmt.Errorf("cursor in comment")
	}

	// The surrounding range in this case is the cursor.
	sel := &Selection{
		content: "",
		tokFile: tok,
		start:   cursor,
		end:     cursor,
		cursor:  cursor,
		mapper:  m,
	}
	sel.check()
	return sel, nil
}

func cursorInComment(file *token.File, cursor token.Pos, src []byte) bool {
	var s scanner.Scanner
	s.Init(file, src, func(_ token.Position, _ string) {}, scanner.ScanComments)
	for {
		pos, tok, lit := s.Scan()
		if pos <= cursor && cursor <= token.Pos(int(pos)+len(lit)) {
			return tok == token.COMMENT
		}
		if tok == token.EOF {
			break
		}
	}
	return false
}

// packageNameCompletions returns name completions for a package clause using
// the current name as prefix.
func (c *completer) packageNameCompletions(ctx context.Context, fileURI protocol.DocumentURI, name *ast.Ident) error {
	cursor := int(c.pos - name.NamePos)
	if cursor < 0 || cursor > len(name.Name) {
		return errors.New("cursor is not in package name identifier")
	}

	c.completionContext.packageCompletion = true

	prefix := name.Name[:cursor]
	packageSuggestions, err := packageSuggestions(ctx, c.snapshot, fileURI, prefix)
	if err != nil {
		return err
	}

	for _, pkg := range packageSuggestions {
		c.deepState.enqueue(pkg)
	}
	return nil
}

// packageSuggestions returns a list of packages from workspace packages that
// have the given prefix and are used in the same directory as the given
// file. This also includes test packages for these packages (<pkg>_test) and
// the directory name itself.
func packageSuggestions(ctx context.Context, snapshot *cache.Snapshot, fileURI protocol.DocumentURI, prefix string) (packages []candidate, err error) {
	active, err := snapshot.WorkspaceMetadata(ctx)
	if err != nil {
		return nil, err
	}

	toCandidate := func(name string, score float64) candidate {
		obj := types.NewPkgName(0, nil, name, types.NewPackage("", name))
		return candidate{obj: obj, name: name, detail: name, score: score}
	}

	var currentPackageName string
	// TODO: consider propagating error.
	if md, err := snapshot.NarrowestMetadataForFile(ctx, fileURI); err == nil {
		currentPackageName = string(md.Name)
	}

	matcher := fuzzy.NewMatcher(prefix)

	// Always try to suggest a main package
	defer func() {
		mainScore := lowScore
		if currentPackageName == "main" {
			mainScore = highScore
		}
		if score := float64(matcher.Score("main")); score > 0 {
			packages = append(packages, toCandidate("main", score*mainScore))
		}
	}()

	dirPath := fileURI.DirPath()
	dirName := filepath.Base(dirPath)
	if !isValidDirName(dirName) {
		return packages, nil
	}
	pkgName := convertDirNameToPkgName(dirName)

	seenPkgs := make(map[golang.PackageName]struct{})

	// The `go` command by default only allows one package per directory but we
	// support multiple package suggestions since gopls is build system agnostic.
	for _, mp := range active {
		if mp.Name == "main" || mp.Name == "" {
			continue
		}
		if _, ok := seenPkgs[mp.Name]; ok {
			continue
		}

		// Only add packages that are previously used in the current directory.
		var relevantPkg bool
		for _, uri := range mp.CompiledGoFiles {
			if uri.DirPath() == dirPath {
				relevantPkg = true
				break
			}
		}
		if !relevantPkg {
			continue
		}

		// Add a found package used in current directory as a high relevance
		// suggestion and the test package for it as a medium relevance
		// suggestion.
		if score := float64(matcher.Score(string(mp.Name))); score > 0 {
			packages = append(packages, toCandidate(string(mp.Name), score*highScore))
		}
		seenPkgs[mp.Name] = struct{}{}

		testPkgName := mp.Name + "_test"
		if _, ok := seenPkgs[testPkgName]; ok || strings.HasSuffix(string(mp.Name), "_test") {
			continue
		}
		if score := float64(matcher.Score(string(testPkgName))); score > 0 {
			packages = append(packages, toCandidate(string(testPkgName), score*stdScore))
		}
		seenPkgs[testPkgName] = struct{}{}
	}

	if _, ok := seenPkgs[pkgName]; !ok {
		// Add current directory name as a low relevance suggestion.
		dirNameScore := lowScore
		// if current package name is empty, the dir name is the best choice.
		if currentPackageName == "" {
			dirNameScore = highScore
		}
		if score := float64(matcher.Score(string(pkgName))); score > 0 {
			packages = append(packages, toCandidate(string(pkgName), score*dirNameScore))
		}

		testPkgName := pkgName + "_test"
		if score := float64(matcher.Score(string(testPkgName))); score > 0 {
			packages = append(packages, toCandidate(string(testPkgName), score*dirNameScore))
		}
	}

	return packages, nil
}

// isValidDirName checks whether the passed directory name can be used in
// a package path. Requirements for a package path can be found here:
// https://golang.org/ref/mod#go-mod-file-ident.
func isValidDirName(dirName string) bool {
	if dirName == "" {
		return false
	}

	for i, ch := range dirName {
		if isLetter(ch) || isDigit(ch) {
			continue
		}
		if i == 0 {
			// Directory name can start only with '_'. '.' is not allowed in module paths.
			// '-' and '~' are not allowed because elements of package paths must be
			// safe command-line arguments.
			if ch == '_' {
				continue
			}
		} else {
			// Modules path elements can't end with '.'
			if isAllowedPunctuation(ch) && (i != len(dirName)-1 || ch != '.') {
				continue
			}
		}

		return false
	}
	return true
}

// convertDirNameToPkgName converts a valid directory name to a valid package name.
// It leaves only letters and digits. All letters are mapped to lower case.
func convertDirNameToPkgName(dirName string) golang.PackageName {
	var buf bytes.Buffer
	for _, ch := range dirName {
		switch {
		case isLetter(ch):
			buf.WriteRune(unicode.ToLower(ch))

		case buf.Len() != 0 && isDigit(ch):
			buf.WriteRune(ch)
		}
	}
	return golang.PackageName(buf.String())
}

// isLetter and isDigit allow only ASCII characters because
// "Each path element is a non-empty string made of up ASCII letters,
// ASCII digits, and limited ASCII punctuation"
// (see https://golang.org/ref/mod#go-mod-file-ident).

func isLetter(ch rune) bool {
	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z'
}

func isDigit(ch rune) bool {
	return '0' <= ch && ch <= '9'
}

func isAllowedPunctuation(ch rune) bool {
	return ch == '_' || ch == '-' || ch == '~' || ch == '.'
}


================================================
FILE: gopls/internal/golang/completion/package_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"testing"

	"golang.org/x/tools/gopls/internal/golang"
)

func TestIsValidDirName(t *testing.T) {
	tests := []struct {
		dirName string
		valid   bool
	}{
		{dirName: "", valid: false},
		//
		{dirName: "a", valid: true},
		{dirName: "abcdef", valid: true},
		{dirName: "AbCdEf", valid: true},
		//
		{dirName: "1a35", valid: true},
		{dirName: "a16", valid: true},
		//
		{dirName: "_a", valid: true},
		{dirName: "a_", valid: true},
		//
		{dirName: "~a", valid: false},
		{dirName: "a~", valid: true},
		//
		{dirName: "-a", valid: false},
		{dirName: "a-", valid: true},
		//
		{dirName: ".a", valid: false},
		{dirName: "a.", valid: false},
		//
		{dirName: "a~_b--c.-e", valid: true},
		{dirName: "~a~_b--c.-e", valid: false},
		{dirName: "a~_b--c.-e--~", valid: true},
		{dirName: "a~_b--2134dc42.-e6--~", valid: true},
		{dirName: "abc`def", valid: false},
		{dirName: "тест", valid: false},
		{dirName: "你好", valid: false},
	}
	for _, tt := range tests {
		valid := isValidDirName(tt.dirName)
		if tt.valid != valid {
			t.Errorf("%s: expected %v, got %v", tt.dirName, tt.valid, valid)
		}
	}
}

func TestConvertDirNameToPkgName(t *testing.T) {
	tests := []struct {
		dirName string
		pkgName golang.PackageName
	}{
		{dirName: "a", pkgName: "a"},
		{dirName: "abcdef", pkgName: "abcdef"},
		{dirName: "AbCdEf", pkgName: "abcdef"},
		{dirName: "1a35", pkgName: "a35"},
		{dirName: "14a35", pkgName: "a35"},
		{dirName: "a16", pkgName: "a16"},
		{dirName: "_a", pkgName: "a"},
		{dirName: "a_", pkgName: "a"},
		{dirName: "a~", pkgName: "a"},
		{dirName: "a-", pkgName: "a"},
		{dirName: "a~_b--c.-e", pkgName: "abce"},
		{dirName: "a~_b--c.-e--~", pkgName: "abce"},
		{dirName: "a~_b--2134dc42.-e6--~", pkgName: "ab2134dc42e6"},
	}
	for _, tt := range tests {
		pkgName := convertDirNameToPkgName(tt.dirName)
		if tt.pkgName != pkgName {
			t.Errorf("%s: expected %v, got %v", tt.dirName, tt.pkgName, pkgName)
			continue
		}
	}
}


================================================
FILE: gopls/internal/golang/completion/postfix_snippets.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"log"
	"reflect"
	"strings"
	"sync"
	"text/template"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/typesinternal"
)

// Postfix snippets are artificial methods that allow the user to
// compose common operations in an "argument oriented" fashion. For
// example, instead of "sort.Slice(someSlice, ...)" a user can expand
// "someSlice.sort!".

// postfixTmpl represents a postfix snippet completion candidate.
type postfixTmpl struct {
	// label is the completion candidate's label presented to the user.
	label string

	// details is passed along to the client as the candidate's details.
	details string

	// body is the template text. See postfixTmplArgs for details on the
	// facilities available to the template.
	body string

	tmpl *template.Template
}

// postfixTmplArgs are the template execution arguments available to
// the postfix snippet templates.
type postfixTmplArgs struct {
	// StmtOK is true if it is valid to replace the selector with a
	// statement. For example:
	//
	//    func foo() {
	//      bar.sort! // statement okay
	//
	//      someMethod(bar.sort!) // statement not okay
	//    }
	StmtOK bool

	// X is the textual SelectorExpr.X. For example, when completing
	// "foo.bar.print!", "X" is "foo.bar".
	X string

	// Obj is the types.Object of SelectorExpr.X, if any.
	Obj types.Object

	// Type is the type of "foo.bar" in "foo.bar.print!".
	Type types.Type

	// FuncResults are results of the enclosed function
	FuncResults []*types.Var

	sel            *ast.SelectorExpr
	scope          *types.Scope
	snip           snippet.Builder
	importIfNeeded func(pkgPath string, scope *types.Scope) (name string, edits []protocol.TextEdit, err error)
	edits          []protocol.TextEdit
	qual           types.Qualifier
	varNames       map[string]bool
	placeholders   bool
	currentTabStop int
}

var postfixTmpls = []postfixTmpl{{
	label:   "sort",
	details: "sort.Slice()",
	body: `{{if and (eq .Kind "slice") .StmtOK -}}
{{.Import "sort"}}.Slice({{.X}}, func({{.VarName nil "i"}}, {{.VarName nil "j"}} int) bool {
	{{.Cursor}}
})
{{- end}}`,
}, {
	label:   "last",
	details: "s[len(s)-1]",
	body: `{{if and (eq .Kind "slice") .Obj -}}
{{.X}}[len({{.X}})-1]
{{- end}}`,
}, {
	label:   "reverse",
	details: "reverse slice",
	body: `{{if and (eq .Kind "slice") .StmtOK -}}
{{.Import "slices"}}.Reverse({{.X}})
{{- end}}`,
}, {
	label:   "range",
	details: "range over slice",
	body: `{{if and (eq .Kind "slice") .StmtOK -}}
for {{.VarName nil "i" | .Placeholder }}, {{.VarName .ElemType "v" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "for",
	details: "range over slice by index",
	body: `{{if and (eq .Kind "slice") .StmtOK -}}
for {{ .VarName nil "i" | .Placeholder }} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "forr",
	details: "range over slice by index and value",
	body: `{{if and (eq .Kind "slice") .StmtOK -}}
for {{.VarName nil "i" | .Placeholder }}, {{.VarName .ElemType "v" | .Placeholder }} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "append",
	details: "append and re-assign slice",
	body: `{{if and (eq .Kind "slice") .StmtOK .Obj -}}
{{.X}} = append({{.X}}, {{.Cursor}})
{{- end}}`,
}, {
	label:   "append",
	details: "append to slice",
	body: `{{if and (eq .Kind "slice") (not .StmtOK) -}}
append({{.X}}, {{.Cursor}})
{{- end}}`,
}, {
	label:   "copy",
	details: "duplicate slice",
	body: `{{if and (eq .Kind "slice") .StmtOK .Obj -}}
{{$v := (.VarName nil (printf "%sCopy" .X))}}{{$v}} := make([]{{.TypeName .ElemType}}, len({{.X}}))
copy({{$v}}, {{.X}})
{{end}}`,
}, {
	label:   "range",
	details: "range over map",
	body: `{{if and (eq .Kind "map") .StmtOK -}}
for {{.VarName .KeyType "k" | .Placeholder}}, {{.VarName .ElemType "v" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "for",
	details: "range over map by key",
	body: `{{if and (eq .Kind "map") .StmtOK -}}
for {{.VarName .KeyType "k" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "forr",
	details: "range over map by key and value",
	body: `{{if and (eq .Kind "map") .StmtOK -}}
for {{.VarName .KeyType "k" | .Placeholder}}, {{.VarName .ElemType "v" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "clear",
	details: "clear map contents",
	body: `{{if and (eq .Kind "map") .StmtOK -}}
{{$k := (.VarName .KeyType "k")}}for {{$k}} := range {{.X}} {
	delete({{.X}}, {{$k}})
}
{{end}}`,
}, {
	label:   "keys",
	details: "create slice of keys",
	body: `{{if and (eq .Kind "map") .StmtOK -}}
{{$keysVar := (.VarName nil "keys")}}{{$keysVar}} := make([]{{.TypeName .KeyType}}, 0, len({{.X}}))
{{$k := (.VarName .KeyType "k")}}for {{$k}} := range {{.X}} {
	{{$keysVar}} = append({{$keysVar}}, {{$k}})
}
{{end}}`,
}, {
	label:   "range",
	details: "range over channel",
	body: `{{if and (eq .Kind "chan") .StmtOK -}}
for {{.VarName .ElemType "e" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "for",
	details: "range over channel",
	body: `{{if and (eq .Kind "chan") .StmtOK -}}
for {{.VarName .ElemType "e" | .Placeholder}} := range {{.X}} {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "var",
	details: "assign to variables",
	body: `{{if and (eq .Kind "tuple") .StmtOK -}}
{{$a := .}}{{range $i, $v := .Tuple}}{{if $i}}, {{end}}{{$a.VarName $v.Type $v.Name | $a.Placeholder }}{{end}} := {{.X}}
{{- end}}`,
}, {
	label:   "var",
	details: "assign to variable",
	body: `{{if and (ne .Kind "tuple") .StmtOK -}}
{{.VarName .Type "" | .Placeholder }} := {{.X}}
{{- end}}`,
}, {
	label:   "print",
	details: "print to stdout",
	body: `{{if and (ne .Kind "tuple") .StmtOK -}}
{{.Import "fmt"}}.Printf("{{.EscapeQuotes .X}}: %v\n", {{.X}})
{{- end}}`,
}, {
	label:   "print",
	details: "print to stdout",
	body: `{{if and (eq .Kind "tuple") .StmtOK -}}
{{.Import "fmt"}}.Println({{.X}})
{{- end}}`,
}, {
	label:   "split",
	details: "split string",
	body: `{{if (eq (.TypeName .Type) "string") -}}
{{.Import "strings"}}.Split({{.X}}, "{{.Cursor}}")
{{- end}}`,
}, {
	label:   "join",
	details: "join string slice",
	body: `{{if and (eq .Kind "slice") (eq (.TypeName .ElemType) "string") -}}
{{.Import "strings"}}.Join({{.X}}, "{{.Cursor}}")
{{- end}}`,
}, {
	label:   "ifnotnil",
	details: "if expr != nil",
	body: `{{if and (or (eq .Kind "pointer") (eq .Kind "chan") (eq .Kind "signature") (eq .Kind "interface") (eq .Kind "map") (eq .Kind "slice")) .StmtOK -}}
if {{.X}} != nil {
	{{.Cursor}}
}
{{- end}}`,
}, {
	label:   "len",
	details: "len(s)",
	body: `{{if (eq .Kind "slice" "map" "array" "chan") -}}
len({{.X}})
{{- end}}`,
}, {
	label:   "iferr",
	details: "check error and return",
	body: `{{if and .StmtOK (eq (.TypeName .Type) "error") -}}
{{- $errName := (or (and .IsIdent .X) "err") -}}
if {{if not .IsIdent}}err := {{.X}}; {{end}}{{$errName}} != nil {
	return {{$a := .}}{{range $i, $v := .FuncResults}}
		{{- if $i}}, {{end -}}
		{{- if eq ($a.TypeName $v.Type) "error" -}}
			{{$a.Placeholder $errName}}
		{{- else -}}
			{{$a.Zero $v.Type}}
		{{- end -}}
	{{end}}
}
{{end}}`,
}, {
	label:   "iferr",
	details: "check error and return",
	body: `{{if and .StmtOK (eq .Kind "tuple") (len .Tuple) (eq (.TypeName .TupleLast.Type) "error") -}}
{{- $a := . -}}
if {{range $i, $v := .Tuple}}{{if $i}}, {{end}}{{if and (eq ($a.TypeName $v.Type) "error") (eq (inc $i) (len $a.Tuple))}}err{{else}}_{{end}}{{end}} := {{.X -}}
; err != nil {
	return {{range $i, $v := .FuncResults}}
		{{- if $i}}, {{end -}}
		{{- if eq ($a.TypeName $v.Type) "error" -}}
			{{$a.Placeholder "err"}}
		{{- else -}}
			{{$a.Zero $v.Type}}
		{{- end -}}
	{{end}}
}
{{end}}`,
}, {
	// variferr snippets use nested placeholders, as described in
	// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#snippet_syntax,
	// so that users can wrap the returned error without modifying the error
	// variable name.
	label:   "variferr",
	details: "assign variables and check error",
	body: `{{if and .StmtOK (eq .Kind "tuple") (len .Tuple) (eq (.TypeName .TupleLast.Type) "error") -}}
{{- $a := . -}}
{{- $errName := "err" -}}
{{- range $i, $v := .Tuple -}}
	{{- if $i}}, {{end -}}
	{{- if and (eq ($a.TypeName $v.Type) "error") (eq (inc $i) (len $a.Tuple)) -}}
		{{$errName | $a.SpecifiedPlaceholder (len $a.Tuple)}}
	{{- else -}}
		{{$a.VarName $v.Type $v.Name | $a.Placeholder}}
	{{- end -}}
{{- end}} := {{.X}}
if {{$errName | $a.SpecifiedPlaceholder (len $a.Tuple)}} != nil {
	return {{range $i, $v := .FuncResults}}
		{{- if $i}}, {{end -}}
		{{- if eq ($a.TypeName $v.Type) "error" -}}
			{{$errName | $a.SpecifiedPlaceholder (len $a.Tuple) |
				$a.SpecifiedPlaceholder (inc (len $a.Tuple))}}
		{{- else -}}
			{{$a.Zero $v.Type}}
		{{- end -}}
	{{end}}
}
{{end}}`,
}, {
	label:   "variferr",
	details: "assign variables and check error",
	body: `{{if and .StmtOK (eq (.TypeName .Type) "error") -}}
{{- $a := . -}}
{{- $errName := .VarName nil "err" -}}
{{$errName | $a.SpecifiedPlaceholder 1}} := {{.X}}
if {{$errName | $a.SpecifiedPlaceholder 1}} != nil {
	return {{range $i, $v := .FuncResults}}
		{{- if $i}}, {{end -}}
		{{- if eq ($a.TypeName $v.Type) "error" -}}
			{{$errName | $a.SpecifiedPlaceholder 1 | $a.SpecifiedPlaceholder 2}}
		{{- else -}}
			{{$a.Zero $v.Type}}
		{{- end -}}
	{{end}}
}
{{end}}`,
},
	{
		label:   "tostring",
		details: "[]byte to string",
		body: `{{if (eq (.TypeName .Type) "[]byte") -}}
	string({{.X}})
	{{- end}}`,
	},
	{
		label:   "tostring",
		details: "int to string",
		body: `{{if (eq (.TypeName .Type) "int") -}}
		{{.Import "strconv"}}.Itoa({{.X}})
		{{- end}}`,
	},
	{
		label:   "tobytes",
		details: "string to []byte",
		body: `{{if (eq (.TypeName .Type) "string") -}}
	[]byte({{.X}})
	{{- end}}`,
	},
}

// Cursor indicates where the client's cursor should end up after the
// snippet is done.
func (a *postfixTmplArgs) Cursor() string {
	return "$0"
}

// Placeholder indicate a tab stop with the placeholder string, the order
// of tab stops is the same as the order of invocation
func (a *postfixTmplArgs) Placeholder(placeholder string) string {
	if !a.placeholders {
		placeholder = ""
	}
	return fmt.Sprintf("${%d:%s}", a.nextTabStop(), placeholder)
}

// nextTabStop returns the next tab stop index for a new placeholder.
func (a *postfixTmplArgs) nextTabStop() int {
	// Tab stops start from 1, so increment before returning.
	a.currentTabStop++
	return a.currentTabStop
}

// SpecifiedPlaceholder indicate a specified tab stop with the placeholder string.
// Sometimes the same tab stop appears in multiple places and their numbers
// need to be specified. e.g. variferr
func (a *postfixTmplArgs) SpecifiedPlaceholder(tabStop int, placeholder string) string {
	if !a.placeholders {
		placeholder = ""
	}
	return fmt.Sprintf("${%d:%s}", tabStop, placeholder)
}

// Import makes sure the package corresponding to path is imported,
// returning the identifier to use to refer to the package.
func (a *postfixTmplArgs) Import(path string) (string, error) {
	name, edits, err := a.importIfNeeded(path, a.scope)
	if err != nil {
		return "", fmt.Errorf("couldn't import %q: %w", path, err)
	}
	a.edits = append(a.edits, edits...)

	return name, nil
}

func (a *postfixTmplArgs) EscapeQuotes(v string) string {
	return strings.ReplaceAll(v, `"`, `\\"`)
}

// ElemType returns the Elem() type of xType, if applicable.
func (a *postfixTmplArgs) ElemType() types.Type {
	type hasElem interface{ Elem() types.Type } // Array, Chan, Map, Pointer, Slice
	if e, ok := a.Type.Underlying().(hasElem); ok {
		return e.Elem()
	}
	return nil
}

// Kind returns the underlying kind of type, e.g. "slice", "struct",
// etc.
func (a *postfixTmplArgs) Kind() string {
	t := reflect.TypeOf(a.Type.Underlying())
	return strings.ToLower(strings.TrimPrefix(t.String(), "*types."))
}

// KeyType returns the type of X's key. KeyType panics if X is not a
// map.
func (a *postfixTmplArgs) KeyType() types.Type {
	return a.Type.Underlying().(*types.Map).Key()
}

// Tuple returns the tuple result vars if the type of X is tuple.
func (a *postfixTmplArgs) Tuple() []*types.Var {
	tuple, _ := a.Type.(*types.Tuple)
	typs := make([]*types.Var, tuple.Len())
	for i := range typs {
		typs[i] = tuple.At(i)
	}
	return typs
}

// TupleLast returns the last tuple result vars if the type of X is tuple.
func (a *postfixTmplArgs) TupleLast() *types.Var {
	tuple, _ := a.Type.(*types.Tuple)
	if tuple.Len() == 0 {
		return nil
	}
	return tuple.At(tuple.Len() - 1)
}

// TypeName returns the textual representation of type t.
func (a *postfixTmplArgs) TypeName(t types.Type) (string, error) {
	if t == nil || t == types.Typ[types.Invalid] {
		return "", fmt.Errorf("invalid type: %v", t)
	}
	return types.TypeString(t, a.qual), nil
}

// Zero return the zero value representation of type t
func (a *postfixTmplArgs) Zero(t types.Type) string {
	zero, _ := typesinternal.ZeroString(t, a.qual)
	return zero
}

func (a *postfixTmplArgs) IsIdent() bool {
	_, ok := a.sel.X.(*ast.Ident)
	return ok
}

// VarName returns a suitable variable name for the type t. If t
// implements the error interface, "err" is used. If t is not a named
// type then nonNamedDefault is used. Otherwise a name is made by
// abbreviating the type name. If the resultant name is already in
// scope, an integer is appended to make a unique name.
func (a *postfixTmplArgs) VarName(t types.Type, nonNamedDefault string) string {
	if t == nil {
		t = types.Typ[types.Invalid]
	}

	var name string
	// go/types predicates are undefined on types.Typ[types.Invalid].
	if !types.Identical(t, types.Typ[types.Invalid]) && types.Implements(t, errorIntf) {
		name = "err"
	} else if !is[*types.Named](types.Unalias(typesinternal.Unpointer(t))) {
		name = nonNamedDefault
	}

	if name == "" {
		name = types.TypeString(t, func(p *types.Package) string {
			return ""
		})
		name = abbreviateTypeName(name)
	}

	if dot := strings.LastIndex(name, "."); dot > -1 {
		name = name[dot+1:]
	}

	uniqueName := name
	for i := 2; ; i++ {
		if s, _ := a.scope.LookupParent(uniqueName, token.NoPos); s == nil && !a.varNames[uniqueName] {
			break
		}
		uniqueName = fmt.Sprintf("%s%d", name, i)
	}

	a.varNames[uniqueName] = true

	return uniqueName
}

func (c *completer) addPostfixSnippetCandidates(ctx context.Context, sel *ast.SelectorExpr) {
	if !c.opts.postfix {
		return
	}

	initPostfixRules()

	if sel == nil || sel.Sel == nil {
		return
	}

	selType := c.pkg.TypesInfo().TypeOf(sel.X)
	if selType == nil {
		return
	}

	// Skip empty tuples since there is no value to operate on.
	if tuple, ok := selType.(*types.Tuple); ok && tuple == nil {
		return
	}

	tokFile := c.pkg.FileSet().File(c.pos)

	// Only replace sel with a statement if sel is already a statement.
	var stmtOK bool
	for i, n := range c.path {
		if n == sel && i < len(c.path)-1 {
			switch p := c.path[i+1].(type) {
			case *ast.ExprStmt:
				stmtOK = true
			case *ast.AssignStmt:
				// In cases like:
				//
				//   foo.<>
				//   bar = 123
				//
				// detect that "foo." makes up the entire statement since the
				// apparent selector spans lines.
				stmtOK = safetoken.Line(tokFile, c.pos) < safetoken.Line(tokFile, p.TokPos)
			}
			break
		}
	}

	var funcResults []*types.Var
	if c.enclosingFunc != nil {
		results := c.enclosingFunc.sig.Results()
		if results != nil {
			funcResults = make([]*types.Var, results.Len())
			for i := range results.Len() {
				funcResults[i] = results.At(i)
			}
		}
	}

	scope := c.pkg.Types().Scope().Innermost(c.pos)
	if scope == nil {
		return
	}

	// afterDot is the position after selector dot, e.g. "|" in
	// "foo.|print".
	afterDot := sel.Sel.Pos()

	// We must detect dangling selectors such as:
	//
	//    foo.<>
	//    bar
	//
	// and adjust afterDot so that we don't mistakenly delete the
	// newline thinking "bar" is part of our selector.
	if startLine := safetoken.Line(tokFile, sel.Pos()); startLine != safetoken.Line(tokFile, afterDot) {
		if safetoken.Line(tokFile, c.pos) != startLine {
			return
		}
		afterDot = c.pos
	}

	for _, rule := range postfixTmpls {
		// When completing foo.print<>, "print" is naturally overwritten,
		// but we need to also remove "foo." so the snippet has a clean
		// slate.
		edits, err := c.editText(sel.Pos(), afterDot, "")
		if err != nil {
			event.Error(ctx, "error calculating postfix edits", err)
			return
		}

		tmplArgs := postfixTmplArgs{
			X:              golang.FormatNode(c.pkg.FileSet(), sel.X),
			StmtOK:         stmtOK,
			Obj:            exprObj(c.pkg.TypesInfo(), sel.X),
			Type:           selType,
			FuncResults:    funcResults,
			sel:            sel,
			qual:           c.qual,
			importIfNeeded: c.importIfNeeded,
			scope:          scope,
			varNames:       make(map[string]bool),
			placeholders:   c.opts.placeholders,
		}

		// Feed the template straight into the snippet builder. This
		// allows templates to build snippets as they are executed.
		err = rule.tmpl.Execute(&tmplArgs.snip, &tmplArgs)
		if err != nil {
			event.Error(ctx, "error executing postfix template", err)
			continue
		}

		if strings.TrimSpace(tmplArgs.snip.String()) == "" {
			continue
		}

		score := c.matcher.Score(rule.label)
		if score <= 0 {
			continue
		}

		c.items = append(c.items, CompletionItem{
			Label:               rule.label + "!",
			Detail:              rule.details,
			Score:               float64(score) * 0.01,
			Kind:                protocol.SnippetCompletion,
			snippet:             &tmplArgs.snip,
			AdditionalTextEdits: append(edits, tmplArgs.edits...),
		})
	}
}

var postfixRulesOnce sync.Once

func initPostfixRules() {
	postfixRulesOnce.Do(func() {
		var idx int
		for _, rule := range postfixTmpls {
			var err error
			rule.tmpl, err = template.New("postfix_snippet").Funcs(template.FuncMap{
				"inc": inc,
			}).Parse(rule.body)
			if err != nil {
				log.Panicf("error parsing postfix snippet template: %v", err)
			}
			postfixTmpls[idx] = rule
			idx++
		}
		postfixTmpls = postfixTmpls[:idx]
	})
}

func inc(i int) int {
	return i + 1
}

// importIfNeeded returns the package identifier and any necessary
// edits to import package pkgPath.
func (c *completer) importIfNeeded(pkgPath string, scope *types.Scope) (string, []protocol.TextEdit, error) {
	defaultName := imports.ImportPathToAssumedName(pkgPath)

	// Check if file already imports pkgPath.
	for _, s := range c.pgf.File.Imports {
		// TODO(adonovan): what if pkgPath has a vendor/ suffix?
		// This may be the cause of go.dev/issue/56291.
		if string(metadata.UnquoteImportPath(s)) == pkgPath {
			if s.Name == nil {
				return defaultName, nil, nil
			}
			if s.Name.Name != "_" {
				return s.Name.Name, nil, nil
			}
		}
	}

	// Give up if the package's name is already in use by another object.
	if _, obj := scope.LookupParent(defaultName, token.NoPos); obj != nil {
		return "", nil, fmt.Errorf("import name %q of %q already in use", defaultName, pkgPath)
	}

	edits, err := c.importEdits(&importInfo{
		importPath: pkgPath,
	})
	if err != nil {
		return "", nil, err
	}

	return defaultName, edits, nil
}


================================================
FILE: gopls/internal/golang/completion/printf.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"
	"go/constant"
	"go/types"
	"strconv"
	"strings"
	"unicode/utf8"
)

// printfArgKind returns the expected objKind when completing a
// printf-like operand. call is the printf-like function call, and
// argIdx is the index of call.Args being completed.
func printfArgKind(info *types.Info, call *ast.CallExpr, argIdx int) objKind {
	// Printf-like function name must end in "f".
	fn := exprObj(info, call.Fun)
	if fn == nil || !strings.HasSuffix(fn.Name(), "f") {
		return kindAny
	}

	sig, _ := fn.Type().Underlying().(*types.Signature)
	if sig == nil {
		return kindAny
	}

	// Must be variadic and take at least two params.
	numParams := sig.Params().Len()
	if !sig.Variadic() || numParams < 2 || argIdx < numParams-1 {
		return kindAny
	}

	// Param preceding variadic args must be a (format) string.
	if !types.Identical(sig.Params().At(numParams-2).Type(), types.Typ[types.String]) {
		return kindAny
	}

	// Format string must be a constant.
	strArg := info.Types[call.Args[numParams-2]].Value // may be zero
	if strArg == nil || strArg.Kind() != constant.String {
		return kindAny
	}

	return formatOperandKind(constant.StringVal(strArg), argIdx-(numParams-1)+1)
}

// formatOperandKind returns the objKind corresponding to format's
// operandIdx'th operand.
func formatOperandKind(format string, operandIdx int) objKind {
	var (
		prevOperandIdx int
		kind           = kindAny
	)
	for {
		i := strings.Index(format, "%")
		if i == -1 {
			break
		}

		var operands []formatOperand
		format, operands = parsePrintfVerb(format[i+1:], prevOperandIdx)

		// Check if any this verb's operands correspond to our target
		// operandIdx.
		for _, v := range operands {
			if v.idx == operandIdx {
				if kind == kindAny {
					kind = v.kind
				} else if v.kind != kindAny {
					// If multiple verbs refer to the same operand, take the
					// intersection of their kinds.
					kind &= v.kind
				}
			}

			prevOperandIdx = v.idx
		}
	}
	return kind
}

type formatOperand struct {
	// idx is the one-based printf operand index.
	idx int
	// kind is a mask of expected kinds of objects for this operand.
	kind objKind
}

// parsePrintfVerb parses the leading printf verb in f. The opening
// "%" must already be trimmed from f. prevIdx is the previous
// operand's index, or zero if this is the first verb. The format
// string is returned with the leading verb removed. Multiple operands
// can be returned in the case of dynamic widths such as "%*.*f".
func parsePrintfVerb(f string, prevIdx int) (string, []formatOperand) {
	var verbs []formatOperand

	addVerb := func(k objKind) {
		verbs = append(verbs, formatOperand{
			idx:  prevIdx + 1,
			kind: k,
		})
		prevIdx++
	}

	for len(f) > 0 {
		// Trim first rune off of f so we are guaranteed to make progress.
		r, l := utf8.DecodeRuneInString(f)
		f = f[l:]

		// We care about three things:
		// 1. The verb, which maps directly to object kind.
		// 2. Explicit operand indices like "%[2]s".
		// 3. Dynamic widths using "*".
		switch r {
		case '%':
			return f, nil
		case '*':
			addVerb(kindInt)
			continue
		case '[':
			// Parse operand index as in "%[2]s".
			i := strings.Index(f, "]")
			if i == -1 {
				return f, nil
			}

			idx, err := strconv.Atoi(f[:i])
			f = f[i+1:]
			if err != nil {
				return f, nil
			}

			prevIdx = idx - 1
			continue
		case 'v', 'T':
			addVerb(kindAny)
		case 't':
			addVerb(kindBool)
		case 'c', 'd', 'o', 'O', 'U':
			addVerb(kindInt)
		case 'e', 'E', 'f', 'F', 'g', 'G':
			addVerb(kindFloat | kindComplex)
		case 'b':
			addVerb(kindInt | kindFloat | kindComplex | kindBytes)
		case 'q', 's':
			addVerb(kindString | kindBytes | kindStringer | kindError)
		case 'x', 'X':
			// Omit kindStringer and kindError though technically allowed.
			addVerb(kindString | kindBytes | kindInt | kindFloat | kindComplex)
		case 'p':
			// Accept kindInterface even though it doesn't necessarily contain a pointer.
			// This avoids us offering "&foo" when "foo" is an interface type.
			addVerb(kindPtr | kindSlice | kindMap | kindFunc | kindInterface)
		case 'w':
			addVerb(kindError)
		case '+', '-', '#', ' ', '.', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			// Flag or numeric width/precision value.
			continue
		default:
			// Assume unrecognized rune is a custom fmt.Formatter verb.
			addVerb(kindAny)
		}

		if len(verbs) > 0 {
			break
		}
	}

	return f, verbs
}


================================================
FILE: gopls/internal/golang/completion/printf_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"fmt"
	"testing"
)

func TestFormatOperandKind(t *testing.T) {
	cases := []struct {
		f    string
		idx  int
		kind objKind
	}{
		{"", 1, kindAny},
		{"%", 1, kindAny},
		{"%%%", 1, kindAny},
		{"%[1", 1, kindAny},
		{"%[?%s", 2, kindAny},
		{"%[abc]v", 1, kindAny},

		{"%v", 1, kindAny},
		{"%T", 1, kindAny},
		{"%t", 1, kindBool},
		{"%d", 1, kindInt},
		{"%c", 1, kindInt},
		{"%o", 1, kindInt},
		{"%O", 1, kindInt},
		{"%U", 1, kindInt},
		{"%e", 1, kindFloat | kindComplex},
		{"%E", 1, kindFloat | kindComplex},
		{"%f", 1, kindFloat | kindComplex},
		{"%F", 1, kindFloat | kindComplex},
		{"%g", 1, kindFloat | kindComplex},
		{"%G", 1, kindFloat | kindComplex},
		{"%b", 1, kindInt | kindFloat | kindComplex | kindBytes},
		{"%q", 1, kindString | kindBytes | kindStringer | kindError},
		{"%s", 1, kindString | kindBytes | kindStringer | kindError},
		{"%x", 1, kindString | kindBytes | kindInt | kindFloat | kindComplex},
		{"%X", 1, kindString | kindBytes | kindInt | kindFloat | kindComplex},
		{"%p", 1, kindPtr | kindSlice | kindMap | kindFunc | kindInterface},
		{"%w", 1, kindError},

		{"%1.2f", 1, kindFloat | kindComplex},
		{"%*f", 1, kindInt},
		{"%*f", 2, kindFloat | kindComplex},
		{"%*.*f", 1, kindInt},
		{"%*.*f", 2, kindInt},
		{"%*.*f", 3, kindFloat | kindComplex},
		{"%[3]*.[2]*[1]f", 1, kindFloat | kindComplex},
		{"%[3]*.[2]*[1]f", 2, kindInt},
		{"%[3]*.[2]*[1]f", 3, kindInt},

		{"foo %% %d", 1, kindInt},
		{"%#-12.34f", 1, kindFloat | kindComplex},
		{"% d", 1, kindInt},

		{"%s %[1]X %d", 1, kindString | kindBytes},
		{"%s %[1]X %d", 2, kindInt},
	}

	for _, c := range cases {
		t.Run(fmt.Sprintf("%q#%d", c.f, c.idx), func(t *testing.T) {
			if got := formatOperandKind(c.f, c.idx); got != c.kind {
				t.Errorf("expected %d (%[1]b), got %d (%[2]b)", c.kind, got)
			}
		})
	}
}


================================================
FILE: gopls/internal/golang/completion/snippet/snippet_builder.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package snippet implements the specification for the LSP snippet format.
//
// Snippets are "tab stop" templates returned as an optional attribute of LSP
// completion candidates. As the user presses tab, they cycle through a series of
// tab stops defined in the snippet. Each tab stop can optionally have placeholder
// text, which can be pre-selected by editors. For a full description of syntax
// and features, see "Snippet Syntax" at
// https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_completion.
//
// A typical snippet looks like "foo(${1:i int}, ${2:s string})".
package snippet

import (
	"fmt"
	"strings"
)

// A Builder is used to build an LSP snippet piecemeal.
// The zero value is ready to use. Do not copy a non-zero Builder.
type Builder struct {
	// currentTabStop is the index of the previous tab stop. The
	// next tab stop will be currentTabStop+1.
	currentTabStop int
	sb             strings.Builder
}

// Escape characters defined in https://microsoft.github.io/language-server-protocol/specifications/specification-3-14/#textDocument_completion under "Grammar".
var replacer = strings.NewReplacer(
	`\`, `\\`,
	`}`, `\}`,
	`$`, `\$`,
)

func (b *Builder) WriteText(s string) {
	replacer.WriteString(&b.sb, s)
}

func (b *Builder) PrependText(s string) {
	rawSnip := b.String()
	b.sb.Reset()
	b.WriteText(s)
	b.sb.WriteString(rawSnip)
}

func (b *Builder) Write(data []byte) (int, error) {
	return b.sb.Write(data)
}

// WritePlaceholder writes a tab stop and placeholder value to the Builder.
// The callback style allows for creating nested placeholders. To write an
// empty tab stop, provide a nil callback.
func (b *Builder) WritePlaceholder(fn func(*Builder)) {
	fmt.Fprintf(&b.sb, "${%d:", b.nextTabStop())
	if fn != nil {
		fn(b)
	}
	b.sb.WriteByte('}')
}

// WriteFinalTabstop marks where cursor ends up after the user has
// cycled through all the normal tab stops. It defaults to the
// character after the snippet.
func (b *Builder) WriteFinalTabstop() {
	fmt.Fprint(&b.sb, "$0")
}

// In addition to '\', '}', and '$', snippet choices also use '|' and ',' as
// meta characters, so they must be escaped within the choices.
var choiceReplacer = strings.NewReplacer(
	`\`, `\\`,
	`}`, `\}`,
	`$`, `\$`,
	`|`, `\|`,
	`,`, `\,`,
)

// WriteChoice writes a tab stop and list of text choices to the Builder.
// The user's editor will prompt the user to choose one of the choices.
func (b *Builder) WriteChoice(choices []string) {
	fmt.Fprintf(&b.sb, "${%d|", b.nextTabStop())
	for i, c := range choices {
		if i != 0 {
			b.sb.WriteByte(',')
		}
		choiceReplacer.WriteString(&b.sb, c)
	}
	b.sb.WriteString("|}")
}

// String returns the built snippet string.
func (b *Builder) String() string {
	return b.sb.String()
}

// Clone returns a copy of b.
func (b *Builder) Clone() *Builder {
	var clone Builder
	clone.sb.WriteString(b.String())
	return &clone
}

// nextTabStop returns the next tab stop index for a new placeholder.
func (b *Builder) nextTabStop() int {
	// Tab stops start from 1, so increment before returning.
	b.currentTabStop++
	return b.currentTabStop
}


================================================
FILE: gopls/internal/golang/completion/snippet/snippet_builder_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package snippet

import (
	"testing"
)

func TestSnippetBuilder(t *testing.T) {
	expect := func(expected string, fn func(*Builder)) {
		t.Helper()

		var b Builder
		fn(&b)
		if got := b.String(); got != expected {
			t.Errorf("got %q, expected %q", got, expected)
		}
	}

	expect("", func(b *Builder) {})

	expect(`hi { \} \$ | " , / \\`, func(b *Builder) {
		b.WriteText(`hi { } $ | " , / \`)
	})

	expect("${1:}", func(b *Builder) {
		b.WritePlaceholder(nil)
	})

	expect("hi ${1:there}", func(b *Builder) {
		b.WriteText("hi ")
		b.WritePlaceholder(func(b *Builder) {
			b.WriteText("there")
		})
	})

	expect(`${1:id=${2:{your id\}}}`, func(b *Builder) {
		b.WritePlaceholder(func(b *Builder) {
			b.WriteText("id=")
			b.WritePlaceholder(func(b *Builder) {
				b.WriteText("{your id}")
			})
		})
	})

	expect(`${1|one,{ \} \$ \| " \, / \\,three|}`, func(b *Builder) {
		b.WriteChoice([]string{"one", `{ } $ | " , / \`, "three"})
	})

	expect("$0 hello", func(b *Builder) {
		b.WriteFinalTabstop()
		b.WriteText(" hello")
	})

	expect(`prepended \$5 ${1:} hello`, func(b *Builder) {
		b.WritePlaceholder(nil)
		b.WriteText(" hello")
		b.PrependText("prepended $5 ")
	})
}


================================================
FILE: gopls/internal/golang/completion/snippet.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"

	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// structFieldSnippet calculates the snippet for struct literal field names.
func (c *completer) structFieldSnippet(cand candidate, detail string, snip *snippet.Builder) {
	if !wantStructFieldCompletions(c.enclosingCompositeLiteral) {
		return
	}

	// If we are in a deep completion then we can't be completing a field
	// name (e.g. "Foo{f<>}" completing to "Foo{f.Bar}" should not generate
	// a snippet).
	if len(cand.path) > 0 {
		return
	}

	clInfo := c.enclosingCompositeLiteral

	// If we are already in a key-value expression, we don't want a snippet.
	if clInfo.kv != nil {
		return
	}

	// A plain snippet turns "Foo{Ba<>" into "Foo{Bar: <>".
	snip.WriteText(": ")
	snip.WritePlaceholder(func(b *snippet.Builder) {
		// A placeholder snippet turns "Foo{Ba<>" into "Foo{Bar: <*int*>".
		if c.opts.placeholders {
			b.WriteText(detail)
		}
	})

	fset := c.pkg.FileSet()

	// If the cursor position is on a different line from the literal's opening brace,
	// we are in a multiline literal. Ignore line directives.
	if safetoken.StartPosition(fset, c.pos).Line != safetoken.StartPosition(fset, clInfo.cl.Lbrace).Line {
		snip.WriteText(",")
	}
}

// functionCallSnippet calculates the snippet for function calls.
//
// Callers should omit the suffix of type parameters that are
// constrained by the argument types, to avoid offering completions
// that contain instantiations that are redundant because of type
// inference, such as f[int](1) for func f[T any](x T).
func (c *completer) functionCallSnippet(name string, tparams, params []string, snip *snippet.Builder) {
	if !c.opts.completeFunctionCalls {
		snip.WriteText(name)
		return
	}

	// If there is no suffix then we need to reuse existing call parens
	// "()" if present. If there is an identifier suffix then we always
	// need to include "()" since we don't overwrite the suffix.
	if c.surrounding != nil && c.surrounding.Suffix() == "" && len(c.path) > 1 {
		// If we are the left side (i.e. "Fun") part of a call expression,
		// we don't want a snippet since there are already parens present.
		switch n := c.path[1].(type) {
		case *ast.CallExpr:
			// The Lparen != Rparen check detects fudged CallExprs we
			// inserted when fixing the AST. In this case, we do still need
			// to insert the calling "()" parens.
			if n.Fun == c.path[0] && n.Lparen != n.Rparen {
				return
			}
		case *ast.SelectorExpr:
			if len(c.path) > 2 {
				if call, ok := c.path[2].(*ast.CallExpr); ok && call.Fun == c.path[1] && call.Lparen != call.Rparen {
					return
				}
			}
		}
	}

	snip.WriteText(name)

	if len(tparams) > 0 {
		snip.WriteText("[")
		if c.opts.placeholders {
			for i, tp := range tparams {
				if i > 0 {
					snip.WriteText(", ")
				}
				snip.WritePlaceholder(func(b *snippet.Builder) {
					b.WriteText(tp)
				})
			}
		} else {
			snip.WritePlaceholder(nil)
		}
		snip.WriteText("]")
	}

	snip.WriteText("(")

	if c.opts.placeholders {
		// A placeholder snippet turns "someFun<>" into "someFunc(<*i int*>, *s string*)".
		for i, p := range params {
			if i > 0 {
				snip.WriteText(", ")
			}
			snip.WritePlaceholder(func(b *snippet.Builder) {
				b.WriteText(p)
			})
		}
	} else {
		// A plain snippet turns "someFun<>" into "someFunc(<>)".
		if len(params) > 0 {
			snip.WritePlaceholder(nil)
		}
	}

	snip.WriteText(")")
}


================================================
FILE: gopls/internal/golang/completion/statements.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/typesinternal"
)

// addStatementCandidates adds full statement completion candidates
// appropriate for the current context.
func (c *completer) addStatementCandidates() {
	c.addErrCheck()
	c.addAssignAppend()
	c.addReturnZeroValues()
}

// addAssignAppend offers a completion candidate of the form:
//
//	someSlice = append(someSlice, )
//
// It will offer the "append" completion in either of two situations:
//
//  1. Position is in RHS of assign, prefix matches "append", and
//     corresponding LHS object is a slice. For example,
//     "foo = ap<>" completes to "foo = append(foo, )".
//
//  2. Prefix is an ident or selector in an *ast.ExprStmt (i.e.
//     beginning of statement), and our best matching candidate is a
//     slice. For example: "foo.ba" completes to "foo.bar = append(foo.bar, )".
func (c *completer) addAssignAppend() {
	if len(c.path) < 3 {
		return
	}

	ident, _ := c.path[0].(*ast.Ident)
	if ident == nil {
		return
	}

	var (
		// sliceText is the full name of our slice object, e.g. "s.abc" in
		// "s.abc = app<>".
		sliceText string
		// needsLHS is true if we need to prepend the LHS slice name and
		// "=" to our candidate.
		needsLHS = false
		fset     = c.pkg.FileSet()
	)

	switch n := c.path[1].(type) {
	case *ast.AssignStmt:
		// We are already in an assignment. Make sure our prefix matches "append".
		if c.matcher.Score("append") <= 0 {
			return
		}

		exprIdx := exprAtPos(c.pos, n.Rhs)
		if exprIdx == len(n.Rhs) || exprIdx > len(n.Lhs)-1 {
			return
		}

		lhsType := c.pkg.TypesInfo().TypeOf(n.Lhs[exprIdx])
		if lhsType == nil {
			return
		}

		// Make sure our corresponding LHS object is a slice.
		if _, isSlice := lhsType.Underlying().(*types.Slice); !isSlice {
			return
		}

		// The name or our slice is whatever's in the LHS expression.
		sliceText = golang.FormatNode(fset, n.Lhs[exprIdx])
	case *ast.SelectorExpr:
		// Make sure we are a selector at the beginning of a statement.
		if _, parentIsExprtStmt := c.path[2].(*ast.ExprStmt); !parentIsExprtStmt {
			return
		}

		// So far we only know the first part of our slice name. For
		// example in "s.a<>" we only know our slice begins with "s."
		// since the user could still be typing.
		sliceText = golang.FormatNode(fset, n.X) + "."
		needsLHS = true
	case *ast.ExprStmt:
		needsLHS = true
	default:
		return
	}

	var (
		label string
		snip  snippet.Builder
		score = highScore
	)

	if needsLHS {
		// Offer the long form assign + append candidate if our best
		// candidate is a slice.
		bestItem := c.topCandidate()
		if bestItem == nil || !bestItem.isSlice {
			return
		}

		// Don't rank the full form assign + append candidate above the
		// slice itself.
		score = bestItem.Score - 0.01

		// Fill in rest of sliceText now that we have the object name.
		sliceText += bestItem.Label

		// Fill in the candidate's LHS bits.
		label = fmt.Sprintf("%s = ", bestItem.Label)
		snip.WriteText(label)
	}

	snip.WriteText(fmt.Sprintf("append(%s, ", sliceText))
	snip.WritePlaceholder(nil)
	snip.WriteText(")")

	c.items = append(c.items, CompletionItem{
		Label:   label + fmt.Sprintf("append(%s, )", sliceText),
		Kind:    protocol.FunctionCompletion,
		Score:   score,
		snippet: &snip,
	})
}

// topCandidate returns the strictly highest scoring candidate
// collected so far. If the top two candidates have the same score,
// nil is returned.
func (c *completer) topCandidate() *CompletionItem {
	var bestItem, secondBestItem *CompletionItem
	for i := range c.items {
		if bestItem == nil || c.items[i].Score > bestItem.Score {
			bestItem = &c.items[i]
		} else if secondBestItem == nil || c.items[i].Score > secondBestItem.Score {
			secondBestItem = &c.items[i]
		}
	}

	// If secondBestItem has the same score, bestItem isn't
	// the strict best.
	if secondBestItem != nil && secondBestItem.Score == bestItem.Score {
		return nil
	}

	return bestItem
}

// addErrCheck offers a completion candidate of the form:
//
//	if err != nil {
//	  return nil, err
//	}
//
// In the case of test functions, it offers a completion candidate of the form:
//
//	if err != nil {
//	  t.Fatal(err)
//	}
//
// The position must be in a function that returns an error, and the
// statement preceding the position must be an assignment where the
// final LHS object is an error. addErrCheck will synthesize
// zero values as necessary to make the return statement valid.
func (c *completer) addErrCheck() {
	if len(c.path) < 2 || c.enclosingFunc == nil || !c.opts.placeholders {
		return
	}

	var (
		errorType        = types.Universe.Lookup("error").Type()
		result           = c.enclosingFunc.sig.Results()
		testVar          = getTestVar(c.enclosingFunc, c.pkg)
		isTest           = testVar != ""
		doesNotReturnErr = result.Len() == 0 || !types.Identical(result.At(result.Len()-1).Type(), errorType)
	)
	// Make sure our enclosing function is a Test func or returns an error.
	if !isTest && doesNotReturnErr {
		return
	}

	prevLine := prevStmt(c.pos, c.path)
	if prevLine == nil {
		return
	}

	// Make sure our preceding statement was as assignment.
	assign, _ := prevLine.(*ast.AssignStmt)
	if assign == nil || len(assign.Lhs) == 0 {
		return
	}

	lastAssignee := assign.Lhs[len(assign.Lhs)-1]

	// Make sure the final assignee is an error.
	if !types.Identical(c.pkg.TypesInfo().TypeOf(lastAssignee), errorType) {
		return
	}

	var (
		// errVar is e.g. "err" in "foo, err := bar()".
		errVar = golang.FormatNode(c.pkg.FileSet(), lastAssignee)

		// Whether we need to include the "if" keyword in our candidate.
		needsIf = true
	)

	// If the returned error from the previous statement is "_", it is not a real object.
	// If we don't have an error, and the function signature takes a testing.TB that is either ignored
	// or an "_", then we also can't call t.Fatal(err).
	if errVar == "_" {
		return
	}

	// Below we try to detect if the user has already started typing "if
	// err" so we can replace what they've typed with our complete
	// statement.
	switch n := c.path[0].(type) {
	case *ast.Ident:
		switch c.path[1].(type) {
		case *ast.ExprStmt:
			// This handles:
			//
			//     f, err := os.Open("foo")
			//     i<>

			// Make sure they are typing "if".
			if c.matcher.Score("if") <= 0 {
				return
			}
		case *ast.IfStmt:
			// This handles:
			//
			//     f, err := os.Open("foo")
			//     if er<>

			// Make sure they are typing the error's name.
			if c.matcher.Score(errVar) <= 0 {
				return
			}

			needsIf = false
		default:
			return
		}
	case *ast.IfStmt:
		// This handles:
		//
		//     f, err := os.Open("foo")
		//     if <>

		// Avoid false positives by ensuring the if's cond is a bad
		// expression. For example, don't offer the completion in cases
		// like "if <> somethingElse".
		if _, bad := n.Cond.(*ast.BadExpr); !bad {
			return
		}

		// If "if" is our direct prefix, we need to include it in our
		// candidate since the existing "if" will be overwritten.
		needsIf = c.pos == n.Pos()+token.Pos(len("if"))
	}

	// Build up a snippet that looks like:
	//
	//     if err != nil {
	//       return <zero value>, ..., ${1:err}
	//     }
	//
	// We make the error a placeholder so it is easy to alter the error.
	var snip snippet.Builder
	if needsIf {
		snip.WriteText("if ")
	}
	snip.WriteText(fmt.Sprintf("%s != nil {\n\t", errVar))

	var label string
	if isTest {
		snip.WriteText(fmt.Sprintf("%s.Fatal(%s)", testVar, errVar))
		label = fmt.Sprintf("%[1]s != nil { %[2]s.Fatal(%[1]s) }", errVar, testVar)
	} else {
		snip.WriteText("return ")
		for i := range result.Len() - 1 {
			if zero, isValid := typesinternal.ZeroString(result.At(i).Type(), c.qual); isValid {
				snip.WriteText(zero)
			}
			snip.WriteText(", ")
		}
		snip.WritePlaceholder(func(b *snippet.Builder) {
			b.WriteText(errVar)
		})
		label = fmt.Sprintf("%[1]s != nil { return %[1]s }", errVar)
	}

	snip.WriteText("\n}")

	if needsIf {
		label = "if " + label
	}

	c.items = append(c.items, CompletionItem{
		Label:   label,
		Kind:    protocol.SnippetCompletion,
		Score:   highScore,
		snippet: &snip,
	})
}

// getTestVar checks the function signature's input parameters and returns
// the name of the first parameter that implements "testing.TB". For example,
// func someFunc(t *testing.T) returns the string "t", func someFunc(b *testing.B)
// returns "b" etc. An empty string indicates that the function signature
// does not take a testing.TB parameter or does so but is ignored such
// as func someFunc(*testing.T).
func getTestVar(enclosingFunc *funcInfo, pkg *cache.Package) string {
	if enclosingFunc == nil || enclosingFunc.sig == nil {
		return ""
	}

	var testingPkg *types.Package
	for _, p := range pkg.Types().Imports() {
		if p.Path() == "testing" {
			testingPkg = p
			break
		}
	}
	if testingPkg == nil {
		return ""
	}
	tbObj := testingPkg.Scope().Lookup("TB")
	if tbObj == nil {
		return ""
	}
	iface, ok := tbObj.Type().Underlying().(*types.Interface)
	if !ok {
		return ""
	}

	sig := enclosingFunc.sig
	for param := range sig.Params().Variables() {
		if param.Name() == "_" {
			continue
		}
		if !types.Implements(param.Type(), iface) {
			continue
		}
		return param.Name()
	}

	return ""
}

// addReturnZeroValues offers a snippet candidate on the form:
//
//	return 0, "", nil
//
// Requires a partially or fully written return keyword at position.
// Requires current position to be in a function with more than
// zero return parameters.
func (c *completer) addReturnZeroValues() {
	if len(c.path) < 2 || c.enclosingFunc == nil || !c.opts.placeholders {
		return
	}
	result := c.enclosingFunc.sig.Results()
	if result.Len() == 0 {
		return
	}

	// Offer just less than we expect from return as a keyword.
	var score = stdScore - 0.01
	switch c.path[0].(type) {
	case *ast.ReturnStmt, *ast.Ident:
		f := c.matcher.Score("return")
		if f <= 0 {
			return
		}
		score *= float64(f)
	default:
		return
	}

	// The snippet will have a placeholder over each return value.
	// The label will not.
	var snip snippet.Builder
	var label strings.Builder
	snip.WriteText("return ")
	fmt.Fprintf(&label, "return ")

	for i := range result.Len() {
		if i > 0 {
			snip.WriteText(", ")
			fmt.Fprintf(&label, ", ")
		}

		zero, isValid := typesinternal.ZeroString(result.At(i).Type(), c.qual)
		if !isValid {
			zero = ""
		}
		snip.WritePlaceholder(func(b *snippet.Builder) {
			b.WriteText(zero)
		})
		fmt.Fprint(&label, zero)
	}

	c.items = append(c.items, CompletionItem{
		Label:   label.String(),
		Kind:    protocol.SnippetCompletion,
		Score:   score,
		snippet: &snip,
	})
}


================================================
FILE: gopls/internal/golang/completion/unify.go
================================================
// Below was copied from go/types/unify.go on September 24, 2024,
// and combined with snippets from other files as well.
// It is copied to implement unification for code completion inferences,
// in lieu of an official type unification API.
//
// TODO: When such an API is available, the code below should deleted.
//
// Due to complexity of extracting private types from the go/types package,
// the unifier does not fully implement interface unification.
//
// The code has been modified to compile without introducing any key functionality changes.
//

// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements type unification.
//
// Type unification attempts to make two types x and y structurally
// equivalent by determining the types for a given list of (bound)
// type parameters which may occur within x and y. If x and y are
// structurally different (say []T vs chan T), or conflicting
// types are determined for type parameters, unification fails.
// If unification succeeds, as a side-effect, the types of the
// bound type parameters may be determined.
//
// Unification typically requires multiple calls u.unify(x, y) to
// a given unifier u, with various combinations of types x and y.
// In each call, additional type parameter types may be determined
// as a side effect and recorded in u.
// If a call fails (returns false), unification fails.
//
// In the unification context, structural equivalence of two types
// ignores the difference between a defined type and its underlying
// type if one type is a defined type and the other one is not.
// It also ignores the difference between an (external, unbound)
// type parameter and its core type.
// If two types are not structurally equivalent, they cannot be Go
// identical types. On the other hand, if they are structurally
// equivalent, they may be Go identical or at least assignable, or
// they may be in the type set of a constraint.
// Whether they indeed are identical or assignable is determined
// upon instantiation and function argument passing.

package completion

import (
	"fmt"
	"go/types"
	"strings"
)

const (
	// Upper limit for recursion depth. Used to catch infinite recursions
	// due to implementation issues (e.g., see issues go.dev/issue/48619, go.dev/issue/48656).
	unificationDepthLimit = 50

	// Whether to panic when unificationDepthLimit is reached.
	// If disabled, a recursion depth overflow results in a (quiet)
	// unification failure.
	panicAtUnificationDepthLimit = true

	// If enableCoreTypeUnification is set, unification will consider
	// the core types, if any, of non-local (unbound) type parameters.
	enableCoreTypeUnification = true
)

// A unifier maintains a list of type parameters and
// corresponding types inferred for each type parameter.
// A unifier is created by calling newUnifier.
type unifier struct {
	// handles maps each type parameter to its inferred type through
	// an indirection *Type called (inferred type) "handle".
	// Initially, each type parameter has its own, separate handle,
	// with a nil (i.e., not yet inferred) type.
	// After a type parameter P is unified with a type parameter Q,
	// P and Q share the same handle (and thus type). This ensures
	// that inferring the type for a given type parameter P will
	// automatically infer the same type for all other parameters
	// unified (joined) with P.
	handles map[*types.TypeParam]*types.Type
	depth   int // recursion depth during unification
}

// newUnifier returns a new unifier initialized with the given type parameter
// and corresponding type argument lists. The type argument list may be shorter
// than the type parameter list, and it may contain nil types. Matching type
// parameters and arguments must have the same index.
func newUnifier(tparams []*types.TypeParam, targs []types.Type) *unifier {
	handles := make(map[*types.TypeParam]*types.Type, len(tparams))
	// Allocate all handles up-front: in a correct program, all type parameters
	// must be resolved and thus eventually will get a handle.
	// Also, sharing of handles caused by unified type parameters is rare and
	// so it's ok to not optimize for that case (and delay handle allocation).
	for i, x := range tparams {
		var t types.Type
		if i < len(targs) {
			t = targs[i]
		}
		handles[x] = &t
	}
	return &unifier{handles, 0}
}

// unifyMode controls the behavior of the unifier.
type unifyMode uint

const (
	// If unifyModeAssign is set, we are unifying types involved in an assignment:
	// they may match inexactly at the top, but element types must match
	// exactly.
	unifyModeAssign unifyMode = 1 << iota

	// If unifyModeExact is set, types unify if they are identical (or can be
	// made identical with suitable arguments for type parameters).
	// Otherwise, a named type and a type literal unify if their
	// underlying types unify, channel directions are ignored, and
	// if there is an interface, the other type must implement the
	// interface.
	unifyModeExact
)

// This function was copied from go/types/unify.go
//
// unify attempts to unify x and y and reports whether it succeeded.
// As a side-effect, types may be inferred for type parameters.
// The mode parameter controls how types are compared.
func (u *unifier) unify(x, y types.Type, mode unifyMode) bool {
	return u.nify(x, y, mode)
}

// join unifies the given type parameters x and y.
// If both type parameters already have a type associated with them
// and they are not joined, join fails and returns false.
func (u *unifier) join(x, y *types.TypeParam) bool {
	switch hx, hy := u.handles[x], u.handles[y]; {
	case hx == hy:
		// Both type parameters already share the same handle. Nothing to do.
	case *hx != nil && *hy != nil:
		// Both type parameters have (possibly different) inferred types. Cannot join.
		return false
	case *hx != nil:
		// Only type parameter x has an inferred type. Use handle of x.
		u.setHandle(y, hx)
	// This case is treated like the default case.
	// case *hy != nil:
	// 	// Only type parameter y has an inferred type. Use handle of y.
	//	u.setHandle(x, hy)
	default:
		// Neither type parameter has an inferred type. Use handle of y.
		u.setHandle(x, hy)
	}
	return true
}

// asBoundTypeParam returns x.(*types.TypeParam) if x is a type parameter recorded with u.
// Otherwise, the result is nil.
func (u *unifier) asBoundTypeParam(x types.Type) *types.TypeParam {
	if x, _ := types.Unalias(x).(*types.TypeParam); x != nil {
		if _, found := u.handles[x]; found {
			return x
		}
	}
	return nil
}

// setHandle sets the handle for type parameter x
// (and all its joined type parameters) to h.
func (u *unifier) setHandle(x *types.TypeParam, h *types.Type) {
	hx := u.handles[x]
	for y, hy := range u.handles {
		if hy == hx {
			u.handles[y] = h
		}
	}
}

// at returns the (possibly nil) type for type parameter x.
func (u *unifier) at(x *types.TypeParam) types.Type {
	return *u.handles[x]
}

// set sets the type t for type parameter x;
// t must not be nil.
func (u *unifier) set(x *types.TypeParam, t types.Type) {
	*u.handles[x] = t
}

// asInterface returns the underlying type of x as an interface if
// it is a non-type parameter interface. Otherwise it returns nil.
func asInterface(x types.Type) (i *types.Interface) {
	if _, ok := types.Unalias(x).(*types.TypeParam); !ok {
		i, _ = x.Underlying().(*types.Interface)
	}
	return i
}

func isTypeParam(t types.Type) bool {
	_, ok := types.Unalias(t).(*types.TypeParam)
	return ok
}

func asNamed(t types.Type) *types.Named {
	n, _ := types.Unalias(t).(*types.Named)
	return n
}

func isTypeLit(t types.Type) bool {
	switch types.Unalias(t).(type) {
	case *types.Named, *types.TypeParam:
		return false
	}
	return true
}

// identicalOrigin reports whether x and y originated in the same declaration.
func identicalOrigin(x, y *types.Named) bool {
	// TODO(gri) is this correct?
	return x.Origin().Obj() == y.Origin().Obj()
}

func coreType(t types.Type) types.Type {
	t = types.Unalias(t)
	tpar, _ := t.(*types.TypeParam)
	if tpar == nil {
		return t.Underlying()
	}

	return nil
}

func sameId(obj *types.Var, pkg *types.Package, name string, foldCase bool) bool {
	// If we don't care about capitalization, we also ignore packages.
	if foldCase && strings.EqualFold(obj.Name(), name) {
		return true
	}
	// spec:
	// "Two identifiers are different if they are spelled differently,
	// or if they appear in different packages and are not exported.
	// Otherwise, they are the same."
	if obj.Name() != name {
		return false
	}
	// obj.Name == name
	if obj.Exported() {
		return true
	}
	// not exported, so packages must be the same
	if obj.Pkg() != nil && pkg != nil {
		return obj.Pkg() == pkg
	}
	return obj.Pkg().Path() == pkg.Path()
}

// nify implements the core unification algorithm which is an
// adapted version of Checker.identical. For changes to that
// code the corresponding changes should be made here.
// Must not be called directly from outside the unifier.
func (u *unifier) nify(x, y types.Type, mode unifyMode) (result bool) {
	u.depth++
	defer func() {
		u.depth--
	}()

	// nothing to do if x == y
	if x == y || types.Unalias(x) == types.Unalias(y) {
		return true
	}

	// Stop gap for cases where unification fails.
	if u.depth > unificationDepthLimit {
		if panicAtUnificationDepthLimit {
			panic("unification reached recursion depth limit")
		}
		return false
	}

	// Unification is symmetric, so we can swap the operands.
	// Ensure that if we have at least one
	// - defined type, make sure one is in y
	// - type parameter recorded with u, make sure one is in x
	if asNamed(x) != nil || u.asBoundTypeParam(y) != nil {
		x, y = y, x
	}

	// Unification will fail if we match a defined type against a type literal.
	// If we are matching types in an assignment, at the top-level, types with
	// the same type structure are permitted as long as at least one of them
	// is not a defined type. To accommodate for that possibility, we continue
	// unification with the underlying type of a defined type if the other type
	// is a type literal. This is controlled by the exact unification mode.
	// We also continue if the other type is a basic type because basic types
	// are valid underlying types and may appear as core types of type constraints.
	// If we exclude them, inferred defined types for type parameters may not
	// match against the core types of their constraints (even though they might
	// correctly match against some of the types in the constraint's type set).
	// Finally, if unification (incorrectly) succeeds by matching the underlying
	// type of a defined type against a basic type (because we include basic types
	// as type literals here), and if that leads to an incorrectly inferred type,
	// we will fail at function instantiation or argument assignment time.
	//
	// If we have at least one defined type, there is one in y.
	if ny := asNamed(y); mode&unifyModeExact == 0 && ny != nil && isTypeLit(x) {
		y = ny.Underlying()
		// Per the spec, a defined type cannot have an underlying type
		// that is a type parameter.
		// x and y may be identical now
		if x == y || types.Unalias(x) == types.Unalias(y) {
			return true
		}
	}

	// Cases where at least one of x or y is a type parameter recorded with u.
	// If we have at least one type parameter, there is one in x.
	// If we have exactly one type parameter, because it is in x,
	// isTypeLit(x) is false and y was not changed above. In other
	// words, if y was a defined type, it is still a defined type
	// (relevant for the logic below).
	switch px, py := u.asBoundTypeParam(x), u.asBoundTypeParam(y); {
	case px != nil && py != nil:
		// both x and y are type parameters
		if u.join(px, py) {
			return true
		}
		// both x and y have an inferred type - they must match
		return u.nify(u.at(px), u.at(py), mode)

	case px != nil:
		// x is a type parameter, y is not
		if x := u.at(px); x != nil {
			// x has an inferred type which must match y
			if u.nify(x, y, mode) {
				// We have a match, possibly through underlying types.
				xi := asInterface(x)
				yi := asInterface(y)
				xn := asNamed(x) != nil
				yn := asNamed(y) != nil
				// If we have two interfaces, what to do depends on
				// whether they are named and their method sets.
				if xi != nil && yi != nil {
					// Both types are interfaces.
					// If both types are defined types, they must be identical
					// because unification doesn't know which type has the "right" name.
					if xn && yn {
						return types.Identical(x, y)
					}
					return false
					// Below is the original code for reference

					// In all other cases, the method sets must match.
					// The types unified so we know that corresponding methods
					// match and we can simply compare the number of methods.
					// TODO(gri) We may be able to relax this rule and select
					// the more general interface. But if one of them is a defined
					// type, it's not clear how to choose and whether we introduce
					// an order dependency or not. Requiring the same method set
					// is conservative.
					// if len(xi.typeSet().methods) != len(yi.typeSet().methods) {
					// 	return false
					// }
				} else if xi != nil || yi != nil {
					// One but not both of them are interfaces.
					// In this case, either x or y could be viable matches for the corresponding
					// type parameter, which means choosing either introduces an order dependence.
					// Therefore, we must fail unification (go.dev/issue/60933).
					return false
				}
				// If we have inexact unification and one of x or y is a defined type, select the
				// defined type. This ensures that in a series of types, all matching against the
				// same type parameter, we infer a defined type if there is one, independent of
				// order. Type inference or assignment may fail, which is ok.
				// Selecting a defined type, if any, ensures that we don't lose the type name;
				// and since we have inexact unification, a value of equally named or matching
				// undefined type remains assignable (go.dev/issue/43056).
				//
				// Similarly, if we have inexact unification and there are no defined types but
				// channel types, select a directed channel, if any. This ensures that in a series
				// of unnamed types, all matching against the same type parameter, we infer the
				// directed channel if there is one, independent of order.
				// Selecting a directional channel, if any, ensures that a value of another
				// inexactly unifying channel type remains assignable (go.dev/issue/62157).
				//
				// If we have multiple defined channel types, they are either identical or we
				// have assignment conflicts, so we can ignore directionality in this case.
				//
				// If we have defined and literal channel types, a defined type wins to avoid
				// order dependencies.
				if mode&unifyModeExact == 0 {
					switch {
					case xn:
						// x is a defined type: nothing to do.
					case yn:
						// x is not a defined type and y is a defined type: select y.
						u.set(px, y)
					default:
						// Neither x nor y are defined types.
						if yc, _ := y.Underlying().(*types.Chan); yc != nil && yc.Dir() != types.SendRecv {
							// y is a directed channel type: select y.
							u.set(px, y)
						}
					}
				}
				return true
			}
			return false
		}
		// otherwise, infer type from y
		u.set(px, y)
		return true
	}

	// If u.EnableInterfaceInference is set and we don't require exact unification,
	// if both types are interfaces, one interface must have a subset of the
	// methods of the other and corresponding method signatures must unify.
	// If only one type is an interface, all its methods must be present in the
	// other type and corresponding method signatures must unify.

	// Unless we have exact unification, neither x nor y are interfaces now.
	// Except for unbound type parameters (see below), x and y must be structurally
	// equivalent to unify.

	// If we get here and x or y is a type parameter, they are unbound
	// (not recorded with the unifier).
	// Ensure that if we have at least one type parameter, it is in x
	// (the earlier swap checks for _recorded_ type parameters only).
	// This ensures that the switch switches on the type parameter.
	//
	// TODO(gri) Factor out type parameter handling from the switch.
	if isTypeParam(y) {
		x, y = y, x
	}

	// Type elements (array, slice, etc. elements) use emode for unification.
	// Element types must match exactly if the types are used in an assignment.
	emode := mode
	if mode&unifyModeAssign != 0 {
		emode |= unifyModeExact
	}

	// Continue with unaliased types but don't lose original alias names, if any (go.dev/issue/67628).
	xorig, x := x, types.Unalias(x)
	yorig, y := y, types.Unalias(y)

	switch x := x.(type) {
	case *types.Basic:
		// Basic types are singletons except for the rune and byte
		// aliases, thus we cannot solely rely on the x == y check
		// above. See also comment in TypeName.IsAlias.
		if y, ok := y.(*types.Basic); ok {
			return x.Kind() == y.Kind()
		}

	case *types.Array:
		// Two array types unify if they have the same array length
		// and their element types unify.
		if y, ok := y.(*types.Array); ok {
			// If one or both array lengths are unknown (< 0) due to some error,
			// assume they are the same to avoid spurious follow-on errors.
			return (x.Len() < 0 || y.Len() < 0 || x.Len() == y.Len()) && u.nify(x.Elem(), y.Elem(), emode)
		}

	case *types.Slice:
		// Two slice types unify if their element types unify.
		if y, ok := y.(*types.Slice); ok {
			return u.nify(x.Elem(), y.Elem(), emode)
		}

	case *types.Struct:
		// Two struct types unify if they have the same sequence of fields,
		// and if corresponding fields have the same names, their (field) types unify,
		// and they have identical tags. Two embedded fields are considered to have the same
		// name. Lower-case field names from different packages are always different.
		if y, ok := y.(*types.Struct); ok {
			if x.NumFields() == y.NumFields() {
				for i := range x.NumFields() {
					f := x.Field(i)
					g := y.Field(i)
					if f.Embedded() != g.Embedded() ||
						x.Tag(i) != y.Tag(i) ||
						!sameId(f, g.Pkg(), g.Name(), false) ||
						!u.nify(f.Type(), g.Type(), emode) {
						return false
					}
				}
				return true
			}
		}

	case *types.Pointer:
		// Two pointer types unify if their base types unify.
		if y, ok := y.(*types.Pointer); ok {
			return u.nify(x.Elem(), y.Elem(), emode)
		}

	case *types.Tuple:
		// Two tuples types unify if they have the same number of elements
		// and the types of corresponding elements unify.
		if y, ok := y.(*types.Tuple); ok {
			if x.Len() == y.Len() {
				if x != nil {
					for i := range x.Len() {
						v := x.At(i)
						w := y.At(i)
						if !u.nify(v.Type(), w.Type(), mode) {
							return false
						}
					}
				}
				return true
			}
		}

	case *types.Signature:
		// Two function types unify if they have the same number of parameters
		// and result values, corresponding parameter and result types unify,
		// and either both functions are variadic or neither is.
		// Parameter and result names are not required to match.
		// TODO(gri) handle type parameters or document why we can ignore them.
		if y, ok := y.(*types.Signature); ok {
			return x.Variadic() == y.Variadic() &&
				u.nify(x.Params(), y.Params(), emode) &&
				u.nify(x.Results(), y.Results(), emode)
		}

	case *types.Interface:
		return false
		// Below is the original code

		// Two interface types unify if they have the same set of methods with
		// the same names, and corresponding function types unify.
		// Lower-case method names from different packages are always different.
		// The order of the methods is irrelevant.
		// xset := x.typeSet()
		// yset := y.typeSet()
		// if xset.comparable != yset.comparable {
		// 	return false
		// }
		// if !xset.terms.equal(yset.terms) {
		// 	return false
		// }
		// a := xset.methods
		// b := yset.methods
		// if len(a) == len(b) {
		// 	// Interface types are the only types where cycles can occur
		// 	// that are not "terminated" via named types; and such cycles
		// 	// can only be created via method parameter types that are
		// 	// anonymous interfaces (directly or indirectly) embedding
		// 	// the current interface. Example:
		// 	//
		// 	//    type T interface {
		// 	//        m() interface{T}
		// 	//    }
		// 	//
		// 	// If two such (differently named) interfaces are compared,
		// 	// endless recursion occurs if the cycle is not detected.
		// 	//
		// 	// If x and y were compared before, they must be equal
		// 	// (if they were not, the recursion would have stopped);
		// 	// search the ifacePair stack for the same pair.
		// 	//
		// 	// This is a quadratic algorithm, but in practice these stacks
		// 	// are extremely short (bounded by the nesting depth of interface
		// 	// type declarations that recur via parameter types, an extremely
		// 	// rare occurrence). An alternative implementation might use a
		// 	// "visited" map, but that is probably less efficient overall.
		// 	q := &ifacePair{x, y, p}
		// 	for p != nil {
		// 		if p.identical(q) {
		// 			return true // same pair was compared before
		// 		}
		// 		p = p.prev
		// 	}
		// 	if debug {
		// 		assertSortedMethods(a)
		// 		assertSortedMethods(b)
		// 	}
		// 	for i, f := range a {
		// 		g := b[i]
		// 		if f.Id() != g.Id() || !u.nify(f.typ, g.typ, exact, q) {
		// 			return false
		// 		}
		// 	}
		// 	return true
		// }

	case *types.Map:
		// Two map types unify if their key and value types unify.
		if y, ok := y.(*types.Map); ok {
			return u.nify(x.Key(), y.Key(), emode) && u.nify(x.Elem(), y.Elem(), emode)
		}

	case *types.Chan:
		// Two channel types unify if their value types unify
		// and if they have the same direction.
		// The channel direction is ignored for inexact unification.
		if y, ok := y.(*types.Chan); ok {
			return (mode&unifyModeExact == 0 || x.Dir() == y.Dir()) && u.nify(x.Elem(), y.Elem(), emode)
		}

	case *types.Named:
		// Two named types unify if their type names originate in the same type declaration.
		// If they are instantiated, their type argument lists must unify.
		if y := asNamed(y); y != nil {
			// Check type arguments before origins so they unify
			// even if the origins don't match; for better error
			// messages (see go.dev/issue/53692).
			xargs := x.TypeArgs()
			yargs := y.TypeArgs()
			if xargs.Len() != yargs.Len() {
				return false
			}
			for i := range xargs.Len() {
				xarg := xargs.At(i)
				yarg := yargs.At(i)
				if !u.nify(xarg, yarg, mode) {
					return false
				}
			}
			return identicalOrigin(x, y)
		}

	case *types.TypeParam:
		// By definition, a valid type argument must be in the type set of
		// the respective type constraint. Therefore, the type argument's
		// underlying type must be in the set of underlying types of that
		// constraint. If there is a single such underlying type, it's the
		// constraint's core type. It must match the type argument's under-
		// lying type, irrespective of whether the actual type argument,
		// which may be a defined type, is actually in the type set (that
		// will be determined at instantiation time).
		// Thus, if we have the core type of an unbound type parameter,
		// we know the structure of the possible types satisfying such
		// parameters. Use that core type for further unification
		// (see go.dev/issue/50755 for a test case).
		if enableCoreTypeUnification {
			// Because the core type is always an underlying type,
			// unification will take care of matching against a
			// defined or literal type automatically.
			// If y is also an unbound type parameter, we will end
			// up here again with x and y swapped, so we don't
			// need to take care of that case separately.
			if cx := coreType(x); cx != nil {
				// If y is a defined type, it may not match against cx which
				// is an underlying type (incl. int, string, etc.). Use assign
				// mode here so that the unifier automatically takes under(y)
				// if necessary.
				return u.nify(cx, yorig, unifyModeAssign)
			}
		}
		// x != y and there's nothing to do

	case nil:
		// avoid a crash in case of nil type

	default:
		panic(fmt.Sprintf("u.nify(%s, %s, %d)", xorig, yorig, mode))
	}

	return false
}


================================================
FILE: gopls/internal/golang/completion/unimported.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

// unimported completion is invoked when the user types something like 'foo.xx',
// foo is known to be a package name not yet imported in the current file, and
// xx (or whatever the user has typed) is interpreted as a hint (pattern) for the
// member of foo that the user is looking for.
//
// This code looks for a suitable completion in a number of places. A 'suitable
// completion' is an exported symbol (so a type, const, var, or func) from package
// foo, which, after converting everything to lower case, has the pattern as a
// subsequence.
//
// The code looks for a suitable completion in
// 1. the imports of some other file of the current package,
// 2. the standard library,
// 3. the imports of some other file in the current workspace,
// 4. imports in the current module with 'foo' as the explicit package name,
// 5. the module cache,
// It stops at the first success.

import (
	"context"
	"fmt"
	"go/ast"
	"go/printer"
	"go/token"
	"path"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/golang/completion/snippet"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/modindex"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/versions"
)

func (c *completer) unimported(ctx context.Context, pkgname metadata.PackageName, prefix string) {
	wsIDs, ourIDs := c.findPackageIDs(pkgname)
	stdpkgs := c.stdlibPkgs(pkgname)
	if len(ourIDs) > 0 {
		// use the one in the current package, if possible
		items := c.pkgIDmatches(ctx, ourIDs, pkgname, prefix)
		if c.scoreList(items) {
			return
		}
	}
	// do the stdlib next.
	items := c.stdlibMatches(stdpkgs, pkgname, prefix)
	if c.scoreList(items) {
		return
	}

	// look in the rest of the workspace
	items = c.pkgIDmatches(ctx, wsIDs, pkgname, prefix)
	if c.scoreList(items) {
		return
	}

	// before looking in the module cache, maybe it is an explicit
	// package name used in this module
	if c.explicitPkgName(ctx, pkgname, prefix) {
		return
	}

	// look in the module cache
	items, err := c.modcacheMatches(pkgname, prefix)
	items = c.filterGoMod(ctx, items)
	if err == nil && c.scoreList(items) {
		return
	}

	// out of things to do
}

// prefer completion items that are referenced in the go.mod file
func (c *completer) filterGoMod(ctx context.Context, items []CompletionItem) []CompletionItem {
	if c.pkg.Metadata().Module == nil {
		// for std or GOROOT mode
		return items
	}
	gomod := c.pkg.Metadata().Module.GoMod
	uri := protocol.URIFromPath(gomod)
	fh, err := c.snapshot.ReadFile(ctx, uri)
	if err != nil {
		return items
	}
	pm, err := c.snapshot.ParseMod(ctx, fh)
	if err != nil || pm == nil {
		return items
	}
	// if any of the items match any of the req, just return those
	reqnames := []string{}
	for _, req := range pm.File.Require {
		reqnames = append(reqnames, req.Mod.Path)
	}
	better := []CompletionItem{}
	for _, compl := range items {
		if len(compl.AdditionalTextEdits) == 0 {
			continue
		}
		// import "foof/pkg"
		flds := strings.FieldsFunc(compl.AdditionalTextEdits[0].NewText, func(r rune) bool {
			return r == '"' || r == '/'
		})
		if len(flds) < 3 {
			continue
		}
		if slices.Contains(reqnames, flds[1]) {
			better = append(better, compl)
		}
	}
	if len(better) > 0 {
		return better
	}
	return items
}

// see if some file in the current package satisfied a foo. import
// because foo is an explicit package name (import foo "a.b.c")
func (c *completer) explicitPkgName(ctx context.Context, pkgname metadata.PackageName, prefix string) bool {
	for _, pgf := range c.pkg.CompiledGoFiles() {
		imports := pgf.File.Imports
		for _, imp := range imports {
			if imp.Name != nil && imp.Name.Name == string(pkgname) {
				path := strings.Trim(imp.Path.Value, `"`)
				if c.tryPath(ctx, metadata.PackagePath(path), string(pkgname), prefix) {
					return true // one is enough
				}
			}
		}
	}
	return false
}

// see if this path contains a usable import with explicit package name
func (c *completer) tryPath(ctx context.Context, path metadata.PackagePath, pkgname, prefix string) bool {
	packages := c.snapshot.MetadataGraph().ForPackagePath
	ids := []metadata.PackageID{}
	for _, pkg := range packages[path] { // could there ever be more than one?
		ids = append(ids, pkg.ID) // pkg.ID. ID: "math/rand" but Name: "rand"
	}
	items := c.pkgIDmatches(ctx, ids, metadata.PackageName(pkgname), prefix)
	return c.scoreList(items)
}

// find all the packageIDs for packages in the workspace that have the desired name
// thisPkgIDs contains the ones known to the current package, wsIDs contains the others
func (c *completer) findPackageIDs(pkgname metadata.PackageName) (wsIDs, thisPkgIDs []metadata.PackageID) {
	g := c.snapshot.MetadataGraph()
	for pid, pkg := range c.snapshot.MetadataGraph().Packages {
		if pkg.Name != pkgname {
			continue
		}
		imports := g.ImportedBy[pid]
		// Metadata is not canonical: it may be held onto by a package. Therefore,
		// we must compare by ID.
		thisPkg := func(mp *metadata.Package) bool { return mp.ID == c.pkg.Metadata().ID }
		if slices.ContainsFunc(imports, thisPkg) {
			thisPkgIDs = append(thisPkgIDs, pid)
		} else {
			wsIDs = append(wsIDs, pid)
		}
	}
	return
}

// find all the stdlib packages that have the desired name
func (c *completer) stdlibPkgs(pkgname metadata.PackageName) []metadata.PackagePath {
	var pkgs []metadata.PackagePath // stlib packages that match pkg
	for pkgpath := range stdlib.PackageSymbols {
		v := metadata.PackageName(path.Base(pkgpath))
		if v == pkgname {
			pkgs = append(pkgs, metadata.PackagePath(pkgpath))
		} else if imports.WithoutVersion(string(pkgpath)) == string(pkgname) {
			pkgs = append(pkgs, metadata.PackagePath(pkgpath))
		}
	}
	return pkgs
}

// return CompletionItems for all matching symbols in the packages in ids.
func (c *completer) pkgIDmatches(ctx context.Context, ids []metadata.PackageID, pkgname metadata.PackageName, prefix string) []CompletionItem {
	pattern := strings.ToLower(prefix)
	allpkgsyms, err := c.snapshot.Symbols(ctx, ids...)
	if err != nil {
		return nil // would if be worth retrying the ids one by one?
	}
	if len(allpkgsyms) != len(ids) {
		bug.Reportf("Symbols returned %d values for %d pkgIDs", len(allpkgsyms), len(ids))
		return nil
	}
	var got []CompletionItem
	for i, pkgID := range ids {
		pkg := c.snapshot.MetadataGraph().Packages[pkgID]
		if pkg == nil {
			bug.Reportf("no metadata for %s", pkgID)
			continue // something changed underfoot, otherwise can't happen
		}
		pkgsyms := allpkgsyms[i]
		pkgfname := pkgsyms.Files[0].Path()
		if !imports.CanUse(c.filename, pkgfname) {
			// avoid unusable internal, etc
			continue
		}
		// are any of these any good?
		for np, asym := range pkgsyms.Symbols {
			for _, sym := range asym {
				if !token.IsExported(sym.Name) {
					continue
				}
				if !usefulCompletion(sym.Name, pattern) {
					// for json.U, the existing code finds InvalidUTF8Error
					continue
				}
				var params []string
				var kind protocol.CompletionItemKind
				var detail string
				switch sym.Kind {
				case protocol.Function:
					foundURI := pkgsyms.Files[np]
					fh, _ := c.snapshot.ReadFile(ctx, foundURI)
					pgf, err := c.snapshot.ParseGo(ctx, fh, 0)
					if err == nil {
						params = funcParams(pgf.File, sym.Name)
					}
					kind = protocol.FunctionCompletion
					detail = fmt.Sprintf("func (from %q)", pkg.PkgPath)
				case protocol.Variable, protocol.Struct:
					kind = protocol.VariableCompletion
					detail = fmt.Sprintf("var (from %q)", pkg.PkgPath)
				case protocol.Constant:
					kind = protocol.ConstantCompletion
					detail = fmt.Sprintf("const (from %q)", pkg.PkgPath)
				default:
					continue
				}
				got = c.appendNewItem(got, sym.Name,
					detail,
					pkg.PkgPath,
					kind,
					pkgname, params)
			}
		}
	}
	return got
}

// return CompletionItems for all the matches in packages in pkgs.
func (c *completer) stdlibMatches(pkgs []metadata.PackagePath, pkg metadata.PackageName, prefix string) []CompletionItem {
	// check for deprecated symbols someday
	got := make([]CompletionItem, 0)
	pattern := strings.ToLower(prefix)
	// avoid non-determinacy, especially for marker tests
	slices.Sort(pkgs)
	for _, candpkg := range pkgs {
		if std, ok := stdlib.PackageSymbols[string(candpkg)]; ok {
			for _, sym := range std {
				if !usefulCompletion(sym.Name, pattern) {
					continue
				}
				if !versions.AtLeast(c.goversion, sym.Version.String()) {
					continue
				}
				var kind protocol.CompletionItemKind
				var detail string
				var params []string
				switch sym.Kind {
				case stdlib.Func:
					params = parseSignature(sym.Signature)
					kind = protocol.FunctionCompletion
					detail = fmt.Sprintf("func (from %q)", candpkg)
				case stdlib.Const:
					kind = protocol.ConstantCompletion
					detail = fmt.Sprintf("const (from %q)", candpkg)
				case stdlib.Var:
					kind = protocol.VariableCompletion
					detail = fmt.Sprintf("var (from %q)", candpkg)
				case stdlib.Type:
					kind = protocol.VariableCompletion
					detail = fmt.Sprintf("type (from %q)", candpkg)
				default:
					continue
				}
				got = c.appendNewItem(got, sym.Name,
					detail,
					candpkg,
					kind,
					pkg, params)
			}
		}
	}
	return got
}

func (c *completer) modcacheMatches(pkg metadata.PackageName, prefix string) ([]CompletionItem, error) {
	ix, err := c.snapshot.View().ModcacheIndex()
	if err != nil {
		return nil, err
	}
	// retrieve everything and let usefulCompletion() and the matcher sort them out
	cands := ix.Lookup(string(pkg), "", true)
	lx := len(cands)
	got := make([]CompletionItem, 0, lx)
	pattern := strings.ToLower(prefix)
	for _, cand := range cands {
		if !usefulCompletion(cand.Name, pattern) {
			continue
		}
		var params []string
		var kind protocol.CompletionItemKind
		var detail string
		switch cand.Type {
		case modindex.Func:
			for _, f := range cand.Sig {
				params = append(params, fmt.Sprintf("%s %s", f.Arg, f.Type))
			}
			kind = protocol.FunctionCompletion
			detail = fmt.Sprintf("func (from %s)", cand.ImportPath)
		case modindex.Var:
			kind = protocol.VariableCompletion
			detail = fmt.Sprintf("var (from %s)", cand.ImportPath)
		case modindex.Const:
			kind = protocol.ConstantCompletion
			detail = fmt.Sprintf("const (from %s)", cand.ImportPath)
		case modindex.Type: // might be a type alias
			kind = protocol.VariableCompletion
			detail = fmt.Sprintf("type (from %s)", cand.ImportPath)
		default:
			continue
		}
		got = c.appendNewItem(got, cand.Name,
			detail,
			metadata.PackagePath(cand.ImportPath),
			kind,
			pkg, params)
	}
	return got, nil
}

func (c *completer) appendNewItem(got []CompletionItem, name, detail string, path metadata.PackagePath, kind protocol.CompletionItemKind, pkg metadata.PackageName, params []string) []CompletionItem {
	item := CompletionItem{
		Label:      name,
		Detail:     detail,
		InsertText: name,
		Kind:       kind,
	}
	imp := importInfo{
		importPath: string(path),
		name:       string(pkg),
	}
	if imports.ImportPathToAssumedName(string(path)) == string(pkg) {
		imp.name = ""
	}
	item.AdditionalTextEdits, _ = c.importEdits(&imp)
	if params != nil {
		var sn snippet.Builder
		c.functionCallSnippet(name, nil, params, &sn)
		item.snippet = &sn
	}
	got = append(got, item)
	return got
}

// score the list. Return true if any item is added to c.items
func (c *completer) scoreList(items []CompletionItem) bool {
	ret := false
	for _, item := range items {
		item.Score = float64(c.matcher.Score(item.Label))
		if item.Score > 0 {
			c.items = append(c.items, item)
			ret = true
		}
	}
	return ret
}

// pattern is always the result of strings.ToLower
func usefulCompletion(name, pattern string) bool {
	// this travesty comes from foo.(type) somehow. see issue59096.txt
	if pattern == "_" {
		return true
	}
	// convert both to lower case, and then the runes in the pattern have to occur, in order,
	// in the name
	cand := strings.ToLower(name)
	for _, r := range pattern {
		ix := strings.IndexRune(cand, r)
		if ix < 0 {
			return false
		}
		cand = cand[ix+1:]
	}
	return true
}

// return a printed version of the function arguments for snippets
func funcParams(f *ast.File, fname string) []string {
	var params []string
	setParams := func(list *ast.FieldList) {
		if list == nil {
			return
		}
		var cfg printer.Config // slight overkill
		param := func(name string, typ ast.Expr) {
			var buf strings.Builder
			buf.WriteString(name)
			buf.WriteByte(' ')
			cfg.Fprint(&buf, token.NewFileSet(), typ) // ignore error
			params = append(params, buf.String())
		}

		for _, field := range list.List {
			if field.Names != nil {
				for _, name := range field.Names {
					param(name.Name, field.Type)
				}
			} else {
				param("_", field.Type)
			}
		}
	}
	for _, n := range f.Decls {
		switch x := n.(type) {
		case *ast.FuncDecl:
			if x.Recv == nil && x.Name.Name == fname {
				setParams(x.Type.Params)
			}
		}
	}
	return params
}

// extract the formal parameters from the signature.
// func[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2) -> []{"dst M1", "src M2"}
// func[K comparable, V any](seq iter.Seq2[K, V]) map[K]V -> []{"seq iter.Seq2[K, V]"}
// func(args ...any) *Logger -> []{"args ...any"}
// func[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool) -> []{"m M", "del func(K, V) bool"}
func parseSignature(sig string) []string {
	var level int       // nesting level of delimiters
	var processing bool // are we doing the params
	var last int        // start of current parameter
	var params []string
	for i := range len(sig) {
		switch sig[i] {
		case '[', '{':
			level++
		case ']', '}':
			level--
		case '(':
			level++
			if level == 1 {
				processing = true
				last = i + 1
			}
		case ')':
			level--
			if level == 0 && processing { // done
				if i > last {
					params = append(params, strings.TrimSpace(sig[last:i]))
				}
				return params
			}
		case ',':
			if level == 1 && processing {
				params = append(params, strings.TrimSpace(sig[last:i]))
				last = i + 1
			}
		}
	}
	return nil
}


================================================
FILE: gopls/internal/golang/completion/util.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/typeparams"
)

// exprAtPos returns the index of the expression containing pos.
func exprAtPos(pos token.Pos, args []ast.Expr) int {
	for i, expr := range args {
		if expr.Pos() <= pos && pos <= expr.End() {
			return i
		}
	}
	return len(args)
}

// eachField invokes fn for each field that can be selected from a
// value of type T.
func eachField(T types.Type, fn func(*types.Var)) {
	// TODO(adonovan): this algorithm doesn't exclude ambiguous
	// selections that match more than one field/method.
	// types.NewSelectionSet should do that for us.

	// for termination on recursive types
	var seen typeutil.Map

	var visit func(T types.Type)
	visit = func(T types.Type) {
		// T may be a Struct, optionally Named, with an optional
		// Pointer (with optional Aliases at every step!):
		// Consider: type T *struct{ f int }; _ = T(nil).f
		if T, ok := typeparams.Deref(T).Underlying().(*types.Struct); ok {
			if seen.At(T) != nil {
				return
			}

			for f := range T.Fields() {
				fn(f)
				if f.Anonymous() {
					seen.Set(T, true)
					visit(f.Type())
				}
			}
		}
	}
	visit(T)
}

// typeIsValid reports whether typ doesn't contain any Invalid types.
func typeIsValid(typ types.Type) bool {
	// Check named types separately, because we don't want
	// to call Underlying() on them to avoid problems with recursive types.
	if _, ok := types.Unalias(typ).(*types.Named); ok {
		return true
	}

	switch typ := typ.Underlying().(type) {
	case *types.Basic:
		return typ.Kind() != types.Invalid
	case *types.Array:
		return typeIsValid(typ.Elem())
	case *types.Slice:
		return typeIsValid(typ.Elem())
	case *types.Pointer:
		return typeIsValid(typ.Elem())
	case *types.Map:
		return typeIsValid(typ.Key()) && typeIsValid(typ.Elem())
	case *types.Chan:
		return typeIsValid(typ.Elem())
	case *types.Signature:
		return typeIsValid(typ.Params()) && typeIsValid(typ.Results())
	case *types.Tuple:
		for v := range typ.Variables() {
			if !typeIsValid(v.Type()) {
				return false
			}
		}
		return true
	case *types.Struct, *types.Interface:
		// Don't bother checking structs, interfaces for validity.
		return true
	default:
		return false
	}
}

// resolveInvalid traverses the node of the AST that defines the scope
// containing the declaration of obj, and attempts to find a user-friendly
// name for its invalid type. The resulting Object and its Type are fake.
func resolveInvalid(fset *token.FileSet, obj types.Object, node ast.Node, info *types.Info) types.Object {
	var resultExpr ast.Expr
	ast.Inspect(node, func(node ast.Node) bool {
		switch n := node.(type) {
		case *ast.ValueSpec:
			for _, name := range n.Names {
				if info.Defs[name] == obj {
					resultExpr = n.Type
				}
			}
			return false
		case *ast.Field: // This case handles parameters and results of a FuncDecl or FuncLit.
			for _, name := range n.Names {
				if info.Defs[name] == obj {
					resultExpr = n.Type
				}
			}
			return false
		default:
			return true
		}
	})
	// Construct a fake type for the object and return a fake object with this type.
	typename := golang.FormatNode(fset, resultExpr)
	typ := types.NewNamed(types.NewTypeName(token.NoPos, obj.Pkg(), typename, nil), types.Typ[types.Invalid], nil)
	v := types.NewVar(obj.Pos(), obj.Pkg(), obj.Name(), typ)
	v.SetKind(types.PackageVar)
	return v
}

// TODO(adonovan): inline these.
func isVar(obj types.Object) bool      { return is[*types.Var](obj) }
func isTypeName(obj types.Object) bool { return is[*types.TypeName](obj) }
func isFunc(obj types.Object) bool     { return is[*types.Func](obj) }
func isPkgName(obj types.Object) bool  { return is[*types.PkgName](obj) }

// isPointer reports whether T is a Pointer, or an alias of one.
// It returns false for a Named type whose Underlying is a Pointer.
//
// TODO(adonovan): shouldn't this use CoreType(T)?
func isPointer(T types.Type) bool { return is[*types.Pointer](types.Unalias(T)) }

// isEmptyInterface whether T is a (possibly Named or Alias) empty interface
// type, such that every type is assignable to T.
//
// isEmptyInterface returns false for type parameters, since they have
// different assignability rules.
func isEmptyInterface(T types.Type) bool {
	if _, ok := T.(*types.TypeParam); ok {
		return false
	}
	intf, _ := T.Underlying().(*types.Interface)
	return intf != nil && intf.Empty()
}

func isUntyped(T types.Type) bool {
	if basic, ok := types.Unalias(T).(*types.Basic); ok {
		return basic.Info()&types.IsUntyped > 0
	}
	return false
}

func deslice(T types.Type) types.Type {
	if slice, ok := T.Underlying().(*types.Slice); ok {
		return slice.Elem()
	}
	return nil
}

// enclosingSelector returns the enclosing *ast.SelectorExpr when pos is in the
// selector.
func enclosingSelector(path []ast.Node, pos token.Pos) *ast.SelectorExpr {
	if len(path) == 0 {
		return nil
	}

	if sel, ok := path[0].(*ast.SelectorExpr); ok {
		return sel
	}

	// TODO(adonovan): consider ast.ParenExpr (e.g. (x).name)
	if _, ok := path[0].(*ast.Ident); ok && len(path) > 1 {
		if sel, ok := path[1].(*ast.SelectorExpr); ok && pos >= sel.Sel.Pos() {
			return sel
		}
	}

	return nil
}

// enclosingDeclLHS returns LHS idents from containing value spec or
// assign statement.
func enclosingDeclLHS(path []ast.Node) []*ast.Ident {
	for _, n := range path {
		switch n := n.(type) {
		case *ast.ValueSpec:
			return n.Names
		case *ast.AssignStmt:
			ids := make([]*ast.Ident, 0, len(n.Lhs))
			for _, e := range n.Lhs {
				if id, ok := e.(*ast.Ident); ok {
					ids = append(ids, id)
				}
			}
			return ids
		}
	}

	return nil
}

// exprObj returns the types.Object associated with the *ast.Ident or
// *ast.SelectorExpr e.
func exprObj(info *types.Info, e ast.Expr) types.Object {
	var ident *ast.Ident
	switch expr := e.(type) {
	case *ast.Ident:
		ident = expr
	case *ast.SelectorExpr:
		ident = expr.Sel
	default:
		return nil
	}

	return info.ObjectOf(ident)
}

// typeConversion returns the type being converted to if call is a type
// conversion expression.
func typeConversion(call *ast.CallExpr, info *types.Info) types.Type {
	// Type conversion (e.g. "float64(foo)").
	if fun, _ := exprObj(info, call.Fun).(*types.TypeName); fun != nil {
		return fun.Type()
	}

	return nil
}

// fieldsAccessible returns whether s has at least one field accessible by p.
func fieldsAccessible(s *types.Struct, p *types.Package) bool {
	for f := range s.Fields() {
		if f.Exported() || f.Pkg() == p {
			return true
		}
	}
	return false
}

// prevStmt returns the statement that precedes the statement containing pos.
// For example:
//
//	foo := 1
//	bar(1 + 2<>)
//
// If "<>" is pos, prevStmt returns "foo := 1"
func prevStmt(pos token.Pos, path []ast.Node) ast.Stmt {
	var blockLines []ast.Stmt
	for i := 0; i < len(path) && blockLines == nil; i++ {
		switch n := path[i].(type) {
		case *ast.BlockStmt:
			blockLines = n.List
		case *ast.CommClause:
			blockLines = n.Body
		case *ast.CaseClause:
			blockLines = n.Body
		}
	}

	for i := len(blockLines) - 1; i >= 0; i-- {
		if blockLines[i].End() < pos {
			return blockLines[i]
		}
	}

	return nil
}

// isBasicKind returns whether t is a basic type of kind k.
func isBasicKind(t types.Type, k types.BasicInfo) bool {
	b, _ := t.Underlying().(*types.Basic)
	return b != nil && b.Info()&k > 0
}

func (c *completer) editText(from, to token.Pos, newText string) ([]protocol.TextEdit, error) {
	start, end, err := safetoken.Offsets(c.pgf.Tok, from, to)
	if err != nil {
		return nil, err // can't happen: from/to came from c
	}
	return protocol.EditsFromDiffEdits(c.mapper, []diff.Edit{{
		Start: start,
		End:   end,
		New:   newText,
	}})
}

// assignableTo is like types.AssignableTo, but returns false if
// either type is invalid.
func assignableTo(x, to types.Type) bool {
	if types.Unalias(x) == types.Typ[types.Invalid] ||
		types.Unalias(to) == types.Typ[types.Invalid] {
		return false
	}

	return types.AssignableTo(x, to)
}

// convertibleTo is like types.ConvertibleTo, but returns false if
// either type is invalid.
func convertibleTo(x, to types.Type) bool {
	if types.Unalias(x) == types.Typ[types.Invalid] ||
		types.Unalias(to) == types.Typ[types.Invalid] {
		return false
	}

	return types.ConvertibleTo(x, to)
}


================================================
FILE: gopls/internal/golang/counters.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import "golang.org/x/telemetry/counter"

// Proposed counters for evaluating gopls extract, inline, and package rename. These counters
// increment when the user attempts to perform one of these operations,
// regardless of whether it succeeds.
var (
	countExtractFunction    = counter.New("gopls/extract:func")
	countExtractMethod      = counter.New("gopls/extract:method")
	countExtractVariable    = counter.New("gopls/extract:variable")
	countExtractVariableAll = counter.New("gopls/extract:variable-all")

	countInlineCall     = counter.New("gopls/inline:call")
	countInlineVariable = counter.New("gopls/inline:variable")

	countRenamePackage = counter.New("gopls/renamekind:package")
)


================================================
FILE: gopls/internal/golang/definition.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"regexp"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
)

// Definition handles the textDocument/definition request for Go files.
func Definition(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	ctx, done := event.Start(ctx, "golang.Definition")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(start, end) // can't fail

	// Handle the case where the range is in an import.
	importLocations, err := importDefinition(ctx, snapshot, pkg, pgf, start, end)
	if err != nil {
		return nil, err
	}
	if len(importLocations) > 0 {
		return importLocations, nil
	}

	// Handle the case where the cursor is in the package name.
	// We use "<= End" to accept a query immediately after the package name.
	if pgf.File != nil && astutil.NodeContains(pgf.File.Name, astutil.RangeOf(start, end)) {
		// If there's no package documentation, just use current file.
		declFile := pgf
		for _, pgf := range pkg.CompiledGoFiles() {
			if pgf.File.Name != nil && pgf.File.Doc != nil {
				declFile = pgf
				break
			}
		}
		loc, err := declFile.NodeLocation(declFile.File.Name)
		if err != nil {
			return nil, err
		}
		return []protocol.Location{loc}, nil
	}

	// Handle the case where the cursor is in a linkname directive.
	locations, err := linknameDefinition(ctx, snapshot, pgf.Mapper, rng)
	if !errors.Is(err, ErrNoLinkname) {
		return locations, err // may be success or failure
	}

	// Handle the case where the cursor is in an embed directive.
	locations, err = embedDefinition(pgf.Mapper, rng)
	if !errors.Is(err, ErrNoEmbed) {
		return locations, err // may be success or failure
	}

	// Handle the case where the cursor is in a doc link.
	locations, err = docLinkDefinition(ctx, snapshot, pkg, pgf, start, end)
	if !errors.Is(err, errNoCommentReference) {
		return locations, err // may be success or failure
	}

	// Handle definition requests for various special kinds of syntax node.
	switch node := cur.Node().(type) {
	// Handle the case where the cursor is on a return statement by jumping to the result variables.
	case *ast.ReturnStmt:
		var funcType *ast.FuncType
		for c := range cur.Enclosing() {
			switch n := c.Node().(type) {
			case *ast.FuncLit:
				funcType = n.Type
			case *ast.FuncDecl:
				funcType = n.Type
			}
			if funcType != nil {
				break
			}
		}
		// Inv: funcType != nil, as a return stmt cannot appear outside a function.
		if funcType.Results == nil {
			return nil, nil // no result variables
		}
		loc, err := pgf.NodeLocation(funcType.Results)
		if err != nil {
			return nil, err
		}
		return []protocol.Location{loc}, nil

	case *ast.BranchStmt:
		// Handle the case where the cursor is on a goto, break or continue statement by returning the
		// location of the label, the closing brace of the relevant block statement, or the
		// start of the relevant loop, respectively.
		label, isLabeled := pkg.TypesInfo().Uses[node.Label].(*types.Label)
		switch node.Tok {
		case token.GOTO:
			if !isLabeled {
				return nil, fmt.Errorf("undefined label")
			}
			loc, err := pgf.PosLocation(label.Pos(), label.Pos()+token.Pos(len(label.Name())))
			if err != nil {
				return nil, err
			}
			return []protocol.Location{loc}, nil

		case token.BREAK, token.CONTINUE:
			// Find innermost relevant ancestor for break/continue.
			for c := range cur.Enclosing() {
				if isLabeled {
					l, ok := c.Parent().Node().(*ast.LabeledStmt)
					if !(ok && l.Label.Name == label.Name()) {
						continue
					}
				}
				switch n := c.Node().(type) {
				case *ast.ForStmt, *ast.RangeStmt:
					var start, end token.Pos
					if node.Tok == token.BREAK {
						start, end = n.End()-token.Pos(len("}")), n.End()
					} else { // CONTINUE
						start, end = n.Pos(), n.Pos()+token.Pos(len("for"))
					}
					loc, err := pgf.PosLocation(start, end)
					if err != nil {
						return nil, err
					}
					return []protocol.Location{loc}, nil
				case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
					if node.Tok == token.BREAK {
						loc, err := pgf.PosLocation(n.End()-1, n.End())
						if err != nil {
							return nil, err
						}
						return []protocol.Location{loc}, nil
					}
				case *ast.FuncDecl, *ast.FuncLit:
					// bad syntax; avoid jumping outside the current function
					return nil, nil
				}
			}
		}
	}

	// The general case: the cursor is on (or near) an identifier.
	objects, err := objectsAt(pkg.TypesInfo(), cur)
	if err != nil {
		return nil, nil
	}
	obj := objects[0].obj
	cur = objects[0].cur // nearby
	id, ok := cur.Node().(*ast.Ident)
	if !ok {
		// objectsAt can return a non-Ident (e.g. ImportSpec),
		// but we dealt with them earlier. Can't happen?
		return nil, nil
	}

	// If the query position was an embedded field, we want to jump
	// to the field's type definition, not the field's definition (#42254).
	if v, ok := obj.(*types.Var); ok && v.Embedded() {
		// types.Info.Uses contains the embedded field's *types.TypeName.
		if typeName := pkg.TypesInfo().Uses[id]; typeName != nil {
			obj = typeName
		}
	}

	// Non-go (e.g. assembly) symbols
	//
	// When already at the definition of a Go function without
	// a body, we jump to its non-Go (C or assembly) definition.
	for _, decl := range pgf.File.Decls {
		if decl, ok := decl.(*ast.FuncDecl); ok &&
			decl.Body == nil &&
			astutil.NodeContains(decl.Name, astutil.RangeOf(start, end)) {
			return nonGoDefinition(ctx, snapshot, pkg, decl.Name.Name)
		}
	}

	// Finally, map the object position.
	loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, obj)
	if err != nil {
		return nil, err
	}
	return []protocol.Location{loc}, nil
}

// builtinDecl returns the parsed Go file and node corresponding to a builtin
// object, which may be a universe object or part of types.Unsafe, as well as
// its declaring identifier.
func builtinDecl(ctx context.Context, snapshot *cache.Snapshot, obj types.Object) (*parsego.File, *ast.Ident, error) {
	// declaringIdent returns the file-level declaration node (as reported by
	// ast.Object) and declaring identifier of name using legacy (go/ast) object
	// resolution.
	declaringIdent := func(file *ast.File, name string) (ast.Node, *ast.Ident, error) {
		astObj := file.Scope.Lookup(name)
		if astObj == nil {
			// Every built-in should have documentation syntax.
			// However, it is possible to reach this statement by
			// commenting out declarations in {builtin,unsafe}.go.
			return nil, nil, fmt.Errorf("internal error: no object for %s", name)
		}
		decl, ok := astObj.Decl.(ast.Node)
		if !ok {
			return nil, nil, bug.Errorf("internal error: no declaration for %s", obj.Name())
		}
		var ident *ast.Ident
		switch node := decl.(type) {
		case *ast.Field:
			for _, id := range node.Names {
				if id.Name == name {
					ident = id
				}
			}
		case *ast.ValueSpec:
			for _, id := range node.Names {
				if id.Name == name {
					ident = id
				}
			}
		case *ast.TypeSpec:
			ident = node.Name
		case *ast.Ident:
			ident = node
		case *ast.FuncDecl:
			ident = node.Name
		case *ast.ImportSpec, *ast.LabeledStmt, *ast.AssignStmt:
			// Not reachable for imported objects.
		default:
			return nil, nil, bug.Errorf("internal error: unexpected decl type %T", decl)
		}
		if ident == nil {
			return nil, nil, bug.Errorf("internal error: no declaring identifier for %s", obj.Name())
		}
		return decl, ident, nil
	}

	var (
		pgf   *parsego.File
		ident *ast.Ident
		err   error
	)
	if obj.Pkg() == types.Unsafe {
		// package "unsafe":
		// parse $GOROOT/src/unsafe/unsafe.go
		//
		// (Strictly, we shouldn't assume that the ID of a std
		// package is its PkgPath, but no Bazel+gopackagesdriver
		// users have complained about this yet.)
		unsafe := snapshot.Metadata("unsafe")
		if unsafe == nil {
			// If the type checker somehow resolved 'unsafe', we must have metadata
			// for it.
			return nil, nil, bug.Errorf("no metadata for package 'unsafe'")
		}
		uri := unsafe.GoFiles[0]
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, nil, err
		}
		// TODO(rfindley): treat unsafe symmetrically with the builtin file. Either
		// pre-parse them both, or look up metadata for both.
		pgf, err = snapshot.ParseGo(ctx, fh, parsego.Full&^parser.SkipObjectResolution)
		if err != nil {
			return nil, nil, err
		}
		_, ident, err = declaringIdent(pgf.File, obj.Name())
		if err != nil {
			return nil, nil, err
		}
	} else {
		// pseudo-package "builtin":
		// use parsed $GOROOT/src/builtin/builtin.go
		pgf, err = snapshot.BuiltinFile(ctx)
		if err != nil {
			return nil, nil, err
		}

		if obj.Parent() == types.Universe {
			// built-in function or type
			_, ident, err = declaringIdent(pgf.File, obj.Name())
			if err != nil {
				return nil, nil, err
			}
		} else if obj.Name() == "Error" {
			// error.Error method
			decl, _, err := declaringIdent(pgf.File, "error")
			if err != nil {
				return nil, nil, err
			}
			field := decl.(*ast.TypeSpec).Type.(*ast.InterfaceType).Methods.List[0]
			ident = field.Names[0]
		} else {
			return nil, nil, bug.Errorf("unknown built-in %v", obj)
		}
	}
	_ = ident.Name // ident != nil

	return pgf, ident, nil
}

// importDefinition returns locations defining a package referenced by the
// import spec containing pos.
//
// If pos is not inside an import spec, it returns nil, nil.
func importDefinition(ctx context.Context, s *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) ([]protocol.Location, error) {
	var imp *ast.ImportSpec
	for _, spec := range pgf.File.Imports {
		// We use "<= End" to accept a query immediately after an ImportSpec.
		if astutil.NodeContains(spec.Path, astutil.RangeOf(start, end)) {
			imp = spec
		}
	}
	if imp == nil {
		return nil, nil
	}

	importPath := metadata.UnquoteImportPath(imp)
	impID := pkg.Metadata().DepsByImpPath[importPath]
	if impID == "" {
		return nil, fmt.Errorf("failed to resolve import %q", importPath)
	}
	impMetadata := s.Metadata(impID)
	if impMetadata == nil {
		return nil, fmt.Errorf("missing information for package %q", impID)
	}

	var locs []protocol.Location
	for _, f := range impMetadata.CompiledGoFiles {
		fh, err := s.ReadFile(ctx, f)
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			continue
		}
		pgf, err := s.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			continue
		}
		loc, err := pgf.NodeLocation(pgf.File)
		if err != nil {
			return nil, err
		}
		locs = append(locs, loc)
	}

	if len(locs) == 0 {
		return nil, fmt.Errorf("package %q has no readable files", impID) // incl. unsafe
	}

	return locs, nil
}

// ObjectLocation returns the location of the declaring identifier of obj.
// If valid, obj.Pos() must be mapped by fset.
// It may need to read the declaring file content, hence (ctx, s).
// It supports the builtin and unsafe pseudo-packages.
func ObjectLocation(ctx context.Context, fset *token.FileSet, snapshot *cache.Snapshot, obj types.Object) (protocol.Location, error) {
	if isBuiltin(obj) {
		// Returns fake source declaration in {builtin,unsafe}.go.
		pgf, ident, err := builtinDecl(ctx, snapshot, obj)
		if err != nil {
			return protocol.Location{}, err
		}
		return pgf.NodeLocation(ident)
	}

	// An imported Go package has a package-local, unqualified name.
	// When the name matches the imported package name, there is usually
	// no identifier in the import spec with the local package name.
	//
	// For example:
	// 	import "go/‸ast" 	// name "ast" matches package name
	// 	import ‸a "go/ast"  	// name "a" does not match package name
	//
	// When the identifier does not appear in the source, have the range
	// of the object be the import path, including quotes.
	//
	// But this is just a heuristic, and it's wrong in this case:
	// 	import ‸ast "go/ast"  	// name matches (spurious result is `ast "go/`)
	nameLen := len(obj.Name())
	if pkgName, ok := obj.(*types.PkgName); ok && pkgName.Imported().Name() == pkgName.Name() {
		nameLen = len(pkgName.Imported().Path()) + len(`""`)
	}

	var (
		start = obj.Pos()
		end   = start + token.Pos(nameLen)
	)
	file := fset.File(start)
	if file == nil {
		return protocol.Location{}, bug.Errorf("FileSet does not map Pos %d", start)
	}
	uri := protocol.URIFromPath(file.Name())
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return protocol.Location{}, err
	}
	content, err := fh.Content()
	if err != nil {
		return protocol.Location{}, err
	}
	// TODO(rfindley): avoid the duplicate column mapping here, by associating a
	// column mapper with each file handle.
	m := protocol.NewMapper(fh.URI(), content)
	return m.PosLocation(file, start, end)
}

// nonGoDefinition returns the location of the definition of a non-Go symbol.
// Only assembly is supported for now.
func nonGoDefinition(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, symbol string) ([]protocol.Location, error) {
	// Examples:
	//   TEXT runtime·foo(SB)
	//   TEXT ·foo<ABIInternal>(SB)
	// TODO(adonovan): why does ^TEXT cause it not to match?
	pattern := regexp.MustCompile("TEXT\\b.*·(" + regexp.QuoteMeta(symbol) + ")[\\(<]")

	for _, uri := range pkg.Metadata().OtherFiles {
		if strings.HasSuffix(uri.Path(), ".s") {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return nil, err // context cancelled
			}
			content, err := fh.Content()
			if err != nil {
				continue // can't read file
			}
			if match := pattern.FindSubmatchIndex(content); match != nil {
				mapper := protocol.NewMapper(uri, content)
				loc, err := mapper.OffsetLocation(match[2], match[3])
				if err != nil {
					return nil, err
				}
				return []protocol.Location{loc}, nil
			}
		}
	}

	// TODO(adonovan): try C files

	// This may be reached for functions that aren't implemented
	// in assembly (e.g. compiler intrinsics like getg).
	return nil, fmt.Errorf("can't find non-Go definition of %s", symbol)
}


================================================
FILE: gopls/internal/golang/diagnostics.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
)

// DiagnoseFile returns pull-based diagnostics for the given file.
func DiagnoseFile(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) ([]*cache.Diagnostic, error) {
	mp, err := snapshot.NarrowestMetadataForFile(ctx, uri)
	if err != nil {
		return nil, err
	}

	// TODO(rfindley): consider analysing the package concurrently to package
	// diagnostics.

	// Get package (list/parse/type check) diagnostics.
	pkgDiags, err := snapshot.PackageDiagnostics(ctx, mp.ID)
	if err != nil {
		return nil, err
	}
	diags := pkgDiags[uri]

	// Get analysis diagnostics.
	pkgAnalysisDiags, err := snapshot.Analyze(ctx, map[PackageID]*metadata.Package{mp.ID: mp}, nil)
	if err != nil {
		return nil, err
	}
	analysisDiags := moremaps.Group(pkgAnalysisDiags, byURI)[uri]

	// Return the merged set of file diagnostics, combining type error analyses
	// with type error diagnostics.
	return CombineDiagnostics(diags, analysisDiags), nil
}

// Analyze reports go/analysis-framework diagnostics in the specified package.
//
// If the provided tracker is non-nil, it may be used to provide notifications
// of the ongoing analysis pass.
//
// TODO(rfindley): merge this with snapshot.Analyze.
func Analyze(ctx context.Context, snapshot *cache.Snapshot, pkgIDs map[PackageID]*metadata.Package, tracker *progress.Tracker) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	// Exit early if the context has been canceled. This also protects us
	// from a race on Options, see golang/go#36699.
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}

	analysisDiagnostics, err := snapshot.Analyze(ctx, pkgIDs, tracker)
	if err != nil {
		return nil, err
	}
	return moremaps.Group(analysisDiagnostics, byURI), nil
}

// byURI is used for grouping diagnostics.
func byURI(d *cache.Diagnostic) protocol.DocumentURI { return d.URI }

// CombineDiagnostics combines and filters list/parse/type diagnostics from
// tdiags with the analysis adiags, returning the resulting combined set.
//
// Type-error analyzers produce diagnostics that are redundant with type
// checker diagnostics, but more detailed (e.g. fixes). Rather than report two
// diagnostics for the same problem, we combine them by augmenting the
// type-checker diagnostic and discarding the analyzer diagnostic.
//
// If an analysis diagnostic has the same range and message as a
// list/parse/type diagnostic, the suggested fix information (et al) of the
// latter is merged into a copy of the former. This handles the case where a
// type-error analyzer suggests a fix to a type error, and avoids duplication.
//
// The arguments are not modified.
func CombineDiagnostics(tdiags []*cache.Diagnostic, adiags []*cache.Diagnostic) []*cache.Diagnostic {
	// Build index of (list+parse+)type errors.
	type key struct {
		Range   protocol.Range
		message string
	}
	combined := make([]*cache.Diagnostic, len(tdiags))
	index := make(map[key]int) // maps (Range,Message) to index in tdiags slice
	for i, diag := range tdiags {
		index[key{diag.Range, diag.Message}] = i
		combined[i] = diag
	}

	// Filter out analysis diagnostics that match type errors,
	// retaining their suggested fix (etc) fields.
	for _, diag := range adiags {
		if i, ok := index[key{diag.Range, diag.Message}]; ok {
			copy := *tdiags[i]
			copy.SuggestedFixes = diag.SuggestedFixes
			copy.Tags = diag.Tags
			combined[i] = &copy
			continue
		}
		combined = append(combined, diag)
	}
	return combined
}


================================================
FILE: gopls/internal/golang/embeddirective.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"errors"
	"fmt"
	"io/fs"
	"path/filepath"
	"strconv"
	"strings"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/protocol"
)

// ErrNoEmbed is returned by EmbedDefinition when no embed
// directive is found at a particular position.
// As such it indicates that other definitions could be worth checking.
var ErrNoEmbed = errors.New("no embed directive found")

// embedDefinition finds a file matching the embed directive at pos in the mapped file.
// If there is no embed directive at pos, returns [ErrNoEmbed].
// If multiple files match the embed pattern, one is picked at random.
func embedDefinition(m *protocol.Mapper, rng protocol.Range) ([]protocol.Location, error) {
	pattern, _ := parseEmbedDirective(m, rng)
	if pattern == "" {
		return nil, ErrNoEmbed
	}
	pattern = filepath.FromSlash(pattern) // Match requires OS separators

	errFound := errors.New("found")

	// Find the first matching file.
	var match string
	dir := m.URI.DirPath()
	err := filepath.WalkDir(dir, func(abs string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}
		rel, err := filepath.Rel(dir, abs)
		if err != nil {
			return err
		}
		ok, err := filepath.Match(pattern, rel)
		if err != nil {
			return err
		}
		if ok && !d.IsDir() {
			match = abs
			return errFound
		}
		return nil
	})
	if err != nil && !errors.Is(err, errFound) {
		return nil, err // bad pattern or I/O error
	}
	if match == "" {
		return nil, fmt.Errorf("%q does not match any files in %q", pattern, dir)
	}
	return []protocol.Location{{URI: protocol.URIFromPath(match)}}, nil
}

// parseEmbedDirective attempts to parse a go:embed directive argument that
// contains the given range.
// If successful it returns the directive argument (a UNIX-style glob
// pattern) and its range, else zero values are returned.
func parseEmbedDirective(m *protocol.Mapper, rng protocol.Range) (string, protocol.Range) {
	if rng.Start.Line != rng.End.Line {
		return "", protocol.Range{}
	}

	lineStart, err := m.PositionOffset(protocol.Position{Line: rng.Start.Line, Character: 0})
	if err != nil {
		return "", protocol.Range{}
	}
	lineEnd, err := m.PositionOffset(protocol.Position{Line: rng.Start.Line + 1, Character: 0})
	if err != nil {
		return "", protocol.Range{}
	}

	text := string(m.Content[lineStart:lineEnd])
	if !strings.HasPrefix(text, "//go:embed") {
		return "", protocol.Range{}
	}
	text = text[len("//go:embed"):]
	offset := lineStart + len("//go:embed")

	// Find the first pattern in text that covers the offset of the pos we are looking for.
	startOffset, endOffset, err := m.RangeOffsets(rng)
	if err != nil {
		return "", protocol.Range{}
	}

	patterns, err := parseGoEmbed(text, offset)
	if err != nil {
		return "", protocol.Range{}
	}

	for _, p := range patterns {
		if p.startOffset <= startOffset && endOffset <= p.endOffset {
			// Found our match.
			rng, err := m.OffsetRange(p.startOffset, p.endOffset)
			if err != nil {
				return "", protocol.Range{}
			}
			return p.pattern, rng
		}
	}

	return "", protocol.Range{}
}

type fileEmbed struct {
	pattern     string
	startOffset int
	endOffset   int
}

// parseGoEmbed patterns that come after the directive.
//
// Copied and adapted from go/build/read.go.
// Replaced token.Position with start/end offset (including quotes if present).
func parseGoEmbed(args string, offset int) ([]fileEmbed, error) {
	trimBytes := func(n int) {
		offset += n
		args = args[n:]
	}
	trimSpace := func() {
		trim := strings.TrimLeftFunc(args, unicode.IsSpace)
		trimBytes(len(args) - len(trim))
	}

	var list []fileEmbed
	for trimSpace(); args != ""; trimSpace() {
		var path string
		pathOffset := offset
	Switch:
		switch args[0] {
		default:
			i := len(args)
			for j, c := range args {
				if unicode.IsSpace(c) {
					i = j
					break
				}
			}
			path = args[:i]
			trimBytes(i)

		case '`':
			var ok bool
			path, _, ok = strings.Cut(args[1:], "`")
			if !ok {
				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
			}
			trimBytes(1 + len(path) + 1)

		case '"':
			i := 1
			for ; i < len(args); i++ {
				if args[i] == '\\' {
					i++
					continue
				}
				if args[i] == '"' {
					q, err := strconv.Unquote(args[:i+1])
					if err != nil {
						return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args[:i+1])
					}
					path = q
					trimBytes(i + 1)
					break Switch
				}
			}
			if i >= len(args) {
				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
			}
		}

		if args != "" {
			r, _ := utf8.DecodeRuneInString(args)
			if !unicode.IsSpace(r) {
				return nil, fmt.Errorf("invalid quoted string in //go:embed: %s", args)
			}
		}
		list = append(list, fileEmbed{
			pattern:     path,
			startOffset: pathOffset,
			endOffset:   offset,
		})
	}
	return list, nil
}


================================================
FILE: gopls/internal/golang/extract.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/printer"
	"go/token"
	"go/types"
	"slices"
	"strconv"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
)

// extractVariableOne implements the refactor.extract.{variable,constant} CodeAction command.
func extractVariableOne(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	countExtractVariable.Inc()
	return extractVariable(pkg, pgf, start, end, false)
}

// extractVariableAll implements the refactor.extract.{variable,constant}-all CodeAction command.
func extractVariableAll(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	countExtractVariableAll.Inc()
	return extractVariable(pkg, pgf, start, end, true)
}

// extractVariable replaces one or all occurrences of a specified
// expression within the same function with newVar. If 'all' is true,
// it replaces all occurrences of the same expression; otherwise, it
// only replaces the selected expression.
//
// The new variable/constant is declared as close as possible to the first found expression
// within the deepest common scope accessible to all candidate occurrences.
func extractVariable(pkg *cache.Package, pgf *parsego.File, start, end token.Pos, all bool) (*token.FileSet, *analysis.SuggestedFix, error) {
	var (
		fset = pkg.FileSet()
		info = pkg.TypesInfo()
		file = pgf.File
	)
	curExprs, err := canExtractVariable(info, pgf.Cursor(), start, end, all)
	if err != nil {
		return nil, nil, fmt.Errorf("cannot extract: %v", err)
	}
	expr0 := curExprs[0].Node().(ast.Expr)

	// innermost scope enclosing ith expression
	exprScopes := make([]*types.Scope, len(curExprs))
	for i, curExpr := range curExprs {
		exprScopes[i] = info.Scopes[file].Innermost(curExpr.Node().Pos())
	}

	hasCollision := func(name string) bool {
		for _, scope := range exprScopes {
			if s, _ := scope.LookupParent(name, token.NoPos); s != nil {
				return true
			}
		}
		return false
	}
	constant := info.Types[expr0].Value != nil

	// Generate name(s) for new declaration.
	baseName := cond(constant, "newConst", "newVar")
	var lhsNames []string
	switch expr := expr0.(type) {
	case *ast.CallExpr:
		tup, ok := info.TypeOf(expr).(*types.Tuple)
		if !ok {
			// conversion or single-valued call:
			// treat it the same as our standard extract variable case.
			name, _ := generateName(0, baseName, hasCollision)
			lhsNames = append(lhsNames, name)

		} else {
			// call with multiple results
			idx := 0
			for range tup.Len() {
				// Generate a unique variable for each result.
				var name string
				name, idx = generateName(idx, baseName, hasCollision)
				lhsNames = append(lhsNames, name)
			}
		}

	default:
		// TODO: stricter rules for selectorExpr.
		name, _ := generateName(0, baseName, hasCollision)
		lhsNames = append(lhsNames, name)
	}

	// Where all the extractable positions can see variable being declared.
	var commonScope *types.Scope
	counter := make(map[*types.Scope]int)
Outer:
	for _, scope := range exprScopes {
		for s := scope; s != nil; s = s.Parent() {
			counter[s]++
			if counter[s] == len(exprScopes) {
				// A scope whose count is len(scopes) is common to all ancestor paths.
				// Stop at the first (innermost) one.
				commonScope = s
				break Outer
			}
		}
	}

	visible := curExprs[0] // Insert newVar inside commonScope before the first occurrence of the expression.
	if commonScope != exprScopes[0] {
		// This means the first expr within function body is not the largest scope,
		// we need to find the scope immediately follow the common
		// scope where we will insert the statement before.
		child := exprScopes[0]
		for p := child; p != nil; p = p.Parent() {
			if p == commonScope {
				break
			}
			child = p
		}
		visible, _ = pgf.Cursor().FindByPos(child.Pos(), child.End())
	}
	variables, err := collectFreeVars(info, file, expr0.Pos(), expr0.End(), expr0)
	if err != nil {
		return nil, nil, err
	}

	// TODO: There is a bug here: for a variable declared in a labeled
	// switch/for statement it returns the for/switch statement itself
	// which produces the below code which is a compiler error. e.g.
	//     label:
	//         switch r1 := r() { ... break label ... }
	// On extracting "r()" to a variable
	//     label:
	//         x := r()
	//         switch r1 := x { ... break label ... } // compiler error
	//
	var (
		insertPos   token.Pos
		indentation string
		stmtOK      bool // ok to use ":=" instead of var/const decl?
	)
	if funcDecl, _ := cursorutil.FirstEnclosing[*ast.FuncDecl](visible); funcDecl != nil &&
		astutil.NodeContainsPos(funcDecl.Body, start) {

		beforePos, err := stmtToInsertVarBefore(visible, variables)
		if err != nil {
			return nil, nil, fmt.Errorf("cannot find location to insert extraction: %v", err)
		}
		// Within function: compute appropriate statement indentation.
		indent, err := pgf.Indentation(beforePos)
		if err != nil {
			return nil, nil, err
		}
		insertPos = beforePos
		indentation = "\n" + indent

		// Currently, we always extract a constant expression
		// to a const declaration (and logic in CodeAction
		// assumes that we do so); this is conservative because
		// it preserves its constant-ness.
		//
		// In future, constant expressions used only in
		// contexts where constant-ness isn't important could
		// be profitably extracted to a var declaration or :=
		// statement, especially if the latter is the Init of
		// an {If,For,Switch}Stmt.
		stmtOK = !constant
	} else {
		// Outside any statement: insert before the current
		// top-level declaration, without indentation.
		for curDecl := range visible.Enclosing((*ast.FuncDecl)(nil), (*ast.GenDecl)(nil)) {
			insertPos = curDecl.Node().Pos()
		}
		indentation = "\n"
	}

	// Create statement to declare extracted var/const.
	//
	// TODO(adonovan): beware the const decls are not valid short
	// statements, so if fixing #70563 causes
	// StmtToInsertVarBefore to evolve to permit declarations in
	// the "pre" part of an IfStmt, like so:
	//   Before:
	//	if cond {
	//      } else if «1 + 2» > 0 {
	//      }
	//   After:
	//	if x := 1 + 2; cond {
	//      } else if x > 0 {
	//      }
	// then it will need to become aware that this is invalid
	// for constants.
	//
	// Conversely, a short var decl stmt is not valid at top level,
	// so when we fix #70665, we'll need to use a var decl.
	var newNode ast.Node
	if !stmtOK {
		// var/const x1, ..., xn = expr
		var names []*ast.Ident
		for _, name := range lhsNames {
			names = append(names, ast.NewIdent(name))
		}
		newNode = &ast.GenDecl{
			Tok: cond(constant, token.CONST, token.VAR),
			Specs: []ast.Spec{
				&ast.ValueSpec{
					Names:  names,
					Values: []ast.Expr{expr0},
				},
			},
		}

	} else {
		// var: x1, ... xn := expr
		var lhs []ast.Expr
		for _, name := range lhsNames {
			lhs = append(lhs, ast.NewIdent(name))
		}
		newNode = &ast.AssignStmt{
			Tok: token.DEFINE,
			Lhs: lhs,
			Rhs: []ast.Expr{expr0},
		}
	}

	// Format and indent the declaration.
	var buf bytes.Buffer
	if err := format.Node(&buf, fset, newNode); err != nil {
		return nil, nil, err
	}
	// TODO(adonovan): not sound for `...` string literals containing newlines.
	assignment := strings.ReplaceAll(buf.String(), "\n", indentation) + indentation
	textEdits := []analysis.TextEdit{{
		Pos:     insertPos,
		End:     insertPos,
		NewText: []byte(assignment),
	}}
	for _, curExpr := range curExprs {
		e := curExpr.Node()
		textEdits = append(textEdits, analysis.TextEdit{
			Pos:     e.Pos(),
			End:     e.End(),
			NewText: []byte(strings.Join(lhsNames, ", ")),
		})
	}
	return fset, &analysis.SuggestedFix{
		TextEdits: textEdits,
	}, nil
}

// stmtToInsertVarBefore returns the ast.Stmt before which we can safely insert a new variable,
// and ensures that the new declaration is inserted at a point where all free variables are declared before.
// Some examples:
//
// Basic Example:
//
//	z := 1
//	y := z + x
//
// If x is undeclared, then this function would return `y := z + x`, so that we
// can insert `x := ` on the line before `y := z + x`.
//
// valid IfStmt example:
//
//	if z == 1 {
//	} else if z == y {}
//
// If y is undeclared, then this function would return `if z == 1 {`, because we cannot
// insert a statement between an if and an else if statement. As a result, we need to find
// the top of the if chain to insert `y := ` before.
//
// invalid IfStmt example:
//
//	if x := 1; true {
//	} else if y := x + 1; true { //apply refactor.extract.variable to x
//	}
//
// `x` is a free variable defined in the IfStmt, we should not insert
// the extracted expression outside the IfStmt scope, instead, return an error.
func stmtToInsertVarBefore(cur inspector.Cursor, variables []*variable) (token.Pos, error) {
	// Walk up to enclosing statement.
	{
		var curStmt inspector.Cursor
		for cur := range cur.Enclosing() {
			if is[ast.Stmt](cur.Node()) {
				curStmt = cur
				break
			}
		}
		if !curStmt.Valid() {
			return 0, fmt.Errorf("no enclosing statement")
		}
		cur = curStmt
	}

	// hasFreeVar reports if any free variables is defined inside stmt (which may be nil).
	// If true, indicates that the insertion point will sit before the variable declaration.
	hasFreeVar := func(stmt ast.Stmt) bool {
		if stmt == nil {
			return false
		}
		for _, v := range variables {
			if astutil.NodeContainsPos(stmt, v.obj.Pos()) {
				return true
			}
		}
		return false
	}

	// baseIfStmt walks up the if/else-if chain until we get to
	// the top of the current if chain.
	baseIfStmt := func(curIf inspector.Cursor) (token.Pos, error) {
		for curIf.ParentEdgeKind() == edge.IfStmt_Else {
			curIf = curIf.Parent()
			if hasFreeVar(curIf.Node().(*ast.IfStmt).Init) {
				return 0, fmt.Errorf("else-if's init has free variable")
			}
		}
		return curIf.Node().Pos(), nil
	}

	stmt := cur.Node()
	switch stmt := stmt.(type) {
	case *ast.IfStmt:
		if hasFreeVar(stmt.Init) {
			return 0, fmt.Errorf("if statement's init has free variable")
		}
		// stmt is inside of the if declaration.
		// We need to check if we are in an else-if stmt and
		// get the base if statement.
		return baseIfStmt(cur)

	case *ast.CaseClause:
		for curSwitch := range cur.Enclosing((*ast.SwitchStmt)(nil), (*ast.TypeSwitchStmt)(nil)) {
			swtch := curSwitch.Node()
			var init ast.Stmt
			switch swtch := swtch.(type) {
			case *ast.SwitchStmt:
				init = swtch.Init
			case *ast.TypeSwitchStmt:
				init = swtch.Init
			}
			if hasFreeVar(init) {
				return 0, fmt.Errorf("switch's init has free variable")
			}
			return swtch.Pos(), nil
		}
	}

	// Check if the enclosing statement is inside another node.
	switch parent := cur.Parent().Node().(type) {
	case *ast.IfStmt:
		if hasFreeVar(parent.Init) {
			return 0, fmt.Errorf("if-statement's init has free variable")
		}
		return baseIfStmt(cur.Parent())

	case *ast.ForStmt:
		switch cur.Node() {
		case parent.Init, parent.Post:
			return parent.Pos(), nil
		}

	case *ast.SwitchStmt:
		if hasFreeVar(parent.Init) {
			return 0, fmt.Errorf("switch's init has free variable")
		}
		return parent.Pos(), nil

	case *ast.TypeSwitchStmt:
		if hasFreeVar(parent.Init) {
			return 0, fmt.Errorf("switch's init has free variable")
		}
		return parent.Pos(), nil
	}
	return stmt.Pos(), nil
}

// canExtractVariable reports whether the code in the given range can
// be extracted to a variable (or constant). It returns (cursors for)
// the selected expression or, if 'all', all structurally equivalent
// expressions within the same function body, in lexical order.
func canExtractVariable(info *types.Info, curFile inspector.Cursor, start, end token.Pos, all bool) ([]inspector.Cursor, error) {
	if start == end {
		return nil, fmt.Errorf("empty selection")
	}

	_, curStart, curEnd, err := astutil.Select(curFile, start, end)
	if err != nil {
		return nil, err
	}
	expr, ok := curStart.Node().(ast.Expr)
	if !ok || curEnd != curStart {
		return nil, fmt.Errorf("selection is not an expression")
	}
	if imp, _ := cursorutil.FirstEnclosing[*ast.ImportSpec](curStart); imp != nil {
		return nil, fmt.Errorf("cannot extract variable or constant in an import block")
	}
	if tv, ok := info.Types[expr]; !ok || !tv.IsValue() || tv.Type == nil || tv.HasOk() {
		// e.g. type, builtin, x.(type), 2-valued m[k], or ill-typed
		return nil, fmt.Errorf("selection is not a single-valued expression")
	}

	var curExprs []inspector.Cursor
	if !all {
		curExprs = append(curExprs, curStart)
	} else if funcDecl, curFuncDecl := cursorutil.FirstEnclosing[*ast.FuncDecl](curStart); funcDecl != nil && funcDecl.Body != nil {
		// Find all expressions in the same function body that
		// are equal to the selected expression.
		for cur := range curFuncDecl.ChildAt(edge.FuncDecl_Body, -1).Preorder() {
			if e, ok := cur.Node().(ast.Expr); ok {
				if astutil.Equal(e, expr, func(x, y *ast.Ident) bool {
					xobj, yobj := info.ObjectOf(x), info.ObjectOf(y)
					// The two identifiers must resolve to the same object,
					// or to a declaration within the candidate expression.
					// (This allows two copies of "func (x int) { print(x) }"
					// to match.)
					if xobj != nil && astutil.NodeContainsPos(e, xobj.Pos()) &&
						yobj != nil && astutil.NodeContainsPos(expr, yobj.Pos()) {
						return x.Name == y.Name
					}
					// Use info.Uses to avoid including declaration, for example,
					// when extractnig x:
					//
					//   x := 1 // should not include x
					//   y := x // include x
					//   z := x // include x
					xuse := info.Uses[x]
					return xuse != nil && xuse == info.Uses[y]
				}) {
					curExprs = append(curExprs, cur)
				}
			}
		}
	} else {
		return nil, fmt.Errorf("node %T is not inside a function", expr)
	}

	// Disallow any expr that sits in lhs of an AssignStmt or ValueSpec for now.
	//
	// TODO(golang/go#70784): In such cases, exprs are operated in "variable" mode (L-value mode in C).
	// In contrast, exprs in the RHS operate in "value" mode (R-value mode in C).
	// L-value mode refers to exprs that represent storage locations,
	// while R-value mode refers to exprs that represent values.
	// There are a number of expressions that may have L-value mode, given by:
	//
	//   lvalue = ident                -- Ident such that info.Uses[id] is a *Var
	//          | '(' lvalue ') '      -- ParenExpr
	//          | lvalue '[' expr ']'  -- IndexExpr
	//          | lvalue '.' ident     -- SelectorExpr.
	//
	// For example:
	//
	//   type foo struct {
	//       bar int
	//   }
	//   f := foo{bar: 1}
	//   x := f.bar + 1 // f.bar operates in "value" mode.
	//   f.bar = 2      // f.bar operates in "variable" mode.
	//
	// When extracting exprs in variable mode, we must be cautious. Any such extraction
	// may require capturing the address of the expression and replacing its uses with dereferenced access.
	// The type checker records this information in info.Types[id].{IsValue,Addressable}().
	// The correct result should be:
	//
	//   newVar := &f.bar
	//   x := *newVar + 1
	//   *newVar = 2
	for _, curExpr := range curExprs {
		switch curExpr.ParentEdgeKind() {
		case edge.AssignStmt_Lhs:
			return nil, fmt.Errorf("node %T is in LHS of an AssignStmt", expr)
		case edge.ValueSpec_Names:
			return nil, fmt.Errorf("node %T is in LHS of a ValueSpec", expr)
		}
	}

	return curExprs, nil
}

// freshName returns an identifier based on prefix (perhaps with a
// numeric suffix) that is not in scope at the specified position
// within the file. It returns the next numeric suffix to use.
func freshName(info *types.Info, file *ast.File, pos token.Pos, prefix string, idx int) (string, int) {
	scope := info.Scopes[file].Innermost(pos)
	return generateName(idx, prefix, func(name string) bool {
		obj, _ := scope.LookupParent(name, pos)
		return obj != nil
	})
}

// freshNameOutsideRange is like [freshName], but ignores names
// declared between start and end for the purposes of detecting conflicts.
//
// This is used for function extraction, where [start, end) will be extracted
// to a new scope.
func freshNameOutsideRange(info *types.Info, file *ast.File, pos, start, end token.Pos, prefix string, idx int) (string, int) {
	scope := info.Scopes[file].Innermost(pos)
	return generateName(idx, prefix, func(name string) bool {
		// Only report a collision if the object declaration
		// was outside the extracted range.
		for scope != nil {
			obj, declScope := scope.LookupParent(name, pos)
			if obj == nil {
				return false // undeclared
			}
			if !(start <= obj.Pos() && obj.Pos() < end) {
				return true // declared outside ignored range
			}
			scope = declScope.Parent()
		}
		return false
	})
}

func generateName(idx int, prefix string, hasCollision func(string) bool) (string, int) {
	name := prefix
	if idx != 0 {
		name += fmt.Sprintf("%d", idx)
	}
	for hasCollision(name) {
		idx++
		name = fmt.Sprintf("%v%d", prefix, idx)
	}
	return name, idx + 1
}

// returnVariable keeps track of the information we need to properly introduce a new variable
// that we will return in the extracted function.
type returnVariable struct {
	// name is the identifier that is used on the left-hand side of the call to
	// the extracted function.
	name *ast.Ident
	// decl is the declaration of the variable. It is used in the type signature of the
	// extracted function and for variable declarations.
	decl *ast.Field
	// zeroVal is the "zero value" of the type of the variable. It is used in a return
	// statement in the extracted function.
	zeroVal ast.Expr
}

// extractMethod refactors the selected block of code into a new method.
func extractMethod(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	countExtractMethod.Inc()
	return extractFunctionMethod(pkg, pgf, start, end, true)
}

// extractFunction refactors the selected block of code into a new function.
func extractFunction(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	countExtractFunction.Inc()
	return extractFunctionMethod(pkg, pgf, start, end, false)
}

// extractFunctionMethod refactors the selected block of code into a new function/method.
// It also replaces the selected block of code with a call to the extracted
// function. First, we manually adjust the selection range. We remove trailing
// and leading whitespace characters to ensure the range is precisely bounded
// by AST nodes. Next, we determine the variables that will be the parameters
// and return values of the extracted function/method. Lastly, we construct the call
// of the function/method and insert this call as well as the extracted function/method into
// their proper locations.
func extractFunctionMethod(cpkg *cache.Package, pgf *parsego.File, start, end token.Pos, isMethod bool) (*token.FileSet, *analysis.SuggestedFix, error) {
	var (
		fset = cpkg.FileSet()
		pkg  = cpkg.Types()
		info = cpkg.TypesInfo()
		src  = pgf.Src
		file = pgf.File
	)

	errorPrefix := "extractFunction"
	if isMethod {
		errorPrefix = "extractMethod"
	}

	p, ok, methodOk, err := canExtractFunction(pgf.Cursor(), start, end)
	if (!ok && !isMethod) || (!methodOk && isMethod) {
		return nil, nil, fmt.Errorf("%s: cannot extract %s: %v", errorPrefix,
			safetoken.StartPosition(fset, start), err)
	}
	curEnclosing, curStart, curEnd, curFuncDecl := p.curEnclosing, p.curStart, p.curEnd, p.curFuncDecl

	// Narrow (start, end) to the located nodes.
	start, end = curStart.Node().Pos(), curEnd.Node().End()
	outer := curFuncDecl.Node().(*ast.FuncDecl)

	// Labeled statements have un-intuitive ranges.
	// Technically they end at the end of the statement
	// that they label, but user expectation is that the label
	// is a pseudo-statement by itself. This is especially confusing when
	// the statement that's labeled is a multi-line block statement.
	//
	// If the end cursor is the identifier in a labeled statement,
	// we expand the range to include the colon.
	// That way, we include the label, but not the statement being labeled
	if curEnd.ParentEdgeKind() == edge.LabeledStmt_Label {
		end = curEnd.Parent().Node().(*ast.LabeledStmt).Colon + 1
	}

	// A return statement is non-nested if its parent node is equal to the parent node
	// of the first node in the selection. These cases must be handled separately because
	// non-nested return statements are guaranteed to execute.
	var hasNonNestedReturn bool

	// Determine whether all return statements in the selection are
	// error-handling return statements. They must be of the form:
	// if err != nil {
	// 	return ..., err
	// }
	// If all return statements in the extracted block have a non-nil error, we
	// can replace the "shouldReturn" check with an error check to produce a
	// more concise output.
	var (
		allReturnsFinalErr = true  // all ReturnStmts have final 'err' expression
		hasReturn          = false // selection contains a ReturnStmt
		filter             = []ast.Node{(*ast.ReturnStmt)(nil), (*ast.FuncLit)(nil)}
	)
	curEnclosing.Inspect(filter, func(cur inspector.Cursor) (descend bool) {
		if funcLit, ok := cur.Node().(*ast.FuncLit); ok {
			// Exclude return statements in function literals because they don't affect the refactor.
			// Keep descending into func lits whose declaration is not included in the extracted block.
			return !(start < funcLit.Pos() && funcLit.End() < end)
		}
		ret := cur.Node().(*ast.ReturnStmt)
		if ret.Pos() < start || ret.End() > end {
			return false // not part of the extracted block
		}
		hasReturn = true

		if cur.Parent() == curStart.Parent() {
			hasNonNestedReturn = true
		}

		if !allReturnsFinalErr {
			// Stop the traversal if we have already found a non error-handling return statement.
			return false
		}
		// Check if the return statement returns a non-nil error as the last value.
		if len(ret.Results) > 0 {
			typ := info.TypeOf(ret.Results[len(ret.Results)-1])
			if typ != nil && types.Identical(typ, errorType) {
				// Have: return ..., err
				// Check for enclosing "if err != nil { return ..., err }".
				// In that case, we can lift the error return to the caller.
				if ifstmt, ok := cur.Parent().Parent().Node().(*ast.IfStmt); ok {
					// Only handle the case where the if statement body contains a single statement.
					if body, ok := cur.Parent().Node().(*ast.BlockStmt); ok && len(body.List) <= 1 {
						if cond, ok := ifstmt.Cond.(*ast.BinaryExpr); ok {
							tx := info.TypeOf(cond.X)
							ty := info.TypeOf(cond.Y)
							isErr := tx != nil && types.Identical(tx, errorType)
							isNil := ty != nil && types.Identical(ty, types.Typ[types.UntypedNil])
							if cond.Op == token.NEQ && isErr && isNil {
								// allReturnsErrHandling remains true
								return false
							}
						}
					}
				}
			}
		}
		allReturnsFinalErr = false
		return false
	})

	allReturnsFinalErr = hasReturn && allReturnsFinalErr

	// Now that we have determined the correct range for the selection block,
	// we must determine the signature of the extracted function. We will then replace
	// the block with an assignment statement that calls the extracted function with
	// the appropriate parameters and return values.
	variables, err := collectFreeVars(info, file, start, end, curEnclosing.Node())
	if err != nil {
		return nil, nil, err
	}

	var (
		receiverUsed bool
		receiver     *ast.Field
		receiverName string
		receiverObj  types.Object
	)
	if isMethod {
		if outer.Recv == nil || len(outer.Recv.List) == 0 {
			return nil, nil, fmt.Errorf("%s: cannot extract need method receiver", errorPrefix)
		}
		receiver = outer.Recv.List[0]
		if len(receiver.Names) == 0 || receiver.Names[0] == nil {
			return nil, nil, fmt.Errorf("%s: cannot extract need method receiver name", errorPrefix)
		}
		recvName := receiver.Names[0]
		receiverName = recvName.Name
		receiverObj = info.ObjectOf(recvName)
	}

	var (
		params, returns         []ast.Expr     // used when calling the extracted function
		paramTypes, returnTypes []*ast.Field   // used in the signature of the extracted function
		uninitialized           []types.Object // vars we will need to initialize before the call
	)

	// Avoid duplicates while traversing vars and uninitialized.
	seenVars := make(map[types.Object]ast.Expr)
	seenUninitialized := make(map[types.Object]struct{})

	// Some variables on the left-hand side of our assignment statement may be free. If our
	// selection begins in the same scope in which the free variable is defined, we can
	// redefine it in our assignment statement. See the following example, where 'b' and
	// 'err' (both free variables) can be redefined in the second funcCall() while maintaining
	// correctness.
	//
	//
	// Not Redefined:
	//
	// a, err := funcCall()
	// var b int
	// b, err = funcCall()
	//
	// Redefined:
	//
	// a, err := funcCall()
	// b, err := funcCall()
	//
	// We track the number of free variables that can be redefined to maintain our preference
	// of using "x, y, z := fn()" style assignment statements.
	var canRedefineCount int

	qual := typesinternal.FileQualifier(file, pkg)

	// Each identifier in the selected block must become (1) a parameter to the
	// extracted function, (2) a return value of the extracted function, or (3) a local
	// variable in the extracted function. Determine the outcome(s) for each variable
	// based on whether it is free, altered within the selected block, and used outside
	// of the selected block.
	for _, v := range variables {
		if _, ok := seenVars[v.obj]; ok {
			continue
		}
		if v.obj.Name() == "_" {
			// The blank identifier is always a local variable
			continue
		}
		typ := typesinternal.TypeExpr(v.obj.Type(), qual)
		seenVars[v.obj] = typ
		identifier := ast.NewIdent(v.obj.Name())
		// An identifier must meet three conditions to become a return value of the
		// extracted function. (1) its value must be defined or reassigned within
		// the selection (isAssigned), (2) it must be used at least once after the
		// selection (isUsed), and (3) its first use after the selection
		// cannot be its own reassignment or redefinition (objOverriden).
		vscope := v.obj.Parent()
		if vscope == nil {
			// v.obj could be a field on an anonymous struct. We'll examine the
			// struct in a different iteration so don't return an error here.
			continue
		}
		isUsed, firstUseAfter := objUsed(info, end, vscope.End(), v.obj)
		if v.assigned && isUsed && !varOverridden(info, firstUseAfter, v.obj, v.free, outer) {
			returnTypes = append(returnTypes, &ast.Field{Type: typ})
			returns = append(returns, identifier)
			if !v.free {
				uninitialized = append(uninitialized, v.obj)

			} else {
				// In go1.22, Scope.Pos for function scopes changed (#60752):
				// it used to start at the body ('{'), now it starts at "func".
				//
				// The second condition below handles the case when
				// v's block is the FuncDecl.Body itself.
				startParent := curStart.Parent().Node()
				if vscope.Pos() == startParent.Pos() ||
					startParent == outer.Body && vscope == info.Scopes[outer.Type] {
					canRedefineCount++
				}
			}
		}
		// An identifier must meet two conditions to become a parameter of the
		// extracted function. (1) it must be free (isFree), and (2) its first
		// use within the selection cannot be its own definition (isDefined).
		if v.free && !v.defined {
			// Skip the selector for a method.
			if isMethod && v.obj == receiverObj {
				receiverUsed = true
				continue
			}
			params = append(params, identifier)
			paramTypes = append(paramTypes, &ast.Field{
				Names: []*ast.Ident{identifier},
				Type:  typ,
			})
		}
	}

	reorderParams(params, paramTypes)

	// Find the function literal that encloses the selection. The enclosing function literal
	// may not be the enclosing function declaration (i.e. 'outer'). For example, in the
	// following block:
	//
	// func main() {
	//     ast.Inspect(node, func(n ast.Node) bool {
	//         v := 1 // this line extracted
	//         return true
	//     })
	// }
	//
	// 'outer' is main(). However, the extracted selection most directly belongs to
	// the anonymous function literal, the second argument of ast.Inspect(). We use the
	// enclosing function literal to determine the proper return types for return statements
	// within the selection. We still need the enclosing function declaration because this is
	// the top-level declaration. We inspect the top-level declaration to look for variables
	// as well as for code replacement.
	enclosing := outer.Type
	if funcLit, _ := cursorutil.FirstEnclosing[*ast.FuncLit](curEnclosing); funcLit != nil {
		enclosing = funcLit.Type
	}

	// We put the selection in a constructed file. We can then traverse and edit
	// the extracted selection without modifying the original AST.
	startOffset, endOffset, err := safetoken.Offsets(pgf.Tok, start, end)
	if err != nil {
		return nil, nil, err
	}
	selection := src[startOffset:endOffset]

	extractedBlock, extractedComments, err := parseStmts(fset, selection)
	if err != nil {
		return nil, nil, err
	}

	// We need to account for return statements in the selected block, as they will complicate
	// the logical flow of the extracted function. See the following example, where ** denotes
	// the range to be extracted.
	//
	// Before:
	//
	// func _() int {
	//     a := 1
	//     b := 2
	//     **if a == b {
	//         return a
	//     }**
	//     ...
	// }
	//
	// After:
	//
	// func _() int {
	//     a := 1
	//     b := 2
	//     cond0, ret0 := x0(a, b)
	//     if cond0 {
	//         return ret0
	//     }
	//     ...
	// }
	//
	// func x0(a int, b int) (bool, int) {
	//     if a == b {
	//         return true, a
	//     }
	//     return false, 0
	// }
	//
	// We handle returns by adding an additional boolean return value to the extracted function.
	// This bool reports whether the original function would have returned. Because the
	// extracted selection contains a return statement, we must also add the types in the
	// return signature of the enclosing function to the return signature of the
	// extracted function. We then add an extra if statement checking this boolean value
	// in the original function. If the condition is met, the original function should
	// return a value, mimicking the functionality of the original return statement(s)
	// in the selection.
	//
	// If there is a return that is guaranteed to execute (hasNonNestedReturns=true), then
	// we don't need to include this additional condition check and can simply return.
	//
	// Before:
	//
	// func _() int {
	//     a := 1
	//     b := 2
	//     **if a == b {
	//         return a
	//     }
	//	   return b**
	// }
	//
	// After:
	//
	// func _() int {
	//     a := 1
	//     b := 2
	//     return x0(a, b)
	// }
	//
	// func x0(a int, b int) int {
	//     if a == b {
	//         return a
	//     }
	//     return b
	// }

	var retVars []*returnVariable
	var ifReturn *ast.IfStmt

	// Determine if the extracted block contains any free branch statements, for
	// example: "continue label" where "label" is declared outside of the
	// extracted block, or continue inside a "for" statement where the for
	// statement is declared outside of the extracted block. These will be
	// handled below, after adjusting return statements and generating return
	// info.
	curSel, _ := pgf.Cursor().FindByPos(start, end) // since canExtractFunction succeeded, this will always return a valid cursor
	freeBranches := freeBranches(info, curSel, start, end)

	// All return statements in the extracted block are error handling returns, and there are no free control statements.
	isErrHandlingReturnsCase := allReturnsFinalErr && len(freeBranches) == 0

	if hasReturn {
		if !hasNonNestedReturn {
			// The selected block contained return statements, so we have to modify the
			// signature of the extracted function as described above. Adjust all of
			// the return statements in the extracted function to reflect this change in
			// signature.
			if err := adjustReturnStatements(returnTypes, seenVars, extractedBlock, qual, isErrHandlingReturnsCase); err != nil {
				return nil, nil, err
			}
		}
		// Collect the additional return values and types needed to accommodate return
		// statements in the selection. Update the type signature of the extracted
		// function and construct the if statement that will be inserted in the enclosing
		// function.
		retVars, ifReturn, err = generateReturnInfo(enclosing, pkg, curEnclosing.Node().Pos(), file, info, start, end, hasNonNestedReturn, isErrHandlingReturnsCase)
		if err != nil {
			return nil, nil, err
		}
	}

	// If the extracted block contains free branch statements, we add another
	// return value "ctrl" to the extracted function that will be used to
	// determine the control flow. See the following example, where === denotes
	// the range to be extracted.
	//
	// Before:
	// func f(cond bool) {
	//      for range "abc" {
	//      ==============
	//      if cond {
	//          continue
	//      }
	//      ==============
	//      println(0)
	//      }
	// }

	// After:
	// func f(cond bool) {
	//      for range "abc" {
	//      ctrl := newFunction(cond)
	//      switch ctrl {
	//      case 1:
	//          continue
	//      }
	//      println(0)
	//      }
	// }
	//
	// func newFunction(cond bool) int {
	//      if cond {
	//          return 1
	//      }
	//      return 0
	// }
	//

	// Generate an unused identifier for the control value.
	ctrlVar, _ := freshName(info, file, start, "ctrl", 0)
	if len(freeBranches) > 0 {

		zeroValExpr := &ast.BasicLit{
			Kind:  token.INT,
			Value: "0",
		}
		var branchStmts []*ast.BranchStmt
		// Add the zero "ctrl" value to each return statement in the extracted block.
		ast.PreorderStack(extractedBlock, nil, func(n ast.Node, stack []ast.Node) bool {
			switch n := n.(type) {
			case *ast.ReturnStmt:
				n.Results = append(n.Results, zeroValExpr)
			case *ast.BranchStmt:
				// Collect a list of branch statements in the extracted block to examine later.
				if isFreeBranchStmt(append(stack, n), extractedBlock) {
					branchStmts = append(branchStmts, n)
				}
			case *ast.FuncLit:
				// Don't descend into nested functions.
				return false
			}
			return true
		})

		// Construct a return statement to replace each free branch statement in the extracted block. It should have
		// zero values for all return parameters except one, "ctrl", which dictates which continuation to follow.
		var freeCtrlStmtReturns []ast.Expr
		// Create "zero values" for each type.
		for _, returnType := range returnTypes {
			var val ast.Expr
			var isValid bool
			for obj, typ := range seenVars {
				if typ == returnType.Type {
					val, isValid = typesinternal.ZeroExpr(obj.Type(), qual)
					break
				}
			}
			if !isValid {
				return nil, nil, fmt.Errorf("could not find matching AST expression for %T", returnType.Type)
			}
			freeCtrlStmtReturns = append(freeCtrlStmtReturns, val)
		}
		freeCtrlStmtReturns = append(freeCtrlStmtReturns, getZeroVals(retVars)...)

		for i, branchStmt := range branchStmts {
			replaceBranchStmtWithReturnStmt(extractedBlock, branchStmt, &ast.ReturnStmt{
				Return: branchStmt.Pos(),
				Results: append(slices.Clip(freeCtrlStmtReturns), &ast.BasicLit{
					Kind:  token.INT,
					Value: strconv.Itoa(i + 1), // start with 1 because 0 is reserved for base case
				}),
			})

		}
		retVars = append(retVars, &returnVariable{
			name:    ast.NewIdent(ctrlVar),
			decl:    &ast.Field{Type: ast.NewIdent("int")},
			zeroVal: zeroValExpr,
		})
	}

	// Add a return statement to the end of the new function. This return statement must include
	// the values for the types of the original extracted function signature and (if a return
	// statement is present in the selection) enclosing function signature.
	// This only needs to be done if the selections does not have a non-nested return, otherwise
	// it already terminates with a return statement.
	hasReturnValues := len(returns)+len(retVars) > 0
	if hasReturnValues && !hasNonNestedReturn {
		extractedBlock.List = append(extractedBlock.List, &ast.ReturnStmt{
			Results: append(returns, getZeroVals(retVars)...),
		})
	}

	// Construct the appropriate call to the extracted function.
	// We must meet two conditions to use ":=" instead of '='. (1) there must be at least
	// one variable on the lhs that is uninitialized (non-free) prior to the assignment.
	// (2) all of the initialized (free) variables on the lhs must be able to be redefined.
	sym := token.ASSIGN
	canDefineCount := len(uninitialized) + canRedefineCount
	canDefine := len(uninitialized)+len(retVars) > 0 && canDefineCount == len(returns)
	if canDefine {
		sym = token.DEFINE
	}
	var funName string
	if isMethod {
		// TODO(suzmue): generate a name that does not conflict for "newMethod".
		funName = "newMethod"
	} else {
		funName, _ = freshName(info, file, start, "newFunction", 0)
	}
	extractedFunCall := generateFuncCall(hasNonNestedReturn, hasReturnValues, params,
		append(returns, getNames(retVars)...), funName, sym, receiverName)

	// Create variable declarations for any identifiers that need to be initialized prior to
	// calling the extracted function. We do not manually initialize variables if every return
	// value is uninitialized. We can use := to initialize the variables in this situation.
	var declarations []ast.Stmt
	if canDefineCount != len(returns) {
		declarations = initializeVars(uninitialized, retVars, seenUninitialized, seenVars)
	}

	var declBuf, replaceBuf, newFuncBuf, ifBuf, commentBuf bytes.Buffer
	if err := format.Node(&declBuf, fset, declarations); err != nil {
		return nil, nil, err
	}
	if err := format.Node(&replaceBuf, fset, extractedFunCall); err != nil {
		return nil, nil, err
	}
	if ifReturn != nil {
		if isErrHandlingReturnsCase {
			errName := retVars[len(retVars)-1]
			fmt.Fprintf(&ifBuf, "if %s != nil ", errName.name.String())
			if err := format.Node(&ifBuf, fset, ifReturn.Body); err != nil {
				return nil, nil, err
			}
		} else {
			if err := format.Node(&ifBuf, fset, ifReturn); err != nil {
				return nil, nil, err
			}
		}
	}

	// Build the extracted function. We format the function declaration and body
	// separately, so that comments are printed relative to the extracted
	// BlockStmt.
	//
	// In other words, extractedBlock and extractedComments were parsed from a
	// synthetic function declaration of the form func _() { ... }. If we now
	// print the real function declaration, the length of the signature will have
	// grown, causing some comment positions to be computed as inside the
	// signature itself.
	newFunc := &ast.FuncDecl{
		Name: ast.NewIdent(funName),
		Type: &ast.FuncType{
			Params:  &ast.FieldList{List: paramTypes},
			Results: &ast.FieldList{List: append(returnTypes, getDecls(retVars)...)},
		},
		// Body handled separately -- see above.
	}
	if isMethod {
		var names []*ast.Ident
		if receiverUsed {
			names = append(names, ast.NewIdent(receiverName))
		}
		newFunc.Recv = &ast.FieldList{
			List: []*ast.Field{{
				Names: names,
				Type:  receiver.Type,
			}},
		}
	}
	if err := format.Node(&newFuncBuf, fset, newFunc); err != nil {
		return nil, nil, err
	}
	// Write a space between the end of the function signature and opening '{'.
	if err := newFuncBuf.WriteByte(' '); err != nil {
		return nil, nil, err
	}
	commentedNode := &printer.CommentedNode{
		Node:     extractedBlock,
		Comments: extractedComments,
	}
	if err := format.Node(&newFuncBuf, fset, commentedNode); err != nil {
		return nil, nil, err
	}

	// We're going to replace the whole enclosing function,
	// so preserve the text before and after the selected block.
	outerStart, outerEnd, err := pgf.NodeOffsets(outer)
	if err != nil {
		return nil, nil, err
	}
	before := src[outerStart:startOffset]
	after := src[endOffset:outerEnd]
	indent, err := pgf.Indentation(start)
	if err != nil {
		return nil, nil, err
	}
	newLineIndent := "\n" + indent

	var fullReplacement strings.Builder
	fullReplacement.Write(before)
	if commentBuf.Len() > 0 {
		comments := strings.ReplaceAll(commentBuf.String(), "\n", newLineIndent)
		fullReplacement.WriteString(comments)
	}
	if declBuf.Len() > 0 { // add any initializations, if needed
		initializations := strings.ReplaceAll(declBuf.String(), "\n", newLineIndent) +
			newLineIndent
		fullReplacement.WriteString(initializations)
	}
	fullReplacement.Write(replaceBuf.Bytes()) // call the extracted function
	if ifBuf.Len() > 0 {                      // add the if statement below the function call, if needed
		ifstatement := newLineIndent +
			strings.ReplaceAll(ifBuf.String(), "\n", newLineIndent)
		fullReplacement.WriteString(ifstatement)
	}

	// Add the switch statement for free branch statements after the new function call.
	if len(freeBranches) > 0 {
		fmt.Fprintf(&fullReplacement, "%[1]sswitch %[2]s {%[1]s", newLineIndent, ctrlVar)
		for i, br := range freeBranches {
			// Preserve spacing at the beginning of the line containing the branch statement.
			startPos := pgf.Tok.LineStart(safetoken.Line(pgf.Tok, br.Pos()))
			text, err := pgf.PosText(startPos, br.End())
			if err != nil {
				return nil, nil, err
			}
			fmt.Fprintf(&fullReplacement, "case %d:\n%s%s", i+1, text, newLineIndent)
		}
		fullReplacement.WriteString("}")
	}

	fullReplacement.Write(after)
	fullReplacement.WriteString("\n\n")       // add newlines after the enclosing function
	fullReplacement.Write(newFuncBuf.Bytes()) // insert the extracted function

	return fset, &analysis.SuggestedFix{
		TextEdits: []analysis.TextEdit{{
			Pos:     outer.Pos(),
			End:     outer.End(),
			NewText: []byte(fullReplacement.String()),
		}},
	}, nil
}

// isSelector reports if e is the selector expr <x>, <sel>. It works for pointer and non-pointer selector expressions.
func isSelector(e ast.Expr, x, sel string) bool {
	unary, ok := e.(*ast.UnaryExpr)
	if ok && unary.Op == token.MUL {
		e = unary.X
	}
	selectorExpr, ok := e.(*ast.SelectorExpr)
	if !ok {
		return false
	}
	ident, ok := selectorExpr.X.(*ast.Ident)
	if !ok {
		return false
	}
	return ident.Name == x && selectorExpr.Sel.Name == sel
}

// reorderParams reorders the given parameters in-place to follow common Go conventions.
func reorderParams(params []ast.Expr, paramTypes []*ast.Field) {
	moveParamToFrontIfFound(params, paramTypes, "testing", "T")
	moveParamToFrontIfFound(params, paramTypes, "testing", "B")
	moveParamToFrontIfFound(params, paramTypes, "context", "Context")
}

func moveParamToFrontIfFound(params []ast.Expr, paramTypes []*ast.Field, x, sel string) {
	// Move Context parameter (if any) to front.
	for i, t := range paramTypes {
		if isSelector(t.Type, x, sel) {
			p, t := params[i], paramTypes[i]
			copy(params[1:], params[:i])
			copy(paramTypes[1:], paramTypes[:i])
			params[0], paramTypes[0] = p, t
			break
		}
	}
}

// variable describes the status of a variable within a selection.
type variable struct {
	obj types.Object

	// free reports whether the variable is a free variable, meaning it should
	// be a parameter to the extracted function.
	free bool

	// assigned reports whether the variable is assigned to in the selection.
	assigned bool

	// defined reports whether the variable is defined in the selection.
	defined bool
}

// collectFreeVars maps each identifier in the given range to whether it is "free."
// Given a range, a variable in that range is defined as "free" if it is declared
// outside of the range and neither at the file scope nor package scope. These free
// variables will be used as arguments in the extracted function. It also returns a
// list of identifiers that may need to be returned by the extracted function.
// Some of the code in this function has been adapted from tools/cmd/guru/freevars.go.
func collectFreeVars(info *types.Info, file *ast.File, start, end token.Pos, node ast.Node) ([]*variable, error) {
	fileScope := info.Scopes[file]
	if fileScope == nil {
		return nil, bug.Errorf("file scope is empty")
	}
	pkgScope := fileScope.Parent()
	if pkgScope == nil {
		return nil, bug.Errorf("package scope is empty")
	}
	// id returns non-nil if n denotes an object that is referenced by the span
	// and defined either within the span or in the lexical environment. The bool
	// return value acts as an indicator for where it was defined.
	id := func(n *ast.Ident) (types.Object, bool) {
		obj := info.Uses[n]
		if obj == nil {
			return info.Defs[n], false
		}
		if obj.Name() == "_" {
			return nil, false // exclude objects denoting '_'
		}
		if _, ok := obj.(*types.PkgName); ok {
			return nil, false // imported package
		}
		if !(file.FileStart <= obj.Pos() && obj.Pos() <= file.FileEnd) {
			return nil, false // not defined in this file
		}
		scope := obj.Parent()
		if scope == nil {
			return nil, false // e.g. interface method, struct field
		}
		if scope == fileScope || scope == pkgScope {
			return nil, false // defined at file or package scope
		}
		if start <= obj.Pos() && obj.Pos() <= end {
			return obj, false // defined within selection => not free
		}
		return obj, true
	}
	// sel returns non-nil if n denotes a selection o.x.y that is referenced by the
	// span and defined either within the span or in the lexical environment. The bool
	// return value acts as an indicator for where it was defined.
	var sel func(n *ast.SelectorExpr) (types.Object, bool)
	sel = func(n *ast.SelectorExpr) (types.Object, bool) {
		switch x := ast.Unparen(n.X).(type) {
		case *ast.SelectorExpr:
			return sel(x)
		case *ast.Ident:
			return id(x)
		}
		return nil, false
	}
	seen := make(map[types.Object]*variable)
	firstUseIn := make(map[types.Object]token.Pos)
	var vars []types.Object
	ast.Inspect(node, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		if start <= n.Pos() && n.End() <= end {
			var obj types.Object
			var isFree, prune bool
			switch n := n.(type) {
			case *ast.BranchStmt:
				// Avoid including labels attached to branch statements.
				return false
			case *ast.Ident:
				obj, isFree = id(n)
			case *ast.SelectorExpr:
				obj, isFree = sel(n)
				prune = true
			}
			if obj != nil {
				seen[obj] = &variable{
					obj:  obj,
					free: isFree,
				}
				vars = append(vars, obj)
				// Find the first time that the object is used in the selection.
				first, ok := firstUseIn[obj]
				if !ok || n.Pos() < first {
					firstUseIn[obj] = n.Pos()
				}
				if prune {
					return false
				}
			}
		}
		return n.Pos() <= end
	})

	// Find identifiers that are initialized or whose values are altered at some
	// point in the selected block. For example, in a selected block from lines 2-4,
	// variables x, y, and z are included in assigned. However, in a selected block
	// from lines 3-4, only variables y and z are included in assigned.
	//
	// 1: var a int
	// 2: var x int
	// 3: y := 3
	// 4: z := x + a
	//
	ast.Inspect(node, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		if n.Pos() < start || n.End() > end {
			return n.Pos() <= end
		}
		switch n := n.(type) {
		case *ast.AssignStmt:
			for _, assignment := range n.Lhs {
				lhs, ok := assignment.(*ast.Ident)
				if !ok {
					continue
				}
				obj, _ := id(lhs)
				if obj == nil {
					continue
				}
				if _, ok := seen[obj]; !ok {
					continue
				}
				seen[obj].assigned = true
				if n.Tok != token.DEFINE {
					continue
				}
				// Find identifiers that are defined prior to being used
				// elsewhere in the selection.
				// TODO: Include identifiers that are assigned prior to being
				// used elsewhere in the selection. Then, change the assignment
				// to a definition in the extracted function.
				if firstUseIn[obj] != lhs.Pos() {
					continue
				}
				// Ensure that the object is not used in its own re-definition.
				// For example:
				// var f float64
				// f, e := math.Frexp(f)
				for _, expr := range n.Rhs {
					if referencesObj(info, expr, obj) {
						continue
					}
					if _, ok := seen[obj]; !ok {
						continue
					}
					seen[obj].defined = true
					break
				}
			}
			return false
		case *ast.DeclStmt:
			gen, ok := n.Decl.(*ast.GenDecl)
			if !ok {
				return false
			}
			for _, spec := range gen.Specs {
				vSpecs, ok := spec.(*ast.ValueSpec)
				if !ok {
					continue
				}
				for _, vSpec := range vSpecs.Names {
					obj, _ := id(vSpec)
					if obj == nil {
						continue
					}
					if _, ok := seen[obj]; !ok {
						continue
					}
					seen[obj].assigned = true
				}
			}
			return false
		case *ast.IncDecStmt:
			if ident, ok := n.X.(*ast.Ident); !ok {
				return false
			} else if obj, _ := id(ident); obj == nil {
				return false
			} else {
				if _, ok := seen[obj]; !ok {
					return false
				}
				seen[obj].assigned = true
			}
		}
		return true
	})
	var variables []*variable
	for _, obj := range vars {
		v, ok := seen[obj]
		if !ok {
			return nil, fmt.Errorf("no seen types.Object for %v", obj)
		}
		if named, ok := v.obj.Type().(typesinternal.NamedOrAlias); ok {
			namedPos := named.Obj().Pos()
			if isLocal(named.Obj()) && !(start <= namedPos && namedPos <= end) {
				return nil, fmt.Errorf("Cannot extract selection: the code refers to a local type whose definition lies outside the extracted block")
			}
		}
		variables = append(variables, v)
	}
	return variables, nil
}

// referencesObj checks whether the given object appears in the given expression.
func referencesObj(info *types.Info, expr ast.Expr, obj types.Object) bool {
	var hasObj bool
	ast.Inspect(expr, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		ident, ok := n.(*ast.Ident)
		if !ok {
			return true
		}
		objUse := info.Uses[ident]
		if obj == objUse {
			hasObj = true
			return false
		}
		return false
	})
	return hasObj
}

type fnExtractParams struct {
	curStart, curEnd inspector.Cursor // first and last nodes wholly enclosed by selection
	curEnclosing     inspector.Cursor // node that encloses selection (e.g. a BlockStmt)
	curFuncDecl      inspector.Cursor // enclosing *ast.FuncDecl
}

// canExtractFunction reports whether the code in the given range can be
// extracted to a function.
func canExtractFunction(curFile inspector.Cursor, start, end token.Pos) (*fnExtractParams, bool, bool, error) {
	if start == end {
		return nil, false, false, fmt.Errorf("start and end are equal")
	}

	curEnclosing, curStart, curEnd, err := astutil.Select(curFile, start, end)
	if err != nil {
		return nil, false, false, err
	}

	// Node that encloses the selection must be a statement.
	// TODO: Support function extraction for an expression.
	if !is[ast.Stmt](curEnclosing.Node()) {
		return nil, false, false, fmt.Errorf("node is not a statement")
	}

	// Find the function declaration that encloses the selection.
	funcDecl, curFuncDecl := cursorutil.FirstEnclosing[*ast.FuncDecl](curEnclosing)
	if funcDecl == nil {
		return nil, false, false, fmt.Errorf("no enclosing function")
	}

	// If the selection is a block statement, use its first and last statements.
	// «{ ... }»  =>  { «...» }
	if is[*ast.BlockStmt](curStart.Node()) && curStart == curEnd {
		var (
			first, ok1 = curStart.FirstChild()
			last, ok2  = curStart.LastChild()
		)
		if !(ok1 && ok2) {
			return nil, false, false, fmt.Errorf("range maps to empty block statement")
		}
		curStart = first
		curEnd = last
	}

	return &fnExtractParams{
		curStart:     curStart,
		curEnd:       curEnd,
		curEnclosing: curEnclosing,
		curFuncDecl:  curFuncDecl,
	}, true, funcDecl.Recv != nil, nil
}

// objUsed checks if the object is used within the range. It returns the first
// occurrence of the object in the range, if it exists.
func objUsed(info *types.Info, start, end token.Pos, obj types.Object) (bool, *ast.Ident) {
	var firstUse *ast.Ident
	for id, objUse := range info.Uses {
		if obj != objUse {
			continue
		}
		if id.Pos() < start || id.End() > end {
			continue
		}
		if firstUse == nil || id.Pos() < firstUse.Pos() {
			firstUse = id
		}
	}
	return firstUse != nil, firstUse
}

// varOverridden traverses the given AST node until we find the given identifier. Then, we
// examine the occurrence of the given identifier and check for (1) whether the identifier
// is being redefined. If the identifier is free, we also check for (2) whether the identifier
// is being reassigned. We will not include an identifier in the return statement of the
// extracted function if it meets one of the above conditions.
func varOverridden(info *types.Info, firstUse *ast.Ident, obj types.Object, isFree bool, node ast.Node) bool {
	var isOverriden bool
	ast.Inspect(node, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		assignment, ok := n.(*ast.AssignStmt)
		if !ok {
			return true
		}
		// A free variable is initialized prior to the selection. We can always reassign
		// this variable after the selection because it has already been defined.
		// Conversely, a non-free variable is initialized within the selection. Thus, we
		// cannot reassign this variable after the selection unless it is initialized and
		// returned by the extracted function.
		if !isFree && assignment.Tok == token.ASSIGN {
			return false
		}
		for _, assigned := range assignment.Lhs {
			ident, ok := assigned.(*ast.Ident)
			// Check if we found the first use of the identifier.
			if !ok || ident != firstUse {
				continue
			}
			objUse := info.Uses[ident]
			if objUse == nil || objUse != obj {
				continue
			}
			// Ensure that the object is not used in its own definition.
			// For example:
			// var f float64
			// f, e := math.Frexp(f)
			for _, expr := range assignment.Rhs {
				if referencesObj(info, expr, obj) {
					return false
				}
			}
			isOverriden = true
			return false
		}
		return false
	})
	return isOverriden
}

// parseStmts parses the specified source (a list of statements) and
// returns them as a BlockStmt along with any associated comments.
func parseStmts(fset *token.FileSet, src []byte) (*ast.BlockStmt, []*ast.CommentGroup, error) {
	text := "package main\nfunc _() { " + string(src) + " }"
	file, err := parser.ParseFile(fset, "", text, parser.ParseComments|parser.SkipObjectResolution)
	if err != nil {
		return nil, nil, err
	}
	if len(file.Decls) != 1 {
		return nil, nil, fmt.Errorf("got %d declarations, want 1", len(file.Decls))
	}
	decl, ok := file.Decls[0].(*ast.FuncDecl)
	if !ok {
		return nil, nil, bug.Errorf("parsed file does not contain expected function declaration")
	}
	if decl.Body == nil {
		return nil, nil, bug.Errorf("extracted function has no body")
	}
	return decl.Body, file.Comments, nil
}

// generateReturnInfo generates the information we need to adjust the return statements and
// signature of the extracted function. We prepare names, signatures, and "zero values" that
// represent the new variables. We also use this information to construct the if statement that
// is inserted below the call to the extracted function.
func generateReturnInfo(enclosing *ast.FuncType, pkg *types.Package, at token.Pos, file *ast.File, info *types.Info, start, end token.Pos, hasNonNestedReturns bool, isErrHandlingReturnsCase bool) ([]*returnVariable, *ast.IfStmt, error) {
	var retVars []*returnVariable
	var cond *ast.Ident
	// Generate information for the values in the return signature of the enclosing function.
	if enclosing.Results != nil {
		nameIdx := make(map[string]int) // last integral suffixes of generated names
		qual := typesinternal.FileQualifier(file, pkg)
		for _, field := range enclosing.Results.List {
			typ := info.TypeOf(field.Type)
			if typ == nil {
				return nil, nil, fmt.Errorf(
					"failed type conversion, AST expression: %T", field.Type)
			}
			names := []string{""}
			if len(field.Names) > 0 {
				names = nil
				for _, n := range field.Names {
					names = append(names, n.Name)
				}
			}
			for _, name := range names {
				bestName := "result"
				if name != "" && name != "_" {
					bestName = name
				} else if n, ok := varNameForType(typ); ok {
					bestName = n
				}
				retName, idx := freshNameOutsideRange(info, file, at, start, end, bestName, nameIdx[bestName])
				nameIdx[bestName] = idx
				z, isValid := typesinternal.ZeroExpr(typ, qual)
				if !isValid {
					return nil, nil, fmt.Errorf("can't generate zero value for %T", typ)
				}
				retVars = append(retVars, &returnVariable{
					name:    ast.NewIdent(retName),
					decl:    &ast.Field{Type: typesinternal.TypeExpr(typ, qual)},
					zeroVal: z,
				})
			}
		}
	}
	var ifReturn *ast.IfStmt
	if !hasNonNestedReturns {
		results := getNames(retVars)
		if !isErrHandlingReturnsCase {
			// Generate information for the added bool value.
			name, _ := freshNameOutsideRange(info, file, at, start, end, "shouldReturn", 0)
			cond = &ast.Ident{Name: name}
			retVars = append(retVars, &returnVariable{
				name:    cond,
				decl:    &ast.Field{Type: ast.NewIdent("bool")},
				zeroVal: ast.NewIdent("false"),
			})
		}
		ifReturn = &ast.IfStmt{
			Cond: cond,
			Body: &ast.BlockStmt{
				List: []ast.Stmt{&ast.ReturnStmt{Results: results}},
			},
		}
	}
	return retVars, ifReturn, nil
}

type objKey struct{ pkg, name string }

// conventionalVarNames specifies conventional names for variables with various
// standard library types.
//
// Keep this up to date with completion.conventionalAcronyms.
//
// TODO(rfindley): consider factoring out a "conventions" library.
var conventionalVarNames = map[objKey]string{
	{"", "error"}:              "err",
	{"context", "Context"}:     "ctx",
	{"sql", "Tx"}:              "tx",
	{"http", "ResponseWriter"}: "rw", // Note: same as [AbbreviateVarName].
}

// varNameForType chooses a "good" name for a variable with the given type,
// if possible. Otherwise, it returns "", false.
//
// For special types, it uses known conventional names.
func varNameForType(t types.Type) (string, bool) {
	tname := typesinternal.TypeNameFor(t)
	if tname == nil {
		return "", false
	}

	// Have Alias, Basic, Named, or TypeParam.
	k := objKey{name: tname.Name()}
	if tname.Pkg() != nil {
		k.pkg = tname.Pkg().Name()
	}
	if name, ok := conventionalVarNames[k]; ok {
		return name, true
	}

	return AbbreviateVarName(tname.Name()), true
}

// adjustReturnStatements adds "zero values" of the given types to each return
// statement in the given AST node.
func adjustReturnStatements(returnTypes []*ast.Field, seenVars map[types.Object]ast.Expr, extractedBlock *ast.BlockStmt, qual types.Qualifier, isErrHandlingReturnsCase bool) error {
	var zeroVals []ast.Expr
	// Create "zero values" for each type.
	for _, returnType := range returnTypes {
		var val ast.Expr
		var isValid bool
		for obj, typ := range seenVars {
			if typ == returnType.Type {
				val, isValid = typesinternal.ZeroExpr(obj.Type(), qual)
				break
			}
		}
		if !isValid {
			return fmt.Errorf("could not find matching AST expression for %T", returnType.Type)
		}
		zeroVals = append(zeroVals, val)
	}
	// Add "zero values" to each return statement.
	// The bool reports whether the enclosing function should return after calling the
	// extracted function. We set the bool to 'true' because, if these return statements
	// execute, the extracted function terminates early, and the enclosing function must
	// return as well.
	var shouldReturnCond []ast.Expr
	if !isErrHandlingReturnsCase {
		shouldReturnCond = append(shouldReturnCond, ast.NewIdent("true"))
	}

	ast.Inspect(extractedBlock, func(n ast.Node) bool {
		if n == nil {
			return false
		}
		// Don't modify return statements inside anonymous functions.
		if _, ok := n.(*ast.FuncLit); ok {
			return false
		}
		if n, ok := n.(*ast.ReturnStmt); ok {
			n.Results = slices.Concat(zeroVals, n.Results, shouldReturnCond)
			return false
		}
		return true
	})
	return nil
}

// generateFuncCall constructs a call expression for the extracted function, described by the
// given parameters and return variables.
func generateFuncCall(hasNonNestedReturn, hasReturnVals bool, params, returns []ast.Expr, name string, token token.Token, selector string) ast.Node {
	var replace ast.Node
	callExpr := &ast.CallExpr{
		Fun:  ast.NewIdent(name),
		Args: params,
	}
	if selector != "" {
		callExpr = &ast.CallExpr{
			Fun: &ast.SelectorExpr{
				X:   ast.NewIdent(selector),
				Sel: ast.NewIdent(name),
			},
			Args: params,
		}
	}
	if hasReturnVals {
		if hasNonNestedReturn {
			// Create a return statement that returns the result of the function call.
			replace = &ast.ReturnStmt{
				Return:  0,
				Results: []ast.Expr{callExpr},
			}
		} else {
			// Assign the result of the function call.
			replace = &ast.AssignStmt{
				Lhs: returns,
				Tok: token,
				Rhs: []ast.Expr{callExpr},
			}
		}
	} else {
		replace = callExpr
	}
	return replace
}

// initializeVars creates variable declarations, if needed.
// Our preference is to replace the selected block with an "x, y, z := fn()" style
// assignment statement. We can use this style when all of the variables in the
// extracted function's return statement are either not defined prior to the extracted block
// or can be safely redefined. However, for example, if z is already defined
// in a different scope, we replace the selected block with:
//
// var x int
// var y string
// x, y, z = fn()
func initializeVars(uninitialized []types.Object, retVars []*returnVariable, seenUninitialized map[types.Object]struct{}, seenVars map[types.Object]ast.Expr) []ast.Stmt {
	var declarations []ast.Stmt
	for _, obj := range uninitialized {
		if _, ok := seenUninitialized[obj]; ok {
			continue
		}
		seenUninitialized[obj] = struct{}{}
		valSpec := &ast.ValueSpec{
			Names: []*ast.Ident{ast.NewIdent(obj.Name())},
			Type:  seenVars[obj],
		}
		genDecl := &ast.GenDecl{
			Tok:   token.VAR,
			Specs: []ast.Spec{valSpec},
		}
		declarations = append(declarations, &ast.DeclStmt{Decl: genDecl})
	}
	// Each variable added from a return statement in the selection
	// must be initialized.
	for i, retVar := range retVars {
		valSpec := &ast.ValueSpec{
			Names: []*ast.Ident{retVar.name},
			Type:  retVars[i].decl.Type,
		}
		genDecl := &ast.GenDecl{
			Tok:   token.VAR,
			Specs: []ast.Spec{valSpec},
		}
		declarations = append(declarations, &ast.DeclStmt{Decl: genDecl})
	}
	return declarations
}

// getNames returns the names from the given list of returnVariable.
func getNames(retVars []*returnVariable) []ast.Expr {
	var names []ast.Expr
	for _, retVar := range retVars {
		names = append(names, retVar.name)
	}
	return names
}

// getZeroVals returns the "zero values" from the given list of returnVariable.
func getZeroVals(retVars []*returnVariable) []ast.Expr {
	var zvs []ast.Expr
	for _, retVar := range retVars {
		zvs = append(zvs, retVar.zeroVal)
	}
	return zvs
}

// getDecls returns the declarations from the given list of returnVariable.
func getDecls(retVars []*returnVariable) []*ast.Field {
	var decls []*ast.Field
	for _, retVar := range retVars {
		decls = append(decls, retVar.decl)
	}
	return decls
}

func cond[T any](cond bool, t, f T) T {
	if cond {
		return t
	} else {
		return f
	}
}

// replaceBranchStmtWithReturnStmt modifies the ast node to replace the given
// branch statement with the given return statement.
func replaceBranchStmtWithReturnStmt(block ast.Node, br *ast.BranchStmt, ret *ast.ReturnStmt) {
	ast.Inspect(block, func(n ast.Node) bool {
		// Look for the branch statement within a BlockStmt or CaseClause.
		switch n := n.(type) {
		case *ast.BlockStmt:
			for i, stmt := range n.List {
				if stmt == br {
					n.List[i] = ret
					return false
				}
			}
		case *ast.CaseClause:
			for i, stmt := range n.Body {
				if stmt.Pos() == br.Pos() {
					n.Body[i] = ret
					return false
				}
			}
		}
		return true
	})
}

// freeBranches returns all branch statements beneath cur whose continuation
// lies outside the (start, end) range.
func freeBranches(info *types.Info, cur inspector.Cursor, start, end token.Pos) (free []*ast.BranchStmt) {
nextBranch:
	for curBr := range cur.Preorder((*ast.BranchStmt)(nil)) {
		br := curBr.Node().(*ast.BranchStmt)
		if br.End() < start || br.Pos() > end {
			continue
		}
		label, _ := info.Uses[br.Label].(*types.Label)
		if label != nil && !(start <= label.Pos() && label.Pos() <= end) {
			free = append(free, br)
			continue
		}
		if br.Tok == token.BREAK || br.Tok == token.CONTINUE {
			filter := []ast.Node{
				(*ast.ForStmt)(nil),
				(*ast.RangeStmt)(nil),
				(*ast.SwitchStmt)(nil),
				(*ast.TypeSwitchStmt)(nil),
				(*ast.SelectStmt)(nil),
			}
			// Find innermost relevant ancestor for break/continue.
			for curAncestor := range curBr.Parent().Enclosing(filter...) {
				if l, ok := curAncestor.Parent().Node().(*ast.LabeledStmt); ok &&
					label != nil &&
					l.Label.Name == label.Name() {
					continue
				}
				switch n := curAncestor.Node().(type) {
				case *ast.ForStmt, *ast.RangeStmt:
					if n.Pos() < start {
						free = append(free, br)
					}
					continue nextBranch
				case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
					if br.Tok == token.BREAK {
						if n.Pos() < start {
							free = append(free, br)
						}
						continue nextBranch
					}
				}
			}
		}
	}
	return
}

// isFreeBranchStmt returns true if the relevant ancestor for the branch
// statement at stack[len(stack)-1] cannot be found in the stack (for
// break/continue) or the extracted block (for goto). This is used when we are
// examining the extracted block, since type information isn't available. We
// need to find the location of the label without using types.Info.
// We treat goto and break/continue separately because while break/continue
// must be used within a for, range, switch, or select, goto's use is
// less restrictive within a function body.
func isFreeBranchStmt(stack []ast.Node, extractedBlock *ast.BlockStmt) bool {
	switch node := stack[len(stack)-1].(type) {
	case *ast.BranchStmt:
		isLabeled := node.Label != nil
		switch node.Tok {
		case token.GOTO:
			if isLabeled {
				for _, stmt := range extractedBlock.List {
					if l, ok := stmt.(*ast.LabeledStmt); ok && l.Label != nil && l.Label.Name == node.Label.Name {
						// We found the label in the extracted block, so it's not a free branch stmt.
						return false
					}
				}
				return true
			}
		case token.BREAK, token.CONTINUE:
			// Find innermost relevant ancestor for break/continue.
			for i := len(stack) - 2; i >= 0; i-- {
				n := stack[i]
				if isLabeled {
					l, ok := n.(*ast.LabeledStmt)
					if !(ok && l.Label.Name == node.Label.Name) {
						continue
					}
				}
				switch n.(type) {
				case *ast.ForStmt, *ast.RangeStmt, *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
					return false
				}
			}
		}
	}
	// We didn't find the relevant ancestor on the path, so this must be a free branch statement.
	return true
}


================================================
FILE: gopls/internal/golang/extracttofile.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines the code action "Extract declarations to new file".

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// canExtractToNewFile reports whether the code in the given range can be extracted to a new file.
func canExtractToNewFile(pgf *parsego.File, start, end token.Pos) bool {
	_, _, _, ok := selectedToplevelDecls(pgf, start, end)
	return ok
}

// findImportEdits finds imports specs that needs to be added to the new file
// or deleted from the old file if the range is extracted to a new file.
//
// TODO: handle dot imports.
func findImportEdits(file *ast.File, info *types.Info, start, end token.Pos) (adds, deletes []*ast.ImportSpec, _ error) {
	// make a map from a pkgName to its references
	pkgNameReferences := make(map[*types.PkgName][]*ast.Ident)
	for ident, use := range info.Uses {
		if pkgName, ok := use.(*types.PkgName); ok {
			pkgNameReferences[pkgName] = append(pkgNameReferences[pkgName], ident)
		}
	}

	// PkgName referenced in the extracted selection must be
	// imported in the new file.
	// PkgName only referenced in the extracted selection must be
	// deleted from the original file.
	for _, spec := range file.Imports {
		if spec.Name != nil && spec.Name.Name == "." {
			// TODO: support dot imports.
			return nil, nil, errors.New("\"extract to new file\" does not support files containing dot imports")
		}
		pkgName := info.PkgNameOf(spec)
		if pkgName == nil {
			continue
		}
		usedInSelection := false
		usedInNonSelection := false
		for _, ident := range pkgNameReferences[pkgName] {
			if posRangeContains(start, end, ident.Pos(), ident.End()) {
				usedInSelection = true
			} else {
				usedInNonSelection = true
			}
		}
		if usedInSelection {
			adds = append(adds, spec)
		}
		if usedInSelection && !usedInNonSelection {
			deletes = append(deletes, spec)
		}
	}

	return adds, deletes, nil
}

// ExtractToNewFile moves selected declarations into a new file.
func ExtractToNewFile(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.DocumentChange, error) {
	errorPrefix := "ExtractToNewFile"

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}

	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", errorPrefix, err)
	}

	// Expand the selection, and compute the portion to extract.
	start, end, firstSymbol, ok := selectedToplevelDecls(pgf, start, end)
	if !ok {
		return nil, fmt.Errorf("invalid selection")
	}
	pgf.CheckPos(start) // #70553
	// Inv: start is valid wrt pgf.Tok.

	// select trailing empty lines
	offset, err := safetoken.Offset(pgf.Tok, end)
	if err != nil {
		return nil, err
	}
	rest := pgf.Src[offset:]
	spaces := len(rest) - len(bytes.TrimLeft(rest, " \t\n"))
	end += token.Pos(spaces)
	pgf.CheckPos(end) // #70553
	if !(start <= end) {
		bug.Reportf("start: not before end")
	}
	// Inv: end is valid wrt pgf.Tok; env >= start.
	fileStart := pgf.File.FileStart
	pgf.CheckPos(fileStart) // #70553
	if !(0 <= start-fileStart) {
		bug.Reportf("start: out of bounds")
	}
	if !(int(end-fileStart) <= len(pgf.Src)) {
		bug.Reportf("end: out of bounds")
	}
	// Inv: 0 <= start-fileStart <= end-fileStart <= len(Src).
	src := pgf.Src[start-fileStart : end-fileStart]

	replaceRange, err := pgf.PosRange(start, end)
	if err != nil {
		return nil, bug.Errorf("invalid range: %v", err)
	}

	adds, deletes, err := findImportEdits(pgf.File, pkg.TypesInfo(), start, end)
	if err != nil {
		return nil, err
	}

	var importDeletes []protocol.TextEdit
	// For unparenthesised declarations like `import "fmt"` we remove
	// the whole declaration because simply removing importSpec leaves
	// `import \n`, which does not compile.
	// For parenthesised declarations like `import ("fmt"\n "log")`
	// we only remove the ImportSpec, because removing the whole declaration
	// might remove other ImportsSpecs we don't want to touch.
	unparenthesizedImports := unparenthesizedImports(pgf)
	for _, importSpec := range deletes {
		if decl := unparenthesizedImports[importSpec]; decl != nil {
			importDeletes = append(importDeletes, removeNode(pgf, decl))
		} else {
			importDeletes = append(importDeletes, removeNode(pgf, importSpec))
		}
	}

	var buf bytes.Buffer
	if c := CopyrightComment(pgf.File); c != nil {
		text, err := pgf.NodeText(c)
		if err != nil {
			return nil, err
		}
		buf.Write(text)
		// One empty line between copyright header and following.
		buf.WriteString("\n\n")
	}

	if c := buildConstraintComment(pgf.File); c != nil {
		text, err := pgf.NodeText(c)
		if err != nil {
			return nil, err
		}
		buf.Write(text)
		// One empty line between build constraint and following.
		buf.WriteString("\n\n")
	}

	fmt.Fprintf(&buf, "package %s\n", pgf.File.Name.Name)
	if len(adds) > 0 {
		buf.WriteString("import (")
		for _, importSpec := range adds {
			if importSpec.Name != nil {
				fmt.Fprintf(&buf, "%s %s\n", importSpec.Name.Name, importSpec.Path.Value)
			} else {
				fmt.Fprintf(&buf, "%s\n", importSpec.Path.Value)
			}
		}
		buf.WriteString(")\n")
	}

	newFile, err := chooseNewFile(ctx, snapshot, pgf.URI.DirPath(), firstSymbol)
	if err != nil {
		return nil, fmt.Errorf("%s: %w", errorPrefix, err)
	}

	buf.Write(src)

	newFileContent, err := format.Source(buf.Bytes())
	if err != nil {
		return nil, err
	}

	return []protocol.DocumentChange{
		// edit the original file
		protocol.DocumentChangeEdit(fh, append(importDeletes, protocol.TextEdit{Range: replaceRange, NewText: ""})),
		// create a new file
		protocol.DocumentChangeCreate(newFile.URI()),
		// edit the created file
		protocol.DocumentChangeEdit(newFile, []protocol.TextEdit{
			{Range: protocol.Range{}, NewText: string(newFileContent)},
		})}, nil
}

// chooseNewFile chooses a new filename in dir, based on the name of the
// first extracted symbol, and if necessary to disambiguate, a numeric suffix.
func chooseNewFile(ctx context.Context, snapshot *cache.Snapshot, dir string, firstSymbol string) (file.Handle, error) {
	basename := strings.ToLower(firstSymbol)
	newPath := protocol.URIFromPath(filepath.Join(dir, basename+".go"))
	for count := 1; count < 5; count++ {
		fh, err := snapshot.ReadFile(ctx, newPath)
		if err != nil {
			return nil, err // canceled
		}
		if _, err := fh.Content(); errors.Is(err, os.ErrNotExist) {
			return fh, nil
		}
		filename := fmt.Sprintf("%s.%d.go", basename, count)
		newPath = protocol.URIFromPath(filepath.Join(dir, filename))
	}
	return nil, fmt.Errorf("chooseNewFileURI: exceeded retry limit")
}

// selectedToplevelDecls returns the lexical extent of the top-level
// declarations enclosed by [start, end), along with the name of the
// first declaration. The returned boolean reports whether the selection
// should be offered a code action to extract the declarations.
func selectedToplevelDecls(pgf *parsego.File, start, end token.Pos) (token.Pos, token.Pos, string, bool) {
	// selection cannot intersect a package declaration
	if posRangeIntersects(start, end, pgf.File.Package, pgf.File.Name.End()) {
		return 0, 0, "", false
	}
	firstName := ""
	for _, decl := range pgf.File.Decls {
		if posRangeIntersects(start, end, decl.Pos(), decl.End()) {
			var (
				comment *ast.CommentGroup // (include comment preceding decl)
				id      *ast.Ident
			)
			switch decl := decl.(type) {
			case *ast.BadDecl:
				return 0, 0, "", false

			case *ast.FuncDecl:
				// if only selecting keyword "func" or function name, extend selection to the
				// whole function
				if posRangeContains(decl.Pos(), decl.Name.End(), start, end) {
					pgf.CheckNode(decl) // #70553
					start, end = decl.Pos(), decl.End()
					// Inv: start, end are valid wrt pgf.Tok.
				}
				comment = decl.Doc
				id = decl.Name

			case *ast.GenDecl:
				// selection cannot intersect an import declaration
				if decl.Tok == token.IMPORT {
					return 0, 0, "", false
				}
				// if only selecting keyword "type", "const", or "var", extend selection to the
				// whole declaration
				if decl.Tok == token.TYPE && posRangeContains(decl.Pos(), decl.Pos()+token.Pos(len("type")), start, end) ||
					decl.Tok == token.CONST && posRangeContains(decl.Pos(), decl.Pos()+token.Pos(len("const")), start, end) ||
					decl.Tok == token.VAR && posRangeContains(decl.Pos(), decl.Pos()+token.Pos(len("var")), start, end) {
					pgf.CheckNode(decl) // #70553
					start, end = decl.Pos(), decl.End()
					// Inv: start, end are valid wrt pgf.Tok.
				}
				comment = decl.Doc
				if len(decl.Specs) > 0 {
					switch spec := decl.Specs[0].(type) {
					case *ast.TypeSpec:
						id = spec.Name
					case *ast.ValueSpec:
						id = spec.Names[0]
					}
				}
			}
			// selection cannot partially intersect a node
			if !posRangeContains(start, end, decl.Pos(), decl.End()) {
				return 0, 0, "", false
			}
			if id != nil && firstName == "" {
				// may be "_"
				firstName = id.Name
			}
			if comment != nil && comment.Pos() < start {
				pgf.CheckNode(comment) // #70553
				start = comment.Pos()
				// Inv: start is valid wrt pgf.Tok.
			}
		}
	}
	for _, comment := range pgf.File.Comments {
		if posRangeIntersects(start, end, comment.Pos(), comment.End()) {
			if !posRangeContains(start, end, comment.Pos(), comment.End()) {
				// selection cannot partially intersect a comment
				return 0, 0, "", false
			}
		}
	}
	if firstName == "" {
		return 0, 0, "", false
	}
	return start, end, firstName, true
}

// unparenthesizedImports returns a map from each unparenthesized ImportSpec
// to its enclosing declaration (which may need to be deleted too).
func unparenthesizedImports(pgf *parsego.File) map[*ast.ImportSpec]*ast.GenDecl {
	decls := make(map[*ast.ImportSpec]*ast.GenDecl)
	for _, decl := range pgf.File.Decls {
		if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT && !decl.Lparen.IsValid() {
			decls[decl.Specs[0].(*ast.ImportSpec)] = decl
		}
	}
	return decls
}

// removeNode returns a TextEdit that removes the node.
func removeNode(pgf *parsego.File, node ast.Node) protocol.TextEdit {
	rng, err := pgf.NodeRange(node)
	if err != nil {
		bug.Reportf("removeNode: %v", err)
	}
	return protocol.TextEdit{Range: rng, NewText: ""}
}

// posRangeIntersects checks if [a, b) and [c, d) intersects, assuming a <= b and c <= d.
func posRangeIntersects(a, b, c, d token.Pos) bool {
	return !(b <= c || d <= a)
}

// posRangeContains checks if [a, b) contains [c, d), assuming a <= b and c <= d.
func posRangeContains(a, b, c, d token.Pos) bool {
	return a <= c && d <= b
}


================================================
FILE: gopls/internal/golang/fix.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/token"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/gopls/internal/analysis/fillstruct"
	"golang.org/x/tools/gopls/internal/analysis/unusedparams"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
)

// A fixer is a function that suggests a fix for a diagnostic produced
// by the analysis framework. This is done outside of the analyzer Run
// function so that the construction of expensive fixes can be
// deferred until they are requested by the user.
//
// The actual diagnostic is not provided; only its position, as the
// triple (pgf, start, end); the resulting SuggestedFix implicitly
// relates to that file.
//
// The supplied token positions (start, end) must belong to
// pkg.FileSet(), and the returned positions
// (SuggestedFix.TextEdits[*].{Pos,End}) must belong to the returned
// FileSet, which is not necessarily the same.
// (See [insertDeclsAfter] for explanation.)
//
// A fixer may return (nil, nil) if no fix is available.
type fixer func(ctx context.Context, s *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error)

// A singleFileFixer is a [fixer] that inspects only a single file.
type singleFileFixer func(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error)

// singleFile adapts a [singleFileFixer] to a [fixer]
// by discarding the snapshot and the context it needs.
func singleFile(fixer1 singleFileFixer) fixer {
	return func(_ context.Context, _ *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
		return fixer1(pkg, pgf, start, end)
	}
}

// Names of ApplyFix.Fix created directly by the CodeAction handler.
const (
	fixExtractVariable         = "extract_variable" // (or constant)
	fixExtractVariableAll      = "extract_variable_all"
	fixExtractFunction         = "extract_function"
	fixExtractMethod           = "extract_method"
	fixInlineCall              = "inline_call" // keep consistent with go/analysis/passes/inline Diagnostic.Category
	fixInlineVariable          = "inline_variable"
	fixInvertIfCondition       = "invert_if_condition"
	fixSplitLines              = "split_lines"
	fixJoinLines               = "join_lines"
	fixCreateUndeclared        = "create_undeclared"
	fixMissingInterfaceMethods = "stub_missing_interface_method"
	fixMissingCalledFunction   = "stub_missing_called_function"
)

// ApplyFix applies the specified kind of suggested fix to the given
// file and range, returning the resulting changes.
//
// A fix kind is either the Category of an analysis.Diagnostic that
// had a SuggestedFix with no edits; or the name of a fix agreed upon
// by [CodeActions] and this function.
// Fix kinds identify fixes in the command protocol.
//
// TODO(adonovan): come up with a better mechanism for registering the
// connection between analyzers, code actions, and fixers. A flaw of
// the current approach is that the same Category could in theory
// apply to a Diagnostic with several lazy fixes, making them
// impossible to distinguish. It would more precise if there was a
// SuggestedFix.Category field, or some other way to squirrel metadata
// in the fix.
func ApplyFix(ctx context.Context, fix string, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.DocumentChange, error) {
	// This can't be expressed as an entry in the fixer table below
	// because it operates in the protocol (not go/{token,ast}) domain.
	// (Sigh; perhaps it was a mistake to factor out the
	// NarrowestPackageForFile/RangePos/suggestedFixToEdits
	// steps.)
	if fix == unusedparams.FixCategory {
		return removeParam(ctx, snapshot, fh, rng)
	}

	fixers := map[string]fixer{
		// Fixes for analyzer-provided diagnostics.
		// These match the Diagnostic.Category.
		fillstruct.FixCategory: singleFile(fillstruct.SuggestedFix),

		// Ad-hoc fixers: these are used when the command is
		// constructed directly by logic in server/code_action.
		fixExtractFunction:         singleFile(extractFunction),
		fixExtractMethod:           singleFile(extractMethod),
		fixExtractVariable:         singleFile(extractVariableOne),
		fixExtractVariableAll:      singleFile(extractVariableAll),
		fixInlineCall:              inlineCall,
		fixInlineVariable:          singleFile(inlineVariableOne),
		fixInvertIfCondition:       singleFile(invertIfCondition),
		fixSplitLines:              singleFile(splitLines),
		fixJoinLines:               singleFile(joinLines),
		fixCreateUndeclared:        singleFile(createUndeclared),
		fixMissingInterfaceMethods: stubMissingInterfaceMethodsFixer,
		fixMissingCalledFunction:   stubMissingCalledFunctionFixer,
	}
	fixer, ok := fixers[fix]
	if !ok {
		return nil, fmt.Errorf("no suggested fix function for %s", fix)
	}
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	fixFset, suggestion, err := fixer(ctx, snapshot, pkg, pgf, start, end)
	if err != nil {
		return nil, err
	}
	if suggestion == nil {
		return nil, nil
	}
	return suggestedFixToDocumentChange(ctx, snapshot, fixFset, suggestion)
}

// suggestedFixToDocumentChange converts the suggestion's edits from analysis form into protocol form.
func suggestedFixToDocumentChange(ctx context.Context, snapshot *cache.Snapshot, fset *token.FileSet, suggestion *analysis.SuggestedFix) ([]protocol.DocumentChange, error) {
	type fileInfo struct {
		fh     file.Handle
		mapper *protocol.Mapper
		edits  []protocol.TextEdit
	}
	files := make(map[protocol.DocumentURI]*fileInfo)
	for _, edit := range suggestion.TextEdits {
		tokFile := fset.File(edit.Pos)
		if tokFile == nil {
			return nil, bug.Errorf("no file for edit position")
		}
		end := edit.End
		if !end.IsValid() {
			end = edit.Pos
		}
		uri := protocol.URIFromPath(tokFile.Name())
		info, ok := files[uri]
		if !ok {
			// First edit: create a mapper.
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return nil, err
			}
			content, err := fh.Content()
			if err != nil {
				return nil, err
			}
			mapper := protocol.NewMapper(uri, content)
			info = &fileInfo{fh, mapper, nil}
			files[uri] = info
		}
		rng, err := info.mapper.PosRange(tokFile, edit.Pos, end)
		if err != nil {
			return nil, err
		}
		info.edits = append(info.edits, protocol.TextEdit{
			Range:   rng,
			NewText: string(edit.NewText),
		})
	}
	var changes []protocol.DocumentChange
	for _, info := range files {
		change := protocol.DocumentChangeEdit(info.fh, info.edits)
		changes = append(changes, change)
	}
	return changes, nil
}


================================================
FILE: gopls/internal/golang/folding_range.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"cmp"
	"context"
	"go/ast"
	"go/token"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// FoldingRange gets all of the folding range for f.
func FoldingRange(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, lineFoldingOnly bool) ([]protocol.FoldingRange, error) {
	// TODO(suzmue): consider limiting the number of folding ranges returned, and
	// implement a way to prioritize folding ranges in that case.
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}

	// With parse errors, we wouldn't be able to produce accurate folding info.
	// LSP protocol (3.16) currently does not have a way to handle this case
	// (https://github.com/microsoft/language-server-protocol/issues/1200).
	// We cannot return an error either because we are afraid some editors
	// may not handle errors nicely. As a workaround, we now return an empty
	// result and let the client handle this case by double check the file
	// contents (i.e. if the file is not empty and the folding range result
	// is empty, raise an internal error).
	if pgf.ParseErr != nil {
		return nil, nil
	}

	// Get folding ranges for comments separately as they are not walked by ast.Inspect.
	ranges := commentsFoldingRange(pgf)

	// Walk the ast and collect folding ranges.
	filter := []ast.Node{
		(*ast.BasicLit)(nil),
		(*ast.BlockStmt)(nil),
		(*ast.CallExpr)(nil),
		(*ast.CaseClause)(nil),
		(*ast.CommClause)(nil),
		(*ast.CompositeLit)(nil),
		(*ast.FieldList)(nil),
		(*ast.GenDecl)(nil),
	}
	for cur := range pgf.Cursor().Preorder(filter...) {
		var kind protocol.FoldingRangeKind
		// start and end define the range of content to fold away.
		var start, end token.Pos
		switch n := cur.Node().(type) {
		case *ast.BlockStmt:
			// Fold between positions of or lines between "{" and "}".
			start, end = bracketedFoldingRange(pgf, n.Lbrace, n.Rbrace, lineFoldingOnly)

		case *ast.CaseClause:
			// Fold from position of ":" to end.
			start, end = n.Colon+1, n.End()

		case *ast.CommClause:
			// Fold from position of ":" to end.
			start, end = n.Colon+1, n.End()

		case *ast.CallExpr:
			// Fold between positions of or lines between "(" and ")".
			start, end = bracketedFoldingRange(pgf, n.Lparen, n.Rparen, lineFoldingOnly)

		case *ast.FieldList:
			// Fold between positions of or lines between opening parenthesis/brace and closing parenthesis/brace.
			start, end = bracketedFoldingRange(pgf, n.Opening, n.Closing, lineFoldingOnly)

		case *ast.GenDecl:
			// If this is an import declaration, set the kind to be protocol.Imports.
			if n.Tok == token.IMPORT {
				kind = protocol.Imports
			}
			// Fold between positions of or lines between "(" and ")".
			start, end = bracketedFoldingRange(pgf, n.Lparen, n.Rparen, lineFoldingOnly)

		case *ast.BasicLit:
			// Fold raw string literals from position of "`" to position of "`".
			if n.Kind == token.STRING && len(n.Value) >= 2 && n.Value[0] == '`' && n.Value[len(n.Value)-1] == '`' {
				start, end = n.Pos(), n.End()
			}

		case *ast.CompositeLit:
			// Fold between positions of or lines between "{" and "}".
			start, end = bracketedFoldingRange(pgf, n.Lbrace, n.Rbrace, lineFoldingOnly)

		default:
			panic(n)
		}

		// Check that folding positions are valid.
		if !start.IsValid() || !end.IsValid() {
			continue
		}
		if start == end {
			// Nothing to fold.
			continue
		}
		// in line folding mode, do not fold if the start and end lines are the same.
		if lineFoldingOnly && safetoken.Line(pgf.Tok, start) == safetoken.Line(pgf.Tok, end) {
			continue
		}
		rng, err := pgf.PosRange(start, end)
		if err != nil {
			bug.Reportf("failed to create range: %s", err) // can't happen
			continue
		}
		ranges = append(ranges, foldingRange(kind, rng))
	}

	// Sort by start position.
	slices.SortFunc(ranges, func(x, y protocol.FoldingRange) int {
		if d := cmp.Compare(*x.StartLine, *y.StartLine); d != 0 {
			return d
		}
		return cmp.Compare(*x.StartCharacter, *y.StartCharacter)
	})

	return ranges, nil
}

// bracketedFoldingRange returns the folding range for nodes with parentheses/braces/brackets
// that potentially can take up multiple lines.
func bracketedFoldingRange(pgf *parsego.File, open, close token.Pos, lineFoldingOnly bool) (token.Pos, token.Pos) {
	if !open.IsValid() || !close.IsValid() {
		return token.NoPos, token.NoPos
	}
	if open+1 == close {
		// Nothing to fold: (), {} or [].
		return token.NoPos, token.NoPos
	}

	if !lineFoldingOnly {
		return open + 1, close
	}

	// Clients with "LineFoldingOnly" set to true can fold only full lines.
	// This is also checked in the caller.
	//
	// Clients that support folding ranges can display them in various ways
	// (e.g., how are folding ranges marked? is the final line displayed?).
	// The most common client
	// is vscode, which displays the first line followed by ..., and then does not
	// display any other lines in the range, but other clients might also display
	// final line of the range. For example, the following code
	//
	//	var x = []string{"a",
	//	"b",
	//	"c" }
	//
	// can be folded (in vscode) to
	//
	// var x = []string{"a", ...
	//
	// or in some other client
	//
	//	var x = []string{"a", ...
	//	"c" }
	//
	// This code displays the final line containing ),},], but not the closing quote
	// of a multi-line string

	prevLineEnd := pgf.Tok.LineStart(safetoken.Line(pgf.Tok, close)) - 1 // there was a previous line
	if prevLineEnd <= open {                                             // all the same line
		return token.NoPos, token.NoPos
	}
	return open + 1, prevLineEnd
}

// commentsFoldingRange returns the folding ranges for all comment blocks in file.
// The folding range starts at the end of the first line of the comment block, and ends at the end of the
// comment block and has kind protocol.Comment.
func commentsFoldingRange(pgf *parsego.File) (comments []protocol.FoldingRange) {
	tokFile := pgf.Tok
	for _, commentGrp := range pgf.File.Comments {
		startGrpLine, endGrpLine := safetoken.Line(tokFile, commentGrp.Pos()), safetoken.Line(tokFile, commentGrp.End())
		if startGrpLine == endGrpLine {
			// Don't fold single line comments.
			continue
		}

		firstComment := commentGrp.List[0]
		startPos, endLinePos := firstComment.Pos(), firstComment.End()
		startCmmntLine, endCmmntLine := safetoken.Line(tokFile, startPos), safetoken.Line(tokFile, endLinePos)
		if startCmmntLine != endCmmntLine {
			// If the first comment spans multiple lines, then we want to have the
			// folding range start at the end of the first line.
			endLinePos = token.Pos(int(startPos) + len(strings.Split(firstComment.Text, "\n")[0]))
		}
		rng, err := pgf.PosRange(endLinePos, commentGrp.End())
		if err != nil {
			bug.Reportf("failed to create mapped range: %s", err) // can't happen
			continue
		}
		// Fold from the end of the first line comment to the end of the comment block.
		comments = append(comments, foldingRange(protocol.Comment, rng))
	}
	return comments
}

func foldingRange(kind protocol.FoldingRangeKind, rng protocol.Range) protocol.FoldingRange {
	return protocol.FoldingRange{
		// (I guess LSP doesn't use a protocol.Range here
		// because missing means something different from zero.)
		StartLine:      varOf(rng.Start.Line),
		StartCharacter: varOf(rng.Start.Character),
		EndLine:        varOf(rng.End.Line),
		EndCharacter:   varOf(rng.End.Character),
		Kind:           string(kind),
	}
}

// varOf returns a new variable whose value is x.
func varOf[T any](x T) *T { return &x }


================================================
FILE: gopls/internal/golang/format.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package golang defines the LSP features for navigation, analysis,
// and refactoring of Go source code.
package golang

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"strings"
	"text/scanner"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
	gofumptFormat "mvdan.cc/gofumpt/format"
)

// Format formats a file with a given range.
func Format(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.TextEdit, error) {
	ctx, done := event.Start(ctx, "golang.Format")
	defer done()

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}

	// Even if this file has parse errors, it might still be possible to format it.
	// Using format.Node on an AST with errors may result in code being modified.
	// Attempt to format the source of this file instead.
	if pgf.ParseErr != nil {
		formatted, err := formatSource(ctx, fh)
		if err != nil {
			return nil, err
		}
		return computeTextEdits(ctx, pgf, string(formatted))
	}

	// format.Node changes slightly from one release to another, so the version
	// of Go used to build the LSP server will determine how it formats code.
	// This should be acceptable for all users, who likely be prompted to rebuild
	// the LSP server on each Go release.
	buf := &bytes.Buffer{}
	fset := tokeninternal.FileSetFor(pgf.Tok)
	if err := format.Node(buf, fset, pgf.File); err != nil {
		return nil, err
	}
	formatted := buf.String()

	// Apply additional formatting, if any is supported. Currently, the only
	// supported additional formatter is gofumpt.
	if snapshot.Options().Gofumpt {
		// gofumpt can customize formatting based on language version and module
		// path, if available.
		//
		// Try to derive this information, but fall-back on the default behavior.
		//
		// TODO: under which circumstances can we fail to find module information?
		// Can this, for example, result in inconsistent formatting across saves,
		// due to pending calls to packages.Load?
		var opts gofumptFormat.Options
		meta, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
		if err == nil {
			if mi := meta.Module; mi != nil {
				if v := mi.GoVersion; v != "" {
					opts.LangVersion = "go" + v
				}
				opts.ModulePath = mi.Path
			}
		}
		b, err := gofumptFormat.Source(buf.Bytes(), opts)
		if err != nil {
			return nil, err
		}
		formatted = string(b)
	}
	return computeTextEdits(ctx, pgf, formatted)
}

func formatSource(ctx context.Context, fh file.Handle) ([]byte, error) {
	_, done := event.Start(ctx, "golang.formatSource")
	defer done()

	data, err := fh.Content()
	if err != nil {
		return nil, err
	}
	return format.Source(data)
}

type importFix struct {
	fix   *imports.ImportFix
	edits []protocol.TextEdit
}

// allImportsFixes formats f for each possible fix to the imports.
// In addition to returning the result of applying all edits,
// it returns a list of fixes that could be applied to the file, with the
// corresponding TextEdits that would be needed to apply that fix.
func allImportsFixes(ctx context.Context, snapshot *cache.Snapshot, pgf *parsego.File) (allFixEdits []protocol.TextEdit, editsPerFix []*importFix, err error) {
	ctx, done := event.Start(ctx, "golang.allImportsFixes")
	defer done()

	if err := snapshot.RunProcessEnvFunc(ctx, func(ctx context.Context, opts *imports.Options) error {
		allFixEdits, editsPerFix, err = computeImportEdits(ctx, pgf, snapshot, opts)
		return err
	}); err != nil {
		return nil, nil, fmt.Errorf("allImportsFixes: %v", err)
	}
	return allFixEdits, editsPerFix, nil
}

// computeImportEdits computes a set of edits that perform one or all of the
// necessary import fixes.
func computeImportEdits(ctx context.Context, pgf *parsego.File, snapshot *cache.Snapshot, options *imports.Options) (allFixEdits []protocol.TextEdit, editsPerFix []*importFix, err error) {
	goroot := snapshot.View().Folder().Env.GOROOT
	filename := pgf.URI.Path()

	// Build up basic information about the original file.
	isource, err := imports.NewProcessEnvSource(options.Env, filename, pgf.File.Name.Name)
	if err != nil {
		return nil, nil, err
	}
	var source imports.Source

	// Keep this in sync with [cache.Session.createView] (see the TODO there: we
	// should factor out the handling of the ImportsSource setting).
	switch snapshot.Options().ImportsSource {
	case settings.ImportsSourceGopls:
		source = snapshot.NewGoplsSource(isource)
	case settings.ImportsSourceOff: // for cider, which has no file system
		source = nil
	case settings.ImportsSourceGoimports:
		source = isource
	}
	// imports require a current metadata graph
	// TODO(rfindley): improve the API
	snapshot.WorkspaceMetadata(ctx) // ignore error
	allFixes, err := imports.FixImports(ctx, filename, pgf.Src, goroot, options.Env.Logf, source)
	if err != nil {
		return nil, nil, err
	}

	allFixEdits, err = computeFixEdits(pgf.Src, options, allFixes)
	if err != nil {
		return nil, nil, err
	}

	// Apply all of the import fixes to the file.
	// Add the edits for each fix to the result.
	for _, fix := range allFixes {
		edits, err := computeFixEdits(pgf.Src, options, []*imports.ImportFix{fix})
		if err != nil {
			return nil, nil, err
		}
		editsPerFix = append(editsPerFix, &importFix{
			fix:   fix,
			edits: edits,
		})
	}
	return allFixEdits, editsPerFix, nil
}

// ComputeImportFixEdits returns text edits for a single import fix.
func ComputeImportFixEdits(localPrefix string, src []byte, fixes ...*imports.ImportFix) ([]protocol.TextEdit, error) {
	options := &imports.Options{
		LocalPrefix: localPrefix,
		// Defaults.
		AllErrors:  true,
		Comments:   true,
		Fragment:   true,
		FormatOnly: false,
		TabIndent:  true,
		TabWidth:   8,
	}
	return computeFixEdits(src, options, fixes)
}

func computeFixEdits(src []byte, options *imports.Options, fixes []*imports.ImportFix) ([]protocol.TextEdit, error) {
	// trim the original data to match fixedData
	left, err := importPrefix(src)
	if err != nil {
		return nil, err
	}
	extra := !strings.Contains(left, "\n") // one line may have more than imports
	if extra {
		left = string(src)
	}
	if len(left) > 0 && left[len(left)-1] != '\n' {
		left += "\n"
	}
	// Apply the fixes and re-parse the file so that we can locate the
	// new imports.
	flags := parser.ImportsOnly
	if extra {
		// used all of origData above, use all of it here too
		flags = 0
	}
	fixedData, err := imports.ApplyFixes(fixes, "", src, options, flags)
	if err != nil {
		return nil, err
	}
	if fixedData == nil || fixedData[len(fixedData)-1] != '\n' {
		fixedData = append(fixedData, '\n') // ApplyFixes may miss the newline, go figure.
	}
	edits := diff.Strings(left, string(fixedData))
	return protocolEditsFromSource([]byte(left), edits)
}

// importPrefix returns the prefix of the given file content through the final
// import statement. If there are no imports, the prefix is the package
// statement and any comment groups below it.
func importPrefix(src []byte) (string, error) {
	fset := token.NewFileSet()
	// do as little parsing as possible
	f, err := parser.ParseFile(fset, "", src, parser.ImportsOnly|parser.ParseComments)
	if err != nil { // This can happen if 'package' is misspelled
		return "", fmt.Errorf("importPrefix: failed to parse: %s", err)
	}
	tok := fset.File(f.FileStart)
	var importEnd int
	for _, d := range f.Decls {
		if x, ok := d.(*ast.GenDecl); ok && x.Tok == token.IMPORT {
			if e, err := safetoken.Offset(tok, d.End()); err != nil {
				return "", fmt.Errorf("importPrefix: %s", err)
			} else if e > importEnd {
				importEnd = e
			}
		}
	}

	maybeAdjustToLineEnd := func(pos token.Pos, isCommentNode bool) int {
		offset, err := safetoken.Offset(tok, pos)
		if err != nil {
			return -1
		}

		// Don't go past the end of the file.
		if offset > len(src) {
			offset = len(src)
		}
		// The go/ast package does not account for different line endings, and
		// specifically, in the text of a comment, it will strip out \r\n line
		// endings in favor of \n. To account for these differences, we try to
		// return a position on the next line whenever possible.
		switch line := safetoken.Line(tok, tok.Pos(offset)); {
		case line < tok.LineCount():
			nextLineOffset, err := safetoken.Offset(tok, tok.LineStart(line+1))
			if err != nil {
				return -1
			}
			// If we found a position that is at the end of a line, move the
			// offset to the start of the next line.
			if offset+1 == nextLineOffset {
				offset = nextLineOffset
			}
		case isCommentNode, offset+1 == tok.Size():
			// If the last line of the file is a comment, or we are at the end
			// of the file, the prefix is the entire file.
			offset = len(src)
		}
		return offset
	}
	if importEnd == 0 {
		pkgEnd := f.Name.End()
		importEnd = maybeAdjustToLineEnd(pkgEnd, false)
	}
	for _, cgroup := range f.Comments {
		for _, c := range cgroup.List {
			if end, err := safetoken.Offset(tok, c.End()); err != nil {
				return "", err
			} else if end > importEnd {
				startLine := safetoken.Position(tok, c.Pos()).Line
				endLine := safetoken.Position(tok, c.End()).Line

				// Work around golang/go#41197 by checking if the comment might
				// contain "\r", and if so, find the actual end position of the
				// comment by scanning the content of the file.
				startOffset, err := safetoken.Offset(tok, c.Pos())
				if err != nil {
					return "", err
				}
				if startLine != endLine && bytes.Contains(src[startOffset:], []byte("\r")) {
					if commentEnd := scanForCommentEnd(src[startOffset:]); commentEnd > 0 {
						end = startOffset + commentEnd
					}
				}
				importEnd = maybeAdjustToLineEnd(tok.Pos(end), true)
			}
		}
	}
	if importEnd > len(src) {
		importEnd = len(src)
	}
	return string(src[:importEnd]), nil
}

// scanForCommentEnd returns the offset of the end of the multi-line comment
// at the start of the given byte slice.
func scanForCommentEnd(src []byte) int {
	var s scanner.Scanner
	s.Init(bytes.NewReader(src))
	s.Mode ^= scanner.SkipComments

	t := s.Scan()
	if t == scanner.Comment {
		return s.Pos().Offset
	}
	return 0
}

func computeTextEdits(ctx context.Context, pgf *parsego.File, formatted string) ([]protocol.TextEdit, error) {
	_, done := event.Start(ctx, "golang.computeTextEdits")
	defer done()

	edits := diff.Strings(string(pgf.Src), formatted)
	return protocol.EditsFromDiffEdits(pgf.Mapper, edits)
}

// protocolEditsFromSource converts text edits to LSP edits using the original
// source.
func protocolEditsFromSource(src []byte, edits []diff.Edit) ([]protocol.TextEdit, error) {
	m := protocol.NewMapper("", src)
	var result []protocol.TextEdit
	for _, edit := range edits {
		rng, err := m.OffsetRange(edit.Start, edit.End)
		if err != nil {
			return nil, err
		}

		if rng.Start == rng.End && edit.New == "" {
			// Degenerate case, which may result from a diff tool wanting to delete
			// '\r' in line endings. Filter it out.
			continue
		}
		result = append(result, protocol.TextEdit{
			Range:   rng,
			NewText: edit.New,
		})
	}
	return result, nil
}


================================================
FILE: gopls/internal/golang/format_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
)

func TestImportPrefix(t *testing.T) {
	for i, tt := range []struct {
		input, want string
	}{
		{"package foo", "package foo"},
		{"package foo\n", "package foo\n"},
		{"package foo\n\nfunc f(){}\n", "package foo\n"},
		{"package foo\n\nimport \"fmt\"\n", "package foo\n\nimport \"fmt\""},
		{"package foo\nimport (\n\"fmt\"\n)\n", "package foo\nimport (\n\"fmt\"\n)"},
		{"\n\n\npackage foo\n", "\n\n\npackage foo\n"},
		{"// hi \n\npackage foo //xx\nfunc _(){}\n", "// hi \n\npackage foo //xx\n"},
		{"package foo //hi\n", "package foo //hi\n"},
		{"//hi\npackage foo\n//a\n\n//b\n", "//hi\npackage foo\n//a\n\n//b\n"},
		{
			"package a\n\nimport (\n  \"fmt\"\n)\n//hi\n",
			"package a\n\nimport (\n  \"fmt\"\n)\n//hi\n",
		},
		{`package a /*hi*/`, `package a /*hi*/`},
		{"package main\r\n\r\nimport \"go/types\"\r\n\r\n/*\r\n\r\n */\r\n", "package main\r\n\r\nimport \"go/types\"\r\n\r\n/*\r\n\r\n */\r\n"},
		{"package x; import \"os\"; func f() {}\n\n", "package x; import \"os\""},
		{"package x; func f() {fmt.Println()}\n\n", "package x"},
	} {
		got, err := importPrefix([]byte(tt.input))
		if err != nil {
			t.Fatal(err)
		}
		if d := compare.Text(tt.want, got); d != "" {
			t.Errorf("%d: failed for %q:\n%s", i, tt.input, d)
		}
	}
}

func TestCRLFFile(t *testing.T) {
	for i, tt := range []struct {
		input, want string
	}{
		{
			input: `package main

/*
Hi description
*/
func Hi() {
}
`,
			want: `package main

/*
Hi description
*/`,
		},
	} {
		got, err := importPrefix([]byte(strings.ReplaceAll(tt.input, "\n", "\r\n")))
		if err != nil {
			t.Fatal(err)
		}
		want := strings.ReplaceAll(tt.want, "\n", "\r\n")
		if d := compare.Text(want, got); d != "" {
			t.Errorf("%d: failed for %q:\n%s", i, tt.input, d)
		}
	}
}


================================================
FILE: gopls/internal/golang/freesymbols.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file implements the "Browse free symbols" code action.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"html"
	"slices"
	"sort"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/typesinternal"
)

// FreeSymbolsHTML returns an HTML document containing the report of
// free symbols referenced by the selection.
func FreeSymbolsHTML(viewID string, pkg *cache.Package, pgf *parsego.File, start, end token.Pos, web Web) []byte {

	// Compute free references.
	refs := freeRefs(pkg.Types(), pkg.TypesInfo(), pgf.File, start, end)

	// -- model --

	type Import struct {
		Path    metadata.PackagePath
		Symbols []string
	}
	type Symbol struct {
		Kind string
		Type string
		Refs []types.Object
	}
	var model struct {
		Imported []Import
		PkgLevel []Symbol
		Local    []Symbol
	}

	qualifier := typesinternal.NameRelativeTo(pkg.Types())

	// Populate model.
	{
		// List the refs in order of dotted paths.
		sort.Slice(refs, func(i, j int) bool {
			return refs[i].dotted < refs[j].dotted
		})

		// Inspect the references.
		imported := make(map[string][]*freeRef) // refs to imported symbols, by package path
		seen := make(map[string]bool)           // to de-dup dotted paths
		for _, ref := range refs {
			if seen[ref.dotted] {
				continue // de-dup
			}
			seen[ref.dotted] = true

			var symbols *[]Symbol
			switch ref.scope {
			case "file":
				// imported symbol: group by package
				if pkgname, ok := ref.objects[0].(*types.PkgName); ok {
					path := pkgname.Imported().Path()
					imported[path] = append(imported[path], ref)
				}
				continue
			case "pkg":
				symbols = &model.PkgLevel
			case "local":
				symbols = &model.Local
			default:
				panic(ref.scope)
			}

			// Package and local symbols are presented the same way.
			// We treat each dotted path x.y.z as a separate entity.

			// Compute kind and type of last object (y in obj.x.y).
			typestr := " " + types.TypeString(ref.typ, qualifier)
			var kind string
			switch obj := ref.objects[len(ref.objects)-1].(type) {
			case *types.Var:
				kind = "var"
			case *types.Func:
				kind = "func"
			case *types.TypeName:
				if is[*types.TypeParam](obj.Type()) {
					kind = "type parameter"
				} else {
					kind = "type"
				}
				typestr = "" // avoid "type T T"
			case *types.Const:
				kind = "const"
			case *types.Label:
				kind = "label"
				typestr = "" // avoid "label L L"
			}

			*symbols = append(*symbols, Symbol{
				Kind: kind,
				Type: typestr,
				Refs: ref.objects,
			})
		}

		// Imported symbols.
		// Produce one record per package, with a list of symbols.
		for pkgPath, refs := range moremaps.Sorted(imported) {
			var syms []string
			for _, ref := range refs {
				// strip package name (bytes.Buffer.Len -> Buffer.Len)
				syms = append(syms, ref.dotted[len(ref.objects[0].Name())+len("."):])
			}
			sort.Strings(syms)
			const max = 4
			if len(syms) > max {
				syms[max-1] = fmt.Sprintf("... (%d)", len(syms))
				syms = syms[:max]
			}

			model.Imported = append(model.Imported, Import{
				Path:    PackagePath(pkgPath),
				Symbols: syms,
			})
		}
	}

	// -- presentation --

	var buf bytes.Buffer
	buf.WriteString(`<!DOCTYPE html>
<html>
<head>
<style>
.col-pkg { color: #2eb007 }
.col-file { color: #a10b15 }
.col-local { color: #0cb7c9 }
li { font-family: monospace; }
p { max-width: 6in; }
</style>
  <script src="/assets/common.js"></script>
  <link rel="stylesheet" href="/assets/common.css">
</head>
<body>
<h1>Free symbols</h1>
<p>
  The selected code contains references to these free* symbols:
</p>
`)

	// Present the refs in three sections: imported, same package, local.

	// -- imported symbols --

	// Show one item per package, with a list of symbols.
	fmt.Fprintf(&buf, "<h2><span class='col-file'>⬤</span> Imported symbols</h2>\n")
	fmt.Fprintf(&buf, "<ul>\n")
	for _, imp := range model.Imported {
		fmt.Fprintf(&buf, "<li>import \"<a href='%s'>%s</a>\" // for %s</li>\n",
			web.PkgURL(viewID, imp.Path, ""),
			html.EscapeString(string(imp.Path)),
			strings.Join(imp.Symbols, ", "))
	}
	if len(model.Imported) == 0 {
		fmt.Fprintf(&buf, "<li>(none)</li>\n")
	}
	buf.WriteString("</ul>\n")

	// -- package and local symbols --

	showSymbols := func(scope, title string, symbols []Symbol) {
		fmt.Fprintf(&buf, "<h2><span class='col-%s'>⬤</span> %s</h2>\n", scope, title)
		fmt.Fprintf(&buf, "<ul>\n")
		pre := buf.Len()
		for _, sym := range symbols {
			fmt.Fprintf(&buf, "<li>%s ", sym.Kind) // of rightmost symbol in dotted path
			for i, obj := range sym.Refs {
				if i > 0 {
					buf.WriteByte('.')
				}
				buf.WriteString(objHTML(pkg.FileSet(), web, obj))
			}
			fmt.Fprintf(&buf, " %s</li>\n", html.EscapeString(sym.Type))
		}
		if buf.Len() == pre {
			fmt.Fprintf(&buf, "<li>(none)</li>\n")
		}
		buf.WriteString("</ul>\n")
	}
	showSymbols("pkg", "Package-level symbols", model.PkgLevel)
	showSymbols("local", "Local symbols", model.Local)

	// -- code selection --

	// Print the selection, highlighting references to free symbols.
	buf.WriteString("<hr/>\n")
	sort.Slice(refs, func(i, j int) bool {
		return refs[i].expr.Pos() < refs[j].expr.Pos()
	})
	pos := start
	emitTo := func(end token.Pos) {
		if pos < end {
			fileStart := pgf.File.FileStart
			text := pgf.Mapper.Content[pos-fileStart : end-fileStart]
			buf.WriteString(html.EscapeString(string(text)))
			pos = end
		}
	}
	buf.WriteString(`<pre>`)
	for _, ref := range refs {
		emitTo(ref.expr.Pos())
		fmt.Fprintf(&buf, `<b class='col-%s'>`, ref.scope)
		emitTo(ref.expr.End())
		buf.WriteString(`</b>`)
	}
	emitTo(end)
	buf.WriteString(`</pre>
<hr>
<p>
  *A symbol is "free" if it is referenced within the selection but declared
  outside of it.

  The free variables are approximately the set of parameters that
  would be needed if the block were extracted into its own function in
  the same package.

  Free identifiers may include local types and control labels as well.

  Even when you don't intend to extract a block into a new function,
  this information can help you to tell at a glance what names a block
  of code depends on.
</p>
<p>
  Each dotted path of identifiers (such as file.Name.Pos) is reported
  as a separate item, so that you can see which parts of a complex
  type are actually needed.

  The free symbols referenced by the body of a function may
  reveal that only a small part (a single field of a struct, say) of
  one of the function's parameters is used, allowing you to simplify
  and generalize the function by choosing a different type for that
  parameter.
</p>
`)
	return buf.Bytes()
}

// A freeRef records a reference to a dotted path obj.x.y,
// where obj (=objects[0]) is a free symbol.
type freeRef struct {
	objects []types.Object // [obj x y]
	dotted  string         // "obj.x.y"  (used as sort key)
	scope   string         // scope of obj: pkg|file|local
	expr    ast.Expr       // =*Ident|*SelectorExpr
	typ     types.Type     // type of obj.x.y
}

// freeRefs returns the list of references to free symbols (from
// within the selection to a symbol declared outside of it).
// It uses only info.{Scopes,Types,Uses}.
func freeRefs(pkg *types.Package, info *types.Info, file *ast.File, start, end token.Pos) []*freeRef {
	// Keep us honest about which fields we access.
	info = &types.Info{
		Scopes: info.Scopes,
		Types:  info.Types,
		Uses:   info.Uses,
	}

	fileScope := info.Scopes[file]
	pkgScope := fileScope.Parent()

	// id is called for the leftmost id x in each dotted chain such as (x.y).z.
	// suffix is the reversed suffix of selections (e.g. [z y]).
	id := func(n *ast.Ident, suffix []types.Object) *freeRef {
		obj := info.Uses[n]
		if obj == nil {
			return nil // not a reference
		}
		if start <= obj.Pos() && obj.Pos() < end {
			return nil // defined within selection => not free
		}
		parent := obj.Parent()

		// Compute dotted path.
		objects := append(suffix, obj)
		if obj.Pkg() != nil && obj.Pkg() != pkg && typesinternal.IsPackageLevel(obj) { // dot import
			// Synthesize the implicit PkgName.
			pkgName := types.NewPkgName(token.NoPos, pkg, obj.Pkg().Name(), obj.Pkg())
			parent = fileScope
			objects = append(objects, pkgName)
		}
		slices.Reverse(objects)
		var dotted strings.Builder
		for i, obj := range objects {
			if obj == nil {
				return nil // type error
			}
			if i > 0 {
				dotted.WriteByte('.')
			}
			dotted.WriteString(obj.Name())
		}

		// Compute scope of base object.
		var scope string
		switch parent {
		case nil:
			return nil // interface method or struct field
		case types.Universe:
			return nil // built-in (not interesting)
		case fileScope:
			scope = "file" // defined at file scope (imported package)
		case pkgScope:
			scope = "pkg" // defined at package level
		default:
			scope = "local" // defined within current function
		}

		return &freeRef{
			objects: objects,
			dotted:  dotted.String(),
			scope:   scope,
		}
	}

	// sel(x.y.z, []) calls sel(x.y, [z]) calls id(x, [z, y]).
	sel := func(sel *ast.SelectorExpr, suffix []types.Object) *freeRef {
		for {
			suffix = append(suffix, info.Uses[sel.Sel])

			switch x := ast.Unparen(sel.X).(type) {
			case *ast.Ident:
				return id(x, suffix)
			default:
				return nil
			case *ast.SelectorExpr:
				sel = x
			}
		}
	}

	// Visit all the identifiers in the selected ASTs.
	var free []*freeRef
	path, _ := astutil.PathEnclosingInterval(file, start, end)
	var visit func(n ast.Node) bool
	visit = func(n ast.Node) bool {
		// Is this node contained within the selection?
		// (freesymbols permits inexact selections,
		// like two stmts in a block.)
		if n != nil && start <= n.Pos() && n.End() <= end {
			var ref *freeRef
			switch n := n.(type) {
			case *ast.Ident:
				ref = id(n, nil)
			case *ast.SelectorExpr:
				ref = sel(n, nil)
			}

			if ref != nil {
				ref.expr = n.(ast.Expr)
				if tv, ok := info.Types[ref.expr]; ok {
					ref.typ = tv.Type
				} else {
					ref.typ = types.Typ[types.Invalid]
				}
				free = append(free, ref)
			}

			// After visiting x.sel, don't descend into sel.
			// Descend into x only if we didn't get a ref for x.sel.
			if sel, ok := n.(*ast.SelectorExpr); ok {
				if ref == nil {
					ast.Inspect(sel.X, visit)
				}
				return false
			}
		}

		return true // descend
	}
	ast.Inspect(path[0], visit)
	return free
}

// objHTML returns HTML for obj.Name(), possibly marked up as a link
// to the web server that, when visited, opens the declaration in the
// client editor.
func objHTML(fset *token.FileSet, web Web, obj types.Object) string {
	text := obj.Name()
	if posn := safetoken.StartPosition(fset, obj.Pos()); posn.IsValid() {
		url := web.SrcURL(posn.Filename, posn.Line, posn.Column)
		return sourceLink(text, url)
	}
	return text
}

// sourceLink returns HTML for a link to open a file in the client editor.
func sourceLink(text, url string) string {
	// The /src URL returns nothing but has the side effect
	// of causing the LSP client to open the requested file.
	// So we use onclick to prevent the browser from navigating.
	// We keep the href attribute as it causes the <a> to render
	// as a link: blue, underlined, with URL hover information.
	return fmt.Sprintf(`<a href="%[1]s" onclick='return httpGET("%[1]s")'>%[2]s</a>`,
		html.EscapeString(url), text)
}


================================================
FILE: gopls/internal/golang/freesymbols_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"reflect"
	"runtime"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
)

// TestFreeRefs is a unit test of the free-references algorithm.
func TestFreeRefs(t *testing.T) {
	if runtime.GOOS == "js" || runtime.GOARCH == "wasm" {
		t.Skip("some test imports are unsupported on js or wasm")
	}

	for i, test := range []struct {
		src  string
		want []string // expected list of "scope kind dotted-path" triples
	}{
		{
			// basic example (has a "cannot infer" type error)
			`package p; func f[T ~int](x any) { var y T; « f(x.(T) + y) » }`,
			[]string{"pkg func f", "local var x", "local typename T", "local var y"},
		},
		{
			// selection need not be tree-aligned
			`package p; type T int; type U « T; func _(x U) »`,
			[]string{"pkg typename T", "pkg typename U"},
		},
		{
			// imported symbols
			`package p; import "fmt"; func f() { « var x fmt.Stringer » }`,
			[]string{"file pkgname fmt.Stringer"},
		},
		{
			// unsafe and error, our old nemeses
			`package p; import "unsafe"; var ( « _  unsafe.Pointer; _ = error(nil).Error »; )`,
			[]string{"file pkgname unsafe.Pointer"},
		},
		{
			// two attributes of a var, but not the var itself
			`package p; import "bytes"; func _(buf bytes.Buffer) { « buf.WriteByte(0); buf.WriteString(""); » }`,
			[]string{"local var buf.WriteByte", "local var buf.WriteString"},
		},
		{
			// dot imports (an edge case)
			`package p; import . "errors"; var _ = « New»`,
			[]string{"file pkgname errors.New"},
		},
		{
			// struct field (regression test for overzealous dot import logic)
			`package p; import "net/url"; var _ = «url.URL{Host: ""}»`,
			[]string{"file pkgname url.URL"},
		},
		{
			// dot imports (another regression test of same)
			`package p; import . "net/url"; var _ = «URL{Host: ""}»`,
			[]string{"file pkgname url.URL"},
		},
		{
			// dot import of unsafe (a corner case)
			`package p; import . "unsafe"; var _ « Pointer»`,
			[]string{"file pkgname unsafe.Pointer"},
		},
		{
			// dotted path
			`package p; import "go/build"; var _ = « build.Default.GOOS »`,
			[]string{"file pkgname build.Default.GOOS"},
		},
		{
			// type error
			`package p; import "nope"; var _ = « nope.nope.nope »`,
			[]string{"file pkgname nope"},
		},
	} {
		name := fmt.Sprintf("file%d.go", i)
		t.Run(name, func(t *testing.T) {
			fset := token.NewFileSet()
			startOffset := strings.Index(test.src, "«")
			endOffset := strings.Index(test.src, "»")
			if startOffset < 0 || endOffset < startOffset {
				t.Fatalf("invalid «...» selection (%d:%d)", startOffset, endOffset)
			}
			src := test.src[:startOffset] +
				" " +
				test.src[startOffset+len("«"):endOffset] +
				" " +
				test.src[endOffset+len("»"):]
			f, err := parser.ParseFile(fset, name, src, parser.SkipObjectResolution)
			if err != nil {
				t.Fatal(err)
			}
			conf := &types.Config{
				Importer: importer.Default(),
				Error:    func(err error) { t.Log(err) }, // not fatal
			}
			info := &types.Info{
				Uses:   make(map[*ast.Ident]types.Object),
				Scopes: make(map[ast.Node]*types.Scope),
				Types:  make(map[ast.Expr]types.TypeAndValue),
			}
			pkg, _ := conf.Check(f.Name.Name, fset, []*ast.File{f}, info) // ignore errors
			tf := fset.File(f.Package)
			refs := freeRefs(pkg, info, f, tf.Pos(startOffset), tf.Pos(endOffset))

			kind := func(obj types.Object) string { // e.g. "var", "const"
				return strings.ToLower(reflect.TypeOf(obj).Elem().Name())
			}

			var got []string
			for _, ref := range refs {
				msg := ref.scope + " " + kind(ref.objects[0]) + " " + ref.dotted
				got = append(got, msg)
			}
			if diff := cmp.Diff(test.want, got); diff != "" {
				t.Errorf("(-want +got)\n%s", diff)
			}
		})
	}
}


================================================
FILE: gopls/internal/golang/highlight.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strconv"
	"strings"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/fmtstr"
	"golang.org/x/tools/internal/moreiters"
)

func Highlight(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.DocumentHighlight, error) {
	ctx, done := event.Start(ctx, "golang.Highlight")
	defer done()

	// We always want fully parsed files for highlight, regardless
	// of whether the file belongs to a workspace package.
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, fmt.Errorf("getting package for Highlight: %w", err)
	}

	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}

	cur, _, _, _ := astutil.Select(pgf.Cursor(), start, end) // can't fail: pgf contains pos

	result, err := highlightPath(pkg.TypesInfo(), cur, start, end)
	if err != nil {
		return nil, err
	}
	var ranges []protocol.DocumentHighlight
	for rng, kind := range result {
		rng, err := pgf.NodeRange(rng)
		if err != nil {
			return nil, err
		}
		ranges = append(ranges, protocol.DocumentHighlight{
			Range: rng,
			Kind:  kind,
		})
	}
	return ranges, nil
}

// highlightPath returns ranges to highlight for the given the cursor.
func highlightPath(info *types.Info, cur inspector.Cursor, start, end token.Pos) (map[astutil.Range]protocol.DocumentHighlightKind, error) {
	result := make(map[astutil.Range]protocol.DocumentHighlightKind)

	// Inside a call to a printf-like function (as identified
	// by a simple heuristic).
	// Treat each corresponding ("%v", arg) pair as a highlight class.
	for node := range cur.Enclosing((*ast.CallExpr)(nil)) {
		call := node.Node().(*ast.CallExpr)
		lit, idx := formatStringAndIndex(info, call)
		if idx != -1 {
			highlightPrintf(call, idx, start, end, lit, result)
		}
	}

	switch node := cur.Node().(type) {
	case *ast.BasicLit:
		// Import path string literal?
		if imp, ok := cur.Parent().Node().(*ast.ImportSpec); ok {
			highlight := func(n ast.Node) {
				highlightNode(result, n, protocol.Text)
			}

			// Highlight the import itself...
			highlight(imp)

			// ...and all references to it in the file.
			if pkgname := info.PkgNameOf(imp); pkgname != nil {
				_, curFile := cursorutil.FirstEnclosing[*ast.File](cur)
				for c := range curFile.Preorder((*ast.Ident)(nil)) {
					if id := c.Node().(*ast.Ident); info.Uses[id] == pkgname {
						highlight(id)
					}
				}
			}
			return result, nil
		}
		highlightFuncControlFlow(cur, result)
	case *ast.ReturnStmt, *ast.FuncDecl, *ast.FuncType:
		highlightFuncControlFlow(cur, result)
	case *ast.Ident:
		// Check if ident is inside return or func decl.
		highlightFuncControlFlow(cur, result)
		highlightIdentifier(cur, info, result)
	case *ast.ForStmt, *ast.RangeStmt:
		var label *ast.Ident
		if l, ok := cur.Parent().Node().(*ast.LabeledStmt); ok {
			label = l.Label
		}
		highlightLoopControlFlow(node, label, info, result)
	case *ast.SwitchStmt, *ast.TypeSwitchStmt:
		var label *ast.Ident
		if l, ok := cur.Parent().Node().(*ast.LabeledStmt); ok {
			label = l.Label
		}
		highlightSwitchFlow(node, label, info, result)
	case *ast.BranchStmt:
		// BREAK can exit a loop, switch or select, while CONTINUE exit a loop so
		// these need to be handled separately. They can also be embedded in any
		// other loop/switch/select if they have a label. TODO: add support for
		// GOTO and FALLTHROUGH as well.
		switch node.Tok {
		case token.BREAK:
			if node.Label != nil {
				highlightLabeledFlow(cur, info, result)
			} else {
				highlightUnlabeledBreakFlow(cur, info, result)
			}
		case token.CONTINUE:
			if node.Label != nil {
				highlightLabeledFlow(cur, info, result)
			} else {
				var (
					stmt  ast.Node
					label *ast.Ident
				)
				if curLoop, ok := moreiters.First(cur.Enclosing((*ast.ForStmt)(nil), (*ast.RangeStmt)(nil))); ok {
					stmt = curLoop.Node()
					if l, ok := curLoop.Parent().Node().(*ast.LabeledStmt); ok {
						label = l.Label
					}
				}
				highlightLoopControlFlow(stmt, label, info, result)
			}
		}
	}

	return result, nil
}

// formatStringAndIndex returns the BasicLit and index of the BasicLit (the last
// non-variadic parameter) within the given printf-like call
// expression, returns -1 as index if unknown.
func formatStringAndIndex(info *types.Info, call *ast.CallExpr) (*ast.BasicLit, int) {
	typ := info.Types[call.Fun].Type
	if typ == nil {
		return nil, -1 // missing type
	}
	sig, ok := typ.(*types.Signature)
	if !ok {
		return nil, -1 // ill-typed
	}
	if !sig.Variadic() {
		// Skip checking non-variadic functions.
		return nil, -1
	}
	idx := sig.Params().Len() - 2
	if !(0 <= idx && idx < len(call.Args)) {
		// Skip checking functions without a format string parameter, or
		// missing the corresponding format argument.
		return nil, -1
	}
	// We only care about literal format strings, so fmt.Sprint("a"+"b%s", "bar") won't be highlighted.
	if lit, ok := call.Args[idx].(*ast.BasicLit); ok && lit.Kind == token.STRING {
		return lit, idx
	}
	return nil, -1
}

// highlightPrintf highlights operations in a format string and their
// corresponding variadic arguments in a (possible) printf-style function call.
// For example:
//
// fmt.Printf("Hello %s, you scored %d", name, score)
//
// If the cursor is on %s or name, it will highlight %s as a write operation,
// and name as a read operation.
func highlightPrintf(call *ast.CallExpr, idx int, start, end token.Pos, lit *ast.BasicLit, result map[astutil.Range]protocol.DocumentHighlightKind) {
	format, err := strconv.Unquote(lit.Value)
	if err != nil {
		return
	}
	if !strings.Contains(format, "%") {
		return
	}
	operations, err := fmtstr.Parse(format, idx)
	if err != nil {
		return
	}

	// fmt.Printf("%[1]d %[1].2d", 3)
	//
	// When cursor is in `%[1]d`, we record `3` being successfully highlighted.
	// And because we will also record `%[1].2d`'s corresponding arguments index is `3`
	// in `visited`, even though it will not highlight any item in the first pass,
	// in the second pass we can correctly highlight it. So the three are the same class.
	succeededArg := 0
	visited := make(map[astutil.Range]int, 0)

	// highlightPair highlights the operation and its potential argument pair if the cursor is within either range.
	highlightPair := func(rang fmtstr.Range, argIndex int) {
		var (
			rng       astutil.Range
			withinRng bool
		)
		rng, err = astutil.RangeInStringLiteral(lit, rang.Start, rang.End)
		if err != nil {
			return
		}
		visited[rng] = argIndex

		if start == end {
			// End pos can't equal to range's end, otherwise the two neighborhood
			// such as (%[2]*d) are both highlighted if cursor in "d" (ending of [2]*).
			withinRng = rng.Start <= start && end < rng.End()
		} else {
			// With a non-empty selection, there is no ambiguity.
			withinRng = rng.Contains(astutil.RangeOf(start, end))
		}

		var (
			arg       ast.Expr
			withinArg bool
		)
		if argIndex < len(call.Args) {
			arg = call.Args[argIndex]
			withinArg = astutil.NodeContains(arg, astutil.RangeOf(start, end))
		}

		if withinRng || withinArg {
			highlightRange(result, rng, protocol.Write)
			if arg != nil {
				succeededArg = argIndex
				highlightNode(result, arg, protocol.Read)
			}
		}
	}

	for _, op := range operations {
		// If width or prec has any *, we can not highlight the full range from % to verb,
		// because it will overlap with the sub-range of *, for example:
		//
		// fmt.Printf("%*[3]d", 4, 5, 6)
		//               ^  ^ we can only highlight this range when cursor in 6. '*' as a one-rune range will
		//               highlight for 4.
		hasAsterisk := false

		// Try highlight Width if there is a *.
		if op.Width.Dynamic != -1 {
			hasAsterisk = true
			highlightPair(op.Width.Range, op.Width.Dynamic)
		}

		// Try highlight Precision if there is a *.
		if op.Prec.Dynamic != -1 {
			hasAsterisk = true
			highlightPair(op.Prec.Range, op.Prec.Dynamic)
		}

		// Try highlight Verb.
		if op.Verb.Verb != '%' {
			// If any * is found inside operation, narrow the highlight range.
			if hasAsterisk {
				highlightPair(op.Verb.Range, op.Verb.ArgIndex)
			} else {
				highlightPair(op.Range, op.Verb.ArgIndex)
			}
		}
	}

	// Second pass, try to highlight those missed operations.
	for rng, argIndex := range visited {
		if succeededArg == argIndex {
			highlightRange(result, rng, protocol.Write)
		}
	}
}

// highlightFuncControlFlow adds highlight ranges to the result map to
// associate results and result parameters.
//
// Specifically, if the cursor is in a result or result parameter, all
// results and result parameters with the same index are highlighted. If the
// cursor is in a 'func' or 'return' keyword, the func keyword as well as all
// returns from that func are highlighted.
//
// As a special case, if the cursor is within a complicated expression, control
// flow highlighting is disabled, as it would highlight too much.
func highlightFuncControlFlow(cur inspector.Cursor, result map[astutil.Range]protocol.DocumentHighlightKind) {

	var (
		funcType   *ast.FuncType   // type of enclosing func, or nil
		funcBody   *ast.BlockStmt  // body of enclosing func, or nil
		returnStmt *ast.ReturnStmt // enclosing ReturnStmt within the func, or nil
	)

loop:
	for cur := range cur.Enclosing() {
		switch n := cur.Node().(type) {
		// TODO(rfindley, low priority): these pre-existing cases for KeyValueExpr
		// and CallExpr appear to avoid highlighting when the cursor is in a
		// complicated expression. However, the basis for this heuristic is
		// unclear. Can we formalize a rationale?
		case *ast.KeyValueExpr:
			// If cursor is in a key: value expr, we don't want control flow highlighting.
			return

		case *ast.FuncLit:
			funcType = n.Type
			funcBody = n.Body
			break loop

		case *ast.FuncDecl:
			funcType = n.Type
			funcBody = n.Body
			break loop

		case *ast.ReturnStmt:
			returnStmt = n
		}

		// If cursor is an arg in a callExpr, we don't want control flow highlighting.
		if cur.ParentEdgeKind() == edge.CallExpr_Args {
			return
		}
	}

	if funcType == nil {
		return // cursor is not in a function
	}

	// Helper functions for inspecting the current location.
	var (
		pos    = cur.Node().Pos()
		inSpan = func(start, end token.Pos) bool { return start <= pos && pos < end }
		inNode = func(n ast.Node) bool { return inSpan(n.Pos(), n.End()) }
	)

	inResults := funcType.Results != nil && inNode(funcType.Results)

	// If the cursor is on a "return" or "func" keyword, but not highlighting any
	// specific field or expression, we should highlight all of the exit points
	// of the function, including the "return" and "func" keywords.
	funcEnd := funcType.Func + token.Pos(len("func"))
	highlightAll := cur.Node() == returnStmt || inSpan(funcType.Func, funcEnd)
	var highlightIndexes map[int]bool

	if highlightAll {
		// Add the "func" part of the func declaration.
		highlightRange(result, astutil.RangeOf(funcType.Func, funcEnd), protocol.Text)
	} else if returnStmt == nil && !inResults {
		return // nothing to highlight
	} else {
		// If we're not highlighting the entire return statement, we need to collect
		// specific result indexes to highlight. This may be more than one index if
		// the cursor is on a multi-name result field, but not in any specific name.
		if !highlightAll {
			highlightIndexes = make(map[int]bool)
			if returnStmt != nil {
				for i, n := range returnStmt.Results {
					if inNode(n) {
						highlightIndexes[i] = true
						break
					}
				}
			}

			if funcType.Results != nil {
				// Scan fields, either adding highlights according to the highlightIndexes
				// computed above, or accounting for the cursor position within the result
				// list.
				// (We do both at once to avoid repeating the cumbersome field traversal.)
				i := 0
			findField:
				for _, field := range funcType.Results.List {
					for j, name := range field.Names {
						if inNode(name) || highlightIndexes[i+j] {
							highlightNode(result, name, protocol.Text)
							highlightIndexes[i+j] = true
							break findField // found/highlighted the specific name
						}
					}
					// If the cursor is in a field but not in a name (e.g. in the space, or
					// the type), highlight the whole field.
					//
					// Note that this may not be ideal if we're at e.g.
					//
					//  (x,‸y int, z int8)
					//
					// ...where it would make more sense to highlight only y. But we don't
					// reach this function if not in a func, return, ident, or basiclit.
					if inNode(field) || highlightIndexes[i] {
						highlightNode(result, field, protocol.Text)
						highlightIndexes[i] = true
						if inNode(field) {
							for j := range field.Names {
								highlightIndexes[i+j] = true
							}
						}
						break findField // found/highlighted the field
					}

					n := len(field.Names)
					if n == 0 {
						n = 1
					}
					i += n
				}
			}
		}
	}

	if funcBody != nil {
		ast.Inspect(funcBody, func(n ast.Node) bool {
			switch n := n.(type) {
			case *ast.FuncDecl, *ast.FuncLit:
				// Don't traverse into any functions other than enclosingFunc.
				return false
			case *ast.ReturnStmt:
				if highlightAll {
					// Add the entire return statement.
					highlightNode(result, n, protocol.Text)
				} else {
					// Add the highlighted indexes.
					for i, expr := range n.Results {
						if highlightIndexes[i] {
							highlightNode(result, expr, protocol.Text)
						}
					}
				}
				return false

			}
			return true
		})
	}
}

// highlightUnlabeledBreakFlow highlights the innermost enclosing
// for/range/switch or select
func highlightUnlabeledBreakFlow(cur inspector.Cursor, info *types.Info, result map[astutil.Range]protocol.DocumentHighlightKind) {
	// Reverse walk the path until we find closest loop, select, or switch.
	for cur := range cur.Enclosing() {
		switch n := cur.Node().(type) {
		case *ast.ForStmt, *ast.RangeStmt:
			var label *ast.Ident
			if l, ok := cur.Parent().Node().(*ast.LabeledStmt); ok {
				label = l.Label
			}
			highlightLoopControlFlow(n, label, info, result)
			return // only highlight the innermost statement
		case *ast.SwitchStmt, *ast.TypeSwitchStmt:
			var label *ast.Ident
			if l, ok := cur.Parent().Node().(*ast.LabeledStmt); ok {
				label = l.Label
			}
			highlightSwitchFlow(n, label, info, result)
			return
		case *ast.SelectStmt:
			// TODO: add highlight when breaking a select.
			return
		}
	}
}

// highlightLabeledFlow highlights the enclosing labeled for, range,
// or switch statement denoted by a labeled break or continue stmt.
//
// The input cursor must point to a [ast.BranchStmt]
func highlightLabeledFlow(curBranch inspector.Cursor, info *types.Info, result map[astutil.Range]protocol.DocumentHighlightKind) {
	use := info.Uses[curBranch.Node().(*ast.BranchStmt).Label]
	if use == nil {
		return
	}
	for cur := range curBranch.Enclosing((*ast.LabeledStmt)(nil)) {
		if label := cur.Node().(*ast.LabeledStmt); info.Defs[label.Label] == use {
			switch label.Stmt.(type) {
			case *ast.ForStmt, *ast.RangeStmt:
				highlightLoopControlFlow(label.Stmt, label.Label, info, result)
			case *ast.SwitchStmt, *ast.TypeSwitchStmt:
				highlightSwitchFlow(label.Stmt, label.Label, info, result)
			}
			return
		}
	}
}

func highlightLoopControlFlow(loop ast.Node, label *ast.Ident, info *types.Info, result map[astutil.Range]protocol.DocumentHighlightKind) {
	// Add the for statement.
	rngStart := loop.Pos()
	rngEnd := loop.Pos() + token.Pos(len("for"))
	highlightRange(result, astutil.RangeOf(rngStart, rngEnd), protocol.Text)

	// Traverse AST to find branch statements within the same for-loop.
	ast.Inspect(loop, func(n ast.Node) bool {
		switch n.(type) {
		case *ast.ForStmt, *ast.RangeStmt:
			return loop == n
		case *ast.SwitchStmt, *ast.TypeSwitchStmt, *ast.SelectStmt:
			return false
		}
		b, ok := n.(*ast.BranchStmt)
		if !ok {
			return true
		}
		if b.Label == nil || info.Uses[b.Label] == info.Defs[label] {
			highlightNode(result, b, protocol.Text)
		}
		return true
	})

	// Find continue statements in the same loop or switches/selects.
	ast.Inspect(loop, func(n ast.Node) bool {
		switch n.(type) {
		case *ast.ForStmt, *ast.RangeStmt:
			return loop == n
		}

		if n, ok := n.(*ast.BranchStmt); ok && n.Tok == token.CONTINUE {
			highlightNode(result, n, protocol.Text)
		}
		return true
	})

	// We don't need to check other for loops if we aren't looking for labeled statements.
	if label == nil {
		return
	}

	// Find labeled branch statements in any loop.
	ast.Inspect(loop, func(n ast.Node) bool {
		b, ok := n.(*ast.BranchStmt)
		if !ok {
			return true
		}
		// statement with labels that matches the loop
		if b.Label != nil && info.Uses[b.Label] == info.Defs[label] {
			highlightNode(result, b, protocol.Text)
		}
		return true
	})
}

func highlightSwitchFlow(node ast.Node, label *ast.Ident, info *types.Info, result map[astutil.Range]protocol.DocumentHighlightKind) {
	// Add the switch statement.
	rngStart := node.Pos()
	rngEnd := node.Pos() + token.Pos(len("switch"))
	highlightRange(result, astutil.RangeOf(rngStart, rngEnd), protocol.Text)

	// Traverse AST to find break statements within the same switch.
	ast.Inspect(node, func(n ast.Node) bool {
		switch n.(type) {
		case *ast.SwitchStmt, *ast.TypeSwitchStmt:
			return node == n
		case *ast.ForStmt, *ast.RangeStmt, *ast.SelectStmt:
			return false
		}

		b, ok := n.(*ast.BranchStmt)
		if !ok || b.Tok != token.BREAK {
			return true
		}

		if b.Label == nil || info.Uses[b.Label] == info.Defs[label] {
			highlightNode(result, b, protocol.Text)
		}
		return true
	})

	// We don't need to check other switches if we aren't looking for labeled statements.
	if label == nil {
		return
	}

	// Find labeled break statements in any switch
	ast.Inspect(node, func(n ast.Node) bool {
		b, ok := n.(*ast.BranchStmt)
		if !ok || b.Tok != token.BREAK {
			return true
		}

		if b.Label != nil && info.Uses[b.Label] == info.Defs[label] {
			highlightNode(result, b, protocol.Text)
		}

		return true
	})
}

func highlightNode(result map[astutil.Range]protocol.DocumentHighlightKind, n ast.Node, kind protocol.DocumentHighlightKind) {
	highlightRange(result, astutil.NodeRange(n), kind)
}

func highlightRange(result map[astutil.Range]protocol.DocumentHighlightKind, rng astutil.Range, kind protocol.DocumentHighlightKind) {
	// Order of traversal is important: some nodes (e.g. identifiers) are
	// visited more than once, but the kind set during the first visitation "wins".
	if _, exists := result[rng]; !exists {
		result[rng] = kind
	}
}

func highlightIdentifier(cur inspector.Cursor, info *types.Info, result map[astutil.Range]protocol.DocumentHighlightKind) {
	ident := cur.Node().(*ast.Ident)

	// obj may be nil if the Ident is undefined.
	// In this case, the behavior expected by tests is
	// to match other undefined Idents of the same name.
	obj := info.ObjectOf(ident)

	highlightIdent := func(n *ast.Ident, kind protocol.DocumentHighlightKind) {
		if n.Name == ident.Name && info.ObjectOf(n) == obj {
			highlightNode(result, n, kind)
		}
	}
	// highlightWriteInExpr is called for expressions that are
	// logically on the left side of an assignment.
	// We follow the behavior of VSCode+Rust and GoLand, which differs
	// slightly from types.TypeAndValue.Assignable:
	//     *ptr = 1       // ptr write
	//     *ptr.field = 1 // ptr read, field write
	//     s.field = 1    // s read, field write
	//     array[i] = 1   // array read
	var highlightWriteInExpr func(expr ast.Expr)
	highlightWriteInExpr = func(expr ast.Expr) {
		switch expr := expr.(type) {
		case *ast.Ident:
			highlightIdent(expr, protocol.Write)
		case *ast.SelectorExpr:
			highlightIdent(expr.Sel, protocol.Write)
		case *ast.StarExpr:
			highlightWriteInExpr(expr.X)
		case *ast.ParenExpr:
			highlightWriteInExpr(expr.X)
		}
	}

	_, curFile := cursorutil.FirstEnclosing[*ast.File](cur)
	curFile.Inspect(nil, func(c inspector.Cursor) bool {
		switch n := c.Node().(type) {
		case *ast.AssignStmt:
			for _, s := range n.Lhs {
				highlightWriteInExpr(s)
			}
		case *ast.GenDecl:
			if n.Tok == token.CONST || n.Tok == token.VAR {
				for _, spec := range n.Specs {
					if spec, ok := spec.(*ast.ValueSpec); ok {
						for _, ele := range spec.Names {
							highlightWriteInExpr(ele)
						}
					}
				}
			}
		case *ast.IncDecStmt:
			highlightWriteInExpr(n.X)
		case *ast.SendStmt:
			highlightWriteInExpr(n.Chan)
		case *ast.CompositeLit:
			t := info.TypeOf(n)
			if t == nil {
				t = types.Typ[types.Invalid]
			}
			if ptr, ok := t.Underlying().(*types.Pointer); ok {
				t = ptr.Elem()
			}
			if _, ok := t.Underlying().(*types.Struct); ok {
				for _, expr := range n.Elts {
					if expr, ok := (expr).(*ast.KeyValueExpr); ok {
						highlightWriteInExpr(expr.Key)
					}
				}
			}
		case *ast.RangeStmt:
			highlightWriteInExpr(n.Key)
			highlightWriteInExpr(n.Value)
		case *ast.Field:
			for _, name := range n.Names {
				highlightIdent(name, protocol.Text)
			}
		case *ast.Ident:
			// This case is reached for all Idents,
			// including those also visited by highlightWriteInExpr.
			if is[*types.Var](info.ObjectOf(n)) {
				highlightIdent(n, protocol.Read)
			} else {
				// kind of idents in PkgName, etc. is Text
				highlightIdent(n, protocol.Text)
			}
		case *ast.ImportSpec:
			pkgname := info.PkgNameOf(n)
			if obj != nil && pkgname == obj {
				if n.Name != nil {
					highlightNode(result, n.Name, protocol.Text)
				} else {
					highlightNode(result, n, protocol.Text)
				}
			}
		}
		return true
	})
}


================================================
FILE: gopls/internal/golang/hover.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"go/ast"
	"go/constant"
	"go/doc"
	"go/format"
	"go/printer"
	"go/token"
	"go/types"
	"go/version"
	"io/fs"
	"path/filepath"
	"slices"
	"sort"
	"strconv"
	"strings"
	"text/tabwriter"
	"time"
	"unicode/utf8"

	"golang.org/x/text/unicode/runenames"
	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

// hoverResult contains the (internal) result of a hover query.
// It is formatted in one of several formats as determined by the
// HoverKind setting.
type hoverResult struct {
	// The fields below are exported to define the JSON hover format.
	// TODO(golang/go#70233): (re)remove support for JSON hover.

	// Synopsis is a single sentence Synopsis of the symbol's documentation.
	//
	// TODO(adonovan): in what syntax? It (usually) comes from doc.Synopsis,
	// which produces "Text" form, but it may be fed to
	// DocCommentToMarkdown, which expects doc comment syntax.
	Synopsis string `json:"synopsis"`

	// FullDocumentation is the symbol's full documentation.
	FullDocumentation string `json:"fullDocumentation"`

	// Signature is the symbol's Signature.
	Signature string `json:"signature"`

	// SingleLine is a single line describing the symbol.
	// This is recommended only for use in clients that show a single line for hover.
	SingleLine string `json:"singleLine"`

	// SymbolName is the human-readable name to use for the symbol in links.
	SymbolName string `json:"symbolName"`

	// LinkPath is the path of the package enclosing the given symbol,
	// with the module portion (if any) replaced by "module@version".
	//
	// For example: "github.com/google/go-github/v48@v48.1.0/github".
	//
	// Use LinkTarget + "/" + LinkPath + "#" + LinkAnchor to form a pkgsite URL.
	LinkPath string `json:"linkPath"`

	// LinkAnchor is the pkg.go.dev link anchor for the given symbol.
	// For example, the "Node" part of "pkg.go.dev/go/ast#Node".
	LinkAnchor string `json:"linkAnchor"`

	// New fields go below, and are unexported. The existing
	// exported fields are underspecified and have already
	// constrained our movements too much. A detailed JSON
	// interface might be nice, but it needs a design and a
	// precise specification.
	// TODO(golang/go#70233): (re)deprecate the JSON hover output.

	// typeDecl is the declaration syntax for a type,
	// or "" for a non-type.
	typeDecl string

	// methods is the list of descriptions of methods of a type,
	// omitting any that are obvious from typeDecl.
	// It is "" for a non-type.
	methods string

	// promotedFields is the list of descriptions of accessible
	// fields of a (struct) type that were promoted through an
	// embedded field.
	promotedFields string

	// footer is additional content to insert at the bottom of the hover
	// documentation, before the pkgdoc link.
	footer string
}

// Hover implements the "textDocument/hover" RPC for Go files.
// It may return nil even on success.
//
// If pkgURL is non-nil, it should be used to generate doc links.
func Hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range, pkgURL func(path PackagePath, fragment string) protocol.URI) (*protocol.Hover, error) {
	ctx, done := event.Start(ctx, "golang.Hover")
	defer done()

	rng, h, err := hover(ctx, snapshot, fh, rng)
	if err != nil {
		return nil, err
	}
	if h == nil {
		return nil, nil
	}
	hover, err := formatHover(h, snapshot.Options(), pkgURL)
	if err != nil {
		return nil, err
	}
	return &protocol.Hover{
		Contents: protocol.MarkupContent{
			Kind:  snapshot.Options().PreferredContentFormat,
			Value: hover,
		},
		Range: rng,
	}, nil
}

// findRhsTypeDecl finds an alias's rhs type and returns its declaration.
// The rhs of an alias might be an alias as well, but we feel this is a rare case.
// It returns an empty string if the given obj is not an alias.
func findRhsTypeDecl(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, obj types.Object) (string, error) {
	if alias, ok := obj.Type().(*types.Alias); ok {
		// we choose Rhs instead of types.Unalias to make the connection between original alias
		// and the corresponding aliased type clearer.
		// types.Unalias brings confusion because it breaks the connection from A to C given
		// the alias chain like 'type ( A = B; B = C; )' except we show all transitive alias
		// from start to the end. As it's rare, we don't do so.
		if named, ok := alias.Rhs().(*types.Named); ok {
			obj = named.Obj()
			declPGF1, declPos1, err := parseFull(ctx, snapshot, pkg.FileSet(), obj)
			if err != nil {
				return "", err
			}
			realTypeDecl, _, err := typeDeclContent(declPGF1, declPos1, obj.Name())
			return realTypeDecl, err
		}
	}

	return "", nil
}

// hover computes hover information at the given range. When hover over a single
// point, the input range's start and end are the same.
//
// If we do not support hovering at the position, it returns _, nil, nil:
// an error is only returned if the position is valid but we fail to compute
// hover information.
//
// TODO(adonovan): strength-reduce file.Handle to protocol.DocumentURI.
func hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) (protocol.Range, *hoverResult, error) {
	// Check for hover inside the builtin file before attempting type checking
	// below. NarrowestPackageForFile may or may not succeed, depending on
	// whether this is a GOROOT view, but even if it does succeed the resulting
	// package will be command-line-arguments package. The user should get a
	// hover for the builtin object, not the object type checked from the
	// builtin.go.
	if snapshot.IsBuiltin(fh.URI()) {
		pgf, err := snapshot.BuiltinFile(ctx)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		start, end, err := pgf.RangePos(rng)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		cur, _ := pgf.Cursor().FindByPos(start, end) // can't fail
		if id, ok := cur.Node().(*ast.Ident); ok {
			rng, err := pgf.NodeRange(id)
			if err != nil {
				return protocol.Range{}, nil, err
			}
			var obj types.Object
			if id.Name == "Error" {
				obj = types.Universe.Lookup("error").Type().Underlying().(*types.Interface).Method(0)
			} else {
				obj = types.Universe.Lookup(id.Name)
			}
			if obj != nil {
				h, err := hoverBuiltin(ctx, snapshot, obj)
				return rng, h, err
			}
		}
		return protocol.Range{}, nil, nil // no object to hover
	}

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return protocol.Range{}, nil, err
	}
	var posRange astutil.Range
	{
		start, end, err := pgf.RangePos(rng)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		posRange = astutil.RangeOf(start, end)
	}

	// Handle hovering over the package name, which does not have an associated
	// object.
	// As with import paths, we allow hovering just after the package name.
	if pgf.File.Name != nil && astutil.NodeContains(pgf.File.Name, posRange) {
		return hoverPackageName(pkg, pgf)
	}

	// Handle hovering over embed directive argument.
	pattern, embedRng := parseEmbedDirective(pgf.Mapper, rng)
	if pattern != "" {
		return hoverEmbed(fh, embedRng, pattern)
	}

	// hoverRange is the range reported to the client (e.g. for highlighting).
	// It may be an expansion around the selected identifier,
	// for instance when hovering over a linkname directive or doc link.
	var hoverRange *protocol.Range
	// Handle linkname directive by overriding what to look for.
	if pkgPath, name, offset := parseLinkname(pgf.Mapper, rng); pkgPath != "" && name != "" {
		// rng covering 2nd linkname argument: pkgPath.name.
		rng, err := pgf.PosRange(pgf.Tok.Pos(offset), pgf.Tok.Pos(offset+len(pkgPath)+len(".")+len(name)))
		if err != nil {
			return protocol.Range{}, nil, fmt.Errorf("range over linkname arg: %w", err)
		}
		hoverRange = &rng

		var pos token.Pos
		// Subtle: updates pkg, which defines the FileSet used to resolve (start, end),
		// which were obtained from pkg.
		pkg, pgf, pos, err = findLinkname(ctx, snapshot, PackagePath(pkgPath), name)
		if err != nil {
			return protocol.Range{}, nil, fmt.Errorf("find linkname: %w", err)
		}
		posRange = astutil.RangeOf(pos, pos) // move the range
	}

	// TODO(hxjiang): Hovering over a doc link like "[foo.Foo]" and a direct
	// call to "foo.Foo" can produce different signatures. The doc link hover is
	// qualified relative to the function's definition file, whereas the direct
	// call hover is qualified relative to the current file where the call occurs.

	// Handle hovering over a doc link
	if obj, rng, err := resolveDocLink(pkg, pgf, posRange); obj != nil {
		// Built-ins have no position.
		if isBuiltin(obj) {
			h, err := hoverBuiltin(ctx, snapshot, obj)
			return rng, h, err
		}

		// Find position in declaring file.
		hoverRange = &rng

		var pos token.Pos
		// Subtle: updates pkg, which defines the FileSet used to resolve (start, end),
		// which were obtained from pkg.
		pkg, pgf, pos, err = NarrowestDeclaringPackage(ctx, snapshot, pkg, obj)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		posRange = astutil.RangeOf(pos, pos)
	}

	// Find cursor for selection.
	cur, ok := pgf.Cursor().FindByPos(posRange.Pos(), posRange.End())
	if !ok {
		return protocol.Range{}, nil, fmt.Errorf("hover position not within file")
	}

	// Handle hovering over import specs,
	// which may not have an associated identifier.
	for _, spec := range pgf.File.Imports {
		if astutil.NodeContains(spec, posRange) {
			path := metadata.UnquoteImportPath(spec)
			hoverRes, err := hoverPackageRef(ctx, snapshot, pkg, path)
			if err != nil {
				return protocol.Range{}, nil, err
			}
			rng, err := pgf.NodeRange(spec.Path)
			if err != nil {
				return protocol.Range{}, nil, err
			}
			if hoverRange == nil { // (may have already been set by a doc link)
				hoverRange = &rng
			}
			return *hoverRange, hoverRes, nil // (hoverRes may be nil)
		}
	}

	// By convention, we qualify hover information relative to the package
	// from which the request originated.
	qual := typesinternal.FileQualifier(pgf.File, pkg.Types())

	// Handle hovering over various special kinds of syntax node.
	switch node := cur.Node().(type) {
	// (import paths were handled above)
	case *ast.ReturnStmt:
		return hoverReturnStatement(pgf, cur)
	case *ast.Ident:
		// fall through to rest of function
	case ast.Expr:
		tv, ok := pkg.TypesInfo().Types[node]
		if !ok {
			return protocol.Range{}, nil, nil
		}
		if tv.Value != nil {
			// non-identifier constant expression
			return hoverConstantExpr(pgf, node, tv, posRange)
		}
		// non-constant, non-identifier expression
		// TODO(hxjiang): what info should we provide other than type of
		// the selected expression.
		// TODO(hxjiang): show method set of the given expression' type.
		r := &hoverResult{
			Synopsis:          goastutil.NodeDescription(node),
			FullDocumentation: types.TypeString(pkg.TypesInfo().TypeOf(node), qual),
		}

		highlight, err := pgf.NodeRange(node)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		return highlight, r, nil
	}

	// Handle hover over identifier.

	// The general case: compute hover information for the object referenced by
	// the identifier at (or near) pos.
	objects, err := objectsAt(pkg.TypesInfo(), cur)
	if err != nil {
		return protocol.Range{}, nil, nil // no object to hover
	}
	// Pick first object arbitrarily.
	// Update cursor to its identifier (perhaps nearby).
	obj, cur := objects[0].obj, objects[0].cur
	ident, ok := cur.Node().(*ast.Ident)
	if !ok {
		return protocol.Range{}, nil, nil // e.g. ImportSpec?
	}

	// Unless otherwise specified, rng covers the ident being hovered.
	if hoverRange == nil {
		rng, err := pgf.NodeRange(ident)
		if err != nil {
			return protocol.Range{}, nil, err
		}
		hoverRange = &rng
	}

	// Handle type switch identifiers as a special case,
	// since they don't have a regular object.
	// There's not much useful information to provide.
	if _, selectedType := typeSwitchVars(pkg.TypesInfo(), cur); selectedType != nil {
		v := types.NewVar(obj.Pos(), obj.Pkg(), obj.Name(), selectedType)
		typesinternal.SetVarKind(v, typesinternal.LocalVar)
		signature := types.ObjectString(v, qual)
		return *hoverRange, &hoverResult{
			Signature:  signature,
			SingleLine: signature,
			SymbolName: v.Name(),
		}, nil
	}

	if isBuiltin(obj) {
		// Built-ins have no position.
		h, err := hoverBuiltin(ctx, snapshot, obj)
		return *hoverRange, h, err
	}

	// For all other objects, load type information for their declaring package
	// in order to correctly compute their documentation, signature, and link.
	//
	// Beware: positions derived from decl{Obj,Pkg,PGF,Pos} should be resolve
	// using declPkg.FileSet; other positions should use pkg.FileSet().
	declPkg, declPGF, declPos, err := NarrowestDeclaringPackage(ctx, snapshot, pkg, obj)
	if err != nil {
		return protocol.Range{}, nil, err
	}

	decl, spec, field := findDeclInfo([]*ast.File{declPGF.File}, declPos) // may be nil^3

	var docText string
	if docComment := chooseDocComment(decl, spec, field); docComment != nil {
		docBuf := new(strings.Builder)
		docBuf.WriteString(docComment.Text())

		// docLinks maps the literal text of a doc link to its definition URI.
		// Since the link parser yields progressively for each part of a symbol
		// path (e.g., "fmt", then "fmt.Scanner"), we intentionally overwrite the
		// map entry to ensure the final value is the URI for the complete symbol.
		docLinks := make(map[string]string)
		for docLink := range commentDocLinks(docComment) {
			obj := lookupDocLinkSymbol(declPkg, declPGF, docLink.nameText)
			if obj == nil {
				continue
			}

			// The URI is set to the location of the right-most element in a doc link
			// (e.g., 'Scan' in [fmt.Scanner.Scan]). The sequential yielding of path
			// segments intentionally overwrites the location for previous segments,
			// ensuring only the most specific definition's location is retained.
			loc, err := ObjectLocation(ctx, declPkg.FileSet(), snapshot, obj)
			if err != nil {
				return protocol.Range{}, nil, err
			}

			// The #line,col URL fragment is a non-standard format for file
			// URIs that is supported by VS Code for navigating from hover
			// text. The line and column are 1-based, and the column is a
			// UTF-16 code unit offset, matching the LSP's definition of
			// character position.
			docLinks[docLink.bracketText] = fmt.Sprintf("%s#%d,%d", loc.URI, loc.Range.Start.Line+1, loc.Range.Start.Character+1)
		}

		// Attaching doc links to the bottom of the comment. The non-deterministic
		// order is acceptable as these will be removed later by the [formatHover].
		if len(docLinks) > 0 {
			docBuf.WriteString("\n")
			for doc, link := range docLinks {
				fmt.Fprintf(docBuf, "%s: %s\n", doc, link)
			}
		}

		docText = docBuf.String()
	}

	// By default, types.ObjectString provides a reasonable signature.
	signature := objectString(obj, qual, declPos, declPGF.Tok, spec)

	// When hovering over a reference to a promoted struct field,
	// show the implicitly selected intervening fields.
	if obj, ok := obj.(*types.Var); ok && obj.IsField() {
		if selExpr, ok := cur.Parent().Node().(*ast.SelectorExpr); ok {
			sel, ok := pkg.TypesInfo().Selections[selExpr]
			if ok && len(sel.Index()) > 1 {
				var buf bytes.Buffer
				buf.WriteString(" // through ")
				t := typesinternal.Unpointer(sel.Recv())
				for i, index := range sel.Index()[:len(sel.Index())-1] {
					if i > 0 {
						buf.WriteString(", ")
					}
					field := typesinternal.Unpointer(t.Underlying()).(*types.Struct).Field(index)
					t = field.Type()
					// Inv: fieldType is N or *N for some NamedOrAlias type N.
					if ptr, ok := t.(*types.Pointer); ok {
						buf.WriteString("*")
						t = ptr.Elem()
					}
					// Be defensive in case of ill-typed code:
					if named, ok := t.(typesinternal.NamedOrAlias); ok {
						buf.WriteString(named.Obj().Name())
					}
				}
				// Update signature to include embedded struct info.
				signature += buf.String()
			}
		}
	}

	singleLineSignature := signature

	// Display struct tag for struct fields at the end of the signature.
	if field != nil && field.Tag != nil {
		signature += " " + field.Tag.Value
	}

	// TODO(rfindley): we could do much better for inferred signatures.
	// TODO(adonovan): fuse the two calls below.
	if inferred := inferredSignature(pkg.TypesInfo(), ident); inferred != nil {
		if s := inferredSignatureString(obj, qual, inferred); s != "" {
			signature = s
		}
	}

	// Compute size information for types,
	// including allocator size class,
	// and (size, offset) for struct fields.
	//
	// Also, if a struct type's field ordering is significantly
	// wasteful of space, report its optimal size.
	//
	// This information is useful when debugging crashes or
	// optimizing layout. To reduce distraction, we show it only
	// when hovering over the declaring identifier,
	// but not referring identifiers.
	//
	// Size and alignment vary across OS/ARCH.
	// Gopls will select the appropriate build configuration when
	// viewing a type declaration in a build-tagged file, but will
	// use the default build config for all other types, even
	// if they embed platform-variant types.
	//
	var sizeOffset string

	if ident.Pos() == obj.Pos() {
		// This is the declaring identifier.

		// format returns the decimal and hex representation of x.
		format := func(x int64) string {
			if x < 10 {
				return fmt.Sprintf("%d", x)
			}
			return fmt.Sprintf("%[1]d (%#[1]x)", x)
		}

		// Build string of form "size=... (X% wasted), class=..., offset=...".
		size, wasted, offset := computeSizeOffsetInfo(pkg, cur, obj)
		var buf strings.Builder
		if size >= 0 {
			fmt.Fprintf(&buf, "size=%s", format(size))
			if wasted >= 20 { // >=20% wasted
				fmt.Fprintf(&buf, " (%d%% wasted)", wasted)
			}

			// Include allocator size class, if larger.
			if class := sizeClass(size); class > size {
				fmt.Fprintf(&buf, ", class=%s", format(class))
			}
		}
		if offset >= 0 {
			if buf.Len() > 0 {
				buf.WriteString(", ")
			}
			fmt.Fprintf(&buf, "offset=%s", format(offset))
		}
		sizeOffset = buf.String()
	}

	var typeDecl, methods, fields string

	// For "objects defined by a type spec", the signature produced by
	// objectString is insufficient:
	//  (1) large structs are formatted poorly, with no newlines
	//  (2) we lose inline comments
	// Furthermore, we include a summary of their method set.
	_, isTypeName := obj.(*types.TypeName)
	_, isTypeParam := types.Unalias(obj.Type()).(*types.TypeParam)
	if isTypeName && !isTypeParam {
		var spec1 *ast.TypeSpec
		typeDecl, spec1, err = typeDeclContent(declPGF, declPos, obj.Name())
		if err != nil {
			return protocol.Range{}, nil, err
		}

		// Splice in size/offset at end of first line.
		//   "type T struct { // size=..."
		if sizeOffset != "" {
			nl := strings.IndexByte(typeDecl, '\n')
			if nl < 0 {
				nl = len(typeDecl)
			}
			typeDecl = typeDecl[:nl] + " // " + sizeOffset + typeDecl[nl:]
		}

		// Promoted fields
		//
		// Show a table of accessible fields of the (struct)
		// type that may not be visible in the syntax (above)
		// due to promotion through embedded fields.
		//
		// Example:
		//
		//	// Embedded fields:
		//	foo int	   // through x.y
		//	z   string // through x.y
		if prom := promotedFields(obj.Type(), pkg.Types()); len(prom) > 0 {
			var b strings.Builder
			b.WriteString("// Embedded fields:\n")
			w := tabwriter.NewWriter(&b, 0, 8, 1, ' ', 0)
			for _, f := range prom {
				fmt.Fprintf(w, "%s\t%s\t// through %s\t\n",
					f.field.Name(),
					types.TypeString(f.field.Type(), qual),
					f.path)
			}
			w.Flush() // ignore error
			b.WriteByte('\n')
			fields = b.String()
		}

		// -- methods --

		// For an interface type, explicit methods will have
		// already been displayed when the node was formatted
		// above. Don't list these again.
		var skip map[string]bool
		if iface, ok := spec1.Type.(*ast.InterfaceType); ok {
			if iface.Methods.List != nil {
				for _, m := range iface.Methods.List {
					if len(m.Names) == 1 {
						if skip == nil {
							skip = make(map[string]bool)
						}
						skip[m.Names[0].Name] = true
					}
				}
			}
		}

		// Display all the type's accessible methods,
		// including those that require a pointer receiver,
		// and those promoted from embedded struct fields or
		// embedded interfaces.
		var b strings.Builder
		for _, m := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
			if !accessibleTo(m.Obj(), pkg.Types()) {
				continue // inaccessible
			}
			if skip[m.Obj().Name()] {
				continue // redundant with format.Node above
			}
			if b.Len() > 0 {
				b.WriteByte('\n')
			}

			// Use objectString for its prettier rendering of method receivers.
			b.WriteString(objectString(m.Obj(), qual, token.NoPos, nil, nil))
		}
		methods = b.String()

		signature = typeDecl + "\n" + methods
	} else {
		// Non-types
		if sizeOffset != "" {
			signature += " // " + sizeOffset
		}
	}

	if isTypeName {
		// get the real type decl only if current object is a type,
		// for non-types, we'd better hide the real type decl to avoid possible confusion.
		//
		// realTypeDecl is defined to store the underlying definition of an alias.
		realTypeDecl, _ := findRhsTypeDecl(ctx, snapshot, pkg, obj) // tolerate the error
		if realTypeDecl != "" {
			typeDecl += fmt.Sprintf("\n\n%s", realTypeDecl)
		}
	}

	// Compute link data (on pkg.go.dev or other documentation host).
	//
	// If linkPath is empty, the symbol is not linkable.
	var (
		linkName string            // => link title, always non-empty
		linkPath string            // => link path
		anchor   string            // link anchor
		linkMeta *metadata.Package // metadata for the linked package
	)
	{
		linkMeta = findFileInDeps(snapshot, pkg.Metadata(), declPGF.URI)
		if linkMeta == nil {
			return protocol.Range{}, nil, bug.Errorf("no package data for %s", declPGF.URI)
		}

		// For package names, we simply link to their imported package.
		if pkgName, ok := obj.(*types.PkgName); ok {
			linkName = pkgName.Name()
			linkPath = pkgName.Imported().Path()
			impID := linkMeta.DepsByPkgPath[PackagePath(pkgName.Imported().Path())]
			linkMeta = snapshot.Metadata(impID)
			if linkMeta == nil {
				// Broken imports have fake package paths, so it is not a bug if we
				// don't have metadata. As of writing, there is no way to distinguish
				// broken imports from a true bug where expected metadata is missing.
				return protocol.Range{}, nil, fmt.Errorf("no package data for %s", declPGF.URI)
			}
		} else {
			// For all others, check whether the object is in the package scope, or
			// an exported field or method of an object in the package scope.
			//
			// We try to match pkgsite's heuristics for what is linkable, and what is
			// not.
			var recv types.Object
			switch obj := obj.(type) {
			case *types.Func:
				sig := obj.Signature()
				if sig.Recv() != nil {
					tnames := typeToObjects(sig.Recv().Type())
					if len(tnames) == 1 { // beware empty slice
						recv = tnames[0]
					}
				}
			case *types.Var:
				if obj.IsField() {
					if spec, ok := spec.(*ast.TypeSpec); ok {
						typeName := spec.Name
						scopeObj, _ := obj.Pkg().Scope().Lookup(typeName.Name).(*types.TypeName)
						if scopeObj != nil {
							if st, _ := scopeObj.Type().Underlying().(*types.Struct); st != nil {
								for field := range st.Fields() {
									if obj == field {
										recv = scopeObj
									}
								}
							}
						}
					}
				}
			}

			// Even if the object is not available in package documentation, it may
			// be embedded in a documented receiver. Detect this by searching
			// enclosing selector expressions.
			//
			// TODO(rfindley): pkgsite doesn't document fields from embedding, just
			// methods.
			if recv == nil || !recv.Exported() {
				if enclosing := searchForEnclosing(pkg.TypesInfo(), cur); enclosing != nil {
					recv = enclosing
				} else {
					recv = nil // note: just recv = ... could result in a typed nil.
				}
			}

			pkg := obj.Pkg()
			if recv != nil {
				linkName = fmt.Sprintf("(%s.%s).%s", pkg.Name(), recv.Name(), obj.Name())
				if obj.Exported() && recv.Exported() && typesinternal.IsPackageLevel(recv) {
					linkPath = pkg.Path()
					anchor = fmt.Sprintf("%s.%s", recv.Name(), obj.Name())
				}
			} else {
				linkName = fmt.Sprintf("%s.%s", pkg.Name(), obj.Name())
				if obj.Exported() && typesinternal.IsPackageLevel(obj) {
					linkPath = pkg.Path()
					anchor = obj.Name()
				}
			}
		}
	}

	if snapshot.IsGoPrivatePath(linkPath) || linkMeta.ForTest != "" {
		linkPath = ""
	} else if linkMeta.Module != nil && linkMeta.Module.Version != "" {
		mod := linkMeta.Module
		linkPath = strings.Replace(linkPath, mod.Path, cache.ResolvedString(mod), 1)
	}

	// Handle hover over an imported package name identifier.
	if pkgName, ok := obj.(*types.PkgName); ok {
		hoverRes, err := hoverPackageRef(ctx, snapshot, pkg, metadata.ImportPath(pkgName.Imported().Path()))
		if err != nil {
			return protocol.Range{}, nil, err
		}
		hoverRes.LinkAnchor = anchor
		hoverRes.LinkPath = linkPath
		hoverRes.SymbolName = linkName
		return *hoverRange, hoverRes, nil // (hoverRes may be nil)
	}

	var footer string
	if sym := StdSymbolOf(obj); sym != nil && sym.Version > 0 {
		footer = fmt.Sprintf("Added in %v", sym.Version)
	}

	return *hoverRange, &hoverResult{
		Synopsis:          doc.Synopsis(docText),
		FullDocumentation: docText,
		SingleLine:        singleLineSignature,
		SymbolName:        linkName,
		Signature:         signature,
		LinkPath:          linkPath,
		LinkAnchor:        anchor,
		typeDecl:          typeDecl,
		methods:           methods,
		promotedFields:    fields,
		footer:            footer,
	}, nil
}

// typeDeclContent returns a well formatted type definition.
func typeDeclContent(declPGF *parsego.File, declPos token.Pos, name string) (string, *ast.TypeSpec, error) {
	_, spec, _ := findDeclInfo([]*ast.File{declPGF.File}, declPos) // may be nil^3
	// Don't duplicate comments.
	spec1, ok := spec.(*ast.TypeSpec)
	if !ok {
		// We cannot find a TypeSpec for this type or alias declaration
		// (that is not a type parameter or a built-in).
		// This should be impossible even for ill-formed trees;
		// we suspect that AST repair may be creating inconsistent
		// positions. Don't report a bug in that case. (#64241)
		errorf := fmt.Errorf
		if !declPGF.Fixed() {
			errorf = bug.Errorf
		}
		return "", nil, errorf("type name %q without type spec", name)
	}
	spec2 := *spec1
	spec2.Doc = nil
	spec2.Comment = nil

	var b strings.Builder
	b.WriteString("type ")
	fset := tokeninternal.FileSetFor(declPGF.Tok)
	// TODO(adonovan): use a smarter formatter that omits
	// inaccessible fields (non-exported ones from other packages).
	if err := format.Node(&b, fset, &spec2); err != nil {
		return "", nil, err
	}
	typeDecl := b.String()
	return typeDecl, spec1, nil
}

// hoverBuiltin computes hover information when hovering over a builtin
// identifier.
func hoverBuiltin(ctx context.Context, snapshot *cache.Snapshot, obj types.Object) (*hoverResult, error) {
	// Special handling for error.Error, which is the only builtin method.
	//
	// TODO(rfindley): can this be unified with the handling below?
	if obj.Name() == "Error" {
		signature := obj.String()
		return &hoverResult{
			Signature:  signature,
			SingleLine: signature,
			// TODO(rfindley): these are better than the current behavior.
			// SymbolName: "(error).Error",
			// LinkPath:   "builtin",
			// LinkAnchor: "error.Error",
		}, nil
	}

	pgf, ident, err := builtinDecl(ctx, snapshot, obj)
	if err != nil {
		return nil, err
	}

	var (
		comment *ast.CommentGroup
		decl    ast.Decl
	)
	curIdent, _ := pgf.Cursor().FindNode(ident) // can't fail
	for cur := range curIdent.Enclosing() {
		switch n := cur.Node().(type) {
		case *ast.GenDecl:
			// Separate documentation and signature.
			comment = n.Doc
			node2 := *n
			node2.Doc = nil
			decl = &node2
		case *ast.FuncDecl:
			// Ditto.
			comment = n.Doc
			node2 := *n
			node2.Doc = nil
			decl = &node2
		}
	}

	signature := formatNodeFile(pgf.Tok, decl)
	// Replace fake types with their common equivalent.
	// TODO(rfindley): we should instead use obj.Type(), which would have the
	// *actual* types of the builtin call.
	signature = replacer.Replace(signature)

	docText := comment.Text()
	return &hoverResult{
		Synopsis:          doc.Synopsis(docText),
		FullDocumentation: docText,
		Signature:         signature,
		SingleLine:        obj.String(),
		SymbolName:        obj.Name(),
		LinkPath:          "builtin",
		LinkAnchor:        obj.Name(),
	}, nil
}

// hoverPackageRef computes hover information for the package of the specified
// path imported by pkg. If we do not have metadata for the hovered import, it
// returns _
func hoverPackageRef(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, importPath metadata.ImportPath) (*hoverResult, error) {
	impID := pkg.Metadata().DepsByImpPath[importPath]
	if impID == "" {
		return nil, fmt.Errorf("no package data for import %q", importPath)
	}
	impMetadata := snapshot.Metadata(impID)
	if impMetadata == nil {
		return nil, bug.Errorf("failed to resolve import ID %q", impID)
	}

	// Find the first file with a package doc comment.
	var comment *ast.CommentGroup
	for _, f := range impMetadata.CompiledGoFiles {
		fh, err := snapshot.ReadFile(ctx, f)
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			continue
		}
		pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			continue
		}
		if pgf.File.Doc != nil {
			comment = pgf.File.Doc
			break
		}
	}

	docText := comment.Text()
	return &hoverResult{
		Signature:         "package " + string(impMetadata.Name),
		Synopsis:          doc.Synopsis(docText),
		FullDocumentation: docText,
	}, nil
}

// hoverPackageName computes hover information for the package name of the file
// pgf in pkg.
func hoverPackageName(pkg *cache.Package, pgf *parsego.File) (protocol.Range, *hoverResult, error) {
	var comment *ast.CommentGroup
	for _, pgf := range pkg.CompiledGoFiles() {
		if pgf.File.Doc != nil {
			comment = pgf.File.Doc
			break
		}
	}
	rng, err := pgf.NodeRange(pgf.File.Name)
	if err != nil {
		return protocol.Range{}, nil, err
	}
	docText := comment.Text()

	// List some package attributes at the bottom of the documentation, if
	// applicable.
	type attr struct{ title, value string }
	var attrs []attr

	if !metadata.IsCommandLineArguments(pkg.Metadata().ID) {
		attrs = append(attrs, attr{"Package path", string(pkg.Metadata().PkgPath)})
	}

	if pkg.Metadata().Module != nil {
		attrs = append(attrs, attr{"Module", pkg.Metadata().Module.Path})
	}

	// Show the effective language version for this package.
	if v := pkg.TypesInfo().FileVersions[pgf.File]; v != "" {
		attr := attr{value: version.Lang(v)}
		if v == pkg.Types().GoVersion() {
			attr.title = "Language version"
		} else {
			attr.title = "Language version (current file)"
		}
		attrs = append(attrs, attr)
	}

	// TODO(rfindley): consider exec'ing go here to compute DefaultGODEBUG, or
	// propose adding GODEBUG info to go/packages.

	var footer strings.Builder
	for i, attr := range attrs {
		if i > 0 {
			footer.WriteString("\n")
		}
		fmt.Fprintf(&footer, " - %s: %s", attr.title, attr.value)
	}

	return rng, &hoverResult{
		Signature:         "package " + string(pkg.Metadata().Name),
		Synopsis:          doc.Synopsis(docText),
		FullDocumentation: docText,
		footer:            footer.String(),
	}, nil
}

// hoverConstantExpr computes information about the value of a constant expression.
//
// The provided start and end positions must be precise. For example, when hovering
// over a string literal, the exact cursor position is used to identify and display
// the value of the rune under the cursor.
func hoverConstantExpr(pgf *parsego.File, expr ast.Expr, tv types.TypeAndValue, posRange astutil.Range) (protocol.Range, *hoverResult, error) {
	var (
		value      string    // if non-empty, a constant value to format in hover
		r          rune      // if non-zero, format a description of this rune in hover
		start, end token.Pos // hover span
	)
	if lit, ok := expr.(*ast.BasicLit); ok {
		switch tv.Value.Kind() {
		case constant.Bool:
			fallthrough
		case constant.Float:
			fallthrough
		case constant.Complex:
			fallthrough
		case constant.Unknown:
			// In most cases, basic literals are uninteresting.
			break
		case constant.Int:
			switch lit.Kind {
			case token.CHAR:
				s, err := strconv.Unquote(lit.Value)
				if err != nil {
					// If the conversion fails, it's because of an invalid syntax, therefore
					// there is no rune to be found.
					return protocol.Range{}, nil, nil
				}
				r, _ = utf8.DecodeRuneInString(s)
				if r == utf8.RuneError {
					return protocol.Range{}, nil, fmt.Errorf("rune error")
				}
				start, end = lit.Pos(), lit.End()
			case token.INT:
				// Short literals (e.g. 99 decimal, 07 octal) are uninteresting.
				if len(lit.Value) < 3 {
					return protocol.Range{}, nil, nil
				}

				v := constant.MakeFromLiteral(lit.Value, lit.Kind, 0)
				if v.Kind() != constant.Int {
					return protocol.Range{}, nil, nil
				}

				switch lit.Value[:2] {
				case "0x", "0X":
					// As a special case, try to recognize hexadecimal literals as runes if
					// they are within the range of valid unicode values.
					if v, ok := constant.Int64Val(v); ok && v > 0 && v <= utf8.MaxRune && utf8.ValidRune(rune(v)) {
						r = rune(v)
					}
					fallthrough
				case "0o", "0O", "0b", "0B":
					// Format the decimal value of non-decimal literals.
					value = v.ExactString()
					start, end = lit.Pos(), lit.End()
				default:
					return protocol.Range{}, nil, nil
				}
			}
		case constant.String:
			index, err := astutil.OffsetInStringLiteral(lit, posRange.Pos())
			if err != nil {
				return protocol.Range{}, nil, err
			}
			// pos is the point in the literal where the current rune starts.
			pos, err := astutil.PosInStringLiteral(lit, index)
			if err != nil {
				return protocol.Range{}, nil, err
			}

			rest, err := pgf.PosText(pos, lit.End())
			if err != nil {
				return protocol.Range{}, nil, err
			}

			// Is the selected character denoted by an escape sequence?
			if bytes.HasPrefix(rest, []byte(`\`)) {
				rr, _, tail, err := strconv.UnquoteChar(string(rest), lit.Value[0])
				if err != nil {
					return protocol.Range{}, nil, err
				}

				rawSize := len(rest) - len(tail)

				start, end = pos, pos+token.Pos(rawSize)
				r = rr
			}
		default:
			panic("unexpected constant.Kind")
		}
	} else {
		// By default, provide value information and the expression's range.
		// It is possible evaluated value will give us the wrong number because
		// type checker will perform error recovery.
		// E.g. expression like '\u22111' + 1 is invalid but type checker
		// will yield the value of `\u2211` + 1.

		// We could be more smart about whether we want to evaluate an
		// [ast.Expr] as a number or as a rune by evaluating the syntax of
		// the expression. e.g. rune + int => rune, rune - int => rune.
		value = tv.Value.String()
		start, end = expr.Pos(), expr.End()
	}

	if value == "" && r == 0 { // nothing to format
		return protocol.Range{}, nil, nil
	}

	rng, err := pgf.PosRange(start, end)
	if err != nil {
		return protocol.Range{}, nil, err
	}

	var b strings.Builder
	if value != "" {
		b.WriteString(value)
	}
	if r != 0 {
		runeName := runenames.Name(r)
		if len(runeName) > 0 && runeName[0] == '<' {
			// Check if the rune looks like an HTML tag. If so, trim the surrounding <>
			// characters to work around https://github.com/microsoft/vscode/issues/124042.
			runeName = strings.TrimRight(runeName[1:], ">")
		}
		if b.Len() > 0 {
			b.WriteString(", ")
		}
		if strconv.IsPrint(r) {
			fmt.Fprintf(&b, "'%c', ", r)
		}
		fmt.Fprintf(&b, "U+%04X, %s", r, runeName)
	}
	hover := b.String()
	return rng, &hoverResult{
		Synopsis:          hover,
		FullDocumentation: hover,
	}, nil
}

func hoverReturnStatement(pgf *parsego.File, curReturn inspector.Cursor) (protocol.Range, *hoverResult, error) {
	var funcType *ast.FuncType
	// Find innermost enclosing function.
	for c := range curReturn.Enclosing((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)) {
		switch n := c.Node().(type) {
		case *ast.FuncLit:
			funcType = n.Type
		case *ast.FuncDecl:
			funcType = n.Type
		}
		if funcType != nil {
			break
		}
	}
	// Inv: funcType != nil because a ReturnStmt is always enclosed by a function.
	if funcType.Results == nil {
		return protocol.Range{}, nil, nil // no result variables
	}
	rng, err := pgf.NodeRange(curReturn.Node())
	if err != nil {
		return protocol.Range{}, nil, err
	}
	// Format the function's result type.
	var buf strings.Builder
	var cfg printer.Config
	fset := token.NewFileSet()
	buf.WriteString("returns (")
	for i, field := range funcType.Results.List {
		if i > 0 {
			buf.WriteString(", ")
		}
		cfg.Fprint(&buf, fset, field.Type) // ignore error
	}
	buf.WriteByte(')')
	return rng, &hoverResult{
		Signature: buf.String(),
	}, nil
}

// hoverEmbed computes hover information for a filepath.Match pattern.
// Assumes that the pattern is relative to the location of fh.
func hoverEmbed(fh file.Handle, rng protocol.Range, pattern string) (protocol.Range, *hoverResult, error) {
	s := &strings.Builder{}

	dir := fh.URI().DirPath()
	var matches []string
	err := filepath.WalkDir(dir, func(abs string, d fs.DirEntry, e error) error {
		if e != nil {
			return e
		}
		rel, err := filepath.Rel(dir, abs)
		if err != nil {
			return err
		}
		ok, err := filepath.Match(pattern, rel)
		if err != nil {
			return err
		}
		if ok && !d.IsDir() {
			matches = append(matches, rel)
		}
		return nil
	})
	if err != nil {
		return protocol.Range{}, nil, err
	}

	for _, m := range matches {
		// TODO: Renders each file as separate markdown paragraphs.
		// If forcing (a single) newline is possible it might be more clear.
		fmt.Fprintf(s, "%s\n\n", m)
	}

	res := &hoverResult{
		Signature:         fmt.Sprintf("Embedding %q", pattern),
		Synopsis:          s.String(),
		FullDocumentation: s.String(),
	}
	return rng, res, nil
}

// inferredSignatureString is a wrapper around the types.ObjectString function
// that adds more information to inferred signatures. It will return an empty string
// if the passed types.Object is not a signature.
func inferredSignatureString(obj types.Object, qual types.Qualifier, inferred *types.Signature) string {
	// If the signature type was inferred, prefer the inferred signature with a
	// comment showing the generic signature.
	if sig, _ := obj.Type().Underlying().(*types.Signature); sig != nil && sig.TypeParams().Len() > 0 && inferred != nil {
		obj2 := types.NewFunc(obj.Pos(), obj.Pkg(), obj.Name(), inferred)
		str := types.ObjectString(obj2, qual)
		// Try to avoid overly long lines.
		if len(str) > 60 {
			str += "\n"
		} else {
			str += " "
		}
		str += "// " + types.TypeString(sig, qual)
		return str
	}
	return ""
}

// objectString is a wrapper around the types.ObjectString function.
// It handles adding more information to the object string.
// If spec is non-nil, it may be used to format additional declaration
// syntax, and file must be the token.File describing its positions.
//
// Precondition: obj is not a built-in function or method.
func objectString(obj types.Object, qual types.Qualifier, declPos token.Pos, file *token.File, spec ast.Spec) string {
	str := types.ObjectString(obj, qual)

	switch obj := obj.(type) {
	case *types.Func:
		// We fork ObjectString to improve its rendering of methods:
		// specifically, we show the receiver name,
		// and replace the period in (T).f by a space (#62190).

		sig := obj.Signature()

		var buf bytes.Buffer
		buf.WriteString("func ")
		if recv := sig.Recv(); recv != nil {
			buf.WriteByte('(')
			if _, ok := recv.Type().(*types.Interface); ok {
				// gcimporter creates abstract methods of
				// named interfaces using the interface type
				// (not the named type) as the receiver.
				// Don't print it in full.
				buf.WriteString("interface")
			} else {
				// Show receiver name (go/types does not).
				name := recv.Name()
				if name != "" && name != "_" {
					buf.WriteString(name)
					buf.WriteString(" ")
				}
				types.WriteType(&buf, recv.Type(), qual)
			}
			buf.WriteByte(')')
			buf.WriteByte(' ') // space (go/types uses a period)
		} else if s := qual(obj.Pkg()); s != "" {
			buf.WriteString(s)
			buf.WriteString(".")
		}
		buf.WriteString(obj.Name())
		types.WriteSignature(&buf, sig, qual)
		str = buf.String()

	case *types.Const:
		// Show value of a constant.
		var (
			declaration = obj.Val().String() // default formatted declaration
			comment     = ""                 // if non-empty, a clarifying comment
		)

		// Try to use the original declaration.
		switch obj.Val().Kind() {
		case constant.String:
			// Usually the original declaration of a string doesn't carry much information.
			// Also strings can be very long. So, just use the constant's value.

		default:
			if spec, _ := spec.(*ast.ValueSpec); spec != nil {
				for i, name := range spec.Names {
					if declPos == name.Pos() {
						if i < len(spec.Values) {
							originalDeclaration := formatNodeFile(file, spec.Values[i])
							if originalDeclaration != declaration {
								comment = declaration
								declaration = originalDeclaration
							}
						}
						break
					}
				}
			}
		}

		// Special formatting cases.
		switch typ := types.Unalias(obj.Type()).(type) {
		case *types.Named:
			// Try to add a formatted duration as an inline comment.
			pkg := typ.Obj().Pkg()
			if pkg.Path() == "time" && typ.Obj().Name() == "Duration" && obj.Val().Kind() == constant.Int {
				if d, ok := constant.Int64Val(obj.Val()); ok {
					comment = time.Duration(d).String()
				}
			}
		}
		if comment == declaration {
			comment = ""
		}

		str += " = " + declaration
		if comment != "" {
			str += " // " + comment
		}
	}
	return str
}

// HoverDocForObject returns the best doc comment for obj (for which
// fset provides file/line information).
//
// TODO(rfindley): there appears to be zero(!) tests for this functionality.
func HoverDocForObject(ctx context.Context, snapshot *cache.Snapshot, fset *token.FileSet, obj types.Object) (*ast.CommentGroup, error) {
	if is[*types.TypeName](obj) && is[*types.TypeParam](obj.Type()) {
		return nil, nil
	}

	pgf, pos, err := parseFull(ctx, snapshot, fset, obj)
	if err != nil {
		return nil, fmt.Errorf("re-parsing: %v", err)
	}

	decl, spec, field := findDeclInfo([]*ast.File{pgf.File}, pos)
	return chooseDocComment(decl, spec, field), nil
}

func chooseDocComment(decl ast.Decl, spec ast.Spec, field *ast.Field) *ast.CommentGroup {
	if field != nil {
		if field.Doc != nil {
			return field.Doc
		}
		if field.Comment != nil {
			return field.Comment
		}
		return nil
	}
	switch decl := decl.(type) {
	case *ast.FuncDecl:
		return decl.Doc
	case *ast.GenDecl:
		switch spec := spec.(type) {
		case *ast.ValueSpec:
			if spec.Doc != nil {
				return spec.Doc
			}
			if decl.Doc != nil {
				return decl.Doc
			}
			return spec.Comment
		case *ast.TypeSpec:
			if spec.Doc != nil {
				return spec.Doc
			}
			if decl.Doc != nil {
				return decl.Doc
			}
			return spec.Comment
		}
	}
	return nil
}

// parseFull fully parses the file containing the declaration of obj
// (for which fset provides file/line information). It returns the
// parsego.File and the position of the declaration within it.
//
// BEWARE: the provided FileSet is used only to interpret the provided
// pos; the resulting File and Pos may belong to the same or a
// different FileSet, such as one synthesized by the parser cache, if
// parse-caching is enabled.
func parseFull(ctx context.Context, snapshot *cache.Snapshot, fset *token.FileSet, obj types.Object) (*parsego.File, token.Pos, error) {
	if isBuiltin(obj) {
		pgf, id, err := builtinDecl(ctx, snapshot, obj)
		if err != nil {
			return nil, 0, err
		}
		return pgf, id.Pos(), err
	}
	pos := obj.Pos()
	f := fset.File(pos)
	if f == nil {
		return nil, 0, bug.Errorf("internal error: no file for position %d", pos)
	}

	uri := protocol.URIFromPath(f.Name())
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return nil, 0, err
	}

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, 0, err
	}

	// Translate pos from original file to new file.
	offset, err := safetoken.Offset(f, pos)
	if err != nil {
		return nil, 0, bug.Errorf("offset out of bounds in %q", uri)
	}
	fullPos, err := safetoken.Pos(pgf.Tok, offset)
	if err != nil {
		return nil, 0, err
	}

	return pgf, fullPos, nil
}

// If pkgURL is non-nil, it should be used to generate doc links.
func formatHover(h *hoverResult, options *settings.Options, pkgURL func(path PackagePath, fragment string) protocol.URI) (string, error) {
	markdown := options.PreferredContentFormat == protocol.Markdown
	maybeFenced := func(s string) string {
		if s != "" && markdown {
			s = fmt.Sprintf("```go\n%s\n```", strings.Trim(s, "\n"))
		}
		return s
	}

	switch options.HoverKind {
	case settings.SingleLine:
		return h.SingleLine, nil

	case settings.NoDocumentation:
		return maybeFenced(h.Signature), nil

	case settings.Structured:
		b, err := json.Marshal(h)
		if err != nil {
			return "", err
		}
		return string(b), nil

	case settings.SynopsisDocumentation, settings.FullDocumentation:
		var sections [][]string // assembled below

		// Signature section.
		//
		// For types, we display TypeDecl and Methods,
		// but not Signature, which is redundant (= TypeDecl + "\n" + Methods).
		// For all other symbols, we display Signature;
		// TypeDecl and Methods are empty.
		// TODO(golang/go#70233): When JSON is no more, we could rationalize this.
		if h.typeDecl != "" {
			sections = append(sections, []string{maybeFenced(h.typeDecl)})
		} else {
			sections = append(sections, []string{maybeFenced(h.Signature)})
		}

		// Doc section.
		var doc string
		switch options.HoverKind {
		case settings.SynopsisDocumentation:
			doc = h.Synopsis
		case settings.FullDocumentation:
			doc = h.FullDocumentation
		}
		if options.PreferredContentFormat == protocol.Markdown {
			doc = DocCommentToMarkdown(doc, options)
		}
		sections = append(sections, []string{
			doc,
			maybeFenced(h.promotedFields),
			maybeFenced(h.methods),
		})

		// Footer section.
		sections = append(sections, []string{
			h.footer,
			formatLink(h, options, pkgURL),
		})

		var b strings.Builder
		newline := func() {
			if options.PreferredContentFormat == protocol.Markdown {
				b.WriteString("\n\n")
			} else {
				b.WriteByte('\n')
			}
		}
		for _, section := range sections {
			start := b.Len()
			for _, part := range section {
				if part == "" {
					continue
				}
				// When markdown is available, insert an hline before the start of
				// the section, if there is content above.
				if markdown && b.Len() == start && start > 0 {
					newline()
					b.WriteString("---")
				}
				if b.Len() > 0 {
					newline()
				}
				b.WriteString(part)
			}
		}
		return b.String(), nil

	default:
		return "", fmt.Errorf("invalid HoverKind: %v", options.HoverKind)
	}
}

// StdSymbolOf returns the std lib symbol information of the given obj.
// It returns nil if the input obj is not an exported standard library symbol.
func StdSymbolOf(obj types.Object) *stdlib.Symbol {
	if !obj.Exported() || obj.Pkg() == nil {
		return nil
	}

	// Symbols that not defined in standard library should return early.
	// TODO(hxjiang): The returned slices is binary searchable.
	symbols := stdlib.PackageSymbols[obj.Pkg().Path()]
	if symbols == nil {
		return nil
	}

	// Handle Function, Type, Const & Var.
	if obj != nil && typesinternal.IsPackageLevel(obj) {
		for _, s := range symbols {
			if s.Kind == stdlib.Method || s.Kind == stdlib.Field {
				continue
			}
			if s.Name == obj.Name() {
				return &s
			}
		}
		return nil
	}

	// Handle Method.
	if fn, _ := obj.(*types.Func); fn != nil {
		isPtr, named := typesinternal.ReceiverNamed(fn.Signature().Recv())
		if named != nil && typesinternal.IsPackageLevel(named.Obj()) {
			for _, s := range symbols {
				if s.Kind != stdlib.Method {
					continue
				}
				ptr, recv, name := s.SplitMethod()
				if ptr == isPtr && recv == named.Obj().Name() && name == fn.Name() {
					return &s
				}
			}
			return nil
		}
	}

	// Handle Field.
	if v, _ := obj.(*types.Var); v != nil && v.IsField() {
		for _, s := range symbols {
			if s.Kind != stdlib.Field {
				continue
			}

			typeName, fieldName := s.SplitField()
			if fieldName != v.Name() {
				continue
			}

			typeObj := obj.Pkg().Scope().Lookup(typeName)
			if typeObj == nil {
				continue
			}

			if fieldObj, _, _ := types.LookupFieldOrMethod(typeObj.Type(), true, obj.Pkg(), fieldName); obj == fieldObj {
				return &s
			}
		}
		return nil
	}

	return nil
}

// If pkgURL is non-nil, it should be used to generate doc links.
func formatLink(h *hoverResult, options *settings.Options, pkgURL func(path PackagePath, fragment string) protocol.URI) string {
	if options.LinksInHover == settings.LinksInHover_None || h.LinkPath == "" {
		return ""
	}
	var url protocol.URI
	var caption string
	if pkgURL != nil { // LinksInHover == "gopls"
		// Discard optional module version portion.
		// (Ideally the hoverResult would retain the structure...)
		path := h.LinkPath
		if module, versionDir, ok := strings.Cut(h.LinkPath, "@"); ok {
			// "module@version/dir"
			path = module
			if _, dir, ok := strings.Cut(versionDir, "/"); ok {
				path += "/" + dir
			}
		}
		url = pkgURL(PackagePath(path), h.LinkAnchor)
		caption = "in gopls doc viewer"
	} else {
		if options.LinkTarget == "" {
			return ""
		}
		url = cache.BuildLink(options.LinkTarget, h.LinkPath, h.LinkAnchor)
		caption = "on " + options.LinkTarget
	}
	switch options.PreferredContentFormat {
	case protocol.Markdown:
		return fmt.Sprintf("[`%s` %s](%s)", h.SymbolName, caption, url)
	case protocol.PlainText:
		return ""
	default:
		return url
	}
}

// findDeclInfo returns the syntax nodes involved in the declaration of the
// types.Object with position pos, searching the given list of file syntax
// trees.
//
// Pos may be the position of the name-defining identifier in a FuncDecl,
// ValueSpec, TypeSpec, Field, or as a special case the position of
// Ellipsis.Elt in an ellipsis field.
//
// If found, the resulting decl, spec, and field will be the inner-most
// instance of each node type surrounding pos.
//
// If field is non-nil, pos is the position of a field Var. If field is nil and
// spec is non-nil, pos is the position of a Var, Const, or TypeName object. If
// both field and spec are nil and decl is non-nil, pos is the position of a
// Func object.
//
// It returns a nil decl if no object-defining node is found at pos.
//
// TODO(rfindley): this function has tricky semantics, and may be worth unit
// testing and/or refactoring.
func findDeclInfo(files []*ast.File, pos token.Pos) (decl ast.Decl, spec ast.Spec, field *ast.Field) {
	found := false

	// Visit the files in search of the node at pos.
	stack := make([]ast.Node, 0, 20)

	// Allocate the closure once, outside the loop.
	f := func(n ast.Node, stack []ast.Node) bool {
		if found {
			return false
		}

		// Skip subtrees (incl. files) that don't contain the search point.
		if !(n.Pos() <= pos && pos < n.End()) {
			return false
		}

		switch n := n.(type) {
		case *ast.Field:
			findEnclosingDeclAndSpec := func() {
				for i := len(stack) - 1; i >= 0; i-- {
					switch n := stack[i].(type) {
					case ast.Spec:
						spec = n
					case ast.Decl:
						decl = n
						return
					}
				}
			}

			// Check each field name since you can have
			// multiple names for the same type expression.
			for _, id := range n.Names {
				if id.Pos() == pos {
					field = n
					findEnclosingDeclAndSpec()
					found = true
					return false
				}
			}

			// Check *ast.Field itself. This handles embedded
			// fields which have no associated *ast.Ident name.
			if n.Pos() == pos {
				field = n
				findEnclosingDeclAndSpec()
				found = true
				return false
			}

			// Also check "X" in "...X". This makes it easy to format variadic
			// signature params properly.
			//
			// TODO(rfindley): I don't understand this comment. How does finding the
			// field in this case make it easier to format variadic signature params?
			if ell, ok := n.Type.(*ast.Ellipsis); ok && ell.Elt != nil && ell.Elt.Pos() == pos {
				field = n
				findEnclosingDeclAndSpec()
				found = true
				return false
			}

		case *ast.FuncDecl:
			if n.Name.Pos() == pos {
				decl = n
				found = true
				return false
			}

		case *ast.GenDecl:
			for _, s := range n.Specs {
				switch s := s.(type) {
				case *ast.TypeSpec:
					if s.Name.Pos() == pos {
						decl = n
						spec = s
						found = true
						return false
					}
				case *ast.ValueSpec:
					for _, id := range s.Names {
						if id.Pos() == pos {
							decl = n
							spec = s
							found = true
							return false
						}
					}
				}
			}
		}
		return true
	}
	for _, file := range files {
		ast.PreorderStack(file, stack, f)
		if found {
			return decl, spec, field
		}
	}

	return nil, nil, nil
}

type promotedField struct {
	path  string // path (e.g. "x.y" through embedded fields)
	field *types.Var
}

// promotedFields returns the list of accessible promoted fields of a struct type t.
// (Logic plundered from x/tools/cmd/guru/describe.go.)
func promotedFields(t types.Type, from *types.Package) []promotedField {
	wantField := func(f *types.Var) bool {
		if !accessibleTo(f, from) {
			return false
		}
		// Check that the field is not shadowed.
		obj, _, _ := types.LookupFieldOrMethod(t, true, f.Pkg(), f.Name())
		return obj == f
	}

	var fields []promotedField
	var visit func(t types.Type, stack []*types.Named)
	visit = func(t types.Type, stack []*types.Named) {
		tStruct, ok := typesinternal.Unpointer(t).Underlying().(*types.Struct)
		if !ok {
			return
		}
	fieldloop:
		for f := range tStruct.Fields() {

			// Handle recursion through anonymous fields.
			if f.Anonymous() {
				if _, named := typesinternal.ReceiverNamed(f); named != nil {
					// If we've already visited this named type
					// on this path, break the cycle.
					for _, x := range stack {
						if x.Origin() == named.Origin() {
							continue fieldloop
						}
					}
					visit(f.Type(), append(stack, named))
				}
			}

			// Save accessible promoted fields.
			if len(stack) > 0 && wantField(f) {
				var path strings.Builder
				for i, t := range stack {
					if i > 0 {
						path.WriteByte('.')
					}
					path.WriteString(t.Obj().Name())
				}
				fields = append(fields, promotedField{
					path:  path.String(),
					field: f,
				})
			}
		}
	}
	visit(t, nil)

	return fields
}

func accessibleTo(obj types.Object, pkg *types.Package) bool {
	return obj.Exported() || obj.Pkg() == pkg
}

// computeSizeOffsetInfo reports the size of obj (if a type or struct
// field), its wasted space percentage (if a struct type), and its
// offset (if a struct field). curIdent is obj's declaring identifier.
// It returns -1 for undefined components.
func computeSizeOffsetInfo(pkg *cache.Package, curIdent inspector.Cursor, obj types.Object) (size, wasted, offset int64) {
	size, wasted, offset = -1, -1, -1

	var free typeparams.Free
	sizes := pkg.TypesSizes()

	// size (types and fields)
	if v, ok := obj.(*types.Var); ok && v.IsField() || is[*types.TypeName](obj) {
		// If the field's type has free type parameters,
		// its size cannot be computed.
		if !free.Has(obj.Type()) {
			size = sizes.Sizeof(obj.Type())
		}

		// wasted space (struct types)
		if tStruct, ok := obj.Type().Underlying().(*types.Struct); ok && is[*types.TypeName](obj) && size > 0 {
			fields := slices.Collect(tStruct.Fields())
			if len(fields) > 0 {
				// Sort into descending (most compact) order
				// and recompute size of entire struct.
				sort.Slice(fields, func(i, j int) bool {
					return sizes.Sizeof(fields[i].Type()) >
						sizes.Sizeof(fields[j].Type())
				})
				offsets := sizes.Offsetsof(fields)
				compactSize := offsets[len(offsets)-1] + sizes.Sizeof(fields[len(fields)-1].Type())
				wasted = 100 * (size - compactSize) / size
			}
		}
	}

	// offset (fields)
	if v, ok := obj.(*types.Var); ok && v.IsField() {
		// Find enclosing struct type.
		var tStruct *types.Struct
		if n, _ := cursorutil.FirstEnclosing[*ast.StructType](curIdent); n != nil {
			t, ok := pkg.TypesInfo().TypeOf(n).(*types.Struct)
			if ok {
				// golang/go#69150: TypeOf(n) was observed not to be a Struct (likely
				// nil) in some cases.
				tStruct = t
			}
		}
		if tStruct != nil {
			var fields []*types.Var
			for f := range tStruct.Fields() {
				// If any preceding field's type has free type parameters,
				// its offset cannot be computed.
				if free.Has(f.Type()) {
					break
				}
				fields = append(fields, f)
				if f == v {
					offsets := sizes.Offsetsof(fields)
					offset = offsets[len(offsets)-1]
					break
				}
			}
		}
	}

	return
}

// sizeClass reports the size class for a struct of the specified size, or -1 if unknown.f
// See GOROOT/src/runtime/msize.go for details.
func sizeClass(size int64) int64 {
	if size > 1<<16 {
		return -1 // avoid allocation
	}
	// We assume that bytes.Clone doesn't trim,
	// and reports the underlying size class; see TestSizeClass.
	return int64(cap(bytes.Clone(make([]byte, size))))
}


================================================
FILE: gopls/internal/golang/hover_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import "testing"

func TestSizeClass(t *testing.T) {
	// See GOROOT/src/runtime/msize.go for details.
	for _, test := range [...]struct{ size, class int64 }{
		{8, 8},
		{9, 16},
		{16, 16},
		{17, 24},
	} {
		got := sizeClass(test.size)
		if got != test.class {
			t.Errorf("sizeClass(%d) = %d, want %d", test.size, got, test.class)
		}
	}
}


================================================
FILE: gopls/internal/golang/identifier.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"errors"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/typesinternal"
)

// ErrNoIdentFound is error returned when no identifier is found at a particular position
var ErrNoIdentFound = errors.New("no identifier found")

// inferredSignature determines the resolved non-generic signature for an
// identifier in an instantiation expression.
//
// If no such signature exists, it returns nil.
func inferredSignature(info *types.Info, id *ast.Ident) *types.Signature {
	inst := info.Instances[id]
	sig, _ := types.Unalias(inst.Type).(*types.Signature)
	return sig
}

// searchForEnclosing returns, given the AST path to a SelectorExpr,
// the exported named type of the innermost implicit field selection.
//
// For example, given "new(A).d" where this is (due to embedding) a
// shorthand for "new(A).b.c.d", it returns the named type of c,
// if it is exported, otherwise the type of b, or A.
func searchForEnclosing(info *types.Info, curIdent inspector.Cursor) *types.TypeName {
	selector, _ := cursorutil.FirstEnclosing[*ast.SelectorExpr](curIdent)
	if selector == nil {
		return nil
	}
	sel, ok := info.Selections[selector]
	if !ok {
		return nil
	}
	recv := typesinternal.Unpointer(sel.Recv())

	// Keep track of the last exported type seen.
	var exported *types.TypeName
	if named, ok := types.Unalias(recv).(*types.Named); ok && named.Obj().Exported() {
		exported = named.Obj()
	}
	// We don't want the last element, as that's the field or
	// method itself.
	for _, index := range sel.Index()[:len(sel.Index())-1] {
		if r, ok := recv.Underlying().(*types.Struct); ok {
			recv = typesinternal.Unpointer(r.Field(index).Type())
			if named, ok := types.Unalias(recv).(*types.Named); ok && named.Obj().Exported() {
				exported = named.Obj()
			}
		}
	}
	return exported
}

// typeToObjects returns the underlying type name objects for the given type.
// It unwraps composite types (pointers, slices, etc), and accumulates names
// from each parameter of a function type
func typeToObjects(typ types.Type) []*types.TypeName {
	switch typ := typ.(type) {
	case *types.Alias:
		return []*types.TypeName{typ.Origin().Obj()}
	case *types.Named:
		return []*types.TypeName{typ.Origin().Obj()}
	case *types.Pointer:
		return typeToObjects(typ.Elem())
	case *types.Array:
		return typeToObjects(typ.Elem())
	case *types.Slice:
		return typeToObjects(typ.Elem())
	case *types.Chan:
		return typeToObjects(typ.Elem())
	case *types.Tuple:
		var res []*types.TypeName
		for v := range typ.Variables() {
			res = append(res, typeToObjects(v.Type())...)
		}
		return res
	case *types.Signature:
		return typeToObjects(typ.Results())
	case *types.Basic:
		tname, ok := types.Universe.Lookup(typ.Name()).(*types.TypeName)
		if !ok {
			return nil
		}
		return []*types.TypeName{tname}
	default:
		return nil
	}
}


================================================
FILE: gopls/internal/golang/identifier_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/go/ast/inspector"
)

func TestSearchForEnclosing(t *testing.T) {
	tests := []struct {
		desc string
		// For convenience, consider the first occurrence of the identifier "X" in
		// src.
		src string
		// By convention, "" means no type found.
		wantTypeName string
	}{
		{
			// TODO(rFindley): is this correct, or do we want to resolve I2 here?
			desc:         "embedded interface in interface",
			src:          `package a; var y = i1.X; type i1 interface {I2}; type I2 interface{X()}`,
			wantTypeName: "",
		},
		{
			desc:         "embedded interface in struct",
			src:          `package a; var y = t.X; type t struct {I}; type I interface{X()}`,
			wantTypeName: "I",
		},
		{
			desc:         "double embedding",
			src:          `package a; var y = t1.X; type t1 struct {t2}; type t2 struct {I}; type I interface{X()}`,
			wantTypeName: "I",
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			fset := token.NewFileSet()
			file, err := parser.ParseFile(fset, "a.go", test.src, parser.AllErrors|parser.SkipObjectResolution)
			if err != nil {
				t.Fatal(err)
			}
			var (
				files  = []*ast.File{file}
				column = 1 + bytes.IndexRune([]byte(test.src), 'X')
				pos    = posAt(1, column, fset, "a.go")
			)
			cur, ok := inspector.New(files).Root().FindByPos(pos, pos)
			if !ok {
				t.Fatalf("no ident found at (1, %d)", column)
			}
			info := newInfo()
			if _, err = (*types.Config)(nil).Check("p", fset, files, info); err != nil {
				t.Fatal(err)
			}
			obj := searchForEnclosing(info, cur)
			if obj == nil {
				if test.wantTypeName != "" {
					t.Errorf("searchForEnclosing(...) = <nil>, want %q", test.wantTypeName)
				}
				return
			}
			if got := obj.Name(); got != test.wantTypeName {
				t.Errorf("searchForEnclosing(...) = %q, want %q", got, test.wantTypeName)
			}
		})
	}
}

// posAt returns the token.Pos corresponding to the 1-based (line, column)
// coordinates in the file fname of fset.
func posAt(line, column int, fset *token.FileSet, fname string) token.Pos {
	var tok *token.File
	fset.Iterate(func(tf *token.File) bool {
		if tf.Name() == fname {
			tok = tf
			return false
		}
		return true
	})
	if tok == nil {
		return token.NoPos
	}
	start := tok.LineStart(line)
	return start + token.Pos(column-1)
}

// newInfo returns a types.Info with all maps populated.
func newInfo() *types.Info {
	info := &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		Scopes:       make(map[ast.Node]*types.Scope),
		FileVersions: make(map[*ast.File]string),
	}
	return info
}


================================================
FILE: gopls/internal/golang/implementation.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"iter"
	"reflect"
	"slices"
	"strings"
	"sync"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/methodsets"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/moreiters"
	"golang.org/x/tools/internal/typesinternal"
)

// This file defines the new implementation of the 'implementation'
// operator that does not require type-checker data structures for an
// unbounded number of packages.
//
// TODO(adonovan):
// - Audit to ensure robustness in face of type errors.
// - Eliminate false positives due to 'tricky' cases of the global algorithm.
// - Ensure we have test coverage of:
//      type aliases
//      nil, PkgName, Builtin (all errors)
//      any (empty result)
//      method of unnamed interface type (e.g. var x interface { f() })
//        (the global algorithm may find implementations of this type
//         but will not include it in the index.)

// Implementation returns a new sorted array of locations of
// declarations of types that implement (or are implemented by) the
// type referred to at the given position.
//
// If the position denotes a method, the computation is applied to its
// receiver type and then its corresponding methods are returned.
func Implementation(ctx context.Context, snapshot *cache.Snapshot, f file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	ctx, done := event.Start(ctx, "golang.Implementation")
	defer done()

	locs, err := implementations(ctx, snapshot, f, rng)
	if err != nil {
		return nil, err
	}
	slices.SortFunc(locs, protocol.CompareLocation)
	locs = slices.Compact(locs) // de-duplicate
	return locs, nil
}

func implementations(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	// Type check the current package.
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(start, end) // can't fail

	// Find implementations based on func signatures.
	if locs, err := implFuncs(pkg, cur, start, end); err != errNotHandled {
		return locs, err
	}

	// Find implementations based on method sets.
	var (
		locsMu sync.Mutex
		locs   []protocol.Location
	)
	// relation=0 here means infer direction of the relation
	// (Supertypes/Subtypes) from concreteness of query type/method.
	// (Ideally the implementations request would provide directionality
	// so that one could ask for, say, the superinterfaces of io.ReadCloser;
	// see https://github.com/golang/go/issues/68641#issuecomment-2269293762.)
	const relation = methodsets.TypeRelation(0)
	err = implementationsMsets(ctx, snapshot, pkg, cur, relation, func(_ metadata.PackagePath, _ string, _ bool, loc protocol.Location) {
		locsMu.Lock()
		locs = append(locs, loc)
		locsMu.Unlock()
	})
	return locs, err
}

// An implYieldFunc is a callback called for each match produced by the implementation machinery.
// - name describes the type or method.
// - abstract indicates that the result is an interface type or interface method.
//
// implYieldFunc implementations must be concurrency-safe.
type implYieldFunc func(pkgpath metadata.PackagePath, name string, abstract bool, loc protocol.Location)

// implementationsMsets computes implementations of the type at the
// position specified by cur, by method sets.
//
// rel specifies the desired direction of the relation: Subtype,
// Supertype, or both. As a special case, zero means infer the
// direction from the concreteness of the query object: Supertype for
// a concrete type, Subtype for an interface.
//
// It is shared by Implementations and TypeHierarchy.
func implementationsMsets(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, cur inspector.Cursor, rel methodsets.TypeRelation, yield implYieldFunc) error {
	// First, find the object referenced at the cursor.
	// The object may be declared in a different package.
	obj, err := implementsObj(pkg.TypesInfo(), cur)
	if err != nil {
		return err
	}

	// If the resulting object has a position, we can expand the search to types
	// in the declaring package(s). In this case, we must re-type check these
	// packages in the same realm.
	var (
		declOffset int
		declURI    protocol.DocumentURI
		localPkgs  []*cache.Package
	)
	if obj.Pos().IsValid() { // no local package for error or error.Error
		declPosn := safetoken.StartPosition(pkg.FileSet(), obj.Pos())
		declOffset = declPosn.Offset
		// Type-check the declaring package (incl. variants) for use
		// by the "local" search, which uses type information to
		// enumerate all types within the package that satisfy the
		// query type, even those defined local to a function.
		declURI = protocol.URIFromPath(declPosn.Filename)
		declMPs, err := snapshot.MetadataForFile(ctx, declURI, true)
		if err != nil {
			return err
		}
		if len(declMPs) == 0 {
			return fmt.Errorf("no packages for file %s", declURI)
		}
		ids := make([]PackageID, len(declMPs))
		for i, mp := range declMPs {
			ids[i] = mp.ID
		}
		localPkgs, err = snapshot.TypeCheck(ctx, ids...)
		if err != nil {
			return err
		}
	}

	pkg = nil // no longer used

	// Is the selected identifier a type name or method?
	// (For methods, report the corresponding method names.)
	queryType, queryMethod := typeOrMethod(obj)
	if queryType == nil {
		return bug.Errorf("%s is not a type or method", obj.Name()) // should have been handled by implementsObj
	}

	// Compute the method-set fingerprint used as a key to the global search.
	key, hasMethods := methodsets.KeyOf(queryType)
	if !hasMethods {
		// A type with no methods yields an empty result.
		// (No point reporting that every type satisfies 'any'.)
		return nil
	}

	// If the client specified no relation, infer it
	// from the concreteness of the query type.
	if rel == 0 {
		rel = cond(types.IsInterface(queryType),
			methodsets.Subtype,
			methodsets.Supertype)
	}

	// The global search needs to look at every package in the
	// forward transitive closure of the workspace; see package
	// ./methodsets.
	//
	// For now we do all the type checking before beginning the search.
	// TODO(adonovan): opt: search in parallel topological order
	// so that we can overlap index lookup with typechecking.
	// I suspect a number of algorithms on the result of TypeCheck could
	// be optimized by being applied as soon as each package is available.
	globalMetas, err := snapshot.AllMetadata(ctx)
	if err != nil {
		return err
	}
	metadata.RemoveIntermediateTestVariants(&globalMetas)
	globalIDs := make([]PackageID, 0, len(globalMetas))

	var pkgPath PackagePath
	if obj.Pkg() != nil { // nil for error
		pkgPath = PackagePath(obj.Pkg().Path())
	}
	for _, mp := range globalMetas {
		if mp.PkgPath == pkgPath {
			continue // declaring package is handled by local implementation
		}
		globalIDs = append(globalIDs, mp.ID)
	}
	indexes, err := snapshot.MethodSets(ctx, globalIDs...)
	if err != nil {
		return fmt.Errorf("querying method sets: %v", err)
	}

	// Search local and global packages in parallel.
	var group errgroup.Group

	// local search
	for _, pkg := range localPkgs {
		// The localImplementations algorithm assumes needle and haystack
		// belong to a single package (="realm" of types symbol identities),
		// so we need to recompute obj for each local package.
		// (By contrast the global algorithm is name-based.)
		group.Go(func() error {
			pkgID := pkg.Metadata().ID

			// Find declaring identifier based on (URI, offset)
			// so that localImplementations can locate the
			// corresponding obj/queryType/queryMethod in pkg.
			declFile, err := pkg.File(declURI)
			if err != nil {
				return err // "can't happen"
			}
			pos, err := safetoken.Pos(declFile.Tok, declOffset)
			if err != nil {
				return err // also "can't happen"
			}
			curIdent, ok := declFile.Cursor().FindByPos(pos, pos)
			if !ok {
				return bug.Errorf("position not within file") // can't happen
			}
			id, ok := curIdent.Node().(*ast.Ident)
			if !ok {
				return ErrNoIdentFound // checked earlier
			}
			if err := localImplementations(ctx, snapshot, pkg, id, rel, yield); err != nil {
				return fmt.Errorf("querying local implementations %q: %v", pkgID, err)
			}
			return nil
		})
	}
	// global search
	for _, index := range indexes {
		group.Go(func() error {
			for _, res := range index.Search(key, rel, queryMethod) {
				loc := res.Location
				// Map offsets to protocol.Locations in parallel (may involve I/O).
				group.Go(func() error {
					ploc, err := offsetToLocation(ctx, snapshot, loc.Filename, loc.Start, loc.End)
					if err != nil {
						return err
					}
					yield(index.PkgPath, res.TypeName, res.IsInterface, ploc)
					return nil
				})
			}
			return nil
		})
	}
	return group.Wait()
}

// typeOrMethod returns the type and optional method to use in an
// Implementations operation on the specified symbol.
// It returns a nil type to indicate that the query should not proceed.
//
// (It is factored out to allow it to be used both in the query package
// then (in [localImplementations]) again in the declaring package.)
func typeOrMethod(obj types.Object) (types.Type, *types.Func) {
	switch obj := obj.(type) {
	case *types.TypeName:
		return obj.Type(), nil
	case *types.Func:
		// For methods, use the receiver type, which may be anonymous.
		if recv := obj.Signature().Recv(); recv != nil {
			return recv.Type(), obj
		}
	}
	return nil, nil
}

// offsetToLocation converts an offset-based position to a protocol.Location,
// which requires reading the file.
func offsetToLocation(ctx context.Context, snapshot *cache.Snapshot, filename string, start, end int) (protocol.Location, error) {
	uri := protocol.URIFromPath(filename)
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return protocol.Location{}, err // cancelled, perhaps
	}
	content, err := fh.Content()
	if err != nil {
		return protocol.Location{}, err // nonexistent or deleted ("can't happen")
	}
	m := protocol.NewMapper(uri, content)
	return m.OffsetLocation(start, end)
}

// implementsObj returns the object to query for implementations,
// which is a type name or method.
func implementsObj(info *types.Info, cur inspector.Cursor) (types.Object, error) {
	// This function inherits the limitation of its predecessor in
	// requiring the selection to be an identifier (of a type or
	// method). But there's no fundamental reason why one could
	// not pose this query about any selected piece of syntax that
	// has a type and thus a method set.
	// (If LSP was more thorough about passing text selections as
	// intervals to queries, you could ask about the method set of a
	// subexpression such as x.f().)
	// [Note that this process has begun; see #69058.]
	id, ok := cur.Node().(*ast.Ident)
	if !ok {
		return nil, ErrNoIdentFound
	}

	// Is the object a type or method? Reject other kinds.
	obj := info.Uses[id]
	if obj == nil {
		// Check uses first (unlike ObjectOf) so that T in
		// struct{T} is treated as a reference to a type,
		// not a declaration of a field.
		obj = info.Defs[id]
	}
	switch obj := obj.(type) {
	case *types.TypeName:
		// ok
	case *types.Func:
		if obj.Signature().Recv() == nil {
			return nil, fmt.Errorf("%s is a function, not a method (query at 'func' token to find matching signatures)", id.Name)
		}
	case nil:
		return nil, fmt.Errorf("%s denotes unknown object", id.Name)
	default:
		// e.g. *types.Var -> "var".
		kind := strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
		// TODO(adonovan): improve upon "nil is a nil, not a type".
		return nil, fmt.Errorf("%s is a %s, not a type", id.Name, kind)
	}

	return obj, nil
}

// localImplementations searches within pkg for declarations of all
// supertypes (if rel contains Supertype) or subtypes (if rel contains
// Subtype) of the type or method declared by id within the same
// package, and returns a new unordered array of their locations.
//
// If method is non-nil, the function instead returns the location
// of each type's method (if any) of that ID.
//
// ("Local" refers to the search within the same package, but this
// function's results may include type declarations that are local to
// a function body. The global search index excludes such types
// because reliably naming such types is hard.)
//
// Results are reported via the yield function.
func localImplementations(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, id *ast.Ident, rel methodsets.TypeRelation, yield implYieldFunc) error {
	queryType, queryMethod := typeOrMethod(pkg.TypesInfo().Defs[id])
	if queryType == nil {
		return bug.Errorf("can't find corresponding symbol for %q in package %q", id.Name, pkg)
	}
	queryType = methodsets.EnsurePointer(queryType)

	var msets typeutil.MethodSetCache

	matches := func(candidateType types.Type) bool {
		// Test the direction of the relation.
		// The client may request either direction or both
		// (e.g. when the client is References),
		// and the Result reports each test independently;
		// both tests succeed when comparing identical
		// interface types.
		var got methodsets.TypeRelation
		if rel&methodsets.Supertype != 0 && implements(&msets, queryType, candidateType) {
			got |= methodsets.Supertype
		}
		if rel&methodsets.Subtype != 0 && implements(&msets, candidateType, queryType) {
			got |= methodsets.Subtype
		}
		return got != 0
	}

	// Scan through all type declarations in the syntax.
	for _, pgf := range pkg.CompiledGoFiles() {
		for cur := range pgf.Cursor().Preorder((*ast.TypeSpec)(nil)) {
			spec := cur.Node().(*ast.TypeSpec)
			if spec.Name == id {
				continue // avoid self-comparison of query type
			}
			def := pkg.TypesInfo().Defs[spec.Name]
			if def == nil {
				continue // "can't happen" for types
			}
			if def.(*types.TypeName).IsAlias() {
				continue // skip type aliases to avoid duplicate reporting
			}
			candidateType := methodsets.EnsurePointer(def.Type())
			if !matches(candidateType) {
				continue
			}

			// Ignore types with empty method sets.
			// (No point reporting that every type satisfies 'any'.)
			mset := msets.MethodSet(candidateType)
			if mset.Len() == 0 {
				continue
			}

			isInterface := types.IsInterface(def.Type())

			if queryMethod == nil {
				// Found matching type.
				loc := mustLocation(pgf, spec.Name)
				yield(pkg.Metadata().PkgPath, spec.Name.Name, isInterface, loc)
				continue
			}

			// Find corresponding method.
			//
			// We can't use LookupFieldOrMethod because it requires
			// the methodID's types.Package, which we don't know.
			// We could recursively search pkg.Imports for it,
			// but it's easier to walk the method set.
			for method := range mset.Methods() {
				m := method.Obj()
				if m.Pos() == id.Pos() {
					continue // avoid self-comparison of query method
				}
				if m.Id() == queryMethod.Id() {
					posn := safetoken.StartPosition(pkg.FileSet(), m.Pos())
					loc, err := offsetToLocation(ctx, snapshot, posn.Filename, posn.Offset, posn.Offset+len(m.Name()))
					if err != nil {
						return err
					}
					yield(pkg.Metadata().PkgPath, m.Name(), isInterface, loc)
					break
				}
			}
		}
	}

	// Special case: for types that satisfy error,
	// report error in builtin.go (see #59527).
	//
	// (An inconsistency: we always report the type error
	// even when the query was for the method error.Error.)
	if matches(errorType) {
		loc, err := errorLocation(ctx, snapshot)
		if err != nil {
			return err
		}
		yield("", "error", true, loc)
	}

	return nil
}

var errorType = types.Universe.Lookup("error").Type()

// errorLocation returns the location of the 'error' type in builtin.go.
func errorLocation(ctx context.Context, snapshot *cache.Snapshot) (protocol.Location, error) {
	pgf, err := snapshot.BuiltinFile(ctx)
	if err != nil {
		return protocol.Location{}, err
	}
	for _, decl := range pgf.File.Decls {
		if decl, ok := decl.(*ast.GenDecl); ok {
			for _, spec := range decl.Specs {
				if spec, ok := spec.(*ast.TypeSpec); ok && spec.Name.Name == "error" {
					return pgf.NodeLocation(spec.Name)
				}
			}
		}
	}
	return protocol.Location{}, fmt.Errorf("built-in error type not found")
}

// implements reports whether x implements y.
// If one or both types are generic, the result indicates whether the
// interface may be implemented under some instantiation.
func implements(msets *typeutil.MethodSetCache, x, y types.Type) bool {
	if !types.IsInterface(y) {
		return false
	}

	// For each interface method of y, check that x has it too.
	// It is not necessary to compute x's complete method set.
	//
	// If y is a constraint interface (!y.IsMethodSet()), we
	// ignore non-interface terms, leading to occasional spurious
	// matches. We could in future filter based on them, but it
	// would lead to divergence with the global (fingerprint-based)
	// algorithm, which operates only on methodsets.
	ymset := msets.MethodSet(y)
	for method := range ymset.Methods() {
		ym := method.Obj().(*types.Func)

		xobj, _, _ := types.LookupFieldOrMethod(x, false, ym.Pkg(), ym.Name())
		xm, ok := xobj.(*types.Func)
		if !ok {
			return false // x lacks a method of y
		}
		if !unify(xm.Signature(), ym.Signature(), nil) {
			return false // signatures do not match
		}
	}
	return true // all methods found
}

// unify reports whether the types of x and y match.
//
// If unifier is nil, unify reports only whether it succeeded.
// If unifier is non-nil, it is populated with the values
// of type parameters determined during a successful unification.
// If unification succeeds without binding a type parameter, that parameter
// will not be present in the map.
//
// On entry, the unifier's contents are treated as the values of already-bound type
// parameters, constraining the unification.
//
// For example, if unifier is an empty (not nil) map on entry, then the types
//
//	func[T any](T, int)
//
// and
//
//	func[U any](bool, U)
//
// will unify, with T=bool and U=int.
// That is, the contents of unifier after unify returns will be
//
//	{T: bool, U: int}
//
// where "T" is the type parameter T and "bool" is the basic type for bool.
//
// But if unifier is {T: int} is int on entry, then unification will fail, because T
// does not unify with bool.
//
// Unify does not preserve aliases. For example, given the following:
//
//	type String = string
//	type A[T] = T
//
// unification succeeds with T bound to string, not String.
//
// See also: unify in cache/methodsets/fingerprint, which implements
// unification for type fingerprints, for the global index.
//
// BUG: literal interfaces are not handled properly. But this function is currently
// used only for signatures, where such types are very rare.
func unify(x, y types.Type, unifier map[*types.TypeParam]types.Type) bool {
	// bindings[tp] is the binding for type parameter tp.
	// Although type parameters are nominally bound to types, each bindings[tp]
	// is a pointer to a type, so unbound variables that unify can share a binding.
	bindings := map[*types.TypeParam]*types.Type{}

	// Bindings is initialized with pointers to the provided types.
	for tp, t := range unifier {
		bindings[tp] = &t
	}

	// bindingFor returns the *types.Type in bindings for tp if tp is not nil,
	// creating one if needed.
	bindingFor := func(tp *types.TypeParam) *types.Type {
		if tp == nil {
			return nil
		}
		b := bindings[tp]
		if b == nil {
			b = new(types.Type)
			bindings[tp] = b
		}
		return b
	}

	// bind sets b to t if b does not occur in t.
	bind := func(b *types.Type, t types.Type) bool {
		for tp := range typeParams(t) {
			if b == bindings[tp] {
				return false // failed "occurs" check
			}
		}
		*b = t
		return true
	}

	// uni performs the actual unification.
	depth := 0
	var uni func(x, y types.Type) bool
	uni = func(x, y types.Type) bool {
		// Panic if recursion gets too deep, to detect bugs before
		// overflowing the stack.
		depth++
		defer func() { depth-- }()
		if depth > 100 {
			panic("unify: max depth exceeded")
		}

		x = types.Unalias(x)
		y = types.Unalias(y)

		tpx, _ := x.(*types.TypeParam)
		tpy, _ := y.(*types.TypeParam)
		if tpx != nil || tpy != nil {
			// Identical type params unify.
			if tpx == tpy {
				return true
			}
			bx := bindingFor(tpx)
			by := bindingFor(tpy)

			// If both args are type params and neither is bound, have them share a binding.
			if bx != nil && by != nil && *bx == nil && *by == nil {
				// Arbitrarily give y's binding to x.
				bindings[tpx] = by
				return true
			}
			// Treat param bindings like original args in what follows.
			if bx != nil && *bx != nil {
				x = *bx
			}
			if by != nil && *by != nil {
				y = *by
			}
			// If the x param is unbound, bind it to y.
			if bx != nil && *bx == nil {
				return bind(bx, y)
			}
			// If the y param is unbound, bind it to x.
			if by != nil && *by == nil {
				return bind(by, x)
			}
			// Unify the binding of a bound parameter.
			return uni(x, y)
		}

		// Neither arg is a type param.

		if reflect.TypeOf(x) != reflect.TypeOf(y) {
			return false // mismatched types
		}

		switch x := x.(type) {
		case *types.Array:
			y := y.(*types.Array)
			return x.Len() == y.Len() &&
				uni(x.Elem(), y.Elem())

		case *types.Basic:
			y := y.(*types.Basic)
			return x.Kind() == y.Kind()

		case *types.Chan:
			y := y.(*types.Chan)
			return x.Dir() == y.Dir() &&
				uni(x.Elem(), y.Elem())

		case *types.Interface:
			y := y.(*types.Interface)
			// TODO(adonovan,jba): fix: for correctness, we must check
			// that both interfaces have the same set of methods
			// modulo type parameters, while avoiding the risk of
			// unbounded interface recursion.
			//
			// Since non-empty interface literals are vanishingly
			// rare in methods signatures, we ignore this for now.
			// If more precision is needed we could compare method
			// names and arities, still without full recursion.
			return x.NumMethods() == y.NumMethods()

		case *types.Map:
			y := y.(*types.Map)
			return uni(x.Key(), y.Key()) &&
				uni(x.Elem(), y.Elem())

		case *types.Named:
			y := y.(*types.Named)
			if x.Origin() != y.Origin() {
				return false // different named types
			}
			xtargs := x.TypeArgs()
			ytargs := y.TypeArgs()
			if xtargs.Len() != ytargs.Len() {
				return false // arity error (ill-typed)
			}
			for i := range xtargs.Len() {
				if !uni(xtargs.At(i), ytargs.At(i)) {
					return false // mismatched type args
				}
			}
			return true

		case *types.Pointer:
			y := y.(*types.Pointer)
			return uni(x.Elem(), y.Elem())

		case *types.Signature:
			y := y.(*types.Signature)
			return x.Variadic() == y.Variadic() &&
				uni(x.Params(), y.Params()) &&
				uni(x.Results(), y.Results())

		case *types.Slice:
			y := y.(*types.Slice)
			return uni(x.Elem(), y.Elem())

		case *types.Struct:
			y := y.(*types.Struct)
			if x.NumFields() != y.NumFields() {
				return false
			}
			for i := range x.NumFields() {
				xf := x.Field(i)
				yf := y.Field(i)
				if xf.Embedded() != yf.Embedded() ||
					xf.Name() != yf.Name() ||
					x.Tag(i) != y.Tag(i) ||
					!xf.Exported() && xf.Pkg() != yf.Pkg() ||
					!uni(xf.Type(), yf.Type()) {
					return false
				}
			}
			return true

		case *types.Tuple:
			y := y.(*types.Tuple)
			if x.Len() != y.Len() {
				return false
			}
			for i := range x.Len() {
				if !uni(x.At(i).Type(), y.At(i).Type()) {
					return false
				}
			}
			return true

		default: // incl. *Union, *TypeParam
			panic(fmt.Sprintf("unexpected Type %#v", x))
		}
	}

	if !uni(x, y) {
		clear(unifier)
		return false
	}

	// Populate the input map with the resulting types.
	if unifier != nil {
		for tparam, tptr := range bindings {
			unifier[tparam] = *tptr
		}
	}
	return true
}

// typeParams yields all the free type parameters within t that are relevant for
// unification.
//
// Note: this function is tailored for the specific needs of the unification algorithm.
// Don't try to use it for other purposes, see [typeparams.Free] instead.
func typeParams(t types.Type) iter.Seq[*types.TypeParam] {

	return func(yield func(*types.TypeParam) bool) {
		seen := map[*types.TypeParam]bool{} // yield each type param only once

		// tps(t) yields each TypeParam in t and returns false to stop.
		var tps func(types.Type) bool
		tps = func(t types.Type) bool {
			t = types.Unalias(t)

			switch t := t.(type) {
			case *types.TypeParam:
				if seen[t] {
					return true
				}
				seen[t] = true
				return yield(t)

			case *types.Basic:
				return true

			case *types.Array:
				return tps(t.Elem())

			case *types.Chan:
				return tps(t.Elem())

			case *types.Interface:
				// TODO(jba): implement.
				return true

			case *types.Map:
				return tps(t.Key()) && tps(t.Elem())

			case *types.Named:
				if t.Origin() == t {
					// generic type: look at type params
					return moreiters.Every(t.TypeParams().TypeParams(),
						func(tp *types.TypeParam) bool { return tps(tp) })
				}
				// instantiated type: look at type args
				return moreiters.Every(t.TypeArgs().Types(), tps)

			case *types.Pointer:
				return tps(t.Elem())

			case *types.Signature:
				return tps(t.Params()) && tps(t.Results())

			case *types.Slice:
				return tps(t.Elem())

			case *types.Struct:
				return moreiters.Every(t.Fields(),
					func(v *types.Var) bool { return tps(v.Type()) })

			case *types.Tuple:
				return moreiters.Every(t.Variables(),
					func(v *types.Var) bool { return tps(v.Type()) })

			default: // incl. *Union
				panic(fmt.Sprintf("unexpected Type %#v", t))
			}
		}

		tps(t)
	}
}

var (
	// TODO(adonovan): why do various RPC handlers related to
	// IncomingCalls return (nil, nil) on the protocol in response
	// to this error? That seems like a violation of the protocol.
	// Is it perhaps a workaround for VSCode behavior?
	errNoObjectFound = errors.New("no object found")
)

// --- Implementations based on signature types --

// implFuncs finds Implementations based on func types.
//
// Just as an interface type abstracts a set of concrete methods, a
// function type abstracts a set of concrete functions. Gopls provides
// analogous operations for navigating from abstract to concrete and
// back in the domain of function types.
//
// A single type (for example http.HandlerFunc) can have both an
// underlying type of function (types.Signature) and have methods that
// cause it to implement an interface. To avoid a confusing user
// interface we want to separate the two operations so that the user
// can unambiguously specify the query they want.
//
// So, whereas Implementations queries on interface types are usually
// keyed by an identifier of a named type, Implementations queries on
// function types are keyed by the "func" keyword, or by the "(" of a
// call expression. The query relates two sets of locations:
//
//  1. the "func" token of each function declaration (FuncDecl or
//     FuncLit). These are analogous to declarations of concrete
//     methods.
//
//  2. uses of abstract functions:
//
//     (a) the "func" token of each FuncType that is not part of
//     Func{Decl,Lit}. These are analogous to interface{...} types.
//
//     (b) the "(" paren of each dynamic call on a value of an
//     abstract function type. These are analogous to references to
//     interface method names, but no names are involved, which has
//     historically made them hard to search for.
//
// An Implementations query on a location in set 1 returns set 2,
// and vice versa.
//
// curSel denotes the selected syntax node whose type drives the
// pos indicates the exact cursor position.
//
// implFuncs returns errNotHandled to indicate that we should try the
// regular method-sets algorithm.
func implFuncs(pkg *cache.Package, curSel inspector.Cursor, start, end token.Pos) ([]protocol.Location, error) {
	info := pkg.TypesInfo()
	if info.Types == nil || info.Defs == nil || info.Uses == nil {
		panic("one of info.Types, .Defs or .Uses is nil")
	}

	// Find innermost enclosing FuncType or CallExpr.
	//
	// We are looking for specific tokens (FuncType.Func and
	// CallExpr.Lparen), but FindPos prefers an adjoining
	// subexpression: given f(x) without additional spaces between
	// tokens, FindPos always returns either f or x, never the
	// CallExpr itself. Thus we must ascend the tree.
	//
	// Another subtlety: due to an edge case in go/ast, FindPos at
	// FuncDecl.Type.Func does not return FuncDecl.Type, only the
	// FuncDecl, because the orders of tree positions and tokens
	// are inconsistent. Consequently, the ancestors for a "func"
	// token of Func{Lit,Decl} do not include FuncType, hence the
	// explicit cases below.
	for cur := range curSel.Enclosing(
		(*ast.FuncDecl)(nil),
		(*ast.FuncLit)(nil),
		(*ast.FuncType)(nil),
		(*ast.CallExpr)(nil),
	) {
		switch n := cur.Node().(type) {
		case *ast.FuncDecl, *ast.FuncLit:
			if inToken(n.Pos(), "func", start, end) {
				// Case 1: concrete function declaration.
				// Report uses of corresponding function types.
				switch n := n.(type) {
				case *ast.FuncDecl:
					return funcUses(pkg, info.Defs[n.Name].Type())
				case *ast.FuncLit:
					return funcUses(pkg, info.TypeOf(n.Type))
				}
			}

		case *ast.FuncType:
			if n.Func.IsValid() && inToken(n.Func, "func", start, end) && !beneathFuncDef(cur) {
				// Case 2a: function type.
				// Report declarations of corresponding concrete functions.
				return funcDefs(pkg, info.TypeOf(n))
			}

		case *ast.CallExpr:
			if inToken(n.Lparen, "(", start, end) {
				t := dynamicFuncCallType(info, n)
				if t == nil {
					return nil, fmt.Errorf("not a dynamic function call")
				}
				// Case 2b: dynamic call of function value.
				// Report declarations of corresponding concrete functions.
				return funcDefs(pkg, t)
			}
		}
	}

	// It's probably a query of a named type or method.
	// Fall back to the method-sets computation.
	return nil, errNotHandled
}

var errNotHandled = errors.New("not handled")

// funcUses returns all locations in the workspace that are dynamic
// uses of the specified function type.
func funcUses(pkg *cache.Package, t types.Type) ([]protocol.Location, error) {
	var locs []protocol.Location

	// local search
	for _, pgf := range pkg.CompiledGoFiles() {
		for cur := range pgf.Cursor().Preorder((*ast.CallExpr)(nil), (*ast.FuncType)(nil)) {
			var pos, end token.Pos
			var ftyp types.Type
			switch n := cur.Node().(type) {
			case *ast.CallExpr:
				ftyp = dynamicFuncCallType(pkg.TypesInfo(), n)
				pos, end = n.Lparen, n.Lparen+token.Pos(len("("))

			case *ast.FuncType:
				if !beneathFuncDef(cur) {
					// func type (not def)
					ftyp = pkg.TypesInfo().TypeOf(n)
					pos, end = n.Func, n.Func+token.Pos(len("func"))
				}
			}
			if ftyp == nil {
				continue // missing type information
			}
			if unify(t, ftyp, nil) {
				loc, err := pgf.PosLocation(pos, end)
				if err != nil {
					return nil, err
				}
				locs = append(locs, loc)
			}
		}
	}

	// TODO(adonovan): implement global search

	return locs, nil
}

// funcDefs returns all locations in the workspace that define
// functions of the specified type.
func funcDefs(pkg *cache.Package, t types.Type) ([]protocol.Location, error) {
	var locs []protocol.Location

	// local search
	for _, pgf := range pkg.CompiledGoFiles() {
		for curFn := range pgf.Cursor().Preorder((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)) {
			fn := curFn.Node()
			var ftyp types.Type
			switch fn := fn.(type) {
			case *ast.FuncDecl:
				ftyp = pkg.TypesInfo().Defs[fn.Name].Type()
			case *ast.FuncLit:
				ftyp = pkg.TypesInfo().TypeOf(fn)
			}
			if ftyp == nil {
				continue // missing type information
			}
			if unify(t, ftyp, nil) {
				pos := fn.Pos()
				loc, err := pgf.PosLocation(pos, pos+token.Pos(len("func")))
				if err != nil {
					return nil, err
				}
				locs = append(locs, loc)
			}
		}
	}

	// TODO(adonovan): implement global search, by analogy with
	// methodsets algorithm.
	//
	// One optimization: if any signature type has free package
	// names, look for matches only in packages among the rdeps of
	// those packages.

	return locs, nil
}

// beneathFuncDef reports whether the specified FuncType cursor is a
// child of Func{Decl,Lit}.
func beneathFuncDef(cur inspector.Cursor) bool {
	switch cur.ParentEdgeKind() {
	case edge.FuncDecl_Type, edge.FuncLit_Type:
		return true
	}
	return false
}

// dynamicFuncCallType reports whether call is a dynamic (non-method) function call.
// If so, it returns the function type, otherwise nil.
//
// Tested via ../test/marker/testdata/implementation/signature.txt.
func dynamicFuncCallType(info *types.Info, call *ast.CallExpr) types.Type {
	if typesinternal.ClassifyCall(info, call) == typesinternal.CallDynamic {
		if tv, ok := info.Types[call.Fun]; ok {
			return tv.Type.Underlying()
		}
	}
	return nil
}

// inToken reports whether (start, end) is within the token of
// the specified position and string.
func inToken(tokPos token.Pos, tokStr string, start, end token.Pos) bool {
	return tokPos <= start && end <= tokPos+token.Pos(len(tokStr))
}


================================================
FILE: gopls/internal/golang/implementation_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"go/types"
	"maps"
	"testing"

	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestUnify(t *testing.T) {
	// Most cases from TestMatches in gopls/internal/util/fingerprint/fingerprint_test.go.
	const src = `
-- go.mod --
module example.com
go 1.24

-- a/a.go --
package a

type Int = int
type String = string

// Eq.Equal matches casefold.Equal.
type Eq[T any] interface { Equal(T, T) bool }
type casefold struct{}
func (casefold) Equal(x, y string) bool

// A matches AString.
type A[T any] = struct { x T }
type AString = struct { x string }

func C1[T any](int, T, ...string) T { panic(0) }
func C2[U any](int, int, ...U) bool { panic(0) }
func C3(int, bool, ...string) rune
func C4(int, bool, ...string)
func C5(int, float64, bool, string) bool
func C6(int, bool, ...string) bool

func DAny[T any](Named[T]) { panic(0) }
func DString(Named[string])
func DInt(Named[int])

type Named[T any] struct { x T }

func E1(byte) rune
func E2(uint8) int32
func E3(int8) uint32

// generic vs. generic
func F1[T any](T) { panic(0) }
func F2[T any](*T) { panic(0) }
func F3[T any](T, T) { panic(0) }
func F4[U any](U, *U) {panic(0) }
func F4a[U any](U, Named[U]) {panic(0) }
func F5[T, U any](T, U, U) { panic(0) }
func F6[T any](T, int, T) { panic(0) }
func F7[T any](bool, T, T) { panic(0) }
func F8[V any](*V, int, int) { panic(0) }
func F9[V any](V, *V, V) { panic(0) }
`
	type tmap = map[*types.TypeParam]types.Type

	var (
		boolType   = types.Typ[types.Bool]
		intType    = types.Typ[types.Int]
		stringType = types.Typ[types.String]
	)

	pkg := testfiles.LoadPackages(t, txtar.Parse([]byte(src)), "./a")[0]
	scope := pkg.Types.Scope()

	tparam := func(name string, index int) *types.TypeParam {
		obj := scope.Lookup(name)
		var tps *types.TypeParamList
		switch obj := obj.(type) {
		case *types.Func:
			tps = obj.Signature().TypeParams()
		case *types.TypeName:
			if n, ok := obj.Type().(*types.Named); ok {
				tps = n.TypeParams()
			} else {
				tps = obj.Type().(*types.Alias).TypeParams()
			}
		default:
			t.Fatalf("unsupported object of type %T", obj)
		}
		return tps.At(index)
	}

	for _, test := range []struct {
		x, y       string // the symbols in the above source code whose types to unify
		method     string // optional field or method
		params     tmap   // initial values of type params
		want       bool   // success or failure
		wantParams tmap   // expected output
	}{
		{
			// In Eq[T], T is bound to string.
			x:          "Eq",
			y:          "casefold",
			method:     "Equal",
			want:       true,
			wantParams: tmap{tparam("Eq", 0): stringType},
		},
		{
			// If we unify A[T] and A[string], T should be bound to string.
			x:          "A",
			y:          "AString",
			want:       true,
			wantParams: tmap{tparam("A", 0): stringType},
		},
		{x: "A", y: "Eq", want: false}, // completely unrelated
		{
			// C1's U unifies with C6's bool.
			x:          "C1",
			y:          "C6",
			wantParams: tmap{tparam("C1", 0): boolType},
			want:       true,
		},
		// C1 fails to unify with C2 because C1's T must be bound to both int and bool.
		{x: "C1", y: "C2", want: false},
		// The remaining "C" cases fail for less interesting reasons, usually different numbers
		// or types of parameters or results.
		{x: "C1", y: "C3", want: false},
		{x: "C1", y: "C4", want: false},
		{x: "C1", y: "C5", want: false},
		{x: "C2", y: "C3", want: false},
		{x: "C2", y: "C4", want: false},
		{x: "C3", y: "C4", want: false},
		{
			x:          "DAny",
			y:          "DString",
			want:       true,
			wantParams: tmap{tparam("DAny", 0): stringType},
		},
		{x: "DString", y: "DInt", want: false}, // different instantiations of Named
		{x: "E1", y: "E2", want: true},         // byte and rune are just aliases
		{x: "E2", y: "E3", want: false},

		// The following tests cover all of the type param cases of unify.
		{
			// F1[*int] = F2[int], for example
			// F1's T is bound to a pointer to F2's T.
			x: "F1",
			// F2's T is unbound: any instantiation works.
			y:          "F2",
			want:       true,
			wantParams: tmap{tparam("F1", 0): types.NewPointer(tparam("F2", 0))},
		},
		{x: "F3", y: "F4", want: false},  // would require U identical to *U, prevented by occur check
		{x: "F3", y: "F4a", want: false}, // occur check through Named[T]
		{
			x:    "F5",
			y:    "F6",
			want: true,
			wantParams: tmap{
				tparam("F5", 0): intType,
				tparam("F5", 1): intType,
				tparam("F6", 0): intType,
			},
		},
		{x: "F6", y: "F7", want: false}, // both are bound
		{
			x:      "F5",
			y:      "F6",
			params: tmap{tparam("F6", 0): intType}, // consistent with the result
			want:   true,
			wantParams: tmap{
				tparam("F5", 0): intType,
				tparam("F5", 1): intType,
				tparam("F6", 0): intType,
			},
		},
		{
			x:      "F5",
			y:      "F6",
			params: tmap{tparam("F6", 0): boolType}, // not consistent
			want:   false,
		},
		{x: "F6", y: "F7", want: false}, // both are bound
		{
			// T=*V, U=int, V=int
			x:    "F5",
			y:    "F8",
			want: true,
			wantParams: tmap{
				tparam("F5", 0): types.NewPointer(tparam("F8", 0)),
				tparam("F5", 1): intType,
			},
		},
		{
			// T=*V, U=int, V=int
			// Partial initial information is fine, as long as it's consistent.
			x:      "F5",
			y:      "F8",
			want:   true,
			params: tmap{tparam("F5", 1): intType},
			wantParams: tmap{
				tparam("F5", 0): types.NewPointer(tparam("F8", 0)),
				tparam("F5", 1): intType,
			},
		},
		{
			// T=*V, U=int, V=int
			// Partial initial information is fine, as long as it's consistent.
			x:      "F5",
			y:      "F8",
			want:   true,
			params: tmap{tparam("F5", 0): types.NewPointer(tparam("F8", 0))},
			wantParams: tmap{
				tparam("F5", 0): types.NewPointer(tparam("F8", 0)),
				tparam("F5", 1): intType,
			},
		},
		{x: "F5", y: "F9", want: false}, // T is unbound, V is bound, and T occurs in V
		{
			// T bound to Named[T']
			x:    "F1",
			y:    "DAny",
			want: true,
			wantParams: tmap{
				tparam("F1", 0): scope.Lookup("DAny").(*types.Func).Signature().Params().At(0).Type()},
		},
	} {

		lookup := func(name string) types.Type {
			obj := scope.Lookup(name)
			if obj == nil {
				t.Fatalf("Lookup %s failed", name)
			}
			if test.method != "" {
				obj, _, _ = types.LookupFieldOrMethod(obj.Type(), true, pkg.Types, test.method)
				if obj == nil {
					t.Fatalf("Lookup %s.%s failed", name, test.method)
				}
			}
			return obj.Type()
		}

		check := func(a, b string, want, compareParams bool) {
			t.Helper()

			ta := lookup(a)
			tb := lookup(b)

			var gotParams tmap
			if test.params == nil {
				// Get the unifier even if there are no input params.
				gotParams = tmap{}
			} else {
				gotParams = maps.Clone(test.params)
			}
			got := unify(ta, tb, gotParams)
			if got != want {
				t.Errorf("a=%s b=%s method=%s: unify returned %t for these inputs:\n- %s\n- %s",
					a, b, test.method, got, ta, tb)
				return
			}
			if !compareParams {
				return
			}
			if !maps.EqualFunc(gotParams, test.wantParams, types.Identical) {
				t.Errorf("x=%s y=%s method=%s: params: got %v, want %v",
					a, b, test.method, gotParams, test.wantParams)
			}
		}

		check(test.x, test.y, test.want, true)
		// unify is symmetric
		check(test.y, test.x, test.want, true)
		// unify is reflexive
		check(test.x, test.x, true, false)
		check(test.y, test.y, true, false)
	}
}


================================================
FILE: gopls/internal/golang/inlay_hint.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"cmp"
	"context"
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"slices"
	"strings"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

func InlayHint(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, pRng protocol.Range) ([]protocol.InlayHint, error) {
	ctx, done := event.Start(ctx, "golang.InlayHint")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, fmt.Errorf("getting file for InlayHint: %w", err)
	}

	// Collect a list of the inlay hints that are enabled.
	inlayHintOptions := snapshot.Options().InlayHintOptions
	var enabledHints []inlayHintFunc
	for hint, enabled := range inlayHintOptions.Hints {
		if !enabled {
			continue
		}
		if fn, ok := allInlayHints[hint]; ok {
			enabledHints = append(enabledHints, fn)
		}
	}
	if len(enabledHints) == 0 {
		return nil, nil
	}

	info := pkg.TypesInfo()
	qual := typesinternal.FileQualifier(pgf.File, pkg.Types())

	// Set the range to the full file if the range is not valid.
	start, end := pgf.File.FileStart, pgf.File.FileEnd

	// TODO(adonovan): this condition looks completely wrong!
	if pRng.Start.Line < pRng.End.Line || pRng.Start.Character < pRng.End.Character {
		// Adjust start and end for the specified range.
		var err error
		start, end, err = pgf.RangePos(pRng)
		if err != nil {
			return nil, err
		}
	}

	var hints []protocol.InlayHint
	if curSubrange, ok := pgf.Cursor().FindByPos(start, end); ok {
		add := func(hint protocol.InlayHint) { hints = append(hints, hint) }
		for _, fn := range enabledHints {
			fn(info, pgf, qual, curSubrange, add)
		}
	}
	return hints, nil
}

type inlayHintFunc func(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint))

var allInlayHints = map[settings.InlayHint]inlayHintFunc{
	settings.AssignVariableTypes:        assignVariableTypes,
	settings.ConstantValues:             constantValues,
	settings.ParameterNames:             parameterNames,
	settings.RangeVariableTypes:         rangeVariableTypes,
	settings.CompositeLiteralTypes:      compositeLiteralTypes,
	settings.CompositeLiteralFieldNames: compositeLiteralFields,
	settings.FunctionTypeParameters:     funcTypeParams,
	settings.IgnoredError:               ignoredError,
}

func parameterNames(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curCall := range cur.Preorder((*ast.CallExpr)(nil)) {
		callExpr := curCall.Node().(*ast.CallExpr)
		t := info.TypeOf(callExpr.Fun)
		if t == nil {
			continue
		}
		signature, ok := typeparams.CoreType(t).(*types.Signature)
		if !ok {
			continue
		}

		for i, v := range callExpr.Args {
			start, err := pgf.PosPosition(v.Pos())
			if err != nil {
				continue
			}
			params := signature.Params()
			// When a function has variadic params, we skip args after
			// params.Len().
			if i > params.Len()-1 {
				break
			}
			param := params.At(i)
			// param.Name is empty for built-ins like append
			if param.Name() == "" {
				continue
			}
			// Skip the parameter name hint if the arg matches
			// the parameter name.
			if i, ok := v.(*ast.Ident); ok && i.Name == param.Name() {
				continue
			}

			label := param.Name()
			if signature.Variadic() && i == params.Len()-1 {
				label = label + "..."
			}
			add(protocol.InlayHint{
				Position:     start,
				Label:        labelPart(label + ":"),
				Kind:         protocol.Parameter,
				PaddingRight: true,
			})
		}
	}
}

func ignoredError(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
outer:
	for curCall := range cur.Preorder((*ast.ExprStmt)(nil)) {
		stmt := curCall.Node().(*ast.ExprStmt)
		call, ok := stmt.X.(*ast.CallExpr)
		if !ok {
			continue // not a call stmt
		}

		// Check that type of result (or last component) is error.
		tv, ok := info.Types[call]
		if !ok {
			continue // no type info
		}
		t := tv.Type
		if res, ok := t.(*types.Tuple); ok && res.Len() > 1 {
			t = res.At(res.Len() - 1).Type()
		}
		if !types.Identical(t, errorType) {
			continue
		}

		// Suppress some common false positives.
		obj := typeutil.Callee(info, call)
		if typesinternal.IsFunctionNamed(obj, "fmt", "Print", "Printf", "Println", "Fprint", "Fprintf", "Fprintln") ||
			typesinternal.IsMethodNamed(obj, "bytes", "Buffer", "Write", "WriteByte", "WriteRune", "WriteString") ||
			typesinternal.IsMethodNamed(obj, "strings", "Builder", "Write", "WriteByte", "WriteRune", "WriteString") ||
			typesinternal.IsFunctionNamed(obj, "io", "WriteString") {
			continue
		}

		// Suppress if comment on same line contains "// ignore error".
		line := func(pos token.Pos) int { return safetoken.Line(pgf.Tok, pos) }
		comments := pgf.File.Comments
		compare := func(cg *ast.CommentGroup, pos token.Pos) int {
			return cmp.Compare(cg.Pos(), pos)
		}
		i, _ := slices.BinarySearchFunc(comments, stmt.End(), compare)
		if i >= 0 && i < len(comments) {
			cg := comments[i]
			if line(cg.Pos()) == line(stmt.End()) && strings.Contains(cg.Text(), "ignore error") {
				continue outer // suppress
			}
		}

		// Provide a hint.
		pos, err := pgf.PosPosition(stmt.End())
		if err != nil {
			continue
		}
		add(protocol.InlayHint{
			Position: pos,
			Label:    labelPart(" // ignore error"),
		})
	}
}

func funcTypeParams(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curCall := range cur.Preorder((*ast.CallExpr)(nil)) {
		call := curCall.Node().(*ast.CallExpr)
		id, ok := call.Fun.(*ast.Ident)
		if !ok {
			continue
		}
		inst := info.Instances[id]
		if inst.TypeArgs == nil {
			continue
		}
		start, err := pgf.PosPosition(id.End())
		if err != nil {
			continue
		}
		var args []string
		for t := range inst.TypeArgs.Types() {
			args = append(args, t.String())
		}
		if len(args) == 0 {
			continue
		}
		add(protocol.InlayHint{
			Position: start,
			Label:    labelPart("[" + strings.Join(args, ", ") + "]"),
			Kind:     protocol.Type,
		})
	}
}

func assignVariableTypes(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for node := range cur.Preorder((*ast.AssignStmt)(nil), (*ast.ValueSpec)(nil)) {
		switch n := node.Node().(type) {
		case *ast.AssignStmt:
			if n.Tok != token.DEFINE {
				continue
			}
			for _, v := range n.Lhs {
				variableType(info, pgf, qual, v, add)
			}
		case *ast.GenDecl:
			if n.Tok != token.VAR {
				continue
			}
			for _, v := range n.Specs {
				spec := v.(*ast.ValueSpec)
				// The type of the variable is written, skip showing type of this var.
				// ```go
				// var foo string
				// ```
				if spec.Type != nil {
					continue
				}

				for _, v := range spec.Names {
					variableType(info, pgf, qual, v, add)
				}
			}
		}
	}
}

func rangeVariableTypes(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curRange := range cur.Preorder((*ast.RangeStmt)(nil)) {
		rStmt := curRange.Node().(*ast.RangeStmt)
		variableType(info, pgf, qual, rStmt.Key, add)
		variableType(info, pgf, qual, rStmt.Value, add)
	}
}

func variableType(info *types.Info, pgf *parsego.File, qual types.Qualifier, e ast.Expr, add func(protocol.InlayHint)) {
	typ := info.TypeOf(e)
	if typ == nil {
		return
	}
	end, err := pgf.PosPosition(e.End())
	if err != nil {
		return
	}
	add(protocol.InlayHint{
		Position:    end,
		Label:       labelPart(types.TypeString(typ, qual)),
		Kind:        protocol.Type,
		PaddingLeft: true,
	})
}

func constantValues(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curDecl := range cur.Preorder((*ast.GenDecl)(nil)) {
		genDecl := curDecl.Node().(*ast.GenDecl)
		if genDecl.Tok != token.CONST {
			continue
		}

		for _, v := range genDecl.Specs {
			spec, ok := v.(*ast.ValueSpec)
			if !ok {
				continue
			}
			end, err := pgf.PosPosition(v.End())
			if err != nil {
				continue
			}
			// Show hints when values are missing or at least one value is not
			// a basic literal.
			showHints := len(spec.Values) == 0
			checkValues := len(spec.Names) == len(spec.Values)
			var values []string
			for i, w := range spec.Names {
				obj, ok := info.ObjectOf(w).(*types.Const)
				if !ok || obj.Val().Kind() == constant.Unknown {
					continue
				}
				if checkValues {
					switch spec.Values[i].(type) {
					case *ast.BadExpr:
						continue
					case *ast.BasicLit:
					default:
						if obj.Val().Kind() != constant.Bool {
							showHints = true
						}
					}
				}
				values = append(values, fmt.Sprintf("%v", obj.Val()))
			}
			if !showHints || len(values) == 0 {
				continue
			}
			add(protocol.InlayHint{
				Position:    end,
				Label:       labelPart("= " + strings.Join(values, ", ")),
				PaddingLeft: true,
			})
		}
	}
}

func compositeLiteralFields(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curCompLit := range cur.Preorder((*ast.CompositeLit)(nil)) {
		compLit, ok := curCompLit.Node().(*ast.CompositeLit)
		if !ok {
			continue
		}
		typ := info.TypeOf(compLit)
		if typ == nil {
			continue
		}
		typ = typesinternal.Unpointer(typ)
		strct, ok := typeparams.CoreType(typ).(*types.Struct)
		if !ok {
			continue
		}

		var hints []protocol.InlayHint
		var allEdits []protocol.TextEdit
		for i, v := range compLit.Elts {
			if _, ok := v.(*ast.KeyValueExpr); !ok {
				start, err := pgf.PosPosition(v.Pos())
				if err != nil {
					continue
				}
				if i > strct.NumFields()-1 {
					break
				}
				hints = append(hints, protocol.InlayHint{
					Position:     start,
					Label:        labelPart(strct.Field(i).Name() + ":"),
					Kind:         protocol.Parameter,
					PaddingRight: true,
				})
				allEdits = append(allEdits, protocol.TextEdit{
					Range:   protocol.Range{Start: start, End: start},
					NewText: strct.Field(i).Name() + ": ",
				})
			}
		}
		// It is not allowed to have a mix of keyed and unkeyed fields, so
		// have the text edits add keys to all fields.
		for i := range hints {
			hints[i].TextEdits = allEdits
			add(hints[i])
		}
	}
}

func compositeLiteralTypes(info *types.Info, pgf *parsego.File, qual types.Qualifier, cur inspector.Cursor, add func(protocol.InlayHint)) {
	for curCompLit := range cur.Preorder((*ast.CompositeLit)(nil)) {
		compLit := curCompLit.Node().(*ast.CompositeLit)
		typ := info.TypeOf(compLit)
		if typ == nil {
			continue
		}
		if compLit.Type != nil {
			continue
		}
		prefix := ""
		if t, ok := typeparams.CoreType(typ).(*types.Pointer); ok {
			typ = t.Elem()
			prefix = "&"
		}
		// The type for this composite literal is implicit, add an inlay hint.
		start, err := pgf.PosPosition(compLit.Lbrace)
		if err != nil {
			continue
		}
		add(protocol.InlayHint{
			Position: start,
			Label:    labelPart(fmt.Sprintf("%s%s", prefix, types.TypeString(typ, qual))),
			Kind:     protocol.Type,
		})
	}
}

func labelPart(s string) []protocol.InlayHintLabelPart {
	const maxLabelLength = 28
	if len(s) > maxLabelLength+len("...") {
		s = s[:maxLabelLength] + "..."
	}
	return []protocol.InlayHintLabelPart{{Value: s}}
}


================================================
FILE: gopls/internal/golang/inline.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines the refactor.inline code action.

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/analysis"
	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/refactor/inline"
)

// enclosingStaticCall returns the innermost function call enclosing
// the selected range, along with the callee.
func enclosingStaticCall(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*ast.CallExpr, *types.Func, error) {
	// TODO(adonovan): simplify using pgf.Cursor
	path, _ := goastutil.PathEnclosingInterval(pgf.File, start, end)

	var call *ast.CallExpr
loop:
	for _, n := range path {
		switch n := n.(type) {
		case *ast.FuncLit:
			break loop
		case *ast.CallExpr:
			call = n
			break loop
		}
	}
	if call == nil {
		return nil, nil, fmt.Errorf("no enclosing call")
	}
	if safetoken.Line(pgf.Tok, call.Lparen) != safetoken.Line(pgf.Tok, start) {
		return nil, nil, fmt.Errorf("enclosing call is not on this line")
	}
	fn := typeutil.StaticCallee(pkg.TypesInfo(), call)
	if fn == nil {
		return nil, nil, fmt.Errorf("not a static call to a Go function")
	}
	return call, fn, nil
}

func inlineCall(ctx context.Context, snapshot *cache.Snapshot, callerPkg *cache.Package, callerPGF *parsego.File, start, end token.Pos) (_ *token.FileSet, _ *analysis.SuggestedFix, err error) {
	countInlineCall.Inc()
	// Find enclosing static call.
	call, fn, err := enclosingStaticCall(callerPkg, callerPGF, start, end)
	if err != nil {
		return nil, nil, err
	}

	calleePkg, calleePGF, calleePos, err := NarrowestDeclaringPackage(ctx, snapshot, callerPkg, fn)
	if err != nil {
		return nil, nil, err
	}

	var calleeDecl *ast.FuncDecl
	for _, decl := range calleePGF.File.Decls {
		funcDecl, ok := decl.(*ast.FuncDecl)
		if !ok {
			continue
		}
		if funcDecl.Name.Pos() == calleePos {
			calleeDecl = funcDecl
			break
		}
	}
	if calleeDecl == nil {
		return nil, nil, fmt.Errorf("can't find callee")
	}

	// The inliner assumes that input is well-typed,
	// but that is frequently not the case within gopls.
	// Until we are able to harden the inliner,
	// report panics as errors to avoid crashing the server.
	bad := func(p *cache.Package) bool { return len(p.ParseErrors())+len(p.TypeErrors()) > 0 }
	if bad(calleePkg) || bad(callerPkg) {
		defer func() {
			if x := recover(); x != nil {
				err = fmt.Errorf("inlining failed (%q), likely because inputs were ill-typed", x)
			}
		}()
	}

	// Users can consult the gopls event log to see
	// why a particular inlining strategy was chosen.
	logf := logger(ctx, "inliner", snapshot.Options().VerboseOutput)

	callee, err := inline.AnalyzeCallee(logf, calleePkg.FileSet(), calleePkg.Types(), calleePkg.TypesInfo(), calleeDecl, calleePGF.Src)
	if err != nil {
		return nil, nil, err
	}

	// Inline the call.
	caller := &inline.Caller{
		Fset:      callerPkg.FileSet(),
		Types:     callerPkg.Types(),
		Info:      callerPkg.TypesInfo(),
		File:      callerPGF.File,
		Call:      call,
		CountUses: nil, // (use inefficient default implementation)
	}

	res, err := inline.Inline(caller, callee, &inline.Options{Logf: logf})
	if err != nil {
		return nil, nil, err
	}

	return callerPkg.FileSet(), &analysis.SuggestedFix{
		Message:   fmt.Sprintf("inline call of %v", callee),
		TextEdits: res.Edits,
	}, nil
}

// TODO(adonovan): change the inliner to instead accept an io.Writer.
func logger(ctx context.Context, name string, verbose bool) func(format string, args ...any) {
	if verbose {
		return func(format string, args ...any) {
			event.Log(ctx, name+": "+fmt.Sprintf(format, args...))
		}
	} else {
		return func(string, ...any) {}
	}
}

// canInlineVariable reports whether the selection is within an
// identifier that is a use of a variable that has an initializer
// expression. If so, it returns cursors for the identifier and the
// initializer expression.
func canInlineVariable(info *types.Info, curFile inspector.Cursor, start, end token.Pos) (_, _ inspector.Cursor, ok bool) {
	if curUse, ok := curFile.FindByPos(start, end); ok {
		if id, ok := curUse.Node().(*ast.Ident); ok && !isLvalueUse(curUse, info) {
			if v, ok := info.Uses[id].(*types.Var); ok && v.Kind() == types.LocalVar {
				if curIdent, ok := curFile.FindByPos(v.Pos(), v.Pos()); ok {
					curParent := curIdent.Parent()
					kind, index := curIdent.ParentEdge()
					switch kind {
					case edge.ValueSpec_Names:
						// var v = expr
						spec := curParent.Node().(*ast.ValueSpec)
						if len(spec.Names) == len(spec.Values) {
							return curUse, curParent.ChildAt(edge.ValueSpec_Values, index), true
						}
					case edge.AssignStmt_Lhs:
						// v := expr
						stmt := curParent.Node().(*ast.AssignStmt)
						if len(stmt.Lhs) == len(stmt.Rhs) {
							return curUse, curParent.ChildAt(edge.AssignStmt_Rhs, index), true
						}
					}
				}
			}
		}
	}
	return
}

// isLvalueUse reports whether the "use" identifier represented by cur
// appears in an l-value context such as:
//
//   - v=...
//   - v++
//   - &v
//   - v.f(), when this implicitly takes the address of v.
func isLvalueUse(cur inspector.Cursor, info *types.Info) bool {
	cur = unparenEnclosing(cur)

	switch cur.ParentEdgeKind() {
	case edge.AssignStmt_Lhs, edge.IncDecStmt_X:
		return true // v=..., v++

	case edge.UnaryExpr_X:
		return cur.Parent().Node().(*ast.UnaryExpr).Op == token.AND // &v

	case edge.SelectorExpr_X:
		sel := cur.Parent().Node().(*ast.SelectorExpr)
		isPointer := func(t types.Type) bool {
			return is[*types.Pointer](t)
		}
		if seln, ok := info.Selections[sel]; ok && seln.Kind() == types.MethodVal {
			// Have: recv.f() method call
			methodRecv := seln.Obj().(*types.Func).Signature().Recv().Type()
			return !seln.Indirect() && isPointer(methodRecv) && !isPointer(info.TypeOf(sel.X))
		}
	}

	return false
}

// unparenEnclosing removes enclosing parens from cur in
// preparation for a call to [Cursor.ParentEdge].
func unparenEnclosing(cur inspector.Cursor) inspector.Cursor {
	for cur.ParentEdgeKind() == edge.ParenExpr_X {
		cur = cur.Parent()
	}
	return cur
}

// inlineVariableOne computes a fix to replace the selected variable by
// its initialization expression.
func inlineVariableOne(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	countInlineVariable.Inc()
	info := pkg.TypesInfo()
	curUse, curRHS, ok := canInlineVariable(info, pgf.Cursor(), start, end)
	if !ok {
		return nil, nil, fmt.Errorf("cannot inline variable here")
	}

	// Check that free symbols of rhs are unshadowed at curUse.
	var (
		use   = curUse.Node().(*ast.Ident)
		rhs   = curRHS.Node().(ast.Expr)
		pos   = use.Pos()
		scope = info.Scopes[pgf.File].Innermost(pos)
	)
	for curIdent := range curRHS.Preorder((*ast.Ident)(nil)) {
		if curIdent.ParentEdgeKind() == edge.SelectorExpr_Sel {
			continue // ignore f in x.f
		}
		id := curIdent.Node().(*ast.Ident)
		obj1 := info.Uses[id]
		if obj1 == nil {
			continue // undefined; or a def, not a use
		}
		if v, ok := obj1.(*types.Var); ok && v.IsField() {
			continue // a field reference T{F: 0} is non-lexical
		}
		if astutil.NodeContainsPos(rhs, obj1.Pos()) {
			continue // not free (id is defined within RHS)
		}
		_, obj2 := scope.LookupParent(id.Name, pos)
		// Inv: obj2 is non-nil.
		if obj1 != obj2 {
			return nil, nil, fmt.Errorf("cannot inline variable: its initializer expression refers to %q, which is shadowed by the declaration at line %d", id.Name, safetoken.Position(pgf.Tok, obj2.Pos()).Line)
		}
	}

	// TODO(adonovan): also reject variables that are updated by assignments?

	// Add parens to 'new' as needed by the 'use' context.
	rhs = astutil.MaybeParenthesize(curUse.Parent().Node(), use, rhs)

	return pkg.FileSet(), &analysis.SuggestedFix{
		Message: fmt.Sprintf("Replace variable %q by its initializer expression", use.Name),
		TextEdits: []analysis.TextEdit{
			{
				Pos:     use.Pos(),
				End:     use.End(),
				NewText: []byte(FormatNode(pkg.FileSet(), rhs)),
			},
		},
	}, nil
}


================================================
FILE: gopls/internal/golang/inline_all.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/parser"
	"go/types"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/analysis/driverutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/refactor/inline"
)

// inlineAllCalls inlines all calls to the original function declaration
// described by callee, returning the resulting modified file content.
//
// inlining everything is currently an expensive operation: it involves re-type
// checking every package that contains a potential call, as reported by
// References. In cases where there are multiple calls per file, inlineAllCalls
// must type check repeatedly for each additional call.
//
// The provided post processing function is applied to the resulting source
// after each transformation. This is necessary because we are using this
// function to inline synthetic wrappers for the purpose of signature
// rewriting. The delegated function has a fake name that doesn't exist in the
// snapshot, and so we can't re-type check until we replace this fake name.
//
// TODO(rfindley): this only works because removing a parameter is a very
// narrow operation. A better solution would be to allow for ad-hoc snapshots
// that expose the full machinery of real snapshots: minimal invalidation,
// batched type checking, etc. Then we could actually rewrite the declaring
// package in this snapshot (and so 'post' would not be necessary), and could
// robustly re-type check for the purpose of iterative inlining, even if the
// inlined code pulls in new imports that weren't present in export data.
//
// The code below notes where are assumptions are made that only hold true in
// the case of parameter removal (annotated with 'Assumption:')
func inlineAllCalls(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, origDecl *ast.FuncDecl, callee *inline.Callee, post func([]byte) []byte, opts *inline.Options) (_ map[protocol.DocumentURI][]byte, inlineErr error) {
	// Collect references.
	var refs []protocol.Location
	{
		funcRng, err := pgf.Mapper.PosRange(pgf.Tok, origDecl.Name.NamePos, origDecl.Name.NamePos)
		if err != nil {
			return nil, err
		}
		fh, err := snapshot.ReadFile(ctx, pgf.URI)
		if err != nil {
			return nil, err
		}
		refs, err = References(ctx, snapshot, fh, funcRng, false)
		if err != nil {
			return nil, fmt.Errorf("finding references to rewrite: %v", err)
		}
	}

	// Type-check the narrowest package containing each reference.
	// TODO(rfindley): we should expose forEachPackage in order to operate in
	// parallel and to reduce peak memory for this operation.
	var (
		pkgForRef = make(map[protocol.Location]PackageID)
		pkgs      = make(map[PackageID]*cache.Package)
		// The inliner assumes that input is well-typed, but that is frequently not
		// the case within gopls.
		// Until we're able to harden the inliner, report panics as errors to avoid
		// crashing the server.
		badPkg = false
	)
	{
		needPkgs := make(map[PackageID]struct{})
		for _, ref := range refs {
			md, err := snapshot.NarrowestMetadataForFile(ctx, ref.URI)
			if err != nil {
				return nil, fmt.Errorf("finding ref metadata: %v", err)
			}
			pkgForRef[ref] = md.ID
			needPkgs[md.ID] = struct{}{}
		}
		var pkgIDs []PackageID
		for id := range needPkgs { // TODO: use maps.Keys once it is available to us
			pkgIDs = append(pkgIDs, id)
		}

		refPkgs, err := snapshot.TypeCheck(ctx, pkgIDs...)
		if err != nil {
			return nil, fmt.Errorf("type checking reference packages: %v", err)
		}

		for _, p := range refPkgs {
			pkgs[p.Metadata().ID] = p
			if len(p.ParseErrors())+len(p.TypeErrors()) > 0 {
				badPkg = true
			}
		}
	}

	if badPkg {
		defer func() {
			if x := recover(); x != nil {
				inlineErr = fmt.Errorf("inlining failed (%q), likely because inputs were ill-typed", x)
			}
		}()
	}

	// Organize calls by top file declaration. Calls within a single file may
	// affect each other, as the inlining edit may affect the surrounding scope
	// or imports Therefore, when inlining subsequent calls in the same
	// declaration, we must re-type check.

	type fileCalls struct {
		pkg   *cache.Package
		pgf   *parsego.File
		calls []*ast.CallExpr
	}

	refsByFile := make(map[protocol.DocumentURI]*fileCalls)
	for _, ref := range refs {
		refpkg := pkgs[pkgForRef[ref]]
		pgf, err := refpkg.File(ref.URI)
		if err != nil {
			return nil, bug.Errorf("finding %s in %s: %v", ref.URI, refpkg.Metadata().ID, err)
		}

		start, end, err := pgf.RangePos(ref.Range)
		if err != nil {
			return nil, err // e.g. invalid range
		}

		// Look for the surrounding call expression.
		var (
			name *ast.Ident
			call *ast.CallExpr
		)
		path, _ := astutil.PathEnclosingInterval(pgf.File, start, end)
		name, _ = path[0].(*ast.Ident)

		// TODO(rfindley): handle method expressions correctly.
		if _, ok := path[1].(*ast.SelectorExpr); ok {
			call, _ = path[2].(*ast.CallExpr)
		} else {
			call, _ = path[1].(*ast.CallExpr)
		}
		if name == nil || call == nil {
			// TODO(rfindley): handle this case with eta-abstraction:
			// a reference to the target function f in a non-call position
			//    use(f)
			// is replaced by
			//    use(func(...) { f(...) })
			return nil, fmt.Errorf("cannot inline: found non-call function reference %v", ref)
		}

		// Heuristic: ignore references that overlap with type checker errors, as they may
		// lead to invalid results (see golang/go#70268).
		hasTypeErrors := false
		for _, typeErr := range refpkg.TypeErrors() {
			if call.Lparen <= typeErr.Pos && typeErr.Pos <= call.Rparen {
				hasTypeErrors = true
			}
		}

		if hasTypeErrors {
			continue
		}

		if typeutil.StaticCallee(refpkg.TypesInfo(), call) == nil {
			continue // dynamic call
		}

		// Sanity check.
		if obj := refpkg.TypesInfo().ObjectOf(name); obj == nil ||
			obj.Name() != origDecl.Name.Name ||
			obj.Pkg() == nil ||
			obj.Pkg().Path() != string(pkg.Metadata().PkgPath) {

			return nil, bug.Errorf("cannot inline: corrupted reference %v", ref)
		}

		callInfo, ok := refsByFile[ref.URI]
		if !ok {
			callInfo = &fileCalls{
				pkg: refpkg,
				pgf: pgf,
			}
			refsByFile[ref.URI] = callInfo
		}
		callInfo.calls = append(callInfo.calls, call)
	}

	// Inline each call within the same decl in sequence, re-typechecking after
	// each one. If there is only a single call within the decl, we can avoid
	// additional type checking.
	//
	// Assumption: inlining does not affect the package scope, so we can operate
	// on separate files independently.
	result := make(map[protocol.DocumentURI][]byte)
	for uri, callInfo := range refsByFile {
		var (
			calls   = callInfo.calls
			fset    = callInfo.pkg.FileSet()
			tpkg    = callInfo.pkg.Types()
			tinfo   = callInfo.pkg.TypesInfo()
			file    = callInfo.pgf.File
			content = callInfo.pgf.Src
		)

		// Check for overlapping calls (such as Foo(Foo())). We can't handle these
		// because inlining may change the source order of the inner call with
		// respect to the inlined outer call, and so the heuristic we use to find
		// the next call (counting from top-to-bottom) does not work.
		for i := range calls {
			if i > 0 && calls[i-1].End() > calls[i].Pos() {
				return nil, fmt.Errorf("%s: can't inline overlapping call %s", uri, types.ExprString(calls[i-1]))
			}
		}

		currentCall := 0
		for currentCall < len(calls) {
			caller := &inline.Caller{
				Fset:      fset,
				Types:     tpkg,
				Info:      tinfo,
				File:      file,
				Call:      calls[currentCall],
				CountUses: nil, // TODO(adonovan): opt: amortize across callInfo.pkg
			}
			res, err := inline.Inline(caller, callee, opts)
			if err != nil {
				return nil, fmt.Errorf("inlining failed: %v", err)
			}

			// applyEdits transforms content by applying the specified edits
			// (whose positions are defined by fset), reformatting the file, and
			// removing unused imports (using pkg for names of imported packages).
			// (Adapted from inline_test.applyEdits.)
			applyEdits := func(content []byte, edits []refactor.Edit) ([]byte, error) {
				dedits := make([]diff.Edit, len(edits))
				for i, edit := range edits {
					dedits[i] = diff.Edit{
						Start: int(edit.Pos - file.FileStart),
						End:   int(edit.End - file.FileStart),
						New:   string(edit.NewText),
					}
				}
				got, err := diff.ApplyBytes(content, dedits)
				if err != nil {
					return nil, err // inliner produced invalid edits
				}
				got, err = driverutil.FormatSourceRemoveImports(tpkg, got)
				if err != nil {
					return nil, err // failed to parse+print
				}
				return []byte(got), nil
			}

			content, err = applyEdits(content, res.Edits)
			if err != nil {
				return nil, fmt.Errorf("applying inliner edits failed: %v", err)
			}

			if post != nil {
				content = post(content)
			}
			if len(calls) <= 1 {
				// No need to re-type check, as we've inlined all calls.
				break
			}

			// TODO(rfindley): develop a theory of "trivial" inlining, which are
			// inlinings that don't require re-type checking.
			//
			// In principle, if the inlining only involves replacing one call with
			// another, the scope of the caller is unchanged and there is no need to
			// type check again before inlining subsequent calls (edits should not
			// overlap, and should not affect each other semantically). However, it
			// feels sufficiently complicated that, to be safe, this optimization is
			// deferred until later.

			file, err = parser.ParseFile(fset, uri.Path(), content, parser.ParseComments|parser.SkipObjectResolution)
			if err != nil {
				return nil, bug.Errorf("inlined file failed to parse: %v", err)
			}

			// After inlining one call with a removed parameter, the package will
			// fail to type check due to "not enough arguments". Therefore, we must
			// allow type errors here.
			//
			// Assumption: the resulting type errors do not affect the correctness of
			// subsequent inlining, because invalid arguments to a call do not affect
			// anything in the surrounding scope.
			//
			// TODO(rfindley): improve this.
			logf := func(string, ...any) {}
			if opts != nil {
				logf = opts.Logf
			}
			tpkg, tinfo, err = reTypeCheck(logf, callInfo.pkg, map[protocol.DocumentURI]*ast.File{uri: file}, true)
			if err != nil {
				return nil, bug.Errorf("type checking after inlining failed: %v", err)
			}

			// Collect calls to the target function in the modified declaration.
			var calls2 []*ast.CallExpr
			ast.Inspect(file, func(n ast.Node) bool {
				if call, ok := n.(*ast.CallExpr); ok {
					fn := typeutil.StaticCallee(tinfo, call)
					if fn != nil && fn.Pkg().Path() == string(pkg.Metadata().PkgPath) && fn.Name() == origDecl.Name.Name {
						calls2 = append(calls2, call)
					}
				}
				return true
			})

			// If the number of calls has increased, this process will never cease.
			// If the number of calls has decreased, assume that inlining removed a
			// call.
			// If the number of calls didn't change, assume that inlining replaced
			// a call, and move on to the next.
			//
			// Assumption: we're inlining a call that has at most one recursive
			// reference (which holds for signature rewrites).
			//
			// TODO(rfindley): this isn't good enough. We should be able to support
			// inlining all existing calls even if they increase calls. How do we
			// correlate the before and after syntax?
			switch {
			case len(calls2) > len(calls):
				return nil, fmt.Errorf("inlining increased calls %d->%d, possible recursive call? content:\n%s", len(calls), len(calls2), content)
			case len(calls2) < len(calls):
				calls = calls2
			case len(calls2) == len(calls):
				calls = calls2
				currentCall++
			}
		}

		result[callInfo.pgf.URI] = content
	}
	return result, nil
}


================================================
FILE: gopls/internal/golang/invertifcondition.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"fmt"
	"go/ast"
	"go/token"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// invertIfCondition is a singleFileFixFunc that inverts an if/else statement
func invertIfCondition(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	var (
		fset = pkg.FileSet()
		src  = pgf.Src
	)

	ifStatement, _, err := canInvertIfCondition(pgf.Cursor(), start, end)
	if err != nil {
		return nil, nil, err
	}

	var replaceElse analysis.TextEdit

	endsWithReturn, err := endsWithReturn(ifStatement.Else)
	if err != nil {
		return nil, nil, err
	}

	if endsWithReturn {
		// Replace the whole else part with an empty line and an unindented
		// version of the original if body
		sourcePos := safetoken.StartPosition(fset, ifStatement.Pos())

		indent := max(sourcePos.Column-1, 0)

		standaloneBodyText := ifBodyToStandaloneCode(fset, ifStatement.Body, src)
		replaceElse = analysis.TextEdit{
			Pos:     ifStatement.Body.Rbrace + 1, // 1 == len("}")
			End:     ifStatement.End(),
			NewText: []byte("\n\n" + strings.Repeat("\t", indent) + standaloneBodyText),
		}
	} else {
		// Replace the else body text with the if body text
		bodyStart := safetoken.StartPosition(fset, ifStatement.Body.Lbrace)
		bodyEnd := safetoken.EndPosition(fset, ifStatement.Body.Rbrace+1) // 1 == len("}")
		bodyText := src[bodyStart.Offset:bodyEnd.Offset]
		replaceElse = analysis.TextEdit{
			Pos:     ifStatement.Else.Pos(),
			End:     ifStatement.Else.End(),
			NewText: bodyText,
		}
	}

	// Replace the if text with the else text
	elsePosInSource := safetoken.StartPosition(fset, ifStatement.Else.Pos())
	elseEndInSource := safetoken.EndPosition(fset, ifStatement.Else.End())
	elseText := src[elsePosInSource.Offset:elseEndInSource.Offset]
	replaceBodyWithElse := analysis.TextEdit{
		Pos:     ifStatement.Body.Pos(),
		End:     ifStatement.Body.End(),
		NewText: elseText,
	}

	// Replace the if condition with its inverse
	inverseCondition, err := invertCondition(fset, ifStatement.Cond, src)
	if err != nil {
		return nil, nil, err
	}
	replaceConditionWithInverse := analysis.TextEdit{
		Pos:     ifStatement.Cond.Pos(),
		End:     ifStatement.Cond.End(),
		NewText: inverseCondition,
	}

	// Return a SuggestedFix with just that TextEdit in there
	return fset, &analysis.SuggestedFix{
		TextEdits: []analysis.TextEdit{
			replaceConditionWithInverse,
			replaceBodyWithElse,
			replaceElse,
		},
	}, nil
}

func endsWithReturn(elseBranch ast.Stmt) (bool, error) {
	elseBlock, isBlockStatement := elseBranch.(*ast.BlockStmt)
	if !isBlockStatement {
		return false, fmt.Errorf("unable to figure out whether this ends with return: %T", elseBranch)
	}

	if len(elseBlock.List) == 0 {
		// Empty blocks don't end in returns
		return false, nil
	}

	lastStatement := elseBlock.List[len(elseBlock.List)-1]

	_, lastStatementIsReturn := lastStatement.(*ast.ReturnStmt)
	return lastStatementIsReturn, nil
}

// Turn { fmt.Println("Hello") } into just fmt.Println("Hello"), with one less
// level of indentation.
//
// The first line of the result will not be indented, but all of the following
// lines will.
func ifBodyToStandaloneCode(fset *token.FileSet, ifBody *ast.BlockStmt, src []byte) string {
	// Get the whole body (without the surrounding braces) as a string
	bodyStart := safetoken.StartPosition(fset, ifBody.Lbrace+1) // 1 == len("}")
	bodyEnd := safetoken.EndPosition(fset, ifBody.Rbrace)
	bodyWithoutBraces := string(src[bodyStart.Offset:bodyEnd.Offset])
	bodyWithoutBraces = strings.TrimSpace(bodyWithoutBraces)

	// Unindent
	bodyWithoutBraces = strings.ReplaceAll(bodyWithoutBraces, "\n\t", "\n")

	return bodyWithoutBraces
}

func invertCondition(fset *token.FileSet, cond ast.Expr, src []byte) ([]byte, error) {
	condStart := safetoken.StartPosition(fset, cond.Pos())
	condEnd := safetoken.EndPosition(fset, cond.End())
	oldText := string(src[condStart.Offset:condEnd.Offset])

	switch expr := cond.(type) {
	case *ast.Ident, *ast.ParenExpr, *ast.CallExpr, *ast.StarExpr, *ast.IndexExpr, *ast.IndexListExpr, *ast.SelectorExpr:
		newText := "!" + oldText
		if oldText == "true" {
			newText = "false"
		} else if oldText == "false" {
			newText = "true"
		}

		return []byte(newText), nil

	case *ast.UnaryExpr:
		if expr.Op != token.NOT {
			// This should never happen
			return dumbInvert(fset, cond, src), nil
		}

		inverse := expr.X
		if p, isParen := inverse.(*ast.ParenExpr); isParen {
			// We got !(x), remove the parentheses with the ! so we get just "x"
			inverse = p.X

			start := safetoken.StartPosition(fset, inverse.Pos())
			end := safetoken.EndPosition(fset, inverse.End())
			if start.Line != end.Line {
				// The expression is multi-line, so we can't remove the parentheses
				inverse = expr.X
			}
		}

		start := safetoken.StartPosition(fset, inverse.Pos())
		end := safetoken.EndPosition(fset, inverse.End())
		textWithoutNot := src[start.Offset:end.Offset]

		return textWithoutNot, nil

	case *ast.BinaryExpr:
		// These inversions are unsound for floating point NaN, but that's ok.
		negations := map[token.Token]string{
			token.EQL: "!=",
			token.LSS: ">=",
			token.GTR: "<=",
			token.NEQ: "==",
			token.LEQ: ">",
			token.GEQ: "<",
		}

		negation, negationFound := negations[expr.Op]
		if !negationFound {
			return invertAndOr(fset, expr, src)
		}

		xPosInSource := safetoken.StartPosition(fset, expr.X.Pos())
		opPosInSource := safetoken.StartPosition(fset, expr.OpPos)
		yPosInSource := safetoken.StartPosition(fset, expr.Y.Pos())

		textBeforeOp := string(src[xPosInSource.Offset:opPosInSource.Offset])

		oldOpWithTrailingWhitespace := string(src[opPosInSource.Offset:yPosInSource.Offset])
		newOpWithTrailingWhitespace := negation + oldOpWithTrailingWhitespace[len(expr.Op.String()):]

		textAfterOp := string(src[yPosInSource.Offset:condEnd.Offset])

		return []byte(textBeforeOp + newOpWithTrailingWhitespace + textAfterOp), nil
	}

	return dumbInvert(fset, cond, src), nil
}

// dumbInvert is a fallback, inverting cond into !(cond).
func dumbInvert(fset *token.FileSet, expr ast.Expr, src []byte) []byte {
	start := safetoken.StartPosition(fset, expr.Pos())
	end := safetoken.EndPosition(fset, expr.End())
	text := string(src[start.Offset:end.Offset])
	return []byte("!(" + text + ")")
}

func invertAndOr(fset *token.FileSet, expr *ast.BinaryExpr, src []byte) ([]byte, error) {
	if expr.Op != token.LAND && expr.Op != token.LOR {
		// Neither AND nor OR, don't know how to invert this
		return dumbInvert(fset, expr, src), nil
	}

	oppositeOp := "&&"
	if expr.Op == token.LAND {
		oppositeOp = "||"
	}

	xEndInSource := safetoken.EndPosition(fset, expr.X.End())
	opPosInSource := safetoken.StartPosition(fset, expr.OpPos)
	whitespaceAfterBefore := src[xEndInSource.Offset:opPosInSource.Offset]

	invertedBefore, err := invertCondition(fset, expr.X, src)
	if err != nil {
		return nil, err
	}

	invertedAfter, err := invertCondition(fset, expr.Y, src)
	if err != nil {
		return nil, err
	}

	yPosInSource := safetoken.StartPosition(fset, expr.Y.Pos())

	oldOpWithTrailingWhitespace := string(src[opPosInSource.Offset:yPosInSource.Offset])
	newOpWithTrailingWhitespace := oppositeOp + oldOpWithTrailingWhitespace[len(expr.Op.String()):]

	return []byte(string(invertedBefore) + string(whitespaceAfterBefore) + newOpWithTrailingWhitespace + string(invertedAfter)), nil
}

// canInvertIfCondition reports whether we can do invert-if-condition on the
// code in the given range.
func canInvertIfCondition(curFile inspector.Cursor, start, end token.Pos) (*ast.IfStmt, bool, error) {
	curIf, _ := curFile.FindByPos(start, end)
	stmt, _ := cursorutil.FirstEnclosing[*ast.IfStmt](curIf)
	if stmt == nil {
		return nil, false, fmt.Errorf("not an if statement")
	}
	if stmt.Else == nil {
		// Can't invert conditions without else clauses
		return nil, false, fmt.Errorf("else clause required")
	}

	if _, hasElseIf := stmt.Else.(*ast.IfStmt); hasElseIf {
		// Can't invert conditions with else-if clauses, unclear what that
		// would look like
		return nil, false, fmt.Errorf("else-if not supported")
	}

	return stmt, true, nil
}


================================================
FILE: gopls/internal/golang/known_packages.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"go/parser"
	"go/token"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/imports"
)

// KnownPackagePaths returns a new list of package paths of all known
// packages in the package graph that could potentially be imported by
// the given file. The list is ordered lexicographically, except that
// all dot-free paths (standard packages) appear before dotful ones.
//
// It is part of the gopls.list_known_packages command.
func KnownPackagePaths(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]PackagePath, error) {
	// This algorithm is expressed in terms of Metadata, not Packages,
	// so it doesn't cause or wait for type checking.

	current, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
	if err != nil {
		return nil, err // e.g. context cancelled
	}

	// Parse the file's imports so we can compute which
	// PackagePaths are imported by this specific file.
	src, err := fh.Content()
	if err != nil {
		return nil, err
	}
	file, err := parser.ParseFile(token.NewFileSet(), fh.URI().Path(), src, parser.ImportsOnly)
	if err != nil {
		return nil, err
	}
	imported := make(map[PackagePath]bool)
	for _, imp := range file.Imports {
		if id := current.DepsByImpPath[metadata.UnquoteImportPath(imp)]; id != "" {
			if mp := snapshot.Metadata(id); mp != nil {
				imported[mp.PkgPath] = true
			}
		}
	}

	// Now find candidates among all known packages.
	knownPkgs, err := snapshot.AllMetadata(ctx)
	if err != nil {
		return nil, err
	}
	seen := make(map[PackagePath]bool)
	for _, knownPkg := range knownPkgs {
		// package main cannot be imported
		if knownPkg.Name == "main" {
			continue
		}
		// test packages cannot be imported
		if knownPkg.ForTest != "" {
			continue
		}
		// No need to import what the file already imports.
		// This check is based on PackagePath, not PackageID,
		// so that all test variants are filtered out too.
		if imported[knownPkg.PkgPath] {
			continue
		}
		// make sure internal packages are importable by the file
		if !metadata.IsValidImport(current.PkgPath, knownPkg.PkgPath, snapshot.View().Type() != cache.GoPackagesDriverView) {
			continue
		}
		// naive check on cyclical imports
		if isDirectlyCyclical(current, knownPkg) {
			continue
		}
		// AllMetadata may have multiple variants of a pkg.
		seen[knownPkg.PkgPath] = true
	}

	// Augment the set by invoking the goimports algorithm.
	if err := snapshot.RunProcessEnvFunc(ctx, func(ctx context.Context, o *imports.Options) error {
		ctx, cancel := context.WithTimeout(ctx, time.Millisecond*80)
		defer cancel()
		var seenMu sync.Mutex
		wrapped := func(ifix imports.ImportFix) {
			seenMu.Lock()
			defer seenMu.Unlock()
			// TODO(adonovan): what if the actual package path has a vendor/ prefix?
			seen[PackagePath(ifix.StmtInfo.ImportPath)] = true
		}
		return imports.GetAllCandidates(ctx, wrapped, "", fh.URI().Path(), string(current.Name), o.Env)
	}); err != nil {
		// If goimports failed, proceed with just the candidates from the metadata.
		event.Error(ctx, "imports.GetAllCandidates", err)
	}

	// Sort lexicographically, but with std before non-std packages.
	paths := make([]PackagePath, 0, len(seen))
	for path := range seen {
		paths = append(paths, path)
	}
	sort.Slice(paths, func(i, j int) bool {
		importI, importJ := paths[i], paths[j]
		iHasDot := strings.Contains(string(importI), ".")
		jHasDot := strings.Contains(string(importJ), ".")
		if iHasDot != jHasDot {
			return jHasDot // dot-free paths (standard packages) compare less
		}
		return importI < importJ
	})

	return paths, nil
}

// isDirectlyCyclical checks if imported directly imports pkg.
// It does not (yet) offer a full cyclical check because showing a user
// a list of importable packages already generates a very large list
// and having a few false positives in there could be worth the
// performance snappiness.
//
// TODO(adonovan): ensure that metadata graph is always cyclic!
// Many algorithms will get confused or even stuck in the
// presence of cycles. Then replace this function by 'false'.
func isDirectlyCyclical(pkg, imported *metadata.Package) bool {
	_, ok := imported.DepsByPkgPath[pkg.PkgPath]
	return ok
}


================================================
FILE: gopls/internal/golang/lines.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines refactorings for splitting lists of elements
// (arguments, literals, etc) across multiple lines, and joining
// them into a single line.

import (
	"bytes"
	"go/ast"
	"go/token"
	"slices"
	"sort"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// canSplitLines checks whether we can split lists of elements inside
// an enclosing curly bracket/parens into separate lines.
func canSplitLines(curFile inspector.Cursor, fset *token.FileSet, start, end token.Pos) (string, bool, error) {
	itemType, items, comments, _, _, _ := findSplitJoinTarget(fset, curFile, nil, start, end)
	if itemType == "" {
		return "", false, nil
	}

	if !canSplitJoinLines(items, comments) {
		return "", false, nil
	}

	for i := 1; i < len(items); i++ {
		prevLine := safetoken.EndPosition(fset, items[i-1].End()).Line
		curLine := safetoken.StartPosition(fset, items[i].Pos()).Line
		if prevLine == curLine {
			return "Split " + itemType + " into separate lines", true, nil
		}
	}

	return "", false, nil
}

// canJoinLines checks whether we can join lists of elements inside an
// enclosing curly bracket/parens into a single line.
func canJoinLines(curFile inspector.Cursor, fset *token.FileSet, start, end token.Pos) (string, bool, error) {
	itemType, items, comments, _, _, _ := findSplitJoinTarget(fset, curFile, nil, start, end)
	if itemType == "" {
		return "", false, nil
	}

	if !canSplitJoinLines(items, comments) {
		return "", false, nil
	}

	for i := 1; i < len(items); i++ {
		prevLine := safetoken.EndPosition(fset, items[i-1].End()).Line
		curLine := safetoken.StartPosition(fset, items[i].Pos()).Line
		if prevLine != curLine {
			return "Join " + itemType + " into one line", true, nil
		}
	}

	return "", false, nil
}

// canSplitJoinLines determines whether we should split/join the lines or not.
func canSplitJoinLines(items []ast.Node, comments []*ast.CommentGroup) bool {
	if len(items) <= 1 {
		return false
	}

	for _, cg := range comments {
		if !strings.HasPrefix(cg.List[0].Text, "/*") {
			return false // can't split/join lists containing "//" comments
		}
	}

	return true
}

// splitLines is a singleFile fixer.
func splitLines(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	fset := pkg.FileSet()
	itemType, items, comments, indent, braceOpen, braceClose := findSplitJoinTarget(fset, pgf.Cursor(), pgf.Src, start, end)
	if itemType == "" {
		return nil, nil, nil // no fix available
	}

	return fset, processLines(fset, items, comments, pgf.Src, braceOpen, braceClose, ",\n", "\n", ",\n"+indent, indent+"\t"), nil
}

// joinLines is a singleFile fixer.
func joinLines(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	fset := pkg.FileSet()
	itemType, items, comments, _, braceOpen, braceClose := findSplitJoinTarget(fset, pgf.Cursor(), pgf.Src, start, end)
	if itemType == "" {
		return nil, nil, nil // no fix available
	}

	return fset, processLines(fset, items, comments, pgf.Src, braceOpen, braceClose, ", ", "", "", ""), nil
}

// processLines is the common operation for both split and join lines because this split/join operation is
// essentially a transformation of the separating whitespace.
func processLines(fset *token.FileSet, items []ast.Node, comments []*ast.CommentGroup, src []byte, braceOpen, braceClose token.Pos, sep, prefix, suffix, indent string) *analysis.SuggestedFix {
	nodes := slices.Clone(items)

	// box *ast.CommentGroup to ast.Node for easier processing later.
	for _, cg := range comments {
		nodes = append(nodes, cg)
	}

	// Sort to interleave comments and nodes.
	sort.Slice(nodes, func(i, j int) bool {
		return nodes[i].Pos() < nodes[j].Pos()
	})

	edits := []analysis.TextEdit{
		{
			Pos:     token.Pos(int(braceOpen) + len("{")),
			End:     nodes[0].Pos(),
			NewText: []byte(prefix + indent),
		},
		{
			Pos:     nodes[len(nodes)-1].End(),
			End:     braceClose,
			NewText: []byte(suffix),
		},
	}

	for i := 1; i < len(nodes); i++ {
		pos, end := nodes[i-1].End(), nodes[i].Pos()
		if pos > end {
			// this will happen if we have a /*-style comment inside of a Field
			// e.g. `a /*comment here */ int`
			//
			// we will ignore as we only care about finding the field delimiter.
			continue
		}

		// at this point, the `,` token in between 2 nodes here must be the field delimiter.
		posOffset := safetoken.EndPosition(fset, pos).Offset
		endOffset := safetoken.StartPosition(fset, end).Offset
		if bytes.IndexByte(src[posOffset:endOffset], ',') == -1 {
			// nodes[i] or nodes[i-1] is a comment hence no delimiter in between
			// in such case, do nothing.
			continue
		}

		edits = append(edits, analysis.TextEdit{Pos: pos, End: end, NewText: []byte(sep + indent)})

		// Print the Ellipsis if we synthesized one earlier.
		if is[*ast.Ellipsis](nodes[i]) {
			edits = append(edits, analysis.TextEdit{
				Pos:     nodes[i].End(),
				End:     nodes[i].End(),
				NewText: []byte("..."),
			})
		}
	}

	return &analysis.SuggestedFix{TextEdits: edits}
}

// findSplitJoinTarget returns the first curly bracket/parens that encloses the current cursor.
func findSplitJoinTarget(fset *token.FileSet, curFile inspector.Cursor, src []byte, start, end token.Pos) (itemType string, items []ast.Node, comments []*ast.CommentGroup, indent string, open, close token.Pos) {

	findTarget := func() (targetType string, target ast.Node, open, close token.Pos) {
		cur, _ := curFile.FindByPos(start, end)
		for cur := range cur.Enclosing() {
			// TODO: do cur = enclosingUnparen(cur) first, once CL 701035 lands.
			switch cur.ParentEdgeKind() {
			// params or results of func signature
			// Note:
			// - each ast.Field (e.g. "x, y, z int") is considered a single item.
			// - splitting Params and Results lists is not usually good style.
			case edge.FuncType_Params:
				p := cur.Node().(*ast.FieldList)
				return "parameters", p, p.Opening, p.Closing
			case edge.FuncType_Results:
				r := cur.Node().(*ast.FieldList)
				if !r.Opening.IsValid() {
					continue
				}
				return "results", r, r.Opening, r.Closing
			case edge.CallExpr_Args: // f(a, b, c)
				node := cur.Parent().Node().(*ast.CallExpr)
				return "arguments", node, node.Lparen, node.Rparen
			case edge.CompositeLit_Elts: // T{a, b, c}
				node := cur.Parent().Node().(*ast.CompositeLit)
				return "elements", node, node.Lbrace, node.Rbrace
			}
		}
		return "", nil, 0, 0
	}

	targetType, targetNode, open, close := findTarget()
	if targetType == "" {
		return "", nil, nil, "", 0, 0
	}

	switch node := targetNode.(type) {
	case *ast.FieldList:
		for _, field := range node.List {
			items = append(items, field)
		}
	case *ast.CallExpr:
		for _, arg := range node.Args {
			items = append(items, arg)
		}

		// Preserve "..." by wrapping the last
		// argument in an Ellipsis node
		// with the same Pos/End as the argument.
		// See corresponding logic in processLines.
		if node.Ellipsis.IsValid() {
			last := &items[len(items)-1]
			*last = &ast.Ellipsis{
				Ellipsis: (*last).Pos(),      // determines Ellipsis.Pos()
				Elt:      (*last).(ast.Expr), // determines Ellipsis.End()
			}
		}
	case *ast.CompositeLit:
		for _, arg := range node.Elts {
			items = append(items, arg)
		}
	}

	// preserve comments separately as it's not part of the targetNode AST.
	file := curFile.Node().(*ast.File)
	for _, cg := range file.Comments {
		if open <= cg.Pos() && cg.Pos() < close {
			comments = append(comments, cg)
		}
	}

	// indent is the leading whitespace before the opening curly bracket/paren.
	//
	// in case where we don't have access to src yet i.e. src == nil
	// it's fine to return incorrect indent because we don't need it yet.
	indent = ""
	if len(src) > 0 {
		var pos token.Pos
		switch node := targetNode.(type) {
		case *ast.FieldList:
			pos = node.Opening
		case *ast.CallExpr:
			pos = node.Lparen
		case *ast.CompositeLit:
			pos = node.Lbrace
		}

		split := bytes.Split(src, []byte("\n"))
		targetLineNumber := safetoken.StartPosition(fset, pos).Line
		firstLine := string(split[targetLineNumber-1])
		trimmed := strings.TrimSpace(string(firstLine))
		indent = firstLine[:strings.Index(firstLine, trimmed)]
	}

	return targetType, items, comments, indent, open, close
}


================================================
FILE: gopls/internal/golang/linkname.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"errors"
	"fmt"
	"go/token"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
)

// ErrNoLinkname is returned by LinknameDefinition when no linkname
// directive is found at a particular position.
// As such it indicates that other definitions could be worth checking.
var ErrNoLinkname = errors.New("no linkname directive found")

// linknameDefinition finds the definition of the linkname directive in m at pos.
// If there is no linkname directive at pos, returns ErrNoLinkname.
func linknameDefinition(ctx context.Context, snapshot *cache.Snapshot, m *protocol.Mapper, from protocol.Range) ([]protocol.Location, error) {
	pkgPath, name, _ := parseLinkname(m, from)
	if pkgPath == "" {
		return nil, ErrNoLinkname
	}

	_, pgf, pos, err := findLinkname(ctx, snapshot, PackagePath(pkgPath), name)
	if err != nil {
		return nil, fmt.Errorf("find linkname: %w", err)
	}
	loc, err := pgf.PosLocation(pos, pos+token.Pos(len(name)))
	if err != nil {
		return nil, fmt.Errorf("location of linkname: %w", err)
	}
	return []protocol.Location{loc}, nil
}

// parseLinkname attempts to parse a go:linkname declaration at the given range.
// If successful, it returns
// - package path referenced
// - object name referenced
// - byte offset in mapped file of the start of the link target
// of the linkname directives 2nd argument.
//
// If the range is not in the second argument of a go:linkname directive, or
// parsing fails, it returns "", "", 0.
func parseLinkname(m *protocol.Mapper, rng protocol.Range) (pkgPath, name string, targetOffset int) {
	if rng.Start.Line != rng.End.Line {
		return "", "", 0
	}

	lineStart, err := m.PositionOffset(protocol.Position{Line: rng.Start.Line, Character: 0})
	if err != nil {
		return "", "", 0
	}
	lineEnd, err := m.PositionOffset(protocol.Position{Line: rng.Start.Line + 1, Character: 0})
	if err != nil {
		return "", "", 0
	}

	directive := string(m.Content[lineStart:lineEnd])
	// (Assumes no leading spaces.)
	if !strings.HasPrefix(directive, "//go:linkname") {
		return "", "", 0
	}
	// Sometimes source code (typically tests) has another
	// comment after the directive, trim that away.
	if i := strings.LastIndex(directive, "//"); i != 0 {
		directive = strings.TrimSpace(directive[:i])
	}

	// Looking for pkgpath in '//go:linkname f pkgpath.g'.
	// (We ignore 1-arg linkname directives.)
	parts := strings.Fields(directive)
	if len(parts) != 3 {
		return "", "", 0
	}

	// Inside 2nd arg [start, end]?
	// (Assumes no trailing spaces.)
	startOffset, endOffset, err := m.RangeOffsets(rng)
	if err != nil {
		return "", "", 0
	}
	end := lineStart + len(directive)
	start := end - len(parts[2])
	if !(start <= startOffset && endOffset <= end) {
		return "", "", 0
	}
	linkname := parts[2]

	// Split the pkg path from the name.
	dot := strings.LastIndexByte(linkname, '.')
	if dot < 0 {
		return "", "", 0
	}

	return linkname[:dot], linkname[dot+1:], start
}

// findLinkname searches dependencies of packages containing fh for an object
// with linker name matching the given package path and name.
func findLinkname(ctx context.Context, snapshot *cache.Snapshot, pkgPath PackagePath, name string) (*cache.Package, *parsego.File, token.Pos, error) {
	// Typically the linkname refers to a forward dependency
	// or a reverse dependency, but in general it may refer
	// to any package that is linked with this one.
	var pkgMeta *metadata.Package
	metas, err := snapshot.AllMetadata(ctx)
	if err != nil {
		return nil, nil, token.NoPos, err
	}
	metadata.RemoveIntermediateTestVariants(&metas)
	for _, meta := range metas {
		if meta.PkgPath == pkgPath {
			pkgMeta = meta
			break
		}
	}
	if pkgMeta == nil {
		return nil, nil, token.NoPos, fmt.Errorf("cannot find package %q", pkgPath)
	}

	// When found, type check the desired package (snapshot.TypeCheck in TypecheckFull mode),
	pkgs, err := snapshot.TypeCheck(ctx, pkgMeta.ID)
	if err != nil {
		return nil, nil, token.NoPos, err
	}
	pkg := pkgs[0]

	obj := pkg.Types().Scope().Lookup(name)
	if obj == nil {
		return nil, nil, token.NoPos, fmt.Errorf("package %q does not define %s", pkgPath, name)
	}

	pos := obj.Pos()
	pgf, err := pkg.FileEnclosing(pos)
	return pkg, pgf, pos, err
}


================================================
FILE: gopls/internal/golang/modify_tags.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/format"

	"github.com/fatih/gomodifytags/modifytags"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	internalastutil "golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/diff"
)

// ModifyTags applies the given struct tag modifications to the specified struct.
func ModifyTags(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, args command.ModifyTagsArgs, m *modifytags.Modification) ([]protocol.DocumentChange, error) {
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, fmt.Errorf("error fetching package file: %v", err)
	}
	start, end, err := pgf.RangePos(args.Range)
	if err != nil {
		return nil, fmt.Errorf("error getting position information: %v", err)
	}
	// If the cursor is at a point and not a selection, we should use the entire enclosing struct.
	if start == end {
		cur, ok := pgf.Cursor().FindByPos(start, end)
		if !ok {
			return nil, fmt.Errorf("error finding start and end positions: %v", err)
		}
		structnode, _ := cursorutil.FirstEnclosing[*ast.StructType](cur)
		if structnode == nil {
			return nil, fmt.Errorf("no enclosing struct type")
		}
		start, end = structnode.Pos(), structnode.End()
	}

	// Create a copy of the file node in order to avoid race conditions when we modify the node in Apply.
	cloned := internalastutil.CloneNode(pgf.File)
	fset := tokeninternal.FileSetFor(pgf.Tok)

	if err = m.Apply(fset, cloned, start, end); err != nil {
		return nil, fmt.Errorf("could not modify tags: %v", err)
	}

	// Construct a list of DocumentChanges based on the diff between the formatted node and the
	// original file content.
	var after bytes.Buffer
	if err := format.Node(&after, fset, cloned); err != nil {
		return nil, err
	}
	edits := diff.Bytes(pgf.Src, after.Bytes())
	if len(edits) == 0 {
		return nil, nil
	}
	textedits, err := protocol.EditsFromDiffEdits(pgf.Mapper, edits)
	if err != nil {
		return nil, fmt.Errorf("error computing edits for %s: %v", args.URI, err)
	}
	return []protocol.DocumentChange{
		protocol.DocumentChangeEdit(fh, textedits),
	}, nil
}


================================================
FILE: gopls/internal/golang/movetype.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/moreiters"
)

// MoveType moves the selected type declaration into a new package and updates all references.
func MoveType(ctx context.Context, fh file.Handle, snapshot *cache.Snapshot, loc protocol.Location, newPkgDir string) ([]protocol.DocumentChange, error) {
	return nil, fmt.Errorf("MoveType: not yet supported")
}

// selectionContainsType returns the Cursor, GenDecl and TypeSpec of the type
// declaration that encloses cursor if one exists. Otherwise it returns false.
func selectionContainsType(cursor inspector.Cursor) (inspector.Cursor, *ast.GenDecl, *ast.TypeSpec, string, bool) {
	declCur, ok := moreiters.First(cursor.Enclosing((*ast.GenDecl)(nil)))
	if !ok {
		return inspector.Cursor{}, &ast.GenDecl{}, &ast.TypeSpec{}, "", false
	}

	// Verify that we have a type declaration (e.g. not an import declaration).
	declNode := declCur.Node().(*ast.GenDecl)
	if declNode.Tok != token.TYPE {
		return inspector.Cursor{}, &ast.GenDecl{}, &ast.TypeSpec{}, "", false
	}

	typSpec, ok := declNode.Specs[0].(*ast.TypeSpec)
	if !ok {
		return inspector.Cursor{}, &ast.GenDecl{}, &ast.TypeSpec{}, "", false
	}

	return declCur, declNode, declNode.Specs[0].(*ast.TypeSpec), typSpec.Name.Name, true
}


================================================
FILE: gopls/internal/golang/origin.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import "go/types"

// containsOrigin reports whether the provided object set contains an object
// with the same origin as the provided obj (which may be a synthetic object
// created during instantiation).
func containsOrigin(objSet map[types.Object]bool, obj types.Object) bool {
	objOrigin := origin(obj)
	for target := range objSet {
		if origin(target) == objOrigin {
			return true
		}
	}
	return false
}

func origin(obj types.Object) types.Object {
	switch obj := obj.(type) {
	case *types.Var:
		return obj.Origin()
	case *types.Func:
		return obj.Origin()
	}
	return obj
}


================================================
FILE: gopls/internal/golang/pkgdoc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines a simple HTML rendering of package documentation
// in imitation of the style of pkg.go.dev.
//
// The current implementation is just a starting point and a
// placeholder for a more sophisticated one.
//
// TODO(adonovan):
// - rewrite using html/template.
//   Or factor with golang.org/x/pkgsite/internal/godoc/dochtml.
// - emit breadcrumbs for parent + sibling packages.
// - list promoted methods---we have type information! (golang/go#67158)
// - gather Example tests, following go/doc and pkgsite.
// - add option for doc.AllDecls: show non-exported symbols too.
// - style the <li> bullets in the index as invisible.
// - add push notifications such as didChange -> reload.
// - there appears to be a maximum file size beyond which the
//   "source.doc" code action is not offered. Remove that.
// - modify JS httpGET function to give a transient visual indication
//   when clicking a source link that the editor is being navigated
//   (in case it doesn't raise itself, like VS Code).
// - move this into a new package, golang/web, and then
//   split out the various helpers without fear of polluting
//   the golang package namespace?
// - show "Deprecated" chip when appropriate.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/doc"
	"go/doc/comment"
	"go/format"
	"go/token"
	"go/types"
	"html"
	"path/filepath"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/typesinternal"
)

// DocFragment finds the package and (optionally) symbol identified by
// the current selection, and returns the package path and the
// optional symbol URL fragment (e.g. "#Buffer.Len") for a symbol,
// along with a title for the code action.
//
// It is called once to offer the code action, and again when the
// command is executed. This is slightly inefficient but ensures that
// the title and package/symbol logic are consistent in all cases.
//
// It returns zeroes if there is nothing to see here (e.g. reference to a builtin).
func DocFragment(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (pkgpath PackagePath, fragment, title string) {
	thing := thingAtPoint(pkg, pgf, start, end)

	makeTitle := func(kind string, imp *types.Package, name string) string {
		title := "Browse documentation for " + kind + " "
		if imp != nil && imp != pkg.Types() {
			title += imp.Name() + "."
		}
		return title + name
	}

	wholePackage := func(pkg *types.Package) (PackagePath, string, string) {
		// External test packages don't have /pkg doc pages,
		// so instead show the doc for the package under test.
		// (This named-based heuristic is imperfect.)
		if forTest, ok := strings.CutSuffix(pkg.Path(), "_test"); ok {
			return PackagePath(forTest), "", makeTitle("package", nil, filepath.Base(forTest))
		}

		return PackagePath(pkg.Path()), "", makeTitle("package", nil, pkg.Name())
	}

	// Conceptually, we check cases in the order:
	// 1. symbol
	// 2. package
	// 3. enclosing
	// but the logic of cases 1 and 3 are identical, hence the odd factoring.

	// Imported package?
	if thing.pkg != nil && thing.symbol == nil {
		return wholePackage(thing.pkg)
	}

	// Symbol?
	var sym types.Object
	if thing.symbol != nil {
		sym = thing.symbol // reference to a symbol
	} else if thing.enclosing != nil {
		sym = thing.enclosing // selection is within a declaration of a symbol
	}
	if sym == nil {
		return wholePackage(pkg.Types()) // no symbol
	}

	// Built-in (error.Error, append or unsafe).
	// TODO(adonovan): handle builtins in /pkg viewer.
	if sym.Pkg() == nil {
		return "", "", "" // nothing to see here
	}
	pkgpath = PackagePath(sym.Pkg().Path())

	// Unexported? Show enclosing type or package.
	if !sym.Exported() {
		// Unexported method of exported type?
		if fn, ok := sym.(*types.Func); ok {
			if recv := fn.Signature().Recv(); recv != nil {
				_, named := typesinternal.ReceiverNamed(recv)
				if named != nil && named.Obj().Exported() {
					sym = named.Obj()
					goto below
				}
			}
		}

		return wholePackage(sym.Pkg())
	below:
	}

	// Reference to symbol in external test package?
	// Short-circuit: see comment in wholePackage.
	if strings.HasSuffix(string(pkgpath), "_test") {
		return wholePackage(pkg.Types())
	}

	// package-level symbol?
	if typesinternal.IsPackageLevel(sym) {
		return pkgpath, sym.Name(), makeTitle(objectKind(sym), sym.Pkg(), sym.Name())
	}

	// Inv: sym is field or method, or local.
	switch sym := sym.(type) {
	case *types.Func: // => method
		sig := sym.Signature()
		isPtr, named := typesinternal.ReceiverNamed(sig.Recv())
		if named != nil {
			if !named.Obj().Exported() {
				return wholePackage(sym.Pkg()) // exported method of unexported type
			}
			name := fmt.Sprintf("(%s%s).%s",
				strings.Repeat("*", btoi(isPtr)), // for *T
				named.Obj().Name(),
				sym.Name())
			fragment := named.Obj().Name() + "." + sym.Name()
			return pkgpath, fragment, makeTitle("method", sym.Pkg(), name)
		}

	case *types.Var:
		if sym.IsField() {
			// TODO(adonovan): support fields.
			// The Var symbol doesn't include the struct
			// type, so we need to use the logic from
			// Hover. (This isn't important for
			// DocFragment as fields don't have fragments,
			// but it matters to the grand unification of
			// Hover/Definition/DocFragment.
		}
	}

	// Field, non-exported method, or local declaration:
	// just show current package.
	return wholePackage(pkg.Types())
}

// thing describes the package or symbol denoted by a selection.
//
// TODO(adonovan): Hover, Definition, and References all start by
// identifying the selected object. Let's achieve a better factoring
// of the common parts using this structure, including uniform
// treatment of doc links, linkname, and suchlike.
type thing struct {
	// At most one of these fields is set.
	// (The 'enclosing' field is a fallback for when neither
	// of the first two is set.)
	symbol    types.Object   // referenced symbol
	pkg       *types.Package // referenced package
	enclosing types.Object   // package-level symbol or method decl enclosing selection
}

func thingAtPoint(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) thing {
	cur, _, _, _ := astutil.Select(pgf.Cursor(), start, end)

	// In an import spec?
	if spec, _ := cursorutil.FirstEnclosing[*ast.ImportSpec](cur); spec != nil {
		if pkgname := pkg.TypesInfo().PkgNameOf(spec); pkgname != nil {
			return thing{pkg: pkgname.Imported()}
		}
	}

	// Definition or reference to symbol?
	var obj types.Object
	if id, ok := cur.Node().(*ast.Ident); ok {
		obj = pkg.TypesInfo().ObjectOf(id)

		// Treat use to PkgName like ImportSpec.
		if pkgname, ok := obj.(*types.PkgName); ok {
			return thing{pkg: pkgname.Imported()}
		}

	} else if sel, ok := cur.Node().(*ast.SelectorExpr); ok {
		// e.g. selection is "fmt.Println" or just a portion ("mt.Prin")
		obj = pkg.TypesInfo().Uses[sel.Sel]
	}
	if obj != nil {
		return thing{symbol: obj}
	}

	// Find outermost enclosing declaration.
	var id *ast.Ident
	for cur := range cur.Enclosing((*ast.FuncDecl)(nil), (*ast.ValueSpec)(nil), (*ast.TypeSpec)(nil)) {
		switch n := cur.Node().(type) {
		case *ast.FuncDecl: // function or method
			id = n.Name
		case *ast.ValueSpec:
			id = n.Names[0] // var, const: use first name
		case *ast.TypeSpec:
			id = n.Name
		}
	}
	if obj := pkg.TypesInfo().Defs[id]; obj != nil {
		return thing{enclosing: obj}
	}

	return thing{} // nothing to see here
}

// Web is an abstraction of gopls' web server.
type Web interface {
	// PkgURL forms URLs of package or symbol documentation.
	PkgURL(viewID string, path PackagePath, fragment string) protocol.URI

	// SrcURL forms URLs that cause the editor to open a file at a specific position.
	SrcURL(filename string, line, col8 int) protocol.URI
}

// PackageDocHTML formats the package documentation page.
//
// The posURL function returns a URL that when visited, has the side
// effect of causing gopls to direct the client editor to navigate to
// the specified file/line/column position, in UTF-8 coordinates.
//
// TODO(adonovan): this function could use some unit tests; we
// shouldn't have to use integration tests to cover microdetails of
// HTML rendering. (It is tempting to abstract this function so that
// it depends only on FileSet/File/Types/TypeInfo/etc, but we should
// bend the tests to the production interfaces, not the other way
// around.)
func PackageDocHTML(viewID string, pkg *cache.Package, web Web) ([]byte, error) {
	// We can't use doc.NewFromFiles (even with doc.PreserveAST
	// mode) as it calls ast.NewPackage which assumes that each
	// ast.File has an ast.Scope and resolves identifiers to
	// (deprecated) ast.Objects. (This is golang/go#66290.)
	// But doc.New only requires pkg.{Name,Files},
	// so we just boil it down.
	//
	// The only loss is doc.classifyExamples.
	// TODO(adonovan): simulate that too.
	fileMap := make(map[string]*ast.File)
	for _, f := range pkg.Syntax() {
		fileMap[pkg.FileSet().File(f.FileStart).Name()] = f
	}
	astpkg := &ast.Package{
		Name:  pkg.Types().Name(),
		Files: fileMap,
	}
	// PreserveAST mode only half works (golang/go#66449): it still
	// mutates ASTs when filtering out non-exported symbols.
	// As a workaround, enable AllDecls to suppress filtering,
	// and do it ourselves.
	mode := doc.PreserveAST | doc.AllDecls
	docpkg := doc.New(astpkg, pkg.Types().Path(), mode)

	// Discard non-exported symbols.
	// TODO(adonovan): do this conditionally, and expose option in UI.
	const showUnexported = false
	if !showUnexported {
		var (
			unexported   = func(name string) bool { return !token.IsExported(name) }
			filterValues = func(slice *[]*doc.Value) {
				delValue := func(v *doc.Value) bool {
					v.Names = slices.DeleteFunc(v.Names, unexported)
					return len(v.Names) == 0
				}
				*slice = slices.DeleteFunc(*slice, delValue)
			}
			filterFuncs = func(funcs *[]*doc.Func) {
				*funcs = slices.DeleteFunc(*funcs, func(v *doc.Func) bool {
					return unexported(v.Name)
				})
			}
		)
		filterValues(&docpkg.Consts)
		filterValues(&docpkg.Vars)
		filterFuncs(&docpkg.Funcs)
		docpkg.Types = slices.DeleteFunc(docpkg.Types, func(t *doc.Type) bool {
			filterValues(&t.Consts)
			filterValues(&t.Vars)
			filterFuncs(&t.Funcs)
			filterFuncs(&t.Methods)
			if unexported(t.Name) {
				// If an unexported type has an exported constructor function,
				// treat the constructor as an ordinary standalone function.
				// We will sort Funcs again below.
				docpkg.Funcs = append(docpkg.Funcs, t.Funcs...)
				return true // delete this type
			}
			return false // keep this type
		})
		slices.SortFunc(docpkg.Funcs, func(x, y *doc.Func) int {
			return strings.Compare(x.Name, y.Name)
		})
	}

	// docHTML renders the doc comment as Markdown.
	// The fileNode is used to deduce the enclosing file
	// for the correct import mapping.
	//
	// It is not concurrency-safe.
	var docHTML func(fileNode ast.Node, comment string) []byte
	{
		// Adapt doc comment parser and printer
		// to our representation of Go packages
		// so that doc links (e.g. "[fmt.Println]")
		// become valid links.
		printer := &comment.Printer{
			DocLinkURL: func(link *comment.DocLink) string {
				path := pkg.Metadata().PkgPath
				if link.ImportPath != "" {
					path = PackagePath(link.ImportPath)
				}
				fragment := link.Name
				if link.Recv != "" {
					fragment = link.Recv + "." + link.Name
				}
				return web.PkgURL(viewID, path, fragment)
			},
		}
		parse := newDocCommentParser(pkg)
		docHTML = func(fileNode ast.Node, comment string) []byte {
			doc := parse(fileNode, comment)
			return printer.HTML(doc)
		}
	}

	scope := pkg.Types().Scope()
	escape := html.EscapeString

	title := fmt.Sprintf("%s package - %s - Gopls packages",
		pkg.Types().Name(), escape(pkg.Types().Path()))

	var buf bytes.Buffer
	buf.WriteString(`<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>` + title + `</title>
  <link rel="stylesheet" href="/assets/common.css">
  <script src="/assets/common.js"></script>
  <style>
.lit { color: darkgreen; }

header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  padding: 0.3em;
}

.Documentation-sinceVersion {
  font-weight: normal;
  color: #808080;
  float: right;
}

#pkgsite { height: 1.5em; }

#hdr-Selector {
  margin-right: 0.3em;
  float: right;
  min-width: 25em;
  padding: 0.3em;
}
  </style>
  <script type='text/javascript'>
window.addEventListener('load', function() {
	// Hook up the navigation selector.
	document.getElementById('hdr-Selector').onchange = (e) => {
		window.location.href = e.target.value;
	};
});
  </script>
</head>
<body>
<header>
<select id='hdr-Selector'>
<optgroup label="Documentation">
  <option label="Overview" value="#hdr-Overview"/>
  <option label="Index" value="#hdr-Index"/>
  <option label="Constants" value="#hdr-Constants"/>
  <option label="Variables" value="#hdr-Variables"/>
  <option label="Functions" value="#hdr-Functions"/>
  <option label="Types" value="#hdr-Types"/>
  <option label="Source Files" value="#hdr-SourceFiles"/>
</optgroup>
`)

	// -- header select element --

	// option emits an <option> for the specified symbol.
	//
	// recvType is the apparent receiver type, which may
	// differ from ReceiverNamed(obj.Signature.Recv).Name
	// for promoted methods.
	option := func(obj types.Object, recvType string) {
		// Render functions/methods as "(recv) Method(p1, ..., pN)".
		fragment := obj.Name()

		// format parameter names (p1, ..., pN)
		label := obj.Name() // for a type
		if fn, ok := obj.(*types.Func); ok {
			var buf strings.Builder
			sig := fn.Signature()
			if sig.Recv() != nil {
				fmt.Fprintf(&buf, "(%s) ", sig.Recv().Name())
				fragment = recvType + "." + fn.Name()
			}
			fmt.Fprintf(&buf, "%s(", fn.Name())
			for i := 0; i < sig.Params().Len(); i++ {
				if i > 0 {
					buf.WriteString(", ")
				}
				name := sig.Params().At(i).Name()
				if name == "" {
					name = "_"
				}
				buf.WriteString(name)
			}
			buf.WriteByte(')')
			label = buf.String()
		}

		fmt.Fprintf(&buf, "  <option label='%s' value='#%s'/>\n", label, fragment)
	}

	// index of functions
	fmt.Fprintf(&buf, "<optgroup label='Functions'>\n")
	for _, fn := range docpkg.Funcs {
		option(scope.Lookup(fn.Name), "")
	}
	fmt.Fprintf(&buf, "</optgroup>\n")

	// index of types
	fmt.Fprintf(&buf, "<optgroup label='Types'>\n")
	for _, doctype := range docpkg.Types {
		option(scope.Lookup(doctype.Name), "")
	}
	fmt.Fprintf(&buf, "</optgroup>\n")

	// index of constructors and methods of each type
	for _, doctype := range docpkg.Types {
		tname := scope.Lookup(doctype.Name).(*types.TypeName)
		if len(doctype.Funcs)+len(doctype.Methods) > 0 {
			fmt.Fprintf(&buf, "<optgroup label='type %s'>\n", doctype.Name)
			for _, docfn := range doctype.Funcs {
				option(scope.Lookup(docfn.Name), "")
			}
			for _, docmethod := range doctype.Methods {
				method, _, _ := types.LookupFieldOrMethod(tname.Type(), true, tname.Pkg(), docmethod.Name)
				option(method, doctype.Name)
			}
			fmt.Fprintf(&buf, "</optgroup>\n")
		}
	}
	fmt.Fprintf(&buf, "</select>\n")
	fmt.Fprintf(&buf, "</header>\n")

	// -- main element --

	// nodeHTML returns HTML markup for a syntax tree.
	// It replaces referring identifiers with links,
	// and adds style spans for strings and comments.
	nodeHTML := func(n ast.Node) string {

		// linkify returns the appropriate URL (if any) for an identifier.
		linkify := func(id *ast.Ident) protocol.URI {
			if obj, ok := pkg.TypesInfo().Uses[id]; ok && obj.Pkg() != nil {
				// imported package name?
				if pkgname, ok := obj.(*types.PkgName); ok {
					// TODO(adonovan): do this for Defs of PkgName too.
					return web.PkgURL(viewID, PackagePath(pkgname.Imported().Path()), "")
				}

				// package-level symbol?
				if obj.Parent() == obj.Pkg().Scope() {
					if obj.Pkg() == pkg.Types() {
						return "#" + obj.Name() // intra-package ref
					} else {
						return web.PkgURL(viewID, PackagePath(obj.Pkg().Path()), obj.Name())
					}
				}

				// method of package-level named type?
				if fn, ok := obj.(*types.Func); ok {
					sig := fn.Signature()
					if sig.Recv() != nil {
						_, named := typesinternal.ReceiverNamed(sig.Recv())
						if named != nil {
							fragment := named.Obj().Name() + "." + fn.Name()
							return web.PkgURL(viewID, PackagePath(fn.Pkg().Path()), fragment)
						}
					}
					return ""
				}

				// TODO(adonovan): field of package-level named struct type.
				// (Requires an index, since there's no way to
				// get from Var to Named.)
			}
			return ""
		}

		// Splice spans into HTML-escaped segments of the
		// original source buffer (which is usually but not
		// necessarily formatted).
		//
		// (For expedience we don't use the more sophisticated
		// approach taken by cmd/godoc and pkgsite's render
		// package, which emit the text, spans, and comments
		// in one traversal of the syntax tree.)
		//
		// TODO(adonovan): splice styled spans around comments too.
		//
		// TODO(adonovan): pkgsite prints specs from grouped
		// type decls like "type ( T1; T2 )" to make them
		// appear as separate decls. We should too.
		var buf bytes.Buffer
		for _, file := range pkg.CompiledGoFiles() {
			if astutil.NodeContainsPos(file.File, n.Pos()) {
				pos := n.Pos()

				// emit emits source in the interval [pos:to] and updates pos.
				emit := func(to token.Pos) {
					// Ident and BasicLit always have a valid pos.
					// (Failure means the AST has been corrupted.)
					if !to.IsValid() {
						bug.Reportf("invalid Pos")
					}
					text, err := file.PosText(pos, to)
					if err != nil {
						bug.Reportf("invalid pos range: %v", err)
						return
					}
					buf.WriteString(escape(string(text)))
					pos = to
				}
				ast.Inspect(n, func(n ast.Node) bool {
					switch n := n.(type) {
					case *ast.Ident:
						emit(n.Pos())
						pos = n.End()
						if url := linkify(n); url != "" {
							fmt.Fprintf(&buf, "<a class='id' href='%s'>%s</a>", url, escape(n.Name))
						} else {
							buf.WriteString(escape(n.Name)) // plain
						}

					case *ast.BasicLit:
						emit(n.Pos())
						pos = n.End()
						fmt.Fprintf(&buf, "<span class='lit'>%s</span>", escape(n.Value))
					}
					return true
				})
				emit(n.End())
				return buf.String()
			}
		}

		// Original source not found.
		// Format the node without adornments.
		if err := format.Node(&buf, pkg.FileSet(), n); err != nil {
			// e.g. BadDecl?
			buf.Reset()
			fmt.Fprintf(&buf, "formatting error: %v", err)
		}
		return escape(buf.String())
	}

	// fnString is like fn.String() except that it:
	// - shows the receiver name;
	// - uses space "(T) M()" not dot "(T).M()" after receiver;
	// - doesn't bother with the special case for interface receivers
	//   since it is unreachable for the methods in go/doc.
	// - elides parameters after the first three: f(a, b, c, ...).
	fnString := func(fn *types.Func) string {
		pkgRelative := typesinternal.NameRelativeTo(pkg.Types())

		sig := fn.Signature()

		// Emit "func (recv T) F".
		var buf bytes.Buffer
		buf.WriteString("func ")
		if recv := sig.Recv(); recv != nil {
			buf.WriteByte('(')
			if recv.Name() != "" {
				buf.WriteString(recv.Name())
				buf.WriteByte(' ')
			}
			types.WriteType(&buf, recv.Type(), pkgRelative)
			buf.WriteByte(')')
			buf.WriteByte(' ') // (ObjectString uses a '.' here)
		} else if pkg := fn.Pkg(); pkg != nil {
			if s := pkgRelative(pkg); s != "" {
				buf.WriteString(s)
				buf.WriteByte('.')
			}
		}
		buf.WriteString(fn.Name())

		// Emit signature.
		//
		// Elide parameters after the third one.
		// WriteSignature is too complex to fork, so we replace
		// parameters 4+ with "invalid type", format,
		// then post-process the string.
		if sig.Params().Len() > 3 {

			// Clone each TypeParam as NewSignatureType modifies them (#67294).
			cloneTparams := func(seq *types.TypeParamList) []*types.TypeParam {
				slice := make([]*types.TypeParam, seq.Len())
				for i := range slice {
					tparam := seq.At(i)
					slice[i] = types.NewTypeParam(tparam.Obj(), tparam.Constraint())
				}
				return slice
			}

			sig = types.NewSignatureType(
				sig.Recv(),
				cloneTparams(sig.RecvTypeParams()),
				cloneTparams(sig.TypeParams()),
				types.NewTuple(append(
					slices.Collect(sig.Params().Variables())[:3],
					types.NewParam(0, nil, "", types.Typ[types.Invalid]))...),
				sig.Results(),
				false) // any final ...T parameter is truncated
		}
		types.WriteSignature(&buf, sig, pkgRelative)
		return strings.ReplaceAll(buf.String(), ", invalid type)", ", ...)")
	}

	fmt.Fprintf(&buf, "<main>\n")

	// package name
	fmt.Fprintf(&buf, "<h1 id='hdr-Overview'>Package %s</h1>\n", pkg.Types().Name())

	// import path
	fmt.Fprintf(&buf, "<pre class='code'>import %q</pre>\n", pkg.Types().Path())

	// link to same package in pkg.go.dev
	fmt.Fprintf(&buf, "<div><a href=%q title='View in pkg.go.dev'><img id='pkgsite' src='/assets/go-logo-blue.svg'/></a>\n",
		"https://pkg.go.dev/"+string(pkg.Types().Path()))

	// package doc
	for _, f := range pkg.Syntax() {
		if f.Doc != nil {
			fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n", docHTML(f.Doc, docpkg.Doc))
			break
		}
	}

	// symbol index
	fmt.Fprintf(&buf, "<h2 id='hdr-Index'>Index</h2>\n")
	fmt.Fprintf(&buf, "<ul>\n")
	if len(docpkg.Consts) > 0 {
		fmt.Fprintf(&buf, "<li><a href='#hdr-Constants'>Constants</a></li>\n")
	}
	if len(docpkg.Vars) > 0 {
		fmt.Fprintf(&buf, "<li><a href='#hdr-Variables'>Variables</a></li>\n")
	}
	for _, fn := range docpkg.Funcs {
		obj := scope.Lookup(fn.Name).(*types.Func)
		fmt.Fprintf(&buf, "<li><a href='#%s'>%s</a></li>\n",
			obj.Name(), escape(fnString(obj)))
	}
	for _, doctype := range docpkg.Types {
		tname := scope.Lookup(doctype.Name).(*types.TypeName)
		fmt.Fprintf(&buf, "<li><a href='#%[1]s'>type %[1]s</a></li>\n",
			tname.Name())

		if len(doctype.Funcs)+len(doctype.Methods) > 0 {
			fmt.Fprintf(&buf, "<ul>\n")

			// constructors
			for _, docfn := range doctype.Funcs {
				obj := scope.Lookup(docfn.Name).(*types.Func)
				fmt.Fprintf(&buf, "<li><a href='#%s'>%s</a></li>\n",
					docfn.Name, escape(fnString(obj)))
			}
			// methods
			for _, docmethod := range doctype.Methods {
				method, _, _ := types.LookupFieldOrMethod(tname.Type(), true, tname.Pkg(), docmethod.Name)
				fmt.Fprintf(&buf, "<li><a href='#%s.%s'>%s</a></li>\n",
					doctype.Name,
					docmethod.Name,
					escape(fnString(method.(*types.Func))))
			}
			fmt.Fprintf(&buf, "</ul>\n")
		}
	}
	// TODO(adonovan): add index of Examples here.
	fmt.Fprintf(&buf, "</ul>\n")

	// constants and variables
	values := func(vals []*doc.Value) {
		for _, v := range vals {
			// anchors
			for _, name := range v.Names {
				fmt.Fprintf(&buf, "<a id='%s'></a>\n", escape(name))
			}

			// declaration
			decl2 := *v.Decl // shallow copy
			decl2.Doc = nil
			fmt.Fprintf(&buf, "<pre class='code'>%s</pre>\n", nodeHTML(&decl2))

			// comment (if any)
			fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n", docHTML(v.Decl, v.Doc))
		}
	}
	fmt.Fprintf(&buf, "<h2 id='hdr-Constants'>Constants</h2>\n")
	if len(docpkg.Consts) == 0 {
		fmt.Fprintf(&buf, "<div>(no constants)</div>\n")
	} else {
		values(docpkg.Consts)
	}
	fmt.Fprintf(&buf, "<h2 id='hdr-Variables'>Variables</h2>\n")
	if len(docpkg.Vars) == 0 {
		fmt.Fprintf(&buf, "<div>(no variables)</div>\n")
	} else {
		values(docpkg.Vars)
	}

	// addedInHTML returns an HTML division containing the Go release version at
	// which this obj became available.
	addedInHTML := func(obj types.Object) string {
		if sym := StdSymbolOf(obj); sym != nil && sym.Version != stdlib.Version(0) {
			return fmt.Sprintf("<span class='Documentation-sinceVersion'>added in %v</span>", sym.Version)
		}
		return ""
	}

	// package-level functions
	fmt.Fprintf(&buf, "<h2 id='hdr-Functions'>Functions</h2>\n")
	// funcs emits a list of package-level functions,
	// possibly organized beneath the type they construct.
	funcs := func(funcs []*doc.Func) {
		for _, docfn := range funcs {
			obj := scope.Lookup(docfn.Name).(*types.Func)

			fmt.Fprintf(&buf, "<h3 id='%s'>func %s %s</h3>\n",
				docfn.Name, objHTML(pkg.FileSet(), web, obj), addedInHTML(obj))

			// decl: func F(params) results
			fmt.Fprintf(&buf, "<pre class='code'>%s</pre>\n",
				nodeHTML(docfn.Decl.Type))

			// comment (if any)
			fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n", docHTML(docfn.Decl, docfn.Doc))
		}
	}
	funcs(docpkg.Funcs)

	// types and their subelements
	fmt.Fprintf(&buf, "<h2 id='hdr-Types'>Types</h2>\n")
	for _, doctype := range docpkg.Types {
		tname := scope.Lookup(doctype.Name).(*types.TypeName)

		// title and source link
		fmt.Fprintf(&buf, "<h3 id='%s'>type %s %s</h3>\n",
			doctype.Name, objHTML(pkg.FileSet(), web, tname), addedInHTML(tname))

		// declaration
		// TODO(adonovan): excise non-exported struct fields somehow.
		decl2 := *doctype.Decl // shallow copy
		decl2.Doc = nil
		fmt.Fprintf(&buf, "<pre class='code'>%s</pre>\n", nodeHTML(&decl2))

		// comment (if any)
		fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n", docHTML(doctype.Decl, doctype.Doc))

		// subelements
		values(doctype.Consts) // constants of type T
		values(doctype.Vars)   // vars of type T
		funcs(doctype.Funcs)   // constructors of T

		// methods on T
		for _, docmethod := range doctype.Methods {
			method, _, _ := types.LookupFieldOrMethod(tname.Type(), true, tname.Pkg(), docmethod.Name)
			fmt.Fprintf(&buf, "<h4 id='%s.%s'>func (%s) %s %s</h4>\n",
				doctype.Name, docmethod.Name,
				docmethod.Orig, // T or *T
				objHTML(pkg.FileSet(), web, method), addedInHTML(method))

			// decl: func (x T) M(params) results
			fmt.Fprintf(&buf, "<pre class='code'>%s</pre>\n",
				nodeHTML(docmethod.Decl.Type))

			// comment (if any)
			fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n",
				docHTML(docmethod.Decl, docmethod.Doc))
		}
	}

	// source files
	fmt.Fprintf(&buf, "<h2 id='hdr-SourceFiles'>Source files</h2>\n")
	for _, filename := range docpkg.Filenames {
		fmt.Fprintf(&buf, "<div class='comment'>%s</div>\n",
			sourceLink(filepath.Base(filename), web.SrcURL(filename, 1, 1)))
	}

	fmt.Fprintf(&buf, "</main>\n")
	fmt.Fprintf(&buf, "</body>\n")
	fmt.Fprintf(&buf, "</html>\n")

	return buf.Bytes(), nil
}


================================================
FILE: gopls/internal/golang/references.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines the 'references' query based on a serializable
// index constructed during type checking, thus avoiding the need to
// type-check packages at search time.
//
// See the ./xrefs/ subpackage for the index construction and lookup.
//
// This implementation does not intermingle objects from distinct
// calls to TypeCheck.

import (
	"context"
	"fmt"
	"go/ast"
	"go/types"
	"sort"
	"strings"
	"sync"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/methodsets"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"

	"golang.org/x/tools/internal/event"
)

// References returns a list of all references (sorted with
// definitions before uses) to the object denoted by the identifier at
// the given file/position, searching the entire workspace.
func References(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range, includeDeclaration bool) ([]protocol.Location, error) {
	references, err := references(ctx, snapshot, fh, rng, includeDeclaration)
	if err != nil {
		return nil, err
	}
	locations := make([]protocol.Location, len(references))
	for i, ref := range references {
		locations[i] = ref.location
	}
	return locations, nil
}

// A reference describes an identifier that refers to the same
// object as the subject of a References query.
type reference struct {
	isDeclaration bool
	location      protocol.Location
	pkgPath       PackagePath // of declaring package (same for all elements of the slice)
}

// references returns a list of all references (sorted with
// definitions before uses) to the object denoted by the identifier at
// the given file/position, searching the entire workspace.
func references(ctx context.Context, snapshot *cache.Snapshot, f file.Handle, rng protocol.Range, includeDeclaration bool) ([]reference, error) {
	ctx, done := event.Start(ctx, "golang.references")
	defer done()

	// Is the cursor within the package name declaration?
	_, inPackageName, err := parsePackageNameDecl(ctx, snapshot, f, rng)
	if err != nil {
		return nil, err
	}

	var refs []reference
	if inPackageName {
		refs, err = packageReferences(ctx, snapshot, f.URI())
	} else {
		refs, err = ordinaryReferences(ctx, snapshot, f.URI(), rng)
	}
	if err != nil {
		return nil, err
	}

	sort.Slice(refs, func(i, j int) bool {
		x, y := refs[i], refs[j]
		if x.isDeclaration != y.isDeclaration {
			return x.isDeclaration // decls < refs
		}
		return protocol.CompareLocation(x.location, y.location) < 0
	})

	// De-duplicate by location, and optionally remove declarations.
	out := refs[:0]
	for _, ref := range refs {
		if !includeDeclaration && ref.isDeclaration {
			continue
		}
		if len(out) == 0 || out[len(out)-1].location != ref.location {
			out = append(out, ref)
		}
	}
	refs = out

	return refs, nil
}

// packageReferences returns a list of references to the package
// declaration of the specified name and uri by searching among the
// import declarations of all packages that directly import the target
// package.
func packageReferences(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) ([]reference, error) {
	metas, err := snapshot.MetadataForFile(ctx, uri, false)
	if err != nil {
		return nil, err
	}
	if len(metas) == 0 {
		return nil, fmt.Errorf("found no package containing %s", uri)
	}

	var refs []reference

	// Find external references to the package declaration
	// from each direct import of the package.
	//
	// The narrowest package is the most broadly imported,
	// so we choose it for the external references.
	//
	// But if the file ends with _test.go then we need to
	// find the package it is testing; there's no direct way
	// to do that, so pick a file from the same package that
	// doesn't end in _test.go and start over.
	narrowest := metas[0]
	if narrowest.ForTest != "" && strings.HasSuffix(string(uri), "_test.go") {
		for _, f := range narrowest.CompiledGoFiles {
			if !strings.HasSuffix(string(f), "_test.go") {
				return packageReferences(ctx, snapshot, f)
			}
		}
		// This package has no non-test files.
		// Skip the search for external references.
		// (Conceivably one could blank-import an empty package, but why?)
	} else {
		rdeps, err := snapshot.ReverseDependencies(ctx, narrowest.ID, false) // direct
		if err != nil {
			return nil, err
		}

		// Restrict search to workspace packages.
		workspace, err := snapshot.WorkspaceMetadata(ctx)
		if err != nil {
			return nil, err
		}
		workspaceMap := make(map[PackageID]*metadata.Package, len(workspace))
		for _, mp := range workspace {
			workspaceMap[mp.ID] = mp
		}

		for _, rdep := range rdeps {
			if _, ok := workspaceMap[rdep.ID]; !ok {
				continue
			}
			for _, uri := range rdep.CompiledGoFiles {
				fh, err := snapshot.ReadFile(ctx, uri)
				if err != nil {
					return nil, err
				}
				f, err := snapshot.ParseGo(ctx, fh, parsego.Header)
				if err != nil {
					return nil, err
				}
				for _, imp := range f.File.Imports {
					if rdep.DepsByImpPath[metadata.UnquoteImportPath(imp)] == narrowest.ID {
						refs = append(refs, reference{
							isDeclaration: false,
							location:      mustLocation(f, imp),
							pkgPath:       narrowest.PkgPath,
						})
					}
				}
			}
		}
	}

	// Find internal "references" to the package from
	// of each package declaration in the target package itself.
	//
	// The widest package (possibly a test variant) has the
	// greatest number of files and thus we choose it for the
	// "internal" references.
	widest := metas[len(metas)-1] // may include _test.go files
	for _, uri := range widest.CompiledGoFiles {
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		f, err := snapshot.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			return nil, err
		}
		// golang/go#66250: don't crash if the package file lacks a name.
		if f.File.Name.Pos().IsValid() {
			refs = append(refs, reference{
				isDeclaration: true, // (one of many)
				location:      mustLocation(f, f.File.Name),
				pkgPath:       widest.PkgPath,
			})
		}
	}

	return refs, nil
}

// ordinaryReferences computes references for all ordinary objects (not package declarations).
func ordinaryReferences(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, rng protocol.Range) ([]reference, error) {
	// Strategy: use the reference information computed by the
	// type checker to find the declaration. First type-check this
	// package to find the declaration, then type check the
	// declaring package (which may be different), plus variants,
	// to find local (in-package) references.
	// Global references are satisfied by the index.

	// Strictly speaking, a wider package could provide a different
	// declaration (e.g. because the _test.go files can change the
	// meaning of a field or method selection), but the narrower
	// package reports the more broadly referenced object.
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, uri)
	if err != nil {
		return nil, err
	}

	// Find the selected object (declaration or reference).
	// For struct{T}, we choose the field (Def) over the type (Use).
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(start, end) // can't fail

	candidates, err := objectsAt(pkg.TypesInfo(), cur)
	if err != nil {
		return nil, err
	}
	// Pick first object arbitrarily.
	// The case variables of a type switch have different
	// types but that difference is immaterial here.
	obj := candidates[0].obj

	// nil, error, error.Error, iota, or other built-in?
	if isBuiltin(obj) {
		return nil, fmt.Errorf("references to builtin %q are not supported", obj.Name())
	}

	// Find metadata of all packages containing the object's defining file.
	// This may include the query pkg, and possibly other variants.
	declPosn := safetoken.StartPosition(pkg.FileSet(), obj.Pos())
	declURI := protocol.URIFromPath(declPosn.Filename)
	variants, err := snapshot.MetadataForFile(ctx, declURI, false)
	if err != nil {
		return nil, err
	}
	if len(variants) == 0 {
		return nil, fmt.Errorf("no packages for file %q", declURI) // can't happen
	}
	// (variants must include ITVs for reverse dependency computation below.)

	// Is object exported?
	// If so, compute scope and targets of the global search.
	var (
		globalScope   = make(map[PackageID]*metadata.Package) // (excludes ITVs)
		globalTargets map[PackagePath]map[objectpath.Path]unit
		expansions    = make(map[PackageID]unit) // packages that caused search expansion
	)
	// TODO(adonovan): what about generic functions? Need to consider both
	// uninstantiated and instantiated. The latter have no objectpath. Use Origin?
	if path, err := objectpath.For(obj); err == nil && obj.Exported() {
		pkgPath := variants[0].PkgPath // (all variants have same package path)
		globalTargets = map[PackagePath]map[objectpath.Path]unit{
			pkgPath: {path: {}}, // primary target
		}

		// Compute set of (non-ITV) workspace packages.
		// We restrict references to this subset.
		workspace, err := snapshot.WorkspaceMetadata(ctx)
		if err != nil {
			return nil, err
		}
		workspaceMap := make(map[PackageID]*metadata.Package, len(workspace))
		workspaceIDs := make([]PackageID, 0, len(workspace))
		for _, mp := range workspace {
			workspaceMap[mp.ID] = mp
			workspaceIDs = append(workspaceIDs, mp.ID)
		}

		// addRdeps expands the global scope to include the
		// reverse dependencies of the specified package.
		addRdeps := func(id PackageID, transitive bool) error {
			rdeps, err := snapshot.ReverseDependencies(ctx, id, transitive)
			if err != nil {
				return err
			}
			for rdepID, rdep := range rdeps {
				// Skip non-workspace packages.
				//
				// This means we also skip any expansion of the
				// search that might be caused by a non-workspace
				// package, possibly causing us to miss references
				// to the expanded target set from workspace packages.
				//
				// TODO(adonovan): don't skip those expansions.
				// The challenge is how to so without type-checking
				// a lot of non-workspace packages not covered by
				// the initial workspace load.
				if _, ok := workspaceMap[rdepID]; !ok {
					continue
				}

				globalScope[rdepID] = rdep
			}
			return nil
		}

		// How far need we search?
		// For package-level objects, we need only search the direct importers.
		// For fields and methods, we must search transitively.
		transitive := obj.Pkg().Scope().Lookup(obj.Name()) != obj

		// The scope is the union of rdeps of each variant.
		// (Each set is disjoint so there's no benefit to
		// combining the metadata graph traversals.)
		for _, mp := range variants {
			if err := addRdeps(mp.ID, transitive); err != nil {
				return nil, err
			}
		}

		// Is object a method?
		//
		// If so, expand the search so that the targets include
		// all methods that correspond to it through interface
		// satisfaction, and the scope includes the rdeps of
		// the package that declares each corresponding type.
		//
		// 'expansions' records the packages that declared
		// such types.
		if recv := effectiveReceiver(obj); recv != nil {
			if err := expandMethodSearch(ctx, snapshot, workspaceIDs, obj.(*types.Func), recv, addRdeps, globalTargets, expansions); err != nil {
				return nil, err
			}
		}
	}

	// The search functions will call report(loc) for each hit.
	var (
		refsMu sync.Mutex
		refs   []reference
	)
	report := func(loc protocol.Location, isDecl bool) {
		ref := reference{
			isDeclaration: isDecl,
			location:      loc,
			pkgPath:       pkg.Metadata().PkgPath,
		}
		refsMu.Lock()
		refs = append(refs, ref)
		refsMu.Unlock()
	}

	// Loop over the variants of the declaring package,
	// and perform both the local (in-package) and global
	// (cross-package) searches, in parallel.
	//
	// TODO(adonovan): opt: support LSP reference streaming. See:
	// - https://github.com/microsoft/vscode-languageserver-node/pull/164
	// - https://github.com/microsoft/language-server-protocol/pull/182
	//
	// Careful: this goroutine must not return before group.Wait.
	var group errgroup.Group

	// Compute local references for each variant.
	// The target objects are identified by (URI, offset).
	for _, mp := range variants {
		// We want the ordinary importable package,
		// plus any test-augmented variants, since
		// declarations in _test.go files may change
		// the reference of a selection, or even a
		// field into a method or vice versa.
		//
		// But we don't need intermediate test variants,
		// as their local references will be covered
		// already by other variants.
		if mp.IsIntermediateTestVariant() {
			continue
		}
		mp := mp
		group.Go(func() error {
			// TODO(adonovan): opt: batch these TypeChecks.
			pkgs, err := snapshot.TypeCheck(ctx, mp.ID)
			if err != nil {
				return err
			}
			pkg := pkgs[0]

			// Find the declaration of the corresponding
			// object in this package based on (URI, offset).
			pgf, err := pkg.File(declURI)
			if err != nil {
				return err
			}
			pos, err := safetoken.Pos(pgf.Tok, declPosn.Offset)
			if err != nil {
				return err
			}
			cur, _ := pgf.Cursor().FindByPos(pos, pos) // can't fail

			objects, err := objectsAt(pkg.TypesInfo(), cur)
			if err != nil {
				return err // unreachable? (probably caught earlier)
			}

			// Report the locations of the declaration(s).
			// TODO(adonovan): what about for corresponding methods? Add tests.
			for _, o := range objects {
				report(mustLocation(pgf, o.cur.Node()), true)
			}

			// Convert objects list to targets set.
			targets := make(map[types.Object]bool)
			for _, o := range objects {
				targets[o.obj] = true
			}

			return localReferences(pkg, targets, true, report)
		})
	}

	// Also compute local references within packages that declare
	// corresponding methods (see above), which expand the global search.
	// The target objects are identified by (PkgPath, objectpath).
	for id := range expansions {
		group.Go(func() error {
			// TODO(adonovan): opt: batch these TypeChecks.
			pkgs, err := snapshot.TypeCheck(ctx, id)
			if err != nil {
				return err
			}
			pkg := pkgs[0]

			targets := make(map[types.Object]bool)
			for objpath := range globalTargets[pkg.Metadata().PkgPath] {
				obj, err := objectpath.Object(pkg.Types(), objpath)
				if err != nil {
					// No such object, because it was
					// declared only in the test variant.
					continue
				}
				targets[obj] = true
			}

			// Don't include corresponding types or methods
			// since expansions did that already, and we don't
			// want (e.g.) concrete -> interface -> concrete.
			const correspond = false
			return localReferences(pkg, targets, correspond, report)
		})
	}

	// Compute global references for selected reverse dependencies.
	group.Go(func() error {
		var globalIDs []PackageID
		for id := range globalScope {
			globalIDs = append(globalIDs, id)
		}
		indexes, err := snapshot.References(ctx, globalIDs...)
		if err != nil {
			return err
		}
		for _, index := range indexes {
			for _, loc := range index.Lookup(globalTargets) {
				report(loc, false)
			}
		}
		return nil
	})

	if err := group.Wait(); err != nil {
		return nil, err
	}
	return refs, nil
}

// expandMethodSearch expands the scope and targets of a global search
// for an exported method to include all methods in the workspace
// that correspond to it through interface satisfaction.
//
// Each package that declares a corresponding type is added to
// expansions so that we can also find local references to the type
// within the package, which of course requires type checking.
//
// The scope is expanded by a sequence of calls (not concurrent) to addRdeps.
//
// recv is the method's effective receiver type, for method-set computations.
func expandMethodSearch(ctx context.Context, snapshot *cache.Snapshot, workspaceIDs []PackageID, method *types.Func, recv types.Type, addRdeps func(id PackageID, transitive bool) error, targets map[PackagePath]map[objectpath.Path]unit, expansions map[PackageID]unit) error {
	// Compute the method-set fingerprint used as a key to the global search.
	key, hasMethods := methodsets.KeyOf(recv)
	if !hasMethods {
		// The query object was method T.m, but methodset(T)={}:
		// this indicates that ill-typed T has conflicting fields and methods.
		// Rather than bug-report (#67978), treat the empty method set at face value.
		return nil
	}
	// Search the methodset index of each package in the workspace.
	indexes, err := snapshot.MethodSets(ctx, workspaceIDs...)
	if err != nil {
		return err
	}
	var mu sync.Mutex // guards addRdeps, targets, expansions
	var group errgroup.Group
	for i, index := range indexes {
		group.Go(func() error {
			// Consult index for matching (super/sub) methods.
			const want = methodsets.Supertype | methodsets.Subtype
			results := index.Search(key, want, method)
			if len(results) == 0 {
				return nil
			}

			// We have discovered one or more corresponding types.
			id := workspaceIDs[i]

			mu.Lock()
			defer mu.Unlock()

			// Expand global search scope to include rdeps of this pkg.
			if err := addRdeps(id, true); err != nil {
				return err
			}

			// Mark this package so that we search within it for
			// local references to the additional types/methods.
			expansions[id] = unit{}

			// Add each corresponding method the to set of global search targets.
			for _, res := range results {
				methodPkg := PackagePath(res.PkgPath)
				opaths, ok := targets[methodPkg]
				if !ok {
					opaths = make(map[objectpath.Path]unit)
					targets[methodPkg] = opaths
				}
				opaths[res.ObjectPath] = unit{}
			}
			return nil
		})
	}
	return group.Wait()
}

// localReferences traverses syntax and reports each reference to one
// of the target objects, or (if correspond is set) an object that
// corresponds to one of them via interface satisfaction.
func localReferences(pkg *cache.Package, targets map[types.Object]bool, correspond bool, report func(loc protocol.Location, isDecl bool)) error {
	// If we're searching for references to a method optionally
	// broaden the search to include references to corresponding
	// methods of mutually assignable receiver types.
	// (We use a slice, but objectsAt never returns >1 methods.)
	var methodRecvs []types.Type
	var methodName string // name of an arbitrary target, iff a method
	if correspond {
		for obj := range targets {
			if t := effectiveReceiver(obj); t != nil {
				methodRecvs = append(methodRecvs, t)
				methodName = obj.Name()
			}
		}
	}

	var msets typeutil.MethodSetCache

	// matches reports whether obj either is or corresponds to a target.
	// (Correspondence is defined as usual for interface methods: super/subtype.)
	matches := func(obj types.Object) bool {
		if containsOrigin(targets, obj) {
			return true
		}
		if methodRecvs != nil && obj.Name() == methodName {
			if orecv := effectiveReceiver(obj); orecv != nil {
				for _, mrecv := range methodRecvs {
					if implements(&msets, orecv, mrecv) ||
						implements(&msets, mrecv, orecv) {
						return true
					}
				}
			}
		}
		return false
	}

	// Scan through syntax looking for uses of one of the target objects.
	for _, pgf := range pkg.CompiledGoFiles() {
		for curId := range pgf.Cursor().Preorder((*ast.Ident)(nil)) {
			id := curId.Node().(*ast.Ident)
			if obj, ok := pkg.TypesInfo().Uses[id]; ok && matches(obj) {
				report(mustLocation(pgf, id), false)
			}
		}
	}
	return nil
}

// effectiveReceiver returns the effective receiver type for method-set
// comparisons for obj, if it is a method, or nil otherwise.
func effectiveReceiver(obj types.Object) types.Type {
	if fn, ok := obj.(*types.Func); ok {
		if recv := fn.Signature().Recv(); recv != nil {
			return methodsets.EnsurePointer(recv.Type())
		}
	}
	return nil
}

type objectAt struct {
	obj types.Object     // symbol
	cur inspector.Cursor // associated syntax (Ident | ImportSpec)
}

// objectsAt returns the non-empty list of objects referenced (defined
// or used) at or near the position specified by cur. It returns an
// error if none were found.
//
// The implementation may look "nearby", for example at x when given
// a cursor to an expression "*x", i.e. the cursor was at the star.
//
// The result may contain more than one element because all case
// variables of a type switch appear to be declared at the same
// identifier.
//
// Each object is paired with a cursor for the syntax node that was
// treated as an identifier, which is not always an ast.Ident.
func objectsAt(info *types.Info, cur inspector.Cursor) ([]objectAt, error) {

	// Within an ImportSpec, return the PkgName
	// and its .Name (if explicit) or the spec if not.
	if cur.ParentEdgeKind() == edge.ImportSpec_Path {
		cur = cur.Parent() // ImportSpec
		spec := cur.Node().(*ast.ImportSpec)
		pkgname := info.PkgNameOf(spec)
		if pkgname == nil {
			return nil, fmt.Errorf("%w for import %s", errNoObjectFound, metadata.UnquoteImportPath(spec))
		}
		if spec.Name != nil { // explicit?
			cur = cur.ChildAt(edge.ImportSpec_Name, -1) // Ident
		}
		return []objectAt{{pkgname, cur}}, nil
	}

	// If the selection is the * of *T or *ptr,
	// nudge it to the T or ptr operand in the hope
	// that it is an Ident. This makes (e.g.) Hover and
	// Definition more flexible w.r.t selections:
	if is[*ast.StarExpr](cur.Node()) {
		cur, _ = cur.FirstChild() // can't fail
	}

	id, ok := cur.Node().(*ast.Ident)
	if !ok {
		return nil, ErrNoIdentFound
	}

	// If id is a reference to a special var v in
	//  switch v := expr.(type) { case T: use(v); ... }
	// then return all the implicit case vars.
	objects, _ := typeSwitchVars(info, cur)
	if len(objects) > 0 {
		return objects, nil
	}

	// All other identifiers.
	// For struct{T}, we prefer the defined field Var over the used TypeName.
	obj := info.ObjectOf(id)
	if obj == nil {
		return nil, fmt.Errorf("%w for %q", errNoObjectFound, id.Name)
	}
	return []objectAt{{obj, cur}}, nil
}

// typeSwitchVars returns information about type switch local variables.
//
// Given the cursor for an identifier that refers to a variable v
// declared by a type switch of this form:
//
//	switch v := expr.(type) {
//	case T: use(v)
//	...
//	}
//
// it returns:
//
//   - the (possibly empty) list of variables implicitly declared for
//     each case type; and
//
//   - the identifier's effective type, which is either the case type
//     (for an occurrence in a case), or the type of 'expr' for the
//     occurrence in "switch v".
//
// The identifier may be v in "switch v", or a use of it in one of the
// cases. typeSwitchVars returns zero for all other identifiers.
func typeSwitchVars(info *types.Info, curIdent inspector.Cursor) ([]objectAt, types.Type) {
	sw, curSwitch := cursorutil.FirstEnclosing[*ast.TypeSwitchStmt](curIdent)
	if sw == nil {
		return nil, nil
	}
	assign, ok := sw.Assign.(*ast.AssignStmt)
	if !(ok &&
		len(assign.Lhs) == 1 &&
		is[*ast.Ident](assign.Lhs[0]) &&
		len(assign.Rhs) == 1 &&
		is[*ast.TypeAssertExpr](assign.Rhs[0])) {
		return nil, nil
	}
	// Have: switch v := expr.(type)

	id := curIdent.Node().(*ast.Ident)

	match := false

	// Is selected ident "switch v" var?
	// Since it has no object, use the type of 'expr'.
	var t types.Type
	if id == assign.Lhs[0] {
		match = true
		t = info.TypeOf(assign.Rhs[0].(*ast.TypeAssertExpr).X) // may be nil
	}

	// Gather the switch's implicit variables.
	var objects []objectAt
	for curCase := range curSwitch.ChildAt(edge.TypeSwitchStmt_Body, -1).Children() {
		clause := curCase.Node().(*ast.CaseClause)
		v, ok := info.Implicits[clause]
		if ok {
			if v == info.Uses[id] {
				// Selected ident is one of the case vars.
				t = v.Type()
				match = true
			}
			objects = append(objects, objectAt{v, curIdent})
		}
	}

	if !match {
		// Type switch is unrelated to ident.
		return nil, nil
	}

	// Note: match does not imply t != nil,
	// as type information may be incomplete.

	return objects, t
}

// mustLocation reports the location interval a syntax node,
// which must belong to m.File.
//
// Safe for use only by references and implementations.
func mustLocation(pgf *parsego.File, n ast.Node) protocol.Location {
	loc, err := pgf.NodeLocation(n)
	if err != nil {
		panic(err) // can't happen in references or implementations
	}
	return loc
}


================================================
FILE: gopls/internal/golang/rename.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// TODO(adonovan):
//
// - method of generic concrete type -> arbitrary instances of same
//
// - make satisfy work across packages.
//
// - tests, tests, tests:
//   - play with renamings in the k8s tree.
//   - generics
//   - error cases (e.g. conflicts)
//   - renaming a symbol declared in the module cache
//     (currently proceeds with half of the renaming!)
//   - make sure all tests have both a local and a cross-package analogue.
//   - look at coverage
//   - special cases: embedded fields, interfaces, test variants,
//     function-local things with uppercase names;
//     packages with type errors (currently 'satisfy' rejects them),
//     package with missing imports;
//
// - measure performance in k8s.
//
// - The original gorename tool assumed well-typedness, but the gopls feature
//   does no such check (which actually makes it much more useful).
//   Audit to ensure it is safe on ill-typed code.
//
// - Generics support was no doubt buggy before but incrementalization
//   may have exacerbated it. If the problem were just about objects,
//   defs and uses it would be fairly simple, but type assignability
//   comes into play in the 'satisfy' check for method renamings.
//   De-instantiating Vector[int] to Vector[T] changes its type.
//   We need to come up with a theory for the satisfy check that
//   works with generics, and across packages. We currently have no
//   simple way to pass types between packages (think: objectpath for
//   types), though presumably exportdata could be pressed into service.
//
// - FileID-based de-duplication of edits to different URIs for the same file.

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/parser"
	"go/printer"
	"go/token"
	"go/types"
	"maps"
	"os"
	"path/filepath"
	"regexp"
	"slices"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/mod/modfile"
	goastutil "golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/pathutil"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/refactor/satisfy"
)

// A renamer holds state of a single call to renameObj, which renames
// an object (or several coupled objects) within a single type-checked
// syntax package.
type renamer struct {
	pkg                *cache.Package        // the syntax package in which the renaming is applied
	objsToUpdate       map[types.Object]bool // records progress of calls to check
	conflicts          []string
	from, to           string
	satisfyConstraints map[satisfy.Constraint]bool
	msets              typeutil.MethodSetCache
	changeMethods      bool
}

// A PrepareItem holds the result of a "prepare rename" operation:
// the source range and value of a selected identifier.
type PrepareItem struct {
	Range protocol.Range
	Text  string
}

// PrepareRename searches for a valid renaming at position pp.
//
// The returned usererr is intended to be displayed to the user to explain why
// the prepare fails. Probably we could eliminate the redundancy in returning
// two errors, but for now this is done defensively.
func PrepareRename(ctx context.Context, snapshot *cache.Snapshot, f file.Handle, rng protocol.Range) (_ *PrepareItem, usererr, err error) {
	ctx, done := event.Start(ctx, "golang.PrepareRename")
	defer done()

	// Is the cursor within the package name declaration?
	if pgf, inPackageName, err := parsePackageNameDecl(ctx, snapshot, f, rng); err != nil {
		return nil, err, err
	} else if inPackageName {
		item, err := prepareRenamePackageName(ctx, snapshot, pgf)
		return item, err, err
	}

	// Ordinary (non-package) renaming.
	//
	// Type-check the current package, locate the reference at the position,
	// validate the object, and report its name and range.
	//
	// TODO(adonovan): in all cases below, we return usererr=nil,
	// which means we return (nil, nil) at the protocol
	// layer. This seems like a bug, or at best an exploitation of
	// knowledge of VSCode-specific behavior. Can we avoid that?
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, f.URI())
	if err != nil {
		return nil, nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(start, end) // can't fail

	// Check if we're in a 'func' keyword. If so, we hijack the renaming to
	// change the function signature.
	if item, err := prepareRenameFuncSignature(pgf, start, end, cur); err != nil {
		return nil, nil, err
	} else if item != nil {
		return item, nil, nil
	}

	targets, err := objectsAt(pkg.TypesInfo(), cur)
	if err != nil {
		// Check if we are renaming an ident inside its doc comment. The call to
		// objectsAt will have returned an error in this case.
		// TODO(adonovan): move this logic into objectsAt.
		var ok bool
		cur, ok = docCommentPosToIdent(pgf, start, end, cur)
		if !ok {
			return nil, nil, err
		}
		id := cur.Node().(*ast.Ident)
		obj := pkg.TypesInfo().Defs[id]
		if obj == nil {
			return nil, nil, fmt.Errorf("error fetching Object for ident %q", id.Name)
		}
		// Change rename target to the ident.
		targets = []objectAt{{obj, cur}}
	}

	// Pick a representative object arbitrarily.
	// (All share the same name, pos, and kind.)
	obj, node := targets[0].obj, targets[0].cur.Node()
	if err := checkRenamable(obj, node); err != nil {
		return nil, nil, err
	}
	nodeRng, err := pgf.NodeRange(node)
	if err != nil {
		return nil, nil, err
	}
	if _, isImport := node.(*ast.ImportSpec); isImport {
		// We're not really renaming the import path.
		nodeRng.End = nodeRng.Start
	}
	return &PrepareItem{
		Range: nodeRng,
		Text:  obj.Name(),
	}, nil, nil
}

func prepareRenamePackageName(ctx context.Context, snapshot *cache.Snapshot, pgf *parsego.File) (*PrepareItem, error) {
	// Does the client support file renaming?
	if !slices.Contains(snapshot.Options().SupportedResourceOperations, protocol.Rename) {
		return nil, errors.New("can't rename package: LSP client does not support file renaming")
	}

	// Check validity of the metadata for the file's containing package.
	meta, err := snapshot.NarrowestMetadataForFile(ctx, pgf.URI)
	if err != nil {
		return nil, err
	}
	if meta.Name == "main" {
		return nil, fmt.Errorf("can't rename package \"main\"")
	}
	// TODO(mkalil): support renaming x_test packages.
	if strings.HasSuffix(string(meta.Name), "_test") {
		return nil, fmt.Errorf("can't rename x_test packages")
	}
	if meta.Module == nil {
		return nil, fmt.Errorf("can't rename package: missing module information for package %q", meta.PkgPath)
	}
	// TODO(mkalil): why is renaming the root package of a module unsupported?
	if meta.Module.Path == string(meta.PkgPath) {
		return nil, fmt.Errorf("can't rename package: package path %q is the same as module path %q", meta.PkgPath, meta.Module.Path)
	}

	// Return the location of the package declaration.
	rng, err := pgf.NodeRange(pgf.File.Name)
	if err != nil {
		return nil, err
	}

	return &PrepareItem{
		Range: rng,
		Text:  string(meta.PkgPath),
	}, nil
}

// prepareRenameFuncSignature prepares a change signature refactoring initiated
// through invoking a rename request at the 'func' keyword of a function
// declaration.
//
// The resulting text is the signature of the function, which may be edited to
// the new signature.
func prepareRenameFuncSignature(pgf *parsego.File, start, end token.Pos, cursor inspector.Cursor) (*PrepareItem, error) {
	fdecl := funcKeywordDecl(start, end, cursor)
	if fdecl == nil {
		return nil, nil
	}
	ftyp := nameBlankParams(fdecl.Type)
	var buf bytes.Buffer
	if err := printer.Fprint(&buf, token.NewFileSet(), ftyp); err != nil { // use a new fileset so that the signature is formatted on a single line
		return nil, err
	}
	rng, err := pgf.PosRange(ftyp.Func, ftyp.Func+token.Pos(len("func")))
	if err != nil {
		return nil, err
	}
	text := buf.String()
	return &PrepareItem{
		Range: rng,
		Text:  text,
	}, nil
}

// nameBlankParams returns a copy of ftype with blank or unnamed params
// assigned a unique name.
func nameBlankParams(ftype *ast.FuncType) *ast.FuncType {
	ftype = astutil.CloneNode(ftype)

	// First, collect existing names.
	scope := make(map[string]bool)
	for name := range astutil.FlatFields(ftype.Params) {
		if name != nil {
			scope[name.Name] = true
		}
	}
	blanks := 0
	for name, field := range astutil.FlatFields(ftype.Params) {
		if name == nil {
			name = ast.NewIdent("_")
			field.Names = append(field.Names, name) // ok to append
		}
		if name.Name == "" || name.Name == "_" {
			for {
				newName := fmt.Sprintf("_%d", blanks)
				blanks++
				if !scope[newName] {
					name.Name = newName
					break
				}
			}
		}
	}
	return ftype
}

// renameFuncSignature computes and applies the effective change signature
// operation resulting from a 'renamed' (=rewritten) signature.
func renameFuncSignature(ctx context.Context, pkg *cache.Package, pgf *parsego.File, start, end token.Pos, snapshot *cache.Snapshot, cursor inspector.Cursor, f file.Handle, rng protocol.Range, newName string) (map[protocol.DocumentURI][]protocol.TextEdit, error) {
	fdecl := funcKeywordDecl(start, end, cursor)
	if fdecl == nil {
		return nil, nil
	}
	ftyp := nameBlankParams(fdecl.Type)

	// Parse the user's requested new signature.
	parsed, err := parser.ParseExpr(newName)
	if err != nil {
		return nil, err
	}
	newType, _ := parsed.(*ast.FuncType)
	if newType == nil {
		return nil, fmt.Errorf("parsed signature is %T, not a function type", parsed)
	}

	// Check results, before we get into handling permutations of parameters.
	if got, want := newType.Results.NumFields(), ftyp.Results.NumFields(); got != want {
		return nil, fmt.Errorf("changing results not yet supported (got %d results, want %d)", got, want)
	}
	var resultTypes []string
	for _, field := range astutil.FlatFields(ftyp.Results) {
		resultTypes = append(resultTypes, FormatNode(token.NewFileSet(), field.Type))
	}
	resultIndex := 0
	for _, field := range astutil.FlatFields(newType.Results) {
		if FormatNode(token.NewFileSet(), field.Type) != resultTypes[resultIndex] {
			return nil, fmt.Errorf("changing results not yet supported")
		}
		resultIndex++
	}

	type paramInfo struct {
		idx int
		typ string
	}
	oldParams := make(map[string]paramInfo)
	for name, field := range astutil.FlatFields(ftyp.Params) {
		oldParams[name.Name] = paramInfo{
			idx: len(oldParams),
			typ: types.ExprString(field.Type),
		}
	}

	var newParams []int
	for name, field := range astutil.FlatFields(newType.Params) {
		if name == nil {
			return nil, fmt.Errorf("need named fields")
		}
		info, ok := oldParams[name.Name]
		if !ok {
			return nil, fmt.Errorf("couldn't find name %s: adding parameters not yet supported", name)
		}
		if newType := types.ExprString(field.Type); newType != info.typ {
			return nil, fmt.Errorf("changing types (%s to %s) not yet supported", info.typ, newType)
		}
		newParams = append(newParams, info.idx)
	}

	funcRng, err := pgf.PosRange(ftyp.Func, ftyp.Func)
	if err != nil {
		return nil, err
	}
	changes, err := ChangeSignature(ctx, snapshot, pkg, pgf, funcRng, newParams)
	if err != nil {
		return nil, err
	}
	transposed := make(map[protocol.DocumentURI][]protocol.TextEdit)
	for _, change := range changes {
		transposed[change.TextDocumentEdit.TextDocument.URI] = protocol.AsTextEdits(change.TextDocumentEdit.Edits)
	}
	return transposed, nil
}

// funcKeywordDecl returns the FuncDecl for which pos is in the 'func' keyword,
// if any.
func funcKeywordDecl(start, end token.Pos, cursor inspector.Cursor) *ast.FuncDecl {
	fdecl, _ := cursorutil.FirstEnclosing[*ast.FuncDecl](cursor)
	if fdecl == nil {
		return nil
	}
	ftyp := fdecl.Type
	if start < ftyp.Func || end > ftyp.Func+token.Pos(len("func")) { // tolerate renaming immediately after 'func'
		return nil
	}
	return fdecl
}

// checkRenamable returns an error if the object cannot be renamed.
// node is the name-like syntax node from which the renaming originated.
func checkRenamable(obj types.Object, node ast.Node) error {
	switch obj := obj.(type) {
	case *types.Var:
		// Allow renaming an embedded field only at its declaration.
		if obj.Embedded() && node.Pos() != obj.Pos() {
			return errors.New("an embedded field must be renamed at its declaration (since it renames the type too)")

		}
	case *types.Builtin, *types.Nil:
		return fmt.Errorf("%s is built in and cannot be renamed", obj.Name())
	}
	if obj.Pkg() == nil || obj.Pkg().Path() == "unsafe" {
		// e.g. error.Error, unsafe.Pointer
		return fmt.Errorf("%s is built in and cannot be renamed", obj.Name())
	}
	if obj.Name() == "_" {
		return errors.New("can't rename \"_\"")
	}
	return nil
}

// editsToDocChanges converts a map of uris to arrays of text edits to a list of document changes.
func editsToDocChanges(ctx context.Context, snapshot *cache.Snapshot, edits map[protocol.DocumentURI][]protocol.TextEdit) ([]protocol.DocumentChange, error) {
	var changes []protocol.DocumentChange
	for uri, e := range edits {
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		changes = append(changes, protocol.DocumentChangeEdit(fh, e))
	}
	return changes, nil
}

// Rename returns a map of TextEdits for each file modified when renaming a
// given identifier within a package.
func Rename(ctx context.Context, snapshot *cache.Snapshot, f file.Handle, rng protocol.Range, newName string) ([]protocol.DocumentChange, error) {
	ctx, done := event.Start(ctx, "golang.Rename")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, f.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}

	cur, ok := pgf.Cursor().FindByPos(start, end)
	if !ok {
		return nil, fmt.Errorf("can't find cursor for selection")
	}

	if edits, err := renameFuncSignature(ctx, pkg, pgf, start, end, snapshot, cur, f, rng, newName); err != nil {
		return nil, err
	} else if edits != nil {
		return editsToDocChanges(ctx, snapshot, edits)
	}

	// Cursor within package name declaration?
	_, inPackageName, err := parsePackageNameDecl(ctx, snapshot, f, rng)
	if err != nil {
		return nil, err
	}

	var (
		editMap   map[protocol.DocumentURI][]diff.Edit
		newPkgDir string // declared here so it can be used later to move the package's contents to the new directory
	)
	if inPackageName {
		countRenamePackage.Inc()
		var (
			newPkgName PackageName
			newPkgPath PackagePath
			err        error
		)
		moveSubpackages := snapshot.Options().RenameMovesSubpackages
		if newPkgDir, newPkgName, newPkgPath, err = checkPackageRename(pkg, f, newName, moveSubpackages); err != nil {
			return nil, err
		}
		editMap, err = renamePackage(ctx, snapshot, f, newPkgName, newPkgPath, newPkgDir, moveSubpackages)
		if err != nil {
			return nil, err
		}
	} else {
		if !isValidIdentifier(newName) {
			return nil, fmt.Errorf("invalid identifier to rename: %q", newName)
		}
		editMap, err = renameOrdinary(ctx, snapshot, f.URI(), rng, newName)
		if err != nil {
			return nil, err
		}
	}

	// Convert edits to protocol form.
	result := make(map[protocol.DocumentURI][]protocol.TextEdit)
	for uri, edits := range editMap {
		// Sort and de-duplicate edits.
		//
		// Overlapping edits may arise in local renamings (due
		// to type switch implicits) and globals ones (due to
		// processing multiple package variants).
		//
		// We assume renaming produces diffs that are all
		// replacements (no adjacent insertions that might
		// become reordered) and that are either identical or
		// non-overlapping.
		diff.SortEdits(edits)
		edits = slices.Compact(edits)

		// TODO(adonovan): the logic above handles repeat edits to the
		// same file URI (e.g. as a member of package p and p_test) but
		// is not sufficient to handle file-system level aliasing arising
		// from symbolic or hard links. For that, we should use a
		// robustio-FileID-keyed map.
		// See https://go.dev/cl/457615 for example.
		// This really occurs in practice, e.g. kubernetes has
		// vendor/k8s.io/kubectl -> ../../staging/src/k8s.io/kubectl.
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		data, err := fh.Content()
		if err != nil {
			return nil, err
		}
		m := protocol.NewMapper(uri, data)
		textedits, err := protocol.EditsFromDiffEdits(m, edits)
		if err != nil {
			return nil, err
		}
		result[uri] = textedits
	}

	changes, err := editsToDocChanges(ctx, snapshot, result)
	if err != nil {
		return nil, err
	}
	if inPackageName {
		oldDir := f.URI().DirPath()
		if snapshot.Options().RenameMovesSubpackages {
			// Update the last component of the file's enclosing directory.
			changes = append(changes, protocol.DocumentChangeRename(
				protocol.URIFromPath(oldDir),
				protocol.URIFromPath(newPkgDir)))
		} else {
			// Not moving subpackages, so we need to move the files individually
			// Move each file from oldDir to newPkgDir
			files, err := os.ReadDir(oldDir)
			if err != nil {
				return nil, err
			}
			hasNestedDir := false
			for _, f := range files {
				if !f.IsDir() {
					changes = append(changes,
						protocol.DocumentChangeRename(
							protocol.URIFromPath(filepath.Join(oldDir, f.Name())),
							protocol.URIFromPath(filepath.Join(newPkgDir, f.Name()))),
					)
				} else {
					hasNestedDir = true
				}
			}
			// Delete oldPkgDir if it is now empty and newPkgDir is not a subdirectory of oldPkgDir.
			// protocol.DeleteFile, when used with a directory, will only delete the directory
			// if it is empty as long as the "recursive" option is set to its default value, false.
			// TODO(mkalil): The above should be true according to the LSP spec but in VSCode
			// we could get "Renamed failed to apply edits" errors when we include the edit
			// to delete a directory that can't be deleted. For now, check if the oldDir has
			// any nested directories before trying to delete it.
			// TODO(mkalil): We could be deleting more directories. For example, if
			// we have a package at a/b/c/d and we move it to a/z, it only deletes
			// directory d and would leave directories b and c even if they are now
			// empty.
			oldPkgDir := f.URI().DirPath()
			if !pathutil.InDir(oldPkgDir, newPkgDir) && !hasNestedDir {
				changes = append(changes,
					protocol.DocumentChangeDelete(protocol.URIFromPath(oldPkgDir)))
			}
		}
	}
	return changes, nil
}

// renameOrdinary renames an ordinary (non-package) name throughout the workspace.
func renameOrdinary(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, rng protocol.Range, newName string) (map[protocol.DocumentURI][]diff.Edit, error) {
	// Type-check the referring package and locate the object(s).
	//
	// Unlike NarrowestPackageForFile, this operation prefers the
	// widest variant as, for non-exported identifiers, it is the
	// only package we need. (In case you're wondering why
	// 'references' doesn't also want the widest variant: it
	// computes the union across all variants.)
	mps, err := snapshot.MetadataForFile(ctx, uri, true)
	if err != nil {
		return nil, err
	}
	if len(mps) == 0 {
		return nil, fmt.Errorf("no package metadata for file %s", uri)
	}
	widest := mps[len(mps)-1] // widest variant may include _test.go files
	pkgs, err := snapshot.TypeCheck(ctx, widest.ID)
	if err != nil {
		return nil, err
	}
	pkg := pkgs[0]
	pgf, err := pkg.File(uri)
	if err != nil {
		return nil, err // "can't happen"
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(start, end) // cannot fail

	targets, err := objectsAt(pkg.TypesInfo(), cur)
	if err != nil {
		// Check if we are renaming an ident inside its doc comment. The call to
		// objectsAt will have returned an error in this case.
		// TODO(adonovan): move this logic into objectsAt.
		var ok bool
		cur, ok = docCommentPosToIdent(pgf, start, end, cur)
		if !ok {
			return nil, err
		}
		id := cur.Node().(*ast.Ident)
		obj := pkg.TypesInfo().Defs[id]
		if obj == nil {
			return nil, fmt.Errorf("error fetching types.Object for ident %q", id.Name)
		}
		// Change rename target to the ident.
		targets = []objectAt{{obj, cur}}
	}

	// Pick a representative object arbitrarily.
	// (All share the same name, pos, and kind.)
	obj, node := targets[0].obj, targets[0].cur.Node()
	if obj.Name() == newName {
		return nil, fmt.Errorf("old and new names are the same: %s", newName)
	}
	if err := checkRenamable(obj, node); err != nil {
		return nil, err
	}

	// This covers the case where we are renaming an embedded field at its
	// declaration (see golang/go#45199). Perform the rename on the field's type declaration.
	if is[*types.Var](obj) && obj.(*types.Var).Embedded() {
		if id, ok := node.(*ast.Ident); ok {
			// TypesInfo.Uses contains the embedded field's *types.TypeName.
			if typeName := pkg.TypesInfo().Uses[id]; typeName != nil {
				loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, typeName)
				if err != nil {
					return nil, err
				}
				return renameOrdinary(ctx, snapshot, loc.URI, loc.Range, newName)
			}
		}
	}

	// Find objectpath, if object is exported ("" otherwise).
	var declObjPath objectpath.Path
	if obj.Exported() {
		// objectpath.For requires the origin of a generic function or type, not an
		// instantiation (a bug?).
		//
		// Note that unlike Funcs, TypeNames are always canonical (they are "left"
		// of the type parameters, unlike methods).
		switch obj0 := obj.(type) { // avoid "obj :=" since cases reassign the var
		case *types.TypeName:
			if _, ok := types.Unalias(obj.Type()).(*types.TypeParam); ok {
				// As with capitalized function parameters below, type parameters are
				// local.
				goto skipObjectPath
			}
		case *types.Func:
			obj = obj0.Origin()
		case *types.Var:
			// TODO(adonovan): do vars need the origin treatment too? (issue #58462)

			// Function parameter and result vars that are (unusually)
			// capitalized are technically exported, even though they
			// cannot be referenced, because they may affect downstream
			// error messages. But we can safely treat them as local.
			//
			// This is not merely an optimization: the renameExported
			// operation gets confused by such vars. It finds them from
			// objectpath, the classifies them as local vars, but as
			// they came from export data they lack syntax and the
			// correct scope tree (issue #61294).
			if !obj0.IsField() && !typesinternal.IsPackageLevel(obj) {
				goto skipObjectPath
			}
		}
		if path, err := objectpath.For(obj); err == nil {
			declObjPath = path
		}
	skipObjectPath:
	}

	// Nonexported? Search locally.
	if declObjPath == "" {
		var objects []types.Object
		for _, o := range targets {
			objects = append(objects, o.obj)
		}

		editMap, _, err := renameObjects(newName, pkg, objects...)
		if err != nil {
			return nil, err
		}

		// If the selected identifier is a receiver declaration,
		// also rename receivers of other methods of the same type
		// that don't already have the desired name.
		// Quietly discard edits from any that can't be renamed.
		//
		// We interpret renaming the receiver declaration as
		// intent for the broader renaming; renaming a use of
		// the receiver effects only the local renaming.
		if id, ok := cur.Node().(*ast.Ident); ok && id.Pos() == obj.Pos() {
			// enclosing func
			if decl, _ := cursorutil.FirstEnclosing[*ast.FuncDecl](cur); decl != nil {
				if decl.Recv != nil &&
					len(decl.Recv.List) > 0 &&
					len(decl.Recv.List[0].Names) > 0 {
					recv := pkg.TypesInfo().Defs[decl.Recv.List[0].Names[0]]
					if recv == obj {
						// TODO(adonovan): simplify the above 7 lines to
						// to "if obj.(*Var).Kind==Recv" in go1.25.
						renameReceivers(pkg, recv.(*types.Var), newName, editMap)
					}
				}
			}
		}
		return editMap, nil
	}

	// Exported: search globally.
	//
	// For exported package-level var/const/func/type objects, the
	// search scope is just the direct importers.
	//
	// For exported fields and methods, the scope is the
	// transitive rdeps. (The exportedness of the field's struct
	// or method's receiver is irrelevant.)
	transitive := false
	switch obj := obj.(type) {
	case *types.TypeName:
		// Renaming an exported package-level type
		// requires us to inspect all transitive rdeps
		// in the event that the type is embedded.
		//
		// TODO(adonovan): opt: this is conservative
		// but inefficient. Instead, expand the scope
		// of the search only if we actually encounter
		// an embedding of the type, and only then to
		// the rdeps of the embedding package.
		if obj.Parent() == obj.Pkg().Scope() {
			transitive = true
		}

	case *types.Var:
		if obj.IsField() {
			transitive = true // field
		}

		// TODO(adonovan): opt: process only packages that
		// contain a reference (xrefs) to the target field.

	case *types.Func:
		if obj.Signature().Recv() != nil {
			transitive = true // method
		}

		// It's tempting to optimize by skipping
		// packages that don't contain a reference to
		// the method in the xrefs index, but we still
		// need to apply the satisfy check to those
		// packages to find assignment statements that
		// might expands the scope of the renaming.
	}

	// Type-check all the packages to inspect.
	declURI := protocol.URIFromPath(pkg.FileSet().File(obj.Pos()).Name())
	pkgs, err = typeCheckReverseDependencies(ctx, snapshot, declURI, transitive)
	if err != nil {
		return nil, err
	}

	// Apply the renaming to the (initial) object.
	declPkgPath := PackagePath(obj.Pkg().Path())
	return renameExported(pkgs, declPkgPath, declObjPath, newName)
}

// renameReceivers renames all receivers of methods of the same named
// type as recv. The edits of each successful renaming are added to
// editMap; the failed ones are quietly discarded.
func renameReceivers(pkg *cache.Package, recv *types.Var, newName string, editMap map[protocol.DocumentURI][]diff.Edit) {
	_, named := typesinternal.ReceiverNamed(recv)
	if named == nil {
		return
	}

	// Find receivers of other methods of the same named type.
	for m := range named.Origin().Methods() {
		recv2 := m.Signature().Recv()
		if recv2 == recv {
			continue // don't re-rename original receiver
		}
		if recv2.Name() == newName {
			continue // no renaming needed
		}
		editMap2, _, err := renameObjects(newName, pkg, recv2)
		if err != nil {
			continue // ignore secondary failures
		}

		// Since all methods (and their comments)
		// are disjoint, and don't affect imports,
		// we can safely assume that all edits are
		// nonconflicting and disjoint.
		for uri, edits := range editMap2 {
			editMap[uri] = append(editMap[uri], edits...)
		}
	}
}

// typeCheckReverseDependencies returns the type-checked packages for
// the reverse dependencies of all packages variants containing
// file declURI. The packages are in some topological order.
//
// It includes all variants (even intermediate test variants) for the
// purposes of computing reverse dependencies, but discards ITVs for
// the actual renaming work.
//
// (This neglects obscure edge cases where a _test.go file changes the
// selectors used only in an ITV, but life is short. Also sin must be
// punished.)
func typeCheckReverseDependencies(ctx context.Context, snapshot *cache.Snapshot, declURI protocol.DocumentURI, transitive bool) ([]*cache.Package, error) {
	variants, err := snapshot.MetadataForFile(ctx, declURI, false)
	if err != nil {
		return nil, err
	}
	// variants must include ITVs for the reverse dependency
	// computation, but they are filtered out before we typecheck.
	allRdeps := make(map[PackageID]*metadata.Package)
	for _, variant := range variants {
		rdeps, err := snapshot.ReverseDependencies(ctx, variant.ID, transitive)
		if err != nil {
			return nil, err
		}
		allRdeps[variant.ID] = variant // include self
		maps.Copy(allRdeps, rdeps)
	}
	var ids []PackageID
	for id, meta := range allRdeps {
		if meta.IsIntermediateTestVariant() {
			continue
		}
		ids = append(ids, id)
	}

	// Sort the packages into some topological order of the
	// (unfiltered) metadata graph.
	metadata.SortPostOrder(snapshot, ids)

	// Dependencies must be visited first since they can expand
	// the search set. Ideally we would process the (filtered) set
	// of packages in the parallel postorder of the snapshot's
	// (unfiltered) metadata graph, but this is quite tricky
	// without a good graph abstraction.
	//
	// For now, we visit packages sequentially in order of
	// ascending height, like an inverted breadth-first search.
	//
	// Type checking is by far the dominant cost, so
	// overlapping it with renaming may not be worthwhile.
	return snapshot.TypeCheck(ctx, ids...)
}

// renameExported renames the object denoted by (pkgPath, objPath)
// within the specified packages, along with any other objects that
// must be renamed as a consequence. The slice of packages must be
// topologically ordered.
func renameExported(pkgs []*cache.Package, declPkgPath PackagePath, declObjPath objectpath.Path, newName string) (map[protocol.DocumentURI][]diff.Edit, error) {

	// A target is a name for an object that is stable across types.Packages.
	type target struct {
		pkg PackagePath
		obj objectpath.Path
	}

	// Populate the initial set of target objects.
	// This set may grow as we discover the consequences of each renaming.
	//
	// TODO(adonovan): strictly, each cone of reverse dependencies
	// of a single variant should have its own target map that
	// monotonically expands as we go up the import graph, because
	// declarations in test files can alter the set of
	// package-level names and change the meaning of field and
	// method selectors. So if we parallelize the graph
	// visitation (see above), we should also compute the targets
	// as a union of dependencies.
	//
	// Or we could decide that the logic below is fast enough not
	// to need parallelism. In small measurements so far the
	// type-checking step is about 95% and the renaming only 5%.
	targets := map[target]bool{{declPkgPath, declObjPath}: true}

	// Apply the renaming operation to each package.
	allEdits := make(map[protocol.DocumentURI][]diff.Edit)
	for _, pkg := range pkgs {

		// Resolved target objects within package pkg.
		var objects []types.Object
		for t := range targets {
			p := pkg.DependencyTypes(t.pkg)
			if p == nil {
				continue // indirect dependency of no consequence
			}
			obj, err := objectpath.Object(p, t.obj)
			if err != nil {
				// Possibly a method or an unexported type
				// that is not reachable through export data?
				// See https://github.com/golang/go/issues/60789.
				//
				// TODO(adonovan): it seems unsatisfactory that Object
				// should return an error for a "valid" path. Perhaps
				// we should define such paths as invalid and make
				// objectpath.For compute reachability?
				// Would that be a compatible change?
				continue
			}
			objects = append(objects, obj)
		}
		if len(objects) == 0 {
			continue // no targets of consequence to this package
		}

		// Apply the renaming.
		editMap, moreObjects, err := renameObjects(newName, pkg, objects...)
		if err != nil {
			return nil, err
		}

		// It is safe to concatenate the edits as they are non-overlapping
		// (or identical, in which case they will be de-duped by Rename).
		for uri, edits := range editMap {
			allEdits[uri] = append(allEdits[uri], edits...)
		}

		// Expand the search set?
		for obj := range moreObjects {
			objpath, err := objectpath.For(obj)
			if err != nil {
				continue // not exported
			}
			target := target{PackagePath(obj.Pkg().Path()), objpath}
			targets[target] = true

			// TODO(adonovan): methods requires dynamic
			// programming of the product targets x
			// packages as any package might add a new
			// target (from a forward dep) as a
			// consequence, and any target might imply a
			// new set of rdeps. See golang/go#58461.
		}
	}

	return allEdits, nil
}

// renamePackage renames package declarations, imports, and go.mod files.
//
// f is the file originating the rename, and therefore f.URI().Dir() is the
// current package directory. newName, newPath, and newDir describe the renaming.
func renamePackage(ctx context.Context, s *cache.Snapshot, f file.Handle, newName PackageName, newPath PackagePath, newDir string, moveSubpackages bool) (map[protocol.DocumentURI][]diff.Edit, error) {
	// Rename the package decl and all imports.
	renamingEdits := make(map[protocol.DocumentURI][]diff.Edit)
	err := updatePackageDeclsAndImports(ctx, s, f, newName, newPath, renamingEdits, moveSubpackages)
	if err != nil {
		return nil, err
	}

	err = updateModFiles(ctx, s, f.URI().DirPath(), newDir, renamingEdits, moveSubpackages)
	if err != nil {
		return nil, err
	}

	return renamingEdits, nil
}

// Update any affected replace directives in go.mod files.
// TODO(adonovan): should this operate on all go.mod files,
// irrespective of whether they are included in the workspace?
func updateModFiles(ctx context.Context, s *cache.Snapshot, oldDir string, newPkgDir string, renamingEdits map[protocol.DocumentURI][]diff.Edit, moveSubpackages bool) error {
	modFiles := s.View().ModFiles()
	for _, m := range modFiles {
		fh, err := s.ReadFile(ctx, m)
		if err != nil {
			return err
		}
		pm, err := s.ParseMod(ctx, fh)
		if err != nil {
			return err
		}

		modFileDir := pm.URI.DirPath()
		affectedReplaces := []*modfile.Replace{}

		// Check if any replace directives need to be fixed
		for _, r := range pm.File.Replace {
			if !strings.HasPrefix(r.New.Path, "/") && !strings.HasPrefix(r.New.Path, "./") && !strings.HasPrefix(r.New.Path, "../") {
				continue
			}
			replacedDir := r.New.Path
			if strings.HasPrefix(r.New.Path, "./") || strings.HasPrefix(r.New.Path, "../") {
				replacedDir = filepath.Join(modFileDir, r.New.Path)
			}

			// TODO: Is there a risk of converting a '\' delimited replacement to a '/' delimited replacement?

			if moveSubpackages && !strings.HasPrefix(filepath.ToSlash(replacedDir)+"/", filepath.ToSlash(oldDir)+"/") ||
				!moveSubpackages && !(filepath.ToSlash(replacedDir) == filepath.ToSlash(oldDir)) {
				continue //not affected by the package renanming
			}

			affectedReplaces = append(affectedReplaces, r)
		}

		if len(affectedReplaces) == 0 {
			continue
		}
		copied, err := modfile.Parse("", pm.Mapper.Content, nil)
		if err != nil {
			return err
		}

		for _, r := range affectedReplaces {
			replacedDir := r.New.Path
			if strings.HasPrefix(r.New.Path, "./") || strings.HasPrefix(r.New.Path, "../") {
				replacedDir = filepath.Join(modFileDir, r.New.Path)
			}

			suffix := strings.TrimPrefix(replacedDir, oldDir)

			newReplacedPath, err := filepath.Rel(modFileDir, newPkgDir+suffix)
			if err != nil {
				return err
			}

			newReplacedPath = filepath.ToSlash(newReplacedPath)

			if !strings.HasPrefix(newReplacedPath, "/") && !strings.HasPrefix(newReplacedPath, "../") {
				newReplacedPath = "./" + newReplacedPath
			}

			if err := copied.AddReplace(r.Old.Path, "", newReplacedPath, ""); err != nil {
				return err
			}
		}

		copied.Cleanup()
		newContent, err := copied.Format()
		if err != nil {
			return err
		}

		// Calculate the edits to be made due to the change.
		edits := diff.Bytes(pm.Mapper.Content, newContent)
		renamingEdits[pm.URI] = append(renamingEdits[pm.URI], edits...)
	}
	return nil
}

// updatePackageDeclsAndImports computes all workspace edits required to rename the package
// described by the given metadata, to newName, by renaming its package
// directory.
//
// It updates package clauses and import paths for the renamed package as well
// as any other packages affected by the directory renaming among all packages
// known to the snapshot.
func updatePackageDeclsAndImports(ctx context.Context, s *cache.Snapshot, f file.Handle, newName PackageName, newPkgPath PackagePath, renamingEdits map[protocol.DocumentURI][]diff.Edit, moveSubpackages bool) error {
	if strings.HasSuffix(string(newName), "_test") {
		return fmt.Errorf("cannot rename to _test package")
	}

	// We need metadata for the relevant package and module paths.
	// These should be the same for all packages containing the file.
	meta, err := s.NarrowestMetadataForFile(ctx, f.URI())
	if err != nil {
		return err
	}

	oldPkgPath := meta.PkgPath
	if meta.Module == nil {
		return fmt.Errorf("cannot rename package: missing module information for package %q", meta.PkgPath)
	}
	modulePath := PackagePath(meta.Module.Path)
	if modulePath == oldPkgPath {
		return fmt.Errorf("cannot rename package: module path %q is the same as the package path, so renaming the package directory would have no effect", modulePath)
	}

	// We must inspect all packages, not just direct importers,
	// because we might also rename subpackages, which may be unrelated.
	// (If the renamed package imports a subpackage it may require
	// edits to both its package and import decls.)
	allMetadata, err := s.AllMetadata(ctx)
	if err != nil {
		return err
	}
	// Rename package and import declarations in all relevant packages.
	for _, mp := range allMetadata {
		// Special case: x_test packages for the renamed package will not have the
		// package path as a dir prefix, but still need their package clauses
		// renamed.
		if mp.PkgPath == oldPkgPath+"_test" {
			if err := renamePackageClause(ctx, mp, s, newName+"_test", renamingEdits); err != nil {
				return err
			}
			continue
		}

		// Subtle: check this condition before checking for valid module info
		// below, because we should not fail this operation if unrelated packages
		// lack module info.
		if moveSubpackages && !pathutil.InDir(filepath.FromSlash(string(oldPkgPath)), filepath.FromSlash(string(mp.PkgPath))) ||
			!moveSubpackages && mp.PkgPath != oldPkgPath {
			continue // not affected by the package renaming
		}

		if mp.Module == nil {
			// This check will always fail under Bazel.
			return fmt.Errorf("cannot rename package: missing module information for package %q", mp.PkgPath)
		}

		if modulePath != PackagePath(mp.Module.Path) {
			continue // don't edit imports if nested package and renaming package have different module paths
		}

		// Renaming a package consists of changing its import path and package name.
		suffix := strings.TrimPrefix(string(mp.PkgPath), string(oldPkgPath))
		newImportPath := string(newPkgPath) + suffix

		pkgName := mp.Name
		if mp.PkgPath == oldPkgPath {
			pkgName = newName

			if err := renamePackageClause(ctx, mp, s, newName, renamingEdits); err != nil {
				return err
			}
		}
		imp := ImportPath(newImportPath) // TODO(adonovan): what if newImportPath has vendor/ prefix?
		if err := renameImports(ctx, s, mp, imp, pkgName, renamingEdits); err != nil {
			return err
		}
	}

	return nil
}

// renamePackageClause computes edits renaming the package clause of files in
// the package described by the given metadata, to newName.
//
// Edits are written into the edits map.
func renamePackageClause(ctx context.Context, mp *metadata.Package, snapshot *cache.Snapshot, newName PackageName, edits map[protocol.DocumentURI][]diff.Edit) error {
	// Rename internal references to the package in the renaming package.
	for _, uri := range mp.CompiledGoFiles {
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return err
		}
		f, err := snapshot.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			return err
		}
		if f.File.Name == nil {
			continue // no package declaration
		}

		edit, err := posEdit(f.Tok, f.File.Name.Pos(), f.File.Name.End(), string(newName))
		if err != nil {
			return err
		}
		edits[f.URI] = append(edits[f.URI], edit)
	}

	return nil
}

// renameImports computes the set of edits to imports resulting from renaming
// the package described by the given metadata, to a package with import path
// newPath and name newName.
//
// Edits are written into the edits map.
func renameImports(ctx context.Context, snapshot *cache.Snapshot, mp *metadata.Package, newPath ImportPath, newName PackageName, allEdits map[protocol.DocumentURI][]diff.Edit) error {
	rdeps, err := snapshot.ReverseDependencies(ctx, mp.ID, false) // find direct importers
	if err != nil {
		return err
	}

	// Pass 1: rename import paths in import declarations.
	needsTypeCheck := make(map[PackageID][]protocol.DocumentURI)
	for _, rdep := range rdeps {
		if rdep.IsIntermediateTestVariant() {
			continue // for renaming, these variants are redundant
		}

		for _, uri := range rdep.CompiledGoFiles {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return err
			}
			f, err := snapshot.ParseGo(ctx, fh, parsego.Header)
			if err != nil {
				return err
			}
			if f.File.Name == nil {
				continue // no package declaration
			}
			for _, imp := range f.File.Imports {
				if rdep.DepsByImpPath[metadata.UnquoteImportPath(imp)] != mp.ID {
					continue // not the import we're looking for
				}

				// If we are moving a package from a non-internal directory to
				// an internal directory, and there is an importer located in a
				// different module, then it is an invalid import.
				//
				// We do not prevent moves from an internal directory to a
				// non-internal directory.
				if !metadata.IsValidImport(rdep.PkgPath, metadata.PackagePath(newPath), snapshot.View().Type() != cache.GoPackagesDriverView) {
					return fmt.Errorf("invalid: package move would result in illegal internal import")
				}

				// If the import does not explicitly specify
				// a local name, then we need to invoke the
				// type checker to locate references to update.
				//
				// TODO(adonovan): is this actually true?
				// Renaming an import with a local name can still
				// cause conflicts: shadowing of built-ins, or of
				// package-level decls in the same or another file.
				if imp.Name == nil {
					needsTypeCheck[rdep.ID] = append(needsTypeCheck[rdep.ID], uri)
				}

				// Create text edit for the import path (string literal).
				edit, err := posEdit(f.Tok, imp.Path.Pos(), imp.Path.End(), strconv.Quote(string(newPath)))
				if err != nil {
					return err
				}
				allEdits[uri] = append(allEdits[uri], edit)
			}
		}
	}

	// If the imported package's name hasn't changed,
	// we don't need to rename references within each file.
	if newName == mp.Name {
		return nil
	}

	// Pass 2: rename local name (types.PkgName) of imported
	// package throughout one or more files of the package.
	ids := make([]PackageID, 0, len(needsTypeCheck))
	for id := range needsTypeCheck {
		ids = append(ids, id)
	}
	pkgs, err := snapshot.TypeCheck(ctx, ids...)
	if err != nil {
		return err
	}
	for i, id := range ids {
		pkg := pkgs[i]
		for _, uri := range needsTypeCheck[id] {
			f, err := pkg.File(uri)
			if err != nil {
				return err
			}
			for _, imp := range f.File.Imports {
				if imp.Name != nil {
					continue // has explicit local name
				}
				if rdeps[id].DepsByImpPath[metadata.UnquoteImportPath(imp)] != mp.ID {
					continue // not the import we're looking for
				}

				pkgname, ok := pkg.TypesInfo().Implicits[imp].(*types.PkgName)
				if !ok {
					// "can't happen", but be defensive (#71656)
					return fmt.Errorf("internal error: missing type information for %s import at %s",
						imp.Path.Value, safetoken.StartPosition(pkg.FileSet(), imp.Pos()))
				}

				pkgScope := pkg.Types().Scope()
				fileScope := pkg.TypesInfo().Scopes[f.File]

				localName := string(newName)
				try := 0

				// Keep trying with fresh names until one succeeds.
				//
				// TODO(adonovan): fix: this loop is not sufficient to choose a name
				// that is guaranteed to be conflict-free; renameObj may still fail.
				// So the retry loop should be around renameObj, and we shouldn't
				// bother with scopes here.
				for fileScope.Lookup(localName) != nil || pkgScope.Lookup(localName) != nil {
					try++
					localName = fmt.Sprintf("%s%d", newName, try)
				}

				// renameObj detects various conflicts, including:
				// - new name conflicts with a package-level decl in this file;
				// - new name hides a package-level decl in another file that
				//   is actually referenced in this file;
				// - new name hides a built-in that is actually referenced
				//   in this file;
				// - a reference in this file to the old package name would
				//   become shadowed by an intervening declaration that
				//   uses the new name.
				// It returns the edits if no conflict was detected.
				editMap, _, err := renameObjects(localName, pkg, pkgname)
				if err != nil {
					return err
				}

				// If the chosen local package name matches the package's
				// new name, delete the change that would have inserted
				// an explicit local name, which is always the lexically
				// first change.
				if localName == string(newName) {
					edits, ok := editMap[uri]
					if !ok {
						return fmt.Errorf("internal error: no changes for %s", uri)
					}
					diff.SortEdits(edits)
					editMap[uri] = edits[1:]
				}
				for uri, edits := range editMap {
					allEdits[uri] = append(allEdits[uri], edits...)
				}
			}
		}
	}
	return nil
}

// renameObjects computes the edits to the type-checked syntax package pkg
// required to rename a set of target objects to newName.
//
// It also returns the set of objects that were found (due to
// corresponding methods and embedded fields) to require renaming as a
// consequence of the requested renamings.
//
// It returns an error if the renaming would cause a conflict.
func renameObjects(newName string, pkg *cache.Package, targets ...types.Object) (map[protocol.DocumentURI][]diff.Edit, map[types.Object]bool, error) {
	r := renamer{
		pkg:          pkg,
		objsToUpdate: make(map[types.Object]bool),
		from:         targets[0].Name(),
		to:           newName,
	}

	// A renaming initiated at an interface method indicates the
	// intention to rename abstract and concrete methods as needed
	// to preserve assignability.
	// TODO(adonovan): pull this into the caller.
	for _, obj := range targets {
		if obj, ok := obj.(*types.Func); ok {
			recv := obj.Signature().Recv()
			if recv != nil && types.IsInterface(recv.Type().Underlying()) {
				r.changeMethods = true
				break
			}
		}
	}

	// Check that the renaming of the identifier is ok.
	for _, obj := range targets {
		r.check(obj)
		if len(r.conflicts) > 0 {
			// Stop at first error.
			return nil, nil, fmt.Errorf("%s", strings.Join(r.conflicts, "\n"))
		}
	}

	editMap, err := r.update()
	if err != nil {
		return nil, nil, err
	}

	// Remove initial targets so that only 'consequences' remain.
	for _, obj := range targets {
		delete(r.objsToUpdate, obj)
	}
	return editMap, r.objsToUpdate, nil
}

// Rename all references to the target objects.
func (r *renamer) update() (map[protocol.DocumentURI][]diff.Edit, error) {
	result := make(map[protocol.DocumentURI][]diff.Edit)

	// shouldUpdate reports whether obj is one of (or an
	// instantiation of one of) the target objects.
	shouldUpdate := func(obj types.Object) bool {
		return containsOrigin(r.objsToUpdate, obj)
	}

	// Find all identifiers in the package that define or use a
	// renamed object. We iterate over info as it is more efficient
	// than calling ast.Inspect for each of r.pkg.CompiledGoFiles().
	type item struct {
		node  ast.Node // Ident, ImportSpec (obj=PkgName), or CaseClause (obj=Var)
		obj   types.Object
		isDef bool
	}
	var items []item
	info := r.pkg.TypesInfo()
	for id, obj := range info.Uses {
		if shouldUpdate(obj) {
			items = append(items, item{id, obj, false})
		}
	}
	for id, obj := range info.Defs {
		if shouldUpdate(obj) {
			items = append(items, item{id, obj, true})
		}
	}
	for node, obj := range info.Implicits {
		if shouldUpdate(obj) {
			switch node.(type) {
			case *ast.ImportSpec, *ast.CaseClause:
				items = append(items, item{node, obj, true})
			}
		}
	}
	sort.Slice(items, func(i, j int) bool {
		return items[i].node.Pos() < items[j].node.Pos()
	})

	// Update each identifier, and its doc comment if it is a declaration.
	for _, item := range items {
		pgf, err := r.pkg.FileEnclosing(item.node.Pos())
		if err != nil {
			bug.Reportf("edit does not belong to syntax of package %q: %v", r.pkg, err)
			continue
		}

		// Renaming a types.PkgName may result in the addition or removal of an identifier,
		// so we deal with this separately.
		if pkgName, ok := item.obj.(*types.PkgName); ok && item.isDef {
			edit, err := r.updatePkgName(pgf, pkgName)
			if err != nil {
				return nil, err
			}
			result[pgf.URI] = append(result[pgf.URI], edit)
			continue
		}

		// Workaround the unfortunate lack of a Var object
		// for x in "switch x := expr.(type) {}" by adjusting
		// the case clause to the switch ident.
		// This may result in duplicate edits, but we de-dup later.
		if _, ok := item.node.(*ast.CaseClause); ok {
			path, _ := goastutil.PathEnclosingInterval(pgf.File, item.obj.Pos(), item.obj.Pos())
			item.node = path[0].(*ast.Ident)
		}

		// Replace the identifier with r.to.
		edit, err := posEdit(pgf.Tok, item.node.Pos(), item.node.End(), r.to)
		if err != nil {
			return nil, err
		}

		result[pgf.URI] = append(result[pgf.URI], edit)

		if !item.isDef { // uses do not have doc comments to update.
			continue
		}

		cur, _ := pgf.Cursor().FindNode(item.node) // can't fail
		doc := docComment(pgf, cur)
		if doc == nil {
			continue
		}

		// Perform the rename in doc comments declared in the original package.
		// go/parser strips out \r\n returns from the comment text, so go
		// line-by-line through the comment text to get the correct positions.
		docRegexp := regexp.MustCompile(`\b` + r.from + `\b`) // valid identifier => valid regexp
		for _, comment := range doc.List {
			if isDirective(comment.Text) {
				continue
			}
			// TODO(adonovan): why are we looping over lines?
			// Just run the loop body once over the entire multiline comment.
			lines := strings.Split(comment.Text, "\n")
			tokFile := pgf.Tok
			commentLine := safetoken.Line(tokFile, comment.Pos())
			uri := protocol.URIFromPath(tokFile.Name())
			for i, line := range lines {
				lineStart := comment.Pos()
				if i > 0 {
					lineStart = tokFile.LineStart(commentLine + i)
				}
				for _, locs := range docRegexp.FindAllIndex([]byte(line), -1) {
					edit, err := posEdit(tokFile, lineStart+token.Pos(locs[0]), lineStart+token.Pos(locs[1]), r.to)
					if err != nil {
						return nil, err // can't happen
					}
					result[uri] = append(result[uri], edit)
				}
			}
		}
	}

	docLinkEdits, err := r.updateCommentDocLinks()
	if err != nil {
		return nil, err
	}
	for uri, edits := range docLinkEdits {
		result[uri] = append(result[uri], edits...)
	}

	return result, nil
}

// updateCommentDocLinks updates each doc comment in the package
// that refers to one of the renamed objects using a doc link
// (https://golang.org/doc/comment#doclinks) such as "[pkg.Type.Method]".
func (r *renamer) updateCommentDocLinks() (map[protocol.DocumentURI][]diff.Edit, error) {
	result := make(map[protocol.DocumentURI][]diff.Edit)
	var docRenamers []*docLinkRenamer
	for obj := range r.objsToUpdate {
		if _, ok := obj.(*types.PkgName); ok {
			// The dot package name will not be referenced
			if obj.Name() == "." {
				continue
			}

			docRenamers = append(docRenamers, &docLinkRenamer{
				isDep:       false,
				isPkgOrType: true,
				file:        r.pkg.FileSet().File(obj.Pos()),
				regexp:      docLinkPattern("", "", obj.Name(), true),
				to:          r.to,
			})
			continue
		}
		if !obj.Exported() {
			continue
		}
		recvName := ""
		// Doc links can reference only exported package-level objects
		// and methods of exported package-level named types.
		if !typesinternal.IsPackageLevel(obj) {
			obj, isFunc := obj.(*types.Func)
			if !isFunc {
				continue
			}
			recv := obj.Signature().Recv()
			if recv == nil {
				continue
			}
			_, named := typesinternal.ReceiverNamed(recv)
			if named == nil {
				continue
			}
			// Doc links can't reference interface methods.
			if types.IsInterface(named.Underlying()) {
				continue
			}
			name := named.Origin().Obj()
			if !name.Exported() || !typesinternal.IsPackageLevel(name) {
				continue
			}
			recvName = name.Name()
		}

		// Qualify objects from other packages.
		pkgName := ""
		if r.pkg.Types() != obj.Pkg() {
			pkgName = obj.Pkg().Name()
		}
		_, isTypeName := obj.(*types.TypeName)
		docRenamers = append(docRenamers, &docLinkRenamer{
			isDep:       r.pkg.Types() != obj.Pkg(),
			isPkgOrType: isTypeName,
			packagePath: obj.Pkg().Path(),
			packageName: pkgName,
			recvName:    recvName,
			objName:     obj.Name(),
			regexp:      docLinkPattern(pkgName, recvName, obj.Name(), isTypeName),
			to:          r.to,
		})
	}
	for _, pgf := range r.pkg.CompiledGoFiles() {
		for _, d := range docRenamers {
			edits, err := d.update(pgf)
			if err != nil {
				return nil, err
			}
			if len(edits) > 0 {
				result[pgf.URI] = append(result[pgf.URI], edits...)
			}
		}
	}
	return result, nil
}

// docLinkPattern returns a regular expression that matches doclinks in comments.
// It has one submatch that indicates the symbol to be updated.
func docLinkPattern(pkgName, recvName, objName string, isPkgOrType bool) *regexp.Regexp {
	// The doc link may contain a leading star, e.g. [*bytes.Buffer].
	pattern := `\[\*?`
	if pkgName != "" {
		pattern += pkgName + `\.`
	}
	if recvName != "" {
		pattern += recvName + `\.`
	}
	// The first submatch is object name.
	pattern += `(` + objName + `)`
	// If the object is a *types.TypeName or *types.PkgName, also need
	// match the objects referenced by them, so add `(\.\w+)*`.
	if isPkgOrType {
		pattern += `(?:\.\w+)*`
	}
	// There are two type of link in comments:
	//   1. url link. e.g. [text]: url
	//   2. doc link. e.g. [pkg.Name]
	// in order to only match the doc link, add `([^:]|$)` in the end.
	pattern += `\](?:[^:]|$)`

	return regexp.MustCompile(pattern)
}

// A docLinkRenamer renames doc links of forms such as these:
//
//	[Func]
//	[pkg.Func]
//	[RecvType.Method]
//	[*Type]
//	[*pkg.Type]
//	[*pkg.RecvType.Method]
type docLinkRenamer struct {
	isDep       bool // object is from a dependency package
	isPkgOrType bool // object is *types.PkgName or *types.TypeName
	packagePath string
	packageName string // e.g. "pkg"
	recvName    string // e.g. "RecvType"
	objName     string // e.g. "Func", "Type", "Method"
	to          string // new name
	regexp      *regexp.Regexp

	file *token.File // enclosing file, if renaming *types.PkgName
}

// update updates doc links in the package level comments.
func (r *docLinkRenamer) update(pgf *parsego.File) (result []diff.Edit, err error) {
	if r.file != nil && r.file != pgf.Tok {
		return nil, nil
	}
	pattern := r.regexp
	// If the object is in dependency package,
	// the imported name in the file may be different from the original package name
	if r.isDep {
		for _, spec := range pgf.File.Imports {
			importPath, _ := strconv.Unquote(spec.Path.Value)
			if importPath == r.packagePath {
				// Ignore blank imports
				if spec.Name == nil || spec.Name.Name == "_" || spec.Name.Name == "." {
					continue
				}
				if spec.Name.Name != r.packageName {
					pattern = docLinkPattern(spec.Name.Name, r.recvName, r.objName, r.isPkgOrType)
				}
				break
			}
		}
	}

	var edits []diff.Edit
	updateDocLinks := func(doc *ast.CommentGroup) error {
		if doc != nil {
			for _, c := range doc.List {
				for _, locs := range pattern.FindAllStringSubmatchIndex(c.Text, -1) {
					// The first submatch is the object name, so the locs[2:4] is the index of object name.
					edit, err := posEdit(pgf.Tok, c.Pos()+token.Pos(locs[2]), c.Pos()+token.Pos(locs[3]), r.to)
					if err != nil {
						return err
					}
					edits = append(edits, edit)
				}
			}
		}
		return nil
	}

	// Update package doc comments.
	err = updateDocLinks(pgf.File.Doc)
	if err != nil {
		return nil, err
	}
	for _, decl := range pgf.File.Decls {
		var doc *ast.CommentGroup
		switch decl := decl.(type) {
		case *ast.GenDecl:
			doc = decl.Doc
		case *ast.FuncDecl:
			doc = decl.Doc
		}
		err = updateDocLinks(doc)
		if err != nil {
			return nil, err
		}
	}
	return edits, nil
}

// docComment returns the doc for an identifier within the specified file.
func docComment(pgf *parsego.File, curId inspector.Cursor) *ast.CommentGroup {
	// (Strictly it needn't be an identifier; only its Pos is used.)
	id := curId.Node().(*ast.Ident)
	for cur := range curId.Enclosing() {
		switch decl := cur.Node().(type) {
		case *ast.FuncDecl:
			return decl.Doc
		case *ast.Field:
			return decl.Doc
		case *ast.GenDecl:
			return decl.Doc
		// For {Type,Value}Spec, if the doc on the spec is absent,
		// search for the enclosing GenDecl
		case *ast.TypeSpec:
			if decl.Doc != nil {
				return decl.Doc
			}
		case *ast.ValueSpec:
			if decl.Doc != nil {
				return decl.Doc
			}
		case *ast.Ident:
		case *ast.AssignStmt:
			// *ast.AssignStmt doesn't have an associated comment group.
			// So, we try to find a comment just before the identifier.

			// Try to find a comment group only for short variable declarations (:=).
			if decl.Tok != token.DEFINE {
				return nil
			}

			identLine := safetoken.Line(pgf.Tok, id.Pos())
			for _, comment := range pgf.File.Comments {
				if comment.Pos() > id.Pos() {
					// Comment is after the identifier.
					continue
				}

				lastCommentLine := safetoken.Line(pgf.Tok, comment.End())
				if lastCommentLine+1 == identLine {
					return comment
				}
			}
		default:
			return nil
		}
	}
	return nil
}

// docCommentPosToIdent returns a cursor for the identifier whose doc
// comment contains pos, if any. The pos must be within an occurrence
// of the identifier's name, otherwise it returns zero.
func docCommentPosToIdent(pgf *parsego.File, start, end token.Pos, cur inspector.Cursor) (inspector.Cursor, bool) {
	for curId := range cur.Preorder((*ast.Ident)(nil)) {
		id := curId.Node().(*ast.Ident)
		if start > id.Pos() {
			continue // Doc comments are not located after an ident.
		}
		doc := docComment(pgf, curId)
		if doc == nil || !(doc.Pos() <= start && end < doc.End()) {
			continue
		}

		docRegexp := regexp.MustCompile(`\b` + id.Name + `\b`)
		for _, comment := range doc.List {
			if isDirective(comment.Text) || !(comment.Pos() <= start && end < comment.End()) {
				continue
			}
			commentStart := comment.Pos()
			text, err := pgf.NodeText(comment)
			if err != nil {
				return inspector.Cursor{}, false
			}
			for _, locs := range docRegexp.FindAllIndex(text, -1) {
				matchStart := commentStart + token.Pos(locs[0])
				matchEnd := commentStart + token.Pos(locs[1])
				if matchStart <= start && end <= matchEnd {
					return curId, true
				}
			}
		}
	}
	return inspector.Cursor{}, false
}

// updatePkgName returns the updates to rename a pkgName in the import spec by
// only modifying the package name portion of the import declaration.
func (r *renamer) updatePkgName(pgf *parsego.File, pkgName *types.PkgName) (diff.Edit, error) {
	// Modify ImportSpec syntax to add or remove the Name as needed.
	path, _ := goastutil.PathEnclosingInterval(pgf.File, pkgName.Pos(), pkgName.Pos())
	if len(path) < 2 {
		return diff.Edit{}, fmt.Errorf("no path enclosing interval for %s", pkgName.Name())
	}
	spec, ok := path[1].(*ast.ImportSpec)
	if !ok {
		return diff.Edit{}, fmt.Errorf("failed to update PkgName for %s", pkgName.Name())
	}

	newText := ""
	if pkgName.Imported().Name() != r.to {
		newText = r.to + " "
	}

	// Replace the portion (possibly empty) of the spec before the path:
	//     local "path"      or      "path"
	//   ->      <-                -><-
	return posEdit(pgf.Tok, spec.Pos(), spec.Path.Pos(), newText)
}

// parsePackageNameDecl is a convenience function that parses and
// returns the package name declaration of file fh, and reports
// whether the position ppos lies within it.
//
// Note: also used by references.
func parsePackageNameDecl(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) (*parsego.File, bool, error) {
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
	if err != nil {
		return nil, false, err
	}
	// Careful: because we used parsego.Header,
	// pgf.Pos(ppos) may be beyond EOF => (0, err).
	start, end, _ := pgf.RangePos(rng)
	return pgf, astutil.NodeContains(pgf.File.Name, astutil.RangeOf(start, end)), nil
}

// posEdit returns an edit to replace the (start, end) range of tf with 'new'.
func posEdit(tf *token.File, start, end token.Pos, new string) (diff.Edit, error) {
	startOffset, endOffset, err := safetoken.Offsets(tf, start, end)
	if err != nil {
		return diff.Edit{}, err
	}
	return diff.Edit{Start: startOffset, End: endOffset, New: new}, nil
}


================================================
FILE: gopls/internal/golang/rename_check.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//
// Taken from golang.org/x/tools/refactor/rename.

package golang

// This file defines the conflict-checking portion of the rename operation.
//
// The renamer works on a single package of type-checked syntax, and
// is called in parallel for all necessary packages in the workspace,
// possibly up to the transitive reverse dependencies of the
// declaration. Finally the union of all edits and errors is computed.
//
// Renaming one object may entail renaming of others. For example:
//
// - An embedded field couples a Var (field) and a TypeName.
//   So, renaming either one requires renaming the other.
//   If the initial object is an embedded field, we must add its
//   TypeName (and its enclosing package) to the renaming set;
//   this is easily discovered at the outset.
//
//   Conversely, if the initial object is a TypeName, we must observe
//   whether any of its references (from directly importing packages)
//   is coincident with an embedded field Var and, if so, initiate a
//   renaming of it.
//
// - A method of an interface type is coupled to all corresponding
//   methods of types that are assigned to the interface (as
//   discovered by the 'satisfy' pass). As a matter of usability, we
//   require that such renamings be initiated from the interface
//   method, not the concrete method.

import (
	"errors"
	"fmt"
	"go/ast"
	"go/build"
	"go/token"
	"go/types"
	"io/fs"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"unicode"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/refactor/satisfy"
)

// errorf reports an error (e.g. conflict) and prevents file modification.
func (r *renamer) errorf(pos token.Pos, format string, args ...any) {
	// Conflict error messages in the old gorename tool (whence this
	// logic originated) contain rich information associated with
	// multiple source lines, such as:
	//
	//   p/a.go:1:2: renaming "x" to "y" here
	//   p/b.go:3:4: \t would cause this reference to "y"
	//   p/c.go:5:5: \t to become shadowed by this intervening declaration.
	//
	// Unfortunately LSP provides no means to transmit the
	// structure of this error, so we format the positions briefly
	// using dir/file.go where dir is the base name of the parent
	// directory.

	var conflict strings.Builder

	// Add prefix of (truncated) position.
	if pos != token.NoPos {
		// TODO(adonovan): skip position of first error if it is
		// on the same line as the renaming itself.
		posn := safetoken.StartPosition(r.pkg.FileSet(), pos).String()
		segments := strings.Split(filepath.ToSlash(posn), "/")
		if n := len(segments); n > 2 {
			segments = segments[n-2:]
		}
		posn = strings.Join(segments, "/")
		fmt.Fprintf(&conflict, "%s:", posn)

		if !strings.HasPrefix(format, "\t") {
			conflict.WriteByte(' ')
		}
	}

	fmt.Fprintf(&conflict, format, args...)
	r.conflicts = append(r.conflicts, conflict.String())
}

// check performs safety checks of the renaming of the 'from' object to r.to.
func (r *renamer) check(from types.Object) {
	if r.objsToUpdate[from] {
		return
	}
	r.objsToUpdate[from] = true

	// NB: order of conditions is important.
	if from_, ok := from.(*types.PkgName); ok {
		r.checkInFileBlock(from_)
	} else if from_, ok := from.(*types.Label); ok {
		r.checkLabel(from_)
	} else if typesinternal.IsPackageLevel(from) {
		r.checkInPackageBlock(from)
	} else if v, ok := from.(*types.Var); ok && v.IsField() {
		r.checkStructField(v)
	} else if f, ok := from.(*types.Func); ok && recv(f) != nil {
		r.checkMethod(f)
	} else if isLocal(from) {
		r.checkInLexicalScope(from)
	} else {
		r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n",
			objectKind(from), from)
	}
}

// checkInFileBlock performs safety checks for renames of objects in the file block,
// i.e. imported package names.
func (r *renamer) checkInFileBlock(from *types.PkgName) {
	// Check import name is not "init".
	if r.to == "init" {
		r.errorf(from.Pos(), "%q is not a valid imported package name", r.to)
	}

	// Check for conflicts between file and package block.
	if prev := from.Pkg().Scope().Lookup(r.to); prev != nil {
		r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
			objectKind(from), from.Name(), r.to)
		r.errorf(prev.Pos(), "\twith this package member %s",
			objectKind(prev))
		return // since checkInPackageBlock would report redundant errors
	}

	// Check for conflicts in lexical scope.
	r.checkInLexicalScope(from)
}

// checkInPackageBlock performs safety checks for renames of
// func/var/const/type objects in the package block.
func (r *renamer) checkInPackageBlock(from types.Object) {
	// Check that there are no references to the name from another
	// package if the renaming would make it unexported.
	if typ := r.pkg.Types(); typ != from.Pkg() && ast.IsExported(r.from) && !ast.IsExported(r.to) {
		if id := someUse(r.pkg.TypesInfo(), from); id != nil {
			r.checkExport(id, typ, from)
		}
	}

	// Check that in the package block, "init" is a function, and never referenced.
	if r.to == "init" {
		kind := objectKind(from)
		if kind == "func" {
			// Reject if intra-package references to it exist.
			for id, obj := range r.pkg.TypesInfo().Uses {
				if obj == from {
					r.errorf(from.Pos(),
						"renaming this func %q to %q would make it a package initializer",
						from.Name(), r.to)
					r.errorf(id.Pos(), "\tbut references to it exist")
					break
				}
			}
		} else {
			r.errorf(from.Pos(), "you cannot have a %s at package level named %q",
				kind, r.to)
		}
	}

	// In the declaring package, check for conflicts between the
	// package block and all file blocks.
	if from.Pkg() == r.pkg.Types() {
		for _, f := range r.pkg.Syntax() {
			fileScope := r.pkg.TypesInfo().Scopes[f]
			if fileScope == nil {
				continue // type error? (golang/go#40835)
			}
			b, prev := fileScope.LookupParent(r.to, token.NoPos)
			if b == fileScope {
				r.errorf(from.Pos(), "renaming this %s %q to %q would conflict", objectKind(from), from.Name(), r.to)
				r.errorf(prev.Pos(), "\twith this %s", objectKind(prev))
				return // since checkInPackageBlock would report redundant errors
			}
		}
	}

	// Check for conflicts in lexical scope.
	r.checkInLexicalScope(from)
}

// checkInLexicalScope performs safety checks that a renaming does not
// change the lexical reference structure of the specified package.
//
// For objects in lexical scope, there are three kinds of conflicts:
// same-, sub-, and super-block conflicts.  We will illustrate all three
// using this example:
//
//	var x int
//	var z int
//
//	func f(y int) {
//		print(x)
//		print(y)
//	}
//
// Renaming x to z encounters a "same-block conflict", because an object
// with the new name already exists, defined in the same lexical block
// as the old object.
//
// Renaming x to y encounters a "sub-block conflict", because there exists
// a reference to x from within (what would become) a hole in its scope.
// The definition of y in an (inner) sub-block would cast a shadow in
// the scope of the renamed variable.
//
// Renaming y to x encounters a "super-block conflict".  This is the
// converse situation: there is an existing definition of the new name
// (x) in an (enclosing) super-block, and the renaming would create a
// hole in its scope, within which there exist references to it.  The
// new name shadows the existing definition of x in the super-block.
//
// Removing the old name (and all references to it) is always safe, and
// requires no checks.
func (r *renamer) checkInLexicalScope(from types.Object) {
	b := from.Parent() // the block defining the 'from' object
	if b != nil {
		toBlock, to := b.LookupParent(r.to, from.Parent().End())
		if toBlock == b {
			// same-block conflict
			r.errorf(from.Pos(), "renaming this %s %q to %q",
				objectKind(from), from.Name(), r.to)
			r.errorf(to.Pos(), "\tconflicts with %s in same block",
				objectKind(to))
			return
		} else if toBlock != nil {
			// Check for super-block conflict.
			// The name r.to is defined in a superblock.
			// Is that name referenced from within this block?
			forEachLexicalRef(r.pkg, to, func(id *ast.Ident, block *types.Scope) bool {
				_, obj := block.LookupParent(from.Name(), id.Pos())
				if obj == from {
					// super-block conflict
					r.errorf(from.Pos(), "renaming this %s %q to %q",
						objectKind(from), from.Name(), r.to)
					r.errorf(id.Pos(), "\twould shadow this reference")
					r.errorf(to.Pos(), "\tto the %s declared here",
						objectKind(to))
					return false // stop
				}
				return true
			})
		}
	}
	// Check for sub-block conflict.
	// Is there an intervening definition of r.to between
	// the block defining 'from' and some reference to it?
	forEachLexicalRef(r.pkg, from, func(id *ast.Ident, block *types.Scope) bool {
		// Find the block that defines the found reference.
		// It may be an ancestor.
		fromBlock, _ := block.LookupParent(from.Name(), id.Pos())
		// See what r.to would resolve to in the same scope.
		toBlock, to := block.LookupParent(r.to, id.Pos())
		if to != nil {
			// sub-block conflict
			if deeper(toBlock, fromBlock) {
				r.errorf(from.Pos(), "renaming this %s %q to %q",
					objectKind(from), from.Name(), r.to)
				r.errorf(id.Pos(), "\twould cause this reference to become shadowed")
				r.errorf(to.Pos(), "\tby this intervening %s definition",
					objectKind(to))
				return false // stop
			}
		}
		return true
	})

	// Renaming a type that is used as an embedded field
	// requires renaming the field too. e.g.
	// 	type T int // if we rename this to U..
	// 	var s struct {T}
	// 	print(s.T) // ...this must change too
	if _, ok := from.(*types.TypeName); ok {
		for id, obj := range r.pkg.TypesInfo().Uses {
			if obj == from {
				if field := r.pkg.TypesInfo().Defs[id]; field != nil {
					r.check(field)
				}
			}
		}
	}
}

// deeper reports whether block x is lexically deeper than y.
func deeper(x, y *types.Scope) bool {
	if x == y || x == nil {
		return false
	} else if y == nil {
		return true
	} else {
		return deeper(x.Parent(), y.Parent())
	}
}

// Scope and Position
//
// Consider a function f declared as:
//
//	func f[T *U, U *T](p, q T) (r, s U) { var ( v T; w = v ); type (t *t; u t) }
//	^                                  ^           ^      ^         ^     ^
///   {T,U}                           {p,q,r,s}        v      w         t     u
//
// All objects {T, U, p, q, r, s, local} belong to the same lexical
// block, the function scope, which is found in types.Info.Scopes
// for f's FuncType. (A function body's BlockStmt does not have
// an associated scope; only nested BlockStmts do.)
//
// The effective scope of each object is different:
//
//   - The type parameters T and U, whose constraints may refer to each
//     other, all have a scope that starts at the beginning of the
//     FuncDecl.Type.Func token.
//
//   - The parameter and result variables {p,q,r,s} can reference the
//     type parameters but not each other, so their scopes all start at
//     the end of the FuncType.
//     (Prior to go1.22 it was--incorrectly--unset; see #64295).
//     Beware also that Scope.Innermost does not currently work correctly for
//     type parameters: it returns the scope of the package, not the function.
//
//   - Each const or var {v,w} declared within the function body has a
//     scope that begins at the end of its ValueSpec, or after the
//     AssignStmt for a var declared by ":=".
//
//   - Each type {t,u} in the body has a scope that begins at
//     the start of the TypeSpec, so they can be self-recursive
//     but--unlike package-level types--not mutually recursive.

// forEachLexicalRef calls fn(id, block) for each identifier id in package
// pkg that is a reference to obj in lexical scope.  block is the
// lexical block enclosing the reference.  If fn returns false the
// iteration is terminated and findLexicalRefs returns false.
func forEachLexicalRef(pkg *cache.Package, obj types.Object, fn func(id *ast.Ident, block *types.Scope) bool) bool {
	filter := []ast.Node{
		(*ast.Ident)(nil),
		(*ast.SelectorExpr)(nil),
		(*ast.CompositeLit)(nil),
	}
	ok := true
	var visit func(cur inspector.Cursor) (descend bool)
	visit = func(cur inspector.Cursor) (descend bool) {
		if !ok {
			return false // bail out
		}
		switch n := cur.Node().(type) {
		case *ast.Ident:
			if pkg.TypesInfo().Uses[n] == obj {
				block := typesinternal.EnclosingScope(pkg.TypesInfo(), cur)
				if !fn(n, block) {
					ok = false
				}
			}

		case *ast.SelectorExpr:
			// don't visit n.Sel
			cur.ChildAt(edge.SelectorExpr_X, -1).Inspect(filter, visit)
			return false // don't descend

		case *ast.CompositeLit:
			// Handle recursion ourselves for struct literals
			// so we don't visit field identifiers.
			tv, ok := pkg.TypesInfo().Types[n]
			if !ok {
				return false // don't descend
			}
			if is[*types.Struct](typeparams.CoreType(typeparams.Deref(tv.Type))) {
				if n.Type != nil {
					cur.ChildAt(edge.CompositeLit_Type, -1).Inspect(filter, visit)
				}
				for i, elt := range n.Elts {
					curElt := cur.ChildAt(edge.CompositeLit_Elts, i)
					if _, ok := elt.(*ast.KeyValueExpr); ok {
						// skip kv.Key
						curElt = curElt.ChildAt(edge.KeyValueExpr_Value, -1)
					}
					curElt.Inspect(filter, visit)
				}
				return false // don't descend
			}
		}
		return true
	}

	for _, pgf := range pkg.CompiledGoFiles() {
		pgf.Cursor().Inspect(filter, visit)
		if !ok {
			break
		}
	}
	return ok
}

func (r *renamer) checkLabel(label *types.Label) {
	// Check there are no identical labels in the function's label block.
	// (Label blocks don't nest, so this is easy.)
	if prev := label.Parent().Lookup(r.to); prev != nil {
		r.errorf(label.Pos(), "renaming this label %q to %q", label.Name(), prev.Name())
		r.errorf(prev.Pos(), "\twould conflict with this one")
	}
}

// checkStructField checks that the field renaming will not cause
// conflicts at its declaration, or ambiguity or changes to any selection.
func (r *renamer) checkStructField(from *types.Var) {
	// If this is the declaring package, check that the struct
	// declaration is free of field conflicts, and field/method
	// conflicts.
	//
	// go/types offers no easy way to get from a field (or interface
	// method) to its declaring struct (or interface), so we must
	// ascend the AST.
	if pgf, err := r.pkg.FileEnclosing(from.Pos()); err == nil {
		path, _ := astutil.PathEnclosingInterval(pgf.File, from.Pos(), from.Pos())
		// path matches this pattern:
		// [Ident SelectorExpr? StarExpr? Field FieldList StructType ParenExpr* ... File]

		// Ascend to FieldList.
		var i int
		for {
			if _, ok := path[i].(*ast.FieldList); ok {
				break
			}
			i++
		}
		i++
		tStruct := path[i].(*ast.StructType)
		i++
		// Ascend past parens (unlikely).
		for {
			_, ok := path[i].(*ast.ParenExpr)
			if !ok {
				break
			}
			i++
		}
		if spec, ok := path[i].(*ast.TypeSpec); ok {
			// This struct is also a named type.
			// We must check for direct (non-promoted) field/field
			// and method/field conflicts.
			if tname := r.pkg.TypesInfo().Defs[spec.Name]; tname != nil {
				prev, indices, _ := types.LookupFieldOrMethod(tname.Type(), true, r.pkg.Types(), r.to)
				if len(indices) == 1 {
					r.errorf(from.Pos(), "renaming this field %q to %q",
						from.Name(), r.to)
					r.errorf(prev.Pos(), "\twould conflict with this %s",
						objectKind(prev))
					return // skip checkSelections to avoid redundant errors
				}
			}
		} else {
			// This struct is not a named type.
			// We need only check for direct (non-promoted) field/field conflicts.
			T := r.pkg.TypesInfo().Types[tStruct].Type.Underlying().(*types.Struct)
			for prev := range T.Fields() {
				if prev.Name() == r.to {
					r.errorf(from.Pos(), "renaming this field %q to %q",
						from.Name(), r.to)
					r.errorf(prev.Pos(), "\twould conflict with this field")
					return // skip checkSelections to avoid redundant errors
				}
			}
		}
	}

	// Renaming an anonymous field requires renaming the type too. e.g.
	// 	print(s.T)       // if we rename T to U,
	// 	type T int       // this and
	// 	var s struct {T} // this must change too.
	if from.Anonymous() {
		if named, ok := from.Type().(*types.Named); ok {
			r.check(named.Obj())
		} else if named, ok := types.Unalias(typesinternal.Unpointer(from.Type())).(*types.Named); ok {
			r.check(named.Obj())
		}
	}

	// Check integrity of existing (field and method) selections.
	r.checkSelections(from)
}

// checkSelections checks that all uses and selections that resolve to
// the specified object would continue to do so after the renaming.
func (r *renamer) checkSelections(from types.Object) {
	pkg := r.pkg
	typ := pkg.Types()
	{
		if id := someUse(pkg.TypesInfo(), from); id != nil {
			if !r.checkExport(id, typ, from) {
				return
			}
		}

		for syntax, sel := range pkg.TypesInfo().Selections {
			// There may be extant selections of only the old
			// name or only the new name, so we must check both.
			// (If neither, the renaming is sound.)
			//
			// In both cases, we wish to compare the lengths
			// of the implicit field path (Selection.Index)
			// to see if the renaming would change it.
			//
			// If a selection that resolves to 'from', when renamed,
			// would yield a path of the same or shorter length,
			// this indicates ambiguity or a changed referent,
			// analogous to same- or sub-block lexical conflict.
			//
			// If a selection using the name 'to' would
			// yield a path of the same or shorter length,
			// this indicates ambiguity or shadowing,
			// analogous to same- or super-block lexical conflict.

			// TODO(adonovan): fix: derive from Types[syntax.X].Mode
			// TODO(adonovan): test with pointer, value, addressable value.
			isAddressable := true

			if sel.Obj() == from {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil {
					// Renaming this existing selection of
					// 'from' may block access to an existing
					// type member named 'to'.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue // no ambiguity
					}
					r.selectionConflict(from, delta, syntax, obj)
					return
				}
			} else if sel.Obj().Name() == r.to {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from {
					// Renaming 'from' may cause this existing
					// selection of the name 'to' to change
					// its meaning.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue //  no ambiguity
					}
					r.selectionConflict(from, -delta, syntax, sel.Obj())
					return
				}
			}
		}
	}
}

func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) {
	r.errorf(from.Pos(), "renaming this %s %q to %q",
		objectKind(from), from.Name(), r.to)

	switch {
	case delta < 0:
		// analogous to sub-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould change the referent of this selection")
		r.errorf(obj.Pos(), "\tof this %s", objectKind(obj))
	case delta == 0:
		// analogous to same-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould make this reference ambiguous")
		r.errorf(obj.Pos(), "\twith this %s", objectKind(obj))
	case delta > 0:
		// analogous to super-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould shadow this selection")
		r.errorf(obj.Pos(), "\tof the %s declared here",
			objectKind(obj))
	}
}

// checkMethod performs safety checks for renaming a method.
// There are three hazards:
// - declaration conflicts
// - selection ambiguity/changes
// - entailed renamings of assignable concrete/interface types.
//
// We reject renamings initiated at concrete methods if it would
// change the assignability relation.  For renamings of abstract
// methods, we rename all methods transitively coupled to it via
// assignability.
func (r *renamer) checkMethod(from *types.Func) {
	// e.g. error.Error
	if from.Pkg() == nil {
		r.errorf(from.Pos(), "you cannot rename built-in method %s", from)
		return
	}

	// ASSIGNABILITY: We reject renamings of concrete methods that
	// would break a 'satisfy' constraint; but renamings of abstract
	// methods are allowed to proceed, and we rename affected
	// concrete and abstract methods as necessary.  It is the
	// initial method that determines the policy.

	// Check for conflict at point of declaration.
	// Check to ensure preservation of assignability requirements.
	R := recv(from).Type()
	if types.IsInterface(R) {
		// Abstract method

		// declaration
		prev, _, _ := types.LookupFieldOrMethod(R, false, from.Pkg(), r.to)
		if prev != nil {
			r.errorf(from.Pos(), "renaming this interface method %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this method")
			return
		}

		// Check all interfaces that embed this one for
		// declaration conflicts too.
		{
			// Start with named interface types (better errors)
			for _, obj := range r.pkg.TypesInfo().Defs {
				if obj, ok := obj.(*types.TypeName); ok && types.IsInterface(obj.Type()) {
					f, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), from.Name())
					if f == nil {
						continue
					}
					t, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), r.to)
					if t == nil {
						continue
					}
					r.errorf(from.Pos(), "renaming this interface method %q to %q",
						from.Name(), r.to)
					r.errorf(t.Pos(), "\twould conflict with this method")
					r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name())
				}
			}

			// Now look at all literal interface types (includes named ones again).
			for e, tv := range r.pkg.TypesInfo().Types {
				if e, ok := e.(*ast.InterfaceType); ok {
					_ = e
					_ = tv.Type.(*types.Interface)
					// TODO(adonovan): implement same check as above.
				}
			}
		}

		// assignability
		//
		// Find the set of concrete or abstract methods directly
		// coupled to abstract method 'from' by some
		// satisfy.Constraint, and rename them too.
		for key := range r.satisfy() {
			// key = (lhs, rhs) where lhs is always an interface.

			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
			if lsel == nil {
				continue
			}
			rmethods := r.msets.MethodSet(key.RHS)
			rsel := rmethods.Lookup(from.Pkg(), from.Name())
			if rsel == nil {
				continue
			}

			// If both sides have a method of this name,
			// and one of them is m, the other must be coupled.
			var coupled *types.Func
			switch from {
			case lsel.Obj():
				coupled = rsel.Obj().(*types.Func)
			case rsel.Obj():
				coupled = lsel.Obj().(*types.Func)
			default:
				continue
			}

			// We must treat concrete-to-interface
			// constraints like an implicit selection C.f of
			// each interface method I.f, and check that the
			// renaming leaves the selection unchanged and
			// unambiguous.
			//
			// Fun fact: the implicit selection of C.f
			// 	type I interface{f()}
			// 	type C struct{I}
			// 	func (C) g()
			//      var _ I = C{} // here
			// yields abstract method I.f.  This can make error
			// messages less than obvious.
			//
			if !types.IsInterface(key.RHS) {
				// The logic below was derived from checkSelections.

				rtosel := rmethods.Lookup(from.Pkg(), r.to)
				if rtosel != nil {
					rto := rtosel.Obj().(*types.Func)
					delta := len(rsel.Index()) - len(rtosel.Index())
					if delta < 0 {
						continue // no ambiguity
					}

					// TODO(adonovan): record the constraint's position.
					keyPos := token.NoPos

					r.errorf(from.Pos(), "renaming this method %q to %q",
						from.Name(), r.to)
					if delta == 0 {
						// analogous to same-block conflict
						r.errorf(keyPos, "\twould make the %s method of %s invoked via interface %s ambiguous",
							r.to, key.RHS, key.LHS)
						r.errorf(rto.Pos(), "\twith (%s).%s",
							recv(rto).Type(), r.to)
					} else {
						// analogous to super-block conflict
						r.errorf(keyPos, "\twould change the %s method of %s invoked via interface %s",
							r.to, key.RHS, key.LHS)
						r.errorf(coupled.Pos(), "\tfrom (%s).%s",
							recv(coupled).Type(), r.to)
						r.errorf(rto.Pos(), "\tto (%s).%s",
							recv(rto).Type(), r.to)
					}
					return // one error is enough
				}
			}

			if !r.changeMethods {
				// This should be unreachable.
				r.errorf(from.Pos(), "internal error: during renaming of abstract method %s", from)
				r.errorf(coupled.Pos(), "\tchangedMethods=false, coupled method=%s", coupled)
				r.errorf(from.Pos(), "\tPlease file a bug report")
				return
			}

			// Rename the coupled method to preserve assignability.
			r.check(coupled)
		}
	} else {
		// Concrete method

		// declaration
		prev, indices, _ := types.LookupFieldOrMethod(R, true, from.Pkg(), r.to)
		if prev != nil && len(indices) == 1 {
			r.errorf(from.Pos(), "renaming this method %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this %s",
				objectKind(prev))
			return
		}

		// assignability
		//
		// Find the set of abstract methods coupled to concrete
		// method 'from' by some satisfy.Constraint, and rename
		// them too.
		//
		// Coupling may be indirect, e.g. I.f <-> C.f via type D.
		//
		// 	type I interface {f()}
		//	type C int
		//	type (C) f()
		//	type D struct{C}
		//	var _ I = D{}
		//
		for key := range r.satisfy() {
			// key = (lhs, rhs) where lhs is always an interface.
			if types.IsInterface(key.RHS) {
				continue
			}
			rsel := r.msets.MethodSet(key.RHS).Lookup(from.Pkg(), from.Name())
			if rsel == nil || rsel.Obj() != from {
				continue // rhs does not have the method
			}
			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
			if lsel == nil {
				continue
			}
			imeth := lsel.Obj().(*types.Func)

			// imeth is the abstract method (e.g. I.f)
			// and key.RHS is the concrete coupling type (e.g. D).
			if !r.changeMethods {
				r.errorf(from.Pos(), "renaming this method %q to %q",
					from.Name(), r.to)
				var pos token.Pos
				var iface string

				I := recv(imeth).Type()
				if named, ok := types.Unalias(I).(*types.Named); ok {
					pos = named.Obj().Pos()
					iface = "interface " + named.Obj().Name()
				} else {
					pos = from.Pos()
					iface = I.String()
				}
				r.errorf(pos, "\twould make %s no longer assignable to %s",
					key.RHS, iface)
				r.errorf(imeth.Pos(), "\t(rename %s.%s if you intend to change both types)",
					I, from.Name())
				return // one error is enough
			}

			// Rename the coupled interface method to preserve assignability.
			r.check(imeth)
		}
	}

	// Check integrity of existing (field and method) selections.
	// We skip this if there were errors above, to avoid redundant errors.
	r.checkSelections(from)
}

func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool {
	// Reject cross-package references if r.to is unexported.
	// (Such references may be qualified identifiers or field/method
	// selections.)
	if !ast.IsExported(r.to) && pkg != from.Pkg() {
		r.errorf(from.Pos(),
			"renaming %q to %q would make it unexported",
			from.Name(), r.to)
		r.errorf(id.Pos(), "\tbreaking references from packages such as %q",
			pkg.Path())
		return false
	}
	return true
}

// satisfy returns the set of interface satisfaction constraints.
func (r *renamer) satisfy() map[satisfy.Constraint]bool {
	if r.satisfyConstraints == nil {
		// Compute on demand: it's expensive.
		var f satisfy.Finder
		pkg := r.pkg
		{
			// From satisfy.Finder documentation:
			//
			// The package must be free of type errors, and
			// info.{Defs,Uses,Selections,Types} must have been populated by the
			// type-checker.
			//
			// Only proceed if all packages have no errors.
			if len(pkg.ParseErrors()) > 0 || len(pkg.TypeErrors()) > 0 {
				var filename string
				if len(pkg.ParseErrors()) > 0 {
					err := pkg.ParseErrors()[0][0]
					filename = filepath.Base(err.Pos.Filename)
				} else if len(pkg.TypeErrors()) > 0 {
					err := pkg.TypeErrors()[0]
					filename = filepath.Base(err.Fset.File(err.Pos).Name())
				}
				r.errorf(token.NoPos, // we don't have a position for this error.
					"renaming %q to %q not possible because %q in %q has errors",
					r.from, r.to, filename, pkg.Metadata().PkgPath)
				return nil
			}
			f.Find(pkg.TypesInfo(), pkg.Syntax())
		}
		r.satisfyConstraints = f.Result
	}
	return r.satisfyConstraints
}

// -- helpers ----------------------------------------------------------

// recv returns the method's receiver.
func recv(meth *types.Func) *types.Var {
	return meth.Signature().Recv()
}

// someUse returns an arbitrary use of obj within info.
func someUse(info *types.Info, obj types.Object) *ast.Ident {
	for id, o := range info.Uses {
		if o == obj {
			return id
		}
	}
	return nil
}

func objectKind(obj types.Object) string {
	if obj == nil {
		return "nil object"
	}
	switch obj := obj.(type) {
	case *types.PkgName:
		return "imported package name"
	case *types.TypeName:
		return "type"
	case *types.Var:
		if obj.IsField() {
			return "field"
		}
	case *types.Func:
		if recv(obj) != nil {
			return "method"
		}
	}
	// label, func, var, const
	return strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
}

// NB: for renamings, blank is not considered valid.
func isValidIdentifier(id string) bool {
	if id == "" || id == "_" {
		return false
	}
	for i, r := range id {
		if !isLetter(r) && (i == 0 || !isDigit(r)) {
			return false
		}
	}
	return token.Lookup(id) == token.IDENT
}

// checkPackageRename returns the effective new package directory, path and name
// resulting from renaming the current package to newName, which may be an
// identifier or a package path. An error is returned if the renaming is
// invalid.
func checkPackageRename(curPkg *cache.Package, f file.Handle, newName string, moveSubpackages bool) (newPkgDir string, newPkgName PackageName, newPkgPath PackagePath, err error) {
	// Path unchanged
	if newName == curPkg.String() || newName == string(curPkg.Metadata().Name) {
		return f.URI().DirPath(), curPkg.Metadata().Name, curPkg.Metadata().PkgPath, nil
	}

	// If there are any Go files in the package that are not in the compiled package
	// with the current build config, we should not allow a package move.
	ignored := hasIgnoredGoFiles(curPkg)
	if ignored {
		return "", "", "", fmt.Errorf("moving a package with ignored files is not supported")
	}

	// TODO(mkalil): support relative paths
	if build.IsLocalImport(newName) {
		return "", "", "", fmt.Errorf("specifying relative paths in package rename not yet supported")
	}
	// When package move is enabled, we prompt with the full package path. Users
	// can either submit a full package path or just provide the package
	// identifier.
	validIdent := isValidIdentifier(newName)
	if validIdent {
		// Not an attempted move. Check if a directory already exists at that
		// path, in which case we should not allow renaming.
		root := filepath.Dir(f.URI().DirPath())
		newPkgDir = filepath.Join(root, newName)
		exists, empty, err := dirIsEmpty(newPkgDir)
		if err != nil {
			return "", "", "", err
		}
		// When rename moves subpackages, we merely change the directory name, which cannot
		// happen if the target directory already exists.
		if moveSubpackages && exists || !empty {
			return "", "", "", fmt.Errorf("invalid package identifier: %q is not empty", newPkgDir)
		}
		parentPkgPath := strings.TrimSuffix(string(curPkg.Metadata().PkgPath), string(curPkg.Metadata().Name)) // leaves a trailing slash
		newPkgPath = PackagePath(parentPkgPath + newName)
		newPkgName = PackageName(newName)
		return newPkgDir, newPkgName, newPkgPath, nil
	}
	// Don't allow moving packages across module boundaries.
	curModPath := curPkg.Metadata().Module.Path
	if !strings.HasPrefix(newName+"/", curModPath+"/") {
		return "", "", "", fmt.Errorf("invalid package path %q; cannot move package across module boundary", newName)
	}
	// Don't support package merging. If a directory already exists
	// at that path, we should not allow renaming.
	newPathAfterMod := strings.TrimPrefix(newName, curModPath) //newName is a package path here.
	modDir := curPkg.Metadata().Module.Dir
	newPkgDir = filepath.Join(modDir, filepath.FromSlash(newPathAfterMod))
	// Trim the starting slash, which is not considered valid in fs.ValidPath.
	isValidDir := fs.ValidPath(strings.TrimPrefix(newPkgDir, string(filepath.Separator)))
	if !isValidDir {
		return "", "", "", fmt.Errorf("invalid package path %q", newName)
	}
	newPkgName = PackageName(filepath.Base(newPkgDir))
	exists, empty, err := dirIsEmpty(newPkgDir)
	if err != nil {
		return "", "", "", err
	}
	// When rename moves subpackages, we merely change the directory name, which cannot
	// happen if the target directory already exists.
	if moveSubpackages && exists || !empty {
		return "", "", "", fmt.Errorf("invalid package path: %q is not empty", newPkgDir)
	}
	// Verify that the new package name is a valid identifier.
	if !isValidIdentifier(string(newPkgName)) {
		return "", "", "", fmt.Errorf("invalid package name %q", newPkgName)
	}
	if f.URI().Dir().Base() != string(curPkg.Metadata().Name) {
		return "", "", "", fmt.Errorf("can't move package: package name %q does not match directory base name %q", string(curPkg.Metadata().Name), f.URI().Dir().Base())
	}
	return newPkgDir, newPkgName, PackagePath(newName), nil
}

// hasIgnoredGoFiles returns true if the input pkg contains any Go files that
// are not part of package pkg with the current build configuration.
func hasIgnoredGoFiles(pkg *cache.Package) bool {
	// If any ignored files are Go files, don't allow a package move.
	for _, f := range pkg.Metadata().IgnoredFiles {
		if strings.HasSuffix(f.Path(), ".go") {
			return true
		}
	}
	return false
}

// dirIsEmpty returns two values: whether the directory exists and whether it is
// empty (contains only directory entries). If it does not exist, empty is
// always true.
func dirIsEmpty(dir string) (exists bool, empty bool, err error) {
	files, err := os.ReadDir(dir)
	if err != nil {
		if errors.Is(err, fs.ErrNotExist) {
			return false, true, nil
		} else {
			return false, false, err
		}
	}
	for _, f := range files {
		if !f.IsDir() {
			return true, false, nil
		}
	}
	return true, true, nil
}

// isLocal reports whether obj is local to some function.
// Precondition: not a struct field or interface method.
func isLocal(obj types.Object) bool {
	// [... 5=stmt 4=func 3=file 2=pkg 1=universe]
	var depth int
	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
		depth++
	}
	return depth >= 4
}

// -- Plundered from go/scanner: ---------------------------------------

func isLetter(ch rune) bool {
	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 0x80 && unicode.IsLetter(ch)
}

func isDigit(ch rune) bool {
	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
}


================================================
FILE: gopls/internal/golang/semtok.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

// This file defines the Semantic Tokens operation for Go source.

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"log"
	"path/filepath"
	"regexp"
	"slices"
	"strconv"
	"strings"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/fmtstr"
)

// semDebug enables comprehensive logging of decisions
// (gopls semtok foo.go > /dev/null shows log output).
// It should never be true in checked-in code.
const semDebug = false

func SemanticTokens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng *protocol.Range) (*protocol.SemanticTokens, error) {
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}

	// Select range.
	var start, end token.Pos
	if rng != nil {
		var err error
		start, end, err = pgf.RangePos(*rng)
		if err != nil {
			return nil, err // e.g. invalid range
		}
	} else {
		tok := pgf.Tok
		start, end = tok.Pos(0), tok.Pos(tok.Size()) // entire file
	}

	// Reject full semantic token requests for large files.
	//
	// The LSP says that errors for the semantic token requests
	// should only be returned for exceptions (a word not
	// otherwise defined). This code treats a too-large file as an
	// exception. On parse errors, the code does what it can.
	const maxFullFileSize = 100000
	if int(end-start) > maxFullFileSize {
		return nil, fmt.Errorf("semantic tokens: range %s too large (%d > %d)",
			fh.URI().Path(), end-start, maxFullFileSize)
	}

	tv := tokenVisitor{
		ctx:            ctx,
		metadataSource: snapshot,
		metadata:       pkg.Metadata(),
		info:           pkg.TypesInfo(),
		fset:           pkg.FileSet(),
		pkg:            pkg,
		pgf:            pgf,
		start:          start,
		end:            end,
	}
	tv.visit()
	return &protocol.SemanticTokens{
		Data: semtok.Encode(
			tv.tokens,
			snapshot.Options().EnabledSemanticTokenTypes(),
			snapshot.Options().EnabledSemanticTokenModifiers()),
		ResultID: time.Now().String(), // for delta requests, but we've never seen any
	}, nil
}

type tokenVisitor struct {
	// inputs
	ctx            context.Context // for event logging
	metadataSource metadata.Source // used to resolve imports
	metadata       *metadata.Package
	info           *types.Info
	fset           *token.FileSet
	pkg            *cache.Package
	pgf            *parsego.File
	start, end     token.Pos // range of interest

	// working state
	stack  []ast.Node     // path from root of the syntax tree
	tokens []semtok.Token // computed sequence of semantic tokens
}

func (tv *tokenVisitor) visit() {
	f := tv.pgf.File
	// may not be in range, but harmless
	tv.token(f.Package, len("package"), semtok.TokKeyword)
	if f.Name != nil {
		tv.token(f.Name.NamePos, len(f.Name.Name), semtok.TokNamespace)
	}
	for _, decl := range f.Decls {
		// Only look at the decls that overlap the range.
		if decl.End() <= tv.start || decl.Pos() >= tv.end {
			continue
		}
		ast.Inspect(decl, tv.inspect)
	}

	// Scan all files for imported pkgs, ignore the ambiguous pkg.
	// This is to be consistent with the behavior in [go/doc]: https://pkg.go.dev/pkg/go/doc.
	importByName := make(map[string]*types.PkgName)
	for _, pgf := range tv.pkg.CompiledGoFiles() {
		for _, imp := range pgf.File.Imports {
			if obj := tv.pkg.TypesInfo().PkgNameOf(imp); obj != nil {
				if old, ok := importByName[obj.Name()]; ok {
					if old != nil && old.Imported() != obj.Imported() {
						importByName[obj.Name()] = nil // nil => ambiguous across files
					}
					continue
				}
				importByName[obj.Name()] = obj
			}
		}
	}

	for _, cg := range f.Comments {
		for _, c := range cg.List {
			// Only look at the comment that overlap the range.
			if c.End() <= tv.start || c.Pos() >= tv.end {
				continue
			}
			tv.comment(c, importByName)
		}
	}
}

// Matches (for example) "[F]", "[*p.T]", "[p.T.M]"
// unless followed by a colon (exclude url link, e.g. "[go]: https://go.dev").
// The first group is reference name. e.g. The first group of "[*p.T.M]" is "p.T.M".
var docLinkRegex = regexp.MustCompile(`\[\*?([\pL_][\pL_0-9]*(\.[\pL_][\pL_0-9]*){0,2})](?:[^:]|$)`)

// comment emits semantic tokens for a comment.
// If the comment contains doc links or "go:" directives,
// it emits a separate token for each link or directive and
// each comment portion between them.
func (tv *tokenVisitor) comment(c *ast.Comment, importByName map[string]*types.PkgName) {
	if strings.HasPrefix(c.Text, "//go:") {
		tv.godirective(c)
		return
	}

	pkgScope := tv.pkg.Types().Scope()
	// lookupObjects interprets the name in various forms
	// (X, p.T, p.T.M, etc) and return the list of symbols
	// denoted by each identifier in the dotted list.
	lookupObjects := func(name string) (objs []types.Object) {
		scope := pkgScope
		if pkg, suffix, ok := strings.Cut(name, "."); ok {
			if obj, _ := importByName[pkg]; obj != nil {
				objs = append(objs, obj)
				scope = obj.Imported().Scope()
				name = suffix
			}
		}

		if recv, method, ok := strings.Cut(name, "."); ok {
			obj, ok := scope.Lookup(recv).(*types.TypeName)
			if !ok {
				return nil
			}
			objs = append(objs, obj)
			t, ok := obj.Type().(*types.Named)
			if !ok {
				return nil
			}
			m, _, _ := types.LookupFieldOrMethod(t, true, tv.pkg.Types(), method)
			if m == nil {
				return nil
			}
			objs = append(objs, m)
			return objs
		} else {
			obj := scope.Lookup(name)
			if obj == nil {
				return nil
			}
			if _, ok := obj.(*types.PkgName); !ok && !obj.Exported() {
				return nil
			}
			objs = append(objs, obj)
			return objs

		}
	}

	pos := c.Pos()
	for line := range strings.SplitSeq(c.Text, "\n") {
		last := 0

		for _, idx := range docLinkRegex.FindAllStringSubmatchIndex(line, -1) {
			// The first group is the reference name. e.g. "X", "p.T", "p.T.M".
			name := line[idx[2]:idx[3]]
			if objs := lookupObjects(name); len(objs) > 0 {
				if last < idx[2] {
					tv.token(pos+token.Pos(last), idx[2]-last, semtok.TokComment)
				}
				offset := pos + token.Pos(idx[2])
				for i, obj := range objs {
					if i > 0 {
						tv.token(offset, len("."), semtok.TokComment)
						offset += token.Pos(len("."))
					}
					id, rest, _ := strings.Cut(name, ".")
					name = rest
					tok, mods := tv.appendObjectModifiers(nil, obj)
					tv.token(offset, len(id), tok, mods...)
					offset += token.Pos(len(id))
				}
				last = idx[3]
			}
		}
		if last != len(c.Text) {
			tv.token(pos+token.Pos(last), len(line)-last, semtok.TokComment)
		}
		pos += token.Pos(len(line) + 1)
	}
}

// token emits a token of the specified extent and semantics.
func (tv *tokenVisitor) token(start token.Pos, length int, typ semtok.Type, modifiers ...semtok.Modifier) {
	if !start.IsValid() {
		return
	}
	if length <= 0 {
		return // vscode doesn't like 0-length Tokens
	}
	end := start + token.Pos(length)
	if start >= tv.end || end <= tv.start {
		return
	}
	// want a line and column from start (in LSP coordinates). Ignore line directives.
	rng, err := tv.pgf.PosRange(start, end)
	if err != nil {
		event.Error(tv.ctx, "failed to convert to range", err)
		return
	}
	if rng.End.Line != rng.Start.Line {
		// this happens if users are typing at the end of the file, but report nothing
		return
	}
	tv.tokens = append(tv.tokens, semtok.Token{
		Line:      rng.Start.Line,
		Start:     rng.Start.Character,
		Len:       rng.End.Character - rng.Start.Character, // (on same line)
		Type:      typ,
		Modifiers: modifiers,
	})
}

// strStack converts the stack to a string, for debugging and error messages.
func (tv *tokenVisitor) strStack() string {
	msg := []string{"["}
	for i := len(tv.stack) - 1; i >= 0; i-- {
		n := tv.stack[i]
		msg = append(msg, strings.TrimPrefix(fmt.Sprintf("%T", n), "*ast."))
	}
	if len(tv.stack) > 0 {
		pos := tv.stack[len(tv.stack)-1].Pos()
		if _, err := safetoken.Offset(tv.pgf.Tok, pos); err != nil {
			msg = append(msg, fmt.Sprintf("invalid position %v for %s", pos, tv.pgf.URI))
		} else {
			posn := safetoken.Position(tv.pgf.Tok, pos)
			msg = append(msg, fmt.Sprintf("(%s:%d,col:%d)",
				filepath.Base(posn.Filename), posn.Line, posn.Column))
		}
	}
	msg = append(msg, "]")
	return strings.Join(msg, " ")
}

// srcLine returns the source text for n (truncated at first newline).
func (tv *tokenVisitor) srcLine(n ast.Node) string {
	file := tv.pgf.Tok
	line := safetoken.Line(file, n.Pos())
	start, err := safetoken.Offset(file, file.LineStart(line))
	if err != nil {
		return ""
	}
	end := start
	for ; end < len(tv.pgf.Src) && tv.pgf.Src[end] != '\n'; end++ {

	}
	return string(tv.pgf.Src[start:end])
}

func (tv *tokenVisitor) inspect(n ast.Node) (descend bool) {
	if n == nil {
		tv.stack = tv.stack[:len(tv.stack)-1] // pop
		return true
	}
	tv.stack = append(tv.stack, n) // push
	defer func() {
		if !descend {
			tv.stack = tv.stack[:len(tv.stack)-1] // pop
		}
	}()

	switch n := n.(type) {
	case *ast.ArrayType:
	case *ast.AssignStmt:
		tv.token(n.TokPos, len(n.Tok.String()), semtok.TokOperator)
	case *ast.BasicLit:
		if n.Kind == token.STRING {
			if strings.Contains(n.Value, "\n") {
				// has to be a string.
				tv.multiline(n.Pos(), n.End(), semtok.TokString)
			} else if !tv.formatString(n) {
				// not a format string, color the whole as a TokString.
				tv.token(n.Pos(), len(n.Value), semtok.TokString)
			}
		} else {
			tv.token(n.Pos(), len(n.Value), semtok.TokNumber)
		}
	case *ast.BinaryExpr:
		tv.token(n.OpPos, len(n.Op.String()), semtok.TokOperator)
	case *ast.BlockStmt:
	case *ast.BranchStmt:
		tv.token(n.TokPos, len(n.Tok.String()), semtok.TokKeyword)
	case *ast.CallExpr:
		if n.Ellipsis.IsValid() {
			tv.token(n.Ellipsis, len("..."), semtok.TokOperator)
		}
	case *ast.CaseClause:
		iam := "case"
		if n.List == nil {
			iam = "default"
		}
		tv.token(n.Case, len(iam), semtok.TokKeyword)
	case *ast.ChanType:
		// chan | chan <- | <- chan
		switch {
		case n.Arrow == token.NoPos:
			tv.token(n.Begin, len("chan"), semtok.TokKeyword)
		case n.Arrow == n.Begin:
			tv.token(n.Arrow, 2, semtok.TokOperator)
			pos := tv.findKeyword("chan", n.Begin+2, n.Value.Pos())
			tv.token(pos, len("chan"), semtok.TokKeyword)
		case n.Arrow != n.Begin:
			tv.token(n.Begin, len("chan"), semtok.TokKeyword)
			tv.token(n.Arrow, 2, semtok.TokOperator)
		}
	case *ast.CommClause:
		length := len("case")
		if n.Comm == nil {
			length = len("default")
		}
		tv.token(n.Case, length, semtok.TokKeyword)
	case *ast.CompositeLit:
	case *ast.DeclStmt:
	case *ast.DeferStmt:
		tv.token(n.Defer, len("defer"), semtok.TokKeyword)
	case *ast.Ellipsis:
		tv.token(n.Ellipsis, len("..."), semtok.TokOperator)
	case *ast.EmptyStmt:
	case *ast.ExprStmt:
	case *ast.Field:
	case *ast.FieldList:
	case *ast.ForStmt:
		tv.token(n.For, len("for"), semtok.TokKeyword)
	case *ast.FuncDecl:
	case *ast.FuncLit:
	case *ast.FuncType:
		if n.Func != token.NoPos {
			tv.token(n.Func, len("func"), semtok.TokKeyword)
		}
	case *ast.GenDecl:
		tv.token(n.TokPos, len(n.Tok.String()), semtok.TokKeyword)
	case *ast.GoStmt:
		tv.token(n.Go, len("go"), semtok.TokKeyword)
	case *ast.Ident:
		tv.ident(n)
	case *ast.IfStmt:
		tv.token(n.If, len("if"), semtok.TokKeyword)
		if n.Else != nil {
			// x.Body.End() or x.Body.End()+1, not that it matters
			pos := tv.findKeyword("else", n.Body.End(), n.Else.Pos())
			tv.token(pos, len("else"), semtok.TokKeyword)
		}
	case *ast.ImportSpec:
		tv.importSpec(n)
		return false
	case *ast.IncDecStmt:
		tv.token(n.TokPos, len(n.Tok.String()), semtok.TokOperator)
	case *ast.IndexExpr:
	case *ast.IndexListExpr:
	case *ast.InterfaceType:
		tv.token(n.Interface, len("interface"), semtok.TokKeyword)
	case *ast.KeyValueExpr:
	case *ast.LabeledStmt:
	case *ast.MapType:
		tv.token(n.Map, len("map"), semtok.TokKeyword)
	case *ast.ParenExpr:
	case *ast.RangeStmt:
		tv.token(n.For, len("for"), semtok.TokKeyword)
		// x.TokPos == token.NoPos is legal (for range foo {})
		offset := n.TokPos
		if offset == token.NoPos {
			offset = n.For
		}
		pos := tv.findKeyword("range", offset, n.X.Pos())
		tv.token(pos, len("range"), semtok.TokKeyword)
	case *ast.ReturnStmt:
		tv.token(n.Return, len("return"), semtok.TokKeyword)
	case *ast.SelectStmt:
		tv.token(n.Select, len("select"), semtok.TokKeyword)
	case *ast.SelectorExpr:
	case *ast.SendStmt:
		tv.token(n.Arrow, len("<-"), semtok.TokOperator)
	case *ast.SliceExpr:
	case *ast.StarExpr:
		tv.token(n.Star, len("*"), semtok.TokOperator)
	case *ast.StructType:
		tv.token(n.Struct, len("struct"), semtok.TokKeyword)
	case *ast.SwitchStmt:
		tv.token(n.Switch, len("switch"), semtok.TokKeyword)
	case *ast.TypeAssertExpr:
		if n.Type == nil {
			pos := tv.findKeyword("type", n.Lparen, n.Rparen)
			tv.token(pos, len("type"), semtok.TokKeyword)
		}
	case *ast.TypeSpec:
	case *ast.TypeSwitchStmt:
		tv.token(n.Switch, len("switch"), semtok.TokKeyword)
	case *ast.UnaryExpr:
		tv.token(n.OpPos, len(n.Op.String()), semtok.TokOperator)
	case *ast.ValueSpec:
	// things only seen with parsing or type errors, so ignore them
	case *ast.BadDecl, *ast.BadExpr, *ast.BadStmt:
		return false
	// not going to see these
	case *ast.File, *ast.Package:
		tv.errorf("implement %T %s", n, safetoken.Position(tv.pgf.Tok, n.Pos()))
	// other things we knowingly ignore
	case *ast.Comment, *ast.CommentGroup:
		return false
	default:
		tv.errorf("failed to implement %T", n)
	}
	return true
}

// formatString tries to report directives and string literals
// inside a (possible) printf-like call, it returns false and does nothing
// if the string is not a format string.
func (tv *tokenVisitor) formatString(lit *ast.BasicLit) bool {
	if len(tv.stack) <= 1 {
		return false
	}
	call, ok := tv.stack[len(tv.stack)-2].(*ast.CallExpr)
	if !ok {
		return false
	}
	lastNonVariadic, idx := formatStringAndIndex(tv.info, call)
	if idx == -1 || lit != lastNonVariadic {
		return false
	}
	format, err := strconv.Unquote(lit.Value)
	if err != nil {
		return false
	}
	if !strings.Contains(format, "%") {
		return false
	}
	operations, err := fmtstr.Parse(format, idx)
	if err != nil {
		return false
	}

	// It's a format string, compute interleaved sub range of directives and literals.
	// pos tracks literal substring position within the overall BasicLit.
	pos := lit.ValuePos
	for _, op := range operations {
		// Skip "%%".
		if op.Verb.Verb == '%' {
			continue
		}
		rng, err := astutil.RangeInStringLiteral(lit, op.Range.Start, op.Range.End)
		if err != nil {
			return false
		}
		// Report literal substring.
		tv.token(pos, int(rng.Start-pos), semtok.TokString)
		// Report formatting directive.
		tv.token(rng.Start, int(rng.EndPos-rng.Start), semtok.TokString, semtok.ModFormat)
		pos = rng.EndPos
	}
	// Report remaining literal substring.
	tv.token(pos, int(lit.End()-pos), semtok.TokString)
	return true
}

func (tv *tokenVisitor) appendObjectModifiers(mods []semtok.Modifier, obj types.Object) (semtok.Type, []semtok.Modifier) {
	if obj.Pkg() == nil {
		mods = append(mods, semtok.ModDefaultLibrary)
	}

	// Note: PkgName, Builtin, Label have type Invalid, which adds no modifiers.
	mods = appendTypeModifiers(mods, obj.Type())

	switch obj := obj.(type) {
	case *types.PkgName:
		return semtok.TokNamespace, mods

	case *types.Builtin:
		return semtok.TokFunction, mods

	case *types.Func:
		if obj.Signature().Recv() != nil {
			return semtok.TokMethod, mods
		} else {
			return semtok.TokFunction, mods
		}

	case *types.TypeName:
		if is[*types.TypeParam](types.Unalias(obj.Type())) {
			return semtok.TokTypeParam, mods
		}
		return semtok.TokType, mods

	case *types.Const:
		mods = append(mods, semtok.ModReadonly)
		return semtok.TokVariable, mods

	case *types.Var:
		switch obj.Kind() {
		case types.PackageVar:
			mods = append(mods, semtok.ModStatic)
		case types.RecvVar, types.ParamVar:
			return semtok.TokParameter, mods
		case types.FieldVar:
			return semtok.TokProperty, mods
		}
		return semtok.TokVariable, mods

	case *types.Label:
		return semtok.TokLabel, mods

	case *types.Nil:
		mods = append(mods, semtok.ModReadonly)
		return semtok.TokVariable, mods
	}

	panic(obj)
}

// appendTypeModifiers appends optional modifiers that describe the top-level
// type constructor of t: "pointer", "map", etc.
func appendTypeModifiers(mods []semtok.Modifier, t types.Type) []semtok.Modifier {
	// For a type parameter, don't report "interface".
	if is[*types.TypeParam](types.Unalias(t)) {
		return mods
	}

	switch t := t.Underlying().(type) {
	case *types.Interface:
		mods = append(mods, semtok.ModInterface)
	case *types.Struct:
		mods = append(mods, semtok.ModStruct)
	case *types.Signature:
		mods = append(mods, semtok.ModSignature)
	case *types.Pointer:
		mods = append(mods, semtok.ModPointer)
	case *types.Array:
		mods = append(mods, semtok.ModArray)
	case *types.Map:
		mods = append(mods, semtok.ModMap)
	case *types.Slice:
		mods = append(mods, semtok.ModSlice)
	case *types.Chan:
		mods = append(mods, semtok.ModChan)
	case *types.Basic:
		switch t.Kind() {
		case types.Invalid:
			// ignore (e.g. Builtin, PkgName, Label)
		case types.String:
			mods = append(mods, semtok.ModString)
		case types.Bool:
			mods = append(mods, semtok.ModBool)
		case types.UnsafePointer:
			mods = append(mods, semtok.ModPointer)
		default:
			if t.Info()&types.IsNumeric != 0 {
				mods = append(mods, semtok.ModNumber)
			}
		}
	}
	return mods
}

func (tv *tokenVisitor) ident(id *ast.Ident) {
	var (
		tok  semtok.Type
		mods []semtok.Modifier
		obj  types.Object
		ok   bool
	)
	if obj, _ = tv.info.Defs[id]; obj != nil {
		// definition
		mods = append(mods, semtok.ModDefinition)
		tok, mods = tv.appendObjectModifiers(mods, obj)

	} else if obj, ok = tv.info.Uses[id]; ok {
		// use
		tok, mods = tv.appendObjectModifiers(mods, obj)

	} else if tok, mods = tv.unkIdent(id); tok != "" {
		// ok

	} else {
		return
	}

	// Emit a token for the identifier's extent.
	tv.token(id.Pos(), len(id.Name), tok, mods...)

	if semDebug {
		q := "nil"
		if obj != nil {
			q = fmt.Sprintf("%T", obj.Type()) // e.g. "*types.Map"
		}
		log.Printf(" use %s/%T/%s got %s %v (%s)",
			id.Name, obj, q, tok, mods, tv.strStack())
	}
}

// unkIdent handles identifiers with no types.Object (neither use nor
// def), use the parse stack.
// A lot of these only happen when the package doesn't compile,
// but in that case it is all best-effort from the parse tree.
func (tv *tokenVisitor) unkIdent(id *ast.Ident) (semtok.Type, []semtok.Modifier) {
	def := []semtok.Modifier{semtok.ModDefinition}
	n := len(tv.stack) - 2 // parent of Ident; stack is [File ... Ident]
	if n < 0 {
		tv.errorf("no stack") // can't happen
		return "", nil
	}
	switch parent := tv.stack[n].(type) {
	case *ast.BinaryExpr, *ast.UnaryExpr, *ast.ParenExpr, *ast.StarExpr,
		*ast.IncDecStmt, *ast.SliceExpr, *ast.ExprStmt, *ast.IndexExpr,
		*ast.ReturnStmt, *ast.ChanType, *ast.SendStmt,
		*ast.ForStmt,      // possibly incomplete
		*ast.IfStmt,       /* condition */
		*ast.KeyValueExpr, // either key or value
		*ast.IndexListExpr:
		return semtok.TokVariable, nil
	case *ast.Ellipsis:
		return semtok.TokType, nil
	case *ast.CaseClause:
		if n-2 >= 0 && is[ast.TypeSwitchStmt](tv.stack[n-2]) {
			return semtok.TokType, nil
		}
		return semtok.TokVariable, nil
	case *ast.ArrayType:
		if id == parent.Len {
			// or maybe a Type Param, but we can't just from the parse tree
			return semtok.TokVariable, nil
		} else {
			return semtok.TokType, nil
		}
	case *ast.MapType:
		return semtok.TokType, nil
	case *ast.CallExpr:
		if id == parent.Fun {
			return semtok.TokFunction, nil
		}
		return semtok.TokVariable, nil
	case *ast.SwitchStmt:
		return semtok.TokVariable, nil
	case *ast.TypeAssertExpr:
		if id == parent.X {
			return semtok.TokVariable, nil
		} else if id == parent.Type {
			return semtok.TokType, nil
		}
	case *ast.ValueSpec:
		if slices.Contains(parent.Names, id) {
			return semtok.TokVariable, def
		}
		for _, p := range parent.Values {
			if p == id {
				return semtok.TokVariable, nil
			}
		}
		return semtok.TokType, nil
	case *ast.SelectorExpr: // e.ti.Selections[nd] is nil, so no help
		if n-1 >= 0 {
			if ce, ok := tv.stack[n-1].(*ast.CallExpr); ok {
				// ... CallExpr SelectorExpr Ident (_.x())
				if ce.Fun == parent && parent.Sel == id {
					return semtok.TokFunction, nil
				}
			}
		}
		return semtok.TokVariable, nil
	case *ast.AssignStmt:
		for _, p := range parent.Lhs {
			// x := ..., or x = ...
			if p == id {
				if parent.Tok != token.DEFINE {
					def = nil
				}
				return semtok.TokVariable, def // '_' in _ = ...
			}
		}
		// RHS, = x
		return semtok.TokVariable, nil
	case *ast.TypeSpec: // it's a type if it is either the Name or the Type
		if id == parent.Type {
			def = nil
		}
		return semtok.TokType, def
	case *ast.Field:
		// ident could be type in a field, or a method in an interface type, or a variable
		if id == parent.Type {
			return semtok.TokType, nil
		}
		if n > 2 &&
			is[*ast.InterfaceType](tv.stack[n-2]) &&
			is[*ast.FieldList](tv.stack[n-1]) {

			return semtok.TokMethod, def
		}
		return semtok.TokVariable, nil
	case *ast.LabeledStmt:
		if id == parent.Label {
			return semtok.TokLabel, def
		}
	case *ast.BranchStmt:
		if id == parent.Label {
			return semtok.TokLabel, nil
		}
	case *ast.CompositeLit:
		if parent.Type == id {
			return semtok.TokType, nil
		}
		return semtok.TokVariable, nil
	case *ast.RangeStmt:
		if parent.Tok != token.DEFINE {
			def = nil
		}
		return semtok.TokVariable, def
	case *ast.FuncDecl:
		return semtok.TokFunction, def
	default:
		tv.errorf("%T unexpected: %s %s%q", parent, id.Name, tv.strStack(), tv.srcLine(id))
	}
	return "", nil
}

// multiline emits a multiline token (`string` or /*comment*/).
func (tv *tokenVisitor) multiline(start, end token.Pos, tok semtok.Type) {
	// TODO(adonovan): test with non-ASCII.

	f := tv.fset.File(start)
	// the hard part is finding the lengths of lines. include the \n
	length := func(line int) int {
		n := f.LineStart(line)
		if line >= f.LineCount() {
			return f.Size() - int(n)
		}
		return int(f.LineStart(line+1) - n)
	}
	spos := safetoken.StartPosition(tv.fset, start)
	epos := safetoken.EndPosition(tv.fset, end)
	sline := spos.Line
	eline := epos.Line
	// first line is from spos.Column to end
	tv.token(start, length(sline)-spos.Column, tok) // leng(sline)-1 - (spos.Column-1)
	for i := sline + 1; i < eline; i++ {
		// intermediate lines are from 1 to end
		tv.token(f.LineStart(i), length(i)-1, tok) // avoid the newline
	}
	// last line is from 1 to epos.Column
	tv.token(f.LineStart(eline), epos.Column-1, tok) // columns are 1-based
}

// findKeyword returns the position of a keyword by searching within
// the specified range, for when it cannot be exactly known from the AST.
// It returns NoPos if the keyword was not present in the source due to parse error.
func (tv *tokenVisitor) findKeyword(keyword string, start, end token.Pos) token.Pos {
	// TODO(adonovan): use safetoken.Offset.
	offset := int(start) - tv.pgf.Tok.Base()
	last := int(end) - tv.pgf.Tok.Base()
	buf := tv.pgf.Src
	idx := bytes.Index(buf[offset:last], []byte(keyword))
	if idx < 0 {
		// Ill-formed code may form syntax trees without their usual tokens.
		// For example, "type _ <-<-chan int" parses as <-chan (chan int),
		// with two nested ChanTypes but only one chan keyword.
		return token.NoPos
	}
	return start + token.Pos(idx)
}

func (tv *tokenVisitor) importSpec(spec *ast.ImportSpec) {
	// a local package name or the last component of the Path
	if spec.Name != nil {
		name := spec.Name.String()
		if name != "_" && name != "." {
			tv.token(spec.Name.Pos(), len(name), semtok.TokNamespace)
		}
		return // don't mark anything for . or _
	}
	importPath := metadata.UnquoteImportPath(spec)
	if importPath == "" {
		return
	}
	// Import strings are implementation defined. Try to match with parse information.
	depID := tv.metadata.DepsByImpPath[importPath]
	if depID == "" {
		return
	}
	depMD := tv.metadataSource.Metadata(depID)
	if depMD == nil {
		// unexpected, but impact is that maybe some import is not colored
		return
	}
	// Check whether the original literal contains the package's declared name.
	j := strings.LastIndex(spec.Path.Value, string(depMD.Name))
	if j < 0 {
		// Package name does not match import path, so there is nothing to report.
		return
	}
	// Report virtual declaration at the position of the substring.
	start := spec.Path.Pos() + token.Pos(j)
	tv.token(start, len(depMD.Name), semtok.TokNamespace)
}

// errorf logs an error and reports a bug.
func (tv *tokenVisitor) errorf(format string, args ...any) {
	msg := fmt.Sprintf(format, args...)
	bug.Report(msg)
	event.Error(tv.ctx, tv.strStack(), errors.New(msg))
}

var godirectives = map[string]struct{}{
	// https://pkg.go.dev/cmd/compile
	"noescape":       {},
	"uintptrescapes": {},
	"noinline":       {},
	"norace":         {},
	"nosplit":        {},
	"linkname":       {},

	// https://pkg.go.dev/go/build
	"build":               {},
	"binary-only-package": {},
	"embed":               {},
}

// Tokenize godirective at the start of the comment c, if any, and the surrounding comment.
// If there is any failure, emits the entire comment as a TokComment token.
// Directives are highlighted as-is, even if used incorrectly. Typically there are
// dedicated analyzers that will warn about misuse.
func (tv *tokenVisitor) godirective(c *ast.Comment) {
	// First check if '//go:directive args...' is a valid directive.
	directive, args, _ := strings.Cut(c.Text, " ")
	kind, _ := stringsCutPrefix(directive, "//go:")
	if _, ok := godirectives[kind]; !ok {
		// Unknown 'go:' directive.
		tv.token(c.Pos(), len(c.Text), semtok.TokComment)
		return
	}

	// Make the 'go:directive' part stand out, the rest is comments.
	tv.token(c.Pos(), len("//"), semtok.TokComment)

	directiveStart := c.Pos() + token.Pos(len("//"))
	tv.token(directiveStart, len(directive[len("//"):]), semtok.TokNamespace)

	if len(args) > 0 {
		tailStart := c.Pos() + token.Pos(len(directive)+len(" "))
		tv.token(tailStart, len(args), semtok.TokComment)
	}
}

// Go 1.20 strings.CutPrefix.
func stringsCutPrefix(s, prefix string) (after string, found bool) {
	if !strings.HasPrefix(s, prefix) {
		return s, false
	}
	return s[len(prefix):], true
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}


================================================
FILE: gopls/internal/golang/signature_help.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typesinternal"
)

// SignatureHelp returns information about the signature of the innermost
// function call enclosing the position, or nil if there is none.
func SignatureHelp(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range, context *protocol.SignatureHelpContext) (*protocol.SignatureInformation, error) {
	ctx, done := event.Start(ctx, "golang.SignatureHelp")
	defer done()

	// We need full type-checking here, as we must type-check function bodies in
	// order to provide signature help at the requested position.
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, fmt.Errorf("getting file for SignatureHelp: %w", err)
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	// Find a call expression surrounding the query position.
	var callExpr *ast.CallExpr
	path, _ := astutil.PathEnclosingInterval(pgf.File, start, end)
	if path == nil {
		return nil, fmt.Errorf("cannot find node enclosing position")
	}
	info := pkg.TypesInfo()
	var fnval ast.Expr
loop:
	for i, node := range path {
		switch node := node.(type) {
		case *ast.Ident:
			// If the selected text is a function/method Ident or SelectorExpr,
			// even one not in function call position,
			// show help for its signature. Example:
			//    once.Do(initialize⁁)
			// should show help for initialize, not once.Do.
			if t := info.TypeOf(node); t != nil &&
				info.Defs[node] == nil &&
				is[*types.Signature](t.Underlying()) {
				if sel, ok := path[i+1].(*ast.SelectorExpr); ok && sel.Sel == node {
					fnval = sel // e.g. fmt.Println⁁
				} else {
					fnval = node
				}
				break loop
			}
		case *ast.CallExpr:
			// Beware: the ')' may be missing.
			if node.Lparen <= start && end <= node.Rparen {
				callExpr = node
				fnval = callExpr.Fun
				break loop
			}
		case *ast.FuncLit, *ast.FuncType, *ast.CompositeLit:
			// The user is within an anonymous function or
			// a composite literal, which may be the argument
			// to the *ast.CallExpr.
			// Don't show signature help in this case.
			return nil, nil
		case *ast.BasicLit:
			// golang/go#43397: don't offer signature help when the user is typing
			// in a string literal unless it was manually invoked or help is already active.
			if node.Kind == token.STRING &&
				(context == nil || (context.TriggerKind != protocol.SigInvoked && !context.IsRetrigger)) {
				return nil, nil
			}
		}
	}

	if fnval == nil {
		return nil, nil
	}

	// Get the type information for the function being called.
	var sig *types.Signature
	if tv, ok := info.Types[fnval]; !ok {
		return nil, fmt.Errorf("cannot get type for Fun %[1]T (%[1]v)", fnval)
	} else if tv.IsType() {
		return nil, nil // a conversion, not a call
	} else if sig, ok = tv.Type.Underlying().(*types.Signature); !ok {
		return nil, fmt.Errorf("call operand is not a func or type: %[1]T (%[1]v)", fnval)
	}
	// Inv: sig != nil

	// Get the object representing the function, if available.
	// There is no object in certain cases such as calling a function returned by
	// a function (e.g. "foo()()").
	var obj types.Object
	switch t := fnval.(type) {
	case *ast.Ident:
		obj = info.ObjectOf(t)
	case *ast.SelectorExpr:
		obj = info.ObjectOf(t.Sel)
	}

	if obj != nil && isBuiltin(obj) {
		// Special handling for error.Error, which is the only builtin method.
		if obj.Name() == "Error" {
			return &protocol.SignatureInformation{
				Label: "Error() string",
				// TODO(skewb1k): move the docstring for error.Error to builtin.go and reuse it across all relevant LSP methods.
				Documentation:   stringToSigInfoDocumentation("Error returns the error message.", snapshot.Options()),
				Parameters:      nil,
				ActiveParameter: nil,
			}, nil
		}
		s, err := NewBuiltinSignature(ctx, snapshot, obj.Name())
		if err != nil {
			return nil, err
		}
		return signatureInformation(s, snapshot.Options(), start, end, callExpr)
	}

	mq := MetadataQualifierForFile(snapshot, pgf.File, pkg.Metadata())
	qual := typesinternal.FileQualifier(pgf.File, pkg.Types())
	var (
		comment *ast.CommentGroup
		name    string
	)

	if obj != nil {
		comment, err = HoverDocForObject(ctx, snapshot, pkg.FileSet(), obj)
		if err != nil {
			return nil, err
		}
		name = obj.Name()
	} else {
		name = "func"
	}

	s, err := NewSignature(ctx, snapshot, pkg, sig, comment, qual, mq)
	if err != nil {
		return nil, err
	}
	s.name = name
	return signatureInformation(s, snapshot.Options(), start, end, callExpr)
}

func signatureInformation(sig *signature, options *settings.Options, start, end token.Pos, call *ast.CallExpr) (*protocol.SignatureInformation, error) {
	paramInfo := make([]protocol.ParameterInformation, 0, len(sig.params))
	for _, p := range sig.params {
		paramInfo = append(paramInfo, protocol.ParameterInformation{Label: p})
	}
	return &protocol.SignatureInformation{
		Label:           sig.name + sig.Format(),
		Documentation:   stringToSigInfoDocumentation(sig.doc, options),
		Parameters:      paramInfo,
		ActiveParameter: activeParameter(sig, start, end, call),
	}, nil
}

// activeParameter returns a pointer to a variable containing
// the index of the active parameter (if known), or nil otherwise.
func activeParameter(sig *signature, start, end token.Pos, call *ast.CallExpr) *uint32 {
	if call == nil {
		return nil
	}
	numParams := uint32(len(sig.params))
	if numParams == 0 {
		return nil
	}
	// Check if the position is even in the range of the arguments.
	if !(call.Lparen < start && end <= call.Rparen) {
		return nil
	}

	var activeParam uint32
	for _, arg := range call.Args {
		if end <= arg.End() {
			break
		}
		// Don't advance the active parameter for the last parameter of a variadic function.
		if !sig.variadic || activeParam < numParams-1 {
			activeParam++
		}
	}
	return &activeParam
}

func stringToSigInfoDocumentation(s string, options *settings.Options) *protocol.Or_SignatureInformation_documentation {
	v := s
	k := protocol.PlainText
	if options.PreferredContentFormat == protocol.Markdown {
		v = DocCommentToMarkdown(s, options)
		// whether or not content is newline terminated may not matter for LSP clients,
		// but our tests expect trailing newlines to be stripped.
		v = strings.TrimSuffix(v, "\n") // TODO(pjw): change the golden files
		k = protocol.Markdown
	}
	return &protocol.Or_SignatureInformation_documentation{
		Value: protocol.MarkupContent{
			Kind:  k,
			Value: v,
		},
	}
}


================================================
FILE: gopls/internal/golang/snapshot.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/token"
	"go/types"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// NarrowestPackageForFile is a convenience function that selects the narrowest
// non-ITV package to which this file belongs, type-checks it in the requested
// mode (full or workspace), and returns it, along with the parse tree of that
// file.
//
// The "narrowest" package is the one with the fewest number of files that
// includes the given file. This solves the problem of test variants, as the
// test will have more files than the non-test package.
//
// An intermediate test variant (ITV) package has identical source to a regular
// package but resolves imports differently. gopls should never need to
// type-check them.
//
// Type-checking is expensive. Call snapshot.ParseGo if all you need is a parse
// tree, or snapshot.MetadataForFile if you only need metadata.
func NarrowestPackageForFile(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) (*cache.Package, *parsego.File, error) {
	return selectPackageForFile(ctx, snapshot, uri, func(metas []*metadata.Package) *metadata.Package { return metas[0] })
}

// WidestPackageForFile is a convenience function that selects the widest
// non-ITV package to which this file belongs, type-checks it in the requested
// mode (full or workspace), and returns it, along with the parse tree of that
// file.
//
// The "widest" package is the one with the most number of files that includes
// the given file. Which is the test variant if one exists.
//
// An intermediate test variant (ITV) package has identical source to a regular
// package but resolves imports differently. gopls should never need to
// type-check them.
//
// Type-checking is expensive. Call snapshot.ParseGo if all you need is a parse
// tree, or snapshot.MetadataForFile if you only need metadata.
func WidestPackageForFile(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) (*cache.Package, *parsego.File, error) {
	return selectPackageForFile(ctx, snapshot, uri, func(metas []*metadata.Package) *metadata.Package { return metas[len(metas)-1] })
}

// NarrowestDeclaringPackage facilitates cross-package analysis by "jumping"
// from the current package context to the package that declares the given object.
//
// This is essential when the object of interest is defined in a different
// package than the one currently being type-checked.
//
// This function performs the context switch: it locates the file declaring
// the object, loads its narrowest package (see [NarrowestPackageForFile]),
// and returns the type-checked result.
//
// It returns the new package, the file, and the object's position translated
// to be valid within the new package's file set.
func NarrowestDeclaringPackage(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, obj types.Object) (*cache.Package, *parsego.File, token.Pos, error) {
	posn := safetoken.StartPosition(pkg.FileSet(), obj.Pos())
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, protocol.URIFromPath(posn.Filename))
	if err != nil {
		return nil, nil, token.NoPos, err
	}
	return pkg, pgf, pgf.Tok.Pos(posn.Offset), nil
}

func selectPackageForFile(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, selector func([]*metadata.Package) *metadata.Package) (*cache.Package, *parsego.File, error) {
	mps, err := snapshot.MetadataForFile(ctx, uri, true)
	if err != nil {
		return nil, nil, err
	}
	if len(mps) == 0 {
		return nil, nil, fmt.Errorf("no package metadata for file %s", uri)
	}
	mp := selector(mps)
	pkgs, err := snapshot.TypeCheck(ctx, mp.ID)
	if err != nil {
		return nil, nil, err
	}
	pkg := pkgs[0]
	pgf, err := pkg.File(uri)
	if err != nil {
		return nil, nil, err // "can't happen"
	}
	return pkg, pgf, err
}

type (
	PackageID   = metadata.PackageID
	PackagePath = metadata.PackagePath
	PackageName = metadata.PackageName
	ImportPath  = metadata.ImportPath
)

type unit = struct{}


================================================
FILE: gopls/internal/golang/splitpkg/graph.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package splitpkg

// SCC algorithm stolen from cmd/digraph.

type (
	graph    = map[int]map[int]bool
	nodeList = []int
	nodeSet  = map[int]bool
)

// addNode ensures a node exists in the graph with an initialized edge set.
func addNode(g graph, node int) map[int]bool {
	edges := g[node]
	if edges == nil {
		edges = make(map[int]bool)
		g[node] = edges
	}
	return edges
}

// addEdges adds one or more edges from a 'from' node.
func addEdges(g graph, from int, to ...int) {
	edges := addNode(g, from)
	for _, toNode := range to {
		addNode(g, toNode)
		edges[toNode] = true
	}
}

// transpose creates the transpose (reverse) of the graph.
func transpose(g graph) graph {
	rev := make(graph)
	for node, edges := range g {
		addNode(rev, node) // Ensure all nodes exist in the transposed graph
		for succ := range edges {
			addEdges(rev, succ, node)
		}
	}
	return rev
}

// sccs returns the non-trivial strongly connected components of the graph.
func sccs(g graph) []nodeSet {
	// Kosaraju's algorithm---Tarjan is overkill here.
	//
	// TODO(adonovan): factor with Tarjan's algorithms from
	// go/ssa/dom.go,
	// go/callgraph/vta/propagation.go,
	// ../../cache/typerefs/refs.go,
	// ../../cache/metadata/graph.go.

	// Forward pass.
	S := make(nodeList, 0, len(g)) // postorder stack
	seen := make(nodeSet)
	var visit func(node int)
	visit = func(node int) {
		if !seen[node] {
			seen[node] = true
			for e := range g[node] {
				visit(e)
			}
			S = append(S, node)
		}
	}
	for node := range g {
		visit(node)
	}

	// Reverse pass.
	rev := transpose(g)
	var scc nodeSet
	seen = make(nodeSet)
	var rvisit func(node int)
	rvisit = func(node int) {
		if !seen[node] {
			seen[node] = true
			scc[node] = true
			for e := range rev[node] {
				rvisit(e)
			}
		}
	}
	var sccs []nodeSet
	for len(S) > 0 {
		top := S[len(S)-1]
		S = S[:len(S)-1] // pop
		if !seen[top] {
			scc = make(nodeSet)
			rvisit(top)
			if len(scc) == 1 && !g[top][top] {
				continue
			}
			sccs = append(sccs, scc)
		}
	}
	return sccs
}


================================================
FILE: gopls/internal/golang/splitpkg/splitpkg.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package splitpkg

// This file produces the "Split package" HTML report.
//
// The server persistently holds, for each PackageID, the current set
// of components and the mapping from declared names to components. On
// each page reload or JS reload() call, the server type-checks the
// package, computes its symbol reference graph, projects it onto
// components, then returns the component reference graph, and if it
// is cyclic, which edges form cycles. Thus changes to the package
// source are reflected in the client UI at the next page reload or JS
// reload() event.
//
// See also:
// - ../codeaction.go - offers the CodeAction command
// - ../../server/command.go - handles the command by opening a web page
// - ../../server/server.go - handles the HTTP request and calls this function
// - ../../server/assets/splitpkg.js - client-side logic
// - ../../test/integration/web/splitpkg_test.go - integration test of server
//
// TODO(adonovan): future work
//
// Refine symbol reference graph:
// - deal with enums (values must stay together; implicit dependency on iota expression)
// - deal with coupled vars "var x, y = f()"
// - deal with declared methods (coupled to receiver named type)
// - deal with fields/interface methods (loosely coupled to struct/interface type)
//   In both cases the field/method name must be either exported or in the same component.
//
// UI:
// - make shift click extend selection of a range of checkboxes.
// - display two-level grouping of decls and specs: var ( x int; y int )
// - indicate when package has type errors (data may be incomplete).
//
// Code transformation:
// - add "Split" button that is green when acyclic. It should:
//   1) move each component into a new package, or separate file of
//      the same package. (The UI will need to hold this user
//      intent in the list of components.)
//   2) ensure that each declaration referenced from another package
//      is public, renaming as needed.
//   3) update package decls, imports, package docs, file docs,
//      doc comments, etc.
// Should we call this feature "Reorganize package" or "Decompose package"
// until the "Split" button actually exists?

import (
	"bytes"
	"crypto/sha256"
	_ "embed"
	"encoding/json"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"html/template"
	"log"
	"strconv"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/typesinternal"
)

//go:embed splitpkg.html.tmpl
var htmlTmpl string

// HTML returns the HTML for the main "Split package" page, for the
// /splitpkg endpoint. The real magic happens in JavaScript; see
// ../../server/assets/splitpkg.js.
func HTML(pkgpath metadata.PackagePath) []byte {
	t, err := template.New("splitpkg.html").Parse(htmlTmpl)
	if err != nil {
		log.Fatal(err)
	}
	data := struct {
		Title string
	}{
		Title: fmt.Sprintf("Split package %s", pkgpath),
	}
	var buf bytes.Buffer
	if err := t.Execute(&buf, data); err != nil {
		log.Fatal(err)
	}
	return buf.Bytes()
}

const cacheKind = "splitpkg" // filecache kind

func cacheKey(pkgID metadata.PackageID) [32]byte {
	return sha256.Sum256([]byte(pkgID))
}

// UpdateComponentsJSON parses the JSON description of components and
// their assigned declarations and updates the component state for the
// specified package.
func UpdateComponentsJSON(pkgID metadata.PackageID, data []byte) error {
	return filecache.Set(cacheKind, cacheKey(pkgID), data)
}

// Web is an abstraction of gopls' web server.
type Web interface {
	// SrcURL forms URLs that cause the editor to open a file at a specific position.
	SrcURL(filename string, line, col8 int) protocol.URI
}

// JSON returns the JSON encoding of the data needed by
// the /splitpkg-json endpoint for the specified package. It includes:
//   - the set of names declared by the package, grouped by file;
//   - the set of components and their assigned declarations from
//     the most recent call to [UpdateComponentsJSON]; and
//   - the component graph derived from them, along with the
//     sets of reference that give rise to each edge.
func JSON(pkg *cache.Package, web Web) ([]byte, error) {
	// Retrieve package's most recent state from the file cache.
	var comp ComponentsJSON
	data, err := filecache.Get(cacheKind, cacheKey(pkg.Metadata().ID))
	if err != nil {
		if err != filecache.ErrNotFound {
			return nil, err
		}
		// cache miss: use zero value
	} else if err := json.Unmarshal(data, &comp); err != nil {
		return nil, err
	}

	// Prepare to construct symbol reference graph.
	var (
		info    = pkg.TypesInfo()
		symbols = make(map[types.Object]*symbol)
	)

	// setName records the UI name for an object.
	// (The UI name disambiguates "init", "_", etc.)
	setName := func(obj types.Object, name string) {
		symbols[obj] = &symbol{
			name:      name,
			component: comp.Assignments[name], // missing => "default"
		}
	}

	// Pass 1: name everything, since naming is order-dependent.
	var initCounter, blankCounter int
	for _, pgf := range pkg.CompiledGoFiles() {
		for _, decl := range pgf.File.Decls {
			switch decl := decl.(type) {
			case *ast.FuncDecl:
				if fn, ok := info.Defs[decl.Name].(*types.Func); ok {
					// For now we treat methods as first class decls,
					// but since they are coupled to the named type
					// they should be omitted in the UI for brevity.
					name := fn.Name()
					if recv := fn.Signature().Recv(); recv != nil {
						fn = fn.Origin()
						_, named := typesinternal.ReceiverNamed(recv)
						name = named.Obj().Name() + "." + name
					} else if name == "init" {
						// Disambiguate top-level init functions.
						name += suffix(&initCounter)
					}
					if name == "_" { // (function or method)
						name += suffix(&blankCounter)
					}
					setName(fn, name)
				}

			case *ast.GenDecl:
				switch decl.Tok {
				case token.CONST, token.VAR:
					for _, spec := range decl.Specs {
						spec := spec.(*ast.ValueSpec)
						for _, id := range spec.Names {
							if obj := info.Defs[id]; obj != nil {
								name := obj.Name()
								if name == "_" {
									name += suffix(&blankCounter)
								}
								setName(obj, name)
							}
						}
					}

				case token.TYPE:
					for _, spec := range decl.Specs {
						spec := spec.(*ast.TypeSpec)
						if obj := info.Defs[spec.Name]; obj != nil {
							name := obj.Name()
							if name == "_" {
								name += suffix(&blankCounter)
							}
							setName(obj, name)
						}
					}
				}
			}
		}
	}

	// Pass 2: compute symbol reference graph, project onto
	// component dependency graph, and build JSON response.
	var (
		files []*fileJSON
		refs  []*refJSON
	)
	for _, pgf := range pkg.CompiledGoFiles() {
		identURL := func(id *ast.Ident) string {
			posn := safetoken.Position(pgf.Tok, id.Pos())
			return web.SrcURL(posn.Filename, posn.Line, posn.Column)
		}
		newCollector := func(from *symbol) *refCollector {
			return &refCollector{
				from:     from,
				identURL: identURL,
				pkg:      pkg.Types(),
				info:     info,
				symbols:  symbols,
			}
		}
		var decls []*declJSON
		for _, decl := range pgf.File.Decls {
			var (
				kind  string
				specs []*specJSON
			)
			switch decl := decl.(type) {
			case *ast.FuncDecl:
				kind = "func"
				if fn, ok := info.Defs[decl.Name].(*types.Func); ok {
					symbol := symbols[fn]
					rc := newCollector(symbol).collect(decl)
					refs = append(refs, rc.refs...)
					specs = append(specs, &specJSON{
						Name: symbol.name,
						URL:  identURL(decl.Name),
					})
				}

			case *ast.GenDecl:
				kind = decl.Tok.String()

				switch decl.Tok {
				case token.CONST, token.VAR:
					for _, spec := range decl.Specs {
						spec := spec.(*ast.ValueSpec)
						for i, id := range spec.Names {
							if obj := info.Defs[id]; obj != nil {
								symbol := symbols[obj]
								rc := newCollector(symbol)
								// If there's a type,
								// all RHSs depend on it.
								if spec.Type != nil {
									rc.collect(spec.Type)
								}
								switch len(spec.Values) {
								case len(spec.Names):
									// var x, y = a, b
									rc.collect(spec.Values[i])
								case 1:
									// var x, y = f()
									rc.collect(spec.Values[0])
								case 0:
									// var x T
								}
								refs = append(refs, rc.refs...)
								specs = append(specs, &specJSON{
									Name: symbol.name,
									URL:  identURL(id),
								})
							}
						}
					}

				case token.TYPE:
					for _, spec := range decl.Specs {
						spec := spec.(*ast.TypeSpec)
						if obj := info.Defs[spec.Name]; obj != nil {
							symbol := symbols[obj]
							rc := newCollector(symbol).collect(spec.Type)
							refs = append(refs, rc.refs...)
							specs = append(specs, &specJSON{
								Name: symbol.name,
								URL:  identURL(spec.Name),
							})
						}
					}
				}
			}
			if len(specs) > 0 {
				decls = append(decls, &declJSON{Kind: kind, Specs: specs})
			}
		}
		files = append(files, &fileJSON{
			Base:  pgf.URI.Base(),
			URL:   web.SrcURL(pgf.URI.Path(), 1, 1),
			Decls: decls,
		})
	}

	// Compute the graph of dependencies between components, by
	// projecting the symbol dependency graph through component
	// assignments.
	var (
		g        = make(graph)
		edgeRefs = make(map[[2]int][]*refJSON) // refs that induce each intercomponent edge
	)
	for _, ref := range refs {
		from, to := ref.from, ref.to
		if from.component != to.component {
			// inter-component reference
			m, ok := g[from.component]
			if !ok {
				m = make(map[int]bool)
				g[from.component] = m
			}
			m[to.component] = true

			key := [2]int{from.component, to.component}
			edgeRefs[key] = append(edgeRefs[key], ref)
		}
	}

	// Detect cycles in the component graph
	// and record cyclic (⚠) components.
	cycles := [][]int{}        // non-nil for JSON
	scmap := make(map[int]int) // maps component index to 1 + SCC index (0 => acyclic)
	for i, scc := range sccs(g) {
		for c := range scc {
			scmap[c] = i + 1
		}
		cycles = append(cycles, moremaps.KeySlice(scc))
	}

	// Record intercomponent edges and their references.
	edges := []*edgeJSON{} // non-nil for JSON
	for edge, refs := range edgeRefs {
		from, to := edge[0], edge[1]
		edges = append(edges, &edgeJSON{
			From:   from,
			To:     to,
			Refs:   refs,
			Cyclic: scmap[from] > 0 && scmap[from] == scmap[to],
		})
	}

	return json.Marshal(ResultJSON{
		Files:      files,
		Components: comp,
		Edges:      edges,
		Cycles:     cycles,
	})
}

// A refCollector gathers intra-package references to top-level
// symbols from within one syntax tree, in lexical order.
type refCollector struct {
	from     *symbol
	identURL func(*ast.Ident) string
	pkg      *types.Package
	info     *types.Info
	index    map[types.Object]*refJSON
	symbols  map[types.Object]*symbol

	refs []*refJSON // output
}

// A symbol describes a declared name and its assigned component.
type symbol struct {
	name      string // unique name in the UI and JSON/HTTP protocol
	component int    // index of assigned component
}

// collect adds the free references of n to the collection.
func (rc *refCollector) collect(n ast.Node) *refCollector {
	var f func(n ast.Node) bool
	f = func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.SelectorExpr:
			if sel, ok := rc.info.Selections[n]; ok {
				rc.addRef(n.Sel, sel.Obj())
				ast.Inspect(n.X, f)
				return false // don't visit n.Sel
			}

		case *ast.Ident:
			if obj := rc.info.Uses[n]; obj != nil {
				rc.addRef(n, obj)
			}
		}
		return true
	}
	ast.Inspect(n, f)

	return rc
}

// addRef records a reference from id to obj.
func (rc *refCollector) addRef(id *ast.Ident, obj types.Object) {
	if obj.Pkg() != rc.pkg {
		return // cross-package reference
	}

	// Un-instantiate methods.
	if fn, ok := obj.(*types.Func); ok && fn.Signature().Recv() != nil {
		obj = fn.Origin() // G[int].method -> G[T].method
	}

	// We only care about refs to package-level symbols.
	// And methods, for now.
	decl := rc.symbols[obj]
	if decl == nil {
		return // not a package-level symbol or top-level method
	}

	if ref, ok := rc.index[obj]; !ok {
		ref = &refJSON{
			From: rc.from.name,
			To:   decl.name,
			URL:  rc.identURL(id),
			from: rc.from,
			to:   decl,
		}
		if rc.index == nil {
			rc.index = make(map[types.Object]*refJSON)
		}
		rc.index[obj] = ref
		rc.refs = append(rc.refs, ref)
	}
}

// suffix returns a subscripted decimal suffix,
// preincrementing the specified counter.
func suffix(counter *int) string {
	*counter++
	n := *counter
	return subscripter.Replace(strconv.Itoa(n))
}

var subscripter = strings.NewReplacer(
	"0", "₀",
	"1", "₁",
	"2", "₂",
	"3", "₃",
	"4", "₄",
	"5", "₅",
	"6", "₆",
	"7", "₇",
	"8", "₈",
	"9", "₉",
)

// -- JSON types --

// ResultJSON describes the result of a /splitpkg-json query.
// It is public for testing.
type ResultJSON struct {
	Components ComponentsJSON // component names and their assigned declarations
	Files      []*fileJSON    // files of the packages and their declarations and references
	Edges      []*edgeJSON    // inter-component edges and their references
	Cycles     [][]int        // sets of strongly-connected components
}

// request body of a /splitpkg-components update;
// also part of /splitpkg-json response.
type ComponentsJSON struct {
	Names       []string       `json:",omitempty"` // if empty, implied Names[0]=="default".
	Assignments map[string]int `json:",omitempty"` // maps specJSON.Name to component index; missing => 0
}

// edgeJSON describes an inter-component dependency.
type edgeJSON struct {
	From, To int        // component IDs
	Refs     []*refJSON // references that give rise to this edge
	Cyclic   bool       // edge is part of nontrivial strongly connected component
}

// fileJSON records groups decl/spec information about a single file.
type fileJSON struct {
	Base  string      // file base name
	URL   string      // showDocument link for file
	Decls []*declJSON `json:",omitempty"`
}

// declJSON groups specs (e.g. "var ( x int; y int )").
type declJSON struct {
	Kind  string      // const, var, type, func
	Specs []*specJSON `json:",omitempty"`
}

// specJSON describes a single declared name.
// (A coupled declaration "var x, y = f()" results in two specJSONs.)
type specJSON struct {
	Name string // x or T.x
	URL  string // showDocument link for declaring identifier
}

// refJSON records the first reference from a given declaration to a symbol.
// (Repeat uses of the same identifier are omitted.)
type refJSON struct {
	From, To string // x or T.x of referenced spec
	URL      string // showDocument link for referring identifier

	from, to *symbol // transient
}


================================================
FILE: gopls/internal/golang/splitpkg/splitpkg.html.tmpl
================================================
<!DOCTYPE html>
<html>
<head>
  <meta charset="UTF-8">
  <title>{{.Title}}</title>
  <link rel="stylesheet" href="/assets/common.css">
  <link rel="stylesheet" href="/assets/splitpkg.css">
  <script src="/assets/common.js"></script>
  <script src="/assets/splitpkg.js"></script>
</head>
<body>
<h1>{{.Title}}</h1>

<p class='help'>
ⓘ Use this tool to decompose a package into a set of components
whose dependencies are acyclic.

First, name a set of <a href='#components'>components</a>.

Second, assign each <a href='#assign'>declaration</a> to an
appropriate component: check their checkboxes, choose a component, and
click Apply. Use the checkbox for a file to select all declarations in
that file.

Third, examine the set of <a href='#deps'>dependencies</a> between
components. Each inter-component dependency lists the symbol
references that cross the boundary. Click on one to navigate your
editor there.

If two or more components form a dependency cycle (⚠),
you will need to either change your code,
or change the component assignments.

Iterate this process.
Reload the page to refresh after each code change.
</p>
<p class='help'>
Once you are happy with the result, you can split the package,
renaming declarations as needed to export them.
In a future release, the code transformation will be automated.
</p>

<h2>Components</h2>
<div id="components"><!--programmatic--></div>

<p>
<input size="20" id="new-component" type='text'/>
<button id="add-component">Add component</button>
[<a href='#deps'>▼ see dependencies</a>]
</p>

<hr>

<h2>Declarations</h2>

<div id="assign">
  <label for="assign-select">Assign selected declarations to component:</label>
  <select id="assign-select"><!--programmatic--></select>
  <button id="assign-apply">Apply</button>
</div>

<div id="files"><!--programmatic--></div>

<hr>

<h2>Component dependencies</h2>

<div id="deps"><!--programmatic--></div>
`


================================================
FILE: gopls/internal/golang/stub.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"fmt"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	pathpkg "path"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/golang/stubmethods"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/diff"
)

// stubMissingInterfaceMethodsFixer returns a suggested fix to declare the missing
// methods of the concrete type that is assigned to an interface type
// at the cursor position.
func stubMissingInterfaceMethodsFixer(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	si := stubmethods.GetIfaceStubInfo(pkg.FileSet(), pkg.TypesInfo(), pgf, start, end)
	if si == nil {
		return nil, nil, fmt.Errorf("nil interface request")
	}
	return insertDeclsAfter(ctx, snapshot, pkg.Metadata(), si.Fset, si.Concrete.Obj(), si.Emit)
}

// stubMissingCalledFunctionFixer returns a suggested fix to declare the missing
// method that the user may want to generate based on CallExpr
// at the cursor position.
func stubMissingCalledFunctionFixer(ctx context.Context, snapshot *cache.Snapshot, pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	si := stubmethods.GetCallStubInfo(pkg.FileSet(), pkg.TypesInfo(), pgf, start, end)
	if si == nil {
		return nil, nil, fmt.Errorf("invalid type request")
	}
	return insertDeclsAfter(ctx, snapshot, pkg.Metadata(), si.Fset, si.After, si.Emit)
}

// An emitter writes new top-level declarations into an existing
// file. References to symbols should be qualified using qual, which
// respects the local import environment.
type emitter = func(out *bytes.Buffer, qual types.Qualifier) error

// insertDeclsAfter locates the file that declares symbol sym,
// (which must be among the dependencies of mp),
// calls the emit function to generate new declarations,
// respecting the local import environment,
// and splices those declarations into the file after the declaration of sym,
// updating imports as needed.
//
// fset must provide the position of sym.
func insertDeclsAfter(ctx context.Context, snapshot *cache.Snapshot, mp *metadata.Package, fset *token.FileSet, sym types.Object, emit emitter) (*token.FileSet, *analysis.SuggestedFix, error) {
	// Parse the file declaring the sym.
	//
	// Beware: declPGF is not necessarily covered by pkg.FileSet() or si.Fset.
	declPGF, _, err := parseFull(ctx, snapshot, fset, sym)
	if err != nil {
		return nil, nil, fmt.Errorf("failed to parse file %q declaring implementation symbol: %w", declPGF.URI, err)
	}
	if declPGF.Fixed() {
		return nil, nil, fmt.Errorf("file contains parse errors: %s", declPGF.URI)
	}

	// Find metadata for the symbol's declaring package
	// as we'll need its import mapping.
	declMeta := findFileInDeps(snapshot, mp, declPGF.URI)
	if declMeta == nil {
		return nil, nil, bug.Errorf("can't find metadata for file %s among dependencies of %s", declPGF.URI, mp)
	}

	// Build import environment for the declaring file.
	// (typesinternal.FileQualifier works only for complete
	// import mappings, and requires types.)
	importEnv := make(map[ImportPath]string) // value is local name
	for _, imp := range declPGF.File.Imports {
		importPath := metadata.UnquoteImportPath(imp)
		var name string
		if imp.Name != nil {
			name = imp.Name.Name
			if name == "_" {
				continue
			} else if name == "." {
				name = "" // see types.Qualifier
			}
		} else {
			// Use the correct name from the metadata of the imported
			// package---not a guess based on the import path.
			mp := snapshot.Metadata(declMeta.DepsByImpPath[importPath])
			if mp == nil {
				continue // can't happen?
			}
			name = string(mp.Name)
		}
		importEnv[importPath] = name // latest alias wins
	}

	// Create a package name qualifier that uses the
	// locally appropriate imported package name.
	// It records any needed new imports.
	// TODO(adonovan): factor with golang.FormatVarType?
	//
	// Prior to CL 469155 this logic preserved any renaming
	// imports from the file that declares the interface
	// method--ostensibly the preferred name for imports of
	// frequently renamed packages such as protobufs.
	// Now we use the package's declared name. If this turns out
	// to be a mistake, then use parseHeader(si.iface.Pos()).
	//
	type newImport struct{ name, importPath string }
	var newImports []newImport // for AddNamedImport
	qual := func(pkg *types.Package) string {
		// TODO(adonovan): don't ignore vendor prefix.
		//
		// Ignore the current package import.
		if pkg.Path() == sym.Pkg().Path() {
			return ""
		}

		importPath := ImportPath(pkg.Path())
		name, ok := importEnv[importPath]
		if !ok {
			// Insert new import using package's declared name.
			//
			// TODO(adonovan): resolve conflict between declared
			// name and existing file-level (declPGF.File.Imports)
			// or package-level (sym.Pkg.Scope) decls by
			// generating a fresh name.
			name = pkg.Name()
			importEnv[importPath] = name
			new := newImport{importPath: string(importPath)}
			// For clarity, use a renaming import whenever the
			// local name does not match the path's last segment.
			if name != pathpkg.Base(trimVersionSuffix(new.importPath)) {
				new.name = name
			}
			newImports = append(newImports, new)
		}
		return name
	}

	// Compute insertion point for new declarations:
	// after the top-level declaration enclosing the (package-level) type.
	insertOffset, err := safetoken.Offset(declPGF.Tok, declPGF.File.End())
	if err != nil {
		return nil, nil, bug.Errorf("internal error: end position outside file bounds: %v", err)
	}
	symOffset, err := safetoken.Offset(fset.File(sym.Pos()), sym.Pos())
	if err != nil {
		return nil, nil, bug.Errorf("internal error: finding type decl offset: %v", err)
	}
	for _, decl := range declPGF.File.Decls {
		declEndOffset, err := safetoken.Offset(declPGF.Tok, decl.End())
		if err != nil {
			return nil, nil, bug.Errorf("internal error: finding decl offset: %v", err)
		}
		if declEndOffset > symOffset {
			insertOffset = declEndOffset
			break
		}
	}

	// Splice the new declarations into the file content.
	var buf bytes.Buffer
	input := declPGF.Mapper.Content // unfixed content of file
	buf.Write(input[:insertOffset])
	buf.WriteByte('\n')
	err = emit(&buf, qual)
	if err != nil {
		return nil, nil, err
	}
	buf.Write(input[insertOffset:])

	// Re-parse the file.
	fset = token.NewFileSet()
	newF, err := parser.ParseFile(fset, declPGF.URI.Path(), buf.Bytes(), parser.ParseComments|parser.SkipObjectResolution)
	if err != nil {
		return nil, nil, fmt.Errorf("could not reparse file: %w", err)
	}

	// Splice the new imports into the syntax tree.
	for _, imp := range newImports {
		astutil.AddNamedImport(fset, newF, imp.name, imp.importPath)
	}

	// Pretty-print.
	var output bytes.Buffer
	if err := format.Node(&output, fset, newF); err != nil {
		return nil, nil, fmt.Errorf("format.Node: %w", err)
	}

	// Report the diff.
	diffs := diff.Bytes(input, output.Bytes())
	return tokeninternal.FileSetFor(declPGF.Tok), // edits use declPGF.Tok
		&analysis.SuggestedFix{TextEdits: diffToTextEdits(declPGF.Tok, diffs)},
		nil
}

// diffToTextEdits converts diff (offset-based) edits to analysis (token.Pos) form.
func diffToTextEdits(tok *token.File, diffs []diff.Edit) []analysis.TextEdit {
	edits := make([]analysis.TextEdit, 0, len(diffs))
	for _, edit := range diffs {
		edits = append(edits, analysis.TextEdit{
			Pos:     tok.Pos(edit.Start),
			End:     tok.Pos(edit.End),
			NewText: []byte(edit.New),
		})
	}
	return edits
}

// trimVersionSuffix removes a trailing "/v2" (etc) suffix from a module path.
//
// This is only a heuristic as to the package's declared name, and
// should only be used for stylistic decisions, such as whether it
// would be clearer to use an explicit local name in the import
// because the declared name differs from the result of this function.
// When the name matters for correctness, look up the imported
// package's Metadata.Name.
func trimVersionSuffix(path string) string {
	dir, base := pathpkg.Split(path)
	if len(base) > 1 && base[0] == 'v' && strings.Trim(base[1:], "0123456789") == "" {
		return dir // sans "/v2"
	}
	return path
}


================================================
FILE: gopls/internal/golang/stubmethods/stubcalledfunc.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stubmethods

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"
	"unicode"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/typesutil"
	"golang.org/x/tools/internal/typesinternal"
)

var anyType = types.Universe.Lookup("any").Type()

// CallStubInfo represents a missing method
// that a receiver type is about to generate
// which has "type X has no field or method Y" error
type CallStubInfo struct {
	Fset       *token.FileSet             // the FileSet used to type-check the types below
	Receiver   typesinternal.NamedOrAlias // the method's receiver type
	MethodName string
	After      types.Object // decl after which to insert the new decl
	pointer    bool
	info       *types.Info
	curCall    inspector.Cursor // cursor to the CallExpr
}

// GetCallStubInfo extracts necessary information to generate a method definition from
// a CallExpr.
func GetCallStubInfo(fset *token.FileSet, info *types.Info, pgf *parsego.File, start, end token.Pos) *CallStubInfo {
	callCur, _ := pgf.Cursor().FindByPos(start, end)
	call, callCur := cursorutil.FirstEnclosing[*ast.CallExpr](callCur)
	if call == nil {
		return nil
	}
	s, ok := call.Fun.(*ast.SelectorExpr)
	// TODO: support generating stub functions in the same way.
	if !ok {
		return nil
	}

	// If recvExpr is a package name, compiler error would be
	// e.g., "undefined: http.bar", thus will not hit this code path.
	recvExpr := s.X
	recvType, pointer := concreteType(recvExpr, info)

	if recvType == nil || recvType.Obj().Pkg() == nil {
		return nil
	}

	// A method of a function-local type cannot be stubbed
	// since there's nowhere to put the methods.
	recv := recvType.Obj()
	if recv.Parent() != recv.Pkg().Scope() {
		return nil
	}

	after := types.Object(recv)
	// If the enclosing function declaration is a method declaration,
	// and matches the receiver type of the diagnostic,
	// insert after the enclosing method.
	decl, _ := cursorutil.FirstEnclosing[*ast.FuncDecl](callCur)
	if decl != nil && decl.Recv != nil {
		if len(decl.Recv.List) != 1 {
			return nil
		}
		mrt := info.TypeOf(decl.Recv.List[0].Type)
		if mrt != nil && types.Identical(types.Unalias(typesinternal.Unpointer(mrt)), recv.Type()) {
			after = info.ObjectOf(decl.Name)
		}
	}
	return &CallStubInfo{
		Fset:       fset,
		Receiver:   recvType,
		MethodName: s.Sel.Name,
		After:      after,
		pointer:    pointer,
		curCall:    callCur,
		info:       info,
	}
}

// Emit writes to out the missing method based on type info of si.Receiver and CallExpr.
func (si *CallStubInfo) Emit(out *bytes.Buffer, qual types.Qualifier) error {
	params := si.collectParams()
	rets := typesutil.TypesFromContext(si.info, si.curCall)
	recv := si.Receiver.Obj()
	// Pointer receiver?
	var star string
	if si.pointer {
		star = "*"
	}

	// Choose receiver name.
	// If any method has a named receiver, choose the first one.
	// Otherwise, use lowercase for the first letter of the object.
	recvName := strings.ToLower(fmt.Sprintf("%.1s", recv.Name()))
	if named, ok := types.Unalias(si.Receiver).(*types.Named); ok {
		for method := range named.Methods() {
			if recv := method.Signature().Recv(); recv.Name() != "" {
				recvName = recv.Name()
				break
			}
		}
	}

	// Emit method declaration.
	fmt.Fprintf(out, "\nfunc (%s %s%s%s) %s",
		recvName,
		star,
		recv.Name(),
		typesutil.FormatTypeParams(si.Receiver.TypeParams()),
		si.MethodName)

	// Emit parameters, avoiding name conflicts.
	seen := map[string]bool{recvName: true}
	out.WriteString("(")
	for i, param := range params {
		name := param.name
		if seen[name] {
			name = fmt.Sprintf("param%d", i+1)
		}
		seen[name] = true

		if i > 0 {
			out.WriteString(", ")
		}
		fmt.Fprintf(out, "%s %s", name, types.TypeString(param.typ, qual))
	}
	out.WriteString(") ")

	// Emit result types.
	if len(rets) > 1 {
		out.WriteString("(")
	}
	for i, r := range rets {
		if i > 0 {
			out.WriteString(", ")
		}
		out.WriteString(types.TypeString(r, qual))
	}
	if len(rets) > 1 {
		out.WriteString(")")
	}

	// Emit body.
	out.WriteString(` {
		panic("unimplemented")
}`)
	return nil
}

type param struct {
	name string
	typ  types.Type // the type of param, inferred from CallExpr
}

// collectParams gathers the parameter information needed to generate a method stub.
// The param's type default to any if there is a type error in the argument.
func (si *CallStubInfo) collectParams() []param {
	var params []param
	appendParam := func(e ast.Expr, t types.Type) {
		p := param{"param", anyType}
		if t != nil && !containsInvalid(t) {
			t = types.Default(t)
			p = param{paramName(e, t), t}
		}
		params = append(params, p)
	}

	args := si.curCall.Node().(*ast.CallExpr).Args
	for _, arg := range args {
		t := si.info.TypeOf(arg)
		switch t := t.(type) {
		// This is the case where another function call returning multiple
		// results is used as an argument.
		case *types.Tuple:
			for v := range t.Variables() {
				appendParam(arg, v.Type())
			}
		default:
			appendParam(arg, t)
		}
	}
	return params
}

// containsInvalid checks if the type name contains "invalid type",
// which is not a valid syntax to generate.
func containsInvalid(t types.Type) bool {
	typeString := types.TypeString(t, nil)
	return strings.Contains(typeString, types.Typ[types.Invalid].String())
}

// paramName heuristically chooses a parameter name from
// its argument expression and type. Caller should ensure
// typ is non-nil.
func paramName(e ast.Expr, typ types.Type) string {
	if typ == types.Universe.Lookup("error").Type() {
		return "err"
	}
	switch t := e.(type) {
	// Use the identifier's name as the argument name.
	case *ast.Ident:
		return t.Name
	// Use the Sel.Name's last section as the argument name.
	case *ast.SelectorExpr:
		return lastSection(t.Sel.Name)
	}

	typ = typesinternal.Unpointer(typ)
	switch t := typ.(type) {
	// Use the first character of the type name as the argument name for builtin types
	case *types.Basic:
		return t.Name()[:1]
	case *types.Slice:
		return paramName(e, t.Elem())
	case *types.Array:
		return paramName(e, t.Elem())
	case *types.Signature:
		return "f"
	case *types.Map:
		return "m"
	case *types.Chan:
		return "ch"
	case *types.Named:
		return lastSection(t.Obj().Name())
	default:
		return lastSection(t.String())
	}
}

// lastSection find the position of the last uppercase letter,
// extract the substring from that point onward,
// and convert it to lowercase.
//
// Example: lastSection("registryManagerFactory") = "factory"
func lastSection(identName string) string {
	lastUpperIndex := -1
	for i, r := range identName {
		if unicode.IsUpper(r) {
			lastUpperIndex = i
		}
	}
	if lastUpperIndex != -1 {
		last := identName[lastUpperIndex:]
		return strings.ToLower(last)
	} else {
		return identName
	}
}


================================================
FILE: gopls/internal/golang/stubmethods/stubmethods.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stubmethods provides the analysis logic for the quick fix
// to "Declare missing methods of TYPE" errors. (The fix logic lives
// in golang.stubMethodsFixer.)
package stubmethods

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typesinternal"

	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/typesutil"
)

// TODO(adonovan): eliminate the confusing Fset parameter; only the
// file name and byte offset of Concrete are needed.

// IfaceStubInfo represents a concrete type
// that wants to stub out an interface type
type IfaceStubInfo struct {
	// Interface is the interface that the client wants to implement.
	// When the interface is defined, the underlying object will be a TypeName.
	// Note that we keep track of types.Object instead of types.Type in order
	// to keep a reference to the declaring object's package and the ast file
	// in the case where the concrete type file requires a new import that happens to be renamed
	// in the interface file.
	// TODO(marwan-at-work): implement interface literals.
	Fset      *token.FileSet // the FileSet used to type-check the types below
	Interface *types.TypeName
	Concrete  typesinternal.NamedOrAlias
	pointer   bool
}

// GetIfaceStubInfo determines whether the "missing method error"
// can be used to deduced what the concrete and interface types are.
//
// TODO(adonovan): this function (and its following 5 helpers) tries
// to deduce a pair of (concrete, interface) types that are related by
// an assignment, either explicitly or through a return statement or
// function call. This is essentially what the refactor/satisfy does,
// more generally. Refactor to share logic, after auditing 'satisfy'
// for safety on ill-typed code.
func GetIfaceStubInfo(fset *token.FileSet, info *types.Info, pgf *parsego.File, pos, end token.Pos) *IfaceStubInfo {
	cur, _ := pgf.Cursor().FindByPos(pos, end)
	for cur := range cur.Enclosing() {
		// TODO: do cur = unparenEnclosing(cur) first, once CL 701035 lands.
		switch cur.ParentEdgeKind() {
		case edge.ValueSpec_Values:
			return fromValueSpec(fset, info, cur)
		case edge.ReturnStmt_Results:
			// An error here may not indicate a real error the user should know about, but it may.
			// Therefore, it would be best to log it out for debugging/reporting purposes instead of ignoring
			// it. However, event.Log takes a context which is not passed via the analysis package.
			// TODO(marwan-at-work): properly log this error.
			si, _ := fromReturnStmt(fset, info, cur)
			return si
		case edge.AssignStmt_Rhs:
			return fromAssignStmt(fset, info, cur)
		case edge.CallExpr_Args:
			// Note that some call expressions don't carry the interface type
			// because they don't point to a function or method declaration elsewhere.
			// For eaxmple, "var Interface = (*Concrete)(nil)". In that case, continue
			// this loop to encounter other possibilities such as *ast.ValueSpec or others.
			si := fromCallExpr(fset, info, cur)
			if si != nil {
				return si
			}
		}
	}
	return nil
}

// Emit writes to out the missing methods of si.Concrete required for it to implement si.Interface
func (si *IfaceStubInfo) Emit(out *bytes.Buffer, qual types.Qualifier) error {
	conc := si.Concrete.Obj()
	// Record all direct methods of the current object
	concreteFuncs := make(map[string]struct{})
	if named, ok := types.Unalias(si.Concrete).(*types.Named); ok {
		for method := range named.Methods() {
			concreteFuncs[method.Name()] = struct{}{}
		}
	}

	var (
		missing []*types.Func
		// Find subset of interface methods that the concrete type lacks.
		ifaceType = si.Interface.Type().Underlying().(*types.Interface)
	)

	for imethod := range ifaceType.Methods() {
		cmethod, index, _ := types.LookupFieldOrMethod(si.Concrete, si.pointer, imethod.Pkg(), imethod.Name())
		if cmethod == nil {
			missing = append(missing, imethod)
			continue
		}

		if _, ok := cmethod.(*types.Var); ok {
			// len(LookupFieldOrMethod.index) = 1 => conflict, >1 => shadow.
			return fmt.Errorf("adding method %s.%s would conflict with (or shadow) existing field",
				conc.Name(), imethod.Name())
		}

		if _, exist := concreteFuncs[imethod.Name()]; exist {
			if !types.Identical(cmethod.Type(), imethod.Type()) {
				return fmt.Errorf("method %s.%s already exists but has the wrong type: got %s, want %s",
					conc.Name(), imethod.Name(), cmethod.Type(), imethod.Type())
			}
			continue
		}

		if len(index) > 0 {
			// len(index) > 0 implies that the current method is already
			// implemented on some embedded object.
			// Do not generate a method if it would result in shadowing, but
			// continue generating other parts of the stub.
			// For example, if some struct A partially implements an interface I
			// and another struct B embeds A, we should not implement methods on
			// B that are already implemented on A, as these would be shadowed
			// methods.
			continue
		}

		missing = append(missing, imethod)
	}
	if len(missing) == 0 {
		return fmt.Errorf("no missing methods found")
	}

	// Format interface name (used only in a comment).
	iface := si.Interface.Name()
	if ipkg := si.Interface.Pkg(); ipkg != nil && ipkg != conc.Pkg() {
		iface = ipkg.Name() + "." + iface
	}

	// Pointer receiver?
	var star string
	if si.pointer {
		star = "*"
	}

	// If there are any that have named receiver, choose the first one.
	// Otherwise, use lowercase for the first letter of the object.
	rn := strings.ToLower(si.Concrete.Obj().Name()[0:1])
	if named, ok := types.Unalias(si.Concrete).(*types.Named); ok {
		for method := range named.Methods() {
			if recv := method.Signature().Recv(); recv.Name() != "" {
				rn = recv.Name()
				break
			}
		}
	}

	// Check for receiver name conflicts
	checkRecvName := func(tuple *types.Tuple) bool {
		for v := range tuple.Variables() {
			if rn == v.Name() {
				return true
			}
		}
		return false
	}

	for index := range missing {
		mrn := rn + " "
		sig := missing[index].Signature()
		if checkRecvName(sig.Params()) || checkRecvName(sig.Results()) {
			mrn = ""
		}

		fmt.Fprintf(out, `// %s implements [%s].
func (%s%s%s%s) %s%s {
	panic("unimplemented")
}
`,
			missing[index].Name(),
			iface,
			mrn,
			star,
			si.Concrete.Obj().Name(),
			typesutil.FormatTypeParams(si.Concrete.TypeParams()),
			missing[index].Name(),
			strings.TrimPrefix(types.TypeString(missing[index].Type(), qual), "func"))
	}
	return nil
}

// fromCallExpr tries to find an *ast.CallExpr's function declaration and
// analyzes a function call's signature against the passed in call argument to deduce
// the concrete and interface types.
func fromCallExpr(fset *token.FileSet, info *types.Info, curCallArg inspector.Cursor) *IfaceStubInfo {

	call := curCallArg.Parent().Node().(*ast.CallExpr)
	arg := curCallArg.Node().(ast.Expr)

	concType, pointer := concreteType(arg, info)
	if concType == nil || concType.Obj().Pkg() == nil {
		return nil
	}
	tv, ok := info.Types[call.Fun]
	if !ok {
		return nil
	}
	sig, ok := types.Unalias(tv.Type).(*types.Signature)
	if !ok {
		return nil
	}

	argIdx := curCallArg.ParentEdgeIndex()
	var paramType types.Type
	if sig.Variadic() && argIdx >= sig.Params().Len()-1 {
		v := sig.Params().At(sig.Params().Len() - 1)
		if s, _ := v.Type().(*types.Slice); s != nil {
			paramType = s.Elem()
		}
	} else if argIdx < sig.Params().Len() {
		paramType = sig.Params().At(argIdx).Type()
	}
	if paramType == nil {
		return nil // A type error prevents us from determining the param type.
	}
	iface := ifaceObjFromType(paramType)
	if iface == nil {
		return nil
	}
	return &IfaceStubInfo{
		Fset:      fset,
		Concrete:  concType,
		pointer:   pointer,
		Interface: iface,
	}
}

// fromReturnStmt analyzes a "return" statement to extract
// a concrete type that is trying to be returned as an interface type.
//
// For example, func() io.Writer { return myType{} }
// would return StubIfaceInfo with the interface being io.Writer and the concrete type being myType{}.
func fromReturnStmt(fset *token.FileSet, info *types.Info, curResult inspector.Cursor) (*IfaceStubInfo, error) {
	concType, pointer := concreteType(curResult.Node().(ast.Expr), info)
	if concType == nil || concType.Obj().Pkg() == nil {
		return nil, nil // result is not a named or *named or alias thereof
	}
	// Inv: the return is not a spread return,
	// such as "return f()" where f() has tuple type.
	conc := concType.Obj()
	if conc.Parent() != conc.Pkg().Scope() {
		return nil, fmt.Errorf("local type %q cannot be stubbed", conc.Name())
	}

	sig := typesutil.EnclosingSignature(curResult, info)
	if sig == nil {
		// Either curResult is not within a function (incontheivable?),
		// or the function's type information is missing (in which case
		// EnclosingSignature will have called bug.Report).
		// Don't report a second bug here.
		// See https://go.dev/issue/70666.
		return nil, fmt.Errorf("internal error: return statement lacks type information or enclosing function (issue 70666)")
	}
	rets := sig.Results()
	// The return operands and function results must match.
	// (Spread returns were rejected earlier.)
	ret := curResult.Parent().Node().(*ast.ReturnStmt)
	if rets.Len() != len(ret.Results) {
		return nil, fmt.Errorf("%d-operand return statement in %d-result function",
			len(ret.Results),
			rets.Len())
	}
	iface := ifaceObjFromType(rets.At(curResult.ParentEdgeIndex()).Type())
	if iface == nil {
		return nil, nil
	}
	return &IfaceStubInfo{
		Fset:      fset,
		Concrete:  concType,
		pointer:   pointer,
		Interface: iface,
	}, nil
}

// fromValueSpec returns *StubIfaceInfo from a variable declaration such as
// var x io.Writer = &T{}
func fromValueSpec(fset *token.FileSet, info *types.Info, curValue inspector.Cursor) *IfaceStubInfo {

	rhs := curValue.Node().(ast.Expr)
	spec := curValue.Parent().Node().(*ast.ValueSpec)

	// Possible implicit/explicit conversion to interface type?
	ifaceNode := spec.Type // var _ myInterface = ...
	if call, ok := rhs.(*ast.CallExpr); ok && ifaceNode == nil && len(call.Args) == 1 {
		// var _ = myInterface(v)
		ifaceNode = call.Fun
		rhs = call.Args[0]
	}
	concType, pointer := concreteType(rhs, info)
	if concType == nil || concType.Obj().Pkg() == nil {
		return nil
	}
	conc := concType.Obj()
	if conc.Parent() != conc.Pkg().Scope() {
		return nil
	}

	ifaceObj := ifaceType(ifaceNode, info)
	if ifaceObj == nil {
		return nil
	}
	return &IfaceStubInfo{
		Fset:      fset,
		Concrete:  concType,
		Interface: ifaceObj,
		pointer:   pointer,
	}
}

// fromAssignStmt returns *StubIfaceInfo from a variable assignment such as
// var x io.Writer
// x = &T{}
func fromAssignStmt(fset *token.FileSet, info *types.Info, curRhs inspector.Cursor) *IfaceStubInfo {
	// The interface conversion error in an assignment is against the RHS:
	//
	//      var x io.Writer
	//      x = &T{} // error: missing method
	//          ^^^^

	assign := curRhs.Parent().Node().(*ast.AssignStmt)
	lhs, rhs := assign.Lhs[curRhs.ParentEdgeIndex()], curRhs.Node().(ast.Expr)

	ifaceObj := ifaceType(lhs, info)
	if ifaceObj == nil {
		return nil
	}
	concType, pointer := concreteType(rhs, info)
	if concType == nil || concType.Obj().Pkg() == nil {
		return nil
	}
	conc := concType.Obj()
	if conc.Parent() != conc.Pkg().Scope() {
		return nil
	}
	return &IfaceStubInfo{
		Fset:      fset,
		Concrete:  concType,
		Interface: ifaceObj,
		pointer:   pointer,
	}
}

// ifaceType returns the named interface type to which e refers, if any.
func ifaceType(e ast.Expr, info *types.Info) *types.TypeName {
	tv, ok := info.Types[e]
	if !ok {
		return nil
	}
	return ifaceObjFromType(tv.Type)
}

func ifaceObjFromType(t types.Type) *types.TypeName {
	named, ok := types.Unalias(t).(*types.Named)
	if !ok {
		return nil
	}
	if !types.IsInterface(named) {
		return nil
	}
	// Interfaces defined in the "builtin" package return nil a Pkg().
	// But they are still real interfaces that we need to make a special case for.
	// Therefore, protect gopls from panicking if a new interface type was added in the future.
	if named.Obj().Pkg() == nil && named.Obj().Name() != "error" {
		return nil
	}
	return named.Obj()
}

// concreteType tries to extract the *types.Named that defines
// the concrete type given the ast.Expr where the "missing method"
// or "conversion" errors happened. If the concrete type is something
// that cannot have methods defined on it (such as basic types), this
// method will return a nil *types.Named. The second return parameter
// is a boolean that indicates whether the concreteType was defined as a
// pointer or value.
func concreteType(e ast.Expr, info *types.Info) (*types.Named, bool) {
	tv, ok := info.Types[e]
	if !ok {
		return nil, false
	}
	typ := tv.Type
	ptr, isPtr := types.Unalias(typ).(*types.Pointer)
	if isPtr {
		typ = ptr.Elem()
	}
	named, ok := types.Unalias(typ).(*types.Named)
	if !ok {
		return nil, false
	}
	return named, isPtr
}


================================================
FILE: gopls/internal/golang/symbols.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
)

func DocumentSymbols(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.DocumentSymbol, error) {
	ctx, done := event.Start(ctx, "golang.DocumentSymbols")
	defer done()

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, fmt.Errorf("getting file for DocumentSymbols: %w", err)
	}

	// Build symbols for file declarations. When encountering a declaration with
	// errors (typically because positions are invalid), we skip the declaration
	// entirely. VS Code fails to show any symbols if one of the top-level
	// symbols is missing position information.
	var symbols []protocol.DocumentSymbol
	for _, decl := range pgf.File.Decls {
		switch decl := decl.(type) {
		case *ast.FuncDecl:
			if decl.Name.Name == "_" {
				continue
			}
			fs, err := funcSymbol(pgf.Mapper, pgf.Tok, decl)
			if err == nil {
				// If function is a method, prepend the type of the method.
				if decl.Recv != nil && len(decl.Recv.List) > 0 {
					fs.Name = fmt.Sprintf("(%s).%s", types.ExprString(decl.Recv.List[0].Type), fs.Name)
				}
				symbols = append(symbols, fs)
			}
		case *ast.GenDecl:
			for _, spec := range decl.Specs {
				switch spec := spec.(type) {
				case *ast.TypeSpec:
					if spec.Name.Name == "_" {
						continue
					}
					ts, err := typeSymbol(pgf.Mapper, pgf.Tok, spec)
					if err == nil {
						symbols = append(symbols, ts)
					}
				case *ast.ValueSpec:
					for _, name := range spec.Names {
						if name.Name == "_" {
							continue
						}
						vs, err := varSymbol(pgf.Mapper, pgf.Tok, spec, name, decl.Tok == token.CONST)
						if err == nil {
							symbols = append(symbols, vs)
						}
					}
				}
			}
		}
	}
	return symbols, nil
}

// PackageSymbols returns a list of symbols in the narrowest package for the given file (specified
// by its URI).
// Methods with receivers are stored as children under the symbol for their receiver type.
// The PackageSymbol data type contains the same fields as protocol.DocumentSymbol, with
// an additional int field "File" that stores the index of that symbol's file in the
// PackageSymbolsResult.Files.
// Symbols are gathered using syntax rather than type information because type checking is
// significantly slower. Syntax information provides enough value to the user without
// causing a lag when loading symbol information across different files.
func PackageSymbols(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) (command.PackageSymbolsResult, error) {
	ctx, done := event.Start(ctx, "source.PackageSymbols")
	defer done()

	pkgFiles := []protocol.DocumentURI{uri}

	// golang/vscode-go#3681: do our best if the file is not in a package.
	// TODO(rfindley): revisit this in the future once there is more graceful
	// handling in VS Code.
	if mp, err := snapshot.NarrowestMetadataForFile(ctx, uri); err == nil {
		pkgFiles = mp.CompiledGoFiles
	}

	var (
		pkgName           string
		symbols           []command.PackageSymbol
		receiverToMethods = make(map[string][]command.PackageSymbol) // receiver name -> methods
		typeSymbolToIdx   = make(map[string]int)                     // type name -> index in symbols
	)
	for fidx, f := range pkgFiles {
		fh, err := snapshot.ReadFile(ctx, f)
		if err != nil {
			return command.PackageSymbolsResult{}, err
		}
		pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
		if err != nil {
			return command.PackageSymbolsResult{}, err
		}
		if pkgName == "" && pgf.File != nil && pgf.File.Name != nil {
			pkgName = pgf.File.Name.Name
		}
		for _, decl := range pgf.File.Decls {
			switch decl := decl.(type) {
			case *ast.FuncDecl:
				if decl.Name.Name == "_" {
					continue
				}
				if fs, err := funcSymbol(pgf.Mapper, pgf.Tok, decl); err == nil {
					// If function is a method, prepend the type of the method.
					// Don't add the method as its own symbol; store it so we can
					// add it as a child of the receiver type later
					if decl.Recv != nil && len(decl.Recv.List) > 0 {
						_, rname, _ := astutil.UnpackRecv(decl.Recv.List[0].Type)
						receiverToMethods[rname.String()] = append(receiverToMethods[rname.String()], toPackageSymbol(fidx, fs))
					} else {
						symbols = append(symbols, toPackageSymbol(fidx, fs))
					}
				}
			case *ast.GenDecl:
				for _, spec := range decl.Specs {
					switch spec := spec.(type) {
					case *ast.TypeSpec:
						if spec.Name.Name == "_" {
							continue
						}
						if ts, err := typeSymbol(pgf.Mapper, pgf.Tok, spec); err == nil {
							typeSymbolToIdx[ts.Name] = len(symbols)
							symbols = append(symbols, toPackageSymbol(fidx, ts))
						}
					case *ast.ValueSpec:
						for _, name := range spec.Names {
							if name.Name == "_" {
								continue
							}
							if vs, err := varSymbol(pgf.Mapper, pgf.Tok, spec, name, decl.Tok == token.CONST); err == nil {
								symbols = append(symbols, toPackageSymbol(fidx, vs))
							}
						}
					}
				}
			}
		}
	}
	// Add methods as the child of their receiver type symbol
	for recv, methods := range receiverToMethods {
		if i, ok := typeSymbolToIdx[recv]; ok {
			symbols[i].Children = append(symbols[i].Children, methods...)
		}
	}
	return command.PackageSymbolsResult{
		PackageName: pkgName,
		Files:       pkgFiles,
		Symbols:     symbols,
	}, nil
}

func toPackageSymbol(fileIndex int, s protocol.DocumentSymbol) command.PackageSymbol {
	var res command.PackageSymbol
	res.Name = s.Name
	res.Detail = s.Detail
	res.Kind = s.Kind
	res.Tags = s.Tags
	res.Range = s.Range
	res.SelectionRange = s.SelectionRange

	children := make([]command.PackageSymbol, len(s.Children))
	for i, c := range s.Children {
		children[i] = toPackageSymbol(fileIndex, c)
	}
	res.Children = children

	res.File = fileIndex
	return res
}

func funcSymbol(m *protocol.Mapper, tf *token.File, decl *ast.FuncDecl) (protocol.DocumentSymbol, error) {
	s := protocol.DocumentSymbol{
		Name: decl.Name.Name,
		Kind: protocol.Function,
	}
	if decl.Recv != nil {
		s.Kind = protocol.Method
	}
	var err error
	s.Range, err = m.NodeRange(tf, decl)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	s.SelectionRange, err = m.NodeRange(tf, decl.Name)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	s.Detail = types.ExprString(decl.Type)
	return s, nil
}

func typeSymbol(m *protocol.Mapper, tf *token.File, spec *ast.TypeSpec) (protocol.DocumentSymbol, error) {
	s := protocol.DocumentSymbol{
		Name: spec.Name.Name,
	}
	var err error
	s.Range, err = m.NodeRange(tf, spec)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	s.SelectionRange, err = m.NodeRange(tf, spec.Name)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	s.Kind, s.Detail, s.Children = typeDetails(m, tf, spec.Type)
	return s, nil
}

func typeDetails(m *protocol.Mapper, tf *token.File, typExpr ast.Expr) (kind protocol.SymbolKind, detail string, children []protocol.DocumentSymbol) {
	switch typExpr := typExpr.(type) {
	case *ast.StructType:
		kind = protocol.Struct
		children = fieldListSymbols(m, tf, typExpr.Fields, protocol.Field)
		if len(children) > 0 {
			detail = "struct{...}"
		} else {
			detail = "struct{}"
		}

		// Find interface methods and embedded types.
	case *ast.InterfaceType:
		kind = protocol.Interface
		children = fieldListSymbols(m, tf, typExpr.Methods, protocol.Method)
		if len(children) > 0 {
			detail = "interface{...}"
		} else {
			detail = "interface{}"
		}

	case *ast.FuncType:
		kind = protocol.Function
		detail = types.ExprString(typExpr)

	default:
		kind = protocol.Class // catch-all, for cases where we don't know the kind syntactically
		detail = types.ExprString(typExpr)
	}
	return
}

func fieldListSymbols(m *protocol.Mapper, tf *token.File, fields *ast.FieldList, fieldKind protocol.SymbolKind) []protocol.DocumentSymbol {
	if fields == nil {
		return nil
	}

	var symbols []protocol.DocumentSymbol
	for _, field := range fields.List {
		detail, children := "", []protocol.DocumentSymbol(nil)
		if field.Type != nil {
			_, detail, children = typeDetails(m, tf, field.Type)
		}
		if len(field.Names) == 0 { // embedded interface or struct field
			// By default, use the formatted type details as the name of this field.
			// This handles potentially invalid syntax, as well as type embeddings in
			// interfaces.
			child := protocol.DocumentSymbol{
				Name:     detail,
				Kind:     protocol.Field, // consider all embeddings to be fields
				Children: children,
			}

			// If the field is a valid embedding, promote the type name to field
			// name.
			selection := field.Type
			if id := embeddedIdent(field.Type); id != nil {
				child.Name = id.Name
				child.Detail = detail
				selection = id
			}

			if rng, err := m.NodeRange(tf, field.Type); err == nil {
				child.Range = rng
			}
			if rng, err := m.NodeRange(tf, selection); err == nil {
				child.SelectionRange = rng
			}

			symbols = append(symbols, child)
		} else {
			for _, name := range field.Names {
				child := protocol.DocumentSymbol{
					Name:     name.Name,
					Kind:     fieldKind,
					Detail:   detail,
					Children: children,
				}

				if rng, err := m.NodeRange(tf, field); err == nil {
					child.Range = rng
				}
				if rng, err := m.NodeRange(tf, name); err == nil {
					child.SelectionRange = rng
				}

				symbols = append(symbols, child)
			}
		}

	}
	return symbols
}

func varSymbol(m *protocol.Mapper, tf *token.File, spec *ast.ValueSpec, name *ast.Ident, isConst bool) (protocol.DocumentSymbol, error) {
	s := protocol.DocumentSymbol{
		Name: name.Name,
		Kind: protocol.Variable,
	}
	if isConst {
		s.Kind = protocol.Constant
	}
	var err error
	s.Range, err = m.NodeRange(tf, spec)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	s.SelectionRange, err = m.NodeRange(tf, name)
	if err != nil {
		return protocol.DocumentSymbol{}, err
	}
	if spec.Type != nil { // type may be missing from the syntax
		_, s.Detail, s.Children = typeDetails(m, tf, spec.Type)
	}
	return s, nil
}


================================================
FILE: gopls/internal/golang/type_definition.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/types"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/event"
)

// TypeDefinition handles the textDocument/typeDefinition request for Go files.
func TypeDefinition(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	ctx, done := event.Start(ctx, "golang.TypeDefinition")
	defer done()

	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}
	cur, _, _, _ := astutil.Select(pgf.Cursor(), start, end) // can't fail (start, end are within File)

	// Find innermost enclosing expression that has a type.
	// It needn't be an identifier.
	var (
		info = pkg.TypesInfo()
		t    types.Type
	)
	for cur := range cur.Enclosing() {
		expr, ok := cur.Node().(ast.Expr)
		if !ok {
			continue
		}

		// edge case: switch id := expr.(type) {}
		// id has no type; use expr instead.
		if cur.ParentEdgeKind() == edge.AssignStmt_Lhs &&
			cur.Parent().ParentEdgeKind() == edge.TypeSwitchStmt_Assign {
			expr = cur.Parent().Node().(*ast.AssignStmt).Rhs[0].(*ast.TypeAssertExpr).X
		}

		if id, ok := expr.(*ast.Ident); ok {
			if obj := info.ObjectOf(id); obj != nil {
				t = obj.Type()
			}
		} else {
			t = info.TypeOf(expr)
		}
		if t != nil {
			break
		}
	}
	if t == nil {
		return nil, fmt.Errorf("no enclosing expression has a type")
	}
	tnames := typeToObjects(t)
	if len(tnames) == 0 {
		return nil, fmt.Errorf("cannot find type name(s) from type %s", t)
	}

	var locs []protocol.Location
	for _, t := range tnames {
		loc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, t)
		if err != nil {
			return nil, err
		}
		locs = append(locs, loc)
	}

	return locs, nil
}


================================================
FILE: gopls/internal/golang/type_hierarchy.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"fmt"
	"go/ast"
	"go/types"
	"slices"
	"strings"
	"sync"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/methodsets"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

// Type hierarchy support (using method sets)
//
// TODO(adonovan):
// - Support type hierarchy by signatures (using Kind=Function).
//   As with Implementations by signature matching, needs more UX thought.
//
// - Allow methods too (using Kind=Method)? It's not exactly in the
//   spirit of TypeHierarchy but it would be useful and it's easy
//   enough to support.
//
// - fix pkg=command-line-arguments problem with query initiated at "error" in builtins.go

// PrepareTypeHierarchy returns the TypeHierarchyItems for the types at the selected position.
func PrepareTypeHierarchy(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.TypeHierarchyItem, error) {
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	start, end, err := pgf.RangePos(rng)
	if err != nil {
		return nil, err
	}

	// For now, we require that the selection be a type name.
	cur, ok := pgf.Cursor().FindByPos(start, end)
	if !ok {
		return nil, fmt.Errorf("no enclosing syntax") // can't happen
	}
	id, ok := cur.Node().(*ast.Ident)
	if !ok {
		return nil, fmt.Errorf("not a type name")
	}
	tname, ok := pkg.TypesInfo().ObjectOf(id).(*types.TypeName)
	if !ok {
		return nil, fmt.Errorf("not a type name")
	}

	// Find declaration.
	declLoc, err := ObjectLocation(ctx, pkg.FileSet(), snapshot, tname)
	if err != nil {
		return nil, err
	}

	pkgpath := "builtin"
	if tname.Pkg() != nil {
		pkgpath = tname.Pkg().Path()
	}

	return []protocol.TypeHierarchyItem{{
		Name:           tname.Name(),
		Kind:           cond(types.IsInterface(tname.Type()), protocol.Interface, protocol.Class),
		Detail:         pkgpath,
		URI:            declLoc.URI,
		Range:          declLoc.Range, // (in theory this should be the entire declaration)
		SelectionRange: declLoc.Range,
	}}, nil
}

// Subtypes reports information about subtypes of the selected type.
func Subtypes(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, item protocol.TypeHierarchyItem) ([]protocol.TypeHierarchyItem, error) {
	return relatedTypes(ctx, snapshot, fh, item, methodsets.Subtype)
}

// Supertypes reports information about supertypes of the selected type.
func Supertypes(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, item protocol.TypeHierarchyItem) ([]protocol.TypeHierarchyItem, error) {
	return relatedTypes(ctx, snapshot, fh, item, methodsets.Supertype)
}

// relatedTypes is the common implementation of {Super,Sub}types.
func relatedTypes(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, item protocol.TypeHierarchyItem, rel methodsets.TypeRelation) ([]protocol.TypeHierarchyItem, error) {
	pkg, pgf, err := NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, err
	}
	pos, err := pgf.PositionPos(item.Range.Start)
	if err != nil {
		return nil, err
	}
	cur, _ := pgf.Cursor().FindByPos(pos, pos) // can't fail

	var (
		itemsMu sync.Mutex
		items   []protocol.TypeHierarchyItem
	)
	err = implementationsMsets(ctx, snapshot, pkg, cur, rel, func(pkgpath metadata.PackagePath, name string, abstract bool, loc protocol.Location) {
		if pkgpath == "" {
			pkgpath = "builtin"
		}

		itemsMu.Lock()
		defer itemsMu.Unlock()
		items = append(items, protocol.TypeHierarchyItem{
			Name:           name,
			Kind:           cond(abstract, protocol.Interface, protocol.Class),
			Detail:         string(pkgpath),
			URI:            loc.URI,
			Range:          loc.Range, // (in theory this should be the entire declaration)
			SelectionRange: loc.Range,
		})
	})
	if err != nil {
		return nil, err
	}

	// Sort by (package, name, URI, range) then
	// de-duplicate based on the same 4-tuple
	cmp := func(x, y protocol.TypeHierarchyItem) int {
		if d := strings.Compare(x.Detail, y.Detail); d != 0 {
			// Rank the original item's package first.
			if d := boolCompare(x.Detail == item.Detail, y.Detail == item.Detail); d != 0 {
				return -d
			}
			return d
		}
		if d := strings.Compare(x.Name, y.Name); d != 0 {
			return d
		}
		if d := strings.Compare(string(x.URI), string(y.URI)); d != 0 {
			return d
		}
		return protocol.CompareRange(x.SelectionRange, y.Range)
	}
	slices.SortFunc(items, cmp)
	eq := func(x, y protocol.TypeHierarchyItem) bool { return cmp(x, y) == 0 }
	items = slices.CompactFunc(items, eq)

	return items, nil
}


================================================
FILE: gopls/internal/golang/types_format.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/doc"
	"go/printer"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/typeparams"
)

// FormatType returns the detail and kind for a types.Type.
func FormatType(typ types.Type, qual types.Qualifier) (detail string, kind protocol.CompletionItemKind) {
	typ = typ.Underlying()
	if types.IsInterface(typ) {
		detail = "interface{...}"
		kind = protocol.InterfaceCompletion
	} else if _, ok := typ.(*types.Struct); ok {
		detail = "struct{...}"
		kind = protocol.StructCompletion
	} else {
		detail = types.TypeString(typ, qual)
		kind = protocol.ClassCompletion
	}
	return detail, kind
}

type signature struct {
	name, doc                   string
	typeParams, params, results []string
	variadic                    bool
	needResultParens            bool
}

func (s *signature) Format() string {
	var b strings.Builder
	b.WriteByte('(')
	for i, p := range s.params {
		if i > 0 {
			b.WriteString(", ")
		}
		b.WriteString(p)
	}
	b.WriteByte(')')

	// Add space between parameters and results.
	if len(s.results) > 0 {
		b.WriteByte(' ')
	}
	if s.needResultParens {
		b.WriteByte('(')
	}
	for i, r := range s.results {
		if i > 0 {
			b.WriteString(", ")
		}
		b.WriteString(r)
	}
	if s.needResultParens {
		b.WriteByte(')')
	}
	return b.String()
}

func (s *signature) TypeParams() []string {
	return s.typeParams
}

func (s *signature) Params() []string {
	return s.params
}

// NewBuiltinSignature returns signature for the builtin object with a given
// name, if a builtin object with the name exists.
func NewBuiltinSignature(ctx context.Context, s *cache.Snapshot, name string) (*signature, error) {
	builtin, err := s.BuiltinFile(ctx)
	if err != nil {
		return nil, err
	}
	obj := builtin.File.Scope.Lookup(name)
	if obj == nil {
		return nil, fmt.Errorf("no builtin object for %s", name)
	}
	decl, ok := obj.Decl.(*ast.FuncDecl)
	if !ok {
		return nil, fmt.Errorf("no function declaration for builtin: %s", name)
	}
	if decl.Type == nil {
		return nil, fmt.Errorf("no type for builtin decl %s", decl.Name)
	}
	var variadic bool
	if decl.Type.Params.List != nil {
		numParams := len(decl.Type.Params.List)
		lastParam := decl.Type.Params.List[numParams-1]
		if _, ok := lastParam.Type.(*ast.Ellipsis); ok {
			variadic = true
		}
	}
	fset := tokeninternal.FileSetFor(builtin.Tok)
	params, _ := formatFieldList(ctx, fset, decl.Type.Params, variadic)
	results, needResultParens := formatFieldList(ctx, fset, decl.Type.Results, false)
	d := decl.Doc.Text()
	switch s.Options().HoverKind {
	case settings.SynopsisDocumentation:
		d = doc.Synopsis(d)
	case settings.NoDocumentation:
		d = ""
	}
	return &signature{
		doc:              d,
		name:             name,
		needResultParens: needResultParens,
		params:           params,
		results:          results,
		variadic:         variadic,
	}, nil
}

// replacer replaces some synthetic "type classes" used in the builtin file
// with their most common constituent type.
var replacer = strings.NewReplacer(
	`ComplexType`, `complex128`,
	`FloatType`, `float64`,
	`IntegerType`, `int`,
)

func formatFieldList(ctx context.Context, fset *token.FileSet, list *ast.FieldList, variadic bool) ([]string, bool) {
	if list == nil {
		return nil, false
	}
	var writeResultParens bool
	var result []string
	for i := 0; i < len(list.List); i++ {
		if i >= 1 {
			writeResultParens = true
		}
		p := list.List[i]
		cfg := printer.Config{Mode: printer.UseSpaces | printer.TabIndent, Tabwidth: 4}
		b := &bytes.Buffer{}
		if err := cfg.Fprint(b, fset, p.Type); err != nil {
			event.Error(ctx, fmt.Sprintf("error printing type %s", types.ExprString(p.Type)), err)
			continue
		}
		typ := replacer.Replace(b.String())
		if len(p.Names) == 0 {
			result = append(result, typ)
		}
		for _, name := range p.Names {
			if name.Name != "" {
				if i == 0 {
					writeResultParens = true
				}
				result = append(result, fmt.Sprintf("%s %s", name.Name, typ))
			} else {
				result = append(result, typ)
			}
		}
	}
	if variadic {
		result[len(result)-1] = strings.Replace(result[len(result)-1], "[]", "...", 1)
	}
	return result, writeResultParens
}

// NewSignature returns formatted signature for a types.Signature struct.
func NewSignature(ctx context.Context, s *cache.Snapshot, pkg *cache.Package, sig *types.Signature, comment *ast.CommentGroup, qual types.Qualifier, mq MetadataQualifier) (*signature, error) {
	var tparams []string
	tpList := sig.TypeParams()
	for tparam := range tpList.TypeParams() {
		// TODO: is it possible to reuse the logic from FormatVarType here?
		s := tparam.Obj().Name() + " " + tparam.Constraint().String()
		tparams = append(tparams, s)
	}

	params := make([]string, 0, sig.Params().Len())
	for i := 0; i < sig.Params().Len(); i++ {
		el := sig.Params().At(i)
		typ, err := FormatVarType(ctx, s, pkg, el, qual, mq)
		if err != nil {
			return nil, err
		}
		if sig.Variadic() && i == sig.Params().Len()-1 {
			typ = strings.Replace(typ, "[]", "...", 1)
		}
		p := typ
		if el.Name() != "" {
			p = el.Name() + " " + typ
		}
		params = append(params, p)
	}

	var needResultParens bool
	results := make([]string, 0, sig.Results().Len())
	for i := 0; i < sig.Results().Len(); i++ {
		if i >= 1 {
			needResultParens = true
		}
		el := sig.Results().At(i)
		typ, err := FormatVarType(ctx, s, pkg, el, qual, mq)
		if err != nil {
			return nil, err
		}
		if el.Name() == "" {
			results = append(results, typ)
		} else {
			if i == 0 {
				needResultParens = true
			}
			results = append(results, el.Name()+" "+typ)
		}
	}
	var d string
	if comment != nil {
		d = comment.Text()
	}
	switch s.Options().HoverKind {
	case settings.SynopsisDocumentation:
		d = doc.Synopsis(d)
	case settings.NoDocumentation:
		d = ""
	}
	return &signature{
		doc:              d,
		typeParams:       tparams,
		params:           params,
		results:          results,
		variadic:         sig.Variadic(),
		needResultParens: needResultParens,
	}, nil
}

// We look for 'invalidTypeString' to determine if we can use the fast path for
// FormatVarType.
var invalidTypeString = types.Typ[types.Invalid].String()

// FormatVarType formats a *types.Var, accounting for type aliases.
// To do this, it looks in the AST of the file in which the object is declared.
// On any errors, it always falls back to types.TypeString.
//
// TODO(rfindley): this function could return the actual name used in syntax,
// for better parameter names.
func FormatVarType(ctx context.Context, snapshot *cache.Snapshot, srcpkg *cache.Package, obj *types.Var, qual types.Qualifier, mq MetadataQualifier) (string, error) {
	typeString := types.TypeString(obj.Type(), qual)
	// Fast path: if the type string does not contain 'invalid type', we no
	// longer need to do any special handling, thanks to materialized aliases in
	// Go 1.23+.
	//
	// Unfortunately, due to the handling of invalid types, we can't quite delete
	// the rather complicated preexisting logic of FormatVarType--it isn't an
	// acceptable regression to start printing "invalid type" in completion or
	// signature help. strings.Contains is conservative: the type string of a
	// valid type may actually contain "invalid type" (due to struct tags or
	// field formatting), but such cases should be exceedingly rare.
	if !strings.Contains(typeString, invalidTypeString) {
		return typeString, nil
	}

	// TODO(rfindley): This looks wrong. The previous comment said:
	// "If the given expr refers to a type parameter, then use the
	// object's Type instead of the type parameter declaration. This helps
	// format the instantiated type as opposed to the original undeclared
	// generic type".
	//
	// But of course, if obj is a type param, we are formatting a generic type
	// and not an instantiated type. Handling for instantiated types must be done
	// at a higher level.
	//
	// Left this during refactoring in order to preserve pre-existing logic.
	if typeparams.IsTypeParam(obj.Type()) {
		return typeString, nil
	}

	if isBuiltin(obj) {
		// This is defensive, though it is extremely unlikely we'll ever have a
		// builtin var.
		return typeString, nil
	}

	// TODO(rfindley): parsing to produce candidates can be costly; consider
	// using faster methods.
	targetpgf, pos, err := parseFull(ctx, snapshot, srcpkg.FileSet(), obj)
	if err != nil {
		return "", err // e.g. ctx cancelled
	}

	targetMeta := findFileInDeps(snapshot, srcpkg.Metadata(), targetpgf.URI)
	if targetMeta == nil {
		// If we have an object from type-checking, it should exist in a file in
		// the forward transitive closure.
		return "", bug.Errorf("failed to find file %q in deps of %q", targetpgf.URI, srcpkg.Metadata().ID)
	}

	decl, spec, field := findDeclInfo([]*ast.File{targetpgf.File}, pos)

	// We can't handle type parameters correctly, so we fall back on TypeString
	// for parameterized decls.
	if decl, _ := decl.(*ast.FuncDecl); decl != nil {
		if decl.Type.TypeParams.NumFields() > 0 {
			return typeString, nil // in generic function
		}
		if decl.Recv != nil && len(decl.Recv.List) > 0 {
			rtype := decl.Recv.List[0].Type
			if e, ok := rtype.(*ast.StarExpr); ok {
				rtype = e.X
			}
			if x, _, _, _ := typeparams.UnpackIndexExpr(rtype); x != nil {
				return typeString, nil // in method of generic type
			}
		}
	}
	if spec, _ := spec.(*ast.TypeSpec); spec != nil && spec.TypeParams.NumFields() > 0 {
		return typeString, nil // in generic type decl
	}

	if field == nil {
		// TODO(rfindley): we should never reach here from an ordinary var, so
		// should probably return an error here.
		return typeString, nil
	}
	expr := field.Type

	rq := requalifier(snapshot, targetpgf.File, targetMeta, mq)

	// The type names in the AST may not be correctly qualified.
	// Determine the package name to use based on the package that originated
	// the query and the package in which the type is declared.
	// We then qualify the value by cloning the AST node and editing it.
	expr = qualifyTypeExpr(expr, rq)

	// If the request came from a different package than the one in which the
	// types are defined, we may need to modify the qualifiers.
	return formatNodeFile(targetpgf.Tok, expr), nil
}

// qualifyTypeExpr clones the type expression expr after re-qualifying type
// names using the given function, which accepts the current syntactic
// qualifier (possibly "" for unqualified idents), and returns a new qualifier
// (again, possibly "" if the identifier should be unqualified).
//
// The resulting expression may be inaccurate: without type-checking we don't
// properly account for "." imported identifiers or builtins.
//
// TODO(rfindley): add many more tests for this function.
func qualifyTypeExpr(expr ast.Expr, qf func(string) string) ast.Expr {
	switch expr := expr.(type) {
	case *ast.ArrayType:
		return &ast.ArrayType{
			Lbrack: expr.Lbrack,
			Elt:    qualifyTypeExpr(expr.Elt, qf),
			Len:    expr.Len,
		}

	case *ast.BinaryExpr:
		if expr.Op != token.OR {
			return expr
		}
		return &ast.BinaryExpr{
			X:     qualifyTypeExpr(expr.X, qf),
			OpPos: expr.OpPos,
			Op:    expr.Op,
			Y:     qualifyTypeExpr(expr.Y, qf),
		}

	case *ast.ChanType:
		return &ast.ChanType{
			Arrow: expr.Arrow,
			Begin: expr.Begin,
			Dir:   expr.Dir,
			Value: qualifyTypeExpr(expr.Value, qf),
		}

	case *ast.Ellipsis:
		return &ast.Ellipsis{
			Ellipsis: expr.Ellipsis,
			Elt:      qualifyTypeExpr(expr.Elt, qf),
		}

	case *ast.FuncType:
		return &ast.FuncType{
			Func:    expr.Func,
			Params:  qualifyFieldList(expr.Params, qf),
			Results: qualifyFieldList(expr.Results, qf),
		}

	case *ast.Ident:
		// Unqualified type (builtin, package local, or dot-imported).

		// Don't qualify names that look like builtins.
		//
		// Without type-checking this may be inaccurate. It could be made accurate
		// by doing syntactic object resolution for the entire package, but that
		// does not seem worthwhile and we generally want to avoid using
		// ast.Object, which may be inaccurate.
		if obj := types.Universe.Lookup(expr.Name); obj != nil {
			return expr
		}

		newName := qf("")
		if newName != "" {
			return &ast.SelectorExpr{
				X: &ast.Ident{
					NamePos: expr.Pos(),
					Name:    newName,
				},
				Sel: expr,
			}
		}
		return expr

	case *ast.IndexExpr:
		return &ast.IndexExpr{
			X:      qualifyTypeExpr(expr.X, qf),
			Lbrack: expr.Lbrack,
			Index:  qualifyTypeExpr(expr.Index, qf),
			Rbrack: expr.Rbrack,
		}

	case *ast.IndexListExpr:
		indices := make([]ast.Expr, len(expr.Indices))
		for i, idx := range expr.Indices {
			indices[i] = qualifyTypeExpr(idx, qf)
		}
		return &ast.IndexListExpr{
			X:       qualifyTypeExpr(expr.X, qf),
			Lbrack:  expr.Lbrack,
			Indices: indices,
			Rbrack:  expr.Rbrack,
		}

	case *ast.InterfaceType:
		return &ast.InterfaceType{
			Interface:  expr.Interface,
			Methods:    qualifyFieldList(expr.Methods, qf),
			Incomplete: expr.Incomplete,
		}

	case *ast.MapType:
		return &ast.MapType{
			Map:   expr.Map,
			Key:   qualifyTypeExpr(expr.Key, qf),
			Value: qualifyTypeExpr(expr.Value, qf),
		}

	case *ast.ParenExpr:
		return &ast.ParenExpr{
			Lparen: expr.Lparen,
			Rparen: expr.Rparen,
			X:      qualifyTypeExpr(expr.X, qf),
		}

	case *ast.SelectorExpr:
		if id, ok := expr.X.(*ast.Ident); ok {
			// qualified type
			newName := qf(id.Name)
			if newName == "" {
				return expr.Sel
			}
			return &ast.SelectorExpr{
				X: &ast.Ident{
					NamePos: id.NamePos,
					Name:    newName,
				},
				Sel: expr.Sel,
			}
		}
		return expr

	case *ast.StarExpr:
		return &ast.StarExpr{
			Star: expr.Star,
			X:    qualifyTypeExpr(expr.X, qf),
		}

	case *ast.StructType:
		return &ast.StructType{
			Struct:     expr.Struct,
			Fields:     qualifyFieldList(expr.Fields, qf),
			Incomplete: expr.Incomplete,
		}

	default:
		return expr
	}
}

func qualifyFieldList(fl *ast.FieldList, qf func(string) string) *ast.FieldList {
	if fl == nil {
		return nil
	}
	if fl.List == nil {
		return &ast.FieldList{
			Closing: fl.Closing,
			Opening: fl.Opening,
		}
	}
	list := make([]*ast.Field, 0, len(fl.List))
	for _, f := range fl.List {
		list = append(list, &ast.Field{
			Comment: f.Comment,
			Doc:     f.Doc,
			Names:   f.Names,
			Tag:     f.Tag,
			Type:    qualifyTypeExpr(f.Type, qf),
		})
	}
	return &ast.FieldList{
		Closing: fl.Closing,
		Opening: fl.Opening,
		List:    list,
	}
}


================================================
FILE: gopls/internal/golang/undeclared.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/token"
	"go/types"
	"strings"
	"unicode"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/util/cursorutil"
	"golang.org/x/tools/gopls/internal/util/typesutil"
	"golang.org/x/tools/internal/typesinternal"
)

// The prefix for this error message changed in Go 1.20.
var undeclaredNamePrefixes = []string{"undeclared name: ", "undefined: "}

// undeclaredFixTitle generates a code action title for "undeclared name" errors,
// suggesting the creation of the missing variable or function if applicable.
func undeclaredFixTitle(curId inspector.Cursor, errMsg string) string {
	// Extract symbol name from error.
	var name string
	for _, prefix := range undeclaredNamePrefixes {
		if !strings.HasPrefix(errMsg, prefix) {
			continue
		}
		name = strings.TrimPrefix(errMsg, prefix)
	}
	ident, ok := curId.Node().(*ast.Ident)
	if !ok || ident.Name != name {
		return ""
	}
	// TODO: support create undeclared field
	if _, ok := curId.Parent().Node().(*ast.SelectorExpr); ok {
		return ""
	}

	// Undeclared quick fixes only work in function bodies.
	block, _ := cursorutil.FirstEnclosing[*ast.BlockStmt](curId)
	if block == nil {
		return ""
	}

	// Offer a fix.
	noun := cond(curId.ParentEdgeKind() == edge.CallExpr_Fun, "function", "variable")
	return fmt.Sprintf("Create %s %s", noun, name)
}

// createUndeclared generates a suggested declaration for an undeclared variable or function.
func createUndeclared(pkg *cache.Package, pgf *parsego.File, start, end token.Pos) (*token.FileSet, *analysis.SuggestedFix, error) {
	var (
		fset = pkg.FileSet()
		info = pkg.TypesInfo()
		file = pgf.File
		pos  = start // don't use end
	)
	curId, _ := pgf.Cursor().FindByPos(pos, pos)
	ident, ok := curId.Node().(*ast.Ident)
	if !ok {
		return nil, nil, fmt.Errorf("no identifier found")
	}

	// Check for a possible call expression, in which case we should add a
	// new function declaration.
	if curId.ParentEdgeKind() == edge.CallExpr_Fun {
		return newFunctionDeclaration(curId, file, pkg.Types(), info, fset)
	}
	// We should insert the new declaration before the
	// first occurrence of the undefined ident.
	var curFirstRef inspector.Cursor // *ast.Ident

	// Search from enclosing FuncDecl to first use, since we can not use := syntax outside function.
	// Adds the missing colon under the following conditions:
	// 1) parent node must be an *ast.AssignStmt with Tok set to token.ASSIGN.
	// 2) ident must not be self assignment.
	//
	// For example, we should not add a colon when
	// a = a + 1
	// ^   ^ cursor here
	_, curFuncDecl := cursorutil.FirstEnclosing[*ast.FuncDecl](curId)
	for curRef := range curFuncDecl.Preorder((*ast.Ident)(nil)) {
		n := curRef.Node().(*ast.Ident)
		if n.Name == ident.Name && info.ObjectOf(n) == nil {
			if curRef.ParentEdgeKind() == edge.AssignStmt_Lhs {
				assign := curRef.Parent().Node().(*ast.AssignStmt)
				if assign.Tok == token.ASSIGN && !referencesIdent(info, assign, ident) {
					// replace = with :=
					return fset, &analysis.SuggestedFix{
						TextEdits: []analysis.TextEdit{{
							Pos:     assign.TokPos,
							End:     assign.TokPos,
							NewText: []byte(":"),
						}},
					}, nil
				}
			}
			curFirstRef = curRef
			break
		}
	}

	// firstRef should never be nil; at least one ident at cursor
	// position should be found. But be defensive.
	if !curFirstRef.Valid() {
		return nil, nil, fmt.Errorf("no identifier found")
	}
	insertPos, err := stmtToInsertVarBefore(curFirstRef, nil)
	if err != nil {
		return nil, nil, fmt.Errorf("could not locate insertion point: %v", err)
	}
	indent, err := pgf.Indentation(insertPos)
	if err != nil {
		return nil, nil, err
	}
	typs := typesutil.TypesFromContext(info, curId)
	if typs == nil {
		// Default to 0.
		typs = []types.Type{types.Typ[types.Int]}
	}
	expr, _ := typesinternal.ZeroExpr(typs[0], typesinternal.FileQualifier(file, pkg.Types()))
	assignStmt := &ast.AssignStmt{
		Lhs: []ast.Expr{ast.NewIdent(ident.Name)},
		Tok: token.DEFINE,
		Rhs: []ast.Expr{expr},
	}
	var buf bytes.Buffer
	if err := format.Node(&buf, fset, assignStmt); err != nil {
		return nil, nil, err
	}
	newLineIndent := "\n" + indent
	assignment := strings.ReplaceAll(buf.String(), "\n", newLineIndent) + newLineIndent

	return fset, &analysis.SuggestedFix{
		TextEdits: []analysis.TextEdit{
			{
				Pos:     insertPos,
				End:     insertPos,
				NewText: []byte(assignment),
			},
		},
	}, nil
}

// referencesIdent checks whether the given undefined ident appears in the right-hand side
// of an assign statement
func referencesIdent(info *types.Info, assign *ast.AssignStmt, ident *ast.Ident) bool {
	for _, rhs := range assign.Rhs {
		for n := range ast.Preorder(rhs) {
			if id, ok := n.(*ast.Ident); ok &&
				id.Name == ident.Name && info.Uses[id] == nil {
				return true
			}
		}
	}
	return false
}

// newFunctionDeclaration returns a suggested declaration for the ident identified by curId
// curId always points at an ast.Ident at the CallExpr_Fun edge.
func newFunctionDeclaration(curId inspector.Cursor, file *ast.File, pkg *types.Package, info *types.Info, fset *token.FileSet) (*token.FileSet, *analysis.SuggestedFix, error) {

	id := curId.Node().(*ast.Ident)
	call := curId.Parent().Node().(*ast.CallExpr)

	// Find the enclosing function, so that we can add the new declaration
	// below.
	funcdecl, _ := cursorutil.FirstEnclosing[*ast.FuncDecl](curId)
	if funcdecl == nil {
		// TODO(rstambler): Support the situation when there is no enclosing
		// function.
		return nil, nil, fmt.Errorf("no enclosing function found: %v", curId)
	}

	pos := funcdecl.End()

	var paramNames []string
	var paramTypes []types.Type
	// keep track of all param names to later ensure uniqueness
	nameCounts := map[string]int{}
	for _, arg := range call.Args {
		typ := info.TypeOf(arg)
		if typ == nil {
			return nil, nil, fmt.Errorf("unable to determine type for %s", arg)
		}

		switch t := typ.(type) {
		// this is the case where another function call returning multiple
		// results is used as an argument
		case *types.Tuple:
			n := t.Len()
			for i := range n {
				name := typeToArgName(t.At(i).Type())
				nameCounts[name]++

				paramNames = append(paramNames, name)
				paramTypes = append(paramTypes, types.Default(t.At(i).Type()))
			}

		default:
			// does the argument have a name we can reuse?
			// only happens in case of a *ast.Ident
			var name string
			if ident, ok := arg.(*ast.Ident); ok {
				name = ident.Name
			}

			if name == "" {
				name = typeToArgName(typ)
			}

			nameCounts[name]++

			paramNames = append(paramNames, name)
			paramTypes = append(paramTypes, types.Default(typ))
		}
	}

	for n, c := range nameCounts {
		// Any names we saw more than once will need a unique suffix added
		// on. Reset the count to 1 to act as the suffix for the first
		// occurrence of that name.
		if c >= 2 {
			nameCounts[n] = 1
		} else {
			delete(nameCounts, n)
		}
	}

	params := &ast.FieldList{}
	qual := typesinternal.FileQualifier(file, pkg)
	for i, name := range paramNames {
		if suffix, repeats := nameCounts[name]; repeats {
			nameCounts[name]++
			name = fmt.Sprintf("%s%d", name, suffix)
		}

		// only worth checking after previous param in the list
		if i > 0 {
			// if type of parameter at hand is the same as the previous one,
			// add it to the previous param list of identifiers so to have:
			//  (s1, s2 string)
			// and not
			//  (s1 string, s2 string)
			if paramTypes[i] == paramTypes[i-1] {
				params.List[len(params.List)-1].Names = append(params.List[len(params.List)-1].Names, ast.NewIdent(name))
				continue
			}
		}

		params.List = append(params.List, &ast.Field{
			Names: []*ast.Ident{
				ast.NewIdent(name),
			},
			Type: typesinternal.TypeExpr(paramTypes[i], qual),
		})
	}

	rets := &ast.FieldList{}
	retTypes := typesutil.TypesFromContext(info, curId.Parent())
	for _, rt := range retTypes {
		rets.List = append(rets.List, &ast.Field{
			Type: typesinternal.TypeExpr(rt, qual),
		})
	}

	decl := &ast.FuncDecl{
		Name: ast.NewIdent(id.Name),
		Type: &ast.FuncType{
			Params:  params,
			Results: rets,
		},
		Body: &ast.BlockStmt{
			List: []ast.Stmt{
				&ast.ExprStmt{
					X: &ast.CallExpr{
						Fun: ast.NewIdent("panic"),
						Args: []ast.Expr{
							&ast.BasicLit{
								Value: `"unimplemented"`,
							},
						},
					},
				},
			},
		},
	}

	b := bytes.NewBufferString("\n\n")
	if err := format.Node(b, fset, decl); err != nil {
		return nil, nil, err
	}
	return fset, &analysis.SuggestedFix{
		TextEdits: []analysis.TextEdit{{
			Pos:     pos,
			End:     pos,
			NewText: b.Bytes(),
		}},
	}, nil
}

func typeToArgName(ty types.Type) string {
	s := types.Default(ty).String()

	switch t := types.Unalias(ty).(type) {
	case *types.Basic:
		// use first letter in type name for basic types
		return s[0:1]
	case *types.Slice:
		// use element type to decide var name for slices
		return typeToArgName(t.Elem())
	case *types.Array:
		// use element type to decide var name for arrays
		return typeToArgName(t.Elem())
	case *types.Chan:
		return "ch"
	}

	s = strings.TrimFunc(s, func(r rune) bool {
		return !unicode.IsLetter(r)
	})

	if s == "error" {
		return "err"
	}

	// remove package (if present)
	// and make first letter lowercase
	a := []rune(s[strings.LastIndexByte(s, '.')+1:])
	a[0] = unicode.ToLower(a[0])
	return string(a)
}


================================================
FILE: gopls/internal/golang/util.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"context"
	"go/ast"
	"go/printer"
	"go/token"
	"go/types"
	"regexp"
	"slices"
	"strings"
	"unicode"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
)

// IsGenerated reads and parses the header of the file denoted by uri
// and reports whether it [ast.IsGenerated].
func IsGenerated(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) bool {
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return false
	}
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header)
	if err != nil {
		return false
	}
	return ast.IsGenerated(pgf.File)
}

// FormatNode returns the "pretty-print" output for an ast node.
func FormatNode(fset *token.FileSet, n ast.Node) string {
	var buf strings.Builder
	if err := printer.Fprint(&buf, fset, n); err != nil {
		// TODO(rfindley): we should use bug.Reportf here.
		// We encounter this during completion.resolveInvalid.
		return ""
	}
	return buf.String()
}

// formatNodeFile is like FormatNode, but requires only the token.File for the
// syntax containing the given ast node.
func formatNodeFile(file *token.File, n ast.Node) string {
	fset := tokeninternal.FileSetFor(file)
	return FormatNode(fset, n)
}

// findFileInDeps finds package metadata containing URI in the transitive
// dependencies of m. When using the Go command, the answer is unique.
func findFileInDeps(s metadata.Source, mp *metadata.Package, uri protocol.DocumentURI) *metadata.Package {
	seen := make(map[PackageID]bool)
	var search func(*metadata.Package) *metadata.Package
	search = func(mp *metadata.Package) *metadata.Package {
		if seen[mp.ID] {
			return nil
		}
		seen[mp.ID] = true
		if slices.Contains(mp.CompiledGoFiles, uri) {
			return mp
		}
		for _, dep := range mp.DepsByPkgPath {
			mp := s.Metadata(dep)
			if mp == nil {
				bug.Reportf("nil metadata for %q", dep)
				continue
			}
			if found := search(mp); found != nil {
				return found
			}
		}
		return nil
	}
	return search(mp)
}

// requalifier returns a function that re-qualifies identifiers and qualified
// identifiers contained in targetFile using the given metadata qualifier.
func requalifier(s metadata.Source, targetFile *ast.File, targetMeta *metadata.Package, mq MetadataQualifier) func(string) string {
	qm := map[string]string{
		"": mq(targetMeta.Name, "", targetMeta.PkgPath),
	}

	// Construct mapping of import paths to their defined or implicit names.
	for _, imp := range targetFile.Imports {
		name, pkgName, impPath, pkgPath := importInfo(s, imp, targetMeta)

		// Re-map the target name for the source file.
		qm[name] = mq(pkgName, impPath, pkgPath)
	}

	return func(name string) string {
		if newName, ok := qm[name]; ok {
			return newName
		}
		return name
	}
}

// A MetadataQualifier is a function that qualifies an identifier declared in a
// package with the given package name, import path, and package path.
//
// In scenarios where metadata is missing the provided PackageName and
// PackagePath may be empty, but ImportPath must always be non-empty.
type MetadataQualifier func(PackageName, ImportPath, PackagePath) string

// MetadataQualifierForFile returns a metadata qualifier that chooses the best
// qualification of an imported package relative to the file f in package with
// metadata m.
func MetadataQualifierForFile(s metadata.Source, f *ast.File, mp *metadata.Package) MetadataQualifier {
	// Record local names for import paths.
	localNames := make(map[ImportPath]string) // local names for imports in f
	for _, imp := range f.Imports {
		name, _, impPath, _ := importInfo(s, imp, mp)
		localNames[impPath] = name
	}

	// Record a package path -> import path mapping.
	inverseDeps := make(map[PackageID]PackagePath)
	for path, id := range mp.DepsByPkgPath {
		inverseDeps[id] = path
	}
	importsByPkgPath := make(map[PackagePath]ImportPath) // best import paths by pkgPath
	for impPath, id := range mp.DepsByImpPath {
		if id == "" {
			continue
		}
		pkgPath := inverseDeps[id]
		_, hasPath := importsByPkgPath[pkgPath]
		_, hasImp := localNames[impPath]
		// In rare cases, there may be multiple import paths with the same package
		// path. In such scenarios, prefer an import path that already exists in
		// the file.
		if !hasPath || hasImp {
			importsByPkgPath[pkgPath] = impPath
		}
	}

	return func(pkgName PackageName, impPath ImportPath, pkgPath PackagePath) string {
		// If supplied, translate the package path to an import path in the source
		// package.
		if pkgPath != "" {
			if srcImp := importsByPkgPath[pkgPath]; srcImp != "" {
				impPath = srcImp
			}
			if pkgPath == mp.PkgPath {
				return ""
			}
		}
		if localName, ok := localNames[impPath]; ok && impPath != "" {
			return localName
		}
		if pkgName != "" {
			return string(pkgName)
		}
		idx := strings.LastIndexByte(string(impPath), '/')
		return string(impPath[idx+1:])
	}
}

// importInfo collects information about the import specified by imp,
// extracting its file-local name, package name, import path, and package path.
//
// If metadata is missing for the import, the resulting package name and
// package path may be empty, and the file local name may be guessed based on
// the import path.
//
// Note: previous versions of this helper used a PackageID->PackagePath map
// extracted from m, for extracting package path even in the case where
// metadata for a dep was missing. This should not be necessary, as we should
// always have metadata for IDs contained in DepsByPkgPath.
func importInfo(s metadata.Source, imp *ast.ImportSpec, mp *metadata.Package) (string, PackageName, ImportPath, PackagePath) {
	var (
		name    string // local name
		pkgName PackageName
		impPath = metadata.UnquoteImportPath(imp)
		pkgPath PackagePath
	)

	// If the import has a local name, use it.
	if imp.Name != nil {
		name = imp.Name.Name
	}

	// Try to find metadata for the import. If successful and there is no local
	// name, the package name is the local name.
	if depID := mp.DepsByImpPath[impPath]; depID != "" {
		if depMP := s.Metadata(depID); depMP != nil {
			if name == "" {
				name = string(depMP.Name)
			}
			pkgName = depMP.Name
			pkgPath = depMP.PkgPath
		}
	}

	// If the local name is still unknown, guess it based on the import path.
	if name == "" {
		idx := strings.LastIndexByte(string(impPath), '/')
		name = string(impPath[idx+1:])
	}
	return name, pkgName, impPath, pkgPath
}

// isDirective reports whether c is a comment directive.
//
// Copied and adapted from go/src/go/ast/ast.go.
func isDirective(c string) bool {
	if len(c) < 3 {
		return false
	}
	if c[1] != '/' {
		return false
	}
	//-style comment (no newline at the end)
	c = c[2:]
	if len(c) == 0 {
		// empty line
		return false
	}
	// "//line " is a line directive.
	// (The // has been removed.)
	if strings.HasPrefix(c, "line ") {
		return true
	}

	// "//[a-z0-9]+:[a-z0-9]"
	// (The // has been removed.)
	colon := strings.Index(c, ":")
	if colon <= 0 || colon+1 >= len(c) {
		return false
	}
	for i := 0; i <= colon+1; i++ {
		if i == colon {
			continue
		}
		b := c[i]
		if !('a' <= b && b <= 'z' || '0' <= b && b <= '9') {
			return false
		}
	}
	return true
}

// embeddedIdent returns the type name identifier for an embedding x, if x in a
// valid embedding. Otherwise, it returns nil.
//
// Spec: An embedded field must be specified as a type name T or as a pointer
// to a non-interface type name *T
func embeddedIdent(x ast.Expr) *ast.Ident {
	if star, ok := x.(*ast.StarExpr); ok {
		x = star.X
	}
	switch ix := x.(type) { // check for instantiated receivers
	case *ast.IndexExpr:
		x = ix.X
	case *ast.IndexListExpr:
		x = ix.X
	}
	switch x := x.(type) {
	case *ast.Ident:
		return x
	case *ast.SelectorExpr:
		if _, ok := x.X.(*ast.Ident); ok {
			return x.Sel
		}
	}
	return nil
}

// An importFunc is an implementation of the single-method
// types.Importer interface based on a function value.
type ImporterFunc func(path string) (*types.Package, error)

func (f ImporterFunc) Import(path string) (*types.Package, error) { return f(path) }

// isBuiltin reports whether obj is a built-in symbol (e.g. append, iota, error.Error, unsafe.Slice).
// All other symbols have a valid position and a valid package.
func isBuiltin(obj types.Object) bool { return !obj.Pos().IsValid() }

// btoi returns int(b) as proposed in #64825.
func btoi(b bool) int {
	if b {
		return 1
	} else {
		return 0
	}
}

// boolCompare is a comparison function for booleans, returning -1 if x < y, 0
// if x == y, and 1 if x > y, where false < true.
func boolCompare(x, y bool) int {
	return btoi(x) - btoi(y)
}

// AbbreviateVarName returns an abbreviated var name based on the given full
// name (which may be a type name, for example).
//
// See the simple heuristics documented in line.
func AbbreviateVarName(s string) string {
	var (
		b            strings.Builder
		useNextUpper bool
	)
	for i, r := range s {
		// Stop if we encounter a non-identifier rune.
		if !unicode.IsLetter(r) && !unicode.IsNumber(r) {
			break
		}

		// Otherwise, take the first letter from word boundaries, assuming
		// camelCase.
		if i == 0 {
			b.WriteRune(unicode.ToLower(r))
		}

		if unicode.IsUpper(r) {
			if useNextUpper {
				b.WriteRune(unicode.ToLower(r))
				useNextUpper = false
			}
		} else {
			useNextUpper = true
		}
	}
	return b.String()
}

// CopyrightComment returns the copyright comment group from the input file, or
// nil if not found.
func CopyrightComment(file *ast.File) *ast.CommentGroup {
	if len(file.Comments) == 0 {
		return nil
	}

	// Copyright should appear before package decl and must be the first
	// comment group.
	if c := file.Comments[0]; c.Pos() < file.Package && c != file.Doc &&
		!isDirective(c.List[0].Text) &&
		strings.Contains(strings.ToLower(c.List[0].Text), "copyright") {
		return c
	}

	return nil
}

var buildConstraintRe = regexp.MustCompile(`^//(go:build|\s*\+build).*`)

// buildConstraintComment returns the build constraint comment from the input
// file.
// Returns nil if not found.
func buildConstraintComment(file *ast.File) *ast.Comment {
	for _, cg := range file.Comments {
		// In Go files a build constraint must appear before the package clause.
		// See https://pkg.go.dev/cmd/go#hdr-Build_constraints
		if cg.Pos() > file.Package {
			return nil
		}

		for _, c := range cg.List {
			// TODO: use ast.ParseDirective when available (#68021).
			if buildConstraintRe.MatchString(c.Text) {
				return c
			}
		}
	}

	return nil
}


================================================
FILE: gopls/internal/golang/workspace_symbol.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"cmp"
	"context"
	"fmt"
	"path/filepath"
	"runtime"
	"slices"
	"sort"
	"strings"
	"unicode"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/symbols"
	"golang.org/x/tools/gopls/internal/fuzzy"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
)

// maxSymbols defines the maximum number of symbol results that should ever be
// sent in response to a client.
const maxSymbols = 100

// WorkspaceSymbols matches symbols across all views using the given query,
// according to the match semantics parameterized by matcherType and style.
//
// The workspace symbol method is defined in the spec as follows:
//
//	The workspace symbol request is sent from the client to the server to
//	list project-wide symbols matching the query string.
//
// It is unclear what "project-wide" means here, but given the parameters of
// workspace/symbol do not include any workspace identifier, then it has to be
// assumed that "project-wide" means "across all workspaces".  Hence why
// WorkspaceSymbols receives the views []View.
//
// However, it then becomes unclear what it would mean to call WorkspaceSymbols
// with a different configured SymbolMatcher per View. Therefore we assume that
// Session level configuration will define the SymbolMatcher to be used for the
// WorkspaceSymbols method.
func WorkspaceSymbols(ctx context.Context, matcher settings.SymbolMatcher, style settings.SymbolStyle, snapshots []*cache.Snapshot, query string) ([]protocol.SymbolInformation, error) {
	ctx, done := event.Start(ctx, "golang.WorkspaceSymbols")
	defer done()
	if query == "" {
		return nil, nil
	}

	var s symbolizer
	switch style {
	case settings.DynamicSymbols:
		s = dynamicSymbolMatch
	case settings.FullyQualifiedSymbols:
		s = fullyQualifiedSymbolMatch
	case settings.PackageQualifiedSymbols:
		s = packageSymbolMatch
	default:
		panic(fmt.Errorf("unknown symbol style: %v", style))
	}

	return collectSymbols(ctx, snapshots, matcher, s, query)
}

// A matcherFunc returns the index and score of a symbol match.
//
// See the comment for symbolCollector for more information.
type matcherFunc func(chunks []string) (int, float64)

// A symbolizer returns the best symbol match for a name with pkg, according to
// some heuristic. The symbol name is passed as the slice nameParts of logical
// name pieces. For example, for myType.field the caller can pass either
// []string{"myType.field"} or []string{"myType.", "field"}.
//
// See the comment for symbolCollector for more information.
//
// The space argument is an empty slice with spare capacity that may be used
// to allocate the result.
type symbolizer func(space []string, name string, pkg *metadata.Package, m matcherFunc) ([]string, float64)

func fullyQualifiedSymbolMatch(space []string, name string, pkg *metadata.Package, matcher matcherFunc) ([]string, float64) {
	if _, score := dynamicSymbolMatch(space, name, pkg, matcher); score > 0 {
		return append(space, string(pkg.PkgPath), ".", name), score
	}
	return nil, 0
}

func dynamicSymbolMatch(space []string, name string, pkg *metadata.Package, matcher matcherFunc) ([]string, float64) {
	if metadata.IsCommandLineArguments(pkg.ID) {
		// command-line-arguments packages have a non-sensical package path, so
		// just use their package name.
		return packageSymbolMatch(space, name, pkg, matcher)
	}

	var score float64

	endsInPkgName := strings.HasSuffix(string(pkg.PkgPath), string(pkg.Name))

	// If the package path does not end in the package name, we need to check the
	// package-qualified symbol as an extra pass first.
	if !endsInPkgName {
		pkgQualified := append(space, string(pkg.Name), ".", name)
		idx, score := matcher(pkgQualified)
		nameStart := len(pkg.Name) + 1
		if score > 0 {
			// If our match is contained entirely within the unqualified portion,
			// just return that.
			if idx >= nameStart {
				return append(space, name), score
			}
			// Lower the score for matches that include the package name.
			return pkgQualified, score * 0.8
		}
	}

	// Now try matching the fully qualified symbol.
	fullyQualified := append(space, string(pkg.PkgPath), ".", name)
	idx, score := matcher(fullyQualified)

	// As above, check if we matched just the unqualified symbol name.
	nameStart := len(pkg.PkgPath) + 1
	if idx >= nameStart {
		return append(space, name), score
	}

	// If our package path ends in the package name, we'll have skipped the
	// initial pass above, so check if we matched just the package-qualified
	// name.
	if endsInPkgName && idx >= 0 {
		pkgStart := len(pkg.PkgPath) - len(pkg.Name)
		if idx >= pkgStart {
			return append(space, string(pkg.Name), ".", name), score
		}
	}

	// Our match was not contained within the unqualified or package qualified
	// symbol. Return the fully qualified symbol but discount the score.
	return fullyQualified, score * 0.6
}

func packageSymbolMatch(space []string, name string, pkg *metadata.Package, matcher matcherFunc) ([]string, float64) {
	qualified := append(space, string(pkg.Name), ".", name)
	if _, s := matcher(qualified); s > 0 {
		return qualified, s
	}
	return nil, 0
}

func buildMatcher(matcher settings.SymbolMatcher, query string) matcherFunc {
	switch matcher {
	case settings.SymbolFuzzy:
		return parseQuery(query, newFuzzyMatcher)
	case settings.SymbolFastFuzzy:
		return parseQuery(query, func(query string) matcherFunc {
			return fuzzy.NewSymbolMatcher(query).Match
		})
	case settings.SymbolCaseSensitive:
		return matchExact(query)
	case settings.SymbolCaseInsensitive:
		q := strings.ToLower(query)
		exact := matchExact(q)
		wrapper := []string{""}
		return func(chunks []string) (int, float64) {
			s := strings.Join(chunks, "")
			wrapper[0] = strings.ToLower(s)
			return exact(wrapper)
		}
	}
	panic(fmt.Errorf("unknown symbol matcher: %v", matcher))
}

func newFuzzyMatcher(query string) matcherFunc {
	fm := fuzzy.NewMatcher(query)
	return func(chunks []string) (int, float64) {
		score := float64(fm.ScoreChunks(chunks))
		ranges := fm.MatchedRanges()
		if len(ranges) > 0 {
			return ranges[0], score
		}
		return -1, score
	}
}

// parseQuery parses a field-separated symbol query, extracting the special
// characters listed below, and returns a matcherFunc corresponding to the AND
// of all field queries.
//
// Special characters:
//
//	^  match exact prefix
//	$  match exact suffix
//	'  match exact
//
// In all three of these special queries, matches are 'smart-cased', meaning
// they are case sensitive if the symbol query contains any upper-case
// characters, and case insensitive otherwise.
func parseQuery(q string, newMatcher func(string) matcherFunc) matcherFunc {
	fields := strings.Fields(q)
	if len(fields) == 0 {
		return func([]string) (int, float64) { return -1, 0 }
	}
	var funcs []matcherFunc
	for _, field := range fields {
		var f matcherFunc
		switch {
		case strings.HasPrefix(field, "^"):
			prefix := field[1:]
			f = smartCase(prefix, func(chunks []string) (int, float64) {
				s := strings.Join(chunks, "")
				if strings.HasPrefix(s, prefix) {
					return 0, 1
				}
				return -1, 0
			})
		case strings.HasPrefix(field, "'"):
			exact := field[1:]
			f = smartCase(exact, matchExact(exact))
		case strings.HasSuffix(field, "$"):
			suffix := field[0 : len(field)-1]
			f = smartCase(suffix, func(chunks []string) (int, float64) {
				s := strings.Join(chunks, "")
				if strings.HasSuffix(s, suffix) {
					return len(s) - len(suffix), 1
				}
				return -1, 0
			})
		default:
			f = newMatcher(field)
		}
		funcs = append(funcs, f)
	}
	if len(funcs) == 1 {
		return funcs[0]
	}
	return comboMatcher(funcs).match
}

func matchExact(exact string) matcherFunc {
	return func(chunks []string) (int, float64) {
		s := strings.Join(chunks, "")
		if idx := strings.LastIndex(s, exact); idx >= 0 {
			return idx, 1
		}
		return -1, 0
	}
}

// smartCase returns a matcherFunc that is case-sensitive if q contains any
// upper-case characters, and case-insensitive otherwise.
func smartCase(q string, m matcherFunc) matcherFunc {
	insensitive := strings.ToLower(q) == q
	wrapper := []string{""}
	return func(chunks []string) (int, float64) {
		s := strings.Join(chunks, "")
		if insensitive {
			s = strings.ToLower(s)
		}
		wrapper[0] = s
		return m(wrapper)
	}
}

type comboMatcher []matcherFunc

func (c comboMatcher) match(chunks []string) (int, float64) {
	score := 1.0
	first := 0
	for _, f := range c {
		idx, s := f(chunks)
		if idx < first {
			first = idx
		}
		score *= s
	}
	return first, score
}

// collectSymbols calls snapshot.Symbols to walk the syntax trees of
// all files in the views' current snapshots, and returns a sorted,
// scored list of symbols that best match the parameters.
//
// How it matches symbols is parameterized by two interfaces:
//   - A matcherFunc determines how well a string symbol matches a query. It
//     returns a non-negative score indicating the quality of the match. A score
//     of zero indicates no match.
//   - A symbolizer determines how we extract the symbol for an object. This
//     enables the 'symbolStyle' configuration option.
func collectSymbols(ctx context.Context, snapshots []*cache.Snapshot, matcherType settings.SymbolMatcher, symbolizer symbolizer, query string) ([]protocol.SymbolInformation, error) {
	// Extract symbols from all files.
	var work []symbolFile
	seen := make(map[protocol.DocumentURI]*metadata.Package) // only scan each file once

	for _, snapshot := range snapshots {
		// Use the root view URIs for determining (lexically)
		// whether a URI is in any open workspace.
		folderURI := snapshot.Folder()

		pathIncluded := cache.PathIncludeFunc(snapshot.Options().DirectoryFilters)
		folder := filepath.ToSlash(folderURI.Path())

		var (
			mps []*metadata.Package
			err error
		)
		if snapshot.Options().SymbolScope == settings.AllSymbolScope {
			mps, err = snapshot.AllMetadata(ctx)
		} else {
			mps, err = snapshot.WorkspaceMetadata(ctx)
		}
		if err != nil {
			return nil, err
		}
		metadata.RemoveIntermediateTestVariants(&mps)

		// We'll process packages in order to consider candidate symbols.
		//
		// The order here doesn't matter for correctness, but can affect
		// performance:
		//  - As workspace packages score higher than non-workspace packages,
		//    sort them first to increase the likelihood that non-workspace
		//    symbols are skipped.
		//  - As files can be contained in multiple packages, sort by wider
		//    packages first, to cover all files with fewer packages.
		workspacePackages := snapshot.WorkspacePackages()
		slices.SortFunc(mps, func(a, b *metadata.Package) int {
			_, aworkspace := workspacePackages.Value(a.ID)
			_, bworkspace := workspacePackages.Value(b.ID)
			if cmp := boolCompare(aworkspace, bworkspace); cmp != 0 {
				return -cmp // workspace packages first
			}
			return -cmp.Compare(len(a.CompiledGoFiles), len(b.CompiledGoFiles)) // widest first
		})

		// Filter out unneeded mps in place, and collect file<->package
		// associations.
		var ids []metadata.PackageID
		for _, mp := range mps {
			used := false
			for _, list := range [][]protocol.DocumentURI{mp.GoFiles, mp.CompiledGoFiles} {
				for _, uri := range list {
					if _, ok := seen[uri]; !ok {
						seen[uri] = mp
						used = true
					}
				}
			}
			if used {
				mps[len(ids)] = mp
				ids = append(ids, mp.ID)
			}
		}
		mps = mps[:len(ids)]

		symbolPkgs, err := snapshot.Symbols(ctx, ids...)
		if err != nil {
			return nil, err
		}

		for i, sp := range symbolPkgs {
			if sp == nil {
				continue
			}
			mp := mps[i]
			for i, syms := range sp.Symbols {
				uri := sp.Files[i]
				norm := filepath.ToSlash(uri.Path())
				nm := strings.TrimPrefix(norm, folder)
				if !pathIncluded(nm) {
					continue
				}
				// Only scan each file once.
				if seen[uri] != mp {
					continue
				}
				// seen[uri] = true
				_, workspace := workspacePackages.Value(mp.ID)
				work = append(work, symbolFile{mp, uri, syms, workspace})
			}
		}
	}

	// Match symbols in parallel.
	// Each worker has its own symbolStore,
	// which we merge at the end.
	nmatchers := runtime.GOMAXPROCS(-1) // matching is CPU bound
	results := make(chan *symbolStore)
	for i := range nmatchers {
		go func(i int) {
			matcher := buildMatcher(matcherType, query)
			store := new(symbolStore)
			// Assign files to workers in round-robin fashion.
			for j := i; j < len(work); j += nmatchers {
				matchFile(store, symbolizer, matcher, work[j])
			}
			results <- store
		}(i)
	}

	// Gather and merge results as they arrive.
	var unified symbolStore
	for range nmatchers {
		store := <-results
		for _, syms := range store.res {
			if syms != nil {
				unified.store(syms)
			}
		}
	}
	return unified.results(), nil
}

// symbolFile holds symbol information for a single file.
type symbolFile struct {
	mp        *metadata.Package
	uri       protocol.DocumentURI
	syms      []symbols.Symbol
	workspace bool
}

// matchFile scans a symbol file and adds matching symbols to the store.
func matchFile(store *symbolStore, symbolizer symbolizer, matcher matcherFunc, f symbolFile) {
	space := make([]string, 0, 3)
	for _, sym := range f.syms {
		symbolParts, score := symbolizer(space, sym.Name, f.mp, matcher)

		// Check if the score is too low before applying any downranking.
		if store.tooLow(score) {
			continue
		}

		// Factors to apply to the match score for the purpose of downranking
		// results.
		//
		// These numbers were crudely calibrated based on trial-and-error using a
		// small number of sample queries. Adjust as necessary.
		//
		// All factors are multiplicative, meaning if more than one applies they are
		// multiplied together.
		const (
			// nonWorkspaceFactor is applied to symbols outside the workspace.
			// Developers are less likely to want to jump to code that they
			// are not actively working on.
			nonWorkspaceFactor = 0.5
			// nonWorkspaceUnexportedFactor is applied to unexported symbols outside
			// the workspace. Since one wouldn't usually jump to unexported
			// symbols to understand a package API, they are particularly irrelevant.
			nonWorkspaceUnexportedFactor = 0.5
			// every field or method nesting level to access the field decreases
			// the score by a factor of 1.0 - depth*depthFactor, up to a depth of
			// 3.
			//
			// Use a small constant here, as this exists mostly to break ties
			// (e.g. given a type Foo and a field x.Foo, prefer Foo).
			depthFactor = 0.01
		)

		// TODO(rfindley): compute this downranking *before* calling the symbolizer
		// (which is expensive), so that we can pre-filter candidates whose score
		// will always be too low, even with a perfect match.

		startWord := true
		exported := true
		depth := 0.0
		for _, r := range sym.Name {
			if startWord && !unicode.IsUpper(r) {
				exported = false
			}
			if r == '.' {
				startWord = true
				depth++
			} else {
				startWord = false
			}
		}

		// Apply downranking based on workspace position.
		if !f.workspace {
			score *= nonWorkspaceFactor
			if !exported {
				score *= nonWorkspaceUnexportedFactor
			}
		}

		// Apply downranking based on symbol depth.
		if depth > 3 {
			depth = 3
		}
		score *= 1.0 - depth*depthFactor

		if store.tooLow(score) {
			continue
		}

		si := &scoredSymbol{
			score: score,
			info: protocol.SymbolInformation{
				Name:          strings.Join(symbolParts, ""),
				Kind:          sym.Kind,
				Location:      f.uri.Location(sym.Range),
				ContainerName: string(f.mp.PkgPath),
			},
		}
		store.store(si)
	}
}

type symbolStore struct {
	res [maxSymbols]*scoredSymbol
}

// store inserts si into the sorted results, if si has a high enough score.
func (sc *symbolStore) store(ss *scoredSymbol) {
	if sc.tooLow(ss.score) {
		return
	}
	insertAt := sort.Search(len(sc.res), func(i int) bool {
		if sc.res[i] == nil {
			return true
		}
		// Sort by score, then symbol length, and finally lexically.
		if ss.score != sc.res[i].score {
			return ss.score > sc.res[i].score
		}
		if cmp := cmp.Compare(len(ss.info.Name), len(sc.res[i].info.Name)); cmp != 0 {
			return cmp < 0 // shortest first
		}
		return ss.info.Name < sc.res[i].info.Name
	})
	if insertAt < len(sc.res)-1 {
		copy(sc.res[insertAt+1:], sc.res[insertAt:len(sc.res)-1])
	}
	sc.res[insertAt] = ss
}

func (sc *symbolStore) tooLow(score float64) bool {
	last := sc.res[len(sc.res)-1]
	if last == nil {
		return false
	}
	return score <= last.score
}

func (sc *symbolStore) results() []protocol.SymbolInformation {
	var res []protocol.SymbolInformation
	for _, si := range sc.res {
		if si == nil || si.score <= 0 {
			return res
		}
		res = append(res, si.info)
	}
	return res
}

type scoredSymbol struct {
	score float64
	info  protocol.SymbolInformation
}


================================================
FILE: gopls/internal/golang/workspace_symbol_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package golang

import (
	"testing"

	"golang.org/x/tools/gopls/internal/cache"
)

func TestParseQuery(t *testing.T) {
	tests := []struct {
		query, s  string
		wantMatch bool
	}{
		{"", "anything", false},
		{"any", "anything", true},
		{"any$", "anything", false},
		{"ing$", "anything", true},
		{"ing$", "anythinG", true},
		{"inG$", "anything", false},
		{"^any", "anything", true},
		{"^any", "Anything", true},
		{"^Any", "anything", false},
		{"at", "anything", true},
		// TODO: this appears to be a bug in the fuzzy matching algorithm. 'At'
		// should cause a case-sensitive match.
		// {"At", "anything", false},
		{"At", "Anything", true},
		{"'yth", "Anything", true},
		{"'yti", "Anything", false},
		{"'any 'thing", "Anything", true},
		{"anythn nythg", "Anything", true},
		{"ntx", "Anything", false},
		{"anythn", "anything", true},
		{"ing", "anything", true},
		{"anythn nythgx", "anything", false},
	}

	for _, test := range tests {
		matcher := parseQuery(test.query, newFuzzyMatcher)
		if _, score := matcher([]string{test.s}); score > 0 != test.wantMatch {
			t.Errorf("parseQuery(%q) match for %q: %.2g, want match: %t", test.query, test.s, score, test.wantMatch)
		}
	}
}

func TestPathIncludeFunc(t *testing.T) {
	tests := []struct {
		filters  []string
		included []string
		excluded []string
	}{
		{
			[]string{"+**/c.go"},
			[]string{"a/c.go", "a/b/c.go"},
			[]string{},
		},
		{
			[]string{"+a/**/c.go"},
			[]string{"a/b/c.go", "a/b/d/c.go", "a/c.go"},
			[]string{},
		},
		{
			[]string{"-a/c.go", "+a/**"},
			[]string{"a/c.go"},
			[]string{},
		},
		{
			[]string{"+a/**/c.go", "-**/c.go"},
			[]string{},
			[]string{"a/b/c.go"},
		},
		{
			[]string{"+a/**/c.go", "-a/**"},
			[]string{},
			[]string{"a/b/c.go"},
		},
		{
			[]string{"+**/c.go", "-a/**/c.go"},
			[]string{},
			[]string{"a/b/c.go"},
		},
		{
			[]string{"+foobar", "-foo"},
			[]string{"foobar", "foobar/a"},
			[]string{"foo", "foo/a"},
		},
		{
			[]string{"+", "-"},
			[]string{},
			[]string{"foobar", "foobar/a", "foo", "foo/a"},
		},
		{
			[]string{"-", "+"},
			[]string{"foobar", "foobar/a", "foo", "foo/a"},
			[]string{},
		},
		{
			[]string{"-a/**/b/**/c.go"},
			[]string{},
			[]string{"a/x/y/z/b/f/g/h/c.go"},
		},
		// tests for unsupported glob operators
		{
			[]string{"+**/c.go", "-a/*/c.go"},
			[]string{"a/b/c.go"},
			[]string{},
		},
		{
			[]string{"+**/c.go", "-a/?/c.go"},
			[]string{"a/b/c.go"},
			[]string{},
		},
		{
			[]string{"-b"}, // should only filter paths prefixed with the "b" directory
			[]string{"a/b/c.go", "bb"},
			[]string{"b/c/d.go", "b"},
		},
		// golang/vscode-go#3692
		{
			[]string{"-**/foo", "+**/bar"},
			[]string{"bar/a.go", "a/bar/b.go"},
			[]string{"foo/a.go", "a/foo/b.go"},
		},
	}

	for _, test := range tests {
		pathIncluded := cache.PathIncludeFunc(test.filters)
		for _, inc := range test.included {
			if !pathIncluded(inc) {
				t.Errorf("Filters %v excluded %v, wanted included", test.filters, inc)
			}
		}

		for _, exc := range test.excluded {
			if pathIncluded(exc) {
				t.Errorf("Filters %v included %v, wanted excluded", test.filters, exc)
			}
		}
	}
}


================================================
FILE: gopls/internal/label/keys.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package label provides common labels used to annotate gopls log messages
// and events.
package label

import "golang.org/x/tools/internal/event/keys"

var (
	File      = keys.NewString("file", "")
	Directory = keys.New("directory", "")
	URI       = keys.New("URI", "")
	Package   = keys.NewString("package", "") // sorted comma-separated list of Package IDs
	Query     = keys.New("query", "")
	ViewID    = keys.NewString("view_id", "")
	Snapshot  = keys.NewUint("snapshot", "")
	Operation = keys.NewString("operation", "")
	Duration  = keys.New("duration", "Elapsed time")

	Position     = keys.New("position", "")
	PackageCount = keys.NewInt("packages", "")
	Files        = keys.New("files", "")
	Port         = keys.NewInt("port", "")

	NewServer = keys.NewString("new_server", "A new server was added")
	EndServer = keys.NewString("end_server", "A server was shut down")

	ServerID     = keys.NewString("server", "The server ID an event is related to")
	Logfile      = keys.NewString("logfile", "")
	DebugAddress = keys.NewString("debug_address", "")
	GoplsPath    = keys.NewString("gopls_path", "")
	ClientID     = keys.NewString("client_id", "")

	Level = keys.NewInt("level", "The logging level")
)


================================================
FILE: gopls/internal/licenses/gen-licenses.sh
================================================
#!/bin/bash -eu

# Copyright 2020 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

set -o pipefail

output=$1
tempfile=$(mktemp)
cd $(dirname $0)

cat > $tempfile <<END
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate ./gen-licenses.sh licenses.go
package licenses

const Text = \`
END

# List all the modules gopls depends on, except other golang.org modules, which
# are known to have the same license.
mods=$(go list -deps -f '{{with .Module}}{{.Path}}{{end}}' golang.org/x/tools/gopls | sort -u | grep -v golang.org)
for mod in $mods; do
  # Find the license file, either LICENSE, COPYING, or LICENSE.md and add it to the result.
  dir=$(go list -m -f {{.Dir}} $mod)
  license=$(ls -1 $dir | grep -E -i '^(LICENSE|LICENSE.md|COPYING)?$')
  echo "-- $mod $license --" >> $tempfile
  echo >> $tempfile
  sed 's/^-- / &/' $dir/$license >> $tempfile
  echo >> $tempfile
done

echo "\`" >> $tempfile
mv $tempfile $output


================================================
FILE: gopls/internal/licenses/licenses.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate ./gen-licenses.sh licenses.go
package licenses

const Text = `
-- github.com/BurntSushi/toml COPYING --

The MIT License (MIT)

Copyright (c) 2013 TOML authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

-- github.com/fatih/camelcase LICENSE.md --

The MIT License (MIT)

Copyright (c) 2015 Fatih Arslan

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-- github.com/fatih/gomodifytags LICENSE --

Copyright (c) 2017, Fatih Arslan
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name of gomodifytags nor the names of its
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- github.com/fatih/structtag LICENSE --

Copyright (c) 2017, Fatih Arslan
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

* Redistributions in binary form must reproduce the above copyright notice,
  this list of conditions and the following disclaimer in the documentation
  and/or other materials provided with the distribution.

* Neither the name of structtag nor the names of its
  contributors may be used to endorse or promote products derived from
  this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

This software includes some portions from Go. Go is used under the terms of the
BSD like license.

Copyright (c) 2012 The Go Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

The Go gopher was designed by Renee French. http://reneefrench.blogspot.com/ The design is licensed under the Creative Commons 3.0 Attributions license. Read this article for more details: https://blog.golang.org/gopher

-- github.com/fsnotify/fsnotify LICENSE --

Copyright © 2012 The Go Authors. All rights reserved.
Copyright © fsnotify Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice, this
  list of conditions and the following disclaimer in the documentation and/or
  other materials provided with the distribution.
* Neither the name of Google Inc. nor the names of its contributors may be used
  to endorse or promote products derived from this software without specific
  prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- github.com/google/go-cmp LICENSE --

Copyright (c) 2017 The Go Authors. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of Google Inc. nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- github.com/google/jsonschema-go LICENSE --

MIT License

Copyright (c) 2025 JSON Schema Go Project Authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

-- github.com/modelcontextprotocol/go-sdk LICENSE --

The MCP project is undergoing a licensing transition from the MIT License to the Apache License, Version 2.0 ("Apache-2.0"). All new code and specification contributions to the project are licensed under Apache-2.0. Documentation contributions (excluding specifications) are licensed under CC-BY-4.0.

Contributions for which relicensing consent has been obtained are licensed under Apache-2.0. Contributions made by authors who originally licensed their work under the MIT License and who have not yet granted explicit permission to relicense remain licensed under the MIT License.

No rights beyond those granted by the applicable original license are conveyed for such contributions.

---

                                 Apache License
                           Version 2.0, January 2004
                        http://www.apache.org/licenses/

   TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION

   1. Definitions.

      "License" shall mean the terms and conditions for use, reproduction,
      and distribution as defined by Sections 1 through 9 of this document.

      "Licensor" shall mean the copyright owner or entity authorized by
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   2. Grant of Copyright License. Subject to the terms and conditions of
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   8. Limitation of Liability. In no event and under no legal theory,
      whether in tort (including negligence), contract, or otherwise,
      unless required by applicable law (such as deliberate and grossly
      negligent acts) or agreed to in writing, shall any Contributor be
      liable to You for damages, including any direct, indirect, special,
      incidental, or consequential damages of any character arising as a
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      Work (including but not limited to damages for loss of goodwill,
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      defend, and hold each Contributor harmless for any liability
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   END OF TERMS AND CONDITIONS

---

MIT License

Copyright (c) 2024-2025 Model Context Protocol a Series of LF Projects, LLC.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

---

Creative Commons Attribution 4.0 International (CC-BY-4.0)

Documentation in this project (excluding specifications) is licensed under
CC-BY-4.0. See https://creativecommons.org/licenses/by/4.0/legalcode for
the full license text.

-- github.com/segmentio/asm LICENSE --

MIT No Attribution

Copyright 2023 Segment

Permission is hereby granted, free of charge, to any person obtaining a copy of this
software and associated documentation files (the "Software"), to deal in the Software
without restriction, including without limitation the rights to use, copy, modify,
merge, publish, distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-- github.com/segmentio/encoding LICENSE --

MIT License

Copyright (c) 2019 Segment.io, Inc.

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.

-- github.com/yosida95/uritemplate/v3 LICENSE --

Copyright (C) 2016, Kohei YOSHIDA <https://yosida95.com/>. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

    * Redistributions of source code must retain the above copyright
      notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright
      notice, this list of conditions and the following disclaimer in the
      documentation and/or other materials provided with the distribution.
    * Neither the name of the copyright holder nor the names of its
      contributors may be used to endorse or promote products derived from
      this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- honnef.co/go/tools LICENSE --

Copyright (c) 2016 Dominik Honnef

Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
"Software"), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:

The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

-- mvdan.cc/gofumpt LICENSE --

Copyright (c) 2019, Daniel Martí. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of the copyright holder nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

-- mvdan.cc/xurls/v2 LICENSE --

Copyright (c) 2015, Daniel Martí. All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are
met:

   * Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
   * Redistributions in binary form must reproduce the above
copyright notice, this list of conditions and the following disclaimer
in the documentation and/or other materials provided with the
distribution.
   * Neither the name of the copyright holder nor the names of its
contributors may be used to endorse or promote products derived from
this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

`


================================================
FILE: gopls/internal/licenses/licenses_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package licenses_test

import (
	"bytes"
	"os"
	"os/exec"
	"runtime"
	"testing"
)

func TestLicenses(t *testing.T) {
	if runtime.GOOS != "linux" && runtime.GOOS != "darwin" {
		t.Skip("generating licenses only works on Unixes")
	}
	tmp, err := os.CreateTemp("", "")
	if err != nil {
		t.Fatal(err)
	}
	tmp.Close() // ignore error

	if out, err := exec.Command("./gen-licenses.sh", tmp.Name()).CombinedOutput(); err != nil {
		t.Fatalf("generating licenses failed: %q, %v", out, err)
	}

	got, err := os.ReadFile(tmp.Name())
	if err != nil {
		t.Fatal(err)
	}
	want, err := os.ReadFile("licenses.go")
	if err != nil {
		t.Fatal(err)
	}
	if !bytes.Equal(got, want) {
		t.Error("combined license text needs updating. Run: `go generate ./internal/licenses` from the gopls module.")
	}
}


================================================
FILE: gopls/internal/lsprpc/autostart_default.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

import (
	"fmt"
	"os/exec"
)

var (
	daemonize             = func(*exec.Cmd) {}
	autoNetworkAddress    = autoNetworkAddressDefault
	verifyRemoteOwnership = verifyRemoteOwnershipDefault
)

func runRemote(cmd *exec.Cmd) error {
	daemonize(cmd)
	if err := cmd.Start(); err != nil {
		return fmt.Errorf("starting remote gopls: %w", err)
	}
	return nil
}

// autoNetworkAddressDefault returns the default network and address for the
// automatically-started gopls remote. See autostart_posix.go for more
// information.
func autoNetworkAddressDefault(goplsPath, id string) (network string, address string) {
	if id != "" {
		panic("identified remotes are not supported on windows")
	}
	return "tcp", "localhost:37374"
}

func verifyRemoteOwnershipDefault(network, address string) (bool, error) {
	return true, nil
}


================================================
FILE: gopls/internal/lsprpc/autostart_posix.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris

package lsprpc

import (
	"crypto/sha256"
	"errors"
	"fmt"
	"log"
	"os"
	"os/exec"
	"os/user"
	"path/filepath"
	"strconv"
	"syscall"
)

func init() {
	daemonize = daemonizePosix
	autoNetworkAddress = autoNetworkAddressPosix
	verifyRemoteOwnership = verifyRemoteOwnershipPosix
}

func daemonizePosix(cmd *exec.Cmd) {
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setsid: true,
	}
}

// autoNetworkAddressPosix resolves an id on the 'auto' pseudo-network to a
// real network and address. On unix, this uses unix domain sockets.
func autoNetworkAddressPosix(goplsPath, id string) (network string, address string) {
	// Especially when doing local development or testing, it's important that
	// the remote gopls instance we connect to is running the same binary as our
	// forwarder. So we encode a short hash of the binary path into the daemon
	// socket name. If possible, we also include the buildid in this hash, to
	// account for long-running processes where the binary has been subsequently
	// rebuilt.
	h := sha256.New()
	cmd := exec.Command("go", "tool", "buildid", goplsPath)
	cmd.Stdout = h
	var pathHash []byte
	if err := cmd.Run(); err == nil {
		pathHash = h.Sum(nil)
	} else {
		log.Printf("error getting current buildid: %v", err)
		sum := sha256.Sum256([]byte(goplsPath))
		pathHash = sum[:]
	}
	shortHash := fmt.Sprintf("%x", pathHash)[:6]
	user := os.Getenv("USER")
	if user == "" {
		user = "shared"
	}
	basename := filepath.Base(goplsPath)
	idComponent := ""
	if id != "" {
		idComponent = "-" + id
	}
	runtimeDir := os.TempDir()
	if xdg := os.Getenv("XDG_RUNTIME_DIR"); xdg != "" {
		runtimeDir = xdg
	}
	return "unix", filepath.Join(runtimeDir, fmt.Sprintf("%s-%s-daemon.%s%s", basename, shortHash, user, idComponent))
}

func verifyRemoteOwnershipPosix(network, address string) (bool, error) {
	if network != "unix" {
		return true, nil
	}
	fi, err := os.Stat(address)
	if err != nil {
		if os.IsNotExist(err) {
			return true, nil
		}
		return false, fmt.Errorf("checking socket owner: %w", err)
	}
	stat, ok := fi.Sys().(*syscall.Stat_t)
	if !ok {
		return false, errors.New("fi.Sys() is not a Stat_t")
	}
	user, err := user.Current()
	if err != nil {
		return false, fmt.Errorf("checking current user: %w", err)
	}
	uid, err := strconv.ParseUint(user.Uid, 10, 32)
	if err != nil {
		return false, fmt.Errorf("parsing current UID: %w", err)
	}
	return stat.Uid == uint32(uid), nil
}


================================================
FILE: gopls/internal/lsprpc/binder.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc


================================================
FILE: gopls/internal/lsprpc/binder_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc_test

import (
	"context"
	"regexp"
	"strings"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"

	. "golang.org/x/tools/gopls/internal/lsprpc"
)

// ServerBinder binds incoming connections to a new server.
type ServerBinder struct {
	newServer ServerFunc
}

func NewServerBinder(newServer ServerFunc) *ServerBinder {
	return &ServerBinder{newServer: newServer}
}

// streamServer used to have this method, but it was never used.
// TODO(adonovan): figure out whether we need any of this machinery
// and, if not, delete it. In the meantime, it's better that it sit
// in the test package with all the other mothballed machinery
// than in the production code where it would couple streamServer
// and ServerBinder.
/*
func (s *streamServer) Binder() *ServerBinder {
	newServer := func(ctx context.Context, client protocol.ClientCloser) protocol.Server {
		session := cache.NewSession(ctx, s.cache)
		svr := s.serverForTest
		if svr == nil {
			options := settings.DefaultOptions(s.optionsOverrides)
			svr = server.New(session, client, options)
			if instance := debug.GetInstance(ctx); instance != nil {
				instance.AddService(svr, session)
			}
		}
		return svr
	}
	return NewServerBinder(newServer)
}
*/

func (b *ServerBinder) Bind(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
	client := protocol.ClientDispatcherV2(conn)
	server := b.newServer(ctx, client)
	serverHandler := protocol.ServerHandlerV2(server)
	// Wrap the server handler to inject the client into each request context, so
	// that log events are reflected back to the client.
	wrapped := jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
		ctx = protocol.WithClient(ctx, client)
		return serverHandler.Handle(ctx, req)
	})
	preempter := &Canceler{
		Conn: conn,
	}
	return jsonrpc2_v2.ConnectionOptions{
		Handler:   wrapped,
		Preempter: preempter,
	}
}

type TestEnv struct {
	Conns   []*jsonrpc2_v2.Connection
	Servers []*jsonrpc2_v2.Server
}

func (e *TestEnv) Shutdown(t *testing.T) {
	for _, s := range e.Servers {
		s.Shutdown()
	}
	for _, c := range e.Conns {
		if err := c.Close(); err != nil {
			t.Error(err)
		}
	}
	for _, s := range e.Servers {
		if err := s.Wait(); err != nil {
			t.Error(err)
		}
	}
}

func (e *TestEnv) serve(ctx context.Context, t *testing.T, server jsonrpc2_v2.Binder) (jsonrpc2_v2.Listener, *jsonrpc2_v2.Server) {
	l, err := jsonrpc2_v2.NetPipeListener(ctx)
	if err != nil {
		t.Fatal(err)
	}
	s := jsonrpc2_v2.NewServer(ctx, l, server)
	e.Servers = append(e.Servers, s)
	return l, s
}

func (e *TestEnv) dial(ctx context.Context, t *testing.T, dialer jsonrpc2_v2.Dialer, client jsonrpc2_v2.Binder, forwarded bool) *jsonrpc2_v2.Connection {
	if forwarded {
		l, _ := e.serve(ctx, t, NewForwardBinder(dialer))
		dialer = l.Dialer()
	}
	conn, err := jsonrpc2_v2.Dial(ctx, dialer, client, nil)
	if err != nil {
		t.Fatal(err)
	}
	e.Conns = append(e.Conns, conn)
	return conn
}

func staticClientBinder(client protocol.Client) jsonrpc2_v2.Binder {
	f := func(context.Context, protocol.Server) protocol.Client { return client }
	return NewClientBinder(f)
}

func staticServerBinder(server protocol.Server) jsonrpc2_v2.Binder {
	f := func(ctx context.Context, client protocol.ClientCloser) protocol.Server {
		return server
	}
	return NewServerBinder(f)
}

func TestClientLoggingV2(t *testing.T) {
	ctx := context.Background()

	for name, forwarded := range map[string]bool{
		"forwarded":  true,
		"standalone": false,
	} {
		t.Run(name, func(t *testing.T) {
			client := FakeClient{Logs: make(chan string, 10)}
			env := new(TestEnv)
			defer env.Shutdown(t)
			l, _ := env.serve(ctx, t, staticServerBinder(PingServer{}))
			conn := env.dial(ctx, t, l.Dialer(), staticClientBinder(client), forwarded)

			if err := protocol.ServerDispatcherV2(conn).DidOpen(ctx, &protocol.DidOpenTextDocumentParams{}); err != nil {
				t.Errorf("DidOpen: %v", err)
			}
			select {
			case got := <-client.Logs:
				want := "ping"
				matched, err := regexp.MatchString(want, got)
				if err != nil {
					t.Fatal(err)
				}
				if !matched {
					t.Errorf("got log %q, want a log containing %q", got, want)
				}
			case <-time.After(1 * time.Second):
				t.Error("timeout waiting for client log")
			}
		})
	}
}

func TestRequestCancellationV2(t *testing.T) {
	ctx := context.Background()

	for name, forwarded := range map[string]bool{
		"forwarded":  true,
		"standalone": false,
	} {
		t.Run(name, func(t *testing.T) {
			server := WaitableServer{
				Started:   make(chan struct{}),
				Completed: make(chan error),
			}
			env := new(TestEnv)
			defer env.Shutdown(t)
			l, _ := env.serve(ctx, t, staticServerBinder(server))
			client := FakeClient{Logs: make(chan string, 10)}
			conn := env.dial(ctx, t, l.Dialer(), staticClientBinder(client), forwarded)

			sd := protocol.ServerDispatcherV2(conn)
			ctx, cancel := context.WithCancel(ctx)

			result := make(chan error)
			go func() {
				_, err := sd.Hover(ctx, &protocol.HoverParams{})
				result <- err
			}()
			// Wait for the Hover request to start.
			<-server.Started
			cancel()
			if err := <-result; err == nil {
				t.Error("nil error for cancelled Hover(), want non-nil")
			}
			if err := <-server.Completed; err == nil || !strings.Contains(err.Error(), "cancelled hover") {
				t.Errorf("Hover(): unexpected server-side error %v", err)
			}
		})
	}
}


================================================
FILE: gopls/internal/lsprpc/commandinterceptor_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc_test

import (
	"context"
	"encoding/json"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"

	. "golang.org/x/tools/gopls/internal/lsprpc"
)

func CommandInterceptor(command string, run func(*protocol.ExecuteCommandParams) (any, error)) Middleware {
	return BindHandler(func(delegate jsonrpc2_v2.Handler) jsonrpc2_v2.Handler {
		return jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
			if req.Method == "workspace/executeCommand" {
				var params protocol.ExecuteCommandParams
				if err := json.Unmarshal(req.Params, &params); err == nil {
					if params.Command == command {
						return run(&params)
					}
				}
			}

			return delegate.Handle(ctx, req)
		})
	})
}

func TestCommandInterceptor(t *testing.T) {
	const command = "foo"
	caught := false
	intercept := func(_ *protocol.ExecuteCommandParams) (any, error) {
		caught = true
		return map[string]any{}, nil
	}

	ctx := context.Background()
	env := new(TestEnv)
	defer env.Shutdown(t)
	mw := CommandInterceptor(command, intercept)
	l, _ := env.serve(ctx, t, mw(noopBinder))
	conn := env.dial(ctx, t, l.Dialer(), noopBinder, false)

	params := &protocol.ExecuteCommandParams{
		Command: command,
	}
	var res any
	err := conn.Call(ctx, "workspace/executeCommand", params).Await(ctx, &res)
	if err != nil {
		t.Fatal(err)
	}
	if !caught {
		t.Errorf("workspace/executeCommand was not intercepted")
	}
}


================================================
FILE: gopls/internal/lsprpc/dialer.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

import (
	"context"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"time"

	"golang.org/x/tools/internal/event"
)

// autoNetwork is the pseudo network type used to signal that gopls should use
// automatic discovery to resolve a remote address.
const autoNetwork = "auto"

// An autoDialer is a jsonrpc2 dialer that understands the 'auto' network.
type autoDialer struct {
	network, addr string // the 'real' network and address
	isAuto        bool   // whether the server is on the 'auto' network

	executable string
	argFunc    func(network, addr string) []string
}

func newAutoDialer(rawAddr string, argFunc func(network, addr string) []string) (*autoDialer, error) {
	d := autoDialer{
		argFunc: argFunc,
	}
	d.network, d.addr = ParseAddr(rawAddr)
	if d.network == autoNetwork {
		d.isAuto = true
		bin, err := os.Executable()
		if err != nil {
			return nil, fmt.Errorf("getting executable: %w", err)
		}
		d.executable = bin
		d.network, d.addr = autoNetworkAddress(bin, d.addr)
	}
	return &d, nil
}

// Dial implements the jsonrpc2.Dialer interface.
func (d *autoDialer) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
	conn, err := d.dialNet(ctx)
	return conn, err
}

// TODO(rFindley): remove this once we no longer need to integrate with v1 of
// the jsonrpc2 package.
func (d *autoDialer) dialNet(ctx context.Context) (net.Conn, error) {
	// Attempt to verify that we own the remote. This is imperfect, but if we can
	// determine that the remote is owned by a different user, we should fail.
	ok, err := verifyRemoteOwnership(d.network, d.addr)
	if err != nil {
		// If the ownership check itself failed, we fail open but log an error to
		// the user.
		event.Error(ctx, "unable to check daemon socket owner, failing open", err)
	} else if !ok {
		// We successfully checked that the socket is not owned by us, we fail
		// closed.
		return nil, fmt.Errorf("socket %q is owned by a different user", d.addr)
	}
	const dialTimeout = 1 * time.Second
	// Try dialing our remote once, in case it is already running.
	netConn, err := net.DialTimeout(d.network, d.addr, dialTimeout)
	if err == nil {
		return netConn, nil
	}
	if d.isAuto && d.argFunc != nil {
		if d.network == "unix" {
			// Sometimes the socketfile isn't properly cleaned up when the server
			// shuts down. Since we have already tried and failed to dial this
			// address, it should *usually* be safe to remove the socket before
			// binding to the address.
			// TODO(rfindley): there is probably a race here if multiple server
			// instances are simultaneously starting up.
			if _, err := os.Stat(d.addr); err == nil {
				if err := os.Remove(d.addr); err != nil {
					return nil, fmt.Errorf("removing remote socket file: %w", err)
				}
			}
		}
		args := d.argFunc(d.network, d.addr)
		cmd := exec.Command(d.executable, args...)
		if err := runRemote(cmd); err != nil {
			return nil, err
		}
	}

	const retries = 5
	// It can take some time for the newly started server to bind to our address,
	// so we retry for a bit.
	for retry := range retries {
		startDial := time.Now()
		netConn, err = net.DialTimeout(d.network, d.addr, dialTimeout)
		if err == nil {
			return netConn, nil
		}
		event.Log(ctx, fmt.Sprintf("failed attempt #%d to connect to remote: %v\n", retry+2, err))
		// In case our failure was a fast-failure, ensure we wait at least
		// f.dialTimeout before trying again.
		if retry != retries-1 {
			time.Sleep(dialTimeout - time.Since(startDial))
		}
	}
	return nil, fmt.Errorf("dialing remote: %w", err)
}


================================================
FILE: gopls/internal/lsprpc/export_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

// This file defines things (and opens backdoors) needed only by tests.

import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/xcontext"
)

const HandshakeMethod = handshakeMethod

// A ServerFunc is used to construct an LSP server for a given client.
type ServerFunc func(context.Context, protocol.ClientCloser) protocol.Server

type Canceler struct {
	Conn *jsonrpc2_v2.Connection
}

func (c *Canceler) Preempt(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
	if req.Method != "$/cancelRequest" {
		return nil, jsonrpc2_v2.ErrNotHandled
	}
	var params protocol.CancelParams
	if err := json.Unmarshal(req.Params, &params); err != nil {
		return nil, fmt.Errorf("%w: %v", jsonrpc2_v2.ErrParse, err)
	}
	id, err := jsonrpc2_v2.MakeID(params.ID)
	if err != nil {
		return nil, fmt.Errorf("%w: invalid ID type %T", jsonrpc2_v2.ErrParse, params.ID)
	}
	c.Conn.Cancel(id)
	return nil, nil
}

type ForwardBinder struct {
	dialer jsonrpc2_v2.Dialer
	onBind func(*jsonrpc2_v2.Connection)
}

func NewForwardBinder(dialer jsonrpc2_v2.Dialer) *ForwardBinder {
	return &ForwardBinder{
		dialer: dialer,
	}
}

func (b *ForwardBinder) Bind(ctx context.Context, conn *jsonrpc2_v2.Connection) (opts jsonrpc2_v2.ConnectionOptions) {
	client := protocol.ClientDispatcherV2(conn)
	clientBinder := NewClientBinder(func(context.Context, protocol.Server) protocol.Client { return client })

	serverConn, err := jsonrpc2_v2.Dial(context.Background(), b.dialer, clientBinder, nil)
	if err != nil {
		return jsonrpc2_v2.ConnectionOptions{
			Handler: jsonrpc2_v2.HandlerFunc(func(context.Context, *jsonrpc2_v2.Request) (any, error) {
				return nil, fmt.Errorf("%w: %v", jsonrpc2_v2.ErrInternal, err)
			}),
		}
	}

	if b.onBind != nil {
		b.onBind(serverConn)
	}
	server := protocol.ServerDispatcherV2(serverConn)
	preempter := &Canceler{
		Conn: conn,
	}
	detached := xcontext.Detach(ctx)
	go func() {
		conn.Wait() // ignore error
		if err := serverConn.Close(); err != nil {
			event.Log(detached, fmt.Sprintf("closing remote connection: %v", err))
		}
	}()
	return jsonrpc2_v2.ConnectionOptions{
		Handler:   protocol.ServerHandlerV2(server),
		Preempter: preempter,
	}
}

func NewClientBinder(newClient ClientFunc) *clientBinder {
	return &clientBinder{newClient}
}

// A ClientFunc is used to construct an LSP client for a given server.
type ClientFunc func(context.Context, protocol.Server) protocol.Client

// clientBinder binds an LSP client to an incoming connection.
type clientBinder struct {
	newClient ClientFunc
}

func (b *clientBinder) Bind(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
	server := protocol.ServerDispatcherV2(conn)
	client := b.newClient(ctx, server)
	return jsonrpc2_v2.ConnectionOptions{
		Handler: protocol.ClientHandlerV2(client),
	}
}

// HandlerMiddleware is a middleware that only modifies the jsonrpc2 handler.
type HandlerMiddleware func(jsonrpc2_v2.Handler) jsonrpc2_v2.Handler

// BindHandler transforms a HandlerMiddleware into a Middleware.
func BindHandler(hmw HandlerMiddleware) Middleware {
	return Middleware(func(binder jsonrpc2_v2.Binder) jsonrpc2_v2.Binder {
		return BinderFunc(func(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
			opts := binder.Bind(ctx, conn)
			opts.Handler = hmw(opts.Handler)
			return opts
		})
	})
}

// The BinderFunc type adapts a bind function to implement the jsonrpc2.Binder
// interface.
type BinderFunc func(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions

func (f BinderFunc) Bind(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
	return f(ctx, conn)
}

// Middleware defines a transformation of jsonrpc2 Binders, that may be
// composed to build jsonrpc2 servers.
type Middleware func(jsonrpc2_v2.Binder) jsonrpc2_v2.Binder

var GetGoEnv = getGoEnv


================================================
FILE: gopls/internal/lsprpc/goenv.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/internal/gocommand"
)

func getGoEnv(ctx context.Context, env map[string]any) (map[string]string, error) {
	var runEnv []string
	for k, v := range env {
		runEnv = append(runEnv, fmt.Sprintf("%s=%s", k, v))
	}
	runner := gocommand.Runner{}
	output, err := runner.Run(ctx, gocommand.Invocation{
		Verb: "env",
		Args: []string{"-json"},
		Env:  runEnv,
	})
	if err != nil {
		return nil, err
	}
	envmap := make(map[string]string)
	if err := json.Unmarshal(output.Bytes(), &envmap); err != nil {
		return nil, err
	}
	return envmap, nil
}


================================================
FILE: gopls/internal/lsprpc/goenv_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc_test

import (
	"context"
	"encoding/json"
	"fmt"
	"os"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/testenv"

	. "golang.org/x/tools/gopls/internal/lsprpc"
)

func GoEnvMiddleware() (Middleware, error) {
	return BindHandler(func(delegate jsonrpc2_v2.Handler) jsonrpc2_v2.Handler {
		return jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
			if req.Method == "initialize" {
				if err := addGoEnvToInitializeRequestV2(ctx, req); err != nil {
					event.Error(ctx, "adding go env to initialize", err)
				}
			}
			return delegate.Handle(ctx, req)
		})
	}), nil
}

// This function is almost identical to addGoEnvToInitializeRequest in lsprpc.go.
// Make changes in parallel.
func addGoEnvToInitializeRequestV2(ctx context.Context, req *jsonrpc2_v2.Request) error {
	var params protocol.ParamInitialize
	if err := json.Unmarshal(req.Params, &params); err != nil {
		return err
	}
	var opts map[string]any
	switch v := params.InitializationOptions.(type) {
	case nil:
		opts = make(map[string]any)
	case map[string]any:
		opts = v
	default:
		return fmt.Errorf("unexpected type for InitializationOptions: %T", v)
	}
	envOpt, ok := opts["env"]
	if !ok {
		envOpt = make(map[string]any)
	}
	env, ok := envOpt.(map[string]any)
	if !ok {
		return fmt.Errorf("env option is %T, expected a map", envOpt)
	}
	goenv, err := GetGoEnv(ctx, env)
	if err != nil {
		return err
	}
	// We don't want to propagate GOWORK unless explicitly set since that could mess with
	// path inference during cmd/go invocations, see golang/go#51825.
	_, goworkSet := os.LookupEnv("GOWORK")
	for govar, value := range goenv {
		if govar == "GOWORK" && !goworkSet {
			continue
		}
		env[govar] = value
	}
	opts["env"] = env
	params.InitializationOptions = opts
	raw, err := json.Marshal(params)
	if err != nil {
		return fmt.Errorf("marshaling updated options: %v", err)
	}
	req.Params = json.RawMessage(raw)
	return nil
}

type initServer struct {
	protocol.Server

	params *protocol.ParamInitialize
}

func (s *initServer) Initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
	s.params = params
	return &protocol.InitializeResult{}, nil
}

func TestGoEnvMiddleware(t *testing.T) {
	testenv.NeedsTool(t, "go")

	ctx := context.Background()

	server := &initServer{}
	env := new(TestEnv)
	defer env.Shutdown(t)
	l, _ := env.serve(ctx, t, staticServerBinder(server))
	mw, err := GoEnvMiddleware()
	if err != nil {
		t.Fatal(err)
	}
	binder := mw(NewForwardBinder(l.Dialer()))
	l, _ = env.serve(ctx, t, binder)
	conn := env.dial(ctx, t, l.Dialer(), noopBinder, true)
	dispatch := protocol.ServerDispatcherV2(conn)
	initParams := &protocol.ParamInitialize{}
	initParams.InitializationOptions = map[string]any{
		"env": map[string]any{
			"GONOPROXY": "example.com",
		},
	}
	if _, err := dispatch.Initialize(ctx, initParams); err != nil {
		t.Fatal(err)
	}

	if server.params == nil {
		t.Fatalf("initialize params are unset")
	}
	envOpts := server.params.InitializationOptions.(map[string]any)["env"].(map[string]any)

	// Check for an arbitrary Go variable. It should be set.
	if _, ok := envOpts["GOPRIVATE"]; !ok {
		t.Errorf("Go environment variable GOPRIVATE unset in initialization options")
	}
	// Check that the variable present in our user config was not overwritten.
	if got, want := envOpts["GONOPROXY"], "example.com"; got != want {
		t.Errorf("GONOPROXY=%q, want %q", got, want)
	}
}


================================================
FILE: gopls/internal/lsprpc/lsprpc.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package lsprpc implements a jsonrpc2.StreamServer that may be used to
// serve the LSP on a jsonrpc2 channel.
package lsprpc

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"maps"
	"net"
	"os"
	"slices"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
)

// Unique identifiers for client/server.
var serverIndex int64

// The streamServer type is a jsonrpc2.streamServer that handles incoming
// streams as a new LSP session, using a shared cache.
type StreamServer struct {
	cache *cache.Cache
	// daemon controls whether or not to log new connections.
	daemon bool

	// optionsOverrides is passed to newly created sessions.
	optionsOverrides func(*settings.Options)

	// onSessionExit is called whenever a session exits, with the session ID.
	onSessionExit func(id string)

	// serverForTest may be set to a test fake for testing.
	serverForTest protocol.Server

	// Keep track of active sessions, for interrogation.
	sessionMu sync.Mutex
	sessions  map[string]sessionServer
}

type sessionServer struct {
	session *cache.Session
	server  protocol.Server
}

// NewStreamServer creates a StreamServer using the shared cache. If
// withTelemetry is true, each session is instrumented with telemetry that
// records RPC statistics.
func NewStreamServer(cache *cache.Cache, daemon bool, optionsFunc func(*settings.Options)) *StreamServer {
	return &StreamServer{
		cache:            cache,
		daemon:           daemon,
		optionsOverrides: optionsFunc,
		sessions:         make(map[string]sessionServer),
	}
}

// SetSessionExitFunc sets the function to call when sessions exit.
// It is not concurrency safe, and must only be called at most once, before the
// receiver is passed to jsonrpc2.Serve.
func (s *StreamServer) SetSessionExitFunc(f func(id string)) {
	if s.onSessionExit != nil {
		panic("duplicate call to SetSessionExitFunc")
	}
	s.onSessionExit = f
}

// ServeStream implements the jsonrpc2.StreamServer interface, by handling
// incoming streams using a new lsp server.
func (s *StreamServer) ServeStream(ctx context.Context, conn jsonrpc2.Conn) error {
	client := protocol.ClientDispatcher(conn)
	session := cache.NewSession(ctx, s.cache)
	svr := s.serverForTest
	if svr == nil {
		options := settings.DefaultOptions(s.optionsOverrides)
		svr = server.New(session, client, options)
		if instance := debug.GetInstance(ctx); instance != nil {
			instance.AddService(svr, session)
		}
	}
	s.sessionMu.Lock()
	s.sessions[session.ID()] = sessionServer{session, svr}
	s.sessionMu.Unlock()
	defer func() {
		s.sessionMu.Lock()
		delete(s.sessions, session.ID())
		s.sessionMu.Unlock()
		if s.onSessionExit != nil {
			s.onSessionExit(session.ID())
		}
	}()

	// Clients may or may not send a shutdown message. Make sure the server is
	// shut down.
	// TODO(rFindley): this shutdown should perhaps be on a disconnected context.
	defer func() {
		if err := svr.Shutdown(ctx); err != nil {
			event.Error(ctx, "error shutting down", err)
		}
	}()
	executable, err := os.Executable()
	if err != nil {
		log.Printf("error getting gopls path: %v", err)
		executable = ""
	}
	ctx = protocol.WithClient(ctx, client)
	conn.Go(ctx,
		protocol.Handlers(
			handshaker(session, executable, s.daemon,
				protocol.ServerHandler(svr,
					jsonrpc2.MethodNotFound))))

	if s.daemon {
		log.Printf("Session %s: connected", session.ID())
		defer log.Printf("Session %s: exited", session.ID())
	}

	<-conn.Done()
	return conn.Err()
}

// Session returns the current active session for the given id, or (nil, nil)
// if none exists.
func (s *StreamServer) Session(id string) (*cache.Session, protocol.Server) {
	s.sessionMu.Lock()
	defer s.sessionMu.Unlock()
	ss := s.sessions[id]
	return ss.session, ss.server // possibly nil for zero value
}

// FirstSession returns the first session by lexically sorted session ID, or
// (nil, nil).
func (s *StreamServer) FirstSession() (*cache.Session, protocol.Server) {
	s.sessionMu.Lock()
	defer s.sessionMu.Unlock()
	keys := slices.Collect(maps.Keys(s.sessions))
	if len(keys) == 0 {
		return nil, nil
	}
	id := slices.Min(keys)
	ss := s.sessions[id]
	return ss.session, ss.server
}

// A forwarder is a jsonrpc2.StreamServer that handles an LSP stream by
// forwarding it to a remote. This is used when the gopls process started by
// the editor is in the `-remote` mode, which means it finds and connects to a
// separate gopls daemon. In these cases, we still want the forwarder gopls to
// be instrumented with telemetry, and want to be able to in some cases hijack
// the jsonrpc2 connection with the daemon.
type forwarder struct {
	dialer *autoDialer

	mu sync.Mutex
	// Hold on to the server connection so that we can redo the handshake if any
	// information changes.
	serverConn jsonrpc2.Conn
	serverID   string
}

// NewForwarder creates a new forwarder (a [jsonrpc2.StreamServer]),
// ready to forward connections to the
// remote server specified by rawAddr. If provided and rawAddr indicates an
// 'automatic' address (starting with 'auto;'), argFunc may be used to start a
// remote server for the auto-discovered address.
func NewForwarder(rawAddr string, argFunc func(network, address string) []string) (jsonrpc2.StreamServer, error) {
	dialer, err := newAutoDialer(rawAddr, argFunc)
	if err != nil {
		return nil, err
	}
	fwd := &forwarder{
		dialer: dialer,
	}
	return fwd, nil
}

// QueryServerState returns a JSON-encodable struct describing the state of the named server.
func QueryServerState(ctx context.Context, addr string) (any, error) {
	serverConn, err := dialRemote(ctx, addr)
	if err != nil {
		return nil, err
	}
	var state serverState
	if err := protocol.Call(ctx, serverConn, sessionsMethod, nil, &state); err != nil {
		return nil, fmt.Errorf("querying server state: %w", err)
	}
	return &state, nil
}

// dialRemote is used for making calls into the gopls daemon. addr should be a
// URL, possibly on the synthetic 'auto' network (e.g. tcp://..., unix://...,
// or auto://...).
func dialRemote(ctx context.Context, addr string) (jsonrpc2.Conn, error) {
	network, address := ParseAddr(addr)
	if network == autoNetwork {
		gp, err := os.Executable()
		if err != nil {
			return nil, fmt.Errorf("getting gopls path: %w", err)
		}
		network, address = autoNetworkAddress(gp, address)
	}
	netConn, err := net.DialTimeout(network, address, 5*time.Second)
	if err != nil {
		return nil, fmt.Errorf("dialing remote: %w", err)
	}
	serverConn := jsonrpc2.NewConn(jsonrpc2.NewHeaderStream(netConn))
	serverConn.Go(ctx, jsonrpc2.MethodNotFound)
	return serverConn, nil
}

// ExecuteCommand connects to the named server, sends it a
// workspace/executeCommand request (with command 'id' and arguments
// JSON encoded in 'request'), and populates the result variable.
func ExecuteCommand(ctx context.Context, addr string, id string, request, result any) error {
	serverConn, err := dialRemote(ctx, addr)
	if err != nil {
		return err
	}
	args, err := command.MarshalArgs(request)
	if err != nil {
		return err
	}
	params := protocol.ExecuteCommandParams{
		Command:   id,
		Arguments: args,
	}
	return protocol.Call(ctx, serverConn, "workspace/executeCommand", params, result)
}

// ServeStream dials the forwarder remote and binds the remote to serve the LSP
// on the incoming stream.
func (f *forwarder) ServeStream(ctx context.Context, clientConn jsonrpc2.Conn) error {
	client := protocol.ClientDispatcher(clientConn)

	netConn, err := f.dialer.dialNet(ctx)
	if err != nil {
		return fmt.Errorf("forwarder: connecting to remote: %w", err)
	}
	serverConn := jsonrpc2.NewConn(jsonrpc2.NewHeaderStream(netConn))
	server := protocol.ServerDispatcher(serverConn)

	// Forward between connections.
	serverConn.Go(ctx,
		protocol.Handlers(
			protocol.ClientHandler(client,
				jsonrpc2.MethodNotFound)))

	// Don't run the clientConn yet, so that we can complete the handshake before
	// processing any client messages.

	// Do a handshake with the server instance to exchange debug information.
	index := atomic.AddInt64(&serverIndex, 1)
	f.mu.Lock()
	f.serverConn = serverConn
	f.serverID = strconv.FormatInt(index, 10)
	f.mu.Unlock()
	f.handshake(ctx)
	clientConn.Go(ctx,
		protocol.Handlers(
			f.handler(
				protocol.ServerHandler(server,
					jsonrpc2.MethodNotFound))))

	select {
	case <-serverConn.Done():
		clientConn.Close() // ignore error
	case <-clientConn.Done():
		serverConn.Close() // ignore error
	}

	err = nil
	if serverConn.Err() != nil {
		err = fmt.Errorf("remote disconnected: %v", serverConn.Err())
	} else if clientConn.Err() != nil {
		err = fmt.Errorf("client disconnected: %v", clientConn.Err())
	}
	event.Log(ctx, fmt.Sprintf("forwarder: exited with error: %v", err))
	return err
}

// TODO(rfindley): remove this handshaking in favor of middleware.
func (f *forwarder) handshake(ctx context.Context) {
	// This call to os.Executable is redundant, and will be eliminated by the
	// transition to the V2 API.
	goplsPath, err := os.Executable()
	if err != nil {
		event.Error(ctx, "getting executable for handshake", err)
		goplsPath = ""
	}
	var (
		hreq = handshakeRequest{
			ServerID:  f.serverID,
			GoplsPath: goplsPath,
		}
		hresp handshakeResponse
	)
	if di := debug.GetInstance(ctx); di != nil {
		hreq.Logfile = di.Logfile
		hreq.DebugAddr = di.ListenedDebugAddress()
	}
	if err := protocol.Call(ctx, f.serverConn, handshakeMethod, hreq, &hresp); err != nil {
		// TODO(rfindley): at some point in the future we should return an error
		// here.  Handshakes have become functional in nature.
		event.Error(ctx, "forwarder: gopls handshake failed", err)
	}
	if hresp.GoplsPath != goplsPath {
		event.Error(ctx, "", fmt.Errorf("forwarder: gopls path mismatch: forwarder is %q, remote is %q", goplsPath, hresp.GoplsPath))
	}
	event.Log(ctx, "New server",
		label.NewServer.Of(f.serverID),
		label.Logfile.Of(hresp.Logfile),
		label.DebugAddress.Of(hresp.DebugAddr),
		label.GoplsPath.Of(hresp.GoplsPath),
		label.ClientID.Of(hresp.SessionID),
	)
}

func ConnectToRemote(ctx context.Context, addr string) (net.Conn, error) {
	dialer, err := newAutoDialer(addr, nil)
	if err != nil {
		return nil, err
	}
	return dialer.dialNet(ctx)
}

// handler intercepts messages to the daemon to enrich them with local
// information.
func (f *forwarder) handler(handler jsonrpc2.Handler) jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, r jsonrpc2.Request) error {
		// Intercept certain messages to add special handling.
		switch r.Method() {
		case "initialize":
			if newr, err := addGoEnvToInitializeRequest(ctx, r); err == nil {
				r = newr
			} else {
				log.Printf("unable to add local env to initialize request: %v", err)
			}
		case "workspace/executeCommand":
			var params protocol.ExecuteCommandParams
			if err := json.Unmarshal(r.Params(), &params); err == nil {
				if params.Command == command.StartDebugging.String() {
					var args command.DebuggingArgs
					if err := command.UnmarshalArgs(params.Arguments, &args); err == nil {
						reply = f.replyWithDebugAddress(ctx, reply, args)
					} else {
						event.Error(ctx, "unmarshaling debugging args", err)
					}
				}
			} else {
				event.Error(ctx, "intercepting executeCommand request", err)
			}
		}
		// The gopls workspace environment defaults to the process environment in
		// which gopls daemon was started. To avoid discrepancies in Go environment
		// between the editor and daemon, inject any unset variables in `go env`
		// into the options sent by initialize.
		//
		// See also golang.org/issue/37830.
		return handler(ctx, reply, r)
	}
}

// addGoEnvToInitializeRequest builds a new initialize request in which we set
// any environment variables output by `go env` and not already present in the
// request.
//
// It returns an error if r is not an initialize request, or is otherwise
// malformed.
func addGoEnvToInitializeRequest(ctx context.Context, r jsonrpc2.Request) (jsonrpc2.Request, error) {
	var params protocol.ParamInitialize
	if err := json.Unmarshal(r.Params(), &params); err != nil {
		return nil, err
	}
	var opts map[string]any
	switch v := params.InitializationOptions.(type) {
	case nil:
		opts = make(map[string]any)
	case map[string]any:
		opts = v
	default:
		return nil, fmt.Errorf("unexpected type for InitializationOptions: %T", v)
	}
	envOpt, ok := opts["env"]
	if !ok {
		envOpt = make(map[string]any)
	}
	env, ok := envOpt.(map[string]any)
	if !ok {
		return nil, fmt.Errorf(`env option is %T, expected a map`, envOpt)
	}
	goenv, err := getGoEnv(ctx, env)
	if err != nil {
		return nil, err
	}
	// We don't want to propagate GOWORK unless explicitly set since that could mess with
	// path inference during cmd/go invocations, see golang/go#51825.
	_, goworkSet := os.LookupEnv("GOWORK")
	for govar, value := range goenv {
		if govar == "GOWORK" && !goworkSet {
			continue
		}
		env[govar] = value
	}
	opts["env"] = env
	params.InitializationOptions = opts
	call, ok := r.(*jsonrpc2.Call)
	if !ok {
		return nil, fmt.Errorf("%T is not a *jsonrpc2.Call", r)
	}
	return jsonrpc2.NewCall(call.ID(), "initialize", params)
}

func (f *forwarder) replyWithDebugAddress(outerCtx context.Context, r jsonrpc2.Replier, args command.DebuggingArgs) jsonrpc2.Replier {
	di := debug.GetInstance(outerCtx)
	if di == nil {
		event.Log(outerCtx, "no debug instance to start")
		return r
	}
	return func(ctx context.Context, result any, outerErr error) error {
		if outerErr != nil {
			return r(ctx, result, outerErr)
		}
		// Enrich the result with our own debugging information. Since we're an
		// intermediary, the jsonrpc2 package has deserialized the result into
		// maps, by default. Re-do the unmarshalling.
		raw, err := json.Marshal(result)
		if err != nil {
			event.Error(outerCtx, "marshaling intermediate command result", err)
			return r(ctx, result, err)
		}
		var modified command.DebuggingResult
		if err := json.Unmarshal(raw, &modified); err != nil {
			event.Error(outerCtx, "unmarshaling intermediate command result", err)
			return r(ctx, result, err)
		}
		addr := args.Addr
		if addr == "" {
			addr = "localhost:0"
		}
		addr, err = di.Serve(outerCtx, addr)
		if err != nil {
			event.Error(outerCtx, "starting debug server", err)
			return r(ctx, result, err)
		}
		urls := []string{"http://" + addr}
		modified.URLs = append(urls, modified.URLs...)
		go f.handshake(ctx)
		return r(ctx, modified, nil)
	}
}

// A handshakeRequest identifies a client to the LSP server.
type handshakeRequest struct {
	// ServerID is the ID of the server on the client. This should usually be 0.
	ServerID string `json:"serverID"`
	// Logfile is the location of the clients log file.
	Logfile string `json:"logfile"`
	// DebugAddr is the client debug address.
	DebugAddr string `json:"debugAddr"`
	// GoplsPath is the path to the Gopls binary running the current client
	// process.
	GoplsPath string `json:"goplsPath"`
}

// A handshakeResponse is returned by the LSP server to tell the LSP client
// information about its session.
type handshakeResponse struct {
	// SessionID is the server session associated with the client.
	SessionID string `json:"sessionID"`
	// Logfile is the location of the server logs.
	Logfile string `json:"logfile"`
	// DebugAddr is the server debug address.
	DebugAddr string `json:"debugAddr"`
	// GoplsPath is the path to the Gopls binary running the current server
	// process.
	GoplsPath string `json:"goplsPath"`
}

// clientSession identifies a current client LSP session on the server. Note
// that it looks similar to handshakeResponse, but in fact 'Logfile' and
// 'DebugAddr' now refer to the client.
type clientSession struct {
	SessionID string `json:"sessionID"`
	Logfile   string `json:"logfile"`
	DebugAddr string `json:"debugAddr"`
}

// serverState holds information about the gopls daemon process, including its
// debug information and debug information of all of its current connected
// clients.
type serverState struct {
	Logfile         string          `json:"logfile"`
	DebugAddr       string          `json:"debugAddr"`
	GoplsPath       string          `json:"goplsPath"`
	CurrentClientID string          `json:"currentClientID"`
	Clients         []clientSession `json:"clients"`
}

const (
	handshakeMethod = "gopls/handshake"
	sessionsMethod  = "gopls/sessions"
)

func handshaker(session *cache.Session, goplsPath string, logHandshakes bool, handler jsonrpc2.Handler) jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, r jsonrpc2.Request) error {
		switch r.Method() {
		case handshakeMethod:
			// We log.Printf in this handler, rather than event.Log when we want logs
			// to go to the daemon log rather than being reflected back to the
			// client.
			var req handshakeRequest
			if err := json.Unmarshal(r.Params(), &req); err != nil {
				if logHandshakes {
					log.Printf("Error processing handshake for session %s: %v", session.ID(), err)
				}
				sendError(ctx, reply, err)
				return nil
			}
			if logHandshakes {
				log.Printf("Session %s: got handshake. Logfile: %q, Debug addr: %q", session.ID(), req.Logfile, req.DebugAddr)
			}
			event.Log(ctx, "Handshake session update",
				cache.KeyUpdateSession.Of(session),
				label.DebugAddress.Of(req.DebugAddr),
				label.Logfile.Of(req.Logfile),
				label.ServerID.Of(req.ServerID),
				label.GoplsPath.Of(req.GoplsPath),
			)
			resp := handshakeResponse{
				SessionID: session.ID(),
				GoplsPath: goplsPath,
			}
			if di := debug.GetInstance(ctx); di != nil {
				resp.Logfile = di.Logfile
				resp.DebugAddr = di.ListenedDebugAddress()
			}
			return reply(ctx, resp, nil)

		case sessionsMethod:
			resp := serverState{
				GoplsPath:       goplsPath,
				CurrentClientID: session.ID(),
			}
			if di := debug.GetInstance(ctx); di != nil {
				resp.Logfile = di.Logfile
				resp.DebugAddr = di.ListenedDebugAddress()
				for _, c := range di.State.Clients() {
					resp.Clients = append(resp.Clients, clientSession{
						SessionID: c.Session.ID(),
						Logfile:   c.Logfile,
						DebugAddr: c.DebugAddress,
					})
				}
			}
			return reply(ctx, resp, nil)
		}
		return handler(ctx, reply, r)
	}
}

func sendError(ctx context.Context, reply jsonrpc2.Replier, err error) {
	err = fmt.Errorf("%v: %w", err, jsonrpc2.ErrParse)
	if err := reply(ctx, nil, err); err != nil {
		event.Error(ctx, "", err)
	}
}

// ParseAddr parses the address of a gopls remote.
// TODO(rFindley): further document this syntax, and allow URI-style remote
// addresses such as "auto://...".
func ParseAddr(listen string) (network string, address string) {
	// Allow passing just -remote=auto, as a shorthand for using automatic remote
	// resolution.
	if listen == autoNetwork {
		return autoNetwork, ""
	}
	if parts := strings.SplitN(listen, ";", 2); len(parts) == 2 {
		return parts[0], parts[1]
	}
	return "tcp", listen
}


================================================
FILE: gopls/internal/lsprpc/lsprpc_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc

import (
	"context"
	"encoding/json"
	"errors"
	"regexp"
	"strings"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/testenv"
)

type FakeClient struct {
	protocol.Client

	Logs chan string
}

func (c FakeClient) LogMessage(ctx context.Context, params *protocol.LogMessageParams) error {
	c.Logs <- params.Message
	return nil
}

// fakeServer is intended to be embedded in the test fakes below, to trivially
// implement Shutdown.
type fakeServer struct {
	protocol.Server
}

func (fakeServer) Shutdown(ctx context.Context) error {
	return nil
}

type PingServer struct{ fakeServer }

func (s PingServer) DidOpen(ctx context.Context, params *protocol.DidOpenTextDocumentParams) error {
	event.Log(ctx, "ping")
	return nil
}

func TestClientLogging(t *testing.T) {
	ctx := t.Context()

	server := PingServer{}
	client := FakeClient{Logs: make(chan string, 10)}

	ctx = debug.WithInstance(ctx, "")
	ss := NewStreamServer(cache.New(nil), false, nil)
	ss.serverForTest = server
	ts := servertest.NewPipeServer(ss, nil)
	defer checkClose(t, ts.Close)
	cc := ts.Connect(ctx)
	cc.Go(ctx, protocol.ClientHandler(client, jsonrpc2.MethodNotFound))

	if err := protocol.ServerDispatcher(cc).DidOpen(ctx, &protocol.DidOpenTextDocumentParams{}); err != nil {
		t.Errorf("DidOpen: %v", err)
	}

	select {
	case got := <-client.Logs:
		want := "ping"
		matched, err := regexp.MatchString(want, got)
		if err != nil {
			t.Fatal(err)
		}
		if !matched {
			t.Errorf("got log %q, want a log containing %q", got, want)
		}

	case <-time.After(10 * time.Second):
		// Any timeout we enforce here is at the mercy
		// of the underlying operating system.
		// 1s was occasionally flaky; 10s should be better.
		t.Error("timeout waiting for client log")
	}
}

// WaitableServer instruments LSP request so that we can control their timing.
// The requests chosen are arbitrary: we simply needed one that blocks, and
// another that doesn't.
type WaitableServer struct {
	fakeServer

	Started   chan struct{}
	Completed chan error
}

func (s WaitableServer) Hover(ctx context.Context, _ *protocol.HoverParams) (_ *protocol.Hover, err error) {
	s.Started <- struct{}{}
	defer func() {
		s.Completed <- err
	}()
	select {
	case <-ctx.Done():
		return nil, errors.New("cancelled hover")
	case <-time.After(10 * time.Second):
	}
	return &protocol.Hover{}, nil
}

func (s WaitableServer) ResolveCompletionItem(_ context.Context, item *protocol.CompletionItem) (*protocol.CompletionItem, error) {
	return item, nil
}

func checkClose(t *testing.T, closer func() error) {
	t.Helper()
	if err := closer(); err != nil {
		t.Errorf("closing: %v", err)
	}
}

func setupForwarding(ctx context.Context, t *testing.T, s protocol.Server) (direct, forwarded servertest.Connector, cleanup func()) {
	t.Helper()
	serveCtx := debug.WithInstance(ctx, "")
	ss := NewStreamServer(cache.New(nil), false, nil)
	ss.serverForTest = s
	tsDirect := servertest.NewTCPServer(serveCtx, ss, nil)

	forwarder, err := NewForwarder("tcp;"+tsDirect.Addr, nil)
	if err != nil {
		t.Fatal(err)
	}
	tsForwarded := servertest.NewPipeServer(forwarder, nil)
	return tsDirect, tsForwarded, func() {
		checkClose(t, tsDirect.Close)
		checkClose(t, tsForwarded.Close)
	}
}

func TestRequestCancellation(t *testing.T) {
	ctx := context.Background()
	server := WaitableServer{
		Started:   make(chan struct{}),
		Completed: make(chan error),
	}
	tsDirect, tsForwarded, cleanup := setupForwarding(ctx, t, server)
	defer cleanup()
	tests := []struct {
		serverType string
		ts         servertest.Connector
	}{
		{"direct", tsDirect},
		{"forwarder", tsForwarded},
	}

	for _, test := range tests {
		t.Run(test.serverType, func(t *testing.T) {
			cc := test.ts.Connect(ctx)
			sd := protocol.ServerDispatcher(cc)
			cc.Go(ctx,
				protocol.Handlers(
					jsonrpc2.MethodNotFound))

			ctx := context.Background()
			ctx, cancel := context.WithCancel(ctx)

			result := make(chan error)
			go func() {
				_, err := sd.Hover(ctx, &protocol.HoverParams{})
				result <- err
			}()
			// Wait for the Hover request to start.
			<-server.Started
			cancel()
			if err := <-result; err == nil {
				t.Error("nil error for cancelled Hover(), want non-nil")
			}
			if err := <-server.Completed; err == nil || !strings.Contains(err.Error(), "cancelled hover") {
				t.Errorf("Hover(): unexpected server-side error %v", err)
			}
		})
	}
}

const exampleProgram = `
-- go.mod --
module mod

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}`

func TestDebugInfoLifecycle(t *testing.T) {
	sb, err := fake.NewSandbox(&fake.SandboxConfig{Files: fake.UnpackTxt(exampleProgram)})
	if err != nil {
		t.Fatal(err)
	}
	defer func() {
		if err := sb.Close(); err != nil {
			// TODO(golang/go#38490): we can't currently make this an error because
			// it fails on Windows: the workspace directory is still locked by a
			// separate Go process.
			// Once we have a reliable way to wait for proper shutdown, make this an
			// error.
			t.Logf("closing workspace failed: %v", err)
		}
	}()

	baseCtx := t.Context()
	clientCtx := debug.WithInstance(baseCtx, "")
	serverCtx := debug.WithInstance(baseCtx, "")

	ss := NewStreamServer(cache.New(nil), false, nil)
	tsBackend := servertest.NewTCPServer(serverCtx, ss, nil)

	forwarder, err := NewForwarder("tcp;"+tsBackend.Addr, nil)
	if err != nil {
		t.Fatal(err)
	}
	tsForwarder := servertest.NewPipeServer(forwarder, nil)

	ed1, err := fake.NewEditor(sb, fake.EditorConfig{}).Connect(clientCtx, tsForwarder, fake.ClientHooks{})
	if err != nil {
		t.Fatal(err)
	}
	defer ed1.Close(clientCtx)
	ed2, err := fake.NewEditor(sb, fake.EditorConfig{}).Connect(baseCtx, tsBackend, fake.ClientHooks{})
	if err != nil {
		t.Fatal(err)
	}
	defer ed2.Close(baseCtx)

	serverDebug := debug.GetInstance(serverCtx)
	if got, want := len(serverDebug.State.Clients()), 2; got != want {
		t.Errorf("len(server:Clients) = %d, want %d", got, want)
	}
	if got, want := len(serverDebug.State.Sessions()), 2; got != want {
		t.Errorf("len(server:Sessions) = %d, want %d", got, want)
	}
	clientDebug := debug.GetInstance(clientCtx)
	if got, want := len(clientDebug.State.Servers()), 1; got != want {
		t.Errorf("len(client:Servers) = %d, want %d", got, want)
	}
	// Close one of the connections to verify that the client and session were
	// dropped.
	if err := ed1.Close(clientCtx); err != nil {
		t.Fatal(err)
	}
	/*TODO: at this point we have verified the editor is closed
	However there is no way currently to wait for all associated go routines to
	go away, and we need to wait for those to trigger the client drop
	for now we just give it a little bit of time, but we need to fix this
	in a principled way
	*/
	start := time.Now()
	delay := time.Millisecond
	const maxWait = time.Second
	for len(serverDebug.State.Clients()) > 1 {
		if time.Since(start) > maxWait {
			break
		}
		time.Sleep(delay)
		delay *= 2
	}
	if got, want := len(serverDebug.State.Clients()), 1; got != want {
		t.Errorf("len(server:Clients) = %d, want %d", got, want)
	}
	if got, want := len(serverDebug.State.Sessions()), 1; got != want {
		t.Errorf("len(server:Sessions()) = %d, want %d", got, want)
	}
}

type initServer struct {
	fakeServer

	params *protocol.ParamInitialize
}

func (s *initServer) Initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
	s.params = params
	return &protocol.InitializeResult{}, nil
}

func TestEnvForwarding(t *testing.T) {
	testenv.NeedsTool(t, "go")

	ctx := context.Background()

	server := &initServer{}
	_, tsForwarded, cleanup := setupForwarding(ctx, t, server)
	defer cleanup()

	conn := tsForwarded.Connect(ctx)
	conn.Go(ctx, jsonrpc2.MethodNotFound)
	dispatch := protocol.ServerDispatcher(conn)
	initParams := &protocol.ParamInitialize{}
	initParams.InitializationOptions = map[string]any{
		"env": map[string]any{
			"GONOPROXY": "example.com",
		},
	}
	_, err := dispatch.Initialize(ctx, initParams)
	if err != nil {
		t.Fatal(err)
	}
	if server.params == nil {
		t.Fatalf("initialize params are unset")
	}
	env := server.params.InitializationOptions.(map[string]any)["env"].(map[string]any)

	// Check for an arbitrary Go variable. It should be set.
	if _, ok := env["GOPRIVATE"]; !ok {
		t.Errorf("Go environment variable GOPRIVATE unset in initialization options")
	}
	// Check that the variable present in our user config was not overwritten.
	if v := env["GONOPROXY"]; v != "example.com" {
		t.Errorf("GONOPROXY environment variable was overwritten")
	}
}

func TestListenParsing(t *testing.T) {
	tests := []struct {
		input, wantNetwork, wantAddr string
	}{
		{"127.0.0.1:0", "tcp", "127.0.0.1:0"},
		{"unix;/tmp/sock", "unix", "/tmp/sock"},
		{"auto", "auto", ""},
		{"auto;foo", "auto", "foo"},
	}

	for _, test := range tests {
		gotNetwork, gotAddr := ParseAddr(test.input)
		if gotNetwork != test.wantNetwork {
			t.Errorf("network = %q, want %q", gotNetwork, test.wantNetwork)
		}
		if gotAddr != test.wantAddr {
			t.Errorf("addr = %q, want %q", gotAddr, test.wantAddr)
		}
	}
}

// For #59479, verify that empty slices are serialized as [].
func TestEmptySlices(t *testing.T) {
	// The LSP would prefer that empty slices be sent as [] rather than null.
	const bad = `{"a":null}`
	const good = `{"a":[]}`
	var x struct {
		A []string `json:"a"`
	}
	buf, _ := json.Marshal(x)
	if string(buf) != bad {
		// uninitialized is ezpected to give null
		t.Errorf("unexpectedly got %s, want %s", buf, bad)
	}
	x.A = make([]string, 0)
	buf, _ = json.Marshal(x)
	if string(buf) != good {
		// expect []
		t.Errorf("unexpectedly got %s, want %s", buf, good)
	}
	x.A = []string{}
	buf, _ = json.Marshal(x)
	if string(buf) != good {
		// expect []
		t.Errorf("unexpectedly got %s, want %s", buf, good)
	}
}


================================================
FILE: gopls/internal/lsprpc/middleware_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lsprpc_test

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sync"
	"testing"
	"time"

	. "golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/internal/event"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

var noopBinder = BinderFunc(func(context.Context, *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
	return jsonrpc2_v2.ConnectionOptions{}
})

func TestHandshakeMiddleware(t *testing.T) {
	sh := &Handshaker{
		metadata: metadata{
			"answer": 42,
		},
	}
	ctx := context.Background()
	env := new(TestEnv)
	defer env.Shutdown(t)
	l, _ := env.serve(ctx, t, sh.Middleware(noopBinder))
	conn := env.dial(ctx, t, l.Dialer(), noopBinder, false)
	ch := &Handshaker{
		metadata: metadata{
			"question": 6 * 9,
		},
	}

	check := func(connected bool) error {
		clients := sh.Peers()
		servers := ch.Peers()
		want := 0
		if connected {
			want = 1
		}
		if got := len(clients); got != want {
			return fmt.Errorf("got %d clients on the server, want %d", got, want)
		}
		if got := len(servers); got != want {
			return fmt.Errorf("got %d servers on the client, want %d", got, want)
		}
		if !connected {
			return nil
		}
		client := clients[0]
		server := servers[0]
		if _, ok := client.Metadata["question"]; !ok {
			return errors.New("no client metadata")
		}
		if _, ok := server.Metadata["answer"]; !ok {
			return errors.New("no server metadata")
		}
		if client.LocalID != server.RemoteID {
			return fmt.Errorf("client.LocalID == %d, server.PeerID == %d", client.LocalID, server.RemoteID)
		}
		if client.RemoteID != server.LocalID {
			return fmt.Errorf("client.PeerID == %d, server.LocalID == %d", client.RemoteID, server.LocalID)
		}
		return nil
	}

	if err := check(false); err != nil {
		t.Fatalf("before handshake: %v", err)
	}
	ch.ClientHandshake(ctx, conn)
	if err := check(true); err != nil {
		t.Fatalf("after handshake: %v", err)
	}
	conn.Close() // ignore error
	// Wait for up to ~2s for connections to get cleaned up.
	delay := 25 * time.Millisecond
	for retries := 3; retries >= 0; retries-- {
		time.Sleep(delay)
		err := check(false)
		if err == nil {
			return
		}
		if retries == 0 {
			t.Fatalf("after closing connection: %v", err)
		}
		delay *= 4
	}
}

// Handshaker handles both server and client handshaking over jsonrpc2 v2.
// To instrument server-side handshaking, use Handshaker.Middleware.
// To instrument client-side handshaking, call
// Handshaker.ClientHandshake for any new client-side connections.
type Handshaker struct {
	// metadata will be shared with peers via handshaking.
	metadata metadata

	mu     sync.Mutex
	prevID int64
	peers  map[int64]PeerInfo
}

// metadata holds arbitrary data transferred between jsonrpc2 peers.
type metadata map[string]any

// PeerInfo holds information about a peering between jsonrpc2 servers.
type PeerInfo struct {
	// RemoteID is the identity of the current server on its peer.
	RemoteID int64

	// LocalID is the identity of the peer on the server.
	LocalID int64

	// IsClient reports whether the peer is a client. If false, the peer is a
	// server.
	IsClient bool

	// Metadata holds arbitrary information provided by the peer.
	Metadata metadata
}

// Peers returns the peer info this handshaker knows about by way of either the
// server-side handshake middleware, or client-side handshakes.
func (h *Handshaker) Peers() []PeerInfo {
	h.mu.Lock()
	defer h.mu.Unlock()

	var c []PeerInfo
	for _, v := range h.peers {
		c = append(c, v)
	}
	return c
}

// Middleware is a jsonrpc2 middleware function to augment connection binding
// to handle the handshake method, and record disconnections.
func (h *Handshaker) Middleware(inner jsonrpc2_v2.Binder) jsonrpc2_v2.Binder {
	return BinderFunc(func(ctx context.Context, conn *jsonrpc2_v2.Connection) jsonrpc2_v2.ConnectionOptions {
		opts := inner.Bind(ctx, conn)

		localID := h.nextID()
		info := &PeerInfo{
			RemoteID: localID,
			Metadata: h.metadata,
		}

		// Wrap the delegated handler to accept the handshake.
		delegate := opts.Handler
		opts.Handler = jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
			if req.Method == HandshakeMethod {
				var peerInfo PeerInfo
				if err := json.Unmarshal(req.Params, &peerInfo); err != nil {
					return nil, fmt.Errorf("%w: unmarshaling client info: %v", jsonrpc2_v2.ErrInvalidParams, err)
				}
				peerInfo.LocalID = localID
				peerInfo.IsClient = true
				h.recordPeer(peerInfo)
				return info, nil
			}
			return delegate.Handle(ctx, req)
		})

		// Record the dropped client.
		go h.cleanupAtDisconnect(conn, localID)

		return opts
	})
}

// ClientHandshake performs a client-side handshake with the server at the
// other end of conn, recording the server's peer info and watching for conn's
// disconnection.
func (h *Handshaker) ClientHandshake(ctx context.Context, conn *jsonrpc2_v2.Connection) {
	localID := h.nextID()
	info := &PeerInfo{
		RemoteID: localID,
		Metadata: h.metadata,
	}

	call := conn.Call(ctx, HandshakeMethod, info)
	var serverInfo PeerInfo
	if err := call.Await(ctx, &serverInfo); err != nil {
		event.Error(ctx, "performing handshake", err)
		return
	}
	serverInfo.LocalID = localID
	h.recordPeer(serverInfo)

	go h.cleanupAtDisconnect(conn, localID)
}

func (h *Handshaker) nextID() int64 {
	h.mu.Lock()
	defer h.mu.Unlock()

	h.prevID++
	return h.prevID
}

func (h *Handshaker) cleanupAtDisconnect(conn *jsonrpc2_v2.Connection, peerID int64) {
	conn.Wait() // ignore error

	h.mu.Lock()
	defer h.mu.Unlock()
	delete(h.peers, peerID)
}

func (h *Handshaker) recordPeer(info PeerInfo) {
	h.mu.Lock()
	defer h.mu.Unlock()
	if h.peers == nil {
		h.peers = make(map[int64]PeerInfo)
	}
	h.peers[info.LocalID] = info
}


================================================
FILE: gopls/internal/mcp/context.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

// This file defines the "context" operation, which returns a summary of the
// specified package.

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"slices"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/packagepath"
)

type ContextParams struct {
	File string `json:"file" jsonschema:"the absolute path to the file"`
}

func (h *handler) contextHandler(ctx context.Context, req *mcp.CallToolRequest, params ContextParams) (*mcp.CallToolResult, any, error) {
	countGoContextMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	// TODO(hxjiang): support context for GoMod.
	if snapshot.FileKind(fh) != file.Go {
		return nil, nil, fmt.Errorf("can't provide context for non-Go file")
	}

	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, nil, err
	}

	var result strings.Builder

	fmt.Fprintf(&result, "Current package %q (package %s):\n\n", pkg.Metadata().PkgPath, pkg.Metadata().Name)
	// Write context of the current file.
	{
		fmt.Fprintf(&result, "%s (current file):\n", pgf.URI.Base())
		result.WriteString("```go\n")
		if err := writeFileSummary(ctx, snapshot, pgf.URI, &result, false, nil); err != nil {
			return nil, nil, err
		}
		result.WriteString("```\n\n")
	}

	// Write context of the rest of the files in the current package.
	{
		for _, file := range pkg.CompiledGoFiles() {
			if file.URI == pgf.URI {
				continue
			}

			fmt.Fprintf(&result, "%s:\n", file.URI.Base())
			result.WriteString("```go\n")
			if err := writeFileSummary(ctx, snapshot, file.URI, &result, false, nil); err != nil {
				return nil, nil, err
			}
			result.WriteString("```\n\n")
		}
	}

	// Write dependencies context of current file.
	if len(pgf.File.Imports) > 0 {
		// Write import decls of the current file.
		{
			fmt.Fprintf(&result, "Current file %q contains this import declaration:\n", pgf.URI.Base())
			result.WriteString("```go\n")
			// Add all import decl to output including all floating comment by
			// using GenDecl's start and end position.
			for _, decl := range pgf.File.Decls {
				genDecl, ok := decl.(*ast.GenDecl)
				if !ok || genDecl.Tok != token.IMPORT {
					continue
				}

				text, err := pgf.NodeText(genDecl)
				if err != nil {
					return nil, nil, err
				}

				result.Write(text)
				result.WriteString("\n")
			}
			result.WriteString("```\n\n")
		}

		var toSummarize []*ast.ImportSpec
		for _, spec := range pgf.File.Imports {
			// Skip the standard library to reduce token usage, operating on
			// the assumption that the LLM is already familiar with its
			// symbols and documentation.
			if packagepath.IsStdPackage(spec.Path.Value) {
				continue
			}
			toSummarize = append(toSummarize, spec)
		}

		// Write summaries from imported packages.
		if len(toSummarize) > 0 {
			result.WriteString("The imported packages declare the following symbols:\n\n")
			for _, spec := range toSummarize {
				path := metadata.UnquoteImportPath(spec)
				id := pkg.Metadata().DepsByImpPath[path]
				if id == "" {
					continue // ignore error
				}
				md := snapshot.Metadata(id)
				if md == nil {
					continue // ignore error
				}
				if summary := summarizePackage(ctx, snapshot, md); summary != "" {
					result.WriteString(summary)
				}
			}
		}
	}

	return textResult(result.String()), nil, nil
}

func summarizePackage(ctx context.Context, snapshot *cache.Snapshot, md *metadata.Package) string {
	var buf strings.Builder
	fmt.Fprintf(&buf, "%q (package %s)\n", md.PkgPath, md.Name)
	for _, f := range md.CompiledGoFiles {
		fmt.Fprintf(&buf, "%s:\n", f.Base())
		buf.WriteString("```go\n")
		if err := writeFileSummary(ctx, snapshot, f, &buf, true, nil); err != nil {
			return "" // ignore error
		}
		buf.WriteString("```\n\n")
	}
	return buf.String()
}

// writeFileSummary writes the file summary to the string builder based on
// the input file URI.
func writeFileSummary(ctx context.Context, snapshot *cache.Snapshot, f protocol.DocumentURI, out *strings.Builder, onlyExported bool, declsToSummarize map[string]bool) error {
	fh, err := snapshot.ReadFile(ctx, f)
	if err != nil {
		return err
	}
	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return err
	}

	// If we're summarizing specific declarations, we don't need to copy the header.
	if declsToSummarize == nil {
		// Copy everything before the first non-import declaration:
		// package decl, imports decl(s), and all comments (excluding copyright).
		{
			endPos := pgf.File.FileEnd

		outerloop:
			for _, decl := range pgf.File.Decls {
				switch decl := decl.(type) {
				case *ast.FuncDecl:
					if decl.Doc != nil {
						endPos = decl.Doc.Pos()
					} else {
						endPos = decl.Pos()
					}
					break outerloop
				case *ast.GenDecl:
					if decl.Tok == token.IMPORT {
						continue
					}
					if decl.Doc != nil {
						endPos = decl.Doc.Pos()
					} else {
						endPos = decl.Pos()
					}
					break outerloop
				}
			}

			startPos := pgf.File.FileStart
			if copyright := golang.CopyrightComment(pgf.File); copyright != nil {
				startPos = copyright.End()
			}

			text, err := pgf.PosText(startPos, endPos)
			if err != nil {
				return err
			}

			out.Write(bytes.TrimSpace(text))
			out.WriteString("\n\n")
		}
	}

	// Write func decl and gen decl.
	for _, decl := range pgf.File.Decls {
		switch decl := decl.(type) {
		case *ast.FuncDecl:
			if declsToSummarize != nil {
				if _, ok := declsToSummarize[decl.Name.Name]; !ok {
					continue
				}
			}
			if onlyExported {
				if !decl.Name.IsExported() {
					continue
				}

				if decl.Recv != nil && len(decl.Recv.List) > 0 {
					_, rname, _ := astutil.UnpackRecv(decl.Recv.List[0].Type)
					if !rname.IsExported() {
						continue
					}
				}
			}

			// Write doc comment and func signature.
			startPos := decl.Pos()
			if decl.Doc != nil {
				startPos = decl.Doc.Pos()
			}

			text, err := pgf.PosText(startPos, decl.Type.End())
			if err != nil {
				return err
			}

			out.Write(text)
			out.WriteString("\n\n")

		case *ast.GenDecl:
			if decl.Tok == token.IMPORT {
				continue
			}

			// If we are summarizing specific decls, check if any of them are in this GenDecl.
			if declsToSummarize != nil {
				found := false
				for _, spec := range decl.Specs {
					switch spec := spec.(type) {
					case *ast.TypeSpec:
						if _, ok := declsToSummarize[spec.Name.Name]; ok {
							found = true
						}
					case *ast.ValueSpec:
						for _, name := range spec.Names {
							if _, ok := declsToSummarize[name.Name]; ok {
								found = true
							}
						}
					}
				}
				if !found {
					continue
				}
			}

			// Dump the entire GenDecl (exported or unexported)
			// including doc comment without any filtering to the output.
			if !onlyExported {
				startPos := decl.Pos()
				if decl.Doc != nil {
					startPos = decl.Doc.Pos()
				}
				text, err := pgf.PosText(startPos, decl.End())
				if err != nil {
					return err
				}

				out.Write(text)
				out.WriteString("\n")
				continue
			}

			// Write only the GenDecl with exported identifier to the output.
			var buf bytes.Buffer
			if decl.Doc != nil {
				text, err := pgf.NodeText(decl.Doc)
				if err != nil {
					return err
				}
				buf.Write(text)
				buf.WriteString("\n")
			}

			buf.WriteString(decl.Tok.String() + " ")
			if decl.Lparen.IsValid() {
				buf.WriteString("(\n")
			}

			var anyExported bool
			for _, spec := range decl.Specs {
				// Captures the full byte range of the spec, including
				// its associated doc comments and line comments.
				// This range also covers any floating comments as these
				// can be valuable for context. Like
				// ```
				// type foo struct { // floating comment.
				// 		// floating comment.
				//
				// 		x int
				// }
				// ```
				var startPos, endPos token.Pos

				switch spec := spec.(type) {
				case *ast.TypeSpec:
					if declsToSummarize != nil {
						if _, ok := declsToSummarize[spec.Name.Name]; !ok {
							continue
						}
					}
					// TODO(hxjiang): only keep the exported field of
					// struct spec and exported method of interface spec.
					if !spec.Name.IsExported() {
						continue
					}
					anyExported = true

					// Include preceding doc comment, if any.
					if spec.Doc == nil {
						startPos = spec.Pos()
					} else {
						startPos = spec.Doc.Pos()
					}

					// Include trailing line comment, if any.
					if spec.Comment == nil {
						endPos = spec.End()
					} else {
						endPos = spec.Comment.End()
					}

				case *ast.ValueSpec:
					if declsToSummarize != nil {
						found := false
						for _, name := range spec.Names {
							if _, ok := declsToSummarize[name.Name]; ok {
								found = true
							}
						}
						if !found {
							continue
						}
					}
					// TODO(hxjiang): only keep the exported identifier.
					if !slices.ContainsFunc(spec.Names, (*ast.Ident).IsExported) {
						continue
					}
					anyExported = true

					if spec.Doc == nil {
						startPos = spec.Pos()
					} else {
						startPos = spec.Doc.Pos()
					}

					if spec.Comment == nil {
						endPos = spec.End()
					} else {
						endPos = spec.Comment.End()
					}
				}

				indent, err := pgf.Indentation(startPos)
				if err != nil {
					return err
				}

				buf.WriteString(indent)

				text, err := pgf.PosText(startPos, endPos)
				if err != nil {
					return err
				}

				buf.Write(text)
				buf.WriteString("\n")
			}

			if decl.Lparen.IsValid() {
				buf.WriteString(")\n")
			}

			// Only write the summary of the genDecl if there is
			// any exported spec.
			if anyExported {
				out.Write(buf.Bytes())
				out.WriteString("\n")
			}
		}
	}
	return nil
}


================================================
FILE: gopls/internal/mcp/counters.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import "golang.org/x/telemetry/counter"

// Proposed counters for evaluating usage of Go MCP Server tools. These counters
// increment when a user utilizes a specific Go MCP tool.
var (
	countGoContextMCP          = counter.New("gopls/mcp-tool:go_context")
	countGoDiagnosticsMCP      = counter.New("gopls/mcp-tool:go_diagnostics")
	countGoFileContextMCP      = counter.New("gopls/mcp-tool:go_file_context")
	countGoFileDiagnosticsMCP  = counter.New("gopls/mcp-tool:go_file_diagnostics")
	countGoFileMetadataMCP     = counter.New("gopls/mcp-tool:go_file_metadata")
	countGoPackageAPIMCP       = counter.New("gopls/mcp-tool:go_package_api")
	countGoReferencesMCP       = counter.New("gopls/mcp-tool:go_references")
	countGoRenameSymbolMCP     = counter.New("gopls/mcp-tool:go_rename_symbol")
	countGoSearchMCP           = counter.New("gopls/mcp-tool:go_search")
	countGoSymbolReferencesMCP = counter.New("gopls/mcp-tool:go_symbol_references")
	countGoWorkspaceMCP        = counter.New("gopls/mcp-tool:go_workspace")
	countGoVulncheckMCP        = counter.New("gopls/mcp-tool:go_vulncheck")
)


================================================
FILE: gopls/internal/mcp/file_context.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"go/ast"
	"go/types"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
)

type fileContextParams struct {
	File string `json:"file" jsonschema:"the absolute path to the file"`
}

func (h *handler) fileContextHandler(ctx context.Context, req *mcp.CallToolRequest, params fileContextParams) (*mcp.CallToolResult, any, error) {
	countGoFileContextMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, nil, err
	}

	info := pkg.TypesInfo()
	if info == nil {
		return nil, nil, fmt.Errorf("no types info for package %q", pkg.Metadata().PkgPath)
	}

	// Group objects defined in other files by file URI.
	otherFiles := make(map[protocol.DocumentURI]map[string]bool)
	addObj := func(obj types.Object) {
		if obj == nil {
			return
		}
		pos := obj.Pos()
		if !pos.IsValid() {
			return
		}
		objFile := pkg.FileSet().File(pos)
		if objFile == nil {
			return
		}
		uri := protocol.URIFromPath(objFile.Name())
		if uri == fh.URI() {
			return
		}
		if _, ok := otherFiles[uri]; !ok {
			otherFiles[uri] = make(map[string]bool)
		}
		otherFiles[uri][obj.Name()] = true
	}

	for cur := range pgf.Cursor().Preorder((*ast.Ident)(nil)) {
		id := cur.Node().(*ast.Ident)
		addObj(info.Uses[id])
		addObj(info.Defs[id])
	}

	var result strings.Builder
	fmt.Fprintf(&result, "File `%s` is in package %q.\n", params.File, pkg.Metadata().PkgPath)
	fmt.Fprintf(&result, "Below is a summary of the APIs it uses from other files.\n")
	fmt.Fprintf(&result, "To read the full API of any package, use go_package_api.\n")
	for uri, decls := range otherFiles {
		pkgPath := "UNKNOWN"
		md, err := snapshot.NarrowestMetadataForFile(ctx, uri)
		if err != nil {
			if ctx.Err() != nil {
				return nil, nil, ctx.Err()
			}
		} else {
			pkgPath = string(md.PkgPath)
		}
		fmt.Fprintf(&result, "Referenced declarations from %s (package %q):\n", uri.Path(), pkgPath)
		result.WriteString("```go\n")
		if err := writeFileSummary(ctx, snapshot, uri, &result, false, decls); err != nil {
			return nil, nil, err
		}
		result.WriteString("```\n\n")
	}

	return textResult(result.String()), nil, nil
}


================================================
FILE: gopls/internal/mcp/file_diagnostics.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

// This file defines the "diagnostics" operation, which is responsible for
// returning diagnostics for the input file.

import (
	"bytes"
	"context"
	"fmt"
	"path/filepath"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/diff"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

type diagnosticsParams struct {
	File string `json:"file" jsonschema:"the absolute path to the file to diagnose"`
}

func (h *handler) fileDiagnosticsHandler(ctx context.Context, req *mcp.CallToolRequest, params diagnosticsParams) (*mcp.CallToolResult, any, error) {
	countGoFileDiagnosticsMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	diagnostics, fixes, err := h.diagnoseFile(ctx, snapshot, fh.URI())
	if err != nil {
		return nil, nil, err
	}

	var builder strings.Builder
	if len(diagnostics) == 0 {
		return textResult("No diagnostics"), nil, nil
	}

	if err := summarizeDiagnostics(ctx, snapshot, &builder, diagnostics, fixes); err != nil {
		return nil, nil, err
	}

	return textResult(builder.String()), nil, nil
}

// diagnoseFile diagnoses a single file, including go/analysis and quick fixes.
func (h *handler) diagnoseFile(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) ([]*cache.Diagnostic, map[*cache.Diagnostic]*protocol.CodeAction, error) {
	diagnostics, err := golang.DiagnoseFile(ctx, snapshot, uri)
	if err != nil {
		return nil, nil, err
	}
	if len(diagnostics) == 0 {
		return nil, nil, nil
	}

	// LSP [protocol.Diagnostic]s do not carry code edits directly.
	// Instead, gopls provides associated [protocol.CodeAction]s with their
	// diagnostics field populated.
	// Ignore errors. It is still valuable to provide only the diagnostic
	// without any text edits.
	// TODO(hxjiang): support code actions that returns call back command.
	actions, _ := h.lspServer.CodeAction(ctx, &protocol.CodeActionParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: uri,
		},
		Context: protocol.CodeActionContext{
			Only:        []protocol.CodeActionKind{protocol.QuickFix},
			Diagnostics: cache.ToProtocolDiagnostics(diagnostics...),
		},
	})

	type key struct {
		Message string
		Range   protocol.Range
	}

	actionMap := make(map[key]*protocol.CodeAction)
	for _, action := range actions {
		for _, d := range action.Diagnostics {
			k := key{d.Message, d.Range}
			if alt, ok := actionMap[k]; !ok || !alt.IsPreferred && action.IsPreferred {
				actionMap[k] = &action
			}
		}
	}

	fixes := make(map[*cache.Diagnostic]*protocol.CodeAction)
	for _, d := range diagnostics {
		if fix, ok := actionMap[key{d.Message, d.Range}]; ok {
			fixes[d] = fix
		}
	}
	return diagnostics, fixes, nil
}

func summarizeDiagnostics(ctx context.Context, snapshot *cache.Snapshot, w *strings.Builder, diagnostics []*cache.Diagnostic, fixes map[*cache.Diagnostic]*protocol.CodeAction) error {
	for _, d := range diagnostics {
		fmt.Fprintf(w, "%d:%d-%d:%d: [%s] %s\n", d.Range.Start.Line, d.Range.Start.Character, d.Range.End.Line, d.Range.End.Character, d.Severity, d.Message)

		fix, ok := fixes[d]
		if ok && fix.Edit != nil {
			w.WriteString("Fix:\n")
			if err := writeUnifiedDiff(ctx, snapshot, w, fix.Edit.DocumentChanges); err != nil {
				return err
			}
			w.WriteString("\n")
		}
	}
	return nil
}

// writeUnifiedDiff converts each [protocol.DocumentChange] into a separate
// unified diff and write to the input writer.
//
// All returned diffs use forward slash ('/') as the file path separator for
// consistency, regardless of the original system's separator.
// Multiple changes targeting the same file are not consolidated.
//
// TODO(hxjiang): consolidate diffs to the same file.
func writeUnifiedDiff(ctx context.Context, snapshot *cache.Snapshot, w *strings.Builder, changes []protocol.DocumentChange) error {
	for _, change := range changes {
		// The before-and-after states for the file change.
		var (
			oldFile, newFile       string
			oldContent, newContent string
		)
		switch {
		case change.CreateFile != nil:
			oldFile, newFile = "/dev/null", filepath.ToSlash(change.CreateFile.URI.Path())
			oldContent, newContent = "", ""
		case change.DeleteFile != nil:
			fh, err := snapshot.ReadFile(ctx, change.DeleteFile.URI)
			if err != nil {
				return err
			}
			content, err := fh.Content()
			if err != nil {
				return err
			}
			oldFile, newFile = filepath.ToSlash(change.DeleteFile.URI.Path()), "/dev/null"
			oldContent, newContent = string(content), ""
		case change.RenameFile != nil:
			fh, err := snapshot.ReadFile(ctx, change.RenameFile.OldURI)
			if err != nil {
				return err
			}
			content, err := fh.Content()
			if err != nil {
				return err
			}
			oldFile = filepath.ToSlash(change.RenameFile.OldURI.Path())
			newFile = filepath.ToSlash(change.RenameFile.NewURI.Path())
			oldContent, newContent = string(content), string(content)
		case change.TextDocumentEdit != nil:
			fh, err := snapshot.ReadFile(ctx, change.TextDocumentEdit.TextDocument.URI)
			if err != nil {
				return err
			}

			// Assumes gopls never return AnnotatedTextEdit.
			sorted := protocol.AsTextEdits(change.TextDocumentEdit.Edits)

			// As stated by the LSP, text edits ranges must never overlap.
			// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textEditArray
			slices.SortStableFunc(sorted, func(a, b protocol.TextEdit) int {
				return protocol.CompareRange(a.Range, b.Range)
			})

			content, err := fh.Content()
			if err != nil {
				return err
			}

			var newSrc bytes.Buffer
			{
				mapper := protocol.NewMapper(fh.URI(), content)

				start := 0
				for _, edit := range sorted {
					l, r, err := mapper.RangeOffsets(edit.Range)
					if err != nil {
						return err
					}

					newSrc.Write(content[start:l])
					newSrc.WriteString(edit.NewText)

					start = r
				}
				newSrc.Write(content[start:])
			}

			oldFile, newFile = filepath.ToSlash(fh.URI().Path()), filepath.ToSlash(fh.URI().Path())
			oldContent, newContent = string(content), newSrc.String()
		default:
			continue // this shouldn't happen
		}
		w.WriteString(diff.Unified(oldFile, newFile, oldContent, newContent))
		w.WriteString("\n")
	}
	return nil
}


================================================
FILE: gopls/internal/mcp/file_metadata.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
)

type fileMetadataParams struct {
	File string `json:"file" jsonschema:"the absolute path to the file to describe"`
}

func (h *handler) fileMetadataHandler(ctx context.Context, req *mcp.CallToolRequest, params fileMetadataParams) (*mcp.CallToolResult, any, error) {
	countGoFileMetadataMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	md, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI())
	if err != nil {
		return nil, nil, err
	}

	var b strings.Builder
	addf := func(format string, args ...any) {
		fmt.Fprintf(&b, format, args...)
	}
	addf("File `%s` is in package %q, which has the following files:\n", params.File, md.PkgPath)
	for _, f := range md.CompiledGoFiles {
		addf("\t%s\n", f.Path())
	}
	return textResult(b.String()), nil, nil
}


================================================
FILE: gopls/internal/mcp/instructions.md
================================================
# The gopls MCP server

These instructions describe how to efficiently work in the Go programming language using the gopls MCP server. You can load this file directly into a session where the gopls MCP server is connected.

## Detecting a Go workspace

At the start of every session, you MUST use the `go_workspace` tool to learn about the Go workspace. ONLY if you are in a Go workspace, you MUST run `go_vulncheck` immediately afterwards to identify any existing security risks. The rest of these instructions apply whenever that tool indicates that the user is in a Go workspace.

## Go programming workflows

These guidelines MUST be followed whenever working in a Go workspace. There are two workflows described below: the 'Read Workflow' must be followed when the user asks a question about a Go workspace. The 'Edit Workflow' must be followed when the user edits a Go workspace.

You may re-do parts of each workflow as necessary to recover from errors. However, you must not skip any steps.

### Read workflow

The goal of the read workflow is to understand the codebase.

1. **Understand the workspace layout**: Start by using `go_workspace` to understand the overall structure of the workspace, such as whether it's a module, a workspace, or a GOPATH project.

2. **Find relevant symbols**: If you're looking for a specific type, function, or variable, use `go_search`. This is a fuzzy search that will help you locate symbols even if you don't know the exact name or location.
   EXAMPLE: search for the 'Server' type: `go_search({"query":"server"})`

3. **Understand a file and its intra-package dependencies**: When you have a file path and want to understand its contents and how it connects to other files *in the same package*, use `go_file_context`. This tool will show you a summary of the declarations from other files in the same package that are used by the current file. `go_file_context` MUST be used immediately after reading any Go file for the first time, and MAY be re-used if dependencies have changed.
   EXAMPLE: to understand `server.go`'s dependencies on other files in its package: `go_file_context({"file":"/path/to/server.go"})`

4. **Understand a package's public API**: When you need to understand what a package provides to external code (i.e., its public API), use `go_package_api`. This is especially useful for understanding third-party dependencies or other packages in the same monorepo.
   EXAMPLE: to see the API of the `storage` package: `go_package_api({"packagePaths":["example.com/internal/storage"]})`

### Editing workflow

The editing workflow is iterative. You should cycle through these steps until the task is complete.

1. **Read first**: Before making any edits, follow the Read Workflow to understand the user's request and the relevant code.

2. **Find references**: Before modifying the definition of any symbol, use the `go_symbol_references` tool to find all references to that identifier. This is critical for understanding the impact of your change. Read the files containing references to evaluate if any further edits are required.
   EXAMPLE: `go_symbol_references({"file":"/path/to/server.go","symbol":"Server.Run"})`

3. **Make edits**: Make the required edits, including edits to references you identified in the previous step. Don't proceed to the next step until all planned edits are complete.

4. **Check for errors**: After every code modification, you MUST call the `go_diagnostics` tool. Pass the paths of the files you have edited. This tool will report any build or analysis errors.
   EXAMPLE: `go_diagnostics({"files":["/path/to/server.go"]})`

5. **Fix errors**: If `go_diagnostics` reports any errors, fix them. The tool may provide suggested quick fixes in the form of diffs. You should review these diffs and apply them if they are correct. Once you've applied a fix, re-run `go_diagnostics` to confirm that the issue is resolved. It is OK to ignore 'hint' or 'info' diagnostics if they are not relevant to the current task. Note that Go diagnostic messages may contain a summary of the source code, which may not match its exact text.

6. **Check for vulnerabilities**: If your edits involved adding or updating dependencies in the go.mod file, you MUST run a vulnerability check on the entire workspace. This ensures that the new dependencies do not introduce any security risks. This step should be performed after all build errors are resolved. EXAMPLE: `go_vulncheck({"pattern":"./..."})`

7. **Run tests**: Once `go_diagnostics` reports no errors (and ONLY once there are no errors), run the tests for the packages you have changed. You can do this with `go test [packagePath...]`. Don't run `go test ./...` unless the user explicitly requests it, as doing so may slow down the iteration loop.



================================================
FILE: gopls/internal/mcp/mcp.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	_ "embed"
	"fmt"
	"io"
	"log"
	"net"
	"net/http"
	"os"
	"sync"

	"github.com/google/jsonschema-go/jsonschema"
	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/moremaps"
)

//go:embed instructions.md
var Instructions string

// A handler implements various MCP tools for an LSP session.
type handler struct {
	session   *cache.Session
	lspServer protocol.Server
}

// Sessions is the interface used to access gopls sessions.
type Sessions interface {
	Session(id string) (*cache.Session, protocol.Server)
	FirstSession() (*cache.Session, protocol.Server)
	SetSessionExitFunc(func(string))
}

// Serve starts an MCP server serving at the input address.
//
// The server receives LSP session events on the specified channel, which the
// caller is responsible for closing. The server runs until the context is
// canceled.
//
// The rootsHandler callback is invoked immediately after initialization and
// subsequently whenever the MCP client signals a change to the workspace roots.
// It is passed the list roots result returned by the MCP client, or an error
// if the roots could not be retrieved. rootsHandler may be called concurrently.
func Serve(ctx context.Context, address string, sessions Sessions, isDaemon bool, rootsHandler func(*mcp.ListRootsResult, error)) error {
	log.Printf("Gopls MCP server: starting up on http")
	listener, err := net.Listen("tcp", address)
	if err != nil {
		return err
	}
	defer listener.Close()

	// TODO(hxjiang): expose the MCP server address to the LSP client.
	if isDaemon {
		log.Printf("Gopls MCP daemon: listening on address %s...", listener.Addr())
	}
	defer log.Printf("Gopls MCP server: exiting")

	svr := http.Server{
		Handler: HTTPHandler(sessions, isDaemon, rootsHandler),
		BaseContext: func(net.Listener) context.Context {
			return ctx
		},
	}

	// Run the server until cancellation.
	go func() {
		<-ctx.Done()
		svr.Close() // ignore error
	}()
	log.Printf("mcp http server listening")
	return svr.Serve(listener)
}

// StartStdIO starts an MCP server over stdio.
func StartStdIO(ctx context.Context, session *cache.Session, server protocol.Server, rpcLog io.Writer, rootsHandler func(*mcp.ListRootsResult, error)) error {
	s := NewServer(session, server, rootsHandler)
	if rpcLog != nil {
		return s.Run(ctx, &mcp.LoggingTransport{
			Transport: &mcp.StdioTransport{},
			Writer:    rpcLog,
		})
	} else {
		return s.Run(ctx, &mcp.StdioTransport{})
	}

}

func HTTPHandler(sessions Sessions, isDaemon bool, rootsHandler func(*mcp.ListRootsResult, error)) http.Handler {
	var (
		mu          sync.Mutex                         // lock for mcpHandlers.
		mcpHandlers = make(map[string]*mcp.SSEHandler) // map from lsp session ids to MCP sse handlers.
	)
	mux := http.NewServeMux()

	// In daemon mode, gopls serves mcp server at ADDRESS/sessions/$SESSIONID.
	// Otherwise, gopls serves mcp server at ADDRESS.
	if isDaemon {
		mux.HandleFunc("/sessions/{id}", func(w http.ResponseWriter, r *http.Request) {
			sessionID := r.PathValue("id")

			mu.Lock()
			handler, ok := mcpHandlers[sessionID]
			if !ok {
				if s, svr := sessions.Session(sessionID); s != nil {
					handler = mcp.NewSSEHandler(func(request *http.Request) *mcp.Server {
						return NewServer(s, svr, rootsHandler)
					}, nil)
					mcpHandlers[sessionID] = handler
				}
			}
			mu.Unlock()

			if handler == nil {
				http.Error(w, fmt.Sprintf("session %s not established", sessionID), http.StatusNotFound)
				return
			}

			handler.ServeHTTP(w, r)
		})
	} else {
		// TODO(hxjiang): should gopls serve only at a specific path?
		mux.HandleFunc("/", func(w http.ResponseWriter, r *http.Request) {
			mu.Lock()
			// When not in daemon mode, gopls has at most one LSP session.
			_, handler, ok := moremaps.Arbitrary(mcpHandlers)
			if !ok {
				s, svr := sessions.FirstSession()
				handler = mcp.NewSSEHandler(func(request *http.Request) *mcp.Server {
					return NewServer(s, svr, rootsHandler)
				}, nil)
				mcpHandlers[s.ID()] = handler
			}
			mu.Unlock()

			if handler == nil {
				http.Error(w, "session not established", http.StatusNotFound)
				return
			}

			handler.ServeHTTP(w, r)
		})
	}
	sessions.SetSessionExitFunc(func(sessionID string) {
		mu.Lock()
		defer mu.Unlock()
		// TODO(rfindley): add a way to close SSE handlers (and therefore
		// close their transports). Otherwise, we leak JSON-RPC goroutines.
		delete(mcpHandlers, sessionID)
	})
	return mux
}

func NewServer(session *cache.Session, lspServer protocol.Server, rootsHandler func(*mcp.ListRootsResult, error)) *mcp.Server {
	h := handler{
		session:   session,
		lspServer: lspServer,
	}
	opts := &mcp.ServerOptions{
		Instructions: Instructions,
	}
	mcpServer := mcp.NewServer(&mcp.Implementation{Name: "gopls", Version: "v1.0.0"}, opts)

	defaultTools := []string{
		"go_workspace",
		"go_package_api",
		"go_diagnostics",
		"go_rename_symbol",
		"go_symbol_references",
		"go_search",
		"go_file_context",
		"go_vulncheck"}
	disabledTools := append(defaultTools,
		// The fileMetadata tool is redundant with fileContext.
		[]string{"go_file_metadata",
			// The context tool returns context for all imports, which can consume a
			// lot of tokens. Conservatively, rely on the model selecting the imports
			// to summarize using the outline tool.
			"go_context",
			// The fileDiagnosticsTool only returns diagnostics for the current file,
			// but often changes will cause breakages in other tools. The
			// workspaceDiagnosticsTool always returns breakages, and supports running
			// deeper diagnostics in selected files.
			"go_file_diagnostics",
			// The references tool requires a location, which models tend to get wrong.
			// The symbolic variant seems to be easier to get right, albeit less
			// powerful.
			"go_references",
		}...)
	var toolConfig map[string]bool // non-default settings
	// For testing, poke through to the gopls server to access its options,
	// and enable some of the disabled tools.
	if hasOpts, ok := lspServer.(interface{ Options() *settings.Options }); ok {
		toolConfig = hasOpts.Options().MCPTools
	}
	var tools []string
	for _, tool := range defaultTools {
		if enabled, ok := toolConfig[tool]; !ok || enabled {
			tools = append(tools, tool)
		}
	}
	// Disabled tools must be explicitly enabled.
	for _, tool := range disabledTools {
		if toolConfig[tool] {
			tools = append(tools, tool)
		}
	}
	for _, tool := range tools {
		addToolByName(mcpServer, h, tool)
	}

	// Subscribe to the roots change.
	if rootsHandler != nil {
		mcpServer.AddReceivingMiddleware(func(next mcp.MethodHandler) mcp.MethodHandler {
			return func(ctx context.Context, method string, req mcp.Request) (mcp.Result, error) {
				result, err := next(ctx, method, req)

				// Read roots list after initialized once and every time roots
				// list changes and pass them to handler.
				//
				// See MCP spec:
				//
				//  The server SHOULD NOT send requests other than pings
				//  and logging before receiving the initialized notification.
				//
				// https://modelcontextprotocol.info/specification/2024-11-05/basic/lifecycle/#initialization
				if method == "notifications/initialized" || method == "notifications/roots/list_changed" {
					go func() {
						var session *mcp.ServerSession
						for s := range mcpServer.Sessions() {
							if s.ID() == req.GetSession().ID() {
								session = s
								break
							}
						}

						if session == nil { // session terminated.
							return
						}

						if session.InitializeParams().Capabilities.RootsV2 == nil {
							return // client does not support roots
						}

						roots, err := session.ListRoots(context.Background(), &mcp.ListRootsParams{})
						rootsHandler(roots, err)
					}()
				}

				return result, err
			}
		})
	}

	return mcpServer
}

func addToolByName(mcpServer *mcp.Server, h handler, name string) {
	switch name {
	case "go_context":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_context",
			Description: "Provide context for a region within a Go file",
		}, h.contextHandler)
	case "go_diagnostics":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name: "go_diagnostics",
			Description: `Provides Go workspace diagnostics.

Checks for parse and build errors across the entire Go workspace. If provided,
"files" holds absolute paths for active files, on which additional linting is
performed.
`,
		}, h.workspaceDiagnosticsHandler)
	case "go_file_context":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_file_context",
			Description: "Summarizes a file's cross-file dependencies",
		}, h.fileContextHandler)
	case "go_file_diagnostics":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_file_diagnostics",
			Description: "Provides diagnostics for a Go file",
		}, h.fileDiagnosticsHandler)
	case "go_file_metadata":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_file_metadata",
			Description: "Provides metadata about the Go package containing the file",
		}, h.fileMetadataHandler)
	case "go_package_api":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_package_api",
			Description: "Provides a summary of a Go package API",
		}, h.outlineHandler)
	case "go_references":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_references",
			Description: "Provide the locations of references to a given object",
		}, h.referencesHandler)
	case "go_rename_symbol":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name: "go_rename_symbol",
			Description: `Renames a symbol in the Go workspace

For example, given arguments {"file": "/path/to/foo.go", "symbol": "Foo", "new_name": "Bar"},
go_rename_symbol returns the edits necessary to rename the symbol "Foo" (located in the file foo.go) to
"Bar" across the Go workspace.`,
		}, h.renameSymbolHandler)
	case "go_search":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name: "go_search",
			Description: `Search for symbols in the Go workspace.

Search for symbols using case-insensitive fuzzy search, which may match all or
part of the fully qualified symbol name. For example, the query 'foo' matches
Go symbols 'Foo', 'fooBar', 'futils.Oboe', 'github.com/foo/bar.Baz'.

Results are limited to 100 symbols.
`,
		}, h.searchHandler)
	case "go_symbol_references":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name: "go_symbol_references",
			Description: `Provides the locations of references to a (possibly qualified)
package-level Go symbol referenced from the current file.

For example, given arguments {"file": "/path/to/foo.go", "name": "Foo"},
go_symbol_references returns references to the symbol "Foo" declared
in the current package.

Similarly, given arguments {"file": "/path/to/foo.go", "name": "lib.Bar"},
go_symbol_references returns references to the symbol "Bar" in the imported lib
package.

Finally, symbol references supporting querying fields and methods: symbol
"T.M" selects the "M" field or method of the "T" type (or value), and "lib.T.M"
does the same for a symbol in the imported package "lib".
`,
		}, h.symbolReferencesHandler)
	case "go_workspace":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name:        "go_workspace",
			Description: "Summarize the Go programming language workspace",
			InputSchema: &jsonschema.Schema{
				Type:       "object",
				Properties: map[string]*jsonschema.Schema{},
			},
		}, h.workspaceHandler)
	case "go_vulncheck":
		mcp.AddTool(mcpServer, &mcp.Tool{
			Name: "go_vulncheck",
			Description: `Runs a vulnerability check on the Go workspace.

	The check is performed on a given package pattern within a specified directory.
	If no directory is provided, it defaults to the workspace root.
	If no pattern is provided, it defaults to "./...".`,
		}, h.vulncheckHandler)
	}
}

// snapshot returns the best default snapshot to use for workspace queries.
func (h *handler) snapshot() (*cache.Snapshot, func(), error) {
	views := h.session.Views()
	if len(views) == 0 {
		return nil, nil, fmt.Errorf("No active builds.")
	}
	return views[0].Snapshot()
}

// fileOf is like [cache.Session.FileOf], but does a sanity check for file
// changes. Currently, it checks for modified files in the transitive closure
// of the file's narrowest package.
//
// This helps avoid stale packages, but is not a substitute for real file
// watching, as it misses things like files being added to a package.
func (h *handler) fileOf(ctx context.Context, file string) (file.Handle, *cache.Snapshot, func(), error) {
	uri := protocol.URIFromPath(file)
	fh, snapshot, release, err := h.session.FileOf(ctx, uri)
	if err != nil {
		return nil, nil, nil, err
	}
	md, err := snapshot.NarrowestMetadataForFile(ctx, uri)
	if err != nil {
		release()
		return nil, nil, nil, err
	}
	fileEvents, err := checkForFileChanges(ctx, snapshot, md.ID)
	if err != nil {
		release()
		return nil, nil, nil, err
	}
	if len(fileEvents) == 0 {
		return fh, snapshot, release, nil
	}
	release() // snapshot is not latest

	// We detect changed files: process them before getting the snapshot.
	if err := h.lspServer.DidChangeWatchedFiles(ctx, &protocol.DidChangeWatchedFilesParams{
		Changes: fileEvents,
	}); err != nil {
		return nil, nil, nil, err
	}
	return h.session.FileOf(ctx, uri)
}

// checkForFileChanges checks for file changes in the transitive closure of
// the given package, by checking file modification time. Since it does not
// actually read file contents, it may miss changes that occur within the mtime
// resolution of the current file system (on some operating systems, this may
// be as much as a second).
//
// It also doesn't catch package changes that occur due to added files or
// changes to the go.mod file.
func checkForFileChanges(ctx context.Context, snapshot *cache.Snapshot, id metadata.PackageID) ([]protocol.FileEvent, error) {
	var events []protocol.FileEvent

	seen := make(map[metadata.PackageID]struct{})
	var checkPkg func(id metadata.PackageID) error
	checkPkg = func(id metadata.PackageID) error {
		if _, ok := seen[id]; ok {
			return nil
		}
		seen[id] = struct{}{}

		mp := snapshot.Metadata(id)
		for _, uri := range mp.CompiledGoFiles {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return err // context cancelled
			}

			mtime, mtimeErr := fh.ModTime()
			fi, err := os.Stat(uri.Path())
			switch {
			case err != nil:
				if mtimeErr == nil {
					// file existed, and doesn't anymore, so the file was deleted
					events = append(events, protocol.FileEvent{URI: uri, Type: protocol.Deleted})
				}
			case mtimeErr != nil:
				// err == nil (from above), so the file was created
				events = append(events, protocol.FileEvent{URI: uri, Type: protocol.Created})
			case !mtime.IsZero() && fi.ModTime().After(mtime):
				events = append(events, protocol.FileEvent{URI: uri, Type: protocol.Changed})
			}
		}
		for _, depID := range mp.DepsByPkgPath {
			if err := checkPkg(depID); err != nil {
				return err
			}
		}
		return nil
	}
	return events, checkPkg(id)
}

func textResult(text string) *mcp.CallToolResult {
	return &mcp.CallToolResult{
		Content: []mcp.Content{&mcp.TextContent{Text: text}},
	}
}


================================================
FILE: gopls/internal/mcp/mcp_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"errors"
	"net/http"
	"testing"
	"time"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	internalmcp "golang.org/x/tools/gopls/internal/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
)

type emptySessions struct {
}

// FirstSession implements mcp.Sessions.
func (e emptySessions) FirstSession() (*cache.Session, protocol.Server) {
	return nil, nil
}

// Session implements mcp.Sessions.
func (e emptySessions) Session(string) (*cache.Session, protocol.Server) {
	return nil, nil
}

// SetSessionExitFunc implements mcp.Sessions.
func (e emptySessions) SetSessionExitFunc(func(string)) {
}

func TestContextCancellation(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())

	res := make(chan error)
	go func() {
		res <- internalmcp.Serve(ctx, "localhost:0", emptySessions{}, true, nil)
	}()

	time.Sleep(1 * time.Second)
	cancel()

	select {
	case err := <-res:
		if !errors.Is(err, http.ErrServerClosed) {
			t.Errorf("mcp server unexpected return got %v, want: %v", err, http.ErrServerClosed)
		}
	case <-time.After(5 * time.Second):
		t.Errorf("mcp server did not terminate after 5 seconds of context cancellation")
	}
}

func TestClientRootChange(t *testing.T) {
	foundError := make(chan error, 1)
	foundAll := []chan struct{}{
		make(chan struct{}), // after initialized
		make(chan struct{}), // after roots/list_changed
	}

	wantRoots := []map[string]struct{}{
		{ // after initialized
			"file:///path/to/one": struct{}{},
			"file:///path/to/two": struct{}{},
		},
		{ // after roots/list_changed
			"file:///path/to/one":   struct{}{},
			"file:///path/to/two":   struct{}{},
			"file:///path/to/three": struct{}{},
			"file:///path/to/four":  struct{}{},
		},
	}

	var callCount int

	server := internalmcp.NewServer(nil, nil, func(res *mcp.ListRootsResult, err error) {
		if err != nil {
			foundError <- err
			return
		}

		if callCount >= len(wantRoots) {
			t.Errorf("Handler called more times than expected: %d", callCount)
			return
		}

		expected := wantRoots[callCount]

		if len(res.Roots) != len(expected) {
			t.Errorf("Phase %d: expected %d roots, got %d", callCount+1, len(expected), len(res.Roots))
			return
		}

		for _, r := range res.Roots {
			if _, ok := expected[r.URI]; !ok {
				t.Errorf("Phase %d: unexpected root %s", callCount+1, r)
			}
		}

		callCount++
		close(foundAll[callCount-1]) // Signal that this phase is complete
	})

	client := mcp.NewClient(&mcp.Implementation{Name: "test-client"}, nil)
	client.AddRoots(&mcp.Root{
		Name: "one",
		URI:  "file:///path/to/one",
	}, &mcp.Root{
		Name: "two",
		URI:  "file:///path/to/two",
	})

	clientTransport, serverTransport := mcp.NewInMemoryTransports()

	ctx := t.Context()

	// Connect server and client
	serverSession, _ := server.Connect(ctx, serverTransport, nil)
	defer serverSession.Close()

	clientSession, _ := client.Connect(ctx, clientTransport, nil)
	defer clientSession.Close()

	// Phase 1: Wait for the initial handshake and first root fetch
	select {
	case <-foundAll[0]:
		t.Log("Phase 1: Initial roots received successfully.")
	case err := <-foundError:
		t.Fatalf("Server handler error during initialization: %v", err)
	case <-time.After(20 * time.Second):
		t.Fatal("Timeout waiting for initial roots.")
	}

	// Trigger the root change
	client.AddRoots(&mcp.Root{
		Name: "three",
		URI:  "file:///path/to/three",
	}, &mcp.Root{
		Name: "four",
		URI:  "file:///path/to/four",
	})

	// Phase 2: Wait for the server to catch the notification and fetch the updated roots
	select {
	case <-foundAll[1]:
		t.Log("Phase 2: Updated roots received successfully.")
	case err := <-foundError:
		t.Fatalf("Server handler error after root change: %v", err)
	case <-time.After(20 * time.Second):
		t.Fatal("Timeout waiting for updated roots.")
	}
}


================================================
FILE: gopls/internal/mcp/outline.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"strconv"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache/metadata"
)

type outlineParams struct {
	PackagePaths []string `json:"packagePaths" jsonschema:"the go package paths to describe"`
}

func (h *handler) outlineHandler(ctx context.Context, req *mcp.CallToolRequest, params outlineParams) (*mcp.CallToolResult, any, error) {
	countGoPackageAPIMCP.Inc()
	snapshot, release, err := h.snapshot()
	if err != nil {
		return nil, nil, err
	}
	defer release()

	// Await initialization to ensure we've at least got an initial package graph
	md, err := snapshot.LoadMetadataGraph(ctx)
	if err != nil {
		return nil, nil, err
	}
	var toSummarize []*metadata.Package
	for _, imp := range params.PackagePaths {
		pkgPath := metadata.PackagePath(imp)
		if len(imp) > 0 && imp[0] == '"' {
			unquoted, err := strconv.Unquote(imp)
			if err != nil {
				return nil, nil, fmt.Errorf("failed to unquote %s: %v", imp, err)
			}
			pkgPath = metadata.PackagePath(unquoted)
		}
		if mps := md.ForPackagePath[pkgPath]; len(mps) > 0 {
			toSummarize = append(toSummarize, mps[0]) // first is best
		}
	}

	var content []mcp.Content
	for _, mp := range toSummarize {
		if md == nil {
			continue // ignore error
		}
		if summary := summarizePackage(ctx, snapshot, mp); summary != "" {
			content = append(content, &mcp.TextContent{Text: summary})
		}
	}
	return &mcp.CallToolResult{
		Content: content,
	}, nil, nil
}


================================================
FILE: gopls/internal/mcp/references.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mcp

import (
	"context"
	"fmt"
	"path/filepath"
	"strings"
	"unicode"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
)

type findReferencesParams struct {
	Location protocol.Location `json:"location"`
}

func (h *handler) referencesHandler(ctx context.Context, req *mcp.CallToolRequest, params findReferencesParams) (*mcp.CallToolResult, any, error) {
	countGoReferencesMCP.Inc()
	fh, snapshot, release, err := h.session.FileOf(ctx, params.Location.URI)
	if err != nil {
		return nil, nil, err
	}
	defer release()
	pos := params.Location.Range.Start
	refs, err := golang.References(ctx, snapshot, fh, protocol.Range{Start: pos, End: pos}, true)
	if err != nil {
		return nil, nil, err
	}
	formatted, err := formatReferences(ctx, snapshot, refs)
	return formatted, nil, err
}

func formatReferences(ctx context.Context, snapshot *cache.Snapshot, refs []protocol.Location) (*mcp.CallToolResult, error) {
	if len(refs) == 0 {
		return nil, fmt.Errorf("no references found")
	}
	var builder strings.Builder
	fmt.Fprintf(&builder, "The object has %v references. Their locations are listed below\n", len(refs))
	for i, r := range refs {
		fmt.Fprintf(&builder, "Reference %d\n", i+1)
		fmt.Fprintf(&builder, "Located in the file: %s\n", filepath.ToSlash(r.URI.Path()))
		refFh, err := snapshot.ReadFile(ctx, r.URI)
		// If for some reason there is an error reading the file content, we should still
		// return the references URIs.
		if err != nil {
			continue
		}
		content, err := refFh.Content()
		if err != nil {
			continue
		}
		lines := strings.Split(string(content), "\n")
		var lineContent string
		if int(r.Range.Start.Line) < len(lines) {
			lineContent = strings.TrimLeftFunc(lines[r.Range.Start.Line], unicode.IsSpace)
		} else {
			continue
		}
		fmt.Fprintf(&builder, "The reference is located on line %v, which has content `%s`\n", r.Range.Start.Line, lineContent)
		builder.WriteString("\n")
	}
	return textResult(builder.String()), nil
}


================================================
FILE: gopls/internal/mcp/rename_symbol.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
)

type renameSymbolParams struct {
	File    string `json:"file" jsonschema:"the absolute path to the file containing the symbol"`
	Symbol  string `json:"symbol" jsonschema:"the symbol or qualified symbol"`
	NewName string `json:"new_name" jsonschema:"the new name for the symbol"`
}

func (h *handler) renameSymbolHandler(ctx context.Context, req *mcp.CallToolRequest, params renameSymbolParams) (*mcp.CallToolResult, any, error) {
	countGoRenameSymbolMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	if snapshot.FileKind(fh) != file.Go {
		return nil, nil, fmt.Errorf("can't rename symbols in non-Go files")
	}
	loc, err := symbolLocation(ctx, snapshot, fh.URI(), params.Symbol)
	if err != nil {
		return nil, nil, err
	}
	changes, err := golang.Rename(ctx, snapshot, fh, loc.Range, params.NewName)
	if err != nil {
		return nil, nil, err
	}
	var builder strings.Builder
	if err := formatRenameChanges(ctx, snapshot, &builder, changes); err != nil {
		return nil, nil, err
	}
	return textResult(builder.String()), nil, nil
}

// formatRenameChanges converts the list of DocumentChange to a unified diff and writes them to the specified buffer.
func formatRenameChanges(ctx context.Context, snapshot *cache.Snapshot, w *strings.Builder, changes []protocol.DocumentChange) error {
	w.WriteString("The following changes are necessary to rename the symbol:\n")
	if err := writeUnifiedDiff(ctx, snapshot, w, changes); err != nil {
		return err
	}
	w.WriteString("\n")
	return nil
}


================================================
FILE: gopls/internal/mcp/search.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
)

type searchParams struct {
	Query string `json:"query" jsonschema:"the fuzzy search query to use for matching symbols"`
}

func (h *handler) searchHandler(ctx context.Context, req *mcp.CallToolRequest, params searchParams) (*mcp.CallToolResult, any, error) {
	countGoSearchMCP.Inc()
	query := params.Query
	if len(query) == 0 {
		return nil, nil, fmt.Errorf("empty query")
	}
	syms, err := h.lspServer.Symbol(ctx, &protocol.WorkspaceSymbolParams{
		Query: params.Query,
	})
	if err != nil {
		return nil, nil, fmt.Errorf("failed to execute symbol query: %v", err)
	}
	if len(syms) == 0 {
		return textResult("No symbols found."), nil, nil
	}
	var b strings.Builder
	fmt.Fprintf(&b, "Top symbol matches:\n")
	for _, sym := range syms {
		fmt.Fprintf(&b, "\t%s (%s in `%s`)\n", sym.Name, kindName(sym.Kind), sym.Location.URI.Path())
	}
	return textResult(b.String()), nil, nil
}

// kindName returns the adjusted name for the given symbol kind,
// fixing LSP conventions that don't work for go, like 'Class'.
func kindName(k protocol.SymbolKind) string {
	if k == protocol.Class {
		return "Type"
	}
	return fmt.Sprint(k)
}


================================================
FILE: gopls/internal/mcp/symbol_references.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mcp

import (
	"context"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
)

// symbolReferencesParams defines the parameters for the "go_symbol_references"
// tool.
type symbolReferencesParams struct {
	File   string `json:"file" jsonschema:"the absolute path to the file containing the symbol"`
	Symbol string `json:"symbol" jsonschema:"the symbol or qualified symbol"`
}

// symbolReferencesHandler is the handler for the "go_symbol_references" tool.
// It finds all references to the requested symbol and describes their
// locations.
func (h *handler) symbolReferencesHandler(ctx context.Context, req *mcp.CallToolRequest, params symbolReferencesParams) (*mcp.CallToolResult, any, error) {
	countGoSymbolReferencesMCP.Inc()
	fh, snapshot, release, err := h.fileOf(ctx, params.File)
	if err != nil {
		return nil, nil, err
	}
	defer release()

	if snapshot.FileKind(fh) != file.Go {
		return nil, nil, fmt.Errorf("can't provide references for non-Go files")
	}

	loc, err := symbolLocation(ctx, snapshot, fh.URI(), params.Symbol)
	if err != nil {
		return nil, nil, err
	}
	declFH, err := snapshot.ReadFile(ctx, loc.URI)
	if err != nil {
		return nil, nil, err
	}
	refs, err := golang.References(ctx, snapshot, declFH, loc.Range, true)
	if err != nil {
		return nil, nil, err
	}
	formatted, err := formatReferences(ctx, snapshot, refs)
	return formatted, nil, err
}

// symbolLocation returns the protocol.Location of the given symbol within the file uri, or an error if it cannot be located.
func symbolLocation(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, symbol string) (protocol.Location, error) {
	// Parse and extract names before type checking, to fail fast in the case of
	// invalid inputs.
	e, err := parser.ParseExpr(symbol)
	if err != nil {
		return protocol.Location{}, fmt.Errorf("\"symbol\" failed to parse: %v", err)
	}
	path, err := extractPath(e)
	if err != nil {
		return protocol.Location{}, err
	}

	pkg, pgf, err := golang.NarrowestPackageForFile(ctx, snapshot, uri)
	if err != nil {
		return protocol.Location{}, err
	}

	target, err := resolveSymbol(path, pkg, pgf)
	if err != nil {
		return protocol.Location{}, err
	}

	loc, err := golang.ObjectLocation(ctx, pkg.FileSet(), snapshot, target)
	if err != nil {
		return protocol.Location{}, fmt.Errorf("finding symbol location: %v", err)
	}
	return loc, nil
}

// extractPath extracts the 'path' of names from e, which must be of the form
// a, a.b, or a.b.c.
//
// If a nil error is returned, the resulting path is either length 1, 2, or 3.
func extractPath(e ast.Expr) ([]string, error) {
	switch e := e.(type) {
	case *ast.Ident:
		return []string{e.Name}, nil
	case *ast.SelectorExpr:
		switch x := e.X.(type) {
		case *ast.Ident:
			// Qualified identifier 'a.b', where a is a package or receiver.
			return []string{x.Name, e.Sel.Name}, nil
		case *ast.SelectorExpr:
			// Imported field or method a.b.c: a must be a package name.
			if x2, ok := x.X.(*ast.Ident); ok {
				return []string{x2.Name, x.Sel.Name, e.Sel.Name}, nil
			}
		}
	}
	return nil, fmt.Errorf("invalid qualified symbol: expected a.b or a.b.c")
}

// resolveSymbol resolves the types.Object for the given qualified path, which
// must be of length 1, 2, or 3:
//   - For length 1 paths, the symbol is a name in the file scope.
//   - For length 2 paths, the symbol is either field, method, or imported symbol.
//   - For length 3 paths, the symbol is a field or method on an important object.
func resolveSymbol(path []string, pkg *cache.Package, pgf *parsego.File) (types.Object, error) {
	fileScope, ok := pkg.TypesInfo().Scopes[pgf.File]
	if !ok {
		return nil, fmt.Errorf("internal error: no scope for file")
	}

	switch len(path) {
	case 1:
		_, target := fileScope.LookupParent(path[0], token.NoPos)
		if target == nil {
			return nil, fmt.Errorf("failed to resolve name %q", path[0])
		}
		return target, nil
	case 2:
		switch _, obj := fileScope.LookupParent(path[0], token.NoPos); obj := obj.(type) {
		case *types.PkgName:
			target := obj.Imported().Scope().Lookup(path[1])
			if target == nil {
				return nil, fmt.Errorf("failed to resolve member %q of %q", path[1], path[0])
			}
			return target, nil
		case nil:
			return nil, fmt.Errorf("failed to resolve name %q", path[0])
		default:
			target, _, _ := types.LookupFieldOrMethod(obj.Type(), true, pkg.Types(), path[1])
			if target == nil {
				return nil, fmt.Errorf("failed to resolve member %q of %q", path[1], path[0])
			}
			return target, nil
		}
	case 3:
		// Imported field or method a.b.c: a must be a package name.
		obj := fileScope.Lookup(path[0])
		p, ok := obj.(*types.PkgName)
		if !ok {
			return nil, fmt.Errorf("invalid qualified symbol: %q must be a package (got %T)", path[0], obj)
		}
		recv := p.Imported().Scope().Lookup(path[1])
		if recv == nil {
			return nil, fmt.Errorf("invalid qualified symbol: could not find %q in package %q", path[1], path[0])
		}
		target, _, _ := types.LookupFieldOrMethod(recv.Type(), true, pkg.Types(), path[2])
		if target == nil {
			return nil, fmt.Errorf("failed to resolve member %q of %q", path[2], path[1])
		}
		return target, nil
	}
	panic("unreachable")
}


================================================
FILE: gopls/internal/mcp/vulncheck.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"fmt"
	"maps"
	"slices"
	"sort"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/vulncheck/scan"
)

type vulncheckParams struct {
	Dir     string `json:"dir,omitempty" jsonschema:"directory to run the vulnerability check within"`
	Pattern string `json:"pattern,omitempty" jsonschema:"package pattern to check"`
}

type GroupedVulnFinding struct {
	ID               string   `json:"id"`
	Details          string   `json:"details"`
	AffectedPackages []string `json:"affectedPackages"`
}

type VulncheckResultOutput struct {
	Findings []GroupedVulnFinding `json:"findings,omitempty"`
	Logs     string               `json:"logs,omitempty"`
}

func (h *handler) vulncheckHandler(ctx context.Context, req *mcp.CallToolRequest, params *vulncheckParams) (*mcp.CallToolResult, *VulncheckResultOutput, error) {
	countGoVulncheckMCP.Inc()
	snapshot, release, err := h.snapshot()
	if err != nil {
		return nil, nil, err
	}
	defer release()

	dir := params.Dir
	if dir == "" && len(h.session.Views()) > 0 {
		dir = h.session.Views()[0].Root().Path()
	}

	pattern := params.Pattern
	if pattern == "" {
		pattern = "./..."
	}

	var logBuf bytes.Buffer
	result, err := scan.RunGovulncheck(ctx, pattern, snapshot, dir, &logBuf)
	if err != nil {
		return nil, nil, fmt.Errorf("running govulncheck failed: %v\nLogs:\n%s", err, logBuf.String())
	}

	groupedPkgs := make(map[string]map[string]struct{})
	for _, finding := range result.Findings {
		if osv := result.Entries[finding.OSV]; osv != nil {
			if _, ok := groupedPkgs[osv.ID]; !ok {
				groupedPkgs[osv.ID] = make(map[string]struct{})
			}
			pkg := finding.Trace[0].Package
			if pkg == "" {
				pkg = "Go standard library"
			}
			groupedPkgs[osv.ID][pkg] = struct{}{}
		}
	}

	var output VulncheckResultOutput
	if len(groupedPkgs) > 0 {
		output.Findings = make([]GroupedVulnFinding, 0, len(groupedPkgs))
		for id, pkgsSet := range groupedPkgs {
			pkgs := slices.Sorted(maps.Keys(pkgsSet))

			output.Findings = append(output.Findings, GroupedVulnFinding{
				ID:               id,
				Details:          result.Entries[id].Details,
				AffectedPackages: pkgs,
			})
		}
		sort.Slice(output.Findings, func(i, j int) bool {
			return output.Findings[i].ID < output.Findings[j].ID
		})
	}

	if logBuf.Len() > 0 {
		output.Logs = logBuf.String()
	}

	var summary bytes.Buffer
	fmt.Fprintf(&summary, "Vulnerability check for pattern %q complete. Found %d vulnerabilities.", pattern, len(output.Findings))
	if output.Logs != "" {
		fmt.Fprintf(&summary, "\nLogs are available in the structured output.")
	}

	return nil, &output, nil
}


================================================
FILE: gopls/internal/mcp/workspace.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"strings"

	"slices"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/immutable"
)

func (h *handler) workspaceHandler(ctx context.Context, req *mcp.CallToolRequest, _ any) (*mcp.CallToolResult, any, error) {
	countGoWorkspaceMCP.Inc()
	var summary bytes.Buffer
	views := h.session.Views()
	for _, v := range views {
		snapshot, release, err := v.Snapshot()
		if err != nil {
			continue // view is shut down
		}
		defer release()

		pkgs := snapshot.WorkspacePackages()

		// Special case: check if it's likely that this isn't actually a Go workspace.
		if len(views) == 1 && // only view
			(v.Type() == cache.AdHocView || v.Type() == cache.GoPackagesDriverView) && // not necessarily Go code
			pkgs.Len() == 0 { // no packages

			return &mcp.CallToolResult{
				Content: []mcp.Content{&mcp.TextContent{Text: "This is not a Go workspace. To work on Go code, open a directory inside a Go module."}},
			}, nil, nil
		}

		dir := v.Root().Path()
		switch v.Type() {
		case cache.GoPackagesDriverView:
			fmt.Fprintf(&summary, "The `%s` directory is loaded using a custom golang.org/x/tools/go/packages driver.\n", dir)
			fmt.Fprintf(&summary, "This indicates a non-standard build system.\n")

		case cache.GOPATHView:
			fmt.Fprintf(&summary, "The `%s` directory is loaded using a the legacy GOPATH build system.\n", dir)

		case cache.GoModView:
			fmt.Fprintf(&summary, "The `%s` directory uses Go modules, with the following main modules:\n", dir)
			summarizeModFiles(ctx, &summary, snapshot)

		case cache.GoWorkView:
			fmt.Fprintf(&summary, "The `%s` directory is in the go workspace defined by `%s`, with the following main modules:\n", dir, v.GoWork().Path())
			summarizeModFiles(ctx, &summary, snapshot)

		case cache.AdHocView:
			fmt.Fprintf(&summary, "The `%s` directory is an ad-hoc Go package, not in a Go module.\n", dir)
		}
		fmt.Fprintln(&summary)
		const summarizePackages = false
		if summarizePackages {
			summaries := packageSummaries(snapshot, pkgs)
			fmt.Fprintf(&summary, "It contains the following Go packages:\n")
			fmt.Fprintf(&summary, "\t%s\n", strings.Join(summaries, "\n\t"))
			fmt.Fprintln(&summary)
		}
	}
	return textResult(summary.String()), nil, nil
}

func summarizeModFiles(ctx context.Context, w io.Writer, snapshot *cache.Snapshot) {
	v := snapshot.View()
	for _, m := range v.ModFiles() {
		if modPath, err := modulePath(ctx, snapshot, m); err != nil {
			// Fall back on just the go.mod file.
			fmt.Fprintf(w, "\t%s\n", m.Path())
		} else {
			fmt.Fprintf(w, "\t%s (module %s)\n", m.Path(), modPath)
		}
	}
}

func modulePath(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) (string, error) {
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return "", fmt.Errorf("Reading %s: %v", uri, err)
	}
	pmf, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return "", fmt.Errorf("parsing modfile: %v", err)
	}
	if pmf.File == nil || pmf.File.Module == nil {
		return "", fmt.Errorf("malformed modfile")
	}
	return pmf.File.Module.Mod.Path, nil
}

func packageSummaries(snapshot *cache.Snapshot, pkgs immutable.Map[cache.PackageID, cache.PackagePath]) []string {
	var summaries []string
	for id := range pkgs.All() {
		mp := snapshot.Metadata(id)
		if len(mp.CompiledGoFiles) == 0 {
			continue // For convenience, just skip uncompiled packages; we could do more if it matters.
		}
		dir := mp.CompiledGoFiles[0].DirPath()
		summaries = append(summaries, fmt.Sprintf("The `%s` directory contains the %q package with path %q", dir, mp.Name, mp.PkgPath))
	}
	slices.Sort(summaries) // for stability
	return summaries
}


================================================
FILE: gopls/internal/mcp/workspace_diagnostics.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"maps"
	"slices"
	"strings"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

type workspaceDiagnosticsParams struct {
	Files []string `json:"files,omitempty" jsonschema:"absolute paths to active files, if any"`
}

func (h *handler) workspaceDiagnosticsHandler(ctx context.Context, req *mcp.CallToolRequest, params workspaceDiagnosticsParams) (*mcp.CallToolResult, any, error) {
	countGoDiagnosticsMCP.Inc()
	var (
		fh       file.Handle
		snapshot *cache.Snapshot
		release  func()
		err      error
	)
	if len(params.Files) > 0 {
		fh, snapshot, release, err = h.fileOf(ctx, params.Files[0])
		if err != nil {
			return nil, nil, err
		}
	} else {
		views := h.session.Views()
		if len(views) == 0 {
			return nil, nil, fmt.Errorf("No active builds.")
		}
		snapshot, release, err = views[0].Snapshot()
		if err != nil {
			return nil, nil, err
		}
	}
	defer release()

	pkgMap := snapshot.WorkspacePackages()
	var ids []metadata.PackageID
	for id := range pkgMap.All() {
		ids = append(ids, id)
	}
	slices.Sort(ids)

	diagnostics, err := snapshot.PackageDiagnostics(ctx, ids...)
	if err != nil {
		return nil, nil, fmt.Errorf("diagnostics failed: %v", err)
	}

	fixes := make(map[*cache.Diagnostic]*protocol.CodeAction)
	for _, file := range params.Files {
		uri := protocol.URIFromPath(file)
		// Get more specific diagnostics for the file in question.
		fileDiagnostics, fileFixes, err := h.diagnoseFile(ctx, snapshot, uri)
		if err != nil {
			return nil, nil, fmt.Errorf("diagnostics failed: %v", err)
		}
		diagnostics[fh.URI()] = fileDiagnostics
		maps.Insert(fixes, maps.All(fileFixes))
	}

	keys := slices.Sorted(maps.Keys(diagnostics))
	var b strings.Builder
	for _, uri := range keys {
		diags := diagnostics[uri]
		if len(diags) > 0 {
			fmt.Fprintf(&b, "File `%s` has the following diagnostics:\n", uri.Path())
			if err := summarizeDiagnostics(ctx, snapshot, &b, diags, fixes); err != nil {
				return nil, nil, err
			}
			fmt.Fprintln(&b)
		}
	}

	if b.Len() == 0 {
		return textResult("No diagnostics."), nil, nil
	}

	return textResult(b.String()), nil, nil
}


================================================
FILE: gopls/internal/mod/code_lens.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mod

import (
	"context"
	"fmt"
	"os"
	"path/filepath"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
)

// CodeLensSources returns the sources of code lenses for go.mod files.
func CodeLensSources() map[settings.CodeLensSource]cache.CodeLensSourceFunc {
	return map[settings.CodeLensSource]cache.CodeLensSourceFunc{
		settings.CodeLensUpgradeDependency: upgradeLenses,        // commands: CheckUpgrades, UpgradeDependency
		settings.CodeLensTidy:              tidyLens,             // commands: Tidy
		settings.CodeLensVendor:            vendorLens,           // commands: Vendor
		settings.CodeLensVulncheck:         vulncheckLenses,      // commands: Vulncheck
		settings.CodeLensRunGovulncheck:    runGovulncheckLenses, // commands: RunGovulncheck
	}
}

func upgradeLenses(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil || pm.File == nil {
		return nil, err
	}
	uri := fh.URI()
	reset := command.NewResetGoModDiagnosticsCommand("Reset go.mod diagnostics", command.ResetGoModDiagnosticsArgs{URIArg: command.URIArg{URI: uri}})
	// Put the `Reset go.mod diagnostics` codelens on the module statement.
	modrng, err := moduleStmtRange(fh, pm)
	if err != nil {
		return nil, err
	}
	lenses := []protocol.CodeLens{{Range: modrng, Command: reset}}
	if len(pm.File.Require) == 0 {
		// Nothing to upgrade.
		return lenses, nil
	}
	var requires []string
	for _, req := range pm.File.Require {
		requires = append(requires, req.Mod.Path)
	}
	checkUpgrade := command.NewCheckUpgradesCommand("Check for upgrades", command.CheckUpgradesArgs{
		URI:     uri,
		Modules: requires,
	})
	upgradeTransitive := command.NewUpgradeDependencyCommand("Upgrade transitive dependencies", command.DependencyArgs{
		URI:        uri,
		AddRequire: false,
		GoCmdArgs:  []string{"-d", "-u", "-t", "./..."},
	})
	upgradeDirect := command.NewUpgradeDependencyCommand("Upgrade direct dependencies", command.DependencyArgs{
		URI:        uri,
		AddRequire: false,
		GoCmdArgs:  append([]string{"-d"}, requires...),
	})

	// Put the upgrade code lenses above the first require block or statement.
	rng, err := firstRequireRange(fh, pm)
	if err != nil {
		return nil, err
	}

	return append(lenses, []protocol.CodeLens{
		{Range: rng, Command: checkUpgrade},
		{Range: rng, Command: upgradeTransitive},
		{Range: rng, Command: upgradeDirect},
	}...), nil
}

func tidyLens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil || pm.File == nil {
		return nil, err
	}
	uri := fh.URI()
	cmd := command.NewTidyCommand("Run go mod tidy", command.URIArgs{URIs: []protocol.DocumentURI{uri}})
	rng, err := moduleStmtRange(fh, pm)
	if err != nil {
		return nil, err
	}
	return []protocol.CodeLens{{
		Range:   rng,
		Command: cmd,
	}}, nil
}

func vendorLens(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil || pm.File == nil {
		return nil, err
	}
	if len(pm.File.Require) == 0 {
		// Nothing to vendor.
		return nil, nil
	}
	rng, err := moduleStmtRange(fh, pm)
	if err != nil {
		return nil, err
	}
	title := "Create vendor directory"
	uri := fh.URI()
	cmd := command.NewVendorCommand(title, command.URIArg{URI: uri})
	// Change the message depending on whether or not the module already has a
	// vendor directory.
	vendorDir := filepath.Join(fh.URI().DirPath(), "vendor")
	if info, _ := os.Stat(vendorDir); info != nil && info.IsDir() {
		title = "Sync vendor directory"
	}
	return []protocol.CodeLens{{Range: rng, Command: cmd}}, nil
}

func moduleStmtRange(fh file.Handle, pm *cache.ParsedModule) (protocol.Range, error) {
	if pm.File == nil || pm.File.Module == nil || pm.File.Module.Syntax == nil {
		return protocol.Range{}, fmt.Errorf("no module statement in %s", fh.URI())
	}
	syntax := pm.File.Module.Syntax
	return pm.Mapper.OffsetRange(syntax.Start.Byte, syntax.End.Byte)
}

// firstRequireRange returns the range for the first "require" in the given
// go.mod file. This is either a require block or an individual require line.
func firstRequireRange(fh file.Handle, pm *cache.ParsedModule) (protocol.Range, error) {
	if len(pm.File.Require) == 0 {
		return protocol.Range{}, fmt.Errorf("no requires in the file %s", fh.URI())
	}
	var start, end modfile.Position
	for _, stmt := range pm.File.Syntax.Stmt {
		if b, ok := stmt.(*modfile.LineBlock); ok && len(b.Token) == 1 && b.Token[0] == "require" {
			start, end = b.Span()
			break
		}
	}

	firstRequire := pm.File.Require[0].Syntax
	if start.Byte == 0 || firstRequire.Start.Byte < start.Byte {
		start, end = firstRequire.Start, firstRequire.End
	}
	return pm.Mapper.OffsetRange(start.Byte, end.Byte)
}

func vulncheckLenses(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil || pm.File == nil {
		return nil, err
	}
	// Place the codelenses near the module statement.
	// A module may not have the require block,
	// but vulnerabilities can exist in standard libraries.
	uri := fh.URI()
	rng, err := moduleStmtRange(fh, pm)
	if err != nil {
		return nil, err
	}

	vulncheck := command.NewVulncheckCommand("Run govulncheck", command.VulncheckArgs{
		URI:     uri,
		Pattern: "./...",
	})
	return []protocol.CodeLens{
		{Range: rng, Command: vulncheck},
	}, nil
}

func runGovulncheckLenses(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.CodeLens, error) {
	// If CodeLensVulncheck is enabled, do not use the legacy CodeLensRunGovulncheck.
	if snapshot.Options().UserOptions.UIOptions.Codelenses[settings.CodeLensVulncheck] {
		return nil, nil
	}

	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil || pm.File == nil {
		return nil, err
	}
	// Place the codelenses near the module statement.
	// A module may not have the require block,
	// but vulnerabilities can exist in standard libraries.
	uri := fh.URI()
	rng, err := moduleStmtRange(fh, pm)
	if err != nil {
		return nil, err
	}

	vulncheck := command.NewRunGovulncheckCommand("Run govulncheck", command.VulncheckArgs{
		URI:     uri,
		Pattern: "./...",
	})
	return []protocol.CodeLens{
		{Range: rng, Command: vulncheck},
	}, nil
}


================================================
FILE: gopls/internal/mod/diagnostics.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package mod provides core features related to go.mod file
// handling for use by Go editors and tools.
package mod

import (
	"context"
	"fmt"
	"runtime"
	"sort"
	"strings"
	"sync"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/semver"
	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/internal/event"
)

// ParseDiagnostics returns diagnostics from parsing the go.mod files in the workspace.
func ParseDiagnostics(ctx context.Context, snapshot *cache.Snapshot) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	ctx, done := event.Start(ctx, "mod.Diagnostics", snapshot.Labels()...)
	defer done()

	return collectDiagnostics(ctx, snapshot, parseDiagnostics)
}

// TidyDiagnostics returns diagnostics from running go mod tidy.
func TidyDiagnostics(ctx context.Context, snapshot *cache.Snapshot) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	ctx, done := event.Start(ctx, "mod.Diagnostics", snapshot.Labels()...)
	defer done()

	return collectDiagnostics(ctx, snapshot, tidyDiagnostics)
}

// UpgradeDiagnostics returns upgrade diagnostics for the modules in the
// workspace with known upgrades.
func UpgradeDiagnostics(ctx context.Context, snapshot *cache.Snapshot) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	ctx, done := event.Start(ctx, "mod.UpgradeDiagnostics", snapshot.Labels()...)
	defer done()

	return collectDiagnostics(ctx, snapshot, upgradeDiagnostics)
}

// VulnerabilityDiagnostics returns vulnerability diagnostics for the active modules in the
// workspace with known vulnerabilities.
func VulnerabilityDiagnostics(ctx context.Context, snapshot *cache.Snapshot) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	ctx, done := event.Start(ctx, "mod.VulnerabilityDiagnostics", snapshot.Labels()...)
	defer done()

	return collectDiagnostics(ctx, snapshot, vulnerabilityDiagnostics)
}

func collectDiagnostics(ctx context.Context, snapshot *cache.Snapshot, diagFn func(context.Context, *cache.Snapshot, file.Handle) ([]*cache.Diagnostic, error)) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	g, ctx := errgroup.WithContext(ctx)
	cpulimit := runtime.GOMAXPROCS(0)
	g.SetLimit(cpulimit)

	var mu sync.Mutex
	reports := make(map[protocol.DocumentURI][]*cache.Diagnostic)

	for _, uri := range snapshot.View().ModFiles() {
		g.Go(func() error {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return err
			}
			diagnostics, err := diagFn(ctx, snapshot, fh)
			if err != nil {
				return err
			}
			for _, d := range diagnostics {
				mu.Lock()
				reports[d.URI] = append(reports[fh.URI()], d)
				mu.Unlock()
			}
			return nil
		})
	}

	if err := g.Wait(); err != nil {
		return nil, err
	}
	return reports, nil
}

// parseDiagnostics reports diagnostics from parsing the mod file.
func parseDiagnostics(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) (diagnostics []*cache.Diagnostic, err error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		if pm == nil || len(pm.ParseErrors) == 0 {
			return nil, err
		}
		return pm.ParseErrors, nil
	}
	return nil, nil
}

// tidyDiagnostics reports diagnostics from running go mod tidy.
func tidyDiagnostics(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]*cache.Diagnostic, error) {
	pm, err := snapshot.ParseMod(ctx, fh) // memoized
	if err != nil {
		return nil, nil // errors reported by ModDiagnostics above
	}

	tidied, err := snapshot.ModTidy(ctx, pm)
	if err != nil {
		if err != cache.ErrNoModOnDisk && !strings.Contains(err.Error(), "GOPROXY=off") {
			// TODO(rfindley): the check for ErrNoModOnDisk was historically determined
			// to be benign, but may date back to the time when the Go command did not
			// have overlay support.
			//
			// See if we can pass the overlay to the Go command, and eliminate this guard..

			// TODO(golang/go#56395): remove the arbitrary suppression of the mod
			// tidy error when GOPROXY=off. The true fix for this noisy log message
			// is to fix the mod tidy diagnostics.
			event.Error(ctx, fmt.Sprintf("tidy: diagnosing %s", pm.URI), err)
		}
		return nil, nil
	}
	return tidied.Diagnostics, nil
}

// upgradeDiagnostics adds upgrade quick fixes for individual modules if the upgrades
// are recorded in the view.
func upgradeDiagnostics(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) (upgradeDiagnostics []*cache.Diagnostic, err error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		// Don't return an error if there are parse error diagnostics to be shown, but also do not
		// continue since we won't be able to show the upgrade diagnostics.
		if pm != nil && len(pm.ParseErrors) != 0 {
			return nil, nil
		}
		return nil, err
	}

	upgrades := snapshot.ModuleUpgrades(fh.URI())
	for _, req := range pm.File.Require {
		ver, ok := upgrades[req.Mod.Path]
		if !ok || req.Mod.Version == ver {
			continue
		}
		rng, err := pm.Mapper.OffsetRange(req.Syntax.Start.Byte, req.Syntax.End.Byte)
		if err != nil {
			return nil, err
		}
		// Upgrade to the exact version we offer the user, not the most recent.
		title := fmt.Sprintf("%s%v", upgradeCodeActionPrefix, ver)
		cmd := command.NewUpgradeDependencyCommand(title, command.DependencyArgs{
			URI:        fh.URI(),
			AddRequire: false,
			GoCmdArgs:  []string{req.Mod.Path + "@" + ver},
		})
		upgradeDiagnostics = append(upgradeDiagnostics, &cache.Diagnostic{
			URI:            fh.URI(),
			Range:          rng,
			Severity:       protocol.SeverityInformation,
			Source:         cache.UpgradeNotification,
			Message:        fmt.Sprintf("%v can be upgraded", req.Mod.Path),
			SuggestedFixes: []cache.SuggestedFix{cache.SuggestedFixFromCommand(cmd, protocol.QuickFix)},
		})
	}

	return upgradeDiagnostics, nil
}

const upgradeCodeActionPrefix = "Upgrade to "

// vulnerabilityDiagnostics adds diagnostics for vulnerabilities in individual modules
// if the vulnerability is recorded in the view.
func vulnerabilityDiagnostics(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) (vulnDiagnostics []*cache.Diagnostic, err error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		// Don't return an error if there are parse error diagnostics to be shown, but also do not
		// continue since we won't be able to show the vulnerability diagnostics.
		if pm != nil && len(pm.ParseErrors) != 0 {
			return nil, nil
		}
		return nil, err
	}

	diagSource := cache.Govulncheck
	vs := snapshot.Vulnerabilities(fh.URI())[fh.URI()]
	if vs == nil && snapshot.Options().Vulncheck == settings.ModeVulncheckImports {
		vs, err = snapshot.ModVuln(ctx, fh.URI())
		if err != nil {
			return nil, err
		}
		diagSource = cache.Vulncheck
	}
	if vs == nil || len(vs.Findings) == 0 {
		return nil, nil
	}

	suggestRunOrResetGovulncheck, err := suggestGovulncheckAction(diagSource == cache.Govulncheck, fh.URI())
	if err != nil {
		// must not happen
		return nil, err // TODO: bug report
	}
	vulnsByModule := make(map[string][]*govulncheck.Finding)

	for _, finding := range vs.Findings {
		if vuln, typ := foundVuln(finding); typ == vulnCalled || typ == vulnImported {
			vulnsByModule[vuln.Module] = append(vulnsByModule[vuln.Module], finding)
		}
	}
	for _, req := range pm.File.Require {
		mod := req.Mod.Path
		findings := vulnsByModule[mod]
		if len(findings) == 0 {
			continue
		}
		// note: req.Syntax is the line corresponding to 'require', which means
		// req.Syntax.Start can point to the beginning of the "require" keyword
		// for a single line require (e.g. "require golang.org/x/mod v0.0.0").
		start := req.Syntax.Start.Byte
		if len(req.Syntax.Token) == 3 {
			start += len("require ")
		}
		rng, err := pm.Mapper.OffsetRange(start, req.Syntax.End.Byte)
		if err != nil {
			return nil, err
		}
		// Map affecting vulns to 'warning' level diagnostics,
		// others to 'info' level diagnostics.
		// Fixes will include only the upgrades for warning level diagnostics.
		var warningFixes, infoFixes []cache.SuggestedFix
		var warningSet, infoSet = map[string]bool{}, map[string]bool{}
		for _, finding := range findings {
			// It is possible that the source code was changed since the last
			// govulncheck run and information in the `vulns` info is stale.
			// For example, imagine that a user is in the middle of updating
			// problematic modules detected by the govulncheck run by applying
			// quick fixes. Stale diagnostics can be confusing and prevent the
			// user from quickly locating the next module to fix.
			// Ideally we should rerun the analysis with the updated module
			// dependencies or any other code changes, but we are not yet
			// in the position of automatically triggering the analysis
			// (govulncheck can take a while). We also don't know exactly what
			// part of source code was changed since `vulns` was computed.
			// As a heuristic, we assume that a user upgrades the affecting
			// module to the version with the fix or the latest one, and if the
			// version in the require statement is equal to or higher than the
			// fixed version, skip generating a diagnostic about the vulnerability.
			// Eventually, the user has to rerun govulncheck.
			if finding.FixedVersion != "" && semver.IsValid(req.Mod.Version) && semver.Compare(finding.FixedVersion, req.Mod.Version) <= 0 {
				continue
			}
			switch _, typ := foundVuln(finding); typ {
			case vulnImported:
				infoSet[finding.OSV] = true
			case vulnCalled:
				warningSet[finding.OSV] = true
			}
			// Upgrade to the exact version we offer the user, not the most recent.
			if fixedVersion := finding.FixedVersion; semver.IsValid(fixedVersion) && semver.Compare(req.Mod.Version, fixedVersion) < 0 {
				cmd := getUpgradeCodeAction(fh, req, fixedVersion)
				sf := cache.SuggestedFixFromCommand(cmd, protocol.QuickFix)
				switch _, typ := foundVuln(finding); typ {
				case vulnImported:
					infoFixes = append(infoFixes, sf)
				case vulnCalled:
					warningFixes = append(warningFixes, sf)
				}
			}
		}

		if len(warningSet) == 0 && len(infoSet) == 0 {
			continue
		}
		// Remove affecting osvs from the non-affecting osv list if any.
		if len(warningSet) > 0 {
			for k := range infoSet {
				if warningSet[k] {
					delete(infoSet, k)
				}
			}
		}
		// Add an upgrade for module@latest.
		// TODO(suzmue): verify if latest is the same as fixedVersion.
		latest := getUpgradeCodeAction(fh, req, "latest")
		sf := cache.SuggestedFixFromCommand(latest, protocol.QuickFix)
		if len(warningFixes) > 0 {
			warningFixes = append(warningFixes, sf)
		}
		if len(infoFixes) > 0 {
			infoFixes = append(infoFixes, sf)
		}
		if len(warningSet) > 0 {
			warning := sortedKeys(warningSet)
			warningFixes = append(warningFixes, suggestRunOrResetGovulncheck)
			vulnDiagnostics = append(vulnDiagnostics, &cache.Diagnostic{
				URI:            fh.URI(),
				Range:          rng,
				Severity:       protocol.SeverityWarning,
				Source:         diagSource,
				Message:        getVulnMessage(req.Mod.Path, warning, true, diagSource == cache.Govulncheck),
				SuggestedFixes: warningFixes,
			})
		}
		if len(infoSet) > 0 {
			info := sortedKeys(infoSet)
			infoFixes = append(infoFixes, suggestRunOrResetGovulncheck)
			vulnDiagnostics = append(vulnDiagnostics, &cache.Diagnostic{
				URI:            fh.URI(),
				Range:          rng,
				Severity:       protocol.SeverityInformation,
				Source:         diagSource,
				Message:        getVulnMessage(req.Mod.Path, info, false, diagSource == cache.Govulncheck),
				SuggestedFixes: infoFixes,
			})
		}
	}

	// TODO(hyangah): place this diagnostic on the `go` directive or `toolchain` directive
	// after https://go.dev/issue/57001.
	const diagnoseStdLib = false

	// If diagnosing the stdlib, add standard library vulnerability diagnostics
	// on the module declaration.
	//
	// Only proceed if we have a valid module declaration on which to position
	// the diagnostics.
	if diagnoseStdLib && pm.File.Module != nil && pm.File.Module.Syntax != nil {
		// Add standard library vulnerabilities.
		stdlibVulns := vulnsByModule["stdlib"]
		if len(stdlibVulns) == 0 {
			return vulnDiagnostics, nil
		}

		// Put the standard library diagnostic on the module declaration.
		rng, err := pm.Mapper.OffsetRange(pm.File.Module.Syntax.Start.Byte, pm.File.Module.Syntax.End.Byte)
		if err != nil {
			return vulnDiagnostics, nil // TODO: bug report
		}

		var warningSet, infoSet = map[string]bool{}, map[string]bool{}
		for _, finding := range stdlibVulns {
			switch _, typ := foundVuln(finding); typ {
			case vulnImported:
				infoSet[finding.OSV] = true
			case vulnCalled:
				warningSet[finding.OSV] = true
			}
		}
		if len(warningSet) > 0 {
			warning := sortedKeys(warningSet)
			fixes := []cache.SuggestedFix{suggestRunOrResetGovulncheck}
			vulnDiagnostics = append(vulnDiagnostics, &cache.Diagnostic{
				URI:            fh.URI(),
				Range:          rng,
				Severity:       protocol.SeverityWarning,
				Source:         diagSource,
				Message:        getVulnMessage("go", warning, true, diagSource == cache.Govulncheck),
				SuggestedFixes: fixes,
			})

			// remove affecting osvs from the non-affecting osv list if any.
			for k := range infoSet {
				if warningSet[k] {
					delete(infoSet, k)
				}
			}
		}
		if len(infoSet) > 0 {
			info := sortedKeys(infoSet)
			fixes := []cache.SuggestedFix{suggestRunOrResetGovulncheck}
			vulnDiagnostics = append(vulnDiagnostics, &cache.Diagnostic{
				URI:            fh.URI(),
				Range:          rng,
				Severity:       protocol.SeverityInformation,
				Source:         diagSource,
				Message:        getVulnMessage("go", info, false, diagSource == cache.Govulncheck),
				SuggestedFixes: fixes,
			})
		}
	}

	return vulnDiagnostics, nil
}

type vulnFindingType int

const (
	vulnUnknown vulnFindingType = iota
	vulnCalled
	vulnImported
	vulnRequired
)

// foundVuln returns the frame info describing discovered vulnerable symbol/package/module
// and how this vulnerability affects the analyzed package or module.
func foundVuln(finding *govulncheck.Finding) (*govulncheck.Frame, vulnFindingType) {
	// finding.Trace is sorted from the imported vulnerable symbol to
	// the entry point in the callstack.
	// If Function is set, then Package must be set. Module will always be set.
	// If Function is set it was found in the call graph, otherwise if Package is set
	// it was found in the import graph, otherwise it was found in the require graph.
	// See the documentation of govulncheck.Finding.
	if len(finding.Trace) == 0 { // this shouldn't happen, but just in case...
		return nil, vulnUnknown
	}
	vuln := finding.Trace[0]
	if vuln.Package == "" {
		return vuln, vulnRequired
	}
	if vuln.Function == "" {
		return vuln, vulnImported
	}
	return vuln, vulnCalled
}

func sortedKeys(m map[string]bool) []string {
	ret := make([]string, 0, len(m))
	for k := range m {
		ret = append(ret, k)
	}
	sort.Strings(ret)
	return ret
}

// suggestGovulncheckAction returns a code action that suggests either run govulncheck
// for more accurate investigation (if the present vulncheck diagnostics are based on
// analysis less accurate than govulncheck) or reset the existing govulncheck result
// (if the present vulncheck diagnostics are already based on govulncheck run).
func suggestGovulncheckAction(fromGovulncheck bool, uri protocol.DocumentURI) (cache.SuggestedFix, error) {
	if fromGovulncheck {
		resetVulncheck := command.NewResetGoModDiagnosticsCommand("Reset govulncheck result", command.ResetGoModDiagnosticsArgs{
			URIArg:           command.URIArg{URI: uri},
			DiagnosticSource: string(cache.Govulncheck),
		})
		return cache.SuggestedFixFromCommand(resetVulncheck, protocol.QuickFix), nil
	}
	vulncheck := command.NewRunGovulncheckCommand("Run govulncheck to verify", command.VulncheckArgs{
		URI:     uri,
		Pattern: "./...",
	})
	return cache.SuggestedFixFromCommand(vulncheck, protocol.QuickFix), nil
}

func getVulnMessage(mod string, vulns []string, used, fromGovulncheck bool) string {
	var b strings.Builder
	if used {
		switch len(vulns) {
		case 1:
			fmt.Fprintf(&b, "%v has a vulnerability used in the code: %v.", mod, vulns[0])
		default:
			fmt.Fprintf(&b, "%v has vulnerabilities used in the code: %v.", mod, strings.Join(vulns, ", "))
		}
	} else {
		if fromGovulncheck {
			switch len(vulns) {
			case 1:
				fmt.Fprintf(&b, "%v has a vulnerability %v that is not used in the code.", mod, vulns[0])
			default:
				fmt.Fprintf(&b, "%v has known vulnerabilities %v that are not used in the code.", mod, strings.Join(vulns, ", "))
			}
		} else {
			switch len(vulns) {
			case 1:
				fmt.Fprintf(&b, "%v has a vulnerability %v.", mod, vulns[0])
			default:
				fmt.Fprintf(&b, "%v has known vulnerabilities %v.", mod, strings.Join(vulns, ", "))
			}
		}
	}
	return b.String()
}

// href returns the url for the vulnerability information.
// Eventually we should retrieve the url embedded in the osv.Entry.
// While vuln.go.dev is under development, this always returns
// the page in pkg.go.dev.
func href(vulnID string) string {
	return fmt.Sprintf("https://pkg.go.dev/vuln/%s", vulnID)
}

func getUpgradeCodeAction(fh file.Handle, req *modfile.Require, version string) *protocol.Command {
	return command.NewUpgradeDependencyCommand(upgradeTitle(version), command.DependencyArgs{
		URI:        fh.URI(),
		AddRequire: false,
		GoCmdArgs:  []string{req.Mod.Path + "@" + version},
	})
}

func upgradeTitle(fixedVersion string) string {
	title := fmt.Sprintf("%s%v", upgradeCodeActionPrefix, fixedVersion)
	return title
}

// SelectUpgradeCodeActions takes a list of code actions for a required module
// and returns a more selective list of upgrade code actions,
// where the code actions have been deduped. Code actions unrelated to upgrade
// are deduplicated by the name.
func SelectUpgradeCodeActions(actions []protocol.CodeAction) []protocol.CodeAction {
	if len(actions) <= 1 {
		return actions // return early if no sorting necessary
	}
	var versionedUpgrade, latestUpgrade, resetAction protocol.CodeAction
	var chosenVersionedUpgrade string
	var selected []protocol.CodeAction

	seenTitles := make(map[string]bool)

	for _, action := range actions {
		if strings.HasPrefix(action.Title, upgradeCodeActionPrefix) {
			if v := getUpgradeVersion(action); v == "latest" && latestUpgrade.Title == "" {
				latestUpgrade = action
			} else if versionedUpgrade.Title == "" || semver.Compare(v, chosenVersionedUpgrade) > 0 {
				chosenVersionedUpgrade = v
				versionedUpgrade = action
			}
		} else if strings.HasPrefix(action.Title, "Reset govulncheck") {
			resetAction = action
		} else if !seenTitles[action.Command.Title] {
			seenTitles[action.Command.Title] = true
			selected = append(selected, action)
		}
	}
	if versionedUpgrade.Title != "" {
		selected = append(selected, versionedUpgrade)
	}
	if latestUpgrade.Title != "" {
		selected = append(selected, latestUpgrade)
	}
	if resetAction.Title != "" {
		selected = append(selected, resetAction)
	}
	return selected
}

func getUpgradeVersion(p protocol.CodeAction) string {
	return strings.TrimPrefix(p.Title, upgradeCodeActionPrefix)
}


================================================
FILE: gopls/internal/mod/format.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mod

import (
	"context"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
)

func Format(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.TextEdit, error) {
	ctx, done := event.Start(ctx, "mod.Format")
	defer done()

	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, err
	}
	formatted, err := pm.File.Format()
	if err != nil {
		return nil, err
	}
	// Calculate the edits to be made due to the change.
	diffs := diff.Bytes(pm.Mapper.Content, formatted)
	return protocol.EditsFromDiffEdits(pm.Mapper, diffs)
}


================================================
FILE: gopls/internal/mod/hover.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mod

import (
	"bytes"
	"context"
	"fmt"
	"slices"
	"sort"
	"strings"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
	"golang.org/x/mod/semver"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
	"golang.org/x/tools/internal/event"
)

func Hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) (*protocol.Hover, error) {
	// We only provide hover information for the view's go.mod files.
	if !slices.Contains(snapshot.View().ModFiles(), fh.URI()) {
		return nil, nil
	}

	ctx, done := event.Start(ctx, "mod.Hover")
	defer done()

	// Get the position of the cursor.
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, fmt.Errorf("getting modfile handle: %w", err)
	}
	startOffset, endOffset, err := pm.Mapper.RangeOffsets(rng)
	if err != nil {
		return nil, fmt.Errorf("computing cursor position: %w", err)
	}

	// If the cursor position is on a module statement
	if hover, ok := hoverOnModuleStatement(ctx, pm, startOffset, endOffset, snapshot, fh); ok {
		return hover, nil
	}
	return hoverOnRequireStatement(ctx, pm, startOffset, endOffset, snapshot, fh)
}

func hoverOnRequireStatement(ctx context.Context, pm *cache.ParsedModule, startOffset, endOffset int, snapshot *cache.Snapshot, fh file.Handle) (*protocol.Hover, error) {
	// Confirm that the cursor is at the position of a require statement.
	var req *modfile.Require
	var depStartOffset, depEndOffset int
	for _, r := range pm.File.Require {
		dep := []byte(r.Mod.Path)
		s, e := r.Syntax.Start.Byte, r.Syntax.End.Byte
		i := bytes.Index(pm.Mapper.Content[s:e], dep)
		if i == -1 {
			continue
		}
		// Shift the start position to the location of the
		// dependency within the require statement.
		depStartOffset, depEndOffset = s+i, e
		if depStartOffset <= startOffset && endOffset <= depEndOffset {
			req = r
			break
		}
	}
	// TODO(hyangah): find position for info about vulnerabilities in Go

	// The cursor position is not on a require statement.
	if req == nil {
		return nil, nil
	}

	// Get the vulnerability info.
	fromGovulncheck := true
	vs := snapshot.Vulnerabilities(fh.URI())[fh.URI()]
	if vs == nil && snapshot.Options().Vulncheck == settings.ModeVulncheckImports {
		var err error
		vs, err = snapshot.ModVuln(ctx, fh.URI())
		if err != nil {
			return nil, err
		}
		fromGovulncheck = false
	}
	affecting, nonaffecting, osvs := lookupVulns(vs, req.Mod.Path, req.Mod.Version)

	// Get the `go mod why` results for the given file.
	why, err := snapshot.ModWhy(ctx, fh)
	if err != nil {
		return nil, err
	}
	explanation, ok := why[req.Mod.Path]
	if !ok {
		return nil, nil
	}

	// Get the range to highlight for the hover.
	// TODO(hyangah): adjust the hover range to include the version number
	// to match the diagnostics' range.
	rng, err := pm.Mapper.OffsetRange(startOffset, endOffset)
	if err != nil {
		return nil, err
	}
	options := snapshot.Options()
	isPrivate := snapshot.IsGoPrivatePath(req.Mod.Path)
	header := formatHeader(req.Mod.Path, options)
	explanation = formatExplanation(explanation, pm.ReplaceMap, req, options, isPrivate)
	vulns := formatVulnerabilities(affecting, nonaffecting, osvs, options, fromGovulncheck)

	return &protocol.Hover{
		Contents: protocol.MarkupContent{
			Kind:  options.PreferredContentFormat,
			Value: header + vulns + explanation,
		},
		Range: rng,
	}, nil
}

func hoverOnModuleStatement(ctx context.Context, pm *cache.ParsedModule, startOffset, endOffset int, snapshot *cache.Snapshot, fh file.Handle) (*protocol.Hover, bool) {
	module := pm.File.Module
	if module == nil {
		return nil, false // no module stmt
	}
	if endOffset < module.Syntax.Start.Byte || startOffset > module.Syntax.End.Byte {
		return nil, false // cursor not in module stmt
	}

	rng, err := pm.Mapper.OffsetRange(module.Syntax.Start.Byte, module.Syntax.End.Byte)
	if err != nil {
		return nil, false
	}
	fromGovulncheck := true
	vs := snapshot.Vulnerabilities(fh.URI())[fh.URI()]

	if vs == nil && snapshot.Options().Vulncheck == settings.ModeVulncheckImports {
		vs, err = snapshot.ModVuln(ctx, fh.URI())
		if err != nil {
			return nil, false
		}
		fromGovulncheck = false
	}
	modpath := "stdlib"
	goVersion := snapshot.View().GoVersionString()
	affecting, nonaffecting, osvs := lookupVulns(vs, modpath, goVersion)
	options := snapshot.Options()
	vulns := formatVulnerabilities(affecting, nonaffecting, osvs, options, fromGovulncheck)

	return &protocol.Hover{
		Contents: protocol.MarkupContent{
			Kind:  options.PreferredContentFormat,
			Value: vulns,
		},
		Range: rng,
	}, true
}

func formatHeader(modpath string, options *settings.Options) string {
	var b strings.Builder
	// Write the heading as an H3.
	b.WriteString("#### " + modpath)
	if options.PreferredContentFormat == protocol.Markdown {
		b.WriteString("\n\n")
	} else {
		b.WriteRune('\n')
	}
	return b.String()
}

func lookupVulns(vulns *vulncheck.Result, modpath, version string) (affecting, nonaffecting []*govulncheck.Finding, osvs map[string]*osv.Entry) {
	if vulns == nil || len(vulns.Entries) == 0 {
		return nil, nil, nil
	}
	for _, finding := range vulns.Findings {
		vuln, typ := foundVuln(finding)
		if vuln.Module != modpath {
			continue
		}
		// It is possible that the source code was changed since the last
		// govulncheck run and information in the `vulns` info is stale.
		// For example, imagine that a user is in the middle of updating
		// problematic modules detected by the govulncheck run by applying
		// quick fixes. Stale diagnostics can be confusing and prevent the
		// user from quickly locating the next module to fix.
		// Ideally we should rerun the analysis with the updated module
		// dependencies or any other code changes, but we are not yet
		// in the position of automatically triggering the analysis
		// (govulncheck can take a while). We also don't know exactly what
		// part of source code was changed since `vulns` was computed.
		// As a heuristic, we assume that a user upgrades the affecting
		// module to the version with the fix or the latest one, and if the
		// version in the require statement is equal to or higher than the
		// fixed version, skip the vulnerability information in the hover.
		// Eventually, the user has to rerun govulncheck.
		if finding.FixedVersion != "" && semver.IsValid(version) && semver.Compare(finding.FixedVersion, version) <= 0 {
			continue
		}
		switch typ {
		case vulnCalled:
			affecting = append(affecting, finding)
		case vulnImported:
			nonaffecting = append(nonaffecting, finding)
		}
	}

	// Remove affecting elements from nonaffecting.
	// An OSV entry can appear in both lists if an OSV entry covers
	// multiple packages imported but not all vulnerable symbols are used.
	// The current wording of hover message doesn't clearly
	// present this case well IMO, so let's skip reporting nonaffecting.
	if len(affecting) > 0 && len(nonaffecting) > 0 {
		affectingSet := map[string]bool{}
		for _, f := range affecting {
			affectingSet[f.OSV] = true
		}
		n := 0
		for _, v := range nonaffecting {
			if !affectingSet[v.OSV] {
				nonaffecting[n] = v
				n++
			}
		}
		nonaffecting = nonaffecting[:n]
	}
	sort.Slice(nonaffecting, func(i, j int) bool { return nonaffecting[i].OSV < nonaffecting[j].OSV })
	sort.Slice(affecting, func(i, j int) bool { return affecting[i].OSV < affecting[j].OSV })
	return affecting, nonaffecting, vulns.Entries
}

func fixedVersion(fixed string) string {
	if fixed == "" {
		return "No fix is available."
	}
	return "Fixed in " + fixed + "."
}

func formatVulnerabilities(affecting, nonaffecting []*govulncheck.Finding, osvs map[string]*osv.Entry, options *settings.Options, fromGovulncheck bool) string {
	if len(osvs) == 0 || (len(affecting) == 0 && len(nonaffecting) == 0) {
		return ""
	}
	byOSV := func(findings []*govulncheck.Finding) map[string][]*govulncheck.Finding {
		m := make(map[string][]*govulncheck.Finding)
		for _, f := range findings {
			m[f.OSV] = append(m[f.OSV], f)
		}
		return m
	}
	affectingByOSV := byOSV(affecting)
	nonaffectingByOSV := byOSV(nonaffecting)

	// TODO(hyangah): can we use go templates to generate hover messages?
	// Then, we can use a different template for markdown case.
	useMarkdown := options.PreferredContentFormat == protocol.Markdown

	var b strings.Builder

	if len(affectingByOSV) > 0 {
		// TODO(hyangah): make the message more eyecatching (icon/codicon/color)
		if len(affectingByOSV) == 1 {
			fmt.Fprintf(&b, "\n**WARNING:** Found %d reachable vulnerability.\n", len(affectingByOSV))
		} else {
			fmt.Fprintf(&b, "\n**WARNING:** Found %d reachable vulnerabilities.\n", len(affectingByOSV))
		}
	}
	for id, findings := range affectingByOSV {
		fix := fixedVersion(findings[0].FixedVersion)
		pkgs := vulnerablePkgsInfo(findings, useMarkdown)
		osvEntry := osvs[id]

		if useMarkdown {
			fmt.Fprintf(&b, "- [**%v**](%v) %v%v\n%v\n", id, href(id), osvEntry.Summary, pkgs, fix)
		} else {
			fmt.Fprintf(&b, "  - [%v] %v (%v) %v%v\n", id, osvEntry.Summary, href(id), pkgs, fix)
		}
	}
	if len(nonaffecting) > 0 {
		if fromGovulncheck {
			fmt.Fprintf(&b, "\n**Note:** The project imports packages with known vulnerabilities, but does not call the vulnerable code.\n")
		} else {
			fmt.Fprintf(&b, "\n**Note:** The project imports packages with known vulnerabilities. Use `govulncheck` to check if the project uses vulnerable symbols.\n")
		}
	}
	for k, findings := range nonaffectingByOSV {
		fix := fixedVersion(findings[0].FixedVersion)
		pkgs := vulnerablePkgsInfo(findings, useMarkdown)
		osvEntry := osvs[k]

		if useMarkdown {
			fmt.Fprintf(&b, "- [%v](%v) %v%v\n%v\n", k, href(k), osvEntry.Summary, pkgs, fix)
		} else {
			fmt.Fprintf(&b, "  - [%v] %v (%v) %v\n%v\n", k, osvEntry.Summary, href(k), pkgs, fix)
		}
	}
	b.WriteString("\n")
	return b.String()
}

func vulnerablePkgsInfo(findings []*govulncheck.Finding, useMarkdown bool) string {
	var b strings.Builder
	seen := map[string]bool{}
	for _, f := range findings {
		p := f.Trace[0].Package
		if !seen[p] {
			seen[p] = true
			if useMarkdown {
				b.WriteString("\n  * `")
			} else {
				b.WriteString("\n    ")
			}
			b.WriteString(p)
			if useMarkdown {
				b.WriteString("`")
			}
		}
	}
	return b.String()
}

func formatExplanation(text string, replaceMap map[module.Version]module.Version, req *modfile.Require, options *settings.Options, isPrivate bool) string {
	text = strings.TrimSuffix(text, "\n")
	splt := strings.Split(text, "\n")
	length := len(splt)

	var b strings.Builder

	// If the explanation is 2 lines, then it is of the form:
	// # golang.org/x/text/encoding
	// (main module does not need package golang.org/x/text/encoding)
	if length == 2 {
		b.WriteString(splt[1])
		return b.String()
	}

	imp := splt[length-1] // import path
	reference := imp
	// See golang/go#36998: don't link to modules matching GOPRIVATE.
	if !isPrivate && options.PreferredContentFormat == protocol.Markdown {
		target := imp
		if strings.ToLower(options.LinkTarget) == "pkg.go.dev" {
			mod := req.Mod
			// respect the replacement when constructing a module link.
			if m, ok := replaceMap[req.Mod]; ok {
				// Have: 'replace A v1.2.3 => A vx.x.x' or 'replace A v1.2.3 => B vx.x.x'.
				mod = m
			} else if m, ok := replaceMap[module.Version{Path: req.Mod.Path}]; ok &&
				!modfile.IsDirectoryPath(m.Path) { // exclude local replacement.
				// Have: 'replace A => A vx.x.x' or 'replace A => B vx.x.x'.
				mod = m
			}
			target = strings.Replace(target, req.Mod.Path, mod.String(), 1)
		}
		reference = fmt.Sprintf("[%s](%s)", imp, cache.BuildLink(options.LinkTarget, target, ""))
	}
	b.WriteString("This module is necessary because " + reference + " is imported in")

	// If the explanation is 3 lines, then it is of the form:
	// # golang.org/x/tools
	// modtest
	// golang.org/x/tools/go/packages
	if length == 3 {
		msg := fmt.Sprintf(" `%s`.", splt[1])
		b.WriteString(msg)
		return b.String()
	}

	// If the explanation is more than 3 lines, then it is of the form:
	// # golang.org/x/text/language
	// rsc.io/quote
	// rsc.io/sampler
	// golang.org/x/text/language
	b.WriteString(":\n```text")
	var dash strings.Builder
	for _, imp := range splt[1 : length-1] {
		dash.WriteString("-")
		b.WriteString("\n" + dash.String() + " " + imp)
	}
	b.WriteString("\n```")
	return b.String()
}


================================================
FILE: gopls/internal/mod/inlay_hint.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package mod

import (
	"context"
	"fmt"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

func InlayHint(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, _ protocol.Range) ([]protocol.InlayHint, error) {
	// Inlay hints are enabled if the client supports them.
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, err
	}

	// Compare the version of the module used in the snapshot's
	// metadata (i.e. the solution to the MVS constraints computed
	// by go list) with the version requested by the module, in
	// both cases, taking replaces into account. Produce an
	// InlayHint when the version of the module is not the one
	// used.

	replaces := make(map[string]*modfile.Replace)
	for _, x := range pm.File.Replace {
		replaces[x.Old.Path] = x
	}

	requires := make(map[string]*modfile.Require)
	for _, x := range pm.File.Require {
		requires[x.Mod.Path] = x
	}

	am, err := snapshot.AllMetadata(ctx)
	if err != nil {
		return nil, err
	}

	var ans []protocol.InlayHint
	seen := make(map[string]bool)
	for _, meta := range am {
		if meta.Module == nil || seen[meta.Module.Path] {
			continue
		}
		seen[meta.Module.Path] = true
		metaVersion := meta.Module.Version
		if meta.Module.Replace != nil {
			metaVersion = meta.Module.Replace.Version
		}
		// These versions can be blank, as in gopls/go.mod's local replace
		if oldrepl, ok := replaces[meta.Module.Path]; ok && oldrepl.New.Version != metaVersion {
			ih := genHint(oldrepl.Syntax, oldrepl.New.Version, metaVersion, pm.Mapper)
			if ih != nil {
				ans = append(ans, *ih)
			}
		} else if oldreq, ok := requires[meta.Module.Path]; ok && oldreq.Mod.Version != metaVersion {
			// maybe it was replaced:
			if _, ok := replaces[meta.Module.Path]; ok {
				continue
			}
			ih := genHint(oldreq.Syntax, oldreq.Mod.Version, metaVersion, pm.Mapper)
			if ih != nil {
				ans = append(ans, *ih)
			}
		}
	}
	return ans, nil
}

func genHint(mline *modfile.Line, oldVersion, newVersion string, m *protocol.Mapper) *protocol.InlayHint {
	x := mline.End.Byte // the parser has removed trailing whitespace and comments (see modfile_test.go)
	x -= len(mline.Token[len(mline.Token)-1])
	line, err := m.OffsetPosition(x)
	if err != nil {
		return nil
	}
	part := protocol.InlayHintLabelPart{
		Value: newVersion,
		Tooltip: &protocol.OrPTooltipPLabel{
			Value: fmt.Sprintf("The build selects version %s rather than go.mod's version %s.", newVersion, oldVersion),
		},
	}
	rng, err := m.OffsetRange(x, mline.End.Byte)
	if err != nil {
		return nil
	}
	te := protocol.TextEdit{
		Range:   rng,
		NewText: newVersion,
	}
	return &protocol.InlayHint{
		Position:     line,
		Label:        []protocol.InlayHintLabelPart{part},
		Kind:         protocol.Parameter,
		PaddingRight: true,
		TextEdits:    []protocol.TextEdit{te},
	}
}


================================================
FILE: gopls/internal/mod/references.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mod

import (
	"context"
	"fmt"
	"maps"
	"slices"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

// References returns the locations of imports referenced by a required module
func References(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, params *protocol.ReferenceParams) ([]protocol.Location, error) {
	// Th go.mod file will contain a module name (e.g., golang.org/x/tools)
	// but the import statements contain package names
	// (e.g., golang.org/x/tools/internal/astutil).
	// The code has to avoid imports from submodules, like golang.org/x/tools/gopls/internal/file
	// so simple string matching would not work.

	// find modpath, the module path the user wants the references for
	gomod, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, err
	}
	if gomod.File == nil {
		return nil, fmt.Errorf("mysterious parse failure %s", fh.URI().Path())
	}
	// protocol.ReferenceParams contains both a Position and a Range.
	// The Range would contain the Position, so use Position.
	offset, err := gomod.Mapper.PositionOffset(params.Position)
	if err != nil {
		return nil, err
	}
	var modpath string
	for _, req := range gomod.File.Require {
		if req.Syntax.Start.Byte <= offset && offset <= req.Syntax.End.Byte {
			modpath = req.Mod.Path
			break
		}
	}
	if modpath == "" {
		// nothing to report
		return nil, nil
	}

	locs := make(map[protocol.Location]bool)

	includeDecl := params.Context.IncludeDeclaration
	// A. find the IDs of all packages in the module that was required
	ids := make(map[metadata.PackageID]bool)
	g := snapshot.MetadataGraph()
	for _, pkg := range g.Packages {
		if pkg.Module != nil && pkg.Module.Path == modpath {
			ids[pkg.ID] = true
			// once, if the definition is needed
			if includeDecl {
				fh, err := snapshot.ReadFile(ctx, protocol.URIFromPath(pkg.Module.GoMod))
				if err != nil {
					return nil, err
				}
				parsed, err := snapshot.ParseMod(ctx, fh)
				if err != nil {
					return nil, err
				}
				if parsed.File != nil && parsed.File.Module != nil {
					start, end := parsed.File.Module.Syntax.Span()
					loc, err := parsed.Mapper.OffsetLocation(start.Byte, end.Byte)
					if err != nil {
						return nil, err
					}
					locs[loc] = true
					includeDecl = false // no need to do this again
				}
			}
		}
	}
	// B. find all the importers of these packages that are in the go.mod's module
	uris := make(map[protocol.DocumentURI]*metadata.Package)
	for id := range ids {
		for _, importer := range g.ImportedBy[id] {
			if importer.Module.GoMod != gomod.URI.Path() {
				continue
			}
			// files to be read.
			// at least one of them has an import to be reported.
			for _, uri := range importer.CompiledGoFiles {
				upkgs := g.ForFile[uri]
				for _, upkg := range upkgs {
					if upkg.ID == importer.ID {
						uris[uri] = importer // may overwrite, but it doesn't matter
						break
					}
				}
			}
		}
	}
	// C. for each of the uris, pick out the locs of imports from the requested module
	for uri := range uris {
		fh, err := snapshot.ReadFile(ctx, uri)
		if err != nil {
			return nil, err
		}
		pgf, err := snapshot.ParseGo(ctx, fh, parsego.Header) // Header promotes cache hits
		if err != nil {
			return nil, err
		}
		xpkg := uris[uri]
		for _, spec := range pgf.File.Imports {
			importPath := metadata.UnquoteImportPath(spec)
			if ids[xpkg.DepsByImpPath[importPath]] {
				loc, err := pgf.NodeLocation(spec.Path)
				if err != nil {
					return nil, err
				}
				locs[loc] = true
				continue
			}
		}
	}

	ans := slices.SortedFunc(maps.Keys(locs), protocol.CompareLocation)
	return ans, nil
}


================================================
FILE: gopls/internal/progress/progress.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The progress package defines utilities for reporting the progress
// of long-running operations using features of the LSP client
// interface such as Progress and ShowMessage.
package progress

import (
	"context"
	"fmt"
	"io"
	"math/rand"
	"strconv"
	"strings"
	"sync"

	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/xcontext"
)

// NewTracker returns a new Tracker that reports progress to the
// specified client.
func NewTracker(client protocol.Client) *Tracker {
	return &Tracker{
		client:     client,
		inProgress: make(map[protocol.ProgressToken]*WorkDone),
	}
}

// A Tracker reports the progress of a long-running operation to an LSP client.
type Tracker struct {
	client                   protocol.Client
	supportsWorkDoneProgress bool

	mu         sync.Mutex
	inProgress map[protocol.ProgressToken]*WorkDone
}

// SetSupportsWorkDoneProgress sets whether the client supports "work done"
// progress reporting. It must be set before using the tracker.
//
// TODO(rfindley): fix this broken initialization pattern.
// Also: do we actually need the fall-back progress behavior using ShowMessage?
// Surely ShowMessage notifications are too noisy to be worthwhile.
func (t *Tracker) SetSupportsWorkDoneProgress(b bool) {
	t.supportsWorkDoneProgress = b
}

// SupportsWorkDoneProgress reports whether the tracker supports work done
// progress reporting.
func (t *Tracker) SupportsWorkDoneProgress() bool {
	return t.supportsWorkDoneProgress
}

// Start notifies the client of work being done on the server. It uses either
// ShowMessage RPCs or $/progress messages, depending on the capabilities of
// the client.  The returned WorkDone handle may be used to report incremental
// progress, and to report work completion. In particular, it is an error to
// call start and not call end(...) on the returned WorkDone handle.
//
// If token is empty, a token will be randomly generated.
//
// The progress item is considered cancellable if the given cancel func is
// non-nil. In this case, cancel is called when the work done
//
// Example:
//
//	func Generate(ctx) (err error) {
//	  ctx, cancel := context.WithCancel(ctx)
//	  defer cancel()
//	  work := s.progress.start(ctx, "generate", "running go generate", cancel)
//	  defer func() {
//	    if err != nil {
//	      work.end(ctx, fmt.Sprintf("generate failed: %v", err))
//	    } else {
//	      work.end(ctx, "done")
//	    }
//	  }()
//	  // Do the work...
//	}
func (t *Tracker) Start(ctx context.Context, title, message string, token protocol.ProgressToken, cancel func()) *WorkDone {
	ctx = xcontext.Detach(ctx) // progress messages should not be cancelled
	wd := &WorkDone{
		client: t.client,
		token:  token,
		cancel: cancel,
	}
	if !t.supportsWorkDoneProgress {
		// Previous iterations of this fallback attempted to retain cancellation
		// support by using ShowMessageCommand with a 'Cancel' button, but this is
		// not ideal as the 'Cancel' dialog stays open even after the command
		// completes.
		//
		// Just show a simple message. Clients can implement workDone progress
		// reporting to get cancellation support.
		if err := wd.client.ShowMessage(ctx, &protocol.ShowMessageParams{
			Type:    protocol.Log,
			Message: message,
		}); err != nil {
			event.Error(ctx, "showing start message for "+title, err)
		}
		return wd
	}
	if wd.token == nil {
		token = strconv.FormatInt(rand.Int63(), 10)
		err := wd.client.WorkDoneProgressCreate(ctx, &protocol.WorkDoneProgressCreateParams{
			Token: token,
		})
		if err != nil {
			wd.err = err
			event.Error(ctx, "starting work for "+title, err)
			return wd
		}
		wd.token = token
	}
	// At this point we have a token that the client knows about. Store the token
	// before starting work.
	t.mu.Lock()
	t.inProgress[wd.token] = wd
	t.mu.Unlock()
	wd.cleanup = func() {
		t.mu.Lock()
		delete(t.inProgress, token)
		t.mu.Unlock()
	}
	err := wd.client.Progress(ctx, &protocol.ProgressParams{
		Token: wd.token,
		Value: &protocol.WorkDoneProgressBegin{
			Kind:        "begin",
			Cancellable: wd.cancel != nil,
			Message:     message,
			Title:       title,
		},
	})
	if err != nil {
		event.Error(ctx, "progress begin", err)
	}
	return wd
}

func (t *Tracker) Cancel(token protocol.ProgressToken) error {
	t.mu.Lock()
	defer t.mu.Unlock()
	wd, ok := t.inProgress[token]
	if !ok {
		return fmt.Errorf("token %q not found in progress", token)
	}
	if wd.cancel == nil {
		return fmt.Errorf("work %q is not cancellable", token)
	}
	wd.doCancel()
	return nil
}

// WorkDone represents a unit of work that is reported to the client via the
// progress API.
type WorkDone struct {
	client protocol.Client
	// If token is nil, this workDone object uses the ShowMessage API, rather
	// than $/progress.
	token protocol.ProgressToken
	// err is set if progress reporting is broken for some reason (for example,
	// if there was an initial error creating a token).
	err error

	cancelMu  sync.Mutex
	cancelled bool
	cancel    func()

	cleanup func()
}

func (wd *WorkDone) Token() protocol.ProgressToken {
	return wd.token
}

func (wd *WorkDone) doCancel() {
	wd.cancelMu.Lock()
	defer wd.cancelMu.Unlock()
	if !wd.cancelled {
		wd.cancel()
	}
}

// Report reports an update on WorkDone report back to the client.
func (wd *WorkDone) Report(ctx context.Context, message string, fraction float64) {
	ctx = xcontext.Detach(ctx) // progress messages should not be cancelled
	if wd == nil {
		return
	}
	wd.cancelMu.Lock()
	cancelled := wd.cancelled
	wd.cancelMu.Unlock()
	if cancelled {
		return
	}
	if wd.err != nil || wd.token == nil {
		// Not using the workDone API, so we do nothing. It would be far too spammy
		// to send incremental messages.
		return
	}
	message = strings.TrimSuffix(message, "\n")
	percentage := uint32(100 * fraction)
	err := wd.client.Progress(ctx, &protocol.ProgressParams{
		Token: wd.token,
		Value: &protocol.WorkDoneProgressReport{
			Kind: "report",
			// Note that in the LSP spec, the value of Cancellable may be changed to
			// control whether the cancel button in the UI is enabled. Since we don't
			// yet use this feature, the value is kept constant here.
			Cancellable: wd.cancel != nil,
			Message:     message,
			Percentage:  &percentage,
		},
	})
	if err != nil {
		event.Error(ctx, "reporting progress", err)
	}
}

// End reports a workdone completion back to the client.
func (wd *WorkDone) End(ctx context.Context, message string) {
	ctx = xcontext.Detach(ctx) // progress messages should not be cancelled
	if wd == nil {
		return
	}
	var err error
	switch {
	case wd.err != nil:
		// There is a prior error.
	case wd.token == nil:
		// We're falling back to message-based reporting.
		err = wd.client.ShowMessage(ctx, &protocol.ShowMessageParams{
			Type:    protocol.Info,
			Message: message,
		})
	default:
		err = wd.client.Progress(ctx, &protocol.ProgressParams{
			Token: wd.token,
			Value: &protocol.WorkDoneProgressEnd{
				Kind:    "end",
				Message: message,
			},
		})
	}
	if err != nil {
		event.Error(ctx, "ending work", err)
	}
	if wd.cleanup != nil {
		wd.cleanup()
	}
}

// NewEventWriter returns an [io.Writer] that calls the context's
// event printer for each data payload, wrapping it with the
// operation=generate tag to distinguish its logs from others.
func NewEventWriter(ctx context.Context, operation string) io.Writer {
	return &eventWriter{ctx: ctx, operation: operation}
}

type eventWriter struct {
	ctx       context.Context
	operation string
}

func (ew *eventWriter) Write(p []byte) (n int, err error) {
	event.Log(ew.ctx, string(p), label.Operation.Of(ew.operation))
	return len(p), nil
}

// NewWorkDoneWriter wraps a WorkDone handle to provide a Writer interface,
// so that workDone reporting can more easily be hooked into commands.
func NewWorkDoneWriter(ctx context.Context, wd *WorkDone) io.Writer {
	return &workDoneWriter{ctx: ctx, wd: wd}
}

// workDoneWriter wraps a workDone handle to provide a Writer interface,
// so that workDone reporting can more easily be hooked into commands.
type workDoneWriter struct {
	// In order to implement the io.Writer interface, we must close over ctx.
	ctx context.Context
	wd  *WorkDone
}

func (wdw *workDoneWriter) Write(p []byte) (n int, err error) {
	wdw.wd.Report(wdw.ctx, string(p), 0)
	// Don't fail just because of a failure to report progress.
	return len(p), nil
}


================================================
FILE: gopls/internal/progress/progress_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package progress

import (
	"context"
	"fmt"
	"sync"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

type fakeClient struct {
	protocol.Client

	token protocol.ProgressToken

	mu                                        sync.Mutex
	created, begun, reported, messages, ended int
}

func (c *fakeClient) checkToken(token protocol.ProgressToken) {
	if token == nil {
		panic("nil token in progress message")
	}
	if c.token != nil && c.token != token {
		panic(fmt.Errorf("invalid token in progress message: got %v, want %v", token, c.token))
	}
}

func (c *fakeClient) WorkDoneProgressCreate(ctx context.Context, params *protocol.WorkDoneProgressCreateParams) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.checkToken(params.Token)
	c.created++
	return nil
}

func (c *fakeClient) Progress(ctx context.Context, params *protocol.ProgressParams) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.checkToken(params.Token)
	switch params.Value.(type) {
	case *protocol.WorkDoneProgressBegin:
		c.begun++
	case *protocol.WorkDoneProgressReport:
		c.reported++
	case *protocol.WorkDoneProgressEnd:
		c.ended++
	default:
		panic(fmt.Errorf("unknown progress value %T", params.Value))
	}
	return nil
}

func (c *fakeClient) ShowMessage(context.Context, *protocol.ShowMessageParams) error {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.messages++
	return nil
}

func setup() (*Tracker, *fakeClient) {
	c := &fakeClient{}
	tracker := NewTracker(c)
	tracker.SetSupportsWorkDoneProgress(true)
	return tracker, c
}

func TestProgressTracker_Reporting(t *testing.T) {
	for _, test := range []struct {
		name                                            string
		supported                                       bool
		token                                           protocol.ProgressToken
		wantReported, wantCreated, wantBegun, wantEnded int
		wantMessages                                    int
	}{
		{
			name:         "unsupported",
			wantMessages: 2,
		},
		{
			name:         "random token",
			supported:    true,
			wantCreated:  1,
			wantBegun:    1,
			wantReported: 1,
			wantEnded:    1,
		},
		{
			name:         "string token",
			supported:    true,
			token:        "token",
			wantBegun:    1,
			wantReported: 1,
			wantEnded:    1,
		},
		{
			name:         "numeric token",
			supported:    true,
			token:        1,
			wantReported: 1,
			wantBegun:    1,
			wantEnded:    1,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			tracker, client := setup()
			ctx := t.Context()
			tracker.supportsWorkDoneProgress = test.supported
			work := tracker.Start(ctx, "work", "message", test.token, nil)
			client.mu.Lock()
			gotCreated, gotBegun := client.created, client.begun
			client.mu.Unlock()
			if gotCreated != test.wantCreated {
				t.Errorf("got %d created tokens, want %d", gotCreated, test.wantCreated)
			}
			if gotBegun != test.wantBegun {
				t.Errorf("got %d work begun, want %d", gotBegun, test.wantBegun)
			}
			// Ignore errors: this is just testing the reporting behavior.
			work.Report(ctx, "report", 0.5)
			client.mu.Lock()
			gotReported := client.reported
			client.mu.Unlock()
			if gotReported != test.wantReported {
				t.Errorf("got %d progress reports, want %d", gotReported, test.wantCreated)
			}
			work.End(ctx, "done")
			client.mu.Lock()
			gotEnded, gotMessages := client.ended, client.messages
			client.mu.Unlock()
			if gotEnded != test.wantEnded {
				t.Errorf("got %d ended reports, want %d", gotEnded, test.wantEnded)
			}
			if gotMessages != test.wantMessages {
				t.Errorf("got %d messages, want %d", gotMessages, test.wantMessages)
			}
		})
	}
}

func TestProgressTracker_Cancellation(t *testing.T) {
	for _, token := range []protocol.ProgressToken{nil, 1, "a"} {
		tracker, _ := setup()
		var canceled bool
		cancel := func() { canceled = true }
		work := tracker.Start(t.Context(), "work", "message", token, cancel)
		if err := tracker.Cancel(work.Token()); err != nil {
			t.Fatal(err)
		}
		if !canceled {
			t.Errorf("tracker.cancel(...): cancel not called")
		}
	}
}


================================================
FILE: gopls/internal/protocol/command/command_gen.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Don't include this file during code generation, or it will break the build
// if existing interface methods have been modified.
//go:build !generate
// +build !generate

// Code generated by gen.go from gopls/internal/protocol/command. DO NOT EDIT.

package command

import (
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
)

// Symbolic names for gopls commands, corresponding to methods of [Interface].
//
// The string value is used in the Command field of protocol.Command.
// These commands may be obtained from a CodeLens or CodeAction request
// and executed by an ExecuteCommand request.
const (
	AddDependency           Command = "gopls.add_dependency"
	AddImport               Command = "gopls.add_import"
	AddTelemetryCounters    Command = "gopls.add_telemetry_counters"
	AddTest                 Command = "gopls.add_test"
	ApplyFix                Command = "gopls.apply_fix"
	Assembly                Command = "gopls.assembly"
	ChangeSignature         Command = "gopls.change_signature"
	CheckUpgrades           Command = "gopls.check_upgrades"
	ClientOpenURL           Command = "gopls.client_open_url"
	DiagnoseFiles           Command = "gopls.diagnose_files"
	Doc                     Command = "gopls.doc"
	EditGoDirective         Command = "gopls.edit_go_directive"
	ExtractToNewFile        Command = "gopls.extract_to_new_file"
	FetchVulncheckResult    Command = "gopls.fetch_vulncheck_result"
	FreeSymbols             Command = "gopls.free_symbols"
	GCDetails               Command = "gopls.gc_details"
	Generate                Command = "gopls.generate"
	GoGetPackage            Command = "gopls.go_get_package"
	ListImports             Command = "gopls.list_imports"
	ListKnownPackages       Command = "gopls.list_known_packages"
	LSP                     Command = "gopls.lsp"
	MaybePromptForTelemetry Command = "gopls.maybe_prompt_for_telemetry"
	MemStats                Command = "gopls.mem_stats"
	ModifyTags              Command = "gopls.modify_tags"
	Modules                 Command = "gopls.modules"
	MoveType                Command = "gopls.move_type"
	PackageSymbols          Command = "gopls.package_symbols"
	Packages                Command = "gopls.packages"
	RegenerateCgo           Command = "gopls.regenerate_cgo"
	RemoveDependency        Command = "gopls.remove_dependency"
	ResetGoModDiagnostics   Command = "gopls.reset_go_mod_diagnostics"
	RunGoWorkCommand        Command = "gopls.run_go_work_command"
	RunGovulncheck          Command = "gopls.run_govulncheck"
	RunTests                Command = "gopls.run_tests"
	ScanImports             Command = "gopls.scan_imports"
	SplitPackage            Command = "gopls.split_package"
	StartDebugging          Command = "gopls.start_debugging"
	StartProfile            Command = "gopls.start_profile"
	StopProfile             Command = "gopls.stop_profile"
	Tidy                    Command = "gopls.tidy"
	UpdateGoSum             Command = "gopls.update_go_sum"
	UpgradeDependency       Command = "gopls.upgrade_dependency"
	Vendor                  Command = "gopls.vendor"
	Views                   Command = "gopls.views"
	Vulncheck               Command = "gopls.vulncheck"
	WorkspaceStats          Command = "gopls.workspace_stats"
)

var Commands = []Command{
	AddDependency,
	AddImport,
	AddTelemetryCounters,
	AddTest,
	ApplyFix,
	Assembly,
	ChangeSignature,
	CheckUpgrades,
	ClientOpenURL,
	DiagnoseFiles,
	Doc,
	EditGoDirective,
	ExtractToNewFile,
	FetchVulncheckResult,
	FreeSymbols,
	GCDetails,
	Generate,
	GoGetPackage,
	ListImports,
	ListKnownPackages,
	LSP,
	MaybePromptForTelemetry,
	MemStats,
	ModifyTags,
	Modules,
	MoveType,
	PackageSymbols,
	Packages,
	RegenerateCgo,
	RemoveDependency,
	ResetGoModDiagnostics,
	RunGoWorkCommand,
	RunGovulncheck,
	RunTests,
	ScanImports,
	SplitPackage,
	StartDebugging,
	StartProfile,
	StopProfile,
	Tidy,
	UpdateGoSum,
	UpgradeDependency,
	Vendor,
	Views,
	Vulncheck,
	WorkspaceStats,
}

func Dispatch(ctx context.Context, params *protocol.ExecuteCommandParams, s Interface) (any, error) {
	switch Command(params.Command) {
	case AddDependency:
		var a0 DependencyArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.AddDependency(ctx, a0)
	case AddImport:
		var a0 AddImportArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.AddImport(ctx, a0)
	case AddTelemetryCounters:
		var a0 AddTelemetryCountersArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.AddTelemetryCounters(ctx, a0)
	case AddTest:
		var a0 protocol.Location
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.AddTest(ctx, a0)
	case ApplyFix:
		var a0 ApplyFixArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.ApplyFix(ctx, a0)
	case Assembly:
		var a0 string
		var a1 string
		var a2 string
		if err := UnmarshalArgs(params.Arguments, &a0, &a1, &a2); err != nil {
			return nil, err
		}
		return nil, s.Assembly(ctx, a0, a1, a2)
	case ChangeSignature:
		var a0 ChangeSignatureArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.ChangeSignature(ctx, a0)
	case CheckUpgrades:
		var a0 CheckUpgradesArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.CheckUpgrades(ctx, a0)
	case ClientOpenURL:
		var a0 string
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.ClientOpenURL(ctx, a0)
	case DiagnoseFiles:
		var a0 DiagnoseFilesArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.DiagnoseFiles(ctx, a0)
	case Doc:
		var a0 DocArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.Doc(ctx, a0)
	case EditGoDirective:
		var a0 EditGoDirectiveArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.EditGoDirective(ctx, a0)
	case ExtractToNewFile:
		var a0 protocol.Location
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.ExtractToNewFile(ctx, a0)
	case FetchVulncheckResult:
		var a0 URIArg
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.FetchVulncheckResult(ctx, a0)
	case FreeSymbols:
		var a0 string
		var a1 protocol.Location
		if err := UnmarshalArgs(params.Arguments, &a0, &a1); err != nil {
			return nil, err
		}
		return nil, s.FreeSymbols(ctx, a0, a1)
	case GCDetails:
		var a0 protocol.DocumentURI
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.GCDetails(ctx, a0)
	case Generate:
		var a0 GenerateArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.Generate(ctx, a0)
	case GoGetPackage:
		var a0 GoGetPackageArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.GoGetPackage(ctx, a0)
	case ListImports:
		var a0 URIArg
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.ListImports(ctx, a0)
	case ListKnownPackages:
		var a0 URIArg
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.ListKnownPackages(ctx, a0)
	case LSP:
		var a0 LSPArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.LSP(ctx, a0)
	case MaybePromptForTelemetry:
		return nil, s.MaybePromptForTelemetry(ctx)
	case MemStats:
		return s.MemStats(ctx)
	case ModifyTags:
		var a0 ModifyTagsArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.ModifyTags(ctx, a0)
	case Modules:
		var a0 ModulesArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.Modules(ctx, a0)
	case MoveType:
		var a0 MoveTypeArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.MoveType(ctx, a0)
	case PackageSymbols:
		var a0 PackageSymbolsArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.PackageSymbols(ctx, a0)
	case Packages:
		var a0 PackagesArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.Packages(ctx, a0)
	case RegenerateCgo:
		var a0 URIArg
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.RegenerateCgo(ctx, a0)
	case RemoveDependency:
		var a0 RemoveDependencyArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.RemoveDependency(ctx, a0)
	case ResetGoModDiagnostics:
		var a0 ResetGoModDiagnosticsArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.ResetGoModDiagnostics(ctx, a0)
	case RunGoWorkCommand:
		var a0 RunGoWorkArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.RunGoWorkCommand(ctx, a0)
	case RunGovulncheck:
		var a0 VulncheckArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.RunGovulncheck(ctx, a0)
	case RunTests:
		var a0 RunTestsArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.RunTests(ctx, a0)
	case ScanImports:
		return nil, s.ScanImports(ctx)
	case SplitPackage:
		var a0 string
		var a1 string
		if err := UnmarshalArgs(params.Arguments, &a0, &a1); err != nil {
			return nil, err
		}
		return nil, s.SplitPackage(ctx, a0, a1)
	case StartDebugging:
		var a0 DebuggingArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.StartDebugging(ctx, a0)
	case StartProfile:
		var a0 StartProfileArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.StartProfile(ctx, a0)
	case StopProfile:
		var a0 StopProfileArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.StopProfile(ctx, a0)
	case Tidy:
		var a0 URIArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.Tidy(ctx, a0)
	case UpdateGoSum:
		var a0 URIArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.UpdateGoSum(ctx, a0)
	case UpgradeDependency:
		var a0 DependencyArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.UpgradeDependency(ctx, a0)
	case Vendor:
		var a0 URIArg
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return nil, s.Vendor(ctx, a0)
	case Views:
		return s.Views(ctx)
	case Vulncheck:
		var a0 VulncheckArgs
		if err := UnmarshalArgs(params.Arguments, &a0); err != nil {
			return nil, err
		}
		return s.Vulncheck(ctx, a0)
	case WorkspaceStats:
		return s.WorkspaceStats(ctx)
	}
	return nil, fmt.Errorf("unsupported command %q", params.Command)
}

func NewAddDependencyCommand(title string, a0 DependencyArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   AddDependency.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewAddImportCommand(title string, a0 AddImportArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   AddImport.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewAddTelemetryCountersCommand(title string, a0 AddTelemetryCountersArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   AddTelemetryCounters.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewAddTestCommand(title string, a0 protocol.Location) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   AddTest.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewApplyFixCommand(title string, a0 ApplyFixArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ApplyFix.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewAssemblyCommand(title string, a0 string, a1 string, a2 string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Assembly.String(),
		Arguments: MustMarshalArgs(a0, a1, a2),
	}
}

func NewChangeSignatureCommand(title string, a0 ChangeSignatureArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ChangeSignature.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewCheckUpgradesCommand(title string, a0 CheckUpgradesArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   CheckUpgrades.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewClientOpenURLCommand(title string, a0 string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ClientOpenURL.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewDiagnoseFilesCommand(title string, a0 DiagnoseFilesArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   DiagnoseFiles.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewDocCommand(title string, a0 DocArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Doc.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewEditGoDirectiveCommand(title string, a0 EditGoDirectiveArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   EditGoDirective.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewExtractToNewFileCommand(title string, a0 protocol.Location) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ExtractToNewFile.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewFetchVulncheckResultCommand(title string, a0 URIArg) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   FetchVulncheckResult.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewFreeSymbolsCommand(title string, a0 string, a1 protocol.Location) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   FreeSymbols.String(),
		Arguments: MustMarshalArgs(a0, a1),
	}
}

func NewGCDetailsCommand(title string, a0 protocol.DocumentURI) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   GCDetails.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewGenerateCommand(title string, a0 GenerateArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Generate.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewGoGetPackageCommand(title string, a0 GoGetPackageArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   GoGetPackage.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewListImportsCommand(title string, a0 URIArg) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ListImports.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewListKnownPackagesCommand(title string, a0 URIArg) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ListKnownPackages.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewLSPCommand(title string, a0 LSPArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   LSP.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewMaybePromptForTelemetryCommand(title string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   MaybePromptForTelemetry.String(),
		Arguments: MustMarshalArgs(),
	}
}

func NewMemStatsCommand(title string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   MemStats.String(),
		Arguments: MustMarshalArgs(),
	}
}

func NewModifyTagsCommand(title string, a0 ModifyTagsArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ModifyTags.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewModulesCommand(title string, a0 ModulesArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Modules.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewMoveTypeCommand(title string, a0 MoveTypeArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   MoveType.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewPackageSymbolsCommand(title string, a0 PackageSymbolsArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   PackageSymbols.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewPackagesCommand(title string, a0 PackagesArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Packages.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewRegenerateCgoCommand(title string, a0 URIArg) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   RegenerateCgo.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewRemoveDependencyCommand(title string, a0 RemoveDependencyArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   RemoveDependency.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewResetGoModDiagnosticsCommand(title string, a0 ResetGoModDiagnosticsArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ResetGoModDiagnostics.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewRunGoWorkCommandCommand(title string, a0 RunGoWorkArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   RunGoWorkCommand.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewRunGovulncheckCommand(title string, a0 VulncheckArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   RunGovulncheck.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewRunTestsCommand(title string, a0 RunTestsArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   RunTests.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewScanImportsCommand(title string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   ScanImports.String(),
		Arguments: MustMarshalArgs(),
	}
}

func NewSplitPackageCommand(title string, a0 string, a1 string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   SplitPackage.String(),
		Arguments: MustMarshalArgs(a0, a1),
	}
}

func NewStartDebuggingCommand(title string, a0 DebuggingArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   StartDebugging.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewStartProfileCommand(title string, a0 StartProfileArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   StartProfile.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewStopProfileCommand(title string, a0 StopProfileArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   StopProfile.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewTidyCommand(title string, a0 URIArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Tidy.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewUpdateGoSumCommand(title string, a0 URIArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   UpdateGoSum.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewUpgradeDependencyCommand(title string, a0 DependencyArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   UpgradeDependency.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewVendorCommand(title string, a0 URIArg) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Vendor.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewViewsCommand(title string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Views.String(),
		Arguments: MustMarshalArgs(),
	}
}

func NewVulncheckCommand(title string, a0 VulncheckArgs) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   Vulncheck.String(),
		Arguments: MustMarshalArgs(a0),
	}
}

func NewWorkspaceStatsCommand(title string) *protocol.Command {
	return &protocol.Command{
		Title:     title,
		Command:   WorkspaceStats.String(),
		Arguments: MustMarshalArgs(),
	}
}


================================================
FILE: gopls/internal/protocol/command/commandmeta/meta.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package commandmeta provides metadata about LSP commands, by
// statically analyzing the command.Interface type.
//
// It is used to generate JSONRPC dispatch and marshaling.
// TODO(adonovan): combine with gopls/internal/protocol/command/gen.
package commandmeta

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"reflect"
	"slices"
	"strings"
	"unicode"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/packages"
	// (does not depend on gopls itself)
)

// A Command describes a workspace/executeCommand extension command.
type Command struct {
	MethodName string // e.g. "RunTests"
	Name       string // e.g. "gopls.run_tests"
	Title      string
	Doc        string
	Args       []*Field
	Result     *Field
}

type Field struct {
	Name     string
	Doc      string
	JSONTag  string
	Type     types.Type
	FieldMod string
	// In some circumstances, we may want to recursively load additional field
	// descriptors for fields of struct types, documenting their internals.
	Fields []*Field
}

// Load returns a description of the workspace/executeCommand commands
// supported by gopls based on static analysis of the command.Interface type.
func Load() ([]*Command, error) {
	pkgs, err := packages.Load(
		&packages.Config{
			Mode:       packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedImports | packages.NeedDeps,
			BuildFlags: []string{"-tags=generate"},
		},
		"golang.org/x/tools/gopls/internal/protocol/command",
	)
	if err != nil {
		return nil, fmt.Errorf("packages.Load: %v", err)
	}
	pkg := pkgs[0]
	if len(pkg.Errors) > 0 {
		return nil, pkg.Errors[0]
	}

	// command.Interface
	obj := pkg.Types.Scope().Lookup("Interface").Type().Underlying().(*types.Interface)

	// Load command metadata corresponding to each interface method.
	var commands []*Command
	loader := fieldLoader{make(map[types.Object]*Field)}
	for m := range obj.Methods() {
		c, err := loader.loadMethod(pkg, m)
		if err != nil {
			return nil, fmt.Errorf("loading %s: %v", m.Name(), err)
		}
		commands = append(commands, c)
	}

	// Sort commands for deterministic results.
	slices.SortFunc(commands, func(a, b *Command) int {
		return strings.Compare(a.Name, b.Name)
	})
	return commands, nil
}

// fieldLoader loads field information, memoizing results to prevent infinite
// recursion.
type fieldLoader struct {
	loaded map[types.Object]*Field
}

var universeError = types.Universe.Lookup("error").Type()

func (l *fieldLoader) loadMethod(pkg *packages.Package, m *types.Func) (*Command, error) {
	node, err := findField(pkg, m.Pos())
	if err != nil {
		return nil, err
	}
	title, doc := splitDoc(node.Doc.Text())
	c := &Command{
		MethodName: m.Name(),
		Name:       lspName(m.Name()),
		Doc:        doc,
		Title:      title,
	}
	sig := m.Type().Underlying().(*types.Signature)
	rlen := sig.Results().Len()
	if rlen > 2 || rlen == 0 {
		return nil, fmt.Errorf("must have 1 or 2 returns, got %d", rlen)
	}
	finalResult := sig.Results().At(rlen - 1)
	if !types.Identical(finalResult.Type(), universeError) {
		return nil, fmt.Errorf("final return must be error")
	}
	if rlen == 2 {
		obj := sig.Results().At(0)
		c.Result, err = l.loadField(pkg, obj, "", "")
		if err != nil {
			return nil, err
		}
	}
	for i := 0; i < sig.Params().Len(); i++ {
		obj := sig.Params().At(i)
		fld, err := l.loadField(pkg, obj, "", "")
		if err != nil {
			return nil, err
		}
		if i == 0 {
			// Lazy check that the first argument is a context. We could relax this,
			// but then the generated code gets more complicated.
			if named, ok := types.Unalias(fld.Type).(*types.Named); !ok || named.Obj().Name() != "Context" || named.Obj().Pkg().Path() != "context" {
				return nil, fmt.Errorf("first method parameter must be context.Context")
			}
			// Skip the context argument, as it is implied.
			continue
		}
		c.Args = append(c.Args, fld)
	}
	return c, nil
}

func (l *fieldLoader) loadField(pkg *packages.Package, obj *types.Var, doc, tag string) (*Field, error) {
	if existing, ok := l.loaded[obj]; ok {
		return existing, nil
	}
	fld := &Field{
		Name:    obj.Name(),
		Doc:     strings.TrimSpace(doc),
		Type:    obj.Type(),
		JSONTag: reflect.StructTag(tag).Get("json"),
	}

	// This must be done here to handle nested types, such as:
	//
	//    type Test struct { Subtests []Test }
	l.loaded[obj] = fld

	under := fld.Type.Underlying()
	// Quick-and-dirty handling for various underlying types.
	switch p := under.(type) {
	case *types.Pointer:
		under = p.Elem().Underlying()
	case *types.Array:
		under = p.Elem().Underlying()
		fld.FieldMod = fmt.Sprintf("[%d]", p.Len())
	case *types.Slice:
		under = p.Elem().Underlying()
		fld.FieldMod = "[]"
	}

	if s, ok := under.(*types.Struct); ok {
		for i := 0; i < s.NumFields(); i++ {
			obj2 := s.Field(i)
			pkg2 := pkg
			if obj2.Pkg() != pkg2.Types {
				pkg2, ok = pkg.Imports[obj2.Pkg().Path()]
				if !ok {
					return nil, fmt.Errorf("missing import for %q: %q", pkg.ID, obj2.Pkg().Path())
				}
			}
			node, err := findField(pkg2, obj2.Pos())
			if err != nil {
				return nil, err
			}
			tag := s.Tag(i)
			structField, err := l.loadField(pkg2, obj2, node.Doc.Text(), tag)
			if err != nil {
				return nil, err
			}
			fld.Fields = append(fld.Fields, structField)
		}
	}
	return fld, nil
}

// splitDoc parses a command doc string to separate the title from normal
// documentation.
//
// The doc comment should be of the form: "MethodName: Title\nDocumentation"
func splitDoc(text string) (title, doc string) {
	docParts := strings.SplitN(text, "\n", 2)
	titleParts := strings.SplitN(docParts[0], ":", 2)
	if len(titleParts) > 1 {
		title = strings.TrimSpace(titleParts[1])
	}
	if len(docParts) > 1 {
		doc = strings.TrimSpace(docParts[1])
	}
	return title, doc
}

// lspName returns the normalized command name to use in the LSP.
func lspName(methodName string) string {
	words := splitCamel(methodName)
	for i := range words {
		words[i] = strings.ToLower(words[i])
	}
	return "gopls." + strings.Join(words, "_")
}

// splitCamel splits s into words, according to camel-case word boundaries.
// Initialisms are grouped as a single word.
//
// For example:
//
//	"RunTests"      -> []string{"Run", "Tests"}
//	"ClientOpenURL" -> []string{"Client", "Open", "URL"}
func splitCamel(s string) []string {
	var words []string
	for len(s) > 0 {
		last := max(strings.LastIndexFunc(s, unicode.IsUpper), 0)
		if last == len(s)-1 {
			// Group initialisms as a single word.
			last = 1 + strings.LastIndexFunc(s[:last], func(r rune) bool { return !unicode.IsUpper(r) })
		}
		words = append(words, s[last:])
		s = s[:last]
	}
	for i := 0; i < len(words)/2; i++ {
		j := len(words) - i - 1
		words[i], words[j] = words[j], words[i]
	}
	return words
}

// findField finds the struct field or interface method positioned at pos,
// within the AST.
func findField(pkg *packages.Package, pos token.Pos) (*ast.Field, error) {
	fset := pkg.Fset
	var file *ast.File
	for _, f := range pkg.Syntax {
		if fset.File(f.FileStart).Name() == fset.File(pos).Name() {
			file = f
			break
		}
	}
	if file == nil {
		return nil, fmt.Errorf("no file for pos %v", pos)
	}
	path, _ := astutil.PathEnclosingInterval(file, pos, pos)
	// This is fragile, but in the cases we care about, the field will be in
	// path[1].
	return path[1].(*ast.Field), nil
}


================================================
FILE: gopls/internal/protocol/command/gen/gen.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gen is used to generate command bindings from the gopls command
// interface.
package gen

import (
	"bytes"
	"fmt"
	"go/types"
	"log"
	"text/template"

	"golang.org/x/tools/gopls/internal/protocol/command/commandmeta"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/typesinternal"
)

const src = `// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Don't include this file during code generation, or it will break the build
// if existing interface methods have been modified.
//go:build !generate
// +build !generate

// Code generated by gen.go from gopls/internal/protocol/command. DO NOT EDIT.

package command

import (
	{{range $k, $v := .Imports -}}
	"{{$k}}"
	{{end}}
)

// Symbolic names for gopls commands, corresponding to methods of [Interface].
//
// The string value is used in the Command field of protocol.Command.
// These commands may be obtained from a CodeLens or CodeAction request
// and executed by an ExecuteCommand request.
const (
{{- range .Commands}}
	{{.MethodName}} Command = "{{.Name}}"
{{- end}}
)

var Commands = []Command {
{{- range .Commands}}
	{{.MethodName}},
{{- end}}
}

func Dispatch(ctx context.Context, params *protocol.ExecuteCommandParams, s Interface) (any, error) {
	switch Command(params.Command) {
	{{- range .Commands}}
	case {{.MethodName}}:
		{{- if .Args -}}
			{{- range $i, $v := .Args}}
		var a{{$i}} {{typeString $v.Type}}
			{{- end}}
		if err := UnmarshalArgs(params.Arguments{{range $i, $v := .Args}}, &a{{$i}}{{end}}); err != nil {
			return nil, err
		}
		{{end -}}
		return {{if not .Result}}nil, {{end}}s.{{.MethodName}}(ctx{{range $i, $v := .Args}}, a{{$i}}{{end}})
	{{- end}}
	}
	return nil, fmt.Errorf("unsupported command %q", params.Command)
}
{{- range .Commands}}

{{if fallible .Args}}
func New{{.MethodName}}Command(title string, {{range $i, $v := .Args}}{{if $i}}, {{end}}a{{$i}} {{typeString $v.Type}}{{end}}) (*protocol.Command, error) {
	args, err := MarshalArgs({{range $i, $v := .Args}}{{if $i}}, {{end}}a{{$i}}{{end}})
	if err != nil {
		return nil, err
	}
	return &protocol.Command{
		Title: title,
		Command: {{.MethodName}}.String(),
		Arguments: args,
	}, nil
}
{{else}}
func New{{.MethodName}}Command(title string, {{range $i, $v := .Args}}{{if $i}}, {{end}}a{{$i}} {{typeString $v.Type}}{{end}}) *protocol.Command {
	return &protocol.Command{
		Title: title,
		Command: {{.MethodName}}.String(),
		Arguments: MustMarshalArgs({{range $i, $v := .Args}}{{if $i}}, {{end}}a{{$i}}{{end}}),
	}
}
{{end}}

{{end}}
`

type data struct {
	Imports  map[string]bool
	Commands []*commandmeta.Command
}

// Generate computes the new contents of ../command_gen.go from a
// static analysis of the command.Interface type.
func Generate() ([]byte, error) {
	cmds, err := commandmeta.Load()
	if err != nil {
		return nil, fmt.Errorf("loading command data: %v", err)
	}
	const thispkg = "golang.org/x/tools/gopls/internal/protocol/command"
	qual := func(p *types.Package) string {
		if p.Path() == thispkg {
			return ""
		}
		return p.Name()
	}
	tmpl, err := template.New("").Funcs(template.FuncMap{
		"typeString": func(t types.Type) string {
			return types.TypeString(t, qual)
		},
		"fallible": func(args []*commandmeta.Field) bool {
			var fallible func(types.Type) bool
			fallible = func(t types.Type) bool {
				switch t := t.Underlying().(type) {
				case *types.Basic:
					return false
				case *types.Slice:
					return fallible(t.Elem())
				case *types.Struct:
					for field := range t.Fields() {
						if fallible(field.Type()) {
							return true
						}
					}
					return false
				}
				// Assume all other types are fallible for now:
				log.Println("Command.Args has fallible type", t)
				return true
			}
			for _, arg := range args {
				if fallible(arg.Type) {
					return true
				}
			}
			return false
		},
	}).Parse(src)
	if err != nil {
		return nil, err
	}
	d := data{
		Commands: cmds,
		Imports: map[string]bool{
			"context": true,
			"fmt":     true,
			"golang.org/x/tools/gopls/internal/protocol": true,
		},
	}
	for _, c := range d.Commands {
		for _, arg := range c.Args {
			pth := pkgPath(arg.Type)
			if pth != "" && pth != thispkg {
				d.Imports[pth] = true
			}
		}
		if c.Result != nil {
			pth := pkgPath(c.Result.Type)
			if pth != "" && pth != thispkg {
				d.Imports[pth] = true
			}
		}
	}

	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, d); err != nil {
		return nil, fmt.Errorf("executing: %v", err)
	}

	opts := &imports.Options{
		AllErrors:  true,
		FormatOnly: true,
		Comments:   true,
	}
	content, err := imports.Process("", buf.Bytes(), opts)
	if err != nil {
		return nil, fmt.Errorf("goimports: %v", err)
	}
	return content, nil
}

func pkgPath(t types.Type) string {
	if tname := typesinternal.TypeNameFor(t); tname != nil {
		if pkg := tname.Pkg(); pkg != nil {
			return pkg.Path()
		}
	}
	return ""
}


================================================
FILE: gopls/internal/protocol/command/generate.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The generate command generates command_gen.go from a combination of
// static and dynamic analysis of the command package.
package main

import (
	"log"
	"os"

	"golang.org/x/tools/gopls/internal/protocol/command/gen"
)

func main() {
	content, err := gen.Generate()
	if err != nil {
		log.Fatal(err)
	}
	if err := os.WriteFile("command_gen.go", content, 0644); err != nil {
		log.Fatal(err)
	}
}


================================================
FILE: gopls/internal/protocol/command/interface.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run -tags=generate generate.go

// Package command defines the interface provided by gopls for the
// workspace/executeCommand LSP request.
//
// This interface is fully specified by the Interface type, provided it
// conforms to the restrictions outlined in its doc string.
//
// Bindings for server-side command dispatch and client-side serialization are
// also provided by this package, via code generation.
package command

import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/vulncheck"
)

// Interface defines the interface gopls exposes for the
// workspace/executeCommand request.
//
// This interface is used to generate logic for marshaling,
// unmarshaling, and dispatch, so it has some additional restrictions:
//
//  1. All method arguments must be JSON serializable.
//
//  2. Methods must return either error or (T, error), where T is a
//     JSON serializable type.
//
//  3. The first line of the doc string is special.
//     Everything after the colon is considered the command 'Title'.
//     For example:
//
//     Command: Capitalized verb phrase with no period
//
//     Longer description here...
type Interface interface {
	// ApplyFix: Apply a fix
	//
	// Applies a fix to a region of source code.
	ApplyFix(context.Context, ApplyFixArgs) (*protocol.WorkspaceEdit, error)

	// RunTests: Run tests
	//
	// Runs `go test` for a specific set of test or benchmark functions.
	//
	// This command is asynchronous; clients must wait for the 'end' progress notification.
	RunTests(context.Context, RunTestsArgs) error

	// Generate: Run go generate
	//
	// Runs `go generate` for a given directory.
	Generate(context.Context, GenerateArgs) error

	// Doc: Browse package documentation.
	//
	// Opens the Go package documentation page for the current
	// package in a browser.
	Doc(context.Context, DocArgs) (protocol.URI, error)

	// SplitPackage: organize a package into two or more components
	//
	// Opens the "split package" tool in a web browser.
	SplitPackage(ctx context.Context, viewID, packageID string) error

	// RegenerateCgo: Regenerate cgo
	//
	// Regenerates cgo definitions.
	RegenerateCgo(context.Context, URIArg) error

	// Tidy: Run go mod tidy
	//
	// Runs `go mod tidy` for a module.
	Tidy(context.Context, URIArgs) error

	// Vendor: Run go mod vendor
	//
	// Runs `go mod vendor` for a module.
	Vendor(context.Context, URIArg) error

	// EditGoDirective: Run go mod edit -go=version
	//
	// Runs `go mod edit -go=version` for a module.
	EditGoDirective(context.Context, EditGoDirectiveArgs) error

	// UpdateGoSum: Update go.sum
	//
	// Updates the go.sum file for a module.
	UpdateGoSum(context.Context, URIArgs) error

	// CheckUpgrades: Check for upgrades
	//
	// Checks for module upgrades.
	CheckUpgrades(context.Context, CheckUpgradesArgs) error

	// AddDependency: Add a dependency
	//
	// Adds a dependency to the go.mod file for a module.
	AddDependency(context.Context, DependencyArgs) error

	// UpgradeDependency: Upgrade a dependency
	//
	// Upgrades a dependency in the go.mod file for a module.
	UpgradeDependency(context.Context, DependencyArgs) error

	// RemoveDependency: Remove a dependency
	//
	// Removes a dependency from the go.mod file of a module.
	RemoveDependency(context.Context, RemoveDependencyArgs) error

	// ResetGoModDiagnostics: Reset go.mod diagnostics
	//
	// Reset diagnostics in the go.mod file of a module.
	ResetGoModDiagnostics(context.Context, ResetGoModDiagnosticsArgs) error

	// GoGetPackage: 'go get' a package
	//
	// Runs `go get` to fetch a package.
	GoGetPackage(context.Context, GoGetPackageArgs) error

	// GCDetails: Toggle display of compiler optimization details
	//
	// Toggle the per-package flag that causes Go compiler
	// optimization decisions to be reported as diagnostics.
	//
	// (The name is a legacy of a time when the Go compiler was
	// known as "gc". Renaming the command would break custom
	// client-side logic in VS Code.)
	GCDetails(context.Context, protocol.DocumentURI) error

	// LSP is a command that functions as a generic dispatcher, allowing clients
	// to execute any LSP RPC through the "workspace/executeCommand" request.
	//
	// This serves two primary purposes:
	//
	// 1. It provides a unified endpoint for clients that are restricted from
	//    making arbitrary LSP calls directly, giving them full access to the
	//    server's capabilities.
	//
	// 2. It allows the client and server to extend the standard protocol. A
	//    client can send custom parameters that are not part of the official
	//    LSP, enabling richer functionality.
	//
	// The command takes the target LSP method name and its parameters as a
	// [json.RawMessage], routing the call to the appropriate internal handler.
	LSP(context.Context, LSPArgs) (any, error)

	// ListKnownPackages: List known packages
	//
	// Retrieve a list of packages that are importable from the given URI.
	ListKnownPackages(context.Context, URIArg) (ListKnownPackagesResult, error)

	// ListImports: List imports of a file and its package
	//
	// Retrieve a list of imports in the given Go file, and the package it
	// belongs to.
	ListImports(context.Context, URIArg) (ListImportsResult, error)

	// AddImport: Add an import
	//
	// Ask the server to add an import path to a given Go file.  The method will
	// call applyEdit on the client so that clients don't have to apply the edit
	// themselves.
	AddImport(context.Context, AddImportArgs) error

	// ExtractToNewFile: Move selected declarations to a new file
	//
	// Used by the code action of the same name.
	ExtractToNewFile(context.Context, protocol.Location) error

	// StartDebugging: Start the gopls debug server
	//
	// Start the gopls debug server if it isn't running, and return the debug
	// address.
	StartDebugging(context.Context, DebuggingArgs) (DebuggingResult, error)

	// StartProfile: Start capturing a profile of gopls' execution
	//
	// Start a new pprof profile. Before using the resulting file, profiling must
	// be stopped with a corresponding call to StopProfile.
	//
	// This command is intended for internal use only, by the gopls benchmark
	// runner.
	StartProfile(context.Context, StartProfileArgs) (StartProfileResult, error)

	// StopProfile: Stop an ongoing profile
	//
	// This command is intended for internal use only, by the gopls benchmark
	// runner.
	StopProfile(context.Context, StopProfileArgs) (StopProfileResult, error)

	// GoVulncheck: run vulncheck synchronously.
	//
	// Run vulnerability check (`govulncheck`).
	//
	// This command is synchronous, and returns the govulncheck result.
	Vulncheck(context.Context, VulncheckArgs) (VulncheckResult, error)

	// RunGovulncheck: Run vulncheck asynchronously.
	//
	// Run vulnerability check (`govulncheck`).
	//
	// This command is asynchronous; clients must wait for the 'end' progress
	// notification and then retrieve results using gopls.fetch_vulncheck_result.
	//
	// Deprecated: clients should call gopls.vulncheck instead, which returns the
	// actual vulncheck result.
	RunGovulncheck(context.Context, VulncheckArgs) (RunVulncheckResult, error)

	// FetchVulncheckResult: Get known vulncheck result
	//
	// Fetch the result of latest vulnerability check (`govulncheck`).
	//
	// Deprecated: clients should call gopls.vulncheck instead, which returns the
	// actual vulncheck result.
	FetchVulncheckResult(context.Context, URIArg) (map[protocol.DocumentURI]*vulncheck.Result, error)

	// MemStats: Fetch memory statistics
	//
	// Call runtime.GC multiple times and return memory statistics as reported by
	// runtime.MemStats.
	//
	// This command is used for benchmarking, and may change in the future.
	MemStats(context.Context) (MemStatsResult, error)

	// WorkspaceStats: Fetch workspace statistics
	//
	// Query statistics about workspace builds, modules, packages, and files.
	//
	// This command is intended for internal use only, by the gopls stats
	// command.
	WorkspaceStats(context.Context) (WorkspaceStatsResult, error)

	// RunGoWorkCommand: Run `go work [args...]`, and apply the resulting go.work
	// edits to the current go.work file
	RunGoWorkCommand(context.Context, RunGoWorkArgs) error

	// AddTelemetryCounters: Update the given telemetry counters
	//
	// Gopls will prepend "fwd/" to all the counters updated using this command
	// to avoid conflicts with other counters gopls collects.
	AddTelemetryCounters(context.Context, AddTelemetryCountersArgs) error

	// AddTest: add test for the selected function
	AddTest(context.Context, protocol.Location) (*protocol.WorkspaceEdit, error)

	// MaybePromptForTelemetry: Prompt user to enable telemetry
	//
	// Checks for the right conditions, and then prompts the user
	// to ask if they want to enable Go telemetry uploading. If
	// the user responds 'Yes', the telemetry mode is set to "on".
	MaybePromptForTelemetry(context.Context) error

	// ChangeSignature: Perform a "change signature" refactoring
	//
	// This command is experimental, currently only supporting parameter removal.
	// Its signature will certainly change in the future (pun intended).
	ChangeSignature(context.Context, ChangeSignatureArgs) (*protocol.WorkspaceEdit, error)

	// DiagnoseFiles: Cause server to publish diagnostics for the specified files.
	//
	// This command is needed by the 'gopls {check,fix}' CLI subcommands.
	DiagnoseFiles(context.Context, DiagnoseFilesArgs) error

	// Views: List current Views on the server.
	//
	// This command is intended for use by gopls tests only.
	Views(context.Context) ([]View, error)

	// FreeSymbols: Browse free symbols referenced by the selection in a browser.
	//
	// This command is a query over a selected range of Go source
	// code. It reports the set of "free" symbols of the
	// selection: the set of symbols that are referenced within
	// the selection but are declared outside of it. This
	// information is useful for understanding at a glance what a
	// block of code depends on, perhaps as a precursor to
	// extracting it into a separate function.
	FreeSymbols(ctx context.Context, viewID string, loc protocol.Location) error

	// Assembly: Browse assembly listing of current function in a browser.
	//
	// This command opens a web-based disassembly listing of the
	// specified function symbol (plus any nested lambdas and defers).
	// The machine architecture is determined by the view.
	Assembly(_ context.Context, viewID, packageID, symbol string) error

	// ClientOpenURL: Request that the client open a URL in a browser.
	ClientOpenURL(_ context.Context, url string) error

	// ScanImports: force a synchronous scan of the imports cache.
	//
	// This command is intended for use by gopls tests only.
	ScanImports(context.Context) error

	// Packages: Return information about packages
	//
	// This command returns an empty result if the specified files
	// or directories are not associated with any Views on the
	// server yet.
	Packages(context.Context, PackagesArgs) (PackagesResult, error)

	// Modules: Return information about modules within a directory
	//
	// This command returns an empty result if there is no module, or if module
	// mode is disabled. Modules will not cause any new views to be loaded and
	// will only return modules associated with views that have already been
	// loaded, regardless of how it is called. Given current usage (by the
	// language server client), there should never be a case where Modules is
	// called on a path that has not already been loaded.
	Modules(context.Context, ModulesArgs) (ModulesResult, error)

	// PackageSymbols: Return information about symbols in the given file's package.
	PackageSymbols(context.Context, PackageSymbolsArgs) (PackageSymbolsResult, error)

	// ModifyTags: Add or remove struct tags on a given node.
	ModifyTags(context.Context, ModifyTagsArgs) error

	// MoveType: Move a type declaration to a different package.
	MoveType(context.Context, MoveTypeArgs) error
}

type RunTestsArgs struct {
	// The test file containing the tests to run.
	URI protocol.DocumentURI

	// Specific test names to run, e.g. TestFoo.
	Tests []string

	// Specific benchmarks to run, e.g. BenchmarkFoo.
	Benchmarks []string
}

type GenerateArgs struct {
	// URI for the directory to generate.
	Dir protocol.DocumentURI

	// Whether to generate recursively (go generate ./...)
	Recursive bool
}

type DocArgs struct {
	Location     protocol.Location
	ShowDocument bool // in addition to returning the URL, send showDocument
}

// TODO(rFindley): document the rest of these once the docgen is fleshed out.

type ApplyFixArgs struct {
	// The name of the fix to apply.
	//
	// For fixes suggested by analyzers, this is a string constant
	// advertised by the analyzer that matches the Category of
	// the analysis.Diagnostic with a SuggestedFix containing no edits.
	//
	// For fixes suggested by code actions, this is a string agreed
	// upon by the code action and golang.ApplyFix.
	Fix string

	// The portion of the document to fix.
	Location protocol.Location

	// Whether to resolve and return the edits.
	ResolveEdits bool
}

type URIArg struct {
	// The file URI.
	URI protocol.DocumentURI
}

type URIArgs struct {
	// The file URIs.
	URIs []protocol.DocumentURI
}

type CheckUpgradesArgs struct {
	// The go.mod file URI.
	URI protocol.DocumentURI
	// The modules to check.
	Modules []string
}

type DependencyArgs struct {
	// The go.mod file URI.
	URI protocol.DocumentURI
	// Additional args to pass to the go command.
	GoCmdArgs []string
	// Whether to add a require directive.
	AddRequire bool
}

type RemoveDependencyArgs struct {
	// The go.mod file URI.
	URI protocol.DocumentURI
	// The module path to remove.
	ModulePath string
	// If the module is tidied apart from the one unused diagnostic, we can
	// run `go get module@none`, and then run `go mod tidy`. Otherwise, we
	// must make textual edits.
	OnlyDiagnostic bool
}

type EditGoDirectiveArgs struct {
	// Any document URI within the relevant module.
	URI protocol.DocumentURI
	// The version to pass to `go mod edit -go`.
	Version string
}

type GoGetPackageArgs struct {
	// Any document URI within the relevant module.
	URI protocol.DocumentURI
	// The package to go get.
	Pkg        string
	AddRequire bool
}

type AddImportArgs struct {
	// ImportPath is the target import path that should
	// be added to the URI file
	ImportPath string
	// URI is the file that the ImportPath should be
	// added to
	URI protocol.DocumentURI
}

type ListKnownPackagesResult struct {
	// Packages is a list of packages relative
	// to the URIArg passed by the command request.
	// In other words, it omits paths that are already
	// imported or cannot be imported due to compiler
	// restrictions.
	Packages []string
}

type ListImportsResult struct {
	// Imports is a list of imports in the requested file.
	Imports []FileImport

	// PackageImports is a list of all imports in the requested file's package.
	PackageImports []PackageImport
}

type FileImport struct {
	// Path is the import path of the import.
	Path string
	// Name is the name of the import, e.g. `foo` in `import foo "strings"`.
	Name string
}

type PackageImport struct {
	// Path is the import path of the import.
	Path string
}

type DebuggingArgs struct {
	// Optional: the address (including port) for the debug server to listen on.
	// If not provided, the debug server will bind to "localhost:0", and the
	// full debug URL will be contained in the result.
	//
	// If there is more than one gopls instance along the serving path (i.e. you
	// are using a daemon), each gopls instance will attempt to start debugging.
	// If Addr specifies a port, only the daemon will be able to bind to that
	// port, and each intermediate gopls instance will fail to start debugging.
	// For this reason it is recommended not to specify a port (or equivalently,
	// to specify ":0").
	//
	// If the server was already debugging this field has no effect, and the
	// result will contain the previously configured debug URL(s).
	Addr string
}

type DebuggingResult struct {
	// The URLs to use to access the debug servers, for all gopls instances in
	// the serving path. For the common case of a single gopls instance (i.e. no
	// daemon), this will be exactly one address.
	//
	// In the case of one or more gopls instances forwarding the LSP to a daemon,
	// URLs will contain debug addresses for each server in the serving path, in
	// serving order. The daemon debug address will be the last entry in the
	// slice. If any intermediate gopls instance fails to start debugging, no
	// error will be returned but the debug URL for that server in the URLs slice
	// will be empty.
	URLs []string
}

// StartProfileArgs holds the arguments to the StartProfile command.
//
// It is a placeholder for future compatibility.
type StartProfileArgs struct {
}

// StartProfileResult holds the result of the StartProfile command.
//
// It is a placeholder for future compatibility.
type StartProfileResult struct {
}

// StopProfileArgs holds the arguments to the StopProfile command.
//
// It is a placeholder for future compatibility.
type StopProfileArgs struct {
}

// StopProfileResult holds the result to the StopProfile command.
type StopProfileResult struct {
	// File is the profile file name.
	File string
}

type ResetGoModDiagnosticsArgs struct {
	URIArg

	// Optional: source of the diagnostics to reset.
	// If not set, all resettable go.mod diagnostics will be cleared.
	DiagnosticSource string
}

type VulncheckArgs struct {
	// Any document in the directory from which govulncheck will run.
	URI protocol.DocumentURI

	// Package pattern. E.g. "", ".", "./...".
	Pattern string

	// TODO: -tests
}

// RunVulncheckResult holds the result of asynchronously starting the vulncheck
// command.
type RunVulncheckResult struct {
	// Token holds the progress token for LSP workDone reporting of the vulncheck
	// invocation.
	Token protocol.ProgressToken
}

// VulncheckResult holds the result of synchronously running the vulncheck
// command.
type VulncheckResult struct {
	// Result holds the result of running vulncheck.
	Result *vulncheck.Result
	// Token holds the progress token used to report progress during back to the
	// LSP client during vulncheck execution.
	Token protocol.ProgressToken
}

// MemStatsResult holds selected fields from runtime.MemStats.
type MemStatsResult struct {
	HeapAlloc  uint64
	HeapInUse  uint64
	TotalAlloc uint64
}

// WorkspaceStatsResult returns information about the size and shape of the
// workspace.
type WorkspaceStatsResult struct {
	Files FileStats   // file stats for the cache
	Views []ViewStats // stats for each view in the session
}

// FileStats holds information about a set of files.
type FileStats struct {
	Total   int // total number of files
	Largest int // number of bytes in the largest file
	Errs    int // number of files that could not be read
}

// ViewStats holds information about a single View in the session.
type ViewStats struct {
	GoCommandVersion  string       // version of the Go command resolved for this view
	AllPackages       PackageStats // package info for all packages (incl. dependencies)
	WorkspacePackages PackageStats // package info for workspace packages
	Diagnostics       int          // total number of diagnostics in the workspace
}

// PackageStats holds information about a collection of packages.
type PackageStats struct {
	Packages        int // total number of packages
	LargestPackage  int // number of files in the largest package
	CompiledGoFiles int // total number of compiled Go files across all packages
	Modules         int // total number of unique modules
}

type RunGoWorkArgs struct {
	ViewID    string   // ID of the view to run the command from
	InitFirst bool     // Whether to run `go work init` first
	Args      []string // Args to pass to `go work`
}

// AddTelemetryCountersArgs holds the arguments to the AddCounters command
// that updates the telemetry counters.
type AddTelemetryCountersArgs struct {
	// Names and Values must have the same length.
	Names  []string // Name of counters.
	Values []int64  // Values added to the corresponding counters. Must be non-negative.
}

// ChangeSignatureArgs specifies a "change signature" refactoring to perform.
//
// The new signature is expressed via the NewParams and NewResults fields. The
// elements of these lists each describe a new field of the signature, by
// either referencing a field in the old signature or by defining a new field:
//   - If the element is an integer, it references a positional parameter in the
//     old signature.
//   - If the element is a string, it is parsed as a new field to add.
//
// Suppose we have a function `F(a, b int) (string, error)`. Here are some
// examples of refactoring this signature in practice, eliding the 'Location'
// and 'ResolveEdits' fields.
//   - `{ "NewParams": [0], "NewResults": [0, 1] }` removes the second parameter
//   - `{ "NewParams": [1, 0], "NewResults": [0, 1] }` flips the parameter order
//   - `{ "NewParams": [0, 1, "a int"], "NewResults": [0, 1] }` adds a new field
//   - `{ "NewParams": [1, 2], "NewResults": [1] }` drops the `error` result
type ChangeSignatureArgs struct {
	// Location is any range inside the function signature. By convention, this
	// is the same location provided in the codeAction request.
	Location protocol.Location // a range inside of the function signature, as passed to CodeAction

	// NewParams describes parameters of the new signature.
	// An int value references a parameter in the old signature by index.
	// A string value describes a new parameter field (e.g. "x int").
	NewParams []ChangeSignatureParam

	// NewResults describes results of the new signature (see above).
	// An int value references a result in the old signature by index.
	// A string value describes a new result field (e.g. "err error").
	NewResults []ChangeSignatureParam

	// Whether to resolve and return the edits.
	ResolveEdits bool
}

// ChangeSignatureParam implements the API described in the doc string of
// [ChangeSignatureArgs]: a union of JSON int | string.
type ChangeSignatureParam struct {
	OldIndex int
	NewField string
}

func (a *ChangeSignatureParam) UnmarshalJSON(b []byte) error {
	var s string
	if err := json.Unmarshal(b, &s); err == nil {
		a.NewField = s
		return nil
	}
	var i int
	if err := json.Unmarshal(b, &i); err == nil {
		a.OldIndex = i
		return nil
	}
	return fmt.Errorf("must be int or string")
}

func (a ChangeSignatureParam) MarshalJSON() ([]byte, error) {
	if a.NewField != "" {
		return json.Marshal(a.NewField)
	}
	return json.Marshal(a.OldIndex)
}

// DiagnoseFilesArgs specifies a set of files for which diagnostics are wanted.
type DiagnoseFilesArgs struct {
	Files []protocol.DocumentURI
}

// A View holds summary information about a cache.View.
type View struct {
	ID         string               // view ID (the index of this view among all views created)
	Type       string               // view type (via cache.ViewType.String)
	Root       protocol.DocumentURI // root dir of the view (e.g. containing go.mod or go.work)
	Folder     protocol.DocumentURI // workspace folder associated with the view
	EnvOverlay []string             // environment variable overrides
}

// PackagesArgs holds arguments for the Packages command.
type PackagesArgs struct {
	// Files is a list of files and directories whose associated
	// packages should be described by the result.
	//
	// In some cases, a file may belong to more than one package;
	// the result may describe any of them.
	Files []protocol.DocumentURI

	// Enumerate all packages under the directory loadable with
	// the ... pattern.
	// The search does not cross the module boundaries and
	// does not return packages that are not yet loaded.
	// (e.g. those excluded by the gopls directory filter setting,
	// or the go.work configuration)
	Recursive bool `json:"Recursive,omitempty"`

	// Mode controls the types of information returned for each package.
	Mode PackagesMode
}

// PackagesMode controls the details to include in PackagesResult.
type PackagesMode uint64

const (
	// Populate the [TestFile.Tests] field in [Package] returned by the
	// Packages command.
	NeedTests PackagesMode = 1 << iota
)

// PackagesResult is the result of the Packages command.
type PackagesResult struct {
	// Packages is an unordered list of package metadata.
	Packages []Package

	// Module maps module path to module metadata for
	// all the modules of the returned Packages.
	Module map[string]Module
}

// Package describes a Go package (not an empty parent).
type Package struct {
	// Package path.
	Path string
	// Module path. Empty if the package doesn't
	// belong to any module.
	ModulePath string
	// q in a "p [q.test]" package.
	ForTest string

	// Note: the result does not include the directory name
	// of the package because mapping between a package and
	// a folder is not possible in certain build systems.
	// If directory info is needed, one can guess it
	// from the TestFile's file name.

	// TestFiles contains the subset of the files of the package
	// whose name ends with "_test.go".
	// They are ordered deterministically as determined
	// by the underlying build system.
	TestFiles []TestFile
}

type Module struct {
	Path    string               // module path
	Version string               // module version if any.
	GoMod   protocol.DocumentURI // path to the go.mod file.
}

type TestFile struct {
	URI protocol.DocumentURI // a *_test.go file

	// Tests is the list of tests in File, including subtests.
	//
	// The set of subtests is not exhaustive as in general they may be
	// dynamically generated, so it is impossible for static heuristics
	// to enumerate them.
	//
	// Tests are lexically ordered.
	// Since subtest names are prefixed by their top-level test names
	// each top-level test precedes its subtests.
	Tests []TestCase
}

// TestCase represents a test case.
// A test case can be a top-level Test/Fuzz/Benchmark/Example function,
// as recognized by 'go list' or 'go test -list', or
// a subtest within a top-level function.
type TestCase struct {
	// Name is the complete name of the test (Test, Benchmark, Example, or Fuzz)
	// or the subtest as it appears in the output of go test -json.
	// The server may attempt to infer names of subtests by static
	// analysis; if so, it should aim to simulate the actual computed
	// name of the test, including any disambiguating suffix such as "#01".
	// To run only this test, clients need to compute the -run, -bench, -fuzz
	// flag values by first splitting the Name with "/" and
	// quoting each element with "^" + regexp.QuoteMeta(Name) + "$".
	// e.g. TestToplevel/Inner.Subtest → -run=^TestToplevel$/^Inner\.Subtest$
	Name string

	// Loc is the filename and range enclosing this test function
	// or the subtest. This is used to place the gutter marker
	// and group tests based on location.
	// For subtests whose test names can be determined statically,
	// this can be either t.Run or the test data table
	// for table-driven setup.
	// Some testing frameworks allow to declare the actual test
	// logic in a different file. For example, one can define
	// a testify test suite in suite_test.go and use it from
	// main_test.go.
	/*
	   -- main_test.go --
	   ...
	   func TestFoo(t *testing.T) {
	       suite.Run(t, new(MyTestSuite))
	   }
	   -- suite_test.go --
	   type MyTestSuite struct {
	   	suite.Suite
	   }
	   func (suite *MyTestSuite) TestBar() { ... }
	*/
	// In this case, the testing framework creates "TestFoo/TestBar"
	// and the corresponding test case belongs to "main_test.go"
	// TestFile. However, the test case has "suite_test.go" as its
	// file location.
	Loc protocol.Location
}

type ModulesArgs struct {
	// Dir is the directory in which to search for go.mod files.
	Dir protocol.DocumentURI

	// MaxDepth is the directory walk limit.
	// A value of 0 means inspect only Dir.
	// 1 means inspect its child directories too, and so on.
	// A negative value removes the limit.
	MaxDepth int
}

type ModulesResult struct {
	Modules []Module
}

type PackageSymbolsArgs struct {
	URI protocol.DocumentURI
}

type PackageSymbolsResult struct {
	PackageName string
	// Files is a list of files in the given URI's package.
	Files   []protocol.DocumentURI
	Symbols []PackageSymbol
}

// PackageSymbol has the same fields as DocumentSymbol, with an additional int field "File"
// which stores the index of the symbol's file in the PackageSymbolsResult.Files array
type PackageSymbol struct {
	Name string `json:"name"`

	Detail string `json:"detail,omitempty"`

	// protocol.SymbolKind maps an integer to an enum:
	// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#symbolKind
	// i.e. File = 1
	Kind protocol.SymbolKind `json:"kind"`

	Tags []protocol.SymbolTag `json:"tags,omitempty"`

	Range protocol.Range `json:"range"`

	SelectionRange protocol.Range `json:"selectionRange"`

	Children []PackageSymbol `json:"children,omitempty"`

	// Index of this symbol's file in PackageSymbolsResult.Files
	File int `json:"file,omitempty"`
}

// ModifyTagsArgs holds variables that determine how struct tags are modified.
type ModifyTagsArgs struct {
	// NOTE(hxjiang): the mofidication field is important, when resolving a
	// command, the title of the code action or code lenses is no longer available.
	// The language server is not aware of the original user intention, whether
	// the command is meant for tag addition or tag removal.
	Modification         string
	URI                  protocol.DocumentURI // uri of the file to be modified
	Range                protocol.Range       // range in the file for where to modify struct tags
	Add                  string               // comma-separated list of tags to add; i.e. "json,xml"
	AddOptions           string               // comma-separated list of options to add, per tag; i.e. "json=omitempty"
	Remove               string               // comma-separated list of tags to remove
	RemoveOptions        string               // comma-separated list of options to remove
	Clear                bool                 // if set, clear all tags. tags are cleared before any new tags are added
	ClearOptions         bool                 // if set, clear all tag options; options are cleared before any new options are added
	Overwrite            bool                 // if set, replace existing tags when adding
	SkipUnexportedFields bool                 // if set, do not modify tags on unexported struct fields
	Transform            string               // transform rule for adding tags; i.e. "snakecase"
	ValueFormat          string               // format for the tag's value, after transformation; for example "column:{field}"
}

type LSPArgs struct {
	Method string          `json:"method"`
	Param  json.RawMessage `json:"param"`
}

// MoveTypeArgs specifies a "move type" refactoring to perform.
type MoveTypeArgs struct {
	// The location of the type to move.
	Location protocol.Location
	// TODO(mkalil): Determine format of the parameter that specifies where to
	// move the type to.
}


================================================
FILE: gopls/internal/protocol/command/interface_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package command_test

import (
	"os"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol/command/gen"
	"golang.org/x/tools/internal/testenv"
)

// TestGenerated ensures that we haven't forgotten to update command_gen.go.
func TestGenerated(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.NeedsLocalXTools(t)

	onDisk, err := os.ReadFile("command_gen.go")
	if err != nil {
		t.Fatal(err)
	}

	generated, err := gen.Generate()
	if err != nil {
		t.Fatal(err)
	}
	if diff := cmp.Diff(string(generated), string(onDisk)); diff != "" {
		t.Errorf("command_gen.go is stale -- regenerate (-generated +on disk)\n%s", diff)
	}
}


================================================
FILE: gopls/internal/protocol/command/util.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package command

import (
	"encoding/json"
	"fmt"
)

// A Command identifies one of gopls' ad-hoc extension commands
// that may be invoked through LSP's executeCommand.
type Command string

func (c Command) String() string { return string(c) }

// MarshalArgs encodes the given arguments to json.RawMessages. This function
// is used to construct arguments to a protocol.Command.
//
// Example usage:
//
//	jsonArgs, err := MarshalArgs(1, "hello", true, StructuredArg{42, 12.6})
func MarshalArgs(args ...any) ([]json.RawMessage, error) {
	var out []json.RawMessage
	for _, arg := range args {
		argJSON, err := json.Marshal(arg)
		if err != nil {
			return nil, err
		}
		out = append(out, argJSON)
	}
	return out, nil
}

// MustMarshalArgs is like MarshalArgs, but panics on error.
func MustMarshalArgs(args ...any) []json.RawMessage {
	msg, err := MarshalArgs(args...)
	if err != nil {
		panic(err)
	}
	return msg
}

// UnmarshalArgs decodes the given json.RawMessages to the variables provided
// by args. Each element of args should be a pointer.
//
// Example usage:
//
//	var (
//	    num int
//	    str string
//	    bul bool
//	    structured StructuredArg
//	)
//	err := UnmarshalArgs(args, &num, &str, &bul, &structured)
func UnmarshalArgs(jsonArgs []json.RawMessage, args ...any) error {
	if len(args) != len(jsonArgs) {
		return fmt.Errorf("DecodeArgs: expected %d input arguments, got %d JSON arguments", len(args), len(jsonArgs))
	}
	for i, arg := range args {
		if err := json.Unmarshal(jsonArgs[i], arg); err != nil {
			return err
		}
	}
	return nil
}


================================================
FILE: gopls/internal/protocol/context.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"bytes"
	"context"
	"sync"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/label"
	"golang.org/x/tools/internal/xcontext"
)

type contextKey int

const (
	clientKey = contextKey(iota)
)

func WithClient(ctx context.Context, client Client) context.Context {
	return context.WithValue(ctx, clientKey, client)
}

func LogEvent(ctx context.Context, ev core.Event, lm label.Map, mt MessageType) context.Context {
	client, ok := ctx.Value(clientKey).(Client)
	if !ok {
		return ctx
	}
	buf := &bytes.Buffer{}
	p := export.Printer{}
	p.WriteEvent(buf, ev, lm)
	msg := &LogMessageParams{Type: mt, Message: buf.String()}
	// Handle messages generated via event.Error, which won't have a level Label.
	if event.IsError(ev) {
		msg.Type = Error
	}

	// The background goroutine lives forever once started,
	// and ensures log messages are sent in order (#61216).
	startLogSenderOnce.Do(func() {
		go func() {
			for f := range logQueue {
				f()
			}
		}()
	})

	// Add the log item to a queue, rather than sending a
	// window/logMessage request to the client synchronously,
	// which would slow down this thread.
	ctx2 := xcontext.Detach(ctx)
	logQueue <- func() { client.LogMessage(ctx2, msg) }

	return ctx
}

var (
	startLogSenderOnce sync.Once
	logQueue           = make(chan func(), 100) // big enough for a large transient burst
)


================================================
FILE: gopls/internal/protocol/doc.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run ./generate

// Package protocol contains the structs that map directly to the
// request and response messages of the Language Server Protocol.
//
// It is a literal transcription, with unmodified comments, and only the changes
// required to make it go code.
// Names are uppercased to export them.
// All fields have JSON tags added to correct the names.
// Fields marked with a ? are also marked as "omitempty"
// Fields that are "|| null" are made pointers
// Fields that are string or number are left as string
// Fields that are type "number" are made float64
package protocol


================================================
FILE: gopls/internal/protocol/edits.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"fmt"
	"slices"

	"golang.org/x/tools/internal/diff"
)

// EditsFromDiffEdits converts diff.Edits to a non-nil slice of LSP TextEdits.
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textEditArray
func EditsFromDiffEdits(m *Mapper, edits []diff.Edit) ([]TextEdit, error) {
	// LSP doesn't require TextEditArray to be sorted:
	// this is the receiver's concern. But govim, and perhaps
	// other clients have historically relied on the order.
	edits = slices.Clone(edits)
	diff.SortEdits(edits)

	result := make([]TextEdit, len(edits))
	for i, edit := range edits {
		rng, err := m.OffsetRange(edit.Start, edit.End)
		if err != nil {
			return nil, err
		}
		result[i] = TextEdit{
			Range:   rng,
			NewText: edit.New,
		}
	}
	return result, nil
}

// EditsToDiffEdits converts LSP TextEdits to diff.Edits.
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textEditArray
func EditsToDiffEdits(m *Mapper, edits []TextEdit) ([]diff.Edit, error) {
	if edits == nil {
		return nil, nil
	}
	result := make([]diff.Edit, len(edits))
	for i, edit := range edits {
		start, end, err := m.RangeOffsets(edit.Range)
		if err != nil {
			return nil, err
		}
		result[i] = diff.Edit{
			Start: start,
			End:   end,
			New:   edit.NewText,
		}
	}
	return result, nil
}

// ApplyEdits applies the patch (edits) to m.Content and returns the result.
// It also returns the edits converted to diff-package form.
func ApplyEdits(m *Mapper, edits []TextEdit) ([]byte, []diff.Edit, error) {
	diffEdits, err := EditsToDiffEdits(m, edits)
	if err != nil {
		return nil, nil, err
	}
	out, err := diff.ApplyBytes(m.Content, diffEdits)
	return out, diffEdits, err
}

// AsTextEdits converts a slice possibly containing AnnotatedTextEdits
// to a slice of TextEdits.
func AsTextEdits(edits []Or_TextDocumentEdit_edits_Elem) []TextEdit {
	var result []TextEdit
	for _, e := range edits {
		var te TextEdit
		if x, ok := e.Value.(AnnotatedTextEdit); ok {
			te = x.TextEdit
		} else if x, ok := e.Value.(TextEdit); ok {
			te = x
		} else {
			panic(fmt.Sprintf("unexpected type %T, expected AnnotatedTextEdit or TextEdit", e.Value))
		}
		result = append(result, te)
	}
	return result
}

// AsAnnotatedTextEdits converts a slice of TextEdits
// to a slice of Or_TextDocumentEdit_edits_Elem.
// (returning a typed nil is required in server: in code_action.go and command.go))
func AsAnnotatedTextEdits(edits []TextEdit) []Or_TextDocumentEdit_edits_Elem {
	if edits == nil {
		return []Or_TextDocumentEdit_edits_Elem{}
	}
	var result []Or_TextDocumentEdit_edits_Elem
	for _, e := range edits {
		result = append(result, Or_TextDocumentEdit_edits_Elem{
			Value: TextEdit{
				Range:   e.Range,
				NewText: e.NewText,
			},
		})
	}
	return result
}

// fileHandle abstracts file.Handle to avoid a cycle.
type fileHandle interface {
	URI() DocumentURI
	Version() int32
}

// NewWorkspaceEdit constructs a WorkspaceEdit from a list of document changes.
//
// Any ChangeAnnotations must be added after.
func NewWorkspaceEdit(changes ...DocumentChange) *WorkspaceEdit {
	return &WorkspaceEdit{DocumentChanges: changes}
}

// DocumentChangeEdit constructs a DocumentChange containing a
// TextDocumentEdit from a file.Handle and a list of TextEdits.
func DocumentChangeEdit(fh fileHandle, textedits []TextEdit) DocumentChange {
	return DocumentChange{
		TextDocumentEdit: &TextDocumentEdit{
			TextDocument: OptionalVersionedTextDocumentIdentifier{
				Version:                fh.Version(),
				TextDocumentIdentifier: TextDocumentIdentifier{URI: fh.URI()},
			},
			Edits: AsAnnotatedTextEdits(textedits),
		},
	}
}

// DocumentChangeCreate constructs a DocumentChange that creates a file.
func DocumentChangeCreate(uri DocumentURI) DocumentChange {
	return DocumentChange{
		CreateFile: &CreateFile{
			Kind: "create",
			URI:  uri,
		},
	}
}

// DocumentChangeDelete constructs a DocumentChange that deletes a file.
func DocumentChangeDelete(uri DocumentURI) DocumentChange {
	return DocumentChange{
		DeleteFile: &DeleteFile{
			Kind: "delete",
			URI:  uri,
		},
	}
}

// DocumentChangeRename constructs a DocumentChange that renames a file.
func DocumentChangeRename(src, dst DocumentURI) DocumentChange {
	return DocumentChange{
		RenameFile: &RenameFile{
			Kind:   "rename",
			OldURI: src,
			NewURI: dst,
		},
	}
}

// SelectCompletionTextEdit returns insert or replace mode TextEdit
// included in the completion item.
func SelectCompletionTextEdit(item CompletionItem, useReplaceMode bool) (TextEdit, error) {
	var edit TextEdit
	switch typ := item.TextEdit.Value.(type) {
	case TextEdit: // old style completion item.
		return typ, nil
	case InsertReplaceEdit:
		if useReplaceMode {
			return TextEdit{
				NewText: typ.NewText,
				Range:   typ.Replace,
			}, nil
		} else {
			return TextEdit{
				NewText: typ.NewText,
				Range:   typ.Insert,
			}, nil
		}
	default:
		return edit, fmt.Errorf("unsupported edit type %T", typ)
	}
}


================================================
FILE: gopls/internal/protocol/enums.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"fmt"
)

// CodeActionUnknownTrigger indicates that the trigger for a
// CodeAction request is unknown. A missing
// CodeActionContext.TriggerKind should be treated as equivalent.
const CodeActionUnknownTrigger CodeActionTriggerKind = 0

var (
	namesTextDocumentSyncKind   [int(Incremental) + 1]string
	namesMessageType            [int(Log) + 1]string
	namesFileChangeType         [int(Deleted) + 1]string
	namesWatchKind              [int(WatchDelete) + 1]string
	namesCompletionTriggerKind  [int(TriggerForIncompleteCompletions) + 1]string
	namesDiagnosticSeverity     [int(SeverityHint) + 1]string
	namesDiagnosticTag          [int(Unnecessary) + 1]string
	namesCompletionItemKind     [int(TypeParameterCompletion) + 1]string
	namesInsertTextFormat       [int(SnippetTextFormat) + 1]string
	namesDocumentHighlightKind  [int(Write) + 1]string
	namesSymbolKind             [int(TypeParameter) + 1]string
	namesTextDocumentSaveReason [int(FocusOut) + 1]string
)

func init() {
	namesTextDocumentSyncKind[int(None)] = "None"
	namesTextDocumentSyncKind[int(Full)] = "Full"
	namesTextDocumentSyncKind[int(Incremental)] = "Incremental"

	namesMessageType[int(Error)] = "Error"
	namesMessageType[int(Warning)] = "Warning"
	namesMessageType[int(Info)] = "Info"
	namesMessageType[int(Log)] = "Log"

	namesFileChangeType[int(Created)] = "Created"
	namesFileChangeType[int(Changed)] = "Changed"
	namesFileChangeType[int(Deleted)] = "Deleted"

	namesWatchKind[int(WatchCreate)] = "WatchCreate"
	namesWatchKind[int(WatchChange)] = "WatchChange"
	namesWatchKind[int(WatchDelete)] = "WatchDelete"

	namesCompletionTriggerKind[int(Invoked)] = "Invoked"
	namesCompletionTriggerKind[int(TriggerCharacter)] = "TriggerCharacter"
	namesCompletionTriggerKind[int(TriggerForIncompleteCompletions)] = "TriggerForIncompleteCompletions"

	namesDiagnosticSeverity[int(SeverityError)] = "Error"
	namesDiagnosticSeverity[int(SeverityWarning)] = "Warning"
	namesDiagnosticSeverity[int(SeverityInformation)] = "Information"
	namesDiagnosticSeverity[int(SeverityHint)] = "Hint"

	namesDiagnosticTag[int(Unnecessary)] = "Unnecessary"

	namesCompletionItemKind[int(TextCompletion)] = "text"
	namesCompletionItemKind[int(MethodCompletion)] = "method"
	namesCompletionItemKind[int(FunctionCompletion)] = "func"
	namesCompletionItemKind[int(ConstructorCompletion)] = "constructor"
	namesCompletionItemKind[int(FieldCompletion)] = "field"
	namesCompletionItemKind[int(VariableCompletion)] = "var"
	namesCompletionItemKind[int(ClassCompletion)] = "type"
	namesCompletionItemKind[int(InterfaceCompletion)] = "interface"
	namesCompletionItemKind[int(ModuleCompletion)] = "package"
	namesCompletionItemKind[int(PropertyCompletion)] = "property"
	namesCompletionItemKind[int(UnitCompletion)] = "unit"
	namesCompletionItemKind[int(ValueCompletion)] = "value"
	namesCompletionItemKind[int(EnumCompletion)] = "enum"
	namesCompletionItemKind[int(KeywordCompletion)] = "keyword"
	namesCompletionItemKind[int(SnippetCompletion)] = "snippet"
	namesCompletionItemKind[int(ColorCompletion)] = "color"
	namesCompletionItemKind[int(FileCompletion)] = "file"
	namesCompletionItemKind[int(ReferenceCompletion)] = "reference"
	namesCompletionItemKind[int(FolderCompletion)] = "folder"
	namesCompletionItemKind[int(EnumMemberCompletion)] = "enumMember"
	namesCompletionItemKind[int(ConstantCompletion)] = "const"
	namesCompletionItemKind[int(StructCompletion)] = "struct"
	namesCompletionItemKind[int(EventCompletion)] = "event"
	namesCompletionItemKind[int(OperatorCompletion)] = "operator"
	namesCompletionItemKind[int(TypeParameterCompletion)] = "typeParam"

	namesInsertTextFormat[int(PlainTextTextFormat)] = "PlainText"
	namesInsertTextFormat[int(SnippetTextFormat)] = "Snippet"

	namesDocumentHighlightKind[int(Text)] = "Text"
	namesDocumentHighlightKind[int(Read)] = "Read"
	namesDocumentHighlightKind[int(Write)] = "Write"

	namesSymbolKind[int(File)] = "File"
	namesSymbolKind[int(Module)] = "Module"
	namesSymbolKind[int(Namespace)] = "Namespace"
	namesSymbolKind[int(Package)] = "Package"
	namesSymbolKind[int(Class)] = "Class"
	namesSymbolKind[int(Method)] = "Method"
	namesSymbolKind[int(Property)] = "Property"
	namesSymbolKind[int(Field)] = "Field"
	namesSymbolKind[int(Constructor)] = "Constructor"
	namesSymbolKind[int(Enum)] = "Enum"
	namesSymbolKind[int(Interface)] = "Interface"
	namesSymbolKind[int(Function)] = "Function"
	namesSymbolKind[int(Variable)] = "Variable"
	namesSymbolKind[int(Constant)] = "Constant"
	namesSymbolKind[int(String)] = "String"
	namesSymbolKind[int(Number)] = "Number"
	namesSymbolKind[int(Boolean)] = "Boolean"
	namesSymbolKind[int(Array)] = "Array"
	namesSymbolKind[int(Object)] = "Object"
	namesSymbolKind[int(Key)] = "Key"
	namesSymbolKind[int(Null)] = "Null"
	namesSymbolKind[int(EnumMember)] = "EnumMember"
	namesSymbolKind[int(Struct)] = "Struct"
	namesSymbolKind[int(Event)] = "Event"
	namesSymbolKind[int(Operator)] = "Operator"
	namesSymbolKind[int(TypeParameter)] = "TypeParameter"

	namesTextDocumentSaveReason[int(Manual)] = "Manual"
	namesTextDocumentSaveReason[int(AfterDelay)] = "AfterDelay"
	namesTextDocumentSaveReason[int(FocusOut)] = "FocusOut"
}

func formatEnum(f fmt.State, i int, names []string, unknown string) {
	s := ""
	if i >= 0 && i < len(names) {
		s = names[i]
	}
	if s != "" {
		fmt.Fprint(f, s)
	} else {
		fmt.Fprintf(f, "%s(%d)", unknown, i)
	}
}

func (e TextDocumentSyncKind) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesTextDocumentSyncKind[:], "TextDocumentSyncKind")
}

func (e MessageType) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesMessageType[:], "MessageType")
}

func (e FileChangeType) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesFileChangeType[:], "FileChangeType")
}

func (e CompletionTriggerKind) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesCompletionTriggerKind[:], "CompletionTriggerKind")
}

func (e DiagnosticSeverity) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesDiagnosticSeverity[:], "DiagnosticSeverity")
}

func (e DiagnosticTag) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesDiagnosticTag[:], "DiagnosticTag")
}

func (e CompletionItemKind) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesCompletionItemKind[:], "CompletionItemKind")
}

func (e InsertTextFormat) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesInsertTextFormat[:], "InsertTextFormat")
}

func (e DocumentHighlightKind) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesDocumentHighlightKind[:], "DocumentHighlightKind")
}

func (e SymbolKind) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesSymbolKind[:], "SymbolKind")
}

func (e TextDocumentSaveReason) Format(f fmt.State, c rune) {
	formatEnum(f, int(e), namesTextDocumentSaveReason[:], "TextDocumentSaveReason")
}


================================================
FILE: gopls/internal/protocol/form.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file defines types for an experimental feature (golang/go#76331,
// microsoft/language-server-protocol#1164). As an experimental feature,
// these types are not yet included in tsprotocol.go.

package protocol

import "encoding/json"

// FormFieldTypeString defines a text input.
//
// It is defined as a struct to allow for future extensibility, such as
// adding regex validation or file URI constraints.
type FormFieldTypeString struct {
	// Kind must be "string".
	Kind string `json:"kind"`
}

// FormFieldTypeDocumentURI defines an input for a file or directory URI.
//
// The client determines the best mechanism to collect this information from
// the user (e.g., a graphical file picker, a text input with autocomplete, etc).
//
// The value returned by the client must be a valid "DocumentUri" as defined
// in the LSP specification:
// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#documentUri
type FormFieldTypeDocumentURI struct {
	// Kind must be "documentURI".
	Kind string `json:"kind"`
}

// FormFieldTypeBool defines a boolean input.
type FormFieldTypeBool struct {
	// Kind must be "bool".
	Kind string `json:"kind"`
}

// FormFieldTypeNumber defines a numeric input.
//
// It is defined as a struct to allow for future extensibility, such as
// adding range constraints (min/max) or precision requirements.
type FormFieldTypeNumber struct {
	// Kind must be "number".
	Kind string `json:"kind"`
}

// FormEnumEntry represents a single option in an enumeration.
type FormEnumEntry struct {
	// Value is the unique string identifier for this option.
	//
	// This is the value that will be sent back to the server in
	// 'FormAnswers' if the user selects this option.
	Value string `json:"value"`

	// Description is the human-readable label presented to the user.
	Description string `json:"description"`
}

// FormFieldTypeEnum defines a selection from a set of values.
//
// Use this type when:
// - The number of options is small (e.g., < 20).
// - All options are known at the time the form is created.
type FormFieldTypeEnum struct {
	// Kind must be "enum".
	Kind string `json:"kind"`

	// Entries is the list of allowable options.
	Entries []FormEnumEntry `json:"entries"`
}

// FormFieldTypeLazyEnum defines a selection from a large or dynamic enum entry set.
//
// Use this type when:
//  1. The dataset is too large to send efficiently in a single payload
//     (e.g., thousands of workspace symbols, file uri or cloud resources).
//  2. The available options depend on the user's input (e.g., semantic search).
//  3. Generating the list is expensive and should only be done if requested.
//
// The client is expected to render a search interface (e.g., a combo box with
// a text input) and query the server via 'interactive/listEnum' as the user types.
type FormFieldTypeLazyEnum struct {
	// Kind must be "lazyEnum".
	Kind string `json:"kind"`

	// TODO(hxjiang): consider make debounce configurable since fetching
	// cloud resources could be expensive and slow.

	// Source identifies the data source on the server.
	//
	// Examples: "workspace/symbol", "database/schema", "git/tags".
	Source string `json:"source"`

	// Config contains the static settings for the source.
	// The client treats this as opaque data and echoes it back in the
	// 'interactive/listEnum' request.
	Config *json.RawMessage `json:"config,omitempty"`
}

// FormFieldTypeList defines a homogenous list of items.
type FormFieldTypeList struct {
	// Kind must be "list".
	Kind string `json:"kind"`

	// ElementType specifies the type of the items in the list.
	// It must be one of the FormFieldType* structs (e.g., FormFieldTypeString).
	ElementType any `json:"elementType"`
}

// FormField describes a single question in a form and its validation state.
type FormField struct {
	// Description is the text content of the question (the prompt) presented
	// to the user.
	Description string `json:"description"`

	// Type specifies the data type and validation constraints for the answer.
	//
	// It must be one of the FormFieldType* structs. The Kind field within the
	// struct determines the expected data type.
	//
	// The language client is expected to render an input appropriate for this
	// type. If the client does not support the specified type, it should
	// fall back to a string input.
	Type any `json:"type"`

	// Default specifies an optional initial value for the answer.
	//
	// If Type is FormFieldTypeEnum, this value must be present in the enum's
	// Values slice.
	Default any `json:"default,omitempty"`

	// Error provides a validation message from the language server.
	// If empty, the current answer is considered valid.
	Error string `json:"error,omitempty"`
}

// InteractiveParams allow the server and client to exchange interactive
// questions and answers during an LSP request.
//
// The server populates FormFields to define the schema. The server may
// optionally populate FormAnswers to preserve previous user input; if
// provided, the client may present these as default values.
//
// When the client responds, it must provide FormAnswers. The client is not
// required to send FormFields back to the server.
type InteractiveParams struct {
	// FormFields defines the questions and validation errors in previous
	// answers to the same questions.
	//
	// This is a server-to-client field. The language server defines these, and
	// the client uses them to render the form.
	//
	// Note: This is a non-standard protocol extension. See microsoft/language-server-protocol#1164.
	FormFields []FormField `json:"formFields,omitempty"`

	// FormAnswers contains the values for the form questions.
	//
	// When sent by the language server, this field is optional but recommended
	// to support editing previous values.
	//
	// When sent by the language client, this field is required. The slice must
	// have the same length as FormFields (one answer per question), where the
	// answer at index i corresponds to the field at index i.
	//
	// Note: This is a non-standard protocol extension. See microsoft/language-server-protocol#1164.
	FormAnswers []any `json:"formAnswers,omitempty"`
}

// InteractiveListEnumParams defines the parameters for the
// 'interactive/listEnum' request.
type InteractiveListEnumParams struct {
	// Source identifies the data source on the server.
	//
	// The client treats this as opaque data and echoes it back in the
	// 'interactive/listEnum' request.
	//
	// Examples: "workspace/symbol", "database/schema", "git/tags".
	Source string `json:"source"`

	// Config contains the static settings for the specified source.
	//
	// The client treats this as opaque data and echoes it back in the
	// 'interactive/listEnum' request.
	Config *json.RawMessage `json:"config,omitempty"`

	// A query string to filter enum entries by.
	//
	// The exact interpretation of this string (e.g., fuzzy matching, exact
	// match, prefix search, or regular expression) is entirely up to the
	// server and may vary depending on the source. This follows the similar
	// semantics as the standard 'workspace/symbol' request. Clients may
	// send an empty string here to request a default set of enum entries.
	Query string `json:"query"`
}


================================================
FILE: gopls/internal/protocol/generate/README.md
================================================
# LSP Support for gopls

## The protocol

The LSP protocol exchanges json-encoded messages between the client and the server.
(gopls is the server.) The messages are either Requests, which require Responses, or
Notifications, which generate no response. Each Request or Notification has a method name
such as "textDocument/hover" that indicates its meaning and determines which function in the server will handle it.
The protocol is described in a
[web page](https://microsoft.github.io/language-server-protocol/specifications/lsp/3.18/specification/),
in words, and in a json file (metaModel.json) available either linked towards the bottom of the
web page, or in the vscode-languageserver-node repository. This code uses the latter so the
exact version can be tied to a githash. By default, the command will download the `github.com/microsoft/vscode-languageserver-node` repository to a temporary directory.

The specification has five sections

1. Requests, which describe the Request and Response types for request methods (e.g., *textDocument/didChange*),
2. Notifications, which describe the Request types for notification methods,
3. Structures, which describe named struct-like types,
4. TypeAliases, which describe type aliases,
5. Enumerations, which describe named constants.

Requests and Notifications are tagged with a Method (e.g., `"textDocument/hover"`).
The specification does not specify the names of the functions that handle the messages. These
names are specified by the `methodNames` map. Enumerations generate Go `const`s, but
in Typescript they are scoped to namespaces, while in Go they are scoped to a package, so the Go names
may need to be modified to avoid name collisions. (See the `disambiguate` map, and its use.)

Finally, the specified types are Typescript types, which are quite different from Go types.

### Optionality

The specification can mark fields in structs as Optional. The client distinguishes between missing
fields and `null` fields in some cases. The Go translation for an optional type
should be making sure the field's value
can be `nil`, and adding the json tag `,omitempty`. The former condition would be satisfied by
adding `*` to the field's type if the type is not a reference type.

### Types

The specification uses a number of different types, only a few of which correspond directly to Go types.
The specification's types are "base", "reference", "map", "literal", "stringLiteral", "tuple", "and", "or".
The "base" types correspond directly to Go types, although some Go types needs to be chosen for `URI` and `DocumentUri`. (The "base" types`RegExp`, `BooleanLiteral`, `NumericLiteral` never occur.)

"reference" types are the struct-like types in the Structures section of the specification. The given
names are suitable for Go to use, except the code needs to change names like `_Initialize` to `XInitialize` so
they are exported for json marshaling and unmarshaling.

"map" types are just like Go. (The key type in all of them is `DocumentUri`.)

"stringLiteral" types are types whose type name and value are a single string. The chosen Go equivalent
is to make the type `string` and the value a constant. (The alternative would be to generate a new
named type, which seemed redundant.)

"literal" types are like Go anonymous structs, so they have to be given a name. (All instances
of the remaining types have to be given names. One approach is to construct the name from the components
of the type, but this leads to misleading punning, and is unstable if components are added. The other approach
is to construct the name from the context of the definition, that is, from the types it is defined within.
For instance `Lit__InitializeParams_clientInfo` is the "literal" type at the
`clientInfo` field in the `_InitializeParams`
struct. Although this choice is sensitive to the ordering of the components, the code uses this approach,
presuming that reordering components is an unlikely protocol change.)

"tuple" types are generated as Go structs. (There is only one, with two `uint32` fields.)

"and" types are Go structs with embedded type names. (There is only one, `And_Param_workspace_configuration`.)

"or" types are the most complicated. There are a lot of them and there is no simple Go equivalent.
They are defined as structs with a single `Value interface{}` field and custom json marshaling
and unmarshaling code. Users can assign anything to `Value` but the type will be checked, and
correctly marshaled, by the custom marshaling code. The unmarshaling code checks types, so `Value`
will have one of the permitted types. (`nil` is always allowed.) There are about 40 "or" types that
have a single non-null component, and these are converted to the component type.

## Processing

The code parses the json specification file, and scans all the types. It assigns names, as described
above, to the types that are unnamed in the specification, and constructs Go equivalents as required.
(Most of this code is in typenames.go.)

There are four output files. tsclient.go and tsserver.go contain the definition and implementation
of the `protocol.Client` and `protocol.Server` types and the code that dispatches on the Method
of the Request or Notification. tsjson.go contains the custom marshaling and unmarshaling code.
And tsprotocol.go contains the type and const definitions.

### Accommodating gopls

As the code generates output, mostly in generateoutput.go and main.go,
it makes adjustments so that no changes are required to the existing Go code.
(Organizing the computation this way makes the code's structure simpler, but results in
a lot of unused types.)
There are three major classes of these adjustments, and leftover special cases.

The first major
adjustment is to change generated type names to the ones gopls expects. Some of these don't change the
semantics of the type, just the name.
But for historical reasons a lot of them replace "or" types by a single
component of the type. (Until fairly recently Go only saw or used only one of components.)
The `goplsType` map in tables.go controls this process.

The second major adjustment is to the types of fields of structs, which is done using the
`renameProp` map in tables.go.

The third major adjustment handles optionality, controlling `*` and `,omitempty` placement when
the default rules don't match what gopls is expecting. (The map is `goplsStar`, also in tables.go)
(If the intermediate components in expressions of the form `A.B.C.S` were optional, the code would need
a lot of useless checking for nils. Typescript has a language construct to avoid most checks.)

Then there are some additional special cases. There are a few places with adjustments to avoid
recursive types. For instance `LSPArray` is `[]LSPAny`, but `LSPAny` is an "or" type including `LSPArray`.
The solution is to make `LSPAny` an `interface{}`. Another instance is `_InitializeParams.trace`
whose type is an "or" of 3 stringLiterals, which just becomes a `string`.

### Checking

`TestAll(t *testing.T)` checks that there are no unexpected fields in the json specification.

While the code is executing, it checks that all the entries in the maps in tables.go are used.
It also checks that the entries in `renameProp` and `goplsStar` are not redundant.

As a one-time check on the first release of this code, diff-ing the existing and generated tsclient.go
and tsserver.go code results in only whitespace and comment diffs. The existing and generated
tsprotocol.go differ in whitespace and comments, and in a substantial number of new type definitions
that the older, more heuristic, code did not generate. (And the unused type `_InitializeParams` differs
slightly between the new and the old, and is not worth fixing.)

### Some history

The original stub code was written by hand, but with the protocol under active development, that
couldn't last. The web page existed before the json specification, but it lagged the implementation
and was hard to process by machine. So the earlier version of the generating code was written in Typescript, and
used the Typescript compiler's API to parse the protocol code in the repository.
It then used a set of heuristics
to pick out the elements of the protocol, and another set of overlapping heuristics to create the Go code.
The output was functional, but idiosyncratic, and the code was fragile and barely maintainable.

### The future

Most of the adjustments using the maps in tables.go could be removed by making changes, mostly to names,
in the gopls code. Using more "or" types in gopls requires more elaborate, but stereotyped, changes.
But even without all the adjustments, making this its own module would face problems; a number of
dependencies would have to be factored out. And, it is fragile. The custom unmarshaling code knows what
types it expects. A design that return an 'any' on unexpected types would match the json
'ignore unexpected values' philosophy better, but the Go code would need extra checking.


================================================
FILE: gopls/internal/protocol/generate/generate.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"fmt"
	"log"
	"strings"
)

// a newType is a type that needs a name and a definition
// These are the various types that the json specification doesn't name
type newType struct {
	name       string
	properties Properties // for struct/literal types
	items      []*Type    // for other types ("and", "tuple")
	line       int
	kind       string // Or, And, Tuple, Lit, Map
	typ        *Type
}

func generateDoc(out *bytes.Buffer, doc string) {
	if doc == "" {
		return
	}

	if !strings.Contains(doc, "\n") {
		fmt.Fprintf(out, "// %s\n", doc)
		return
	}
	var list bool
	for line := range strings.SplitSeq(doc, "\n") {
		// Lists in metaModel.json start with a dash.
		// To make a go doc list they have to be preceded
		// by a blank line, and indented.
		// (see type TextDccumentFilter in protocol.go)
		if len(line) > 0 && line[0] == '-' {
			if !list {
				list = true
				fmt.Fprintf(out, "//\n")
			}
			fmt.Fprintf(out, "//  %s\n", line)
		} else {
			if len(line) == 0 {
				list = false
			}
			fmt.Fprintf(out, "// %s\n", line)
		}
	}
}

// decide if a property is optional, and if it needs a *
// return ",omitempty" if it is optional, and "*" if it needs a pointer
func propStar(name string, t NameType, gotype string) (omitempty, indirect bool) {
	if t.Optional {
		switch gotype {
		case "uint32", "int32":
			// in FoldingRange.endLine, 0 and empty have different semantics
			// There seem to be no other cases.
		default:
			indirect = true
			omitempty = true
		}
	}
	if strings.HasPrefix(gotype, "[]") || strings.HasPrefix(gotype, "map[") {
		indirect = false // passed by reference, so no need for *
	} else {
		switch gotype {
		case "bool", "string", "interface{}", "any":
			indirect = false // gopls compatibility if t.Optional
		}
	}
	oind, oomit := indirect, omitempty
	if newStar, ok := goplsStar[prop{name, t.Name}]; ok {
		switch newStar {
		case nothing:
			indirect, omitempty = false, false
		case wantOpt:
			indirect, omitempty = false, true
		case wantOptStar:
			indirect, omitempty = true, true
		}
		if indirect == oind && omitempty == oomit { // no change
			log.Printf("goplsStar[ {%q, %q} ](%d) useless %v/%v %v/%v", name, t.Name, t.Line, oind, indirect, oomit, omitempty)
		}
		usedGoplsStar[prop{name, t.Name}] = true
	}

	return
}

func goName(s string) string {
	// Go naming conventions
	if strings.HasSuffix(s, "Id") {
		s = s[:len(s)-len("Id")] + "ID"
	} else if strings.HasSuffix(s, "Uri") {
		s = s[:len(s)-3] + "URI"
	} else if s == "uri" {
		s = "URI"
	} else if s == "id" {
		s = "ID"
	}

	// renames for temporary GOPLS compatibility
	if news := goplsType[s]; news != "" {
		usedGoplsType[s] = true
		s = news
	}
	// Names beginning _ are not exported
	if strings.HasPrefix(s, "_") {
		s = strings.Replace(s, "_", "X", 1)
	}
	if s != "string" { // base types are unchanged (textDocuemnt/diagnostic)
		// Title is deprecated, but a) s is only one word, b) replacement is too heavy-weight
		s = strings.Title(s)
	}
	return s
}


================================================
FILE: gopls/internal/protocol/generate/main.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The generate command generates Go declarations from VSCode's
// description of the Language Server Protocol.
//
// To run it, type 'go generate' in the parent (protocol) directory.
package main

// see https://github.com/golang/go/issues/61217 for discussion of an issue

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/format"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"slices"
	"strings"
)

const vscodeRepo = "https://github.com/microsoft/vscode-languageserver-node"

// lspGitRef names a branch or tag in vscodeRepo.
// It implicitly determines the protocol version of the LSP used by gopls.
// For example, tag release/protocol/3.17.3 of the repo defines
// protocol version 3.17.0 (as declared by the metaData.version field).
// (Point releases are reflected in the git tag version even when they are cosmetic
// and don't change the protocol.)
var lspGitRef = "release/protocol/3.17.6-next.14"

var (
	repodir   = flag.String("d", "", "directory containing clone of "+vscodeRepo)
	outputdir = flag.String("o", ".", "output directory")
	// PJW: not for real code
	lineNumbers = flag.Bool("l", false, "add line numbers to generated output")
)

func main() {
	log.SetFlags(log.Lshortfile) // log file name and line number, not time
	flag.Parse()

	processinline()
}

func processinline() {
	// A local repository may be specified during debugging.
	// The default behavior is to download the canonical version.
	if *repodir == "" {
		tmpdir, err := os.MkdirTemp("", "")
		if err != nil {
			log.Fatal(err)
		}
		defer os.RemoveAll(tmpdir) // ignore error

		// Clone the repository.
		cmd := exec.Command("git", "clone", "--quiet", "--depth=1", "-c", "advice.detachedHead=false", vscodeRepo, "--branch="+lspGitRef, "--single-branch", tmpdir)
		cmd.Stdout = os.Stderr
		cmd.Stderr = os.Stderr
		if err := cmd.Run(); err != nil {
			log.Fatal(err)
		}

		*repodir = tmpdir
	} else {
		lspGitRef = fmt.Sprintf("(not git, local dir %s)", *repodir)
	}

	model := parse(filepath.Join(*repodir, "protocol/metaModel.json"))

	// Although the LSP specification defines RenameParams as extending
	// TextDocumentPositionParams, the metaModel.json definition flattens
	// these properties (likely due to specific comments in the TS definition).
	// See microsoft/vscode-languageserver-node#1698.
	//
	// TODO(hxjiang): delete the patch logic after releasing lsp 3.18.
	for _, s := range model.Structures {
		if s.Name == "RenameParams" {
			s.Properties = slices.DeleteFunc(s.Properties, func(t NameType) bool {
				return t.Name == "position" || t.Name == "textDocument"
			})
			if !slices.ContainsFunc(s.Extends, func(t *Type) bool {
				return t.Kind == "reference" && t.Name == "TextDocumentPositionParams"
			}) {
				s.Extends = append(s.Extends, &Type{
					Kind: "reference",
					Name: "TextDocumentPositionParams",
				})
			}
		}
	}

	// Add a client to server LSP method "command/resolve" for interactive
	// refactoring. The method's param and result are both "ExecuteCommandParams".
	// The types are only accessible from the "workspace/executeCommand" request.
	//
	// See microsoft/language-server-protocol#1164.
	for _, req := range model.Requests {
		if req.Method == "workspace/executeCommand" {
			model.Requests = append(model.Requests, &Request{
				Method:    "command/resolve",
				ErrorData: req.ErrorData,
				Direction: "clientToServer",
				Params:    req.Params,
				Result:    req.Params,
			})
			break
		}
	}

	model.Requests = append(model.Requests, &Request{
		Method:    "interactive/listEnum",
		Direction: "clientToServer",
		Params: &Type{
			Kind: "reference",
			Name: "InteractiveListEnumParams",
		},
		Result: &Type{
			Kind: "array",
			Element: &Type{
				Kind: "reference",
				Name: "FormEnumEntry",
			},
		},
	})

	findTypeNames(model)
	generateOutput(model)

	fileHdr = fileHeader(model)

	// write the files
	writeclient()
	writeserver()
	writeprotocol()
	writejsons()

	checkTables()
}

// common file header for output files
var fileHdr string

func writeclient() {
	out := new(bytes.Buffer)
	fmt.Fprintln(out, fileHdr)
	out.WriteString(
		`import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/internal/jsonrpc2"
)
`)
	out.WriteString("type Client interface {\n")
	for _, k := range cdecls.keys() {
		out.WriteString(cdecls[k])
	}
	out.WriteString("}\n\n")
	out.WriteString(`
func clientDispatch(ctx context.Context, client Client, reply jsonrpc2.Replier, r jsonrpc2.Request) (bool, error) {
	resp, valid, err := ClientDispatchCall(ctx, client, r.Method(), r.Params())
	if !valid {
		return false, nil
	}

	if err != nil {
		return valid, reply(ctx, nil, err)
	} else {
	 	return valid, reply(ctx, resp, nil)
	}
}

func ClientDispatchCall(ctx context.Context, client Client, method string, raw json.RawMessage) (resp any, _ bool, err error) {
	switch method {
`)
	for _, k := range ccases.keys() {
		out.WriteString(ccases[k])
	}
	out.WriteString(("\tdefault:\n\t\treturn nil, false, nil\n\t}\n}\n\n"))
	for _, k := range cfuncs.keys() {
		out.WriteString(cfuncs[k])
	}
	formatTo("tsclient.go", out.Bytes())
}

func writeserver() {
	out := new(bytes.Buffer)
	fmt.Fprintln(out, fileHdr)
	out.WriteString(
		`import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/internal/jsonrpc2"
)
`)
	out.WriteString("type Server interface {\n")
	for _, k := range sdecls.keys() {
		out.WriteString(sdecls[k])
	}
	out.WriteString(`
}
func serverDispatch(ctx context.Context, server Server, reply jsonrpc2.Replier, r jsonrpc2.Request) (bool, error) {
	resp, valid, err := ServerDispatchCall(ctx, server, r.Method(), r.Params())
	if !valid {
		return false, nil
	}

	if err != nil {
		return valid, reply(ctx, nil, err)
	} else {
	 	return valid, reply(ctx, resp, nil)
	}
}

func ServerDispatchCall(ctx context.Context, server Server, method string, raw json.RawMessage) (resp any, _ bool, err error) {
	switch method {
`)
	for _, k := range scases.keys() {
		out.WriteString(scases[k])
	}
	out.WriteString(("\tdefault:\n\t\treturn nil, false, nil\n\t}\n}\n\n"))
	for _, k := range sfuncs.keys() {
		out.WriteString(sfuncs[k])
	}
	formatTo("tsserver.go", out.Bytes())
}

func writeprotocol() {
	out := new(bytes.Buffer)
	fmt.Fprintln(out, fileHdr)
	out.WriteString("import \"encoding/json\"\n\n")

	// The following are unneeded, but make the new code a superset of the old
	hack := func(newer, existing string) {
		if _, ok := types[existing]; !ok {
			log.Fatalf("types[%q] not found", existing)
		}
		types[newer] = strings.Replace(types[existing], existing, newer, 1)
	}
	hack("ConfigurationParams", "ParamConfiguration")
	hack("InitializeParams", "ParamInitialize")
	hack("PreviousResultId", "PreviousResultID")
	hack("WorkspaceFoldersServerCapabilities", "WorkspaceFolders5Gn")
	hack("_InitializeParams", "XInitializeParams")

	for _, k := range types.keys() {
		if k == "WatchKind" {
			types[k] = "type WatchKind = uint32" // strict gopls compatibility needs the '='
		}
		out.WriteString(types[k])
	}

	out.WriteString("\nconst (\n")
	for _, k := range consts.keys() {
		out.WriteString(consts[k])
	}
	out.WriteString(")\n\n")
	formatTo("tsprotocol.go", out.Bytes())
}

func writejsons() {
	out := new(bytes.Buffer)
	fmt.Fprintln(out, fileHdr)
	out.WriteString("import \"encoding/json\"\n\n")
	out.WriteString("import \"fmt\"\n")

	out.WriteString(`
// UnmarshalError indicates that a JSON value did not conform to
// one of the expected cases of an LSP union type.
type UnmarshalError struct {
	msg string
}

func (e UnmarshalError) Error() string {
	return e.msg
}
`)

	for _, k := range jsons.keys() {
		out.WriteString(jsons[k])
	}
	formatTo("tsjson.go", out.Bytes())
}

// formatTo formats the Go source and writes it to *outputdir/basename.
func formatTo(basename string, src []byte) {
	formatted, err := format.Source(src)
	if err != nil {
		failed := filepath.Join("/tmp", basename+".fail")
		if err := os.WriteFile(failed, src, 0644); err != nil {
			log.Fatal(err)
		}
		log.Fatalf("formatting %s: %v (see %s)", basename, err, failed)
	}
	if err := os.WriteFile(filepath.Join(*outputdir, basename), formatted, 0644); err != nil {
		log.Fatal(err)
	}
}

// create the common file header for the output files
func fileHeader(model *Model) string {
	fname := filepath.Join(*repodir, ".git", "HEAD")
	buf, err := os.ReadFile(fname)
	if err != nil {
		log.Fatal(err)
	}
	buf = bytes.TrimSpace(buf)
	var githash string
	if len(buf) == 40 {
		githash = string(buf[:40])
	} else if bytes.HasPrefix(buf, []byte("ref: ")) {
		fname = filepath.Join(*repodir, ".git", string(buf[5:]))
		buf, err = os.ReadFile(fname)
		if err != nil {
			log.Fatal(err)
		}
		githash = string(buf[:40])
	} else {
		log.Fatalf("githash cannot be recovered from %s", fname)
	}

	format := `// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated for LSP. DO NOT EDIT.

package protocol

// Code generated from %[1]s at ref %[2]s (hash %[3]s).
// %[4]s/blob/%[2]s/%[1]s
// LSP metaData.version = %[5]s.

`
	return fmt.Sprintf(format,
		"protocol/metaModel.json", // 1
		lspGitRef,                 // 2
		githash,                   // 3
		vscodeRepo,                // 4
		model.Version.Version)     // 5
}

func parse(fname string) *Model {
	buf, err := os.ReadFile(fname)
	if err != nil {
		log.Fatal(err)
	}
	buf = addLineNumbers(buf)
	model := new(Model)
	if err := json.Unmarshal(buf, model); err != nil {
		log.Fatal(err)
	}
	return model
}

// Type.Value has to be treated specially for literals and maps
func (t *Type) UnmarshalJSON(data []byte) error {
	// First unmarshal only the unambiguous fields.
	var x struct {
		Kind    string  `json:"kind"`
		Items   []*Type `json:"items"`
		Element *Type   `json:"element"`
		Name    string  `json:"name"`
		Key     *Type   `json:"key"`
		Value   any     `json:"value"`
		Line    int     `json:"line"`
	}
	if err := json.Unmarshal(data, &x); err != nil {
		return err
	}
	*t = Type{
		Kind:    x.Kind,
		Items:   x.Items,
		Element: x.Element,
		Name:    x.Name,
		Value:   x.Value,
		Line:    x.Line,
	}

	// Then unmarshal the 'value' field based on the kind.
	// This depends on Unmarshal ignoring fields it doesn't know about.
	switch x.Kind {
	case "map":
		var x struct {
			Key   *Type `json:"key"`
			Value *Type `json:"value"`
		}
		if err := json.Unmarshal(data, &x); err != nil {
			return fmt.Errorf("Type.kind=map: %v", err)
		}
		t.Key = x.Key
		t.Value = x.Value

	case "literal":
		var z struct {
			Value ParseLiteral `json:"value"`
		}

		if err := json.Unmarshal(data, &z); err != nil {
			return fmt.Errorf("Type.kind=literal: %v", err)
		}
		t.Value = z.Value

	case "base", "reference", "array", "and", "or", "tuple",
		"stringLiteral":
		// no-op. never seen integerLiteral or booleanLiteral.

	default:
		return fmt.Errorf("cannot decode Type.kind %q: %s", x.Kind, data)
	}
	return nil
}

// which table entries were not used
func checkTables() {
	for k := range disambiguate {
		if !usedDisambiguate[k] {
			log.Printf("disambiguate[%v] unused", k)
		}
	}
	for k := range renameProp {
		if !usedRenameProp[k] {
			log.Printf("renameProp {%q, %q} unused", k[0], k[1])
		}
	}
	for k := range goplsStar {
		if !usedGoplsStar[k] {
			log.Printf("goplsStar {%q, %q} unused", k[0], k[1])
		}
	}
	for k := range goplsType {
		if !usedGoplsType[k] {
			log.Printf("unused goplsType[%q]->%s", k, goplsType[k])
		}
	}
}


================================================
FILE: gopls/internal/protocol/generate/main_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"testing"
)

// These tests require the result of
//"git clone https://github.com/microsoft/vscode-languageserver-node" in the HOME directory

// this is not a test, but a way to get code coverage,
// (in vscode, just run the test with  "go.coverOnSingleTest": true)
func TestAll(t *testing.T) {
	t.Skip("needs vscode-languageserver-node repository")
	*lineNumbers = true
	log.SetFlags(log.Lshortfile)
	main()
}

// check that the parsed file includes all the information
// from the json file. This test will fail if the spec
// introduces new fields. (one can test this test by
// commenting out the version field in Model.)
func TestParseContents(t *testing.T) {
	t.Skip("needs vscode-languageserver-node repository")
	log.SetFlags(log.Lshortfile)

	// compute our parse of the specification
	dir := os.Getenv("HOME") + "/vscode-languageserver-node"
	fname := dir + "/protocol/metaModel.json"
	v := parse(fname)
	out, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	var our any
	if err := json.Unmarshal(out, &our); err != nil {
		t.Fatal(err)
	}

	// process the json file
	buf, err := os.ReadFile(fname)
	if err != nil {
		t.Fatalf("could not read metaModel.json: %v", err)
	}
	var raw any
	if err := json.Unmarshal(buf, &raw); err != nil {
		t.Fatal(err)
	}

	// convert to strings showing the fields
	them := flatten(raw)
	us := flatten(our)

	// everything in them should be in us
	lesser := make(sortedMap[bool])
	for _, s := range them {
		lesser[s] = true
	}
	greater := make(sortedMap[bool]) // set of fields we have
	for _, s := range us {
		greater[s] = true
	}
	for _, k := range lesser.keys() { // set if fields they have
		if !greater[k] {
			t.Errorf("missing %s", k)
		}
	}
}

// flatten(nil) = "nil"
// flatten(v string) = fmt.Sprintf("%q", v)
// flatten(v float64)= fmt.Sprintf("%g", v)
// flatten(v bool) = fmt.Sprintf("%v", v)
// flatten(v []any) = []string{"[0]"flatten(v[0]), "[1]"flatten(v[1]), ...}
// flatten(v map[string]any) = {"key1": flatten(v["key1"]), "key2": flatten(v["key2"]), ...}
func flatten(x any) []string {
	switch v := x.(type) {
	case nil:
		return []string{"nil"}
	case string:
		return []string{fmt.Sprintf("%q", v)}
	case float64:
		return []string{fmt.Sprintf("%g", v)}
	case bool:
		return []string{fmt.Sprintf("%v", v)}
	case []any:
		var ans []string
		for i, x := range v {
			idx := fmt.Sprintf("[%.3d]", i)
			for _, s := range flatten(x) {
				ans = append(ans, idx+s)
			}
		}
		return ans
	case map[string]any:
		var ans []string
		for k, x := range v {
			idx := fmt.Sprintf("%q:", k)
			for _, s := range flatten(x) {
				ans = append(ans, idx+s)
			}
		}
		return ans
	default:
		log.Fatalf("unexpected type %T", x)
		return nil
	}
}


================================================
FILE: gopls/internal/protocol/generate/output.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"bytes"
	"fmt"
	"log"
	"slices"
	"sort"
	"strings"
)

var (
	// tsclient.go has 3 sections
	cdecls = make(sortedMap[string])
	ccases = make(sortedMap[string])
	cfuncs = make(sortedMap[string])
	// tsserver.go has 3 sections
	sdecls = make(sortedMap[string])
	scases = make(sortedMap[string])
	sfuncs = make(sortedMap[string])
	// tsprotocol.go has 2 sections
	types  = make(sortedMap[string])
	consts = make(sortedMap[string])
	// tsjson has 1 section
	jsons = make(sortedMap[string])
)

func generateOutput(model *Model) {
	for _, r := range model.Requests {
		genDecl(model, r.Method, r.Params, r.Result, r.Direction, r.Line == 0)
		genCase(model, r.Method, r.Params, r.Result, r.Direction)
		genFunc(model, r.Method, r.Params, r.Result, r.Direction, false)
	}
	for _, n := range model.Notifications {
		if n.Method == "$/cancelRequest" {
			continue // handled internally by jsonrpc2
		}
		genDecl(model, n.Method, n.Params, nil, n.Direction, n.Line == 0)
		genCase(model, n.Method, n.Params, nil, n.Direction)
		genFunc(model, n.Method, n.Params, nil, n.Direction, true)
	}
	genStructs(model)
	genAliases(model)
	genGenTypes() // generate the unnamed types
	genConsts(model)
	genMarshal()
}

func genDecl(model *Model, method string, param, result *Type, dir string, experiment bool) {
	fname := methodName(method)
	p := ""
	if notNil(param) {
		p = ", *" + goplsName(param)
	}
	ret := "error"
	if notNil(result) {
		tp := goplsName(result)
		if !hasNilValue(tp) {
			tp = "*" + tp
		}
		ret = fmt.Sprintf("(%s, error)", tp)
	}
	// special gopls compatibility case (PJW: still needed?)
	switch method {
	case "workspace/configuration":
		// was And_Param_workspace_configuration, but the type substitution doesn't work,
		// as ParamConfiguration is embedded in And_Param_workspace_configuration
		p = ", *ParamConfiguration"
		ret = "([]LSPAny, error)"
	}

	var msg string
	{
		var sb strings.Builder

		if doc, ok := prependMethodDocComments[fname]; ok {
			sb.WriteString(doc)
			sb.WriteString("\n\t//\n")
		}

		if experiment {
			sb.WriteString("\t// Note: This is a non-standard protocol extension.\n")
		} else {
			fragment := strings.ReplaceAll(strings.TrimPrefix(method, "$/"), "/", "_")
			fmt.Fprintf(&sb, "\t%s", lspLink(model, fragment))
		}

		fmt.Fprintf(&sb, "\t%s(context.Context%s) %s\n", fname, p, ret)

		msg = sb.String()
	}

	switch dir {
	case "clientToServer":
		sdecls[method] = msg
	case "serverToClient":
		cdecls[method] = msg
	case "both":
		sdecls[method] = msg
		cdecls[method] = msg
	default:
		log.Fatalf("impossible direction %q", dir)
	}
}

func genCase(model *Model, method string, param, result *Type, dir string) {
	extends := func(x, y string) bool {
		for _, struc := range model.Structures {
			if struc.Name == x {
				if contains := slices.ContainsFunc(struc.Extends, func(t *Type) bool {
					return t.Name == y
				}); contains {
					return true
				}
			}
		}
		return false
	}
	out := new(bytes.Buffer)
	fmt.Fprintf(out, "\tcase %q:\n", method)
	var p string
	fname := methodName(method)
	if notNil(param) {
		nm := goplsName(param)
		if method == "workspace/configuration" { // gopls compatibility
			// was And_Param_workspace_configuration, which contains ParamConfiguration
			// so renaming the type leads to circular definitions
			nm = "ParamConfiguration" // gopls compatibility
		}
		fmt.Fprintf(out, "\t\tvar params %s\n", nm)
		out.WriteString("\t\tif err := UnmarshalJSON(raw, &params); err != nil {\n")
		out.WriteString("\t\t\treturn nil, true, fmt.Errorf(\"%%w: %%s\", jsonrpc2.ErrParse, err)\n\t\t}\n")
		p = ", &params"

		// Ensure consistency between Range and Position. If the client provides
		// only a Position, synthesize a zero-width Range at that location.
		//
		// Crucially, we do not clear the Position field. Since this request may
		// be forwarded, the downstream receiver (gopls) will re-validate that
		// the Position lies within the Range.
		//
		// TODO(hxjiang): define util function
		// func (*protocol.Position) EmptyRange() protocol.Range.
		if extends(nm, "TextDocumentPositionParams") {
			out.WriteString(`		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %%v is outside the provided range %%v.", params.Position, params.Range)
		}
`)
		}

	}
	if notNil(result) {
		fmt.Fprintf(out, "\t\tresp, err := %%s.%s(ctx%s)\n", fname, p)
		out.WriteString("\t\tif err != nil {\n")
		out.WriteString("\t\t\treturn nil, true, err\n")
		out.WriteString("\t\t}\n")
		out.WriteString("\t\treturn resp, true, nil\n")
	} else {
		fmt.Fprintf(out, "\t\terr := %%s.%s(ctx%s)\n", fname, p)
		out.WriteString("\t\treturn nil, true, err\n")
	}
	out.WriteString("\n")
	msg := out.String()
	switch dir {
	case "clientToServer":
		scases[method] = fmt.Sprintf(msg, "server")
	case "serverToClient":
		ccases[method] = fmt.Sprintf(msg, "client")
	case "both":
		scases[method] = fmt.Sprintf(msg, "server")
		ccases[method] = fmt.Sprintf(msg, "client")
	default:
		log.Fatalf("impossible direction %q", dir)
	}
}

func genFunc(_ *Model, method string, param, result *Type, dir string, isnotify bool) {
	out := new(bytes.Buffer)
	var p, r string
	var goResult string
	if notNil(param) {
		p = ", params *" + goplsName(param)
	}
	if notNil(result) {
		goResult = goplsName(result)
		if !hasNilValue(goResult) {
			goResult = "*" + goResult
		}
		r = fmt.Sprintf("(%s, error)", goResult)
	} else {
		r = "error"
	}
	// special gopls compatibility case
	switch method {
	case "workspace/configuration":
		// was And_Param_workspace_configuration, but the type substitution doesn't work,
		// as ParamConfiguration is embedded in And_Param_workspace_configuration
		p = ", params *ParamConfiguration"
		r = "([]LSPAny, error)"
		goResult = "[]LSPAny"
	}
	fname := methodName(method)
	fmt.Fprintf(out, "func (s *%%sDispatcher) %s(ctx context.Context%s) %s {\n",
		fname, p, r)

	if !notNil(result) {
		if isnotify {
			if notNil(param) {
				fmt.Fprintf(out, "\treturn s.sender.Notify(ctx, %q, params)\n", method)
			} else {
				fmt.Fprintf(out, "\treturn s.sender.Notify(ctx, %q, nil)\n", method)
			}
		} else {
			if notNil(param) {
				fmt.Fprintf(out, "\treturn s.sender.Call(ctx, %q, params, nil)\n", method)
			} else {
				fmt.Fprintf(out, "\treturn s.sender.Call(ctx, %q, nil, nil)\n", method)
			}
		}
	} else {
		fmt.Fprintf(out, "\tvar result %s\n", goResult)
		if isnotify {
			if notNil(param) {
				fmt.Fprintf(out, "\ts.sender.Notify(ctx, %q, params)\n", method)
			} else {
				fmt.Fprintf(out, "\t\tif err := s.sender.Notify(ctx, %q, nil); err != nil {\n", method)
			}
		} else {
			if notNil(param) {
				fmt.Fprintf(out, "\t\tif err := s.sender.Call(ctx, %q, params, &result); err != nil {\n", method)
			} else {
				fmt.Fprintf(out, "\t\tif err := s.sender.Call(ctx, %q, nil, &result); err != nil {\n", method)
			}
		}
		fmt.Fprintf(out, "\t\treturn nil, err\n\t}\n\treturn result, nil\n")
	}
	out.WriteString("}\n")
	msg := out.String()
	switch dir {
	case "clientToServer":
		sfuncs[method] = fmt.Sprintf(msg, "server")
	case "serverToClient":
		cfuncs[method] = fmt.Sprintf(msg, "client")
	case "both":
		sfuncs[method] = fmt.Sprintf(msg, "server")
		cfuncs[method] = fmt.Sprintf(msg, "client")
	default:
		log.Fatalf("impossible direction %q", dir)
	}
}

func genStructs(model *Model) {
	structures := make(map[string]*Structure) // for expanding Extends
	for _, s := range model.Structures {
		structures[s.Name] = s
	}
	for _, s := range model.Structures {
		out := new(bytes.Buffer)
		generateDoc(out, s.Documentation)
		nm := goName(s.Name)
		if nm == "string" { // an unacceptable strut name
			// a weird case, and needed only so the generated code contains the old gopls code
			nm = "DocumentDiagnosticParams"
		}
		fmt.Fprintf(out, "//\n")
		out.WriteString(lspLink(model, camelCase(s.Name)))
		fmt.Fprintf(out, "type %s struct {%s\n", nm, linex(s.Line))
		// for gopls compatibility, embed most extensions, but expand the rest some day
		props := slices.Clone(s.Properties)
		if s.Name == "SymbolInformation" { // but expand this one
			for _, ex := range s.Extends {
				fmt.Fprintf(out, "\t// extends %s\n", ex.Name)
				props = append(props, structures[ex.Name].Properties...)
			}
			genProps(out, props, nm)
		} else {
			genProps(out, props, nm)
			for _, ex := range s.Extends {
				fmt.Fprintf(out, "\t%s\n", goName(ex.Name))
			}
		}
		for _, ex := range s.Mixins {
			fmt.Fprintf(out, "\t%s\n", goName(ex.Name))
		}
		// TODO(hxjiang): clean this up after microsoft/language-server-protocol#377
		// is fixed and released.
		if nm == "TextDocumentPositionParams" {
			out.WriteString("\t// Range is an optional field representing the user's text selection in the document.\n")
			out.WriteString("\t// If provided, the Position must be contained within this range.\n")
			out.WriteString("\t//\n")
			out.WriteString("\t// Note: This is a non-standard protocol extension. See microsoft/language-server-protocol#377.\n")
			out.WriteString("\tRange Range `json:\"range\"`")
		}
		out.WriteString("}\n")
		types[nm] = out.String()
	}

	// base types
	// (For URI and DocumentURI, see ../uri.go.)
	types["LSPAny"] = "type LSPAny = any\n"
	// A special case, the only previously existing Or type
	types["DocumentDiagnosticReport"] = "type DocumentDiagnosticReport = Or_DocumentDiagnosticReport // (alias) \n"

}

// "FooBar" -> "fooBar"
func camelCase(TitleCased string) string {
	return strings.ToLower(TitleCased[:1]) + TitleCased[1:]
}

func lspLink(model *Model, fragment string) string {
	// Derive URL version from metaData.version in JSON file.
	parts := strings.Split(model.Version.Version, ".") // e.g. "3.17.0"
	return fmt.Sprintf("// See https://microsoft.github.io/language-server-protocol/specifications/lsp/%s.%s/specification#%s\n",
		parts[0], parts[1], // major.minor
		fragment)
}

func genProps(out *bytes.Buffer, props []NameType, name string) {
	for _, p := range props {
		tp := goplsName(p.Type)
		if newNm, ok := renameProp[prop{name, p.Name}]; ok {
			usedRenameProp[prop{name, p.Name}] = true
			if tp == newNm {
				log.Printf("renameProp useless {%q, %q} for %s", name, p.Name, tp)
			}
			tp = newNm
		}
		// it's a pointer if it is optional, or for gopls compatibility
		omit, star := propStar(name, p, tp)
		json := fmt.Sprintf(" `json:\"%s\"`", p.Name)
		if omit {
			json = fmt.Sprintf(" `json:\"%s,omitempty\"`", p.Name)
		}
		generateDoc(out, p.Documentation)
		if docs := appendTypePropDocComments[name]; docs != nil {
			if doc, ok := docs[p.Name]; ok {
				out.WriteString(doc)
			}
		}
		if star {
			fmt.Fprintf(out, "\t%s *%s %s\n", goName(p.Name), tp, json)
		} else {
			fmt.Fprintf(out, "\t%s %s %s\n", goName(p.Name), tp, json)
		}
	}

	if block, ok := appendTypeProp[name]; ok {
		out.WriteString(block)
	}
}

func genAliases(model *Model) {
	for _, ta := range model.TypeAliases {
		out := new(bytes.Buffer)
		generateDoc(out, ta.Documentation)
		nm := goName(ta.Name)
		if nm != ta.Name {
			continue // renamed the type, e.g., "DocumentDiagnosticReport", an or-type to "string"
		}
		tp := goplsName(ta.Type)
		fmt.Fprintf(out, "//\n")
		out.WriteString(lspLink(model, camelCase(ta.Name)))
		fmt.Fprintf(out, "type %s = %s // (alias)\n", nm, tp)
		types[nm] = out.String()
	}
}

func genGenTypes() {
	for _, nt := range genTypes {
		out := new(bytes.Buffer)
		nm := goplsName(nt.typ)
		switch nt.kind {
		case "literal":
			fmt.Fprintf(out, "// created for Literal (%s)\n", nt.name)
			fmt.Fprintf(out, "type %s struct {%s\n", nm, linex(nt.line+1))
			genProps(out, nt.properties, nt.name) // systematic name, not gopls name; is this a good choice?
		case "or":
			if !strings.HasPrefix(nm, "Or") {
				// It was replaced by a narrower type defined elsewhere
				continue
			}
			names := []string{}
			for _, t := range nt.items {
				if notNil(t) {
					names = append(names, goplsName(t))
				}
			}
			sort.Strings(names)
			fmt.Fprintf(out, "// created for Or %v\n", names)
			fmt.Fprintf(out, "type %s struct {%s\n", nm, linex(nt.line+1))
			fmt.Fprintf(out, "\tValue any `json:\"value\"`\n")
		case "and":
			fmt.Fprintf(out, "// created for And\n")
			fmt.Fprintf(out, "type %s struct {%s\n", nm, linex(nt.line+1))
			for _, x := range nt.items {
				nm := goplsName(x)
				fmt.Fprintf(out, "\t%s\n", nm)
			}
		case "tuple": // there's only this one
			nt.name = "UIntCommaUInt"
			fmt.Fprintf(out, "//created for Tuple\ntype %s struct {%s\n", nm, linex(nt.line+1))
			fmt.Fprintf(out, "\tFld0 uint32 `json:\"fld0\"`\n")
			fmt.Fprintf(out, "\tFld1 uint32 `json:\"fld1\"`\n")
		default:
			log.Fatalf("%s not handled", nt.kind)
		}
		out.WriteString("}\n")
		types[nm] = out.String()
	}
}
func genConsts(model *Model) {
	for _, e := range model.Enumerations {
		out := new(bytes.Buffer)
		generateDoc(out, e.Documentation)
		tp := goplsName(e.Type)
		nm := goName(e.Name)
		fmt.Fprintf(out, "type %s %s%s\n", nm, tp, linex(e.Line))
		types[nm] = out.String()
		vals := new(bytes.Buffer)
		generateDoc(vals, e.Documentation)
		for _, v := range e.Values {
			generateDoc(vals, v.Documentation)
			nm := goName(v.Name)
			more, ok := disambiguate[e.Name]
			if ok {
				usedDisambiguate[e.Name] = true
				nm = more.prefix + nm + more.suffix
				nm = goName(nm) // stringType
			}
			var val string
			switch v := v.Value.(type) {
			case string:
				val = fmt.Sprintf("%q", v)
			case float64:
				val = fmt.Sprintf("%d", int(v))
			default:
				log.Fatalf("impossible type %T", v)
			}
			fmt.Fprintf(vals, "\t%s %s = %s%s\n", nm, e.Name, val, linex(v.Line))
		}
		consts[nm] = vals.String()
	}
}
func genMarshal() {
	for _, nt := range genTypes {
		nm := goplsName(nt.typ)
		if !strings.HasPrefix(nm, "Or") {
			continue
		}
		names := []string{}
		for _, t := range nt.items {
			if notNil(t) {
				names = append(names, goplsName(t))
			}
		}
		sort.Strings(names)
		var buf bytes.Buffer
		fmt.Fprintf(&buf, "func (t %s) MarshalJSON() ([]byte, error) {\n", nm)
		buf.WriteString("\tswitch x := t.Value.(type){\n")
		for _, nmx := range names {
			fmt.Fprintf(&buf, "\tcase %s:\n", nmx)
			fmt.Fprintf(&buf, "\t\treturn json.Marshal(x)\n")
		}
		buf.WriteString("\tcase nil:\n\t\treturn []byte(\"null\"), nil\n\t}\n")
		fmt.Fprintf(&buf, "\treturn nil, fmt.Errorf(\"type %%T not one of %v\", t)\n", names)
		buf.WriteString("}\n\n")

		fmt.Fprintf(&buf, "func (t *%s) UnmarshalJSON(x []byte) error {\n", nm)
		buf.WriteString("\tif string(x) == \"null\" {\n\t\tt.Value = nil\n\t\t\treturn nil\n\t}\n")
		for i, nmx := range names {
			fmt.Fprintf(&buf, "\tvar h%d %s\n", i, nmx)
			fmt.Fprintf(&buf, "\tif err := json.Unmarshal(x, &h%d); err == nil {\n\t\tt.Value = h%d\n\t\t\treturn nil\n\t\t}\n", i, i)
		}
		fmt.Fprintf(&buf, "return &UnmarshalError{\"unmarshal failed to match one of %v\"}", names)
		buf.WriteString("}\n\n")
		jsons[nm] = buf.String()
	}
}

func linex(n int) string {
	if *lineNumbers {
		return fmt.Sprintf(" // line %d", n)
	}
	return ""
}

func goplsName(t *Type) string {
	nm := typeNames[t]
	// translate systematic name to gopls name
	if newNm, ok := goplsType[nm]; ok {
		usedGoplsType[nm] = true
		nm = newNm
	}
	return nm
}

func notNil(t *Type) bool { // shutdwon is the special case that needs this
	return t != nil && (t.Kind != "base" || t.Name != "null")
}

func hasNilValue(t string) bool {
	// this may be unreliable, and need a supplementary table
	if strings.HasPrefix(t, "[]") || strings.HasPrefix(t, "*") {
		return true
	}
	if t == "interface{}" || t == "any" {
		return true
	}
	// that's all the cases that occur currently
	return false
}


================================================
FILE: gopls/internal/protocol/generate/tables.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import "log"

// prop combines the name of a property (class.field) with the name of
// the structure it is in, using LSP field capitalization.
type prop [2]string

const (
	nothing     = iota
	wantOpt     // omitempty
	wantOptStar // omitempty, indirect
)

// goplsStar records the optionality of each field in the protocol.
// The comments are vague hints as to why removing the line is not trivial.
// A.B.C.D means that one of B or C would change to a pointer
// so a test or initialization would be needed
var goplsStar = map[prop]int{
	{"AnnotatedTextEdit", "annotationId"}:  wantOptStar,
	{"ClientCapabilities", "textDocument"}: wantOpt, // A.B.C.D at fake/editor.go:255
	{"ClientCapabilities", "window"}:       wantOpt, // test failures
	{"ClientCapabilities", "workspace"}:    wantOpt, // test failures
	{"CodeAction", "kind"}:                 wantOpt, // A.B.C.D

	{"CodeActionClientCapabilities", "codeActionLiteralSupport"}: wantOpt, // test failures

	{"CompletionClientCapabilities", "completionItem"}: wantOpt, // A.B.C.D
	{"CompletionClientCapabilities", "insertTextMode"}: wantOpt, // A.B.C.D
	{"CompletionItem", "kind"}:                         wantOpt, // need temporary variables
	{"CompletionParams", "context"}:                    wantOpt, // needs nil checks

	{"Diagnostic", "severity"}:            wantOpt,     // needs nil checks or more careful thought
	{"DidSaveTextDocumentParams", "text"}: wantOptStar, // capabilities_test.go:112 logic
	{"DocumentHighlight", "kind"}:         wantOpt,     // need temporary variables

	{"FoldingRange", "startLine"}:      wantOptStar, // unset != zero (#71489)
	{"FoldingRange", "startCharacter"}: wantOptStar, // unset != zero (#71489)
	{"FoldingRange", "endLine"}:        wantOptStar, // unset != zero (#71489)
	{"FoldingRange", "endCharacter"}:   wantOptStar, // unset != zero (#71489)

	{"Hover", "range"}:    wantOpt, // complex expressions
	{"InlayHint", "kind"}: wantOpt, // temporary variables

	{"PublishDiagnosticsParams", "version"}:                   wantOpt,     // zero => missing (#73501)
	{"SignatureHelp", "activeParameter"}:                      wantOptStar, // unset != zero
	{"SignatureInformation", "activeParameter"}:               wantOptStar, // unset != zero
	{"TextDocumentClientCapabilities", "codeAction"}:          wantOpt,     // A.B.C.D
	{"TextDocumentClientCapabilities", "completion"}:          wantOpt,     // A.B.C.D
	{"TextDocumentClientCapabilities", "documentSymbol"}:      wantOpt,     // A.B.C.D
	{"TextDocumentClientCapabilities", "publishDiagnostics"}:  wantOpt,     // A.B.C.D
	{"TextDocumentClientCapabilities", "semanticTokens"}:      wantOpt,     // A.B.C.D
	{"TextDocumentContentChangePartial", "range"}:             wantOptStar, // == nil test
	{"TextDocumentContentChangePartial", "rangeLength"}:       wantOptStar, // unset != zero
	{"TextDocumentSyncOptions", "change"}:                     wantOpt,     // &constant
	{"WorkDoneProgressBegin", "percentage"}:                   wantOptStar, // unset != zero
	{"WorkDoneProgressParams", "workDoneToken"}:               wantOpt,     // test failures
	{"WorkDoneProgressReport", "percentage"}:                  wantOptStar, // unset != zero
	{"WorkspaceClientCapabilities", "didChangeConfiguration"}: wantOpt,     // A.B.C.D
	{"WorkspaceClientCapabilities", "didChangeWatchedFiles"}:  wantOpt,     // A.B.C.D
}

// keep track of which entries in goplsStar are used
var usedGoplsStar = make(map[prop]bool)

// For gopls compatibility, use a different, typically more restrictive, type for some fields.
var renameProp = map[prop]string{
	{"CancelParams", "id"}:   "any",
	{"Command", "arguments"}: "[]json.RawMessage",
	{"CodeAction", "data"}:   "json.RawMessage", // delay unmarshalling commands
	{"Diagnostic", "code"}:   "any",
	{"Diagnostic", "data"}:   "json.RawMessage", // delay unmarshalling quickfixes

	{"DocumentDiagnosticReportPartialResult", "relatedDocuments"}: "map[DocumentURI]any",

	{"ExecuteCommandParams", "arguments"}: "[]json.RawMessage",
	{"FoldingRange", "kind"}:              "string",
	{"Hover", "contents"}:                 "MarkupContent",
	{"InlayHint", "label"}:                "[]InlayHintLabelPart",

	{"RelatedFullDocumentDiagnosticReport", "relatedDocuments"}:      "map[DocumentURI]any",
	{"RelatedUnchangedDocumentDiagnosticReport", "relatedDocuments"}: "map[DocumentURI]any",

	// PJW: this one is tricky.
	{"ServerCapabilities", "codeActionProvider"}: "any",

	{"ServerCapabilities", "inlayHintProvider"}: "any",
	// slightly tricky
	{"ServerCapabilities", "renameProvider"}: "any",
	// slightly tricky
	{"ServerCapabilities", "semanticTokensProvider"}: "any",
	// slightly tricky
	{"ServerCapabilities", "textDocumentSync"}: "any",
	{"TextDocumentSyncOptions", "save"}:        "SaveOptions",
	{"WorkspaceEdit", "documentChanges"}:       "[]DocumentChange",
}

// which entries of renameProp were used
var usedRenameProp = make(map[prop]bool)

type adjust struct {
	prefix, suffix string
}

// disambiguate specifies prefixes or suffixes to add to all values of
// some enum types to avoid name conflicts
var disambiguate = map[string]adjust{
	"CodeActionTriggerKind":        {"CodeAction", ""},
	"CompletionItemKind":           {"", "Completion"},
	"CompletionItemTag":            {"Compl", ""},
	"DiagnosticSeverity":           {"Severity", ""},
	"DocumentDiagnosticReportKind": {"Diagnostic", ""},
	"FileOperationPatternKind":     {"", "Pattern"},
	"InlineCompletionTriggerKind":  {"Inline", ""},
	"InsertTextFormat":             {"", "TextFormat"},
	"LanguageKind":                 {"Lang", ""},
	"SemanticTokenModifiers":       {"Mod", ""},
	"SemanticTokenTypes":           {"", "Type"},
	"SignatureHelpTriggerKind":     {"Sig", ""},
	"SymbolTag":                    {"", "Symbol"},
	"WatchKind":                    {"Watch", ""},
}

// which entries of disambiguate got used
var usedDisambiguate = make(map[string]bool)

// for gopls compatibility, replace generated type names with existing ones
var goplsType = map[string]string{
	"And_RegOpt_textDocument_colorPresentation": "WorkDoneProgressOptionsAndTextDocumentRegistrationOptions",
	"ConfigurationParams":                       "ParamConfiguration",
	"DocumentUri":                               "DocumentURI",
	"InitializeParams":                          "ParamInitialize",
	"LSPAny":                                    "any",

	"Lit_SemanticTokensOptions_range_Item1": "PRangeESemanticTokensOptions",

	"Or_Declaration": "[]Location",
	"Or_DidChangeConfigurationRegistrationOptions_section": "OrPSection_workspace_didChangeConfiguration",
	"Or_InlayHintLabelPart_tooltip":                        "OrPTooltipPLabel",
	"Or_InlayHint_tooltip":                                 "OrPTooltip_textDocument_inlayHint",
	"Or_LSPAny":                                            "any",

	"Or_ParameterInformation_documentation":            "string",
	"Or_ParameterInformation_label":                    "string",
	"Or_PrepareRenameResult":                           "PrepareRenamePlaceholder",
	"Or_ProgressToken":                                 "any",
	"Or_Result_textDocument_completion":                "CompletionList",
	"Or_Result_textDocument_declaration":               "Or_textDocument_declaration",
	"Or_Result_textDocument_definition":                "[]Location",
	"Or_Result_textDocument_documentSymbol":            "[]any",
	"Or_Result_textDocument_implementation":            "[]Location",
	"Or_Result_textDocument_semanticTokens_full_delta": "any",
	"Or_Result_textDocument_typeDefinition":            "[]Location",
	"Or_Result_workspace_symbol":                       "[]SymbolInformation",
	"Or_TextDocumentContentChangeEvent":                "TextDocumentContentChangePartial",
	"Or_RelativePattern_baseUri":                       "DocumentURI",

	"Or_WorkspaceFoldersServerCapabilities_changeNotifications": "string",
	"Or_WorkspaceSymbol_location":                               "OrPLocation_workspace_symbol",

	"Tuple_ParameterInformation_label_Item1": "UIntCommaUInt",
	"WorkspaceFoldersServerCapabilities":     "WorkspaceFolders5Gn",
	"[]LSPAny":                               "[]any",

	"[]Or_Result_textDocument_codeAction_Item0_Elem": "[]CodeAction",
	"[]PreviousResultId":                             "[]PreviousResultID",
	"[]uinteger":                                     "[]uint32",
	"boolean":                                        "bool",
	"decimal":                                        "float64",
	"integer":                                        "int32",
	"map[DocumentUri][]TextEdit":                     "map[DocumentURI][]TextEdit",
	"uinteger":                                       "uint32",
}

var usedGoplsType = make(map[string]bool)

// methodNames is a map from the method to the name of the function that handles it
var methodNames = map[string]string{
	"$/cancelRequest":                        "CancelRequest",
	"$/logTrace":                             "LogTrace",
	"$/progress":                             "Progress",
	"$/setTrace":                             "SetTrace",
	"callHierarchy/incomingCalls":            "IncomingCalls",
	"callHierarchy/outgoingCalls":            "OutgoingCalls",
	"client/registerCapability":              "RegisterCapability",
	"client/unregisterCapability":            "UnregisterCapability",
	"codeAction/resolve":                     "ResolveCodeAction",
	"codeLens/resolve":                       "ResolveCodeLens",
	"completionItem/resolve":                 "ResolveCompletionItem",
	"command/resolve":                        "ResolveCommand",
	"documentLink/resolve":                   "ResolveDocumentLink",
	"exit":                                   "Exit",
	"initialize":                             "Initialize",
	"initialized":                            "Initialized",
	"inlayHint/resolve":                      "Resolve",
	"interactive/listEnum":                   "InteractiveListEnum",
	"notebookDocument/didChange":             "DidChangeNotebookDocument",
	"notebookDocument/didClose":              "DidCloseNotebookDocument",
	"notebookDocument/didOpen":               "DidOpenNotebookDocument",
	"notebookDocument/didSave":               "DidSaveNotebookDocument",
	"shutdown":                               "Shutdown",
	"telemetry/event":                        "Event",
	"textDocument/codeAction":                "CodeAction",
	"textDocument/codeLens":                  "CodeLens",
	"textDocument/colorPresentation":         "ColorPresentation",
	"textDocument/completion":                "Completion",
	"textDocument/declaration":               "Declaration",
	"textDocument/definition":                "Definition",
	"textDocument/diagnostic":                "Diagnostic",
	"textDocument/didChange":                 "DidChange",
	"textDocument/didClose":                  "DidClose",
	"textDocument/didOpen":                   "DidOpen",
	"textDocument/didSave":                   "DidSave",
	"textDocument/documentColor":             "DocumentColor",
	"textDocument/documentHighlight":         "DocumentHighlight",
	"textDocument/documentLink":              "DocumentLink",
	"textDocument/documentSymbol":            "DocumentSymbol",
	"textDocument/foldingRange":              "FoldingRange",
	"textDocument/formatting":                "Formatting",
	"textDocument/hover":                     "Hover",
	"textDocument/implementation":            "Implementation",
	"textDocument/inlayHint":                 "InlayHint",
	"textDocument/inlineCompletion":          "InlineCompletion",
	"textDocument/inlineValue":               "InlineValue",
	"textDocument/linkedEditingRange":        "LinkedEditingRange",
	"textDocument/moniker":                   "Moniker",
	"textDocument/onTypeFormatting":          "OnTypeFormatting",
	"textDocument/prepareCallHierarchy":      "PrepareCallHierarchy",
	"textDocument/prepareRename":             "PrepareRename",
	"textDocument/prepareTypeHierarchy":      "PrepareTypeHierarchy",
	"textDocument/publishDiagnostics":        "PublishDiagnostics",
	"textDocument/rangeFormatting":           "RangeFormatting",
	"textDocument/rangesFormatting":          "RangesFormatting",
	"textDocument/references":                "References",
	"textDocument/rename":                    "Rename",
	"textDocument/selectionRange":            "SelectionRange",
	"textDocument/semanticTokens/full":       "SemanticTokensFull",
	"textDocument/semanticTokens/full/delta": "SemanticTokensFullDelta",
	"textDocument/semanticTokens/range":      "SemanticTokensRange",
	"textDocument/signatureHelp":             "SignatureHelp",
	"textDocument/typeDefinition":            "TypeDefinition",
	"textDocument/willSave":                  "WillSave",
	"textDocument/willSaveWaitUntil":         "WillSaveWaitUntil",
	"typeHierarchy/subtypes":                 "Subtypes",
	"typeHierarchy/supertypes":               "Supertypes",
	"window/logMessage":                      "LogMessage",
	"window/showDocument":                    "ShowDocument",
	"window/showMessage":                     "ShowMessage",
	"window/showMessageRequest":              "ShowMessageRequest",
	"window/workDoneProgress/cancel":         "WorkDoneProgressCancel",
	"window/workDoneProgress/create":         "WorkDoneProgressCreate",
	"workspace/applyEdit":                    "ApplyEdit",
	"workspace/codeLens/refresh":             "CodeLensRefresh",
	"workspace/configuration":                "Configuration",
	"workspace/diagnostic":                   "DiagnosticWorkspace",
	"workspace/diagnostic/refresh":           "DiagnosticRefresh",
	"workspace/didChangeConfiguration":       "DidChangeConfiguration",
	"workspace/didChangeWatchedFiles":        "DidChangeWatchedFiles",
	"workspace/didChangeWorkspaceFolders":    "DidChangeWorkspaceFolders",
	"workspace/didCreateFiles":               "DidCreateFiles",
	"workspace/didDeleteFiles":               "DidDeleteFiles",
	"workspace/didRenameFiles":               "DidRenameFiles",
	"workspace/executeCommand":               "ExecuteCommand",
	"workspace/foldingRange/refresh":         "FoldingRangeRefresh",
	"workspace/inlayHint/refresh":            "InlayHintRefresh",
	"workspace/inlineValue/refresh":          "InlineValueRefresh",
	"workspace/semanticTokens/refresh":       "SemanticTokensRefresh",
	"workspace/symbol":                       "Symbol",
	"workspace/textDocumentContent":          "TextDocumentContent",
	"workspace/textDocumentContent/refresh":  "TextDocumentContentRefresh",
	"workspace/willCreateFiles":              "WillCreateFiles",
	"workspace/willDeleteFiles":              "WillDeleteFiles",
	"workspace/willRenameFiles":              "WillRenameFiles",
	"workspace/workspaceFolders":             "WorkspaceFolders",
	"workspaceSymbol/resolve":                "ResolveWorkspaceSymbol",
}

func methodName(method string) string {
	ans := methodNames[method]
	if ans == "" {
		log.Fatalf("unknown method %q", method)
	}
	return ans
}

// prependMethodDocComments specifies doc comments that will be prepend to
// an LSP method name defined in both Server and Client interface.
var prependMethodDocComments = map[string]string{
	"ResolveCommand": `// To support microsoft/language-server-protocol#1164, the language server
	// need to read the form with client-supplied answers and either returns an
	// ExecuteCommandParams with errors in the form surfacing the error to the
	// client, or an ExecuteCommandParams with interactive properties empty (e.g
	// formFields, formAnswers) and user information integrated in original
	// properties.
	//
	// The language client may call "command/resolve" if the language server
	// returns an ExecuteCommandParams with errors or try asking the user for
	// completing the form again.
	// The language client may call "command/resolve" multiple times with user
	// filled (re-filled) answers in the form until it obtains an
	// ExecuteCommandParams with interactive properties empty (e.g. formFields,
	// formAnswers). by then the original properties contains all information,
	// the client can call "workspace/executeCommand" with the same param.
	//
	// Standard resolution (e.g., "codeAction/resolve") cannot be used here because
	// it is often triggered eagerly (e.g., for previews), prohibiting interactive
	// forms. "command/resolve" is introduced to handle the interactive flow
	// strictly *after* the user has explicitly indicated intention (e.g., by
	// clicking), making it safe for Code Actions and other refactorings.`,
	"InteractiveListEnum": `// InteractiveListEnum is the request handler for fetching dynamic enum options.
	//
	// This method is called by the client when the user interacts with a
	// FormFieldTypeLazyEnum field (e.g., typing in a combo box). The server
	// uses the provided Action and Params to determine the context (e.g.,
	// "search workspace symbols for interfaces") and returns a filtered list
	// of matching entries.`,
}

// prependMethodDocComments specifies doc comments that will be prepend to
// an LSP type's properties existing doc comments.
var appendTypePropDocComments = map[string]map[string]string{
	"TextDocumentPositionParams": {"position": `	//
	// Deprecated: gopls should use [TextDocumentPositionParams.Range] instead.
`},
}

// appendTypeProp specifies block of code (typically properties with doc comment)
// that will be append to a struct.
var appendTypeProp = map[string]string{
	"ExecuteCommandParams": `
	// Support interactive command execution.
	//
	// Note: This is a non-standard protocol extension. See golang/go#76331.
	InteractiveParams
`,
}


================================================
FILE: gopls/internal/protocol/generate/typenames.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"log"
	"strings"
)

var typeNames = make(map[*Type]string)
var genTypes []*newType

func findTypeNames(model *Model) {
	for _, s := range model.Structures {
		for _, e := range s.Extends {
			nameType(e, nil) // all references
		}
		for _, m := range s.Mixins {
			nameType(m, nil) // all references
		}
		for _, p := range s.Properties {
			nameType(p.Type, []string{s.Name, p.Name})
		}
	}
	for _, t := range model.Enumerations {
		nameType(t.Type, []string{t.Name})
	}
	for _, t := range model.TypeAliases {
		nameType(t.Type, []string{t.Name})
	}
	for _, r := range model.Requests {
		nameType(r.Params, []string{"Param", r.Method})
		nameType(r.Result, []string{"Result", r.Method})
		nameType(r.RegistrationOptions, []string{"RegOpt", r.Method})
	}
	for _, n := range model.Notifications {
		nameType(n.Params, []string{"Param", n.Method})
		nameType(n.RegistrationOptions, []string{"RegOpt", n.Method})
	}
}

// nameType populates typeNames[t] with the computed name of the type.
// path is the list of enclosing constructs in the JSON model.
func nameType(t *Type, path []string) string {
	if t == nil || typeNames[t] != "" {
		return ""
	}
	switch t.Kind {
	case "base":
		typeNames[t] = t.Name
		return t.Name
	case "reference":
		typeNames[t] = t.Name
		return t.Name
	case "array":
		nm := "[]" + nameType(t.Element, append(path, "Elem"))
		typeNames[t] = nm
		return nm
	case "map":
		key := nameType(t.Key, nil) // never a generated type
		value := nameType(t.Value.(*Type), append(path, "Value"))
		nm := "map[" + key + "]" + value
		typeNames[t] = nm
		return nm
	// generated types
	case "and":
		nm := nameFromPath("And", path)
		typeNames[t] = nm
		for _, it := range t.Items {
			nameType(it, append(path, "Item"))
		}
		genTypes = append(genTypes, &newType{
			name:  nm,
			typ:   t,
			kind:  "and",
			items: t.Items,
			line:  t.Line,
		})
		return nm
	case "literal":
		nm := nameFromPath("Lit", path)
		typeNames[t] = nm
		for _, p := range t.Value.(ParseLiteral).Properties {
			nameType(p.Type, append(path, p.Name))
		}
		genTypes = append(genTypes, &newType{
			name:       nm,
			typ:        t,
			kind:       "literal",
			properties: t.Value.(ParseLiteral).Properties,
			line:       t.Line,
		})
		return nm
	case "tuple":
		nm := nameFromPath("Tuple", path)
		typeNames[t] = nm
		for _, it := range t.Items {
			nameType(it, append(path, "Item"))
		}
		genTypes = append(genTypes, &newType{
			name:  nm,
			typ:   t,
			kind:  "tuple",
			items: t.Items,
			line:  t.Line,
		})
		return nm
	case "or":
		nm := nameFromPath("Or", path)
		typeNames[t] = nm
		for i, it := range t.Items {
			// these names depend on the ordering within the "or" type
			nameType(it, append(path, fmt.Sprintf("Item%d", i)))
		}
		// this code handles an "or" of stringLiterals (_InitializeParams.trace)
		names := make(map[string]int)
		var msg strings.Builder
		for _, it := range t.Items {
			if line, ok := names[typeNames[it]]; ok {
				// duplicate component names are bad
				fmt.Fprintf(&msg, "lines %d %d dup, %s for %s\n", line, it.Line, typeNames[it], nm)
			}
			names[typeNames[it]] = t.Line
		}
		// this code handles an "or" of stringLiterals (_InitializeParams.trace)
		if len(names) == 1 {
			var solekey string
			for k := range names {
				solekey = k // the sole name
			}
			if solekey == "string" { // _InitializeParams.trace
				typeNames[t] = "string"
				return "string"
			}
			// otherwise unexpected
			log.Printf("unexpected: single-case 'or' type has non-string key %s: %s", nm, solekey)
			log.Fatal(msg.String())
		} else if len(names) == 2 {
			// if one of the names is null, just use the other, rather than generating an "or".
			// This removes about 40 types from the generated code. An entry in goplsStar
			// could be added to handle the null case, if necessary.
			newNm := ""
			sawNull := false
			for k := range names {
				if k == "null" {
					sawNull = true
				} else {
					newNm = k
				}
			}
			if sawNull {
				typeNames[t] = newNm
				return newNm
			}
		}
		genTypes = append(genTypes, &newType{
			name:  nm,
			typ:   t,
			kind:  "or",
			items: t.Items,
			line:  t.Line,
		})
		return nm
	case "stringLiteral": // a single type, like 'kind' or 'rename'
		typeNames[t] = "string"
		return "string"
	default:
		log.Fatalf("nameType: %T unexpected, line:%d path:%v", t, t.Line, path)
		panic("unreachable in nameType")
	}
}

func nameFromPath(prefix string, path []string) string {
	nm := prefix + "_" + strings.Join(path, "_")
	// methods have slashes
	nm = strings.ReplaceAll(nm, "/", "_")
	return nm
}


================================================
FILE: gopls/internal/protocol/generate/types.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"fmt"
	"sort"
)

// Model contains the parsed version of the spec
type Model struct {
	Version       Metadata        `json:"metaData"`
	Requests      []*Request      `json:"requests"`
	Notifications []*Notification `json:"notifications"`
	Structures    []*Structure    `json:"structures"`
	Enumerations  []*Enumeration  `json:"enumerations"`
	TypeAliases   []*TypeAlias    `json:"typeAliases"`
	Line          int             `json:"line"`
}

// Metadata is information about the version of the spec
type Metadata struct {
	Version string `json:"version"`
	Line    int    `json:"line"`
}

// A Request is the parsed version of an LSP request
type Request struct {
	Documentation       string `json:"documentation"`
	ErrorData           *Type  `json:"errorData"`
	Direction           string `json:"messageDirection"`
	Method              string `json:"method"`
	Params              *Type  `json:"params"`
	PartialResult       *Type  `json:"partialResult"`
	Proposed            bool   `json:"proposed"`
	RegistrationMethod  string `json:"registrationMethod"`
	RegistrationOptions *Type  `json:"registrationOptions"`
	Result              *Type  `json:"result"`
	Since               string `json:"since"`
	Line                int    `json:"line"`
}

// A Notification is the parsed version of an LSP notification
type Notification struct {
	Documentation       string `json:"documentation"`
	Direction           string `json:"messageDirection"`
	Method              string `json:"method"`
	Params              *Type  `json:"params"`
	Proposed            bool   `json:"proposed"`
	RegistrationMethod  string `json:"registrationMethod"`
	RegistrationOptions *Type  `json:"registrationOptions"`
	Since               string `json:"since"`
	Line                int    `json:"line"`
}

// A Structure is the parsed version of an LSP structure from the spec
type Structure struct {
	Documentation string     `json:"documentation"`
	Extends       []*Type    `json:"extends"`
	Mixins        []*Type    `json:"mixins"`
	Name          string     `json:"name"`
	Properties    []NameType `json:"properties"`
	Proposed      bool       `json:"proposed"`
	Since         string     `json:"since"`
	Line          int        `json:"line"`
}

// An enumeration is the parsed version of an LSP enumeration from the spec
type Enumeration struct {
	Documentation        string      `json:"documentation"`
	Name                 string      `json:"name"`
	Proposed             bool        `json:"proposed"`
	Since                string      `json:"since"`
	SupportsCustomValues bool        `json:"supportsCustomValues"`
	Type                 *Type       `json:"type"`
	Values               []NameValue `json:"values"`
	Line                 int         `json:"line"`
}

// A TypeAlias is the parsed version of an LSP type alias from the spec
type TypeAlias struct {
	Documentation string `json:"documentation"`
	Deprecated    string `json:"deprecated"`
	Name          string `json:"name"`
	Proposed      bool   `json:"proposed"`
	Since         string `json:"since"`
	Type          *Type  `json:"type"`
	Line          int    `json:"line"`
}

// A NameValue describes an enumeration constant
type NameValue struct {
	Documentation string `json:"documentation"`
	Name          string `json:"name"`
	Proposed      bool   `json:"proposed"`
	Since         string `json:"since"`
	Value         any    `json:"value"` // number or string
	Line          int    `json:"line"`
}

// A Type is the parsed version of an LSP type from the spec,
// or a Type the code constructs
type Type struct {
	Kind    string  `json:"kind"`    // -- which kind goes with which field --
	Items   []*Type `json:"items"`   // "and", "or", "tuple"
	Element *Type   `json:"element"` // "array"
	Name    string  `json:"name"`    // "base", "reference"
	Key     *Type   `json:"key"`     // "map"
	Value   any     `json:"value"`   // "map", "stringLiteral", "literal"
	Line    int     `json:"line"`    // JSON source line
}

// ParseLiteral is Type.Value when Type.Kind is "literal"
type ParseLiteral struct {
	Properties `json:"properties"`
}

// A NameType represents the name and type of a structure element
type NameType struct {
	Name          string `json:"name"`
	Type          *Type  `json:"type"`
	Optional      bool   `json:"optional"`
	Documentation string `json:"documentation"`
	Deprecated    string `json:"deprecated"`
	Since         string `json:"since"`
	Proposed      bool   `json:"proposed"`
	Line          int    `json:"line"`
}

// Properties are the collection of structure fields
type Properties []NameType

// addLineNumbers adds a "line" field to each object in the JSON.
func addLineNumbers(buf []byte) []byte {
	var ans []byte
	// In the specification .json file, the delimiter '{' is
	// always followed by a newline. There are other {s embedded in strings.
	// json.Token does not return \n, or :, or , so using it would
	// require parsing the json to reconstruct the missing information.
	for linecnt, i := 1, 0; i < len(buf); i++ {
		ans = append(ans, buf[i])
		switch buf[i] {
		case '{':
			if buf[i+1] == '\n' {
				ans = append(ans, fmt.Sprintf(`"line": %d, `, linecnt)...)
				// warning: this would fail if the spec file had
				// `"value": {\n}`, but it does not, as comma is a separator.
			}
		case '\n':
			linecnt++
		}
	}
	return ans
}

type sortedMap[T any] map[string]T

func (s sortedMap[T]) keys() []string {
	var keys []string
	for k := range s {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}


================================================
FILE: gopls/internal/protocol/json_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol_test

import (
	"encoding/json"
	"fmt"
	"regexp"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
)

// verify that type errors in Initialize lsp messages don't cause
// any other unmarshalling errors. The code looks at single values and the
// first component of array values. Each occurrence is replaced by something
// of a different type,  the resulting string unmarshalled, and compared to
// the unmarshalling of the unchanged strings. The test passes if there is no
// more than a single difference reported. That is, if changing a single value
// in the message changes no more than a single value in the unmarshalled struct,
// it is safe to ignore *json.UnmarshalTypeError.

// strings are changed to numbers or bools (true)
// bools are changed to numbers or strings
// numbers are changed to strings or bools

// a recent Initialize message taken from a log (at some point
// some field incompatibly changed from bool to int32)
const input = `{"processId":46408,"clientInfo":{"name":"Visual Studio Code - Insiders","version":"1.76.0-insider"},"locale":"en-us","rootPath":"/Users/pjw/hakim","rootUri":"file:///Users/pjw/hakim","capabilities":{"workspace":{"applyEdit":true,"workspaceEdit":{"documentChanges":true,"resourceOperations":["create","rename","delete"],"failureHandling":"textOnlyTransactional","normalizesLineEndings":true,"changeAnnotationSupport":{"groupsOnLabel":true}},"configuration":true,"didChangeWatchedFiles":{"dynamicRegistration":true,"relativePatternSupport":true},"symbol":{"dynamicRegistration":true,"symbolKind":{"valueSet":[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]},"tagSupport":{"valueSet":[1]},"resolveSupport":{"properties":["location.range"]}},"codeLens":{"refreshSupport":true},"executeCommand":{"dynamicRegistration":true},"didChangeConfiguration":{"dynamicRegistration":true},"workspaceFolders":true,"semanticTokens":{"refreshSupport":true},"fileOperations":{"dynamicRegistration":true,"didCreate":true,"didRename":true,"didDelete":true,"willCreate":true,"willRename":true,"willDelete":true},"inlineValue":{"refreshSupport":true},"inlayHint":{"refreshSupport":true},"diagnostics":{"refreshSupport":true}},"textDocument":{"publishDiagnostics":{"relatedInformation":true,"versionSupport":false,"tagSupport":{"valueSet":[1,2]},"codeDescriptionSupport":true,"dataSupport":true},"synchronization":{"dynamicRegistration":true,"willSave":true,"willSaveWaitUntil":true,"didSave":true},"completion":{"dynamicRegistration":true,"contextSupport":true,"completionItem":{"snippetSupport":true,"commitCharactersSupport":true,"documentationFormat":["markdown","plaintext"],"deprecatedSupport":true,"preselectSupport":true,"tagSupport":{"valueSet":[1]},"insertReplaceSupport":true,"resolveSupport":{"properties":["documentation","detail","additionalTextEdits"]},"insertTextModeSupport":{"valueSet":[1,2]},"labelDetailsSupport":true},"insertTextMode":2,"completionItemKind":{"valueSet":[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25]},"completionList":{"itemDefaults":["commitCharacters","editRange","insertTextFormat","insertTextMode"]}},"hover":{"dynamicRegistration":true,"contentFormat":["markdown","plaintext"]},"signatureHelp":{"dynamicRegistration":true,"signatureInformation":{"documentationFormat":["markdown","plaintext"],"parameterInformation":{"labelOffsetSupport":true},"activeParameterSupport":true},"contextSupport":true},"definition":{"dynamicRegistration":true,"linkSupport":true},"references":{"dynamicRegistration":true},"documentHighlight":{"dynamicRegistration":true},"documentSymbol":{"dynamicRegistration":true,"symbolKind":{"valueSet":[1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26]},"hierarchicalDocumentSymbolSupport":true,"tagSupport":{"valueSet":[1]},"labelSupport":true},"codeAction":{"dynamicRegistration":true,"isPreferredSupport":true,"disabledSupport":true,"dataSupport":true,"resolveSupport":{"properties":["edit"]},"codeActionLiteralSupport":{"codeActionKind":{"valueSet":["","quickfix","refactor","refactor.extract","refactor.inline","refactor.rewrite","source","source.organizeImports"]}},"honorsChangeAnnotations":false},"codeLens":{"dynamicRegistration":true},"formatting":{"dynamicRegistration":true},"rangeFormatting":{"dynamicRegistration":true},"onTypeFormatting":{"dynamicRegistration":true},"rename":{"dynamicRegistration":true,"prepareSupport":true,"prepareSupportDefaultBehavior":1,"honorsChangeAnnotations":true},"documentLink":{"dynamicRegistration":true,"tooltipSupport":true},"typeDefinition":{"dynamicRegistration":true,"linkSupport":true},"implementation":{"dynamicRegistration":true,"linkSupport":true},"colorProvider":{"dynamicRegistration":true},"foldingRange":{"dynamicRegistration":true,"rangeLimit":5000,"lineFoldingOnly":true,"foldingRangeKind":{"valueSet":["comment","imports","region"]},"foldingRange":{"collapsedText":false}},"declaration":{"dynamicRegistration":true,"linkSupport":true},"selectionRange":{"dynamicRegistration":true},"callHierarchy":{"dynamicRegistration":true},"semanticTokens":{"dynamicRegistration":true,"tokenTypes":["namespace","type","class","enum","interface","struct","typeParameter","parameter","variable","property","enumMember","event","function","method","macro","keyword","modifier","comment","string","number","regexp","operator","decorator"],"tokenModifiers":["declaration","definition","readonly","static","deprecated","abstract","async","modification","documentation","defaultLibrary"],"formats":["relative"],"requests":{"range":true,"full":{"delta":true}},"multilineTokenSupport":false,"overlappingTokenSupport":false,"serverCancelSupport":true,"augmentsSyntaxTokens":true},"linkedEditingRange":{"dynamicRegistration":true},"typeHierarchy":{"dynamicRegistration":true},"inlineValue":{"dynamicRegistration":true},"inlayHint":{"dynamicRegistration":true,"resolveSupport":{"properties":["tooltip","textEdits","label.tooltip","label.location","label.command"]}},"diagnostic":{"dynamicRegistration":true,"relatedDocumentSupport":false}},"window":{"showMessage":{"messageActionItem":{"additionalPropertiesSupport":true}},"showDocument":{"support":true},"workDoneProgress":true},"general":{"staleRequestSupport":{"cancel":true,"retryOnContentModified":["textDocument/semanticTokens/full","textDocument/semanticTokens/range","textDocument/semanticTokens/full/delta"]},"regularExpressions":{"engine":"ECMAScript","version":"ES2020"},"markdown":{"parser":"marked","version":"1.1.0"},"positionEncodings":["utf-16"]},"notebookDocument":{"synchronization":{"dynamicRegistration":true,"executionSummarySupport":true}}},"initializationOptions":{"usePlaceholders":true,"completionDocumentation":true,"verboseOutput":false,"build.directoryFilters":["-foof","-internal/protocol/typescript"],"codelenses":{"reference":true,"gc_details":true},"analyses":{"fillstruct":true,"staticcheck":true,"unusedparams":false,"composites":false},"semanticTokens":true,"noSemanticString":true,"noSemanticNumber":true,"templateExtensions":["tmpl","gotmpl"],"ui.completion.matcher":"Fuzzy","ui.inlayhint.hints":{"assignVariableTypes":false,"compositeLiteralFields":false,"compositeLiteralTypes":false,"constantValues":false,"functionTypeParameters":false,"parameterNames":false,"rangeVariableTypes":false},"ui.vulncheck":"Off","allExperiments":true},"trace":"off","workspaceFolders":[{"uri":"file:///Users/pjw/hakim","name":"hakim"}]}`

type DiffReporter struct {
	path  cmp.Path
	diffs []string
}

func (r *DiffReporter) PushStep(ps cmp.PathStep) {
	r.path = append(r.path, ps)
}

func (r *DiffReporter) Report(rs cmp.Result) {
	if !rs.Equal() {
		vx, vy := r.path.Last().Values()
		r.diffs = append(r.diffs, fmt.Sprintf("%#v:\n\t-: %+v\n\t+: %+v\n", r.path, vx, vy))
	}
}

func (r *DiffReporter) PopStep() {
	r.path = r.path[:len(r.path)-1]
}

func (r *DiffReporter) String() string {
	return strings.Join(r.diffs, "\n")
}

func TestStringChanges(t *testing.T) {
	// string as value
	stringLeaf := regexp.MustCompile(`:("[^"]*")`)
	leafs := stringLeaf.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, leafs, "23", "true")
	// string as first element of array
	stringArray := regexp.MustCompile(`[[]("[^"]*")`)
	arrays := stringArray.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, arrays, "23", "true")
}

func TestBoolChanges(t *testing.T) {
	boolLeaf := regexp.MustCompile(`:(true|false)(,|})`)
	leafs := boolLeaf.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, leafs, "23", `"xx"`)
	boolArray := regexp.MustCompile(`:[[](true|false)(,|])`)
	arrays := boolArray.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, arrays, "23", `"xx"`)
}

func TestNumberChanges(t *testing.T) {
	numLeaf := regexp.MustCompile(`:(\d+)(,|})`)
	leafs := numLeaf.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, leafs, "true", `"xx"`)
	numArray := regexp.MustCompile(`:[[](\d+)(,|])`)
	arrays := numArray.FindAllStringSubmatchIndex(input, -1)
	allDeltas(t, arrays, "true", `"xx"`)
}

// v is a set of matches. check that substituting any repl never
// creates more than 1 unmarshaling error
func allDeltas(t *testing.T, v [][]int, repls ...string) {
	t.Helper()
	for _, repl := range repls {
		for i, x := range v {
			err := tryChange(x[2], x[3], repl)
			if err != nil {
				t.Errorf("%d:%q %v", i, input[x[2]:x[3]], err)
			}
		}
	}
}

func tryChange(start, end int, repl string) error {
	var p, q protocol.ParamInitialize
	mod := input[:start] + repl + input[end:]
	excerpt := func() (string, string) {
		a := max(start-5, 0)
		// trusting repl to be no longer than what it replaces
		b := min(end+5, len(input))
		ma := input[a:b]
		mb := mod[a:b]
		return ma, mb
	}

	if err := json.Unmarshal([]byte(input), &p); err != nil {
		return fmt.Errorf("%s %v", repl, err)
	}
	switch err := json.Unmarshal([]byte(mod), &q).(type) {
	case nil: //ok
	case *json.UnmarshalTypeError:
		break
	case *protocol.UnmarshalError:
		return nil // cmp.Diff produces several diffs for custom unmrshalers
	default:
		return fmt.Errorf("%T unexpected unmarshal error", err)
	}

	var r DiffReporter
	cmp.Diff(p, q, cmp.Reporter(&r))
	if len(r.diffs) > 1 { // 0 is possible, e.g., for interface{}
		ma, mb := excerpt()
		return fmt.Errorf("got %d diffs for %q\n%s\n%s", len(r.diffs), repl, ma, mb)
	}
	return nil
}


================================================
FILE: gopls/internal/protocol/log.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"context"
	"fmt"
	"io"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/internal/jsonrpc2"
)

type loggingStream struct {
	stream jsonrpc2.Stream
	logMu  sync.Mutex
	log    io.Writer
}

// LoggingStream returns a stream that does LSP protocol logging too
func LoggingStream(str jsonrpc2.Stream, w io.Writer) jsonrpc2.Stream {
	return &loggingStream{stream: str, log: w}
}

func (s *loggingStream) Read(ctx context.Context) (jsonrpc2.Message, int64, error) {
	msg, count, err := s.stream.Read(ctx)
	if err == nil {
		s.logCommon(msg, true)
	}
	return msg, count, err
}

func (s *loggingStream) Write(ctx context.Context, msg jsonrpc2.Message) (int64, error) {
	s.logCommon(msg, false)
	count, err := s.stream.Write(ctx, msg)
	return count, err
}

func (s *loggingStream) Close() error {
	return s.stream.Close()
}

type req struct {
	method string
	start  time.Time
}

type mapped struct {
	mu          sync.Mutex
	clientCalls map[string]req
	serverCalls map[string]req
}

var maps = &mapped{
	sync.Mutex{},
	make(map[string]req),
	make(map[string]req),
}

// these 4 methods are each used exactly once, but it seemed
// better to have the encapsulation rather than ad hoc mutex
// code in 4 places
func (m *mapped) client(id string) req {
	m.mu.Lock()
	defer m.mu.Unlock()
	v := m.clientCalls[id]
	delete(m.clientCalls, id)
	return v
}

func (m *mapped) server(id string) req {
	m.mu.Lock()
	defer m.mu.Unlock()
	v := m.serverCalls[id]
	delete(m.serverCalls, id)
	return v
}

func (m *mapped) setClient(id string, r req) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.clientCalls[id] = r
}

func (m *mapped) setServer(id string, r req) {
	m.mu.Lock()
	defer m.mu.Unlock()
	m.serverCalls[id] = r
}

const eor = "\r\n\r\n\r\n"

func (s *loggingStream) logCommon(msg jsonrpc2.Message, isRead bool) {
	s.logMu.Lock()
	defer s.logMu.Unlock()
	direction, pastTense := "Received", "Received"
	get, set := maps.client, maps.setServer
	if isRead {
		direction, pastTense = "Sending", "Sent"
		get, set = maps.server, maps.setClient
	}
	if msg == nil || s.log == nil {
		return
	}
	tm := time.Now()
	tmfmt := tm.Format("15:04:05.000 PM")

	buf := strings.Builder{}
	fmt.Fprintf(&buf, "[Trace - %s] ", tmfmt) // common beginning
	switch msg := msg.(type) {
	case *jsonrpc2.Call:
		id := fmt.Sprint(msg.ID())
		fmt.Fprintf(&buf, "%s request '%s - (%s)'.\n", direction, msg.Method(), id)
		fmt.Fprintf(&buf, "Params: %s%s", msg.Params(), eor)
		set(id, req{method: msg.Method(), start: tm})
	case *jsonrpc2.Notification:
		fmt.Fprintf(&buf, "%s notification '%s'.\n", direction, msg.Method())
		fmt.Fprintf(&buf, "Params: %s%s", msg.Params(), eor)
	case *jsonrpc2.Response:
		id := fmt.Sprint(msg.ID())
		if err := msg.Err(); err != nil {
			fmt.Fprintf(s.log, "[Error - %s] %s #%s %s%s", pastTense, tmfmt, id, err, eor)
			return
		}
		cc := get(id)
		elapsed := tm.Sub(cc.start)
		fmt.Fprintf(&buf, "%s response '%s - (%s)' in %dms.\n",
			direction, cc.method, id, elapsed/time.Millisecond)
		fmt.Fprintf(&buf, "Result: %s%s", msg.Result(), eor)
	}
	s.log.Write([]byte(buf.String()))
}


================================================
FILE: gopls/internal/protocol/mapper.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

// This file defines Mapper, which wraps a file content buffer
// ([]byte) and provides efficient conversion between every kind of
// position representation.
//
// gopls uses four main representations of position:
//
// 1. byte offsets, e.g. (start, end int), starting from zero.
//
// 2. go/token notation. Use these types when interacting directly
//    with the go/* syntax packages:
//
// 	token.Pos
// 	token.FileSet
// 	token.File
//
//    Because File.Offset and File.Pos panic on invalid inputs,
//    we do not call them directly and instead use the safetoken package
//    for these conversions. This is enforced by a static check.
//
//    Beware also that the methods of token.File have two bugs for which
//    safetoken contains workarounds:
//    - #57490, whereby the parser may create ast.Nodes during error
//      recovery whose computed positions are out of bounds (EOF+1).
//    - #41029, whereby the wrong line number is returned for the EOF position.
//
// 3. the cmd package.
//
//    cmd.point = (line, col8, offset).
//    cmd.Span = (uri URI, start, end cmd.point)
//
//          Line and column are 1-based.
//          Columns are measured in bytes (UTF-8 codes).
//          All fields are optional.
//
//    These types are useful as intermediate conversions of validated
//    ranges. Since their fields are optional they are also useful for
//    parsing user-provided positions (e.g. in the CLI) before we have
//    access to file contents.
//
// 4. protocol, the LSP RPC message format.
//
//    protocol.Position = (Line, Character uint32)
//    protocol.Range = (start, end Position)
//    protocol.Location = (URI, protocol.Range)
//
//          Line and Character are 0-based.
//          Characters (columns) are measured in UTF-16 codes.
//
//    protocol.Mapper holds the (URI, Content) of a file, enabling
//    efficient mapping between byte offsets, cmd ranges, and
//    protocol ranges.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/token"
	"sort"
	"sync"
	"unicode/utf8"

	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
)

// A Mapper wraps the content of a file and provides mapping
// between byte offsets and notations of position such as:
//
//   - (line, col8) pairs, where col8 is a 1-based UTF-8 column number
//     (bytes), as used by the go/token and cmd packages.
//
//   - (line, col16) pairs, where col16 is a 1-based UTF-16 column
//     number, as used by the LSP protocol.
//
// All conversion methods are named "FromTo", where From and To are the two types.
// For example, the PointPosition method converts from a Point to a Position.
//
// Mapper does not intrinsically depend on go/token-based
// representations.  Use safetoken to map between token.Pos <=> byte
// offsets, or the convenience methods such as PosPosition,
// NodePosition, or NodeRange.
//
// See overview comments at top of this file.
type Mapper struct {
	URI     DocumentURI
	Content []byte

	// Line-number information is requested only for a tiny
	// fraction of Mappers, so we compute it lazily.
	// Call initLines() before accessing fields below.
	linesOnce sync.Once
	lineStart []int // byte offset of start of ith line (0-based); last=EOF iff \n-terminated
	nonASCII  bool

	// TODO(adonovan): adding an extra lineStart entry for EOF
	// might simplify every method that accesses it. Try it out.
}

// NewMapper creates a new mapper for the given URI and content.
func NewMapper(uri DocumentURI, content []byte) *Mapper {
	return &Mapper{URI: uri, Content: content}
}

// initLines populates the lineStart table.
func (m *Mapper) initLines() {
	m.linesOnce.Do(func() {
		nlines := bytes.Count(m.Content, []byte("\n"))
		m.lineStart = make([]int, 1, nlines+1) // initially []int{0}
		for offset, b := range m.Content {
			if b == '\n' {
				m.lineStart = append(m.lineStart, offset+1)
			}
			if b >= utf8.RuneSelf {
				m.nonASCII = true
			}
		}
	})
}

// LineCol8Position converts a valid line and UTF-8 column number,
// both 1-based, to a protocol (UTF-16) position.
func (m *Mapper) LineCol8Position(line, col8 int) (Position, error) {
	// Report a bug for inputs that are invalid for any file content.
	if line < 1 {
		return Position{}, bug.Errorf("invalid 1-based line number: %d", line)
	}
	if col8 < 1 {
		return Position{}, bug.Errorf("invalid 1-based column number: %d", col8)
	}

	m.initLines()
	line0 := line - 1 // 0-based
	if !(0 <= line0 && line0 < len(m.lineStart)) {
		return Position{}, fmt.Errorf("line number %d out of range (max %d)", line, len(m.lineStart))
	}

	// content[start:end] is the preceding partial line.
	start := m.lineStart[line0]
	end := start + col8 - 1

	// Validate column.
	if end > len(m.Content) {
		return Position{}, fmt.Errorf("column is beyond end of file")
	} else if line0+1 < len(m.lineStart) && end >= m.lineStart[line0+1] {
		return Position{}, fmt.Errorf("column is beyond end of line")
	}

	char := UTF16Len(m.Content[start:end])
	return Position{Line: uint32(line0), Character: uint32(char)}, nil
}

// -- conversions from byte offsets --

// OffsetLocation converts a byte-offset interval to a protocol (UTF-16) location.
func (m *Mapper) OffsetLocation(start, end int) (Location, error) {
	rng, err := m.OffsetRange(start, end)
	if err != nil {
		return Location{}, err
	}
	return m.URI.Location(rng), nil
}

// OffsetRange converts a byte-offset interval to a protocol (UTF-16) range.
func (m *Mapper) OffsetRange(start, end int) (Range, error) {
	if start > end {
		return Range{}, fmt.Errorf("start offset (%d) > end (%d)", start, end)
	}
	startPosition, err := m.OffsetPosition(start)
	if err != nil {
		return Range{}, fmt.Errorf("start: %v", err)
	}
	endPosition, err := m.OffsetPosition(end)
	if err != nil {
		return Range{}, fmt.Errorf("end: %v", err)
	}
	return Range{Start: startPosition, End: endPosition}, nil
}

// OffsetPosition converts a byte offset to a protocol (UTF-16) position.
func (m *Mapper) OffsetPosition(offset int) (Position, error) {
	if !(0 <= offset && offset <= len(m.Content)) {
		return Position{}, fmt.Errorf("invalid offset %d (want 0-%d)", offset, len(m.Content))
	}
	// No error may be returned after this point,
	// even if the offset does not fall at a rune boundary.

	line, col16 := m.lineCol16(offset)
	return Position{Line: uint32(line), Character: uint32(col16)}, nil
}

// lineCol16 converts a valid byte offset to line and UTF-16 column numbers, both 0-based.
func (m *Mapper) lineCol16(offset int) (int, int) {
	line, start, cr := m.line(offset)
	var col16 int
	if m.nonASCII {
		col16 = UTF16Len(m.Content[start:offset])
	} else {
		col16 = offset - start
	}
	if cr {
		col16-- // retreat from \r at line end
	}
	return line, col16
}

// OffsetLineCol8 converts a valid byte offset to line and UTF-8 column numbers, both 1-based.
func (m *Mapper) OffsetLineCol8(offset int) (int, int) {
	line, start, cr := m.line(offset)
	col8 := offset - start
	if cr {
		col8-- // retreat from \r at line end
	}
	return line + 1, col8 + 1
}

// line returns:
// - the 0-based index of the line that encloses the (valid) byte offset;
// - the start offset of that line; and
// - whether the offset denotes a carriage return (\r) at line end.
func (m *Mapper) line(offset int) (int, int, bool) {
	m.initLines()
	// In effect, binary search returns a 1-based result.
	line := sort.Search(len(m.lineStart), func(i int) bool {
		return offset < m.lineStart[i]
	})

	// Adjustment for line-endings: \r|\n is the same as |\r\n.
	var eol int
	if line == len(m.lineStart) {
		eol = len(m.Content) // EOF
	} else {
		eol = m.lineStart[line] - 1
	}
	cr := offset == eol && offset > 0 && m.Content[offset-1] == '\r'

	line-- // 0-based

	return line, m.lineStart[line], cr
}

// -- conversions from protocol (UTF-16) domain --

// RangeOffsets converts a protocol (UTF-16) range to start/end byte offsets.
func (m *Mapper) RangeOffsets(r Range) (int, int, error) {
	start, err := m.PositionOffset(r.Start)
	if err != nil {
		return 0, 0, err
	}
	end, err := m.PositionOffset(r.End)
	if err != nil {
		return 0, 0, err
	}
	if start > end {
		return 0, 0, fmt.Errorf("start (offset %d) > end (offset %d)", start, end)
	}
	return start, end, nil
}

// PositionOffset converts a protocol (UTF-16) position to a byte offset.
func (m *Mapper) PositionOffset(p Position) (int, error) {
	m.initLines()

	// Validate line number.
	if p.Line > uint32(len(m.lineStart)) {
		return 0, fmt.Errorf("line number %d out of range 0-%d", p.Line, len(m.lineStart))
	} else if p.Line == uint32(len(m.lineStart)) {
		if p.Character == 0 {
			return len(m.Content), nil // EOF
		}
		return 0, fmt.Errorf("column is beyond end of file")
	}

	offset := m.lineStart[p.Line]
	content := m.Content[offset:] // rest of file from start of enclosing line

	// Advance bytes up to the required number of UTF-16 codes.
	col8 := 0
	for col16 := 0; col16 < int(p.Character); col16++ {
		r, sz := utf8.DecodeRune(content)
		if sz == 0 {
			return 0, fmt.Errorf("column is beyond end of file")
		}
		if r == '\n' {
			return 0, fmt.Errorf("column is beyond end of line")
		}
		if sz == 1 && r == utf8.RuneError {
			return 0, fmt.Errorf("buffer contains invalid UTF-8 text")
		}
		content = content[sz:]

		if r >= 0x10000 {
			col16++ // rune was encoded by a pair of surrogate UTF-16 codes

			if col16 == int(p.Character) {
				break // requested position is in the middle of a rune
			}
		}
		col8 += sz
	}
	return offset + col8, nil
}

// -- go/token domain convenience methods --

// PosPosition converts a token pos to a protocol (UTF-16) position.
func (m *Mapper) PosPosition(tf *token.File, pos token.Pos) (Position, error) {
	offset, err := safetoken.Offset(tf, pos)
	if err != nil {
		return Position{}, err
	}
	return m.OffsetPosition(offset)
}

// PosLocation converts a token range to a protocol (UTF-16) location.
func (m *Mapper) PosLocation(tf *token.File, start, end token.Pos) (Location, error) {
	startOffset, endOffset, err := safetoken.Offsets(tf, start, end)
	if err != nil {
		return Location{}, err
	}
	rng, err := m.OffsetRange(startOffset, endOffset)
	if err != nil {
		return Location{}, err
	}
	return m.URI.Location(rng), nil
}

// PosRange converts a token range to a protocol (UTF-16) range.
func (m *Mapper) PosRange(tf *token.File, start, end token.Pos) (Range, error) {
	startOffset, endOffset, err := safetoken.Offsets(tf, start, end)
	if err != nil {
		return Range{}, err
	}
	return m.OffsetRange(startOffset, endOffset)
}

// PosText returns the source text for the token range.
func (m *Mapper) PosText(tf *token.File, start, end token.Pos) ([]byte, error) {
	startOffset, endOffset, err := safetoken.Offsets(tf, start, end)
	if err != nil {
		return nil, err
	}
	return m.Content[startOffset:endOffset], nil
}

// NodeRange converts a syntax node range to a protocol (UTF-16) range.
func (m *Mapper) NodeRange(tf *token.File, node ast.Node) (Range, error) {
	return m.PosRange(tf, node.Pos(), node.End())
}

// NodeText returns the source text for syntax node range.
func (m *Mapper) NodeText(tf *token.File, node ast.Node) ([]byte, error) {
	return m.PosText(tf, node.Pos(), node.End())
}

// LocationTextDocumentPositionParams converts its argument to its result.
func LocationTextDocumentPositionParams(loc Location) TextDocumentPositionParams {
	return TextDocumentPositionParams{
		TextDocument: TextDocumentIdentifier{URI: loc.URI},
		Range:        loc.Range,
		Position:     loc.Range.Start, // not used
	}
}


================================================
FILE: gopls/internal/protocol/mapper_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol_test

import (
	"fmt"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

// This file tests Mapper's logic for converting between offsets,
// UTF-8 columns, and UTF-16 columns. (The strange form attests to
// earlier abstractions.)

// 𐐀 is U+10400 = [F0 90 90 80] in UTF-8, [D801 DC00] in UTF-16.
var funnyString = []byte("𐐀23\n𐐀45")

var toUTF16Tests = []struct {
	scenario    string
	input       []byte
	line        int    // 1-indexed count
	col         int    // 1-indexed byte position in line
	offset      int    // 0-indexed byte offset into input
	resUTF16col int    // 1-indexed UTF-16 col number
	pre         string // everything before the cursor on the line
	post        string // everything from the cursor onwards
	err         string // expected error string in call to ToUTF16Column
	issue       *bool
}{
	{
		scenario: "cursor missing content",
		input:    nil,
		offset:   -1,
		err:      "point has neither offset nor line/column",
	},
	{
		scenario: "cursor missing position",
		input:    funnyString,
		line:     -1,
		col:      -1,
		offset:   -1,
		err:      "point has neither offset nor line/column",
	},
	{
		scenario:    "zero length input; cursor at first col, first line",
		input:       []byte(""),
		line:        1,
		col:         1,
		offset:      0,
		resUTF16col: 1,
	},
	{
		scenario:    "cursor before funny character; first line",
		input:       funnyString,
		line:        1,
		col:         1,
		offset:      0,
		resUTF16col: 1,
		pre:         "",
		post:        "𐐀23",
	},
	{
		scenario:    "cursor after funny character; first line",
		input:       funnyString,
		line:        1,
		col:         5, // 4 + 1 (1-indexed)
		offset:      4, // (unused since we have line+col)
		resUTF16col: 3, // 2 + 1 (1-indexed)
		pre:         "𐐀",
		post:        "23",
	},
	{
		scenario:    "cursor after last character on first line",
		input:       funnyString,
		line:        1,
		col:         7, // 4 + 1 + 1 + 1 (1-indexed)
		offset:      6, // 4 + 1 + 1 (unused since we have line+col)
		resUTF16col: 5, // 2 + 1 + 1 + 1 (1-indexed)
		pre:         "𐐀23",
		post:        "",
	},
	{
		scenario:    "cursor before funny character; second line",
		input:       funnyString,
		line:        2,
		col:         1,
		offset:      7, // length of first line (unused since we have line+col)
		resUTF16col: 1,
		pre:         "",
		post:        "𐐀45",
	},
	{
		scenario:    "cursor after funny character; second line",
		input:       funnyString,
		line:        1,
		col:         5,  // 4 + 1 (1-indexed)
		offset:      11, // 7 (length of first line) + 4 (unused since we have line+col)
		resUTF16col: 3,  // 2 + 1 (1-indexed)
		pre:         "𐐀",
		post:        "45",
	},
	{
		scenario:    "cursor after last character on second line",
		input:       funnyString,
		line:        2,
		col:         7,  // 4 + 1 + 1 + 1 (1-indexed)
		offset:      13, // 7 (length of first line) + 4 + 1 + 1 (unused since we have line+col)
		resUTF16col: 5,  // 2 + 1 + 1 + 1 (1-indexed)
		pre:         "𐐀45",
		post:        "",
	},
	{
		scenario: "cursor beyond end of file",
		input:    funnyString,
		line:     2,
		col:      8,  // 4 + 1 + 1 + 1 + 1 (1-indexed)
		offset:   14, // 4 + 1 + 1 + 1 (unused since we have line+col)
		err:      "column is beyond end of file",
	},
}

var fromUTF16Tests = []struct {
	scenario  string
	input     []byte
	line      int    // 1-indexed line number (isn't actually used)
	utf16col  int    // 1-indexed UTF-16 col number
	resCol    int    // 1-indexed byte position in line
	resOffset int    // 0-indexed byte offset into input
	pre       string // everything before the cursor on the line
	post      string // everything from the cursor onwards
	err       string // expected error string in call to ToUTF16Column
}{
	{
		scenario:  "zero length input; cursor at first col, first line",
		input:     []byte(""),
		line:      1,
		utf16col:  1,
		resCol:    1,
		resOffset: 0,
		pre:       "",
		post:      "",
	},
	{
		scenario:  "cursor before funny character",
		input:     funnyString,
		line:      1,
		utf16col:  1,
		resCol:    1,
		resOffset: 0,
		pre:       "",
		post:      "𐐀23",
	},
	{
		scenario:  "cursor after funny character",
		input:     funnyString,
		line:      1,
		utf16col:  3,
		resCol:    5,
		resOffset: 4,
		pre:       "𐐀",
		post:      "23",
	},
	{
		scenario:  "cursor after last character on line",
		input:     funnyString,
		line:      1,
		utf16col:  5,
		resCol:    7,
		resOffset: 6,
		pre:       "𐐀23",
		post:      "",
	},
	{
		scenario:  "cursor beyond last character on line",
		input:     funnyString,
		line:      1,
		utf16col:  6,
		resCol:    7,
		resOffset: 6,
		pre:       "𐐀23",
		post:      "",
		err:       "column is beyond end of line",
	},
	{
		scenario:  "cursor before funny character; second line",
		input:     funnyString,
		line:      2,
		utf16col:  1,
		resCol:    1,
		resOffset: 7,
		pre:       "",
		post:      "𐐀45",
	},
	{
		scenario:  "cursor after funny character; second line",
		input:     funnyString,
		line:      2,
		utf16col:  3,  // 2 + 1 (1-indexed)
		resCol:    5,  // 4 + 1 (1-indexed)
		resOffset: 11, // 7 (length of first line) + 4
		pre:       "𐐀",
		post:      "45",
	},
	{
		scenario:  "cursor after last character on second line",
		input:     funnyString,
		line:      2,
		utf16col:  5,  // 2 + 1 + 1 + 1 (1-indexed)
		resCol:    7,  // 4 + 1 + 1 + 1 (1-indexed)
		resOffset: 13, // 7 (length of first line) + 4 + 1 + 1
		pre:       "𐐀45",
		post:      "",
	},
	{
		scenario:  "cursor beyond end of file",
		input:     funnyString,
		line:      2,
		utf16col:  6,  // 2 + 1 + 1 + 1 + 1(1-indexed)
		resCol:    8,  // 4 + 1 + 1 + 1 + 1 (1-indexed)
		resOffset: 14, // 7 (length of first line) + 4 + 1 + 1 + 1
		err:       "column is beyond end of file",
	},
}

func TestToUTF16(t *testing.T) {
	for _, e := range toUTF16Tests {
		t.Run(e.scenario, func(t *testing.T) {
			if e.issue != nil && !*e.issue {
				t.Skip("expected to fail")
			}
			m := protocol.NewMapper("", e.input)
			var pos protocol.Position
			var err error
			if e.line > 0 {
				pos, err = m.LineCol8Position(e.line, e.col)
			} else if e.offset >= 0 {
				pos, err = m.OffsetPosition(e.offset)
			} else {
				err = fmt.Errorf("point has neither offset nor line/column")
			}
			if err != nil {
				if err.Error() != e.err {
					t.Fatalf("expected error %v; got %v", e.err, err)
				}
				return
			}
			if e.err != "" {
				t.Fatalf("unexpected success; wanted %v", e.err)
			}
			got := int(pos.Character) + 1
			if got != e.resUTF16col {
				t.Fatalf("expected result %v; got %v", e.resUTF16col, got)
			}
			pre, post := getPrePost(e.input, e.offset)
			if pre != e.pre {
				t.Fatalf("expected #%d pre %q; got %q", e.offset, e.pre, pre)
			}
			if post != e.post {
				t.Fatalf("expected #%d, post %q; got %q", e.offset, e.post, post)
			}
		})
	}
}

func TestFromUTF16(t *testing.T) {
	for _, e := range fromUTF16Tests {
		t.Run(e.scenario, func(t *testing.T) {
			m := protocol.NewMapper("", e.input)
			offset, err := m.PositionOffset(protocol.Position{
				Line:      uint32(e.line - 1),
				Character: uint32(e.utf16col - 1),
			})
			if err != nil {
				if err.Error() != e.err {
					t.Fatalf("expected error %v; got %v", e.err, err)
				}
				return
			}
			if e.err != "" {
				t.Fatalf("unexpected success; wanted %v", e.err)
			}
			if offset != e.resOffset {
				t.Fatalf("expected offset %v; got %v", e.resOffset, offset)
			}
			line, col8 := m.OffsetLineCol8(offset)
			if line != e.line {
				t.Fatalf("expected resulting line %v; got %v", e.line, line)
			}
			if col8 != e.resCol {
				t.Fatalf("expected resulting col %v; got %v", e.resCol, col8)
			}
			pre, post := getPrePost(e.input, offset)
			if pre != e.pre {
				t.Fatalf("expected #%d pre %q; got %q", offset, e.pre, pre)
			}
			if post != e.post {
				t.Fatalf("expected #%d post %q; got %q", offset, e.post, post)
			}
		})
	}
}

func getPrePost(content []byte, offset int) (string, string) {
	pre, post := string(content)[:offset], string(content)[offset:]
	if i := strings.LastIndex(pre, "\n"); i >= 0 {
		pre = pre[i+1:]
	}
	if i := strings.IndexRune(post, '\n'); i >= 0 {
		post = post[:i]
	}
	return pre, post
}

// -- these are the historical lsppos tests --

type testCase struct {
	content            string // input text
	substrOrOffset     any    // explicit integer offset, or a substring
	wantLine, wantChar int    // expected LSP position information
}

// offset returns the test case byte offset
func (c testCase) offset() int {
	switch x := c.substrOrOffset.(type) {
	case int:
		return x
	case string:
		i := strings.Index(c.content, x)
		if i < 0 {
			panic(fmt.Sprintf("%q does not contain substring %q", c.content, x))
		}
		return i
	}
	panic("substrOrIndex must be an integer or string")
}

var tests = []testCase{
	{"a𐐀b", "a", 0, 0},
	{"a𐐀b", "𐐀", 0, 1},
	{"a𐐀b", "b", 0, 3},
	{"a𐐀b\n", "\n", 0, 4},
	{"a𐐀b\r\n", "\n", 0, 4}, // \r|\n is not a valid position, so we move back to the end of the first line.
	{"a𐐀b\r\nx", "x", 1, 0},
	{"a𐐀b\r\nx\ny", "y", 2, 0},

	// Testing EOL and EOF positions
	{"", 0, 0, 0}, // 0th position of an empty buffer is (0, 0)
	{"abc", "c", 0, 2},
	{"abc", 3, 0, 3},
	{"abc\n", "\n", 0, 3},
	{"abc\n", 4, 1, 0}, // position after a newline is on the next line
}

func TestLineChar(t *testing.T) {
	for _, test := range tests {
		m := protocol.NewMapper("", []byte(test.content))
		offset := test.offset()
		posn, _ := m.OffsetPosition(offset)
		gotLine, gotChar := int(posn.Line), int(posn.Character)
		if gotLine != test.wantLine || gotChar != test.wantChar {
			t.Errorf("LineChar(%d) = (%d,%d), want (%d,%d)", offset, gotLine, gotChar, test.wantLine, test.wantChar)
		}
	}
}

func TestInvalidOffset(t *testing.T) {
	content := []byte("a𐐀b\r\nx\ny")
	m := protocol.NewMapper("", content)
	for _, offset := range []int{-1, 100} {
		posn, err := m.OffsetPosition(offset)
		if err == nil {
			t.Errorf("OffsetPosition(%d) = %s, want error", offset, posn)
		}
	}
}

func TestPosition(t *testing.T) {
	for _, test := range tests {
		m := protocol.NewMapper("", []byte(test.content))
		offset := test.offset()
		got, err := m.OffsetPosition(offset)
		if err != nil {
			t.Errorf("OffsetPosition(%d) failed: %v", offset, err)
			continue
		}
		want := protocol.Position{Line: uint32(test.wantLine), Character: uint32(test.wantChar)}
		if got != want {
			t.Errorf("Position(%d) = %v, want %v", offset, got, want)
		}
	}
}

func TestRange(t *testing.T) {
	for _, test := range tests {
		m := protocol.NewMapper("", []byte(test.content))
		offset := test.offset()
		got, err := m.OffsetRange(0, offset)
		if err != nil {
			t.Fatal(err)
		}
		want := protocol.Range{
			End: protocol.Position{Line: uint32(test.wantLine), Character: uint32(test.wantChar)},
		}
		if got != want {
			t.Errorf("Range(%d) = %v, want %v", offset, got, want)
		}
	}
}

func TestBytesOffset(t *testing.T) {
	tests := []struct {
		text string
		pos  protocol.Position
		want int
	}{
		// U+10400 encodes as [F0 90 90 80] in UTF-8 and [D801 DC00] in UTF-16.
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 0}, want: 0},
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 1}, want: 1},
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 2}, want: 1},
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 3}, want: 5},
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 4}, want: 6},
		{text: `a𐐀b`, pos: protocol.Position{Line: 0, Character: 5}, want: -1},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 0, Character: 3}, want: 3},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 0, Character: 4}, want: -1},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 1, Character: 0}, want: 4},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 1, Character: 3}, want: 7},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 1, Character: 4}, want: -1},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 2, Character: 0}, want: 8},
		{text: "aaa\nbbb\n", pos: protocol.Position{Line: 2, Character: 1}, want: -1},
		{text: "aaa\nbbb\n\n", pos: protocol.Position{Line: 2, Character: 0}, want: 8},
	}

	for i, test := range tests {
		fname := fmt.Sprintf("test %d", i)
		uri := protocol.URIFromPath(fname)
		mapper := protocol.NewMapper(uri, []byte(test.text))
		got, err := mapper.PositionOffset(test.pos)
		if err != nil && test.want != -1 {
			t.Errorf("%d: unexpected error: %v", i, err)
		}
		if err == nil && got != test.want {
			t.Errorf("want %d for %q(Line:%d,Character:%d), but got %d", test.want, test.text, int(test.pos.Line), int(test.pos.Character), got)
		}
	}
}


================================================
FILE: gopls/internal/protocol/protocol.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
	jsonrpc2_v2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/xcontext"
)

var (
	// RequestCancelledError should be used when a request is cancelled early.
	RequestCancelledError   = jsonrpc2.NewError(-32800, "JSON RPC cancelled")
	RequestCancelledErrorV2 = jsonrpc2_v2.NewError(-32800, "JSON RPC cancelled")
)

type ClientCloser interface {
	Client
	io.Closer
}

type connSender interface {
	io.Closer

	Notify(ctx context.Context, method string, params any) error
	Call(ctx context.Context, method string, params, result any) error
}

type clientDispatcher struct {
	sender connSender
}

func (c *clientDispatcher) Close() error {
	return c.sender.Close()
}

// ClientDispatcher returns a Client that dispatches LSP requests across the
// given jsonrpc2 connection.
func ClientDispatcher(conn jsonrpc2.Conn) ClientCloser {
	return &clientDispatcher{sender: clientConn{conn}}
}

type clientConn struct {
	conn jsonrpc2.Conn
}

func (c clientConn) Close() error {
	return c.conn.Close()
}

func (c clientConn) Notify(ctx context.Context, method string, params any) error {
	return c.conn.Notify(ctx, method, params)
}

func (c clientConn) Call(ctx context.Context, method string, params any, result any) error {
	id, err := c.conn.Call(ctx, method, params, result)
	if ctx.Err() != nil {
		cancelCall(ctx, c, id)
	}
	return err
}

func ClientDispatcherV2(conn *jsonrpc2_v2.Connection) ClientCloser {
	return &clientDispatcher{clientConnV2{conn}}
}

type clientConnV2 struct {
	conn *jsonrpc2_v2.Connection
}

func (c clientConnV2) Close() error {
	return c.conn.Close()
}

func (c clientConnV2) Notify(ctx context.Context, method string, params any) error {
	return c.conn.Notify(ctx, method, params)
}

func (c clientConnV2) Call(ctx context.Context, method string, params any, result any) error {
	call := c.conn.Call(ctx, method, params)
	err := call.Await(ctx, result)
	if ctx.Err() != nil {
		detached := xcontext.Detach(ctx)
		c.conn.Notify(detached, "$/cancelRequest", &CancelParams{ID: call.ID().Raw()})
	}
	return err
}

// ServerDispatcher returns a Server that dispatches LSP requests across the
// given jsonrpc2 connection.
func ServerDispatcher(conn jsonrpc2.Conn) Server {
	return &serverDispatcher{sender: clientConn{conn}}
}

func ServerDispatcherV2(conn *jsonrpc2_v2.Connection) Server {
	return &serverDispatcher{sender: clientConnV2{conn}}
}

type serverDispatcher struct {
	sender connSender
}

func ClientHandler(client Client, handler jsonrpc2.Handler) jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
		if ctx.Err() != nil {
			ctx := xcontext.Detach(ctx)
			return reply(ctx, nil, RequestCancelledError)
		}
		handled, err := clientDispatch(ctx, client, reply, req)
		if handled || err != nil {
			return err
		}
		return handler(ctx, reply, req)
	}
}

func ClientHandlerV2(client Client) jsonrpc2_v2.Handler {
	return jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
		if ctx.Err() != nil {
			return nil, RequestCancelledErrorV2
		}
		req1 := req2to1(req)
		var (
			result any
			resErr error
		)
		replier := func(_ context.Context, res any, err error) error {
			if err != nil {
				resErr = err
				return nil
			}
			result = res
			return nil
		}
		_, err := clientDispatch(ctx, client, replier, req1)
		if err != nil {
			return nil, err
		}
		return result, resErr
	})
}

func ServerHandler(server Server, handler jsonrpc2.Handler) jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
		if ctx.Err() != nil {
			ctx := xcontext.Detach(ctx)
			return reply(ctx, nil, RequestCancelledError)
		}
		handled, err := serverDispatch(ctx, server, reply, req)
		if handled || err != nil {
			return err
		}
		return handler(ctx, reply, req)
	}
}

func ServerHandlerV2(server Server) jsonrpc2_v2.Handler {
	return jsonrpc2_v2.HandlerFunc(func(ctx context.Context, req *jsonrpc2_v2.Request) (any, error) {
		if ctx.Err() != nil {
			return nil, RequestCancelledErrorV2
		}
		req1 := req2to1(req)
		var (
			result any
			resErr error
		)
		replier := func(_ context.Context, res any, err error) error {
			if err != nil {
				resErr = err
				return nil
			}
			result = res
			return nil
		}
		_, err := serverDispatch(ctx, server, replier, req1)
		if err != nil {
			return nil, err
		}
		return result, resErr
	})
}

func req2to1(req2 *jsonrpc2_v2.Request) jsonrpc2.Request {
	if req2.ID.IsValid() {
		raw := req2.ID.Raw()
		var idv1 jsonrpc2.ID
		switch v := raw.(type) {
		case int64:
			idv1 = jsonrpc2.NewIntID(v)
		case string:
			idv1 = jsonrpc2.NewStringID(v)
		default:
			panic(fmt.Sprintf("unsupported ID type %T", raw))
		}
		req1, err := jsonrpc2.NewCall(idv1, req2.Method, req2.Params)
		if err != nil {
			panic(err)
		}
		return req1
	}
	req1, err := jsonrpc2.NewNotification(req2.Method, req2.Params)
	if err != nil {
		panic(err)
	}
	return req1
}

func Handlers(handler jsonrpc2.Handler) jsonrpc2.Handler {
	return CancelHandler(
		jsonrpc2.AsyncHandler(
			jsonrpc2.MustReplyHandler(handler)))
}

func CancelHandler(handler jsonrpc2.Handler) jsonrpc2.Handler {
	handler, canceller := jsonrpc2.CancelHandler(handler)
	return func(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
		if req.Method() != "$/cancelRequest" {
			// TODO(iancottrell): See if we can generate a reply for the request to be cancelled
			// at the point of cancellation rather than waiting for gopls to naturally reply.
			// To do that, we need to keep track of whether a reply has been sent already and
			// be careful about racing between the two paths.
			// TODO(iancottrell): Add a test that watches the stream and verifies the response
			// for the cancelled request flows.
			replyWithDetachedContext := func(ctx context.Context, resp any, err error) error {
				// https://microsoft.github.io/language-server-protocol/specifications/specification-current/#cancelRequest
				if ctx.Err() != nil && err == nil {
					err = RequestCancelledError
				}
				ctx = xcontext.Detach(ctx)
				return reply(ctx, resp, err)
			}
			return handler(ctx, replyWithDetachedContext, req)
		}
		var params CancelParams
		if err := UnmarshalJSON(req.Params(), &params); err != nil {
			return sendParseError(ctx, reply, err)
		}
		if n, ok := params.ID.(float64); ok {
			canceller(jsonrpc2.NewIntID(int64(n)))
		} else if s, ok := params.ID.(string); ok {
			canceller(jsonrpc2.NewStringID(s))
		} else {
			return sendParseError(ctx, reply, fmt.Errorf("request ID %v malformed", params.ID))
		}
		return reply(ctx, nil, nil)
	}
}

func Call(ctx context.Context, conn jsonrpc2.Conn, method string, params any, result any) error {
	id, err := conn.Call(ctx, method, params, result)
	if ctx.Err() != nil {
		cancelCall(ctx, clientConn{conn}, id)
	}
	return err
}

func cancelCall(ctx context.Context, sender connSender, id jsonrpc2.ID) {
	ctx = xcontext.Detach(ctx)
	ctx, done := event.Start(ctx, "protocol.canceller")
	defer done()
	// Note that only *jsonrpc2.ID implements json.Marshaler.
	sender.Notify(ctx, "$/cancelRequest", &CancelParams{ID: &id})
}

// UnmarshalJSON unmarshals msg into the variable pointed to by
// params. In JSONRPC, optional messages may be
// "null", in which case it is a no-op.
func UnmarshalJSON(msg json.RawMessage, v any) error {
	if len(msg) == 0 || bytes.Equal(msg, []byte("null")) {
		return nil
	}
	return json.Unmarshal(msg, v)
}

func sendParseError(ctx context.Context, reply jsonrpc2.Replier, err error) error {
	return reply(ctx, nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err))
}

// NonNilSlice returns x, or an empty slice if x was nil.
//
// (Many slice fields of protocol structs must be non-nil
// to avoid being encoded as JSON "null".)
func NonNilSlice[T comparable](x []T) []T {
	if x == nil {
		return []T{}
	}
	return x
}


================================================
FILE: gopls/internal/protocol/semtok/README.txt
================================================

The [LSP](https://microsoft.github.io/language-server-protocol/specifications/specification-3-17/#textDocument_semanticTokens)
specifies semantic tokens as a way of telling clients about language-specific
properties of pieces of code in a file being edited.

The client asks for a set of semantic tokens and modifiers. This note describe which ones
gopls will return, and under what circumstances. Gopls has no control over how the client
converts semantic tokens into colors (or some other visible indication). In vscode it
is possible to modify the color a theme uses by setting the `editor.semanticTokenColorCustomizations`
object. We provide a little [guidance](#Colors) later.

There are 22 semantic tokens, with 10 possible modifiers. The protocol allows each semantic
token to be used with any of the 1024 subsets of possible modifiers, but most combinations
don't make intuitive sense (although `async documentation` has a certain appeal).

The 22 semantic tokens are `namespace`, `type`, `class`, `enum`, `interface`,
		`struct`, `typeParameter`, `parameter`, `variable`, `property`, `enumMember`,
		`event`, `function`, `method`, `macro`, `keyword`, `modifier`, `comment`,
		`string`, `number`, `regexp`, `operator`.

The 10 modifiers are `declaration`, `definition`, `readonly`, `static`,
		`deprecated`, `abstract`, `async`, `modification`, `documentation`, `defaultLibrary`.

The authoritative lists are in the [specification](https://microsoft.github.io/language-server-protocol/specifications/specification-3-17/#semanticTokenTypes)

For the implementation to work correctly the client and server have to agree on the ordering
of the tokens and of the modifiers. Gopls, therefore, will only send tokens and modifiers
that the client has asked for. This document says what gopls would send if the client
asked for everything. By default, vscode asks for everything.

Gopls sends 11 token types for `.go` files and 1 for `.*tmpl` files.
Nothing is sent for any other kind of file.
This all could change. (When Go has generics, gopls will return `typeParameter`.)

For `.*tmpl` files gopls sends `macro`, and no modifiers, for each `{{`...`}}` scope.

## Semantic tokens for Go files

There are two contrasting guiding principles that might be used to decide what to mark
with semantic tokens. All clients already do some kind of syntax marking. E.g., vscode
uses a TextMate grammar. The minimal principle would send semantic tokens only for those
language features that cannot be reliably found without parsing Go and looking at types.
The maximal principle would attempt to convey as much as possible about the Go code,
using all available parsing and type information.

There is much to be said for returning minimal information, but the minimal principle is
not well-specified. Gopls has no way of knowing what the clients know about the Go program
being edited. Even in vscode the TextMate grammars can be more or less elaborate
and change over time. (Nonetheless, a minimal implementation would not return `keyword`,
`number`, `comment`, or `string`.)

The maximal position isn't particularly well-specified either. To chose one example, a
format string might have formatting codes (`%-[4].6f`), escape sequences (`\U00010604`), and regular
characters. Should these all be distinguished? One could even imagine distinguishing
different runes by their Unicode language assignment, or some other Unicode property, such as
being [confusable](http://www.unicode.org/Public/security/10.0.0/confusables.txt). While gopls does not fully adhere to such distinctions,
it does recognizes formatting directives within strings, decorating them with "format" modifiers,
providing more precise semantic highlighting in format strings.

Semantic tokens are returned for identifiers, keywords, operators, comments, and literals.
(Semantic tokens do not cover the file. They are not returned for
white space or punctuation, and there is no semantic token for labels.)
The following describes more precisely what gopls
does, with a few notes on possible alternative choices.
The references to *object* refer to the
```types.Object``` returned by the type checker. The references to *nodes* refer to the
```ast.Node``` from the parser.

1. __`keyword`__ All Go [keywords](https://golang.org/ref/spec#Keywords) are marked `keyword`.
1. __`namespace`__ All package names are marked `namespace`. In an import, if there is an
alias, it would be marked. Otherwise the last component of the import path is marked.
1. __`type`__ Objects of type ```types.TypeName``` are marked `type`. It also reports
a modifier for the top-level constructor of the object's type, one of:
`interface`, `struct`, `signature`, `pointer`, `array`, `map`, `slice`, `chan`, `string`, `number`, `bool`, `invalid`.
1. __`parameter`__ The formal arguments in ```ast.FuncDecl``` and ```ast.FuncType``` nodes are marked `parameter`.
1. __`variable`__  Identifiers in the
scope of ```const``` are modified with `readonly`. ```nil``` is usually a `variable` modified with both
`readonly` and `defaultLibrary`. (```nil``` is a predefined identifier; the user can redefine it,
in which case it would just be a variable, or whatever.) Identifiers of type ```types.Variable``` are,
not surprisingly, marked `variable`. Identifiers being defined (node ```ast.GenDecl```) are modified
by `definition` and, if appropriate, `readonly`. Receivers (in method declarations) are
`variable`.
1. __`method`__ Methods are marked at their definition (```func (x foo) bar() {}```) or declaration
in an ```interface```. Methods are not marked where they are used.
In ```x.bar()```, ```x``` will be marked
either as a `namespace` if it is a package name, or as a `variable` if it is an interface value,
so distinguishing ```bar``` seemed superfluous.
1. __`function`__ Bultins (```types.Builtin```) are modified with `defaultLibrary`
(e.g., ```make```, ```len```, ```copy```). Identifiers whose
object is ```types.Func``` or whose node is ```ast.FuncDecl``` are `function`.
1. __`comment`__ Comments and struct tags. (Perhaps struct tags should be `property`?)
1. __`string`__ Strings. Could add modifiers for e.g., escapes or format codes.
1. __`number`__ Numbers. Should the ```i``` in ```23i``` be handled specially?
1. __`operator`__ Assignment operators, binary operators, ellipses (```...```), increment/decrement
operators, sends (```<-```), and unary operators.

Gopls will send the modifier `deprecated` if it finds a comment
```// deprecated``` in the godoc.

The unused tokens for Go code are `class`, `enum`, `interface`,
		`struct`, `typeParameter`, `property`, `enumMember`,
		`event`, `macro`, `modifier`,
		`regexp`

## Colors

These comments are about vscode.

The documentation has a [helpful](https://code.visualstudio.com/api/language-extensions/semantic-highlight-guide#custom-textmate-scope-mappings)
description of which semantic tokens correspond to scopes in TextMate grammars. Themes seem
to use the TextMate scopes to decide on colors.

Some examples of color customizations are [here](https://medium.com/@danromans/how-to-customize-semantic-token-colorization-with-visual-studio-code-ac3eab96141b).

## Note

While a file is being edited it may temporarily contain either
parsing errors or type errors. In this case gopls cannot determine some (or maybe any)
of the semantic tokens. To avoid weird flickering it is the responsibility
of clients to maintain the semantic token information
in the unedited part of the file, and they do.


================================================
FILE: gopls/internal/protocol/semtok/semtok.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The semtok package provides an encoder for LSP's semantic tokens.
package semtok

import "sort"

// A Token provides the extent and semantics of a token.
type Token struct {
	Line, Start uint32 // 0-based UTF-16 index
	Len         uint32 // in UTF-16 codes
	Type        Type
	Modifiers   []Modifier
}

type Type string

const (
	// These are the tokens defined by LSP 3.18, but a client is
	// free to send its own set; any tokens that the server emits
	// that are not in this set are simply not encoded in the bitfield.
	TokComment   Type = "comment"       // for a comment
	TokFunction  Type = "function"      // for a function
	TokKeyword   Type = "keyword"       // for a keyword
	TokLabel     Type = "label"         // for a control label (LSP 3.18)
	TokMacro     Type = "macro"         // for text/template tokens
	TokMethod    Type = "method"        // for a method
	TokNamespace Type = "namespace"     // for an imported package name
	TokNumber    Type = "number"        // for a numeric literal
	TokOperator  Type = "operator"      // for an operator
	TokParameter Type = "parameter"     // for a parameter variable
	TokProperty  Type = "property"      // for a struct field
	TokString    Type = "string"        // for a string literal
	TokType      Type = "type"          // for a type name (plus other uses)
	TokTypeParam Type = "typeParameter" // for a type parameter
	TokVariable  Type = "variable"      // for a var or const
	// The section below defines a subset of token types in standard token types
	// that gopls does not use.
	//
	// If you move types to above, document it in
	// gopls/doc/features/passive.md#semantic-tokens.
	// TokClass      Type = "class"
	// TokDecorator  Type = "decorator"
	// TokEnum       Type = "enum"
	// TokEnumMember Type = "enumMember"
	// TokEvent      Type = "event"
	// TokInterface  Type = "interface"
	// TokModifier   Type = "modifier"
	// TokRegexp     Type = "regexp"
	// TokStruct     Type = "struct"
)

// Types is a slice of types gopls will return as its server capabilities.
var Types = []Type{
	TokNamespace,
	TokType,
	TokTypeParam,
	TokParameter,
	TokProperty,
	TokVariable,
	TokFunction,
	TokMethod,
	TokMacro,
	TokKeyword,
	TokComment,
	TokString,
	TokNumber,
	TokOperator,
	TokLabel,
}

type Modifier string

const (
	// LSP 3.18 standard modifiers
	// As with Types, clients get only the modifiers they request.
	//
	// The section below defines a subset of modifiers in standard modifiers
	// that gopls understand.
	ModDefaultLibrary Modifier = "defaultLibrary" // for predeclared symbols
	ModDefinition     Modifier = "definition"     // for the declaring identifier of a symbol
	ModReadonly       Modifier = "readonly"       // for constants (TokVariable)
	ModStatic         Modifier = "static"         // for package-level variables
	// The section below defines the rest of the modifiers in standard modifiers
	// that gopls does not use.
	//
	// If you move modifiers to above, document it in
	// gopls/doc/features/passive.md#semantic-tokens.
	// ModAbstract      Modifier = "abstract"
	// ModAsync         Modifier = "async"
	// ModDeclaration   Modifier = "declaration"
	// ModDeprecated    Modifier = "deprecated"
	// ModDocumentation Modifier = "documentation"
	// ModModification  Modifier = "modification"

	// non-standard modifiers
	//
	// Since the type of a symbol is orthogonal to its kind,
	// (e.g. a variable can have function type),
	// we use modifiers for the top-level type constructor.
	ModArray     Modifier = "array"
	ModBool      Modifier = "bool"
	ModChan      Modifier = "chan"
	ModFormat    Modifier = "format" // for format string directives such as "%s"
	ModInterface Modifier = "interface"
	ModMap       Modifier = "map"
	ModNumber    Modifier = "number"
	ModPointer   Modifier = "pointer"
	ModSignature Modifier = "signature" // for function types
	ModSlice     Modifier = "slice"
	ModString    Modifier = "string"
	ModStruct    Modifier = "struct"
)

// Modifiers is a slice of modifiers gopls will return as its server capabilities.
var Modifiers = []Modifier{
	// LSP 3.18 standard modifiers.
	ModDefinition,
	ModReadonly,
	ModDefaultLibrary,
	ModStatic,
	// Additional custom modifiers.
	ModArray,
	ModBool,
	ModChan,
	ModFormat,
	ModInterface,
	ModMap,
	ModNumber,
	ModPointer,
	ModSignature,
	ModSlice,
	ModString,
	ModStruct,
}

// Encode returns the LSP encoding of a sequence of tokens.
// encodeType and encodeModifier maps control which types and modifiers are
// excluded in the response. If a type or modifier maps to false, it will be
// omitted from the output.
func Encode(
	tokens []Token,
	encodeType map[Type]bool,
	encodeModifier map[Modifier]bool) []uint32 {

	// binary operators, at least, will be out of order
	sort.Slice(tokens, func(i, j int) bool {
		if tokens[i].Line != tokens[j].Line {
			return tokens[i].Line < tokens[j].Line
		}
		return tokens[i].Start < tokens[j].Start
	})

	typeMap := make(map[Type]int)
	for i, t := range Types {
		if enable, ok := encodeType[t]; ok && !enable {
			continue
		}
		typeMap[Type(t)] = i
	}

	modMap := make(map[Modifier]int)
	for i, m := range Modifiers {
		if enable, ok := encodeModifier[m]; ok && !enable {
			continue
		}
		modMap[Modifier(m)] = 1 << i
	}

	// each semantic token needs five values but some tokens might be skipped.
	// (see Integer Encoding for Tokens in the LSP spec)
	x := make([]uint32, 5*len(tokens))
	var j int
	var last Token
	for i := range tokens {
		item := tokens[i]
		typ, ok := typeMap[item.Type]
		if !ok {
			continue // client doesn't want semantic token info.
		}
		if j == 0 {
			x[0] = tokens[0].Line
		} else {
			x[j] = item.Line - last.Line
		}
		x[j+1] = item.Start
		if j > 0 && x[j] == 0 {
			x[j+1] = item.Start - last.Start
		}
		x[j+2] = item.Len
		x[j+3] = uint32(typ)
		mask := 0
		for _, s := range item.Modifiers {
			// modMap[s] is 0 if the client doesn't want this modifier
			mask |= modMap[s]
		}
		x[j+4] = uint32(mask)
		j += 5
		last = item
	}
	return x[:j]
}


================================================
FILE: gopls/internal/protocol/span.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"fmt"
	"unicode/utf8"
)

// Empty reports whether the Range is an empty selection.
func (rng Range) Empty() bool { return rng.Start == rng.End }

// Contains reports whether the position is within the range, inclusive of the
// start and end positions.
func (rng Range) Contains(pos Position) bool {
	return ComparePosition(rng.Start, pos) <= 0 &&
		ComparePosition(pos, rng.End) <= 0
}

// Empty reports whether the Location is an empty selection.
func (loc Location) Empty() bool { return loc.Range.Empty() }

// CompareLocation defines a three-valued comparison over locations,
// lexicographically ordered by (URI, Range).
func CompareLocation(x, y Location) int {
	if x.URI != y.URI {
		if x.URI < y.URI {
			return -1
		} else {
			return +1
		}
	}
	return CompareRange(x.Range, y.Range)
}

// CompareRange returns -1 if a is before b, 0 if a == b, and 1 if a is after b.
//
// A range a is defined to be 'before' b if a.Start is before b.Start, or
// a.Start == b.Start and a.End is before b.End.
func CompareRange(a, b Range) int {
	if r := ComparePosition(a.Start, b.Start); r != 0 {
		return r
	}
	return ComparePosition(a.End, b.End)
}

// ComparePosition returns -1 if a is before b, 0 if a == b, and 1 if a is after b.
func ComparePosition(a, b Position) int {
	if a.Line != b.Line {
		if a.Line < b.Line {
			return -1
		} else {
			return +1
		}
	}
	if a.Character != b.Character {
		if a.Character < b.Character {
			return -1
		} else {
			return +1
		}
	}
	return 0
}

// Intersect reports whether x and y intersect.
//
// Two non-empty half-open integer intervals intersect iff:
//
//	y.start < x.end && x.start < y.end
//
// Mathematical conventional views an interval as a set of integers.
// An empty interval is the empty set, so its intersection with any
// other interval is empty, and thus an empty interval does not
// intersect any other interval.
//
// However, this function uses a looser definition appropriate for
// text selections: if either x or y is empty, it uses <= operators
// instead, so an empty range within or abutting a non-empty range is
// considered to overlap it, and an empty range overlaps itself.
//
// This handles the common case in which there is no selection, but
// the cursor is at the start or end of an expression and the caller
// wants to know whether the cursor intersects the range of the
// expression. The answer in this case should be yes, even though the
// selection is empty. Similarly the answer should also be yes if the
// cursor is properly within the range of the expression. But a
// non-empty selection abutting the expression should not be
// considered to intersect it.
func Intersect(x, y Range) bool {
	r1 := ComparePosition(x.Start, y.End)
	r2 := ComparePosition(y.Start, x.End)
	if r1 < 0 && r2 < 0 {
		return true // mathematical intersection
	}
	return (x.Empty() || y.Empty()) && r1 <= 0 && r2 <= 0
}

// Format implements fmt.Formatter.
//
// Note: Formatter is implemented instead of Stringer (presumably) for
// performance reasons, though it is not clear that it matters in practice.
func (r Range) Format(f fmt.State, _ rune) {
	fmt.Fprintf(f, "%v-%v", r.Start, r.End)
}

// Format implements fmt.Formatter.
//
// See Range.Format for discussion of why the Formatter interface is
// implemented rather than Stringer.
func (p Position) Format(f fmt.State, _ rune) {
	fmt.Fprintf(f, "%v:%v", p.Line, p.Character)
}

// -- implementation helpers --

// UTF16Len returns the number of codes in the UTF-16 transcoding of s.
func UTF16Len(s []byte) int {
	var n int
	for len(s) > 0 {
		n++

		// Fast path for ASCII.
		if s[0] < 0x80 {
			s = s[1:]
			continue
		}

		r, size := utf8.DecodeRune(s)
		if r >= 0x10000 {
			n++ // surrogate pair
		}
		s = s[size:]
	}
	return n
}


================================================
FILE: gopls/internal/protocol/tsclient.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated for LSP. DO NOT EDIT.

package protocol

// Code generated from protocol/metaModel.json at ref release/protocol/3.17.6-next.14 (hash 66a087310eea0d60495ba3578d78f70409c403d9).
// https://github.com/microsoft/vscode-languageserver-node/blob/release/protocol/3.17.6-next.14/protocol/metaModel.json
// LSP metaData.version = 3.17.0.

import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/internal/jsonrpc2"
)

type Client interface {
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#logTrace
	LogTrace(context.Context, *LogTraceParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#progress
	Progress(context.Context, *ProgressParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#client_registerCapability
	RegisterCapability(context.Context, *RegistrationParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#client_unregisterCapability
	UnregisterCapability(context.Context, *UnregistrationParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#telemetry_event
	Event(context.Context, *any) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_publishDiagnostics
	PublishDiagnostics(context.Context, *PublishDiagnosticsParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_logMessage
	LogMessage(context.Context, *LogMessageParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_showDocument
	ShowDocument(context.Context, *ShowDocumentParams) (*ShowDocumentResult, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_showMessage
	ShowMessage(context.Context, *ShowMessageParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_showMessageRequest
	ShowMessageRequest(context.Context, *ShowMessageRequestParams) (*MessageActionItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_workDoneProgress_create
	WorkDoneProgressCreate(context.Context, *WorkDoneProgressCreateParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_applyEdit
	ApplyEdit(context.Context, *ApplyWorkspaceEditParams) (*ApplyWorkspaceEditResult, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_codeLens_refresh
	CodeLensRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_configuration
	Configuration(context.Context, *ParamConfiguration) ([]LSPAny, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_diagnostic_refresh
	DiagnosticRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_foldingRange_refresh
	FoldingRangeRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_inlayHint_refresh
	InlayHintRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_inlineValue_refresh
	InlineValueRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_semanticTokens_refresh
	SemanticTokensRefresh(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_textDocumentContent_refresh
	TextDocumentContentRefresh(context.Context, *TextDocumentContentRefreshParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_workspaceFolders
	WorkspaceFolders(context.Context) ([]WorkspaceFolder, error)
}

func clientDispatch(ctx context.Context, client Client, reply jsonrpc2.Replier, r jsonrpc2.Request) (bool, error) {
	resp, valid, err := ClientDispatchCall(ctx, client, r.Method(), r.Params())
	if !valid {
		return false, nil
	}

	if err != nil {
		return valid, reply(ctx, nil, err)
	} else {
		return valid, reply(ctx, resp, nil)
	}
}

func ClientDispatchCall(ctx context.Context, client Client, method string, raw json.RawMessage) (resp any, _ bool, err error) {
	switch method {
	case "$/logTrace":
		var params LogTraceParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.LogTrace(ctx, &params)
		return nil, true, err

	case "$/progress":
		var params ProgressParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.Progress(ctx, &params)
		return nil, true, err

	case "client/registerCapability":
		var params RegistrationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.RegisterCapability(ctx, &params)
		return nil, true, err

	case "client/unregisterCapability":
		var params UnregistrationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.UnregisterCapability(ctx, &params)
		return nil, true, err

	case "telemetry/event":
		var params any
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.Event(ctx, &params)
		return nil, true, err

	case "textDocument/publishDiagnostics":
		var params PublishDiagnosticsParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.PublishDiagnostics(ctx, &params)
		return nil, true, err

	case "window/logMessage":
		var params LogMessageParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.LogMessage(ctx, &params)
		return nil, true, err

	case "window/showDocument":
		var params ShowDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := client.ShowDocument(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "window/showMessage":
		var params ShowMessageParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.ShowMessage(ctx, &params)
		return nil, true, err

	case "window/showMessageRequest":
		var params ShowMessageRequestParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := client.ShowMessageRequest(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "window/workDoneProgress/create":
		var params WorkDoneProgressCreateParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.WorkDoneProgressCreate(ctx, &params)
		return nil, true, err

	case "workspace/applyEdit":
		var params ApplyWorkspaceEditParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := client.ApplyEdit(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/codeLens/refresh":
		err := client.CodeLensRefresh(ctx)
		return nil, true, err

	case "workspace/configuration":
		var params ParamConfiguration
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := client.Configuration(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/diagnostic/refresh":
		err := client.DiagnosticRefresh(ctx)
		return nil, true, err

	case "workspace/foldingRange/refresh":
		err := client.FoldingRangeRefresh(ctx)
		return nil, true, err

	case "workspace/inlayHint/refresh":
		err := client.InlayHintRefresh(ctx)
		return nil, true, err

	case "workspace/inlineValue/refresh":
		err := client.InlineValueRefresh(ctx)
		return nil, true, err

	case "workspace/semanticTokens/refresh":
		err := client.SemanticTokensRefresh(ctx)
		return nil, true, err

	case "workspace/textDocumentContent/refresh":
		var params TextDocumentContentRefreshParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := client.TextDocumentContentRefresh(ctx, &params)
		return nil, true, err

	case "workspace/workspaceFolders":
		resp, err := client.WorkspaceFolders(ctx)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	default:
		return nil, false, nil
	}
}

func (s *clientDispatcher) LogTrace(ctx context.Context, params *LogTraceParams) error {
	return s.sender.Notify(ctx, "$/logTrace", params)
}
func (s *clientDispatcher) Progress(ctx context.Context, params *ProgressParams) error {
	return s.sender.Notify(ctx, "$/progress", params)
}
func (s *clientDispatcher) RegisterCapability(ctx context.Context, params *RegistrationParams) error {
	return s.sender.Call(ctx, "client/registerCapability", params, nil)
}
func (s *clientDispatcher) UnregisterCapability(ctx context.Context, params *UnregistrationParams) error {
	return s.sender.Call(ctx, "client/unregisterCapability", params, nil)
}
func (s *clientDispatcher) Event(ctx context.Context, params *any) error {
	return s.sender.Notify(ctx, "telemetry/event", params)
}
func (s *clientDispatcher) PublishDiagnostics(ctx context.Context, params *PublishDiagnosticsParams) error {
	return s.sender.Notify(ctx, "textDocument/publishDiagnostics", params)
}
func (s *clientDispatcher) LogMessage(ctx context.Context, params *LogMessageParams) error {
	return s.sender.Notify(ctx, "window/logMessage", params)
}
func (s *clientDispatcher) ShowDocument(ctx context.Context, params *ShowDocumentParams) (*ShowDocumentResult, error) {
	var result *ShowDocumentResult
	if err := s.sender.Call(ctx, "window/showDocument", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *clientDispatcher) ShowMessage(ctx context.Context, params *ShowMessageParams) error {
	return s.sender.Notify(ctx, "window/showMessage", params)
}
func (s *clientDispatcher) ShowMessageRequest(ctx context.Context, params *ShowMessageRequestParams) (*MessageActionItem, error) {
	var result *MessageActionItem
	if err := s.sender.Call(ctx, "window/showMessageRequest", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *clientDispatcher) WorkDoneProgressCreate(ctx context.Context, params *WorkDoneProgressCreateParams) error {
	return s.sender.Call(ctx, "window/workDoneProgress/create", params, nil)
}
func (s *clientDispatcher) ApplyEdit(ctx context.Context, params *ApplyWorkspaceEditParams) (*ApplyWorkspaceEditResult, error) {
	var result *ApplyWorkspaceEditResult
	if err := s.sender.Call(ctx, "workspace/applyEdit", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *clientDispatcher) CodeLensRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/codeLens/refresh", nil, nil)
}
func (s *clientDispatcher) Configuration(ctx context.Context, params *ParamConfiguration) ([]LSPAny, error) {
	var result []LSPAny
	if err := s.sender.Call(ctx, "workspace/configuration", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *clientDispatcher) DiagnosticRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/diagnostic/refresh", nil, nil)
}
func (s *clientDispatcher) FoldingRangeRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/foldingRange/refresh", nil, nil)
}
func (s *clientDispatcher) InlayHintRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/inlayHint/refresh", nil, nil)
}
func (s *clientDispatcher) InlineValueRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/inlineValue/refresh", nil, nil)
}
func (s *clientDispatcher) SemanticTokensRefresh(ctx context.Context) error {
	return s.sender.Call(ctx, "workspace/semanticTokens/refresh", nil, nil)
}
func (s *clientDispatcher) TextDocumentContentRefresh(ctx context.Context, params *TextDocumentContentRefreshParams) error {
	return s.sender.Call(ctx, "workspace/textDocumentContent/refresh", params, nil)
}
func (s *clientDispatcher) WorkspaceFolders(ctx context.Context) ([]WorkspaceFolder, error) {
	var result []WorkspaceFolder
	if err := s.sender.Call(ctx, "workspace/workspaceFolders", nil, &result); err != nil {
		return nil, err
	}
	return result, nil
}


================================================
FILE: gopls/internal/protocol/tsdocument_changes.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"encoding/json"
	"fmt"
)

// DocumentChange is a union of various file edit operations.
//
// Exactly one field of this struct is non-nil; see [DocumentChange.Valid].
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#resourceChanges
type DocumentChange struct {
	TextDocumentEdit *TextDocumentEdit
	CreateFile       *CreateFile
	RenameFile       *RenameFile
	DeleteFile       *DeleteFile
}

// Valid reports whether the DocumentChange sum-type value is valid,
// that is, exactly one of create, delete, edit, or rename.
func (ch DocumentChange) Valid() bool {
	n := 0
	if ch.TextDocumentEdit != nil {
		n++
	}
	if ch.CreateFile != nil {
		n++
	}
	if ch.RenameFile != nil {
		n++
	}
	if ch.DeleteFile != nil {
		n++
	}
	return n == 1
}

func (d *DocumentChange) UnmarshalJSON(data []byte) error {
	var m map[string]any
	if err := json.Unmarshal(data, &m); err != nil {
		return err
	}

	if _, ok := m["textDocument"]; ok {
		d.TextDocumentEdit = new(TextDocumentEdit)
		return json.Unmarshal(data, d.TextDocumentEdit)
	}

	// The {Create,Rename,Delete}File types all share a 'kind' field.
	kind := m["kind"]
	switch kind {
	case "create":
		d.CreateFile = new(CreateFile)
		return json.Unmarshal(data, d.CreateFile)
	case "rename":
		d.RenameFile = new(RenameFile)
		return json.Unmarshal(data, d.RenameFile)
	case "delete":
		d.DeleteFile = new(DeleteFile)
		return json.Unmarshal(data, d.DeleteFile)
	}
	return fmt.Errorf("DocumentChanges: unexpected kind: %q", kind)
}

func (d *DocumentChange) MarshalJSON() ([]byte, error) {
	if d.TextDocumentEdit != nil {
		return json.Marshal(d.TextDocumentEdit)
	} else if d.CreateFile != nil {
		return json.Marshal(d.CreateFile)
	} else if d.RenameFile != nil {
		return json.Marshal(d.RenameFile)
	} else if d.DeleteFile != nil {
		return json.Marshal(d.DeleteFile)
	}
	return nil, fmt.Errorf("empty DocumentChanges union value")
}


================================================
FILE: gopls/internal/protocol/tsinsertreplaceedit.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"encoding/json"
	"fmt"
)

// InsertReplaceEdit is used instead of TextEdit in CompletionItem
// in editors that support it. These two types are alike in appearance
// but can be differentiated by the presence or absence of
// certain properties. UnmarshalJSON of the sum type tries to
// unmarshal as TextEdit only if unmarshal as InsertReplaceEdit fails.
// However, due to this similarity, unmarshal with the other type
// never fails. This file has a custom JSON unmarshaller for
// InsertReplaceEdit, that fails if the required fields are missing.

// UnmarshalJSON unmarshals InsertReplaceEdit with extra
// checks on the presence of "insert" and "replace" properties.
func (e *InsertReplaceEdit) UnmarshalJSON(data []byte) error {
	var required struct {
		NewText string
		Insert  *Range `json:"insert,omitempty"`
		Replace *Range `json:"replace,omitempty"`
	}

	if err := json.Unmarshal(data, &required); err != nil {
		return err
	}
	if required.Insert == nil && required.Replace == nil {
		return fmt.Errorf("not InsertReplaceEdit")
	}
	e.NewText = required.NewText
	e.Insert = *required.Insert
	e.Replace = *required.Replace
	return nil
}


================================================
FILE: gopls/internal/protocol/tsinsertreplaceedit_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

import (
	"encoding/json"
	"testing"

	"github.com/google/go-cmp/cmp"
)

func TestInsertReplaceEdit_UnmarshalJSON(t *testing.T) {
	tests := []struct {
		name    string
		in      any
		wantErr bool
	}{
		{
			name: "TextEdit",
			in:   TextEdit{NewText: "new text", Range: Range{Start: Position{Line: 1}}},
		},
		{
			name: "InsertReplaceEdit",
			in:   InsertReplaceEdit{NewText: "new text", Insert: Range{Start: Position{Line: 100}}, Replace: Range{End: Position{Line: 200}}},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			data, err := json.MarshalIndent(Or_CompletionItem_textEdit{Value: tt.in}, "", " ")
			if err != nil {
				t.Fatalf("failed to marshal: %v", err)
			}
			var decoded Or_CompletionItem_textEdit
			if err := json.Unmarshal(data, &decoded); err != nil {
				t.Fatalf("failed to unmarshal: %v", err)
			}
			if diff := cmp.Diff(tt.in, decoded.Value); diff != "" {
				t.Errorf("unmarshal returns unexpected result: (-want +got):\n%s", diff)
			}
		})
	}
}


================================================
FILE: gopls/internal/protocol/tsjson.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated for LSP. DO NOT EDIT.

package protocol

// Code generated from protocol/metaModel.json at ref release/protocol/3.17.6-next.14 (hash 66a087310eea0d60495ba3578d78f70409c403d9).
// https://github.com/microsoft/vscode-languageserver-node/blob/release/protocol/3.17.6-next.14/protocol/metaModel.json
// LSP metaData.version = 3.17.0.

import "encoding/json"

import "fmt"

// UnmarshalError indicates that a JSON value did not conform to
// one of the expected cases of an LSP union type.
type UnmarshalError struct {
	msg string
}

func (e UnmarshalError) Error() string {
	return e.msg
}
func (t OrPLocation_workspace_symbol) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case Location:
		return json.Marshal(x)
	case LocationUriOnly:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [Location LocationUriOnly]", t)
}

func (t *OrPLocation_workspace_symbol) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 Location
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 LocationUriOnly
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [Location LocationUriOnly]"}
}

func (t OrPSection_workspace_didChangeConfiguration) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case []string:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [[]string string]", t)
}

func (t *OrPSection_workspace_didChangeConfiguration) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 []string
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [[]string string]"}
}

func (t OrPTooltipPLabel) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkupContent:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkupContent string]", t)
}

func (t *OrPTooltipPLabel) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkupContent
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkupContent string]"}
}

func (t OrPTooltip_textDocument_inlayHint) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkupContent:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkupContent string]", t)
}

func (t *OrPTooltip_textDocument_inlayHint) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkupContent
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkupContent string]"}
}

func (t Or_CancelParams_id) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case int32:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [int32 string]", t)
}

func (t *Or_CancelParams_id) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 int32
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [int32 string]"}
}

func (t Or_ClientSemanticTokensRequestOptions_full) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case ClientSemanticTokensRequestFullDelta:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [ClientSemanticTokensRequestFullDelta bool]", t)
}

func (t *Or_ClientSemanticTokensRequestOptions_full) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 ClientSemanticTokensRequestFullDelta
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [ClientSemanticTokensRequestFullDelta bool]"}
}

func (t Or_ClientSemanticTokensRequestOptions_range) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case Lit_ClientSemanticTokensRequestOptions_range_Item1:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [Lit_ClientSemanticTokensRequestOptions_range_Item1 bool]", t)
}

func (t *Or_ClientSemanticTokensRequestOptions_range) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 Lit_ClientSemanticTokensRequestOptions_range_Item1
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [Lit_ClientSemanticTokensRequestOptions_range_Item1 bool]"}
}

func (t Or_CompletionItemDefaults_editRange) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case EditRangeWithInsertReplace:
		return json.Marshal(x)
	case Range:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [EditRangeWithInsertReplace Range]", t)
}

func (t *Or_CompletionItemDefaults_editRange) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 EditRangeWithInsertReplace
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 Range
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [EditRangeWithInsertReplace Range]"}
}

func (t Or_CompletionItem_documentation) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkupContent:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkupContent string]", t)
}

func (t *Or_CompletionItem_documentation) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkupContent
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkupContent string]"}
}

func (t Or_CompletionItem_textEdit) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InsertReplaceEdit:
		return json.Marshal(x)
	case TextEdit:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InsertReplaceEdit TextEdit]", t)
}

func (t *Or_CompletionItem_textEdit) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InsertReplaceEdit
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TextEdit
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InsertReplaceEdit TextEdit]"}
}

func (t Or_Definition) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case Location:
		return json.Marshal(x)
	case []Location:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [Location []Location]", t)
}

func (t *Or_Definition) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 Location
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 []Location
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [Location []Location]"}
}

func (t Or_Diagnostic_code) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case int32:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [int32 string]", t)
}

func (t *Or_Diagnostic_code) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 int32
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [int32 string]"}
}

func (t Or_DocumentDiagnosticReport) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case RelatedFullDocumentDiagnosticReport:
		return json.Marshal(x)
	case RelatedUnchangedDocumentDiagnosticReport:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [RelatedFullDocumentDiagnosticReport RelatedUnchangedDocumentDiagnosticReport]", t)
}

func (t *Or_DocumentDiagnosticReport) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 RelatedFullDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 RelatedUnchangedDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [RelatedFullDocumentDiagnosticReport RelatedUnchangedDocumentDiagnosticReport]"}
}

func (t Or_DocumentDiagnosticReportPartialResult_relatedDocuments_Value) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case FullDocumentDiagnosticReport:
		return json.Marshal(x)
	case UnchangedDocumentDiagnosticReport:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]", t)
}

func (t *Or_DocumentDiagnosticReportPartialResult_relatedDocuments_Value) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 FullDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 UnchangedDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]"}
}

func (t Or_DocumentFilter) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookCellTextDocumentFilter:
		return json.Marshal(x)
	case TextDocumentFilter:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookCellTextDocumentFilter TextDocumentFilter]", t)
}

func (t *Or_DocumentFilter) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookCellTextDocumentFilter
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TextDocumentFilter
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookCellTextDocumentFilter TextDocumentFilter]"}
}

func (t Or_GlobPattern) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case Pattern:
		return json.Marshal(x)
	case RelativePattern:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [Pattern RelativePattern]", t)
}

func (t *Or_GlobPattern) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 Pattern
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 RelativePattern
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [Pattern RelativePattern]"}
}

func (t Or_Hover_contents) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkedString:
		return json.Marshal(x)
	case MarkupContent:
		return json.Marshal(x)
	case []MarkedString:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkedString MarkupContent []MarkedString]", t)
}

func (t *Or_Hover_contents) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkedString
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 MarkupContent
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 []MarkedString
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkedString MarkupContent []MarkedString]"}
}

func (t Or_InlayHint_label) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case []InlayHintLabelPart:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [[]InlayHintLabelPart string]", t)
}

func (t *Or_InlayHint_label) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 []InlayHintLabelPart
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [[]InlayHintLabelPart string]"}
}

func (t Or_InlineCompletionItem_insertText) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case StringValue:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [StringValue string]", t)
}

func (t *Or_InlineCompletionItem_insertText) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 StringValue
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [StringValue string]"}
}

func (t Or_InlineValue) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InlineValueEvaluatableExpression:
		return json.Marshal(x)
	case InlineValueText:
		return json.Marshal(x)
	case InlineValueVariableLookup:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InlineValueEvaluatableExpression InlineValueText InlineValueVariableLookup]", t)
}

func (t *Or_InlineValue) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InlineValueEvaluatableExpression
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 InlineValueText
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 InlineValueVariableLookup
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InlineValueEvaluatableExpression InlineValueText InlineValueVariableLookup]"}
}

func (t Or_MarkedString) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkedStringWithLanguage:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkedStringWithLanguage string]", t)
}

func (t *Or_MarkedString) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkedStringWithLanguage
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkedStringWithLanguage string]"}
}

func (t Or_NotebookCellTextDocumentFilter_notebook) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentFilter:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentFilter string]", t)
}

func (t *Or_NotebookCellTextDocumentFilter_notebook) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentFilter
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentFilter string]"}
}

func (t Or_NotebookDocumentFilter) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentFilterNotebookType:
		return json.Marshal(x)
	case NotebookDocumentFilterPattern:
		return json.Marshal(x)
	case NotebookDocumentFilterScheme:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentFilterNotebookType NotebookDocumentFilterPattern NotebookDocumentFilterScheme]", t)
}

func (t *Or_NotebookDocumentFilter) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentFilterNotebookType
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 NotebookDocumentFilterPattern
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 NotebookDocumentFilterScheme
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentFilterNotebookType NotebookDocumentFilterPattern NotebookDocumentFilterScheme]"}
}

func (t Or_NotebookDocumentFilterWithCells_notebook) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentFilter:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentFilter string]", t)
}

func (t *Or_NotebookDocumentFilterWithCells_notebook) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentFilter
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentFilter string]"}
}

func (t Or_NotebookDocumentFilterWithNotebook_notebook) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentFilter:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentFilter string]", t)
}

func (t *Or_NotebookDocumentFilterWithNotebook_notebook) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentFilter
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentFilter string]"}
}

func (t Or_NotebookDocumentSyncOptions_notebookSelector_Elem) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentFilterWithCells:
		return json.Marshal(x)
	case NotebookDocumentFilterWithNotebook:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentFilterWithCells NotebookDocumentFilterWithNotebook]", t)
}

func (t *Or_NotebookDocumentSyncOptions_notebookSelector_Elem) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentFilterWithCells
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 NotebookDocumentFilterWithNotebook
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentFilterWithCells NotebookDocumentFilterWithNotebook]"}
}

func (t Or_RelatedFullDocumentDiagnosticReport_relatedDocuments_Value) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case FullDocumentDiagnosticReport:
		return json.Marshal(x)
	case UnchangedDocumentDiagnosticReport:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]", t)
}

func (t *Or_RelatedFullDocumentDiagnosticReport_relatedDocuments_Value) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 FullDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 UnchangedDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]"}
}

func (t Or_RelatedUnchangedDocumentDiagnosticReport_relatedDocuments_Value) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case FullDocumentDiagnosticReport:
		return json.Marshal(x)
	case UnchangedDocumentDiagnosticReport:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]", t)
}

func (t *Or_RelatedUnchangedDocumentDiagnosticReport_relatedDocuments_Value) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 FullDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 UnchangedDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]"}
}

func (t Or_Result_textDocument_codeAction_Item0_Elem) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case CodeAction:
		return json.Marshal(x)
	case Command:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [CodeAction Command]", t)
}

func (t *Or_Result_textDocument_codeAction_Item0_Elem) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 CodeAction
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 Command
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [CodeAction Command]"}
}

func (t Or_Result_textDocument_inlineCompletion) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InlineCompletionList:
		return json.Marshal(x)
	case []InlineCompletionItem:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InlineCompletionList []InlineCompletionItem]", t)
}

func (t *Or_Result_textDocument_inlineCompletion) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InlineCompletionList
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 []InlineCompletionItem
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InlineCompletionList []InlineCompletionItem]"}
}

func (t Or_SemanticTokensOptions_full) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case SemanticTokensFullDelta:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [SemanticTokensFullDelta bool]", t)
}

func (t *Or_SemanticTokensOptions_full) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 SemanticTokensFullDelta
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [SemanticTokensFullDelta bool]"}
}

func (t Or_SemanticTokensOptions_range) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case PRangeESemanticTokensOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [PRangeESemanticTokensOptions bool]", t)
}

func (t *Or_SemanticTokensOptions_range) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 PRangeESemanticTokensOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [PRangeESemanticTokensOptions bool]"}
}

func (t Or_ServerCapabilities_callHierarchyProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case CallHierarchyOptions:
		return json.Marshal(x)
	case CallHierarchyRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [CallHierarchyOptions CallHierarchyRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_callHierarchyProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 CallHierarchyOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 CallHierarchyRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [CallHierarchyOptions CallHierarchyRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_codeActionProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case CodeActionOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [CodeActionOptions bool]", t)
}

func (t *Or_ServerCapabilities_codeActionProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 CodeActionOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [CodeActionOptions bool]"}
}

func (t Or_ServerCapabilities_colorProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DocumentColorOptions:
		return json.Marshal(x)
	case DocumentColorRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DocumentColorOptions DocumentColorRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_colorProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DocumentColorOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 DocumentColorRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DocumentColorOptions DocumentColorRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_declarationProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DeclarationOptions:
		return json.Marshal(x)
	case DeclarationRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DeclarationOptions DeclarationRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_declarationProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DeclarationOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 DeclarationRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DeclarationOptions DeclarationRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_definitionProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DefinitionOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DefinitionOptions bool]", t)
}

func (t *Or_ServerCapabilities_definitionProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DefinitionOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DefinitionOptions bool]"}
}

func (t Or_ServerCapabilities_diagnosticProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DiagnosticOptions:
		return json.Marshal(x)
	case DiagnosticRegistrationOptions:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DiagnosticOptions DiagnosticRegistrationOptions]", t)
}

func (t *Or_ServerCapabilities_diagnosticProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DiagnosticOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 DiagnosticRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DiagnosticOptions DiagnosticRegistrationOptions]"}
}

func (t Or_ServerCapabilities_documentFormattingProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DocumentFormattingOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DocumentFormattingOptions bool]", t)
}

func (t *Or_ServerCapabilities_documentFormattingProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DocumentFormattingOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DocumentFormattingOptions bool]"}
}

func (t Or_ServerCapabilities_documentHighlightProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DocumentHighlightOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DocumentHighlightOptions bool]", t)
}

func (t *Or_ServerCapabilities_documentHighlightProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DocumentHighlightOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DocumentHighlightOptions bool]"}
}

func (t Or_ServerCapabilities_documentRangeFormattingProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DocumentRangeFormattingOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DocumentRangeFormattingOptions bool]", t)
}

func (t *Or_ServerCapabilities_documentRangeFormattingProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DocumentRangeFormattingOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DocumentRangeFormattingOptions bool]"}
}

func (t Or_ServerCapabilities_documentSymbolProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case DocumentSymbolOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [DocumentSymbolOptions bool]", t)
}

func (t *Or_ServerCapabilities_documentSymbolProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 DocumentSymbolOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [DocumentSymbolOptions bool]"}
}

func (t Or_ServerCapabilities_foldingRangeProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case FoldingRangeOptions:
		return json.Marshal(x)
	case FoldingRangeRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [FoldingRangeOptions FoldingRangeRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_foldingRangeProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 FoldingRangeOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 FoldingRangeRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [FoldingRangeOptions FoldingRangeRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_hoverProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case HoverOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [HoverOptions bool]", t)
}

func (t *Or_ServerCapabilities_hoverProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 HoverOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [HoverOptions bool]"}
}

func (t Or_ServerCapabilities_implementationProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case ImplementationOptions:
		return json.Marshal(x)
	case ImplementationRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [ImplementationOptions ImplementationRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_implementationProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 ImplementationOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 ImplementationRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [ImplementationOptions ImplementationRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_inlayHintProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InlayHintOptions:
		return json.Marshal(x)
	case InlayHintRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InlayHintOptions InlayHintRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_inlayHintProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InlayHintOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 InlayHintRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InlayHintOptions InlayHintRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_inlineCompletionProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InlineCompletionOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InlineCompletionOptions bool]", t)
}

func (t *Or_ServerCapabilities_inlineCompletionProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InlineCompletionOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InlineCompletionOptions bool]"}
}

func (t Or_ServerCapabilities_inlineValueProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case InlineValueOptions:
		return json.Marshal(x)
	case InlineValueRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [InlineValueOptions InlineValueRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_inlineValueProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 InlineValueOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 InlineValueRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [InlineValueOptions InlineValueRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_linkedEditingRangeProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case LinkedEditingRangeOptions:
		return json.Marshal(x)
	case LinkedEditingRangeRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [LinkedEditingRangeOptions LinkedEditingRangeRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_linkedEditingRangeProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 LinkedEditingRangeOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 LinkedEditingRangeRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [LinkedEditingRangeOptions LinkedEditingRangeRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_monikerProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MonikerOptions:
		return json.Marshal(x)
	case MonikerRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MonikerOptions MonikerRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_monikerProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MonikerOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 MonikerRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MonikerOptions MonikerRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_notebookDocumentSync) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case NotebookDocumentSyncOptions:
		return json.Marshal(x)
	case NotebookDocumentSyncRegistrationOptions:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [NotebookDocumentSyncOptions NotebookDocumentSyncRegistrationOptions]", t)
}

func (t *Or_ServerCapabilities_notebookDocumentSync) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 NotebookDocumentSyncOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 NotebookDocumentSyncRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [NotebookDocumentSyncOptions NotebookDocumentSyncRegistrationOptions]"}
}

func (t Or_ServerCapabilities_referencesProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case ReferenceOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [ReferenceOptions bool]", t)
}

func (t *Or_ServerCapabilities_referencesProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 ReferenceOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [ReferenceOptions bool]"}
}

func (t Or_ServerCapabilities_renameProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case RenameOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [RenameOptions bool]", t)
}

func (t *Or_ServerCapabilities_renameProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 RenameOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [RenameOptions bool]"}
}

func (t Or_ServerCapabilities_selectionRangeProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case SelectionRangeOptions:
		return json.Marshal(x)
	case SelectionRangeRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [SelectionRangeOptions SelectionRangeRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_selectionRangeProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 SelectionRangeOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 SelectionRangeRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [SelectionRangeOptions SelectionRangeRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_semanticTokensProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case SemanticTokensOptions:
		return json.Marshal(x)
	case SemanticTokensRegistrationOptions:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [SemanticTokensOptions SemanticTokensRegistrationOptions]", t)
}

func (t *Or_ServerCapabilities_semanticTokensProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 SemanticTokensOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 SemanticTokensRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [SemanticTokensOptions SemanticTokensRegistrationOptions]"}
}

func (t Or_ServerCapabilities_textDocumentSync) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case TextDocumentSyncKind:
		return json.Marshal(x)
	case TextDocumentSyncOptions:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [TextDocumentSyncKind TextDocumentSyncOptions]", t)
}

func (t *Or_ServerCapabilities_textDocumentSync) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 TextDocumentSyncKind
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TextDocumentSyncOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [TextDocumentSyncKind TextDocumentSyncOptions]"}
}

func (t Or_ServerCapabilities_typeDefinitionProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case TypeDefinitionOptions:
		return json.Marshal(x)
	case TypeDefinitionRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [TypeDefinitionOptions TypeDefinitionRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_typeDefinitionProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 TypeDefinitionOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TypeDefinitionRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [TypeDefinitionOptions TypeDefinitionRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_typeHierarchyProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case TypeHierarchyOptions:
		return json.Marshal(x)
	case TypeHierarchyRegistrationOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [TypeHierarchyOptions TypeHierarchyRegistrationOptions bool]", t)
}

func (t *Or_ServerCapabilities_typeHierarchyProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 TypeHierarchyOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TypeHierarchyRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 bool
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [TypeHierarchyOptions TypeHierarchyRegistrationOptions bool]"}
}

func (t Or_ServerCapabilities_workspaceSymbolProvider) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case WorkspaceSymbolOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [WorkspaceSymbolOptions bool]", t)
}

func (t *Or_ServerCapabilities_workspaceSymbolProvider) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 WorkspaceSymbolOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [WorkspaceSymbolOptions bool]"}
}

func (t Or_SignatureInformation_documentation) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case MarkupContent:
		return json.Marshal(x)
	case string:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [MarkupContent string]", t)
}

func (t *Or_SignatureInformation_documentation) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 MarkupContent
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 string
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [MarkupContent string]"}
}

func (t Or_TextDocumentEdit_edits_Elem) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case AnnotatedTextEdit:
		return json.Marshal(x)
	case SnippetTextEdit:
		return json.Marshal(x)
	case TextEdit:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [AnnotatedTextEdit SnippetTextEdit TextEdit]", t)
}

func (t *Or_TextDocumentEdit_edits_Elem) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 AnnotatedTextEdit
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 SnippetTextEdit
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 TextEdit
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [AnnotatedTextEdit SnippetTextEdit TextEdit]"}
}

func (t Or_TextDocumentFilter) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case TextDocumentFilterLanguage:
		return json.Marshal(x)
	case TextDocumentFilterPattern:
		return json.Marshal(x)
	case TextDocumentFilterScheme:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [TextDocumentFilterLanguage TextDocumentFilterPattern TextDocumentFilterScheme]", t)
}

func (t *Or_TextDocumentFilter) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 TextDocumentFilterLanguage
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TextDocumentFilterPattern
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 TextDocumentFilterScheme
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [TextDocumentFilterLanguage TextDocumentFilterPattern TextDocumentFilterScheme]"}
}

func (t Or_TextDocumentSyncOptions_save) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case SaveOptions:
		return json.Marshal(x)
	case bool:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [SaveOptions bool]", t)
}

func (t *Or_TextDocumentSyncOptions_save) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 SaveOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 bool
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [SaveOptions bool]"}
}

func (t Or_WorkspaceDocumentDiagnosticReport) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case WorkspaceFullDocumentDiagnosticReport:
		return json.Marshal(x)
	case WorkspaceUnchangedDocumentDiagnosticReport:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [WorkspaceFullDocumentDiagnosticReport WorkspaceUnchangedDocumentDiagnosticReport]", t)
}

func (t *Or_WorkspaceDocumentDiagnosticReport) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 WorkspaceFullDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 WorkspaceUnchangedDocumentDiagnosticReport
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [WorkspaceFullDocumentDiagnosticReport WorkspaceUnchangedDocumentDiagnosticReport]"}
}

func (t Or_WorkspaceEdit_documentChanges_Elem) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case CreateFile:
		return json.Marshal(x)
	case DeleteFile:
		return json.Marshal(x)
	case RenameFile:
		return json.Marshal(x)
	case TextDocumentEdit:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [CreateFile DeleteFile RenameFile TextDocumentEdit]", t)
}

func (t *Or_WorkspaceEdit_documentChanges_Elem) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 CreateFile
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 DeleteFile
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	var h2 RenameFile
	if err := json.Unmarshal(x, &h2); err == nil {
		t.Value = h2
		return nil
	}
	var h3 TextDocumentEdit
	if err := json.Unmarshal(x, &h3); err == nil {
		t.Value = h3
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [CreateFile DeleteFile RenameFile TextDocumentEdit]"}
}

func (t Or_WorkspaceOptions_textDocumentContent) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case TextDocumentContentOptions:
		return json.Marshal(x)
	case TextDocumentContentRegistrationOptions:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [TextDocumentContentOptions TextDocumentContentRegistrationOptions]", t)
}

func (t *Or_WorkspaceOptions_textDocumentContent) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 TextDocumentContentOptions
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 TextDocumentContentRegistrationOptions
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [TextDocumentContentOptions TextDocumentContentRegistrationOptions]"}
}

func (t Or_textDocument_declaration) MarshalJSON() ([]byte, error) {
	switch x := t.Value.(type) {
	case Declaration:
		return json.Marshal(x)
	case []DeclarationLink:
		return json.Marshal(x)
	case nil:
		return []byte("null"), nil
	}
	return nil, fmt.Errorf("type %T not one of [Declaration []DeclarationLink]", t)
}

func (t *Or_textDocument_declaration) UnmarshalJSON(x []byte) error {
	if string(x) == "null" {
		t.Value = nil
		return nil
	}
	var h0 Declaration
	if err := json.Unmarshal(x, &h0); err == nil {
		t.Value = h0
		return nil
	}
	var h1 []DeclarationLink
	if err := json.Unmarshal(x, &h1); err == nil {
		t.Value = h1
		return nil
	}
	return &UnmarshalError{"unmarshal failed to match one of [Declaration []DeclarationLink]"}
}


================================================
FILE: gopls/internal/protocol/tsprotocol.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated for LSP. DO NOT EDIT.

package protocol

// Code generated from protocol/metaModel.json at ref release/protocol/3.17.6-next.14 (hash 66a087310eea0d60495ba3578d78f70409c403d9).
// https://github.com/microsoft/vscode-languageserver-node/blob/release/protocol/3.17.6-next.14/protocol/metaModel.json
// LSP metaData.version = 3.17.0.

import "encoding/json"

// A special text edit with an additional change annotation.
//
// @since 3.16.0.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#annotatedTextEdit
type AnnotatedTextEdit struct {
	// The actual identifier of the change annotation
	AnnotationID *ChangeAnnotationIdentifier `json:"annotationId,omitempty"`
	TextEdit
}

// Defines how values from a set of defaults and an individual item will be
// merged.
//
// @since 3.18.0
type ApplyKind uint32

// The parameters passed via an apply workspace edit request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#applyWorkspaceEditParams
type ApplyWorkspaceEditParams struct {
	// An optional label of the workspace edit. This label is
	// presented in the user interface for example on an undo
	// stack to undo the workspace edit.
	Label string `json:"label,omitempty"`
	// The edits to apply.
	Edit WorkspaceEdit `json:"edit"`
	// Additional data about the edit.
	//
	// @since 3.18.0
	// @proposed
	Metadata *WorkspaceEditMetadata `json:"metadata,omitempty"`
}

// The result returned from the apply workspace edit request.
//
// @since 3.17 renamed from ApplyWorkspaceEditResponse
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#applyWorkspaceEditResult
type ApplyWorkspaceEditResult struct {
	// Indicates whether the edit was applied or not.
	Applied bool `json:"applied"`
	// An optional textual description for why the edit was not applied.
	// This may be used by the server for diagnostic logging or to provide
	// a suitable error for a request that triggered the edit.
	FailureReason string `json:"failureReason,omitempty"`
	// Depending on the client's failure handling strategy `failedChange` might
	// contain the index of the change that failed. This property is only available
	// if the client signals a `failureHandlingStrategy` in its client capabilities.
	FailedChange uint32 `json:"failedChange"`
}

// A base for all symbol information.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#baseSymbolInformation
type BaseSymbolInformation struct {
	// The name of this symbol.
	Name string `json:"name"`
	// The kind of this symbol.
	Kind SymbolKind `json:"kind"`
	// Tags for this symbol.
	//
	// @since 3.16.0
	Tags []SymbolTag `json:"tags,omitempty"`
	// The name of the symbol containing this symbol. This information is for
	// user interface purposes (e.g. to render a qualifier in the user interface
	// if necessary). It can't be used to re-infer a hierarchy for the document
	// symbols.
	ContainerName string `json:"containerName,omitempty"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyClientCapabilities
type CallHierarchyClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Represents an incoming call, e.g. a caller of a method or constructor.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyIncomingCall
type CallHierarchyIncomingCall struct {
	// The item that makes the call.
	From CallHierarchyItem `json:"from"`
	// The ranges at which the calls appear. This is relative to the caller
	// denoted by {@link CallHierarchyIncomingCall.from `this.from`}.
	FromRanges []Range `json:"fromRanges"`
}

// The parameter of a `callHierarchy/incomingCalls` request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyIncomingCallsParams
type CallHierarchyIncomingCallsParams struct {
	Item CallHierarchyItem `json:"item"`
	WorkDoneProgressParams
	PartialResultParams
}

// Represents programming constructs like functions or constructors in the context
// of call hierarchy.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyItem
type CallHierarchyItem struct {
	// The name of this item.
	Name string `json:"name"`
	// The kind of this item.
	Kind SymbolKind `json:"kind"`
	// Tags for this item.
	Tags []SymbolTag `json:"tags,omitempty"`
	// More detail for this item, e.g. the signature of a function.
	Detail string `json:"detail,omitempty"`
	// The resource identifier of this item.
	URI DocumentURI `json:"uri"`
	// The range enclosing this symbol not including leading/trailing whitespace but everything else, e.g. comments and code.
	Range Range `json:"range"`
	// The range that should be selected and revealed when this symbol is being picked, e.g. the name of a function.
	// Must be contained by the {@link CallHierarchyItem.range `range`}.
	SelectionRange Range `json:"selectionRange"`
	// A data entry field that is preserved between a call hierarchy prepare and
	// incoming calls or outgoing calls requests.
	Data any `json:"data,omitempty"`
}

// Call hierarchy options used during static registration.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyOptions
type CallHierarchyOptions struct {
	WorkDoneProgressOptions
}

// Represents an outgoing call, e.g. calling a getter from a method or a method from a constructor etc.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyOutgoingCall
type CallHierarchyOutgoingCall struct {
	// The item that is called.
	To CallHierarchyItem `json:"to"`
	// The range at which this item is called. This is the range relative to the caller, e.g the item
	// passed to {@link CallHierarchyItemProvider.provideCallHierarchyOutgoingCalls `provideCallHierarchyOutgoingCalls`}
	// and not {@link CallHierarchyOutgoingCall.to `this.to`}.
	FromRanges []Range `json:"fromRanges"`
}

// The parameter of a `callHierarchy/outgoingCalls` request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyOutgoingCallsParams
type CallHierarchyOutgoingCallsParams struct {
	Item CallHierarchyItem `json:"item"`
	WorkDoneProgressParams
	PartialResultParams
}

// The parameter of a `textDocument/prepareCallHierarchy` request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyPrepareParams
type CallHierarchyPrepareParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Call hierarchy options used during static or dynamic registration.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchyRegistrationOptions
type CallHierarchyRegistrationOptions struct {
	TextDocumentRegistrationOptions
	CallHierarchyOptions
	StaticRegistrationOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#cancelParams
type CancelParams struct {
	// The request id to cancel.
	ID any `json:"id"`
}

// Additional information that describes document changes.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#changeAnnotation
type ChangeAnnotation struct {
	// A human-readable string describing the actual change. The string
	// is rendered prominent in the user interface.
	Label string `json:"label"`
	// A flag which indicates that user confirmation is needed
	// before applying the change.
	NeedsConfirmation bool `json:"needsConfirmation,omitempty"`
	// A human-readable string which is rendered less prominent in
	// the user interface.
	Description string `json:"description,omitempty"`
}

// An identifier to refer to a change annotation stored with a workspace edit.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#changeAnnotationIdentifier
type ChangeAnnotationIdentifier = string // (alias)
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#changeAnnotationsSupportOptions
type ChangeAnnotationsSupportOptions struct {
	// Whether the client groups edits with equal labels into tree nodes,
	// for instance all edits labelled with "Changes in Strings" would
	// be a tree node.
	GroupsOnLabel bool `json:"groupsOnLabel,omitempty"`
}

// Defines the capabilities provided by the client.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCapabilities
type ClientCapabilities struct {
	// Workspace specific client capabilities.
	Workspace WorkspaceClientCapabilities `json:"workspace,omitempty"`
	// Text document specific client capabilities.
	TextDocument TextDocumentClientCapabilities `json:"textDocument,omitempty"`
	// Capabilities specific to the notebook document support.
	//
	// @since 3.17.0
	NotebookDocument *NotebookDocumentClientCapabilities `json:"notebookDocument,omitempty"`
	// Window specific client capabilities.
	Window WindowClientCapabilities `json:"window,omitempty"`
	// General client capabilities.
	//
	// @since 3.16.0
	General *GeneralClientCapabilities `json:"general,omitempty"`
	// Experimental client capabilities.
	Experimental any `json:"experimental,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCodeActionKindOptions
type ClientCodeActionKindOptions struct {
	// The code action kind values the client supports. When this
	// property exists the client also guarantees that it will
	// handle values outside its set gracefully and falls back
	// to a default value when unknown.
	ValueSet []CodeActionKind `json:"valueSet"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCodeActionLiteralOptions
type ClientCodeActionLiteralOptions struct {
	// The code action kind is support with the following value
	// set.
	CodeActionKind ClientCodeActionKindOptions `json:"codeActionKind"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCodeActionResolveOptions
type ClientCodeActionResolveOptions struct {
	// The properties that a client can resolve lazily.
	Properties []string `json:"properties"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCodeLensResolveOptions
type ClientCodeLensResolveOptions struct {
	// The properties that a client can resolve lazily.
	Properties []string `json:"properties"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCompletionItemInsertTextModeOptions
type ClientCompletionItemInsertTextModeOptions struct {
	ValueSet []InsertTextMode `json:"valueSet"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCompletionItemOptions
type ClientCompletionItemOptions struct {
	// Client supports snippets as insert text.
	//
	// A snippet can define tab stops and placeholders with `$1`, `$2`
	// and `${3:foo}`. `$0` defines the final tab stop, it defaults to
	// the end of the snippet. Placeholders with equal identifiers are linked,
	// that is typing in one will update others too.
	SnippetSupport bool `json:"snippetSupport,omitempty"`
	// Client supports commit characters on a completion item.
	CommitCharactersSupport bool `json:"commitCharactersSupport,omitempty"`
	// Client supports the following content formats for the documentation
	// property. The order describes the preferred format of the client.
	DocumentationFormat []MarkupKind `json:"documentationFormat,omitempty"`
	// Client supports the deprecated property on a completion item.
	DeprecatedSupport bool `json:"deprecatedSupport,omitempty"`
	// Client supports the preselect property on a completion item.
	PreselectSupport bool `json:"preselectSupport,omitempty"`
	// Client supports the tag property on a completion item. Clients supporting
	// tags have to handle unknown tags gracefully. Clients especially need to
	// preserve unknown tags when sending a completion item back to the server in
	// a resolve call.
	//
	// @since 3.15.0
	TagSupport *CompletionItemTagOptions `json:"tagSupport,omitempty"`
	// Client support insert replace edit to control different behavior if a
	// completion item is inserted in the text or should replace text.
	//
	// @since 3.16.0
	InsertReplaceSupport bool `json:"insertReplaceSupport,omitempty"`
	// Indicates which properties a client can resolve lazily on a completion
	// item. Before version 3.16.0 only the predefined properties `documentation`
	// and `details` could be resolved lazily.
	//
	// @since 3.16.0
	ResolveSupport *ClientCompletionItemResolveOptions `json:"resolveSupport,omitempty"`
	// The client supports the `insertTextMode` property on
	// a completion item to override the whitespace handling mode
	// as defined by the client (see `insertTextMode`).
	//
	// @since 3.16.0
	InsertTextModeSupport *ClientCompletionItemInsertTextModeOptions `json:"insertTextModeSupport,omitempty"`
	// The client has support for completion item label
	// details (see also `CompletionItemLabelDetails`).
	//
	// @since 3.17.0
	LabelDetailsSupport bool `json:"labelDetailsSupport,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCompletionItemOptionsKind
type ClientCompletionItemOptionsKind struct {
	// The completion item kind values the client supports. When this
	// property exists the client also guarantees that it will
	// handle values outside its set gracefully and falls back
	// to a default value when unknown.
	//
	// If this property is not present the client only supports
	// the completion items kinds from `Text` to `Reference` as defined in
	// the initial version of the protocol.
	ValueSet []CompletionItemKind `json:"valueSet,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientCompletionItemResolveOptions
type ClientCompletionItemResolveOptions struct {
	// The properties that a client can resolve lazily.
	Properties []string `json:"properties"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientDiagnosticsTagOptions
type ClientDiagnosticsTagOptions struct {
	// The tags supported by the client.
	ValueSet []DiagnosticTag `json:"valueSet"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientFoldingRangeKindOptions
type ClientFoldingRangeKindOptions struct {
	// The folding range kind values the client supports. When this
	// property exists the client also guarantees that it will
	// handle values outside its set gracefully and falls back
	// to a default value when unknown.
	ValueSet []FoldingRangeKind `json:"valueSet,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientFoldingRangeOptions
type ClientFoldingRangeOptions struct {
	// If set, the client signals that it supports setting collapsedText on
	// folding ranges to display custom labels instead of the default text.
	//
	// @since 3.17.0
	CollapsedText bool `json:"collapsedText,omitempty"`
}

// Information about the client
//
// @since 3.15.0
// @since 3.18.0 ClientInfo type name added.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientInfo
type ClientInfo struct {
	// The name of the client as defined by the client.
	Name string `json:"name"`
	// The client's version as defined by the client.
	Version string `json:"version,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientInlayHintResolveOptions
type ClientInlayHintResolveOptions struct {
	// The properties that a client can resolve lazily.
	Properties []string `json:"properties"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSemanticTokensRequestFullDelta
type ClientSemanticTokensRequestFullDelta struct {
	// The client will send the `textDocument/semanticTokens/full/delta` request if
	// the server provides a corresponding handler.
	Delta bool `json:"delta,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSemanticTokensRequestOptions
type ClientSemanticTokensRequestOptions struct {
	// The client will send the `textDocument/semanticTokens/range` request if
	// the server provides a corresponding handler.
	Range *Or_ClientSemanticTokensRequestOptions_range `json:"range,omitempty"`
	// The client will send the `textDocument/semanticTokens/full` request if
	// the server provides a corresponding handler.
	Full *Or_ClientSemanticTokensRequestOptions_full `json:"full,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientShowMessageActionItemOptions
type ClientShowMessageActionItemOptions struct {
	// Whether the client supports additional attributes which
	// are preserved and send back to the server in the
	// request's response.
	AdditionalPropertiesSupport bool `json:"additionalPropertiesSupport,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSignatureInformationOptions
type ClientSignatureInformationOptions struct {
	// Client supports the following content formats for the documentation
	// property. The order describes the preferred format of the client.
	DocumentationFormat []MarkupKind `json:"documentationFormat,omitempty"`
	// Client capabilities specific to parameter information.
	ParameterInformation *ClientSignatureParameterInformationOptions `json:"parameterInformation,omitempty"`
	// The client supports the `activeParameter` property on `SignatureInformation`
	// literal.
	//
	// @since 3.16.0
	ActiveParameterSupport bool `json:"activeParameterSupport,omitempty"`
	// The client supports the `activeParameter` property on
	// `SignatureHelp`/`SignatureInformation` being set to `null` to
	// indicate that no parameter should be active.
	//
	// @since 3.18.0
	// @proposed
	NoActiveParameterSupport bool `json:"noActiveParameterSupport,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSignatureParameterInformationOptions
type ClientSignatureParameterInformationOptions struct {
	// The client supports processing label offsets instead of a
	// simple label string.
	//
	// @since 3.14.0
	LabelOffsetSupport bool `json:"labelOffsetSupport,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSymbolKindOptions
type ClientSymbolKindOptions struct {
	// The symbol kind values the client supports. When this
	// property exists the client also guarantees that it will
	// handle values outside its set gracefully and falls back
	// to a default value when unknown.
	//
	// If this property is not present the client only supports
	// the symbol kinds from `File` to `Array` as defined in
	// the initial version of the protocol.
	ValueSet []SymbolKind `json:"valueSet,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSymbolResolveOptions
type ClientSymbolResolveOptions struct {
	// The properties that a client can resolve lazily. Usually
	// `location.range`
	Properties []string `json:"properties"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#clientSymbolTagOptions
type ClientSymbolTagOptions struct {
	// The tags supported by the client.
	ValueSet []SymbolTag `json:"valueSet"`
}

// A code action represents a change that can be performed in code, e.g. to fix a problem or
// to refactor code.
//
// A CodeAction must set either `edit` and/or a `command`. If both are supplied, the `edit` is applied first, then the `command` is executed.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeAction
type CodeAction struct {
	// A short, human-readable, title for this code action.
	Title string `json:"title"`
	// The kind of the code action.
	//
	// Used to filter code actions.
	Kind CodeActionKind `json:"kind,omitempty"`
	// The diagnostics that this code action resolves.
	Diagnostics []Diagnostic `json:"diagnostics,omitempty"`
	// Marks this as a preferred action. Preferred actions are used by the `auto fix` command and can be targeted
	// by keybindings.
	//
	// A quick fix should be marked preferred if it properly addresses the underlying error.
	// A refactoring should be marked preferred if it is the most reasonable choice of actions to take.
	//
	// @since 3.15.0
	IsPreferred bool `json:"isPreferred,omitempty"`
	// Marks that the code action cannot currently be applied.
	//
	// Clients should follow the following guidelines regarding disabled code actions:
	//
	//   - Disabled code actions are not shown in automatic [lightbulbs](https://code.visualstudio.com/docs/editor/editingevolved#_code-action)
	//     code action menus.
	//
	//   - Disabled actions are shown as faded out in the code action menu when the user requests a more specific type
	//     of code action, such as refactorings.
	//
	//   - If the user has a [keybinding](https://code.visualstudio.com/docs/editor/refactoring#_keybindings-for-code-actions)
	//     that auto applies a code action and only disabled code actions are returned, the client should show the user an
	//     error message with `reason` in the editor.
	//
	// @since 3.16.0
	Disabled *CodeActionDisabled `json:"disabled,omitempty"`
	// The workspace edit this code action performs.
	Edit *WorkspaceEdit `json:"edit,omitempty"`
	// A command this code action executes. If a code action
	// provides an edit and a command, first the edit is
	// executed and then the command.
	Command *Command `json:"command,omitempty"`
	// A data entry field that is preserved on a code action between
	// a `textDocument/codeAction` and a `codeAction/resolve` request.
	//
	// @since 3.16.0
	Data *json.RawMessage `json:"data,omitempty"`
	// Tags for this code action.
	//
	// @since 3.18.0 - proposed
	Tags []CodeActionTag `json:"tags,omitempty"`
}

// The Client Capabilities of a {@link CodeActionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionClientCapabilities
type CodeActionClientCapabilities struct {
	// Whether code action supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client support code action literals of type `CodeAction` as a valid
	// response of the `textDocument/codeAction` request. If the property is not
	// set the request can only return `Command` literals.
	//
	// @since 3.8.0
	CodeActionLiteralSupport ClientCodeActionLiteralOptions `json:"codeActionLiteralSupport,omitempty"`
	// Whether code action supports the `isPreferred` property.
	//
	// @since 3.15.0
	IsPreferredSupport bool `json:"isPreferredSupport,omitempty"`
	// Whether code action supports the `disabled` property.
	//
	// @since 3.16.0
	DisabledSupport bool `json:"disabledSupport,omitempty"`
	// Whether code action supports the `data` property which is
	// preserved between a `textDocument/codeAction` and a
	// `codeAction/resolve` request.
	//
	// @since 3.16.0
	DataSupport bool `json:"dataSupport,omitempty"`
	// Whether the client supports resolving additional code action
	// properties via a separate `codeAction/resolve` request.
	//
	// @since 3.16.0
	ResolveSupport *ClientCodeActionResolveOptions `json:"resolveSupport,omitempty"`
	// Whether the client honors the change annotations in
	// text edits and resource operations returned via the
	// `CodeAction#edit` property by for example presenting
	// the workspace edit in the user interface and asking
	// for confirmation.
	//
	// @since 3.16.0
	HonorsChangeAnnotations bool `json:"honorsChangeAnnotations,omitempty"`
	// Whether the client supports documentation for a class of
	// code actions.
	//
	// @since 3.18.0
	// @proposed
	DocumentationSupport bool `json:"documentationSupport,omitempty"`
	// Client supports the tag property on a code action. Clients
	// supporting tags have to handle unknown tags gracefully.
	//
	// @since 3.18.0 - proposed
	TagSupport *CodeActionTagOptions `json:"tagSupport,omitempty"`
}

// Contains additional diagnostic information about the context in which
// a {@link CodeActionProvider.provideCodeActions code action} is run.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionContext
type CodeActionContext struct {
	// An array of diagnostics known on the client side overlapping the range provided to the
	// `textDocument/codeAction` request. They are provided so that the server knows which
	// errors are currently presented to the user for the given range. There is no guarantee
	// that these accurately reflect the error state of the resource. The primary parameter
	// to compute code actions is the provided range.
	Diagnostics []Diagnostic `json:"diagnostics"`
	// Requested kind of actions to return.
	//
	// Actions not of this kind are filtered out by the client before being shown. So servers
	// can omit computing them.
	Only []CodeActionKind `json:"only,omitempty"`
	// The reason why code actions were requested.
	//
	// @since 3.17.0
	TriggerKind *CodeActionTriggerKind `json:"triggerKind,omitempty"`
}

// Captures why the code action is currently disabled.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionDisabled
type CodeActionDisabled struct {
	// Human readable description of why the code action is currently disabled.
	//
	// This is displayed in the code actions UI.
	Reason string `json:"reason"`
}

// A set of predefined code action kinds
type CodeActionKind string

// Documentation for a class of code actions.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionKindDocumentation
type CodeActionKindDocumentation struct {
	// The kind of the code action being documented.
	//
	// If the kind is generic, such as `CodeActionKind.Refactor`, the documentation will be shown whenever any
	// refactorings are returned. If the kind if more specific, such as `CodeActionKind.RefactorExtract`, the
	// documentation will only be shown when extract refactoring code actions are returned.
	Kind CodeActionKind `json:"kind"`
	// Command that is ued to display the documentation to the user.
	//
	// The title of this documentation code action is taken from {@linkcode Command.title}
	Command Command `json:"command"`
}

// Provider options for a {@link CodeActionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionOptions
type CodeActionOptions struct {
	// CodeActionKinds that this server may return.
	//
	// The list of kinds may be generic, such as `CodeActionKind.Refactor`, or the server
	// may list out every specific kind they provide.
	CodeActionKinds []CodeActionKind `json:"codeActionKinds,omitempty"`
	// Static documentation for a class of code actions.
	//
	// Documentation from the provider should be shown in the code actions menu if either:
	//
	//
	//  - Code actions of `kind` are requested by the editor. In this case, the editor will show the documentation that
	//   most closely matches the requested code action kind. For example, if a provider has documentation for
	//   both `Refactor` and `RefactorExtract`, when the user requests code actions for `RefactorExtract`,
	//   the editor will use the documentation for `RefactorExtract` instead of the documentation for `Refactor`.
	//
	//
	//  - Any code actions of `kind` are returned by the provider.
	//
	// At most one documentation entry should be shown per provider.
	//
	// @since 3.18.0
	// @proposed
	Documentation []CodeActionKindDocumentation `json:"documentation,omitempty"`
	// The server provides support to resolve additional
	// information for a code action.
	//
	// @since 3.16.0
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link CodeActionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionParams
type CodeActionParams struct {
	// The document in which the command was invoked.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The range for which the command was invoked.
	Range Range `json:"range"`
	// Context carrying additional information.
	Context CodeActionContext `json:"context"`
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link CodeActionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionRegistrationOptions
type CodeActionRegistrationOptions struct {
	TextDocumentRegistrationOptions
	CodeActionOptions
}

// Code action tags are extra annotations that tweak the behavior of a code action.
//
// @since 3.18.0 - proposed
type CodeActionTag uint32

// @since 3.18.0 - proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeActionTagOptions
type CodeActionTagOptions struct {
	// The tags supported by the client.
	ValueSet []CodeActionTag `json:"valueSet"`
}

// The reason why code actions were requested.
//
// @since 3.17.0
type CodeActionTriggerKind uint32

// Structure to capture a description for an error code.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeDescription
type CodeDescription struct {
	// An URI to open with more information about the diagnostic error.
	Href URI `json:"href"`
}

// A code lens represents a {@link Command command} that should be shown along with
// source text, like the number of references, a way to run tests, etc.
//
// A code lens is _unresolved_ when no command is associated to it. For performance
// reasons the creation of a code lens and resolving should be done in two stages.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLens
type CodeLens struct {
	// The range in which this code lens is valid. Should only span a single line.
	Range Range `json:"range"`
	// The command this code lens represents.
	Command *Command `json:"command,omitempty"`
	// A data entry field that is preserved on a code lens item between
	// a {@link CodeLensRequest} and a {@link CodeLensResolveRequest}
	Data any `json:"data,omitempty"`
}

// The client capabilities  of a {@link CodeLensRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLensClientCapabilities
type CodeLensClientCapabilities struct {
	// Whether code lens supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Whether the client supports resolving additional code lens
	// properties via a separate `codeLens/resolve` request.
	//
	// @since 3.18.0
	ResolveSupport *ClientCodeLensResolveOptions `json:"resolveSupport,omitempty"`
}

// Code Lens provider options of a {@link CodeLensRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLensOptions
type CodeLensOptions struct {
	// Code lens has a resolve provider as well.
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link CodeLensRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLensParams
type CodeLensParams struct {
	// The document to request code lens for.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link CodeLensRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLensRegistrationOptions
type CodeLensRegistrationOptions struct {
	TextDocumentRegistrationOptions
	CodeLensOptions
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLensWorkspaceClientCapabilities
type CodeLensWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from the
	// server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// code lenses currently shown. It should be used with absolute care and is
	// useful for situation where a server for example detect a project wide
	// change that requires such a calculation.
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// Represents a color in RGBA space.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#color
type Color struct {
	// The red component of this color in the range [0-1].
	Red float64 `json:"red"`
	// The green component of this color in the range [0-1].
	Green float64 `json:"green"`
	// The blue component of this color in the range [0-1].
	Blue float64 `json:"blue"`
	// The alpha component of this color in the range [0-1].
	Alpha float64 `json:"alpha"`
}

// Represents a color range from a document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#colorInformation
type ColorInformation struct {
	// The range in the document where this color appears.
	Range Range `json:"range"`
	// The actual color value for this color range.
	Color Color `json:"color"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#colorPresentation
type ColorPresentation struct {
	// The label of this color presentation. It will be shown on the color
	// picker header. By default this is also the text that is inserted when selecting
	// this color presentation.
	Label string `json:"label"`
	// An {@link TextEdit edit} which is applied to a document when selecting
	// this presentation for the color.  When `falsy` the {@link ColorPresentation.label label}
	// is used.
	TextEdit *TextEdit `json:"textEdit,omitempty"`
	// An optional array of additional {@link TextEdit text edits} that are applied when
	// selecting this color presentation. Edits must not overlap with the main {@link ColorPresentation.textEdit edit} nor with themselves.
	AdditionalTextEdits []TextEdit `json:"additionalTextEdits,omitempty"`
}

// Parameters for a {@link ColorPresentationRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#colorPresentationParams
type ColorPresentationParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The color to request presentations for.
	Color Color `json:"color"`
	// The range where the color would be inserted. Serves as a context.
	Range Range `json:"range"`
	WorkDoneProgressParams
	PartialResultParams
}

// Represents a reference to a command. Provides a title which
// will be used to represent a command in the UI and, optionally,
// an array of arguments which will be passed to the command handler
// function when invoked.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#command
type Command struct {
	// Title of the command, like `save`.
	Title string `json:"title"`
	// An optional tooltip.
	//
	// @since 3.18.0
	// @proposed
	Tooltip string `json:"tooltip,omitempty"`
	// The identifier of the actual command handler.
	Command string `json:"command"`
	// Arguments that the command handler should be
	// invoked with.
	Arguments []json.RawMessage `json:"arguments,omitempty"`
}

// Completion client capabilities
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionClientCapabilities
type CompletionClientCapabilities struct {
	// Whether completion supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports the following `CompletionItem` specific
	// capabilities.
	CompletionItem     ClientCompletionItemOptions      `json:"completionItem,omitempty"`
	CompletionItemKind *ClientCompletionItemOptionsKind `json:"completionItemKind,omitempty"`
	// Defines how the client handles whitespace and indentation
	// when accepting a completion item that uses multi line
	// text in either `insertText` or `textEdit`.
	//
	// @since 3.17.0
	InsertTextMode InsertTextMode `json:"insertTextMode,omitempty"`
	// The client supports to send additional context information for a
	// `textDocument/completion` request.
	ContextSupport bool `json:"contextSupport,omitempty"`
	// The client supports the following `CompletionList` specific
	// capabilities.
	//
	// @since 3.17.0
	CompletionList *CompletionListCapabilities `json:"completionList,omitempty"`
}

// Contains additional information about the context in which a completion request is triggered.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionContext
type CompletionContext struct {
	// How the completion was triggered.
	TriggerKind CompletionTriggerKind `json:"triggerKind"`
	// The trigger character (a single character) that has trigger code complete.
	// Is undefined if `triggerKind !== CompletionTriggerKind.TriggerCharacter`
	TriggerCharacter string `json:"triggerCharacter,omitempty"`
}

// A completion item represents a text snippet that is
// proposed to complete text that is being typed.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItem
type CompletionItem struct {
	// The label of this completion item.
	//
	// The label property is also by default the text that
	// is inserted when selecting this completion.
	//
	// If label details are provided the label itself should
	// be an unqualified name of the completion item.
	Label string `json:"label"`
	// Additional details for the label
	//
	// @since 3.17.0
	LabelDetails *CompletionItemLabelDetails `json:"labelDetails,omitempty"`
	// The kind of this completion item. Based of the kind
	// an icon is chosen by the editor.
	Kind CompletionItemKind `json:"kind,omitempty"`
	// Tags for this completion item.
	//
	// @since 3.15.0
	Tags []CompletionItemTag `json:"tags,omitempty"`
	// A human-readable string with additional information
	// about this item, like type or symbol information.
	Detail string `json:"detail,omitempty"`
	// A human-readable string that represents a doc-comment.
	Documentation *Or_CompletionItem_documentation `json:"documentation,omitempty"`
	// Indicates if this item is deprecated.
	// @deprecated Use `tags` instead.
	Deprecated bool `json:"deprecated,omitempty"`
	// Select this item when showing.
	//
	// *Note* that only one completion item can be selected and that the
	// tool / client decides which item that is. The rule is that the *first*
	// item of those that match best is selected.
	Preselect bool `json:"preselect,omitempty"`
	// A string that should be used when comparing this item
	// with other items. When `falsy` the {@link CompletionItem.label label}
	// is used.
	SortText string `json:"sortText,omitempty"`
	// A string that should be used when filtering a set of
	// completion items. When `falsy` the {@link CompletionItem.label label}
	// is used.
	FilterText string `json:"filterText,omitempty"`
	// A string that should be inserted into a document when selecting
	// this completion. When `falsy` the {@link CompletionItem.label label}
	// is used.
	//
	// The `insertText` is subject to interpretation by the client side.
	// Some tools might not take the string literally. For example
	// VS Code when code complete is requested in this example
	// `con<cursor position>` and a completion item with an `insertText` of
	// `console` is provided it will only insert `sole`. Therefore it is
	// recommended to use `textEdit` instead since it avoids additional client
	// side interpretation.
	InsertText string `json:"insertText,omitempty"`
	// The format of the insert text. The format applies to both the
	// `insertText` property and the `newText` property of a provided
	// `textEdit`. If omitted defaults to `InsertTextFormat.PlainText`.
	//
	// Please note that the insertTextFormat doesn't apply to
	// `additionalTextEdits`.
	InsertTextFormat *InsertTextFormat `json:"insertTextFormat,omitempty"`
	// How whitespace and indentation is handled during completion
	// item insertion. If not provided the clients default value depends on
	// the `textDocument.completion.insertTextMode` client capability.
	//
	// @since 3.16.0
	InsertTextMode *InsertTextMode `json:"insertTextMode,omitempty"`
	// An {@link TextEdit edit} which is applied to a document when selecting
	// this completion. When an edit is provided the value of
	// {@link CompletionItem.insertText insertText} is ignored.
	//
	// Most editors support two different operations when accepting a completion
	// item. One is to insert a completion text and the other is to replace an
	// existing text with a completion text. Since this can usually not be
	// predetermined by a server it can report both ranges. Clients need to
	// signal support for `InsertReplaceEdits` via the
	// `textDocument.completion.insertReplaceSupport` client capability
	// property.
	//
	// *Note 1:* The text edit's range as well as both ranges from an insert
	// replace edit must be a [single line] and they must contain the position
	// at which completion has been requested.
	// *Note 2:* If an `InsertReplaceEdit` is returned the edit's insert range
	// must be a prefix of the edit's replace range, that means it must be
	// contained and starting at the same position.
	//
	// @since 3.16.0 additional type `InsertReplaceEdit`
	TextEdit *Or_CompletionItem_textEdit `json:"textEdit,omitempty"`
	// The edit text used if the completion item is part of a CompletionList and
	// CompletionList defines an item default for the text edit range.
	//
	// Clients will only honor this property if they opt into completion list
	// item defaults using the capability `completionList.itemDefaults`.
	//
	// If not provided and a list's default range is provided the label
	// property is used as a text.
	//
	// @since 3.17.0
	TextEditText string `json:"textEditText,omitempty"`
	// An optional array of additional {@link TextEdit text edits} that are applied when
	// selecting this completion. Edits must not overlap (including the same insert position)
	// with the main {@link CompletionItem.textEdit edit} nor with themselves.
	//
	// Additional text edits should be used to change text unrelated to the current cursor position
	// (for example adding an import statement at the top of the file if the completion item will
	// insert an unqualified type).
	AdditionalTextEdits []TextEdit `json:"additionalTextEdits,omitempty"`
	// An optional set of characters that when pressed while this completion is active will accept it first and
	// then type that character. *Note* that all commit characters should have `length=1` and that superfluous
	// characters will be ignored.
	CommitCharacters []string `json:"commitCharacters,omitempty"`
	// An optional {@link Command command} that is executed *after* inserting this completion. *Note* that
	// additional modifications to the current document should be described with the
	// {@link CompletionItem.additionalTextEdits additionalTextEdits}-property.
	Command *Command `json:"command,omitempty"`
	// A data entry field that is preserved on a completion item between a
	// {@link CompletionRequest} and a {@link CompletionResolveRequest}.
	Data any `json:"data,omitempty"`
}

// Specifies how fields from a completion item should be combined with those
// from `completionList.itemDefaults`.
//
// If unspecified, all fields will be treated as ApplyKind.Replace.
//
// If a field's value is ApplyKind.Replace, the value from a completion item (if
// provided and not `null`) will always be used instead of the value from
// `completionItem.itemDefaults`.
//
// If a field's value is ApplyKind.Merge, the values will be merged using the rules
// defined against each field below.
//
// Servers are only allowed to return `applyKind` if the client
// signals support for this via the `completionList.applyKindSupport`
// capability.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItemApplyKinds
type CompletionItemApplyKinds struct {
	// Specifies whether commitCharacters on a completion will replace or be
	// merged with those in `completionList.itemDefaults.commitCharacters`.
	//
	// If ApplyKind.Replace, the commit characters from the completion item will
	// always be used unless not provided, in which case those from
	// `completionList.itemDefaults.commitCharacters` will be used. An
	// empty list can be used if a completion item does not have any commit
	// characters and also should not use those from
	// `completionList.itemDefaults.commitCharacters`.
	//
	// If ApplyKind.Merge the commitCharacters for the completion will be the
	// union of all values in both `completionList.itemDefaults.commitCharacters`
	// and the completion's own `commitCharacters`.
	//
	// @since 3.18.0
	CommitCharacters *ApplyKind `json:"commitCharacters,omitempty"`
	// Specifies whether the `data` field on a completion will replace or
	// be merged with data from `completionList.itemDefaults.data`.
	//
	// If ApplyKind.Replace, the data from the completion item will be used if
	// provided (and not `null`), otherwise
	// `completionList.itemDefaults.data` will be used. An empty object can
	// be used if a completion item does not have any data but also should
	// not use the value from `completionList.itemDefaults.data`.
	//
	// If ApplyKind.Merge, a shallow merge will be performed between
	// `completionList.itemDefaults.data` and the completion's own data
	// using the following rules:
	//
	//
	//  - If a completion's `data` field is not provided (or `null`), the
	//   entire `data` field from `completionList.itemDefaults.data` will be
	//   used as-is.
	//  - If a completion's `data` field is provided, each field will
	//   overwrite the field of the same name in
	//   `completionList.itemDefaults.data` but no merging of nested fields
	//   within that value will occur.
	//
	// @since 3.18.0
	Data *ApplyKind `json:"data,omitempty"`
}

// In many cases the items of an actual completion result share the same
// value for properties like `commitCharacters` or the range of a text
// edit. A completion list can therefore define item defaults which will
// be used if a completion item itself doesn't specify the value.
//
// If a completion list specifies a default value and a completion item
// also specifies a corresponding value, the rules for combining these are
// defined by `applyKinds` (if the client supports it), defaulting to
// ApplyKind.Replace.
//
// Servers are only allowed to return default values if the client
// signals support for this via the `completionList.itemDefaults`
// capability.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItemDefaults
type CompletionItemDefaults struct {
	// A default commit character set.
	//
	// @since 3.17.0
	CommitCharacters []string `json:"commitCharacters,omitempty"`
	// A default edit range.
	//
	// @since 3.17.0
	EditRange *Or_CompletionItemDefaults_editRange `json:"editRange,omitempty"`
	// A default insert text format.
	//
	// @since 3.17.0
	InsertTextFormat *InsertTextFormat `json:"insertTextFormat,omitempty"`
	// A default insert text mode.
	//
	// @since 3.17.0
	InsertTextMode *InsertTextMode `json:"insertTextMode,omitempty"`
	// A default data value.
	//
	// @since 3.17.0
	Data any `json:"data,omitempty"`
}

// The kind of a completion entry.
type CompletionItemKind uint32

// Additional details for a completion item label.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItemLabelDetails
type CompletionItemLabelDetails struct {
	// An optional string which is rendered less prominently directly after {@link CompletionItem.label label},
	// without any spacing. Should be used for function signatures and type annotations.
	Detail string `json:"detail,omitempty"`
	// An optional string which is rendered less prominently after {@link CompletionItem.detail}. Should be used
	// for fully qualified names and file paths.
	Description string `json:"description,omitempty"`
}

// Completion item tags are extra annotations that tweak the rendering of a completion
// item.
//
// @since 3.15.0
type CompletionItemTag uint32

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItemTagOptions
type CompletionItemTagOptions struct {
	// The tags supported by the client.
	ValueSet []CompletionItemTag `json:"valueSet"`
}

// Represents a collection of {@link CompletionItem completion items} to be presented
// in the editor.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionList
type CompletionList struct {
	// This list it not complete. Further typing results in recomputing this list.
	//
	// Recomputed lists have all their items replaced (not appended) in the
	// incomplete completion sessions.
	IsIncomplete bool `json:"isIncomplete"`
	// In many cases the items of an actual completion result share the same
	// value for properties like `commitCharacters` or the range of a text
	// edit. A completion list can therefore define item defaults which will
	// be used if a completion item itself doesn't specify the value.
	//
	// If a completion list specifies a default value and a completion item
	// also specifies a corresponding value, the rules for combining these are
	// defined by `applyKinds` (if the client supports it), defaulting to
	// ApplyKind.Replace.
	//
	// Servers are only allowed to return default values if the client
	// signals support for this via the `completionList.itemDefaults`
	// capability.
	//
	// @since 3.17.0
	ItemDefaults *CompletionItemDefaults `json:"itemDefaults,omitempty"`
	// Specifies how fields from a completion item should be combined with those
	// from `completionList.itemDefaults`.
	//
	// If unspecified, all fields will be treated as ApplyKind.Replace.
	//
	// If a field's value is ApplyKind.Replace, the value from a completion item
	// (if provided and not `null`) will always be used instead of the value
	// from `completionItem.itemDefaults`.
	//
	// If a field's value is ApplyKind.Merge, the values will be merged using
	// the rules defined against each field below.
	//
	// Servers are only allowed to return `applyKind` if the client
	// signals support for this via the `completionList.applyKindSupport`
	// capability.
	//
	// @since 3.18.0
	ApplyKind *CompletionItemApplyKinds `json:"applyKind,omitempty"`
	// The completion items.
	Items []CompletionItem `json:"items"`
}

// The client supports the following `CompletionList` specific
// capabilities.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionListCapabilities
type CompletionListCapabilities struct {
	// The client supports the following itemDefaults on
	// a completion list.
	//
	// The value lists the supported property names of the
	// `CompletionList.itemDefaults` object. If omitted
	// no properties are supported.
	//
	// @since 3.17.0
	ItemDefaults []string `json:"itemDefaults,omitempty"`
	// Specifies whether the client supports `CompletionList.applyKind` to
	// indicate how supported values from `completionList.itemDefaults`
	// and `completion` will be combined.
	//
	// If a client supports `applyKind` it must support it for all fields
	// that it supports that are listed in `CompletionList.applyKind`. This
	// means when clients add support for new/future fields in completion
	// items the MUST also support merge for them if those fields are
	// defined in `CompletionList.applyKind`.
	//
	// @since 3.18.0
	ApplyKindSupport bool `json:"applyKindSupport,omitempty"`
}

// Completion options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionOptions
type CompletionOptions struct {
	// Most tools trigger completion request automatically without explicitly requesting
	// it using a keyboard shortcut (e.g. Ctrl+Space). Typically they do so when the user
	// starts to type an identifier. For example if the user types `c` in a JavaScript file
	// code complete will automatically pop up present `console` besides others as a
	// completion item. Characters that make up identifiers don't need to be listed here.
	//
	// If code complete should automatically be trigger on characters not being valid inside
	// an identifier (for example `.` in JavaScript) list them in `triggerCharacters`.
	TriggerCharacters []string `json:"triggerCharacters,omitempty"`
	// The list of all possible characters that commit a completion. This field can be used
	// if clients don't support individual commit characters per completion item. See
	// `ClientCapabilities.textDocument.completion.completionItem.commitCharactersSupport`
	//
	// If a server provides both `allCommitCharacters` and commit characters on an individual
	// completion item the ones on the completion item win.
	//
	// @since 3.2.0
	AllCommitCharacters []string `json:"allCommitCharacters,omitempty"`
	// The server provides support to resolve additional
	// information for a completion item.
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	// The server supports the following `CompletionItem` specific
	// capabilities.
	//
	// @since 3.17.0
	CompletionItem *ServerCompletionItemOptions `json:"completionItem,omitempty"`
	WorkDoneProgressOptions
}

// Completion parameters
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionParams
type CompletionParams struct {
	// The completion context. This is only available it the client specifies
	// to send this using the client capability `textDocument.completion.contextSupport === true`
	Context CompletionContext `json:"context,omitempty"`
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link CompletionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionRegistrationOptions
type CompletionRegistrationOptions struct {
	TextDocumentRegistrationOptions
	CompletionOptions
}

// How a completion was triggered
type CompletionTriggerKind uint32

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#configurationItem
type ConfigurationItem struct {
	// The scope to get the configuration section for.
	ScopeURI *URI `json:"scopeUri,omitempty"`
	// The configuration section asked for.
	Section string `json:"section,omitempty"`
}

// The parameters of a configuration request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#configurationParams
type ConfigurationParams struct {
	Items []ConfigurationItem `json:"items"`
}

// Create file operation.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#createFile
type CreateFile struct {
	// A create
	Kind string `json:"kind"`
	// The resource to create.
	URI DocumentURI `json:"uri"`
	// Additional options
	Options *CreateFileOptions `json:"options,omitempty"`
	ResourceOperation
}

// Options to create a file.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#createFileOptions
type CreateFileOptions struct {
	// Overwrite existing file. Overwrite wins over `ignoreIfExists`
	Overwrite bool `json:"overwrite,omitempty"`
	// Ignore if exists.
	IgnoreIfExists bool `json:"ignoreIfExists,omitempty"`
}

// The parameters sent in notifications/requests for user-initiated creation of
// files.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#createFilesParams
type CreateFilesParams struct {
	// An array of all files/folders created in this operation.
	Files []FileCreate `json:"files"`
}

// The declaration of a symbol representation as one or many {@link Location locations}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declaration
type Declaration = []Location // (alias)
// @since 3.14.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declarationClientCapabilities
type DeclarationClientCapabilities struct {
	// Whether declaration supports dynamic registration. If this is set to `true`
	// the client supports the new `DeclarationRegistrationOptions` return value
	// for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports additional metadata in the form of declaration links.
	LinkSupport bool `json:"linkSupport,omitempty"`
}

// Information about where a symbol is declared.
//
// Provides additional metadata over normal {@link Location location} declarations, including the range of
// the declaring symbol.
//
// Servers should prefer returning `DeclarationLink` over `Declaration` if supported
// by the client.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declarationLink
type DeclarationLink = LocationLink // (alias)
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declarationOptions
type DeclarationOptions struct {
	WorkDoneProgressOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declarationParams
type DeclarationParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#declarationRegistrationOptions
type DeclarationRegistrationOptions struct {
	DeclarationOptions
	TextDocumentRegistrationOptions
	StaticRegistrationOptions
}

// The definition of a symbol represented as one or many {@link Location locations}.
// For most programming languages there is only one location at which a symbol is
// defined.
//
// Servers should prefer returning `DefinitionLink` over `Definition` if supported
// by the client.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definition
type Definition = Or_Definition // (alias)
// Client Capabilities for a {@link DefinitionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definitionClientCapabilities
type DefinitionClientCapabilities struct {
	// Whether definition supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports additional metadata in the form of definition links.
	//
	// @since 3.14.0
	LinkSupport bool `json:"linkSupport,omitempty"`
}

// Information about where a symbol is defined.
//
// Provides additional metadata over normal {@link Location location} definitions, including the range of
// the defining symbol
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definitionLink
type DefinitionLink = LocationLink // (alias)
// Server Capabilities for a {@link DefinitionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definitionOptions
type DefinitionOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link DefinitionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definitionParams
type DefinitionParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link DefinitionRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#definitionRegistrationOptions
type DefinitionRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DefinitionOptions
}

// Delete file operation
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#deleteFile
type DeleteFile struct {
	// A delete
	Kind string `json:"kind"`
	// The file to delete.
	URI DocumentURI `json:"uri"`
	// Delete options.
	Options *DeleteFileOptions `json:"options,omitempty"`
	ResourceOperation
}

// Delete file options
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#deleteFileOptions
type DeleteFileOptions struct {
	// Delete the content recursively if a folder is denoted.
	Recursive bool `json:"recursive,omitempty"`
	// Ignore the operation if the file doesn't exist.
	IgnoreIfNotExists bool `json:"ignoreIfNotExists,omitempty"`
}

// The parameters sent in notifications/requests for user-initiated deletes of
// files.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#deleteFilesParams
type DeleteFilesParams struct {
	// An array of all files/folders deleted in this operation.
	Files []FileDelete `json:"files"`
}

// Represents a diagnostic, such as a compiler error or warning. Diagnostic objects
// are only valid in the scope of a resource.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnostic
type Diagnostic struct {
	// The range at which the message applies
	Range Range `json:"range"`
	// The diagnostic's severity. To avoid interpretation mismatches when a
	// server is used with different clients it is highly recommended that servers
	// always provide a severity value.
	Severity DiagnosticSeverity `json:"severity,omitempty"`
	// The diagnostic's code, which usually appear in the user interface.
	Code any `json:"code,omitempty"`
	// An optional property to describe the error code.
	// Requires the code field (above) to be present/not null.
	//
	// @since 3.16.0
	CodeDescription *CodeDescription `json:"codeDescription,omitempty"`
	// A human-readable string describing the source of this
	// diagnostic, e.g. 'typescript' or 'super lint'. It usually
	// appears in the user interface.
	Source string `json:"source,omitempty"`
	// The diagnostic's message. It usually appears in the user interface
	Message string `json:"message"`
	// Additional metadata about the diagnostic.
	//
	// @since 3.15.0
	Tags []DiagnosticTag `json:"tags,omitempty"`
	// An array of related diagnostic information, e.g. when symbol-names within
	// a scope collide all definitions can be marked via this property.
	RelatedInformation []DiagnosticRelatedInformation `json:"relatedInformation,omitempty"`
	// A data entry field that is preserved between a `textDocument/publishDiagnostics`
	// notification and `textDocument/codeAction` request.
	//
	// @since 3.16.0
	Data *json.RawMessage `json:"data,omitempty"`
}

// Client capabilities specific to diagnostic pull requests.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticClientCapabilities
type DiagnosticClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Whether the clients supports related documents for document diagnostic pulls.
	RelatedDocumentSupport bool `json:"relatedDocumentSupport,omitempty"`
	DiagnosticsCapabilities
}

// Diagnostic options.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticOptions
type DiagnosticOptions struct {
	// An optional identifier under which the diagnostics are
	// managed by the client.
	Identifier string `json:"identifier,omitempty"`
	// Whether the language has inter file dependencies meaning that
	// editing code in one file can result in a different diagnostic
	// set in another file. Inter file dependencies are common for
	// most programming languages and typically uncommon for linters.
	InterFileDependencies bool `json:"interFileDependencies"`
	// The server provides support for workspace diagnostics as well.
	WorkspaceDiagnostics bool `json:"workspaceDiagnostics"`
	WorkDoneProgressOptions
}

// Diagnostic registration options.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticRegistrationOptions
type DiagnosticRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DiagnosticOptions
	StaticRegistrationOptions
}

// Represents a related message and source code location for a diagnostic. This should be
// used to point to code locations that cause or related to a diagnostics, e.g when duplicating
// a symbol in a scope.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticRelatedInformation
type DiagnosticRelatedInformation struct {
	// The location of this related diagnostic information.
	Location Location `json:"location"`
	// The message of this related diagnostic information.
	Message string `json:"message"`
}

// Cancellation data returned from a diagnostic request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticServerCancellationData
type DiagnosticServerCancellationData struct {
	RetriggerRequest bool `json:"retriggerRequest"`
}

// The diagnostic's severity.
type DiagnosticSeverity uint32

// The diagnostic tags.
//
// @since 3.15.0
type DiagnosticTag uint32

// Workspace client capabilities specific to diagnostic pull requests.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticWorkspaceClientCapabilities
type DiagnosticWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from
	// the server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// pulled diagnostics currently shown. It should be used with absolute care and
	// is useful for situation where a server for example detects a project wide
	// change that requires such a calculation.
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// General diagnostics capabilities for pull and push model.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#diagnosticsCapabilities
type DiagnosticsCapabilities struct {
	// Whether the clients accepts diagnostics with related information.
	RelatedInformation bool `json:"relatedInformation,omitempty"`
	// Client supports the tag property to provide meta data about a diagnostic.
	// Clients supporting tags have to handle unknown tags gracefully.
	//
	// @since 3.15.0
	TagSupport *ClientDiagnosticsTagOptions `json:"tagSupport,omitempty"`
	// Client supports a codeDescription property
	//
	// @since 3.16.0
	CodeDescriptionSupport bool `json:"codeDescriptionSupport,omitempty"`
	// Whether code action supports the `data` property which is
	// preserved between a `textDocument/publishDiagnostics` and
	// `textDocument/codeAction` request.
	//
	// @since 3.16.0
	DataSupport bool `json:"dataSupport,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeConfigurationClientCapabilities
type DidChangeConfigurationClientCapabilities struct {
	// Did change configuration notification supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// The parameters of a change configuration notification.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeConfigurationParams
type DidChangeConfigurationParams struct {
	// The actual changed settings
	Settings any `json:"settings"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeConfigurationRegistrationOptions
type DidChangeConfigurationRegistrationOptions struct {
	Section *OrPSection_workspace_didChangeConfiguration `json:"section,omitempty"`
}

// The params sent in a change notebook document notification.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeNotebookDocumentParams
type DidChangeNotebookDocumentParams struct {
	// The notebook document that did change. The version number points
	// to the version after all provided changes have been applied. If
	// only the text document content of a cell changes the notebook version
	// doesn't necessarily have to change.
	NotebookDocument VersionedNotebookDocumentIdentifier `json:"notebookDocument"`
	// The actual changes to the notebook document.
	//
	// The changes describe single state changes to the notebook document.
	// So if there are two changes c1 (at array index 0) and c2 (at array
	// index 1) for a notebook in state S then c1 moves the notebook from
	// S to S' and c2 from S' to S''. So c1 is computed on the state S and
	// c2 is computed on the state S'.
	//
	// To mirror the content of a notebook using change events use the following approach:
	//
	//  - start with the same initial content
	//  - apply the 'notebookDocument/didChange' notifications in the order you receive them.
	//  - apply the `NotebookChangeEvent`s in a single notification in the order
	//   you receive them.
	Change NotebookDocumentChangeEvent `json:"change"`
}

// The change text document notification's parameters.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeTextDocumentParams
type DidChangeTextDocumentParams struct {
	// The document that did change. The version number points
	// to the version after all provided content changes have
	// been applied.
	TextDocument VersionedTextDocumentIdentifier `json:"textDocument"`
	// The actual content changes. The content changes describe single state changes
	// to the document. So if there are two content changes c1 (at array index 0) and
	// c2 (at array index 1) for a document in state S then c1 moves the document from
	// S to S' and c2 from S' to S''. So c1 is computed on the state S and c2 is computed
	// on the state S'.
	//
	// To mirror the content of a document using change events use the following approach:
	//
	//  - start with the same initial content
	//  - apply the 'textDocument/didChange' notifications in the order you receive them.
	//  - apply the `TextDocumentContentChangeEvent`s in a single notification in the order
	//   you receive them.
	ContentChanges []TextDocumentContentChangeEvent `json:"contentChanges"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeWatchedFilesClientCapabilities
type DidChangeWatchedFilesClientCapabilities struct {
	// Did change watched files notification supports dynamic registration. Please note
	// that the current protocol doesn't support static configuration for file changes
	// from the server side.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Whether the client has support for {@link  RelativePattern relative pattern}
	// or not.
	//
	// @since 3.17.0
	RelativePatternSupport bool `json:"relativePatternSupport,omitempty"`
}

// The watched files change notification's parameters.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeWatchedFilesParams
type DidChangeWatchedFilesParams struct {
	// The actual file events.
	Changes []FileEvent `json:"changes"`
}

// Describe options to be used when registered for text document change events.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeWatchedFilesRegistrationOptions
type DidChangeWatchedFilesRegistrationOptions struct {
	// The watchers to register.
	Watchers []FileSystemWatcher `json:"watchers"`
}

// The parameters of a `workspace/didChangeWorkspaceFolders` notification.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didChangeWorkspaceFoldersParams
type DidChangeWorkspaceFoldersParams struct {
	// The actual workspace folder change event.
	Event WorkspaceFoldersChangeEvent `json:"event"`
}

// The params sent in a close notebook document notification.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didCloseNotebookDocumentParams
type DidCloseNotebookDocumentParams struct {
	// The notebook document that got closed.
	NotebookDocument NotebookDocumentIdentifier `json:"notebookDocument"`
	// The text documents that represent the content
	// of a notebook cell that got closed.
	CellTextDocuments []TextDocumentIdentifier `json:"cellTextDocuments"`
}

// The parameters sent in a close text document notification
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didCloseTextDocumentParams
type DidCloseTextDocumentParams struct {
	// The document that was closed.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
}

// The params sent in an open notebook document notification.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didOpenNotebookDocumentParams
type DidOpenNotebookDocumentParams struct {
	// The notebook document that got opened.
	NotebookDocument NotebookDocument `json:"notebookDocument"`
	// The text documents that represent the content
	// of a notebook cell.
	CellTextDocuments []TextDocumentItem `json:"cellTextDocuments"`
}

// The parameters sent in an open text document notification
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didOpenTextDocumentParams
type DidOpenTextDocumentParams struct {
	// The document that was opened.
	TextDocument TextDocumentItem `json:"textDocument"`
}

// The params sent in a save notebook document notification.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didSaveNotebookDocumentParams
type DidSaveNotebookDocumentParams struct {
	// The notebook document that got saved.
	NotebookDocument NotebookDocumentIdentifier `json:"notebookDocument"`
}

// The parameters sent in a save text document notification
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#didSaveTextDocumentParams
type DidSaveTextDocumentParams struct {
	// The document that was saved.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// Optional the content when saved. Depends on the includeText value
	// when the save notification was requested.
	Text *string `json:"text,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentColorClientCapabilities
type DocumentColorClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `DocumentColorRegistrationOptions` return value
	// for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentColorOptions
type DocumentColorOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link DocumentColorRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentColorParams
type DocumentColorParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentColorRegistrationOptions
type DocumentColorRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentColorOptions
	StaticRegistrationOptions
}

// Parameters of the document diagnostic request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentDiagnosticParams
type DocumentDiagnosticParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The additional identifier  provided during registration.
	Identifier string `json:"identifier,omitempty"`
	// The result id of a previous response if provided.
	PreviousResultID string `json:"previousResultId,omitempty"`
	WorkDoneProgressParams
	PartialResultParams
}

// The result of a document diagnostic pull request. A report can
// either be a full report containing all diagnostics for the
// requested document or an unchanged report indicating that nothing
// has changed in terms of diagnostics in comparison to the last
// pull request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentDiagnosticReport
type DocumentDiagnosticReport = Or_DocumentDiagnosticReport // (alias)
// The document diagnostic report kinds.
//
// @since 3.17.0
type DocumentDiagnosticReportKind string

// A partial result for a document diagnostic report.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentDiagnosticReportPartialResult
type DocumentDiagnosticReportPartialResult struct {
	RelatedDocuments map[DocumentURI]any `json:"relatedDocuments"`
}

// A document filter describes a top level text document or
// a notebook cell document.
//
// @since 3.17.0 - support for NotebookCellTextDocumentFilter.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentFilter
type DocumentFilter = Or_DocumentFilter // (alias)
// Client capabilities of a {@link DocumentFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentFormattingClientCapabilities
type DocumentFormattingClientCapabilities struct {
	// Whether formatting supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Provider options for a {@link DocumentFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentFormattingOptions
type DocumentFormattingOptions struct {
	WorkDoneProgressOptions
}

// The parameters of a {@link DocumentFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentFormattingParams
type DocumentFormattingParams struct {
	// The document to format.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The format options.
	Options FormattingOptions `json:"options"`
	WorkDoneProgressParams
}

// Registration options for a {@link DocumentFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentFormattingRegistrationOptions
type DocumentFormattingRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentFormattingOptions
}

// A document highlight is a range inside a text document which deserves
// special attention. Usually a document highlight is visualized by changing
// the background color of its range.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentHighlight
type DocumentHighlight struct {
	// The range this highlight applies to.
	Range Range `json:"range"`
	// The highlight kind, default is {@link DocumentHighlightKind.Text text}.
	Kind DocumentHighlightKind `json:"kind,omitempty"`
}

// Client Capabilities for a {@link DocumentHighlightRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentHighlightClientCapabilities
type DocumentHighlightClientCapabilities struct {
	// Whether document highlight supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// A document highlight kind.
type DocumentHighlightKind uint32

// Provider options for a {@link DocumentHighlightRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentHighlightOptions
type DocumentHighlightOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link DocumentHighlightRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentHighlightParams
type DocumentHighlightParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link DocumentHighlightRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentHighlightRegistrationOptions
type DocumentHighlightRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentHighlightOptions
}

// A document link is a range in a text document that links to an internal or external resource, like another
// text document or a web site.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLink
type DocumentLink struct {
	// The range this link applies to.
	Range Range `json:"range"`
	// The uri this link points to. If missing a resolve request is sent later.
	Target *URI `json:"target,omitempty"`
	// The tooltip text when you hover over this link.
	//
	// If a tooltip is provided, is will be displayed in a string that includes instructions on how to
	// trigger the link, such as `{0} (ctrl + click)`. The specific instructions vary depending on OS,
	// user settings, and localization.
	//
	// @since 3.15.0
	Tooltip string `json:"tooltip,omitempty"`
	// A data entry field that is preserved on a document link between a
	// DocumentLinkRequest and a DocumentLinkResolveRequest.
	Data any `json:"data,omitempty"`
}

// The client capabilities of a {@link DocumentLinkRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLinkClientCapabilities
type DocumentLinkClientCapabilities struct {
	// Whether document link supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Whether the client supports the `tooltip` property on `DocumentLink`.
	//
	// @since 3.15.0
	TooltipSupport bool `json:"tooltipSupport,omitempty"`
}

// Provider options for a {@link DocumentLinkRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLinkOptions
type DocumentLinkOptions struct {
	// Document links have a resolve provider as well.
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link DocumentLinkRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLinkParams
type DocumentLinkParams struct {
	// The document to provide document links for.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link DocumentLinkRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLinkRegistrationOptions
type DocumentLinkRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentLinkOptions
}

// Client capabilities of a {@link DocumentOnTypeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentOnTypeFormattingClientCapabilities
type DocumentOnTypeFormattingClientCapabilities struct {
	// Whether on type formatting supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Provider options for a {@link DocumentOnTypeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentOnTypeFormattingOptions
type DocumentOnTypeFormattingOptions struct {
	// A character on which formatting should be triggered, like `{`.
	FirstTriggerCharacter string `json:"firstTriggerCharacter"`
	// More trigger characters.
	MoreTriggerCharacter []string `json:"moreTriggerCharacter,omitempty"`
}

// The parameters of a {@link DocumentOnTypeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentOnTypeFormattingParams
type DocumentOnTypeFormattingParams struct {
	// The document to format.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The position around which the on type formatting should happen.
	// This is not necessarily the exact position where the character denoted
	// by the property `ch` got typed.
	Position Position `json:"position"`
	// The character that has been typed that triggered the formatting
	// on type request. That is not necessarily the last character that
	// got inserted into the document since the client could auto insert
	// characters as well (e.g. like automatic brace completion).
	Ch string `json:"ch"`
	// The formatting options.
	Options FormattingOptions `json:"options"`
}

// Registration options for a {@link DocumentOnTypeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentOnTypeFormattingRegistrationOptions
type DocumentOnTypeFormattingRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentOnTypeFormattingOptions
}

// Client capabilities of a {@link DocumentRangeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentRangeFormattingClientCapabilities
type DocumentRangeFormattingClientCapabilities struct {
	// Whether range formatting supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Whether the client supports formatting multiple ranges at once.
	//
	// @since 3.18.0
	// @proposed
	RangesSupport bool `json:"rangesSupport,omitempty"`
}

// Provider options for a {@link DocumentRangeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentRangeFormattingOptions
type DocumentRangeFormattingOptions struct {
	// Whether the server supports formatting multiple ranges at once.
	//
	// @since 3.18.0
	// @proposed
	RangesSupport bool `json:"rangesSupport,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link DocumentRangeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentRangeFormattingParams
type DocumentRangeFormattingParams struct {
	// The document to format.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The range to format
	Range Range `json:"range"`
	// The format options
	Options FormattingOptions `json:"options"`
	WorkDoneProgressParams
}

// Registration options for a {@link DocumentRangeFormattingRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentRangeFormattingRegistrationOptions
type DocumentRangeFormattingRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentRangeFormattingOptions
}

// The parameters of a {@link DocumentRangesFormattingRequest}.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentRangesFormattingParams
type DocumentRangesFormattingParams struct {
	// The document to format.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The ranges to format
	Ranges []Range `json:"ranges"`
	// The format options
	Options FormattingOptions `json:"options"`
	WorkDoneProgressParams
}

// A document selector is the combination of one or many document filters.
//
// @sample `let sel:DocumentSelector = [{ language: 'typescript' }, { language: 'json', pattern: '**∕tsconfig.json' }]`;
//
// The use of a string as a document filter is deprecated @since 3.16.0.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSelector
type DocumentSelector = []DocumentFilter // (alias)
// Represents programming constructs like variables, classes, interfaces etc.
// that appear in a document. Document symbols can be hierarchical and they
// have two ranges: one that encloses its definition and one that points to
// its most interesting range, e.g. the range of an identifier.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbol
type DocumentSymbol struct {
	// The name of this symbol. Will be displayed in the user interface and therefore must not be
	// an empty string or a string only consisting of white spaces.
	Name string `json:"name"`
	// More detail for this symbol, e.g the signature of a function.
	Detail string `json:"detail,omitempty"`
	// The kind of this symbol.
	Kind SymbolKind `json:"kind"`
	// Tags for this document symbol.
	//
	// @since 3.16.0
	Tags []SymbolTag `json:"tags,omitempty"`
	// Indicates if this symbol is deprecated.
	//
	// @deprecated Use tags instead
	Deprecated bool `json:"deprecated,omitempty"`
	// The range enclosing this symbol not including leading/trailing whitespace but everything else
	// like comments. This information is typically used to determine if the clients cursor is
	// inside the symbol to reveal in the symbol in the UI.
	Range Range `json:"range"`
	// The range that should be selected and revealed when this symbol is being picked, e.g the name of a function.
	// Must be contained by the `range`.
	SelectionRange Range `json:"selectionRange"`
	// Children of this symbol, e.g. properties of a class.
	Children []DocumentSymbol `json:"children,omitempty"`
}

// Client Capabilities for a {@link DocumentSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbolClientCapabilities
type DocumentSymbolClientCapabilities struct {
	// Whether document symbol supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Specific capabilities for the `SymbolKind` in the
	// `textDocument/documentSymbol` request.
	SymbolKind *ClientSymbolKindOptions `json:"symbolKind,omitempty"`
	// The client supports hierarchical document symbols.
	HierarchicalDocumentSymbolSupport bool `json:"hierarchicalDocumentSymbolSupport,omitempty"`
	// The client supports tags on `SymbolInformation`. Tags are supported on
	// `DocumentSymbol` if `hierarchicalDocumentSymbolSupport` is set to true.
	// Clients supporting tags have to handle unknown tags gracefully.
	//
	// @since 3.16.0
	TagSupport *ClientSymbolTagOptions `json:"tagSupport,omitempty"`
	// The client supports an additional label presented in the UI when
	// registering a document symbol provider.
	//
	// @since 3.16.0
	LabelSupport bool `json:"labelSupport,omitempty"`
}

// Provider options for a {@link DocumentSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbolOptions
type DocumentSymbolOptions struct {
	// A human-readable string that is shown when multiple outlines trees
	// are shown for the same document.
	//
	// @since 3.16.0
	Label string `json:"label,omitempty"`
	WorkDoneProgressOptions
}

// Parameters for a {@link DocumentSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbolParams
type DocumentSymbolParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link DocumentSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentSymbolRegistrationOptions
type DocumentSymbolRegistrationOptions struct {
	TextDocumentRegistrationOptions
	DocumentSymbolOptions
}

// Edit range variant that includes ranges for insert and replace operations.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#editRangeWithInsertReplace
type EditRangeWithInsertReplace struct {
	Insert  Range `json:"insert"`
	Replace Range `json:"replace"`
}

// Predefined error codes.
type ErrorCodes int32

// The client capabilities of a {@link ExecuteCommandRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#executeCommandClientCapabilities
type ExecuteCommandClientCapabilities struct {
	// Execute command supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// The server capabilities of a {@link ExecuteCommandRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#executeCommandOptions
type ExecuteCommandOptions struct {
	// The commands to be executed on the server
	Commands []string `json:"commands"`
	WorkDoneProgressOptions
}

// The parameters of a {@link ExecuteCommandRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#executeCommandParams
type ExecuteCommandParams struct {
	// The identifier of the actual command handler.
	Command string `json:"command"`
	// Arguments that the command should be invoked with.
	Arguments []json.RawMessage `json:"arguments,omitempty"`

	// Support interactive command execution.
	//
	// Note: This is a non-standard protocol extension. See golang/go#76331.
	InteractiveParams
	WorkDoneProgressParams
}

// Registration options for a {@link ExecuteCommandRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#executeCommandRegistrationOptions
type ExecuteCommandRegistrationOptions struct {
	ExecuteCommandOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#executionSummary
type ExecutionSummary struct {
	// A strict monotonically increasing value
	// indicating the execution order of a cell
	// inside a notebook.
	ExecutionOrder uint32 `json:"executionOrder"`
	// Whether the execution was successful or
	// not if known by the client.
	Success bool `json:"success,omitempty"`
}
type FailureHandlingKind string

// The file event type
type FileChangeType uint32

// Represents information on a file/folder create.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileCreate
type FileCreate struct {
	// A file:// URI for the location of the file/folder being created.
	URI string `json:"uri"`
}

// Represents information on a file/folder delete.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileDelete
type FileDelete struct {
	// A file:// URI for the location of the file/folder being deleted.
	URI string `json:"uri"`
}

// An event describing a file change.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileEvent
type FileEvent struct {
	// The file's uri.
	URI DocumentURI `json:"uri"`
	// The change type.
	Type FileChangeType `json:"type"`
}

// Capabilities relating to events from file operations by the user in the client.
//
// These events do not come from the file system, they come from user operations
// like renaming a file in the UI.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationClientCapabilities
type FileOperationClientCapabilities struct {
	// Whether the client supports dynamic registration for file requests/notifications.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client has support for sending didCreateFiles notifications.
	DidCreate bool `json:"didCreate,omitempty"`
	// The client has support for sending willCreateFiles requests.
	WillCreate bool `json:"willCreate,omitempty"`
	// The client has support for sending didRenameFiles notifications.
	DidRename bool `json:"didRename,omitempty"`
	// The client has support for sending willRenameFiles requests.
	WillRename bool `json:"willRename,omitempty"`
	// The client has support for sending didDeleteFiles notifications.
	DidDelete bool `json:"didDelete,omitempty"`
	// The client has support for sending willDeleteFiles requests.
	WillDelete bool `json:"willDelete,omitempty"`
}

// A filter to describe in which file operation requests or notifications
// the server is interested in receiving.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationFilter
type FileOperationFilter struct {
	// A Uri scheme like `file` or `untitled`.
	Scheme string `json:"scheme,omitempty"`
	// The actual file operation pattern.
	Pattern FileOperationPattern `json:"pattern"`
}

// Options for notifications/requests for user operations on files.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationOptions
type FileOperationOptions struct {
	// The server is interested in receiving didCreateFiles notifications.
	DidCreate *FileOperationRegistrationOptions `json:"didCreate,omitempty"`
	// The server is interested in receiving willCreateFiles requests.
	WillCreate *FileOperationRegistrationOptions `json:"willCreate,omitempty"`
	// The server is interested in receiving didRenameFiles notifications.
	DidRename *FileOperationRegistrationOptions `json:"didRename,omitempty"`
	// The server is interested in receiving willRenameFiles requests.
	WillRename *FileOperationRegistrationOptions `json:"willRename,omitempty"`
	// The server is interested in receiving didDeleteFiles file notifications.
	DidDelete *FileOperationRegistrationOptions `json:"didDelete,omitempty"`
	// The server is interested in receiving willDeleteFiles file requests.
	WillDelete *FileOperationRegistrationOptions `json:"willDelete,omitempty"`
}

// A pattern to describe in which file operation requests or notifications
// the server is interested in receiving.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationPattern
type FileOperationPattern struct {
	// The glob pattern to match. Glob patterns can have the following syntax:
	//
	//  - `*` to match one or more characters in a path segment
	//  - `?` to match on one character in a path segment
	//  - `**` to match any number of path segments, including none
	//  - `{}` to group sub patterns into an OR expression. (e.g. `**​/*.{ts,js}` matches all TypeScript and JavaScript files)
	//  - `[]` to declare a range of characters to match in a path segment (e.g., `example.[0-9]` to match on `example.0`, `example.1`, …)
	//  - `[!...]` to negate a range of characters to match in a path segment (e.g., `example.[!0-9]` to match on `example.a`, `example.b`, but not `example.0`)
	Glob string `json:"glob"`
	// Whether to match files or folders with this pattern.
	//
	// Matches both if undefined.
	Matches *FileOperationPatternKind `json:"matches,omitempty"`
	// Additional options used during matching.
	Options *FileOperationPatternOptions `json:"options,omitempty"`
}

// A pattern kind describing if a glob pattern matches a file a folder or
// both.
//
// @since 3.16.0
type FileOperationPatternKind string

// Matching options for the file operation pattern.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationPatternOptions
type FileOperationPatternOptions struct {
	// The pattern should be matched ignoring casing.
	IgnoreCase bool `json:"ignoreCase,omitempty"`
}

// The options to register for file operations.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileOperationRegistrationOptions
type FileOperationRegistrationOptions struct {
	// The actual filters.
	Filters []FileOperationFilter `json:"filters"`
}

// Represents information on a file/folder rename.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileRename
type FileRename struct {
	// A file:// URI for the original location of the file/folder being renamed.
	OldURI string `json:"oldUri"`
	// A file:// URI for the new location of the file/folder being renamed.
	NewURI string `json:"newUri"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fileSystemWatcher
type FileSystemWatcher struct {
	// The glob pattern to watch. See {@link GlobPattern glob pattern} for more detail.
	//
	// @since 3.17.0 support for relative patterns.
	GlobPattern GlobPattern `json:"globPattern"`
	// The kind of events of interest. If omitted it defaults
	// to WatchKind.Create | WatchKind.Change | WatchKind.Delete
	// which is 7.
	Kind *WatchKind `json:"kind,omitempty"`
}

// Represents a folding range. To be valid, start and end line must be bigger than zero and smaller
// than the number of lines in the document. Clients are free to ignore invalid ranges.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRange
type FoldingRange struct {
	// The zero-based start line of the range to fold. The folded area starts after the line's last character.
	// To be valid, the end must be zero or larger and smaller than the number of lines in the document.
	StartLine *uint32 `json:"startLine,omitempty"`
	// The zero-based character offset from where the folded range starts. If not defined, defaults to the length of the start line.
	StartCharacter *uint32 `json:"startCharacter,omitempty"`
	// The zero-based end line of the range to fold. The folded area ends with the line's last character.
	// To be valid, the end must be zero or larger and smaller than the number of lines in the document.
	EndLine *uint32 `json:"endLine,omitempty"`
	// The zero-based character offset before the folded range ends. If not defined, defaults to the length of the end line.
	EndCharacter *uint32 `json:"endCharacter,omitempty"`
	// Describes the kind of the folding range such as 'comment' or 'region'. The kind
	// is used to categorize folding ranges and used by commands like 'Fold all comments'.
	// See {@link FoldingRangeKind} for an enumeration of standardized kinds.
	Kind string `json:"kind,omitempty"`
	// The text that the client should show when the specified range is
	// collapsed. If not defined or not supported by the client, a default
	// will be chosen by the client.
	//
	// @since 3.17.0
	CollapsedText string `json:"collapsedText,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRangeClientCapabilities
type FoldingRangeClientCapabilities struct {
	// Whether implementation supports dynamic registration for folding range
	// providers. If this is set to `true` the client supports the new
	// `FoldingRangeRegistrationOptions` return value for the corresponding
	// server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The maximum number of folding ranges that the client prefers to receive
	// per document. The value serves as a hint, servers are free to follow the
	// limit.
	RangeLimit uint32 `json:"rangeLimit"`
	// If set, the client signals that it only supports folding complete lines.
	// If set, client will ignore specified `startCharacter` and `endCharacter`
	// properties in a FoldingRange.
	LineFoldingOnly bool `json:"lineFoldingOnly,omitempty"`
	// Specific options for the folding range kind.
	//
	// @since 3.17.0
	FoldingRangeKind *ClientFoldingRangeKindOptions `json:"foldingRangeKind,omitempty"`
	// Specific options for the folding range.
	//
	// @since 3.17.0
	FoldingRange *ClientFoldingRangeOptions `json:"foldingRange,omitempty"`
}

// A set of predefined range kinds.
type FoldingRangeKind string

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRangeOptions
type FoldingRangeOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link FoldingRangeRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRangeParams
type FoldingRangeParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRangeRegistrationOptions
type FoldingRangeRegistrationOptions struct {
	TextDocumentRegistrationOptions
	FoldingRangeOptions
	StaticRegistrationOptions
}

// Client workspace capabilities specific to folding ranges
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#foldingRangeWorkspaceClientCapabilities
type FoldingRangeWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from the
	// server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// folding ranges currently shown. It should be used with absolute care and is
	// useful for situation where a server for example detects a project wide
	// change that requires such a calculation.
	//
	// @since 3.18.0
	// @proposed
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// Value-object describing what options formatting should use.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#formattingOptions
type FormattingOptions struct {
	// Size of a tab in spaces.
	TabSize uint32 `json:"tabSize"`
	// Prefer spaces over tabs.
	InsertSpaces bool `json:"insertSpaces"`
	// Trim trailing whitespace on a line.
	//
	// @since 3.15.0
	TrimTrailingWhitespace bool `json:"trimTrailingWhitespace,omitempty"`
	// Insert a newline character at the end of the file if one does not exist.
	//
	// @since 3.15.0
	InsertFinalNewline bool `json:"insertFinalNewline,omitempty"`
	// Trim all newlines after the final newline at the end of the file.
	//
	// @since 3.15.0
	TrimFinalNewlines bool `json:"trimFinalNewlines,omitempty"`
}

// A diagnostic report with a full set of problems.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#fullDocumentDiagnosticReport
type FullDocumentDiagnosticReport struct {
	// A full document diagnostic report.
	Kind string `json:"kind"`
	// An optional result id. If provided it will
	// be sent on the next diagnostic request for the
	// same document.
	ResultID string `json:"resultId,omitempty"`
	// The actual items.
	Items []Diagnostic `json:"items"`
}

// General client capabilities.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#generalClientCapabilities
type GeneralClientCapabilities struct {
	// Client capability that signals how the client
	// handles stale requests (e.g. a request
	// for which the client will not process the response
	// anymore since the information is outdated).
	//
	// @since 3.17.0
	StaleRequestSupport *StaleRequestSupportOptions `json:"staleRequestSupport,omitempty"`
	// Client capabilities specific to regular expressions.
	//
	// @since 3.16.0
	RegularExpressions *RegularExpressionsClientCapabilities `json:"regularExpressions,omitempty"`
	// Client capabilities specific to the client's markdown parser.
	//
	// @since 3.16.0
	Markdown *MarkdownClientCapabilities `json:"markdown,omitempty"`
	// The position encodings supported by the client. Client and server
	// have to agree on the same position encoding to ensure that offsets
	// (e.g. character position in a line) are interpreted the same on both
	// sides.
	//
	// To keep the protocol backwards compatible the following applies: if
	// the value 'utf-16' is missing from the array of position encodings
	// servers can assume that the client supports UTF-16. UTF-16 is
	// therefore a mandatory encoding.
	//
	// If omitted it defaults to ['utf-16'].
	//
	// Implementation considerations: since the conversion from one encoding
	// into another requires the content of the file / line the conversion
	// is best done where the file is read which is usually on the server
	// side.
	//
	// @since 3.17.0
	PositionEncodings []PositionEncodingKind `json:"positionEncodings,omitempty"`
}

// The glob pattern. Either a string pattern or a relative pattern.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#globPattern
type GlobPattern = Or_GlobPattern // (alias)
// The result of a hover request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#hover
type Hover struct {
	// The hover's content
	Contents MarkupContent `json:"contents"`
	// An optional range inside the text document that is used to
	// visualize the hover, e.g. by changing the background color.
	Range Range `json:"range,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#hoverClientCapabilities
type HoverClientCapabilities struct {
	// Whether hover supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Client supports the following content formats for the content
	// property. The order describes the preferred format of the client.
	ContentFormat []MarkupKind `json:"contentFormat,omitempty"`
}

// Hover options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#hoverOptions
type HoverOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link HoverRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#hoverParams
type HoverParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Registration options for a {@link HoverRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#hoverRegistrationOptions
type HoverRegistrationOptions struct {
	TextDocumentRegistrationOptions
	HoverOptions
}

// @since 3.6.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#implementationClientCapabilities
type ImplementationClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `ImplementationRegistrationOptions` return value
	// for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports additional metadata in the form of definition links.
	//
	// @since 3.14.0
	LinkSupport bool `json:"linkSupport,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#implementationOptions
type ImplementationOptions struct {
	WorkDoneProgressOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#implementationParams
type ImplementationParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#implementationRegistrationOptions
type ImplementationRegistrationOptions struct {
	TextDocumentRegistrationOptions
	ImplementationOptions
	StaticRegistrationOptions
}

// The data type of the ResponseError if the
// initialize request fails.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initializeError
type InitializeError struct {
	// Indicates whether the client execute the following retry logic:
	// (1) show the message provided by the ResponseError to the user
	// (2) user selects retry or cancel
	// (3) if user selected retry the initialize method is sent again.
	Retry bool `json:"retry"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initializeParams
type InitializeParams struct {
	XInitializeParams
	WorkspaceFoldersInitializeParams
}

// The result returned from an initialize request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initializeResult
type InitializeResult struct {
	// The capabilities the language server provides.
	Capabilities ServerCapabilities `json:"capabilities"`
	// Information about the server.
	//
	// @since 3.15.0
	ServerInfo *ServerInfo `json:"serverInfo,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initializedParams
type InitializedParams struct {
}

// Inlay hint information.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHint
type InlayHint struct {
	// The position of this hint.
	//
	// If multiple hints have the same position, they will be shown in the order
	// they appear in the response.
	Position Position `json:"position"`
	// The label of this hint. A human readable string or an array of
	// InlayHintLabelPart label parts.
	//
	// *Note* that neither the string nor the label part can be empty.
	Label []InlayHintLabelPart `json:"label"`
	// The kind of this hint. Can be omitted in which case the client
	// should fall back to a reasonable default.
	Kind InlayHintKind `json:"kind,omitempty"`
	// Optional text edits that are performed when accepting this inlay hint.
	//
	// *Note* that edits are expected to change the document so that the inlay
	// hint (or its nearest variant) is now part of the document and the inlay
	// hint itself is now obsolete.
	TextEdits []TextEdit `json:"textEdits,omitempty"`
	// The tooltip text when you hover over this item.
	Tooltip *OrPTooltip_textDocument_inlayHint `json:"tooltip,omitempty"`
	// Render padding before the hint.
	//
	// Note: Padding should use the editor's background color, not the
	// background color of the hint itself. That means padding can be used
	// to visually align/separate an inlay hint.
	PaddingLeft bool `json:"paddingLeft,omitempty"`
	// Render padding after the hint.
	//
	// Note: Padding should use the editor's background color, not the
	// background color of the hint itself. That means padding can be used
	// to visually align/separate an inlay hint.
	PaddingRight bool `json:"paddingRight,omitempty"`
	// A data entry field that is preserved on an inlay hint between
	// a `textDocument/inlayHint` and a `inlayHint/resolve` request.
	Data any `json:"data,omitempty"`
}

// Inlay hint client capabilities.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintClientCapabilities
type InlayHintClientCapabilities struct {
	// Whether inlay hints support dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Indicates which properties a client can resolve lazily on an inlay
	// hint.
	ResolveSupport *ClientInlayHintResolveOptions `json:"resolveSupport,omitempty"`
}

// Inlay hint kinds.
//
// @since 3.17.0
type InlayHintKind uint32

// An inlay hint label part allows for interactive and composite labels
// of inlay hints.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintLabelPart
type InlayHintLabelPart struct {
	// The value of this label part.
	Value string `json:"value"`
	// The tooltip text when you hover over this label part. Depending on
	// the client capability `inlayHint.resolveSupport` clients might resolve
	// this property late using the resolve request.
	Tooltip *OrPTooltipPLabel `json:"tooltip,omitempty"`
	// An optional source code location that represents this
	// label part.
	//
	// The editor will use this location for the hover and for code navigation
	// features: This part will become a clickable link that resolves to the
	// definition of the symbol at the given location (not necessarily the
	// location itself), it shows the hover that shows at the given location,
	// and it shows a context menu with further code navigation commands.
	//
	// Depending on the client capability `inlayHint.resolveSupport` clients
	// might resolve this property late using the resolve request.
	Location *Location `json:"location,omitempty"`
	// An optional command for this label part.
	//
	// Depending on the client capability `inlayHint.resolveSupport` clients
	// might resolve this property late using the resolve request.
	Command *Command `json:"command,omitempty"`
}

// Inlay hint options used during static registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintOptions
type InlayHintOptions struct {
	// The server provides support to resolve additional
	// information for an inlay hint item.
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	WorkDoneProgressOptions
}

// A parameter literal used in inlay hint requests.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintParams
type InlayHintParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The document range for which inlay hints should be computed.
	Range Range `json:"range"`
	WorkDoneProgressParams
}

// Inlay hint options used during static or dynamic registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintRegistrationOptions
type InlayHintRegistrationOptions struct {
	InlayHintOptions
	TextDocumentRegistrationOptions
	StaticRegistrationOptions
}

// Client workspace capabilities specific to inlay hints.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHintWorkspaceClientCapabilities
type InlayHintWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from
	// the server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// inlay hints currently shown. It should be used with absolute care and
	// is useful for situation where a server for example detects a project wide
	// change that requires such a calculation.
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// Client capabilities specific to inline completions.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionClientCapabilities
type InlineCompletionClientCapabilities struct {
	// Whether implementation supports dynamic registration for inline completion providers.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Provides information about the context in which an inline completion was requested.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionContext
type InlineCompletionContext struct {
	// Describes how the inline completion was triggered.
	TriggerKind InlineCompletionTriggerKind `json:"triggerKind"`
	// Provides information about the currently selected item in the autocomplete widget if it is visible.
	SelectedCompletionInfo *SelectedCompletionInfo `json:"selectedCompletionInfo,omitempty"`
}

// An inline completion item represents a text snippet that is proposed inline to complete text that is being typed.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionItem
type InlineCompletionItem struct {
	// The text to replace the range with. Must be set.
	InsertText Or_InlineCompletionItem_insertText `json:"insertText"`
	// A text that is used to decide if this inline completion should be shown. When `falsy` the {@link InlineCompletionItem.insertText} is used.
	FilterText string `json:"filterText,omitempty"`
	// The range to replace. Must begin and end on the same line.
	Range *Range `json:"range,omitempty"`
	// An optional {@link Command} that is executed *after* inserting this completion.
	Command *Command `json:"command,omitempty"`
}

// Represents a collection of {@link InlineCompletionItem inline completion items} to be presented in the editor.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionList
type InlineCompletionList struct {
	// The inline completion items
	Items []InlineCompletionItem `json:"items"`
}

// Inline completion options used during static registration.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionOptions
type InlineCompletionOptions struct {
	WorkDoneProgressOptions
}

// A parameter literal used in inline completion requests.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionParams
type InlineCompletionParams struct {
	// Additional information about the context in which inline completions were
	// requested.
	Context InlineCompletionContext `json:"context"`
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Inline completion options used during static or dynamic registration.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineCompletionRegistrationOptions
type InlineCompletionRegistrationOptions struct {
	InlineCompletionOptions
	TextDocumentRegistrationOptions
	StaticRegistrationOptions
}

// Describes how an {@link InlineCompletionItemProvider inline completion provider} was triggered.
//
// @since 3.18.0
// @proposed
type InlineCompletionTriggerKind uint32

// Inline value information can be provided by different means:
//
//   - directly as a text value (class InlineValueText).
//   - as a name to use for a variable lookup (class InlineValueVariableLookup)
//   - as an evaluatable expression (class InlineValueEvaluatableExpression)
//
// The InlineValue types combines all inline value types into one type.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValue
type InlineValue = Or_InlineValue // (alias)
// Client capabilities specific to inline values.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueClientCapabilities
type InlineValueClientCapabilities struct {
	// Whether implementation supports dynamic registration for inline value providers.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueContext
type InlineValueContext struct {
	// The stack frame (as a DAP Id) where the execution has stopped.
	FrameID int32 `json:"frameId"`
	// The document range where execution has stopped.
	// Typically the end position of the range denotes the line where the inline values are shown.
	StoppedLocation Range `json:"stoppedLocation"`
}

// Provide an inline value through an expression evaluation.
// If only a range is specified, the expression will be extracted from the underlying document.
// An optional expression can be used to override the extracted expression.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueEvaluatableExpression
type InlineValueEvaluatableExpression struct {
	// The document range for which the inline value applies.
	// The range is used to extract the evaluatable expression from the underlying document.
	Range Range `json:"range"`
	// If specified the expression overrides the extracted expression.
	Expression string `json:"expression,omitempty"`
}

// Inline value options used during static registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueOptions
type InlineValueOptions struct {
	WorkDoneProgressOptions
}

// A parameter literal used in inline value requests.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueParams
type InlineValueParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The document range for which inline values should be computed.
	Range Range `json:"range"`
	// Additional information about the context in which inline values were
	// requested.
	Context InlineValueContext `json:"context"`
	WorkDoneProgressParams
}

// Inline value options used during static or dynamic registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueRegistrationOptions
type InlineValueRegistrationOptions struct {
	InlineValueOptions
	TextDocumentRegistrationOptions
	StaticRegistrationOptions
}

// Provide inline value as text.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueText
type InlineValueText struct {
	// The document range for which the inline value applies.
	Range Range `json:"range"`
	// The text of the inline value.
	Text string `json:"text"`
}

// Provide inline value through a variable lookup.
// If only a range is specified, the variable name will be extracted from the underlying document.
// An optional variable name can be used to override the extracted name.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueVariableLookup
type InlineValueVariableLookup struct {
	// The document range for which the inline value applies.
	// The range is used to extract the variable name from the underlying document.
	Range Range `json:"range"`
	// If specified the name of the variable to look up.
	VariableName string `json:"variableName,omitempty"`
	// How to perform the lookup.
	CaseSensitiveLookup bool `json:"caseSensitiveLookup"`
}

// Client workspace capabilities specific to inline values.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlineValueWorkspaceClientCapabilities
type InlineValueWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from the
	// server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// inline values currently shown. It should be used with absolute care and is
	// useful for situation where a server for example detects a project wide
	// change that requires such a calculation.
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// A special text edit to provide an insert and a replace operation.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#insertReplaceEdit
type InsertReplaceEdit struct {
	// The string to be inserted.
	NewText string `json:"newText"`
	// The range if the insert is requested
	Insert Range `json:"insert"`
	// The range if the replace is requested.
	Replace Range `json:"replace"`
}

// Defines whether the insert text in a completion item should be interpreted as
// plain text or a snippet.
type InsertTextFormat uint32

// How whitespace and indentation is handled during completion
// item insertion.
//
// @since 3.16.0
type InsertTextMode uint32
type LSPAny = any

// LSP arrays.
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#lSPArray
type LSPArray = []any // (alias)
type LSPErrorCodes int32

// LSP object definition.
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#lSPObject
type LSPObject = map[string]LSPAny // (alias)
// Predefined Language kinds
// @since 3.18.0
type LanguageKind string

// Client capabilities for the linked editing range request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#linkedEditingRangeClientCapabilities
type LinkedEditingRangeClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#linkedEditingRangeOptions
type LinkedEditingRangeOptions struct {
	WorkDoneProgressOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#linkedEditingRangeParams
type LinkedEditingRangeParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#linkedEditingRangeRegistrationOptions
type LinkedEditingRangeRegistrationOptions struct {
	TextDocumentRegistrationOptions
	LinkedEditingRangeOptions
	StaticRegistrationOptions
}

// The result of a linked editing range request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#linkedEditingRanges
type LinkedEditingRanges struct {
	// A list of ranges that can be edited together. The ranges must have
	// identical length and contain identical text content. The ranges cannot overlap.
	Ranges []Range `json:"ranges"`
	// An optional word pattern (regular expression) that describes valid contents for
	// the given ranges. If no pattern is provided, the client configuration's word
	// pattern will be used.
	WordPattern string `json:"wordPattern,omitempty"`
}

// created for Literal (Lit_ClientSemanticTokensRequestOptions_range_Item1)
type Lit_ClientSemanticTokensRequestOptions_range_Item1 struct {
}

// Represents a location inside a resource, such as a line
// inside a text file.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#location
type Location struct {
	URI   DocumentURI `json:"uri"`
	Range Range       `json:"range"`
}

// Represents the connection of two locations. Provides additional metadata over normal {@link Location locations},
// including an origin range.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#locationLink
type LocationLink struct {
	// Span of the origin of this link.
	//
	// Used as the underlined span for mouse interaction. Defaults to the word range at
	// the definition position.
	OriginSelectionRange *Range `json:"originSelectionRange,omitempty"`
	// The target resource identifier of this link.
	TargetURI DocumentURI `json:"targetUri"`
	// The full target range of this link. If the target for example is a symbol then target range is the
	// range enclosing this symbol not including leading/trailing whitespace but everything else
	// like comments. This information is typically used to highlight the range in the editor.
	TargetRange Range `json:"targetRange"`
	// The range that should be selected and revealed when this link is being followed, e.g the name of a function.
	// Must be contained by the `targetRange`. See also `DocumentSymbol#range`
	TargetSelectionRange Range `json:"targetSelectionRange"`
}

// Location with only uri and does not include range.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#locationUriOnly
type LocationUriOnly struct {
	URI DocumentURI `json:"uri"`
}

// The log message parameters.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#logMessageParams
type LogMessageParams struct {
	// The message type. See {@link MessageType}
	Type MessageType `json:"type"`
	// The actual message.
	Message string `json:"message"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#logTraceParams
type LogTraceParams struct {
	Message string `json:"message"`
	Verbose string `json:"verbose,omitempty"`
}

// Client capabilities specific to the used markdown parser.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#markdownClientCapabilities
type MarkdownClientCapabilities struct {
	// The name of the parser.
	Parser string `json:"parser"`
	// The version of the parser.
	Version string `json:"version,omitempty"`
	// A list of HTML tags that the client allows / supports in
	// Markdown.
	//
	// @since 3.17.0
	AllowedTags []string `json:"allowedTags,omitempty"`
}

// MarkedString can be used to render human readable text. It is either a markdown string
// or a code-block that provides a language and a code snippet. The language identifier
// is semantically equal to the optional language identifier in fenced code blocks in GitHub
// issues. See https://help.github.com/articles/creating-and-highlighting-code-blocks/#syntax-highlighting
//
// The pair of a language and a value is an equivalent to markdown:
// ```${language}
// ${value}
// ```
//
// Note that markdown strings will be sanitized - that means html will be escaped.
// @deprecated use MarkupContent instead.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#markedString
type MarkedString = Or_MarkedString // (alias)
// @since 3.18.0
// @deprecated use MarkupContent instead.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#markedStringWithLanguage
type MarkedStringWithLanguage struct {
	Language string `json:"language"`
	Value    string `json:"value"`
}

// A `MarkupContent` literal represents a string value which content is interpreted base on its
// kind flag. Currently the protocol supports `plaintext` and `markdown` as markup kinds.
//
// If the kind is `markdown` then the value can contain fenced code blocks like in GitHub issues.
// See https://help.github.com/articles/creating-and-highlighting-code-blocks/#syntax-highlighting
//
// Here is an example how such a string can be constructed using JavaScript / TypeScript:
// ```ts
//
//	let markdown: MarkdownContent = {
//	 kind: MarkupKind.Markdown,
//	 value: [
//	   '# Header',
//	   'Some text',
//	   '```typescript',
//	   'someCode();',
//	   '```'
//	 ].join('\n')
//	};
//
// ```
//
// *Please Note* that clients might sanitize the return markdown. A client could decide to
// remove HTML from the markdown to avoid script execution.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#markupContent
type MarkupContent struct {
	// The type of the Markup
	Kind MarkupKind `json:"kind"`
	// The content itself
	Value string `json:"value"`
}

// Describes the content type that a client supports in various
// result literals like `Hover`, `ParameterInfo` or `CompletionItem`.
//
// Please note that `MarkupKinds` must not start with a `$`. This kinds
// are reserved for internal usage.
type MarkupKind string

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#messageActionItem
type MessageActionItem struct {
	// A short title like 'Retry', 'Open Log' etc.
	Title string `json:"title"`
}

// The message type
type MessageType uint32

// Moniker definition to match LSIF 0.5 moniker definition.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#moniker
type Moniker struct {
	// The scheme of the moniker. For example tsc or .Net
	Scheme string `json:"scheme"`
	// The identifier of the moniker. The value is opaque in LSIF however
	// schema owners are allowed to define the structure if they want.
	Identifier string `json:"identifier"`
	// The scope in which the moniker is unique
	Unique UniquenessLevel `json:"unique"`
	// The moniker kind if known.
	Kind *MonikerKind `json:"kind,omitempty"`
}

// Client capabilities specific to the moniker request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#monikerClientCapabilities
type MonikerClientCapabilities struct {
	// Whether moniker supports dynamic registration. If this is set to `true`
	// the client supports the new `MonikerRegistrationOptions` return value
	// for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// The moniker kind.
//
// @since 3.16.0
type MonikerKind string

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#monikerOptions
type MonikerOptions struct {
	WorkDoneProgressOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#monikerParams
type MonikerParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#monikerRegistrationOptions
type MonikerRegistrationOptions struct {
	TextDocumentRegistrationOptions
	MonikerOptions
}

// A notebook cell.
//
// A cell's document URI must be unique across ALL notebook
// cells and can therefore be used to uniquely identify a
// notebook cell or the cell's text document.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookCell
type NotebookCell struct {
	// The cell's kind
	Kind NotebookCellKind `json:"kind"`
	// The URI of the cell's text document
	// content.
	Document DocumentURI `json:"document"`
	// Additional metadata stored with the cell.
	//
	// Note: should always be an object literal (e.g. LSPObject)
	Metadata *LSPObject `json:"metadata,omitempty"`
	// Additional execution summary information
	// if supported by the client.
	ExecutionSummary *ExecutionSummary `json:"executionSummary,omitempty"`
}

// A change describing how to move a `NotebookCell`
// array from state S to S'.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookCellArrayChange
type NotebookCellArrayChange struct {
	// The start oftest of the cell that changed.
	Start uint32 `json:"start"`
	// The deleted cells
	DeleteCount uint32 `json:"deleteCount"`
	// The new cells, if any
	Cells []NotebookCell `json:"cells,omitempty"`
}

// A notebook cell kind.
//
// @since 3.17.0
type NotebookCellKind uint32

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookCellLanguage
type NotebookCellLanguage struct {
	Language string `json:"language"`
}

// A notebook cell text document filter denotes a cell text
// document by different properties.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookCellTextDocumentFilter
type NotebookCellTextDocumentFilter struct {
	// A filter that matches against the notebook
	// containing the notebook cell. If a string
	// value is provided it matches against the
	// notebook type. '*' matches every notebook.
	Notebook Or_NotebookCellTextDocumentFilter_notebook `json:"notebook"`
	// A language id like `python`.
	//
	// Will be matched against the language id of the
	// notebook cell document. '*' matches every language.
	Language string `json:"language,omitempty"`
}

// A notebook document.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocument
type NotebookDocument struct {
	// The notebook document's uri.
	URI URI `json:"uri"`
	// The type of the notebook.
	NotebookType string `json:"notebookType"`
	// The version number of this document (it will increase after each
	// change, including undo/redo).
	Version int32 `json:"version"`
	// Additional metadata stored with the notebook
	// document.
	//
	// Note: should always be an object literal (e.g. LSPObject)
	Metadata *LSPObject `json:"metadata,omitempty"`
	// The cells of a notebook.
	Cells []NotebookCell `json:"cells"`
}

// Structural changes to cells in a notebook document.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentCellChangeStructure
type NotebookDocumentCellChangeStructure struct {
	// The change to the cell array.
	Array NotebookCellArrayChange `json:"array"`
	// Additional opened cell text documents.
	DidOpen []TextDocumentItem `json:"didOpen,omitempty"`
	// Additional closed cell text documents.
	DidClose []TextDocumentIdentifier `json:"didClose,omitempty"`
}

// Cell changes to a notebook document.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentCellChanges
type NotebookDocumentCellChanges struct {
	// Changes to the cell structure to add or
	// remove cells.
	Structure *NotebookDocumentCellChangeStructure `json:"structure,omitempty"`
	// Changes to notebook cells properties like its
	// kind, execution summary or metadata.
	Data []NotebookCell `json:"data,omitempty"`
	// Changes to the text content of notebook cells.
	TextContent []NotebookDocumentCellContentChanges `json:"textContent,omitempty"`
}

// Content changes to a cell in a notebook document.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentCellContentChanges
type NotebookDocumentCellContentChanges struct {
	Document VersionedTextDocumentIdentifier  `json:"document"`
	Changes  []TextDocumentContentChangeEvent `json:"changes"`
}

// A change event for a notebook document.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentChangeEvent
type NotebookDocumentChangeEvent struct {
	// The changed meta data if any.
	//
	// Note: should always be an object literal (e.g. LSPObject)
	Metadata *LSPObject `json:"metadata,omitempty"`
	// Changes to cells
	Cells *NotebookDocumentCellChanges `json:"cells,omitempty"`
}

// Capabilities specific to the notebook document support.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentClientCapabilities
type NotebookDocumentClientCapabilities struct {
	// Capabilities specific to notebook document synchronization
	//
	// @since 3.17.0
	Synchronization NotebookDocumentSyncClientCapabilities `json:"synchronization"`
}

// A notebook document filter denotes a notebook document by
// different properties. The properties will be match
// against the notebook's URI (same as with documents)
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilter
type NotebookDocumentFilter = Or_NotebookDocumentFilter // (alias)
// A notebook document filter where `notebookType` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilterNotebookType
type NotebookDocumentFilterNotebookType struct {
	// The type of the enclosing notebook.
	NotebookType string `json:"notebookType"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme,omitempty"`
	// A glob pattern.
	Pattern *GlobPattern `json:"pattern,omitempty"`
}

// A notebook document filter where `pattern` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilterPattern
type NotebookDocumentFilterPattern struct {
	// The type of the enclosing notebook.
	NotebookType string `json:"notebookType,omitempty"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme,omitempty"`
	// A glob pattern.
	Pattern GlobPattern `json:"pattern"`
}

// A notebook document filter where `scheme` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilterScheme
type NotebookDocumentFilterScheme struct {
	// The type of the enclosing notebook.
	NotebookType string `json:"notebookType,omitempty"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme"`
	// A glob pattern.
	Pattern *GlobPattern `json:"pattern,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilterWithCells
type NotebookDocumentFilterWithCells struct {
	// The notebook to be synced If a string
	// value is provided it matches against the
	// notebook type. '*' matches every notebook.
	Notebook *Or_NotebookDocumentFilterWithCells_notebook `json:"notebook,omitempty"`
	// The cells of the matching notebook to be synced.
	Cells []NotebookCellLanguage `json:"cells"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentFilterWithNotebook
type NotebookDocumentFilterWithNotebook struct {
	// The notebook to be synced If a string
	// value is provided it matches against the
	// notebook type. '*' matches every notebook.
	Notebook Or_NotebookDocumentFilterWithNotebook_notebook `json:"notebook"`
	// The cells of the matching notebook to be synced.
	Cells []NotebookCellLanguage `json:"cells,omitempty"`
}

// A literal to identify a notebook document in the client.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentIdentifier
type NotebookDocumentIdentifier struct {
	// The notebook document's uri.
	URI URI `json:"uri"`
}

// Notebook specific client capabilities.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentSyncClientCapabilities
type NotebookDocumentSyncClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is
	// set to `true` the client supports the new
	// `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports sending execution summary data per cell.
	ExecutionSummarySupport bool `json:"executionSummarySupport,omitempty"`
}

// Options specific to a notebook plus its cells
// to be synced to the server.
//
// If a selector provides a notebook document
// filter but no cell selector all cells of a
// matching notebook document will be synced.
//
// If a selector provides no notebook document
// filter but only a cell selector all notebook
// document that contain at least one matching
// cell will be synced.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentSyncOptions
type NotebookDocumentSyncOptions struct {
	// The notebooks to be synced
	NotebookSelector []Or_NotebookDocumentSyncOptions_notebookSelector_Elem `json:"notebookSelector"`
	// Whether save notification should be forwarded to
	// the server. Will only be honored if mode === `notebook`.
	Save bool `json:"save,omitempty"`
}

// Registration options specific to a notebook.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocumentSyncRegistrationOptions
type NotebookDocumentSyncRegistrationOptions struct {
	NotebookDocumentSyncOptions
	StaticRegistrationOptions
}

// A text document identifier to optionally denote a specific version of a text document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#optionalVersionedTextDocumentIdentifier
type OptionalVersionedTextDocumentIdentifier struct {
	// The version number of this document. If a versioned text document identifier
	// is sent from the server to the client and the file is not open in the editor
	// (the server has not received an open notification before) the server can send
	// `null` to indicate that the version is unknown and the content on disk is the
	// truth (as specified with document content ownership).
	Version int32 `json:"version"`
	TextDocumentIdentifier
}

// created for Or [Location LocationUriOnly]
type OrPLocation_workspace_symbol struct {
	Value any `json:"value"`
}

// created for Or [[]string string]
type OrPSection_workspace_didChangeConfiguration struct {
	Value any `json:"value"`
}

// created for Or [MarkupContent string]
type OrPTooltipPLabel struct {
	Value any `json:"value"`
}

// created for Or [MarkupContent string]
type OrPTooltip_textDocument_inlayHint struct {
	Value any `json:"value"`
}

// created for Or [int32 string]
type Or_CancelParams_id struct {
	Value any `json:"value"`
}

// created for Or [ClientSemanticTokensRequestFullDelta bool]
type Or_ClientSemanticTokensRequestOptions_full struct {
	Value any `json:"value"`
}

// created for Or [Lit_ClientSemanticTokensRequestOptions_range_Item1 bool]
type Or_ClientSemanticTokensRequestOptions_range struct {
	Value any `json:"value"`
}

// created for Or [EditRangeWithInsertReplace Range]
type Or_CompletionItemDefaults_editRange struct {
	Value any `json:"value"`
}

// created for Or [MarkupContent string]
type Or_CompletionItem_documentation struct {
	Value any `json:"value"`
}

// created for Or [InsertReplaceEdit TextEdit]
type Or_CompletionItem_textEdit struct {
	Value any `json:"value"`
}

// created for Or [Location []Location]
type Or_Definition struct {
	Value any `json:"value"`
}

// created for Or [int32 string]
type Or_Diagnostic_code struct {
	Value any `json:"value"`
}

// created for Or [RelatedFullDocumentDiagnosticReport RelatedUnchangedDocumentDiagnosticReport]
type Or_DocumentDiagnosticReport struct {
	Value any `json:"value"`
}

// created for Or [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]
type Or_DocumentDiagnosticReportPartialResult_relatedDocuments_Value struct {
	Value any `json:"value"`
}

// created for Or [NotebookCellTextDocumentFilter TextDocumentFilter]
type Or_DocumentFilter struct {
	Value any `json:"value"`
}

// created for Or [Pattern RelativePattern]
type Or_GlobPattern struct {
	Value any `json:"value"`
}

// created for Or [MarkedString MarkupContent []MarkedString]
type Or_Hover_contents struct {
	Value any `json:"value"`
}

// created for Or [[]InlayHintLabelPart string]
type Or_InlayHint_label struct {
	Value any `json:"value"`
}

// created for Or [StringValue string]
type Or_InlineCompletionItem_insertText struct {
	Value any `json:"value"`
}

// created for Or [InlineValueEvaluatableExpression InlineValueText InlineValueVariableLookup]
type Or_InlineValue struct {
	Value any `json:"value"`
}

// created for Or [MarkedStringWithLanguage string]
type Or_MarkedString struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentFilter string]
type Or_NotebookCellTextDocumentFilter_notebook struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentFilterNotebookType NotebookDocumentFilterPattern NotebookDocumentFilterScheme]
type Or_NotebookDocumentFilter struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentFilter string]
type Or_NotebookDocumentFilterWithCells_notebook struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentFilter string]
type Or_NotebookDocumentFilterWithNotebook_notebook struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentFilterWithCells NotebookDocumentFilterWithNotebook]
type Or_NotebookDocumentSyncOptions_notebookSelector_Elem struct {
	Value any `json:"value"`
}

// created for Or [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]
type Or_RelatedFullDocumentDiagnosticReport_relatedDocuments_Value struct {
	Value any `json:"value"`
}

// created for Or [FullDocumentDiagnosticReport UnchangedDocumentDiagnosticReport]
type Or_RelatedUnchangedDocumentDiagnosticReport_relatedDocuments_Value struct {
	Value any `json:"value"`
}

// created for Or [CodeAction Command]
type Or_Result_textDocument_codeAction_Item0_Elem struct {
	Value any `json:"value"`
}

// created for Or [InlineCompletionList []InlineCompletionItem]
type Or_Result_textDocument_inlineCompletion struct {
	Value any `json:"value"`
}

// created for Or [SemanticTokensFullDelta bool]
type Or_SemanticTokensOptions_full struct {
	Value any `json:"value"`
}

// created for Or [PRangeESemanticTokensOptions bool]
type Or_SemanticTokensOptions_range struct {
	Value any `json:"value"`
}

// created for Or [CallHierarchyOptions CallHierarchyRegistrationOptions bool]
type Or_ServerCapabilities_callHierarchyProvider struct {
	Value any `json:"value"`
}

// created for Or [CodeActionOptions bool]
type Or_ServerCapabilities_codeActionProvider struct {
	Value any `json:"value"`
}

// created for Or [DocumentColorOptions DocumentColorRegistrationOptions bool]
type Or_ServerCapabilities_colorProvider struct {
	Value any `json:"value"`
}

// created for Or [DeclarationOptions DeclarationRegistrationOptions bool]
type Or_ServerCapabilities_declarationProvider struct {
	Value any `json:"value"`
}

// created for Or [DefinitionOptions bool]
type Or_ServerCapabilities_definitionProvider struct {
	Value any `json:"value"`
}

// created for Or [DiagnosticOptions DiagnosticRegistrationOptions]
type Or_ServerCapabilities_diagnosticProvider struct {
	Value any `json:"value"`
}

// created for Or [DocumentFormattingOptions bool]
type Or_ServerCapabilities_documentFormattingProvider struct {
	Value any `json:"value"`
}

// created for Or [DocumentHighlightOptions bool]
type Or_ServerCapabilities_documentHighlightProvider struct {
	Value any `json:"value"`
}

// created for Or [DocumentRangeFormattingOptions bool]
type Or_ServerCapabilities_documentRangeFormattingProvider struct {
	Value any `json:"value"`
}

// created for Or [DocumentSymbolOptions bool]
type Or_ServerCapabilities_documentSymbolProvider struct {
	Value any `json:"value"`
}

// created for Or [FoldingRangeOptions FoldingRangeRegistrationOptions bool]
type Or_ServerCapabilities_foldingRangeProvider struct {
	Value any `json:"value"`
}

// created for Or [HoverOptions bool]
type Or_ServerCapabilities_hoverProvider struct {
	Value any `json:"value"`
}

// created for Or [ImplementationOptions ImplementationRegistrationOptions bool]
type Or_ServerCapabilities_implementationProvider struct {
	Value any `json:"value"`
}

// created for Or [InlayHintOptions InlayHintRegistrationOptions bool]
type Or_ServerCapabilities_inlayHintProvider struct {
	Value any `json:"value"`
}

// created for Or [InlineCompletionOptions bool]
type Or_ServerCapabilities_inlineCompletionProvider struct {
	Value any `json:"value"`
}

// created for Or [InlineValueOptions InlineValueRegistrationOptions bool]
type Or_ServerCapabilities_inlineValueProvider struct {
	Value any `json:"value"`
}

// created for Or [LinkedEditingRangeOptions LinkedEditingRangeRegistrationOptions bool]
type Or_ServerCapabilities_linkedEditingRangeProvider struct {
	Value any `json:"value"`
}

// created for Or [MonikerOptions MonikerRegistrationOptions bool]
type Or_ServerCapabilities_monikerProvider struct {
	Value any `json:"value"`
}

// created for Or [NotebookDocumentSyncOptions NotebookDocumentSyncRegistrationOptions]
type Or_ServerCapabilities_notebookDocumentSync struct {
	Value any `json:"value"`
}

// created for Or [ReferenceOptions bool]
type Or_ServerCapabilities_referencesProvider struct {
	Value any `json:"value"`
}

// created for Or [RenameOptions bool]
type Or_ServerCapabilities_renameProvider struct {
	Value any `json:"value"`
}

// created for Or [SelectionRangeOptions SelectionRangeRegistrationOptions bool]
type Or_ServerCapabilities_selectionRangeProvider struct {
	Value any `json:"value"`
}

// created for Or [SemanticTokensOptions SemanticTokensRegistrationOptions]
type Or_ServerCapabilities_semanticTokensProvider struct {
	Value any `json:"value"`
}

// created for Or [TextDocumentSyncKind TextDocumentSyncOptions]
type Or_ServerCapabilities_textDocumentSync struct {
	Value any `json:"value"`
}

// created for Or [TypeDefinitionOptions TypeDefinitionRegistrationOptions bool]
type Or_ServerCapabilities_typeDefinitionProvider struct {
	Value any `json:"value"`
}

// created for Or [TypeHierarchyOptions TypeHierarchyRegistrationOptions bool]
type Or_ServerCapabilities_typeHierarchyProvider struct {
	Value any `json:"value"`
}

// created for Or [WorkspaceSymbolOptions bool]
type Or_ServerCapabilities_workspaceSymbolProvider struct {
	Value any `json:"value"`
}

// created for Or [MarkupContent string]
type Or_SignatureInformation_documentation struct {
	Value any `json:"value"`
}

// created for Or [AnnotatedTextEdit SnippetTextEdit TextEdit]
type Or_TextDocumentEdit_edits_Elem struct {
	Value any `json:"value"`
}

// created for Or [TextDocumentFilterLanguage TextDocumentFilterPattern TextDocumentFilterScheme]
type Or_TextDocumentFilter struct {
	Value any `json:"value"`
}

// created for Or [SaveOptions bool]
type Or_TextDocumentSyncOptions_save struct {
	Value any `json:"value"`
}

// created for Or [WorkspaceFullDocumentDiagnosticReport WorkspaceUnchangedDocumentDiagnosticReport]
type Or_WorkspaceDocumentDiagnosticReport struct {
	Value any `json:"value"`
}

// created for Or [CreateFile DeleteFile RenameFile TextDocumentEdit]
type Or_WorkspaceEdit_documentChanges_Elem struct {
	Value any `json:"value"`
}

// created for Or [TextDocumentContentOptions TextDocumentContentRegistrationOptions]
type Or_WorkspaceOptions_textDocumentContent struct {
	Value any `json:"value"`
}

// created for Or [Declaration []DeclarationLink]
type Or_textDocument_declaration struct {
	Value any `json:"value"`
}

// created for Literal (Lit_SemanticTokensOptions_range_Item1)
type PRangeESemanticTokensOptions struct {
}

// The parameters of a configuration request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#configurationParams
type ParamConfiguration struct {
	Items []ConfigurationItem `json:"items"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initializeParams
type ParamInitialize struct {
	XInitializeParams
	WorkspaceFoldersInitializeParams
}

// Represents a parameter of a callable-signature. A parameter can
// have a label and a doc-comment.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#parameterInformation
type ParameterInformation struct {
	// The label of this parameter information.
	//
	// Either a string or an inclusive start and exclusive end offsets within its containing
	// signature label. (see SignatureInformation.label). The offsets are based on a UTF-16
	// string representation as `Position` and `Range` does.
	//
	// To avoid ambiguities a server should use the [start, end] offset value instead of using
	// a substring. Whether a client support this is controlled via `labelOffsetSupport` client
	// capability.
	//
	// *Note*: a label of type string should be a substring of its containing signature label.
	// Its intended use case is to highlight the parameter label part in the `SignatureInformation.label`.
	Label string `json:"label"`
	// The human-readable doc-comment of this parameter. Will be shown
	// in the UI but can be omitted.
	Documentation string `json:"documentation,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#partialResultParams
type PartialResultParams struct {
	// An optional token that a server can use to report partial results (e.g. streaming) to
	// the client.
	PartialResultToken *ProgressToken `json:"partialResultToken,omitempty"`
}

// The glob pattern to watch relative to the base path. Glob patterns can have the following syntax:
//
//   - `*` to match one or more characters in a path segment
//   - `?` to match on one character in a path segment
//   - `**` to match any number of path segments, including none
//   - `{}` to group conditions (e.g. `**​/*.{ts,js}` matches all TypeScript and JavaScript files)
//   - `[]` to declare a range of characters to match in a path segment (e.g., `example.[0-9]` to match on `example.0`, `example.1`, …)
//   - `[!...]` to negate a range of characters to match in a path segment (e.g., `example.[!0-9]` to match on `example.a`, `example.b`, but not `example.0`)
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#pattern
type Pattern = string // (alias)
// Position in a text document expressed as zero-based line and character
// offset. Prior to 3.17 the offsets were always based on a UTF-16 string
// representation. So a string of the form `a𐐀b` the character offset of the
// character `a` is 0, the character offset of `𐐀` is 1 and the character
// offset of b is 3 since `𐐀` is represented using two code units in UTF-16.
// Since 3.17 clients and servers can agree on a different string encoding
// representation (e.g. UTF-8). The client announces it's supported encoding
// via the client capability [`general.positionEncodings`](https://microsoft.github.io/language-server-protocol/specifications/specification-current/#clientCapabilities).
// The value is an array of position encodings the client supports, with
// decreasing preference (e.g. the encoding at index `0` is the most preferred
// one). To stay backwards compatible the only mandatory encoding is UTF-16
// represented via the string `utf-16`. The server can pick one of the
// encodings offered by the client and signals that encoding back to the
// client via the initialize result's property
// [`capabilities.positionEncoding`](https://microsoft.github.io/language-server-protocol/specifications/specification-current/#serverCapabilities). If the string value
// `utf-16` is missing from the client's capability `general.positionEncodings`
// servers can safely assume that the client supports UTF-16. If the server
// omits the position encoding in its initialize result the encoding defaults
// to the string value `utf-16`. Implementation considerations: since the
// conversion from one encoding into another requires the content of the
// file / line the conversion is best done where the file is read which is
// usually on the server side.
//
// Positions are line end character agnostic. So you can not specify a position
// that denotes `\r|\n` or `\n|` where `|` represents the character offset.
//
// @since 3.17.0 - support for negotiated position encoding.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#position
type Position struct {
	// Line position in a document (zero-based).
	Line uint32 `json:"line"`
	// Character offset on a line in a document (zero-based).
	//
	// The meaning of this offset is determined by the negotiated
	// `PositionEncodingKind`.
	Character uint32 `json:"character"`
}

// A set of predefined position encoding kinds.
//
// @since 3.17.0
type PositionEncodingKind string

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#prepareRenameDefaultBehavior
type PrepareRenameDefaultBehavior struct {
	DefaultBehavior bool `json:"defaultBehavior"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#prepareRenameParams
type PrepareRenameParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#prepareRenamePlaceholder
type PrepareRenamePlaceholder struct {
	Range       Range  `json:"range"`
	Placeholder string `json:"placeholder"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#prepareRenameResult
type PrepareRenameResult = PrepareRenamePlaceholder // (alias)
type PrepareSupportDefaultBehavior uint32

// A previous result id in a workspace pull request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#previousResultId
type PreviousResultID struct {
	// The URI for which the client knowns a
	// result id.
	URI DocumentURI `json:"uri"`
	// The value of the previous result id.
	Value string `json:"value"`
}

// A previous result id in a workspace pull request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#previousResultId
type PreviousResultId struct {
	// The URI for which the client knowns a
	// result id.
	URI DocumentURI `json:"uri"`
	// The value of the previous result id.
	Value string `json:"value"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#progressParams
type ProgressParams struct {
	// The progress token provided by the client or server.
	Token ProgressToken `json:"token"`
	// The progress data.
	Value any `json:"value"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#progressToken
type ProgressToken = any // (alias)
// The publish diagnostic client capabilities.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#publishDiagnosticsClientCapabilities
type PublishDiagnosticsClientCapabilities struct {
	// Whether the client interprets the version property of the
	// `textDocument/publishDiagnostics` notification's parameter.
	//
	// @since 3.15.0
	VersionSupport bool `json:"versionSupport,omitempty"`
	DiagnosticsCapabilities
}

// The publish diagnostic notification's parameters.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#publishDiagnosticsParams
type PublishDiagnosticsParams struct {
	// The URI for which diagnostic information is reported.
	URI DocumentURI `json:"uri"`
	// Optional the version number of the document the diagnostics are published for.
	//
	// @since 3.15.0
	Version int32 `json:"version,omitempty"`
	// An array of diagnostic information items.
	Diagnostics []Diagnostic `json:"diagnostics"`
}

// A range in a text document expressed as (zero-based) start and end positions.
//
// If you want to specify a range that contains a line including the line ending
// character(s) then use an end position denoting the start of the next line.
// For example:
// ```ts
//
//	{
//	    start: { line: 5, character: 23 }
//	    end : { line 6, character : 0 }
//	}
//
// ```
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#range
type Range struct {
	// The range's start position.
	Start Position `json:"start"`
	// The range's end position.
	End Position `json:"end"`
}

// Client Capabilities for a {@link ReferencesRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#referenceClientCapabilities
type ReferenceClientCapabilities struct {
	// Whether references supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Value-object that contains additional information when
// requesting references.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#referenceContext
type ReferenceContext struct {
	// Include the declaration of the current symbol.
	IncludeDeclaration bool `json:"includeDeclaration"`
}

// Reference options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#referenceOptions
type ReferenceOptions struct {
	WorkDoneProgressOptions
}

// Parameters for a {@link ReferencesRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#referenceParams
type ReferenceParams struct {
	Context ReferenceContext `json:"context"`
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link ReferencesRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#referenceRegistrationOptions
type ReferenceRegistrationOptions struct {
	TextDocumentRegistrationOptions
	ReferenceOptions
}

// General parameters to register for a notification or to register a provider.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#registration
type Registration struct {
	// The id used to register the request. The id can be used to deregister
	// the request again.
	ID string `json:"id"`
	// The method / capability to register for.
	Method string `json:"method"`
	// Options necessary for the registration.
	RegisterOptions any `json:"registerOptions,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#registrationParams
type RegistrationParams struct {
	Registrations []Registration `json:"registrations"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#regularExpressionEngineKind
type RegularExpressionEngineKind = string // (alias)
// Client capabilities specific to regular expressions.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#regularExpressionsClientCapabilities
type RegularExpressionsClientCapabilities struct {
	// The engine's name.
	Engine RegularExpressionEngineKind `json:"engine"`
	// The engine's version.
	Version string `json:"version,omitempty"`
}

// A full diagnostic report with a set of related documents.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#relatedFullDocumentDiagnosticReport
type RelatedFullDocumentDiagnosticReport struct {
	// Diagnostics of related documents. This information is useful
	// in programming languages where code in a file A can generate
	// diagnostics in a file B which A depends on. An example of
	// such a language is C/C++ where marco definitions in a file
	// a.cpp and result in errors in a header file b.hpp.
	//
	// @since 3.17.0
	RelatedDocuments map[DocumentURI]any `json:"relatedDocuments,omitempty"`
	FullDocumentDiagnosticReport
}

// An unchanged diagnostic report with a set of related documents.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#relatedUnchangedDocumentDiagnosticReport
type RelatedUnchangedDocumentDiagnosticReport struct {
	// Diagnostics of related documents. This information is useful
	// in programming languages where code in a file A can generate
	// diagnostics in a file B which A depends on. An example of
	// such a language is C/C++ where marco definitions in a file
	// a.cpp and result in errors in a header file b.hpp.
	//
	// @since 3.17.0
	RelatedDocuments map[DocumentURI]any `json:"relatedDocuments,omitempty"`
	UnchangedDocumentDiagnosticReport
}

// A relative pattern is a helper to construct glob patterns that are matched
// relatively to a base URI. The common value for a `baseUri` is a workspace
// folder root, but it can be another absolute URI as well.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#relativePattern
type RelativePattern struct {
	// A workspace folder or a base URI to which this pattern will be matched
	// against relatively.
	BaseURI DocumentURI `json:"baseUri"`
	// The actual glob pattern;
	Pattern Pattern `json:"pattern"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameClientCapabilities
type RenameClientCapabilities struct {
	// Whether rename supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Client supports testing for validity of rename operations
	// before execution.
	//
	// @since 3.12.0
	PrepareSupport bool `json:"prepareSupport,omitempty"`
	// Client supports the default behavior result.
	//
	// The value indicates the default behavior used by the
	// client.
	//
	// @since 3.16.0
	PrepareSupportDefaultBehavior *PrepareSupportDefaultBehavior `json:"prepareSupportDefaultBehavior,omitempty"`
	// Whether the client honors the change annotations in
	// text edits and resource operations returned via the
	// rename request's workspace edit by for example presenting
	// the workspace edit in the user interface and asking
	// for confirmation.
	//
	// @since 3.16.0
	HonorsChangeAnnotations bool `json:"honorsChangeAnnotations,omitempty"`
}

// Rename file operation
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameFile
type RenameFile struct {
	// A rename
	Kind string `json:"kind"`
	// The old (existing) location.
	OldURI DocumentURI `json:"oldUri"`
	// The new location.
	NewURI DocumentURI `json:"newUri"`
	// Rename options.
	Options *RenameFileOptions `json:"options,omitempty"`
	ResourceOperation
}

// Rename file options
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameFileOptions
type RenameFileOptions struct {
	// Overwrite target if existing. Overwrite wins over `ignoreIfExists`
	Overwrite bool `json:"overwrite,omitempty"`
	// Ignores if target exists.
	IgnoreIfExists bool `json:"ignoreIfExists,omitempty"`
}

// The parameters sent in notifications/requests for user-initiated renames of
// files.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameFilesParams
type RenameFilesParams struct {
	// An array of all files/folders renamed in this operation. When a folder is renamed, only
	// the folder will be included, and not its children.
	Files []FileRename `json:"files"`
}

// Provider options for a {@link RenameRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameOptions
type RenameOptions struct {
	// Renames should be checked and tested before being executed.
	//
	// @since version 3.12.0
	PrepareProvider bool `json:"prepareProvider,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link RenameRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameParams
type RenameParams struct {
	// The new name of the symbol. If the given name is not valid the
	// request must return a {@link ResponseError} with an
	// appropriate message set.
	NewName string `json:"newName"`
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Registration options for a {@link RenameRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#renameRegistrationOptions
type RenameRegistrationOptions struct {
	TextDocumentRegistrationOptions
	RenameOptions
}

// A generic resource operation.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#resourceOperation
type ResourceOperation struct {
	// The resource operation kind.
	Kind string `json:"kind"`
	// An optional annotation identifier describing the operation.
	//
	// @since 3.16.0
	AnnotationID *ChangeAnnotationIdentifier `json:"annotationId,omitempty"`
}
type ResourceOperationKind string

// Save options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#saveOptions
type SaveOptions struct {
	// The client is supposed to include the content on save.
	IncludeText bool `json:"includeText,omitempty"`
}

// Describes the currently selected completion item.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectedCompletionInfo
type SelectedCompletionInfo struct {
	// The range that will be replaced if this completion item is accepted.
	Range Range `json:"range"`
	// The text the range will be replaced with if this completion is accepted.
	Text string `json:"text"`
}

// A selection range represents a part of a selection hierarchy. A selection range
// may have a parent selection range that contains it.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectionRange
type SelectionRange struct {
	// The {@link Range range} of this selection range.
	Range Range `json:"range"`
	// The parent selection range containing this range. Therefore `parent.range` must contain `this.range`.
	Parent *SelectionRange `json:"parent,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectionRangeClientCapabilities
type SelectionRangeClientCapabilities struct {
	// Whether implementation supports dynamic registration for selection range providers. If this is set to `true`
	// the client supports the new `SelectionRangeRegistrationOptions` return value for the corresponding server
	// capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectionRangeOptions
type SelectionRangeOptions struct {
	WorkDoneProgressOptions
}

// A parameter literal used in selection range requests.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectionRangeParams
type SelectionRangeParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The positions inside the text document.
	Positions []Position `json:"positions"`
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#selectionRangeRegistrationOptions
type SelectionRangeRegistrationOptions struct {
	SelectionRangeOptions
	TextDocumentRegistrationOptions
	StaticRegistrationOptions
}

// A set of predefined token modifiers. This set is not fixed
// an clients can specify additional token types via the
// corresponding client capabilities.
//
// @since 3.16.0
type SemanticTokenModifiers string

// A set of predefined token types. This set is not fixed
// an clients can specify additional token types via the
// corresponding client capabilities.
//
// @since 3.16.0
type SemanticTokenTypes string

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokens
type SemanticTokens struct {
	// An optional result id. If provided and clients support delta updating
	// the client will include the result id in the next semantic token request.
	// A server can then instead of computing all semantic tokens again simply
	// send a delta.
	ResultID string `json:"resultId,omitempty"`
	// The actual tokens.
	Data []uint32 `json:"data"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensClientCapabilities
type SemanticTokensClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Which requests the client supports and might send to the server
	// depending on the server's capability. Please note that clients might not
	// show semantic tokens or degrade some of the user experience if a range
	// or full request is advertised by the client but not provided by the
	// server. If for example the client capability `requests.full` and
	// `request.range` are both set to true but the server only provides a
	// range provider the client might not render a minimap correctly or might
	// even decide to not show any semantic tokens at all.
	Requests ClientSemanticTokensRequestOptions `json:"requests"`
	// The token types that the client supports.
	TokenTypes []string `json:"tokenTypes"`
	// The token modifiers that the client supports.
	TokenModifiers []string `json:"tokenModifiers"`
	// The token formats the clients supports.
	Formats []TokenFormat `json:"formats"`
	// Whether the client supports tokens that can overlap each other.
	OverlappingTokenSupport bool `json:"overlappingTokenSupport,omitempty"`
	// Whether the client supports tokens that can span multiple lines.
	MultilineTokenSupport bool `json:"multilineTokenSupport,omitempty"`
	// Whether the client allows the server to actively cancel a
	// semantic token request, e.g. supports returning
	// LSPErrorCodes.ServerCancelled. If a server does the client
	// needs to retrigger the request.
	//
	// @since 3.17.0
	ServerCancelSupport bool `json:"serverCancelSupport,omitempty"`
	// Whether the client uses semantic tokens to augment existing
	// syntax tokens. If set to `true` client side created syntax
	// tokens and semantic tokens are both used for colorization. If
	// set to `false` the client only uses the returned semantic tokens
	// for colorization.
	//
	// If the value is `undefined` then the client behavior is not
	// specified.
	//
	// @since 3.17.0
	AugmentsSyntaxTokens bool `json:"augmentsSyntaxTokens,omitempty"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensDelta
type SemanticTokensDelta struct {
	ResultID string `json:"resultId,omitempty"`
	// The semantic token edits to transform a previous result into a new result.
	Edits []SemanticTokensEdit `json:"edits"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensDeltaParams
type SemanticTokensDeltaParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The result id of a previous response. The result Id can either point to a full response
	// or a delta response depending on what was received last.
	PreviousResultID string `json:"previousResultId"`
	WorkDoneProgressParams
	PartialResultParams
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensDeltaPartialResult
type SemanticTokensDeltaPartialResult struct {
	Edits []SemanticTokensEdit `json:"edits"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensEdit
type SemanticTokensEdit struct {
	// The start offset of the edit.
	Start uint32 `json:"start"`
	// The count of elements to remove.
	DeleteCount uint32 `json:"deleteCount"`
	// The elements to insert.
	Data []uint32 `json:"data,omitempty"`
}

// Semantic tokens options to support deltas for full documents
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensFullDelta
type SemanticTokensFullDelta struct {
	// The server supports deltas for full documents.
	Delta bool `json:"delta,omitempty"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensLegend
type SemanticTokensLegend struct {
	// The token types a server uses.
	TokenTypes []string `json:"tokenTypes"`
	// The token modifiers a server uses.
	TokenModifiers []string `json:"tokenModifiers"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensOptions
type SemanticTokensOptions struct {
	// The legend used by the server
	Legend SemanticTokensLegend `json:"legend"`
	// Server supports providing semantic tokens for a specific range
	// of a document.
	Range *Or_SemanticTokensOptions_range `json:"range,omitempty"`
	// Server supports providing semantic tokens for a full document.
	Full *Or_SemanticTokensOptions_full `json:"full,omitempty"`
	WorkDoneProgressOptions
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensParams
type SemanticTokensParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	WorkDoneProgressParams
	PartialResultParams
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensPartialResult
type SemanticTokensPartialResult struct {
	Data []uint32 `json:"data"`
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensRangeParams
type SemanticTokensRangeParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The range the semantic tokens are requested for.
	Range Range `json:"range"`
	WorkDoneProgressParams
	PartialResultParams
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensRegistrationOptions
type SemanticTokensRegistrationOptions struct {
	TextDocumentRegistrationOptions
	SemanticTokensOptions
	StaticRegistrationOptions
}

// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#semanticTokensWorkspaceClientCapabilities
type SemanticTokensWorkspaceClientCapabilities struct {
	// Whether the client implementation supports a refresh request sent from
	// the server to the client.
	//
	// Note that this event is global and will force the client to refresh all
	// semantic tokens currently shown. It should be used with absolute care
	// and is useful for situation where a server for example detects a project
	// wide change that requires such a calculation.
	RefreshSupport bool `json:"refreshSupport,omitempty"`
}

// Defines the capabilities provided by a language
// server.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#serverCapabilities
type ServerCapabilities struct {
	// The position encoding the server picked from the encodings offered
	// by the client via the client capability `general.positionEncodings`.
	//
	// If the client didn't provide any position encodings the only valid
	// value that a server can return is 'utf-16'.
	//
	// If omitted it defaults to 'utf-16'.
	//
	// @since 3.17.0
	PositionEncoding *PositionEncodingKind `json:"positionEncoding,omitempty"`
	// Defines how text documents are synced. Is either a detailed structure
	// defining each notification or for backwards compatibility the
	// TextDocumentSyncKind number.
	TextDocumentSync any `json:"textDocumentSync,omitempty"`
	// Defines how notebook documents are synced.
	//
	// @since 3.17.0
	NotebookDocumentSync *Or_ServerCapabilities_notebookDocumentSync `json:"notebookDocumentSync,omitempty"`
	// The server provides completion support.
	CompletionProvider *CompletionOptions `json:"completionProvider,omitempty"`
	// The server provides hover support.
	HoverProvider *Or_ServerCapabilities_hoverProvider `json:"hoverProvider,omitempty"`
	// The server provides signature help support.
	SignatureHelpProvider *SignatureHelpOptions `json:"signatureHelpProvider,omitempty"`
	// The server provides Goto Declaration support.
	DeclarationProvider *Or_ServerCapabilities_declarationProvider `json:"declarationProvider,omitempty"`
	// The server provides goto definition support.
	DefinitionProvider *Or_ServerCapabilities_definitionProvider `json:"definitionProvider,omitempty"`
	// The server provides Goto Type Definition support.
	TypeDefinitionProvider *Or_ServerCapabilities_typeDefinitionProvider `json:"typeDefinitionProvider,omitempty"`
	// The server provides Goto Implementation support.
	ImplementationProvider *Or_ServerCapabilities_implementationProvider `json:"implementationProvider,omitempty"`
	// The server provides find references support.
	ReferencesProvider *Or_ServerCapabilities_referencesProvider `json:"referencesProvider,omitempty"`
	// The server provides document highlight support.
	DocumentHighlightProvider *Or_ServerCapabilities_documentHighlightProvider `json:"documentHighlightProvider,omitempty"`
	// The server provides document symbol support.
	DocumentSymbolProvider *Or_ServerCapabilities_documentSymbolProvider `json:"documentSymbolProvider,omitempty"`
	// The server provides code actions. CodeActionOptions may only be
	// specified if the client states that it supports
	// `codeActionLiteralSupport` in its initial `initialize` request.
	CodeActionProvider any `json:"codeActionProvider,omitempty"`
	// The server provides code lens.
	CodeLensProvider *CodeLensOptions `json:"codeLensProvider,omitempty"`
	// The server provides document link support.
	DocumentLinkProvider *DocumentLinkOptions `json:"documentLinkProvider,omitempty"`
	// The server provides color provider support.
	ColorProvider *Or_ServerCapabilities_colorProvider `json:"colorProvider,omitempty"`
	// The server provides workspace symbol support.
	WorkspaceSymbolProvider *Or_ServerCapabilities_workspaceSymbolProvider `json:"workspaceSymbolProvider,omitempty"`
	// The server provides document formatting.
	DocumentFormattingProvider *Or_ServerCapabilities_documentFormattingProvider `json:"documentFormattingProvider,omitempty"`
	// The server provides document range formatting.
	DocumentRangeFormattingProvider *Or_ServerCapabilities_documentRangeFormattingProvider `json:"documentRangeFormattingProvider,omitempty"`
	// The server provides document formatting on typing.
	DocumentOnTypeFormattingProvider *DocumentOnTypeFormattingOptions `json:"documentOnTypeFormattingProvider,omitempty"`
	// The server provides rename support. RenameOptions may only be
	// specified if the client states that it supports
	// `prepareSupport` in its initial `initialize` request.
	RenameProvider any `json:"renameProvider,omitempty"`
	// The server provides folding provider support.
	FoldingRangeProvider *Or_ServerCapabilities_foldingRangeProvider `json:"foldingRangeProvider,omitempty"`
	// The server provides selection range support.
	SelectionRangeProvider *Or_ServerCapabilities_selectionRangeProvider `json:"selectionRangeProvider,omitempty"`
	// The server provides execute command support.
	ExecuteCommandProvider *ExecuteCommandOptions `json:"executeCommandProvider,omitempty"`
	// The server provides call hierarchy support.
	//
	// @since 3.16.0
	CallHierarchyProvider *Or_ServerCapabilities_callHierarchyProvider `json:"callHierarchyProvider,omitempty"`
	// The server provides linked editing range support.
	//
	// @since 3.16.0
	LinkedEditingRangeProvider *Or_ServerCapabilities_linkedEditingRangeProvider `json:"linkedEditingRangeProvider,omitempty"`
	// The server provides semantic tokens support.
	//
	// @since 3.16.0
	SemanticTokensProvider any `json:"semanticTokensProvider,omitempty"`
	// The server provides moniker support.
	//
	// @since 3.16.0
	MonikerProvider *Or_ServerCapabilities_monikerProvider `json:"monikerProvider,omitempty"`
	// The server provides type hierarchy support.
	//
	// @since 3.17.0
	TypeHierarchyProvider *Or_ServerCapabilities_typeHierarchyProvider `json:"typeHierarchyProvider,omitempty"`
	// The server provides inline values.
	//
	// @since 3.17.0
	InlineValueProvider *Or_ServerCapabilities_inlineValueProvider `json:"inlineValueProvider,omitempty"`
	// The server provides inlay hints.
	//
	// @since 3.17.0
	InlayHintProvider any `json:"inlayHintProvider,omitempty"`
	// The server has support for pull model diagnostics.
	//
	// @since 3.17.0
	DiagnosticProvider *Or_ServerCapabilities_diagnosticProvider `json:"diagnosticProvider,omitempty"`
	// Inline completion options used during static registration.
	//
	// @since 3.18.0
	// @proposed
	InlineCompletionProvider *Or_ServerCapabilities_inlineCompletionProvider `json:"inlineCompletionProvider,omitempty"`
	// Workspace specific server capabilities.
	Workspace *WorkspaceOptions `json:"workspace,omitempty"`
	// Experimental server capabilities.
	Experimental any `json:"experimental,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#serverCompletionItemOptions
type ServerCompletionItemOptions struct {
	// The server has support for completion item label
	// details (see also `CompletionItemLabelDetails`) when
	// receiving a completion item in a resolve call.
	//
	// @since 3.17.0
	LabelDetailsSupport bool `json:"labelDetailsSupport,omitempty"`
}

// Information about the server
//
// @since 3.15.0
// @since 3.18.0 ServerInfo type name added.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#serverInfo
type ServerInfo struct {
	// The name of the server as defined by the server.
	Name string `json:"name"`
	// The server's version as defined by the server.
	Version string `json:"version,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#setTraceParams
type SetTraceParams struct {
	Value TraceValue `json:"value"`
}

// Client capabilities for the showDocument request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showDocumentClientCapabilities
type ShowDocumentClientCapabilities struct {
	// The client has support for the showDocument
	// request.
	Support bool `json:"support"`
}

// Params to show a resource in the UI.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showDocumentParams
type ShowDocumentParams struct {
	// The uri to show.
	URI URI `json:"uri"`
	// Indicates to show the resource in an external program.
	// To show, for example, `https://code.visualstudio.com/`
	// in the default WEB browser set `external` to `true`.
	External bool `json:"external,omitempty"`
	// An optional property to indicate whether the editor
	// showing the document should take focus or not.
	// Clients might ignore this property if an external
	// program is started.
	TakeFocus bool `json:"takeFocus,omitempty"`
	// An optional selection range if the document is a text
	// document. Clients might ignore the property if an
	// external program is started or the file is not a text
	// file.
	Selection *Range `json:"selection,omitempty"`
}

// The result of a showDocument request.
//
// @since 3.16.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showDocumentResult
type ShowDocumentResult struct {
	// A boolean indicating if the show was successful.
	Success bool `json:"success"`
}

// The parameters of a notification message.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showMessageParams
type ShowMessageParams struct {
	// The message type. See {@link MessageType}
	Type MessageType `json:"type"`
	// The actual message.
	Message string `json:"message"`
}

// Show message request client capabilities
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showMessageRequestClientCapabilities
type ShowMessageRequestClientCapabilities struct {
	// Capabilities specific to the `MessageActionItem` type.
	MessageActionItem *ClientShowMessageActionItemOptions `json:"messageActionItem,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#showMessageRequestParams
type ShowMessageRequestParams struct {
	// The message type. See {@link MessageType}
	Type MessageType `json:"type"`
	// The actual message.
	Message string `json:"message"`
	// The message action items to present.
	Actions []MessageActionItem `json:"actions,omitempty"`
}

// Signature help represents the signature of something
// callable. There can be multiple signature but only one
// active and only one active parameter.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelp
type SignatureHelp struct {
	// One or more signatures.
	Signatures []SignatureInformation `json:"signatures"`
	// The active signature. If omitted or the value lies outside the
	// range of `signatures` the value defaults to zero or is ignored if
	// the `SignatureHelp` has no signatures.
	//
	// Whenever possible implementors should make an active decision about
	// the active signature and shouldn't rely on a default value.
	//
	// In future version of the protocol this property might become
	// mandatory to better express this.
	ActiveSignature uint32 `json:"activeSignature"`
	// The active parameter of the active signature.
	//
	// If `null`, no parameter of the signature is active (for example a named
	// argument that does not match any declared parameters). This is only valid
	// if the client specifies the client capability
	// `textDocument.signatureHelp.noActiveParameterSupport === true`
	//
	// If omitted or the value lies outside the range of
	// `signatures[activeSignature].parameters` defaults to 0 if the active
	// signature has parameters.
	//
	// If the active signature has no parameters it is ignored.
	//
	// In future version of the protocol this property might become
	// mandatory (but still nullable) to better express the active parameter if
	// the active signature does have any.
	ActiveParameter *uint32 `json:"activeParameter,omitempty"`
}

// Client Capabilities for a {@link SignatureHelpRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelpClientCapabilities
type SignatureHelpClientCapabilities struct {
	// Whether signature help supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports the following `SignatureInformation`
	// specific properties.
	SignatureInformation *ClientSignatureInformationOptions `json:"signatureInformation,omitempty"`
	// The client supports to send additional context information for a
	// `textDocument/signatureHelp` request. A client that opts into
	// contextSupport will also support the `retriggerCharacters` on
	// `SignatureHelpOptions`.
	//
	// @since 3.15.0
	ContextSupport bool `json:"contextSupport,omitempty"`
}

// Additional information about the context in which a signature help request was triggered.
//
// @since 3.15.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelpContext
type SignatureHelpContext struct {
	// Action that caused signature help to be triggered.
	TriggerKind SignatureHelpTriggerKind `json:"triggerKind"`
	// Character that caused signature help to be triggered.
	//
	// This is undefined when `triggerKind !== SignatureHelpTriggerKind.TriggerCharacter`
	TriggerCharacter string `json:"triggerCharacter,omitempty"`
	// `true` if signature help was already showing when it was triggered.
	//
	// Retriggers occurs when the signature help is already active and can be caused by actions such as
	// typing a trigger character, a cursor move, or document content changes.
	IsRetrigger bool `json:"isRetrigger"`
	// The currently active `SignatureHelp`.
	//
	// The `activeSignatureHelp` has its `SignatureHelp.activeSignature` field updated based on
	// the user navigating through available signatures.
	ActiveSignatureHelp *SignatureHelp `json:"activeSignatureHelp,omitempty"`
}

// Server Capabilities for a {@link SignatureHelpRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelpOptions
type SignatureHelpOptions struct {
	// List of characters that trigger signature help automatically.
	TriggerCharacters []string `json:"triggerCharacters,omitempty"`
	// List of characters that re-trigger signature help.
	//
	// These trigger characters are only active when signature help is already showing. All trigger characters
	// are also counted as re-trigger characters.
	//
	// @since 3.15.0
	RetriggerCharacters []string `json:"retriggerCharacters,omitempty"`
	WorkDoneProgressOptions
}

// Parameters for a {@link SignatureHelpRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelpParams
type SignatureHelpParams struct {
	// The signature help context. This is only available if the client specifies
	// to send this using the client capability `textDocument.signatureHelp.contextSupport === true`
	//
	// @since 3.15.0
	Context *SignatureHelpContext `json:"context,omitempty"`
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Registration options for a {@link SignatureHelpRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureHelpRegistrationOptions
type SignatureHelpRegistrationOptions struct {
	TextDocumentRegistrationOptions
	SignatureHelpOptions
}

// How a signature help was triggered.
//
// @since 3.15.0
type SignatureHelpTriggerKind uint32

// Represents the signature of something callable. A signature
// can have a label, like a function-name, a doc-comment, and
// a set of parameters.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#signatureInformation
type SignatureInformation struct {
	// The label of this signature. Will be shown in
	// the UI.
	Label string `json:"label"`
	// The human-readable doc-comment of this signature. Will be shown
	// in the UI but can be omitted.
	Documentation *Or_SignatureInformation_documentation `json:"documentation,omitempty"`
	// The parameters of this signature.
	Parameters []ParameterInformation `json:"parameters,omitempty"`
	// The index of the active parameter.
	//
	// If `null`, no parameter of the signature is active (for example a named
	// argument that does not match any declared parameters). This is only valid
	// if the client specifies the client capability
	// `textDocument.signatureHelp.noActiveParameterSupport === true`
	//
	// If provided (or `null`), this is used in place of
	// `SignatureHelp.activeParameter`.
	//
	// @since 3.16.0
	ActiveParameter *uint32 `json:"activeParameter,omitempty"`
}

// An interactive text edit.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#snippetTextEdit
type SnippetTextEdit struct {
	// The range of the text document to be manipulated.
	Range Range `json:"range"`
	// The snippet to be inserted.
	Snippet StringValue `json:"snippet"`
	// The actual identifier of the snippet edit.
	AnnotationID *ChangeAnnotationIdentifier `json:"annotationId,omitempty"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#staleRequestSupportOptions
type StaleRequestSupportOptions struct {
	// The client will actively cancel the request.
	Cancel bool `json:"cancel"`
	// The list of requests for which the client
	// will retry the request if it receives a
	// response with error code `ContentModified`
	RetryOnContentModified []string `json:"retryOnContentModified"`
}

// Static registration options to be returned in the initialize
// request.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#staticRegistrationOptions
type StaticRegistrationOptions struct {
	// The id used to register the request. The id can be used to deregister
	// the request again. See also Registration#id.
	ID string `json:"id,omitempty"`
}

// A string value used as a snippet is a template which allows to insert text
// and to control the editor cursor when insertion happens.
//
// A snippet can define tab stops and placeholders with `$1`, `$2`
// and `${3:foo}`. `$0` defines the final tab stop, it defaults to
// the end of the snippet. Variables are defined with `$name` and
// `${name:default value}`.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#stringValue
type StringValue struct {
	// The kind of string value.
	Kind string `json:"kind"`
	// The snippet string.
	Value string `json:"value"`
}

// Represents information about programming constructs like variables, classes,
// interfaces etc.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#symbolInformation
type SymbolInformation struct {
	// extends BaseSymbolInformation
	// Indicates if this symbol is deprecated.
	//
	// @deprecated Use tags instead
	Deprecated bool `json:"deprecated,omitempty"`
	// The location of this symbol. The location's range is used by a tool
	// to reveal the location in the editor. If the symbol is selected in the
	// tool the range's start information is used to position the cursor. So
	// the range usually spans more than the actual symbol's name and does
	// normally include things like visibility modifiers.
	//
	// The range doesn't have to denote a node range in the sense of an abstract
	// syntax tree. It can therefore not be used to re-construct a hierarchy of
	// the symbols.
	Location Location `json:"location"`
	// The name of this symbol.
	Name string `json:"name"`
	// The kind of this symbol.
	Kind SymbolKind `json:"kind"`
	// Tags for this symbol.
	//
	// @since 3.16.0
	Tags []SymbolTag `json:"tags,omitempty"`
	// The name of the symbol containing this symbol. This information is for
	// user interface purposes (e.g. to render a qualifier in the user interface
	// if necessary). It can't be used to re-infer a hierarchy for the document
	// symbols.
	ContainerName string `json:"containerName,omitempty"`
}

// A symbol kind.
type SymbolKind uint32

// Symbol tags are extra annotations that tweak the rendering of a symbol.
//
// @since 3.16
type SymbolTag uint32

// Describe options to be used when registered for text document change events.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentChangeRegistrationOptions
type TextDocumentChangeRegistrationOptions struct {
	// How documents are synced to the server.
	SyncKind TextDocumentSyncKind `json:"syncKind"`
	TextDocumentRegistrationOptions
}

// Text document specific client capabilities.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentClientCapabilities
type TextDocumentClientCapabilities struct {
	// Defines which synchronization capabilities the client supports.
	Synchronization *TextDocumentSyncClientCapabilities `json:"synchronization,omitempty"`
	// Defines which filters the client supports.
	//
	// @since 3.18.0
	Filters *TextDocumentFilterClientCapabilities `json:"filters,omitempty"`
	// Capabilities specific to the `textDocument/completion` request.
	Completion CompletionClientCapabilities `json:"completion,omitempty"`
	// Capabilities specific to the `textDocument/hover` request.
	Hover *HoverClientCapabilities `json:"hover,omitempty"`
	// Capabilities specific to the `textDocument/signatureHelp` request.
	SignatureHelp *SignatureHelpClientCapabilities `json:"signatureHelp,omitempty"`
	// Capabilities specific to the `textDocument/declaration` request.
	//
	// @since 3.14.0
	Declaration *DeclarationClientCapabilities `json:"declaration,omitempty"`
	// Capabilities specific to the `textDocument/definition` request.
	Definition *DefinitionClientCapabilities `json:"definition,omitempty"`
	// Capabilities specific to the `textDocument/typeDefinition` request.
	//
	// @since 3.6.0
	TypeDefinition *TypeDefinitionClientCapabilities `json:"typeDefinition,omitempty"`
	// Capabilities specific to the `textDocument/implementation` request.
	//
	// @since 3.6.0
	Implementation *ImplementationClientCapabilities `json:"implementation,omitempty"`
	// Capabilities specific to the `textDocument/references` request.
	References *ReferenceClientCapabilities `json:"references,omitempty"`
	// Capabilities specific to the `textDocument/documentHighlight` request.
	DocumentHighlight *DocumentHighlightClientCapabilities `json:"documentHighlight,omitempty"`
	// Capabilities specific to the `textDocument/documentSymbol` request.
	DocumentSymbol DocumentSymbolClientCapabilities `json:"documentSymbol,omitempty"`
	// Capabilities specific to the `textDocument/codeAction` request.
	CodeAction CodeActionClientCapabilities `json:"codeAction,omitempty"`
	// Capabilities specific to the `textDocument/codeLens` request.
	CodeLens *CodeLensClientCapabilities `json:"codeLens,omitempty"`
	// Capabilities specific to the `textDocument/documentLink` request.
	DocumentLink *DocumentLinkClientCapabilities `json:"documentLink,omitempty"`
	// Capabilities specific to the `textDocument/documentColor` and the
	// `textDocument/colorPresentation` request.
	//
	// @since 3.6.0
	ColorProvider *DocumentColorClientCapabilities `json:"colorProvider,omitempty"`
	// Capabilities specific to the `textDocument/formatting` request.
	Formatting *DocumentFormattingClientCapabilities `json:"formatting,omitempty"`
	// Capabilities specific to the `textDocument/rangeFormatting` request.
	RangeFormatting *DocumentRangeFormattingClientCapabilities `json:"rangeFormatting,omitempty"`
	// Capabilities specific to the `textDocument/onTypeFormatting` request.
	OnTypeFormatting *DocumentOnTypeFormattingClientCapabilities `json:"onTypeFormatting,omitempty"`
	// Capabilities specific to the `textDocument/rename` request.
	Rename *RenameClientCapabilities `json:"rename,omitempty"`
	// Capabilities specific to the `textDocument/foldingRange` request.
	//
	// @since 3.10.0
	FoldingRange *FoldingRangeClientCapabilities `json:"foldingRange,omitempty"`
	// Capabilities specific to the `textDocument/selectionRange` request.
	//
	// @since 3.15.0
	SelectionRange *SelectionRangeClientCapabilities `json:"selectionRange,omitempty"`
	// Capabilities specific to the `textDocument/publishDiagnostics` notification.
	PublishDiagnostics PublishDiagnosticsClientCapabilities `json:"publishDiagnostics,omitempty"`
	// Capabilities specific to the various call hierarchy requests.
	//
	// @since 3.16.0
	CallHierarchy *CallHierarchyClientCapabilities `json:"callHierarchy,omitempty"`
	// Capabilities specific to the various semantic token request.
	//
	// @since 3.16.0
	SemanticTokens SemanticTokensClientCapabilities `json:"semanticTokens,omitempty"`
	// Capabilities specific to the `textDocument/linkedEditingRange` request.
	//
	// @since 3.16.0
	LinkedEditingRange *LinkedEditingRangeClientCapabilities `json:"linkedEditingRange,omitempty"`
	// Client capabilities specific to the `textDocument/moniker` request.
	//
	// @since 3.16.0
	Moniker *MonikerClientCapabilities `json:"moniker,omitempty"`
	// Capabilities specific to the various type hierarchy requests.
	//
	// @since 3.17.0
	TypeHierarchy *TypeHierarchyClientCapabilities `json:"typeHierarchy,omitempty"`
	// Capabilities specific to the `textDocument/inlineValue` request.
	//
	// @since 3.17.0
	InlineValue *InlineValueClientCapabilities `json:"inlineValue,omitempty"`
	// Capabilities specific to the `textDocument/inlayHint` request.
	//
	// @since 3.17.0
	InlayHint *InlayHintClientCapabilities `json:"inlayHint,omitempty"`
	// Capabilities specific to the diagnostic pull model.
	//
	// @since 3.17.0
	Diagnostic *DiagnosticClientCapabilities `json:"diagnostic,omitempty"`
	// Client capabilities specific to inline completions.
	//
	// @since 3.18.0
	// @proposed
	InlineCompletion *InlineCompletionClientCapabilities `json:"inlineCompletion,omitempty"`
}

// An event describing a change to a text document. If only a text is provided
// it is considered to be the full content of the document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentChangeEvent
type TextDocumentContentChangeEvent = TextDocumentContentChangePartial // (alias)
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentChangePartial
type TextDocumentContentChangePartial struct {
	// The range of the document that changed.
	Range *Range `json:"range,omitempty"`
	// The optional length of the range that got replaced.
	//
	// @deprecated use range instead.
	RangeLength *uint32 `json:"rangeLength,omitempty"`
	// The new text for the provided range.
	Text string `json:"text"`
}

// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentChangeWholeDocument
type TextDocumentContentChangeWholeDocument struct {
	// The new text of the whole document.
	Text string `json:"text"`
}

// Client capabilities for a text document content provider.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentClientCapabilities
type TextDocumentContentClientCapabilities struct {
	// Text document content provider supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// Text document content provider options.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentOptions
type TextDocumentContentOptions struct {
	// The schemes for which the server provides content.
	Schemes []string `json:"schemes"`
}

// Parameters for the `workspace/textDocumentContent` request.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentParams
type TextDocumentContentParams struct {
	// The uri of the text document.
	URI DocumentURI `json:"uri"`
}

// Parameters for the `workspace/textDocumentContent/refresh` request.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentRefreshParams
type TextDocumentContentRefreshParams struct {
	// The uri of the text document to refresh.
	URI DocumentURI `json:"uri"`
}

// Text document content provider registration options.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentRegistrationOptions
type TextDocumentContentRegistrationOptions struct {
	TextDocumentContentOptions
	StaticRegistrationOptions
}

// Result of the `workspace/textDocumentContent` request.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentContentResult
type TextDocumentContentResult struct {
	// The text content of the text document. Please note, that the content of
	// any subsequent open notifications for the text document might differ
	// from the returned content due to whitespace and line ending
	// normalizations done on the client
	Text string `json:"text"`
}

// Describes textual changes on a text document. A TextDocumentEdit describes all changes
// on a document version Si and after they are applied move the document to version Si+1.
// So the creator of a TextDocumentEdit doesn't need to sort the array of edits or do any
// kind of ordering. However the edits must be non overlapping.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentEdit
type TextDocumentEdit struct {
	// The text document to change.
	TextDocument OptionalVersionedTextDocumentIdentifier `json:"textDocument"`
	// The edits to be applied.
	//
	// @since 3.16.0 - support for AnnotatedTextEdit. This is guarded using a
	// client capability.
	//
	// @since 3.18.0 - support for SnippetTextEdit. This is guarded using a
	// client capability.
	Edits []Or_TextDocumentEdit_edits_Elem `json:"edits"`
}

// A document filter denotes a document by different properties like
// the {@link TextDocument.languageId language}, the {@link Uri.scheme scheme} of
// its resource, or a glob-pattern that is applied to the {@link TextDocument.fileName path}.
//
// Glob patterns can have the following syntax:
//
//   - `*` to match one or more characters in a path segment
//   - `?` to match on one character in a path segment
//   - `**` to match any number of path segments, including none
//   - `{}` to group sub patterns into an OR expression. (e.g. `**​/*.{ts,js}` matches all TypeScript and JavaScript files)
//   - `[]` to declare a range of characters to match in a path segment (e.g., `example.[0-9]` to match on `example.0`, `example.1`, …)
//   - `[!...]` to negate a range of characters to match in a path segment (e.g., `example.[!0-9]` to match on `example.a`, `example.b`, but not `example.0`)
//
// @sample A language filter that applies to typescript files on disk: `{ language: 'typescript', scheme: 'file' }`
// @sample A language filter that applies to all package.json paths: `{ language: 'json', pattern: '**package.json' }`
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentFilter
type TextDocumentFilter = Or_TextDocumentFilter // (alias)
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentFilterClientCapabilities
type TextDocumentFilterClientCapabilities struct {
	// The client supports Relative Patterns.
	//
	// @since 3.18.0
	RelativePatternSupport bool `json:"relativePatternSupport,omitempty"`
}

// A document filter where `language` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentFilterLanguage
type TextDocumentFilterLanguage struct {
	// A language id, like `typescript`.
	Language string `json:"language"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme,omitempty"`
	// A glob pattern, like **​/*.{ts,js}. See TextDocumentFilter for examples.
	//
	// @since 3.18.0 - support for relative patterns. Whether clients support
	// relative patterns depends on the client capability
	// `textDocuments.filters.relativePatternSupport`.
	Pattern *GlobPattern `json:"pattern,omitempty"`
}

// A document filter where `pattern` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentFilterPattern
type TextDocumentFilterPattern struct {
	// A language id, like `typescript`.
	Language string `json:"language,omitempty"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme,omitempty"`
	// A glob pattern, like **​/*.{ts,js}. See TextDocumentFilter for examples.
	//
	// @since 3.18.0 - support for relative patterns. Whether clients support
	// relative patterns depends on the client capability
	// `textDocuments.filters.relativePatternSupport`.
	Pattern GlobPattern `json:"pattern"`
}

// A document filter where `scheme` is required field.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentFilterScheme
type TextDocumentFilterScheme struct {
	// A language id, like `typescript`.
	Language string `json:"language,omitempty"`
	// A Uri {@link Uri.scheme scheme}, like `file` or `untitled`.
	Scheme string `json:"scheme"`
	// A glob pattern, like **​/*.{ts,js}. See TextDocumentFilter for examples.
	//
	// @since 3.18.0 - support for relative patterns. Whether clients support
	// relative patterns depends on the client capability
	// `textDocuments.filters.relativePatternSupport`.
	Pattern *GlobPattern `json:"pattern,omitempty"`
}

// A literal to identify a text document in the client.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentIdentifier
type TextDocumentIdentifier struct {
	// The text document's uri.
	URI DocumentURI `json:"uri"`
}

// An item to transfer a text document from the client to the
// server.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentItem
type TextDocumentItem struct {
	// The text document's uri.
	URI DocumentURI `json:"uri"`
	// The text document's language identifier.
	LanguageID LanguageKind `json:"languageId"`
	// The version number of this document (it will increase after each
	// change, including undo/redo).
	Version int32 `json:"version"`
	// The content of the opened text document.
	Text string `json:"text"`
}

// A parameter literal used in requests to pass a text document and a position inside that
// document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentPositionParams
type TextDocumentPositionParams struct {
	// The text document.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The position inside the text document.
	//
	// Deprecated: gopls should use [TextDocumentPositionParams.Range] instead.
	Position Position `json:"position"`
	// Range is an optional field representing the user's text selection in the document.
	// If provided, the Position must be contained within this range.
	//
	// Note: This is a non-standard protocol extension. See microsoft/language-server-protocol#377.
	Range Range `json:"range"`
}

// General text document registration options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentRegistrationOptions
type TextDocumentRegistrationOptions struct {
	// A document selector to identify the scope of the registration. If set to null
	// the document selector provided on the client side will be used.
	DocumentSelector DocumentSelector `json:"documentSelector"`
}

// Represents reasons why a text document is saved.
type TextDocumentSaveReason uint32

// Save registration options.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentSaveRegistrationOptions
type TextDocumentSaveRegistrationOptions struct {
	TextDocumentRegistrationOptions
	SaveOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentSyncClientCapabilities
type TextDocumentSyncClientCapabilities struct {
	// Whether text document synchronization supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports sending will save notifications.
	WillSave bool `json:"willSave,omitempty"`
	// The client supports sending a will save request and
	// waits for a response providing text edits which will
	// be applied to the document before it is saved.
	WillSaveWaitUntil bool `json:"willSaveWaitUntil,omitempty"`
	// The client supports did save notifications.
	DidSave bool `json:"didSave,omitempty"`
}

// Defines how the host (editor) should sync
// document changes to the language server.
type TextDocumentSyncKind uint32

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocumentSyncOptions
type TextDocumentSyncOptions struct {
	// Open and close notifications are sent to the server. If omitted open close notification should not
	// be sent.
	OpenClose bool `json:"openClose,omitempty"`
	// Change notifications are sent to the server. See TextDocumentSyncKind.None, TextDocumentSyncKind.Full
	// and TextDocumentSyncKind.Incremental. If omitted it defaults to TextDocumentSyncKind.None.
	Change TextDocumentSyncKind `json:"change,omitempty"`
	// If present will save notifications are sent to the server. If omitted the notification should not be
	// sent.
	WillSave bool `json:"willSave,omitempty"`
	// If present will save wait until requests are sent to the server. If omitted the request should not be
	// sent.
	WillSaveWaitUntil bool `json:"willSaveWaitUntil,omitempty"`
	// If present save notifications are sent to the server. If omitted the notification should not be
	// sent.
	Save *SaveOptions `json:"save,omitempty"`
}

// A text edit applicable to a text document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textEdit
type TextEdit struct {
	// The range of the text document to be manipulated. To insert
	// text into a document create a range where start === end.
	Range Range `json:"range"`
	// The string to be inserted. For delete operations use an
	// empty string.
	NewText string `json:"newText"`
}
type TokenFormat string
type TraceValue string

// Since 3.6.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeDefinitionClientCapabilities
type TypeDefinitionClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `TypeDefinitionRegistrationOptions` return value
	// for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// The client supports additional metadata in the form of definition links.
	//
	// Since 3.14.0
	LinkSupport bool `json:"linkSupport,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeDefinitionOptions
type TypeDefinitionOptions struct {
	WorkDoneProgressOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeDefinitionParams
type TypeDefinitionParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
	PartialResultParams
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeDefinitionRegistrationOptions
type TypeDefinitionRegistrationOptions struct {
	TextDocumentRegistrationOptions
	TypeDefinitionOptions
	StaticRegistrationOptions
}

// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyClientCapabilities
type TypeHierarchyClientCapabilities struct {
	// Whether implementation supports dynamic registration. If this is set to `true`
	// the client supports the new `(TextDocumentRegistrationOptions & StaticRegistrationOptions)`
	// return value for the corresponding server capability as well.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
}

// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyItem
type TypeHierarchyItem struct {
	// The name of this item.
	Name string `json:"name"`
	// The kind of this item.
	Kind SymbolKind `json:"kind"`
	// Tags for this item.
	Tags []SymbolTag `json:"tags,omitempty"`
	// More detail for this item, e.g. the signature of a function.
	Detail string `json:"detail,omitempty"`
	// The resource identifier of this item.
	URI DocumentURI `json:"uri"`
	// The range enclosing this symbol not including leading/trailing whitespace
	// but everything else, e.g. comments and code.
	Range Range `json:"range"`
	// The range that should be selected and revealed when this symbol is being
	// picked, e.g. the name of a function. Must be contained by the
	// {@link TypeHierarchyItem.range `range`}.
	SelectionRange Range `json:"selectionRange"`
	// A data entry field that is preserved between a type hierarchy prepare and
	// supertypes or subtypes requests. It could also be used to identify the
	// type hierarchy in the server, helping improve the performance on
	// resolving supertypes and subtypes.
	Data any `json:"data,omitempty"`
}

// Type hierarchy options used during static registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyOptions
type TypeHierarchyOptions struct {
	WorkDoneProgressOptions
}

// The parameter of a `textDocument/prepareTypeHierarchy` request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyPrepareParams
type TypeHierarchyPrepareParams struct {
	TextDocumentPositionParams
	WorkDoneProgressParams
}

// Type hierarchy options used during static or dynamic registration.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchyRegistrationOptions
type TypeHierarchyRegistrationOptions struct {
	TextDocumentRegistrationOptions
	TypeHierarchyOptions
	StaticRegistrationOptions
}

// The parameter of a `typeHierarchy/subtypes` request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchySubtypesParams
type TypeHierarchySubtypesParams struct {
	Item TypeHierarchyItem `json:"item"`
	WorkDoneProgressParams
	PartialResultParams
}

// The parameter of a `typeHierarchy/supertypes` request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchySupertypesParams
type TypeHierarchySupertypesParams struct {
	Item TypeHierarchyItem `json:"item"`
	WorkDoneProgressParams
	PartialResultParams
}

// created for Tuple
type UIntCommaUInt struct {
	Fld0 uint32 `json:"fld0"`
	Fld1 uint32 `json:"fld1"`
}

// A diagnostic report indicating that the last returned
// report is still accurate.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#unchangedDocumentDiagnosticReport
type UnchangedDocumentDiagnosticReport struct {
	// A document diagnostic report indicating
	// no changes to the last result. A server can
	// only return `unchanged` if result ids are
	// provided.
	Kind string `json:"kind"`
	// A result id which will be sent on the next
	// diagnostic request for the same document.
	ResultID string `json:"resultId"`
}

// Moniker uniqueness level to define scope of the moniker.
//
// @since 3.16.0
type UniquenessLevel string

// General parameters to unregister a request or notification.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#unregistration
type Unregistration struct {
	// The id used to unregister the request or notification. Usually an id
	// provided during the register request.
	ID string `json:"id"`
	// The method to unregister for.
	Method string `json:"method"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#unregistrationParams
type UnregistrationParams struct {
	Unregisterations []Unregistration `json:"unregisterations"`
}

// A versioned notebook document identifier.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#versionedNotebookDocumentIdentifier
type VersionedNotebookDocumentIdentifier struct {
	// The version number of this notebook document.
	Version int32 `json:"version"`
	// The notebook document's uri.
	URI URI `json:"uri"`
}

// A text document identifier to denote a specific version of a text document.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#versionedTextDocumentIdentifier
type VersionedTextDocumentIdentifier struct {
	// The version number of this document.
	Version int32 `json:"version"`
	TextDocumentIdentifier
}
type WatchKind = uint32 // The parameters sent in a will save text document notification.
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#willSaveTextDocumentParams
type WillSaveTextDocumentParams struct {
	// The document that will be saved.
	TextDocument TextDocumentIdentifier `json:"textDocument"`
	// The 'TextDocumentSaveReason'.
	Reason TextDocumentSaveReason `json:"reason"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#windowClientCapabilities
type WindowClientCapabilities struct {
	// It indicates whether the client supports server initiated
	// progress using the `window/workDoneProgress/create` request.
	//
	// The capability also controls Whether client supports handling
	// of progress notifications. If set servers are allowed to report a
	// `workDoneProgress` property in the request specific server
	// capabilities.
	//
	// @since 3.15.0
	WorkDoneProgress bool `json:"workDoneProgress,omitempty"`
	// Capabilities specific to the showMessage request.
	//
	// @since 3.16.0
	ShowMessage *ShowMessageRequestClientCapabilities `json:"showMessage,omitempty"`
	// Capabilities specific to the showDocument request.
	//
	// @since 3.16.0
	ShowDocument *ShowDocumentClientCapabilities `json:"showDocument,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressBegin
type WorkDoneProgressBegin struct {
	Kind string `json:"kind"`
	// Mandatory title of the progress operation. Used to briefly inform about
	// the kind of operation being performed.
	//
	// Examples: "Indexing" or "Linking dependencies".
	Title string `json:"title"`
	// Controls if a cancel button should show to allow the user to cancel the
	// long running operation. Clients that don't support cancellation are allowed
	// to ignore the setting.
	Cancellable bool `json:"cancellable,omitempty"`
	// Optional, more detailed associated progress message. Contains
	// complementary information to the `title`.
	//
	// Examples: "3/25 files", "project/src/module2", "node_modules/some_dep".
	// If unset, the previous progress message (if any) is still valid.
	Message string `json:"message,omitempty"`
	// Optional progress percentage to display (value 100 is considered 100%).
	// If not provided infinite progress is assumed and clients are allowed
	// to ignore the `percentage` value in subsequent in report notifications.
	//
	// The value should be steadily rising. Clients are free to ignore values
	// that are not following this rule. The value range is [0, 100].
	Percentage *uint32 `json:"percentage,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressCancelParams
type WorkDoneProgressCancelParams struct {
	// The token to be used to report progress.
	Token ProgressToken `json:"token"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressCreateParams
type WorkDoneProgressCreateParams struct {
	// The token to be used to report progress.
	Token ProgressToken `json:"token"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressEnd
type WorkDoneProgressEnd struct {
	Kind string `json:"kind"`
	// Optional, a final message indicating to for example indicate the outcome
	// of the operation.
	Message string `json:"message,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressOptions
type WorkDoneProgressOptions struct {
	WorkDoneProgress bool `json:"workDoneProgress,omitempty"`
}

// created for And
type WorkDoneProgressOptionsAndTextDocumentRegistrationOptions struct {
	WorkDoneProgressOptions
	TextDocumentRegistrationOptions
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressParams
type WorkDoneProgressParams struct {
	// An optional token that a server can use to report work done progress.
	WorkDoneToken ProgressToken `json:"workDoneToken,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workDoneProgressReport
type WorkDoneProgressReport struct {
	Kind string `json:"kind"`
	// Controls enablement state of a cancel button.
	//
	// Clients that don't support cancellation or don't support controlling the button's
	// enablement state are allowed to ignore the property.
	Cancellable bool `json:"cancellable,omitempty"`
	// Optional, more detailed associated progress message. Contains
	// complementary information to the `title`.
	//
	// Examples: "3/25 files", "project/src/module2", "node_modules/some_dep".
	// If unset, the previous progress message (if any) is still valid.
	Message string `json:"message,omitempty"`
	// Optional progress percentage to display (value 100 is considered 100%).
	// If not provided infinite progress is assumed and clients are allowed
	// to ignore the `percentage` value in subsequent in report notifications.
	//
	// The value should be steadily rising. Clients are free to ignore values
	// that are not following this rule. The value range is [0, 100]
	Percentage *uint32 `json:"percentage,omitempty"`
}

// Workspace specific client capabilities.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceClientCapabilities
type WorkspaceClientCapabilities struct {
	// The client supports applying batch edits
	// to the workspace by supporting the request
	// 'workspace/applyEdit'
	ApplyEdit bool `json:"applyEdit,omitempty"`
	// Capabilities specific to `WorkspaceEdit`s.
	WorkspaceEdit *WorkspaceEditClientCapabilities `json:"workspaceEdit,omitempty"`
	// Capabilities specific to the `workspace/didChangeConfiguration` notification.
	DidChangeConfiguration DidChangeConfigurationClientCapabilities `json:"didChangeConfiguration,omitempty"`
	// Capabilities specific to the `workspace/didChangeWatchedFiles` notification.
	DidChangeWatchedFiles DidChangeWatchedFilesClientCapabilities `json:"didChangeWatchedFiles,omitempty"`
	// Capabilities specific to the `workspace/symbol` request.
	Symbol *WorkspaceSymbolClientCapabilities `json:"symbol,omitempty"`
	// Capabilities specific to the `workspace/executeCommand` request.
	ExecuteCommand *ExecuteCommandClientCapabilities `json:"executeCommand,omitempty"`
	// The client has support for workspace folders.
	//
	// @since 3.6.0
	WorkspaceFolders bool `json:"workspaceFolders,omitempty"`
	// The client supports `workspace/configuration` requests.
	//
	// @since 3.6.0
	Configuration bool `json:"configuration,omitempty"`
	// Capabilities specific to the semantic token requests scoped to the
	// workspace.
	//
	// @since 3.16.0.
	SemanticTokens *SemanticTokensWorkspaceClientCapabilities `json:"semanticTokens,omitempty"`
	// Capabilities specific to the code lens requests scoped to the
	// workspace.
	//
	// @since 3.16.0.
	CodeLens *CodeLensWorkspaceClientCapabilities `json:"codeLens,omitempty"`
	// The client has support for file notifications/requests for user operations on files.
	//
	// Since 3.16.0
	FileOperations *FileOperationClientCapabilities `json:"fileOperations,omitempty"`
	// Capabilities specific to the inline values requests scoped to the
	// workspace.
	//
	// @since 3.17.0.
	InlineValue *InlineValueWorkspaceClientCapabilities `json:"inlineValue,omitempty"`
	// Capabilities specific to the inlay hint requests scoped to the
	// workspace.
	//
	// @since 3.17.0.
	InlayHint *InlayHintWorkspaceClientCapabilities `json:"inlayHint,omitempty"`
	// Capabilities specific to the diagnostic requests scoped to the
	// workspace.
	//
	// @since 3.17.0.
	Diagnostics *DiagnosticWorkspaceClientCapabilities `json:"diagnostics,omitempty"`
	// Capabilities specific to the folding range requests scoped to the workspace.
	//
	// @since 3.18.0
	// @proposed
	FoldingRange *FoldingRangeWorkspaceClientCapabilities `json:"foldingRange,omitempty"`
	// Capabilities specific to the `workspace/textDocumentContent` request.
	//
	// @since 3.18.0
	// @proposed
	TextDocumentContent *TextDocumentContentClientCapabilities `json:"textDocumentContent,omitempty"`
}

// Parameters of the workspace diagnostic request.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceDiagnosticParams
type WorkspaceDiagnosticParams struct {
	// The additional identifier provided during registration.
	Identifier string `json:"identifier,omitempty"`
	// The currently known diagnostic reports with their
	// previous result ids.
	PreviousResultIds []PreviousResultID `json:"previousResultIds"`
	WorkDoneProgressParams
	PartialResultParams
}

// A workspace diagnostic report.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceDiagnosticReport
type WorkspaceDiagnosticReport struct {
	Items []WorkspaceDocumentDiagnosticReport `json:"items"`
}

// A partial result for a workspace diagnostic report.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceDiagnosticReportPartialResult
type WorkspaceDiagnosticReportPartialResult struct {
	Items []WorkspaceDocumentDiagnosticReport `json:"items"`
}

// A workspace diagnostic document report.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceDocumentDiagnosticReport
type WorkspaceDocumentDiagnosticReport = Or_WorkspaceDocumentDiagnosticReport // (alias)
// A workspace edit represents changes to many resources managed in the workspace. The edit
// should either provide `changes` or `documentChanges`. If documentChanges are present
// they are preferred over `changes` if the client can handle versioned document edits.
//
// Since version 3.13.0 a workspace edit can contain resource operations as well. If resource
// operations are present clients need to execute the operations in the order in which they
// are provided. So a workspace edit for example can consist of the following two changes:
// (1) a create file a.txt and (2) a text document edit which insert text into file a.txt.
//
// An invalid sequence (e.g. (1) delete file a.txt and (2) insert text into file a.txt) will
// cause failure of the operation. How the client recovers from the failure is described by
// the client capability: `workspace.workspaceEdit.failureHandling`
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceEdit
type WorkspaceEdit struct {
	// Holds changes to existing resources.
	Changes map[DocumentURI][]TextEdit `json:"changes,omitempty"`
	// Depending on the client capability `workspace.workspaceEdit.resourceOperations` document changes
	// are either an array of `TextDocumentEdit`s to express changes to n different text documents
	// where each text document edit addresses a specific version of a text document. Or it can contain
	// above `TextDocumentEdit`s mixed with create, rename and delete file / folder operations.
	//
	// Whether a client supports versioned document edits is expressed via
	// `workspace.workspaceEdit.documentChanges` client capability.
	//
	// If a client neither supports `documentChanges` nor `workspace.workspaceEdit.resourceOperations` then
	// only plain `TextEdit`s using the `changes` property are supported.
	DocumentChanges []DocumentChange `json:"documentChanges,omitempty"`
	// A map of change annotations that can be referenced in `AnnotatedTextEdit`s or create, rename and
	// delete file / folder operations.
	//
	// Whether clients honor this property depends on the client capability `workspace.changeAnnotationSupport`.
	//
	// @since 3.16.0
	ChangeAnnotations map[ChangeAnnotationIdentifier]ChangeAnnotation `json:"changeAnnotations,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceEditClientCapabilities
type WorkspaceEditClientCapabilities struct {
	// The client supports versioned document changes in `WorkspaceEdit`s
	DocumentChanges bool `json:"documentChanges,omitempty"`
	// The resource operations the client supports. Clients should at least
	// support 'create', 'rename' and 'delete' files and folders.
	//
	// @since 3.13.0
	ResourceOperations []ResourceOperationKind `json:"resourceOperations,omitempty"`
	// The failure handling strategy of a client if applying the workspace edit
	// fails.
	//
	// @since 3.13.0
	FailureHandling *FailureHandlingKind `json:"failureHandling,omitempty"`
	// Whether the client normalizes line endings to the client specific
	// setting.
	// If set to `true` the client will normalize line ending characters
	// in a workspace edit to the client-specified new line
	// character.
	//
	// @since 3.16.0
	NormalizesLineEndings bool `json:"normalizesLineEndings,omitempty"`
	// Whether the client in general supports change annotations on text edits,
	// create file, rename file and delete file changes.
	//
	// @since 3.16.0
	ChangeAnnotationSupport *ChangeAnnotationsSupportOptions `json:"changeAnnotationSupport,omitempty"`
	// Whether the client supports `WorkspaceEditMetadata` in `WorkspaceEdit`s.
	//
	// @since 3.18.0
	// @proposed
	MetadataSupport bool `json:"metadataSupport,omitempty"`
	// Whether the client supports snippets as text edits.
	//
	// @since 3.18.0
	// @proposed
	SnippetEditSupport bool `json:"snippetEditSupport,omitempty"`
}

// Additional data about a workspace edit.
//
// @since 3.18.0
// @proposed
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceEditMetadata
type WorkspaceEditMetadata struct {
	// Signal to the editor that this edit is a refactoring.
	IsRefactoring bool `json:"isRefactoring,omitempty"`
}

// A workspace folder inside a client.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFolder
type WorkspaceFolder struct {
	// The associated URI for this workspace folder.
	URI URI `json:"uri"`
	// The name of the workspace folder. Used to refer to this
	// workspace folder in the user interface.
	Name string `json:"name"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFoldersServerCapabilities
type WorkspaceFolders5Gn struct {
	// The server has support for workspace folders
	Supported bool `json:"supported,omitempty"`
	// Whether the server wants to receive workspace folder
	// change notifications.
	//
	// If a string is provided the string is treated as an ID
	// under which the notification is registered on the client
	// side. The ID can be used to unregister for these events
	// using the `client/unregisterCapability` request.
	ChangeNotifications string `json:"changeNotifications,omitempty"`
}

// The workspace folder change event.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFoldersChangeEvent
type WorkspaceFoldersChangeEvent struct {
	// The array of added workspace folders
	Added []WorkspaceFolder `json:"added"`
	// The array of the removed workspace folders
	Removed []WorkspaceFolder `json:"removed"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFoldersInitializeParams
type WorkspaceFoldersInitializeParams struct {
	// The workspace folders configured in the client when the server starts.
	//
	// This property is only available if the client supports workspace folders.
	// It can be `null` if the client supports workspace folders but none are
	// configured.
	//
	// @since 3.6.0
	WorkspaceFolders []WorkspaceFolder `json:"workspaceFolders,omitempty"`
}

// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFoldersServerCapabilities
type WorkspaceFoldersServerCapabilities struct {
	// The server has support for workspace folders
	Supported bool `json:"supported,omitempty"`
	// Whether the server wants to receive workspace folder
	// change notifications.
	//
	// If a string is provided the string is treated as an ID
	// under which the notification is registered on the client
	// side. The ID can be used to unregister for these events
	// using the `client/unregisterCapability` request.
	ChangeNotifications string `json:"changeNotifications,omitempty"`
}

// A full document diagnostic report for a workspace diagnostic result.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceFullDocumentDiagnosticReport
type WorkspaceFullDocumentDiagnosticReport struct {
	// The URI for which diagnostic information is reported.
	URI DocumentURI `json:"uri"`
	// The version number for which the diagnostics are reported.
	// If the document is not marked as open `null` can be provided.
	Version int32 `json:"version"`
	FullDocumentDiagnosticReport
}

// Defines workspace specific capabilities of the server.
//
// @since 3.18.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceOptions
type WorkspaceOptions struct {
	// The server supports workspace folder.
	//
	// @since 3.6.0
	WorkspaceFolders *WorkspaceFolders5Gn `json:"workspaceFolders,omitempty"`
	// The server is interested in notifications/requests for operations on files.
	//
	// @since 3.16.0
	FileOperations *FileOperationOptions `json:"fileOperations,omitempty"`
	// The server supports the `workspace/textDocumentContent` request.
	//
	// @since 3.18.0
	// @proposed
	TextDocumentContent *Or_WorkspaceOptions_textDocumentContent `json:"textDocumentContent,omitempty"`
}

// A special workspace symbol that supports locations without a range.
//
// See also SymbolInformation.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbol
type WorkspaceSymbol struct {
	// The location of the symbol. Whether a server is allowed to
	// return a location without a range depends on the client
	// capability `workspace.symbol.resolveSupport`.
	//
	// See SymbolInformation#location for more details.
	Location OrPLocation_workspace_symbol `json:"location"`
	// A data entry field that is preserved on a workspace symbol between a
	// workspace symbol request and a workspace symbol resolve request.
	Data any `json:"data,omitempty"`
	BaseSymbolInformation
}

// Client capabilities for a {@link WorkspaceSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbolClientCapabilities
type WorkspaceSymbolClientCapabilities struct {
	// Symbol request supports dynamic registration.
	DynamicRegistration bool `json:"dynamicRegistration,omitempty"`
	// Specific capabilities for the `SymbolKind` in the `workspace/symbol` request.
	SymbolKind *ClientSymbolKindOptions `json:"symbolKind,omitempty"`
	// The client supports tags on `SymbolInformation`.
	// Clients supporting tags have to handle unknown tags gracefully.
	//
	// @since 3.16.0
	TagSupport *ClientSymbolTagOptions `json:"tagSupport,omitempty"`
	// The client support partial workspace symbols. The client will send the
	// request `workspaceSymbol/resolve` to the server to resolve additional
	// properties.
	//
	// @since 3.17.0
	ResolveSupport *ClientSymbolResolveOptions `json:"resolveSupport,omitempty"`
}

// Server capabilities for a {@link WorkspaceSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbolOptions
type WorkspaceSymbolOptions struct {
	// The server provides support to resolve additional
	// information for a workspace symbol.
	//
	// @since 3.17.0
	ResolveProvider bool `json:"resolveProvider,omitempty"`
	WorkDoneProgressOptions
}

// The parameters of a {@link WorkspaceSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbolParams
type WorkspaceSymbolParams struct {
	// A query string to filter symbols by. Clients may send an empty
	// string here to request all symbols.
	//
	// The `query`-parameter should be interpreted in a *relaxed way* as editors
	// will apply their own highlighting and scoring on the results. A good rule
	// of thumb is to match case-insensitive and to simply check that the
	// characters of *query* appear in their order in a candidate symbol.
	// Servers shouldn't use prefix, substring, or similar strict matching.
	Query string `json:"query"`
	WorkDoneProgressParams
	PartialResultParams
}

// Registration options for a {@link WorkspaceSymbolRequest}.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbolRegistrationOptions
type WorkspaceSymbolRegistrationOptions struct {
	WorkspaceSymbolOptions
}

// An unchanged document diagnostic report for a workspace diagnostic result.
//
// @since 3.17.0
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceUnchangedDocumentDiagnosticReport
type WorkspaceUnchangedDocumentDiagnosticReport struct {
	// The URI for which diagnostic information is reported.
	URI DocumentURI `json:"uri"`
	// The version number for which the diagnostics are reported.
	// If the document is not marked as open `null` can be provided.
	Version int32 `json:"version"`
	UnchangedDocumentDiagnosticReport
}

// The initialize parameters
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#_InitializeParams
type XInitializeParams struct {
	// The process Id of the parent process that started
	// the server.
	//
	// Is `null` if the process has not been started by another process.
	// If the parent process is not alive then the server should exit.
	ProcessID int32 `json:"processId"`
	// Information about the client
	//
	// @since 3.15.0
	ClientInfo *ClientInfo `json:"clientInfo,omitempty"`
	// The locale the client is currently showing the user interface
	// in. This must not necessarily be the locale of the operating
	// system.
	//
	// Uses IETF language tags as the value's syntax
	// (See https://en.wikipedia.org/wiki/IETF_language_tag)
	//
	// @since 3.16.0
	Locale string `json:"locale,omitempty"`
	// The rootPath of the workspace. Is null
	// if no folder is open.
	//
	// @deprecated in favour of rootUri.
	RootPath string `json:"rootPath,omitempty"`
	// The rootUri of the workspace. Is null if no
	// folder is open. If both `rootPath` and `rootUri` are set
	// `rootUri` wins.
	//
	// @deprecated in favour of workspaceFolders.
	RootURI DocumentURI `json:"rootUri"`
	// The capabilities provided by the client (editor or tool)
	Capabilities ClientCapabilities `json:"capabilities"`
	// User provided initialization options.
	InitializationOptions any `json:"initializationOptions,omitempty"`
	// The initial trace setting. If omitted trace is disabled ('off').
	Trace *TraceValue `json:"trace,omitempty"`
	WorkDoneProgressParams
}

// The initialize parameters
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#_InitializeParams
type _InitializeParams struct {
	// The process Id of the parent process that started
	// the server.
	//
	// Is `null` if the process has not been started by another process.
	// If the parent process is not alive then the server should exit.
	ProcessID int32 `json:"processId"`
	// Information about the client
	//
	// @since 3.15.0
	ClientInfo *ClientInfo `json:"clientInfo,omitempty"`
	// The locale the client is currently showing the user interface
	// in. This must not necessarily be the locale of the operating
	// system.
	//
	// Uses IETF language tags as the value's syntax
	// (See https://en.wikipedia.org/wiki/IETF_language_tag)
	//
	// @since 3.16.0
	Locale string `json:"locale,omitempty"`
	// The rootPath of the workspace. Is null
	// if no folder is open.
	//
	// @deprecated in favour of rootUri.
	RootPath string `json:"rootPath,omitempty"`
	// The rootUri of the workspace. Is null if no
	// folder is open. If both `rootPath` and `rootUri` are set
	// `rootUri` wins.
	//
	// @deprecated in favour of workspaceFolders.
	RootURI DocumentURI `json:"rootUri"`
	// The capabilities provided by the client (editor or tool)
	Capabilities ClientCapabilities `json:"capabilities"`
	// User provided initialization options.
	InitializationOptions any `json:"initializationOptions,omitempty"`
	// The initial trace setting. If omitted trace is disabled ('off').
	Trace *TraceValue `json:"trace,omitempty"`
	WorkDoneProgressParams
}

const (
	// Defines how values from a set of defaults and an individual item will be
	// merged.
	//
	// @since 3.18.0
	// The value from the individual item (if provided and not `null`) will be
	// used instead of the default.
	Replace ApplyKind = 1
	// The value from the item will be merged with the default.
	//
	// The specific rules for mergeing values are defined against each field
	// that supports merging.
	Merge ApplyKind = 2
	// A set of predefined code action kinds
	// Empty kind.
	Empty CodeActionKind = ""
	// Base kind for quickfix actions: 'quickfix'
	QuickFix CodeActionKind = "quickfix"
	// Base kind for refactoring actions: 'refactor'
	Refactor CodeActionKind = "refactor"
	// Base kind for refactoring extraction actions: 'refactor.extract'
	//
	// Example extract actions:
	//
	//
	//  - Extract method
	//  - Extract function
	//  - Extract variable
	//  - Extract interface from class
	//  - ...
	RefactorExtract CodeActionKind = "refactor.extract"
	// Base kind for refactoring inline actions: 'refactor.inline'
	//
	// Example inline actions:
	//
	//
	//  - Inline function
	//  - Inline variable
	//  - Inline constant
	//  - ...
	RefactorInline CodeActionKind = "refactor.inline"
	// Base kind for refactoring move actions: `refactor.move`
	//
	// Example move actions:
	//
	//
	//  - Move a function to a new file
	//  - Move a property between classes
	//  - Move method to base class
	//  - ...
	//
	// @since 3.18.0
	// @proposed
	RefactorMove CodeActionKind = "refactor.move"
	// Base kind for refactoring rewrite actions: 'refactor.rewrite'
	//
	// Example rewrite actions:
	//
	//
	//  - Convert JavaScript function to class
	//  - Add or remove parameter
	//  - Encapsulate field
	//  - Make method static
	//  - Move method to base class
	//  - ...
	RefactorRewrite CodeActionKind = "refactor.rewrite"
	// Base kind for source actions: `source`
	//
	// Source code actions apply to the entire file.
	Source CodeActionKind = "source"
	// Base kind for an organize imports source action: `source.organizeImports`
	SourceOrganizeImports CodeActionKind = "source.organizeImports"
	// Base kind for auto-fix source actions: `source.fixAll`.
	//
	// Fix all actions automatically fix errors that have a clear fix that do not require user input.
	// They should not suppress errors or perform unsafe fixes such as generating new types or classes.
	//
	// @since 3.15.0
	SourceFixAll CodeActionKind = "source.fixAll"
	// Base kind for all code actions applying to the entire notebook's scope. CodeActionKinds using
	// this should always begin with `notebook.`
	//
	// @since 3.18.0
	Notebook CodeActionKind = "notebook"
	// Code action tags are extra annotations that tweak the behavior of a code action.
	//
	// @since 3.18.0 - proposed
	// Marks the code action as LLM-generated.
	LLMGenerated CodeActionTag = 1
	// The reason why code actions were requested.
	//
	// @since 3.17.0
	// Code actions were explicitly requested by the user or by an extension.
	CodeActionInvoked CodeActionTriggerKind = 1
	// Code actions were requested automatically.
	//
	// This typically happens when current selection in a file changes, but can
	// also be triggered when file content changes.
	CodeActionAutomatic CodeActionTriggerKind = 2
	// The kind of a completion entry.
	TextCompletion          CompletionItemKind = 1
	MethodCompletion        CompletionItemKind = 2
	FunctionCompletion      CompletionItemKind = 3
	ConstructorCompletion   CompletionItemKind = 4
	FieldCompletion         CompletionItemKind = 5
	VariableCompletion      CompletionItemKind = 6
	ClassCompletion         CompletionItemKind = 7
	InterfaceCompletion     CompletionItemKind = 8
	ModuleCompletion        CompletionItemKind = 9
	PropertyCompletion      CompletionItemKind = 10
	UnitCompletion          CompletionItemKind = 11
	ValueCompletion         CompletionItemKind = 12
	EnumCompletion          CompletionItemKind = 13
	KeywordCompletion       CompletionItemKind = 14
	SnippetCompletion       CompletionItemKind = 15
	ColorCompletion         CompletionItemKind = 16
	FileCompletion          CompletionItemKind = 17
	ReferenceCompletion     CompletionItemKind = 18
	FolderCompletion        CompletionItemKind = 19
	EnumMemberCompletion    CompletionItemKind = 20
	ConstantCompletion      CompletionItemKind = 21
	StructCompletion        CompletionItemKind = 22
	EventCompletion         CompletionItemKind = 23
	OperatorCompletion      CompletionItemKind = 24
	TypeParameterCompletion CompletionItemKind = 25
	// Completion item tags are extra annotations that tweak the rendering of a completion
	// item.
	//
	// @since 3.15.0
	// Render a completion as obsolete, usually using a strike-out.
	ComplDeprecated CompletionItemTag = 1
	// How a completion was triggered
	// Completion was triggered by typing an identifier (24x7 code
	// complete), manual invocation (e.g Ctrl+Space) or via API.
	Invoked CompletionTriggerKind = 1
	// Completion was triggered by a trigger character specified by
	// the `triggerCharacters` properties of the `CompletionRegistrationOptions`.
	TriggerCharacter CompletionTriggerKind = 2
	// Completion was re-triggered as current completion list is incomplete
	TriggerForIncompleteCompletions CompletionTriggerKind = 3
	// The diagnostic's severity.
	// Reports an error.
	SeverityError DiagnosticSeverity = 1
	// Reports a warning.
	SeverityWarning DiagnosticSeverity = 2
	// Reports an information.
	SeverityInformation DiagnosticSeverity = 3
	// Reports a hint.
	SeverityHint DiagnosticSeverity = 4
	// The diagnostic tags.
	//
	// @since 3.15.0
	// Unused or unnecessary code.
	//
	// Clients are allowed to render diagnostics with this tag faded out instead of having
	// an error squiggle.
	Unnecessary DiagnosticTag = 1
	// Deprecated or obsolete code.
	//
	// Clients are allowed to rendered diagnostics with this tag strike through.
	Deprecated DiagnosticTag = 2
	// The document diagnostic report kinds.
	//
	// @since 3.17.0
	// A diagnostic report with a full
	// set of problems.
	DiagnosticFull DocumentDiagnosticReportKind = "full"
	// A report indicating that the last
	// returned report is still accurate.
	DiagnosticUnchanged DocumentDiagnosticReportKind = "unchanged"
	// A document highlight kind.
	// A textual occurrence.
	Text DocumentHighlightKind = 1
	// Read-access of a symbol, like reading a variable.
	Read DocumentHighlightKind = 2
	// Write-access of a symbol, like writing to a variable.
	Write DocumentHighlightKind = 3
	// Predefined error codes.
	ParseError     ErrorCodes = -32700
	InvalidRequest ErrorCodes = -32600
	MethodNotFound ErrorCodes = -32601
	InvalidParams  ErrorCodes = -32602
	InternalError  ErrorCodes = -32603
	// Error code indicating that a server received a notification or
	// request before the server has received the `initialize` request.
	ServerNotInitialized ErrorCodes = -32002
	UnknownErrorCode     ErrorCodes = -32001
	// Applying the workspace change is simply aborted if one of the changes provided
	// fails. All operations executed before the failing operation stay executed.
	Abort FailureHandlingKind = "abort"
	// All operations are executed transactional. That means they either all
	// succeed or no changes at all are applied to the workspace.
	Transactional FailureHandlingKind = "transactional"
	// If the workspace edit contains only textual file changes they are executed transactional.
	// If resource changes (create, rename or delete file) are part of the change the failure
	// handling strategy is abort.
	TextOnlyTransactional FailureHandlingKind = "textOnlyTransactional"
	// The client tries to undo the operations already executed. But there is no
	// guarantee that this is succeeding.
	Undo FailureHandlingKind = "undo"
	// The file event type
	// The file got created.
	Created FileChangeType = 1
	// The file got changed.
	Changed FileChangeType = 2
	// The file got deleted.
	Deleted FileChangeType = 3
	// A pattern kind describing if a glob pattern matches a file a folder or
	// both.
	//
	// @since 3.16.0
	// The pattern matches a file only.
	FilePattern FileOperationPatternKind = "file"
	// The pattern matches a folder only.
	FolderPattern FileOperationPatternKind = "folder"
	// A set of predefined range kinds.
	// Folding range for a comment
	Comment FoldingRangeKind = "comment"
	// Folding range for an import or include
	Imports FoldingRangeKind = "imports"
	// Folding range for a region (e.g. `#region`)
	Region FoldingRangeKind = "region"
	// Inlay hint kinds.
	//
	// @since 3.17.0
	// An inlay hint that for a type annotation.
	Type InlayHintKind = 1
	// An inlay hint that is for a parameter.
	Parameter InlayHintKind = 2
	// Describes how an {@link InlineCompletionItemProvider inline completion provider} was triggered.
	//
	// @since 3.18.0
	// @proposed
	// Completion was triggered explicitly by a user gesture.
	InlineInvoked InlineCompletionTriggerKind = 1
	// Completion was triggered automatically while editing.
	InlineAutomatic InlineCompletionTriggerKind = 2
	// Defines whether the insert text in a completion item should be interpreted as
	// plain text or a snippet.
	// The primary text to be inserted is treated as a plain string.
	PlainTextTextFormat InsertTextFormat = 1
	// The primary text to be inserted is treated as a snippet.
	//
	// A snippet can define tab stops and placeholders with `$1`, `$2`
	// and `${3:foo}`. `$0` defines the final tab stop, it defaults to
	// the end of the snippet. Placeholders with equal identifiers are linked,
	// that is typing in one will update others too.
	//
	// See also: https://microsoft.github.io/language-server-protocol/specifications/specification-current/#snippet_syntax
	SnippetTextFormat InsertTextFormat = 2
	// How whitespace and indentation is handled during completion
	// item insertion.
	//
	// @since 3.16.0
	// The insertion or replace strings is taken as it is. If the
	// value is multi line the lines below the cursor will be
	// inserted using the indentation defined in the string value.
	// The client will not apply any kind of adjustments to the
	// string.
	AsIs InsertTextMode = 1
	// The editor adjusts leading whitespace of new lines so that
	// they match the indentation up to the cursor of the line for
	// which the item is accepted.
	//
	// Consider a line like this: <2tabs><cursor><3tabs>foo. Accepting a
	// multi line completion item is indented using 2 tabs and all
	// following lines inserted will be indented using 2 tabs as well.
	AdjustIndentation InsertTextMode = 2
	// A request failed but it was syntactically correct, e.g the
	// method name was known and the parameters were valid. The error
	// message should contain human readable information about why
	// the request failed.
	//
	// @since 3.17.0
	RequestFailed LSPErrorCodes = -32803
	// The server cancelled the request. This error code should
	// only be used for requests that explicitly support being
	// server cancellable.
	//
	// @since 3.17.0
	ServerCancelled LSPErrorCodes = -32802
	// The server detected that the content of a document got
	// modified outside normal conditions. A server should
	// NOT send this error code if it detects a content change
	// in it unprocessed messages. The result even computed
	// on an older state might still be useful for the client.
	//
	// If a client decides that a result is not of any use anymore
	// the client should cancel the request.
	ContentModified LSPErrorCodes = -32801
	// The client has canceled a request and a server has detected
	// the cancel.
	RequestCancelled LSPErrorCodes = -32800
	// Predefined Language kinds
	// @since 3.18.0
	LangABAP         LanguageKind = "abap"
	LangWindowsBat   LanguageKind = "bat"
	LangBibTeX       LanguageKind = "bibtex"
	LangClojure      LanguageKind = "clojure"
	LangCoffeescript LanguageKind = "coffeescript"
	LangC            LanguageKind = "c"
	LangCPP          LanguageKind = "cpp"
	LangCSharp       LanguageKind = "csharp"
	LangCSS          LanguageKind = "css"
	// @since 3.18.0
	// @proposed
	LangD LanguageKind = "d"
	// @since 3.18.0
	// @proposed
	LangDelphi          LanguageKind = "pascal"
	LangDiff            LanguageKind = "diff"
	LangDart            LanguageKind = "dart"
	LangDockerfile      LanguageKind = "dockerfile"
	LangElixir          LanguageKind = "elixir"
	LangErlang          LanguageKind = "erlang"
	LangFSharp          LanguageKind = "fsharp"
	LangGitCommit       LanguageKind = "git-commit"
	LangGitRebase       LanguageKind = "rebase"
	LangGo              LanguageKind = "go"
	LangGroovy          LanguageKind = "groovy"
	LangHandlebars      LanguageKind = "handlebars"
	LangHaskell         LanguageKind = "haskell"
	LangHTML            LanguageKind = "html"
	LangIni             LanguageKind = "ini"
	LangJava            LanguageKind = "java"
	LangJavaScript      LanguageKind = "javascript"
	LangJavaScriptReact LanguageKind = "javascriptreact"
	LangJSON            LanguageKind = "json"
	LangLaTeX           LanguageKind = "latex"
	LangLess            LanguageKind = "less"
	LangLua             LanguageKind = "lua"
	LangMakefile        LanguageKind = "makefile"
	LangMarkdown        LanguageKind = "markdown"
	LangObjectiveC      LanguageKind = "objective-c"
	LangObjectiveCPP    LanguageKind = "objective-cpp"
	// @since 3.18.0
	// @proposed
	LangPascal          LanguageKind = "pascal"
	LangPerl            LanguageKind = "perl"
	LangPerl6           LanguageKind = "perl6"
	LangPHP             LanguageKind = "php"
	LangPowershell      LanguageKind = "powershell"
	LangPug             LanguageKind = "jade"
	LangPython          LanguageKind = "python"
	LangR               LanguageKind = "r"
	LangRazor           LanguageKind = "razor"
	LangRuby            LanguageKind = "ruby"
	LangRust            LanguageKind = "rust"
	LangSCSS            LanguageKind = "scss"
	LangSASS            LanguageKind = "sass"
	LangScala           LanguageKind = "scala"
	LangShaderLab       LanguageKind = "shaderlab"
	LangShellScript     LanguageKind = "shellscript"
	LangSQL             LanguageKind = "sql"
	LangSwift           LanguageKind = "swift"
	LangTypeScript      LanguageKind = "typescript"
	LangTypeScriptReact LanguageKind = "typescriptreact"
	LangTeX             LanguageKind = "tex"
	LangVisualBasic     LanguageKind = "vb"
	LangXML             LanguageKind = "xml"
	LangXSL             LanguageKind = "xsl"
	LangYAML            LanguageKind = "yaml"
	// Describes the content type that a client supports in various
	// result literals like `Hover`, `ParameterInfo` or `CompletionItem`.
	//
	// Please note that `MarkupKinds` must not start with a `$`. This kinds
	// are reserved for internal usage.
	// Plain text is supported as a content format
	PlainText MarkupKind = "plaintext"
	// Markdown is supported as a content format
	Markdown MarkupKind = "markdown"
	// The message type
	// An error message.
	Error MessageType = 1
	// A warning message.
	Warning MessageType = 2
	// An information message.
	Info MessageType = 3
	// A log message.
	Log MessageType = 4
	// A debug message.
	//
	// @since 3.18.0
	// @proposed
	Debug MessageType = 5
	// The moniker kind.
	//
	// @since 3.16.0
	// The moniker represent a symbol that is imported into a project
	Import MonikerKind = "import"
	// The moniker represents a symbol that is exported from a project
	Export MonikerKind = "export"
	// The moniker represents a symbol that is local to a project (e.g. a local
	// variable of a function, a class not visible outside the project, ...)
	Local MonikerKind = "local"
	// A notebook cell kind.
	//
	// @since 3.17.0
	// A markup-cell is formatted source that is used for display.
	Markup NotebookCellKind = 1
	// A code-cell is source code.
	Code NotebookCellKind = 2
	// A set of predefined position encoding kinds.
	//
	// @since 3.17.0
	// Character offsets count UTF-8 code units (e.g. bytes).
	UTF8 PositionEncodingKind = "utf-8"
	// Character offsets count UTF-16 code units.
	//
	// This is the default and must always be supported
	// by servers
	UTF16 PositionEncodingKind = "utf-16"
	// Character offsets count UTF-32 code units.
	//
	// Implementation note: these are the same as Unicode codepoints,
	// so this `PositionEncodingKind` may also be used for an
	// encoding-agnostic representation of character offsets.
	UTF32 PositionEncodingKind = "utf-32"
	// The client's default behavior is to select the identifier
	// according the to language's syntax rule.
	Identifier PrepareSupportDefaultBehavior = 1
	// Supports creating new files and folders.
	Create ResourceOperationKind = "create"
	// Supports renaming existing files and folders.
	Rename ResourceOperationKind = "rename"
	// Supports deleting existing files and folders.
	Delete ResourceOperationKind = "delete"
	// A set of predefined token modifiers. This set is not fixed
	// an clients can specify additional token types via the
	// corresponding client capabilities.
	//
	// @since 3.16.0
	ModDeclaration    SemanticTokenModifiers = "declaration"
	ModDefinition     SemanticTokenModifiers = "definition"
	ModReadonly       SemanticTokenModifiers = "readonly"
	ModStatic         SemanticTokenModifiers = "static"
	ModDeprecated     SemanticTokenModifiers = "deprecated"
	ModAbstract       SemanticTokenModifiers = "abstract"
	ModAsync          SemanticTokenModifiers = "async"
	ModModification   SemanticTokenModifiers = "modification"
	ModDocumentation  SemanticTokenModifiers = "documentation"
	ModDefaultLibrary SemanticTokenModifiers = "defaultLibrary"
	// A set of predefined token types. This set is not fixed
	// an clients can specify additional token types via the
	// corresponding client capabilities.
	//
	// @since 3.16.0
	NamespaceType SemanticTokenTypes = "namespace"
	// Represents a generic type. Acts as a fallback for types which can't be mapped to
	// a specific type like class or enum.
	TypeType          SemanticTokenTypes = "type"
	ClassType         SemanticTokenTypes = "class"
	EnumType          SemanticTokenTypes = "enum"
	InterfaceType     SemanticTokenTypes = "interface"
	StructType        SemanticTokenTypes = "struct"
	TypeParameterType SemanticTokenTypes = "typeParameter"
	ParameterType     SemanticTokenTypes = "parameter"
	VariableType      SemanticTokenTypes = "variable"
	PropertyType      SemanticTokenTypes = "property"
	EnumMemberType    SemanticTokenTypes = "enumMember"
	EventType         SemanticTokenTypes = "event"
	FunctionType      SemanticTokenTypes = "function"
	MethodType        SemanticTokenTypes = "method"
	MacroType         SemanticTokenTypes = "macro"
	KeywordType       SemanticTokenTypes = "keyword"
	ModifierType      SemanticTokenTypes = "modifier"
	CommentType       SemanticTokenTypes = "comment"
	StringType        SemanticTokenTypes = "string"
	NumberType        SemanticTokenTypes = "number"
	RegexpType        SemanticTokenTypes = "regexp"
	OperatorType      SemanticTokenTypes = "operator"
	// @since 3.17.0
	DecoratorType SemanticTokenTypes = "decorator"
	// @since 3.18.0
	LabelType SemanticTokenTypes = "label"
	// How a signature help was triggered.
	//
	// @since 3.15.0
	// Signature help was invoked manually by the user or by a command.
	SigInvoked SignatureHelpTriggerKind = 1
	// Signature help was triggered by a trigger character.
	SigTriggerCharacter SignatureHelpTriggerKind = 2
	// Signature help was triggered by the cursor moving or by the document content changing.
	SigContentChange SignatureHelpTriggerKind = 3
	// A symbol kind.
	File          SymbolKind = 1
	Module        SymbolKind = 2
	Namespace     SymbolKind = 3
	Package       SymbolKind = 4
	Class         SymbolKind = 5
	Method        SymbolKind = 6
	Property      SymbolKind = 7
	Field         SymbolKind = 8
	Constructor   SymbolKind = 9
	Enum          SymbolKind = 10
	Interface     SymbolKind = 11
	Function      SymbolKind = 12
	Variable      SymbolKind = 13
	Constant      SymbolKind = 14
	String        SymbolKind = 15
	Number        SymbolKind = 16
	Boolean       SymbolKind = 17
	Array         SymbolKind = 18
	Object        SymbolKind = 19
	Key           SymbolKind = 20
	Null          SymbolKind = 21
	EnumMember    SymbolKind = 22
	Struct        SymbolKind = 23
	Event         SymbolKind = 24
	Operator      SymbolKind = 25
	TypeParameter SymbolKind = 26
	// Symbol tags are extra annotations that tweak the rendering of a symbol.
	//
	// @since 3.16
	// Render a symbol as obsolete, usually using a strike-out.
	DeprecatedSymbol SymbolTag = 1
	// Represents reasons why a text document is saved.
	// Manually triggered, e.g. by the user pressing save, by starting debugging,
	// or by an API call.
	Manual TextDocumentSaveReason = 1
	// Automatic after a delay.
	AfterDelay TextDocumentSaveReason = 2
	// When the editor lost focus.
	FocusOut TextDocumentSaveReason = 3
	// Defines how the host (editor) should sync
	// document changes to the language server.
	// Documents should not be synced at all.
	None TextDocumentSyncKind = 0
	// Documents are synced by always sending the full content
	// of the document.
	Full TextDocumentSyncKind = 1
	// Documents are synced by sending the full content on open.
	// After that only incremental updates to the document are
	// send.
	Incremental TextDocumentSyncKind = 2
	Relative    TokenFormat          = "relative"
	// Turn tracing off.
	Off TraceValue = "off"
	// Trace messages only.
	Messages TraceValue = "messages"
	// Verbose message tracing.
	Verbose TraceValue = "verbose"
	// Moniker uniqueness level to define scope of the moniker.
	//
	// @since 3.16.0
	// The moniker is only unique inside a document
	Document UniquenessLevel = "document"
	// The moniker is unique inside a project for which a dump got created
	Project UniquenessLevel = "project"
	// The moniker is unique inside the group to which a project belongs
	Group UniquenessLevel = "group"
	// The moniker is unique inside the moniker scheme.
	Scheme UniquenessLevel = "scheme"
	// The moniker is globally unique
	Global UniquenessLevel = "global"
	// Interested in create events.
	WatchCreate WatchKind = 1
	// Interested in change events
	WatchChange WatchKind = 2
	// Interested in delete events
	WatchDelete WatchKind = 4
)


================================================
FILE: gopls/internal/protocol/tsserver.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated for LSP. DO NOT EDIT.

package protocol

// Code generated from protocol/metaModel.json at ref release/protocol/3.17.6-next.14 (hash 66a087310eea0d60495ba3578d78f70409c403d9).
// https://github.com/microsoft/vscode-languageserver-node/blob/release/protocol/3.17.6-next.14/protocol/metaModel.json
// LSP metaData.version = 3.17.0.

import (
	"context"
	"encoding/json"
	"fmt"

	"golang.org/x/tools/internal/jsonrpc2"
)

type Server interface {
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#progress
	Progress(context.Context, *ProgressParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#setTrace
	SetTrace(context.Context, *SetTraceParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchy_incomingCalls
	IncomingCalls(context.Context, *CallHierarchyIncomingCallsParams) ([]CallHierarchyIncomingCall, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#callHierarchy_outgoingCalls
	OutgoingCalls(context.Context, *CallHierarchyOutgoingCallsParams) ([]CallHierarchyOutgoingCall, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeAction_resolve
	ResolveCodeAction(context.Context, *CodeAction) (*CodeAction, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#codeLens_resolve
	ResolveCodeLens(context.Context, *CodeLens) (*CodeLens, error)
	// To support microsoft/language-server-protocol#1164, the language server
	// need to read the form with client-supplied answers and either returns an
	// ExecuteCommandParams with errors in the form surfacing the error to the
	// client, or an ExecuteCommandParams with interactive properties empty (e.g
	// formFields, formAnswers) and user information integrated in original
	// properties.
	//
	// The language client may call "command/resolve" if the language server
	// returns an ExecuteCommandParams with errors or try asking the user for
	// completing the form again.
	// The language client may call "command/resolve" multiple times with user
	// filled (re-filled) answers in the form until it obtains an
	// ExecuteCommandParams with interactive properties empty (e.g. formFields,
	// formAnswers). by then the original properties contains all information,
	// the client can call "workspace/executeCommand" with the same param.
	//
	// Standard resolution (e.g., "codeAction/resolve") cannot be used here because
	// it is often triggered eagerly (e.g., for previews), prohibiting interactive
	// forms. "command/resolve" is introduced to handle the interactive flow
	// strictly *after* the user has explicitly indicated intention (e.g., by
	// clicking), making it safe for Code Actions and other refactorings.
	//
	// Note: This is a non-standard protocol extension.
	ResolveCommand(context.Context, *ExecuteCommandParams) (*ExecuteCommandParams, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#completionItem_resolve
	ResolveCompletionItem(context.Context, *CompletionItem) (*CompletionItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#documentLink_resolve
	ResolveDocumentLink(context.Context, *DocumentLink) (*DocumentLink, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#exit
	Exit(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initialize
	Initialize(context.Context, *ParamInitialize) (*InitializeResult, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#initialized
	Initialized(context.Context, *InitializedParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#inlayHint_resolve
	Resolve(context.Context, *InlayHint) (*InlayHint, error)
	// InteractiveListEnum is the request handler for fetching dynamic enum options.
	//
	// This method is called by the client when the user interacts with a
	// FormFieldTypeLazyEnum field (e.g., typing in a combo box). The server
	// uses the provided Action and Params to determine the context (e.g.,
	// "search workspace symbols for interfaces") and returns a filtered list
	// of matching entries.
	//
	// Note: This is a non-standard protocol extension.
	InteractiveListEnum(context.Context, *InteractiveListEnumParams) ([]FormEnumEntry, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocument_didChange
	DidChangeNotebookDocument(context.Context, *DidChangeNotebookDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocument_didClose
	DidCloseNotebookDocument(context.Context, *DidCloseNotebookDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocument_didOpen
	DidOpenNotebookDocument(context.Context, *DidOpenNotebookDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#notebookDocument_didSave
	DidSaveNotebookDocument(context.Context, *DidSaveNotebookDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#shutdown
	Shutdown(context.Context) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_codeAction
	CodeAction(context.Context, *CodeActionParams) ([]CodeAction, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_codeLens
	CodeLens(context.Context, *CodeLensParams) ([]CodeLens, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_colorPresentation
	ColorPresentation(context.Context, *ColorPresentationParams) ([]ColorPresentation, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_completion
	Completion(context.Context, *CompletionParams) (*CompletionList, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_declaration
	Declaration(context.Context, *DeclarationParams) (*Or_textDocument_declaration, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_definition
	Definition(context.Context, *DefinitionParams) ([]Location, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_diagnostic
	Diagnostic(context.Context, *DocumentDiagnosticParams) (*DocumentDiagnosticReport, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_didChange
	DidChange(context.Context, *DidChangeTextDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_didClose
	DidClose(context.Context, *DidCloseTextDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_didOpen
	DidOpen(context.Context, *DidOpenTextDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_didSave
	DidSave(context.Context, *DidSaveTextDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_documentColor
	DocumentColor(context.Context, *DocumentColorParams) ([]ColorInformation, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_documentHighlight
	DocumentHighlight(context.Context, *DocumentHighlightParams) ([]DocumentHighlight, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_documentLink
	DocumentLink(context.Context, *DocumentLinkParams) ([]DocumentLink, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_documentSymbol
	DocumentSymbol(context.Context, *DocumentSymbolParams) ([]any, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_foldingRange
	FoldingRange(context.Context, *FoldingRangeParams) ([]FoldingRange, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_formatting
	Formatting(context.Context, *DocumentFormattingParams) ([]TextEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_hover
	Hover(context.Context, *HoverParams) (*Hover, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_implementation
	Implementation(context.Context, *ImplementationParams) ([]Location, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_inlayHint
	InlayHint(context.Context, *InlayHintParams) ([]InlayHint, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_inlineCompletion
	InlineCompletion(context.Context, *InlineCompletionParams) (*Or_Result_textDocument_inlineCompletion, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_inlineValue
	InlineValue(context.Context, *InlineValueParams) ([]InlineValue, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_linkedEditingRange
	LinkedEditingRange(context.Context, *LinkedEditingRangeParams) (*LinkedEditingRanges, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_moniker
	Moniker(context.Context, *MonikerParams) ([]Moniker, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_onTypeFormatting
	OnTypeFormatting(context.Context, *DocumentOnTypeFormattingParams) ([]TextEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_prepareCallHierarchy
	PrepareCallHierarchy(context.Context, *CallHierarchyPrepareParams) ([]CallHierarchyItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_prepareRename
	PrepareRename(context.Context, *PrepareRenameParams) (*PrepareRenameResult, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_prepareTypeHierarchy
	PrepareTypeHierarchy(context.Context, *TypeHierarchyPrepareParams) ([]TypeHierarchyItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_rangeFormatting
	RangeFormatting(context.Context, *DocumentRangeFormattingParams) ([]TextEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_rangesFormatting
	RangesFormatting(context.Context, *DocumentRangesFormattingParams) ([]TextEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_references
	References(context.Context, *ReferenceParams) ([]Location, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_rename
	Rename(context.Context, *RenameParams) (*WorkspaceEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_selectionRange
	SelectionRange(context.Context, *SelectionRangeParams) ([]SelectionRange, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_semanticTokens_full
	SemanticTokensFull(context.Context, *SemanticTokensParams) (*SemanticTokens, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_semanticTokens_full_delta
	SemanticTokensFullDelta(context.Context, *SemanticTokensDeltaParams) (any, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_semanticTokens_range
	SemanticTokensRange(context.Context, *SemanticTokensRangeParams) (*SemanticTokens, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_signatureHelp
	SignatureHelp(context.Context, *SignatureHelpParams) (*SignatureHelp, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_typeDefinition
	TypeDefinition(context.Context, *TypeDefinitionParams) ([]Location, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_willSave
	WillSave(context.Context, *WillSaveTextDocumentParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#textDocument_willSaveWaitUntil
	WillSaveWaitUntil(context.Context, *WillSaveTextDocumentParams) ([]TextEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchy_subtypes
	Subtypes(context.Context, *TypeHierarchySubtypesParams) ([]TypeHierarchyItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#typeHierarchy_supertypes
	Supertypes(context.Context, *TypeHierarchySupertypesParams) ([]TypeHierarchyItem, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#window_workDoneProgress_cancel
	WorkDoneProgressCancel(context.Context, *WorkDoneProgressCancelParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_diagnostic
	DiagnosticWorkspace(context.Context, *WorkspaceDiagnosticParams) (*WorkspaceDiagnosticReport, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didChangeConfiguration
	DidChangeConfiguration(context.Context, *DidChangeConfigurationParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didChangeWatchedFiles
	DidChangeWatchedFiles(context.Context, *DidChangeWatchedFilesParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didChangeWorkspaceFolders
	DidChangeWorkspaceFolders(context.Context, *DidChangeWorkspaceFoldersParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didCreateFiles
	DidCreateFiles(context.Context, *CreateFilesParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didDeleteFiles
	DidDeleteFiles(context.Context, *DeleteFilesParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_didRenameFiles
	DidRenameFiles(context.Context, *RenameFilesParams) error
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_executeCommand
	ExecuteCommand(context.Context, *ExecuteCommandParams) (any, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_symbol
	Symbol(context.Context, *WorkspaceSymbolParams) ([]SymbolInformation, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_textDocumentContent
	TextDocumentContent(context.Context, *TextDocumentContentParams) (*TextDocumentContentResult, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_willCreateFiles
	WillCreateFiles(context.Context, *CreateFilesParams) (*WorkspaceEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_willDeleteFiles
	WillDeleteFiles(context.Context, *DeleteFilesParams) (*WorkspaceEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspace_willRenameFiles
	WillRenameFiles(context.Context, *RenameFilesParams) (*WorkspaceEdit, error)
	// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification#workspaceSymbol_resolve
	ResolveWorkspaceSymbol(context.Context, *WorkspaceSymbol) (*WorkspaceSymbol, error)
}

func serverDispatch(ctx context.Context, server Server, reply jsonrpc2.Replier, r jsonrpc2.Request) (bool, error) {
	resp, valid, err := ServerDispatchCall(ctx, server, r.Method(), r.Params())
	if !valid {
		return false, nil
	}

	if err != nil {
		return valid, reply(ctx, nil, err)
	} else {
		return valid, reply(ctx, resp, nil)
	}
}

func ServerDispatchCall(ctx context.Context, server Server, method string, raw json.RawMessage) (resp any, _ bool, err error) {
	switch method {
	case "$/progress":
		var params ProgressParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.Progress(ctx, &params)
		return nil, true, err

	case "$/setTrace":
		var params SetTraceParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.SetTrace(ctx, &params)
		return nil, true, err

	case "callHierarchy/incomingCalls":
		var params CallHierarchyIncomingCallsParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.IncomingCalls(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "callHierarchy/outgoingCalls":
		var params CallHierarchyOutgoingCallsParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.OutgoingCalls(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "codeAction/resolve":
		var params CodeAction
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveCodeAction(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "codeLens/resolve":
		var params CodeLens
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveCodeLens(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "command/resolve":
		var params ExecuteCommandParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveCommand(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "completionItem/resolve":
		var params CompletionItem
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveCompletionItem(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "documentLink/resolve":
		var params DocumentLink
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveDocumentLink(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "exit":
		err := server.Exit(ctx)
		return nil, true, err

	case "initialize":
		var params ParamInitialize
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Initialize(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "initialized":
		var params InitializedParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.Initialized(ctx, &params)
		return nil, true, err

	case "inlayHint/resolve":
		var params InlayHint
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Resolve(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "interactive/listEnum":
		var params InteractiveListEnumParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.InteractiveListEnum(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "notebookDocument/didChange":
		var params DidChangeNotebookDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidChangeNotebookDocument(ctx, &params)
		return nil, true, err

	case "notebookDocument/didClose":
		var params DidCloseNotebookDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidCloseNotebookDocument(ctx, &params)
		return nil, true, err

	case "notebookDocument/didOpen":
		var params DidOpenNotebookDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidOpenNotebookDocument(ctx, &params)
		return nil, true, err

	case "notebookDocument/didSave":
		var params DidSaveNotebookDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidSaveNotebookDocument(ctx, &params)
		return nil, true, err

	case "shutdown":
		err := server.Shutdown(ctx)
		return nil, true, err

	case "textDocument/codeAction":
		var params CodeActionParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.CodeAction(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/codeLens":
		var params CodeLensParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.CodeLens(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/colorPresentation":
		var params ColorPresentationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ColorPresentation(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/completion":
		var params CompletionParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Completion(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/declaration":
		var params DeclarationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Declaration(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/definition":
		var params DefinitionParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Definition(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/diagnostic":
		var params DocumentDiagnosticParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Diagnostic(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/didChange":
		var params DidChangeTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidChange(ctx, &params)
		return nil, true, err

	case "textDocument/didClose":
		var params DidCloseTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidClose(ctx, &params)
		return nil, true, err

	case "textDocument/didOpen":
		var params DidOpenTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidOpen(ctx, &params)
		return nil, true, err

	case "textDocument/didSave":
		var params DidSaveTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidSave(ctx, &params)
		return nil, true, err

	case "textDocument/documentColor":
		var params DocumentColorParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.DocumentColor(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/documentHighlight":
		var params DocumentHighlightParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.DocumentHighlight(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/documentLink":
		var params DocumentLinkParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.DocumentLink(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/documentSymbol":
		var params DocumentSymbolParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.DocumentSymbol(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/foldingRange":
		var params FoldingRangeParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.FoldingRange(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/formatting":
		var params DocumentFormattingParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Formatting(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/hover":
		var params HoverParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Hover(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/implementation":
		var params ImplementationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Implementation(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/inlayHint":
		var params InlayHintParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.InlayHint(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/inlineCompletion":
		var params InlineCompletionParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.InlineCompletion(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/inlineValue":
		var params InlineValueParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.InlineValue(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/linkedEditingRange":
		var params LinkedEditingRangeParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.LinkedEditingRange(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/moniker":
		var params MonikerParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Moniker(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/onTypeFormatting":
		var params DocumentOnTypeFormattingParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.OnTypeFormatting(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/prepareCallHierarchy":
		var params CallHierarchyPrepareParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.PrepareCallHierarchy(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/prepareRename":
		var params PrepareRenameParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.PrepareRename(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/prepareTypeHierarchy":
		var params TypeHierarchyPrepareParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.PrepareTypeHierarchy(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/rangeFormatting":
		var params DocumentRangeFormattingParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.RangeFormatting(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/rangesFormatting":
		var params DocumentRangesFormattingParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.RangesFormatting(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/references":
		var params ReferenceParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.References(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/rename":
		var params RenameParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.Rename(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/selectionRange":
		var params SelectionRangeParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.SelectionRange(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/semanticTokens/full":
		var params SemanticTokensParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.SemanticTokensFull(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/semanticTokens/full/delta":
		var params SemanticTokensDeltaParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.SemanticTokensFullDelta(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/semanticTokens/range":
		var params SemanticTokensRangeParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.SemanticTokensRange(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/signatureHelp":
		var params SignatureHelpParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.SignatureHelp(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/typeDefinition":
		var params TypeDefinitionParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		if params.Range == (Range{}) {
			params.Range = Range{
				Start: params.Position,
				End:   params.Position,
			}
		} else if !params.Range.Contains(params.Position) {
			return nil, true, fmt.Errorf("position %v is outside the provided range %v.", params.Position, params.Range)
		}
		resp, err := server.TypeDefinition(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "textDocument/willSave":
		var params WillSaveTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.WillSave(ctx, &params)
		return nil, true, err

	case "textDocument/willSaveWaitUntil":
		var params WillSaveTextDocumentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.WillSaveWaitUntil(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "typeHierarchy/subtypes":
		var params TypeHierarchySubtypesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Subtypes(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "typeHierarchy/supertypes":
		var params TypeHierarchySupertypesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Supertypes(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "window/workDoneProgress/cancel":
		var params WorkDoneProgressCancelParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.WorkDoneProgressCancel(ctx, &params)
		return nil, true, err

	case "workspace/diagnostic":
		var params WorkspaceDiagnosticParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.DiagnosticWorkspace(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/didChangeConfiguration":
		var params DidChangeConfigurationParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidChangeConfiguration(ctx, &params)
		return nil, true, err

	case "workspace/didChangeWatchedFiles":
		var params DidChangeWatchedFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidChangeWatchedFiles(ctx, &params)
		return nil, true, err

	case "workspace/didChangeWorkspaceFolders":
		var params DidChangeWorkspaceFoldersParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidChangeWorkspaceFolders(ctx, &params)
		return nil, true, err

	case "workspace/didCreateFiles":
		var params CreateFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidCreateFiles(ctx, &params)
		return nil, true, err

	case "workspace/didDeleteFiles":
		var params DeleteFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidDeleteFiles(ctx, &params)
		return nil, true, err

	case "workspace/didRenameFiles":
		var params RenameFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		err := server.DidRenameFiles(ctx, &params)
		return nil, true, err

	case "workspace/executeCommand":
		var params ExecuteCommandParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ExecuteCommand(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/symbol":
		var params WorkspaceSymbolParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.Symbol(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/textDocumentContent":
		var params TextDocumentContentParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.TextDocumentContent(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/willCreateFiles":
		var params CreateFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.WillCreateFiles(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/willDeleteFiles":
		var params DeleteFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.WillDeleteFiles(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspace/willRenameFiles":
		var params RenameFilesParams
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.WillRenameFiles(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	case "workspaceSymbol/resolve":
		var params WorkspaceSymbol
		if err := UnmarshalJSON(raw, &params); err != nil {
			return nil, true, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		resp, err := server.ResolveWorkspaceSymbol(ctx, &params)
		if err != nil {
			return nil, true, err
		}
		return resp, true, nil

	default:
		return nil, false, nil
	}
}

func (s *serverDispatcher) Progress(ctx context.Context, params *ProgressParams) error {
	return s.sender.Notify(ctx, "$/progress", params)
}
func (s *serverDispatcher) SetTrace(ctx context.Context, params *SetTraceParams) error {
	return s.sender.Notify(ctx, "$/setTrace", params)
}
func (s *serverDispatcher) IncomingCalls(ctx context.Context, params *CallHierarchyIncomingCallsParams) ([]CallHierarchyIncomingCall, error) {
	var result []CallHierarchyIncomingCall
	if err := s.sender.Call(ctx, "callHierarchy/incomingCalls", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) OutgoingCalls(ctx context.Context, params *CallHierarchyOutgoingCallsParams) ([]CallHierarchyOutgoingCall, error) {
	var result []CallHierarchyOutgoingCall
	if err := s.sender.Call(ctx, "callHierarchy/outgoingCalls", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveCodeAction(ctx context.Context, params *CodeAction) (*CodeAction, error) {
	var result *CodeAction
	if err := s.sender.Call(ctx, "codeAction/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveCodeLens(ctx context.Context, params *CodeLens) (*CodeLens, error) {
	var result *CodeLens
	if err := s.sender.Call(ctx, "codeLens/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveCommand(ctx context.Context, params *ExecuteCommandParams) (*ExecuteCommandParams, error) {
	var result *ExecuteCommandParams
	if err := s.sender.Call(ctx, "command/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveCompletionItem(ctx context.Context, params *CompletionItem) (*CompletionItem, error) {
	var result *CompletionItem
	if err := s.sender.Call(ctx, "completionItem/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveDocumentLink(ctx context.Context, params *DocumentLink) (*DocumentLink, error) {
	var result *DocumentLink
	if err := s.sender.Call(ctx, "documentLink/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Exit(ctx context.Context) error {
	return s.sender.Notify(ctx, "exit", nil)
}
func (s *serverDispatcher) Initialize(ctx context.Context, params *ParamInitialize) (*InitializeResult, error) {
	var result *InitializeResult
	if err := s.sender.Call(ctx, "initialize", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Initialized(ctx context.Context, params *InitializedParams) error {
	return s.sender.Notify(ctx, "initialized", params)
}
func (s *serverDispatcher) Resolve(ctx context.Context, params *InlayHint) (*InlayHint, error) {
	var result *InlayHint
	if err := s.sender.Call(ctx, "inlayHint/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) InteractiveListEnum(ctx context.Context, params *InteractiveListEnumParams) ([]FormEnumEntry, error) {
	var result []FormEnumEntry
	if err := s.sender.Call(ctx, "interactive/listEnum", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DidChangeNotebookDocument(ctx context.Context, params *DidChangeNotebookDocumentParams) error {
	return s.sender.Notify(ctx, "notebookDocument/didChange", params)
}
func (s *serverDispatcher) DidCloseNotebookDocument(ctx context.Context, params *DidCloseNotebookDocumentParams) error {
	return s.sender.Notify(ctx, "notebookDocument/didClose", params)
}
func (s *serverDispatcher) DidOpenNotebookDocument(ctx context.Context, params *DidOpenNotebookDocumentParams) error {
	return s.sender.Notify(ctx, "notebookDocument/didOpen", params)
}
func (s *serverDispatcher) DidSaveNotebookDocument(ctx context.Context, params *DidSaveNotebookDocumentParams) error {
	return s.sender.Notify(ctx, "notebookDocument/didSave", params)
}
func (s *serverDispatcher) Shutdown(ctx context.Context) error {
	return s.sender.Call(ctx, "shutdown", nil, nil)
}
func (s *serverDispatcher) CodeAction(ctx context.Context, params *CodeActionParams) ([]CodeAction, error) {
	var result []CodeAction
	if err := s.sender.Call(ctx, "textDocument/codeAction", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) CodeLens(ctx context.Context, params *CodeLensParams) ([]CodeLens, error) {
	var result []CodeLens
	if err := s.sender.Call(ctx, "textDocument/codeLens", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ColorPresentation(ctx context.Context, params *ColorPresentationParams) ([]ColorPresentation, error) {
	var result []ColorPresentation
	if err := s.sender.Call(ctx, "textDocument/colorPresentation", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Completion(ctx context.Context, params *CompletionParams) (*CompletionList, error) {
	var result *CompletionList
	if err := s.sender.Call(ctx, "textDocument/completion", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Declaration(ctx context.Context, params *DeclarationParams) (*Or_textDocument_declaration, error) {
	var result *Or_textDocument_declaration
	if err := s.sender.Call(ctx, "textDocument/declaration", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Definition(ctx context.Context, params *DefinitionParams) ([]Location, error) {
	var result []Location
	if err := s.sender.Call(ctx, "textDocument/definition", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Diagnostic(ctx context.Context, params *DocumentDiagnosticParams) (*DocumentDiagnosticReport, error) {
	var result *DocumentDiagnosticReport
	if err := s.sender.Call(ctx, "textDocument/diagnostic", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DidChange(ctx context.Context, params *DidChangeTextDocumentParams) error {
	return s.sender.Notify(ctx, "textDocument/didChange", params)
}
func (s *serverDispatcher) DidClose(ctx context.Context, params *DidCloseTextDocumentParams) error {
	return s.sender.Notify(ctx, "textDocument/didClose", params)
}
func (s *serverDispatcher) DidOpen(ctx context.Context, params *DidOpenTextDocumentParams) error {
	return s.sender.Notify(ctx, "textDocument/didOpen", params)
}
func (s *serverDispatcher) DidSave(ctx context.Context, params *DidSaveTextDocumentParams) error {
	return s.sender.Notify(ctx, "textDocument/didSave", params)
}
func (s *serverDispatcher) DocumentColor(ctx context.Context, params *DocumentColorParams) ([]ColorInformation, error) {
	var result []ColorInformation
	if err := s.sender.Call(ctx, "textDocument/documentColor", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DocumentHighlight(ctx context.Context, params *DocumentHighlightParams) ([]DocumentHighlight, error) {
	var result []DocumentHighlight
	if err := s.sender.Call(ctx, "textDocument/documentHighlight", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DocumentLink(ctx context.Context, params *DocumentLinkParams) ([]DocumentLink, error) {
	var result []DocumentLink
	if err := s.sender.Call(ctx, "textDocument/documentLink", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DocumentSymbol(ctx context.Context, params *DocumentSymbolParams) ([]any, error) {
	var result []any
	if err := s.sender.Call(ctx, "textDocument/documentSymbol", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) FoldingRange(ctx context.Context, params *FoldingRangeParams) ([]FoldingRange, error) {
	var result []FoldingRange
	if err := s.sender.Call(ctx, "textDocument/foldingRange", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Formatting(ctx context.Context, params *DocumentFormattingParams) ([]TextEdit, error) {
	var result []TextEdit
	if err := s.sender.Call(ctx, "textDocument/formatting", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Hover(ctx context.Context, params *HoverParams) (*Hover, error) {
	var result *Hover
	if err := s.sender.Call(ctx, "textDocument/hover", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Implementation(ctx context.Context, params *ImplementationParams) ([]Location, error) {
	var result []Location
	if err := s.sender.Call(ctx, "textDocument/implementation", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) InlayHint(ctx context.Context, params *InlayHintParams) ([]InlayHint, error) {
	var result []InlayHint
	if err := s.sender.Call(ctx, "textDocument/inlayHint", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) InlineCompletion(ctx context.Context, params *InlineCompletionParams) (*Or_Result_textDocument_inlineCompletion, error) {
	var result *Or_Result_textDocument_inlineCompletion
	if err := s.sender.Call(ctx, "textDocument/inlineCompletion", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) InlineValue(ctx context.Context, params *InlineValueParams) ([]InlineValue, error) {
	var result []InlineValue
	if err := s.sender.Call(ctx, "textDocument/inlineValue", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) LinkedEditingRange(ctx context.Context, params *LinkedEditingRangeParams) (*LinkedEditingRanges, error) {
	var result *LinkedEditingRanges
	if err := s.sender.Call(ctx, "textDocument/linkedEditingRange", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Moniker(ctx context.Context, params *MonikerParams) ([]Moniker, error) {
	var result []Moniker
	if err := s.sender.Call(ctx, "textDocument/moniker", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) OnTypeFormatting(ctx context.Context, params *DocumentOnTypeFormattingParams) ([]TextEdit, error) {
	var result []TextEdit
	if err := s.sender.Call(ctx, "textDocument/onTypeFormatting", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) PrepareCallHierarchy(ctx context.Context, params *CallHierarchyPrepareParams) ([]CallHierarchyItem, error) {
	var result []CallHierarchyItem
	if err := s.sender.Call(ctx, "textDocument/prepareCallHierarchy", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) PrepareRename(ctx context.Context, params *PrepareRenameParams) (*PrepareRenameResult, error) {
	var result *PrepareRenameResult
	if err := s.sender.Call(ctx, "textDocument/prepareRename", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) PrepareTypeHierarchy(ctx context.Context, params *TypeHierarchyPrepareParams) ([]TypeHierarchyItem, error) {
	var result []TypeHierarchyItem
	if err := s.sender.Call(ctx, "textDocument/prepareTypeHierarchy", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) RangeFormatting(ctx context.Context, params *DocumentRangeFormattingParams) ([]TextEdit, error) {
	var result []TextEdit
	if err := s.sender.Call(ctx, "textDocument/rangeFormatting", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) RangesFormatting(ctx context.Context, params *DocumentRangesFormattingParams) ([]TextEdit, error) {
	var result []TextEdit
	if err := s.sender.Call(ctx, "textDocument/rangesFormatting", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) References(ctx context.Context, params *ReferenceParams) ([]Location, error) {
	var result []Location
	if err := s.sender.Call(ctx, "textDocument/references", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Rename(ctx context.Context, params *RenameParams) (*WorkspaceEdit, error) {
	var result *WorkspaceEdit
	if err := s.sender.Call(ctx, "textDocument/rename", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) SelectionRange(ctx context.Context, params *SelectionRangeParams) ([]SelectionRange, error) {
	var result []SelectionRange
	if err := s.sender.Call(ctx, "textDocument/selectionRange", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) SemanticTokensFull(ctx context.Context, params *SemanticTokensParams) (*SemanticTokens, error) {
	var result *SemanticTokens
	if err := s.sender.Call(ctx, "textDocument/semanticTokens/full", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) SemanticTokensFullDelta(ctx context.Context, params *SemanticTokensDeltaParams) (any, error) {
	var result any
	if err := s.sender.Call(ctx, "textDocument/semanticTokens/full/delta", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) SemanticTokensRange(ctx context.Context, params *SemanticTokensRangeParams) (*SemanticTokens, error) {
	var result *SemanticTokens
	if err := s.sender.Call(ctx, "textDocument/semanticTokens/range", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) SignatureHelp(ctx context.Context, params *SignatureHelpParams) (*SignatureHelp, error) {
	var result *SignatureHelp
	if err := s.sender.Call(ctx, "textDocument/signatureHelp", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) TypeDefinition(ctx context.Context, params *TypeDefinitionParams) ([]Location, error) {
	var result []Location
	if err := s.sender.Call(ctx, "textDocument/typeDefinition", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) WillSave(ctx context.Context, params *WillSaveTextDocumentParams) error {
	return s.sender.Notify(ctx, "textDocument/willSave", params)
}
func (s *serverDispatcher) WillSaveWaitUntil(ctx context.Context, params *WillSaveTextDocumentParams) ([]TextEdit, error) {
	var result []TextEdit
	if err := s.sender.Call(ctx, "textDocument/willSaveWaitUntil", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Subtypes(ctx context.Context, params *TypeHierarchySubtypesParams) ([]TypeHierarchyItem, error) {
	var result []TypeHierarchyItem
	if err := s.sender.Call(ctx, "typeHierarchy/subtypes", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Supertypes(ctx context.Context, params *TypeHierarchySupertypesParams) ([]TypeHierarchyItem, error) {
	var result []TypeHierarchyItem
	if err := s.sender.Call(ctx, "typeHierarchy/supertypes", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) WorkDoneProgressCancel(ctx context.Context, params *WorkDoneProgressCancelParams) error {
	return s.sender.Notify(ctx, "window/workDoneProgress/cancel", params)
}
func (s *serverDispatcher) DiagnosticWorkspace(ctx context.Context, params *WorkspaceDiagnosticParams) (*WorkspaceDiagnosticReport, error) {
	var result *WorkspaceDiagnosticReport
	if err := s.sender.Call(ctx, "workspace/diagnostic", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) DidChangeConfiguration(ctx context.Context, params *DidChangeConfigurationParams) error {
	return s.sender.Notify(ctx, "workspace/didChangeConfiguration", params)
}
func (s *serverDispatcher) DidChangeWatchedFiles(ctx context.Context, params *DidChangeWatchedFilesParams) error {
	return s.sender.Notify(ctx, "workspace/didChangeWatchedFiles", params)
}
func (s *serverDispatcher) DidChangeWorkspaceFolders(ctx context.Context, params *DidChangeWorkspaceFoldersParams) error {
	return s.sender.Notify(ctx, "workspace/didChangeWorkspaceFolders", params)
}
func (s *serverDispatcher) DidCreateFiles(ctx context.Context, params *CreateFilesParams) error {
	return s.sender.Notify(ctx, "workspace/didCreateFiles", params)
}
func (s *serverDispatcher) DidDeleteFiles(ctx context.Context, params *DeleteFilesParams) error {
	return s.sender.Notify(ctx, "workspace/didDeleteFiles", params)
}
func (s *serverDispatcher) DidRenameFiles(ctx context.Context, params *RenameFilesParams) error {
	return s.sender.Notify(ctx, "workspace/didRenameFiles", params)
}
func (s *serverDispatcher) ExecuteCommand(ctx context.Context, params *ExecuteCommandParams) (any, error) {
	var result any
	if err := s.sender.Call(ctx, "workspace/executeCommand", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) Symbol(ctx context.Context, params *WorkspaceSymbolParams) ([]SymbolInformation, error) {
	var result []SymbolInformation
	if err := s.sender.Call(ctx, "workspace/symbol", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) TextDocumentContent(ctx context.Context, params *TextDocumentContentParams) (*TextDocumentContentResult, error) {
	var result *TextDocumentContentResult
	if err := s.sender.Call(ctx, "workspace/textDocumentContent", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) WillCreateFiles(ctx context.Context, params *CreateFilesParams) (*WorkspaceEdit, error) {
	var result *WorkspaceEdit
	if err := s.sender.Call(ctx, "workspace/willCreateFiles", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) WillDeleteFiles(ctx context.Context, params *DeleteFilesParams) (*WorkspaceEdit, error) {
	var result *WorkspaceEdit
	if err := s.sender.Call(ctx, "workspace/willDeleteFiles", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) WillRenameFiles(ctx context.Context, params *RenameFilesParams) (*WorkspaceEdit, error) {
	var result *WorkspaceEdit
	if err := s.sender.Call(ctx, "workspace/willRenameFiles", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}
func (s *serverDispatcher) ResolveWorkspaceSymbol(ctx context.Context, params *WorkspaceSymbol) (*WorkspaceSymbol, error) {
	var result *WorkspaceSymbol
	if err := s.sender.Call(ctx, "workspaceSymbol/resolve", params, &result); err != nil {
		return nil, err
	}
	return result, nil
}


================================================
FILE: gopls/internal/protocol/uri.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package protocol

// This file declares URI, DocumentURI, and its methods.
//
// For the LSP definition of these types, see
// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#uri

import (
	"fmt"
	"net/url"
	"path/filepath"
	"strings"
	"unicode"

	"golang.org/x/tools/gopls/internal/util/pathutil"
)

// A DocumentURI is the URI of a client editor document.
//
// According to the LSP specification:
//
//	Care should be taken to handle encoding in URIs. For
//	example, some clients (such as VS Code) may encode colons
//	in drive letters while others do not. The URIs below are
//	both valid, but clients and servers should be consistent
//	with the form they use themselves to ensure the other party
//	doesn’t interpret them as distinct URIs. Clients and
//	servers should not assume that each other are encoding the
//	same way (for example a client encoding colons in drive
//	letters cannot assume server responses will have encoded
//	colons). The same applies to casing of drive letters - one
//	party should not assume the other party will return paths
//	with drive letters cased the same as it.
//
//	file:///c:/project/readme.md
//	file:///C%3A/project/readme.md
//
// This is done during JSON unmarshalling;
// see [DocumentURI.UnmarshalText] for details.
type DocumentURI string

// A URI is an arbitrary URL (e.g. https), not necessarily a file.
type URI = string

// UnmarshalText implements decoding of DocumentURI values.
//
// In particular, it implements a systematic correction of various odd
// features of the definition of DocumentURI in the LSP spec that
// appear to be workarounds for bugs in VS Code. For example, it may
// URI-encode the URI itself, so that colon becomes %3A, and it may
// send file://foo.go URIs that have two slashes (not three) and no
// hostname.
//
// We use UnmarshalText, not UnmarshalJSON, because it is called even
// for non-addressable values such as keys and values of map[K]V,
// where there is no pointer of type *K or *V on which to call
// UnmarshalJSON. (See Go issue #28189 for more detail.)
//
// Non-empty DocumentURIs are valid "file"-scheme URIs.
// The empty DocumentURI is valid.
func (uri *DocumentURI) UnmarshalText(data []byte) (err error) {
	*uri, err = ParseDocumentURI(string(data))
	return
}

// Clean returns the cleaned uri by triggering filepath.Clean underlying.
func (uri DocumentURI) Clean() DocumentURI {
	return URIFromPath(filepath.Clean(uri.Path()))
}

// Path returns the file path for the given URI.
//
// DocumentURI("").Path() returns the empty string.
//
// Path panics if called on a URI that is not a valid filename.
func (uri DocumentURI) Path() string {
	filename, err := filename(uri)
	if err != nil {
		// e.g. ParseRequestURI failed.
		//
		// This can only affect DocumentURIs created by
		// direct string manipulation; all DocumentURIs
		// received from the client pass through
		// ParseRequestURI, which ensures validity.
		panic(err)
	}
	return filepath.FromSlash(filename)
}

// Base returns the base name of the file path of the given URI.
func (uri DocumentURI) Base() string {
	return filepath.Base(uri.Path())
}

// Dir returns the URI for the directory containing the receiver.
func (uri DocumentURI) Dir() DocumentURI {
	// This function could be more efficiently implemented by avoiding any call
	// to Path(), but at least consolidates URI manipulation.
	return URIFromPath(uri.DirPath())
}

// DirPath returns the file path to the directory containing this URI, which
// must be a file URI.
func (uri DocumentURI) DirPath() string {
	return filepath.Dir(uri.Path())
}

// Encloses reports whether uri's path, considered as a sequence of segments,
// is a prefix of file's path.
func (uri DocumentURI) Encloses(file DocumentURI) bool {
	return pathutil.InDir(uri.Path(), file.Path())
}

// Location returns the Location for the specified range of this URI's file.
func (uri DocumentURI) Location(rng Range) Location {
	return Location{URI: uri, Range: rng}
}

func filename(uri DocumentURI) (string, error) {
	if uri == "" {
		return "", nil
	}

	// This conservative check for the common case
	// of a simple non-empty absolute POSIX filename
	// avoids the allocation of a net.URL.
	if strings.HasPrefix(string(uri), "file:///") {
		rest := string(uri)[len("file://"):] // leave one slash
		for i := 0; i < len(rest); i++ {
			b := rest[i]
			// Reject these cases:
			if b < ' ' || b == 0x7f || // control character
				b == '%' || b == '+' || // URI escape
				b == ':' || // Windows drive letter
				b == '&' || b == '?' { // authority or query
				goto slow
			}
			// We do not reject '@' as it cannot be part of the
			// authority (e.g. user:pass@example.com) in a
			// "file:///" URL, and '@' commonly appears in file
			// paths such as GOMODCACHE/module@version/...
		}
		return rest, nil
	}
slow:

	u, err := url.ParseRequestURI(string(uri))
	if err != nil {
		return "", err
	}
	if u.Scheme != fileScheme {
		return "", fmt.Errorf("only file URIs are supported, got %q from %q", u.Scheme, uri)
	}
	// If the URI is a Windows URI, we trim the leading "/" and uppercase
	// the drive letter, which will never be case sensitive.
	if isWindowsDriveURIPath(u.Path) {
		u.Path = strings.ToUpper(string(u.Path[1])) + u.Path[2:]
	}

	return u.Path, nil
}

// ParseDocumentURI interprets a string as a DocumentURI, applying VS
// Code workarounds; see [DocumentURI.UnmarshalText] for details.
// If "s" is a file name, use [URIFromPath] instead.
func ParseDocumentURI(s string) (DocumentURI, error) {
	if s == "" {
		return "", nil
	}

	if !strings.HasPrefix(s, "file://") {
		return "", fmt.Errorf("DocumentURI scheme is not 'file': %s", s)
	}

	// VS Code sends URLs with only two slashes,
	// which are invalid. golang/go#39789.
	if !strings.HasPrefix(s, "file:///") {
		s = "file:///" + s[len("file://"):]
	}

	// Even though the input is a URI, it may not be in canonical form. VS Code
	// in particular over-escapes :, @, etc. Unescape and re-encode to canonicalize.
	path, err := url.PathUnescape(s[len("file://"):])
	if err != nil {
		return "", err
	}

	// File URIs from Windows may have lowercase drive letters.
	// Since drive letters are guaranteed to be case insensitive,
	// we change them to uppercase to remain consistent.
	// For example, file:///c:/x/y/z becomes file:///C:/x/y/z.
	if isWindowsDriveURIPath(path) {
		path = path[:1] + strings.ToUpper(string(path[1])) + path[2:]
	}
	u := url.URL{Scheme: fileScheme, Path: path}
	return DocumentURI(u.String()), nil
}

// URIFromPath returns DocumentURI for the supplied file path.
// Given "", it returns "".
func URIFromPath(path string) DocumentURI {
	if path == "" {
		return ""
	}
	if !IsWindowsDrivePath(path) {
		if abs, err := filepath.Abs(path); err == nil {
			path = abs
		}
	}
	// Check the file path again, in case it became absolute.
	if IsWindowsDrivePath(path) {
		path = "/" + strings.ToUpper(string(path[0])) + path[1:]
	}
	path = filepath.ToSlash(path)
	u := url.URL{
		Scheme: fileScheme,
		Path:   path,
	}
	return DocumentURI(u.String())
}

const fileScheme = "file"

// IsWindowsDrivePath returns true if the file path is of the form used by
// Windows. We check if the path begins with a drive letter, followed by a ":".
// For example: C:/x/y/z.
func IsWindowsDrivePath(path string) bool {
	if len(path) < 3 {
		return false
	}
	return unicode.IsLetter(rune(path[0])) && path[1] == ':'
}

// isWindowsDriveURIPath returns true if the file URI is of the format used by
// Windows URIs. The url.Parse package does not specially handle Windows paths
// (see golang/go#6027), so we check if the URI path has a drive prefix (e.g. "/C:").
func isWindowsDriveURIPath(uri string) bool {
	if len(uri) < 4 {
		return false
	}
	return uri[0] == '/' && unicode.IsLetter(rune(uri[1])) && uri[2] == ':'
}


================================================
FILE: gopls/internal/protocol/uri_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !windows

package protocol_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

// TestURIFromPath tests the conversion between URIs and filenames. The test cases
// include Windows-style URIs and filepaths, but we avoid having OS-specific
// tests by using only forward slashes, assuming that the standard library
// functions filepath.ToSlash and filepath.FromSlash do not need testing.
func TestURIFromPath(t *testing.T) {
	for _, test := range []struct {
		path, wantFile string
		wantURI        protocol.DocumentURI
	}{
		{
			path:     ``,
			wantFile: ``,
			wantURI:  protocol.DocumentURI(""),
		},
		{
			path:     `C:/Windows/System32`,
			wantFile: `C:/Windows/System32`,
			wantURI:  protocol.DocumentURI("file:///C:/Windows/System32"),
		},
		{
			path:     `C:/Go/src/bob.go`,
			wantFile: `C:/Go/src/bob.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob.go"),
		},
		{
			path:     `c:/Go/src/bob.go`,
			wantFile: `C:/Go/src/bob.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob.go"),
		},
		{
			path:     `/path/to/dir`,
			wantFile: `/path/to/dir`,
			wantURI:  protocol.DocumentURI("file:///path/to/dir"),
		},
		{
			path:     `/a/b/c/src/bob.go`,
			wantFile: `/a/b/c/src/bob.go`,
			wantURI:  protocol.DocumentURI("file:///a/b/c/src/bob.go"),
		},
		{
			path:     `c:/Go/src/bob george/george/george.go`,
			wantFile: `C:/Go/src/bob george/george/george.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob%20george/george/george.go"),
		},
	} {
		got := protocol.URIFromPath(test.path)
		if got != test.wantURI {
			t.Errorf("URIFromPath(%q): got %q, expected %q", test.path, got, test.wantURI)
		}
		gotFilename := got.Path()
		if gotFilename != test.wantFile {
			t.Errorf("Filename(%q): got %q, expected %q", got, gotFilename, test.wantFile)
		}
	}
}

func TestParseDocumentURI(t *testing.T) {
	for _, test := range []struct {
		input    string
		want     string // string(DocumentURI) on success or error.Error() on failure
		wantPath string // expected DocumentURI.Path on success
	}{
		{
			input:    `file:///c:/Go/src/bob%20george/george/george.go`,
			want:     "file:///C:/Go/src/bob%20george/george/george.go",
			wantPath: `C:/Go/src/bob george/george/george.go`,
		},
		{
			input:    `file:///C%3A/Go/src/bob%20george/george/george.go`,
			want:     "file:///C:/Go/src/bob%20george/george/george.go",
			wantPath: `C:/Go/src/bob george/george/george.go`,
		},
		{
			input:    `file:///path/to/%25p%25ercent%25/per%25cent.go`,
			want:     `file:///path/to/%25p%25ercent%25/per%25cent.go`,
			wantPath: `/path/to/%p%ercent%/per%cent.go`,
		},
		{
			input:    `file:///C%3A/`,
			want:     `file:///C:/`,
			wantPath: `C:/`,
		},
		{
			input:    `file:///`,
			want:     `file:///`,
			wantPath: `/`,
		},
		{
			input:    `file://wsl%24/Ubuntu/home/wdcui/repo/VMEnclaves/cvm-runtime`,
			want:     `file:///wsl$/Ubuntu/home/wdcui/repo/VMEnclaves/cvm-runtime`,
			wantPath: `/wsl$/Ubuntu/home/wdcui/repo/VMEnclaves/cvm-runtime`,
		},
		{
			input:    "",
			want:     "",
			wantPath: "",
		},
		// Errors:
		{
			input: "https://go.dev/",
			want:  "DocumentURI scheme is not 'file': https://go.dev/",
		},
	} {
		uri, err := protocol.ParseDocumentURI(test.input)
		var got string
		if err != nil {
			got = err.Error()
		} else {
			got = string(uri)
		}
		if got != test.want {
			t.Errorf("ParseDocumentURI(%q): got %q, want %q", test.input, got, test.want)
		}
		if err == nil && uri.Path() != test.wantPath {
			t.Errorf("DocumentURI(%s).Path = %q, want %q", uri,
				uri.Path(), test.wantPath)
		}
	}
}


================================================
FILE: gopls/internal/protocol/uri_windows_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build windows

package protocol_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

// TestURIFromPath tests the conversion between URIs and filenames. The test cases
// include Windows-style URIs and filepaths, but we avoid having OS-specific
// tests by using only forward slashes, assuming that the standard library
// functions filepath.ToSlash and filepath.FromSlash do not need testing.
func TestURIFromPath(t *testing.T) {
	rootPath, err := filepath.Abs("/")
	if err != nil {
		t.Fatal(err)
	}
	if len(rootPath) < 2 || rootPath[1] != ':' {
		t.Fatalf("malformed root path %q", rootPath)
	}
	driveLetter := string(rootPath[0])

	for _, test := range []struct {
		path, wantFile string
		wantURI        protocol.DocumentURI
	}{
		{
			path:     ``,
			wantFile: ``,
			wantURI:  protocol.DocumentURI(""),
		},
		{
			path:     `C:\Windows\System32`,
			wantFile: `C:\Windows\System32`,
			wantURI:  protocol.DocumentURI("file:///C:/Windows/System32"),
		},
		{
			path:     `C:\Go\src\bob.go`,
			wantFile: `C:\Go\src\bob.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob.go"),
		},
		{
			path:     `c:\Go\src\bob.go`,
			wantFile: `C:\Go\src\bob.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob.go"),
		},
		{
			path:     `\path\to\dir`,
			wantFile: driveLetter + `:\path\to\dir`,
			wantURI:  protocol.DocumentURI("file:///" + driveLetter + ":/path/to/dir"),
		},
		{
			path:     `\a\b\c\src\bob.go`,
			wantFile: driveLetter + `:\a\b\c\src\bob.go`,
			wantURI:  protocol.DocumentURI("file:///" + driveLetter + ":/a/b/c/src/bob.go"),
		},
		{
			path:     `c:\Go\src\bob george\george\george.go`,
			wantFile: `C:\Go\src\bob george\george\george.go`,
			wantURI:  protocol.DocumentURI("file:///C:/Go/src/bob%20george/george/george.go"),
		},
	} {
		got := protocol.URIFromPath(test.path)
		if got != test.wantURI {
			t.Errorf("URIFromPath(%q): got %q, expected %q", test.path, got, test.wantURI)
		}
		gotFilename := got.Path()
		if gotFilename != test.wantFile {
			t.Errorf("Filename(%q): got %q, expected %q", got, gotFilename, test.wantFile)
		}
	}
}

func TestParseDocumentURI(t *testing.T) {
	for _, test := range []struct {
		input    string
		want     string // string(DocumentURI) on success or error.Error() on failure
		wantPath string // expected DocumentURI.Path on success
	}{
		{
			input:    `file:///c:/Go/src/bob%20george/george/george.go`,
			want:     "file:///C:/Go/src/bob%20george/george/george.go",
			wantPath: `C:\Go\src\bob george\george\george.go`,
		},
		{
			input:    `file:///C%3A/Go/src/bob%20george/george/george.go`,
			want:     "file:///C:/Go/src/bob%20george/george/george.go",
			wantPath: `C:\Go\src\bob george\george\george.go`,
		},
		{
			input:    `file:///c:/path/to/%25p%25ercent%25/per%25cent.go`,
			want:     `file:///C:/path/to/%25p%25ercent%25/per%25cent.go`,
			wantPath: `C:\path\to\%p%ercent%\per%cent.go`,
		},
		{
			input:    `file:///C%3A/`,
			want:     `file:///C:/`,
			wantPath: `C:\`,
		},
		{
			input:    `file:///`,
			want:     `file:///`,
			wantPath: `\`,
		},
		{
			input:    "",
			want:     "",
			wantPath: "",
		},
		// Errors:
		{
			input: "https://go.dev/",
			want:  "DocumentURI scheme is not 'file': https://go.dev/",
		},
	} {
		uri, err := protocol.ParseDocumentURI(test.input)
		var got string
		if err != nil {
			got = err.Error()
		} else {
			got = string(uri)
		}
		if got != test.want {
			t.Errorf("ParseDocumentURI(%q): got %q, want %q", test.input, got, test.want)
		}
		if err == nil && uri.Path() != test.wantPath {
			t.Errorf("DocumentURI(%s).Path = %q, want %q", uri,
				uri.Path(), test.wantPath)
		}
	}
}


================================================
FILE: gopls/internal/server/assets/common.css
================================================
/* Copyright 2024 The Go Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 */

/* inspired by pkg.go.dev's typography.css */

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Helvetica, Arial, sans-serif, 'Apple Color Emoji', 'Segoe UI Emoji';
  font-size: 1rem;
  line-height: normal;
}

h1 {
  font-size: 1.5rem;
}

h2 {
  font-size: 1.375rem;
}

h3 {
  font-size: 1.25rem;
}

h4 {
  font-size: 1.125rem;
}

h5 {
  font-size: 1rem;
}

h6 {
  font-size: 0.875rem;
}

h1,
h2,
h3,
h4 {
  font-weight: 600;
  line-height: 1.25em;
  word-break: break-word;
}

h5,
h6 {
  font-weight: 500;
  line-height: 1.3em;
  word-break: break-word;
}

p {
  font-size: 1rem;
  line-height: 1.5rem;
  max-width: 60rem;
}

strong {
  font-weight: 600;
}

code,
pre,
textarea.code {
  font-family: Consolas, 'Liberation Mono', Menlo, monospace;
  font-size: 0.875rem;
  line-height: 1.5em;
}

pre,
textarea.code {
  background-color: #eee;
  border: 3px;
  border-radius: 3px;
  color: black;
  overflow-x: auto;
  padding: 0.625rem;
  tab-size: 4;
  white-space: pre;
}

button,
input,
select,
textarea {
  font: inherit;
}

a,
a:link,
a:visited {
  color: rgb(0, 125, 156);
  text-decoration: none;
}

a:hover,
a:focus {
  color: rgb(0, 125, 156);
  text-decoration: underline;
}

a:hover > * {
  text-decoration: underline;
}

#disconnected {
  position: fixed;
  top: 1em;
  left: 1em;
  display: none; /* initially */
  background-color: white;
  border: thick solid red;
  padding: 2em;
}


================================================
FILE: gopls/internal/server/assets/common.js
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// httpGET requests a URL for its effects only.
// (It is needed for /open URLs; see objHTML.)
function httpGET(url) {
	var x = new XMLHttpRequest();
	x.open("GET", url, true);
	x.send();
	return false; // disable usual <a href=...> behavior
}

// disconnect banner
window.addEventListener('load', function() {
	// Create a hidden <div id='disconnected'> element.
	var banner = document.createElement("div");
	banner.id = "disconnected";
	banner.innerText = "Gopls server has terminated. Page is inactive.";
	document.body.appendChild(banner);

	// Start a GET /hang request. If it ever completes, the server
	// has disconnected. Reveal the banner in that case.
	var x = new XMLHttpRequest();
	x.open("GET", "/hang", true);
	x.onloadend = () => { banner.style.display = "block"; };
	x.send();
});


================================================
FILE: gopls/internal/server/assets/splitpkg.css
================================================
/* Copyright 2025 The Go Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style
 * license that can be found in the LICENSE file.
 */

li {
			list-style: none;
}
span.component {
    display:		inline-block;
    min-width:		8em;
}
span.delete {
    color:		grey;
    opacity:		0.3;
}
span.delete:hover {
			opacity: 1;
}
hr {
    border-top:		thin solid #EEE;
}
p.help {
    width:		6in;
    line-height:	120%; /* tighter than default */
    font-size:		80%;
    text-align:		justify;
    text-justify:	inter-word;
    color:		#AAA;
}


================================================
FILE: gopls/internal/server/assets/splitpkg.js
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// data holds the application state, of Go type splitpkg.ResultJSON.
// Each reload() replaces it by the current server state.
var data = null;

// One-time setup.
window.addEventListener('load', function() {
  document.getElementById('add-component').addEventListener('click', onClickAddComponent);
  document.getElementById('assign-apply').addEventListener('click', onClickApplyAssignment);

  reload();
});

/**
 * onClickAddComponent adds a new component, posts it to the server,
 * and reloads the page.
 */
function onClickAddComponent(event) {
  const name = document.getElementById('new-component').value.trim();
  if (name == "") {
    alert("empty component name");
    return;
  }
  if (data.Components.Names.includes(name)) {
    alert("duplicate component name");
    return;
  }
  data.Components.Names.push(name);
  postComponents();
  reload();
}

/**
 * onClickDeleteComponent deletes a component, posts it to the server,
 * and reloads the page.
 */
function onClickDeleteComponent(event) {
  const li = event.target.parentNode;
  li.parentNode.removeChild(li);

  const index = li.index; // of deleted component

  const names = data.Components.Names;
  names.splice(index, 1);

  // Update assignments after implicit renumbering of components.
  const assignments = data.Components.Assignments;
  Object.entries(assignments).forEach(([k, compIndex]) => {
    if (compIndex == index) {
      assignments[k] = 0; // => default component
    } else if (compIndex > index) {
      assignments[k] = compIndex - 1;
    }
  });

  postComponents();
  reload();
}

/** postComponents notifies the server of a change in the Components information. */
function postComponents() {
  // Post the updated components.
  const xhr = new XMLHttpRequest();
  xhr.open("POST", makeURL('/splitpkg-components'), false); // false => synchronous
  xhr.setRequestHeader('Content-Type', 'application/json');
  xhr.send(JSON.stringify(data.Components));
  if (xhr.status === 200) {
    // ok
  } else {
    alert("failed to post new component list: " + xhr.statusText);
    return;
  }
}

/**
 * onClickApplyAssignment is called when the Apply button is clicked.
 * It updates the component assignment mapping.
 */
function onClickApplyAssignment(event) {
  const componentIndex = document.getElementById('assign-select').selectedIndex;

  // Update the component assignment of each spec
  // whose <li class='spec-node'> checkbox is checked.
  document.querySelectorAll('li.spec-node').forEach((specItem) => {
    const checkbox = specItem.firstChild;
    if (checkbox.checked) {
      data.Components.Assignments[specItem.dataset.name] = componentIndex;
    }
  });

  postComponents(); // update the server
  reload(); // recompute the page state
}

/**
 * reload requests the current server state,
 * updates the global 'data' variable,
 * and rebuilds the page DOM to reflect the state.
 */
function reload() {
  const xhr = new XMLHttpRequest();
  xhr.open("GET", makeURL('/splitpkg-json'), false); // false => synchronous
  xhr.send(null);
  if (xhr.status === 200) {
    try {
      data = JSON.parse(xhr.responseText);
    } catch (e) {
      alert("error parsing JSON: " + e);
      return null;
    }
  } else {
    alert("request failed: " + xhr.statusText);
    return null;
  }

  // Ensure there is always a default component.
  if (!data.Components.Names) { // undefined, null, or empty
    data.Components.Names = ["default"];
  }
  if (!data.Components.Assignments) { // undefined, null, or empty
    data.Components.Assignments = {};
  }

  // Rebuild list of components.
  const componentsContainer = document.getElementById('components');
  componentsContainer.replaceChildren(); // clear out previous state
  const assignSelect = document.getElementById('assign-select');
  assignSelect.replaceChildren(); // clear out previous state
  const componentsList = document.createElement('ul');
  componentsContainer.appendChild(componentsList);
  data.Components.Names.forEach((name, i) => {
      // <li>■ name ×
    const li = document.createElement('li');
    li.index = i; // custom index field holds component index (for onClickDeleteComponent)
    componentsList.appendChild(li);

    // ■ name
    const span = document.createElement('span');
    span.className = 'component';
    span.style.color = componentColors[i % componentColors.length];
    span.append('■ ', name)
    li.append(span);

    // ×
    if (i > 0) { // the default component cannot be deleted
      const xSpan = document.createElement('span');
      xSpan.className = 'delete';
      xSpan.append(' ×')
      xSpan.addEventListener('click', onClickDeleteComponent);
      li.append(xSpan);
    }

    // Add component to the assignment dropdown.
    assignSelect.add(new Option(name, null));
  })

  // Rebuild list of decls grouped by file.
  const filesContainer = document.getElementById('files');
  filesContainer.replaceChildren(); // clear out previous state
  data.Files.forEach(fileJson => {
    filesContainer.appendChild(createFileDiv(fileJson));
  });

  // Display strongly connected components.
  const deps = document.getElementById('deps');
  deps.replaceChildren(); // clear out previous state
  const depsList = document.createElement('ul');
  deps.append(depsList);

  // Be explicit if there are no component dependencies.
  if (data.Edges.length == 0) {
    const li = document.createElement('li');
    depsList.append(li);
    li.append("No dependencies");
    return;
  }

  // List all sets of mutually dependent components.
  data.Cycles.forEach((scc) => {
    const item = document.createElement('li');
    item.append("⚠ Component cycle: " +
		scc.map(index => data.Components.Names[index]).join(', '))
    depsList.append(item);
  })

  // Show intercomponent edges.
  data.Edges.forEach((edge) => {
    const edgeItem = document.createElement('li');
    depsList.append(edgeItem);

    // component edge
    const from = data.Components.Names[edge.From];
    const to   = data.Components.Names[edge.To];
    edgeItem.append((edge.Cyclic ? "⚠ " : "") + from + " ➤ " + to);

    // sublist of symbol references that induced the edge
    const refsList = document.createElement('ul');
    edgeItem.appendChild(refsList);
    refsList.className = 'refs-list';
    edge.Refs.forEach(ref => {
      refsList.appendChild(createRefItem(ref));
    });
  })
}

/**
 * makeURL returns a URL string with the specified path,
 * but preserving the current page's query parameters (view, pkg).
 */
function makeURL(path) {
  const url = new URL(window.location.href);
  url.pathname = url.pathname.substring(0, url.pathname.lastIndexOf('/')) + path;
  return url.href;
}

/** createFileDiv creates a <div> for a fileJSON object. */
function createFileDiv(fileData) {
  // Create the main container for the file entry.
  const fileContainer = document.createElement('div');
  fileContainer.className = 'file-node';

  // Create and append the file's base name as a para.
  const para = document.createElement('p');
  fileContainer.appendChild(para);

  // The file's checkbox applies in bulk to all specs within it.
  var specCheckboxes = [];
  const fileCheckbox = document.createElement('input');
  fileCheckbox.type = 'checkbox';
  fileCheckbox.addEventListener('click', (event) => {
    // Select/deselect all specs belonging to the file.
    const checked = event.target.checked;
    specCheckboxes.forEach(checkbox => {
      checkbox.checked = checked;
    });
  })
  para.appendChild(fileCheckbox);
  para.append("File ");

  // Link file name to start of file.
  const baseName = document.createElement('a');
  para.appendChild(baseName);
  baseName.className = 'file-link';
  baseName.textContent = fileData.Base;
  baseName.addEventListener('click', () => httpGET(fileData.URL));

  // Process declarations if they exist.
  if (fileData.Decls && fileData.Decls.length > 0) {
    const declsList = document.createElement('ul');
    declsList.className = 'decls-list';
    // For now we flatten out the decl/spec grouping.
    fileData.Decls.forEach(decl => {
      if (decl.Specs && decl.Specs.length > 0) {
        decl.Specs.forEach(spec => {
          declsList.appendChild(createSpecItem(decl.Kind, spec, specCheckboxes));
        });
      }
    });
    fileContainer.appendChild(declsList);
  }

  return fileContainer;
}

/** createSpecItem creates an <li> element for a specJSON object (one declared name). */
function createSpecItem(kind, specData, checkboxes) {
  // <li><checkbox/>ⓕ <a>myfunc</a>...
  const specItem = document.createElement('li');
  specItem.className = 'spec-node';
  specItem.dataset.name = specData.Name; // custom .name field holds symbol's unique logical name

  // First child is a checkbox.
  const specCheckbox = document.createElement('input');
  specCheckbox.type = 'checkbox';
  specItem.appendChild(specCheckbox);
  checkboxes.push(specCheckbox);

  // Next is the component assignment color swatch.
  const assignSpan = document.createElement('span');
  assignSpan.className = 'component-swatch';
  assignSpan.textContent = "■";
  {
    var index = data.Components.Assignments[specData.Name]; // may be undefined
    if (!index) {
      index = 0; // default
    }
    assignSpan.style.color = componentColors[index % componentColors.length];
    assignSpan.title = "Component " + data.Components.Names[index]; // tooltip
  }
  specItem.appendChild(assignSpan);

  // Encircle the func/var/const/type indicator.
  const symbolSpan = document.createElement('span');
  const symbol = String.fromCodePoint(kind.codePointAt(0) - 'a'.codePointAt(0) + 'ⓐ'.codePointAt(0));
  symbolSpan.title = kind; // tooltip
  symbolSpan.append(`${symbol} `);
  specItem.append(symbolSpan);

  // Link name to declaration.
  const specName = document.createElement('a');
  specItem.appendChild(specName);
  specName.textContent = ` ${specData.Name}`;
  specName.addEventListener('click', () => httpGET(specData.URL));

  return specItem;
}

/** createRefItem creates an <li> element for a refJSON object (a reference). */
function createRefItem(refData) {
  const refItem = document.createElement('li');
  refItem.className = 'ref-node';

  // Link (from -> to) to the reference in from.
  const refLink = document.createElement('a');
  refItem.appendChild(refLink);
  refLink.addEventListener('click', () => httpGET(refData.URL));
  refLink.textContent = "${refData.From} ➤ ${refData.To}";

  return refItem;
}

/** componentColors is a palette of dark, high-contrast colors. */
const componentColors = [
  "#298429",
  "#4B4B8F",
  "#AD2C2C",
  "#A62CA6",
  "#6E65AF",
  "#D15050",
  "#2CA6A6",
  "#C55656",
  "#7B8C58",
  "#587676",
  "#B95EE1",
  "#AF6D41",
];


================================================
FILE: gopls/internal/server/call_hierarchy.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) PrepareCallHierarchy(ctx context.Context, params *protocol.CallHierarchyPrepareParams) ([]protocol.CallHierarchyItem, error) {
	ctx, done := event.Start(ctx, "server.PrepareCallHierarchy")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.PrepareCallHierarchy(ctx, snapshot, fh, params.Range)
	}
	return nil, nil // empty result
}

func (s *server) IncomingCalls(ctx context.Context, params *protocol.CallHierarchyIncomingCallsParams) ([]protocol.CallHierarchyIncomingCall, error) {
	ctx, done := event.Start(ctx, "server.IncomingCalls")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.Item.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.IncomingCalls(ctx, snapshot, fh, params.Item.Range)
	}
	return nil, nil // empty result
}

func (s *server) OutgoingCalls(ctx context.Context, params *protocol.CallHierarchyOutgoingCallsParams) ([]protocol.CallHierarchyOutgoingCall, error) {
	ctx, done := event.Start(ctx, "server.OutgoingCalls")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.Item.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.OutgoingCalls(ctx, snapshot, fh, params.Item.Range.Start)
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/code_action.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
)

func (s *server) CodeAction(ctx context.Context, params *protocol.CodeActionParams) ([]protocol.CodeAction, error) {
	ctx, done := event.Start(ctx, "server.CodeAction")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	uri := fh.URI()
	kind := snapshot.FileKind(fh)

	// Determine the supported code action kinds for this file.
	//
	// We interpret CodeActionKinds hierarchically, so refactor.rewrite
	// subsumes refactor.rewrite.change_quote, for example,
	// and "" (protocol.Empty) subsumes all kinds.
	// See ../protocol/codeactionkind.go for some code action theory.
	//
	// The Context.Only field specifies which code actions
	// the client wants. According to LSP 3.18 textDocument_codeAction,
	// an Only=[] should be interpreted as Only=["quickfix"]:
	//
	//   "In version 1.0 of the protocol, there weren’t any
	//   source or refactoring code actions. Code actions
	//   were solely used to (quick) fix code, not to
	//   write/rewrite code. So if a client asks for code
	//   actions without any kind, the standard quick fix
	//   code actions should be returned."
	//
	// However, this would deny clients (e.g. Vim+coc.nvim,
	// Emacs+eglot, and possibly others) the easiest and most
	// natural way of querying the server for the entire set of
	// available code actions. But reporting all available code
	// actions would be a nuisance for VS Code, since mere cursor
	// motion into a region with a code action (~anywhere) would
	// trigger a lightbulb usually associated with quickfixes.
	//
	// As a compromise, we use the trigger kind as a heuristic: if
	// the query was triggered by cursor motion (Automatic), we
	// respond with only quick fixes; if the query was invoked
	// explicitly (Invoked), we respond with all available
	// actions.
	codeActionKinds := make(map[protocol.CodeActionKind]bool)
	if len(params.Context.Only) > 0 {
		for _, kind := range params.Context.Only { // kind may be "" (=> all)
			codeActionKinds[kind] = true
		}
	} else {
		// No explicit kind specified.
		// Heuristic: decide based on trigger.
		if triggerKind(params) == protocol.CodeActionAutomatic {
			// e.g. cursor motion: show only quick fixes
			codeActionKinds[protocol.QuickFix] = true
		} else {
			// e.g. a menu selection (or unknown trigger kind,
			// as in our tests): show all available code actions.
			codeActionKinds[protocol.Empty] = true
		}
	}

	// enabled reports whether the specified kind of code action is required.
	enabled := func(kind protocol.CodeActionKind) bool {
		// Given "refactor.rewrite.foo", check for it,
		// then "refactor.rewrite", "refactor", then "".
		// A false map entry prunes the search for ancestors.
		//
		// If codeActionKinds contains protocol.Empty (""),
		// all kinds are enabled.
		for {
			if v, ok := codeActionKinds[kind]; ok {
				return v
			}
			if kind == "" {
				return false
			}

			// The "source.test" code action shouldn't be
			// returned to the client unless requested by
			// an exact match in Only.
			//
			// This mechanism exists to avoid a distracting
			// lightbulb (code action) on each Test function.
			// These actions are unwanted in VS Code because it
			// has Test Explorer, and in other editors because
			// the UX of executeCommand is unsatisfactory for tests:
			// it doesn't show the complete streaming output.
			// See https://github.com/joaotavora/eglot/discussions/1402
			// for a better solution. See also
			// https://github.com/golang/go/issues/67400.
			//
			// TODO(adonovan): consider instead switching on
			// codeActionTriggerKind. Perhaps other noisy Source
			// Actions should be guarded in the same way.
			if kind == settings.GoTest {
				return false // don't search ancestors
			}

			// Try the parent.
			if dot := strings.LastIndexByte(string(kind), '.'); dot >= 0 {
				kind = kind[:dot] // "refactor.foo" -> "refactor"
			} else {
				kind = "" // "refactor" -> ""
			}
		}
	}

	switch kind {
	case file.Mod:
		var actions []protocol.CodeAction

		fixes, err := s.codeActionsMatchingDiagnostics(ctx, fh.URI(), snapshot, params.Context.Diagnostics, enabled)
		if err != nil {
			return nil, err
		}

		// Group vulnerability fixes by their range, and select only the most
		// appropriate upgrades.
		//
		// TODO(rfindley): can this instead be accomplished on the diagnosis side,
		// so that code action handling remains uniform?
		vulnFixes := make(map[protocol.Range][]protocol.CodeAction)
	searchFixes:
		for _, fix := range fixes {
			for _, diag := range fix.Diagnostics {
				if diag.Source == string(cache.Govulncheck) || diag.Source == string(cache.Vulncheck) {
					vulnFixes[diag.Range] = append(vulnFixes[diag.Range], fix)
					continue searchFixes
				}
			}
			actions = append(actions, fix)
		}

		for _, fixes := range vulnFixes {
			fixes = mod.SelectUpgradeCodeActions(fixes)
			actions = append(actions, fixes...)
		}

		return actions, nil

	case file.Go:
		// diagnostic-bundled code actions
		//
		// The diagnostics already have a UI presence (e.g. squiggly underline);
		// the associated action may additionally show (in VS Code) as a lightbulb.
		// Note s.codeActionsMatchingDiagnostics returns only fixes
		// detected during the analysis phase. golang.CodeActions computes
		// extra changes that can address some diagnostics.
		actions, err := s.codeActionsMatchingDiagnostics(ctx, uri, snapshot, params.Context.Diagnostics, enabled)
		if err != nil {
			return nil, err
		}

		// computed code actions (may include quickfixes from diagnostics)
		moreActions, err := golang.CodeActions(ctx, snapshot, s.Options(), fh, params.Range, params.Context.Diagnostics, enabled, triggerKind(params))
		if err != nil {
			return nil, err
		}
		actions = append(actions, moreActions...)

		// Don't suggest most fixes for generated files, since they are generally
		// not useful and some editors may apply them automatically on save.
		// (Unfortunately there's no reliable way to distinguish fixes from
		// queries, so we must list all kinds of queries here.)
		//
		// We make an exception for OrganizeImports, because
		// (a) it is needed when making temporary experimental
		//     changes (e.g. adding logging) in generated files, and
		// (b) it doesn't report diagnostics on well-formed code, and
		//     unedited generated files must be well formed.
		if golang.IsGenerated(ctx, snapshot, uri) {
			actions = slices.DeleteFunc(actions, func(a protocol.CodeAction) bool {
				switch a.Kind {
				case settings.GoTest,
					settings.GoDoc,
					settings.GoFreeSymbols,
					settings.GoSplitPackage,
					settings.GoAssembly,
					settings.GoplsDocFeatures,
					settings.GoToggleCompilerOptDetails:
					return false // read-only query
				case settings.OrganizeImports:
					return false // fix allowed in generated files (see #73959)
				}
				return true // potential write operation
			})
		}

		return actions, nil

	default:
		// Unsupported file kind for a code action.
		return nil, nil
	}
}

func triggerKind(params *protocol.CodeActionParams) protocol.CodeActionTriggerKind {
	if kind := params.Context.TriggerKind; kind != nil { // (some clients omit it)
		return *kind
	}
	return protocol.CodeActionUnknownTrigger
}

// ResolveCodeAction resolves missing Edit information (that is, computes the
// details of the necessary patch) in the given code action using the provided
// Data field of the CodeAction, which should contain the raw json of a protocol.Command.
//
// This should be called by the client before applying code actions, when the
// client has code action resolve support.
//
// This feature allows capable clients to preview and selectively apply the diff
// instead of applying the whole thing unconditionally through workspace/applyEdit.
func (s *server) ResolveCodeAction(ctx context.Context, ca *protocol.CodeAction) (*protocol.CodeAction, error) {
	ctx, done := event.Start(ctx, "server.ResolveCodeAction")
	defer done()

	// Only resolve the code action if there is Data provided.
	var cmd protocol.Command
	if ca.Data != nil {
		if err := protocol.UnmarshalJSON(*ca.Data, &cmd); err != nil {
			return nil, err
		}
	}
	ca.Data = nil
	if cmd.Command != "" {
		// Try to resolve codeaction edits by running the command.
		//
		// Unfortunately, we can't simply report failure to execute the command, as
		// some clients (namely, VS Code with the Live Share extension) eagerly
		// resolve *all* code actions, and returning an error leads to spammy
		// popups. Instead, we simply set the command on the code action, and let
		// it fail if/when invoked (golang/go#75442).
		//
		// This is arguably a client-side bug, but we work around it as it causes
		// significant problems for our users.
		// https://github.com/microsoft/live-share/issues/5293
		params := &protocol.ExecuteCommandParams{
			Command:   cmd.Command,
			Arguments: cmd.Arguments,
		}
		handler := &commandHandler{
			s:      s,
			params: params,
		}
		edit, err := command.Dispatch(ctx, params, handler)
		if err != nil {
			// Resolving edits failed, so just resolve the command.
			ca.Command = &cmd
			return ca, nil
		}
		var ok bool
		if ca.Edit, ok = edit.(*protocol.WorkspaceEdit); !ok {
			return nil, fmt.Errorf("unable to resolve code action %q", ca.Title)
		}
	}
	return ca, nil
}

// codeActionsMatchingDiagnostics creates code actions for the
// provided diagnostics, by unmarshalling actions bundled in the
// protocol.Diagnostic.Data field or, if there were none, by creating
// actions from edits associated with a matching Diagnostic from the
// set of stored diagnostics for this file.
func (s *server) codeActionsMatchingDiagnostics(ctx context.Context, uri protocol.DocumentURI, snapshot *cache.Snapshot, pds []protocol.Diagnostic, enabled func(protocol.CodeActionKind) bool) ([]protocol.CodeAction, error) {
	var actions []protocol.CodeAction
	var unbundled []protocol.Diagnostic // diagnostics without bundled code actions in their Data field
	for _, pd := range pds {
		bundled, err := cache.BundledLazyFixes(pd)
		if err != nil {
			return nil, err
		}
		if len(bundled) > 0 {
			for _, fix := range bundled {
				if enabled(fix.Kind) {
					actions = append(actions, fix)
				}
			}
		} else {
			// No bundled actions: keep searching for a match.
			unbundled = append(unbundled, pd)
		}
	}

	for _, pd := range unbundled {
		for _, sd := range s.findMatchingDiagnostics(uri, pd) {
			diagActions, err := codeActionsForDiagnostic(ctx, snapshot, sd, &pd, enabled)
			if err != nil {
				return nil, err
			}
			actions = append(actions, diagActions...)
		}
	}
	return actions, nil
}

func codeActionsForDiagnostic(ctx context.Context, snapshot *cache.Snapshot, sd *cache.Diagnostic, pd *protocol.Diagnostic, enabled func(protocol.CodeActionKind) bool) ([]protocol.CodeAction, error) {
	var actions []protocol.CodeAction
	for _, fix := range sd.SuggestedFixes {
		if !enabled(fix.ActionKind) {
			continue
		}
		var changes []protocol.DocumentChange
		for uri, edits := range fix.Edits {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return nil, err
			}
			change := protocol.DocumentChangeEdit(fh, edits)
			changes = append(changes, change)
		}
		actions = append(actions, protocol.CodeAction{
			Title:       fix.Title,
			Kind:        fix.ActionKind,
			Edit:        protocol.NewWorkspaceEdit(changes...),
			Command:     fix.Command,
			Diagnostics: []protocol.Diagnostic{*pd},
		})
	}
	return actions, nil
}

func (s *server) findMatchingDiagnostics(uri protocol.DocumentURI, pd protocol.Diagnostic) []*cache.Diagnostic {
	s.diagnosticsMu.Lock()
	defer s.diagnosticsMu.Unlock()

	var sds []*cache.Diagnostic
	if fileDiags := s.diagnostics[uri]; fileDiags != nil {
		for _, viewDiags := range fileDiags.byView {
			for _, sd := range viewDiags.diagnostics {
				// extra space may have been trimmed when
				// converting to protocol.Diagnostic
				sameDiagnostic := pd.Message == strings.TrimSpace(sd.Message) &&
					protocol.CompareRange(pd.Range, sd.Range) == 0 &&
					pd.Source == string(sd.Source)

				if sameDiagnostic {
					sds = append(sds, sd)
				}
			}
		}
	}
	return sds
}

func (s *server) getSupportedCodeActions() []protocol.CodeActionKind {
	allCodeActionKinds := make(map[protocol.CodeActionKind]struct{})
	for _, kinds := range s.Options().SupportedCodeActions {
		for kind := range kinds {
			allCodeActionKinds[kind] = struct{}{}
		}
	}
	var result []protocol.CodeActionKind
	for kind := range allCodeActionKinds {
		result = append(result, kind)
	}
	slices.Sort(result)
	return result
}

type unit = struct{}


================================================
FILE: gopls/internal/server/code_lens.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"encoding/json"
	"fmt"
	"sort"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
)

type codeLensMetadata struct {
	Source string `json:"source"`
}

// CodeLens reports the set of available CodeLenses
// (range-associated commands) in the given file.
func (s *server) CodeLens(ctx context.Context, params *protocol.CodeLensParams) ([]protocol.CodeLens, error) {
	ctx, done := event.Start(ctx, "server.CodeLens", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	var lensFuncs map[settings.CodeLensSource]cache.CodeLensSourceFunc
	switch snapshot.FileKind(fh) {
	case file.Mod:
		lensFuncs = mod.CodeLensSources()
	case file.Go:
		lensFuncs = golang.CodeLensSources()
	default:
		// Unsupported file kind for a code lens.
		return nil, nil
	}
	var lenses []protocol.CodeLens
	for kind, lensFunc := range lensFuncs {
		if !snapshot.Options().Codelenses[kind] {
			continue
		}
		added, err := lensFunc(ctx, snapshot, fh)
		// Code lens is called on every keystroke, so we should just operate in
		// a best-effort mode, ignoring errors.
		if err != nil {
			event.Error(ctx, fmt.Sprintf("code lens %s failed", kind), err)
			continue
		}
		lenses = append(lenses, added...)
	}
	for i := range lenses {
		if lenses[i].Command == nil {
			continue
		}
		meta := codeLensMetadata{Source: "codelens"}
		metaBytes, err := json.Marshal(meta)
		if err != nil {
			event.Error(ctx, "failed to marshal codelens metadata", err)
			continue
		}
		lenses[i].Command.Arguments = append(lenses[i].Command.Arguments, json.RawMessage(metaBytes))
	}
	sort.Slice(lenses, func(i, j int) bool {
		a, b := lenses[i], lenses[j]
		if cmp := protocol.CompareRange(a.Range, b.Range); cmp != 0 {
			return cmp < 0
		}
		return a.Command.Command < b.Command.Command
	})
	return lenses, nil
}


================================================
FILE: gopls/internal/server/command.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"maps"
	"os"
	"path/filepath"
	"regexp"
	"runtime"
	"runtime/pprof"
	"slices"
	"sort"
	"strings"
	"sync"

	"github.com/fatih/gomodifytags/modifytags"
	"golang.org/x/mod/modfile"
	"golang.org/x/telemetry/counter"
	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/tokeninternal"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/scan"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/xcontext"
)

func (s *server) ExecuteCommand(ctx context.Context, params *protocol.ExecuteCommandParams) (any, error) {
	ctx, done := event.Start(ctx, "server.ExecuteCommand")
	defer done()

	// For test synchronization, always create a progress notification.
	//
	// This may be in addition to user-facing progress notifications created in
	// the course of command execution.
	if s.Options().VerboseWorkDoneProgress {
		work := s.progress.Start(ctx, params.Command, "Verbose: running command...", nil, nil)
		defer work.End(ctx, "Done.")
	}

	if !slices.Contains(s.Options().SupportedCommands, params.Command) {
		return nil, fmt.Errorf("%s is not a supported command", params.Command)
	}

	if len(params.Arguments) > 0 {
		last := params.Arguments[len(params.Arguments)-1]
		var meta struct {
			Source string `json:"source"`
		}
		if err := json.Unmarshal(last, &meta); err == nil && meta.Source != "" {
			commandName := strings.TrimPrefix(params.Command, "gopls.")
			counterName := fmt.Sprintf("gopls/cmd/source:%s-%s", commandName, meta.Source)
			counter.New(counterName).Inc()
			params.Arguments = params.Arguments[:len(params.Arguments)-1]
		}
	}

	handler := &commandHandler{
		s:      s,
		params: params,
	}
	return command.Dispatch(ctx, params, handler)
}

type commandHandler struct {
	s      *server
	params *protocol.ExecuteCommandParams
}

func (h *commandHandler) Modules(ctx context.Context, args command.ModulesArgs) (command.ModulesResult, error) {
	// keepModule filters modules based on the command args
	keepModule := func(goMod protocol.DocumentURI) bool {
		// Does the directory enclose the view's go.mod file?
		if !args.Dir.Encloses(goMod) {
			return false
		}

		// Calculate the relative path
		rel, err := filepath.Rel(args.Dir.Path(), goMod.Path())
		if err != nil {
			return false // "can't happen" (see prior Encloses check)
		}

		assert(goMod.Base() == "go.mod", fmt.Sprintf("invalid go.mod path: want go.mod, got %q", goMod.Path()))

		// Invariant: rel is a relative path without "../" segments and the last
		// segment is "go.mod"
		nparts := strings.Count(rel, string(filepath.Separator))
		return args.MaxDepth < 0 || nparts <= args.MaxDepth
	}

	// Views may include:
	//   - go.work views containing one or more modules each;
	//   - go.mod views containing a single module each;
	//   - GOPATH and/or ad hoc views containing no modules.
	//
	// Retrieving a view via the request path would only work for a
	// non-recursive query for a go.mod view, and even in that case
	// [Session.SnapshotOf] doesn't work on directories. Thus we check every
	// view.
	var result command.ModulesResult
	seen := map[protocol.DocumentURI]bool{}
	for _, v := range h.s.session.Views() {
		s, release, err := v.Snapshot()
		if err != nil {
			return command.ModulesResult{}, err
		}
		defer release()

		for _, modFile := range v.ModFiles() {
			if !keepModule(modFile) {
				continue
			}

			// Deduplicate
			if seen[modFile] {
				continue
			}
			seen[modFile] = true

			fh, err := s.ReadFile(ctx, modFile)
			if err != nil {
				return command.ModulesResult{}, err
			}
			mod, err := s.ParseMod(ctx, fh)
			if err != nil {
				return command.ModulesResult{}, err
			}
			if mod.File.Module == nil {
				continue // syntax contains errors
			}
			result.Modules = append(result.Modules, command.Module{
				Path:    mod.File.Module.Mod.Path,
				Version: mod.File.Module.Mod.Version,
				GoMod:   mod.URI,
			})
		}
	}
	return result, nil
}

func (h *commandHandler) Packages(ctx context.Context, args command.PackagesArgs) (command.PackagesResult, error) {
	// Convert file arguments into directories
	dirs := make([]protocol.DocumentURI, len(args.Files))
	for i, file := range args.Files {
		if filepath.Ext(file.Path()) == ".go" {
			dirs[i] = file.Dir()
		} else {
			dirs[i] = file
		}
	}

	keepPackage := func(pkg *metadata.Package) bool {
		for _, file := range pkg.GoFiles {
			for _, dir := range dirs {
				if file.Dir() == dir || args.Recursive && dir.Encloses(file) {
					return true
				}
			}
		}
		return false
	}

	result := command.PackagesResult{
		Module: make(map[string]command.Module),
	}

	err := h.run(ctx, commandConfig{
		progress: "Packages",
	}, func(ctx context.Context, _ commandDeps) error {
		for _, view := range h.s.session.Views() {
			snapshot, release, err := view.Snapshot()
			if err != nil {
				return err
			}
			defer release()

			metas, err := snapshot.WorkspaceMetadata(ctx)
			if err != nil {
				return err
			}

			// Filter out unwanted packages
			metas = slices.DeleteFunc(metas, func(meta *metadata.Package) bool {
				return meta.IsIntermediateTestVariant() ||
					!keepPackage(meta)
			})

			start := len(result.Packages)
			for _, meta := range metas {
				var mod command.Module
				if meta.Module != nil {
					mod = command.Module{
						Path:    meta.Module.Path,
						Version: meta.Module.Version,
						GoMod:   protocol.URIFromPath(meta.Module.GoMod),
					}
					result.Module[mod.Path] = mod // Overwriting is ok
				}

				result.Packages = append(result.Packages, command.Package{
					Path:       string(meta.PkgPath),
					ForTest:    string(meta.ForTest),
					ModulePath: mod.Path,
				})
			}

			if args.Mode&command.NeedTests == 0 {
				continue
			}

			// Make a single request to the index (per snapshot) to minimize the
			// performance hit
			var ids []cache.PackageID
			for _, meta := range metas {
				ids = append(ids, meta.ID)
			}

			allTests, err := snapshot.Tests(ctx, ids...)
			if err != nil {
				return err
			}

			for i, tests := range allTests {
				pkg := &result.Packages[start+i]
				fileByPath := map[protocol.DocumentURI]*command.TestFile{}
				for _, test := range tests.All() {
					test := command.TestCase{
						Name: test.Name,
						Loc:  test.Location,
					}

					file, ok := fileByPath[test.Loc.URI]
					if !ok {
						f := command.TestFile{
							URI: test.Loc.URI,
						}
						i := len(pkg.TestFiles)
						pkg.TestFiles = append(pkg.TestFiles, f)
						file = &pkg.TestFiles[i]
						fileByPath[test.Loc.URI] = file
					}
					file.Tests = append(file.Tests, test)
				}
			}
		}

		return nil
	})
	return result, err
}

func (h *commandHandler) MaybePromptForTelemetry(ctx context.Context) error {
	// if the server's TelemetryPrompt is true, it's likely the server already
	// handled prompting for it. Don't try to prompt again.
	if !h.s.options.TelemetryPrompt {
		go h.s.maybePromptForTelemetry(ctx, true)
	}
	return nil
}

func (*commandHandler) AddTelemetryCounters(_ context.Context, args command.AddTelemetryCountersArgs) error {
	if len(args.Names) != len(args.Values) {
		return fmt.Errorf("Names and Values must have the same length")
	}
	// invalid counter update requests will be silently dropped. (no audience)
	for i, n := range args.Names {
		v := args.Values[i]
		if n == "" || v < 0 {
			continue
		}
		counter.Add("fwd/"+n, v)
	}
	return nil
}

func (c *commandHandler) AddTest(ctx context.Context, loc protocol.Location) (*protocol.WorkspaceEdit, error) {
	var result *protocol.WorkspaceEdit
	err := c.run(ctx, commandConfig{
		forURI: loc.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		if deps.snapshot.FileKind(deps.fh) != file.Go {
			return fmt.Errorf("can't add test for non-Go file")
		}
		docedits, show, err := golang.AddTestForFunc(ctx, deps.snapshot, loc)
		if err != nil {
			return err
		}
		if err := applyChanges(ctx, c.s.client, docedits); err != nil {
			return err
		}

		if show != nil {
			showDocumentImpl(ctx, c.s.client, protocol.URI(show.URI), &show.Range, c.s.options)
		}
		return nil
	})
	return result, err
}

func (c *commandHandler) LSP(ctx context.Context, param command.LSPArgs) (any, error) {
	response, valid, err := protocol.ServerDispatchCall(ctx, c.s, param.Method, param.Param)
	if !valid {
		return nil, fmt.Errorf("method %s does not exist", param.Method)
	}

	return response, err
}

// commandConfig configures common command set-up and execution.
type commandConfig struct {
	requireSave   bool                           // whether all files must be saved for the command to work
	progress      string                         // title to use for progress reporting. If empty, no progress will be reported.
	progressStyle settings.WorkDoneProgressStyle // style information for client-side progress display.
	forView       string                         // view to resolve to a snapshot; incompatible with forURI
	forURI        protocol.DocumentURI           // URI to resolve to a snapshot. If unset, snapshot will be nil.
}

// commandDeps is evaluated from a commandConfig. Note that not all fields may
// be populated, depending on which configuration is set. See comments in-line
// for details.
type commandDeps struct {
	snapshot *cache.Snapshot    // present if cfg.forURI or forView was set
	fh       file.Handle        // present if cfg.forURI was set
	work     *progress.WorkDone // present if cfg.progress was set
}

type commandFunc func(context.Context, commandDeps) error

// These strings are reported as the final WorkDoneProgressEnd message
// for each workspace/executeCommand request.
const (
	CommandCanceled  = "canceled"
	CommandFailed    = "failed"
	CommandCompleted = "completed"
)

// run performs command setup for command execution, and invokes the given run
// function. If cfg.async is set, run executes the given func in a separate
// goroutine, and returns as soon as setup is complete and the goroutine is
// scheduled.
//
// Invariant: if the resulting error is non-nil, the given run func will
// (eventually) be executed exactly once.
func (c *commandHandler) run(ctx context.Context, cfg commandConfig, run commandFunc) (err error) {
	if cfg.requireSave {
		var unsaved []string
		for _, overlay := range c.s.session.Overlays() {
			if !overlay.SameContentsOnDisk() {
				unsaved = append(unsaved, overlay.URI().Path())
			}
		}
		if len(unsaved) > 0 {
			return fmt.Errorf("All files must be saved first (unsaved: %v).", unsaved)
		}
	}
	var deps commandDeps
	var release func()
	if cfg.forURI != "" && cfg.forView != "" {
		return bug.Errorf("internal error: forURI=%q, forView=%q", cfg.forURI, cfg.forView)
	}
	if cfg.forURI != "" {
		deps.fh, deps.snapshot, release, err = c.s.session.FileOf(ctx, cfg.forURI)
		if err != nil {
			return err
		}

	} else if cfg.forView != "" {
		view, err := c.s.session.View(cfg.forView)
		if err != nil {
			return err
		}
		deps.snapshot, release, err = view.Snapshot()
		if err != nil {
			return err
		}

	} else {
		release = func() {}
	}
	// Inv: release() must be called exactly once after this point.
	// In the async case, runcmd may outlive run().

	ctx, cancel := context.WithCancel(xcontext.Detach(ctx))
	if cfg.progress != "" {
		header := ""
		if _, ok := c.s.options.SupportedWorkDoneProgressFormats[cfg.progressStyle]; ok && cfg.progressStyle != "" {
			header = fmt.Sprintf("style: %s\n\n", cfg.progressStyle)
		}
		deps.work = c.s.progress.Start(ctx, cfg.progress, header+"Running...", c.params.WorkDoneToken, cancel)
	}
	runcmd := func() error {
		defer release()
		defer cancel()
		err := run(ctx, deps)
		if deps.work != nil {
			switch {
			case errors.Is(err, context.Canceled):
				deps.work.End(ctx, CommandCanceled)
			case err != nil:
				event.Error(ctx, "command error", err)
				deps.work.End(ctx, CommandFailed)
			default:
				deps.work.End(ctx, CommandCompleted)
			}
		}
		return err
	}

	// For legacy reasons, gopls.run_govulncheck must run asynchronously.
	// TODO(golang/vscode-go#3572): remove this (along with the
	// gopls.run_govulncheck command entirely) once VS Code only uses the new
	// gopls.vulncheck command.
	if c.params.Command == "gopls.run_govulncheck" {
		if cfg.progress == "" {
			log.Fatalf("asynchronous command gopls.run_govulncheck does not enable progress reporting")
		}
		go func() {
			if err := runcmd(); err != nil {
				showMessage(ctx, c.s.client, protocol.Error, err.Error())
			}
		}()
		return nil
	}

	return runcmd()
}

func (c *commandHandler) ApplyFix(ctx context.Context, args command.ApplyFixArgs) (*protocol.WorkspaceEdit, error) {
	var result *protocol.WorkspaceEdit
	err := c.run(ctx, commandConfig{
		// Note: no progress here. Applying fixes should be quick.
		forURI: args.Location.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		changes, err := golang.ApplyFix(ctx, args.Fix, deps.snapshot, deps.fh, args.Location.Range)
		if err != nil {
			return err
		}
		wsedit := protocol.NewWorkspaceEdit(changes...)
		if args.ResolveEdits {
			result = wsedit
			return nil
		}
		return applyChanges(ctx, c.s.client, changes)
	})
	return result, err
}

func (c *commandHandler) RegenerateCgo(ctx context.Context, args command.URIArg) error {
	return c.run(ctx, commandConfig{
		progress: "Regenerating Cgo",
	}, func(ctx context.Context, _ commandDeps) error {
		return c.modifyState(ctx, FromRegenerateCgo, func() (*cache.Snapshot, func(), error) {
			// Resetting the view causes cgo to be regenerated via `go list`.
			v, err := c.s.session.ResetView(ctx, args.URI)
			if err != nil {
				return nil, nil, err
			}
			return v.Snapshot()
		})
	})
}

// modifyState performs an operation that modifies the snapshot state.
//
// It causes a snapshot diagnosis for the provided ModificationSource.
func (c *commandHandler) modifyState(ctx context.Context, source ModificationSource, work func() (*cache.Snapshot, func(), error)) error {
	var wg sync.WaitGroup // tracks work done on behalf of this function, incl. diagnostics
	wg.Add(1)
	defer wg.Done()

	// Track progress on this operation for testing.
	if c.s.Options().VerboseWorkDoneProgress {
		work := c.s.progress.Start(ctx, DiagnosticWorkTitle(source), "Calculating file diagnostics...", nil, nil)
		go func() {
			wg.Wait()
			work.End(ctx, "Done.")
		}()
	}
	snapshot, release, err := work()
	if err != nil {
		return err
	}
	wg.Go(func() {
		// Diagnosing with the background context ensures new snapshots are fully
		// diagnosed.
		c.s.diagnoseSnapshot(snapshot.BackgroundContext(), snapshot, nil, 0)
		release()
	})
	return nil
}

func (c *commandHandler) CheckUpgrades(ctx context.Context, args command.CheckUpgradesArgs) error {
	return c.run(ctx, commandConfig{
		forURI:   args.URI,
		progress: "Checking for upgrades",
	}, func(ctx context.Context, deps commandDeps) error {
		return c.modifyState(ctx, FromCheckUpgrades, func() (*cache.Snapshot, func(), error) {
			upgrades, err := c.s.getUpgrades(ctx, deps.snapshot, args.URI, args.Modules)
			if err != nil {
				return nil, nil, err
			}
			return c.s.session.InvalidateView(ctx, deps.snapshot.View(), cache.StateChange{
				ModuleUpgrades: map[protocol.DocumentURI]map[string]string{args.URI: upgrades},
			})
		})
	})
}

func (c *commandHandler) AddDependency(ctx context.Context, args command.DependencyArgs) error {
	return c.GoGetModule(ctx, args)
}

func (c *commandHandler) UpgradeDependency(ctx context.Context, args command.DependencyArgs) error {
	return c.GoGetModule(ctx, args)
}

func (c *commandHandler) ResetGoModDiagnostics(ctx context.Context, args command.ResetGoModDiagnosticsArgs) error {
	return c.run(ctx, commandConfig{
		forURI: args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		return c.modifyState(ctx, FromResetGoModDiagnostics, func() (*cache.Snapshot, func(), error) {
			return c.s.session.InvalidateView(ctx, deps.snapshot.View(), cache.StateChange{
				ModuleUpgrades: map[protocol.DocumentURI]map[string]string{
					deps.fh.URI(): nil,
				},
				Vulns: map[protocol.DocumentURI]*vulncheck.Result{
					deps.fh.URI(): nil,
				},
			})
		})
	})
}

func (c *commandHandler) GoGetModule(ctx context.Context, args command.DependencyArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Running go get",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		return c.s.runGoModUpdateCommands(ctx, deps.snapshot, args.URI, func(invoke func(...string) (*bytes.Buffer, error)) error {
			return runGoGetModule(invoke, args.AddRequire, args.GoCmdArgs)
		})
	})
}

// TODO(rFindley): UpdateGoSum, Tidy, and Vendor could probably all be one command.
func (c *commandHandler) UpdateGoSum(ctx context.Context, args command.URIArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Updating go.sum",
	}, func(ctx context.Context, _ commandDeps) error {
		for _, uri := range args.URIs {
			fh, snapshot, release, err := c.s.session.FileOf(ctx, uri)
			if err != nil {
				return err
			}
			defer release()
			if err := c.s.runGoModUpdateCommands(ctx, snapshot, fh.URI(), func(invoke func(...string) (*bytes.Buffer, error)) error {
				_, err := invoke("list", "all")
				return err
			}); err != nil {
				return err
			}
		}
		return nil
	})
}

func (c *commandHandler) Tidy(ctx context.Context, args command.URIArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Running go mod tidy",
	}, func(ctx context.Context, _ commandDeps) error {
		for _, uri := range args.URIs {
			fh, snapshot, release, err := c.s.session.FileOf(ctx, uri)
			if err != nil {
				return err
			}
			defer release()
			if err := c.s.runGoModUpdateCommands(ctx, snapshot, fh.URI(), func(invoke func(...string) (*bytes.Buffer, error)) error {
				_, err := invoke("mod", "tidy")
				return err
			}); err != nil {
				return err
			}
		}
		return nil
	})
}

func (c *commandHandler) Vendor(ctx context.Context, args command.URIArg) error {
	return c.run(ctx, commandConfig{
		requireSave: true, // TODO(adonovan): probably not needed; but needs a test.
		progress:    "Running go mod vendor",
		forURI:      args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		// Use RunGoCommandPiped here so that we don't compete with any other go
		// command invocations. go mod vendor deletes modules.txt before recreating
		// it, and therefore can run into file locking issues on Windows if that
		// file is in use by another process, such as go list.
		//
		// If golang/go#44119 is resolved, go mod vendor will instead modify
		// modules.txt in-place. In that case we could theoretically allow this
		// command to run concurrently.
		stderr := new(bytes.Buffer)
		inv, cleanupInvocation, err := deps.snapshot.GoCommandInvocation(cache.NetworkOK, args.URI.DirPath(), "mod", []string{"vendor"})
		if err != nil {
			return err
		}
		defer cleanupInvocation()
		err = deps.snapshot.View().GoCommandRunner().RunPiped(ctx, *inv, &bytes.Buffer{}, stderr)
		if err != nil {
			return fmt.Errorf("running go mod vendor failed: %v\nstderr:\n%s", err, stderr.String())
		}
		return nil
	})
}

func (c *commandHandler) EditGoDirective(ctx context.Context, args command.EditGoDirectiveArgs) error {
	return c.run(ctx, commandConfig{
		requireSave: true, // if go.mod isn't saved it could cause a problem
		forURI:      args.URI,
	}, func(ctx context.Context, _ commandDeps) error {
		fh, snapshot, release, err := c.s.session.FileOf(ctx, args.URI)
		if err != nil {
			return err
		}
		defer release()
		if err := c.s.runGoModUpdateCommands(ctx, snapshot, fh.URI(), func(invoke func(...string) (*bytes.Buffer, error)) error {
			_, err := invoke("mod", "edit", "-go", args.Version)
			return err
		}); err != nil {
			return err
		}
		return nil
	})
}

func (c *commandHandler) RemoveDependency(ctx context.Context, args command.RemoveDependencyArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Removing dependency",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		// See the documentation for OnlyDiagnostic.
		//
		// TODO(rfindley): In Go 1.17+, we will be able to use the go command
		// without checking if the module is tidy.
		if args.OnlyDiagnostic {
			return c.s.runGoModUpdateCommands(ctx, deps.snapshot, args.URI, func(invoke func(...string) (*bytes.Buffer, error)) error {
				if err := runGoGetModule(invoke, false, []string{args.ModulePath + "@none"}); err != nil {
					return err
				}
				_, err := invoke("mod", "tidy")
				return err
			})
		}
		pm, err := deps.snapshot.ParseMod(ctx, deps.fh)
		if err != nil {
			return err
		}
		edits, err := dropDependency(pm, args.ModulePath)
		if err != nil {
			return err
		}
		return applyChanges(ctx, c.s.client, []protocol.DocumentChange{protocol.DocumentChangeEdit(deps.fh, edits)})
	})
}

// dropDependency returns the edits to remove the given require from the go.mod
// file.
func dropDependency(pm *cache.ParsedModule, modulePath string) ([]protocol.TextEdit, error) {
	// We need a private copy of the parsed go.mod file, since we're going to
	// modify it.
	copied, err := modfile.Parse("", pm.Mapper.Content, nil)
	if err != nil {
		return nil, err
	}
	if err := copied.DropRequire(modulePath); err != nil {
		return nil, err
	}
	copied.Cleanup()
	newContent, err := copied.Format()
	if err != nil {
		return nil, err
	}
	// Calculate the edits to be made due to the change.
	diff := diff.Bytes(pm.Mapper.Content, newContent)
	return protocol.EditsFromDiffEdits(pm.Mapper, diff)
}

func (c *commandHandler) Doc(ctx context.Context, args command.DocArgs) (protocol.URI, error) {
	if args.Location.URI == "" {
		return "", errors.New("missing location URI")
	}

	var result protocol.URI
	err := c.run(ctx, commandConfig{
		progress: "", // the operation should be fast
		forURI:   args.Location.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		pkg, pgf, err := golang.NarrowestPackageForFile(ctx, deps.snapshot, args.Location.URI)
		if err != nil {
			return err
		}
		start, end, err := pgf.RangePos(args.Location.Range)
		if err != nil {
			return err
		}

		// Start web server.
		web, err := c.s.getWeb()
		if err != nil {
			return err
		}

		// Compute package path and optional symbol fragment
		// (e.g. "#Buffer.Len") from the selection.
		pkgpath, fragment, _ := golang.DocFragment(pkg, pgf, start, end)

		// Direct the client to open the /pkg page.
		result = web.PkgURL(deps.snapshot.View().ID(), pkgpath, fragment)
		if args.ShowDocument {
			openClientBrowser(ctx, c.s.client, "Doc", result, c.s.Options())
		}

		return nil
	})
	return result, err
}

func (c *commandHandler) RunTests(ctx context.Context, args command.RunTestsArgs) error {
	return c.run(ctx, commandConfig{
		progress:    "Running go test", // (asynchronous)
		requireSave: true,              // go test honors overlays, but tests themselves cannot
		forURI:      args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		jsonrpc2.Async(ctx) // don't block RPCs behind this command, since it can take a while
		return c.runTests(ctx, deps.snapshot, deps.work, args.URI, args.Tests, args.Benchmarks)
	})
}

func (c *commandHandler) runTests(ctx context.Context, snapshot *cache.Snapshot, work *progress.WorkDone, uri protocol.DocumentURI, tests, benchmarks []string) error {
	// TODO: fix the error reporting when this runs async.
	meta, err := snapshot.NarrowestMetadataForFile(ctx, uri)
	if err != nil {
		return err
	}
	pkgPath := string(meta.ForTest)

	// create output
	buf := &bytes.Buffer{}
	ew := progress.NewEventWriter(ctx, "test")
	out := io.MultiWriter(ew, progress.NewWorkDoneWriter(ctx, work), buf)

	// Run `go test -run Func` on each test.
	var failedTests int
	for _, funcName := range tests {
		args := []string{pkgPath, "-v", "-count=1", fmt.Sprintf("-run=^%s$", regexp.QuoteMeta(funcName))}
		inv, cleanupInvocation, err := snapshot.GoCommandInvocation(cache.NoNetwork, uri.DirPath(), "test", args)
		if err != nil {
			return err
		}
		defer cleanupInvocation()
		if err := snapshot.View().GoCommandRunner().RunPiped(ctx, *inv, out, out); err != nil {
			if errors.Is(err, context.Canceled) {
				return err
			}
			failedTests++
		}
	}

	// Run `go test -run=^$ -bench Func` on each test.
	var failedBenchmarks int
	for _, funcName := range benchmarks {
		inv, cleanupInvocation, err := snapshot.GoCommandInvocation(cache.NoNetwork, uri.DirPath(), "test", []string{
			pkgPath, "-v", "-run=^$", fmt.Sprintf("-bench=^%s$", regexp.QuoteMeta(funcName)),
		})
		if err != nil {
			return err
		}
		defer cleanupInvocation()
		if err := snapshot.View().GoCommandRunner().RunPiped(ctx, *inv, out, out); err != nil {
			if errors.Is(err, context.Canceled) {
				return err
			}
			failedBenchmarks++
		}
	}

	var title string
	if len(tests) > 0 && len(benchmarks) > 0 {
		title = "tests and benchmarks"
	} else if len(tests) > 0 {
		title = "tests"
	} else if len(benchmarks) > 0 {
		title = "benchmarks"
	} else {
		return errors.New("No functions were provided")
	}
	message := fmt.Sprintf("all %s passed", title)
	if failedTests > 0 && failedBenchmarks > 0 {
		message = fmt.Sprintf("%d / %d tests failed and %d / %d benchmarks failed", failedTests, len(tests), failedBenchmarks, len(benchmarks))
	} else if failedTests > 0 {
		message = fmt.Sprintf("%d / %d tests failed", failedTests, len(tests))
	} else if failedBenchmarks > 0 {
		message = fmt.Sprintf("%d / %d benchmarks failed", failedBenchmarks, len(benchmarks))
	}
	if failedTests > 0 || failedBenchmarks > 0 {
		message += "\n" + buf.String()
	}

	showMessage(ctx, c.s.client, protocol.Info, message)

	if failedTests > 0 || failedBenchmarks > 0 {
		return errors.New("gopls.test command failed")
	}
	return nil
}

func (c *commandHandler) Generate(ctx context.Context, args command.GenerateArgs) error {
	title := "Running go generate ."
	if args.Recursive {
		title = "Running go generate ./..."
	}
	return c.run(ctx, commandConfig{
		requireSave: true, // commands executed by go generate cannot honor overlays
		progress:    title,
		forURI:      args.Dir,
	}, func(ctx context.Context, deps commandDeps) error {
		er := progress.NewEventWriter(ctx, "generate")

		pattern := "."
		if args.Recursive {
			pattern = "./..."
		}
		inv, cleanupInvocation, err := deps.snapshot.GoCommandInvocation(cache.NetworkOK, args.Dir.Path(), "generate", []string{"-x", pattern})
		if err != nil {
			return err
		}
		defer cleanupInvocation()
		stderr := io.MultiWriter(er, progress.NewWorkDoneWriter(ctx, deps.work))
		if err := deps.snapshot.View().GoCommandRunner().RunPiped(ctx, *inv, er, stderr); err != nil {
			return err
		}
		return nil
	})
}

func (c *commandHandler) GoGetPackage(ctx context.Context, args command.GoGetPackageArgs) error {
	return c.run(ctx, commandConfig{
		forURI:   args.URI,
		progress: "Running go get",
	}, func(ctx context.Context, deps commandDeps) error {
		snapshot := deps.snapshot
		modURI := snapshot.GoModForFile(args.URI)
		if modURI == "" {
			return fmt.Errorf("no go.mod file found for %s", args.URI)
		}
		tempDir, cleanupModDir, err := cache.TempModDir(ctx, snapshot, modURI)
		if err != nil {
			return fmt.Errorf("creating a temp go.mod: %v", err)
		}
		defer cleanupModDir()

		inv, cleanupInvocation, err := snapshot.GoCommandInvocation(cache.NetworkOK, modURI.DirPath(), "list",
			[]string{"-f", "{{.Module.Path}}@{{.Module.Version}}", "-mod=mod", "-modfile=" + filepath.Join(tempDir, "go.mod"), args.Pkg},
			"GOWORK=off",
		)
		if err != nil {
			return err
		}
		defer cleanupInvocation()
		stdout, err := snapshot.View().GoCommandRunner().Run(ctx, *inv)
		if err != nil {
			return err
		}
		ver := strings.TrimSpace(stdout.String())
		return c.s.runGoModUpdateCommands(ctx, snapshot, args.URI, func(invoke func(...string) (*bytes.Buffer, error)) error {
			if args.AddRequire {
				if err := addModuleRequire(invoke, []string{ver}); err != nil {
					return err
				}
			}
			_, err := invoke(append([]string{"get", "-d"}, args.Pkg)...)
			return err
		})
	})
}

func (s *server) runGoModUpdateCommands(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, run func(invoke func(...string) (*bytes.Buffer, error)) error) error {
	// TODO(rfindley): can/should this use findRootPattern?
	modURI := snapshot.GoModForFile(uri)
	if modURI == "" {
		return fmt.Errorf("no go.mod file found for %s", uri.Path())
	}
	newModBytes, newSumBytes, err := snapshot.RunGoModUpdateCommands(ctx, modURI, run)
	if err != nil {
		return err
	}
	sumURI := protocol.URIFromPath(strings.TrimSuffix(modURI.Path(), ".mod") + ".sum")

	modChange, err := computeEditChange(ctx, snapshot, modURI, newModBytes)
	if err != nil {
		return err
	}
	sumChange, err := computeEditChange(ctx, snapshot, sumURI, newSumBytes)
	if err != nil {
		return err
	}

	var changes []protocol.DocumentChange
	if modChange.Valid() {
		changes = append(changes, modChange)
	}
	if sumChange.Valid() {
		changes = append(changes, sumChange)
	}
	return applyChanges(ctx, s.client, changes)
}

// computeEditChange computes the edit change required to transform the
// snapshot file specified by uri to the provided new content.
// Beware: returns a DocumentChange that is !Valid() if none were necessary.
//
// If the file is not open, computeEditChange simply writes the new content to
// disk.
//
// TODO(rfindley): fix this API asymmetry. It should be up to the caller to
// write the file or apply the edits.
func computeEditChange(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, newContent []byte) (protocol.DocumentChange, error) {
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return protocol.DocumentChange{}, err
	}
	oldContent, err := fh.Content()
	if err != nil && !os.IsNotExist(err) {
		return protocol.DocumentChange{}, err
	}

	if bytes.Equal(oldContent, newContent) {
		return protocol.DocumentChange{}, nil // note: result is !Valid()
	}

	// Sending a workspace edit to a closed file causes VS Code to open the
	// file and leave it unsaved. We would rather apply the changes directly,
	// especially to go.sum, which should be mostly invisible to the user.
	if !snapshot.IsOpen(uri) {
		err := os.WriteFile(uri.Path(), newContent, 0666)
		return protocol.DocumentChange{}, err
	}

	m := protocol.NewMapper(fh.URI(), oldContent)
	diff := diff.Bytes(oldContent, newContent)
	textedits, err := protocol.EditsFromDiffEdits(m, diff)
	if err != nil {
		return protocol.DocumentChange{}, err
	}
	return protocol.DocumentChangeEdit(fh, textedits), nil
}

func applyChanges(ctx context.Context, cli protocol.Client, changes []protocol.DocumentChange) error {
	if len(changes) == 0 {
		return nil
	}
	response, err := cli.ApplyEdit(ctx, &protocol.ApplyWorkspaceEditParams{
		Edit: *protocol.NewWorkspaceEdit(changes...),
	})
	if err != nil {
		return err
	}
	if !response.Applied {
		return fmt.Errorf("edits not applied because of %s", response.FailureReason)
	}
	return nil
}

func runGoGetModule(invoke func(...string) (*bytes.Buffer, error), addRequire bool, args []string) error {
	if addRequire {
		if err := addModuleRequire(invoke, args); err != nil {
			return err
		}
	}
	_, err := invoke(append([]string{"get", "-d"}, args...)...)
	return err
}

func addModuleRequire(invoke func(...string) (*bytes.Buffer, error), args []string) error {
	// Using go get to create a new dependency results in an
	// `// indirect` comment we may not want. The only way to avoid it
	// is to add the require as direct first. Then we can use go get to
	// update go.sum and tidy up.
	_, err := invoke(append([]string{"mod", "edit", "-require"}, args...)...)
	return err
}

// TODO(rfindley): inline.
func (s *server) getUpgrades(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, modules []string) (map[string]string, error) {
	args := append([]string{"-mod=readonly", "-m", "-u", "-json"}, modules...)
	inv, cleanup, err := snapshot.GoCommandInvocation(cache.NetworkOK, uri.DirPath(), "list", args)
	if err != nil {
		return nil, err
	}
	defer cleanup()
	stdout, err := snapshot.View().GoCommandRunner().Run(ctx, *inv)
	if err != nil {
		return nil, err
	}

	upgrades := map[string]string{}
	for dec := json.NewDecoder(stdout); dec.More(); {
		mod := &gocommand.ModuleJSON{}
		if err := dec.Decode(mod); err != nil {
			return nil, err
		}
		if mod.Update == nil {
			continue
		}
		upgrades[mod.Path] = mod.Update.Version
	}
	return upgrades, nil
}

func (c *commandHandler) GCDetails(ctx context.Context, uri protocol.DocumentURI) error {
	return c.run(ctx, commandConfig{
		forURI: uri,
	}, func(ctx context.Context, deps commandDeps) error {
		return c.modifyState(ctx, FromToggleCompilerOptDetails, func() (*cache.Snapshot, func(), error) {
			// Don't blindly use "dir := deps.fh.URI().Dir()"; validate.
			meta, err := deps.snapshot.NarrowestMetadataForFile(ctx, deps.fh.URI())
			if err != nil {
				return nil, nil, err
			}
			if len(meta.CompiledGoFiles) == 0 {
				return nil, nil, fmt.Errorf("package %q does not compile file %q", meta.ID, deps.fh.URI())
			}
			dir := meta.CompiledGoFiles[0].Dir()

			want := !deps.snapshot.WantCompilerOptDetails(dir) // toggle per-directory flag
			return c.s.session.InvalidateView(ctx, deps.snapshot.View(), cache.StateChange{
				CompilerOptDetails: map[protocol.DocumentURI]bool{dir: want},
			})
		})
	})
}

func (c *commandHandler) ListKnownPackages(ctx context.Context, args command.URIArg) (command.ListKnownPackagesResult, error) {
	var result command.ListKnownPackagesResult
	err := c.run(ctx, commandConfig{
		progress: "Listing packages",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		pkgs, err := golang.KnownPackagePaths(ctx, deps.snapshot, deps.fh)
		for _, pkg := range pkgs {
			result.Packages = append(result.Packages, string(pkg))
		}
		return err
	})
	return result, err
}

func (c *commandHandler) ListImports(ctx context.Context, args command.URIArg) (command.ListImportsResult, error) {
	var result command.ListImportsResult
	err := c.run(ctx, commandConfig{
		forURI: args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		fh, err := deps.snapshot.ReadFile(ctx, args.URI)
		if err != nil {
			return err
		}
		pgf, err := deps.snapshot.ParseGo(ctx, fh, parsego.Header)
		if err != nil {
			return err
		}
		fset := tokeninternal.FileSetFor(pgf.Tok)
		for _, group := range astutil.Imports(fset, pgf.File) {
			for _, imp := range group {
				if imp.Path == nil {
					continue
				}
				var name string
				if imp.Name != nil {
					name = imp.Name.Name
				}
				result.Imports = append(result.Imports, command.FileImport{
					Path: string(metadata.UnquoteImportPath(imp)),
					Name: name,
				})
			}
		}
		meta, err := deps.snapshot.NarrowestMetadataForFile(ctx, args.URI)
		if err != nil {
			return err // e.g. cancelled
		}
		for pkgPath := range meta.DepsByPkgPath {
			result.PackageImports = append(result.PackageImports,
				command.PackageImport{Path: string(pkgPath)})
		}
		sort.Slice(result.PackageImports, func(i, j int) bool {
			return result.PackageImports[i].Path < result.PackageImports[j].Path
		})
		return nil
	})
	return result, err
}

func (c *commandHandler) AddImport(ctx context.Context, args command.AddImportArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Adding import",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		edits, err := golang.AddImport(ctx, deps.snapshot, deps.fh, args.ImportPath)
		if err != nil {
			return fmt.Errorf("could not add import: %v", err)
		}
		return applyChanges(ctx, c.s.client, []protocol.DocumentChange{protocol.DocumentChangeEdit(deps.fh, edits)})
	})
}

func (c *commandHandler) ExtractToNewFile(ctx context.Context, args protocol.Location) error {
	return c.run(ctx, commandConfig{
		progress: "Extract to a new file",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		changes, err := golang.ExtractToNewFile(ctx, deps.snapshot, deps.fh, args.Range)
		if err != nil {
			return err
		}
		return applyChanges(ctx, c.s.client, changes)
	})
}

func (c *commandHandler) StartDebugging(ctx context.Context, args command.DebuggingArgs) (result command.DebuggingResult, _ error) {
	addr := args.Addr
	if addr == "" {
		addr = "localhost:0"
	}
	di := debug.GetInstance(ctx)
	if di == nil {
		return result, errors.New("internal error: server has no debugging instance")
	}
	listenedAddr, err := di.Serve(ctx, addr)
	if err != nil {
		return result, fmt.Errorf("starting debug server: %w", err)
	}
	result.URLs = []string{"http://" + listenedAddr}
	openClientBrowser(ctx, c.s.client, "Debug", result.URLs[0], c.s.Options())
	return result, nil
}

func (c *commandHandler) StartProfile(ctx context.Context, args command.StartProfileArgs) (result command.StartProfileResult, _ error) {
	file, err := os.CreateTemp("", "gopls-profile-*")
	if err != nil {
		return result, fmt.Errorf("creating temp profile file: %v", err)
	}

	c.s.ongoingProfileMu.Lock()
	defer c.s.ongoingProfileMu.Unlock()

	if c.s.ongoingProfile != nil {
		file.Close() // ignore error
		return result, fmt.Errorf("profile already started (for %q)", c.s.ongoingProfile.Name())
	}

	if err := pprof.StartCPUProfile(file); err != nil {
		file.Close() // ignore error
		return result, fmt.Errorf("starting profile: %v", err)
	}

	c.s.ongoingProfile = file
	return result, nil
}

func (c *commandHandler) StopProfile(ctx context.Context, args command.StopProfileArgs) (result command.StopProfileResult, _ error) {
	c.s.ongoingProfileMu.Lock()
	defer c.s.ongoingProfileMu.Unlock()

	prof := c.s.ongoingProfile
	c.s.ongoingProfile = nil

	if prof == nil {
		return result, fmt.Errorf("no ongoing profile")
	}

	pprof.StopCPUProfile()
	if err := prof.Close(); err != nil {
		return result, fmt.Errorf("closing profile file: %v", err)
	}
	result.File = prof.Name()
	return result, nil
}

func (c *commandHandler) FetchVulncheckResult(ctx context.Context, arg command.URIArg) (map[protocol.DocumentURI]*vulncheck.Result, error) {
	ret := map[protocol.DocumentURI]*vulncheck.Result{}
	err := c.run(ctx, commandConfig{forURI: arg.URI}, func(ctx context.Context, deps commandDeps) error {
		if deps.snapshot.Options().Vulncheck == settings.ModeVulncheckImports {
			for _, modfile := range deps.snapshot.View().ModFiles() {
				res, err := deps.snapshot.ModVuln(ctx, modfile)
				if err != nil {
					return err
				}
				ret[modfile] = res
			}
		}
		// Overwrite if there is any govulncheck-based result.
		maps.Copy(ret, deps.snapshot.Vulnerabilities())
		return nil
	})
	return ret, err
}

const GoVulncheckCommandTitle = "govulncheck"

func (c *commandHandler) Vulncheck(ctx context.Context, args command.VulncheckArgs) (command.VulncheckResult, error) {
	if args.URI == "" {
		return command.VulncheckResult{}, errors.New("VulncheckArgs is missing URI field")
	}

	var commandResult command.VulncheckResult
	err := c.run(ctx, commandConfig{
		progress:      GoVulncheckCommandTitle,
		progressStyle: settings.WorkDoneProgressStyleLog,
		requireSave:   true, // govulncheck cannot honor overlays
		forURI:        args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		jsonrpc2.Async(ctx) // run this in parallel with other requests: vulncheck can be slow.

		workDoneWriter := progress.NewWorkDoneWriter(ctx, deps.work)
		result, err := c.s.runVulncheck(ctx, deps.snapshot, args.URI, args.Pattern, workDoneWriter)
		if err != nil {
			return err
		}
		commandResult.Result = result
		commandResult.Token = deps.work.Token()

		affecting := make(map[string]bool, len(result.Entries))
		for _, finding := range result.Findings {
			if len(finding.Trace) > 1 { // at least 2 frames if callstack exists (vulnerability, entry)
				affecting[finding.OSV] = true
			}
		}
		if len(affecting) == 0 {
			showMessage(ctx, c.s.client, protocol.Info, "No vulnerabilities found")
			return nil
		}
		affectingOSVs := make([]string, 0, len(affecting))
		for id := range affecting {
			affectingOSVs = append(affectingOSVs, id)
		}
		sort.Strings(affectingOSVs)

		showMessage(ctx, c.s.client, protocol.Warning, fmt.Sprintf("Found %v", strings.Join(affectingOSVs, ", ")))
		return nil
	})
	if err != nil {
		return command.VulncheckResult{}, err
	}
	return commandResult, nil
}

// RunGovulncheck is like Vulncheck (in fact, a copy), but is tweaked slightly
// to run asynchronously rather than return a result.
//
// This logic was copied, rather than factored out, as this implementation is
// slated for deletion.
//
// TODO(golang/vscode-go#3572)
// TODO(hxjiang): deprecate gopls.run_govulncheck.
func (c *commandHandler) RunGovulncheck(ctx context.Context, args command.VulncheckArgs) (command.RunVulncheckResult, error) {
	// Deduplicate the RunGovulncheck command so only one is running at a time.
	if !c.s.runGovulncheckInProgress.CompareAndSwap(false, true) {
		c.s.client.ShowMessage(ctx, &protocol.ShowMessageParams{
			Type:    protocol.Info,
			Message: "A govulncheck scan is already in progress.",
		})
		return command.RunVulncheckResult{}, nil
	}

	defer c.s.runGovulncheckInProgress.Store(false)

	if args.URI == "" {
		return command.RunVulncheckResult{}, errors.New("VulncheckArgs is missing URI field")
	}

	// Return the workdone token so that clients can identify when this
	// vulncheck invocation is complete.
	//
	// Since the run function executes asynchronously, we use a channel to
	// synchronize the start of the run and return the token.
	tokenChan := make(chan protocol.ProgressToken, 1)
	err := c.run(ctx, commandConfig{
		progress:    GoVulncheckCommandTitle,
		requireSave: true, // govulncheck cannot honor overlays
		forURI:      args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		tokenChan <- deps.work.Token()

		workDoneWriter := progress.NewWorkDoneWriter(ctx, deps.work)
		result, err := c.s.runVulncheck(ctx, deps.snapshot, args.URI, args.Pattern, workDoneWriter)
		if err != nil {
			return err
		}

		affecting := make(map[string]bool, len(result.Entries))
		for _, finding := range result.Findings {
			if len(finding.Trace) > 1 { // at least 2 frames if callstack exists (vulnerability, entry)
				affecting[finding.OSV] = true
			}
		}
		if len(affecting) == 0 {
			showMessage(ctx, c.s.client, protocol.Info, "No vulnerabilities found")
			return nil
		}
		affectingOSVs := make([]string, 0, len(affecting))
		for id := range affecting {
			affectingOSVs = append(affectingOSVs, id)
		}
		sort.Strings(affectingOSVs)

		showMessage(ctx, c.s.client, protocol.Warning, fmt.Sprintf("Found %v", strings.Join(affectingOSVs, ", ")))
		return nil
	})
	if err != nil {
		return command.RunVulncheckResult{}, err
	}
	select {
	case <-ctx.Done():
		return command.RunVulncheckResult{}, ctx.Err()
	case token := <-tokenChan:
		return command.RunVulncheckResult{Token: token}, nil
	}
}

// runVulncheck executes a vulnerability scan and updates the server's state.
func (s *server) runVulncheck(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, pattern string, out io.Writer) (*vulncheck.Result, error) {
	dir := uri.DirPath()
	result, err := scan.RunGovulncheck(ctx, pattern, snapshot, dir, out)
	if err != nil {
		return nil, err
	}

	// Invalidate the view to store findings in the vulnerability cache.
	newSnapshot, release, err := s.session.InvalidateView(ctx, snapshot.View(), cache.StateChange{
		Vulns: map[protocol.DocumentURI]*vulncheck.Result{uri: result},
	})
	if err != nil {
		return nil, err
	}
	defer release()

	// Diagnosing with the background context ensures new snapshots are fully
	// diagnosed.
	s.diagnoseSnapshot(newSnapshot.BackgroundContext(), newSnapshot, nil, 0)

	return result, nil
}

// MemStats implements the MemStats command. It returns an error as a
// future-proof API, but the resulting error is currently always nil.
func (c *commandHandler) MemStats(ctx context.Context) (command.MemStatsResult, error) {
	// GC a few times for stable results.
	runtime.GC()
	runtime.GC()
	runtime.GC()
	var m runtime.MemStats
	runtime.ReadMemStats(&m)
	return command.MemStatsResult{
		HeapAlloc:  m.HeapAlloc,
		HeapInUse:  m.HeapInuse,
		TotalAlloc: m.TotalAlloc,
	}, nil
}

// WorkspaceStats implements the WorkspaceStats command, reporting information
// about the current state of the loaded workspace for the current session.
func (c *commandHandler) WorkspaceStats(ctx context.Context) (command.WorkspaceStatsResult, error) {
	var res command.WorkspaceStatsResult
	res.Files = c.s.session.Cache().FileStats()

	for _, view := range c.s.session.Views() {
		vs, err := collectViewStats(ctx, view)
		if err != nil {
			return res, err
		}
		res.Views = append(res.Views, vs)
	}
	return res, nil
}

func collectViewStats(ctx context.Context, view *cache.View) (command.ViewStats, error) {
	s, release, err := view.Snapshot()
	if err != nil {
		return command.ViewStats{}, err
	}
	defer release()

	allMD, err := s.AllMetadata(ctx)
	if err != nil {
		return command.ViewStats{}, err
	}
	allPackages := collectPackageStats(allMD)

	wsMD, err := s.WorkspaceMetadata(ctx)
	if err != nil {
		return command.ViewStats{}, err
	}
	workspacePackages := collectPackageStats(wsMD)

	var ids []golang.PackageID
	for _, mp := range wsMD {
		ids = append(ids, mp.ID)
	}

	diags, err := s.PackageDiagnostics(ctx, ids...)
	if err != nil {
		return command.ViewStats{}, err
	}

	ndiags := 0
	for _, d := range diags {
		ndiags += len(d)
	}

	return command.ViewStats{
		GoCommandVersion:  view.GoVersionString(),
		AllPackages:       allPackages,
		WorkspacePackages: workspacePackages,
		Diagnostics:       ndiags,
	}, nil
}

func collectPackageStats(mps []*metadata.Package) command.PackageStats {
	var stats command.PackageStats
	stats.Packages = len(mps)
	modules := make(map[string]bool)

	for _, mp := range mps {
		n := len(mp.CompiledGoFiles)
		stats.CompiledGoFiles += n
		if n > stats.LargestPackage {
			stats.LargestPackage = n
		}
		if mp.Module != nil {
			modules[mp.Module.Path] = true
		}
	}
	stats.Modules = len(modules)

	return stats
}

// RunGoWorkCommand invokes `go work <args>` with the provided arguments.
//
// args.InitFirst controls whether to first run `go work init`. This allows a
// single command to both create and recursively populate a go.work file -- as
// of writing there is no `go work init -r`.
//
// Some thought went into implementing this command. Unlike the go.mod commands
// above, this command simply invokes the go command and relies on the client
// to notify gopls of file changes via didChangeWatchedFile notifications.
// We could instead run these commands with GOWORK set to a temp file, but that
// poses the following problems:
//   - directory locations in the resulting temp go.work file will be computed
//     relative to the directory containing that go.work. If the go.work is in a
//     tempdir, the directories will need to be translated to/from that dir.
//   - it would be simpler to use a temp go.work file in the workspace
//     directory, or whichever directory contains the real go.work file, but
//     that sets a bad precedent of writing to a user-owned directory. We
//     shouldn't start doing that.
//   - Sending workspace edits to create a go.work file would require using
//     the CreateFile resource operation, which would need to be tested in every
//     client as we haven't used it before. We don't have time for that right
//     now.
//
// Therefore, we simply require that the current go.work file is saved (if it
// exists), and delegate to the go command.
func (c *commandHandler) RunGoWorkCommand(ctx context.Context, args command.RunGoWorkArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Running go work command",
		forView:  args.ViewID,
	}, func(ctx context.Context, deps commandDeps) (runErr error) {
		snapshot := deps.snapshot
		view := snapshot.View()
		viewDir := snapshot.Folder().Path()

		if view.Type() != cache.GoWorkView && view.GoWork() != "" {
			// If we are not using an existing go.work file, GOWORK must be explicitly off.
			// TODO(rfindley): what about GO111MODULE=off?
			return fmt.Errorf("cannot modify go.work files when GOWORK=off")
		}

		var gowork string
		// If the user has explicitly set GOWORK=off, we should warn them
		// explicitly and avoid potentially misleading errors below.
		if view.GoWork() != "" {
			gowork = view.GoWork().Path()
			fh, err := snapshot.ReadFile(ctx, view.GoWork())
			if err != nil {
				return err // e.g. canceled
			}
			if !fh.SameContentsOnDisk() {
				return fmt.Errorf("must save workspace file %s before running go work commands", view.GoWork())
			}
		} else {
			if !args.InitFirst {
				// If go.work does not exist, we should have detected that and asked
				// for InitFirst.
				return bug.Errorf("internal error: cannot run go work command: required go.work file not found")
			}
			gowork = filepath.Join(viewDir, "go.work")
			if err := c.invokeGoWork(ctx, viewDir, gowork, []string{"init"}); err != nil {
				return fmt.Errorf("running `go work init`: %v", err)
			}
		}

		return c.invokeGoWork(ctx, viewDir, gowork, args.Args)
	})
}

func (c *commandHandler) invokeGoWork(ctx context.Context, viewDir, gowork string, args []string) error {
	inv := gocommand.Invocation{
		Verb:       "work",
		Args:       args,
		WorkingDir: viewDir,
		Env:        append(os.Environ(), fmt.Sprintf("GOWORK=%s", gowork)),
	}
	if _, err := c.s.session.GoCommandRunner().Run(ctx, inv); err != nil {
		return fmt.Errorf("running go work command: %v", err)
	}
	return nil
}

// showMessage causes the client to show a progress or error message.
//
// It reports whether it succeeded. If it fails, it writes an error to
// the server log, so most callers can safely ignore the result.
func showMessage(ctx context.Context, cli protocol.Client, typ protocol.MessageType, message string) bool {
	err := cli.ShowMessage(ctx, &protocol.ShowMessageParams{
		Type:    typ,
		Message: message,
	})
	if err != nil {
		event.Error(ctx, "client.showMessage: %v", err)
		return false
	}
	return true
}

// openClientBrowser causes the LSP client to open the specified URL
// in an external browser.
//
// If the client does not support window/showDocument, a window/showMessage
// request is instead used, with the format "$title: open your browser to $url".
func openClientBrowser(ctx context.Context, cli protocol.Client, title string, url protocol.URI, opts *settings.Options) {
	if opts.ShowDocumentSupported {
		showDocumentImpl(ctx, cli, url, nil, opts)
	} else {
		params := &protocol.ShowMessageParams{
			Type:    protocol.Info,
			Message: fmt.Sprintf("%s: open your browser to %s", title, url),
		}
		if err := cli.ShowMessage(ctx, params); err != nil {
			event.Error(ctx, "failed to show browser url", err)
		}
	}
}

// openClientEditor causes the LSP client to open the specified document
// and select the indicated range.
//
// Note that VS Code 1.87.2 doesn't currently raise the window; this is
// https://github.com/microsoft/vscode/issues/207634
func openClientEditor(ctx context.Context, cli protocol.Client, loc protocol.Location, opts *settings.Options) {
	if !opts.ShowDocumentSupported {
		return // no op
	}
	showDocumentImpl(ctx, cli, protocol.URI(loc.URI), &loc.Range, opts)
}

func showDocumentImpl(ctx context.Context, cli protocol.Client, url protocol.URI, rangeOpt *protocol.Range, opts *settings.Options) {
	if !opts.ShowDocumentSupported {
		return // no op
	}
	// In principle we shouldn't send a showDocument request to a
	// client that doesn't support it, as reported by
	// ShowDocumentClientCapabilities. But even clients that do
	// support it may defer the real work of opening the document
	// asynchronously, to avoid deadlocks due to rentrancy.
	//
	// For example: client sends request to server; server sends
	// showDocument to client; client opens editor; editor causes
	// new RPC to be sent to server, which is still busy with
	// previous request. (This happens in eglot.)
	//
	// So we can't rely on the success/failure information.
	// That's the reason this function doesn't return an error.

	// "External" means run the system-wide handler (e.g. open(1)
	// on macOS or xdg-open(1) on Linux) for this URL, ignoring
	// TakeFocus and Selection. Note that this may still end up
	// opening the same editor (e.g. VSCode) for a file: URL.
	res, err := cli.ShowDocument(ctx, &protocol.ShowDocumentParams{
		URI:       url,
		External:  rangeOpt == nil,
		TakeFocus: true,
		Selection: rangeOpt, // optional
	})
	if err != nil {
		event.Error(ctx, "client.showDocument: %v", err)
	} else if res != nil && !res.Success {
		event.Log(ctx, fmt.Sprintf("client declined to open document %v", url))
	}
}

func (c *commandHandler) ChangeSignature(ctx context.Context, args command.ChangeSignatureArgs) (*protocol.WorkspaceEdit, error) {
	countChangeSignature.Inc()
	var result *protocol.WorkspaceEdit
	err := c.run(ctx, commandConfig{
		forURI: args.Location.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		pkg, pgf, err := golang.NarrowestPackageForFile(ctx, deps.snapshot, args.Location.URI)
		if err != nil {
			return err
		}

		// For now, gopls only supports parameter permutation or removal.
		var perm []int
		for _, newParam := range args.NewParams {
			if newParam.NewField != "" {
				return fmt.Errorf("adding new parameters is currently unsupported")
			}
			perm = append(perm, newParam.OldIndex)
		}

		docedits, err := golang.ChangeSignature(ctx, deps.snapshot, pkg, pgf, args.Location.Range, perm)
		if err != nil {
			return err
		}
		wsedit := protocol.NewWorkspaceEdit(docedits...)
		if args.ResolveEdits {
			result = wsedit
			return nil
		}
		return applyChanges(ctx, c.s.client, docedits)
	})
	return result, err
}

func (c *commandHandler) DiagnoseFiles(ctx context.Context, args command.DiagnoseFilesArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Diagnose files",
	}, func(ctx context.Context, _ commandDeps) error {

		// TODO(rfindley): even better would be textDocument/diagnostics (golang/go#60122).
		// Though note that implementing pull diagnostics may cause some servers to
		// request diagnostics in an ad-hoc manner, and break our intentional pacing.

		ctx, done := event.Start(ctx, "commandHandler.DiagnoseFiles")
		defer done()

		snapshots := make(map[*cache.Snapshot]bool)
		for _, uri := range args.Files {
			fh, snapshot, release, err := c.s.session.FileOf(ctx, uri)
			if err != nil {
				return err
			}
			if snapshots[snapshot] || snapshot.FileKind(fh) != file.Go {
				release()
				continue
			}
			defer release()
			snapshots[snapshot] = true
		}

		var wg sync.WaitGroup
		for snapshot := range snapshots {
			wg.Go(func() {

				// Use the operation context for diagnosis, rather than
				// snapshot.BackgroundContext, because this operation does not create
				// new snapshots (so they should also be diagnosed by other means).
				c.s.diagnoseSnapshot(ctx, snapshot, nil, 0)
			})
		}
		wg.Wait()

		return nil
	})
}

func (c *commandHandler) Views(ctx context.Context) ([]command.View, error) {
	var summaries []command.View
	for _, view := range c.s.session.Views() {
		summaries = append(summaries, command.View{
			ID:         view.ID(),
			Type:       view.Type().String(),
			Root:       view.Root(),
			Folder:     view.Folder().Dir,
			EnvOverlay: view.EnvOverlay(),
		})
	}
	return summaries, nil
}

func (c *commandHandler) FreeSymbols(ctx context.Context, viewID string, loc protocol.Location) error {
	web, err := c.s.getWeb()
	if err != nil {
		return err
	}
	url := web.freesymbolsURL(viewID, loc)
	openClientBrowser(ctx, c.s.client, "Free symbols", url, c.s.Options())
	return nil
}

func (c *commandHandler) SplitPackage(ctx context.Context, viewID, packageID string) error {
	web, err := c.s.getWeb()
	if err != nil {
		return err
	}
	url := web.splitpkgURL(viewID, packageID)
	openClientBrowser(ctx, c.s.client, "SplitPackage", url, c.s.Options())
	return nil
}

func (c *commandHandler) Assembly(ctx context.Context, viewID, packageID, symbol string) error {
	web, err := c.s.getWeb()
	if err != nil {
		return err
	}
	url := web.assemblyURL(viewID, packageID, symbol)
	openClientBrowser(ctx, c.s.client, "Assembly", url, c.s.Options())
	return nil
}

func (c *commandHandler) ClientOpenURL(ctx context.Context, url string) error {
	// Fall back to "Gopls: open your browser..." if we must send a showMessage
	// request, since we don't know the context of this command.
	openClientBrowser(ctx, c.s.client, "Gopls", url, c.s.Options())
	return nil
}

func (c *commandHandler) ScanImports(ctx context.Context) error {
	for _, v := range c.s.session.Views() {
		v.ScanImports()
	}
	return nil
}

func (c *commandHandler) PackageSymbols(ctx context.Context, args command.PackageSymbolsArgs) (command.PackageSymbolsResult, error) {
	var result command.PackageSymbolsResult
	err := c.run(ctx, commandConfig{
		forURI: args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		if deps.snapshot.FileKind(deps.fh) != file.Go {
			// golang/vscode-go#3681: fail silently, to avoid spurious error popups.
			return nil
		}
		res, err := golang.PackageSymbols(ctx, deps.snapshot, args.URI)
		if err != nil {
			return err
		}
		result = res
		return nil
	})

	// sort symbols for determinism
	sort.SliceStable(result.Symbols, func(i, j int) bool {
		iv, jv := result.Symbols[i], result.Symbols[j]
		if iv.Name == jv.Name {
			return iv.Range.Start.Line < jv.Range.Start.Line
		}
		return iv.Name < jv.Name
	})

	return result, err
}

// optionsStringToMap transforms comma-separated options of the form
// "foo=bar,baz=quux" to a go map. Returns nil if any options are malformed.
func optionsStringToMap(options string) (map[string][]string, error) {
	optionsMap := make(map[string][]string)
	for item := range strings.SplitSeq(options, ",") {
		key, option, found := strings.Cut(item, "=")
		if !found {
			return nil, fmt.Errorf("invalid option %q", item)
		}
		optionsMap[key] = append(optionsMap[key], option)
	}
	return optionsMap, nil
}

func (c *commandHandler) ModifyTags(ctx context.Context, args command.ModifyTagsArgs) error {
	return c.run(ctx, commandConfig{
		progress: "Modifying tags",
		forURI:   args.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		m := &modifytags.Modification{
			Clear:        args.Clear,
			ClearOptions: args.ClearOptions,
			ValueFormat:  args.ValueFormat,
			Overwrite:    args.Overwrite,
		}

		transform, err := parseTransform(args.Transform)
		if err != nil {
			return err
		}
		m.Transform = transform

		// Each command involves either adding or removing tags, depending on
		// whether Add or Clear is set.
		if args.Add != "" {
			countAddStructTags.Inc()
			m.Add = strings.Split(args.Add, ",")
		} else if args.Clear {
			countRemoveStructTags.Inc()
		}
		if args.AddOptions != "" {
			if options, err := optionsStringToMap(args.AddOptions); err != nil {
				return err
			} else {
				m.AddOptions = options
			}
		}
		if args.Remove != "" {
			m.Remove = strings.Split(args.Remove, ",")
		}
		if args.RemoveOptions != "" {
			if options, err := optionsStringToMap(args.RemoveOptions); err != nil {
				return err
			} else {
				m.RemoveOptions = options
			}
		}
		fh, err := deps.snapshot.ReadFile(ctx, args.URI)
		if err != nil {
			return err
		}
		changes, err := golang.ModifyTags(ctx, deps.snapshot, fh, args, m)
		if err != nil {
			return err
		}
		return applyChanges(ctx, c.s.client, changes)
	})
}

func parseTransform(input string) (modifytags.Transform, error) {
	switch input {
	case "camelcase":
		return modifytags.CamelCase, nil
	case "lispcase":
		return modifytags.LispCase, nil
	case "pascalcase":
		return modifytags.PascalCase, nil
	case "titlecase":
		return modifytags.TitleCase, nil
	case "keep":
		return modifytags.Keep, nil
	case "":
		fallthrough
	case "snakecase":
		return modifytags.SnakeCase, nil
	default:
		return modifytags.SnakeCase, fmt.Errorf("invalid Transform value")
	}
}

func (c *commandHandler) MoveType(ctx context.Context, args command.MoveTypeArgs) error {
	err := c.run(ctx, commandConfig{
		forURI: args.Location.URI,
	}, func(ctx context.Context, deps commandDeps) error {
		changes, err := golang.MoveType(ctx, deps.fh, deps.snapshot, args.Location, "newpkg/new.go")
		if err != nil {
			return err
		}
		return applyChanges(ctx, c.s.client, changes)
	})
	return err
}


================================================
FILE: gopls/internal/server/completion.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"
	"strings"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/completion"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/gopls/internal/work"
	"golang.org/x/tools/internal/event"
)

func (s *server) Completion(ctx context.Context, params *protocol.CompletionParams) (_ *protocol.CompletionList, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("completion")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.Completion", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if params.Range.Start != params.Range.End {
		return nil, fmt.Errorf("textDocument/completion request only applicable for position")
	}
	pos := params.Range.Start

	var candidates []completion.CompletionItem
	var surrounding *completion.Selection
	switch snapshot.FileKind(fh) {
	case file.Go:
		candidates, surrounding, err = completion.Completion(ctx, snapshot, fh, pos, params.Context)
	case file.Mod:
		candidates, surrounding = nil, nil
	case file.Work:
		cl, err := work.Completion(ctx, snapshot, fh, pos)
		if err != nil {
			break
		}
		return cl, nil
	case file.Tmpl:
		var cl *protocol.CompletionList
		cl, err = template.Completion(ctx, snapshot, fh, pos, params.Context)
		if err != nil {
			break // use common error handling, candidates==nil
		}
		return cl, nil
	}
	if err != nil {
		event.Error(ctx, "no completions found", err, label.Position.Of(pos))
	}
	if candidates == nil || surrounding == nil {
		complEmpty.Inc()
		return &protocol.CompletionList{
			IsIncomplete: true,
			Items:        []protocol.CompletionItem{},
		}, nil
	}

	// When using deep completions/fuzzy matching, report results as incomplete so
	// client fetches updated completions after every key stroke.
	options := snapshot.Options()
	incompleteResults := options.DeepCompletion || options.Matcher == settings.Fuzzy

	items, err := toProtocolCompletionItems(candidates, surrounding, options)
	if err != nil {
		return nil, err
	}
	if snapshot.FileKind(fh) == file.Go {
		s.saveLastCompletion(fh.URI(), fh.Version(), items, params.Position)
	}

	if len(items) > 10 {
		// TODO(pjw): long completions are ok for field lists
		complLong.Inc()
	} else {
		complShort.Inc()
	}
	return &protocol.CompletionList{
		IsIncomplete: incompleteResults,
		Items:        items,
	}, nil
}

func (s *server) saveLastCompletion(uri protocol.DocumentURI, version int32, items []protocol.CompletionItem, pos protocol.Position) {
	s.efficacyMu.Lock()
	defer s.efficacyMu.Unlock()
	s.efficacyVersion = version
	s.efficacyURI = uri
	s.efficacyPos = pos
	s.efficacyItems = items
}

// toProtocolCompletionItems converts the candidates to the protocol completion items,
// the candidates must be sorted based on score as it will be respected by client side.
func toProtocolCompletionItems(candidates []completion.CompletionItem, surrounding *completion.Selection, options *settings.Options) ([]protocol.CompletionItem, error) {
	replaceRng, err := surrounding.Range()
	if err != nil {
		return nil, err
	}
	insertRng0, err := surrounding.PrefixRange()
	if err != nil {
		return nil, err
	}
	suffix := surrounding.Suffix()

	var (
		items                  = make([]protocol.CompletionItem, 0, len(candidates))
		numDeepCompletionsSeen int
	)
	for i, candidate := range candidates {
		// Limit the number of deep completions to not overwhelm the user in cases
		// with dozens of deep completion matches.
		if candidate.Depth > 0 {
			if !options.DeepCompletion {
				continue
			}
			if numDeepCompletionsSeen >= completion.MaxDeepCompletions {
				continue
			}
			numDeepCompletionsSeen++
		}
		insertText := candidate.InsertText
		if options.InsertTextFormat == protocol.SnippetTextFormat {
			insertText = candidate.Snippet()
		}

		// This can happen if the client has snippets disabled but the
		// candidate only supports snippet insertion.
		if insertText == "" {
			continue
		}

		var doc *protocol.Or_CompletionItem_documentation
		if candidate.Documentation != "" {
			var value any
			if options.PreferredContentFormat == protocol.Markdown {
				value = protocol.MarkupContent{
					Kind:  protocol.Markdown,
					Value: golang.DocCommentToMarkdown(candidate.Documentation, options),
				}
			} else {
				value = candidate.Documentation
			}
			doc = &protocol.Or_CompletionItem_documentation{Value: value}
		}
		var edits *protocol.Or_CompletionItem_textEdit
		if options.InsertReplaceSupported {
			insertRng := insertRng0
			if suffix == "" || strings.Contains(insertText, suffix) {
				insertRng = replaceRng
			}
			// Insert and Replace ranges share the same start position and
			// the same text edit but the end position may differ.
			// See the comment for the CompletionItem's TextEdit field.
			// https://pkg.go.dev/golang.org/x/tools/gopls/internal/protocol#CompletionItem
			edits = &protocol.Or_CompletionItem_textEdit{
				Value: protocol.InsertReplaceEdit{
					NewText: insertText,
					Insert:  insertRng, // replace up to the cursor position.
					Replace: replaceRng,
				},
			}
		} else {
			edits = &protocol.Or_CompletionItem_textEdit{
				Value: protocol.TextEdit{
					NewText: insertText,
					Range:   replaceRng,
				},
			}
		}
		item := protocol.CompletionItem{
			Label:               candidate.Label,
			Detail:              candidate.Detail,
			Kind:                candidate.Kind,
			TextEdit:            edits,
			InsertTextFormat:    &options.InsertTextFormat,
			AdditionalTextEdits: candidate.AdditionalTextEdits,
			// This is a hack so that the client sorts completion results in the order
			// according to their score. This can be removed upon the resolution of
			// https://github.com/Microsoft/language-server-protocol/issues/348.
			SortText: fmt.Sprintf("%05d", i),

			// Trim operators (VSCode doesn't like weird characters in
			// filterText).
			FilterText: strings.TrimLeft(candidate.InsertText, "&*"),

			Preselect:     i == 0,
			Documentation: doc,
			Tags:          protocol.NonNilSlice(candidate.Tags),
			Deprecated:    candidate.Deprecated,
		}
		items = append(items, item)
	}
	return items, nil
}


================================================
FILE: gopls/internal/server/counters.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import "golang.org/x/telemetry/counter"

// Proposed counters for evaluating gopls code completion.
var (
	complEmpty = counter.New("gopls/completion/len:0")    // count empty suggestions
	complShort = counter.New("gopls/completion/len:<=10") // not empty, not long
	complLong  = counter.New("gopls/completion/len:>10")  // returning more than 10 items

	changeFull  = counter.New("gopls/completion/used:unknown") // full file change in didChange
	complUnused = counter.New("gopls/completion/used:no")      // did not use a completion
	complUsed   = counter.New("gopls/completion/used:yes")     // used a completion

	// exported so tests can verify that counters are incremented
	CompletionCounters = []*counter.Counter{
		complEmpty,
		complShort,
		complLong,
		changeFull,
		complUnused,
		complUsed,
	}
)

// Proposed counters for evaluating gopls change signature and rename. These
// counters increment when the user attempts to perform one of these operations,
// regardless of whether it succeeds.
var (
	countChangeSignature = counter.New("gopls/changesig")

	countRename = counter.New("gopls/rename")
)

// Proposed counters for evaluating gopls refactoring codeactions add struct
// tags and remove struct tags.
var (
	countAddStructTags = counter.New("gopls/structtags:add")

	countRemoveStructTags = counter.New("gopls/structtags:remove")
)

// Proposed counters to evaluate vulncheck_prompt usage patterns.
var (
	// Vulncheck prompt user choices.
	countVulncheckPromptYes    = counter.New("gopls/vulncheck-prompt/choice:yes")
	countVulncheckPromptNo     = counter.New("gopls/vulncheck-prompt/choice:no")
	countVulncheckPromptAlways = counter.New("gopls/vulncheck-prompt/choice:always")
	countVulncheckPromptNever  = counter.New("gopls/vulncheck-prompt/choice:never")

	// Vulncheck prompt upgrade choice.
	countVulncheckUpgradeAll    = counter.New("gopls/vulncheck-prompt/upgrade:yes")
	countVulncheckUpgradeIgnore = counter.New("gopls/vulncheck-prompt/upgrade:no")
)


================================================
FILE: gopls/internal/server/debug.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

// assert panics with the given msg if cond is not true.
func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}


================================================
FILE: gopls/internal/server/definition.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/goasm"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/internal/event"
)

func (s *server) Definition(ctx context.Context, params *protocol.DefinitionParams) (_ []protocol.Location, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("definition")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.Definition", label.URI.Of(params.TextDocument.URI))
	defer done()

	// TODO(rfindley): definition requests should be multiplexed across all views.
	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch kind := snapshot.FileKind(fh); kind {
	case file.Tmpl:
		return template.Definition(snapshot, fh, params.Range)
	case file.Go:
		return golang.Definition(ctx, snapshot, fh, params.Range)
	case file.Asm:
		return goasm.Definition(ctx, snapshot, fh, params.Range)
	default:
		return nil, fmt.Errorf("can't find definitions for file type %s", kind)
	}
}

func (s *server) TypeDefinition(ctx context.Context, params *protocol.TypeDefinitionParams) ([]protocol.Location, error) {
	ctx, done := event.Start(ctx, "server.TypeDefinition", label.URI.Of(params.TextDocument.URI))
	defer done()

	// TODO(rfindley): type definition requests should be multiplexed across all views.
	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}

	defer release()
	switch kind := snapshot.FileKind(fh); kind {
	case file.Go:
		return golang.TypeDefinition(ctx, snapshot, fh, params.Range)
	default:
		return nil, fmt.Errorf("can't find type definitions for file type %s", kind)
	}
}


================================================
FILE: gopls/internal/server/diagnostics.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"runtime"
	"slices"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/work"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/jsonrpc2"
)

// Diagnostic implements the textDocument/diagnostic LSP request, reporting
// diagnostics for the given file.
//
// This is a work in progress.
// TODO(rfindley):
//   - support RelatedDocuments? If so, how? Maybe include other package diagnostics?
//   - support resultID (=snapshot ID)
//   - support multiple views
//   - add orphaned file diagnostics
//   - support go.mod, go.work files
func (s *server) Diagnostic(ctx context.Context, params *protocol.DocumentDiagnosticParams) (*protocol.DocumentDiagnosticReport, error) {
	ctx, done := event.Start(ctx, "server.Diagnostic")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	jsonrpc2.Async(ctx) // allow asynchronous collection of diagnostics

	uri := fh.URI()
	kind := snapshot.FileKind(fh)
	var diagnostics []*cache.Diagnostic
	switch kind {
	case file.Go:
		diagnostics, err = golang.DiagnoseFile(ctx, snapshot, uri)
		if err != nil {
			return nil, err
		}
	default:
		return nil, fmt.Errorf("pull diagnostics not supported for this file kind")
	}
	return &protocol.DocumentDiagnosticReport{
		Value: protocol.RelatedFullDocumentDiagnosticReport{
			FullDocumentDiagnosticReport: protocol.FullDocumentDiagnosticReport{
				Items: cache.ToProtocolDiagnostics(diagnostics...),
			},
		},
	}, nil
}

// fileDiagnostics holds the current state of published diagnostics for a file.
type fileDiagnostics struct {
	publishedHash file.Hash // hash of the last set of diagnostics published for this URI
	mustPublish   bool      // if set, publish diagnostics even if they haven't changed

	// Orphaned file diagnostics are not necessarily associated with any *View
	// (since they are orphaned). Instead, keep track of the modification ID at
	// which they were orphaned (see server.lastModificationID).
	orphanedAt              uint64 // modification ID at which this file was orphaned.
	orphanedFileDiagnostics []*cache.Diagnostic

	// Files may have their diagnostics computed by multiple views, and so
	// diagnostics are organized by View. See the documentation for update for more
	// details about how the set of file diagnostics evolves over time.
	byView map[*cache.View]viewDiagnostics
}

// viewDiagnostics holds a set of file diagnostics computed from a given View.
type viewDiagnostics struct {
	snapshot    uint64 // snapshot sequence ID
	version     int32  // file version
	diagnostics []*cache.Diagnostic
}

// common types; for brevity
type (
	viewSet = map[*cache.View]unit
	diagMap = map[protocol.DocumentURI][]*cache.Diagnostic
)

func sortDiagnostics(d []*cache.Diagnostic) {
	sort.Slice(d, func(i int, j int) bool {
		a, b := d[i], d[j]
		if r := protocol.CompareRange(a.Range, b.Range); r != 0 {
			return r < 0
		}
		if a.Source != b.Source {
			return a.Source < b.Source
		}
		return a.Message < b.Message
	})
}

func (s *server) diagnoseChangedViews(ctx context.Context, modID uint64, lastChange map[*cache.View][]protocol.DocumentURI, cause ModificationSource) {
	// Collect views needing diagnosis.
	s.modificationMu.Lock()
	needsDiagnosis := moremaps.KeySlice(s.viewsToDiagnose)
	s.modificationMu.Unlock()

	// Diagnose views concurrently.
	var wg sync.WaitGroup
	for _, v := range needsDiagnosis {
		snapshot, release, err := v.Snapshot()
		if err != nil {
			s.modificationMu.Lock()
			// The View is shut down. Unlike below, no need to check
			// s.needsDiagnosis[v], since the view can never be diagnosed.
			delete(s.viewsToDiagnose, v)
			s.modificationMu.Unlock()
			continue
		}

		// Collect uris for fast diagnosis. We only care about the most recent
		// change here, because this is just an optimization for the case where the
		// user is actively editing a single file.
		uris := lastChange[v]
		if snapshot.Options().DiagnosticsTrigger == settings.DiagnosticsOnSave && cause == FromDidChange {
			// The user requested to update the diagnostics only on save.
			// Do not diagnose yet.
			release()
			continue
		}

		wg.Add(1)
		go func(snapshot *cache.Snapshot, uris []protocol.DocumentURI) {
			defer release()
			defer wg.Done()
			s.diagnoseSnapshot(ctx, snapshot, uris, snapshot.Options().DiagnosticsDelay)
			s.modificationMu.Lock()

			// Only remove v from s.viewsToDiagnose if the context is not cancelled.
			// This ensures that the snapshot was not cloned before its state was
			// fully evaluated, and therefore avoids missing a change that was
			// irrelevant to an incomplete snapshot.
			//
			// See the documentation for s.viewsToDiagnose for details.
			if ctx.Err() == nil && s.viewsToDiagnose[v] <= modID {
				delete(s.viewsToDiagnose, v)
			}
			s.modificationMu.Unlock()
		}(snapshot, uris)
	}

	wg.Wait()

	// Diagnose orphaned files for the session.
	orphanedFileDiagnostics, err := s.session.OrphanedFileDiagnostics(ctx)
	if err == nil {
		err = s.updateOrphanedFileDiagnostics(ctx, modID, orphanedFileDiagnostics)
	}
	if err != nil {
		if ctx.Err() == nil {
			event.Error(ctx, "warning: while diagnosing orphaned files", err)
		}
	}
}

// diagnoseSnapshot computes and publishes diagnostics for the given snapshot.
//
// If delay is non-zero, computing diagnostics does not start until after this
// delay has expired, to allow work to be cancelled by subsequent changes.
//
// If changedURIs is non-empty, it is a set of recently changed files that
// should be diagnosed immediately, and onDisk reports whether these file
// changes came from a change to on-disk files.
//
// If the provided context is cancelled, diagnostics may be partially
// published. Therefore, the provided context should only be cancelled if there
// will be a subsequent operation to make diagnostics consistent. In general,
// if an operation creates a new snapshot, it is responsible for ensuring that
// snapshot (or a subsequent snapshot in the same View) is eventually
// diagnosed.
func (s *server) diagnoseSnapshot(ctx context.Context, snapshot *cache.Snapshot, changedURIs []protocol.DocumentURI, delay time.Duration) {
	ctx, done := event.Start(ctx, "server.diagnoseSnapshot", snapshot.Labels()...)
	defer done()

	if delay > 0 {
		// 2-phase diagnostics.
		//
		// The first phase just parses and type-checks (but
		// does not analyze) packages directly affected by
		// file modifications.
		//
		// The second phase runs after the delay, and does everything.

		if len(changedURIs) > 0 {
			diagnostics, err := diagnoseChangedFiles(ctx, snapshot, changedURIs)
			if err != nil {
				if ctx.Err() == nil {
					event.Error(ctx, "warning: while diagnosing changed files", err, snapshot.Labels()...)
				}
				return
			}
			s.updateDiagnostics(ctx, snapshot, diagnostics, false)
		}

		select {
		case <-time.After(delay):
		case <-ctx.Done():
			return
		}
	}

	diagnostics, err := s.diagnose(ctx, snapshot)
	if err != nil {
		if ctx.Err() == nil {
			event.Error(ctx, "warning: while diagnosing snapshot", err, snapshot.Labels()...)
		}
		return
	}
	s.updateDiagnostics(ctx, snapshot, diagnostics, true)
}

func diagnoseChangedFiles(ctx context.Context, snapshot *cache.Snapshot, uris []protocol.DocumentURI) (diagMap, error) {
	ctx, done := event.Start(ctx, "server.diagnoseChangedFiles", snapshot.Labels()...)
	defer done()

	toDiagnose := make(map[metadata.PackageID]*metadata.Package)
	for _, uri := range uris {
		// If the file is not open, don't diagnose its package.
		//
		// We don't care about fast diagnostics for files that are no longer open,
		// because the user isn't looking at them. Also, explicitly requesting a
		// package can lead to "command-line-arguments" packages if the file isn't
		// covered by the current View. By avoiding requesting packages for e.g.
		// unrelated file movement, we can minimize these unnecessary packages.
		if !snapshot.IsOpen(uri) {
			continue
		}
		// If the file is not known to the snapshot (e.g., if it was deleted),
		// don't diagnose it.
		if fh, err := snapshot.ReadFile(ctx, uri); err != nil || fh == nil {
			continue
		}

		// Don't request type-checking for builtin.go: it's not a real package.
		if snapshot.IsBuiltin(uri) {
			continue
		}

		// Don't diagnose files that are ignored by `go list` (e.g. testdata).
		if snapshot.IgnoredFile(uri) {
			continue
		}

		// Find all packages that include this file and diagnose them in parallel.
		meta, err := snapshot.NarrowestMetadataForFile(ctx, uri)
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			// TODO(findleyr): we should probably do something with the error here,
			// but as of now this can fail repeatedly if load fails, so can be too
			// noisy to log (and we'll handle things later in the slow pass).
			continue
		}
		// golang/go#65801: only diagnose changes to workspace packages. Otherwise,
		// diagnostics will be unstable, as the slow-path diagnostics will erase
		// them.
		if snapshot.IsWorkspacePackage(meta.ID) {
			toDiagnose[meta.ID] = meta
		}
	}
	diags, err := snapshot.PackageDiagnostics(ctx, moremaps.KeySlice(toDiagnose)...)
	if err != nil {
		if ctx.Err() == nil {
			event.Error(ctx, "warning: diagnostics failed", err, snapshot.Labels()...)
		}
		return nil, err
	}
	// golang/go#59587: guarantee that we compute type-checking diagnostics
	// for every compiled package file, otherwise diagnostics won't be quickly
	// cleared following a fix.
	for _, meta := range toDiagnose {
		for _, uri := range meta.CompiledGoFiles {
			if _, ok := diags[uri]; !ok {
				diags[uri] = nil
			}
		}
	}
	return diags, nil
}

func (s *server) diagnose(ctx context.Context, snapshot *cache.Snapshot) (diagMap, error) {
	ctx, done := event.Start(ctx, "server.diagnose", snapshot.Labels()...)
	defer done()

	// Wait for a free diagnostics slot.
	// TODO(adonovan): opt: shouldn't it be the analysis implementation's
	// job to de-dup and limit resource consumption? In any case this
	// function spends most its time waiting for awaitLoaded, at
	// least initially.
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case s.diagnosticsSema <- struct{}{}:
	}
	defer func() {
		<-s.diagnosticsSema
	}()

	var (
		diagnosticsMu sync.Mutex
		diagnostics   = make(diagMap)
	)
	// common code for dispatching diagnostics
	store := func(operation string, diagsByFile diagMap, err error) {
		if err != nil {
			if ctx.Err() == nil {
				event.Error(ctx, "warning: while "+operation, err, snapshot.Labels()...)
			}
			return
		}
		diagnosticsMu.Lock()
		defer diagnosticsMu.Unlock()
		for uri, diags := range diagsByFile {
			diagnostics[uri] = append(diagnostics[uri], diags...)
		}
	}

	// Diagnostics below are organized by increasing specificity:
	//  go.work > mod > mod upgrade > mod vuln > package, etc.

	// Diagnose go.work file.
	workReports, workErr := work.Diagnostics(ctx, snapshot)
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	store("diagnosing go.work file", workReports, workErr)

	// Diagnose go.mod file.
	modReports, modErr := mod.ParseDiagnostics(ctx, snapshot)
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	store("diagnosing go.mod file", modReports, modErr)

	// Diagnose go.mod upgrades.
	upgradeReports, upgradeErr := mod.UpgradeDiagnostics(ctx, snapshot)
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	store("diagnosing go.mod upgrades", upgradeReports, upgradeErr)

	// Diagnose vulnerabilities.
	vulnReports, vulnErr := mod.VulnerabilityDiagnostics(ctx, snapshot)
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	store("diagnosing vulnerabilities", vulnReports, vulnErr)

	workspacePkgs, err := snapshot.WorkspaceMetadata(ctx)
	if s.shouldIgnoreError(snapshot, err) {
		return diagnostics, ctx.Err()
	}

	initialErr := snapshot.InitializationError()
	if ctx.Err() != nil {
		// Don't update initialization status if the context is cancelled.
		return nil, ctx.Err()
	}

	if initialErr != nil {
		store("critical error", initialErr.Diagnostics, nil)
	}

	// Show the error as a progress error report so that it appears in the
	// status bar. If a client doesn't support progress reports, the error
	// will still be shown as a ShowMessage. If there is no error, any running
	// error progress reports will be closed.
	statusErr := initialErr
	if len(snapshot.Overlays()) == 0 {
		// Don't report a hanging status message if there are no open files at this
		// snapshot.
		statusErr = nil
	}
	s.updateCriticalErrorStatus(ctx, snapshot, statusErr)

	// Diagnose template (.tmpl) files.
	tmplReports := template.Diagnostics(snapshot)
	// NOTE(rfindley): typeCheckSource is not accurate here.
	// (but this will be gone soon anyway).
	store("diagnosing templates", tmplReports, nil)

	// If there are no workspace packages, there is nothing to diagnose and
	// there are no orphaned files.
	if len(workspacePkgs) == 0 {
		return diagnostics, nil
	}

	var wg sync.WaitGroup // for potentially slow operations below

	// Maybe run go mod tidy (if it has been invalidated).
	//
	// Since go mod tidy can be slow, we run it concurrently to diagnostics.
	wg.Go(func() {
		modTidyReports, err := mod.TidyDiagnostics(ctx, snapshot)
		store("running go mod tidy", modTidyReports, err)
	})

	// Run type checking and go/analysis diagnosis of packages in parallel.
	//
	// For analysis, we use the *widest* package for each open file,
	// for two reasons:
	//
	// - Correctness: some analyzers (e.g. unused{param,func}) depend
	//   on it. If applied to a non-test package for which a
	//   corresponding test package exists, they make assumptions
	//   that are falsified in the test package, for example that
	//   all references to unexported symbols are visible to the
	//   analysis.
	//
	// - Efficiency: it may yield a smaller covering set of
	//   PackageIDs for a given set of files. For example, {x.go,
	//   x_test.go} is covered by the single package x_test using
	//   "widest". (Using "narrowest", it would be covered only by
	//   the pair of packages {x, x_test}, Originally we used all
	//   covering packages, so {x.go} alone would be analyzed
	//   twice.)
	var (
		toDiagnose = make(map[metadata.PackageID]*metadata.Package)
		toAnalyze  = make(map[metadata.PackageID]*metadata.Package)

		// secondary index, used to eliminate narrower packages.
		toAnalyzeWidest = make(map[golang.PackagePath]*metadata.Package)
	)
	for _, mp := range workspacePkgs {
		var hasNonIgnored, hasOpenFile bool
		for _, uri := range mp.CompiledGoFiles {
			if !hasNonIgnored && !snapshot.IgnoredFile(uri) {
				hasNonIgnored = true
			}
			if !hasOpenFile && snapshot.IsOpen(uri) {
				hasOpenFile = true
			}
		}
		if hasNonIgnored {
			toDiagnose[mp.ID] = mp
			if hasOpenFile {
				if prev, ok := toAnalyzeWidest[mp.PkgPath]; ok {
					if len(prev.CompiledGoFiles) >= len(mp.CompiledGoFiles) {
						// Previous entry is not narrower; keep it.
						continue
					}
					// Evict previous (narrower) entry.
					delete(toAnalyze, prev.ID)
				}
				toAnalyze[mp.ID] = mp
				toAnalyzeWidest[mp.PkgPath] = mp
			}
		}
	}

	wg.Go(func() {
		compilerOptDetailsDiags, err := s.compilerOptDetailsDiagnostics(ctx, snapshot, toDiagnose)
		store("collecting compiler optimization details", compilerOptDetailsDiags, err)
	})

	// Package diagnostics and analysis diagnostics must both be computed and
	// merged before they can be reported.
	var pkgDiags, analysisDiags diagMap
	// Collect package diagnostics.
	wg.Go(func() {
		var err error
		pkgDiags, err = snapshot.PackageDiagnostics(ctx, moremaps.KeySlice(toDiagnose)...)
		if err != nil {
			event.Error(ctx, "warning: diagnostics failed", err, snapshot.Labels()...)
		}
	})

	// Get diagnostics from analysis framework.
	// This includes type-error analyzers, which suggest fixes to compiler errors.
	wg.Go(func() {
		var err error
		// TODO(rfindley): here and above, we should avoid using the first result
		// if err is non-nil (though as of today it's OK).
		analysisDiags, err = golang.Analyze(ctx, snapshot, toAnalyze, s.progress)

		// Filter out Hint diagnostics for closed files.
		// VS Code already omits Hint diagnostics in the Problems tab, but other
		// clients do not. This filter makes the visibility of Hints more similar
		// across clients.
		for uri, diags := range analysisDiags {
			if !snapshot.IsOpen(uri) {
				newDiags := slices.DeleteFunc(diags, func(diag *cache.Diagnostic) bool {
					return diag.Severity == protocol.SeverityHint
				})
				if len(newDiags) == 0 {
					delete(analysisDiags, uri)
				} else {
					analysisDiags[uri] = newDiags
				}
			}
		}

		if err != nil {
			event.Error(ctx, "warning: analyzing package", err, append(snapshot.Labels(), label.Package.Of(keys.Join(moremaps.KeySlice(toDiagnose))))...)
			return
		}
	})

	wg.Wait()

	// Merge analysis diagnostics with package diagnostics, and store the
	// resulting analysis diagnostics.
	combinedDiags := make(diagMap)
	for uri, adiags := range analysisDiags {
		tdiags := pkgDiags[uri]
		combinedDiags[uri] = golang.CombineDiagnostics(tdiags, adiags)
	}
	for uri, tdiags := range pkgDiags {
		if _, ok := combinedDiags[uri]; !ok {
			combinedDiags[uri] = tdiags
		}
	}
	store("type checking and analysing", combinedDiags, nil) // error reported above

	return diagnostics, nil
}

func (s *server) compilerOptDetailsDiagnostics(ctx context.Context, snapshot *cache.Snapshot, toDiagnose map[metadata.PackageID]*metadata.Package) (diagMap, error) {
	// Process requested diagnostics about compiler optimization details.
	//
	// TODO(rfindley): This should memoize its results if the package has not changed.
	// Consider that these points, in combination with the note below about
	// races, suggest that compiler optimization details should be tracked on the Snapshot.
	diagnostics := make(diagMap)
	seenDirs := make(map[protocol.DocumentURI]bool)
	for _, mp := range toDiagnose {
		if len(mp.CompiledGoFiles) == 0 {
			continue
		}
		dir := mp.CompiledGoFiles[0].Dir()
		if snapshot.WantCompilerOptDetails(dir) {
			if !seenDirs[dir] {
				seenDirs[dir] = true

				perFileDiags, err := golang.CompilerOptDetails(ctx, snapshot, dir)
				if err != nil {
					event.Error(ctx, "warning: compiler optimization details", err, append(snapshot.Labels(), label.URI.Of(dir))...)
					continue
				}
				for uri, diags := range perFileDiags {
					diagnostics[uri] = append(diagnostics[uri], diags...)
				}
			}
		}
	}
	return diagnostics, nil
}

// mustPublishDiagnostics marks the uri as needing publication, independent of
// whether the published contents have changed.
//
// This can be used for ensuring gopls publishes diagnostics after certain file
// events.
func (s *server) mustPublishDiagnostics(uri protocol.DocumentURI) {
	s.diagnosticsMu.Lock()
	defer s.diagnosticsMu.Unlock()

	if s.diagnostics[uri] == nil {
		s.diagnostics[uri] = new(fileDiagnostics)
	}
	s.diagnostics[uri].mustPublish = true
}

const WorkspaceLoadFailure = "Error loading workspace"

// updateCriticalErrorStatus updates the critical error progress notification
// based on err.
//
// If err is nil, or if there are no open files, it clears any existing error
// progress report.
func (s *server) updateCriticalErrorStatus(ctx context.Context, snapshot *cache.Snapshot, err *cache.InitializationError) {
	s.criticalErrorStatusMu.Lock()
	defer s.criticalErrorStatusMu.Unlock()

	// Remove all newlines so that the error message can be formatted in a
	// status bar.
	var errMsg string
	if err != nil {
		errMsg = strings.ReplaceAll(err.MainError.Error(), "\n", " ")
	}

	if s.criticalErrorStatus == nil {
		if errMsg != "" {
			event.Error(ctx, "errors loading workspace", err.MainError, snapshot.Labels()...)
			s.criticalErrorStatus = s.progress.Start(ctx, WorkspaceLoadFailure, errMsg, nil, nil)
		}
		return
	}

	// If an error is already shown to the user, update it or mark it as
	// resolved.
	if errMsg == "" {
		s.criticalErrorStatus.End(ctx, "Done.")
		s.criticalErrorStatus = nil
	} else {
		s.criticalErrorStatus.Report(ctx, errMsg, 0)
	}
}

// updateDiagnostics records the result of diagnosing a snapshot, and publishes
// any diagnostics that need to be updated on the client.
func (s *server) updateDiagnostics(ctx context.Context, snapshot *cache.Snapshot, diagnostics diagMap, final bool) {
	ctx, done := event.Start(ctx, "server.publishDiagnostics")
	defer done()

	s.diagnosticsMu.Lock()
	defer s.diagnosticsMu.Unlock()

	// Before updating any diagnostics, check that the context (i.e. snapshot
	// background context) is not cancelled.
	//
	// If not, then we know that we haven't started diagnosing the next snapshot,
	// because the previous snapshot is cancelled before the next snapshot is
	// returned from Invalidate.
	//
	// Therefore, even if we publish stale diagnostics here, they should
	// eventually be overwritten with accurate diagnostics.
	//
	// TODO(rfindley): refactor the API to force that snapshots are diagnosed
	// after they are created.
	if ctx.Err() != nil {
		return
	}

	// golang/go#65312: since the set of diagnostics depends on the set of views,
	// we get the views *after* locking diagnosticsMu. This ensures that
	// updateDiagnostics does not incorrectly delete diagnostics that have been
	// set for an existing view that was created between the call to
	// s.session.Views() and updateDiagnostics.
	viewMap := make(viewSet)
	for _, v := range s.session.Views() {
		viewMap[v] = unit{}
	}

	// updateAndPublish updates diagnostics for a file, checking both the latest
	// diagnostics for the current snapshot, as well as reconciling the set of
	// views.
	updateAndPublish := func(uri protocol.DocumentURI, f *fileDiagnostics, diags []*cache.Diagnostic) error {
		current, ok := f.byView[snapshot.View()]
		// Update the stored diagnostics if:
		//  1. we've never seen diagnostics for this view,
		//  2. diagnostics are for an older snapshot, or
		//  3. we're overwriting with final diagnostics
		//
		// In other words, we shouldn't overwrite existing diagnostics for a
		// snapshot with non-final diagnostics. This avoids the race described at
		// https://github.com/golang/go/issues/64765#issuecomment-1890144575.
		if !ok || current.snapshot < snapshot.SequenceID() || (current.snapshot == snapshot.SequenceID() && final) {
			fh, err := snapshot.ReadFile(ctx, uri)
			if err != nil {
				return err
			}
			current = viewDiagnostics{
				snapshot:    snapshot.SequenceID(),
				version:     fh.Version(),
				diagnostics: diags,
			}
			if f.byView == nil {
				f.byView = make(map[*cache.View]viewDiagnostics)
			}
			f.byView[snapshot.View()] = current
		}

		return s.publishFileDiagnosticsLocked(ctx, viewMap, uri, current.version, f)
	}

	seen := make(map[protocol.DocumentURI]bool)
	for uri, diags := range diagnostics {
		f, ok := s.diagnostics[uri]
		if !ok {
			f = new(fileDiagnostics)
			s.diagnostics[uri] = f
		}
		seen[uri] = true
		if err := updateAndPublish(uri, f, diags); err != nil {
			if ctx.Err() != nil {
				return
			} else {
				event.Error(ctx, "updateDiagnostics: failed to deliver diagnostics", err, label.URI.Of(uri))
			}
		}
	}

	// TODO(rfindley): perhaps we should clean up files that have no diagnostics.
	// One could imagine a large operation generating diagnostics for a great
	// number of files, after which gopls has to do more bookkeeping into the
	// future.
	if final {
		for uri, f := range s.diagnostics {
			if !seen[uri] {
				if err := updateAndPublish(uri, f, nil); err != nil {
					if ctx.Err() != nil {
						return
					} else {
						event.Error(ctx, "updateDiagnostics: failed to deliver diagnostics", err, label.URI.Of(uri))
					}
				}
			}
		}
	}
}

// updateOrphanedFileDiagnostics records and publishes orphaned file
// diagnostics as a given modification time.
func (s *server) updateOrphanedFileDiagnostics(ctx context.Context, modID uint64, diagnostics diagMap) error {
	views := s.session.Views()
	viewSet := make(viewSet)
	for _, v := range views {
		viewSet[v] = unit{}
	}

	s.diagnosticsMu.Lock()
	defer s.diagnosticsMu.Unlock()

	for uri, diags := range diagnostics {
		f, ok := s.diagnostics[uri]
		if !ok {
			f = new(fileDiagnostics)
			s.diagnostics[uri] = f
		}
		if f.orphanedAt > modID {
			continue
		}
		f.orphanedAt = modID
		f.orphanedFileDiagnostics = diags
		// TODO(rfindley): the version of this file is potentially inaccurate;
		// nevertheless, it should be eventually consistent, because all
		// modifications are diagnosed.
		fh, err := s.session.ReadFile(ctx, uri)
		if err != nil {
			return err
		}
		if err := s.publishFileDiagnosticsLocked(ctx, viewSet, uri, fh.Version(), f); err != nil {
			return err
		}
	}

	// Clear any stale orphaned file diagnostics.
	for uri, f := range s.diagnostics {
		if f.orphanedAt < modID {
			f.orphanedFileDiagnostics = nil
		}
		fh, err := s.session.ReadFile(ctx, uri)
		if err != nil {
			return err
		}
		if err := s.publishFileDiagnosticsLocked(ctx, viewSet, uri, fh.Version(), f); err != nil {
			return err
		}
	}
	return nil
}

// publishFileDiagnosticsLocked publishes a fileDiagnostics value, while holding s.diagnosticsMu.
//
// If the publication succeeds, it updates f.publishedHash and f.mustPublish.
func (s *server) publishFileDiagnosticsLocked(ctx context.Context, views viewSet, uri protocol.DocumentURI, version int32, f *fileDiagnostics) error {
	// We add a disambiguating suffix (e.g. " [darwin,arm64]") to
	// each diagnostic that doesn't occur in the default view;
	// see golang/go#65496.
	type diagSuffix struct {
		diag   *cache.Diagnostic
		suffix string // "" for default build (or orphans)
	}

	// diagSuffixes records the set of view suffixes for a given diagnostic.
	diagSuffixes := make(map[file.Hash][]diagSuffix)
	add := func(diag *cache.Diagnostic, suffix string) {
		h := diag.Hash()
		diagSuffixes[h] = append(diagSuffixes[h], diagSuffix{diag, suffix})
	}

	// Construct the inverse mapping, from diagnostic (hash) to its suffixes (views).
	for _, diag := range f.orphanedFileDiagnostics {
		add(diag, "")
	}

	var allViews []*cache.View
	for view, viewDiags := range f.byView {
		if _, ok := views[view]; !ok {
			delete(f.byView, view) // view no longer exists
			continue
		}
		if viewDiags.version != version {
			continue // a payload of diagnostics applies to a specific file version
		}
		allViews = append(allViews, view)
	}

	// Only report diagnostics from relevant views for a file. This avoids
	// spurious import errors when a view has only a partial set of dependencies
	// for a package (golang/go#66425).
	//
	// It's ok to use the session to derive the eligible views, because we
	// publish diagnostics following any state change, so the set of relevant
	// views is eventually consistent.
	relevantViews, err := cache.RelevantViews(ctx, s.session, uri, allViews)
	if err != nil {
		return err
	}

	if len(relevantViews) == 0 {
		// If we have no preferred diagnostics for a given file (i.e., the file is
		// not naturally nested within a view), then all diagnostics should be
		// considered valid.
		//
		// This could arise if the user jumps to definition outside the workspace.
		// There is no view that owns the file, so its diagnostics are valid from
		// any view.
		relevantViews = allViews
	}

	for _, view := range relevantViews {
		viewDiags := f.byView[view]
		// Compute the view's suffix (e.g. " [darwin,arm64]").
		var suffix string
		{
			var words []string
			if view.GOOS() != runtime.GOOS {
				words = append(words, view.GOOS())
			}
			if view.GOARCH() != runtime.GOARCH {
				words = append(words, view.GOARCH())
			}
			if len(words) > 0 {
				suffix = fmt.Sprintf(" [%s]", strings.Join(words, ","))
			}
		}

		for _, diag := range viewDiags.diagnostics {
			add(diag, suffix)
		}
	}

	// De-dup diagnostics across views by hash, and sort.
	var (
		hash   file.Hash
		unique []*cache.Diagnostic
	)
	for h, items := range diagSuffixes {
		// Sort the items by ascending suffix, so that the
		// default view (if present) is first.
		// (The others are ordered arbitrarily.)
		sort.Slice(items, func(i, j int) bool {
			return items[i].suffix < items[j].suffix
		})

		// If the diagnostic was not present in
		// the default view, add the view suffix.
		first := items[0]
		if first.suffix != "" {
			diag2 := *first.diag // shallow copy
			diag2.Message += first.suffix
			first.diag = &diag2
			h = diag2.Hash() // update the hash
		}

		hash.XORWith(h)
		unique = append(unique, first.diag)
	}
	sortDiagnostics(unique)

	// Publish, if necessary.
	if hash != f.publishedHash || f.mustPublish {
		if err := s.client.PublishDiagnostics(ctx, &protocol.PublishDiagnosticsParams{
			Diagnostics: cache.ToProtocolDiagnostics(unique...),
			URI:         uri,
			Version:     version, // 0 ("on disk") => omitted from JSON encoding
		}); err != nil {
			return err
		}
		f.publishedHash = hash
		f.mustPublish = false
	}
	return nil
}

func (s *server) shouldIgnoreError(snapshot *cache.Snapshot, err error) bool {
	if err == nil { // if there is no error at all
		return false
	}
	if errors.Is(err, context.Canceled) {
		return true
	}
	// If the folder has no Go code in it, we shouldn't spam the user with a warning.
	// TODO(rfindley): surely it is not correct to walk the folder here just to
	// suppress diagnostics, every time we compute diagnostics.
	var hasGo bool
	_ = filepath.Walk(snapshot.Folder().Path(), func(_ string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if !strings.HasSuffix(info.Name(), ".go") {
			return nil
		}
		hasGo = true
		return errors.New("done")
	})
	return !hasGo
}


================================================
FILE: gopls/internal/server/folding_range.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) FoldingRange(ctx context.Context, params *protocol.FoldingRangeParams) ([]protocol.FoldingRange, error) {
	ctx, done := event.Start(ctx, "server.FoldingRange", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	if snapshot.FileKind(fh) != file.Go {
		return nil, nil // empty result
	}
	return golang.FoldingRange(ctx, snapshot, fh, snapshot.Options().LineFoldingOnly)
}


================================================
FILE: gopls/internal/server/format.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/work"
	"golang.org/x/tools/internal/event"
)

func (s *server) Formatting(ctx context.Context, params *protocol.DocumentFormattingParams) ([]protocol.TextEdit, error) {
	ctx, done := event.Start(ctx, "server.Formatting", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	switch snapshot.FileKind(fh) {
	case file.Mod:
		return mod.Format(ctx, snapshot, fh)
	case file.Go:
		return golang.Format(ctx, snapshot, fh)
	case file.Work:
		return work.Format(ctx, snapshot, fh)
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/general.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

// This file defines server methods related to initialization,
// options, shutdown, and exit.

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"go/build"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strings"
	"sync"

	"golang.org/x/telemetry/counter"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	debuglog "golang.org/x/tools/gopls/internal/debug/log"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/goversion"
	"golang.org/x/tools/gopls/internal/util/moremaps"
	"golang.org/x/tools/gopls/internal/util/moreslices"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
)

func (s *server) Initialize(ctx context.Context, params *protocol.ParamInitialize) (*protocol.InitializeResult, error) {
	ctx, done := event.Start(ctx, "server.Initialize")
	defer done()

	var clientName string
	if params != nil && params.ClientInfo != nil {
		clientName = params.ClientInfo.Name
	}
	recordClientInfo(clientName)

	s.stateMu.Lock()
	if s.state >= serverInitializing {
		defer s.stateMu.Unlock()
		return nil, fmt.Errorf("%w: initialize called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
	}
	s.state = serverInitializing
	s.stateMu.Unlock()

	s.progress.SetSupportsWorkDoneProgress(params.Capabilities.Window.WorkDoneProgress)

	options := s.Options().Clone()
	// TODO(rfindley): eliminate this defer.
	defer func() { s.SetOptions(options) }()

	// Process initialization options.
	{
		res, errs := options.Set(params.InitializationOptions)
		s.handleOptionResult(ctx, res, errs)
	}
	options.ForClientCapabilities(params.ClientInfo, params.Capabilities)

	if options.MaxFileCacheBytes > 0 {
		filecache.SetBudget(options.MaxFileCacheBytes)
	}

	if options.ShowBugReports {
		// Report the next bug that occurs on the server.
		bug.Handle(func(b bug.Bug) {
			msg := &protocol.ShowMessageParams{
				Type:    protocol.Error,
				Message: fmt.Sprintf("A bug occurred on the server: %s\nLocation:%s", b.Description, b.Key),
			}
			go s.eventuallyShowMessage(context.Background(), msg)
		})
	}

	folders := params.WorkspaceFolders
	if len(folders) == 0 {
		if params.RootURI != "" {
			folders = []protocol.WorkspaceFolder{{
				URI:  string(params.RootURI),
				Name: path.Base(params.RootURI.Path()),
			}}
		}
	}
	s.pendingFolders = append(s.pendingFolders, folders...)

	var codeActionProvider any = true
	if ca := params.Capabilities.TextDocument.CodeAction; len(ca.CodeActionLiteralSupport.CodeActionKind.ValueSet) > 0 {
		// If the client has specified CodeActionLiteralSupport,
		// send the code actions we support.
		//
		// Using CodeActionOptions is only valid if codeActionLiteralSupport is set.
		codeActionProvider = &protocol.CodeActionOptions{
			CodeActionKinds: s.getSupportedCodeActions(),
			ResolveProvider: true,
		}
	}

	var diagnosticProvider *protocol.Or_ServerCapabilities_diagnosticProvider
	if options.PullDiagnostics {
		diagnosticProvider = &protocol.Or_ServerCapabilities_diagnosticProvider{
			Value: protocol.DiagnosticOptions{
				InterFileDependencies: true,
				WorkspaceDiagnostics:  false, // we don't support workspace/diagnostic
			},
		}
	}

	var renameOpts any = true
	if r := params.Capabilities.TextDocument.Rename; r != nil && r.PrepareSupport {
		renameOpts = protocol.RenameOptions{
			PrepareProvider: r.PrepareSupport,
		}
	}

	var semanticTokenProvider any
	if options.SemanticTokens {
		semanticTokenProvider = protocol.SemanticTokensOptions{
			Range: &protocol.Or_SemanticTokensOptions_range{Value: true},
			Full:  &protocol.Or_SemanticTokensOptions_full{Value: true},
			Legend: protocol.SemanticTokensLegend{
				TokenTypes:     moreslices.ConvertStrings[string](semtok.Types),
				TokenModifiers: moreslices.ConvertStrings[string](semtok.Modifiers),
			},
		}
	}

	versionInfo := debug.VersionInfo()

	goplsVersion, err := json.Marshal(versionInfo)
	if err != nil {
		return nil, err
	}

	return &protocol.InitializeResult{
		Capabilities: protocol.ServerCapabilities{
			CallHierarchyProvider: &protocol.Or_ServerCapabilities_callHierarchyProvider{Value: true},
			CodeActionProvider:    codeActionProvider,
			CodeLensProvider:      &protocol.CodeLensOptions{}, // must be non-nil to enable the code lens capability
			CompletionProvider: &protocol.CompletionOptions{
				TriggerCharacters: []string{"."},
			},
			DefinitionProvider:         &protocol.Or_ServerCapabilities_definitionProvider{Value: true},
			TypeDefinitionProvider:     &protocol.Or_ServerCapabilities_typeDefinitionProvider{Value: true},
			ImplementationProvider:     &protocol.Or_ServerCapabilities_implementationProvider{Value: true},
			DocumentFormattingProvider: &protocol.Or_ServerCapabilities_documentFormattingProvider{Value: true},
			DocumentSymbolProvider:     &protocol.Or_ServerCapabilities_documentSymbolProvider{Value: true},
			WorkspaceSymbolProvider:    &protocol.Or_ServerCapabilities_workspaceSymbolProvider{Value: true},
			ExecuteCommandProvider: &protocol.ExecuteCommandOptions{
				Commands: protocol.NonNilSlice(options.SupportedCommands),
			},
			FoldingRangeProvider:      &protocol.Or_ServerCapabilities_foldingRangeProvider{Value: true},
			HoverProvider:             &protocol.Or_ServerCapabilities_hoverProvider{Value: true},
			DocumentHighlightProvider: &protocol.Or_ServerCapabilities_documentHighlightProvider{Value: true},
			DocumentLinkProvider:      &protocol.DocumentLinkOptions{},
			InlayHintProvider:         protocol.InlayHintOptions{},
			DiagnosticProvider:        diagnosticProvider,
			ReferencesProvider:        &protocol.Or_ServerCapabilities_referencesProvider{Value: true},
			RenameProvider:            renameOpts,
			SelectionRangeProvider:    &protocol.Or_ServerCapabilities_selectionRangeProvider{Value: true},
			SemanticTokensProvider:    semanticTokenProvider,
			SignatureHelpProvider: &protocol.SignatureHelpOptions{
				TriggerCharacters: []string{"(", ","},
				// Used to update or dismiss signature help when it's already active,
				// typically after a call expression is closed.
				RetriggerCharacters: []string{")"},
			},
			TextDocumentSync: &protocol.TextDocumentSyncOptions{
				Change:    protocol.Incremental,
				OpenClose: true,
				Save: &protocol.SaveOptions{
					IncludeText: false,
				},
			},
			TypeHierarchyProvider: &protocol.Or_ServerCapabilities_typeHierarchyProvider{Value: true},
			Workspace: &protocol.WorkspaceOptions{
				WorkspaceFolders: &protocol.WorkspaceFolders5Gn{
					Supported:           true,
					ChangeNotifications: "workspace/didChangeWorkspaceFolders",
				},
				FileOperations: &protocol.FileOperationOptions{
					DidCreate: &protocol.FileOperationRegistrationOptions{
						Filters: []protocol.FileOperationFilter{{
							Scheme: "file",
							// gopls is only interested with files in .go extension.
							Pattern: protocol.FileOperationPattern{Glob: "**/*.go"},
						}},
					},
				},
			},
			Experimental: map[string]any{
				// interactiveResolveProvider lists the LSP objects that support
				// an interactive resolution stage. For instance, the presence of
				// "command" indicates that the server handles "command/resolve"
				// requests.
				//
				// Due to the existence of "codeAction/resolve" and language
				// clients that resolve code action eagerly, "codeAction" can
				// never be interactively resolved.
				//
				// TODO(hxjiang): experiment with interactively resolving
				// "RenameParams". See golang/go#69107.
				"interactiveResolveProvider": []string{"command"},
			},
		},
		ServerInfo: &protocol.ServerInfo{
			Name:    "gopls",
			Version: string(goplsVersion),
		},
	}, nil
}

func (s *server) Initialized(ctx context.Context, params *protocol.InitializedParams) error {
	ctx, done := event.Start(ctx, "server.Initialized")
	defer done()

	s.stateMu.Lock()
	if s.state >= serverInitialized {
		defer s.stateMu.Unlock()
		return fmt.Errorf("%w: initialized called while server in %v state", jsonrpc2.ErrInvalidRequest, s.state)
	}
	s.state = serverInitialized
	s.stateMu.Unlock()

	for _, not := range s.notifications {
		s.client.ShowMessage(ctx, not) // ignore error
	}
	s.notifications = nil

	s.addFolders(ctx, s.pendingFolders)

	s.pendingFolders = nil
	s.checkViewGoVersions()

	var registrations []protocol.Registration
	options := s.Options()
	if options.ConfigurationSupported && options.DynamicConfigurationSupported {
		registrations = append(registrations, protocol.Registration{
			ID:     "workspace/didChangeConfiguration",
			Method: "workspace/didChangeConfiguration",
		})
	}
	if len(registrations) > 0 {
		if err := s.client.RegisterCapability(ctx, &protocol.RegistrationParams{
			Registrations: registrations,
		}); err != nil {
			return err
		}
	}

	// Ask (maybe) about enabling telemetry. Do this asynchronously, as it's OK
	// for users to ignore or dismiss the question.
	go s.maybePromptForTelemetry(ctx, options.TelemetryPrompt)

	return nil
}

// checkViewGoVersions checks whether any Go version used by a view is too old,
// raising a showMessage notification if so.
//
// It should be called after views change.
func (s *server) checkViewGoVersions() {
	oldestVersion, fromBuild := go1Point(), true
	for _, view := range s.session.Views() {
		viewVersion := view.GoVersion()
		if oldestVersion == -1 || viewVersion < oldestVersion {
			oldestVersion, fromBuild = viewVersion, false
		}
		if viewVersion >= 0 {
			counter.Inc(fmt.Sprintf("gopls/goversion:1.%d", viewVersion))
		}
	}

	if msg, isError := goversion.Message(oldestVersion, fromBuild); msg != "" {
		mType := protocol.Warning
		if isError {
			mType = protocol.Error
		}
		s.eventuallyShowMessage(context.Background(), &protocol.ShowMessageParams{
			Type:    mType,
			Message: msg,
		})
	}
}

// go1Point returns the x in Go 1.x. If an error occurs extracting the go
// version, it returns -1.
//
// Copied from the testenv package.
func go1Point() int {
	for i := len(build.Default.ReleaseTags) - 1; i >= 0; i-- {
		var version int
		if _, err := fmt.Sscanf(build.Default.ReleaseTags[i], "go1.%d", &version); err != nil {
			continue
		}
		return version
	}
	return -1
}

// addFolders adds the specified list of "folders" (that's Windows for
// directories) to the session. It does not return an error, though it
// may report an error to the client over LSP if one or more folders
// had problems, for example, folders with unsupported file system.
func (s *server) addFolders(ctx context.Context, folders []protocol.WorkspaceFolder) {
	originalViews := len(s.session.Views())
	viewErrors := make(map[protocol.URI]error)

	// Skip non-'file' scheme, or invalid workspace folders,
	// and log them form error reports.
	// VS Code's file system API
	// (https://code.visualstudio.com/api/references/vscode-api#FileSystem)
	// allows extension to define their own schemes and register
	// them with the workspace. We've seen gitlens://, decompileFs://, etc
	// but the list can grow over time.
	var filtered []protocol.WorkspaceFolder
	for _, f := range folders {
		uri, err := protocol.ParseDocumentURI(f.URI)
		if err != nil {
			debuglog.Warning.Logf(ctx, "skip adding virtual folder %q - invalid folder URI: %v", f.Name, err)
			continue
		}
		if s.session.HasView(uri) {
			debuglog.Warning.Logf(ctx, "skip adding the already added folder %q - its view has been created before", f.Name)
			continue
		}
		filtered = append(filtered, f)
	}
	folders = filtered

	var ndiagnose sync.WaitGroup // number of unfinished diagnose calls
	if s.Options().VerboseWorkDoneProgress {
		work := s.progress.Start(ctx, DiagnosticWorkTitle(FromInitialWorkspaceLoad), "Calculating diagnostics for initial workspace load...", nil, nil)
		defer func() {
			go func() {
				ndiagnose.Wait()
				work.End(ctx, "Done.")
			}()
		}()
	}
	// Only one view gets to have a workspace.
	var nsnapshots sync.WaitGroup // number of unfinished snapshot initializations
	for _, folder := range folders {
		uri, err := protocol.ParseDocumentURI(folder.URI)
		if err != nil {
			viewErrors[folder.URI] = fmt.Errorf("invalid folder URI: %v", err)
			continue
		}
		work := s.progress.Start(ctx, "Setting up workspace", "Loading packages...", nil, nil)
		snapshot, release, err := s.addView(ctx, folder.Name, uri)
		if err != nil {
			if err == cache.ErrViewExists {
				continue
			}
			viewErrors[folder.URI] = err
			work.End(ctx, fmt.Sprintf("Error loading packages: %s", err))
			continue
		}
		// Inv: release() must be called once.

		// Initialize snapshot asynchronously.
		initialized := make(chan struct{})
		nsnapshots.Add(1)
		go func() {
			snapshot.AwaitInitialized(ctx)
			work.End(ctx, "Finished loading packages.")
			nsnapshots.Done()
			close(initialized) // signal
		}()

		// Diagnose the newly created view asynchronously.
		ndiagnose.Go(func() {
			s.diagnoseSnapshot(snapshot.BackgroundContext(), snapshot, nil, 0)
			<-initialized
			release()
		})
	}

	// Wait for snapshots to be initialized so that all files are known.
	// (We don't need to wait for diagnosis to finish.)
	nsnapshots.Wait()

	// Register for file watching notifications, if they are supported.
	if err := s.updateWatchedDirectories(ctx); err != nil {
		event.Error(ctx, "failed to register for file watching notifications", err)
	}

	// Report any errors using the protocol.
	if len(viewErrors) > 0 {
		var errMsg strings.Builder
		fmt.Fprintf(&errMsg, "Error loading workspace folders (expected %v, got %v)\n", len(folders), len(s.session.Views())-originalViews)
		for uri, err := range viewErrors {
			fmt.Fprintf(&errMsg, "failed to load view for %s: %v\n", uri, err)
		}
		showMessage(ctx, s.client, protocol.Error, errMsg.String())
	}
}

// updateWatchedDirectories compares the current set of directories to watch
// with the previously registered set of directories. If the set of directories
// has changed, we unregister and re-register for file watching notifications.
// updatedSnapshots is the set of snapshots that have been updated.
func (s *server) updateWatchedDirectories(ctx context.Context) error {
	patterns := s.session.FileWatchingGlobPatterns(ctx)

	s.watchedGlobPatternsMu.Lock()
	defer s.watchedGlobPatternsMu.Unlock()

	// Nothing to do if the set of workspace directories is unchanged.
	if moremaps.SameKeys(s.watchedGlobPatterns, patterns) {
		return nil
	}

	// If the set of directories to watch has changed, register the updates and
	// unregister the previously watched directories. This ordering avoids a
	// period where no files are being watched. Still, if a user makes on-disk
	// changes before these updates are complete, we may miss them for the new
	// directories.
	prevID := s.watchRegistrationCount - 1
	if err := s.registerWatchedDirectoriesLocked(ctx, patterns); err != nil {
		return err
	}
	if prevID >= 0 {
		return s.client.UnregisterCapability(ctx, &protocol.UnregistrationParams{
			Unregisterations: []protocol.Unregistration{{
				ID:     watchedFilesCapabilityID(prevID),
				Method: "workspace/didChangeWatchedFiles",
			}},
		})
	}
	return nil
}

func watchedFilesCapabilityID(id int) string {
	return fmt.Sprintf("workspace/didChangeWatchedFiles-%d", id)
}

// registerWatchedDirectoriesLocked sends the workspace/didChangeWatchedFiles
// registrations to the client and updates s.watchedDirectories.
// The caller must not subsequently mutate patterns.
func (s *server) registerWatchedDirectoriesLocked(ctx context.Context, patterns map[protocol.RelativePattern]unit) error {
	if !s.Options().DynamicWatchedFilesSupported {
		return nil
	}

	supportsRelativePatterns := s.Options().RelativePatternsSupported

	s.watchedGlobPatterns = patterns
	watchers := make([]protocol.FileSystemWatcher, 0, len(patterns)) // must be a slice
	val := protocol.WatchChange | protocol.WatchDelete | protocol.WatchCreate
	for pattern := range patterns {
		var value any
		if supportsRelativePatterns && pattern.BaseURI != "" {
			value = pattern
		} else {
			p := pattern.Pattern
			if pattern.BaseURI != "" {
				p = path.Join(filepath.ToSlash(pattern.BaseURI.Path()), p)
			}
			value = p
		}
		watchers = append(watchers, protocol.FileSystemWatcher{
			GlobPattern: protocol.GlobPattern{Value: value},
			Kind:        &val,
		})
	}

	if err := s.client.RegisterCapability(ctx, &protocol.RegistrationParams{
		Registrations: []protocol.Registration{{
			ID:     watchedFilesCapabilityID(s.watchRegistrationCount),
			Method: "workspace/didChangeWatchedFiles",
			RegisterOptions: protocol.DidChangeWatchedFilesRegistrationOptions{
				Watchers: watchers,
			},
		}},
	}); err != nil {
		return err
	}
	s.watchRegistrationCount++
	return nil
}

// Options returns the current server options.
//
// The caller must not modify the result.
func (s *server) Options() *settings.Options {
	s.optionsMu.Lock()
	defer s.optionsMu.Unlock()
	return s.options
}

// SetOptions sets the current server options.
//
// The caller must not subsequently modify the options.
func (s *server) SetOptions(opts *settings.Options) {
	s.optionsMu.Lock()
	defer s.optionsMu.Unlock()
	s.options = opts
}

func (s *server) newFolder(ctx context.Context, folder protocol.DocumentURI, name string, opts *settings.Options) (*cache.Folder, error) {
	env, err := cache.FetchGoEnv(ctx, folder, opts)
	if err != nil {
		return nil, err
	}

	// Increment folder counters.
	switch {
	case env.GOTOOLCHAIN == "auto" || strings.Contains(env.GOTOOLCHAIN, "+auto"):
		counter.Inc("gopls/gotoolchain:auto")
	case env.GOTOOLCHAIN == "path" || strings.Contains(env.GOTOOLCHAIN, "+path"):
		counter.Inc("gopls/gotoolchain:path")
	case env.GOTOOLCHAIN == "local": // local+auto and local+path handled above
		counter.Inc("gopls/gotoolchain:local")
	default:
		counter.Inc("gopls/gotoolchain:other")
	}

	// Record whether a driver is in use so that it appears in the
	// user's telemetry upload. Although we can't correlate the
	// driver information with the crash or bug.Report at the
	// granularity of the process instance, users that use a
	// driver tend to do so most of the time, so we'll get a
	// strong clue. See #60890 for an example of an issue where
	// this information would have been helpful.
	if env.EffectiveGOPACKAGESDRIVER != "" {
		counter.Inc("gopls/gopackagesdriver")
	}

	return &cache.Folder{
		Dir:     folder,
		Name:    name,
		Options: opts,
		Env:     *env,
	}, nil
}

// fetchFolderOptions makes a workspace/configuration request for the given
// folder, and populates options with the result.
//
// If folder is "", fetchFolderOptions makes an unscoped request.
func (s *server) fetchFolderOptions(ctx context.Context, folder protocol.DocumentURI) (*settings.Options, error) {
	opts := s.Options()
	if !opts.ConfigurationSupported {
		return opts, nil
	}
	var scopeURI *string
	if folder != "" {
		scope := string(folder)
		scopeURI = &scope
	}
	configs, err := s.client.Configuration(ctx, &protocol.ParamConfiguration{
		Items: []protocol.ConfigurationItem{{
			ScopeURI: scopeURI,
			Section:  "gopls",
		}},
	},
	)
	if err != nil {
		return nil, fmt.Errorf("failed to get workspace configuration from client (%s): %v", folder, err)
	}

	opts = opts.Clone()
	for _, config := range configs {
		res, errs := opts.Set(config)
		s.handleOptionResult(ctx, res, errs)
	}
	return opts, nil
}

func (s *server) eventuallyShowMessage(ctx context.Context, msg *protocol.ShowMessageParams) {
	s.stateMu.Lock()
	defer s.stateMu.Unlock()
	if s.state == serverInitialized {
		_ = s.client.ShowMessage(ctx, msg) // ignore error
	}
	s.notifications = append(s.notifications, msg)
}

func (s *server) handleOptionResult(ctx context.Context, applied []telemetry.CounterPath, optionErrors []error) {
	for _, path := range applied {
		path = append(settings.CounterPath{"gopls", "setting"}, path...)
		counter.Inc(path.FullName())
	}

	var warnings, errs []string
	for _, err := range optionErrors {
		if err == nil {
			panic("nil error passed to handleOptionErrors")
		}
		if errors.Is(err, new(settings.SoftError)) {
			warnings = append(warnings, err.Error())
		} else {
			errs = append(errs, err.Error())
		}
	}

	// Sort messages, but put errors first.
	//
	// Having stable content for the message allows clients to de-duplicate. This
	// matters because we may send duplicate warnings for clients that support
	// dynamic configuration: one for the initial settings, and then more for the
	// individual viewsettings.
	var msgs []string
	msgType := protocol.Warning
	if len(errs) > 0 {
		msgType = protocol.Error
		sort.Strings(errs)
		msgs = append(msgs, errs...)
	}
	if len(warnings) > 0 {
		sort.Strings(warnings)
		msgs = append(msgs, warnings...)
	}

	if len(msgs) > 0 {
		// Settings
		combined := "Invalid settings: " + strings.Join(msgs, "; ")
		params := &protocol.ShowMessageParams{
			Type:    msgType,
			Message: combined,
		}
		s.eventuallyShowMessage(ctx, params)
	}
}

// Shutdown implements the 'shutdown' LSP handler. It releases resources
// associated with the server and waits for all ongoing work to complete.
func (s *server) Shutdown(ctx context.Context) error {
	ctx, done := event.Start(ctx, "server.Shutdown")
	defer done()

	s.stateMu.Lock()
	defer s.stateMu.Unlock()
	if s.state < serverInitialized {
		event.Log(ctx, "server shutdown without initialization")
	}
	if s.state != serverShutDown {
		// Wait for the webserver (if any) to finish.
		if s.web != nil {
			s.web.server.Shutdown(ctx) // ignore error
		}

		// drop all the active views
		s.session.Shutdown(ctx)
		s.state = serverShutDown
	}
	return nil
}

func (s *server) Exit(ctx context.Context) error {
	ctx, done := event.Start(ctx, "server.Exit")
	defer done()

	s.stateMu.Lock()
	defer s.stateMu.Unlock()

	s.client.Close() // ignore error

	if s.state != serverShutDown {
		// TODO: We should be able to do better than this.
		os.Exit(1)
	}
	// We don't terminate the process on a normal exit, we just allow it to
	// close naturally if needed after the connection is closed.
	return nil
}

// recordClientInfo records gopls client info.
func recordClientInfo(clientName string) {
	key := "gopls/client:other"
	switch clientName {
	case "Visual Studio Code":
		key = "gopls/client:vscode"
	case "Visual Studio Code - Insiders":
		key = "gopls/client:vscode-insiders"
	case "VSCodium":
		key = "gopls/client:vscodium"
	case "code-server":
		// https://github.com/coder/code-server/blob/3cb92edc76ecc2cfa5809205897d93d4379b16a6/ci/build/build-vscode.sh#L19
		key = "gopls/client:code-server"
	case "Eglot":
		// https://lists.gnu.org/archive/html/bug-gnu-emacs/2023-03/msg00954.html
		key = "gopls/client:eglot"
	case "govim":
		// https://github.com/govim/govim/pull/1189
		key = "gopls/client:govim"
	case "helix":
		// https://github.com/helix-editor/helix/blob/d0218f7e78bc0c3af4b0995ab8bda66b9c542cf3/helix-lsp/src/client.rs#L714
		key = "gopls/client:helix"
	case "Neovim":
		// https://github.com/neovim/neovim/blob/42333ea98dfcd2994ee128a3467dfe68205154cd/runtime/lua/vim/lsp.lua#L1361
		key = "gopls/client:neovim"
	case "coc.nvim":
		// https://github.com/neoclide/coc.nvim/blob/3dc6153a85ed0f185abec1deb972a66af3fbbfb4/src/language-client/client.ts#L994
		key = "gopls/client:coc.nvim"
	case "Sublime Text LSP":
		// https://github.com/sublimelsp/LSP/blob/e608f878e7e9dd34aabe4ff0462540fadcd88fcc/plugin/core/sessions.py#L493
		key = "gopls/client:sublimetext"
	case "Windsurf":
		key = "gopls/client:windsurf"
	case "Cursor":
		key = "gopls/client:cursor"
	case "Zed", "Zed Dev", "Zed Nightly", "Zed Preview":
		// https: //github.com/zed-industries/zed/blob/0ac17526687bf11007f0fbb5c3b2ff463ce47293/crates/release_channel/src/lib.rs#L147
		key = "gopls/client:zed"
	default:
		// Accumulate at least a local counter for an unknown
		// client name, but also fall through to count it as
		// ":other" for collection.
		if clientName != "" {
			counter.New(fmt.Sprintf("gopls/client-other:%s", clientName)).Inc()
		}
	}
	counter.Inc(key)
}


================================================
FILE: gopls/internal/server/highlight.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/internal/event"
)

func (s *server) DocumentHighlight(ctx context.Context, params *protocol.DocumentHighlightParams) ([]protocol.DocumentHighlight, error) {
	ctx, done := event.Start(ctx, "server.DocumentHighlight", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	switch snapshot.FileKind(fh) {
	case file.Tmpl:
		return template.Highlight(ctx, snapshot, fh, params.Range)
	case file.Go:
		rngs, err := golang.Highlight(ctx, snapshot, fh, params.Range)
		if err != nil {
			event.Error(ctx, "no highlight", err)
		}
		return rngs, nil
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/hover.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/gopls/internal/work"
	"golang.org/x/tools/internal/event"
)

func (s *server) Hover(ctx context.Context, params *protocol.HoverParams) (_ *protocol.Hover, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("hover")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.Hover", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	switch snapshot.FileKind(fh) {
	case file.Mod:
		return mod.Hover(ctx, snapshot, fh, params.Range)
	case file.Go:
		var pkgURL func(path golang.PackagePath, fragment string) protocol.URI
		if snapshot.Options().LinksInHover == settings.LinksInHover_Gopls {
			web, err := s.getWeb()
			if err != nil {
				event.Error(ctx, "failed to start web server", err)
			} else {
				pkgURL = func(path golang.PackagePath, fragment string) protocol.URI {
					return web.PkgURL(snapshot.View().ID(), path, fragment)
				}
			}
		}
		return golang.Hover(ctx, snapshot, fh, params.Range, pkgURL)
	case file.Tmpl:
		return template.Hover(ctx, snapshot, fh, params.Range)
	case file.Work:
		return work.Hover(ctx, snapshot, fh, params.Range)
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/implementation.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/internal/event"
)

func (s *server) Implementation(ctx context.Context, params *protocol.ImplementationParams) (_ []protocol.Location, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("implementation")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.Implementation", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	if snapshot.FileKind(fh) != file.Go {
		return nil, nil // empty result
	}
	return golang.Implementation(ctx, snapshot, fh, params.Range)
}


================================================
FILE: gopls/internal/server/inlay_hint.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) InlayHint(ctx context.Context, params *protocol.InlayHintParams) ([]protocol.InlayHint, error) {
	ctx, done := event.Start(ctx, "server.InlayHint", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	switch snapshot.FileKind(fh) {
	case file.Mod:
		return mod.InlayHint(ctx, snapshot, fh, params.Range)
	case file.Go:
		return golang.InlayHint(ctx, snapshot, fh, params.Range)
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/link.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/token"
	"net/url"
	"path/filepath"
	"regexp"
	"strings"
	"sync"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/module"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/event"
	"mvdan.cc/xurls/v2"
)

func (s *server) DocumentLink(ctx context.Context, params *protocol.DocumentLinkParams) (links []protocol.DocumentLink, err error) {
	ctx, done := event.Start(ctx, "server.DocumentLink")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	switch snapshot.FileKind(fh) {
	case file.Mod:
		links, err = modLinks(ctx, snapshot, fh)
	case file.Go:
		links, err = goLinks(ctx, snapshot, fh)
	}
	// Don't return errors for document links.
	if err != nil {
		event.Error(ctx, "failed to compute document links", err, label.URI.Of(fh.URI()))
		return nil, nil // empty result
	}
	return links, nil // may be empty (for other file types)
}

func modLinks(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.DocumentLink, error) {
	pm, err := snapshot.ParseMod(ctx, fh)
	if err != nil {
		return nil, err
	}

	var links []protocol.DocumentLink
	for _, rep := range pm.File.Replace {
		if modfile.IsDirectoryPath(rep.New.Path) {
			// Have local replacement, such as 'replace A => ../'.
			dep := []byte(rep.New.Path)
			start, end := rep.Syntax.Start.Byte, rep.Syntax.End.Byte
			i := bytes.Index(pm.Mapper.Content[start:end], dep)
			if i < 0 {
				continue
			}
			path := rep.New.Path
			if !filepath.IsAbs(path) {
				path = filepath.Join(fh.URI().DirPath(), path)
			}
			// jump to the go.mod file of replaced module.
			path = filepath.Join(filepath.Clean(path), "go.mod")
			l, err := toProtocolLink(pm.Mapper, protocol.URIFromPath(path).Path(), start+i, start+i+len(dep))
			if err != nil {
				return nil, err
			}
			links = append(links, l)
			continue
		}
	}

	for _, req := range pm.File.Require {
		if req.Syntax == nil {
			continue
		}
		// See golang/go#36998: don't link to modules matching GOPRIVATE.
		if snapshot.IsGoPrivatePath(req.Mod.Path) {
			continue
		}
		dep := []byte(req.Mod.Path)
		start, end := req.Syntax.Start.Byte, req.Syntax.End.Byte
		i := bytes.Index(pm.Mapper.Content[start:end], dep)
		if i == -1 {
			continue
		}

		mod := req.Mod
		// respect the replacement when constructing a module link.
		if m, ok := pm.ReplaceMap[req.Mod]; ok {
			// Have: 'replace A v1.2.3 => A vx.x.x' or 'replace A v1.2.3 => B vx.x.x'.
			mod = m
		} else if m, ok := pm.ReplaceMap[module.Version{Path: req.Mod.Path}]; ok &&
			!modfile.IsDirectoryPath(m.Path) { // exclude local replacement.
			// Have: 'replace A => A vx.x.x' or 'replace A => B vx.x.x'.
			mod = m
		}

		// Shift the start position to the location of the
		// dependency within the require statement.
		target := cache.BuildLink(snapshot.Options().LinkTarget, "mod/"+mod.String(), "")
		l, err := toProtocolLink(pm.Mapper, target, start+i, start+i+len(dep))
		if err != nil {
			return nil, err
		}
		links = append(links, l)
	}
	// TODO(ridersofrohan): handle links for replace and exclude directives.
	if syntax := pm.File.Syntax; syntax == nil {
		return links, nil
	}

	// Get all the links that are contained in the comments of the file.
	urlRegexp := xurls.Relaxed()
	for _, expr := range pm.File.Syntax.Stmt {
		comments := expr.Comment()
		if comments == nil {
			continue
		}
		for _, section := range [][]modfile.Comment{comments.Before, comments.Suffix, comments.After} {
			for _, comment := range section {
				l, err := findLinksInString(urlRegexp, comment.Token, comment.Start.Byte, pm.Mapper)
				if err != nil {
					return nil, err
				}
				links = append(links, l...)
			}
		}
	}
	return links, nil
}

// goLinks returns the set of hyperlink annotations for the specified Go file.
func goLinks(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.DocumentLink, error) {

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}

	var links []protocol.DocumentLink

	// Create links for import specs.
	if snapshot.Options().ImportShortcut.ShowLinks() {

		// If links are to pkg.go.dev, append module version suffixes.
		// This requires the import map from the package metadata. Ignore errors.
		var depsByImpPath map[golang.ImportPath]golang.PackageID
		if strings.ToLower(snapshot.Options().LinkTarget) == "pkg.go.dev" {
			if meta, err := snapshot.NarrowestMetadataForFile(ctx, fh.URI()); err == nil {
				depsByImpPath = meta.DepsByImpPath
			}
		}

		for _, imp := range pgf.File.Imports {
			importPath := metadata.UnquoteImportPath(imp)
			if importPath == "" {
				continue // bad import
			}
			// See golang/go#36998: don't link to modules matching GOPRIVATE.
			if snapshot.IsGoPrivatePath(string(importPath)) {
				continue
			}

			urlPath := string(importPath)

			// For pkg.go.dev, append module version suffix to package import path.
			if mp := snapshot.Metadata(depsByImpPath[importPath]); mp != nil && mp.Module != nil && cache.ResolvedPath(mp.Module) != "" && cache.ResolvedVersion(mp.Module) != "" {
				urlPath = strings.Replace(urlPath, mp.Module.Path, cache.ResolvedString(mp.Module), 1)
			}

			start, end, err := safetoken.Offsets(pgf.Tok, imp.Path.Pos(), imp.Path.End())
			if err != nil {
				return nil, err
			}
			targetURL := cache.BuildLink(snapshot.Options().LinkTarget, urlPath, "")
			// Account for the quotation marks in the positions.
			l, err := toProtocolLink(pgf.Mapper, targetURL, start+len(`"`), end-len(`"`))
			if err != nil {
				return nil, err
			}
			links = append(links, l)
		}
	}

	urlRegexp := xurls.Relaxed()

	// Gather links found in string literals.
	var str []*ast.BasicLit
	for curLit := range pgf.Cursor().Preorder((*ast.BasicLit)(nil)) {
		lit := curLit.Node().(*ast.BasicLit)
		if lit.Kind == token.STRING {
			if _, ok := curLit.Parent().Node().(*ast.ImportSpec); ok {
				continue // ignore import strings
			}
			str = append(str, lit)
		}
	}
	for _, s := range str {
		strOffset, err := safetoken.Offset(pgf.Tok, s.Pos())
		if err != nil {
			return nil, err
		}
		l, err := findLinksInString(urlRegexp, s.Value, strOffset, pgf.Mapper)
		if err != nil {
			return nil, err
		}
		links = append(links, l...)
	}

	// Gather links found in comments.
	for _, commentGroup := range pgf.File.Comments {
		for _, comment := range commentGroup.List {
			commentOffset, err := safetoken.Offset(pgf.Tok, comment.Pos())
			if err != nil {
				return nil, err
			}
			l, err := findLinksInString(urlRegexp, comment.Text, commentOffset, pgf.Mapper)
			if err != nil {
				return nil, err
			}
			links = append(links, l...)
		}
	}

	return links, nil
}

// acceptedSchemes controls the schemes that URLs must have to be shown to the
// user. Other schemes can't be opened by LSP clients, so linkifying them is
// distracting. See golang/go#43990.
var acceptedSchemes = map[string]bool{
	"http":  true,
	"https": true,
}

// findLinksInString is the user-supplied regular expression to match URL.
// srcOffset is the start offset of 'src' within m's file.
func findLinksInString(urlRegexp *regexp.Regexp, src string, srcOffset int, m *protocol.Mapper) ([]protocol.DocumentLink, error) {
	var links []protocol.DocumentLink
	for _, index := range urlRegexp.FindAllIndex([]byte(src), -1) {
		start, end := index[0], index[1]
		link := src[start:end]
		linkURL, err := url.Parse(link)
		// Fallback: Linkify IP addresses as suggested in golang/go#18824.
		if err != nil {
			linkURL, err = url.Parse("//" + link)
			// Not all potential links will be valid, so don't return this error.
			if err != nil {
				continue
			}
		}
		// If the URL has no scheme, use https.
		if linkURL.Scheme == "" {
			linkURL.Scheme = "https"
		}
		if !acceptedSchemes[linkURL.Scheme] {
			continue
		}

		l, err := toProtocolLink(m, linkURL.String(), srcOffset+start, srcOffset+end)
		if err != nil {
			return nil, err
		}
		links = append(links, l)
	}
	// Handle golang/go#1234-style links.
	r := getIssueRegexp()
	for _, index := range r.FindAllIndex([]byte(src), -1) {
		start, end := index[0], index[1]
		matches := r.FindStringSubmatch(src)
		if len(matches) < 4 {
			continue
		}
		org, repo, number := matches[1], matches[2], matches[3]
		targetURL := fmt.Sprintf("https://github.com/%s/%s/issues/%s", org, repo, number)
		l, err := toProtocolLink(m, targetURL, srcOffset+start, srcOffset+end)
		if err != nil {
			return nil, err
		}
		links = append(links, l)
	}
	return links, nil
}

func getIssueRegexp() *regexp.Regexp {
	once.Do(func() {
		issueRegexp = regexp.MustCompile(`(\w+)/([\w-]+)#([0-9]+)`)
	})
	return issueRegexp
}

var (
	once        sync.Once
	issueRegexp *regexp.Regexp
)

func toProtocolLink(m *protocol.Mapper, targetURL string, start, end int) (protocol.DocumentLink, error) {
	rng, err := m.OffsetRange(start, end)
	if err != nil {
		return protocol.DocumentLink{}, err
	}
	return protocol.DocumentLink{
		Range:  rng,
		Target: &targetURL,
	}, nil
}


================================================
FILE: gopls/internal/server/prompt.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"
	"math/rand"
	"os"
	"path/filepath"
	"strconv"
	"testing"
	"time"

	"golang.org/x/telemetry"
	"golang.org/x/telemetry/counter"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

// promptTimeout is the amount of time we wait for an ongoing prompt before
// prompting again. This gives the user time to reply. However, at some point
// we must assume that the client is not displaying the prompt, the user is
// ignoring it, or the prompt has been disrupted in some way (e.g. by a gopls
// crash).
const promptTimeout = 24 * time.Hour

// gracePeriod is the amount of time we wait before sufficient telemetry data
// is accumulated in the local directory, so users can have time to review
// what kind of information will be collected and uploaded when prompting starts.
const gracePeriod = 7 * 24 * time.Hour

// samplesPerMille is the prompt probability.
// Token is an integer between [1, 1000] and is assigned when maybePromptForTelemetry
// is called first time. Only the user with a token ∈ [1, samplesPerMille]
// will be considered for prompting.
const samplesPerMille = 10 // 1% sample rate

// The following constants are used for testing telemetry integration.
const (
	TelemetryPromptWorkTitle    = "Checking telemetry prompt"     // progress notification title, for awaiting in tests
	GoplsConfigDirEnvvar        = "GOPLS_CONFIG_DIR"              // overridden for testing
	FakeTelemetryModefileEnvvar = "GOPLS_FAKE_TELEMETRY_MODEFILE" // overridden for testing
	FakeSamplesPerMille         = "GOPLS_FAKE_SAMPLES_PER_MILLE"  // overridden for testing
	TelemetryYes                = "Yes, I'd like to help."
	TelemetryNo                 = "No, thanks."
)

// The following environment variables may be set by the client.
// Exported for testing telemetry integration.
const (
	GoTelemetryGoplsClientStartTimeEnvvar = "GOTELEMETRY_GOPLS_CLIENT_START_TIME" // telemetry start time recorded in client
	GoTelemetryGoplsClientTokenEnvvar     = "GOTELEMETRY_GOPLS_CLIENT_TOKEN"      // sampling token
)

// getenv returns the effective environment variable value for the provided
// key, looking up the key in the session environment before falling back on
// the process environment.
func (s *server) getenv(key string) string {
	if v, ok := s.Options().Env[key]; ok {
		return v
	}
	return os.Getenv(key)
}

// telemetryMode returns the current effective telemetry mode.
// By default this is x/telemetry.Mode(), but it may be overridden for tests.
func (s *server) telemetryMode() string {
	if fake := s.getenv(FakeTelemetryModefileEnvvar); fake != "" {
		if data, err := os.ReadFile(fake); err == nil {
			return string(data)
		}
		return "local"
	}
	return telemetry.Mode()
}

// setTelemetryMode sets the current telemetry mode.
// By default this calls x/telemetry.SetMode, but it may be overridden for
// tests.
func (s *server) setTelemetryMode(mode string) error {
	if fake := s.getenv(FakeTelemetryModefileEnvvar); fake != "" {
		return os.WriteFile(fake, []byte(mode), 0666)
	}
	return telemetry.SetMode(mode)
}

// maybePromptForTelemetry checks for the right conditions, and then prompts
// the user to ask if they want to enable Go telemetry uploading. If the user
// responds 'Yes', the telemetry mode is set to "on".
//
// The actual conditions for prompting are defensive, erring on the side of not
// prompting.
// If enabled is false, this will not prompt the user in any condition,
// but will send work progress reports to help testing.
func (s *server) maybePromptForTelemetry(ctx context.Context, enabled bool) {
	if s.Options().VerboseWorkDoneProgress {
		work := s.progress.Start(ctx, TelemetryPromptWorkTitle, "Checking if gopls should prompt about telemetry...", nil, nil)
		defer work.End(ctx, "Done.")
	}

	errorf := func(format string, args ...any) {
		err := fmt.Errorf(format, args...)
		event.Error(ctx, "telemetry prompt failed", err)
	}

	// Only prompt if we can read/write the prompt config file.
	configDir := s.getenv(GoplsConfigDirEnvvar) // set for testing
	if configDir == "" && testing.Testing() {
		// Unless tests set GoplsConfigDirEnvvar, the prompt is a no op.
		// We don't want tests to interact with os.UserConfigDir().
		return
	}
	if configDir == "" {
		userDir, err := os.UserConfigDir()
		if err != nil {
			errorf("unable to determine user config dir: %v", err)
			return
		}
		configDir = filepath.Join(userDir, "gopls")
	}

	// Read the current prompt file.

	var (
		promptDir  = filepath.Join(configDir, "prompt")    // prompt configuration directory
		promptFile = filepath.Join(promptDir, "telemetry") // telemetry prompt file
	)

	// prompt states, stored in the prompt file
	const (
		pUnknown  = ""        // first time
		pNotReady = "-"       // user is not asked yet (either not sampled or not past the grace period)
		pYes      = "yes"     // user said yes
		pNo       = "no"      // user said no
		pPending  = "pending" // current prompt is still pending
		pFailed   = "failed"  // prompt was asked but failed
	)
	validStates := map[string]bool{
		pNotReady: true,
		pYes:      true,
		pNo:       true,
		pPending:  true,
		pFailed:   true,
	}

	// Parse the current prompt file.
	var (
		state    = pUnknown
		attempts = 0 // number of times we've asked already

		// the followings are recorded after gopls v0.17+.
		token        = 0   // valid token is [1, 1000]
		creationTime int64 // unix time sec
	)
	if content, err := os.ReadFile(promptFile); err == nil {
		if n, _ := fmt.Sscanf(string(content), "%s %d %d %d", &state, &attempts, &creationTime, &token); (n == 2 || n == 4) && validStates[state] {
			// successfully parsed!
			//  ~ v0.16: must have only two fields, state and attempts.
			//  v0.17 ~: must have all four fields.
		} else {
			state, attempts, creationTime, token = pUnknown, 0, 0, 0
			// TODO(hyangah): why do we want to present this as an error to user?
			errorf("malformed prompt result %q", string(content))
		}
	} else if !os.IsNotExist(err) {
		errorf("reading prompt file: %v", err)
		// Something went wrong. Since we don't know how many times we've asked the
		// prompt, err on the side of not asking.
		//
		// But record this in telemetry, in case some users enable telemetry by
		// other means.
		counter.New("gopls/telemetryprompt/corrupted").Inc()
		return
	}

	counter.New(fmt.Sprintf("gopls/telemetryprompt/attempts:%d", attempts)).Inc()

	// Check terminal conditions.

	if state == pYes {
		// Prompt has been accepted.
		//
		// We record this counter for every gopls session, rather than when the
		// prompt actually accepted below, because if we only recorded it in the
		// counter file at the time telemetry is enabled, we'd never upload it,
		// because we exclude any counter files that overlap with a time period
		// that has telemetry uploading is disabled.
		counter.New("gopls/telemetryprompt/accepted").Inc()
		return
	}
	if state == pNo {
		// Prompt has been declined. In most cases, this means we'll never see the
		// counter below, but it's possible that the user may enable telemetry by
		// other means later on. If we see a significant number of users that have
		// accepted telemetry but declined the prompt, it may be an indication that
		// the prompt is not working well.
		counter.New("gopls/telemetryprompt/declined").Inc()
		return
	}
	if attempts >= 5 { // pPending or pFailed
		// We've tried asking enough; give up. Record that the prompt expired, in
		// case the user decides to enable telemetry by other means later on.
		// (see also the pNo case).
		counter.New("gopls/telemetryprompt/expired").Inc()
		return
	}

	// We only check enabled after (1) the work progress is started, and (2) the
	// prompt file has been read. (1) is for testing purposes, and (2) is so that
	// we record the "gopls/telemetryprompt/accepted" counter for every session.
	if !enabled {
		return // prompt is disabled
	}

	if s.telemetryMode() == "on" || s.telemetryMode() == "off" {
		// Telemetry is already on or explicitly off -- nothing to ask about.
		return
	}

	// Transition: pUnknown -> pNotReady
	if state == pUnknown {
		// First time; we need to make the prompt dir.
		if err := os.MkdirAll(promptDir, 0777); err != nil {
			errorf("creating prompt dir: %v", err)
			return
		}
		state = pNotReady
	}

	// Correct missing values.
	if creationTime == 0 {
		creationTime = time.Now().Unix()
		if v := s.getenv(GoTelemetryGoplsClientStartTimeEnvvar); v != "" {
			if sec, err := strconv.ParseInt(v, 10, 64); err == nil && sec > 0 {
				creationTime = sec
			}
		}
	}
	if token == 0 {
		token = rand.Intn(1000) + 1
		if v := s.getenv(GoTelemetryGoplsClientTokenEnvvar); v != "" {
			if tok, err := strconv.Atoi(v); err == nil && 1 <= tok && tok <= 1000 {
				token = tok
			}
		}
	}

	// Transition: pNotReady -> pPending if sampled
	if state == pNotReady {
		threshold := samplesPerMille
		if v := s.getenv(FakeSamplesPerMille); v != "" {
			if t, err := strconv.Atoi(v); err == nil {
				threshold = t
			}
		}
		if token <= threshold && time.Now().Unix()-creationTime > gracePeriod.Milliseconds()/1000 {
			state = pPending
		}
	}

	// Acquire the lock and write the updated state to the prompt file before actually
	// prompting.
	//
	// This ensures that the prompt file is writeable, and that we increment the
	// attempt counter before we prompt, so that we don't end up in a failure
	// mode where we keep prompting and then failing to record the response.

	release, ok, err := acquireLockFile(promptFile)
	if err != nil {
		errorf("acquiring prompt: %v", err)
		return
	}
	if !ok {
		// Another process is making decision.
		return
	}
	defer release()

	if state != pNotReady { // pPending or pFailed
		attempts++
	}

	pendingContent := fmt.Appendf(nil, "%s %d %d %d", state, attempts, creationTime, token)
	if err := os.WriteFile(promptFile, pendingContent, 0666); err != nil {
		errorf("writing pending state: %v", err)
		return
	}

	if state == pNotReady {
		return
	}

	var prompt = `Go telemetry helps us improve Go by periodically sending anonymous metrics and crash reports to the Go team. Learn more at https://go.dev/doc/telemetry.

Would you like to enable Go telemetry?
`
	if s.Options().LinkifyShowMessage {
		prompt = `Go telemetry helps us improve Go by periodically sending anonymous metrics and crash reports to the Go team. Learn more at [go.dev/doc/telemetry](https://go.dev/doc/telemetry).

Would you like to enable Go telemetry?
`
	}
	// TODO(rfindley): investigate a "tell me more" action in combination with ShowDocument.
	action, err := showMessageRequest(ctx, s.client, protocol.Info, prompt, TelemetryYes, TelemetryNo)
	if err != nil {
		errorf("ShowMessageRequest failed: %v", err)
	}

	message := func(typ protocol.MessageType, msg string) {
		if !showMessage(ctx, s.client, typ, msg) {
			// Make sure we record that "telemetry prompt failed".
			errorf("showMessage failed: %v", err)
		}
	}

	result := pFailed
	if action == "" {
		// e.g. dialog was dismissed
		errorf("no response")
	} else {
		// Response matches MessageActionItem.Title.
		switch action {
		case TelemetryYes:
			result = pYes
			if err := s.setTelemetryMode("on"); err == nil {
				message(protocol.Info, telemetryOnMessage(s.Options().LinkifyShowMessage))
			} else {
				errorf("enabling telemetry failed: %v", err)
				msg := fmt.Sprintf("Failed to enable Go telemetry: %v\nTo enable telemetry manually, please run `go run golang.org/x/telemetry/cmd/gotelemetry@latest on`", err)
				message(protocol.Error, msg)
			}

		case TelemetryNo:
			result = pNo
		default:
			errorf("unrecognized response %q", action)
			message(protocol.Error, fmt.Sprintf("Unrecognized response %q", action))
		}
	}
	resultContent := fmt.Appendf(nil, "%s %d %d %d", result, attempts, creationTime, token)
	if err := os.WriteFile(promptFile, resultContent, 0666); err != nil {
		errorf("error writing result state to prompt file: %v", err)
	}
}

// showMessageRequest causes the client to show a prompt that the user can respond to.
// It returns the title of the action the user selected, or "" if the user dismissed the prompt.
func showMessageRequest(ctx context.Context, cli protocol.Client, typ protocol.MessageType, message string, actions ...string) (string, error) {
	var actionItems []protocol.MessageActionItem
	for _, action := range actions {
		actionItems = append(actionItems, protocol.MessageActionItem{Title: action})
	}
	params := &protocol.ShowMessageRequestParams{
		Type:    typ,
		Message: message,
		Actions: actionItems,
	}
	// Timeout used to wait for the user to respond to a message request.
	const timeout = 15 * time.Second
	ctx, cancel := context.WithTimeout(ctx, timeout)
	defer cancel()

	result, err := cli.ShowMessageRequest(ctx, params)

	if err != nil {
		if cause := context.Cause(ctx); cause == context.DeadlineExceeded || cause == context.Canceled {
			return "", nil
		}
		return "", err
	}
	if result == nil {
		return "", nil // User dismissed the notification
	}
	return result.Title, nil
}

func telemetryOnMessage(linkify bool) string {
	format := `Thank you. Telemetry uploading is now enabled.

To disable telemetry uploading, run %s.
`
	var runCmd = "`go run golang.org/x/telemetry/cmd/gotelemetry@latest local`"
	if linkify {
		runCmd = "[gotelemetry local](https://golang.org/x/telemetry/cmd/gotelemetry)"
	}
	return fmt.Sprintf(format, runCmd)
}

// acquireLockFile attempts to "acquire a lock" for writing to path.
//
// This is achieved by creating an exclusive lock file at <path>.lock. Lock
// files expire after a period, at which point acquireLockFile will remove and
// recreate the lock file.
//
// acquireLockFile fails if path is in a directory that doesn't exist.
func acquireLockFile(path string) (func(), bool, error) {
	lockpath := path + ".lock"
	fi, err := os.Stat(lockpath)
	if err == nil {
		if time.Since(fi.ModTime()) > promptTimeout {
			_ = os.Remove(lockpath) // ignore error
		} else {
			return nil, false, nil
		}
	} else if !os.IsNotExist(err) {
		return nil, false, fmt.Errorf("statting lockfile: %v", err)
	}

	f, err := os.OpenFile(lockpath, os.O_CREATE|os.O_EXCL, 0666)
	if err != nil {
		if os.IsExist(err) {
			return nil, false, nil
		}
		return nil, false, fmt.Errorf("creating lockfile: %v", err)
	}
	fi, err = f.Stat()
	if err != nil {
		return nil, false, err
	}
	release := func() {
		_ = f.Close() // ignore error
		fi2, err := os.Stat(lockpath)
		if err == nil && os.SameFile(fi, fi2) {
			// Only clean up the lockfile if it's the same file we created.
			// Otherwise, our lock has expired and something else has the lock.
			//
			// There's a race here, in that the file could have changed since the
			// stat above; but given that we've already waited 24h this is extremely
			// unlikely, and acceptable.
			_ = os.Remove(lockpath)
		}
	}
	return release, true, nil
}


================================================
FILE: gopls/internal/server/prompt_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"path/filepath"
	"sync"
	"sync/atomic"
	"testing"
)

func TestAcquireFileLock(t *testing.T) {
	name := filepath.Join(t.TempDir(), "config.json")

	const concurrency = 100
	var acquired int32
	var releasers [concurrency]func()
	defer func() {
		for _, r := range releasers {
			if r != nil {
				r()
			}
		}
	}()

	var wg sync.WaitGroup
	for i := range releasers {
		wg.Go(func() {

			release, ok, err := acquireLockFile(name)
			if err != nil {
				t.Errorf("Acquire failed: %v", err)
				return
			}
			if ok {
				atomic.AddInt32(&acquired, 1)
				releasers[i] = release
			}
		})
	}

	wg.Wait()

	if acquired != 1 {
		t.Errorf("Acquire succeeded %d times, expected exactly 1", acquired)
	}
}

func TestReleaseAndAcquireFileLock(t *testing.T) {
	name := filepath.Join(t.TempDir(), "config.json")

	acquire := func() (func(), bool) {
		t.Helper()
		release, ok, err := acquireLockFile(name)
		if err != nil {
			t.Fatal(err)
		}
		return release, ok
	}

	release, ok := acquire()
	if !ok {
		t.Fatal("failed to Acquire")
	}
	if release2, ok := acquire(); ok {
		release()
		release2()
		t.Fatalf("Acquire succeeded unexpectedly")
	}

	release()
	release3, ok := acquire()
	release3()
	if !ok {
		t.Fatalf("failed to Acquire")
	}
}


================================================
FILE: gopls/internal/server/references.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/mod"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/internal/event"
)

func (s *server) References(ctx context.Context, params *protocol.ReferenceParams) (_ []protocol.Location, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("references")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.References", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Tmpl:
		return template.References(ctx, snapshot, fh, params)
	case file.Go:
		return golang.References(ctx, snapshot, fh, params.Range, params.Context.IncludeDeclaration)
	case file.Mod:
		return mod.References(ctx, snapshot, fh, params)
	}
	return nil, nil // empty result
}


================================================
FILE: gopls/internal/server/rename.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) Rename(ctx context.Context, params *protocol.RenameParams) (*protocol.WorkspaceEdit, error) {
	countRename.Inc()
	ctx, done := event.Start(ctx, "server.Rename", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if kind := snapshot.FileKind(fh); kind != file.Go {
		return nil, fmt.Errorf("cannot rename in file of type %s", kind)
	}

	changes, err := golang.Rename(ctx, snapshot, fh, params.Range, params.NewName)
	if err != nil {
		return nil, err
	}
	return protocol.NewWorkspaceEdit(changes...), nil
}

// PrepareRename implements the textDocument/prepareRename handler. It may
// return (nil, nil) if there is no rename at the cursor position, but it is
// not desirable to display an error to the user.
//
// TODO(rfindley): why wouldn't we want to show an error to the user, if the
// user initiated a rename request at the cursor?
func (s *server) PrepareRename(ctx context.Context, params *protocol.PrepareRenameParams) (*protocol.PrepareRenamePlaceholder, error) {
	ctx, done := event.Start(ctx, "server.PrepareRename", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if kind := snapshot.FileKind(fh); kind != file.Go {
		return nil, fmt.Errorf("cannot rename in file of type %s", kind)
	}

	// Do not return errors here, as it adds clutter.
	// Returning a nil result means there is not a valid rename.
	item, usererr, err := golang.PrepareRename(ctx, snapshot, fh, params.Range)
	if err != nil {
		// Return usererr here rather than err, to avoid cluttering the UI with
		// internal error details.
		return nil, usererr
	}
	return &protocol.PrepareRenamePlaceholder{
		Range:       item.Range,
		Placeholder: item.Text,
	}, nil
}


================================================
FILE: gopls/internal/server/resolve.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"
	"slices"
	"strings"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
)

// Ths file contains the code to mediate user dialogs in the client

// The logical flow is as follows:
// 1. Client sends 'textDocument/codeAction'
//    gopls respond with one or more CodeActions, including one with kind either
//    'refactor.rewrite.addTags' or 'refactor.rewrite.removeTags'
// 2. Client sends 'codeAction/resolve' with the selected CodeActions
//    gopls returns the same CodeAction
// 3. Client sends 'workspace/executeCommand' to get the dialog form
//    gopls responds with the form to display to the user
// 4. Client sends 'command/resolve' with the filled out form
//    gopls responds, with 'workspace/applyEdit' saying what to do
// 5. Client return ApplyWorkspaceEditResult with applied = true
// 6. Client sends a textDocument/didChange notification, with the edits applied (optional)

// In vscode-go, because it is a standard LSP client,
// cannot do step 4 as described. Instead
// it calls "workspace/executeCommand" with command 'gopls.lsp'
// and parameter.Method "command/resolve".
//
// ExecuteCommand() calls command.Dispatch() which calls LSP()
// which calls protocol.ServerDispatchCall("command/resolve")
// which calls ResolveCommand. command.Dispatch() switches on param.Command and LSP() passes param.Method
// to ServerDispatchCall

// The neovim flow is simpler, as 'command/resolve' can be invoked directly.

var AddTagsForm = []protocol.FormField{
	{
		Description: `comma-separated list of tags to add; e.g.. "json,xml"`,
		Type:        protocol.FormFieldTypeString{Kind: "string"},
		Default:     "json",
	},
	{
		Description: `transform rule for added tags, e.g., "camelcase' or 'snakecase"`,
		Type: protocol.FormFieldTypeEnum{
			Kind: "enum",
			Entries: []protocol.FormEnumEntry{
				{
					// MyField -> myField
					Value:       "camelcase",
					Description: "camelcase",
				},
				{
					// MyField -> my-field
					Value:       "lispcase",
					Description: "lispcase",
				},
				{
					// MyField -> MyField
					Value:       "pascalcase",
					Description: "pascalcase",
				},
				{
					// MyField -> My Field
					Value:       "titlecase",
					Description: "titlecase",
				},
				{
					// MyField -> my_field
					Value:       "snakecase",
					Description: "snakecase",
				},
				{
					// keep the existing field name
					Value:       "keep",
					Description: "keep",
				},
			},
		},
		Default: "camelcase",
	},
}

var RemoveTagsForm = []protocol.FormField{
	{
		Description: `comma-separated list of tags to remove; e.g., "json,xml"`,
		Type:        protocol.FormFieldTypeString{Kind: "string"},
		Default:     "json", // TODO(?): put the existing tags here?
	},
}

// ResolveComamnd is called indirectly from WorkspaceCommand(), explained above.
func (s *server) ResolveCommand(ctx context.Context, param *protocol.ExecuteCommandParams) (*protocol.ExecuteCommandParams, error) {
	switch param.Command {
	case "gopls.modify_tags":
		return resolveModifyTags(param)
	}
	return nil, notImplemented(fmt.Sprintf("ResolveCommand(%s)", param.Command))
}

func resolveModifyTags(param *protocol.ExecuteCommandParams) (*protocol.ExecuteCommandParams, error) {
	var a0 command.ModifyTagsArgs
	if err := command.UnmarshalArgs(param.Arguments, &a0); err != nil {
		return nil, err
	}
	switch a0.Modification {
	case "add":
		switch len(param.FormAnswers) {
		case 0: // first call, return the form
			param.FormFields = AddTagsForm
			return param, nil
		case 2: // second call, process the form
			var ok bool
			if a0.Add, ok = param.FormAnswers[0].(string); !ok {
				return nil, fmt.Errorf("invalid type of first value, want string: %v", param.FormAnswers[0])
			}

			if slices.Contains(strings.Split(a0.Add, ","), "") {
				// TODO(pjw): instead filter AddTagsForm to remove empty tags and tags containing spaces
				form := slices.Clone(AddTagsForm)
				form[0].Error = "input tags should not contain empty tag"
				param.FormFields = form
				return param, nil
			}

			if a0.Transform, ok = param.FormAnswers[1].(string); !ok {
				return nil, fmt.Errorf("invalid type of second value, want string: %v", param.FormAnswers[1])
			}
			// PJW: what happens when the user enters a bad value? (i think the client handles it)

			raw, err := command.MarshalArgs(a0)
			if err != nil {
				return nil, err
			}

			param.FormAnswers = nil
			param.FormFields = nil
			param.Arguments = raw
			return param, nil
		default:
			return nil, fmt.Errorf("modify tags command expecting 1 value from client, got %v", len(param.FormAnswers))
		}
	case "remove":
		switch len(param.FormAnswers) {
		case 0: // first call, return the form
			// TODO? show the user the current list of tags?
			param.FormFields = RemoveTagsForm
			return param, nil
		case 1: // second call, process the form
			var ok bool
			if a0.Remove, ok = param.FormAnswers[0].(string); !ok {
				return nil, fmt.Errorf("invalid type of value, want string: %v", param.FormAnswers[0])
			}
			raw, err := command.MarshalArgs(a0)
			if err != nil {
				return nil, err
			}

			param.FormAnswers = nil
			param.FormFields = nil
			param.Arguments = raw
			return param, nil
		default:
			return nil, fmt.Errorf("modify tags command expecting 1 value from client, got %v", len(param.FormAnswers))
		}
	default:
		return nil, fmt.Errorf("unsupported modify tags operation: %s", a0.Modification)
	}
}


================================================
FILE: gopls/internal/server/selection_range.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/gopls/internal/cache/parsego"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

// SelectionRange defines the textDocument/selectionRange feature,
// which, given a list of positions within a file,
// reports a linked list of enclosing syntactic blocks, innermost first.
//
// See https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#textDocument_selectionRange.
//
// This feature can be used by a client to implement "expand selection" in a
// language-aware fashion. Multiple input positions are supported to allow
// for multiple cursors, and the entire path up to the whole document is
// returned for each cursor to avoid multiple round-trips when the user is
// likely to issue this command multiple times in quick succession.
func (s *server) SelectionRange(ctx context.Context, params *protocol.SelectionRangeParams) ([]protocol.SelectionRange, error) {
	ctx, done := event.Start(ctx, "server.SelectionRange")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if kind := snapshot.FileKind(fh); kind != file.Go {
		return nil, fmt.Errorf("SelectionRange not supported for file of type %s", kind)
	}

	pgf, err := snapshot.ParseGo(ctx, fh, parsego.Full)
	if err != nil {
		return nil, err
	}

	result := make([]protocol.SelectionRange, len(params.Positions))
	for i, protocolPos := range params.Positions {
		pos, err := pgf.PositionPos(protocolPos)
		if err != nil {
			return nil, err
		}

		path, _ := astutil.PathEnclosingInterval(pgf.File, pos, pos)

		tail := &result[i] // tail of the Parent linked list, built head first

		for j, node := range path {
			rng, err := pgf.NodeRange(node)
			if err != nil {
				return nil, err
			}

			// Add node to tail.
			if j > 0 {
				tail.Parent = &protocol.SelectionRange{}
				tail = tail.Parent
			}
			tail.Range = rng
		}
	}

	return result, nil
}


================================================
FILE: gopls/internal/server/semantic.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/internal/event"
)

func (s *server) SemanticTokensFull(ctx context.Context, params *protocol.SemanticTokensParams) (*protocol.SemanticTokens, error) {
	return s.semanticTokens(ctx, params.TextDocument, nil)
}

func (s *server) SemanticTokensRange(ctx context.Context, params *protocol.SemanticTokensRangeParams) (*protocol.SemanticTokens, error) {
	return s.semanticTokens(ctx, params.TextDocument, &params.Range)
}

func (s *server) semanticTokens(ctx context.Context, td protocol.TextDocumentIdentifier, rng *protocol.Range) (*protocol.SemanticTokens, error) {
	ctx, done := event.Start(ctx, "server.semanticTokens", label.URI.Of(td.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, td.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if snapshot.Options().SemanticTokens {
		switch snapshot.FileKind(fh) {
		case file.Tmpl:
			return template.SemanticTokens(ctx, snapshot, fh.URI())
		case file.Go:
			return golang.SemanticTokens(ctx, snapshot, fh, rng)
		}
	}

	// Not enabled, or unsupported file type: return empty result.
	//
	// Returning an empty response is necessary to invalidate
	// semantic tokens in VS Code (and perhaps other editors).
	// Previously, we returned an error, but that had the side effect
	// of noisy "semantictokens are disabled" logs on every keystroke.
	//
	// We must return a non-nil Data slice for JSON serialization.
	// We do not return an empty field with "omitempty" set,
	// as it is not marked optional in the protocol (golang/go#67885).
	return &protocol.SemanticTokens{Data: []uint32{}}, nil
}


================================================
FILE: gopls/internal/server/server.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package server defines gopls' implementation of the LSP server
// interface, [protocol.Server]. Call [New] to create an instance.
package server

import (
	"context"
	"crypto/rand"
	"embed"
	"encoding/base64"
	"fmt"
	"io"
	"io/fs"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	paths "path"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cache/metadata"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/golang/splitpkg"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/event"
)

// New creates an LSP server and binds it to handle incoming client
// messages on the supplied stream.
func New(session *cache.Session, client protocol.ClientCloser, options *settings.Options) protocol.Server {
	const concurrentAnalyses = 1
	// If this assignment fails to compile after a protocol
	// upgrade, it means that one or more new methods need new
	// stub declarations in unimplemented.go.
	return &server{
		diagnostics:         make(map[protocol.DocumentURI]*fileDiagnostics),
		watchedGlobPatterns: nil, // empty
		changedFiles:        make(map[protocol.DocumentURI]unit),
		session:             session,
		client:              client,
		diagnosticsSema:     make(chan unit, concurrentAnalyses),
		progress:            progress.NewTracker(client),
		options:             options,
		viewsToDiagnose:     make(map[*cache.View]uint64),
	}
}

type serverState int

const (
	serverCreated      = serverState(iota)
	serverInitializing // set once the server has received "initialize" request
	serverInitialized  // set once the server has received "initialized" request
	serverShutDown
)

func (s serverState) String() string {
	switch s {
	case serverCreated:
		return "created"
	case serverInitializing:
		return "initializing"
	case serverInitialized:
		return "initialized"
	case serverShutDown:
		return "shutDown"
	}
	return fmt.Sprintf("(unknown state: %d)", int(s))
}

// server implements the [protocol.Server] interface.
//
// A server holds the server-side state of a single client/server
// session or connection; it conceptually corresponds to a single call
// to accept(2), not to listen(2) as the name "server" might suggest.
type server struct {
	client protocol.ClientCloser

	stateMu sync.Mutex
	state   serverState
	// notifications generated before serverInitialized
	notifications []*protocol.ShowMessageParams

	session *cache.Session

	// changedFiles tracks files for which there has been a textDocument/didChange.
	changedFilesMu sync.Mutex
	changedFiles   map[protocol.DocumentURI]unit

	// folders is only valid between initialize and initialized, and holds the
	// set of folders to build views for when we are ready.
	// Only the valid, non-empty 'file'-scheme URIs will be added.
	pendingFolders []protocol.WorkspaceFolder

	// watchedGlobPatterns is the set of glob patterns that we have requested
	// the client watch on disk. It will be updated as the set of directories
	// that the server should watch changes.
	// The map field may be reassigned but the map is immutable.
	watchedGlobPatternsMu  sync.Mutex
	watchedGlobPatterns    map[protocol.RelativePattern]unit
	watchRegistrationCount int

	diagnosticsMu sync.Mutex // guards map and its values
	diagnostics   map[protocol.DocumentURI]*fileDiagnostics

	// diagnosticsSema limits the concurrency of diagnostics runs, which can be
	// expensive.
	diagnosticsSema chan unit

	progress *progress.Tracker

	// When the workspace fails to load, we show its status through a progress
	// report with an error message.
	criticalErrorStatusMu sync.Mutex
	criticalErrorStatus   *progress.WorkDone

	// Track an ongoing CPU profile created with the StartProfile command and
	// terminated with the StopProfile command.
	ongoingProfileMu sync.Mutex
	ongoingProfile   *os.File // if non-nil, an ongoing profile is writing to this file

	// Track most recently requested options.
	optionsMu sync.Mutex
	options   *settings.Options

	// Track the most recent completion results, for measuring completion efficacy
	efficacyMu      sync.Mutex
	efficacyURI     protocol.DocumentURI
	efficacyVersion int32
	efficacyItems   []protocol.CompletionItem
	efficacyPos     protocol.Position

	// Web server (for package documentation, etc) associated with this
	// LSP server. Opened on demand, and closed during LSP Shutdown.
	webOnce sync.Once
	web     *web
	webErr  error

	// # Modification tracking and diagnostics
	//
	// For the purpose of tracking diagnostics, we need a monotonically
	// increasing clock. Each time a change occurs on the server, this clock is
	// incremented and the previous diagnostics pass is cancelled. When the
	// changed is processed, the Session (via DidModifyFiles) determines which
	// Views are affected by the change and these views are added to the
	// viewsToDiagnose set. Then the server calls diagnoseChangedViews
	// in a separate goroutine. Any Views that successfully complete their
	// diagnostics are removed from the viewsToDiagnose set, provided they haven't
	// been subsequently marked for re-diagnosis (as determined by the latest
	// modificationID referenced by viewsToDiagnose).
	//
	// In this way, we enforce eventual completeness of the diagnostic set: any
	// views requiring diagnosis are diagnosed, though possibly at a later point
	// in time. Notably, the logic in Session.DidModifyFiles to determines if a
	// view needs diagnosis considers whether any packages in the view were
	// invalidated. Consider the following sequence of snapshots for a given view
	// V:
	//
	//     C1    C2
	//  S1 -> S2 -> S3
	//
	// In this case, suppose that S1 was fully type checked, and then two changes
	// C1 and C2 occur in rapid succession, to a file in their package graph but
	// perhaps not enclosed by V's root.  In this case, the logic of
	// DidModifyFiles will detect that V needs to be reloaded following C1. In
	// order for our eventual consistency to be sound, we need to avoid the race
	// where S2 is being diagnosed, C2 arrives, and S3 is not detected as needing
	// diagnosis because the relevant package has not yet been computed in S2. To
	// achieve this, we only remove V from viewsToDiagnose if the diagnosis of S2
	// completes before C2 is processed, which we can confirm by checking
	// S2.BackgroundContext().
	modificationMu        sync.Mutex
	cancelPrevDiagnostics func()
	viewsToDiagnose       map[*cache.View]uint64 // View -> modification at which it last required diagnosis
	lastModificationID    uint64                 // incrementing clock

	runGovulncheckInProgress atomic.Bool
}

func (s *server) WorkDoneProgressCancel(ctx context.Context, params *protocol.WorkDoneProgressCancelParams) error {
	ctx, done := event.Start(ctx, "server.WorkDoneProgressCancel")
	defer done()

	return s.progress.Cancel(params.Token)
}

// web encapsulates the web server associated with an LSP server.
// It is used for package documentation and other queries
// where HTML makes more sense than a client editor UI.
//
// Example URL:
//
//	http://127.0.0.1:PORT/gopls/SECRET/...
//
// where
//   - PORT is the random port number;
//   - "gopls" helps the reader guess which program is the server;
//   - SECRET is the 64-bit token; and
//   - ... is the material part of the endpoint.
//
// Valid endpoints:
//
//	open?file=%s&line=%d&col=%d        - open a file
//	pkg/PKGPATH?view=%s                - show doc for package in a given view
//	assembly?pkg=%s&view=%s&symbol=%s  - show assembly of specified func symbol
//	freesymbols?file=%s&range=%d:%d:%d:%d:&view=%s - show report of free symbols
//	splitpkg?pkg=%s&view=%s            - show "split package" HTML for given package/view
//	splitpkg-json?pkg=%s&view=%s       - query component dependency graph for given package/view
//	splitpkg-components?pkg=%s&view=%s - update component definitions for given package/view
type web struct {
	server *http.Server
	addr   url.URL // "http://127.0.0.1:PORT/gopls/SECRET"
	mux    *http.ServeMux
}

// getWeb returns the web server associated with this
// LSP server, creating it on first request.
func (s *server) getWeb() (*web, error) {
	s.webOnce.Do(func() {
		s.web, s.webErr = s.initWeb()
	})
	return s.web, s.webErr
}

// initWeb starts the local web server through which gopls
// serves package documentation and suchlike.
//
// Clients should use [getWeb].
func (s *server) initWeb() (*web, error) {
	// Use 64 random bits as the base of the URL namespace.
	// This ensures that URLs are unguessable to any local
	// processes that connect to the server, preventing
	// exfiltration of source code.
	//
	// (Note: depending on the LSP client, URLs that are passed to
	// it via showDocument and that result in the opening of a
	// browser tab may be transiently published through the argv
	// array of the open(1) or xdg-open(1) command.)
	token := make([]byte, 8)
	if _, err := rand.Read(token); err != nil {
		return nil, fmt.Errorf("generating secret token: %v", err)
	}

	// Pick any free port.
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		return nil, err
	}

	// -- There should be no early returns after this point. --

	// The root mux is not authenticated.
	rootMux := http.NewServeMux()
	rootMux.HandleFunc("/", func(w http.ResponseWriter, req *http.Request) {
		http.Error(w, "request URI lacks authentication segment", http.StatusUnauthorized)
	})
	rootMux.HandleFunc("/favicon.ico", func(w http.ResponseWriter, req *http.Request) {
		http.Redirect(w, req, "/assets/favicon.ico", http.StatusMovedPermanently)
	})
	rootMux.HandleFunc("/hang", func(w http.ResponseWriter, req *http.Request) {
		// This endpoint hangs until cancelled.
		// It is used by JS to detect server disconnect.
		<-req.Context().Done()
	})

	// Serve assets (JS, PNG, etc) from embedded data,
	// except during local development.
	fs := fs.FS(assets)
	// fs = os.DirFS("/Users/adonovan/w/xtools/gopls/internal/server") // uncomment during development
	rootMux.Handle("/assets/", http.FileServer(http.FS(fs)))

	secret := "/gopls/" + base64.RawURLEncoding.EncodeToString(token)
	webMux := http.NewServeMux()
	rootMux.Handle(secret+"/", withPanicHandler(http.StripPrefix(secret, webMux)))

	webServer := &http.Server{Addr: listener.Addr().String(), Handler: rootMux}
	go func() {
		// This should run until LSP Shutdown, at which point
		// it will return ErrServerClosed. Any other error
		// means it failed to start.
		if err := webServer.Serve(listener); err != nil {
			if err != http.ErrServerClosed {
				log.Print(err)
			}
		}
	}()

	web := &web{
		server: webServer,
		addr:   url.URL{Scheme: "http", Host: webServer.Addr, Path: secret},
		mux:    webMux,
	}

	// The /src handler allows the browser to request that the
	// LSP client editor open a file; see web.SrcURL.
	webMux.HandleFunc("/src", func(w http.ResponseWriter, req *http.Request) {
		if err := req.ParseForm(); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
		uri := protocol.URIFromPath(req.Form.Get("file"))
		line, _ := strconv.Atoi(req.Form.Get("line")) // 1-based
		col, _ := strconv.Atoi(req.Form.Get("col"))   // 1-based UTF-8
		posn := protocol.Position{
			Line:      uint32(line - 1),
			Character: uint32(col - 1), // TODO(adonovan): map to UTF-16
		}
		openClientEditor(req.Context(), s.client, protocol.Location{
			URI:   uri,
			Range: protocol.Range{Start: posn, End: posn},
		}, s.Options())
	})

	// getSnapshot returns the snapshot for the view=... request parameter.
	// On success, the caller must call the snapshot's release function;
	//  callers may assume that req.ParseForm succeeded.
	// On failure, it reports an HTTP error.
	getSnapshot := func(w http.ResponseWriter, req *http.Request) (*cache.Snapshot, func(), bool) {
		if err := req.ParseForm(); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return nil, nil, false
		}
		viewID := req.Form.Get("view")
		if viewID == "" {
			http.Error(w, "no view=... parameter", http.StatusBadRequest)
			return nil, nil, false
		}
		view, err := s.session.View(viewID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusNotFound)
			return nil, nil, false
		}
		snapshot, release, err := view.Snapshot()
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return nil, nil, false
		}
		return snapshot, release, true
	}

	// The /pkg/PATH&view=... handler shows package documentation for PATH.
	webMux.Handle("/pkg/", http.StripPrefix("/pkg/", http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Find package by path.
		pkgPath := metadata.PackagePath(req.URL.Path)
		mps := snapshot.MetadataGraph().ForPackagePath[pkgPath]
		if len(mps) == 0 {
			// TODO(adonovan): what should we do for external test packages?
			http.Error(w, "package not found", http.StatusNotFound)
			return
		}
		found := mps[0]

		// Type-check the package and render its documentation.
		pkgs, err := snapshot.TypeCheck(req.Context(), found.ID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		content, err := golang.PackageDocHTML(snapshot.View().ID(), pkgs[0], web)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		w.Write(content)
	})))

	// The /freesymbols?file=...&range=...&view=... handler shows
	// free symbols referenced by the selection.
	webMux.HandleFunc("/freesymbols", func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Get selection range and type-check.
		loc := protocol.Location{
			URI: protocol.DocumentURI(req.Form.Get("file")),
		}
		if _, err := fmt.Sscanf(req.Form.Get("range"), "%d:%d:%d:%d",
			&loc.Range.Start.Line,
			&loc.Range.Start.Character,
			&loc.Range.End.Line,
			&loc.Range.End.Character,
		); err != nil {
			http.Error(w, "invalid range", http.StatusInternalServerError)
			return
		}
		pkg, pgf, err := golang.NarrowestPackageForFile(req.Context(), snapshot, loc.URI)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		start, end, err := pgf.RangePos(loc.Range)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}

		// Produce report.
		html := golang.FreeSymbolsHTML(snapshot.View().ID(), pkg, pgf, start, end, web)
		w.Write(html)
	})

	// The /assembly?pkg=...&view=...&symbol=... handler shows
	// the assembly of the current function.
	webMux.HandleFunc("/assembly", func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Get other parameters.
		var (
			pkgID  = metadata.PackageID(req.Form.Get("pkg"))
			symbol = req.Form.Get("symbol")
		)
		if pkgID == "" || symbol == "" {
			http.Error(w, "/assembly requires pkg, symbol", http.StatusBadRequest)
			return
		}

		ctx := req.Context()
		pkgs, err := snapshot.TypeCheck(ctx, pkgID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		pkg := pkgs[0]

		// Produce report.
		golang.AssemblyHTML(ctx, snapshot, w, pkg, symbol, web)
	})

	// The /splitpkg?pkg=...&view=... handler shows
	// the "split package" tool (HTML) for the specified package/view.
	webMux.HandleFunc("/splitpkg", func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Get metadata for pkg.
		pkgID := metadata.PackageID(req.Form.Get("pkg"))
		if pkgID == "" {
			http.Error(w, "/splitpkg requires pkg", http.StatusBadRequest)
			return
		}
		mp := snapshot.Metadata(pkgID)
		if mp == nil {
			http.Error(w, "no such package: "+string(pkgID), http.StatusInternalServerError)
			return
		}

		w.Write(splitpkg.HTML(mp.PkgPath))
	})

	// The /splitpkg-json?pkg=...&view=... handler returns the symbol reference graph.
	webMux.HandleFunc("/splitpkg-json", func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Get type information for pkg.
		pkgID := metadata.PackageID(req.Form.Get("pkg"))
		if pkgID == "" {
			http.Error(w, "/splitpkg-json requires pkg", http.StatusBadRequest)
			return
		}
		pkgs, err := snapshot.TypeCheck(req.Context(), pkgID)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		pkg := pkgs[0]

		data, err := splitpkg.JSON(pkg, web)
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		w.Write(data)
	})

	// The /splitpkg-components?pkg=...&view=... handler updates the components mapping.
	// for the specified package, causing it to be saved persistently, and
	// returned by future /splitpkg-json queries.
	webMux.HandleFunc("/splitpkg-components", func(w http.ResponseWriter, req *http.Request) {
		snapshot, release, ok := getSnapshot(w, req)
		if !ok {
			return
		}
		defer release()

		// Get metadata for pkg.
		pkgID := metadata.PackageID(req.Form.Get("pkg"))
		if pkgID == "" {
			http.Error(w, "/splitpkg-components requires pkg", http.StatusBadRequest)
			return
		}
		mp := snapshot.Metadata(pkgID)
		if mp == nil {
			http.Error(w, "no such package: "+string(pkgID), http.StatusInternalServerError)
			return
		}

		data, err := io.ReadAll(req.Body)
		if err != nil {
			msg := fmt.Sprintf("reading request body: %v", err)
			http.Error(w, msg, http.StatusBadRequest)
			return
		}

		if err := splitpkg.UpdateComponentsJSON(pkgID, data); err != nil {
			http.Error(w, err.Error(), http.StatusBadRequest)
			return
		}
	})

	return web, nil
}

// assets holds our static web server content.
//
//go:embed assets/*
var assets embed.FS

// SrcURL returns a /src URL that, when visited, causes the client
// editor to open the specified file/line/column (in 1-based UTF-8
// coordinates).
//
// (Rendering may generate hundreds of positions across files of many
// packages, so don't convert to LSP coordinates yet: wait until the
// URL is opened.)
func (w *web) SrcURL(filename string, line, col8 int) protocol.URI {
	query := fmt.Sprintf("file=%s&line=%d&col=%d",
		url.QueryEscape(filename),
		line,
		col8)
	return w.url("src", query, "")
}

// PkgURL returns a /pkg URL for the documentation of the specified package.
// The optional fragment must be of the form "Println" or "Buffer.WriteString".
func (w *web) PkgURL(viewID string, path golang.PackagePath, fragment string) protocol.URI {
	query := "view=" + url.QueryEscape(viewID)
	return w.url("pkg/"+string(path), query, fragment)
}

// freesymbolsURL returns a /freesymbols URL for a report
// on the free symbols referenced within the selection span (loc).
func (w *web) freesymbolsURL(viewID string, loc protocol.Location) protocol.URI {
	query := fmt.Sprintf("file=%s&range=%d:%d:%d:%d&view=%s",
		url.QueryEscape(string(loc.URI)),
		loc.Range.Start.Line,
		loc.Range.Start.Character,
		loc.Range.End.Line,
		loc.Range.End.Character,
		url.QueryEscape(viewID))
	return w.url("freesymbols", query, "")
}

// assemblyURL returns the URL of an assembly listing of the specified function symbol.
func (w *web) assemblyURL(viewID, packageID, symbol string) protocol.URI {
	query := fmt.Sprintf("view=%s&pkg=%s&symbol=%s",
		url.QueryEscape(viewID),
		url.QueryEscape(packageID),
		url.QueryEscape(symbol))
	return w.url("assembly", query, "")
}

// splitpkgURL returns the URL of the "split package" HTML page for the specified package.
func (w *web) splitpkgURL(viewID, packageID string) protocol.URI {
	query := fmt.Sprintf("view=%s&pkg=%s",
		url.QueryEscape(viewID),
		url.QueryEscape(packageID))
	return w.url("splitpkg", query, "")
}

// url returns a URL by joining a relative path, an (encoded) query,
// and an (unencoded) fragment onto the authenticated base URL of the
// web server.
func (w *web) url(path, query, fragment string) protocol.URI {
	url2 := w.addr
	url2.Path = paths.Join(url2.Path, strings.TrimPrefix(path, "/"))
	url2.RawQuery = query
	url2.Fragment = fragment
	return protocol.URI(url2.String())
}

// withPanicHandler wraps an HTTP handler with telemetry-reporting of
// panics that would otherwise be silently recovered by the net/http
// root handler.
func withPanicHandler(h http.Handler) http.HandlerFunc {
	return func(w http.ResponseWriter, req *http.Request) {
		panicked := true
		defer func() {
			if panicked {
				bug.Report("panic in HTTP handler")
			}
		}()
		h.ServeHTTP(w, req)
		panicked = false
	}
}


================================================
FILE: gopls/internal/server/signature_help.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) SignatureHelp(ctx context.Context, params *protocol.SignatureHelpParams) (*protocol.SignatureHelp, error) {
	ctx, done := event.Start(ctx, "server.SignatureHelp", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	if snapshot.FileKind(fh) != file.Go {
		return nil, nil // empty result
	}

	info, err := golang.SignatureHelp(ctx, snapshot, fh, params.Range, params.Context)
	if err != nil {
		// TODO(rfindley): is this correct? Apparently, returning an error from
		// signatureHelp is distracting in some editors, though I haven't confirmed
		// that recently.
		//
		// It's unclear whether we still need to avoid returning this error result.
		event.Error(ctx, "signature help failed", err, label.Position.Of(params.Range.Start), label.Position.Of(params.Range.End))
		return nil, nil
	}
	if info == nil {
		return nil, nil
	}
	return &protocol.SignatureHelp{
		Signatures:      []protocol.SignatureInformation{*info},
		ActiveSignature: 0,
		ActiveParameter: info.ActiveParameter,
	}, nil
}


================================================
FILE: gopls/internal/server/symbols.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/template"
	"golang.org/x/tools/internal/event"
)

func (s *server) DocumentSymbol(ctx context.Context, params *protocol.DocumentSymbolParams) ([]any, error) {
	ctx, done := event.Start(ctx, "server.DocumentSymbol", label.URI.Of(params.TextDocument.URI))
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()

	var docSymbols []protocol.DocumentSymbol
	switch snapshot.FileKind(fh) {
	case file.Tmpl:
		docSymbols, err = template.DocumentSymbols(snapshot, fh)
	case file.Go:
		docSymbols, err = golang.DocumentSymbols(ctx, snapshot, fh)
	default:
		return nil, nil // empty result
	}
	if err != nil {
		event.Error(ctx, "DocumentSymbols failed", err)
		return nil, nil // empty result
	}
	// Convert the symbols to an interface array.
	// TODO: Remove this once the lsp deprecates SymbolInformation.
	symbols := make([]any, len(docSymbols))
	for i, s := range docSymbols {
		if snapshot.Options().HierarchicalDocumentSymbolSupport {
			symbols[i] = s
			continue
		}
		// If the client does not support hierarchical document symbols, then
		// we need to be backwards compatible for now and return SymbolInformation.
		symbols[i] = protocol.SymbolInformation{
			Name:       s.Name,
			Kind:       s.Kind,
			Deprecated: s.Deprecated,
			Location:   params.TextDocument.URI.Location(s.Range),
		}
	}
	return symbols, nil
}


================================================
FILE: gopls/internal/server/text_synchronization.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"path/filepath"
	"strings"
	"sync"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/label"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/xcontext"
)

// ModificationSource identifies the origin of a change.
type ModificationSource int

const (
	// FromDidOpen is from a didOpen notification.
	FromDidOpen = ModificationSource(iota)

	// FromDidChange is from a didChange notification.
	FromDidChange

	// FromDidChangeWatchedFiles is from didChangeWatchedFiles notification.
	FromDidChangeWatchedFiles

	// FromDidSave is from a didSave notification.
	FromDidSave

	// FromDidClose is from a didClose notification.
	FromDidClose

	// FromDidChangeConfiguration is from a didChangeConfiguration notification.
	FromDidChangeConfiguration

	// FromRegenerateCgo refers to file modifications caused by regenerating
	// the cgo sources for the workspace.
	FromRegenerateCgo

	// FromInitialWorkspaceLoad refers to the loading of all packages in the
	// workspace when the view is first created.
	FromInitialWorkspaceLoad

	// FromCheckUpgrades refers to state changes resulting from the CheckUpgrades
	// command, which queries module upgrades.
	FromCheckUpgrades

	// FromResetGoModDiagnostics refers to state changes resulting from the
	// ResetGoModDiagnostics command.
	FromResetGoModDiagnostics

	// FromToggleCompilerOptDetails refers to state changes resulting from toggling
	// a package's compiler optimization details flag.
	FromToggleCompilerOptDetails
)

func (m ModificationSource) String() string {
	switch m {
	case FromDidOpen:
		return "opened files"
	case FromDidChange:
		return "changed files"
	case FromDidChangeWatchedFiles:
		return "files changed on disk"
	case FromDidSave:
		return "saved files"
	case FromDidClose:
		return "close files"
	case FromRegenerateCgo:
		return "regenerate cgo"
	case FromInitialWorkspaceLoad:
		return "initial workspace load"
	case FromCheckUpgrades:
		return "from check upgrades"
	case FromResetGoModDiagnostics:
		return "from resetting go.mod diagnostics"
	default:
		return "unknown file modification"
	}
}

func (s *server) DidOpen(ctx context.Context, params *protocol.DidOpenTextDocumentParams) error {
	ctx, done := event.Start(ctx, "server.DidOpen", label.URI.Of(params.TextDocument.URI))
	defer done()

	uri := params.TextDocument.URI
	// There may not be any matching view in the current session. If that's
	// the case, try creating a new view based on the opened file path.
	//
	// TODO(golang/go#57979): revisit creating a folder here. We should separate
	// the logic for managing folders from the logic for managing views. But it
	// does make sense to ensure at least one workspace folder the first time a
	// file is opened, and we can't do that inside didModifyFiles because we
	// don't want to request configuration while holding a lock.
	if len(s.session.Views()) == 0 {
		dir := uri.DirPath()
		s.addFolders(ctx, []protocol.WorkspaceFolder{{
			URI:  string(protocol.URIFromPath(dir)),
			Name: filepath.Base(dir),
		}})
	}
	return s.didModifyFiles(ctx, []file.Modification{{
		URI:        uri,
		Action:     file.Open,
		Version:    params.TextDocument.Version,
		Text:       []byte(params.TextDocument.Text),
		LanguageID: params.TextDocument.LanguageID,
	}}, FromDidOpen)
}

func (s *server) DidChange(ctx context.Context, params *protocol.DidChangeTextDocumentParams) error {
	ctx, done := event.Start(ctx, "server.DidChange", label.URI.Of(params.TextDocument.URI))
	defer done()

	uri := params.TextDocument.URI
	text, err := s.changedText(ctx, uri, params.ContentChanges)
	if err != nil {
		return err
	}
	c := file.Modification{
		URI:     uri,
		Action:  file.Change,
		Version: params.TextDocument.Version,
		Text:    text,
	}
	if err := s.didModifyFiles(ctx, []file.Modification{c}, FromDidChange); err != nil {
		return err
	}
	return s.warnAboutModifyingGeneratedFiles(ctx, uri)
}

// warnAboutModifyingGeneratedFiles shows a warning if a user tries to edit a
// generated file for the first time.
func (s *server) warnAboutModifyingGeneratedFiles(ctx context.Context, uri protocol.DocumentURI) error {
	s.changedFilesMu.Lock()
	_, ok := s.changedFiles[uri]
	if !ok {
		s.changedFiles[uri] = struct{}{}
	}
	s.changedFilesMu.Unlock()

	// This file has already been edited before.
	if ok {
		return nil
	}

	// Warn the user that they are editing a generated file, but
	// don't try to stop them: there are often good reasons to do
	// so, such as adding temporary logging, or evaluating changes
	// to the generated code without the trouble of modifying the
	// generator logic (see #73959).
	snapshot, release, err := s.session.SnapshotOf(ctx, uri)
	if err != nil {
		return err
	}
	isGenerated := golang.IsGenerated(ctx, snapshot, uri)
	release()
	if isGenerated {
		msg := fmt.Sprintf("Warning: editing %s, a generated file.", uri.Base())
		showMessage(ctx, s.client, protocol.Warning, msg)
	}
	return nil
}

func (s *server) DidChangeWatchedFiles(ctx context.Context, params *protocol.DidChangeWatchedFilesParams) error {
	ctx, done := event.Start(ctx, "server.DidChangeWatchedFiles")
	defer done()

	var modifications []file.Modification
	for _, change := range params.Changes {
		action := changeTypeToFileAction(change.Type)
		modifications = append(modifications, file.Modification{
			URI:    change.URI,
			Action: action,
			OnDisk: true,
		})
	}
	return s.didModifyFiles(ctx, modifications, FromDidChangeWatchedFiles)
}

func (s *server) DidSave(ctx context.Context, params *protocol.DidSaveTextDocumentParams) error {
	ctx, done := event.Start(ctx, "server.DidSave", label.URI.Of(params.TextDocument.URI))
	defer done()

	c := file.Modification{
		URI:    params.TextDocument.URI,
		Action: file.Save,
	}
	if params.Text != nil {
		c.Text = []byte(*params.Text)
	}
	return s.didModifyFiles(ctx, []file.Modification{c}, FromDidSave)
}

func (s *server) DidClose(ctx context.Context, params *protocol.DidCloseTextDocumentParams) error {
	ctx, done := event.Start(ctx, "server.DidClose", label.URI.Of(params.TextDocument.URI))
	defer done()

	return s.didModifyFiles(ctx, []file.Modification{
		{
			URI:     params.TextDocument.URI,
			Action:  file.Close,
			Version: -1,
			Text:    nil,
		},
	}, FromDidClose)
}

func (s *server) didModifyFiles(ctx context.Context, modifications []file.Modification, cause ModificationSource) error {
	// wg guards two conditions:
	//  1. didModifyFiles is complete
	//  2. the goroutine diagnosing changes on behalf of didModifyFiles is
	//     complete, if it was started
	//
	// Both conditions must be satisfied for the purpose of testing: we don't
	// want to observe the completion of change processing until we have received
	// all diagnostics as well as all server->client notifications done on behalf
	// of this function.
	var wg sync.WaitGroup
	wg.Add(1)
	defer wg.Done()

	if s.Options().VerboseWorkDoneProgress {
		work := s.progress.Start(ctx, DiagnosticWorkTitle(cause), "Calculating file diagnostics...", nil, nil)
		go func() {
			wg.Wait()
			work.End(ctx, "Done.")
		}()
	}

	s.stateMu.Lock()
	if s.state >= serverShutDown {
		// This state check does not prevent races below, and exists only to
		// produce a better error message. The actual race to the cache should be
		// guarded by Session.viewMu.
		s.stateMu.Unlock()
		return errors.New("server is shut down")
	}
	s.stateMu.Unlock()

	// If the set of changes included directories, expand those directories
	// to their files.
	modifications = s.session.ExpandModificationsToDirectories(ctx, modifications)

	s.handleModuleChanges(ctx, modifications, cause)

	viewsToDiagnose, err := s.session.DidModifyFiles(ctx, modifications)
	if err != nil {
		return err
	}

	// golang/go#50267: diagnostics should be re-sent after each change.
	for _, mod := range modifications {
		s.mustPublishDiagnostics(mod.URI)
	}

	modCtx, modID := s.needsDiagnosis(ctx, viewsToDiagnose)

	wg.Go(func() {
		s.diagnoseChangedViews(modCtx, modID, viewsToDiagnose, cause)
	})

	// After any file modifications, we need to update our watched files,
	// in case something changed. Compute the new set of directories to watch,
	// and if it differs from the current set, send updated registrations.
	return s.updateWatchedDirectories(ctx)
}

func (s *server) handleModuleChanges(ctx context.Context, modifications []file.Modification, cause ModificationSource) {
	// If any change in this batch is not a module metadata file, gopls will treat
	// the entire batch as a bulk operation (like a git branch switch). This is to
	// avoid doing expensive dependency checks for every module file in a
	// large change, which is redundant during a full workspace load.
	//
	// This also accounts for "atomic saves" in editors like Vim/Neovim,
	// which may surface as a Delete + Create sequence in the file watcher
	// rather than a single Save event.
	if cause == FromDidChangeWatchedFiles {
		for _, m := range modifications {
			switch m.URI.Base() {
			case "go.mod", "go.sum", "go.work", "go.work.sum":
				// Module metadata file; continue checking.
			default:
				// Batch contains non-module files; skip dependency checks.
				return
			}
		}
	}

	uris := make(map[protocol.DocumentURI]struct{})
	for _, m := range modifications {
		if (m.URI.Base() == "go.mod" || m.URI.Base() == "go.work") && (m.Action == file.Create || m.Action == file.Save) {
			uris[m.URI] = struct{}{}
		}
	}

	for uri := range uris {
		go s.checkDependencyChanges(ctx, uri)
	}
}

// needsDiagnosis records the given views as needing diagnosis, returning the
// context and modification id to use for said diagnosis.
//
// Only the keys of viewsToDiagnose are used; the changed files are irrelevant.
func (s *server) needsDiagnosis(ctx context.Context, viewsToDiagnose map[*cache.View][]protocol.DocumentURI) (context.Context, uint64) {
	s.modificationMu.Lock()
	defer s.modificationMu.Unlock()
	if s.cancelPrevDiagnostics != nil {
		s.cancelPrevDiagnostics()
	}
	modCtx := xcontext.Detach(ctx)
	modCtx, s.cancelPrevDiagnostics = context.WithCancel(modCtx)
	s.lastModificationID++
	modID := s.lastModificationID

	for v := range viewsToDiagnose {
		if needs, ok := s.viewsToDiagnose[v]; !ok || needs < modID {
			s.viewsToDiagnose[v] = modID
		}
	}
	return modCtx, modID
}

// DiagnosticWorkTitle returns the title of the diagnostic work resulting from a
// file change originating from the given cause.
func DiagnosticWorkTitle(cause ModificationSource) string {
	return fmt.Sprintf("diagnosing %v", cause)
}

func (s *server) changedText(ctx context.Context, uri protocol.DocumentURI, changes []protocol.TextDocumentContentChangeEvent) ([]byte, error) {
	if len(changes) == 0 {
		return nil, fmt.Errorf("%w: no content changes provided", jsonrpc2.ErrInternal)
	}

	// Check if the client sent the full content of the file.
	// We accept a full content change even if the server expected incremental changes.
	if len(changes) == 1 && changes[0].Range == nil && changes[0].RangeLength == nil {
		changeFull.Inc()
		return []byte(changes[0].Text), nil
	}
	return s.applyIncrementalChanges(ctx, uri, changes)
}

func (s *server) applyIncrementalChanges(ctx context.Context, uri protocol.DocumentURI, changes []protocol.TextDocumentContentChangeEvent) ([]byte, error) {
	fh, err := s.session.ReadFile(ctx, uri)
	if err != nil {
		return nil, err
	}
	content, err := fh.Content()
	if err != nil {
		return nil, fmt.Errorf("%w: file not found (%v)", jsonrpc2.ErrInternal, err)
	}
	for i, change := range changes {
		// TODO(adonovan): refactor to use diff.Apply, which is robust w.r.t.
		// out-of-order or overlapping changes---and much more efficient.

		// Make sure to update mapper along with the content.
		m := protocol.NewMapper(uri, content)
		if change.Range == nil {
			return nil, fmt.Errorf("%w: unexpected nil range for change", jsonrpc2.ErrInternal)
		}
		start, end, err := m.RangeOffsets(*change.Range)
		if err != nil {
			return nil, err
		}
		if end < start {
			return nil, fmt.Errorf("%w: invalid range for content change", jsonrpc2.ErrInternal)
		}
		var buf bytes.Buffer
		buf.Write(content[:start])
		buf.WriteString(change.Text)
		buf.Write(content[end:])
		content = buf.Bytes()
		if i == 0 { // only look at the first change if there are seversl
			// TODO(pjw): understand multi-change)
			s.checkEfficacy(fh.URI(), fh.Version(), change)
		}
	}
	return content, nil
}

// increment counters if any of the completions look like there were used
func (s *server) checkEfficacy(uri protocol.DocumentURI, version int32, change protocol.TextDocumentContentChangePartial) {
	s.efficacyMu.Lock()
	defer s.efficacyMu.Unlock()
	if s.efficacyURI != uri {
		return
	}
	// gopls increments the version, the test client does not
	if version != s.efficacyVersion && version != s.efficacyVersion+1 {
		return
	}
	// does any change at pos match a proposed completion item?
	for _, item := range s.efficacyItems {
		if item.TextEdit == nil {
			continue
		}
		// CompletionTextEdit may have both insert/replace mode ranges.
		// According to the LSP spec, if an `InsertReplaceEdit` is returned
		// the edit's insert range must be a prefix of the edit's replace range,
		// that means it must be contained and starting at the same position.
		// The efficacy computation uses only the start range, so it is not
		// affected by whether the client applied the suggestion in insert
		// or replace mode. Let's just use the replace mode that was the default
		// in gopls for a while.
		edit, err := protocol.SelectCompletionTextEdit(item, false)
		if err != nil {
			continue
		}
		if edit.Range.Start == change.Range.Start {
			// the change and the proposed completion start at the same
			if (change.RangeLength == nil || *change.RangeLength == 0) && len(change.Text) == 1 {
				// a single character added it does not count as a completion
				continue
			}
			ix := strings.Index(edit.NewText, "$")
			if ix < 0 && strings.HasPrefix(change.Text, edit.NewText) {
				// not a snippet, suggested completion is a prefix of the change
				complUsed.Inc()
				return
			}
			if ix > 1 && strings.HasPrefix(change.Text, edit.NewText[:ix]) {
				// a snippet, suggested completion up to $ marker is a prefix of the change
				complUsed.Inc()
				return
			}
		}
	}
	complUnused.Inc()
}

func changeTypeToFileAction(ct protocol.FileChangeType) file.Action {
	switch ct {
	case protocol.Changed:
		return file.Change
	case protocol.Created:
		return file.Create
	case protocol.Deleted:
		return file.Delete
	}
	return file.UnknownAction
}


================================================
FILE: gopls/internal/server/type_hierarchy.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func (s *server) PrepareTypeHierarchy(ctx context.Context, params *protocol.TypeHierarchyPrepareParams) ([]protocol.TypeHierarchyItem, error) {
	ctx, done := event.Start(ctx, "server.PrepareTypeHierarchy")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.TextDocument.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.PrepareTypeHierarchy(ctx, snapshot, fh, params.Range)
	}
	return nil, fmt.Errorf("unsupported file type: %v", fh)
}

func (s *server) Subtypes(ctx context.Context, params *protocol.TypeHierarchySubtypesParams) ([]protocol.TypeHierarchyItem, error) {
	ctx, done := event.Start(ctx, "server.Subtypes")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.Item.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.Subtypes(ctx, snapshot, fh, params.Item)
	}
	return nil, fmt.Errorf("unsupported file type: %v", fh)
}

func (s *server) Supertypes(ctx context.Context, params *protocol.TypeHierarchySupertypesParams) ([]protocol.TypeHierarchyItem, error) {
	ctx, done := event.Start(ctx, "server.Supertypes")
	defer done()

	fh, snapshot, release, err := s.session.FileOf(ctx, params.Item.URI)
	if err != nil {
		return nil, err
	}
	defer release()
	switch snapshot.FileKind(fh) {
	case file.Go:
		return golang.Supertypes(ctx, snapshot, fh, params.Item)
	}
	return nil, fmt.Errorf("unsupported file type: %v", fh)
}


================================================
FILE: gopls/internal/server/unimplemented.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

// This file defines the LSP server methods that gopls does not currently implement.

import (
	"context"
	"fmt"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/jsonrpc2"
)

func (s *server) ColorPresentation(context.Context, *protocol.ColorPresentationParams) ([]protocol.ColorPresentation, error) {
	return nil, notImplemented("ColorPresentation")
}

func (s *server) Declaration(context.Context, *protocol.DeclarationParams) (*protocol.Or_textDocument_declaration, error) {
	return nil, notImplemented("Declaration")
}

func (s *server) DiagnosticWorkspace(context.Context, *protocol.WorkspaceDiagnosticParams) (*protocol.WorkspaceDiagnosticReport, error) {
	return nil, notImplemented("DiagnosticWorkspace")
}

func (s *server) DidChangeNotebookDocument(context.Context, *protocol.DidChangeNotebookDocumentParams) error {
	return notImplemented("DidChangeNotebookDocument")
}

func (s *server) DidCloseNotebookDocument(context.Context, *protocol.DidCloseNotebookDocumentParams) error {
	return notImplemented("DidCloseNotebookDocument")
}

func (s *server) DidDeleteFiles(context.Context, *protocol.DeleteFilesParams) error {
	return notImplemented("DidDeleteFiles")
}

func (s *server) DidOpenNotebookDocument(context.Context, *protocol.DidOpenNotebookDocumentParams) error {
	return notImplemented("DidOpenNotebookDocument")
}

func (s *server) DidRenameFiles(context.Context, *protocol.RenameFilesParams) error {
	return notImplemented("DidRenameFiles")
}

func (s *server) DidSaveNotebookDocument(context.Context, *protocol.DidSaveNotebookDocumentParams) error {
	return notImplemented("DidSaveNotebookDocument")
}

func (s *server) DocumentColor(context.Context, *protocol.DocumentColorParams) ([]protocol.ColorInformation, error) {
	return nil, notImplemented("DocumentColor")
}

func (s *server) InlineCompletion(context.Context, *protocol.InlineCompletionParams) (*protocol.Or_Result_textDocument_inlineCompletion, error) {
	return nil, notImplemented("InlineCompletion")
}

func (s *server) InlineValue(context.Context, *protocol.InlineValueParams) ([]protocol.InlineValue, error) {
	return nil, notImplemented("InlineValue")
}

func (s *server) InteractiveListEnum(context.Context, *protocol.InteractiveListEnumParams) ([]protocol.FormEnumEntry, error) {
	return nil, notImplemented("InteractiveListEnum")
}

func (s *server) LinkedEditingRange(context.Context, *protocol.LinkedEditingRangeParams) (*protocol.LinkedEditingRanges, error) {
	return nil, notImplemented("LinkedEditingRange")
}

func (s *server) Moniker(context.Context, *protocol.MonikerParams) ([]protocol.Moniker, error) {
	return nil, notImplemented("Moniker")
}

func (s *server) OnTypeFormatting(context.Context, *protocol.DocumentOnTypeFormattingParams) ([]protocol.TextEdit, error) {
	return nil, notImplemented("OnTypeFormatting")
}

func (s *server) Progress(context.Context, *protocol.ProgressParams) error {
	return notImplemented("Progress")
}

func (s *server) RangeFormatting(context.Context, *protocol.DocumentRangeFormattingParams) ([]protocol.TextEdit, error) {
	return nil, notImplemented("RangeFormatting")
}

func (s *server) RangesFormatting(context.Context, *protocol.DocumentRangesFormattingParams) ([]protocol.TextEdit, error) {
	return nil, notImplemented("RangesFormatting")
}

func (s *server) Resolve(context.Context, *protocol.InlayHint) (*protocol.InlayHint, error) {
	return nil, notImplemented("Resolve")
}

func (s *server) ResolveCodeLens(context.Context, *protocol.CodeLens) (*protocol.CodeLens, error) {
	return nil, notImplemented("ResolveCodeLens")
}

func (s *server) ResolveCompletionItem(context.Context, *protocol.CompletionItem) (*protocol.CompletionItem, error) {
	return nil, notImplemented("ResolveCompletionItem")
}

func (s *server) ResolveDocumentLink(context.Context, *protocol.DocumentLink) (*protocol.DocumentLink, error) {
	return nil, notImplemented("ResolveDocumentLink")
}

func (s *server) ResolveWorkspaceSymbol(context.Context, *protocol.WorkspaceSymbol) (*protocol.WorkspaceSymbol, error) {
	return nil, notImplemented("ResolveWorkspaceSymbol")
}

func (s *server) SemanticTokensFullDelta(context.Context, *protocol.SemanticTokensDeltaParams) (any, error) {
	return nil, notImplemented("SemanticTokensFullDelta")
}

func (s *server) SetTrace(context.Context, *protocol.SetTraceParams) error {
	return notImplemented("SetTrace")
}

func (s *server) WillCreateFiles(context.Context, *protocol.CreateFilesParams) (*protocol.WorkspaceEdit, error) {
	return nil, notImplemented("WillCreateFiles")
}

func (s *server) WillDeleteFiles(context.Context, *protocol.DeleteFilesParams) (*protocol.WorkspaceEdit, error) {
	return nil, notImplemented("WillDeleteFiles")
}

func (s *server) WillRenameFiles(context.Context, *protocol.RenameFilesParams) (*protocol.WorkspaceEdit, error) {
	return nil, notImplemented("WillRenameFiles")
}

func (s *server) WillSave(context.Context, *protocol.WillSaveTextDocumentParams) error {
	return notImplemented("WillSave")
}

func (s *server) WillSaveWaitUntil(context.Context, *protocol.WillSaveTextDocumentParams) ([]protocol.TextEdit, error) {
	return nil, notImplemented("WillSaveWaitUntil")
}

func (s *server) TextDocumentContent(context.Context, *protocol.TextDocumentContentParams) (*protocol.TextDocumentContentResult, error) {
	return nil, notImplemented("TextDocumentContent")
}

func notImplemented(method string) error {
	return fmt.Errorf("%w: %q not yet implemented", jsonrpc2.ErrMethodNotFound, method)
}


================================================
FILE: gopls/internal/server/vulncheck_prompt.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"bytes"
	"context"
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"maps"
	"os"
	"path/filepath"
	"slices"
	"sort"
	"strings"

	"golang.org/x/mod/modfile"
	"golang.org/x/mod/semver"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/xcontext"
)

const (
	// dependencyHashKind is the kind for the dependency hash in the filecache.
	dependencyHashKind = "dephash"
	maxVulnsToShow     = 10
)

type vulncheckAction string

const (
	vulncheckActionYes    vulncheckAction = "Yes"
	vulncheckActionNo     vulncheckAction = "No"
	vulncheckActionAlways vulncheckAction = "Always"
	vulncheckActionNever  vulncheckAction = "Never"
	vulncheckActionEmpty  vulncheckAction = ""
)

type vulnupgradeAction string

const (
	vulnupgradeActionUpgradeAll vulnupgradeAction = "Upgrade All"
	vulnupgradeActionIgnore     vulnupgradeAction = "Ignore"
	vulnupgradeActionEmpty      vulnupgradeAction = ""
)

// computeGoModHash computes the SHA256 hash of the go.mod file's dependencies.
// It only considers the Require, Exclude, and Replace directives and ignores
// other parts of the file.
func computeGoModHash(file *modfile.File) (string, error) {
	h := sha256.New()
	for _, req := range file.Require {
		if _, err := h.Write([]byte(req.Mod.Path + "\x00" + req.Mod.Version)); err != nil {
			return "", err
		}
	}
	for _, exc := range file.Exclude {
		if _, err := h.Write([]byte(exc.Mod.Path + "\x00" + exc.Mod.Version)); err != nil {
			return "", err
		}
	}
	for _, rep := range file.Replace {
		if _, err := h.Write([]byte(rep.Old.Path + "\x00" + rep.Old.Version + "\x00" + rep.New.Path + "\x00" + rep.New.Version)); err != nil {
			return "", err
		}
	}
	return hex.EncodeToString(h.Sum(nil)), nil
}

// computeGoWorkHash computes the SHA256 hash of the go.work file's dependencies.
// It only considers the Use and Replace directives and ignores other parts of
// the file.
func computeGoWorkHash(file *modfile.WorkFile) (string, error) {
	h := sha256.New()
	for _, use := range file.Use {
		if _, err := h.Write([]byte(use.Path + "\x00")); err != nil {
			return "", err
		}
	}
	for _, rep := range file.Replace {
		if _, err := h.Write([]byte(rep.Old.Path + "\x00" + rep.Old.Version + "\x00" + rep.New.Path + "\x00" + rep.New.Version)); err != nil {
			return "", err
		}
	}
	return hex.EncodeToString(h.Sum(nil)), nil
}

func getDependencyHashes(uri protocol.DocumentURI) (contentHash string, pathHash [32]byte, err error) {
	content, err := os.ReadFile(uri.Path())
	if err != nil {
		return "", [32]byte{}, err
	}
	filename := filepath.Base(uri.Path())
	switch filename {
	case "go.mod":
		modFile, err := modfile.Parse(filename, content, nil)
		if err != nil {
			return "", [32]byte{}, err
		}
		contentHash, err = computeGoModHash(modFile)
		if err != nil {
			return "", [32]byte{}, err
		}
	case "go.work":
		workFile, err := modfile.ParseWork(filename, content, nil)
		if err != nil {
			return "", [32]byte{}, err
		}
		contentHash, err = computeGoWorkHash(workFile)
		if err != nil {
			return "", [32]byte{}, err
		}
	default:
		return "", [32]byte{}, fmt.Errorf("unsupported file: %s", filename)
	}
	pathHash = sha256.Sum256([]byte(uri.Path()))
	return contentHash, pathHash, nil
}

func (s *server) checkDependencyChanges(ctx context.Context, uri protocol.DocumentURI) {
	if s.Options().Vulncheck != settings.ModeVulncheckPrompt {
		return
	}
	ctx, done := event.Start(ctx, "server.checkDependencyChanges")
	defer done()

	newHash, pathHash, err := getDependencyHashes(uri)
	if err != nil {
		event.Error(ctx, "getting dependency hashes failed", err)
		return
	}

	oldHashBytes, err := filecache.Get(dependencyHashKind, pathHash)
	if err != nil && err != filecache.ErrNotFound {
		event.Error(ctx, "reading old dependency hash from filecache failed", err)
		return
	}
	oldHash := string(oldHashBytes)

	if oldHash != newHash {
		fileLink := fmt.Sprintf("[%s](%s)", uri.Path(), string(uri))
		govulncheckLink := "[govulncheck](https://pkg.go.dev/golang.org/x/vuln/cmd/govulncheck)"
		message := fmt.Sprintf("Dependencies have changed in %s, would you like to run %s to check for vulnerabilities?", fileLink, govulncheckLink)

		action, err := getVulncheckPreference()
		if err != nil {
			event.Error(ctx, "reading vulncheck preference failed", err)
		}

		switch action {
		case vulncheckActionAlways:
			go s.handleVulncheck(ctx, uri)
		case vulncheckActionNever:
			return
		case vulncheckActionEmpty:
			// no previous preference stored, prompt the user.
			fallthrough
		default:
			// invalid value, clear preference and prompt the user again.
			choice, err := showMessageRequest(ctx, s.client, protocol.Info, message, string(vulncheckActionYes), string(vulncheckActionNo), string(vulncheckActionAlways), string(vulncheckActionNever))
			if err != nil {
				event.Error(ctx, "showing dependency changed notification failed", err)
				return
			}
			action = vulncheckAction(choice)
			recordVulncheckAction(action)
			if action == vulncheckActionAlways || action == vulncheckActionNever {
				if err := setVulncheckPreference(action); err != nil {
					event.Error(ctx, "writing vulncheck preference failed", err)
					showMessage(ctx, s.client, protocol.Error, fmt.Sprintf("Failed to save vulncheck preference: %v", err))
				}
			}
			if action == vulncheckActionYes || action == vulncheckActionAlways {
				go s.handleVulncheck(ctx, uri)
			}
			if action == vulncheckActionEmpty {
				// No user input gathered from prompt.
				return
			}
		}

		if err := filecache.Set(dependencyHashKind, pathHash, []byte(newHash)); err != nil {
			event.Error(ctx, "writing new dependency hash to filecache failed", err)
			return
		}
	}
}

func recordVulncheckAction(action vulncheckAction) {
	switch action {
	case vulncheckActionYes:
		countVulncheckPromptYes.Inc()
	case vulncheckActionNo:
		countVulncheckPromptNo.Inc()
	case vulncheckActionAlways:
		countVulncheckPromptAlways.Inc()
	case vulncheckActionNever:
		countVulncheckPromptNever.Inc()
	}
}

func recordVulncheckupgradeAction(action vulnupgradeAction) {
	switch action {
	case vulnupgradeActionUpgradeAll:
		countVulncheckUpgradeAll.Inc()
	case vulnupgradeActionIgnore:
		countVulncheckUpgradeIgnore.Inc()
	}
}

func (s *server) handleVulncheck(ctx context.Context, uri protocol.DocumentURI) {
	_, snapshot, release, err := s.session.FileOf(ctx, uri)
	if err != nil {
		event.Error(ctx, "getting file snapshot failed", err)
		return
	}
	defer release()
	ctx = xcontext.Detach(ctx)

	work := s.progress.Start(ctx, GoVulncheckCommandTitle, "Running govulncheck...", nil, nil)
	defer work.End(ctx, "Done.")
	workDoneWriter := progress.NewWorkDoneWriter(ctx, work)
	result, err := s.runVulncheck(ctx, snapshot, uri, "./...", workDoneWriter)
	if err != nil {
		event.Error(ctx, "govulncheck failed", err)
		showMessage(ctx, s.client, protocol.Error, fmt.Sprintf("govulncheck failed: %v", err))
		return
	}

	affecting, stdLibVulns, modulesToUpgrade := computeModulesToUpgrade(result.Findings)
	numStdLib := len(stdLibVulns)
	if len(affecting) == 0 && numStdLib == 0 {
		showMessage(ctx, s.client, protocol.Info, "No vulnerabilities found.")
		return
	}

	affectingOSVs := slices.Sorted(maps.Keys(affecting))
	sort.Strings(affectingOSVs)

	var b strings.Builder
	fmt.Fprintf(&b, "Found %d actionable vulnerabilities and %d standard library vulnerabilities affecting your dependencies:\n\n", len(affectingOSVs), numStdLib)

	for i, id := range affectingOSVs {
		if i >= maxVulnsToShow {
			break
		}
		cveURL := fmt.Sprintf("https://pkg.go.dev/vuln/%s", id)
		if s.Options().LinkifyShowMessage {
			fmt.Fprintf(&b, "Vulnerability #%d: [%s](%s)", i+1, id, cveURL)
		} else {
			fmt.Fprintf(&b, "Vulnerability #%d: %s (%s)", i+1, id, cveURL)
		}
		if i < len(affectingOSVs)-1 && i < maxVulnsToShow-1 {
			b.WriteString(", ")
		}
	}
	if len(affectingOSVs) > maxVulnsToShow {
		fmt.Fprintf(&b, "\n\n...and %d more.", len(affectingOSVs)-maxVulnsToShow)
	}

	if numStdLib > 0 {
		if b.Len() > 0 {
			b.WriteString("\n\n")
		}
		b.WriteString("Upgrading your Go version may address vulnerabilities in the standard library.")
	}

	actions := []string{string(vulnupgradeActionIgnore)}
	if len(modulesToUpgrade) > 0 {
		actions = append([]string{string(vulnupgradeActionUpgradeAll)}, actions...)
	}

	action, err := showMessageRequest(ctx, s.client, protocol.Warning, b.String(), actions...)
	if err != nil {
		event.Error(ctx, "vulncheck remediation failed", err)
		return
	}
	upgradeAction := vulnupgradeAction(action)
	recordVulncheckupgradeAction(upgradeAction)

	if upgradeAction == vulnupgradeActionUpgradeAll {
		if err := s.upgradeModules(ctx, snapshot, uri, modulesToUpgrade); err != nil {
			event.Error(ctx, "upgrading modules failed", err)
		}
	}
}

func computeModulesToUpgrade(findings []*govulncheck.Finding) (affecting map[string]bool, stdLibVulns map[string]bool, modulesToUpgrade map[string]string) {
	affecting = make(map[string]bool)
	stdLibVulns = make(map[string]bool)
	modulesToUpgrade = make(map[string]string)

	for _, f := range findings {
		if len(f.Trace) == 0 {
			continue
		}
		mod := f.Trace[0].Module
		// An empty module path or "stdlib" indicates a standard library package.
		// These vulnerabilities cannot be remediated via module upgrades and
		// instead require updating the Go toolchain.
		if mod == "stdlib" || mod == "" {
			stdLibVulns[f.OSV] = true
		} else {
			affecting[f.OSV] = true
			if f.FixedVersion != "" {
				current, ok := modulesToUpgrade[mod]
				if !ok || current == "latest" || semver.Compare(f.FixedVersion, current) > 0 {
					modulesToUpgrade[mod] = f.FixedVersion
				}
			} else if _, ok := modulesToUpgrade[mod]; !ok {
				modulesToUpgrade[mod] = "latest"
			}
		}
	}
	return affecting, stdLibVulns, modulesToUpgrade
}

func (s *server) upgradeModules(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, modulesToUpgrade map[string]string) error {
	if err := s.runGoGet(ctx, snapshot, uri, modulesToUpgrade); err != nil {
		return err
	}
	if err := s.runGoModTidy(ctx, snapshot, uri); err != nil {
		return err
	}

	var (
		upgradedStrs []string
		upgrades     []string
	)
	for module, version := range modulesToUpgrade {
		upgrades = append(upgrades, module+"@"+version)
		upgradedStrs = append(upgradedStrs, fmt.Sprintf("%s to %s", module, version))
	}
	sort.Strings(upgradedStrs)

	msg := fmt.Sprintf("Successfully upgraded vulnerable modules:\n %s", strings.Join(upgradedStrs, ",\n "))
	showMessage(ctx, s.client, protocol.Info, msg)
	if hash, pathHash, err := getDependencyHashes(uri); err == nil {
		if err := filecache.Set(dependencyHashKind, pathHash, []byte(hash)); err != nil {
			event.Error(ctx, "failed to update dependency hash after upgrade", err)
		}
	} else {
		event.Error(ctx, "failed to get dependency hash after upgrade", err)
	}
	return nil
}

func (s *server) runGoGet(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, modulesToUpgrade map[string]string) error {
	work := s.progress.Start(ctx, "Upgrading Modules", "Running go get...", nil, nil)
	defer work.End(ctx, "Done.")

	var upgrades []string
	for module, version := range modulesToUpgrade {
		upgrades = append(upgrades, module+"@"+version)
	}

	if err := runGoCommand(ctx, snapshot, uri, "get", upgrades); err != nil {
		msg := fmt.Sprintf("Failed to upgrade modules: %v", err)
		showMessage(ctx, s.client, protocol.Error, msg)
		return err
	}
	return nil
}

func (s *server) runGoModTidy(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI) error {
	work := s.progress.Start(ctx, "Upgrading Modules", "Running go mod tidy...", nil, nil)
	defer work.End(ctx, "Done.")

	if err := runGoCommand(ctx, snapshot, uri, "mod", []string{"tidy"}); err != nil {
		event.Error(ctx, "go mod tidy failed", err)
		showMessage(ctx, s.client, protocol.Error, fmt.Sprintf("go mod tidy failed: %v", err))
		return err
	}
	return nil
}

func runGoCommand(ctx context.Context, snapshot *cache.Snapshot, uri protocol.DocumentURI, verb string, args []string) error {
	dir := uri.DirPath()
	inv, cleanup, err := snapshot.GoCommandInvocation(cache.NetworkOK, dir, verb, args)
	if err != nil {
		return err
	}
	defer cleanup()
	var stdout, stderr bytes.Buffer
	if err := snapshot.View().GoCommandRunner().RunPiped(ctx, *inv, &stdout, &stderr); err != nil {
		return fmt.Errorf("go %s %s failed: %v\n-- stdout --\n%s\n-- stderr --\n%s", verb, strings.Join(args, " "), err, stdout.String(), stderr.String())
	}
	return nil
}

type vulncheckConfig struct {
	VulncheckMode string `json:"vulncheck"`
}

func getVulncheckPreference() (vulncheckAction, error) {
	configDir, err := os.UserConfigDir()
	if err != nil {
		return "", err
	}
	path := filepath.Join(configDir, "gopls", "vulncheck", "settings.json")
	content, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return "", nil
		}
		return "", err
	}
	var config vulncheckConfig
	if err := json.Unmarshal(content, &config); err != nil {
		return "", err
	}
	return vulncheckAction(config.VulncheckMode), nil
}

func setVulncheckPreference(preference vulncheckAction) error {
	configDir, err := os.UserConfigDir()
	if err != nil {
		return err
	}
	goplsDir := filepath.Join(configDir, "gopls", "vulncheck")
	if err := os.MkdirAll(goplsDir, 0755); err != nil {
		return err
	}
	path := filepath.Join(goplsDir, "settings.json")
	config := vulncheckConfig{VulncheckMode: string(preference)}
	content, err := json.Marshal(config)
	if err != nil {
		return err
	}
	return os.WriteFile(path, content, 0644)
}


================================================
FILE: gopls/internal/server/vulncheck_prompt_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"crypto/sha256"
	"encoding/hex"
	"os"
	"path/filepath"
	"runtime"
	"testing"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/progress"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/testenv"
)

func TestComputeGoModHash(t *testing.T) {
	tests := []struct {
		name    string
		content string
		want    string
		wantErr bool
	}{
		{
			name:    "empty file",
			content: "module example.com",
			want:    "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", // sha256 of empty string
		},
		{
			name: "with require",
			content: `
			module example.com
			require (
				golang.org/x/tools v0.1.0
				golang.org/x/vuln v0.2.0
			)
			`,
			want: func() string {
				h := sha256.New()
				h.Write([]byte("golang.org/x/tools\x00v0.1.0"))
				h.Write([]byte("golang.org/x/vuln\x00v0.2.0"))
				return hex.EncodeToString(h.Sum(nil))
			}(),
		},
		{
			name: "with exclude",
			content: `
			module example.com
			exclude (
				golang.org/x/tools v0.1.0
			)
			`,
			want: func() string {
				h := sha256.New()
				h.Write([]byte("golang.org/x/tools\x00v0.1.0"))
				return hex.EncodeToString(h.Sum(nil))
			}(),
		},
		{
			name: "with replace",
			content: `
			module example.com
			replace (
				golang.org/x/tools v0.1.0 => golang.org/x/tools v0.2.0
			)
			`,
			want: func() string {
				h := sha256.New()
				h.Write([]byte("golang.org/x/tools\x00v0.1.0\x00golang.org/x/tools\x00v0.2.0"))
				return hex.EncodeToString(h.Sum(nil))
			}(),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			modFile, err := modfile.Parse("go.mod", []byte(tt.content), nil)
			if err != nil {
				t.Fatal(err)
			}
			got, err := computeGoModHash(modFile)
			if (err != nil) != tt.wantErr {
				t.Errorf("computeGoModHash() error = %v, wantErr %v", err, tt.wantErr)
				return
			}
			if got != tt.want {
				t.Errorf("computeGoModHash() = %v, want %v", got, tt.want)
			}
		})
	}
}

func TestComputeGoWorkHash(t *testing.T) {
	tests := []struct {
		name    string
		content string
		want    string
		wantErr bool
	}{
		{
			name:    "empty file",
			content: "go 1.25",
			want:    "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855", // sha256 of empty string
		},
		{
			name: "with use",
			content: `
			go 1.25
			use (
				./foo
				./bar
			)
			`,
			want: func() string {
				h := sha256.New()
				h.Write([]byte("./foo\x00"))
				h.Write([]byte("./bar\x00"))
				return hex.EncodeToString(h.Sum(nil))
			}(),
		},
		{
			name: "with replace",
			content: `
			go 1.25
			replace golang.org/x/tools v0.1.0 => ./tools
			`,
			want: func() string {
				h := sha256.New()
				h.Write([]byte("golang.org/x/tools\x00v0.1.0\x00./tools\x00"))
				return hex.EncodeToString(h.Sum(nil))
			}(),
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			workFile, err := modfile.ParseWork("go.work", []byte(tt.content), nil)
			if err != nil {
				t.Fatal(err)
			}
			got, err := computeGoWorkHash(workFile)
			if (err != nil) != tt.wantErr {
				t.Errorf("computeGoWorkHash() error = %v, wantErr %v", err, tt.wantErr)
				return
			}
			if got != tt.want {
				t.Errorf("computeGoWorkHash() = %v, want %v", got, tt.want)
			}
		})
	}
}

type mockClient struct {
	protocol.Client
	showMessageRequest func(context.Context, *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error)
}

func (c *mockClient) ShowMessageRequest(ctx context.Context, params *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error) {
	if c.showMessageRequest != nil {
		return c.showMessageRequest(ctx, params)
	}
	return nil, nil
}

func (c *mockClient) ShowMessage(ctx context.Context, params *protocol.ShowMessageParams) error {
	return nil
}

func (c *mockClient) Close() error {
	return nil
}

func TestCheckDependencyChanges(t *testing.T) {
	testenv.NeedsExec(t)
	const (
		yes    = "Yes"
		no     = "No"
		always = "Always"
		never  = "Never"
	)

	tests := []struct {
		name            string
		filename        string
		vulncheckMode   settings.VulncheckMode
		oldContent      string
		newContent      string
		userAction      string
		wantPrompt      bool
		wantHashUpdated bool
	}{
		{
			name:          "go.mod: vulncheck disabled",
			filename:      "go.mod",
			vulncheckMode: settings.ModeVulncheckOff,
			oldContent:    "module example.com",
			newContent: `
			module example.com
			require golang.org/x/tools v0.1.0
			`,
			wantPrompt: false,
		},
		{
			name:          "go.mod: no changes",
			filename:      "go.mod",
			vulncheckMode: settings.ModeVulncheckPrompt,
			oldContent:    "module example.com",
			newContent:    "module example.com",
			wantPrompt:    false,
		},
		{
			name:          "go.mod: user says yes",
			filename:      "go.mod",
			vulncheckMode: settings.ModeVulncheckPrompt,
			oldContent:    "module example.com",
			newContent: `
			module example.com
			require golang.org/x/tools v0.1.0
			`,
			userAction:      yes,
			wantPrompt:      true,
			wantHashUpdated: true,
		},
		{
			name:          "go.work: user says yes",
			filename:      "go.work",
			vulncheckMode: settings.ModeVulncheckPrompt,
			oldContent:    "go 1.25",
			newContent: `
			go 1.25
			use ./foo
			`,
			userAction:      yes,
			wantPrompt:      true,
			wantHashUpdated: true,
		},
		{
			name:          "go.work: no changes",
			filename:      "go.work",
			vulncheckMode: settings.ModeVulncheckPrompt,
			oldContent:    "go 1.25\nuse ./foo",
			newContent:    "go 1.25\nuse ./foo",
			wantPrompt:    false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Cleanup(func() {
				configDir, err := os.UserConfigDir()
				if err != nil {
					t.Fatalf("os.UserConfigDir() failed: %v", err)
				}
				if err := os.RemoveAll(filepath.Join(configDir, "gopls")); err != nil && !os.IsNotExist(err) {
					t.Fatalf("failed to clear user config: %v", err)
				}
			})
			t.Setenv("HOME", t.TempDir())
			ctx := context.Background()
			var promptShown bool
			client := &mockClient{
				showMessageRequest: func(ctx context.Context, params *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error) {
					promptShown = true
					if tt.userAction == "" {
						return nil, nil
					}
					return &protocol.MessageActionItem{Title: tt.userAction}, nil
				},
			}
			s := &server{
				client:   client,
				session:  cache.NewSession(ctx, cache.New(nil)),
				progress: progress.NewTracker(client),
				options: &settings.Options{
					UserOptions: settings.UserOptions{
						UIOptions: settings.UIOptions{
							DiagnosticOptions: settings.DiagnosticOptions{
								Vulncheck: tt.vulncheckMode,
							},
						},
					},
				},
			}
			dir := t.TempDir()
			filePath := filepath.Join(dir, tt.filename)
			if err := os.WriteFile(filePath, []byte(tt.oldContent), 0644); err != nil {
				t.Fatal(err)
			}
			uri := protocol.URIFromPath(filePath)

			// Set the initial hash in the cache.
			oldHash, _, err := getDependencyHashes(uri)
			if err != nil {
				t.Fatal(err)
			}
			pathHash := sha256.Sum256([]byte(uri.Path()))
			if err := filecache.Set(dependencyHashKind, pathHash, []byte(oldHash)); err != nil {
				t.Fatal(err)
			}

			// Simulate the file change.
			if err := os.WriteFile(filePath, []byte(tt.newContent), 0644); err != nil {
				t.Fatal(err)
			}

			s.checkDependencyChanges(ctx, uri)

			if promptShown != tt.wantPrompt {
				t.Errorf("promptShown = %v, want %v", promptShown, tt.wantPrompt)
			}

			// Check if the hash was updated.
			newHash, _, err := getDependencyHashes(uri)
			if err != nil {
				t.Fatal(err)
			}

			cachedHashBytes, err := filecache.Get(dependencyHashKind, pathHash)
			if err != nil && err != filecache.ErrNotFound {
				t.Fatal(err)
			}
			cachedHash := string(cachedHashBytes)

			if tt.wantHashUpdated {
				if cachedHash != newHash {
					t.Errorf("hash was not updated in cache")
				}
			} else {
				if cachedHash == newHash && oldHash != newHash {
					t.Errorf("hash was updated in cache, but should not have been")
				}
			}
		})
	}
}

func TestVulncheckPreference(t *testing.T) {
	if runtime.GOARCH == "wasm" {
		t.Skip("test not supported in wasm")
	}
	t.Cleanup(func() {
		configDir, err := os.UserConfigDir()
		if err != nil {
			t.Fatalf("os.UserConfigDir() failed: %v", err)
		}
		if err := os.RemoveAll(filepath.Join(configDir, "gopls")); err != nil && !os.IsNotExist(err) {
			t.Fatalf("failed to clear user config: %v", err)
		}
	})
	t.Setenv("HOME", t.TempDir())

	pref, err := getVulncheckPreference()
	if err != nil {
		t.Fatalf("getVulncheckPreference() failed: %v", err)
	}
	if pref != "" {
		t.Errorf("got %q, want empty string", pref)
	}

	want := vulncheckActionAlways
	if err := setVulncheckPreference(want); err != nil {
		t.Fatalf("setVulncheckPreference() failed: %v", err)
	}

	got, err := getVulncheckPreference()
	if err != nil {
		t.Fatalf("getVulncheckPreference() failed: %v", err)
	}

	if got != want {
		t.Errorf("got %q, want %q", got, want)
	}
}


================================================
FILE: gopls/internal/server/workspace.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"
	"fmt"
	"reflect"
	"strings"
	"sync"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/golang/completion"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/internal/event"
)

func (s *server) DidChangeWorkspaceFolders(ctx context.Context, params *protocol.DidChangeWorkspaceFoldersParams) error {
	for _, folder := range params.Event.Removed {
		if !strings.HasPrefix(folder.URI, "file://") {
			// Some clients that support virtual file systems may send workspace change messages
			// about workspace folders in the virtual file systems. addFolders must not add
			// those folders, so they don't need to be removed either.
			continue
		}
		dir, err := protocol.ParseDocumentURI(folder.URI)
		if err != nil {
			return fmt.Errorf("invalid folder %q: %v", folder.URI, err)
		}
		if !s.session.RemoveView(ctx, dir) {
			return fmt.Errorf("view %q for %v not found", folder.Name, folder.URI)
		}
	}
	s.addFolders(ctx, params.Event.Added)
	return nil
}

// addView returns a Snapshot and a release function that must be
// called when it is no longer needed.
func (s *server) addView(ctx context.Context, name string, dir protocol.DocumentURI) (*cache.Snapshot, func(), error) {
	s.stateMu.Lock()
	state := s.state
	s.stateMu.Unlock()
	if state < serverInitialized {
		return nil, nil, fmt.Errorf("addView called before server initialized")
	}
	opts, err := s.fetchFolderOptions(ctx, dir)
	if err != nil {
		return nil, nil, err
	}
	folder, err := s.newFolder(ctx, dir, name, opts)
	if err != nil {
		return nil, nil, err
	}
	_, snapshot, release, err := s.session.NewView(ctx, folder)
	return snapshot, release, err
}

func (s *server) DidChangeConfiguration(ctx context.Context, _ *protocol.DidChangeConfigurationParams) error {
	ctx, done := event.Start(ctx, "server.DidChangeConfiguration")
	defer done()

	var wg sync.WaitGroup
	wg.Add(1)
	defer wg.Done()
	if s.Options().VerboseWorkDoneProgress {
		work := s.progress.Start(ctx, DiagnosticWorkTitle(FromDidChangeConfiguration), "Calculating diagnostics...", nil, nil)
		go func() {
			wg.Wait()
			work.End(ctx, "Done.")
		}()
	}

	// Apply any changes to the session-level settings.
	options, err := s.fetchFolderOptions(ctx, "")
	if err != nil {
		return err
	}
	s.SetOptions(options)

	// Collect options for all workspace folders.
	// If none have changed, this is a no op.
	folderOpts := make(map[protocol.DocumentURI]*settings.Options)
	changed := false
	// The set of views is implicitly guarded by the fact that gopls processes
	// didChange notifications synchronously.
	//
	// TODO(rfindley): investigate this assumption: perhaps we should hold viewMu
	// here.
	views := s.session.Views()
	for _, view := range views {
		folder := view.Folder()
		if folderOpts[folder.Dir] != nil {
			continue
		}
		opts, err := s.fetchFolderOptions(ctx, folder.Dir)
		if err != nil {
			return err
		}

		if !reflect.DeepEqual(folder.Options, opts) {
			changed = true
		}
		folderOpts[folder.Dir] = opts
	}
	if !changed {
		return nil
	}

	var newFolders []*cache.Folder
	for _, view := range views {
		folder := view.Folder()
		opts := folderOpts[folder.Dir]
		newFolder, err := s.newFolder(ctx, folder.Dir, folder.Name, opts)
		if err != nil {
			return err
		}
		newFolders = append(newFolders, newFolder)
	}
	s.session.UpdateFolders(ctx, newFolders) // ignore error

	// The view set may have been updated above.
	viewsToDiagnose := make(map[*cache.View][]protocol.DocumentURI)
	for _, view := range s.session.Views() {
		viewsToDiagnose[view] = nil
	}

	modCtx, modID := s.needsDiagnosis(ctx, viewsToDiagnose)
	wg.Go(func() {
		s.diagnoseChangedViews(modCtx, modID, viewsToDiagnose, FromDidChangeConfiguration)
	})

	// An options change may have affected the detected Go version.
	s.checkViewGoVersions()

	if options.MaxFileCacheBytes > 0 {
		filecache.SetBudget(options.MaxFileCacheBytes)
	}

	return nil
}

func (s *server) DidCreateFiles(ctx context.Context, params *protocol.CreateFilesParams) error {
	ctx, done := event.Start(ctx, "server.DidCreateFiles")
	defer done()

	var allChanges []protocol.DocumentChange
	for _, createdFile := range params.Files {
		uri := protocol.DocumentURI(createdFile.URI)
		fh, snapshot, release, err := s.session.FileOf(ctx, uri)
		if err != nil {
			event.Error(ctx, "fail to call fileOf", err)
			continue
		}
		defer release()

		switch snapshot.FileKind(fh) {
		case file.Go:
			change, err := completion.NewFile(ctx, snapshot, fh)
			if err != nil {
				// any error, including "it's not a new file"
				continue
			}
			if change != nil {
				allChanges = append(allChanges, *change)
			}
		default:
		}
	}

	return applyChanges(ctx, s.client, allChanges)
}


================================================
FILE: gopls/internal/server/workspace_symbol.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package server

import (
	"context"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/golang"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/internal/event"
)

func (s *server) Symbol(ctx context.Context, params *protocol.WorkspaceSymbolParams) (_ []protocol.SymbolInformation, rerr error) {
	recordLatency := telemetry.StartLatencyTimer("symbol")
	defer func() {
		recordLatency(ctx, rerr)
	}()

	ctx, done := event.Start(ctx, "server.Symbol")
	defer done()

	views := s.session.Views()
	matcher := s.Options().SymbolMatcher
	style := s.Options().SymbolStyle

	var snapshots []*cache.Snapshot
	for _, v := range views {
		snapshot, release, err := v.Snapshot()
		if err != nil {
			continue // snapshot is shutting down
		}
		// If err is non-nil, the snapshot is shutting down. Skip it.
		defer release()
		snapshots = append(snapshots, snapshot)
	}
	return golang.WorkspaceSymbols(ctx, matcher, style, snapshots, params.Query)
}


================================================
FILE: gopls/internal/settings/analysis.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings

import (
	"log"
	"slices"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/appends"
	"golang.org/x/tools/go/analysis/passes/asmdecl"
	"golang.org/x/tools/go/analysis/passes/assign"
	"golang.org/x/tools/go/analysis/passes/atomic"
	"golang.org/x/tools/go/analysis/passes/atomicalign"
	"golang.org/x/tools/go/analysis/passes/bools"
	"golang.org/x/tools/go/analysis/passes/buildtag"
	"golang.org/x/tools/go/analysis/passes/cgocall"
	"golang.org/x/tools/go/analysis/passes/composite"
	"golang.org/x/tools/go/analysis/passes/copylock"
	"golang.org/x/tools/go/analysis/passes/deepequalerrors"
	"golang.org/x/tools/go/analysis/passes/defers"
	"golang.org/x/tools/go/analysis/passes/directive"
	"golang.org/x/tools/go/analysis/passes/errorsas"
	"golang.org/x/tools/go/analysis/passes/fieldalignment"
	"golang.org/x/tools/go/analysis/passes/framepointer"
	"golang.org/x/tools/go/analysis/passes/hostport"
	"golang.org/x/tools/go/analysis/passes/httpresponse"
	"golang.org/x/tools/go/analysis/passes/ifaceassert"
	"golang.org/x/tools/go/analysis/passes/inline"
	"golang.org/x/tools/go/analysis/passes/loopclosure"
	"golang.org/x/tools/go/analysis/passes/lostcancel"
	"golang.org/x/tools/go/analysis/passes/modernize"
	"golang.org/x/tools/go/analysis/passes/nilfunc"
	"golang.org/x/tools/go/analysis/passes/nilness"
	"golang.org/x/tools/go/analysis/passes/printf"
	"golang.org/x/tools/go/analysis/passes/shadow"
	"golang.org/x/tools/go/analysis/passes/shift"
	"golang.org/x/tools/go/analysis/passes/sigchanyzer"
	"golang.org/x/tools/go/analysis/passes/slog"
	"golang.org/x/tools/go/analysis/passes/sortslice"
	"golang.org/x/tools/go/analysis/passes/stdmethods"
	"golang.org/x/tools/go/analysis/passes/stdversion"
	"golang.org/x/tools/go/analysis/passes/stringintconv"
	"golang.org/x/tools/go/analysis/passes/structtag"
	"golang.org/x/tools/go/analysis/passes/testinggoroutine"
	"golang.org/x/tools/go/analysis/passes/tests"
	"golang.org/x/tools/go/analysis/passes/timeformat"
	"golang.org/x/tools/go/analysis/passes/unmarshal"
	"golang.org/x/tools/go/analysis/passes/unreachable"
	"golang.org/x/tools/go/analysis/passes/unsafeptr"
	"golang.org/x/tools/go/analysis/passes/unusedresult"
	"golang.org/x/tools/go/analysis/passes/unusedwrite"
	"golang.org/x/tools/go/analysis/passes/waitgroup"
	"golang.org/x/tools/gopls/internal/analysis/deprecated"
	"golang.org/x/tools/gopls/internal/analysis/embeddirective"
	"golang.org/x/tools/gopls/internal/analysis/fillreturns"
	"golang.org/x/tools/gopls/internal/analysis/infertypeargs"
	"golang.org/x/tools/gopls/internal/analysis/maprange"
	"golang.org/x/tools/gopls/internal/analysis/nonewvars"
	"golang.org/x/tools/gopls/internal/analysis/noresultvalues"
	"golang.org/x/tools/gopls/internal/analysis/recursiveiter"
	"golang.org/x/tools/gopls/internal/analysis/simplifycompositelit"
	"golang.org/x/tools/gopls/internal/analysis/simplifyrange"
	"golang.org/x/tools/gopls/internal/analysis/simplifyslice"
	"golang.org/x/tools/gopls/internal/analysis/unusedfunc"
	"golang.org/x/tools/gopls/internal/analysis/unusedparams"
	"golang.org/x/tools/gopls/internal/analysis/unusedvariable"
	"golang.org/x/tools/gopls/internal/analysis/writestring"
	"golang.org/x/tools/gopls/internal/analysis/yield"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/goplsexport"
	"honnef.co/go/tools/analysis/lint"
)

var AllAnalyzers = slices.Concat(DefaultAnalyzers, StaticcheckAnalyzers)

// Analyzer augments an [analysis.Analyzer] with additional LSP configuration.
//
// Analyzers are immutable, since they are shared across multiple LSP sessions.
type Analyzer struct {
	analyzer    *analysis.Analyzer
	staticcheck *lint.RawDocumentation // only for staticcheck analyzers
	nonDefault  bool                   // (sense is negated so we can mostly omit it)
	actionKinds []protocol.CodeActionKind
	severity    protocol.DiagnosticSeverity
	tags        []protocol.DiagnosticTag
}

// Analyzer returns the [analysis.Analyzer] that this Analyzer wraps.
func (a *Analyzer) Analyzer() *analysis.Analyzer { return a.analyzer }

// Enabled reports whether the analyzer is enabled by the options.
// This value can be configured per-analysis in user settings.
func (a *Analyzer) Enabled(o *Options) bool {
	// An explicit setting by name takes precedence.
	if v, found := o.Analyses[a.Analyzer().Name]; found {
		return v
	}
	if a.staticcheck != nil {
		// An explicit staticcheck={true,false} setting
		// enables/disables all staticcheck analyzers.
		if o.StaticcheckProvided {
			return o.Staticcheck
		}
		// Respect staticcheck's off-by-default options too.
		// (This applies to only a handful of analyzers.)
		if a.staticcheck.NonDefault {
			return false
		}
	}
	// Respect gopls' default setting.
	return !a.nonDefault
}

// ActionKinds is the set of kinds of code action this analyzer produces.
//
// If left unset, it defaults to QuickFix.
// TODO(rfindley): revisit.
func (a *Analyzer) ActionKinds() []protocol.CodeActionKind { return a.actionKinds }

// Severity is the severity set for diagnostics reported by this analyzer.
// The default severity is SeverityWarning.
//
// While the LSP spec does not specify how severity should be used, here are
// some guiding heuristics:
//   - Error: for parse and type errors, which would stop the build.
//   - Warning: for analyzer diagnostics reporting likely bugs.
//   - Info: for analyzer diagnostics that do not indicate bugs, but may
//     suggest inaccurate or superfluous code.
//   - Hint: for analyzer diagnostics that do not indicate mistakes, but offer
//     simplifications or modernizations. By their nature, hints should
//     generally carry quick fixes.
//
// The difference between Info and Hint is particularly subtle. Importantly,
// Hint diagnostics do not appear in the Problems tab in VS Code, so they are
// less intrusive than Info diagnostics. The rule of thumb is this: use Info if
// the diagnostic is not a bug, but the author probably didn't mean to write
// the code that way. Use Hint if the diagnostic is not a bug and the author
// intended to write the code that way, but there is a simpler or more modern
// way to express the same logic. An 'unused' diagnostic is Info level, since
// the author probably didn't mean to check in unreachable code. A 'modernize'
// or 'deprecated' diagnostic is Hint level, since the author intended to write
// the code that way, but now there is a better way.
func (a *Analyzer) Severity() protocol.DiagnosticSeverity {
	if a.severity == 0 {
		return protocol.SeverityWarning
	}
	return a.severity
}

// Tags is extra tags (unnecessary, deprecated, etc) for diagnostics
// reported by this analyzer.
func (a *Analyzer) Tags() []protocol.DiagnosticTag { return a.tags }

// String returns the name of this analyzer.
func (a *Analyzer) String() string { return a.analyzer.String() }

// DefaultAnalyzers holds the list of Analyzers available to all gopls
// sessions, independent of build version. It is the source from which
// gopls/doc/analyzers.md is generated.
var DefaultAnalyzers = []*Analyzer{
	// See [Analyzer.Severity] for guidance on setting analyzer severity below.

	// The traditional vet suite:
	{analyzer: appends.Analyzer},
	{analyzer: asmdecl.Analyzer},
	{analyzer: assign.Analyzer},
	{analyzer: atomic.Analyzer},
	{analyzer: bools.Analyzer},
	{analyzer: buildtag.Analyzer},
	{analyzer: cgocall.Analyzer},
	{analyzer: composite.Analyzer},
	{analyzer: copylock.Analyzer},
	{analyzer: defers.Analyzer},
	{
		analyzer: deprecated.Analyzer,
		severity: protocol.SeverityHint,
		tags:     []protocol.DiagnosticTag{protocol.Deprecated},
	},
	{analyzer: directive.Analyzer},
	{analyzer: errorsas.Analyzer},
	{analyzer: framepointer.Analyzer},
	{analyzer: httpresponse.Analyzer},
	{analyzer: ifaceassert.Analyzer},
	{analyzer: loopclosure.Analyzer},
	{analyzer: lostcancel.Analyzer},
	{analyzer: nilfunc.Analyzer},
	{analyzer: printf.Analyzer},
	{analyzer: shift.Analyzer},
	{analyzer: sigchanyzer.Analyzer},
	{analyzer: slog.Analyzer},
	{analyzer: stdmethods.Analyzer},
	{analyzer: stdversion.Analyzer},
	{analyzer: stringintconv.Analyzer},
	{analyzer: structtag.Analyzer},
	{analyzer: testinggoroutine.Analyzer},
	{analyzer: tests.Analyzer},
	{analyzer: timeformat.Analyzer},
	{analyzer: unmarshal.Analyzer},
	{analyzer: unreachable.Analyzer},
	{analyzer: unsafeptr.Analyzer},
	{analyzer: unusedresult.Analyzer},

	// not suitable for vet:
	// - some (nilness, yield) use go/ssa; see #59714.
	// - others don't meet the "frequency" criterion;
	//   see GOROOT/src/cmd/vet/README.
	{analyzer: atomicalign.Analyzer},
	{analyzer: deepequalerrors.Analyzer},
	{analyzer: nilness.Analyzer}, // uses go/ssa
	{analyzer: yield.Analyzer},   // uses go/ssa
	{analyzer: sortslice.Analyzer},
	{analyzer: embeddirective.Analyzer},
	{analyzer: waitgroup.Analyzer},     // to appear in cmd/vet@go1.25
	{analyzer: hostport.Analyzer},      // to appear in cmd/vet@go1.25
	{analyzer: recursiveiter.Analyzer}, // under evaluation
	{analyzer: writestring.Analyzer},

	// disabled due to high false positives
	{analyzer: shadow.Analyzer, severity: protocol.SeverityHint, nonDefault: true},         // very noisy
	{analyzer: fieldalignment.Analyzer, severity: protocol.SeverityHint, nonDefault: true}, // #67762, #76237

	// simplifiers and modernizers
	//
	// These analyzers offer mere style fixes on correct code,
	// thus they will never appear in cmd/vet and
	// their severity level is "information".
	//
	// gofmt -s suite
	{
		analyzer:    simplifycompositelit.Analyzer,
		actionKinds: []protocol.CodeActionKind{protocol.SourceFixAll, protocol.QuickFix},
		severity:    protocol.SeverityInformation,
	},
	{
		analyzer:    simplifyrange.Analyzer,
		actionKinds: []protocol.CodeActionKind{protocol.SourceFixAll, protocol.QuickFix},
		severity:    protocol.SeverityInformation,
	},
	{
		analyzer:    simplifyslice.Analyzer,
		actionKinds: []protocol.CodeActionKind{protocol.SourceFixAll, protocol.QuickFix},
		severity:    protocol.SeverityInformation,
	},
	// other simplifiers
	{analyzer: inline.Analyzer, severity: protocol.SeverityHint}, // (in -lazy_edit mode)
	{analyzer: infertypeargs.Analyzer, severity: protocol.SeverityInformation},
	{analyzer: maprange.Analyzer, severity: protocol.SeverityHint},
	{analyzer: unusedparams.Analyzer, severity: protocol.SeverityInformation},
	{analyzer: unusedfunc.Analyzer, severity: protocol.SeverityInformation},
	{analyzer: unusedwrite.Analyzer, severity: protocol.SeverityInformation}, // uses go/ssa
	// the modernize suite
	{analyzer: modernize.AnyAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.AppendClippedAnalyzer, severity: protocol.SeverityHint, nonDefault: true}, // not nil-preserving
	{analyzer: modernize.BLoopAnalyzer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.ErrorsAsTypeModernizer, severity: protocol.SeverityHint},
	{analyzer: modernize.FmtAppendfAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.ForVarAnalyzer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.PlusBuildModernizer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.StdIteratorsModernizer, severity: protocol.SeverityHint},
	{analyzer: modernize.MapsLoopAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.MinMaxAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.NewExprAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.OmitZeroAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.RangeIntAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.ReflectTypeForAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.SlicesContainsAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.SlicesDeleteAnalyzer, severity: protocol.SeverityHint, nonDefault: true}, // not nil-preserving
	{analyzer: modernize.SlicesSortAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.StringsBuilderAnalyzer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.StringsCutModernizer, severity: protocol.SeverityHint},
	{analyzer: modernize.StringsCutPrefixAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.StringsSeqAnalyzer, severity: protocol.SeverityHint},
	{analyzer: modernize.TestingContextAnalyzer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.UnsafeFuncsModernizer, severity: protocol.SeverityHint},
	{analyzer: modernize.WaitGroupGoAnalyzer, severity: protocol.SeverityHint},
	{analyzer: goplsexport.AtomicTypesModernizer, severity: protocol.SeverityHint},

	// type-error analyzers
	// These analyzers enrich go/types errors with suggested fixes.
	// Since they exist only to attach their fixes to type errors, their
	// severity is irrelevant.
	{analyzer: fillreturns.Analyzer},
	{analyzer: nonewvars.Analyzer},
	{analyzer: noresultvalues.Analyzer},
	{analyzer: unusedvariable.Analyzer},
}

func init() {
	if err := inline.Analyzer.Flags.Set("lazy_edits", "true"); err != nil {
		log.Fatalf("setting inline -lazy_edits flag: %v", err)
	}
}


================================================
FILE: gopls/internal/settings/codeactionkind.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings

import "golang.org/x/tools/gopls/internal/protocol"

// This file defines constants for non-standard CodeActions.

// CodeAction kinds specific to gopls
//
// See ../protocol/tsprotocol.go for LSP standard kinds, including
//
//	quickfix
//	refactor
//	refactor.extract
//	refactor.inline
//	refactor.move
//	refactor.rewrite
//	source
//	source.organizeImports
//	source.fixAll
//	notebook
//
// Kinds are hierarchical: "refactor" subsumes "refactor.inline",
// which subsumes "refactor.inline.call". This rule implies that the
// empty string, confusingly named protocol.Empty, subsumes all kinds.
// The "Only" field in a CodeAction request may specify a category
// such as "refactor"; any matching code action will be returned.
//
// All CodeActions returned by gopls use a specific leaf kind such as
// "refactor.inline.call", except for quick fixes, which all use
// "quickfix". TODO(adonovan): perhaps quick fixes should also be
// hierarchical (e.g. quickfix.govulncheck.{reset,upgrade})?
//
// # VS Code
//
// The effects of CodeActionKind on the behavior of VS Code are
// baffling and undocumented. Here's what we have observed.
//
// Clicking on the "Refactor..." menu item shows a submenu of actions
// with kind="refactor.*", and clicking on "Source action..." shows
// actions with kind="source.*". A lightbulb appears in both cases.
//
// A third menu, "Quick fix...", not found on the usual context
// menu but accessible through the command palette or "⌘.",
// does not set the Only field in its request, so the set of
// kinds is determined by how the server interprets the default.
// The LSP 3.18 guidance is that this should be treated
// equivalent to Only=["quickfix"], and that is what gopls
// now does. (If the server responds with more kinds, they will
// be displayed in menu subsections.)
//
// All of these CodeAction requests have triggerkind=Invoked.
//
// Cursor motion also performs a CodeAction request, but with
// triggerkind=Automatic. Even if this returns a mix of action kinds,
// only the "refactor" and "quickfix" actions seem to matter.
// A lightbulb appears if that subset of actions is non-empty, and the
// menu displays them. (This was noisy--see #65167--so gopls now only
// reports diagnostic-associated code actions if kind is Invoked or
// missing.)
//
// None of these CodeAction requests specifies a "kind" restriction;
// the filtering is done on the response, by the client.
//
// In all these menus, VS Code organizes the actions' menu items
// into groups based on their kind, with hardwired captions such as
// "Refactor...", "Extract", "Inline", "More actions", and "Quick fix".
//
// The special category "source.fixAll" is intended for actions that
// are unambiguously safe to apply so that clients may automatically
// apply all actions matching this category on save. (That said, this
// is not VS Code's default behavior; see editor.codeActionsOnSave.)
const (
	// source
	GoAssembly                 protocol.CodeActionKind = "source.assembly"
	GoDoc                      protocol.CodeActionKind = "source.doc"
	GoFreeSymbols              protocol.CodeActionKind = "source.freesymbols"
	GoSplitPackage             protocol.CodeActionKind = "source.splitPackage"
	GoTest                     protocol.CodeActionKind = "source.test"
	GoToggleCompilerOptDetails protocol.CodeActionKind = "source.toggleCompilerOptDetails"
	AddTest                    protocol.CodeActionKind = "source.addTest"
	OrganizeImports            protocol.CodeActionKind = "source.organizeImports"

	// gopls
	GoplsDocFeatures protocol.CodeActionKind = "gopls.doc.features"

	// refactor.rewrite
	RefactorRewriteChangeQuote        protocol.CodeActionKind = "refactor.rewrite.changeQuote"
	RefactorRewriteFillStruct         protocol.CodeActionKind = "refactor.rewrite.fillStruct"
	RefactorRewriteFillSwitch         protocol.CodeActionKind = "refactor.rewrite.fillSwitch"
	RefactorRewriteInvertIf           protocol.CodeActionKind = "refactor.rewrite.invertIf"
	RefactorRewriteJoinLines          protocol.CodeActionKind = "refactor.rewrite.joinLines"
	RefactorRewriteRemoveUnusedParam  protocol.CodeActionKind = "refactor.rewrite.removeUnusedParam"
	RefactorRewriteMoveParamLeft      protocol.CodeActionKind = "refactor.rewrite.moveParamLeft"
	RefactorRewriteMoveParamRight     protocol.CodeActionKind = "refactor.rewrite.moveParamRight"
	RefactorRewriteSplitLines         protocol.CodeActionKind = "refactor.rewrite.splitLines"
	RefactorRewriteEliminateDotImport protocol.CodeActionKind = "refactor.rewrite.eliminateDotImport"
	RefactorRewriteAddTags            protocol.CodeActionKind = "refactor.rewrite.addTags"
	RefactorRewriteRemoveTags         protocol.CodeActionKind = "refactor.rewrite.removeTags"

	// refactor.inline
	RefactorInlineCall     protocol.CodeActionKind = "refactor.inline.call"
	RefactorInlineVariable protocol.CodeActionKind = "refactor.inline.variable"

	// refactor.extract
	RefactorExtractConstant    protocol.CodeActionKind = "refactor.extract.constant"
	RefactorExtractConstantAll protocol.CodeActionKind = "refactor.extract.constant-all"
	RefactorExtractFunction    protocol.CodeActionKind = "refactor.extract.function"
	RefactorExtractMethod      protocol.CodeActionKind = "refactor.extract.method"
	RefactorExtractVariable    protocol.CodeActionKind = "refactor.extract.variable"
	RefactorExtractVariableAll protocol.CodeActionKind = "refactor.extract.variable-all"
	RefactorExtractToNewFile   protocol.CodeActionKind = "refactor.extract.toNewFile"

	// refactor.move
	RefactorMoveType protocol.CodeActionKind = "refactor.move.moveType"

	// Note: add new kinds to:
	// - the SupportedCodeActions map in default.go
	// - the codeActionProducers table in ../golang/codeaction.go
	// - the docs in ../../doc/features/transformation.md
)


================================================
FILE: gopls/internal/settings/default.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings

import (
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
)

var (
	optionsOnce    sync.Once
	defaultOptions *Options
)

// DefaultOptions is the options that are used for Gopls execution independent
// of any externally provided configuration (LSP initialization, command
// invocation, etc.).
//
// It is the source from which gopls/doc/settings.md is generated.
func DefaultOptions(overrides ...func(*Options)) *Options {
	optionsOnce.Do(func() {
		var commands []string
		for _, c := range command.Commands {
			commands = append(commands, c.String())
		}
		defaultOptions = &Options{
			ClientOptions: ClientOptions{
				InsertTextFormat:                           protocol.PlainTextTextFormat,
				PreferredContentFormat:                     protocol.Markdown,
				ConfigurationSupported:                     true,
				DynamicConfigurationSupported:              true,
				DynamicRegistrationSemanticTokensSupported: true,
				DynamicWatchedFilesSupported:               true,
				LineFoldingOnly:                            false,
				HierarchicalDocumentSymbolSupport:          true,
				ImportsSource:                              ImportsSourceGopls,
			},
			ServerOptions: ServerOptions{
				SupportedCodeActions: map[file.Kind]map[protocol.CodeActionKind]bool{
					file.Go: {
						// This should include specific leaves in the tree,
						// (e.g. refactor.inline.call) not generic branches
						// (e.g. refactor.inline or refactor).
						protocol.SourceFixAll:            true,
						protocol.SourceOrganizeImports:   true,
						protocol.QuickFix:                true,
						GoAssembly:                       true,
						GoDoc:                            true,
						GoFreeSymbols:                    true,
						GoSplitPackage:                   true,
						GoplsDocFeatures:                 true,
						RefactorRewriteChangeQuote:       true,
						RefactorRewriteFillStruct:        true,
						RefactorRewriteFillSwitch:        true,
						RefactorRewriteInvertIf:          true,
						RefactorRewriteJoinLines:         true,
						RefactorRewriteRemoveUnusedParam: true,
						RefactorRewriteSplitLines:        true,
						RefactorInlineCall:               true,
						RefactorInlineVariable:           true,
						RefactorExtractConstant:          true,
						RefactorExtractConstantAll:       true,
						RefactorExtractFunction:          true,
						RefactorExtractMethod:            true,
						RefactorExtractVariable:          true,
						RefactorExtractVariableAll:       true,
						RefactorExtractToNewFile:         true,
						RefactorMoveType:                 true, // off while implementation unfinished
						// Not GoTest: it must be explicit in CodeActionParams.Context.Only
					},
					file.Mod: {
						protocol.SourceOrganizeImports: true,
						protocol.QuickFix:              true,
					},
					file.Work: {},
					file.Sum:  {},
					file.Tmpl: {},
				},
				SupportedCommands: commands,
			},
			UserOptions: UserOptions{
				BuildOptions: BuildOptions{
					ExpandWorkspaceToModule: true,
					DirectoryFilters:        []string{"-**/node_modules"},
					TemplateExtensions:      []string{},
					StandaloneTags:          []string{"ignore"},
					WorkspaceFiles:          []string{},
				},
				UIOptions: UIOptions{
					DiagnosticOptions: DiagnosticOptions{
						Annotations: map[Annotation]bool{
							Bounds: true,
							Escape: true,
							Inline: true,
							Nil:    true,
						},
						Vulncheck:                 ModeVulncheckPrompt,
						DiagnosticsDelay:          1 * time.Second,
						DiagnosticsTrigger:        DiagnosticsOnEdit,
						AnalysisProgressReporting: true,
					},
					InlayHintOptions: InlayHintOptions{
						Hints: map[InlayHint]bool{},
					},
					DocumentationOptions: DocumentationOptions{
						HoverKind:    FullDocumentation,
						LinkTarget:   "pkg.go.dev",
						LinksInHover: LinksInHover_LinkTarget,
					},
					NavigationOptions: NavigationOptions{
						ImportShortcut: BothShortcuts,
						SymbolMatcher:  SymbolFastFuzzy,
						SymbolStyle:    DynamicSymbols,
						SymbolScope:    AllSymbolScope,
					},
					CompletionOptions: CompletionOptions{
						Matcher:                        Fuzzy,
						CompletionBudget:               100 * time.Millisecond,
						ExperimentalPostfixCompletions: true,
						CompleteFunctionCalls:          true,
					},
					Codelenses: map[CodeLensSource]bool{
						CodeLensGenerate:          true,
						CodeLensRegenerateCgo:     true,
						CodeLensTidy:              true,
						CodeLensUpgradeDependency: true,
						CodeLensVendor:            true,
						CodeLensRunGovulncheck:    true,
					},
					NewGoFileHeader:        true,
					RenameMovesSubpackages: false,
				},
			},
			InternalOptions: InternalOptions{
				CompleteUnimported:          true,
				CompletionDocumentation:     true,
				DeepCompletion:              true,
				SubdirWatchPatterns:         SubdirWatchPatternsAuto,
				ReportAnalysisProgressAfter: 5 * time.Second,
				TelemetryPrompt:             false,
				LinkifyShowMessage:          false,
				IncludeReplaceInWorkspace:   false,
				ZeroConfig:                  true,
			},
		}
	})
	options := defaultOptions.Clone()
	for _, override := range overrides {
		if override != nil {
			override(options)
		}
	}

	return options
}


================================================
FILE: gopls/internal/settings/settings.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings

import (
	"fmt"
	"maps"
	"math"
	"path/filepath"
	"reflect"
	"strings"
	"time"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
	"golang.org/x/tools/gopls/internal/telemetry"
	"golang.org/x/tools/gopls/internal/util/frob"
)

// An Annotation is a category of Go compiler optimization diagnostic.
type Annotation string

const (
	// Nil controls nil checks.
	Nil Annotation = "nil"

	// Escape controls diagnostics about escape choices.
	Escape Annotation = "escape"

	// Inline controls diagnostics about inlining choices.
	Inline Annotation = "inline"

	// Bounds controls bounds checking diagnostics.
	Bounds Annotation = "bounds"
)

// Options holds various configuration that affects Gopls execution, organized
// by the nature or origin of the settings.
//
// Options must be comparable with reflect.DeepEqual, and serializable with
// [frob.Codec].
//
// This type defines both the logic of LSP-supplied option parsing
// (see [SetOptions]), and the public documentation of options in
// ../../doc/settings.md (generated by gopls/doc/generate).
//
// Each exported field of each embedded type such as "ClientOptions"
// contributes a user-visible option setting. The option name is the
// field name rendered in camelCase. Unlike most Go doc comments,
// these fields should be documented using GitHub markdown.
type Options struct {
	ClientOptions
	ServerOptions
	UserOptions
	InternalOptions
}

// Debug returns a list of "name = value" strings for each Options field.
func (o *Options) Debug() []string {
	var res []string

	var visitStruct func(v reflect.Value, path []string)
	visitStruct = func(v reflect.Value, path []string) {
		for i := range v.NumField() {
			f := v.Field(i)
			ftyp := v.Type().Field(i)
			path := append(path, ftyp.Name)
			if ftyp.Type.Kind() == reflect.Struct {
				visitStruct(f, path)
			} else {
				res = append(res, fmt.Sprintf("%s = %#v",
					strings.Join(path, "."),
					f.Interface()))
			}
		}
	}
	visitStruct(reflect.ValueOf(o).Elem(), nil)

	return res
}

// ClientOptions holds LSP-specific configuration that is provided by the
// client.
//
// ClientOptions must be comparable with reflect.DeepEqual.
type ClientOptions struct {
	ClientInfo                                 protocol.ClientInfo
	InsertTextFormat                           protocol.InsertTextFormat
	InsertReplaceSupported                     bool
	ConfigurationSupported                     bool
	DynamicConfigurationSupported              bool
	DynamicRegistrationSemanticTokensSupported bool
	DynamicWatchedFilesSupported               bool
	RelativePatternsSupported                  bool
	PreferredContentFormat                     protocol.MarkupKind
	LineFoldingOnly                            bool
	HierarchicalDocumentSymbolSupport          bool
	ImportsSource                              ImportsSourceEnum `status:"experimental"`
	SemanticTypes                              []string
	SemanticMods                               []string
	RelatedInformationSupported                bool
	CompletionTags                             bool
	CompletionDeprecated                       bool
	SupportedResourceOperations                []protocol.ResourceOperationKind
	CodeActionResolveOptions                   []string
	ShowDocumentSupported                      bool
	// SupportedWorkDoneProgressFormats specifies the formats supported by the
	// client for handling workdone progress metadata.
	SupportedWorkDoneProgressFormats map[WorkDoneProgressStyle]bool
	// SupportedInteractiveInputTypes specifies the interactive types supported
	// by the client.
	SupportedInteractiveInputTypes map[InteractiveInputType]bool
}

// ServerOptions holds LSP-specific configuration that is provided by the
// server.
//
// ServerOptions must be comparable with reflect.DeepEqual.
type ServerOptions struct {
	SupportedCodeActions map[file.Kind]map[protocol.CodeActionKind]bool
	SupportedCommands    []string
}

// Note: BuildOptions must be comparable with reflect.DeepEqual.
type BuildOptions struct {
	// BuildFlags is the set of flags passed on to the build system when invoked.
	// It is applied to queries like `go list`, which is used when discovering files.
	// The most common use is to set `-tags`.
	BuildFlags []string

	// Env adds environment variables to external commands run by `gopls`, most notably `go list`.
	Env map[string]string

	// DirectoryFilters can be used to exclude unwanted directories from the
	// workspace. By default, all directories are included. Filters are an
	// operator, `+` to include and `-` to exclude, followed by a path prefix
	// relative to the workspace folder. They are evaluated in order, and
	// the last filter that applies to a path controls whether it is included.
	// The path prefix can be empty, so an initial `-` excludes everything.
	//
	// DirectoryFilters also supports the `**` operator to match 0 or more directories.
	//
	// Examples:
	//
	// Exclude node_modules at current depth: `-node_modules`
	//
	// Exclude node_modules at any depth: `-**/node_modules`
	//
	// Include only project_a: `-` (exclude everything), `+project_a`
	//
	// Include only project_a, but not node_modules inside it: `-`, `+project_a`, `-project_a/node_modules`
	DirectoryFilters []string

	// TemplateExtensions gives the extensions of file names that are treated
	// as template files. (The extension
	// is the part of the file name after the final dot.)
	TemplateExtensions []string

	// obsolete, no effect
	MemoryMode string `status:"experimental"`

	// ExpandWorkspaceToModule determines which packages are considered
	// "workspace packages" when the workspace is using modules.
	//
	// Workspace packages affect the scope of workspace-wide operations. Notably,
	// gopls diagnoses all packages considered to be part of the workspace after
	// every keystroke, so by setting "ExpandWorkspaceToModule" to false, and
	// opening a nested workspace directory, you can reduce the amount of work
	// gopls has to do to keep your workspace up to date.
	ExpandWorkspaceToModule bool `status:"experimental"`

	// StandaloneTags specifies a set of build constraints that identify
	// individual Go source files that make up the entire main package of an
	// executable.
	//
	// A common example of standalone main files is the convention of using the
	// directive `//go:build ignore` to denote files that are not intended to be
	// included in any package, for example because they are invoked directly by
	// the developer using `go run`.
	//
	// Gopls considers a file to be a standalone main file if and only if it has
	// package name "main" and has a build directive of the exact form
	// "//go:build tag" or "// +build tag", where tag is among the list of tags
	// configured by this setting. Notably, if the build constraint is more
	// complicated than a simple tag (such as the composite constraint
	// `//go:build tag && go1.18`), the file is not considered to be a standalone
	// main file.
	//
	// This setting is only supported when gopls is built with Go 1.16 or later.
	StandaloneTags []string

	// WorkspaceFiles configures the set of globs that match files defining the
	// logical build of the current workspace. Any on-disk changes to any files
	// matching a glob specified here will trigger a reload of the workspace.
	//
	// This setting need only be customized in environments with a custom
	// GOPACKAGESDRIVER.
	WorkspaceFiles []string
}

// Note: UIOptions must be comparable with reflect.DeepEqual.
type UIOptions struct {
	DocumentationOptions
	CompletionOptions
	NavigationOptions
	DiagnosticOptions
	InlayHintOptions

	// Codelenses overrides the enabled/disabled state of each of gopls'
	// sources of [Code Lenses](codelenses.md).
	//
	// Example Usage:
	//
	// ```json5
	// "gopls": {
	// ...
	//   "codelenses": {
	//     "generate": false,  // Don't show the `go generate` lens.
	//   }
	// ...
	// }
	// ```
	Codelenses map[CodeLensSource]bool

	// SemanticTokens determines whether gopls will return a
	// SemanticTokensProvider at initialization, or respond
	// to request for semantic tokens.
	SemanticTokens bool `status:"experimental"`

	// NoSemanticString turns off the sending of the semantic token 'string'
	//
	// Deprecated: Use SemanticTokenTypes["string"] = false instead. See
	// golang/vscode-go#3632
	NoSemanticString bool `status:"experimental"`

	// NoSemanticNumber turns off the sending of the semantic token 'number'
	//
	// Deprecated: Use SemanticTokenTypes["number"] = false instead. See
	// golang/vscode-go#3632.
	NoSemanticNumber bool `status:"experimental"`

	// SemanticTokenTypes configures the semantic token types. It allows
	// disabling types by setting each value to false.
	// By default, all types are enabled.
	SemanticTokenTypes map[string]bool `status:"experimental"`

	// SemanticTokenModifiers configures the semantic token modifiers. It allows
	// disabling modifiers by setting each value to false.
	// By default, all modifiers are enabled.
	SemanticTokenModifiers map[string]bool `status:"experimental"`

	// NewGoFileHeader enables automatic insertion of the copyright comment
	// and package declaration in a newly created Go file.
	NewGoFileHeader bool

	// RenameMovesSubpackages enables Rename operations on packages to
	// move subdirectories of the target package.
	RenameMovesSubpackages bool `status:"experimental"`
}

// A CodeLensSource identifies an (algorithmic) source of code lenses.
type CodeLensSource string

// CodeLens sources
//
// These identifiers appear in the "codelenses" configuration setting,
// and in the user documentation thereof, which is generated by
// gopls/doc/generate/generate.go parsing this file.
//
// Doc comments should use GitHub Markdown.
// The first line becomes the title.
//
// (For historical reasons, each code lens source identifier typically
// matches the name of one of the command.Commands returned by it,
// but that isn't essential.)
const (
	// Run `go generate`
	//
	// This codelens source annotates any `//go:generate` comments
	// with commands to run `go generate` in this directory, on
	// all directories recursively beneath this one.
	//
	// See [Generating code](https://go.dev/blog/generate) for
	// more details.
	CodeLensGenerate CodeLensSource = "generate"

	// Re-generate cgo declarations
	//
	// This codelens source annotates an `import "C"` declaration
	// with a command to re-run the [cgo
	// command](https://pkg.go.dev/cmd/cgo) to regenerate the
	// corresponding Go declarations.
	//
	// Use this after editing the C code in comments attached to
	// the import, or in C header files included by it.
	CodeLensRegenerateCgo CodeLensSource = "regenerate_cgo"

	// Run govulncheck
	//
	// This codelens source annotates the `module` directive in a go.mod file
	// with a command to run govulncheck synchronously.
	//
	// [Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that
	// computes the set of functions reachable within your application, including
	// dependencies; queries a database of known security vulnerabilities; and
	// reports any potential problems it finds.
	//
	//gopls:status experimental
	CodeLensVulncheck CodeLensSource = "vulncheck"

	// Run govulncheck (legacy)
	//
	// This codelens source annotates the `module` directive in a go.mod file
	// with a command to run Govulncheck asynchronously.
	//
	// [Govulncheck](https://go.dev/blog/vuln) is a static analysis tool that
	// computes the set of functions reachable within your application, including
	// dependencies; queries a database of known security vulnerabilities; and
	// reports any potential problems it finds.
	CodeLensRunGovulncheck CodeLensSource = "run_govulncheck"

	// Run tests and benchmarks
	//
	// This codelens source annotates each `Test` and `Benchmark`
	// function in a `*_test.go` file with a command to run it.
	//
	// This source is off by default because VS Code has
	// a client-side custom UI for testing, and because progress
	// notifications are not a great UX for streamed test output.
	// See:
	// - golang/go#67400 for a discussion of this feature.
	// - https://github.com/joaotavora/eglot/discussions/1402
	//   for an alternative approach.
	CodeLensTest CodeLensSource = "test"

	// Tidy go.mod file
	//
	// This codelens source annotates the `module` directive in a
	// go.mod file with a command to run [`go mod
	// tidy`](https://go.dev/ref/mod#go-mod-tidy), which ensures
	// that the go.mod file matches the source code in the module.
	CodeLensTidy CodeLensSource = "tidy"

	// Update dependencies
	//
	// This codelens source annotates the `module` directive in a
	// go.mod file with commands to:
	//
	// - check for available upgrades,
	// - upgrade direct dependencies, and
	// - upgrade all dependencies transitively.
	CodeLensUpgradeDependency CodeLensSource = "upgrade_dependency"

	// Update vendor directory
	//
	// This codelens source annotates the `module` directive in a
	// go.mod file with a command to run [`go mod
	// vendor`](https://go.dev/ref/mod#go-mod-vendor), which
	// creates or updates the directory named `vendor` in the
	// module root so that it contains an up-to-date copy of all
	// necessary package dependencies.
	CodeLensVendor CodeLensSource = "vendor"
)

// Note: CompletionOptions must be comparable with reflect.DeepEqual.
type CompletionOptions struct {
	// Placeholders enables placeholders for function parameters or struct
	// fields in completion responses.
	UsePlaceholders bool

	// CompletionBudget is the soft latency goal for completion requests. Most
	// requests finish in a couple milliseconds, but in some cases deep
	// completions can take much longer. As we use up our budget we
	// dynamically reduce the search scope to ensure we return timely
	// results. Zero means unlimited.
	CompletionBudget time.Duration `status:"debug"`

	// Matcher sets the algorithm that is used when calculating completion
	// candidates.
	Matcher Matcher `status:"advanced"`

	// ExperimentalPostfixCompletions enables artificial method snippets
	// such as "someSlice.sort!".
	ExperimentalPostfixCompletions bool `status:"experimental"`

	// CompleteFunctionCalls enables function call completion.
	//
	// When completing a statement, or when a function return type matches the
	// expected of the expression being completed, completion may suggest call
	// expressions (i.e. may include parentheses).
	CompleteFunctionCalls bool
}

// Note: DocumentationOptions must be comparable with reflect.DeepEqual.
type DocumentationOptions struct {
	// HoverKind controls the information that appears in the hover text.
	// SingleLine is intended for use only by authors of editor plugins.
	HoverKind HoverKind

	// LinkTarget is the base URL for links to Go package
	// documentation returned by LSP operations such as Hover and
	// DocumentLinks and in the CodeDescription field of each
	// Diagnostic.
	//
	// It might be one of:
	//
	// * `"godoc.org"`
	// * `"pkg.go.dev"`
	//
	// If company chooses to use its own `godoc.org`, its address can be used as well.
	//
	// Modules matching the GOPRIVATE environment variable will not have
	// documentation links in hover.
	LinkTarget string

	// LinksInHover controls the presence of documentation links in hover markdown.
	LinksInHover LinksInHoverEnum
}

// LinksInHoverEnum has legal values:
//
// - `false`, for no links;
// - `true`, for links to the `linkTarget` domain; or
// - `"gopls"`, for links to gopls' internal documentation viewer.
//
// Note: this type has special logic in loadEnums in generate.go.
// Be sure to reflect enum and doc changes there!
type LinksInHoverEnum int

const (
	LinksInHover_None LinksInHoverEnum = iota
	LinksInHover_LinkTarget
	LinksInHover_Gopls
)

// MarshalJSON implements the json.Marshaler interface, so that the default
// values are formatted correctly in documentation. (See [Options.setOne] for
// the flexible custom unmarshaling behavior).
func (l LinksInHoverEnum) MarshalJSON() ([]byte, error) {
	switch l {
	case LinksInHover_None:
		return []byte("false"), nil
	case LinksInHover_LinkTarget:
		return []byte("true"), nil
	case LinksInHover_Gopls:
		return []byte(`"gopls"`), nil
	default:
		return nil, fmt.Errorf("invalid LinksInHover value %d", l)
	}
}

// Note: FormattingOptions must be comparable with reflect.DeepEqual.
type FormattingOptions struct {
	// Local is the equivalent of the `goimports -local` flag, which puts
	// imports beginning with this string after third-party packages. It should
	// be the prefix of the import path whose imports should be grouped
	// separately.
	//
	// It is used when tidying imports (during an LSP Organize
	// Imports request) or when inserting new ones (for example,
	// during completion); an LSP Formatting request merely sorts the
	// existing imports.
	Local string

	// Gofumpt indicates if we should run gofumpt formatting.
	Gofumpt bool
}

// Note: DiagnosticOptions must be comparable with reflect.DeepEqual,
// and frob-encodable (no interfaces).
type DiagnosticOptions struct {
	// Analyses specify analyses that the user would like to enable or disable.
	// A map of the names of analysis passes that should be enabled/disabled.
	// A full list of analyzers that gopls uses can be found in
	// [analyzers.md](https://github.com/golang/tools/blob/master/gopls/doc/analyzers.md).
	//
	// Example Usage:
	//
	// ```json5
	// ...
	// "analyses": {
	//   "unreachable": false, // Disable the unreachable analyzer.
	//   "unusedvariable": true  // Enable the unusedvariable analyzer.
	// }
	// ...
	// ```
	Analyses map[string]bool

	// Staticcheck configures the default set of analyses staticcheck.io.
	// These analyses are documented on
	// [Staticcheck's website](https://staticcheck.io/docs/checks/).
	//
	// The "staticcheck" option has three values:
	// - false: disable all staticcheck analyzers
	// - true: enable all staticcheck analyzers
	// - unset: enable a subset of staticcheck analyzers
	//   selected by gopls maintainers for runtime efficiency
	//   and analytic precision.
	//
	// Regardless of this setting, individual analyzers can be
	// selectively enabled or disabled using the `analyses` setting.
	Staticcheck         bool `status:"experimental"`
	StaticcheckProvided bool `status:"experimental"` // = "staticcheck" was explicitly provided

	// Annotations specifies the various kinds of compiler
	// optimization details that should be reported as diagnostics
	// when enabled for a package by the "Toggle compiler
	// optimization details" (`gopls.gc_details`) command.
	//
	// (Some users care only about one kind of annotation in their
	// profiling efforts. More importantly, in large packages, the
	// number of annotations can sometimes overwhelm the user
	// interface and exceed the per-file diagnostic limit.)
	//
	// TODO(adonovan): rename this field to CompilerOptDetail.
	Annotations map[Annotation]bool

	// Vulncheck enables vulnerability scanning.
	Vulncheck VulncheckMode `status:"experimental"`

	// DiagnosticsDelay controls the amount of time that gopls waits
	// after the most recent file modification before computing deep diagnostics.
	// Simple diagnostics (parsing and type-checking) are always run immediately
	// on recently modified packages.
	//
	// This option must be set to a valid duration string, for example `"250ms"`.
	DiagnosticsDelay time.Duration `status:"advanced"`

	// DiagnosticsTrigger controls when to run diagnostics.
	DiagnosticsTrigger DiagnosticsTrigger `status:"experimental"`

	// AnalysisProgressReporting controls whether gopls sends progress
	// notifications when construction of its index of analysis facts is taking a
	// long time. Cancelling these notifications will cancel the indexing task,
	// though it will restart after the next change in the workspace.
	//
	// When a package is opened for the first time and heavyweight analyses such as
	// staticcheck are enabled, it can take a while to construct the index of
	// analysis facts for all its dependencies. The index is cached in the
	// filesystem, so subsequent analysis should be faster.
	AnalysisProgressReporting bool
}

type InlayHintOptions struct {
	// Hints specify inlay hints that users want to see. A full list of hints
	// that gopls uses can be found in
	// [inlayHints.md](https://github.com/golang/tools/blob/master/gopls/doc/inlayHints.md).
	Hints map[InlayHint]bool `status:"experimental"`
}

// An InlayHint identifies a category of hint that may be
// independently requested through the "hints" setting.
type InlayHint string

// This is the source from which gopls/doc/inlayHints.md is generated.
const (
	// ParameterNames controls inlay hints for parameter names:
	// ```go
	// 	parseInt(/* str: */ "123", /* radix: */ 8)
	// ```
	ParameterNames InlayHint = "parameterNames"

	// AssignVariableTypes controls inlay hints for variable types in assign statements:
	// ```go
	// 	i/* int*/, j/* int*/ := 0, len(r)-1
	// ```
	AssignVariableTypes InlayHint = "assignVariableTypes"

	// ConstantValues controls inlay hints for constant values:
	// ```go
	// 	const (
	// 		KindNone   Kind = iota/* = 0*/
	// 		KindPrint/*  = 1*/
	// 		KindPrintf/* = 2*/
	// 		KindErrorf/* = 3*/
	// 	)
	// ```
	ConstantValues InlayHint = "constantValues"

	// RangeVariableTypes controls inlay hints for variable types in range statements:
	// ```go
	// 	for k/* int*/, v/* string*/ := range []string{} {
	// 		fmt.Println(k, v)
	// 	}
	// ```
	RangeVariableTypes InlayHint = "rangeVariableTypes"

	// CompositeLiteralTypes controls inlay hints for composite literal types:
	// ```go
	// 	for _, c := range []struct {
	// 		in, want string
	// 	}{
	// 		/*struct{ in string; want string }*/{"Hello, world", "dlrow ,olleH"},
	// 	}
	// ```
	CompositeLiteralTypes InlayHint = "compositeLiteralTypes"

	// CompositeLiteralFieldNames inlay hints for composite literal field names:
	// ```go
	// 	{/*in: */"Hello, world", /*want: */"dlrow ,olleH"}
	// ```
	CompositeLiteralFieldNames InlayHint = "compositeLiteralFields"

	// FunctionTypeParameters inlay hints for implicit type parameters on generic functions:
	// ```go
	// 	myFoo/*[int, string]*/(1, "hello")
	// ```
	FunctionTypeParameters InlayHint = "functionTypeParameters"

	// IgnoredError inlay hints for implicitly discarded errors:
	// ```go
	// 	f.Close() // ignore error
	// ```
	// This check inserts an `// ignore error` hint following any
	// statement that is a function call whose error result is
	// implicitly ignored.
	//
	// To suppress the hint, write an actual comment containing
	// "ignore error" following the call statement, or explicitly
	// assign the result to a blank variable. A handful of common
	// functions such as `fmt.Println` are excluded from the
	// check.
	IgnoredError InlayHint = "ignoredError"
)

type NavigationOptions struct {
	// ImportShortcut specifies whether import statements should link to
	// documentation or go to definitions.
	ImportShortcut ImportShortcut

	// SymbolMatcher sets the algorithm that is used when finding workspace symbols.
	SymbolMatcher SymbolMatcher `status:"advanced"`

	// SymbolStyle controls how symbols are qualified in symbol responses.
	//
	// Example Usage:
	//
	// ```json5
	// "gopls": {
	// ...
	//   "symbolStyle": "Dynamic",
	// ...
	// }
	// ```
	SymbolStyle SymbolStyle `status:"advanced"`

	// SymbolScope controls which packages are searched for workspace/symbol
	// requests. When the scope is "workspace", gopls searches only workspace
	// packages. When the scope is "all", gopls searches all loaded packages,
	// including dependencies and the standard library.
	SymbolScope SymbolScope
}

// UserOptions holds custom Gopls configuration (not part of the LSP) that is
// modified by the client.
//
// UserOptions must be comparable with reflect.DeepEqual.
type UserOptions struct {
	BuildOptions
	UIOptions
	FormattingOptions

	// MaxFileCacheBytes sets a soft limit on the file cache size in bytes.
	// If zero, the default budget is used.
	//
	// The cache may temporarily use more than this amount.
	// Also, this parameter limits file contents; disk block usage
	// as measured by du(1) may be significantly higher.
	MaxFileCacheBytes int64 `status:"experimental"`

	// VerboseOutput enables additional debug logging.
	VerboseOutput bool `status:"debug"`
}

// EnvSlice returns Env as a slice of k=v strings.
func (u *UserOptions) EnvSlice() []string {
	var result []string
	for k, v := range u.Env {
		result = append(result, fmt.Sprintf("%v=%v", k, v))
	}
	return result
}

// SetEnvSlice sets Env from a slice of k=v strings.
func (u *UserOptions) SetEnvSlice(env []string) {
	u.Env = map[string]string{}
	for _, kv := range env {
		split := strings.SplitN(kv, "=", 2)
		if len(split) != 2 {
			continue
		}
		u.Env[split[0]] = split[1]
	}
}

type WorkDoneProgressStyle string

const WorkDoneProgressStyleLog WorkDoneProgressStyle = "log"

type InteractiveInputType string

const (
	InteractiveInputTypeString  InteractiveInputType = "string"
	InteractiveInputTypeFileURI InteractiveInputType = "fileURI"
	InteractiveInputTypeBool    InteractiveInputType = "bool"
	InteractiveInputTypeNumber  InteractiveInputType = "number"
	InteractiveInputTypeEnum    InteractiveInputType = "enum"
	InteractiveInputTypeList    InteractiveInputType = "list"
)

// InternalOptions contains settings that are not intended for use by the
// average user. These may be settings used by tests or outdated settings that
// will soon be deprecated. Some of these settings may not even be configurable
// by the user.
//
// TODO(rfindley): even though these settings are not intended for
// modification, some of them should be surfaced in our documentation.
type InternalOptions struct {
	// MCPTools configures enabled tools (by tool name), overriding the defaults.
	MCPTools map[string]bool

	// VerboseWorkDoneProgress controls whether the LSP server should send
	// progress reports for all work done outside the scope of an RPC.
	// Used by the regression tests.
	VerboseWorkDoneProgress bool

	// The following options were previously available to users, but they
	// really shouldn't be configured by anyone other than "power users".

	// CompletionDocumentation enables documentation with completion results.
	CompletionDocumentation bool

	// CompleteUnimported enables completion for packages that you do not
	// currently import.
	CompleteUnimported bool

	// DeepCompletion enables the ability to return completions from deep
	// inside relevant entities, rather than just the locally accessible ones.
	//
	// Consider this example:
	//
	// ```go
	// package main
	//
	// import "fmt"
	//
	// type wrapString struct {
	//     str string
	// }
	//
	// func main() {
	//     x := wrapString{"hello world"}
	//     fmt.Printf(<>)
	// }
	// ```
	//
	// At the location of the `<>` in this program, deep completion would suggest
	// the result `x.str`.
	DeepCompletion bool

	// ShowBugReports causes a message to be shown when the first bug is reported
	// on the server.
	// This option applies only during initialization.
	ShowBugReports bool

	// SubdirWatchPatterns configures the file watching glob patterns registered
	// by gopls.
	//
	// Some clients (namely VS Code) do not send workspace/didChangeWatchedFile
	// notifications for files contained in a directory when that directory is
	// deleted:
	// https://github.com/microsoft/vscode/issues/109754
	//
	// In this case, gopls would miss important notifications about deleted
	// packages. To work around this, gopls registers a watch pattern for each
	// directory containing Go files.
	//
	// Unfortunately, other clients experience performance problems with this
	// many watch patterns, so there is no single behavior that works well for
	// all clients.
	//
	// The "subdirWatchPatterns" setting allows configuring this behavior. Its
	// default value of "auto" attempts to guess the correct behavior based on
	// the client name. We'd love to avoid this specialization, but as described
	// above there is no single value that works for all clients.
	//
	// If any LSP client does not behave well with the default value (for
	// example, if like VS Code it drops file notifications), please file an
	// issue.
	SubdirWatchPatterns SubdirWatchPatterns

	// ReportAnalysisProgressAfter sets the duration for gopls to wait before starting
	// progress reporting for ongoing go/analysis passes.
	//
	// It is intended to be used for testing only.
	ReportAnalysisProgressAfter time.Duration

	// TelemetryPrompt controls whether gopls prompts about enabling Go telemetry.
	//
	// Once the prompt is answered, gopls doesn't ask again, but TelemetryPrompt
	// can prevent the question from ever being asked in the first place.
	TelemetryPrompt bool

	// LinkifyShowMessage controls whether the client wants gopls
	// to linkify links in showMessage. e.g. [go.dev](https://go.dev).
	LinkifyShowMessage bool

	// IncludeReplaceInWorkspace controls whether locally replaced modules in a
	// go.mod file are treated like workspace modules.
	// Or in other words, if a go.mod file with local replaces behaves like a
	// go.work file.
	IncludeReplaceInWorkspace bool

	// ZeroConfig enables the zero-config algorithm for workspace layout,
	// dynamically creating build configurations for different modules,
	// directories, and GOOS/GOARCH combinations to cover open files.
	ZeroConfig bool

	// PullDiagnostics enables support for pull diagnostics.
	//
	// TODO(rfindley): make pull diagnostics robust, and remove this option,
	// allowing pull diagnostics by default.
	PullDiagnostics bool
}

type SubdirWatchPatterns string

const (
	SubdirWatchPatternsOn   SubdirWatchPatterns = "on"
	SubdirWatchPatternsOff  SubdirWatchPatterns = "off"
	SubdirWatchPatternsAuto SubdirWatchPatterns = "auto"
)

type ImportShortcut string

const (
	BothShortcuts      ImportShortcut = "Both"
	LinkShortcut       ImportShortcut = "Link"
	DefinitionShortcut ImportShortcut = "Definition"
)

func (s ImportShortcut) ShowLinks() bool {
	return s == BothShortcuts || s == LinkShortcut
}

func (s ImportShortcut) ShowDefinition() bool {
	return s == BothShortcuts || s == DefinitionShortcut
}

// ImportsSourceEnum has legal values:
//
// - `off` to disable searching the file system for imports
// - `gopls` to use the metadata graph and module cache index
// - `goimports` for the old behavior, to be deprecated
type ImportsSourceEnum string

const (
	ImportsSourceOff       ImportsSourceEnum = "off"
	ImportsSourceGopls     ImportsSourceEnum = "gopls"
	ImportsSourceGoimports ImportsSourceEnum = "goimports"
)

type Matcher string

const (
	Fuzzy           Matcher = "Fuzzy"
	CaseInsensitive Matcher = "CaseInsensitive"
	CaseSensitive   Matcher = "CaseSensitive"
)

// A SymbolMatcher controls the matching of symbols for workspace/symbol
// requests.
type SymbolMatcher string

const (
	SymbolFuzzy           SymbolMatcher = "Fuzzy"
	SymbolFastFuzzy       SymbolMatcher = "FastFuzzy"
	SymbolCaseInsensitive SymbolMatcher = "CaseInsensitive"
	SymbolCaseSensitive   SymbolMatcher = "CaseSensitive"
)

// A SymbolStyle controls the formatting of symbols in workspace/symbol results.
type SymbolStyle string

const (
	// PackageQualifiedSymbols is package qualified symbols i.e.
	// "pkg.Foo.Field".
	PackageQualifiedSymbols SymbolStyle = "Package"
	// FullyQualifiedSymbols is fully qualified symbols, i.e.
	// "path/to/pkg.Foo.Field".
	FullyQualifiedSymbols SymbolStyle = "Full"
	// DynamicSymbols uses whichever qualifier results in the highest scoring
	// match for the given symbol query. Here a "qualifier" is any "/" or "."
	// delimited suffix of the fully qualified symbol. i.e. "to/pkg.Foo.Field" or
	// just "Foo.Field".
	DynamicSymbols SymbolStyle = "Dynamic"
)

// A SymbolScope controls the search scope for workspace/symbol requests.
type SymbolScope string

const (
	// WorkspaceSymbolScope matches symbols in workspace packages only.
	WorkspaceSymbolScope SymbolScope = "workspace"
	// AllSymbolScope matches symbols in any loaded package, including
	// dependencies.
	AllSymbolScope SymbolScope = "all"
)

type HoverKind string

const (
	SingleLine            HoverKind = "SingleLine"
	NoDocumentation       HoverKind = "NoDocumentation"
	SynopsisDocumentation HoverKind = "SynopsisDocumentation"
	FullDocumentation     HoverKind = "FullDocumentation"

	// Structured is a misguided experimental setting that returns a JSON
	// hover format. This setting should not be used, as it will be removed in a
	// future release of gopls.
	Structured HoverKind = "Structured"
)

type VulncheckMode string

const (
	// Vulncheck can be triggered via prompt.
	ModeVulncheckPrompt VulncheckMode = "Prompt"
	// Disable vulnerability analysis.
	ModeVulncheckOff VulncheckMode = "Off"
	// In Imports mode, `gopls` will report vulnerabilities that affect packages
	// directly and indirectly used by the analyzed main module.
	ModeVulncheckImports VulncheckMode = "Imports"

	// TODO: VulncheckRequire, VulncheckCallgraph
)

type DiagnosticsTrigger string

const (
	// Trigger diagnostics on file edit and save. (default)
	DiagnosticsOnEdit DiagnosticsTrigger = "Edit"
	// Trigger diagnostics only on file save. Events like initial workspace load
	// or configuration change will still trigger diagnostics.
	DiagnosticsOnSave DiagnosticsTrigger = "Save"
	// TODO: support "Manual"?
)

type CounterPath = telemetry.CounterPath

// Set updates *Options based on the provided JSON value:
// null, bool, string, number, array, or object.
//
// The applied result describes settings that were applied. Each CounterPath
// contains at least the name of the setting, but may also include sub-setting
// names for settings that are themselves maps, and/or a non-empty bucket name
// when bucketing is desirable.
//
// On failure, it returns one or more non-nil errors.
func (o *Options) Set(value any) (applied []CounterPath, errs []error) {
	switch value := value.(type) {
	case nil:
	case map[string]any:
		seen := make(map[string]struct{})
		for name, value := range value {
			// Use only the last segment of a dotted name such as
			// ui.navigation.symbolMatcher. The other segments
			// are discarded, even without validation (!).
			// (They are supported to enable hierarchical names
			// in the VS Code graphical configuration UI.)
			split := strings.Split(name, ".")
			name = split[len(split)-1]

			if _, ok := seen[name]; ok {
				errs = append(errs, fmt.Errorf("duplicate value for %s", name))
			}
			seen[name] = struct{}{}

			paths, err := o.setOne(name, value)
			if err != nil {
				err := fmt.Errorf("setting option %q: %w", name, err)
				errs = append(errs, err)
			}
			_, soft := err.(*SoftError)
			if err == nil || soft {
				if len(paths) == 0 {
					path := CounterPath{name, ""}
					applied = append(applied, path)
				} else {
					for _, subpath := range paths {
						path := append(CounterPath{name}, subpath...)
						applied = append(applied, path)
					}
				}
			}
		}
	default:
		errs = append(errs, fmt.Errorf("invalid options type %T (want JSON null or object)", value))
	}
	return applied, errs
}

func (o *Options) ForClientCapabilities(clientInfo *protocol.ClientInfo, caps protocol.ClientCapabilities) {
	if clientInfo != nil {
		o.ClientInfo = *clientInfo
	}
	if caps.Workspace.WorkspaceEdit != nil {
		o.SupportedResourceOperations = caps.Workspace.WorkspaceEdit.ResourceOperations
	}
	// Check if the client supports snippets in completion items.
	if c := caps.TextDocument.Completion; c.CompletionItem.SnippetSupport {
		o.InsertTextFormat = protocol.SnippetTextFormat
	}
	o.InsertReplaceSupported = caps.TextDocument.Completion.CompletionItem.InsertReplaceSupport
	if caps.Window.ShowDocument != nil {
		o.ShowDocumentSupported = caps.Window.ShowDocument.Support
	}
	// Check if the client supports configuration messages.
	o.ConfigurationSupported = caps.Workspace.Configuration
	o.DynamicConfigurationSupported = caps.Workspace.DidChangeConfiguration.DynamicRegistration
	o.DynamicRegistrationSemanticTokensSupported = caps.TextDocument.SemanticTokens.DynamicRegistration
	o.DynamicWatchedFilesSupported = caps.Workspace.DidChangeWatchedFiles.DynamicRegistration
	o.RelativePatternsSupported = caps.Workspace.DidChangeWatchedFiles.RelativePatternSupport

	// Check which types of content format are supported by this client.
	if hover := caps.TextDocument.Hover; hover != nil && len(hover.ContentFormat) > 0 {
		o.PreferredContentFormat = hover.ContentFormat[0]
	}
	// Check if the client supports only line folding.

	if fr := caps.TextDocument.FoldingRange; fr != nil {
		// TODO(pjw): add telemetry
		o.LineFoldingOnly = fr.LineFoldingOnly
	}
	// Check if the client supports hierarchical document symbols.
	o.HierarchicalDocumentSymbolSupport = caps.TextDocument.DocumentSymbol.HierarchicalDocumentSymbolSupport

	// Client's semantic tokens
	o.SemanticTypes = caps.TextDocument.SemanticTokens.TokenTypes
	o.SemanticMods = caps.TextDocument.SemanticTokens.TokenModifiers
	// we don't need Requests, as we support full functionality
	// we don't need Formats, as there is only one, for now

	// Check if the client supports diagnostic related information.
	o.RelatedInformationSupported = caps.TextDocument.PublishDiagnostics.RelatedInformation
	// Check if the client completion support includes tags (preferred) or deprecation
	if caps.TextDocument.Completion.CompletionItem.TagSupport != nil &&
		caps.TextDocument.Completion.CompletionItem.TagSupport.ValueSet != nil {
		o.CompletionTags = true
	} else if caps.TextDocument.Completion.CompletionItem.DeprecatedSupport {
		o.CompletionDeprecated = true
	}

	// Check if the client supports code actions resolving.
	if caps.TextDocument.CodeAction.DataSupport && caps.TextDocument.CodeAction.ResolveSupport != nil {
		o.CodeActionResolveOptions = caps.TextDocument.CodeAction.ResolveSupport.Properties
	}

	// Client experimental capabilities.
	if experimental, ok := caps.Experimental.(map[string]any); ok {
		if formats, ok := experimental["progressMessageStyles"].([]any); ok {
			o.SupportedWorkDoneProgressFormats = make(map[WorkDoneProgressStyle]bool, len(formats))
			for _, f := range formats {
				o.SupportedWorkDoneProgressFormats[WorkDoneProgressStyle(f.(string))] = true
			}
		}

		if inputTypes, ok := experimental["interactiveInputTypes"].([]any); ok {
			o.SupportedInteractiveInputTypes = make(map[InteractiveInputType]bool, len(inputTypes))
			for _, t := range inputTypes {
				o.SupportedInteractiveInputTypes[InteractiveInputType(t.(string))] = true
			}
		}
	}
}

var codec = frob.CodecFor[*Options]()

func (o *Options) Clone() *Options {
	data := codec.Encode(o)
	var clone *Options
	codec.Decode(data, &clone)
	return clone
}

// validateDirectoryFilter validates if the filter string
// - is not empty
// - start with either + or -
// - doesn't contain currently unsupported glob operators: *, ?
func validateDirectoryFilter(ifilter string) (string, error) {
	filter := fmt.Sprint(ifilter)
	if filter == "" || (filter[0] != '+' && filter[0] != '-') {
		return "", fmt.Errorf("invalid filter %v, must start with + or -", filter)
	}
	segs := strings.Split(filter[1:], "/")
	unsupportedOps := [...]string{"?", "*"}
	for _, seg := range segs {
		if seg != "**" {
			for _, op := range unsupportedOps {
				if strings.Contains(seg, op) {
					return "", fmt.Errorf("invalid filter %v, operator %v not supported. If you want to have this operator supported, consider filing an issue", filter, op)
				}
			}
		}
	}

	return strings.TrimRight(filepath.FromSlash(filter), "/"), nil
}

// setOne updates a field of o based on the name and value.
//
// The applied result describes the counter values to be updated as a result of
// the applied setting. If the result is nil, the default counter for this
// setting should be updated.
//
// For example, if the setting name is "foo",
//   - If applied is nil, update the count for "foo".
//   - If applied is []CounterPath{{"bucket"}}, update the count for
//     foo:bucket.
//   - If applied is []CounterPath{{"a","b"}, {"c","d"}}, update foo/a:b and
//     foo/c:d.
//
// It returns an error if the value was invalid or duplicate.
// It is the caller's responsibility to augment the error with 'name'.
func (o *Options) setOne(name string, value any) (applied []CounterPath, _ error) {
	switch name {
	case "env":
		env, ok := value.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("invalid type %T (want JSON object)", value)
		}
		if o.Env == nil {
			o.Env = make(map[string]string)
		}
		for k, v := range env {
			// For historic compatibility, we accept int too (e.g. CGO_ENABLED=1).
			switch v.(type) {
			case string, int:
				o.Env[k] = fmt.Sprint(v)
			default:
				return nil, fmt.Errorf("invalid map value %T (want string)", v)
			}
		}
		return nil, nil

	case "buildFlags":
		return nil, setStringSlice(&o.BuildFlags, value)

	case "directoryFilters":
		filterStrings, err := asStringSlice(value)
		if err != nil {
			return nil, err
		}
		var filters []string
		for _, filterStr := range filterStrings {
			filter, err := validateDirectoryFilter(filterStr)
			if err != nil {
				return nil, err
			}
			filters = append(filters, strings.TrimRight(filepath.FromSlash(filter), "/"))
		}
		o.DirectoryFilters = filters
		return nil, nil

	case "workspaceFiles":
		return nil, setStringSlice(&o.WorkspaceFiles, value)
	case "completionDocumentation":
		return setBool(&o.CompletionDocumentation, value)
	case "usePlaceholders":
		return setBool(&o.UsePlaceholders, value)
	case "deepCompletion":
		return setBool(&o.DeepCompletion, value)
	case "completeUnimported":
		return setBool(&o.CompleteUnimported, value)
	case "completionBudget":
		return nil, setDuration(&o.CompletionBudget, value)
	case "importsSource":
		return setEnum(&o.ImportsSource, value,
			ImportsSourceOff,
			ImportsSourceGopls,
			ImportsSourceGoimports)
	case "matcher":
		return setEnum(&o.Matcher, value,
			Fuzzy,
			CaseSensitive,
			CaseInsensitive)

	case "symbolMatcher":
		return setEnum(&o.SymbolMatcher, value,
			SymbolFuzzy,
			SymbolFastFuzzy,
			SymbolCaseInsensitive,
			SymbolCaseSensitive)

	case "symbolStyle":
		return setEnum(&o.SymbolStyle, value,
			FullyQualifiedSymbols,
			PackageQualifiedSymbols,
			DynamicSymbols)

	case "symbolScope":
		return setEnum(&o.SymbolScope, value,
			WorkspaceSymbolScope,
			AllSymbolScope)

	case "hoverKind":
		// TODO(rfindley): reinstate the deprecation of Structured hover by making
		// it a warning in gopls v0.N+1, and removing it in gopls v0.N+2.
		return setEnum(&o.HoverKind, value,
			NoDocumentation,
			SingleLine,
			SynopsisDocumentation,
			FullDocumentation,
			Structured,
		)

	case "linkTarget":
		return nil, setString(&o.LinkTarget, value)

	case "linksInHover":
		switch value {
		case false:
			o.LinksInHover = LinksInHover_None
		case true:
			o.LinksInHover = LinksInHover_LinkTarget
		case "gopls":
			o.LinksInHover = LinksInHover_Gopls
		default:
			return nil, fmt.Errorf(`invalid value %s; expect false, true, or "gopls"`, value)
		}
		return nil, nil

	case "importShortcut":
		return setEnum(&o.ImportShortcut, value,
			BothShortcuts,
			LinkShortcut,
			DefinitionShortcut)

	case "analyses":
		return setBoolMap(&o.Analyses, value)

	case "hints":
		return setBoolMap(&o.Hints, value)

	case "annotations":
		return setAnnotationMap(&o.Annotations, value)

	case "vulncheck":
		return setEnum(&o.Vulncheck, value,
			ModeVulncheckOff,
			ModeVulncheckImports,
			ModeVulncheckPrompt)

	case "codelenses", "codelens":
		lensOverrides, err := asBoolMap[CodeLensSource](value)
		if err != nil {
			return nil, err
		}
		if o.Codelenses == nil {
			o.Codelenses = make(map[CodeLensSource]bool)
		}
		o.Codelenses = maps.Clone(o.Codelenses)
		maps.Copy(o.Codelenses, lensOverrides)

		var counts []CounterPath
		for k, v := range lensOverrides {
			counts = append(counts, CounterPath{string(k), fmt.Sprint(v)})
		}

		var errs []string
		if name == "codelens" {
			errs = append(errs, deprecatedError("codelenses").Error())
		}
		if lensOverrides[CodeLensRunGovulncheck] && lensOverrides[CodeLensVulncheck] {
			errs = append(errs, "The 'run_govulncheck' codelens is superseded by the 'vulncheck' codelens. Only 'vulncheck' should be set.")
		}
		if len(errs) > 0 {
			return counts, &SoftError{msg: strings.Join(errs, "\n")}
		}
		return counts, nil

	case "staticcheck":
		o.StaticcheckProvided = true
		return setBool(&o.Staticcheck, value)

	case "local":
		return nil, setString(&o.Local, value)

	case "maxFileCacheBytes":
		return setInt64(&o.MaxFileCacheBytes, value)

	case "verboseOutput":
		return setBool(&o.VerboseOutput, value)

	case "verboseWorkDoneProgress":
		return setBool(&o.VerboseWorkDoneProgress, value)

	case "showBugReports":
		return setBool(&o.ShowBugReports, value)

	case "gofumpt":
		return setBool(&o.Gofumpt, value)

	case "completeFunctionCalls":
		return setBool(&o.CompleteFunctionCalls, value)

	case "semanticTokens":
		return setBool(&o.SemanticTokens, value)

	// TODO(hxjiang): deprecate noSemanticString and noSemanticNumber.
	case "noSemanticString":
		counts, err := setBool(&o.NoSemanticString, value)
		if err != nil {
			return nil, err
		}
		return counts, &SoftError{"noSemanticString setting is deprecated, use semanticTokenTypes instead (though you can continue to apply them for the time being)."}

	case "noSemanticNumber":
		counts, err := setBool(&o.NoSemanticNumber, value)
		if err != nil {
			return nil, err
		}
		return counts, &SoftError{"noSemanticNumber setting is deprecated, use semanticTokenTypes instead (though you can continue to apply them for the time being)."}

	case "semanticTokenTypes":
		return setBoolMap(&o.SemanticTokenTypes, value)

	case "semanticTokenModifiers":
		return setBoolMap(&o.SemanticTokenModifiers, value)

	case "newGoFileHeader":
		return setBool(&o.NewGoFileHeader, value)

	case "expandWorkspaceToModule":
		// See golang/go#63536: we can consider deprecating
		// expandWorkspaceToModule, but probably need to change the default
		// behavior in that case to *not* expand to the module.
		return setBool(&o.ExpandWorkspaceToModule, value)

	case "experimentalPostfixCompletions":
		return setBool(&o.ExperimentalPostfixCompletions, value)

	case "templateExtensions":
		switch value := value.(type) {
		case []any:
			return nil, setStringSlice(&o.TemplateExtensions, value)
		case nil:
			o.TemplateExtensions = nil
		default:
			return nil, fmt.Errorf("unexpected type %T (want JSON array of string)", value)
		}
		return nil, nil

	case "diagnosticsDelay":
		return nil, setDuration(&o.DiagnosticsDelay, value)

	case "diagnosticsTrigger":
		return setEnum(&o.DiagnosticsTrigger, value,
			DiagnosticsOnEdit,
			DiagnosticsOnSave)

	case "analysisProgressReporting":
		return setBool(&o.AnalysisProgressReporting, value)

	case "standaloneTags":
		return nil, setStringSlice(&o.StandaloneTags, value)

	case "subdirWatchPatterns":
		return setEnum(&o.SubdirWatchPatterns, value,
			SubdirWatchPatternsOn,
			SubdirWatchPatternsOff,
			SubdirWatchPatternsAuto)

	case "reportAnalysisProgressAfter":
		return nil, setDuration(&o.ReportAnalysisProgressAfter, value)

	case "telemetryPrompt":
		return setBool(&o.TelemetryPrompt, value)

	case "linkifyShowMessage":
		return setBool(&o.LinkifyShowMessage, value)

	case "includeReplaceInWorkspace":
		return setBool(&o.IncludeReplaceInWorkspace, value)

	case "zeroConfig":
		return setBool(&o.ZeroConfig, value)

	case "pullDiagnostics":
		return setBool(&o.PullDiagnostics, value)

	case "mcpTools":
		return setBoolMap(&o.MCPTools, value)

	case "renameMovesSubpackages":
		return setBool(&o.RenameMovesSubpackages, value)

	// deprecated and renamed settings
	//
	// These should never be deleted: there is essentially no cost
	// to providing a better error message indefinitely; it's not
	// as if we would ever want to recycle the name of a setting.

	// renamed
	case "experimentalDisabledAnalyses":
		return nil, deprecatedError("analyses")

	case "disableDeepCompletion":
		return nil, deprecatedError("deepCompletion")

	case "disableFuzzyMatching":
		return nil, deprecatedError("fuzzyMatching")

	case "wantCompletionDocumentation":
		return nil, deprecatedError("completionDocumentation")

	case "wantUnimportedCompletions":
		return nil, deprecatedError("completeUnimported")

	case "fuzzyMatching":
		return nil, deprecatedError("matcher")

	case "caseSensitiveCompletion":
		return nil, deprecatedError("matcher")

	case "experimentalDiagnosticsDelay":
		return nil, deprecatedError("diagnosticsDelay")

	// deprecated

	case "allowImplicitNetworkAccess":
		return nil, deprecatedError("")

	case "memoryMode":
		return nil, deprecatedError("")

	case "tempModFile":
		return nil, deprecatedError("")

	case "experimentalWorkspaceModule":
		return nil, deprecatedError("")

	case "experimentalTemplateSupport":
		return nil, deprecatedError("")

	case "experimentalWatchedFileDelay":
		return nil, deprecatedError("")

	case "experimentalPackageCacheKey":
		return nil, deprecatedError("")

	case "allowModfileModifications":
		return nil, deprecatedError("")

	case "allExperiments":
		// golang/go#65548: this setting is a no-op, but we fail don't report it as
		// deprecated, since the nightly VS Code injects it.
		//
		// If, in the future, VS Code stops injecting this, we could theoretically
		// report an error here, but it also seems harmless to keep ignoring this
		// setting forever.
		return nil, nil

	case "experimentalUseInvalidMetadata":
		return nil, deprecatedError("")

	case "newDiff":
		return nil, deprecatedError("")

	case "wantSuggestedFixes":
		return nil, deprecatedError("")

	case "noIncrementalSync":
		return nil, deprecatedError("")

	case "watchFileChanges":
		return nil, deprecatedError("")

	case "go-diff":
		return nil, deprecatedError("")

	default:
		return nil, fmt.Errorf("unexpected setting")
	}
}

// EnabledSemanticTokenModifiers returns a map of modifiers to boolean.
func (o *Options) EnabledSemanticTokenModifiers() map[semtok.Modifier]bool {
	copy := make(map[semtok.Modifier]bool, len(o.SemanticTokenModifiers))
	for k, v := range o.SemanticTokenModifiers {
		copy[semtok.Modifier(k)] = v
	}
	return copy
}

// EnabledSemanticTokenTypes returns a map of types to boolean.
func (o *Options) EnabledSemanticTokenTypes() map[semtok.Type]bool {
	copy := make(map[semtok.Type]bool, len(o.SemanticTokenTypes))
	for k, v := range o.SemanticTokenTypes {
		copy[semtok.Type(k)] = v
	}
	if o.NoSemanticString {
		copy[semtok.TokString] = false
	}
	if o.NoSemanticNumber {
		copy[semtok.TokNumber] = false
	}
	return copy
}

// A SoftError is an error that does not affect the functionality of gopls.
type SoftError struct {
	msg string
}

func (e *SoftError) Error() string {
	return e.msg
}

// deprecatedError reports the current setting as deprecated.
// The optional replacement is suggested to the user.
func deprecatedError(replacement string) error {
	msg := "this setting is deprecated"
	if replacement != "" {
		msg = fmt.Sprintf("%s, use %q instead", msg, replacement)
	}
	return &SoftError{msg}
}

// setT() and asT() helpers: the setT forms write to the 'dest *T'
// variable only on success, to reduce boilerplate in Option.set.

func setBool(dest *bool, value any) ([]CounterPath, error) {
	b, err := asBool(value)
	if err != nil {
		return nil, err
	}
	*dest = b
	return []CounterPath{{fmt.Sprint(b)}}, nil
}

func asBool(value any) (bool, error) {
	b, ok := value.(bool)
	if !ok {
		return false, fmt.Errorf("invalid type %T (want bool)", value)
	}
	return b, nil
}

func setDuration(dest *time.Duration, value any) error {
	str, err := asString(value)
	if err != nil {
		return err
	}
	parsed, err := time.ParseDuration(str)
	if err != nil {
		return err
	}
	*dest = parsed
	return nil
}

func setAnnotationMap(dest *map[Annotation]bool, value any) ([]CounterPath, error) {
	all, err := asBoolMap[string](value)
	if err != nil {
		return nil, err
	}
	var counters []CounterPath
	// Default to everything enabled by default.
	m := make(map[Annotation]bool)
	for k, enabled := range all {
		var a Annotation
		cnts, err := setEnum(&a, k,
			Nil,
			Escape,
			Inline,
			Bounds)
		if err != nil {
			// In case of an error, process any legacy values.
			switch k {
			case "noEscape":
				m[Escape] = false
				return nil, fmt.Errorf(`"noEscape" is deprecated, set "Escape: false" instead`)

			case "noNilcheck":
				m[Nil] = false
				return nil, fmt.Errorf(`"noNilcheck" is deprecated, set "Nil: false" instead`)

			case "noInline":
				m[Inline] = false
				return nil, fmt.Errorf(`"noInline" is deprecated, set "Inline: false" instead`)

			case "noBounds":
				m[Bounds] = false
				return nil, fmt.Errorf(`"noBounds" is deprecated, set "Bounds: false" instead`)

			default:
				return nil, err
			}
		}
		counters = append(counters, cnts...)
		m[a] = enabled
	}
	*dest = m
	return counters, nil
}

func setBoolMap[K ~string](dest *map[K]bool, value any) ([]CounterPath, error) {
	m, err := asBoolMap[K](value)
	if err != nil {
		return nil, err
	}
	*dest = m
	var counts []CounterPath
	for k, v := range m {
		counts = append(counts, CounterPath{string(k), fmt.Sprint(v)})
	}
	return counts, nil
}

func asBoolMap[K ~string](value any) (map[K]bool, error) {
	all, ok := value.(map[string]any)
	if !ok {
		return nil, fmt.Errorf("invalid type %T (want JSON object)", value)
	}
	m := make(map[K]bool)
	for a, enabled := range all {
		b, ok := enabled.(bool)
		if !ok {
			return nil, fmt.Errorf("invalid type %T for object field %q", enabled, a)
		}
		m[K(a)] = b
	}
	return m, nil
}

func setString(dest *string, value any) error {
	str, err := asString(value)
	if err != nil {
		return err
	}
	*dest = str
	return nil
}

func asString(value any) (string, error) {
	str, ok := value.(string)
	if !ok {
		return "", fmt.Errorf("invalid type %T (want string)", value)
	}
	return str, nil
}

func setStringSlice(dest *[]string, value any) error {
	slice, err := asStringSlice(value)
	if err != nil {
		return err
	}
	*dest = slice
	return nil
}

func asStringSlice(value any) ([]string, error) {
	array, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("invalid type %T (want JSON array of string)", value)
	}
	var slice []string
	for _, elem := range array {
		str, ok := elem.(string)
		if !ok {
			return nil, fmt.Errorf("invalid array element type %T (want string)", elem)
		}
		slice = append(slice, str)
	}
	return slice, nil
}

func setEnum[S ~string](dest *S, value any, options ...S) ([]CounterPath, error) {
	enum, err := asEnum(value, options...)
	if err != nil {
		return nil, err
	}
	*dest = enum
	return []CounterPath{{string(enum)}}, nil
}

func asEnum[S ~string](value any, options ...S) (S, error) {
	str, err := asString(value)
	if err != nil {
		return "", err
	}
	for _, opt := range options {
		if strings.EqualFold(str, string(opt)) {
			return opt, nil
		}
	}
	return "", fmt.Errorf("invalid option %q for enum", str)
}

func setInt64(dest *int64, value any) ([]CounterPath, error) {
	i, err := asInt64(value)
	if err != nil {
		return nil, err
	}
	*dest = i
	return []CounterPath{{fmt.Sprint(i)}}, nil
}

func asInt64(value any) (int64, error) {
	switch v := value.(type) {

	case float64:
		// Note that this is what we expect since JSON unmarshalling
		// into any produces float64 for numbers.
		if !isFinite(v) {
			return 0, fmt.Errorf("invalid value %v (want finite number)", v)
		}
		if v != math.Trunc(v) {
			return 0, fmt.Errorf("invalid value %v (want integer)", v)
		}
		if v != float64(int64(v)) {
			return 0, fmt.Errorf("invalid value %v (not representable as int64)", v)
		}
		return int64(v), nil
	case int64:
		return v, nil
	case int:
		return int64(v), nil
	default:
		return 0, fmt.Errorf("invalid type %T (want int64)", value)
	}
}

// isFinite reports whether f represents a finite rational value.
// It is equivalent to !math.IsNan(f) && !math.IsInf(f, 0).
func isFinite(f float64) bool {
	return math.Abs(f) <= math.MaxFloat64
}


================================================
FILE: gopls/internal/settings/settings_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings_test

import (
	"reflect"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/clonetest"
	. "golang.org/x/tools/gopls/internal/settings"
)

func TestDefaultsEquivalence(t *testing.T) {
	opts1 := DefaultOptions()
	opts2 := DefaultOptions()
	if !reflect.DeepEqual(opts1, opts2) {
		t.Fatal("default options are not equivalent using reflect.DeepEqual")
	}
}

func TestOptions_Set(t *testing.T) {
	type testCase struct {
		name      string
		value     any
		wantError bool
		check     func(Options) bool
	}
	tests := []testCase{
		{
			name:  "symbolStyle",
			value: "Dynamic",
			check: func(o Options) bool { return o.SymbolStyle == DynamicSymbols },
		},
		{
			name:      "symbolStyle",
			value:     "",
			wantError: true,
			check:     func(o Options) bool { return o.SymbolStyle == "" },
		},
		{
			name:      "symbolStyle",
			value:     false,
			wantError: true,
			check:     func(o Options) bool { return o.SymbolStyle == "" },
		},
		{
			name:  "symbolMatcher",
			value: "caseInsensitive",
			check: func(o Options) bool { return o.SymbolMatcher == SymbolCaseInsensitive },
		},
		{
			name:  "completionBudget",
			value: "2s",
			check: func(o Options) bool { return o.CompletionBudget == 2*time.Second },
		},
		{
			name:  "codelenses",
			value: map[string]any{"generate": true},
			check: func(o Options) bool { return o.Codelenses["generate"] },
		},
		{
			name:  "allExperiments",
			value: true,
			check: func(o Options) bool {
				return true // just confirm that we handle this setting
			},
		},
		{
			name:  "hoverKind",
			value: "FullDocumentation",
			check: func(o Options) bool {
				return o.HoverKind == FullDocumentation
			},
		},
		{
			name:  "hoverKind",
			value: "NoDocumentation",
			check: func(o Options) bool {
				return o.HoverKind == NoDocumentation
			},
		},
		{
			name:  "hoverKind",
			value: "SingleLine",
			check: func(o Options) bool {
				return o.HoverKind == SingleLine
			},
		},
		{
			name:  "hoverKind",
			value: "Structured",
			// wantError: true, // TODO(rfindley): reinstate this error
			check: func(o Options) bool {
				return o.HoverKind == Structured
			},
		},
		{
			name:  "ui.documentation.hoverKind",
			value: "Structured",
			// wantError: true, // TODO(rfindley): reinstate this error
			check: func(o Options) bool {
				return o.HoverKind == Structured
			},
		},
		{
			name:  "hoverKind",
			value: "FullDocumentation",
			check: func(o Options) bool {
				return o.HoverKind == FullDocumentation
			},
		},
		{
			name:  "ui.documentation.hoverKind",
			value: "FullDocumentation",
			check: func(o Options) bool {
				return o.HoverKind == FullDocumentation
			},
		},
		{
			name:  "matcher",
			value: "Fuzzy",
			check: func(o Options) bool {
				return o.Matcher == Fuzzy
			},
		},
		{
			name:  "matcher",
			value: "CaseSensitive",
			check: func(o Options) bool {
				return o.Matcher == CaseSensitive
			},
		},
		{
			name:  "matcher",
			value: "CaseInsensitive",
			check: func(o Options) bool {
				return o.Matcher == CaseInsensitive
			},
		},
		{
			name:  "env",
			value: map[string]any{"testing": "true"},
			check: func(o Options) bool {
				v, found := o.Env["testing"]
				return found && v == "true"
			},
		},
		{
			name:      "env",
			value:     []string{"invalid", "input"},
			wantError: true,
			check: func(o Options) bool {
				return o.Env == nil
			},
		},
		{
			name:  "directoryFilters",
			value: []any{"-node_modules", "+project_a"},
			check: func(o Options) bool {
				return len(o.DirectoryFilters) == 2
			},
		},
		{
			name:      "directoryFilters",
			value:     []any{"invalid"},
			wantError: true,
			check: func(o Options) bool {
				return len(o.DirectoryFilters) == 0
			},
		},
		{
			name:      "directoryFilters",
			value:     []string{"-invalid", "+type"},
			wantError: true,
			check: func(o Options) bool {
				return len(o.DirectoryFilters) == 0
			},
		},
		{
			name: "annotations",
			value: map[string]any{
				"Nil":      false,
				"noBounds": true,
			},
			wantError: true,
			check: func(o Options) bool {
				return !o.Annotations[Nil] && !o.Annotations[Bounds]
			},
		},
		{
			name:      "vulncheck",
			value:     []any{"invalid"},
			wantError: true,
			check: func(o Options) bool {
				return o.Vulncheck == "" // For invalid value, default to 'off'.
			},
		},
		{
			name:  "vulncheck",
			value: "Imports",
			check: func(o Options) bool {
				return o.Vulncheck == ModeVulncheckImports // For invalid value, default to 'off'.
			},
		},
		{
			name:  "vulncheck",
			value: "imports",
			check: func(o Options) bool {
				return o.Vulncheck == ModeVulncheckImports
			},
		},
		{
			name:  "vulncheck",
			value: "Prompt",
			check: func(o Options) bool {
				return o.Vulncheck == ModeVulncheckPrompt
			},
		},
	}

	for _, test := range tests {
		var opts Options
		_, err := opts.Set(map[string]any{test.name: test.value})
		if err != nil {
			if !test.wantError {
				t.Errorf("Options.set(%q, %v) failed: %v",
					test.name, test.value, err)
			}
			continue
		} else if test.wantError {
			t.Fatalf("Options.set(%q, %v) succeeded unexpectedly",
				test.name, test.value)
		}

		// TODO: this could be made much better using cmp.Diff, if that becomes
		// available in this module.
		if !test.check(opts) {
			t.Errorf("Options.set(%q, %v): unexpected result %+v", test.name, test.value, opts)
		}
	}
}

func TestOptions_Clone(t *testing.T) {
	// Test that the Options.Clone actually performs a deep clone of the Options
	// struct.

	golden := clonetest.NonZero[*Options]()
	opts := clonetest.NonZero[*Options]()
	opts2 := opts.Clone()

	// The clone should be equivalent to the original.
	if diff := cmp.Diff(golden, opts2); diff != "" {
		t.Errorf("Clone() does not match original (-want +got):\n%s", diff)
	}

	// Mutating the clone should not mutate the original.
	clonetest.ZeroOut(opts2)
	if diff := cmp.Diff(golden, opts); diff != "" {
		t.Errorf("Mutating clone mutated the original (-want +got):\n%s", diff)
	}
}


================================================
FILE: gopls/internal/settings/staticcheck.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings

import (
	"fmt"
	"log"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/gopls/internal/protocol"
	"honnef.co/go/tools/analysis/lint"
	"honnef.co/go/tools/quickfix"
	"honnef.co/go/tools/quickfix/qf1001"
	"honnef.co/go/tools/quickfix/qf1002"
	"honnef.co/go/tools/quickfix/qf1003"
	"honnef.co/go/tools/quickfix/qf1004"
	"honnef.co/go/tools/quickfix/qf1005"
	"honnef.co/go/tools/quickfix/qf1006"
	"honnef.co/go/tools/quickfix/qf1007"
	"honnef.co/go/tools/quickfix/qf1008"
	"honnef.co/go/tools/quickfix/qf1009"
	"honnef.co/go/tools/quickfix/qf1010"
	"honnef.co/go/tools/quickfix/qf1011"
	"honnef.co/go/tools/quickfix/qf1012"
	"honnef.co/go/tools/simple"
	"honnef.co/go/tools/simple/s1000"
	"honnef.co/go/tools/simple/s1001"
	"honnef.co/go/tools/simple/s1002"
	"honnef.co/go/tools/simple/s1003"
	"honnef.co/go/tools/simple/s1004"
	"honnef.co/go/tools/simple/s1005"
	"honnef.co/go/tools/simple/s1006"
	"honnef.co/go/tools/simple/s1007"
	"honnef.co/go/tools/simple/s1008"
	"honnef.co/go/tools/simple/s1009"
	"honnef.co/go/tools/simple/s1010"
	"honnef.co/go/tools/simple/s1011"
	"honnef.co/go/tools/simple/s1012"
	"honnef.co/go/tools/simple/s1016"
	"honnef.co/go/tools/simple/s1017"
	"honnef.co/go/tools/simple/s1018"
	"honnef.co/go/tools/simple/s1019"
	"honnef.co/go/tools/simple/s1020"
	"honnef.co/go/tools/simple/s1021"
	"honnef.co/go/tools/simple/s1023"
	"honnef.co/go/tools/simple/s1024"
	"honnef.co/go/tools/simple/s1025"
	"honnef.co/go/tools/simple/s1028"
	"honnef.co/go/tools/simple/s1029"
	"honnef.co/go/tools/simple/s1030"
	"honnef.co/go/tools/simple/s1031"
	"honnef.co/go/tools/simple/s1032"
	"honnef.co/go/tools/simple/s1033"
	"honnef.co/go/tools/simple/s1034"
	"honnef.co/go/tools/simple/s1035"
	"honnef.co/go/tools/simple/s1036"
	"honnef.co/go/tools/simple/s1037"
	"honnef.co/go/tools/simple/s1038"
	"honnef.co/go/tools/simple/s1039"
	"honnef.co/go/tools/simple/s1040"
	"honnef.co/go/tools/staticcheck"
	"honnef.co/go/tools/staticcheck/sa1000"
	"honnef.co/go/tools/staticcheck/sa1001"
	"honnef.co/go/tools/staticcheck/sa1002"
	"honnef.co/go/tools/staticcheck/sa1003"
	"honnef.co/go/tools/staticcheck/sa1004"
	"honnef.co/go/tools/staticcheck/sa1005"
	"honnef.co/go/tools/staticcheck/sa1006"
	"honnef.co/go/tools/staticcheck/sa1007"
	"honnef.co/go/tools/staticcheck/sa1008"
	"honnef.co/go/tools/staticcheck/sa1010"
	"honnef.co/go/tools/staticcheck/sa1011"
	"honnef.co/go/tools/staticcheck/sa1012"
	"honnef.co/go/tools/staticcheck/sa1013"
	"honnef.co/go/tools/staticcheck/sa1014"
	"honnef.co/go/tools/staticcheck/sa1015"
	"honnef.co/go/tools/staticcheck/sa1016"
	"honnef.co/go/tools/staticcheck/sa1017"
	"honnef.co/go/tools/staticcheck/sa1018"
	"honnef.co/go/tools/staticcheck/sa1019"
	"honnef.co/go/tools/staticcheck/sa1020"
	"honnef.co/go/tools/staticcheck/sa1021"
	"honnef.co/go/tools/staticcheck/sa1023"
	"honnef.co/go/tools/staticcheck/sa1024"
	"honnef.co/go/tools/staticcheck/sa1025"
	"honnef.co/go/tools/staticcheck/sa1026"
	"honnef.co/go/tools/staticcheck/sa1027"
	"honnef.co/go/tools/staticcheck/sa1028"
	"honnef.co/go/tools/staticcheck/sa1029"
	"honnef.co/go/tools/staticcheck/sa1030"
	"honnef.co/go/tools/staticcheck/sa1031"
	"honnef.co/go/tools/staticcheck/sa1032"
	"honnef.co/go/tools/staticcheck/sa2000"
	"honnef.co/go/tools/staticcheck/sa2001"
	"honnef.co/go/tools/staticcheck/sa2002"
	"honnef.co/go/tools/staticcheck/sa2003"
	"honnef.co/go/tools/staticcheck/sa3000"
	"honnef.co/go/tools/staticcheck/sa3001"
	"honnef.co/go/tools/staticcheck/sa4000"
	"honnef.co/go/tools/staticcheck/sa4001"
	"honnef.co/go/tools/staticcheck/sa4003"
	"honnef.co/go/tools/staticcheck/sa4004"
	"honnef.co/go/tools/staticcheck/sa4005"
	"honnef.co/go/tools/staticcheck/sa4006"
	"honnef.co/go/tools/staticcheck/sa4008"
	"honnef.co/go/tools/staticcheck/sa4009"
	"honnef.co/go/tools/staticcheck/sa4010"
	"honnef.co/go/tools/staticcheck/sa4011"
	"honnef.co/go/tools/staticcheck/sa4012"
	"honnef.co/go/tools/staticcheck/sa4013"
	"honnef.co/go/tools/staticcheck/sa4014"
	"honnef.co/go/tools/staticcheck/sa4015"
	"honnef.co/go/tools/staticcheck/sa4016"
	"honnef.co/go/tools/staticcheck/sa4017"
	"honnef.co/go/tools/staticcheck/sa4018"
	"honnef.co/go/tools/staticcheck/sa4019"
	"honnef.co/go/tools/staticcheck/sa4020"
	"honnef.co/go/tools/staticcheck/sa4021"
	"honnef.co/go/tools/staticcheck/sa4022"
	"honnef.co/go/tools/staticcheck/sa4023"
	"honnef.co/go/tools/staticcheck/sa4024"
	"honnef.co/go/tools/staticcheck/sa4025"
	"honnef.co/go/tools/staticcheck/sa4026"
	"honnef.co/go/tools/staticcheck/sa4027"
	"honnef.co/go/tools/staticcheck/sa4028"
	"honnef.co/go/tools/staticcheck/sa4029"
	"honnef.co/go/tools/staticcheck/sa4030"
	"honnef.co/go/tools/staticcheck/sa4031"
	"honnef.co/go/tools/staticcheck/sa4032"
	"honnef.co/go/tools/staticcheck/sa5000"
	"honnef.co/go/tools/staticcheck/sa5001"
	"honnef.co/go/tools/staticcheck/sa5002"
	"honnef.co/go/tools/staticcheck/sa5003"
	"honnef.co/go/tools/staticcheck/sa5004"
	"honnef.co/go/tools/staticcheck/sa5005"
	"honnef.co/go/tools/staticcheck/sa5007"
	"honnef.co/go/tools/staticcheck/sa5008"
	"honnef.co/go/tools/staticcheck/sa5009"
	"honnef.co/go/tools/staticcheck/sa5010"
	"honnef.co/go/tools/staticcheck/sa5011"
	"honnef.co/go/tools/staticcheck/sa5012"
	"honnef.co/go/tools/staticcheck/sa6000"
	"honnef.co/go/tools/staticcheck/sa6001"
	"honnef.co/go/tools/staticcheck/sa6002"
	"honnef.co/go/tools/staticcheck/sa6003"
	"honnef.co/go/tools/staticcheck/sa6005"
	"honnef.co/go/tools/staticcheck/sa6006"
	"honnef.co/go/tools/staticcheck/sa9001"
	"honnef.co/go/tools/staticcheck/sa9002"
	"honnef.co/go/tools/staticcheck/sa9003"
	"honnef.co/go/tools/staticcheck/sa9004"
	"honnef.co/go/tools/staticcheck/sa9005"
	"honnef.co/go/tools/staticcheck/sa9006"
	"honnef.co/go/tools/staticcheck/sa9007"
	"honnef.co/go/tools/staticcheck/sa9008"
	"honnef.co/go/tools/staticcheck/sa9009"
	"honnef.co/go/tools/stylecheck"
	"honnef.co/go/tools/stylecheck/st1000"
	"honnef.co/go/tools/stylecheck/st1001"
	"honnef.co/go/tools/stylecheck/st1003"
	"honnef.co/go/tools/stylecheck/st1005"
	"honnef.co/go/tools/stylecheck/st1006"
	"honnef.co/go/tools/stylecheck/st1008"
	"honnef.co/go/tools/stylecheck/st1011"
	"honnef.co/go/tools/stylecheck/st1012"
	"honnef.co/go/tools/stylecheck/st1013"
	"honnef.co/go/tools/stylecheck/st1015"
	"honnef.co/go/tools/stylecheck/st1016"
	"honnef.co/go/tools/stylecheck/st1017"
	"honnef.co/go/tools/stylecheck/st1018"
	"honnef.co/go/tools/stylecheck/st1019"
	"honnef.co/go/tools/stylecheck/st1020"
	"honnef.co/go/tools/stylecheck/st1021"
	"honnef.co/go/tools/stylecheck/st1022"
	"honnef.co/go/tools/stylecheck/st1023"
)

// StaticcheckAnalyzers lists available Staticcheck analyzers.
var StaticcheckAnalyzers = initStaticcheckAnalyzers()

func initStaticcheckAnalyzers() (res []*Analyzer) {

	mapSeverity := func(severity lint.Severity) protocol.DiagnosticSeverity {
		switch severity {
		case lint.SeverityError:
			return protocol.SeverityError
		case lint.SeverityDeprecated:
			// TODO(dh): in LSP, deprecated is a tag, not a severity.
			//   We'll want to support this once we enable SA5011.
			return protocol.SeverityWarning
		case lint.SeverityWarning:
			return protocol.SeverityWarning
		case lint.SeverityInfo:
			return protocol.SeverityInformation
		case lint.SeverityHint:
			return protocol.SeverityHint
		default:
			return protocol.SeverityWarning
		}
	}

	// We can't import buildir.Analyzer directly, so grab it from another analyzer.
	buildir := sa1000.SCAnalyzer.Analyzer.Requires[0]
	if buildir.Name != "buildir" {
		panic("sa1000.Requires[0] is not buildir")
	}

	add := func(a *lint.Analyzer, dflt bool) {
		// Assert that no analyzer that requires "buildir",
		// even indirectly, is enabled by default.
		if dflt {
			var visit func(aa *analysis.Analyzer)
			visit = func(aa *analysis.Analyzer) {
				if aa == buildir {
					log.Fatalf("%s requires buildir (perhaps indirectly) yet is enabled by default", a.Analyzer.Name)
				}
				for _, req := range aa.Requires {
					visit(req)
				}
			}
			visit(a.Analyzer)
		}
		res = append(res, &Analyzer{
			analyzer:    a.Analyzer,
			staticcheck: a.Doc,
			nonDefault:  !dflt,
			severity:    mapSeverity(a.Doc.Severity),
		})
	}

	type M = map[*lint.Analyzer]any // value = true|false|nil

	addAll := func(suite string, upstream []*lint.Analyzer, config M) {
		for _, a := range upstream {
			v, ok := config[a]
			if !ok {
				panic(fmt.Sprintf("%s.Analyzers includes %s but config mapping does not; settings audit required", suite, a.Analyzer.Name))
			}
			if v != nil {
				add(a, v.(bool))
			}
		}
	}

	// For each analyzer in the four suites provided by
	// staticcheck, we provide a complete configuration, mapping
	// it to a boolean, indicating whether it should be on by
	// default in gopls, or nil to indicate explicitly that it has
	// been excluded (e.g. because it is redundant with an
	// existing vet analyzer such as printf, waitgroup, appends).
	//
	// This approach ensures that as suites grow, we make an
	// affirmative decision, positive or negative, about adding
	// new items.
	//
	// An analyzer may be off by default if:
	// - it requires, even indirectly, "buildir", which is like
	//   buildssa but uses facts, making it expensive;
	// - it has significant false positives;
	// - it reports on non-problematic style issues;
	// - its fixes are lossy (e.g. of comments) or not always sound;
	// - it reports "maybes", not "definites" (e.g. sa9001).
	// - it reports on harmless stylistic choices that may have
	//   been chosen deliberately for clarity or emphasis (e.g. s1005).
	// - it makes deductions from build tags that are not true
	//   for all configurations.

	addAll("simple", simple.Analyzers, M{
		s1000.SCAnalyzer: true,
		s1001.SCAnalyzer: true,
		s1002.SCAnalyzer: false, // makes unsound deductions from build tags
		s1003.SCAnalyzer: true,
		s1004.SCAnalyzer: true,
		s1005.SCAnalyzer: false, // not a correctness/style issue
		s1006.SCAnalyzer: false, // makes unsound deductions from build tags
		s1007.SCAnalyzer: true,
		s1008.SCAnalyzer: false, // may lose important comments
		s1009.SCAnalyzer: true,
		s1010.SCAnalyzer: true,
		s1011.SCAnalyzer: false, // requires buildir
		s1012.SCAnalyzer: true,
		s1016.SCAnalyzer: false, // may rely on coincidental structural subtyping
		s1017.SCAnalyzer: true,
		s1018.SCAnalyzer: true,
		s1019.SCAnalyzer: true,
		s1020.SCAnalyzer: true,
		s1021.SCAnalyzer: false, // may lose important comments
		s1023.SCAnalyzer: true,
		s1024.SCAnalyzer: true,
		s1025.SCAnalyzer: false, // requires buildir
		s1028.SCAnalyzer: true,
		s1029.SCAnalyzer: false, // requires buildir
		s1030.SCAnalyzer: true,  // (tentative: see docs,
		s1031.SCAnalyzer: true,
		s1032.SCAnalyzer: true,
		s1033.SCAnalyzer: true,
		s1034.SCAnalyzer: true,
		s1035.SCAnalyzer: true,
		s1036.SCAnalyzer: true,
		s1037.SCAnalyzer: true,
		s1038.SCAnalyzer: true,
		s1039.SCAnalyzer: true,
		s1040.SCAnalyzer: true,
	})

	addAll("stylecheck", stylecheck.Analyzers, M{
		// These are all slightly too opinionated to be on by default.
		st1000.SCAnalyzer: false,
		st1001.SCAnalyzer: false,
		st1003.SCAnalyzer: false,
		st1005.SCAnalyzer: false,
		st1006.SCAnalyzer: false,
		st1008.SCAnalyzer: false,
		st1011.SCAnalyzer: false,
		st1012.SCAnalyzer: false,
		st1013.SCAnalyzer: false,
		st1015.SCAnalyzer: false,
		st1016.SCAnalyzer: false,
		st1017.SCAnalyzer: false,
		st1018.SCAnalyzer: false,
		st1019.SCAnalyzer: false,
		st1020.SCAnalyzer: false,
		st1021.SCAnalyzer: false,
		st1022.SCAnalyzer: false,
		st1023.SCAnalyzer: false,
	})

	// These are not bug fixes but code transformations: some
	// reversible and value-neutral, of the kind typically listed
	// on the VS Code's Refactor/Source Action/Quick Fix menus.
	//
	// TODO(adonovan): plumb these to the appropriate menu,
	// as we do for code actions such as split/join lines.
	addAll("quickfix", quickfix.Analyzers, M{
		qf1001.SCAnalyzer: false, // not always a style improvement
		qf1002.SCAnalyzer: true,
		qf1003.SCAnalyzer: true,
		qf1004.SCAnalyzer: true,
		qf1005.SCAnalyzer: false, // not always a style improvement
		qf1006.SCAnalyzer: false, // may lose important comments
		qf1007.SCAnalyzer: false, // may lose important comments
		qf1008.SCAnalyzer: false, // not always a style improvement
		qf1009.SCAnalyzer: true,
		qf1010.SCAnalyzer: true,
		qf1011.SCAnalyzer: false, // not always a style improvement
		qf1012.SCAnalyzer: true,
	})

	addAll("staticcheck", staticcheck.Analyzers, M{
		sa1000.SCAnalyzer: false, // requires buildir
		sa1001.SCAnalyzer: true,
		sa1002.SCAnalyzer: false, // requires buildir
		sa1003.SCAnalyzer: false, // requires buildir
		sa1004.SCAnalyzer: true,
		sa1005.SCAnalyzer: true,
		sa1006.SCAnalyzer: nil,   // redundant wrt 'printf'
		sa1007.SCAnalyzer: false, // requires buildir
		sa1008.SCAnalyzer: true,
		sa1010.SCAnalyzer: false, // requires buildir
		sa1011.SCAnalyzer: false, // requires buildir
		sa1012.SCAnalyzer: true,
		sa1013.SCAnalyzer: true,
		sa1014.SCAnalyzer: false, // requires buildir
		sa1015.SCAnalyzer: false, // requires buildir
		sa1016.SCAnalyzer: true,
		sa1017.SCAnalyzer: false, // requires buildir
		sa1018.SCAnalyzer: false, // requires buildir
		sa1019.SCAnalyzer: nil,   // redundant wrt 'deprecated'
		sa1020.SCAnalyzer: false, // requires buildir
		sa1021.SCAnalyzer: false, // requires buildir
		sa1023.SCAnalyzer: false, // requires buildir
		sa1024.SCAnalyzer: false, // requires buildir
		sa1025.SCAnalyzer: false, // requires buildir
		sa1026.SCAnalyzer: false, // requires buildir
		sa1027.SCAnalyzer: false, // requires buildir
		sa1028.SCAnalyzer: false, // requires buildir
		sa1029.SCAnalyzer: false, // requires buildir
		sa1030.SCAnalyzer: false, // requires buildir
		sa1031.SCAnalyzer: false, // requires buildir
		sa1032.SCAnalyzer: false, // requires buildir
		sa2000.SCAnalyzer: nil,   // redundant wrt 'waitgroup'
		sa2001.SCAnalyzer: true,
		sa2002.SCAnalyzer: false, // requires buildir
		sa2003.SCAnalyzer: false, // requires buildir
		sa3000.SCAnalyzer: true,
		sa3001.SCAnalyzer: true,
		sa4000.SCAnalyzer: true,
		sa4001.SCAnalyzer: true,
		sa4003.SCAnalyzer: true,
		sa4004.SCAnalyzer: true,
		sa4005.SCAnalyzer: false, // requires buildir
		sa4006.SCAnalyzer: false, // requires buildir
		sa4008.SCAnalyzer: false, // requires buildir
		sa4009.SCAnalyzer: false, // requires buildir
		sa4010.SCAnalyzer: false, // requires buildir
		sa4011.SCAnalyzer: true,
		sa4012.SCAnalyzer: false, // requires buildir
		sa4013.SCAnalyzer: true,
		sa4014.SCAnalyzer: true,
		sa4015.SCAnalyzer: false, // requires buildir
		sa4016.SCAnalyzer: true,
		sa4017.SCAnalyzer: false, // requires buildir
		sa4018.SCAnalyzer: false, // requires buildir
		sa4019.SCAnalyzer: true,
		sa4020.SCAnalyzer: true,
		sa4021.SCAnalyzer: nil, // redundant wrt 'appends'
		sa4022.SCAnalyzer: true,
		sa4023.SCAnalyzer: false, // requires buildir
		sa4024.SCAnalyzer: true,
		sa4025.SCAnalyzer: true,
		sa4026.SCAnalyzer: true,
		sa4027.SCAnalyzer: true,
		sa4028.SCAnalyzer: true,
		sa4029.SCAnalyzer: true,
		sa4030.SCAnalyzer: true,
		sa4031.SCAnalyzer: false, // requires buildir
		sa4032.SCAnalyzer: true,
		sa5000.SCAnalyzer: false, // requires buildir
		sa5001.SCAnalyzer: true,
		sa5002.SCAnalyzer: false, // makes unsound deductions from build tags
		sa5003.SCAnalyzer: true,
		sa5004.SCAnalyzer: true,
		sa5005.SCAnalyzer: false, // requires buildir
		sa5007.SCAnalyzer: false, // requires buildir
		sa5008.SCAnalyzer: true,
		sa5009.SCAnalyzer: nil,   // requires buildir; redundant wrt 'printf' (#34494)
		sa5010.SCAnalyzer: false, // requires buildir
		sa5011.SCAnalyzer: false, // requires buildir
		sa5012.SCAnalyzer: false, // requires buildir
		sa6000.SCAnalyzer: false, // requires buildir
		sa6001.SCAnalyzer: false, // requires buildir
		sa6002.SCAnalyzer: false, // requires buildir
		sa6003.SCAnalyzer: false, // requires buildir
		sa6005.SCAnalyzer: true,
		sa6006.SCAnalyzer: true,
		sa9001.SCAnalyzer: false, // reports a "maybe" bug (low signal/noise)
		sa9002.SCAnalyzer: true,
		sa9003.SCAnalyzer: false, // requires buildir; NonDefault
		sa9004.SCAnalyzer: true,
		sa9005.SCAnalyzer: false, // requires buildir
		sa9006.SCAnalyzer: true,
		sa9007.SCAnalyzer: false, // requires buildir
		sa9008.SCAnalyzer: false, // requires buildir
		sa9009.SCAnalyzer: true,
	})

	return res
}


================================================
FILE: gopls/internal/settings/vet_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package settings_test

import (
	"encoding/json"
	"fmt"
	"os/exec"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/doc"
	"golang.org/x/tools/internal/testenv"
)

// TestVetSuite ensures that gopls's analyser suite is a superset of vet's.
//
// This test may fail spuriously if gopls/doc/generate.TestGenerated
// fails. In that case retry after re-running the JSON generator.
func TestVetSuite(t *testing.T) {
	testenv.NeedsTool(t, "go")

	// Read gopls' suite from the API JSON.
	goplsAnalyzers := make(map[string]bool)
	var api doc.API
	if err := json.Unmarshal([]byte(doc.JSON), &api); err != nil {
		t.Fatal(err)
	}
	for _, a := range api.Analyzers {
		goplsAnalyzers[a.Name] = true
	}

	// Read vet's suite by parsing its help message.
	cmd := exec.Command("go", "tool", "vet", "help")
	cmd.Stdout = new(strings.Builder)
	if err := cmd.Run(); err != nil {
		t.Fatalf("failed to run vet: %v", err)
	}
	out := fmt.Sprint(cmd.Stdout)
	_, out, _ = strings.Cut(out, "Registered analyzers:\n\n")
	out, _, _ = strings.Cut(out, "\n\n")
	for line := range strings.SplitSeq(out, "\n") {
		name := strings.Fields(line)[0]
		if !goplsAnalyzers[name] {
			t.Errorf("gopls lacks vet analyzer %q", name)
		}
	}
}


================================================
FILE: gopls/internal/telemetry/counterpath.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package telemetry

import "strings"

// A CounterPath represents the components of a telemetry counter name.
//
// By convention, counter names follow the format path/to/counter:bucket. The
// CounterPath holds the '/'-separated components of this path, along with a
// final element representing the bucket.
//
// CounterPaths may be used to build up counters incrementally, such as when a
// set of observed counters shared a common prefix, to be controlled by the
// caller.
type CounterPath []string

// FullName returns the counter name for the receiver.
func (p CounterPath) FullName() string {
	if len(p) == 0 {
		return ""
	}
	name := strings.Join([]string(p[:len(p)-1]), "/")
	if bucket := p[len(p)-1]; bucket != "" {
		name += ":" + bucket
	}
	return name
}


================================================
FILE: gopls/internal/telemetry/counterpath_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package telemetry

import (
	"testing"
)

// TestCounterPath tests the formatting of various counter paths.
func TestCounterPath(t *testing.T) {
	tests := []struct {
		path CounterPath
		want string
	}{
		{
			path: CounterPath{},
			want: "",
		},
		{
			path: CounterPath{"counter"},
			want: ":counter",
		},
		{
			path: CounterPath{"counter", "bucket"},
			want: "counter:bucket",
		},
		{
			path: CounterPath{"path", "to", "counter"},
			want: "path/to:counter",
		},
		{
			path: CounterPath{"multi", "component", "path", "bucket"},
			want: "multi/component/path:bucket",
		},
		{
			path: CounterPath{"path", ""},
			want: "path",
		},
	}
	for _, tt := range tests {
		if got := tt.path.FullName(); got != tt.want {
			t.Errorf("CounterPath(%v).FullName() = %v, want %v", tt.path, got, tt.want)
		}
	}
}


================================================
FILE: gopls/internal/telemetry/latency.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package telemetry

import (
	"context"
	"errors"
	"fmt"
	"sort"
	"sync"
	"time"

	"golang.org/x/telemetry/counter"
)

// latencyKey is used for looking up latency counters.
type latencyKey struct {
	operation, bucket string
	isError           bool
}

var (
	latencyBuckets = []struct {
		end  time.Duration
		name string
	}{
		{10 * time.Millisecond, "<10ms"},
		{50 * time.Millisecond, "<50ms"},
		{100 * time.Millisecond, "<100ms"},
		{200 * time.Millisecond, "<200ms"},
		{500 * time.Millisecond, "<500ms"},
		{1 * time.Second, "<1s"},
		{5 * time.Second, "<5s"},
		{24 * time.Hour, "<24h"},
	}

	latencyCounterMu sync.Mutex
	latencyCounters  = make(map[latencyKey]*counter.Counter) // lazily populated
)

// ForEachLatencyCounter runs the provided function for each current latency
// counter measuring the given operation.
//
// Exported for testing.
func ForEachLatencyCounter(operation string, isError bool, f func(*counter.Counter)) {
	latencyCounterMu.Lock()
	defer latencyCounterMu.Unlock()

	for k, v := range latencyCounters {
		if k.operation == operation && k.isError == isError {
			f(v)
		}
	}
}

// getLatencyCounter returns the counter used to record latency of the given
// operation in the given bucket.
func getLatencyCounter(operation, bucket string, isError bool) *counter.Counter {
	latencyCounterMu.Lock()
	defer latencyCounterMu.Unlock()

	key := latencyKey{operation, bucket, isError}
	c, ok := latencyCounters[key]
	if !ok {
		var name string
		if isError {
			name = fmt.Sprintf("gopls/%s/error-latency:%s", operation, bucket)
		} else {
			name = fmt.Sprintf("gopls/%s/latency:%s", operation, bucket)
		}
		c = counter.New(name)
		latencyCounters[key] = c
	}
	return c
}

// StartLatencyTimer starts a timer for the gopls operation with the given
// name, and returns a func to stop the timer and record the latency sample.
//
// If the context provided to the resulting func is done, no observation is
// recorded.
func StartLatencyTimer(operation string) func(context.Context, error) {
	start := time.Now()
	return func(ctx context.Context, err error) {
		if errors.Is(ctx.Err(), context.Canceled) {
			// Ignore timing where the operation is cancelled, it may be influenced
			// by client behavior.
			return
		}
		latency := time.Since(start)
		bucketIdx := sort.Search(len(latencyBuckets), func(i int) bool {
			bucket := latencyBuckets[i]
			return latency < bucket.end
		})
		if bucketIdx < len(latencyBuckets) { // ignore latency longer than a day :)
			bucketName := latencyBuckets[bucketIdx].name
			getLatencyCounter(operation, bucketName, err != nil).Inc()
		}
	}
}


================================================
FILE: gopls/internal/telemetry/telemetry_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.21 && !openbsd && !js && !wasip1 && !solaris && !android && !386

package telemetry_test

import (
	"context"
	"errors"
	"os"
	"strconv"
	"strings"
	"testing"
	"time"

	"golang.org/x/telemetry/counter"
	"golang.org/x/telemetry/counter/countertest" // requires go1.21+
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/telemetry"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	tmp, err := os.MkdirTemp("", "gopls-telemetry-test-counters")
	if err != nil {
		panic(err)
	}
	countertest.Open(tmp)
	code := Main(m)
	os.RemoveAll(tmp) // ignore error (cleanup fails on Windows; golang/go#68243)
	os.Exit(code)
}

func TestTelemetry(t *testing.T) {
	var (
		goversion = ""
		editor    = "vscode" // We set ClientName("Visual Studio Code") below.
	)

	// Run gopls once to determine the Go version.
	WithOptions(
		Modes(Default),
	).Run(t, "", func(_ *testing.T, env *Env) {
		goversion = strconv.Itoa(env.GoVersion())
	})

	// counters that should be incremented once per session
	sessionCounters := []*counter.Counter{
		counter.New("gopls/client:" + editor),
		counter.New("gopls/goversion:1." + goversion),
		counter.New("fwd/vscode/linter:a"),
		counter.New("gopls/gotoolchain:local"),
	}
	initialCounts := make([]uint64, len(sessionCounters))
	for i, c := range sessionCounters {
		count, err := countertest.ReadCounter(c)
		if err != nil {
			continue // counter db not open, or counter not found
		}
		initialCounts[i] = count
	}

	// Verify that a properly configured session gets notified of a bug on the
	// server.
	WithOptions(
		Modes(Default), // must be in-process to receive the bug report below
		Settings{"showBugReports": true},
		ClientName("Visual Studio Code"),
		EnvVars{
			"GOTOOLCHAIN": "local", // so that the local counter is incremented
		},
	).Run(t, "", func(_ *testing.T, env *Env) {
		goversion = strconv.Itoa(env.GoVersion())
		addForwardedCounters(env, []string{"vscode/linter:a"}, []int64{1})
		const desc = "got a bug"

		// This will increment a counter named something like:
		//
		// `gopls/bug
		// golang.org/x/tools/gopls/internal/util/bug.report:+35
		// golang.org/x/tools/gopls/internal/util/bug.Report:=68
		// golang.org/x/tools/gopls/internal/telemetry_test.TestTelemetry.func2:+4
		// golang.org/x/tools/gopls/internal/test/integration.(*Runner).Run.func1:+87
		// testing.tRunner:+150
		// runtime.goexit:+0`
		//
		bug.Report(desc) // want a stack counter with the trace starting from here.

		env.Await(ShownMessage(desc))
	})

	// gopls/editor:client
	// gopls/goversion:1.x
	// fwd/vscode/linter:a
	// gopls/gotoolchain:local
	for i, c := range sessionCounters {
		want := initialCounts[i] + 1
		got, err := countertest.ReadCounter(c)
		if err != nil || got != want {
			t.Errorf("ReadCounter(%q) = (%v, %v), want (%v, nil)", c.Name(), got, err, want)
			t.Logf("Current timestamp = %v", time.Now().UTC())
		}
	}

	// gopls/bug
	bugcount := bug.BugReportCount
	counts, err := countertest.ReadStackCounter(bugcount)
	if err != nil {
		t.Fatalf("ReadStackCounter(bugreportcount) failed - %v", err)
	}
	if len(counts) != 1 || !hasEntry(counts, t.Name(), 1) {
		t.Errorf("read stackcounter(%q) = (%#v, %v), want one entry", "gopls/bug", counts, err)
		t.Logf("Current timestamp = %v", time.Now().UTC())
	}
}

func TestSettingTelemetry(t *testing.T) {
	// counters that should be incremented by each session
	sessionCounters := []*counter.Counter{
		counter.New("gopls/setting/diagnosticsDelay"),
		counter.New("gopls/setting/staticcheck:true"),
		counter.New("gopls/setting/noSemanticString:true"),
		counter.New("gopls/setting/analyses/deprecated:false"),
	}

	initialCounts := make([]uint64, len(sessionCounters))
	for i, c := range sessionCounters {
		count, err := countertest.ReadCounter(c)
		if err != nil {
			continue // counter db not open, or counter not found
		}
		initialCounts[i] = count
	}

	// Run gopls.
	WithOptions(
		Modes(Default),
		Settings{
			"staticcheck": true,
			"analyses": map[string]bool{
				"deprecated": false,
			},
			"diagnosticsDelay": "0s",
			"noSemanticString": true,
		},
	).Run(t, "", func(_ *testing.T, env *Env) {
	})

	for i, c := range sessionCounters {
		count, err := countertest.ReadCounter(c)
		if err != nil {
			t.Errorf("ReadCounter(%q) failed: %v", c.Name(), err)
			continue
		}
		if count <= initialCounts[i] {
			t.Errorf("ReadCounter(%q) = %d, want > %d", c.Name(), count, initialCounts[i])
		}
	}
}

func addForwardedCounters(env *Env, names []string, values []int64) {
	args, err := command.MarshalArgs(command.AddTelemetryCountersArgs{
		Names: names, Values: values,
	})
	if err != nil {
		env.TB.Fatal(err)
	}
	var res error
	env.ExecuteCommand(&protocol.ExecuteCommandParams{
		Command:   command.AddTelemetryCounters.String(),
		Arguments: args,
	}, &res)
	if res != nil {
		env.TB.Errorf("%v failed - %v", command.AddTelemetryCounters, res)
	}
}

func hasEntry(counts map[string]uint64, pattern string, want uint64) bool {
	for k, v := range counts {
		if strings.Contains(k, pattern) && v == want {
			return true
		}
	}
	return false
}

func TestLatencyCounter(t *testing.T) {
	const operation = "TestLatencyCounter" // a unique operation name

	stop := telemetry.StartLatencyTimer(operation)
	stop(context.Background(), nil)

	for isError, want := range map[bool]uint64{false: 1, true: 0} {
		if got := totalLatencySamples(t, operation, isError); got != want {
			t.Errorf("totalLatencySamples(operation=%v, isError=%v) = %d, want %d", operation, isError, got, want)
		}
	}
}

func TestLatencyCounter_Error(t *testing.T) {
	const operation = "TestLatencyCounter_Error" // a unique operation name

	stop := telemetry.StartLatencyTimer(operation)
	stop(context.Background(), errors.New("bad"))

	for isError, want := range map[bool]uint64{false: 0, true: 1} {
		if got := totalLatencySamples(t, operation, isError); got != want {
			t.Errorf("totalLatencySamples(operation=%v, isError=%v) = %d, want %d", operation, isError, got, want)
		}
	}
}

func TestLatencyCounter_Cancellation(t *testing.T) {
	const operation = "TestLatencyCounter_Cancellation"

	stop := telemetry.StartLatencyTimer(operation)
	ctx, cancel := context.WithCancel(context.Background())
	cancel()
	stop(ctx, nil)

	for isError, want := range map[bool]uint64{false: 0, true: 0} {
		if got := totalLatencySamples(t, operation, isError); got != want {
			t.Errorf("totalLatencySamples(operation=%v, isError=%v) = %d, want %d", operation, isError, got, want)
		}
	}
}

func totalLatencySamples(t *testing.T, operation string, isError bool) uint64 {
	var total uint64
	telemetry.ForEachLatencyCounter(operation, isError, func(c *counter.Counter) {
		count, err := countertest.ReadCounter(c)
		if err != nil {
			t.Errorf("ReadCounter(%s) failed: %v", c.Name(), err)
		} else {
			total += count
		}
	})
	return total
}

func TestLatencyInstrumentation(t *testing.T) {
	const files = `
-- go.mod --
module mod.test/a
go 1.18
-- a.go --
package a

func _() {
	x := 0
	_ = x
}
`

	// Verify that a properly configured session gets notified of a bug on the
	// server.
	WithOptions(
		Modes(Default), // must be in-process to receive the bug report below
	).Run(t, files, func(_ *testing.T, env *Env) {
		env.OpenFile("a.go")
		before := totalLatencySamples(t, "completion", false)
		loc := env.RegexpSearch("a.go", "()x")
		for i := 0; i < 10; i++ {
			env.Completion(loc)
		}
		after := totalLatencySamples(t, "completion", false)
		if after-before < 10 {
			t.Errorf("after 10 completions, completion counter went from %d to %d", before, after)
		}
	})
}


================================================
FILE: gopls/internal/template/completion.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"bytes"
	"context"
	"fmt"
	"go/scanner"
	gotoken "go/token"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

// information needed for completion
type completer struct {
	p      *parsed
	pos    protocol.Position
	offset int // offset of the start of the Token
	ctx    protocol.CompletionContext
	syms   map[string]symbol
}

func Completion(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, pos protocol.Position, context protocol.CompletionContext) (*protocol.CompletionList, error) {
	all := parseSet(snapshot.Templates())
	var start int // the beginning of the Token (completed or not)
	syms := make(map[string]symbol)
	var p *parsed
	for uri, fc := range all.files {
		// collect symbols from all template files
		filterSyms(syms, fc.symbols)
		if uri.Path() != fh.URI().Path() {
			continue
		}
		offset, err := enclosingTokenStart(fc, pos)
		if err != nil {
			return nil, err
		}
		start = offset
		p = fc
	}
	if p == nil {
		// this cannot happen unless the search missed a template file
		return nil, fmt.Errorf("%s not found", fh.Identity().URI.Path())
	}
	c := completer{
		p:      p,
		pos:    pos,
		offset: start + len(lbraces),
		ctx:    context,
		syms:   syms,
	}
	return c.complete()
}

func filterSyms(syms map[string]symbol, ns []symbol) {
	for _, xsym := range ns {
		switch xsym.kind {
		case protocol.Method, protocol.Package, protocol.Boolean, protocol.Namespace,
			protocol.Function:
			syms[xsym.name] = xsym // we don't care which symbol we get
		case protocol.Variable:
			if xsym.name != "dot" {
				syms[xsym.name] = xsym
			}
		case protocol.Constant:
			if xsym.name == "nil" {
				syms[xsym.name] = xsym
			}
		}
	}
}

// enclosingTokenStart returns the start offset of the enclosing token.
// A (-1, non-nil) result indicates "no enclosing token".
func enclosingTokenStart(fc *parsed, pos protocol.Position) (int, error) {
	// pos is the pos-th character. if the cursor is at the beginning
	// of the file, pos is 0. That is, we've only seen characters before pos
	// 1. pos might be in a Token, return tk.Start
	// 2. pos might be after an elided but before a Token, return elided
	// 3. return -1 for false
	offset, err := fc.mapper.PositionOffset(pos)
	if err != nil {
		return 0, err
	}

	// TODO: opt: this could be a binary search, as the tokens are ordered
	for _, tk := range fc.tokens {
		if tk.start+len(lbraces) <= offset && offset+len(rbraces) <= tk.end {
			return tk.start, nil
		}
	}

	for _, x := range fc.elided {
		if x+len(lbraces) > offset {
			// fc.elided is sorted, and x is the position where a '{{' was replaced
			// by '  '. We consider only cases where the replaced {{ is to the left
			// of the cursor.
			break
		}
		// If the interval [x,offset] does not contain Left or Right
		// then provide completions. (do we need the test for Right?)
		if !bytes.Contains(fc.buf[x:offset], lbraces) && !bytes.Contains(fc.buf[x:offset], rbraces) {
			return x, nil
		}
	}
	return -1, fmt.Errorf("no token enclosing %d", pos)
}

var (
	keywords = []string{"if", "with", "else", "block", "range", "template", "end}}", "end"}
	globals  = []string{"and", "call", "html", "index", "slice", "js", "len", "not", "or",
		"urlquery", "printf", "println", "print", "eq", "ne", "le", "lt", "ge", "gt"}
)

// find the completions. start is the offset of either the Token enclosing pos, or where
// the incomplete token starts.
// The error return is always nil.
func (c *completer) complete() (*protocol.CompletionList, error) {
	ans := &protocol.CompletionList{IsIncomplete: true, Items: []protocol.CompletionItem{}}
	start, err := c.p.mapper.PositionOffset(c.pos)
	if err != nil {
		return ans, err
	}
	sofar := c.p.buf[c.offset:start]
	if len(sofar) == 0 || sofar[len(sofar)-1] == ' ' || sofar[len(sofar)-1] == '\t' {
		return ans, nil
	}
	// sofar could be parsed by either c.analyzer() or scan(). The latter is precise
	// and slower, but fast enough
	words := scan(sofar)
	// 1. if pattern starts $, show variables
	// 2. if pattern starts ., show methods (and . by itself?)
	// 3. if len(words) == 1, show firstWords (but if it were a |, show functions and globals)
	// 4. ...? (parenthetical expressions, arguments, ...) (packages, namespaces, nil?)
	if len(words) == 0 {
		return nil, nil // if this happens, why were we called?
	}
	pattern := words[len(words)-1]
	if pattern[0] == '$' {
		// should we also return a raw "$"?
		for _, s := range c.syms {
			if s.kind == protocol.Variable && weakMatch(s.name, pattern) > 0 {
				ans.Items = append(ans.Items, protocol.CompletionItem{
					Label:  s.name,
					Kind:   protocol.VariableCompletion,
					Detail: "Variable",
				})
			}
		}
		return ans, nil
	}
	if pattern[0] == '.' {
		for _, s := range c.syms {
			if s.kind == protocol.Method && weakMatch("."+s.name, pattern) > 0 {
				ans.Items = append(ans.Items, protocol.CompletionItem{
					Label:  s.name,
					Kind:   protocol.MethodCompletion,
					Detail: "Method/member",
				})
			}
		}
		return ans, nil
	}
	// could we get completion attempts in strings or numbers, and if so, do we care?
	// globals
	for _, kw := range globals {
		if weakMatch(kw, pattern) != 0 {
			ans.Items = append(ans.Items, protocol.CompletionItem{
				Label:  kw,
				Kind:   protocol.KeywordCompletion,
				Detail: "Function",
			})
		}
	}
	// and functions
	for _, s := range c.syms {
		if s.kind == protocol.Function && weakMatch(s.name, pattern) != 0 {
			ans.Items = append(ans.Items, protocol.CompletionItem{
				Label:  s.name,
				Kind:   protocol.FunctionCompletion,
				Detail: "Function",
			})
		}
	}
	// keywords if we're at the beginning
	if len(words) <= 1 || len(words[len(words)-2]) == 1 && words[len(words)-2][0] == '|' {
		for _, kw := range keywords {
			if weakMatch(kw, pattern) != 0 {
				ans.Items = append(ans.Items, protocol.CompletionItem{
					Label:  kw,
					Kind:   protocol.KeywordCompletion,
					Detail: "keyword",
				})
			}
		}
	}
	return ans, nil
}

// version of c.analyze that uses go/scanner.
func scan(buf []byte) []string {
	fset := gotoken.NewFileSet()
	fp := fset.AddFile("", -1, len(buf))
	var sc scanner.Scanner
	sc.Init(fp, buf, func(pos gotoken.Position, msg string) {}, scanner.ScanComments)
	ans := make([]string, 0, 10) // preallocating gives a measurable savings
	for {
		_, tok, lit := sc.Scan() // tok is an int
		if tok == gotoken.EOF {
			break // done
		} else if tok == gotoken.SEMICOLON && lit == "\n" {
			continue // don't care, but probably can't happen
		} else if tok == gotoken.PERIOD {
			ans = append(ans, ".") // lit is empty
		} else if tok == gotoken.IDENT && len(ans) > 0 && ans[len(ans)-1] == "." {
			ans[len(ans)-1] = "." + lit
		} else if tok == gotoken.IDENT && len(ans) > 0 && ans[len(ans)-1] == "$" {
			ans[len(ans)-1] = "$" + lit
		} else if lit != "" {
			ans = append(ans, lit)
		}
	}
	return ans
}

// pattern is what the user has typed
func weakMatch(choice, pattern string) float64 {
	lower := strings.ToLower(choice)
	// for now, use only lower-case everywhere
	pattern = strings.ToLower(pattern)
	// The first char has to match
	if pattern[0] != lower[0] {
		return 0
	}
	// If they start with ., then the second char has to match
	from := 1
	if pattern[0] == '.' {
		if len(pattern) < 2 {
			return 1 // pattern just a ., so it matches
		}
		if pattern[1] != lower[1] {
			return 0
		}
		from = 2
	}
	// check that all the characters of pattern occur as a subsequence of choice
	i, j := from, from
	for ; i < len(lower) && j < len(pattern); j++ {
		if pattern[j] == lower[i] {
			i++
			if i >= len(lower) {
				return 0
			}
		}
	}
	if j < len(pattern) {
		return 0
	}
	return 1
}


================================================
FILE: gopls/internal/template/completion_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"log"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

func init() {
	log.SetFlags(log.Lshortfile)
}

type tparse struct {
	marked string   // ^ shows where to ask for completions. (The user just typed the following character.)
	wanted []string // expected completions; nil => no enclosing token
}

// Test completions in templates that parse enough (if completion needs symbols)
// Seen characters up to the ^
func TestParsed(t *testing.T) {
	for _, test := range []tparse{
		{"{{x}}{{12. xx^", nil}, // https://github.com/golang/go/issues/50430
		{`<table class="chroma" data-new-comment-url="{{if $.PageIsPullFiles}}{{$.Issue.HTMLURL}}/files/reviews/new_comment{{else}}{{$.CommitHTML}}/new_comment^{{end}}">`, nil},
		{"{{i^f}}", []string{"index", "if"}},
		{"{{if .}}{{e^ {{end}}", []string{"eq", "end}}", "else", "end"}},
		{"{{foo}}{{f^", []string{"foo"}},
		{"{{$^}}", []string{"$"}},
		{"{{$x:=4}}{{$^", []string{"$x"}},
		{"{{$x:=4}}{{$ ^ ", []string{}},
		{"{{len .Modified}}{{.^Mo", []string{"Modified"}},
		{"{{len .Modified}}{{.mf^", []string{"Modified"}},
		{"{{$^ }}", []string{"$"}},
		{"{{$a =3}}{{$^", []string{"$a"}},
		// .two is not good here: fix someday
		{`{{.Modified}}{{.^{{if $.one.two}}xxx{{end}}`, []string{"Modified", "one", "two"}},
		{`{{.Modified}}{{.o^{{if $.one.two}}xxx{{end}}`, []string{"one"}},
		{"{{.Modiifed}}{{.one.t^{{if $.one.two}}xxx{{end}}", []string{"two"}},
		{`{{block "foo" .}}{{i^`, []string{"index", "if"}},
		{"{{in^{{Internal}}", []string{"index", "Internal", "if"}},
		// simple number has no completions
		{"{{4^e", []string{}},
		// simple string has no completions
		{"{{`e^", []string{}},
		{"{{`No i^", []string{}}, // example of why go/scanner is used
		{"{{xavier}}{{12. x^", []string{"xavier"}},
	} {
		t.Run("", func(t *testing.T) {
			var got []string
			if c := testCompleter(t, test); c != nil {
				ans, _ := c.complete()
				for _, a := range ans.Items {
					got = append(got, a.Label)
				}
			}
			if len(got) != len(test.wanted) {
				t.Fatalf("%q: got %q, wanted %q %d,%d", test.marked, got, test.wanted, len(got), len(test.wanted))
			}
			sort.Strings(test.wanted)
			sort.Strings(got)
			for i := 0; i < len(got); i++ {
				if test.wanted[i] != got[i] {
					t.Fatalf("%q at %d: got %v, wanted %v", test.marked, i, got, test.wanted)
				}
			}
		})
	}
}

func testCompleter(t *testing.T, tx tparse) *completer {
	// seen chars up to ^
	offset := strings.Index(tx.marked, "^")
	buf := strings.Replace(tx.marked, "^", "", 1)
	p := parseBuffer("", []byte(buf))
	if p.parseErr != nil {
		t.Logf("%q: %v", tx.marked, p.parseErr)
	}
	pos, err := p.mapper.OffsetPosition(offset)
	if err != nil {
		t.Fatal(err)
	}

	start, err := enclosingTokenStart(p, pos)
	if err != nil {
		if start == -1 {
			return nil // no enclosing token
		}
		t.Fatal(err)
	}
	syms := make(map[string]symbol)
	filterSyms(syms, p.symbols)
	return &completer{
		p:      p,
		pos:    pos,
		offset: start + len(lbraces),
		ctx:    protocol.CompletionContext{TriggerKind: protocol.Invoked},
		syms:   syms,
	}
}


================================================
FILE: gopls/internal/template/highlight.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"context"
	"fmt"
	"regexp"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

func Highlight(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.DocumentHighlight, error) {
	buf, err := fh.Content()
	if err != nil {
		return nil, err
	}
	p := parseBuffer(fh.URI(), buf)
	start, end, err := p.mapper.RangeOffsets(rng)
	if err != nil {
		return nil, err
	}

	if p.parseErr == nil {
		for _, s := range p.symbols {
			if s.start <= start && end < s.start+s.len {
				return markSymbols(p, s)
			}
		}
	}

	// these tokens exist whether or not there was a parse error
	// (symbols require a successful parse)
	for _, tok := range p.tokens {
		if tok.start <= start && end < tok.end {
			wordAt := wordAt(p.buf, start)
			if len(wordAt) > 0 {
				return markWordInToken(p, wordAt)
			}
		}
	}

	// TODO: find the 'word' at pos, etc: someday
	// until then we get the default action, which doesn't respect word boundaries
	return nil, nil
}

func markSymbols(p *parsed, sym symbol) ([]protocol.DocumentHighlight, error) {
	var ans []protocol.DocumentHighlight
	for _, s := range p.symbols {
		if s.name == sym.name {
			kind := protocol.Read
			if s.vardef {
				kind = protocol.Write
			}
			rng, err := p.mapper.OffsetRange(s.offsets())
			if err != nil {
				return nil, err
			}
			ans = append(ans, protocol.DocumentHighlight{
				Range: rng,
				Kind:  kind,
			})
		}
	}
	return ans, nil
}

// A token is {{...}}, and this marks words in the token that equal the give word
func markWordInToken(p *parsed, wordAt string) ([]protocol.DocumentHighlight, error) {
	var ans []protocol.DocumentHighlight
	pat, err := regexp.Compile(fmt.Sprintf(`\b%s\b`, wordAt))
	if err != nil {
		return nil, fmt.Errorf("%q: unmatchable word (%v)", wordAt, err)
	}
	for _, tok := range p.tokens {
		matches := pat.FindAllIndex(p.buf[tok.start:tok.end], -1)
		for _, match := range matches {
			rng, err := p.mapper.OffsetRange(match[0], match[1])
			if err != nil {
				return nil, err
			}
			ans = append(ans, protocol.DocumentHighlight{
				Range: rng,
				Kind:  protocol.Text,
			})
		}
	}
	return ans, nil
}

// wordAt returns the word the cursor is in (meaning in or just before)
func wordAt(buf []byte, pos int) string {
	if pos >= len(buf) {
		return ""
	}
	after := moreRe.Find(buf[pos:])
	if len(after) == 0 {
		return "" // end of the word
	}
	got := wordRe.Find(buf[:pos+len(after)])
	return string(got)
}

var (
	wordRe = regexp.MustCompile(`[$]?\w+$`)
	moreRe = regexp.MustCompile(`^[$]?\w+`)
)


================================================
FILE: gopls/internal/template/implementations.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"context"
	"fmt"
	"regexp"
	"strconv"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/semtok"
)

// line number (1-based) and message
var errRe = regexp.MustCompile(`template.*:(\d+): (.*)`)

// Diagnostics returns parse errors. There is only one per file.
// The errors are not always helpful. For instance { {end}}
// will likely point to the end of the file.
func Diagnostics(snapshot *cache.Snapshot) map[protocol.DocumentURI][]*cache.Diagnostic {
	diags := make(map[protocol.DocumentURI][]*cache.Diagnostic)
	for uri, fh := range snapshot.Templates() {
		diags[uri] = diagnoseOne(fh)
	}
	return diags
}

func diagnoseOne(fh file.Handle) []*cache.Diagnostic {
	// no need for skipTemplate check, as Diagnose is called on the
	// snapshot's template files
	buf, err := fh.Content()
	if err != nil {
		// TODO: Is a Diagnostic with no Range useful? event.Error also?
		msg := fmt.Sprintf("failed to read %s (%v)", fh.URI().Path(), err)
		return []*cache.Diagnostic{{
			Message:  msg,
			Severity: protocol.SeverityError,
			URI:      fh.URI(),
			Source:   cache.TemplateError,
		}}
	}
	p := parseBuffer(fh.URI(), buf)
	if p.parseErr == nil {
		return nil
	}

	errorf := func(format string, args ...any) []*cache.Diagnostic {
		msg := fmt.Sprintf("malformed template error %q: %s",
			p.parseErr.Error(),
			fmt.Sprintf(format, args...))
		rng, err := p.mapper.OffsetRange(0, 1) // first UTF-16 code
		if err != nil {
			rng = protocol.Range{} // start of file
		}
		return []*cache.Diagnostic{{
			Message:  msg,
			Severity: protocol.SeverityError,
			Range:    rng,
			URI:      fh.URI(),
			Source:   cache.TemplateError,
		}}
	}

	// errors look like `template: :40: unexpected "}" in operand`
	// so the string needs to be parsed
	matches := errRe.FindStringSubmatch(p.parseErr.Error())
	if len(matches) != 3 {
		return errorf("expected 3 matches, got %d (%v)", len(matches), matches)
	}
	lineno, err := strconv.Atoi(matches[1])
	if err != nil {
		return errorf("couldn't convert %q to int, %v", matches[1], err)
	}
	msg := matches[2]

	// Compute the range for the whole (1-based) line.
	rng, err := lineRange(p.mapper, lineno)
	if err != nil {
		return errorf("invalid position: %v", err)
	}

	return []*cache.Diagnostic{{
		Message:  msg,
		Severity: protocol.SeverityError,
		Range:    rng,
		Source:   cache.TemplateError,
	}}
}

// Definition finds the definitions of the symbol at loc. It
// does not understand scoping (if any) in templates. This code is
// for definitions, type definitions, and implementations.
// Results only for variables and templates.
func Definition(snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) ([]protocol.Location, error) {
	x, _, err := symAtRange(fh, rng)
	if err != nil {
		return nil, err
	}
	sym := x.name
	ans := []protocol.Location{}
	// PJW: this is probably a pattern to abstract
	a := parseSet(snapshot.Templates())
	for _, p := range a.files {
		for _, s := range p.symbols {
			if !s.vardef || s.name != sym {
				continue
			}
			loc, err := p.mapper.OffsetLocation(s.offsets())
			if err != nil {
				return nil, err
			}
			ans = append(ans, loc)
		}
	}
	return ans, nil
}

func Hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) (*protocol.Hover, error) {
	sym, p, err := symAtRange(fh, rng)
	if err != nil {
		return nil, err
	}

	var value string
	switch sym.kind {
	case protocol.Function:
		value = fmt.Sprintf("function: %s", sym.name)
	case protocol.Variable:
		value = fmt.Sprintf("variable: %s", sym.name)
	case protocol.Constant:
		value = fmt.Sprintf("constant %s", sym.name)
	case protocol.Method: // field or method
		value = fmt.Sprintf("%s: field or method", sym.name)
	case protocol.Package: // template use, template def (PJW: do we want two?)
		value = fmt.Sprintf("template %s\n(add definition)", sym.name)
	case protocol.Namespace:
		value = fmt.Sprintf("template %s defined", sym.name)
	case protocol.Number:
		value = "number"
	case protocol.String:
		value = "string"
	case protocol.Boolean:
		value = "boolean"
	default:
		value = fmt.Sprintf("oops, sym=%#v", sym)
	}

	symRng, err := p.mapper.OffsetRange(sym.offsets())
	if err != nil {
		return nil, err
	}

	return &protocol.Hover{
		Range: symRng,
		Contents: protocol.MarkupContent{
			Kind:  protocol.Markdown,
			Value: value,
		},
	}, nil
}

func References(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, params *protocol.ReferenceParams) ([]protocol.Location, error) {
	sym, _, err := symAtRange(fh, params.Range)
	if err != nil {
		return nil, err
	}
	if sym.name == "" {
		return nil, fmt.Errorf("no symbol at position")
	}
	ans := []protocol.Location{}

	a := parseSet(snapshot.Templates())
	for _, p := range a.files {
		for _, s := range p.symbols {
			if s.name != sym.name {
				continue
			}
			if s.vardef && !params.Context.IncludeDeclaration {
				continue
			}
			loc, err := p.mapper.OffsetLocation(s.offsets())
			if err != nil {
				return nil, err
			}
			ans = append(ans, loc)
		}
	}
	// TODO: do these need to be sorted? (a.files is a map)
	return ans, nil
}

func SemanticTokens(ctx context.Context, snapshot *cache.Snapshot, spn protocol.DocumentURI) (*protocol.SemanticTokens, error) {
	fh, err := snapshot.ReadFile(ctx, spn)
	if err != nil {
		return nil, err
	}
	buf, err := fh.Content()
	if err != nil {
		return nil, err
	}
	p := parseBuffer(fh.URI(), buf)

	var items []semtok.Token
	for _, t := range p.tokens {
		if t.start == t.end {
			continue // vscode doesn't like 0-length tokens
		}
		pos, err := p.mapper.OffsetPosition(t.start)
		if err != nil {
			return nil, err
		}
		// TODO(adonovan): don't ignore the rng restriction, if any.
		items = append(items, semtok.Token{
			Line:  pos.Line,
			Start: pos.Character,
			Len:   uint32(protocol.UTF16Len(p.buf[t.start:t.end])),
			Type:  semtok.TokMacro,
		})
	}
	return &protocol.SemanticTokens{
		Data: semtok.Encode(items, nil, nil),
		// for small cache, some day. for now, the LSP client ignores this
		// (that is, when the LSP client starts returning these, we can cache)
		ResultID: fmt.Sprintf("%v", time.Now()),
	}, nil
}

// TODO: still need to do rename, etc

func symAtRange(fh file.Handle, rng protocol.Range) (*symbol, *parsed, error) {
	buf, err := fh.Content()
	if err != nil {
		return nil, nil, err
	}
	p := parseBuffer(fh.URI(), buf)
	start, end, err := p.mapper.RangeOffsets(rng)
	if err != nil {
		return nil, nil, err
	}
	var syms []symbol
	for _, s := range p.symbols {
		if s.start <= start && end <= s.start+s.len {
			syms = append(syms, s)
		}
	}
	if len(syms) == 0 {
		return nil, p, fmt.Errorf("no symbol found")
	}
	sym := syms[0]
	return &sym, p, nil
}


================================================
FILE: gopls/internal/template/parse.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package template contains code for dealing with templates
package template

// template files are small enough that the code reprocesses them each time
// this may be a bad choice for projects with lots of template files.

import (
	"bytes"
	"fmt"
	"io"
	"log"
	"regexp"
	"sort"
	"text/template"
	"text/template/parse"

	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
)

var (
	lbraces = []byte("{{")
	rbraces = []byte("}}")
)

type parsed struct {
	buf    []byte // contents
	mapper *protocol.Mapper
	elided []int // offsets where lbraces was replaced by blanks

	// tokens are matched lbraces-rbraces pairs, computed before trying to parse
	tokens []token

	// result of parsing
	named    []*template.Template // the template and embedded templates
	parseErr error
	symbols  []symbol
	stack    []parse.Node // used while computing symbols
}

// A token is a single {{...}}.
type token struct {
	start, end int // 0-based byte offset from start of template
}

// set contains the Parse of all the template files
type set struct {
	files map[protocol.DocumentURI]*parsed
}

// parseSet returns the set of the snapshot's tmpl files
// (maybe cache these, but then avoiding import cycles needs code rearrangements)
//
// TODO(adonovan): why doesn't parseSet return an error?
func parseSet(tmpls map[protocol.DocumentURI]file.Handle) *set {
	all := make(map[protocol.DocumentURI]*parsed)
	for uri, fh := range tmpls {
		buf, err := fh.Content()
		if err != nil {
			// TODO(pjw): decide what to do with these errors
			log.Printf("failed to read %s (%v)", fh.URI().Path(), err)
			continue
		}
		all[uri] = parseBuffer(uri, buf)
	}
	return &set{files: all}
}

func parseBuffer(uri protocol.DocumentURI, buf []byte) *parsed {
	ans := &parsed{
		buf:    buf,
		mapper: protocol.NewMapper(uri, buf),
	}
	if len(buf) == 0 {
		return ans
	}
	ans.setTokens() // ans.buf may be a new []byte
	t, err := template.New("").Parse(string(ans.buf))
	if err != nil {
		funcs := make(template.FuncMap)
		for t == nil && ans.parseErr == nil {
			// in 1.17 it may be possible to avoid getting this error
			//  template: :2: function "foo" not defined
			matches := parseErrR.FindStringSubmatch(err.Error())
			if len(matches) == 2 {
				// suppress the error by giving it a function with the right name
				funcs[matches[1]] = func() any { return nil }
				t, err = template.New("").Funcs(funcs).Parse(string(ans.buf))
				continue
			}
			ans.parseErr = err // unfixed error
			return ans
		}
	}
	ans.named = t.Templates()
	// set the symbols
	for _, t := range ans.named {
		ans.stack = append(ans.stack, t.Root)
		ans.findSymbols()
		if t.Name() != "" {
			// defining a template. The pos is just after {{define...}} (or {{block...}}?)
			at, sz := ans.findLiteralBefore(int(t.Root.Pos))
			s := symbol{start: at, len: sz, name: t.Name(), kind: protocol.Namespace, vardef: true}
			ans.symbols = append(ans.symbols, s)
		}
	}

	sort.Slice(ans.symbols, func(i, j int) bool {
		left, right := ans.symbols[i], ans.symbols[j]
		if left.start != right.start {
			return left.start < right.start
		}
		if left.vardef != right.vardef {
			return left.vardef
		}
		return left.kind < right.kind
	})
	return ans
}

// findLiteralBefore locates the first preceding string literal
// returning its offset and length in buf or (-1, 0) if there is none.
// Assume double-quoted string rather than backquoted string for now.
func (p *parsed) findLiteralBefore(pos int) (int, int) {
	left, right := -1, -1
	for i := pos - 1; i >= 0; i-- {
		if p.buf[i] != '"' {
			continue
		}
		if right == -1 {
			right = i
			continue
		}
		left = i
		break
	}
	if left == -1 {
		return -1, 0
	}
	return left + 1, right - left - 1
}

var (
	parseErrR = regexp.MustCompile(`template:.*function "([^"]+)" not defined`)
)

func (p *parsed) setTokens() {
	const (
		// InRaw and InString only occur inside an action (SeenLeft)
		Start = iota
		InRaw
		InString
		SeenLeft
	)
	state := Start
	var left, oldState int
	for n := 0; n < len(p.buf); n++ {
		c := p.buf[n]
		switch state {
		case InRaw:
			if c == '`' {
				state = oldState
			}
		case InString:
			if c == '"' && !isEscaped(p.buf[:n]) {
				state = oldState
			}
		case SeenLeft:
			if c == '`' {
				oldState = state // it's SeenLeft, but a little clearer this way
				state = InRaw
				continue
			}
			if c == '"' {
				oldState = state
				state = InString
				continue
			}
			if bytes.HasPrefix(p.buf[n:], rbraces) {
				right := n + len(rbraces)
				tok := token{start: left, end: right}
				p.tokens = append(p.tokens, tok)
				state = Start
			}
			// If we see (unquoted) lbraces then the original left is probably the user
			// typing. Suppress the original left
			if bytes.HasPrefix(p.buf[n:], lbraces) {
				p.elideAt(left)
				left = n
				n += len(lbraces) - 1 // skip the rest
			}
		case Start:
			if bytes.HasPrefix(p.buf[n:], lbraces) {
				left = n
				state = SeenLeft
				n += len(lbraces) - 1 // skip the rest (avoids {{{ bug)
			}
		}
	}
	// this error occurs after typing {{ at the end of the file
	if state != Start {
		// Unclosed lbraces. remove the lbraces at left
		p.elideAt(left)
	}
}

func (p *parsed) elideAt(left int) {
	if p.elided == nil {
		// p.buf is the same buffer that v.Read() returns, so copy it.
		// (otherwise the next time it's parsed, elided information is lost)
		p.buf = bytes.Clone(p.buf)
	}
	for i := range lbraces {
		p.buf[left+i] = ' '
	}
	p.elided = append(p.elided, left)
}

// isEscaped reports whether the byte after buf is escaped
func isEscaped(buf []byte) bool {
	backSlashes := 0
	for j := len(buf) - 1; j >= 0 && buf[j] == '\\'; j-- {
		backSlashes++
	}
	return backSlashes%2 == 1
}

// lineRange returns the range for the entire specified (1-based) line.
func lineRange(m *protocol.Mapper, line int) (protocol.Range, error) {
	posn := protocol.Position{Line: uint32(line - 1)}

	// start of line
	start, err := m.PositionOffset(posn)
	if err != nil {
		return protocol.Range{}, err
	}

	// end of line (or file)
	posn.Line++
	end := len(m.Content) // EOF
	if offset, err := m.PositionOffset(posn); err != nil {
		end = offset - len("\n")
	}

	return m.OffsetRange(start, end)
}

// -- debugging --

func (p *parsed) writeNode(w io.Writer, n parse.Node) {
	wr := wrNode{p: p, w: w}
	wr.writeNode(n, "")
}

type wrNode struct {
	p *parsed
	w io.Writer
}

func (wr wrNode) writeNode(n parse.Node, indent string) {
	if n == nil {
		return
	}
	at := func(pos parse.Pos) string {
		offset := int(pos)
		posn, err := wr.p.mapper.OffsetPosition(offset)
		if err != nil {
			return fmt.Sprintf("<bad pos %d: %v>", pos, err)
		}
		return fmt.Sprintf("(%d)%v:%v", pos, posn.Line, posn.Character)
	}
	switch x := n.(type) {
	case *parse.ActionNode:
		fmt.Fprintf(wr.w, "%sActionNode at %s\n", indent, at(x.Pos))
		wr.writeNode(x.Pipe, indent+". ")
	case *parse.BoolNode:
		fmt.Fprintf(wr.w, "%sBoolNode at %s, %v\n", indent, at(x.Pos), x.True)
	case *parse.BranchNode:
		fmt.Fprintf(wr.w, "%sBranchNode at %s\n", indent, at(x.Pos))
		wr.writeNode(x.Pipe, indent+"Pipe. ")
		wr.writeNode(x.List, indent+"List. ")
		wr.writeNode(x.ElseList, indent+"Else. ")
	case *parse.ChainNode:
		fmt.Fprintf(wr.w, "%sChainNode at %s, %v\n", indent, at(x.Pos), x.Field)
	case *parse.CommandNode:
		fmt.Fprintf(wr.w, "%sCommandNode at %s, %d children\n", indent, at(x.Pos), len(x.Args))
		for _, a := range x.Args {
			wr.writeNode(a, indent+". ")
		}
	//case *parse.CommentNode: // 1.16
	case *parse.DotNode:
		fmt.Fprintf(wr.w, "%sDotNode at %s\n", indent, at(x.Pos))
	case *parse.FieldNode:
		fmt.Fprintf(wr.w, "%sFieldNode at %s, %v\n", indent, at(x.Pos), x.Ident)
	case *parse.IdentifierNode:
		fmt.Fprintf(wr.w, "%sIdentifierNode at %s, %v\n", indent, at(x.Pos), x.Ident)
	case *parse.IfNode:
		fmt.Fprintf(wr.w, "%sIfNode at %s\n", indent, at(x.Pos))
		wr.writeNode(&x.BranchNode, indent+". ")
	case *parse.ListNode:
		if x == nil {
			return // nil BranchNode.ElseList
		}
		fmt.Fprintf(wr.w, "%sListNode at %s, %d children\n", indent, at(x.Pos), len(x.Nodes))
		for _, n := range x.Nodes {
			wr.writeNode(n, indent+". ")
		}
	case *parse.NilNode:
		fmt.Fprintf(wr.w, "%sNilNode at %s\n", indent, at(x.Pos))
	case *parse.NumberNode:
		fmt.Fprintf(wr.w, "%sNumberNode at %s, %s\n", indent, at(x.Pos), x.Text)
	case *parse.PipeNode:
		if x == nil {
			return // {{template "xxx"}}
		}
		fmt.Fprintf(wr.w, "%sPipeNode at %s, %d vars, %d cmds, IsAssign:%v\n",
			indent, at(x.Pos), len(x.Decl), len(x.Cmds), x.IsAssign)
		for _, d := range x.Decl {
			wr.writeNode(d, indent+"Decl. ")
		}
		for _, c := range x.Cmds {
			wr.writeNode(c, indent+"Cmd. ")
		}
	case *parse.RangeNode:
		fmt.Fprintf(wr.w, "%sRangeNode at %s\n", indent, at(x.Pos))
		wr.writeNode(&x.BranchNode, indent+". ")
	case *parse.StringNode:
		fmt.Fprintf(wr.w, "%sStringNode at %s, %s\n", indent, at(x.Pos), x.Quoted)
	case *parse.TemplateNode:
		fmt.Fprintf(wr.w, "%sTemplateNode at %s, %s\n", indent, at(x.Pos), x.Name)
		wr.writeNode(x.Pipe, indent+". ")
	case *parse.TextNode:
		fmt.Fprintf(wr.w, "%sTextNode at %s, len %d\n", indent, at(x.Pos), len(x.Text))
	case *parse.VariableNode:
		fmt.Fprintf(wr.w, "%sVariableNode at %s, %v\n", indent, at(x.Pos), x.Ident)
	case *parse.WithNode:
		fmt.Fprintf(wr.w, "%sWithNode at %s\n", indent, at(x.Pos))
		wr.writeNode(&x.BranchNode, indent+". ")
	}
}


================================================
FILE: gopls/internal/template/parse_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import "testing"

func TestSymbols(t *testing.T) {
	for i, test := range []struct {
		buf       string
		wantNamed int      // expected number of named templates
		syms      []string // expected symbols (start, len, name, kind, def?)
	}{
		{`
{{if (foo .X.Y)}}{{$A := "hi"}}{{.Z $A}}{{else}}
{{$A.X 12}}
{{foo (.X.Y) 23 ($A.Zü)}}
{{end}}`, 1, []string{
			"{7,3,foo,Function,false}",
			"{12,1,X,Method,false}",
			"{14,1,Y,Method,false}",
			"{21,2,$A,Variable,true}",
			"{26,4,,String,false}",
			"{35,1,Z,Method,false}",
			"{38,2,$A,Variable,false}",
			"{53,2,$A,Variable,false}",
			"{56,1,X,Method,false}",
			"{57,2,,Number,false}",
			"{64,3,foo,Function,false}",
			"{70,1,X,Method,false}",
			"{72,1,Y,Method,false}",
			"{75,2,,Number,false}",
			"{80,2,$A,Variable,false}",
			"{83,3,Zü,Method,false}",
			"{94,3,,Constant,false}",
		}},
		{`{{define "zzz"}}{{.}}{{end}}
{{template "zzz"}}`, 2, []string{
			"{10,3,zzz,Namespace,true}",
			"{18,1,dot,Variable,false}",
			"{41,3,zzz,Package,false}",
		}},
		{`{{block "aaa" foo}}b{{end}}`, 2, []string{
			"{9,3,aaa,Namespace,true}",
			"{9,3,aaa,Package,false}",
			"{14,3,foo,Function,false}",
			"{19,1,,Constant,false}",
		}},
		{"", 0, nil},
		{`{{/* this is
a comment */}}`, 1, nil}, // https://go.dev/issue/74635
	} {
		got := parseBuffer("", []byte(test.buf))
		if got.parseErr != nil {
			t.Error(got.parseErr)
			continue
		}
		if len(got.named) != test.wantNamed {
			t.Errorf("%d: got %d, expected %d", i, len(got.named), test.wantNamed)
		}
		for n, s := range got.symbols {
			if s.String() != test.syms[n] {
				t.Errorf("%d: got %s, expected %s", i, s.String(), test.syms[n])
			}
		}
	}
}

func TestWordAt(t *testing.T) {
	want := []string{"", "", "$A", "$A", "", "", "", "", "", "",
		"", "", "", "if", "if", "", "$A", "$A", "", "",
		"B", "", "", "end", "end", "end", "", "", ""}
	buf := []byte("{{$A := .}}{{if $A}}B{{end}}")
	for i := range buf {
		got := wordAt(buf, i)
		if got != want[i] {
			t.Errorf("for %d, got %q, wanted %q", i, got, want[i])
		}
	}
}

func TestQuotes(t *testing.T) {
	for _, s := range []struct {
		tmpl      string
		tokCnt    int
		elidedCnt int8
	}{
		{"{{- /*comment*/ -}}", 1, 0},
		{"{{/*`\ncomment\n`*/}}", 1, 0},
		//{"{{foo\nbar}}\n", 1, 0}, // this action spanning lines parses in 1.16
		{"{{\"{{foo}}{{\"}}", 1, 0},
		{"{{\n{{- when}}", 1, 1},          // corrected
		{"{{{{if .}}xx{{\n{{end}}", 2, 2}, // corrected
	} {
		p := parseBuffer("", []byte(s.tmpl))
		if len(p.tokens) != s.tokCnt {
			t.Errorf("%#v: got %d tokens, expected %d", s, len(p.tokens), s.tokCnt)
		}
		if p.parseErr != nil {
			t.Errorf("%q: %v", string(p.buf), p.parseErr)
		}
		if len(p.elided) != int(s.elidedCnt) {
			t.Errorf("%#v: elided %d, expected %d", s, len(p.elided), s.elidedCnt)
		}
	}
}


================================================
FILE: gopls/internal/template/symbols.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"bytes"
	"context"
	"fmt"
	"text/template/parse"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

// in local coordinates, to be translated to protocol.DocumentSymbol
type symbol struct {
	start  int // 0-based byte offset, for sorting
	len    int // of source, in bytes
	name   string
	kind   protocol.SymbolKind
	vardef bool // is this a variable definition?
	// do we care about selection range, or children?
	// no children yet, and selection range is the same as range
}

func (s symbol) offsets() (start, end int) {
	return s.start, s.start + s.len
}

func (s symbol) String() string {
	return fmt.Sprintf("{%d,%d,%s,%s,%v}", s.start, s.len, s.name, s.kind, s.vardef)
}

// for FieldNode or VariableNode (or ChainNode?)
func (p *parsed) fields(flds []string, x parse.Node) []symbol {
	ans := []symbol{}
	// guessing that there are no embedded blanks allowed. The doc is unclear
	lookfor := ""
	switch x.(type) {
	case *parse.FieldNode:
		for _, f := range flds {
			lookfor += "." + f // quadratic, but probably ok
		}
	case *parse.VariableNode:
		lookfor = flds[0]
		for i := 1; i < len(flds); i++ {
			lookfor += "." + flds[i]
		}
	case *parse.ChainNode: // PJW, what are these?
		for _, f := range flds {
			lookfor += "." + f // quadratic, but probably ok
		}
	default:
		// If these happen they will happen even if gopls is restarted
		// and the users does the same thing, so it is better not to panic.
		// context.Background() is used because we don't have access
		// to any other context. [we could, but it would be complicated]
		event.Log(context.Background(), fmt.Sprintf("%T unexpected in fields()", x))
		return nil
	}
	if len(lookfor) == 0 {
		event.Log(context.Background(), fmt.Sprintf("no strings in fields() %#v", x))
		return nil
	}
	startsAt := int(x.Position())
	ix := bytes.Index(p.buf[startsAt:], []byte(lookfor)) // HasPrefix? PJW?
	if ix < 0 || ix > len(lookfor) {                     // lookfor expected to be at start (or so)
		// probably golang.go/#43388, so back up
		startsAt -= len(flds[0]) + 1
		ix = bytes.Index(p.buf[startsAt:], []byte(lookfor)) // ix might be 1? PJW
		if ix < 0 {
			return ans
		}
	}
	at := ix + startsAt
	for _, f := range flds {
		at += 1 // .
		kind := protocol.Method
		if f[0] == '$' {
			kind = protocol.Variable
		}
		sym := symbol{name: f, kind: kind, start: at, len: len(f)}
		if kind == protocol.Variable && len(p.stack) > 1 {
			if pipe, ok := p.stack[len(p.stack)-2].(*parse.PipeNode); ok {
				for _, y := range pipe.Decl {
					if x == y {
						sym.vardef = true
					}
				}
			}
		}
		ans = append(ans, sym)
		at += len(f)
	}
	return ans
}

func (p *parsed) findSymbols() {
	if len(p.stack) == 0 {
		return
	}
	n := p.stack[len(p.stack)-1]
	pop := func() {
		p.stack = p.stack[:len(p.stack)-1]
	}
	if n == nil { // allowing nil simplifies the code
		pop()
		return
	}
	nxt := func(nd parse.Node) {
		p.stack = append(p.stack, nd)
		p.findSymbols()
	}
	switch x := n.(type) {
	case *parse.ActionNode:
		nxt(x.Pipe)
	case *parse.BoolNode:
		// need to compute the length from the value
		msg := fmt.Sprintf("%v", x.True)
		p.symbols = append(p.symbols, symbol{start: int(x.Pos), len: len(msg), kind: protocol.Boolean})
	case *parse.BranchNode:
		nxt(x.Pipe)
		nxt(x.List)
		nxt(x.ElseList)
	case *parse.ChainNode:
		p.symbols = append(p.symbols, p.fields(x.Field, x)...)
		nxt(x.Node)
	case *parse.CommandNode:
		for _, a := range x.Args {
			nxt(a)
		}
	//case *parse.CommentNode: // go 1.16
	//	log.Printf("implement %d", x.Type())
	case *parse.DotNode:
		sym := symbol{name: "dot", kind: protocol.Variable, start: int(x.Pos), len: 1}
		p.symbols = append(p.symbols, sym)
	case *parse.FieldNode:
		p.symbols = append(p.symbols, p.fields(x.Ident, x)...)
	case *parse.IdentifierNode:
		sym := symbol{name: x.Ident, kind: protocol.Function, start: int(x.Pos), len: len(x.Ident)}
		p.symbols = append(p.symbols, sym)
	case *parse.IfNode:
		nxt(&x.BranchNode)
	case *parse.ListNode:
		if x != nil { // wretched typed nils. Node should have an IfNil
			for _, nd := range x.Nodes {
				nxt(nd)
			}
		}
	case *parse.NilNode:
		sym := symbol{name: "nil", kind: protocol.Constant, start: int(x.Pos), len: 3}
		p.symbols = append(p.symbols, sym)
	case *parse.NumberNode:
		// no name; ascii
		p.symbols = append(p.symbols, symbol{start: int(x.Pos), len: len(x.Text), kind: protocol.Number})
	case *parse.PipeNode:
		if x == nil { // {{template "foo"}}
			return
		}
		for _, d := range x.Decl {
			nxt(d)
		}
		for _, c := range x.Cmds {
			nxt(c)
		}
	case *parse.RangeNode:
		nxt(&x.BranchNode)
	case *parse.StringNode:
		// no name
		p.symbols = append(p.symbols, symbol{start: int(x.Pos), len: len(x.Quoted), kind: protocol.String})
	case *parse.TemplateNode:
		// invoking a template, e.g. {{define "foo"}}
		// x.Pos is the index of "foo".
		// The logic below assumes that the literal is trivial.
		p.symbols = append(p.symbols, symbol{name: x.Name, kind: protocol.Package, start: int(x.Pos) + len(`"`), len: len(x.Name)})
		nxt(x.Pipe)
	case *parse.TextNode:
		if len(x.Text) == 1 && x.Text[0] == '\n' {
			break
		}
		// nothing to report, but build one for hover
		p.symbols = append(p.symbols, symbol{start: int(x.Pos), len: len(x.Text), kind: protocol.Constant})
	case *parse.VariableNode:
		p.symbols = append(p.symbols, p.fields(x.Ident, x)...)
	case *parse.WithNode:
		nxt(&x.BranchNode)
	}
	pop()
}

// DocumentSymbols returns a hierarchy of the symbols defined in a template file.
// (The hierarchy is flat. SymbolInformation might be better.)
func DocumentSymbols(snapshot *cache.Snapshot, fh file.Handle) ([]protocol.DocumentSymbol, error) {
	buf, err := fh.Content()
	if err != nil {
		return nil, err
	}
	p := parseBuffer(fh.URI(), buf)
	if p.parseErr != nil {
		return nil, p.parseErr
	}
	var ans []protocol.DocumentSymbol
	for _, sym := range p.symbols {
		if sym.kind == protocol.Constant {
			continue
		}
		detail := kindStr(sym.kind)
		if detail == "Namespace" {
			detail = "Template"
		}
		if sym.vardef {
			detail += "(def)"
		} else {
			detail += "(use)"
		}
		rng, err := p.mapper.OffsetRange(sym.offsets())
		if err != nil {
			return nil, err
		}
		ans = append(ans, protocol.DocumentSymbol{
			Name:           sym.name,
			Detail:         detail,
			Kind:           sym.kind,
			Range:          rng,
			SelectionRange: rng, // or should this be the entire {{...}}?
		})
	}
	return ans, nil
}

func kindStr(k protocol.SymbolKind) string {
	n := int(k)
	if n < 1 || n >= len(kindNames) {
		return fmt.Sprintf("?SymbolKind %d?", n)
	}
	return kindNames[n]
}

var kindNames = []string{
	"",
	"File",
	"Module",
	"Namespace",
	"Package",
	"Class",
	"Method",
	"Property",
	"Field",
	"Constructor",
	"Enum",
	"Interface",
	"Function",
	"Variable",
	"Constant",
	"String",
	"Number",
	"Boolean",
	"Array",
	"Object",
	"Key",
	"Null",
	"EnumMember",
	"Struct",
	"Event",
	"Operator",
	"TypeParameter",
}


================================================
FILE: gopls/internal/test/compare/text.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package compare

import (
	"bytes"

	"golang.org/x/tools/internal/diff"
)

// Text returns a formatted unified diff of the edits to go from want to
// got, returning "" if and only if want == got.
//
// This function is intended for use in testing, and panics if any error occurs
// while computing the diff. It is not sufficiently tested for production use.
func Text(want, got string) string {
	return NamedText("want", "got", want, got)
}

// NamedText is like text, but allows passing custom names of the 'want' and
// 'got' content.
func NamedText(wantName, gotName, want, got string) string {
	if want == got {
		return ""
	}

	// Add newlines to avoid verbose newline messages ("No newline at end of file").
	unified := diff.Unified(wantName, gotName, want+"\n", got+"\n")

	// Defensively assert that we get an actual diff, so that we guarantee the
	// invariant that we return "" if and only if want == got.
	//
	// This is probably unnecessary, but convenient.
	if unified == "" {
		panic("empty diff for non-identical input")
	}

	return unified
}

// Bytes is like Text but using byte slices.
func Bytes(want, got []byte) string {
	if bytes.Equal(want, got) {
		return "" // common case
	}
	return Text(string(want), string(got))
}


================================================
FILE: gopls/internal/test/compare/text_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package compare_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
)

func TestText(t *testing.T) {
	tests := []struct {
		got, want, wantDiff string
	}{
		{"", "", ""},
		{"equal", "equal", ""},
		{"a", "b", "--- want\n+++ got\n@@ -1 +1 @@\n-b\n+a\n"},
		{"a\nd\nc\n", "a\nb\nc\n", "--- want\n+++ got\n@@ -1,4 +1,4 @@\n a\n-b\n+d\n c\n \n"},
	}

	for _, test := range tests {
		if gotDiff := compare.Text(test.want, test.got); gotDiff != test.wantDiff {
			t.Errorf("compare.Text(%q, %q) =\n%q, want\n%q", test.want, test.got, gotDiff, test.wantDiff)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/bench/bench_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"bytes"
	"compress/gzip"
	"context"
	"flag"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cmd"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/fakenet"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/pprof"
	"golang.org/x/tools/internal/tool"
)

var (
	goplsPath = flag.String("gopls_path", "", "if set, use this gopls for testing; incompatible with -gopls_commit")

	installGoplsOnce sync.Once // guards installing gopls at -gopls_commit
	goplsCommit      = flag.String("gopls_commit", "", "if set, install and use gopls at this commit for testing; incompatible with -gopls_path")

	cpuProfile   = flag.String("gopls_cpuprofile", "", "if set, the cpu profile file suffix; see \"Profiling\" in the package doc")
	memProfile   = flag.String("gopls_memprofile", "", "if set, the mem profile file suffix; see \"Profiling\" in the package doc")
	allocProfile = flag.String("gopls_allocprofile", "", "if set, the alloc profile file suffix; see \"Profiling\" in the package doc")
	blockProfile = flag.String("gopls_blockprofile", "", "if set, the block profile file suffix; see \"Profiling\" in the package doc")
	trace        = flag.String("gopls_trace", "", "if set, the trace file suffix; see \"Profiling\" in the package doc")

	// If non-empty, tempDir is a temporary working dir that was created by this
	// test suite.
	makeTempDirOnce sync.Once // guards creation of the temp dir
	tempDir         string
)

// if runAsGopls is "true", run the gopls command instead of the testing.M.
const runAsGopls = "_GOPLS_BENCH_RUN_AS_GOPLS"

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	if os.Getenv(runAsGopls) == "true" {
		tool.Main(context.Background(), cmd.New(), os.Args[1:])
		os.Exit(0)
	}
	event.SetExporter(nil) // don't log to stderr
	code := m.Run()
	if err := cleanup(); err != nil {
		fmt.Fprintf(os.Stderr, "cleaning up after benchmarks: %v\n", err)
		if code == 0 {
			code = 1
		}
	}
	os.Exit(code)
}

// getTempDir returns the temporary directory to use for benchmark files,
// creating it if necessary.
func getTempDir() string {
	makeTempDirOnce.Do(func() {
		var err error
		tempDir, err = os.MkdirTemp("", "gopls-bench")
		if err != nil {
			log.Fatal(err)
		}
	})
	return tempDir
}

// shallowClone performs a shallow clone of repo into dir at the given
// 'commitish' ref (any commit reference understood by git).
//
// The directory dir must not already exist.
func shallowClone(dir, repo, commitish string) error {
	if err := os.Mkdir(dir, 0750); err != nil {
		return fmt.Errorf("creating dir for %s: %v", repo, err)
	}

	// Set a timeout for git fetch. If this proves flaky, it can be removed.
	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
	defer cancel()

	// Use a shallow fetch to download just the relevant commit.
	shInit := fmt.Sprintf("git init && git fetch --depth=1 %q %q && git checkout FETCH_HEAD", repo, commitish)
	initCmd := exec.CommandContext(ctx, "/bin/sh", "-c", shInit)
	initCmd.Dir = dir
	if output, err := initCmd.CombinedOutput(); err != nil {
		return fmt.Errorf("checking out %s: %v\n%s", repo, err, output)
	}
	return nil
}

// connectEditor connects a fake editor session in the given dir, using the
// given editor config.
func connectEditor(dir string, config fake.EditorConfig, ts servertest.Connector) (*fake.Sandbox, *fake.Editor, *integration.Awaiter, error) {
	s, err := fake.NewSandbox(&fake.SandboxConfig{
		Workdir: dir,
		GOPROXY: "https://proxy.golang.org",
	})
	if err != nil {
		return nil, nil, nil, err
	}

	a := integration.NewAwaiter(s.Workdir)
	editor, err := fake.NewEditor(s, config).Connect(context.Background(), ts, a.Hooks())
	if err != nil {
		return nil, nil, nil, err
	}

	return s, editor, a, nil
}

// newGoplsConnector returns a connector that connects to a new gopls process,
// executed with the provided arguments.
func newGoplsConnector(args []string) (servertest.Connector, error) {
	if *goplsPath != "" && *goplsCommit != "" {
		panic("can't set both -gopls_path and -gopls_commit")
	}
	var (
		goplsPath = *goplsPath
		env       []string
	)
	if *goplsCommit != "" {
		goplsPath = getInstalledGopls()
	}
	if goplsPath == "" {
		var err error
		goplsPath, err = os.Executable()
		if err != nil {
			return nil, err
		}
		env = []string{fmt.Sprintf("%s=true", runAsGopls)}
	}
	return &SidecarServer{
		goplsPath: goplsPath,
		env:       env,
		args:      args,
	}, nil
}

// profileArgs returns additional command-line arguments to use when invoking
// gopls, to enable the user-requested profiles.
//
// If wantCPU is set, CPU profiling is enabled as well. Some tests may want to
// instrument profiling around specific critical sections of the benchmark,
// rather than the entire process.
//
// TODO(rfindley): like CPU, all of these would be better served by a custom
// command. Very rarely do we care about memory usage as the process exits: we
// care about specific points in time during the benchmark. mem and alloc
// should be snapshotted, and tracing should be bracketed around critical
// sections.
func profileArgs(name string, wantCPU bool) []string {
	var args []string
	if wantCPU && *cpuProfile != "" {
		args = append(args, fmt.Sprintf("-profile.cpu=%s", qualifiedName(name, *cpuProfile)))
	}
	if *memProfile != "" {
		args = append(args, fmt.Sprintf("-profile.mem=%s", qualifiedName(name, *memProfile)))
	}
	if *allocProfile != "" {
		args = append(args, fmt.Sprintf("-profile.alloc=%s", qualifiedName(name, *allocProfile)))
	}
	if *blockProfile != "" {
		args = append(args, fmt.Sprintf("-profile.block=%s", qualifiedName(name, *blockProfile)))
	}
	if *trace != "" {
		args = append(args, fmt.Sprintf("-profile.trace=%s", qualifiedName(name, *trace)))
	}
	return args
}

func qualifiedName(args ...string) string {
	return strings.Join(args, ".")
}

// getInstalledGopls builds gopls at the given -gopls_commit, returning the
// path to the gopls binary.
func getInstalledGopls() string {
	if *goplsCommit == "" {
		panic("must provide -gopls_commit")
	}
	toolsDir := filepath.Join(getTempDir(), "gopls_build")
	goplsPath := filepath.Join(toolsDir, "gopls", "gopls")

	installGoplsOnce.Do(func() {
		log.Printf("installing gopls: checking out x/tools@%s into %s\n", *goplsCommit, toolsDir)
		if err := shallowClone(toolsDir, "https://go.googlesource.com/tools", *goplsCommit); err != nil {
			log.Fatal(err)
		}

		log.Println("installing gopls: building...")
		bld := exec.Command("go", "build", ".")
		bld.Dir = filepath.Join(toolsDir, "gopls")
		if output, err := bld.CombinedOutput(); err != nil {
			log.Fatalf("building gopls: %v\n%s", err, output)
		}

		// Confirm that the resulting path now exists.
		if _, err := os.Stat(goplsPath); err != nil {
			log.Fatalf("os.Stat(%s): %v", goplsPath, err)
		}
	})
	return goplsPath
}

// A SidecarServer starts (and connects to) a separate gopls process at the
// given path.
type SidecarServer struct {
	goplsPath string
	env       []string // additional environment bindings
	args      []string // command-line arguments
}

// Connect creates new io.Pipes and binds them to the underlying StreamServer.
//
// It implements the servertest.Connector interface.
func (s *SidecarServer) Connect(ctx context.Context) jsonrpc2.Conn {
	// Note: don't use CommandContext here, as we want gopls to exit gracefully
	// in order to write out profile data.
	//
	// We close the connection on context cancellation below.
	cmd := exec.Command(s.goplsPath, s.args...)

	stdin, err := cmd.StdinPipe()
	if err != nil {
		log.Fatal(err)
	}
	stdout, err := cmd.StdoutPipe()
	if err != nil {
		log.Fatal(err)
	}
	cmd.Stderr = os.Stderr
	cmd.Env = append(os.Environ(), s.env...)
	if err := cmd.Start(); err != nil {
		log.Fatalf("starting gopls: %v", err)
	}

	go func() {
		// If we don't log.Fatal here, benchmarks may hang indefinitely if gopls
		// exits abnormally.
		//
		// TODO(rfindley): ideally we would shut down the connection gracefully,
		// but that doesn't currently work.
		if err := cmd.Wait(); err != nil {
			log.Fatalf("gopls invocation failed with error: %v", err)
		}
	}()

	clientStream := jsonrpc2.NewHeaderStream(fakenet.NewConn("stdio", stdout, stdin))
	clientConn := jsonrpc2.NewConn(clientStream)

	go func() {
		select {
		case <-ctx.Done():
			clientConn.Close()   // ignore error
			clientStream.Close() // ignore error
		case <-clientConn.Done():
		}
	}()

	return clientConn
}

// startProfileIfSupported checks to see if the remote gopls instance supports
// the start/stop profiling commands. If so, it starts profiling and returns a
// function that stops profiling and records the total CPU seconds sampled in the
// cpu_seconds benchmark metric.
//
// If the remote gopls instance does not support profiling commands, this
// function returns nil.
//
// If the supplied userSuffix is non-empty, the profile is written to
// <repo>.<userSuffix>, and not deleted when the benchmark exits. Otherwise,
// the profile is written to a temp file that is deleted after the cpu_seconds
// metric has been computed.
func startProfileIfSupported(b *testing.B, env *integration.Env, name string) func() {
	if !env.Editor.HasCommand(command.StartProfile) {
		return nil
	}
	b.StopTimer()
	stopProfile := env.StartProfile()
	b.StartTimer()
	return func() {
		b.StopTimer()
		profFile := stopProfile()
		totalCPU, err := totalCPUForProfile(profFile)
		if err != nil {
			b.Fatalf("reading profile: %v", err)
		}
		b.ReportMetric(totalCPU.Seconds()/float64(b.N), "cpu_seconds/op")
		if *cpuProfile != "" {
			// Read+write to avoid exdev errors.
			data, err := os.ReadFile(profFile)
			if err != nil {
				b.Fatalf("reading profile: %v", err)
			}
			name := qualifiedName(name, *cpuProfile)
			if err := os.WriteFile(name, data, 0666); err != nil {
				b.Fatalf("writing profile: %v", err)
			}
		}
		if err := os.Remove(profFile); err != nil {
			b.Errorf("removing profile file: %v", err)
		}
	}
}

// totalCPUForProfile reads the pprof profile with the given file name, parses,
// and aggregates the total CPU sampled during the profile.
func totalCPUForProfile(filename string) (time.Duration, error) {
	protoGz, err := os.ReadFile(filename)
	if err != nil {
		return 0, err
	}
	rd, err := gzip.NewReader(bytes.NewReader(protoGz))
	if err != nil {
		return 0, fmt.Errorf("creating gzip reader for %s: %v", filename, err)
	}
	data, err := io.ReadAll(rd)
	if err != nil {
		return 0, fmt.Errorf("reading %s: %v", filename, err)
	}
	return pprof.TotalTime(data)
}

// closeBuffer stops the benchmark timer and closes the buffer with the given
// name.
//
// It may be used to clean up files opened in the shared environment during
// benchmarking.
func closeBuffer(b *testing.B, env *integration.Env, name string) {
	b.StopTimer()
	env.CloseBuffer(name)
	env.AfterChange()
	b.StartTimer()
}


================================================
FILE: gopls/internal/test/integration/bench/codeaction_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"fmt"
	"sync/atomic"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

func BenchmarkCodeAction(b *testing.B) {
	for _, test := range didChangeTests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)
			env.AfterChange()

			env.CodeActionForFile(test.file, nil) // pre-warm

			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "hover")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.CodeActionForFile(test.file, nil)
			}
		})
	}
}

func BenchmarkCodeActionFollowingEdit(b *testing.B) {
	for _, test := range didChangeTests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)
			env.EditBuffer(test.file, protocol.TextEdit{NewText: "// __TEST_PLACEHOLDER_0__\n"})
			env.AfterChange()

			env.CodeActionForFile(test.file, nil) // pre-warm

			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "hover")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				edits := atomic.AddInt64(&editID, 1)
				env.EditBuffer(test.file, protocol.TextEdit{
					Range: protocol.Range{
						Start: protocol.Position{Line: 0, Character: 0},
						End:   protocol.Position{Line: 1, Character: 0},
					},
					// Increment the placeholder text, to ensure cache misses.
					NewText: fmt.Sprintf("// __TEST_PLACEHOLDER_%d__\n", edits),
				})
				env.CodeActionForFile(test.file, nil)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/completion_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"flag"
	"fmt"
	"sync/atomic"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

var completionGOPATH = flag.String("completion_gopath", "", "if set, use this GOPATH for BenchmarkCompletion")

type completionBenchOptions struct {
	file, locationRegexp string

	// Hooks to run edits before initial completion
	setup            func(*Env) // run before the benchmark starts
	beforeCompletion func(*Env) // run before each completion
}

// Deprecated: new tests should be expressed in BenchmarkCompletion.
func benchmarkCompletion(options completionBenchOptions, b *testing.B) {
	repo := getRepo(b, "tools")
	_ = repo.sharedEnv(b) // ensure cache is warm
	env := repo.newEnv(b, fake.EditorConfig{}, "completion", false)
	defer env.Close()

	// Run edits required for this completion.
	if options.setup != nil {
		options.setup(env)
	}

	// Run a completion to make sure the system is warm.
	loc := env.RegexpSearch(options.file, options.locationRegexp)
	completions := env.Completion(loc)

	if testing.Verbose() {
		fmt.Println("Results:")
		for i := 0; i < len(completions.Items); i++ {
			fmt.Printf("\t%d. %v\n", i, completions.Items[i])
		}
	}

	b.Run("tools", func(b *testing.B) {
		if stopAndRecord := startProfileIfSupported(b, env, qualifiedName("tools", "completion")); stopAndRecord != nil {
			defer stopAndRecord()
		}

		for b.Loop() {
			if options.beforeCompletion != nil {
				options.beforeCompletion(env)
			}
			env.Completion(loc)
		}
	})
}

// endRangeInBuffer returns the position for last character in the buffer for
// the given file.
func endRangeInBuffer(env *Env, name string) protocol.Range {
	buffer := env.BufferText(name)
	m := protocol.NewMapper("", []byte(buffer))
	rng, err := m.OffsetRange(len(buffer), len(buffer))
	if err != nil {
		env.TB.Fatal(err)
	}
	return rng
}

// Benchmark struct completion in tools codebase.
func BenchmarkStructCompletion(b *testing.B) {
	file := "internal/lsp/cache/session.go"

	setup := func(env *Env) {
		env.OpenFile(file)
		env.EditBuffer(file, protocol.TextEdit{
			Range:   endRangeInBuffer(env, file),
			NewText: "\nvar testVariable map[string]bool = Session{}.\n",
		})
	}

	benchmarkCompletion(completionBenchOptions{
		file:           file,
		locationRegexp: `var testVariable map\[string\]bool = Session{}(\.)`,
		setup:          setup,
	}, b)
}

// Benchmark import completion in tools codebase.
func BenchmarkImportCompletion(b *testing.B) {
	const file = "internal/lsp/source/completion/completion.go"
	benchmarkCompletion(completionBenchOptions{
		file:           file,
		locationRegexp: `go\/()`,
		setup:          func(env *Env) { env.OpenFile(file) },
	}, b)
}

// Benchmark slice completion in tools codebase.
func BenchmarkSliceCompletion(b *testing.B) {
	file := "internal/lsp/cache/session.go"

	setup := func(env *Env) {
		env.OpenFile(file)
		env.EditBuffer(file, protocol.TextEdit{
			Range:   endRangeInBuffer(env, file),
			NewText: "\nvar testVariable []byte = \n",
		})
	}

	benchmarkCompletion(completionBenchOptions{
		file:           file,
		locationRegexp: `var testVariable \[\]byte (=)`,
		setup:          setup,
	}, b)
}

// Benchmark deep completion in function call in tools codebase.
func BenchmarkFuncDeepCompletion(b *testing.B) {
	file := "internal/lsp/source/completion/completion.go"
	fileContent := `
func (c *completer) _() {
	c.inference.kindMatches(c.)
}
`
	setup := func(env *Env) {
		env.OpenFile(file)
		originalBuffer := env.BufferText(file)
		env.EditBuffer(file, protocol.TextEdit{
			Range: endRangeInBuffer(env, file),
			// TODO(rfindley): this is a bug: it should just be fileContent.
			NewText: originalBuffer + fileContent,
		})
	}

	benchmarkCompletion(completionBenchOptions{
		file:           file,
		locationRegexp: `func \(c \*completer\) _\(\) {\n\tc\.inference\.kindMatches\((c)`,
		setup:          setup,
	}, b)
}

type completionTest struct {
	repo           string
	name           string
	file           string // repo-relative file to create
	content        string // file content
	locationRegexp string // regexp for completion
}

var completionTests = []completionTest{
	{
		"tools",
		"selector",
		"internal/lsp/source/completion/completion2.go",
		`
package completion

func (c *completer) _() {
	c.inference.kindMatches(c.)
}
`,
		`func \(c \*completer\) _\(\) {\n\tc\.inference\.kindMatches\((c)`,
	},
	{
		"tools",
		"unimportedident",
		"internal/lsp/source/completion/completion2.go",
		`
package completion

func (c *completer) _() {
	lo
}
`,
		`lo()`,
	},
	{
		"tools",
		"unimportedselector",
		"internal/lsp/source/completion/completion2.go",
		`
package completion

func (c *completer) _() {
	log.
}
`,
		`log\.()`,
	},
	{
		"kubernetes",
		"selector",
		"pkg/kubelet/kubelet2.go",
		`
package kubelet

func (kl *Kubelet) _() {
	kl.
}
`,
		`kl\.()`,
	},
	{
		"kubernetes",
		"identifier",
		"pkg/kubelet/kubelet2.go",
		`
package kubelet

func (kl *Kubelet) _() {
	k // here
}
`,
		`k() // here`,
	},
	{
		"oracle",
		"selector",
		"dataintegration/pivot2.go",
		`
package dataintegration

func (p *Pivot) _() {
	p.
}
`,
		`p\.()`,
	},
}

// Benchmark completion following an arbitrary edit.
//
// Edits force type-checked packages to be invalidated, so we want to measure
// how long it takes before completion results are available.
func BenchmarkCompletion(b *testing.B) {
	for _, test := range completionTests {
		b.Run(fmt.Sprintf("%s_%s", test.repo, test.name), func(b *testing.B) {
			for _, followingEdit := range []bool{true, false} {
				b.Run(fmt.Sprintf("edit=%v", followingEdit), func(b *testing.B) {
					for _, completeUnimported := range []bool{true, false} {
						b.Run(fmt.Sprintf("unimported=%v", completeUnimported), func(b *testing.B) {
							for _, budget := range []string{"0s", "100ms"} {
								b.Run(fmt.Sprintf("budget=%s", budget), func(b *testing.B) {
									runCompletion(b, test, followingEdit, completeUnimported, budget)
								})
							}
						})
					}
				})
			}
		})
	}
}

// For optimizing unimported completion, it can be useful to benchmark with a
// huge GOMODCACHE.
var gomodcache = flag.String("gomodcache", "", "optional GOMODCACHE for unimported completion benchmarks")

func runCompletion(b *testing.B, test completionTest, followingEdit, completeUnimported bool, budget string) {
	repo := getRepo(b, test.repo)
	gopath := *completionGOPATH
	if gopath == "" {
		// use a warm GOPATH
		sharedEnv := repo.sharedEnv(b)
		gopath = sharedEnv.Sandbox.GOPATH()
	}
	envvars := map[string]string{
		"GOPATH": gopath,
	}

	if *gomodcache != "" {
		envvars["GOMODCACHE"] = *gomodcache
	}

	env := repo.newEnv(b, fake.EditorConfig{
		Env: envvars,
		Settings: map[string]any{
			"completeUnimported": completeUnimported,
			"completionBudget":   budget,
		},
	}, "completion", false)
	defer env.Close()

	env.CreateBuffer(test.file, "// __TEST_PLACEHOLDER_0__\n"+test.content)
	editPlaceholder := func() {
		edits := atomic.AddInt64(&editID, 1)
		env.EditBuffer(test.file, protocol.TextEdit{
			Range: protocol.Range{
				Start: protocol.Position{Line: 0, Character: 0},
				End:   protocol.Position{Line: 1, Character: 0},
			},
			// Increment the placeholder text, to ensure cache misses.
			NewText: fmt.Sprintf("// __TEST_PLACEHOLDER_%d__\n", edits),
		})
	}
	env.AfterChange()

	// Run a completion to make sure the system is warm.
	loc := env.RegexpSearch(test.file, test.locationRegexp)
	completions := env.Completion(loc)

	if testing.Verbose() {
		fmt.Println("Results:")
		for i, item := range completions.Items {
			fmt.Printf("\t%d. %v\n", i, item)
		}
	}

	if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "completion")); stopAndRecord != nil {
		defer stopAndRecord()
	}

	for b.Loop() {
		if followingEdit {
			editPlaceholder()
		}
		loc := env.RegexpSearch(test.file, test.locationRegexp)
		env.Completion(loc)
	}
}


================================================
FILE: gopls/internal/test/integration/bench/definition_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"testing"
)

func BenchmarkDefinition(b *testing.B) {
	tests := []struct {
		repo   string
		file   string
		regexp string
	}{
		{"istio", "pkg/config/model.go", `gogotypes\.(MarshalAny)`},
		{"google-cloud-go", "httpreplay/httpreplay.go", `proxy\.(ForRecording)`},
		{"kubernetes", "pkg/controller/lookup_cache.go", `hashutil\.(DeepHashObject)`},
		{"kuma", "api/generic/insights.go", `proto\.(Message)`},
		{"pkgsite", "internal/log/log.go", `derrors\.(Wrap)`},
		{"starlark", "starlark/eval.go", "prog.compiled.(Encode)"},
		{"tools", "internal/lsp/cache/check.go", `(snapshot)\) buildKey`},
	}

	for _, test := range tests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			loc := env.RegexpSearch(test.file, test.regexp)
			env.Await(env.DoneWithOpen())
			env.FirstDefinition(loc) // pre-warm the query, and open the target file
			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "definition")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.FirstDefinition(loc) // pre-warm the query
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/diagnostic_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"sync"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

// BenchmarkDiagnosePackageFiles measures how long it takes to request
// diagnostics for 10 files in a single package, following a change to that
// package.
//
// This can be used to measure the efficiency of pull diagnostics
// (golang/go#53275).
func BenchmarkDiagnosePackageFiles(b *testing.B) {
	if testing.Short() {
		b.Skip("pull diagnostics are not supported by the benchmark dashboard baseline")
	}

	env := getRepo(b, "kubernetes").newEnv(b, fake.EditorConfig{
		Settings: map[string]any{
			"pullDiagnostics": true, // currently required for pull diagnostic support
		},
	}, "diagnosePackageFiles", false)

	// 10 arbitrary files in a single package.
	files := []string{
		"pkg/kubelet/active_deadline.go",      // 98 lines
		"pkg/kubelet/active_deadline_test.go", // 95 lines
		"pkg/kubelet/kubelet.go",              // 2439 lines
		"pkg/kubelet/kubelet_pods.go",         // 2061 lines
		"pkg/kubelet/kubelet_network.go",      // 70 lines
		"pkg/kubelet/kubelet_network_test.go", // 46 lines
		"pkg/kubelet/pod_workers.go",          // 1323 lines
		"pkg/kubelet/pod_workers_test.go",     // 1758 lines
		"pkg/kubelet/runonce.go",              // 175 lines
		"pkg/kubelet/volume_host.go",          // 297 lines
	}

	env.Await(InitialWorkspaceLoad)

	for _, file := range files {
		env.OpenFile(file)
	}

	env.AfterChange()

	edit := makeEditFunc(env, files[0])

	if stopAndRecord := startProfileIfSupported(b, env, qualifiedName("kubernetes", "diagnosePackageFiles")); stopAndRecord != nil {
		defer stopAndRecord()
	}

	for b.Loop() {
		edit()
		var wg sync.WaitGroup
		for _, file := range files {
			wg.Go(func() {
				fileDiags := env.Diagnostics(file)
				for _, d := range fileDiags {
					if d.Severity == protocol.SeverityError {
						b.Errorf("unexpected error diagnostic: %s", d.Message)
					}
				}
			})
		}
		wg.Wait()
	}
}


================================================
FILE: gopls/internal/test/integration/bench/didchange_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"fmt"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

// Use a global edit counter as bench function may execute multiple times, and
// we want to avoid cache hits. Use time.Now to also avoid cache hits from the
// shared file cache.
var editID int64 = time.Now().UnixNano()

type changeTest struct {
	repo    string // repo identifier + optional disambiguating ".foo" suffix
	file    string
	canSave bool
}

var didChangeTests = []changeTest{
	{"google-cloud-go", "internal/annotate.go", true},
	{"istio", "pkg/fuzz/util.go", true},
	{"kubernetes", "pkg/controller/lookup_cache.go", true},
	// disable kubernetes.types as it fails on the builders, but not locally on mac or glinux
	// error is didchange_test.go:134: formatting before save: editing "..."": column is beyond end of line;
	{"kubernetes.types", "staging/src/k8s.io/api/core/v1/types.go", false}, // results in 25K file batch!
	{"kuma", "api/generic/insights.go", true},
	{"oracle", "dataintegration/data_type.go", false}, // diagnoseSave fails because this package is generated
	{"pkgsite", "internal/frontend/server.go", true},
	{"starlark", "starlark/eval.go", true},
	{"tools", "internal/lsp/cache/snapshot.go", true},
}

// BenchmarkDidChange benchmarks modifications of a single file by making
// synthetic modifications in a comment. It controls pacing by waiting for the
// server to actually start processing the didChange notification before
// proceeding. Notably it does not wait for diagnostics to complete.
func BenchmarkDidChange(b *testing.B) {
	for _, test := range didChangeTests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			// Insert the text we'll be modifying at the top of the file.
			edit := makeEditFunc(env, test.file)

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "didchange")); stopAndRecord != nil {
				defer stopAndRecord()
			}
			b.ResetTimer()

			for b.Loop() {
				edit()
				env.Await(env.StartedChange())
			}
		})
	}
}

// makeEditFunc prepares the given file for incremental editing, by inserting a
// placeholder comment that will be overwritten with a new unique value by each
// call to the resulting function. While makeEditFunc awaits gopls to finish
// processing the initial edit, the callback for incremental edits does not
// await any gopls state.
//
// This is used for benchmarks that must repeatedly invalidate a file's
// contents.
//
// TODO(rfindley): use this throughout.
func makeEditFunc(env *Env, file string) func() {
	// Insert the text we'll be modifying at the top of the file.
	env.EditBuffer(file, protocol.TextEdit{NewText: "// __TEST_PLACEHOLDER_0__\n"})
	env.AfterChange()

	return func() {
		edits := atomic.AddInt64(&editID, 1)
		env.EditBuffer(file, protocol.TextEdit{
			Range: protocol.Range{
				Start: protocol.Position{Line: 0, Character: 0},
				End:   protocol.Position{Line: 1, Character: 0},
			},
			// Increment the placeholder text, to ensure cache misses.
			NewText: fmt.Sprintf("// __TEST_PLACEHOLDER_%d__\n", edits),
		})
	}
}

func BenchmarkDiagnoseChange(b *testing.B) {
	for _, test := range didChangeTests {
		runChangeDiagnosticsBenchmark(b, test, false, "diagnoseChange")
	}
}

// TODO(rfindley): add a benchmark for with a metadata-affecting change, when
// this matters.
func BenchmarkDiagnoseSave(b *testing.B) {
	for _, test := range didChangeTests {
		runChangeDiagnosticsBenchmark(b, test, true, "diagnoseSave")
	}
}

// runChangeDiagnosticsBenchmark runs a benchmark to edit the test file and
// await the resulting diagnostics pass. If save is set, the file is also saved.
func runChangeDiagnosticsBenchmark(b *testing.B, test changeTest, save bool, operation string) {
	b.Run(test.repo, func(b *testing.B) {
		if !test.canSave {
			b.Skipf("skipping as %s cannot be saved", test.file)
		}
		sharedEnv := getRepo(b, test.repo).sharedEnv(b)
		config := fake.EditorConfig{
			Env: map[string]string{
				"GOPATH": sharedEnv.Sandbox.GOPATH(),
			},
			Settings: map[string]any{
				"diagnosticsDelay": "0s",
			},
		}
		// Use a new env to avoid the diagnostic delay: we want to measure how
		// long it takes to produce the diagnostics.
		env := getRepo(b, test.repo).newEnv(b, config, operation, false)
		defer env.Close()
		env.OpenFile(test.file)
		// Insert the text we'll be modifying at the top of the file.
		env.EditBuffer(test.file, protocol.TextEdit{NewText: "// __TEST_PLACEHOLDER_0__\n"})
		if save {
			env.SaveBuffer(test.file)
		}
		env.AfterChange()
		b.ResetTimer()

		// We must use an extra subtest layer here, so that we only set up the
		// shared env once (otherwise we pay additional overhead and the profiling
		// flags don't work).
		b.Run("diagnose", func(b *testing.B) {
			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, operation)); stopAndRecord != nil {
				defer stopAndRecord()
			}
			for b.Loop() {
				edits := atomic.AddInt64(&editID, 1)
				env.EditBuffer(test.file, protocol.TextEdit{
					Range: protocol.Range{
						Start: protocol.Position{Line: 0, Character: 0},
						End:   protocol.Position{Line: 1, Character: 0},
					},
					// Increment the placeholder text, to ensure cache misses.
					NewText: fmt.Sprintf("// __TEST_PLACEHOLDER_%d__\n", edits),
				})
				if save {
					env.SaveBuffer(test.file)
				}
				env.AfterChange()
			}
		})
	})
}


================================================
FILE: gopls/internal/test/integration/bench/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The bench package implements benchmarks for various LSP operations.
//
// Benchmarks check out specific commits of popular and/or exemplary
// repositories, and script an external gopls process via a fake text editor.
// By default, benchmarks run the test executable as gopls (using a special
// "gopls mode" environment variable). A different gopls binary may be used by
// setting the -gopls_path or -gopls_commit flags.
//
// This package is a work in progress.
//
// # Profiling
//
// Benchmark functions run gopls in a separate process, which means the normal
// test flags for profiling aren't useful. Instead the -gopls_cpuprofile,
// -gopls_memprofile, -gopls_allocprofile, -gopls_blockprofile, and
// -gopls_trace flags may be used to pass through profiling to the gopls
// subprocess.
//
// Each of these flags sets a suffix for the respective gopls profile, which is
// named according to the schema <repo>.<operation>.<suffix>. For example,
// setting -gopls_cpuprofile=cpu will result in profiles named tools.iwl.cpu,
// tools.rename.cpu, etc. In some cases, these profiles are for the entire
// gopls subprocess (as in the initial workspace load), whereas in others they
// span only the critical section of the benchmark. It is up to each benchmark
// to implement profiling as appropriate.
//
// # Integration with perf.golang.org
//
// Benchmarks that run with -short are automatically tracked by
// perf.golang.org, at
// https://perf.golang.org/dashboard/?benchmark=all&repository=tools&branch=release-branch.go1.20
//
// # TODO
//   - add more benchmarks, and more repositories
//   - fix the perf dashboard to not require the branch= parameter
//   - improve this documentation
package bench


================================================
FILE: gopls/internal/test/integration/bench/hover_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"testing"
)

func BenchmarkHover(b *testing.B) {
	tests := []struct {
		repo   string
		file   string
		regexp string
	}{
		{"google-cloud-go", "httpreplay/httpreplay.go", `proxy\.(ForRecording)`},
		{"istio", "pkg/config/model.go", `gogotypes\.(MarshalAny)`},
		{"kubernetes", "pkg/apis/core/types.go", "type (Pod)"},
		{"kuma", "api/generic/insights.go", `proto\.(Message)`},
		{"pkgsite", "internal/log/log.go", `derrors\.(Wrap)`},
		{"starlark", "starlark/eval.go", "prog.compiled.(Encode)"},
		{"tools", "internal/lsp/cache/check.go", `(snapshot)\) buildKey`},
	}

	for _, test := range tests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			loc := env.RegexpSearch(test.file, test.regexp)
			env.AfterChange()

			env.Hover(loc) // pre-warm the query
			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "hover")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.Hover(loc) // pre-warm the query
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/implementations_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import "testing"

func BenchmarkImplementations(b *testing.B) {
	tests := []struct {
		repo   string
		file   string
		regexp string
	}{
		{"google-cloud-go", "httpreplay/httpreplay.go", `type (Recorder)`},
		{"istio", "pkg/config/mesh/watcher.go", `type (Watcher)`},
		{"kubernetes", "pkg/controller/lookup_cache.go", `objectWithMeta`},
		{"kuma", "api/generic/insights.go", `type (Insight)`},
		{"pkgsite", "internal/datasource.go", `type (DataSource)`},
		{"starlark", "syntax/syntax.go", `type (Expr)`},
		{"tools", "internal/lsp/source/view.go", `type (Snapshot)`},
	}

	for _, test := range tests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			loc := env.RegexpSearch(test.file, test.regexp)
			env.AfterChange()
			env.Implementations(loc) // pre-warm the query
			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "implementations")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.Implementations(loc)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/imports_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"context"
	"flag"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

var gopath = flag.String("gopath", "", "if set, run goimports scan with this GOPATH value")

func BenchmarkInitialGoimportsScan(b *testing.B) {
	if *gopath == "" {
		// This test doesn't make much sense with a tiny module cache.
		// For now, don't bother trying to construct a huge cache, since it likely
		// wouldn't work well on the perf builder. Instead, this benchmark only
		// runs with a pre-existing GOPATH.
		b.Skip("imports scan requires an explicit GOPATH to be set with -gopath")
	}

	repo := getRepo(b, "tools") // since this a test of module cache scanning, any repo will do

	for b.Loop() {
		func() {
			// Unfortunately we (intentionally) don't support resetting the module
			// cache scan state, so in order to have an accurate benchmark we must
			// effectively restart gopls on every iteration.
			//
			// Warning: this can cause this benchmark to run quite slowly if the
			// observed time (when the timer is running) is a tiny fraction of the
			// actual time.
			b.StopTimer()
			config := fake.EditorConfig{
				Env: map[string]string{"GOPATH": *gopath},
			}
			env := repo.newEnv(b, config, "imports", false)
			defer env.Close()
			env.Await(InitialWorkspaceLoad)

			// Create a buffer with a dangling selector where the receiver is a single
			// character ('a') that matches a large fraction of the module cache.
			env.CreateBuffer("internal/lsp/cache/temp.go", `
// This is a temp file to exercise goimports scan of the module cache.
package cache

func _() {
	_ = a.B // a dangling selector causes goimports to scan many packages
}
`)
			env.AfterChange()

			// Force a scan of the imports cache, so that the goimports algorithm
			// observes all directories.
			env.ExecuteCommand(&protocol.ExecuteCommandParams{
				Command: command.ScanImports.String(),
			}, nil)

			if stopAndRecord := startProfileIfSupported(b, env, "importsscan"); stopAndRecord != nil {
				defer stopAndRecord()
			}

			b.StartTimer()
			if false {
				// golang/go#67923: testing resuming imports scanning after a
				// cancellation.
				//
				// Cancelling and then resuming the scan should take around the same
				// amount of time.
				ctx, cancel := context.WithTimeout(env.Ctx, 50*time.Millisecond)
				defer cancel()
				if err := env.Editor.OrganizeImports(ctx, "internal/lsp/cache/temp.go"); err != nil {
					b.Logf("organize imports failed: %v", err)
				}
			}
			env.OrganizeImports("internal/lsp/cache/temp.go")
		}()
	}
}


================================================
FILE: gopls/internal/test/integration/bench/iwl_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

// BenchmarkInitialWorkspaceLoad benchmarks the initial workspace load time for
// a new editing session.
//
// The OpenFiles variant of this test is more realistic: who cares if gopls is
// initialized if you can't use it? However, this test is left as is to
// preserve the validity of historical data, and to represent the baseline
// performance of validating the workspace state.
func BenchmarkInitialWorkspaceLoad(b *testing.B) {
	repoNames := []string{
		"google-cloud-go",
		"istio",
		"kubernetes",
		"kuma",
		"oracle",
		"pkgsite",
		"starlark",
		"tools",
		"hashiform",
	}
	for _, repoName := range repoNames {
		b.Run(repoName, func(b *testing.B) {
			repo := getRepo(b, repoName)
			// get the (initialized) shared env to ensure the cache is warm.
			// Reuse its GOPATH so that we get cache hits for things in the module
			// cache.
			sharedEnv := repo.sharedEnv(b)
			b.ResetTimer()

			for b.Loop() {
				doIWL(b, sharedEnv.Sandbox.GOPATH(), repo, nil)
			}
		})
	}
}

// BenchmarkInitialWorkspaceLoadOpenFiles benchmarks the initial workspace load
// after opening one or more files.
//
// It may differ significantly from [BenchmarkInitialWorkspaceLoad], since
// there is various active state that is proportional to the number of open
// files.
func BenchmarkInitialWorkspaceLoadOpenFiles(b *testing.B) {
	for _, t := range didChangeTests {
		b.Run(t.repo, func(b *testing.B) {
			repo := getRepo(b, t.repo)
			sharedEnv := repo.sharedEnv(b)
			b.ResetTimer()

			for b.Loop() {
				doIWL(b, sharedEnv.Sandbox.GOPATH(), repo, []string{t.file})
			}
		})
	}
}

func doIWL(b *testing.B, gopath string, repo *repo, openfiles []string) {
	// Exclude the time to set up the env from the benchmark time, as this may
	// involve installing gopls and/or checking out the repo dir.
	b.StopTimer()
	config := fake.EditorConfig{Env: map[string]string{"GOPATH": gopath}}
	env := repo.newEnv(b, config, "iwl", true)
	defer env.Close()
	b.StartTimer()

	// TODO(rfindley): not awaiting the IWL here leads to much more volatile
	// results. Investigate.
	env.Await(InitialWorkspaceLoad)

	for _, f := range openfiles {
		env.OpenFile(f)
	}

	env.AfterChange()

	if env.Editor.HasCommand(command.MemStats) {
		b.StopTimer()
		params := &protocol.ExecuteCommandParams{
			Command: command.MemStats.String(),
		}
		var memstats command.MemStatsResult
		env.ExecuteCommand(params, &memstats)
		b.ReportMetric(float64(memstats.HeapAlloc), "alloc_bytes")
		b.ReportMetric(float64(memstats.HeapInUse), "in_use_bytes")
		b.ReportMetric(float64(memstats.TotalAlloc), "total_alloc_bytes")
		b.StartTimer()
	}
}


================================================
FILE: gopls/internal/test/integration/bench/references_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import "testing"

func BenchmarkReferences(b *testing.B) {
	tests := []struct {
		repo   string
		file   string
		regexp string
	}{
		{"google-cloud-go", "httpreplay/httpreplay.go", `func (NewRecorder)`},
		{"istio", "pkg/config/model.go", "type (Meta)"},
		{"kubernetes", "pkg/controller/lookup_cache.go", "type (objectWithMeta)"}, // TODO: choose an exported identifier
		{"kuma", "pkg/events/interfaces.go", "type (Event)"},
		{"pkgsite", "internal/log/log.go", "func (Infof)"},
		{"starlark", "syntax/syntax.go", "type (Ident)"},
		{"tools", "internal/lsp/source/view.go", "type (Snapshot)"},
	}

	for _, test := range tests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			loc := env.RegexpSearch(test.file, test.regexp)
			env.AfterChange()
			env.References(loc) // pre-warm the query
			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "references")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.References(loc)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/reload_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package bench

import (
	"fmt"
	"path"
	"regexp"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// BenchmarkReload benchmarks reloading a file metadata after a change to an import.
//
// This ensures we are able to diagnose a changed file without reloading all
// invalidated packages. See also golang/go#61344
func BenchmarkReload(b *testing.B) {
	type replace map[string]string
	tests := []struct {
		repo string
		file string
		// replacements must be 'reversible', in the sense that the replacing
		// string is unique.
		replace replace
	}{
		// pkg/util/hash is transitively imported by a large number of packages. We
		// should not need to reload those packages to get a diagnostic.
		{"kubernetes", "pkg/util/hash/hash.go", replace{`"hash"`: `"hashx"`}},
		{"kubernetes", "pkg/kubelet/kubelet.go", replace{
			`"k8s.io/kubernetes/pkg/kubelet/config"`: `"k8s.io/kubernetes/pkg/kubelet/configx"`,
		}},
	}

	for _, test := range tests {
		b.Run(fmt.Sprintf("%s/%s", test.repo, path.Base(test.file)), func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)

			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			env.AfterChange()

			profileName := qualifiedName("reload", test.repo, path.Base(test.file))
			if stopAndRecord := startProfileIfSupported(b, env, profileName); stopAndRecord != nil {
				defer stopAndRecord()
			}

			b.ResetTimer()
			for b.Loop() {
				// Mutate the file. This may result in cache hits, but that's OK: the
				// goal is to ensure that we don't reload more than just the current
				// package.
				for k, v := range test.replace {
					env.RegexpReplace(test.file, regexp.QuoteMeta(k), v)
				}
				// Note: don't use env.AfterChange() here: we only want to await the
				// first diagnostic.
				//
				// Awaiting a full diagnosis would await diagnosing everything, which
				// would require reloading everything.
				env.Await(Diagnostics(ForFile(test.file)))
				for k, v := range test.replace {
					env.RegexpReplace(test.file, regexp.QuoteMeta(v), k)
				}
				env.Await(NoDiagnostics(ForFile(test.file)))
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/rename_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"fmt"
	"testing"
)

func BenchmarkRename(b *testing.B) {
	tests := []struct {
		repo     string
		file     string
		regexp   string
		baseName string
	}{
		{"google-cloud-go", "httpreplay/httpreplay.go", `func (NewRecorder)`, "NewRecorder"},
		{"istio", "pkg/config/model.go", `(Namespace) string`, "Namespace"},
		{"kubernetes", "pkg/controller/lookup_cache.go", `hashutil\.(DeepHashObject)`, "DeepHashObject"},
		{"kuma", "pkg/events/interfaces.go", `Delete`, "Delete"},
		{"pkgsite", "internal/log/log.go", `func (Infof)`, "Infof"},
		{"starlark", "starlark/eval.go", `Program\) (Filename)`, "Filename"},
		{"tools", "internal/lsp/cache/snapshot.go", `meta \*(metadataGraph)`, "metadataGraph"},
	}

	for _, test := range tests {
		names := 0 // bench function may execute multiple times
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			loc := env.RegexpSearch(test.file, test.regexp)
			env.Await(env.DoneWithOpen())
			env.Rename(loc, test.baseName+"X") // pre-warm the query
			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "rename")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				names++
				newName := fmt.Sprintf("%s%d", test.baseName, names)
				env.Rename(loc, newName)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/repo_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"bytes"
	"context"
	"errors"
	"flag"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
	"sync"
	"testing"
	"time"

	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

// repos holds shared repositories for use in benchmarks.
//
// These repos were selected to represent a variety of different types of
// codebases.
var repos = map[string]*repo{
	// google-cloud-go has 145 workspace modules (!), and is quite large.
	"google-cloud-go": {
		name:   "google-cloud-go",
		url:    "https://github.com/googleapis/google-cloud-go.git",
		commit: "07da765765218debf83148cc7ed8a36d6e8921d5",
		inDir:  flag.String("cloud_go_dir", "", "if set, reuse this directory as google-cloud-go@07da7657"),
	},

	// Used by x/benchmarks; large.
	"istio": {
		name:   "istio",
		url:    "https://github.com/istio/istio",
		commit: "1.17.0",
		inDir:  flag.String("istio_dir", "", "if set, reuse this directory as istio@v1.17.0"),
	},

	// Kubernetes is a large repo with many dependencies, and in the past has
	// been about as large a repo as gopls could handle.
	"kubernetes": {
		name:   "kubernetes",
		url:    "https://github.com/kubernetes/kubernetes",
		commit: "v1.24.0",
		short:  true,
		inDir:  flag.String("kubernetes_dir", "", "if set, reuse this directory as kubernetes@v1.24.0"),
	},

	// A large, industrial application.
	"kuma": {
		name:   "kuma",
		url:    "https://github.com/kumahq/kuma",
		commit: "2.1.1",
		inDir:  flag.String("kuma_dir", "", "if set, reuse this directory as kuma@v2.1.1"),
	},

	// A repo containing a very large package (./dataintegration).
	"oracle": {
		name:   "oracle",
		url:    "https://github.com/oracle/oci-go-sdk.git",
		commit: "v65.43.0",
		short:  true,
		inDir:  flag.String("oracle_dir", "", "if set, reuse this directory as oracle/oci-go-sdk@v65.43.0"),
	},

	// x/pkgsite is familiar and represents a common use case (a webserver). It
	// also has a number of static non-go files and template files.
	"pkgsite": {
		name:   "pkgsite",
		url:    "https://go.googlesource.com/pkgsite",
		commit: "81f6f8d4175ad0bf6feaa03543cc433f8b04b19b",
		short:  true,
		inDir:  flag.String("pkgsite_dir", "", "if set, reuse this directory as pkgsite@81f6f8d4"),
	},

	// A tiny self-contained project.
	"starlark": {
		name:   "starlark",
		url:    "https://github.com/google/starlark-go",
		commit: "3f75dec8e4039385901a30981e3703470d77e027",
		short:  true,
		inDir:  flag.String("starlark_dir", "", "if set, reuse this directory as starlark@3f75dec8"),
	},

	// The current repository, which is medium-small and has very few dependencies.
	"tools": {
		name:   "tools",
		url:    "https://go.googlesource.com/tools",
		commit: "gopls/v0.9.0",
		short:  true,
		inDir:  flag.String("tools_dir", "", "if set, reuse this directory as x/tools@v0.9.0"),
	},

	// A repo of similar size to kubernetes, but with substantially more
	// complex types that led to a serious performance regression (issue #60621).
	"hashiform": {
		name:   "hashiform",
		url:    "https://github.com/hashicorp/terraform-provider-aws",
		commit: "ac55de2b1950972d93feaa250d7505d9ed829c7c",
		inDir:  flag.String("hashiform_dir", "", "if set, reuse this directory as hashiform@ac55de2"),
	},
}

// getRepo gets the requested repo, and skips the test if -short is set and
// repo is not configured as a short repo.
//
// The name may include an optional ".foo" suffix after the repo
// identifier. This allows several tests to use the same repo but have
// distinct test names and associated file names.
func getRepo(tb testing.TB, name string) *repo {
	tb.Helper()
	name, _, _ = strings.Cut(name, ".") // remove ".foo" suffix
	repo := repos[name]
	if repo == nil {
		tb.Fatalf("repo %s does not exist", name)
	}
	if !repo.short && testing.Short() {
		tb.Skipf("large repo %s does not run with -short", repo.name)
	}
	return repo
}

// A repo represents a working directory for a repository checked out at a
// specific commit.
//
// Repos are used for sharing state across benchmarks that operate on the same
// codebase.
type repo struct {
	// static configuration
	name   string  // must be unique, used for subdirectory
	url    string  // repo url
	commit string  // full commit hash or tag
	short  bool    // whether this repo runs with -short
	inDir  *string // if set, use this dir as url@commit, and don't delete

	dirOnce sync.Once
	dir     string // directory containing source code checked out to url@commit

	// shared editor state
	editorOnce sync.Once
	editor     *fake.Editor
	sandbox    *fake.Sandbox
	awaiter    *Awaiter
}

// reusableDir return a reusable directory for benchmarking, or "".
//
// If the user specifies a directory, the test will create and populate it
// on the first run and re-use it on subsequent runs. Otherwise it will
// create, populate, and delete a temporary directory.
func (r *repo) reusableDir() string {
	if r.inDir == nil {
		return ""
	}
	return *r.inDir
}

// getDir returns directory containing repo source code, creating it if
// necessary. It is safe for concurrent use.
func (r *repo) getDir() string {
	r.dirOnce.Do(func() {
		if r.dir = r.reusableDir(); r.dir == "" {
			r.dir = filepath.Join(getTempDir(), r.name)
		}

		_, err := os.Stat(r.dir)
		switch {
		case os.IsNotExist(err):
			log.Printf("cloning %s@%s into %s", r.url, r.commit, r.dir)
			if err := shallowClone(r.dir, r.url, r.commit); err != nil {
				log.Fatal(err)
			}
		case err != nil:
			log.Fatal(err)
		default:
			log.Printf("reusing %s as %s@%s", r.dir, r.url, r.commit)
		}
	})
	return r.dir
}

// sharedEnv returns a shared benchmark environment. It is safe for concurrent
// use.
//
// Every call to sharedEnv uses the same editor and sandbox, as a means to
// avoid reinitializing the editor for large repos. Calling repo.Close cleans
// up the shared environment.
//
// Repos in the package-local Repos var are closed at the end of the test main
// function.
func (r *repo) sharedEnv(tb testing.TB) *Env {
	r.editorOnce.Do(func() {
		dir := r.getDir()

		start := time.Now()
		log.Printf("starting initial workspace load for %s", r.name)
		ts, err := newGoplsConnector(profileArgs(r.name, false))
		if err != nil {
			log.Fatal(err)
		}
		r.sandbox, r.editor, r.awaiter, err = connectEditor(dir, fake.EditorConfig{}, ts)
		if err != nil {
			log.Fatalf("connecting editor: %v", err)
		}

		if err := r.awaiter.Await(context.Background(), InitialWorkspaceLoad); err != nil {
			log.Fatal(err)
		}
		log.Printf("initial workspace load (cold) for %s took %v", r.name, time.Since(start))
	})

	return &Env{
		TB:      tb,
		Ctx:     context.Background(),
		Editor:  r.editor,
		Sandbox: r.sandbox,
		Awaiter: r.awaiter,
	}
}

// newEnv returns a new Env connected to a new gopls process communicating
// over stdin/stdout. It is safe for concurrent use.
//
// It is the caller's responsibility to call Close on the resulting Env when it
// is no longer needed.
func (r *repo) newEnv(tb testing.TB, config fake.EditorConfig, forOperation string, cpuProfile bool) *Env {
	dir := r.getDir()

	args := profileArgs(qualifiedName(r.name, forOperation), cpuProfile)
	ts, err := newGoplsConnector(args)
	if err != nil {
		tb.Fatal(err)
	}
	sandbox, editor, awaiter, err := connectEditor(dir, config, ts)
	if err != nil {
		log.Fatalf("connecting editor: %v", err)
	}

	return &Env{
		TB:      tb,
		Ctx:     context.Background(),
		Editor:  editor,
		Sandbox: sandbox,
		Awaiter: awaiter,
	}
}

// Close cleans up shared state referenced by the repo.
func (r *repo) Close() error {
	var errBuf bytes.Buffer
	if r.editor != nil {
		if err := r.editor.Close(context.Background()); err != nil {
			fmt.Fprintf(&errBuf, "closing editor: %v", err)
		}
	}
	if r.sandbox != nil {
		if err := r.sandbox.Close(); err != nil {
			fmt.Fprintf(&errBuf, "closing sandbox: %v", err)
		}
	}
	if r.dir != "" && r.reusableDir() == "" {
		if err := os.RemoveAll(r.dir); err != nil {
			fmt.Fprintf(&errBuf, "cleaning dir: %v", err)
		}
	}
	if errBuf.Len() > 0 {
		return errors.New(errBuf.String())
	}
	return nil
}

// cleanup cleans up state that is shared across benchmark functions.
func cleanup() error {
	var errBuf bytes.Buffer
	for _, repo := range repos {
		if err := repo.Close(); err != nil {
			fmt.Fprintf(&errBuf, "closing %q: %v", repo.name, err)
		}
	}
	if tempDir != "" {
		if err := os.RemoveAll(tempDir); err != nil {
			fmt.Fprintf(&errBuf, "cleaning tempDir: %v", err)
		}
	}
	if errBuf.Len() > 0 {
		return errors.New(errBuf.String())
	}
	return nil
}


================================================
FILE: gopls/internal/test/integration/bench/stress_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"context"
	"flag"
	"fmt"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
)

// github.com/pilosa/pilosa is a repository that has historically caused
// significant memory problems for Gopls. We use it for a simple stress test
// that types arbitrarily in a file with lots of dependents.

var pilosaPath = flag.String("pilosa_path", "", "Path to a directory containing "+
	"github.com/pilosa/pilosa, for stress testing. Do not set this unless you "+
	"know what you're doing!")

func TestPilosaStress(t *testing.T) {
	// TODO(rfindley): revisit this test and make it is hermetic: it should check
	// out pilosa into a directory.
	//
	// Note: This stress test has not been run recently, and may no longer
	// function properly.
	if *pilosaPath == "" {
		t.Skip("-pilosa_path not configured")
	}

	sandbox, err := fake.NewSandbox(&fake.SandboxConfig{
		Workdir: *pilosaPath,
		GOPROXY: "https://proxy.golang.org",
	})
	if err != nil {
		t.Fatal(err)
	}
	server := lsprpc.NewStreamServer(cache.New(nil), false, nil)
	ts := servertest.NewPipeServer(server, jsonrpc2.NewRawStream)

	ctx := context.Background()
	editor, err := fake.NewEditor(sandbox, fake.EditorConfig{}).Connect(ctx, ts, fake.ClientHooks{})
	if err != nil {
		t.Fatal(err)
	}

	files := []string{
		"cmd.go",
		"internal/private.pb.go",
		"roaring/roaring.go",
		"roaring/roaring_internal_test.go",
		"server/handler_test.go",
	}
	for _, file := range files {
		if err := editor.OpenFile(ctx, file); err != nil {
			t.Fatal(err)
		}
	}
	ctx, cancel := context.WithTimeout(ctx, 10*time.Minute)
	defer cancel()

	i := 1
	// MagicNumber is an identifier that occurs in roaring.go. Just change it
	// arbitrarily.
	if err := editor.RegexpReplace(ctx, "roaring/roaring.go", "MagicNumber", fmt.Sprintf("MagicNumber%d", 1)); err != nil {
		t.Fatal(err)
	}
	for {
		select {
		case <-ctx.Done():
			return
		default:
		}
		if err := editor.RegexpReplace(ctx, "roaring/roaring.go", fmt.Sprintf("MagicNumber%d", i), fmt.Sprintf("MagicNumber%d", i+1)); err != nil {
			t.Fatal(err)
		}
		// Simulate (very fast) typing.
		//
		// Typing 80 wpm ~150ms per keystroke.
		time.Sleep(150 * time.Millisecond)
		i++
	}
}


================================================
FILE: gopls/internal/test/integration/bench/tests_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package bench

import (
	"encoding/json"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration"
)

func BenchmarkPackagesCommand(b *testing.B) {
	// By convention, x/benchmarks runs the gopls benchmarks with -short, so that
	// we can use this flag to filter out benchmarks that should not be run by
	// the perf builder.
	//
	// In this case, the benchmark must be skipped because the current baseline
	// (gopls@v0.11.0) lacks the gopls.package command.
	if testing.Short() {
		b.Skip("not supported by the benchmark dashboard baseline")
	}

	tests := []struct {
		repo    string
		files   []string
		recurse bool
	}{
		{"tools", []string{"internal/lsp/debounce_test.go"}, false},
	}
	for _, test := range tests {
		b.Run(test.repo, func(b *testing.B) {
			args := command.PackagesArgs{
				Mode: command.NeedTests,
			}

			env := getRepo(b, test.repo).sharedEnv(b)
			for _, file := range test.files {
				env.OpenFile(file)
				defer closeBuffer(b, env, file)
				args.Files = append(args.Files, env.Editor.DocumentURI(file))
			}
			env.AfterChange()

			result := executePackagesCmd(b, env, args) // pre-warm

			// sanity check JSON {en,de}coding
			var pkgs command.PackagesResult
			data, err := json.Marshal(result)
			if err != nil {
				b.Fatal(err)
			}
			err = json.Unmarshal(data, &pkgs)
			if err != nil {
				b.Fatal(err)
			}
			var haveTest bool
			for _, pkg := range pkgs.Packages {
				for _, file := range pkg.TestFiles {
					if len(file.Tests) > 0 {
						haveTest = true
						break
					}
				}
			}
			if !haveTest {
				b.Fatalf("Expected tests")
			}

			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "packages")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				executePackagesCmd(b, env, args)
			}
		})
	}
}

func executePackagesCmd(t testing.TB, env *integration.Env, args command.PackagesArgs) any {
	t.Helper()
	cmd := command.NewPackagesCommand("Packages", args)
	result, err := env.Editor.Server.ExecuteCommand(env.Ctx, &protocol.ExecuteCommandParams{
		Command:   command.Packages.String(),
		Arguments: cmd.Arguments,
	})
	if err != nil {
		t.Fatal(err)
	}
	return result
}


================================================
FILE: gopls/internal/test/integration/bench/typing_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"fmt"
	"sync/atomic"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
)

// BenchmarkTyping simulates typing steadily in a single file at different
// paces.
//
// The key metric for this benchmark is not latency, but cpu_seconds per
// operation.
func BenchmarkTyping(b *testing.B) {
	for _, test := range didChangeTests {
		b.Run(test.repo, func(b *testing.B) {
			env := getRepo(b, test.repo).sharedEnv(b)
			env.OpenFile(test.file)
			defer closeBuffer(b, env, test.file)

			// Insert the text we'll be modifying at the top of the file.
			env.EditBuffer(test.file, protocol.TextEdit{NewText: "// __TEST_PLACEHOLDER_0__\n"})
			env.AfterChange()

			delays := []time.Duration{
				10 * time.Millisecond,  // automated changes
				50 * time.Millisecond,  // very fast mashing, or fast key sequences
				150 * time.Millisecond, // avg interval for 80wpm typing.
			}

			for _, delay := range delays {
				b.Run(delay.String(), func(b *testing.B) {
					if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(test.repo, "typing")); stopAndRecord != nil {
						defer stopAndRecord()
					}
					ticker := time.NewTicker(delay)
					for b.Loop() {
						edits := atomic.AddInt64(&editID, 1)
						env.EditBuffer(test.file, protocol.TextEdit{
							Range: protocol.Range{
								Start: protocol.Position{Line: 0, Character: 0},
								End:   protocol.Position{Line: 1, Character: 0},
							},
							// Increment the placeholder text, to ensure cache misses.
							NewText: fmt.Sprintf("// __TEST_PLACEHOLDER_%d__\n", edits),
						})
						<-ticker.C
					}
					b.StopTimer()
					ticker.Stop()
					env.AfterChange() // wait for all change processing to complete
				})
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/bench/unimported_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"context"
	"fmt"
	"go/token"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/modindex"
)

// This code is designed to show the comparative effectiveness
// of the current and the old ways of doing unimported completions.
// It should only be run by hand when there is an existing module
// cache and module cache index. It compares the two algorithms
// for various values of the completion budget. "gopls" is the
// current algorithm, "goimports" is the old one. [On my workstation
// the old algorithms occasionally fails to find the completion,
// and when it does it is more than 10 times slower.]
func BenchmarkLocalModcache(b *testing.B) {
	b.Skip("only run by hand")
	budgets := []string{"0s", "100ms", "200ms", "500ms", "1s", "5s"}
	sources := []string{"gopls", "goimports"}
	for _, budget := range budgets {
		b.Run(fmt.Sprintf("budget=%s", budget), func(b *testing.B) {
			for _, source := range sources {
				b.Run(fmt.Sprintf("source=%s", source), func(b *testing.B) {
					runModcacheCompletion(b, budget, source)
				})
			}
		})
	}
}

func runModcacheCompletion(b *testing.B, budget, source string) {
	// First set up the program to be edited
	gomod := `
module mod.com

go 1.21
`
	pat := `
package main
var _ = %s.%s
`
	pkg, name, modcache := findSym(b)
	name, _, _ = strings.Cut(name, " ")
	mainfile := fmt.Sprintf(pat, pkg, name)
	// Second, create the Env and start gopls
	dir := getTempDir()
	if err := os.Mkdir(dir, 0750); err != nil {
		if !os.IsExist(err) {
			b.Fatal(err)
		}
	}
	defer os.RemoveAll(dir) // is this right? needed?
	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte(gomod), 0644); err != nil {
		b.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "main.go"), []byte(mainfile), 0644); err != nil {
		b.Fatal(err)
	}
	ts, err := newGoplsConnector(nil)
	if err != nil {
		b.Fatal(err)
	}
	// PJW: put better EditorConfig here
	envvars := map[string]string{
		"GOMODCACHE": modcache,
		//"GOPATH":     sandbox.GOPATH(), // do we need a GOPATH?
	}
	fc := fake.EditorConfig{
		Env: envvars,
		Settings: map[string]any{
			"completeUnimported": true,
			"completionBudget":   budget, // "0s", "100ms"
			"importsSource":      source, // "gopls" or "goimports"
		},
	}
	sandbox, editor, awaiter, err := connectEditor(dir, fc, ts)
	if err != nil {
		b.Fatal(err)
	}
	defer sandbox.Close()
	defer editor.Close(context.Background())
	if err := awaiter.Await(context.Background(), InitialWorkspaceLoad); err != nil {
		b.Fatal(err)
	}
	env := &Env{
		TB:      b,
		Ctx:     context.Background(),
		Editor:  editor,
		Sandbox: sandbox,
		Awaiter: awaiter,
	}
	// Check that completion works as expected
	env.CreateBuffer("main.go", mainfile)
	env.AfterChange()
	loc := env.RegexpSearch("main.go", name)
	completions := env.Completion(loc)
	if len(completions.Items) == 0 {
		b.Error("no completions")
	}

	// run benchmark
	for b.Loop() {
		loc := env.RegexpSearch("main.go", name)
		env.Completion(loc)
	}
}

// find some symbol in the module cache
func findSym(t testing.TB) (pkg, name, gomodcache string) {
	initForTest(t) // set modindex.IndexDir
	cmd := exec.Command("go", "env", "GOMODCACHE")
	out, err := cmd.Output()
	if err != nil {
		t.Fatal(err)
	}
	modcache := strings.TrimSpace(string(out))
	ix, err := modindex.Read(modcache)
	if err != nil {
		t.Fatal(err)
	}
	if ix == nil {
		t.Fatal("nil index")
	}
	// find some symbol in the module cache
	nth := 100 // or something
	for _, e := range ix.Entries {
		if token.IsExported(e.PkgName) || strings.HasPrefix(e.PkgName, "_") {
			continue // weird stuff in module cache
		}

		for _, nm := range e.Names {
			nth--
			if nth == 0 {
				return e.PkgName, nm, modcache
			}
		}
	}
	t.Fatalf("index doesn't have enough usable names, need another %d", nth)
	return "", "", modcache
}

// Set IndexDir, avoiding the special case for tests,
func initForTest(t testing.TB) {
	dir, err := os.UserCacheDir()
	if err != nil {
		t.Fatalf("os.UserCacheDir: %v", err)
	}
	dir = filepath.Join(dir, "goimports")
	modindex.IndexDir = dir
}


================================================
FILE: gopls/internal/test/integration/bench/workspace_symbols_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bench

import (
	"flag"
	"fmt"
	"testing"
	"time"
)

var symbolQuery = flag.String("symbol_query", "test", "symbol query to use in benchmark")

// BenchmarkWorkspaceSymbols benchmarks the time to execute a workspace symbols
// request (controlled by the -symbol_query flag).
func BenchmarkWorkspaceSymbols(b *testing.B) {
	for name := range repos {
		b.Run(name, func(b *testing.B) {
			env := getRepo(b, name).sharedEnv(b)
			start := time.Now()
			symbols := env.Symbol(*symbolQuery) // warm the cache

			if testing.Verbose() {
				fmt.Printf("Results (after %s):\n", time.Since(start))
				for i, symbol := range symbols {
					fmt.Printf("\t%d. %s (%s)\n", i, symbol.Name, symbol.ContainerName)
				}
			}

			b.ResetTimer()

			if stopAndRecord := startProfileIfSupported(b, env, qualifiedName(name, "workspaceSymbols")); stopAndRecord != nil {
				defer stopAndRecord()
			}

			for b.Loop() {
				env.Symbol(*symbolQuery)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/codelens/codelens_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package codelens

import (
	"fmt"
	"os"
	"testing"

	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

func TestDisablingCodeLens(t *testing.T) {
	const workspace = `
-- go.mod --
module codelens.test

go 1.12
-- lib.go --
package lib

type Number int

const (
	Zero Number = iota
	One
	Two
)

//` + `go:generate stringer -type=Number
`
	tests := []struct {
		label        string
		enabled      map[string]bool
		wantCodeLens bool
	}{
		{
			label:        "default",
			wantCodeLens: true,
		},
		{
			label:        "generate disabled",
			enabled:      map[string]bool{string(settings.CodeLensGenerate): false},
			wantCodeLens: false,
		},
	}
	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			WithOptions(
				Settings{"codelenses": test.enabled},
			).Run(t, workspace, func(t *testing.T, env *Env) {
				env.OpenFile("lib.go")
				lens := env.CodeLens("lib.go")
				if gotCodeLens := len(lens) > 0; gotCodeLens != test.wantCodeLens {
					t.Errorf("got codeLens: %t, want %t", gotCodeLens, test.wantCodeLens)
				}
			})
		})
	}
}

const proxyWithLatest = `
-- golang.org/x/hello@v1.3.3/go.mod --
module golang.org/x/hello

go 1.12
-- golang.org/x/hello@v1.3.3/hi/hi.go --
package hi

var Goodbye error
-- golang.org/x/hello@v1.2.3/go.mod --
module golang.org/x/hello

go 1.12
-- golang.org/x/hello@v1.2.3/hi/hi.go --
package hi

var Goodbye error
`

// This test confirms the full functionality of the code lenses for updating
// dependencies in a go.mod file, when using a go.work file. It checks for the
// code lens that suggests an update and then executes the command associated
// with that code lens. A regression test for golang/go#39446. It also checks
// that these code lenses only affect the diagnostics and contents of the
// containing go.mod file.
func TestUpgradeCodelens_Workspace(t *testing.T) {
	const shouldUpdateDep = `
-- go.work --
go 1.18

use (
	./a
	./b
)
-- a/go.mod --
module mod.com/a

go 1.14

require golang.org/x/hello v1.2.3
-- a/go.sum --
golang.org/x/hello v1.2.3 h1:7Wesfkx/uBd+eFgPrq0irYj/1XfmbvLV8jZ/W7C2Dwg=
golang.org/x/hello v1.2.3/go.mod h1:OgtlzsxVMUUdsdQCIDYgaauCTH47B8T8vofouNJfzgY=
-- a/main.go --
package main

import "golang.org/x/hello/hi"

func main() {
	_ = hi.Goodbye
}
-- b/go.mod --
module mod.com/b

go 1.14

require golang.org/x/hello v1.2.3
-- b/go.sum --
golang.org/x/hello v1.2.3 h1:7Wesfkx/uBd+eFgPrq0irYj/1XfmbvLV8jZ/W7C2Dwg=
golang.org/x/hello v1.2.3/go.mod h1:OgtlzsxVMUUdsdQCIDYgaauCTH47B8T8vofouNJfzgY=
-- b/main.go --
package main

import (
	"golang.org/x/hello/hi"
)

func main() {
	_ = hi.Goodbye
}
`

	const wantGoModA = `module mod.com/a

go 1.14

require golang.org/x/hello v1.3.3
`
	// Applying the diagnostics or running the codelenses for a/go.mod
	// should not change the contents of b/go.mod
	const wantGoModB = `module mod.com/b

go 1.14

require golang.org/x/hello v1.2.3
`

	for _, commandTitle := range []string{
		"Upgrade transitive dependencies",
		"Upgrade direct dependencies",
	} {
		t.Run(commandTitle, func(t *testing.T) {
			WithOptions(
				ProxyFiles(proxyWithLatest),
			).Run(t, shouldUpdateDep, func(t *testing.T, env *Env) {
				env.OpenFile("a/go.mod")
				env.OpenFile("b/go.mod")
				var lens protocol.CodeLens
				var found bool
				for _, l := range env.CodeLens("a/go.mod") {
					if l.Command.Title == commandTitle {
						lens = l
						found = true
					}
				}
				if !found {
					t.Fatalf("found no command with the title %s", commandTitle)
				}
				if err := env.Editor.ExecuteCommand(env.Ctx, &protocol.ExecuteCommandParams{
					Command:   lens.Command.Command,
					Arguments: lens.Command.Arguments,
				}, nil); err != nil {
					t.Fatal(err)
				}
				env.AfterChange()
				if got := env.BufferText("a/go.mod"); got != wantGoModA {
					t.Fatalf("a/go.mod upgrade failed:\n%s", compare.Text(wantGoModA, got))
				}
				if got := env.BufferText("b/go.mod"); got != wantGoModB {
					t.Fatalf("b/go.mod changed unexpectedly:\n%s", compare.Text(wantGoModB, got))
				}
			})
		})
	}
	for _, vendoring := range []bool{false, true} {
		t.Run(fmt.Sprintf("Upgrade individual dependency vendoring=%v", vendoring), func(t *testing.T) {
			WithOptions(
				ProxyFiles(proxyWithLatest),
			).Run(t, shouldUpdateDep, func(t *testing.T, env *Env) {
				if vendoring {
					env.RunGoCommandInDirWithEnv("a", []string{"GOWORK=off"}, "mod", "vendor")
				}
				env.AfterChange()
				env.OpenFile("a/go.mod")
				env.OpenFile("b/go.mod")

				env.ExecuteCodeLensCommand("a/go.mod", command.CheckUpgrades, nil)
				d := &protocol.PublishDiagnosticsParams{}
				env.OnceMet(
					CompletedWork(server.DiagnosticWorkTitle(server.FromCheckUpgrades), 1, true),
					Diagnostics(env.AtRegexp("a/go.mod", `require`), WithMessage("can be upgraded")),
					ReadDiagnostics("a/go.mod", d),
					// We do not want there to be a diagnostic for b/go.mod,
					// but there may be some subtlety in timing here, where this
					// should always succeed, but may not actually test the correct
					// behavior.
					NoDiagnostics(env.AtRegexp("b/go.mod", `require`)),
				)
				// Check for upgrades in b/go.mod and then clear them.
				env.ExecuteCodeLensCommand("b/go.mod", command.CheckUpgrades, nil)
				env.OnceMet(
					CompletedWork(server.DiagnosticWorkTitle(server.FromCheckUpgrades), 2, true),
					Diagnostics(env.AtRegexp("b/go.mod", `require`), WithMessage("can be upgraded")),
				)
				env.ExecuteCodeLensCommand("b/go.mod", command.ResetGoModDiagnostics, nil)
				env.OnceMet(
					CompletedWork(server.DiagnosticWorkTitle(server.FromResetGoModDiagnostics), 1, true),
					NoDiagnostics(ForFile("b/go.mod")),
				)

				// Apply the diagnostics to a/go.mod.
				env.ApplyQuickFixes("a/go.mod", d.Diagnostics)
				env.AfterChange()
				if got := env.BufferText("a/go.mod"); got != wantGoModA {
					t.Fatalf("a/go.mod upgrade failed:\n%s", compare.Text(wantGoModA, got))
				}
				if got := env.BufferText("b/go.mod"); got != wantGoModB {
					t.Fatalf("b/go.mod changed unexpectedly:\n%s", compare.Text(wantGoModB, got))
				}
			})
		})
	}
}

func TestUpgradeCodelens_ModVendor(t *testing.T) {
	// This test checks the regression of golang/go#66055. The upgrade codelens
	// should work in a mod vendor context (the test above using a go.work file
	// was not broken).
	testenv.NeedsGoCommand1Point(t, 22)

	const shouldUpdateDep = `
-- go.mod --
module mod.com/a

go 1.22

require golang.org/x/hello v1.2.3
-- main.go --
package main

import "golang.org/x/hello/hi"

func main() {
	_ = hi.Goodbye
}
`

	const wantGoModA = `module mod.com/a

go 1.22

require golang.org/x/hello v1.3.3
`

	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxyWithLatest),
	).Run(t, shouldUpdateDep, func(t *testing.T, env *Env) {
		env.RunGoCommand("mod", "vendor")
		env.AfterChange()
		env.OpenFile("go.mod")

		env.ExecuteCodeLensCommand("go.mod", command.CheckUpgrades, nil)
		d := &protocol.PublishDiagnosticsParams{}
		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromCheckUpgrades), 1, true),
			Diagnostics(env.AtRegexp("go.mod", `require`), WithMessage("can be upgraded")),
			ReadDiagnostics("go.mod", d),
		)

		// Apply the diagnostics to a/go.mod.
		env.ApplyQuickFixes("go.mod", d.Diagnostics)
		env.AfterChange()
		if got := env.BufferText("go.mod"); got != wantGoModA {
			t.Fatalf("go.mod upgrade failed:\n%s", compare.Text(wantGoModA, got))
		}
	})
}

func TestUnusedDependenciesCodelens(t *testing.T) {
	const proxy = `
-- golang.org/x/hello@v1.0.0/go.mod --
module golang.org/x/hello

go 1.14
-- golang.org/x/hello@v1.0.0/hi/hi.go --
package hi

var Goodbye error
-- golang.org/x/unused@v1.0.0/go.mod --
module golang.org/x/unused

go 1.14
-- golang.org/x/unused@v1.0.0/nouse/nouse.go --
package nouse

var NotUsed error
`

	const shouldRemoveDep = `
-- go.mod --
module mod.com

go 1.14

require golang.org/x/hello v1.0.0
require golang.org/x/unused v1.0.0

// EOF
-- main.go --
package main

import "golang.org/x/hello/hi"

func main() {
	_ = hi.Goodbye
}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
	).Run(t, shouldRemoveDep, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.RegexpReplace("go.mod", "// EOF", "// EOF unsaved edit") // unsaved edits ok
		env.ExecuteCodeLensCommand("go.mod", command.Tidy, nil)
		env.AfterChange()
		got := env.BufferText("go.mod")
		const wantGoMod = `module mod.com

go 1.14

require golang.org/x/hello v1.0.0

// EOF unsaved edit
`
		if got != wantGoMod {
			t.Fatalf("go.mod tidy failed:\n%s", compare.Text(wantGoMod, got))
		}
	})
}

func TestRegenerateCgo(t *testing.T) {
	testenv.NeedsTool(t, "cgo")
	const workspace = `
-- go.mod --
module example.com

go 1.12
-- cgo.go --
package x

/*
int fortythree() { return 42; }
*/
import "C"

func Foo() {
	print(C.fortytwo())
}
`
	Run(t, workspace, func(t *testing.T, env *Env) {
		// Open the file. We have a nonexistant symbol that will break cgo processing.
		env.OpenFile("cgo.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("cgo.go", ``), WithMessage("go list failed to return CompiledGoFiles")),
		)

		// Fix the C function name. We haven't regenerated cgo, so nothing should be fixed.
		env.RegexpReplace("cgo.go", `int fortythree`, "int fortytwo")
		env.SaveBuffer("cgo.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("cgo.go", ``), WithMessage("go list failed to return CompiledGoFiles")),
		)

		// Regenerate cgo, fixing the diagnostic.
		env.ExecuteCodeLensCommand("cgo.go", command.RegenerateCgo, nil)
		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromRegenerateCgo), 1, true),
			NoDiagnostics(ForFile("cgo.go")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/completion/completion18_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

// This file is misnamed; it has no version constraints.
// TODO(adonovan):  fold into completion_test.go

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/internal/testenv"
)

// test generic receivers
func TestGenericReceiver(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main
type SyncMap[K any, V comparable] struct {}
func (s *SyncMap[K,V]) f() {}
type XX[T any] struct {}
type UU[T any] struct {}
func (s SyncMap[XX,string]) g(v UU) {}
`

	tests := []struct {
		pat  string
		want []string
	}{
		{"s .Syn", []string{"SyncMap[K, V]"}},
		{"Map.X", []string{}}, // This is probably wrong, Maybe "XX"?
		{"v U", []string{"UU", "uint", "uint16", "uint32", "uint64", "uint8", "uintptr"}}, // not U[T]
	}
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		for _, tst := range tests {
			loc := env.RegexpSearch("main.go", tst.pat)
			loc.Range.Start.Character += uint32(protocol.UTF16Len([]byte(tst.pat)))
			completions := env.Completion(loc)
			result := compareCompletionLabels(tst.want, completions.Items)
			if result != "" {
				t.Errorf("%s: wanted %v", result, tst.want)
				for i, g := range completions.Items {
					t.Errorf("got %d %s %s", i, g.Label, g.Detail)
				}
			}
		}
	})
}

func TestFuzzFunc(t *testing.T) {
	// The behavior under test is derived from the std module,
	// not the x/tools/internal/stdlib linked into gopls.
	testenv.NeedsGoCommand1Point(t, 25) // go1.25 added TBF.Attr

	// use the example from the package documentation
	modfile := `
-- go.mod --
module mod.com

go 1.25
`
	part0 := `package foo
import "testing"
func FuzzNone(f *testing.F) {
	f.Add(12) // better not find this f.Add
}
func FuzzHex(f *testing.F) {
	for _, seed := range [][]byte{{}, {0}, {9}, {0xa}, {0xf}, {1, 2, 3, 4}} {
		f.Ad`
	part1 := `d(seed)
	}
	f.F`
	part2 := `uzz(func(t *testing.T, in []byte) {
		enc := hex.EncodeToString(in)
		out, err := hex.DecodeString(enc)
		if err != nil {
		  f.Failed()
		}
		if !bytes.Equal(in, out) {
		  t.Fatalf("%v: round trip: %v, %s", in, out, f.Name())
		}
	})
}
`
	data := modfile + `-- a_test.go --
` + part0 + `
-- b_test.go --
` + part0 + part1 + `
-- c_test.go --
` + part0 + part1 + part2

	tests := []struct {
		file string
		pat  string
		want []string
	}{
		// To avoid breaking these assertions as the "testing" package evolves,
		// use an optional (?) suffix for newer symbols.
		{"a_test.go", "f.A()d", []string{"Add", "ArtifactDir?", "Attr"}}, // Attr is 1.25, Artifact is 1.26
		{"c_test.go", " f.F()", []string{"Failed"}},
		{"c_test.go", "f.N()", []string{"Name"}},
		{"b_test.go", "f.F()", []string{"Fuzz(func(t *testing.T, a []byte)", "Fail", "FailNow",
			"Failed", "Fatal", "Fatalf"}},
	}
	Run(t, data, func(t *testing.T, env *Env) {
		for _, test := range tests {
			env.OpenFile(test.file)
			env.Await(env.DoneWithOpen())
			loc := env.RegexpSearch(test.file, test.pat)
			completions := env.Completion(loc)
			result := compareCompletionLabels(test.want, completions.Items)
			if result != "" {
				t.Errorf("pat=%q <<%s>>", test.pat, result)
				for i, it := range completions.Items {
					t.Errorf("%d got %q %q", i, it.Label, it.Detail)
				}
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/completion/completion_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"fmt"
	"os"
	"path/filepath"
	"slices"
	"sort"
	"strings"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/telemetry/counter"
	"golang.org/x/telemetry/counter/countertest"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/modindex"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/blah/blah.go --
package hello

const Name = "Hello"
`

func TestPackageCompletion(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- cmd/main.go --
package main
-- cmd/testfile.go --
package
-- fruits/apple.go --
package apple

fun apple() int {
	return 0
}

-- fruits/testfile.go --
// this is a comment

/*
 this is a multiline comment
*/

import "fmt"

func test() {}

-- fruits/testfile2.go --
package

-- fruits/testfile3.go --
pac
-- 123f_r.u~its-123/testfile.go --
package

-- .invalid-dir@-name/testfile.go --
package
`
	var (
		testfile4 = ""
		testfile5 = "/*a comment*/ "
		testfile6 = "/*a comment*/\n"
	)
	for _, tc := range []struct {
		name          string
		filename      string
		content       *string
		triggerRegexp string
		want          []string
		editRegexp    string
	}{
		{
			name:          "main package completion after package keyword",
			filename:      "cmd/testfile.go",
			triggerRegexp: "package()",
			want:          []string{"package main", "package cmd", "package cmd_test"},
			editRegexp:    "package",
		},
		{
			name:          "package completion at valid position",
			filename:      "fruits/testfile.go",
			triggerRegexp: "\n()",
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    "\n()",
		},
		{
			name:          "package completion in a comment",
			filename:      "fruits/testfile.go",
			triggerRegexp: "th()is",
			want:          nil,
		},
		{
			name:          "package completion in a multiline comment",
			filename:      "fruits/testfile.go",
			triggerRegexp: `\/\*\n()`,
			want:          nil,
		},
		{
			name:          "package completion at invalid position",
			filename:      "fruits/testfile.go",
			triggerRegexp: "import \"fmt\"\n()",
			want:          nil,
		},
		{
			name:          "package completion after package keyword",
			filename:      "fruits/testfile2.go",
			triggerRegexp: "package()",
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    "package",
		},
		{
			name:          "package completion with 'pac' prefix",
			filename:      "fruits/testfile3.go",
			triggerRegexp: "pac()",
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    "pac",
		},
		{
			name:          "package completion for empty file",
			filename:      "fruits/testfile4.go",
			triggerRegexp: "^$",
			content:       &testfile4,
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    "^$",
		},
		{
			name:          "package completion without terminal newline",
			filename:      "fruits/testfile5.go",
			triggerRegexp: `\*\/ ()`,
			content:       &testfile5,
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    `\*\/ ()`,
		},
		{
			name:          "package completion on terminal newline",
			filename:      "fruits/testfile6.go",
			triggerRegexp: `\*\/\n()`,
			content:       &testfile6,
			want:          []string{"package apple", "package apple_test", "package fruits", "package fruits_test", "package main"},
			editRegexp:    `\*\/\n()`,
		},
		// Issue golang/go#44680
		{
			name:          "package completion for dir name with punctuation",
			filename:      "123f_r.u~its-123/testfile.go",
			triggerRegexp: "package()",
			want:          []string{"package fruits123", "package fruits123_test", "package main"},
			editRegexp:    "package",
		},
		{
			name:          "package completion for invalid dir name",
			filename:      ".invalid-dir@-name/testfile.go",
			triggerRegexp: "package()",
			want:          []string{"package main"},
			editRegexp:    "package",
		},
	} {
		t.Run(tc.name, func(t *testing.T) {
			Run(t, files, func(t *testing.T, env *Env) {
				if tc.content != nil {
					env.WriteWorkspaceFile(tc.filename, *tc.content)
					env.Await(env.DoneWithChangeWatchedFiles())
				}
				env.OpenFile(tc.filename)
				completions := env.Completion(env.RegexpSearch(tc.filename, tc.triggerRegexp))

				// Check that the completion item suggestions are in the range
				// of the file. {Start,End}.Line are zero-based.
				lineCount := len(strings.Split(env.BufferText(tc.filename), "\n"))
				for _, item := range completions.Items {
					for _, mode := range []string{"replace", "insert"} {
						edit, err := protocol.SelectCompletionTextEdit(item, mode == "replace")
						if err != nil {
							t.Fatalf("unexpected text edit in completion item (%v): %v", mode, err)
						}
						if start := int(edit.Range.Start.Line); start > lineCount {
							t.Fatalf("unexpected text edit range (%v) start line number: got %d, want <= %d", mode, start, lineCount)
						}
						if end := int(edit.Range.End.Line); end > lineCount {
							t.Fatalf("unexpected text edit range (%v) end line number: got %d, want <= %d", mode, end, lineCount)
						}
					}
				}

				if tc.want != nil {
					expectedLoc := env.RegexpSearch(tc.filename, tc.editRegexp)
					for _, item := range completions.Items {
						for _, mode := range []string{"replace", "insert"} {
							edit, _ := protocol.SelectCompletionTextEdit(item, mode == "replace")
							gotRng := edit.Range
							if expectedLoc.Range != gotRng {
								t.Errorf("unexpected completion range (%v) for completion item %s: got %v, want %v",
									mode, item.Label, gotRng, expectedLoc.Range)
							}
						}
					}
				}

				diff := compareCompletionLabels(tc.want, completions.Items)
				if diff != "" {
					t.Error(diff)
				}
			})
		})
	}
}

func TestPackageNameCompletion(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- math/add.go --
package ma
`

	want := []string{"ma", "ma_test", "main", "math", "math_test"}
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("math/add.go")
		completions := env.Completion(env.RegexpSearch("math/add.go", "package ma()"))

		diff := compareCompletionLabels(want, completions.Items)
		if diff != "" {
			t.Fatal(diff)
		}
	})
}

// compareCompletionLabels returns a non-empty string reporting the
// difference (if any) between the labels of the actual completion
// items (gotItems) and the expected list (want).
//
// A want item with a "?" suffix is optional.
//
// TODO(rfindley): audit/clean up call sites for this helper, to ensure
// consistent test errors.
func compareCompletionLabels(want []string, gotItems []protocol.CompletionItem) string {
	var got []string
	for _, item := range gotItems {
		got = append(got, item.Label)
		if item.Label != item.InsertText && item.TextEdit == nil {
			// Label should be the same as InsertText, if InsertText is to be used
			return fmt.Sprintf("label not the same as InsertText %#v", item)
		}
	}

	if len(got) == 0 && len(want) == 0 {
		return "" // treat nil and the empty slice as equivalent
	}

	// A 'want' item with a '?' suffix is optional, to ease
	// migration across versions. Remove any that are not present
	// in the 'got' set.
	var out []string
	for _, item := range want {
		item, optional := strings.CutSuffix(item, "?")
		if optional && !slices.Contains(got, item) {
			continue // optional item is missing
		}
		out = append(out, item)
	}
	want = out

	if diff := cmp.Diff(want, got); diff != "" {
		return fmt.Sprintf("completion item mismatch (-want +got):\n%s", diff)
	}
	return ""
}

func TestIssue74611(t *testing.T) {
	// Completions should not offer symbols from unimported packages
	// that cannot be imported because they are "internal".
	//
	// Ideally, we should test std case as well but because mocking
	// a fake stdlib is hard, we just test the 3rd user case.
	// std test is done interactively.
	const files = `-- go.mod --
module mod.com/cmd

go 1.21

-- a.go --
package pkg
import "fmt"

func main() {
	fmt.Println("call Println to use fmt")
	_ = maps
} // (completion requested at start of line)
`

	WithOptions().Run(t, files, func(t *testing.T, env *Env) {
		filename := "a.go"
		// Trigger unimported completions for the maps package.
		env.OpenFile(filename)
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch(filename, `()\n\}`)
		completions := env.Completion(loc)
		if len(completions.Items) == 0 {
			t.Fatalf("no completion items")
		}
		runtimeMaps := `"internal/runtime/maps"`
		found := slices.ContainsFunc(completions.Items, func(item protocol.CompletionItem) bool {
			return item.Detail == runtimeMaps
		})

		if found {
			t.Fatalf("unwanted completion: %s", runtimeMaps)
		}
	})
}

func TestUnimportedCompletion(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.14

require example.com v1.2.3
-- main.go --
package main

func main() {
	_ = blah
}
-- main2.go --
package main

import "example.com/blah"

func _() {
	_ = blah.Hello
}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, mod, func(t *testing.T, env *Env) {
		// Make sure the dependency is in the module cache and accessible for
		// unimported completions, and then remove it before proceeding.
		env.RemoveWorkspaceFile("main2.go")
		env.RunGoCommand("mod", "tidy")
		env.Await(env.DoneWithChangeWatchedFiles())

		// Trigger unimported completions for the example.com/blah package.
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("main.go", "()ah")
		completions := env.Completion(loc)
		if len(completions.Items) == 0 {
			t.Fatalf("no completion items")
		}
		env.AcceptCompletion(loc, completions.Items[0]) // adds blah import to main.go
		env.Await(env.DoneWithChange())

		// Trigger completions once again for the blah.<> selector.
		env.RegexpReplace("main.go", "_ = blah", "_ = blah.")
		env.Await(env.DoneWithChange())
		loc = env.RegexpSearch("main.go", `()\n\}`)
		completions = env.Completion(loc)
		if len(completions.Items) != 1 {
			t.Fatalf("expected 1 completion item, got %v", len(completions.Items))
		}
		item := completions.Items[0]
		if item.Label != "Name" {
			t.Fatalf("expected completion item blah.Name, got %v", item.Label)
		}
		env.AcceptCompletion(loc, item)

		// Await the diagnostics to add example.com/blah to the go.mod file.
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", `"example.com/blah"`)),
		)
	})
}

// Test that completions still work with an undownloaded module, golang/go#43333.
func TestUndownloadedModule(t *testing.T) {
	// mod.com depends on example.com, but only in a file that's hidden by a
	// build tag, so the IWL won't download example.com. That will cause errors
	// in the go list -m call performed by the imports package.
	const files = `
-- go.mod --
module mod.com

go 1.14

require example.com v1.2.3
-- useblah.go --
// +build hidden

package pkg
import "example.com/blah"
var _ = blah.Name
-- mainmod/mainmod.go --
package mainmod

const Name = "mainmod"
`
	WithOptions(
		WriteGoSum("."),
		Settings{"importsSource": settings.ImportsSourceGopls},
		ProxyFiles(proxy)).Run(t, files, func(t *testing.T, env *Env) {
		env.CreateBuffer("import.go", "package pkg\nvar _ = mainmod.Name\n")
		env.SaveBuffer("import.go")
		content := env.ReadWorkspaceFile("import.go")
		if !strings.Contains(content, `import "mod.com/mainmod`) {
			t.Errorf("expected import of mod.com/mainmod in %q", content)
		}
	})
}

// Test that we can doctor the source code enough so the file is
// parseable and completion works as expected.
func TestSourceFixup(t *testing.T) {
	// This example relies on the fixer to turn "s." into "s._" so
	// that it parses as a SelectorExpr with only local problems,
	// instead of snarfing up the following declaration of S
	// looking for an identifier; thus completion offers s.i.
	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo.go --
package foo

func _() {
	var s S
	if s.
}

type S struct {
	i int
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		completions := env.Completion(env.RegexpSearch("foo.go", `if s\.()`))
		diff := compareCompletionLabels([]string{"i"}, completions.Items)
		if diff != "" {
			t.Fatal(diff)
		}
	})
}

func TestCompletion_Issue45510(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func _() {
	type a *a
	var aaaa1, aaaa2 a
	var _ a = aaaa

	type b a
	var bbbb1, bbbb2 b
	var _ b = bbbb
}

type (
	c *d
	d *e
	e **c
)

func _() {
	var (
		xxxxc c
		xxxxd d
		xxxxe e
	)

	var _ c = xxxx
	var _ d = xxxx
	var _ e = xxxx
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")

		tests := []struct {
			re   string
			want []string
		}{
			{`var _ a = aaaa()`, []string{"aaaa1", "aaaa2"}},
			{`var _ b = bbbb()`, []string{"bbbb1", "bbbb2"}},
			{`var _ c = xxxx()`, []string{"xxxxc", "xxxxd", "xxxxe"}},
			{`var _ d = xxxx()`, []string{"xxxxc", "xxxxd", "xxxxe"}},
			{`var _ e = xxxx()`, []string{"xxxxc", "xxxxd", "xxxxe"}},
		}
		for _, tt := range tests {
			completions := env.Completion(env.RegexpSearch("main.go", tt.re))
			diff := compareCompletionLabels(tt.want, completions.Items)
			if diff != "" {
				t.Errorf("%s: %s", tt.re, diff)
			}
		}
	})
}

func TestCompletionDeprecation(t *testing.T) {
	const files = `
-- go.mod --
module test.com

go 1.16
-- prog.go --
package waste
// Deprecated: use newFoof.
func fooFunc() bool {
	return false
}

// Deprecated: bad.
const badPi = 3.14

func doit() {
	if fooF
	panic()
	x := badP
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("prog.go")
		loc := env.RegexpSearch("prog.go", "if fooF")
		loc.Range.Start.Character += uint32(protocol.UTF16Len([]byte("if fooF")))
		completions := env.Completion(loc)
		diff := compareCompletionLabels([]string{"fooFunc"}, completions.Items)
		if diff != "" {
			t.Error(diff)
		}
		if completions.Items[0].Tags == nil {
			t.Errorf("expected Tags to show deprecation %#v", completions.Items[0].Tags)
		}
		loc = env.RegexpSearch("prog.go", "= badP")
		loc.Range.Start.Character += uint32(protocol.UTF16Len([]byte("= badP")))
		completions = env.Completion(loc)
		diff = compareCompletionLabels([]string{"badPi"}, completions.Items)
		if diff != "" {
			t.Error(diff)
		}
		if completions.Items[0].Tags == nil {
			t.Errorf("expected Tags to show deprecation %#v", completions.Items[0].Tags)
		}
	})
}

func TestUnimportedCompletion_VSCodeIssue1489(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.14

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("a")
	math.Sqr
}
`
	WithOptions(
		WindowsLineEndings(),
		Settings{"ui.completion.usePlaceholders": true},
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, src, func(t *testing.T, env *Env) {
		// Trigger unimported completions for the mod.com package.
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("main.go", "Sqr()")
		completions := env.Completion(loc)
		if len(completions.Items) == 0 {
			t.Fatalf("no completion items")
		}
		env.AcceptCompletion(loc, completions.Items[0])
		env.Await(env.DoneWithChange())
		got := env.BufferText("main.go")
		want := "package main\r\n\r\nimport (\r\n\t\"fmt\"\r\n\t\"math\"\r\n)\r\n\r\nfunc main() {\r\n\tfmt.Println(\"a\")\r\n\tmath.Sqrt(${1:x float64})\r\n}\r\n"
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("unimported completion (-want +got):\n%s", diff)
		}
	})
}

func TestUnimportedCompletion_VSCodeIssue3365(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.19

-- main.go --
package main

func main() {
	println(strings.TLower)
}

var Lower = ""
`
	find := func(t *testing.T, completions *protocol.CompletionList, name string) protocol.CompletionItem {
		t.Helper()
		if completions == nil || len(completions.Items) == 0 {
			t.Fatalf("no completion items")
		}
		for _, i := range completions.Items {
			if i.Label == name {
				return i
			}
		}
		t.Fatalf("no item with label %q", name)
		return protocol.CompletionItem{}
	}

	for _, supportInsertReplace := range []bool{true, false} {
		t.Run(fmt.Sprintf("insertReplaceSupport=%v", supportInsertReplace), func(t *testing.T) {
			capabilities := fmt.Sprintf(`{ "textDocument": { "completion": { "completionItem": {"insertReplaceSupport":%t, "snippetSupport": false } } } }`, supportInsertReplace)
			runner := WithOptions(
				CapabilitiesJSON([]byte(capabilities)),
				Settings{"importsSource": settings.ImportsSourceGopls},
			)
			runner.Run(t, src, func(t *testing.T, env *Env) {
				env.OpenFile("main.go")
				env.Await(env.DoneWithOpen())
				orig := env.BufferText("main.go")

				// We try to trigger completion at "println(strings.T<>Lower)"
				// and accept the completion candidate that matches the 'accept' label.
				insertModeWant := "println(strings.ToUpperLower)"
				if !supportInsertReplace {
					insertModeWant = "println(strings.ToUpper)"
				}
				testcases := []struct {
					mode   string
					accept string
					want   string
				}{
					{
						mode:   "insert",
						accept: "ToUpper",
						want:   insertModeWant,
					},
					{
						mode:   "insert",
						accept: "ToLower",
						want:   "println(strings.ToLower)", // The suffix 'Lower' is included in the text edit.
					},
					{
						mode:   "replace",
						accept: "ToUpper",
						want:   "println(strings.ToUpper)",
					},
					{
						mode:   "replace",
						accept: "ToLower",
						want:   "println(strings.ToLower)",
					},
				}

				for _, tc := range testcases {
					t.Logf("mode=%q accept=%q", tc.mode, tc.accept)
					env.SetSuggestionInsertReplaceMode(tc.mode == "replace")
					env.SetBufferContent("main.go", orig)
					loc := env.RegexpSearch("main.go", `()Lower\)`)
					completions := env.Completion(loc)
					item := find(t, completions, tc.accept)
					env.AcceptCompletion(loc, item)
					got := env.BufferText("main.go")
					if !strings.Contains(got, tc.want) {
						t.Errorf("unexpected state after completion:\n%v\nwanted %v", got, tc.want)
					}
				}
			})
		})
	}
}
func TestUnimportedCompletionHasPlaceholders60269(t *testing.T) {
	// We can't express this as a marker test because it doesn't support AcceptCompletion.
	const src = `
-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

var _ = b.F

-- b/b.go --
package b

func F0(a, b int, c float64) {}
func F1(int, chan *string) {}
func F2[K, V any](map[K]V, chan V) {} // missing type parameters was issue #60959
func F3[K comparable, V any](map[K]V, chan V) {}
`
	WithOptions(
		WindowsLineEndings(),
		Settings{"ui.completion.usePlaceholders": true,
			"importsSource": settings.ImportsSourceGopls},
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.Await(env.DoneWithOpen())

		// The table lists the expected completions of b.F as they appear in Items.
		const common = "package a\r\n\r\nimport \"example.com/b\"\r\n\r\nvar _ = "
		for i, want := range []string{
			common + "b.F0(${1:a int}, ${2:b int}, ${3:c float64})\r\n",
			common + "b.F1(${1:_ int}, ${2:_ chan *string})\r\n",
			common + "b.F2(${1:_ map[K]V}, ${2:_ chan V})\r\n",
			common + "b.F3(${1:_ map[K]V}, ${2:_ chan V})\r\n",
		} {
			loc := env.RegexpSearch("a/a.go", "b.F()")
			completions := env.Completion(loc)
			if len(completions.Items) == 0 {
				t.Fatalf("no completion items")
			}
			saved := env.BufferText("a/a.go")
			env.AcceptCompletion(loc, completions.Items[i])
			env.Await(env.DoneWithChange())
			got := env.BufferText("a/a.go")
			if diff := cmp.Diff(want, got); diff != "" {
				t.Errorf("%d: unimported completion (-want +got):\n%s", i, diff)
			}
			env.SetBufferContent("a/a.go", saved) // restore
		}
	})
}

func TestPackageMemberCompletionAfterSyntaxError(t *testing.T) {
	// This test documents the current broken behavior due to golang/go#58833.
	const src = `
-- go.mod --
module mod.com

go 1.14

-- main.go --
package main

import "math"

func main() {
	math.Sqrt(,0)
	math.Ldex
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("main.go", "Ldex()")
		completions := env.Completion(loc)
		if len(completions.Items) == 0 {
			t.Fatalf("no completion items")
		}
		env.AcceptCompletion(loc, completions.Items[0])
		env.Await(env.DoneWithChange())
		got := env.BufferText("main.go")
		// The completion of math.Ldex after the syntax error on the
		// previous line is not "math.Ldexp" but "math.Ldexmath.Abs".
		// (In VSCode, "Abs" wrongly appears in the completion menu.)
		// This is a consequence of poor error recovery in the parser
		// causing "math.Ldex" to become a BadExpr.
		want := "package main\n\nimport \"math\"\n\nfunc main() {\n\tmath.Sqrt(,0)\n\tmath.Ldexmath.Abs(${1:})\n}\n"
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("unimported completion (-want +got):\n%s", diff)
		}
	})
}

func TestCompleteAllFields(t *testing.T) {
	// This test verifies that completion results always include all struct fields.
	// See golang/go#53992.

	const src = `
-- go.mod --
module mod.com

go 1.18

-- p/p.go --
package p

import (
	"fmt"

	. "net/http"
	. "runtime"
	. "go/types"
	. "go/parser"
	. "go/ast"
)

type S struct {
	a, b, c, d, e, f, g, h, i, j, k, l, m int
	n, o, p, q, r, s, t, u, v, w, x, y, z int
}

func _() {
	var s S
	fmt.Println(s.)
}
`

	WithOptions(Settings{
		"completionBudget": "1ns", // must be non-zero as 0 => infinity
	}).Run(t, src, func(t *testing.T, env *Env) {
		wantFields := make(map[string]bool)
		for c := 'a'; c <= 'z'; c++ {
			wantFields[string(c)] = true
		}

		env.OpenFile("p/p.go")
		// Make an arbitrary edit to ensure we're not hitting the cache.
		env.EditBuffer("p/p.go", fake.NewEdit(0, 0, 0, 0, fmt.Sprintf("// current time: %v\n", time.Now())))
		loc := env.RegexpSearch("p/p.go", `s\.()`)
		completions := env.Completion(loc)
		gotFields := make(map[string]bool)
		for _, item := range completions.Items {
			if item.Kind == protocol.FieldCompletion {
				gotFields[item.Label] = true
			}
		}

		if diff := cmp.Diff(wantFields, gotFields); diff != "" {
			t.Errorf("Completion(...) returned mismatching fields (-want +got):\n%s", diff)
		}
	})
}

func TestDefinition(t *testing.T) {
	files := `
-- go.mod --
module mod.com

go 1.18
-- a_test.go --
package foo
`
	tests := []struct {
		line string   // the sole line in the buffer after the package statement
		pat  string   // the pattern to search for
		want []string // expected completions
	}{
		{"func T", "T", []string{"TestXxx(t *testing.T)", "TestMain(m *testing.M)"}},
		{"func T()", "T", []string{"TestMain", "Test"}},
		{"func TestM", "TestM", []string{"TestMain(m *testing.M)", "TestM(t *testing.T)"}},
		{"func TestM()", "TestM", []string{"TestMain"}},
		{"func TestMi", "TestMi", []string{"TestMi(t *testing.T)"}},
		{"func TestMi()", "TestMi", nil},
		{"func TestG", "TestG", []string{"TestG(t *testing.T)"}},
		{"func TestG(", "TestG", nil},
		{"func Ben", "B", []string{"BenchmarkXxx(b *testing.B)"}},
		{"func Ben(", "Ben", []string{"Benchmark"}},
		{"func BenchmarkFoo", "BenchmarkFoo", []string{"BenchmarkFoo(b *testing.B)"}},
		{"func BenchmarkFoo(", "BenchmarkFoo", nil},
		{"func Fuz", "F", []string{"FuzzXxx(f *testing.F)"}},
		{"func Fuz(", "Fuz", []string{"Fuzz"}},
		{"func Testx", "Testx", nil},
		{"func TestMe(t *testing.T)", "TestMe", nil},
		{"func Te(t *testing.T)", "Te", []string{"TestMain", "Test"}},
	}
	fname := "a_test.go"
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile(fname)
		env.Await(env.DoneWithOpen())
		for _, test := range tests {
			env.SetBufferContent(fname, "package foo\n"+test.line)
			loc := env.RegexpSearch(fname, test.pat)
			loc.Range.Start.Character += uint32(protocol.UTF16Len([]byte(test.pat)))
			completions := env.Completion(loc)
			if diff := compareCompletionLabels(test.want, completions.Items); diff != "" {
				t.Error(diff)
			}
		}
	})
}

// Test that completing a definition replaces source text when applied, golang/go#56852.
func TestDefinitionReplaceRange(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.17
`

	tests := []struct {
		name          string
		before, after string
	}{
		{
			name: "func TestMa",
			before: `
package foo_test

func TestMa
`,
			after: `
package foo_test

func TestMain(m *testing.M)
`,
		},
		{
			name: "func TestSome",
			before: `
package foo_test

func TestSome
`,
			after: `
package foo_test

func TestSome(t *testing.T)
`,
		},
		{
			name: "func Bench",
			before: `
package foo_test

func Bench
`,
			// Note: Snippet with escaped }.
			after: `
package foo_test

func Benchmark${1:Xxx}(b *testing.B) {
	$0
\}
`,
		},
	}

	Run(t, mod, func(t *testing.T, env *Env) {
		env.CreateBuffer("foo_test.go", "")

		for _, tst := range tests {
			tst.before = strings.Trim(tst.before, "\n")
			tst.after = strings.Trim(tst.after, "\n")
			env.SetBufferContent("foo_test.go", tst.before)

			loc := env.RegexpSearch("foo_test.go", tst.name)
			loc.Range.Start.Character = uint32(protocol.UTF16Len([]byte(tst.name)))
			completions := env.Completion(loc)
			if len(completions.Items) == 0 {
				t.Fatalf("no completion items")
			}

			env.AcceptCompletion(loc, completions.Items[0])
			env.Await(env.DoneWithChange())
			if buf := env.BufferText("foo_test.go"); buf != tst.after {
				t.Errorf("%s:incorrect completion: got %q, want %q", tst.name, buf, tst.after)
			}
		}
	})
}

func TestGoWorkCompletion(t *testing.T) {
	const files = `
-- go.work --
go 1.18

use ./a
use ./a/ba
use ./a/b/
use ./dir/foo
use ./dir/foobar/
use ./missing/
-- a/go.mod --
-- go.mod --
-- a/bar/go.mod --
-- a/b/c/d/e/f/go.mod --
-- dir/bar --
-- dir/foobar/go.mod --
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")

		tests := []struct {
			re   string
			want []string
		}{
			{`use ()\.`, []string{".", "./a", "./a/bar", "./dir/foobar"}},
			{`use \.()`, []string{"", "/a", "/a/bar", "/dir/foobar"}},
			{`use \./()`, []string{"a", "a/bar", "dir/foobar"}},
			{`use ./a()`, []string{"", "/b/c/d/e/f", "/bar"}},
			{`use ./a/b()`, []string{"/c/d/e/f", "ar"}},
			{`use ./a/b/()`, []string{`c/d/e/f`}},
			{`use ./a/ba()`, []string{"r"}},
			{`use ./dir/foo()`, []string{"bar"}},
			{`use ./dir/foobar/()`, []string{}},
			{`use ./missing/()`, []string{}},
		}
		for _, tt := range tests {
			completions := env.Completion(env.RegexpSearch("go.work", tt.re))
			diff := compareCompletionLabels(tt.want, completions.Items)
			if diff != "" {
				t.Errorf("%s: %s", tt.re, diff)
			}
		}
	})
}

const reverseInferenceSrcPrelude = `
-- go.mod --
module mod.com

go 1.18
-- a.go --
package a

type InterfaceA interface {
	implA()
}

type InterfaceB interface {
	implB()
}


type TypeA struct{}

func (TypeA) implA() {}

type TypeX string

func (TypeX) implB() {}

type TypeB struct{}

func (TypeB) implB() {}

type TypeC struct{} // should have no impact

type Wrap[T any] struct {
	inner *T
}

func NewWrap[T any](x T) Wrap[T] {
	return Wrap[T]{inner: &x}
}

func DoubleWrap[T any, U any](t T, u U) (Wrap[T], Wrap[U]) {
	return Wrap[T]{inner: &t}, Wrap[U]{inner: &u}
}

func IntWrap[T int32 | int64](x T) Wrap[T] {
	return Wrap[T]{inner: &x}
}

var ia InterfaceA
var ib InterfaceB

var avar TypeA
var bvar TypeB

var i int
var i32 int32
var i64 int64
`

func TestReverseInferCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var _ Wrap[int64] = IntWrap()
	}
	`
	Run(t, src, func(t *testing.T, env *Env) {
		compl := env.RegexpSearch("a.go", `IntWrap\(()\)`)

		env.OpenFile("a.go")
		result := env.Completion(compl)

		wantLabel := []string{"i64", "i", "i32", "int64()"}

		// only check the prefix due to formatting differences with escaped characters
		wantText := []string{"i64", "int64(i", "int64(i32", "int64("}

		for i, item := range result.Items[:len(wantLabel)] {
			if diff := cmp.Diff(wantLabel[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected label mismatch (-want +got):\n%s", diff)
			}

			if insertText, ok := item.TextEdit.Value.(protocol.InsertReplaceEdit); ok {
				if diff := cmp.Diff(wantText[i], insertText.NewText[:len(wantText[i])]); diff != "" {
					t.Errorf("Completion: unexpected insertText mismatch (checks prefix only) (-want +got):\n%s", diff)
				}
			}
		}
	})
}

func TestInterfaceReverseInferCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var wa Wrap[InterfaceA]
		var wb Wrap[InterfaceB]
		wb = NewWrap() // wb is of type Wrap[InterfaceB]
	}
	`

	Run(t, src, func(t *testing.T, env *Env) {
		compl := env.RegexpSearch("a.go", `NewWrap\(()\)`)

		env.OpenFile("a.go")
		result := env.Completion(compl)

		wantLabel := []string{"ib", "bvar", "wb.inner", "TypeB{}", "TypeX()", "nil"}

		// only check the prefix due to formatting differences with escaped characters
		wantText := []string{"ib", "InterfaceB(", "*wb.inner", "InterfaceB(", "InterfaceB(", "nil"}

		for i, item := range result.Items[:len(wantLabel)] {
			if diff := cmp.Diff(wantLabel[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected label mismatch (-want +got):\n%s", diff)
			}

			if insertText, ok := item.TextEdit.Value.(protocol.InsertReplaceEdit); ok {
				if diff := cmp.Diff(wantText[i], insertText.NewText[:len(wantText[i])]); diff != "" {
					t.Errorf("Completion: unexpected insertText mismatch (checks prefix only) (-want +got):\n%s", diff)
				}
			}
		}
	})
}

func TestInvalidReverseInferenceDefaultsToConstraintCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var wa Wrap[InterfaceA]
		// This is ambiguous, so default to the constraint rather the inference.
		wa = IntWrap()
	}
	`
	Run(t, src, func(t *testing.T, env *Env) {
		compl := env.RegexpSearch("a.go", `IntWrap\(()\)`)

		env.OpenFile("a.go")
		result := env.Completion(compl)

		wantLabel := []string{"i32", "i64", "nil"}

		for i, item := range result.Items[:len(wantLabel)] {
			if diff := cmp.Diff(wantLabel[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected label mismatch (-want +got):\n%s", diff)
			}
		}
	})
}

func TestInterfaceReverseInferTypeParamCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var wa Wrap[InterfaceA]
		var wb Wrap[InterfaceB]
		wb = NewWrap[]()
	}
	`

	Run(t, src, func(t *testing.T, env *Env) {
		compl := env.RegexpSearch("a.go", `NewWrap\[()\]\(\)`)

		env.OpenFile("a.go")
		result := env.Completion(compl)
		want := []string{"InterfaceB", "TypeB", "TypeX", "InterfaceA", "TypeA"}
		for i, item := range result.Items[:len(want)] {
			if diff := cmp.Diff(want[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected mismatch (-want +got):\n%s", diff)
			}
		}
	})
}

func TestInvalidReverseInferenceTypeParamDefaultsToConstraintCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var wa Wrap[InterfaceA]
		// This is ambiguous, so default to the constraint rather the inference.
		wb = IntWrap[]()
	}
	`

	Run(t, src, func(t *testing.T, env *Env) {
		compl := env.RegexpSearch("a.go", `IntWrap\[()\]\(\)`)

		env.OpenFile("a.go")
		result := env.Completion(compl)
		want := []string{"int32", "int64"}
		for i, item := range result.Items[:len(want)] {
			if diff := cmp.Diff(want[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected mismatch (-want +got):\n%s", diff)
			}
		}
	})
}

func TestReverseInferDoubleTypeParamCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func main() {
		var wa Wrap[InterfaceA]
		var wb Wrap[InterfaceB]

		wa, wb = DoubleWrap[]()
		// _ is necessary to trick the parser into an index list expression
		wa, wb = DoubleWrap[InterfaceA, _]()
	}
	`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		compl := env.RegexpSearch("a.go", `DoubleWrap\[()\]\(\)`)
		result := env.Completion(compl)

		wantLabel := []string{"InterfaceA", "TypeA", "InterfaceB", "TypeB", "TypeC"}

		for i, item := range result.Items[:len(wantLabel)] {
			if diff := cmp.Diff(wantLabel[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected label mismatch (-want +got):\n%s", diff)
			}
		}

		compl = env.RegexpSearch("a.go", `DoubleWrap\[InterfaceA, ()_\]\(\)`)
		result = env.Completion(compl)

		wantLabel = []string{"InterfaceB", "TypeB", "TypeX", "InterfaceA", "TypeA"}

		for i, item := range result.Items[:len(wantLabel)] {
			if diff := cmp.Diff(wantLabel[i], item.Label); diff != "" {
				t.Errorf("Completion: unexpected label mismatch (-want +got):\n%s", diff)
			}
		}
	})
}

func TestDoubleParamReturnCompletion(t *testing.T) {
	src := reverseInferenceSrcPrelude + `
	func concrete() (Wrap[InterfaceA], Wrap[InterfaceB]) {
		return DoubleWrap[]()
	}

	func concrete2() (Wrap[InterfaceA], Wrap[InterfaceB]) {
		return DoubleWrap[InterfaceA, _]()
	}
	`

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		tests := map[string][]string{
			`DoubleWrap\[()\]\(\)`:               {"InterfaceA", "TypeA", "InterfaceB", "TypeB", "TypeC"},
			`DoubleWrap\[InterfaceA, ()\_\]\(\)`: {"InterfaceB", "TypeB", "TypeX", "InterfaceA", "TypeA"},
		}

		for re, wantLabels := range tests {
			compl := env.RegexpSearch("a.go", re)
			result := env.Completion(compl)
			if len(result.Items) < len(wantLabels) {
				t.Fatalf("Completion(%q) returned mismatching labels: got %v, want at least labels %v", re, result.Items, wantLabels)
			}
			for i, item := range result.Items[:len(wantLabels)] {
				if diff := cmp.Diff(wantLabels[i], item.Label); diff != "" {
					t.Errorf("Completion(%q): unexpected label mismatch (-want +got):\n%s", re, diff)
				}
			}
		}
	})
}

func TestBuiltinCompletion(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- a.go --
package a

func _() {
	// here
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		result := env.Completion(env.RegexpSearch("a.go", `()\/\/ here`))
		builtins := []string{
			"any", "append", "bool", "byte", "cap", "close",
			"comparable", "complex", "complex128", "complex64", "copy", "delete",
			"error", "false", "float32", "float64", "imag", "int", "int16", "int32",
			"int64", "int8", "len", "make", "new", "panic", "print", "println", "real",
			"recover", "rune", "string", "true", "uint", "uint16", "uint32", "uint64",
			"uint8", "uintptr", "nil",
		}
		if testenv.Go1Point() >= 21 {
			builtins = append(builtins, "clear", "max", "min")
		}
		sort.Strings(builtins)
		var got []string

		for _, item := range result.Items {
			// TODO(rfindley): for flexibility, ignore zero while it is being
			// implemented. Remove this if/when zero lands.
			if item.Label != "zero" {
				got = append(got, item.Label)
			}
		}
		sort.Strings(got)

		if diff := cmp.Diff(builtins, got); diff != "" {
			t.Errorf("Completion: unexpected mismatch (-want +got):\n%s", diff)
		}
	})
}

func TestOverlayCompletion(t *testing.T) {
	const files = `
-- go.mod --
module foo.test

go 1.18

-- foo/foo.go --
package foo

type Foo struct{}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.CreateBuffer("nodisk/nodisk.go", `
package nodisk

import (
	"foo.test/foo"
)

func _() {
	foo.Foo()
}
`)
		list := env.Completion(env.RegexpSearch("nodisk/nodisk.go", "foo.()Foo"))
		want := []string{"Foo"}
		var got []string
		for _, item := range list.Items {
			got = append(got, item.Label)
		}
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("Completion: unexpected mismatch (-want +got):\n%s", diff)
		}
	})
}

// Fix for golang/go#60062: unimported completion included "golang.org/toolchain" results.
// and check that functions (from the standard library) have snippets
func TestToolchainCompletions(t *testing.T) {
	const files = `
-- go.mod --
module foo.test/foo

go 1.21

-- foo.go --
package foo

func _() {
	os.Open
}

func _() {
	strings
}
`

	const proxy = `
-- golang.org/toolchain@v0.0.1-go1.21.1.linux-amd64/go.mod --
module golang.org/toolchain
-- golang.org/toolchain@v0.0.1-go1.21.1.linux-amd64/src/os/os.go --
package os

func Open() {}
-- golang.org/toolchain@v0.0.1-go1.21.1.linux-amd64/src/strings/strings.go --
package strings

func Join() {}
`

	WithOptions(
		ProxyFiles(proxy),
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.RunGoCommand("mod", "download", "golang.org/toolchain@v0.0.1-go1.21.1.linux-amd64")
		env.OpenFile("foo.go")

		for _, pattern := range []string{"os.Open()", "string()"} {
			loc := env.RegexpSearch("foo.go", pattern)
			res := env.Completion(loc)
			for _, item := range res.Items {
				if strings.Contains(item.Detail, "golang.org/toolchain") {
					t.Errorf("Completion(...) returned toolchain item %#v", item)
				}
				if strings.HasPrefix(item.Detail, "func") {
					// check that there are snippets
					x, ok := item.TextEdit.Value.(protocol.InsertReplaceEdit)
					if !ok {
						t.Errorf("item.TextEdit.Value unexpected type %T", item.TextEdit.Value)
					}
					if !strings.Contains(x.NewText, "${1") {
						t.Errorf("expected snippet in %q", x.NewText)
					}
				}
			}
		}
	})
}

// when completing using the module cache, prefer things mentioned
// in the go.mod file.
func TestIssue61208(t *testing.T) {

	const cache = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.22
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.org@v1.2.3/go.mod --
module random.org

go 1.22
-- random.org@v1.2.3/blah/blah.go --
package blah

const Name = "Hello"
`
	const files = `
-- go.mod --
module mod.com
go 1.22
require random.org v1.2.3
-- main.go --
package main
var _ = blah.
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)
	mx := fake.UnpackTxt(cache)
	for k, v := range mx {
		fname := filepath.Join(modcache, k)
		dir := filepath.Dir(fname)
		os.MkdirAll(dir, 0777) // ignore error
		if err := os.WriteFile(fname, v, 0644); err != nil {
			t.Fatal(err)
		}
	}

	WithOptions(
		EnvVars{"GOMODCACHE": modcache},
		WriteGoSum("."),
		Settings{"importsSource": settings.ImportsSourceGopls},
		NoLogsOnError(),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("main.go", "blah.()")
		completions := env.Completion(loc)
		if len(completions.Items) != 1 {
			t.Errorf("got %d, expected 1", len(completions.Items))
			for _, x := range completions.Items {
				t.Logf("%#v", x.AdditionalTextEdits[0].NewText)
			}
		}
		if got := completions.Items[0].AdditionalTextEdits[0].NewText; !strings.Contains(got, `"random.org`) {
			t.Errorf("got %q, expected a `random.org`", got)
		}
	})
}

// show that the efficacy counters get exercised. Fortunately a small program
// exercises them all
func TestCounters(t *testing.T) {
	const files = `
-- go.mod --
module foo
go 1.21
-- x.go --
package foo

func main() {
}

`
	WithOptions(
		Modes(Default),
	).Run(t, files, func(t *testing.T, env *Env) {
		cts := func() map[*counter.Counter]uint64 {
			ans := make(map[*counter.Counter]uint64)
			for _, c := range server.CompletionCounters {
				ans[c], _ = countertest.ReadCounter(c)
			}
			return ans
		}
		before := cts()
		env.OpenFile("x.go")
		env.Await(env.DoneWithOpen())
		saved := env.BufferText("x.go")
		lines := strings.Split(saved, "\n")
		// make sure the unused counter is exercised
		loc := env.RegexpSearch("x.go", "main")
		loc.Range.End = loc.Range.Start
		env.Completion(loc)                       // ignore the proposed completions
		env.RegexpReplace("x.go", "main", "Main") // completions are unused
		env.SetBufferContent("x.go", saved)       // restore x.go
		// used:no

		// all the action is after 4 characters on line 2 (counting from 0)
		for i := 2; i < len(lines); i++ {
			l := lines[i]
			loc.Range.Start.Line = uint32(i)
			for j := 4; j < len(l); j++ {
				loc.Range.Start.Character = uint32(j)
				loc.Range.End = loc.Range.Start
				res := env.Completion(loc)
				if len(res.Items) > 0 {
					r := res.Items[0]
					env.AcceptCompletion(loc, r)
					env.SetBufferContent("x.go", saved)
				}
			}
		}
		after := cts()
		for c := range after {
			if after[c] <= before[c] {
				t.Errorf("%s did not increase", c.Name())
			}
		}
	})
}

// find import foo "bar" for foo.xxx
func TestImportAlias(t *testing.T) {
	testenv.NeedsGoCommand1Point(t, 24) // we will find math/rand/v2
	const files = `
-- a.go --
package x
var _ = xrand.
-- b.go --
package x

import xrand "math/rand"

var _ = xrand.Int()

-- go.mod --
module foo.com

go 1.24.2
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("a.go", "xrand.()")
		compls := env.Completion(loc)
		if len(compls.Items) == 0 {
			t.Fatal("no completions")
		}
		one := compls.Items[0].AdditionalTextEdits[0].NewText
		if one != "\nimport xrand \"math/rand\"\n" {
			t.Errorf("wrong import %q", one)
		}
	})
}

func TestModIndexDirEmpty(t *testing.T) {
	// Test for issue #75505. Do not run this test in parallel.
	// Test that if modindex.IndexDir is empty, we still get stdlib completions
	// but not unimported completions from modules.

	// Save/restore IndexDir, and set it to empty string.
	// This simulates having no module cache.
	old := modindex.IndexDir
	modindex.IndexDir = ""
	defer func() { modindex.IndexDir = old }()
	// for the paranoid, with modindex.IndexDir = old here, the test fails

	const mod = `
-- go.mod --
module mod.com
go 1.22
require example.com v1.2.3
-- main.go --
package main
func main() {
	_ = fmt.P
	_ = blah.N
}
-- main2.go --
package main
import "example.com/blah"
func _() {
	_ = blah.Hello
}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy), // providing example.com through GOPROXY to the go command
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, mod, func(t *testing.T, env *Env) {
		// We need example.com in the module cache, but not
		// otherwise available to the completion logic.
		env.RemoveWorkspaceFile("main2.go")
		env.RunGoCommand("mod", "tidy")
		env.Await(env.DoneWithChangeWatchedFiles())

		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())

		// 1. Check stdlib completion (should work)
		loc := env.RegexpSearch("main.go", "fmt.P()")
		completions := env.Completion(loc)
		if len(completions.Items) == 0 {
			t.Errorf("stdlib completion failed to find fmt.Print...")
		}

		// 2. Check unimported completion (should fail)
		// We look for "blah.H" which is from example.com
		loc = env.RegexpSearch("main.go", "blah.N()")
		completions = env.Completion(loc)

		// We expect NO unimported completions for blah.Name because modindex is disabled.
		for _, item := range completions.Items {
			// We shouldn't get candidate from example.com/blah.
			if strings.Contains(item.Detail, "example.com/blah") {
				t.Errorf("unexpected unimported completion for blah with empty IndexDir: %v", item)
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/completion/fixedbugs_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestPackageCompletionCrash_Issue68169(t *testing.T) {
	// This test reproduces the scenario of golang/go#68169, a crash in
	// completion.Selection.Suffix.
	//
	// The file content here is extracted from the issue.
	const files = `
-- go.mod --
module example.com

go 1.18
-- playdos/play.go --
package   // comment (to preserve spaces)
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("playdos/play.go")
		// Previously, this call would crash gopls as it was incorrectly computing
		// the surrounding completion suffix.
		completions := env.Completion(env.RegexpSearch("playdos/play.go", "package  ()"))
		if len(completions.Items) == 0 {
			t.Fatal("Completion() returned empty results")
		}
		// Sanity check: we should get package clause completion.
		if got, want := completions.Items[0].Label, "package playdos"; got != want {
			t.Errorf("Completion()[0].Label == %s, want %s", got, want)
		}
	})
}

func TestFixInitStatementCrash_Issue72026(t *testing.T) {
	// This test checks that we don't crash when the if condition overflows the
	// file (as is possible with a malformed struct type).

	const files = `
-- go.mod --
module example.com

go 1.18
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.CreateBuffer("p.go", "package p\nfunc _() {\n\tfor i := struct")
		env.AfterChange()
	})
}


================================================
FILE: gopls/internal/test/integration/completion/postfix_snippet_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package completion

import (
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestPostfixSnippetCompletion(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
`

	cases := []struct {
		name              string
		before, after     string
		allowMultipleItem bool
	}{
		{
			name: "sort",
			before: `
package foo

func _() {
	var foo []int
	foo.sort
}
`,
			after: `
package foo

import "sort"

func _() {
	var foo []int
	sort.Slice(foo, func(i, j int) bool {
	$0
})
}
`,
		},
		{
			name: "sort_renamed_sort_package",
			before: `
package foo

import blahsort "sort"

var j int

func _() {
	var foo []int
	foo.sort
}
`,
			after: `
package foo

import blahsort "sort"

var j int

func _() {
	var foo []int
	blahsort.Slice(foo, func(i, j2 int) bool {
	$0
})
}
`,
		},
		{
			name: "last",
			before: `
package foo

func _() {
	var s struct { i []int }
	s.i.last
}
`,
			after: `
package foo

func _() {
	var s struct { i []int }
	s.i[len(s.i)-1]
}
`,
		},
		{
			name: "reverse",
			before: `
package foo

func _() {
	var foo []int
	foo.reverse
}
`,
			after: `
package foo

import "slices"

func _() {
	var foo []int
	slices.Reverse(foo)
}
`,
		},
		{
			name: "slice_range",
			before: `
package foo

func _() {
	type myThing struct{}
	var foo []myThing
	foo.range
}
`,
			after: `
package foo

func _() {
	type myThing struct{}
	var foo []myThing
	for ${1:}, ${2:} := range foo {
	$0
}
}
`,
		},
		{
			name: "append_stmt",
			before: `
package foo

func _() {
	var foo []int
	foo.append
}
`,
			after: `
package foo

func _() {
	var foo []int
	foo = append(foo, $0)
}
`,
		},
		{
			name: "append_expr",
			before: `
package foo

func _() {
	var foo []int
	var _ []int = foo.append
}
`,
			after: `
package foo

func _() {
	var foo []int
	var _ []int = append(foo, $0)
}
`,
		},
		{
			name: "slice_copy",
			before: `
package foo

func _() {
	var foo []int
	foo.copy
}
`,
			after: `
package foo

func _() {
	var foo []int
	fooCopy := make([]int, len(foo))
copy(fooCopy, foo)

}
`,
		},
		{
			name: "map_range",
			before: `
package foo

func _() {
	var foo map[string]int
	foo.range
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	for ${1:}, ${2:} := range foo {
	$0
}
}
`,
		},
		{
			name: "map_clear",
			before: `
package foo

func _() {
	var foo map[string]int
	foo.clear
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	for k := range foo {
	delete(foo, k)
}

}
`,
		},
		{
			name: "map_keys",
			before: `
package foo

func _() {
	var foo map[string]int
	foo.keys
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	keys := make([]string, 0, len(foo))
for k := range foo {
	keys = append(keys, k)
}

}
`,
		},
		{
			name: "channel_range",
			before: `
package foo

func _() {
	foo := make(chan int)
	foo.range
}
`,
			after: `
package foo

func _() {
	foo := make(chan int)
	for ${1:} := range foo {
	$0
}
}
`,
		},
		{
			name: "var",
			before: `
package foo

func foo() (int, error) { return 0, nil }

func _() {
	foo().var
}
`,
			after: `
package foo

func foo() (int, error) { return 0, nil }

func _() {
	${1:}, ${2:} := foo()
}
`,
			allowMultipleItem: true,
		},
		{
			name: "var_single_value",
			before: `
package foo

func foo() error { return nil }

func _() {
	foo().var
}
`,
			allowMultipleItem: true,
			after: `
package foo

func foo() error { return nil }

func _() {
	${1:} := foo()
}
`,
		},
		{
			name: "var_same_type",
			before: `
package foo

func foo() (int, int) { return 0, 0 }

func _() {
	foo().var
}
`,
			after: `
package foo

func foo() (int, int) { return 0, 0 }

func _() {
	${1:}, ${2:} := foo()
}
`,
		},
		{
			name: "print_scalar",
			before: `
package foo

func _() {
	var foo int
	foo.print
}
`,
			after: `
package foo

import "fmt"

func _() {
	var foo int
	fmt.Printf("foo: %v\n", foo)
}
`,
		},
		{
			name: "print_multi",
			before: `
package foo

func foo() (int, error) { return 0, nil }

func _() {
	foo().print
}
`,
			after: `
package foo

import "fmt"

func foo() (int, error) { return 0, nil }

func _() {
	fmt.Println(foo())
}
`,
		},
		{
			name: "string split",
			before: `
package foo

func foo() []string {
	x := "test"
	return x.split
}`,
			after: `
package foo

import "strings"

func foo() []string {
	x := "test"
	return strings.Split(x, "$0")
}`,
		},
		{
			name: "string slice join",
			before: `
package foo

func foo() string {
	x := []string{"a", "test"}
	return x.join
}`,
			after: `
package foo

import "strings"

func foo() string {
	x := []string{"a", "test"}
	return strings.Join(x, "$0")
}`,
		},
		{
			name: "if not nil interface",
			before: `
package foo

func _() {
	var foo error
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo error
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "if not nil pointer",
			before: `
package foo

func _() {
	var foo *int
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo *int
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "if not nil slice",
			before: `
package foo

func _() {
	var foo []int
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo []int
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "if not nil map",
			before: `
package foo

func _() {
	var foo map[string]any
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo map[string]any
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "if not nil channel",
			before: `
package foo

func _() {
	var foo chan int
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo chan int
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "if not nil function",
			before: `
package foo

func _() {
	var foo func()
	foo.ifnotnil
}
`,
			after: `
package foo

func _() {
	var foo func()
	if foo != nil {
	$0
}
}
`,
		},
		{
			name: "slice_len",
			before: `
package foo

func _() {
	var foo []int
	foo.len
}
`,
			after: `
package foo

func _() {
	var foo []int
	len(foo)
}
`,
		},
		{
			name: "map_len",
			before: `
package foo

func _() {
	var foo map[string]int
	foo.len
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	len(foo)
}
`,
		},
		{
			name:              "slice_for",
			allowMultipleItem: true,
			before: `
package foo

func _() {
	var foo []int
	foo.for
}
`,
			after: `
package foo

func _() {
	var foo []int
	for ${1:} := range foo {
	$0
}
}
`,
		},
		{
			name:              "map_for",
			allowMultipleItem: true,
			before: `
package foo

func _() {
	var foo map[string]int
	foo.for
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	for ${1:} := range foo {
	$0
}
}
`,
		},
		{
			name:              "chan_for",
			allowMultipleItem: true,
			before: `
package foo

func _() {
	var foo chan int
	foo.for
}
`,
			after: `
package foo

func _() {
	var foo chan int
	for ${1:} := range foo {
	$0
}
}
`,
		},
		{
			name: "slice_forr",
			before: `
package foo

func _() {
	var foo []int
	foo.forr
}
`,
			after: `
package foo

func _() {
	var foo []int
	for ${1:}, ${2:} := range foo {
	$0
}
}
`,
		},
		{
			name: "slice_forr",
			before: `
package foo

func _() {
	var foo []int
	foo.forr
}
`,
			after: `
package foo

func _() {
	var foo []int
	for ${1:}, ${2:} := range foo {
	$0
}
}
`,
		},
		{
			name: "map_forr",
			before: `
package foo

func _() {
	var foo map[string]int
	foo.forr
}
`,
			after: `
package foo

func _() {
	var foo map[string]int
	for ${1:}, ${2:} := range foo {
	$0
}
}
`,
		},
	}

	r := WithOptions(
		Settings{
			"experimentalPostfixCompletions": true,
		},
	)
	r.Run(t, mod, func(t *testing.T, env *Env) {
		env.CreateBuffer("foo.go", "")

		for _, c := range cases {
			t.Run(c.name, func(t *testing.T) {
				c.before = strings.Trim(c.before, "\n")
				c.after = strings.Trim(c.after, "\n")

				env.SetBufferContent("foo.go", c.before)

				loc := env.RegexpSearch("foo.go", `()\n\}`)
				completions := env.Completion(loc)
				if len(completions.Items) < 1 {
					t.Fatalf("expected at least one completion, got %v", completions.Items)
				}
				if !c.allowMultipleItem && len(completions.Items) > 1 {
					t.Fatalf("expected one completion, got %v", completions.Items)
				}

				env.AcceptCompletion(loc, completions.Items[0])

				if buf := env.BufferText("foo.go"); buf != c.after {
					t.Errorf("\nGOT:\n%s\nEXPECTED:\n%s", buf, c.after)
				}
			})
		}
	})
}


================================================
FILE: gopls/internal/test/integration/debug/debug_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package debug

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"os"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	os.Exit(Main(m))
}

func TestBugNotification(t *testing.T) {
	// Verify that a properly configured session gets notified of a bug on the
	// server.
	WithOptions(
		Modes(Default), // must be in-process to receive the bug report below
		Settings{"showBugReports": true},
	).Run(t, "", func(t *testing.T, env *Env) {
		const desc = "got a bug"
		bug.Report(desc)
		env.Await(ShownMessage(desc))
	})
}

// TestStartDebugging executes a gopls.start_debugging command to
// start the internal web server.
func TestStartDebugging(t *testing.T) {
	WithOptions(
		Modes(Default), // doesn't work in Forwarded mode
	).Run(t, "", func(t *testing.T, env *Env) {
		// Start a debugging server.
		res, err := startDebugging(env.Ctx, env.Editor.Server, &command.DebuggingArgs{
			Addr: "", // any free port
		})
		if err != nil {
			t.Fatalf("startDebugging: %v", err)
		}

		// Assert that the server requested that the
		// client show the debug page in a browser.
		debugURL := res.URLs[0]
		env.Await(ShownDocument(debugURL))

		// Send a request to the debug server and ensure it responds.
		resp, err := http.Get(debugURL)
		if err != nil {
			t.Fatal(err)
		}
		defer resp.Body.Close()
		data, err := io.ReadAll(resp.Body)
		if err != nil {
			t.Fatalf("reading HTTP response body: %v", err)
		}
		const want = "<title>Gopls"
		if !strings.Contains(string(data), want) {
			t.Errorf("GET %s response does not contain %q: <<%s>>", debugURL, want, data)
		}
	})
}

// startDebugging starts a debugging server.
// TODO(adonovan): move into command package?
func startDebugging(ctx context.Context, server protocol.Server, args *command.DebuggingArgs) (*command.DebuggingResult, error) {
	rawArgs, err := command.MarshalArgs(args)
	if err != nil {
		return nil, err
	}
	res0, err := server.ExecuteCommand(ctx, &protocol.ExecuteCommandParams{
		Command:   command.StartDebugging.String(),
		Arguments: rawArgs,
	})
	if err != nil {
		return nil, err
	}
	// res0 is the result of a schemaless (map[string]any) JSON decoding.
	// Re-encode and decode into the correct Go struct type.
	// TODO(adonovan): fix (*serverDispatcher).ExecuteCommand.
	data, err := json.Marshal(res0)
	if err != nil {
		return nil, err
	}
	var res *command.DebuggingResult
	if err := json.Unmarshal(data, &res); err != nil {
		return nil, err
	}
	return res, nil
}


================================================
FILE: gopls/internal/test/integration/diagnostics/analysis_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"fmt"
	"testing"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/internal/testenv"
)

// Test for the timeformat analyzer, following golang/vscode-go#2406.
//
// This test checks that applying the suggested fix from the analyzer resolves
// the diagnostic warning.
func TestTimeFormatAnalyzer(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

import (
	"fmt"
	"time"
)

func main() {
	now := time.Now()
	fmt.Println(now.Format("2006-02-01"))
}`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")

		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "2006-02-01")),
			ReadDiagnostics("main.go", &d),
		)

		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

func TestAnalysisProgressReporting(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18

-- main.go --
package main

func main() {
}`

	tests := []struct {
		setting bool
		want    Expectation
	}{
		{true, CompletedWork(cache.AnalysisProgressTitle, 1, true)},
		{false, Not(CompletedWork(cache.AnalysisProgressTitle, 1, true))},
	}

	for _, test := range tests {
		t.Run(fmt.Sprint(test.setting), func(t *testing.T) {
			WithOptions(
				Settings{
					"reportAnalysisProgressAfter": "0s",
					"analysisProgressReporting":   test.setting,
				},
			).Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("main.go")
				env.AfterChange(test.want)
			})
		})
	}
}

// Test the embed directive analyzer.
//
// There is a fix for missing imports, but it should not trigger for other
// kinds of issues reported by the analayzer, here the variable
// declaration following the embed directive is wrong.
func TestNoSuggestedFixesForEmbedDirectiveDeclaration(t *testing.T) {
	const generated = `
-- go.mod --
module mod.com

go 1.20

-- foo.txt --
FOO

-- main.go --
package main

import _ "embed"

//go:embed foo.txt
var foo, Bar string

func main() {
	_ = foo
}
`
	Run(t, generated, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "//go:embed")),
			ReadDiagnostics("main.go", &d),
		)
		if fixes := env.GetQuickFixes("main.go", d.Diagnostics); len(fixes) != 0 {
			t.Errorf("got quick fixes %v, wanted none", fixes)
		}
	})
}

func TestAnalysisFiltering(t *testing.T) {
	// This test checks that hint level diagnostics are only surfaced for open
	// files.

	const src = `
-- go.mod --
module mod.com

go 1.20

-- a.go --
package p

var X interface{}

-- b.go --
package p

var Y interface{}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(
			Diagnostics(ForFile("a.go"), WithMessage("replaced by any")),
			NoDiagnostics(ForFile("b.go")),
		)
	})
}

func TestModernizationConsistency_Issue75000(t *testing.T) {
	testenv.SkipAfterGoCommand1Point(t, 24)
	testenv.NeedsGoCommand1Point(t, 22) // uses range-over-int

	// This test checks that we don't offer modernization suggestions when the
	// ambient Go version is older than the modernized APIs.
	//
	// The code is from golang/go#75000, where gopls suggested to use
	// `waitgroup.Go` even though the user was on 1.24.

	const src = `
-- main.go --
package main

import (
	"fmt"
	"sync"
)

func doit(i int) {
	fmt.Println("i = ", i)
}

func main() {
	var wg sync.WaitGroup
	for i := range 5 {
		wg.Add(1)
		go func() {
			defer wg.Done()
			doit(i)
		}()
	}

	wg.Wait()
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(NoDiagnostics())
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/builtin_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestIssue44866(t *testing.T) {
	src := `
-- go.mod --
module mod.com

go 1.12
-- a.go --
package a

const (
	c = iota
)
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		loc := env.FirstDefinition(env.RegexpSearch("a.go", "iota"))
		if !strings.HasSuffix(string(loc.URI), "builtin.go") {
			t.Fatalf("jumped to %q, want builtin.go", loc.URI)
		}
		env.AfterChange(NoDiagnostics(ForFile("builtin.go")))
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/diagnostics_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/server"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

// Use mod.com for all go.mod files due to golang/go#35230.
const exampleProgram = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}`

func TestDiagnosticErrorInEditedFile(t *testing.T) {
	// This test is very basic: start with a clean Go program, make an error, and
	// get a diagnostic for that error. However, it also demonstrates how to
	// combine Expectations to await more complex state in the editor.
	RunMultiple{
		{"golist", WithOptions(Modes(Default))},
		{"gopackages", WithOptions(
			Modes(Default),
			FakeGoPackagesDriver(t),
		)},
	}.Run(t, exampleProgram, func(t *testing.T, env *Env) {
		// Deleting the 'n' at the end of Println should generate a single error
		// diagnostic.
		env.OpenFile("main.go")
		env.RegexpReplace("main.go", "Printl(n)", "")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "Printl")),
			// Assert that this test has sent no error logs to the client. This is not
			// strictly necessary for testing this regression, but is included here
			// as an example of using the NoErrorLogs() expectation. Feel free to
			// delete.
			NoErrorLogs(),
		)
	})
}

func TestMissingImportDiagsClearOnFirstFile(t *testing.T) {
	const onlyMod = `
-- go.mod --
module mod.com

go 1.12
`
	WithOptions(
		Settings{
			"pullDiagnostics": true,
		},
	).Run(t, onlyMod, func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", `package main

func _() {
	log.Println()
}
`)
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", "log")))
		env.SaveBuffer("main.go")
		if got := env.Diagnostics("main.go"); len(got) != 0 {
			t.Errorf("got %d diagnostics, want 0", len(got))
		}
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

func TestDiagnosticErrorInNewFile(t *testing.T) {
	const brokenFile = `package main

const Foo = "abc
`
	RunMultiple{
		{"golist", WithOptions(Modes(Default))},
		// Since this test requires loading an overlay,
		// it verifies that the fake go/packages driver honors overlays.
		{"gopackages", WithOptions(
			Modes(Default),
			FakeGoPackagesDriver(t),
		)},
	}.Run(t, brokenFile, func(t *testing.T, env *Env) {
		env.CreateBuffer("broken.go", brokenFile)
		env.AfterChange(Diagnostics(env.AtRegexp("broken.go", "\"abc")))
	})
}

// badPackage contains a duplicate definition of the 'A' const.
const badPackage = `
-- go.mod --
module mod.com

go 1.12
-- a.go --
package consts

const A = 1
-- b.go --
package consts

const A = 2
`

func TestDiagnosticClearingOnEdit(t *testing.T) {
	WithOptions(
		Settings{
			"pullDiagnostics": true,
		},
	).Run(t, badPackage, func(t *testing.T, env *Env) {
		env.OpenFile("b.go")

		for _, f := range []string{"a.go", "b.go"} {
			if got := env.Diagnostics(f); len(got) != 1 {
				t.Errorf("textDocument/diagnostic(%s) returned %d diagnostics, want 1. Got %v", f, len(got), got)
			}
		}
		env.AfterChange(
			Diagnostics(env.AtRegexp("a.go", "A = 1")),
			Diagnostics(env.AtRegexp("b.go", "A = 2")),
		)

		// Fix the error by editing the const name A in b.go to `B`.
		env.RegexpReplace("b.go", "(A) = 2", "B")
		for _, f := range []string{"a.go", "b.go"} {
			if got := env.Diagnostics(f); len(got) != 0 {
				t.Errorf("textDocument/diagnostic(%s) returned %d diagnostics, want 0. Got %v", f, len(got), got)
			}
		}
		env.AfterChange(
			NoDiagnostics(ForFile("a.go")),
			NoDiagnostics(ForFile("b.go")),
		)
	})
}

func TestDiagnosticClearingOnDelete_Issue37049(t *testing.T) {
	Run(t, badPackage, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a.go", "A = 1")),
			Diagnostics(env.AtRegexp("b.go", "A = 2")),
		)
		env.RemoveWorkspaceFile("b.go")

		env.AfterChange(
			NoDiagnostics(ForFile("a.go")),
			NoDiagnostics(ForFile("b.go")),
		)
	})
}

func TestDiagnosticClearingOnClose(t *testing.T) {
	Run(t, badPackage, func(t *testing.T, env *Env) {
		env.CreateBuffer("c.go", `package consts

const A = 3`)
		env.AfterChange(
			Diagnostics(env.AtRegexp("a.go", "A = 1")),
			Diagnostics(env.AtRegexp("b.go", "A = 2")),
			Diagnostics(env.AtRegexp("c.go", "A = 3")),
		)
		env.CloseBuffer("c.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a.go", "A = 1")),
			Diagnostics(env.AtRegexp("b.go", "A = 2")),
			NoDiagnostics(ForFile("c.go")),
		)
	})
}

// Tests golang/go#37978.
func TestIssue37978(t *testing.T) {
	Run(t, exampleProgram, func(t *testing.T, env *Env) {
		// Create a new workspace-level directory and empty file.
		env.CreateBuffer("c/c.go", "")

		// Write the file contents with a missing import.
		env.EditBuffer("c/c.go", protocol.TextEdit{
			NewText: `package c

const A = http.MethodGet
`,
		})
		env.AfterChange(
			Diagnostics(env.AtRegexp("c/c.go", "http.MethodGet")),
		)
		// Save file, which will organize imports, adding the expected import.
		// Expect the diagnostics to clear.
		env.SaveBuffer("c/c.go")
		env.AfterChange(
			NoDiagnostics(ForFile("c/c.go")),
		)
	})
}

// Tests golang/go#38878: good a.go, bad a_test.go, remove a_test.go but its errors remain
// If the file is open in the editor, this is working as intended
// If the file is not open in the editor, the errors go away
const test38878 = `
-- go.mod --
module foo

go 1.12
-- a.go --
package x

// import "fmt"

func f() {}

-- a_test.go --
package x

import "testing"

func TestA(t *testing.T) {
	f(3)
}
`

// Tests golang/go#38878: deleting a test file should clear its errors, and
// not break the workspace.
func TestDeleteTestVariant(t *testing.T) {
	Run(t, test38878, func(t *testing.T, env *Env) {
		env.AfterChange(Diagnostics(env.AtRegexp("a_test.go", `f\((3)\)`)))
		env.RemoveWorkspaceFile("a_test.go")
		env.AfterChange(NoDiagnostics(ForFile("a_test.go")))

		// Make sure the test variant has been removed from the workspace by
		// triggering a metadata load.
		env.OpenFile("a.go")
		env.RegexpReplace("a.go", `// import`, "import")
		env.AfterChange(Diagnostics(env.AtRegexp("a.go", `"fmt"`)))
	})
}

// Tests golang/go#38878: deleting a test file on disk while it's still open
// should not clear its errors.
func TestDeleteTestVariant_DiskOnly(t *testing.T) {
	Run(t, test38878, func(t *testing.T, env *Env) {
		env.OpenFile("a_test.go")
		env.AfterChange(Diagnostics(AtPosition("a_test.go", 5, 3)))
		env.Sandbox.Workdir.RemoveFile(context.Background(), "a_test.go") // ignore error
		env.AfterChange(Diagnostics(AtPosition("a_test.go", 5, 3)))
	})
}

// TestNoMod confirms that gopls continues to work when a user adds a go.mod
// file to their workspace.
func TestNoMod(t *testing.T) {
	const noMod = `
-- main.go --
package main

import "mod.com/bob"

func main() {
	bob.Hello()
}
-- bob/bob.go --
package bob

func Hello() {
	var x int
}
`

	t.Run("manual", func(t *testing.T) {
		Run(t, noMod, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("main.go", `"mod.com/bob"`)),
			)
			env.CreateBuffer("go.mod", `module mod.com

	go 1.12
`)
			env.SaveBuffer("go.mod")
			var d protocol.PublishDiagnosticsParams
			env.AfterChange(
				NoDiagnostics(ForFile("main.go")),
				Diagnostics(env.AtRegexp("bob/bob.go", "x")),
				ReadDiagnostics("bob/bob.go", &d),
			)
			if len(d.Diagnostics) != 1 {
				t.Fatalf("expected 1 diagnostic, got %v", len(d.Diagnostics))
			}
		})
	})
	t.Run("initialized", func(t *testing.T) {
		Run(t, noMod, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("main.go", `"mod.com/bob"`)),
			)
			env.RunGoCommand("mod", "init", "mod.com")
			env.AfterChange(
				NoDiagnostics(ForFile("main.go")),
				Diagnostics(env.AtRegexp("bob/bob.go", "x")),
			)
		})
	})

	t.Run("without workspace module", func(t *testing.T) {
		WithOptions(
			Modes(Default),
		).Run(t, noMod, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("main.go", `"mod.com/bob"`)),
			)
			if _, err := env.Sandbox.RunGoCommand(env.Ctx, "", "mod", []string{"init", "mod.com"}, nil, true); err != nil {
				t.Fatal(err)
			}
			env.AfterChange(
				NoDiagnostics(ForFile("main.go")),
				Diagnostics(env.AtRegexp("bob/bob.go", "x")),
			)
		})
	})
}

// Tests golang/go#38267.
func TestIssue38267(t *testing.T) {
	const testPackage = `
-- go.mod --
module mod.com

go 1.12
-- lib.go --
package lib

func Hello(x string) {
	_ = x
}
-- lib_test.go --
package lib

import "testing"

type testStruct struct{
	name string
}

func TestHello(t *testing.T) {
	testStructs := []*testStruct{
		&testStruct{"hello"},
		&testStruct{"goodbye"},
	}
	for y := range testStructs {
		_ = y
	}
}
`

	Run(t, testPackage, func(t *testing.T, env *Env) {
		env.OpenFile("lib_test.go")
		env.AfterChange(
			Diagnostics(AtPosition("lib_test.go", 10, 2)),
			Diagnostics(AtPosition("lib_test.go", 11, 2)),
		)
		env.OpenFile("lib.go")
		env.RegexpReplace("lib.go", "_ = x", "var y int")
		env.AfterChange(
			Diagnostics(env.AtRegexp("lib.go", "y int")),
			NoDiagnostics(ForFile("lib_test.go")),
		)
	})
}

// Tests golang/go#38328.
func TestPackageChange_Issue38328(t *testing.T) {
	const packageChange = `
-- go.mod --
module fake

go 1.12
-- a.go --
package foo
func main() {}
`
	Run(t, packageChange, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.RegexpReplace("a.go", "foo", "foox")
		env.AfterChange(
			NoDiagnostics(ForFile("a.go")),
		)
	})
}

const testPackageWithRequire = `
-- go.mod --
module mod.com

go 1.12

require foo.test v1.2.3
-- print.go --
package lib

import (
	"fmt"

	"foo.test/bar"
)

func PrintAnswer() {
	fmt.Printf("answer: %s", bar.Answer)
}
`

const testPackageWithRequireProxy = `
-- foo.test@v1.2.3/go.mod --
module foo.test

go 1.12
-- foo.test@v1.2.3/bar/const.go --
package bar

const Answer = 42
`

func TestResolveDiagnosticWithDownload(t *testing.T) {
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(testPackageWithRequireProxy),
	).Run(t, testPackageWithRequire, func(t *testing.T, env *Env) {
		env.OpenFile("print.go")
		// Check that gopackages correctly loaded this dependency. We should get a
		// diagnostic for the wrong formatting type.
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("print.go", "%s"),
				WithMessage("wrong type int"),
			),
		)
	})
}

func TestMissingDependency(t *testing.T) {
	Run(t, testPackageWithRequire, func(t *testing.T, env *Env) {
		env.OpenFile("print.go")
		env.Await(
			// Log messages are asynchronous to other events on the LSP stream, so we
			// can't use OnceMet or AfterChange here.
			LogMatching(protocol.Error, "initial workspace load failed", 1, false),
		)
	})
}

// Tests golang/go#36951.
func TestAdHocPackages_Issue36951(t *testing.T) {
	const adHoc = `
-- b/b.go --
package b

func Hello() {
	var x int
}
`
	Run(t, adHoc, func(t *testing.T, env *Env) {
		env.OpenFile("b/b.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("b/b.go", "x")),
		)
	})
}

// Tests golang/go#37984: GOPATH should be read from the go command.
func TestNoGOPATH_Issue37984(t *testing.T) {
	const files = `
-- main.go --
package main

func _() {
	fmt.Println("Hello World")
}
`
	WithOptions(
		EnvVars{
			"GOPATH":      "",
			"GO111MODULE": "off",
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", "fmt")))
		env.SaveBuffer("main.go")
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

// Tests golang/go#38669.
func TestEqualInEnv_Issue38669(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

var _ = x.X
-- x/x.go --
package x

var X = 0
`
	WithOptions(
		EnvVars{"GOFLAGS": "-tags=foo"},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OrganizeImports("main.go")
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

// Tests golang/go#38467.
func TestNoSuggestedFixesForGeneratedFiles_Issue38467(t *testing.T) {
	// This test ensures that gopls' CodeAction handler suppresses
	// diagnostics in generated code. Beware that many analyzers
	// themselves suppress diagnostics in generated files, in
	// particular the low-status "simplifiers" (modernize,
	// simplify{range,slice,compositelit}), so we use the hostport
	// analyzer here.
	const generated = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
// Code generated by generator.go. DO NOT EDIT.

package main

import ("fmt"; "net")

func _() {
	addr := fmt.Sprintf("%s:%d", "localhost", 12345)
	net.Dial("tcp", addr)
}
`
	Run(t, generated, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(AtPosition("main.go", 7, 21)),
			ReadDiagnostics("main.go", &d),
		)
		if fixes := env.GetQuickFixes("main.go", d.Diagnostics); len(fixes) != 0 {
			t.Errorf("got quick fixes %v, wanted none", fixes)
		}
	})
}

// Expect a module/GOPATH error if there is an error in the file at startup.
// Tests golang/go#37279.
func TestBrokenWorkspace_OutsideModule(t *testing.T) {
	const noModule = `
-- a.go --
package foo

import "mod.com/hello"

func f() {
	hello.Goodbye()
}
`
	Run(t, noModule, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(
			// AdHoc views are not critical errors, but their missing import
			// diagnostics should specifically mention GOROOT or GOPATH (and not
			// modules).
			NoOutstandingWork(IgnoreTelemetryPromptWork),
			Diagnostics(
				env.AtRegexp("a.go", `"mod.com`),
				WithMessage("in GOROOT"),
			),
		)
		// Deleting the import dismisses the warning.
		env.RegexpReplace("a.go", `import "mod.com/hello"`, "")
		env.AfterChange(
			NoOutstandingWork(IgnoreTelemetryPromptWork),
		)
	})
}

func TestNonGoFolder(t *testing.T) {
	const files = `
-- hello.txt --
hi mom
`
	for _, go111module := range []string{"on", "off", ""} {
		t.Run(fmt.Sprintf("GO111MODULE_%v", go111module), func(t *testing.T) {
			WithOptions(
				EnvVars{"GO111MODULE": go111module},
			).Run(t, files, func(t *testing.T, env *Env) {
				env.OnceMet(
					InitialWorkspaceLoad,
					NoOutstandingWork(IgnoreTelemetryPromptWork),
				)
			})
		})
	}
}

// Tests the repro case from golang/go#38602. Diagnostics are now handled properly,
// which blocks type checking.
func TestConflictingMainPackageErrors(t *testing.T) {
	const collision = `
-- x/x.go --
package x

import "x/hello"

func Hello() {
	hello.HiThere()
}
-- x/main.go --
package main

func main() {
	fmt.Println("")
}
`
	WithOptions(
		InGOPATH(),
		EnvVars{"GO111MODULE": "off"},
	).Run(t, collision, func(t *testing.T, env *Env) {
		env.OpenFile("x/x.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("x/x.go", `^`), WithMessage("found packages main (main.go) and x (x.go)")),
			Diagnostics(env.AtRegexp("x/main.go", `^`), WithMessage("found packages main (main.go) and x (x.go)")),
		)

		// We don't recover cleanly from the errors without good overlay support.
		if testenv.Go1Point() >= 16 {
			env.RegexpReplace("x/x.go", `package x`, `package main`)
			env.AfterChange(
				Diagnostics(env.AtRegexp("x/main.go", `fmt`)),
			)
		}
	})
}

const ardanLabsProxy = `
-- github.com/ardanlabs/conf@v1.2.3/go.mod --
module github.com/ardanlabs/conf

go 1.12
-- github.com/ardanlabs/conf@v1.2.3/conf.go --
package conf

var ErrHelpWanted error
`

// Test for golang/go#38211.
func Test_issue38211(t *testing.T) {
	const ardanLabs = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
package main

import "github.com/ardanlabs/conf"

func main() {
	_ = conf.ErrHelpWanted
}
`

	modcache := t.TempDir()
	defer CleanModCache(t, modcache)

	opts := []RunOption{
		EnvVars{"GOMODCACHE": modcache},
		ProxyFiles(ardanLabsProxy),
		//WriteGoSum("."), // TODO(golang/go#74594): uncommenting this causes mysterious failure; investigate and make the error clearer (go list?)
	}

	t.Run("setup", func(t *testing.T) {
		// Forcibly populate GOMODCACHE
		// so OrganizeImports can later rely on it.
		WithOptions(opts...).Run(t, ardanLabs, func(t *testing.T, env *Env) {
			// TODO(adonovan): why doesn't RunGoCommand respect EnvVars??
			// (That was the motivation to use Sandbox.RunGoCommand
			// rather than execute go mod download directly!)
			// See comment at CleanModCache and golang/go#74595.
			environ := []string{"GOMODCACHE=" + modcache}
			_, err := env.Sandbox.RunGoCommand(env.Ctx, "", "get", []string{"github.com/ardanlabs/conf@v1.2.3"}, environ, false)
			if err != nil {
				t.Error(err)
			}
		})
	})

	WithOptions(opts...).Run(t, ardanLabs, func(t *testing.T, env *Env) {
		// Expect a "no module provides package" diagnostic.
		env.OpenFile("go.mod")
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", `"github.com/ardanlabs/conf"`),
				WithMessage("no required module provides package")),
			ReadDiagnostics("main.go", &d),
		)

		// Apply the suggested fix to make the go.mod file
		// require "github.com/ardanlabs/conf".
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.SaveBuffer("go.mod")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)

		// Comment out the sole use of conf,
		// causing an "unused import" diagnostic.
		env.RegexpReplace("main.go", "_ = conf.ErrHelpWanted", "//_ = conf.ErrHelpWanted")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", `"github.com/ardanlabs/conf"`),
				WithMessage("imported and not used")),
		)

		// Remove the import using OrganizeImports, leading
		// to an "unused require" diagnostic in the go.mod.
		env.SaveBuffer("main.go") // => OrganizeImports
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
			Diagnostics(
				env.AtRegexp("go.mod", "require github.com/ardanlabs/conf"),
				WithMessage("not used in this module")),
			ReadDiagnostics("go.mod", &d),
		)

		// Apply the suggested fix to remove the "require" directive.
		env.ApplyQuickFixes("go.mod", d.Diagnostics)
		env.SaveBuffer("go.mod")
		env.AfterChange(
			NoDiagnostics(ForFile("go.mod")),
		)

		// Uncomment the use of the import.
		// OrganizeImports should add the import.
		// Expect another "no required module provides package"
		// diagnostic, bringing us full circle.
		env.RegexpReplace("main.go", "//_ = conf.ErrHelpWanted", "_ = conf.ErrHelpWanted")
		env.SaveBuffer("main.go") // => OrganizeImports
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", `"github.com/ardanlabs/conf"`),
				WithMessage("no required module provides package")),
		)
	})
}

// Test for golang/go#38207.
func TestNewModule_Issue38207(t *testing.T) {
	const emptyFile = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
`
	WithOptions(
		ProxyFiles(ardanLabsProxy),
	).Run(t, emptyFile, func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", `package main

import "github.com/ardanlabs/conf"

func main() {
	_ = conf.ErrHelpWanted
}
`)
		env.SaveBuffer("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", `"github.com/ardanlabs/conf"`), WithMessage("no required module")),
			ReadDiagnostics("main.go", &d),
		)
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// Test for golang/go#36960.
func TestNewFileBadImports_Issue36960(t *testing.T) {
	const simplePackage = `
-- go.mod --
module mod.com

go 1.14
-- a/a1.go --
package a

import "fmt"

func _() {
	fmt.Println("hi")
}
`
	Run(t, simplePackage, func(t *testing.T, env *Env) {
		env.OpenFile("a/a1.go")
		env.CreateBuffer("a/a2.go", ``)
		env.SaveBufferWithoutActions("a/a2.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/a1.go")),
		)
		env.EditBuffer("a/a2.go", fake.NewEdit(0, 0, 0, 0, `package a`))
		env.AfterChange(
			NoDiagnostics(ForFile("a/a1.go")),
		)
	})
}

// This test tries to replicate the workflow of a user creating a new x test.
// It also tests golang/go#39315.
func TestManuallyCreatingXTest(t *testing.T) {
	// Create a package that already has a test variant (in-package test).
	const testVariant = `
-- go.mod --
module mod.com

go 1.15
-- hello/hello.go --
package hello

func Hello() {
	var x int
}
-- hello/hello_test.go --
package hello

import "testing"

func TestHello(t *testing.T) {
	var x int
	Hello()
}
`
	Run(t, testVariant, func(t *testing.T, env *Env) {
		// Open the file, triggering the workspace load.
		// There are errors in the code to ensure all is working as expected.
		env.OpenFile("hello/hello.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("hello/hello.go", "x")),
			Diagnostics(env.AtRegexp("hello/hello_test.go", "x")),
		)

		// Create an empty file with the intention of making it an x test.
		// This resembles a typical flow in an editor like VS Code, in which
		// a user would create an empty file and add content, saving
		// intermittently.
		// TODO(rstambler): There might be more edge cases here, as file
		// content can be added incrementally.
		env.CreateBuffer("hello/hello_x_test.go", ``)

		// Save the empty file (no actions since formatting will fail).
		env.SaveBufferWithoutActions("hello/hello_x_test.go")

		// Add the content. The missing import is for the package under test.
		env.EditBuffer("hello/hello_x_test.go", fake.NewEdit(0, 0, 0, 0, `package hello_test

import (
	"testing"
)

func TestHello(t *testing.T) {
	hello.Hello()
}
`))
		// Expect a diagnostic for the missing import. Save, which should
		// trigger import organization. The diagnostic should clear.
		env.AfterChange(
			Diagnostics(env.AtRegexp("hello/hello_x_test.go", "hello.Hello")),
		)
		env.SaveBuffer("hello/hello_x_test.go")
		env.AfterChange(
			NoDiagnostics(ForFile("hello/hello_x_test.go")),
		)
	})
}

// Reproduce golang/go#40690.
func TestCreateOnlyXTest(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- foo/foo.go --
package foo
-- foo/bar_test.go --
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("foo/bar_test.go")
		env.EditBuffer("foo/bar_test.go", fake.NewEdit(0, 0, 0, 0, "package foo"))
		env.Await(env.DoneWithChange())
		env.RegexpReplace("foo/bar_test.go", "package foo", `package foo_test

import "testing"

func TestX(t *testing.T) {
	var x int
}
`)
		env.AfterChange(
			Diagnostics(env.AtRegexp("foo/bar_test.go", "x")),
		)
	})
}

func TestChangePackageName(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- foo/foo.go --
package foo
-- foo/bar_test.go --
package foo_
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("foo/bar_test.go")
		env.AfterChange()
		env.RegexpReplace("foo/bar_test.go", "package foo_", "package foo_test")
		env.AfterChange(
			NoDiagnostics(ForFile("foo/bar_test.go")),
			NoDiagnostics(ForFile("foo/foo.go")),
		)
	})
}

func TestIgnoredFiles(t *testing.T) {
	const ws = `
-- go.mod --
module mod.com

go 1.12
-- _foo/x.go --
package x

var _ = foo.Bar
`
	Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("_foo/x.go")
		env.AfterChange(
			NoDiagnostics(ForFile("_foo/x.go")),
		)
	})
}

// Partially reproduces golang/go#38977, moving a file between packages.
// It also gets hit by some go command bug fixed in 1.15, but we don't
// care about that so much here.
func TestDeletePackage(t *testing.T) {
	const ws = `
-- go.mod --
module mod.com

go 1.15
-- a/a.go --
package a

const A = 1

-- b/b.go --
package b

import "mod.com/a"

const B = a.A

-- c/c.go --
package c

import "mod.com/a"

const C = a.A
`
	Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("b/b.go")
		env.Await(env.DoneWithOpen())
		// Delete c/c.go, the only file in package c.
		env.RemoveWorkspaceFile("c/c.go")

		// We should still get diagnostics for files that exist.
		env.RegexpReplace("b/b.go", `a.A`, "a.Nonexistant")
		env.AfterChange(
			Diagnostics(env.AtRegexp("b/b.go", `Nonexistant`)),
		)
	})
}

// This is a copy of the scenario_default/quickfix_empty_files.txt test from
// govim. Reproduces golang/go#39646.
func TestQuickFixEmptyFiles(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
`
	// To fully recreate the govim tests, we create files by inserting
	// a newline, adding to the file, and then deleting the newline.
	// Wait for each event to process to avoid cancellations and force
	// package loads.
	writeGoVim := func(env *Env, name, content string) {
		env.WriteWorkspaceFile(name, "")
		env.Await(env.DoneWithChangeWatchedFiles())

		env.CreateBuffer(name, "\n")
		env.Await(env.DoneWithOpen())

		env.EditBuffer(name, fake.NewEdit(1, 0, 1, 0, content))
		env.Await(env.DoneWithChange())

		env.EditBuffer(name, fake.NewEdit(0, 0, 1, 0, ""))
		env.Await(env.DoneWithChange())
	}

	const p = `package p; func DoIt(s string) {};`
	const main = `package main

import "mod.com/p"

func main() {
	p.DoIt(5)
}
`
	// A simple version of the test that reproduces most of the problems it
	// exposes.
	t.Run("short", func(t *testing.T) {
		Run(t, mod, func(t *testing.T, env *Env) {
			writeGoVim(env, "p/p.go", p)
			writeGoVim(env, "main.go", main)
			env.AfterChange(
				Diagnostics(env.AtRegexp("main.go", "5")),
			)
		})
	})

	// A full version that replicates the whole flow of the test.
	t.Run("full", func(t *testing.T) {
		Run(t, mod, func(t *testing.T, env *Env) {
			writeGoVim(env, "p/p.go", p)
			writeGoVim(env, "main.go", main)
			writeGoVim(env, "p/p_test.go", `package p

import "testing"

func TestDoIt(t *testing.T) {
	DoIt(5)
}
`)
			writeGoVim(env, "p/x_test.go", `package p_test

import (
	"testing"

	"mod.com/p"
)

func TestDoIt(t *testing.T) {
	p.DoIt(5)
}
`)
			env.AfterChange(
				Diagnostics(env.AtRegexp("main.go", "5")),
				Diagnostics(env.AtRegexp("p/p_test.go", "5")),
				Diagnostics(env.AtRegexp("p/x_test.go", "5")),
			)
			env.RegexpReplace("p/p.go", "s string", "i int")
			env.AfterChange(
				NoDiagnostics(ForFile("main.go")),
				NoDiagnostics(ForFile("p/p_test.go")),
				NoDiagnostics(ForFile("p/x_test.go")),
			)
		})
	})
}

func TestSingleFile(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.13
-- a/a.go --
package a

func _() {
	var x int
}
`
	WithOptions(
		// Empty workspace folders.
		WorkspaceFolders(),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "x")),
		)
	})
}

// Reproduces the case described in
// https://github.com/golang/go/issues/39296#issuecomment-652058883.
func TestPkgm(t *testing.T) {
	const basic = `
-- go.mod --
module mod.com

go 1.15
-- foo/foo.go --
package foo

import "fmt"

func Foo() {
	fmt.Println("")
}
`
	Run(t, basic, func(t *testing.T, env *Env) {
		env.WriteWorkspaceFile("foo/foo_test.go", `package main

func main() {

}`)
		env.OpenFile("foo/foo_test.go")
		env.RegexpReplace("foo/foo_test.go", `package main`, `package foo`)
		env.AfterChange(NoDiagnostics(ForFile("foo/foo.go")))
	})
}

func TestClosingBuffer(t *testing.T) {
	const basic = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
package main

func main() {}
`
	Run(t, basic, func(t *testing.T, env *Env) {
		env.CreateBuffer("foo.go", `package main`)
		env.AfterChange()
		env.CloseBuffer("foo.go")
		env.AfterChange(NoLogMatching(protocol.Info, "packages=0"))
	})
}

// Reproduces golang/go#38424.
func TestCutAndPaste(t *testing.T) {
	const basic = `
-- go.mod --
module mod.com

go 1.14
-- main2.go --
package main
`
	Run(t, basic, func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", "")
		env.Await(env.DoneWithOpen())

		env.SaveBufferWithoutActions("main.go")
		env.Await(env.DoneWithSave(), env.DoneWithChangeWatchedFiles())

		env.EditBuffer("main.go", fake.NewEdit(0, 0, 0, 0, `package main

func main() {
}
`))
		env.Await(env.DoneWithChange())

		env.SaveBuffer("main.go")
		env.Await(env.DoneWithSave(), env.DoneWithChangeWatchedFiles())

		env.EditBuffer("main.go", fake.NewEdit(0, 0, 4, 0, ""))
		env.Await(env.DoneWithChange())

		env.EditBuffer("main.go", fake.NewEdit(0, 0, 0, 0, `package main

func main() {
	var x int
}
`))
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "x")),
		)
	})
}

// Reproduces golang/go#39763.
func TestInvalidPackageName(t *testing.T) {
	const pkgDefault = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package default

func main() {}
`
	Run(t, pkgDefault, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", "default"),
				WithMessage("expected 'IDENT'"),
			),
		)
	})
}

// This test verifies that the workspace scope is effectively limited to the
// workspace folder, if expandWorkspaceToModule is set.
func TestExpandWorkspaceToModule(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- a/main.go --
package main

func main() {}
-- main.go --
package main

func main() {
	var x int
}
`
	WithOptions(
		WorkspaceFolders("a"),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "x")),
		)
	})
	WithOptions(
		WorkspaceFolders("a"),
		Settings{"expandWorkspaceToModule": false},
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// This test verifies that the workspace scope is effectively limited to the
// set of active modules.
//
// We should not get diagnostics or file watching patterns for paths outside of
// the active workspace.
func TestWorkspaceModules(t *testing.T) {
	const mod = `
-- go.work --
go 1.18

use a
-- a/go.mod --
module mod.com/a

go 1.12
-- a/a.go --
package a

func _() {
	var x int
}
-- b/go.mod --
module mod.com/b

go 1.18
`
	WithOptions(
		Settings{
			"subdirWatchPatterns": "on",
		},
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		// Writing this file may cause the snapshot to 'know' about the file b, but
		// that shouldn't cause it to watch the 'b' directory.
		env.WriteWorkspaceFile("b/b.go", `package b

func _() {
	var x int
}
`)
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "x")),
			NoDiagnostics(ForFile("b/b.go")),
			FileWatchMatching("a$"),
			NoFileWatchMatching("b$"),
		)
	})
}

func TestSimplifyCompositeLitDiagnostic(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

type t struct {
	msg string
}

func main() {
	x := []t{t{"msg"}}
	fmt.Println(x)
}
`

	WithOptions(
		Settings{"staticcheck": true},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", `t{"msg"}`), WithMessage("redundant type")),
			ReadDiagnostics("main.go", &d),
		)
		if tags := d.Diagnostics[0].Tags; len(tags) == 0 || tags[0] != protocol.Unnecessary {
			t.Errorf("wanted Unnecessary tag on diagnostic, got %v", tags)
		}
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

// Test some secondary diagnostics
func TestSecondaryDiagnostics(t *testing.T) {
	const dir = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main
func main() {
	panic("not here")
}
-- other.go --
package main
func main() {}
`
	Run(t, dir, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OpenFile("other.go")
		var mainDiags, otherDiags protocol.PublishDiagnosticsParams
		env.AfterChange(
			ReadDiagnostics("main.go", &mainDiags),
			ReadDiagnostics("other.go", &otherDiags),
		)
		if len(mainDiags.Diagnostics) != 1 {
			t.Fatalf("main.go, got %d diagnostics, expected 1", len(mainDiags.Diagnostics))
		}
		keep := mainDiags.Diagnostics[0]
		if len(otherDiags.Diagnostics) != 1 {
			t.Fatalf("other.go: got %d diagnostics, expected 1", len(otherDiags.Diagnostics))
		}
		if len(otherDiags.Diagnostics[0].RelatedInformation) != 1 {
			t.Fatalf("got %d RelatedInformations, expected 1", len(otherDiags.Diagnostics[0].RelatedInformation))
		}
		// check that the RelatedInformation matches the error from main.go
		c := otherDiags.Diagnostics[0].RelatedInformation[0]
		if c.Location.Range != keep.Range {
			t.Errorf("locations don't match. Got %v expected %v", c.Location.Range, keep.Range)
		}
	})
}

func TestOrphanedFiles(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

func main() {
	var x int
}
-- a/a_exclude.go --
// +build exclude

package a

func _() {
	var x int
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "x")),
		)
		env.OpenFile("a/a_exclude.go")

		loadOnce := LogMatching(protocol.Info, "query=.*file=.*a_exclude.go", 1, false)

		// can't use OnceMet or AfterChange as logs are async
		env.Await(loadOnce)
		// ...but ensure that the change has been fully processed before editing.
		// Otherwise, there may be a race where the snapshot is cloned before all
		// state changes resulting from the load have been processed
		// (golang/go#61521).
		env.AfterChange()

		// Check that orphaned files are not reloaded, by making a change in
		// a.go file and confirming that the workspace diagnosis did not reload
		// a_exclude.go.
		//
		// This is racy (but fails open) because logs are asynchronous to other LSP
		// operations. There's a chance gopls _did_ log, and we just haven't seen
		// it yet.
		env.RegexpReplace("a/a.go", "package a", "package a // arbitrary comment")
		env.AfterChange(loadOnce)
	})
}

func TestSwig(t *testing.T) {
	if _, err := exec.LookPath("swig"); err != nil {
		t.Skip("skipping test: swig not available")
	}
	if _, err := exec.LookPath("g++"); err != nil {
		t.Skip("skipping test: g++ not available")
	}

	const mod = `
-- go.mod --
module mod.com

go 1.12
-- pkg/simple/export_swig.go --
package simple

func ExportSimple(x, y int) int {
	return Gcd(x, y)
}
-- pkg/simple/simple.swigcxx --
%module simple

%inline %{
extern int gcd(int x, int y)
{
  int g;
  g = y;
  while (x > 0) {
    g = x;
    x = y % x;
    y = g;
  }
  return g;
}
%}
-- main.go --
package a

func main() {
	var x int
}
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			NoDiagnostics(WithMessage("illegal character U+0023 '#'")),
		)
	})
}

// When foo_test.go is opened, gopls will object to the borked package name.
// This test asserts that when the package name is fixed, gopls will soon after
// have no more complaints about it.
// https://github.com/golang/go/issues/41061
func TestRenamePackage(t *testing.T) {
	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/blah/blah.go --
package hello

const Name = "Hello"
`

	const contents = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "example.com/blah"

func main() {
	blah.Hello()
}
-- bob.go --
package main
-- foo/foo.go --
package foo
-- foo/foo_test.go --
package foo_
`

	WithOptions(
		ProxyFiles(proxy),
		InGOPATH(),
		EnvVars{"GO111MODULE": "off"},
	).Run(t, contents, func(t *testing.T, env *Env) {
		// Simulate typing character by character.
		env.OpenFile("foo/foo_test.go")
		env.Await(env.DoneWithOpen())
		env.RegexpReplace("foo/foo_test.go", "_", "_t")
		env.Await(env.DoneWithChange())
		env.RegexpReplace("foo/foo_test.go", "_t", "_test")
		env.AfterChange(
			NoDiagnostics(ForFile("foo/foo_test.go")),
			NoOutstandingWork(IgnoreTelemetryPromptWork),
		)
	})
}

// TestProgressBarErrors confirms that critical workspace load errors are shown
// and updated via progress reports.
func TestProgressBarErrors(t *testing.T) {
	const pkg = `
-- go.mod --
modul mod.com

go 1.12
-- main.go --
package main
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.AfterChange(
			OutstandingWork(server.WorkspaceLoadFailure, "unknown directive"),
		)
		env.EditBuffer("go.mod", fake.NewEdit(0, 0, 3, 0, `module mod.com

go 1.hello
`))
		// As of golang/go#42529, go.mod changes do not reload the workspace until
		// they are saved.
		env.SaveBufferWithoutActions("go.mod")
		env.AfterChange(
			OutstandingWork(server.WorkspaceLoadFailure, "invalid go version"),
		)
		env.RegexpReplace("go.mod", "go 1.hello", "go 1.12")
		env.SaveBufferWithoutActions("go.mod")
		env.AfterChange(
			NoOutstandingWork(IgnoreTelemetryPromptWork),
		)
	})
}

func TestDeleteDirectory(t *testing.T) {
	const mod = `
-- bob/bob.go --
package bob

func Hello() {
	var x int
}
-- go.mod --
module mod.com
-- cmd/main.go --
package main

import "mod.com/bob"

func main() {
	bob.Hello()
}
`
	WithOptions(
		Settings{
			// Now that we don't watch subdirs by default (except for VS Code),
			// we must explicitly ask gopls to requests subdir watch patterns.
			"subdirWatchPatterns": "on",
		},
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			FileWatchMatching("bob"),
		)
		env.RemoveWorkspaceFile("bob")
		env.AfterChange(
			Diagnostics(env.AtRegexp("cmd/main.go", `"mod.com/bob"`)),
			NoDiagnostics(ForFile("bob/bob.go")),
			NoFileWatchMatching("bob"),
		)
	})
}

// Confirms that circular imports are tested and reported.
func TestCircularImports(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- self/self.go --
package self

import _ "mod.com/self"
func Hello() {}
-- double/a/a.go --
package a

import _ "mod.com/double/b"
-- double/b/b.go --
package b

import _ "mod.com/double/a"
-- triple/a/a.go --
package a

import _ "mod.com/triple/b"
-- triple/b/b.go --
package b

import _ "mod.com/triple/c"
-- triple/c/c.go --
package c

import _ "mod.com/triple/a"
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("self/self.go", `_ "mod.com/self"`), WithMessage("import cycle not allowed")),
			Diagnostics(env.AtRegexp("double/a/a.go", `_ "mod.com/double/b"`), WithMessage("import cycle not allowed")),
			Diagnostics(env.AtRegexp("triple/a/a.go", `_ "mod.com/triple/b"`), WithMessage("import cycle not allowed")),
		)
	})
}

// Tests golang/go#46667: deleting a problematic import path should resolve
// import cycle errors.
func TestResolveImportCycle(t *testing.T) {
	const mod = `
-- go.mod --
module mod.test

go 1.16
-- a/a.go --
package a

import "mod.test/b"

const A = b.A
const B = 2
-- b/b.go --
package b

import "mod.test/a"

const A = 1
const B = a.B
	`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.OpenFile("b/b.go")
		env.AfterChange(
			// The Go command sometimes tells us about only one of the import cycle
			// errors below. Also, sometimes we get an error during type checking
			// instead of during list, due to missing metadata. This is likely due to
			// a race.
			// For robustness of this test, succeed if we get any reasonable error.
			//
			// TODO(golang/go#52904): we should get *both* of these errors.
			// TODO(golang/go#64899): we should always get an import cycle error
			// rather than a missing metadata error.
			AnyOf(
				Diagnostics(env.AtRegexp("a/a.go", `"mod.test/b"`)),
				Diagnostics(env.AtRegexp("b/b.go", `"mod.test/a"`)),
			),
		)
		env.RegexpReplace("b/b.go", `const B = a\.B`, "")
		env.SaveBuffer("b/b.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
			NoDiagnostics(ForFile("b/b.go")),
		)
	})
}

func TestBadImport(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import (
	_ "nosuchpkg"
)
`
	t.Run("module", func(t *testing.T) {
		Run(t, mod, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("main.go", `"nosuchpkg"`), WithMessage(`could not import nosuchpkg (no required module provides package "nosuchpkg"`)),
			)
		})
	})
	t.Run("GOPATH", func(t *testing.T) {
		WithOptions(
			InGOPATH(),
			EnvVars{"GO111MODULE": "off"},
			Modes(Default),
		).Run(t, mod, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("main.go", `"nosuchpkg"`), WithMessage(`cannot find package "nosuchpkg"`)),
			)
		})
	})
}

func TestNestedModules(t *testing.T) {
	const proxy = `
-- nested.com@v1.0.0/go.mod --
module nested.com

go 1.12
-- nested.com@v1.0.0/hello/hello.go --
package hello

func Hello() {}
`

	const nested = `
-- go.mod --
module mod.com

go 1.12

require nested.com v1.0.0
-- main.go --
package main

import "nested.com/hello"

func main() {
	hello.Hello()
}
-- nested/go.mod --
module nested.com

-- nested/hello/hello.go --
package hello

func Hello() {
	helloHelper()
}
-- nested/hello/hello_helper.go --
package hello

func helloHelper() {}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
		Modes(Default),
	).Run(t, nested, func(t *testing.T, env *Env) {
		// Expect a diagnostic in a nested module.
		env.OpenFile("nested/hello/hello.go")
		env.AfterChange(
			NoDiagnostics(ForFile("nested/hello/hello.go")),
		)
		loc := env.FirstDefinition(env.RegexpSearch("nested/hello/hello.go", "helloHelper"))
		want := "nested/hello/hello_helper.go"
		if got := env.Sandbox.Workdir.URIToPath(loc.URI); got != want {
			t.Errorf("Definition() returned %q, want %q", got, want)
		}
	})
}

func TestAdHocPackagesReloading(t *testing.T) {
	const nomod = `
-- main.go --
package main

func main() {}
`
	Run(t, nomod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.RegexpReplace("main.go", "{}", "{ var x int; }") // simulate typing
		env.AfterChange(NoLogMatching(protocol.Info, "packages=1"))
	})
}

func TestBuildTagChange(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo.go --
// decoy comment
// +build hidden
// decoy comment

package foo
var Foo = 1
-- bar.go --
package foo
var Bar = Foo
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		env.AfterChange(Diagnostics(env.AtRegexp("bar.go", `Foo`)))
		env.RegexpReplace("foo.go", `\+build`, "")
		env.AfterChange(NoDiagnostics(ForFile("bar.go")))
	})

}

func TestIssue44736(t *testing.T) {
	const files = `
	-- go.mod --
module blah.com

go 1.16
-- main.go --
package main

import "fmt"

func main() {
	asdf
	fmt.Printf("This is a test %v")
	fdas
}
-- other.go --
package main

`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OpenFile("other.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "asdf")),
			Diagnostics(env.AtRegexp("main.go", "fdas")),
		)
		env.SetBufferContent("other.go", "package main\n\nasdf")
		// The new diagnostic in other.go should not suppress diagnostics in main.go.
		env.AfterChange(
			Diagnostics(env.AtRegexp("other.go", "asdf"), WithMessage("expected declaration")),
			Diagnostics(env.AtRegexp("main.go", "asdf")),
		)
	})
}

func TestInitialization(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- main.go --
package main
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.Await(env.DoneWithOpen())
		env.RegexpReplace("go.mod", "module", "modul")
		env.SaveBufferWithoutActions("go.mod")
		env.AfterChange(
			NoLogMatching(protocol.Error, "initial workspace load failed"),
		)
	})
}

// This test confirms that the view does not reinitialize when a go.mod file is
// opened.
func TestNoReinitialize(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.Await(
			// Check that we have only loaded "<dir>/..." once.
			// Log messages are asynchronous to other events on the LSP stream, so we
			// can't use OnceMet or AfterChange here.
			LogMatching(protocol.Info, `.*query=.*\.\.\..*`, 1, false),
		)
	})
}

func TestLangVersion(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

const C = 0b10
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `0b10`), WithMessage("go1.13 or later")),
		)
		env.WriteWorkspaceFile("go.mod", "module mod.com \n\ngo 1.13\n")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

func TestNoQuickFixForUndeclaredConstraint(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

func F[T C](_ T) {
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		var d protocol.PublishDiagnosticsParams
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `C`)),
			ReadDiagnostics("main.go", &d),
		)
		if fixes := env.GetQuickFixes("main.go", d.Diagnostics); len(fixes) != 0 {
			t.Errorf("got quick fixes %v, wanted none", fixes)
		}
	})
}

func TestEditGoDirective(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- main.go --
package main

func F[T any](_ T) {
}
`
	Run(t, files, func(_ *testing.T, env *Env) { // Create a new workspace-level directory and empty file.
		var d protocol.PublishDiagnosticsParams
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `T any`), WithMessage("type parameter")),
			ReadDiagnostics("main.go", &d),
		)

		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

func TestEditGoDirectiveWorkspace(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- go.work --
go 1.18

use .
-- main.go --
package main

func F[T any](_ T) {
}
`
	Run(t, files, func(_ *testing.T, env *Env) { // Create a new workspace-level directory and empty file.
		var d protocol.PublishDiagnosticsParams

		// We should have a diagnostic because generics are not supported at 1.16.
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `T any`), WithMessage("type parameter")),
			ReadDiagnostics("main.go", &d),
		)

		// This diagnostic should have a quick fix to edit the go version.
		env.ApplyQuickFixes("main.go", d.Diagnostics)

		// Once the edit is applied, the problematic diagnostics should be
		// resolved.
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// This test demonstrates that analysis facts are correctly propagated
// across packages.
func TestInterpackageAnalysis(t *testing.T) {
	const src = `
-- go.mod --
module example.com
-- a/a.go --
package a

import "example.com/b"

func _() {
	new(b.B).Printf("%d", "s") // printf error
}

-- b/b.go --
package b

import "example.com/c"

type B struct{}

func (B) Printf(format string, args ...interface{}) {
	c.MyPrintf(format, args...)
}

-- c/c.go --
package c

import "fmt"

func MyPrintf(format string, args ...interface{}) {
	fmt.Printf(format, args...)
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("a/a.go", "%d"),
				WithMessage("format %d has arg \"s\" of wrong type string"),
			),
		)
	})
}

// This test ensures that only Analyzers with RunDespiteErrors=true
// are invoked on a package that would not compile, even if the errors
// are distant and localized.
func TestErrorsThatPreventAnalysis(t *testing.T) {
	const src = `
-- go.mod --
module example.com
-- a/a.go --
package a

import "fmt"
import "sync"
import _ "example.com/b"

func _() {
	// The copylocks analyzer (RunDespiteErrors, FactTypes={}) does run.
	var mu sync.Mutex
	mu2 := mu // copylocks error, reported
	_ = &mu2

	// The printf analyzer (!RunDespiteErrors, FactTypes!={}) does not run:
	//  (c, printf) failed because of type error in c
	//  (b, printf) and (a, printf) do not run because of failed prerequisites.
	fmt.Printf("%d", "s") // printf error, unreported

	// The bools analyzer (!RunDespiteErrors, FactTypes={}) does not run:
	var cond bool
	_ = cond != true && cond != true // bools error, unreported
}

-- b/b.go --
package b

import _ "example.com/c"

-- c/c.go --
package c

var _ = 1 / "" // type error

`
	Run(t, src, func(t *testing.T, env *Env) {
		var diags protocol.PublishDiagnosticsParams
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "mu2 := (mu)"), WithMessage("assignment copies lock value")),
			ReadDiagnostics("a/a.go", &diags))

		// Assert that there were no other diagnostics.
		// In particular:
		// - "fmt.Printf" does not trigger a [printf] finding;
		// - "cond != true" does not trigger a [bools] finding.
		//
		// We use this check in preference to NoDiagnosticAtRegexp
		// as it is robust in case of minor mistakes in the position
		// regexp, and because it reports unexpected diagnostics.
		if got, want := len(diags.Diagnostics), 1; got != want {
			t.Errorf("got %d diagnostics in a/a.go, want %d:", got, want)
			for i, diag := range diags.Diagnostics {
				t.Logf("Diagnostics[%d] = %+v", i, diag)
			}
		}
	})
}

// This test demonstrates the deprecated symbol analyzer
// produces deprecation notices with expected severity and tags.
func TestDeprecatedAnalysis(t *testing.T) {
	const src = `
-- go.mod --
module example.com
-- a/a.go --
package a

import "example.com/b"

func _() {
	new(b.B).Obsolete() // deprecated
}

-- b/b.go --
package b

type B struct{}

// Deprecated: use New instead.
func (B) Obsolete() {}

func (B) New() {}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("a/a.go", "new.*Obsolete"),
				WithMessage("use New instead."),
				WithSeverityTags("deprecated", protocol.SeverityHint, []protocol.DiagnosticTag{protocol.Deprecated}),
			),
		)
	})
}

func TestDiagnosticsOnlyOnSaveFile(t *testing.T) {
	// This functionality is broken because the new orphaned file diagnostics
	// logic wants to publish diagnostics for changed files, independent of any
	// snapshot diagnostics pass, and this causes stale diagnostics to be
	// invalidated.
	//
	// We can fix this behavior more correctly by also honoring the
	// diagnosticsTrigger in DiagnoseOrphanedFiles, but that would require
	// resolving configuration that is independent of the snapshot. In other
	// words, we need to figure out which cache.Folder.Options applies to the
	// changed file, even if it does not have a snapshot.
	t.Skip("temporary skip for golang/go#57979: revisit after zero-config logic is in place")

	const onlyMod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
	Foo()
}
-- foo.go --
package main

func Foo() {}
`
	WithOptions(
		Settings{
			"diagnosticsTrigger": "Save",
		},
	).Run(t, onlyMod, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		env.RegexpReplace("foo.go", "(Foo)", "Bar") // Makes reference to Foo undefined/undeclared.
		env.AfterChange(NoDiagnostics())            // No diagnostics update until file save.

		env.SaveBuffer("foo.go")
		// Compiler's error message about undeclared names vary depending on the version,
		// but must be explicit about the problematic name.
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", "Foo"), WithMessage("Foo")))

		env.OpenFile("main.go")
		env.RegexpReplace("main.go", "(Foo)", "Bar")
		// No diagnostics update until file save. That results in outdated diagnostic.
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", "Bar"), WithMessage("Foo")))

		env.SaveBuffer("main.go")
		env.AfterChange(NoDiagnostics())
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/golist_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"testing"

	"golang.org/x/tools/gopls/internal/cache"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/internal/testenv"
)

func TestGoListErrors(t *testing.T) {
	testenv.NeedsTool(t, "cgo")

	const src = `
-- go.mod --
module a.com

go 1.18
-- a/a.go --
package a

import
-- c/c.go --
package c

/*
int fortythree() { return 42; }
*/
import "C"

func Foo() {
	print(C.fortytwo())
}
-- p/p.go --
package p

import "a.com/q"

const P = q.Q + 1
-- q/q.go --
package q

import "a.com/p"

const Q = p.P + 1
`

	Run(t, src, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(
				env.AtRegexp("a/a.go", "import\n()"),
				FromSource(string(cache.ParseError)),
			),
			Diagnostics(
				AtPosition("c/c.go", 0, 0),
				FromSource(string(cache.ListError)),
				WithMessage("may indicate failure to perform cgo processing"),
			),
			Diagnostics(
				env.AtRegexp("p/p.go", `"a.com/q"`),
				FromSource(string(cache.ListError)),
				WithMessage("import cycle not allowed"),
			),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/gopackagesdriver_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test that the import error does not mention GOPATH when building with
// go/packages driver.
func TestBrokenWorkspace_GOPACKAGESDRIVER(t *testing.T) {
	// A go.mod file is actually needed here, because the fake go/packages driver
	// uses go list behind the scenes, and we load go/packages driver workspaces
	// with ./...
	const files = `
-- go.mod --
module m
go 1.12

-- a.go --
package foo

import "mod.com/hello"
`
	WithOptions(
		FakeGoPackagesDriver(t),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("a.go", `"mod.com`),
				WithMessage("go/packages driver"),
			),
		)
		// Deleting the import removes the error.
		env.RegexpReplace("a.go", `import "mod.com/hello"`, "")
		env.AfterChange(
			NoDiagnostics(ForFile("a.go")),
		)
	})
}

func TestValidImportCheck_GoPackagesDriver(t *testing.T) {
	const files = `
-- go.work --
use .

-- go.mod --
module example.com
go 1.0

-- a/a.go --
package a
import _ "example.com/b/internal/c"

-- b/internal/c/c.go --
package c
`

	// Note that 'go list' produces an error ("use of internal package %q not allowed")
	// and gopls produces another ("invalid use of internal package %q") with source=compiler.
	// Here we assert that the second one is not reported with a go/packages driver.
	// (We don't assert that the first is missing, because the test driver wraps go list!)

	// go list
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(Diagnostics(WithMessage(`invalid use of internal package "example.com/b/internal/c"`)))
	})

	// test driver
	WithOptions(
		FakeGoPackagesDriver(t),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(NoDiagnostics(WithMessage(`invalid use of internal package "example.com/b/internal/c"`)))
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/invalidation_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"fmt"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test for golang/go#50267: diagnostics should be re-sent after a file is
// opened.
func TestDiagnosticsAreResentAfterCloseOrOpen(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- main.go --
package main

func _() {
	x := 2
}
`
	Run(t, files, func(t *testing.T, env *Env) { // Create a new workspace-level directory and empty file.
		env.OpenFile("main.go")
		var afterOpen protocol.PublishDiagnosticsParams
		env.AfterChange(
			ReadDiagnostics("main.go", &afterOpen),
		)
		env.CloseBuffer("main.go")
		var afterClose protocol.PublishDiagnosticsParams
		env.AfterChange(
			ReadDiagnostics("main.go", &afterClose),
		)
		if afterOpen.Version == afterClose.Version {
			t.Errorf("publishDiagnostics: got the same version after closing (%d) as after opening", afterOpen.Version)
		}
		env.OpenFile("main.go")
		var afterReopen protocol.PublishDiagnosticsParams
		env.AfterChange(
			ReadDiagnostics("main.go", &afterReopen),
		)
		if afterReopen.Version == afterClose.Version {
			t.Errorf("pubslishDiagnostics: got the same version after reopening (%d) as after closing", afterClose.Version)
		}
	})
}

// Test for the "chatty" diagnostics: gopls should re-send diagnostics for
// changed files after every file change, even if diagnostics did not change.
func TestChattyDiagnostics(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- main.go --
package main

func _() {
	x := 2
}

// Irrelevant comment #0
`

	Run(t, files, func(t *testing.T, env *Env) { // Create a new workspace-level directory and empty file.
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			ReadDiagnostics("main.go", &d),
		)

		if len(d.Diagnostics) != 1 {
			t.Fatalf("len(Diagnostics) = %d, want 1", len(d.Diagnostics))
		}
		msg := d.Diagnostics[0].Message

		for i := range 5 {
			before := d.Version
			env.RegexpReplace("main.go", "Irrelevant comment #.", fmt.Sprintf("Irrelevant comment #%d", i))
			env.AfterChange(
				ReadDiagnostics("main.go", &d),
			)

			if d.Version == before {
				t.Errorf("after change, got version %d, want new version", d.Version)
			}

			// As a sanity check, make sure we have the same diagnostic.
			if len(d.Diagnostics) != 1 {
				t.Fatalf("len(Diagnostics) = %d, want 1", len(d.Diagnostics))
			}
			newMsg := d.Diagnostics[0].Message
			if newMsg != msg {
				t.Errorf("after change, got message %q, want %q", newMsg, msg)
			}
		}
	})
}

func TestCreatingPackageInvalidatesDiagnostics_Issue66384(t *testing.T) {
	const files = `
-- go.mod --
module example.com

go 1.15
-- main.go --
package main

import "example.com/pkg"

func main() {
	var _ pkg.Thing
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `"example.com/pkg"`)),
		)
		// In order for this test to reproduce golang/go#66384, we have to create
		// the buffer, wait for loads, and *then* "type out" the contents. Doing so
		// reproduces the conditions of the bug report, that typing the package
		// name itself doesn't invalidate the broken import.
		env.CreateBuffer("pkg/pkg.go", "")
		env.AfterChange()
		env.EditBuffer("pkg/pkg.go", protocol.TextEdit{NewText: "package pkg\ntype Thing struct{}\n"})
		env.AfterChange()
		env.SaveBuffer("pkg/pkg.go")
		env.AfterChange(NoDiagnostics())
		env.SetBufferContent("pkg/pkg.go", "package pkg")
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", "Thing")))
	})
}


================================================
FILE: gopls/internal/test/integration/diagnostics/undeclared_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diagnostics

import (
	"slices"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestUndeclaredDiagnostics(t *testing.T) {
	src := `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

func _() int {
	return x
}
-- b/b.go --
package b

func _() int {
	var y int
	y = y
	return y
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		isUnnecessary := func(diag protocol.Diagnostic) bool {
			return slices.Contains(diag.Tags, protocol.Unnecessary)
		}

		// 'x' is undeclared, but still necessary.
		env.OpenFile("a/a.go")
		var adiags protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "x")),
			ReadDiagnostics("a/a.go", &adiags),
		)
		if got := len(adiags.Diagnostics); got != 1 {
			t.Errorf("len(Diagnostics) = %d, want 1", got)
		}
		if diag := adiags.Diagnostics[0]; isUnnecessary(diag) {
			t.Errorf("%v tagged unnecessary, want necessary", diag)
		}

		// 'y = y' is pointless, and should be detected as unnecessary.
		env.OpenFile("b/b.go")
		var bdiags protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("b/b.go", "y = y")),
			ReadDiagnostics("b/b.go", &bdiags),
		)
		if got := len(bdiags.Diagnostics); got != 1 {
			t.Errorf("len(Diagnostics) = %d, want 1", got)
		}
		if diag := bdiags.Diagnostics[0]; !isUnnecessary(diag) {
			t.Errorf("%v tagged necessary, want unnecessary", diag)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/doc.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package integration provides a framework for writing integration tests of gopls.
//
// The behaviors that matter to users, and the scenarios they
// typically describe in bug report, are usually expressed in terms of
// editor interactions. For example: "When I open my editor in this
// directory, navigate to this file, and change this line, I get a
// diagnostic that doesn't make sense". The integration package
// provides an API for gopls maintainers to express these types of
// user interactions in ordinary Go tests, validate them, and run them
// in a variety of execution modes.
//
// # Test package setup
//
// The integration test package uses a couple of uncommon patterns to reduce
// boilerplate in test bodies. First, it is intended to be imported as "." so
// that helpers do not need to be qualified. Second, it requires some setup
// that is currently implemented in the integration.Main function, which must be
// invoked by TestMain. Therefore, a minimal integration testing package looks
// like this:
//
//	package feature
//
//	import (
//		"fmt"
//		"testing"
//
//		"golang.org/x/tools/gopls/internal/hooks"
//		. "golang.org/x/tools/gopls/internal/test/integration"
//	)
//
//	func TestMain(m *testing.M) {
//		os.Exit(Main(m, hooks.Options))
//	}
//
// # Writing a simple integration test
//
// To run an integration test use the integration.Run function, which accepts a
// txtar-encoded archive defining the initial workspace state. This function
// sets up the workspace in a temporary directory, creates a fake text editor,
// starts gopls, and initializes an LSP session. It then invokes the provided
// test function with an *Env encapsulating the newly created
// environment. Because gopls may be run in various modes (as a sidecar or
// daemon process, with different settings), the test runner may perform this
// process multiple times, re-running the test function each time with a new
// environment.
//
//	func TestOpenFile(t *testing.T) {
//		const files = `
//	-- go.mod --
//	module mod.com
//
//	go 1.12
//	-- foo.go --
//	package foo
//	`
//		Run(t, files, func(t *testing.T, env *Env) {
//			env.OpenFile("foo.go")
//		})
//	}
//
// # Configuring integration test execution
//
// The integration package exposes several options that affect the setup process
// described above. To use these options, use the WithOptions function:
//
//	WithOptions(opts...).Run(...)
//
// See options.go for a full list of available options.
//
// # Operating on editor state
//
// To operate on editor state within the test body, the Env type provides
// access to the workspace directory (Env.SandBox), text editor (Env.Editor),
// LSP server (Env.Server), and 'awaiter' (Env.Awaiter).
//
// In most cases, operations on these primitive building blocks of the
// integration test environment expect a Context (which should be a child of
// env.Ctx), and return an error. To avoid boilerplate, the Env exposes a set
// of wrappers in wrappers.go for use in scripting:
//
//	env.CreateBuffer("c/c.go", "")
//	env.EditBuffer("c/c.go", editor.Edit{
//		Text: `package c`,
//	})
//
// These wrappers thread through Env.Ctx, and call t.Fatal on any errors.
//
// # Expressing expectations
//
// The general pattern for an integration test is to script interactions with the
// fake editor and sandbox, and assert that gopls behaves correctly after each
// state change. Unfortunately, this is complicated by the fact that state
// changes are communicated to gopls via unidirectional client->server
// notifications (didOpen, didChange, etc.), and resulting gopls behavior such
// as diagnostics, logs, or messages is communicated back via server->client
// notifications. Therefore, within integration tests we must be able to say "do
// this, and then eventually gopls should do that". To achieve this, the
// integration package provides a framework for expressing conditions that must
// eventually be met, in terms of the Expectation type.
//
// To express the assertion that "eventually gopls must meet these
// expectations", use env.Await(...):
//
//	env.RegexpReplace("x/x.go", `package x`, `package main`)
//	env.Await(env.DiagnosticAtRegexp("x/main.go", `fmt`))
//
// Await evaluates the provided expectations atomically, whenever the client
// receives a state-changing notification from gopls. See expectation.go for a
// full list of available expectations.
//
// A problem with this model is that if gopls never meets the provided
// expectations, the test runner will hang until the test timeout
// (which defaults to 10m). There are two ways to work around this
// poor behavior:
//
//  1. Use a precondition to define precisely when we expect conditions to be
//     met. Gopls provides the OnceMet(precondition, expectations...) pattern
//     to express ("once this precondition is met, the following expectations
//     must all hold"). To instrument preconditions, gopls uses verbose
//     progress notifications to inform the client about ongoing work (see
//     CompletedWork). The most common precondition is to wait for gopls to be
//     done processing all change notifications, for which the integration package
//     provides the AfterChange helper. For example:
//
//     // We expect diagnostics to be cleared after gopls is done processing the
//     // didSave notification.
//     env.SaveBuffer("a/go.mod")
//     env.AfterChange(EmptyDiagnostics("a/go.mod"))
//
//  2. Set a shorter timeout during development, if you expect to be breaking
//     tests. By setting the environment variable GOPLS_INTEGRATION_TEST_TIMEOUT=5s,
//     integration tests will time out after 5 seconds.
//
// # Tips & Tricks
//
// Here are some tips and tricks for working with integration tests:
//
//  1. Set the environment variable GOPLS_INTEGRRATION_TEST_TIMEOUT=5s during development.
//  2. Run tests with  -short. This will only run integration tests in the
//     default gopls execution mode.
//  3. Use capture groups to narrow regexp positions. All regular-expression
//     based positions (such as DiagnosticAtRegexp) will match the position of
//     the first capture group, if any are provided. This can be used to
//     identify a specific position in the code for a pattern that may occur in
//     multiple places. For example `var (mu) sync.Mutex` matches the position
//     of "mu" within the variable declaration.
//  4. Read diagnostics into a variable to implement more complicated
//     assertions about diagnostic state in the editor. To do this, use the
//     pattern OnceMet(precondition, ReadDiagnostics("file.go", &d)) to capture
//     the current diagnostics as soon as the precondition is met. This is
//     preferable to accessing the diagnostics directly, as it avoids races.
package integration


================================================
FILE: gopls/internal/test/integration/env.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"context"
	"fmt"
	"net/http/httptest"
	"os"
	"os/exec"
	"strings"
	"sync"
	"sync/atomic"
	"testing"

	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
)

// Env holds the building blocks of an editor testing environment, providing
// wrapper methods that hide the boilerplate of plumbing contexts and checking
// errors.
// Call [Env.Shutdown] for cleaning up resources after the test.
type Env struct {
	TB  testing.TB
	Ctx context.Context

	// Most tests should not need to access the scratch area, editor, server, or
	// connection, but they are available if needed.
	Sandbox *fake.Sandbox
	Server  servertest.Connector

	// Editor is owned by the Env, and shut down
	Editor *fake.Editor

	Awaiter *Awaiter

	// MCPServer, MCPSession and EventChan is owned by the Env, and shut down.
	// Only available if the test enables MCP Server.
	MCPServer  *httptest.Server
	MCPSession *mcp.ClientSession
}

// nextAwaiterRegistration is used to create unique IDs for various Awaiter
// registrations.
var nextAwaiterRegistration atomic.Uint64

// An Awaiter keeps track of relevant LSP state, so that it may be asserted
// upon with Expectations.
//
// Wire it into a fake.Editor using Awaiter.Hooks().
//
// TODO(rfindley): consider simply merging Awaiter with the fake.Editor. It
// probably is not worth its own abstraction.
type Awaiter struct {
	workdir *fake.Workdir

	mu sync.Mutex
	// For simplicity, each waiter gets a unique ID.
	state   State
	waiters map[uint64]*condition

	// collectors map a registration to the collection of messages that have been
	// received since the registration was created.
	docCollectors     map[uint64][]*protocol.ShowDocumentParams
	messageCollectors map[uint64][]*protocol.ShowMessageParams
}

func NewAwaiter(workdir *fake.Workdir) *Awaiter {
	return &Awaiter{
		workdir: workdir,
		state: State{
			diagnostics:   make(map[string]*protocol.PublishDiagnosticsParams),
			work:          make(map[protocol.ProgressToken]*workProgress),
			startedWork:   make(map[string]uint64),
			completedWork: make(map[string]uint64),
		},
		waiters: make(map[uint64]*condition),
	}
}

// Hooks returns LSP client hooks required for awaiting asynchronous expectations.
func (a *Awaiter) Hooks() fake.ClientHooks {
	return fake.ClientHooks{
		OnDiagnostics:            a.onDiagnostics,
		OnLogMessage:             a.onLogMessage,
		OnWorkDoneProgressCreate: a.onWorkDoneProgressCreate,
		OnProgress:               a.onProgress,
		OnShowDocument:           a.onShowDocument,
		OnShowMessage:            a.onShowMessage,
		OnShowMessageRequest:     a.onShowMessageRequest,
		OnRegisterCapability:     a.onRegisterCapability,
		OnUnregisterCapability:   a.onUnregisterCapability,
	}
}

// State encapsulates the server state TODO: explain more
type State struct {
	// diagnostics are a map of relative path->diagnostics params
	diagnostics        map[string]*protocol.PublishDiagnosticsParams
	logs               []*protocol.LogMessageParams
	showDocument       []*protocol.ShowDocumentParams
	showMessage        []*protocol.ShowMessageParams
	showMessageRequest []*protocol.ShowMessageRequestParams

	registrations          []*protocol.RegistrationParams
	registeredCapabilities map[string]protocol.Registration
	unregistrations        []*protocol.UnregistrationParams

	// outstandingWork is a map of token->work summary. All tokens are assumed to
	// be string, though the spec allows for numeric tokens as well.
	work          map[protocol.ProgressToken]*workProgress
	startedWork   map[string]uint64 // title -> count of 'begin'
	completedWork map[string]uint64 // title -> count of 'end'
}

type workProgress struct {
	title, msg, endMsg string
	percent            float64
	complete           bool // seen 'end'
}

type awaitResult struct {
	verdict Verdict
	reason  string
}

// A condition is satisfied when its expectation is [Met] or [Unmeetable]. The
// result is sent on the verdict channel.
type condition struct {
	expectation Expectation
	verdict     chan awaitResult
}

func (a *Awaiter) onDiagnostics(_ context.Context, d *protocol.PublishDiagnosticsParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	pth := a.workdir.URIToPath(d.URI)
	a.state.diagnostics[pth] = d
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) onShowDocument(_ context.Context, params *protocol.ShowDocumentParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	// Update any outstanding listeners.
	for id, s := range a.docCollectors {
		a.docCollectors[id] = append(s, params)
	}

	a.state.showDocument = append(a.state.showDocument, params)
	a.checkConditionsLocked()
	return nil
}

// ListenToShownDocuments registers a listener to incoming showDocument
// notifications. Call the resulting func to deregister the listener and
// receive all notifications that have occurred since the listener was
// registered.
func (a *Awaiter) ListenToShownDocuments() func() []*protocol.ShowDocumentParams {
	id := nextAwaiterRegistration.Add(1)

	a.mu.Lock()
	defer a.mu.Unlock()

	if a.docCollectors == nil {
		a.docCollectors = make(map[uint64][]*protocol.ShowDocumentParams)
	}
	a.docCollectors[id] = nil

	return func() []*protocol.ShowDocumentParams {
		a.mu.Lock()
		defer a.mu.Unlock()
		params := a.docCollectors[id]
		delete(a.docCollectors, id)
		return params
	}
}

func (a *Awaiter) onShowMessage(_ context.Context, params *protocol.ShowMessageParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	// Update any outstanding listeners.
	for id, s := range a.messageCollectors {
		a.messageCollectors[id] = append(s, params)
	}

	a.state.showMessage = append(a.state.showMessage, params)
	a.checkConditionsLocked()
	return nil
}

// ListenToShownMessages registers a listener to incoming showMessage
// notifications. Call the resulting func to deregister the listener and
// receive all notifications that have occurred since the listener was
// registered.
//
// ListenToShownMessages should be called before the operation that
// generates the showMessage event to ensure that the event is
// reliably collected.
func (a *Awaiter) ListenToShownMessages() func() []*protocol.ShowMessageParams {
	id := nextAwaiterRegistration.Add(1)

	a.mu.Lock()
	defer a.mu.Unlock()

	if a.messageCollectors == nil {
		a.messageCollectors = make(map[uint64][]*protocol.ShowMessageParams)
	}
	a.messageCollectors[id] = nil

	return func() []*protocol.ShowMessageParams {
		a.mu.Lock()
		defer a.mu.Unlock()
		params := a.messageCollectors[id]
		delete(a.messageCollectors, id)
		return params
	}
}

func (a *Awaiter) onShowMessageRequest(_ context.Context, m *protocol.ShowMessageRequestParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.state.showMessageRequest = append(a.state.showMessageRequest, m)
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) onLogMessage(_ context.Context, m *protocol.LogMessageParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.state.logs = append(a.state.logs, m)
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) onWorkDoneProgressCreate(_ context.Context, m *protocol.WorkDoneProgressCreateParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.state.work[m.Token] = &workProgress{}
	return nil
}

func (a *Awaiter) onProgress(_ context.Context, m *protocol.ProgressParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()
	work, ok := a.state.work[m.Token]
	if !ok {
		panic(fmt.Sprintf("got progress report for unknown report %v: %v", m.Token, m))
	}
	v := m.Value.(map[string]any)
	switch kind := v["kind"]; kind {
	case "begin":
		work.title = v["title"].(string)
		a.state.startedWork[work.title]++
		if msg, ok := v["message"]; ok {
			work.msg = msg.(string)
		}
	case "report":
		if pct, ok := v["percentage"]; ok {
			work.percent = pct.(float64)
		}
		if msg, ok := v["message"]; ok {
			work.msg = msg.(string)
		}
	case "end":
		work.complete = true
		a.state.completedWork[work.title]++
		if msg, ok := v["message"]; ok {
			work.endMsg = msg.(string)
		}
	}
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) onRegisterCapability(_ context.Context, m *protocol.RegistrationParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.state.registrations = append(a.state.registrations, m)
	if a.state.registeredCapabilities == nil {
		a.state.registeredCapabilities = make(map[string]protocol.Registration)
	}
	for _, reg := range m.Registrations {
		a.state.registeredCapabilities[reg.Method] = reg
	}
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) onUnregisterCapability(_ context.Context, m *protocol.UnregistrationParams) error {
	a.mu.Lock()
	defer a.mu.Unlock()

	a.state.unregistrations = append(a.state.unregistrations, m)
	a.checkConditionsLocked()
	return nil
}

func (a *Awaiter) checkConditionsLocked() {
	for id, condition := range a.waiters {
		if v, why := condition.expectation.Check(a.state); v != Unmet {
			delete(a.waiters, id)
			condition.verdict <- awaitResult{v, why}
		}
	}
}

// Await blocks until the given expectations are all simultaneously met.
//
// Generally speaking Await should be avoided because it blocks indefinitely if
// gopls ends up in a state where the expectations are never going to be met.
// Use AfterChange or OnceMet instead, so that the runner knows when to stop
// waiting.
func (e *Env) Await(expectations ...Expectation) {
	e.TB.Helper()
	if err := e.Awaiter.Await(e.Ctx, AllOf(expectations...)); err != nil {
		e.TB.Fatal(err)
	}
}

// OnceMet blocks until the precondition is met by the state or becomes
// unmeetable. If it was met, OnceMet checks that the state meets all
// expectations in mustMeets.
func (e *Env) OnceMet(pre Expectation, mustMeets ...Expectation) {
	e.TB.Helper()
	e.Await(OnceMet(pre, AllOf(mustMeets...)))
}

// Await waits for all expectations to simultaneously be met. It should only be
// called from the main test goroutine.
func (a *Awaiter) Await(ctx context.Context, expectation Expectation) error {
	a.mu.Lock()
	// Before adding the waiter, we check if the condition is currently met or
	// failed to avoid a race where the condition was realized before Await was
	// called.
	switch verdict, why := expectation.Check(a.state); verdict {
	case Met:
		a.mu.Unlock()
		return nil
	case Unmeetable:
		err := fmt.Errorf("unmeetable expectation:\n%s\nreason:\n%s", indent(expectation.Description), indent(why))
		a.mu.Unlock()
		return err
	}
	cond := &condition{
		expectation: expectation,
		verdict:     make(chan awaitResult),
	}
	a.waiters[nextAwaiterRegistration.Add(1)] = cond
	a.mu.Unlock()

	var err error
	select {
	case <-ctx.Done():
		err = ctx.Err()
	case res := <-cond.verdict:
		if res.verdict != Met {
			err = fmt.Errorf("the following condition is %s:\n%s\nreason:\n%s",
				res.verdict, indent(expectation.Description), indent(res.reason))
		}
	}
	return err
}

// indent indents all lines of msg, including the first.
func indent(msg string) string {
	const prefix = "  "
	return prefix + strings.ReplaceAll(msg, "\n", "\n"+prefix)
}

// CleanModCache cleans the specified GOMODCACHE.
//
// TODO(golang/go#74595): this is only necessary as the module cache cleaning of the
// sandbox does not respect GOMODCACHE set via EnvVars. We should fix this, but
// that is probably part of a larger refactoring of the sandbox that I'm not
// inclined to undertake. --rfindley.
//
// (For similar problems caused by the same bug, see Test_issue38211; see also
// comment in Sandbox.Env.)
func CleanModCache(t *testing.T, modcache string) {
	cmd := exec.Command("go", "clean", "-modcache")
	cmd.Env = append(os.Environ(), "GOMODCACHE="+modcache, "GOTOOLCHAIN=local")
	if output, err := cmd.CombinedOutput(); err != nil {
		t.Errorf("cleaning modcache: %v\noutput:\n%s", err, string(output))
	}
}

// CodeActionByKind returns the first action of (exactly) the specified kind, or an error.
func CodeActionByKind(actions []protocol.CodeAction, kind protocol.CodeActionKind) (*protocol.CodeAction, error) {
	for _, act := range actions {
		if act.Kind == kind {
			return &act, nil
		}
	}
	return nil, fmt.Errorf("can't find action with kind %s, only %#v", kind, actions)
}


================================================
FILE: gopls/internal/test/integration/env_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"context"
	"encoding/json"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

func TestProgressUpdating(t *testing.T) {
	a := &Awaiter{
		state: State{
			work:          make(map[protocol.ProgressToken]*workProgress),
			startedWork:   make(map[string]uint64),
			completedWork: make(map[string]uint64),
		},
	}
	ctx := context.Background()
	if err := a.onWorkDoneProgressCreate(ctx, &protocol.WorkDoneProgressCreateParams{
		Token: "foo",
	}); err != nil {
		t.Fatal(err)
	}
	if err := a.onWorkDoneProgressCreate(ctx, &protocol.WorkDoneProgressCreateParams{
		Token: "bar",
	}); err != nil {
		t.Fatal(err)
	}
	updates := []struct {
		token string
		value any
	}{
		{"foo", protocol.WorkDoneProgressBegin{Kind: "begin", Title: "foo work"}},
		{"bar", protocol.WorkDoneProgressBegin{Kind: "begin", Title: "bar work"}},
		{"foo", protocol.WorkDoneProgressEnd{Kind: "end"}},
		{"bar", protocol.WorkDoneProgressReport{Kind: "report", Percentage: varOf[uint32](42)}},
	}
	for _, update := range updates {
		params := &protocol.ProgressParams{
			Token: update.token,
			Value: update.value,
		}
		data, err := json.Marshal(params)
		if err != nil {
			t.Fatal(err)
		}
		var unmarshaled protocol.ProgressParams
		if err := json.Unmarshal(data, &unmarshaled); err != nil {
			t.Fatal(err)
		}
		if err := a.onProgress(ctx, &unmarshaled); err != nil {
			t.Fatal(err)
		}
	}
	if got, want := a.state.completedWork["foo work"], uint64(1); got != want {
		t.Errorf(`completedWork["foo work"] = %d, want %d`, got, want)
	}
	got := *a.state.work["bar"]
	want := workProgress{title: "bar work", percent: 42}
	if got != want {
		t.Errorf("work progress for \"bar\": %v, want %v", got, want)
	}
}

// varOf returns a new variable whose value is x.
func varOf[T any](x T) *T { return &x }


================================================
FILE: gopls/internal/test/integration/expectation.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"bytes"
	"fmt"
	"maps"
	"regexp"
	"slices"
	"strings"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/util/constraints"
)

var (
	// InitialWorkspaceLoad is an expectation that the workspace initial load has
	// completed. It is verified via workdone reporting.
	InitialWorkspaceLoad = CompletedWork(server.DiagnosticWorkTitle(server.FromInitialWorkspaceLoad), 1, false)
)

// A Verdict is the result of checking an expectation against the current
// editor state.
type Verdict int

// Order matters for the following constants: verdicts are sorted in order of
// decisiveness.
const (
	// Met indicates that an expectation is satisfied by the current state.
	Met Verdict = iota
	// Unmet indicates that an expectation is not currently met, but could be met
	// in the future.
	Unmet
	// Unmeetable indicates that an expectation cannot be satisfied in the
	// future.
	Unmeetable
)

func (v Verdict) String() string {
	switch v {
	case Met:
		return "Met"
	case Unmet:
		return "Unmet"
	case Unmeetable:
		return "Unmeetable"
	}
	return fmt.Sprintf("unrecognized verdict %d", v)
}

// An Expectation is an expected property of the state of the LSP client.
// The Check function reports whether the property is met.
//
// Expectations are combinators. By composing them, tests may express
// complex expectations in terms of simpler ones.
type Expectation struct {
	// Check returns the verdict of this expectation for the given state.
	// If the vertict is not [Met], the second result should return a reason
	// that the verdict is not (yet) met.
	Check func(State) (Verdict, string)

	// Description holds a noun-phrase identifying what the expectation checks.
	//
	// TODO(rfindley): revisit existing descriptions to ensure they compose nicely.
	Description string
}

// OnceMet returns an Expectation that, once the precondition is met, asserts
// that mustMeet is met.
func OnceMet(pre, post Expectation) Expectation {
	check := func(s State) (Verdict, string) {
		switch v, why := pre.Check(s); v {
		case Unmeetable, Unmet:
			return v, fmt.Sprintf("precondition is %s: %s", v, why)
		case Met:
			v, why := post.Check(s)
			if v != Met {
				return Unmeetable, fmt.Sprintf("postcondition is not met:\n%s", indent(why))
			}
			return Met, ""
		default:
			panic(fmt.Sprintf("unknown precondition verdict %s", v))
		}
	}
	desc := fmt.Sprintf("once the following is met:\n%s\nmust have:\n%s",
		indent(pre.Description), indent(post.Description))
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// Not inverts the sense of an expectation: a met expectation is unmet, and an
// unmet expectation is met.
func Not(e Expectation) Expectation {
	check := func(s State) (Verdict, string) {
		switch v, _ := e.Check(s); v {
		case Met:
			return Unmet, "condition unexpectedly satisfied"
		case Unmet, Unmeetable:
			return Met, ""
		default:
			panic(fmt.Sprintf("unexpected verdict %v", v))
		}
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("not: %s", e.Description),
	}
}

// AnyOf returns an expectation that is satisfied when any of the given
// expectations is met.
func AnyOf(anyOf ...Expectation) Expectation {
	if len(anyOf) == 1 {
		return anyOf[0] // avoid unnecessary boilerplate
	}
	check := func(s State) (Verdict, string) {
		for _, e := range anyOf {
			verdict, _ := e.Check(s)
			if verdict == Met {
				return Met, ""
			}
		}
		return Unmet, "none of the expectations were met"
	}
	description := describeExpectations(anyOf...)
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("any of:\n%s", description),
	}
}

// AllOf expects that all given expectations are met.
func AllOf(allOf ...Expectation) Expectation {
	if len(allOf) == 1 {
		return allOf[0] // avoid unnecessary boilerplate
	}
	check := func(s State) (Verdict, string) {
		var (
			verdict = Met
			reason  string
		)
		for _, e := range allOf {
			v, why := e.Check(s)
			if v > verdict {
				verdict = v
				reason = why
			}
		}
		return verdict, reason
	}
	desc := describeExpectations(allOf...)
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("all of:\n%s", indent(desc)),
	}
}

func describeExpectations(expectations ...Expectation) string {
	var descriptions []string
	for _, e := range expectations {
		descriptions = append(descriptions, e.Description)
	}
	return strings.Join(descriptions, "\n")
}

// ReadDiagnostics is an Expectation that stores the current diagnostics for
// fileName in into, whenever it is evaluated.
//
// It can be used in combination with OnceMet or AfterChange to capture the
// state of diagnostics when other expectations are satisfied.
func ReadDiagnostics(fileName string, into *protocol.PublishDiagnosticsParams) Expectation {
	check := func(s State) (Verdict, string) {
		diags, ok := s.diagnostics[fileName]
		if !ok {
			return Unmeetable, fmt.Sprintf("no diagnostics for %q", fileName)
		}
		*into = *diags
		return Met, ""
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("read diagnostics for %q", fileName),
	}
}

// ReadAllDiagnostics is an expectation that stores all published diagnostics
// into the provided map, whenever it is evaluated.
//
// It can be used in combination with OnceMet or AfterChange to capture the
// state of diagnostics when other expectations are satisfied.
func ReadAllDiagnostics(into *map[string]*protocol.PublishDiagnosticsParams) Expectation {
	check := func(s State) (Verdict, string) {
		allDiags := maps.Clone(s.diagnostics)
		*into = allDiags
		return Met, ""
	}
	return Expectation{
		Check:       check,
		Description: "read all diagnostics",
	}
}

// ShownDocument asserts that the client has received a
// ShowDocumentRequest for the given URI.
func ShownDocument(uri protocol.URI) Expectation {
	check := func(s State) (Verdict, string) {
		for _, params := range s.showDocument {
			if params.URI == uri {
				return Met, ""
			}
		}
		return Unmet, fmt.Sprintf("no ShowDocumentRequest received for %s", uri)
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("received window/showDocument for URI %s", uri),
	}
}

// ShownDocuments is an expectation that appends each showDocument
// request into the provided slice, whenever it is evaluated.
//
// It can be used in combination with OnceMet or AfterChange to
// capture the set of showDocument requests when other expectations
// are satisfied.
func ShownDocuments(into *[]*protocol.ShowDocumentParams) Expectation {
	check := func(s State) (Verdict, string) {
		*into = append(*into, s.showDocument...)
		return Met, ""
	}
	return Expectation{
		Check:       check,
		Description: "read shown documents",
	}
}

// NoShownMessage asserts that the editor has not received a ShowMessage.
func NoShownMessage(containing string) Expectation {
	check := func(s State) (Verdict, string) {
		for _, m := range s.showMessage {
			if strings.Contains(m.Message, containing) {
				// Format the message (which may contain newlines) as a block quote.
				msg := fmt.Sprintf("\"\"\"\n%s\n\"\"\"", strings.TrimSpace(m.Message))
				return Unmeetable, fmt.Sprintf("observed the following message:\n%s", indent(msg))
			}
		}
		return Met, ""
	}
	var desc string
	if containing != "" {
		desc = fmt.Sprintf("received no ShowMessage containing %q", containing)
	} else {
		desc = "received no ShowMessage requests"
	}
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// ShownMessage asserts that the editor has received a ShowMessageRequest
// containing the given substring.
func ShownMessage(containing string) Expectation {
	check := func(s State) (Verdict, string) {
		for _, m := range s.showMessage {
			if strings.Contains(m.Message, containing) {
				return Met, ""
			}
		}
		return Unmet, fmt.Sprintf("no ShowMessage containing %q", containing)
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("received window/showMessage containing %q", containing),
	}
}

// ShownMessageRequest asserts that the editor has received a
// ShowMessageRequest with message matching the given regular expression.
func ShownMessageRequest(matchingRegexp string) Expectation {
	msgRE := regexp.MustCompile(matchingRegexp)
	check := func(s State) (Verdict, string) {
		if len(s.showMessageRequest) == 0 {
			return Unmet, "no ShowMessageRequest have been received"
		}
		for _, m := range s.showMessageRequest {
			if msgRE.MatchString(m.Message) {
				return Met, ""
			}
		}
		return Unmet, fmt.Sprintf("no ShowMessageRequest (out of %d) match %q", len(s.showMessageRequest), matchingRegexp)
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("ShowMessageRequest matching %q", matchingRegexp),
	}
}

// DoneDiagnosingChanges expects that diagnostics are complete from common
// change notifications: didOpen, didChange, didSave, didChangeWatchedFiles,
// and didClose.
//
// This can be used when multiple notifications may have been sent, such as
// when a didChange is immediately followed by a didSave. It is insufficient to
// simply await NoOutstandingWork, because the LSP client has no control over
// when the server starts processing a notification. Therefore, we must keep
// track of
func (e *Env) DoneDiagnosingChanges() Expectation {
	stats := e.Editor.Stats()
	statsBySource := map[server.ModificationSource]uint64{
		server.FromDidOpen:                stats.DidOpen,
		server.FromDidChange:              stats.DidChange,
		server.FromDidSave:                stats.DidSave,
		server.FromDidChangeWatchedFiles:  stats.DidChangeWatchedFiles,
		server.FromDidClose:               stats.DidClose,
		server.FromDidChangeConfiguration: stats.DidChangeConfiguration,
	}

	var expected []server.ModificationSource
	for k, v := range statsBySource {
		if v > 0 {
			expected = append(expected, k)
		}
	}

	// Sort for stability.
	slices.Sort(expected)

	var all []Expectation
	for _, source := range expected {
		all = append(all, CompletedWork(server.DiagnosticWorkTitle(source), statsBySource[source], true))
	}

	return AllOf(all...)
}

// AfterChange expects that the given expectations will be met after all
// state-changing notifications have been processed by the server.
// Specifically, it awaits the awaits completion of the process of diagnosis
// after the following notifications, before checking the given expectations:
//   - textDocument/didOpen
//   - textDocument/didChange
//   - textDocument/didSave
//   - textDocument/didClose
//   - workspace/didChangeWatchedFiles
//   - workspace/didChangeConfiguration
func (e *Env) AfterChange(expectations ...Expectation) {
	e.TB.Helper()
	e.OnceMet(
		e.DoneDiagnosingChanges(),
		expectations...,
	)
}

// DoneWithOpen expects all didOpen notifications currently sent by the editor
// to be completely processed.
func (e *Env) DoneWithOpen() Expectation {
	opens := e.Editor.Stats().DidOpen
	return CompletedWork(server.DiagnosticWorkTitle(server.FromDidOpen), opens, true)
}

// StartedChange expects that the server has at least started processing all
// didChange notifications sent from the client.
func (e *Env) StartedChange() Expectation {
	changes := e.Editor.Stats().DidChange
	return StartedWork(server.DiagnosticWorkTitle(server.FromDidChange), changes)
}

// DoneWithChange expects all didChange notifications currently sent by the
// editor to be completely processed.
func (e *Env) DoneWithChange() Expectation {
	changes := e.Editor.Stats().DidChange
	return CompletedWork(server.DiagnosticWorkTitle(server.FromDidChange), changes, true)
}

// DoneWithSave expects all didSave notifications currently sent by the editor
// to be completely processed.
func (e *Env) DoneWithSave() Expectation {
	saves := e.Editor.Stats().DidSave
	return CompletedWork(server.DiagnosticWorkTitle(server.FromDidSave), saves, true)
}

// StartedChangeWatchedFiles expects that the server has at least started
// processing all didChangeWatchedFiles notifications sent from the client.
func (e *Env) StartedChangeWatchedFiles() Expectation {
	changes := e.Editor.Stats().DidChangeWatchedFiles
	return StartedWork(server.DiagnosticWorkTitle(server.FromDidChangeWatchedFiles), changes)
}

// DoneWithChangeWatchedFiles expects all didChangeWatchedFiles notifications
// currently sent by the editor to be completely processed.
func (e *Env) DoneWithChangeWatchedFiles() Expectation {
	changes := e.Editor.Stats().DidChangeWatchedFiles
	return CompletedWork(server.DiagnosticWorkTitle(server.FromDidChangeWatchedFiles), changes, true)
}

// DoneWithClose expects all didClose notifications currently sent by the
// editor to be completely processed.
func (e *Env) DoneWithClose() Expectation {
	changes := e.Editor.Stats().DidClose
	return CompletedWork(server.DiagnosticWorkTitle(server.FromDidClose), changes, true)
}

// StartedWork expect a work item to have been started >= atLeast times.
//
// See CompletedWork.
func StartedWork(title string, atLeast uint64) Expectation {
	check := func(s State) (Verdict, string) {
		started := s.startedWork[title]
		if started >= atLeast {
			return Met, ""
		}
		return Unmet, fmt.Sprintf("started work %d %s", started, pluralize("time", started))
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("started work %q at least %d %s", title, atLeast, pluralize("time", atLeast)),
	}
}

// CompletedWork expects a work item to have been completed >= atLeast times.
//
// Since the Progress API doesn't include any hidden metadata, we must use the
// progress notification title to identify the work we expect to be completed.
func CompletedWork(title string, count uint64, atLeast bool) Expectation {
	check := func(s State) (Verdict, string) {
		completed := s.completedWork[title]
		if completed == count || atLeast && completed > count {
			return Met, ""
		}
		return Unmet, fmt.Sprintf("completed %d %s", completed, pluralize("time", completed))
	}
	desc := fmt.Sprintf("completed work %q %v %s", title, count, pluralize("time", count))
	if atLeast {
		desc = fmt.Sprintf("completed work %q at least %d %s", title, count, pluralize("time", count))
	}
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// pluralize adds an 's' suffix to name if n > 1.
func pluralize[T constraints.Integer](name string, n T) string {
	if n > 1 {
		return name + "s"
	}
	return name
}

type WorkStatus struct {
	// Last seen message from either `begin` or `report` progress.
	Msg string
	// Message sent with `end` progress message.
	EndMsg string
}

// CompletedProgressToken expects that workDone progress is complete for the given
// progress token. When non-nil WorkStatus is provided, it will be filled
// when the expectation is met.
//
// If the token is not a progress token that the client has seen, this
// expectation is Unmeetable.
func CompletedProgressToken(token protocol.ProgressToken, into *WorkStatus) Expectation {
	check := func(s State) (Verdict, string) {
		work, ok := s.work[token]
		if !ok {
			return Unmeetable, "no matching work items"
		}
		if work.complete {
			if into != nil {
				into.Msg = work.msg
				into.EndMsg = work.endMsg
			}
			return Met, ""
		}
		return Unmet, fmt.Sprintf("work is not complete; last message: %q", work.msg)
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("completed work for token %v", token),
	}
}

// CompletedProgress expects that there is exactly one workDone progress with
// the given title, and is satisfied when that progress completes. If it is
// met, the corresponding status is written to the into argument.
//
// TODO(rfindley): refactor to eliminate the redundancy with CompletedWork.
// This expectation is a vestige of older workarounds for asynchronous command
// execution.
func CompletedProgress(title string, into *WorkStatus) Expectation {
	check := func(s State) (Verdict, string) {
		var work *workProgress
		for _, w := range s.work {
			if w.title == title {
				if work != nil {
					return Unmeetable, "multiple matching work items"
				}
				work = w
			}
		}
		if work == nil {
			return Unmeetable, "no matching work items"
		}
		if work.complete {
			if into != nil {
				into.Msg = work.msg
				into.EndMsg = work.endMsg
			}
			return Met, ""
		}
		return Unmet, fmt.Sprintf("work is not complete; last message: %q", work.msg)
	}
	desc := fmt.Sprintf("exactly 1 completed workDoneProgress with title %v", title)
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// OutstandingWork expects a work item to be outstanding. The given title must
// be an exact match, whereas the given msg must only be contained in the work
// item's message.
func OutstandingWork(title, msg string) Expectation {
	check := func(s State) (Verdict, string) {
		for _, work := range s.work {
			if work.complete {
				continue
			}
			if work.title == title && strings.Contains(work.msg, msg) {
				return Met, ""
			}
		}
		return Unmet, "no matching work"
	}
	return Expectation{
		Check:       check,
		Description: fmt.Sprintf("outstanding work: %q containing %q", title, msg),
	}
}

// NoOutstandingWork asserts that there is no work initiated using the LSP
// $/progress API that has not completed.
//
// If non-nil, the ignore func is used to ignore certain work items for the
// purpose of this check.
//
// TODO(rfindley): consider refactoring to treat outstanding work the same way
// we treat diagnostics: with an algebra of filters.
func NoOutstandingWork(ignore func(title, msg string) bool) Expectation {
	check := func(s State) (Verdict, string) {
		for _, w := range s.work {
			if w.complete {
				continue
			}
			if w.title == "" {
				// A token that has been created but not yet used.
				//
				// TODO(rfindley): this should be separated in the data model: until
				// the "begin" notification, work should not be in progress.
				continue
			}
			if ignore != nil && ignore(w.title, w.msg) {
				continue
			}
			return Unmet, fmt.Sprintf("found outstanding work %q: %q", w.title, w.msg)
		}
		return Met, ""
	}
	return Expectation{
		Check:       check,
		Description: "no outstanding work",
	}
}

// IgnoreTelemetryPromptWork may be used in conjunction with NoOutStandingWork
// to ignore the telemetry prompt.
func IgnoreTelemetryPromptWork(title, msg string) bool {
	return title == server.TelemetryPromptWorkTitle
}

// NoErrorLogs asserts that the client has not received any log messages of
// error severity.
func NoErrorLogs() Expectation {
	return NoLogMatching(protocol.Error, "")
}

// LogMatching asserts that the client has received a log message
// of type typ matching the regexp re a certain number of times.
//
// The count argument specifies the expected number of matching logs. If
// atLeast is set, this is a lower bound, otherwise there must be exactly count
// matching logs.
//
// Logs are asynchronous to other LSP messages, so this expectation should not
// be used with combinators such as OnceMet or AfterChange that assert on
// ordering with respect to other operations.
func LogMatching(typ protocol.MessageType, re string, count int, atLeast bool) Expectation {
	rec, err := regexp.Compile(re)
	if err != nil {
		panic(err)
	}
	check := func(state State) (Verdict, string) {
		var found int
		for _, msg := range state.logs {
			if msg.Type == typ && rec.Match([]byte(msg.Message)) {
				found++
			}
		}
		// Check for an exact or "at least" match.
		if found == count || (found >= count && atLeast) {
			return Met, ""
		}
		// If we require an exact count, and have received more than expected, the
		// expectation can never be met.
		verdict := Unmet
		if found > count && !atLeast {
			verdict = Unmeetable
		}
		return verdict, fmt.Sprintf("found %d matching logs", found)
	}
	desc := fmt.Sprintf("log message matching %q expected %v times", re, count)
	if atLeast {
		desc = fmt.Sprintf("log message matching %q expected at least %v times", re, count)
	}
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// NoLogMatching asserts that the client has not received a log message
// of type typ matching the regexp re. If re is an empty string, any log
// message is considered a match.
func NoLogMatching(typ protocol.MessageType, re string) Expectation {
	var r *regexp.Regexp
	if re != "" {
		var err error
		r, err = regexp.Compile(re)
		if err != nil {
			panic(err)
		}
	}
	check := func(state State) (Verdict, string) {
		for _, msg := range state.logs {
			if msg.Type != typ {
				continue
			}
			if r == nil || r.Match([]byte(msg.Message)) {
				return Unmeetable, fmt.Sprintf("found matching log %q", msg.Message)
			}
		}
		return Met, ""
	}
	desc := fmt.Sprintf("no %s log messages", typ)
	if re != "" {
		desc += fmt.Sprintf(" matching %q", re)
	}
	return Expectation{
		Check:       check,
		Description: desc,
	}
}

// FileWatchMatching expects that a file registration matches re.
func FileWatchMatching(re string) Expectation {
	return Expectation{
		Check:       checkFileWatch(re, Met, Unmet),
		Description: fmt.Sprintf("file watch matching %q", re),
	}
}

// NoFileWatchMatching expects that no file registration matches re.
func NoFileWatchMatching(re string) Expectation {
	return Expectation{
		Check:       checkFileWatch(re, Unmet, Met),
		Description: fmt.Sprintf("no file watch matching %q", re),
	}
}

func checkFileWatch(re string, onMatch, onNoMatch Verdict) func(State) (Verdict, string) {
	rec := regexp.MustCompile(re)
	return func(s State) (Verdict, string) {
		r := s.registeredCapabilities["workspace/didChangeWatchedFiles"]
		watchers := jsonProperty(r.RegisterOptions, "watchers").([]any)
		for _, watcher := range watchers {
			pattern := jsonProperty(watcher, "globPattern").(string)
			if rec.MatchString(pattern) {
				return onMatch, fmt.Sprintf("matches watcher pattern %q", pattern)
			}
		}
		return onNoMatch, "no matching watchers"
	}
}

// jsonProperty extracts a value from a path of JSON property names, assuming
// the default encoding/json unmarshaling to the empty interface (i.e.: that
// JSON objects are unmarshalled as map[string]interface{})
//
// For example, if obj is unmarshalled from the following json:
//
//	{
//		"foo": { "bar": 3 }
//	}
//
// Then jsonProperty(obj, "foo", "bar") will be 3.
func jsonProperty(obj any, path ...string) any {
	if len(path) == 0 || obj == nil {
		return obj
	}
	m := obj.(map[string]any)
	return jsonProperty(m[path[0]], path[1:]...)
}

func formatDiagnostic(d protocol.Diagnostic) string {
	return fmt.Sprintf("%d:%d [%s]: %s\n", d.Range.Start.Line, d.Range.Start.Character, d.Source, d.Message)
}

// Diagnostics asserts that there is at least one diagnostic matching the given
// filters.
func Diagnostics(filters ...DiagnosticFilter) Expectation {
	check := func(s State) (Verdict, string) {
		diags := flattenDiagnostics(s)
		for _, filter := range filters {
			var filtered []flatDiagnostic
			for _, d := range diags {
				if filter.check(d.name, d.diag) {
					filtered = append(filtered, d)
				}
			}
			if len(filtered) == 0 {
				// Reprinting the description of the filters is too verbose.
				//
				// We can probably do better here, but for now just format the
				// diagnostics.
				var b bytes.Buffer
				for name, params := range s.diagnostics {
					fmt.Fprintf(&b, "\t%s (version %d):\n", name, params.Version)
					for _, d := range params.Diagnostics {
						fmt.Fprintf(&b, "\t\t%s", formatDiagnostic(d))
					}
				}
				return Unmet, fmt.Sprintf("diagnostics:\n%s", b.String())
			}
			diags = filtered
		}
		return Met, ""
	}
	var descs []string
	for _, filter := range filters {
		descs = append(descs, filter.desc)
	}
	return Expectation{
		Check:       check,
		Description: "any diagnostics " + strings.Join(descs, ", "),
	}
}

// NoDiagnostics asserts that there are no diagnostics matching the given
// filters. Notably, if no filters are supplied this assertion checks that
// there are no diagnostics at all, for any file.
func NoDiagnostics(filters ...DiagnosticFilter) Expectation {
	check := func(s State) (Verdict, string) {
		diags := flattenDiagnostics(s)
		for _, filter := range filters {
			var filtered []flatDiagnostic
			for _, d := range diags {
				if filter.check(d.name, d.diag) {
					filtered = append(filtered, d)
				}
			}
			diags = filtered
		}
		if len(diags) > 0 {
			d := diags[0]
			why := fmt.Sprintf("have diagnostic: %s: %v", d.name, formatDiagnostic(d.diag))
			return Unmet, why
		}
		return Met, ""
	}
	var descs []string
	for _, filter := range filters {
		descs = append(descs, filter.desc)
	}
	return Expectation{
		Check:       check,
		Description: "no diagnostics " + strings.Join(descs, ", "),
	}
}

type flatDiagnostic struct {
	name string
	diag protocol.Diagnostic
}

func flattenDiagnostics(state State) []flatDiagnostic {
	var result []flatDiagnostic
	for name, diags := range state.diagnostics {
		for _, diag := range diags.Diagnostics {
			result = append(result, flatDiagnostic{name, diag})
		}
	}
	return result
}

// -- Diagnostic filters --

// A DiagnosticFilter filters the set of diagnostics, for assertion with
// Diagnostics or NoDiagnostics.
type DiagnosticFilter struct {
	desc  string
	check func(name string, _ protocol.Diagnostic) bool
}

// ForFile filters to diagnostics matching the sandbox-relative file name.
func ForFile(name string) DiagnosticFilter {
	return DiagnosticFilter{
		desc: fmt.Sprintf("for file %q", name),
		check: func(diagName string, _ protocol.Diagnostic) bool {
			return diagName == name
		},
	}
}

// FromSource filters to diagnostics matching the given diagnostics source.
func FromSource(source string) DiagnosticFilter {
	return DiagnosticFilter{
		desc: fmt.Sprintf("with source %q", source),
		check: func(_ string, d protocol.Diagnostic) bool {
			return d.Source == source
		},
	}
}

// AtRegexp filters to diagnostics in the file with sandbox-relative path name,
// at the first position matching the given regexp pattern.
//
// TODO(rfindley): pass in the editor to expectations, so that they may depend
// on editor state and AtRegexp can be a function rather than a method.
func (e *Env) AtRegexp(name, pattern string) DiagnosticFilter {
	loc := e.RegexpSearch(name, pattern)
	return DiagnosticFilter{
		desc: fmt.Sprintf("at the first position (%v) matching %#q in %q", loc.Range.Start, pattern, name),
		check: func(diagName string, d protocol.Diagnostic) bool {
			return diagName == name && d.Range.Start == loc.Range.Start
		},
	}
}

// AtPosition filters to diagnostics at location name:line:character, for a
// sandbox-relative path name.
//
// Line and character are 0-based, and character measures UTF-16 codes.
//
// Note: prefer the more readable AtRegexp.
func AtPosition(name string, line, character uint32) DiagnosticFilter {
	pos := protocol.Position{Line: line, Character: character}
	return DiagnosticFilter{
		desc: fmt.Sprintf("at %s:%d:%d", name, line, character),
		check: func(diagName string, d protocol.Diagnostic) bool {
			return diagName == name && d.Range.Start == pos
		},
	}
}

// WithMessage filters to diagnostics whose message contains the given
// substring.
func WithMessage(substring string) DiagnosticFilter {
	return DiagnosticFilter{
		desc: fmt.Sprintf("with message containing %q", substring),
		check: func(_ string, d protocol.Diagnostic) bool {
			return strings.Contains(d.Message, substring)
		},
	}
}

// WithSeverityTags filters to diagnostics whose severity and tags match
// the given expectation.
func WithSeverityTags(diagName string, severity protocol.DiagnosticSeverity, tags []protocol.DiagnosticTag) DiagnosticFilter {
	return DiagnosticFilter{
		desc: fmt.Sprintf("with diagnostic %q with severity %q and tag %#q", diagName, severity, tags),
		check: func(_ string, d protocol.Diagnostic) bool {
			return d.Source == diagName && d.Severity == severity && cmp.Equal(d.Tags, tags)
		},
	}
}


================================================
FILE: gopls/internal/test/integration/fake/client.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"context"
	"encoding/json"
	"fmt"
	"path"
	"path/filepath"
	"sync/atomic"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake/glob"
)

// ClientHooks are a set of optional hooks called during handling of
// the corresponding client method (see protocol.Client for the
// LSP server-to-client RPCs) in order to make test expectations
// awaitable.
type ClientHooks struct {
	OnLogMessage             func(context.Context, *protocol.LogMessageParams) error
	OnDiagnostics            func(context.Context, *protocol.PublishDiagnosticsParams) error
	OnWorkDoneProgressCreate func(context.Context, *protocol.WorkDoneProgressCreateParams) error
	OnProgress               func(context.Context, *protocol.ProgressParams) error
	OnShowDocument           func(context.Context, *protocol.ShowDocumentParams) error
	OnShowMessage            func(context.Context, *protocol.ShowMessageParams) error
	OnShowMessageRequest     func(context.Context, *protocol.ShowMessageRequestParams) error
	OnRegisterCapability     func(context.Context, *protocol.RegistrationParams) error
	OnUnregisterCapability   func(context.Context, *protocol.UnregistrationParams) error
}

// Client is an implementation of the [protocol.Client] interface
// based on the test's fake [Editor]. It mostly delegates
// functionality to hooks that can be configured by tests.
type Client struct {
	editor      *Editor
	hooks       ClientHooks
	onApplyEdit atomic.Pointer[ApplyEditHandler] // hook for marker tests to intercept edits
}

type ApplyEditHandler = func(context.Context, *protocol.WorkspaceEdit) error

// SetApplyEditHandler sets the (non-nil) handler for ApplyEdit
// downcalls, and returns a function to restore the previous one.
// Use it around client-to-server RPCs to capture the edits.
// The default handler is c.Editor.onApplyEdit
func (c *Client) SetApplyEditHandler(h ApplyEditHandler) func() {
	if h == nil {
		panic("h is nil")
	}
	prev := c.onApplyEdit.Swap(&h)
	return func() {
		if c.onApplyEdit.Swap(prev) != &h {
			panic("improper nesting of SetApplyEditHandler, restore")
		}
	}
}

func (c *Client) CodeLensRefresh(context.Context) error { return nil }

func (c *Client) InlayHintRefresh(context.Context) error { return nil }

func (c *Client) DiagnosticRefresh(context.Context) error { return nil }

func (c *Client) FoldingRangeRefresh(context.Context) error { return nil }

func (c *Client) InlineValueRefresh(context.Context) error { return nil }

func (c *Client) SemanticTokensRefresh(context.Context) error { return nil }

func (c *Client) LogTrace(context.Context, *protocol.LogTraceParams) error { return nil }

func (c *Client) TextDocumentContentRefresh(context.Context, *protocol.TextDocumentContentRefreshParams) error {
	return nil
}

func (c *Client) ShowMessage(ctx context.Context, params *protocol.ShowMessageParams) error {
	if c.hooks.OnShowMessage != nil {
		return c.hooks.OnShowMessage(ctx, params)
	}
	return nil
}

func (c *Client) ShowMessageRequest(ctx context.Context, params *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error) {
	if c.hooks.OnShowMessageRequest != nil {
		if err := c.hooks.OnShowMessageRequest(ctx, params); err != nil {
			return nil, err
		}
	}
	if c.editor.config.MessageResponder != nil {
		return c.editor.config.MessageResponder(params)
	}
	return nil, nil // don't choose, which is effectively dismissing the message
}

func (c *Client) LogMessage(ctx context.Context, params *protocol.LogMessageParams) error {
	if c.hooks.OnLogMessage != nil {
		return c.hooks.OnLogMessage(ctx, params)
	}
	return nil
}

func (c *Client) Event(ctx context.Context, event *any) error {
	return nil
}

func (c *Client) PublishDiagnostics(ctx context.Context, params *protocol.PublishDiagnosticsParams) error {
	if c.hooks.OnDiagnostics != nil {
		return c.hooks.OnDiagnostics(ctx, params)
	}
	return nil
}

func (c *Client) WorkspaceFolders(context.Context) ([]protocol.WorkspaceFolder, error) {
	return []protocol.WorkspaceFolder{}, nil
}

func (c *Client) Configuration(_ context.Context, p *protocol.ParamConfiguration) ([]any, error) {
	results := make([]any, len(p.Items))
	for i, item := range p.Items {
		if item.ScopeURI != nil && *item.ScopeURI == "" {
			return nil, fmt.Errorf(`malformed ScopeURI ""`)
		}
		if item.Section == "gopls" {
			config := c.editor.Config()
			results[i] = makeSettings(c.editor.sandbox, config, item.ScopeURI)
		}
	}
	return results, nil
}

func (c *Client) RegisterCapability(ctx context.Context, params *protocol.RegistrationParams) error {
	if c.hooks.OnRegisterCapability != nil {
		if err := c.hooks.OnRegisterCapability(ctx, params); err != nil {
			return err
		}
	}
	// Update file watching patterns.
	//
	// TODO(rfindley): We could verify more here, like verify that the
	// registration ID is distinct, and that the capability is not currently
	// registered.
	for _, registration := range params.Registrations {
		if registration.Method == "workspace/didChangeWatchedFiles" {
			// Marshal and unmarshal to interpret RegisterOptions as
			// DidChangeWatchedFilesRegistrationOptions.
			raw, err := json.Marshal(registration.RegisterOptions)
			if err != nil {
				return fmt.Errorf("marshaling registration options: %v", err)
			}
			var opts protocol.DidChangeWatchedFilesRegistrationOptions
			if err := json.Unmarshal(raw, &opts); err != nil {
				return fmt.Errorf("unmarshaling registration options: %v", err)
			}
			var globs []*glob.Glob
			for _, watcher := range opts.Watchers {
				var globPattern string
				switch pattern := watcher.GlobPattern.Value.(type) {
				case protocol.Pattern:
					globPattern = pattern
				case protocol.RelativePattern:
					globPattern = path.Join(filepath.ToSlash(pattern.BaseURI.Path()), pattern.Pattern)
				}
				// TODO(rfindley): honor the watch kind.
				g, err := glob.Parse(globPattern)
				if err != nil {
					return fmt.Errorf("error parsing glob pattern %q: %v", watcher.GlobPattern, err)
				}
				globs = append(globs, g)
			}
			c.editor.mu.Lock()
			c.editor.watchPatterns = globs
			c.editor.mu.Unlock()
		}
	}
	return nil
}

func (c *Client) UnregisterCapability(ctx context.Context, params *protocol.UnregistrationParams) error {
	if c.hooks.OnUnregisterCapability != nil {
		return c.hooks.OnUnregisterCapability(ctx, params)
	}
	return nil
}

func (c *Client) Progress(ctx context.Context, params *protocol.ProgressParams) error {
	if c.hooks.OnProgress != nil {
		return c.hooks.OnProgress(ctx, params)
	}
	return nil
}

func (c *Client) WorkDoneProgressCreate(ctx context.Context, params *protocol.WorkDoneProgressCreateParams) error {
	if c.hooks.OnWorkDoneProgressCreate != nil {
		return c.hooks.OnWorkDoneProgressCreate(ctx, params)
	}
	return nil
}

func (c *Client) ShowDocument(ctx context.Context, params *protocol.ShowDocumentParams) (*protocol.ShowDocumentResult, error) {
	if c.hooks.OnShowDocument != nil {
		if err := c.hooks.OnShowDocument(ctx, params); err != nil {
			return nil, err
		}
		return &protocol.ShowDocumentResult{Success: true}, nil
	}
	return nil, nil
}

func (c *Client) ApplyEdit(ctx context.Context, params *protocol.ApplyWorkspaceEditParams) (*protocol.ApplyWorkspaceEditResult, error) {
	if len(params.Edit.Changes) > 0 {
		return &protocol.ApplyWorkspaceEditResult{FailureReason: "Edit.Changes is unsupported"}, nil
	}
	onApplyEdit := c.editor.applyWorkspaceEdit
	if ptr := c.onApplyEdit.Load(); ptr != nil {
		onApplyEdit = *ptr
	}
	if err := onApplyEdit(ctx, &params.Edit); err != nil {
		return nil, err
	}
	return &protocol.ApplyWorkspaceEditResult{Applied: true}, nil
}


================================================
FILE: gopls/internal/test/integration/fake/doc.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fake provides a fake implementation of an LSP-enabled
// text editor, its LSP client plugin, and a Sandbox environment for
// use in integration tests.
//
// The Editor type provides a high level API for text editor operations
// (open/modify/save/close a buffer, jump to definition, etc.), and the Client
// type exposes an LSP client for the editor that can be connected to a
// language server. By default, the Editor and Client should be compliant with
// the LSP spec: their intended use is to verify server compliance with the
// spec in a variety of environment. Possible future enhancements of these
// types may allow them to misbehave in configurable ways, but that is not
// their primary use.
//
// The Sandbox type provides a facility for executing tests with a temporary
// directory, module proxy, and GOPATH.
package fake


================================================
FILE: gopls/internal/test/integration/fake/edit.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/diff"
)

// NewEdit creates an edit replacing all content between the 0-based
// (startLine, startColumn) and (endLine, endColumn) with text.
//
// Columns measure UTF-16 codes.
func NewEdit(startLine, startColumn, endLine, endColumn uint32, text string) protocol.TextEdit {
	return protocol.TextEdit{
		Range: protocol.Range{
			Start: protocol.Position{Line: startLine, Character: startColumn},
			End:   protocol.Position{Line: endLine, Character: endColumn},
		},
		NewText: text,
	}
}

// applyEdits applies the edits to a file with the specified lines,
// and returns a new slice containing the lines of the patched file.
// It is a wrapper around diff.Apply; see that function for preconditions.
func applyEdits(mapper *protocol.Mapper, edits []protocol.TextEdit, windowsLineEndings bool) ([]byte, error) {
	diffEdits, err := protocol.EditsToDiffEdits(mapper, edits)
	if err != nil {
		return nil, err
	}
	patched, err := diff.ApplyBytes(mapper.Content, diffEdits)
	if err != nil {
		return nil, err
	}
	if windowsLineEndings {
		patched = toWindowsLineEndings(patched)
	}
	return patched, nil
}


================================================
FILE: gopls/internal/test/integration/fake/edit_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

func TestApplyEdits(t *testing.T) {
	tests := []struct {
		label   string
		content string
		edits   []protocol.TextEdit
		want    string
		wantErr bool
	}{
		{
			label: "empty content",
		},
		{
			label:   "empty edit",
			content: "hello",
			edits:   []protocol.TextEdit{},
			want:    "hello",
		},
		{
			label:   "unicode edit",
			content: "hello, 日本語",
			edits: []protocol.TextEdit{
				NewEdit(0, 7, 0, 10, "world"),
			},
			want: "hello, world",
		},
		{
			label:   "range edit",
			content: "ABC\nDEF\nGHI\nJKL",
			edits: []protocol.TextEdit{
				NewEdit(1, 1, 2, 3, "12\n345"),
			},
			want: "ABC\nD12\n345\nJKL",
		},
		{
			label:   "regression test for issue #57627",
			content: "go 1.18\nuse moda/a",
			edits: []protocol.TextEdit{
				NewEdit(1, 0, 1, 0, "\n"),
				NewEdit(2, 0, 2, 0, "\n"),
			},
			want: "go 1.18\n\nuse moda/a\n",
		},
		{
			label:   "end before start",
			content: "ABC\nDEF\nGHI\nJKL",
			edits: []protocol.TextEdit{
				NewEdit(2, 3, 1, 1, "12\n345"),
			},
			wantErr: true,
		},
		{
			label:   "out of bounds line",
			content: "ABC\nDEF\nGHI\nJKL",
			edits: []protocol.TextEdit{
				NewEdit(1, 1, 4, 3, "12\n345"),
			},
			wantErr: true,
		},
		{
			label:   "out of bounds column",
			content: "ABC\nDEF\nGHI\nJKL",
			edits: []protocol.TextEdit{
				NewEdit(1, 4, 2, 3, "12\n345"),
			},
			wantErr: true,
		},
	}

	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			got, err := applyEdits(protocol.NewMapper("", []byte(test.content)), test.edits, false)
			if (err != nil) != test.wantErr {
				t.Errorf("got err %v, want error: %t", err, test.wantErr)
			}
			if err != nil {
				return
			}
			if got := string(got); got != test.want {
				t.Errorf("got %q, want %q", got, test.want)
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/fake/editor.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"maps"
	"math/rand/v2"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"slices"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration/fake/glob"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/pathutil"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/xcontext"
)

// Editor is a fake client editor.  It keeps track of client state and can be
// used for writing LSP tests.
type Editor struct {

	// Server, client, and sandbox are concurrency safe and written only
	// at construction time, so do not require synchronization.
	Server     protocol.Server
	cancelConn func()
	serverConn jsonrpc2.Conn
	client     *Client
	sandbox    *Sandbox

	// TODO(rfindley): buffers should be keyed by protocol.DocumentURI.
	mu                       sync.Mutex
	config                   EditorConfig      // editor configuration
	buffers                  map[string]buffer // open buffers (relative path -> buffer content)
	watchPatterns            []*glob.Glob      // glob patterns to watch
	suggestionUseReplaceMode bool

	// These fields are populated by Connect.
	serverCapabilities protocol.ServerCapabilities
	semTokOpts         protocol.SemanticTokensOptions

	// Call metrics for the purpose of expectations. This is done in an ad-hoc
	// manner for now. Perhaps in the future we should do something more
	// systematic. Guarded with a separate mutex as calls may need to be accessed
	// asynchronously via callbacks into the Editor.
	callsMu sync.Mutex
	calls   CallCounts
}

// CallCounts tracks the number of protocol notifications of different types.
type CallCounts struct {
	DidOpen, DidChange, DidSave, DidChangeWatchedFiles, DidClose, DidChangeConfiguration uint64
}

// buffer holds information about an open buffer in the editor.
type buffer struct {
	version int              // monotonic version; incremented on edits
	path    string           // relative path in the workspace
	mapper  *protocol.Mapper // buffer content
	dirty   bool             // if true, content is unsaved (TODO(rfindley): rename this field)
}

func (b buffer) text() string {
	return string(b.mapper.Content)
}

// EditorConfig configures the editor's LSP session. This is similar to
// golang.UserOptions, but we use a separate type here so that we expose only
// that configuration which we support.
//
// The zero value for EditorConfig is the default configuration.
type EditorConfig struct {
	// ClientName sets the clientInfo.name for the LSP session (in the initialize request).
	//
	// Since this can only be set during initialization, changing this field via
	// Editor.ChangeConfiguration has no effect.
	//
	// If empty, "fake.Editor" is used.
	ClientName string

	// Env holds environment variables to apply on top of the default editor
	// environment. When applying these variables, the special string
	// $SANDBOX_WORKDIR is replaced by the absolute path to the sandbox working
	// directory.
	Env map[string]string

	// WorkspaceFolders is the workspace folders to configure on the LSP server.
	// Each workspace folder is a file path relative to the sandbox workdir, or
	// a uri (used when testing behavior with virtual file system or non-'file'
	// scheme document uris).
	//
	// As special cases, if WorkspaceFolders is nil the editor defaults to
	// configuring a single workspace folder corresponding to the workdir root.
	// To explicitly send no workspace folders, use an empty (non-nil) slice.
	WorkspaceFolders []string

	// NoDefaultWorkspaceFiles is used to specify whether the fake editor
	// should give a default workspace folder when WorkspaceFolders is nil.
	// When it's true, the editor will pass original WorkspaceFolders as is to the LSP server.
	NoDefaultWorkspaceFiles bool

	// RelRootPath is the root path which will be converted to rootUri to configure on the LSP server.
	RelRootPath string

	// Whether to edit files with windows line endings.
	WindowsLineEndings bool

	// Map of language ID -> regexp to match, used to set the file type of new
	// buffers. Applied as an overlay on top of the following defaults:
	//  "go"     -> ".*\.go"
	//  "go.mod" -> "go\.mod"
	//  "go.sum" -> "go\.sum"
	//  "gotmpl" -> ".*tmpl"
	//  "go.s"   -> ".*\.s"
	FileAssociations map[protocol.LanguageKind]string

	// Settings holds user-provided configuration for the LSP server.
	Settings map[string]any

	// FolderSettings holds user-provided per-folder configuration, if any.
	//
	// It maps each folder (as a relative path to the sandbox workdir) to its
	// configuration mapping (like Settings).
	FolderSettings map[string]map[string]any

	// CapabilitiesJSON holds JSON client capabilities to overlay over the
	// editor's default client capabilities.
	//
	// Specifically, this JSON string will be unmarshalled into the editor's
	// client capabilities struct, before sending to the server.
	CapabilitiesJSON []byte

	// If non-nil, MessageResponder is used to respond to ShowMessageRequest
	// messages.
	MessageResponder func(params *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error)

	// MaxMessageDelay is used for fuzzing message delivery to reproduce test
	// flakes.
	MaxMessageDelay time.Duration
}

// NewEditor creates a new Editor.
func NewEditor(sandbox *Sandbox, config EditorConfig) *Editor {
	return &Editor{
		buffers: make(map[string]buffer),
		sandbox: sandbox,
		config:  config,
	}
}

// Connect configures the editor to communicate with an LSP server on conn. It
// is not concurrency safe, and should be called at most once, before using the
// editor.
//
// It returns the editor, so that it may be called as follows:
//
//	editor, err := NewEditor(s).Connect(ctx, conn, hooks)
func (e *Editor) Connect(ctx context.Context, connector servertest.Connector, hooks ClientHooks) (*Editor, error) {
	bgCtx, cancelConn := context.WithCancel(xcontext.Detach(ctx))
	conn := connector.Connect(bgCtx)
	e.cancelConn = cancelConn

	e.serverConn = conn
	e.Server = protocol.ServerDispatcher(conn)
	e.client = &Client{editor: e, hooks: hooks}
	handler := protocol.ClientHandler(e.client, jsonrpc2.MethodNotFound)
	if e.config.MaxMessageDelay > 0 {
		handler = DelayedHandler(e.config.MaxMessageDelay, handler)
	}
	conn.Go(bgCtx, protocol.Handlers(handler))

	if err := e.initialize(ctx); err != nil {
		return nil, err
	}
	e.sandbox.Workdir.AddWatcher(e.onFileChanges)
	return e, nil
}

// DelayedHandler waits [0, maxDelay) before handling each message.
func DelayedHandler(maxDelay time.Duration, handler jsonrpc2.Handler) jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
		delay := time.Duration(rand.Int64N(int64(maxDelay)))
		select {
		case <-ctx.Done():
		case <-time.After(delay):
		}
		return handler(ctx, reply, req)
	}
}

func (e *Editor) Stats() CallCounts {
	e.callsMu.Lock()
	defer e.callsMu.Unlock()
	return e.calls
}

// Shutdown issues the 'shutdown' LSP notification.
func (e *Editor) Shutdown(ctx context.Context) error {
	if e.Server != nil {
		if err := e.Server.Shutdown(ctx); err != nil {
			return fmt.Errorf("Shutdown: %w", err)
		}
	}
	return nil
}

// Exit issues the 'exit' LSP notification.
func (e *Editor) Exit(ctx context.Context) error {
	if e.Server != nil {
		// Not all LSP clients issue the exit RPC, but we do so here to ensure that
		// we gracefully handle it on multi-session servers.
		if err := e.Server.Exit(ctx); err != nil {
			return fmt.Errorf("Exit: %w", err)
		}
	}
	return nil
}

// Close disconnects the LSP client session.
// TODO(rfindley): rename to 'Disconnect'.
func (e *Editor) Close(ctx context.Context) error {
	if err := e.Shutdown(ctx); err != nil {
		return err
	}
	if err := e.Exit(ctx); err != nil {
		return err
	}
	defer func() {
		e.cancelConn()
	}()

	// called close on the editor should result in the connection closing
	select {
	case <-e.serverConn.Done():
		// connection closed itself
		return nil
	case <-ctx.Done():
		return fmt.Errorf("connection not closed: %w", ctx.Err())
	}
}

// Client returns the LSP client for this editor.
func (e *Editor) Client() *Client {
	return e.client
}

// makeSettings builds the settings map for use in LSP settings RPCs.
func makeSettings(sandbox *Sandbox, config EditorConfig, scopeURI *protocol.URI) map[string]any {
	env := make(map[string]string)
	maps.Copy(env, sandbox.GoEnv())
	maps.Copy(env, config.Env)
	for k, v := range env {
		v = strings.ReplaceAll(v, "$SANDBOX_WORKDIR", sandbox.Workdir.RootURI().Path())
		env[k] = v
	}

	settings := map[string]any{
		"env": env,

		// Use verbose progress reporting so that integration tests can assert on
		// asynchronous operations being completed (such as diagnosing a snapshot).
		"verboseWorkDoneProgress": true,

		// Set an unlimited completion budget, so that tests don't flake because
		// completions are too slow.
		"completionBudget": "0s",
	}

	for k, v := range config.Settings {
		if k == "env" {
			panic("must not provide env via the EditorConfig.Settings field: use the EditorConfig.Env field instead")
		}
		settings[k] = v
	}

	// If the server is requesting configuration for a specific scope, apply
	// settings for the nearest folder that has customized settings, if any.
	if scopeURI != nil {
		var (
			scopePath       = protocol.DocumentURI(*scopeURI).Path()
			closestDir      string         // longest dir with settings containing the scope, if any
			closestSettings map[string]any // settings for that dir, if any
		)
		for relPath, settings := range config.FolderSettings {
			dir := sandbox.Workdir.AbsPath(relPath)
			if strings.HasPrefix(scopePath+string(filepath.Separator), dir+string(filepath.Separator)) && len(dir) > len(closestDir) {
				closestDir = dir
				closestSettings = settings
			}
		}
		if closestSettings != nil {
			maps.Copy(settings, closestSettings)
		}
	}

	return settings
}

func (e *Editor) initialize(ctx context.Context) error {
	config := e.Config()

	clientName := config.ClientName
	if clientName == "" {
		clientName = "fake.Editor"
	}

	params := &protocol.ParamInitialize{}
	params.ClientInfo = &protocol.ClientInfo{
		Name:    clientName,
		Version: "v1.0.0",
	}
	params.InitializationOptions = makeSettings(e.sandbox, config, nil)

	params.WorkspaceFolders = makeWorkspaceFolders(e.sandbox, config.WorkspaceFolders, config.NoDefaultWorkspaceFiles)
	params.RootURI = protocol.URIFromPath(config.RelRootPath)
	if !uriRE.MatchString(config.RelRootPath) { // relative file path
		params.RootURI = e.sandbox.Workdir.URI(config.RelRootPath)
	}

	capabilities, err := clientCapabilities(config)
	if err != nil {
		return fmt.Errorf("unmarshalling EditorConfig.CapabilitiesJSON: %v", err)
	}
	params.Capabilities = capabilities

	trace := protocol.TraceValue("messages")
	params.Trace = &trace
	// TODO: support workspace folders.
	if e.Server != nil {
		resp, err := e.Server.Initialize(ctx, params)
		if err != nil {
			return fmt.Errorf("initialize: %w", err)
		}
		semTokOpts, err := marshalUnmarshal[protocol.SemanticTokensOptions](resp.Capabilities.SemanticTokensProvider)
		if err != nil {
			return fmt.Errorf("unmarshalling semantic tokens options: %v", err)
		}
		e.serverCapabilities = resp.Capabilities
		e.semTokOpts = semTokOpts

		if err := e.Server.Initialized(ctx, &protocol.InitializedParams{}); err != nil {
			return fmt.Errorf("initialized: %w", err)
		}
	}
	// TODO: await initial configuration here, or expect gopls to manage that?
	return nil
}

func clientCapabilities(cfg EditorConfig) (protocol.ClientCapabilities, error) {
	var capabilities protocol.ClientCapabilities
	// Set various client capabilities that are sought by gopls.
	capabilities.Workspace.Configuration = true // support workspace/configuration
	capabilities.TextDocument.Completion.CompletionItem.TagSupport = &protocol.CompletionItemTagOptions{}
	capabilities.TextDocument.Completion.CompletionItem.TagSupport.ValueSet = []protocol.CompletionItemTag{protocol.ComplDeprecated}
	capabilities.TextDocument.Completion.CompletionItem.SnippetSupport = true
	capabilities.TextDocument.Completion.CompletionItem.InsertReplaceSupport = true
	capabilities.TextDocument.SemanticTokens.Requests.Full = &protocol.Or_ClientSemanticTokensRequestOptions_full{Value: true}
	capabilities.Window.WorkDoneProgress = true                                                // support window/workDoneProgress
	capabilities.Window.ShowDocument = &protocol.ShowDocumentClientCapabilities{Support: true} // support window/showDocument
	capabilities.TextDocument.SemanticTokens.TokenTypes = []string{
		"namespace", "type", "class", "enum", "interface",
		"struct", "typeParameter", "parameter", "variable", "property", "enumMember",
		"event", "function", "method", "macro", "keyword", "modifier", "comment",
		"string", "number", "regexp", "operator",
		// Additional types supported by this client:
		"label",
	}
	capabilities.TextDocument.SemanticTokens.TokenModifiers = []string{
		"declaration", "definition", "readonly", "static",
		"deprecated", "abstract", "async", "modification", "documentation", "defaultLibrary",
		// Additional modifiers supported by this client:
		"interface", "struct", "signature", "pointer", "array", "map", "slice", "chan", "string", "number", "bool", "invalid",
	}
	// Request that the server provide its complete list of code action kinds.
	capabilities.TextDocument.CodeAction = protocol.CodeActionClientCapabilities{
		DataSupport: true,
		ResolveSupport: &protocol.ClientCodeActionResolveOptions{
			Properties: []string{"edit"},
		},
		CodeActionLiteralSupport: protocol.ClientCodeActionLiteralOptions{
			CodeActionKind: protocol.ClientCodeActionKindOptions{
				ValueSet: []protocol.CodeActionKind{protocol.Empty}, // => all
			},
		},
	}
	// The LSP tests have historically enabled this flag,
	// but really we should test both ways for older editors.
	capabilities.TextDocument.DocumentSymbol.HierarchicalDocumentSymbolSupport = true
	// Glob pattern watching is enabled.
	capabilities.Workspace.DidChangeWatchedFiles.DynamicRegistration = true
	// "rename" operations are used for package renaming.
	//
	// TODO(rfindley): add support for other resource operations (create, delete, ...)
	capabilities.Workspace.WorkspaceEdit = &protocol.WorkspaceEditClientCapabilities{
		ResourceOperations: []protocol.ResourceOperationKind{
			"rename",
		},
	}

	// Apply capabilities overlay.
	if cfg.CapabilitiesJSON != nil {
		if err := json.Unmarshal(cfg.CapabilitiesJSON, &capabilities); err != nil {
			return protocol.ClientCapabilities{}, fmt.Errorf("unmarshalling EditorConfig.CapabilitiesJSON: %v", err)
		}
	}
	return capabilities, nil
}

// Returns the connected LSP server's capabilities.
// Only populated after a call to [Editor.Connect].
func (e *Editor) ServerCapabilities() protocol.ServerCapabilities {
	return e.serverCapabilities
}

// marshalUnmarshal is a helper to json Marshal and then Unmarshal as a
// different type. Used to work around cases where our protocol types are not
// specific.
func marshalUnmarshal[T any](v any) (T, error) {
	var t T
	data, err := json.Marshal(v)
	if err != nil {
		return t, err
	}
	err = json.Unmarshal(data, &t)
	return t, err
}

// HasCommand reports whether the connected server supports the command with the given ID.
func (e *Editor) HasCommand(cmd command.Command) bool {
	return slices.Contains(e.serverCapabilities.ExecuteCommandProvider.Commands, cmd.String())
}

// Examples: https://www.iana.org/assignments/uri-schemes/uri-schemes.xhtml
var uriRE = regexp.MustCompile(`^[a-z][a-z0-9+\-.]*://\S+`)

// makeWorkspaceFolders creates a slice of workspace folders to use for
// this editing session, based on the editor configuration.
func makeWorkspaceFolders(sandbox *Sandbox, paths []string, useEmpty bool) (folders []protocol.WorkspaceFolder) {
	if len(paths) == 0 {
		if useEmpty {
			return nil
		}
		paths = []string{string(sandbox.Workdir.RelativeTo)}
	}

	for _, path := range paths {
		uri := path
		if !uriRE.MatchString(path) { // relative file path
			uri = string(sandbox.Workdir.URI(path))
		}
		folders = append(folders, protocol.WorkspaceFolder{
			URI:  uri,
			Name: filepath.Base(uri),
		})
	}

	return folders
}

// onFileChanges is registered to be called by the Workdir on any writes that
// go through the Workdir API. It is called synchronously by the Workdir.
func (e *Editor) onFileChanges(ctx context.Context, evts []protocol.FileEvent) {
	if e.Server == nil {
		return
	}

	// e may be locked when onFileChanges is called, but it is important that we
	// synchronously increment this counter so that we can subsequently assert on
	// the number of expected DidChangeWatchedFiles calls.
	e.callsMu.Lock()
	e.calls.DidChangeWatchedFiles++
	e.callsMu.Unlock()

	// Since e may be locked, we must run this mutation asynchronously.
	go func() {
		e.mu.Lock()
		defer e.mu.Unlock()
		for _, evt := range evts {
			// Always send an on-disk change, even for events that seem useless
			// because they're shadowed by an open buffer.
			path := e.sandbox.Workdir.URIToPath(evt.URI)
			if buf, ok := e.buffers[path]; ok {
				// Following VS Code, don't honor deletions or changes to dirty buffers.
				if buf.dirty || evt.Type == protocol.Deleted {
					continue
				}

				content, err := e.sandbox.Workdir.ReadFile(path)
				if err != nil {
					continue // A race with some other operation.
				}
				// No need to update if the buffer content hasn't changed.
				if string(content) == buf.text() {
					continue
				}
				// During shutdown, this call will fail. Ignore the error.
				_ = e.setBufferContentLocked(ctx, path, false, content, nil)
			}
		}
		var matchedEvts []protocol.FileEvent
		for _, evt := range evts {
			filename := filepath.ToSlash(evt.URI.Path())
			for _, g := range e.watchPatterns {
				if g.Match(filename) {
					matchedEvts = append(matchedEvts, evt)
					break
				}
			}
		}

		// TODO(rfindley): don't send notifications while locked.
		e.Server.DidChangeWatchedFiles(ctx, &protocol.DidChangeWatchedFilesParams{
			Changes: matchedEvts,
		})
	}()
}

// OpenFile creates a buffer for the given workdir-relative file.
//
// If the file is already open, it is a no-op.
func (e *Editor) OpenFile(ctx context.Context, path string) error {
	if e.HasBuffer(path) {
		return nil
	}
	content, err := e.sandbox.Workdir.ReadFile(path)
	if err != nil {
		return err
	}
	if e.Config().WindowsLineEndings {
		content = toWindowsLineEndings(content)
	}
	return e.createBuffer(ctx, path, false, content)
}

// toWindowsLineEndings checks whether content has windows line endings.
//
// If so, it returns content unmodified. If not, it returns a new byte slice modified to use CRLF line endings.
func toWindowsLineEndings(content []byte) []byte {
	abnormal := false
	for i, b := range content {
		if b == '\n' && (i == 0 || content[i-1] != '\r') {
			abnormal = true
			break
		}
	}
	if !abnormal {
		return content
	}
	var buf bytes.Buffer
	for i, b := range content {
		if b == '\n' && (i == 0 || content[i-1] != '\r') {
			buf.WriteByte('\r')
		}
		buf.WriteByte(b)
	}
	return buf.Bytes()
}

// CreateBuffer creates a new unsaved buffer corresponding to the workdir path,
// containing the given textual content.
func (e *Editor) CreateBuffer(ctx context.Context, path, content string) error {
	return e.createBuffer(ctx, path, true, []byte(content))
}

func (e *Editor) createBuffer(ctx context.Context, path string, dirty bool, content []byte) error {
	e.mu.Lock()

	if _, ok := e.buffers[path]; ok {
		e.mu.Unlock()
		return fmt.Errorf("buffer %q already exists", path)
	}

	uri := e.sandbox.Workdir.URI(path)
	buf := buffer{
		version: 1,
		path:    path,
		mapper:  protocol.NewMapper(uri, content),
		dirty:   dirty,
	}
	e.buffers[path] = buf

	item := e.textDocumentItem(buf)
	e.mu.Unlock()

	return e.sendDidOpen(ctx, item)
}

// textDocumentItem builds a protocol.TextDocumentItem for the given buffer.
//
// Precondition: e.mu must be held.
func (e *Editor) textDocumentItem(buf buffer) protocol.TextDocumentItem {
	return protocol.TextDocumentItem{
		URI:        e.sandbox.Workdir.URI(buf.path),
		LanguageID: languageID(buf.path, e.config.FileAssociations),
		Version:    int32(buf.version),
		Text:       buf.text(),
	}
}

func (e *Editor) sendDidOpen(ctx context.Context, item protocol.TextDocumentItem) error {
	if e.Server != nil {
		if err := e.Server.DidOpen(ctx, &protocol.DidOpenTextDocumentParams{
			TextDocument: item,
		}); err != nil {
			return fmt.Errorf("DidOpen: %w", err)
		}
		e.callsMu.Lock()
		e.calls.DidOpen++
		e.callsMu.Unlock()
	}
	return nil
}

var defaultFileAssociations = map[protocol.LanguageKind]*regexp.Regexp{
	"go":      regexp.MustCompile(`^.*\.go$`), // '$' is important: don't match .gotmpl!
	"go.mod":  regexp.MustCompile(`^go\.mod$`),
	"go.sum":  regexp.MustCompile(`^go(\.work)?\.sum$`),
	"go.work": regexp.MustCompile(`^go\.work$`),
	"gotmpl":  regexp.MustCompile(`^.*tmpl$`),
	"go.s":    regexp.MustCompile(`\.s$`),
}

// languageID returns the language identifier for the path p given the user
// configured fileAssociations.
func languageID(p string, fileAssociations map[protocol.LanguageKind]string) protocol.LanguageKind {
	base := path.Base(p)
	for lang, re := range fileAssociations {
		re := regexp.MustCompile(re)
		if re.MatchString(base) {
			return lang
		}
	}
	for lang, re := range defaultFileAssociations {
		if re.MatchString(base) {
			return lang
		}
	}
	return ""
}

// CloseBuffer removes the current buffer (regardless of whether it is saved).
// CloseBuffer returns an error if the buffer is not open.
func (e *Editor) CloseBuffer(ctx context.Context, path string) error {
	e.mu.Lock()
	_, ok := e.buffers[path]
	if !ok {
		e.mu.Unlock()
		return ErrUnknownBuffer
	}
	delete(e.buffers, path)
	e.mu.Unlock()

	return e.sendDidClose(ctx, e.TextDocumentIdentifier(path))
}

func (e *Editor) sendDidClose(ctx context.Context, doc protocol.TextDocumentIdentifier) error {
	if e.Server != nil {
		if err := e.Server.DidClose(ctx, &protocol.DidCloseTextDocumentParams{
			TextDocument: doc,
		}); err != nil {
			return fmt.Errorf("DidClose: %w", err)
		}
		e.callsMu.Lock()
		e.calls.DidClose++
		e.callsMu.Unlock()
	}
	return nil
}

func (e *Editor) DocumentURI(path string) protocol.DocumentURI {
	return e.sandbox.Workdir.URI(path)
}

func (e *Editor) TextDocumentIdentifier(path string) protocol.TextDocumentIdentifier {
	return protocol.TextDocumentIdentifier{
		URI: e.DocumentURI(path),
	}
}

// SaveBuffer writes the content of the buffer specified by the given path to
// the filesystem.
func (e *Editor) SaveBuffer(ctx context.Context, path string) error {
	if err := e.OrganizeImports(ctx, path); err != nil {
		return fmt.Errorf("organizing imports before save: %w", err)
	}
	if err := e.FormatBuffer(ctx, path); err != nil {
		return fmt.Errorf("formatting before save: %w", err)
	}
	return e.SaveBufferWithoutActions(ctx, path)
}

func (e *Editor) SaveBufferWithoutActions(ctx context.Context, path string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	buf, ok := e.buffers[path]
	if !ok {
		return fmt.Errorf("unknown buffer: %q", path)
	}
	content := buf.text()
	includeText := false
	syncOptions, ok := e.serverCapabilities.TextDocumentSync.(protocol.TextDocumentSyncOptions)
	if ok {
		includeText = syncOptions.Save.IncludeText
	}

	docID := e.TextDocumentIdentifier(buf.path)
	if e.Server != nil {
		if err := e.Server.WillSave(ctx, &protocol.WillSaveTextDocumentParams{
			TextDocument: docID,
			Reason:       protocol.Manual,
		}); err != nil {
			return fmt.Errorf("WillSave: %w", err)
		}
	}
	if err := e.sandbox.Workdir.WriteFile(ctx, path, content); err != nil {
		return fmt.Errorf("writing %q: %w", path, err)
	}

	buf.dirty = false
	e.buffers[path] = buf

	if e.Server != nil {
		params := &protocol.DidSaveTextDocumentParams{
			TextDocument: docID,
		}
		if includeText {
			params.Text = &content
		}
		if err := e.Server.DidSave(ctx, params); err != nil {
			return fmt.Errorf("DidSave: %w", err)
		}
		e.callsMu.Lock()
		e.calls.DidSave++
		e.callsMu.Unlock()
	}
	return nil
}

// ErrNoMatch is returned if a regexp search fails.
var (
	ErrNoMatch       = errors.New("no match")
	ErrUnknownBuffer = errors.New("unknown buffer")
)

// regexpLocation returns the location of the first occurrence of either re
// or its singular subgroup. It returns ErrNoMatch if the regexp doesn't match.
func regexpLocation(mapper *protocol.Mapper, re string) (protocol.Location, error) {
	var start, end int
	rec, err := regexp.Compile(re)
	if err != nil {
		return protocol.Location{}, err
	}
	indexes := rec.FindSubmatchIndex(mapper.Content)
	if indexes == nil {
		return protocol.Location{}, ErrNoMatch
	}
	switch len(indexes) {
	case 2:
		// no subgroups: return the range of the regexp expression
		start, end = indexes[0], indexes[1]
	case 4:
		// one subgroup: return its range
		start, end = indexes[2], indexes[3]
	default:
		return protocol.Location{}, fmt.Errorf("invalid search regexp %q: expect either 0 or 1 subgroups, got %d", re, len(indexes)/2-1)
	}
	return mapper.OffsetLocation(start, end)
}

// RegexpSearch returns the Location of the first match for re in the buffer
// bufName. For convenience, RegexpSearch supports the following two modes:
//  1. If re has no subgroups, return the position of the match for re itself.
//  2. If re has one subgroup, return the position of the first subgroup.
//
// It returns an error re is invalid, has more than one subgroup, or doesn't
// match the buffer.
func (e *Editor) RegexpSearch(bufName, re string) (protocol.Location, error) {
	e.mu.Lock()
	buf, ok := e.buffers[bufName]
	e.mu.Unlock()
	if !ok {
		return protocol.Location{}, ErrUnknownBuffer
	}
	return regexpLocation(buf.mapper, re)
}

// RegexpReplace edits the buffer corresponding to path by replacing the first
// instance of re, or its first subgroup, with the replace text. See
// RegexpSearch for more explanation of these two modes.
// It returns an error if re is invalid, has more than one subgroup, or doesn't
// match the buffer.
func (e *Editor) RegexpReplace(ctx context.Context, path, re, replace string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	buf, ok := e.buffers[path]
	if !ok {
		return ErrUnknownBuffer
	}
	loc, err := regexpLocation(buf.mapper, re)
	if err != nil {
		return err
	}
	edits := []protocol.TextEdit{{
		Range:   loc.Range,
		NewText: replace,
	}}
	patched, err := applyEdits(buf.mapper, edits, e.config.WindowsLineEndings)
	if err != nil {
		return fmt.Errorf("editing %q: %v", path, err)
	}
	return e.setBufferContentLocked(ctx, path, true, patched, edits)
}

// EditBuffer applies the given test edits to the buffer identified by path.
func (e *Editor) EditBuffer(ctx context.Context, path string, edits []protocol.TextEdit) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	return e.editBufferLocked(ctx, path, edits)
}

func (e *Editor) SetBufferContent(ctx context.Context, path, content string) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	return e.setBufferContentLocked(ctx, path, true, []byte(content), nil)
}

// HasBuffer reports whether the file name is open in the editor.
func (e *Editor) HasBuffer(name string) bool {
	e.mu.Lock()
	defer e.mu.Unlock()
	_, ok := e.buffers[name]
	return ok
}

// BufferText returns the content of the buffer with the given name, or "" if
// the file at that path is not open. The second return value reports whether
// the file is open.
func (e *Editor) BufferText(name string) (string, bool) {
	e.mu.Lock()
	defer e.mu.Unlock()
	buf, ok := e.buffers[name]
	if !ok {
		return "", false
	}
	return buf.text(), true
}

// Mapper returns the protocol.Mapper for the given buffer name, if it is open.
func (e *Editor) Mapper(name string) (*protocol.Mapper, error) {
	e.mu.Lock()
	defer e.mu.Unlock()
	buf, ok := e.buffers[name]
	if !ok {
		return nil, fmt.Errorf("no mapper for %q", name)
	}
	return buf.mapper, nil
}

// BufferVersion returns the current version of the buffer corresponding to
// name (or 0 if it is not being edited).
func (e *Editor) BufferVersion(name string) int {
	e.mu.Lock()
	defer e.mu.Unlock()
	return e.buffers[name].version
}

func (e *Editor) editBufferLocked(ctx context.Context, path string, edits []protocol.TextEdit) error {
	buf, ok := e.buffers[path]
	if !ok {
		return fmt.Errorf("unknown buffer %q", path)
	}
	content, err := applyEdits(buf.mapper, edits, e.config.WindowsLineEndings)
	if err != nil {
		return fmt.Errorf("editing %q: %v; edits:\n%v", path, err, edits)
	}
	return e.setBufferContentLocked(ctx, path, true, content, edits)
}

func (e *Editor) setBufferContentLocked(ctx context.Context, path string, dirty bool, content []byte, fromEdits []protocol.TextEdit) error {
	buf, ok := e.buffers[path]
	if !ok {
		return fmt.Errorf("unknown buffer %q", path)
	}
	buf.mapper = protocol.NewMapper(buf.mapper.URI, content)
	buf.version++
	buf.dirty = dirty
	e.buffers[path] = buf

	// A simple heuristic: if there is only one edit, send it incrementally.
	// Otherwise, send the entire content.
	var evt protocol.TextDocumentContentChangeEvent
	if len(fromEdits) == 1 {
		evt.Range = &fromEdits[0].Range
		evt.Text = fromEdits[0].NewText
	} else {
		evt.Text = buf.text()
	}
	params := &protocol.DidChangeTextDocumentParams{
		TextDocument: protocol.VersionedTextDocumentIdentifier{
			Version:                int32(buf.version),
			TextDocumentIdentifier: e.TextDocumentIdentifier(buf.path),
		},
		ContentChanges: []protocol.TextDocumentContentChangeEvent{evt},
	}
	if e.Server != nil {
		if err := e.Server.DidChange(ctx, params); err != nil {
			return fmt.Errorf("DidChange: %w", err)
		}
		e.callsMu.Lock()
		e.calls.DidChange++
		e.callsMu.Unlock()
	}
	return nil
}

// Definitions returns the definitions of the symbol at the given
// location in an open buffer.
func (e *Editor) Definitions(ctx context.Context, loc protocol.Location) ([]protocol.Location, error) {
	if err := e.checkBufferLocation(loc); err != nil {
		return nil, err
	}
	params := &protocol.DefinitionParams{}
	params.TextDocument.URI = loc.URI
	params.Position = loc.Range.Start

	return e.Server.Definition(ctx, params)
}

// TypeDefinitions returns the type definitions of the symbol at the
// given location in an open buffer.
func (e *Editor) TypeDefinitions(ctx context.Context, loc protocol.Location) ([]protocol.Location, error) {
	if err := e.checkBufferLocation(loc); err != nil {
		return nil, err
	}
	params := &protocol.TypeDefinitionParams{}
	params.TextDocument.URI = loc.URI
	params.Position = loc.Range.Start
	params.Range = loc.Range

	return e.Server.TypeDefinition(ctx, params)
}

// Symbol performs a workspace symbol search using query
func (e *Editor) Symbol(ctx context.Context, query string) ([]protocol.SymbolInformation, error) {
	params := &protocol.WorkspaceSymbolParams{Query: query}
	return e.Server.Symbol(ctx, params)
}

// OrganizeImports requests and performs the source.organizeImports codeAction.
func (e *Editor) OrganizeImports(ctx context.Context, path string) error {
	loc := e.sandbox.Workdir.EntireFile(path)
	_, err := e.applyCodeActions(ctx, loc, nil, protocol.SourceOrganizeImports)
	return err
}

// RefactorRewrite requests and performs the source.refactorRewrite codeAction.
func (e *Editor) RefactorRewrite(ctx context.Context, loc protocol.Location) error {
	applied, err := e.applyCodeActions(ctx, loc, nil, protocol.RefactorRewrite)
	if err != nil {
		return err
	}
	if applied == 0 {
		return fmt.Errorf("no refactorings were applied")
	}
	return nil
}

// ApplyQuickFixes requests and performs the quickfix codeAction.
func (e *Editor) ApplyQuickFixes(ctx context.Context, loc protocol.Location, diagnostics []protocol.Diagnostic) error {
	applied, err := e.applyCodeActions(ctx, loc, diagnostics, protocol.SourceFixAll, protocol.QuickFix)
	if applied == 0 {
		return fmt.Errorf("no quick fixes were applied")
	}
	return err
}

// ApplyCodeAction applies the given code action.
func (e *Editor) ApplyCodeAction(ctx context.Context, action protocol.CodeAction) error {
	// Resolve the code actions if necessary and supported.
	if action.Edit == nil {
		editSupport, err := e.EditResolveSupport()
		if err != nil {
			return err
		}
		if editSupport {
			ca, err := e.Server.ResolveCodeAction(ctx, &action)
			if err != nil {
				return err
			}
			action = *ca
		}
	}

	if action.Edit != nil {
		for _, change := range action.Edit.DocumentChanges {
			if change.TextDocumentEdit != nil {
				path := e.sandbox.Workdir.URIToPath(change.TextDocumentEdit.TextDocument.URI)
				if int32(e.buffers[path].version) != change.TextDocumentEdit.TextDocument.Version {
					// Skip edits for old versions.
					continue
				}
				if err := e.EditBuffer(ctx, path, protocol.AsTextEdits(change.TextDocumentEdit.Edits)); err != nil {
					return fmt.Errorf("editing buffer %q: %w", path, err)
				}
			}
		}
	}
	// Execute any commands. The specification says that commands are
	// executed after edits are applied.
	if action.Command != nil {
		if err := e.ExecuteCommand(ctx, &protocol.ExecuteCommandParams{
			Command:   action.Command.Command,
			Arguments: action.Command.Arguments,
		}, nil); err != nil {
			return err
		}
	}
	// Some commands may edit files on disk.
	return e.sandbox.Workdir.CheckForFileChanges(ctx)
}

func (e *Editor) Diagnostics(ctx context.Context, path string) ([]protocol.Diagnostic, error) {
	if e.Server == nil {
		return nil, errors.New("not connected")
	}
	e.mu.Lock()
	capabilities := e.serverCapabilities.DiagnosticProvider
	e.mu.Unlock()

	if capabilities == nil {
		return nil, errors.New("server does not support pull diagnostics")
	}
	switch capabilities.Value.(type) {
	case nil:
		return nil, errors.New("server does not support pull diagnostics")
	case protocol.DiagnosticOptions:
	case protocol.DiagnosticRegistrationOptions:
		// We could optionally check TextDocumentRegistrationOptions here to
		// see if any filters apply to path.
	default:
		panic(fmt.Sprintf("unknown DiagnosticsProvider type %T", capabilities.Value))
	}

	params := &protocol.DocumentDiagnosticParams{
		TextDocument: e.TextDocumentIdentifier(path),
	}
	result, err := e.Server.Diagnostic(ctx, params)
	if err != nil {
		return nil, err
	}
	report, ok := result.Value.(protocol.RelatedFullDocumentDiagnosticReport)
	if !ok {
		return nil, fmt.Errorf("unexpected diagnostics report type %T", result)
	}
	return report.Items, nil
}

// GetQuickFixes returns the available quick fix code actions.
func (e *Editor) GetQuickFixes(ctx context.Context, loc protocol.Location, diagnostics []protocol.Diagnostic) ([]protocol.CodeAction, error) {
	return e.CodeActions(ctx, loc, diagnostics, protocol.QuickFix, protocol.SourceFixAll)
}

func (e *Editor) applyCodeActions(ctx context.Context, loc protocol.Location, diagnostics []protocol.Diagnostic, only ...protocol.CodeActionKind) (int, error) {
	actions, err := e.CodeActions(ctx, loc, diagnostics, only...)
	if err != nil {
		return 0, err
	}
	applied := 0
	for _, action := range actions {
		if action.Title == "" {
			return 0, fmt.Errorf("empty title for code action")
		}
		applied++
		if err := e.ApplyCodeAction(ctx, action); err != nil {
			return 0, err
		}
	}
	return applied, nil
}

// TODO(rfindley): add missing documentation to exported methods here.

func (e *Editor) CodeActions(ctx context.Context, loc protocol.Location, diagnostics []protocol.Diagnostic, only ...protocol.CodeActionKind) ([]protocol.CodeAction, error) {
	if e.Server == nil {
		return nil, nil
	}
	params := &protocol.CodeActionParams{}
	params.TextDocument.URI = loc.URI
	params.Context.Only = only
	params.Range = loc.Range // may be zero => whole file
	if diagnostics != nil {
		params.Context.Diagnostics = diagnostics
	}
	return e.Server.CodeAction(ctx, params)
}

func (e *Editor) ExecuteCodeLensCommand(ctx context.Context, path string, cmd command.Command, result any) error {
	lenses, err := e.CodeLens(ctx, path)
	if err != nil {
		return err
	}
	var lens protocol.CodeLens
	var found bool
	for _, l := range lenses {
		if l.Command.Command == cmd.String() {
			lens = l
			found = true
		}
	}
	if !found {
		return fmt.Errorf("found no command with the ID %s", cmd)
	}
	return e.ExecuteCommand(ctx, &protocol.ExecuteCommandParams{
		Command:   lens.Command.Command,
		Arguments: lens.Command.Arguments,
	}, result)
}

// ExecuteCommand makes a workspace/executeCommand request to the connected LSP
// server, if any.
//
// Result contains a pointer to a variable to be populated by json.Unmarshal.
func (e *Editor) ExecuteCommand(ctx context.Context, params *protocol.ExecuteCommandParams, result any) error {
	if e.Server == nil {
		return nil
	}
	var match bool
	if e.serverCapabilities.ExecuteCommandProvider != nil {
		// Ensure that this command was actually listed as a supported command.
		if slices.Contains(e.serverCapabilities.ExecuteCommandProvider.Commands, params.Command) {
			match = true
		}
	}
	if !match {
		return fmt.Errorf("unsupported command %q", params.Command)
	}
	response, err := e.Server.ExecuteCommand(ctx, params)
	if err != nil {
		return err
	}
	// Some commands use the go command, which writes directly to disk.
	// For convenience, check for those changes.
	if err := e.sandbox.Workdir.CheckForFileChanges(ctx); err != nil {
		return fmt.Errorf("checking for file changes: %v", err)
	}
	if result != nil {
		// ExecuteCommand already unmarshalled the response without knowing
		// its schema, using the generic map[string]any representation.
		// Encode and decode again, this time into a typed variable.
		//
		// This could be improved by generating a jsonrpc2 command client from the
		// command.Interface, but that should only be done if we're consolidating
		// this part of the tsprotocol generation.
		//
		// TODO(rfindley): we could also improve this by having ExecuteCommand return
		// a json.RawMessage, similar to what we do with arguments.
		data, err := json.Marshal(response)
		if err != nil {
			return bug.Errorf("marshalling response: %v", err)
		}
		if err := json.Unmarshal(data, result); err != nil {
			return fmt.Errorf("unmarshalling response: %v", err)
		}
	}
	return nil
}

// FormatBuffer gofmts a Go file.
func (e *Editor) FormatBuffer(ctx context.Context, path string) error {
	if e.Server == nil {
		return nil
	}
	e.mu.Lock()
	version := e.buffers[path].version
	e.mu.Unlock()
	params := &protocol.DocumentFormattingParams{}
	params.TextDocument.URI = e.sandbox.Workdir.URI(path)
	edits, err := e.Server.Formatting(ctx, params)
	if err != nil {
		return fmt.Errorf("textDocument/formatting: %w", err)
	}
	e.mu.Lock()
	defer e.mu.Unlock()
	if versionAfter := e.buffers[path].version; versionAfter != version {
		return fmt.Errorf("before receipt of formatting edits, buffer version changed from %d to %d", version, versionAfter)
	}
	if len(edits) == 0 {
		return nil
	}
	return e.editBufferLocked(ctx, path, edits)
}

func (e *Editor) checkBufferLocation(loc protocol.Location) error {
	e.mu.Lock()
	defer e.mu.Unlock()
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	buf, ok := e.buffers[path]
	if !ok {
		return fmt.Errorf("buffer %q is not open", path)
	}

	_, _, err := buf.mapper.RangeOffsets(loc.Range)
	return err
}

// RunGenerate runs `go generate` non-recursively in the workdir-relative dir
// path. It does not report any resulting file changes as a watched file
// change, so must be followed by a call to Workdir.CheckForFileChanges once
// the generate command has completed.
// TODO(rFindley): this shouldn't be necessary anymore. Delete it.
func (e *Editor) RunGenerate(ctx context.Context, dir string) error {
	if e.Server == nil {
		return nil
	}
	absDir := e.sandbox.Workdir.AbsPath(dir)
	cmd := command.NewGenerateCommand("", command.GenerateArgs{
		Dir:       protocol.URIFromPath(absDir),
		Recursive: false,
	})
	params := &protocol.ExecuteCommandParams{
		Command:   cmd.Command,
		Arguments: cmd.Arguments,
	}
	if err := e.ExecuteCommand(ctx, params, nil); err != nil {
		return fmt.Errorf("running generate: %v", err)
	}
	// Unfortunately we can't simply poll the workdir for file changes here,
	// because server-side command may not have completed. In integration tests, we can
	// Await this state change, but here we must delegate that responsibility to
	// the caller.
	return nil
}

// CodeLens executes a codelens request on the server.
func (e *Editor) CodeLens(ctx context.Context, path string) ([]protocol.CodeLens, error) {
	if e.Server == nil {
		return nil, nil
	}
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.CodeLensParams{
		TextDocument: e.TextDocumentIdentifier(path),
	}
	lens, err := e.Server.CodeLens(ctx, params)
	if err != nil {
		return nil, err
	}
	return lens, nil
}

// Completion executes a completion request on the server.
func (e *Editor) Completion(ctx context.Context, loc protocol.Location) (*protocol.CompletionList, error) {
	if e.Server == nil {
		return nil, nil
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.CompletionParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	completions, err := e.Server.Completion(ctx, params)
	if err != nil {
		return nil, err
	}
	return completions, nil
}

func (e *Editor) DidCreateFiles(ctx context.Context, files ...protocol.DocumentURI) error {
	if e.Server == nil {
		return nil
	}
	params := &protocol.CreateFilesParams{}
	for _, file := range files {
		params.Files = append(params.Files, protocol.FileCreate{
			URI: string(file),
		})
	}
	return e.Server.DidCreateFiles(ctx, params)
}

func (e *Editor) SetSuggestionInsertReplaceMode(_ context.Context, useReplaceMode bool) {
	e.mu.Lock()
	defer e.mu.Unlock()
	e.suggestionUseReplaceMode = useReplaceMode
}

// AcceptCompletion accepts a completion for the given item
// at the given position based on the editor's suggestion insert mode.
// The server provides separate insert/replace ranges only if the
// Editor declares `InsertReplaceSupport` capability during initialization.
// Otherwise, it returns a single range and the insert/replace mode is ignored.
func (e *Editor) AcceptCompletion(ctx context.Context, loc protocol.Location, item protocol.CompletionItem) error {
	if e.Server == nil {
		return nil
	}
	e.mu.Lock()
	defer e.mu.Unlock()
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	_, ok := e.buffers[path]
	if !ok {
		return fmt.Errorf("buffer %q is not open", path)
	}
	edit, err := protocol.SelectCompletionTextEdit(item, e.suggestionUseReplaceMode)
	if err != nil {
		return err
	}
	return e.editBufferLocked(ctx, path, append([]protocol.TextEdit{
		edit,
	}, item.AdditionalTextEdits...))
}

// Symbols executes a workspace/symbols request on the server.
func (e *Editor) Symbols(ctx context.Context, sym string) ([]protocol.SymbolInformation, error) {
	if e.Server == nil {
		return nil, nil
	}
	params := &protocol.WorkspaceSymbolParams{Query: sym}
	ans, err := e.Server.Symbol(ctx, params)
	return ans, err
}

// CodeLens executes a codelens request on the server.
func (e *Editor) InlayHint(ctx context.Context, path string) ([]protocol.InlayHint, error) {
	if e.Server == nil {
		return nil, nil
	}
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.InlayHintParams{
		TextDocument: e.TextDocumentIdentifier(path),
	}
	hints, err := e.Server.InlayHint(ctx, params)
	if err != nil {
		return nil, err
	}
	return hints, nil
}

// References returns references to the object at loc, as returned by
// the connected LSP server. If no server is connected, it returns (nil, nil).
func (e *Editor) References(ctx context.Context, loc protocol.Location) ([]protocol.Location, error) {
	if e.Server == nil {
		return nil, nil
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.ReferenceParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		Context: protocol.ReferenceContext{
			IncludeDeclaration: true,
		},
	}
	locations, err := e.Server.References(ctx, params)
	if err != nil {
		return nil, err
	}
	return locations, nil
}

// Rename performs a rename of the object at loc to newName, using the
// connected LSP server. If no server is connected, it returns nil.
func (e *Editor) Rename(ctx context.Context, loc protocol.Location, newName string) error {
	if e.Server == nil {
		return nil
	}

	// Verify that PrepareRename succeeds.
	prepareParams := &protocol.PrepareRenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	if _, err := e.Server.PrepareRename(ctx, prepareParams); err != nil {
		return fmt.Errorf("preparing rename: %v", err)
	}

	params := &protocol.RenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		NewName:                    newName,
	}
	wsedit, err := e.Server.Rename(ctx, params)
	if err != nil {
		return err
	}
	return e.applyWorkspaceEdit(ctx, wsedit)
}

// Implementations returns implementations for the object at loc, as
// returned by the connected LSP server. If no server is connected, it returns
// (nil, nil).
func (e *Editor) Implementations(ctx context.Context, loc protocol.Location) ([]protocol.Location, error) {
	if e.Server == nil {
		return nil, nil
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.ImplementationParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	return e.Server.Implementation(ctx, params)
}

func (e *Editor) SignatureHelp(ctx context.Context, loc protocol.Location) (*protocol.SignatureHelp, error) {
	if e.Server == nil {
		return nil, nil
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.SignatureHelpParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
	}
	return e.Server.SignatureHelp(ctx, params)
}

func (e *Editor) RenameFile(ctx context.Context, oldPath, newPath string) error {
	closed, opened, err := e.renameBuffers(oldPath, newPath)
	if err != nil {
		return err
	}

	for _, c := range closed {
		if err := e.sendDidClose(ctx, c); err != nil {
			return err
		}
	}
	for _, o := range opened {
		if err := e.sendDidOpen(ctx, o); err != nil {
			return err
		}
	}

	// Finally, perform the renaming on disk.
	if err := e.sandbox.Workdir.RenameFile(ctx, oldPath, newPath); err != nil {
		return fmt.Errorf("renaming sandbox file: %w", err)
	}
	return nil
}

// renameBuffers renames in-memory buffers affected by the renaming of
// oldPath->newPath, returning the resulting text documents that must be closed
// and opened over the LSP.
func (e *Editor) renameBuffers(oldPath, newPath string) (closed []protocol.TextDocumentIdentifier, opened []protocol.TextDocumentItem, _ error) {
	e.mu.Lock()
	defer e.mu.Unlock()

	// In case either oldPath or newPath is absolute, convert to absolute paths
	// before checking for containment.
	oldAbs := e.sandbox.Workdir.AbsPath(oldPath)
	newAbs := e.sandbox.Workdir.AbsPath(newPath)

	// Collect buffers that are affected by the given file or directory renaming.
	buffersToRename := make(map[string]string) // old path -> new path

	for path := range e.buffers {
		abs := e.sandbox.Workdir.AbsPath(path)
		if oldAbs == abs || pathutil.InDir(oldAbs, abs) {
			rel, err := filepath.Rel(oldAbs, abs)
			if err != nil {
				return nil, nil, fmt.Errorf("filepath.Rel(%q, %q): %v", oldAbs, abs, err)
			}
			nabs := filepath.Join(newAbs, rel)
			newPath := e.sandbox.Workdir.RelPath(nabs)
			buffersToRename[path] = newPath
		}
	}

	// Update buffers, and build protocol changes.
	for old, new := range buffersToRename {
		buf := e.buffers[old]
		delete(e.buffers, old)
		buf.version = 1
		buf.path = new
		e.buffers[new] = buf

		closed = append(closed, e.TextDocumentIdentifier(old))
		opened = append(opened, e.textDocumentItem(buf))
	}

	return closed, opened, nil
}

// applyWorkspaceEdit applies the sequence of document changes in
// wsedit to the Editor.
//
// See also:
//   - changedFiles in ../../marker/marker_test.go for the
//     handler used by the marker test to intercept edits.
//   - client.applyWorkspaceEdit in ../../../cmd/cmd.go for the
//     CLI variant.
func (e *Editor) applyWorkspaceEdit(ctx context.Context, wsedit *protocol.WorkspaceEdit) error {
	uriToPath := e.sandbox.Workdir.URIToPath

	for _, change := range wsedit.DocumentChanges {
		switch {
		case change.TextDocumentEdit != nil:
			if err := e.applyTextDocumentEdit(ctx, *change.TextDocumentEdit); err != nil {
				return err
			}

		case change.RenameFile != nil:
			old := uriToPath(change.RenameFile.OldURI)
			new := uriToPath(change.RenameFile.NewURI)
			if err := e.RenameFile(ctx, old, new); err != nil {
				return err
			}

		case change.CreateFile != nil:
			path := uriToPath(change.CreateFile.URI)
			if err := e.CreateBuffer(ctx, path, ""); err != nil {
				return err // e.g. already exists
			}

		case change.DeleteFile != nil:
			path := uriToPath(change.DeleteFile.URI)
			// The specified URI could be a file or a directory.
			files, err := e.sandbox.Workdir.ListFiles(path)
			if err != nil {
				return err
			}
			if len(files) > 0 {
				// Directory is not empty. If "Recursive" is true, we delete
				// every file in the folder. Otherwise, we continue without
				// deleting the directory.
				if change.DeleteFile.Options != nil && change.DeleteFile.Options.Recursive {
					for _, f := range files {
						_ = e.CloseBuffer(ctx, f) // returns error if not open
						if err := e.sandbox.Workdir.RemoveFile(ctx, f); err != nil {
							return err // e.g. doesn't exist
						}
					}
				}
				continue
			}
			_ = e.CloseBuffer(ctx, path) // returns error if not open
			if err := e.sandbox.Workdir.RemoveFile(ctx, path); err != nil {
				return err // e.g. doesn't exist
			}

		default:
			return bug.Errorf("invalid DocumentChange")
		}
	}
	return nil
}

func (e *Editor) applyTextDocumentEdit(ctx context.Context, change protocol.TextDocumentEdit) error {
	path := e.sandbox.Workdir.URIToPath(change.TextDocument.URI)
	if ver := int32(e.BufferVersion(path)); ver != change.TextDocument.Version {
		return fmt.Errorf("buffer versions for %q do not match: have %d, editing %d", path, ver, change.TextDocument.Version)
	}
	if !e.HasBuffer(path) {
		err := e.OpenFile(ctx, path)
		if os.IsNotExist(err) {
			// TODO: it's unclear if this is correct. Here we create the buffer (with
			// version 1), then apply edits. Perhaps we should apply the edits before
			// sending the didOpen notification.
			err = e.CreateBuffer(ctx, path, "")
		}
		if err != nil {
			return err
		}
	}
	return e.EditBuffer(ctx, path, protocol.AsTextEdits(change.Edits))
}

// Config returns the current editor configuration.
func (e *Editor) Config() EditorConfig {
	e.mu.Lock()
	defer e.mu.Unlock()
	return e.config
}

func (e *Editor) SetConfig(cfg EditorConfig) {
	e.mu.Lock()
	e.config = cfg
	e.mu.Unlock()
}

// ChangeConfiguration sets the new editor configuration, and if applicable
// sends a didChangeConfiguration notification.
//
// An error is returned if the change notification failed to send.
func (e *Editor) ChangeConfiguration(ctx context.Context, newConfig EditorConfig) error {
	e.SetConfig(newConfig)
	if e.Server != nil {
		var params protocol.DidChangeConfigurationParams // empty: gopls ignores the Settings field
		if err := e.Server.DidChangeConfiguration(ctx, &params); err != nil {
			return err
		}
		e.callsMu.Lock()
		e.calls.DidChangeConfiguration++
		e.callsMu.Unlock()
	}
	return nil
}

// ChangeWorkspaceFolders sets the new workspace folders, and sends a
// didChangeWorkspaceFolders notification to the server.
//
// The given folders must all be unique.
func (e *Editor) ChangeWorkspaceFolders(ctx context.Context, folders []string) error {
	config := e.Config()

	// capture existing folders so that we can compute the change.
	oldFolders := makeWorkspaceFolders(e.sandbox, config.WorkspaceFolders, config.NoDefaultWorkspaceFiles)
	newFolders := makeWorkspaceFolders(e.sandbox, folders, config.NoDefaultWorkspaceFiles)
	config.WorkspaceFolders = folders
	e.SetConfig(config)

	if e.Server == nil {
		return nil
	}

	var params protocol.DidChangeWorkspaceFoldersParams

	// Keep track of old workspace folders that must be removed.
	toRemove := make(map[protocol.URI]protocol.WorkspaceFolder)
	for _, folder := range oldFolders {
		toRemove[folder.URI] = folder
	}

	// Sanity check: if we see a folder twice the algorithm below doesn't work,
	// so track seen folders to ensure that we panic in that case.
	seen := make(map[protocol.URI]protocol.WorkspaceFolder)
	for _, folder := range newFolders {
		if _, ok := seen[folder.URI]; ok {
			panic(fmt.Sprintf("folder %s seen twice", folder.URI))
		}

		// If this folder already exists, we don't want to remove it.
		// Otherwise, we need to add it.
		if _, ok := toRemove[folder.URI]; ok {
			delete(toRemove, folder.URI)
		} else {
			params.Event.Added = append(params.Event.Added, folder)
		}
	}

	for _, v := range toRemove {
		params.Event.Removed = append(params.Event.Removed, v)
	}

	return e.Server.DidChangeWorkspaceFolders(ctx, &params)
}

// ResolveCodeAction executes a codeAction/resolve request on the server.
func (e *Editor) ResolveCodeAction(ctx context.Context, action *protocol.CodeAction) (*protocol.CodeAction, error) {
	if e.Server == nil {
		return nil, nil
	}
	return e.Server.ResolveCodeAction(ctx, action)
}

// CodeAction executes a codeAction request on the server.
// If loc.Range is zero, the whole file is implied.
// To reduce distraction, the trigger action (unknown, automatic, invoked)
// may affect what actions are offered.
func (e *Editor) CodeAction(ctx context.Context, loc protocol.Location, diagnostics []protocol.Diagnostic, trigger protocol.CodeActionTriggerKind) ([]protocol.CodeAction, error) {
	if e.Server == nil {
		return nil, nil
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	e.mu.Lock()
	_, ok := e.buffers[path]
	e.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("buffer %q is not open", path)
	}
	params := &protocol.CodeActionParams{
		TextDocument: e.TextDocumentIdentifier(path),
		Context: protocol.CodeActionContext{
			Diagnostics: diagnostics,
			TriggerKind: &trigger,
			Only:        []protocol.CodeActionKind{protocol.Empty}, // => all
		},
		Range: loc.Range, // may be zero
	}
	lens, err := e.Server.CodeAction(ctx, params)
	if err != nil {
		return nil, err
	}
	return lens, nil
}

func (e *Editor) EditResolveSupport() (bool, error) {
	capabilities, err := clientCapabilities(e.Config())
	if err != nil {
		return false, err
	}
	return capabilities.TextDocument.CodeAction.ResolveSupport != nil && slices.Contains(capabilities.TextDocument.CodeAction.ResolveSupport.Properties, "edit"), nil
}

// Hover triggers a hover at the given position in an open buffer.
// It may return (nil, zero) if no symbol was selected.
func (e *Editor) Hover(ctx context.Context, loc protocol.Location) (*protocol.MarkupContent, protocol.Location, error) {
	if err := e.checkBufferLocation(loc); err != nil {
		return nil, protocol.Location{}, err
	}
	params := &protocol.HoverParams{}
	params.TextDocument.URI = loc.URI
	params.Position = loc.Range.Start
	params.Range = loc.Range

	resp, err := e.Server.Hover(ctx, params)
	if err != nil {
		return nil, protocol.Location{}, fmt.Errorf("hover: %w", err)
	}
	if resp == nil {
		return nil, protocol.Location{}, nil // e.g. no selected symbol
	}
	return &resp.Contents, loc.URI.Location(resp.Range), nil
}

func (e *Editor) DocumentLink(ctx context.Context, path string) ([]protocol.DocumentLink, error) {
	if e.Server == nil {
		return nil, nil
	}
	params := &protocol.DocumentLinkParams{}
	params.TextDocument.URI = e.sandbox.Workdir.URI(path)
	return e.Server.DocumentLink(ctx, params)
}

func (e *Editor) DocumentHighlight(ctx context.Context, loc protocol.Location) ([]protocol.DocumentHighlight, error) {
	if e.Server == nil {
		return nil, nil
	}
	if err := e.checkBufferLocation(loc); err != nil {
		return nil, err
	}
	params := &protocol.DocumentHighlightParams{}
	params.TextDocument.URI = loc.URI
	params.Position = loc.Range.Start

	return e.Server.DocumentHighlight(ctx, params)
}

// SemanticTokensFull invokes textDocument/semanticTokens/full, and interprets
// its result.
func (e *Editor) SemanticTokensFull(ctx context.Context, path string) ([]SemanticToken, error) {
	p := &protocol.SemanticTokensParams{
		TextDocument: protocol.TextDocumentIdentifier{
			URI: e.sandbox.Workdir.URI(path),
		},
	}
	resp, err := e.Server.SemanticTokensFull(ctx, p)
	if err != nil {
		return nil, err
	}
	content, ok := e.BufferText(path)
	if !ok {
		return nil, fmt.Errorf("buffer %s is not open", path)
	}
	return e.interpretTokens(resp.Data, content), nil
}

// SemanticTokensRange invokes textDocument/semanticTokens/range, and
// interprets its result.
func (e *Editor) SemanticTokensRange(ctx context.Context, loc protocol.Location) ([]SemanticToken, error) {
	p := &protocol.SemanticTokensRangeParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
		Range:        loc.Range,
	}
	resp, err := e.Server.SemanticTokensRange(ctx, p)
	if err != nil {
		return nil, err
	}
	path := e.sandbox.Workdir.URIToPath(loc.URI)
	// As noted above: buffers should be keyed by protocol.DocumentURI.
	content, ok := e.BufferText(path)
	if !ok {
		return nil, fmt.Errorf("buffer %s is not open", path)
	}
	return e.interpretTokens(resp.Data, content), nil
}

// A SemanticToken is an interpreted semantic token value.
type SemanticToken struct {
	Token     string
	TokenType string
	Mod       string
}

// Note: previously this function elided comment, string, and number tokens.
// Instead, filtering of token types should be done by the caller.
func (e *Editor) interpretTokens(x []uint32, contents string) []SemanticToken {
	legend := e.semTokOpts.Legend
	lines := strings.Split(contents, "\n")
	ans := []SemanticToken{}
	line, col := 1, 1
	for i := 0; i < len(x); i += 5 {
		line += int(x[i])
		col += int(x[i+1])
		if x[i] != 0 { // new line
			col = int(x[i+1]) + 1 // 1-based column numbers
		}
		sz := x[i+2]
		t := legend.TokenTypes[x[i+3]]
		l := x[i+4]
		var mods []string
		for i, mod := range legend.TokenModifiers {
			if l&(1<<i) != 0 {
				mods = append(mods, mod)
			}
		}
		// Preexisting note: "col is a utf-8 offset"
		// TODO(rfindley): is that true? Or is it UTF-16, like other columns in the LSP?
		tok := lines[line-1][col-1 : col-1+int(sz)]
		ans = append(ans, SemanticToken{tok, t, strings.Join(mods, " ")})
	}
	return ans
}


================================================
FILE: gopls/internal/test/integration/fake/editor_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"context"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
)

const exampleProgram = `
-- go.mod --
go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}
`

func TestClientEditing(t *testing.T) {
	ws, err := NewSandbox(&SandboxConfig{Files: UnpackTxt(exampleProgram)})
	if err != nil {
		t.Fatal(err)
	}
	defer ws.Close()
	ctx := context.Background()
	editor := NewEditor(ws, EditorConfig{})
	if err := editor.OpenFile(ctx, "main.go"); err != nil {
		t.Fatal(err)
	}
	if err := editor.EditBuffer(ctx, "main.go", []protocol.TextEdit{
		{
			Range: protocol.Range{
				Start: protocol.Position{Line: 5, Character: 14},
				End:   protocol.Position{Line: 5, Character: 26},
			},
			NewText: "Hola, mundo.",
		},
	}); err != nil {
		t.Fatal(err)
	}
	got := editor.buffers["main.go"].text()
	want := `package main

import "fmt"

func main() {
	fmt.Println("Hola, mundo.")
}
`
	if got != want {
		t.Errorf("got text %q, want %q", got, want)
	}
}


================================================
FILE: gopls/internal/test/integration/fake/glob/glob.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package glob implements an LSP-compliant glob pattern matcher for testing.
package glob

import (
	"errors"
	"fmt"
	"strings"
	"unicode/utf8"
)

// A Glob is an LSP-compliant glob pattern, as defined by the spec:
// https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#documentFilter
//
// NOTE: this implementation is currently only intended for testing. In order
// to make it production ready, we'd need to:
//   - verify it against the VS Code implementation
//   - add more tests
//   - microbenchmark, likely avoiding the element interface
//   - resolve the question of what is meant by "character". If it's a UTF-16
//     code (as we suspect) it'll be a bit more work.
//
// Quoting from the spec:
// Glob patterns can have the following syntax:
//   - `*` to match one or more characters in a path segment
//   - `?` to match on one character in a path segment
//   - `**` to match any number of path segments, including none
//   - `{}` to group sub patterns into an OR expression. (e.g. `**/*.{ts,js}`
//     matches all TypeScript and JavaScript files)
//   - `[]` to declare a range of characters to match in a path segment
//     (e.g., `example.[0-9]` to match on `example.0`, `example.1`, …)
//   - `[!...]` to negate a range of characters to match in a path segment
//     (e.g., `example.[!0-9]` to match on `example.a`, `example.b`, but
//     not `example.0`)
//
// Expanding on this:
//   - '/' matches one or more literal slashes.
//   - any other character matches itself literally.
type Glob struct {
	elems []element // pattern elements
}

// Parse builds a Glob for the given pattern, returning an error if the pattern
// is invalid.
func Parse(pattern string) (*Glob, error) {
	g, _, err := parse(pattern, false)
	return g, err
}

func parse(pattern string, nested bool) (*Glob, string, error) {
	g := new(Glob)
	for len(pattern) > 0 {
		switch pattern[0] {
		case '/':
			pattern = pattern[1:]
			g.elems = append(g.elems, slash{})

		case '*':
			if len(pattern) > 1 && pattern[1] == '*' {
				if (len(g.elems) > 0 && g.elems[len(g.elems)-1] != slash{}) || (len(pattern) > 2 && pattern[2] != '/') {
					return nil, "", errors.New("** may only be adjacent to '/'")
				}
				pattern = pattern[2:]
				g.elems = append(g.elems, starStar{})
				break
			}
			pattern = pattern[1:]
			g.elems = append(g.elems, star{})

		case '?':
			pattern = pattern[1:]
			g.elems = append(g.elems, anyChar{})

		case '{':
			var gs group
			for pattern[0] != '}' {
				pattern = pattern[1:]
				g, pat, err := parse(pattern, true)
				if err != nil {
					return nil, "", err
				}
				if len(pat) == 0 {
					return nil, "", errors.New("unmatched '{'")
				}
				pattern = pat
				gs = append(gs, g)
			}
			pattern = pattern[1:]
			g.elems = append(g.elems, gs)

		case '}', ',':
			if nested {
				return g, pattern, nil
			}
			pattern = g.parseLiteral(pattern, false)

		case '[':
			pattern = pattern[1:]
			if len(pattern) == 0 {
				return nil, "", errBadRange
			}
			negate := false
			if pattern[0] == '!' {
				pattern = pattern[1:]
				negate = true
			}
			low, sz, err := readRangeRune(pattern)
			if err != nil {
				return nil, "", err
			}
			pattern = pattern[sz:]
			if len(pattern) == 0 || pattern[0] != '-' {
				return nil, "", errBadRange
			}
			pattern = pattern[1:]
			high, sz, err := readRangeRune(pattern)
			if err != nil {
				return nil, "", err
			}
			pattern = pattern[sz:]
			if len(pattern) == 0 || pattern[0] != ']' {
				return nil, "", errBadRange
			}
			pattern = pattern[1:]
			g.elems = append(g.elems, charRange{negate, low, high})

		default:
			pattern = g.parseLiteral(pattern, nested)
		}
	}
	return g, "", nil
}

// helper for decoding a rune in range elements, e.g. [a-z]
func readRangeRune(input string) (rune, int, error) {
	r, sz := utf8.DecodeRuneInString(input)
	var err error
	if r == utf8.RuneError {
		// See the documentation for DecodeRuneInString.
		switch sz {
		case 0:
			err = errBadRange
		case 1:
			err = errInvalidUTF8
		}
	}
	return r, sz, err
}

var (
	errBadRange    = errors.New("'[' patterns must be of the form [x-y]")
	errInvalidUTF8 = errors.New("invalid UTF-8 encoding")
)

func (g *Glob) parseLiteral(pattern string, nested bool) string {
	var specialChars string
	if nested {
		specialChars = "*?{[/},"
	} else {
		specialChars = "*?{[/"
	}
	end := strings.IndexAny(pattern, specialChars)
	if end == -1 {
		end = len(pattern)
	}
	g.elems = append(g.elems, literal(pattern[:end]))
	return pattern[end:]
}

func (g *Glob) String() string {
	var b strings.Builder
	for _, e := range g.elems {
		fmt.Fprint(&b, e)
	}
	return b.String()
}

// element holds a glob pattern element, as defined below.
type element fmt.Stringer

// element types.
type (
	slash     struct{} // One or more '/' separators
	literal   string   // string literal, not containing /, *, ?, {}, or []
	star      struct{} // *
	anyChar   struct{} // ?
	starStar  struct{} // **
	group     []*Glob  // {foo, bar, ...} grouping
	charRange struct { // [a-z] character range
		negate    bool
		low, high rune
	}
)

func (s slash) String() string    { return "/" }
func (l literal) String() string  { return string(l) }
func (s star) String() string     { return "*" }
func (a anyChar) String() string  { return "?" }
func (s starStar) String() string { return "**" }
func (g group) String() string {
	var parts []string
	for _, g := range g {
		parts = append(parts, g.String())
	}
	return "{" + strings.Join(parts, ",") + "}"
}
func (r charRange) String() string {
	return "[" + string(r.low) + "-" + string(r.high) + "]"
}

// Match reports whether the input string matches the glob pattern.
func (g *Glob) Match(input string) bool {
	return match(g.elems, input)
}

func match(elems []element, input string) (ok bool) {
	var elem any
	for len(elems) > 0 {
		elem, elems = elems[0], elems[1:]
		switch elem := elem.(type) {
		case slash:
			if len(input) == 0 || input[0] != '/' {
				return false
			}
			for input[0] == '/' {
				input = input[1:]
			}

		case starStar:
			// Special cases:
			//  - **/a matches "a"
			//  - **/ matches everything
			//
			// Note that if ** is followed by anything, it must be '/' (this is
			// enforced by Parse).
			if len(elems) > 0 {
				elems = elems[1:]
			}

			// A trailing ** matches anything.
			if len(elems) == 0 {
				return true
			}

			// Backtracking: advance pattern segments until the remaining pattern
			// elements match.
			for len(input) != 0 {
				if match(elems, input) {
					return true
				}
				_, input = split(input)
			}
			return false

		case literal:
			if !strings.HasPrefix(input, string(elem)) {
				return false
			}
			input = input[len(elem):]

		case star:
			var segInput string
			segInput, input = split(input)

			elemEnd := len(elems)
			for i, e := range elems {
				if e == (slash{}) {
					elemEnd = i
					break
				}
			}
			segElems := elems[:elemEnd]
			elems = elems[elemEnd:]

			// A trailing * matches the entire segment.
			if len(segElems) == 0 {
				break
			}

			// Backtracking: advance characters until remaining subpattern elements
			// match.
			matched := false
			for i := range segInput {
				if match(segElems, segInput[i:]) {
					matched = true
					break
				}
			}
			if !matched {
				return false
			}

		case anyChar:
			if len(input) == 0 || input[0] == '/' {
				return false
			}
			input = input[1:]

		case group:
			// Append remaining pattern elements to each group member looking for a
			// match.
			var branch []element
			for _, m := range elem {
				branch = branch[:0]
				branch = append(branch, m.elems...)
				branch = append(branch, elems...)
				if match(branch, input) {
					return true
				}
			}
			return false

		case charRange:
			if len(input) == 0 || input[0] == '/' {
				return false
			}
			c, sz := utf8.DecodeRuneInString(input)
			if c < elem.low || c > elem.high {
				return false
			}
			input = input[sz:]

		default:
			panic(fmt.Sprintf("segment type %T not implemented", elem))
		}
	}

	return len(input) == 0
}

// split returns the portion before and after the first slash
// (or sequence of consecutive slashes). If there is no slash
// it returns (input, nil).
func split(input string) (first, rest string) {
	i := strings.IndexByte(input, '/')
	if i < 0 {
		return input, ""
	}
	first = input[:i]
	for j := i; j < len(input); j++ {
		if input[j] != '/' {
			return first, input[j:]
		}
	}
	return first, ""
}


================================================
FILE: gopls/internal/test/integration/fake/glob/glob_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package glob_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/test/integration/fake/glob"
)

func TestParseErrors(t *testing.T) {
	tests := []string{
		"***",
		"ab{c",
		"[]",
		"[a-]",
		"ab{c{d}",
	}

	for _, test := range tests {
		_, err := glob.Parse(test)
		if err == nil {
			t.Errorf("Parse(%q) succeeded unexpectedly", test)
		}
	}
}

func TestMatch(t *testing.T) {
	tests := []struct {
		pattern, input string
		want           bool
	}{
		// Basic cases.
		{"", "", true},
		{"", "a", false},
		{"", "/", false},
		{"abc", "abc", true},

		// ** behavior
		{"**", "abc", true},
		{"**/abc", "abc", true},
		{"**", "abc/def", true},
		{"{a/**/c,a/**/d}", "a/b/c", true},
		{"{a/**/c,a/**/d}", "a/b/c/d", true},
		{"{a/**/c,a/**/e}", "a/b/c/d", false},
		{"{a/**/c,a/**/e,a/**/d}", "a/b/c/d", true},
		{"{/a/**/c,a/**/e,a/**/d}", "a/b/c/d", true},
		{"{/a/**/c,a/**/e,a/**/d}", "/a/b/c/d", false},
		{"{/a/**/c,a/**/e,a/**/d}", "/a/b/c", true},
		{"{/a/**/e,a/**/e,a/**/d}", "/a/b/c", false},

		// * and ? behavior
		{"/*", "/a", true},
		{"*", "foo", true},
		{"*o", "foo", true},
		{"*o", "foox", false},
		{"f*o", "foo", true},
		{"f*o", "fo", true},
		{"fo?", "foo", true},
		{"fo?", "fox", true},
		{"fo?", "fooo", false},
		{"fo?", "fo", false},
		{"?", "a", true},
		{"?", "ab", false},
		{"?", "", false},
		{"*?", "", false},
		{"?b", "ab", true},
		{"?c", "ab", false},

		// {} behavior
		{"ab{c,d}e", "abce", true},
		{"ab{c,d}e", "abde", true},
		{"ab{c,d}e", "abxe", false},
		{"ab{c,d}e", "abe", false},
		{"{a,b}c", "ac", true},
		{"{a,b}c", "bc", true},
		{"{a,b}c", "ab", false},
		{"a{b,c}", "ab", true},
		{"a{b,c}", "ac", true},
		{"a{b,c}", "bc", false},
		{"ab{c{1,2},d}e", "abc1e", true},
		{"ab{c{1,2},d}e", "abde", true},
		{"ab{c{1,2},d}e", "abc1f", false},
		{"ab{c{1,2},d}e", "abce", false},
		{"ab{c[}-~]}d", "abc}d", true},
		{"ab{c[}-~]}d", "abc~d", true},
		{"ab{c[}-~],y}d", "abcxd", false},
		{"ab{c[}-~],y}d", "abyd", true},
		{"ab{c[}-~],y}d", "abd", false},
		{"{a/b/c,d/e/f}", "a/b/c", true},
		{"/ab{/c,d}e", "/ab/ce", true},
		{"/ab{/c,d}e", "/ab/cf", false},

		// [-] behavior
		{"[a-c]", "a", true},
		{"[a-c]", "b", true},
		{"[a-c]", "c", true},
		{"[a-c]", "d", false},
		{"[a-c]", " ", false},

		// Realistic examples.
		{"**/*.{ts,js}", "path/to/foo.ts", true},
		{"**/*.{ts,js}", "path/to/foo.js", true},
		{"**/*.{ts,js}", "path/to/foo.go", false},
	}

	for _, test := range tests {
		g, err := glob.Parse(test.pattern)
		if err != nil {
			t.Fatalf("New(%q) failed unexpectedly: %v", test.pattern, err)
		}
		if got := g.Match(test.input); got != test.want {
			t.Errorf("New(%q).Match(%q) = %t, want %t", test.pattern, test.input, got, test.want)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/fake/proxy.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"fmt"
	"strings"

	"golang.org/x/tools/internal/proxydir"
)

// WriteProxy creates a new proxy file tree using the txtar-encoded content,
// and returns its URL.
func WriteProxy(tmpdir string, files map[string][]byte) (string, error) {
	type moduleVersion struct {
		modulePath, version string
	}
	// Transform into the format expected by the proxydir package.
	filesByModule := make(map[moduleVersion]map[string][]byte)
	for name, data := range files {
		modulePath, version, suffix := splitModuleVersionPath(name)
		mv := moduleVersion{modulePath, version}
		if _, ok := filesByModule[mv]; !ok {
			filesByModule[mv] = make(map[string][]byte)
		}
		filesByModule[mv][suffix] = data
	}
	for mv, files := range filesByModule {
		// Don't hoist this check out of the loop:
		// the problem is benign if filesByModule is empty.
		if strings.Contains(tmpdir, "#") {
			return "", fmt.Errorf("WriteProxy's tmpdir contains '#', which is unsuitable for GOPROXY. (If tmpdir was derived from testing.T.Name, use t.Run to ensure that each subtest has a unique name.)")
		}
		if err := proxydir.WriteModuleVersion(tmpdir, mv.modulePath, mv.version, files); err != nil {
			return "", fmt.Errorf("error writing %s@%s: %v", mv.modulePath, mv.version, err)
		}
	}
	return proxydir.ToURL(tmpdir), nil
}


================================================
FILE: gopls/internal/test/integration/fake/sandbox.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"context"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/robustio"
	"golang.org/x/tools/txtar"
)

// Sandbox holds a collection of temporary resources to use for working with Go
// code in tests.
type Sandbox struct {
	gopath          string
	rootdir         string
	goproxy         string
	Workdir         *Workdir
	goCommandRunner gocommand.Runner
}

// SandboxConfig controls the behavior of a test sandbox. The zero value
// defines a reasonable default.
type SandboxConfig struct {
	// RootDir sets the base directory to use when creating temporary
	// directories. If not specified, defaults to a new temporary directory.
	RootDir string
	// Files holds a txtar-encoded archive of files to populate the initial state
	// of the working directory.
	//
	// For convenience, the special substring "$SANDBOX_WORKDIR" is replaced with
	// the sandbox's resolved working directory before writing files.
	Files map[string][]byte
	// InGoPath specifies that the working directory should be within the
	// temporary GOPATH.
	InGoPath bool
	// Workdir configures the working directory of the Sandbox. It behaves as
	// follows:
	//  - if set to an absolute path, use that path as the working directory.
	//  - if set to a relative path, create and use that path relative to the
	//    sandbox.
	//  - if unset, default to a the 'work' subdirectory of the sandbox.
	//
	// This option is incompatible with InGoPath or Files.
	Workdir string
	// ProxyFiles holds a txtar-encoded archive of files to populate a file-based
	// Go proxy.
	ProxyFiles map[string][]byte
	// GOPROXY is the explicit GOPROXY value that should be used for the sandbox.
	//
	// This option is incompatible with ProxyFiles.
	GOPROXY string
}

// NewSandbox creates a collection of named temporary resources, with a
// working directory populated by the txtar-encoded content in srctxt, and a
// file-based module proxy populated with the txtar-encoded content in
// proxytxt.
//
// If rootDir is non-empty, it will be used as the root of temporary
// directories created for the sandbox. Otherwise, a new temporary directory
// will be used as root.
//
// TODO(rfindley): the sandbox abstraction doesn't seem to carry its weight.
// Sandboxes should be composed out of their building-blocks, rather than via a
// monolithic configuration.
func NewSandbox(config *SandboxConfig) (_ *Sandbox, err error) {
	if config == nil {
		config = new(SandboxConfig)
	}
	if err := validateConfig(*config); err != nil {
		return nil, fmt.Errorf("invalid SandboxConfig: %v", err)
	}

	sb := &Sandbox{}
	defer func() {
		// Clean up if we fail at any point in this constructor.
		if err != nil {
			sb.Close() // ignore error
		}
	}()

	rootDir := config.RootDir
	if rootDir == "" {
		rootDir, err = os.MkdirTemp(config.RootDir, "gopls-sandbox-")
		if err != nil {
			return nil, fmt.Errorf("creating temporary workdir: %v", err)
		}
	}
	sb.rootdir = rootDir
	sb.gopath = filepath.Join(sb.rootdir, "gopath")
	if err := os.Mkdir(sb.gopath, 0755); err != nil {
		return nil, err
	}
	if config.GOPROXY != "" {
		sb.goproxy = config.GOPROXY
	} else {
		proxydir := filepath.Join(sb.rootdir, "proxy")
		if err := os.Mkdir(proxydir, 0755); err != nil {
			return nil, err
		}
		sb.goproxy, err = WriteProxy(proxydir, config.ProxyFiles)
		if err != nil {
			return nil, err
		}
	}
	// Short-circuit writing the workdir if we're given an absolute path, since
	// this is used for running in an existing directory.
	// TODO(findleyr): refactor this to be less of a workaround.
	if filepath.IsAbs(config.Workdir) {
		sb.Workdir, err = NewWorkdir(config.Workdir, nil)
		if err != nil {
			return nil, err
		}
		return sb, nil
	}
	var workdir string
	if config.Workdir == "" {
		if config.InGoPath {
			// Set the working directory as $GOPATH/src.
			workdir = filepath.Join(sb.gopath, "src")
		} else if workdir == "" {
			workdir = filepath.Join(sb.rootdir, "work")
		}
	} else {
		// relative path
		workdir = filepath.Join(sb.rootdir, config.Workdir)
	}
	if err := os.MkdirAll(workdir, 0755); err != nil {
		return nil, err
	}
	sb.Workdir, err = NewWorkdir(workdir, config.Files)
	if err != nil {
		return nil, err
	}
	return sb, nil
}

func UnpackTxt(txt string) map[string][]byte {
	dataMap := make(map[string][]byte)
	archive := txtar.Parse([]byte(txt))
	for _, f := range archive.Files {
		if _, ok := dataMap[f.Name]; ok {
			panic(fmt.Sprintf("found file %q twice", f.Name))
		}
		dataMap[f.Name] = f.Data
	}
	return dataMap
}

func validateConfig(config SandboxConfig) error {
	if filepath.IsAbs(config.Workdir) && (len(config.Files) > 0 || config.InGoPath) {
		return errors.New("absolute Workdir cannot be set in conjunction with Files or InGoPath")
	}
	if config.Workdir != "" && config.InGoPath {
		return errors.New("Workdir cannot be set in conjunction with InGoPath")
	}
	if config.GOPROXY != "" && config.ProxyFiles != nil {
		return errors.New("GOPROXY cannot be set in conjunction with ProxyFiles")
	}
	return nil
}

// splitModuleVersionPath extracts module information from files stored in the
// directory structure modulePath@version/suffix.
// For example:
//
//	splitModuleVersionPath("mod.com@v1.2.3/package") = ("mod.com", "v1.2.3", "package")
func splitModuleVersionPath(path string) (modulePath, version, suffix string) {
	parts := strings.Split(path, "/")
	var modulePathParts []string
	for i, p := range parts {
		if strings.Contains(p, "@") {
			mv := strings.SplitN(p, "@", 2)
			modulePathParts = append(modulePathParts, mv[0])
			return strings.Join(modulePathParts, "/"), mv[1], strings.Join(parts[i+1:], "/")
		}
		modulePathParts = append(modulePathParts, p)
	}
	// Default behavior: this is just a module path.
	return path, "", ""
}

func (sb *Sandbox) RootDir() string {
	return sb.rootdir
}

// GOPATH returns the value of the Sandbox GOPATH.
func (sb *Sandbox) GOPATH() string {
	return sb.gopath
}

// GoEnv returns the default environment variables that can be used for
// invoking Go commands in the sandbox.
func (sb *Sandbox) GoEnv() map[string]string {
	return map[string]string{
		"GOPATH":           sb.GOPATH(),
		"GOPROXY":          sb.goproxy,
		"GO111MODULE":      "",
		"GOSUMDB":          "off",
		"GOPACKAGESDRIVER": "off",
		"GOTOOLCHAIN":      "local", // tests should not download toolchains
		// TODO(golang/go#74595): Why don't we respect GOMODCACHE in the
		// settings.env? See comment at env.CleanModCache.
		"GOMODCACHE": "",
	}
}

// goCommandInvocation returns a new gocommand.Invocation initialized with the
// sandbox environment variables and working directory.
func (sb *Sandbox) goCommandInvocation() gocommand.Invocation {
	var vars []string
	for k, v := range sb.GoEnv() {
		vars = append(vars, fmt.Sprintf("%s=%s", k, v))
	}
	inv := gocommand.Invocation{
		Env: vars,
	}
	// sb.Workdir may be nil if we exited the constructor with errors (we call
	// Close to clean up any partial state from the constructor, which calls
	// RunGoCommand).
	if sb.Workdir != nil {
		inv.WorkingDir = string(sb.Workdir.RelativeTo)
	}
	return inv
}

// RunGoCommand executes a go command in the sandbox and returns its standard
// output. If checkForFileChanges is true, the sandbox scans the working
// directory and emits file change events for any file changes it finds.
func (sb *Sandbox) RunGoCommand(ctx context.Context, dir, verb string, args, env []string, checkForFileChanges bool) ([]byte, error) {
	inv := sb.goCommandInvocation()
	inv.Verb = verb
	inv.Args = args
	inv.Env = append(inv.Env, env...)
	if dir != "" {
		inv.WorkingDir = sb.Workdir.AbsPath(dir)
	}
	stdout, stderr, _, err := sb.goCommandRunner.RunRaw(ctx, inv)
	if err != nil {
		return nil, fmt.Errorf("go command failed (stdout: %s) (stderr: %s): %v", stdout.String(), stderr.String(), err)
	}
	// Since running a go command may result in changes to workspace files,
	// check if we need to send any "watched" file events.
	//
	// TODO(rFindley): this side-effect can impact the usability of the sandbox
	//                 for benchmarks. Consider refactoring.
	if sb.Workdir != nil && checkForFileChanges {
		if err := sb.Workdir.CheckForFileChanges(ctx); err != nil {
			return nil, fmt.Errorf("checking for file changes: %w", err)
		}
	}
	return stdout.Bytes(), nil
}

// GoVersion checks the version of the go command.
// It returns the X in Go 1.X.
func (sb *Sandbox) GoVersion(ctx context.Context) (int, error) {
	inv := sb.goCommandInvocation()
	return gocommand.GoVersion(ctx, inv, &sb.goCommandRunner)
}

// Close removes all state associated with the sandbox.
func (sb *Sandbox) Close() error {
	var goCleanErr error
	// Careful: sb may not be fully initialized.
	if sb.gopath != "" && sb.Workdir != nil {
		// Important: run this command in RootDir so that it doesn't interact with
		// any toolchain downloads that may occur
		_, goCleanErr = sb.RunGoCommand(context.Background(), sb.RootDir(), "clean", []string{"-modcache"}, nil, false)
	}
	err := robustio.RemoveAll(sb.rootdir)
	if err != nil || goCleanErr != nil {
		return fmt.Errorf("error(s) cleaning sandbox: cleaning modcache: %v; removing files: %v", goCleanErr, err)
	}
	return nil
}


================================================
FILE: gopls/internal/test/integration/fake/workdir.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"bytes"
	"context"
	"crypto/sha256"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"runtime"
	"slices"
	"sort"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/robustio"
)

// RelativeTo is a helper for operations relative to a given directory.
type RelativeTo string

// AbsPath returns an absolute filesystem path for the workdir-relative path.
func (r RelativeTo) AbsPath(path string) string {
	fp := filepath.FromSlash(path)
	if filepath.IsAbs(fp) {
		return fp
	}
	return filepath.Join(string(r), filepath.FromSlash(path))
}

// RelPath returns a '/'-encoded path relative to the working directory (or an
// absolute path if the file is outside of workdir)
func (r RelativeTo) RelPath(fp string) string {
	root := string(r)
	if rel, err := filepath.Rel(root, fp); err == nil && !strings.HasPrefix(rel, "..") {
		return filepath.ToSlash(rel)
	}
	return filepath.ToSlash(fp)
}

// writeFileData writes content to the relative path, replacing the special
// token $SANDBOX_WORKDIR with the relative root given by rel. It does not
// trigger any file events.
func writeFileData(path string, content []byte, rel RelativeTo) error {
	content = bytes.ReplaceAll(content, []byte("$SANDBOX_WORKDIR"), []byte(rel))
	fp := rel.AbsPath(path)
	if err := os.MkdirAll(filepath.Dir(fp), 0755); err != nil {
		return fmt.Errorf("creating nested directory: %w", err)
	}
	backoff := 1 * time.Millisecond
	for {
		err := os.WriteFile(fp, content, 0644)
		if err != nil {
			// This lock file violation is not handled by the robustio package, as it
			// indicates a real race condition that could be avoided.
			if isWindowsErrLockViolation(err) {
				time.Sleep(backoff)
				backoff *= 2
				continue
			}
			return fmt.Errorf("writing %q: %w", path, err)
		}
		return nil
	}
}

// isWindowsErrLockViolation reports whether err is ERROR_LOCK_VIOLATION
// on Windows.
var isWindowsErrLockViolation = func(error) bool { return false }

// Workdir is a temporary working directory for tests. It exposes file
// operations in terms of relative paths, and fakes file watching by triggering
// events on file operations.
type Workdir struct {
	RelativeTo

	watcherMu sync.Mutex
	watchers  []func(context.Context, []protocol.FileEvent)

	fileMu sync.Mutex
	// File identities we know about, for the purpose of detecting changes.
	//
	// Since files is only used for detecting _changes_, we are tolerant of
	// fileIDs that may have hash and mtime coming from different states of the
	// file: if either are out of sync, then the next poll should detect a
	// discrepancy. It is OK if we detect too many changes, but not OK if we miss
	// changes.
	//
	// For that matter, this mechanism for detecting changes can still be flaky
	// on platforms where mtime is very coarse (such as older versions of WSL).
	// It would be much better to use a proper fs event library, but we can't
	// currently import those into x/tools.
	//
	// TODO(golang/go#52284): replace this polling mechanism with a
	// cross-platform library for filesystem notifications.
	files map[string]fileID
}

// NewWorkdir writes the txtar-encoded file data in txt to dir, and returns a
// Workdir for operating on these files using relative paths.
func NewWorkdir(dir string, files map[string][]byte) (*Workdir, error) {
	w := &Workdir{RelativeTo: RelativeTo(dir)}
	for name, data := range files {
		if err := writeFileData(name, data, w.RelativeTo); err != nil {
			return nil, fmt.Errorf("writing to workdir: %w", err)
		}
	}
	_, err := w.pollFiles() // poll files to populate the files map.
	return w, err
}

// fileID identifies a file version on disk.
type fileID struct {
	mtime time.Time
	hash  string // empty if mtime is old enough to be reliable; otherwise a file digest
}

func hashFile(data []byte) string {
	return fmt.Sprintf("%x", sha256.Sum256(data))
}

// RootURI returns the root URI for this working directory of this scratch
// environment.
func (w *Workdir) RootURI() protocol.DocumentURI {
	return protocol.URIFromPath(string(w.RelativeTo))
}

// AddWatcher registers the given func to be called on any file change.
func (w *Workdir) AddWatcher(watcher func(context.Context, []protocol.FileEvent)) {
	w.watcherMu.Lock()
	w.watchers = append(w.watchers, watcher)
	w.watcherMu.Unlock()
}

// URI returns the URI to a the workdir-relative path.
func (w *Workdir) URI(path string) protocol.DocumentURI {
	return protocol.URIFromPath(w.AbsPath(path))
}

// URIToPath converts a uri to a workdir-relative path (or an absolute path,
// if the uri is outside of the workdir).
func (w *Workdir) URIToPath(uri protocol.DocumentURI) string {
	return w.RelPath(uri.Path())
}

// EntireFile returns the entire extent of the file named by the workdir-relative path.
func (w *Workdir) EntireFile(path string) protocol.Location {
	return protocol.Location{URI: w.URI(path)}
}

// ReadFile reads a text file specified by a workdir-relative path.
func (w *Workdir) ReadFile(path string) ([]byte, error) {
	backoff := 1 * time.Millisecond
	for {
		b, err := os.ReadFile(w.AbsPath(path))
		if err != nil {
			if runtime.GOOS == "plan9" && strings.HasSuffix(err.Error(), " exclusive use file already open") {
				// Plan 9 enforces exclusive access to locked files.
				// Give the owner time to unlock it and retry.
				time.Sleep(backoff)
				backoff *= 2
				continue
			}
			return nil, err
		}
		return b, nil
	}
}

// RegexpSearch searches the file corresponding to path for the first position
// matching re.
func (w *Workdir) RegexpSearch(path string, re string) (protocol.Location, error) {
	content, err := w.ReadFile(path)
	if err != nil {
		return protocol.Location{}, err
	}
	mapper := protocol.NewMapper(w.URI(path), content)
	return regexpLocation(mapper, re)
}

// RemoveFile removes a workdir-relative file path and notifies watchers of the
// change.
func (w *Workdir) RemoveFile(ctx context.Context, path string) error {
	fp := w.AbsPath(path)
	if err := robustio.RemoveAll(fp); err != nil {
		return fmt.Errorf("removing %q: %w", path, err)
	}

	return w.CheckForFileChanges(ctx)
}

// WriteFiles writes the text file content to workdir-relative paths and
// notifies watchers of the changes.
func (w *Workdir) WriteFiles(ctx context.Context, files map[string]string) error {
	for path, content := range files {
		fp := w.AbsPath(path)
		_, err := os.Stat(fp)
		if err != nil && !os.IsNotExist(err) {
			return fmt.Errorf("checking if %q exists: %w", path, err)
		}
		if err := writeFileData(path, []byte(content), w.RelativeTo); err != nil {
			return err
		}
	}
	return w.CheckForFileChanges(ctx)
}

// WriteFile writes text file content to a workdir-relative path and notifies
// watchers of the change.
func (w *Workdir) WriteFile(ctx context.Context, path, content string) error {
	return w.WriteFiles(ctx, map[string]string{path: content})
}

// RenameFile performs an on disk-renaming of the workdir-relative oldPath to
// workdir-relative newPath, and notifies watchers of the changes.
//
// oldPath must either be a regular file or in the same directory as newPath.
func (w *Workdir) RenameFile(ctx context.Context, oldPath, newPath string) error {
	oldAbs := w.AbsPath(oldPath)
	newAbs := w.AbsPath(newPath)

	// For os.Rename, “OS-specific restrictions may apply when oldpath and newpath
	// are in different directories.” If that applies here, we may fall back to
	// ReadFile, WriteFile, and RemoveFile to perform the rename non-atomically.
	//
	// However, the fallback path only works for regular files: renaming a
	// directory would be much more complex and isn't needed for our tests.
	fallbackOk := false
	if filepath.Dir(oldAbs) != filepath.Dir(newAbs) {
		fi, err := os.Stat(oldAbs)
		if err == nil && !fi.Mode().IsRegular() {
			return &os.PathError{
				Op:   "RenameFile",
				Path: oldPath,
				Err:  fmt.Errorf("%w: file is not regular and not in the same directory as %s", os.ErrInvalid, newPath),
			}
		}
		fallbackOk = true
	}

	var renameErr error
	const debugFallback = false
	if fallbackOk && debugFallback {
		renameErr = fmt.Errorf("%w: debugging fallback path", os.ErrInvalid)
	} else {
		renameErr = robustio.Rename(oldAbs, newAbs)
	}
	if renameErr != nil {
		if !fallbackOk {
			return renameErr // The OS-specific Rename restrictions do not apply.
		}

		content, err := w.ReadFile(oldPath)
		if err != nil {
			// If we can't even read the file, the error from Rename may be accurate.
			return renameErr
		}
		fi, err := os.Stat(newAbs)
		if err == nil {
			if fi.IsDir() {
				// “If newpath already exists and is not a directory, Rename replaces it.”
				// But if it is a directory, maybe not?
				return renameErr
			}
			// On most platforms, Rename replaces the named file with a new file,
			// rather than overwriting the existing file it in place. Mimic that
			// behavior here.
			if err := robustio.RemoveAll(newAbs); err != nil {
				// Maybe we don't have permission to replace newPath?
				return renameErr
			}
		} else if !os.IsNotExist(err) {
			// If the destination path already exists or there is some problem with it,
			// the error from Rename may be accurate.
			return renameErr
		}
		if writeErr := writeFileData(newPath, content, w.RelativeTo); writeErr != nil {
			// At this point we have tried to actually write the file.
			// If it still doesn't exist, assume that the error from Rename was accurate:
			// for example, maybe we don't have permission to create the new path.
			// Otherwise, return the error from the write, which may indicate some
			// other problem (such as a full disk).
			if _, statErr := os.Stat(newAbs); !os.IsNotExist(statErr) {
				return writeErr
			}
			return renameErr
		}
		if err := robustio.RemoveAll(oldAbs); err != nil {
			// If we failed to remove the old file, that may explain the Rename error too.
			// Make a best effort to back out the write to the new path.
			robustio.RemoveAll(newAbs) // ignore error
			return renameErr
		}
	}

	return w.CheckForFileChanges(ctx)
}

// ListFiles returns a new sorted list of the relative paths of files in dir,
// recursively.
func (w *Workdir) ListFiles(dir string) ([]string, error) {
	absDir := w.AbsPath(dir)
	var paths []string
	if err := filepath.Walk(absDir, func(fp string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.Mode()&(fs.ModeDir|fs.ModeSymlink) == 0 {
			paths = append(paths, w.RelPath(fp))
		}
		return nil
	}); err != nil {
		return nil, err
	}
	sort.Strings(paths)
	return paths, nil
}

// CheckForFileChanges walks the working directory and checks for any files
// that have changed since the last poll.
func (w *Workdir) CheckForFileChanges(ctx context.Context) error {
	evts, err := w.pollFiles()
	if err != nil {
		return err
	}
	if len(evts) == 0 {
		return nil
	}
	w.watcherMu.Lock()
	watchers := slices.Clone(w.watchers)
	w.watcherMu.Unlock()
	for _, w := range watchers {
		w(ctx, evts)
	}
	return nil
}

// pollFiles updates w.files and calculates FileEvents corresponding to file
// state changes since the last poll. It does not call sendEvents.
func (w *Workdir) pollFiles() ([]protocol.FileEvent, error) {
	w.fileMu.Lock()
	defer w.fileMu.Unlock()

	newFiles := make(map[string]fileID)
	var evts []protocol.FileEvent
	if err := filepath.Walk(string(w.RelativeTo), func(fp string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		// Skip directories and symbolic links (which may be links to directories).
		//
		// The latter matters for repos like Kubernetes, which use symlinks.
		if info.Mode()&(fs.ModeDir|fs.ModeSymlink) != 0 {
			return nil
		}

		// Opt: avoid reading the file if mtime is sufficiently old to be reliable.
		//
		// If mtime is recent, it may not sufficiently identify the file contents:
		// a subsequent write could result in the same mtime. For these cases, we
		// must read the file contents.
		id := fileID{mtime: info.ModTime()}
		if time.Since(info.ModTime()) < 2*time.Second {
			data, err := os.ReadFile(fp)
			if err != nil {
				return err
			}
			id.hash = hashFile(data)
		}
		path := w.RelPath(fp)
		newFiles[path] = id

		if w.files != nil {
			oldID, ok := w.files[path]
			delete(w.files, path)
			switch {
			case !ok:
				evts = append(evts, protocol.FileEvent{
					URI:  w.URI(path),
					Type: protocol.Created,
				})
			case oldID != id:
				changed := true

				// Check whether oldID and id do not match because oldID was polled at
				// a recent enough to time such as to require hashing.
				//
				// In this case, read the content to check whether the file actually
				// changed.
				if oldID.mtime.Equal(id.mtime) && oldID.hash != "" && id.hash == "" {
					data, err := os.ReadFile(fp)
					if err != nil {
						return err
					}
					if hashFile(data) == oldID.hash {
						changed = false
					}
				}
				if changed {
					evts = append(evts, protocol.FileEvent{
						URI:  w.URI(path),
						Type: protocol.Changed,
					})
				}
			}
		}

		return nil
	}); err != nil {
		return nil, err
	}

	// Any remaining files must have been deleted.
	for path := range w.files {
		evts = append(evts, protocol.FileEvent{
			URI:  w.URI(path),
			Type: protocol.Deleted,
		})
	}
	w.files = newFiles
	return evts, nil
}


================================================
FILE: gopls/internal/test/integration/fake/workdir_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"context"
	"os"
	"sync"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
)

const sharedData = `
-- go.mod --
go 1.12
-- nested/README.md --
Hello World!
`

// newWorkdir sets up a temporary Workdir with the given txtar-encoded content.
// It also configures an eventBuffer to receive file event notifications. These
// notifications are sent synchronously for each operation, such that once a
// workdir file operation has returned the caller can expect that any relevant
// file notifications are present in the buffer.
//
// It is the caller's responsibility to call the returned cleanup function.
func newWorkdir(t *testing.T, txt string) (*Workdir, *eventBuffer, func()) {
	t.Helper()

	tmpdir, err := os.MkdirTemp("", "goplstest-workdir-")
	if err != nil {
		t.Fatal(err)
	}
	wd, err := NewWorkdir(tmpdir, UnpackTxt(txt))
	if err != nil {
		t.Fatal(err)
	}
	cleanup := func() {
		if err := os.RemoveAll(tmpdir); err != nil {
			t.Error(err)
		}
	}

	buf := new(eventBuffer)
	wd.AddWatcher(buf.onEvents)
	return wd, buf, cleanup
}

// eventBuffer collects events from a file watcher.
type eventBuffer struct {
	mu     sync.Mutex
	events []protocol.FileEvent
}

// onEvents collects adds events to the buffer; to be used with Workdir.AddWatcher.
func (c *eventBuffer) onEvents(_ context.Context, events []protocol.FileEvent) {
	c.mu.Lock()
	defer c.mu.Unlock()

	c.events = append(c.events, events...)
}

// take empties the buffer, returning its previous contents.
func (c *eventBuffer) take() []protocol.FileEvent {
	c.mu.Lock()
	defer c.mu.Unlock()

	evts := c.events
	c.events = nil
	return evts
}

func TestWorkdir_ReadFile(t *testing.T) {
	wd, _, cleanup := newWorkdir(t, sharedData)
	defer cleanup()

	got, err := wd.ReadFile("nested/README.md")
	if err != nil {
		t.Fatal(err)
	}
	want := "Hello World!\n"
	if got := string(got); got != want {
		t.Errorf("reading workdir file, got %q, want %q", got, want)
	}
}

func TestWorkdir_WriteFile(t *testing.T) {
	wd, events, cleanup := newWorkdir(t, sharedData)
	defer cleanup()
	ctx := context.Background()

	tests := []struct {
		path     string
		wantType protocol.FileChangeType
	}{
		{"data.txt", protocol.Created},
		{"nested/README.md", protocol.Changed},
	}

	for _, test := range tests {
		if err := wd.WriteFile(ctx, test.path, "42"); err != nil {
			t.Fatal(err)
		}
		es := events.take()
		if got := len(es); got != 1 {
			t.Fatalf("len(events) = %d, want 1", got)
		}
		path := wd.URIToPath(es[0].URI)
		if path != test.path {
			t.Errorf("event path = %q, want %q", path, test.path)
		}
		if es[0].Type != test.wantType {
			t.Errorf("event type = %v, want %v", es[0].Type, test.wantType)
		}
		got, err := wd.ReadFile(test.path)
		if err != nil {
			t.Fatal(err)
		}
		want := "42"
		if got := string(got); got != want {
			t.Errorf("ws.ReadFile(%q) = %q, want %q", test.path, got, want)
		}
	}
}

// Test for file notifications following file operations.
func TestWorkdir_FileWatching(t *testing.T) {
	wd, events, cleanup := newWorkdir(t, "")
	defer cleanup()
	ctx := context.Background()

	must := func(err error) {
		if err != nil {
			t.Fatal(err)
		}
	}

	type changeMap map[string]protocol.FileChangeType
	checkEvent := func(wantChanges changeMap) {
		gotChanges := make(changeMap)
		for _, e := range events.take() {
			gotChanges[wd.URIToPath(e.URI)] = e.Type
		}
		if diff := cmp.Diff(wantChanges, gotChanges); diff != "" {
			t.Errorf("mismatching file events (-want +got):\n%s", diff)
		}
	}

	must(wd.WriteFile(ctx, "foo.go", "package foo"))
	checkEvent(changeMap{"foo.go": protocol.Created})

	must(wd.RenameFile(ctx, "foo.go", "bar.go"))
	checkEvent(changeMap{"foo.go": protocol.Deleted, "bar.go": protocol.Created})

	must(wd.RemoveFile(ctx, "bar.go"))
	checkEvent(changeMap{"bar.go": protocol.Deleted})
}

func TestWorkdir_CheckForFileChanges(t *testing.T) {
	t.Skip("broken on darwin-amd64-10_12")
	wd, events, cleanup := newWorkdir(t, sharedData)
	defer cleanup()
	ctx := context.Background()

	checkChange := func(wantPath string, wantType protocol.FileChangeType) {
		if err := wd.CheckForFileChanges(ctx); err != nil {
			t.Fatal(err)
		}
		ev := events.take()
		if len(ev) == 0 {
			t.Fatal("no file events received")
		}
		gotEvt := ev[0]
		gotPath := wd.URIToPath(gotEvt.URI)
		// Only check relative path and Type
		if gotPath != wantPath || gotEvt.Type != wantType {
			t.Errorf("file events: got %v, want {Path: %s, Type: %v}", gotEvt, wantPath, wantType)
		}
	}
	// Sleep some positive amount of time to ensure a distinct mtime.
	if err := writeFileData("go.mod", []byte("module foo.test\n"), wd.RelativeTo); err != nil {
		t.Fatal(err)
	}
	checkChange("go.mod", protocol.Changed)
	if err := writeFileData("newFile", []byte("something"), wd.RelativeTo); err != nil {
		t.Fatal(err)
	}
	checkChange("newFile", protocol.Created)
	fp := wd.AbsPath("newFile")
	if err := os.Remove(fp); err != nil {
		t.Fatal(err)
	}
	checkChange("newFile", protocol.Deleted)
}

func TestSplitModuleVersionPath(t *testing.T) {
	tests := []struct {
		path                                string
		wantModule, wantVersion, wantSuffix string
	}{
		{"foo.com@v1.2.3/bar", "foo.com", "v1.2.3", "bar"},
		{"foo.com/module@v1.2.3/bar", "foo.com/module", "v1.2.3", "bar"},
		{"foo.com@v1.2.3", "foo.com", "v1.2.3", ""},
		{"std@v1.14.0", "std", "v1.14.0", ""},
		{"another/module/path", "another/module/path", "", ""},
	}

	for _, test := range tests {
		module, version, suffix := splitModuleVersionPath(test.path)
		if module != test.wantModule || version != test.wantVersion || suffix != test.wantSuffix {
			t.Errorf("splitModuleVersionPath(%q) =\n\t(%q, %q, %q)\nwant\n\t(%q, %q, %q)",
				test.path, module, version, suffix, test.wantModule, test.wantVersion, test.wantSuffix)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/fake/workdir_windows.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake

import (
	"errors"
	"syscall"
)

func init() {
	// constants copied from GOROOT/src/internal/syscall/windows/syscall_windows.go
	const (
		ERROR_LOCK_VIOLATION syscall.Errno = 33
	)

	isWindowsErrLockViolation = func(err error) bool {
		return errors.Is(err, ERROR_LOCK_VIOLATION)
	}
}


================================================
FILE: gopls/internal/test/integration/hover/hover_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package hover

import (
	"os"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

// TestIssue77675 verifies that hovering over a raw string literal containing
// Windows line endings (\r\n) does not cause an out-of-bounds panic.
func TestIssue77675(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.20

-- main.go --
package main

func _() {
    _ = ` + "`" + `foo

bar
baz` + "`" + `
}
`
	WithOptions(
		WindowsLineEndings(),
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Await(env.DoneWithOpen())
		loc := env.RegexpSearch("main.go", "baz()")
		content, l := env.Hover(loc)
		if !l.Empty() {
			t.Errorf("hover expect empty range got: %v", l)
		}
		if content != nil {
			t.Errorf("hover expect empty result got: %v", content)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/inlayhints/inlayhints_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package inlayhint

import (
	"os"
	"testing"

	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

func TestEnablingInlayHints(t *testing.T) {
	const workspace = `
-- go.mod --
module inlayHint.test
go 1.12
-- lib.go --
package lib
type Number int
const (
	Zero Number = iota
	One
	Two
)
`
	tests := []struct {
		label         string
		enabled       map[string]bool
		wantInlayHint bool
	}{
		{
			label:         "default",
			wantInlayHint: false,
		},
		{
			label:         "enable const",
			enabled:       map[string]bool{string(settings.ConstantValues): true},
			wantInlayHint: true,
		},
		{
			label:         "enable parameter names",
			enabled:       map[string]bool{string(settings.ParameterNames): true},
			wantInlayHint: false,
		},
	}
	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			WithOptions(
				Settings{
					"hints": test.enabled,
				},
			).Run(t, workspace, func(t *testing.T, env *Env) {
				env.OpenFile("lib.go")
				lens := env.InlayHints("lib.go")
				if gotInlayHint := len(lens) > 0; gotInlayHint != test.wantInlayHint {
					t.Errorf("got inlayHint: %t, want %t", gotInlayHint, test.wantInlayHint)
				}
			})
		})
	}
}


================================================
FILE: gopls/internal/test/integration/misc/addtest_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestAddTest is a basic test of interaction with the "gopls.add_test" code action.
func TestAddTest(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

import(
	"context"
)

func Foo(ctx context.Context, in string) string {return in}

-- a/a_test.go --
package a_test

import(
	"testing"
)

func TestExisting(t *testing.T) {}
`
	const want = `package a_test

import (
	"context"
	"testing"

	"example.com/a"
)

func TestExisting(t *testing.T) {}

func TestFoo(t *testing.T) {
	tests := []struct {
		name string // description of this test case
		// Named input parameters for target function.
		in   string
		want string
	}{
		// TODO: Add test cases.
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got := a.Foo(context.Background(), tt.in)
			// TODO: update the condition below to compare got with tt.want.
			if true {
				t.Errorf("Foo() = %v, want %v", got, tt.want)
			}
		})
	}
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		loc := env.RegexpSearch("a/a.go", "Foo")
		actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
		if err != nil {
			t.Fatalf("CodeAction: %v", err)
		}
		action, err := CodeActionByKind(actions, settings.AddTest)
		if err != nil {
			t.Fatal(err)
		}
		action, err = env.Editor.ResolveCodeAction(env.Ctx, action)
		if err != nil {
			t.Fatal(err)
		}

		// Execute the command.
		// Its side effect should be a single showDocument request.
		params := &protocol.ExecuteCommandParams{
			Command:   action.Command.Command,
			Arguments: action.Command.Arguments,
		}

		listen := env.Awaiter.ListenToShownDocuments()
		env.ExecuteCommand(params, nil)
		// Wait until we finish writing to the file.
		env.AfterChange()
		if got := env.BufferText("a/a_test.go"); got != want {
			t.Errorf("gopls.add_test returned unexpected diff (-want +got):\n%s", compare.Text(want, got))
		}

		got := listen()
		if len(got) != 1 {
			t.Errorf("gopls.add_test: got %d showDocument requests, want 1: %v", len(got), got)
		} else {
			if want := protocol.URI(env.Sandbox.Workdir.URI("a/a_test.go")); got[0].URI != want {
				t.Errorf("gopls.add_test: got showDocument requests for %v, want %v", got[0].URI, want)
			}

			// Pointing to the line of test function declaration.
			if want := (protocol.Range{
				Start: protocol.Position{
					Line: 11,
				},
				End: protocol.Position{
					Line: 11,
				},
			}); *got[0].Selection != want {
				t.Errorf("gopls.add_test: got showDocument requests selection for %v, want %v", *got[0].Selection, want)
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/call_hierarchy_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test for golang/go#49125
func TestCallHierarchy_Issue49125(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- p.go --
package pkg
`
	// TODO(rfindley): this could probably just be a marker test.
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		loc := env.RegexpSearch("p.go", "pkg")

		var params protocol.CallHierarchyPrepareParams
		params.TextDocument.URI = loc.URI
		params.Position = loc.Range.Start

		// Check that this doesn't panic.
		env.Editor.Server.PrepareCallHierarchy(env.Ctx, &params)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/codeactions_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"slices"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// This test exercises the filtering of code actions in generated files.
// Most code actions, being potential edits, are discarded, but
// some (GoTest, GoDoc) are pure queries, and so are allowed.
func TestCodeActionsInGeneratedFiles(t *testing.T) {
	const src = `
-- go.mod --
module example.com
go 1.19

-- src/a.go --
package a

func f() { g() }
func g() {}
-- gen/a.go --
// Code generated by hand; DO NOT EDIT.
package a

func f() { g() }
func g() {}

-- issue72742/a.go --
package main

func main(){
	fmt.Println("helloworld")
}
`

	Run(t, src, func(t *testing.T, env *Env) {
		check := func(filename string, re string, want []protocol.CodeActionKind) {
			env.OpenFile(filename)
			loc := env.RegexpSearch(filename, re)
			actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
			if err != nil {
				t.Fatal(err)
			}

			type kinds = []protocol.CodeActionKind
			got := make(kinds, 0)
			for _, act := range actions {
				got = append(got, act.Kind)
			}

			if diff := cmp.Diff(want, got); diff != "" {
				t.Errorf("%s: unexpected CodeActionKinds: (-want +got):\n%s",
					filename, diff)
				t.Log(actions)
			}
		}

		check("src/a.go", `g\(\)`, []protocol.CodeActionKind{
			settings.AddTest,
			settings.GoAssembly,
			settings.GoDoc,
			settings.GoFreeSymbols,
			settings.GoSplitPackage,
			settings.GoToggleCompilerOptDetails,
			settings.RefactorInlineCall,
			settings.GoplsDocFeatures,
		})

		check("gen/a.go", `g\(\)`, []protocol.CodeActionKind{
			settings.GoAssembly,
			settings.GoDoc,
			settings.GoFreeSymbols,
			settings.GoSplitPackage,
			settings.GoToggleCompilerOptDetails,
			settings.GoplsDocFeatures,
		})

		check("issue72742/a.go", `fmt`, []protocol.CodeActionKind{
			settings.OrganizeImports,
			settings.AddTest,
			settings.GoAssembly,
			settings.GoDoc,
			settings.GoFreeSymbols,
			settings.GoSplitPackage,
			settings.GoToggleCompilerOptDetails,
			settings.GoplsDocFeatures,
		})
	})
}

// Test refactor.inline.call is not included in automatically triggered code action
// unless users want refactoring.
//
// (The mechanism behind this behavior has changed. It was added when
// we used to interpret CodeAction(Only=[]) as "all kinds", which was
// a distracting nuisance (too many lightbulbs); this was fixed by
// adding special logic to refactor.inline.call to respect the trigger
// kind; but now we do this for all actions (for similar reasons) and
// interpret Only=[] as Only=[quickfix] unless triggerKind=invoked;
// except that the test client always requests CodeAction(Only=[""]).
// So, we should remove the special logic from refactorInlineCall
// and vary the Only parameter used by the test client.)
func TestVSCodeIssue65167(t *testing.T) {
	const vim1 = `package main

func main() {
	Func()  // range to be selected
}

func Func() int { return 0 }
`

	Run(t, "", func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", vim1)
		for _, trigger := range []protocol.CodeActionTriggerKind{
			protocol.CodeActionUnknownTrigger,
			protocol.CodeActionInvoked,
			protocol.CodeActionAutomatic,
		} {
			t.Run(fmt.Sprintf("trigger=%v", trigger), func(t *testing.T) {
				for _, selectedRange := range []bool{false, true} {
					t.Run(fmt.Sprintf("range=%t", selectedRange), func(t *testing.T) {
						loc := env.RegexpSearch("main.go", "Func")
						if !selectedRange {
							// assume the cursor is placed at the beginning of `Func`, so end==start.
							loc.Range.End = loc.Range.Start
						}
						actions := env.CodeAction(loc, nil, trigger)
						want := trigger != protocol.CodeActionAutomatic || selectedRange
						if got := slices.ContainsFunc(actions, func(act protocol.CodeAction) bool {
							return act.Kind == settings.RefactorInlineCall
						}); got != want {
							t.Errorf("got refactor.inline.call = %t, want %t", got, want)
						}
					})
				}
			})
		}
	})
}

// TestDescendingRange isn't really a test of CodeAction at all: it
// merely tests the response of the server to any (start, end) range
// that is descending. See #74394.
func TestDescendingRange(t *testing.T) {
	const src = `
-- go.mod --
module example.com
go 1.19

-- a/a.go --
package a
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		loc := env.RegexpSearch("a/a.go", "package")
		rng := &loc.Range
		rng.Start, rng.End = rng.End, rng.Start
		_, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
		got, wantSubstr := fmt.Sprint(err), "start (offset 7) > end (offset 0)"
		if !strings.Contains(got, wantSubstr) {
			t.Fatalf("CodeAction error: got %q, want substring %q", got, wantSubstr)
		}
	})
}

// TestIssue76235 is a regression test for a crash in CodeAction
// (refactor.extract.variable-all). It can't be a marker test since
// the fixed behavior is a no-op: no code actions, no crash.
func TestIssue76235(t *testing.T) {
	const src = `
-- a/a.go --
package a; func f([3]int)
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		loc := env.RegexpSearch("a/a.go", "3")
		env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger) // ignore error
	})
}


================================================
FILE: gopls/internal/test/integration/misc/compileropt_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"runtime"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestCompilerOptDetails exercises the "{Show,Hide} compiler optimization details" code action.
func TestCompilerOptDetails(t *testing.T) {
	if runtime.GOOS == "android" {
		t.Skipf("the compiler optimization details code action doesn't work on Android")
	}

	const mod = `
-- go.mod --
module mod.com

go 1.18

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println(42)
}
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		actions := env.CodeActionForFile("main.go", nil)

		// Execute the "Show compiler optimization details" command.
		docAction, err := CodeActionByKind(actions, settings.GoToggleCompilerOptDetails)
		if err != nil {
			t.Fatal(err)
		}

		params := &protocol.ExecuteCommandParams{
			Command:   docAction.Command.Command,
			Arguments: docAction.Command.Arguments,
		}
		env.ExecuteCommand(params, nil)

		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromToggleCompilerOptDetails), 1, true),
			Diagnostics(
				ForFile("main.go"),
				AtPosition("main.go", 5, 13), // (LSP coordinates)
				WithMessage("42 escapes"),
				WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
			),
		)

		// Diagnostics should be reported even on unsaved
		// edited buffers, thanks to the magic of overlays.
		env.SetBufferContent("main.go", `
package main
func main() { _ = f }
func f(x int) *int { return &x }`)
		env.AfterChange(Diagnostics(
			ForFile("main.go"),
			WithMessage("x escapes"),
			WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
		))

		// Toggle the flag again so now it should be off.
		env.ExecuteCommand(params, nil)
		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromToggleCompilerOptDetails), 2, true),
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// TestCompilerOptDetails_perDirectory exercises that the "want
// optimization details" flag has per-directory cardinality.
func TestCompilerOptDetails_perDirectory(t *testing.T) {
	if runtime.GOOS == "android" {
		t.Skipf("the compiler optimization details code action doesn't work on Android")
	}

	const mod = `
-- go.mod --
module mod.com
go 1.18

-- a/a.go --
package a

func F(x int) any { return &x }

-- a/a_test.go --
package a

func G(x int) any { return &x }

-- a/a_x_test.go --
package a_test

func H(x int) any { return &x }
`

	Run(t, mod, func(t *testing.T, env *Env) {
		// toggle executes the "Toggle compiler optimization details"
		// command within a file, and asserts that it has the specified title.
		toggle := func(filename, wantTitle string) {
			env.OpenFile(filename)
			actions := env.CodeActionForFile(filename, nil)

			docAction, err := CodeActionByKind(actions, settings.GoToggleCompilerOptDetails)
			if err != nil {
				t.Fatal(err)
			}
			if docAction.Title != wantTitle {
				t.Errorf("CodeAction.Title = %q, want %q", docAction.Title, wantTitle)
			}
			params := &protocol.ExecuteCommandParams{
				Command:   docAction.Command.Command,
				Arguments: docAction.Command.Arguments,
			}
			env.ExecuteCommand(params, nil)
		}

		// Show diagnostics for directory a/ from one file.
		// Diagnostics are reported for all three packages.
		toggle("a/a.go", `Show compiler optimization details for "a"`)
		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromToggleCompilerOptDetails), 1, true),
			Diagnostics(
				ForFile("a/a.go"),
				AtPosition("a/a.go", 2, 7),
				WithMessage("x escapes to heap"),
				WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
			),
			Diagnostics(
				ForFile("a/a_test.go"),
				AtPosition("a/a_test.go", 2, 7),
				WithMessage("x escapes to heap"),
				WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
			),
			Diagnostics(
				ForFile("a/a_x_test.go"),
				AtPosition("a/a_x_test.go", 2, 7),
				WithMessage("x escapes to heap"),
				WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
			),
		)

		// Hide diagnostics for the directory from a different file.
		// All diagnostics disappear.
		toggle("a/a_test.go", `Hide compiler optimization details for "a"`)
		env.OnceMet(
			CompletedWork(server.DiagnosticWorkTitle(server.FromToggleCompilerOptDetails), 2, true),
			NoDiagnostics(ForFile("a/a.go")),
			NoDiagnostics(ForFile("a/a_test.go")),
			NoDiagnostics(ForFile("a/a_x_test.go")),
		)
	})
}

// TestCompilerOptDetails_config exercises that the "want optimization
// details" flag honors the "annotation" configuration setting.
func TestCompilerOptDetails_config(t *testing.T) {
	if runtime.GOOS == "android" {
		t.Skipf("the compiler optimization details code action doesn't work on Android")
	}

	const mod = `
-- go.mod --
module mod.com
go 1.18

-- a/a.go --
package a

func F(x int) any { return &x         } // escape(x escapes to heap)
func G()          { defer func(){} () } // cannotInlineFunction(unhandled op DEFER)
`

	for _, escape := range []bool{true, false} {
		WithOptions(
			Settings{"annotations": map[string]any{"inline": true, "escape": escape}},
		).Run(t, mod, func(t *testing.T, env *Env) {
			env.OpenFile("a/a.go")
			actions := env.CodeActionForFile("a/a.go", nil)

			docAction, err := CodeActionByKind(actions, settings.GoToggleCompilerOptDetails)
			if err != nil {
				t.Fatal(err)
			}
			params := &protocol.ExecuteCommandParams{
				Command:   docAction.Command.Command,
				Arguments: docAction.Command.Arguments,
			}
			env.ExecuteCommand(params, nil)

			env.OnceMet(
				CompletedWork(server.DiagnosticWorkTitle(server.FromToggleCompilerOptDetails), 1, true),
				cond(escape, Diagnostics, NoDiagnostics)(
					ForFile("a/a.go"),
					AtPosition("a/a.go", 2, 7),
					WithMessage("x escapes to heap"),
					WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
				),
				Diagnostics(
					ForFile("a/a.go"),
					AtPosition("a/a.go", 3, 5),
					WithMessage("cannotInlineFunction(unhandled op DEFER)"),
					WithSeverityTags("optimizer details", protocol.SeverityInformation, nil),
				),
			)
		})
	}
}

func cond[T any](cond bool, x, y T) T {
	if cond {
		return x
	} else {
		return y
	}
}


================================================
FILE: gopls/internal/test/integration/misc/configuration_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"

	"golang.org/x/tools/internal/testenv"
)

// Test that enabling and disabling produces the expected results of showing
// and hiding staticcheck analysis results.
func TestChangeConfiguration(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

import "errors"

// FooErr should be called ErrFoo (ST1012)
var FooErr = errors.New("foo")
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
		cfg := env.Editor.Config()
		cfg.Settings = map[string]any{
			"staticcheck": true,
		}
		env.ChangeConfiguration(cfg)
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "var (FooErr)")),
		)
	})
}

func TestIdenticalConfiguration(t *testing.T) {
	// This test checks that changing configuration does not cause views to be
	// recreated if there is no configuration change.
	const files = `
-- a.go --
package p

func _() {
	var x *int
	y := *x
	_ = y
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		// Sanity check: before disabling the nilness analyzer, we should have a
		// diagnostic for the nil dereference.
		env.OpenFile("a.go")
		env.AfterChange(
			Diagnostics(
				ForFile("a.go"),
				WithMessage("nil dereference"),
			),
		)

		// Collect the view ID before changing configuration.
		viewID := func() string {
			t.Helper()
			views := env.Views()
			if len(views) != 1 {
				t.Fatalf("got %d views, want 1", len(views))
			}
			return views[0].ID
		}
		before := viewID()

		// Now disable the nilness analyzer.
		cfg := env.Editor.Config()
		cfg.Settings = map[string]any{
			"analyses": map[string]any{
				"nilness": false,
			},
		}

		// This should cause the diagnostic to disappear...
		env.ChangeConfiguration(cfg)
		env.AfterChange(
			NoDiagnostics(),
		)
		// ...and we should be on the second view.
		after := viewID()
		if after == before {
			t.Errorf("after configuration change, got view %q (same as before), want new view", after)
		}

		// Now change configuration again, this time with the same configuration as
		// before. We should still have no diagnostics...
		env.ChangeConfiguration(cfg)
		env.AfterChange(
			NoDiagnostics(),
		)
		// ...and we should still be on the second view.
		if got := viewID(); got != after {
			t.Errorf("after second configuration change, got view %q, want %q", got, after)
		}
	})
}

// Test that clients can configure per-workspace configuration, which is
// queried via the scopeURI of a workspace/configuration request.
// (this was broken in golang/go#65519).
func TestWorkspaceConfiguration(t *testing.T) {
	const files = `
-- go.mod --
module example.com/config

go 1.18

-- a/a.go --
package a

import "example.com/config/b"

func _() {
	_ = b.B{2}
}

-- b/b.go --
package b

type B struct {
	F int
}
`

	WithOptions(
		WorkspaceFolders("a"),
		FolderSettings{
			"a": {
				"analyses": map[string]bool{
					"composites": false,
				},
			},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(NoDiagnostics())
	})
}

// TestMajorOptionsChange is like TestChangeConfiguration, but modifies an
// an open buffer before making a major (but inconsequential) change that
// causes gopls to recreate the view.
//
// Gopls should not get confused about buffer content when recreating the view.
func TestMajorOptionsChange(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

import "errors"

var ErrFoo = errors.New("foo")
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		// Introduce a staticcheck diagnostic. It should be detected when we enable
		// staticcheck later.
		env.RegexpReplace("a/a.go", "ErrFoo", "FooErr")
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
		cfg := env.Editor.Config()
		// Any change to environment recreates the view, but this should not cause
		// gopls to get confused about the content of a/a.go: we should get the
		// staticcheck diagnostic below.
		cfg.Env = map[string]string{
			"AN_ARBITRARY_VAR": "FOO",
		}
		cfg.Settings = map[string]any{
			"staticcheck": true,
		}
		env.ChangeConfiguration(cfg)
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "var (FooErr)")),
		)
	})
}

func TestStaticcheckWarning(t *testing.T) {
	// Note: keep this in sync with TestChangeConfiguration.
	testenv.SkipAfterGo1Point(t, 19)

	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

import "errors"

// FooErr should be called ErrFoo (ST1012)
var FooErr = errors.New("foo")
`

	WithOptions(
		Settings{"staticcheck": true},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			ShownMessage("staticcheck is not supported"),
		)
	})
}

func TestDeprecatedSettings(t *testing.T) {
	WithOptions(
		Settings{
			"experimentalUseInvalidMetadata": true,
			"experimentalWatchedFileDelay":   "1s",
			"experimentalWorkspaceModule":    true,
			"tempModfile":                    true,
			"allowModfileModifications":      true,
			"allowImplicitNetworkAccess":     true,
		},
	).Run(t, "", func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			ShownMessage("experimentalWorkspaceModule"),
			ShownMessage("experimentalUseInvalidMetadata"),
			ShownMessage("experimentalWatchedFileDelay"),
			ShownMessage("tempModfile"),
			ShownMessage("allowModfileModifications"),
			ShownMessage("allowImplicitNetworkAccess"),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/debugserver_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"net/http"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestStartDebugging(t *testing.T) {
	WithOptions(
		Modes(Forwarded),
	).Run(t, "", func(t *testing.T, env *Env) {
		args, err := command.MarshalArgs(command.DebuggingArgs{})
		if err != nil {
			t.Fatal(err)
		}
		params := &protocol.ExecuteCommandParams{
			Command:   command.StartDebugging.String(),
			Arguments: args,
		}
		var result command.DebuggingResult
		env.ExecuteCommand(params, &result)
		if got, want := len(result.URLs), 2; got != want {
			t.Fatalf("got %d urls, want %d; urls: %#v", got, want, result.URLs)
		}
		for i, u := range result.URLs {
			resp, err := http.Get(u)
			if err != nil {
				t.Errorf("getting url #%d (%q): %v", i, u, err)
				continue
			}
			defer resp.Body.Close()
			if got, want := resp.StatusCode, http.StatusOK; got != want {
				t.Errorf("debug server #%d returned HTTP %d, want %d", i, got, want)
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/definition_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

const internalDefinition = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println(message)
}
-- const.go --
package main

const message = "Hello World."
`

func TestGoToInternalDefinition(t *testing.T) {
	Run(t, internalDefinition, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", "message"))
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "const.go"; name != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
		if want := env.RegexpSearch("const.go", "message"); loc != want {
			t.Errorf("Definition: got location %v, want %v", loc, want)
		}
	})
}

const linknameDefinition = `
-- go.mod --
module mod.com

-- upper/upper.go --
package upper

import (
	_ "unsafe"

	_ "mod.com/middle"
)

//go:linkname foo mod.com/lower.bar
func foo() string

-- middle/middle.go --
package middle

import (
	_ "mod.com/lower"
)

-- lower/lower.s --

-- lower/lower.go --
package lower

func bar() string {
	return "bar as foo"
}`

func TestGoToLinknameDefinition(t *testing.T) {
	Run(t, linknameDefinition, func(t *testing.T, env *Env) {
		env.OpenFile("upper/upper.go")

		// Jump from directives 2nd arg.
		start := env.RegexpSearch("upper/upper.go", `lower.bar`)
		loc := env.FirstDefinition(start)
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "lower/lower.go"; name != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
		if want := env.RegexpSearch("lower/lower.go", `bar`); loc != want {
			t.Errorf("Definition: got position %v, want %v", loc, want)
		}
	})
}

const linknameDefinitionReverse = `
-- go.mod --
module mod.com

-- upper/upper.s --

-- upper/upper.go --
package upper

import (
	_ "mod.com/middle"
)

func foo() string

-- middle/middle.go --
package middle

import (
	_ "mod.com/lower"
)

-- lower/lower.go --
package lower

import _ "unsafe"

//go:linkname bar mod.com/upper.foo
func bar() string {
	return "bar as foo"
}`

func TestGoToLinknameDefinitionInReverseDep(t *testing.T) {
	Run(t, linknameDefinitionReverse, func(t *testing.T, env *Env) {
		env.OpenFile("lower/lower.go")

		// Jump from directives 2nd arg.
		start := env.RegexpSearch("lower/lower.go", `upper.foo`)
		loc := env.FirstDefinition(start)
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "upper/upper.go"; name != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
		if want := env.RegexpSearch("upper/upper.go", `foo`); loc != want {
			t.Errorf("Definition: got position %v, want %v", loc, want)
		}
	})
}

// The linkname directive connects two packages not related in the import graph.
const linknameDefinitionDisconnected = `
-- go.mod --
module mod.com

-- a/a.go --
package a

import (
	_ "unsafe"
)

//go:linkname foo mod.com/b.bar
func foo() string

-- b/b.go --
package b

func bar() string {
	return "bar as foo"
}`

func TestGoToLinknameDefinitionDisconnected(t *testing.T) {
	Run(t, linknameDefinitionDisconnected, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		// Jump from directives 2nd arg.
		start := env.RegexpSearch("a/a.go", `b.bar`)
		loc := env.FirstDefinition(start)
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "b/b.go"; name != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
		if want := env.RegexpSearch("b/b.go", `bar`); loc != want {
			t.Errorf("Definition: got position %v, want %v", loc, want)
		}
	})
}

const stdlibDefinition = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Printf()
}`

func TestGoToStdlibDefinition_Issue37045(t *testing.T) {
	Run(t, stdlibDefinition, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", `fmt.(Printf)`))
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if got, want := path.Base(name), "print.go"; got != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
		env.OpenFile(name)

		// Test that we can jump to definition from outside our workspace.
		// See golang.org/issues/37045.
		newLoc := env.FirstDefinition(loc)
		newName := env.Sandbox.Workdir.URIToPath(newLoc.URI)
		if newName != name {
			t.Errorf("Definition is not idempotent: got %q, want %q", newName, name)
		}
		if newLoc != loc {
			t.Errorf("Definition is not idempotent: got %v, want %v", newLoc, loc)
		}
	})
}

func TestUnexportedStdlib_Issue40809(t *testing.T) {
	Run(t, stdlibDefinition, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", `fmt.(Printf)`))
		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		env.OpenFile(name)

		loc = env.RegexpSearch(name, `:=\s*(newPrinter)\(\)`)

		// Check that we can find references on a reference
		refs := env.References(loc)
		if len(refs) < 5 {
			t.Errorf("expected 5+ references to newPrinter, found: %#v", refs)
		}

		loc = env.FirstDefinition(loc)
		content, _ := env.Hover(loc)
		if !strings.Contains(content.Value, "newPrinter") {
			t.Fatal("definition of newPrinter went to the incorrect place")
		}
		// And on the definition too.
		refs = env.References(loc)
		if len(refs) < 5 {
			t.Errorf("expected 5+ references to newPrinter, found: %#v", refs)
		}
	})
}

// Test the hover on an error's Error function.
// This can't be done via the marker tests because Error is a builtin.
func TestHoverOnError(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
	var err error
	err.Error()
}`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		content, _ := env.Hover(env.RegexpSearch("main.go", "Error"))
		if content == nil {
			t.Fatalf("nil hover content for Error")
		}
		want := "```go\nfunc (error).Error() string\n```"
		if content.Value != want {
			t.Fatalf("hover failed:\n%s", compare.Text(want, content.Value))
		}
	})
}

func TestImportShortcut(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {}
`
	for _, tt := range []struct {
		wantLinks      int
		importShortcut string
	}{
		{1, "Link"},
		{0, "Definition"},
		{1, "Both"},
	} {
		t.Run(tt.importShortcut, func(t *testing.T) {
			WithOptions(
				Settings{"importShortcut": tt.importShortcut},
			).Run(t, mod, func(t *testing.T, env *Env) {
				env.OpenFile("main.go")
				loc := env.FirstDefinition(env.RegexpSearch("main.go", `"fmt"`))
				if loc == (protocol.Location{}) {
					t.Fatalf("expected definition, got none")
				}
				links := env.DocumentLink("main.go")
				if len(links) != tt.wantLinks {
					t.Fatalf("expected %v links, got %v", tt.wantLinks, len(links))
				}
			})
		})
	}
}

// Test for golang/go#47825.
func TestImportTestVariant(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- client/test/role.go --
package test

import _ "mod.com/client"

type RoleSetup struct{}
-- client/client_role_test.go --
package client_test

import (
	"testing"
	_ "mod.com/client"
	ctest "mod.com/client/test"
)

func TestClient(t *testing.T) {
	_ = ctest.RoleSetup{}
}
-- client/client_test.go --
package client

import "testing"

func TestClient(t *testing.T) {}
-- client.go --
package client
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("client/client_role_test.go")
		env.FirstDefinition(env.RegexpSearch("client/client_role_test.go", "RoleSetup"))
	})
}

// This test exercises a crashing pattern from golang/go#49223.
func TestGoToCrashingDefinition_Issue49223(t *testing.T) {
	Run(t, "", func(t *testing.T, env *Env) {
		params := &protocol.DefinitionParams{}
		params.TextDocument.URI = protocol.DocumentURI("fugitive%3A///Users/user/src/mm/ems/.git//0/pkg/domain/treasury/provider.go")
		params.Position.Character = 18
		params.Position.Line = 0
		env.Editor.Server.Definition(env.Ctx, params) // ignore error
	})
}

// TestVendoringInvalidatesMetadata ensures that gopls uses the
// correct metadata even after an external 'go mod vendor' command
// causes packages to move; see issue #55995.
// See also TestImplementationsInVendor, which tests the same fix.
func TestVendoringInvalidatesMetadata(t *testing.T) {
	t.Skip("golang/go#56169: file watching does not capture vendor dirs")

	const proxy = `
-- other.com/b@v1.0.0/go.mod --
module other.com/b
go 1.14

-- other.com/b@v1.0.0/b.go --
package b
const K = 0
`
	const src = `
-- go.mod --
module example.com/a
go 1.14
require other.com/b v1.0.0

-- a.go --
package a
import "other.com/b"
const _ = b.K

`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
		Modes(Default), // fails in 'experimental' mode
	).Run(t, src, func(t *testing.T, env *Env) {
		// Enable to debug go.sum mismatch, which may appear as
		// "module lookup disabled by GOPROXY=off", confusingly.
		if false {
			env.DumpGoSum(".")
		}

		env.OpenFile("a.go")
		refLoc := env.RegexpSearch("a.go", "K") // find "b.K" reference

		// Initially, b.K is defined in the module cache.
		gotLoc := env.FirstDefinition(refLoc)
		gotFile := env.Sandbox.Workdir.URIToPath(gotLoc.URI)
		wantCache := filepath.ToSlash(env.Sandbox.GOPATH()) + "/pkg/mod/other.com/b@v1.0.0/b.go"
		if gotFile != wantCache {
			t.Errorf("Definition, before: got file %q, want %q", gotFile, wantCache)
		}

		// Run 'go mod vendor' outside the editor.
		env.RunGoCommand("mod", "vendor")

		// Synchronize changes to watched files.
		env.Await(env.DoneWithChangeWatchedFiles())

		// Now, b.K is defined in the vendor tree.
		gotLoc = env.FirstDefinition(refLoc)
		wantVendor := "vendor/other.com/b/b.go"
		if gotFile != wantVendor {
			t.Errorf("Definition, after go mod vendor: got file %q, want %q", gotFile, wantVendor)
		}

		// Delete the vendor tree.
		if err := os.RemoveAll(env.Sandbox.Workdir.AbsPath("vendor")); err != nil {
			t.Fatal(err)
		}
		// Notify the server of the deletion.
		if err := env.Sandbox.Workdir.CheckForFileChanges(env.Ctx); err != nil {
			t.Fatal(err)
		}

		// Synchronize again.
		env.Await(env.DoneWithChangeWatchedFiles())

		// b.K is once again defined in the module cache.
		gotLoc = env.FirstDefinition(gotLoc)
		gotFile = env.Sandbox.Workdir.URIToPath(gotLoc.URI)
		if gotFile != wantCache {
			t.Errorf("Definition, after rm -rf vendor: got file %q, want %q", gotFile, wantCache)
		}
	})
}

const embedDefinition = `
-- go.mod --
module mod.com

-- main.go --
package main

import (
	"embed"
)

//go:embed *.txt
var foo embed.FS

func main() {}

-- skip.sql --
SKIP

-- foo.txt --
FOO

-- skip.bat --
SKIP
`

func TestEmbedDefinition(t *testing.T) {
	Run(t, embedDefinition, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")

		start := env.RegexpSearch("main.go", `\*.txt`)
		loc := env.FirstDefinition(start)

		name := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "foo.txt"; name != want {
			t.Errorf("Definition: got file %q, want %q", name, want)
		}
	})
}

func TestDefinitionOfErrorErrorMethod(t *testing.T) {
	const src = `Regression test for a panic in definition of error.Error (of course).
golang/go#64086

-- go.mod --
module mod.com
go 1.18

-- a.go --
package a

func _(err error) {
	_ = err.Error()
}

`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		start := env.RegexpSearch("a.go", `Error`)
		loc := env.FirstDefinition(start)

		if !strings.HasSuffix(string(loc.URI), "builtin.go") {
			t.Errorf("Definition(err.Error) = %#v, want builtin.go", loc)
		}
	})
}

func TestAssemblyDefinition(t *testing.T) {
	// This test cannot be expressed as a marker test because
	// the expect package ignores markers (@loc) within a .s file.
	const src = `
-- go.mod --
module mod.com

-- foo_darwin_arm64.s --

// assembly implementation
TEXT ·foo(SB),NOSPLIT,$0
	RET

-- a.go --
//go:build darwin && arm64

package a

// Go declaration
func foo(int) int

var _ = foo(123) // call
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		locString := func(loc protocol.Location) string {
			return fmt.Sprintf("%s:%s", loc.URI.Base(), loc.Range)
		}

		// Definition at the call"foo(123)" takes us to the Go declaration.
		callLoc := env.RegexpSearch("a.go", regexp.QuoteMeta("foo(123)"))
		declLoc := env.FirstDefinition(callLoc)
		if got, want := locString(declLoc), "a.go:5:5-5:8"; got != want {
			t.Errorf("Definition(call): got %s, want %s", got, want)
		}

		// Definition a second time takes us to the assembly implementation.
		implLoc := env.FirstDefinition(declLoc)
		if got, want := locString(implLoc), "foo_darwin_arm64.s:2:6-2:9"; got != want {
			t.Errorf("Definition(go decl): got %s, want %s", got, want)
		}
	})
}

func TestPackageKeyInvalidationAfterSave(t *testing.T) {
	// This test is a little subtle, but catches a bug that slipped through
	// testing of https://go.dev/cl/614165, which moved active packages to the
	// packageHandle.
	//
	// The bug was that after a format-and-save operation, the save marks the
	// package as dirty but doesn't change its identity. In other words, this is
	// the sequence of change:
	//
	//  S_0 --format--> S_1 --save--> S_2
	//
	// A package is computed on S_0, invalidated in S_1 and immediately
	// invalidated again in S_2. Due to an invalidation bug, the validity of the
	// package from S_0 was checked by comparing the identical keys of S_1 and
	// S_2, and so the stale package from S_0 was marked as valid.
	const src = `
-- go.mod --
module mod.com

-- a.go --
package a

func Foo() {
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		fooLoc := env.RegexpSearch("a.go", "()Foo")
		loc0 := env.FirstDefinition(fooLoc)

		// Insert a space that will be removed by formatting.
		env.EditBuffer("a.go", protocol.TextEdit{
			Range:   fooLoc.Range,
			NewText: " ",
		})
		env.SaveBuffer("a.go") // reformats the file before save
		env.AfterChange()
		loc1 := env.FirstDefinition(env.RegexpSearch("a.go", "Foo"))
		if diff := cmp.Diff(loc0, loc1); diff != "" {
			t.Errorf("mismatching locations (-want +got):\n%s", diff)
		}
	})
}

func TestCommentDefinition_Issue69616(t *testing.T) {
	// This test exercises a few edge cases discovered by telemetry in
	// golang/go#69616, namely situations where a parsed Go file might
	// not have an associated scope in the package types.Info.
	//
	// The files below set up two types of edge cases:
	//  - a 'compiled' Go file that isn't actually type-checked, because it has
	//    the wrong package name
	//  - a non-compiled Go file (unsafe.go).
	const src = `
-- go.mod --
module mod.com

go 1.21
-- cmd/main.go --
package main

import "unsafe"

var _  = unsafe.Offsetof

func Foo() {}
-- cmd/x.go --
package x

// Bar is like [Foo]
func Bar() {}
`

	Run(t, src, func(t *testing.T, env *Env) {
		// First, check that we don't produce a crash or bug when
		// finding definitions in a 'compiled' go file that isn't actually type
		// checked.
		env.OpenFile("cmd/x.go")
		_, _ = env.Editor.Definitions(env.Ctx, env.RegexpSearch("cmd/x.go", "()Foo"))

		// Next, go to the unsafe package, and find the doc link to [Sizeof].
		// It will also fail to resolve, because unsafe.go isn't compiled, but
		// again should not panic or result in a bug.
		env.OpenFile("cmd/main.go")
		loc := env.FirstDefinition(env.RegexpSearch("cmd/main.go", `unsafe\.(Offsetof)`))
		unsafePath := loc.URI.Path()
		env.OpenFile(unsafePath)
		_, _ = env.Editor.Definitions(env.Ctx,
			env.RegexpSearch(unsafePath, `\[()Sizeof\]`))
	})
}
func TestUndefinedLabel_Issue76625(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.22
-- a.go --
package a

func UndefinedLabel() {
	for i := range 10 {
		if i > 2 {
			goto undefinedLabel
		}
	}
}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		expectedErr := "undefined label"
		gotoUndefined := env.RegexpSearch("a.go", `goto`)
		_, err := env.Editor.Definitions(env.Ctx, gotoUndefined)
		if err == nil {
			t.Fatalf("request succeeded unexpectedly, want error %s", err)
		}
		if !strings.Contains(err.Error(), expectedErr) {
			t.Fatalf("received unexpected error message %s, want %s", err, expectedErr)
		}
	})

}

func TestDefinition_embedSeparator(t *testing.T) {
	// This test checks that Definition on a //go:embed glob pattern reports
	// the location of the (first) matching file. It is a regression test for
	// a path-separator bug on Windows (https://go.dev/issue/77131).
	//
	// It can't be expressed as a marker test because it would require
	// a @def marker within a //go:embed directive.
	const src = `
-- go.mod --
module example.com
go 1.22

-- a/subdir/embed.txt --
hello

-- a/a.go --
package a

import _ "embed"

//go:embed subdir/embed.txt
var _ string
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		loc := env.FirstDefinition(env.RegexpSearch("a/a.go", "subdir"))
		got := fileLocations(env, []protocol.Location{loc})
		want := []string{"a/subdir/embed.txt:1"}
		if !reflect.DeepEqual(got, want) {
			t.Errorf("Definition at 'subdir' returned %v, want %v", got, want)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/embed_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestMissingPatternDiagnostic(t *testing.T) {
	const files = `
-- go.mod --
module example.com
-- x.go --
package x

import (
	_ "embed"
)

// Issue 47436
func F() {}

//go:embed NONEXISTENT
var Foo string
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("x.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("x.go", `NONEXISTENT`),
				WithMessage("no matching files found"),
			),
		)
		env.RegexpReplace("x.go", `NONEXISTENT`, "x.go")
		env.AfterChange(NoDiagnostics(ForFile("x.go")))
	})
}


================================================
FILE: gopls/internal/test/integration/misc/extract_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"

	"golang.org/x/tools/gopls/internal/protocol"
)

func TestExtractFunction(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func Foo() int {
	a := 5
	return a
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.RegexpSearch("main.go", `a := 5\n.*return a`)
		actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
		if err != nil {
			t.Fatal(err)
		}

		// Find the extract function code action.
		var extractFunc *protocol.CodeAction
		for _, action := range actions {
			if action.Kind == settings.RefactorExtractFunction {
				extractFunc = &action
				break
			}
		}
		if extractFunc == nil {
			t.Fatal("could not find extract function action")
		}

		env.ApplyCodeAction(*extractFunc)
		want := `package main

func Foo() int {
	return newFunction()
}

func newFunction() int {
	a := 5
	return a
}
`
		if got := env.BufferText("main.go"); got != want {
			t.Fatalf("TestExtractFunction failed:\n%s", compare.Text(want, got))
		}
	})
}

func TestExtractLabel(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func Foo(x []int) int {
	var i int
	for i = range x {
		if x[i] == 10 {
			goto found
		}
	}
	panic("not found")
found:

	if i < 2 {
	}
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.RegexpSearch("main.go", `(?s)for.*found:`)
		actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
		if err != nil {
			t.Fatal(err)
		}

		// Find the extract function code action.
		var extractFunc *protocol.CodeAction
		for _, action := range actions {
			if action.Kind == settings.RefactorExtractFunction {
				extractFunc = &action
				break
			}
		}
		if extractFunc == nil {
			t.Fatal("could not find extract function action")
		}

		env.ApplyCodeAction(*extractFunc)
		want := `package main

func Foo(x []int) int {
	var i int
	newFunction(i, x)

	if i < 2 {
	}
}

func newFunction(i int, x []int) {
	for i = range x {
		if x[i] == 10 {
			goto found
		}
	}
	panic("not found")
found:
}
`
		if got := env.BufferText("main.go"); got != want {
			t.Fatalf("TestExtractlabel failed:\n%s", compare.Text(want, got))
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/failures_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// This is a slight variant of TestHoverOnError in definition_test.go
// that includes a line directive, which makes no difference since
// gopls ignores line directives.
func TestHoverFailure(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- a.y --
DWIM(main)

-- main.go --
//line a.y:1
package main

func main() {
	var err error
	err.Error()
}`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		content, _ := env.Hover(env.RegexpSearch("main.go", "Error"))
		if content == nil {
			t.Fatalf("Hover('Error') returned nil")
		}
		want := "```go\nfunc (error).Error() string\n```"
		if content.Value != want {
			t.Fatalf("wrong Hover('Error') content:\n%s", compare.Text(want, content.Value))
		}
	})
}

// This test demonstrates a case where gopls is not at all confused by
// line directives, because it completely ignores them.
func TestFailingDiagnosticClearingOnEdit(t *testing.T) {
	// badPackageDup contains a duplicate definition of the 'A' const.
	// This is a minor variant of TestDiagnosticClearingOnEdit from
	// diagnostics_test.go, with a line directive, which makes no difference.
	const badPackageDup = `
-- go.mod --
module mod.com

go 1.12
-- a.go --
package consts

const A = 1
-- b.go --
package consts
//line gen.go:5
const A = 2
`

	Run(t, badPackageDup, func(t *testing.T, env *Env) {
		env.OpenFile("b.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("b.go", `A = 2`), WithMessage("A redeclared")),
			Diagnostics(env.AtRegexp("a.go", `A = 1`), WithMessage("other declaration")),
		)

		// Fix the error by editing the const name A in b.go to `B`.
		env.RegexpReplace("b.go", "(A) = 2", "B")
		env.AfterChange(
			NoDiagnostics(ForFile("a.go")),
			NoDiagnostics(ForFile("b.go")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/filecache_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/filecache"
	"golang.org/x/tools/gopls/internal/test/integration"
)

func TestMaxFileCacheBytes(t *testing.T) {
	before := filecache.SetBudget(-1)
	defer filecache.SetBudget(before)

	// Use a value large enough to ensure there are no
	// side effects, as file cache GC is global.
	const budget int64 = 50e9 // 50GB

	integration.WithOptions(
		integration.Settings(map[string]any{
			"maxFileCacheBytes": budget,
		}),
	).Run(t, "", func(t *testing.T, env *integration.Env) {
		// Verify that budget is set.
		if got := filecache.SetBudget(-1); got != int64(budget) {
			t.Errorf("initial budget: got %d, want %d", got, budget)
		}

		const newBudget int64 = 55e9 // 55GB
		cfg := env.Editor.Config()
		cfg.Settings["maxFileCacheBytes"] = newBudget
		env.ChangeConfiguration(cfg)
		env.AfterChange()

		// Verify that the budget was updated.
		if got := filecache.SetBudget(-1); got != int64(newBudget) {
			t.Errorf("updated budget: got %d, want %d", got, newBudget)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/fix_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"

	"golang.org/x/tools/gopls/internal/protocol"
)

// A basic test for fillstruct, now that it uses a command and supports resolve edits.
func TestFillStruct(t *testing.T) {
	tc := []struct {
		name         string
		capabilities string
		wantCommand  bool
	}{
		{"default", "{}", false},
		{"no data support", `{"textDocument": {"codeAction": {"dataSupport": false, "resolveSupport": {"properties": ["edit"]}}}}`, true},
		{"no resolve support", `{"textDocument": {"codeAction": {"dataSupport": true, "resolveSupport": {"properties": []}}}}`, true},
		{"data and resolve support", `{"textDocument": {"codeAction": {"dataSupport": true, "resolveSupport": {"properties": ["edit"]}}}}`, false},
	}

	const basic = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
package main

type Info struct {
	WordCounts map[string]int
	Words []string
}

func Foo() {
	_ = Info{}
}
`

	for _, tt := range tc {
		t.Run(tt.name, func(t *testing.T) {
			runner := WithOptions(CapabilitiesJSON([]byte(tt.capabilities)))

			runner.Run(t, basic, func(t *testing.T, env *Env) {
				env.OpenFile("main.go")
				fixes, err := env.Editor.CodeActions(env.Ctx, env.RegexpSearch("main.go", "Info{}"), nil, settings.RefactorRewriteFillStruct)
				if err != nil {
					t.Fatal(err)
				}

				if len(fixes) != 1 {
					t.Fatalf("expected 1 code action, got %v", len(fixes))
				}
				if tt.wantCommand {
					if fixes[0].Command == nil || fixes[0].Data != nil {
						t.Errorf("expected code action to have command not data, got %v", fixes[0])
					}
				} else {
					if fixes[0].Command != nil || fixes[0].Data == nil {
						t.Errorf("expected code action to have command not data, got %v", fixes[0])
					}
				}

				// Apply the code action (handles resolving the code action), and check that the result is correct.
				if err := env.Editor.RefactorRewrite(env.Ctx, env.RegexpSearch("main.go", "Info{}")); err != nil {
					t.Fatal(err)
				}
				want := `package main

type Info struct {
	WordCounts map[string]int
	Words []string
}

func Foo() {
	_ = Info{
		WordCounts: map[string]int{},
		Words:      []string{},
	}
}
`
				if got := env.BufferText("main.go"); got != want {
					t.Fatalf("TestFillStruct failed:\n%s", compare.Text(want, got))
				}
			})
		})
	}
}

func TestFillReturns(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func Foo() error {
	return
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			// The error message here changed in 1.18; "return values" covers both forms.
			Diagnostics(env.AtRegexp("main.go", `return`), WithMessage("return values")),
			ReadDiagnostics("main.go", &d),
		)
		var quickFixes []*protocol.CodeAction
		for _, act := range env.CodeActionForFile("main.go", d.Diagnostics) {
			if act.Kind == protocol.QuickFix {
				act := act // remove in go1.22
				quickFixes = append(quickFixes, &act)
			}
		}
		if len(quickFixes) != 1 {
			t.Fatalf("expected 1 quick fix, got %d:\n%v", len(quickFixes), quickFixes)
		}
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

func TestUnusedParameter_Issue63755(t *testing.T) {
	// This test verifies the fix for #63755, where codeActions panicked on parameters
	// of functions with no function body.

	// We should not detect parameters as unused for external functions.

	const files = `
-- go.mod --
module unused.mod

go 1.18

-- external.go --
package external

func External(z int)

func _() {
	External(1)
}
	`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("external.go")
		_, err := env.Editor.CodeAction(env.Ctx, env.RegexpSearch("external.go", "z"), nil, protocol.CodeActionUnknownTrigger)
		if err != nil {
			t.Fatal(err)
		}
		// yay, no panic
	})
}


================================================
FILE: gopls/internal/test/integration/misc/formatting_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

const unformattedProgram = `
-- main.go --
package main
import "fmt"
func main(  ) {
	fmt.Println("Hello World.")
}
-- main.go.golden --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}
`

func TestFormatting(t *testing.T) {
	Run(t, unformattedProgram, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.FormatBuffer("main.go")
		got := env.BufferText("main.go")
		want := env.ReadWorkspaceFile("main.go.golden")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

// Tests golang/go#36824.
func TestFormattingOneLine36824(t *testing.T) {
	const onelineProgram = `
-- a.go --
package main; func f() {}

-- a.go.formatted --
package main

func f() {}
`
	Run(t, onelineProgram, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.FormatBuffer("a.go")
		got := env.BufferText("a.go")
		want := env.ReadWorkspaceFile("a.go.formatted")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

// Tests golang/go#36824.
func TestFormattingOneLineImports36824(t *testing.T) {
	const onelineProgramA = `
-- a.go --
package x; func f() {fmt.Println()}

-- a.go.imported --
package x

import "fmt"

func f() { fmt.Println() }
`
	Run(t, onelineProgramA, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.OrganizeImports("a.go")
		got := env.BufferText("a.go")
		want := env.ReadWorkspaceFile("a.go.imported")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

func TestFormattingOneLineRmImports36824(t *testing.T) {
	const onelineProgramB = `
-- a.go --
package x; import "os"; func f() {}

-- a.go.imported --
package x

func f() {}
`
	Run(t, onelineProgramB, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.OrganizeImports("a.go")
		got := env.BufferText("a.go")
		want := env.ReadWorkspaceFile("a.go.imported")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

const disorganizedProgram = `
-- main.go --
package main

import (
	"fmt"
	"errors"
)
func main(  ) {
	fmt.Println(errors.New("bad"))
}
-- main.go.organized --
package main

import (
	"errors"
	"fmt"
)
func main(  ) {
	fmt.Println(errors.New("bad"))
}
-- main.go.formatted --
package main

import (
	"errors"
	"fmt"
)

func main() {
	fmt.Println(errors.New("bad"))
}
`

func TestOrganizeImports(t *testing.T) {
	Run(t, disorganizedProgram, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OrganizeImports("main.go")
		got := env.BufferText("main.go")
		want := env.ReadWorkspaceFile("main.go.organized")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

func TestFormattingOnSave(t *testing.T) {
	Run(t, disorganizedProgram, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.SaveBuffer("main.go")
		got := env.BufferText("main.go")
		want := env.ReadWorkspaceFile("main.go.formatted")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

// Tests various possibilities for comments in files with CRLF line endings.
// Import organization in these files has historically been a source of bugs.
func TestCRLFLineEndings(t *testing.T) {
	for _, tt := range []struct {
		issue, input, want string
	}{
		{
			issue: "41057",
			want: `package main

/*
Hi description
*/
func Hi() {
}
`,
		},
		{
			issue: "42646",
			want: `package main

import (
	"fmt"
)

/*
func upload(c echo.Context) error {
	if err := r.ParseForm(); err != nil {
		fmt.Fprintf(w, "ParseForm() err: %v", err)
		return
	}
	fmt.Fprintf(w, "POST request successful")
	path_ver := r.FormValue("path_ver")
	ukclin_ver := r.FormValue("ukclin_ver")

	fmt.Fprintf(w, "Name = %s\n", path_ver)
	fmt.Fprintf(w, "Address = %s\n", ukclin_ver)
}
*/

func main() {
	const server_port = 8080
	fmt.Printf("port: %d\n", server_port)
}
`,
		},
		{
			issue: "42923",
			want: `package main

// Line 1.
// aa
type Tree struct {
	arr []string
}
`,
		},
		{
			issue: "47200",
			input: `package main

import "fmt"

func main() {
	math.Sqrt(9)
	fmt.Println("hello")
}
`,
			want: `package main

import (
	"fmt"
	"math"
)

func main() {
	math.Sqrt(9)
	fmt.Println("hello")
}
`,
		},
	} {
		t.Run(tt.issue, func(t *testing.T) {
			Run(t, "-- main.go --", func(t *testing.T, env *Env) {
				input := tt.input
				if input == "" {
					input = tt.want
				}
				crlf := strings.ReplaceAll(input, "\n", "\r\n")
				env.CreateBuffer("main.go", crlf)
				env.Await(env.DoneWithOpen())
				env.OrganizeImports("main.go")
				got := env.BufferText("main.go")
				got = strings.ReplaceAll(got, "\r\n", "\n") // convert everything to LF for simplicity
				if tt.want != got {
					t.Errorf("unexpected content after save:\n%s", compare.Text(tt.want, got))
				}
			})
		})
	}
}

func TestGofumptFormatting(t *testing.T) {
	// Exercise some gofumpt formatting rules:
	//  - No empty lines following an assignment operator
	//  - Octal integer literals should use the 0o prefix on modules using Go
	//    1.13 and later. Requires LangVersion to be correctly resolved.
	//  - std imports must be in a separate group at the top. Requires ModulePath
	//    to be correctly resolved.
	const input = `
-- go.mod --
module foo

go 1.17
-- foo.go --
package foo

import (
	"foo/bar"
	"fmt"
)

const perm = 0755

func foo() {
	foo :=
		"bar"
	fmt.Println(foo, bar.Bar)
}
-- foo.go.formatted --
package foo

import (
	"fmt"

	"foo/bar"
)

const perm = 0o755

func foo() {
	foo := "bar"
	fmt.Println(foo, bar.Bar)
}
-- bar/bar.go --
package bar

const Bar = 42
`

	WithOptions(
		Settings{
			"gofumpt": true,
		},
	).Run(t, input, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		env.FormatBuffer("foo.go")
		got := env.BufferText("foo.go")
		want := env.ReadWorkspaceFile("foo.go.formatted")
		if got != want {
			t.Errorf("unexpected formatting result:\n%s", compare.Text(want, got))
		}
	})
}

func TestGofumpt_Issue61692(t *testing.T) {
	const input = `
-- go.mod --
module foo

go 1.21rc3
-- foo.go --
package foo

func _() {
	foo :=
		"bar"
}
`

	WithOptions(
		Settings{
			"gofumpt": true,
		},
	).Run(t, input, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		env.FormatBuffer("foo.go") // golang/go#61692: must not panic
	})
}


================================================
FILE: gopls/internal/test/integration/misc/generate_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// TODO(rfindley): figure out why go generate fails on android builders.

//go:build !android

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestGenerateProgress(t *testing.T) {
	const generatedWorkspace = `
-- go.mod --
module fake.test

go 1.14
-- generate.go --
// +build ignore

package main

import (
	"os"
)

func main() {
	os.WriteFile("generated.go", []byte("package " + os.Args[1] + "\n\nconst Answer = 21"), 0644)
}

-- lib1/lib.go --
package lib1

//` + `go:generate go run ../generate.go lib1

-- lib2/lib.go --
package lib2

//` + `go:generate go run ../generate.go lib2

-- main.go --
package main

import (
	"fake.test/lib1"
	"fake.test/lib2"
)

func main() {
	println(lib1.Answer + lib2.Answer)
}
`

	Run(t, generatedWorkspace, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", "lib1.(Answer)")),
		)
		env.RunGenerate("./lib1")
		env.RunGenerate("./lib2")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

func TestGenerateUseNetwork(t *testing.T) {
	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.21
-- example.com@v1.2.3/main.go --
package main

func main() {
	println("hello world")
}
`
	const generatedWorkspace = `
-- go.mod --
module fake.test

go 1.21
-- main.go --

package main

//go:` + /* hide this string from the go command */ `generate go run example.com@latest

`
	WithOptions(ProxyFiles(proxy)).
		Run(t, generatedWorkspace, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
			)
			env.RunGenerate("./")
		})
}

func TestEditingGeneratedFileWarning(t *testing.T) {
	const src = `
-- go.mod --
module example.com
go 1.21

-- a/a.go --
// Code generated by me. DO NOT EDIT.

package a

var x = 1
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		collectMessages := env.Awaiter.ListenToShownMessages()
		env.RegexpReplace("a/a.go", "var", "const")
		env.Await(env.DoneWithChange())
		messages := collectMessages()

		const want = "Warning: editing a.go, a generated file."
		if len(messages) != 1 || messages[0].Message != want {
			for _, message := range messages {
				t.Errorf("got message %q", message.Message)
			}
			t.Errorf("no %q warning", want)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/highlight_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"sort"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestWorkspacePackageHighlight(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
	var A string = "A"
	x := "x-" + A
	println(A, x)
}`

	Run(t, mod, func(t *testing.T, env *Env) {
		const file = "main.go"
		env.OpenFile(file)
		loc := env.FirstDefinition(env.RegexpSearch(file, `var (A) string`))

		checkHighlights(env, loc, 3)
	})
}

func TestStdPackageHighlight_Issue43511(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Printf()
}`

	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		defLoc := env.FirstDefinition(env.RegexpSearch("main.go", `fmt\.(Printf)`))
		file := env.Sandbox.Workdir.URIToPath(defLoc.URI)
		env.OpenFile(file)
		loc := env.RegexpSearch(file, `func Printf\((format) string`)

		checkHighlights(env, loc, 2)
	})
}

func TestThirdPartyPackageHighlight_Issue43511(t *testing.T) {
	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/global/global.go --
package global

const A = 1

func foo() {
	_ = A
}

func bar() int {
	return A + A
}
-- example.com@v1.2.3/local/local.go --
package local

func foo() int {
	const b = 2

	return b * b * (b+1) + b
}`

	const mod = `
-- go.mod --
module mod.com

go 1.12

require example.com v1.2.3
-- main.go --
package main

import (
	_ "example.com/global"
	_ "example.com/local"
)

func main() {}`

	WithOptions(
		ProxyFiles(proxy),
		WriteGoSum("."),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")

		defLoc := env.FirstDefinition(env.RegexpSearch("main.go", `"example.com/global"`))
		file := env.Sandbox.Workdir.URIToPath(defLoc.URI)
		env.OpenFile(file)
		loc := env.RegexpSearch(file, `const (A)`)
		checkHighlights(env, loc, 4)

		defLoc = env.FirstDefinition(env.RegexpSearch("main.go", `"example.com/local"`))
		file = env.Sandbox.Workdir.URIToPath(defLoc.URI)
		env.OpenFile(file)
		loc = env.RegexpSearch(file, `const (b)`)
		checkHighlights(env, loc, 5)
	})
}

func checkHighlights(env *Env, loc protocol.Location, highlightCount int) {
	t := env.TB
	t.Helper()

	highlights := env.DocumentHighlight(loc)
	if len(highlights) != highlightCount {
		t.Fatalf("expected %v highlight(s), got %v", highlightCount, len(highlights))
	}

	references := env.References(loc)
	if len(highlights) != len(references) {
		t.Fatalf("number of highlights and references is expected to be equal: %v != %v", len(highlights), len(references))
	}

	sort.Slice(highlights, func(i, j int) bool {
		return protocol.CompareRange(highlights[i].Range, highlights[j].Range) < 0
	})
	sort.Slice(references, func(i, j int) bool {
		return protocol.CompareRange(references[i].Range, references[j].Range) < 0
	})
	for i := range highlights {
		if highlights[i].Range != references[i].Range {
			t.Errorf("highlight and reference ranges are expected to be equal: %v != %v", highlights[i].Range, references[i].Range)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/misc/hover_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"regexp"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

func TestHoverUnexported(t *testing.T) {
	const proxy = `
-- golang.org/x/structs@v1.0.0/go.mod --
module golang.org/x/structs

go 1.21

-- golang.org/x/structs@v1.0.0/types.go --
package structs

type Mixed struct {
	// Exported comment
	Exported   int
	unexported string
}

func printMixed(m Mixed) {
	println(m)
}
`
	const mod = `
-- go.mod --
module mod.com

go 1.21

require golang.org/x/structs v1.0.0
-- main.go --
package main

import "golang.org/x/structs"

func main() {
	var m structs.Mixed
	_ = m.Exported
}
`

	// TODO: use a nested workspace folder here.
	WithOptions(
		ProxyFiles(proxy),
		WriteGoSum("."),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		mixedLoc := env.RegexpSearch("main.go", "Mixed")
		got, _ := env.Hover(mixedLoc)
		if !strings.Contains(got.Value, "unexported") {
			t.Errorf("Workspace hover: missing expected field 'unexported'. Got:\n%q", got.Value)
		}

		cacheLoc := env.FirstDefinition(mixedLoc)
		cacheFile := env.Sandbox.Workdir.URIToPath(cacheLoc.URI)
		env.OpenFile(cacheFile)
		argLoc := env.RegexpSearch(cacheFile, "printMixed.*(Mixed)")
		got, _ = env.Hover(argLoc)
		if !strings.Contains(got.Value, "unexported") {
			t.Errorf("Non-workspace hover: missing expected field 'unexported'. Got:\n%q", got.Value)
		}

		exportedFieldLoc := env.RegexpSearch("main.go", "Exported")
		got, _ = env.Hover(exportedFieldLoc)
		if !strings.Contains(got.Value, "comment") {
			t.Errorf("Workspace hover: missing comment for field 'Exported'. Got:\n%q", got.Value)
		}
	})
}

func TestHoverIntLiteral(t *testing.T) {
	const source = `
-- main.go --
package main

var (
	bigBin = 0b1001001
)

var hex = 0xe34e

func main() {
}
`
	Run(t, source, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		hexExpected := "58190"
		got, _ := env.Hover(env.RegexpSearch("main.go", "0xe"))
		if got != nil && !strings.Contains(got.Value, hexExpected) {
			t.Errorf("Hover: missing expected field '%s'. Got:\n%q", hexExpected, got.Value)
		}

		binExpected := "73"
		got, _ = env.Hover(env.RegexpSearch("main.go", "0b1"))
		if got != nil && !strings.Contains(got.Value, binExpected) {
			t.Errorf("Hover: missing expected field '%s'. Got:\n%q", binExpected, got.Value)
		}
	})
}

// Tests that hovering does not trigger the panic in golang/go#48249.
func TestPanicInHoverBrokenCode(t *testing.T) {
	// Note: this test can not be expressed as a marker test, as it must use
	// content without a trailing newline.
	const source = `
-- main.go --
package main

type Example struct`
	Run(t, source, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Editor.Hover(env.Ctx, env.RegexpSearch("main.go", "Example"))
	})
}

func TestHoverRune_48492(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.EditBuffer("main.go", fake.NewEdit(0, 0, 1, 0, "package main\nfunc main() {\nconst x = `\nfoo\n`\n}"))
		env.Editor.Hover(env.Ctx, env.RegexpSearch("main.go", "foo"))
	})
}

func TestHoverImport(t *testing.T) {
	const packageDoc1 = "Package lib1 hover documentation"
	const packageDoc2 = "Package lib2 hover documentation"
	tests := []struct {
		hoverPackage string
		want         string
		wantError    bool
	}{
		{
			"mod.com/lib1",
			packageDoc1,
			false,
		},
		{
			"mod.com/lib2",
			packageDoc2,
			false,
		},
		{
			"mod.com/lib3",
			"",
			false,
		},
		{
			"mod.com/lib4",
			"",
			true,
		},
	}
	source := fmt.Sprintf(`
-- go.mod --
module mod.com

go 1.12
-- lib1/a.go --
// %s
package lib1

const C = 1

-- lib1/b.go --
package lib1

const D = 1

-- lib2/a.go --
// %s
package lib2

const E = 1

-- lib3/a.go --
package lib3

const F = 1

-- main.go --
package main

import (
	"mod.com/lib1"
	"mod.com/lib2"
	"mod.com/lib3"
	"mod.com/lib4"
)

func main() {
	println("Hello")
}
	`, packageDoc1, packageDoc2)
	Run(t, source, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		for _, test := range tests {
			got, _, err := env.Editor.Hover(env.Ctx, env.RegexpSearch("main.go", test.hoverPackage))
			if test.wantError {
				if err == nil {
					t.Errorf("Hover(%q) succeeded unexpectedly", test.hoverPackage)
				}
			} else if !strings.Contains(got.Value, test.want) {
				t.Errorf("Hover(%q): got:\n%q\nwant:\n%q", test.hoverPackage, got.Value, test.want)
			}
		}
	})
}

func TestHoverPackageIdent(t *testing.T) {
	const packageDoc1 = "Package lib1 hover documentation"
	const packageDoc2 = "Package lib2 hover documentation"
	tests := []struct {
		hoverIdent string
		want       string
		wantError  bool
	}{
		{
			"lib1",
			packageDoc1,
			false,
		},
		{
			"lib2",
			packageDoc2,
			false,
		},
		{
			"lib3",
			"",
			false,
		},
		{
			"lib4",
			"",
			true,
		},
	}
	source := fmt.Sprintf(`
-- go.mod --
module mod.com

go 1.12
-- lib1/a.go --
// %s
package lib1

const C = 1

-- lib1/b.go --
package lib1

const D = 1

-- lib2/a.go --
// %s
package lib2

const E = 1

-- lib3/a.go --
package lib3

const F = 1

-- main.go --
package main

import (
	"mod.com/lib1"
	"mod.com/lib2"
	"mod.com/lib3"
	"mod.com/lib4"
)

func main() {
	println(lib1.C)
	println(lib2.E)
	println(lib3.F)
	println(lib4.Z)
}
	`, packageDoc1, packageDoc2)
	Run(t, source, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		for _, test := range tests {
			got, _, err := env.Editor.Hover(env.Ctx, env.RegexpSearch("main.go", "("+test.hoverIdent+")\\."))
			if test.wantError {
				if err == nil {
					t.Errorf("Hover(%q) succeeded unexpectedly", test.hoverIdent)
				}
			} else if !strings.Contains(got.Value, test.want) {
				t.Errorf("Hover(%q): got:\n%q\nwant:\n%q", test.hoverIdent, got.Value, test.want)
			}
		}
	})
}

// for x/tools/gopls: unhandled named anchor on the hover #57048
func TestHoverTags(t *testing.T) {
	const source = `
-- go.mod --
module mod.com

go 1.19

-- lib/a.go --

// variety of execution modes.
//
// # Test package setup
//
// The regression test package uses a couple of uncommon patterns to reduce
package lib

-- a.go --
	package main
	import "mod.com/lib"

	const A = 1

}
`
	Run(t, source, func(t *testing.T, env *Env) {
		t.Run("tags", func(t *testing.T) {
			env.OpenFile("a.go")
			z := env.RegexpSearch("a.go", "lib")
			t.Logf("%#v", z)
			got, _ := env.Hover(env.RegexpSearch("a.go", "lib"))
			if strings.Contains(got.Value, "{#hdr-") {
				t.Errorf("Hover: got {#hdr- tag:\n%q", got)
			}
		})
	})
}

// This is a regression test for Go issue #57625.
func TestHoverModMissingModuleStmt(t *testing.T) {
	const source = `
-- go.mod --
go 1.16
`
	Run(t, source, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.Hover(env.RegexpSearch("go.mod", "go")) // no panic
	})
}

func TestHoverCompletionMarkdown(t *testing.T) {
	const source = `
-- go.mod --
module mod.com
go 1.19
-- main.go --
package main
// Just says [hello].
//
// [hello]: https://en.wikipedia.org/wiki/Hello
func Hello() string {
	Hello() //Here
    return "hello"
}
`
	Run(t, source, func(t *testing.T, env *Env) {
		// Hover, Completion, and SignatureHelp should all produce markdown
		// check that the markdown for SignatureHelp and Completion are
		// the same, and contained in that for Hover (up to trailing \n)
		env.OpenFile("main.go")
		loc := env.RegexpSearch("main.go", "func ()Hello")
		hover, _ := env.Hover(loc)
		hoverContent := hover.Value

		loc = env.RegexpSearch("main.go", `Hello()\(\) \/\/Here`) // Hello_() //Here
		completions := env.Completion(loc)
		signatures := env.SignatureHelp(loc)

		if len(completions.Items) != 1 {
			t.Errorf("got %d completions, expected 1", len(completions.Items))
		}
		if len(signatures.Signatures) != 1 {
			t.Errorf("got %d signatures, expected 1", len(signatures.Signatures))
		}
		item := completions.Items[0].Documentation.Value
		var itemContent string
		if x, ok := item.(protocol.MarkupContent); !ok || x.Kind != protocol.Markdown {
			t.Fatalf("%#v is not markdown", item)
		} else {
			itemContent = strings.Trim(x.Value, "\n")
		}
		sig := signatures.Signatures[0].Documentation.Value
		var sigContent string
		if x, ok := sig.(protocol.MarkupContent); !ok || x.Kind != protocol.Markdown {
			t.Fatalf("%#v is not markdown", item)
		} else {
			sigContent = x.Value
		}
		if itemContent != sigContent {
			t.Errorf("item:%q not sig:%q", itemContent, sigContent)
		}
		if !strings.Contains(hoverContent, itemContent) {
			t.Errorf("hover:%q does not contain sig;%q", hoverContent, sigContent)
		}
	})
}

// Test that the generated markdown contains links for Go references.
// https://github.com/golang/go/issues/58352
func TestHoverLinks(t *testing.T) {
	const input = `
-- go.mod --
go 1.19
module mod.com
-- main.go --
package main
// [fmt]
var A int
// [fmt.Println]
var B int
// [golang.org/x/tools/go/packages.Package.String]
var C int
`
	var tests = []struct {
		pat string
		ans string
	}{
		{"A", "fmt"},
		{"B", "fmt#Println"},
		{"C", "golang.org/x/tools/go/packages#Package.String"},
	}
	for _, test := range tests {
		Run(t, input, func(t *testing.T, env *Env) {
			env.OpenFile("main.go")
			loc := env.RegexpSearch("main.go", test.pat)
			hover, _ := env.Hover(loc)
			hoverContent := hover.Value
			want := fmt.Sprintf("%s/%s", "https://pkg.go.dev", test.ans)
			if !strings.Contains(hoverContent, want) {
				t.Errorf("hover:%q does not contain link %q", hoverContent, want)
			}
		})
	}
}

const linknameHover = `
-- go.mod --
module mod.com

-- upper/upper.go --
package upper

import (
	_ "unsafe"
	_ "mod.com/lower"
)

//go:linkname foo mod.com/lower.bar
func foo() string

-- lower/lower.go --
package lower

// bar does foo.
func bar() string {
	return "foo by bar"
}`

func TestHoverLinknameDirective(t *testing.T) {
	Run(t, linknameHover, func(t *testing.T, env *Env) {
		// Jump from directives 2nd arg.
		env.OpenFile("upper/upper.go")
		from := env.RegexpSearch("upper/upper.go", `lower.bar`)

		hover, _ := env.Hover(from)
		content := hover.Value

		expect := "bar does foo"
		if !strings.Contains(content, expect) {
			t.Errorf("hover: %q does not contain: %q", content, expect)
		}
	})
}

func TestHoverGoWork_Issue60821(t *testing.T) {
	const files = `
-- go.work --
go 1.19

use (
	moda
	modb
)
-- moda/go.mod --

`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")
		// Neither of the requests below should crash gopls.
		_, _, _ = env.Editor.Hover(env.Ctx, env.RegexpSearch("go.work", "moda"))
		_, _, _ = env.Editor.Hover(env.Ctx, env.RegexpSearch("go.work", "modb"))
	})
}

const embedHover = `
-- go.mod --
module mod.com
go 1.19
-- main.go --
package main

import "embed"

//go:embed *.txt
var foo embed.FS

func main() {
}
-- foo.txt --
FOO
-- bar.txt --
BAR
-- baz.txt --
BAZ
-- other.sql --
SKIPPED
-- dir.txt/skip.txt --
SKIPPED
`

func TestHoverEmbedDirective(t *testing.T) {
	Run(t, embedHover, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		from := env.RegexpSearch("main.go", `\*.txt`)

		got, _ := env.Hover(from)
		if got == nil {
			t.Fatalf("hover over //go:embed arg not found")
		}
		content := got.Value

		wants := []string{"foo.txt", "bar.txt", "baz.txt"}
		for _, want := range wants {
			if !strings.Contains(content, want) {
				t.Errorf("hover: %q does not contain: %q", content, want)
			}
		}

		// A directory should never be matched, even if it happens to have a matching name.
		// Content in subdirectories should not match on only one asterisk.
		skips := []string{"other.sql", "dir.txt", "skip.txt"}
		for _, skip := range skips {
			if strings.Contains(content, skip) {
				t.Errorf("hover: %q should not contain: %q", content, skip)
			}
		}
	})
}

func TestHoverBrokenImport_Issue60592(t *testing.T) {
	const files = `
-- go.mod --
module testdata
go 1.18

-- p.go --
package main

import foo "a"

func _() {
	foo.Print()
}

`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		// This request should not crash gopls.
		_, _, _ = env.Editor.Hover(env.Ctx, env.RegexpSearch("p.go", "foo[.]"))
	})
}

func TestHoverInternalLinks(t *testing.T) {
	const src = `
-- main.go --
package main

import "errors"

func main() {
	errors.New("oops")
}
`
	for _, test := range []struct {
		linksInHover any    // JSON configuration value
		wantRE       string // pattern to match the Hover Markdown output
	}{
		{
			true, // default: use options.LinkTarget domain
			regexp.QuoteMeta("[`errors.New` on pkg.go.dev](https://pkg.go.dev/errors#New)"),
		},
		{
			"gopls", // use gopls' internal viewer
			"\\[`errors.New` in gopls doc viewer\\]\\(http://127.0.0.1:[0-9]+/gopls/[^/]+/pkg/errors\\?view=[0-9]+#New\\)",
		},
	} {
		WithOptions(
			Settings{"linksInHover": test.linksInHover},
		).Run(t, src, func(t *testing.T, env *Env) {
			env.OpenFile("main.go")
			got, _ := env.Hover(env.RegexpSearch("main.go", "New"))
			if m, err := regexp.MatchString(test.wantRE, got.Value); err != nil {
				t.Fatalf("bad regexp in test: %v", err)
			} else if !m {
				t.Fatalf("hover output does not match %q; got:\n\n%s", test.wantRE, got.Value)
			}
		})
	}
}

func TestHoverInternalLinksIssue68116(t *testing.T) {
	// Links for the internal viewer should not include a module version suffix:
	// the package path and the view are an unambiguous key; see #68116.

	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12

-- example.com@v1.2.3/a/a.go --
package a

// F is a function.
func F()
`

	const mod = `
-- go.mod --
module main

go 1.12

require example.com v1.2.3

-- main.go --
package main

import "example.com/a"

func main() {
	a.F()
}
`
	WithOptions(
		ProxyFiles(proxy),
		Settings{"linksInHover": "gopls"},
		WriteGoSum("."),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		got, _ := env.Hover(env.RegexpSearch("main.go", "F"))
		const wantRE = "\\[`a.F` in gopls doc viewer\\]\\(http://127.0.0.1:[0-9]+/gopls/[^/]+/pkg/example.com/a\\?view=[0-9]+#F\\)" // no version
		if m, err := regexp.MatchString(wantRE, got.Value); err != nil {
			t.Fatalf("bad regexp in test: %v", err)
		} else if !m {
			t.Fatalf("hover output does not match %q; got:\n\n%s", wantRE, got.Value)
		}
	})
}

func TestHoverBuiltinFile(t *testing.T) {
	// This test verifies that hovering in the builtin file provides the same
	// hover content as hovering over a use of a builtin.

	const src = `
-- p.go --
package p

func _() {
	const (
		_ = iota
		_ = true
	)
	var (
		_ any
		err error = e{} // avoid nil deref warning
	)
	_ = err.Error
	println("Hello")
	_ = min(1, 2)
}

// e implements Error, for use above.
type e struct{}
func (e) Error() string
`

	// Test hovering over various builtins with different kinds of declarations.
	tests := []string{
		"iota",
		"true",
		"any",
		"error",
		"Error",
		"println",
		"min",
	}

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.AfterChange(NoDiagnostics()) // avoid accidental compiler errors

		for _, builtin := range tests {
			useLocation := env.RegexpSearch("p.go", builtin)
			calleeHover, _ := env.Hover(useLocation)
			declLocation := env.FirstDefinition(useLocation)
			env.OpenFile(env.Sandbox.Workdir.URIToPath(declLocation.URI))
			declHover, _ := env.Hover(declLocation)
			if diff := cmp.Diff(calleeHover, declHover); diff != "" {
				t.Errorf("Hover mismatch (-callee hover +decl hover):\n%s", diff)
			}
		}
	})
}

func TestHoverStdlibWithAvailableVersion(t *testing.T) {
	const src = `
-- stdlib.go --
package stdlib

import "fmt"
import "context"
import "crypto"
import "regexp"
import "go/doc/comment"

type testRegexp = *regexp.Regexp

func _() {
	var ctx context.Context
	ctx = context.Background()
	if ctx.Err(); e == context.Canceled {
		fmt.Println("Canceled")
		fmt.Printf("%v", crypto.SHA512_224)
	}
	_ := fmt.Appendf(make([]byte, 100), "world, %d", 23)

	var re = regexp.MustCompile("\n{2,}")
	copy := re.Copy()
	var testRE testRegexp
	testRE.Longest()

	var pr comment.Printer
	pr.HeadingID = func(*comment.Heading) string { return "" }
}
`

	testcases := []struct {
		symbolRE      string // regexp matching symbol to hover over
		shouldContain bool
		targetString  string
	}{
		{"Println", false, "go1.0"},   // package-level func
		{"Appendf", true, "go1.19"},   // package-level func
		{"Background", true, "go1.7"}, // package-level func
		{"Canceled", true, "go1.7"},   // package-level var
		{"Context", true, "go1.7"},    // package-level type
		{"SHA512_224", true, "go1.5"}, // package-level const
		{"Copy", true, "go1.6"},       // method
		{"Longest", true, "go1.1"},    // method with alias receiver
		{"HeadingID", true, "go1.19"}, // field
	}

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("stdlib.go")
		for _, tc := range testcases {
			content, _ := env.Hover(env.RegexpSearch("stdlib.go", tc.symbolRE))
			if tc.shouldContain && !strings.Contains(content.Value, tc.targetString) {
				t.Errorf("Hover(%q) should contain string %s", tc.symbolRE, tc.targetString)
			}
			if !tc.shouldContain && strings.Contains(content.Value, tc.targetString) {
				t.Errorf("Hover(%q) should not contain string %s", tc.symbolRE, tc.targetString)
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/import_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestAddImport(t *testing.T) {
	const before = `package main

import "fmt"

func main() {
	fmt.Println("hello world")
}
`

	const want = `package main

import (
	"bytes"
	"fmt"
)

func main() {
	fmt.Println("hello world")
}
`

	Run(t, "", func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", before)
		cmd := command.NewAddImportCommand("Add Import", command.AddImportArgs{
			URI:        env.Sandbox.Workdir.URI("main.go"),
			ImportPath: "bytes",
		})
		env.ExecuteCommand(&protocol.ExecuteCommandParams{
			Command:   command.AddImport.String(),
			Arguments: cmd.Arguments,
		}, nil)
		got := env.BufferText("main.go")
		if got != want {
			t.Fatalf("gopls.add_import failed\n%s", compare.Text(want, got))
		}
	})
}

func TestListImports(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo.go --
package foo
const C = 1
-- import_strings_test.go --
package foo
import (
	x "strings"
	"testing"
)

func TestFoo(t *testing.T) {}
-- import_testing_test.go --
package foo

import "testing"

func TestFoo2(t *testing.T) {}
`
	tests := []struct {
		filename string
		want     command.ListImportsResult
	}{
		{
			filename: "import_strings_test.go",
			want: command.ListImportsResult{
				Imports: []command.FileImport{
					{Name: "x", Path: "strings"},
					{Path: "testing"},
				},
				PackageImports: []command.PackageImport{
					{Path: "strings"},
					{Path: "testing"},
				},
			},
		},
		{
			filename: "import_testing_test.go",
			want: command.ListImportsResult{
				Imports: []command.FileImport{
					{Path: "testing"},
				},
				PackageImports: []command.PackageImport{
					{Path: "strings"},
					{Path: "testing"},
				},
			},
		},
	}

	Run(t, files, func(t *testing.T, env *Env) {
		for _, tt := range tests {
			cmd := command.NewListImportsCommand("List Imports", command.URIArg{
				URI: env.Sandbox.Workdir.URI(tt.filename),
			})
			var result command.ListImportsResult
			env.ExecuteCommand(&protocol.ExecuteCommandParams{
				Command:   command.ListImports.String(),
				Arguments: cmd.Arguments,
			}, &result)
			if diff := cmp.Diff(tt.want, result); diff != "" {
				t.Errorf("unexpected list imports result for %q (-want +got):\n%s", tt.filename, diff)
			}
		}

	})
}


================================================
FILE: gopls/internal/test/integration/misc/imports_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/settings"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/modindex"

	"golang.org/x/tools/gopls/internal/protocol"
)

// Tests golang/go#38815.
func TestIssue38815(t *testing.T) {
	const needs = `
-- go.mod --
module foo

go 1.12
-- a.go --
package main
func f() {}
`
	const ntest = `package main
func TestZ(t *testing.T) {
	f()
}
`
	const want = `package main

import "testing"

func TestZ(t *testing.T) {
	f()
}
`

	// it was returning
	// "package main\nimport \"testing\"\npackage main..."
	Run(t, needs, func(t *testing.T, env *Env) {
		env.CreateBuffer("a_test.go", ntest)
		env.SaveBuffer("a_test.go")
		got := env.BufferText("a_test.go")
		if want != got {
			t.Errorf("got\n%q, wanted\n%q", got, want)
		}
	})
}

func TestIssue59124(t *testing.T) {
	const stuff = `
-- go.mod --
module foo
go 1.19
-- a.go --
//line foo.y:102
package main

import "fmt"

//this comment is necessary for failure
func _() {
	fmt.Println("hello")
}
`
	Run(t, stuff, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		was := env.BufferText("a.go")
		env.AfterChange(NoDiagnostics())
		env.OrganizeImports("a.go")
		is := env.BufferText("a.go")
		if diff := compare.Text(was, is); diff != "" {
			t.Errorf("unexpected diff after organizeImports:\n%s", diff)
		}
	})
}

func TestIssue66407(t *testing.T) {
	const files = `
-- go.mod --
module foo
go 1.21
-- a.go --
package foo

func f(x float64) float64 {
	return x +  rand.Float64()
}
-- b.go --
package foo

func _() {
	_ = rand.Int63()
}
`
	WithOptions(Modes(Default)).
		Run(t, files, func(t *testing.T, env *Env) {
			env.OpenFile("a.go")
			was := env.BufferText("a.go")
			env.OrganizeImports("a.go")
			is := env.BufferText("a.go")
			// expect complaint that module is before 1.22
			env.AfterChange(Diagnostics(ForFile("a.go")))
			diff := compare.Text(was, is)
			// check that it found the 'right' rand
			if !strings.Contains(diff, `import "math/rand/v2"`) {
				t.Errorf("expected rand/v2, got %q", diff)
			}
			env.OpenFile("b.go")
			was = env.BufferText("b.go")
			env.OrganizeImports("b.go")
			// a.go still has its module problem but b.go is fine
			env.AfterChange(Diagnostics(ForFile("a.go")),
				NoDiagnostics(ForFile("b.go")))
			is = env.BufferText("b.go")
			diff = compare.Text(was, is)
			if !strings.Contains(diff, `import "math/rand"`) {
				t.Errorf("expected math/rand, got %q", diff)
			}
		})
}

func TestVim1(t *testing.T) {
	const vim1 = `package main

import "fmt"

var foo = 1
var bar = 2

func main() {
	fmt.Printf("This is a test %v\n", foo)
	fmt.Printf("This is another test %v\n", foo)
	fmt.Printf("This is also a test %v\n", foo)
}
`

	// The file remains unchanged, but if there any quick fixes
	// are returned, they confuse vim (according to CL 233117).
	// Therefore check for no QuickFix CodeActions.
	Run(t, "", func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", vim1)
		env.OrganizeImports("main.go")

		// Assert no quick fixes.
		for _, act := range env.CodeActionForFile("main.go", nil) {
			if act.Kind == protocol.QuickFix {
				t.Errorf("unexpected quick fix action: %#v", act)
			}
		}
		if t.Failed() {
			got := env.BufferText("main.go")
			if got == vim1 {
				t.Errorf("no changes")
			} else {
				t.Errorf("got\n%q", got)
				t.Errorf("was\n%q", vim1)
			}
		}
	})
}

func TestVim2(t *testing.T) {
	const vim2 = `package main

import (
	"fmt"

	"example.com/blah"

	"rubbish.com/useless"
)

func main() {
	fmt.Println(blah.Name, useless.Name)
}
`

	Run(t, "", func(t *testing.T, env *Env) {
		env.CreateBuffer("main.go", vim2)
		env.OrganizeImports("main.go")

		// Assert no quick fixes.
		for _, act := range env.CodeActionForFile("main.go", nil) {
			if act.Kind == protocol.QuickFix {
				t.Errorf("unexpected quick-fix action: %#v", act)
			}
		}
	})
}

const exampleProxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/x/x.go --
package x

const X = 1
-- example.com@v1.2.3/y/y.go --
package y

const Y = 2
`

func TestGOMODCACHE(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12

require example.com v1.2.3
-- main.go --
package main

import "example.com/x"

var _, _ = x.X, y.Y
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)

	opts := []RunOption{
		EnvVars{"GOMODCACHE": modcache},
		ProxyFiles(exampleProxy),
		WriteGoSum("."),
	}

	// Force go list to populate GOMODCACHE
	// so OrganizeImports can later rely on it.
	t.Run("setup", func(t *testing.T) {
		WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {})
	})

	WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {
		// Expect y is undefined.
		env.OpenFile("main.go")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", `y.Y`),
				WithMessage("undefined")),
		)

		// Apply suggested fix via OrganizeImports.
		env.SaveBuffer("main.go") // => OrganizeImports
		if true {
			// according to https://github.com/golang/go/issues/77894
			// this test is flaky. Print some possibly helpful diagnostic
			// information.
			ix, err := modindex.Read(modcache)
			if err != nil {
				t.Logf("could not read modcache index: %v", err)
			} else if len(ix.Entries) != 2 {
				t.Logf("%d modcache entries", len(ix.Entries))
				if len(ix.Entries) == 0 {
					fis, err := os.ReadDir(modcache)
					if err != nil {
						t.Logf("could not read modcache dir: %v", err)
					}
					t.Logf("%d modcache files", len(fis))
				}
			}
		}
		env.AfterChange(NoDiagnostics(ForFile("main.go")))

		// Verify that y.Y is defined within the module cache.
		loc := env.FirstDefinition(env.RegexpSearch("main.go", `y.(Y)`))
		path := env.Sandbox.Workdir.URIToPath(loc.URI)
		if !strings.HasPrefix(path, filepath.ToSlash(modcache)) {
			t.Errorf("found module dependency outside of GOMODCACHE: got %v, wanted subdir of %v", path, filepath.ToSlash(modcache))
		}
	})
}

// make sure it gets the v2
/* marker test?

Add proxy data with the special proxy/ prefix (see gopls/internal/test/marker/testdata/quickfix/unusedrequire.txt).
Invoke the organizeImports codeaction directly (see gopls/internal/test/marker/testdata/codeaction/imports.txt, but use the edit=golden named argument instead of result= to minimize the size of the golden output.
*/
func Test58382(t *testing.T) {
	files := `-- main.go --
package main
import "fmt"
func main() {
	fmt.Println(xurls.Relaxed().FindAllString())
}
-- go.mod --
module demo
go 1.20
`
	cache := `-- mvdan.cc/xurls@v2.5.0/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
--  github.com/mvdan/xurls/v2@v1.1.0/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)
	mx := fake.UnpackTxt(cache)

	for k, v := range mx {
		fname := filepath.Join(modcache, k)
		dir := filepath.Dir(fname)
		os.MkdirAll(dir, 0777) // ignore error
		if err := os.WriteFile(fname, v, 0644); err != nil {
			t.Fatal(err)
		}
		if true {
			// for diagnosing flakiness
			t.Logf("wrote %s:%d", fname, len(v))
		}
	}
	WithOptions(
		EnvVars{"GOMODCACHE": modcache},
		WriteGoSum("."),
		Settings{"importsSource": settings.ImportsSourceGopls},
		NoLogsOnError(),
	).Run(t, files, func(t *testing.T, env *Env) {

		env.OpenFile("main.go")
		env.SaveBuffer("main.go")
		out := env.BufferText("main.go")
		if !strings.Contains(out, "xurls/v2") {
			t.Errorf("did not get v2 in %q", out)
			// golang/go#77552 finds this test flaky, so print out more
			ix, err := modindex.Read(modcache)
			if err != nil {
				t.Fatal(err)
			}
			t.Logf("%d entries", len(ix.Entries))
			for i, e := range ix.Entries {
				t.Logf("%d: %s, %s, %d", i, e.ImportPath, e.Dir, len(e.Names))
			}
		}
	})
}

// get the version requested in the go.mod file, not /v2
func Test61208(t *testing.T) {
	files := `-- main.go --
package main
import "fmt"
func main() {
	fmt.Println(xurls.Relaxed().FindAllString())
}
-- go.mod --
module demo
go 1.20
require github.com/mvdan/xurls v1.1.0
`
	cache := `-- mvdan.cc/xurls/v2@v2.5.0/a/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
--  github.com/mvdan/xurls@v1.1.0/a/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)
	mx := fake.UnpackTxt(cache)
	for k, v := range mx {
		fname := filepath.Join(modcache, k)
		dir := filepath.Dir(fname)
		os.MkdirAll(dir, 0777) // ignore error
		if err := os.WriteFile(fname, v, 0644); err != nil {
			t.Fatal(err)
		}
	}
	WithOptions(
		EnvVars{"GOMODCACHE": modcache},
		WriteGoSum("."),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.SaveBuffer("main.go")
		out := env.BufferText("main.go")
		if !strings.Contains(out, "github.com/mvdan/xurls") {
			t.Errorf("did not get github.com/mvdan/xurls in %q", out)
		}
	})
}

// get the version already used in the module
func Test60663(t *testing.T) {
	files := `-- main.go --
package main
import "fmt"
func main() {
	fmt.Println(xurls.Relaxed().FindAllString())
}
-- go.mod --
module demo
go 1.20
-- a.go --
package main
import "github.com/mvdan/xurls"
var _ = xurls.Relaxed()
`
	cache := `-- mvdan.cc/xurls/v2@v2.5.0/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
--  github.com/mvdan/xurls@v1.1.0/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)
	mx := fake.UnpackTxt(cache)
	for k, v := range mx {
		fname := filepath.Join(modcache, k)
		dir := filepath.Dir(fname)
		os.MkdirAll(dir, 0777) // ignore error
		if err := os.WriteFile(fname, v, 0644); err != nil {
			t.Fatal(err)
		}
	}
	WithOptions(
		EnvVars{"GOMODCACHE": modcache},
		WriteGoSum("."),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.SaveBuffer("main.go")
		out := env.BufferText("main.go")
		if !strings.Contains(out, "github.com/mvdan/xurls") {
			t.Errorf("did not get github.com/mvdan/xurls in %q", out)
		}
	})
}

// use the import from a different package in the same module
func Test44510(t *testing.T) {
	const files = `-- go.mod --
module test
go 1.19
-- foo/foo.go --
package main
import strs "strings"
var _ = strs.Count
-- bar/bar.go --
package main
var _ = strs.Builder
`
	WithOptions(
		WriteGoSum("."),
	).Run(t, files, func(T *testing.T, env *Env) {
		env.OpenFile("bar/bar.go")
		env.SaveBuffer("bar/bar.go")
		buf := env.BufferText("bar/bar.go")
		if !strings.Contains(buf, "strs") {
			t.Error(buf)
		}
	})
}

func TestIssue67156(t *testing.T) {
	const files = `
-- go.mod --
module mod.com/a

go 1.20

require example.com v1.2.3

-- main.go --
package main

import "example.com/x"

var _, _ = x.X, y.Y
`
	modcache := t.TempDir()
	base := filepath.Base(modcache)
	defer CleanModCache(t, modcache)

	// Construct a very unclean module cache whose length exceeds the length of
	// the clean directory path, to reproduce the crash in golang/go#67156
	const sep = string(filepath.Separator)
	modcache += strings.Repeat(sep+".."+sep+base, 10)

	opts := []RunOption{
		EnvVars{"GOMODCACHE": modcache},
		ProxyFiles(exampleProxy),
		WriteGoSum("."),
	}

	t.Run("setup", func(t *testing.T) {
		// Force go list to populate GOMODCACHE.
		WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {})

		// Update module index.
		if ix, err := modindex.Update(modcache); err != nil {
			t.Fatalf("failed to obtain updated module index: %v", err)
		} else if len(ix.Entries) != 2 {
			t.Fatalf("got %v, want 2 entries", ix)
		}
	})

	WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(Diagnostics(env.AtRegexp("main.go", `y.Y`)))
		env.SaveBuffer("main.go") // => OrganizeImports
		env.AfterChange(NoDiagnostics(ForFile("main.go")))
	})
}

// Tests golang/go#40685.
func TestAcceptImportsQuickFixTestVariant(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

import (
	"fmt"
)

func _() {
	fmt.Println("")
	os.Stat("")
}
-- a/a_test.go --
package a

import (
	"os"
	"testing"
)

func TestA(t *testing.T) {
	os.Stat("")
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "os.Stat")),
			ReadDiagnostics("a/a.go", &d),
		)
		env.ApplyQuickFixes("a/a.go", d.Diagnostics)
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
	})
}

// Test of golang/go#70755
func TestQuickFixIssue70755(t *testing.T) {
	const files = `
-- go.mod --
module mod.com
go 1.19.0 // with go 1.23.0 this fails on some builders
-- bar/bar.go --
package notbar
type NotBar struct {}
-- baz/baz.go --
package baz
type Baz struct {}
-- foo/foo.go --
package foo
type Foo struct {
	bar notbar.NotBar
	baz baz.Baz
}`
	WithOptions(
		Settings{"importsSource": settings.ImportsSourceGopls}).
		Run(t, files, func(t *testing.T, env *Env) {
			env.OpenFile("foo/foo.go")
			var d protocol.PublishDiagnosticsParams
			env.AfterChange(ReadDiagnostics("foo/foo.go", &d))
			env.ApplyQuickFixes("foo/foo.go", d.Diagnostics)
			// at this point 'import notbar "mod.com/bar"' has been added
			// but it's still missing the import of "mod.com/baz"
			y := env.BufferText("foo/foo.go")
			if !strings.Contains(y, `notbar "mod.com/bar"`) {
				t.Error("quick fix did not find notbar")
			}
			env.SaveBuffer("foo/foo.go")
			env.AfterChange(NoDiagnostics(ForFile("foo/foo.go")))
		})
}

// Test for golang/go#52784
func TestGoWorkImports(t *testing.T) {
	const pkg = `
-- go.work --
go 1.19

use (
        ./caller
        ./mod
)
-- caller/go.mod --
module caller.com

go 1.18

require mod.com v0.0.0

replace mod.com => ../mod
-- caller/caller.go --
package main

func main() {
        a.Test()
}
-- mod/go.mod --
module mod.com

go 1.18
-- mod/a/a.go --
package a

func Test() {
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("caller/caller.go")
		env.AfterChange(Diagnostics(env.AtRegexp("caller/caller.go", "a.Test")))

		// Saving caller.go should trigger goimports, which should find a.Test in
		// the mod.com module, thanks to the go.work file.
		env.SaveBuffer("caller/caller.go")
		env.AfterChange(NoDiagnostics(ForFile("caller/caller.go")))
	})
}

// prefer the undeprecated alternative 70736
func TestDeprecated70736(t *testing.T) {
	t.Logf("GOOS %s, GARCH %s version %s", runtime.GOOS, runtime.GOARCH, runtime.Version())
	files := `-- main.go --
package main
func main() {
	var v = xurls.Relaxed().FindAllString()
	var w = xurls.A
}
-- go.mod --
module demo
go 1.20
`
	cache := `-- mvdan.cc/xurls/v2@v2.5.0/xurls.go --
package xurls
// Deprecated:
func Relaxed() *regexp.Regexp {
return nil
}
var A int
--  github.com/mvdan/xurls@v1.1.0/xurls.go --
package xurls
func Relaxed() *regexp.Regexp {
return nil
}
var A int
`
	modcache := t.TempDir()
	defer CleanModCache(t, modcache)
	mx := fake.UnpackTxt(cache)
	for k, v := range mx {
		fname := filepath.Join(modcache, k)
		dir := filepath.Dir(fname)
		os.MkdirAll(dir, 0777) // ignore error
		if err := os.WriteFile(fname, v, 0644); err != nil {
			t.Fatal(err)
		}
	}
	WithOptions(
		EnvVars{"GOMODCACHE": modcache},
		WriteGoSum("."),
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.SaveBuffer("main.go")
		out := env.BufferText("main.go")
		if strings.Contains(out, "xurls/v2") {
			t.Errorf("chose deprecated v2 in %q", out)
		}
	})
}

// Find the non-test package asked for in a test
func TestTestImports(t *testing.T) {
	const pkg = `
-- go.work --
go 1.19

use (
        ./caller
        ./mod
		./xxx
)
-- caller/go.mod --
module caller.com

go 1.18

require mod.com v0.0.0
require xxx.com v0.0.0

replace mod.com => ../mod
replace xxx.com => ../xxx
-- caller/caller_test.go --
package main

var _ = a.Test
-- xxx/go.mod --
module xxx.com

go 1.18
-- xxx/a/a_test.go --
package a

func Test() {
}
-- mod/go.mod --
module mod.com

go 1.18
-- mod/a/a.go --
package a

func Test() {
}
`
	WithOptions(Modes(Default)).Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("caller/caller_test.go")
		env.AfterChange(Diagnostics(env.AtRegexp("caller/caller_test.go", "a.Test")))

		// Saving caller_test.go should trigger goimports, which should find a.Test in
		// the mod.com module, thanks to the go.work file.
		env.SaveBuffer("caller/caller_test.go")
		env.AfterChange(NoDiagnostics(ForFile("caller/caller_test.go")))
		buf := env.BufferText("caller/caller_test.go")
		if !strings.Contains(buf, "mod.com/a") {
			t.Errorf("got %q, expected a mod.com/a", buf)
		}
	})
}

// this test replaces 'package bar' with 'package foo'
// saves the file, and then looks for the import in the main package.s
func Test67973(t *testing.T) {
	const files = `-- go.mod --
module hello
go 1.19
-- hello.go --
package main
var _ = foo.Bar
-- internal/foo/foo.go --
package bar
func Bar() {}
`
	WithOptions(
		Settings{"importsSource": settings.ImportsSourceGopls},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("hello.go")
		env.AfterChange(env.DoneWithOpen())
		env.SaveBuffer("hello.go")
		env.OpenFile("internal/foo/foo.go")
		env.RegexpReplace("internal/foo/foo.go", "bar", "foo")
		env.SaveBuffer("internal/foo/foo.go")
		env.SaveBuffer("hello.go")
		buf := env.BufferText("hello.go")
		if !strings.Contains(buf, "internal/foo") {
			t.Errorf(`expected import "hello/internal/foo" but got %q`, buf)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/link_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"path/filepath"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestHoverAndDocumentLink(t *testing.T) {
	const program = `
-- go.mod --
module mod.test

go 1.12

require import.test v1.2.3

require replace.test v1.2.3
replace replace.test => replace.test v1.2.4

require replace.fixed.test v1.2.3
replace replace.fixed.test v1.2.3 => replace.fixed.test v1.2.4

require replace.another.test v1.2.3
replace replace.another.test => another.test v1.2.3


replace example.com/non-exist => ./
replace example.com/non-exist1 => ../work/

-- main.go --
package main

import "import.test/pkg"
import "replace.test/replace"
import "replace.fixed.test/fixed"
import "replace.another.test/another"

func main() {
	// Issue 43990: this is not a link that most users can open from an LSP
	// client: mongodb://not.a.link.com
	println(pkg.Hello)
	println(replace.Hello)
	println(fixed.Hello)
	println(another.Hello)
}`

	const proxy = `
-- import.test@v1.2.3/go.mod --
module import.test

go 1.12
-- import.test@v1.2.3/pkg/const.go --
// package documentation
package pkg


-- replace.test@v1.2.4/go.mod --
module replace.test

go 1.12
-- replace.test@v1.2.4/replace/const.go --
package replace

const Hello = "Hello"

-- replace.fixed.test@v1.2.4/go.mod --
module replace.fixed.test

go 1.12
-- replace.fixed.test@v1.2.4/fixed/const.go --
package fixed

const Hello = "Hello"

-- another.test@v1.2.3/go.mod --
module another.test

go 1.12
-- another.test@v1.2.3/another/const.go --
package another

const Hello = "Hello"
`
	WithOptions(
		ProxyFiles(proxy),
		WriteGoSum("."),
	).Run(t, program, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OpenFile("go.mod")

		const (
			modImportLink        = "https://pkg.go.dev/mod/import.test@v1.2.3"
			modReplaceLink       = "https://pkg.go.dev/mod/replace.test@v1.2.4"
			modReplaceFixedeLink = "https://pkg.go.dev/mod/replace.fixed.test@v1.2.4"
			modAnotherLink       = "https://pkg.go.dev/mod/another.test@v1.2.3"

			pkgImportLink       = "https://pkg.go.dev/import.test@v1.2.3/pkg"
			pkgReplaceLink      = "https://pkg.go.dev/replace.test@v1.2.4/replace"
			pkgReplaceFixedLink = "https://pkg.go.dev/replace.fixed.test@v1.2.4/fixed"
			pkgAnotherLink      = "https://pkg.go.dev/another.test@v1.2.3/another"
			pkgDoc              = "package documentation"
		)

		// First, check that we get the expected links via hover and documentLink.
		content, _ := env.Hover(env.RegexpSearch("main.go", "()pkg.Hello"))
		if content == nil || !strings.Contains(content.Value, pkgImportLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgImportLink)
		}
		content, _ = env.Hover(env.RegexpSearch("main.go", "()replace.Hello"))
		if content == nil || !strings.Contains(content.Value, pkgReplaceLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgReplaceLink)
		}
		content, _ = env.Hover(env.RegexpSearch("main.go", "()fixed.Hello"))
		if content == nil || !strings.Contains(content.Value, pkgReplaceFixedLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgReplaceFixedLink)
		}
		content, _ = env.Hover(env.RegexpSearch("main.go", "()another.Hello"))
		if content == nil || !strings.Contains(content.Value, pkgAnotherLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgAnotherLink)
		}

		content, _ = env.Hover(env.RegexpSearch("go.mod", "()import.test"))
		if content == nil || !strings.Contains(content.Value, pkgImportLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgImportLink)
		}
		content, _ = env.Hover(env.RegexpSearch("go.mod", "()replace.test"))
		if content == nil || !strings.Contains(content.Value, pkgReplaceLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgReplaceLink)
		}
		content, _ = env.Hover(env.RegexpSearch("go.mod", "()replace.fixed.test"))
		if content == nil || !strings.Contains(content.Value, pkgReplaceFixedLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgReplaceFixedLink)
		}
		content, _ = env.Hover(env.RegexpSearch("go.mod", "()replace.another.test"))
		if content == nil || !strings.Contains(content.Value, pkgAnotherLink) {
			t.Errorf("hover: got %v in main.go, want contains %q", content, pkgAnotherLink)
		}

		getLinks := func(links []protocol.DocumentLink) []string {
			var got []string
			for i := range links {
				got = append(got, *links[i].Target)
			}
			return got
		}
		links := env.DocumentLink("main.go")
		got, want := getLinks(links), []string{
			pkgImportLink,
			pkgReplaceLink,
			pkgReplaceFixedLink,
			pkgAnotherLink,
		}
		if !slices.Equal(got, want) {
			t.Errorf("documentLink: got links %v for main.go, want links %v", got, want)
		}

		links = env.DocumentLink("go.mod")
		localReplacePath := filepath.Join(env.Sandbox.Workdir.RootURI().Path(), "go.mod")
		got, want = getLinks(links), []string{
			localReplacePath, localReplacePath,
			modImportLink,
			modReplaceLink,
			modReplaceFixedeLink,
			modAnotherLink,
		}
		if !slices.Equal(got, want) {
			t.Errorf("documentLink: got links %v for go.mod, want links %v", got, want)
		}

		// Then change the environment to make these links private.
		cfg := env.Editor.Config()
		cfg.Env = map[string]string{"GOPRIVATE": "import.test"}
		env.ChangeConfiguration(cfg)

		// Finally, verify that the links are gone.
		content, _ = env.Hover(env.RegexpSearch("main.go", "()pkg.Hello"))
		if content == nil || strings.Contains(content.Value, pkgImportLink) {
			t.Errorf("hover: got %v in main.go, want non-empty hover without %q", content, pkgImportLink)
		}
		content, _ = env.Hover(env.RegexpSearch("go.mod", "()import.test"))
		if content == nil || strings.Contains(content.Value, modImportLink) {
			t.Errorf("hover: got %v in go.mod, want contains %q", content, modImportLink)
		}

		links = env.DocumentLink("main.go")
		got, want = getLinks(links), []string{
			pkgReplaceLink,
			pkgReplaceFixedLink,
			pkgAnotherLink,
		}
		if !slices.Equal(got, want) {
			t.Errorf("documentLink: got links %v for main.go, want links %v", got, want)
		}

		links = env.DocumentLink("go.mod")
		got, want = getLinks(links), []string{
			localReplacePath, localReplacePath,
			modReplaceLink,
			modReplaceFixedeLink,
			modAnotherLink,
		}
		if !slices.Equal(got, want) {
			t.Errorf("documentLink: got links %v for go.mod, want links %v", got, want)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/misc_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"os"
	"strings"
	"testing"

	"golang.org/x/telemetry/counter/countertest"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	tmp, err := os.MkdirTemp("", "gopls-misc-test-counters")
	if err != nil {
		panic(err)
	}
	countertest.Open(tmp)
	code := Main(m)
	os.RemoveAll(tmp) // ignore error (cleanup fails on Windows; golang/go#68243)
	os.Exit(code)
}

// TestDocumentURIFix ensures that a DocumentURI supplied by the
// client is subject to the "fixing" operation documented at
// [protocol.DocumentURI.UnmarshalText]. The details of the fixing are
// tested in the protocol package; here we aim to test only that it
// occurs at all.
func TestDocumentURIFix(t *testing.T) {
	const mod = `
-- go.mod --
module testdata
go 1.18

-- a.go --
package a

const K = 1
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		loc := env.RegexpSearch("a.go", "K")
		path := strings.TrimPrefix(string(loc.URI), "file://") // (absolute)

		check := func() {
			t.Helper()
			t.Logf("URI = %s", loc.URI)
			content, _ := env.Hover(loc) // must succeed
			if content == nil || !strings.Contains(content.Value, "const K") {
				t.Errorf("wrong content: %#v", content)
			}
		}

		// Regular URI (e.g. file://$TMPDIR/TestDocumentURIFix/default/work/a.go)
		check()

		// URL-encoded path (e.g. contains %2F instead of last /)
		loc.URI = protocol.DocumentURI("file://" + strings.Replace(path, "/a.go", "%2Fa.go", 1))
		check()

		// We intentionally do not test further cases (e.g.
		// file:// without a third slash) as it would quickly
		// get bogged down in irrelevant details of the
		// fake editor's own handling of URIs.
	})
}


================================================
FILE: gopls/internal/test/integration/misc/modify_tags_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/compare"
	"golang.org/x/tools/gopls/internal/test/integration"
)

func TestModifyTags(t *testing.T) {
	const files = `
-- go.mod --
module example.com

go 1.20

-- a.go --
package a

type A struct {
	B string
	C int
	D bool
	E string
}

-- b.go --
package b

type B struct {
	B string ` + "`json:\"b,omitempty\"`" + `
	C int    ` + "`json:\"c,omitempty\"`" + `
	D bool   ` + "`json:\"d,omitempty\"`" + `
	E string ` + "`json:\"e,omitempty\"`" + `
}

-- c.go --
package c

type C struct {
	B string
	C int
	D bool ` + "`json:\"d,omitempty\"`" + `
	E string
}
`

	const wantAddTagsEntireStruct = `package a

type A struct {
	B string ` + "`json:\"b,omitempty\"`" + `
	C int    ` + "`json:\"c,omitempty\"`" + `
	D bool   ` + "`json:\"d,omitempty\"`" + `
	E string ` + "`json:\"e,omitempty\"`" + `
}
`

	const wantRemoveTags = `package b

type B struct {
	B string
	C int
	D bool   ` + "`json:\"d,omitempty\"`" + `
	E string ` + "`json:\"e,omitempty\"`" + `
}
`

	const wantAddTagsSingleLine = `package a

type A struct {
	B string
	C int
	D bool ` + "`json:\"d,omitempty\"`" + `
	E string
}
`

	const wantRemoveOptions = `package c

type C struct {
	B string
	C int
	D bool ` + "`json:\"d\"`" + `
	E string
}
`

	tests := []struct {
		file string
		args command.ModifyTagsArgs
		want string
	}{
		{file: "a.go", args: command.ModifyTagsArgs{
			Range: protocol.Range{
				Start: protocol.Position{Line: 2, Character: 0},
				End:   protocol.Position{Line: 8, Character: 0},
			},
			Add:        "json",
			AddOptions: "json=omitempty",
		}, want: wantAddTagsEntireStruct},
		{file: "b.go", args: command.ModifyTagsArgs{
			Range: protocol.Range{
				Start: protocol.Position{Line: 3, Character: 2},
				End:   protocol.Position{Line: 4, Character: 6},
			},
			Remove: "json",
		}, want: wantRemoveTags},
		{file: "a.go", args: command.ModifyTagsArgs{
			Range: protocol.Range{
				Start: protocol.Position{Line: 5, Character: 0},
				End:   protocol.Position{Line: 5, Character: 7},
			},
			Add:        "json",
			AddOptions: "json=omitempty",
		}, want: wantAddTagsSingleLine},
		{file: "c.go", args: command.ModifyTagsArgs{
			Range: protocol.Range{
				Start: protocol.Position{Line: 3, Character: 0},
				End:   protocol.Position{Line: 7, Character: 0},
			},
			RemoveOptions: "json=omitempty",
		}, want: wantRemoveOptions},
	}

	for _, test := range tests {
		integration.Run(t, files, func(t *testing.T, env *integration.Env) {
			uri := env.Sandbox.Workdir.URI(test.file)
			args, err := command.MarshalArgs(
				command.ModifyTagsArgs{
					URI:           uri,
					Range:         test.args.Range,
					Add:           test.args.Add,
					AddOptions:    test.args.AddOptions,
					Remove:        test.args.Remove,
					RemoveOptions: test.args.RemoveOptions,
				},
			)
			if err != nil {
				t.Fatal(err)
			}
			var res any
			env.ExecuteCommand(&protocol.ExecuteCommandParams{
				Command:   command.ModifyTags.String(),
				Arguments: args,
			}, &res)
			// Wait until we finish writing to the file.
			env.AfterChange()
			if got := env.BufferText(test.file); got != test.want {
				t.Errorf("modify_tags returned unexpected diff (-want +got):\n%s", compare.Text(test.want, got))
			}
		})
	}
}


================================================
FILE: gopls/internal/test/integration/misc/multiple_adhoc_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestMultipleAdHocPackages(t *testing.T) {
	Run(t, `
-- a/a.go --
package main

import "fmt"

func main() {
	fmt.Println("")
}
-- a/b.go --
package main

import "fmt"

func main() () {
	fmt.Println("")
}
`, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		if list := env.Completion(env.RegexpSearch("a/a.go", "()Println")); list == nil || len(list.Items) == 0 {
			t.Fatal("expected completions, got none")
		}
		env.OpenFile("a/b.go")
		if list := env.Completion(env.RegexpSearch("a/b.go", "()Println")); list == nil || len(list.Items) == 0 {
			t.Fatal("expected completions, got none")
		}
		if list := env.Completion(env.RegexpSearch("a/a.go", "()Println")); list == nil || len(list.Items) == 0 {
			t.Fatal("expected completions, got none")
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/package_symbols_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration"
)

func TestPackageSymbols(t *testing.T) {
	const files = `
-- go.mod --
module example.com

go 1.20

-- a.go --
package a

var A = "var"
type S struct{}

func (s *S) M1() {}
-- b.go --
package a

var b = 1

func (s *S) M2() {}

func (s *S) M3() {}

func F() {}
-- unloaded.go --
//go:build unloaded

package a

var Unloaded int
`
	integration.Run(t, files, func(t *testing.T, env *integration.Env) {
		aURI := env.Sandbox.Workdir.URI("a.go")
		bURI := env.Sandbox.Workdir.URI("b.go")
		args, err := command.MarshalArgs(command.PackageSymbolsArgs{
			URI: aURI,
		})
		if err != nil {
			t.Fatal(err)
		}

		var res command.PackageSymbolsResult
		env.ExecuteCommand(&protocol.ExecuteCommandParams{
			Command:   command.PackageSymbols.String(),
			Arguments: args,
		}, &res)

		want := command.PackageSymbolsResult{
			PackageName: "a",
			Files:       []protocol.DocumentURI{aURI, bURI},
			Symbols: []command.PackageSymbol{
				{Name: "A", Kind: protocol.Variable, File: 0},
				{Name: "F", Kind: protocol.Function, File: 1},
				{Name: "S", Kind: protocol.Struct, File: 0, Children: []command.PackageSymbol{
					{Name: "M1", Kind: protocol.Method, File: 0},
					{Name: "M2", Kind: protocol.Method, File: 1},
					{Name: "M3", Kind: protocol.Method, File: 1},
				}},
				{Name: "b", Kind: protocol.Variable, File: 1},
			},
		}
		ignore := cmpopts.IgnoreFields(command.PackageSymbol{}, "Range", "SelectionRange", "Detail")
		if diff := cmp.Diff(want, res, ignore); diff != "" {
			t.Errorf("package_symbols returned unexpected diff (-want +got):\n%s", diff)
		}

		for file, want := range map[string]command.PackageSymbolsResult{
			"go.mod": {},
			"unloaded.go": {
				PackageName: "a",
				Files:       []protocol.DocumentURI{env.Sandbox.Workdir.URI("unloaded.go")},
				Symbols: []command.PackageSymbol{
					{Name: "Unloaded", Kind: protocol.Variable, File: 0},
				},
			},
		} {
			uri := env.Sandbox.Workdir.URI(file)
			args, err := command.MarshalArgs(command.PackageSymbolsArgs{
				URI: uri,
			})
			if err != nil {
				t.Fatal(err)
			}
			var res command.PackageSymbolsResult
			env.ExecuteCommand(&protocol.ExecuteCommandParams{
				Command:   command.PackageSymbols.String(),
				Arguments: args,
			}, &res)

			if diff := cmp.Diff(want, res, ignore); diff != "" {
				t.Errorf("package_symbols returned unexpected diff (-want +got):\n%s", diff)
			}
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/prompt_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/telemetry/counter"
	"golang.org/x/telemetry/counter/countertest"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/server"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test prompt file in old and new formats are handled as expected.
func TestTelemetryPrompt_PromptFile(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {}
`

	defaultTelemetryStartTime := "1714521600" // 2024-05-01
	defaultToken := "7"
	samplesPerMille := "500"

	testCases := []struct {
		name, in, want string
		wantPrompt     bool
	}{
		{
			name:       "empty",
			in:         "",
			want:       "failed 1 1714521600 7",
			wantPrompt: true,
		},
		{
			name:       "v0.15-format/invalid",
			in:         "pending",
			want:       "failed 1 1714521600 7",
			wantPrompt: true,
		},
		{
			name:       "v0.15-format/pPending",
			in:         "pending 1",
			want:       "failed 2 1714521600 7",
			wantPrompt: true,
		},
		{
			name:       "v0.15-format/pPending",
			in:         "failed 1",
			want:       "failed 2 1714521600 7",
			wantPrompt: true,
		},
		{
			name: "v0.15-format/pYes",
			in:   "yes 1",
			want: "yes 1", // untouched since short-circuited
		},
		{
			name: "v0.16-format/pNotReady",
			in:   "- 0 1714521600 1000",
			want: "- 0 1714521600 1000",
		},
		{
			name:       "v0.16-format/pPending",
			in:         "pending 1 1714521600 1",
			want:       "failed 2 1714521600 1",
			wantPrompt: true,
		},
		{
			name:       "v0.16-format/pFailed",
			in:         "failed 2 1714521600 1",
			want:       "failed 3 1714521600 1",
			wantPrompt: true,
		},
		{
			name:       "v0.16-format/invalid",
			in:         "xxx 0 12345 678",
			want:       "failed 1 1714521600 7",
			wantPrompt: true,
		},
		{
			name: "v0.16-format/extra",
			in:   "- 0 1714521600 1000 7777 xxx",
			want: "- 0 1714521600 1000", // drop extra
		},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			modeFile := filepath.Join(t.TempDir(), "mode")
			goplsConfigDir := t.TempDir()
			promptDir := filepath.Join(goplsConfigDir, "prompt")
			promptFile := filepath.Join(promptDir, "telemetry")

			if err := os.MkdirAll(promptDir, 0777); err != nil {
				t.Fatal(err)
			}
			if err := os.WriteFile(promptFile, []byte(tc.in), 0666); err != nil {
				t.Fatal(err)
			}
			WithOptions(
				Modes(Default), // no need to run this in all modes
				EnvVars{
					server.GoplsConfigDirEnvvar:                  goplsConfigDir,
					server.FakeTelemetryModefileEnvvar:           modeFile,
					server.GoTelemetryGoplsClientStartTimeEnvvar: defaultTelemetryStartTime,
					server.GoTelemetryGoplsClientTokenEnvvar:     defaultToken,
					server.FakeSamplesPerMille:                   samplesPerMille,
				},
				Settings{
					"telemetryPrompt": true,
				},
			).Run(t, src, func(t *testing.T, env *Env) {
				expectation := ShownMessageRequest(".*Would you like to enable Go telemetry?")
				if !tc.wantPrompt {
					expectation = Not(expectation)
				}
				env.OnceMet(
					CompletedWork(server.TelemetryPromptWorkTitle, 1, true),
					expectation,
				)
				if got, err := os.ReadFile(promptFile); err != nil || string(got) != tc.want {
					t.Fatalf("(%q) -> (%q, %v), want %q", tc.in, got, err, tc.want)
				}
			})
		})
	}
}

// Test that gopls prompts for telemetry only when it is supposed to.
func TestTelemetryPrompt_Conditions_Mode(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`

	for _, enabled := range []bool{true, false} {
		t.Run(fmt.Sprintf("telemetryPrompt=%v", enabled), func(t *testing.T) {
			for _, initialMode := range []string{"", "local", "off", "on"} {
				t.Run(fmt.Sprintf("initial_mode=%s", initialMode), func(t *testing.T) {
					modeFile := filepath.Join(t.TempDir(), "mode")
					if initialMode != "" {
						if err := os.WriteFile(modeFile, []byte(initialMode), 0666); err != nil {
							t.Fatal(err)
						}
					}
					telemetryStartTime := time.Now().Add(-8 * 24 * time.Hour) // telemetry started a while ago
					WithOptions(
						Modes(Default), // no need to run this in all modes
						EnvVars{
							server.GoplsConfigDirEnvvar:                  t.TempDir(),
							server.FakeTelemetryModefileEnvvar:           modeFile,
							server.GoTelemetryGoplsClientStartTimeEnvvar: strconv.FormatInt(telemetryStartTime.Unix(), 10),
							server.GoTelemetryGoplsClientTokenEnvvar:     "1", // always sample because samplingPerMille >= 1.
						},
						Settings{
							"telemetryPrompt": enabled,
						},
					).Run(t, src, func(t *testing.T, env *Env) {
						wantPrompt := enabled && (initialMode == "" || initialMode == "local")
						expectation := ShownMessageRequest(".*Would you like to enable Go telemetry?")
						if !wantPrompt {
							expectation = Not(expectation)
						}
						env.OnceMet(
							CompletedWork(server.TelemetryPromptWorkTitle, 1, true),
							expectation,
						)
					})
				})
			}
		})
	}
}

// Test that gopls prompts for telemetry only after instrumenting for a while, and
// when the token is within the range for sample.
func TestTelemetryPrompt_Conditions_StartTimeAndSamplingToken(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`
	day := 24 * time.Hour
	samplesPerMille := 50
	for _, token := range []int{1, samplesPerMille, samplesPerMille + 1} {
		wantSampled := token <= samplesPerMille
		t.Run(fmt.Sprintf("to_sample=%t/tokens=%d", wantSampled, token), func(t *testing.T) {
			for _, elapsed := range []time.Duration{8 * day, 1 * day, 0} {
				telemetryStartTimeOrEmpty := ""
				if elapsed > 0 {
					telemetryStartTimeOrEmpty = strconv.FormatInt(time.Now().Add(-elapsed).Unix(), 10)
				}
				t.Run(fmt.Sprintf("elapsed=%s", elapsed), func(t *testing.T) {
					modeFile := filepath.Join(t.TempDir(), "mode")
					WithOptions(
						Modes(Default), // no need to run this in all modes
						EnvVars{
							server.GoplsConfigDirEnvvar:                  t.TempDir(),
							server.FakeTelemetryModefileEnvvar:           modeFile,
							server.GoTelemetryGoplsClientStartTimeEnvvar: telemetryStartTimeOrEmpty,
							server.GoTelemetryGoplsClientTokenEnvvar:     strconv.Itoa(token),
							server.FakeSamplesPerMille:                   strconv.Itoa(samplesPerMille), // want token ∈ [1, 50] is always sampled.
						},
						Settings{
							"telemetryPrompt": true,
						},
					).Run(t, src, func(t *testing.T, env *Env) {
						wantPrompt := wantSampled && elapsed > 7*day
						expectation := ShownMessageRequest(".*Would you like to enable Go telemetry?")
						if !wantPrompt {
							expectation = Not(expectation)
						}
						env.OnceMet(
							CompletedWork(server.TelemetryPromptWorkTitle, 1, true),
							expectation,
						)
					})
				})
			}
		})
	}
}

// Test that responding to the telemetry prompt results in the expected state.
func TestTelemetryPrompt_Response(t *testing.T) {
	if !countertest.SupportedPlatform {
		t.Skip("requires counter support")
	}

	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`

	var (
		acceptanceCounter = "gopls/telemetryprompt/accepted"
		declinedCounter   = "gopls/telemetryprompt/declined"
		attempt1Counter   = "gopls/telemetryprompt/attempts:1"
		allCounters       = []string{acceptanceCounter, declinedCounter, attempt1Counter}
	)

	// To avoid (but not prevent) the flakes encountered in golang/go#68659, we
	// need to perform our first read before starting to increment counters.
	//
	// ReadCounter checks to see if the counter file needs to be rotated before
	// reading. When files are rotated, all previous counts are lost. Calling
	// ReadCounter here reduces the window for a flake due to this rotation (the
	// file was originally was located during countertest.Open in TestMain).
	//
	// golang/go#71590 tracks the larger problems with the countertest library.
	//
	// (The counter name below is arbitrary.)
	_, _ = countertest.ReadCounter(counter.New("issue68659"))

	// We must increment counters in order for the initial reads below to
	// succeed.
	//
	// TODO(rfindley): ReadCounter should simply return 0 for uninitialized
	// counters.
	for _, name := range allCounters {
		counter.New(name).Inc()
	}

	readCounts := func(t *testing.T) map[string]uint64 {
		t.Helper()
		counts := make(map[string]uint64)
		for _, name := range allCounters {
			count, err := countertest.ReadCounter(counter.New(name))
			if err != nil {
				t.Fatalf("ReadCounter(%q) failed: %v", name, err)
			}
			counts[name] = count
		}
		return counts
	}

	tests := []struct {
		name       string // subtest name
		response   string // response to choose for the telemetry dialog
		wantMode   string // resulting telemetry mode
		wantMsg    string // substring contained in the follow-up popup (if empty, no popup is expected)
		wantInc    uint64 // expected 'prompt accepted' counter increment
		wantCounts map[string]uint64
	}{
		{"yes", server.TelemetryYes, "on", "uploading is now enabled", 1, map[string]uint64{
			acceptanceCounter: 1,
			declinedCounter:   0,
			attempt1Counter:   1,
		}},
		{"no", server.TelemetryNo, "", "", 0, map[string]uint64{
			acceptanceCounter: 0,
			declinedCounter:   1,
			attempt1Counter:   1,
		}},
		{"empty", "", "", "", 0, map[string]uint64{
			acceptanceCounter: 0,
			declinedCounter:   0,
			attempt1Counter:   1,
		}},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			initialCounts := readCounts(t)
			modeFile := filepath.Join(t.TempDir(), "mode")
			telemetryStartTime := time.Now().Add(-8 * 24 * time.Hour)
			msgRE := regexp.MustCompile(".*Would you like to enable Go telemetry?")
			respond := func(m *protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error) {
				if msgRE.MatchString(m.Message) {
					for _, item := range m.Actions {
						if item.Title == test.response {
							return &item, nil
						}
					}
					if test.response != "" {
						t.Errorf("action item %q not found", test.response)
					}
				}
				return nil, nil
			}
			WithOptions(
				Modes(Default), // no need to run this in all modes
				EnvVars{
					server.GoplsConfigDirEnvvar:                  t.TempDir(),
					server.FakeTelemetryModefileEnvvar:           modeFile,
					server.GoTelemetryGoplsClientStartTimeEnvvar: strconv.FormatInt(telemetryStartTime.Unix(), 10),
					server.GoTelemetryGoplsClientTokenEnvvar:     "1", // always sample because samplingPerMille >= 1.
				},
				Settings{
					"telemetryPrompt": true,
				},
				MessageResponder(respond),
			).Run(t, src, func(t *testing.T, env *Env) {
				var postConditions []Expectation
				if test.wantMsg != "" {
					postConditions = append(postConditions, ShownMessage(test.wantMsg))
				}
				env.OnceMet(
					CompletedWork(server.TelemetryPromptWorkTitle, 1, true),
					postConditions...,
				)
				gotMode := ""
				if contents, err := os.ReadFile(modeFile); err == nil {
					gotMode = string(contents)
				} else if !os.IsNotExist(err) {
					t.Fatal(err)
				}
				if gotMode != test.wantMode {
					t.Errorf("after prompt, mode=%s, want %s", gotMode, test.wantMode)
				}

				// We increment the acceptance counter when checking the prompt file
				// before prompting, so start a second, transient gopls session and
				// verify that the acceptance counter is incremented.
				env2 := ConnectGoplsEnv(t, env.Ctx, env.Sandbox, env.Editor.Config(), env.Server)
				env2.Await(CompletedWork(server.TelemetryPromptWorkTitle, 1, true))
				if err := env2.Editor.Close(env2.Ctx); err != nil {
					t.Errorf("closing second editor: %v", err)
				}

				gotCounts := readCounts(t)
				for k := range gotCounts {
					gotCounts[k] -= initialCounts[k]
				}
				if diff := cmp.Diff(test.wantCounts, gotCounts); diff != "" {
					t.Errorf("counter mismatch (-want +got):\n%s", diff)
				}
			})
		})
	}
}

// Test that we stop asking about telemetry after the user ignores the question
// 5 times.
func TestTelemetryPrompt_GivingUp(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`

	// For this test, we want to share state across gopls sessions.
	modeFile := filepath.Join(t.TempDir(), "mode")
	telemetryStartTime := time.Now().Add(-30 * 24 * time.Hour)
	configDir := t.TempDir()

	const maxPrompts = 5 // internal prompt limit defined by gopls

	for i := range maxPrompts + 1 {
		WithOptions(
			Modes(Default), // no need to run this in all modes
			EnvVars{
				server.GoplsConfigDirEnvvar:                  configDir,
				server.FakeTelemetryModefileEnvvar:           modeFile,
				server.GoTelemetryGoplsClientStartTimeEnvvar: strconv.FormatInt(telemetryStartTime.Unix(), 10),
				server.GoTelemetryGoplsClientTokenEnvvar:     "1", // always sample because samplingPerMille >= 1.
			},
			Settings{
				"telemetryPrompt": true,
			},
		).Run(t, src, func(t *testing.T, env *Env) {
			wantPrompt := i < maxPrompts
			expectation := ShownMessageRequest(".*Would you like to enable Go telemetry?")
			if !wantPrompt {
				expectation = Not(expectation)
			}
			env.OnceMet(
				CompletedWork(server.TelemetryPromptWorkTitle, 1, true),
				expectation,
			)
		})
	}
}

// Test that gopls prompts for telemetry only when it is supposed to.
func TestTelemetryPrompt_Conditions_Command(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`
	modeFile := filepath.Join(t.TempDir(), "mode")
	telemetryStartTime := time.Now().Add(-8 * 24 * time.Hour)
	WithOptions(
		Modes(Default), // no need to run this in all modes
		EnvVars{
			server.GoplsConfigDirEnvvar:                  t.TempDir(),
			server.FakeTelemetryModefileEnvvar:           modeFile,
			server.GoTelemetryGoplsClientStartTimeEnvvar: fmt.Sprintf("%d", telemetryStartTime.Unix()),
			server.GoTelemetryGoplsClientTokenEnvvar:     "1", // always sample because samplingPerMille >= 1.
		},
		Settings{
			// off because we are testing
			// if we can trigger the prompt with command.
			"telemetryPrompt": false,
		},
	).Run(t, src, func(t *testing.T, env *Env) {
		cmd := command.NewMaybePromptForTelemetryCommand("prompt")
		var err error
		env.ExecuteCommand(&protocol.ExecuteCommandParams{
			Command: cmd.Command,
		}, &err)
		if err != nil {
			t.Fatal(err)
		}
		expectation := ShownMessageRequest(".*Would you like to enable Go telemetry?")
		env.OnceMet(
			CompletedWork(server.TelemetryPromptWorkTitle, 2, true),
			expectation,
		)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/references_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"os"
	"path/filepath"
	"reflect"
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestStdlibReferences(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Print()
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", `fmt.(Print)`))
		env.OpenFile(env.Sandbox.Workdir.URIToPath(loc.URI))
		refs, err := env.Editor.References(env.Ctx, loc)
		if err != nil {
			t.Fatal(err)
		}
		if len(refs) != 2 {
			// TODO(adonovan): make this assertion less maintainer-hostile.
			t.Fatalf("got %v reference(s), want 2", len(refs))
		}
		// The first reference is guaranteed to be the definition.
		if got, want := refs[1].URI, env.Sandbox.Workdir.URI("main.go"); got != want {
			t.Errorf("found reference in %v, wanted %v", got, want)
		}
	})
}

// This is a regression test for golang/go#48400 (a panic).
func TestReferencesOnErrorMethod(t *testing.T) {
	// Ideally this would actually return the correct answer,
	// instead of merely failing gracefully.
	const files = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

type t interface {
	error
}

type s struct{}

func (*s) Error() string {
	return ""
}

func _() {
	var s s
	_ = s.Error()
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", `Error`))
		refs, err := env.Editor.References(env.Ctx, loc)
		if err != nil {
			t.Fatalf("references on (*s).Error failed: %v", err)
		}
		// TODO(adonovan): this test is crying out for marker support in integration tests.
		var buf strings.Builder
		for _, ref := range refs {
			fmt.Fprintf(&buf, "%s %s\n", env.Sandbox.Workdir.URIToPath(ref.URI), ref.Range)
		}
		got := buf.String()
		want := "main.go 8:10-8:15\n" + // (*s).Error decl
			"main.go 14:7-14:12\n" // s.Error() call
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("unexpected references on (*s).Error (-want +got):\n%s", diff)
		}
	})
}

func TestDefsRefsBuiltins(t *testing.T) {
	// TODO(adonovan): add unsafe.{SliceData,String,StringData} in later go versions.
	const files = `
-- go.mod --
module example.com
go 1.16

-- a.go --
package a

import "unsafe"

const _ = iota
var _ error
var _ int
var _ = append()
var _ = unsafe.Pointer(nil)
var _ = unsafe.Add(nil, nil)
var _ = unsafe.Sizeof(0)
var _ = unsafe.Alignof(0)
var _ = unsafe.Slice(nil, 0)
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		for name := range strings.FieldsSeq(
			"iota error int nil append iota Pointer Sizeof Alignof Add Slice") {
			loc := env.RegexpSearch("a.go", `\b`+name+`\b`)

			// definition -> {builtin,unsafe}.go
			def := env.FirstDefinition(loc)
			if (!strings.HasSuffix(string(def.URI), "builtin.go") &&
				!strings.HasSuffix(string(def.URI), "unsafe.go")) ||
				def.Range.Start.Line == 0 {
				t.Errorf("definition(%q) = %v, want {builtin,unsafe}.go",
					name, def)
			}

			// "references to (builtin "Foo"|unsafe.Foo) are not supported"
			_, err := env.Editor.References(env.Ctx, loc)
			gotErr := fmt.Sprint(err)
			if !strings.Contains(gotErr, "references to") ||
				!strings.Contains(gotErr, "not supported") ||
				!strings.Contains(gotErr, name) {
				t.Errorf("references(%q) error: got %q, want %q",
					name, gotErr, "references to ... are not supported")
			}
		}
	})
}

func TestPackageReferences(t *testing.T) {
	tests := []struct {
		packageName  string
		wantRefCount int
		wantFiles    []string
	}{
		{
			"lib1",
			3,
			[]string{
				"main.go",
				"lib1/a.go",
				"lib1/b.go",
			},
		},
		{
			"lib2",
			2,
			[]string{
				"main.go",
				"lib2/a.go",
			},
		},
	}

	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib1/a.go --
package lib1

const A = 1

-- lib1/b.go --
package lib1

const B = 1

-- lib2/a.go --
package lib2

const C = 1

-- main.go --
package main

import (
	"mod.com/lib1"
	"mod.com/lib2"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		for _, test := range tests {
			file := fmt.Sprintf("%s/a.go", test.packageName)
			env.OpenFile(file)
			loc := env.RegexpSearch(file, test.packageName)
			refs := env.References(loc)
			if len(refs) != test.wantRefCount {
				// TODO(adonovan): make this assertion less maintainer-hostile.
				t.Fatalf("got %v reference(s), want %d", len(refs), test.wantRefCount)
			}
			var refURIs []string
			for _, ref := range refs {
				refURIs = append(refURIs, string(ref.URI))
			}
			for _, base := range test.wantFiles {
				hasBase := false
				for _, ref := range refURIs {
					if strings.HasSuffix(ref, base) {
						hasBase = true
						break
					}
				}
				if !hasBase {
					t.Fatalf("got [%v], want reference ends with \"%v\"", strings.Join(refURIs, ","), base)
				}
			}
		}
	})
}

// Test for golang/go#43144.
//
// Verify that we search for references and implementations in intermediate
// test variants.
func TestReferencesInTestVariants(t *testing.T) {
	const files = `
-- go.mod --
module foo.mod

go 1.12
-- foo/foo.go --
package foo

import "foo.mod/bar"

const Foo = 42

type T int
type InterfaceM interface{ M() }
type InterfaceF interface{ F() }

func _() {
	_ = bar.Blah
}

-- foo/foo_test.go --
package foo

type Fer struct{}
func (Fer) F() {}

-- bar/bar.go --
package bar

var Blah = 123

-- bar/bar_test.go --
package bar

type Mer struct{}
func (Mer) M() {}

func TestBar() {
	_ = Blah
}
-- bar/bar_x_test.go --
package bar_test

import (
	"foo.mod/bar"
	"foo.mod/foo"
)

type Mer struct{}
func (Mer) M() {}

func _() {
	_ = bar.Blah
	_ = foo.Foo
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")

		refTests := []struct {
			re       string
			wantRefs []string
		}{
			// Blah is referenced:
			// - inside the foo.mod/bar (ordinary) package
			// - inside the foo.mod/bar [foo.mod/bar.test] test variant package
			// - from the foo.mod/bar_test [foo.mod/bar.test] x_test package
			// - from the foo.mod/foo package
			{"Blah", []string{"bar/bar.go:3", "bar/bar_test.go:7", "bar/bar_x_test.go:12", "foo/foo.go:12"}},

			// Foo is referenced in bar_x_test.go via the intermediate test variant
			// foo.mod/foo [foo.mod/bar.test].
			{"Foo", []string{"bar/bar_x_test.go:13", "foo/foo.go:5"}},
		}

		for _, test := range refTests {
			loc := env.RegexpSearch("foo/foo.go", test.re)
			refs := env.References(loc)

			got := fileLocations(env, refs)
			if diff := cmp.Diff(test.wantRefs, got); diff != "" {
				t.Errorf("References(%q) returned unexpected diff (-want +got):\n%s", test.re, diff)
			}
		}

		implTests := []struct {
			re        string
			wantImpls []string
		}{
			// InterfaceM is implemented both in foo.mod/bar [foo.mod/bar.test] (which
			// doesn't import foo), and in foo.mod/bar_test [foo.mod/bar.test], which
			// imports the test variant of foo.
			{"InterfaceM", []string{"bar/bar_test.go:3", "bar/bar_x_test.go:8"}},

			// A search within the ordinary package to should find implementations
			// (Fer) within the augmented test package.
			{"InterfaceF", []string{"foo/foo_test.go:3"}},
		}

		for _, test := range implTests {
			loc := env.RegexpSearch("foo/foo.go", test.re)
			impls := env.Implementations(loc)

			got := fileLocations(env, impls)
			if diff := cmp.Diff(test.wantImpls, got); diff != "" {
				t.Errorf("Implementations(%q) returned unexpected diff (-want +got):\n%s", test.re, diff)
			}
		}
	})
}

// This is a regression test for Issue #56169, in which interface
// implementations in vendored modules were not found. The actual fix
// was the same as for #55995; see TestVendoringInvalidatesMetadata.
func TestImplementationsInVendor(t *testing.T) {
	const proxy = `
-- other.com/b@v1.0.0/go.mod --
module other.com/b
go 1.14

-- other.com/b@v1.0.0/b.go --
package b
type B int
func (B) F() {}
`
	const src = `
-- go.mod --
module example.com/a
go 1.14
require other.com/b v1.0.0

-- a.go --
package a
import "other.com/b"
type I interface { F() }
var _ b.B

`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
		Modes(Default), // fails in 'experimental' mode
	).Run(t, src, func(t *testing.T, env *Env) {
		// Enable to debug go.sum mismatch, which may appear as
		// "module lookup disabled by GOPROXY=off", confusingly.
		if false {
			env.DumpGoSum(".")
		}

		checkVendor := func(locs []protocol.Location, wantVendor bool) {
			if len(locs) != 1 {
				t.Errorf("got %d locations, want 1", len(locs))
			} else if strings.Contains(string(locs[0].URI), "/vendor/") != wantVendor {
				t.Errorf("got location %s, wantVendor=%t", locs[0], wantVendor)
			}
		}

		env.OpenFile("a.go")
		refLoc := env.RegexpSearch("a.go", "I") // find "I" reference

		// Initially, a.I has one implementation b.B in
		// the module cache, not the vendor tree.
		checkVendor(env.Implementations(refLoc), false)

		// Run 'go mod vendor' outside the editor.
		env.RunGoCommand("mod", "vendor")

		// Synchronize changes to watched files.
		env.Await(env.DoneWithChangeWatchedFiles())

		// Now, b.B is found in the vendor tree.
		checkVendor(env.Implementations(refLoc), true)

		// Delete the vendor tree.
		if err := os.RemoveAll(env.Sandbox.Workdir.AbsPath("vendor")); err != nil {
			t.Fatal(err)
		}
		// Notify the server of the deletion.
		if err := env.Sandbox.Workdir.CheckForFileChanges(env.Ctx); err != nil {
			t.Fatal(err)
		}

		// Synchronize again.
		env.Await(env.DoneWithChangeWatchedFiles())

		// b.B is once again defined in the module cache.
		checkVendor(env.Implementations(refLoc), false)
	})
}

// This test can't be expressed as a marker test because the marker
// test framework opens all files (which is a bit of a hack), creating
// a <command-line-arguments> package for packages that otherwise
// wouldn't be found from the go.work file.
func TestReferencesFromWorkspacePackages59674(t *testing.T) {
	const src = `
-- a/go.mod --
module example.com/a
go 1.12

-- b/go.mod --
module example.com/b
go 1.12

-- c/go.mod --
module example.com/c
go 1.12

-- lib/go.mod --
module example.com/lib
go 1.12

-- go.work --
use ./a
use ./b
// don't use ./c
use ./lib

-- a/a.go --
package a

import "example.com/lib"

var _ = lib.F // query here

-- b/b.go --
package b

import "example.com/lib"

var _ = lib.F // also found by references

-- c/c.go --
package c

import "example.com/lib"

var _ = lib.F // this reference should not be reported

-- lib/lib.go --
package lib

func F() {} // declaration
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		refLoc := env.RegexpSearch("a/a.go", "F")
		got := fileLocations(env, env.References(refLoc))
		want := []string{"a/a.go:5", "b/b.go:5", "lib/lib.go:3"}
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("incorrect References (-want +got):\n%s", diff)
		}
	})
}

// Test an 'implementation' query on a type that implements 'error'.
// (Unfortunately builtin locations cannot be expressed using @loc
// in the marker test framework.)
func TestImplementationsOfError(t *testing.T) {
	const src = `
-- go.mod --
module example.com
go 1.12

-- a.go --
package a

type Error2 interface {
	Error() string
}

type MyError int
func (MyError) Error() string { return "" }

type MyErrorPtr int
func (*MyErrorPtr) Error() string { return "" }
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		for _, test := range []struct {
			re   string
			want []string
		}{
			// error type
			{"Error2", []string{"a.go:10", "a.go:7", "std:builtin/builtin.go"}},
			{"MyError", []string{"a.go:3", "std:builtin/builtin.go"}},
			{"MyErrorPtr", []string{"a.go:3", "std:builtin/builtin.go"}},
			// error.Error method
			{"(Error).. string", []string{"a.go:11", "a.go:8", "std:builtin/builtin.go"}},
			{"MyError. (Error)", []string{"a.go:4", "std:builtin/builtin.go"}},
			{"MyErrorPtr. (Error)", []string{"a.go:4", "std:builtin/builtin.go"}},
		} {
			matchLoc := env.RegexpSearch("a.go", test.re)
			impls := env.Implementations(matchLoc)
			got := fileLocations(env, impls)
			if !reflect.DeepEqual(got, test.want) {
				t.Errorf("Implementations(%q) = %q, want %q",
					test.re, got, test.want)
			}
		}
	})
}

// fileLocations returns a new sorted array of the
// relative file name and line number of each location.
// Duplicates are not removed.
// Standard library filenames are abstracted for robustness.
func fileLocations(env *integration.Env, locs []protocol.Location) []string {
	got := make([]string, 0, len(locs))
	for _, loc := range locs {
		path := env.Sandbox.Workdir.URIToPath(loc.URI) // (slashified)
		if i := strings.LastIndex(path, "/src/"); i >= 0 && filepath.IsAbs(path) {
			// Absolute path with "src" segment: assume it's in GOROOT.
			// Strip directory and don't add line/column since they are fragile.
			path = "std:" + path[i+len("/src/"):]
		} else {
			path = fmt.Sprintf("%s:%d", path, loc.Range.Start.Line+1)
		}
		got = append(got, path)
	}
	sort.Strings(got)
	return got
}


================================================
FILE: gopls/internal/test/integration/misc/rename_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestPrepareRenameMainPackage(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

import (
	"fmt"
)

func main() {
	fmt.Println(1)
}
`
	const wantErr = "can't rename package \"main\""
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		loc := env.RegexpSearch("main.go", `main`)
		params := &protocol.PrepareRenameParams{
			TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		}
		_, err := env.Editor.Server.PrepareRename(env.Ctx, params)
		if err == nil {
			t.Errorf("missing can't rename package main error from PrepareRename")
		}

		if err.Error() != wantErr {
			t.Errorf("got %v, want %v", err.Error(), wantErr)
		}
	})
}

// Test case for golang/go#56227
func TestRenameWithUnsafeSlice(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- p.go --
package p

import "unsafe"

type T struct{}

func (T) M() {}

func _() {
	x := [3]int{1, 2, 3}
	ptr := unsafe.Pointer(&x)
	_ = unsafe.Slice((*int)(ptr), 3)
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.Rename(env.RegexpSearch("p.go", "M"), "N") // must not panic
	})
}

func TestPrepareRenameWithNoPackageDeclaration(t *testing.T) {
	const files = `
go 1.14
-- lib/a.go --
import "fmt"

const A = 1

func bar() {
	fmt.Println("Bar")
}

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		err := env.Editor.Rename(env.Ctx, env.RegexpSearch("lib/a.go", "fmt"), "fmt1")
		if got, want := fmt.Sprint(err), "no identifier found"; got != want {
			t.Errorf("Rename: got error %v, want %v", got, want)
		}
	})
}

func TestPrepareRenameFailWithUnknownModule(t *testing.T) {
	const files = `
go 1.14
-- lib/a.go --
package lib

const A = 1

-- main.go --
package main

import (
	"mod.com/lib"
)

func main() {
	println("Hello")
}
`
	const wantErr = "can't rename package: missing module information for package"
	Run(t, files, func(t *testing.T, env *Env) {
		loc := env.RegexpSearch("lib/a.go", "lib")
		params := &protocol.PrepareRenameParams{
			TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		}
		_, err := env.Editor.Server.PrepareRename(env.Ctx, params)
		if err == nil || !strings.Contains(err.Error(), wantErr) {
			t.Errorf("missing cannot rename packages with unknown module from PrepareRename")
		}
	})
}

// This test ensures that each import of a renamed package
// is also renamed if it would otherwise create a conflict.
func TestRenamePackageWithConflicts(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/nested/a.go --
package nested

const B = 1

-- lib/x/a.go --
package nested1

const C = 1

-- main.go --
package main

import (
	"mod.com/lib"
	"mod.com/lib/nested"
	nested1 "mod.com/lib/x"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		// Don't rename subpackages.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", `nested2 "mod.com/nested"`)
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", "mod.com/lib/nested")
		env.RegexpSearch("main.go", `nested1 "mod.com/lib/x"`)
	})

	WithOptions(Settings{"renameMovesSubpackages": true}).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		// Rename subpackages.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", `nested2 "mod.com/nested"`)
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", "mod.com/nested/nested")
		env.RegexpSearch("main.go", `nested1 "mod.com/nested/x"`)
	})
}

func TestRenamePackageWithAlias(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/nested/a.go --
package nested

const B = 1

-- main.go --
package main

import (
	"mod.com/lib"
	lib1 "mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", `lib1 "mod.com/lib/nested"`)
	})
}

func TestRenamePackageWithDifferentDirectoryPath(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/nested/a.go --
package foo

const B = 1

-- main.go --
package main

import (
	"mod.com/lib"
	foo "mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		// Don't rename subpackages.
		env.RegexpSearch("main.go", `foo "mod.com/lib/nested"`)
	})

	WithOptions(Settings{"renameMovesSubpackages": true}).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		// Rename subpackages.
		env.RegexpSearch("main.go", `foo "mod.com/nested/nested"`)
	})
}

func TestRenamePackage(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/b.go --
package lib

const B = 1

-- lib/nested/a.go --
package nested

const C = 1

-- main.go --
package main

import (
	"mod.com/lib"
	"mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "lib1")

		// Check if the new package name exists.
		env.RegexpSearch("lib1/a.go", "package lib1")
		env.RegexpSearch("lib1/b.go", "package lib1")
		env.RegexpSearch("main.go", "mod.com/lib1")
		env.RegexpSearch("main.go", "mod.com/lib/nested")
	})
}

// Test for golang/go#47564.
func TestRenameInTestVariant(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- stringutil/stringutil.go --
package stringutil

func Identity(s string) string {
	return s
}
-- stringutil/stringutil_test.go --
package stringutil

func TestIdentity(t *testing.T) {
	if got := Identity("foo"); got != "foo" {
		t.Errorf("bad")
	}
}
-- main.go --
package main

import (
	"fmt"

	"mod.com/stringutil"
)

func main() {
	fmt.Println(stringutil.Identity("hello world"))
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.Rename(env.RegexpSearch("main.go", `stringutil\.(Identity)`), "Identityx")
		env.OpenFile("stringutil/stringutil_test.go")
		text := env.BufferText("stringutil/stringutil_test.go")
		if !strings.Contains(text, "Identityx") {
			t.Errorf("stringutil/stringutil_test.go: missing expected token `Identityx` after rename:\n%s", text)
		}
	})
}

// This is a test that rename operation initiated by the editor function as expected.
func TestRenameFileFromEditor(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.16
-- a/a.go --
package a

const X = 1
-- a/x.go --
package a

const X = 2
-- b/b.go --
package b
`

	Run(t, files, func(t *testing.T, env *Env) {
		// Rename files and verify that diagnostics are affected accordingly.

		// Initially, we should have diagnostics on both X's, for their duplicate declaration.
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.go", "X")),
			Diagnostics(env.AtRegexp("a/x.go", "X")),
		)

		// Moving x.go should make the diagnostic go away.
		env.RenameFile("a/x.go", "b/x.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),               // no more duplicate declarations
			Diagnostics(env.AtRegexp("b/b.go", "package")), // as package names mismatch
		)

		// Renaming should also work on open buffers.
		env.OpenFile("b/x.go")

		// Moving x.go back to a/ should cause the diagnostics to reappear.
		env.RenameFile("b/x.go", "a/x.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "X")),
			Diagnostics(env.AtRegexp("a/x.go", "X")),
		)

		// Renaming the entire directory should move both the open and closed file.
		env.RenameFile("a", "x")
		env.AfterChange(
			Diagnostics(env.AtRegexp("x/a.go", "X")),
			Diagnostics(env.AtRegexp("x/x.go", "X")),
		)

		// As a sanity check, verify that x/x.go is open.
		if text := env.BufferText("x/x.go"); text == "" {
			t.Fatal("got empty buffer for x/x.go")
		}
	})
}

func TestRenamePackage_Tests(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/b.go --
package lib

const B = 1

-- lib/a_test.go --
package lib_test

import (
	"mod.com/lib"
	"fmt
)

const C = 1

-- lib/b_test.go --
package lib

import (
	"fmt
)

const D = 1

-- lib/nested/a.go --
package nested

const D = 1

-- main.go --
package main

import (
	"mod.com/lib"
	"mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "lib1")

		// Check if the new package name exists.
		env.RegexpSearch("lib1/a.go", "package lib1")
		env.RegexpSearch("lib1/b.go", "package lib1")
		env.RegexpSearch("main.go", "mod.com/lib1")
		env.RegexpSearch("main.go", "mod.com/lib/nested")

		// Check if the test package is renamed
		env.RegexpSearch("lib1/a_test.go", "package lib1_test")
		env.RegexpSearch("lib1/b_test.go", "package lib1")
	})
}

func TestRenamePackage_NestedModule(t *testing.T) {
	const files = `
-- go.work --
go 1.18
use (
	.
	./foo/bar
	./foo/baz
)

-- go.mod --
module mod.com

go 1.18

require (
    mod.com/foo/bar v0.0.0
)

replace (
	mod.com/foo/bar => ./foo/bar
	mod.com/foo/baz => ./foo/baz
)
-- foo/foo.go --
package foo

import "fmt"

func Bar() {
	fmt.Println("In foo before renamed to foox.")
}

-- foo/bar/go.mod --
module mod.com/foo/bar

-- foo/bar/bar.go --
package bar

const Msg = "Hi from package bar"

-- foo/baz/go.mod --
module mod.com/foo/baz

-- foo/baz/baz.go --
package baz

const Msg = "Hi from package baz"

-- main.go --
package main

import (
	"fmt"
	"mod.com/foo/bar"
	"mod.com/foo/baz"
	"mod.com/foo"
)

func main() {
	foo.Bar()
	fmt.Println(bar.Msg)
	fmt.Println(baz.Msg)
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")
		env.Rename(env.RegexpSearch("foo/foo.go", "foo"), "foox")

		env.RegexpSearch("foox/foo.go", "package foox")
		// Don't rename subpackages.
		env.OpenFile("foo/bar/bar.go")
		env.OpenFile("foo/bar/go.mod")

		env.RegexpSearch("main.go", "mod.com/foo/bar")
		env.RegexpSearch("main.go", "mod.com/foox")
		env.RegexpSearch("main.go", "foox.Bar()")

		env.RegexpSearch("go.mod", "./foo/bar")
		env.RegexpSearch("go.mod", "./foo/baz")
	})

	WithOptions(Settings{"renameMovesSubpackages": true}).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")
		env.Rename(env.RegexpSearch("foo/foo.go", "foo"), "foox")

		env.RegexpSearch("foox/foo.go", "package foox")
		// Rename subpackages.
		env.OpenFile("foox/bar/bar.go")
		env.OpenFile("foox/bar/go.mod")

		env.RegexpSearch("main.go", "mod.com/foo/bar")
		env.RegexpSearch("main.go", "mod.com/foox")
		env.RegexpSearch("main.go", "foox.Bar()")

		env.RegexpSearch("go.mod", "./foox/bar")
		env.RegexpSearch("go.mod", "./foox/baz")
	})
}

func TestRenamePackage_DuplicateImport(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/nested/a.go --
package nested

const B = 1

-- main.go --
package main

import (
	"mod.com/lib"
	lib1 "mod.com/lib"
	lib2 "mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", `lib1 "mod.com/nested"`)
		// Don't rename subpackages.
		env.RegexpSearch("main.go", `lib2 "mod.com/lib/nested"`)
	})

	WithOptions(Settings{"renameMovesSubpackages": true}).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", `lib1 "mod.com/nested"`)
		// Rename subpackages.
		env.RegexpSearch("main.go", `lib2 "mod.com/nested/nested"`)
	})
}

func TestRenamePackage_DuplicateBlankImport(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

const A = 1

-- lib/nested/a.go --
package nested

const B = 1

-- main.go --
package main

import (
	"mod.com/lib"
	_ "mod.com/lib"
	lib1 "mod.com/lib/nested"
)

func main() {
	println("Hello")
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", `_ "mod.com/nested"`)
		// Don't rename subpackages.
		env.RegexpSearch("main.go", `lib1 "mod.com/lib/nested"`)
	})

	WithOptions(Settings{"renameMovesSubpackages": true}).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "nested")

		// Check if the new package name exists.
		env.RegexpSearch("nested/a.go", "package nested")
		env.RegexpSearch("main.go", "mod.com/nested")
		env.RegexpSearch("main.go", `_ "mod.com/nested"`)
		// Rename subpackages.
		env.RegexpSearch("main.go", `lib1 "mod.com/nested/nested"`)
	})
}

func TestRenamePackage_TestVariant(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo/foo.go --
package foo

const Foo = 42
-- bar/bar.go --
package bar

import "mod.com/foo"

const Bar = foo.Foo
-- bar/bar_test.go --
package bar

import "mod.com/foo"

const Baz = foo.Foo
-- testdata/bar/bar.go --
package bar

import "mod.com/foox"

const Bar = foox.Foo
-- testdata/bar/bar_test.go --
package bar

import "mod.com/foox"

const Baz = foox.Foo
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")
		env.Rename(env.RegexpSearch("foo/foo.go", "package (foo)"), "foox")

		checkTestdata(t, env)
	})
}

func TestRenamePackage_IntermediateTestVariant(t *testing.T) {
	// In this test set up, we have the following import edges:
	//   bar_test -> baz -> foo -> bar
	//   bar_test -> foo -> bar
	//   bar_test -> bar
	//
	// As a consequence, bar_x_test.go is in the reverse closure of both
	// `foo [bar.test]` and `baz [bar.test]`. This test confirms that we don't
	// produce duplicate edits in this case.
	const files = `
-- go.mod --
module foo.mod

go 1.12
-- foo/foo.go --
package foo

import "foo.mod/bar"

const Foo = 42

const _ = bar.Bar
-- baz/baz.go --
package baz

import "foo.mod/foo"

const Baz = foo.Foo
-- bar/bar.go --
package bar

var Bar = 123
-- bar/bar_test.go --
package bar

const _ = Bar
-- bar/bar_x_test.go --
package bar_test

import (
	"foo.mod/bar"
	"foo.mod/baz"
	"foo.mod/foo"
)

const _ = bar.Bar + baz.Baz + foo.Foo
-- testdata/foox/foo.go --
package foox

import "foo.mod/bar"

const Foo = 42

const _ = bar.Bar
-- testdata/baz/baz.go --
package baz

import "foo.mod/foox"

const Baz = foox.Foo
-- testdata/bar/bar_x_test.go --
package bar_test

import (
	"foo.mod/bar"
	"foo.mod/baz"
	"foo.mod/foox"
)

const _ = bar.Bar + baz.Baz + foox.Foo
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")
		env.Rename(env.RegexpSearch("foo/foo.go", "package (foo)"), "foox")

		checkTestdata(t, env)
	})
}

func TestRenamePackage_Nesting(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

import "mod.com/lib/nested"

const A = 1 + nested.B
-- lib/nested/a.go --
package nested

const B = 1
-- other/other.go --
package other

import (
	"mod.com/lib"
	"mod.com/lib/nested"
)

const C = lib.A + nested.B
-- testdata/libx/a.go --
package libx

import "mod.com/lib/nested"

const A = 1 + nested.B
-- testdata/other/other.go --
package other

import (
	"mod.com/libx"
	"mod.com/lib/nested"
)

const C = libx.A + nested.B
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "package (lib)"), "libx")

		checkTestdata(t, env)
	})
}

func TestRenamePackage_InvalidName(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

import "mod.com/lib/nested"

const A = 1 + nested.B
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/a.go")
		loc := env.RegexpSearch("lib/a.go", "package (lib)")

		for _, badName := range []string{"$$$", "lib_test"} {
			if err := env.Editor.Rename(env.Ctx, loc, badName); err == nil {
				t.Errorf("Rename(lib, libx) succeeded unexpectedly")
			}
		}
	})
}

func TestRenamePackage_InternalPackage(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- lib/a.go --
package lib

import (
	"fmt"
	"mod.com/lib/internal/x"
)

const A = 1

func print() {
	fmt.Println(x.B)
}

-- lib/internal/x/a.go --
package x

const B = 1

-- main.go --
package main

import "mod.com/lib"

func main() {
	lib.print()
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("lib/internal/x/a.go")
		env.Rename(env.RegexpSearch("lib/internal/x/a.go", "x"), "utils")

		// Check if the new package name exists.
		env.RegexpSearch("lib/a.go", "mod.com/lib/internal/utils")
		env.RegexpSearch("lib/a.go", "utils.B")

		// Check if the test package is renamed
		env.RegexpSearch("lib/internal/utils/a.go", "package utils")

		env.OpenFile("lib/a.go")
		env.Rename(env.RegexpSearch("lib/a.go", "lib"), "lib1")

		// Check if the new package name exists.
		env.RegexpSearch("lib1/a.go", "package lib1")
		// Don't rename subpackages.
		env.RegexpSearch("lib1/a.go", "mod.com/lib/internal/utils")
		env.RegexpSearch("main.go", `import "mod.com/lib1"`)
		env.RegexpSearch("main.go", "lib1.print()")
	})
}
func TestRenamePackage_InvalidPackageMove(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.21
-- test1/test1.go --
package test1

-- test2/test2.go --
package test2

`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("test1/test1.go")
		loc := env.RegexpSearch("test1/test1.go", "test1")
		for _, test := range []struct{ badName, expectedErrMatch string }{
			{"test2", "invalid package identifier"},
			{"mod.com/test2", "not empty"},
			{"differentmod.com/test2", "cannot move package across module boundary"},
			{"mod.com/$$$", "invalid package name"},
			{"mod*.$+", "invalid package path"},
			{"mod.commmm", "cannot move package across module boundary"},
		} {
			err := env.Editor.Rename(env.Ctx, loc, test.badName)
			if err == nil {
				t.Errorf("Rename to %s succeeded unexpectedly", test.badName)
			} else if !strings.Contains(err.Error(), test.expectedErrMatch) {
				t.Errorf("Rename to %s produced incorrect error message, got %s, want %s", test.badName, err.Error(), test.expectedErrMatch)
			}
		}
	})
}

// checkTestdata checks that current buffer contents match their corresponding
// expected content in the testdata directory.
func checkTestdata(t *testing.T, env *Env) {
	t.Helper()
	files := env.ListFiles("testdata")
	if len(files) == 0 {
		t.Fatal("no files in testdata directory")
	}
	for _, file := range files {
		suffix := strings.TrimPrefix(file, "testdata/")
		got := env.BufferText(suffix)
		want := env.ReadWorkspaceFile(file)
		if diff := compare.Text(want, got); diff != "" {
			t.Errorf("Rename: unexpected buffer content for %s (-want +got):\n%s", suffix, diff)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/misc/semantictokens_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"fmt"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

func TestBadURICrash_VSCodeIssue1498(t *testing.T) {
	const src = `
-- go.mod --
module example.com

go 1.12

-- main.go --
package main

func main() {}

`
	WithOptions(
		Modes(Default),
	).Run(t, src, func(t *testing.T, env *Env) {
		params := &protocol.SemanticTokensParams{}
		const badURI = "http://foo"
		params.TextDocument.URI = badURI
		// This call panicked in the past: golang/vscode-go#1498.
		_, err := env.Editor.Server.SemanticTokensFull(env.Ctx, params)

		// Requests to an invalid URI scheme now result in an LSP error.
		got := fmt.Sprint(err)
		want := `DocumentURI scheme is not 'file': http://foo`
		if !strings.Contains(got, want) {
			t.Errorf("SemanticTokensFull error is %v, want substring %q", got, want)
		}
	})
}

// fix bug involving type parameters and regular parameters
// (golang/vscode-go#2527)
func TestSemantic_2527(t *testing.T) {
	// these are the expected types of identifiers in text order
	want := []fake.SemanticToken{
		{Token: "package", TokenType: "keyword"},
		{Token: "foo", TokenType: "namespace"},
		{Token: "// comment", TokenType: "comment"},
		{Token: "func", TokenType: "keyword"},
		{Token: "Add", TokenType: "function", Mod: "definition signature"},
		{Token: "T", TokenType: "typeParameter", Mod: "definition"},
		{Token: "int", TokenType: "type", Mod: "defaultLibrary number"},
		{Token: "target", TokenType: "parameter", Mod: "definition"},
		{Token: "T", TokenType: "typeParameter"},
		{Token: "l", TokenType: "parameter", Mod: "definition slice"},
		{Token: "T", TokenType: "typeParameter"},
		{Token: "T", TokenType: "typeParameter"},
		{Token: "return", TokenType: "keyword"},
		{Token: "append", TokenType: "function", Mod: "defaultLibrary"},
		{Token: "l", TokenType: "parameter", Mod: "slice"},
		{Token: "target", TokenType: "parameter"},
		{Token: "for", TokenType: "keyword"},
		{Token: "range", TokenType: "keyword"},
		{Token: "l", TokenType: "parameter", Mod: "slice"},
		{Token: "// test coverage", TokenType: "comment"},
		{Token: "return", TokenType: "keyword"},
		{Token: "nil", TokenType: "variable", Mod: "readonly defaultLibrary"},
	}
	src := `
-- go.mod --
module example.com

go 1.19
-- main.go --
package foo
// comment
func Add[T int](target T, l []T) []T {
	return append(l, target)
	for range l {} // test coverage
	return nil
}
`
	WithOptions(
		Modes(Default),
		Settings{"semanticTokens": true},
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "for range")),
		)
		seen := env.SemanticTokensFull("main.go")
		if x := cmp.Diff(want, seen); x != "" {
			t.Errorf("Semantic tokens do not match (-want +got):\n%s", x)
		}
	})

}

// fix inconsistency in TypeParameters
// https://github.com/golang/go/issues/57619
func TestSemantic_57619(t *testing.T) {
	src := `
-- go.mod --
module example.com

go 1.19
-- main.go --
package foo
type Smap[K int, V any] struct {
	Store map[K]V
}
func (s *Smap[K, V]) Get(k K) (V, bool) {
	v, ok := s.Store[k]
	return v, ok
}
func New[K int, V any]() Smap[K, V] {
	return Smap[K, V]{Store: make(map[K]V)}
}
`
	WithOptions(
		Modes(Default),
		Settings{"semanticTokens": true},
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		seen := env.SemanticTokensFull("main.go")
		for i, s := range seen {
			if (s.Token == "K" || s.Token == "V") && s.TokenType != "typeParameter" {
				t.Errorf("%d: expected K and V to be type parameters, but got %v", i, s)
			}
		}
	})
}

func TestSemanticGoDirectives(t *testing.T) {
	src := `
-- go.mod --
module example.com

go 1.19
-- main.go --
package foo

//go:linkname now time.Now
func now()

//go:noinline
func foo() {}

// Mentioning go:noinline should not tokenize.

//go:notadirective
func bar() {}
`
	want := []fake.SemanticToken{
		{Token: "package", TokenType: "keyword"},
		{Token: "foo", TokenType: "namespace"},

		{Token: "//", TokenType: "comment"},
		{Token: "go:linkname", TokenType: "namespace"},
		{Token: "now time.Now", TokenType: "comment"},
		{Token: "func", TokenType: "keyword"},
		{Token: "now", TokenType: "function", Mod: "definition signature"},

		{Token: "//", TokenType: "comment"},
		{Token: "go:noinline", TokenType: "namespace"},
		{Token: "func", TokenType: "keyword"},
		{Token: "foo", TokenType: "function", Mod: "definition signature"},

		{Token: "// Mentioning go:noinline should not tokenize.", TokenType: "comment"},

		{Token: "//go:notadirective", TokenType: "comment"},
		{Token: "func", TokenType: "keyword"},
		{Token: "bar", TokenType: "function", Mod: "definition signature"},
	}

	WithOptions(
		Modes(Default),
		Settings{"semanticTokens": true},
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		seen := env.SemanticTokensFull("main.go")
		if x := cmp.Diff(want, seen); x != "" {
			t.Errorf("Semantic tokens do not match (-want +got):\n%s", x)
		}
	})
}

// Make sure no zero-length tokens occur
func TestSemantic_65254(t *testing.T) {
	src := `
-- go.mod --
module example.com
	
go 1.21
-- main.go --
package main

/* a comment with an

empty line
*/

const bad = `

	src += "`foo" + `
	` + "bar`"
	want := []fake.SemanticToken{
		{Token: "package", TokenType: "keyword"},
		{Token: "main", TokenType: "namespace"},
		{Token: "/* a comment with an", TokenType: "comment"},
		// --- Note that the zero length line does not show up
		{Token: "empty line", TokenType: "comment"},
		{Token: "*/", TokenType: "comment"},
		{Token: "const", TokenType: "keyword"},
		{Token: "bad", TokenType: "variable", Mod: "definition readonly"},
		{Token: "`foo", TokenType: "string"},
		// --- Note the zero length line does not show up
		{Token: "\tbar`", TokenType: "string"},
	}
	WithOptions(
		Modes(Default),
		Settings{"semanticTokens": true},
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		seen := env.SemanticTokensFull("main.go")
		if x := cmp.Diff(want, seen); x != "" {
			t.Errorf("Semantic tokens do not match (-want +got):\n%s", x)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/settings_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestEmptyDirectoryFilters_Issue51843(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
}
`

	WithOptions(
		Settings{"directoryFilters": []string{""}},
	).Run(t, src, func(t *testing.T, env *Env) {
		// No need to do anything. Issue golang/go#51843 is triggered by the empty
		// directory filter above.
	})
}


================================================
FILE: gopls/internal/test/integration/misc/shared_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Smoke test that simultaneous editing sessions in the same workspace works.
func TestSimultaneousEdits(t *testing.T) {
	const sharedProgram = `
-- go.mod --
module mod

go 1.12
-- main.go --
package main

import "fmt"

func main() {
	fmt.Println("Hello World.")
}`

	WithOptions(
		Modes(DefaultModes()&(Forwarded|SeparateProcess)),
	).Run(t, sharedProgram, func(t *testing.T, env1 *Env) {
		// Create a second test session connected to the same workspace and server
		// as the first.
		env2 := ConnectGoplsEnv(t, env1.Ctx, env1.Sandbox, env1.Editor.Config(), env1.Server)
		env2.Await(InitialWorkspaceLoad)
		// In editor #1, break fmt.Println as before.
		env1.OpenFile("main.go")
		env1.RegexpReplace("main.go", "Printl(n)", "")
		// In editor #2 remove the closing brace.
		env2.OpenFile("main.go")
		env2.RegexpReplace("main.go", "\\)\n(})", "")

		// Now check that we got different diagnostics in each environment.
		env1.AfterChange(Diagnostics(env1.AtRegexp("main.go", "Printl")))
		env2.AfterChange(Diagnostics(env2.AtRegexp("main.go", "$")))

		// Now close editor #2, and verify that operation in editor #1 is
		// unaffected.
		if err := env2.Editor.Close(env2.Ctx); err != nil {
			t.Errorf("closing second editor: %v", err)
		}

		env1.RegexpReplace("main.go", "Printl", "Println")
		env1.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/signature_help_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestSignatureHelpInNonWorkspacePackage(t *testing.T) {
	const files = `
-- a/go.mod --
module a.com

go 1.18
-- a/a/a.go --
package a

func DoSomething(int) {}

func _() {
	DoSomething()
}
-- b/go.mod --
module b.com
go 1.18

require a.com v1.0.0

replace a.com => ../a
-- b/b/b.go --
package b

import "a.com/a"

func _() {
	a.DoSomething()
}
`

	WithOptions(
		WorkspaceFolders("a"),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a/a.go")
		env.OpenFile("b/b/b.go")
		signatureHelp := func(filename string) *protocol.SignatureHelp {
			loc := env.RegexpSearch(filename, `DoSomething\(()\)`)
			var params protocol.SignatureHelpParams
			params.TextDocument.URI = loc.URI
			params.Position = loc.Range.Start
			help, err := env.Editor.Server.SignatureHelp(env.Ctx, &params)
			if err != nil {
				t.Fatal(err)
			}
			return help
		}
		ahelp := signatureHelp("a/a/a.go")
		bhelp := signatureHelp("b/b/b.go")

		if diff := cmp.Diff(ahelp, bhelp); diff != "" {
			t.Fatal(diff)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/staticcheck_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestStaticcheckGenerics(t *testing.T) {
	// CL 583778 causes buildir not to run on packages that use
	// range-over-func, since it might otherwise crash. But nearly
	// all packages will soon meet this description, so the
	// analyzers in this test will not run, and the test will fail.
	// TODO(adonovan): reenable once dominikh/go-tools#1494 is fixed.
	t.Skip("disabled until buildir supports range-over-func (dominikh/go-tools#1494)")

	const files = `
-- go.mod --
module mod.com

go 1.18
-- a/a.go --
package a

import (
	"errors"
	"sort"
	"strings"
)

func Zero[P any]() P {
	var p P
	return p
}

type Inst[P any] struct {
	Field P
}

func testGenerics[P *T, T any](p P) {
	// Calls to instantiated functions should not break checks.
	slice := Zero[string]()
	sort.Slice(slice, func(i, j int) bool {
		return slice[i] < slice[j]
	})

	// Usage of instantiated fields should not break checks.
	g := Inst[string]{"hello"}
	g.Field = strings.TrimLeft(g.Field, "12234")

	// Use of type parameters should not break checks.
	var q P
	p = q // SA4009: p is overwritten before its first use
	q = &*p // SA4001: &* will be simplified
}


// FooErr should be called ErrFoo (ST1012)
var FooErr error = errors.New("foo")
`

	WithOptions(
		Settings{"staticcheck": true},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "sort.Slice"), FromSource("sortslice")),
			Diagnostics(env.AtRegexp("a/a.go", "sort.Slice.(slice)"), FromSource("SA1028")),
			Diagnostics(env.AtRegexp("a/a.go", "var (FooErr)"), FromSource("ST1012")),
			Diagnostics(env.AtRegexp("a/a.go", `"12234"`), FromSource("SA1024")),
			Diagnostics(env.AtRegexp("a/a.go", "testGenerics.*(p P)"), FromSource("SA4009")),
			Diagnostics(env.AtRegexp("a/a.go", "q = (&\\*p)"), FromSource("SA4001")),
		)
	})
}

// Test for golang/go#56270: an analysis with related info should not panic if
// analysis.RelatedInformation.End is not set.
func TestStaticcheckRelatedInfo(t *testing.T) {
	// CL 583778 causes buildir not to run on packages that use
	// range-over-func, since it might otherwise crash. But nearly
	// all packages will soon meet this description, so the
	// analyzers in this test will not run, and the test will fail.
	// TODO(adonovan): reenable once dominikh/go-tools#1494 is fixed.
	t.Skip("disabled until buildir supports range-over-func (dominikh/go-tools#1494)")

	const files = `
-- go.mod --
module mod.test

go 1.18
-- p.go --
package p

import (
	"fmt"
)

func Foo(enabled interface{}) {
	if enabled, ok := enabled.(bool); ok {
	} else {
		_ = fmt.Sprintf("invalid type %T", enabled) // enabled is always bool here
	}
}
`

	WithOptions(
		Settings{"staticcheck": true},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("p.go", ", (enabled)"), FromSource("SA9008")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/misc/test_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

// This file defines tests of the source.test ("Run tests and
// benchmarks") code action.

import (
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestRunTestsAndBenchmarks(t *testing.T) {
	file := filepath.Join(t.TempDir(), "out")
	os.Setenv("TESTFILE", file) // ignore error

	const src = `
-- go.mod --
module example.com
go 1.19

-- a/a.go --
package a

-- a/a_test.go --
package a

import (
	"os"
	"testing"
)

func Test(t *testing.T) {
	os.WriteFile(os.Getenv("TESTFILE"), []byte("ok"), 0644)
}

`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a/a_test.go")
		loc := env.RegexpSearch("a/a_test.go", "WriteFile")

		// Request code actions. (settings.GoTest is special:
		// it is returned only when explicitly requested.)
		actions, err := env.Editor.Server.CodeAction(env.Ctx, &protocol.CodeActionParams{
			TextDocument: protocol.TextDocumentIdentifier{URI: loc.URI},
			Range:        loc.Range,
			Context: protocol.CodeActionContext{
				Only: []protocol.CodeActionKind{settings.GoTest},
			},
		})
		if err != nil {
			t.Fatal(err)
		}
		if len(actions) != 1 {
			t.Fatalf("CodeAction returned %#v, want one source.test action", actions)
		}
		if actions[0].Command == nil {
			t.Fatalf("CodeActions()[0] has no Command")
		}

		// Execute test.
		// (ExecuteCommand fails if the test fails.)
		t.Logf("Running %s...", actions[0].Title)
		env.ExecuteCommand(&protocol.ExecuteCommandParams{
			Command:   actions[0].Command.Command,
			Arguments: actions[0].Command.Arguments,
		}, nil)

		// Check test had expected side effect.
		data, err := os.ReadFile(file)
		if string(data) != "ok" {
			t.Fatalf("Test did not write expected content of %s; ReadFile returned (%q, %v)", file, data, err)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/misc/vendor_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"

	"golang.org/x/tools/gopls/internal/protocol"
)

const basicProxy = `
-- golang.org/x/hello@v1.2.3/go.mod --
module golang.org/x/hello

go 1.14
-- golang.org/x/hello@v1.2.3/hi/hi.go --
package hi

var Goodbye error
`

func TestInconsistentVendoring(t *testing.T) {
	const pkgThatUsesVendoring = `
-- go.mod --
module mod.com

go 1.14

require golang.org/x/hello v1.2.3
-- vendor/modules.txt --
-- a/a1.go --
package a

import "golang.org/x/hello/hi"

func _() {
	_ = hi.Goodbye
	var q int // hardcode a diagnostic
}
`
	WithOptions(
		Modes(Default),
		ProxyFiles(basicProxy),
		WriteGoSum("."),
	).Run(t, pkgThatUsesVendoring, func(t *testing.T, env *Env) {
		env.OpenFile("a/a1.go")
		d := &protocol.PublishDiagnosticsParams{}
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.mod", "module mod.com"), WithMessage("Inconsistent vendoring")),
			ReadDiagnostics("go.mod", d),
		)
		env.ApplyQuickFixes("go.mod", d.Diagnostics)

		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a1.go", `q int`), WithMessage("not used")),
		)
	})
}

func TestWindowsVendoring_Issue56291(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.14

require golang.org/x/hello v1.2.3
-- main.go --
package main

import "golang.org/x/hello/hi"

func main() {
	_ = hi.Goodbye
}
`
	WithOptions(
		Modes(Default),
		ProxyFiles(basicProxy),
		WriteGoSum("."),
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(NoDiagnostics())
		env.RunGoCommand("mod", "tidy")
		env.RunGoCommand("mod", "vendor")
		env.AfterChange(NoDiagnostics())
		env.RegexpReplace("main.go", `import "golang.org/x/hello/hi"`, "")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", "hi.Goodbye")),
		)
		env.SaveBuffer("main.go")
		env.AfterChange(NoDiagnostics())
	})
}


================================================
FILE: gopls/internal/test/integration/misc/vuln_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"context"
	"encoding/json"
	"fmt"
	"sort"
	"strings"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/server"
	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/vulntest"
)

func TestRunGovulncheckError(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo.go --
package foo
`
	Run(t, files, func(t *testing.T, env *Env) {
		cmd := command.NewRunGovulncheckCommand("Run Vulncheck Exp", command.VulncheckArgs{
			URI: "/invalid/file/url", // invalid arg
		})
		params := &protocol.ExecuteCommandParams{
			Command:   command.RunGovulncheck.String(),
			Arguments: cmd.Arguments,
		}

		var result any
		err := env.Editor.ExecuteCommand(env.Ctx, params, &result)
		// We want an error!
		if err == nil {
			t.Errorf("got success, want invalid file URL error. Result: %v", result)
		}
	})
}

func TestVulncheckError(t *testing.T) {
	// This test checks an error of the gopls.vulncheck command, which should be
	// returned synchronously.

	const files = `
-- go.mod --
module mod.com

go 1.12
-- foo.go --
package foo

func F() { // build error incomplete
`
	WithOptions(
		EnvVars{
			"_GOPLS_TEST_BINARY_RUN_AS_GOPLS": "true", // needed to run `gopls vulncheck`.
		},
		Settings{
			"codelenses": map[string]bool{
				"run_govulncheck": true,
				"vulncheck":       true,
			},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		var result command.VulncheckResult
		err := env.Editor.ExecuteCodeLensCommand(env.Ctx, "go.mod", command.Vulncheck, &result)
		if err == nil {
			t.Fatalf("govulncheck succeeded unexpectedly: %v", result)
		}
		var ws WorkStatus
		env.Await(
			CompletedProgress(server.GoVulncheckCommandTitle, &ws),
		)
		wantEndMsg, wantMsgPart := "failed", "There are errors with the provided package patterns:"
		if ws.EndMsg != "failed" || !strings.Contains(ws.Msg, wantMsgPart) || !strings.Contains(err.Error(), wantMsgPart) {
			t.Errorf("work status = %+v, want {EndMessage: %q, Message: %q}", ws, wantEndMsg, wantMsgPart)
		}
	})
}

const vulnsData = `
-- GO-2022-01.yaml --
modules:
  - module: golang.org/amod
    versions:
      - introduced: 1.0.0
      - fixed: 1.0.4
    packages:
      - package: golang.org/amod/avuln
        symbols:
          - VulnData.Vuln1
          - VulnData.Vuln2
description: >
    vuln in amod is found
summary: vuln in amod
references:
  - href: pkg.go.dev/vuln/GO-2022-01
-- GO-2022-03.yaml --
modules:
  - module: golang.org/amod
    versions:
      - introduced: 1.0.0
      - fixed: 1.0.6
    packages:
      - package: golang.org/amod/avuln
        symbols:
          - nonExisting
description: >
  unaffecting vulnerability is found
summary: unaffecting vulnerability
-- GO-2022-02.yaml --
modules:
  - module: golang.org/bmod
    packages:
      - package: golang.org/bmod/bvuln
        symbols:
          - Vuln
description: |
    vuln in bmod is found.
    
    This is a long description
    of this vulnerability.
summary: vuln in bmod (no fix)
references:
  - href: pkg.go.dev/vuln/GO-2022-03
-- GO-2022-04.yaml --
modules:
  - module: golang.org/bmod
    packages:
      - package: golang.org/bmod/unused
        symbols:
          - Vuln
description: |
    vuln in bmod/somethingelse is found
summary: vuln in bmod/somethingelse
references:
  - href: pkg.go.dev/vuln/GO-2022-04
-- GOSTDLIB.yaml --
modules:
  - module: stdlib
    versions:
      - introduced: 1.18.0
    packages:
      - package: archive/zip
        symbols:
          - OpenReader
summary: vuln in GOSTDLIB
references:
  - href: pkg.go.dev/vuln/GOSTDLIB
`

func TestRunGovulncheckStd(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.19
-- main.go --
package main

import (
        "archive/zip"
        "fmt"
)

func main() {
        _, err := zip.OpenReader("file.zip")  // vulnerability id: GOSTDLIB
        fmt.Println(err)
}
`

	db, err := vulntest.NewDatabase(context.Background(), []byte(vulnsData))
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()

	for _, legacy := range []bool{false, true} {
		t.Run(fmt.Sprintf("legacy=%v", legacy), func(t *testing.T) {
			lenses := map[string]bool{"vulncheck": !legacy, "run_govulncheck": legacy}
			WithOptions(
				EnvVars{
					// Let the analyzer read vulnerabilities data from the testdata/vulndb.
					"GOVULNDB": db.URI(),
					// When fetchinging stdlib package vulnerability info,
					// behave as if our go version is go1.19 for this testing.
					// The default behavior is to run `go env GOVERSION` (which isn't mutable env var).
					cache.GoVersionForVulnTest:        "go1.19",
					"_GOPLS_TEST_BINARY_RUN_AS_GOPLS": "true", // needed to run `gopls vulncheck`.
				},
				Settings{
					"codelenses": lenses,
				},
			).Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("go.mod")

				// Run Command included in the codelens.

				var result *vulncheck.Result
				var expectation Expectation
				if legacy {
					var r command.RunVulncheckResult
					env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &r)
					expectation = CompletedProgressToken(r.Token, nil)
				} else {
					var r command.VulncheckResult
					env.ExecuteCodeLensCommand("go.mod", command.Vulncheck, &r)
					result = r.Result
					expectation = CompletedProgress(server.GoVulncheckCommandTitle, nil)
				}

				env.OnceMet(
					expectation,
					ShownMessage("Found GOSTDLIB"),
					NoDiagnostics(ForFile("go.mod")),
				)
				testFetchVulncheckResult(t, env, "go.mod", result, map[string]fetchVulncheckResult{
					"go.mod": {IDs: []string{"GOSTDLIB"}, Mode: vulncheck.ModeGovulncheck},
				})
			})
		})
	}
}

func TestFetchVulncheckResultStd(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

import (
        "archive/zip"
        "fmt"
)

func main() {
        _, err := zip.OpenReader("file.zip")  // vulnerability id: GOSTDLIB
        fmt.Println(err)
}
`

	db, err := vulntest.NewDatabase(context.Background(), []byte(vulnsData))
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()
	WithOptions(
		EnvVars{
			// Let the analyzer read vulnerabilities data from the testdata/vulndb.
			"GOVULNDB": db.URI(),
			// When fetchinging stdlib package vulnerability info,
			// behave as if our go version is go1.18 for this testing.
			cache.GoVersionForVulnTest:        "go1.18",
			"_GOPLS_TEST_BINARY_RUN_AS_GOPLS": "true", // needed to run `gopls vulncheck`.
		},
		Settings{"ui.diagnostic.vulncheck": "Imports"},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.AfterChange(
			NoDiagnostics(ForFile("go.mod")),
			// we don't publish diagnostics for standard library vulnerability yet.
		)
		testFetchVulncheckResult(t, env, "", nil, map[string]fetchVulncheckResult{
			"go.mod": {
				IDs:  []string{"GOSTDLIB"},
				Mode: vulncheck.ModeImports,
			},
		})
	})
}

// fetchVulncheckResult summarizes a vulncheck result for a single file.
type fetchVulncheckResult struct {
	IDs  []string
	Mode vulncheck.AnalysisMode
}

// testFetchVulncheckResult checks that calling gopls.fetch_vulncheck_result
// returns the expected summarized results contained in the want argument.
//
// If fromRun is non-nil, it is the result of running running vulncheck for
// runPath, and testFetchVulncheckResult also checks that the fetched result
// for runPath matches fromRun.
//
// This awkward factoring is an artifact of a transition from fetching
// vulncheck results asynchronously, to allowing the command to run
// asynchronously, yet returning the result synchronously from the client's
// perspective.
//
// TODO(rfindley): once VS Code no longer depends on fetching results
// asynchronously, we can remove gopls.fetch_vulncheck_result, and simplify or
// remove this helper.
func testFetchVulncheckResult(t *testing.T, env *Env, runPath string, fromRun *vulncheck.Result, want map[string]fetchVulncheckResult) {
	t.Helper()

	var result map[protocol.DocumentURI]*vulncheck.Result
	fetchCmd := command.NewFetchVulncheckResultCommand("fetch", command.URIArg{
		URI: env.Sandbox.Workdir.URI("go.mod"),
	})
	env.ExecuteCommand(&protocol.ExecuteCommandParams{
		Command:   fetchCmd.Command,
		Arguments: fetchCmd.Arguments,
	}, &result)

	for _, v := range want {
		sort.Strings(v.IDs)
	}
	summarize := func(r *vulncheck.Result) fetchVulncheckResult {
		osv := map[string]bool{}
		for _, v := range r.Findings {
			osv[v.OSV] = true
		}
		ids := make([]string, 0, len(osv))
		for id := range osv {
			ids = append(ids, id)
		}
		sort.Strings(ids)
		return fetchVulncheckResult{
			IDs:  ids,
			Mode: r.Mode,
		}
	}
	got := map[string]fetchVulncheckResult{}
	for k, r := range result {
		modfile := env.Sandbox.Workdir.RelPath(k.Path())
		got[modfile] = summarize(r)
	}
	if fromRun != nil {
		if diff := cmp.Diff(want, got); diff != "" {
			t.Errorf("fetch vulncheck result = got %v, want %v: diff %v", got, want, diff)
		}
		if diff := cmp.Diff(summarize(fromRun), got[runPath]); diff != "" {
			t.Errorf("fetched vulncheck result differs from returned (-returned, +fetched):\n%s", diff)
		}
	}
}

const workspace1 = `
-- go.mod --
module golang.org/entry

go 1.18

require golang.org/cmod v1.1.3

require (
	golang.org/amod v1.0.0 // indirect
	golang.org/bmod v0.5.0 // indirect
)
-- x/x.go --
package x

import 	(
   "golang.org/cmod/c"
   "golang.org/entry/y"
)

func X() {
	c.C1().Vuln1() // vuln use: X -> Vuln1
}

func CallY() {
	y.Y()  // vuln use: CallY -> y.Y -> bvuln.Vuln 
}

-- y/y.go --
package y

import "golang.org/cmod/c"

func Y() {
	c.C2()() // vuln use: Y -> bvuln.Vuln
}
`

// cmod/c imports amod/avuln and bmod/bvuln.
const proxy1 = `
-- golang.org/cmod@v1.1.3/go.mod --
module golang.org/cmod

go 1.12
-- golang.org/cmod@v1.1.3/c/c.go --
package c

import (
	"golang.org/amod/avuln"
	"golang.org/bmod/bvuln"
)

type I interface {
	Vuln1()
}

func C1() I {
	v := avuln.VulnData{}
	v.Vuln2() // vuln use
	return v
}

func C2() func() {
	return bvuln.Vuln
}
-- golang.org/amod@v1.0.0/go.mod --
module golang.org/amod

go 1.14
-- golang.org/amod@v1.0.0/avuln/avuln.go --
package avuln

type VulnData struct {}
func (v VulnData) Vuln1() {}
func (v VulnData) Vuln2() {}
-- golang.org/amod@v1.0.4/go.mod --
module golang.org/amod

go 1.14
-- golang.org/amod@v1.0.4/avuln/avuln.go --
package avuln

type VulnData struct {}
func (v VulnData) Vuln1() {}
func (v VulnData) Vuln2() {}

-- golang.org/bmod@v0.5.0/go.mod --
module golang.org/bmod

go 1.14
-- golang.org/bmod@v0.5.0/bvuln/bvuln.go --
package bvuln

func Vuln() {
	// something evil
}
-- golang.org/bmod@v0.5.0/unused/unused.go --
package unused

func Vuln() {
	// something evil
}
-- golang.org/amod@v1.0.6/go.mod --
module golang.org/amod

go 1.14
-- golang.org/amod@v1.0.6/avuln/avuln.go --
package avuln

type VulnData struct {}
func (v VulnData) Vuln1() {}
func (v VulnData) Vuln2() {}
`

func vulnTestEnv(proxyData string) (*vulntest.DB, []RunOption, error) {
	db, err := vulntest.NewDatabase(context.Background(), []byte(vulnsData))
	if err != nil {
		return nil, nil, nil
	}
	settings := Settings{
		"codelenses": map[string]bool{
			"run_govulncheck": true,
		},
	}
	ev := EnvVars{
		// Let the analyzer read vulnerabilities data from the testdata/vulndb.
		"GOVULNDB": db.URI(),
		// When fetching stdlib package vulnerability info,
		// behave as if our go version is go1.18 for this testing.
		// The default behavior is to run `go env GOVERSION` (which isn't mutable env var).
		cache.GoVersionForVulnTest:        "go1.18",
		"_GOPLS_TEST_BINARY_RUN_AS_GOPLS": "true", // needed to run `gopls vulncheck`.
		"GOSUMDB":                         "off",
	}
	return db, []RunOption{ProxyFiles(proxyData), ev, settings, WriteGoSum(".")}, nil
}

func TestRunVulncheckPackageDiagnostics(t *testing.T) {
	db, opts0, err := vulnTestEnv(proxy1)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()

	checkVulncheckDiagnostics := func(env *Env, t *testing.T) {
		env.OpenFile("go.mod")

		gotDiagnostics := &protocol.PublishDiagnosticsParams{}
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.mod", `golang.org/amod`)),
			ReadDiagnostics("go.mod", gotDiagnostics),
		)

		testFetchVulncheckResult(t, env, "", nil, map[string]fetchVulncheckResult{
			"go.mod": {
				IDs:  []string{"GO-2022-01", "GO-2022-02", "GO-2022-03"},
				Mode: vulncheck.ModeImports,
			},
		})

		wantVulncheckDiagnostics := map[string]vulnDiagExpectation{
			"golang.org/amod": {
				diagnostics: []vulnDiag{
					{
						msg:      "golang.org/amod has known vulnerabilities GO-2022-01, GO-2022-03.",
						severity: protocol.SeverityInformation,
						source:   string(cache.Vulncheck),
						codeActions: []string{
							"Run govulncheck to verify",
							"Upgrade to v1.0.6",
							"Upgrade to latest",
						},
					},
				},
				codeActions: []string{
					"Run govulncheck to verify",
					"Upgrade to v1.0.6",
					"Upgrade to latest",
				},
				hover: []string{"GO-2022-01", "Fixed in v1.0.4.", "GO-2022-03"},
			},
			"golang.org/bmod": {
				diagnostics: []vulnDiag{
					{
						msg:      "golang.org/bmod has a vulnerability GO-2022-02.",
						severity: protocol.SeverityInformation,
						source:   string(cache.Vulncheck),
						codeActions: []string{
							"Run govulncheck to verify",
						},
					},
				},
				codeActions: []string{
					"Run govulncheck to verify",
				},
				hover: []string{"GO-2022-02", "vuln in bmod (no fix)", "No fix is available."},
			},
		}

		for pattern, want := range wantVulncheckDiagnostics {
			modPathDiagnostics := testVulnDiagnostics(t, env, pattern, want, gotDiagnostics)

			gotActions := env.CodeActionForFile("go.mod", modPathDiagnostics)
			if diff := diffCodeActions(gotActions, want.codeActions); diff != "" {
				t.Errorf("code actions for %q do not match, got %v, want %v\n%v\n", pattern, gotActions, want.codeActions, diff)
				continue
			}
		}
	}

	wantNoVulncheckDiagnostics := func(env *Env, t *testing.T) {
		env.OpenFile("go.mod")

		gotDiagnostics := &protocol.PublishDiagnosticsParams{}
		env.AfterChange(
			ReadDiagnostics("go.mod", gotDiagnostics),
		)

		if len(gotDiagnostics.Diagnostics) > 0 {
			t.Errorf("Unexpected diagnostics: %v", stringify(gotDiagnostics))
		}
		testFetchVulncheckResult(t, env, "", nil, map[string]fetchVulncheckResult{})
	}

	for _, tc := range []struct {
		name            string
		setting         Settings
		wantDiagnostics bool
	}{
		{"imports", Settings{"ui.diagnostic.vulncheck": "Imports"}, true},
		{"default", Settings{}, false},
		{"invalid", Settings{"ui.diagnostic.vulncheck": "invalid"}, false},
	} {
		t.Run(tc.name, func(t *testing.T) {
			// override the settings options to enable diagnostics
			opts := append(opts0, tc.setting)
			WithOptions(opts...).Run(t, workspace1, func(t *testing.T, env *Env) {
				// TODO(hyangah): implement it, so we see GO-2022-01, GO-2022-02, and GO-2022-03.
				// Check that the actions we get when including all diagnostics at a location return the same result
				if tc.wantDiagnostics {
					checkVulncheckDiagnostics(env, t)
				} else {
					wantNoVulncheckDiagnostics(env, t)
				}

				if tc.name == "imports" && tc.wantDiagnostics {
					// test we get only govulncheck-based diagnostics after "run govulncheck".
					var result command.RunVulncheckResult
					env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &result)
					gotDiagnostics := &protocol.PublishDiagnosticsParams{}
					env.OnceMet(
						CompletedProgressToken(result.Token, nil),
						ShownMessage("Found"),
					)
					env.OnceMet(
						Diagnostics(env.AtRegexp("go.mod", "golang.org/bmod")),
						ReadDiagnostics("go.mod", gotDiagnostics),
					)
					// We expect only one diagnostic for GO-2022-02.
					count := 0
					for _, diag := range gotDiagnostics.Diagnostics {
						if strings.Contains(diag.Message, "GO-2022-02") {
							count++
							if got, want := diag.Severity, protocol.SeverityWarning; got != want {
								t.Errorf("Diagnostic for GO-2022-02 = %v, want %v", got, want)
							}
						}
					}
					if count != 1 {
						t.Errorf("Unexpected number of diagnostics about GO-2022-02 = %v, want 1:\n%+v", count, stringify(gotDiagnostics))
					}
				}
			})
		})
	}
}

// TestRunGovulncheck_Expiry checks that govulncheck results expire after a
// certain amount of time.
func TestRunGovulncheck_Expiry(t *testing.T) {
	// For this test, set the max age to a duration smaller than the sleep below.
	defer func(prev time.Duration) {
		cache.MaxGovulncheckResultAge = prev
	}(cache.MaxGovulncheckResultAge)
	cache.MaxGovulncheckResultAge = 99 * time.Millisecond

	db, opts0, err := vulnTestEnv(proxy1)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()

	WithOptions(opts0...).Run(t, workspace1, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.OpenFile("x/x.go")

		var result command.RunVulncheckResult
		env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &result)
		env.OnceMet(
			CompletedProgressToken(result.Token, nil),
			ShownMessage("Found"),
		)
		// Sleep long enough for the results to expire.
		time.Sleep(100 * time.Millisecond)
		// Make an arbitrary edit to force re-diagnosis of the workspace.
		env.RegexpReplace("x/x.go", "package x", "package x ")
		env.AfterChange(
			NoDiagnostics(env.AtRegexp("go.mod", "golang.org/bmod")),
		)
	})
}

func stringify(a any) string {
	data, _ := json.Marshal(a)
	return string(data)
}

func TestRunVulncheckWarning(t *testing.T) {
	db, opts, err := vulnTestEnv(proxy1)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()
	WithOptions(opts...).Run(t, workspace1, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")

		var result command.RunVulncheckResult
		env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &result)
		gotDiagnostics := &protocol.PublishDiagnosticsParams{}
		env.OnceMet(
			CompletedProgressToken(result.Token, nil),
			ShownMessage("Found"),
		)
		// Vulncheck diagnostics asynchronous to the vulncheck command.
		env.OnceMet(
			Diagnostics(env.AtRegexp("go.mod", `golang.org/amod`)),
			ReadDiagnostics("go.mod", gotDiagnostics),
		)

		testFetchVulncheckResult(t, env, "go.mod", nil, map[string]fetchVulncheckResult{
			// All vulnerabilities (symbol-level, import-level, module-level) are reported.
			"go.mod": {IDs: []string{"GO-2022-01", "GO-2022-02", "GO-2022-03", "GO-2022-04"}, Mode: vulncheck.ModeGovulncheck},
		})
		env.OpenFile("x/x.go")
		env.OpenFile("y/y.go")
		wantDiagnostics := map[string]vulnDiagExpectation{
			"golang.org/amod": {
				applyAction: "Upgrade to v1.0.6",
				diagnostics: []vulnDiag{
					{
						msg:      "golang.org/amod has a vulnerability used in the code: GO-2022-01.",
						severity: protocol.SeverityWarning,
						source:   string(cache.Govulncheck),
						codeActions: []string{
							"Upgrade to v1.0.4",
							"Upgrade to latest",
							"Reset govulncheck result",
						},
					},
					{
						msg:      "golang.org/amod has a vulnerability GO-2022-03 that is not used in the code.",
						severity: protocol.SeverityInformation,
						source:   string(cache.Govulncheck),
						codeActions: []string{
							"Upgrade to v1.0.6",
							"Upgrade to latest",
							"Reset govulncheck result",
						},
					},
				},
				codeActions: []string{
					"Upgrade to v1.0.6",
					"Upgrade to latest",
					"Reset govulncheck result",
				},
				hover: []string{"GO-2022-01", "Fixed in v1.0.4.", "GO-2022-03"},
			},
			"golang.org/bmod": {
				diagnostics: []vulnDiag{
					{
						msg:      "golang.org/bmod has a vulnerability used in the code: GO-2022-02.",
						severity: protocol.SeverityWarning,
						source:   string(cache.Govulncheck),
						codeActions: []string{
							"Reset govulncheck result", // no fix, but we should give an option to reset.
						},
					},
				},
				codeActions: []string{
					"Reset govulncheck result", // no fix, but we should give an option to reset.
				},
				hover: []string{"GO-2022-02", "vuln in bmod (no fix)", "No fix is available."},
			},
		}

		for mod, want := range wantDiagnostics {
			modPathDiagnostics := testVulnDiagnostics(t, env, mod, want, gotDiagnostics)

			// Check that the actions we get when including all diagnostics at a location return the same result
			gotActions := env.CodeActionForFile("go.mod", modPathDiagnostics)
			if diff := diffCodeActions(gotActions, want.codeActions); diff != "" {
				t.Errorf("code actions for %q do not match, expected %v, got %v\n%v\n", mod, want.codeActions, gotActions, diff)
				continue
			}

			// Apply the code action matching applyAction.
			if want.applyAction == "" {
				continue
			}
			for _, action := range gotActions {
				if action.Title == want.applyAction {
					env.ApplyCodeAction(action)
					break
				}
			}
		}

		env.Await(env.DoneWithChangeWatchedFiles())
		wantGoMod := `module golang.org/entry

go 1.18

require golang.org/cmod v1.1.3

require (
	golang.org/amod v1.0.6 // indirect
	golang.org/bmod v0.5.0 // indirect
)
`
		if got := env.BufferText("go.mod"); got != wantGoMod {
			t.Fatalf("go.mod vulncheck fix failed:\n%s", compare.Text(wantGoMod, got))
		}
	})
}

func diffCodeActions(gotActions []protocol.CodeAction, want []string) string {
	var gotTitles []string
	for _, ca := range gotActions {
		gotTitles = append(gotTitles, ca.Title)
	}
	return cmp.Diff(want, gotTitles)
}

const workspace2 = `
-- go.mod --
module golang.org/entry

go 1.18

require golang.org/bmod v0.5.0

-- x/x.go --
package x

import "golang.org/bmod/bvuln"

func F() {
	// Calls a benign func in bvuln.
	bvuln.OK()
}
`

const proxy2 = `
-- golang.org/bmod@v0.5.0/bvuln/bvuln.go --
package bvuln

func Vuln() {} // vulnerable.
func OK() {} // ok.
`

func TestGovulncheckInfo(t *testing.T) {
	db, opts, err := vulnTestEnv(proxy2)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()
	WithOptions(opts...).Run(t, workspace2, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		var result command.RunVulncheckResult
		env.ExecuteCodeLensCommand("go.mod", command.RunGovulncheck, &result)
		gotDiagnostics := &protocol.PublishDiagnosticsParams{}
		env.OnceMet(
			CompletedProgressToken(result.Token, nil),
			ShownMessage("No vulnerabilities found"), // only count affecting vulnerabilities.
		)

		// Vulncheck diagnostics asynchronous to the vulncheck command.
		env.OnceMet(
			Diagnostics(env.AtRegexp("go.mod", "golang.org/bmod")),
			ReadDiagnostics("go.mod", gotDiagnostics),
		)

		testFetchVulncheckResult(t, env, "go.mod", nil, map[string]fetchVulncheckResult{
			"go.mod": {IDs: []string{"GO-2022-02", "GO-2022-04"}, Mode: vulncheck.ModeGovulncheck},
		})
		// wantDiagnostics maps a module path in the require
		// section of a go.mod to diagnostics that will be returned
		// when running vulncheck.
		wantDiagnostics := map[string]vulnDiagExpectation{
			"golang.org/bmod": {
				diagnostics: []vulnDiag{
					{
						msg:      "golang.org/bmod has a vulnerability GO-2022-02 that is not used in the code.",
						severity: protocol.SeverityInformation,
						source:   string(cache.Govulncheck),
						codeActions: []string{
							"Reset govulncheck result",
						},
					},
				},
				codeActions: []string{
					"Reset govulncheck result",
				},
				hover: []string{"GO-2022-02", "vuln in bmod (no fix)", "No fix is available."},
			},
		}

		var allActions []protocol.CodeAction
		for mod, want := range wantDiagnostics {
			modPathDiagnostics := testVulnDiagnostics(t, env, mod, want, gotDiagnostics)
			// Check that the actions we get when including all diagnostics at a location return the same result
			gotActions := env.CodeActionForFile("go.mod", modPathDiagnostics)
			allActions = append(allActions, gotActions...)
			if diff := diffCodeActions(gotActions, want.codeActions); diff != "" {
				t.Errorf("code actions for %q do not match, expected %v, got %v\n%v\n", mod, want.codeActions, gotActions, diff)
				continue
			}
		}

		// Clear Diagnostics by using one of the reset code actions.
		var reset protocol.CodeAction
		for _, a := range allActions {
			if a.Title == "Reset govulncheck result" {
				reset = a
				break
			}
		}
		if reset.Title != "Reset govulncheck result" {
			t.Errorf("failed to find a 'Reset govulncheck result' code action, got %v", allActions)
		}
		env.ApplyCodeAction(reset)

		env.Await(NoDiagnostics(ForFile("go.mod")))
	})
}

// testVulnDiagnostics finds the require or module statement line for the requireMod in go.mod file
// and runs checks if diagnostics and code actions associated with the line match expectation.
func testVulnDiagnostics(t *testing.T, env *Env, pattern string, want vulnDiagExpectation, got *protocol.PublishDiagnosticsParams) []protocol.Diagnostic {
	t.Helper()
	loc := env.RegexpSearch("go.mod", pattern)
	var modPathDiagnostics []protocol.Diagnostic
	for _, w := range want.diagnostics {
		// Find the diagnostics at loc.start.
		var diag *protocol.Diagnostic
		for _, g := range got.Diagnostics {
			if g.Range.Start == loc.Range.Start && w.msg == g.Message {
				modPathDiagnostics = append(modPathDiagnostics, g)
				diag = &g
				break
			}
		}
		if diag == nil {
			t.Errorf("no diagnostic at %q matching %q found\n", pattern, w.msg)
			continue
		}
		if diag.Severity != w.severity || diag.Source != w.source {
			t.Errorf("incorrect (severity, source) for %q, want (%s, %s) got (%s, %s)\n", w.msg, w.severity, w.source, diag.Severity, diag.Source)
		}
		// Check expected code actions appear.
		gotActions := env.CodeActionForFile("go.mod", []protocol.Diagnostic{*diag})
		if diff := diffCodeActions(gotActions, w.codeActions); diff != "" {
			t.Errorf("code actions for %q do not match, want %v, got %v\n%v\n", w.msg, w.codeActions, gotActions, diff)
			continue
		}
	}
	// Check that useful info is supplemented as hover.
	if len(want.hover) > 0 {
		hover, _ := env.Hover(loc)
		for _, part := range want.hover {
			if !strings.Contains(hover.Value, part) {
				t.Errorf("hover contents for %q do not match, want %v, got %v\n", pattern, strings.Join(want.hover, ","), hover.Value)
				break
			}
		}
	}
	return modPathDiagnostics
}

type vulnRelatedInfo struct {
	Filename string
	Line     uint32
	Message  string
}

type vulnDiag struct {
	msg      string
	severity protocol.DiagnosticSeverity
	// codeActions is a list titles of code actions that we get with this
	// diagnostics as the context.
	codeActions []string
	// relatedInfo is related info message prefixed by the file base.
	// See summarizeRelatedInfo.
	relatedInfo []vulnRelatedInfo
	// diagnostic source.
	source string
}

// vulnDiagExpectation maps a module path in the require
// section of a go.mod to diagnostics that will be returned
// when running vulncheck.
type vulnDiagExpectation struct {
	// applyAction is the title of the code action to run for this module.
	// If empty, no code actions will be executed.
	applyAction string
	// diagnostics is the list of diagnostics we expect at the require line for
	// the module path.
	diagnostics []vulnDiag
	// codeActions is a list titles of code actions that we get with context
	// diagnostics.
	codeActions []string
	// hover message is the list of expected hover message parts for this go.mod require line.
	// all parts must appear in the hover message.
	hover []string
}


================================================
FILE: gopls/internal/test/integration/misc/workspace_symbol_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package misc

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestWorkspaceSymbolMissingMetadata(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.17
-- a.go --
package p

const K1 = "a.go"
-- exclude.go --

//go:build exclude
// +build exclude

package exclude

const K2 = "exclude.go"
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		checkSymbols(env, "K", "K1")

		// Opening up an ignored file will result in an overlay with missing
		// metadata, but this shouldn't break workspace symbols requests.
		env.OpenFile("exclude.go")
		checkSymbols(env, "K", "K1")
	})
}

func TestWorkspaceSymbolSorting(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.17
-- a/a.go --
package a

const (
	Foo = iota
	FooBar
	Fooey
	Fooex
	Fooest
)
`

	var symbolMatcher = string(settings.SymbolFastFuzzy)
	WithOptions(
		Settings{"symbolMatcher": symbolMatcher},
	).Run(t, files, func(t *testing.T, env *Env) {
		checkSymbols(env, "Foo",
			"Foo",    // prefer exact segment matches first
			"FooBar", // ...followed by exact word matches
			"Fooex",  // shorter than Fooest, FooBar, lexically before Fooey
			"Fooey",  // shorter than Fooest, Foobar
			"Fooest",
		)
	})
}

func TestWorkspaceSymbolSpecialPatterns(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.17
-- a/a.go --
package a

const (
	AxxBxxCxx
	ABC
)
`

	var symbolMatcher = string(settings.SymbolFastFuzzy)
	WithOptions(
		Settings{"symbolMatcher": symbolMatcher},
	).Run(t, files, func(t *testing.T, env *Env) {
		checkSymbols(env, "ABC", "ABC", "AxxBxxCxx")
		checkSymbols(env, "'ABC", "ABC")
		checkSymbols(env, "^mod.com", "mod.com/a.ABC", "mod.com/a.AxxBxxCxx")
		checkSymbols(env, "^mod.com Axx", "mod.com/a.AxxBxxCxx")
		checkSymbols(env, "C$", "ABC")
	})
}

func checkSymbols(env *Env, query string, want ...string) {
	env.TB.Helper()
	var got []string
	for _, info := range env.Symbol(query) {
		got = append(got, info.Name)
	}
	if diff := cmp.Diff(got, want); diff != "" {
		env.TB.Errorf("unexpected Symbol(%q) result (+want -got):\n%s", query, diff)
	}
}


================================================
FILE: gopls/internal/test/integration/modfile/modfile_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modfile

import (
	"os"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"

	"golang.org/x/tools/gopls/internal/protocol"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

const workspaceProxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

func SaySomething() {
	fmt.Println("something")
}
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/bye/bye.go --
package bye

func Goodbye() {
	println("Bye")
}
`

const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/blah/blah.go --
package hello

const Name = "Hello"
`

func TestModFileModification(t *testing.T) {
	const untidyModule = `
-- a/go.mod --
module mod.com

-- a/main.go --
package main

import "example.com/blah"

func main() {
	println(blah.Name)
}
`

	runner := RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}

	t.Run("basic", func(t *testing.T) {
		runner.Run(t, untidyModule, func(t *testing.T, env *Env) {
			// Open the file and make sure that the initial workspace load does not
			// modify the go.mod file.
			goModContent := env.ReadWorkspaceFile("a/go.mod")
			env.OpenFile("a/main.go")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/main.go", "\"example.com/blah\"")),
			)
			if got := env.ReadWorkspaceFile("a/go.mod"); got != goModContent {
				t.Fatalf("go.mod changed on disk:\n%s", compare.Text(goModContent, got))
			}
			// Save the buffer, which will format and organize imports.
			// Confirm that the go.mod file still does not change.
			env.SaveBuffer("a/main.go")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/main.go", "\"example.com/blah\"")),
			)
			if got := env.ReadWorkspaceFile("a/go.mod"); got != goModContent {
				t.Fatalf("go.mod changed on disk:\n%s", compare.Text(goModContent, got))
			}
		})
	})

	// Reproduce golang/go#40269 by deleting and recreating main.go.
	t.Run("delete main.go", func(t *testing.T) {
		runner.Run(t, untidyModule, func(t *testing.T, env *Env) {
			goModContent := env.ReadWorkspaceFile("a/go.mod")
			mainContent := env.ReadWorkspaceFile("a/main.go")
			env.OpenFile("a/main.go")
			env.SaveBuffer("a/main.go")

			// Ensure that we're done processing all the changes caused by opening
			// and saving above. If not, we may run into a file locking issue on
			// windows.
			//
			// If this proves insufficient, env.RemoveWorkspaceFile can be updated to
			// retry file lock errors on windows.
			env.AfterChange()
			env.RemoveWorkspaceFile("a/main.go")

			// TODO(rfindley): awaiting here shouldn't really be necessary. We should
			// be consistent eventually.
			//
			// Probably this was meant to exercise a race with the change below.
			env.AfterChange()

			env.WriteWorkspaceFile("a/main.go", mainContent)
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/main.go", "\"example.com/blah\"")),
			)
			if got := env.ReadWorkspaceFile("a/go.mod"); got != goModContent {
				t.Fatalf("go.mod changed on disk:\n%s", compare.Text(goModContent, got))
			}
		})
	})
}

func TestGoGetFix(t *testing.T) {
	const mod = `
-- a/go.mod --
module mod.com

go 1.12

-- a/main.go --
package main

import "example.com/blah"

var _ = blah.Name
`

	const want = `module mod.com

go 1.12

require example.com v1.2.3
`

	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, mod, func(t *testing.T, env *Env) {
		if strings.Contains(t.Name(), "workspace_module") {
			t.Skip("workspace module mode doesn't set -mod=readonly")
		}
		env.OpenFile("a/main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/main.go", `"example.com/blah"`)),
			ReadDiagnostics("a/main.go", &d),
		)
		var goGetDiag protocol.Diagnostic
		for _, diag := range d.Diagnostics {
			if strings.Contains(diag.Message, "could not import") {
				goGetDiag = diag
			}
		}
		env.ApplyQuickFixes("a/main.go", []protocol.Diagnostic{goGetDiag})
		if got := env.ReadWorkspaceFile("a/go.mod"); got != want {
			t.Fatalf("unexpected go.mod content:\n%s", compare.Text(want, got))
		}
	})
}

// Tests that multiple missing dependencies gives good single fixes.
func TestMissingDependencyFixes(t *testing.T) {
	const mod = `
-- a/go.mod --
module mod.com

go 1.12

-- a/main.go --
package main

import "example.com/blah"
import "random.org/blah"

var _, _ = blah.Name, hello.Name
`

	const want = `module mod.com

go 1.12

require random.org v1.2.3
`

	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/main.go", `"random.org/blah"`)),
			ReadDiagnostics("a/main.go", &d),
		)
		var randomDiag protocol.Diagnostic
		for _, diag := range d.Diagnostics {
			if strings.Contains(diag.Message, "random.org") {
				randomDiag = diag
			}
		}
		env.ApplyQuickFixes("a/main.go", []protocol.Diagnostic{randomDiag})
		if got := env.ReadWorkspaceFile("a/go.mod"); got != want {
			t.Fatalf("unexpected go.mod content:\n%s", compare.Text(want, got))
		}
	})
}

// Tests that multiple missing dependencies gives good single fixes.
func TestMissingDependencyFixesWithGoWork(t *testing.T) {
	const mod = `
-- go.work --
go 1.18

use (
	./a
)
-- a/go.mod --
module mod.com

go 1.12

-- a/main.go --
package main

import "example.com/blah"
import "random.org/blah"

var _, _ = blah.Name, hello.Name
`

	const want = `module mod.com

go 1.12

require random.org v1.2.3
`

	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/main.go", `"random.org/blah"`)),
			ReadDiagnostics("a/main.go", &d),
		)
		var randomDiag protocol.Diagnostic
		for _, diag := range d.Diagnostics {
			if strings.Contains(diag.Message, "random.org") {
				randomDiag = diag
			}
		}
		env.ApplyQuickFixes("a/main.go", []protocol.Diagnostic{randomDiag})
		if got := env.ReadWorkspaceFile("a/go.mod"); got != want {
			t.Fatalf("unexpected go.mod content:\n%s", compare.Text(want, got))
		}
	})
}

func TestIndirectDependencyFix(t *testing.T) {
	const mod = `
-- a/go.mod --
module mod.com

go 1.12

require example.com v1.2.3 // indirect
-- a/go.sum --
example.com v1.2.3 h1:ihBTGWGjTU3V4ZJ9OmHITkU9WQ4lGdQkMjgyLFk0FaY=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
-- a/main.go --
package main

import "example.com/blah"

func main() {
	fmt.Println(blah.Name)
`
	const want = `module mod.com

go 1.12

require example.com v1.2.3
`

	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("a/go.mod")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/go.mod", "// indirect")),
			ReadDiagnostics("a/go.mod", &d),
		)
		env.ApplyQuickFixes("a/go.mod", d.Diagnostics)
		if got := env.BufferText("a/go.mod"); got != want {
			t.Fatalf("unexpected go.mod content:\n%s", compare.Text(want, got))
		}
	})
}

// Test to reproduce golang/go#39041. It adds a new require to a go.mod file
// that already has an unused require.
func TestNewDepWithUnusedDep(t *testing.T) {

	const proxy = `
-- github.com/esimov/caire@v1.2.5/go.mod --
module github.com/esimov/caire

go 1.12
-- github.com/esimov/caire@v1.2.5/caire.go --
package caire

func RemoveTempImage() {}
-- google.golang.org/protobuf@v1.20.0/go.mod --
module google.golang.org/protobuf

go 1.12
-- google.golang.org/protobuf@v1.20.0/hello/hello.go --
package hello
`
	const repro = `
-- a/go.mod --
module mod.com

go 1.14

require google.golang.org/protobuf v1.20.0
-- a/go.sum --
github.com/esimov/caire v1.2.5 h1:OcqDII/BYxcBYj3DuwDKjd+ANhRxRqLa2n69EGje7qw=
github.com/esimov/caire v1.2.5/go.mod h1:mXnjRjg3+WUtuhfSC1rKRmdZU9vJZyS1ZWU0qSvJhK8=
google.golang.org/protobuf v1.20.0 h1:y9T1vAtFKQg0faFNMOxJU7WuEqPWolVkjIkU6aI8qCY=
google.golang.org/protobuf v1.20.0/go.mod h1:FcqsytGClbtLv1ot8NvsJHjBi0h22StKVP+K/j2liKA=
-- a/main.go --
package main

import (
    "github.com/esimov/caire"
)

func _() {
    caire.RemoveTempImage()
}`

	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, repro, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/main.go", `"github.com/esimov/caire"`)),
			ReadDiagnostics("a/main.go", &d),
		)
		env.ApplyQuickFixes("a/main.go", d.Diagnostics)
		want := `module mod.com

go 1.14

require (
	github.com/esimov/caire v1.2.5
	google.golang.org/protobuf v1.20.0
)
`
		if got := env.ReadWorkspaceFile("a/go.mod"); got != want {
			t.Fatalf("TestNewDepWithUnusedDep failed:\n%s", compare.Text(want, got))
		}
	})
}

// TODO: For this test to be effective, the sandbox's file watcher must respect
// the file watching GlobPattern in the capability registration. See
// golang/go#39384.
func TestModuleChangesOnDisk(t *testing.T) {
	const mod = `
-- a/go.mod --
module mod.com

go 1.12

require example.com v1.2.3
-- a/go.sum --
example.com v1.2.3 h1:ihBTGWGjTU3V4ZJ9OmHITkU9WQ4lGdQkMjgyLFk0FaY=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
-- a/main.go --
package main

func main() {
	fmt.Println(blah.Name)
`
	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, mod, func(t *testing.T, env *Env) {
		// With zero-config gopls, we must open a/main.go to have a View including a/go.mod.
		env.OpenFile("a/main.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/go.mod", "require")),
		)
		env.RunGoCommandInDir("a", "mod", "tidy")
		env.AfterChange(
			NoDiagnostics(ForFile("a/go.mod")),
		)
	})
}

// Tests golang/go#39784: a missing indirect dependency, necessary
// due to blah@v2.0.0's incomplete go.mod file.
func TestBadlyVersionedModule(t *testing.T) {
	const proxy = `
-- example.com/blah/@v/v1.0.0.mod --
module example.com

go 1.12
-- example.com/blah@v1.0.0/blah.go --
package blah

const Name = "Blah"
-- example.com/blah/v2/@v/v2.0.0.mod --
module example.com

go 1.12
-- example.com/blah/v2@v2.0.0/blah.go --
package blah

import "example.com/blah"

var V1Name = blah.Name
const Name = "Blah"
`
	const files = `
-- a/go.mod --
module mod.com

go 1.12

require example.com/blah/v2 v2.0.0
-- a/go.sum --
example.com/blah v1.0.0 h1:kGPlWJbMsn1P31H9xp/q2mYI32cxLnCvauHN0AVaHnc=
example.com/blah v1.0.0/go.mod h1:PZUQaGFeVjyDmAE8ywmLbmDn3fj4Ws8epg4oLuDzW3M=
example.com/blah/v2 v2.0.0 h1:DNPsFPkKtTdxclRheaMCiYAoYizp6PuBzO0OmLOO0pY=
example.com/blah/v2 v2.0.0/go.mod h1:UZiKbTwobERo/hrqFLvIQlJwQZQGxWMVY4xere8mj7w=
-- a/main.go --
package main

import "example.com/blah/v2"

var _ = blah.Name
`
	RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}.Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		env.OpenFile("a/go.mod")
		var modDiags protocol.PublishDiagnosticsParams
		env.AfterChange(
			// We would like for the error to appear in the v2 module, but
			// as of writing non-workspace packages are not diagnosed.
			Diagnostics(env.AtRegexp("a/main.go", `"example.com/blah/v2"`), WithMessage("no required module provides")),
			Diagnostics(env.AtRegexp("a/go.mod", `require example.com/blah/v2`), WithMessage("no required module provides")),
			ReadDiagnostics("a/go.mod", &modDiags),
		)

		env.ApplyQuickFixes("a/go.mod", modDiags.Diagnostics)
		const want = `module mod.com

go 1.12

require (
	example.com/blah v1.0.0 // indirect
	example.com/blah/v2 v2.0.0
)
`
		env.SaveBuffer("a/go.mod")
		env.AfterChange(NoDiagnostics(ForFile("a/main.go")))
		if got := env.BufferText("a/go.mod"); got != want {
			t.Fatalf("suggested fixes failed:\n%s", compare.Text(want, got))
		}
	})
}

// Reproduces golang/go#38232.
func TestUnknownRevision(t *testing.T) {
	if runtime.GOOS == "plan9" {
		t.Skipf("skipping test that fails for unknown reasons on plan9; see https://go.dev/issue/50477")
	}
	const unknown = `
-- a/go.mod --
module mod.com

require (
	example.com v1.2.2
)
-- a/main.go --
package main

import "example.com/blah"

func main() {
	var x = blah.Name
}
`

	runner := RunMultiple{
		{"default", WithOptions(ProxyFiles(proxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(proxy))},
	}
	// Start from a bad state/bad IWL, and confirm that we recover.
	t.Run("bad", func(t *testing.T) {
		runner.Run(t, unknown, func(t *testing.T, env *Env) {
			env.OpenFile("a/go.mod")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/go.mod", "example.com v1.2.2")),
			)
			env.RegexpReplace("a/go.mod", "v1.2.2", "v1.2.3")
			env.SaveBuffer("a/go.mod") // Save to trigger diagnostics.

			d := protocol.PublishDiagnosticsParams{}
			env.AfterChange(
				// Make sure the diagnostic mentions the new version -- the old diagnostic is in the same place.
				Diagnostics(env.AtRegexp("a/go.mod", "example.com v1.2.3"), WithMessage("example.com@v1.2.3")),
				ReadDiagnostics("a/go.mod", &d),
			)
			qfs := env.GetQuickFixes("a/go.mod", d.Diagnostics)
			if len(qfs) == 0 {
				t.Fatalf("got 0 code actions to fix %v, wanted at least 1", d.Diagnostics)
			}
			env.ApplyCodeAction(qfs[0]) // Arbitrarily pick a single fix to apply. Applying all of them seems to cause trouble in this particular test.
			env.SaveBuffer("a/go.mod")  // Save to trigger diagnostics.
			env.AfterChange(
				NoDiagnostics(ForFile("a/go.mod")),
				Diagnostics(env.AtRegexp("a/main.go", "x = ")),
			)
		})
	})

	const known = `
-- a/go.mod --
module mod.com

require (
	example.com v1.2.3
)
-- a/go.sum --
example.com v1.2.3 h1:ihBTGWGjTU3V4ZJ9OmHITkU9WQ4lGdQkMjgyLFk0FaY=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
-- a/main.go --
package main

import "example.com/blah"

func main() {
	var x = blah.Name
}
`
	// Start from a good state, transform to a bad state, and confirm that we
	// still recover.
	t.Run("good", func(t *testing.T) {
		runner.Run(t, known, func(t *testing.T, env *Env) {
			env.OpenFile("a/go.mod")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/main.go", "x = ")),
			)
			env.RegexpReplace("a/go.mod", "v1.2.3", "v1.2.2")
			env.SaveBuffer("a/go.mod") // go.mod changes must be on disk
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/go.mod", "example.com v1.2.2")),
			)
			env.RegexpReplace("a/go.mod", "v1.2.2", "v1.2.3")
			env.SaveBuffer("a/go.mod") // go.mod changes must be on disk
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/main.go", "x = ")),
			)
		})
	})
}

// Confirm that an error in an indirect dependency of a requirement is surfaced
// as a diagnostic in the go.mod file.
func TestErrorInIndirectDependency(t *testing.T) {
	const badProxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12

require random.org v1.2.3 // indirect
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.org@v1.2.3/go.mod --
module bob.org

go 1.12
-- random.org@v1.2.3/blah/blah.go --
package hello

const Name = "Hello"
`
	const module = `
-- a/go.mod --
module mod.com

go 1.14

require example.com v1.2.3
-- a/main.go --
package main

import "example.com/blah"

func main() {
	println(blah.Name)
}
`
	RunMultiple{
		{"default", WithOptions(ProxyFiles(badProxy), WorkspaceFolders("a"))},
		{"nested", WithOptions(ProxyFiles(badProxy))},
	}.Run(t, module, func(t *testing.T, env *Env) {
		env.OpenFile("a/go.mod")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/go.mod", "require example.com v1.2.3")),
		)
	})
}

// A copy of govim's config_set_env_goflags_mod_readonly test.
func TestGovimModReadonly(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.13
-- main.go --
package main

import "example.com/blah"

func main() {
	println(blah.Name)
}
`
	WithOptions(
		EnvVars{"GOFLAGS": "-mod=readonly"},
		ProxyFiles(proxy),
		Modes(Default),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		original := env.ReadWorkspaceFile("go.mod")
		env.AfterChange(
			Diagnostics(env.AtRegexp("main.go", `"example.com/blah"`)),
		)
		got := env.ReadWorkspaceFile("go.mod")
		if got != original {
			t.Fatalf("go.mod file modified:\n%s", compare.Text(original, got))
		}
		env.RunGoCommand("get", "example.com/blah@v1.2.3")
		env.RunGoCommand("mod", "tidy")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

func TestMultiModuleModDiagnostics(t *testing.T) {
	const mod = `
-- go.work --
go 1.18

use (
	a
	b
)
-- a/go.mod --
module moda.com

go 1.14

require (
	example.com v1.2.3
)
-- a/go.sum --
example.com v1.2.3 h1:Yryq11hF02fEf2JlOS2eph+ICE2/ceevGV3C9dl5V/c=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
-- a/main.go --
package main

func main() {}
-- b/go.mod --
module modb.com

require example.com v1.2.3

go 1.14
-- b/main.go --
package main

import "example.com/blah"

func main() {
	blah.SaySomething()
}
`
	WithOptions(
		ProxyFiles(workspaceProxy),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("a/go.mod", "example.com v1.2.3"),
				WithMessage("is not used"),
			),
		)
	})
}

func TestModTidyWithBuildTags(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
// +build bob

package main

import "example.com/blah"

func main() {
	blah.SaySomething()
}
`
	WithOptions(
		ProxyFiles(workspaceProxy),
		Settings{"buildFlags": []string{"-tags", "bob"}},
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", `"example.com/blah"`)),
		)
	})
}

func TestModTypoDiagnostic(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {}
`
	Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.RegexpReplace("go.mod", "module", "modul")
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.mod", "modul")),
		)
	})
}

func TestSumUpdateFixesDiagnostics(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12

require (
	example.com v1.2.3
)
-- main.go --
package main

import (
	"example.com/blah"
)

func main() {
	println(blah.Name)
}
`
	WithOptions(
		ProxyFiles(workspaceProxy),
	).Run(t, mod, func(t *testing.T, env *Env) {
		d := &protocol.PublishDiagnosticsParams{}
		env.OpenFile("go.mod")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("go.mod", `example.com v1.2.3`),
				WithMessage("go.sum is out of sync"),
			),
			ReadDiagnostics("go.mod", d),
		)
		env.ApplyQuickFixes("go.mod", d.Diagnostics)
		env.SaveBuffer("go.mod") // Save to trigger diagnostics.
		env.AfterChange(
			NoDiagnostics(ForFile("go.mod")),
		)
	})
}

// This test confirms that editing a go.mod file only causes metadata
// to be invalidated when it's saved.
func TestGoModInvalidatesOnSave(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

func main() {
	hello()
}
-- hello.go --
package main

func hello() {}
`
	WithOptions(
		// TODO(rFindley) this doesn't work in multi-module workspace mode, because
		// it keeps around the last parsing modfile. Update this test to also
		// exercise the workspace module.
		Modes(Default),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		env.Await(env.DoneWithOpen())
		env.RegexpReplace("go.mod", "module", "modul")
		// Confirm that we still have metadata with only on-disk edits.
		env.OpenFile("main.go")
		loc := env.FirstDefinition(env.RegexpSearch("main.go", "hello"))
		if loc.URI.Base() != "hello.go" {
			t.Fatalf("expected definition in hello.go, got %s", loc.URI)
		}
		// Confirm that we no longer have metadata when the file is saved.
		env.SaveBufferWithoutActions("go.mod")
		_, err := env.Editor.Definitions(env.Ctx, env.RegexpSearch("main.go", "hello"))
		if err == nil {
			t.Fatalf("expected error, got none")
		}
	})
}

func TestRemoveUnusedDependency(t *testing.T) {
	const proxy = `
-- hasdep.com@v1.2.3/go.mod --
module hasdep.com

go 1.12

require example.com v1.2.3
-- hasdep.com@v1.2.3/a/a.go --
package a
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
-- random.com@v1.2.3/go.mod --
module random.com

go 1.12
-- random.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"
`
	t.Run("almost tidied", func(t *testing.T) {
		const mod = `
-- go.mod --
module mod.com

go 1.12

require hasdep.com v1.2.3
-- main.go --
package main

func main() {}
`
		WithOptions(
			ProxyFiles(proxy),
		).Run(t, mod, func(t *testing.T, env *Env) {
			env.OpenFile("go.mod")
			d := &protocol.PublishDiagnosticsParams{}
			env.AfterChange(
				Diagnostics(env.AtRegexp("go.mod", "require hasdep.com v1.2.3")),
				ReadDiagnostics("go.mod", d),
			)
			const want = `module mod.com

go 1.12
`
			env.ApplyQuickFixes("go.mod", d.Diagnostics)
			if got := env.BufferText("go.mod"); got != want {
				t.Fatalf("unexpected content in go.mod:\n%s", compare.Text(want, got))
			}
		})
	})

	t.Run("not tidied", func(t *testing.T) {
		const mod = `
-- go.mod --
module mod.com

go 1.12

require hasdep.com v1.2.3
require random.com v1.2.3
-- main.go --
package main

func main() {}
`
		WithOptions(
			WriteGoSum("."),
			ProxyFiles(proxy),
		).Run(t, mod, func(t *testing.T, env *Env) {
			d := &protocol.PublishDiagnosticsParams{}
			env.OpenFile("go.mod")
			pos := env.RegexpSearch("go.mod", "require hasdep.com v1.2.3").Range.Start
			env.AfterChange(
				Diagnostics(AtPosition("go.mod", pos.Line, pos.Character)),
				ReadDiagnostics("go.mod", d),
			)
			const want = `module mod.com

go 1.12

require random.com v1.2.3
`
			var diagnostics []protocol.Diagnostic
			for _, d := range d.Diagnostics {
				if d.Range.Start.Line != pos.Line {
					continue
				}
				diagnostics = append(diagnostics, d)
			}
			env.ApplyQuickFixes("go.mod", diagnostics)
			if got := env.BufferText("go.mod"); got != want {
				t.Fatalf("unexpected content in go.mod:\n%s", compare.Text(want, got))
			}
		})
	})
}

func TestSumUpdateQuickFix(t *testing.T) {
	const mod = `
-- go.mod --
module mod.com

go 1.12

require (
	example.com v1.2.3
)
-- main.go --
package main

import (
	"example.com/blah"
)

func main() {
	blah.Hello()
}
`
	WithOptions(
		ProxyFiles(workspaceProxy),
		Modes(Default),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("go.mod")
		params := &protocol.PublishDiagnosticsParams{}
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("go.mod", `example.com`),
				WithMessage("go.sum is out of sync"),
			),
			ReadDiagnostics("go.mod", params),
		)
		env.ApplyQuickFixes("go.mod", params.Diagnostics)
		const want = `example.com v1.2.3 h1:Yryq11hF02fEf2JlOS2eph+ICE2/ceevGV3C9dl5V/c=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
`
		if got := env.ReadWorkspaceFile("go.sum"); got != want {
			t.Fatalf("unexpected go.sum contents:\n%s", compare.Text(want, got))
		}
	})
}

func TestDownloadDeps(t *testing.T) {
	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12

require random.org v1.2.3
-- example.com@v1.2.3/blah/blah.go --
package blah

import "random.org/bye"

func SaySomething() {
	bye.Goodbye()
}
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/bye/bye.go --
package bye

func Goodbye() {
	println("Bye")
}
`

	const mod = `
-- go.mod --
module mod.com

go 1.12
-- main.go --
package main

import (
	"example.com/blah"
)

func main() {
	blah.SaySomething()
}
`
	WithOptions(
		ProxyFiles(proxy),
		Modes(Default),
	).Run(t, mod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		d := &protocol.PublishDiagnosticsParams{}
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("main.go", `"example.com/blah"`),
				WithMessage(`could not import example.com/blah (no required module provides package "example.com/blah")`),
			),
			ReadDiagnostics("main.go", d),
		)
		env.ApplyQuickFixes("main.go", d.Diagnostics)
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
			NoDiagnostics(ForFile("go.mod")),
		)
	})
}

func TestInvalidGoVersion(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go foo
-- main.go --
package main
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("go.mod", `go foo`), WithMessage("invalid go version")),
		)
		env.WriteWorkspaceFile("go.mod", "module mod.com \n\ngo 1.12\n")
		env.AfterChange(NoDiagnostics(ForFile("go.mod")))
	})
}

// This is a regression test for a bug in the line-oriented implementation
// of the "apply diffs" operation used by the fake editor.
func TestIssue57627(t *testing.T) {
	const files = `
-- go.work --
package main
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")
		env.SetBufferContent("go.work", "go 1.18\nuse moda/a")
		env.SaveBuffer("go.work") // doesn't fail
	})
}

func TestInconsistentMod(t *testing.T) {
	const proxy = `
-- golang.org/x/mod@v0.7.0/go.mod --
go 1.20
module golang.org/x/mod
-- golang.org/x/mod@v0.7.0/a.go --
package mod
func AutoQuote(string) string { return ""}
-- golang.org/x/mod@v0.9.0/go.mod --
go 1.20
module golang.org/x/mod
-- golang.org/x/mod@v0.9.0/a.go --
package mod
func AutoQuote(string) string { return ""}
`
	const files = `
-- go.work --
go 1.20
use (
	./a
	./b
)

-- a/go.mod --
module a.mod.com
go 1.20
require golang.org/x/mod v0.6.0 // yyy
replace golang.org/x/mod v0.6.0 => golang.org/x/mod v0.7.0
-- a/main.go --
package main
import "golang.org/x/mod"
import "fmt"
func main() {fmt.Println(mod.AutoQuote(""))}

-- b/go.mod --
module b.mod.com
go 1.20
require golang.org/x/mod v0.9.0 // xxx
-- b/main.go --
package aaa
import "golang.org/x/mod"
import "fmt"
func main() {fmt.Println(mod.AutoQuote(""))}
var A int

-- b/c/go.mod --
module c.b.mod.com
go 1.20
require b.mod.com v0.4.2
replace b.mod.com => ../
-- b/c/main.go --
package main
import "b.mod.com/aaa"
import "fmt"
func main() {fmt.Println(aaa.A)}
`
	WithOptions(
		ProxyFiles(proxy),
		Modes(Default),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/go.mod")
		ahints := env.InlayHints("a/go.mod")
		if len(ahints) != 1 {
			t.Errorf("expected exactly one hint, got %d: %#v", len(ahints), ahints)
		}
		env.OpenFile("b/c/go.mod")
		bhints := env.InlayHints("b/c/go.mod")
		if len(bhints) != 0 {
			t.Errorf("expected no hints, got %d: %#v", len(bhints), bhints)
		}
	})

}


================================================
FILE: gopls/internal/test/integration/modfile/tempmodfile_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modfile

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// This test replaces an older, problematic test (golang/go#57784). But it has
// been a long time since the go command would mutate go.mod files.
//
// TODO(golang/go#61970): the tempModfile setting should be removed entirely.
func TestTempModfileUnchanged(t *testing.T) {
	// badMod has a go.mod file that is missing a go directive.
	const badMod = `
-- go.mod --
module badmod.test/p
-- p.go --
package p
`

	WithOptions(
		Modes(Default), // no reason to test this with a remote gopls
		ProxyFiles(workspaceProxy),
		Settings{
			"tempModfile": true,
		},
	).Run(t, badMod, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.AfterChange()
		want := "module badmod.test/p\n"
		got := env.ReadWorkspaceFile("go.mod")
		if got != want {
			t.Errorf("go.mod content:\n%s\nwant:\n%s", got, want)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/options.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"maps"
	"strings"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/drivertest"
)

type runConfig struct {
	editor        fake.EditorConfig
	sandbox       fake.SandboxConfig
	modes         Mode
	noLogsOnError bool
	writeGoSum    []string
}

func defaultConfig() runConfig {
	return runConfig{
		editor: fake.EditorConfig{
			Settings: map[string]any{
				// Shorten the diagnostic delay to speed up test execution (else we'd add
				// the default delay to each assertion about diagnostics)
				"diagnosticsDelay": "10ms",
			},
		},
	}
}

// A RunOption augments the behavior of the test runner.
type RunOption interface {
	set(*runConfig)
}

type optionSetter func(*runConfig)

func (f optionSetter) set(opts *runConfig) {
	f(opts)
}

// ProxyFiles configures a file proxy using the given txtar-encoded string.
func ProxyFiles(txt string) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.sandbox.ProxyFiles = fake.UnpackTxt(txt)
	})
}

// WriteGoSum causes the environment to write a go.sum file for the requested
// relative directories (via `go list -mod=mod`), before starting gopls.
//
// Useful for tests that use ProxyFiles, but don't care about crafting the
// go.sum content.
func WriteGoSum(dirs ...string) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.writeGoSum = dirs
	})
}

// Modes configures the execution modes that the test should run in.
//
// By default, modes are configured by the test runner. If this option is set,
// it overrides the set of default modes and the test runs in exactly these
// modes.
func Modes(modes Mode) RunOption {
	return optionSetter(func(opts *runConfig) {
		if opts.modes != 0 {
			panic("modes set more than once")
		}
		opts.modes = modes
	})
}

// NoLogsOnError turns off dumping the LSP logs on test failures.
func NoLogsOnError() RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.noLogsOnError = true
	})
}

// WindowsLineEndings configures the editor to use windows line endings.
func WindowsLineEndings() RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.WindowsLineEndings = true
	})
}

// ClientName sets the LSP client name.
func ClientName(name string) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.ClientName = name
	})
}

// CapabilitiesJSON sets the capabalities json.
func CapabilitiesJSON(capabilities []byte) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.CapabilitiesJSON = capabilities
	})
}

// Settings sets user-provided configuration for the LSP server.
//
// As a special case, the env setting must not be provided via Settings: use
// EnvVars instead.
type Settings map[string]any

func (s Settings) set(opts *runConfig) {
	if opts.editor.Settings == nil {
		opts.editor.Settings = make(map[string]any)
	}
	maps.Copy(opts.editor.Settings, s)
}

// WorkspaceFolders configures the workdir-relative workspace folders or uri
// to send to the LSP server. By default the editor sends a single workspace folder
// corresponding to the workdir root. To explicitly configure no workspace
// folders, use WorkspaceFolders with no arguments.
func WorkspaceFolders(relFolders ...string) RunOption {
	if len(relFolders) == 0 {
		// Use an empty non-nil slice to signal explicitly no folders.
		relFolders = []string{}
	}

	return optionSetter(func(opts *runConfig) {
		opts.editor.WorkspaceFolders = relFolders
	})
}

// NoDefaultWorkspaceFiles is used to specify whether the fake editor
// should give a default workspace folder to the LSP server.
// When it's true, the editor will pass original WorkspaceFolders to the LSP server.
func NoDefaultWorkspaceFiles() RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.NoDefaultWorkspaceFiles = true
	})
}

// RootPath configures the roo path which will be converted to rootUri and sent to the LSP server.
func RootPath(relpath string) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.RelRootPath = relpath
	})
}

// FolderSettings defines per-folder workspace settings, keyed by relative path
// to the folder.
//
// Use in conjunction with WorkspaceFolders to have different settings for
// different folders.
type FolderSettings map[string]Settings

func (fs FolderSettings) set(opts *runConfig) {
	// Re-use the Settings type, for symmetry, but translate back into maps for
	// the editor config.
	folders := make(map[string]map[string]any)
	for k, v := range fs {
		folders[k] = v
	}
	opts.editor.FolderSettings = folders
}

// EnvVars sets environment variables for the LSP session. When applying these
// variables to the session, the special string $SANDBOX_WORKDIR is replaced by
// the absolute path to the sandbox working directory.
type EnvVars map[string]string

func (e EnvVars) set(opts *runConfig) {
	if opts.editor.Env == nil {
		opts.editor.Env = make(map[string]string)
	}
	maps.Copy(opts.editor.Env, e)
}

// FakeGoPackagesDriver configures gopls to run with a fake GOPACKAGESDRIVER
// environment variable.
func FakeGoPackagesDriver(t *testing.T) RunOption {
	env := drivertest.Env(t)
	vars := make(EnvVars)
	for _, e := range env {
		kv := strings.SplitN(e, "=", 2)
		vars[kv[0]] = kv[1]
	}
	return vars
}

// InGOPATH configures the workspace working directory to be GOPATH, rather
// than a separate working directory for use with modules.
func InGOPATH() RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.sandbox.InGoPath = true
	})
}

// MessageResponder configures the editor to respond to
// window/showMessageRequest messages using the provided function.
func MessageResponder(f func(*protocol.ShowMessageRequestParams) (*protocol.MessageActionItem, error)) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.MessageResponder = f
	})
}

// DelayMessages can be used to fuzz message delivery delays for the purpose of
// reproducing test flakes.
//
// (Even though this option may be unused, keep it around to aid in debugging
// future flakes.)
func DelayMessages(upto time.Duration) RunOption {
	return optionSetter(func(opts *runConfig) {
		opts.editor.MaxMessageDelay = upto
	})
}


================================================
FILE: gopls/internal/test/integration/regtest.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"context"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/cmd"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/internal/drivertest"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/tool"
)

var (
	runSubprocessTests       = flag.Bool("enable_gopls_subprocess_tests", false, "run integration tests against a gopls subprocess (default: in-process)")
	goplsBinaryPath          = flag.String("gopls_test_binary", "", "path to the gopls binary for use as a remote, for use with the -enable_gopls_subprocess_tests flag")
	timeout                  = flag.Duration("timeout", defaultTimeout(), "if nonzero, default timeout for each integration test; defaults to GOPLS_INTEGRATION_TEST_TIMEOUT")
	skipCleanup              = flag.Bool("skip_cleanup", false, "whether to skip cleaning up temp directories")
	printGoroutinesOnFailure = flag.Bool("print_goroutines", false, "whether to print goroutines info on failure")
	printLogs                = flag.Bool("print_logs", false, "whether to print LSP logs")
)

func defaultTimeout() time.Duration {
	s := os.Getenv("GOPLS_INTEGRATION_TEST_TIMEOUT")
	if s == "" {
		return 0
	}
	d, err := time.ParseDuration(s)
	if err != nil {
		fmt.Fprintf(os.Stderr, "invalid GOPLS_INTEGRATION_TEST_TIMEOUT %q: %v\n", s, err)
		os.Exit(2)
	}
	return d
}

var runner *Runner

func Run(t *testing.T, files string, f TestFunc) {
	runner.Run(t, files, f)
}

func WithOptions(opts ...RunOption) configuredRunner {
	return configuredRunner{opts: opts}
}

type configuredRunner struct {
	opts []RunOption
}

func (r configuredRunner) Run(t *testing.T, files string, f TestFunc) {
	// Print a warning if the test's temporary directory is not
	// suitable as a workspace folder, as this may lead to
	// otherwise-cryptic failures. This situation typically occurs
	// when an arbitrary string (e.g. "foo.") is used as a subtest
	// name, on a platform with filename restrictions (e.g. no
	// trailing period on Windows).
	tmp := t.TempDir()
	if err := cache.CheckPathValid(tmp); err != nil {
		t.Logf("Warning: testing.T.TempDir(%s) is not valid as a workspace folder: %s",
			tmp, err)
	}

	runner.Run(t, files, f, r.opts...)
}

// RunMultiple runs a test multiple times, with different options.
// The runner should be constructed with [WithOptions].
//
// TODO(rfindley): replace Modes with selective use of RunMultiple.
type RunMultiple []struct {
	Name   string
	Runner interface {
		Run(t *testing.T, files string, f TestFunc)
	}
}

func (r RunMultiple) Run(t *testing.T, files string, f TestFunc) {
	for _, runner := range r {
		t.Run(runner.Name, func(t *testing.T) {
			runner.Runner.Run(t, files, f)
		})
	}
}

// DefaultModes returns the default modes to run for each regression test (they
// may be reconfigured by the tests themselves).
func DefaultModes() Mode {
	modes := Default
	if !testing.Short() {
		// TODO(rfindley): we should just run a few select integration tests in
		// "Forwarded" mode, and call it a day. No need to run every single test in
		// two ways.
		modes |= Forwarded
	}
	if *runSubprocessTests {
		modes |= SeparateProcess
	}
	return modes
}

var runFromMain = false // true if Main has been called

// Main sets up and tears down the shared integration test state.
func Main(m *testing.M) (code int) {
	// Provide an entrypoint for tests that use a fake go/packages driver.
	drivertest.RunIfChild()

	defer func() {
		if runner != nil {
			if err := runner.Close(); err != nil {
				fmt.Fprintf(os.Stderr, "closing test runner: %v\n", err)
				// Cleanup is broken in go1.12 and earlier, and sometimes flakes on
				// Windows due to file locking, but this is OK for our CI.
				//
				// Fail on go1.13+, except for windows and android which have shutdown problems.
				if testenv.Go1Point() >= 13 && runtime.GOOS != "windows" && runtime.GOOS != "android" {
					if code == 0 {
						code = 1
					}
				}
			}
		}
	}()

	runFromMain = true

	// golang/go#54461: enable additional debugging around hanging Go commands.
	gocommand.DebugHangingGoCommands = true

	// If this magic environment variable is set, run gopls instead of the test
	// suite. See the documentation for runTestAsGoplsEnvvar for more details.
	if os.Getenv(runTestAsGoplsEnvvar) == "true" {
		tool.Main(context.Background(), cmd.New(), os.Args[1:])
		return 0
	}

	if !testenv.HasExec() {
		fmt.Printf("skipping all tests: exec not supported on %s/%s\n", runtime.GOOS, runtime.GOARCH)
		return 0
	}
	testenv.ExitIfSmallMachine()

	flag.Parse()

	// Disable GOPACKAGESDRIVER, as it can cause spurious test failures.
	os.Setenv("GOPACKAGESDRIVER", "off") // ignore error

	if skipReason := checkBuilder(); skipReason != "" {
		fmt.Printf("Skipping all tests: %s\n", skipReason)
		return 0
	}

	if err := testenv.HasTool("go"); err != nil {
		fmt.Println("Missing go command")
		return 1
	}

	runner = &Runner{
		DefaultModes:             DefaultModes(),
		Timeout:                  *timeout,
		PrintGoroutinesOnFailure: *printGoroutinesOnFailure,
		SkipCleanup:              *skipCleanup,
		store:                    memoize.NewStore(memoize.NeverEvict),
	}

	runner.goplsPath = *goplsBinaryPath
	if runner.goplsPath == "" {
		var err error
		runner.goplsPath, err = os.Executable()
		if err != nil {
			panic(fmt.Sprintf("finding test binary path: %v", err))
		}
	}

	dir, err := os.MkdirTemp("", "gopls-test-")
	if err != nil {
		panic(fmt.Errorf("creating temp directory: %v", err))
	}
	runner.tempDir = dir

	FilterToolchainPathAndGOROOT()

	return m.Run()
}

// FilterToolchainPathAndGOROOT updates the PATH and GOROOT environment
// variables for the current process to effectively revert the changes made by
// the go command when performing a toolchain switch in the context of `go
// test` (see golang/go#68005).
//
// It does this by looking through PATH for a go command that is NOT a
// toolchain go command, and adjusting PATH to find that go command. Then it
// unsets GOROOT in order to use the default GOROOT for that go command.
//
// TODO(rfindley): this is very much a hack, so that our 1.21 and 1.22 builders
// actually exercise integration with older go commands. In golang/go#69321, we
// hope to do better.
func FilterToolchainPathAndGOROOT() {
	if localGo, first := findLocalGo(); localGo != "" && !first {
		dir := filepath.Dir(localGo)
		path := os.Getenv("PATH")
		os.Setenv("PATH", dir+string(os.PathListSeparator)+path) // ignore error
		os.Unsetenv("GOROOT")                                    // Remove the GOROOT value that was added by toolchain switch.
	}
}

// findLocalGo returns a path to a local (=non-toolchain) Go version, or the
// empty string if none is found.
//
// The second result reports if path matches the result of exec.LookPath.
func findLocalGo() (path string, first bool) {
	paths := filepath.SplitList(os.Getenv("PATH"))
	for _, path := range paths {
		// Use a simple heuristic to filter out toolchain paths.
		if strings.Contains(path, "toolchain@v0.0.1-go") && filepath.Base(path) == "bin" {
			continue // toolchain path
		}
		fullPath := filepath.Join(path, "go")
		fi, err := os.Stat(fullPath)
		if err != nil {
			continue
		}
		if fi.Mode()&0111 != 0 {
			first := false
			pathGo, err := exec.LookPath("go")
			if err == nil {
				first = fullPath == pathGo
			}
			return fullPath, first
		}
	}
	return "", false
}


================================================
FILE: gopls/internal/test/integration/runner.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"net"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"runtime/pprof"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/lsprpc"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/memoize"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/xcontext"
)

// Mode is a bitmask that defines for which execution modes a test should run.
//
// Each mode controls several aspects of gopls' configuration:
//   - Which server options to use for gopls sessions
//   - Whether to use a shared cache
//   - Whether to use a shared server
//   - Whether to run the server in-process or in a separate process
//
// The behavior of each mode with respect to these aspects is summarized below.
// TODO(rfindley, cleanup): rather than using arbitrary names for these modes,
// we can compose them explicitly out of the features described here, allowing
// individual tests more freedom in constructing problematic execution modes.
// For example, a test could assert on a certain behavior when running on a
// separate process. Moreover, we could unify 'Modes' with 'Options', and use
// RunMultiple rather than a hard-coded loop through modes.
//
// Mode            | Options      | Shared Cache? | Shared Server? | In-process?
// ---------------------------------------------------------------------------
// Default         | Default      | Y             | N              | Y
// Forwarded       | Default      | Y             | Y              | Y
// SeparateProcess | Default      | Y             | Y              | N
type Mode int

const (
	// Default mode runs gopls with the default options, communicating over pipes
	// to emulate the lsp sidecar execution mode, which communicates over
	// stdin/stdout.
	//
	// It uses separate servers for each test, but a shared cache, to avoid
	// duplicating work when processing GOROOT.
	Default Mode = 1 << iota

	// Forwarded uses the default options, but forwards connections to a shared
	// in-process gopls server.
	Forwarded

	// SeparateProcess uses the default options, but forwards connection to an
	// external gopls daemon.
	//
	// Only supported on GOOS=linux.
	SeparateProcess
)

func (m Mode) String() string {
	switch m {
	case Default:
		return "default"
	case Forwarded:
		return "forwarded"
	case SeparateProcess:
		return "separate process"
	default:
		return "unknown mode"
	}
}

// A Runner runs tests in gopls execution environments, as specified by its
// modes. For modes that share state (for example, a shared cache or common
// remote), any tests that execute on the same Runner will share the same
// state.
type Runner struct {
	// Configuration
	DefaultModes             Mode          // modes to run for each test
	Timeout                  time.Duration // per-test timeout, if set
	PrintGoroutinesOnFailure bool          // whether to dump goroutines on test failure
	SkipCleanup              bool          // if set, don't delete test data directories when the test exits

	// Immutable state shared across test invocations
	goplsPath string         // path to the gopls executable (for SeparateProcess mode)
	tempDir   string         // shared parent temp directory
	store     *memoize.Store // shared store

	// Lazily allocated resources
	tsOnce sync.Once
	ts     *servertest.TCPServer // shared in-process test server ("forwarded" mode)

	startRemoteOnce sync.Once
	remoteSocket    string // unix domain socket for shared daemon ("separate process" mode)
	remoteErr       error
	cancelRemote    func()
}

type TestFunc func(t *testing.T, env *Env)

// Run executes the test function in the default configured gopls execution
// modes. For each a test run, a new workspace is created containing the
// un-txtared files specified by filedata.
func (r *Runner) Run(t *testing.T, files string, test TestFunc, opts ...RunOption) {
	// TODO(rfindley): this function has gotten overly complicated, and warrants
	// refactoring.

	if !runFromMain {
		// Main performs various setup precondition checks.
		// While it could theoretically be made OK for a Runner to be used outside
		// of Main, it is simpler to enforce that we only use the Runner from
		// integration test suites.
		t.Fatal("integration.Runner.Run must be run from integration.Main")
	}

	tests := []struct {
		name      string
		mode      Mode
		getServer func() jsonrpc2.StreamServer
	}{
		{"default", Default, r.defaultServer},
		{"forwarded", Forwarded, r.forwardedServer},
		{"separate_process", SeparateProcess, r.separateProcessServer},
	}

	for _, tc := range tests {
		config := defaultConfig()
		for _, opt := range opts {
			opt.set(&config)
		}
		modes := r.DefaultModes
		if config.modes != 0 {
			modes = config.modes
		}
		if modes&tc.mode == 0 {
			continue
		}

		t.Run(tc.name, func(t *testing.T) {
			// TODO(rfindley): once jsonrpc2 shutdown is fixed, we should not leak
			// goroutines in this test function.
			// stacktest.NoLeak(t)

			ctx := context.Background()
			if r.Timeout != 0 {
				var cancel context.CancelFunc
				ctx, cancel = context.WithTimeout(ctx, r.Timeout)
				defer cancel()
			} else if d, ok := testenv.Deadline(t); ok {
				timeout := time.Until(d) * 19 / 20 // Leave an arbitrary 5% for cleanup.
				var cancel context.CancelFunc
				ctx, cancel = context.WithTimeout(ctx, timeout)
				defer cancel()
			}

			// TODO(rfindley): do we need an instance at all? Can it be removed?
			ctx = debug.WithInstance(ctx, "")

			rootDir := filepath.Join(r.tempDir, filepath.FromSlash(t.Name()))
			if err := os.MkdirAll(rootDir, 0755); err != nil {
				t.Fatal(err)
			}

			files := fake.UnpackTxt(files)
			if config.editor.WindowsLineEndings {
				for name, data := range files {
					files[name] = bytes.ReplaceAll(data, []byte("\n"), []byte("\r\n"))
				}
			}
			config.sandbox.Files = files
			config.sandbox.RootDir = rootDir
			sandbox, err := fake.NewSandbox(&config.sandbox)
			if err != nil {
				t.Fatal(err)
			}
			defer func() {
				if !r.SkipCleanup {
					if err := sandbox.Close(); err != nil {
						pprof.Lookup("goroutine").WriteTo(os.Stderr, 1) // ignore error
						t.Errorf("closing the sandbox: %v", err)
					}
				}
			}()

			// Write the go.sum file for the requested directories, before starting the server.
			for _, dir := range config.writeGoSum {
				if _, err := sandbox.RunGoCommand(context.Background(), dir, "list", []string{"-mod=mod", "./..."}, []string{"GOWORK=off"}, true); err != nil {
					t.Fatal(err)
				}
			}

			ss := tc.getServer()

			framer := jsonrpc2.NewRawStream
			ls := &loggingFramer{}
			framer = ls.framer(jsonrpc2.NewRawStream)
			ts := servertest.NewPipeServer(ss, framer)

			env := ConnectGoplsEnv(t, ctx, sandbox, config.editor, ts)
			defer func() {
				if t.Failed() && r.PrintGoroutinesOnFailure {
					pprof.Lookup("goroutine").WriteTo(os.Stderr, 1) // ignore error
				}
				if (t.Failed() && !config.noLogsOnError) || *printLogs {
					ls.printBuffers(t.Name(), os.Stderr)
				}
				// For tests that failed due to a timeout, don't fail to shutdown
				// because ctx is done.
				//
				// There is little point to setting an arbitrary timeout for closing
				// the editor: in general we want to clean up before proceeding to the
				// next test, and if there is a deadlock preventing closing it will
				// eventually be handled by the `go test` timeout.
				if err := env.Editor.Close(xcontext.Detach(ctx)); err != nil {
					t.Errorf("closing editor: %v", err)
				}
			}()
			// Always await the initial workspace load.
			env.Await(InitialWorkspaceLoad)
			test(t, env)
		})
	}
}

// ConnectGoplsEnv creates a new Gopls environment for the given sandbox,
// editor config, and server connector.
//
// TODO(rfindley): significantly refactor the way testing environments are
// constructed.
func ConnectGoplsEnv(t testing.TB, ctx context.Context, sandbox *fake.Sandbox, config fake.EditorConfig, connector servertest.Connector) *Env {
	awaiter := NewAwaiter(sandbox.Workdir)
	editor, err := fake.NewEditor(sandbox, config).Connect(ctx, connector, awaiter.Hooks())
	if err != nil {
		t.Fatal(err)
	}
	env := &Env{
		TB:      t,
		Ctx:     ctx,
		Sandbox: sandbox,
		Server:  connector,
		Editor:  editor,
		Awaiter: awaiter,
	}
	return env
}

// longBuilders maps builders that are skipped when -short is set to a
// (possibly empty) justification.
var longBuilders = map[string]string{
	"x_tools-gotip-openbsd-amd64":  "go.dev/issue/72145",
	"x_tools-go1.24-openbsd-amd64": "go.dev/issue/72145",
	"x_tools-go1.23-openbsd-amd64": "go.dev/issue/72145",

	"darwin-amd64-10_12":      "",
	"freebsd-amd64-race":      "",
	"illumos-amd64":           "",
	"netbsd-arm-bsiegert":     "",
	"solaris-amd64-oraclerel": "",
	"windows-arm-zx2c4":       "",
	"linux-ppc64le-power9osu": "go.dev/issue/66748",
}

// TODO(rfindley): inline into Main.
func checkBuilder() string {
	builder := os.Getenv("GO_BUILDER_NAME")
	if reason, ok := longBuilders[builder]; ok && testing.Short() {
		if reason != "" {
			return fmt.Sprintf("skipping %s with -short due to %s", builder, reason)
		} else {
			return fmt.Sprintf("skipping %s with -short", builder)
		}
	}
	return ""
}

type loggingFramer struct {
	mu  sync.Mutex
	buf *safeBuffer
}

// safeBuffer is a threadsafe buffer for logs.
type safeBuffer struct {
	mu  sync.Mutex
	buf bytes.Buffer
}

func (b *safeBuffer) Write(p []byte) (int, error) {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buf.Write(p)
}

func (s *loggingFramer) framer(f jsonrpc2.Framer) jsonrpc2.Framer {
	return func(nc net.Conn) jsonrpc2.Stream {
		s.mu.Lock()
		framed := false
		if s.buf == nil {
			s.buf = &safeBuffer{buf: bytes.Buffer{}}
			framed = true
		}
		s.mu.Unlock()
		stream := f(nc)
		if framed {
			return protocol.LoggingStream(stream, s.buf)
		}
		return stream
	}
}

func (s *loggingFramer) printBuffers(testname string, w io.Writer) {
	s.mu.Lock()
	defer s.mu.Unlock()

	if s.buf == nil {
		return
	}
	fmt.Fprintf(os.Stderr, "#### Start Gopls Test Logs for %q\n", testname)
	s.buf.mu.Lock()
	io.Copy(w, &s.buf.buf)
	s.buf.mu.Unlock()
	fmt.Fprintf(os.Stderr, "#### End Gopls Test Logs for %q\n", testname)
}

// defaultServer handles the Default execution mode.
func (r *Runner) defaultServer() jsonrpc2.StreamServer {
	return lsprpc.NewStreamServer(cache.New(r.store), false, nil)
}

// forwardedServer handles the Forwarded execution mode.
func (r *Runner) forwardedServer() jsonrpc2.StreamServer {
	r.tsOnce.Do(func() {
		ctx := context.Background()
		ctx = debug.WithInstance(ctx, "")
		ss := lsprpc.NewStreamServer(cache.New(nil), false, nil)
		r.ts = servertest.NewTCPServer(ctx, ss, nil)
	})
	return newForwarder("tcp", r.ts.Addr)
}

// runTestAsGoplsEnvvar triggers TestMain to run gopls instead of running
// tests. It's a trick to allow tests to find a binary to use to start a gopls
// subprocess.
const runTestAsGoplsEnvvar = "_GOPLS_TEST_BINARY_RUN_AS_GOPLS"

// separateProcessServer handles the SeparateProcess execution mode.
func (r *Runner) separateProcessServer() jsonrpc2.StreamServer {
	if runtime.GOOS != "linux" {
		panic("separate process execution mode is only supported on linux")
	}

	r.startRemoteOnce.Do(func() {
		socketDir, err := os.MkdirTemp(r.tempDir, "gopls-test-socket")
		if err != nil {
			r.remoteErr = err
			return
		}
		r.remoteSocket = filepath.Join(socketDir, "gopls-test-daemon")

		// The server should be killed by when the test runner exits, but to be
		// conservative also set a listen timeout.
		args := []string{"serve", "-listen", "unix;" + r.remoteSocket, "-listen.timeout", "1m"}

		ctx, cancel := context.WithCancel(context.Background())
		cmd := exec.CommandContext(ctx, r.goplsPath, args...)
		cmd.Env = append(os.Environ(), runTestAsGoplsEnvvar+"=true")

		// Start the external gopls process. This is still somewhat racy, as we
		// don't know when gopls binds to the socket, but the gopls forwarder
		// client has built-in retry behavior that should mostly mitigate this
		// problem (and if it doesn't, we probably want to improve the retry
		// behavior).
		if err := cmd.Start(); err != nil {
			cancel()
			r.remoteSocket = ""
			r.remoteErr = err
		} else {
			r.cancelRemote = cancel
			// Spin off a goroutine to wait, so that we free up resources when the
			// server exits.
			go cmd.Wait()
		}
	})

	return newForwarder("unix", r.remoteSocket)
}

func newForwarder(network, address string) jsonrpc2.StreamServer {
	server, err := lsprpc.NewForwarder(network+";"+address, nil)
	if err != nil {
		// This should never happen, as we are passing an explicit address.
		panic(fmt.Sprintf("internal error: unable to create forwarder: %v", err))
	}
	return server
}

// Close cleans up resource that have been allocated to this workspace.
func (r *Runner) Close() error {
	var errmsgs []string
	if r.ts != nil {
		if err := r.ts.Close(); err != nil {
			errmsgs = append(errmsgs, err.Error())
		}
	}
	if r.cancelRemote != nil {
		r.cancelRemote()
	}
	if !r.SkipCleanup {
		if err := os.RemoveAll(r.tempDir); err != nil {
			errmsgs = append(errmsgs, err.Error())
		}
	}
	if len(errmsgs) > 0 {
		return fmt.Errorf("errors closing the test runner:\n\t%s", strings.Join(errmsgs, "\n\t"))
	}
	return nil
}


================================================
FILE: gopls/internal/test/integration/template/template_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package template

import (
	"os"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

func TestMultilineTokens(t *testing.T) {
	// 51731: panic: runtime error: slice bounds out of range [38:3]
	const files = `
-- go.mod --
module mod.com

go 1.17
-- hi.tmpl --
{{if (foÜx .X.Y)}}😀{{$A := 
	"hi"
	}}{{.Z $A}}{{else}}
{{$A.X 12}}
{{foo (.X.Y) 23 ($A.Z)}}
{{end}}
`
	WithOptions(
		Settings{
			"templateExtensions": []string{"tmpl"},
			"semanticTokens":     true,
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		var p protocol.SemanticTokensParams
		p.TextDocument.URI = env.Sandbox.Workdir.URI("hi.tmpl")
		toks, err := env.Editor.Server.SemanticTokensFull(env.Ctx, &p)
		if err != nil {
			t.Errorf("semantic token failed: %v", err)
		}
		if toks == nil || len(toks.Data) == 0 {
			t.Errorf("got no semantic tokens")
		}
	})
}

func TestMultilineTokensAgain(t *testing.T) {
	// Regression tests for a crash; see go.dev/issue/74635.
	const files = `
-- go.mod --
module mod.com

go 1.17
-- hi.tmpl --
{{/* this is
a comment */}}
`
	WithOptions(
		Settings{
			"templateExtensions": []string{"tmpl"},
			"semanticTokens":     true,
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		var p protocol.SemanticTokensParams
		p.TextDocument.URI = env.Sandbox.Workdir.URI("hi.tmpl")
		toks, err := env.Editor.Server.SemanticTokensFull(env.Ctx, &p)
		if err != nil {
			t.Errorf("semantic token failed: %v", err)
		}
		if toks == nil || len(toks.Data) == 0 {
			t.Errorf("got no semantic tokens")
		}
	})
}

func TestTemplatesFromExtensions(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- hello.tmpl --
{{range .Planets}}
Hello {{}} <-- missing body
{{end}}
`
	WithOptions(
		Settings{
			"templateExtensions": []string{"tmpl"},
			"semanticTokens":     true,
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		// TODO: can we move this diagnostic onto {{}}?
		var diags protocol.PublishDiagnosticsParams
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("hello.tmpl", "()Hello {{}}")),
			ReadDiagnostics("hello.tmpl", &diags),
		)
		d := diags.Diagnostics // issue 50786: check for Source
		if len(d) != 1 {
			t.Errorf("expected 1 diagnostic, got %d", len(d))
			return
		}
		if d[0].Source != "template" {
			t.Errorf("expected Source 'template', got %q", d[0].Source)
		}
		// issue 50801 (even broken templates could return some semantic tokens)
		var p protocol.SemanticTokensParams
		p.TextDocument.URI = env.Sandbox.Workdir.URI("hello.tmpl")
		toks, err := env.Editor.Server.SemanticTokensFull(env.Ctx, &p)
		if err != nil {
			t.Errorf("semantic token failed: %v", err)
		}
		if toks == nil || len(toks.Data) == 0 {
			t.Errorf("got no semantic tokens")
		}

		env.WriteWorkspaceFile("hello.tmpl", "{{range .Planets}}\nHello {{.}}\n{{end}}")
		env.AfterChange(NoDiagnostics(ForFile("hello.tmpl")))
	})
}

func TestTemplatesObserveDirectoryFilters(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.tmpl --
A {{}} <-- missing body
-- b/b.tmpl --
B {{}} <-- missing body
`

	WithOptions(
		Settings{
			"directoryFilters":   []string{"-b"},
			"templateExtensions": []string{"tmpl"},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.tmpl", "()A")),
			NoDiagnostics(ForFile("b/b.tmpl")),
		)
	})
}

func TestTemplatesFromLangID(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.CreateBuffer("hello.tmpl", "")
		env.AfterChange(
			NoDiagnostics(ForFile("hello.tmpl")), // Don't get spurious errors for empty templates.
		)
		env.SetBufferContent("hello.tmpl", "{{range .Planets}}\nHello {{}}\n{{end}}")
		env.Await(Diagnostics(env.AtRegexp("hello.tmpl", "()Hello {{}}")))
		env.RegexpReplace("hello.tmpl", "{{}}", "{{.}}")
		env.Await(NoDiagnostics(ForFile("hello.tmpl")))
	})
}

func TestClosingTemplatesMakesDiagnosticsDisappear(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- hello.tmpl --
{{range .Planets}}
Hello {{}} <-- missing body
{{end}}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("hello.tmpl")
		env.AfterChange(
			Diagnostics(env.AtRegexp("hello.tmpl", "()Hello {{}}")),
		)
		// Since we don't have templateExtensions configured, closing hello.tmpl
		// should make its diagnostics disappear.
		env.CloseBuffer("hello.tmpl")
		env.AfterChange(
			NoDiagnostics(ForFile("hello.tmpl")),
		)
	})
}

func TestMultipleSuffixes(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- b.gotmpl --
{{define "A"}}goo{{end}}
-- a.tmpl --
{{template "A"}}
`

	WithOptions(
		Settings{
			"templateExtensions": []string{"tmpl", "gotmpl"},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.tmpl")
		x := env.RegexpSearch("a.tmpl", `()A`)
		loc := env.FirstDefinition(x)
		env.OpenFile(env.Sandbox.Workdir.URIToPath(loc.URI))
		refs := env.References(loc)
		if len(refs) != 2 {
			t.Fatalf("got %v reference(s), want 2", len(refs))
		}
		// make sure we got one from b.gotmpl
		want := env.Sandbox.Workdir.URI("b.gotmpl")
		if refs[0].URI != want && refs[1].URI != want {
			t.Errorf("failed to find reference to %s", shorten(want))
			for i, r := range refs {
				t.Logf("%d: URI:%s %v", i, shorten(r.URI), r.Range)
			}
		}

		content, nloc := env.Hover(loc)
		if loc != nloc {
			t.Errorf("loc? got %v, wanted %v", nloc, loc)
		}
		if content.Value != "template A defined" {
			t.Errorf("got %s, wanted 'template A defined", content.Value)
		}
	})
}

// shorten long URIs
func shorten(fn protocol.DocumentURI) string {
	if len(fn) <= 20 {
		return string(fn)
	}
	pieces := strings.Split(string(fn), "/")
	if len(pieces) < 2 {
		return string(fn)
	}
	j := len(pieces)
	return pieces[j-2] + "/" + pieces[j-1]
}

func TestCompletionPanic_Issue57621(t *testing.T) {
	const src = `
-- go.mod --
module mod.com

go 1.12
-- hello.tmpl --
{{range .Planets}}
Hello {{
{{end}}
`
	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("hello.tmpl")
		// None of these should panic.
		env.Completion(env.RegexpSearch("hello.tmpl", `Hello ()\{\{`))
		env.Completion(env.RegexpSearch("hello.tmpl", `Hello \{()\{`))
		env.Completion(env.RegexpSearch("hello.tmpl", `Hello \{\{()`))
		env.Completion(env.RegexpSearch("hello.tmpl", `()\{\{range`))
		env.Completion(env.RegexpSearch("hello.tmpl", `\{()\{range`))
		env.Completion(env.RegexpSearch("hello.tmpl", `\{\{()range`))
		env.Completion(env.RegexpSearch("hello.tmpl", `Planets()}}`))
		env.Completion(env.RegexpSearch("hello.tmpl", `Planets}()}`))
		env.Completion(env.RegexpSearch("hello.tmpl", `Planets}}()`))
	})
}

// Hover needs tests


================================================
FILE: gopls/internal/test/integration/watch/setting_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package watch

import (
	"fmt"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestSubdirWatchPatterns(t *testing.T) {
	const files = `
-- go.mod --
module mod.test

go 1.18
-- subdir/subdir.go --
package subdir
`

	tests := []struct {
		clientName          string
		subdirWatchPatterns string
		wantWatched         bool
	}{
		{"other client", "on", true},
		{"other client", "off", false},
		{"other client", "auto", false},
		{"Visual Studio Code", "auto", true},
	}

	for _, test := range tests {
		t.Run(fmt.Sprintf("%s_%s", test.clientName, test.subdirWatchPatterns), func(t *testing.T) {
			WithOptions(
				ClientName(test.clientName),
				Settings{
					"subdirWatchPatterns": test.subdirWatchPatterns,
				},
			).Run(t, files, func(t *testing.T, env *Env) {
				var expectation Expectation
				if test.wantWatched {
					expectation = FileWatchMatching("subdir")
				} else {
					expectation = NoFileWatchMatching("subdir")
				}
				env.OnceMet(
					InitialWorkspaceLoad,
					expectation,
				)
			})
		})
	}
}

// This test checks that we surface errors for invalid subdir watch patterns,
// as the triple of ("off"|"on"|"auto") may be confusing to users inclined to
// use (true|false) or some other truthy value.
func TestSubdirWatchPatterns_BadValues(t *testing.T) {
	tests := []struct {
		badValue    any
		wantMessage string
	}{
		{true, "invalid type bool (want string)"},
		{false, "invalid type bool (want string)"},
		{"yes", `invalid option "yes"`},
	}

	for _, test := range tests {
		t.Run(fmt.Sprint(test.badValue), func(t *testing.T) {
			WithOptions(
				Settings{
					"subdirWatchPatterns": test.badValue,
				},
			).Run(t, "", func(t *testing.T, env *Env) {
				env.OnceMet(
					InitialWorkspaceLoad,
					ShownMessage(test.wantMessage),
				)
			})
		})
	}
}


================================================
FILE: gopls/internal/test/integration/watch/watch_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package watch

import (
	"os"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

func TestEditFile(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- a/a.go --
package a

func _() {
	var x int
}
`
	// Edit the file when it's *not open* in the workspace, and check that
	// diagnostics are updated.
	t.Run("unopened", func(t *testing.T) {
		Run(t, pkg, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				Diagnostics(env.AtRegexp("a/a.go", "x")),
			)
			env.WriteWorkspaceFile("a/a.go", `package a; func _() {};`)
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
			)
		})
	})

	// Edit the file when it *is open* in the workspace, and check that
	// diagnostics are *not* updated.
	t.Run("opened", func(t *testing.T) {
		Run(t, pkg, func(t *testing.T, env *Env) {
			env.OpenFile("a/a.go")
			// Insert a trivial edit so that we don't automatically update the buffer
			// (see CL 267577).
			env.EditBuffer("a/a.go", fake.NewEdit(0, 0, 0, 0, " "))
			env.AfterChange()
			env.WriteWorkspaceFile("a/a.go", `package a; func _() {};`)
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/a.go", "x")),
			)
		})
	})
}

// Edit a dependency on disk and expect a new diagnostic.
func TestEditDependency(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- b/b.go --
package b

func B() int { return 0 }
-- a/a.go --
package a

import (
	"mod.com/b"
)

func _() {
	_ = b.B()
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange()
		env.WriteWorkspaceFile("b/b.go", `package b; func B() {};`)
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "b.B")),
		)
	})
}

// Edit both the current file and one of its dependencies on disk and
// expect diagnostic changes.
func TestEditFileAndDependency(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- b/b.go --
package b

func B() int { return 0 }
-- a/a.go --
package a

import (
	"mod.com/b"
)

func _() {
	var x int
	_ = b.B()
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.go", "x")),
		)
		env.WriteWorkspaceFiles(map[string]string{
			"b/b.go": `package b; func B() {};`,
			"a/a.go": `package a

import "mod.com/b"

func _() {
	b.B()
}`,
		})
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
			NoDiagnostics(ForFile("b/b.go")),
		)
	})
}

// Delete a dependency and expect a new diagnostic.
func TestDeleteDependency(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- b/b.go --
package b

func B() int { return 0 }
-- a/a.go --
package a

import (
	"mod.com/b"
)

func _() {
	_ = b.B()
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange()
		env.RemoveWorkspaceFile("b/b.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "\"mod.com/b\"")),
		)
	})
}

// Create a dependency on disk and expect the diagnostic to go away.
func TestCreateDependency(t *testing.T) {
	const missing = `
-- go.mod --
module mod.com

go 1.14
-- b/b.go --
package b

func B() int { return 0 }
-- a/a.go --
package a

import (
	"mod.com/c"
)

func _() {
	c.C()
}
`
	Run(t, missing, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.go", "\"mod.com/c\"")),
		)
		env.WriteWorkspaceFile("c/c.go", `package c; func C() {};`)
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
	})
}

// Create a new dependency and add it to the file on disk.
// This is similar to what might happen if you switch branches.
func TestCreateAndAddDependency(t *testing.T) {
	const original = `
-- go.mod --
module mod.com

go 1.14
-- a/a.go --
package a

func _() {}
`
	Run(t, original, func(t *testing.T, env *Env) {
		env.WriteWorkspaceFile("c/c.go", `package c; func C() {};`)
		env.WriteWorkspaceFile("a/a.go", `package a; import "mod.com/c"; func _() { c.C() }`)
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
	})
}

// Create a new file that defines a new symbol, in the same package.
func TestCreateFile(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- a/a.go --
package a

func _() {
	hello()
}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.go", "hello")),
		)
		env.WriteWorkspaceFile("a/a2.go", `package a; func hello() {};`)
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
		)
	})
}

// Add a new method to an interface and implement it.
// Inspired by the structure of internal/golang and internal/cache.
func TestCreateImplementation(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- b/b.go --
package b

type B interface{
	Hello() string
}

func SayHello(bee B) {
	println(bee.Hello())
}
-- a/a.go --
package a

import "mod.com/b"

type X struct {}

func (_ X) Hello() string {
	return ""
}

func _() {
	x := X{}
	b.SayHello(x)
}
`
	const newMethod = `package b
type B interface{
	Hello() string
	Bye() string
}

func SayHello(bee B) {
	println(bee.Hello())
}`
	const implementation = `package a

import "mod.com/b"

type X struct {}

func (_ X) Hello() string {
	return ""
}

func (_ X) Bye() string {
	return ""
}

func _() {
	x := X{}
	b.SayHello(x)
}`

	// Add the new method before the implementation. Expect diagnostics.
	t.Run("method before implementation", func(t *testing.T) {
		Run(t, pkg, func(t *testing.T, env *Env) {
			env.WriteWorkspaceFile("b/b.go", newMethod)
			env.AfterChange(
				Diagnostics(AtPosition("a/a.go", 12, 12)),
			)
			env.WriteWorkspaceFile("a/a.go", implementation)
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
			)
		})
	})
	// Add the new implementation before the new method. Expect no diagnostics.
	t.Run("implementation before method", func(t *testing.T) {
		Run(t, pkg, func(t *testing.T, env *Env) {
			env.WriteWorkspaceFile("a/a.go", implementation)
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
			)
			env.WriteWorkspaceFile("b/b.go", newMethod)
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
			)
		})
	})
	// Add both simultaneously. Expect no diagnostics.
	t.Run("implementation and method simultaneously", func(t *testing.T) {
		Run(t, pkg, func(t *testing.T, env *Env) {
			env.WriteWorkspaceFiles(map[string]string{
				"a/a.go": implementation,
				"b/b.go": newMethod,
			})
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
				NoDiagnostics(ForFile("b/b.go")),
			)
		})
	})
}

// Tests golang/go#38498. Delete a file and then force a reload.
// Assert that we no longer try to load the file.
func TestDeleteFiles(t *testing.T) {
	// TODO(rfindley): this test is brittle, because it depends on underspecified
	// logging behavior around loads.
	//
	// We should have a robust way to test loads. It should be possible to assert
	// on the specific loads that have occurred, and without the synchronization
	// problems associated with logging.

	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- a/a.go --
package a

func _() {
	var _ int
}
-- a/a_unneeded.go --
package a
`
	t.Run("close then delete", func(t *testing.T) {
		WithOptions(
			// verboseOutput causes Snapshot.load to log package files.
			// (see the TODO above: this is brittle)
			Settings{"verboseOutput": true},
		).Run(t, pkg, func(t *testing.T, env *Env) {
			env.OpenFile("a/a.go")
			env.OpenFile("a/a_unneeded.go")
			env.Await(
				// Log messages are asynchronous to other events on the LSP stream, so we
				// can't use OnceMet or AfterChange here.
				LogMatching(protocol.Info, "a_unneeded.go", 1, false),
			)

			// Close and delete the open file, mimicking what an editor would do.
			env.CloseBuffer("a/a_unneeded.go")
			env.RemoveWorkspaceFile("a/a_unneeded.go")
			env.RegexpReplace("a/a.go", "var _ int", "fmt.Println(\"\")")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/a.go", "fmt")),
			)
			env.SaveBuffer("a/a.go")
			env.Await(
				// There should only be one log message containing
				// a_unneeded.go, from the initial workspace load, which we
				// check for earlier. If there are more, there's a bug.
				LogMatching(protocol.Info, "a_unneeded.go", 1, false),
				NoDiagnostics(ForFile("a/a.go")),
			)
		})
	})

	t.Run("delete then close", func(t *testing.T) {
		WithOptions(
			Settings{"verboseOutput": true},
		).Run(t, pkg, func(t *testing.T, env *Env) {
			env.OpenFile("a/a.go")
			env.OpenFile("a/a_unneeded.go")
			env.Await(
				LogMatching(protocol.Info, "a_unneeded.go", 1, false),
			)

			// Delete and then close the file.
			env.RemoveWorkspaceFile("a/a_unneeded.go")
			env.CloseBuffer("a/a_unneeded.go")
			env.RegexpReplace("a/a.go", "var _ int", "fmt.Println(\"\")")
			env.AfterChange(
				Diagnostics(env.AtRegexp("a/a.go", "fmt")),
			)
			env.SaveBuffer("a/a.go")
			env.Await(
				// There should only be one log message containing
				// a_unneeded.go, from the initial workspace load, which we
				// check for earlier. If there are more, there's a bug.
				LogMatching(protocol.Info, "a_unneeded.go", 1, false),
				NoDiagnostics(ForFile("a/a.go")),
			)
		})
	})
}

// This change reproduces the behavior of switching branches, with multiple
// files being created and deleted. The key change here is the movement of a
// symbol from one file to another in a given package through a deletion and
// creation. To reproduce an issue with metadata invalidation in batched
// changes, the last change in the batch is an on-disk file change that doesn't
// require metadata invalidation.
func TestMoveSymbol(t *testing.T) {
	const pkg = `
-- go.mod --
module mod.com

go 1.14
-- main.go --
package main

import "mod.com/a"

func main() {
	var x int
	x = a.Hello
	println(x)
}
-- a/a1.go --
package a

var Hello int
-- a/a2.go --
package a

func _() {}
`
	Run(t, pkg, func(t *testing.T, env *Env) {
		env.WriteWorkspaceFile("a/a3.go", "package a\n\nvar Hello int\n")
		env.RemoveWorkspaceFile("a/a1.go")
		env.WriteWorkspaceFile("a/a2.go", "package a; func _() {};")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// Reproduce golang/go#40456.
func TestChangeVersion(t *testing.T) {
	const proxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

const Name = "Blah"

func X(x int) {}
-- example.com@v1.2.2/go.mod --
module example.com

go 1.12
-- example.com@v1.2.2/blah/blah.go --
package blah

const Name = "Blah"

func X() {}
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/blah/blah.go --
package hello

const Name = "Hello"
`
	const mod = `
-- go.mod --
module mod.com

go 1.12

require example.com v1.2.2
-- main.go --
package main

import "example.com/blah"

func main() {
	blah.X()
}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy)).Run(t, mod, func(t *testing.T, env *Env) {
		env.WriteWorkspaceFiles(map[string]string{
			"go.mod": `module mod.com

go 1.12

require example.com v1.2.3
`,
			"main.go": `package main

import (
	"example.com/blah"
)

func main() {
	blah.X(1)
}
`,
		})
		env.AfterChange(
			env.DoneWithChangeWatchedFiles(),
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// Reproduces golang/go#40340.
func TestSwitchFromGOPATHToModuleMode(t *testing.T) {
	const files = `
-- foo/blah/blah.go --
package blah

const Name = ""
-- main.go --
package main

import "foo/blah"

func main() {
	_ = blah.Name
}
`
	WithOptions(
		InGOPATH(),
		Modes(Default), // golang/go#57521: this test is temporarily failing in 'experimental' mode
		EnvVars{"GO111MODULE": "auto"},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
		if _, err := env.Sandbox.RunGoCommand(env.Ctx, "", "mod", []string{"init", "mod.com"}, nil, true); err != nil {
			t.Fatal(err)
		}

		// TODO(golang/go#57558, golang/go#57512): file watching is asynchronous,
		// and we must wait for the view to be reconstructed before touching
		// main.go, so that the new view "knows" about main.go. This is a bug, but
		// awaiting the change here avoids it.
		env.AfterChange()

		env.RegexpReplace("main.go", `"foo/blah"`, `"mod.com/foo/blah"`)
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
		)
	})
}

// Reproduces golang/go#40487.
func TestSwitchFromModulesToGOPATH(t *testing.T) {
	const files = `
-- foo/go.mod --
module mod.com

go 1.14
-- foo/blah/blah.go --
package blah

const Name = ""
-- foo/main.go --
package main

import "mod.com/blah"

func main() {
	_ = blah.Name
}
`
	WithOptions(
		InGOPATH(),
		EnvVars{"GO111MODULE": "auto"},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/main.go")
		env.RemoveWorkspaceFile("foo/go.mod")
		env.AfterChange(
			Diagnostics(env.AtRegexp("foo/main.go", `"mod.com/blah"`)),
		)
		env.RegexpReplace("foo/main.go", `"mod.com/blah"`, `"foo/blah"`)
		env.AfterChange(
			NoDiagnostics(ForFile("foo/main.go")),
		)
	})
}

func TestNewSymbolInTestVariant(t *testing.T) {
	const files = `
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

func bob() {}
-- a/a_test.go --
package a

import "testing"

func TestBob(t *testing.T) {
	bob()
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		// Add a new symbol to the package under test and use it in the test
		// variant. Expect no diagnostics.
		env.WriteWorkspaceFiles(map[string]string{
			"a/a.go": `package a

func bob() {}
func george() {}
`,
			"a/a_test.go": `package a

import "testing"

func TestAll(t *testing.T) {
	bob()
	george()
}
`,
		})
		env.AfterChange(
			NoDiagnostics(ForFile("a/a.go")),
			NoDiagnostics(ForFile("a/a_test.go")),
		)
		// Now, add a new file to the test variant and use its symbol in the
		// original test file. Expect no diagnostics.
		env.WriteWorkspaceFiles(map[string]string{
			"a/a_test.go": `package a

import "testing"

func TestAll(t *testing.T) {
	bob()
	george()
	hi()
}
`,
			"a/a2_test.go": `package a

import "testing"

func hi() {}

func TestSomething(t *testing.T) {}
`,
		})
		env.AfterChange(
			NoDiagnostics(ForFile("a/a_test.go")),
			NoDiagnostics(ForFile("a/a2_test.go")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/web/assembly_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

import (
	"regexp"
	"runtime"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/internal/testenv"
)

// TestAssembly is a basic test of the web-based assembly listing.
func TestAssembly(t *testing.T) {
	testenv.NeedsGoCommand1Point(t, 22) // for up-to-date assembly listing

	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

func f(x int) int {
	println("hello")
	defer println("world")
	return x
}

func g() {
	println("goodbye")
}

var v = [...]int{
	f(123),
	f(456),
}

func init() {
	f(789)
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		// Get the report and do some minimal checks for sensible results.
		//
		// Use only portable instructions below! Remember that
		// this is a test of plumbing, not compilation, so
		// it's better to skip the tests, rather than refine
		// them, on any architecture that gives us trouble
		// (e.g. uses JAL for CALL, or BL<cc> for RET).
		// We conservatively test only on the two most popular
		// architectures.
		{
			loc := env.RegexpSearch("a/a.go", "println")
			report := asmFor(t, env, loc)
			checkMatch(t, true, report, `TEXT.*example.com/a.f`)
			switch runtime.GOARCH {
			case "amd64", "arm64":
				checkMatch(t, true, report, `CALL	runtime.printlock`)
				checkMatch(t, true, report, `CALL	runtime.printstring`)
				checkMatch(t, true, report, `CALL	runtime.printunlock`)
				checkMatch(t, true, report, `CALL	example.com/a.f.deferwrap`)
				checkMatch(t, true, report, `RET`)
				checkMatch(t, true, report, `CALL	runtime.morestack_noctxt`)
			}

			// Nested functions are also shown.
			//
			// The condition here was relaxed to unblock go.dev/cl/639515.
			checkMatch(t, true, report, `example.com/a.f.deferwrap`)

			// But other functions are not.
			checkMatch(t, false, report, `TEXT.*example.com/a.g`)
		}

		// Check that code in a package-level var initializer is found too.
		{
			loc := env.RegexpSearch("a/a.go", `f\(123\)`)
			report := asmFor(t, env, loc)
			switch runtime.GOARCH {
			case "amd64", "arm64":
				checkMatch(t, true, report, `TEXT.*example.com/a.init`)
				checkMatch(t, true, report, `MOV.?	\$123`)
				checkMatch(t, true, report, `MOV.?	\$456`)
				checkMatch(t, true, report, `CALL	example.com/a.f`)
			}
		}

		// And code in a source-level init function.
		{
			loc := env.RegexpSearch("a/a.go", `f\(789\)`)
			report := asmFor(t, env, loc)
			switch runtime.GOARCH {
			case "amd64", "arm64":
				checkMatch(t, true, report, `TEXT.*example.com/a.init`)
				checkMatch(t, true, report, `MOV.?	\$789`)
				checkMatch(t, true, report, `CALL	example.com/a.f`)
			}
		}
	})
}

// TestTestAssembly exercises assembly listing of tests.
func TestTestAssembly(t *testing.T) {
	testenv.NeedsGoCommand1Point(t, 22) // for up-to-date assembly listing

	const files = `
-- go.mod --
module example.com

-- a/a_test.go --
package a

import "testing"

func Test1(*testing.T) { println(0) }

-- a/a_x_test.go --
package a_test

import "testing"

func Test2(*testing.T) { println(0) }
`
	Run(t, files, func(t *testing.T, env *Env) {
		for _, test := range []struct {
			filename, symbol string
		}{
			{"a/a_test.go", "example.com/a.Test1"},
			{"a/a_x_test.go", "example.com/a_test.Test2"},
		} {
			env.OpenFile(test.filename)
			loc := env.RegexpSearch(test.filename, `println`)
			report := asmFor(t, env, loc)
			checkMatch(t, true, report, `TEXT.*`+regexp.QuoteMeta(test.symbol))
			switch runtime.GOARCH {
			case "amd64", "arm64":
				checkMatch(t, true, report, `CALL	runtime.printint`)
			}
		}
	})
}

// asmFor returns the HTML document served by gopls for a "Browse assembly"
// command at the specified location in an open file.
func asmFor(t *testing.T, env *Env, loc protocol.Location) []byte {
	_, content := codeActionWebPage(t, env, settings.GoAssembly, loc)
	return content
}


================================================
FILE: gopls/internal/test/integration/web/flight_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

import (
	"encoding/json"
	"runtime"
	"testing"

	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestFlightRecorder checks that the flight recorder is minimally functional.
func TestFlightRecorder(t *testing.T) {
	// The usual UNIX mechanisms cause timely termination of the
	// cmd/trace process, but this doesn't happen on Windows,
	// leading to CI failures because of process->file locking.
	// Rather than invent a complex mechanism, skip the test:
	// this feature is only for gopls developers anyway.
	// Better long term solutions are CL 677262 and issue #66843.
	if runtime.GOOS == "windows" {
		t.Skip("not reliable on windows")
	}

	// This is a global hammer; it won't play nicely with
	// multiple concurrent tests of Flight Recorder.
	t.Cleanup(debug.KillTraceViewers)

	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

const A = 1
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		// Start the debug server.
		var result command.DebuggingResult
		env.ExecuteCommand(&protocol.ExecuteCommandParams{
			Command:   command.StartDebugging.String(),
			Arguments: []json.RawMessage{json.RawMessage("{}")}, // no args -> pick port
		}, &result)
		uri := result.URLs[0]
		t.Logf("StartDebugging: URLs[0] = %s", uri)

		// Check the debug server page is sensible.
		doc1 := get(t, uri)
		checkMatch(t, true, doc1, "Gopls server information")
		checkMatch(t, true, doc1, `<a href="/flightrecorder">Flight recorder</a>`)

		// "Click" the Flight Recorder link.
		// It should redirect to the web server
		// of a "go tool trace" process.
		// The resulting web page is entirely programmatic,
		// so we check for an arbitrary expected symbol.
		doc2 := get(t, uri+"/flightrecorder")
		checkMatch(t, true, doc2, `onTraceViewerImportFail`)
	})
}


================================================
FILE: gopls/internal/test/integration/web/freesymbols_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestFreeSymbols is a basic test of interaction with the "free symbols" web report.
func TestFreeSymbols(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

import "fmt"
import "bytes"

func f(buf bytes.Buffer, greeting string) {
/* « */
	fmt.Fprintf(&buf, "%s", greeting)
	buf.WriteString(fmt.Sprint("foo"))
	buf.WriteByte(0)
/* » */
	buf.Write(nil)
}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		// Invoke the "Browse free symbols" code
		// action to start the server.
		loc := env.RegexpSearch("a/a.go", "«((?:.|\n)*)»")
		actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
		if err != nil {
			t.Fatalf("CodeAction: %v", err)
		}
		action, err := CodeActionByKind(actions, settings.GoFreeSymbols)
		if err != nil {
			t.Fatal(err)
		}

		// Execute the command.
		// Its side effect should be a single showDocument request.
		params := &protocol.ExecuteCommandParams{
			Command:   action.Command.Command,
			Arguments: action.Command.Arguments,
		}
		var result command.DebuggingResult
		collectDocs := env.Awaiter.ListenToShownDocuments()
		env.ExecuteCommand(params, &result)
		doc := shownDocument(t, collectDocs(), "http:")
		if doc == nil {
			t.Fatalf("no showDocument call had 'file:' prefix")
		}
		t.Log("showDocument(package doc) URL:", doc.URI)

		// Get the report and do some minimal checks for sensible results.
		report := get(t, doc.URI)
		checkMatch(t, true, report, `<li>import "<a .*'>fmt</a>" // for Fprintf, Sprint</li>`)
		checkMatch(t, true, report, `<li>var <a .*>buf</a>  bytes.Buffer</li>`)
		checkMatch(t, true, report, `<li>func <a .*>WriteByte</a>  func\(c byte\) error</li>`)
		checkMatch(t, true, report, `<li>func <a .*>WriteString</a>  func\(s string\) \(n int, err error\)</li>`)
		checkMatch(t, false, report, `<li>func <a .*>Write</a>`) // not in selection
		checkMatch(t, true, report, `<li>var <a .*>greeting</a>  string</li>`)
	})
}


================================================
FILE: gopls/internal/test/integration/web/pkdoc_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

import (
	"fmt"
	"html"
	"regexp"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TODO(adonovan): define marker test verbs for checking package docs.

// TestBrowsePkgDoc provides basic coverage of the "Browse package
// documentation", which creates a web server on demand.
func TestBrowsePkgDoc(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

const A = 1

type G[T any] int
func (G[T]) F(int, int, int, int, int, int, int, ...int) {}

// EOF
`
	Run(t, files, func(t *testing.T, env *Env) {
		// Assert that the HTML page contains the expected const declaration.
		// (We may need to make allowances for HTML markup.)
		env.OpenFile("a/a.go")
		uri1 := viewPkgDoc(t, env, env.Sandbox.Workdir.EntireFile("a/a.go"))
		doc1 := get(t, uri1)
		checkMatch(t, true, doc1, "const A =.*1")

		// Regression test for signature truncation (#67287, #67294).
		checkMatch(t, true, doc1, regexp.QuoteMeta("func (G[T]) F(int, int, int, ...)"))

		// Check that edits to the buffer (even unsaved) are
		// reflected in the HTML document.
		env.RegexpReplace("a/a.go", "// EOF", "func NewFunc() {}")
		env.Await(env.DoneDiagnosingChanges())
		doc2 := get(t, uri1)
		checkMatch(t, true, doc2, "func NewFunc")

		// TODO(adonovan): assert some basic properties of the
		// HTML document using something like
		// golang.org/x/pkgsite/internal/testing/htmlcheck.

		// Grab the URL in the HTML source link for NewFunc.
		// (We don't have a DOM or JS interpreter so we have
		// to know something of the document internals here.)
		rx := regexp.MustCompile(`<h3 id='NewFunc'.*httpGET\("(.*)"\)`)
		srcURL := html.UnescapeString(string(rx.FindSubmatch(doc2)[1]))

		// Fetch the document. Its result isn't important,
		// but it must have the side effect of another showDocument
		// downcall, this time for a "file:" URL, causing the
		// client editor to navigate to the source file.
		t.Log("extracted /src URL", srcURL)
		collectDocs := env.Awaiter.ListenToShownDocuments()
		get(t, srcURL)

		// Check that shown location is that of NewFunc.
		shownSource := shownDocument(t, collectDocs(), "file:")
		gotLoc := protocol.Location{
			URI:   protocol.DocumentURI(shownSource.URI), // fishy conversion
			Range: *shownSource.Selection,
		}
		t.Log("showDocument(source file) URL:", gotLoc)
		wantLoc := env.RegexpSearch("a/a.go", `func ()NewFunc`)
		if gotLoc != wantLoc {
			t.Errorf("got location %v, want %v", gotLoc, wantLoc)
		}
	})
}

func TestShowDocumentUnsupported(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a.go --
package a

const A = 1
`

	for _, supported := range []bool{false, true} {
		t.Run(fmt.Sprintf("supported=%v", supported), func(t *testing.T) {
			opts := []RunOption{Modes(Default)}
			if !supported {
				opts = append(opts, CapabilitiesJSON([]byte(`
{
	"window": {
		"showDocument": {
			"support": false
		}
	}
}`)))
			}
			WithOptions(opts...).Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("a.go")
				// Invoke the "Browse package documentation" code
				// action to start the server.
				actions := env.CodeAction(env.Sandbox.Workdir.EntireFile("a.go"), nil, 0)
				docAction, err := CodeActionByKind(actions, settings.GoDoc)
				if err != nil {
					t.Fatal(err)
				}

				// Execute the command.
				// Its side effect should be a single showDocument request.
				params := &protocol.ExecuteCommandParams{
					Command:   docAction.Command.Command,
					Arguments: docAction.Command.Arguments,
				}
				var result any
				collectDocs := env.Awaiter.ListenToShownDocuments()
				collectMessages := env.Awaiter.ListenToShownMessages()
				env.ExecuteCommand(params, &result)

				// golang/go#70342: just because the command has finished does not mean
				// that we will have received the necessary notifications. Synchronize
				// using progress reports.
				env.Await(CompletedWork(params.Command, 1, false))

				wantDocs, wantMessages := 0, 1
				if supported {
					wantDocs, wantMessages = 1, 0
				}

				docs := collectDocs()
				messages := collectMessages()

				if gotDocs := len(docs); gotDocs != wantDocs {
					t.Errorf("gopls.doc: got %d showDocument requests, want %d", gotDocs, wantDocs)
				}
				if gotMessages := len(messages); gotMessages != wantMessages {
					t.Errorf("gopls.doc: got %d showMessage requests, want %d", gotMessages, wantMessages)
				}
			})
		})
	}
}

func TestPkgDocNoPanic66449(t *testing.T) {
	// This particular input triggered a latent bug in doc.New
	// that would corrupt the AST while filtering out unexported
	// symbols such as b, causing nodeHTML to panic.
	// Now it doesn't crash.
	//
	// We also check cross-reference anchors for all symbols.
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

// The 'π' suffix is to elimimate spurious matches with other HTML substrings,
// in particular the random base64 secret tokens that appear in gopls URLs.

var Vπ, vπ = 0, 0
const Cπ, cπ = 0, 0

func Fπ()
func fπ()

type Tπ int
type tπ int

func (Tπ) Mπ() {}
func (Tπ) mπ() {}

func (tπ) Mπ() {}
func (tπ) mπ() {}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		uri1 := viewPkgDoc(t, env, env.Sandbox.Workdir.EntireFile("a/a.go"))

		doc := get(t, uri1)
		// (Ideally our code rendering would also
		// eliminate unexported symbols...)
		checkMatch(t, true, doc, "var Vπ, vπ = .*0.*0")
		checkMatch(t, true, doc, "const Cπ, cπ = .*0.*0")

		// Unexported funcs/types/... must still be discarded.
		checkMatch(t, true, doc, "Fπ")
		checkMatch(t, false, doc, "fπ")
		checkMatch(t, true, doc, "Tπ")
		checkMatch(t, false, doc, "tπ")

		// Also, check that anchors exist (only) for exported symbols.
		// exported:
		checkMatch(t, true, doc, "<a id='Vπ'")
		checkMatch(t, true, doc, "<a id='Cπ'")
		checkMatch(t, true, doc, "<h3 id='Tπ'")
		checkMatch(t, true, doc, "<h3 id='Fπ'")
		checkMatch(t, true, doc, "<h4 id='Tπ.Mπ'")
		// unexported:
		checkMatch(t, false, doc, "<a id='vπ'")
		checkMatch(t, false, doc, "<a id='cπ'")
		checkMatch(t, false, doc, "<h3 id='tπ'")
		checkMatch(t, false, doc, "<h3 id='fπ'")
		checkMatch(t, false, doc, "<h4 id='Tπ.mπ'")
		checkMatch(t, false, doc, "<h4 id='tπ.Mπ'")
		checkMatch(t, false, doc, "<h4 id='tπ.mπ'")
	})
}

// TestPkgDocNavigation tests that the symbol selector and index of
// symbols are well formed.
func TestPkgDocNavigation(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

func Func1(int, string, bool, []string) (int, error)
func Func2(x, y int, a, b string) (int, error)

type Type struct {}
func (t Type) Method() {}
func (p *Type) PtrMethod() {}

func Constructor() Type
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		uri1 := viewPkgDoc(t, env, env.Sandbox.Workdir.EntireFile("a/a.go"))
		doc := get(t, uri1)

		q := regexp.QuoteMeta

		// selector
		checkMatch(t, true, doc, q(`<option label='Func1(_, _, _, _)' value='#Func1'/>`))
		checkMatch(t, true, doc, q(`<option label='Func2(x, y, a, b)' value='#Func2'/>`))
		checkMatch(t, true, doc, q(`<option label='Type' value='#Type'/>`))
		checkMatch(t, true, doc, q(`<option label='Constructor()' value='#Constructor'/>`))
		checkMatch(t, true, doc, q(`<option label='(t) Method()' value='#Type.Method'/>`))
		checkMatch(t, true, doc, q(`<option label='(p) PtrMethod()' value='#Type.PtrMethod'/>`))

		// index
		checkMatch(t, true, doc, q(`<li><a href='#Func1'>func Func1(int, string, bool, ...) (int, error)</a></li>`))
		checkMatch(t, true, doc, q(`<li><a href='#Func2'>func Func2(x int, y int, a string, ...) (int, error)</a></li>`))
		checkMatch(t, true, doc, q(`<li><a href='#Type'>type Type</a></li>`))
		checkMatch(t, true, doc, q(`<li><a href='#Constructor'>func Constructor() Type</a></li>`))
		checkMatch(t, true, doc, q(`<li><a href='#Type.Method'>func (t Type) Method()</a></li>`))
		checkMatch(t, true, doc, q(`<li><a href='#Type.PtrMethod'>func (p *Type) PtrMethod()</a></li>`))
	})
}

// TestPkgDocContext tests that the gopls.doc command title and /pkg
// URL are appropriate for the current selection. It is effectively a
// test of golang.DocFragment.
func TestPkgDocContext(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

import "fmt"
import "bytes"

func A() {
	fmt.Println()
	new(bytes.Buffer).Write(nil)
}

const K = 123

type T int
func (*T) M() { /*in T.M*/}

`

	viewRE := regexp.MustCompile("view=[0-9]*")
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		for _, test := range []struct {
			re   string // regexp indicating selected portion of input file
			want string // suffix of expected URL after /pkg/
		}{
			// current package
			{"package a", "example.com/a?view=1"},  // outside any decl
			{"in T.M", "example.com/a?view=1#T.M"}, // inside method (*T).M
			{"123", "example.com/a?view=1#K"},      // inside const/var decl
			{"T int", "example.com/a?view=1#T"},    // inside type decl

			// imported
			{"\"fmt\"", "fmt?view=1"},              // in import spec
			{"fmt()[.]", "fmt?view=1"},             // use of PkgName
			{"Println", "fmt?view=1#Println"},      // use of imported pkg-level symbol
			{"fmt.Println", "fmt?view=1#Println"},  // qualified identifier
			{"Write", "bytes?view=1#Buffer.Write"}, // use of imported method

			// TODO(adonovan):
			// - xtest package -> ForTest
			// - field of imported struct -> nope
			// - exported method of nonexported type from another package
			//   (e.g. types.Named.Obj) -> nope
			// Also: assert that Command.Title looks nice.
		} {
			uri := viewPkgDoc(t, env, env.RegexpSearch("a/a.go", test.re))
			_, got, ok := strings.Cut(uri, "/pkg/")
			if !ok {
				t.Errorf("pattern %q => %s (invalid /pkg URL)", test.re, uri)
				continue
			}

			// Normalize the view ID, which varies by integration test mode.
			got = viewRE.ReplaceAllString(got, "view=1")

			if got != test.want {
				t.Errorf("pattern %q => %s; want %s", test.re, got, test.want)
			}
		}
	})
}

// TestPkgDocFileImports tests that the doc links are rendered
// as URLs based on the correct import mapping for the file in
// which they appear.
func TestPkgDocFileImports(t *testing.T) {
	const files = `
-- go.mod --
module mod.com
go 1.20

-- a/a1.go --
// Package a refers to [b.T] [b.U] [alias.D] [d.D] [c.T] [c.U] [nope.Nope]
package a

import "mod.com/b"
import alias "mod.com/d"

// [b.T] indeed refers to b.T.
//
// [alias.D] refers to d.D
// but [d.D] also refers to d.D.
type A1 int

-- a/a2.go --
package a

import b "mod.com/c"

// [b.U] actually refers to c.U.
type A2 int

-- b/b.go --
package b

type T int
type U int

-- c/c.go --
package c

type T int
type U int

-- d/d.go --
package d

type D int
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a1.go")
		uri1 := viewPkgDoc(t, env, env.Sandbox.Workdir.EntireFile("a/a1.go"))
		doc := get(t, uri1)

		// Check that the doc links are resolved using the
		// appropriate import mapping for the file in which
		// they appear.
		checkMatch(t, true, doc, `pkg/mod.com/b\?.*#T">b.T</a> indeed refers to b.T`)
		checkMatch(t, true, doc, `pkg/mod.com/c\?.*#U">b.U</a> actually refers to c.U`)

		// Check that doc links can be resolved using either
		// the original or the local name when they refer to a
		// renaming import. (Local names are preferred.)
		checkMatch(t, true, doc, `pkg/mod.com/d\?.*#D">alias.D</a> refers to d.D`)
		checkMatch(t, true, doc, `pkg/mod.com/d\?.*#D">d.D</a> also refers to d.D`)

		// Check that links in the package doc comment are
		// resolved, and relative to the correct file (a1.go).
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/b\?.*#T">b.T</a>`)
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/b\?.*#U">b.U</a>`)
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/d\?.*#D">alias.D</a>`)
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/d\?.*#D">d.D</a>`)
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/c\?.*#T">c.T</a>`)
		checkMatch(t, true, doc, `Package a refers to.*pkg/mod.com/c\?.*#U">c.U</a>`)
		checkMatch(t, true, doc, `Package a refers to.* \[nope.Nope\]`)
	})
}

// TestPkgDocConstructorOfUnexported tests that exported constructor
// functions (NewT) whose result type (t) is unexported are not
// discarded but are presented as ordinary top-level functions (#69553).
func TestPkgDocConstructorOfUnexported(t *testing.T) {
	const files = `
-- go.mod --
module mod.com
go 1.20

-- a/a.go --
package a

func A() {}
func Z() {}

type unexported int
func NewUnexported() unexported // exported constructor of unexported type

type Exported int
func NewExported() Exported // exported constructor of exported type
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		uri1 := viewPkgDoc(t, env, env.Sandbox.Workdir.EntireFile("a/a.go"))
		doc := get(t, uri1)

		want := regexp.QuoteMeta(`
<optgroup label='Functions'>
  <option label='A()' value='#A'/>
  <option label='NewUnexported()' value='#NewUnexported'/>
  <option label='Z()' value='#Z'/>
</optgroup>
<optgroup label='Types'>
  <option label='Exported' value='#Exported'/>
</optgroup>
<optgroup label='type Exported'>
  <option label='NewExported()' value='#NewExported'/>
</optgroup>`)
		checkMatch(t, true, doc, want)
	})
}

// viewPkgDoc invokes the "Browse package documentation" code action
// at the specified location. It returns the URI of the document, or
// fails the test.
func viewPkgDoc(t *testing.T, env *Env, loc protocol.Location) protocol.URI {
	// Invoke the "Browse package documentation" code
	// action to start the server.
	actions := env.CodeAction(loc, nil, 0)
	docAction, err := CodeActionByKind(actions, settings.GoDoc)
	if err != nil {
		t.Fatal(err)
	}

	// Execute the command.
	// Its side effect should be a single showDocument request.
	params := &protocol.ExecuteCommandParams{
		Command:   docAction.Command.Command,
		Arguments: docAction.Command.Arguments,
	}
	var result any
	collectDocs := env.Awaiter.ListenToShownDocuments()
	env.ExecuteCommand(params, &result)

	doc := shownDocument(t, collectDocs(), "http:")
	if doc == nil {
		t.Fatalf("no showDocument call had 'http:' prefix")
	}
	if false {
		t.Log("showDocument(package doc) URL:", doc.URI)
	}
	return doc.URI
}


================================================
FILE: gopls/internal/test/integration/web/splitpkg_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

import (
	"bytes"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"slices"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/golang/splitpkg"
	"golang.org/x/tools/gopls/internal/settings"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestSplitPackage is a basic test of the web-based split package tool.
func TestSplitPackage(t *testing.T) {
	const files = `
-- go.mod --
module example.com

-- a/a.go --
package a

func a() { b1() }

func b1() { b2() }
func b2() { b1(); c() }

// EOF
-- a/b.go --
package a

func c() { d() }

func d() {}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")

		// Get the web page and do some rudimentary checks.
		// Most of the action happens in *.js (which we can't test)
		// and in interaction with the JSON endpoints (which we can).
		loc := env.RegexpSearch("a/a.go", "package")
		uri, page := codeActionWebPage(t, env, settings.GoSplitPackage, loc)

		checkMatch(t, true, page, `<h1>Split package example.com/a</h1>`)

		// Now we interact using JSON, basically a trivial Go
		// version of the splitpkg.js code.

		// jsonHTTP performs a JSON-over-HTTP request to the specified path.
		jsonHTTP := func(method, path string, in, out any) {
			// Replace the /splitpkg portion of the main page's URL,
			// keeping everything else.
			u, err := url.Parse(uri)
			if err != nil {
				t.Fatalf("parsing URL: %v", err)
			}
			u.Path = strings.ReplaceAll(u.Path, "/splitpkg", path)

			// HTTP
			inJSON, err := json.Marshal(in)
			if err != nil {
				t.Fatalf("encoding input: %v", err)
			}
			t.Logf("%s: in=%s", path, inJSON)
			req, err := http.NewRequest(method, u.String(), bytes.NewReader(inJSON))
			if err != nil {
				t.Fatalf("NewRequest: %v", err)
			}
			req.Header.Set("Content-Type", "application/json")
			resp, err := http.DefaultClient.Do(req)
			if err != nil {
				t.Fatalf("HTTP request: %v", err)
			}
			defer resp.Body.Close()
			outJSON, err := io.ReadAll(resp.Body)
			if err != nil {
				t.Fatalf("reading output: %v", err)
			}
			t.Logf("%s: out=%s", path, outJSON)
			if out != nil {
				if err := json.Unmarshal(outJSON, out); err != nil {
					t.Fatalf("decoding output: %v", err)
				}
			}
		}

		// checkFileDecls queries the current package's decls grouped by file
		// and asserts that they match the description of the wanted state.
		checkFileDecls := func(want string) {
			var res splitpkg.ResultJSON
			jsonHTTP("GET", "/splitpkg-json", nil, &res)

			var lines []string
			for _, file := range res.Files {
				var buf strings.Builder
				fmt.Fprintf(&buf, "file %s:", file.Base)
				for _, decl := range file.Decls {
					for _, spec := range decl.Specs {
						fmt.Fprintf(&buf, " %s %s;", decl.Kind, spec.Name)
					}
				}
				lines = append(lines, buf.String())
			}
			slices.Sort(lines)
			got := strings.Join(lines, "\n")

			if diff := cmp.Diff(want, got); diff != "" {
				t.Errorf("unexpected file decls:\ngot:\n%s\nwant:\n%s\ndiff:\n%s", got, want, diff)
			}
		}

		// checkEdges queries the current decomposition and asserts
		// that it matches the description of the wanted state.
		checkEdges := func(want string) {
			var res splitpkg.ResultJSON
			jsonHTTP("GET", "/splitpkg-json", nil, &res)

			var lines []string
			for _, edge := range res.Edges {
				var buf strings.Builder
				fmt.Fprintf(&buf, "edge %s -> %s:", res.Components.Names[edge.From], res.Components.Names[edge.To])
				if edge.Cyclic {
					buf.WriteString(" ⚠")
				}
				for _, ref := range edge.Refs {
					fmt.Fprintf(&buf, " %s -> %s;", ref.From, ref.To)
				}
				lines = append(lines, buf.String())
			}
			slices.Sort(lines)
			got := strings.Join(lines, "\n")
			if diff := cmp.Diff(want, got); diff != "" {
				t.Errorf("unexpected component edges:\ngot:\n%s\nwant:\n%s\ndiff:\n%s", got, want, diff)
			}
		}

		// Check the initial file/decl state.
		checkFileDecls(`
file a.go: func a; func b1; func b2;
file b.go: func c; func d;`[1:])

		// Check that the set of decls updates as we edit the files.
		env.RegexpReplace("a/a.go", "// EOF", "func b3() {}")
		env.Await(env.DoneDiagnosingChanges())
		checkFileDecls(`
file a.go: func a; func b1; func b2; func b3;
file b.go: func c; func d;`[1:])

		// Post a cyclic decomposition. Check the report.
		jsonHTTP("POST", "/splitpkg-components", splitpkg.ComponentsJSON{
			Names:       []string{"zero", "one", "two", "three"},
			Assignments: map[string]int{"a": 0, "b1": 1, "b2": 2, "c": 3, "d": 3},
		}, nil)
		checkEdges(`
edge one -> two: ⚠ b1 -> b2;
edge two -> one: ⚠ b2 -> b1;
edge two -> three: b2 -> c;
edge zero -> one: a -> b1;`[1:])

		// Post an acyclic decomposition. Check the report.
		jsonHTTP("POST", "/splitpkg-components", splitpkg.ComponentsJSON{
			Names:       []string{"zero", "one", "two", "three"},
			Assignments: map[string]int{"a": 0, "b1": 1, "b2": 1, "c": 2, "d": 3},
		}, nil)
		checkEdges(`
edge one -> two: b2 -> c;
edge two -> three: c -> d;
edge zero -> one: a -> b1;`[1:])
	})
}


================================================
FILE: gopls/internal/test/integration/web/util_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package web_test

// This file defines web server testing utilities.

import (
	"io"
	"net/http"
	"os"
	"regexp"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/util/bug"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(integration.Main(m))
}

// shownDocument returns the first shown document matching the URI prefix.
// It may be nil.
// As a side effect, it clears the list of accumulated shown documents.
func shownDocument(t *testing.T, shown []*protocol.ShowDocumentParams, prefix string) *protocol.ShowDocumentParams {
	t.Helper()
	var first *protocol.ShowDocumentParams
	for _, sd := range shown {
		if strings.HasPrefix(sd.URI, prefix) {
			if first != nil {
				t.Errorf("got multiple showDocument requests: %#v", shown)
				break
			}
			first = sd
		}
	}
	return first
}

// get fetches the content of a document over HTTP.
func get(t *testing.T, url string) []byte {
	t.Helper()
	resp, err := http.Get(url)
	if err != nil {
		t.Fatal(err)
	}
	defer resp.Body.Close()
	got, err := io.ReadAll(resp.Body)
	if err != nil {
		t.Fatal(err)
	}
	return got
}

// checkMatch asserts that got matches (or doesn't match, if !want) the pattern.
func checkMatch(t *testing.T, want bool, got []byte, pattern string) {
	t.Helper()
	if regexp.MustCompile(pattern).Match(got) != want {
		if want {
			t.Errorf("input did not match wanted pattern %q; got:\n%s", pattern, got)
		} else {
			t.Errorf("input matched unwanted pattern %q; got:\n%s", pattern, got)
		}
	}
}

// codeActionWebPage returns the URL and content of the page opened by the specified code action.
func codeActionWebPage(t *testing.T, env *integration.Env, kind protocol.CodeActionKind, loc protocol.Location) (string, []byte) {
	actions, err := env.Editor.CodeAction(env.Ctx, loc, nil, protocol.CodeActionUnknownTrigger)
	if err != nil {
		t.Fatalf("CodeAction: %v", err)
	}
	action, err := integration.CodeActionByKind(actions, kind)
	if err != nil {
		t.Fatal(err)
	}
	action, err = env.Editor.ResolveCodeAction(env.Ctx, action)
	if err != nil {
		t.Fatal(err)
	}

	// Execute the command.
	// Its side effect should be a single showDocument request.
	params := &protocol.ExecuteCommandParams{
		Command:   action.Command.Command,
		Arguments: action.Command.Arguments,
	}
	var result command.DebuggingResult
	collectDocs := env.Awaiter.ListenToShownDocuments()
	env.ExecuteCommand(params, &result)
	doc := shownDocument(t, collectDocs(), "http:")
	if doc == nil {
		t.Fatalf("no showDocument call had 'file:' prefix")
	}
	t.Log("showDocument(package doc) URL:", doc.URI)

	return doc.URI, get(t, doc.URI)
}


================================================
FILE: gopls/internal/test/integration/workspace/adhoc_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test for golang/go#57209: editing a file in an ad-hoc package should not
// trigger conflicting diagnostics.
func TestAdhoc_Edits(t *testing.T) {
	const files = `
-- a.go --
package foo

const X = 1

-- b.go --
package foo

// import "errors"

const Y = X
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("b.go")

		for range 10 {
			env.RegexpReplace("b.go", `// import "errors"`, `import "errors"`)
			env.RegexpReplace("b.go", `import "errors"`, `// import "errors"`)
			env.AfterChange(NoDiagnostics())
		}
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/broken_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/server"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// This file holds various tests for UX with respect to broken workspaces.
//
// TODO: consolidate other tests here.
//
// TODO: write more tests:
//  - an explicit GOWORK value that doesn't exist
//  - using modules and/or GOWORK inside of GOPATH?

// Test for golang/go#53933
func TestBrokenWorkspace_DuplicateModules(t *testing.T) {
	// This proxy module content is replaced by the workspace, but is still
	// required for module resolution to function in the Go command.
	const proxy = `
-- example.com/foo@v0.0.1/go.mod --
module example.com/foo

go 1.12
`

	const src = `
-- go.work --
go 1.18

use (
	./package1
	./package1/vendor/example.com/foo
	./package2
	./package2/vendor/example.com/foo
)

-- package1/go.mod --
module mod.test

go 1.18

require example.com/foo v0.0.1
-- package1/main.go --
package main

import "example.com/foo"

func main() {
	_ = foo.CompleteMe
}
-- package1/vendor/example.com/foo/go.mod --
module example.com/foo

go 1.18
-- package1/vendor/example.com/foo/foo.go --
package foo

const CompleteMe = 111
-- package2/go.mod --
module mod2.test

go 1.18

require example.com/foo v0.0.1
-- package2/main.go --
package main

import "example.com/foo"

func main() {
	_ = foo.CompleteMe
}
-- package2/vendor/example.com/foo/go.mod --
module example.com/foo

go 1.18
-- package2/vendor/example.com/foo/foo.go --
package foo

const CompleteMe = 222
`

	WithOptions(
		ProxyFiles(proxy),
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("package1/main.go")
		env.AfterChange(
			OutstandingWork(server.WorkspaceLoadFailure, `module example.com/foo appears multiple times in workspace`),
		)

		// Remove the redundant vendored copy of example.com.
		env.WriteWorkspaceFile("go.work", `go 1.18
		use (
			./package1
			./package2
			./package2/vendor/example.com/foo
		)
		`)
		env.AfterChange(NoOutstandingWork(IgnoreTelemetryPromptWork))

		// Check that definitions in package1 go to the copy vendored in package2.
		location := string(env.FirstDefinition(env.RegexpSearch("package1/main.go", "CompleteMe")).URI)
		const wantLocation = "package2/vendor/example.com/foo/foo.go"
		if !strings.HasSuffix(location, wantLocation) {
			t.Errorf("got definition of CompleteMe at %q, want %q", location, wantLocation)
		}
	})
}

// Test for golang/go#43186: correcting the module path should fix errors
// without restarting gopls.
func TestBrokenWorkspace_WrongModulePath(t *testing.T) {
	const files = `
-- go.mod --
module mod.testx

go 1.18
-- p/internal/foo/foo.go --
package foo

const C = 1
-- p/internal/bar/bar.go --
package bar

import "mod.test/p/internal/foo"

const D = foo.C + 1
-- p/internal/bar/bar_test.go --
package bar_test

import (
	"mod.test/p/internal/foo"
	. "mod.test/p/internal/bar"
)

const E = D + foo.C
-- p/internal/baz/baz_test.go --
package baz_test

import (
	named "mod.test/p/internal/bar"
)

const F = named.D - 3
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p/internal/bar/bar.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("p/internal/bar/bar.go", "\"mod.test/p/internal/foo\"")),
		)
		env.OpenFile("go.mod")
		env.RegexpReplace("go.mod", "mod.testx", "mod.test")
		env.SaveBuffer("go.mod") // saving triggers a reload
		env.AfterChange(NoDiagnostics())
	})
}

func TestMultipleModules_Warning(t *testing.T) {
	t.Skip("temporary skip for golang/go#57979: revisit after zero-config logic is in place")

	msgForVersion := func(ver int) string {
		if ver >= 18 {
			return `gopls was not able to find modules in your workspace.`
		} else {
			return `gopls requires a module at the root of your workspace.`
		}
	}

	const modules = `
-- a/go.mod --
module a.com

go 1.12
-- a/a.go --
package a
-- a/empty.go --
// an empty file
-- b/go.mod --
module b.com

go 1.12
-- b/b.go --
package b
`
	for _, go111module := range []string{"on", "auto"} {
		t.Run("GO111MODULE="+go111module, func(t *testing.T) {
			WithOptions(
				Modes(Default),
				EnvVars{"GO111MODULE": go111module},
			).Run(t, modules, func(t *testing.T, env *Env) {
				ver := env.GoVersion()
				msg := msgForVersion(ver)
				env.OpenFile("a/a.go")
				env.OpenFile("a/empty.go")
				env.OpenFile("b/go.mod")
				env.AfterChange(
					Diagnostics(env.AtRegexp("a/a.go", "package a")),
					Diagnostics(env.AtRegexp("b/go.mod", "module b.com")),
					OutstandingWork(server.WorkspaceLoadFailure, msg),
				)

				// Changing the workspace folders to the valid modules should resolve
				// the workspace errors and diagnostics.
				//
				// TODO(rfindley): verbose work tracking doesn't follow changing the
				// workspace folder, therefore we can't invoke AfterChange here.
				env.ChangeWorkspaceFolders("a", "b")
				env.Await(
					NoDiagnostics(ForFile("a/a.go")),
					NoDiagnostics(ForFile("b/go.mod")),
					NoOutstandingWork(IgnoreTelemetryPromptWork),
				)

				env.ChangeWorkspaceFolders(".")

				// TODO(rfindley): when GO111MODULE=auto, we need to open or change a
				// file here in order to detect a critical error. This is because gopls
				// has forgotten about a/a.go, and therefore doesn't hit the heuristic
				// "all packages are command-line-arguments".
				//
				// This is broken, and could be fixed by adjusting the heuristic to
				// account for the scenario where there are *no* workspace packages, or
				// (better) trying to get workspace packages for each open file. See
				// also golang/go#54261.
				env.OpenFile("b/b.go")
				env.AfterChange(
					// TODO(rfindley): fix these missing diagnostics.
					// Diagnostics(env.AtRegexp("a/a.go", "package a")),
					// Diagnostics(env.AtRegexp("b/go.mod", "module b.com")),
					Diagnostics(env.AtRegexp("b/b.go", "package b")),
					OutstandingWork(server.WorkspaceLoadFailure, msg),
				)
			})
		})
	}

	// Expect no warning if GO111MODULE=auto in a directory in GOPATH.
	t.Run("GOPATH_GO111MODULE_auto", func(t *testing.T) {
		WithOptions(
			Modes(Default),
			EnvVars{"GO111MODULE": "auto"},
			InGOPATH(),
		).Run(t, modules, func(t *testing.T, env *Env) {
			env.OpenFile("a/a.go")
			env.AfterChange(
				NoDiagnostics(ForFile("a/a.go")),
				NoOutstandingWork(IgnoreTelemetryPromptWork),
			)
		})
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/didcreatefiles_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"context"
	"fmt"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TestAutoFillPackageDecl tests that creation of a new .go file causes
// gopls to choose a sensible package name and fill in the package declaration.
func TestAutoFillPackageDecl(t *testing.T) {
	const existFiles = `
-- go.mod --
module mod.com

go 1.12

-- dog/a_test.go --
package dog
-- fruits/apple.go --
package apple

fun apple() int {
	return 0
}

-- license/license.go --
/* Copyright 2025 The Go Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file. */

package license

-- license1/license.go --
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package license1

-- cmd/main.go --
package main

-- integration/a_test.go --
package integration_test

-- nopkg/testfile.go --
package
`
	for _, tc := range []struct {
		name    string
		newfile string
		want    string
	}{
		{
			name:    "new file in folder with a_test.go",
			newfile: "dog/newfile.go",
			want:    "package dog\n",
		},
		{
			name:    "new file in folder with go file",
			newfile: "fruits/newfile.go",
			want:    "package apple\n",
		},
		{
			name:    "new test file in folder with go file",
			newfile: "fruits/newfile_test.go",
			want:    "package apple\n",
		},
		{
			name:    "new file in folder with go file that contains license comment",
			newfile: "license/newfile.go",
			want: `/* Copyright 2025 The Go Authors. All rights reserved.
Use of this source code is governed by a BSD-style
license that can be found in the LICENSE file. */

package license
`,
		},
		{
			name:    "new file in folder with go file that contains license comment",
			newfile: "license1/newfile.go",
			want: `// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package license1
`,
		},
		{
			name:    "new file in folder with main package",
			newfile: "cmd/newfile.go",
			want:    "package main\n",
		},
		{
			name:    "new file in empty folder",
			newfile: "empty_folder/newfile.go",
			want:    "package emptyfolder\n",
		},
		{
			name:    "new file in folder with integration_test package",
			newfile: "integration/newfile.go",
			want:    "package integration\n",
		},
		{
			name:    "new test file in folder with integration_test package",
			newfile: "integration/newfile_test.go",
			want:    "package integration\n",
		},
		{
			name:    "new file in folder with incomplete package clause",
			newfile: "incomplete/newfile.go",
			want:    "package incomplete\n",
		},
		{
			name:    "package completion for dir name with punctuation",
			newfile: "123f_r.u~its-123/newfile.go",
			want:    "package fruits123\n",
		},
		{
			name:    "package completion for dir name with invalid dir name",
			newfile: "123f_r.u~its-123/newfile.go",
			want:    "package fruits123\n",
		},
	} {
		t.Run(tc.name, func(t *testing.T) {
			createFiles := fmt.Sprintf("%s\n-- %s --", existFiles, tc.newfile)
			Run(t, createFiles, func(t *testing.T, env *Env) {
				env.DidCreateFiles(env.Editor.DocumentURI(tc.newfile))
				// save buffer to ensure the edits take effects in the file system.
				if err := env.Editor.SaveBuffer(context.Background(), tc.newfile); err != nil {
					t.Fatal(err)
				}
				if got := env.FileContent(tc.newfile); tc.want != got {
					t.Fatalf("want '%s' but got '%s'", tc.want, got)
				}
			})
		})
	}
}


================================================
FILE: gopls/internal/test/integration/workspace/directoryfilters_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"sort"
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// This file contains regression tests for the directoryFilters setting.
//
// TODO:
//  - consolidate some of these tests into a single test
//  - add more tests for changing directory filters

func TestDirectoryFilters(t *testing.T) {
	WithOptions(
		ProxyFiles(workspaceProxy),
		WorkspaceFolders("pkg"),
		Settings{
			"directoryFilters": []string{"-inner"},
		},
	).Run(t, workspaceModule, func(t *testing.T, env *Env) {
		syms := env.Symbol("Hi")
		sort.Slice(syms, func(i, j int) bool { return syms[i].ContainerName < syms[j].ContainerName })
		for _, s := range syms {
			if strings.Contains(s.ContainerName, "inner") {
				t.Errorf("WorkspaceSymbol: found symbol %q with container %q, want \"inner\" excluded", s.Name, s.ContainerName)
			}
		}
	})
}

func TestDirectoryFiltersLoads(t *testing.T) {
	// exclude, and its error, should be excluded from the workspace.
	const files = `
-- go.mod --
module example.com

go 1.12
-- exclude/exclude.go --
package exclude

const _ = Nonexistant
`

	WithOptions(
		Settings{"directoryFilters": []string{"-exclude"}},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			NoDiagnostics(ForFile("exclude/x.go")),
		)
	})
}

func TestDirectoryFiltersTransitiveDep(t *testing.T) {
	// Even though exclude is excluded from the workspace, it should
	// still be importable as a non-workspace package.
	const files = `
-- go.mod --
module example.com

go 1.12
-- include/include.go --
package include
import "example.com/exclude"

const _ = exclude.X
-- exclude/exclude.go --
package exclude

const _ = Nonexistant // should be ignored, since this is a non-workspace package
const X = 1
`

	WithOptions(
		Settings{"directoryFilters": []string{"-exclude"}},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			NoDiagnostics(ForFile("exclude/exclude.go")), // filtered out
			NoDiagnostics(ForFile("include/include.go")), // successfully builds
		)
	})
}

// Test for golang/go#46438: support for '**' in directory filters.
func TestDirectoryFilters_Wildcard(t *testing.T) {
	filters := []string{"-**/bye"}
	WithOptions(
		ProxyFiles(workspaceProxy),
		WorkspaceFolders("pkg"),
		Settings{
			"directoryFilters": filters,
		},
	).Run(t, workspaceModule, func(t *testing.T, env *Env) {
		syms := env.Symbol("Bye")
		sort.Slice(syms, func(i, j int) bool { return syms[i].ContainerName < syms[j].ContainerName })
		for _, s := range syms {
			if strings.Contains(s.ContainerName, "bye") {
				t.Errorf("WorkspaceSymbol: found symbol %q with container %q with filters %v", s.Name, s.ContainerName, filters)
			}
		}
	})
}

// Test for golang/go#52993: wildcard directoryFilters should apply to
// goimports scanning as well.
func TestDirectoryFilters_ImportScanning(t *testing.T) {
	const files = `
-- go.mod --
module mod.test

go 1.12
-- main.go --
package main

func main() {
	bye.Goodbye()
	hi.Hello()
}
-- p/bye/bye.go --
package bye

func Goodbye() {}
-- hi/hi.go --
package hi

func Hello() {}
`

	WithOptions(
		Settings{
			"directoryFilters": []string{"-**/bye", "-hi"},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		beforeSave := env.BufferText("main.go")
		env.OrganizeImports("main.go")
		got := env.BufferText("main.go")
		if got != beforeSave {
			t.Errorf("after organizeImports code action, got modified buffer:\n%s", got)
		}
	})
}

// Test for golang/go#52993: non-wildcard directoryFilters should still be
// applied relative to the workspace folder, not the module root.
func TestDirectoryFilters_MultiRootImportScanning(t *testing.T) {
	const files = `
-- go.work --
go 1.18

use (
	a
	b
)
-- a/go.mod --
module mod1.test

go 1.18
-- a/main.go --
package main

func main() {
	hi.Hi()
}
-- a/hi/hi.go --
package hi

func Hi() {}
-- b/go.mod --
module mod2.test

go 1.18
-- b/main.go --
package main

func main() {
	hi.Hi()
}
-- b/hi/hi.go --
package hi

func Hi() {}
`

	WithOptions(
		Settings{
			"directoryFilters": []string{"-hi"}, // this test fails with -**/hi
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a/main.go")
		beforeSave := env.BufferText("a/main.go")
		env.OrganizeImports("a/main.go")
		got := env.BufferText("a/main.go")
		if got == beforeSave {
			t.Errorf("after organizeImports code action, got identical buffer:\n%s", got)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/fromenv_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"fmt"
	"path/filepath"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test that setting go.work via environment variables or settings works.
func TestUseGoWorkOutsideTheWorkspace(t *testing.T) {
	// As discussed in
	// https://github.com/golang/go/issues/59458#issuecomment-1513794691, we must
	// use \-separated paths in go.work use directives for this test to work
	// correctly on windows.
	var files = fmt.Sprintf(`
-- work/a/go.mod --
module a.com

go 1.12
-- work/a/a.go --
package a
-- work/b/go.mod --
module b.com

go 1.12
-- work/b/b.go --
package b

func _() {
	x := 1 // unused
}
-- other/c/go.mod --
module c.com

go 1.18
-- other/c/c.go --
package c
-- config/go.work --
go 1.18

use (
	%s
	%s
	%s
)
`,
		filepath.Join("$SANDBOX_WORKDIR", "work", "a"),
		filepath.Join("$SANDBOX_WORKDIR", "work", "b"),
		filepath.Join("$SANDBOX_WORKDIR", "other", "c"),
	)

	WithOptions(
		WorkspaceFolders("work"), // use a nested workspace dir, so that GOWORK is outside the workspace
		EnvVars{"GOWORK": filepath.Join("$SANDBOX_WORKDIR", "config", "go.work")},
	).Run(t, files, func(t *testing.T, env *Env) {
		// When we have an explicit GOWORK set, we should get a file watch request.
		env.OnceMet(
			InitialWorkspaceLoad,
			FileWatchMatching(`other`),
			FileWatchMatching(`config.go\.work`),
		)
		env.Await(FileWatchMatching(`config.go\.work`))
		// Even though work/b is not open, we should get its diagnostics as it is
		// included in the workspace.
		env.OpenFile("work/a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("work/b/b.go", "x := 1"), WithMessage("not used")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/goversion_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"flag"
	"os"
	"runtime"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

var go121bin = flag.String("go121bin", "", "bin directory containing go 1.21 or later")

// TODO(golang/go#65917): delete this test once we no longer support building
// gopls with older Go versions.
func TestCanHandlePatchVersions(t *testing.T) {
	// This test verifies the fixes for golang/go#66195 and golang/go#66636 --
	// that gopls does not crash when encountering a go version with a patch
	// number in the go.mod file.
	//
	// This is tricky to test, because the regression requires that gopls is
	// built with an older go version, and then the environment is upgraded to
	// have a more recent go. To set up this scenario, the test requires a path
	// to a bin directory containing go1.21 or later.
	if *go121bin == "" {
		t.Skip("-go121bin directory is not set")
	}

	if runtime.GOOS != "linux" && runtime.GOOS != "darwin" {
		t.Skip("requires linux or darwin") // for PATH separator
	}

	path := os.Getenv("PATH")
	t.Setenv("PATH", *go121bin+":"+path)

	const files = `
-- go.mod --
module example.com/bar

go 1.21.1

-- p.go --
package bar

type I interface { string }
`

	WithOptions(
		EnvVars{
			"PATH": path,
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.AfterChange(
			NoDiagnostics(ForFile("p.go")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/metadata_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TODO(rfindley): move workspace tests related to metadata bugs into this
// file.

func TestFixImportDecl(t *testing.T) {
	const src = `
-- go.mod --
module mod.test

go 1.12
-- p.go --
package p

import (
	_ "fmt"

const C = 42
`

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("p.go")
		env.RegexpReplace("p.go", "\"fmt\"", "\"fmt\"\n)")
		env.AfterChange(
			NoDiagnostics(ForFile("p.go")),
		)
	})
}

// Test that moving ignoring a file via build constraints causes diagnostics to
// be resolved.
func TestIgnoreFile(t *testing.T) {
	const src = `
-- go.mod --
module mod.test

go 1.12
-- foo.go --
package main

func main() {}
-- bar.go --
package main

func main() {}
	`

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("foo.go")
		env.OpenFile("bar.go")
		env.OnceMet(
			env.DoneWithOpen(),
			Diagnostics(env.AtRegexp("foo.go", "func (main)")),
			Diagnostics(env.AtRegexp("bar.go", "func (main)")),
		)

		// Ignore bar.go. This should resolve diagnostics.
		env.RegexpReplace("bar.go", "package main", "//go:build ignore\n\npackage main")

		// To make this test pass with experimentalUseInvalidMetadata, we could make
		// an arbitrary edit that invalidates the snapshot, at which point the
		// orphaned diagnostics will be invalidated.
		//
		// But of course, this should not be necessary: we should invalidate stale
		// information when fresh metadata arrives.
		// env.RegexpReplace("foo.go", "package main", "package main // test")
		env.AfterChange(
			NoDiagnostics(ForFile("foo.go")),
			NoDiagnostics(ForFile("bar.go")),
		)

		// If instead of 'ignore' (which gopls treats as a standalone package) we
		// used a different build tag, we should get a warning about having no
		// packages for bar.go
		env.RegexpReplace("bar.go", "ignore", "excluded")
		env.AfterChange(
			Diagnostics(env.AtRegexp("bar.go", "package (main)"), WithMessage("excluded due to its build tags")),
		)
	})
}

func TestReinitializeRepeatedly(t *testing.T) {
	const multiModule = `
-- go.work --
go 1.18

use (
	moda/a
	modb
)
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/go.sum --
b.com v1.2.3 h1:tXrlXP0rnjRpKNmkbLYoWBdq0ikb3C3bKK9//moAWBI=
b.com v1.2.3/go.mod h1:D+J7pfFBZK5vdIdZEFquR586vKKIkqG7Qjw9AxG5BQ8=
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
	// AAA
}
-- modb/go.mod --
module b.com

-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
`
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
		Settings{
			// For this test, we want workspace diagnostics to start immediately
			// during change processing.
			"diagnosticsDelay": "0",
		},
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.OpenFile("moda/a/a.go")
		env.AfterChange()

		// This test verifies that we fully process workspace reinitialization
		// (which allows GOPROXY), even when the reinitialized snapshot is
		// invalidated by subsequent changes.
		//
		// First, update go.work to remove modb. This will cause reinitialization
		// to fetch b.com from the proxy.
		env.WriteWorkspaceFile("go.work", "go 1.18\nuse moda/a")
		// Next, wait for gopls to start processing the change. Because we've set
		// diagnosticsDelay to zero, this will start diagnosing the workspace (and
		// try to reinitialize on the snapshot context).
		env.Await(env.StartedChangeWatchedFiles())
		// Finally, immediately make a file change to cancel the previous
		// operation. This is racy, but will usually cause initialization to be
		// canceled.
		env.RegexpReplace("moda/a/a.go", "AAA", "BBB")
		env.AfterChange()
		// Now, to satisfy a definition request, gopls will try to reload moda. But
		// without access to the proxy (because this is no longer a
		// reinitialization), this loading will fail.
		loc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		got := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "b.com@v1.2.3/b/b.go"; !strings.HasSuffix(got, want) {
			t.Errorf("expected %s, got %v", want, got)
		}
	})
}

// Test for golang/go#59458. With lazy module loading, we may not need
// transitively required modules.
func TestNestedModuleLoading_Issue59458(t *testing.T) {
	// In this test, module b.com/nested requires b.com/other, which in turn
	// requires b.com, but b.com/nested does not reach b.com through the package
	// graph. Therefore, b.com/nested does not need b.com on 1.17 and later,
	// thanks to graph pruning.
	//
	// We verify that we can load b.com/nested successfully. Previously, we
	// couldn't, because loading the pattern b.com/nested/... matched the module
	// b.com, which exists in the module graph but does not have a go.sum entry.

	const proxy = `
-- b.com@v1.2.3/go.mod --
module b.com

go 1.18
-- b.com@v1.2.3/b/b.go --
package b

func Hello() {}

-- b.com/other@v1.4.6/go.mod --
module b.com/other

go 1.18

require b.com v1.2.3
-- b.com/other@v1.4.6/go.sun --
b.com v1.2.3 h1:AGjCxWRJLUuJiZ21IUTByr9buoa6+B6Qh5LFhVLKpn4=
-- b.com/other@v1.4.6/bar/bar.go --
package bar

import "b.com/b"

func _() {
	b.Hello()
}
-- b.com/other@v1.4.6/foo/foo.go --
package foo

const Foo = 0
`

	const files = `
-- go.mod --
module b.com/nested

go 1.18

require b.com/other v1.4.6
-- nested.go --
package nested

import "b.com/other/foo"

const C = foo.Foo
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			NoDiagnostics(),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/misspelling_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"runtime"
	"testing"

	"golang.org/x/tools/gopls/internal/test/compare"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

// Test for golang/go#57081.
func TestFormattingMisspelledURI(t *testing.T) {
	if runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
		t.Skip("golang/go#57081 only reproduces on case-insensitive filesystems.")
	}
	const files = `
-- go.mod --
module mod.test

go 1.19
-- foo.go --
package foo

const  C = 2 // extra space is intentional
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("Foo.go")
		env.FormatBuffer("Foo.go")
		want := env.BufferText("Foo.go")

		if want == "" {
			t.Fatalf("Foo.go is empty")
		}

		// In golang/go#57081, we observed that if overlay cases don't match, gopls
		// will find (and format) the on-disk contents rather than the overlay,
		// resulting in invalid edits.
		//
		// Verify that this doesn't happen, by confirming that formatting is
		// idempotent.
		env.FormatBuffer("Foo.go")
		got := env.BufferText("Foo.go")
		if diff := compare.Text(want, got); diff != "" {
			t.Errorf("invalid content after second formatting:\n%s", diff)
		}
	})
}

// Test that we can find packages for open files with different spelling on
// case-insensitive file systems.
func TestPackageForMisspelledURI(t *testing.T) {
	t.Skip("golang/go#57081: this test fails because the Go command does not load Foo.go correctly")
	if runtime.GOOS != "windows" && runtime.GOOS != "darwin" {
		t.Skip("golang/go#57081 only reproduces on case-insensitive filesystems.")
	}
	const files = `
-- go.mod --
module mod.test

go 1.19
-- foo.go --
package foo

const C = D
-- bar.go --
package foo

const D = 2
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("Foo.go")
		env.AfterChange(NoDiagnostics())
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/modules_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestModulesCmd(t *testing.T) {
	const goModView = `
-- go.mod --
module foo

-- pkg/pkg.go --
package pkg
func Pkg()

-- bar/bar.go --
package bar
func Bar()

-- bar/baz/go.mod --
module baz

-- bar/baz/baz.go --
package baz
func Baz()
`

	const goWorkView = `
-- go.work --
use ./foo
use ./bar

-- foo/go.mod --
module foo

-- foo/foo.go --
package foo
func Foo()

-- bar/go.mod --
module bar

-- bar/bar.go --
package bar
func Bar()
`

	t.Run("go.mod view", func(t *testing.T) {
		// If baz isn't loaded, it will not be included
		t.Run("unloaded", func(t *testing.T) {
			Run(t, goModView, func(t *testing.T, env *Env) {
				checkModules(t, env, env.Editor.DocumentURI(""), -1, []command.Module{
					{
						Path:  "foo",
						GoMod: env.Editor.DocumentURI("go.mod"),
					},
				})
			})
		})

		// With baz loaded and recursion enabled, baz will be included
		t.Run("recurse", func(t *testing.T) {
			Run(t, goModView, func(t *testing.T, env *Env) {
				env.OpenFile("bar/baz/baz.go")
				checkModules(t, env, env.Editor.DocumentURI(""), -1, []command.Module{
					{
						Path:  "baz",
						GoMod: env.Editor.DocumentURI("bar/baz/go.mod"),
					},
					{
						Path:  "foo",
						GoMod: env.Editor.DocumentURI("go.mod"),
					},
				})
			})
		})

		// With recursion=1, baz will not be included
		t.Run("depth", func(t *testing.T) {
			Run(t, goModView, func(t *testing.T, env *Env) {
				env.OpenFile("bar/baz/baz.go")
				checkModules(t, env, env.Editor.DocumentURI(""), 1, []command.Module{
					{
						Path:  "foo",
						GoMod: env.Editor.DocumentURI("go.mod"),
					},
				})
			})
		})

		// Baz will be included if it is requested specifically
		t.Run("nested", func(t *testing.T) {
			Run(t, goModView, func(t *testing.T, env *Env) {
				env.OpenFile("bar/baz/baz.go")
				checkModules(t, env, env.Editor.DocumentURI("bar/baz"), 0, []command.Module{
					{
						Path:  "baz",
						GoMod: env.Editor.DocumentURI("bar/baz/go.mod"),
					},
				})
			})
		})
	})

	t.Run("go.work view", func(t *testing.T) {
		t.Run("base", func(t *testing.T) {
			Run(t, goWorkView, func(t *testing.T, env *Env) {
				checkModules(t, env, env.Editor.DocumentURI(""), 0, nil)
			})
		})

		t.Run("recursive", func(t *testing.T) {
			Run(t, goWorkView, func(t *testing.T, env *Env) {
				checkModules(t, env, env.Editor.DocumentURI(""), -1, []command.Module{
					{
						Path:  "bar",
						GoMod: env.Editor.DocumentURI("bar/go.mod"),
					},
					{
						Path:  "foo",
						GoMod: env.Editor.DocumentURI("foo/go.mod"),
					},
				})
			})
		})
	})
}

func checkModules(t testing.TB, env *Env, dir protocol.DocumentURI, maxDepth int, want []command.Module) {
	t.Helper()

	cmd := command.NewModulesCommand("Modules", command.ModulesArgs{Dir: dir, MaxDepth: maxDepth})
	var result command.ModulesResult
	env.ExecuteCommand(&protocol.ExecuteCommandParams{
		Command:   command.Modules.String(),
		Arguments: cmd.Arguments,
	}, &result)

	// The ordering of results is undefined and modules from a go.work view are
	// retrieved from a map, so sort the results to ensure consistency
	sort.Slice(result.Modules, func(i, j int) bool {
		a, b := result.Modules[i], result.Modules[j]
		return strings.Compare(a.Path, b.Path) < 0
	})

	diff := cmp.Diff(want, result.Modules)
	if diff != "" {
		t.Errorf("Modules(%v) returned unexpected diff (-want +got):\n%s", dir, diff)
	}
}


================================================
FILE: gopls/internal/test/integration/workspace/multi_folder_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

// TODO(rfindley): update the marker tests to support the concept of multiple
// workspace folders, and move this there.
func TestMultiView_Diagnostics(t *testing.T) {
	// In the past, gopls would only diagnose one View at a time
	// (the last to have changed).
	//
	// This test verifies that gopls can maintain diagnostics for multiple Views.
	const files = `

-- a/go.mod --
module golang.org/lsptests/a

go 1.20
-- a/a.go --
package a

func _() {
	x := 1 // unused
}
-- b/go.mod --
module golang.org/lsptests/b

go 1.20
-- b/b.go --
package b

func _() {
	y := 2 // unused
}
`

	WithOptions(
		WorkspaceFolders("a", "b"),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("a/a.go", "x")),
			Diagnostics(env.AtRegexp("b/b.go", "y")),
		)
	})
}

func TestMultiView_LocalReplace(t *testing.T) {
	// This is a regression test for #66145, where gopls attempted to load a
	// package in a locally replaced module as a workspace package, resulting in
	// spurious import diagnostics because the module graph had been pruned.

	const proxy = `
-- example.com/c@v1.2.3/go.mod --
module example.com/c

go 1.20

-- example.com/c@v1.2.3/c.go --
package c

const C = 3

`
	// In the past, gopls would only diagnose one View at a time
	// (the last to have changed).
	//
	// This test verifies that gopls can maintain diagnostics for multiple Views.
	const files = `
-- a/go.mod --
module golang.org/lsptests/a

go 1.20

require golang.org/lsptests/b v1.2.3

replace golang.org/lsptests/b => ../b

-- a/a.go --
package a

import "golang.org/lsptests/b"

const A = b.B - 1

-- b/go.mod --
module golang.org/lsptests/b

go 1.20

require example.com/c v1.2.3

-- b/go.sum --
example.com/c v1.2.3 h1:hsOPhoHQLZPEn7l3kNya3fR3SfqW0/rafZMP8ave6fg=
example.com/c v1.2.3/go.mod h1:4uG6Y5qX88LrEd4KfRoiguHZIbdLKUEHD1wXqPyrHcA=
-- b/b.go --
package b

const B = 2

-- b/unrelated/u.go --
package unrelated

import "example.com/c"

const U = c.C
`

	WithOptions(
		WorkspaceFolders("a", "b"),
		ProxyFiles(proxy),
	).Run(t, files, func(t *testing.T, env *Env) {
		// Opening unrelated first ensures that when we compute workspace packages
		// for the "a" workspace, it includes the unrelated package, which will be
		// unloadable from a as there is no a/go.sum.
		env.OpenFile("b/unrelated/u.go")
		env.AfterChange()
		env.OpenFile("a/a.go")
		env.AfterChange(NoDiagnostics())
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/packages_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestPackages(t *testing.T) {
	const files = `
-- go.mod --
module foo

-- foo.go --
package foo
func Foo()

-- bar/bar.go --
package bar
func Bar()

-- baz/go.mod --
module baz

-- baz/baz.go --
package baz
func Baz()
`

	t.Run("file", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("foo.go")}, false, 0, []command.Package{
				{
					Path:       "foo",
					ModulePath: "foo",
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{})
		})
	})

	t.Run("package", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("bar")}, false, 0, []command.Package{
				{
					Path:       "foo/bar",
					ModulePath: "foo",
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{})
		})
	})

	t.Run("workspace", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("")}, true, 0, []command.Package{
				{
					Path:       "foo",
					ModulePath: "foo",
				},
				{
					Path:       "foo/bar",
					ModulePath: "foo",
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{})
		})
	})

	t.Run("nested module", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			// Load the nested module
			env.OpenFile("baz/baz.go")

			// Request packages using the URI of the nested module _directory_
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("baz")}, true, 0, []command.Package{
				{
					Path:       "baz",
					ModulePath: "baz",
				},
			}, map[string]command.Module{
				"baz": {
					Path:  "baz",
					GoMod: env.Editor.DocumentURI("baz/go.mod"),
				},
			}, []string{})
		})
	})
}

func TestPackagesWithTests(t *testing.T) {
	const files = `
-- go.mod --
module foo

-- foo.go --
package foo
import "testing"
func Foo()
func TestFoo2(t *testing.T)
func foo()

-- foo_test.go --
package foo
import "testing"
func TestFoo(t *testing.T)
func Issue70927(*error)
func Test_foo(t *testing.T)

-- foo2_test.go --
package foo_test
import "testing"
func TestBar(t *testing.T) {}

-- baz/baz_test.go --
package baz
import "testing"
func TestBaz(*testing.T)
func BenchmarkBaz(*testing.B)
func FuzzBaz(*testing.F)
func ExampleBaz()

-- bat/go.mod --
module bat

-- bat/bat_test.go --
package bat
import "testing"
func Test(*testing.T)
`

	t.Run("file", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("foo_test.go")}, false, command.NeedTests, []command.Package{
				{
					Path:       "foo",
					ModulePath: "foo",
				},
				{
					Path:       "foo",
					ForTest:    "foo",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("foo_test.go"),
							Tests: []command.TestCase{
								{Name: "TestFoo"},
								{Name: "Test_foo"},
							},
						},
					},
				},
				{
					Path:       "foo_test",
					ForTest:    "foo",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("foo2_test.go"),
							Tests: []command.TestCase{
								{Name: "TestBar"},
							},
						},
					},
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{
				"func TestFoo(t *testing.T)",
				"func Test_foo(t *testing.T)",
				"func TestBar(t *testing.T) {}",
			})
		})
	})

	t.Run("package", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("baz")}, false, command.NeedTests, []command.Package{
				{
					Path:       "foo/baz",
					ForTest:    "foo/baz",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("baz/baz_test.go"),
							Tests: []command.TestCase{
								{Name: "TestBaz"},
								{Name: "BenchmarkBaz"},
								{Name: "FuzzBaz"},
								{Name: "ExampleBaz"},
							},
						},
					},
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{
				"func TestBaz(*testing.T)",
				"func BenchmarkBaz(*testing.B)",
				"func FuzzBaz(*testing.F)",
				"func ExampleBaz()",
			})
		})
	})

	t.Run("workspace", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI(".")}, true, command.NeedTests, []command.Package{
				{
					Path:       "foo",
					ModulePath: "foo",
				},
				{
					Path:       "foo",
					ForTest:    "foo",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("foo_test.go"),
							Tests: []command.TestCase{
								{Name: "TestFoo"},
								{Name: "Test_foo"},
							},
						},
					},
				},
				{
					Path:       "foo/baz",
					ForTest:    "foo/baz",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("baz/baz_test.go"),
							Tests: []command.TestCase{
								{Name: "TestBaz"},
								{Name: "BenchmarkBaz"},
								{Name: "FuzzBaz"},
								{Name: "ExampleBaz"},
							},
						},
					},
				},
				{
					Path:       "foo_test",
					ForTest:    "foo",
					ModulePath: "foo",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("foo2_test.go"),
							Tests: []command.TestCase{
								{Name: "TestBar"},
							},
						},
					},
				},
			}, map[string]command.Module{
				"foo": {
					Path:  "foo",
					GoMod: env.Editor.DocumentURI("go.mod"),
				},
			}, []string{
				"func TestFoo(t *testing.T)",
				"func Test_foo(t *testing.T)",
				"func TestBaz(*testing.T)",
				"func BenchmarkBaz(*testing.B)",
				"func FuzzBaz(*testing.F)",
				"func ExampleBaz()",
				"func TestBar(t *testing.T) {}",
			})
		})
	})

	t.Run("nested module", func(t *testing.T) {
		Run(t, files, func(t *testing.T, env *Env) {
			// Load the nested module
			env.OpenFile("bat/bat_test.go")

			// Request packages using the URI of the nested module _directory_
			checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("bat")}, true, command.NeedTests, []command.Package{
				{
					Path:       "bat",
					ForTest:    "bat",
					ModulePath: "bat",
					TestFiles: []command.TestFile{
						{
							URI: env.Editor.DocumentURI("bat/bat_test.go"),
							Tests: []command.TestCase{
								{Name: "Test"},
							},
						},
					},
				},
			}, map[string]command.Module{
				"bat": {
					Path:  "bat",
					GoMod: env.Editor.DocumentURI("bat/go.mod"),
				},
			}, []string{
				"func Test(*testing.T)",
			})
		})
	})
}

func TestPackagesWithSubtests(t *testing.T) {
	const files = `
-- go.mod --
module foo

-- foo_test.go --
package foo

import "testing"

// Verify that examples don't break subtest detection
func ExampleFoo() {}

func TestFoo(t *testing.T) {
	t.Run("Bar", func(t *testing.T) {
		t.Run("Baz", func(t *testing.T) {})
	})
	t.Run("Bar", func(t *testing.T) {})
	t.Run("Bar", func(t *testing.T) {})
	t.Run("with space", func(t *testing.T) {})

	var x X
	y := func(t *testing.T) {
		t.Run("VarSub", func(t *testing.T) {})
	}
	t.Run("SubtestFunc", SubtestFunc)
	t.Run("SubtestMethod", x.SubtestMethod)
	t.Run("SubtestVar", y)
}

func SubtestFunc(t *testing.T) {
	t.Run("FuncSub", func(t *testing.T) {})
}

type X int
func (X) SubtestMethod(t *testing.T) {
	t.Run("MethodSub", func(t *testing.T) {})
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("foo_test.go")}, false, command.NeedTests, []command.Package{
			{
				Path:       "foo",
				ForTest:    "foo",
				ModulePath: "foo",
				TestFiles: []command.TestFile{
					{
						URI: env.Editor.DocumentURI("foo_test.go"),
						Tests: []command.TestCase{
							{Name: "ExampleFoo"},
							{Name: "TestFoo"},
							{Name: "TestFoo/Bar"},
							{Name: "TestFoo/Bar/Baz"},
							{Name: "TestFoo/Bar#01"},
							{Name: "TestFoo/Bar#02"},
							{Name: "TestFoo/with_space"},
							{Name: "TestFoo/SubtestFunc"},
							{Name: "TestFoo/SubtestFunc/FuncSub"},
							{Name: "TestFoo/SubtestMethod"},
							{Name: "TestFoo/SubtestMethod/MethodSub"},
							{Name: "TestFoo/SubtestVar"},
							// {Name: "TestFoo/SubtestVar/VarSub"}, // TODO
						},
					},
				},
			},
		}, map[string]command.Module{
			"foo": {
				Path:  "foo",
				GoMod: env.Editor.DocumentURI("go.mod"),
			},
		}, []string{
			"func ExampleFoo() {}",
			`func TestFoo(t *testing.T) {
	t.Run("Bar", func(t *testing.T) {
		t.Run("Baz", func(t *testing.T) {})
	})
	t.Run("Bar", func(t *testing.T) {})
	t.Run("Bar", func(t *testing.T) {})
	t.Run("with space", func(t *testing.T) {})

	var x X
	y := func(t *testing.T) {
		t.Run("VarSub", func(t *testing.T) {})
	}
	t.Run("SubtestFunc", SubtestFunc)
	t.Run("SubtestMethod", x.SubtestMethod)
	t.Run("SubtestVar", y)
}`,
			"t.Run(\"Bar\", func(t *testing.T) {\n\t\tt.Run(\"Baz\", func(t *testing.T) {})\n\t})",
			`t.Run("Baz", func(t *testing.T) {})`,
			`t.Run("Bar", func(t *testing.T) {})`,
			`t.Run("Bar", func(t *testing.T) {})`,
			`t.Run("with space", func(t *testing.T) {})`,
			`t.Run("SubtestFunc", SubtestFunc)`,
			`t.Run("FuncSub", func(t *testing.T) {})`,
			`t.Run("SubtestMethod", x.SubtestMethod)`,
			`t.Run("MethodSub", func(t *testing.T) {})`,
			`t.Run("SubtestVar", y)`,
		})
	})
}

func TestRecursiveSubtest(t *testing.T) {
	const files = `
-- go.mod --
module foo

-- foo_test.go --
package foo

import "testing"

func TestFoo(t *testing.T) { t.Run("Foo", TestFoo) }
func TestBar(t *testing.T) { t.Run("Foo", TestFoo) }

func TestBaz(t *testing.T) {
	var sub func(t *testing.T)
	sub = func(t *testing.T) { t.Run("Sub", sub) }
	t.Run("Sub", sub)
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		checkPackages(t, env, []protocol.DocumentURI{env.Editor.DocumentURI("foo_test.go")}, false, command.NeedTests, []command.Package{
			{
				Path:       "foo",
				ForTest:    "foo",
				ModulePath: "foo",
				TestFiles: []command.TestFile{
					{
						URI: env.Editor.DocumentURI("foo_test.go"),
						Tests: []command.TestCase{
							{Name: "TestFoo"},
							{Name: "TestFoo/Foo"},
							{Name: "TestBar"},
							{Name: "TestBar/Foo"},
							{Name: "TestBaz"},
							{Name: "TestBaz/Sub"},
						},
					},
				},
			},
		}, map[string]command.Module{
			"foo": {
				Path:  "foo",
				GoMod: env.Editor.DocumentURI("go.mod"),
			},
		}, []string{
			`func TestFoo(t *testing.T) { t.Run("Foo", TestFoo) }`,
			`t.Run("Foo", TestFoo)`,
			`func TestBar(t *testing.T) { t.Run("Foo", TestFoo) }`,
			`t.Run("Foo", TestFoo)`,
			`func TestBaz(t *testing.T) {
	var sub func(t *testing.T)
	sub = func(t *testing.T) { t.Run("Sub", sub) }
	t.Run("Sub", sub)
}`,
			`t.Run("Sub", sub)`,
		})
	})
}

func checkPackages(t testing.TB, env *Env, files []protocol.DocumentURI, recursive bool, mode command.PackagesMode, wantPkg []command.Package, wantModule map[string]command.Module, wantSource []string) {
	t.Helper()

	cmd := command.NewPackagesCommand("Packages", command.PackagesArgs{Files: files, Recursive: recursive, Mode: mode})
	var result command.PackagesResult
	env.ExecuteCommand(&protocol.ExecuteCommandParams{
		Command:   command.Packages.String(),
		Arguments: cmd.Arguments,
	}, &result)

	// The ordering of packages is undefined so sort the results to ensure
	// consistency
	sort.Slice(result.Packages, func(i, j int) bool {
		a, b := result.Packages[i], result.Packages[j]
		c := strings.Compare(a.Path, b.Path)
		if c != 0 {
			return c < 0
		}
		return strings.Compare(a.ForTest, b.ForTest) < 0
	})

	// Instead of testing the exact values of the test locations (which would
	// make these tests significantly more trouble to maintain), verify the
	// source range they refer to.
	gotSource := []string{} // avoid issues with comparing null to []
	for i := range result.Packages {
		pkg := &result.Packages[i]
		for i := range pkg.TestFiles {
			file := &pkg.TestFiles[i]
			env.OpenFile(file.URI.Path())

			for i := range file.Tests {
				test := &file.Tests[i]
				gotSource = append(gotSource, env.FileContentAt(test.Loc))
				test.Loc = protocol.Location{}
			}
		}
	}

	if diff := cmp.Diff(wantPkg, result.Packages); diff != "" {
		t.Errorf("Packages(%v) returned unexpected packages (-want +got):\n%s", files, diff)
	}

	if diff := cmp.Diff(wantModule, result.Module); diff != "" {
		t.Errorf("Packages(%v) returned unexpected modules (-want +got):\n%s", files, diff)
	}

	// Don't check the source if the response is incorrect
	if !t.Failed() {
		if diff := cmp.Diff(wantSource, gotSource); diff != "" {
			t.Errorf("Packages(%v) returned unexpected test case ranges (-want +got):\n%s", files, diff)
		}
	}
}


================================================
FILE: gopls/internal/test/integration/workspace/quickfix_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/compare"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestQuickFix_UseModule(t *testing.T) {
	t.Skip("temporary skip for golang/go#57979: with zero-config gopls these files are no longer orphaned")

	const files = `
-- go.work --
go 1.20

use (
	./a
)
-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main

import "mod.com/a/lib"

func main() {
	_ = lib.C
}

-- a/lib/lib.go --
package lib

const C = "b"
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main

import "mod.com/b/lib"

func main() {
	_ = lib.C
}

-- b/lib/lib.go --
package lib

const C = "b"
`

	for _, title := range []string{
		"Use this module",
		"Use all modules",
	} {
		t.Run(title, func(t *testing.T) {
			Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("b/main.go")
				var d protocol.PublishDiagnosticsParams
				env.AfterChange(ReadDiagnostics("b/main.go", &d))
				fixes := env.GetQuickFixes("b/main.go", d.Diagnostics)
				var toApply []protocol.CodeAction
				for _, fix := range fixes {
					if strings.Contains(fix.Title, title) {
						toApply = append(toApply, fix)
					}
				}
				if len(toApply) != 1 {
					t.Fatalf("codeAction: got %d quick fixes matching %q, want 1; got: %v", len(toApply), title, toApply)
				}
				env.ApplyCodeAction(toApply[0])
				env.AfterChange(NoDiagnostics())
				want := `go 1.20

use (
	./a
	./b
)
`
				got := env.ReadWorkspaceFile("go.work")
				if diff := compare.Text(want, got); diff != "" {
					t.Errorf("unexpected go.work content:\n%s", diff)
				}
			})
		})
	}
}

func TestQuickFix_AddGoWork(t *testing.T) {
	t.Skip("temporary skip for golang/go#57979: with zero-config gopls these files are no longer orphaned")

	const files = `
-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main

import "mod.com/a/lib"

func main() {
	_ = lib.C
}

-- a/lib/lib.go --
package lib

const C = "b"
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main

import "mod.com/b/lib"

func main() {
	_ = lib.C
}

-- b/lib/lib.go --
package lib

const C = "b"
`

	tests := []struct {
		name  string
		file  string
		title string
		want  string // expected go.work content, excluding go directive line
	}{
		{
			"use b",
			"b/main.go",
			"Add a go.work file using this module",
			`
use ./b
`,
		},
		{
			"use a",
			"a/main.go",
			"Add a go.work file using this module",
			`
use ./a
`,
		},
		{
			"use all",
			"a/main.go",
			"Add a go.work file using all modules",
			`
use (
	./a
	./b
)
`,
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile(test.file)
				var d protocol.PublishDiagnosticsParams
				env.AfterChange(ReadDiagnostics(test.file, &d))
				fixes := env.GetQuickFixes(test.file, d.Diagnostics)
				var toApply []protocol.CodeAction
				for _, fix := range fixes {
					if strings.Contains(fix.Title, test.title) {
						toApply = append(toApply, fix)
					}
				}
				if len(toApply) != 1 {
					t.Fatalf("codeAction: got %d quick fixes matching %q, want 1; got: %v", len(toApply), test.title, toApply)
				}
				env.ApplyCodeAction(toApply[0])
				env.AfterChange(
					NoDiagnostics(ForFile(test.file)),
				)

				got := env.ReadWorkspaceFile("go.work")
				// Ignore the `go` directive, which we assume is on the first line of
				// the go.work file. This allows the test to be independent of go version.
				got = strings.Join(strings.Split(got, "\n")[1:], "\n")
				if diff := compare.Text(test.want, got); diff != "" {
					t.Errorf("unexpected go.work content:\n%s", diff)
				}
			})
		})
	}
}

func TestQuickFix_UnsavedGoWork(t *testing.T) {
	t.Skip("temporary skip for golang/go#57979: with zero-config gopls these files are no longer orphaned")

	const files = `
-- go.work --
go 1.21

use (
	./a
)
-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main

func main() {}
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main

func main() {}
`

	for _, title := range []string{
		"Use this module",
		"Use all modules",
	} {
		t.Run(title, func(t *testing.T) {
			Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("go.work")
				env.OpenFile("b/main.go")
				env.RegexpReplace("go.work", "go 1.21", "go 1.21 // arbitrary comment")
				var d protocol.PublishDiagnosticsParams
				env.AfterChange(ReadDiagnostics("b/main.go", &d))
				fixes := env.GetQuickFixes("b/main.go", d.Diagnostics)
				var toApply []protocol.CodeAction
				for _, fix := range fixes {
					if strings.Contains(fix.Title, title) {
						toApply = append(toApply, fix)
					}
				}
				if len(toApply) != 1 {
					t.Fatalf("codeAction: got %d quick fixes matching %q, want 1; got: %v", len(toApply), title, toApply)
				}
				fix := toApply[0]
				err := env.Editor.ApplyCodeAction(env.Ctx, fix)
				if err == nil {
					t.Fatalf("codeAction(%q) succeeded unexpectedly", fix.Title)
				}

				if got := err.Error(); !strings.Contains(got, "must save") {
					t.Errorf("codeAction(%q) returned error %q, want containing \"must save\"", fix.Title, err)
				}
			})
		})
	}
}

func TestQuickFix_GOWORKOff(t *testing.T) {
	t.Skip("temporary skip for golang/go#57979: with zero-config gopls these files are no longer orphaned")

	const files = `
-- go.work --
go 1.21

use (
	./a
)
-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main

func main() {}
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main

func main() {}
`

	for _, title := range []string{
		"Use this module",
		"Use all modules",
	} {
		t.Run(title, func(t *testing.T) {
			WithOptions(
				EnvVars{"GOWORK": "off"},
			).Run(t, files, func(t *testing.T, env *Env) {
				env.OpenFile("go.work")
				env.OpenFile("b/main.go")
				var d protocol.PublishDiagnosticsParams
				env.AfterChange(ReadDiagnostics("b/main.go", &d))
				fixes := env.GetQuickFixes("b/main.go", d.Diagnostics)
				var toApply []protocol.CodeAction
				for _, fix := range fixes {
					if strings.Contains(fix.Title, title) {
						toApply = append(toApply, fix)
					}
				}
				if len(toApply) != 1 {
					t.Fatalf("codeAction: got %d quick fixes matching %q, want 1; got: %v", len(toApply), title, toApply)
				}
				fix := toApply[0]
				err := env.Editor.ApplyCodeAction(env.Ctx, fix)
				if err == nil {
					t.Fatalf("codeAction(%q) succeeded unexpectedly", fix.Title)
				}

				if got := err.Error(); !strings.Contains(got, "GOWORK=off") {
					t.Errorf("codeAction(%q) returned error %q, want containing \"GOWORK=off\"", fix.Title, err)
				}
			})
		})
	}
}

func TestStubMethods64087(t *testing.T) {
	// We can't use the @fix or @quickfixerr or @codeaction
	// because the error now reported by the corrected logic
	// is internal and silently causes no fix to be offered.
	//
	// See also the similar TestStubMethods64545 below.

	const files = `
This is a regression test for a panic (issue #64087) in stub methods.

The illegal expression int("") caused a "cannot convert" error that
spuriously triggered the "stub methods" in a function whose return
statement had too many operands, leading to an out-of-bounds index.

-- go.mod --
module mod.com
go 1.18

-- a.go --
package a

func f() error {
	return nil, myerror{int("")}
}

type myerror struct{any}
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		// Expect a "wrong result count" diagnostic.
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(ReadDiagnostics("a.go", &d))

		// In no particular order, we expect:
		//  "...too many return values..." (compiler)
		//  "...cannot convert..." (compiler)
		// and possibly:
		//  "...too many return values..." (fillreturns)
		// We check only for the first of these.
		found := false
		for i, diag := range d.Diagnostics {
			t.Logf("Diagnostics[%d] = %q (%s)", i, diag.Message, diag.Source)
			if strings.Contains(diag.Message, "too many return") {
				found = true
			}
		}
		if !found {
			t.Fatalf("Expected WrongResultCount diagnostic not found.")
		}

		// GetQuickFixes should not panic (the original bug).
		fixes := env.GetQuickFixes("a.go", d.Diagnostics)

		// We should not be offered a "stub methods" fix.
		for _, fix := range fixes {
			if strings.Contains(fix.Title, "Implement error") {
				t.Errorf("unexpected 'stub methods' fix: %#v", fix)
			}
		}
	})
}

func TestStubMethods64545(t *testing.T) {
	// We can't use the @fix or @quickfixerr or @codeaction
	// because the error now reported by the corrected logic
	// is internal and silently causes no fix to be offered.
	//
	// TODO(adonovan): we may need to generalize this test and
	// TestStubMethods64087 if this happens a lot.

	const files = `
This is a regression test for a panic (issue #64545) in stub methods.

The illegal expression int("") caused a "cannot convert" error that
spuriously triggered the "stub methods" in a function whose var
spec had no RHS values, leading to an out-of-bounds index.

-- go.mod --
module mod.com
go 1.18

-- a.go --
package a

var _ [int("")]byte
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")

		// Expect a "cannot convert" diagnostic, and perhaps others.
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(ReadDiagnostics("a.go", &d))

		found := false
		for i, diag := range d.Diagnostics {
			t.Logf("Diagnostics[%d] = %q (%s)", i, diag.Message, diag.Source)
			if strings.Contains(diag.Message, "cannot convert") {
				found = true
			}
		}
		if !found {
			t.Fatalf("Expected 'cannot convert' diagnostic not found.")
		}

		// GetQuickFixes should not panic (the original bug).
		fixes := env.GetQuickFixes("a.go", d.Diagnostics)

		// We should not be offered a "stub methods" fix.
		for _, fix := range fixes {
			if strings.Contains(fix.Title, "Implement error") {
				t.Errorf("unexpected 'stub methods' fix: %#v", fix)
			}
		}
	})
}

// quick fix didn't offer add imports
func TestIssue70755(t *testing.T) {
	files := `
-- go.mod --
module failure.com
go 1.23
-- bar/bar.go --
package notbar
type NotBar struct{}
-- baz/baz.go --
package baz
type Baz struct{}
-- foo/foo.go --
package foo
type foo struct {
bar notbar.NotBar
bzz baz.Baz
}
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("foo/foo.go")
		var d protocol.PublishDiagnosticsParams
		env.AfterChange(ReadDiagnostics("foo/foo.go", &d))
		// should get two, one for undefined notbar
		// and one for undefined baz
		fixes := env.GetQuickFixes("foo/foo.go", d.Diagnostics)
		if len(fixes) != 2 {
			t.Fatalf("got %v, want 2 quick fixes", fixes)
		}
		good := 0
		var failures strings.Builder
		for _, f := range fixes {
			ti := f.Title
			// these may be overly white-space sensitive
			if ti == "Add import: notbar \"failure.com/bar\"" ||
				ti == "Add import:  \"failure.com/baz\"" {
				good++
			} else {
				failures.WriteString(ti)
			}
		}
		if good != 2 {
			t.Errorf("failed to find\n%q, got\n%q\n%q", failures.String(), fixes[0].Title,
				fixes[1].Title)
		}

	})
}


================================================
FILE: gopls/internal/test/integration/workspace/standalone_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"sort"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestStandaloneFiles(t *testing.T) {
	const files = `
-- go.mod --
module mod.test

go 1.16
-- lib/lib.go --
package lib

const K = 0

type I interface {
	M()
}
-- lib/ignore.go --
//go:build ignore

package main

import (
	"mod.test/lib"
)

const K = 1

type Mer struct{}
func (Mer) M()

func main() {
	println(lib.K + K)
}
`
	WithOptions(
		// On Go 1.17 and earlier, this test fails with
		// experimentalWorkspaceModule. Not investigated, as
		// experimentalWorkspaceModule will be removed.
		Modes(Default),
	).Run(t, files, func(t *testing.T, env *Env) {
		// Initially, gopls should not know about the standalone file as it hasn't
		// been opened. Therefore, we should only find one symbol 'K'.
		//
		// (The choice of "K" is a little sleazy: it was originally "C" until
		// we started adding "unsafe" to the workspace unconditionally, which
		// caused a spurious match of "unsafe.Slice". But in practice every
		// workspace depends on unsafe.)
		syms := env.Symbol("K")
		if got, want := len(syms), 1; got != want {
			t.Errorf("got %d symbols, want %d (%+v)", got, want, syms)
		}

		// Similarly, we should only find one reference to "K", and no
		// implementations of I.
		checkLocations := func(method string, gotLocations []protocol.Location, wantFiles ...string) {
			var gotFiles []string
			for _, l := range gotLocations {
				gotFiles = append(gotFiles, env.Sandbox.Workdir.URIToPath(l.URI))
			}
			sort.Strings(gotFiles)
			sort.Strings(wantFiles)
			if diff := cmp.Diff(wantFiles, gotFiles); diff != "" {
				t.Errorf("%s(...): unexpected locations (-want +got):\n%s", method, diff)
			}
		}

		env.OpenFile("lib/lib.go")
		env.AfterChange(NoDiagnostics())

		// Replacing K with D should not cause any workspace diagnostics, since we
		// haven't yet opened the standalone file.
		env.RegexpReplace("lib/lib.go", "K", "D")
		env.AfterChange(NoDiagnostics())
		env.RegexpReplace("lib/lib.go", "D", "K")
		env.AfterChange(NoDiagnostics())

		refs := env.References(env.RegexpSearch("lib/lib.go", "K"))
		checkLocations("References", refs, "lib/lib.go")

		impls := env.Implementations(env.RegexpSearch("lib/lib.go", "I"))
		checkLocations("Implementations", impls) // no implementations

		// Opening the standalone file should not result in any diagnostics.
		env.OpenFile("lib/ignore.go")
		env.AfterChange(NoDiagnostics())

		// Having opened the standalone file, we should find its symbols in the
		// workspace.
		syms = env.Symbol("K")
		if got, want := len(syms), 2; got != want {
			t.Fatalf("got %d symbols, want %d", got, want)
		}

		foundMainK := false
		var symNames []string
		for _, sym := range syms {
			symNames = append(symNames, sym.Name)
			if sym.Name == "main.K" {
				foundMainK = true
			}
		}
		if !foundMainK {
			t.Errorf("WorkspaceSymbol(\"K\") = %v, want containing main.K", symNames)
		}

		// We should resolve workspace definitions in the standalone file.
		fileLoc := env.FirstDefinition(env.RegexpSearch("lib/ignore.go", "lib.(K)"))
		file := env.Sandbox.Workdir.URIToPath(fileLoc.URI)
		if got, want := file, "lib/lib.go"; got != want {
			t.Errorf("Definition(lib.K) = %v, want %v", got, want)
		}

		// ...as well as intra-file definitions
		loc := env.FirstDefinition(env.RegexpSearch("lib/ignore.go", "\\+ (K)"))
		wantLoc := env.RegexpSearch("lib/ignore.go", "const (K)")
		if loc != wantLoc {
			t.Errorf("Definition(K) = %v, want %v", loc, wantLoc)
		}

		// Renaming "lib.K" to "lib.D" should cause a diagnostic in the standalone
		// file.
		env.RegexpReplace("lib/lib.go", "K", "D")
		env.AfterChange(Diagnostics(env.AtRegexp("lib/ignore.go", "lib.(K)")))

		// Undoing the replacement should fix diagnostics
		env.RegexpReplace("lib/lib.go", "D", "K")
		env.AfterChange(NoDiagnostics())

		// Now that our workspace has no errors, we should be able to find
		// references and rename.
		refs = env.References(env.RegexpSearch("lib/lib.go", "K"))
		checkLocations("References", refs, "lib/lib.go", "lib/ignore.go")

		impls = env.Implementations(env.RegexpSearch("lib/lib.go", "I"))
		checkLocations("Implementations", impls, "lib/ignore.go")

		// Renaming should rename in the standalone package.
		env.Rename(env.RegexpSearch("lib/lib.go", "K"), "D")
		env.RegexpSearch("lib/ignore.go", "lib.D")
	})
}

func TestStandaloneFiles_Configuration(t *testing.T) {
	const files = `
-- go.mod --
module mod.test

go 1.18
-- lib.go --
package lib // without this package, files are loaded as command-line-arguments
-- ignore.go --
//go:build ignore

package main

// An arbitrary comment.

func main() {}
-- standalone.go --
//go:build standalone

package main

func main() {}
`

	WithOptions(
		Settings{
			"standaloneTags": []string{"standalone", "script"},
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("ignore.go")
		env.OpenFile("standalone.go")

		env.AfterChange(
			Diagnostics(env.AtRegexp("ignore.go", "package (main)")),
			NoDiagnostics(ForFile("standalone.go")),
		)

		cfg := env.Editor.Config()
		cfg.Settings = map[string]any{
			"standaloneTags": []string{"ignore"},
		}
		env.ChangeConfiguration(cfg)
		env.AfterChange(
			NoDiagnostics(ForFile("ignore.go")),
			Diagnostics(env.AtRegexp("standalone.go", "package (main)")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/std_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestStdWorkspace(t *testing.T) {
	// This test checks that we actually load workspace packages when opening
	// GOROOT.
	//
	// In golang/go#65801, we failed to do this because go/packages returns nil
	// Module for std and cmd.
	//
	// Because this test loads std as a workspace, it may be slow on smaller
	// builders.
	if testing.Short() {
		t.Skip("skipping with -short: loads GOROOT")
	}

	// The test also fails on Windows because an absolute path does not match
	// (likely a misspelling due to slashes).
	// TODO(rfindley): investigate and fix this on windows.
	if runtime.GOOS == "windows" {
		t.Skip("skipping on windows: fails to misspelled paths")
	}

	// Query GOROOT. This is slightly more precise than e.g. runtime.GOROOT, as
	// it queries the go command in the environment.
	cmd := exec.Command("go", "env", "GOROOT")
	// Run with GOTOOLCHAIN=local so as to not be affected by toolchain upgrades
	// in the current directory (which is affected by gopls' go.mod file).
	// This was golang/go#70187
	cmd.Env = append(os.Environ(), "GOTOOLCHAIN=local")
	goroot, err := cmd.Output()
	if err != nil {
		t.Fatal(err)
	}
	stdDir := filepath.Join(strings.TrimSpace(string(goroot)), "src")
	WithOptions(
		Modes(Default), // This test may be slow. No reason to run it multiple times.
		WorkspaceFolders(stdDir),
	).Run(t, "", func(t *testing.T, env *Env) {
		// Find parser.ParseFile. Query with `'` to get an exact match.
		syms := env.Symbol("'go/parser.ParseFile")
		if len(syms) != 1 {
			t.Fatalf("got %d symbols, want exactly 1. Symbols:\n%v", len(syms), syms)
		}
		parserPath := syms[0].Location.URI.Path()
		env.OpenFile(parserPath)

		// Find the reference to ast.File from the signature of ParseFile. This
		// helps guard against matching a comment.
		astFile := env.RegexpSearch(parserPath, `func ParseFile\(.*ast\.(File)`)
		refs := env.References(astFile)

		// If we've successfully loaded workspace packages for std, we should find
		// a reference in go/types.
		foundGoTypesReference := false
		for _, ref := range refs {
			if strings.Contains(string(ref.URI), "go/types") {
				foundGoTypesReference = true
			}
		}
		if !foundGoTypesReference {
			t.Errorf("references(ast.File) did not return a go/types reference. Refs:\n%v", refs)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/vendor_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"testing"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestWorkspacePackagesExcludesVendor(t *testing.T) {
	// This test verifies that packages in the vendor directory are not workspace
	// packages. This would be an easy mistake for gopls to make, since mod
	// vendoring excludes go.mod files, and therefore the nearest go.mod file for
	// vendored packages is often the workspace mod file.
	const proxy = `
-- other.com/b@v1.0.0/go.mod --
module other.com/b

go 1.18

-- other.com/b@v1.0.0/b.go --
package b

type B int

func _() {
	var V int // unused
}
`
	const src = `
-- go.mod --
module example.com/a
go 1.14
require other.com/b v1.0.0

-- a.go --
package a

import "other.com/b"

var _ b.B

`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
		Modes(Default),
	).Run(t, src, func(t *testing.T, env *Env) {
		env.RunGoCommand("mod", "vendor")
		// Uncomment for updated go.sum contents.
		// env.DumpGoSum(".")
		env.OpenFile("a.go")
		env.AfterChange(
			NoDiagnostics(), // as b is not a workspace package
		)
		loc := env.FirstDefinition(env.RegexpSearch("a.go", `b\.(B)`))
		env.OpenFile(env.Sandbox.Workdir.URIToPath(loc.URI))
		env.AfterChange(
			Diagnostics(env.AtRegexp("vendor/other.com/b/b.go", "V"), WithMessage("not used")),
		)
	})
}


================================================
FILE: gopls/internal/test/integration/workspace/workspace_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"context"
	"fmt"
	"os"
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/goversion"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/testenv"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	os.Exit(Main(m))
}

const workspaceProxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

import "fmt"

func SaySomething() {
	fmt.Println("something")
}
-- random.org@v1.2.3/go.mod --
module random.org

go 1.12
-- random.org@v1.2.3/bye/bye.go --
package bye

func Goodbye() {
	println("Bye")
}
`

// TODO: Add a replace directive.
const workspaceModule = `
-- pkg/go.mod --
module mod.com

go 1.14

require (
	example.com v1.2.3
	random.org v1.2.3
)
-- pkg/go.sum --
example.com v1.2.3 h1:veRD4tUnatQRgsULqULZPjeoBGFr2qBhevSCZllD2Ds=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
random.org v1.2.3 h1:+JE2Fkp7gS0zsHXGEQJ7hraom3pNTlkxC4b2qPfA+/Q=
random.org v1.2.3/go.mod h1:E9KM6+bBX2g5ykHZ9H27w16sWo3QwgonyjM44Dnej3I=
-- pkg/main.go --
package main

import (
	"example.com/blah"
	"mod.com/inner"
	"random.org/bye"
)

func main() {
	blah.SaySomething()
	inner.Hi()
	bye.Goodbye()
}
-- pkg/main2.go --
package main

import "fmt"

func _() {
	fmt.Print("%s")
}
-- pkg/inner/inner.go --
package inner

import "example.com/blah"

func Hi() {
	blah.SaySomething()
}
-- goodbye/bye/bye.go --
package bye

func Bye() {}
-- goodbye/go.mod --
module random.org

go 1.12
`

// Confirm that find references returns all of the references in the module,
// regardless of what the workspace root is.
func TestReferences(t *testing.T) {
	for _, tt := range []struct {
		name, rootPath string
	}{
		{
			name:     "module root",
			rootPath: "pkg",
		},
		{
			name:     "subdirectory",
			rootPath: "pkg/inner",
		},
	} {
		t.Run(tt.name, func(t *testing.T) {
			opts := []RunOption{ProxyFiles(workspaceProxy)}
			if tt.rootPath != "" {
				opts = append(opts, WorkspaceFolders(tt.rootPath))
			}
			WithOptions(opts...).Run(t, workspaceModule, func(t *testing.T, env *Env) {
				f := "pkg/inner/inner.go"
				env.OpenFile(f)
				locations := env.References(env.RegexpSearch(f, `SaySomething`))
				want := 3
				if got := len(locations); got != want {
					t.Fatalf("expected %v locations, got %v", want, got)
				}
			})
		})
	}
}

// Make sure that analysis diagnostics are cleared for the whole package when
// the only opened file is closed. This test was inspired by the experience in
// VS Code, where clicking on a reference result triggers a
// textDocument/didOpen without a corresponding textDocument/didClose.
func TestClearAnalysisDiagnostics(t *testing.T) {
	WithOptions(
		ProxyFiles(workspaceProxy),
		WorkspaceFolders("pkg/inner"),
	).Run(t, workspaceModule, func(t *testing.T, env *Env) {
		env.OpenFile("pkg/main.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("pkg/main2.go", "fmt.Print")),
		)
		env.CloseBuffer("pkg/main.go")
		env.AfterChange(
			NoDiagnostics(ForFile("pkg/main2.go")),
		)
	})
}

// TestReloadOnlyOnce checks that changes to the go.mod file do not result in
// redundant package loads (golang/go#54473).
//
// Note that this test may be fragile, as it depends on specific structure to
// log messages around reinitialization. Nevertheless, it is important for
// guarding against accidentally duplicate reloading.
func TestReloadOnlyOnce(t *testing.T) {
	WithOptions(
		ProxyFiles(workspaceProxy),
		WorkspaceFolders("pkg"),
	).Run(t, workspaceModule, func(t *testing.T, env *Env) {
		dir := env.Sandbox.Workdir.URI("goodbye").Path()
		goModWithReplace := fmt.Sprintf(`%s
replace random.org => %s
`, env.ReadWorkspaceFile("pkg/go.mod"), dir)
		env.WriteWorkspaceFile("pkg/go.mod", goModWithReplace)
		env.Await(
			LogMatching(protocol.Info, `packages\.Load #\d+\n`, 2, false),
		)
	})
}

const workspaceModuleProxy = `
-- example.com@v1.2.3/go.mod --
module example.com

go 1.12
-- example.com@v1.2.3/blah/blah.go --
package blah

import "fmt"

func SaySomething() {
	fmt.Println("something")
}
-- b.com@v1.2.3/go.mod --
module b.com

go 1.12
-- b.com@v1.2.3/b/b.go --
package b

func Hello() {}
`

const multiModule = `
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/go.sum --
b.com v1.2.3 h1:tXrlXP0rnjRpKNmkbLYoWBdq0ikb3C3bKK9//moAWBI=
b.com v1.2.3/go.mod h1:D+J7pfFBZK5vdIdZEFquR586vKKIkqG7Qjw9AxG5BQ8=
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
-- modb/go.mod --
module b.com

-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
`

func TestAutomaticWorkspaceModule_Interdependent(t *testing.T) {
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.RunGoCommand("work", "init")
		env.RunGoCommand("work", "use", "-r", ".")
		env.AfterChange(
			Diagnostics(env.AtRegexp("moda/a/a.go", "x")),
			Diagnostics(env.AtRegexp("modb/b/b.go", "x")),
			NoDiagnostics(env.AtRegexp("moda/a/a.go", `"b.com/b"`)),
		)
	})
}

func TestWorkspaceVendoring(t *testing.T) {
	testenv.NeedsGoCommand1Point(t, 22)
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.RunGoCommand("work", "init")
		env.RunGoCommand("work", "use", "moda/a")
		env.AfterChange()
		env.OpenFile("moda/a/a.go")
		env.RunGoCommand("work", "vendor")
		env.AfterChange()
		loc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "b.(Hello)"))
		const want = "vendor/b.com/b/b.go"
		if got := env.Sandbox.Workdir.URIToPath(loc.URI); got != want {
			t.Errorf("Definition: got location %q, want %q", got, want)
		}
	})
}

func TestModuleWithExclude(t *testing.T) {
	const proxy = `
-- c.com@v1.2.3/go.mod --
module c.com

go 1.12

require b.com v1.2.3
-- c.com@v1.2.3/blah/blah.go --
package blah

import "fmt"

func SaySomething() {
	fmt.Println("something")
}
-- b.com@v1.2.3/go.mod --
module b.com

go 1.12
-- b.com@v1.2.4/b/b.go --
package b

func Hello() {}
-- b.com@v1.2.4/go.mod --
module b.com

go 1.12
`
	const files = `
-- go.mod --
module a.com

require c.com v1.2.3

exclude b.com v1.2.3
-- main.go --
package a

func main() {
	var x int
}
`
	WithOptions(
		WriteGoSum("."),
		ProxyFiles(proxy),
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			Diagnostics(env.AtRegexp("main.go", "x")),
		)
	})
}

// This change tests that the version of the module used changes after it has
// been deleted from the workspace.
//
// TODO(golang/go#55331): delete this placeholder along with experimental
// workspace module.
func TestDeleteModule_Interdependent(t *testing.T) {
	const multiModule = `
-- go.work --
go 1.18

use (
	moda/a
	modb
)
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/go.sum --
b.com v1.2.3 h1:tXrlXP0rnjRpKNmkbLYoWBdq0ikb3C3bKK9//moAWBI=
b.com v1.2.3/go.mod h1:D+J7pfFBZK5vdIdZEFquR586vKKIkqG7Qjw9AxG5BQ8=
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
-- modb/go.mod --
module b.com

-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
`
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.OpenFile("moda/a/a.go")
		env.Await(env.DoneWithOpen())

		originalLoc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		original := env.Sandbox.Workdir.URIToPath(originalLoc.URI)
		if want := "modb/b/b.go"; !strings.HasSuffix(original, want) {
			t.Errorf("expected %s, got %v", want, original)
		}
		env.AfterChange()

		env.RemoveWorkspaceFile("modb/b/b.go")
		env.RemoveWorkspaceFile("modb/go.mod")
		env.WriteWorkspaceFile("go.work", "go 1.18\nuse moda/a")
		env.AfterChange()

		gotLoc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		got := env.Sandbox.Workdir.URIToPath(gotLoc.URI)
		if want := "b.com@v1.2.3/b/b.go"; !strings.HasSuffix(got, want) {
			t.Errorf("expected %s, got %v", want, got)
		}
	})
}

// Tests that the version of the module used changes after it has been added
// to the workspace.
func TestCreateModule_Interdependent(t *testing.T) {
	const multiModule = `
-- go.work --
go 1.18

use (
	moda/a
)
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/go.sum --
b.com v1.2.3 h1:tXrlXP0rnjRpKNmkbLYoWBdq0ikb3C3bKK9//moAWBI=
b.com v1.2.3/go.mod h1:D+J7pfFBZK5vdIdZEFquR586vKKIkqG7Qjw9AxG5BQ8=
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
`
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.OpenFile("moda/a/a.go")
		loc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		original := env.Sandbox.Workdir.URIToPath(loc.URI)
		if want := "b.com@v1.2.3/b/b.go"; !strings.HasSuffix(original, want) {
			t.Errorf("expected %s, got %v", want, original)
		}
		env.WriteWorkspaceFiles(map[string]string{
			"go.work": `go 1.18

use (
	moda/a
	modb
)
`,
			"modb/go.mod": "module b.com",
			"modb/b/b.go": `package b

func Hello() int {
	var x int
}
`,
		})
		env.AfterChange(Diagnostics(env.AtRegexp("modb/b/b.go", "x")))
		gotLoc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		got := env.Sandbox.Workdir.URIToPath(gotLoc.URI)
		if want := "modb/b/b.go"; !strings.HasSuffix(got, want) {
			t.Errorf("expected %s, got %v", want, original)
		}
	})
}

// This test confirms that a gopls workspace can recover from initialization
// with one invalid module.
func TestOneBrokenModule(t *testing.T) {
	const multiModule = `
-- go.work --
go 1.18

use (
	moda/a
	modb
)
-- moda/a/go.mod --
module a.com

require b.com v1.2.3

-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
-- modb/go.mod --
modul b.com // typo here

-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
`
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.OpenFile("modb/go.mod")
		env.AfterChange(
			Diagnostics(AtPosition("modb/go.mod", 0, 0)),
		)
		env.RegexpReplace("modb/go.mod", "modul", "module")
		env.SaveBufferWithoutActions("modb/go.mod")
		env.AfterChange(
			Diagnostics(env.AtRegexp("modb/b/b.go", "x")),
		)
	})
}

// TestBadGoWork exercises the panic from golang/vscode-go#2121.
func TestBadGoWork(t *testing.T) {
	const files = `
-- go.work --
use ./bar
-- bar/go.mod --
module example.com/bar
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")
	})
}

func TestUseGoWork(t *testing.T) {
	// This test validates certain functionality related to using a go.work
	// file to specify workspace modules.
	const multiModule = `
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/go.sum --
b.com v1.2.3 h1:tXrlXP0rnjRpKNmkbLYoWBdq0ikb3C3bKK9//moAWBI=
b.com v1.2.3/go.mod h1:D+J7pfFBZK5vdIdZEFquR586vKKIkqG7Qjw9AxG5BQ8=
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
-- modb/go.mod --
module b.com

require example.com v1.2.3
-- modb/go.sum --
example.com v1.2.3 h1:Yryq11hF02fEf2JlOS2eph+ICE2/ceevGV3C9dl5V/c=
example.com v1.2.3/go.mod h1:Y2Rc5rVWjWur0h3pd9aEvK5Pof8YKDANh9gHA2Maujo=
-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
-- go.work --
go 1.17

use (
	./moda/a
)
`
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
		Settings{
			"subdirWatchPatterns": "on",
		},
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		// Initially, the go.work should cause only the a.com module to be loaded,
		// so we shouldn't get any file watches for modb. Further validate this by
		// jumping to a definition in b.com and ensuring that we go to the module
		// cache.
		env.OnceMet(
			InitialWorkspaceLoad,
			NoFileWatchMatching("modb"),
		)
		env.OpenFile("moda/a/a.go")
		env.Await(env.DoneWithOpen())

		// To verify which modules are loaded, we'll jump to the definition of
		// b.Hello.
		checkHelloLocation := func(want string) error {
			loc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
			file := env.Sandbox.Workdir.URIToPath(loc.URI)
			if !strings.HasSuffix(file, want) {
				return fmt.Errorf("expected %s, got %v", want, file)
			}
			return nil
		}

		// Initially this should be in the module cache, as b.com is not replaced.
		if err := checkHelloLocation("b.com@v1.2.3/b/b.go"); err != nil {
			t.Fatal(err)
		}

		// Now, modify the go.work file on disk to activate the b.com module in
		// the workspace.
		env.WriteWorkspaceFile("go.work", `
go 1.17

use (
	./moda/a
	./modb
)
`)

		// As of golang/go#54069, writing go.work to the workspace triggers a
		// workspace reload, and new file watches.
		env.AfterChange(
			Diagnostics(env.AtRegexp("modb/b/b.go", "x")),
			// TODO(golang/go#60340): we don't get a file watch yet, because
			// updateWatchedDirectories runs before snapshot.load. Instead, we get it
			// after the next change (the didOpen below).
			// FileWatchMatching("modb"),
		)

		// Jumping to definition should now go to b.com in the workspace.
		if err := checkHelloLocation("modb/b/b.go"); err != nil {
			t.Fatal(err)
		}

		// Now, let's modify the go.work *overlay* (not on disk), and verify that
		// this change is only picked up once it is saved.
		env.OpenFile("go.work")
		env.AfterChange(
			// TODO(golang/go#60340): delete this expectation in favor of
			// the commented-out expectation above, once we fix the evaluation order
			// of file watches. We should not have to wait for a second change to get
			// the correct watches.
			FileWatchMatching("modb"),
		)
		env.SetBufferContent("go.work", `go 1.17

use (
	./moda/a
)`)

		// Simply modifying the go.work file does not cause a reload, so we should
		// still jump within the workspace.
		//
		// TODO: should editing the go.work above cause modb diagnostics to be
		// suppressed?
		env.AfterChange()
		if err := checkHelloLocation("modb/b/b.go"); err != nil {
			t.Fatal(err)
		}

		// Saving should reload the workspace.
		env.SaveBufferWithoutActions("go.work")
		if err := checkHelloLocation("b.com@v1.2.3/b/b.go"); err != nil {
			t.Fatal(err)
		}

		// Since no file in modb is open, there should be no view containing
		// modb/go.mod, and we should clear its diagnostics.
		env.AfterChange(NoDiagnostics(ForFile("modb/go.mod")))

		// Test Formatting.
		env.SetBufferContent("go.work", `go 1.18
  use      (



		./moda/a
)
`) // TODO(matloob): For some reason there's a "start position 7:0 is out of bounds" error when the ")" is on the last character/line in the file. Rob probably knows what's going on.
		env.SaveBuffer("go.work")
		env.AfterChange()
		gotWorkContents := env.ReadWorkspaceFile("go.work")
		wantWorkContents := `go 1.18

use (
	./moda/a
)
`
		if gotWorkContents != wantWorkContents {
			t.Fatalf("formatted contents of workspace: got %q; want %q", gotWorkContents, wantWorkContents)
		}
	})
}

func TestUseGoWorkDiagnosticMissingModule(t *testing.T) {
	const files = `
-- go.work --
go 1.18

use ./foo
-- bar/go.mod --
module example.com/bar
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.work", "use"), WithMessage("directory ./foo does not contain a module")),
		)
		// The following tests is a regression test against an issue where we weren't
		// copying the workFile struct field on workspace when a new one was created in
		// (*workspace).invalidate. Set the buffer content to a working file so that
		// invalidate recognizes the workspace to be change and copies over the workspace
		// struct, and then set the content back to the old contents to make sure
		// the diagnostic still shows up.
		env.SetBufferContent("go.work", "go 1.18 \n\n use ./bar\n")
		env.AfterChange(
			NoDiagnostics(env.AtRegexp("go.work", "use")),
		)
		env.SetBufferContent("go.work", "go 1.18 \n\n use ./foo\n")
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.work", "use"), WithMessage("directory ./foo does not contain a module")),
		)
	})
}

func TestUseGoWorkDiagnosticSyntaxError(t *testing.T) {
	const files = `
-- go.work --
go 1.18

usa ./foo
replace
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.work", "usa"), WithMessage("unknown directive: usa")),
			Diagnostics(env.AtRegexp("go.work", "replace"), WithMessage("usage: replace")),
		)
	})
}

func TestUseGoWorkHover(t *testing.T) {
	const files = `
-- go.work --
go 1.18

use ./foo
use (
	./bar
	./bar/baz
)
-- foo/go.mod --
module example.com/foo
-- bar/go.mod --
module example.com/bar
-- bar/baz/go.mod --
module example.com/bar/baz
`
	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("go.work")

		tcs := map[string]string{
			`\./foo`:      "example.com/foo",
			`(?m)\./bar$`: "example.com/bar",
			`\./bar/baz`:  "example.com/bar/baz",
		}

		for hoverRE, want := range tcs {
			got, _ := env.Hover(env.RegexpSearch("go.work", hoverRE))
			if got.Value != want {
				t.Errorf(`hover on %q: got %q, want %q`, hoverRE, got, want)
			}
		}
	})
}

func TestExpandToGoWork(t *testing.T) {
	const workspace = `
-- moda/a/go.mod --
module a.com

require b.com v1.2.3
-- moda/a/a.go --
package a

import (
	"b.com/b"
)

func main() {
	var x int
	_ = b.Hello()
}
-- modb/go.mod --
module b.com

require example.com v1.2.3
-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
-- go.work --
go 1.17

use (
	./moda/a
	./modb
)
`
	WithOptions(
		WorkspaceFolders("moda/a"),
	).Run(t, workspace, func(t *testing.T, env *Env) {
		env.OpenFile("moda/a/a.go")
		env.Await(env.DoneWithOpen())
		loc := env.FirstDefinition(env.RegexpSearch("moda/a/a.go", "Hello"))
		file := env.Sandbox.Workdir.URIToPath(loc.URI)
		want := "modb/b/b.go"
		if !strings.HasSuffix(file, want) {
			t.Errorf("expected %s, got %v", want, file)
		}
	})
}

func TestInnerGoWork(t *testing.T) {
	// This test checks that gopls honors a go.work file defined
	// inside a go module (golang/go#63917).
	const workspace = `
-- go.mod --
module a.com

require b.com v1.2.3
-- a/go.work --
go 1.18

use (
	..
	../b
)
-- a/a.go --
package a

import "b.com/b"

var _ = b.B
-- b/go.mod --
module b.com/b

-- b/b.go --
package b

const B = 0
`
	WithOptions(
		// This doesn't work if we open the outer module. I'm not sure it should,
		// since the go.work file does not apply to the entire module, just a
		// subdirectory.
		WorkspaceFolders("a"),
	).Run(t, workspace, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		loc := env.FirstDefinition(env.RegexpSearch("a/a.go", "b.(B)"))
		got := env.Sandbox.Workdir.URIToPath(loc.URI)
		want := "b/b.go"
		if got != want {
			t.Errorf("Definition(b.B): got %q, want %q", got, want)
		}
	})
}

func TestNonWorkspaceFileCreation(t *testing.T) {
	const files = `
-- work/go.mod --
module mod.com

go 1.12
-- work/x.go --
package x
`

	const code = `
package foo
import "fmt"
var _ = fmt.Printf
`
	WithOptions(
		WorkspaceFolders("work"), // so that outside/... is outside the workspace
	).Run(t, files, func(t *testing.T, env *Env) {
		env.CreateBuffer("outside/foo.go", "")
		env.EditBuffer("outside/foo.go", fake.NewEdit(0, 0, 0, 0, code))
		env.FirstDefinition(env.RegexpSearch("outside/foo.go", `Printf`))
	})
}

func TestGoWork_V2Module(t *testing.T) {
	// When using a go.work, we must have proxy content even if it is replaced.
	const proxy = `
-- b.com/v2@v2.1.9/go.mod --
module b.com/v2

go 1.12
-- b.com/v2@v2.1.9/b/b.go --
package b

func Ciao()() int {
	return 0
}
`

	const multiModule = `
-- go.work --
go 1.18

use (
	moda/a
	modb
	modb/v2
	modc
)
-- moda/a/go.mod --
module a.com

require b.com/v2 v2.1.9
-- moda/a/a.go --
package a

import (
	"b.com/v2/b"
)

func main() {
	var x int
	_ = b.Hi()
}
-- modb/go.mod --
module b.com

-- modb/b/b.go --
package b

func Hello() int {
	var x int
}
-- modb/v2/go.mod --
module b.com/v2

-- modb/v2/b/b.go --
package b

func Hi() int {
	var x int
}
-- modc/go.mod --
module gopkg.in/yaml.v1 // test gopkg.in versions
-- modc/main.go --
package main

func main() {
	var x int
}
`

	WithOptions(
		ProxyFiles(proxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			// TODO(rfindley): assert on the full set of diagnostics here. We
			// should ensure that we don't have a diagnostic at b.Hi in a.go.
			Diagnostics(env.AtRegexp("moda/a/a.go", "x")),
			Diagnostics(env.AtRegexp("modb/b/b.go", "x")),
			Diagnostics(env.AtRegexp("modb/v2/b/b.go", "x")),
			Diagnostics(env.AtRegexp("modc/main.go", "x")),
		)
	})
}

// Confirm that a fix for a tidy module will correct all modules in the
// workspace.
func TestMultiModule_OneBrokenModule(t *testing.T) {
	// In the earlier 'experimental workspace mode', gopls would aggregate go.sum
	// entries for the workspace module, allowing it to correctly associate
	// missing go.sum with diagnostics. With go.work files, this doesn't work:
	// the go.command will happily write go.work.sum.
	t.Skip("golang/go#57509: go.mod diagnostics do not work in go.work mode")
	const files = `
-- go.work --
go 1.18

use (
	a
	b
)
-- go.work.sum --
-- a/go.mod --
module a.com

go 1.12
-- a/main.go --
package main
-- b/go.mod --
module b.com

go 1.12

require (
	example.com v1.2.3
)
-- b/go.sum --
-- b/main.go --
package b

import "example.com/blah"

func main() {
	blah.Hello()
}
`
	WithOptions(
		ProxyFiles(workspaceProxy),
	).Run(t, files, func(t *testing.T, env *Env) {
		params := &protocol.PublishDiagnosticsParams{}
		env.OpenFile("b/go.mod")
		env.AfterChange(
			Diagnostics(
				env.AtRegexp("go.mod", `example.com v1.2.3`),
				WithMessage("go.sum is out of sync"),
			),
			ReadDiagnostics("b/go.mod", params),
		)
		for _, d := range params.Diagnostics {
			if !strings.Contains(d.Message, "go.sum is out of sync") {
				continue
			}
			actions := env.GetQuickFixes("b/go.mod", []protocol.Diagnostic{d})
			if len(actions) != 2 {
				t.Fatalf("expected 2 code actions, got %v", len(actions))
			}
			env.ApplyQuickFixes("b/go.mod", []protocol.Diagnostic{d})
		}
		env.AfterChange(
			NoDiagnostics(ForFile("b/go.mod")),
		)
	})
}

// Tests the fix for golang/go#52500.
func TestChangeTestVariant_Issue52500(t *testing.T) {
	const src = `
-- go.mod --
module mod.test

go 1.12
-- main_test.go --
package main_test

type Server struct{}

const MainConst = otherConst
-- other_test.go --
package main_test

const otherConst = 0

func (Server) Foo() {}
`

	Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("other_test.go")
		env.RegexpReplace("other_test.go", "main_test", "main")

		// For this test to function, it is necessary to wait on both of the
		// expectations below: the bug is that when switching the package name in
		// other_test.go from main->main_test, metadata for main_test is not marked
		// as invalid. So we need to wait for the metadata of main_test.go to be
		// updated before moving other_test.go back to the main_test package.
		env.Await(
			Diagnostics(env.AtRegexp("other_test.go", "Server")),
			Diagnostics(env.AtRegexp("main_test.go", "otherConst")),
		)
		env.RegexpReplace("other_test.go", "main", "main_test")
		env.AfterChange(
			NoDiagnostics(ForFile("other_test.go")),
			NoDiagnostics(ForFile("main_test.go")),
		)

		// This will cause a test failure if other_test.go is not in any package.
		_ = env.FirstDefinition(env.RegexpSearch("other_test.go", "Server"))
	})
}

// Test for golang/go#48929.
func TestClearNonWorkspaceDiagnostics(t *testing.T) {
	const ws = `
-- go.work --
go 1.18

use (
        ./b
)
-- a/go.mod --
module a

go 1.17
-- a/main.go --
package main

func main() {
   var V string
}
-- b/go.mod --
module b

go 1.17
-- b/main.go --
package b

import (
        _ "fmt"
)
`
	Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("b/main.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/main.go")),
		)
		env.OpenFile("a/main.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/main.go", "V"), WithMessage("not used")),
		)
		// Here, diagnostics are added because of zero-config gopls.
		// In the past, they were added simply due to diagnosing changed files.
		// (see TestClearNonWorkspaceDiagnostics_NoView below for a
		// reimplementation of that test).
		if got, want := len(env.Views()), 2; got != want {
			t.Errorf("after opening a/main.go, got %d views, want %d", got, want)
		}
		env.CloseBuffer("a/main.go")
		env.AfterChange(
			NoDiagnostics(ForFile("a/main.go")),
		)
		if got, want := len(env.Views()), 1; got != want {
			t.Errorf("after closing a/main.go, got %d views, want %d", got, want)
		}
	})
}

// This test is like TestClearNonWorkspaceDiagnostics, but bypasses the
// zero-config algorithm by opening a nested workspace folder.
//
// We should still compute diagnostics correctly for open packages.
func TestClearNonWorkspaceDiagnostics_NoView(t *testing.T) {
	const ws = `
-- a/go.mod --
module example.com/a

go 1.18

require example.com/b v1.2.3

replace example.com/b => ../b

-- a/a.go --
package a

import "example.com/b"

func _() {
	V := b.B // unused
}

-- b/go.mod --
module b

go 1.18

-- b/b.go --
package b

const B = 2

func _() {
	var V int // unused
}

-- b/b2.go --
package b

const B2 = B

-- c/c.go --
package main

func main() {
	var V int // unused
}
`
	WithOptions(
		WorkspaceFolders("a"),
	).Run(t, ws, func(t *testing.T, env *Env) {
		env.OpenFile("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("b/b.go")),
			NoDiagnostics(ForFile("c/c.go")),
		)
		env.OpenFile("b/b.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			Diagnostics(env.AtRegexp("b/b.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("c/c.go")),
		)

		// Opening b/b.go should not result in a new view, because b is not
		// contained in a workspace folder.
		//
		// Yet we should get diagnostics for b, because it is open.
		if got, want := len(env.Views()), 1; got != want {
			t.Errorf("after opening b/b.go, got %d views, want %d", got, want)
		}
		env.CloseBuffer("b/b.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("b/b.go")),
			NoDiagnostics(ForFile("c/c.go")),
		)

		// We should get references in the b package.
		bUse := env.RegexpSearch("a/a.go", `b\.(B)`)
		refs := env.References(bUse)
		wantRefs := []string{"a/a.go", "b/b.go", "b/b2.go"}
		var gotRefs []string
		for _, ref := range refs {
			gotRefs = append(gotRefs, env.Sandbox.Workdir.URIToPath(ref.URI))
		}
		sort.Strings(gotRefs)
		if diff := cmp.Diff(wantRefs, gotRefs); diff != "" {
			t.Errorf("references(b.B) mismatch (-want +got)\n%s", diff)
		}

		// Opening c/c.go should also not result in a new view, yet we should get
		// orphaned file diagnostics.
		env.OpenFile("c/c.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("b/b.go")),
			Diagnostics(env.AtRegexp("c/c.go", "V"), WithMessage("not used")),
		)
		if got, want := len(env.Views()), 1; got != want {
			t.Errorf("after opening b/b.go, got %d views, want %d", got, want)
		}

		env.CloseBuffer("c/c.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("b/b.go")),
			NoDiagnostics(ForFile("c/c.go")),
		)
		env.CloseBuffer("a/a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("a/a.go", "V"), WithMessage("not used")),
			NoDiagnostics(ForFile("b/b.go")),
			NoDiagnostics(ForFile("c/c.go")),
		)
	})
}

// Test that we don't get a version warning when the Go version in PATH is
// supported.
func TestOldGoNotification_SupportedVersion(t *testing.T) {
	v := goVersion(t)
	if v < goversion.OldestSupported() {
		t.Skipf("go version 1.%d is unsupported", v)
	}

	Run(t, "", func(t *testing.T, env *Env) {
		env.OnceMet(
			InitialWorkspaceLoad,
			NoShownMessage("upgrade"),
		)
	})
}

// Test that we do get a version warning when the Go version in PATH is
// unsupported, though this test may never execute if we stop running CI at
// legacy Go versions (see also TestOldGoNotification_Fake)
func TestOldGoNotification_UnsupportedVersion(t *testing.T) {
	v := goVersion(t)
	if v >= goversion.OldestSupported() {
		t.Skipf("go version 1.%d is supported", v)
	}

	Run(t, "", func(t *testing.T, env *Env) {
		env.Await(
			// Note: cannot use OnceMet(InitialWorkspaceLoad, ...) here, as the
			// upgrade message may race with the IWL.
			ShownMessage("Please upgrade"),
		)
	})
}

func TestOldGoNotification_Fake(t *testing.T) {
	// Get the Go version from path, and make sure it's unsupported.
	//
	// In the future we'll stop running CI on legacy Go versions. By mutating the
	// oldest supported Go version here, we can at least ensure that the
	// ShowMessage pop-up works.
	ctx := context.Background()
	version, err := gocommand.GoVersion(ctx, gocommand.Invocation{}, &gocommand.Runner{})
	if err != nil {
		t.Fatal(err)
	}
	defer func(t []goversion.Support) {
		goversion.Supported = t
	}(goversion.Supported)
	goversion.Supported = []goversion.Support{
		{GoVersion: version, InstallGoplsVersion: "v1.0.0"},
	}

	Run(t, "", func(t *testing.T, env *Env) {
		env.Await(
			// Note: cannot use OnceMet(InitialWorkspaceLoad, ...) here, as the
			// upgrade message may race with the IWL.
			ShownMessage("Please upgrade"),
		)
	})
}

// goVersion returns the version of the Go command in PATH.
func goVersion(t *testing.T) int {
	t.Helper()
	ctx := context.Background()
	goversion, err := gocommand.GoVersion(ctx, gocommand.Invocation{}, &gocommand.Runner{})
	if err != nil {
		t.Fatal(err)
	}
	return goversion
}

func TestGoworkMutation(t *testing.T) {
	WithOptions(
		ProxyFiles(workspaceModuleProxy),
	).Run(t, multiModule, func(t *testing.T, env *Env) {
		env.RunGoCommand("work", "init")
		env.RunGoCommand("work", "use", "-r", ".")
		env.AfterChange(
			Diagnostics(env.AtRegexp("moda/a/a.go", "x")),
			Diagnostics(env.AtRegexp("modb/b/b.go", "x")),
			NoDiagnostics(env.AtRegexp("moda/a/a.go", `b\.Hello`)),
		)
		env.RunGoCommand("work", "edit", "-dropuse", "modb")
		env.Await(
			Diagnostics(env.AtRegexp("moda/a/a.go", "x")),
			NoDiagnostics(env.AtRegexp("modb/b/b.go", "x")),
			Diagnostics(env.AtRegexp("moda/a/a.go", `b\.Hello`)),
		)
	})
}

func TestInitializeWithNonFileWorkspaceFolders(t *testing.T) {
	for _, tt := range []struct {
		name          string
		folders       []string
		wantViewRoots []string
	}{
		{
			name:          "real,virtual",
			folders:       []string{"modb", "virtual:///virtualpath"},
			wantViewRoots: []string{"./modb"},
		},
		{
			name:          "virtual,real",
			folders:       []string{"virtual:///virtualpath", "modb"},
			wantViewRoots: []string{"./modb"},
		},
		{
			name:          "real,virtual,real",
			folders:       []string{"moda/a", "virtual:///virtualpath", "modb"},
			wantViewRoots: []string{"./moda/a", "./modb"},
		},
		{
			name:          "virtual",
			folders:       []string{"virtual:///virtualpath"},
			wantViewRoots: nil,
		},
	} {

		t.Run(tt.name, func(t *testing.T) {
			opts := []RunOption{ProxyFiles(workspaceProxy), WorkspaceFolders(tt.folders...)}
			WithOptions(opts...).Run(t, multiModule, func(t *testing.T, env *Env) {
				summary := func(typ cache.ViewType, root, folder string) command.View {
					return command.View{
						Type:   typ.String(),
						Root:   env.Sandbox.Workdir.URI(root),
						Folder: env.Sandbox.Workdir.URI(folder),
					}
				}
				checkViews := func(want ...command.View) {
					got := env.Views()
					if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(command.View{}, "ID")); diff != "" {
						t.Errorf("SummarizeViews() mismatch (-want +got):\n%s", diff)
					}
				}
				var wantViews []command.View
				for _, root := range tt.wantViewRoots {
					wantViews = append(wantViews, summary(cache.GoModView, root, root))
				}
				env.Await(
					LogMatching(protocol.Warning, "skip adding virtual folder", 1, false),
				)
				checkViews(wantViews...)
			})
		})
	}
}

// TestChangeAddedWorkspaceFolders tests issue71967 which an editor sends the following requests.
//
//  1. send an initialization request with rootURI but no workspaceFolders,
//     which gopls helps to find a workspaceFolders for it.
//  2. send a DidChangeWorkspaceFolders request with the exact the same folder gopls helps to find.
//
// It uses the same approach to simulate the scenario, and ensure we can skip the already added file.
func TestChangeAddedWorkspaceFolders(t *testing.T) {
	for _, tt := range []struct {
		name          string
		after         []string
		wantViewRoots []string
	}{
		{
			name:          "add an already added file",
			after:         []string{"modb"},
			wantViewRoots: []string{"./modb"},
		},
		{
			name:          "add an already added file but with an ending slash",
			after:         []string{"modb/"},
			wantViewRoots: []string{"./modb"},
		},
		{
			name:          "add an already added file and a new file",
			after:         []string{"modb", "moda/a"},
			wantViewRoots: []string{"./modb", "moda/a"},
		},
	} {
		t.Run(tt.name, func(t *testing.T) {
			opts := []RunOption{ProxyFiles(workspaceProxy), RootPath("modb"), NoDefaultWorkspaceFiles()}
			WithOptions(opts...).Run(t, multiModule, func(t *testing.T, env *Env) {
				summary := func(typ cache.ViewType, root, folder string) command.View {
					return command.View{
						Type:   typ.String(),
						Root:   env.Sandbox.Workdir.URI(root),
						Folder: env.Sandbox.Workdir.URI(folder),
					}
				}
				checkViews := func(want ...command.View) {
					got := env.Views()
					if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(command.View{}, "ID")); diff != "" {
						t.Errorf("SummarizeViews() mismatch (-want +got):\n%s", diff)
					}
				}
				var wantViews []command.View
				for _, root := range tt.wantViewRoots {
					wantViews = append(wantViews, summary(cache.GoModView, root, root))
				}
				env.ChangeWorkspaceFolders(tt.after...)
				env.Await(
					LogMatching(protocol.Warning, "skip adding the already added folder", 1, false),
					NoOutstandingWork(IgnoreTelemetryPromptWork),
				)
				checkViews(wantViews...)
			})
		})
	}
}

// Test that non-file scheme Document URIs in ChangeWorkspaceFolders
// notification does not produce errors.
func TestChangeNonFileWorkspaceFolders(t *testing.T) {
	for _, tt := range []struct {
		name          string
		before        []string
		after         []string
		wantViewRoots []string
	}{
		{
			name:          "add",
			before:        []string{"modb"},
			after:         []string{"modb", "moda/a", "virtual:///virtualpath"},
			wantViewRoots: []string{"./modb", "moda/a"},
		},
		{
			name:          "remove",
			before:        []string{"modb", "virtual:///virtualpath", "moda/a"},
			after:         []string{"modb"},
			wantViewRoots: []string{"./modb"},
		},
	} {
		t.Run(tt.name, func(t *testing.T) {
			opts := []RunOption{ProxyFiles(workspaceProxy), WorkspaceFolders(tt.before...)}
			WithOptions(opts...).Run(t, multiModule, func(t *testing.T, env *Env) {
				summary := func(typ cache.ViewType, root, folder string) command.View {
					return command.View{
						Type:   typ.String(),
						Root:   env.Sandbox.Workdir.URI(root),
						Folder: env.Sandbox.Workdir.URI(folder),
					}
				}
				checkViews := func(want ...command.View) {
					got := env.Views()
					if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(command.View{}, "ID")); diff != "" {
						t.Errorf("SummarizeViews() mismatch (-want +got):\n%s", diff)
					}
				}
				var wantViews []command.View
				for _, root := range tt.wantViewRoots {
					wantViews = append(wantViews, summary(cache.GoModView, root, root))
				}
				env.ChangeWorkspaceFolders(tt.after...)
				env.Await(
					LogMatching(protocol.Warning, "skip adding virtual folder", 1, false),
					NoOutstandingWork(IgnoreTelemetryPromptWork),
				)
				checkViews(wantViews...)
			})
		})
	}
}


================================================
FILE: gopls/internal/test/integration/workspace/zero_config_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package workspace

import (
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/protocol/command"

	. "golang.org/x/tools/gopls/internal/test/integration"
)

func TestAddAndRemoveGoWork(t *testing.T) {
	// Use a workspace with a module in the root directory to exercise the case
	// where a go.work is added to the existing root directory. This verifies
	// that we're detecting changes to the module source, not just the root
	// directory.
	const nomod = `
-- go.mod --
module a.com

go 1.16
-- main.go --
package main

func main() {}
-- b/go.mod --
module b.com

go 1.16
-- b/main.go --
package main

func main() {}
`
	WithOptions(
		Modes(Default),
	).Run(t, nomod, func(t *testing.T, env *Env) {
		env.OpenFile("main.go")
		env.OpenFile("b/main.go")

		summary := func(typ cache.ViewType, root, folder string) command.View {
			return command.View{
				Type:   typ.String(),
				Root:   env.Sandbox.Workdir.URI(root),
				Folder: env.Sandbox.Workdir.URI(folder),
			}
		}
		checkViews := func(want ...command.View) {
			got := env.Views()
			if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(command.View{}, "ID")); diff != "" {
				t.Errorf("SummarizeViews() mismatch (-want +got):\n%s", diff)
			}
		}

		// Zero-config gopls makes this work.
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
			NoDiagnostics(env.AtRegexp("b/main.go", "package (main)")),
		)
		checkViews(summary(cache.GoModView, ".", "."), summary(cache.GoModView, "b", "."))

		env.WriteWorkspaceFile("go.work", `go 1.16

use (
	.
	b
)
`)
		env.AfterChange(NoDiagnostics())
		checkViews(summary(cache.GoWorkView, ".", "."))

		// Removing the go.work file should put us back where we started.
		env.RemoveWorkspaceFile("go.work")

		// Again, zero-config gopls makes this work.
		env.AfterChange(
			NoDiagnostics(ForFile("main.go")),
			NoDiagnostics(env.AtRegexp("b/main.go", "package (main)")),
		)
		checkViews(summary(cache.GoModView, ".", "."), summary(cache.GoModView, "b", "."))

		// Close and reopen b, to ensure the views are adjusted accordingly.
		env.CloseBuffer("b/main.go")
		env.AfterChange()
		checkViews(summary(cache.GoModView, ".", "."))

		env.OpenFile("b/main.go")
		env.AfterChange()
		checkViews(summary(cache.GoModView, ".", "."), summary(cache.GoModView, "b", "."))
	})
}

func TestOpenAndClosePorts(t *testing.T) {
	// This test checks that as we open and close files requiring a different
	// port, the set of Views is adjusted accordingly.
	const files = `
-- go.mod --
module a.com/a

go 1.20

-- a_linux.go --
package a

-- a_darwin.go --
package a

-- a_windows.go --
package a
`

	WithOptions(
		EnvVars{
			"GOOS": "linux", // assume that linux is the default GOOS
		},
	).Run(t, files, func(t *testing.T, env *Env) {
		summary := func(envOverlay ...string) command.View {
			return command.View{
				Type:       cache.GoModView.String(),
				Root:       env.Sandbox.Workdir.URI("."),
				Folder:     env.Sandbox.Workdir.URI("."),
				EnvOverlay: envOverlay,
			}
		}
		checkViews := func(want ...command.View) {
			got := env.Views()
			if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(command.View{}, "ID")); diff != "" {
				t.Errorf("SummarizeViews() mismatch (-want +got):\n%s", diff)
			}
		}
		checkViews(summary())
		env.OpenFile("a_linux.go")
		checkViews(summary())
		env.OpenFile("a_darwin.go")
		checkViews(
			summary(),
			summary("GOARCH=amd64", "GOOS=darwin"),
		)
		env.OpenFile("a_windows.go")
		checkViews(
			summary(),
			summary("GOARCH=amd64", "GOOS=darwin"),
			summary("GOARCH=amd64", "GOOS=windows"),
		)
		env.CloseBuffer("a_darwin.go")
		checkViews(
			summary(),
			summary("GOARCH=amd64", "GOOS=windows"),
		)
		env.CloseBuffer("a_linux.go")
		checkViews(
			summary(),
			summary("GOARCH=amd64", "GOOS=windows"),
		)
		env.CloseBuffer("a_windows.go")
		checkViews(summary())
	})
}

func TestCriticalErrorsInOrphanedFiles(t *testing.T) {
	// This test checks that as we open and close files requiring a different
	// port, the set of Views is adjusted accordingly.
	const files = `
-- go.mod --
modul golang.org/lsptests/broken

go 1.20

-- a.go --
package broken

const C = 0
`

	Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(
			Diagnostics(env.AtRegexp("go.mod", "modul")),
			Diagnostics(env.AtRegexp("a.go", "broken"), WithMessage("initialization failed")),
		)
	})
}

func TestGoModReplace(t *testing.T) {
	// This test checks that we treat locally replaced modules as workspace
	// modules, according to the "includeReplaceInWorkspace" setting.
	const files = `
-- moda/go.mod --
module golang.org/a

require golang.org/b v1.2.3

replace golang.org/b => ../modb

go 1.20

-- moda/a.go --
package a

import "golang.org/b"

const A = b.B

-- modb/go.mod --
module golang.org/b

go 1.20

-- modb/b.go --
package b

const B = 1
`

	for useReplace, expectation := range map[bool]Expectation{
		true:  FileWatchMatching("modb"),
		false: NoFileWatchMatching("modb"),
	} {
		WithOptions(
			WorkspaceFolders("moda"),
			Settings{
				"includeReplaceInWorkspace": useReplace,
			},
		).Run(t, files, func(t *testing.T, env *Env) {
			env.OnceMet(
				InitialWorkspaceLoad,
				expectation,
			)
		})
	}
}

func TestDisableZeroConfig(t *testing.T) {
	// This test checks that we treat locally replaced modules as workspace
	// modules, according to the "includeReplaceInWorkspace" setting.
	const files = `
-- moda/go.mod --
module golang.org/a

go 1.20

-- moda/a.go --
package a

-- modb/go.mod --
module golang.org/b

go 1.20

-- modb/b.go --
package b

`

	WithOptions(
		Settings{"zeroConfig": false},
	).Run(t, files, func(t *testing.T, env *Env) {
		env.OpenFile("moda/a.go")
		env.OpenFile("modb/b.go")
		env.AfterChange()
		if got := env.Views(); len(got) != 1 || got[0].Type != cache.AdHocView.String() {
			t.Errorf("Views: got %v, want one adhoc view", got)
		}
	})
}

func TestVendorExcluded(t *testing.T) {
	// Test that we don't create Views for vendored modules.
	//
	// We construct the vendor directory manually here, as `go mod vendor` will
	// omit the go.mod file. This synthesizes the setup of Kubernetes, where the
	// entire module is vendored through a symlinked directory.
	const src = `
-- go.mod --
module example.com/a

go 1.18

require other.com/b v1.0.0

-- a.go --
package a
import "other.com/b"
var _ b.B

-- vendor/modules.txt --
# other.com/b v1.0.0
## explicit; go 1.14
other.com/b

-- vendor/other.com/b/go.mod --
module other.com/b
go 1.14

-- vendor/other.com/b/b.go --
package b
type B int

func _() {
	var V int // unused
}
`
	WithOptions(
		Modes(Default),
	).Run(t, src, func(t *testing.T, env *Env) {
		env.OpenFile("a.go")
		env.AfterChange(NoDiagnostics())
		loc := env.FirstDefinition(env.RegexpSearch("a.go", `b\.(B)`))
		if !strings.Contains(string(loc.URI), "/vendor/") {
			t.Fatalf("Definition(b.B) = %v, want vendored location", loc.URI)
		}
		env.OpenFile(env.Sandbox.Workdir.URIToPath(loc.URI))
		env.AfterChange(
			Diagnostics(env.AtRegexp("vendor/other.com/b/b.go", "V"), WithMessage("not used")),
		)

		if views := env.Views(); len(views) != 1 {
			t.Errorf("After opening /vendor/, got %d views, want 1. Views:\n%v", len(views), views)
		}
	})
}


================================================
FILE: gopls/internal/test/integration/wrappers.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package integration

import (
	"errors"
	"os"
	"path"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/protocol/command"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/internal/xcontext"
)

// RemoveWorkspaceFile deletes a file on disk but does nothing in the
// editor. It calls t.Fatal on any error.
func (e *Env) RemoveWorkspaceFile(name string) {
	e.TB.Helper()
	if err := e.Sandbox.Workdir.RemoveFile(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// ReadWorkspaceFile reads a file from the workspace, calling t.Fatal on any
// error.
func (e *Env) ReadWorkspaceFile(name string) string {
	e.TB.Helper()
	content, err := e.Sandbox.Workdir.ReadFile(name)
	if err != nil {
		e.TB.Fatal(err)
	}
	return string(content)
}

// WriteWorkspaceFile writes a file to disk but does nothing in the editor.
// It calls t.Fatal on any error.
func (e *Env) WriteWorkspaceFile(name, content string) {
	e.TB.Helper()
	if err := e.Sandbox.Workdir.WriteFile(e.Ctx, name, content); err != nil {
		e.TB.Fatal(err)
	}
}

// WriteWorkspaceFiles deletes a file on disk but does nothing in the
// editor. It calls t.Fatal on any error.
func (e *Env) WriteWorkspaceFiles(files map[string]string) {
	e.TB.Helper()
	if err := e.Sandbox.Workdir.WriteFiles(e.Ctx, files); err != nil {
		e.TB.Fatal(err)
	}
}

// ListFiles lists relative paths to files in the given directory.
// It calls t.Fatal on any error.
func (e *Env) ListFiles(dir string) []string {
	e.TB.Helper()
	paths, err := e.Sandbox.Workdir.ListFiles(dir)
	if err != nil {
		e.TB.Fatal(err)
	}
	return paths
}

// OpenFile opens a file in the editor, calling t.Fatal on any error.
func (e *Env) OpenFile(name string) {
	e.TB.Helper()
	if err := e.Editor.OpenFile(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// CreateBuffer creates a buffer in the editor, calling t.Fatal on any error.
func (e *Env) CreateBuffer(name string, content string) {
	e.TB.Helper()
	if err := e.Editor.CreateBuffer(e.Ctx, name, content); err != nil {
		e.TB.Fatal(err)
	}
}

// BufferText returns the current buffer contents for the file with the given
// relative path, calling t.Fatal if the file is not open in a buffer.
func (e *Env) BufferText(name string) string {
	e.TB.Helper()
	text, ok := e.Editor.BufferText(name)
	if !ok {
		e.TB.Fatalf("buffer %q is not open", name)
	}
	return text
}

// CloseBuffer closes an editor buffer without saving, calling t.Fatal on any
// error.
func (e *Env) CloseBuffer(name string) {
	e.TB.Helper()
	if err := e.Editor.CloseBuffer(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// EditBuffer applies edits to an editor buffer, calling t.Fatal on any error.
func (e *Env) EditBuffer(name string, edits ...protocol.TextEdit) {
	e.TB.Helper()
	if err := e.Editor.EditBuffer(e.Ctx, name, edits); err != nil {
		e.TB.Fatal(err)
	}
}

func (e *Env) SetBufferContent(name string, content string) {
	e.TB.Helper()
	if err := e.Editor.SetBufferContent(e.Ctx, name, content); err != nil {
		e.TB.Fatal(err)
	}
}

// FileContent returns the file content for name that applies to the current
// editing session: it returns the buffer content for an open file, the
// on-disk content for an unopened file, or "" for a non-existent file.
func (e *Env) FileContent(name string) string {
	e.TB.Helper()
	text, ok := e.Editor.BufferText(name)
	if ok {
		return text
	}
	content, err := e.Sandbox.Workdir.ReadFile(name)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			return ""
		} else {
			e.TB.Fatal(err)
		}
	}
	return string(content)
}

// FileContentAt returns the file content at the given location, using the
// file's mapper.
func (e *Env) FileContentAt(location protocol.Location) string {
	e.TB.Helper()
	mapper, err := e.Editor.Mapper(location.URI.Path())
	if err != nil {
		e.TB.Fatal(err)
	}
	start, end, err := mapper.RangeOffsets(location.Range)
	if err != nil {
		e.TB.Fatal(err)
	}
	return string(mapper.Content[start:end])
}

// RegexpSearch returns the starting position of the first match for re in the
// buffer specified by name, calling t.Fatal on any error. It first searches
// for the position in open buffers, then in workspace files.
func (e *Env) RegexpSearch(name, re string) protocol.Location {
	e.TB.Helper()
	loc, err := e.Editor.RegexpSearch(name, re)
	if err == fake.ErrUnknownBuffer {
		loc, err = e.Sandbox.Workdir.RegexpSearch(name, re)
	}
	if err != nil {
		e.TB.Fatalf("RegexpSearch: %v, %v for %q", name, err, re)
	}
	return loc
}

// RegexpReplace replaces the first group in the first match of regexpStr with
// the replace text, calling t.Fatal on any error.
func (e *Env) RegexpReplace(name, regexpStr, replace string) {
	e.TB.Helper()
	if err := e.Editor.RegexpReplace(e.Ctx, name, regexpStr, replace); err != nil {
		e.TB.Fatalf("RegexpReplace: %v", err)
	}
}

// SaveBuffer saves an editor buffer, calling t.Fatal on any error.
func (e *Env) SaveBuffer(name string) {
	e.TB.Helper()
	if err := e.Editor.SaveBuffer(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

func (e *Env) SaveBufferWithoutActions(name string) {
	e.TB.Helper()
	if err := e.Editor.SaveBufferWithoutActions(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// FirstDefinition returns the first definition of the symbol at the
// selected location, calling t.Fatal on error.
func (e *Env) FirstDefinition(loc protocol.Location) protocol.Location {
	e.TB.Helper()
	locs, err := e.Editor.Definitions(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	if len(locs) == 0 {
		e.TB.Fatalf("no definitions")
	}
	return locs[0]
}

// FirstTypeDefinition returns the first type definition of the symbol
// at the selected location, calling t.Fatal on error.
func (e *Env) FirstTypeDefinition(loc protocol.Location) protocol.Location {
	e.TB.Helper()
	locs, err := e.Editor.TypeDefinitions(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	if len(locs) == 0 {
		e.TB.Fatalf("no type definitions")
	}
	return locs[0]
}

// FormatBuffer formats the editor buffer, calling t.Fatal on any error.
func (e *Env) FormatBuffer(name string) {
	e.TB.Helper()
	if err := e.Editor.FormatBuffer(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// OrganizeImports processes the source.organizeImports codeAction, calling
// t.Fatal on any error.
func (e *Env) OrganizeImports(name string) {
	e.TB.Helper()
	if err := e.Editor.OrganizeImports(e.Ctx, name); err != nil {
		e.TB.Fatal(err)
	}
}

// ApplyQuickFixes processes the quickfix codeAction, calling t.Fatal on any error.
func (e *Env) ApplyQuickFixes(path string, diagnostics []protocol.Diagnostic) {
	e.TB.Helper()
	loc := e.Sandbox.Workdir.EntireFile(path)
	if err := e.Editor.ApplyQuickFixes(e.Ctx, loc, diagnostics); err != nil {
		e.TB.Fatal(err)
	}
}

// ApplyCodeAction applies the given code action, calling t.Fatal on any error.
func (e *Env) ApplyCodeAction(action protocol.CodeAction) {
	e.TB.Helper()
	if err := e.Editor.ApplyCodeAction(e.Ctx, action); err != nil {
		e.TB.Fatal(err)
	}
}

// Diagnostics returns diagnostics for the given file, calling t.Fatal on any
// error.
func (e *Env) Diagnostics(name string) []protocol.Diagnostic {
	e.TB.Helper()
	diags, err := e.Editor.Diagnostics(e.Ctx, name)
	if err != nil {
		e.TB.Fatal(err)
	}
	return diags
}

// GetQuickFixes returns the available quick fix code actions, calling t.Fatal
// on any error.
func (e *Env) GetQuickFixes(path string, diagnostics []protocol.Diagnostic) []protocol.CodeAction {
	e.TB.Helper()
	loc := e.Sandbox.Workdir.EntireFile(path)
	actions, err := e.Editor.GetQuickFixes(e.Ctx, loc, diagnostics)
	if err != nil {
		e.TB.Fatal(err)
	}
	return actions
}

// Hover in the editor, calling t.Fatal on any error.
// It may return (nil, zero) even on success.
func (e *Env) Hover(loc protocol.Location) (*protocol.MarkupContent, protocol.Location) {
	e.TB.Helper()
	c, loc, err := e.Editor.Hover(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return c, loc
}

func (e *Env) DocumentLink(name string) []protocol.DocumentLink {
	e.TB.Helper()
	links, err := e.Editor.DocumentLink(e.Ctx, name)
	if err != nil {
		e.TB.Fatal(err)
	}
	return links
}

func (e *Env) DocumentHighlight(loc protocol.Location) []protocol.DocumentHighlight {
	e.TB.Helper()
	highlights, err := e.Editor.DocumentHighlight(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return highlights
}

// RunGenerate runs "go generate" in the given dir, calling t.Fatal on any error.
// It waits for the generate command to complete and checks for file changes
// before returning.
func (e *Env) RunGenerate(dir string) {
	e.TB.Helper()
	if err := e.Editor.RunGenerate(e.Ctx, dir); err != nil {
		e.TB.Fatal(err)
	}
	e.Await(NoOutstandingWork(IgnoreTelemetryPromptWork))
	// Ideally the editor.Workspace would handle all synthetic file watching, but
	// we help it out here as we need to wait for the generate command to
	// complete before checking the filesystem.
	e.CheckForFileChanges()
}

// RunGoCommand runs the given command in the sandbox's default working
// directory.
func (e *Env) RunGoCommand(verb string, args ...string) []byte {
	e.TB.Helper()
	out, err := e.Sandbox.RunGoCommand(e.Ctx, "", verb, args, nil, true)
	if err != nil {
		e.TB.Fatal(err)
	}
	return out
}

// RunGoCommandInDir is like RunGoCommand, but executes in the given
// relative directory of the sandbox.
func (e *Env) RunGoCommandInDir(dir, verb string, args ...string) {
	e.TB.Helper()
	if _, err := e.Sandbox.RunGoCommand(e.Ctx, dir, verb, args, nil, true); err != nil {
		e.TB.Fatal(err)
	}
}

// RunGoCommandInDirWithEnv is like RunGoCommand, but executes in the given
// relative directory of the sandbox with the given additional environment variables.
func (e *Env) RunGoCommandInDirWithEnv(dir string, env []string, verb string, args ...string) {
	e.TB.Helper()
	if _, err := e.Sandbox.RunGoCommand(e.Ctx, dir, verb, args, env, true); err != nil {
		e.TB.Fatal(err)
	}
}

// GoVersion checks the version of the go command.
// It returns the X in Go 1.X.
func (e *Env) GoVersion() int {
	e.TB.Helper()
	v, err := e.Sandbox.GoVersion(e.Ctx)
	if err != nil {
		e.TB.Fatal(err)
	}
	return v
}

// DumpGoSum prints the correct go.sum contents for dir in txtar format,
// for use in creating integration tests.
func (e *Env) DumpGoSum(dir string) {
	e.TB.Helper()

	if _, err := e.Sandbox.RunGoCommand(e.Ctx, dir, "list", []string{"-mod=mod", "./..."}, nil, true); err != nil {
		e.TB.Fatal(err)
	}
	sumFile := path.Join(dir, "go.sum")
	e.TB.Log("\n\n-- " + sumFile + " --\n" + e.ReadWorkspaceFile(sumFile))
	e.TB.Fatal("see contents above")
}

// CheckForFileChanges triggers a manual poll of the workspace for any file
// changes since creation, or since last polling. It is a workaround for the
// lack of true file watching support in the fake workspace.
func (e *Env) CheckForFileChanges() {
	e.TB.Helper()
	if err := e.Sandbox.Workdir.CheckForFileChanges(e.Ctx); err != nil {
		e.TB.Fatal(err)
	}
}

// CodeLens calls textDocument/codeLens for the given path, calling t.Fatal on
// any error.
func (e *Env) CodeLens(path string) []protocol.CodeLens {
	e.TB.Helper()
	lens, err := e.Editor.CodeLens(e.Ctx, path)
	if err != nil {
		e.TB.Fatal(err)
	}
	return lens
}

// ExecuteCodeLensCommand executes the command for the code lens matching the
// given command name.
//
// result is a pointer to a variable to be populated by json.Unmarshal.
func (e *Env) ExecuteCodeLensCommand(path string, cmd command.Command, result any) {
	e.TB.Helper()
	if err := e.Editor.ExecuteCodeLensCommand(e.Ctx, path, cmd, result); err != nil {
		e.TB.Fatal(err)
	}
}

// ExecuteCommand executes the requested command in the editor, calling t.Fatal
// on any error.
//
// result is a pointer to a variable to be populated by json.Unmarshal.
func (e *Env) ExecuteCommand(params *protocol.ExecuteCommandParams, result any) {
	e.TB.Helper()
	if err := e.Editor.ExecuteCommand(e.Ctx, params, result); err != nil {
		e.TB.Fatal(err)
	}
}

// Views returns the server's views.
func (e *Env) Views() []command.View {
	var summaries []command.View
	cmd := command.NewViewsCommand("")
	e.ExecuteCommand(&protocol.ExecuteCommandParams{
		Command:   cmd.Command,
		Arguments: cmd.Arguments,
	}, &summaries)
	return summaries
}

// StartProfile starts a CPU profile with the given name, using the
// gopls.start_profile custom command. It calls t.Fatal on any error.
//
// The resulting stop function must be called to stop profiling (using the
// gopls.stop_profile custom command).
func (e *Env) StartProfile() (stop func() string) {
	// TODO(golang/go#61217): revisit the ergonomics of these command APIs.
	//
	// This would be a lot simpler if we generated params constructors.
	args, err := command.MarshalArgs(command.StartProfileArgs{})
	if err != nil {
		e.TB.Fatal(err)
	}
	params := &protocol.ExecuteCommandParams{
		Command:   command.StartProfile.String(),
		Arguments: args,
	}
	var result command.StartProfileResult
	e.ExecuteCommand(params, &result)

	return func() string {
		stopArgs, err := command.MarshalArgs(command.StopProfileArgs{})
		if err != nil {
			e.TB.Fatal(err)
		}
		stopParams := &protocol.ExecuteCommandParams{
			Command:   command.StopProfile.String(),
			Arguments: stopArgs,
		}
		var result command.StopProfileResult
		e.ExecuteCommand(stopParams, &result)
		return result.File
	}
}

// InlayHints calls textDocument/inlayHints for the given path, calling t.Fatal on
// any error.
func (e *Env) InlayHints(path string) []protocol.InlayHint {
	e.TB.Helper()
	hints, err := e.Editor.InlayHint(e.Ctx, path)
	if err != nil {
		e.TB.Fatal(err)
	}
	return hints
}

// Symbol calls workspace/symbol
func (e *Env) Symbol(query string) []protocol.SymbolInformation {
	e.TB.Helper()
	ans, err := e.Editor.Symbols(e.Ctx, query)
	if err != nil {
		e.TB.Fatal(err)
	}
	return ans
}

// References wraps Editor.References, calling t.Fatal on any error.
func (e *Env) References(loc protocol.Location) []protocol.Location {
	e.TB.Helper()
	locations, err := e.Editor.References(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return locations
}

// Rename wraps Editor.Rename, calling t.Fatal on any error.
func (e *Env) Rename(loc protocol.Location, newName string) {
	e.TB.Helper()
	if err := e.Editor.Rename(e.Ctx, loc, newName); err != nil {
		e.TB.Fatal(err)
	}
}

// Implementations wraps Editor.Implementations, calling t.Fatal on any error.
func (e *Env) Implementations(loc protocol.Location) []protocol.Location {
	e.TB.Helper()
	locations, err := e.Editor.Implementations(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return locations
}

// RenameFile wraps Editor.RenameFile, calling t.Fatal on any error.
func (e *Env) RenameFile(oldPath, newPath string) {
	e.TB.Helper()
	if err := e.Editor.RenameFile(e.Ctx, oldPath, newPath); err != nil {
		e.TB.Fatal(err)
	}
}

// SignatureHelp wraps Editor.SignatureHelp, calling t.Fatal on error
func (e *Env) SignatureHelp(loc protocol.Location) *protocol.SignatureHelp {
	e.TB.Helper()
	sighelp, err := e.Editor.SignatureHelp(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return sighelp
}

// Completion executes a completion request on the server.
func (e *Env) Completion(loc protocol.Location) *protocol.CompletionList {
	e.TB.Helper()
	completions, err := e.Editor.Completion(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return completions
}

func (e *Env) DidCreateFiles(files ...protocol.DocumentURI) {
	e.TB.Helper()
	err := e.Editor.DidCreateFiles(e.Ctx, files...)
	if err != nil {
		e.TB.Fatal(err)
	}
}

func (e *Env) SetSuggestionInsertReplaceMode(useReplaceMode bool) {
	e.TB.Helper()
	e.Editor.SetSuggestionInsertReplaceMode(e.Ctx, useReplaceMode)
}

// AcceptCompletion accepts a completion for the given item at the given
// position.
func (e *Env) AcceptCompletion(loc protocol.Location, item protocol.CompletionItem) {
	e.TB.Helper()
	if err := e.Editor.AcceptCompletion(e.Ctx, loc, item); err != nil {
		e.TB.Fatal(err)
	}
}

// CodeActionForFile calls textDocument/codeAction for the entire
// file, and calls t.Fatal if there were errors.
func (e *Env) CodeActionForFile(path string, diagnostics []protocol.Diagnostic) []protocol.CodeAction {
	return e.CodeAction(e.Sandbox.Workdir.EntireFile(path), diagnostics, protocol.CodeActionUnknownTrigger)
}

// CodeAction calls textDocument/codeAction for a selection,
// and calls t.Fatal if there were errors.
func (e *Env) CodeAction(loc protocol.Location, diagnostics []protocol.Diagnostic, trigger protocol.CodeActionTriggerKind) []protocol.CodeAction {
	e.TB.Helper()
	actions, err := e.Editor.CodeAction(e.Ctx, loc, diagnostics, trigger)
	if err != nil {
		e.TB.Fatal(err)
	}
	return actions
}

// ChangeConfiguration updates the editor config, calling t.Fatal on any error.
func (e *Env) ChangeConfiguration(newConfig fake.EditorConfig) {
	e.TB.Helper()
	if err := e.Editor.ChangeConfiguration(e.Ctx, newConfig); err != nil {
		e.TB.Fatal(err)
	}
}

// ChangeWorkspaceFolders updates the editor workspace folders, calling t.Fatal
// on any error.
func (e *Env) ChangeWorkspaceFolders(newFolders ...string) {
	e.TB.Helper()
	if err := e.Editor.ChangeWorkspaceFolders(e.Ctx, newFolders); err != nil {
		e.TB.Fatal(err)
	}
}

// SemanticTokensFull invokes textDocument/semanticTokens/full, calling t.Fatal
// on any error.
func (e *Env) SemanticTokensFull(path string) []fake.SemanticToken {
	e.TB.Helper()
	toks, err := e.Editor.SemanticTokensFull(e.Ctx, path)
	if err != nil {
		e.TB.Fatal(err)
	}
	return toks
}

// SemanticTokensRange invokes textDocument/semanticTokens/range, calling t.Fatal
// on any error.
func (e *Env) SemanticTokensRange(loc protocol.Location) []fake.SemanticToken {
	e.TB.Helper()
	toks, err := e.Editor.SemanticTokensRange(e.Ctx, loc)
	if err != nil {
		e.TB.Fatal(err)
	}
	return toks
}

// Close shuts down resources associated with the environment, calling t.Error
// on any error.
func (e *Env) Close() {
	ctx := xcontext.Detach(e.Ctx)
	if e.MCPSession != nil {
		if err := e.MCPSession.Close(); err != nil {
			e.TB.Errorf("closing MCP session: %v", err)
		}
	}
	if e.MCPServer != nil {
		e.MCPServer.Close()
	}
	if err := e.Editor.Close(ctx); err != nil {
		e.TB.Errorf("closing editor: %v", err)
	}
	if err := e.Sandbox.Close(); err != nil {
		e.TB.Errorf("cleaning up sandbox: %v", err)
	}
}


================================================
FILE: gopls/internal/test/marker/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package marker defines a framework for running "marker" tests, each
defined by a file in the testdata subdirectory.

Use this command to run the tests, from the gopls module:

	$ go test ./internal/test/marker [-update]

A marker test uses the '//@' syntax of the x/tools/internal/expect package to
annotate source code with various information such as locations and arguments
of LSP operations to be executed by the test. The syntax following '@' is
parsed as a comma-separated list of Go-like function calls, which we refer to
as 'markers' (or sometimes 'marks'), for example

	//@ foo(a, "b", 3), bar(0)

Unlike ordinary Go, the marker syntax also supports optional named arguments
using the syntax name=value. If provided, named arguments must appear after all
positional arguments, though their ordering with respect to other named
arguments does not matter. For example

	//@ foo(a, "b", d=4, c=3)

Each marker causes a corresponding function to be called in the test. Some
markers are declarations; for example, @loc declares a name for a source
location. Others have effects, such as executing an LSP operation and asserting
that it behaved as expected. See the Marker types documentation below for the
list of all supported markers.

Each call argument is converted to the type of the corresponding parameter of
the designated function. The conversion logic may use the surrounding context,
such as the position or nearby text. See the Argument conversion section below
for the full set of special conversions. As a special case, the blank
identifier '_' is treated as the zero value of the parameter type.

The test runner collects test cases by searching the given directory for
files with the .txt extension. Each file is interpreted as a txtar archive,
which is extracted to a temporary directory. The relative path to the .txt
file is used as the subtest name. The preliminary section of the file
(before the first archive entry) is a free-form comment.

# Special files

There are several types of file within the test archive that are given special
treatment by the test runner:

  - "skip": the presence of this file causes the test to be skipped, with
    its content used as the skip message.

  - "flags": this file is treated as a whitespace-separated list of flags
    that configure the MarkerTest instance. Supported flags:

    -{min,max}_go=go1.20 sets the {min,max}imum Go runtime version for the test
    (inclusive).
    -{min,max}_go_command=go1.20 sets the {min,max}imum Go command version for
    the test (inclusive).
    -cgo requires that CGO_ENABLED is set and the cgo tool is available.
    -write_sumfile=a,b,c instructs the test runner to generate go.sum files
    in these directories before running the test.
    -skip_goos=a,b,c instructs the test runner to skip the test for the
    listed GOOS values.
    -skip_goarch=a,b,c does the same for GOARCH.
    TODO(rfindley): using build constraint expressions for -skip_go{os,arch} would
    be clearer.
    -ignore_extra_diags suppresses errors for unmatched diagnostics
    -filter_builtins=false disables the filtering of builtins from
    completion results.
    -filter_keywords=false disables the filtering of keywords from
    completion results.
    -errors_ok=true suppresses errors for Error level log entries.

    TODO(rfindley): support flag values containing whitespace.

  - "settings.json": this file is parsed as JSON, and used as the
    session configuration (see gopls/doc/settings.md)

  - "capabilities.json": this file is parsed as JSON client capabilities,
    and applied as an overlay over the default editor client capabilities.
    see https://microsoft.github.io/language-server-protocol/specifications/lsp/3.17/specification/#clientCapabilities
    for more details.

  - "env": this file is parsed as a list of VAR=VALUE fields specifying the
    editor environment.

  - Golden files: Within the archive, file names starting with '@' are
    treated as "golden" content, and are not written to disk, but instead are
    made available to test methods expecting an argument of type *Golden,
    using the identifier following '@'. For example, if the first parameter of
    Foo were of type *Golden, the test runner would convert the identifier a
    in the call @foo(a, "b", 3) into a *Golden by collecting golden file
    data starting with "@a/". As a special case, for tests that only need one
    golden file, the data contained in the file "@a" is indexed in the *Golden
    value by the empty string "".

  - proxy files: any file starting with proxy/ is treated as a Go proxy
    file. If present, these files are written to a separate temporary
    directory and GOPROXY is set to file://<proxy directory>.

# Marker types

Markers are of two kinds: "value markers" and "action markers". Value markers
are processed in a first pass, and define named values that may be referred to
as arguments to action markers. For example, the @loc marker defines a named
location that may be used wherever a location is expected. Value markers cannot
refer to names defined by other value markers. Action markers are processed in
a second pass and perform some action such as testing an LSP operation.

Below, we list supported markers using function signatures, augmented with the
named argument support name=value, as described above. The types referred to in
the signatures below are described in the Argument conversion section.

Here is the list of supported value markers:

  - loc(name, location): specifies the name for a location in the source. These
    locations may be referenced by other markers. Naturally, the location
    argument may be specified only as a string or regular expression in the
    first pass.
    The predeclared locations BUILTIN and UNSAFE match any location in the
    GOROOT/src/{builtin/builtin,unsafe/unsafe}.go file, regardless of GOROOT.

  - defloc(name, location): performs a textDocument/definition request at the
    src location, and binds the result to the given name. This may be used to
    refer to positions in the standard library.

  - hiloc(name, location, kind): defines a documentHighlight value of the
    given location and kind. Use its label in a @highlightall marker to
    indicate the expected result of a highlight query.

  - item(name, details, kind): defines a completionItem with the provided
    fields. This information is not positional, and therefore @item markers
    may occur anywhere in the source. Use in conjunction with @complete,
    @snippet, or @rank.

    TODO(rfindley): rethink whether floating @item annotations are the best
    way to specify completion results.

Here is the list of supported action markers:

  - acceptcompletion(location, label, golden): specifies that accepting the
    completion candidate produced at the given location with provided label
    results in the given golden state.

  - codeaction(start location, kind string, diag=regexp, end=location, action=golden, edit=golden, result=golden, err=stringMatcher)

    Specifies a code action to request at the location, with given kind.
    If diag is set, the code action must be associated with the given
    diagnostic.
    If end is set, the location is defined to be between start.Start and
    end.End.

    Exactly one of action, edit, result, or err must be set:
    If action is set, it is a golden reference to a JSON blob representing the
    resolved code action, which is not applied.
    If edit is set, it is a golden reference to the edits resulting from the
    code action.
    If result is set, it is a golden reference to the full set of changed files
    resulting from the code action.
    If err is set, it is expected to match the error resulting from applying
    the code action.

  - codelens(location, title): specifies that a codelens is expected at the
    given location, with given title. Must be used in conjunction with
    @codelenses.

  - codelenses(): specifies that textDocument/codeLens should be run for the
    current document, with results compared to the @codelens annotations in
    the current document.

  - complete(location, ...items): specifies expected completion results at
    the given location. Must be used in conjunction with @item.

  - diag(location, regexp, exact=bool): specifies an expected diagnostic
    matching the given regexp at the given location. The test runner requires a
    1:1 correspondence between observed diagnostics and diag annotations. The
    diagnostics source and kind fields are ignored, to reduce fuss.

    The specified location must match the start position of the diagnostic,
    but end positions are ignored unless exact=true.

    TODO(adonovan): in the older marker framework, the annotation asserted two
    additional fields (source="compiler", kind="error"). Restore them using
    optional named arguments.

  - def(src, want ...location): performs a textDocument/definition request at
    the src location, and checks that the resulting set of locations matches want.

  - documentLink(golden): asserts that textDocument/documentLink returns
    links as described by the golden file.

  - foldingrange(golden): performs a textDocument/foldingRange for the
    current document, and compare with the golden content, which is the
    original source annotated with numbered tags delimiting the resulting
    ranges (e.g. <1 kind="..."> ... </1>).

  - format(golden): performs a textDocument/format request for the enclosing
    file, and compare against the named golden file. If the formatting
    request succeeds, the golden file must contain the resulting formatted
    source. If the formatting request fails, the golden file must contain
    the error message.

  - highlightall(all ...documentHighlight): makes a textDocument/highlight
    request at each location in "all" and checks that the result is "all".
    In other words, given highlightall(X1, X2, ..., Xn), it checks that
    highlight(X1) = highlight(X2) = ... = highlight(Xn) = {X1, X2, ..., Xn}.
    In general, highlight sets are not equivalence classes; for asymmetric
    cases, use @highlight instead.
    Each element of "all" is the label of a @hiloc marker.

  - highlight(src location, dsts ...documentHighlight): makes a
    textDocument/highlight request at the given src location, which should
    highlight the provided dst locations and kinds.

  - hover(src, dst location, sm stringMatcher): performs a textDocument/hover
    at the src location, and checks that the result is the dst location, with
    matching hover content. Be careful to avoid self-satisfying hover markers:
    if the hover content literally includes the marker comment itself,
    it will always contain the expected string! A backslash escape may help.

  - hovererr(src, sm stringMatcher): performs a textDocument/hover at the src
    location, and checks that the error matches the given stringMatcher.

  - implementation(src location, want ...location, err=stringMatcher):
    makes a textDocument/implementation query at the src location and
    checks that the resulting set of locations matches want. If err is
    set, the implementation query must fail with the expected error.

  - incomingcalls(src location, want ...location): makes a
    callHierarchy/incomingCalls query at the src location, and checks that
    the set of call.From locations matches want.
    (These locations are the declarations of the functions enclosing
    the calls, not the calls themselves.)

  - outgoingcalls(src location, want ...location): makes a
    callHierarchy/outgoingCalls query at the src location, and checks that
    the set of call.To locations matches want.

  - preparerename(src location, placeholder string, span=location): asserts
    that a textDocument/prepareRename request at the src location has the given
    placeholder text. If present, the optional span argument is verified to be
    the span of the prepareRename result. If placeholder is "", this is treated
    as a negative assertion and prepareRename should return nil.

  - quickfix(location, regexp, golden): like diag, the location and
    regexp identify an expected diagnostic, which must have exactly one
    associated "quickfix" code action.
    This action is executed for its editing effects on the source files.
    Like rename, the golden directory contains the expected transformed files.

  - quickfixerr(location, regexp, wantError): specifies that the
    quickfix operation should fail with an error that matches the expectation.
    (Failures in the computation to offer a fix do not generally result
    in LSP errors, so this marker is not appropriate for testing them.)

  - rank(location, ...string OR completionItem): executes a
    textDocument/completion request at the given location, and verifies that
    each expected completion item occurs in the results, in the expected order.
    Items may be specified as string literal completion labels, or as
    references to a completion item created with the @item marker.
    Other unexpected completion items are allowed to occur in the results, and
    are ignored. A "!" prefix on a label asserts that the symbol is not a
    completion candidate.

  - refs(location, want ...location): executes a textDocument/references request
    at the first location and asserts that the resulting set of locations
    matches want. The first want location must be the declaration (assumedly
    unique).

  - rename(location, new, golden): specifies a renaming of the
    identifier at the specified location to the new name.
    The golden directory contains the transformed files.

  - renameerr(location, new, wantError): specifies a renaming that
    fails with an error that matches the expectation.

  - signature(location, label, active): specifies that
    signatureHelp at the given location should match the provided string, with
    the active parameter (an index) highlighted.

  - snippet(location, string OR completionItem, snippet): executes a
    textDocument/completion request at the location, and searches for a result
    with label matching that its second argument, which may be a string literal
    or a reference to a completion item created by the @item marker (in which
    case the item's label is used). It checks that the resulting snippet
    matches the provided snippet.

  - subtypes  (src location, want ...location),
    supertypes(src location, want ...location):
    execute a textDocument/prepareTypeHierarchy request at the src
    location, followed by a typeHierarchy/{sub,super}types request on
    the first response, and check that the result contains the list
    of wanted locations in order.

  - symbol(golden): makes a textDocument/documentSymbol request
    for the enclosing file, formats the response with one symbol
    per line, sorts it, and compares against the named golden file.
    Each line is of the form:

    dotted.symbol.name kind "detail" +n lines

    where the "+n lines" part indicates that the declaration spans
    several lines. The test otherwise makes no attempt to check
    location information. There is no point to using more than one
    @symbol marker in a given file.

  - token(location, tokenType, mod): makes a textDocument/semanticTokens/range
    request at the given location, and asserts that the result includes
    exactly one token with the given token type and modifier string.

  - typedef(src, want ...location, err=stringMatcher): performs a
    textDocument/typeDefinition request at the src location, and checks that the
    resulting set of locations matches want. If err is set, the type definition
    query must fail with the expected error.

  - workspacesymbol(query, golden): makes a workspace/symbol request for the
    given query, formats the response with one symbol per line, and compares
    against the named golden file. As workspace symbols are by definition a
    workspace-wide request, the location of the workspace symbol marker does
    not matter. Each line is of the form:

    location name kind

  - mcptool(name string, arg string, location=location, output=golden):
    Executes an MCP tool call using the provided tool name and args (a
    JSON-encoded value). Any string or []string values in the JSON input object
    are modified to replace the substring '$WORKDIR' with the actual working
    directory of the test. Furthermore, if 'location' is provided, it is used
    to populate the 'location' property of the JSON input with the given LSP
    source location. The test then asserts that the MCP server's response
    matches the content of the golden file identified by output. For
    portability, all filepath separators in the output are normalized to '/',
    even if they occur outside of a path context.

# Expected locations
Marker tests that compare expected sets of locations (e.g. def, refs) only check
for set equality, so the order and cardinality of locations does not matter. Of
all markers that specify expected locations, only subtypes and supertypes check
for order.

# Argument conversion

Marker arguments are first parsed by the internal/expect package, which accepts
the following tokens as defined by the Go spec:
  - string, int64, float64, and rune literals
  - true and false
  - nil
  - identifiers (type expect.Identifier)
  - regular expressions, denoted the two tokens re"abc" (type *regexp.Regexp)

These values are passed as arguments to the corresponding parameter of the
test function. Additional value conversions may occur for these argument ->
parameter type pairs:

  - string->regexp: the argument is parsed as a regular expressions.

  - string->location: the argument is converted to the location of the first
    instance of the argument in the file content starting from the beginning of
    the line containing the note. Multi-line matches are permitted, but the
    match must begin before the note.

  - regexp->location: the argument is converted to the location of the first
    match for the argument in the file content starting from the beginning of
    the line containing the note. Multi-line matches are permitted, but the
    match must begin before the note. If the regular expression contains
    exactly one subgroup, the position of the subgroup is used rather than the
    position of the submatch.

  - name->location: the argument is replaced by the named location.

  - name->Golden: the argument is used to look up golden content prefixed by
    @<argument>.

  - {string,regexp,identifier}->stringMatcher: a stringMatcher type
    specifies an expected string, either in the form of a substring
    that must be present, a regular expression that it must match, or an
    identifier (e.g. foo) such that the archive entry @foo exists and
    contains the exact expected string.
    stringMatchers are used by some markers to match positive results
    (outputs) and by other markers to match error messages.

# Example

Here is a complete example:

	This test checks hovering over constants.

	-- a.go --
	package a

	const abc = 0x2a //@hover("b", "abc", abc),hover(" =", "abc", abc)

	-- @abc --
	```go
	const abc untyped int = 42
	```

	@hover("b", "abc", abc),hover(" =", "abc", abc)

In this example, the @hover annotation tells the test runner to run the
hoverMarker function, which has parameters:

	(mark marker, src, dst protocol.Location, g *Golden).

The first argument holds the test context, including fake editor with open
files, and sandboxed directory.

Argument converters translate the "b" and "abc" arguments into locations by
interpreting each one as a substring (or as a regular expression, if of the
form re"a|b") and finding the location of its first occurrence starting on the
preceding portion of the line, and the abc identifier into a the golden content
contained in the file @abc. Then the hoverMarker method executes a
textDocument/hover LSP request at the src position, and ensures the result
spans "abc", with the markdown content from @abc. (Note that the markdown
content includes the expect annotation as the doc comment.)

The next hover on the same line asserts the same result, but initiates the
hover immediately after "abc" in the source. This tests that we find the
preceding identifier when hovering.

# Updating golden files

To update golden content in the test archive, it is easier to regenerate
content automatically rather than edit it by hand. To do this, run the
tests with the -update flag. Only tests that actually run will be updated.

In some cases, golden content will vary by Go version (for example, gopls
produces different markdown at Go versions before the 1.19 go/doc update).
By convention, the golden content in test archives should match the output
at Go tip. Each test function can normalize golden content for older Go
versions.

Note that -update does not cause missing @diag or @loc markers to be added.

# TODO

  - Rename the files .txtar.
  - Eliminate all *err markers, preferring named arguments.
  - In failed assertions, display locations using symbolic @loc names where available.
*/
package marker


================================================
FILE: gopls/internal/test/marker/marker_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package marker

// This file defines the marker test framework.
// See doc.go for extensive documentation.

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"go/token"
	"go/types"
	"io/fs"
	"log"
	"net/http/httptest"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"regexp"
	"runtime"
	"slices"
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"github.com/modelcontextprotocol/go-sdk/mcp"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/debug"
	"golang.org/x/tools/gopls/internal/lsprpc"
	internalmcp "golang.org/x/tools/gopls/internal/mcp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/test/compare"
	"golang.org/x/tools/gopls/internal/test/integration"
	"golang.org/x/tools/gopls/internal/test/integration/fake"
	"golang.org/x/tools/gopls/internal/util/bug"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/servertest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

var update = flag.Bool("update", false, "if set, update test data during marker tests")

func TestMain(m *testing.M) {
	bug.PanicOnBugs = true
	testenv.ExitIfSmallMachine()
	// Disable GOPACKAGESDRIVER, as it can cause spurious test failures.
	os.Setenv("GOPACKAGESDRIVER", "off") // ignore error
	integration.FilterToolchainPathAndGOROOT()
	os.Exit(m.Run())
}

// Test runs the marker tests from the testdata directory.
//
// See package documentation for details on how marker tests work.
//
// These tests were inspired by (and in many places copied from) a previous
// iteration of the marker tests built on top of the packagestest framework.
// Key design decisions motivating this reimplementation are as follows:
//   - The old tests had a single global session, causing interaction at a
//     distance and several awkward workarounds.
//   - The old tests could not be safely parallelized, because certain tests
//     manipulated the server options
//   - Relatedly, the old tests did not have a logic grouping of assertions into
//     a single unit, resulting in clusters of files serving clusters of
//     entangled assertions.
//   - The old tests used locations in the source as test names and as the
//     identity of golden content, meaning that a single edit could change the
//     name of an arbitrary number of subtests, and making it difficult to
//     manually edit golden content.
//   - The old tests did not hew closely to LSP concepts, resulting in, for
//     example, each marker implementation doing its own position
//     transformations, and inventing its own mechanism for configuration.
//   - The old tests had an ad-hoc session initialization process. The integration
//     test environment has had more time devoted to its initialization, and has a
//     more convenient API.
//   - The old tests lacked documentation, and often had failures that were hard
//     to understand. By starting from scratch, we can revisit these aspects.
func Test(t *testing.T) {
	if testing.Short() {
		builder := os.Getenv("GO_BUILDER_NAME")
		// Note that HasPrefix(builder, "darwin-" only matches legacy builders.
		// LUCI builder names start with x_tools-goN.NN.
		// We want to exclude solaris on both legacy and LUCI builders, as
		// it is timing out.
		if strings.HasPrefix(builder, "darwin-") || strings.Contains(builder, "solaris") {
			t.Skip("golang/go#64473: skipping with -short: this test is too slow on darwin and solaris builders")
		}
		if strings.HasSuffix(builder, "freebsd-amd64-race") {
			t.Skip("golang/go#71731: the marker tests are too slow to run on the amd64-race builder")
		}
	}
	// The marker tests must be able to run go/packages.Load.
	testenv.NeedsGoPackages(t)

	const dir = "testdata"
	tests, err := loadMarkerTests(dir)
	if err != nil {
		t.Fatal(err)
	}

	// Opt: use a shared cache.
	cache := cache.New(nil)

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()

			if test.skipReason != "" {
				t.Skip(test.skipReason)
			}
			if slices.Contains(test.skipGOOS, runtime.GOOS) {
				t.Skipf("skipping on %s due to -skip_goos", runtime.GOOS)
			}
			if slices.Contains(test.skipGOARCH, runtime.GOARCH) {
				t.Skipf("skipping on %s due to -skip_goarch", runtime.GOARCH)
			}

			// TODO(rfindley): it may be more useful to have full support for build
			// constraints.
			if test.minGoVersion != "" {
				var go1point int
				if _, err := fmt.Sscanf(test.minGoVersion, "go1.%d", &go1point); err != nil {
					t.Fatalf("parsing -min_go version: %v", err)
				}
				testenv.NeedsGo1Point(t, go1point)
			}
			if test.maxGoVersion != "" {
				// A max Go version may be useful when (e.g.) a recent go/types
				// fix makes it impossible to reproduce a certain older crash.
				var go1point int
				if _, err := fmt.Sscanf(test.maxGoVersion, "go1.%d", &go1point); err != nil {
					t.Fatalf("parsing -max_go version: %v", err)
				}
				testenv.SkipAfterGo1Point(t, go1point)
			}
			if test.minGoCommandVersion != "" {
				var go1point int
				if _, err := fmt.Sscanf(test.minGoCommandVersion, "go1.%d", &go1point); err != nil {
					t.Fatalf("parsing -min_go_command version: %v", err)
				}
				testenv.NeedsGoCommand1Point(t, go1point)
			}
			if test.maxGoCommandVersion != "" {
				var go1point int
				if _, err := fmt.Sscanf(test.maxGoCommandVersion, "go1.%d", &go1point); err != nil {
					t.Fatalf("parsing -max_go_command version: %v", err)
				}
				testenv.SkipAfterGoCommand1Point(t, go1point)
			}
			if test.cgo {
				if os.Getenv("CGO_ENABLED") == "0" {
					// NeedsTool causes the test to fail if cgo is available but disabled
					// on the current platform through the environment. I'm not sure why it
					// behaves this way, but if CGO_ENABLED=0 is set, we want to skip.
					t.Skip("skipping due to CGO_ENABLED=0")
				}
				testenv.NeedsTool(t, "cgo")
			}

			config := fake.EditorConfig{
				Settings:         test.settings,
				CapabilitiesJSON: test.capabilities,
				Env:              test.env,
			}

			if _, ok := config.Settings["diagnosticsDelay"]; !ok {
				if config.Settings == nil {
					config.Settings = make(map[string]any)
				}
				config.Settings["diagnosticsDelay"] = "10ms"
			}

			// inv: config.Settings != nil

			run := &markerTestRun{
				test:       test,
				env:        newEnv(t, cache, test.files, test.proxyFiles, test.writeGoSum, config, test.mcp),
				settings:   config.Settings,
				values:     make(map[expect.Identifier]any),
				diags:      make(map[protocol.Location][]protocol.Diagnostic),
				extraNotes: make(map[protocol.DocumentURI]map[string][]*expect.Note),
			}
			defer run.env.Close()

			// Support built-in pseudo-locations here.
			// fmtLoc coerces "got" Locations to these forms
			// so they can be compared without depending
			// on line numbers in external files.
			//
			// (We could actually define "builtin:int" etc
			// with the correct file/line/col for each
			// builtin symbol, but that doesn't seem to be
			// where the bugs are.)
			run.values["BUILTIN"] = protocol.Location{
				URI: "file:///pseudo/builtin/builtin.go",
			}
			run.values["UNSAFE"] = protocol.Location{
				URI: "file:///pseudo/unsafe/unsafe.go",
			}

			// Open all files so that we operate consistently with LSP clients, and
			// (pragmatically) so that we have a Mapper available via the fake
			// editor.
			//
			// This also allows avoiding mutating the editor state in tests.
			for file := range test.files {
				run.env.OpenFile(file)
			}

			allDiags := make(map[string][]protocol.Diagnostic)
			if run.env.Editor.ServerCapabilities().DiagnosticProvider != nil {
				for name := range test.files {
					// golang/go#53275: support pull diagnostics for go.mod and go.work
					// files.
					if strings.HasSuffix(name, ".go") {
						allDiags[name] = run.env.Diagnostics(name)
					}
				}
			} else {
				// Wait for the didOpen notifications to be processed, then collect
				// diagnostics.

				run.env.AfterChange()
				var diags map[string]*protocol.PublishDiagnosticsParams
				run.env.AfterChange(integration.ReadAllDiagnostics(&diags))
				for path, params := range diags {
					allDiags[path] = params.Diagnostics
				}
			}

			for path, diags := range allDiags {
				uri := run.env.Sandbox.Workdir.URI(path)
				for _, diag := range diags {
					loc := protocol.Location{
						URI: uri,
						Range: protocol.Range{
							Start: diag.Range.Start,
							End:   diag.Range.Start, // ignore end positions
						},
					}
					run.diags[loc] = append(run.diags[loc], diag)
				}
			}

			var markers []marker
			for _, note := range test.notes {
				mark := marker{run: run, note: note}
				if fn, ok := valueMarkerFuncs[note.Name]; ok {
					fn(mark)
				} else if _, ok := actionMarkerFuncs[note.Name]; ok {
					markers = append(markers, mark) // save for later
				} else {
					uri := mark.uri()
					if run.extraNotes[uri] == nil {
						run.extraNotes[uri] = make(map[string][]*expect.Note)
					}
					run.extraNotes[uri][note.Name] = append(run.extraNotes[uri][note.Name], note)
				}
			}

			// Invoke each remaining marker in the test.
			for _, mark := range markers {
				actionMarkerFuncs[mark.note.Name](mark)
			}

			// Any remaining (un-eliminated) diagnostics are an error.
			if !test.ignoreExtraDiags {
				for loc, diags := range run.diags {
					for _, diag := range diags {
						// Note that loc is collapsed (start==end).
						// For formatting, show the exact span.
						exactLoc := protocol.Location{
							URI:   loc.URI,
							Range: diag.Range,
						}
						t.Errorf("%s: unexpected diagnostic: %q", run.fmtLoc(exactLoc), diag.Message)
					}
				}
			}

			// TODO(rfindley): use these for whole-file marker tests.
			for uri, extras := range run.extraNotes {
				for name, extra := range extras {
					if len(extra) > 0 {
						t.Errorf("%s: %d unused %q markers", run.env.Sandbox.Workdir.URIToPath(uri), len(extra), name)
					}
				}
			}

			// Now that all markers have executed, check whether there where any
			// unexpected error logs.
			// This guards against noisiness: see golang/go#66746)
			if !test.errorsOK {
				run.env.AfterChange(integration.NoErrorLogs())
			}

			formatted, err := formatTest(test)
			if err != nil {
				t.Errorf("formatTest: %v", err)
			} else if *update {
				filename := filepath.Join(dir, test.name)
				if err := os.WriteFile(filename, formatted, 0o644); err != nil {
					t.Error(err)
				}
			} else if !t.Failed() {
				// Verify that the testdata has not changed.
				//
				// Only check this if the test hasn't already failed, otherwise we'd
				// report duplicate mismatches of golden data.
				// Otherwise, verify that formatted content matches.
				if diff := compare.NamedText("formatted", "on-disk", string(formatted), string(test.content)); diff != "" {
					// at this point, the txtar file created by the test and the expected txtar file on the
					// disk differ. The differences are irrelevant if they are only the contents
					// of files from a unified diff. These files are dependent on which diff algorithm was used,
					// so instead checkDiffs has already checked that they correctly express the difference between
					// the test input and the test output. (If the test code uses the diff that created them, then
					// they would not differ, but that diff algorithms has been replaced.)
					checkDifferences(t, test.content, formatted)
				}
			}
		})
	}

	if abs, err := filepath.Abs(dir); err == nil && t.Failed() {
		t.Logf("(Filenames are relative to %s.)", abs)
	}
}

// checkDifferences reports whether the txtars in result and disk
// differ, other than in the contents of golden files containing unified diffs
func checkDifferences(t *testing.T, result, disk []byte) {
	got := txtar.Parse(result) // the computed slice of file retains the ordering in result
	want := txtar.Parse(disk)
	for i, tf := range got.Files {
		if i >= len(want.Files) {
			t.Errorf("test failed to create file %s", tf.Name)
			continue
		}
		// if they are both golden files (name starts with @) and both unified diffs
		// (both start with @@, then the difference is insignificant)
		ff := want.Files[i]
		if strings.HasPrefix(tf.Name, "@") && strings.HasPrefix(ff.Name, "@") && tf.Name == ff.Name &&
			bytes.HasPrefix(tf.Data, []byte("@@")) && bytes.HasPrefix(ff.Data, []byte("@@")) {
			continue
		}
		if !bytes.Equal(tf.Data, ff.Data) {
			t.Errorf("%s differs, got:%q want:%q", tf.Name, tf.Data, ff.Data)
		}
	}
}

// A marker holds state for the execution of a single @marker
// annotation in the source.
type marker struct {
	run  *markerTestRun
	note *expect.Note
}

// ctx returns the mark context.
func (m marker) ctx() context.Context { return m.run.env.Ctx }

// T returns the testing.TB for this mark.
func (m marker) T() testing.TB { return m.run.env.TB }

// server returns the LSP server for the marker test run.
func (m marker) editor() *fake.Editor { return m.run.env.Editor }

// server returns the LSP server for the marker test run.
func (m marker) server() protocol.Server { return m.run.env.Editor.Server }

// uri returns the URI of the file containing the marker.
func (mark marker) uri() protocol.DocumentURI {
	return mark.run.env.Sandbox.Workdir.URI(mark.run.test.fset.File(mark.note.Pos).Name())
}

// document returns a protocol.TextDocumentIdentifier for the current file.
func (mark marker) document() protocol.TextDocumentIdentifier {
	return protocol.TextDocumentIdentifier{URI: mark.uri()}
}

// path returns the relative path to the file containing the marker.
func (mark marker) path() string {
	return mark.run.env.Sandbox.Workdir.RelPath(mark.run.test.fset.File(mark.note.Pos).Name())
}

// mapper returns a *protocol.Mapper for the current file.
func (mark marker) mapper() *protocol.Mapper {
	mapper, err := mark.editor().Mapper(mark.path())
	if err != nil {
		mark.T().Fatalf("failed to get mapper for current mark: %v", err)
	}
	return mapper
}

// errorf reports a formatted error with a prefix indicating the position of
// the marker note.
//
// It formats the error message using mark.sprintf.
func (mark marker) errorf(format string, args ...any) {
	mark.T().Helper()
	msg := mark.sprintf(format, args...)
	// TODO(adonovan): consider using fmt.Fprintf(os.Stderr)+t.Fail instead of
	// t.Errorf to avoid reporting uninteresting positions in the Go source of
	// the driver. However, this loses the order of stderr wrt "FAIL: TestFoo"
	// subtest dividers.
	mark.T().Errorf("%s: %s", mark.run.fmtPos(mark.note.Pos), msg)
}

// valueMarkerFunc returns a wrapper around a function that allows it to be
// called during the processing of value markers (e.g. @value(v, 123)) with marker
// arguments converted to function parameters. The provided function's first
// parameter must be of type 'marker', and it must return a value.
//
// Unlike action markers, which are executed for actions such as test
// assertions, value markers are all evaluated first, and each computes
// a value that is recorded by its identifier, which is the marker's first
// argument. These values may be referred to from an action marker by
// this identifier, e.g. @action(... , v, ...).
//
// For example, given a fn with signature
//
//	func(mark marker, label, details, kind string) CompletionItem
//
// The result of valueMarkerFunc can associated with @item notes, and invoked
// as follows:
//
//	//@item(FooCompletion, "Foo", "func() int", "func")
//
// The provided fn should not mutate the test environment.
func valueMarkerFunc(fn any) func(marker) {
	ftype := reflect.TypeOf(fn)
	if ftype.NumIn() == 0 || ftype.In(0) != markerType {
		panic(fmt.Sprintf("value marker function %#v must accept marker as its first argument", ftype))
	}
	if ftype.NumOut() != 1 {
		panic(fmt.Sprintf("value marker function %#v must have exactly 1 result", ftype))
	}

	return func(mark marker) {
		if len(mark.note.Args) == 0 || !is[expect.Identifier](mark.note.Args[0]) {
			mark.errorf("first argument to a value marker function must be an identifier")
			return
		}
		id := mark.note.Args[0].(expect.Identifier)
		if alt, ok := mark.run.values[id]; ok {
			mark.errorf("%s already declared as %T", id, alt)
			return
		}
		args := append([]any{mark}, mark.note.Args[1:]...)
		argValues, err := convertArgs(mark, ftype, args)
		if err != nil {
			mark.errorf("%v", err)
			return
		}
		results := reflect.ValueOf(fn).Call(argValues)
		mark.run.values[id] = results[0].Interface()
	}
}

// actionMarkerFunc returns a wrapper around a function that allows it to be
// called during the processing of action markers (e.g. @action("abc", 123))
// with marker arguments converted to function parameters. The provided
// function's first parameter must be of type 'marker', and it must not return
// any values. Any named arguments that may be used by the marker func must be
// listed in allowedNames.
//
// The provided fn should not mutate the test environment.
func actionMarkerFunc(fn any, allowedNames ...string) func(marker) {
	ftype := reflect.TypeOf(fn)
	if ftype.NumIn() == 0 || ftype.In(0) != markerType {
		panic(fmt.Sprintf("action marker function %#v must accept marker as its first argument", ftype))
	}
	if ftype.NumOut() != 0 {
		panic(fmt.Sprintf("action marker function %#v cannot have results", ftype))
	}

	var allowed map[string]bool
	if len(allowedNames) > 0 {
		allowed = make(map[string]bool)
		for _, name := range allowedNames {
			allowed[name] = true
		}
	}

	return func(mark marker) {
		for name := range mark.note.NamedArgs {
			if !allowed[name] {
				mark.errorf("unexpected named argument %q", name)
			}
		}

		args := append([]any{mark}, mark.note.Args...)
		argValues, err := convertArgs(mark, ftype, args)
		if err != nil {
			mark.errorf("%v", err)
			return
		}
		reflect.ValueOf(fn).Call(argValues)
	}
}

func convertArgs(mark marker, ftype reflect.Type, args []any) ([]reflect.Value, error) {
	var (
		argValues []reflect.Value
		pnext     int          // next param index
		p         reflect.Type // current param
	)
	for i, arg := range args {
		if i < ftype.NumIn() {
			p = ftype.In(pnext)
			pnext++
		} else if p == nil || !ftype.IsVariadic() {
			// The actual number of arguments expected by the mark varies, depending
			// on whether this is a value marker or an action marker.
			//
			// Since this error indicates a bug, probably OK to have an imprecise
			// error message here.
			return nil, fmt.Errorf("too many arguments to %s", mark.note.Name)
		}
		elemType := p
		if ftype.IsVariadic() && pnext == ftype.NumIn() {
			elemType = p.Elem()
		}
		var v reflect.Value
		if id, ok := arg.(expect.Identifier); ok && id == "_" {
			v = reflect.Zero(elemType)
		} else {
			a, err := convert(mark, arg, elemType)
			if err != nil {
				return nil, err
			}
			v = reflect.ValueOf(a)
		}
		argValues = append(argValues, v)
	}
	// Check that we have sufficient arguments. If the function is variadic, we
	// do not need arguments for the final parameter.
	if pnext < ftype.NumIn()-1 || pnext == ftype.NumIn()-1 && !ftype.IsVariadic() {
		// Same comment as above: OK to be vague here.
		return nil, fmt.Errorf("not enough arguments to %s", mark.note.Name)
	}
	return argValues, nil
}

// namedArg returns the named argument for name, or the default value.
func namedArg[T any](mark marker, name string, dflt T) T {
	if v, ok := mark.note.NamedArgs[name]; ok {
		if e, ok := v.(T); ok {
			return e
		} else {
			v, err := convert(mark, v, reflect.TypeOf(dflt))
			if err != nil {
				mark.errorf("invalid value for %q: could not convert %v (%T) to %T", name, v, v, dflt)
				return dflt
			}
			return v.(T)
		}
	}
	return dflt
}

func namedArgFunc[T any](mark marker, name string, f func(marker, any) (T, error), dflt T) T {
	if v, ok := mark.note.NamedArgs[name]; ok {
		if v2, err := f(mark, v); err == nil {
			return v2
		} else {
			mark.errorf("invalid value for %q: %v: %v", name, v, err)
		}
	}
	return dflt
}

func exactlyOneNamedArg(mark marker, names ...string) bool {
	var found []string
	for _, name := range names {
		if _, ok := mark.note.NamedArgs[name]; ok {
			found = append(found, name)
		}
	}
	if len(found) != 1 {
		mark.errorf("need exactly one of %v to be set, got %v", names, found)
		return false
	}
	return true
}

// is reports whether arg is a T.
func is[T any](arg any) bool {
	_, ok := arg.(T)
	return ok
}

// Supported value marker functions. See [valueMarkerFunc] for more details.
var valueMarkerFuncs = map[string]func(marker){
	"loc":    valueMarkerFunc(locMarker),
	"item":   valueMarkerFunc(completionItemMarker),
	"hiloc":  valueMarkerFunc(highlightLocationMarker),
	"defloc": valueMarkerFunc(defLocMarker),
}

// Supported action marker functions. See [actionMarkerFunc] for more details.
//
// See doc.go for marker documentation.
var actionMarkerFuncs = map[string]func(marker){
	"acceptcompletion": actionMarkerFunc(acceptCompletionMarker),
	"codeaction":       actionMarkerFunc(codeActionMarker, "end", "diag", "action", "result", "edit", "err"),
	"codelenses":       actionMarkerFunc(codeLensesMarker),
	"complete":         actionMarkerFunc(completeMarker),
	"def":              actionMarkerFunc(defMarker),
	"diag":             actionMarkerFunc(diagMarker, "exact"),
	"documentlink":     actionMarkerFunc(documentLinkMarker),
	"foldingrange":     actionMarkerFunc(foldingRangeMarker),
	"format":           actionMarkerFunc(formatMarker),
	"highlight":        actionMarkerFunc(highlightMarker),
	"highlightall":     actionMarkerFunc(highlightAllMarker),
	"hover":            actionMarkerFunc(hoverMarker),
	"hovererr":         actionMarkerFunc(hoverErrMarker),
	"implementation":   actionMarkerFunc(implementationMarker, "err"),
	"incomingcalls":    actionMarkerFunc(incomingCallsMarker),
	"inlayhints":       actionMarkerFunc(inlayhintsMarker),
	"outgoingcalls":    actionMarkerFunc(outgoingCallsMarker),
	"preparerename":    actionMarkerFunc(prepareRenameMarker, "span"),
	"rank":             actionMarkerFunc(rankMarker),
	"refs":             actionMarkerFunc(refsMarker),
	"rename":           actionMarkerFunc(renameMarker),
	"renameerr":        actionMarkerFunc(renameErrMarker),
	"selectionrange":   actionMarkerFunc(selectionRangeMarker),
	"signature":        actionMarkerFunc(signatureMarker),
	"snippet":          actionMarkerFunc(snippetMarker),
	"subtypes":         actionMarkerFunc(subtypesMarker),
	"supertypes":       actionMarkerFunc(supertypesMarker),
	"quickfix":         actionMarkerFunc(quickfixMarker),
	"quickfixerr":      actionMarkerFunc(quickfixErrMarker),
	"symbol":           actionMarkerFunc(symbolMarker),
	"token":            actionMarkerFunc(tokenMarker),
	"typedef":          actionMarkerFunc(typedefMarker, "err"),
	"workspacesymbol":  actionMarkerFunc(workspaceSymbolMarker),
	"mcptool":          actionMarkerFunc(mcpToolMarker, "location", "output"),
}

// markerTest holds all the test data extracted from a test txtar archive.
//
// See the documentation for RunMarkerTests for more information on the archive
// format.
type markerTest struct {
	name         string                        // relative path to the txtar file in the testdata dir
	fset         *token.FileSet                // fileset used for parsing notes
	content      []byte                        // raw test content
	archive      *txtar.Archive                // original test archive
	settings     map[string]any                // gopls settings
	capabilities []byte                        // content of capabilities.json file
	env          map[string]string             // editor environment
	proxyFiles   map[string][]byte             // proxy content
	files        map[string][]byte             // data files from the archive (excluding special files)
	notes        []*expect.Note                // extracted notes from data files
	golden       map[expect.Identifier]*Golden // extracted golden content, by identifier name

	skipReason string   // the skip reason extracted from the "skip" archive file
	flags      []string // flags extracted from the special "flags" archive file.

	// Parsed flags values. See the flag definitions below for documentation.
	minGoVersion, maxGoVersion               string // min/max version of Go runtime
	minGoCommandVersion, maxGoCommandVersion string // min/max version of ambient go command

	cgo              bool
	writeGoSum       []string
	skipGOOS         []string
	skipGOARCH       []string
	ignoreExtraDiags bool
	filterBuiltins   bool
	filterKeywords   bool
	errorsOK         bool
	mcp              bool
}

// flagSet returns the flagset used for parsing the special "flags" file in the
// test archive.
func (t *markerTest) flagSet() *flag.FlagSet {
	flags := flag.NewFlagSet(t.name, flag.ContinueOnError)
	flags.StringVar(&t.minGoVersion, "min_go", "", "if set, the minimum go1.X version required for this test")
	flags.StringVar(&t.maxGoVersion, "max_go", "", "if set, the maximum go1.X version required for this test")
	flags.StringVar(&t.minGoCommandVersion, "min_go_command", "", "if set, the minimum go1.X go command version required for this test")
	flags.StringVar(&t.maxGoCommandVersion, "max_go_command", "", "if set, the maximum go1.X go command version required for this test")
	flags.BoolVar(&t.cgo, "cgo", false, "if set, requires cgo (both the cgo tool and CGO_ENABLED=1)")
	flags.Var((*stringListValue)(&t.writeGoSum), "write_sumfile", "if set, write the sumfile for these directories")
	flags.Var((*stringListValue)(&t.skipGOOS), "skip_goos", "if set, skip this test on these GOOS values")
	flags.Var((*stringListValue)(&t.skipGOARCH), "skip_goarch", "if set, skip this test on these GOARCH values")
	flags.BoolVar(&t.ignoreExtraDiags, "ignore_extra_diags", false, "if set, suppress errors for unmatched diagnostics")
	flags.BoolVar(&t.filterBuiltins, "filter_builtins", true, "if set, filter builtins from completion results")
	flags.BoolVar(&t.filterKeywords, "filter_keywords", true, "if set, filter keywords from completion results")
	flags.BoolVar(&t.errorsOK, "errors_ok", false, "if set, Error level log messages are acceptable in this test")
	flags.BoolVar(&t.mcp, "mcp", false, "if set, enable model context protocol client and server in this test")
	return flags
}

// stringListValue implements flag.Value.
type stringListValue []string

func (l *stringListValue) Set(s string) error {
	if s != "" {
		for d := range strings.SplitSeq(s, ",") {
			*l = append(*l, strings.TrimSpace(d))
		}
	}
	return nil
}

func (l stringListValue) String() string {
	return strings.Join([]string(l), ",")
}

func (mark *marker) getGolden(id expect.Identifier) *Golden {
	t := mark.run.test
	golden, ok := t.golden[id]
	// If there was no golden content for this identifier, we must create one
	// to handle the case where -update is set: we need a place to store
	// the updated content.
	if !ok {
		golden = &Golden{id: id}

		// TODO(adonovan): the separation of markerTest (the
		// static aspects) from markerTestRun (the dynamic
		// ones) is evidently bogus because here we modify
		// markerTest during execution. Let's merge the two.
		t.golden[id] = golden
	}
	if golden.firstReference == "" {
		golden.firstReference = mark.path()
	}
	return golden
}

// Golden holds extracted golden content for a single @<name> prefix.
//
// When -update is set, golden captures the updated golden contents for later
// writing.
type Golden struct {
	id             expect.Identifier
	firstReference string            // file name first referencing this golden content
	data           map[string][]byte // key "" => @id itself
	updated        map[string][]byte
}

// Get returns golden content for the given name, which corresponds to the
// relative path following the golden prefix @<name>/. For example, to access
// the content of @foo/path/to/result.json from the Golden associated with
// @foo, name should be "path/to/result.json".
//
// If -update is set, the given update function will be called to get the
// updated golden content that should be written back to testdata.
//
// Marker functions must use this method instead of accessing data entries
// directly otherwise the -update operation will delete those entries.
//
// TODO(rfindley): rethink the logic here. We may want to separate Get and Set,
// and not delete golden content that isn't set.
func (g *Golden) Get(t testing.TB, name string, updated []byte) ([]byte, bool) {
	if existing, ok := g.updated[name]; ok {
		// Multiple tests may reference the same golden data, but if they do they
		// must agree about its expected content.
		if diff := compare.NamedText("existing", "updated", string(existing), string(updated)); diff != "" {
			t.Errorf("conflicting updates for golden data %s/%s:\n%s", g.id, name, diff)
		}
	}
	if g.updated == nil {
		g.updated = make(map[string][]byte)
	}
	g.updated[name] = updated
	if *update {
		return updated, true
	}

	res, ok := g.data[name]
	return res, ok
}

// loadMarkerTests walks the given dir looking for .txt files, which it
// interprets as a txtar archive.
//
// See the documentation for RunMarkerTests for more details on the test data
// archive.
func loadMarkerTests(dir string) ([]*markerTest, error) {
	var tests []*markerTest
	err := filepath.WalkDir(dir, func(path string, _ fs.DirEntry, err error) error {
		if strings.HasSuffix(path, ".txt") {
			content, err := os.ReadFile(path)
			if err != nil {
				return err
			}

			name := filepath.ToSlash(strings.TrimPrefix(path, dir+string(filepath.Separator)))
			test, err := loadMarkerTest(name, content)
			if err != nil {
				return fmt.Errorf("%s: %v", path, err)
			}
			tests = append(tests, test)
		}
		return err
	})
	return tests, err
}

func loadMarkerTest(name string, content []byte) (*markerTest, error) {
	archive := txtar.Parse(content)
	if len(archive.Files) == 0 {
		return nil, fmt.Errorf("txtar file has no '-- filename --' sections")
	}
	if bytes.Contains(archive.Comment, []byte("\n-- ")) {
		// This check is conservative, but the comment is only a comment.
		return nil, fmt.Errorf("ill-formed '-- filename --' header in comment")
	}
	test := &markerTest{
		name:    name,
		fset:    token.NewFileSet(),
		content: content,
		archive: archive,
		files:   make(map[string][]byte),
		golden:  make(map[expect.Identifier]*Golden),
	}
	seen := make(map[string]bool)
	for _, file := range archive.Files {
		if seen[file.Name] {
			return nil, fmt.Errorf("duplicate archive section %q", file.Name)
		}
		seen[file.Name] = true
		switch {
		case file.Name == "skip":
			reason := strings.ReplaceAll(string(file.Data), "\n", " ")
			reason = strings.TrimSpace(reason)
			test.skipReason = reason

		case file.Name == "flags":
			test.flags = strings.Fields(string(file.Data))

		case file.Name == "settings.json":
			if err := json.Unmarshal(file.Data, &test.settings); err != nil {
				return nil, err
			}

		case file.Name == "capabilities.json":
			test.capabilities = file.Data // lazily unmarshalled by the editor

		case file.Name == "env":
			test.env = make(map[string]string)
			fields := strings.Fields(string(file.Data))
			for _, field := range fields {
				key, value, ok := strings.Cut(field, "=")
				if !ok {
					return nil, fmt.Errorf("env vars must be formatted as var=value, got %q", field)
				}
				test.env[key] = value
			}

		case strings.HasPrefix(file.Name, "@"): // golden content
			idstring, name, _ := strings.Cut(file.Name[len("@"):], "/")
			id := expect.Identifier(idstring)
			// Note that a file.Name of just "@id" gives (id, name) = ("id", "").
			if _, ok := test.golden[id]; !ok {
				test.golden[id] = &Golden{
					id:   id,
					data: make(map[string][]byte),
				}
			}
			test.golden[id].data[name] = file.Data

		case strings.HasPrefix(file.Name, "proxy/"):
			name := file.Name[len("proxy/"):]
			if test.proxyFiles == nil {
				test.proxyFiles = make(map[string][]byte)
			}
			test.proxyFiles[name] = file.Data

		default: // ordinary file content
			notes, err := expect.Parse(test.fset, file.Name, file.Data)
			if err != nil {
				return nil, fmt.Errorf("parsing notes in %q: %v", file.Name, err)
			}

			// Reject common misspelling: "// @mark".
			// TODO(adonovan): permit "// @" within a string. Detect multiple spaces.
			if i := bytes.Index(file.Data, []byte("// @")); i >= 0 {
				line := 1 + bytes.Count(file.Data[:i], []byte("\n"))
				return nil, fmt.Errorf("%s:%d: unwanted space before marker (// @)", file.Name, line)
			}

			// The 'go list' command doesn't work correct with modules named
			// testdata", so don't allow it as a module name (golang/go#65406).
			// (Otherwise files within it will end up in an ad hoc
			// package, "command-line-arguments/$TMPDIR/...".)
			if filepath.Base(file.Name) == "go.mod" &&
				bytes.Contains(file.Data, []byte("module testdata")) {
				return nil, fmt.Errorf("'testdata' is not a valid module name")
			}

			test.notes = append(test.notes, notes...)
			test.files[file.Name] = file.Data
		}

		// Print a warning if we see what looks like "-- filename --"
		// without the second "--". It's not necessarily wrong,
		// but it should almost never appear in our test inputs.
		if bytes.Contains(file.Data, []byte("\n-- ")) {
			log.Printf("ill-formed '-- filename --' header in %s?", file.Name)
		}
	}

	// Parse flags after loading files, as they may have been set by the "flags" file.
	set := test.flagSet()
	if err := set.Parse(test.flags); err != nil {
		return nil, fmt.Errorf("parsing flags: %v", err)
	}
	if set.NArg() > 0 {
		return nil, fmt.Errorf("surplus arguments after flags: %q", set.Args())
	}

	return test, nil
}

// formatTest formats the test as a txtar archive.
func formatTest(test *markerTest) ([]byte, error) {
	arch := &txtar.Archive{
		Comment: test.archive.Comment,
	}

	updatedGolden := make(map[string][]byte)
	firstReferences := make(map[string]string)
	for id, g := range test.golden {
		for name, data := range g.updated {
			filename := "@" + path.Join(string(id), name) // name may be ""
			updatedGolden[filename] = data
			firstReferences[filename] = g.firstReference
		}
	}

	// Preserve the original ordering of archive files.
	for _, file := range test.archive.Files {
		switch file.Name {
		// Preserve configuration files exactly as they were. They must have parsed
		// if we got this far.
		case "skip", "flags", "settings.json", "capabilities.json", "env":
			arch.Files = append(arch.Files, file)
		default:
			if _, ok := test.files[file.Name]; ok { // ordinary file
				arch.Files = append(arch.Files, file)
			} else if strings.HasPrefix(file.Name, "proxy/") { // proxy file
				arch.Files = append(arch.Files, file)
			} else if data, ok := updatedGolden[file.Name]; ok { // golden file
				arch.Files = append(arch.Files, txtar.File{Name: file.Name, Data: data})
				delete(updatedGolden, file.Name)
			}
		}
	}

	// ...but insert new golden files after their first reference.
	var newGoldenFiles []txtar.File
	for filename, data := range updatedGolden {
		// TODO(rfindley): it looks like this implicitly removes trailing newlines
		// from golden content. Is there any way to fix that? Perhaps we should
		// just make the diff tolerant of missing newlines?
		newGoldenFiles = append(newGoldenFiles, txtar.File{Name: filename, Data: data})
	}
	// Sort new golden files lexically.
	sort.Slice(newGoldenFiles, func(i, j int) bool {
		return newGoldenFiles[i].Name < newGoldenFiles[j].Name
	})
	for _, g := range newGoldenFiles {
		insertAt := len(arch.Files)
		if firstRef := firstReferences[g.Name]; firstRef != "" {
			for i, f := range arch.Files {
				if f.Name == firstRef {
					// Insert alphabetically among golden files following the test file.
					for i++; i < len(arch.Files); i++ {
						f := arch.Files[i]
						if !strings.HasPrefix(f.Name, "@") || f.Name >= g.Name {
							insertAt = i
							break
						}
					}
					break
				}
			}
		}
		arch.Files = slices.Insert(arch.Files, insertAt, g)
	}

	return txtar.Format(arch), nil
}

// newEnv creates a new environment for a marker test.
//
// TODO(rfindley): simplify and refactor the construction of testing
// environments across integration tests, marker tests, and benchmarks.
func newEnv(t *testing.T, cache *cache.Cache, files, proxyFiles map[string][]byte, writeGoSum []string, config fake.EditorConfig, enableMCP bool) *integration.Env {
	sandbox, err := fake.NewSandbox(&fake.SandboxConfig{
		RootDir:    t.TempDir(),
		Files:      files,
		ProxyFiles: proxyFiles,
	})
	if err != nil {
		t.Fatal(err)
	}

	for _, dir := range writeGoSum {
		if _, err := sandbox.RunGoCommand(context.Background(), dir, "list", []string{"-mod=mod", "..."}, []string{"GOWORK=off"}, true); err != nil {
			t.Fatal(err)
		}
	}

	// Put a debug instance in the context to prevent logging to stderr.
	// See associated TODO in runner.go: we should revisit this pattern.
	ctx := context.Background()
	ctx = debug.WithInstance(ctx, "")

	awaiter := integration.NewAwaiter(sandbox.Workdir)

	ss := lsprpc.NewStreamServer(cache, false, nil)

	var mcpServer *httptest.Server
	if enableMCP {
		mcpServer = httptest.NewServer(internalmcp.HTTPHandler(ss, false, nil))
	}

	server := servertest.NewPipeServer(ss, jsonrpc2.NewRawStream)
	editor, err := fake.NewEditor(sandbox, config).Connect(ctx, server, awaiter.Hooks())
	if err != nil {
		sandbox.Close() // ignore error
		t.Fatal(err)
	}

	if err := awaiter.Await(ctx, integration.OnceMet(
		integration.InitialWorkspaceLoad,
		integration.NoShownMessage(""),
	)); err != nil {
		sandbox.Close() // ignore error
		t.Fatal(err)
	}

	var mcpSession *mcp.ClientSession
	if enableMCP {
		client := mcp.NewClient(&mcp.Implementation{Name: "test", Version: "v1.0.0"}, nil)
		mcpSession, err = client.Connect(ctx, &mcp.SSEClientTransport{Endpoint: mcpServer.URL}, nil)
		if err != nil {
			t.Fatalf("fail to connect to mcp server: %v", err)
		}
	}

	return &integration.Env{
		TB:         t,
		Ctx:        ctx,
		Editor:     editor,
		Sandbox:    sandbox,
		Awaiter:    awaiter,
		MCPSession: mcpSession,
		MCPServer:  mcpServer,
	}
}

// A markerTestRun holds the state of one run of a marker test archive.
type markerTestRun struct {
	test     *markerTest
	env      *integration.Env
	settings map[string]any

	// Collected information.
	// Each @diag/@quickfix marker eliminates an entry from diags.
	values map[expect.Identifier]any
	diags  map[protocol.Location][]protocol.Diagnostic // diagnostics by position; location end == start

	// Notes that weren't associated with a top-level marker func. They may be
	// consumed by another marker (e.g. @codelenses collects @codelens markers).
	// Any notes that aren't consumed are flagged as an error.
	extraNotes map[protocol.DocumentURI]map[string][]*expect.Note
}

// sprintf returns a formatted string after applying pre-processing to
// arguments of the following types:
//   - token.Pos: formatted using (*markerTestRun).fmtPos
//   - protocol.Location: formatted using (*markerTestRun).fmtLoc
func (c *marker) sprintf(format string, args ...any) string {
	if false {
		_ = fmt.Sprintf(format, args...) // enable vet printf checker
	}
	var args2 []any
	for _, arg := range args {
		switch arg := arg.(type) {
		case token.Pos:
			args2 = append(args2, c.run.fmtPos(arg))
		case protocol.Location:
			args2 = append(args2, c.run.fmtLoc(arg))
		default:
			args2 = append(args2, arg)
		}
	}
	return fmt.Sprintf(format, args2...)
}

// fmtPos formats the given pos in the context of the test, using
// archive-relative paths for files and including the line number in the full
// archive file.
func (run *markerTestRun) fmtPos(pos token.Pos) string {
	file := run.test.fset.File(pos)
	if file == nil {
		run.env.TB.Errorf("position %d not in test fileset", pos)
		return "<invalid location>"
	}
	m, err := run.env.Editor.Mapper(file.Name())
	if err != nil {
		run.env.TB.Errorf("%s", err)
		return "<invalid location>"
	}
	loc, err := m.PosLocation(file, pos, pos)
	if err != nil {
		run.env.TB.Errorf("Mapper(%s).PosLocation failed: %v", file.Name(), err)
	}
	return run.fmtLoc(loc)
}

// fmtLoc formats the given location in the context of the test, using
// archive-relative paths for files and including the line number in the full
// archive file.
func (run *markerTestRun) fmtLoc(loc protocol.Location) string {
	if loc == (protocol.Location{}) {
		run.env.TB.Errorf("unable to find %s in test archive", loc)
		return "<invalid location>"
	}

	// Format builtin locations as "file:///pseudo/builtin/builtin.go:0:0",
	// which is the predefined BUILTIN marker; ditto UNSAFE.
	if strings.HasSuffix(string(loc.URI), "src/unsafe/unsafe.go") ||
		strings.HasSuffix(string(loc.URI), "src/builtin/builtin.go") {
		name := filepath.Base(filepath.Dir(loc.URI.Path())) // "unsafe" or "builtin"
		loc.URI = protocol.DocumentURI("file:///pseudo/" + name + "/" + name + ".go")
		loc.Range = protocol.Range{}
	}

	lines := bytes.Count(run.test.archive.Comment, []byte("\n"))
	var name string
	for _, f := range run.test.archive.Files {
		lines++ // -- separator --
		uri := run.env.Sandbox.Workdir.URI(f.Name)
		if uri == loc.URI {
			name = f.Name
			break
		}
		lines += bytes.Count(f.Data, []byte("\n"))
	}
	if name == "" {
		// Fall back to formatting the "lsp" location.
		// These will be in UTF-16, but we probably don't need to clarify that,
		// since it will be implied by the file:// URI format.
		return summarizeLoc(string(loc.URI),
			int(loc.Range.Start.Line), int(loc.Range.Start.Character),
			int(loc.Range.End.Line), int(loc.Range.End.Character))
	}
	name, startLine, startCol, endLine, endCol := run.mapLocation(loc)
	innerSpan := summarizeLoc(name, startLine, startCol, endLine, endCol)
	outerSpan := summarizeLoc(run.test.name, lines+startLine, startCol, lines+endLine, endCol)
	return fmt.Sprintf("%s (%s)", innerSpan, outerSpan)
}

// mapLocation returns the relative path and utf8 span of the corresponding
// location, which must be a valid location in an archive file.
func (run *markerTestRun) mapLocation(loc protocol.Location) (name string, startLine, startCol, endLine, endCol int) {
	// Note: Editor.Mapper fails if loc.URI is not open, but we always open all
	// archive files, so this is probably OK.
	//
	// In the future, we may want to have the editor read contents from disk if
	// the URI is not open.
	name = run.env.Sandbox.Workdir.URIToPath(loc.URI)
	m, err := run.env.Editor.Mapper(name)
	if err != nil {
		run.env.TB.Errorf("internal error: %v", err)
		return
	}
	start, end, err := m.RangeOffsets(loc.Range)
	if err != nil {
		run.env.TB.Errorf("error formatting location %s: %v", loc, err)
		return
	}
	startLine, startCol = m.OffsetLineCol8(start)
	endLine, endCol = m.OffsetLineCol8(end)
	return name, startLine, startCol, endLine, endCol
}

// fmtLocForGolden is like fmtLoc, but chooses more succinct and stable
// formatting, such as would be used for formatting locations in Golden
// content.
func (run *markerTestRun) fmtLocForGolden(loc protocol.Location) string {
	if loc == (protocol.Location{}) {
		return "<invalid location>"
	}
	name := run.env.Sandbox.Workdir.URIToPath(loc.URI)
	// Note: we check IsAbs on filepaths rather than the slash-ified name for
	// accurate handling of windows drive letters.
	if filepath.IsAbs(filepath.FromSlash(name)) {
		// Don't format any position information in this case, since it will be
		// volatile.
		return "<external>"
	}
	return summarizeLoc(run.mapLocation(loc))
}

// summarizeLoc formats a summary of the given location, in the form
//
//	<name>:<startLine>:<startCol>[-[<endLine>:]endCol]
func summarizeLoc(name string, startLine, startCol, endLine, endCol int) string {
	span := fmt.Sprintf("%s:%d:%d", name, startLine, startCol)
	if startLine != endLine || startCol != endCol {
		span += "-"
		if endLine != startLine {
			span += fmt.Sprintf("%d:", endLine)
		}
		span += fmt.Sprintf("%d", endCol)
	}
	return span
}

// ---- converters ----

// Types with special handling.
var (
	goldenType        = reflect.TypeFor[*Golden]()
	markerType        = reflect.TypeFor[marker]()
	stringMatcherType = reflect.TypeFor[stringMatcher]()
)

// Custom conversions.
//
// These functions are called after valueMarkerFuncs have run to convert
// arguments into the desired parameter types.
//
// Converters should return an error rather than calling marker.errorf().
var customConverters = map[reflect.Type]func(marker, any) (any, error){
	reflect.TypeFor[protocol.Location](): converter(convertLocation),
	reflect.TypeFor[completionLabel]():   converter(convertCompletionLabel),
}

// converter transforms a typed argument conversion function to an untyped
// conversion function.
func converter[T any](f func(marker, any) (T, error)) func(marker, any) (any, error) {
	return func(m marker, arg any) (any, error) {
		return f(m, arg)
	}
}

func convert(mark marker, arg any, paramType reflect.Type) (any, error) {
	// Handle stringMatcher and golden parameters before resolving identifiers,
	// because golden content lives in a separate namespace from other
	// identifiers.
	// TODO(rfindley): simplify by flattening the namespace. This interacts
	// poorly with named argument resolution.
	switch paramType {
	case stringMatcherType:
		return convertStringMatcher(mark, arg)
	case goldenType:
		id, ok := arg.(expect.Identifier)
		if !ok {
			return nil, fmt.Errorf("invalid input type %T: golden key must be an identifier", arg)
		}
		return mark.getGolden(id), nil
	}
	if id, ok := arg.(expect.Identifier); ok {
		if arg2, ok := mark.run.values[id]; ok {
			arg = arg2
		}
	}
	if converter, ok := customConverters[paramType]; ok {
		arg2, err := converter(mark, arg)
		if err != nil {
			return nil, err
		}
		arg = arg2
	}
	if reflect.TypeOf(arg).AssignableTo(paramType) {
		return arg, nil // no conversion required
	}
	return nil, fmt.Errorf("cannot convert %v (%T) to %s", arg, arg, paramType)
}

// convertNamedArgLocation is a workaround for converting locations referenced
// by a named argument. See the TODO in [convert]: this wouldn't be necessary
// if we flattened the namespace such that golden content lived in the same
// namespace as values.
func convertNamedArgLocation(mark marker, arg any) (protocol.Location, error) {
	if id, ok := arg.(expect.Identifier); ok {
		if v, ok := mark.run.values[id]; ok {
			if loc, ok := v.(protocol.Location); ok {
				return loc, nil
			}
			return protocol.Location{}, fmt.Errorf("invalid location value %v", v)
		}
	}
	return convertLocation(mark, arg)
}

// convertLocation converts a string or regexp argument into the protocol
// location corresponding to the first position of the string (or first match
// of the regexp) in the line preceding the note.
func convertLocation(mark marker, arg any) (protocol.Location, error) {
	// matchContent is used to match the given argument against the file content
	// starting at the marker line.
	var matchContent func([]byte) (int, int, error)

	switch arg := arg.(type) {
	case protocol.Location:
		return arg, nil // nothing to do
	case string:
		matchContent = func(content []byte) (int, int, error) {
			idx := bytes.Index(content, []byte(arg))
			if idx < 0 {
				return 0, 0, fmt.Errorf("substring %q not found", arg)
			}
			return idx, idx + len(arg), nil
		}
	case *regexp.Regexp:
		matchContent = func(content []byte) (int, int, error) {
			matches := arg.FindSubmatchIndex(content)
			if len(matches) == 0 {
				return 0, 0, fmt.Errorf("no match for regexp %q", arg)
			}
			switch len(matches) {
			case 2:
				// no subgroups: return the range of the regexp expression
				return matches[0], matches[1], nil
			case 4:
				// one subgroup: return its range
				return matches[2], matches[3], nil
			default:
				return 0, 0, fmt.Errorf("invalid location regexp %q: expect either 0 or 1 subgroups, got %d", arg, len(matches)/2-1)
			}
		}
	default:
		return protocol.Location{}, fmt.Errorf("cannot convert argument type %T to location (must be a string or regexp to match the preceding line)", arg)
	}

	// Now use matchFunc to match a range starting on the marker line.

	file := mark.run.test.fset.File(mark.note.Pos)
	posn := safetoken.Position(file, mark.note.Pos)
	lineStart := file.LineStart(posn.Line)
	lineStartOff, lineEndOff, err := safetoken.Offsets(file, lineStart, mark.note.Pos)
	if err != nil {
		return protocol.Location{}, err
	}
	m := mark.mapper()
	start, end, err := matchContent(m.Content[lineStartOff:])
	if err != nil {
		return protocol.Location{}, err
	}
	startOff, endOff := lineStartOff+start, lineStartOff+end
	if startOff > lineEndOff {
		// The start of the match must be between the start of the line and the
		// marker position (inclusive).
		return protocol.Location{}, fmt.Errorf("no matching range found starting on the current line")
	}
	return m.OffsetLocation(startOff, endOff)
}

// completionLabel is a special parameter type that may be converted from a
// string literal, or extracted from a completion item.
//
// See [convertCompletionLabel].
type completionLabel string

// convertCompletionLabel coerces an argument to a [completionLabel] parameter
// type.
//
// If the arg is a string, it is trivially converted. If the arg is a
// completionItem, its label is extracted.
//
// This allows us to stage a migration of the "snippet" marker to a simpler
// model where the completion label can just be listed explicitly.
func convertCompletionLabel(mark marker, arg any) (completionLabel, error) {
	switch arg := arg.(type) {
	case string:
		return completionLabel(arg), nil
	case completionItem:
		return completionLabel(arg.Label), nil
	default:
		return "", fmt.Errorf("cannot convert argument type %T to completion label (must be a string or completion item)", arg)
	}
}

// convertStringMatcher converts a string, regexp, or identifier
// argument into a stringMatcher. The string is a substring of the
// expected error, the regexp is a pattern than matches the expected
// error, and the identifier is a golden file containing the expected
// error.
func convertStringMatcher(mark marker, arg any) (stringMatcher, error) {
	switch arg := arg.(type) {
	case string:
		return stringMatcher{substr: arg}, nil
	case *regexp.Regexp:
		return stringMatcher{pattern: arg}, nil
	case expect.Identifier:
		golden := mark.getGolden(arg)
		return stringMatcher{golden: golden}, nil
	default:
		return stringMatcher{}, fmt.Errorf("cannot convert %T to wantError (want: string, regexp, or identifier)", arg)
	}
}

// A stringMatcher represents an expectation of a specific string value.
//
// It may be indicated in one of three ways, in 'expect' notation:
//   - an identifier 'foo', to compare (exactly) with the contents of the golden
//     section @foo;
//   - a pattern expression re"ab.*c", to match against a regular expression;
//   - a string literal "abc", to check for a substring.
type stringMatcher struct {
	golden  *Golden
	pattern *regexp.Regexp
	substr  string
}

// empty reports whether the receiver is an empty stringMatcher.
func (sm stringMatcher) empty() bool {
	return sm.golden == nil && sm.pattern == nil && sm.substr == ""
}

func (sm stringMatcher) String() string {
	if sm.golden != nil {
		return fmt.Sprintf("content from @%s entry", sm.golden.id)
	} else if sm.pattern != nil {
		return fmt.Sprintf("content matching %#q", sm.pattern)
	} else {
		return fmt.Sprintf("content with substring %q", sm.substr)
	}
}

// checkErr asserts that the given error matches the stringMatcher's expectations.
func (sm stringMatcher) checkErr(mark marker, err error) {
	if err == nil {
		mark.errorf("@%s succeeded unexpectedly, want %v", mark.note.Name, sm)
		return
	}
	sm.check(mark, err.Error())
}

// check asserts that the given content matches the stringMatcher's expectations.
func (sm stringMatcher) check(mark marker, got string) {
	if sm.golden != nil {
		compareGolden(mark, []byte(got), sm.golden)
	} else if sm.pattern != nil {
		// Content must match the regular expression pattern.
		if !sm.pattern.MatchString(got) {
			mark.errorf("got %q, does not match pattern %#q", got, sm.pattern)
		}
	} else if !strings.Contains(got, sm.substr) {
		// Content must contain the expected substring.
		mark.errorf("got %q, want substring %q", got, sm.substr)
	}
}

// checkChangedFiles compares the files changed by an operation with their expected (golden) state.
func checkChangedFiles(mark marker, changed map[string][]byte, golden *Golden) {
	// Check changed files match expectations.
	for filename, got := range changed {
		if want, ok := golden.Get(mark.T(), filename, got); !ok {
			mark.errorf("%s: unexpected change to file %s; got:\n%s",
				mark.note.Name, filename, got)
		} else if string(got) != string(want) {
			mark.errorf("%s: wrong file content for %s:\n-- got --\n%s\n-- want --\n%s\n-- diff --\n%s",
				mark.note.Name, filename, got, want,
				compare.Bytes(want, got))
		}
	}

	// Report unmet expectations.
	for filename := range golden.data {
		if _, ok := changed[filename]; !ok {
			want, _ := golden.Get(mark.T(), filename, nil)
			mark.errorf("%s: missing change to file %s; want:\n%s",
				mark.note.Name, filename, want)
		}
	}
}

// checkDiffs checks that the diff content stored in the given golden directory
// converts the original contents into the changed contents.
// (This logic is strange because hundreds of existing marker tests were created
// containing a modified version of unified diffs.)
func checkDiffs(mark marker, changed map[string][]byte, golden *Golden) {
	for name, after := range changed {
		before := mark.run.env.FileContent(name)
		edits := diff.Lines(before, string(after))
		d, err := diff.ToUnified("before", "after", before, edits, 0)
		if err != nil {
			// Can't happen: edits are consistent.
			log.Fatalf("internal error in diff.ToUnified: %v", err)
		}
		// Trim the unified header from diffs, as it is unnecessary and repetitive.
		// (an artifact of ToUnified, but not stored in the marker files)
		difflines := strings.Split(d, "\n")
		var got string
		if len(difflines) >= 2 && strings.HasPrefix(difflines[1], "+++") {
			got = strings.Join(difflines[2:], "\n")
		} else {
			got = d // "" in packagedecl.txt:147
		}
		// the call to Get is so that the -update flag will update the test.
		// normally it just returns 'got'.
		if tdiffs, ok := golden.Get(mark.T(), name, []byte(got)); !ok {
			mark.errorf("%s: unexpected change to file %s; got diff:\n%s",
				mark.note.Name, name, got)
			return
		} else {
			// restore the ToUnified header lines deleted above
			// before calling ApplyUnified
			diffsFromTest := "--- \n+++ \n" + string(tdiffs)
			want, err := diff.ApplyUnified(diffsFromTest, before)
			if err != nil {
				mark.errorf("%s: ApplyUnified(%q,%q) failed: %v",
					mark.note.Name, before, after, err)
			}
			if want != string(after) {
				mark.errorf("%s: got\n%q expected\n%q",
					mark.note.Name, want, string(after))
			}
		}
	}

	// Report unmet expectations.
	for filename := range golden.data {
		if _, ok := changed[filename]; !ok {
			want, _ := golden.Get(mark.T(), filename, nil)
			mark.errorf("%s: missing change to file %s; want:\n%s",
				mark.note.Name, filename, want)
		}
	}
}

// ---- marker functions ----

// TODO(rfindley): consolidate documentation of these markers. They are already
// documented above, so much of the documentation here is redundant.

// completionItem is a simplified summary of a completion item.
type completionItem struct {
	Label, Detail, Kind, Documentation string
}

func completionItemMarker(mark marker, label string, other ...string) completionItem {
	if len(other) > 3 {
		mark.errorf("too many arguments to @item: expect at most 4")
	}
	item := completionItem{
		Label: label,
	}
	if len(other) > 0 {
		item.Detail = other[0]
	}
	if len(other) > 1 {
		item.Kind = other[1]
	}
	if len(other) > 2 {
		item.Documentation = other[2]
	}
	return item
}

func rankMarker(mark marker, src protocol.Location, items ...completionLabel) {
	// Separate positive and negative items (expectations).
	var pos, neg []completionLabel
	for _, item := range items {
		if strings.HasPrefix(string(item), "!") {
			neg = append(neg, item)
		} else {
			pos = append(pos, item)
		}
	}

	// Collect results that are present in items, preserving their order.
	list := mark.run.env.Completion(src)
	var got []string
	for _, g := range list.Items {
		for _, w := range pos {
			if g.Label == string(w) {
				got = append(got, g.Label)
				break
			}
		}
		for _, w := range neg {
			if g.Label == string(w[len("!"):]) {
				mark.errorf("got unwanted completion: %s", g.Label)
				break
			}
		}
	}
	var want []string
	for _, w := range pos {
		want = append(want, string(w))
	}
	if diff := cmp.Diff(want, got); diff != "" {
		mark.errorf("completion rankings do not match (-want +got):\n%s", diff)
	}
}

func snippetMarker(mark marker, src protocol.Location, label completionLabel, want string) {
	list := mark.run.env.Completion(src)
	var (
		found bool
		got   string
		all   []string // for errors
	)
	items := filterBuiltinsAndKeywords(mark, list.Items)
	for _, i := range items {
		all = append(all, i.Label)
		if i.Label == string(label) {
			found = true
			if i.TextEdit != nil {
				if edit, err := protocol.SelectCompletionTextEdit(i, false); err == nil {
					got = edit.NewText
				}
			}
			break
		}
	}
	if !found {
		mark.errorf("no completion item found matching %s (got: %v)", label, all)
		return
	}
	if got != want {
		mark.errorf("snippets do not match: got:\n%q\nwant:\n%q", got, want)
	}
}

// completeMarker implements the @complete marker, running
// textDocument/completion at the given src location and asserting that the
// results match the expected results.
func completeMarker(mark marker, src protocol.Location, want ...completionItem) {
	list := mark.run.env.Completion(src)
	items := filterBuiltinsAndKeywords(mark, list.Items)
	var got []completionItem
	for i, item := range items {
		simplified := completionItem{
			Label:  item.Label,
			Detail: item.Detail,
			Kind:   fmt.Sprint(item.Kind),
		}
		if item.Documentation != nil {
			switch v := item.Documentation.Value.(type) {
			case string:
				simplified.Documentation = v
			case protocol.MarkupContent:
				simplified.Documentation = strings.TrimSpace(v.Value) // trim newlines
			}
		}
		// Support short-hand notation: if Detail, Kind, or Documentation are omitted from the
		// item, don't match them.
		if i < len(want) {
			if want[i].Detail == "" {
				simplified.Detail = ""
			}
			if want[i].Kind == "" {
				simplified.Kind = ""
			}
			if want[i].Documentation == "" {
				simplified.Documentation = ""
			}
		}
		got = append(got, simplified)
	}
	if len(want) == 0 {
		want = nil // got is nil if empty
	}
	if diff := cmp.Diff(want, got); diff != "" {
		mark.errorf("Completion(...) returned unexpected results (-want +got):\n%s", diff)
	}
}

// filterBuiltinsAndKeywords filters out builtins and keywords from completion
// results.
//
// It over-approximates, and does not detect if builtins are shadowed.
func filterBuiltinsAndKeywords(mark marker, items []protocol.CompletionItem) []protocol.CompletionItem {
	keep := 0
	for _, item := range items {
		if mark.run.test.filterKeywords && item.Kind == protocol.KeywordCompletion {
			continue
		}
		if mark.run.test.filterBuiltins && types.Universe.Lookup(item.Label) != nil {
			continue
		}
		items[keep] = item
		keep++
	}
	return items[:keep]
}

// acceptCompletionMarker implements the @acceptCompletion marker, running
// textDocument/completion at the given src location and accepting the
// candidate with the given label. The resulting source must match the provided
// golden content.
func acceptCompletionMarker(mark marker, src protocol.Location, label string, golden *Golden) {
	list := mark.run.env.Completion(src)
	var selected *protocol.CompletionItem
	for _, item := range list.Items {
		if item.Label == label {
			selected = &item
			break
		}
	}
	if selected == nil {
		mark.errorf("Completion(...) did not return an item labeled %q", label)
		return
	}
	edit, err := protocol.SelectCompletionTextEdit(*selected, false)
	if err != nil {
		mark.errorf("Completion(...) did not return a valid edit: %v", err)
		return
	}
	filename := mark.path()
	mapper := mark.mapper()
	patched, _, err := protocol.ApplyEdits(mapper, append([]protocol.TextEdit{edit}, selected.AdditionalTextEdits...))
	if err != nil {
		mark.errorf("ApplyProtocolEdits failed: %v", err)
		return
	}
	changes := map[string][]byte{filename: patched}
	// Check the file state.
	checkChangedFiles(mark, changes, golden)
}

// defMarker implements the @def marker, running textDocument/definition at
// the given location and asserting that there the results match want.
func defMarker(mark marker, loc protocol.Location, want ...protocol.Location) {
	env := mark.run.env
	got, err := env.Editor.Definitions(env.Ctx, loc)
	if err != nil {
		mark.errorf("definition request failed: %v", err)
		return
	}

	if err := compareLocations(mark, got, want); err != nil {
		mark.errorf("def failed: %v", err)
	}
}

// typedefMarker implements the @typedef marker.
func typedefMarker(mark marker, loc protocol.Location, want ...protocol.Location) {
	wantErr := namedArgFunc(mark, "err", convertStringMatcher, stringMatcher{})

	env := mark.run.env
	got, err := env.Editor.TypeDefinitions(env.Ctx, loc)
	if err != nil && wantErr.empty() {
		mark.errorf("typeDefinition at %s failed: %v", loc, err)
		return
	}
	if !wantErr.empty() {
		wantErr.checkErr(mark, err)
		return
	}

	if err := compareLocations(mark, got, want); err != nil {
		mark.errorf("typedef failed: %v", err)
	}
}

func foldingRangeMarker(mark marker, g *Golden) {
	env := mark.run.env
	ranges, err := mark.server().FoldingRange(env.Ctx, &protocol.FoldingRangeParams{
		TextDocument: mark.document(),
	})
	if err != nil {
		mark.errorf("foldingRange failed: %v", err)
		return
	}
	var edits []protocol.TextEdit
	insert := func(line, char uint32, text string) {
		pos := protocol.Position{Line: line, Character: char}
		edits = append(edits, protocol.TextEdit{
			Range: protocol.Range{
				Start: pos,
				End:   pos,
			},
			NewText: text,
		})
	}
	for i, rng := range ranges {
		// We assume the server populates these optional fields.
		insert(*rng.StartLine, *rng.StartCharacter, fmt.Sprintf("<%d kind=%q>", i, rng.Kind))
		insert(*rng.EndLine, *rng.EndCharacter, fmt.Sprintf("</%d>", i))
	}
	filename := mark.path()
	mapper, err := env.Editor.Mapper(filename)
	if err != nil {
		mark.errorf("Editor.Mapper(%s) failed: %v", filename, err)
		return
	}
	got, _, err := protocol.ApplyEdits(mapper, edits)
	if err != nil {
		mark.errorf("ApplyProtocolEdits failed: %v", err)
		return
	}
	want, _ := g.Get(mark.T(), "", got)
	if diff := compare.Bytes(want, got); diff != "" {
		mark.errorf("foldingRange mismatch:\n%s", diff)
	}
}

// formatMarker implements the @format marker.
func formatMarker(mark marker, golden *Golden) {
	edits, err := mark.server().Formatting(mark.ctx(), &protocol.DocumentFormattingParams{
		TextDocument: mark.document(),
	})
	var got []byte
	if err != nil {
		got = []byte(err.Error() + "\n") // all golden content is newline terminated
	} else {
		env := mark.run.env
		filename := mark.path()
		mapper, err := env.Editor.Mapper(filename)
		if err != nil {
			mark.errorf("Editor.Mapper(%s) failed: %v", filename, err)
		}

		got, _, err = protocol.ApplyEdits(mapper, edits)
		if err != nil {
			mark.errorf("ApplyProtocolEdits failed: %v", err)
			return
		}
	}

	compareGolden(mark, got, golden)
}

func highlightLocationMarker(mark marker, loc protocol.Location, kindName expect.Identifier) protocol.DocumentHighlight {
	var kind protocol.DocumentHighlightKind
	switch kindName {
	case "read":
		kind = protocol.Read
	case "write":
		kind = protocol.Write
	case "text":
		kind = protocol.Text
	default:
		mark.errorf("invalid highlight kind: %q", kindName)
	}

	return protocol.DocumentHighlight{
		Range: loc.Range,
		Kind:  kind,
	}
}

func sortDocumentHighlights(s []protocol.DocumentHighlight) {
	sort.Slice(s, func(i, j int) bool {
		return protocol.CompareRange(s[i].Range, s[j].Range) < 0
	})
}

// highlightAllMarker makes textDocument/highlight
// requests at locations of equivalence classes. Given input
// highlightall(X1, X2, ..., Xn), the marker checks
// highlight(X1) = highlight(X2) = ... = highlight(Xn) = {X1, X2, ..., Xn}.
// It is not the general rule for all highlighting, and use @highlight
// for asymmetric cases.
//
// TODO(b/288111111): this is a bit of a hack. We should probably
// have a more general way of testing that a function is idempotent.
func highlightAllMarker(mark marker, all ...protocol.DocumentHighlight) {
	sortDocumentHighlights(all)
	for _, src := range all {
		loc := mark.uri().Location(src.Range)
		got := mark.run.env.DocumentHighlight(loc)
		sortDocumentHighlights(got)

		if d := cmp.Diff(all, got); d != "" {
			mark.errorf("DocumentHighlight(%v) mismatch (-want +got):\n%s", loc, d)
		}
	}
}

func highlightMarker(mark marker, src protocol.DocumentHighlight, dsts ...protocol.DocumentHighlight) {
	loc := mark.uri().Location(src.Range)
	got := mark.run.env.DocumentHighlight(loc)

	sortDocumentHighlights(got)
	sortDocumentHighlights(dsts)

	if diff := cmp.Diff(dsts, got, cmpopts.EquateEmpty()); diff != "" {
		mark.errorf("DocumentHighlight(%v) mismatch (-want +got):\n%s", src, diff)
	}
}

func hoverMarker(mark marker, src, dst protocol.Location, sc stringMatcher) {
	content, gotDst := mark.run.env.Hover(src)
	if gotDst != dst {
		mark.errorf("hover location does not match:\n\tgot: %s\n\twant %s)", mark.run.fmtLoc(gotDst), mark.run.fmtLoc(dst))
	}
	gotMD := ""
	if content != nil {
		gotMD = content.Value

		// Normalize the absolute path for cross-platform consistency before
		// replacement. This ensures Windows paths (e.g., "C:/...") become
		// "/C:/..." to match Unix-like paths.
		abs := mark.run.env.Sandbox.Workdir.RootURI().Path()
		if protocol.IsWindowsDrivePath(abs) {
			abs = "/" + abs
		}
		gotMD = strings.ReplaceAll(gotMD, filepath.ToSlash(abs), "$WORKDIR")
	}
	sc.check(mark, gotMD)
}

func hoverErrMarker(mark marker, src protocol.Location, em stringMatcher) {
	_, _, err := mark.editor().Hover(mark.ctx(), src)
	em.checkErr(mark, err)
}

// locMarker implements the @loc marker.
func locMarker(mark marker, loc protocol.Location) protocol.Location { return loc }

// defLocMarker implements the @defloc marker, which binds a location to the
// (first) result of a jump-to-definition request.
func defLocMarker(mark marker, loc protocol.Location) protocol.Location {
	return mark.run.env.FirstDefinition(loc)
}

// diagMarker implements the @diag marker. It eliminates diagnostics from
// the observed set in mark.test.
func diagMarker(mark marker, loc protocol.Location, re *regexp.Regexp) {
	exact := namedArg(mark, "exact", false)
	if _, ok := removeDiagnostic(mark, loc, exact, re); !ok {
		mark.errorf("no diagnostic at %v matches %q", loc, re)
	}
}

// removeDiagnostic looks for a diagnostic matching loc at the given position.
//
// If found, it returns (diag, true), and eliminates the matched diagnostic
// from the unmatched set.
//
// If not found, it returns (protocol.Diagnostic{}, false).
func removeDiagnostic(mark marker, loc protocol.Location, matchEnd bool, re *regexp.Regexp) (protocol.Diagnostic, bool) {
	key := loc
	key.Range.End = key.Range.Start // diagnostics ignore end position.
	diags := mark.run.diags[key]
	for i, diag := range diags {
		if re.MatchString(diag.Message) && (!matchEnd || diag.Range.End == loc.Range.End) {
			mark.run.diags[key] = slices.Delete(diags, i, i+1)
			return diag, true
		}
	}
	return protocol.Diagnostic{}, false
}

// renameMarker implements the @rename(location, new, golden) marker.
func renameMarker(mark marker, loc protocol.Location, newName string, golden *Golden) {
	changed, err := rename(mark.run.env, loc, newName)
	if err != nil {
		mark.errorf("rename failed: %v. (Use @renameerr for expected errors.)", err)
		return
	}
	checkDiffs(mark, changed, golden)
}

// renameErrMarker implements the @renamererr(location, new, error) marker.
func renameErrMarker(mark marker, loc protocol.Location, newName string, wantErr stringMatcher) {
	_, err := rename(mark.run.env, loc, newName)
	wantErr.checkErr(mark, err)
}

func selectionRangeMarker(mark marker, loc protocol.Location, g *Golden) {
	ranges, err := mark.server().SelectionRange(mark.ctx(), &protocol.SelectionRangeParams{
		TextDocument: mark.document(),
		Positions:    []protocol.Position{loc.Range.Start},
	})
	if err != nil {
		mark.errorf("SelectionRange failed: %v", err)
		return
	}
	var buf bytes.Buffer
	m := mark.mapper()
	for i, path := range ranges {
		fmt.Fprintf(&buf, "Ranges %d:", i)
		rng := path
		for {
			s, e, err := m.RangeOffsets(rng.Range)
			if err != nil {
				mark.errorf("RangeOffsets failed: %v", err)
				return
			}

			var snippet string
			if e-s < 30 {
				snippet = string(m.Content[s:e])
			} else {
				snippet = string(m.Content[s:s+15]) + "..." + string(m.Content[e-15:e])
			}

			fmt.Fprintf(&buf, "\n\t%v %q", rng.Range, strings.ReplaceAll(snippet, "\n", "\\n"))

			if rng.Parent == nil {
				break
			}
			rng = *rng.Parent
		}
		buf.WriteRune('\n')
	}
	compareGolden(mark, buf.Bytes(), g)
}

func tokenMarker(mark marker, loc protocol.Location, tokenType, mod string) {
	tokens := mark.run.env.SemanticTokensRange(loc)
	if len(tokens) != 1 {
		mark.errorf("got %d tokens, want 1", len(tokens))
		return
	}
	tok := tokens[0]
	if tok.TokenType != tokenType {
		mark.errorf("token type = %q, want %q", tok.TokenType, tokenType)
	}
	if tok.Mod != mod {
		mark.errorf("token mod = %q, want %q", tok.Mod, mod)
	}
}

func signatureMarker(mark marker, src protocol.Location, label string, active int64) {
	got := mark.run.env.SignatureHelp(src)
	var gotLabels []string // for better error messages
	if got != nil {
		for _, s := range got.Signatures {
			gotLabels = append(gotLabels, s.Label)
		}
	}
	if label == "" {
		// A null result is expected.
		// (There's no point having a @signatureerr marker
		// because the server handler suppresses all errors.)
		if got != nil && len(gotLabels) > 0 {
			mark.errorf("signatureHelp = %v, want 0 signatures", gotLabels)
		}
		return
	}
	if got == nil || len(got.Signatures) != 1 {
		mark.errorf("signatureHelp = %v, want exactly 1 signature", gotLabels)
		return
	}
	if got := gotLabels[0]; got != label {
		mark.errorf("signatureHelp: got label %q, want %q", got, label)
	}
	gotActiveParameter := int64(-1) // => missing
	if got.ActiveParameter != nil {
		gotActiveParameter = int64(*got.ActiveParameter)
	}
	if gotActiveParameter != active {
		mark.errorf("signatureHelp: got active parameter %d, want %d", gotActiveParameter, active)
	}
}

// rename returns the new contents of the files that would be modified
// by renaming the identifier at loc to newName.
func rename(env *integration.Env, loc protocol.Location, newName string) (map[string][]byte, error) {
	// We call Server.Rename directly, instead of
	//   env.Editor.Rename(env.Ctx, loc, newName)
	// to isolate Rename from PrepareRename, and because we don't
	// want to modify the file system in a scenario with multiple
	// @rename markers.

	wsedit, err := env.Editor.Server.Rename(env.Ctx, &protocol.RenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(loc),
		NewName:                    newName,
	})
	if err != nil {
		return nil, err
	}
	return changedFiles(env, wsedit.DocumentChanges)
}

// changedFiles applies the given sequence of document changes to the
// editor buffer content, recording the final contents in the returned map.
// The actual editor state is not changed.
// Deleted files are indicated by a content of []byte(nil).
//
// See also:
//   - Editor.applyWorkspaceEdit ../integration/fake/editor.go for the
//     implementation of this operation used in normal testing.
//   - client.applyWorkspaceEdit in ../../../cmd/cmd.go for the
//     CLI variant.
func changedFiles(env *integration.Env, changes []protocol.DocumentChange) (map[string][]byte, error) {
	uriToPath := env.Sandbox.Workdir.URIToPath

	// latest maps each updated file name to a mapper holding its
	// current contents, or nil if the file has been deleted.
	latest := make(map[protocol.DocumentURI]*protocol.Mapper)

	// read reads a file. It returns an error if the file never
	// existed or was deleted.
	read := func(uri protocol.DocumentURI) (*protocol.Mapper, error) {
		if m, ok := latest[uri]; ok {
			if m == nil {
				return nil, fmt.Errorf("read: file %s was deleted", uri)
			}
			return m, nil
		}
		return env.Editor.Mapper(uriToPath(uri))
	}

	// write (over)writes a file. A nil content indicates a deletion.
	write := func(uri protocol.DocumentURI, content []byte) {
		var m *protocol.Mapper
		if content != nil {
			m = protocol.NewMapper(uri, content)
		}
		latest[uri] = m
	}

	// Process the sequence of changes.
	for _, change := range changes {
		switch {
		case change.TextDocumentEdit != nil:
			uri := change.TextDocumentEdit.TextDocument.URI
			m, err := read(uri)
			if err != nil {
				return nil, err // missing
			}
			patched, _, err := protocol.ApplyEdits(m, protocol.AsTextEdits(change.TextDocumentEdit.Edits))
			if err != nil {
				return nil, err // bad edit
			}
			write(uri, patched)

		case change.RenameFile != nil:
			old := change.RenameFile.OldURI
			new := change.RenameFile.NewURI
			info, err := os.Stat(old.Path())
			if err != nil {
				return nil, err
			}
			if info.IsDir() {
				// Walk through all the files in the old directory and copy
				// their content to the new directory.
				// TODO(mkalil): This currently only handles renaming the file's
				// innermost directory. Need to handle renames of outer directories
				// directories when implementing package move refactoring.
				for _, file := range env.ListFiles(old.Path()) {
					oldFile := protocol.URIFromPath(path.Join(old.Path(), path.Base(file)))
					m, err := read(oldFile)
					if err != nil {
						return nil, err // missing
					}
					write(oldFile, nil)

					newFile := protocol.URIFromPath(path.Join(new.Path(), path.Base(file)))
					if _, err := read(oldFile); err == nil {
						return nil, fmt.Errorf("RenameFile: destination %s exists", new)
					}
					write(newFile, m.Content)
				}
			} else {
				m, err := read(old)
				if err != nil {
					return nil, err // missing
				}
				write(old, nil)

				if _, err := read(old); err == nil {
					return nil, fmt.Errorf("RenameFile: destination %s exists", new)
				}
				write(new, m.Content)
			}

		case change.CreateFile != nil:
			uri := change.CreateFile.URI
			if _, err := read(uri); err == nil {
				return nil, fmt.Errorf("CreateFile %s: file exists", uri)
			}
			write(uri, []byte("")) // initially empty

		case change.DeleteFile != nil:
			uri := change.DeleteFile.URI
			if _, err := read(uri); err != nil {
				// The specified URI could be a file or a directory.
				files := env.ListFiles(uriToPath(uri))
				if files == nil {
					return nil, fmt.Errorf("DeleteFile %s: file does not exist", uri)
				}
				if len(files) > 0 {
					// Directory is not empty. If "Recursive" is true, we delete
					// every file in the folder. Otherwise, we continue without
					// deleting the directory.
					if change.DeleteFile.Options != nil && change.DeleteFile.Options.Recursive {
						for _, f := range files {
							write(protocol.URIFromPath(f), nil)
						}
					}
					continue
				}
			}
			write(uri, nil)

		default:
			return nil, fmt.Errorf("invalid DocumentChange")
		}
	}

	// Convert into result form.
	result := make(map[string][]byte)
	for uri, mapper := range latest {
		var content []byte
		if mapper != nil {
			content = mapper.Content
		}
		result[uriToPath(uri)] = content
	}

	return result, nil
}

func codeActionMarker(mark marker, loc protocol.Location, kind string) {
	if !exactlyOneNamedArg(mark, "action", "edit", "result", "err") {
		return
	}

	if end := namedArgFunc(mark, "end", convertNamedArgLocation, protocol.Location{}); end.URI != "" {
		if end.URI != loc.URI {
			mark.errorf("end marker is in a different file (%s)", filepath.Base(loc.URI.Path()))
			return
		}
		loc.Range.End = end.Range.End
	}

	var (
		edit       = namedArg(mark, "edit", expect.Identifier(""))
		result     = namedArg(mark, "result", expect.Identifier(""))
		wantAction = namedArg(mark, "action", expect.Identifier(""))
		wantErr    = namedArgFunc(mark, "err", convertStringMatcher, stringMatcher{})
	)

	var diag *protocol.Diagnostic
	if re := namedArg(mark, "diag", (*regexp.Regexp)(nil)); re != nil {
		d, ok := removeDiagnostic(mark, loc, false, re)
		if !ok {
			mark.errorf("no diagnostic at %v matches %q", loc, re)
			return
		}
		diag = &d
	}

	action, err := resolveCodeAction(mark.run.env, loc.URI, loc.Range, protocol.CodeActionKind(kind), diag)
	if err != nil {
		if !wantErr.empty() {
			wantErr.checkErr(mark, err)
		} else {
			mark.errorf("resolveCodeAction failed: %v", err)
		}
		return
	}

	// If when 'action' is set, we simply compare the action, and don't apply it.
	if wantAction != "" {
		g := mark.getGolden(wantAction)
		if action == nil {
			mark.errorf("no matching codeAction")
			return
		}
		data, err := json.MarshalIndent(action, "", "\t")
		if err != nil {
			mark.errorf("failed to marshal codeaction: %v", err)
			return
		}
		data = bytes.ReplaceAll(data, []byte(mark.run.env.Sandbox.Workdir.RootURI()), []byte("$WORKDIR"))
		compareGolden(mark, data, g)
		return
	}

	changes, err := applyCodeAction(mark.run.env, action)
	if err != nil {
		if !wantErr.empty() {
			wantErr.checkErr(mark, err)
		} else {
			mark.errorf("codeAction failed: %v", err)
		}
		return
	}
	changed, err := changedFiles(mark.run.env, changes)
	if err != nil {
		mark.errorf("changedFiles failed: %v", err)
		return
	}

	switch {
	case edit != "":
		g := mark.getGolden(edit)
		checkDiffs(mark, changed, g)
	case result != "":
		g := mark.getGolden(result)
		// Check the file state.
		checkChangedFiles(mark, changed, g)
	case !wantErr.empty():
		wantErr.checkErr(mark, err)
	default:
		panic("unreachable")
	}
}

// codeLensesMarker runs the @codelenses() marker, collecting @codelens marks
// in the current file and comparing with the result of the
// textDocument/codeLens RPC.
func codeLensesMarker(mark marker) {
	type codeLens struct {
		Range protocol.Range
		Title string
	}

	lenses := mark.run.env.CodeLens(mark.path())
	var got []codeLens
	for _, lens := range lenses {
		title := ""
		if lens.Command != nil {
			title = lens.Command.Title
		}
		got = append(got, codeLens{lens.Range, title})
	}

	var want []codeLens
	mark.consumeExtraNotes("codelens", actionMarkerFunc(func(_ marker, loc protocol.Location, title string) {
		want = append(want, codeLens{loc.Range, title})
	}))

	for _, s := range [][]codeLens{got, want} {
		sort.Slice(s, func(i, j int) bool {
			li, lj := s[i], s[j]
			if c := protocol.CompareRange(li.Range, lj.Range); c != 0 {
				return c < 0
			}
			return li.Title < lj.Title
		})
	}

	if diff := cmp.Diff(want, got); diff != "" {
		mark.errorf("codelenses: unexpected diff (-want +got):\n%s", diff)
	}
}

func documentLinkMarker(mark marker, g *Golden) {
	var b bytes.Buffer
	links := mark.run.env.DocumentLink(mark.path())
	for _, l := range links {
		if l.Target == nil {
			mark.errorf("%s: nil link target", l.Range)
			continue
		}
		loc := mark.uri().Location(l.Range)
		fmt.Fprintln(&b, mark.run.fmtLocForGolden(loc), *l.Target)
	}

	compareGolden(mark, b.Bytes(), g)
}

// consumeExtraNotes runs the provided func for each extra note with the given
// name, and deletes all matching notes.
func (mark marker) consumeExtraNotes(name string, f func(marker)) {
	uri := mark.uri()
	notes := mark.run.extraNotes[uri][name]
	delete(mark.run.extraNotes[uri], name)

	for _, note := range notes {
		f(marker{run: mark.run, note: note})
	}
}

// quickfixMarker implements the @quickfix(location, regexp,
// kind, golden) marker. It acts like @diag(location, regexp), to set
// the expectation of a diagnostic, but then it applies the "quickfix"
// code action (which must be unique) suggested by the matched diagnostic.
func quickfixMarker(mark marker, loc protocol.Location, re *regexp.Regexp, golden *Golden) {
	loc.Range.End = loc.Range.Start // diagnostics ignore end position.
	// Find and remove the matching diagnostic.
	diag, ok := removeDiagnostic(mark, loc, false, re)
	if !ok {
		mark.errorf("no diagnostic at %v matches %q", loc, re)
		return
	}

	// Apply the fix it suggests.
	changed, err := codeAction(mark.run.env, loc.URI, diag.Range, "quickfix", &diag)
	if err != nil {
		mark.errorf("quickfix failed: %v. (Use @quickfixerr for expected errors.)", err)
		return
	}

	// Check the file state.
	checkDiffs(mark, changed, golden)
}

func quickfixErrMarker(mark marker, loc protocol.Location, re *regexp.Regexp, wantErr stringMatcher) {
	loc.Range.End = loc.Range.Start // diagnostics ignore end position.
	// Find and remove the matching diagnostic.
	diag, ok := removeDiagnostic(mark, loc, false, re)
	if !ok {
		mark.errorf("no diagnostic at %v matches %q", loc, re)
		return
	}

	// Apply the fix it suggests.
	_, err := codeAction(mark.run.env, loc.URI, diag.Range, "quickfix", &diag)
	wantErr.checkErr(mark, err)
}

// codeAction executes a textDocument/codeAction request for the specified
// location and kind. If diag is non-nil, it is used as the code action
// context.
//
// The resulting map contains resulting file contents after the code action is
// applied. Currently, this function does not support code actions that return
// edits directly; it only supports code action commands.
func codeAction(env *integration.Env, uri protocol.DocumentURI, rng protocol.Range, kind protocol.CodeActionKind, diag *protocol.Diagnostic) (map[string][]byte, error) {
	action, err := resolveCodeAction(env, uri, rng, kind, diag)
	if err != nil {
		return nil, err
	}
	changes, err := applyCodeAction(env, action)
	if err != nil {
		return nil, err
	}
	return changedFiles(env, changes)
}

// resolveCodeAction resolves the code action specified by the given location,
// kind, and diagnostic.
func resolveCodeAction(env *integration.Env, uri protocol.DocumentURI, rng protocol.Range, kind protocol.CodeActionKind, diag *protocol.Diagnostic) (*protocol.CodeAction, error) {
	// Request all code actions that apply to the diagnostic.
	// A production client would set Only=[kind],
	// but we can give a better error if we don't filter.
	params := &protocol.CodeActionParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: uri},
		Range:        rng,
		Context: protocol.CodeActionContext{
			Only: []protocol.CodeActionKind{protocol.Empty}, // => all
		},
	}
	if diag != nil {
		params.Context.Diagnostics = []protocol.Diagnostic{*diag}
	}

	actions, err := env.Editor.Server.CodeAction(env.Ctx, params)
	if err != nil {
		return nil, err
	}

	// Find the sole candidate CodeAction of exactly the specified kind
	// (e.g. refactor.inline.call).
	var candidates []protocol.CodeAction
	for _, act := range actions {
		if act.Kind == kind {
			candidates = append(candidates, act)
		}
	}
	if len(candidates) != 1 {
		var msg bytes.Buffer
		fmt.Fprintf(&msg, "found %d CodeActions of kind %s for this diagnostic, want 1", len(candidates), kind)
		for _, act := range actions {
			fmt.Fprintf(&msg, "\n\tfound %q (%s)", act.Title, act.Kind)
		}
		return nil, errors.New(msg.String())
	}
	action := candidates[0]

	// Resolve code action edits first if the client has resolve support
	// and the code action has no edits.
	if action.Edit == nil {
		editSupport, err := env.Editor.EditResolveSupport()
		if err != nil {
			return nil, err
		}
		if editSupport {
			resolved, err := env.Editor.Server.ResolveCodeAction(env.Ctx, &action)
			if err != nil {
				return nil, err
			}
			action = *resolved
		}
	}

	return &action, nil
}

// applyCodeAction applies the given code action, and captures the resulting
// document changes.
func applyCodeAction(env *integration.Env, action *protocol.CodeAction) ([]protocol.DocumentChange, error) {
	// Collect any server-initiated changes created by workspace/applyEdit.
	//
	// We set up this handler immediately, not right before executing the code
	// action command, so we can assert that neither the codeAction request nor
	// codeAction resolve request cause edits as a side effect (golang/go#71405).
	var changes []protocol.DocumentChange
	restore := env.Editor.Client().SetApplyEditHandler(func(ctx context.Context, wsedit *protocol.WorkspaceEdit) error {
		changes = append(changes, wsedit.DocumentChanges...)
		return nil
	})
	defer restore()

	if action.Edit == nil && action.Command == nil {
		panic("bad action")
	}

	// Apply the codeAction.
	//
	// Spec:
	//  "If a code action provides an edit and a command, first the edit is
	//  executed and then the command."
	// An action may specify an edit and/or a command, to be
	// applied in that order. But since applyDocumentChanges(env,
	// action.Edit.DocumentChanges) doesn't compose, for now we
	// assert that actions return one or the other.
	if action.Edit != nil {
		if len(action.Edit.Changes) > 0 {
			env.TB.Errorf("internal error: discarding unexpected CodeAction{Kind=%s, Title=%q}.Edit.Changes", action.Kind, action.Title)
		}
		if action.Edit.DocumentChanges != nil {
			if action.Command != nil {
				env.TB.Errorf("internal error: discarding unexpected CodeAction{Kind=%s, Title=%q}.Command", action.Kind, action.Title)
			}
			return action.Edit.DocumentChanges, nil
		}
	}

	if action.Command != nil {
		// This is a typical CodeAction command:
		//
		//   Title:     "Implement error"
		//   Command:   gopls.apply_fix
		//   Arguments: [{"Fix":"stub_methods","URI":".../a.go","Range":...}}]
		//
		// The client makes an ExecuteCommand RPC to the server,
		// which dispatches it to the ApplyFix handler.
		// ApplyFix dispatches to the "stub_methods" fixer (the meat).
		// The server then makes an ApplyEdit RPC to the client,
		// whose WorkspaceEditFunc hook temporarily gathers the edits
		// instead of applying them.

		if _, err := env.Editor.Server.ExecuteCommand(env.Ctx, &protocol.ExecuteCommandParams{
			Command:   action.Command.Command,
			Arguments: action.Command.Arguments,
		}); err != nil {
			return nil, err
		}
		return changes, nil // populated as a side effect of ExecuteCommand
	}

	return nil, nil
}

// refsMarker implements the @refs marker.
func refsMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	refs := func(includeDeclaration bool, want []protocol.Location) error {
		got, err := mark.server().References(mark.ctx(), &protocol.ReferenceParams{
			TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(src),
			Context: protocol.ReferenceContext{
				IncludeDeclaration: includeDeclaration,
			},
		})
		if err != nil {
			return err
		}

		return compareLocations(mark, got, want)
	}

	for _, includeDeclaration := range []bool{false, true} {
		// Ignore first 'want' location if we didn't request the declaration.
		// TODO(adonovan): don't assume a single declaration:
		// there may be >1 if corresponding methods are considered.
		want := want
		if !includeDeclaration && len(want) > 0 {
			want = want[1:]
		}
		if err := refs(includeDeclaration, want); err != nil {
			mark.errorf("refs(includeDeclaration=%t) failed: %v",
				includeDeclaration, err)
		}
	}
}

// implementationMarker implements the @implementation marker.
func implementationMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	wantErr := namedArgFunc(mark, "err", convertStringMatcher, stringMatcher{})

	got, err := mark.server().Implementation(mark.ctx(), &protocol.ImplementationParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(src),
	})
	if err != nil && wantErr.empty() {
		mark.errorf("implementation at %s failed: %v", src, err)
		return
	}
	if !wantErr.empty() {
		wantErr.checkErr(mark, err)
		return
	}
	if err := compareLocations(mark, got, want); err != nil {
		mark.errorf("implementation: %v", err)
	}
}

func mcpToolMarker(mark marker, tool string, rawArgs string) {
	if !mark.run.test.mcp {
		mark.errorf("mcp not enabled: add -mcp")
		return
	}
	args := make(map[string]any)
	if err := json.Unmarshal([]byte(rawArgs), &args); err != nil {
		mark.errorf("fail to unmarshal arguments to map[string]any: %v", err)
		return
	}

	// substitutePaths replaces instances of $WORKDIR in string or []string values with
	// the actual working directory.
	var substitutePaths func(any) any
	substitutePaths = func(v any) any {
		switch v := v.(type) {
		case string:
			return strings.ReplaceAll(v, "$WORKDIR", mark.run.env.Sandbox.Workdir.RootURI().Path())

		case []any:
			for i, e := range v {
				if _, ok := e.(string); ok {
					v[i] = substitutePaths(e).(string)
				}
			}
		}
		return v
	}
	// Hack: replace '$WORKDIR' in string arguments with the actual sandbox
	// working directory.
	for k, v := range args {
		args[k] = substitutePaths(v)
	}

	if loc := namedArg(mark, "location", protocol.Location{}); loc != (protocol.Location{}) {
		args["location"] = loc
	}

	res, err := mark.run.env.MCPSession.CallTool(mark.ctx(), &mcp.CallToolParams{
		Name:      tool,
		Arguments: args,
	})
	if err != nil {
		mark.errorf("failed to call mcp tool: %v", err)
		return
	}

	var buf bytes.Buffer
	for i, c := range res.Content {
		text, ok := c.(*mcp.TextContent)
		if !ok {
			mark.errorf("unsupported return content[%v] type: %T", i, c)
			continue
		}
		buf.WriteString(text.Text)
	}
	if !bytes.HasSuffix(buf.Bytes(), []byte{'\n'}) {
		buf.WriteString("\n") // all golden content is newline terminated
	}

	got := buf.String()
	// For portability, replace all (potential) filepath separators with "/".
	got = strings.ReplaceAll(got, string(filepath.Separator), "/")
	// To ensure consistent unified diff output, the working directory path
	// is replaced with "$WORKDIR". This addresses cases where MCP tools
	// include absolute file paths in generated diffs.
	got = strings.ReplaceAll(got, filepath.ToSlash(mark.run.env.Sandbox.Workdir.RootURI().Path()), "$WORKDIR")

	output := namedArg(mark, "output", expect.Identifier(""))
	golden := mark.getGolden(output)
	want, _ := golden.Get(mark.T(), "", []byte(got))
	if diff := compare.Text(string(want), got); diff != "" {
		mark.errorf("unexpected mcp tools call %s return: diff:\n%s", tool, diff)
	}
}

func incomingCallsMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	getCalls := func(item protocol.CallHierarchyItem) ([]protocol.Location, error) {
		calls, err := mark.server().IncomingCalls(mark.ctx(), &protocol.CallHierarchyIncomingCallsParams{Item: item})
		if err != nil {
			return nil, err
		}
		var locs []protocol.Location
		for _, call := range calls {
			locs = append(locs, call.From.URI.Location(call.From.Range))
		}
		return locs, nil
	}
	callHierarchy(mark, src, getCalls, want)
}

func outgoingCallsMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	getCalls := func(item protocol.CallHierarchyItem) ([]protocol.Location, error) {
		calls, err := mark.server().OutgoingCalls(mark.ctx(), &protocol.CallHierarchyOutgoingCallsParams{Item: item})
		if err != nil {
			return nil, err
		}
		var locs []protocol.Location
		for _, call := range calls {
			locs = append(locs, call.To.URI.Location(call.To.Range))
		}
		return locs, nil
	}
	callHierarchy(mark, src, getCalls, want)
}

type callHierarchyFunc = func(protocol.CallHierarchyItem) ([]protocol.Location, error)

func callHierarchy(mark marker, src protocol.Location, getCalls callHierarchyFunc, want []protocol.Location) {
	items, err := mark.server().PrepareCallHierarchy(mark.ctx(), &protocol.CallHierarchyPrepareParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(src),
	})
	if err != nil {
		mark.errorf("PrepareCallHierarchy failed: %v", err)
		return
	}
	if nitems := len(items); nitems != 1 {
		mark.errorf("PrepareCallHierarchy returned %d items, want exactly 1", nitems)
		return
	}
	item := items[0]
	if loc := item.URI.Location(item.Range); loc != src {
		mark.errorf("PrepareCallHierarchy found call %v, want %v", loc, src)
		return
	}
	calls, err := getCalls(items[0])
	if err != nil {
		mark.errorf("call hierarchy failed: %v", err)
		return
	}
	if err := compareLocations(mark, calls, want); err != nil {
		mark.errorf("%s failed: %v", mark.note.Name, err)
	}
}

func inlayhintsMarker(mark marker, g *Golden) {
	hints := mark.run.env.InlayHints(mark.path())

	// Map inlay hints to text edits.
	edits := make([]protocol.TextEdit, len(hints))
	for i, hint := range hints {
		var paddingLeft, paddingRight string
		if hint.PaddingLeft {
			paddingLeft = " "
		}
		if hint.PaddingRight {
			paddingRight = " "
		}
		edits[i] = protocol.TextEdit{
			Range:   protocol.Range{Start: hint.Position, End: hint.Position},
			NewText: fmt.Sprintf("<%s%s%s>", paddingLeft, hint.Label[0].Value, paddingRight),
		}
	}

	m := mark.mapper()
	got, _, err := protocol.ApplyEdits(m, edits)
	if err != nil {
		mark.errorf("ApplyProtocolEdits: %v", err)
		return
	}

	compareGolden(mark, got, g)
}

func prepareRenameMarker(mark marker, src protocol.Location, placeholder string) {
	params := &protocol.PrepareRenameParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(src),
	}
	got, err := mark.server().PrepareRename(mark.ctx(), params)
	if err != nil {
		mark.T().Fatal(err)
	}
	if placeholder == "" {
		if got != nil {
			mark.errorf("PrepareRename(...) = %v, want nil", got)
		}
		return
	}

	want := &protocol.PrepareRenameResult{
		Placeholder: placeholder,
	}
	if span := namedArg(mark, "span", protocol.Location{}); span != (protocol.Location{}) {
		want.Range = span.Range
	} else {
		got.Range = protocol.Range{} // ignore Range
	}
	if diff := cmp.Diff(want, got); diff != "" {
		mark.errorf("mismatching PrepareRename result:\n%s", diff)
	}
}

func subtypesMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	typeHierarchy(mark, src, want, func(item protocol.TypeHierarchyItem) ([]protocol.TypeHierarchyItem, error) {
		return mark.server().Subtypes(mark.ctx(), &protocol.TypeHierarchySubtypesParams{Item: item})
	})
}

func supertypesMarker(mark marker, src protocol.Location, want ...protocol.Location) {
	typeHierarchy(mark, src, want, func(item protocol.TypeHierarchyItem) ([]protocol.TypeHierarchyItem, error) {
		return mark.server().Supertypes(mark.ctx(), &protocol.TypeHierarchySupertypesParams{Item: item})
	})
}

type typeHierarchyFunc = func(item protocol.TypeHierarchyItem) ([]protocol.TypeHierarchyItem, error)

func typeHierarchy(mark marker, src protocol.Location, want []protocol.Location, get typeHierarchyFunc) {
	items, err := mark.server().PrepareTypeHierarchy(mark.ctx(), &protocol.TypeHierarchyPrepareParams{
		TextDocumentPositionParams: protocol.LocationTextDocumentPositionParams(src),
	})
	if err != nil {
		mark.errorf("PrepareTypeHierarchy failed: %v", err)
		return
	}
	if nitems := len(items); nitems != 1 {
		mark.errorf("PrepareTypeHierarchy returned %d items, want exactly 1", nitems)
		return
	}
	if loc := (protocol.Location{URI: items[0].URI, Range: items[0].Range}); loc != src {
		mark.errorf("PrepareTypeHierarchy found type %v, want %v", loc, src)
		return
	}
	items, err = get(items[0])
	if err != nil {
		mark.errorf("type hierarchy failed: %v", err)
		return
	}
	got := []protocol.Location{} // non-nil; cmp.Diff cares
	for _, item := range items {
		got = append(got, item.URI.Location(item.Range))
	}
	if d := cmp.Diff(want, got); d != "" {
		mark.errorf("type hierarchy: unexpected results (-want +got):\n%s", d)
	}
}

// symbolMarker implements the @symbol marker.
func symbolMarker(mark marker, golden *Golden) {
	// Retrieve information about all symbols in this file.
	symbols, err := mark.server().DocumentSymbol(mark.ctx(), &protocol.DocumentSymbolParams{
		TextDocument: protocol.TextDocumentIdentifier{URI: mark.uri()},
	})
	if err != nil {
		mark.errorf("DocumentSymbol request failed: %v", err)
		return
	}

	// Format symbols one per line, sorted (in effect) by first column, a dotted name.
	var lines []string
	for _, symbol := range symbols {
		// Each result element is a union of (legacy)
		// SymbolInformation and (new) DocumentSymbol,
		// so we ascertain which one and then transcode.
		data, err := json.Marshal(symbol)
		if err != nil {
			mark.T().Fatal(err)
		}
		if _, ok := symbol.(map[string]any)["location"]; ok {
			// This case is not reached because Editor initialization
			// enables HierarchicalDocumentSymbolSupport.
			// TODO(adonovan): test this too.
			var sym protocol.SymbolInformation
			if err := json.Unmarshal(data, &sym); err != nil {
				mark.T().Fatal(err)
			}
			mark.errorf("fake Editor doesn't support SymbolInformation")

		} else {
			var sym protocol.DocumentSymbol // new hierarchical hotness
			if err := json.Unmarshal(data, &sym); err != nil {
				mark.T().Fatal(err)
			}

			// Print each symbol in the response tree.
			var visit func(sym protocol.DocumentSymbol, prefix []string)
			visit = func(sym protocol.DocumentSymbol, prefix []string) {
				var out strings.Builder
				out.WriteString(strings.Join(prefix, "."))
				fmt.Fprintf(&out, " %q", sym.Detail)
				if delta := sym.Range.End.Line - sym.Range.Start.Line; delta > 0 {
					fmt.Fprintf(&out, " +%d lines", delta)
				}
				lines = append(lines, out.String())

				for _, child := range sym.Children {
					visit(child, append(prefix, child.Name))
				}
			}
			visit(sym, []string{sym.Name})
		}
	}
	sort.Strings(lines)
	lines = append(lines, "") // match trailing newline in .txtar file
	got := []byte(strings.Join(lines, "\n"))

	// Compare with golden.
	want, ok := golden.Get(mark.T(), "", got)
	if !ok {
		mark.errorf("%s: missing golden file @%s", mark.note.Name, golden.id)
	} else if diff := cmp.Diff(string(got), string(want)); diff != "" {
		mark.errorf("%s: unexpected output: got:\n%s\nwant:\n%s\ndiff:\n%s",
			mark.note.Name, got, want, diff)
	}
}

// compareLocations returns an error message if got and want are not
// the same set of locations. The marker is used only for fmtLoc.
func compareLocations(mark marker, got, want []protocol.Location) error {
	toStrings := func(locs []protocol.Location) []string {
		strs := make([]string, len(locs))
		for i, loc := range locs {
			strs[i] = mark.run.fmtLoc(loc)
		}
		sort.Strings(strs)
		return strs
	}
	if diff := cmp.Diff(toStrings(want), toStrings(got)); diff != "" {
		return fmt.Errorf("incorrect result locations: (got %d, want %d):\n%s",
			len(got), len(want), diff)
	}
	return nil
}

func workspaceSymbolMarker(mark marker, query string, golden *Golden) {
	params := &protocol.WorkspaceSymbolParams{
		Query: query,
	}

	gotSymbols, err := mark.server().Symbol(mark.ctx(), params)
	if err != nil {
		mark.errorf("Symbol(%q) failed: %v", query, err)
		return
	}
	var got bytes.Buffer
	for _, s := range gotSymbols {
		// Omit the txtar position of the symbol location; otherwise edits to the
		// txtar archive lead to unexpected failures.
		loc := mark.run.fmtLocForGolden(s.Location)
		if loc == "" {
			loc = "<unknown>"
		}
		fmt.Fprintf(&got, "%s %s %s\n", loc, s.Name, s.Kind)
	}

	compareGolden(mark, got.Bytes(), golden)
}

// compareGolden compares the content of got with that of g.Get(""), reporting
// errors on any mismatch.
//
// TODO(rfindley): use this helper in more places.
func compareGolden(mark marker, got []byte, g *Golden) {
	want, ok := g.Get(mark.T(), "", got)
	if !ok {
		mark.errorf("missing golden file @%s", g.id)
		return
	}
	// Normalize newline termination: archive files (i.e. Golden content) can't
	// contain non-newline terminated files, except in the special case where the
	// file is completely empty.
	//
	// Note that txtar partitions a contiguous byte slice, so we must copy before
	// appending.
	normalize := func(s []byte) []byte {
		if n := len(s); n > 0 && s[n-1] != '\n' {
			s = append(s[:n:n], '\n') // don't mutate array
		}
		return s
	}
	got = normalize(got)
	want = normalize(want)
	if diff := compare.Bytes(want, got); diff != "" {
		mark.errorf("%s does not match @%s:\n%s", mark.note.Name, g.id, diff)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/callhierarchy/callhierarchy.txt
================================================
This test checks call hierarchy queries.

-ignore_extra_diags due to the initialization cycle.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/callhierarchy

-- incoming/incoming.go --
package incoming

import "golang.org/lsptests/callhierarchy"

// A is exported to test incoming calls across packages
func A() { //@loc(incomingA, "A")
	callhierarchy.D()
}

-- outgoing/outgoing.go --
package outgoing

// B is exported to test outgoing calls across packages
func B() { //@loc(outgoingB, "B")
}

-- hierarchy.go --
package callhierarchy //@loc(hPkg, "callhierarchy")

import "golang.org/lsptests/callhierarchy/outgoing"

func a() { //@loc(hA, "a")
	D()
}

func b() { //@loc(hB, "b")
	D()
}

// C is an exported function
func C() { //@loc(hC, "C")
	D()
	D()
}

// To test hierarchy across function literals
var x = func() { D() } //@loc(hX, "x"),loc(hXGlobal, "x")

// D is exported to test incoming/outgoing calls across packages
func D() { //@ loc(hD, "D"), incomingcalls(hD, hA, hB, hC, hXGlobal, incomingA), outgoingcalls(hD, hE, hF, hG, hH, hI, Generic, outgoingB)
	e()
	x()
	F()
	outgoing.B()

	func() {
		g()
	}()

	var i Interface = impl{}
	i.H()
	i.I()

	s := Struct{}
	s.J()
	s.K()

	Generic[string]()
}

func e() {} //@loc(hE, "e")

// F is an exported function
func F() {} //@loc(hF, "F")

func g() {} //@loc(hG, "g")

type Interface interface {
	H() //@loc(hH, "H")
	I() //@loc(hI, "I")
}

type impl struct{}

func (i impl) H() {}
func (i impl) I() {}

type Struct struct {
	J func() //@loc(hJ, "J")
	K func() //@loc(hK, "K")
}

func Generic[T any]() //@loc(Generic, "Generic")


================================================
FILE: gopls/internal/test/marker/testdata/callhierarchy/issue64451.txt
================================================
This test checks call hierarchy queries involving lambdas, which are
treated as mere statements of their enclosing name function, since
we can't track calls to them.

Calls from a global var decl are reported at the ValueSpec.Names.

See golang/go#64451.

-- go.mod --
module example.com
go 1.0

-- a/a.go --
package a

func Foo() {   //@ loc(Foo, "Foo")
	bar()
}

func bar() { 			//@ loc(bar, "bar")
	go func() { baz() }()
}

func baz() {   //@ loc(baz, "baz")
	bluh()
}

func bluh() {   //@ loc(bluh, "bluh")
	print()
}

var _ = func() int { //@ loc(global, "_")
	baz()
	return 0
}()

func init() { //@ loc(init, "init")
	baz()
}

//@ outgoingcalls(Foo, bar)
//@ outgoingcalls(bar, baz)
//@ outgoingcalls(baz, bluh)
//@ outgoingcalls(bluh)
//@ outgoingcalls(init, baz)

//@ incomingcalls(Foo)
//@ incomingcalls(bar, Foo)
//@ incomingcalls(baz, bar, global, init)
//@ incomingcalls(bluh, baz)
//@ incomingcalls(init)


================================================
FILE: gopls/internal/test/marker/testdata/callhierarchy/issue66923.txt
================================================
Regression test for a crash (#66923) in outgoing calls
to a built-in function (unsafe.Slice).

-- go.mod --
module example.com
go 1.17

-- a/a.go --
package a

import "unsafe"

func A() []int { //@ loc(A, "A"), outgoingcalls(A, UNSAFE)
	return unsafe.Slice(new(int), 1)
}


================================================
FILE: gopls/internal/test/marker/testdata/callhierarchy/issue75230.txt
================================================
Regression test for a crash (golang/go#75230) in outgoing calls
to a built-in method (error.Error).

We (arbitrarily) don't show calls to built-ins without a package,
such as error.Error, hence the empty result asserted below.

-- go.mod --
module example.com
go 1.17

-- a/a.go --
package a

func A(err error) string { //@ loc(A, "A"), outgoingcalls(A)
	return err.Error()
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/add_struct_tags.txt
================================================
This test checks the behavior of the 'Add struct tags' code action without dialogs.

-- flags --
-ignore_extra_diags

-- addtags.go --
package addtags

type A struct {
	x int //@codeaction("x", "refactor.rewrite.addTags", edit=singleline)
	y int //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.addTags", edit=twolines)
	z int //@codeaction(re`()n`, "refactor.rewrite.addTags", edit=entirestruct)
}
-- @entirestruct/addtags.go --
@@ -4,3 +4,3 @@
-	x int //@codeaction("x", "refactor.rewrite.addTags", edit=singleline)
-	y int //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.addTags", edit=twolines)
-	z int //@codeaction(re`()n`, "refactor.rewrite.addTags", edit=entirestruct)
+	x int `json:"x"` //@codeaction("x", "refactor.rewrite.addTags", edit=singleline)
+	y int `json:"y"` //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.addTags", edit=twolines)
+	z int `json:"z"` //@codeaction(re`()n`, "refactor.rewrite.addTags", edit=entirestruct)
-- @singleline/addtags.go --
@@ -4 +4 @@
-	x int //@codeaction("x", "refactor.rewrite.addTags", edit=singleline)
+	x int `json:"x"` //@codeaction("x", "refactor.rewrite.addTags", edit=singleline)
-- @twolines/addtags.go --
@@ -5,2 +5,2 @@
-	y int //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.addTags", edit=twolines)
-	z int //@codeaction(re`()n`, "refactor.rewrite.addTags", edit=entirestruct)
+	y int `json:"y"` //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.addTags", edit=twolines)
+	z int `json:"z"` //@codeaction(re`()n`, "refactor.rewrite.addTags", edit=entirestruct)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/addtest.txt
================================================
This test checks the behavior of the 'add test for FUNC' code action.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/addtest

go 1.18

-- copyrightandbuildconstraint/copyrightandbuildconstraint.go --
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.18

// Package main is for lsp test.
package main

func Foo(in string) string {return in} //@codeaction("Foo", "source.addTest", edit=with_copyright_build_constraint)

-- @with_copyright_build_constraint/copyrightandbuildconstraint/copyrightandbuildconstraint_test.go --
@@ -0,0 +1,32 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/copyrightandbuildconstraint"
+	"testing"
+)
+
+func TestFoo(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := main.Foo(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Foo() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- buildconstraint/buildconstraint.go --
//go:build go1.18

// Package copyright is for lsp test.
package copyright

func Foo(in string) string {return in} //@codeaction("Foo", "source.addTest", edit=with_build_constraint)

-- @with_build_constraint/buildconstraint/buildconstraint_test.go --
@@ -0,0 +1,28 @@
+//go:build go1.18
+
+package copyright_test
+
+import(
+	"golang.org/lsptests/addtest/buildconstraint"
+	"testing"
+)
+
+func TestFoo(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := copyright.Foo(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Foo() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- missingtestfile/missingtestfile.go --
package main

type Bar struct {}

type foo struct {}

func ExportedFunction(in string) string {return in} //@codeaction("ExportedFunction", "source.addTest", edit=missing_test_file_exported_function)

func UnexportedInputParam(in string, f foo) string {return in} //@codeaction("UnexportedInputParam", "source.addTest", edit=missing_test_file_function_unexported_input)

func unexportedFunction(in string) string {return in} //@codeaction("unexportedFunction", "source.addTest", edit=missing_test_file_unexported_function)

func (*Bar) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=missing_test_file_exported_recv_exported_method)

func (*Bar) UnexportedInputParam(in string, f foo) string {return in} //@codeaction("UnexportedInputParam", "source.addTest", edit=missing_test_file_method_unexported_input)

func (*foo) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=missing_test_file_unexported_recv)

-- @missing_test_file_exported_function/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,26 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/missingtestfile"
+	"testing"
+)
+
+func TestExportedFunction(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := main.ExportedFunction(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedFunction() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @missing_test_file_exported_recv_exported_method/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,28 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/missingtestfile"
+	"testing"
+)
+
+func TestBar_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b main.Bar
+			got := b.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @missing_test_file_function_unexported_input/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,24 @@
+package main
+
+import "testing"
+
+func TestUnexportedInputParam(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		f    foo
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := UnexportedInputParam(tt.in, tt.f)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("UnexportedInputParam() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @missing_test_file_method_unexported_input/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,26 @@
+package main
+
+import "testing"
+
+func TestBar_UnexportedInputParam(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		f    foo
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b Bar
+			got := b.UnexportedInputParam(tt.in, tt.f)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("UnexportedInputParam() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @missing_test_file_unexported_function/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,23 @@
+package main
+
+import "testing"
+
+func Test_unexportedFunction(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := unexportedFunction(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedFunction() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @missing_test_file_unexported_recv/missingtestfile/missingtestfile_test.go --
@@ -0,0 +1,25 @@
+package main
+
+import "testing"
+
+func Test_foo_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var f foo
+			got := f.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- xpackagetestfile/xpackagetestfile.go --
package main

func ExportedFunction(in string) string {return in} //@codeaction("ExportedFunction", "source.addTest", edit=xpackage_exported_function)
func unexportedFunction(in string) string {return in} //@codeaction("unexportedFunction", "source.addTest", edit=xpackage_unexported_function)

type Bar struct {}

func (*Bar) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=xpackage_exported_recv_exported_method)
func (*Bar) unexportedMethod(in string) string {return in} //@codeaction("unexportedMethod", "source.addTest", edit=xpackage_exported_recv_unexported_method)

type foo struct {}

func (*foo) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=xpackage_unexported_recv_exported_method)
func (*foo) unexportedMethod(in string) string {return in} //@codeaction("unexportedMethod", "source.addTest", edit=xpackage_unexported_recv_unexported_method)

-- xpackagetestfile/xpackagetestfile_test.go --
package main

-- @xpackage_exported_function/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,22 @@
+import "testing"
+
+
+func TestExportedFunction(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := ExportedFunction(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedFunction() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @xpackage_unexported_function/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,22 @@
+import "testing"
+
+
+func Test_unexportedFunction(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := unexportedFunction(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedFunction() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @xpackage_exported_recv_exported_method/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func TestBar_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b Bar
+			got := b.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @xpackage_exported_recv_unexported_method/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func TestBar_unexportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b Bar
+			got := b.unexportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @xpackage_unexported_recv_exported_method/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func Test_foo_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var f foo
+			got := f.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @xpackage_unexported_recv_unexported_method/xpackagetestfile/xpackagetestfile_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func Test_foo_unexportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var f foo
+			got := f.unexportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- aliasreceiver/aliasreceiver.go --
package main

type bar0 struct {}
type bar1 = bar0
type Bar = bar1

func (*Bar) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=pointer_receiver_exported_method)
func (*Bar) unexportedMethod(in string) string {return in} //@codeaction("unexportedMethod", "source.addTest", edit=pointer_receiver_unexported_method)

type foo0 struct {}
type foo1 = foo0
type foo = foo1

func (foo) ExportedMethod(in string) string {return in} //@codeaction("ExportedMethod", "source.addTest", edit=alias_receiver_exported_method)
func (foo) unexportedMethod(in string) string {return in} //@codeaction("unexportedMethod", "source.addTest", edit=alias_receiver_unexported_method)

type baz0 struct{}
type baz1 = baz0
type baz = baz1

func newBaz0() baz0 {return baz0{}}

func (baz) method(in string) string {return in} //@codeaction("method", "source.addTest", edit=alias_constructor_on_underlying_type)

type qux0 struct{}
type qux1 = qux0
type qux2 = qux1
type Qux = *qux2

func newQux1() (qux1, error) {return qux1{}, nil}

func (Qux) method(in string) string {return in} //@codeaction("method", "source.addTest", edit=alias_constructor_on_different_alias_type)

-- aliasreceiver/aliasreceiver_test.go --
package main

-- @pointer_receiver_exported_method/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func TestBar_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b Bar
+			got := b.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @pointer_receiver_unexported_method/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func TestBar_unexportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var b Bar
+			got := b.unexportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @alias_receiver_exported_method/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func Test_foo_ExportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var f foo
+			got := f.ExportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("ExportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @alias_receiver_unexported_method/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,24 @@
+import "testing"
+
+
+func Test_foo_unexportedMethod(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			// TODO: construct the receiver type.
+			var f foo
+			got := f.unexportedMethod(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("unexportedMethod() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @alias_constructor_on_underlying_type/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,23 @@
+import "testing"
+
+
+func Test_baz_method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b := newBaz0()
+			got := b.method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @alias_constructor_on_different_alias_type/aliasreceiver/aliasreceiver_test.go --
@@ -3 +3,26 @@
+import "testing"
+
+
+func TestQux_method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			q, err := newQux1()
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got := q.method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- multiinputoutput/multiinputoutput.go --
package main

func Foo(in, in2, in3, in4 string) (out, out1, out2 string) {return "", "", ""} //@codeaction("Foo", "source.addTest", edit=multi_input_output)

-- @multi_input_output/multiinputoutput/multiinputoutput_test.go --
@@ -0,0 +1,37 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/multiinputoutput"
+	"testing"
+)
+
+func TestFoo(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in    string
+		in2   string
+		in3   string
+		in4   string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.Foo(tt.in, tt.in2, tt.in3, tt.in4)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Foo() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Foo() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Foo() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- xpackagerename/xpackagerename.go --
package main

import (
  mytime "time"
  myast "go/ast"
  mytest "testing"
)

var local mytest.T

func Foo(t mytime.Time, a *myast.Node) (mytime.Time, *myast.Node) {return t, a} //@codeaction("Foo", "source.addTest", edit=xpackage_rename)

-- @xpackage_rename/xpackagerename/xpackagerename_test.go --
@@ -0,0 +1,33 @@
+package main_test
+
+import(
+	myast "go/ast"
+	"golang.org/lsptests/addtest/xpackagerename"
+	mytest "testing"
+	mytime "time"
+)
+
+func TestFoo(t *mytest.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		t     mytime.Time
+		a     *myast.Node
+		want  mytime.Time
+		want2 *myast.Node
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *mytest.T) {
+			got, got2 := main.Foo(tt.t, tt.a)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Foo() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Foo() = %v, want %v", got2, tt.want2)
+			}
+		})
+	}
+}
-- xtestpackagerename/xtestpackagerename.go --
package main

import (
  mytime "time"
  myast "go/ast"
  mytest "testing"
)

var local mytest.T

func Foo(t mytime.Time, a *myast.Node) (mytime.Time, *myast.Node) {return t, a} //@codeaction("Foo", "source.addTest", edit=xtest_package_rename)

-- xtestpackagerename/xtestpackagerename_test.go --
package main_test

import (
	yourast "go/ast"
	yourtest "testing"
	yourtime "time"
)

var fooTime = yourtime.Time{}
var fooNode = yourast.Node{}
var fooT yourtest.T

-- @xtest_package_rename/xtestpackagerename/xtestpackagerename_test.go --
@@ -7 +7,2 @@
+
+	"golang.org/lsptests/addtest/xtestpackagerename"
@@ -13 +15,25 @@
+
+func TestFoo(t *yourtest.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		t     yourtime.Time
+		a     *yourast.Node
+		want  yourtime.Time
+		want2 *yourast.Node
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *yourtest.T) {
+			got, got2 := main.Foo(tt.t, tt.a)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Foo() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Foo() = %v, want %v", got2, tt.want2)
+			}
+		})
+	}
+}
-- returnwitherror/returnwitherror.go --
package main

func OnlyErr() error {return nil} //@codeaction("OnlyErr", "source.addTest", edit=return_only_error)
func StringErr() (string, error) {return "", nil} //@codeaction("StringErr", "source.addTest", edit=return_string_error)
func MultipleStringErr() (string, string, string, error) {return "", "", "", nil} //@codeaction("MultipleStringErr", "source.addTest", edit=return_multiple_string_error)

-- @return_only_error/returnwitherror/returnwitherror_test.go --
@@ -0,0 +1,29 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/returnwitherror"
+	"testing"
+)
+
+func TestOnlyErr(t *testing.T) {
+	tests := []struct {
+		name    string // description of this test case
+		wantErr bool
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotErr := main.OnlyErr()
+			if gotErr != nil {
+				if !tt.wantErr {
+					t.Errorf("OnlyErr() failed: %v", gotErr)
+				}
+				return
+			}
+			if tt.wantErr {
+				t.Fatal("OnlyErr() succeeded unexpectedly")
+			}
+		})
+	}
+}
-- @return_string_error/returnwitherror/returnwitherror_test.go --
@@ -0,0 +1,34 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/returnwitherror"
+	"testing"
+)
+
+func TestStringErr(t *testing.T) {
+	tests := []struct {
+		name    string // description of this test case
+		want    string
+		wantErr bool
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, gotErr := main.StringErr()
+			if gotErr != nil {
+				if !tt.wantErr {
+					t.Errorf("StringErr() failed: %v", gotErr)
+				}
+				return
+			}
+			if tt.wantErr {
+				t.Fatal("StringErr() succeeded unexpectedly")
+			}
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("StringErr() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @return_multiple_string_error/returnwitherror/returnwitherror_test.go --
@@ -0,0 +1,42 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/returnwitherror"
+	"testing"
+)
+
+func TestMultipleStringErr(t *testing.T) {
+	tests := []struct {
+		name    string // description of this test case
+		want    string
+		want2   string
+		want3   string
+		wantErr bool
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3, gotErr := main.MultipleStringErr()
+			if gotErr != nil {
+				if !tt.wantErr {
+					t.Errorf("MultipleStringErr() failed: %v", gotErr)
+				}
+				return
+			}
+			if tt.wantErr {
+				t.Fatal("MultipleStringErr() succeeded unexpectedly")
+			}
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("MultipleStringErr() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("MultipleStringErr() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("MultipleStringErr() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- constructor/constructor.go --
package main

// Constructor returns the type T.
func NewReturnType() ReturnType {return ReturnType{}}

type ReturnType struct {}

func (*ReturnType) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_return_type)

// Constructor returns the type T and an error.
func NewReturnTypeError() (ReturnTypeError, error) {return ReturnTypeError{}, nil}

type ReturnTypeError struct {}

func (*ReturnTypeError) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_return_type_error)

// Constructor returns the type *T.
func NewReturnPtr() *ReturnPtr {return nil}

type ReturnPtr struct {}

func (*ReturnPtr) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_return_ptr)

// Constructor returns the type *T and an error.
func NewReturnPtrError() (*ReturnPtrError, error) {return nil, nil}

type ReturnPtrError struct {}

func (*ReturnPtrError) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_return_ptr_error)

-- @constructor_return_type/constructor/constructor_test.go --
@@ -0,0 +1,27 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructor"
+	"testing"
+)
+
+func TestReturnType_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewReturnType()
+			got := r.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @constructor_return_type_error/constructor/constructor_test.go --
@@ -0,0 +1,30 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructor"
+	"testing"
+)
+
+func TestReturnTypeError_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r, err := main.NewReturnTypeError()
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got := r.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @constructor_return_ptr/constructor/constructor_test.go --
@@ -0,0 +1,27 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructor"
+	"testing"
+)
+
+func TestReturnPtr_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewReturnPtr()
+			got := r.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @constructor_return_ptr_error/constructor/constructor_test.go --
@@ -0,0 +1,30 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructor"
+	"testing"
+)
+
+func TestReturnPtrError_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r, err := main.NewReturnPtrError()
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got := r.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- constructorcomparison/constructorcomparison.go --
package main

// Foo have two constructors. NewFoo is preferred over others.
func CreateAFoo() Foo {return Foo{}}
func NewFoo() Foo {return Foo{}}

type Foo struct{}

func (*Foo) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_comparison_new)

// Bar have two constructors. Bar is preferred due to alphabetical ordering.
func ABar() (Bar, error) {return Bar{}, nil}
// func CreateABar() Bar {return Bar{}}

type Bar struct{}

func (*Bar) Method(in string) string {return in} //@codeaction("Method", "source.addTest", edit=constructor_comparison_alphabetical)

-- @constructor_comparison_new/constructorcomparison/constructorcomparison_test.go --
@@ -0,0 +1,27 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructorcomparison"
+	"testing"
+)
+
+func TestFoo_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f := main.NewFoo()
+			got := f.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- @constructor_comparison_alphabetical/constructorcomparison/constructorcomparison_test.go --
@@ -0,0 +1,30 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/constructorcomparison"
+	"testing"
+)
+
+func TestBar_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		in   string
+		want string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			b, err := main.ABar()
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got := b.Method(tt.in)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
-- unnamedparam/unnamedparam.go --
package main

import "time"

func FooInputBasic(one, two, _ string, _ int) (out, out1, out2 string) {return "", "", ""} //@codeaction("Foo", "source.addTest", edit=function_basic_type)

func FooInputStruct(one string, _ time.Time) (out, out1, out2 string) {return "", "", ""} //@codeaction("Foo", "source.addTest", edit=function_struct_type)

func FooInputPtr(one string, _ *time.Time) (out, out1, out2 string) {return "", "", ""} //@codeaction("Foo", "source.addTest", edit=function_ptr_type)

func FooInputFunc(one string, _ func(time.Time) *time.Time) (out, out1, out2 string) {return "", "", ""} //@codeaction("Foo", "source.addTest", edit=function_func_type)

type BarInputBasic struct{}

func NewBarInputBasic(one, two, _ string, _ int) *BarInputBasic {return nil}

func (r *BarInputBasic) Method(one, two, _ string, _ int) {} //@codeaction("Method", "source.addTest", edit=constructor_basic_type)

type BarInputStruct struct{}

func NewBarInputStruct(one string, _ time.Time) *BarInputStruct {return nil}

func (r *BarInputStruct) Method(one string, _ time.Time) {} //@codeaction("Method", "source.addTest", edit=constructor_struct_type)

type BarInputPtr struct{}

func NewBarInputPtr(one string, _ *time.Time) *BarInputPtr {return nil}

func (r *BarInputPtr) Method(one string, _ *time.Time) {} //@codeaction("Method", "source.addTest", edit=constructor_ptr_type)

type BarInputFunction struct{}

func NewBarInputFunction(one string, _ func(time.Time) *time.Time) *BarInputFunction {return nil}

func (r *BarInputFunction) Method(one string, _ func(time.Time) *time.Time) {} //@codeaction("Method", "source.addTest", edit=constructor_func_type)

-- @function_basic_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,35 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+)
+
+func TestFooInputBasic(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		one   string
+		two   string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.FooInputBasic(tt.one, tt.two, "", 0)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("FooInputBasic() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("FooInputBasic() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("FooInputBasic() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @function_func_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,35 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestFooInputFunc(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		one   string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.FooInputFunc(tt.one, nil)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("FooInputFunc() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("FooInputFunc() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("FooInputFunc() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @function_ptr_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,35 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestFooInputPtr(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		one   string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.FooInputPtr(tt.one, nil)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("FooInputPtr() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("FooInputPtr() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("FooInputPtr() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @function_struct_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,35 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestFooInputStruct(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		one   string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.FooInputStruct(tt.one, time.Time{})
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("FooInputStruct() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("FooInputStruct() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("FooInputStruct() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @constructor_basic_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,26 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+)
+
+func TestBarInputBasic_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for receiver constructor.
+		cone string
+		ctwo string
+		// Named input parameters for target function.
+		one string
+		two string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewBarInputBasic(tt.cone, tt.ctwo, "", 0)
+			r.Method(tt.one, tt.two, "", 0)
+		})
+	}
+}
-- @constructor_func_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,25 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestBarInputFunction_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for receiver constructor.
+		cone string
+		// Named input parameters for target function.
+		one string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewBarInputFunction(tt.cone, nil)
+			r.Method(tt.one, nil)
+		})
+	}
+}
-- @constructor_ptr_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,25 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestBarInputPtr_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for receiver constructor.
+		cone string
+		// Named input parameters for target function.
+		one string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewBarInputPtr(tt.cone, nil)
+			r.Method(tt.one, nil)
+		})
+	}
+}
-- @constructor_struct_type/unnamedparam/unnamedparam_test.go --
@@ -0,0 +1,25 @@
+package main_test
+
+import(
+	"golang.org/lsptests/addtest/unnamedparam"
+	"testing"
+	"time"
+)
+
+func TestBarInputStruct_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for receiver constructor.
+		cone string
+		// Named input parameters for target function.
+		one string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			r := main.NewBarInputStruct(tt.cone, time.Time{})
+			r.Method(tt.one, time.Time{})
+		})
+	}
+}
-- contextinput/contextinput.go --
package main

import "context"

func Function(ctx context.Context, _, _ string) (out, out1, out2 string) {return "", "", ""} //@codeaction("Function", "source.addTest", edit=function_context)

type Foo struct {}

func NewFoo(ctx context.Context) (*Foo, error) {return nil, nil}

func (*Foo) Method(ctx context.Context, _, _ string)  (out, out1, out2 string) {return "", "", ""} //@codeaction("Method", "source.addTest", edit=method_context)
-- contextinput/contextinput_test.go --
package main_test

import renamedctx "context"

var local renamedctx.Context

-- @function_context/contextinput/contextinput_test.go --
@@ -3 +3,3 @@
-import renamedctx "context"
+import (
+	renamedctx "context"
+	"testing"
@@ -5 +7,3 @@
+	"golang.org/lsptests/addtest/contextinput"
+)
+
@@ -7 +12,26 @@
+
+func TestFunction(t *testing.T) {
+	tests := []struct {
+		name  string // description of this test case
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.Function(renamedctx.Background(), "", "")
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Function() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @method_context/contextinput/contextinput_test.go --
@@ -3 +3,3 @@
-import renamedctx "context"
+import (
+	renamedctx "context"
+	"testing"
@@ -5 +7,3 @@
+	"golang.org/lsptests/addtest/contextinput"
+)
+
@@ -7 +12,30 @@
+
+func TestFoo_Method(t *testing.T) {
+	tests := []struct {
+		name  string // description of this test case
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f, err := main.NewFoo(renamedctx.Background())
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got, got2, got3 := f.Method(renamedctx.Background(), "", "")
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- typeparameter/typeparameter.go --
package main

func Function[T any] () {} // no suggested fix

type Foo struct {}

func NewFoo()

func (*Foo) Method[T any]() {} // no suggested fix
-- varargsinput/varargsinput.go --
package main

func Function(args ...string) (out, out1, out2 string) {return args[0], "", ""} //@codeaction("Function", "source.addTest", edit=function_varargsinput)

type Foo struct {}

func NewFoo(args ...string) (*Foo, error) { 
    _ = args
    return nil, nil 
}

func (*Foo) Method(args ...string)  (out, out1, out2 string) {return args[0], "", ""} //@codeaction("Method", "source.addTest", edit=method_varargsinput)
-- varargsinput/varargsinput_test.go --
package main_test
-- @function_varargsinput/varargsinput/varargsinput_test.go --
@@ -2 +2,34 @@
+
+import (
+	"testing"
+
+	"golang.org/lsptests/addtest/varargsinput"
+)
+
+func TestFunction(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for target function.
+		args  []string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.Function(tt.args...)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Function() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @method_varargsinput/varargsinput/varargsinput_test.go --
@@ -2 +2,40 @@
+
+import (
+	"testing"
+
+	"golang.org/lsptests/addtest/varargsinput"
+)
+
+func TestFoo_Method(t *testing.T) {
+	tests := []struct {
+		name string // description of this test case
+		// Named input parameters for receiver constructor.
+		cargs []string
+		// Named input parameters for target function.
+		args  []string
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f, err := main.NewFoo(tt.cargs...)
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got, got2, got3 := f.Method(tt.args...)
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- unusedvarargsinput/unusedvarargsinput.go --
package main

func Function(_ ...string) (out, out1, out2 string) {return "", "", ""} //@codeaction("Function", "source.addTest", edit=function_unusedvarargsinput)

type Foo struct {}

func NewFoo(_ ...string) (*Foo, error) { 
    return nil, nil 
}

func (*Foo) Method(_ ...string)  (out, out1, out2 string) {return "", "", ""} //@codeaction("Method", "source.addTest", edit=method_unusedvarargsinput)
-- unusedvarargsinput/unusedvarargsinput_test.go --
package main_test
-- @function_unusedvarargsinput/unusedvarargsinput/unusedvarargsinput_test.go --
@@ -2 +2,32 @@
+
+import (
+	"testing"
+
+	"golang.org/lsptests/addtest/unusedvarargsinput"
+)
+
+func TestFunction(t *testing.T) {
+	tests := []struct {
+		name  string // description of this test case
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, got2, got3 := main.Function()
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Function() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Function() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}
-- @method_unusedvarargsinput/unusedvarargsinput/unusedvarargsinput_test.go --
@@ -2 +2,36 @@
+
+import (
+	"testing"
+
+	"golang.org/lsptests/addtest/unusedvarargsinput"
+)
+
+func TestFoo_Method(t *testing.T) {
+	tests := []struct {
+		name  string // description of this test case
+		want  string
+		want2 string
+		want3 string
+	}{
+		// TODO: Add test cases.
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			f, err := main.NewFoo()
+			if err != nil {
+				t.Fatalf("could not construct receiver type: %v", err)
+			}
+			got, got2, got3 := f.Method()
+			// TODO: update the condition below to compare got with tt.want.
+			if true {
+				t.Errorf("Method() = %v, want %v", got, tt.want)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got2, tt.want2)
+			}
+			if true {
+				t.Errorf("Method() = %v, want %v", got3, tt.want3)
+			}
+		})
+	}
+}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/change_quote.txt
================================================
This test checks the behavior of the 'change quote' code action.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/changequote

go 1.18

-- a.go --
package changequote

import (
	"fmt"
)

func foo() {
	var s string
	s = "hello" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a1)
	s = `hello` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a2)
	s = "hello\tworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a3)
	s = `hello	world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a4)
	s = "hello\nworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a5)
	// add a comment  to avoid affect diff compute
	s = `hello
world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a6)
	s = "hello\"world" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a7)
	s = `hello"world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a8)
	s = "hello\x1bworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", err=re"found 0 CodeActions")
	s = "hello`world" //@codeaction(`"`, "refactor.rewrite.changeQuote", err=re"found 0 CodeActions")
	s = "hello\x7fworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", err=re"found 0 CodeActions")
	fmt.Println(s)
}

-- @a1/a.go --
@@ -9 +9 @@
-	s = "hello" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a1)
+	s = `hello` //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a1)
-- @a2/a.go --
@@ -10 +10 @@
-	s = `hello` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a2)
+	s = "hello" //@codeaction("`", "refactor.rewrite.changeQuote", edit=a2)
-- @a3/a.go --
@@ -11 +11 @@
-	s = "hello\tworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a3)
+	s = `hello	world` //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a3)
-- @a4/a.go --
@@ -12 +12 @@
-	s = `hello	world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a4)
+	s = "hello\tworld" //@codeaction("`", "refactor.rewrite.changeQuote", edit=a4)
-- @a5/a.go --
@@ -13 +13,2 @@
-	s = "hello\nworld" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a5)
+	s = `hello
+world` //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a5)
-- @a6/a.go --
@@ -15,2 +15 @@
-	s = `hello
-world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a6)
+	s = "hello\nworld" //@codeaction("`", "refactor.rewrite.changeQuote", edit=a6)
-- @a7/a.go --
@@ -17 +17 @@
-	s = "hello\"world" //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a7)
+	s = `hello"world` //@codeaction(`"`, "refactor.rewrite.changeQuote", edit=a7)
-- @a8/a.go --
@@ -18 +18 @@
-	s = `hello"world` //@codeaction("`", "refactor.rewrite.changeQuote", edit=a8)
+	s = "hello\"world" //@codeaction("`", "refactor.rewrite.changeQuote", edit=a8)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/eliminate_dot_import.txt
================================================
This test checks the behavior of the 'remove dot import' code action.

-- go.mod --
module example.com

go 1.18

-- a.go --
package dotimport

// Base case: action is OK.

import (
	. "fmt" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a1)
	. "bytes" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a2)
	. "time" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a3)
)

var _ = a

func a() {
	Println("hello")

	buf := NewBuffer(nil)
	buf.Grow(10)

	_ = Ticker{C: nil}
}

-- @a1/a.go --
@@ -6 +6 @@
-	. "fmt" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a1)
+	"fmt" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a1)
@@ -14 +14 @@
-	Println("hello")
+	fmt.Println("hello")
-- @a2/a.go --
@@ -7 +7 @@
-	. "bytes" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a2)
+	"bytes" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a2)
@@ -16 +16 @@
-	buf := NewBuffer(nil)
+	buf := bytes.NewBuffer(nil)
-- @a3/a.go --
@@ -8 +8 @@
-	. "time" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a3)
+	"time" //@codeaction(`.`, "refactor.rewrite.eliminateDotImport", edit=a3)
@@ -19 +19 @@
-	_ = Ticker{C: nil}
+	_ = time.Ticker{C: nil}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract-variadic-63287.txt
================================================
This test exercises extract on a variadic function.
It is a regression test for bug #63287 in which
the final parameter's "..." would go missing.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

//@codeaction(block, "refactor.extract.function", edit=out)

func _() {
	var logf func(string, ...any)
	{ println(logf) } //@loc(block, re`{[^}]*}`)
}

-- @out/a/a.go --
@@ -7 +7 @@
-	{ println(logf) } //@loc(block, re`{[^}]*}`)
+	{ newFunction(logf) } //@loc(block, re`{[^}]*}`)
@@ -10 +10,4 @@
+func newFunction(logf func( string,  ...any)) {
+	println(logf)
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_anonymous_struct.txt
================================================
This test checks of the behavior of extract function when the extracted block includes anonymous structs.
-- go.mod --
module mod.com

go 1.12
-- a/a.go --
package a

func _() {
	var x struct{ y int } //@codeaction("var", "refactor.extract.function", end=endA, result=anonA)
	println(x.y) //@loc(endA, ")")
}

-- b/b.go --
package b

func _() {
	type T struct {
		y int
	}
	var x T //@codeaction("var", "refactor.extract.function", end=endB, err="the code refers to a local type")
	println(x.y) //@loc(endB, ")")
}

-- @anonA/a/a.go --
package a

func _() {
	newFunction() //@loc(endA, ")")
}

func newFunction() {
	var x struct{ y int } //@codeaction("var", "refactor.extract.function", end=endA, result=anonA)
	println(x.y)
}

-- d/d.go --
package d

func _() {
	s := []struct{ y int }{
		{y: 1},
		{y: 2},
	}
	for _, v := range s { //@codeaction("for", "refactor.extract.function", end=endD, result=anonD)
		println(v.y)
	} //@loc(endD, "}")
}

-- @anonD/d/d.go --
package d

func _() {
	s := []struct{ y int }{
		{y: 1},
		{y: 2},
	}
	newFunction(s) //@loc(endD, "}")
}

func newFunction(s []struct{y int}) {
	for _, v := range s { //@codeaction("for", "refactor.extract.function", end=endD, result=anonD)
		println(v.y)
	}
}

-- e/e.go --
package e

func _() {
	var x int
	s := []struct { //@codeaction("s", "refactor.extract.function", end=endE, result=anonE)
		y int
	}{
		{y: 1},
		{y: 2},
	}
	x = s[0].y //@loc(endE, "x = s[0].y")
	println(x)
}

-- @anonE/e/e.go --
package e

func _() {
	var x int
	x = newFunction(x) //@loc(endE, "x = s[0].y")
	println(x)
}

func newFunction(x int) int {
	s := []struct { //@codeaction("s", "refactor.extract.function", end=endE, result=anonE)
		y int
	}{
		{y: 1},
		{y: 2},
	}
	x = s[0].y
	return x
}

-- f/f.go --
package f
func _() int {
	x := struct{ y int } { y: 1 } //@codeaction("x", "refactor.extract.function", end=endF, result=anonF)
	return x.y //@loc(endF, "y")
}

-- @anonF/f/f.go --
package f
func _() int {
	return newFunction() //@loc(endF, "y")
}

func newFunction() int {
	x := struct{ y int }{y: 1} //@codeaction("x", "refactor.extract.function", end=endF, result=anonF)
	return x.y
}

-- g/g.go --
package g

import "fmt"

func _() error {
	x := struct{ y error }{fmt.Errorf("test error")}
	return x.y //@ loc(endG, "y"), codeaction("return", "refactor.extract.function", end=endG, result=anonG)
}

-- @anonG/g/g.go --
package g

import "fmt"

func _() error {
	x := struct{ y error }{fmt.Errorf("test error")}
	return newFunction(x) //@ loc(endG, "y"), codeaction("return", "refactor.extract.function", end=endG, result=anonG)
}

func newFunction(x struct{y error}) error {
	return x.y
}

-- h/h.go --
package h

import "fmt"

func _() string {
	type A error
	type B struct {
		A
	}
	a := B{A: fmt.Errorf("test error")} //@codeaction("a", "refactor.extract.function", end=endH, err="the code refers to a local type")
	return a.Error() //@loc(endH, "Error()")
}

-- i/i.go --
package i

import "fmt"

func _() string {
	var a struct{ e error } //@codeaction("var", "refactor.extract.function", end=endI, result=anonI)
	a.e = fmt.Errorf("test error")
	return a.e.Error() //@loc(endI, "Error()")
}

-- @anonI/i/i.go --
package i

import "fmt"

func _() string {
	return newFunction() //@loc(endI, "Error()")
}

func newFunction() string {
	var a struct{ e error } //@codeaction("var", "refactor.extract.function", end=endI, result=anonI)
	a.e = fmt.Errorf("test error")
	return a.e.Error()
}

-- j/j.go --
package j

import "unsafe"

func _() uintptr {
	var x struct{ p unsafe.Pointer }
	y := uintptr(x.p) //@codeaction("y", "refactor.extract.function", end=endJ, result=anonJ)
	return y //@loc(endJ, "y")
}

-- @anonJ/j/j.go --
package j

import "unsafe"

func _() uintptr {
	var x struct{ p unsafe.Pointer }
	return newFunction(x) //@loc(endJ, "y")
}

func newFunction(x struct{p unsafe.Pointer}) uintptr {
	y := uintptr(x.p) //@codeaction("y", "refactor.extract.function", end=endJ, result=anonJ)
	return y
}

-- k/k.go --
package k

import "unsafe"

func _(x int) unsafe.Pointer {
	type A struct {
		p unsafe.Pointer
	}
	c := A{p: unsafe.Pointer(&x)} //@codeaction("c", "refactor.extract.function", end=endK, err="the code refers to a local type")
	return c.p //@loc(endK, "c.p")
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_control.txt
================================================
This test verifies various behaviors of function extraction involving free control statements.

-- go.mod --
module mod.test/extract

go 1.18

-- freecontrol.go --
package extract

//@codeaction(ifCondContinue, "refactor.extract.function", edit=freeControl1)
//@codeaction(ifCondGotoLabel, "refactor.extract.function", edit=freeControl2)
//@codeaction(ifCondGotoLabelWithLabel, "refactor.extract.function", edit=freeControl3)
//@codeaction(multipleCtrl, "refactor.extract.function", edit=freeControl4)
//@codeaction(multipleCtrlNotAllSelected, "refactor.extract.function", edit=freeControl5)
//@codeaction(ctrlVarExists, "refactor.extract.function", edit=freeControl6)
//@codeaction(twoReturns, "refactor.extract.function", edit=freeControl7)
//@codeaction(forWithLabel, "refactor.extract.function", edit=freeControl8)

func FuncContinue(cond bool) {
	for range "abc" {
		if cond { //@ loc(ifCondContinue, re`(?s)if.*println.0.`)
			continue
		}
		println(0)
	}
}

func FuncGoTo(cond bool) {
	for range "abc" {
		if cond { //@ loc(ifCondGotoLabel, re`(?s)if.*println.1.`), loc(ifCondGotoLabelWithLabel, re`(?s)if.*goto.label1....`)
			goto label1
		}
	label1:
		println(1)
	}
}

func FuncMultipleCtrl(x int) {
	for range "abc" {
		if x < 10 { //@ loc(multipleCtrl, re`(?s)if.x.*return...next1....`), loc(multipleCtrlNotAllSelected, re`(?s)if.x.*break....`)
			continue
		}
		if x > 2 {
			break
		}
		if x == 1 {
			return //next1
		}
	}
}

func FuncCtrlVarExists(x int) {
	ctrl := "abc"
	for range ctrl {
		if x < 10 { //@ loc(ctrlVarExists, re`(?s)if.x.*continue...next2....`)
			continue //next2
		}
	}
}

func FuncTwoReturns(x int) int {
 outer:
	for range "abc" {
		if x < 10 { //@ loc(twoReturns, re`(?s)if.x.*return.1....`)
			return 0
		}
		test := x - 4
		if test > 2 {
			continue
		}
		if test == 10 {
			return 1
		}

		for range "def" { //@ loc(forWithLabel, re`(?s)for.*outer.........`)
			if x < 2 {
				continue
			}
			if x > 10 {
				continue outer
			}
		}
	}
	return 0
}
-- @freeControl1/freecontrol.go --
@@ -14 +14,3 @@
-		if cond { //@ loc(ifCondContinue, re`(?s)if.*println.0.`)
+		ctrl := newFunction(cond)
+		switch ctrl {
+		case 1:
@@ -17 +19 @@
-		println(0)
@@ -21 +22,8 @@
+func newFunction(cond bool) int {
+	if cond { //@ loc(ifCondContinue, re`(?s)if.*println.0.`)
+		return 1
+	}
+	println(0)
+	return 0
+}
+
-- @freeControl2/freecontrol.go --
@@ -23,5 +23 @@
-		if cond { //@ loc(ifCondGotoLabel, re`(?s)if.*println.1.`), loc(ifCondGotoLabelWithLabel, re`(?s)if.*goto.label1....`)
-			goto label1
-		}
-	label1:
-		println(1)
+		newFunction(cond)
@@ -31 +27,8 @@
+func newFunction(cond bool) {
+	if cond { //@ loc(ifCondGotoLabel, re`(?s)if.*println.1.`), loc(ifCondGotoLabelWithLabel, re`(?s)if.*goto.label1....`)
+		goto label1
+	}
+label1:
+	println(1)
+}
+
-- @freeControl3/freecontrol.go --
@@ -23 +23,3 @@
-		if cond { //@ loc(ifCondGotoLabel, re`(?s)if.*println.1.`), loc(ifCondGotoLabelWithLabel, re`(?s)if.*goto.label1....`)
+		ctrl := newFunction(cond)
+		switch ctrl {
+		case 1:
@@ -31 +33,7 @@
+func newFunction(cond bool) int {
+	if cond { //@ loc(ifCondGotoLabel, re`(?s)if.*println.1.`), loc(ifCondGotoLabelWithLabel, re`(?s)if.*goto.label1....`)
+		return 1
+	}
+	return 0
+}
+
-- @freeControl4/freecontrol.go --
@@ -33,2 +33,3 @@
-		if x < 10 { //@ loc(multipleCtrl, re`(?s)if.x.*return...next1....`), loc(multipleCtrlNotAllSelected, re`(?s)if.x.*break....`)
-			continue
+		shouldReturn, ctrl := newFunction(x)
+		if shouldReturn {
+			return
@@ -36 +37,4 @@
-		if x > 2 {
+		switch ctrl {
+		case 1:
+			continue
+		case 2:
@@ -39,3 +43 @@
-		if x == 1 {
-			return //next1
-		}
@@ -45 +46,14 @@
+func newFunction(x int) (bool, int) {
+	if x < 10 { //@ loc(multipleCtrl, re`(?s)if.x.*return...next1....`), loc(multipleCtrlNotAllSelected, re`(?s)if.x.*break....`)
+		return false, 1
+	}
+	if x > 2 {
+		return false, 2
+	}
+	if x == 1 {
+		return true, //next1
+		0
+	}
+	return false, 0
+}
+
-- @freeControl5/freecontrol.go --
@@ -33 +33,3 @@
-		if x < 10 { //@ loc(multipleCtrl, re`(?s)if.x.*return...next1....`), loc(multipleCtrlNotAllSelected, re`(?s)if.x.*break....`)
+		ctrl := newFunction(x)
+		switch ctrl {
+		case 1:
@@ -35,2 +37 @@
-		}
-		if x > 2 {
+		case 2:
@@ -45 +46,10 @@
+func newFunction(x int) int {
+	if x < 10 { //@ loc(multipleCtrl, re`(?s)if.x.*return...next1....`), loc(multipleCtrlNotAllSelected, re`(?s)if.x.*break....`)
+		return 1
+	}
+	if x > 2 {
+		return 2
+	}
+	return 0
+}
+
-- @freeControl6/freecontrol.go --
@@ -48,2 +48,4 @@
-		if x < 10 { //@ loc(ctrlVarExists, re`(?s)if.x.*continue...next2....`)
-			continue //next2
+		ctrl1 := newFunction(x)
+		switch ctrl1 {
+		case 1:
+			continue
@@ -54 +56,7 @@
+func newFunction(x int) int {
+	if x < 10 { //@ loc(ctrlVarExists, re`(?s)if.x.*continue...next2....`)
+		return 1 //next2
+	}
+	return 0
+}
+
-- @freeControl7/freecontrol.go --
@@ -57,2 +57,3 @@
-		if x < 10 { //@ loc(twoReturns, re`(?s)if.x.*return.1....`)
-			return 0
+		i, shouldReturn, ctrl := newFunction(x)
+		if shouldReturn {
+			return i
@@ -60,2 +61,2 @@
-		test := x - 4
-		if test > 2 {
+		switch ctrl {
+		case 1:
@@ -64,3 +65 @@
-		if test == 10 {
-			return 1
-		}
@@ -79 +77,14 @@
+
+func newFunction(x int) (int, bool, int) {
+	if x < 10 { //@ loc(twoReturns, re`(?s)if.x.*return.1....`)
+		return 0, true, 0
+	}
+	test := x - 4
+	if test > 2 {
+		return 0, false, 1
+	}
+	if test == 10 {
+		return 1, true, 0
+	}
+	return 0, false, 0
+}
-- @freeControl8/freecontrol.go --
@@ -68,5 +68,3 @@
-		for range "def" { //@ loc(forWithLabel, re`(?s)for.*outer.........`)
-			if x < 2 {
-				continue
-			}
-			if x > 10 {
+		ctrl := newFunction(x)
+		switch ctrl {
+		case 1:
@@ -74 +72 @@
-			}
@@ -79 +76,12 @@
+
+func newFunction(x int) int {
+	for range "def" { //@ loc(forWithLabel, re`(?s)for.*outer.........`)
+		if x < 2 {
+			continue
+		}
+		if x > 10 {
+			return 1
+		}
+	}
+	return 0
+}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_control_label.txt
================================================
This test verifies the behavior of extract function when the extracted block contains:
- At least one free branch statement
- A labeled branch statement and its label, where the corresponding LabeledStmt
may or may not be an EmptyStmt.
See golang/go#77157

-- flags --
-ignore_extra_diags

-- go.mod --
module mod.test/extract

go 1.18


-- extractwithlabel.go --
package extract

//@codeaction(extractWithLabelAndStmt, "refactor.extract.function", edit=labelAndStmt)
//@codeaction(extractWithLabelOnly, "refactor.extract.function", edit=labelOnly)

func FuncGoTo(a int) {
	for range "abc" {
        if a > 5 { //@ loc(extractWithLabelAndStmt, re`(?s)if.*println.1.`), loc(extractWithLabelOnly, re`(?s)if.*label1:`)
            continue
        }
		if a == 10 {
			goto label1
		}
	label1:
		println(1)
	}
}

-- @labelAndStmt/extractwithlabel.go --
@@ -8 +8,3 @@
-        if a > 5 { //@ loc(extractWithLabelAndStmt, re`(?s)if.*println.1.`), loc(extractWithLabelOnly, re`(?s)if.*label1:`)
+        ctrl := newFunction(a)
+        switch ctrl {
+        case 1:
@@ -11,5 +13 @@
-		if a == 10 {
-			goto label1
-		}
-	label1:
-		println(1)
@@ -19 +16,12 @@
+func newFunction(a int) int {
+	if a > 5 { //@ loc(extractWithLabelAndStmt, re`(?s)if.*println.1.`), loc(extractWithLabelOnly, re`(?s)if.*label1:`)
+		return 1
+	}
+	if a == 10 {
+		goto label1
+	}
+label1:
+	println(1)
+	return 0
+}
+
-- @labelOnly/extractwithlabel.go --
@@ -8 +8,3 @@
-        if a > 5 { //@ loc(extractWithLabelAndStmt, re`(?s)if.*println.1.`), loc(extractWithLabelOnly, re`(?s)if.*label1:`)
+        ctrl := newFunction(a)
+        switch ctrl {
+        case 1:
@@ -11,4 +13 @@
-		if a == 10 {
-			goto label1
-		}
-	label1:
@@ -19 +17,12 @@
+func newFunction(a int) int {
+	if a > 5 { //@ loc(extractWithLabelAndStmt, re`(?s)if.*println.1.`), loc(extractWithLabelOnly, re`(?s)if.*label1:`)
+		return 1
+	}
+	if a == 10 {
+		goto label1
+	}
+label1:
+	;
+	return 0
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_method.txt
================================================
This test exercises function and method extraction.

-- flags --
-ignore_extra_diags

-- basic.go --
package extract

//@codeaction(A_XLessThanYP, "refactor.extract.method", edit=meth1)
//@codeaction(A_XLessThanYP, "refactor.extract.function", edit=func1)
//@codeaction(A_AddP1, "refactor.extract.method", edit=meth2)
//@codeaction(A_AddP1, "refactor.extract.function", edit=func2)
//@codeaction(A_AddP2, "refactor.extract.method", edit=meth3)
//@codeaction(A_AddP2, "refactor.extract.function", edit=func3)
//@codeaction(A_XLessThanY, "refactor.extract.method", edit=meth4)
//@codeaction(A_XLessThanY, "refactor.extract.function", edit=func4)
//@codeaction(A_Add1, "refactor.extract.method", edit=meth5)
//@codeaction(A_Add1, "refactor.extract.function", edit=func5)
//@codeaction(A_Add2, "refactor.extract.method", edit=meth6)
//@codeaction(A_Add2, "refactor.extract.function", edit=func6)

type A struct {
	x int
	y int
}

func (a *A) XLessThanYP() bool {
	return a.x < a.y //@loc(A_XLessThanYP, re`return.*a\.y`)
}

func (a *A) AddP() int {
	sum := a.x + a.y //@loc(A_AddP1, re`sum.*a\.y`)
	return sum       //@loc(A_AddP2, re`return.*?sum`)
}

func (a A) XLessThanY() bool {
	return a.x < a.y //@loc(A_XLessThanY, re`return.*a\.y`)
}

func (a A) Add() int {
	sum := a.x + a.y //@loc(A_Add1, re`sum.*a\.y`)
	return sum       //@loc(A_Add2, re`return.*?sum`)
}

-- @func1/basic.go --
@@ -22 +22 @@
-	return a.x < a.y //@loc(A_XLessThanYP, re`return.*a\.y`)
+	return newFunction(a) //@loc(A_XLessThanYP, re`return.*a\.y`)
@@ -25 +25,4 @@
+func newFunction(a *A) bool {
+	return a.x < a.y
+}
+
-- @func2/basic.go --
@@ -26 +26 @@
-	sum := a.x + a.y //@loc(A_AddP1, re`sum.*a\.y`)
+	sum := newFunction(a) //@loc(A_AddP1, re`sum.*a\.y`)
@@ -30 +30,5 @@
+func newFunction(a *A) int {
+	sum := a.x + a.y
+	return sum
+}
+
-- @func3/basic.go --
@@ -27 +27 @@
-	return sum       //@loc(A_AddP2, re`return.*?sum`)
+	return newFunction(sum)       //@loc(A_AddP2, re`return.*?sum`)
@@ -30 +30,4 @@
+func newFunction(sum int) int {
+	return sum
+}
+
-- @func4/basic.go --
@@ -31 +31 @@
-	return a.x < a.y //@loc(A_XLessThanY, re`return.*a\.y`)
+	return newFunction(a) //@loc(A_XLessThanY, re`return.*a\.y`)
@@ -34 +34,4 @@
+func newFunction(a A) bool {
+	return a.x < a.y
+}
+
-- @func5/basic.go --
@@ -35 +35 @@
-	sum := a.x + a.y //@loc(A_Add1, re`sum.*a\.y`)
+	sum := newFunction(a) //@loc(A_Add1, re`sum.*a\.y`)
@@ -39 +39,5 @@
+func newFunction(a A) int {
+	sum := a.x + a.y
+	return sum
+}
+
-- @func6/basic.go --
@@ -36 +36 @@
-	return sum       //@loc(A_Add2, re`return.*?sum`)
+	return newFunction(sum)       //@loc(A_Add2, re`return.*?sum`)
@@ -39 +39,4 @@
+func newFunction(sum int) int {
+	return sum
+}
+
-- @meth1/basic.go --
@@ -22 +22 @@
-	return a.x < a.y //@loc(A_XLessThanYP, re`return.*a\.y`)
+	return a.newMethod() //@loc(A_XLessThanYP, re`return.*a\.y`)
@@ -25 +25,4 @@
+func (a *A) newMethod() bool {
+	return a.x < a.y
+}
+
-- @meth2/basic.go --
@@ -26 +26 @@
-	sum := a.x + a.y //@loc(A_AddP1, re`sum.*a\.y`)
+	sum := a.newMethod() //@loc(A_AddP1, re`sum.*a\.y`)
@@ -30 +30,5 @@
+func (a *A) newMethod() int {
+	sum := a.x + a.y
+	return sum
+}
+
-- @meth3/basic.go --
@@ -27 +27 @@
-	return sum       //@loc(A_AddP2, re`return.*?sum`)
+	return a.newMethod(sum)       //@loc(A_AddP2, re`return.*?sum`)
@@ -30 +30,4 @@
+func (*A) newMethod(sum int) int {
+	return sum
+}
+
-- @meth4/basic.go --
@@ -31 +31 @@
-	return a.x < a.y //@loc(A_XLessThanY, re`return.*a\.y`)
+	return a.newMethod() //@loc(A_XLessThanY, re`return.*a\.y`)
@@ -34 +34,4 @@
+func (a A) newMethod() bool {
+	return a.x < a.y
+}
+
-- @meth5/basic.go --
@@ -35 +35 @@
-	sum := a.x + a.y //@loc(A_Add1, re`sum.*a\.y`)
+	sum := a.newMethod() //@loc(A_Add1, re`sum.*a\.y`)
@@ -39 +39,5 @@
+func (a A) newMethod() int {
+	sum := a.x + a.y
+	return sum
+}
+
-- @meth6/basic.go --
@@ -36 +36 @@
-	return sum       //@loc(A_Add2, re`return.*?sum`)
+	return a.newMethod(sum)       //@loc(A_Add2, re`return.*?sum`)
@@ -39 +39,4 @@
+func (A) newMethod(sum int) int {
+	return sum
+}
+
-- context.go --
package extract

import (
	"context"
	"testing"
)

//@codeaction(B_AddP, "refactor.extract.method", edit=contextMeth1)
//@codeaction(B_AddP, "refactor.extract.function", edit=contextFunc1)
//@codeaction(B_LongList, "refactor.extract.method", edit=contextMeth2)
//@codeaction(B_LongList, "refactor.extract.function", edit=contextFunc2)
//@codeaction(B_AddPWithB, "refactor.extract.function", edit=contextFuncB)
//@codeaction(B_LongListWithT, "refactor.extract.function", edit=contextFuncT)

type B struct {
	x int
	y int
}
	
func (b *B) AddP(ctx context.Context) (int, error) {
	sum := b.x + b.y
	return sum, ctx.Err() //@loc(B_AddP, re`return.*ctx\.Err\(\)`)
}

func (b *B) LongList(ctx context.Context) (int, error) {
	p1 := 1
	p2 := 1
	p3 := 1
	return p1 + p2 + p3, ctx.Err() //@loc(B_LongList, re`return.*ctx\.Err\(\)`)
}

func (b *B) AddPWithB(ctx context.Context, tB *testing.B) (int, error) {
	sum := b.x + b.y //@loc(B_AddPWithB, re`(?s:^.*?Err\(\))`)
	tB.Skip()
	return sum, ctx.Err()
}

func (b *B) LongListWithT(ctx context.Context, t *testing.T) (int, error) {
	p1 := 1
	p2 := 1
	p3 := 1
	p4 := p1 + p2 //@loc(B_LongListWithT, re`(?s:^.*?Err\(\))`)
	t.Skip()
	return p4 + p3, ctx.Err()
}
-- @contextMeth1/context.go --
@@ -22 +22 @@
-	return sum, ctx.Err() //@loc(B_AddP, re`return.*ctx\.Err\(\)`)
+	return b.newMethod(ctx, sum) //@loc(B_AddP, re`return.*ctx\.Err\(\)`)
@@ -25 +25,4 @@
+func (*B) newMethod(ctx context.Context, sum int) (int, error) {
+	return sum, ctx.Err()
+}
+
-- @contextMeth2/context.go --
@@ -29 +29 @@
-	return p1 + p2 + p3, ctx.Err() //@loc(B_LongList, re`return.*ctx\.Err\(\)`)
+	return b.newMethod(ctx, p1, p2, p3) //@loc(B_LongList, re`return.*ctx\.Err\(\)`)
@@ -32 +32,4 @@
+func (*B) newMethod(ctx context.Context, p1 int, p2 int, p3 int) (int, error) {
+	return p1 + p2 + p3, ctx.Err()
+}
+
-- @contextFunc2/context.go --
@@ -29 +29 @@
-	return p1 + p2 + p3, ctx.Err() //@loc(B_LongList, re`return.*ctx\.Err\(\)`)
+	return newFunction(ctx, p1, p2, p3) //@loc(B_LongList, re`return.*ctx\.Err\(\)`)
@@ -32 +32,4 @@
+func newFunction(ctx context.Context, p1 int, p2 int, p3 int) (int, error) {
+	return p1 + p2 + p3, ctx.Err()
+}
+
-- @contextFunc1/context.go --
@@ -22 +22 @@
-	return sum, ctx.Err() //@loc(B_AddP, re`return.*ctx\.Err\(\)`)
+	return newFunction(ctx, sum) //@loc(B_AddP, re`return.*ctx\.Err\(\)`)
@@ -25 +25,4 @@
+func newFunction(ctx context.Context, sum int) (int, error) {
+	return sum, ctx.Err()
+}
+
-- @contextFuncB/context.go --
@@ -33 +33,4 @@
+	return newFunction(ctx, tB, b)
+}
+
+func newFunction(ctx context.Context, tB *testing.B, b *B) (int, error) {
-- @contextFuncT/context.go --
@@ -42 +42,4 @@
+	return newFunction(ctx, t, p1, p2, p3)
+}
+
+func newFunction(ctx context.Context, t *testing.T, p1 int, p2 int, p3 int) (int, error) {


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_return_err.txt
================================================
This test verifies various behaviors of function extraction when every return statement in the extracted block is an error handling return.

-- go.mod --
module mod.test/extract

go 1.18

-- errhandling.go --
package err_handling
import (
    "encoding/json"
    "fmt"
)

//@codeaction(errHandlingBlk1, "refactor.extract.function", edit=err_handling_1)
//@codeaction(errHandlingBlk2, "refactor.extract.function", edit=err_handling_2)
//@codeaction(errHandlingBlk3, "refactor.extract.function", edit=err_handling_3)
//@codeaction(errHandlingBlk4, "refactor.extract.function", edit=err_handling_4)
//@codeaction(errHandlingBlk5, "refactor.extract.function", edit=err_handling_5)

func Func() error {
	a, err := json.Marshal(0) //@loc(errHandlingBlk1, re`(?s)a.*err1....`)
	if err != nil {
		return fmt.Errorf("1: %w", err)
	}
	b, err1 := json.Marshal(0)
	if err1 != nil {
		return fmt.Errorf("2: %w", err1)
	}
	fmt.Println(string(a), string(b))
	return nil
}

func FuncReturnsInt() (int, error) {
	a, err := json.Marshal(0) //@loc(errHandlingBlk2, re`(?s)a.*err2....`)
	if err != nil {
		return 0, fmt.Errorf("1: %w", err)
	}
	b, err2 := json.Marshal(0)
	if err2 != nil {
		return 1, fmt.Errorf("2: %w", err2)
	}
	fmt.Println(string(a), string(b))
	return 3, nil
}

func FuncHasNilReturns() error {
	if _, err := json.Marshal(0); err != nil { //@loc(errHandlingBlk3, re`(?s)if.*return.nil`)
		return err
	}
	if _, err := json.Marshal(1); err != nil {
		return err
	}
	return nil
}

func FuncHasOtherReturns() ([]byte, error) {
	if a, err := json.Marshal(0); err != nil { //@loc(errHandlingBlk4, re`(?s)if.*Marshal.1.`)
		return a, err
	}
	return json.Marshal(1)
}

func FuncErrNameAlreadyExists(err error) ([]byte, error) {
	if a, err := json.Marshal(0); err != nil { //@loc(errHandlingBlk5, re`(?s)if.*a,.err...`)
		return a, err
	}
	if a, err := json.Marshal(3); err != nil {
		return a, err
	}
	return []byte{}, nil
}

-- @err_handling_1/errhandling.go --
@@ -14 +14,9 @@
+	a, b, err := newFunction()
+	if err != nil {
+		return err
+	}
+	fmt.Println(string(a), string(b))
+	return nil
+}
+
+func newFunction() ([]byte, []byte, error) {
@@ -16 +25 @@
-		return fmt.Errorf("1: %w", err)
+		return nil, nil, fmt.Errorf("1: %w", err)
@@ -20 +29 @@
-		return fmt.Errorf("2: %w", err1)
+		return nil, nil, fmt.Errorf("2: %w", err1)
@@ -22,2 +31 @@
-	fmt.Println(string(a), string(b))
-	return nil
+	return a, b, nil
-- @err_handling_2/errhandling.go --
@@ -27 +27,9 @@
+	a, b, i, err := newFunction()
+	if err != nil {
+		return i, err
+	}
+	fmt.Println(string(a), string(b))
+	return 3, nil
+}
+
+func newFunction() ([]byte, []byte, int, error) {
@@ -29 +38 @@
-		return 0, fmt.Errorf("1: %w", err)
+		return nil, nil, 0, fmt.Errorf("1: %w", err)
@@ -33 +42 @@
-		return 1, fmt.Errorf("2: %w", err2)
+		return nil, nil, 1, fmt.Errorf("2: %w", err2)
@@ -35,2 +44 @@
-	fmt.Println(string(a), string(b))
-	return 3, nil
+	return a, b, 0, nil
-- @err_handling_3/errhandling.go --
@@ -40 +40,4 @@
+	return newFunction()
+}
+
+func newFunction() error {
-- @err_handling_4/errhandling.go --
@@ -50 +50,4 @@
+	return newFunction()
+}
+
+func newFunction() ([]byte, error) {
-- @err_handling_5/errhandling.go --
@@ -57 +57,8 @@
+	result, err1 := newFunction()
+	if err1 != nil {
+		return result, err1
+	}
+	return []byte{}, nil
+}
+
+func newFunction() ([]byte, error) {
@@ -63 +71 @@
-	return []byte{}, nil
+	return nil, nil


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable-67905.txt
================================================
This test verifies the fix for golang/go#67905: Extract variable from type
switch produces invalid code

-- go.mod --
module mod.test/extract

go 1.18

-- extract_switch.go --
package extract

import (
	"io"
)

func f() io.Reader

func main() {
	switch r := f().(type) { //@codeaction("f()", "refactor.extract.variable", edit=type_switch_func_call)
	default:
		_ = r
	}
}

-- @type_switch_func_call/extract_switch.go --
@@ -10 +10,2 @@
-	switch r := f().(type) { //@codeaction("f()", "refactor.extract.variable", edit=type_switch_func_call)
+	newVar := f()
+	switch r := newVar.(type) { //@codeaction("f()", "refactor.extract.variable", edit=type_switch_func_call)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable-70563.txt
================================================
This test verifies the fix for golang/go#70563: refactor.extract.variable
inserts new statement before the scope of its free symbols.

-- flags --
-ignore_extra_diags

-- inside_else.go --
package extract

func _() {
	if x := 1; true {

	} else if y := x + 1; true { //@codeaction("x + 1", "refactor.extract.variable", err=re"else-if's init has free variable")

	}
}
-- inside_case.go --
package extract

func _() {
	switch x := 1; x {
	case x + 1: //@codeaction("x + 1", "refactor.extract.variable-all", err=re"switch's init has free variable")
		y := x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"switch's init has free variable")
		_ = y
	case 3:
		y := x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"switch's init has free variable")
		_ = y
	}
}
-- parent_if.go --
package extract

func _() {
	if x := 1; x > 0 {
		y = x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"if-statement's init has free variable")
	} else {
		y = x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"if-statement's init has free variable")
	}
}
-- parent_switch.go --
package extract

func _() {
	switch x := 1; x {
	case 1:
		y = x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"switch's init has free variable")
	case 3:
		y = x + 1 //@codeaction("x + 1", "refactor.extract.variable-all", err=re"switch's init has free variable")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable-if.txt
================================================
This test checks the behavior of the 'extract variable/constant' code actions
when the optimal place for the new declaration is within the "if" statement,
like so:

   if x := 1 + 2 or y + y ; true {
   } else if x > 0 {
   }

A future refactor.variable implementation that does this should avoid
using a 'const' declaration, which is not legal at that location.

-- flags --
-ignore_extra_diags

-- a.go --
package a

func constant() {
	if true {
	} else if 1 + 2 > 0 { //@ codeaction("1 + 2", "refactor.extract.constant", edit=constant)
	}
}

func variable(y int) {
	if true {
	} else if y + y > 0 { //@ codeaction("y + y", "refactor.extract.variable", edit=variable)
	}
}

-- @constant/a.go --
@@ -4 +4 @@
+	const newConst = 1 + 2
@@ -5 +6 @@
-	} else if 1 + 2 > 0 { //@ codeaction("1 + 2", "refactor.extract.constant", edit=constant)
+	} else if newConst > 0 { //@ codeaction("1 + 2", "refactor.extract.constant", edit=constant)
-- @variable/a.go --
@@ -10 +10 @@
+	newVar := y + y
@@ -11 +12 @@
-	} else if y + y > 0 { //@ codeaction("y + y", "refactor.extract.variable", edit=variable)
+	} else if newVar > 0 { //@ codeaction("y + y", "refactor.extract.variable", edit=variable)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable-inexact.txt
================================================
This test checks that extract variable/constant permits:
- extraneous whitespace in the selection
- function literals
- pointer dereference expressions
- parenthesized expressions

-- a.go --
package a

func _(ptr *int) {
	var _ = 1 + 2 + 3 //@codeaction("1 + 2 ", "refactor.extract.constant", edit=spaces)
	var _ = func() {} //@codeaction("func() {}", "refactor.extract.variable", edit=funclit)
	var _ = *ptr      //@codeaction("*ptr", "refactor.extract.variable", edit=ptr)
	var _ = (ptr)     //@codeaction("(ptr)", "refactor.extract.variable", edit=paren)
}

-- @spaces/a.go --
@@ -4 +4,2 @@
-	var _ = 1 + 2 + 3 //@codeaction("1 + 2 ", "refactor.extract.constant", edit=spaces)
+	const newConst = 1 + 2
+	var _ = newConst + 3 //@codeaction("1 + 2 ", "refactor.extract.constant", edit=spaces)
-- @funclit/a.go --
@@ -5 +5,2 @@
-	var _ = func() {} //@codeaction("func() {}", "refactor.extract.variable", edit=funclit)
+	newVar := func() {}
+	var _ = newVar //@codeaction("func() {}", "refactor.extract.variable", edit=funclit)
-- @ptr/a.go --
@@ -6 +6,2 @@
-	var _ = *ptr      //@codeaction("*ptr", "refactor.extract.variable", edit=ptr)
+	newVar := *ptr
+	var _ = newVar      //@codeaction("*ptr", "refactor.extract.variable", edit=ptr)
-- @paren/a.go --
@@ -7 +7,2 @@
-	var _ = (ptr)     //@codeaction("(ptr)", "refactor.extract.variable", edit=paren)
+	newVar := (ptr)
+	var _ = newVar     //@codeaction("(ptr)", "refactor.extract.variable", edit=paren)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable-toplevel.txt
================================================
This test checks the behavior of the 'extract variable/constant' code action
at top level (outside any function). See issue #70665.

-- a.go --
package a

const Length = len("hello") + 2 //@codeaction(`len("hello")`, "refactor.extract.constant", edit=lenhello)

var Slice = append([]int{}, 1, 2, 3) //@codeaction("[]int{}", "refactor.extract.variable", edit=sliceliteral)

type SHA256 [32]byte //@codeaction("32", "refactor.extract.constant", edit=arraylen)

func F([2]int) {} //@codeaction("2", "refactor.extract.constant", edit=paramtypearraylen)

-- @lenhello/a.go --
@@ -3 +3,2 @@
-const Length = len("hello") + 2 //@codeaction(`len("hello")`, "refactor.extract.constant", edit=lenhello)
+const newConst = len("hello")
+const Length = newConst + 2 //@codeaction(`len("hello")`, "refactor.extract.constant", edit=lenhello)
-- @sliceliteral/a.go --
@@ -5 +5,2 @@
-var Slice = append([]int{}, 1, 2, 3) //@codeaction("[]int{}", "refactor.extract.variable", edit=sliceliteral)
+var newVar = []int{}
+var Slice = append(newVar, 1, 2, 3) //@codeaction("[]int{}", "refactor.extract.variable", edit=sliceliteral)
-- @arraylen/a.go --
@@ -7 +7,2 @@
-type SHA256 [32]byte //@codeaction("32", "refactor.extract.constant", edit=arraylen)
+const newConst = 32
+type SHA256 [newConst]byte //@codeaction("32", "refactor.extract.constant", edit=arraylen)
-- @paramtypearraylen/a.go --
@@ -9 +9,2 @@
-func F([2]int) {} //@codeaction("2", "refactor.extract.constant", edit=paramtypearraylen)
+const newConst = 2
+func F([newConst]int) {} //@codeaction("2", "refactor.extract.constant", edit=paramtypearraylen)
-- b/b.go --
package b

// Check that package- and file-level name collisions are avoided.

import newVar3 "errors"

var newVar, newVar1, newVar2 any // these names are taken already
var _ = newVar3.New("")
var a, b int
var C = a + b //@codeaction("a + b", "refactor.extract.variable", edit=fresh)

-- @fresh/b/b.go --
@@ -10 +10,2 @@
-var C = a + b //@codeaction("a + b", "refactor.extract.variable", edit=fresh)
+var newVar4 = a + b
+var C = newVar4 //@codeaction("a + b", "refactor.extract.variable", edit=fresh)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable.txt
================================================
This test checks the behavior of the 'extract variable/constant' code action.
See extract_variable_resolve.txt for the same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- flags --
-ignore_extra_diags

-- basic_lit.go --
package extract

func _() {
	var _ = 1 + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
	var _ = 3 + 4 //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
}

-- @basic_lit1/basic_lit.go --
@@ -4 +4,2 @@
-	var _ = 1 + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
+	const newConst = 1
+	var _ = newConst + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
-- @basic_lit2/basic_lit.go --
@@ -5 +5,2 @@
-	var _ = 3 + 4 //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
+	const newConst = 3 + 4
+	var _ = newConst //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
-- func_call.go --
package extract

import "strconv"

func _() {
	x0 := append([]int{}, 1) //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
	str := "1"
	b, err := strconv.Atoi(str) //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
}

-- @func_call1/func_call.go --
@@ -6 +6,2 @@
-	x0 := append([]int{}, 1) //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
+	newVar := append([]int{}, 1)
+	x0 := newVar //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
-- @func_call2/func_call.go --
@@ -8 +8,2 @@
-	b, err := strconv.Atoi(str) //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
+	newVar, newVar1 := strconv.Atoi(str)
+	b, err := newVar, newVar1 //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
-- scope.go --
package extract

import "go/ast"

func _() {
	x0 := 0
	if true {
		y := ast.CompositeLit{} //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
	}
	if true {
		x := !false //@codeaction("!false", "refactor.extract.constant", edit=scope2)
	}
}

-- @scope1/scope.go --
@@ -8 +8,2 @@
-		y := ast.CompositeLit{} //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
+		newVar := ast.CompositeLit{}
+		y := newVar //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
-- @scope2/scope.go --
@@ -11 +11,2 @@
-		x := !false //@codeaction("!false", "refactor.extract.constant", edit=scope2)
+		const newConst = !false
+		x := newConst //@codeaction("!false", "refactor.extract.constant", edit=scope2)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable_all.txt
================================================
This test checks the behavior of the 'replace all occurrences of expression' code action, with resolve support.
See extract_variable_all_resolve.txt for the same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- flags --
-ignore_extra_diags

-- basic_lit.go --
package extract_all

func _() {
	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
}
-- @basic_lit/basic_lit.go --
@@ -4,2 +4,3 @@
-	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
-	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
+	const newConst = 1 + 2
+	var _ = newConst + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
+	var _ = newConst + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
-- nested_scope.go --
package extract_all

func _() {
	newConst1 := 0
	if true {
		x := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
	}
	if true {
		newConst := 0
		if false {
			y := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
		}
	}
	z := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
}
-- @nested_scope/nested_scope.go --
@@ -5 +5 @@
+	const newConst2 = 1 + 2 + 3
@@ -6 +7 @@
-		x := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+		x := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
@@ -11 +12 @@
-			y := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+			y := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
@@ -14 +15 @@
-	z := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+	z := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
-- function_call.go --
package extract_all

import "fmt"

func _() {
	result := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
	if result != "" {
		anotherResult := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
		_ = anotherResult
	}
}
-- @replace_func_call/function_call.go --
@@ -6 +6,2 @@
-	result := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
+	newVar := fmt.Sprintf("%d", 42)
+	result := newVar //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
@@ -8 +9 @@
-		anotherResult := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
+		anotherResult := newVar //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
-- composite_literals.go --
package extract_all

func _() {
	data := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
	processData(data)
	moreData := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
	processData(moreData)
}

func processData(d []int) {}
-- @composite/composite_literals.go --
@@ -4 +4,2 @@
-	data := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
+	newVar := []int{1, 2, 3}
+	data := newVar //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
@@ -6 +7 @@
-	moreData := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
+	moreData := newVar //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
-- selector.go --
package extract_all

type MyStruct struct {
	Value int
}

func _() {
	s := MyStruct{Value: 10}
	v := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
	if v > 0 {
		w := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
		_ = w
	}
}
-- @sel/selector.go --
@@ -9 +9,2 @@
-	v := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
+	newVar := s.Value
+	v := newVar //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
@@ -11 +12 @@
-		w := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
+		w := newVar //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
-- index.go --
package extract_all

func _() {
	arr := []int{1, 2, 3}
	val := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
	val2 := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
}
-- @index/index.go --
@@ -5,2 +5,3 @@
-	val := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
-	val2 := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
+	newVar := arr[0]
+	val := newVar //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
+	val2 := newVar //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
-- slice_expr.go --
package extract_all

func _() {
	data := []int{1, 2, 3, 4, 5}
	part := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
	anotherPart := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
}
-- @slice/slice_expr.go --
@@ -5,2 +5,3 @@
-	part := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
-	anotherPart := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
+	newVar := data[1:3]
+	part := newVar //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
+	anotherPart := newVar //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
-- nested_func.go --
package extract_all

func outer() {
	inner := func() {
		val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
		_ = val
	}
	inner()
	val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
	_ = val
}
-- @nested/nested_func.go --
@@ -4 +4 @@
+	const newConst = 100 + 200
@@ -5 +6 @@
-		val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
+		val := newConst //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
@@ -9 +10 @@
-	val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
+	val := newConst //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
-- switch.go --
package extract_all

func _() {
	value := 2
	switch value {
	case 1:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	case 2:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	default:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	}
}
-- @switch/switch.go --
@@ -5 +5 @@
+	newVar := value * 10
@@ -7 +8 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
@@ -10 +11 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
@@ -13 +14 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
-- switch_single.go --
package extract_all

func _() {
	value := 2
	switch value {
	case 1:
		result := value * 10
		_ = result
	case 2:
		result := value * 10
		_ = result
	default:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
		_ = result
	}
}
-- @switch_single/switch_single.go --
@@ -13 +13,2 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
+		newVar := value * 10
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
-- func_list.go --
package extract_all

func _() {
	x := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket1, edit=func_list)
		b := 1
		return b + a
	} //@loc(closeBracket1, "}")
	y := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket2, edit=func_list)
		b := 1
		return b + a
	}//@loc(closeBracket2, "}")
}
-- @func_list/func_list.go --
@@ -4 +4 @@
-	x := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket1, edit=func_list)
+	newVar := func(a int) int {
@@ -7,5 +7,3 @@
-	} //@loc(closeBracket1, "}")
-	y := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket2, edit=func_list)
-		b := 1
-		return b + a
-	}//@loc(closeBracket2, "}")
+	}
+	x := newVar //@loc(closeBracket1, "}")
+	y := newVar//@loc(closeBracket2, "}")


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable_all_resolve.txt
================================================
This test checks the behavior of the 'replace all occurrences of expression' code action, with resolve support.
See extract_variable_all.txt for the same test without resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": true,
			"resolveSupport": {
				"properties": ["edit"]
			}
		}
	}
}
-- flags --
-ignore_extra_diags

-- basic_lit.go --
package extract_all

func _() {
	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
}
-- @basic_lit/basic_lit.go --
@@ -4,2 +4,3 @@
-	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
-	var _ = 1 + 2 + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
+	const newConst = 1 + 2
+	var _ = newConst + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
+	var _ = newConst + 3 //@codeaction("1 + 2", "refactor.extract.constant-all", edit=basic_lit)
-- nested_scope.go --
package extract_all

func _() {
	newConst1 := 0
	if true {
		x := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
	}
	if true {
		newConst := 0
		if false {
			y := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
		}
	}
	z := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
}
-- @nested_scope/nested_scope.go --
@@ -5 +5 @@
+	const newConst2 = 1 + 2 + 3
@@ -6 +7 @@
-		x := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+		x := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
@@ -11 +12 @@
-			y := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+			y := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
@@ -14 +15 @@
-	z := 1 + 2 + 3 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
+	z := newConst2 //@codeaction("1 + 2 + 3", "refactor.extract.constant-all", edit=nested_scope)
-- function_call.go --
package extract_all

import "fmt"

func _() {
	result := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
	if result != "" {
		anotherResult := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
		_ = anotherResult
	}
}
-- @replace_func_call/function_call.go --
@@ -6 +6,2 @@
-	result := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
+	newVar := fmt.Sprintf("%d", 42)
+	result := newVar //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
@@ -8 +9 @@
-		anotherResult := fmt.Sprintf("%d", 42) //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
+		anotherResult := newVar //@codeaction(`fmt.Sprintf("%d", 42)`, "refactor.extract.variable-all", edit=replace_func_call)
-- composite_literals.go --
package extract_all

func _() {
	data := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
	processData(data)
	moreData := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
	processData(moreData)
}

func processData(d []int) {}
-- @composite/composite_literals.go --
@@ -4 +4,2 @@
-	data := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
+	newVar := []int{1, 2, 3}
+	data := newVar //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
@@ -6 +7 @@
-	moreData := []int{1, 2, 3} //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
+	moreData := newVar //@codeaction("[]int{1, 2, 3}", "refactor.extract.variable-all", edit=composite)
-- selector.go --
package extract_all

type MyStruct struct {
	Value int
}

func _() {
	s := MyStruct{Value: 10}
	v := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
	if v > 0 {
		w := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
		_ = w
	}
}
-- @sel/selector.go --
@@ -9 +9,2 @@
-	v := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
+	newVar := s.Value
+	v := newVar //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
@@ -11 +12 @@
-		w := s.Value //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
+		w := newVar //@codeaction("s.Value", "refactor.extract.variable-all", edit=sel)
-- index.go --
package extract_all

func _() {
	arr := []int{1, 2, 3}
	val := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
	val2 := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
}
-- @index/index.go --
@@ -5,2 +5,3 @@
-	val := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
-	val2 := arr[0] //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
+	newVar := arr[0]
+	val := newVar //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
+	val2 := newVar //@codeaction("arr[0]", "refactor.extract.variable-all", edit=index)
-- slice_expr.go --
package extract_all

func _() {
	data := []int{1, 2, 3, 4, 5}
	part := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
	anotherPart := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
}
-- @slice/slice_expr.go --
@@ -5,2 +5,3 @@
-	part := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
-	anotherPart := data[1:3] //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
+	newVar := data[1:3]
+	part := newVar //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
+	anotherPart := newVar //@codeaction("data[1:3]", "refactor.extract.variable-all", edit=slice)
-- nested_func.go --
package extract_all

func outer() {
	inner := func() {
		val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
		_ = val
	}
	inner()
	val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
	_ = val
}
-- @nested/nested_func.go --
@@ -4 +4 @@
+	const newConst = 100 + 200
@@ -5 +6 @@
-		val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
+		val := newConst //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
@@ -9 +10 @@
-	val := 100 + 200 //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
+	val := newConst //@codeaction("100 + 200", "refactor.extract.constant-all", edit=nested)
-- switch.go --
package extract_all

func _() {
	value := 2
	switch value {
	case 1:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	case 2:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	default:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
		_ = result
	}
}
-- @switch/switch.go --
@@ -5 +5 @@
+	newVar := value * 10
@@ -7 +8 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
@@ -10 +11 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
@@ -13 +14 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable-all", edit=switch)
-- switch_single.go --
package extract_all

func _() {
	value := 2
	switch value {
	case 1:
		result := value * 10
		_ = result
	case 2:
		result := value * 10
		_ = result
	default:
		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
		_ = result
	}
}
-- @switch_single/switch_single.go --
@@ -13 +13,2 @@
-		result := value * 10 //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
+		newVar := value * 10
+		result := newVar //@codeaction("value * 10", "refactor.extract.variable", edit=switch_single)
-- func_list.go --
package extract_all

func _() {
	x := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket1, edit=func_list)
		b := 1
		return b + a
	} //@loc(closeBracket1, "}")
	y := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket2, edit=func_list)
		b := 1
		return b + a
	}//@loc(closeBracket2, "}")
}
-- @func_list/func_list.go --
@@ -4 +4 @@
-	x := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket1, edit=func_list)
+	newVar := func(a int) int {
@@ -7,5 +7,3 @@
-	} //@loc(closeBracket1, "}")
-	y := func(a int) int { //@codeaction("func", "refactor.extract.variable-all", end=closeBracket2, edit=func_list)
-		b := 1
-		return b + a
-	}//@loc(closeBracket2, "}")
+	}
+	x := newVar //@loc(closeBracket1, "}")
+	y := newVar//@loc(closeBracket2, "}")


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extract_variable_resolve.txt
================================================
This test checks the behavior of the 'extract variable/constant' code action, with resolve support.
See extract_variable.txt for the same test without resolve support.

-- flags --
-ignore_extra_diags

-- basic_lit.go --
package extract

func _() {
	var _ = 1 + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
	var _ = 3 + 4 //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
}

-- @basic_lit1/basic_lit.go --
@@ -4 +4,2 @@
-	var _ = 1 + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
+	const newConst = 1
+	var _ = newConst + 2 //@codeaction("1", "refactor.extract.constant", edit=basic_lit1)
-- @basic_lit2/basic_lit.go --
@@ -5 +5,2 @@
-	var _ = 3 + 4 //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
+	const newConst = 3 + 4
+	var _ = newConst //@codeaction("3 + 4", "refactor.extract.constant", edit=basic_lit2)
-- func_call.go --
package extract

import "strconv"

func _() {
	x0 := append([]int{}, 1) //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
	str := "1"
	b, err := strconv.Atoi(str) //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
}

-- @func_call1/func_call.go --
@@ -6 +6,2 @@
-	x0 := append([]int{}, 1) //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
+	newVar := append([]int{}, 1)
+	x0 := newVar //@codeaction("append([]int{}, 1)", "refactor.extract.variable", edit=func_call1)
-- @func_call2/func_call.go --
@@ -8 +8,2 @@
-	b, err := strconv.Atoi(str) //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
+	newVar, newVar1 := strconv.Atoi(str)
+	b, err := newVar, newVar1 //@codeaction("strconv.Atoi(str)", "refactor.extract.variable", edit=func_call2)
-- scope.go --
package extract

import "go/ast"

func _() {
	x0 := 0
	if true {
		y := ast.CompositeLit{} //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
	}
	if true {
		x := !false //@codeaction("!false", "refactor.extract.constant", edit=scope2)
	}
}

-- @scope1/scope.go --
@@ -8 +8,2 @@
-		y := ast.CompositeLit{} //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
+		newVar := ast.CompositeLit{}
+		y := newVar //@codeaction("ast.CompositeLit{}", "refactor.extract.variable", edit=scope1)
-- @scope2/scope.go --
@@ -11 +11,2 @@
-		x := !false //@codeaction("!false", "refactor.extract.constant", edit=scope2)
+		const newConst = !false
+		x := newConst //@codeaction("!false", "refactor.extract.constant", edit=scope2)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/extracttofile.txt
================================================
This test checks the behavior of the 'extract to a new file' code action.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/extracttofile

go 1.18

-- a.go --
package main

// docs
func fn() {} //@codeaction("func", "refactor.extract.toNewFile", edit=function_declaration)

func fn2() {} //@codeaction("fn2", "refactor.extract.toNewFile", edit=only_select_func_name)

func fn3() {} //@codeaction(re`()fn3`, "refactor.extract.toNewFile", edit=zero_width_selection_on_func_name)

// docs
type T int //@codeaction("type", "refactor.extract.toNewFile", edit=type_declaration)

// docs
var V int //@codeaction("var", "refactor.extract.toNewFile", edit=var_declaration)

// docs
const K = "" //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration)

const ( //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration_multiple_specs)
    P = iota
    Q
    R
)

func fnA () {} //@codeaction("func", "refactor.extract.toNewFile", end=mdEnd, result=multiple_declarations)

// unattached comment

func fnB () {} //@loc(mdEnd, "}")

-- @const_declaration_multiple_specs/p.go --
@@ -0,0 +1,7 @@
+package main
+
+const ( //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration_multiple_specs)
+	P = iota
+	Q
+	R
+)
-- @multiple_declarations/fna.go --
package main

func fnA() {} //@codeaction("func", "refactor.extract.toNewFile", end=mdEnd, result=multiple_declarations)

// unattached comment

func fnB() {}
-- @multiple_declarations/a.go --
package main

// docs
func fn() {} //@codeaction("func", "refactor.extract.toNewFile", edit=function_declaration)

func fn2() {} //@codeaction("fn2", "refactor.extract.toNewFile", edit=only_select_func_name)

func fn3() {} //@codeaction(re`()fn3`, "refactor.extract.toNewFile", edit=zero_width_selection_on_func_name)

// docs
type T int //@codeaction("type", "refactor.extract.toNewFile", edit=type_declaration)

// docs
var V int //@codeaction("var", "refactor.extract.toNewFile", edit=var_declaration)

// docs
const K = "" //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration)

const ( //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration_multiple_specs)
    P = iota
    Q
    R
)

//@loc(mdEnd, "}")

-- @const_declaration_multiple_specs/a.go --
@@ -19,6 +19 @@
-const ( //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration_multiple_specs)
-    P = iota
-    Q
-    R
-)
-
-- existing.go --
-- existing2.go --
-- existing2.1.go --
-- b.go --
package main
func existing() {} //@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict)
func existing2() {} //@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict_again)

-- single_import.go --
package main
import "fmt"
func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=single_import)
    fmt.Println()
}

-- multiple_imports.go --
package main
import (
    "fmt"
    "log"
    time1 "time"
)
func init(){
    log.Println()
}
func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=multiple_imports)
    fmt.Println()
}
func g() string{ //@codeaction("func", "refactor.extract.toNewFile", edit=renamed_import)
    return time1.Now().string()
}

-- blank_import.go --
package main
import _ "fmt"
func F() {} //@codeaction("func", "refactor.extract.toNewFile", edit=blank_import)



-- @blank_import/blank_import.go --
@@ -3 +3 @@
-func F() {} //@codeaction("func", "refactor.extract.toNewFile", edit=blank_import)
+//@codeaction("func", "refactor.extract.toNewFile", edit=blank_import)
-- @blank_import/f.go --
@@ -0,0 +1,3 @@
+package main
+
+func F() {}
-- @const_declaration/a.go --
@@ -16,2 +16 @@
-// docs
-const K = "" //@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration)
+//@codeaction("const", "refactor.extract.toNewFile", edit=const_declaration)
-- @const_declaration/k.go --
@@ -0,0 +1,4 @@
+package main
+
+// docs
+const K = ""
-- @file_name_conflict/b.go --
@@ -2 +2 @@
-func existing() {} //@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict)
+//@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict)
-- @file_name_conflict/existing.1.go --
@@ -0,0 +1,3 @@
+package main
+
+func existing() {}
-- @file_name_conflict_again/b.go --
@@ -3 +3 @@
-func existing2() {} //@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict_again)
+//@codeaction("func", "refactor.extract.toNewFile", edit=file_name_conflict_again)
-- @file_name_conflict_again/existing2.2.go --
@@ -0,0 +1,3 @@
+package main
+
+func existing2() {}
-- @function_declaration/a.go --
@@ -3,2 +3 @@
-// docs
-func fn() {} //@codeaction("func", "refactor.extract.toNewFile", edit=function_declaration)
+//@codeaction("func", "refactor.extract.toNewFile", edit=function_declaration)
-- @function_declaration/fn.go --
@@ -0,0 +1,4 @@
+package main
+
+// docs
+func fn() {}
-- @multiple_imports/f.go --
@@ -0,0 +1,9 @@
+package main
+
+import (
+	"fmt"
+)
+
+func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=multiple_imports)
+	fmt.Println()
+}
-- @multiple_imports/multiple_imports.go --
@@ -3 +3 @@
-    "fmt"
+    
@@ -10,3 +10 @@
-func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=multiple_imports)
-    fmt.Println()
-}
-- @only_select_func_name/a.go --
@@ -6 +6 @@
-func fn2() {} //@codeaction("fn2", "refactor.extract.toNewFile", edit=only_select_func_name)
+//@codeaction("fn2", "refactor.extract.toNewFile", edit=only_select_func_name)
-- @only_select_func_name/fn2.go --
@@ -0,0 +1,3 @@
+package main
+
+func fn2() {}
-- @single_import/f.go --
@@ -0,0 +1,9 @@
+package main
+
+import (
+	"fmt"
+)
+
+func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=single_import)
+	fmt.Println()
+}
-- @single_import/single_import.go --
@@ -2,4 +2 @@
-import "fmt"
-func F() { //@codeaction("func", "refactor.extract.toNewFile", edit=single_import)
-    fmt.Println()
-}
-- @type_declaration/a.go --
@@ -10,2 +10 @@
-// docs
-type T int //@codeaction("type", "refactor.extract.toNewFile", edit=type_declaration)
+//@codeaction("type", "refactor.extract.toNewFile", edit=type_declaration)
-- @type_declaration/t.go --
@@ -0,0 +1,4 @@
+package main
+
+// docs
+type T int
-- @var_declaration/a.go --
@@ -13,2 +13 @@
-// docs
-var V int //@codeaction("var", "refactor.extract.toNewFile", edit=var_declaration)
+//@codeaction("var", "refactor.extract.toNewFile", edit=var_declaration)
-- @var_declaration/v.go --
@@ -0,0 +1,4 @@
+package main
+
+// docs
+var V int
-- @zero_width_selection_on_func_name/a.go --
@@ -8 +8 @@
-func fn3() {} //@codeaction(re`()fn3`, "refactor.extract.toNewFile", edit=zero_width_selection_on_func_name)
+//@codeaction(re`()fn3`, "refactor.extract.toNewFile", edit=zero_width_selection_on_func_name)
-- @zero_width_selection_on_func_name/fn3.go --
@@ -0,0 +1,3 @@
+package main
+
+func fn3() {}
-- @renamed_import/g.go --
@@ -0,0 +1,9 @@
+package main
+
+import (
+	time1 "time"
+)
+
+func g() string { //@codeaction("func", "refactor.extract.toNewFile", edit=renamed_import)
+	return time1.Now().string()
+}
-- @renamed_import/multiple_imports.go --
@@ -5 +5 @@
-    time1 "time"
+    
@@ -13,4 +13 @@
-func g() string{ //@codeaction("func", "refactor.extract.toNewFile", edit=renamed_import)
-    return time1.Now().string()
-}
-
-- copyright.go --
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

// docs
const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=copyright)

-- @copyright/c.go --
@@ -0,0 +1,8 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+// docs
+const C = ""
-- @copyright/copyright.go --
@@ -7,2 +7 @@
-// docs
-const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=copyright)
+//@codeaction("const", "refactor.extract.toNewFile", edit=copyright)
-- buildconstraint.go --
//go:build go1.18

package main

// docs
const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=buildconstraint)

-- @buildconstraint/buildconstraint.go --
@@ -5,2 +5 @@
-// docs
-const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=buildconstraint)
+//@codeaction("const", "refactor.extract.toNewFile", edit=buildconstraint)
-- @buildconstraint/c.go --
@@ -0,0 +1,6 @@
+//go:build go1.18
+
+package main
+
+// docs
+const C = ""
-- copyrightandbuildconstraint.go --
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.18

package main

// docs
const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=copyrightandbuildconstraint)
-- @copyrightandbuildconstraint/c.go --
@@ -0,0 +1,10 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build go1.18
+
+package main
+
+// docs
+const C = ""
-- @copyrightandbuildconstraint/copyrightandbuildconstraint.go --
@@ -9,2 +9 @@
-// docs
-const C = "" //@codeaction("const", "refactor.extract.toNewFile", edit=copyrightandbuildconstraint)
+//@codeaction("const", "refactor.extract.toNewFile", edit=copyrightandbuildconstraint)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/failedresolve.txt
================================================
This test checks that failing to produce edits doesn't fail the
codeAction/resolve operation. Instead, we simply return the action
with its command, and let the action fail when its command is applied
(golang/go#75442).

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/failedresolve

go 1.18

-- resolve.go --
package extract

func _() {
	if x := 1; true {

	} else if y := x + 1; true { //@codeaction("x + 1", "refactor.extract.variable", action=act)

	}
}

-- apply.go --
package extract

func _() {
	if x := 1; true {

	} else if y := x + 1; true { //@codeaction("x + 1", "refactor.extract.variable", err=re"cannot find location to insert")

	}
}

-- @act --
{
	"title": "Extract variable",
	"kind": "refactor.extract.variable",
	"command": {
		"title": "Extract variable",
		"command": "gopls.apply_fix",
		"arguments": [
			{
				"Fix": "extract_variable",
				"Location": {
					"uri": "$WORKDIR/resolve.go",
					"range": {
						"start": {
							"line": 5,
							"character": 16
						},
						"end": {
							"line": 5,
							"character": 21
						}
					}
				},
				"ResolveEdits": true
			}
		]
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/fill_struct.txt
================================================
This test checks the behavior of the 'fill struct' code action.
See fill_struct_resolve.txt for same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/fillstruct

go 1.18

-- data/data.go --
package data

type B struct {
	ExportedInt   int
	unexportedInt int
}

-- a.go --
package fillstruct

import (
	"golang.org/lsptests/fillstruct/data"
)

type basicStruct struct {
	foo int
}

var _ = basicStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)

type twoArgStruct struct {
	foo int
	bar string
}

var _ = twoArgStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)

type nestedStruct struct {
	bar   string
	basic basicStruct
}

var _ = nestedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)

var _ = data.B{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
-- @a1/a.go --
@@ -11 +11,3 @@
-var _ = basicStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)
+var _ = basicStruct{
+	foo: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)
-- @a2/a.go --
@@ -18 +18,4 @@
-var _ = twoArgStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)
+var _ = twoArgStruct{
+	foo: 0,
+	bar: "",
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)
-- @a3/a.go --
@@ -25 +25,4 @@
-var _ = nestedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)
+var _ = nestedStruct{
+	bar:   "",
+	basic: basicStruct{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)
-- @a4/a.go --
@@ -27 +27,3 @@
-var _ = data.B{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
+var _ = data.B{
+	ExportedInt: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
-- a2.go --
package fillstruct

type typedStruct struct {
	m  map[string]int
	s  []int
	c  chan int
	c1 <-chan int
	a  [2]string
}

var _ = typedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)

type funStruct struct {
	fn func(i int) int
}

var _ = funStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)

type funStructComplex struct {
	fn func(i int, s string) (string, int)
}

var _ = funStructComplex{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)

type funStructEmpty struct {
	fn func()
}

var _ = funStructEmpty{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)

-- @a21/a2.go --
@@ -11 +11,7 @@
-var _ = typedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)
+var _ = typedStruct{
+	m:  map[string]int{},
+	s:  []int{},
+	c:  make(chan int),
+	c1: make(<-chan int),
+	a:  [2]string{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)
-- @a22/a2.go --
@@ -17 +17,5 @@
-var _ = funStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)
+var _ = funStruct{
+	fn: func(i int) int {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)
-- @a23/a2.go --
@@ -23 +23,5 @@
-var _ = funStructComplex{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)
+var _ = funStructComplex{
+	fn: func(i int, s string) (string, int) {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)
-- @a24/a2.go --
@@ -29 +29,5 @@
-var _ = funStructEmpty{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)
+var _ = funStructEmpty{
+	fn: func() {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)
-- a3.go --
package fillstruct

import (
	"go/ast"
	"go/token"
)

type Foo struct {
	A int
}

type Bar struct {
	X *Foo
	Y *Foo
}

var _ = Bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)

type importedStruct struct {
	m  map[*ast.CompositeLit]ast.Field
	s  []ast.BadExpr
	a  [3]token.Token
	c  chan ast.EmptyStmt
	fn func(ast_decl ast.DeclStmt) ast.Ellipsis
	st ast.CompositeLit
}

var _ = importedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)

type pointerBuiltinStruct struct {
	b *bool
	s *string
	i *int
}

var _ = pointerBuiltinStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)

var _ = []ast.UnaryExpr{
	{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
}

var _ = []ast.UnaryExpr{{}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
-- @a31/a3.go --
@@ -17 +17,4 @@
-var _ = Bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)
+var _ = Bar{
+	X: &Foo{},
+	Y: &Foo{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)
-- @a32/a3.go --
@@ -28 +28,10 @@
-var _ = importedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)
+var _ = importedStruct{
+	m: map[*ast.CompositeLit]ast.Field{},
+	s: []ast.BadExpr{},
+	a: [3]token.Token{},
+	c: make(chan ast.EmptyStmt),
+	fn: func(ast_decl ast.DeclStmt) ast.Ellipsis {
+		panic("TODO")
+	},
+	st: ast.CompositeLit{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)
-- @a33/a3.go --
@@ -36 +36,5 @@
-var _ = pointerBuiltinStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)
+var _ = pointerBuiltinStruct{
+	b: new(bool),
+	s: new(string),
+	i: new(int),
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)
-- @a34/a3.go --
@@ -39 +39,5 @@
-	{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
+	{
+		OpPos: 0,
+		Op:    0,
+		X:     nil,
+	}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
-- @a35/a3.go --
@@ -42 +42,5 @@
-var _ = []ast.UnaryExpr{{}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
+var _ = []ast.UnaryExpr{{
+	OpPos: 0,
+	Op:    0,
+	X:     nil,
+}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
-- a4.go --
package fillstruct

import "go/ast"

type iStruct struct {
	X int
}

type sStruct struct {
	str string
}

type multiFill struct {
	num   int
	strin string
	arr   []int
}

type assignStruct struct {
	n ast.Node
}

func fill() {
	var x int
	var _ = iStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)

	var s string
	var _ = sStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)

	var n int
	_ = []int{}
	if true {
		arr := []int{1, 2}
	}
	var _ = multiFill{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)

	var node *ast.CompositeLit
	var _ = assignStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
}

-- @a41/a4.go --
@@ -25 +25,3 @@
-	var _ = iStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)
+	var _ = iStruct{
+		X: x,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)
-- @a42/a4.go --
@@ -28 +28,3 @@
-	var _ = sStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)
+	var _ = sStruct{
+		str: s,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)
-- @a43/a4.go --
@@ -35 +35,5 @@
-	var _ = multiFill{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)
+	var _ = multiFill{
+		num:   n,
+		strin: s,
+		arr:   []int{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)
-- @a45/a4.go --
@@ -38 +38,3 @@
-	var _ = assignStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
+	var _ = assignStruct{
+		n: node,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
-- fillStruct.go --
package fillstruct

type StructB struct{}

type StructA struct {
	unexportedIntField int
	ExportedIntField   int
	MapA               map[int]string
	Array              []int
	StructB
}

type StructA2 struct {
	B *StructB
}

type StructA3 struct {
	B StructB
}

func fill() {
	a := StructA{}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
	b := StructA2{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
	c := StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
	if true {
		_ = StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
	}
}

-- @fillStruct1/fillStruct.go --
@@ -22 +22,7 @@
-	a := StructA{}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
+	a := StructA{
+		unexportedIntField: 0,
+		ExportedIntField:   0,
+		MapA:               map[int]string{},
+		Array:              []int{},
+		StructB:            StructB{},
+	}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
-- @fillStruct2/fillStruct.go --
@@ -23 +23,3 @@
-	b := StructA2{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
+	b := StructA2{
+		B: &StructB{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
-- @fillStruct3/fillStruct.go --
@@ -24 +24,3 @@
-	c := StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
+	c := StructA3{
+		B: StructB{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
-- @fillStruct4/fillStruct.go --
@@ -26 +26,3 @@
-		_ = StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
+		_ = StructA3{
+			B: StructB{},
+		} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
-- fillStruct_anon.go --
package fillstruct

type StructAnon struct {
	a struct{}
	b map[string]any
	c map[string]struct {
		d int
		e bool
	}
}

func fill() {
	_ := StructAnon{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
}
-- @fillStruct_anon/fillStruct_anon.go --
@@ -13 +13,8 @@
-	_ := StructAnon{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
+	_ := StructAnon{
+		a: struct{}{},
+		b: map[string]any{},
+		c: map[string]struct {
+			d int
+			e bool
+		}{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
-- fillStruct_nested.go --
package fillstruct

type StructB struct {
	StructC
}

type StructC struct {
	unexportedInt int
}

func nested() {
	c := StructB{
		StructC: StructC{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
	}
}

-- @fill_nested/fillStruct_nested.go --
@@ -13 +13,3 @@
-		StructC: StructC{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
+		StructC: StructC{
+			unexportedInt: 0,
+		}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
-- fillStruct_package.go --
package fillstruct

import (
	h2 "net/http"

	"golang.org/lsptests/fillstruct/data"
)

func unexported() {
	a := data.B{}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
	_ = h2.Client{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
}
-- @fillStruct_package1/fillStruct_package.go --
@@ -10 +10,3 @@
-	a := data.B{}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
+	a := data.B{
+		ExportedInt: 0,
+	}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
-- @fillStruct_package2/fillStruct_package.go --
@@ -11 +11,8 @@
-	_ = h2.Client{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
+	_ = h2.Client{
+		Transport: nil,
+		CheckRedirect: func(req *h2.Request, via []*h2.Request) error {
+			panic("TODO")
+		},
+		Jar:     nil,
+		Timeout: 0,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
-- fillStruct_partial.go --
package fillstruct

type StructPartialA struct {
	PrefilledInt int
	UnfilledInt  int
	StructPartialB
}

type StructPartialB struct {
	PrefilledInt int
	UnfilledInt  int
}

func fill() {
	a := StructPartialA{
		PrefilledInt: 5,
	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_partial1)
	b := StructPartialB{
		/* this comment should disappear */
		PrefilledInt: 7, // This comment should be blown away.
		/* As should
		this one */
	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_partial2)
}

-- @fillStruct_partial1/fillStruct_partial.go --
@@ -16 +16,3 @@
-		PrefilledInt: 5,
+		PrefilledInt:   5,
+		UnfilledInt:    0,
+		StructPartialB: StructPartialB{},
-- @fillStruct_partial2/fillStruct_partial.go --
@@ -23 +23 @@
+		UnfilledInt: 0,
-- fillStruct_spaces.go --
package fillstruct

type StructD struct {
	ExportedIntField int
}

func spaces() {
	d := StructD{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
}

-- @fillStruct_spaces/fillStruct_spaces.go --
@@ -8 +8,3 @@
-	d := StructD{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
+	d := StructD{
+		ExportedIntField: 0,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
-- fillStruct_unsafe.go --
package fillstruct

import "unsafe"

type unsafeStruct struct {
	x int
	p unsafe.Pointer
}

func fill() {
	_ := unsafeStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
}

-- @fillStruct_unsafe/fillStruct_unsafe.go --
@@ -11 +11,4 @@
-	_ := unsafeStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
+	_ := unsafeStruct{
+		x: 0,
+		p: nil,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
-- typeparams.go --
package fillstruct

type emptyStructWithTypeParams[A any] struct{}

var _ = emptyStructWithTypeParams[int]{} // no suggested fix

type basicStructWithTypeParams[T any] struct {
	foo T
}

var _ = basicStructWithTypeParams[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)

type twoArgStructWithTypeParams[F, B any] struct {
	foo F
	bar B
}

var _ = twoArgStructWithTypeParams[string, int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)

var _ = twoArgStructWithTypeParams[int, string]{
	bar: "bar",
} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams3)

type nestedStructWithTypeParams struct {
	bar   string
	basic basicStructWithTypeParams[int]
}

var _ = nestedStructWithTypeParams{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)

func _[T any]() {
	type S struct{ t T }
	_ = S{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)

	type P struct{ t *T }
	_ = P{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)

	type Alias[u any] = struct {
		x u
		y *T
	}
	_ = Alias[string]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)

	type Named[u any] struct {
		x u
		y T
	}
	_ = Named[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
}
-- @typeparams1/typeparams.go --
@@ -11 +11,3 @@
-var _ = basicStructWithTypeParams[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)
+var _ = basicStructWithTypeParams[int]{
+	foo: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)
-- @typeparams2/typeparams.go --
@@ -18 +18,4 @@
-var _ = twoArgStructWithTypeParams[string, int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)
+var _ = twoArgStructWithTypeParams[string, int]{
+	foo: "",
+	bar: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)
-- @typeparams3/typeparams.go --
@@ -22 +22 @@
+	foo: 0,
-- @typeparams4/typeparams.go --
@@ -29 +29,4 @@
-var _ = nestedStructWithTypeParams{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)
+var _ = nestedStructWithTypeParams{
+	bar:   "",
+	basic: basicStructWithTypeParams[int]{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)
-- @typeparams5/typeparams.go --
@@ -33 +33,3 @@
-	_ = S{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)
+	_ = S{
+		t: *new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)
-- @typeparams6/typeparams.go --
@@ -36 +36,3 @@
-	_ = P{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)
+	_ = P{
+		t: new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)
-- @typeparams7/typeparams.go --
@@ -42 +42,4 @@
-	_ = Alias[string]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)
+	_ = Alias[string]{
+		x: "",
+		y: new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)
-- @typeparams8/typeparams.go --
@@ -48 +48,4 @@
-	_ = Named[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
+	_ = Named[int]{
+		x: 0,
+		y: *new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
-- issue63921.go --
package fillstruct

// Test for golang/go#63921: fillstruct panicked with invalid fields.
type invalidStruct struct {
  F int
  Undefined
}

func _() {
  // Note: the golden content for issue63921 is empty: fillstruct produces no
  // edits, but does not panic.
  invalidStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=issue63921)
}
-- named/named.go --
package named

type foo struct {}
type aliasFoo = foo

func _() {
	type namedInt int
	type namedString string
	type namedBool bool
	type namedPointer *foo
	type namedSlice []foo
	type namedInterface interface{ Error() string }
	type namedChan chan int
	type namedMap map[string]foo
	type namedSignature func(string) string
	type namedStruct struct{}
	type namedArray [3]foo
	type namedAlias aliasFoo

	type bar struct {
		namedInt namedInt
		namedString namedString
		namedBool namedBool
		namedPointer namedPointer
		namedSlice namedSlice
		namedInterface namedInterface
		namedChan namedChan
		namedMap namedMap
		namedSignature namedSignature
		namedStruct namedStruct
		namedArray namedArray
		namedAlias namedAlias
	}

	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
}
-- @named/named/named.go --
@@ -35 +35,14 @@
-	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
+	bar{
+		namedInt:       0,
+		namedString:    "",
+		namedBool:      false,
+		namedPointer:   nil,
+		namedSlice:     namedSlice{},
+		namedInterface: nil,
+		namedChan:      nil,
+		namedMap:       namedMap{},
+		namedSignature: nil,
+		namedStruct:    namedStruct{},
+		namedArray:     namedArray{},
+		namedAlias:     namedAlias{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
-- alias/alias.go --
package alias

type foo struct {}
type aliasFoo = foo

func _() {
	type aliasInt = int
	type aliasString = string
	type aliasBool = bool
	type aliasPointer = *foo
	type aliasSlice = []foo
	type aliasInterface = interface{ Error() string }
	type aliasChan = chan int
	type aliasMap = map[string]foo
	type aliasSignature = func(string) string
	type aliasStruct = struct{ bar string }
	type aliasArray = [3]foo
	type aliasNamed = foo

	type bar struct {
		aliasInt aliasInt
		aliasString aliasString
		aliasBool aliasBool
		aliasPointer aliasPointer
		aliasSlice aliasSlice
		aliasInterface aliasInterface
		aliasChan aliasChan
		aliasMap aliasMap
		aliasSignature aliasSignature
		aliasStruct aliasStruct
		aliasArray aliasArray
		aliasNamed aliasNamed
	}

	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)
}
-- @alias/alias/alias.go --
@@ -35 +35,14 @@
-	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)
+	bar{
+		aliasInt:       0,
+		aliasString:    "",
+		aliasBool:      false,
+		aliasPointer:   nil,
+		aliasSlice:     aliasSlice{},
+		aliasInterface: nil,
+		aliasChan:      nil,
+		aliasMap:       aliasMap{},
+		aliasSignature: nil,
+		aliasStruct:    aliasStruct{},
+		aliasArray:     aliasArray{},
+		aliasNamed:     aliasNamed{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)
-- preserveformat/preserveformat.go --
package preserveformat

type (
	Node struct {
		Value int
	}
	Graph struct {
		Nodes []*Node `json:""`
		Edges map[*Node]*Node
		Other string
	}
)

func _() {
	_ := &Graph{
		// comments at the start preserved
		Nodes: []*Node{
			{Value: 0}, // comments in the middle preserved
			// between lines
			{Value: 0},
		}, // another comment
		// comment group
		// below
	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=preserveformat)
}
-- @preserveformat/preserveformat/preserveformat.go --
@@ -24 +24,2 @@
+		Edges: map[*Node]*Node{},
+		Other: "",


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/fill_struct_resolve.txt
================================================
This test checks the behavior of the 'fill struct' code action, with resolve support.
See fill_struct.txt for same test without resolve support.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/fillstruct

go 1.18

-- data/data.go --
package data

type B struct {
	ExportedInt   int
	unexportedInt int
}

-- a.go --
package fillstruct

import (
	"golang.org/lsptests/fillstruct/data"
)

type basicStruct struct {
	foo int
}

var _ = basicStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)

type twoArgStruct struct {
	foo int
	bar string
}

var _ = twoArgStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)

type nestedStruct struct {
	bar   string
	basic basicStruct
}

var _ = nestedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)

var _ = data.B{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
-- @a1/a.go --
@@ -11 +11,3 @@
-var _ = basicStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)
+var _ = basicStruct{
+	foo: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a1)
-- @a2/a.go --
@@ -18 +18,4 @@
-var _ = twoArgStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)
+var _ = twoArgStruct{
+	foo: 0,
+	bar: "",
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a2)
-- @a3/a.go --
@@ -25 +25,4 @@
-var _ = nestedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)
+var _ = nestedStruct{
+	bar:   "",
+	basic: basicStruct{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a3)
-- @a4/a.go --
@@ -27 +27,3 @@
-var _ = data.B{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
+var _ = data.B{
+	ExportedInt: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a4)
-- a2.go --
package fillstruct

type typedStruct struct {
	m  map[string]int
	s  []int
	c  chan int
	c1 <-chan int
	a  [2]string
}

var _ = typedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)

type funStruct struct {
	fn func(i int) int
}

var _ = funStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)

type funStructComplex struct {
	fn func(i int, s string) (string, int)
}

var _ = funStructComplex{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)

type funStructEmpty struct {
	fn func()
}

var _ = funStructEmpty{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)

-- @a21/a2.go --
@@ -11 +11,7 @@
-var _ = typedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)
+var _ = typedStruct{
+	m:  map[string]int{},
+	s:  []int{},
+	c:  make(chan int),
+	c1: make(<-chan int),
+	a:  [2]string{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a21)
-- @a22/a2.go --
@@ -17 +17,5 @@
-var _ = funStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)
+var _ = funStruct{
+	fn: func(i int) int {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a22)
-- @a23/a2.go --
@@ -23 +23,5 @@
-var _ = funStructComplex{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)
+var _ = funStructComplex{
+	fn: func(i int, s string) (string, int) {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a23)
-- @a24/a2.go --
@@ -29 +29,5 @@
-var _ = funStructEmpty{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)
+var _ = funStructEmpty{
+	fn: func() {
+		panic("TODO")
+	},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a24)
-- a3.go --
package fillstruct

import (
	"go/ast"
	"go/token"
)

type Foo struct {
	A int
}

type Bar struct {
	X *Foo
	Y *Foo
}

var _ = Bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)

type importedStruct struct {
	m  map[*ast.CompositeLit]ast.Field
	s  []ast.BadExpr
	a  [3]token.Token
	c  chan ast.EmptyStmt
	fn func(ast_decl ast.DeclStmt) ast.Ellipsis
	st ast.CompositeLit
}

var _ = importedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)

type pointerBuiltinStruct struct {
	b *bool
	s *string
	i *int
}

var _ = pointerBuiltinStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)

var _ = []ast.UnaryExpr{
	{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
}

var _ = []ast.UnaryExpr{{}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
-- @a31/a3.go --
@@ -17 +17,4 @@
-var _ = Bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)
+var _ = Bar{
+	X: &Foo{},
+	Y: &Foo{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a31)
-- @a32/a3.go --
@@ -28 +28,10 @@
-var _ = importedStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)
+var _ = importedStruct{
+	m: map[*ast.CompositeLit]ast.Field{},
+	s: []ast.BadExpr{},
+	a: [3]token.Token{},
+	c: make(chan ast.EmptyStmt),
+	fn: func(ast_decl ast.DeclStmt) ast.Ellipsis {
+		panic("TODO")
+	},
+	st: ast.CompositeLit{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a32)
-- @a33/a3.go --
@@ -36 +36,5 @@
-var _ = pointerBuiltinStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)
+var _ = pointerBuiltinStruct{
+	b: new(bool),
+	s: new(string),
+	i: new(int),
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a33)
-- @a34/a3.go --
@@ -39 +39,5 @@
-	{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
+	{
+		OpPos: 0,
+		Op:    0,
+		X:     nil,
+	}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=a34)
-- @a35/a3.go --
@@ -42 +42,5 @@
-var _ = []ast.UnaryExpr{{}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
+var _ = []ast.UnaryExpr{{
+	OpPos: 0,
+	Op:    0,
+	X:     nil,
+}} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a35)
-- a4.go --
package fillstruct

import "go/ast"

type iStruct struct {
	X int
}

type sStruct struct {
	str string
}

type multiFill struct {
	num   int
	strin string
	arr   []int
}

type assignStruct struct {
	n ast.Node
}

func fill() {
	var x int
	var _ = iStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)

	var s string
	var _ = sStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)

	var n int
	_ = []int{}
	if true {
		arr := []int{1, 2}
	}
	var _ = multiFill{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)

	var node *ast.CompositeLit
	var _ = assignStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
}

-- @a41/a4.go --
@@ -25 +25,3 @@
-	var _ = iStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)
+	var _ = iStruct{
+		X: x,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a41)
-- @a42/a4.go --
@@ -28 +28,3 @@
-	var _ = sStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)
+	var _ = sStruct{
+		str: s,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a42)
-- @a43/a4.go --
@@ -35 +35,5 @@
-	var _ = multiFill{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)
+	var _ = multiFill{
+		num:   n,
+		strin: s,
+		arr:   []int{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a43)
-- @a45/a4.go --
@@ -38 +38,3 @@
-	var _ = assignStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
+	var _ = assignStruct{
+		n: node,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=a45)
-- fillStruct.go --
package fillstruct

type StructA struct {
	unexportedIntField int
	ExportedIntField   int
	MapA               map[int]string
	Array              []int
	StructB
}

type StructA2 struct {
	B *StructB
}

type StructA3 struct {
	B StructB
}

func fill() {
	a := StructA{}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
	b := StructA2{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
	c := StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
	if true {
		_ = StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
	}
}

-- @fillStruct1/fillStruct.go --
@@ -20 +20,7 @@
-	a := StructA{}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
+	a := StructA{
+		unexportedIntField: 0,
+		ExportedIntField:   0,
+		MapA:               map[int]string{},
+		Array:              []int{},
+		StructB:            StructB{},
+	}  //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct1)
-- @fillStruct2/fillStruct.go --
@@ -21 +21,3 @@
-	b := StructA2{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
+	b := StructA2{
+		B: &StructB{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct2)
-- @fillStruct3/fillStruct.go --
@@ -22 +22,3 @@
-	c := StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
+	c := StructA3{
+		B: StructB{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct3)
-- @fillStruct4/fillStruct.go --
@@ -24 +24,3 @@
-		_ = StructA3{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
+		_ = StructA3{
+			B: StructB{},
+		} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct4)
-- fillStruct_anon.go --
package fillstruct

type StructAnon struct {
	a struct{}
	b map[string]any
	c map[string]struct {
		d int
		e bool
	}
}

func fill() {
	_ := StructAnon{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
}
-- @fillStruct_anon/fillStruct_anon.go --
@@ -13 +13,8 @@
-	_ := StructAnon{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
+	_ := StructAnon{
+		a: struct{}{},
+		b: map[string]any{},
+		c: map[string]struct {
+			d int
+			e bool
+		}{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_anon)
-- fillStruct_nested.go --
package fillstruct

type StructB struct {
	StructC
}

type StructC struct {
	unexportedInt int
}

func nested() {
	c := StructB{
		StructC: StructC{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
	}
}

-- @fill_nested/fillStruct_nested.go --
@@ -13 +13,3 @@
-		StructC: StructC{}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
+		StructC: StructC{
+			unexportedInt: 0,
+		}, //@codeaction("}", "refactor.rewrite.fillStruct", edit=fill_nested)
-- fillStruct_package.go --
package fillstruct

import (
	h2 "net/http"

	"golang.org/lsptests/fillstruct/data"
)

func unexported() {
	a := data.B{}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
	_ = h2.Client{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
}
-- @fillStruct_package1/fillStruct_package.go --
@@ -10 +10,3 @@
-	a := data.B{}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
+	a := data.B{
+		ExportedInt: 0,
+	}   //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package1)
-- @fillStruct_package2/fillStruct_package.go --
@@ -11 +11,8 @@
-	_ = h2.Client{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
+	_ = h2.Client{
+		Transport: nil,
+		CheckRedirect: func(req *h2.Request, via []*h2.Request) error {
+			panic("TODO")
+		},
+		Jar:     nil,
+		Timeout: 0,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_package2)
-- fillStruct_partial.go --
package fillstruct

type StructPartialA struct {
	PrefilledInt int
	UnfilledInt  int
	StructPartialB
}

type StructPartialB struct {
	PrefilledInt int
	UnfilledInt  int
}

func fill() {
	a := StructPartialA{
		PrefilledInt: 5,
	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_partial1)
	b := StructPartialB{
		/* this comment should be preserved */
		PrefilledInt: 7, // This comment should be preserved.
		/* As should
		this one */
	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_partial2)
}

-- @fillStruct_partial1/fillStruct_partial.go --
@@ -16 +16,3 @@
-		PrefilledInt: 5,
+		PrefilledInt:   5,
+		UnfilledInt:    0,
+		StructPartialB: StructPartialB{},
-- @fillStruct_partial2/fillStruct_partial.go --
@@ -23 +23 @@
+		UnfilledInt: 0,
-- fillStruct_spaces.go --
package fillstruct

type StructD struct {
	ExportedIntField int
}

func spaces() {
	d := StructD{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
}

-- @fillStruct_spaces/fillStruct_spaces.go --
@@ -8 +8,3 @@
-	d := StructD{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
+	d := StructD{
+		ExportedIntField: 0,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_spaces)
-- fillStruct_unsafe.go --
package fillstruct

import "unsafe"

type unsafeStruct struct {
	x int
	p unsafe.Pointer
}

func fill() {
	_ := unsafeStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
}

-- @fillStruct_unsafe/fillStruct_unsafe.go --
@@ -11 +11,4 @@
-	_ := unsafeStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
+	_ := unsafeStruct{
+		x: 0,
+		p: nil,
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=fillStruct_unsafe)
-- typeparams.go --
package fillstruct

type emptyStructWithTypeParams[A any] struct{}

var _ = emptyStructWithTypeParams[int]{} // no suggested fix

type basicStructWithTypeParams[T any] struct {
	foo T
}

var _ = basicStructWithTypeParams[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)

type twoArgStructWithTypeParams[F, B any] struct {
	foo F
	bar B
}

var _ = twoArgStructWithTypeParams[string, int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)

var _ = twoArgStructWithTypeParams[int, string]{
	bar: "bar",
} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams3)

type nestedStructWithTypeParams struct {
	bar   string
	basic basicStructWithTypeParams[int]
}

var _ = nestedStructWithTypeParams{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)

func _[T any]() {
	type S struct{ t T }
	_ = S{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)

	type P struct{ t *T }
	_ = P{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)

	type Alias[u any] = struct {
		x u
		y *T
	}
	_ = Alias[string]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)

	type Named[u any] struct {
		x u
		y T
	}
	_ = Named[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
}
-- @typeparams1/typeparams.go --
@@ -11 +11,3 @@
-var _ = basicStructWithTypeParams[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)
+var _ = basicStructWithTypeParams[int]{
+	foo: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams1)
-- @typeparams2/typeparams.go --
@@ -18 +18,4 @@
-var _ = twoArgStructWithTypeParams[string, int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)
+var _ = twoArgStructWithTypeParams[string, int]{
+	foo: "",
+	bar: 0,
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams2)
-- @typeparams3/typeparams.go --
@@ -22 +22 @@
+	foo: 0,
-- @typeparams4/typeparams.go --
@@ -29 +29,4 @@
-var _ = nestedStructWithTypeParams{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)
+var _ = nestedStructWithTypeParams{
+	bar:   "",
+	basic: basicStructWithTypeParams[int]{},
+} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams4)
-- @typeparams5/typeparams.go --
@@ -33 +33,3 @@
-	_ = S{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)
+	_ = S{
+		t: *new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams5)
-- @typeparams6/typeparams.go --
@@ -36 +36,3 @@
-	_ = P{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)
+	_ = P{
+		t: new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams6)
-- @typeparams7/typeparams.go --
@@ -42 +42,4 @@
-	_ = Alias[string]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)
+	_ = Alias[string]{
+		x: "",
+		y: new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams7)
-- @typeparams8/typeparams.go --
@@ -48 +48,4 @@
-	_ = Named[int]{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
+	_ = Named[int]{
+		x: 0,
+		y: *new(T),
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=typeparams8)
-- issue63921.go --
package fillstruct

// Test for golang/go#63921: fillstruct panicked with invalid fields.
type invalidStruct struct {
  F int
  Undefined
}

func _() {
  // Note: the golden content for issue63921 is empty: fillstruct produces no
  // edits, but does not panic.
  invalidStruct{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=issue63921)
}
-- named/named.go --
package named

type foo struct {}
type aliasFoo = foo

func _() {
	type namedInt int
	type namedString string
	type namedBool bool
	type namedPointer *foo
	type namedSlice []foo
	type namedInterface interface{ Error() string }
	type namedChan chan int
	type namedMap map[string]foo
	type namedSignature func(string) string
	type namedStruct struct{}
	type namedArray [3]foo
	type namedAlias aliasFoo

	type bar struct {
		namedInt namedInt
		namedString namedString
		namedBool namedBool
		namedPointer namedPointer
		namedSlice namedSlice
		namedInterface namedInterface
		namedChan namedChan
		namedMap namedMap
		namedSignature namedSignature
		namedStruct namedStruct
		namedArray namedArray
		namedAlias namedAlias
	}

	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
}
-- @named/named/named.go --
@@ -35 +35,14 @@
-	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
+	bar{
+		namedInt:       0,
+		namedString:    "",
+		namedBool:      false,
+		namedPointer:   nil,
+		namedSlice:     namedSlice{},
+		namedInterface: nil,
+		namedChan:      nil,
+		namedMap:       namedMap{},
+		namedSignature: nil,
+		namedStruct:    namedStruct{},
+		namedArray:     namedArray{},
+		namedAlias:     namedAlias{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=named)
-- alias/alias.go --
package alias

type foo struct {}
type aliasFoo = foo

func _() {
	type aliasInt = int
	type aliasString = string
	type aliasBool = bool
	type aliasPointer = *foo
	type aliasSlice = []foo
	type aliasInterface = interface{ Error() string }
	type aliasChan = chan int
	type aliasMap = map[string]foo
	type aliasSignature = func(string) string
	type aliasStruct = struct{ bar string }
	type aliasArray = [3]foo
	type aliasNamed = foo

	type bar struct {
		aliasInt aliasInt
		aliasString aliasString
		aliasBool aliasBool
		aliasPointer aliasPointer
		aliasSlice aliasSlice
		aliasInterface aliasInterface
		aliasChan aliasChan
		aliasMap aliasMap
		aliasSignature aliasSignature
		aliasStruct aliasStruct
		aliasArray aliasArray
		aliasNamed aliasNamed
	}

	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)
}
-- @alias/alias/alias.go --
@@ -35 +35,14 @@
-	bar{} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)
+	bar{
+		aliasInt:       0,
+		aliasString:    "",
+		aliasBool:      false,
+		aliasPointer:   nil,
+		aliasSlice:     aliasSlice{},
+		aliasInterface: nil,
+		aliasChan:      nil,
+		aliasMap:       aliasMap{},
+		aliasSignature: nil,
+		aliasStruct:    aliasStruct{},
+		aliasArray:     aliasArray{},
+		aliasNamed:     aliasNamed{},
+	} //@codeaction("}", "refactor.rewrite.fillStruct", edit=alias)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/fill_switch.txt
================================================
This test checks the behavior of the 'fill switch' code action.
See fill_switch_resolve.txt for same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}
-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/fillswitch

go 1.18

-- data/data.go --
package data

type TypeB int

const (
  TypeBOne TypeB = iota
  TypeBTwo
  TypeBThree
)

-- a.go --
package fillswitch

import (
	"golang.org/lsptests/fillswitch/data"
)

type typeA int

const (
	typeAOne typeA = iota
	typeATwo
	typeAThree
)

type notification interface {
	isNotification()
}

type notificationOne struct{}

func (notificationOne) isNotification() {}

type notificationTwo struct{}

func (notificationTwo) isNotification() {}

func doSwitch() {
	var b data.TypeB
	switch b {
	case data.TypeBOne: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a1)
	}

	var a typeA
	switch a {
	case typeAThree: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a2)
	}

	var n notification
	switch n.(type) { //@codeaction("{", "refactor.rewrite.fillSwitch", edit=a3)
	}

	switch nt := n.(type) { //@codeaction("{", "refactor.rewrite.fillSwitch", edit=a4)
	}

	var s struct {
		a typeA
	}

	switch s.a {
	case typeAThree: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a5)
	}
}
-- @a1/a.go --
@@ -31 +31,4 @@
+	case data.TypeBThree:
+	case data.TypeBTwo:
+	default:
+		panic(fmt.Sprintf("unexpected data.TypeB: %#v", b))
-- @a2/a.go --
@@ -36 +36,4 @@
+	case typeAOne:
+	case typeATwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.typeA: %#v", a))
-- @a3/a.go --
@@ -40 +40,4 @@
+	case notificationOne:
+	case notificationTwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.notification: %#v", n))
-- @a4/a.go --
@@ -43 +43,4 @@
+	case notificationOne:
+	case notificationTwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.notification: %#v", nt))
-- @a5/a.go --
@@ -51 +51,4 @@
+	case typeAOne:
+	case typeATwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.typeA: %#v", s.a))


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/fill_switch_resolve.txt
================================================
This test checks the behavior of the 'fill switch' code action, with resolve support.
See fill_switch.txt for same test without resolve support.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/fillswitch

go 1.18

-- data/data.go --
package data

type TypeB int

const (
  TypeBOne TypeB = iota
  TypeBTwo
  TypeBThree
)

-- a.go --
package fillswitch

import (
	"golang.org/lsptests/fillswitch/data"
)

type typeA int

const (
	typeAOne typeA = iota
	typeATwo
	typeAThree
)

type notification interface {
	isNotification()
}

type notificationOne struct{}

func (notificationOne) isNotification() {}

type notificationTwo struct{}

func (notificationTwo) isNotification() {}

func doSwitch() {
	var b data.TypeB
	switch b {
	case data.TypeBOne: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a1)
	}

	var a typeA
	switch a {
	case typeAThree: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a2)
	}

	var n notification
	switch n.(type) { //@codeaction("{", "refactor.rewrite.fillSwitch", edit=a3)
	}

	switch nt := n.(type) { //@codeaction("{", "refactor.rewrite.fillSwitch", edit=a4)
	}

	var s struct {
		a typeA
	}

	switch s.a {
	case typeAThree: //@codeaction(":", "refactor.rewrite.fillSwitch", edit=a5)
	}
}
-- @a1/a.go --
@@ -31 +31,4 @@
+	case data.TypeBThree:
+	case data.TypeBTwo:
+	default:
+		panic(fmt.Sprintf("unexpected data.TypeB: %#v", b))
-- @a2/a.go --
@@ -36 +36,4 @@
+	case typeAOne:
+	case typeATwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.typeA: %#v", a))
-- @a3/a.go --
@@ -40 +40,4 @@
+	case notificationOne:
+	case notificationTwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.notification: %#v", n))
-- @a4/a.go --
@@ -43 +43,4 @@
+	case notificationOne:
+	case notificationTwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.notification: %#v", nt))
-- @a5/a.go --
@@ -51 +51,4 @@
+	case typeAOne:
+	case typeATwo:
+	default:
+		panic(fmt.Sprintf("unexpected fillswitch.typeA: %#v", s.a))


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/functionextraction.txt
================================================
This test verifies various behaviors of function extraction.

-- go.mod --
module mod.test/extract

go 1.18

-- basic.go --
package extract

func _() { //@codeaction("{", "refactor.extract.function", end=closeBracket, result=outer)
	a := 1    //@codeaction("a", "refactor.extract.function", end=end, result=inner)
	_ = a + 4 //@loc(end, "4")
} //@loc(closeBracket, "}")

-- @outer/basic.go --
package extract

func _() { //@codeaction("{", "refactor.extract.function", end=closeBracket, result=outer)
	newFunction() //@loc(end, "4")
}

func newFunction() {
	a := 1 //@codeaction("a", "refactor.extract.function", end=end, result=inner)
	_ = a + 4
} //@loc(closeBracket, "}")

-- @inner/basic.go --
package extract

func _() { //@codeaction("{", "refactor.extract.function", end=closeBracket, result=outer)
	newFunction() //@loc(end, "4")
}

func newFunction() {
	a := 1 //@codeaction("a", "refactor.extract.function", end=end, result=inner)
	_ = a + 4
} //@loc(closeBracket, "}")

-- return.go --
package extract

func _() bool {
	x := 1
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=ifend, result=return)
		return true
	} //@loc(ifend, "}")
	return false
}

-- @return/return.go --
package extract

func _() bool {
	x := 1
	b, shouldReturn := newFunction(x)
	if shouldReturn {
		return b
	} //@loc(ifend, "}")
	return false
}

func newFunction(x int) (bool, bool) {
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=ifend, result=return)
		return true, true
	}
	return false, false
}

-- return_nonnested.go --
package extract

func _() bool {
	x := 1 //@codeaction("x", "refactor.extract.function", end=rnnEnd, result=rnn)
	if x == 0 {
		return true
	}
	return false //@loc(rnnEnd, "false")
}

-- @rnn/return_nonnested.go --
package extract

func _() bool {
	return newFunction() //@loc(rnnEnd, "false")
}

func newFunction() bool {
	x := 1 //@codeaction("x", "refactor.extract.function", end=rnnEnd, result=rnn)
	if x == 0 {
		return true
	}
	return false
}

-- return_complex.go --
package extract

import "fmt"

func _() (int, string, error) {
	x := 1
	y := "hello"
	z := "bye" //@codeaction("z", "refactor.extract.function", end=rcEnd, result=rc)
	if y == z {
		return x, y, fmt.Errorf("same")
	} else if false {
		z = "hi"
		return x, z, nil
	} //@loc(rcEnd, "}")
	return x, z, nil
}

-- @rc/return_complex.go --
package extract

import "fmt"

func _() (int, string, error) {
	x := 1
	y := "hello"
	z, i, s, err, shouldReturn := newFunction(y, x)
	if shouldReturn {
		return i, s, err
	} //@loc(rcEnd, "}")
	return x, z, nil
}

func newFunction(y string, x int) (string, int, string, error, bool) {
	z := "bye" //@codeaction("z", "refactor.extract.function", end=rcEnd, result=rc)
	if y == z {
		return "", x, y, fmt.Errorf("same"), true
	} else if false {
		z = "hi"
		return "", x, z, nil, true
	}
	return z, 0, "", nil, false
}

-- return_complex_nonnested.go --
package extract

import "fmt"

func _() (int, string, error) {
	x := 1
	y := "hello"
	z := "bye" //@codeaction("z", "refactor.extract.function", end=rcnnEnd, result=rcnn)
	if y == z {
		return x, y, fmt.Errorf("same")
	} else if false {
		z = "hi"
		return x, z, nil
	}
	return x, z, nil //@loc(rcnnEnd, "nil")
}

-- @rcnn/return_complex_nonnested.go --
package extract

import "fmt"

func _() (int, string, error) {
	x := 1
	y := "hello"
	return newFunction(y, x) //@loc(rcnnEnd, "nil")
}

func newFunction(y string, x int) (int, string, error) {
	z := "bye" //@codeaction("z", "refactor.extract.function", end=rcnnEnd, result=rcnn)
	if y == z {
		return x, y, fmt.Errorf("same")
	} else if false {
		z = "hi"
		return x, z, nil
	}
	return x, z, nil
}

-- return_func_lit.go --
package extract

import "go/ast"

func _() {
	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
		if n == nil { //@codeaction("if", "refactor.extract.function", end=rflEnd, result=rfl)
			return true
		} //@loc(rflEnd, "}")
		return false
	})
}

-- @rfl/return_func_lit.go --
package extract

import "go/ast"

func _() {
	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
		b, shouldReturn := newFunction(n)
		if shouldReturn {
			return b
		} //@loc(rflEnd, "}")
		return false
	})
}

func newFunction(n ast.Node) (bool, bool) {
	if n == nil { //@codeaction("if", "refactor.extract.function", end=rflEnd, result=rfl)
		return true, true
	}
	return false, false
}

-- return_func_lit_nonnested.go --
package extract

import "go/ast"

func _() {
	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
		if n == nil { //@codeaction("if", "refactor.extract.function", end=rflnnEnd, result=rflnn)
			return true
		}
		return false //@loc(rflnnEnd, "false")
	})
}

-- @rflnn/return_func_lit_nonnested.go --
package extract

import "go/ast"

func _() {
	ast.Inspect(ast.NewIdent("a"), func(n ast.Node) bool {
		return newFunction(n) //@loc(rflnnEnd, "false")
	})
}

func newFunction(n ast.Node) bool {
	if n == nil { //@codeaction("if", "refactor.extract.function", end=rflnnEnd, result=rflnn)
		return true
	}
	return false
}

-- return_init.go --
package extract

func _() string {
	x := 1
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=riEnd, result=ri)
		x = 3
		return "a"
	} //@loc(riEnd, "}")
	x = 2
	return "b"
}

-- @ri/return_init.go --
package extract

func _() string {
	x := 1
	s, shouldReturn := newFunction(x)
	if shouldReturn {
		return s
	} //@loc(riEnd, "}")
	x = 2
	return "b"
}

func newFunction(x int) (string, bool) {
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=riEnd, result=ri)
		x = 3
		return "a", true
	}
	return "", false
}

-- return_init_nonnested.go --
package extract

func _() string {
	x := 1
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=rinnEnd, result=rinn)
		x = 3
		return "a"
	}
	x = 2
	return "b" //@loc(rinnEnd, "\"b\"")
}

-- @rinn/return_init_nonnested.go --
package extract

func _() string {
	x := 1
	return newFunction(x) //@loc(rinnEnd, "\"b\"")
}

func newFunction(x int) string {
	if x == 0 { //@codeaction("if", "refactor.extract.function", end=rinnEnd, result=rinn)
		x = 3
		return "a"
	}
	x = 2
	return "b"
}

-- args_returns.go --
package extract

func _() {
	a := 1
	a = 5     //@codeaction("a", "refactor.extract.function", end=araend, result=ara)
	a = a + 2 //@loc(araend, "2")

	b := a * 2 //@codeaction("b", "refactor.extract.function", end=arbend, result=arb)
	_ = b + 4  //@loc(arbend, "4")
}

-- @ara/args_returns.go --
package extract

func _() {
	a := 1
	a = newFunction(a) //@loc(araend, "2")

	b := a * 2 //@codeaction("b", "refactor.extract.function", end=arbend, result=arb)
	_ = b + 4  //@loc(arbend, "4")
}

func newFunction(a int) int {
	a = 5 //@codeaction("a", "refactor.extract.function", end=araend, result=ara)
	a = a + 2
	return a
}

-- @arb/args_returns.go --
package extract

func _() {
	a := 1
	a = 5     //@codeaction("a", "refactor.extract.function", end=araend, result=ara)
	a = a + 2 //@loc(araend, "2")

	newFunction(a)  //@loc(arbend, "4")
}

func newFunction(a int) {
	b := a * 2 //@codeaction("b", "refactor.extract.function", end=arbend, result=arb)
	_ = b + 4
}

-- scope.go --
package extract

func _() {
	newFunction := 1
	a := newFunction //@codeaction("a", "refactor.extract.function", end="newFunction", result=scope)
	_ = a // avoid diagnostic
}

func newFunction1() int {
	return 1
}

var _ = newFunction1

-- @scope/scope.go --
package extract

func _() {
	newFunction := 1
	a := newFunction2(newFunction) //@codeaction("a", "refactor.extract.function", end="newFunction", result=scope)
	_ = a // avoid diagnostic
}

func newFunction2(newFunction int) int {
	a := newFunction
	return a
}

func newFunction1() int {
	return 1
}

var _ = newFunction1

-- smart_initialization.go --
package extract

func _() {
	var a []int
	a = append(a, 2) //@codeaction("a", "refactor.extract.function", end=siEnd, result=si)
	b := 4           //@loc(siEnd, "4")
	a = append(a, b)
}

-- @si/smart_initialization.go --
package extract

func _() {
	var a []int
	a, b := newFunction(a)           //@loc(siEnd, "4")
	a = append(a, b)
}

func newFunction(a []int) ([]int, int) {
	a = append(a, 2) //@codeaction("a", "refactor.extract.function", end=siEnd, result=si)
	b := 4
	return a, b
}

-- smart_return.go --
package extract

func _() {
	var b []int
	var a int
	a = 2 //@codeaction("a", "refactor.extract.function", end=srEnd, result=sr)
	b = []int{}
	b = append(b, a) //@loc(srEnd, ")")
	b[0] = 1
}

-- @sr/smart_return.go --
package extract

func _() {
	var b []int
	var a int
	b = newFunction(a, b) //@loc(srEnd, ")")
	b[0] = 1
}

func newFunction(a int, b []int) []int {
	a = 2 //@codeaction("a", "refactor.extract.function", end=srEnd, result=sr)
	b = []int{}
	b = append(b, a)
	return b
}

-- unnecessary_param.go --
package extract

func _() {
	var b []int
	a := 2 //@codeaction("a", "refactor.extract.function", end=upEnd, result=up)
	b = []int{}
	b = append(b, a) //@loc(upEnd, ")")
	b[0] = 1
	if a == 2 {
		return
	}
}

-- @up/unnecessary_param.go --
package extract

func _() {
	var b []int
	a, b := newFunction(b) //@loc(upEnd, ")")
	b[0] = 1
	if a == 2 {
		return
	}
}

func newFunction(b []int) (int, []int) {
	a := 2 //@codeaction("a", "refactor.extract.function", end=upEnd, result=up)
	b = []int{}
	b = append(b, a)
	return a, b
}

-- comment.go --
package extract

func _() {
	a := /* comment in the middle of a line */ 1 //@codeaction("a", "refactor.extract.function", end=commentEnd, result=comment1)
	// Comment on its own line  //@codeaction("Comment", "refactor.extract.function", end=commentEnd, result=comment2)
	_ = a + 4 //@loc(commentEnd, "4"),codeaction("_", "refactor.extract.function", end=lastComment, result=comment3)
	// Comment right after 3 + 4

	// Comment after with space //@loc(lastComment, "Comment")
}

-- @comment1/comment.go --
package extract

func _() {
	newFunction() //@loc(commentEnd, "4"),codeaction("_", "refactor.extract.function", end=lastComment, result=comment3)
	// Comment right after 3 + 4

	// Comment after with space //@loc(lastComment, "Comment")
}

func newFunction() {
	a := /* comment in the middle of a line */ 1 //@codeaction("a", "refactor.extract.function", end=commentEnd, result=comment1)
	// Comment on its own line  //@codeaction("Comment", "refactor.extract.function", end=commentEnd, result=comment2)
	_ = a + 4
}

-- @comment2/comment.go --
package extract

func _() {
	a := /* comment in the middle of a line */ 1 //@codeaction("a", "refactor.extract.function", end=commentEnd, result=comment1)
	// Comment on its own line  //@codeaction("Comment", "refactor.extract.function", end=commentEnd, result=comment2)
	newFunction(a) //@loc(commentEnd, "4"),codeaction("_", "refactor.extract.function", end=lastComment, result=comment3)
	// Comment right after 3 + 4

	// Comment after with space //@loc(lastComment, "Comment")
}

func newFunction(a int) {
	_ = a + 4
}

-- @comment3/comment.go --
package extract

func _() {
	a := /* comment in the middle of a line */ 1 //@codeaction("a", "refactor.extract.function", end=commentEnd, result=comment1)
	// Comment on its own line  //@codeaction("Comment", "refactor.extract.function", end=commentEnd, result=comment2)
	newFunction(a) //@loc(commentEnd, "4"),codeaction("_", "refactor.extract.function", end=lastComment, result=comment3)
	// Comment right after 3 + 4

	// Comment after with space //@loc(lastComment, "Comment")
}

func newFunction(a int) {
	_ = a + 4
}

-- redefine.go --
package extract

import "strconv"

func _() {
	i, err := strconv.Atoi("1")
	u, err := strconv.Atoi("2") //@codeaction(re`u.*\)`, "refactor.extract.function", result=redefine)
	if i == u || err == nil {
		return
	}
}

-- @redefine/redefine.go --
package extract

import "strconv"

func _() {
	i, err := strconv.Atoi("1")
	u, err := newFunction() //@codeaction(re`u.*\)`, "refactor.extract.function", result=redefine)
	if i == u || err == nil {
		return
	}
}

func newFunction() (int, error) {
	u, err := strconv.Atoi("2")
	return u, err
}

-- anonymousfunc.go --
package extract
import "cmp"
import "slices"

// issue go#64821
func _() {
	var s []string //@codeaction("var", "refactor.extract.function", end=anonEnd, result=anon1)
	slices.SortFunc(s, func(a, b string) int {
		return cmp.Compare(a, b)
	})
	println(s) //@loc(anonEnd, ")")
}

-- @anon1/anonymousfunc.go --
package extract
import "cmp"
import "slices"

// issue go#64821
func _() {
	newFunction() //@loc(anonEnd, ")")
}

func newFunction() {
	var s []string //@codeaction("var", "refactor.extract.function", end=anonEnd, result=anon1)
	slices.SortFunc(s, func(a, b string) int {
		return cmp.Compare(a, b)
	})
	println(s)
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/functionextraction_issue44813.txt
================================================
This test verifies the fix for golang/go#44813: extraction failure when there
are blank identifiers.

-- go.mod --
module mod.test/extract

go 1.18

-- p.go --
package extract

import "fmt"

func main() {
	x := []rune{} //@codeaction("x", "refactor.extract.function", end=end, result=ext)
	s := "HELLO"
	for _, c := range s {
		x = append(x, c)
	} //@loc(end, "}")
	fmt.Printf("%x\n", x)
}

-- @ext/p.go --
package extract

import "fmt"

func main() {
	x := newFunction() //@loc(end, "}")
	fmt.Printf("%x\n", x)
}

func newFunction() []rune {
	x := []rune{} //@codeaction("x", "refactor.extract.function", end=end, result=ext)
	s := "HELLO"
	for _, c := range s {
		x = append(x, c)
	}
	return x
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/functionextraction_issue50851.txt
================================================
This test checks that function extraction moves comments along with the
extracted code.

-- main.go --
package main

type F struct{}

func (f *F) _() {
	println("a")

	println("b") //@ codeaction("print", "refactor.extract.function", end=end, result=result)
	// This line prints the third letter of the alphabet.
	println("c") //@loc(end, ")")

	println("d")
}
-- @result/main.go --
package main

type F struct{}

func (f *F) _() {
	println("a")

	newFunction() //@loc(end, ")")

	println("d")
}

func newFunction() {
	println("b") //@ codeaction("print", "refactor.extract.function", end=end, result=result)
	// This line prints the third letter of the alphabet.
	println("c")
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/functionextraction_issue66289.txt
================================================

-- a.go --
package a

import (
	"fmt"
	"encoding/json"
)

func F() error {
	a, err := json.Marshal(0) //@codeaction("a", "refactor.extract.function", end=endF, result=F)
	if err != nil {
		return fmt.Errorf("1: %w", err)
	}
	b, err := json.Marshal(0)
	if err != nil {
		return fmt.Errorf("2: %w", err)
	} //@loc(endF, "}")
	fmt.Printf("%s %s", a, b)
	return nil
}

-- @F/a.go --
package a

import (
	"fmt"
	"encoding/json"
)

func F() error {
	a, b, err := newFunction()
	if err != nil {
		return err
	} //@loc(endF, "}")
	fmt.Printf("%s %s", a, b)
	return nil
}

func newFunction() ([]byte, []byte, error) {
	a, err := json.Marshal(0) //@codeaction("a", "refactor.extract.function", end=endF, result=F)
	if err != nil {
		return nil, nil, fmt.Errorf("1: %w", err)
	}
	b, err := json.Marshal(0)
	if err != nil {
		return nil, nil, fmt.Errorf("2: %w", err)
	}
	return a, b, nil
}

-- b.go --
package a

import (
	"fmt"
	"math/rand"
)

func G() (x, y int) {
	v := rand.Int() //@codeaction("v", "refactor.extract.function", end=endG, result=G)
	if v < 0 {
		return 1, 2
	}
	if v > 0 {
		return 3, 4
	} //@loc(endG, "}")
	fmt.Println(v)
	return 5, 6
}
-- @G/b.go --
package a

import (
	"fmt"
	"math/rand"
)

func G() (x, y int) {
	v, x1, y1, shouldReturn := newFunction()
	if shouldReturn {
		return x1, y1
	} //@loc(endG, "}")
	fmt.Println(v)
	return 5, 6
}

func newFunction() (int, int, int, bool) {
	v := rand.Int() //@codeaction("v", "refactor.extract.function", end=endG, result=G)
	if v < 0 {
		return 0, 1, 2, true
	}
	if v > 0 {
		return 0, 3, 4, true
	}
	return v, 0, 0, false
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/functionextraction_issue73972.txt
================================================
This test verifies the fix for golang/go#73972: extraction should
not modify the return statements of anonymous functions.

-- go.mod --
module mod.test/extract

go 1.18

-- a.go --
package extract

import (
    "fmt"
    "strings"
)

func main() {
	b := strings.ContainsFunc("a", func(_ rune) bool { //@codeaction("b", "refactor.extract.function", end=end, result=ext)
		return false
	})
	if b {
		return
	} //@loc(end, "}")
	fmt.Println(b)
}

-- @ext/a.go --
package extract

import (
    "fmt"
    "strings"
)

func main() {
	b, shouldReturn := newFunction()
	if shouldReturn {
		return
	} //@loc(end, "}")
	fmt.Println(b)
}

func newFunction() (bool, bool) {
	b := strings.ContainsFunc("a", func(_ rune) bool { //@codeaction("b", "refactor.extract.function", end=end, result=ext)
		return false
	})
	if b {
		return false, true
	}
	return b, false
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/grouplines.txt
================================================
This test exercises the refactoring of putting arguments, return values, and composite literal elements into a
single line.

-- go.mod --
module unused.mod

go 1.18

-- func_arg/func_arg.go --
package func_arg

func A(
	a string,
	b, c int64,
	x int /*@codeaction("x", "refactor.rewrite.joinLines", result=func_arg)*/,
	y int,
) (r1 string, r2, r3 int64, r4 int, r5 int) {
	return a, b, c, x, y
}

-- @func_arg/func_arg/func_arg.go --
package func_arg

func A(a string, b, c int64, x int /*@codeaction("x", "refactor.rewrite.joinLines", result=func_arg)*/, y int) (r1 string, r2, r3 int64, r4 int, r5 int) {
	return a, b, c, x, y
}

-- func_ret/func_ret.go --
package func_ret

func A(a string, b, c int64, x int, y int) (
	r1 string /*@codeaction("r1", "refactor.rewrite.joinLines", result=func_ret)*/,
	r2, r3 int64,
	r4 int,
	r5 int,
) {
	return a, b, c, x, y
}

-- @func_ret/func_ret/func_ret.go --
package func_ret

func A(a string, b, c int64, x int, y int) (r1 string /*@codeaction("r1", "refactor.rewrite.joinLines", result=func_ret)*/, r2, r3 int64, r4 int, r5 int) {
	return a, b, c, x, y
}

-- functype_arg/functype_arg.go --
package functype_arg

type A func(
	a string,
	b, c int64,
	x int /*@codeaction("x", "refactor.rewrite.joinLines", result=functype_arg)*/,
	y int,
) (r1 string, r2, r3 int64, r4 int, r5 int)

-- @functype_arg/functype_arg/functype_arg.go --
package functype_arg

type A func(a string, b, c int64, x int /*@codeaction("x", "refactor.rewrite.joinLines", result=functype_arg)*/, y int) (r1 string, r2, r3 int64, r4 int, r5 int)

-- functype_ret/functype_ret.go --
package functype_ret

type A func(a string, b, c int64, x int, y int) (
	r1 string /*@codeaction("r1", "refactor.rewrite.joinLines", result=functype_ret)*/,
	r2, r3 int64,
	r4 int,
	r5 int,
)

-- @functype_ret/functype_ret/functype_ret.go --
package functype_ret

type A func(a string, b, c int64, x int, y int) (r1 string /*@codeaction("r1", "refactor.rewrite.joinLines", result=functype_ret)*/, r2, r3 int64, r4 int, r5 int)

-- func_call/func_call.go --
package func_call

import "fmt"

func F() {
	fmt.Println(
		1 /*@codeaction("1", "refactor.rewrite.joinLines", result=func_call)*/,
		2,
		3,
		fmt.Sprintf("hello %d", 4),
	)
}

-- @func_call/func_call/func_call.go --
package func_call

import "fmt"

func F() {
	fmt.Println(1 /*@codeaction("1", "refactor.rewrite.joinLines", result=func_call)*/, 2, 3, fmt.Sprintf("hello %d", 4))
}

-- indent/indent.go --
package indent

import "fmt"

func F() {
	fmt.Println(
        1,
        2,
        3,
        fmt.Sprintf(
            "hello %d" /*@codeaction("hello", "refactor.rewrite.joinLines", result=indent)*/,
            4,
        ))
}

-- @indent/indent/indent.go --
package indent

import "fmt"

func F() {
	fmt.Println(
        1,
        2,
        3,
        fmt.Sprintf("hello %d" /*@codeaction("hello", "refactor.rewrite.joinLines", result=indent)*/, 4))
}

-- structelts/structelts.go --
package structelts

type A struct{
	a int
	b int
}

func F() {
	_ = A{
		a: 1,
		b: 2 /*@codeaction("b", "refactor.rewrite.joinLines", result=structelts)*/,
	}
}

-- @structelts/structelts/structelts.go --
package structelts

type A struct{
	a int
	b int
}

func F() {
	_ = A{a: 1, b: 2 /*@codeaction("b", "refactor.rewrite.joinLines", result=structelts)*/}
}

-- sliceelts/sliceelts.go --
package sliceelts

func F() {
	_ = []int{
		1 /*@codeaction("1", "refactor.rewrite.joinLines", result=sliceelts)*/,
		2,
	}
}

-- @sliceelts/sliceelts/sliceelts.go --
package sliceelts

func F() {
	_ = []int{1 /*@codeaction("1", "refactor.rewrite.joinLines", result=sliceelts)*/, 2}
}

-- mapelts/mapelts.go --
package mapelts

func F() {
	_ = map[string]int{
		"a": 1 /*@codeaction("1", "refactor.rewrite.joinLines", result=mapelts)*/,
		"b": 2,
	}
}

-- @mapelts/mapelts/mapelts.go --
package mapelts

func F() {
	_ = map[string]int{"a": 1 /*@codeaction("1", "refactor.rewrite.joinLines", result=mapelts)*/, "b": 2}
}

-- starcomment/starcomment.go --
package starcomment

func A(
	/*1*/ x /*2*/ string /*3*/ /*@codeaction("x", "refactor.rewrite.joinLines", result=starcomment)*/,
	/*4*/ y /*5*/ int /*6*/,
) (string, int) {
	return x, y
}

-- @starcomment/starcomment/starcomment.go --
package starcomment

func A(/*1*/ x /*2*/ string /*3*/ /*@codeaction("x", "refactor.rewrite.joinLines", result=starcomment)*/, /*4*/ y /*5*/ int /*6*/) (string, int) {
	return x, y
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/import-shadows-builtin.txt
================================================
This is a regression test for bug #63592 in "organize imports" whereby
the new imports would shadow predeclared names.

In the original example, the conflict was between predeclared error
type and the unfortunately named package github.com/coreos/etcd/error,
but this example uses a package with the ludicrous name of complex128.

The new behavior is that we will not attempt to import packages
that shadow predeclared names. (Ideally we would do that only if
the predeclared name is actually referenced in the file, which
complex128 happens to be in this example, but that's a trickier
analysis than the internal/imports package is game for.)

The name complex127 works as usual.

-- go.mod --
module example.com
go 1.18

-- complex128/a.go --
package complex128

var V int

-- complex127/a.go --
package complex127

var V int

-- main.go --
package main

import () //@codeaction("import", "source.organizeImports", result=out)

func main() {
	complex128.V() //@diag("V", re"type complex128 has no field")
	complex127.V() //@diag("complex127", re"(undeclared|undefined)")
}

func _() {
	var _ complex128 = 1 + 2i
}
-- @out/main.go --
package main

import "example.com/complex127" //@codeaction("import", "source.organizeImports", result=out)

func main() {
	complex128.V() //@diag("V", re"type complex128 has no field")
	complex127.V() //@diag("complex127", re"(undeclared|undefined)")
}

func _() {
	var _ complex128 = 1 + 2i
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/imports-generated.txt
================================================
This test verifies that the 'source.organizeImports' code action
is offered in generated files (see #73959).

-- go.mod --
module example.com
go 1.21

-- a.go --
// Code generated by me. DO NOT EDIT.

package a //@codeaction("a", "source.organizeImports", result=out)

func _() {
	fmt.Println("hello") //@diag("fmt", re"undefined")
}

-- @out/a.go --
// Code generated by me. DO NOT EDIT.

package a //@codeaction("a", "source.organizeImports", result=out)

import "fmt"

func _() {
	fmt.Println("hello") //@diag("fmt", re"undefined")
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/imports.txt
================================================
This test verifies the behavior of the 'source.organizeImports' code action.

-- go.mod --
module mod.test/imports

go 1.18

-- add.go --
package imports //@codeaction("imports", "source.organizeImports", result=add)

import (
	"fmt"
)

func _() {
	fmt.Println("")
	bytes.NewBuffer(nil) //@diag("bytes", re"(undeclared|undefined)")
}

-- @add/add.go --
package imports //@codeaction("imports", "source.organizeImports", result=add)

import (
	"bytes"
	"fmt"
)

func _() {
	fmt.Println("")
	bytes.NewBuffer(nil) //@diag("bytes", re"(undeclared|undefined)")
}

-- good.go --
package imports //@codeaction("imports", "source.organizeImports", err=re"found 0 CodeActions")

import "fmt"

func _() {
fmt.Println("")
}

-- issue35458.go --





// package doc
package imports //@codeaction("imports", "source.organizeImports", result=issue35458)






func _() {
	println("Hello, world!")
}








-- @issue35458/issue35458.go --
// package doc
package imports //@codeaction("imports", "source.organizeImports", result=issue35458)






func _() {
	println("Hello, world!")
}








-- multi.go --
package imports //@codeaction("imports", "source.organizeImports", result=multi)

import "fmt"

import "bytes" //@diag("\"bytes\"", re"not used")

func _() {
	fmt.Println("")
}

-- @multi/multi.go --
package imports //@codeaction("imports", "source.organizeImports", result=multi)

import "fmt"

//@diag("\"bytes\"", re"not used")

func _() {
	fmt.Println("")
}

-- needs.go --
package imports //@codeaction("package", "source.organizeImports", result=needs)

func goodbye() {
	fmt.Printf("HI") //@diag("fmt", re"(undeclared|undefined)")
	log.Printf("byeeeee") //@diag("log", re"(undeclared|undefined)")
}

-- @needs/needs.go --
package imports //@codeaction("package", "source.organizeImports", result=needs)

import (
	"fmt"
	"log"
)

func goodbye() {
	fmt.Printf("HI") //@diag("fmt", re"(undeclared|undefined)")
	log.Printf("byeeeee") //@diag("log", re"(undeclared|undefined)")
}

-- remove.go --
package imports //@codeaction("package", "source.organizeImports", result=remove)

import (
	"bytes" //@diag("\"bytes\"", re"not used")
	"fmt"
)

func _() {
	fmt.Println("")
}

-- @remove/remove.go --
package imports //@codeaction("package", "source.organizeImports", result=remove)

import (
	"fmt"
)

func _() {
	fmt.Println("")
}

-- removeall.go --
package imports //@codeaction("package", "source.organizeImports", result=removeall)

import (
	"bytes" //@diag("\"bytes\"", re"not used")
	"fmt" //@diag("\"fmt\"", re"not used")

)

func _() {
}

-- @removeall/removeall.go --
package imports //@codeaction("package", "source.organizeImports", result=removeall)

//@diag("\"fmt\"", re"not used")

func _() {
}

-- twolines.go --
package imports
func main()  {} //@codeaction("main", "source.organizeImports", err=re"found 0")


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-lhs-var-method.txt
================================================
We should not offer a code action to inline 'v' where it appears on the
left-hand side of an assignment: method with pointer receiver.

Regression test for issue #75200.

-- go.mod --
module example.com/a
go 1.18

-- c/c.go --
package c

import "fmt"

type V int

func (V) Method() { }

func (*V) PointerMethod() { }

func _() {
    var v V = V(123)
    v = V(13)
    v.Method() //@codeaction("v", "refactor.inline.variable", result=inlineV)
    v.PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    (v).PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    var vptr *V = &v
    vptr.PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptr)
    (vptr).PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptrpar)
    fmt.Println(v, vptr)
}

-- @inlineV/c/c.go --
package c

import "fmt"

type V int

func (V) Method() { }

func (*V) PointerMethod() { }

func _() {
    var v V = V(123)
    v = V(13)
    V(123).Method() //@codeaction("v", "refactor.inline.variable", result=inlineV)
    v.PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    (v).PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    var vptr *V = &v
    vptr.PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptr)
    (vptr).PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptrpar)
    fmt.Println(v, vptr)
}

-- @inlintVptr/c/c.go --
package c

import "fmt"

type V int

func (V) Method() { }

func (*V) PointerMethod() { }

func _() {
    var v V = V(123)
    v = V(13)
    v.Method() //@codeaction("v", "refactor.inline.variable", result=inlineV)
    v.PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    (v).PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    var vptr *V = &v
    (&v).PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptr)
    (vptr).PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptrpar)
    fmt.Println(v, vptr)
}

-- @inlintVptrpar/c/c.go --
package c

import "fmt"

type V int

func (V) Method() { }

func (*V) PointerMethod() { }

func _() {
    var v V = V(123)
    v = V(13)
    v.Method() //@codeaction("v", "refactor.inline.variable", result=inlineV)
    v.PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    (v).PointerMethod() //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    var vptr *V = &v
    vptr.PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptr)
    (&v).PointerMethod() //@codeaction("vptr", "refactor.inline.variable", result=inlintVptrpar)
    fmt.Println(v, vptr)
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-lhs-var.txt
================================================
We should not offer a code action to inline 'v' where it appears on the
left-hand side of an assignment

Regression test for issue #75200.

-- go.mod --
module example.com/a
go 1.18

-- c/c.go --
package c

import "fmt"

func _() {
    v := 13
    v = 78 //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")

    v += 78 //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    v -= 78 //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    v *= 78 //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")

    v++ //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    v-- //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")

    fmt.Println(v)

    x := &v //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    x = (&v) //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")
    x = &(v) //@codeaction("v", "refactor.inline.variable", err="0 CodeActions of kind refactor.inline.variable")

    fmt.Println(x)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-var-74347.txt
================================================
This is a regression test of a crash in refactor.inline.variable.

-- go.mod --
module example.com/a
go 1.18

-- a/a.go --
package a

func _() {
       x := func(notfree int) { _ = notfree }
       println(x) //@codeaction("x", "refactor.inline.variable", result=out)
}
-- @out/a/a.go --
package a

func _() {
       x := func(notfree int) { _ = notfree }
       println(func(notfree int) { _ = notfree }) //@codeaction("x", "refactor.inline.variable", result=out)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-var-74347b.txt
================================================
This is regression test of a second crash in
refactor.inline.variable covered by #74347.

-- go.mod --
module example.com/a
go 1.18

-- a/a.go --
package a

func _() {
	type S struct{ F int }
	x := S{F: 0}
	_ = x //@codeaction("x", "refactor.inline.variable", result=out)
}

-- @out/a/a.go --
package a

func _() {
	type S struct{ F int }
	x := S{F: 0}
	_ = S{F: 0} //@codeaction("x", "refactor.inline.variable", result=out)
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-var-76144.txt
================================================
Regression test for #76144, a panic in refactor.inline.variable.

It was fixed by CL 683535, making it logically a dup of #74347.

-- a/a.go --
package main

type A struct {
	Name string
}

func F(m map[string]A) {
	human := A{
		Name: "foo",
	}
	m["foo"] = human //@codeaction("hu", "refactor.inline.variable", result=out)
}
-- @out/a/a.go --
package main

type A struct {
	Name string
}

func F(m map[string]A) {
	human := A{
		Name: "foo",
	}
	m["foo"] = A{
	Name: "foo",
} //@codeaction("hu", "refactor.inline.variable", result=out)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-var-parens.txt
================================================
Test that refactor.inline.variable adds parens as needed to preserve
operator precedence (go.dev/issue/77381).

-- go.mod --
module example.com/a
go 1.18

-- a/a.go --
package a

func _() {
	x := 3 + 4
	print(x) //@codeaction("x", "refactor.inline.variable", result=one)
	print(2 * x) //@codeaction("x", "refactor.inline.variable", result=two)
}
-- @one/a/a.go --
package a

func _() {
	x := 3 + 4
	print(3 + 4) //@codeaction("x", "refactor.inline.variable", result=one)
	print(2 * x) //@codeaction("x", "refactor.inline.variable", result=two)
}
-- @two/a/a.go --
package a

func _() {
	x := 3 + 4
	print(x) //@codeaction("x", "refactor.inline.variable", result=one)
	print(2 * (3 + 4)) //@codeaction("x", "refactor.inline.variable", result=two)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-var.txt
================================================
This is a test of the refactor.inline.variable code action.

-- go.mod --
module example.com/a
go 1.18

-- a/a.go --
package a

import "fmt"

func _(x int) {
	s := fmt.Sprintf("+%d", x)
	println(s) //@codeaction("s", "refactor.inline.variable", result=inlineS)
}

-- @inlineS/a/a.go --
package a

import "fmt"

func _(x int) {
	s := fmt.Sprintf("+%d", x)
	println(fmt.Sprintf("+%d", x)) //@codeaction("s", "refactor.inline.variable", result=inlineS)
}

-- b/b.go --
package b

import "fmt"

func _(x int) {
	s2 := fmt.Sprintf("+%d", x)
	{
		x := "shadow"
		println(s2, x) //@codeaction("s2", "refactor.inline.variable", err=re`refers to "x".*shadowed.*at line 8`)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline-version.txt
================================================
Test of caller/callee Go version compatibility check (#75726).

-- go.work --
use .
use ./b

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

import "example.com/b"

var _ = b.Add(1, 2) //@ codeaction("Add", "refactor.inline.call", end=")", err=`cannot inline call to b.Add (declared using go1.20) into a file using go1.18`)

-- b/go.mod --
module example.com/b
go 1.20

-- b/b.go --
package b

func Add(x, y int) int { return x + y }


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline.txt
================================================
This is a minimal test of the refactor.inline.call code action, without resolve support.
See inline_resolve.txt for same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- go.mod --
module example.com/codeaction
go 1.18

-- a/a.go --
package a

func _() {
	println(add(1, 2)) //@codeaction("add", "refactor.inline.call", end=")", result=inline)
}

func add(x, y int) int { return x + y }

-- @inline/a/a.go --
package a

func _() {
	println(1 + 2) //@codeaction("add", "refactor.inline.call", end=")", result=inline)
}

func add(x, y int) int { return x + y }



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline_issue67336.txt
================================================
This is the test case from golang/go#67335, where the inlining resulted in bad
formatting.

The __unused__ import results in removal after a subsequent "organize imports" step.

-- go.mod --
module example.com

go 1.20

-- define/my/typ/foo.go --
package typ
type T int

-- some/other/pkg/foo.go --
package pkg
import "context"
import "example.com/define/my/typ"
func Foo(typ.T) context.Context{ return nil }

-- one/more/pkg/foo.go --
package pkg
func Bar() {}

-- to/be/inlined/foo.go --
package inlined

import "context"
import "example.com/some/other/pkg"
import "example.com/define/my/typ"

func Baz(ctx context.Context) context.Context {
	return pkg.Foo(typ.T(5))
}

-- b/c/foo.go --
package c
import (
	"context"
	"example.com/to/be/inlined"
	"example.com/one/more/pkg"
)

const (
	// This is a constant
	SomeConst = 5
)

func _() {
	inlined.Baz(context.TODO()) //@ codeaction("Baz", "refactor.inline.call", result=inline)
	pkg.Bar()
}

-- @inline/b/c/foo.go --
package c
import (
	"context"
	
	"example.com/one/more/pkg"
	pkg0 "example.com/some/other/pkg"
	"example.com/define/my/typ"
)

const (
	// This is a constant
	SomeConst = 5
)

func _() {
	var _ context.Context = context.TODO()
pkg0.Foo(typ.T(5)) //@ codeaction("Baz", "refactor.inline.call", result=inline)
	pkg.Bar()
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline_issue68554.txt
================================================
This test checks that inlining removes unnecessary interface conversions.

-- main.go --
package main

import (
	"fmt"
	"io"
)

func _(d discard) {
	g(d) //@codeaction("g", "refactor.inline.call", result=out)
}

func g(w io.Writer) { fmt.Println(w) }

var _ discard
type discard struct{}
func (discard) Write(p []byte) (int, error) { return len(p), nil }
-- @out/main.go --
package main

import (
	"fmt"
	"io"
)

func _(d discard) {
	fmt.Println(d) //@codeaction("g", "refactor.inline.call", result=out)
}

func g(w io.Writer) { fmt.Println(w) }

var _ discard
type discard struct{}
func (discard) Write(p []byte) (int, error) { return len(p), nil }


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/inline_resolve.txt
================================================
This is a minimal test of the refactor.inline.call code actions, with resolve support.
See inline.txt for same test without resolve support.

-- go.mod --
module example.com/codeaction
go 1.18

-- a/a.go --
package a

func _() {
	println(add(1, 2)) //@codeaction("add", "refactor.inline.call", end=")", result=inline)
}

func add(x, y int) int { return x + y }

-- @inline/a/a.go --
package a

func _() {
	println(1 + 2) //@codeaction("add", "refactor.inline.call", end=")", result=inline)
}

func add(x, y int) int { return x + y }



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/invertif.txt
================================================
This test exercises the 'invert if condition' code action.

-- p.go --
package invertif

import (
	"fmt"
	"os"
)

func Boolean() {
	b := true
	if b { //@codeaction("if b", "refactor.rewrite.invertIf", edit=boolean)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func BooleanFn() {
	if os.IsPathSeparator('X') { //@codeaction("if os.IsPathSeparator('X')", "refactor.rewrite.invertIf", edit=boolean_fn)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

// Note that the comment here jumps to the wrong location.
func DontRemoveParens() {
	a := false
	b := true
	if !(a ||
		b) { //@codeaction("b", "refactor.rewrite.invertIf", edit=dont_remove_parens)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func ElseIf() {
	// No inversion expected when there's not else clause
	if len(os.Args) > 2 {
		fmt.Println("A")
	}

	// No inversion expected for else-if, that would become unreadable
	if len(os.Args) > 2 {
		fmt.Println("A")
	} else if os.Args[0] == "X" { //@codeaction(re"if os.Args.0. == .X.", "refactor.rewrite.invertIf", edit=else_if)
		fmt.Println("B")
	} else {
		fmt.Println("C")
	}
}

func GreaterThan() {
	if len(os.Args) > 2 { //@codeaction("i", "refactor.rewrite.invertIf", edit=greater_than)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func NotBoolean() {
	b := true
	if !b { //@codeaction("if !b", "refactor.rewrite.invertIf", edit=not_boolean)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func RemoveElse() {
	if true { //@codeaction("if true", "refactor.rewrite.invertIf", edit=remove_else)
		fmt.Println("A")
	} else {
		fmt.Println("B")
		return
	}

	fmt.Println("C")
}

func RemoveParens() {
	b := true
	if !(b) { //@codeaction("if", "refactor.rewrite.invertIf", edit=remove_parens)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func Semicolon() {
	if _, err := fmt.Println("x"); err != nil { //@codeaction("if", "refactor.rewrite.invertIf", edit=semicolon)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func SemicolonAnd() {
	if n, err := fmt.Println("x"); err != nil && n > 0 { //@codeaction("f", "refactor.rewrite.invertIf", edit=semicolon_and)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

func SemicolonOr() {
	if n, err := fmt.Println("x"); err != nil || n < 5 { //@codeaction(re"if n, err := fmt.Println..x..; err != nil .. n < 5", "refactor.rewrite.invertIf", edit=semicolon_or)
		fmt.Println("A")
	} else {
		fmt.Println("B")
	}
}

-- @boolean/p.go --
@@ -10,3 +10 @@
-	if b { //@codeaction("if b", "refactor.rewrite.invertIf", edit=boolean)
-		fmt.Println("A")
-	} else {
+	if !b {
@@ -14 +12,2 @@
+	} else { //@codeaction("if b", "refactor.rewrite.invertIf", edit=boolean)
+		fmt.Println("A")
-- @boolean_fn/p.go --
@@ -18,3 +18 @@
-	if os.IsPathSeparator('X') { //@codeaction("if os.IsPathSeparator('X')", "refactor.rewrite.invertIf", edit=boolean_fn)
-		fmt.Println("A")
-	} else {
+	if !os.IsPathSeparator('X') {
@@ -22 +20,2 @@
+	} else { //@codeaction("if os.IsPathSeparator('X')", "refactor.rewrite.invertIf", edit=boolean_fn)
+		fmt.Println("A")
-- @dont_remove_parens/p.go --
@@ -29,4 +29,2 @@
-	if !(a ||
-		b) { //@codeaction("b", "refactor.rewrite.invertIf", edit=dont_remove_parens)
-		fmt.Println("A")
-	} else {
+	if (a ||
+		b) {
@@ -34 +32,2 @@
+	} else { //@codeaction("b", "refactor.rewrite.invertIf", edit=dont_remove_parens)
+		fmt.Println("A")
-- @else_if/p.go --
@@ -46,3 +46 @@
-	} else if os.Args[0] == "X" { //@codeaction(re"if os.Args.0. == .X.", "refactor.rewrite.invertIf", edit=else_if)
-		fmt.Println("B")
-	} else {
+	} else if os.Args[0] != "X" {
@@ -50 +48,2 @@
+	} else { //@codeaction(re"if os.Args.0. == .X.", "refactor.rewrite.invertIf", edit=else_if)
+		fmt.Println("B")
-- @greater_than/p.go --
@@ -54,3 +54 @@
-	if len(os.Args) > 2 { //@codeaction("i", "refactor.rewrite.invertIf", edit=greater_than)
-		fmt.Println("A")
-	} else {
+	if len(os.Args) <= 2 {
@@ -58 +56,2 @@
+	} else { //@codeaction("i", "refactor.rewrite.invertIf", edit=greater_than)
+		fmt.Println("A")
-- @not_boolean/p.go --
@@ -63,3 +63 @@
-	if !b { //@codeaction("if !b", "refactor.rewrite.invertIf", edit=not_boolean)
-		fmt.Println("A")
-	} else {
+	if b {
@@ -67 +65,2 @@
+	} else { //@codeaction("if !b", "refactor.rewrite.invertIf", edit=not_boolean)
+		fmt.Println("A")
-- @remove_else/p.go --
@@ -71,3 +71 @@
-	if true { //@codeaction("if true", "refactor.rewrite.invertIf", edit=remove_else)
-		fmt.Println("A")
-	} else {
+	if false {
@@ -78 +76,3 @@
+	//@codeaction("if true", "refactor.rewrite.invertIf", edit=remove_else)
+	fmt.Println("A")
+
-- @remove_parens/p.go --
@@ -83,3 +83 @@
-	if !(b) { //@codeaction("if", "refactor.rewrite.invertIf", edit=remove_parens)
-		fmt.Println("A")
-	} else {
+	if b {
@@ -87 +85,2 @@
+	} else { //@codeaction("if", "refactor.rewrite.invertIf", edit=remove_parens)
+		fmt.Println("A")
-- @semicolon/p.go --
@@ -91,3 +91 @@
-	if _, err := fmt.Println("x"); err != nil { //@codeaction("if", "refactor.rewrite.invertIf", edit=semicolon)
-		fmt.Println("A")
-	} else {
+	if _, err := fmt.Println("x"); err == nil {
@@ -95 +93,2 @@
+	} else { //@codeaction("if", "refactor.rewrite.invertIf", edit=semicolon)
+		fmt.Println("A")
-- @semicolon_and/p.go --
@@ -99,3 +99 @@
-	if n, err := fmt.Println("x"); err != nil && n > 0 { //@codeaction("f", "refactor.rewrite.invertIf", edit=semicolon_and)
-		fmt.Println("A")
-	} else {
+	if n, err := fmt.Println("x"); err == nil || n <= 0 {
@@ -103 +101,2 @@
+	} else { //@codeaction("f", "refactor.rewrite.invertIf", edit=semicolon_and)
+		fmt.Println("A")
-- @semicolon_or/p.go --
@@ -107,3 +107 @@
-	if n, err := fmt.Println("x"); err != nil || n < 5 { //@codeaction(re"if n, err := fmt.Println..x..; err != nil .. n < 5", "refactor.rewrite.invertIf", edit=semicolon_or)
-		fmt.Println("A")
-	} else {
+	if n, err := fmt.Println("x"); err == nil && n >= 5 {
@@ -111 +109,2 @@
+	} else { //@codeaction(re"if n, err := fmt.Println..x..; err != nil .. n < 5", "refactor.rewrite.invertIf", edit=semicolon_or)
+		fmt.Println("A")


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/issue64558.txt
================================================
Test of an inlining failure due to an ill-typed input program (#64558).

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

func _() {
	f(1, 2) //@ diag("2", re"too many arguments"), codeaction("f", "refactor.inline.call", end=")", err=re`inlining failed \("too many arguments"\), likely because inputs were ill-typed`)
}

func f(int) {}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/issue70268.txt
================================================
This test verifies the remove of unused parameters in case of syntax errors.
Issue golang/go#70268.

-- go.mod --
module unused.mod

go 1.21

-- a/a.go --
package a

func A(x, unused int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- @a/a/a.go --
package a

func A(x int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- b/b.go --
package b

import "unused.mod/a"

func main(){
	a.A/*dsdd*/(/*cccc*/ 1,


	) //@diag(")", re"not enough arguments")
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/moveparam.txt
================================================
This test checks basic functionality of the "move parameter left/right" code
action.

Note that in many of these tests, a permutation can either be expressed as
a parameter move left or right. In these cases, the codeaction assertions
deliberately share the same golden data.

-- go.mod --
module example.com/moveparam

go 1.19

-- basic/basic.go --
package basic

func Foo(a, b int) int { //@codeaction("a", "refactor.rewrite.moveParamRight", result=basic), codeaction("b", "refactor.rewrite.moveParamLeft", result=basic)
	return a + b
}

func _() {
	x, y := 1, 2
	z := Foo(x, y)
	_ = z
}

-- basic/caller/caller.go --
package caller

import "example.com/moveparam/basic"

func a() int { return 1 }
func b() int { return 2 }

// Check that we can refactor a call in a toplevel var decl.
var _ = basic.Foo(1, 2)

// Check that we can refactor a call with effects in a toplevel var decl.
var _ = basic.Foo(a(), b())

func _() {
	// check various refactorings in a function body, and comment handling.
	_ = basic.Foo(1, 2) // with comments
	// another comment
	_ = basic.Foo(3, 4)
	x := 4
	x = basic.Foo(x /* this is an inline comment */, 5)
}

-- @basic/basic/basic.go --
package basic

func Foo(b, a int) int { //@codeaction("a", "refactor.rewrite.moveParamRight", result=basic), codeaction("b", "refactor.rewrite.moveParamLeft", result=basic)
	return a + b
}

func _() {
	x, y := 1, 2
	z := Foo(y, x)
	_ = z
}
-- @basic/basic/caller/caller.go --
package caller

import "example.com/moveparam/basic"

func a() int { return 1 }
func b() int { return 2 }

// Check that we can refactor a call in a toplevel var decl.
var _ = basic.Foo(2, 1)

// Check that we can refactor a call with effects in a toplevel var decl.
var _ = basic.Foo(b(), a())

func _() {
	// check various refactorings in a function body, and comment handling.
	_ = basic.Foo(2, 1) // with comments
	// another comment
	_ = basic.Foo(4, 3)
	x := 4
	x = basic.Foo(5, x)
}
-- method/method.go --
package method

type T struct{}

func (T) Foo(a, b int) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=method), codeaction("b", "refactor.rewrite.moveParamLeft", result=method)

func _() {
	var t T
	t.Foo(1, 2)
	// TODO(rfindley): test method expressions here, once they are handled.
}

-- method/caller/caller.go --
package caller

import "example.com/moveparam/method"

func _() {
	var t method.T
	t.Foo(1, 2)
}

-- @method/method/caller/caller.go --
package caller

import "example.com/moveparam/method"

func _() {
	var t method.T
	t.Foo(2, 1)
}
-- @method/method/method.go --
package method

type T struct{}

func (T) Foo(b, a int) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=method), codeaction("b", "refactor.rewrite.moveParamLeft", result=method)

func _() {
	var t T
	t.Foo(2, 1)
	// TODO(rfindley): test method expressions here, once they are handled.
}
-- fieldlist/joinfield.go --
package fieldlist

func JoinField(a int, b string, c int) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=joinfield), codeaction("b", "refactor.rewrite.moveParamLeft", result=joinfield)

func _() {
	JoinField(1, "2", 3)
}

-- @joinfield/fieldlist/joinfield.go --
package fieldlist

func JoinField(b string, a, c int) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=joinfield), codeaction("b", "refactor.rewrite.moveParamLeft", result=joinfield)

func _() {
	JoinField("2", 1, 3)
}
-- fieldlist/splitfield.go --
package fieldlist

func SplitField(a int, b, c string) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=splitfield), codeaction("b", "refactor.rewrite.moveParamLeft", result=splitfield)

func _() {
	SplitField(1, "2", "3")
}

-- @splitfield/fieldlist/splitfield.go --
package fieldlist

func SplitField(b string, a int, c string) {} //@codeaction("a", "refactor.rewrite.moveParamRight", result=splitfield), codeaction("b", "refactor.rewrite.moveParamLeft", result=splitfield)

func _() {
	SplitField("2", 1, "3")
}
-- unnamed/unnamed.go --
package unnamed

func Unnamed(int, string) { //@codeaction("int", "refactor.rewrite.moveParamRight", result=unnamed)
}

func _() {
	Unnamed(1, "hi")
}
-- @unnamed/unnamed/unnamed.go --
package unnamed

func Unnamed(string, int) { //@codeaction("int", "refactor.rewrite.moveParamRight", result=unnamed)
}

func _() {
	Unnamed("hi", 1)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/moveparam_issue70599.txt
================================================
This test checks the fixes for bugs encountered while bug-bashing on the
movement refactoring.

-- go.mod --
module example.com

go 1.21

-- unnecessaryconversion.go --
package a

// We should not add unnecessary conversions to concrete arguments to concrete
// parameters when the parameter use is in assignment context.

type Hash [32]byte

func Cache(key [32]byte, value any) { //@codeaction("key", "refactor.rewrite.moveParamRight", result=conversion)
	// Not implemented.
}

func _() {
	var k Hash
	Cache(k, 0)
	Cache(Hash{}, 1)
	Cache([32]byte{}, 2)
}

-- @conversion/unnecessaryconversion.go --
package a

// We should not add unnecessary conversions to concrete arguments to concrete
// parameters when the parameter use is in assignment context.

type Hash [32]byte

func Cache(value any, key [32]byte) { //@codeaction("key", "refactor.rewrite.moveParamRight", result=conversion)
	// Not implemented.
}

func _() {
	var k Hash
	Cache(0, k)
	Cache(1, Hash{})
	Cache(2, [32]byte{})
}
-- shortvardecl.go --
package a

func Short(x, y int) (int, int) { //@codeaction("x", "refactor.rewrite.moveParamRight", result=short)
	return x, y
}

func _() {
	x, y := Short(0, 1)
	_, _ = x, y
}

func _() {
	var x, y int
	x, y = Short(0, 1)
	_, _ = x, y
}

func _() {
	_, _ = Short(0, 1)
}
-- @short/shortvardecl.go --
package a

func Short(y, x int) (int, int) { //@codeaction("x", "refactor.rewrite.moveParamRight", result=short)
	return x, y
}

func _() {
	x, y := Short(1, 0)
	_, _ = x, y
}

func _() {
	var x, y int
	x, y = Short(1, 0)
	_, _ = x, y
}

func _() {
	_, _ = Short(1, 0)
}
-- variadic.go --
package a

// We should not offer movement involving variadic parameters if it is not well
// supported.

func Variadic(x int, y ...string) { //@codeaction("x", "refactor.rewrite.moveParamRight", err="0 CodeActions"), codeaction("y", "refactor.rewrite.moveParamLeft", err="0 CodeActions")
}

func _() {
	Variadic(1, "a", "b")
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/remove_struct_tags.txt
================================================
This test checks the behavior of the 'Remove struct tags' code action without dialogs.

-- flags --
-ignore_extra_diags

-- removetags.go --
package removetags

type A struct {
	x int `json:"x"` //@codeaction("x", "refactor.rewrite.removeTags", edit=singleline)
	y int `json:"y"` //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.removeTags", edit=twolines)
	z int `json:"z"` //@codeaction(re`()n`, "refactor.rewrite.removeTags", edit=entirestruct)
}
-- @entirestruct/removetags.go --
@@ -4,3 +4,3 @@
-	x int `json:"x"` //@codeaction("x", "refactor.rewrite.removeTags", edit=singleline)
-	y int `json:"y"` //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.removeTags", edit=twolines)
-	z int `json:"z"` //@codeaction(re`()n`, "refactor.rewrite.removeTags", edit=entirestruct)
+	x int //@codeaction("x", "refactor.rewrite.removeTags", edit=singleline)
+	y int //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.removeTags", edit=twolines)
+	z int //@codeaction(re`()n`, "refactor.rewrite.removeTags", edit=entirestruct)
-- @singleline/removetags.go --
@@ -4 +4 @@
-	x int `json:"x"` //@codeaction("x", "refactor.rewrite.removeTags", edit=singleline)
+	x int //@codeaction("x", "refactor.rewrite.removeTags", edit=singleline)
-- @twolines/removetags.go --
@@ -5,2 +5,2 @@
-	y int `json:"y"` //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.removeTags", edit=twolines)
-	z int `json:"z"` //@codeaction(re`()n`, "refactor.rewrite.removeTags", edit=entirestruct)
+	y int //@codeaction(re`(?s)y.*.z int`, "refactor.rewrite.removeTags", edit=twolines)
+	z int //@codeaction(re`()n`, "refactor.rewrite.removeTags", edit=entirestruct)


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam.txt
================================================
This test exercises the refactoring to remove unused parameters.
See removeparam_resolve.txt for same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- go.mod --
module unused.mod

go 1.18

-- a/a.go --
package a

func A(x, unused int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- @a/a/a.go --
package a

func A(x int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- a/a2.go --
package a

func _() {
	A(1, 2)
}

-- a/a_test.go --
package a

func _() {
	A(1, 2)
}

-- a/a_x_test.go --
package a_test

import "unused.mod/a"

func _() {
	a.A(1, 2)
}

-- b/b.go --
package b

import "unused.mod/a"

func f() int {
	return 1
}

func g() int {
	return 2
}

func _() {
	a.A(f(), 1)
}

var _ = g

-- @a/a/a2.go --
package a

func _() {
	A(1)
}
-- @a/a/a_test.go --
package a

func _() {
	A(1)
}
-- @a/a/a_x_test.go --
package a_test

import "unused.mod/a"

func _() {
	a.A(1)
}
-- @a/b/b.go --
package b

import "unused.mod/a"

func f() int {
	return 1
}

func g() int {
	return 2
}

func _() {
	a.A(f())
}

var _ = g
-- field/field.go --
package field

func Field(x int, field int) { //@codeaction("int", "refactor.rewrite.removeUnusedParam", result=field)
}

func _() {
	Field(1, 2)
}
-- @field/field/field.go --
package field

func Field(field int) { //@codeaction("int", "refactor.rewrite.removeUnusedParam", result=field)
}

func _() {
	Field(2)
}
-- ellipsis/ellipsis.go --
package ellipsis

func Ellipsis(...any) { //@codeaction("any", "refactor.rewrite.removeUnusedParam", result=ellipsis)
}

func _() {
	// TODO(rfindley): investigate the broken formatting resulting from these inlinings.
	Ellipsis()
	Ellipsis(1)
	Ellipsis(1, 2)
	Ellipsis(1, f(), g())
	Ellipsis(h())
	Ellipsis(i()...)
}

func f() int
func g() int
func h() (int, int)
func i() []any

-- @ellipsis/ellipsis/ellipsis.go --
package ellipsis

func Ellipsis() { //@codeaction("any", "refactor.rewrite.removeUnusedParam", result=ellipsis)
}

func _() {
	// TODO(rfindley): investigate the broken formatting resulting from these inlinings.
	Ellipsis()
	Ellipsis()
	Ellipsis()
	Ellipsis()
	func(_ ...any) {
		Ellipsis()
	}(h())
	Ellipsis()
}

func f() int
func g() int
func h() (int, int)
func i() []any
-- ellipsis2/ellipsis2.go --
package ellipsis2

func Ellipsis2(_, _ int, rest ...int) { //@codeaction("_", "refactor.rewrite.removeUnusedParam", result=ellipsis2)
}

func _() {
	Ellipsis2(1,2,3)
	Ellipsis2(h())
	Ellipsis2(1,2, []int{3, 4}...)
}

func h() (int, int)

-- @ellipsis2/ellipsis2/ellipsis2.go --
package ellipsis2

func Ellipsis2(_ int, rest ...int) { //@codeaction("_", "refactor.rewrite.removeUnusedParam", result=ellipsis2)
}

func _() {
	Ellipsis2(2, 3)
	func(_, blank0 int, rest ...int) {
		Ellipsis2(blank0, rest...)
	}(h())
	Ellipsis2(2, []int{3, 4}...)
}

func h() (int, int)
-- overlapping/overlapping.go --
package overlapping

func Overlapping(i int) int { //@codeaction(re"(i) int", "refactor.rewrite.removeUnusedParam", err=re"overlapping")
	return 0
}

func _() {
	x := Overlapping(Overlapping(0))
	_ = x
}

-- effects/effects.go --
package effects

func effects(x, y int) int { //@ diag("y", re"unused"), codeaction("y", "refactor.rewrite.removeUnusedParam", result=effects)
	return x
}

func f() int
func g() int

func _() {
	effects(f(), g())
	effects(f(), g())
}
-- @effects/effects/effects.go --
package effects

func effects(x int) int { //@ diag("y", re"unused"), codeaction("y", "refactor.rewrite.removeUnusedParam", result=effects)
	return x
}

func f() int
func g() int

func _() {
	effects(f())
	effects(f())
}
-- recursive/recursive.go --
package recursive

func Recursive(x int) int { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=recursive)
	return Recursive(1)
}

-- @recursive/recursive/recursive.go --
package recursive

func Recursive() int { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=recursive)
	return Recursive()
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_formatting.txt
================================================
This test exercises behavior of change signature refactoring with respect to
comments.

Currently, inline comments around arguments or parameters are dropped, which is
probably acceptable. Fixing this is likely intractible without fixing comment
representation in the AST.

-- go.mod --
module unused.mod

go 1.18

-- a/a.go --
package a

// A doc comment.
func A(x /* used parameter */, unused int /* unused parameter */ ) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	// about to return
	return x // returning
	// just returned
}

// This function makes calls.
func _() {
	// about to call
	A(one() /* used arg */, 2 /* unused arg */) // calling
	// just called
}

func one() int {
	// I should be unaffected!
	return 1
}

-- @a/a/a.go --
package a

// A doc comment.
func A(x int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	// about to return
	return x // returning
	// just returned
}

// This function makes calls.
func _() {
	// about to call
	A(one()) // calling
	// just called
}

func one() int {
	// I should be unaffected!
	return 1
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_funcvalue.txt
================================================
This test exercises change signature refactoring handling of function values.

TODO(rfindley): use a literalization strategy to allow these references.

-- go.mod --
module unused.mod

go 1.18

-- a/a.go --
package a

func A(x, unused int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", err=re"non-call function reference")
	return x
}

func _() {
	_ = A
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_imports.txt
================================================
This test checks the behavior of removing a parameter with respect to various
import scenarios.

Wholly unused imports are expected to be removed by a subsequent
"organize imports" step.

-- go.mod --
module mod.test

go 1.21


-- a/a1.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan, <-b.Chan)
}

-- a/a2.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan, <-b.Chan)
	b.B(<-b.Chan, <-b.Chan)
}

-- a/a3.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan, <-b.Chan)
}

func _() {
	b.B(<-b.Chan, <-b.Chan)
}

-- a/a4.go --
package a

// TODO(rfindley/adonovan): inlining here adds an additional import of
// mod.test/b. Can we do better?
import (
	. "mod.test/b"
)

func _() {
	B(<-Chan, <-Chan)
}

-- b/b.go --
package b

import "mod.test/c"

var Chan chan c.C

func B(x, y c.C) { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=b)
}

-- @b/a/a3.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan)
}

func _() {
	b.B(<-b.Chan)
}
-- @b/a/a2.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan)
	b.B(<-b.Chan)
}
-- @b/a/a1.go --
package a

import "mod.test/b"

func _() {
	b.B(<-b.Chan)
}
-- @b/a/a4.go --
package a

// TODO(rfindley/adonovan): inlining here adds an additional import of
// mod.test/b. Can we do better?
import (
	"mod.test/b"
	. "mod.test/b"
)

func _() {
	b.B(<-Chan)
}
-- @b/b/b.go --
package b

import "mod.test/c"

var Chan chan c.C

func B(y c.C) { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=b)
}
-- c/c.go --
package c

type C int

-- d/d.go --
package d

// Removing the parameter should remove this import.
import "mod.test/c"

func D(x c.C) { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=d)
}

func _() {
	D(1)
}

-- @d/d/d.go --
package d

// Removing the parameter should remove this import.

func D() { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=d)
}

func _() {
	D()
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_issue65217.txt
================================================
This test reproduces condition of golang/go#65217, where the inliner created an
unnecessary eta abstraction.

-- go.mod --
module unused.mod

go 1.18

-- a/a.go --
package a

type S struct{}

func (S) Int() int { return 0 }

func _() {
	var s S
	_ = f(s, s.Int())
	var j int
	j = f(s, s.Int())
	_ = j
}

func _() {
	var s S
	i := f(s, s.Int())
	_ = i
}

func f(unused S, i int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=rewrite), diag("unused", re`unused`)
	return i
}

-- @rewrite/a/a.go --
package a

type S struct{}

func (S) Int() int { return 0 }

func _() {
	var s S
	_ = f(s.Int())
	var j int
	j = f(s.Int())
	_ = j
}

func _() {
	var s S
	i := f(s.Int())
	_ = i
}

func f(i int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=rewrite), diag("unused", re`unused`)
	return i
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_method.txt
================================================
This test verifies that gopls can remove unused parameters from methods.

Specifically, check
1. basic removal of unused parameters, when the receiver is named, locally and
   across package boundaries
2. handling of unnamed receivers
3. no panics related to references through interface satisfaction

-- go.mod --
module example.com/rm

go 1.20

-- basic.go --
package rm

type Basic int

func (t Basic) Foo(x int) { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=basic)
}

func _(b Basic) {
	b.Foo(1)
	// TODO(rfindley): methodexprs should not get rewritten as methods.
	Basic.Foo(1, 2)
}

-- basicuse/p.go --
package basicuse

import "example.com/rm"

func _() {
	x := new(rm.Basic)
	x.Foo(sideEffects())
	rm.Basic.Foo(1,2)
}

func sideEffects() int

type Fooer interface {
	Foo(int)
}

// Dynamic calls aren't rewritten.
// Previously, this would cause a bug report or crash (golang/go#69896).
func _(f Fooer) {
	f.Foo(1)
}

-- @basic/basic.go --
package rm

type Basic int

func (t Basic) Foo() { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=basic)
}

func _(b Basic) {
	b.Foo()
	// TODO(rfindley): methodexprs should not get rewritten as methods.
	Basic(1).Foo()
}
-- @basic/basicuse/p.go --
package basicuse

import "example.com/rm"

func _() {
	x := new(rm.Basic)
	x.Foo()
	rm.Basic(1).Foo()
}

func sideEffects() int

type Fooer interface {
	Foo(int)
}

// Dynamic calls aren't rewritten.
// Previously, this would cause a bug report or crash (golang/go#69896).
func _(f Fooer) {
	f.Foo(1)
}
-- missingrecv.go --
package rm

type Missing struct{}

var R2 int

func (Missing) M(a, b, c, r0 int) (r1 int) { //@codeaction("b", "refactor.rewrite.removeUnusedParam", result=missingrecv)
	return a + c
}

func _() {
	m := &Missing{}
	_ = m.M(1, 2, 3, 4)
}

-- missingrecvuse/p.go --
package missingrecvuse

import "example.com/rm"

func _() {
	x := rm.Missing{}
	x.M(1, sideEffects(), 3, 4)
}

func sideEffects() int

-- @missingrecv/missingrecv.go --
package rm

type Missing struct{}

var R2 int

func (Missing) M(a, c, r0 int) (r1 int) { //@codeaction("b", "refactor.rewrite.removeUnusedParam", result=missingrecv)
	return a + c
}

func _() {
	m := &Missing{}
	_ = m.M(1, 3, 4)
}
-- @missingrecv/missingrecvuse/p.go --
package missingrecvuse

import "example.com/rm"

func _() {
	x := rm.Missing{}
	x.M(1, 3, 4)
}

func sideEffects() int


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_resolve.txt
================================================
This test exercises the refactoring to remove unused parameters, with resolve support.
See removeparam.txt for same test without resolve support.

-- go.mod --
module unused.mod

go 1.18

-- a/a.go --
package a

func A(x, unused int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- @a/a/a.go --
package a

func A(x int) int { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", result=a)
	return x
}

-- a/a2.go --
package a

func _() {
	A(1, 2)
}

-- a/a_test.go --
package a

func _() {
	A(1, 2)
}

-- a/a_x_test.go --
package a_test

import "unused.mod/a"

func _() {
	a.A(1, 2)
}

-- b/b.go --
package b

import "unused.mod/a"

func f() int {
	return 1
}

func g() int {
	return 2
}

func _() {
	a.A(f(), 1)
}

var _ = g

-- @a/a/a2.go --
package a

func _() {
	A(1)
}
-- @a/a/a_test.go --
package a

func _() {
	A(1)
}
-- @a/a/a_x_test.go --
package a_test

import "unused.mod/a"

func _() {
	a.A(1)
}
-- @a/b/b.go --
package b

import "unused.mod/a"

func f() int {
	return 1
}

func g() int {
	return 2
}

func _() {
	a.A(f())
}

var _ = g
-- field/field.go --
package field

func Field(x int, field int) { //@codeaction("int", "refactor.rewrite.removeUnusedParam", result=field)
}

func _() {
	Field(1, 2)
}
-- @field/field/field.go --
package field

func Field(field int) { //@codeaction("int", "refactor.rewrite.removeUnusedParam", result=field)
}

func _() {
	Field(2)
}
-- ellipsis/ellipsis.go --
package ellipsis

func Ellipsis(...any) { //@codeaction("any", "refactor.rewrite.removeUnusedParam", result=ellipsis)
}

func _() {
	// TODO(rfindley): investigate the broken formatting resulting from these inlinings.
	Ellipsis()
	Ellipsis(1)
	Ellipsis(1, 2)
	Ellipsis(1, f(), g())
	Ellipsis(h())
	Ellipsis(i()...)
}

func f() int
func g() int
func h() (int, int)
func i() []any

-- @ellipsis/ellipsis/ellipsis.go --
package ellipsis

func Ellipsis() { //@codeaction("any", "refactor.rewrite.removeUnusedParam", result=ellipsis)
}

func _() {
	// TODO(rfindley): investigate the broken formatting resulting from these inlinings.
	Ellipsis()
	Ellipsis()
	Ellipsis()
	Ellipsis()
	func(_ ...any) {
		Ellipsis()
	}(h())
	Ellipsis()
}

func f() int
func g() int
func h() (int, int)
func i() []any
-- ellipsis2/ellipsis2.go --
package ellipsis2

func Ellipsis2(_, _ int, rest ...int) { //@codeaction("_", "refactor.rewrite.removeUnusedParam", result=ellipsis2)
}

func _() {
	Ellipsis2(1,2,3)
	Ellipsis2(h())
	Ellipsis2(1,2, []int{3, 4}...)
}

func h() (int, int)

-- @ellipsis2/ellipsis2/ellipsis2.go --
package ellipsis2

func Ellipsis2(_ int, rest ...int) { //@codeaction("_", "refactor.rewrite.removeUnusedParam", result=ellipsis2)
}

func _() {
	Ellipsis2(2, 3)
	func(_, blank0 int, rest ...int) {
		Ellipsis2(blank0, rest...)
	}(h())
	Ellipsis2(2, []int{3, 4}...)
}

func h() (int, int)
-- overlapping/overlapping.go --
package overlapping

func Overlapping(i int) int { //@codeaction(re"(i) int", "refactor.rewrite.removeUnusedParam", err=re"overlapping")
	return 0
}

func _() {
	x := Overlapping(Overlapping(0))
	_ = x
}

-- effects/effects.go --
package effects

func effects(x, y int) int { //@codeaction("y", "refactor.rewrite.removeUnusedParam", result=effects), diag("y", re"unused")
	return x
}

func f() int
func g() int

func _() {
	effects(f(), g())
	effects(f(), g())
}
-- @effects/effects/effects.go --
package effects

func effects(x int) int { //@codeaction("y", "refactor.rewrite.removeUnusedParam", result=effects), diag("y", re"unused")
	return x
}

func f() int
func g() int

func _() {
	effects(f())
	effects(f())
}
-- recursive/recursive.go --
package recursive

func Recursive(x int) int { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=recursive)
	return Recursive(1)
}

-- @recursive/recursive/recursive.go --
package recursive

func Recursive() int { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=recursive)
	return Recursive()
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_satisfies.txt
================================================
This test verifies that gopls can remove unused parameters from methods,
when that method satisfies an interface.

For now, we just update static calls. In the future, we should compute the set
of dynamic calls that must change (and therefore, the set of concrete functions
that must be modified), in order to produce the desired outcome for our users.

Doing so would be more complicated, so for now this test simply records the
current behavior.

-- go.mod --
module example.com/rm

go 1.20

-- p.go --
package rm

type T int

func (t T) Foo(x int) { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=basic)
}

-- @basic/p.go --
package rm

type T int

func (t T) Foo() { //@codeaction("x", "refactor.rewrite.removeUnusedParam", result=basic)
}

-- @basic/use/use.go --
package use

import "example.com/rm"

type Fooer interface {
	Foo(int)
}

var _ Fooer = rm.T(0)

func _() {
	var x rm.T
	x.Foo()
}
-- use/use.go --
package use

import "example.com/rm"

type Fooer interface{
	Foo(int)
}

var _ Fooer = rm.T(0)

func _() {
	var x rm.T
	x.Foo(1)
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/removeparam_witherrs.txt
================================================
This test checks that we can't remove parameters for packages with errors.

-- p.go --
package p

func foo(unused int) { //@codeaction("unused", "refactor.rewrite.removeUnusedParam", err=re"found 0")
}

func _() {
	foo("") //@diag(`""`, re"cannot use")
}


================================================
FILE: gopls/internal/test/marker/testdata/codeaction/splitlines-variadic.txt
================================================
This is a regression test for #70519, in which the ellipsis
of a variadic call would go missing after split/join lines.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

var a, b, c []any
func f(any, any, ...any)

func _() {
	f(a, b, c...) //@codeaction("a", "refactor.rewrite.splitLines", result=split)

	f(
		a,
		b,
		c..., /*@codeaction("c", "refactor.rewrite.joinLines", result=joined)*/
	)
}

-- @split/a/a.go --
package a

var a, b, c []any
func f(any, any, ...any)

func _() {
	f(
		a,
		b,
		c...,
	) //@codeaction("a", "refactor.rewrite.splitLines", result=split)

	f(
		a,
		b,
		c..., /*@codeaction("c", "refactor.rewrite.joinLines", result=joined)*/
	)
}

-- @joined/a/a.go --
package a

var a, b, c []any
func f(any, any, ...any)

func _() {
	f(a, b, c...) //@codeaction("a", "refactor.rewrite.splitLines", result=split)

	f(a, b, c..., /*@codeaction("c", "refactor.rewrite.joinLines", result=joined)*/)
}



================================================
FILE: gopls/internal/test/marker/testdata/codeaction/splitlines.txt
================================================
This test exercises the refactoring of putting arguments, results, and composite literal elements
into separate lines.

-- go.mod --
module unused.mod

go 1.18

-- func_arg/func_arg.go --
package func_arg

func A(a string, b, c int64, x int, y int) (r1 string, r2, r3 int64, r4 int, r5 int) { //@codeaction("x", "refactor.rewrite.splitLines", result=func_arg)
	return a, b, c, x, y
}

-- @func_arg/func_arg/func_arg.go --
package func_arg

func A(
	a string,
	b, c int64,
	x int,
	y int,
) (r1 string, r2, r3 int64, r4 int, r5 int) { //@codeaction("x", "refactor.rewrite.splitLines", result=func_arg)
	return a, b, c, x, y
}

-- func_ret/func_ret.go --
package func_ret

func A(a string, b, c int64, x int, y int) (r1 string, r2, r3 int64, r4 int, r5 int) { //@codeaction("r1", "refactor.rewrite.splitLines", result=func_ret)
	return a, b, c, x, y
}

-- @func_ret/func_ret/func_ret.go --
package func_ret

func A(a string, b, c int64, x int, y int) (
	r1 string,
	r2, r3 int64,
	r4 int,
	r5 int,
) { //@codeaction("r1", "refactor.rewrite.splitLines", result=func_ret)
	return a, b, c, x, y
}

-- functype_arg/functype_arg.go --
package functype_arg

type A func(a string, b, c int64, x int, y int) (r1 string, r2, r3 int64, r4 int, r5 int) //@codeaction("x", "refactor.rewrite.splitLines", result=functype_arg)

-- @functype_arg/functype_arg/functype_arg.go --
package functype_arg

type A func(
	a string,
	b, c int64,
	x int,
	y int,
) (r1 string, r2, r3 int64, r4 int, r5 int) //@codeaction("x", "refactor.rewrite.splitLines", result=functype_arg)

-- functype_ret/functype_ret.go --
package functype_ret

type A func(a string, b, c int64, x int, y int) (r1 string, r2, r3 int64, r4 int, r5 int) //@codeaction("r1", "refactor.rewrite.splitLines", result=functype_ret)

-- @functype_ret/functype_ret/functype_ret.go --
package functype_ret

type A func(a string, b, c int64, x int, y int) (
	r1 string,
	r2, r3 int64,
	r4 int,
	r5 int,
) //@codeaction("r1", "refactor.rewrite.splitLines", result=functype_ret)

-- func_call/func_call.go --
package func_call

import "fmt"

func F() {
	fmt.Println(1, 2, 3, fmt.Sprintf("hello %d", 4)) //@codeaction("1", "refactor.rewrite.splitLines", result=func_call)
}

-- @func_call/func_call/func_call.go --
package func_call

import "fmt"

func F() {
	fmt.Println(
		1,
		2,
		3,
		fmt.Sprintf("hello %d", 4),
	) //@codeaction("1", "refactor.rewrite.splitLines", result=func_call)
}

-- indent/indent.go --
package indent

import "fmt"

func F() {
	fmt.Println(1, 2, 3, fmt.Sprintf("hello %d", 4)) //@codeaction("hello", "refactor.rewrite.splitLines", result=indent)
}

-- @indent/indent/indent.go --
package indent

import "fmt"

func F() {
	fmt.Println(1, 2, 3, fmt.Sprintf(
		"hello %d",
		4,
	)) //@codeaction("hello", "refactor.rewrite.splitLines", result=indent)
}

-- indent2/indent2.go --
package indent2

import "fmt"

func F() {
	fmt.
		Println(1, 2, 3, fmt.Sprintf("hello %d", 4)) //@codeaction("1", "refactor.rewrite.splitLines", result=indent2)
}

-- @indent2/indent2/indent2.go --
package indent2

import "fmt"

func F() {
	fmt.
		Println(
			1,
			2,
			3,
			fmt.Sprintf("hello %d", 4),
		) //@codeaction("1", "refactor.rewrite.splitLines", result=indent2)
}

-- structelts/structelts.go --
package structelts

type A struct{
	a int
	b int
}

func F() {
	_ = A{a: 1, b: 2} //@codeaction("b", "refactor.rewrite.splitLines", result=structelts)
}

-- @structelts/structelts/structelts.go --
package structelts

type A struct{
	a int
	b int
}

func F() {
	_ = A{
		a: 1,
		b: 2,
	} //@codeaction("b", "refactor.rewrite.splitLines", result=structelts)
}

-- sliceelts/sliceelts.go --
package sliceelts

func F() {
	_ = []int{1, 2} //@codeaction("1", "refactor.rewrite.splitLines", result=sliceelts)
}

-- @sliceelts/sliceelts/sliceelts.go --
package sliceelts

func F() {
	_ = []int{
		1,
		2,
	} //@codeaction("1", "refactor.rewrite.splitLines", result=sliceelts)
}

-- mapelts/mapelts.go --
package mapelts

func F() {
	_ = map[string]int{"a": 1, "b": 2} //@codeaction("1", "refactor.rewrite.splitLines", result=mapelts)
}

-- @mapelts/mapelts/mapelts.go --
package mapelts

func F() {
	_ = map[string]int{
		"a": 1,
		"b": 2,
	} //@codeaction("1", "refactor.rewrite.splitLines", result=mapelts)
}

-- starcomment/starcomment.go --
package starcomment

func A(/*1*/ x /*2*/ string /*3*/, /*4*/ y /*5*/ int /*6*/) (string, int) { //@codeaction("x", "refactor.rewrite.splitLines", result=starcomment)
	return x, y
}

-- @starcomment/starcomment/starcomment.go --
package starcomment

func A(
	/*1*/ x /*2*/ string /*3*/,
	/*4*/ y /*5*/ int /*6*/,
) (string, int) { //@codeaction("x", "refactor.rewrite.splitLines", result=starcomment)
	return x, y
}



================================================
FILE: gopls/internal/test/marker/testdata/codelens/generate.txt
================================================
This test exercises the "generate" codelens.

-- generate.go --
//@codelenses()

package generate

//go:generate echo Hi //@ codelens("//go:generate", "run go generate"), codelens("//go:generate", "run go generate ./...")
//go:generate echo I shall have no CodeLens


================================================
FILE: gopls/internal/test/marker/testdata/codelens/test.txt
================================================
This file tests codelenses for test functions.

TODO: for some reason these code lens have zero width. Does that affect their
utility/visibility in various LSP clients?

-- settings.json --
{
	"codelenses": {
		"test": true
	}
}

-- p_test.go --
//@codelenses()

package codelens //@codelens(re"()package codelens", "run file benchmarks")

import "testing"

func TestMain(m *testing.M) {} // no code lens for TestMain

func TestFuncWithCodeLens(t *testing.T) { //@codelens(re"()func", "run test")
}

func thisShouldNotHaveACodeLens(t *testing.T) { //@diag("t ", re"unused parameter")
	println() // nonempty body => "unused parameter"
}

func BenchmarkFuncWithCodeLens(b *testing.B) { //@codelens(re"()func", "run benchmark")
}

func helper() {} // expect no code lens

func _() {
	// pacify unusedfunc
	thisShouldNotHaveACodeLens(nil)
	helper()
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/address.txt
================================================
This test exercises the reference and dereference completion modifiers.

TODO: remove the need to set "literalCompletions" here, as this is one of the
few places this setting is needed.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- address/address.go --
package address

func wantsPtr(*int)            {}
func wantsVariadicPtr(...*int) {}

func wantsVariadic(...int) {}

type foo struct{ c int } //@item(addrFieldC, "c", "int", "field")

func _() {
	var (
		a string //@item(addrA, "a", "string", "var")
		b int    //@item(addrB, "b", "int", "var")
	)

	wantsPtr()   //@rank(re"()\\)", addrB, addrA),snippet(re"()\\)", addrB, "&b")
	wantsPtr(&b) //@snippet(re"()\\)", addrB, "b")

	wantsVariadicPtr() //@rank(re"()\\)", addrB, addrA),snippet(re"()\\)", addrB, "&b")

	var s foo
	s.c          //@item(addrDeepC, "s.c", "int", "field")
	wantsPtr()   //@snippet(re"()\\)", addrDeepC, "&s.c")
	wantsPtr(s)  //@snippet(re"()\\)", addrDeepC, "&s.c")
	wantsPtr(&s) //@snippet(re"()\\)", addrDeepC, "s.c")

	// don't add "&" in item (it gets added as an additional edit)
	wantsPtr(&s.c) //@snippet(re"()\\)", addrFieldC, "c")

	// check dereferencing as well
	var c *int    //@item(addrCPtr, "c", "*int", "var")
	var _ int = _ //@rank(re"= ()", addrCPtr, addrA),snippet(re"= ()", addrCPtr, "*c")

	wantsVariadic() //@rank(re"()\\)", addrCPtr, addrA),snippet(re"()\\)", addrCPtr, "*c")

	var d **int   //@item(addrDPtr, "d", "**int", "var")
	var _ int = _ //@rank(re"= ()", addrDPtr, addrA),snippet(re"= ()", addrDPtr, "**d")

	type namedPtr *int
	var np namedPtr //@item(addrNamedPtr, "np", "namedPtr", "var")

	var _ int = _ //@rank(re"= ()", addrNamedPtr, addrA)

	// don't get tripped up by recursive pointer type
	type dontMessUp *dontMessUp //@item(dontMessUp, "dontMessUp", "*dontMessUp", "type")
	var dmu *dontMessUp //@item(addrDMU, "dmu", "*dontMessUp", "var")

	var _ int = dmu //@complete(re"dmu()", addrDMU, dontMessUp)
}

func (f foo) ptr() *foo { return &f }

func _() {
	getFoo := func() foo { return foo{} }

	// not addressable
	getFoo().c //@item(addrGetFooC, "getFoo().c", "int", "field")

	// addressable
	getFoo().ptr().c //@item(addrGetFooPtrC, "getFoo().ptr().c", "int", "field")

	wantsPtr()   //@snippet(re"()\\)", addrGetFooPtrC, "&getFoo().ptr().c")
	wantsPtr(&g) //@snippet(re"()\\)", addrGetFooPtrC, "getFoo().ptr().c")
}

type nested struct {
	f foo
}

func _() {
	getNested := func() nested { return nested{} }

	getNested().f.c       //@item(addrNestedC, "getNested().f.c", "int", "field")
	getNested().f.ptr().c //@item(addrNestedPtrC, "getNested().f.ptr().c", "int", "field")

	// addrNestedC is not addressable, so rank lower
	wantsPtr(getNestedfc) //@complete(re"()\\)", addrNestedPtrC, addrNestedC)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/alias.txt
================================================
This test checks completion related to aliases.

-- flags --
-ignore_extra_diags

-- aliases.go --
package aliases

// Copied from the old builtins.go, which has been ported to the new marker tests.
/* string */ //@item(string, "string", "", "type")
/* int */ //@item(int, "int", "", "type")
/* float32 */ //@item(float32, "float32", "", "type")
/* float64 */ //@item(float64, "float64", "", "type")

type p struct{}

type s[a int | string] = p

func _() {
	s[]{} //@rank(re"()]", int, float64)
}

func takesGeneric[a int | string](s[a]) {
	"s[a]{}" //@item(tpInScopeLit, "s[a]{}", "", "var")
	takesGeneric() //@rank(re"()\\)", tpInScopeLit),snippet(re"()\\)", tpInScopeLit, "s[a]{\\}")
}

func _() {
	s[int]{} //@item(tpInstLit, "s[int]{}", "", "var")
	takesGeneric[int]() //@rank(re"()\\)", tpInstLit),snippet(re"()\\)", tpInstLit, "s[int]{\\}")

	"s[...]{}" //@item(tpUninstLit, "s[...]{}", "", "var")
	takesGeneric() //@rank(re"()\\)", tpUninstLit),snippet(re"()\\)", tpUninstLit, "s[${1:}]{\\}")
}


type myType int //@item(flType, "myType", "int", "type")

type myt[T int] myType //@item(aflType, "myt[T]", "int", "type")

func (my myt) _() {} //@complete(re"()\\) _", flType, aflType)


================================================
FILE: gopls/internal/test/marker/testdata/completion/anon.txt
================================================
This test checks completion related to anonymous structs.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"deepCompletion": false
}

-- anon.go --
package anon

// Literal completion results.
/* int() */ //@item(int, "int()", "int", "var")

func _() {
	for _, _ := range []struct {
		i, j int //@item(anonI, "i", "int", "field"),item(anonJ, "j", "int", "field")
	}{
		{
			i: 1,
			//@complete("", anonJ)
		},
		{
			//@complete("", anonI, anonJ, int)
		},
	} {
		continue
	}

	s := struct{ f int }{  } //@item(anonF, "f", "int", "field"),item(structS, "s", "struct{...}", "var"),complete(re"()  }", anonF, int)

	_ = map[struct{ x int }]int{ //@item(anonX, "x", "int", "field")
		struct{ x int }{  }: 1, //@complete(re"()  }", anonX, int, structS)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/append.txt
================================================
This test checks behavior of completion within append expressions.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/append

go 1.18

-- append.go --
package append

func foo([]string)  {}
func bar(...string) {}

func _() {
	var (
		aInt     []int    //@item(appendInt, "aInt", "[]int", "var")
		aStrings []string //@item(appendStrings, "aStrings", "[]string", "var")
		aString  string   //@item(appendString, "aString", "string", "var")
	)

	append(aStrings, a)                     //@rank(re"()\\)", appendString, appendInt)
	var _ any = append(aStrings, a) //@rank(re"()\\)", appendString, appendInt)
	var _ []string = append(oops, a)        //@rank(re"()\\)", appendString, appendInt)

	foo(append())                  //@rank(re"()\\)\\)", appendStrings, appendInt),rank(re"()\\)\\)", appendStrings, appendString)
	foo(append([]string{}, a))     //@rank(re"()\\)\\)", appendStrings, appendInt),rank(re"()\\)\\)", appendString, appendInt),snippet(re"()\\)\\)", appendStrings, "aStrings...")
	foo(append([]string{}, "", a)) //@rank(re"()\\)\\)", appendString, appendInt),rank(re"()\\)\\)", appendString, appendStrings)

	// Don't add "..." to append() argument.
	bar(append()) //@snippet(re"()\\)\\)", appendStrings, "aStrings")

	type baz struct{}
	baz{}                       //@item(appendBazLiteral, "baz{}", "", "var")
	var bazzes []baz            //@item(appendBazzes, "bazzes", "[]baz", "var")
	var bazzy baz               //@item(appendBazzy, "bazzy", "baz", "var")
	bazzes = append(bazzes, ba) //@rank(re"()\\)", appendBazzy, appendBazLiteral, appendBazzes)

	var b struct{ b []baz }
	b.b                  //@item(appendNestedBaz, "b.b", "[]baz", "field")
	b.b = append(b.b, b) //@rank(re"()\\)", appendBazzy, appendBazLiteral, appendNestedBaz)

	var aStringsPtr *[]string  //@item(appendStringsPtr, "aStringsPtr", "*[]string", "var")
	foo(append([]string{}, a)) //@snippet(re"()\\)\\)", appendStringsPtr, "*aStringsPtr...")

	foo(append([]string{}, *a)) //@snippet(re"()\\)\\)", appendStringsPtr, "aStringsPtr...")
}

-- append2.go --
package append

func _() {
	_ = append(a, struct) //@complete(re"()\\)", structs)
}

//@item(structs, "structs", `"structs"`)


================================================
FILE: gopls/internal/test/marker/testdata/completion/assign.txt
================================================
This test checks that completion considers assignability when ranking results.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/assign

go 1.18

-- settings.json --
{
	"completeUnimported": false
}

-- assign.go --
package assign

import "golang.org/lsptests/assign/internal/secret"

func _() {
	secret.Hello()
	var (
		myInt int //@item(assignInt, "myInt", "int", "var")
		myStr string //@item(assignStr, "myStr", "string", "var")
	)

	var _ string = my //@rank(re"() \\/\\/", assignStr, assignInt)
	var _ string = //@rank(re"() \\/\\/", assignStr, assignInt)
}

func _() {
	var a string = a //@complete(re"() \\/\\/")
}

func _() {
	fooBar := fooBa //@complete(re"() \\/\\/"),item(assignFooBar, "fooBar", "", "var")
	abc, fooBar := 123, fooBa //@complete(re"() \\/\\/", assignFooBar)
	{
		fooBar := fooBa //@complete(re"() \\/\\/", assignFooBar)
	}
}

-- internal/secret/secret.go --
package secret

func Hello() {}


================================================
FILE: gopls/internal/test/marker/testdata/completion/bad.txt
================================================
This test exercises completion in the presence of type errors.

Note: this test was ported from the old marker tests, which did not enable
unimported completion. Enabling it causes matches in e.g. crypto/rand.

-- settings.json --
{
	"completeUnimported": false
}

-- go.mod --
module bad.test

go 1.18

-- bad/bad0.go --
package bad

func stuff() { //@item(stuff, "stuff", "func()", "func")
	x := "heeeeyyyy"
	random2(x) //@diag("x", re"cannot use x \\(variable of type string\\) as int value in argument to random2")
	random2(1) //@complete(re"()dom", random, random2, random3)
	y := 3     //@diag("y", re"declared (and|but) not used")
}

type bob struct { //@item(bob, "bob", "struct{...}", "struct")
	x int
}

func _() {
	var q int
	_ = &bob{
		f: q, //@diag("f: q", re"unknown field f in struct literal")
	}
}

-- bad/bad1.go --
package bad

// See #36637
type stateFunc func() stateFunc //@item(stateFunc, "stateFunc", "func() stateFunc", "type")

var a unknown //@item(global_a, "a", "unknown", "var"),diag("unknown", re"(undeclared name|undefined): unknown")

func random() int { //@item(random, "random", "func() int", "func")
	//@complete("", global_a, bob, random, random2, random3, stateFunc, stuff)
	return 0
}

func random2(y int) int { //@item(random2, "random2", "func(y int) int", "func"),item(bad_y_param, "y", "int", "var")
	x := 6       //@item(x, "x", "int", "var"),diag("x", re"declared (and|but) not used")
	var q blah   //@item(q, "q", "blah", "var"),diag("q", re"declared (and|but) not used"),diag("blah", re"(undeclared name|undefined): blah")
	var t **blob //@item(t, "t", "**blob", "var"),diag("t", re"declared (and|but) not used"),diag("blob", re"(undeclared name|undefined): blob")
	//@complete("", q, t, x, bad_y_param, global_a, bob, random, random2, random3, stateFunc, stuff)

	return y
}

func random3(y ...int) { //@item(random3, "random3", "func(y ...int)", "func"),item(y_variadic_param, "y", "[]int", "var")
	//@complete("", y_variadic_param, global_a, bob, random, random2, random3, stateFunc, stuff)

	var ch chan (favType1)   //@item(ch, "ch", "chan (favType1)", "var"),diag("ch", re"declared (and|but) not used"),diag("favType1", re"(undeclared name|undefined): favType1")
	var m map[keyType]int    //@item(m, "m", "map[keyType]int", "var"),diag("m", re"declared (and|but) not used"),diag("keyType", re"(undeclared name|undefined): keyType")
	var arr []favType2       //@item(arr, "arr", "[]favType2", "var"),diag("arr", re"declared (and|but) not used"),diag("favType2", re"(undeclared name|undefined): favType2")
	var fn1 func() badResult //@item(fn1, "fn1", "func() badResult", "var"),diag("fn1", re"declared (and|but) not used"),diag("badResult", re"(undeclared name|undefined): badResult")
	var fn2 func(badParam)   //@item(fn2, "fn2", "func(badParam)", "var"),diag("fn2", re"declared (and|but) not used"),diag("badParam", re"(undeclared name|undefined): badParam")
	//@complete("", arr, ch, fn1, fn2, m, y_variadic_param, global_a, bob, random, random2, random3, stateFunc, stuff)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/basic_lit.txt
================================================
This test checks completion related to basic literals.

-- flags --
-ignore_extra_diags

-- basiclit.go --
package basiclit

func _() {
	var a int // something for lexical completions

	_ = "hello." //@complete(re"()\\.")

	_ = 1 //@complete(re"() \\/\\/")

	_ = 1. //@complete(re"()\\.")

	_ = 'a' //@complete(re"()\\' ")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/builtins.txt
================================================
This test checks completion of Go builtins.

-- flags --
-ignore_extra_diags
-filter_builtins=false

-- builtin_args.go --
package builtins

func _() {
	var (
		aSlice    []int          //@item(builtinSlice, "aSlice", "[]int", "var")
		aMap      map[string]int //@item(builtinMap, "aMap", "map[string]int", "var")
		aString   string         //@item(builtinString, "aString", "string", "var")
		aArray    [0]int         //@item(builtinArray, "aArray", "[0]int", "var")
		aArrayPtr *[0]int        //@item(builtinArrayPtr, "aArrayPtr", "*[0]int", "var")
		aChan     chan int       //@item(builtinChan, "aChan", "chan int", "var")
		aPtr      *int           //@item(builtinPtr, "aPtr", "*int", "var")
		aInt      int            //@item(builtinInt, "aInt", "int", "var")
	)

	type (
		aSliceType []int          //@item(builtinSliceType, "aSliceType", "[]int", "type")
		aChanType  chan int       //@item(builtinChanType, "aChanType", "chan int", "type")
		aMapType   map[string]int //@item(builtinMapType, "aMapType", "map[string]int", "type")
	)

	close() //@rank(re"()\\)", builtinChan, builtinSlice)

	append() //@rank(re"()\\)", builtinSlice, builtinChan)

	var _ []byte = append([]byte(nil), ""...) //@rank(re"()\\) \\/\\/")

	copy()           //@rank(re"()\\)", builtinSlice, builtinChan)
	copy(aSlice, aS) //@rank(re"()\\)", builtinSlice, builtinString)
	copy(aS, aSlice) //@rank(re"(),", builtinSlice, builtinString)

	delete()         //@rank(re"()\\)", builtinMap, builtinChan)
	delete(aMap, aS) //@rank(re"()\\)", builtinString, builtinSlice)

	aMapFunc := func() map[int]int { //@item(builtinMapFunc, "aMapFunc", "func() map[int]int", "var")
		return nil
	}
	delete() //@rank(re"()\\)", builtinMapFunc, builtinSlice)

	len() //@rank(re"()\\)", builtinSlice, builtinInt),rank(re"()\\)", builtinMap, builtinInt),rank(re"()\\)", builtinString, builtinInt),rank(re"()\\)", builtinArray, builtinInt),rank(re"()\\)", builtinArrayPtr, builtinPtr),rank(re"()\\)", builtinChan, builtinInt)

	cap() //@rank(re"()\\)", builtinSlice, builtinMap),rank(re"()\\)", builtinArray, builtinString),rank(re"()\\)", builtinArrayPtr, builtinPtr),rank(re"()\\)", builtinChan, builtinInt)

	make()              //@rank(re"()\\)", builtinMapType, int),rank(re"()\\)", builtinChanType, int),rank(re"()\\)", builtinSliceType, int),rank(re"()\\)", builtinMapType, int)
	make(aSliceType, a) //@rank(re"()\\)", builtinInt, builtinSlice)

	type myInt int
	var mi myInt        //@item(builtinMyInt, "mi", "myInt", "var")
	make(aSliceType, m) //@snippet(re"()\\)", builtinMyInt, "mi")

	var _ []int = make() //@rank(re"()\\)", builtinSliceType, builtinMapType)

	type myStruct struct{}  //@item(builtinStructType, "myStruct", "struct{...}", "struct")
	var _ *myStruct = new() //@rank(re"()\\)", builtinStructType, int)

	for k := range a { //@rank(re"() {", builtinSlice, builtinInt),rank(re"() {", builtinString, builtinInt),rank(re"() {", builtinChan, builtinInt),rank(re"() {", builtinArray, builtinInt),rank(re"() {", builtinArrayPtr, builtinInt),rank(re"() {", builtinMap, builtinInt),
	}

	for k, v := range a { //@rank(re"() {", builtinSlice, builtinChan)
	}

	<-a //@rank(re"() \\/\\/", builtinChan, builtinInt)
}

-- builtin_types.go --
package builtins

func _() {
	var _ []bool //@item(builtinBoolSliceType, "[]bool", "[]bool", "type")

	var _ []bool = make() //@rank(re"()\\)", builtinBoolSliceType, int)

	var _ []bool = make([], 0) //@rank(re"(),", bool, int)

	var _ [][]bool = make([][], 0) //@rank(re"(),", bool, int)
}

-- builtins.go --
package builtins

// Definitions of builtin completion items that are still used in tests.

/* bool */ //@item(bool, "bool", "", "type")
/* complex(r float64, i float64) */ //@item(complex, "complex", "func(r float64, i float64) complex128", "func")
/* float32 */ //@item(float32, "float32", "", "type")
/* float64 */ //@item(float64, "float64", "", "type")
/* imag(c complex128) float64 */ //@item(imag, "imag", "func(c complex128) float64", "func")
/* int */ //@item(int, "int", "", "type")
/* iota */ //@item(iota, "iota", "", "const")
/* string */ //@item(string, "string", "", "type")
/* true */ //@item(_true, "true", "", "const")

-- constants.go --
package builtins

func _() {
	const (
		foo = iota //@complete(re"() \\/\\/", iota)
	)

	iota //@complete(re"() \\/\\/")

	var iota int //@item(iotaVar, "iota", "int", "var")

	iota //@complete(re"() \\/\\/", iotaVar)
}

func _() {
	var twoRedUpEnd bool //@item(TRUEVar, "twoRedUpEnd", "bool", "var")

	var _ bool = true //@rank(re"() \\/\\/", _true, TRUEVar)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/casesensitive.txt
================================================
This test exercises the caseSensitive completion matcher.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false,
	"matcher": "caseSensitive"
}

-- casesensitive.go --
package casesensitive

func _() {
	var lower int //@item(lower, "lower", "int", "var")
	var Upper int //@item(upper, "Upper", "int", "var")

	l //@complete(re"() \\/\\/", lower)
	U //@complete(re"() \\/\\/", upper)

	L //@complete(re"() \\/\\/")
	u //@complete(re"() \\/\\/")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/cast.txt
================================================
This test checks completion related to casts.

-- flags --
-ignore_extra_diags

-- cast.go --
package cast

func _() {
	foo := struct{x int}{x: 1} //@item(x_field, "x", "int", "field")
	_ = float64(foo.x) //@complete(re"()x", x_field)
}

func _() {
	foo := struct{x int}{x: 1}
	_ = float64(foo. //@complete(re"() \\/", x_field)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/channel.txt
================================================
This test checks completion related to channels.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- channel.go --
package channel

func _() {
	var (
		aa = "123" //@item(channelAA, "aa", "string", "var")
		ab = 123   //@item(channelAB, "ab", "int", "var")
	)

	{
		type myChan chan int
		var mc myChan
		mc <- a //@complete(re"() \\/\\/", channelAB, channelAA)
	}

	{
		var ac chan int //@item(channelAC, "ac", "chan int", "var")
		a <- a //@complete(re"() <-", channelAC, channelAA, channelAB)
	}

	{
		var foo chan int //@item(channelFoo, "foo", "chan int", "var")
		wantsInt := func(int) {} //@item(channelWantsInt, "wantsInt", "func(int)", "var")
		wantsInt(<-) //@rank(re"()\\)", channelFoo, channelAB)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/comment.txt
================================================
This test checks behavior of completion within comments.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/comment

go 1.18

-- p.go --
package comment_completion

var p bool

//@complete(re"//()")

func _() {
	var a int

	switch a {
	case 1:
		//@complete(re"//()")
		_ = a
	}

	var b chan int
	select {
	case <-b:
		//@complete(re"//()")
		_ = b
	}

	var (
		//@complete(re"//()")
		_ = a
	)
}

// //@complete(re"() ", variableC)
var C string //@item(variableC, "C", "string", "var") //@complete(re"() ", variableC)

// //@complete(re"() ", constant)
const Constant = "example" //@item(constant, "Constant", "string", "const") //@complete(re"() ", constant)

// //@complete(re"() ", structType, fieldB, fieldA)
type StructType struct { //@item(structType, "StructType", "struct{...}", "struct") //@complete(re"() ", structType, fieldA, fieldB)
	// //@complete(re"() ", fieldA, structType, fieldB)
	A string //@item(fieldA, "A", "string", "field") //@complete(re"() ", fieldA, structType, fieldB)
	b int    //@item(fieldB, "b", "int", "field") //@complete(re"() ", fieldB, structType, fieldA)
}

// //@complete(re"() ", method, structRecv, paramX, resultY, fieldB, fieldA)
func (structType *StructType) Method(X int) (Y int) { //@item(structRecv, "structType", "*StructType", "var"),item(method, "Method", "func(X int) (Y int)", "method"),item(paramX, "X", "int", "var"),item(resultY, "Y", "int", "var")
	// //@complete(re"() ", method, structRecv, paramX, resultY, fieldB, fieldA)
	return
}

// //@complete(re"() ", newType)
type NewType string //@item(newType, "NewType", "string", "type") //@complete(re"() ", newType)

// //@complete(re"() ", testInterface, testA, testB)
type TestInterface interface { //@item(testInterface, "TestInterface", "interface{...}", "interface")
	// //@complete(re"() ", testA, testInterface, testB)
	TestA(L string) (M int) //@item(testA, "TestA", "func(L string) (M int)", "method"),item(paramL, "L", "var", "string"),item(resM, "M", "var", "int") //@complete(re"() ", testA, testInterface, testB)
	TestB(N int) bool       //@item(testB, "TestB", "func(N int) bool", "method"),item(paramN, "N", "var", "int") //@complete(re"() ", testB, testInterface, testA)
}

// //@complete(re"() ", function)
func Function() int { //@item(function, "Function", "func() int", "func") //@complete(re"() ", function)
	// //@complete(re"() ", function)
	return 0
}

// This tests multiline block comments and completion with prefix
// Lorem Ipsum Multili//@complete(re"()Multi", multiline)
// Lorem ipsum dolor sit ametom
func Multiline() int { //@item(multiline, "Multiline", "func() int", "func")
	// //@complete(re"() ", multiline)
	return 0
}

// This test checks that gopls does not panic if the receiver is syntactically
// present but empty.
//
// //@complete(re"() ")
func () _() {}


// This test checks that gopls does not panic if there is a duplicate declaration.
func f() {}

// //@complete(re"() ")
func () f() {}

================================================
FILE: gopls/internal/test/marker/testdata/completion/complit.txt
================================================
This test checks completion related to composite literals.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- complit.go --
package complit

// Literal completion results.
/* int() */ //@item(int, "int()", "int", "var")

// general completions

type position struct { //@item(structPosition, "position", "struct{...}", "struct")
	X, Y int //@item(fieldX, "X", "int", "field"),item(fieldY, "Y", "int", "field")
}

func _() {
	_ = position{
		//@complete("", fieldX, fieldY, int, structPosition)
	}
	_ = position{
		X: 1,
		//@complete("", fieldY)
	}
	_ = position{
		//@complete("", fieldX)
		Y: 1,
	}
	_ = []*position{
        {
            //@complete("", fieldX, fieldY, int, structPosition)
        },
	}
}

func _() {
	var (
		aa string //@item(aaVar, "aa", "string", "var")
		ab int    //@item(abVar, "ab", "int", "var")
	)

	_ = map[int]int{
		a: a, //@complete(re"():", abVar, aaVar),complete(re"(),", abVar, aaVar)
	}

	_ = map[int]int{
		//@complete("", abVar, int, aaVar, structPosition)
	}

	_ = []string{a: ""} //@complete(re"():", abVar, aaVar)
	_ = [1]string{a: ""} //@complete(re"():", abVar, aaVar)

	_ = position{X: a}   //@complete(re"()}", abVar, aaVar)
	_ = position{a}      //@complete(re"()}", abVar, aaVar)
	_ = position{a, }      //@complete(re"()}", abVar, int, aaVar, structPosition)

	_ = []int{a}  //@complete(re"()}", abVar, aaVar)
	_ = [1]int{a} //@complete(re"()}", abVar, aaVar)

	type myStruct struct {
		AA int    //@item(fieldAA, "AA", "int", "field")
		AB string //@item(fieldAB, "AB", "string", "field")
	}

	_ = myStruct{
		AB: a, //@complete(re"(),", aaVar, abVar)
	}

	var s myStruct

	_ = map[int]string{1: "" + s.A}                                //@complete(re"()}", fieldAB, fieldAA)
	_ = map[int]string{1: (func(i int) string { return "" })(s.A)} //@complete(re"()\\)}", fieldAA, fieldAB)
	_ = map[int]string{1: func() string { s.A }}                   //@complete(re"() }", fieldAA, fieldAB)

	_ = position{s.A} //@complete(re"()}", fieldAA, fieldAB)

	var X int //@item(varX, "X", "int", "var")
	_ = position{X}      //@complete(re"()}", fieldX, varX)
}

func _() {
	type foo struct{} //@item(complitFoo, "foo", "struct{...}", "struct")

	var _ *foo = &fo{} //@snippet(re"()\\{", complitFoo, "foo")
	var _ *foo = fo{} //@snippet(re"()\\{", complitFoo, "&foo")

	struct { a, b *foo }{
		a: &fo{}, //@rank(re"(){", complitFoo)
		b: fo{}, //@snippet(re"()\\{", complitFoo, "&foo")
	}
}

func _() {
	_ := position{
		X: 1, //@complete(re"()X", fieldX),complete(re"() 1", int, structPosition)
		Y: ,  //@complete(re"():", fieldY),complete(re"() ,", int, structPosition)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/constant.txt
================================================
This test checks completion related to constants.

-- flags --
-ignore_extra_diags

-- constant.go --
package constant

const x = 1 //@item(constX, "x", "int", "const")

const (
	a int = iota << 2 //@item(constA, "a", "int", "const")
	b                 //@item(constB, "b", "int", "const")
	c                 //@item(constC, "c", "int", "const")
)

func _() {
	const y = "hi" //@item(constY, "y", "string", "const")
	//@complete("", constY, constA, constB, constC, constX)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/danglingstmt.txt
================================================
This test checks that completion works as expected in the presence of
incomplete statements that may affect parser recovery.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/dangling

go 1.18

-- settings.json --
{
	"completeUnimported": false,
	"deepCompletion": false
}

-- dangling_for.go --
package danglingstmt

func _() {
	for bar //@rank(re"() \\/\\/", danglingBar)
}

func bar() bool { //@item(danglingBar, "bar", "func() bool", "func")
	return true
}

-- dangling_for_init.go --
package danglingstmt

func _() {
	for i := bar //@rank(re"() \\/\\/", danglingBar2)
}

func bar2() int { //@item(danglingBar2, "bar2", "func() int", "func")
	return 0
}

-- dangling_for_init_cond.go --
package danglingstmt

func _() {
	for i := bar3(); i > bar //@rank(re"() \\/\\/", danglingBar3)
}

func bar3() int { //@item(danglingBar3, "bar3", "func() int", "func")
	return 0
}

-- dangling_for_init_cond_post.go --
package danglingstmt

func _() {
	for i := bar4(); i > bar4(); i += bar //@rank(re"() \\/\\/", danglingBar4)
}

func bar4() int { //@item(danglingBar4, "bar4", "func() int", "func")
	return 0
}

-- dangling_if.go --
package danglingstmt

func _() {
	if foo //@rank(re"() \\/\\/", danglingFoo)
}

func foo() bool { //@item(danglingFoo, "foo", "func() bool", "func")
	return true
}

-- dangling_if_eof.go --
package danglingstmt

func bar5() bool { //@item(danglingBar5, "bar5", "func() bool", "func")
	return true
}

func _() {
	if b //@rank(re"() \\/\\/", danglingBar5)

-- dangling_if_init.go --
package danglingstmt

func _() {
	if i := foo //@rank(re"() \\/\\/", danglingFoo2)
}

func foo2() bool { //@item(danglingFoo2, "foo2", "func() bool", "func")
	return true
}

-- dangling_if_init_cond.go --
package danglingstmt

func _() {
	if i := 123; foo //@rank(re"() \\/\\/", danglingFoo3)
}

func foo3() bool { //@item(danglingFoo3, "foo3", "func() bool", "func")
	return true
}

-- dangling_multiline_if.go --
package danglingstmt

func walrus() bool { //@item(danglingWalrus, "walrus", "func() bool", "func")
	return true
}

func _() {
	if true &&
		walrus //@complete(re"() \\/\\/", danglingWalrus)
}

-- dangling_selector_1.go --
package danglingstmt

func _() {
	x. //@rank(re"() \\/\\/", danglingI)
}

var x struct { i int } //@item(danglingI, "i", "int", "field")

-- dangling_selector_2.go --
package danglingstmt

// TODO: re-enable this test, which was broken when the foo package was removed.
// (we can replicate the relevant definitions in the new marker test)
// import "golang.org/lsptests/foo"

func _() {
	foo. // rank(re"() \\/\\/", Foo)
	var _ = []string{foo.} // rank(re"()}", Foo)
}

-- dangling_switch_init.go --
package danglingstmt

func _() {
	switch i := baz //@rank(re"() \\/\\/", danglingBaz)
}

func baz() int { //@item(danglingBaz, "baz", "func() int", "func")
	return 0
}

-- dangling_switch_init_tag.go --
package danglingstmt

func _() {
	switch i := 0; baz //@rank(re"() \\/\\/", danglingBaz2)
}

func baz2() int { //@item(danglingBaz2, "baz2", "func() int", "func")
	return 0
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/deep.txt
================================================
This test exercises deep completion.

-- settings.json --
{
	"completeUnimported": false,
	"matcher": "caseInsensitive"
}

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- deep/deep.go --
package deep

import "context"

type deepA struct {
	b deepB //@item(deepBField, "b", "deepB", "field")
}

type deepB struct {
}

func wantsDeepB(deepB) {}

func _() {
	var a deepA   //@item(deepAVar, "a", "deepA", "var")
	a.b           //@item(deepABField, "a.b", "deepB", "field")
	wantsDeepB(a) //@complete(re"()\\)", deepABField, deepAVar)

	deepA{a} //@snippet(re"()}", deepABField, "a.b")
}

func wantsContext(context.Context) {}

func _() {
	context.Background() //@item(ctxBackground, "context.Background", "func() context.Context", "func", "Background returns a non-nil, empty Context.")
	context.TODO()       //@item(ctxTODO, "context.TODO", "func() context.Context", "func", "TODO returns a non-nil, empty Context.")

	wantsContext(c) //@rank(re"()\\)", ctxBackground),rank(re"()\\)", ctxTODO)
}

func _() {
	var cork struct{ err error }
	cork.err         //@item(deepCorkErr, "cork.err", "error", "field")
	context          //@item(deepContextPkg, "context", "\"context\"", "package")
	var _ error = co // rank(re"() \\/\\/", deepCorkErr, deepContextPkg)
}

func _() {
	// deepCircle is circular.
	type deepCircle struct {
		*deepCircle
	}
	var circle deepCircle   //@item(deepCircle, "circle", "deepCircle", "var")
	circle.deepCircle       //@item(deepCircleField, "circle.deepCircle", "*deepCircle", "field")
	var _ deepCircle = circ //@complete(re"() \\/\\/", deepCircle, deepCircleField),snippet(re"() \\/\\/", deepCircleField, "*circle.deepCircle")
}

func _() {
	type deepEmbedC struct {
	}
	type deepEmbedB struct {
		deepEmbedC
	}
	type deepEmbedA struct {
		deepEmbedB
	}

	wantsC := func(deepEmbedC) {}

	var a deepEmbedA //@item(deepEmbedA, "a", "deepEmbedA", "var")
	a.deepEmbedB     //@item(deepEmbedB, "a.deepEmbedB", "deepEmbedB", "field")
	a.deepEmbedC     //@item(deepEmbedC, "a.deepEmbedC", "deepEmbedC", "field")
	wantsC(a)        //@complete(re"()\\)", deepEmbedC, deepEmbedA, deepEmbedB)
}

func _() {
	type nested struct {
		a int
		n *nested //@item(deepNestedField, "n", "*nested", "field")
	}

	nested{
		a: 123, //@complete(re"() \\/\\/", deepNestedField)
	}
}

func _() {
	var a struct {
		b struct {
			c int
		}
		d int
	}

	a.d   //@item(deepAD, "a.d", "int", "field")
	a.b.c //@item(deepABC, "a.b.c", "int", "field")
	a.b   //@item(deepAB, "a.b", "struct{...}", "field")
	a     //@item(deepA, "a", "struct{...}", "var")

	// "a.d" should be ranked above the deeper "a.b.c"
	var i int
	i = a //@complete(re"() \\/\\/", deepAD, deepABC, deepA, deepAB)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/deep2.txt
================================================
This test exercises deep completion.

It was originally bundled with deep.go, but is split into a separate test as
the new marker tests do not permit mutating server options for individual
marks.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- deep/deep2.go --
package deep

type foo struct {
	b bar
}

func (f foo) bar() bar {
	return f.b
}

func (f foo) barPtr() *bar {
	return &f.b
}

type bar struct{}

func (b bar) valueReceiver() int {
	return 0
}

func (b *bar) ptrReceiver() int {
	return 0
}

func _() {
	var (
		i int
		f foo
	)

	f.bar().valueReceiver    //@item(deepBarValue, "f.bar().valueReceiver", "func() int", "method")
	f.barPtr().ptrReceiver   //@item(deepBarPtrPtr, "f.barPtr().ptrReceiver", "func() int", "method")
	f.barPtr().valueReceiver //@item(deepBarPtrValue, "f.barPtr().valueReceiver", "func() int", "method")

	i = fbar //@complete(re"() \\/\\/", deepBarValue, deepBarPtrPtr, deepBarPtrValue)
}

func (b baz) Thing() struct{ val int } {
	return b.thing
}

type baz struct {
	thing struct{ val int }
}

func (b baz) _() {
	b.Thing().val    //@item(deepBazMethVal, "b.Thing().val", "int", "field")
	b.thing.val      //@item(deepBazFieldVal, "b.thing.val", "int", "field")
	var _ int = bval //@rank(re"() \\/\\/", deepBazFieldVal, deepBazMethVal)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/errors.txt
================================================
This test checks completion related to errors.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"deepCompletion": false
}

-- go.mod --
module golang.org/lsptests

go 1.18

-- errors.go --
package errors

import (
	"golang.org/lsptests/types"
)

func _() {
	bob.Bob() //@complete(re"()\\.")
	types.b //@complete(re"() \\/\\/", Bob_interface)
}

-- types/types.go --
package types

type Bob interface { //@item(Bob_interface, "Bob", "interface{...}", "interface")
	Bobby()
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/field_list.txt
================================================
This test checks completion related to field lists.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- field_list.go --
package fieldlist

var myInt int   //@item(flVar, "myInt", "int", "var")
type myType int //@item(flType, "myType", "int", "type")

func (my) _()    {} //@complete(re"()\\) _", flType)
func (my my) _() {} //@complete(re"() my\\)"),complete(re"()\\) _", flType)

func (myType) _() {} //@complete(re"()\\) {", flType)

func (myType) _(my my) {} //@complete(re"() my\\)"),complete(re"()\\) {", flType)

func (myType) _() my {} //@complete(re"() {", flType)

func (myType) _() (my my) {} //@complete(re"() my"),complete(re"()\\) {", flType)

func _() {
	var _ struct {
		//@complete("", flType)
		m my //@complete(re"() my"),complete(re"() \\/\\/", flType)
	}

	var _ interface {
		//@complete("", flType)
		m() my //@complete(re"()\\("),complete(re"() \\/\\/", flType)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/foobarbaz.txt
================================================
This test ports some arbitrary tests from the old marker framework, that were
*mostly* about completion.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false,
	"deepCompletion": false,
	"experimentalPostfixCompletions": false
}

-- go.mod --
module foobar.test

go 1.18

-- foo/foo.go --
package foo //@loc(PackageFoo, "foo"),item(PackageFooItem, "foo", "\"foobar.test/foo\"", "package")

type StructFoo struct { //@loc(StructFooLoc, "StructFoo"), item(StructFoo, "StructFoo", "struct{...}", "struct")
	Value int //@item(Value, "Value", "int", "field")
}

// Pre-set this marker, as we don't have a "source" for it in this package.
/* Error() */ //@item(Error, "Error", "func() string", "method")

func Foo() { //@item(Foo, "Foo", "func()", "func")
	var err error
	err.Error() //@complete(re"()E", Error)
}

func _() {
	var sFoo StructFoo           //@complete(re"()t", StructFoo)
	if x := sFoo; x.Value == 1 { //@complete(re"()V", Value), typedef("sFoo", StructFooLoc)
		return
	}
}

func _() {
	shadowed := 123
	{
		shadowed := "hi" //@item(shadowed, "shadowed", "string", "var")
		sha              //@complete(re"()a", shadowed), diag("sha", re"(undefined|undeclared)")
		_ = shadowed
	}
}

type IntFoo int //@loc(IntFooLoc, "IntFoo"), item(IntFoo, "IntFoo", "int", "type")

-- bar/bar.go --
package bar

import (
	"foobar.test/foo" //@item(foo, "foo", "\"foobar.test/foo\"", "package")
)

func helper(i foo.IntFoo) {} //@item(helper, "helper", "func(i foo.IntFoo)", "func")

func _() {
	help //@complete(re"()l", helper)
	_ = foo.StructFoo{} //@complete(re"()S", IntFoo, StructFoo)
}

// Bar is a function.
func Bar() { //@item(Bar, "Bar", "func()", "func", "Bar is a function.")
	foo.Foo()        //@complete(re"()F", Foo, IntFoo, StructFoo)
	var _ foo.IntFoo //@complete(re"()I", IntFoo, StructFoo)
	foo.()           //@complete(re"()\\(", Foo, IntFoo, StructFoo), diag(")", re"expected type")
}

// These items weren't present in the old marker tests (due to settings), but
// we may as well include them.
//@item(intConversion, "int()"), item(fooFoo, "foo.Foo")
//@item(fooIntFoo, "foo.IntFoo"), item(fooStructFoo, "foo.StructFoo")

func _() {
	var Valentine int //@item(Valentine, "Valentine", "int", "var")

	_ = foo.StructFoo{ //@diag("foo", re"unkeyed fields")
		Valu //@complete(re"() \\/\\/", Value)
	}
  	_ = foo.StructFoo{ //@diag("foo", re"unkeyed fields")
		Va        //@complete(re"()a", Value, Valentine)

	}
	_ = foo.StructFoo{
		Value: 5, //@complete(re"()a", Value)
	}
	_ = foo.StructFoo{
		//@complete(re"()//", Value, Valentine, intConversion, foo, helper, Bar)
	}
	_ = foo.StructFoo{
		Value: Valen //@complete(re"()le", Valentine)
	}
	_ = foo.StructFoo{
		Value:       //@complete(re"() \\/\\/", Valentine, intConversion, foo, helper, Bar)
	}
	_ = foo.StructFoo{
		Value:       //@complete(re"() ", Valentine, intConversion, foo, helper, Bar)
	}
}

-- baz/baz.go --
package baz

import (
	"foobar.test/bar"

	f "foobar.test/foo"
)

var FooStruct f.StructFoo

func Baz() {
	defer bar.Bar() //@complete(re"()B", Bar)
	// TODO: Test completion here.
	defer bar.B //@diag(re"bar.B()", re"must be function call")
	var x f.IntFoo  //@complete(re"()n", IntFoo), typedef("x", IntFooLoc)
	bar.Bar()       //@complete(re"()B", Bar)
}

func _() {
	bob := f.StructFoo{Value: 5}
	if x := bob. //@complete(re"() \\/\\/", Value)
	switch true == false {
		case true:
			if x := bob. //@complete(re"() \\/\\/", Value)
		case false:
	}
	if x := bob.Va //@complete(re"()a", Value)
	switch true == true {
		default:
	}
}

-- arraytype/arraytype.go --
package arraytype

import (
	"foobar.test/foo"
)

func _() {
	var (
		val string //@item(atVal, "val", "string", "var")
	)

	[] //@complete(re"() \\/\\/", atVal, PackageFooItem)

	[]val //@complete(re"() \\/\\/")

	[]foo.StructFoo //@complete(re"() \\/\\/", StructFoo)

	[]foo.StructFoo(nil) //@complete(re"()\\(", StructFoo)

	[]*foo.StructFoo //@complete(re"() \\/\\/", StructFoo)

	[...]foo.StructFoo //@complete(re"() \\/\\/", StructFoo)

	[2][][4]foo.StructFoo //@complete(re"() \\/\\/", StructFoo)

	[]struct { f []foo.StructFoo } //@complete(re"() }", StructFoo)
}

func _() {
	type myInt int //@item(atMyInt, "myInt", "int", "type")

	var mark []myInt //@item(atMark, "mark", "[]myInt", "var")

	var s []myInt //@item(atS, "s", "[]myInt", "var")
	s = []m //@complete(re"() \\/\\/", atMyInt)

	var a [1]myInt
	a = [1]m //@complete(re"() \\/\\/", atMyInt)

	var ds [][]myInt
	ds = [][]m //@complete(re"() \\/\\/", atMyInt)
}

func _() {
	var b [0]byte //@item(atByte, "b", "[0]byte", "var")
	var _ []byte = b //@snippet(re"() \\/\\/", atByte, "b[:]")
}

-- badstmt/badstmt.go --
package badstmt

import (
	"foobar.test/foo"
)

// (The syntax error causes suppression of diagnostics for type errors.
// See issue #59888.)

func _(x int) {
	defer foo.F //@complete(re"() \\/\\/", Foo, IntFoo, StructFoo)
	defer foo.F //@complete(re"() \\/\\/", Foo, IntFoo, StructFoo)
}

func _() {
	switch true {
	case true:
		go foo.F //@complete(re"() \\/\\/", Foo, IntFoo, StructFoo)
	}
}

func _() {
	defer func() {
		foo.F //@complete(re"() \\/\\/", Foo, IntFoo, StructFoo), snippet(re"() \\/\\/", Foo, "Foo()")

		foo. //@rank(re"() \\/\\/", Foo)
	}
}

-- badstmt/badstmt_2.go --
package badstmt

import (
	"foobar.test/foo"
)

func _() {
	defer func() { foo. } //@rank(re"() }", Foo)
}

-- badstmt/badstmt_3.go --
package badstmt

import (
	"foobar.test/foo"
)

func _() {
	go foo. //@rank(re"() \\/\\/", Foo, IntFoo), snippet(re"() \\/\\/", Foo, "Foo()")
}

-- badstmt/badstmt_4.go --
package badstmt

import (
	"foobar.test/foo"
)

func _() {
	go func() {
		defer foo. //@rank(re"() \\/\\/", Foo, IntFoo)
	}
}

-- selector/selector.go --
package selector

import (
	"foobar.test/bar"
)

type S struct {
	B, A, C int //@item(Bf, "B", "int", "field"),item(Af, "A", "int", "field"),item(Cf, "C", "int", "field")
}

func _() {
	_ = S{}.; //@complete(re"();", Af, Bf, Cf)
}

type bob struct { a int } //@item(a, "a", "int", "field")
type george struct { b int }
type jack struct { c int } //@item(c, "c", "int", "field")
type jill struct { d int }

func (b *bob) george() *george {} //@item(george, "george", "func() *george", "method")
func (g *george) jack() *jack {}
func (j *jack) jill() *jill {} //@item(jill, "jill", "func() *jill", "method")

func _() {
	b := &bob{}
	y := b.george().
		jack();
	y.; //@complete(re"();", c, jill)
}

func _() {
	bar. //@complete(re"() \\/", Bar)
	x := 5

	var b *bob
	b. //@complete(re"() \\/", a, george)
	y, z := 5, 6

	b. //@complete(re"() \\/", a, george)
	y, z, a, b, c := 5, 6
}

func _() {
	bar. //@complete(re"() \\/", Bar)
	bar.Bar()

	bar. //@complete(re"() \\/", Bar)
	go f()
}

func _() {
	var b *bob
	if y != b. //@complete(re"() \\/", a, george)
	z := 5

	if z + y + 1 + b. //@complete(re"() \\/", a, george)
	r, s, t := 4, 5

	if y != b. //@complete(re"() \\/", a, george)
	z = 5

	if z + y + 1 + b. //@complete(re"() \\/", a, george)
	r = 4
}

-- literal_snippets/literal_snippets.go --
package literal_snippets

import (
	"bytes"
	"context"
	"go/ast"
	"net/http"
	"sort"

	"golang.org/lsptests/foo"
)

func _() {
	[]int{}        //@item(litIntSlice, "[]int{}", "", "var")
	&[]int{}       //@item(litIntSliceAddr, "&[]int{}", "", "var")
	make([]int, 0) //@item(makeIntSlice, "make([]int, 0)", "", "func")

	var _ *[]int = in //@snippet(re"() \\/\\/", litIntSliceAddr, "&[]int{$0\\}")
	var _ **[]int = in //@complete(re"() \\/\\/")

	var slice []int
	slice = i //@snippet(re"() \\/\\/", litIntSlice, "[]int{$0\\}")
	slice = m //@snippet(re"() \\/\\/", makeIntSlice, "make([]int, ${1:})")
}

func _() {
	type namedInt []int

	namedInt{}        //@item(litNamedSlice, "namedInt{}", "", "var")
	make(namedInt, 0) //@item(makeNamedSlice, "make(namedInt, 0)", "", "func")

	var namedSlice namedInt
	namedSlice = n //@snippet(re"() \\/\\/", litNamedSlice, "namedInt{$0\\}")
	namedSlice = m //@snippet(re"() \\/\\/", makeNamedSlice, "make(namedInt, ${1:})")
}

func _() {
	make(chan int) //@item(makeChan, "make(chan int)", "", "func")

	var ch chan int
	ch = m //@snippet(re"() \\/\\/", makeChan, "make(chan int)")
}

func _() {
	map[string]struct{}{}     //@item(litMap, "map[string]struct{}{}", "", "var")
	make(map[string]struct{}) //@item(makeMap, "make(map[string]struct{})", "", "func")

	var m map[string]struct{}
	m = m //@snippet(re"() \\/\\/", litMap, "map[string]struct{\\}{$0\\}")
	m = m //@snippet(re"() \\/\\/", makeMap, "make(map[string]struct{\\})")

	struct{}{} //@item(litEmptyStruct, "struct{}{}", "", "var")

	m["hi"] = s //@snippet(re"() \\/\\/", litEmptyStruct, "struct{\\}{\\}")
}

func _() {
	type myStruct struct{ i int } //@item(myStructType, "myStruct", "struct{...}", "struct")

	myStruct{}  //@item(litStruct, "myStruct{}", "", "var")
	&myStruct{} //@item(litStructPtr, "&myStruct{}", "", "var")

	var ms myStruct
	ms = m //@snippet(re"() \\/\\/", litStruct, "myStruct{$0\\}")

	var msPtr *myStruct
	msPtr = m //@snippet(re"() \\/\\/", litStructPtr, "&myStruct{$0\\}")

	msPtr = &m //@snippet(re"() \\/\\/", litStruct, "myStruct{$0\\}")

	type myStructCopy struct { i int } //@item(myStructCopyType, "myStructCopy", "struct{...}", "struct")

	// Don't offer literal completion for convertible structs.
	ms = myStruct //@complete(re"() \\/\\/", litStruct, myStructType, myStructCopyType)
}

type myImpl struct{}

func (myImpl) foo() {}

func (*myImpl) bar() {}

type myBasicImpl string

func (myBasicImpl) foo() {}

func _() {
	type myIntf interface {
		foo()
	}

	myImpl{} //@item(litImpl, "myImpl{}", "", "var")

	var mi myIntf
	mi = m //@snippet(re"() \\/\\/", litImpl, "myImpl{\\}")

	myBasicImpl() //@item(litBasicImpl, "myBasicImpl()", "string", "var")

	mi = m //@snippet(re"() \\/\\/", litBasicImpl, "myBasicImpl($0)")

	// only satisfied by pointer to myImpl
	type myPtrIntf interface {
		bar()
	}

	&myImpl{} //@item(litImplPtr, "&myImpl{}", "", "var")

	var mpi myPtrIntf
	mpi = m //@snippet(re"() \\/\\/", litImplPtr, "&myImpl{\\}")
}

func _() {
	var s struct{ i []int } //@item(litSliceField, "i", "[]int", "field")
	var foo []int
	// no literal completions after selector
	foo = s.i //@complete(re"() \\/\\/", litSliceField)
}

func _() {
	type myStruct struct{ i int } //@item(litMyStructType, "myStruct", "struct{...}", "struct")
	myStruct{} //@item(litMyStruct, "myStruct{}", "", "var")

	foo := func(s string, args ...myStruct) {}
	// Don't give literal slice candidate for variadic arg.
	// Do give literal candidates for variadic element.
	foo("", myStruct) //@complete(re"()\\)", litMyStruct, litMyStructType)
}

func _() {
	Buffer{} //@item(litBuffer, "Buffer{}", "", "var")

	var b *bytes.Buffer
	b = bytes.Bu //@snippet(re"() \\/\\/", litBuffer, "Buffer{\\}")
}

func _() {
	_ = "func(...) {}" //@item(litFunc, "func(...) {}", "", "var")

	// no literal "func" completions
	http.Handle("", fun) //@complete(re"()\\)")

	var namedReturn func(s string) (b bool)
	namedReturn = f //@snippet(re"() \\/\\/", litFunc, "func(s string) (b bool) {$0\\}")

	var multiReturn func() (bool, int)
	multiReturn = f //@snippet(re"() \\/\\/", litFunc, "func() (bool, int) {$0\\}")

	var multiNamedReturn func() (b bool, i int)
	multiNamedReturn = f //@snippet(re"() \\/\\/", litFunc, "func() (b bool, i int) {$0\\}")

	var duplicateParams func(myImpl, int, myImpl)
	duplicateParams = f //@snippet(re"() \\/\\/", litFunc, "func(mi1 myImpl, i int, mi2 myImpl) {$0\\}")

	type aliasImpl = myImpl
	var aliasParams func(aliasImpl) aliasImpl
	aliasParams = f //@snippet(re"() \\/\\/", litFunc, "func(ai aliasImpl) aliasImpl {$0\\}")

	const two = 2
	var builtinTypes func([]int, [two]bool, map[string]string, struct{ i int }, interface{ foo() }, <-chan int)
	builtinTypes = f //@snippet(re"() \\/\\/", litFunc, "func(i1 []int, b [2]bool, m map[string]string, s struct{i int\\}, i2 interface{foo()\\}, c <-chan int) {$0\\}")

	var _ func(ast.Node) = f //@snippet(re"() \\/\\/", litFunc, "func(n ast.Node) {$0\\}")
	var _ func(error) = f //@snippet(re"() \\/\\/", litFunc, "func(err error) {$0\\}")
	var _ func(context.Context) = f //@snippet(re"() \\/\\/", litFunc, "func(ctx context.Context) {$0\\}")

	type context struct {}
	var _ func(context) = f //@snippet(re"() \\/\\/", litFunc, "func(ctx context) {$0\\}")
}

func _() {
	float64() //@item(litFloat64, "float64()", "float64", "var")

	// don't complete to "&float64()"
	var _ *float64 = float64 //@complete(re"() \\/\\/")

	var f float64
	f = fl //@complete(re"() \\/\\/", litFloat64),snippet(re"() \\/\\/", litFloat64, "float64($0)")

	type myInt int
	myInt() //@item(litMyInt, "myInt()", "", "var")

	var mi myInt
	mi = my //@snippet(re"() \\/\\/", litMyInt, "myInt($0)")
}

func _() {
	type ptrStruct struct {
		p *ptrStruct
	}

	ptrStruct{} //@item(litPtrStruct, "ptrStruct{}", "", "var")

	ptrStruct{
		p: &ptrSt, //@rank(re"(),", litPtrStruct)
	}

	&ptrStruct{} //@item(litPtrStructPtr, "&ptrStruct{}", "", "var")

	&ptrStruct{
		p: ptrSt, //@rank(re"(),", litPtrStructPtr)
	}
}

func _() {
	f := func(...[]int) {}
	f() //@snippet(re"()\\)", litIntSlice, "[]int{$0\\}")
}


func _() {
	// don't complete to "untyped int()"
	[]int{}[untyped] //@complete(re"()\\] \\/\\/")
}

type Tree[T any] struct{}

func (tree Tree[T]) Do(f func(s T)) {}

func _() {
	var t Tree[string]
	t.Do(fun) //@complete(re"()\\)", litFunc), snippet(re"()\\)", litFunc, "func(s string) {$0\\}")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/func_rank.txt
================================================
This test checks various ranking of completion results within function call
context.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false,
	"deepCompletion": false
}

-- func_rank.go --
package func_rank

import "net/http"

var stringAVar = "var"    //@item(stringAVar, "stringAVar", "string", "var")
func stringBFunc() string { return "str" } //@item(stringBFunc, "stringBFunc", "func() string", "func")
type stringer struct{}    //@item(stringer, "stringer", "struct{...}", "struct")

func _() stringer //@complete(re"()tr", stringer)

func _(val stringer) {} //@complete(re"()tr", stringer)

func (stringer) _() {} //@complete(re"()tr", stringer)

func _() {
	var s struct {
		AA int    //@item(rankAA, "AA", "int", "field")
		AB string //@item(rankAB, "AB", "string", "field")
		AC int    //@item(rankAC, "AC", "int", "field")
	}
	fnStr := func(string) {}
	fnStr(s.A)      //@complete(re"()\\)", rankAB, rankAA, rankAC)
	fnStr("" + s.A) //@complete(re"()\\)", rankAB, rankAA, rankAC)

	fnInt := func(int) {}
	fnInt(-s.A) //@complete(re"()\\)", rankAA, rankAC, rankAB)

	// no expected type
	fnInt(func() int { s.A }) //@complete(re"() }", rankAA, rankAB, rankAC)
	fnInt(s.A())              //@complete(re"()\\(\\)", rankAA, rankAC, rankAB)
	fnInt([]int{}[s.A])       //@complete(re"()\\]\\)", rankAA, rankAC, rankAB)
	fnInt([]int{}[:s.A])      //@complete(re"()\\]\\)", rankAA, rankAC, rankAB)

	fnInt(s.A.(int)) //@complete(re"()\\.\\(", rankAA, rankAC, rankAB)

	fnPtr := func(*string) {}
	fnPtr(&s.A) //@complete(re"()\\)", rankAB, rankAA, rankAC)

	var aaPtr *string //@item(rankAAPtr, "aaPtr", "*string", "var")
	var abPtr *int    //@item(rankABPtr, "abPtr", "*int", "var")
	fnInt(*a)         //@complete(re"()\\)", rankABPtr, rankAAPtr, stringAVar)

	_ = func() string {
		return s.A //@complete(re"() \\/\\/", rankAB, rankAA, rankAC)
	}
}

type foo struct {
	fooPrivateField int //@item(rankFooPrivField, "fooPrivateField", "int", "field")
	FooPublicField  int //@item(rankFooPubField, "FooPublicField", "int", "field")
}

func (foo) fooPrivateMethod() int { //@item(rankFooPrivMeth, "fooPrivateMethod", "func() int", "method")
	return 0
}

func (foo) FooPublicMethod() int { //@item(rankFooPubMeth, "FooPublicMethod", "func() int", "method")
	return 0
}

func _() {
	var _ int = foo{}. //@rank(re"() \\/\\/", rankFooPrivField, rankFooPubField),rank(re"() \\/\\/", rankFooPrivMeth, rankFooPubMeth),rank(re"() \\/\\/", rankFooPrivField, rankFooPrivMeth)
}

func _() {
	HandleFunc //@item(httpHandleFunc, "HandleFunc", "func(pattern string, handler func(http.ResponseWriter, *http.Request))", "func")
	HandlerFunc //@item(httpHandlerFunc, "HandlerFunc", "func(http.ResponseWriter, *http.Request)", "type")

	http.HandleFunc //@rank(re"() \\/\\/", httpHandleFunc, httpHandlerFunc)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/func_sig.txt
================================================
This test checks completion related to function signatures.

-- flags --
-ignore_extra_diags

-- func_sig.go --
package funcsig

type someType int //@item(sigSomeType, "someType", "int", "type")

// Don't complete "foo" in signature.
func (foo someType) _() { //@item(sigFoo, "foo", "someType", "var"),complete(re"()\\) {", sigSomeType)

	//@complete("", sigFoo, sigSomeType)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/func_snippets.txt
================================================
This test exercises function snippets using generics.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": true
}

-- go.mod --
module golang.org/lsptests/snippets

go 1.18

-- funcsnippets.go --
package snippets

type SyncMap[K comparable, V any] struct{}

func NewSyncMap[K comparable, V any]() (result *SyncMap[K, V]) { //@item(NewSyncMap, "NewSyncMap", "", "")
	return
}

func Identity[P ~int](p P) P { //@item(Identity, "Identity", "", "")
	return p
}

func _() {
	_ = NewSyncM //@snippet(re"() \\/\\/", NewSyncMap, "NewSyncMap[${1:K comparable}, ${2:V any}]()")
	_ = Identi //@snippet(re"() \\/\\/", Identity, "Identity(${1:p P})")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/func_value.txt
================================================
This test checks completion related to function values.

-- flags --
-ignore_extra_diags

-- func_value.go --
package funcvalue

func fooFunc() int { //@item(fvFooFunc, "fooFunc", "func() int", "func")
	return 0
}

var _ = fooFunc() //@item(fvFooFuncCall, "fooFunc", "func() int", "func")

var fooVar = func() int { //@item(fvFooVar, "fooVar", "func() int", "var")
	return 0
}

var _ = fooVar() //@item(fvFooVarCall, "fooVar", "func() int", "var")

type myFunc func() int

var fooType myFunc = fooVar //@item(fvFooType, "fooType", "myFunc", "var")

var _ = fooType() //@item(fvFooTypeCall, "fooType", "func() int", "var")

func _() {
	var f func() int
	f = foo //@complete(re"() \\/\\/", fvFooFunc, fvFooType, fvFooVar)

	var i int
	i = foo //@complete(re"() \\/\\/", fvFooFuncCall, fvFooTypeCall, fvFooVarCall)
}

-- generic/func_value.go --
package funcvalue

type bar struct{}

func (b bar) Num() int {
	return 0
}

func Bar[T any]() bar {
	return bar{}
}

func BarWithArg[T any](a int) bar {
	return bar{}
}

func (b bar) Bar2() bar {
	return b
}

func _() {
	Bar[T].Num //@item(bar, "Bar[T]().Num", "func() int", "method")
	Bar[T].Bar2().Num //@item(bar2, "Bar[T]().Bar2().Num", "func() int", "method")
	var i int
	i = Num //@complete(re"() \\/\\/", bar, bar2)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/fuzzy.txt
================================================
This test exercises fuzzy completion matching.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- fuzzy/fuzzy.go --
package fuzzy

func _() {
	var a struct {
		fabar  int
		fooBar string
	}

	a.fabar  //@item(fuzzFabarField, "a.fabar", "int", "field")
	a.fooBar //@item(fuzzFooBarField, "a.fooBar", "string", "field")

	afa //@complete(re"() \\/\\/", fuzzFabarField, fuzzFooBarField)
	afb //@complete(re"() \\/\\/", fuzzFooBarField, fuzzFabarField)

	fab //@complete(re"() \\/\\/", fuzzFabarField)

	var myString string
	myString = af //@complete(re"() \\/\\/", fuzzFooBarField, fuzzFabarField)

	var b struct {
		c struct {
			d struct {
				e struct {
					abc string
				}
				abc float32
			}
			abc bool
		}
		abc int
	}

	b.abc       //@item(fuzzABCInt, "b.abc", "int", "field")
	b.c.abc     //@item(fuzzABCbool, "b.c.abc", "bool", "field")
	b.c.d.abc   //@item(fuzzABCfloat, "b.c.d.abc", "float32", "field")
	b.c.d.e.abc //@item(fuzzABCstring, "b.c.d.e.abc", "string", "field")

	// in depth order by default
	abc //@complete(re"() \\/\\/", fuzzABCInt, fuzzABCbool, fuzzABCfloat)

	// deep candidate that matches expected type should still ranked first
	var s string
	s = abc //@complete(re"() \\/\\/", fuzzABCstring, fuzzABCInt, fuzzABCbool)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/imported-std.txt
================================================
Test of imported completions respecting the effective Go version of the file.

(See "un-" prefixed file for same test of unimported completions.)

These symbols below were introduced to go/types in go1.22:

  Alias
  Info.FileVersions
  (Checker).PkgNameOf

The underlying logic depends on versions.FileVersion, which only
behaves correctly in go1.22. (When go1.22 is assured, we can remove
the min_go flag but leave the test inputs unchanged.)

-- flags --
-ignore_extra_diags
-min_go_command=go1.22

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

import "go/ast"
import "go/token"
import "go/types"

// package-level decl
var _ = types.Sat //@rank(re"()Sat", "Satisfies")
var _ = types.Ali //@rank(re"()Ali", "!Alias")

// field
var _ = new(types.Info).Use //@rank(re"()Use", "Uses")
var _ = new(types.Info).Fil //@rank(re"()Fil", "!FileVersions")

// method
var _ = new(types.Checker).Obje //@rank(re"()Obje", "ObjectOf")
var _ = new(types.Checker).PkgN //@rank(re"()PkgN", "!PkgNameOf")

-- b/b.go --
//go:build go1.22

package a

import "go/ast"
import "go/token"
import "go/types"

// package-level decl
var _ = types.Sat //@rank(re"()Sat", "Satisfies")
var _ = types.Ali //@rank(re"()Ali", "Alias")

// field
var _ = new(types.Info).Use //@rank(re"()Use", "Uses")
var _ = new(types.Info).Fil //@rank(re"()Fil", "FileVersions")

// method
var _ = new(types.Checker).Obje //@rank(re"()Obje", "ObjectOf")
var _ = new(types.Checker).PkgN //@rank(re"()PkgN", "PkgNameOf")


================================================
FILE: gopls/internal/test/marker/testdata/completion/index.txt
================================================
This test checks completion related to index expressions.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- index.go --
package index

func _() {
	var (
		aa = "123" //@item(indexAA, "aa", "string", "var")
		ab = 123   //@item(indexAB, "ab", "int", "var")
	)

	var foo [1]int
	foo[a]  //@complete(re"()\\]", indexAB, indexAA)
	foo[:a] //@complete(re"()\\]", indexAB, indexAA)
	a[:a]   //@complete(re"()\\[", indexAA, indexAB)
	a[a]    //@complete(re"()\\[", indexAA, indexAB)

	var bar map[string]int
	bar[a] //@complete(re"()\\]", indexAA, indexAB)

	type myMap map[string]int
	var baz myMap
	baz[a] //@complete(re"()\\]", indexAA, indexAB)

	type myInt int
	var mi myInt //@item(indexMyInt, "mi", "myInt", "var")
	foo[m]       //@snippet(re"()\\]", indexMyInt, "mi")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/interfacerank.txt
================================================
This test checks that completion ranking accounts for interface assignability.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false,
	"deepCompletion": false
}

-- p.go --

package interfacerank

type foo interface {
	foo()
}

type fooImpl int

func (*fooImpl) foo() {}

func wantsFoo(foo) {}

func _() {
	var (
		aa string   //@item(irAA, "aa", "string", "var")
		ab *fooImpl //@item(irAB, "ab", "*fooImpl", "var")
	)

	wantsFoo(a) //@complete(re"()\\)", irAB, irAA)

	var ac fooImpl //@item(irAC, "ac", "fooImpl", "var")
	wantsFoo(&a)   //@complete(re"()\\)", irAC, irAA, irAB)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue51783.txt
================================================
Regression test for "completion gives unneeded generic type
instantiation snippet", #51783.

Type parameters that can be inferred from the arguments
are not part of the offered completion snippet.

-- flags --
-ignore_extra_diags

-- a.go --
package a

// identity has a single simple type parameter.
// The completion omits the instantiation.
func identity[T any](x T) T

// clone has a second type parameter that is nonetheless constrained by the parameter.
// The completion omits the instantiation.
func clone[S ~[]E, E any](s S) S

// unconstrained has a type parameter constrained only by the result.
// The completion suggests instantiation.
func unconstrained[X, Y any](x X) Y

// partial has three type parameters,
// only the last two of which may be omitted as they
// are constrained by the arguments.
func partial[R any, S ~[]E, E any](s S) R

//@item(identity, "identity", "details", "kind")
//@item(clone, "clone", "details", "kind")
//@item(unconstrained, "unconstrained", "details", "kind")
//@item(partial, "partial", "details", "kind")

func _() {
	_ = identity //@snippet(re"()identity", identity, "identity(${1:})")

	_ = clone //@snippet(re"()clone", clone, "clone(${1:})")

	_ = unconstrained //@snippet(re"()unconstrained", unconstrained, "unconstrained[${1:}](${2:})")

	_ = partial //@snippet(re"()partial", partial, "partial[${1:}](${2:})")

	// Result-type inference permits us to omit Y in this (rare) case,
	// but completion doesn't support that.
	var _ int = unconstrained //@snippet(re"()unconstrained", unconstrained, "unconstrained[${1:}](${2:})")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue56505.txt
================================================
Test for golang/go#56505: completion on variables of type *error should not
panic.

-- flags --
-ignore_extra_diags

-- issue.go --
package issues

func _() {
	var e *error
	e.x //@complete(re"() \\/\\/")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue59096.txt
================================================
This test exercises the panic in golang/go#59096: completing at a syntactic
type-assert expression was panicking because gopls was translating it into
a (malformed) selector expr.

-- settings.json --
{
	"importsSource": "gopls"
}

-- go.mod --
module example.com

-- a/a.go --
package a

func _() {
	b.(foo) //@complete(re"b.()", B), diag("b", re"(undefined|undeclared name): b")
}

//@item(B, "B", "const (from \"example.com/b\")", "const")

-- b/b.go --
package b

const B = 0


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue60545.txt
================================================
This test checks that unimported completion is case-insensitive.

-- go.mod --
module mod.test

go 1.18

-- settings.json --
{
	"importsSource": "gopls"
}

-- main.go --
package main

//@item(Print, "Print", "func (from \"fmt\")", "func")
//@item(Printf, "Printf", "func (from \"fmt\")", "func")
//@item(Println, "Println", "func (from \"fmt\")", "func")

func main() {
	fmt.p //@complete(re"fmt.p()", Print, Printf, Println), diag("fmt", re"(undefined|undeclared)")
}

-- other.go --
package main

// Including another package that imports "fmt" causes completion to use the
// existing metadata, which is the codepath leading to golang/go#60545.
import "fmt"

func _() {
	fmt.Println()
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue62141.txt
================================================
This test checks that we don't suggest completion to an untyped conversion such
as "untyped float(abcdef)".

-- main.go --
package main

func main() {
	abcdef := 32 //@diag("abcdef", re"not used")
	x := 1.0 / abcd //@acceptcompletion(re"abcd()", "abcdef", int), diag("x", re"not used"), diag("abcd", re"(undefined|undeclared)")

	// Verify that we don't suggest converting compatible untyped constants.
	const untypedConst = 42
	y := 1.1 / untypedC //@acceptcompletion(re"untypedC()", "untypedConst", untyped), diag("y", re"not used"), diag("untypedC", re"(undefined|undeclared)")
}

-- @int/main.go --
package main

func main() {
	abcdef := 32 //@diag("abcdef", re"not used")
	x := 1.0 / float64(abcdef) //@acceptcompletion(re"abcd()", "abcdef", int), diag("x", re"not used"), diag("abcd", re"(undefined|undeclared)")

	// Verify that we don't suggest converting compatible untyped constants.
	const untypedConst = 42
	y := 1.1 / untypedC //@acceptcompletion(re"untypedC()", "untypedConst", untyped), diag("y", re"not used"), diag("untypedC", re"(undefined|undeclared)")
}

-- @untyped/main.go --
package main

func main() {
	abcdef := 32 //@diag("abcdef", re"not used")
	x := 1.0 / abcd //@acceptcompletion(re"abcd()", "abcdef", int), diag("x", re"not used"), diag("abcd", re"(undefined|undeclared)")

	// Verify that we don't suggest converting compatible untyped constants.
	const untypedConst = 42
	y := 1.1 / untypedConst //@acceptcompletion(re"untypedC()", "untypedConst", untyped), diag("y", re"not used"), diag("untypedC", re"(undefined|undeclared)")
}



================================================
FILE: gopls/internal/test/marker/testdata/completion/issue62560.txt
================================================
This test verifies that completion of package members in unimported packages
reflects their fuzzy score, even when those members are present in the
transitive import graph of the main module. (For technical reasons, this was
the nature of the regression in golang/go#62560.)

-- go.mod --
module mod.test

-- foo/foo.go --
package foo

func _() {
	json.U //@rank(re"U()", "Unmarshal", "InvalidUTF8Error"), diag("json", re"(undefined|undeclared)")
}

-- bar/bar.go --
package bar

import _ "encoding/json"


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue62676.txt
================================================
This test verifies that unimported completion respects the usePlaceholders setting.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": false
}

-- go.mod --
module mod.test

go 1.21

-- foo/foo.go --
package foo

func _() {
	// This uses goimports-based completion; TODO: this should insert snippets.
	os.Open //@acceptcompletion(re"Open()", "Open", open)
}

func _() {
	// This uses metadata-based completion.
	errors.New //@acceptcompletion(re"New()", "New", new)
}

-- bar/bar.go --
package bar

import _ "errors" // important: doesn't transitively import os.

-- @new/foo/foo.go --
package foo

import "errors"

func _() {
	// This uses goimports-based completion; TODO: this should insert snippets.
	os.Open //@acceptcompletion(re"Open()", "Open", open)
}

func _() {
	// This uses metadata-based completion.
	errors.New(${1:}) //@acceptcompletion(re"New()", "New", new)
}

-- @open/foo/foo.go --
package foo

import "os"

func _() {
	// This uses goimports-based completion; TODO: this should insert snippets.
	os.Open(${1:}) //@acceptcompletion(re"Open()", "Open", open)
}

func _() {
	// This uses metadata-based completion.
	errors.New //@acceptcompletion(re"New()", "New", new)
}



================================================
FILE: gopls/internal/test/marker/testdata/completion/issue70636.txt
================================================
This test reproduces the crash of golang/go#70636, an out of bounds error when
analyzing a return statement with more results than the signature expects.

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com

go 1.21

-- p.go --
package p

var xx int
var xy string


func _() {
	return Foo(x) //@ rank(re"x()", "xx", "xy")
}

func Foo[T any](t T) T {}


================================================
FILE: gopls/internal/test/marker/testdata/completion/issue72753.txt
================================================
This test checks that completion gives correct completion for
incomplete AssignStmt with multiple left-hand vars.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": false
}

-- go.mod --
module mod.test

go 1.21

-- string.go --
package a

func _(left, right string){
	left, ri //@acceptcompletion(re"ri()", "right", string)
}

-- @string/string.go --
package a

func _(left, right string){
	left, right //@acceptcompletion(re"ri()", "right", string)
}

-- array.go --
package a
func _(right string) {
	var left [3]int
	left[0], ri //@acceptcompletion(re"ri()", "right", array)
}

-- @array/array.go --
package a
func _(right string) {
	var left [3]int
	left[0], right //@acceptcompletion(re"ri()", "right", array)
}

-- slice.go --
package a
func _(right string) {
	var left []int
	left[0], ri //@acceptcompletion(re"ri()", "right", slice)
}

-- @slice/slice.go --
package a
func _(right string) {
	var left []int
	left[0], right //@acceptcompletion(re"ri()", "right", slice)
}

-- map.go --
package a
func _(right string) {
	var left map[int]int
	left[0], ri //@acceptcompletion(re"ri()", "right", map)
}

-- @map/map.go --
package a
func _(right string) {
	var left map[int]int
	left[0], right //@acceptcompletion(re"ri()", "right", map)
}

-- star.go --
package a
func _(right string) {
	var left *int
	*left, ri //@acceptcompletion(re"ri()", "right", star)
}

-- @star/star.go --
package a
func _(right string) {
	var left *int
	*left, right //@acceptcompletion(re"ri()", "right", star)
}



================================================
FILE: gopls/internal/test/marker/testdata/completion/keywords.txt
================================================
This test checks completion of Go keywords.

-- flags --
-ignore_extra_diags
-filter_keywords=false

-- settings.json --
{
	"completeUnimported": false,
	"matcher": "caseInsensitive",
	"experimentalPostfixCompletions": false
}

-- keywords.go --
package keywords

//@rank("", type),rank("", func),rank("", var),rank("", const),rank("", import)

func _() {
	var test int //@rank(re"() \\/\\/", int, interface)
	var tChan chan int
	var _ m //@complete(re"() \\/\\/", map)
	var _ f //@complete(re"() \\/\\/", func)
	var _ c //@complete(re"() \\/\\/", chan)

	var _ str //@rank(re"() \\/\\/", string, struct)

	type _ int //@rank(re"() \\/\\/", interface, int)

	type _ str //@rank(re"() \\/\\/", struct, string)

	switch test {
	case 1: // TODO: trying to complete case here will break because the parser won't return *ast.Ident
		b //@complete(re"() \\/\\/", break)
	case 2:
		f //@complete(re"() \\/\\/", fallthrough, for)
		r //@complete(re"() \\/\\/", return)
		d //@complete(re"() \\/\\/", default, defer)
		c //@complete(re"() \\/\\/", case, const)
	}

	switch test.(type) {
	case fo: //@complete(re"():")
	case int:
		b //@complete(re"() \\/\\/", break)
	case int32:
		f //@complete(re"() \\/\\/", for)
		d //@complete(re"() \\/\\/", default, defer)
		r //@complete(re"() \\/\\/", return)
		c //@complete(re"() \\/\\/", case, const)
	}

	select {
	case <-tChan:
		b //@complete(re"() \\/\\/", break)
		c //@complete(re"() \\/\\/", case, const)
	}

	for index := 0; index < test; index++ {
		c //@complete(re"() \\/\\/", const, continue)
		b //@complete(re"() \\/\\/", break)
	}

	for range []int{} {
		c //@complete(re"() \\/\\/", const, continue)
		b //@complete(re"() \\/\\/", break)
	}

	// Test function level keywords

	//Using 2 characters to test because map output order is random
	sw //@complete(re"() \\/\\/", switch)
	se //@complete(re"() \\/\\/", select)

	f //@complete(re"() \\/\\/", for)
	d //@complete(re"() \\/\\/", defer)
	g //@rank(re"() \\/\\/", go),rank(re"() \\/\\/", goto)
	r //@complete(re"() \\/\\/", return)
	i //@complete(re"() \\/\\/", if)
	e //@complete(re"() \\/\\/", else)
	v //@complete(re"() \\/\\/", var)
	c //@complete(re"() \\/\\/", const)

	for i := r //@complete(re"() \\/\\/", range)
}

/* package */ //@item(package, "package", "", "keyword")
/* import */ //@item(import, "import", "", "keyword")
/* func */ //@item(func, "func", "", "keyword")
/* type */ //@item(type, "type", "", "keyword")
/* var */ //@item(var, "var", "", "keyword")
/* const */ //@item(const, "const", "", "keyword")
/* break */ //@item(break, "break", "", "keyword")
/* default */ //@item(default, "default", "", "keyword")
/* case */ //@item(case, "case", "", "keyword")
/* defer */ //@item(defer, "defer", "", "keyword")
/* go */ //@item(go, "go", "", "keyword")
/* for */ //@item(for, "for", "", "keyword")
/* if */ //@item(if, "if", "", "keyword")
/* else */ //@item(else, "else", "", "keyword")
/* switch */ //@item(switch, "switch", "", "keyword")
/* select */ //@item(select, "select", "", "keyword")
/* fallthrough */ //@item(fallthrough, "fallthrough", "", "keyword")
/* continue */ //@item(continue, "continue", "", "keyword")
/* return */ //@item(return, "return", "", "keyword")
/* goto */ //@item(goto, "goto", "", "keyword")
/* struct */ //@item(struct, "struct", "", "keyword")
/* interface */ //@item(interface, "interface", "", "keyword")
/* map */ //@item(map, "map", "", "keyword")
/* chan */ //@item(chan, "chan", "", "keyword")
/* range */ //@item(range, "range", "", "keyword")
/* string */ //@item(string, "string", "", "type")
/* int */ //@item(int, "int", "", "type")

-- accidental_keywords.go --
package keywords

// non-matching candidate - shouldn't show up as completion
var apple = "apple"

func _() {
	foo.bar() // insert some extra statements to exercise our AST surgery
	variance := 123 //@item(kwVariance, "variance", "int", "var")
	foo.bar()
	println(var) //@complete(re"()\\)", kwVariance)
}

func _() {
	foo.bar()
	var s struct { variance int } //@item(kwVarianceField, "variance", "int", "field")
	foo.bar()
	s.var //@complete(re"() \\/\\/", kwVarianceField)
}

func _() {
	channel := 123 //@item(kwChannel, "channel", "int", "var")
	chan //@complete(re"() \\/\\/", kwChannel)
	foo.bar()
}

func _() {
	foo.bar()
	var typeName string //@item(kwTypeName, "typeName", "string", "var")
	foo.bar()
	type //@complete(re"() \\/\\/", kwTypeName)
}
-- empty_select.go --
package keywords

func _() {
	select {
		c //@complete(re"() \\/\\/", case)
	}
}
-- empty_switch.go --
package keywords

func _() {
	switch {
		//@complete("", case, default)
	}

	switch test.(type) {
		d //@complete(re"() \\/\\/", default)
	}
}

-- default_name_var_switch.go --
package keywords

func _() {
	var defaultVar int //@item(defaultVar, "defaultVar", "int", "var")
	switch defaultVar {
		case 1:
			println("helloworld")
		d //@complete(re"() \\/\\/", default, defaultVar, defer)
	}
	switch defaultVar {
		default:
		d //@complete(re"() \\/\\/", defaultVar, defer)
	}
	var nested int
	switch defaultVar {
		case 1:
			switch nested {
				default:
					println("")
			}
		d //@complete(re"() \\/\\/", default, defaultVar, defer)
	}
}

-- return_different_func.go --
package keywords

/* return  */ //@item(returnWithSpace, "return ", "", "keyword")


func _ () int {
	r //@complete(re"() \\/\\/", returnWithSpace)
}

func _ () (int, int) {
	r //@complete(re"() \\/\\/", returnWithSpace)
}

func _ () (_ int) {
	r //@complete(re"() \\/\\/", returnWithSpace)
}

func _ () (_ int) {
	r //@complete(re"() \\/\\/", returnWithSpace)
}

func _ () (_, _ int) {
	r //@complete(re"() \\/\\/", returnWithSpace)
}

func _ () (_, a int) {
	r //@complete(re"() \\/\\/", return)
}

func _ () {
	r //@complete(re"() \\/\\/", return)
}

func _ () (a int) {
	r //@complete(re"() \\/\\/", return)
}

func _ () (a, b int) {
	r //@complete(re"() \\/\\/", return)
}

func _ () (a, b int, c string) {
	r //@complete(re"() \\/\\/", return)
}

func _ () (a int) {
	_ = func (){
		r //@complete(re"() \\/\\/", return)
	}
	return
}

func _ () int {
	_ = func () (a int) {
		// func lit will be affected by outer function.
		r //@complete(re"() \\/\\/", returnWithSpace)
	}
	return
}

func _ () {
	_ = func () int {
		// func lit will be affected by outer function.
		r //@complete(re"() \\/\\/", return)
	}
	return
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/labels.txt
================================================
This test checks completion of labels.

-- flags --
-ignore_extra_diags

-- labels.go --
package labels

func _() {
	goto F //@complete(re"() \\/\\/", label1, label5)

Foo1: //@item(label1, "Foo1", "label", "const")
	for a, b := range []int{} {
	Foo2: //@item(label2, "Foo2", "label", "const")
		switch {
		case true:
			break F //@complete(re"() \\/\\/", label2, label1)

			continue F //@complete(re"() \\/\\/", label1)

			{
			FooUnjumpable:
			}

			goto F //@complete(re"() \\/\\/", label1, label2, label4, label5)

			func() {
				goto F //@complete(re"() \\/\\/", label3)

				break F //@complete(re"() \\/\\/")

				continue F //@complete(re"() \\/\\/")

			Foo3: //@item(label3, "Foo3", "label", "const")
			}()
		}

	Foo4: //@item(label4, "Foo4", "label", "const")
		switch any(a).(type) {
		case int:
			break F //@complete(re"() \\/\\/", label4, label1)
		}
	}

	break F //@complete(re"() \\/\\/")

	continue F //@complete(re"() \\/\\/")

Foo5: //@item(label5, "Foo5", "label", "const")
	for {
		break F //@complete(re"() \\/\\/", label5)
	}

	return
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/lit.txt
================================================

-- flags --
-ignore_extra_diags

-- go.mod --
module mod.test

go 1.18

-- foo/foo.go --
package foo

type StructFoo struct{ F int }

-- a.go --
package a

import "mod.test/foo"

func _() {
	StructFoo{} //@item(litStructFoo, "StructFoo{}", "struct{...}", "struct")

	var sfp *foo.StructFoo
	// Don't insert the "&" before "StructFoo{}".
	sfp = foo.Str //@snippet(re"() \\/\\/", litStructFoo, "StructFoo{$0\\}")

	var sf foo.StructFoo
	sf = foo.Str //@snippet(re"() \\/\\/", litStructFoo, "StructFoo{$0\\}")
	sf = foo. //@snippet(re"() \\/\\/", litStructFoo, "StructFoo{$0\\}")
}

-- http.go --
package a

import (
	"net/http"
	"sort"
)

func _() {
	sort.Slice(nil, fun) //@snippet(re"()\\)", litFunc, "func(i, j int) bool {$0\\}")

	http.HandleFunc("", f) //@snippet(re"()\\)", litFunc, "func(w http.ResponseWriter, r *http.Request) {$0\\}")

	//@item(litFunc, "func(...) {}", "", "var")
	http.HandlerFunc() //@item(handlerFunc, "http.HandlerFunc()", "", "var")
	http.Handle("", http.HandlerFunc()) //@snippet(re"()\\)\\)", litFunc, "func(w http.ResponseWriter, r *http.Request) {$0\\}")
	http.Handle("", h) //@snippet(re"()\\)", handlerFunc, "http.HandlerFunc($0)")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/maps.txt
================================================
This test checks completion of map keys and values.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- maps.go --
package maps

func _() {
	var aVar int          //@item(mapVar, "aVar", "int", "var")

	// not comparabale
	type aSlice []int     //@item(mapSliceType, "aSlice", "[]int", "type")

	*aSlice     //@item(mapSliceTypePtr, "*aSlice", "[]int", "type")

	// comparable
	type aStruct struct{} //@item(mapStructType, "aStruct", "struct{...}", "struct")

	map[]a{} //@complete(re"()\\]", mapSliceType, mapStructType),snippet(re"()]", mapSliceType, "*aSlice")

	map[a]a{} //@complete(re"()\\]", mapSliceType, mapStructType)
	map[a]a{} //@complete(re"(){", mapSliceType, mapStructType)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/multi_return.txt
================================================
This test checks various ranking of completion results related to functions
with multiple return values.

-- flags --
-ignore_extra_diags

-- multireturn.go --
package multireturn

func f0() {} //@item(multiF0, "f0", "func()", "func")

func f1(int) int { return 0 } //@item(multiF1, "f1", "func(int) int", "func")

func f2(int, int) (int, int) { return 0, 0 } //@item(multiF2, "f2", "func(int, int) (int, int)", "func")

func f2Str(string, string) (string, string) { return "", "" } //@item(multiF2Str, "f2Str", "func(string, string) (string, string)", "func")

func f3(int, int, int) (int, int, int) { return 0, 0, 0 } //@item(multiF3, "f3", "func(int, int, int) (int, int, int)", "func")

func _() {
	_ := f //@rank(re"() \\/\\/", multiF1, multiF2)

	_, _ := f //@rank(re"() \\/\\/", multiF2, multiF0),rank(re"() \\/\\/", multiF1, multiF0)

	_, _ := _, f //@rank(re"() \\/\\/", multiF1, multiF2),rank(re"() \\/\\/", multiF1, multiF0)

	_, _ := f, abc //@rank(re"(), abc", multiF1, multiF2)

	f1()     //@rank(re"()\\)", multiF1, multiF0)
	f1(f)    //@rank(re"()\\)", multiF1, multiF2)
	f2(f)    //@rank(re"()\\)", multiF2, multiF3),rank(re"()\\)", multiF1, multiF3)
	f2(1, f) //@rank(re"()\\)", multiF1, multiF2),rank(re"()\\)", multiF1, multiF0)
	f2(1, )  //@rank(re"()\\)", multiF1, multiF2),rank(re"()\\)", multiF1, multiF0)
	f2Str()  //@rank(re"()\\)", multiF2Str, multiF2)

	var i int
	i, _ := f //@rank(re"() \\/\\/", multiF2, multiF2Str)

	var s string
	_, s := f //@rank(re"() \\/\\/", multiF2Str, multiF2)

	banana, s = f //@rank(re"() \\/\\/", multiF2, multiF3)

	var variadic func(int, ...int)
	variadic() //@rank(re"()\\)", multiF1, multiF0),rank(re"()\\)", multiF2, multiF0),rank(re"()\\)", multiF3, multiF0)
}

func _() {
	var baz func(...any)

	var otterNap func() (int, int) //@item(multiTwo, "otterNap", "func() (int, int)", "var")
	var one int                    //@item(multiOne, "one", "int", "var")

	baz(on) //@rank(re"()\\)", multiOne, multiTwo)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/nested_complit.txt
================================================
This test checks completion of nested composite literals;

Parser recovery changed in Go 1.20, so this test requires at least that
version for consistency.

-- flags --
-ignore_extra_diags

-- nested_complit.go --
package nested_complit

type ncFoo struct {} //@item(structNCFoo, "ncFoo", "struct{...}", "struct")

type ncBar struct { //@item(structNCBar, "ncBar", "struct{...}", "struct")
	baz []ncFoo
}

func _() {
	_ = []ncFoo{} //@item(litNCFoo, "[]ncFoo{}", "", "var")
	_ = make([]ncFoo, 0) //@item(makeNCFoo, "make([]ncFoo, 0)", "", "func")

	_ := ncBar{
		baz: [] //@complete(re"() \\/\\/", litNCFoo, makeNCFoo, structNCBar, structNCFoo)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/postfix.txt
================================================
These tests check that postfix completions do and do not show up in certain
cases. Tests for the postfix completion contents are implemented as ad-hoc
integration tests.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/snippets

go 1.18

-- postfix.go --
package snippets

import (
	"strconv"
)

func _() {
	var foo []int
	foo.append //@rank(re"() \\/\\/", postfixAppend)

	[]int{}.append //@complete(re"() \\/\\/")

	[]int{}.last //@complete(re"() \\/\\/")


	foo.copy //@rank(re"() \\/\\/", postfixCopy)

	var s struct{ i []int }
	s.i.copy //@rank(re"() \\/\\/", postfixCopy)

	var _ []int = s.i.copy //@complete(re"() \\/\\/")

	var blah func() []int
	blah().append //@complete(re"() \\/\\/")
}

func _() {
	/* append! */ //@item(postfixAppend, "append!", "append and re-assign slice", "snippet")
	/* copy! */ //@item(postfixCopy, "copy!", "duplicate slice", "snippet")
	/* for! */ //@item(postfixFor, "for!", "range over slice by index", "snippet")
	/* forr! */ //@item(postfixForr, "forr!", "range over slice by index and value", "snippet")
	/* last! */ //@item(postfixLast, "last!", "s[len(s)-1]", "snippet")
	/* len! */ //@item(postfixLen, "len!", "len(s)", "snippet")
	/* print! */ //@item(postfixPrint, "print!", "print to stdout", "snippet")
	/* range! */ //@item(postfixRange, "range!", "range over slice", "snippet")
	/* reverse! */ //@item(postfixReverse, "reverse!", "reverse slice", "snippet")
	/* sort! */ //@item(postfixSort, "sort!", "sort.Slice()", "snippet")
	/* var! */ //@item(postfixVar, "var!", "assign to variable", "snippet")
	/* ifnotnil! */ //@item(postfixIfNotNil, "ifnotnil!", "if expr != nil", "snippet")

	var foo []int
	foo. //@complete(re"() \\/\\/", postfixAppend, postfixCopy, postfixFor, postfixForr, postfixIfNotNil, postfixLast, postfixLen, postfixPrint, postfixRange, postfixReverse, postfixSort, postfixVar)
	foo = nil

	foo.append //@snippet(re"() \\/\\/", postfixAppend, "foo = append(foo, $0)")
	foo.copy //snippet(re"() \\/\\/", postfixCopy, "fooCopy := make([]int, len(foo))\ncopy($fooCopy, foo)\n")
	foo.fo //@snippet(re"() \\/\\/", postfixFor, "for ${1:} := range foo {\n\t$0\n}")
	foo.forr //@snippet(re"() \\/\\/", postfixForr, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
	foo.last //@snippet(re"() \\/\\/", postfixLast, "foo[len(foo)-1]")
	foo.len //@snippet(re"() \\/\\/", postfixLen, "len(foo)")
	foo.print //@snippet(re"() \\/\\/", postfixPrint, `fmt.Printf("foo: %v\n", foo)`)
	foo.rang //@snippet(re"() \\/\\/", postfixRange, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
	foo.reverse //@snippet(re"() \\/\\/", postfixReverse, "slices.Reverse(foo)")
	foo.sort //@snippet(re"() \\/\\/", postfixSort, "sort.Slice(foo, func(i, j int) bool {\n\t$0\n})")
	foo.va //@snippet(re"() \\/\\/", postfixVar, "${1:} := foo")
	foo.ifnotnil //@snippet(re"() \\/\\/", postfixIfNotNil, "if foo != nil {\n\t$0\n}")
}

func _() {
	/* for! */ //@item(postfixForMap, "for!", "range over map by key", "snippet")
	/* forr! */ //@item(postfixForrMap, "forr!", "range over map by key and value", "snippet")
	/* range! */ //@item(postfixRangeMap, "range!", "range over map", "snippet")
	/* clear! */ //@item(postfixClear, "clear!", "clear map contents", "snippet")
	/* keys! */ //@item(postfixKeys, "keys!", "create slice of keys", "snippet")

	var foo map[int]int
	foo. //@complete(re"() \\/\\/", postfixClear, postfixForMap, postfixForrMap, postfixIfNotNil, postfixKeys, postfixLen, postfixPrint, postfixRangeMap, postfixVar)

	foo = nil

	foo.fo //@snippet(re"() \\/\\/", postfixFor, "for ${1:} := range foo {\n\t$0\n}")
	foo.forr //@snippet(re"() \\/\\/", postfixForr, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
	foo.rang //@snippet(re"() \\/\\/", postfixRange, "for ${1:}, ${2:} := range foo {\n\t$0\n}")
	foo.clear //@snippet(re"() \\/\\/", postfixClear, "for k := range foo {\n\tdelete(foo, k)\n}\n")
	foo.keys //@snippet(re"() \\/\\/", postfixKeys, "keys := make([]int, 0, len(foo))\nfor k := range foo {\n\tkeys = append(keys, k)\n}\n")
}

func _() {
	/* for! */ //@item(postfixForChannel, "for!", "range over channel", "snippet")
	/* range! */ //@item(postfixRangeChannel, "range!", "range over channel", "snippet")

	var foo chan int
	foo. //@complete(re"() \\/\\/", postfixForChannel, postfixIfNotNil, postfixLen, postfixPrint, postfixRangeChannel, postfixVar)

	foo = nil

	foo.fo //@snippet(re"() \\/\\/", postfixForChannel, "for ${1:} := range foo {\n\t$0\n}")
	foo.rang //@snippet(re"() \\/\\/", postfixRangeChannel, "for ${1:} := range foo {\n\t$0\n}")
}

type T struct {
	Name string
}

func _() (string, T, map[string]string, error) {
	/* iferr! */ //@item(postfixIfErr, "iferr!", "check error and return", "snippet")
	/* variferr! */ //@item(postfixVarIfErr, "variferr!", "assign variables and check error", "snippet")
	/* var! */ //@item(postfixVars, "var!", "assign to variables", "snippet")

	strconv.Atoi("32"). //@complete(re"() \\/\\/", postfixIfErr, postfixPrint, postfixVars, postfixVarIfErr)

	var err error
	err.iferr //@snippet(re"() \\/\\/", postfixIfErr, "if err != nil {\n\treturn \"\", T{}, nil, ${1:}\n}\n")

	strconv.Atoi("32").iferr //@snippet(re"() \\/\\/", postfixIfErr, "if _, err := strconv.Atoi(\"32\"); err != nil {\n\treturn \"\", T{}, nil, ${1:}\n}\n")

	strconv.Atoi("32").variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:}, ${2:} := strconv.Atoi(\"32\")\nif ${2:} != nil {\n\treturn \"\", T{}, nil, ${3:}\n}\n")

	// test function return multiple errors
	var foo func() (error, error)
	foo().iferr //@snippet(re"() \\/\\/", postfixIfErr, "if _, err := foo(); err != nil {\n\treturn \"\", T{}, nil, ${1:}\n}\n")
	foo().variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:}, ${2:} := foo()\nif ${2:} != nil {\n\treturn \"\", T{}, nil, ${3:}\n}\n")

	// test function just return error
	var bar func() error
	bar().iferr //@snippet(re"() \\/\\/", postfixIfErr, "if err := bar(); err != nil {\n\treturn \"\", T{}, nil, ${1:}\n}\n")
	bar().variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:} := bar()\nif ${1:} != nil {\n\treturn \"\", T{}, nil, ${2:}\n}\n")
}

func _(){
	/* tostring! */ //@item(postfixToString, "tostring!", "[]byte to string", "snippet")
	var bs []byte
	bs. //@complete(re"() \\/\\/", postfixAppend, postfixCopy, postfixFor, postfixForr, postfixIfNotNil, postfixLast, postfixLen, postfixPrint, postfixRange, postfixReverse, postfixSort, postfixToString, postfixVar)
	bs = nil

	/* tobytes! */ //@item(postfixToBytes, "tobytes!", "string to []byte", "snippet")
	/* split! */ //@item(postfixSplit, "split!", "split string", "snippet")
	var s string
	s. //@complete(re"() \\/\\/", postfixPrint, postfixSplit, postfixToBytes, postfixVar)
	s = ""

	/* tostring! */ //@item(postfixIntToString, "tostring!", "int to string", "snippet")
	var i int
	i. //@complete(re"() \\/\\/", postfixPrint, postfixIntToString, postfixVar)
	i = 0
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/postfix_placeholder.txt
================================================
These tests check that postfix completions  when enable usePlaceholders

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": true
}

-- go.mod --
module golang.org/lsptests/snippets

go 1.18

-- postfix.go --
package snippets

import (
	"strconv"
)

func _() {
	/* for! */ //@item(postfixFor, "for!", "range over slice by index", "snippet")
	/* forr! */ //@item(postfixForr, "forr!", "range over slice by index and value", "snippet")
	/* range! */ //@item(postfixRange, "range!", "range over slice", "snippet")
	/* var! */ //@item(postfixVar, "var!", "assign to variable", "snippet")

	var foo []int

	foo.fo //@snippet(re"() \\/\\/", postfixFor, "for ${1:i} := range foo {\n\t$0\n}")
	foo.forr //@snippet(re"() \\/\\/", postfixForr, "for ${1:i}, ${2:v} := range foo {\n\t$0\n}")
	foo.rang //@snippet(re"() \\/\\/", postfixRange, "for ${1:i}, ${2:v} := range foo {\n\t$0\n}")
	foo.va //@snippet(re"() \\/\\/", postfixVar, "${1:i} := foo")
}

func _() {
	/* for! */ //@item(postfixForMap, "for!", "range over map by key", "snippet")
	/* forr! */ //@item(postfixForrMap, "forr!", "range over map by key and value", "snippet")
	/* range! */ //@item(postfixRangeMap, "range!", "range over map", "snippet")

	var foo map[int]int

	foo.fo //@snippet(re"() \\/\\/", postfixFor, "for ${1:k} := range foo {\n\t$0\n}")
	foo.forr //@snippet(re"() \\/\\/", postfixForr, "for ${1:k}, ${2:v} := range foo {\n\t$0\n}")
	foo.rang //@snippet(re"() \\/\\/", postfixRange, "for ${1:k}, ${2:v} := range foo {\n\t$0\n}")
}

func _() {
	/* for! */ //@item(postfixForChannel, "for!", "range over channel", "snippet")
	/* range! */ //@item(postfixRangeChannel, "range!", "range over channel", "snippet")

	var foo chan int

	foo.fo //@snippet(re"() \\/\\/", postfixForChannel, "for ${1:e} := range foo {\n\t$0\n}")
	foo.rang //@snippet(re"() \\/\\/", postfixRangeChannel, "for ${1:e} := range foo {\n\t$0\n}")
}

type T struct {
	Name string
}

func _() (string, T, map[string]string, error) {
	/* iferr! */ //@item(postfixIfErr, "iferr!", "check error and return", "snippet")
	/* variferr! */ //@item(postfixVarIfErr, "variferr!", "assign variables and check error", "snippet")
	/* var! */ //@item(postfixVars, "var!", "assign to variables", "snippet")


	var err error
	err.iferr //@snippet(re"() \\/\\/", postfixIfErr, "if err != nil {\n\treturn \"\", T{}, nil, ${1:err}\n}\n")
	strconv.Atoi("32").iferr //@snippet(re"() \\/\\/", postfixIfErr, "if _, err := strconv.Atoi(\"32\"); err != nil {\n\treturn \"\", T{}, nil, ${1:err}\n}\n")
	strconv.Atoi("32").variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:i}, ${2:err} := strconv.Atoi(\"32\")\nif ${2:err} != nil {\n\treturn \"\", T{}, nil, ${3:${2:err}}\n}\n")

	// test function return multiple errors
	var foo func() (error, error)
	foo().iferr //@snippet(re"() \\/\\/", postfixIfErr, "if _, err := foo(); err != nil {\n\treturn \"\", T{}, nil, ${1:err}\n}\n")
	foo().variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:err2}, ${2:err} := foo()\nif ${2:err} != nil {\n\treturn \"\", T{}, nil, ${3:${2:err}}\n}\n")

	// test function just return error
	var bar func() error
	bar().iferr //@snippet(re"() \\/\\/", postfixIfErr, "if err := bar(); err != nil {\n\treturn \"\", T{}, nil, ${1:err}\n}\n")
	bar().variferr //@snippet(re"() \\/\\/", postfixVarIfErr, "${1:err2} := bar()\nif ${1:err2} != nil {\n\treturn \"\", T{}, nil, ${2:${1:err2}}\n}\n")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/printf.txt
================================================
This test checks various ranking of completion results related to printf.

-- flags --
-ignore_extra_diags

-- printf.go --
package printf

import "fmt"

func myPrintf(string, ...any) {}

func _() {
	var (
		aInt      int          //@item(printfInt, "aInt", "int", "var")
		aFloat    float64      //@item(printfFloat, "aFloat", "float64", "var")
		aString   string       //@item(printfString, "aString", "string", "var")
		aBytes    []byte       //@item(printfBytes, "aBytes", "[]byte", "var")
		aStringer fmt.Stringer //@item(printfStringer, "aStringer", "fmt.Stringer", "var")
		aError    error        //@item(printfError, "aError", "error", "var")
		aBool     bool         //@item(printfBool, "aBool", "bool", "var")
	)

	myPrintf("%d", a)       //@rank(re"()\\)", printfInt, printfFloat)
	myPrintf("%s", a)       //@rank(re"()\\)", printfString, printfInt),rank(re"()\\)", printfBytes, printfInt),rank(re"()\\)", printfStringer, printfInt),rank(re"()\\)", printfError, printfInt)
	myPrintf("%w", a)       //@rank(re"()\\)", printfError, printfInt)
	myPrintf("%x %[1]b", a) //@rank(re"()\\)", printfInt, printfString)

	fmt.Printf("%t", a) //@rank(re"()\\)", printfBool, printfInt)

	fmt.Fprintf(nil, "%f", a) //@rank(re"()\\)", printfFloat, printfInt)

	fmt.Sprintf("%[2]q %[1]*.[3]*[4]f",
		a, //@rank(re"(),", printfInt, printfFloat)
		a, //@rank(re"(),", printfString, printfFloat)
		a, //@rank(re"(),", printfInt, printfFloat)
		a, //@rank(re"(),", printfFloat, printfInt)
	)

  // Don't insert as "&aStringer"
	fmt.Printf("%p", a) //@snippet(re"()\\)", printfStringer, "aStringer")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/randv2.txt
================================================
Unimported completions has to find math/rand/v2
-- flags --
-min_go_command=go1.22

-- settings.json --
{
	"importsSource": "gopls"
}

-- go.mod --
module unimported.test

go 1.22

-- main.go --
package main
var _ = rand.Int64 //@complete(re"()Int64", Int64, Int64N, x64, Uint64, Uint64N), diag("rand", re"undefined: rand")
// ordering of these requires completion order be deterministic
// for now, we do not know the types. Awaiting CL 665335
//@item(Int64, "Int64", "func (from \"math/rand/v2\")", "func")
//@item(Int64N, "Int64N", "func (from \"math/rand/v2\")", "func")
//@item(x64, "Uint64", "func (from \"math/rand\")", "func")
//@item(Uint64, "Uint64", "func (from \"math/rand/v2\")", "func")
//@item(Uint64N, "Uint64N", "func (from \"math/rand/v2\")", "func")


================================================
FILE: gopls/internal/test/marker/testdata/completion/range_func.txt
================================================
This test shows we prefer rangeable funcs in range statements.

-- flags --
-ignore_extra_diags

-- range_func.go --
package rangefunc

func iterNot(func(int)) {}
func iter0(func() bool) {}
func iter1(func(int) bool) {}
func iter2(func(int, int) bool)

func _() {
	for range i { //@rank(re"() {", "iter0", "iterNot"),rank(re"() {", "iter1", "iterNot"),rank(re"() {", "iter2", "iterNot")
	}

	for k := range i { //@rank(re"() {", "iter1", "iterNot"),rank(re"() {", "iter1", "iter0"),rank(re"() {", "iter2", "iter0")
	}

	for k, v := range i { //@rank(re"() {", "iter2", "iterNot"),rank(re"() {", "iter2", "iter0"),rank(re"() {", "iter2", "iter1")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/rank.txt
================================================
This test checks various ranking of completion results.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false,
	"deepCompletion": false
}

-- go.mod --
module golang.org/lsptests/rank

go 1.18

-- struct/struct_rank.go --
package struct_rank

type foo struct {
	c int //@item(c_rank, "c", "int", "field")
	b int //@item(b_rank, "b", "int", "field")
	a int //@item(a_rank, "a", "int", "field")
}

func f() {
	foo := foo{} //@rank(re"()}", c_rank, b_rank, a_rank)
}

-- assign_rank.go --
package rank

// Literal completion results.
/* int() */ //@item(int, "int()", "int", "var")
/* string() */ //@item(string, "string()", "string", "var")

var (
	apple int = 3         //@item(apple, "apple", "int", "var")
	pear string = "hello" //@item(pear, "pear", "string", "var")
)

func _() {
	orange := 1      //@item(orange, "orange", "int", "var")
	grape := "hello" //@item(grape, "grape", "string", "var")
	orange, grape = 2, "hello"  //@complete(re"() \"", grape, pear, string, orange, apple)
}

func _() {
	var pineapple int //@item(pineapple, "pineapple", "int", "var")
	pineapple = 1    //@complete(re"() 1", pineapple, apple, int, pear)

	y := //@complete(re"() \\/", pineapple, apple, pear)
}

-- binexpr_rank.go --
package rank

func _() {
  _ = 5 +  ; //@complete(re"() ;", apple, pear)
  y :=  + 5; //@complete(re"() +", apple, pear)

  if 6 ==  {} //@complete(re"() {", apple, pear)
}

-- boolexpr_rank.go --
package rank

func _() {
	someRandomBoolFunc := func() bool { //@item(boolExprFunc, "someRandomBoolFunc", "func() bool", "var")
		return true
	}

	var foo, bar int     //@item(boolExprBar, "bar", "int", "var")
	if foo == 123 && b { //@rank(re"() {", boolExprBar, boolExprFunc)
	}
}

-- convert_rank.go --
package rank

import "time"

// Copied from the old builtins.go, which has been ported to the new marker tests.
/* complex(r float64, i float64) */ //@item(complex, "complex", "func(r float64, i float64) complex128", "func")

func _() {
	type strList []string
	wantsStrList := func(strList) {}

	var (
		convA string   //@item(convertA, "convA", "string", "var")
		convB []string //@item(convertB, "convB", "[]string", "var")
	)
	wantsStrList(strList(conv)) //@complete(re"()\\)\\)", convertB, convertA)
}

func _() {
	type myInt int

	const (
		convC        = "hi"    //@item(convertC, "convC", "string", "const")
		convD        = 123     //@item(convertD, "convD", "int", "const")
		convE int    = 123     //@item(convertE, "convE", "int", "const")
		convF string = "there" //@item(convertF, "convF", "string", "const")
		convG myInt  = 123     //@item(convertG, "convG", "myInt", "const")
	)

	var foo int
	foo = conv //@rank(re"() \\/\\/", convertE, convertD)

	var mi myInt
	mi = conv //@rank(re"() \\/\\/", convertG, convertD, convertE)
	mi + conv //@rank(re"() \\/\\/", convertG, convertD, convertE)

	1 + conv //@rank(re"() \\/\\/", convertD, convertC),rank(re"() \\/\\/", convertE, convertC),rank(re"() \\/\\/", convertG, convertC)

	type myString string
	var ms myString
	ms = conv //@rank(re"() \\/\\/", convertC, convertF)

	type myUint uint32
	var mu myUint
	mu = conv //@rank(re"() \\/\\/", convertD, convertE)

	// don't downrank constants when assigning to any
	var _ any = c //@rank(re"() \\/\\/", convertD, complex)

	var _ time.Duration = conv //@rank(re"() \\/\\/", convertD, convertE),snippet(re"() \\/\\/", convertE, "time.Duration(convE)")

	var convP myInt   //@item(convertP, "convP", "myInt", "var")
	var _ *int = conv //@snippet(re"() \\/\\/", convertP, "(*int)(&convP)")

	var ff float64 //@item(convertFloat, "ff", "float64", "var")
	f == convD     //@snippet(re"() =", convertFloat, "ff")
}

-- switch_rank.go --
package rank

import "time"

func _() {
	switch pear {
	case _: //@rank(re"()_", pear, apple)
	}

	time.Monday //@item(timeMonday, "time.Monday", "time.Weekday", "const"),item(monday ,"Monday", "time.Weekday", "const")
	time.Friday //@item(timeFriday, "time.Friday", "time.Weekday", "const"),item(friday ,"Friday", "time.Weekday", "const")

	now := time.Now()
	now.Weekday //@item(nowWeekday, "now.Weekday", "func() time.Weekday", "method")

	then := time.Now()
	then.Weekday //@item(thenWeekday, "then.Weekday", "func() time.Weekday", "method")

	switch time.Weekday(0) {
	case time.Monday, time.Tuesday:
	case time.Wednesday, time.Thursday:
	case time.Saturday, time.Sunday:
	// TODO: these tests were disabled because they require deep completion
	// (which would break other tests)
	case t: // rank(re"():", timeFriday, timeMonday)
	case time.: //@rank(re"():", friday, monday)

	case now.Weekday():
	case week: // rank(re"():", thenWeekday, nowWeekday)
	}
}

-- type_assert_rank.go --
package rank

func _() {
	type flower int //@item(flower, "flower", "int", "type")
	var fig string  //@item(fig, "fig", "string", "var")

	_ = interface{}(nil).(f) //@complete(re"()\\) \\/\\/", flower)
}

-- type_switch_rank.go --
package rank

import (
	"fmt"
	"go/ast"
)

func _() {
	type basket int   //@item(basket, "basket", "int", "type")
	var banana string //@item(banana, "banana", "string", "var")

	switch interface{}(pear).(type) {
	case b: //@complete(re"():", basket)
		b //@complete(re"() \\/\\/", banana, basket)
	}

	Ident  //@item(astIdent, "Ident", "struct{...}", "struct")
	IfStmt //@item(astIfStmt, "IfStmt", "struct{...}", "struct")

	switch ast.Node(nil).(type) {
	case *ast.Ident:
	case *ast.I: //@rank(re"():", astIfStmt, astIdent)
	}

	Stringer   //@item(fmtStringer, "Stringer", "interface{...}", "interface")
	GoStringer //@item(fmtGoStringer, "GoStringer", "interface{...}", "interface")

	switch interface{}(nil).(type) {
	case fmt.Stringer: //@rank(re"():", fmtStringer, fmtGoStringer)
	}
}



================================================
FILE: gopls/internal/test/marker/testdata/completion/snippet.txt
================================================
This test checks basic completion snippet support.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/snippet

-- snippet.go --
package snippets

// Pre-set this marker, as we don't have a "source" for it in this package.
// The comment is used to create a synthetic completion item.
//
// TODO(rfindley): allow completion markers to refer to ad-hoc items inline,
// without this trick.
/* Error() */ //@item(Error, "Error", "func() string", "method")

type AliasType = int //@item(sigAliasType, "AliasType", "AliasType", "type")

func foo(i int, b bool) {} //@item(snipFoo, "foo", "func(i int, b bool)", "func")
func bar(fn func()) func()    {} //@item(snipBar, "bar", "func(fn func())", "func")
func baz(at AliasType, b bool) {} //@item(snipBaz, "baz", "func(at AliasType, b bool)", "func")

type Foo struct {
	Bar int //@item(snipFieldBar, "Bar", "int", "field")
	Func func(at AliasType) error //@item(snipFieldFunc, "Func", "func(at AliasType) error", "field")
}

func (Foo) Baz() func() {} //@item(snipMethodBaz, "Baz", "func() func()", "method")
func (Foo) BazBar() func() {} //@item(snipMethodBazBar, "BazBar", "func() func()", "method")
func (Foo) BazBaz(at AliasType) func() {} //@item(snipMethodBazBaz, "BazBaz", "func(at AliasType) func()", "method")

func _() {
	f //@snippet(re"() \\/\\/", snipFoo, "foo(${1:})")

	bar //@snippet(re"() \\/\\/", snipBar, "bar(${1:})")

	baz() //@snippet(re"()\\(", snipBaz, "baz")

	bar(nil) //@snippet(re"()\\(", snipBar, "bar")
	bar(ba) //@snippet(re"()\\)", snipBar, "bar(${1:})")
	var f Foo
	bar(f.Ba) //@snippet(re"()\\)", snipMethodBaz, "Baz()")
	(bar)(nil) //@snippet(re"()\\)", snipBar, "bar(${1:})")
	(f.Ba)() //@snippet(re"()\\)", snipMethodBaz, "Baz()")

	Foo{
		B //@snippet(re"() \\/\\/", snipFieldBar, "Bar: ${1:},")
	}

	Foo{
		F //@snippet(re"() \\/\\/", snipFieldFunc, "Func: ${1:},")
	}

	Foo{B} //@snippet(re"()}", snipFieldBar, "Bar: ${1:}")
	Foo{} //@snippet(re"()}", snipFieldBar, "Bar: ${1:}")

	Foo{Foo{}.B} //@snippet(re"()} ", snipFieldBar, "Bar")

	var err error
	err.Error() //@snippet(re"()E", Error, "Error()")
	f.Baz()     //@snippet(re"()B", snipMethodBaz, "Baz()")

	f.Baz()     //@snippet(re"()\\(", snipMethodBazBar, "BazBar")

	f.Baz()     //@snippet(re"()B", snipMethodBazBaz, "BazBaz(${1:})")
}

func _() {
	type bar struct {
		a int
		b float64 //@item(snipBarB, "b", "float64")
	}
	bar{b} //@snippet(re"()}", snipBarB, "b: ${1:}")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/snippet_placeholder.txt
================================================
This test checks basic completion snippet support, using placeholders.

Unlike the old marker tests, the new marker tests assume static configuration
(as defined by settings.json), and therefore there is duplication between this
test and snippet.txt. This is a price we pay so that we don't have to mutate
the server during testing.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": true
}

-- go.mod --
module golang.org/lsptests/snippet

-- snippet.go --
package snippets

// Pre-set this marker, as we don't have a "source" for it in this package.
/* Error() */ //@item(Error, "Error", "func() string", "method")

type AliasType = int //@item(sigAliasType, "AliasType", "AliasType", "type")

func foo(i int, b bool) {} //@item(snipFoo, "foo", "func(i int, b bool)", "func")
func bar(fn func()) func()    {} //@item(snipBar, "bar", "func(fn func())", "func")
func baz(at AliasType, b bool) {} //@item(snipBaz, "baz", "func(at AliasType, b bool)", "func")

type Foo struct {
	Bar int //@item(snipFieldBar, "Bar", "int", "field")
	Func func(at AliasType) error //@item(snipFieldFunc, "Func", "func(at AliasType) error", "field")
}

func (Foo) Baz() func() {} //@item(snipMethodBaz, "Baz", "func() func()", "method")
func (Foo) BazBar() func() {} //@item(snipMethodBazBar, "BazBar", "func() func()", "method")
func (Foo) BazBaz(at AliasType) func() {} //@item(snipMethodBazBaz, "BazBaz", "func(at AliasType) func()", "method")

func _() {
	f //@snippet(re"() \\/\\/", snipFoo, "foo(${1:i int}, ${2:b bool})")

	bar //@snippet(re"() \\/\\/", snipBar, "bar(${1:fn func()})")

	baz //@snippet(re"() \\/\\/", snipBaz, "baz(${1:at AliasType}, ${2:b bool})")

	bar(nil) //@snippet(re"()\\(", snipBar, "bar")
	bar(ba) //@snippet(re"()\\)", snipBar, "bar(${1:fn func()})")
	var f Foo
	bar(f.Ba) //@snippet(re"()\\)", snipMethodBaz, "Baz()")
	(bar)(nil) //@snippet(re"()\\)", snipBar, "bar(${1:fn func()})")
	(f.Ba)() //@snippet(re"()\\)", snipMethodBaz, "Baz()")

	Foo{
		B //@snippet(re"() \\/\\/", snipFieldBar, "Bar: ${1:int},")
	}

	Foo{
		F //@snippet(re"() \\/\\/", snipFieldFunc, "Func: ${1:func(at AliasType) error},")
	}

	Foo{B} //@snippet(re"()}", snipFieldBar, "Bar: ${1:int}")
	Foo{} //@snippet(re"()}", snipFieldBar, "Bar: ${1:int}")

	Foo{Foo{}.B} //@snippet(re"()} ", snipFieldBar, "Bar")

	var err error
	err.Error() //@snippet(re"()E", Error, "Error()")
	f.Baz()     //@snippet(re"()B", snipMethodBaz, "Baz()")

	f.Baz()     //@snippet(re"()\\(", snipMethodBazBar, "BazBar")

	f.Baz()     //@snippet(re"()B", snipMethodBazBaz, "BazBaz(${1:at AliasType})")
}

func _() {
	type bar struct {
		a int
		b float64 //@item(snipBarB, "b", "field")
	}
	bar{b} //@snippet(re"()}", snipBarB, "b: ${1:float64}")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/statements.txt
================================================
This test exercises completion around various statements.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"usePlaceholders": true
}

-- go.mod --
module golang.org/lsptests/statements

-- append.go --
package statements

func _() {
	type mySlice []int

	var (
		abc    []int   //@item(stmtABC, "abc", "[]int", "var")
		abcdef mySlice //@item(stmtABCDEF, "abcdef", "mySlice", "var")
	)

	/* abcdef = append(abcdef, ) */ //@item(stmtABCDEFAssignAppend, "abcdef = append(abcdef, )", "", "func")

	// don't offer "abc = append(abc, )" because "abc" isn't necessarily
	// better than "abcdef".
	abc //@complete(re"() \\/\\/", stmtABC, stmtABCDEF)

	abcdef //@complete(re"() \\/\\/", stmtABCDEF, stmtABCDEFAssignAppend)

	/* append(abc, ) */ //@item(stmtABCAppend, "append(abc, )", "", "func")

	abc = app //@snippet(re"() \\/\\/", stmtABCAppend, "append(abc, ${1:})")
}

func _() {
	var s struct{ xyz []int }

	/* xyz = append(s.xyz, ) */ //@item(stmtXYZAppend, "xyz = append(s.xyz, )", "", "func")

	s.x //@snippet(re"() \\/\\/", stmtXYZAppend, "xyz = append(s.xyz, ${1:})")

	/* s.xyz = append(s.xyz, ) */ //@item(stmtDeepXYZAppend, "s.xyz = append(s.xyz, )", "", "func")

	sx //@snippet(re"() \\/\\/", stmtDeepXYZAppend, "s.xyz = append(s.xyz, ${1:})")
}

func _() {
	var foo [][]int

	/* append(foo[0], ) */ //@item(stmtFooAppend, "append(foo[0], )", "", "func")

	foo[0] = app //@complete(re"() \\/\\/", stmtFooAppend),snippet(re"() \\/\\/", stmtFooAppend, "append(foo[0], ${1:})")
}

-- if_err_check_return.go --
package statements

import (
	"bytes"
	"io"
	"os"
)

func one() (int, float32, io.Writer, *int, []int, bytes.Buffer, error) {
	/* if err != nil { return err } */ //@item(stmtOneIfErrReturn, "if err != nil { return err }", "", "")
	/* err != nil { return err } */ //@item(stmtOneErrReturn, "err != nil { return err }", "", "")

	_, err := os.Open("foo")
	//@snippet("", stmtOneIfErrReturn, "if err != nil {\n\treturn 0, 0, nil, nil, nil, bytes.Buffer{\\}, ${1:err}\n\\}")

	_, err = os.Open("foo")
	i //@snippet(re"() \\/\\/", stmtOneIfErrReturn, "if err != nil {\n\treturn 0, 0, nil, nil, nil, bytes.Buffer{\\}, ${1:err}\n\\}")

	_, err = os.Open("foo")
	if er //@snippet(re"() \\/\\/", stmtOneErrReturn, "err != nil {\n\treturn 0, 0, nil, nil, nil, bytes.Buffer{\\}, ${1:err}\n\\}")

	_, err = os.Open("foo")
	if //@snippet(re"() \\/\\/", stmtOneIfErrReturn, "if err != nil {\n\treturn 0, 0, nil, nil, nil, bytes.Buffer{\\}, ${1:err}\n\\}")

	_, err = os.Open("foo")
	if //@snippet(re"()\\/\\/", stmtOneIfErrReturn, "if err != nil {\n\treturn 0, 0, nil, nil, nil, bytes.Buffer{\\}, ${1:err}\n\\}")
}

-- if_err_check_return2.go --
package statements

import "os"

func two() error {
	var s struct{ err error }

	/* if s.err != nil { return s.err } */ //@item(stmtTwoIfErrReturn, "if s.err != nil { return s.err }", "", "")

	_, s.err = os.Open("foo")
	//@snippet("", stmtTwoIfErrReturn, "if s.err != nil {\n\treturn ${1:s.err}\n\\}")
}

-- if_err_check_return3.go --
package statements

import "os"

// Check that completion logic handles an invalid return type.
func badReturn() (NotAType, error) {
	_, err := os.Open("foo")
	//@snippet("", stmtOneIfErrReturn, "if err != nil {\n\treturn , ${1:err}\n\\}")

	_, err = os.Open("foo")
	if er //@snippet(re"() \\/\\/", stmtOneErrReturn, "err != nil {\n\treturn , ${1:err}\n\\}")
}

-- if_err_check_test.go --
package statements

import (
	"os"
	"testing"
)

func TestErr(t *testing.T) {
	/* if err != nil { t.Fatal(err) } */ //@item(stmtOneIfErrTFatal, "if err != nil { t.Fatal(err) }", "", "")

	_, err := os.Open("foo")
	//@snippet("", stmtOneIfErrTFatal, "if err != nil {\n\tt.Fatal(err)\n\\}")
}

func BenchmarkErr(b *testing.B) {
	/* if err != nil { b.Fatal(err) } */ //@item(stmtOneIfErrBFatal, "if err != nil { b.Fatal(err) }", "", "")

	_, err := os.Open("foo")
	//@snippet("", stmtOneIfErrBFatal, "if err != nil {\n\tb.Fatal(err)\n\\}")
}

-- return.go --
package statements

//@item(stmtReturnZeroValues, `return 0, "", nil`)

func foo() (int, string, error) {
	ret //@snippet(re"() ", stmtReturnZeroValues, "return ${1:0}, ${2:\"\"}, ${3:nil}")
}

func bar() (int, string, error) {
	return //@snippet(re"() ", stmtReturnZeroValues, "return ${1:0}, ${2:\"\"}, ${3:nil}")
}


//@item(stmtReturnInvalidValues, `return `)

func invalidReturnStatement() NotAType {
	return //@snippet(re"() ", stmtReturnInvalidValues, "return ${1:}")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/testy.txt
================================================

-- flags --
-ignore_extra_diags

-- go.mod --
module testy.test

go 1.18

-- types/types.go --
package types


-- signature/signature.go --
package signature

type Alias = int

-- snippets/snippets.go --
package snippets

import (
	"testy.test/signature"
	t "testy.test/types"
)

func X(_ map[signature.Alias]t.CoolAlias) (map[signature.Alias]t.CoolAlias) {
	return nil
}

-- testy/testy.go --
package testy

func a() { //@item(funcA, "a", "func()", "func")
	//@complete("", funcA)
}


-- testy/testy_test.go --
package testy

import (
	"testing"

	sig "testy.test/signature"
	"testy.test/snippets"
)

func TestSomething(t *testing.T) { //@item(TestSomething, "TestSomething(t *testing.T)", "", "func")
	var x int //@loc(testyX, "x"), diag("x", re"declared (and|but) not used")
	a()       //@loc(testyA, "a")
}

func _() {
	_ = snippets.X(nil) //@signature("nil", "X(_ map[sig.Alias]types.CoolAlias) map[sig.Alias]types.CoolAlias", 0)
	var _ sig.Alias
}

func issue63578(err error) {
	err.Error() //@signature(re"()\\)", "Error() string", -1)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/type_assert.txt
================================================
This test checks completion related to type assertions.

-- flags --
-ignore_extra_diags

-- type_assert.go --
package typeassert

type abc interface { //@item(abcIntf, "abc", "interface{...}", "interface")
	abc()
}

type abcImpl struct{} //@item(abcImpl, "abcImpl", "struct{...}", "struct")
func (abcImpl) abc()

type abcPtrImpl struct{} //@item(abcPtrImpl, "abcPtrImpl", "struct{...}", "struct")
func (*abcPtrImpl) abc()

type abcNotImpl struct{} //@item(abcNotImpl, "abcNotImpl", "struct{...}", "struct")

func _() {
	var a abc
	switch a.(type) {
	case ab: //@complete(re"():", abcImpl, abcPtrImpl, abcIntf, abcNotImpl)
	case *ab: //@complete(re"():", abcImpl, abcPtrImpl, abcIntf, abcNotImpl)
	}

	a.(ab)  //@complete(re"()\\)", abcImpl, abcPtrImpl, abcIntf, abcNotImpl)
	a.(*ab) //@complete(re"()\\)", abcImpl, abcPtrImpl, abcIntf, abcNotImpl)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/type_mods.txt
================================================
This test check completion snippets with type modifiers.

-- flags --
-ignore_extra_diags

-- typemods.go --
package typemods

func fooFunc() func() int {
	return func() int {
		return 0
	}
}

func fooPtr() *int {
	return nil
}

func _() {
	var _ int = foo //@snippet(re"() \\/\\/", "fooFunc", "fooFunc()()"),snippet(re"() \\/\\/", "fooPtr", "*fooPtr()")
}

func _() {
	var m map[int][]chan int

	var _ int = m //@snippet(re"() \\/\\/", "m", "<-m[${1:}][${2:}]")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/type_params.txt
================================================
This test checks various ranking of completion results related to type
parameters.

-- flags --
-ignore_extra_diags

-- type_params.go --
package typeparams

// Copied from the old builtins.go, which has been ported to the new marker tests.
/* string */ //@item(string, "string", "", "type")
/* float32 */ //@item(float32, "float32", "", "type")
/* float64 */ //@item(float64, "float64", "", "type")
/* int */ //@item(int, "int", "", "type")

func one[a int | string]()            {}
func two[a int | string, b float64 | int]() {}
type three[a any] int

func _() {
	one[]() //@rank(re"()]", string, float64)
	two[]() //@rank(re"()]", int, float64)
	two[int, f]() //@rank(re"()]", float64, float32)
	int(three[]) //@rank(re"()]") // must not crash (golang/go#70889)
}

func slices[a []int | []float64]() {} //@item(tpInts, "[]int", "[]int", "type"),item(tpFloats, "[]float64", "[]float64", "type")

func _() {
	slices[]() //@rank(re"()]", tpInts),rank(re"()]", tpFloats)
}

type s[a int | string] struct{}

func _() {
	s[]{} //@rank(re"()]", int, float64)
}

func takesGeneric[a int | string](s[a]) {
	"s[a]{}" //@item(tpInScopeLit, "s[a]{}", "", "var")
	takesGeneric() //@rank(re"()\\)", tpInScopeLit),snippet(re"()\\)", tpInScopeLit, "s[a]{\\}")
}

func _() {
	s[int]{} //@item(tpInstLit, "s[int]{}", "", "var")
	takesGeneric[int]() //@rank(re"()\\)", tpInstLit),snippet(re"()\\)", tpInstLit, "s[int]{\\}")

	"s[...]{}" //@item(tpUninstLit, "s[...]{}", "", "var")
	takesGeneric() //@rank(re"()\\)", tpUninstLit),snippet(re"()\\)", tpUninstLit, "s[${1:}]{\\}")
}

func returnTP[A int | float64](a A) A { //@item(returnTP, "returnTP", "something", "func")
	return a
}

func _() {
	var _ int = returnTP //@snippet(re"() \\/\\/", returnTP, "returnTP(${1:})")

	var aa int //@item(tpInt, "aa", "int", "var")
	var ab float64 //@item(tpFloat, "ab", "float64", "var")
	returnTP[int](a) //@rank(re"()\\)", tpInt, tpFloat)
}

func takesFunc[T any](func(T) T) {
	var _ func(t T) T = f //@snippet(re"() \\/\\/", tpLitFunc, "func(t T) T {$0\\}")
}

func _() {
	_ = "func(...) {}" //@item(tpLitFunc, "func(...) {}", "", "var")
	takesFunc() //@snippet(re"()\\)", tpLitFunc, "func(${1:}) ${2:} {$0\\}")
	takesFunc[int]() //@snippet(re"()\\)", tpLitFunc, "func(i int) int {$0\\}")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/type_params_reverse_infer.txt
================================================
-- flags --
-ignore_extra_diags

-- declarations.go --
package x

import (
	"cmp"
	"io"
	"os"
)

var File *os.File

func A[T cmp.Ordered](T) int { return 0 }

func B[T comparable](T) int { return 0 }

func C[T int | string](T) int { return 0 }

func D[T io.Reader](T) int { return 0 }

-- a.go --
package x

func _(i int) {
	i = A(File.Nam) //@acceptcompletion(re"Nam()", "Name", A)
}

-- @A/a.go --
package x

func _(i int) {
	i = A(File.Name()) //@acceptcompletion(re"Nam()", "Name", A)
}

-- b.go --
package x

func _(i int) {
	i = B(File.Nam) //@acceptcompletion(re"Nam()", "Name", B)
}

-- @B/b.go --
package x

func _(i int) {
	i = B(File.Name()) //@acceptcompletion(re"Nam()", "Name", B)
}

-- c.go --
package x

func _(i int) {
	i = C(File.Nam) //@acceptcompletion(re"Nam()", "Name", C)
}

-- @C/c.go --
package x

func _(i int) {
	i = C(File.Name()) //@acceptcompletion(re"Nam()", "Name", C)
}

-- d.go --
package x

func _(i int) {
	i = D(Fil) //@acceptcompletion(re"Fil()", "File", D)
}

-- @D/d.go --
package x

func _(i int) {
	i = D(File) //@acceptcompletion(re"Fil()", "File", D)
}



================================================
FILE: gopls/internal/test/marker/testdata/completion/unimported-std.txt
================================================
Test of unimported completions respecting the effective Go version of the file.

(See unprefixed file for same test of imported completions.)

These symbols below were introduced to go/types in go1.22:

  Alias
  Info.FileVersions
  (Checker).PkgNameOf

The underlying logic depends on versions.FileVersion, which only
behaves correctly in go1.22. (When go1.22 is assured, we can remove
the min_go flag but leave the test inputs unchanged.)

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

// package-level func
var _ = types.Sat //@rank(re"()Sat", "Satisfies")
var _ = types.Ali //@rank(re"()Ali", "!Alias")

// (We don't offer completions of methods
// of types from unimported packages, so the fact that
// we don't implement std version filtering isn't evident.)

// field
var _ = new(types.Info).Use //@rank(re"()Use", "!Uses")
var _ = new(types.Info).Fil //@rank(re"()Fil", "!FileVersions")

// method
var _ = new(types.Checker).Obje //@rank(re"()Obje", "!ObjectOf")
var _ = new(types.Checker).PkgN //@rank(re"()PkgN", "!PkgNameOf")

-- b/b.go --
//go:build go1.22

package a

// package-level decl
var _ = types.Sat //@rank(re"()Sat", "Satisfies")
var _ = types.Ali //@rank(re"()Ali", "Alias")


================================================
FILE: gopls/internal/test/marker/testdata/completion/unimported.txt
================================================

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"importsSource": "gopls"
}

-- go.mod --
module unimported.test

go 1.18

-- unimported/export_test.go --
package unimported

var TestExport int //@item(testexport, "TestExport", "var (from \"unimported.test/unimported\")", "var")

-- signature/signature.go --
package signature

func Foo() {}

-- foo/foo.go --
package foo

type StructFoo struct{ F int }

-- baz/baz.go --
package baz

import (
	f "unimported.test/foo"
)

var FooStruct f.StructFoo

-- unimported/unimported.go --
package unimported

func _() {
	http //@complete(re"()p", http, httptest, httptrace, httputil)
	// container/ring is extremely unlikely to be imported by anything, so shouldn't have type information.
	ring.Ring     //@complete(re"R()ing", ringring)
	signature.Foo //@complete(re"()Foo", signaturefoo)

	context.Bac //@complete(re"() \\/\\/", contextBackground)
}

// Create markers for unimported std lib packages. Only for use by this test.
/* http */ //@item(http, "http", "\"net/http\"", "package")
/* httptest */ //@item(httptest, "httptest", "\"net/http/httptest\"", "package")
/* httptrace */ //@item(httptrace, "httptrace", "\"net/http/httptrace\"", "package")
/* httputil */ //@item(httputil, "httputil", "\"net/http/httputil\"", "package")

/* ring.Ring */ //@item(ringring, "Ring", "type (from \"container/ring\")", "var")

/* signature.Foo */ //@item(signaturefoo, "Foo", "func (from \"unimported.test/signature\")", "func")

/* context.Background */ //@item(contextBackground, "Background", "func (from \"context\")", "func")

// Now that we no longer type-check imported completions,
// we don't expect the context.Background().Err method (see golang/go#58663).
/* context.Background().Err */ //@item(contextBackgroundErr, "Background().Err", "func (from \"context\")", "method")

-- unimported/unimported_cand_type.go --
package unimported

import (
	_ "context"

	"unimported.test/baz"
)

func _() {
	foo.StructFoo{} //@item(litFooStructFoo, "foo.StructFoo{}", "struct{...}", "struct")

	// We get the literal completion for "foo.StructFoo{}" even though we haven't
	// imported "foo" yet.
	baz.FooStruct = f //@snippet(re"() \\/\\/", litFooStructFoo, "foo.StructFoo{$0\\}")
}

-- unimported/x_test.go --
package unimported_test

import (
	"testing"
)

func TestSomething(t *testing.T) {
	_ = unimported.TestExport //@complete(re"()TestExport", testexport)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/unresolved.txt
================================================
This test verifies gopls does not crash on fake "resolved" types.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"completeUnimported": false
}

-- unresolved.go --
package unresolved

func foo(any) {
	foo(func(i, j f //@complete(re"() \\/\\/")
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/unsafe.txt
================================================
This test checks completion of symbols in the 'unsafe' package.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"matcher": "caseinsensitive"
}

-- unsafe.go --
package unsafe

import (
	"unsafe"
)

// Pre-set this marker, as we don't have a "source" for it in this package.
/* unsafe.Sizeof */ //@item(Sizeof, "Sizeof", "invalid type", "text")

func _() {
	x := struct{}{}
	_ = unsafe.Sizeof(x) //@complete(re"()z", Sizeof)
}


================================================
FILE: gopls/internal/test/marker/testdata/completion/variadic.txt
================================================
This test checks completion related to variadic functions.

-- flags --
-ignore_extra_diags

-- variadic.go --
package variadic

func foo(i int, strs ...string) {}

func bar() []string { //@item(vFunc, "bar", "func() []string", "func")
	return nil
}

func _() {
	var (
		i  int        //@item(vInt, "i", "int", "var")
		s  string     //@item(vStr, "s", "string", "var")
		ss []string   //@item(vStrSlice, "ss", "[]string", "var")
		v any //@item(vIntf, "v", "any", "var")
	)

	foo()           //@rank(re"()\\)", vInt, vStr),rank(re"()\\)", vInt, vStrSlice)
	foo(123, )      //@rank(re"()\\)", vStr, vInt),rank(re"()\\)", vStrSlice, vInt)
	foo(123, "", )  //@rank(re"()\\)", vStr, vInt),rank(re"()\\)", vStr, vStrSlice)
	foo(123, s, "") //@rank(re"(), \"", vStr, vStrSlice)

  // snippet will add the "..." for you
	foo(123, ) //@snippet(re"()\\)", vStrSlice, "ss..."),snippet(re"()\\)", vFunc, "bar()..."),snippet(re"()\\)", vStr, "s")

	// don't add "..." for any
	foo(123, ) //@snippet(re"()\\)", vIntf, "v")
}

func qux(...func()) {}
func f()            {} //@item(vVarArg, "f", "func()", "func")

func _() {
	qux(f) //@snippet(re"()\\)", vVarArg, "f")
}

func _() {
	foo(0, []string{}...) //@complete(re"()\\)")
}

-- variadic_intf.go --
package variadic

type baz interface {
	baz()
}

func wantsBaz(...baz) {}

type bazImpl int

func (bazImpl) baz() {}

func _() {
	var (
		impls []bazImpl //@item(vImplSlice, "impls", "[]bazImpl", "var")
		impl  bazImpl   //@item(vImpl, "impl", "bazImpl", "var")
		bazes []baz     //@item(vIntfSlice, "bazes", "[]baz", "var")
	)

	wantsBaz() //@rank(re"()\\)", vImpl, vImplSlice),rank(re"()\\)", vIntfSlice, vImplSlice)
}


================================================
FILE: gopls/internal/test/marker/testdata/configuration/static.txt
================================================
This test confirms that gopls honors configuration even if the client does not
support dynamic configuration.

-- capabilities.json --
{
	"configuration": false
}

-- settings.json --
{
	"usePlaceholders": true,
	"analyses": {
		"composites": false
	}
}

-- go.mod --
module example.com/config

go 1.18

-- a/a.go --
package a

import "example.com/config/b"

func Identity[P ~int](p P) P { //@item(Identity, "Identity", "", "")
	return p
}

func _() {
	_ = b.B{2}
	_ = Identi //@snippet(re"ti()", Identity, "Identity(${1:p P})"), diag("Ident", re"(undefined|undeclared)")
}

-- b/b.go --
package b

type B struct {
	F int
}


================================================
FILE: gopls/internal/test/marker/testdata/definition/asm.txt
================================================
This test exercises the Definition request in a Go assembly file.

For now we support only references to package-level symbols defined in
the same package or a dependency.

Repeatedly jumping to Definition on ff ping-pongs between the Go and
assembly declarations.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

import _ "fmt"
import _ "example.com/b"

func ff() //@ loc(ffgo, "ff"), def("ff", ffasm)

var _ = ff // pacify unusedfunc analyzer

-- a/asm.s --
// portable assembly

TEXT ·ff(SB), $16                       //@ loc(ffasm, "ff"), def("ff", ffgo)
        CALL    example·com∕b·B         //@ def("com", bB)
        JMP     ·ff                     //@ def("ff", ffgo)
	JMP     label			//@ def("label", label)
label:					//@ loc(label,"label")
        RET

-- b/b.go --
package b

func B() {} //@ loc(bB, "B")


================================================
FILE: gopls/internal/test/marker/testdata/definition/branch.txt
================================================
This test checks definition operations in branch statements break, goto and continue.

We suppress staticheck since it also gives a diagnostic
about the break being ineffective.

-- settings.json --
{
	"staticcheck": false
}

-- go.mod --
module mod.com

go 1.18

-- a/a.go --
package a

import "log"

func BreakLoop() {
	for i := 0; i < 10; i++ {
		if i > 6 {
			break //@def("break", rbrace1)
		}
	} //@loc(rbrace1, `}`)
}

func BreakNestedLoop() {
	for i := 0; i < 10; i++ {
		for j := 0; j < 5; j++ {
			if j > 1 {
				break //@def("break", rbrace2)
			}
		} //@loc(rbrace2, `}`)
	}
}

func BreakNestedLoopWithLabel() {
	Outer:
	for i := 0; i < 10; i++ {
		for j := 0; j < 5; j++ {
			if j > 1 {
				break Outer//@def("break", outerparen)
			}
		}
	} //@loc(outerparen, `}`)
}

func BreakSwitch(i int) {
	switch i {
		case 1:
			break //@def("break", rbrace4)
		case 2:
			log.Printf("2")
		case 3:
			log.Printf("3")
	} //@loc(rbrace4, `}`)
}

func BreakSwitchLabel(i int) {
loop:
	for {
		switch i {
		case 1:
			break loop //@def("break", loopparen)
		case 2:
			log.Printf("2")
		case 3:
			continue loop
		}
	} //@loc(loopparen, `}`)
}

func BreakSelect(c, quit chan int) {
	x, y := 0, 1
	for {
		select {
		case c <- x:
			x, y = y, x+y
		break //@def("break", rbrace5)
		case <-quit:
			log.Println("quit")
			return
		} //@loc(rbrace5, `}`)
	}
}

func BreakWithContinue() {
	for j := 0; j < 5; j++ {
		if (j < 4) {
			continue
		}
		break //@def("break", rbrace6)
	} //@loc(rbrace6, `}`)
}

func GotoNestedLoop() {
	Outer: //@loc(outer, "Outer")
	for i := 0; i < 10; i++ {
		for j := 0; j < 5; j++ {
			if (j > 1) {
				goto Outer//@def("goto", outer)
			}
		}
	}
}

func ContinueLoop() {
	for j := 0; j < 5; j++ { //@loc(for3, `for`)
		if (j < 4) {
			continue //@def("continue", for3)
		}
		break
	}
}

func ContinueDoubleLoop() {
	for i := 0; i < 10; i++ { //@loc(for4, `for`)
		for j := 0; j < 5; j++ {
			if (j > 1) {
				break
			}
		}
		if (i > 7) {
			continue//@def("continue", for4)
		}
	}
}

func BreakInBlockStmt() {
	for {
		if 0 < 10 {
			{
				break //@def("break", rbrace9)
			}
		}
	} //@loc(rbrace9, `}`)
}

func BreakInLabeledStmt() {
	outer:
	for {
		goto inner
	inner:
		break outer //@def("break", for5)
	} //@loc(for5, `}`)
}

func BreakToLabel(n int) {
	outer1:
		switch n {
			case 1:
				print("1")
				for i := 0; i < 10; i++ {
				if i > 3 {
					break outer1 //@def("break", outer1)
				}
			}
		} //@loc(outer1, "}")
}

func ContinueToLabel(n int) {
	outer1:
		for { //@loc(outer2, "for")
			switch n {
			case 1:
				print("1")
				for i := 0; i < 10; i++ {
					if i > 3 {
						continue outer1 //@def("continue", outer2)
					}
				}
			}
		}
}


================================================
FILE: gopls/internal/test/marker/testdata/definition/branch_issue73797.txt
================================================
This test checks the case of a definition operation on a "continue" with an invalid label.
In gotip, the typechecker no longer associates the continue statement with its invalid label,
so this test case should only be run for go1.24 or earlier.
See the related change in go/types: https://go-review.git.corp.google.com/c/go/+/638257

-- flags --
-ignore_extra_diags

-- go.mod --
module mod.com

go 1.18

-- a/a.go --
package a

func InvalidLabel() {
    label:
	for i := 0; i < 10; i++ {
	}
	for i := 0; i < 10; i++ { //@loc(for, "for")
		continue label //@def("continue", for)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/definition/branch_issue73797_go124.txt
================================================
This test checks the case of a definition operation on a "continue" with an invalid label.
In gotip, the typechecker no longer associates the continue statement with its invalid label,
so this test case should only be run for go1.24 or earlier.
See the related change in go/types: https://go-review.git.corp.google.com/c/go/+/638257

-- flags --
-max_go=go1.24
-ignore_extra_diags

-- go.mod --
module mod.com

go 1.18

-- a/a.go --
package a

func InvalidLabel() {
    label:
	for i := 0; i < 10; i++ {
	}
	for i := 0; i < 10; i++ {
		continue label //@def("continue")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/definition/cgo.txt
================================================
This test is ported from the old marker tests.
It tests hover and definition for cgo declarations.

-- flags --
-cgo

-- go.mod --
module cgo.test

go 1.18

-- cgo/cgo.go --
package cgo

/*
#include <stdio.h>
#include <stdlib.h>

void myprint(char* s) {
	printf("%s\n", s);
}
*/
import "C"

import (
	"fmt"
	"unsafe"
)

func Example() { //@loc(cgoexample, "Example"), item(cgoexampleItem, "Example", "func()", "func")
	fmt.Println()
	cs := C.CString("Hello from stdio\n")
	C.myprint(cs)
	C.free(unsafe.Pointer(cs))
}

func _() {
	Example() //@hover("ample", "Example", hoverExample), def("ample", cgoexample), complete(re"()ample", cgoexampleItem)
}

-- @hoverExample --
```go
func Example()
```

---

[`cgo.Example` on pkg.go.dev](https://pkg.go.dev/cgo.test/cgo#Example)
-- usecgo/usecgo.go --
package cgoimport

import (
	"cgo.test/cgo"
)

func _() {
	cgo.Example() //@hover("ample", "Example", hoverImportedExample), def("ample", cgoexample), complete(re"()ample", cgoexampleItem)
}
-- @hoverImportedExample --
```go
func cgo.Example()
```

---

[`cgo.Example` on pkg.go.dev](https://pkg.go.dev/cgo.test/cgo#Example)


================================================
FILE: gopls/internal/test/marker/testdata/definition/comment.txt
================================================
This test executes definition requests over doc links.

-- go.mod --
module mod.com

go 1.19

-- path/path.go --
package path

func Join() //@loc(Join, "Join")

-- a.go --
package p

import "strconv" //@loc(strconv, `"strconv"`)
import pathpkg "mod.com/path"
import _ "unsafe"

const NumberBase = 10 //@loc(NumberBase, "NumberBase")

// [Conv] converts s to an int. //@def("Conv", Conv)
func Conv(s string) int { //@loc(Conv, "Conv")
	// [strconv.ParseInt] parses s and returns the integer corresponding to it. //@def("strconv", strconv)
	// [NumberBase] is the base to use for number parsing. //@def("NumberBase", NumberBase)
	i, _ := strconv.ParseInt(s, NumberBase, 64)
	return int(i)
}

type T struct {
	Field int //@ loc(Field, "Field")
}

func (T) Method() {} //@ loc(Method, "Method")

// The declared and imported names of the package both work:
// [path.Join]    //@ def("Join", Join)
// [pathpkg.Join] //@ def("Join", Join)
//
// Also, both [T.Field] and //@ def("Field", Field)
// [T.Method] are supported. //@ def("Method", Method)
func _() {
	pathpkg.Join()
}

// Built-in and unsafe symbols work too.
// [unsafe.Pointer] //@def("Pointer", UNSAFE)
// [unsafe.Slice]   //@def("Slice", UNSAFE)
// [int]            //@def("int", BUILTIN)
// [error]          //@def("error", BUILTIN)
// [error.Error]    //@def("Error", BUILTIN)
func _()


================================================
FILE: gopls/internal/test/marker/testdata/definition/embed.txt
================================================
This test checks definition and hover operations over embedded fields and methods.

Its size expectations assume a 64-bit machine,
and correct sizes information requires go1.21.

-- flags --
-skip_goarch=386,arm

-- go.mod --
module mod.com

go 1.18

-- a/a.go --
package a

type A string //@loc(AString, "A")

func (_ A) Hi() {} //@loc(AHi, "Hi")

type S struct {
	Field int //@loc(SField, "Field")
	R         // embed a struct
	H         // embed an interface
}

type R struct {
	Field2 int //@loc(RField2, "Field2")
}

func (r R) Hey() {} //@loc(RHey, "Hey")

type H interface { //@loc(H, "H")
	Goodbye() //@loc(HGoodbye, "Goodbye")
}

type I interface { //@loc(I, "I")
	B() //@loc(IB, "B")
	J
}

type J interface { //@loc(J, "J")
	Hello() //@loc(JHello, "Hello")
}

-- b/b.go --
package b

import "mod.com/a" //@loc(AImport, re"\"[^\"]*\"")

type embed struct {
	F int //@loc(F, "F")
}

func (embed) M() //@loc(M, "M")

type Embed struct {
	embed
	*a.A
	a.I
	a.S
}

func _() {
	e := Embed{}
	e.Hi()      //@def("Hi", AHi),hover("Hi", "Hi", AHi)
	e.B()       //@def("B", IB),hover("B", "B", IB)
	_ = e.Field     //@def("Field", SField),hover("Field", "Field", SField)
	_ = e.Field2    //@def("Field2", RField2),hover("Field2", "Field2", RField2)
	e.Hello()   //@def("Hello", JHello),hover("Hello", "Hello",JHello)
	e.Hey()     //@def("Hey", RHey),hover("Hey", "Hey", RHey)
	e.Goodbye() //@def("Goodbye", HGoodbye),hover("Goodbye", "Goodbye", HGoodbye)
	e.M() //@def("M", M),hover("M", "M", M)
	_ = e.F //@def("F", F),hover("F", "F", F)
}

type aAlias = a.A //@loc(aAlias, "aAlias")

type S1 struct { //@loc(S1, "S1")
	F1     int //@loc(S1F1, "F1")
	S2         //@loc(S1S2, "S2"),def("S2", S2),hover("S2", "S2", S2)
	a.A        //@def("A", AString),hover("A", "A", aA)
	aAlias     //@def("a", aAlias),hover("a", "aAlias", aAlias)
}

type S2 struct { //@loc(S2, "S2")
	F1   string //@loc(S2F1, "F1")
	F2   int    //@loc(S2F2, "F2")
	*a.A        //@def("A", AString),def("a",AImport)
}

type S3 struct {
	F1 struct {
		a.A //@def("A", AString)
	}
}

func Bar() {
	var x S1    //@def("S1", S1),hover("S1", "S1", S1)
	_ = x.S2    //@def("S2", S1S2),hover("S2", "S2", S1S2)
	_ = x.F1    //@def("F1", S1F1),hover("F1", "F1", S1F1)
	_ = x.F2    //@def("F2", S2F2),hover("F2", "F2", S2F2)
	_ = x.S2.F1 //@def("F1", S2F1),hover("F1", "F1", S2F1)
}

-- b/c.go --
package b

var _ = S1{ //@def("S1", S1),hover("S1", "S1", S1)
	F1: 99, //@def("F1", S1F1),hover("F1", "F1", S1F1)
}

-- @AHi --
```go
func (a.A) Hi()
```

---

[`(a.A).Hi` on pkg.go.dev](https://pkg.go.dev/mod.com/a#A.Hi)
-- @F --
```go
field F int // through embed
```

---

@loc(F, "F")


---

[`(b.Embed).F` on pkg.go.dev](https://pkg.go.dev/mod.com/b#Embed.F)
-- @HGoodbye --
```go
func (a.H) Goodbye()
```

---

@loc(HGoodbye, "Goodbye")


---

[`(a.H).Goodbye` on pkg.go.dev](https://pkg.go.dev/mod.com/a#H.Goodbye)
-- @IB --
```go
func (a.I) B()
```

---

@loc(IB, "B")


---

[`(a.I).B` on pkg.go.dev](https://pkg.go.dev/mod.com/a#I.B)
-- @JHello --
```go
func (a.J) Hello()
```

---

@loc(JHello, "Hello")


---

[`(a.J).Hello` on pkg.go.dev](https://pkg.go.dev/mod.com/a#J.Hello)
-- @M --
```go
func (embed) M()
```

---

[`(b.Embed).M` on pkg.go.dev](https://pkg.go.dev/mod.com/b#Embed.M)
-- @RField2 --
```go
field Field2 int // through S, R
```

---

@loc(RField2, "Field2")


---

[`(a.R).Field2` on pkg.go.dev](https://pkg.go.dev/mod.com/a#R.Field2)
-- @RHey --
```go
func (r a.R) Hey()
```

---

[`(a.R).Hey` on pkg.go.dev](https://pkg.go.dev/mod.com/a#R.Hey)
-- @S1 --
```go
type S1 struct {
	F1     int //@loc(S1F1, "F1")
	S2         //@loc(S1S2, "S2"),def("S2", S2),hover("S2", "S2", S2)
	a.A        //@def("A", AString),hover("A", "A", aA)
	aAlias     //@def("a", aAlias),hover("a", "aAlias", aAlias)
}
```

---

```go
// Embedded fields:
F2 int // through S2 
```

---

[`b.S1` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S1)
-- @S1F1 --
```go
field F1 int
```

---

@loc(S1F1, "F1")


---

[`(b.S1).F1` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S1.F1)
-- @S1S2 --
```go
field S2 S2
```

---

@loc(S1S2, "S2"),def("S2", S2),hover("S2", "S2", S2)


---

[`(b.S1).S2` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S1.S2)
-- @S2 --
```go
field S2 S2 // size=32 (0x20), offset=8
```

---

@loc(S1S2, "S2"),def("S2", S2),hover("S2", "S2", S2)


---

[`(b.S1).S2` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S1.S2)
-- @S2F1 --
```go
field F1 string
```

---

@loc(S2F1, "F1")


---

[`(b.S2).F1` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S2.F1)
-- @S2F2 --
```go
field F2 int // through S2
```

---

@loc(S2F2, "F2")


---

[`(b.S2).F2` on pkg.go.dev](https://pkg.go.dev/mod.com/b#S2.F2)
-- @SField --
```go
field Field int // through S
```

---

@loc(SField, "Field")


---

[`(a.S).Field` on pkg.go.dev](https://pkg.go.dev/mod.com/a#S.Field)
-- @aA --
```go
field A a.A // size=16 (0x10), offset=40 (0x28)
```
-- @aAlias --
```go
field aAlias aAlias // size=16 (0x10), offset=56 (0x38)
```

---

@def("a", aAlias),hover("a", "aAlias", aAlias)


================================================
FILE: gopls/internal/test/marker/testdata/definition/import.txt
================================================
This test checks definition and hover over imports.

-- go.mod --
module mod.com

go 1.18
-- foo/foo.go --
package foo

type Foo struct{}

// DoFoo does foo.
func DoFoo() {} //@loc(DoFoo, "DoFoo")
-- bar/bar.go --
package bar

import (
	myFoo "mod.com/foo" //@loc(myFoo, "myFoo")
)

var _ *myFoo.Foo //@def("myFoo", myFoo),hover("myFoo", "myFoo", myFoo)
-- bar/dotimport.go --
package bar

import . "mod.com/foo"

func _() {
	// variable of type foo.Foo
	var _ Foo //@hover("_", "_", FooVar)

	DoFoo() //@hover("DoFoo", "DoFoo", DoFoo)
}
-- @DoFoo --
```go
func DoFoo()
```

---

DoFoo does foo.


---

[`foo.DoFoo` on pkg.go.dev](https://pkg.go.dev/mod.com/foo#DoFoo)
-- @FooVar --
```go
var _ Foo
```

---

variable of type foo.Foo
-- @myFoo --
```go
package foo
```

---

[`myFoo` on pkg.go.dev](https://pkg.go.dev/mod.com/foo)


================================================
FILE: gopls/internal/test/marker/testdata/definition/misc.txt
================================================
This test exercises miscellaneous definition and hover requests.

Its size expectations assume a 64-bit machine.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- go.mod --
module mod.com

go 1.16

-- flags --
-skip_goarch=386,arm

-- a.go --
package a //@loc(aPackage, re"package (a)"),hover(aPackage, aPackage, aPackage)

var (
	// x is a variable.
	x string //@loc(x, "x"),hover(x, x, hoverx)
)

// Constant block. When I hover on h, I should see this comment.
const (
	// When I hover on g, I should see this comment.
	g = 1 //@hover("g", "g", hoverg)

	h = 2 //@hover("h", "h", hoverh)
)

// z is a variable too.
var z string //@loc(z, "z"),hover(z, z, hoverz)

func AStuff() { //@loc(AStuff, "AStuff")
	x := 5
	Random2(x) //@def("dom2", Random2)
	Random()   //@def("()", Random)
}

type H interface { //@loc(H, "H")
	Goodbye()
}

type I interface { //@loc(I, "I")
	B()
	J
}

type J interface { //@loc(J, "J")
	Hello()
}

func _() {
	// 1st type declaration block
	type (
		a struct { //@hover("a", "a", hoverDeclBlocka)
			x string
		}
	)

	// 2nd type declaration block
	type (
		// b has a comment
		b struct{} //@hover("b", "b", hoverDeclBlockb)
	)

	// 3rd type declaration block
	type (
		// c is a struct
		c struct { //@hover("c", "c", hoverDeclBlockc)
			f string
		}

		d string //@hover("d", "d", hoverDeclBlockd)
	)

	type (
		e struct { //@hover("e", "e", hoverDeclBlocke)
			f float64
		} // e has a comment
	)
}

var (
	hh H //@hover("H", "H", hoverH)
	ii I //@hover("I", "I", hoverI)
	jj J //@hover("J", "J", hoverJ)
)
-- a_test.go --
package a

import (
	"testing"
)

func TestA(t *testing.T) { //@hover("TestA", "TestA", hoverTestA)
}
-- random.go --
package a

func Random() int { //@loc(Random, "Random")
	y := 6 + 7
	return y
}

func Random2(y int) int { //@loc(Random2, "Random2"),loc(RandomParamY, "y")
	return y //@def("y", RandomParamY),hover("y", "y", hovery)
}

type Pos struct {
	x, y int //@loc(PosX, "x"),loc(PosY, "y")
}

// Typ has a comment. Its fields do not.
type Typ struct{ field string } //@loc(TypField, "field")

func _() {
	x := &Typ{}
	_ = x.field //@def("field", TypField),hover("field", "field", hoverfield)
}

func (p *Pos) Sum() int { //@loc(PosSum, "Sum")
	return p.x + p.y //@hover("x", "x", hoverpx)
}

func _() {
	var p Pos
	_ = p.Sum() //@def("()", PosSum),hover(re"Sum()", `Sum`, hoverSum)
}
-- @aPackage --
```go
package a
```

---

 - Package path: mod.com
 - Module: mod.com
 - Language version: go1.16
-- @hoverDeclBlocka --
```go
type a struct { // size=16 (0x10)
	x string
}
```

---

1st type declaration block
-- @hoverDeclBlockb --
```go
type b struct{} // size=0
```

---

b has a comment
-- @hoverDeclBlockc --
```go
type c struct { // size=16 (0x10)
	f string
}
```

---

c is a struct
-- @hoverDeclBlockd --
```go
type d string // size=16 (0x10)
```

---

3rd type declaration block
-- @hoverDeclBlocke --
```go
type e struct { // size=8
	f float64
}
```

---

e has a comment
-- @hoverH --
```go
type H interface {
	Goodbye()
}
```

---

[`a.H` on pkg.go.dev](https://pkg.go.dev/mod.com#H)
-- @hoverI --
```go
type I interface {
	B()
	J
}
```

---

```go
func (J) Hello()
```

---

[`a.I` on pkg.go.dev](https://pkg.go.dev/mod.com#I)
-- @hoverJ --
```go
type J interface {
	Hello()
}
```

---

[`a.J` on pkg.go.dev](https://pkg.go.dev/mod.com#J)
-- @hoverSum --
```go
func (p *Pos) Sum() int
```

---

[`(a.Pos).Sum` on pkg.go.dev](https://pkg.go.dev/mod.com#Pos.Sum)
-- @hoverTestA --
```go
func TestA(t *testing.T)
```
-- @hoverfield --
```go
field field string
```
-- @hoverg --
```go
const g untyped int = 1
```

---

When I hover on g, I should see this comment.
-- @hoverh --
```go
const h untyped int = 2
```

---

Constant block. When I hover on h, I should see this comment.
-- @hoverpx --
```go
field x int
```

---

@loc(PosX, "x"),loc(PosY, "y")
-- @hoverx --
```go
var x string
```

---

x is a variable.
-- @hovery --
```go
var y int
```
-- @hoverz --
```go
var z string
```

---

z is a variable too.


================================================
FILE: gopls/internal/test/marker/testdata/definition/nearby.txt
================================================
This test checks the "nearby" logic of golang.objectsAt
as used by Definition. The query is on the "*" of "*T"
yet resolves to T.

-- go.mod --
module mod.com
go 1.18

-- a/a.go --
package a

type T int	//@ loc(T, "T")

var _ * T	//@ def("*", T)


================================================
FILE: gopls/internal/test/marker/testdata/definition/return.txt
================================================
This test checks definition operations in function return statements. 
Go to definition on 'return' should go to the result parameter list.

-- go.mod --
module mod.com

go 1.18

-- a/a.go --
package a

func Hi() string { //@loc(HiReturn, "string")
    return "Hello" //@def("return", HiReturn)
}

func Bye() (int, int, int) { //@loc(ByeReturn, "(int, int, int)")
    return 1, 2, 3 //@def("return", ByeReturn)
}

func TestLit() {
    f := func(a, b int) bool { return a*b < 100 } //@loc(FuncLitReturn, "bool"),def("return", FuncLitReturn)
    f(1, 2)
}


================================================
FILE: gopls/internal/test/marker/testdata/definition/standalone.txt
================================================
This test checks the behavior of standalone packages, in particular documenting
our failure to support test files as standalone packages (golang/go#64233).

-- go.mod --
module golang.org/lsptests/a

go 1.20

-- a.go --
package a

func F() {} //@loc(F, "F")

-- standalone.go --
//go:build ignore
package main

import "golang.org/lsptests/a"

func main() {
	a.F() //@def("F", F)
}

-- standalone_test.go --
//go:build ignore
package main //@diag("main", re"No packages found")

import "golang.org/lsptests/a"

func main() {
	a.F() //@hovererr("F", "no package")
}

-- standalone_x_test.go --
//go:build ignore
package main_test //@diag("main", re"No packages found")

import "golang.org/lsptests/a"

func main() {
	a.F() //@hovererr("F", "no package")
}



================================================
FILE: gopls/internal/test/marker/testdata/definition/standalone_issue64557.txt
================================================
This test checks that we can load standalone files that use cgo.

-- flags --
-cgo

-- go.mod --
module example.com

-- main.go --
//go:build ignore

package main

import (
	"C"

	"example.com/a"
)

func F() {} //@loc(F, "F")

func main() {
	F() //@def("F", F)
	println(a.A) //@def("A", A)
}

-- a/a.go --
package a

const A = 0 //@loc(A, "A")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/addgowork.txt
================================================
This test demonstrates diagnostics for adding a go.work file.

Quick-fixes change files on disk, so are tested by integration tests.

TODO(rfindley): improve the "cannot find package" import errors.

-- skip --
These diagnostics are no longer produced, because in golang/go#57979
(zero-config gopls) we made gopls function independent of a go.work file.
Preserving this test as we may want to re-enable the code actions go manage
a go.work file.

Note that in go.dev/issue/60584#issuecomment-1622238115, this test was flaky.
However, critical error logic has since been rewritten.

-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main //@diag("main", re"add a go.work file")

import "mod.com/a/lib" //@diag("\"mod.com", re"cannot find package")

func main() {
	_ = lib.C
}

-- a/lib/lib.go --
package lib //@diag("lib", re"add a go.work file")

const C = "b"
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main //@diag("main", re"add a go.work file")

import "mod.com/b/lib" //@diag("\"mod.com", re"cannot find package")

func main() {
	_ = lib.C
}

-- b/lib/lib.go --
package lib //@diag("lib", re"add a go.work file")

const C = "b"


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/analyzers.txt
================================================
Test of warning diagnostics from various analyzers:
copylocks, printf, slog, tests, timeformat, nilness, and cgocall.

-- settings.json --
{
	"pullDiagnostics": true
}

-- go.mod --
module example.com
go 1.23

-- flags --
-min_go_command=go1.23
-cgo

-- bad/bad_test.go --
package bad

import (
	"fmt"
	"iter"
	"log/slog"
	"sync"
	"testing"
	"time"
)

// copylocks
func _() {
	var x sync.Mutex
	_ = x //@diag("x", re"assignment copies lock value to _: sync.Mutex")
}

// printf
func _() {
	printfWrapper("%s") //@diag(re`%s`, re"example.com/bad.printfWrapper format %s reads arg #1, but call has 0 args")
}

func printfWrapper(format string, args ...any) {
	fmt.Printf(format, args...)
}

// tests
func Testbad(t *testing.T) { //@diag("Testbad", re"Testbad has malformed name: first letter after 'Test' must not be lowercase")
}

// timeformat
func _() {
	now := time.Now()
	fmt.Println(now.Format("2006-02-01")) //@diag("2006-02-01", re"2006-02-01 should be 2006-01-02")
}

// nilness
func _(ptr *int) {
	if ptr == nil {
		_ = *ptr //@diag("*ptr", re"nil dereference in load")
	}
}

// unusedwrite
func _(s struct{x int}) {
	s.x = 1  //@diag("x", re"unused write to field x")
}

// slog
func _() {
	slog.Info("msg", 1) //@diag("1", re`slog.Info arg "1" should be a string or a slog.Attr`)
}

// waitgroup
func _() {
	var wg sync.WaitGroup
	go func() {
		wg.Add(1) //@diag("(", re"WaitGroup.Add called from inside new goroutine")
	}()
}

// inline
func _() {
	f()  //@diag("f", re"Call of bad.f should be inlined")
}

//go:fix inline
func f() { fmt.Println(1) }

// recursiveiter
func F() iter.Seq[int] {
	return func(yield func(int) bool) {
		for range F() {} //@ diag("range", re"inefficient recursion in iterator F")
	}
}

-- cgocall/cgocall.go --
package cgocall

// Note: this test must be in a separate package, as the unsafe import
// silences the unusedwrite analyzer.
import "unsafe"

// void f(void *ptr) {}
import "C"

// cgocall
func _(c chan bool) {
	C.f(unsafe.Pointer(&c)) //@ diag("unsafe", re"passing Go type with embedded pointer to C")
}

-- maprange/maprange.go --
package maprange

import "maps"

func _(m map[int]int) {
	for range maps.Keys(m) {} //@ diag("maps.Keys", re"unnecessary and inefficient call of maps.Keys")
}

-- unusedresult/unusedresult.go --
package unusedresult

import "fmt"

func _() {
	fmt.Appendf(nil, "%d", 1) //@ diag("fmt.Appendf", re"result.*not used")
}

-- staticcheck/staticcheck.go --
package staticcheck

// staticcheck includes hundreds of other analyzers.
// Here we test only two: one enabled by default, one disabled.

func S1000(ch chan int) {
	select { case <-ch: } //@ diag("select", re"use .*receive instead of select")
}

func S1011(x, y []int) {
	for _, e := range y {
		x = append(x, e) // no "replace loop with append" diagnostic
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/excludedfile.txt
================================================
This test demonstrates diagnostics for various forms of file exclusion.

Note: this test used to also check the errors when a file was excluded due to
an inactive module, or mismatching GOOS/GOARCH, comment, but with zero-config
gopls (golang/go#57979) and improved build tag support (golang/go#29202), we no
longer get these errors.

-- go.work --
go 1.21

use (
	./a
)
-- a/go.mod --
module mod.com/a

go 1.18

-- a/a.go --
package a

-- a/a_plan9.go --
package a // Not excluded, due to improved build tag support.

-- a/a_ignored.go --
//go:build skip
package a //@diag(re"package (a)", re"excluded due to its build tags")

-- b/go.mod --
module mod.com/b

go 1.18

-- b/b.go --
package b // Not excluded, due to zero-config gopls.



================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/generated.txt
================================================
Test of "undeclared" diagnostic in generated code.

-- settings.json --
{
	"pullDiagnostics": true
}

-- go.mod --
module example.com
go 1.12

-- generated.go --
// Code generated by generator.go. DO NOT EDIT.

package generated

func _() {
	var y int //@diag("y", re"declared (and|but) not used")
}

-- generator.go --
package generated

func _() {
	var x int //@diag("x", re"declared (and|but) not used")
}


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/initcycle.txt
================================================
This test verifies that gopls spreads initialization cycle errors across
multiple declarations.

We set -ignore_extra_diags due to golang/go#65877: gopls produces redundant
diagnostics for initialization cycles.

-- flags --
-ignore_extra_diags

-- p.go --
package p

var X = Y //@diag("X", re"initialization cycle")

var Y = Z //@diag("Y", re"initialization cycle")

var Z = X //@diag("Z", re"initialization cycle")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue56943.txt
================================================
This test verifies that we produce diagnostics related to mismatching
unexported interface methods in non-workspace packages.

Previously, we would fail to produce a diagnostic because we trimmed the AST.
See golang/go#56943.
-- settings.json --
{
	"pullDiagnostics": true
}

-- main.go --
package main

import (
	"go/ast"
	"go/token"
)

func main() {
	var a int               //@diag(re"(a) int", re"declared.*not used")
	var _ ast.Expr = node{} //@diag("node{}", re"missing.*exprNode")
}

type node struct{}

func (node) Pos() token.Pos { return 0 }
func (node) End() token.Pos { return 0 }


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue59005.txt
================================================
This test verifies that we don't drop type checking errors on the floor when we
fail to compute positions for their related errors.

-- go.mod --
module play.ground

-- p.go --
package p

import (
	. "play.ground/foo"
)

const C = 1 //@diag("C", re"C already declared through dot-import")
var _ = C

-- foo/foo.go --
package foo

const C = 2


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue60544.txt
================================================
This test exercises a crash due to treatment of "comparable" in methodset
calculation (golang/go#60544).

-- main.go --
package main

type X struct{}

func (X) test(x comparable) {} //@diag("comparable", re"outside a type constraint")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue60605.txt
================================================
This test verifies that we can export constants with unknown kind.
Previously, the exporter would panic while attempting to convert such constants
to their target type (float64, in this case).

-- go.mod --
module mod.txt/p

go 1.20
-- p.go --
package p

const EPSILON float64 = 1e- //@diag(re"1e-()", re"exponent has no digits")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue64547.txt
================================================
This test checks the fix for golang/go#64547: the lostcancel analyzer reports
diagnostics that overflow the file.

-- p.go --
package p

import "context"

func _() {
	_, cancel := context.WithCancel(context.Background()) //@diag("_, cancel", re"not used on all paths")
	if false {
		cancel()
	}
} //@diag("}", re"may be reached without using the cancel")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue67360.txt
================================================
Regression test for #67360.

This file causes go list to report a "use of internal package
cmd/internal/browser" error. (It is important that this be a real
internal std package.) The line directive caused the position of the
error to lack a column. A bug in the error parser filled in 0, not 1,
for the missing information, and this is an invalid value in the
1-based UTF-8 domain, leading to a panic.

-- foo.go --
//line foo.go:1
package main                    //@ diag(re"package", re"internal package.*not allowed")
import _ "cmd/internal/browser" //@ diag(re`"`, re"could not import")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue69505.txt
================================================
This test checks that diagnostics ranges computed with the TypeErrorEndPos
heuristic span at least a full token.

-- go.mod --
module example.com

go 1.21

-- main.go --
package main

import "example.com/foo-bar" //@ diag(re`"[^"]*"`, re`not used`, exact=true)

func f(int) {}

func main() {
	var x int
	_ = x + 1.e+0i //@ diag("1.e+0i", re`truncated`, exact=true)
}

-- foo-bar/baz.go --
package foo


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue70791.txt
================================================
In addition to the Diagnostic, the SA4023 analyzer reports a
RelatedInformation at the position of b.B, in an another package.
Since this is in a dependency package, we cannot resolve to
protocol.Location coordinates. This used to trigger an assertion, but
now we resolve the location approximately.

This is a regression test for #70791.

-- settings.json --
{"analyses": {"SA4023": true}}

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

import "example.com/b"

var _ = b.B() == nil //@ diag("b.B", re"comparison is never true")

-- b/b.go --
package b

func B() any { return (*int)(nil) }





================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/issue71812.txt
================================================
This input causes the unreachable analyzer to report a diagnostic
about the var decl statement. Since the computed End pos of
ast.StructType is beyond EOF, validation of SuggestedFixes fails.
This used to trigger an assertion in gopls' analysis driver.

See golang/go#71659 (and also #71812).

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a
func _() { return; var x struct{


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/osarch_suffix.txt
================================================
This test verifies that we add an [os,arch] suffix to each diagnostic
that doesn't appear in the default build (=runtime.{GOOS,GOARCH}).

See golang/go#65496.

The two p/*.go files below are written to trigger the same diagnostic
(range, message, source, etc) but varying only by URI.

In the q test, a single location in the common code q.go has two
diagnostics, one of which is tagged.

This test would fail on openbsd/riscv64 because it will be the same as
the default build, so we skip that platform. And it would fail on
*/riscv64 merely because it produces a diagnostic that doesn't include
the riscv64 component (since it's the default). So we disable it for
that GOOS or GOARCH. But the purpose of the test is not coverage
across all configurations, only to test the mechanism in some configs.

-- flags --
-skip_goos=openbsd
-skip_goarch=riscv64

-- go.mod --
module example.com

-- p/p.go --
package p

var _ fmt.Stringer //@diag("fmt", re"unde.*: fmt$")

-- p/p_openbsd_riscv64.go --
package p

var _ fmt.Stringer //@diag("fmt", re"unde.*: fmt \\[openbsd,riscv64\\]")

-- q/q_default.go --
//+build !openbsd && !riscv64

package q

func f(int) int

-- q/q_openbsd_riscv64.go --
package q

func f(string) int

-- q/q.go --
package q

var _ = f() //@ diag(")", re`.*want \(string\) \[openbsd,riscv64\]`), diag(")", re`.*want \(int\)$`)


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/parseerr.txt
================================================

This test exercises diagnostics produced for syntax errors.

Because parser error recovery can be quite lossy, diagnostics
for type errors are suppressed in files with syntax errors;
see issue #59888. But diagnostics are reported for type errors
in well-formed files of the same package.

-- go.mod --
module example.com
go 1.12

-- bad.go --
package p

func f() {
	append("") // no diagnostic for type error in file containing syntax error
}

func .() {} //@diag(re"func ().", re"expected 'IDENT', found '.'")

-- good.go --
package p

func g() {
	append("") //@diag(re`""`, re"a slice")
}


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/rundespiteerrors.txt
================================================
This test verifies that analyzers without RunDespiteErrors are not
executed on a package containing type errors (see issue #54762).

-- go.mod --
module example.com
go 1.12

-- a.go --
package a

func _() {
	// A type error.
	_ = 1 + "" //@diag(`1 + ""`, re"mismatched types|cannot convert")

	// A violation of an analyzer for which RunDespiteErrors=false:
	// no (simplifyrange, warning) diagnostic is produced; the diag
	// comment is merely illustrative.
	for _ = range "" { //diag("for _", "simplify range expression", )

	}
}


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/stdversion.txt
================================================
Test of "too new" diagnostics from the stdversion analyzer.

This test references go1.21 symbols from std, but the analyzer itself
depends on the go1.22 behavior of versions.FileVersion.

See also go/analysis/passes/stdversion/testdata/test.txtar,
which runs the same test in the analysistest framework.

-- flags --
-min_go_command=go1.22

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

import "go/types"

func _() {
	// old package-level type
	var _ types.Info // ok: defined by go1.0

	// new field of older type
	_ = new(types.Info).FileVersions //@diag("FileVersions", re`types.FileVersions requires go1.22 or later \(module is go1.21\)`)

	// new method of older type
	_ = new(types.Info).PkgNameOf //@diag("PkgNameOf", re`types.PkgNameOf requires go1.22 or later \(module is go1.21\)`)

	// new package-level type
	var a types.Alias //@diag("Alias", re`types.Alias requires go1.22 or later \(module is go1.21\)`)

	// new method of new type
	a.Underlying() // no diagnostic
}

-- sub/go.mod --
module example.com/sub

go 1.21

-- sub/sub.go --
package sub

import "go/types"

func _() {
	// old package-level type
	var _ types.Info // ok: defined by go1.0

	// new field of older type
	_ = new(types.Info).FileVersions //@diag("FileVersions", re`types.FileVersions requires go1.22 or later \(module is go1.21\)`)

	// new method of older type
	_ = new(types.Info).PkgNameOf //@diag("PkgNameOf", re`types.PkgNameOf requires go1.22 or later \(module is go1.21\)`)

	// new package-level type
	var a types.Alias //@diag("Alias", re`types.Alias requires go1.22 or later \(module is go1.21\)`)

	// new method of new type
	a.Underlying() // no diagnostic
}

-- sub/tagged.go --
//go:build go1.22

package sub

import "go/types"

func _() {
	// old package-level type
	var _ types.Info

	// new field of older type
	_ = new(types.Info).FileVersions

	// new method of older type
	_ = new(types.Info).PkgNameOf

	// new package-level type
	var a types.Alias

	// new method of new type
	a.Underlying()
}



================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/stdversion_synctest.txt
================================================
This test verifies that "too new" diagnostics from the stdversion analyzer
are suppressed for synctest when the go version is go1.24 or later.
See golang/go#75367

Set max to go1.25 since the synctest experiment was removed in go1.26.

-- env --
GOEXPERIMENT=synctest
-- flags --
-min_go_command=go1.24
-max_go_command=go1.25

-- go.mod --
module example.com

go 1.24

-- a/a.go --
//go:build goexperiment.synctest || go1.25
package a

import "testing/synctest"

func _() {
	synctest.Wait() // no diagnostic, see golang/go#75367
}


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/strangefiles.txt
================================================
This test checks diagnostics on files that are strange for one reason or
another.

Note(rfindley): ported from the old marker tests. I'm not sure why these were
written originally.

-ignore_extra_diags is required because the marker framework fails for
noparse.go, and we therefore can't match the EOF error.

-- flags --
-ignore_extra_diags
-errors_ok

-- go.mod --
module golang.org/lsptests

go 1.18
-- %percent/perc%ent.go --
package percent //@diag("percent", re"No packages")

-- noparse/noparse.go --



================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/typeerr.txt
================================================

This test exercises diagnostics produced for type errors
in the absence of syntax errors.

The type error was chosen to exercise the 'nonewvars' type-error analyzer.
(The 'undeclaredname' analyzer depends on the text of the go/types
"undeclared name" error, which changed in go1.20.)

The append() type error was also carefully chosen to have text and
position that are invariant across all versions of Go run by the builders.

-- go.mod --
module example.com
go 1.12

-- typeerr.go --
package a

func f(x int) {
	append("") //@diag(re`""`, re"a slice")

	x := 123 //@diag(re"x := 123", re"no new variables"), quickfix(re"():", re"no new variables", fix)
}

-- @fix/typeerr.go --
@@ -6 +6 @@
-	x := 123 //@diag(re"x := 123", re"no new variables"), quickfix(re"():", re"no new variables", fix)
+	x = 123 //@diag(re"x := 123", re"no new variables"), quickfix(re"():", re"no new variables", fix)


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/useinternal.txt
================================================
This test checks a diagnostic for invalid use of internal packages.

This list error changed in Go 1.21.

See TestValidImportCheck_GoPackagesDriver for a test that no diagnostic
is produced when using a GOPACKAGESDRIVER (such as for Bazel).

-- go.mod --
module bad.test

go 1.18

-- assign/internal/secret/secret.go --
package secret

func Hello() {}

-- bad/bad.go --
package bad

import _ "bad.test/assign/internal/secret" //@diag("\"bad.test/assign/internal/secret\"", re"could not import bad.test/assign/internal/secret \\(invalid use of internal package \"bad.test/assign/internal/secret\"\\)"),diag("_", re"use of internal package bad.test/assign/internal/secret not allowed")


================================================
FILE: gopls/internal/test/marker/testdata/diagnostics/usemodule.txt
================================================
This test demonstrates diagnostics for a module that is missing from the
go.work file.

Quick-fixes change files on disk, so are tested by integration tests.

-- skip --
Temporary skip due to golang/go#57979, with zero-config gopls, these modules
are no longer orphaned.

-- go.work --
go 1.21

use (
	./a
)

-- a/go.mod --
module mod.com/a

go 1.18

-- a/main.go --
package main

import "mod.com/a/lib"

func main() {
	_ = lib.C
}

-- a/lib/lib.go --
package lib

const C = "b"
-- b/go.mod --
module mod.com/b

go 1.18

-- b/main.go --
package main //@diag("main", re"add this module to your go.work")

import "mod.com/b/lib" //@diag("\"mod.com", re"not included in a workspace module")

func main() {
	_ = lib.C
}

-- b/lib/lib.go --
package lib //@diag("lib", re"add this module to your go.work")

const C = "b"


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue59318.txt
================================================
Previously, this test verifies that we can load multiple orphaned files as
command-line-arguments packages. In the distant past, we would load only one
because go/packages returns at most one command-line-arguments package per
query.

With zero-config gopls, these packages are successfully loaded as ad-hoc
packages.

-- a/main.go --
package main

func main() {
	var a int //@diag(re"var (a)", re"not used")
}
-- b/main.go --
package main

func main() {
	var b int //@diag(re"var (b)", re"not used")
}


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue59944.txt
================================================
This test verifies that gopls does not panic when encountering the go/types
bug described in golang/go#59944: the Bindingf function is not included in
the methodset of its receiver type.

Adapted from the code in question from the issue.

The flag -ignore_extra_diags is included, as this bug was fixed in Go 1.24, so
that now the code below may produce a diagnostic.

-- flags --
-cgo
-ignore_extra_diags

-- go.mod --
module example.com

go 1.12

-- cgo.go --
package x

import "fmt"

/*
struct layout {
	int field;
};
*/
import "C"

type Layout = C.struct_layout

// Bindingf is a printf wrapper. This was necessary to trigger the panic in
// objectpath while encoding facts.
func (l *Layout) Bindingf(format string, args ...any) {
	fmt.Printf(format, args...)
}


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue61543.txt
================================================
This test verifies that we fail loudly if a module name contains
command-line-arguments.

-- flags --
-errors_ok

-- go.mod --
module command-line-arguments //@diag("module", re`command-line-arguments.*disallowed`)

go 1.12

-- x/x.go --
package x //@diag("x", re`command-line-arguments.*disallowed`)


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue66109.txt
================================================
This test exercises the crash in golang/go#66109: a dangling reference due to
test variants of a command-line-arguments package.

Depends on go1.22+ go list errors.

-- flags --
-min_go_command=go1.22

-- go.mod --
module example.com/tools

go 1.22

-- tools_test.go --
//go:build tools

package tools //@diag("tools", re"No packages found")

import (
	_ "example.com/tools/tool"
)

-- tool/tool.go --
package main

func main() {
}


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue66250.txt
================================================
This bug checks the fix for golang/go#66250. Package references should not
crash when one package file lacks a package name.

TODO(rfindley): the -ignore_extra_diags flag is only necessary because of
problems matching diagnostics in the broken file, likely due to poor parser
recovery.

-- flags --
-ignore_extra_diags

-- a.go --
package x //@refs("x", "x")

-- b.go --

func _() {
}


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue66876.txt
================================================
This test checks that gopls successfully suppresses loopclosure diagnostics
when the go.mod go version is set to a 1.22 toolchain version (1.22.x).

In golang/go#66876, gopls failed to handle this correctly.

-- flags --
-min_go_command=go1.22

-- go.mod --
module example.com/loopclosure

go 1.22.0

-- p.go --
package main

var x int //@loc(x, "x")

func main() {
	// Verify that type checking actually succeeded by jumping to
	// an arbitrary definition.
	_ = x //@def("x", x)

	for i := range 10 {
		go func() { println(i) }()
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue71044.txt
================================================
This test checks that we don't crash while completing receivers that may happen
to be builtin types (due to invalid code). This crash was reported by telemetry
in golang/go#71044.

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com/amap

go 1.18

-- a.go --
package amap

import "unsafe"

func (unsafe.Pointer) _() {} //@ rank(re"()unsafe")


================================================
FILE: gopls/internal/test/marker/testdata/fixedbugs/issue74581.txt
================================================
This test checks that gopls does not panic when requesting code actions
for an import that fails to resolve a package name (such as renaming "C").

-- flags --
-cgo

-- go.mod --
module example.com

go 1.18

-- a.go --
package p //@ diag(re"^", re`cannot rename import "C"`), diag(re"^", re"go list failed")

import . "C" //@ codeaction(".", "refactor.rewrite.eliminateDotImport", err="found 0 CodeActions"), diag(re`[.]`, re`cannot rename import "C"`)



================================================
FILE: gopls/internal/test/marker/testdata/foldingrange/a.txt
================================================
This test checks basic behavior of textDocument/foldingRange.

-- a.go --
package folding //@foldingrange(raw)

import (
	"fmt"
	_ "log"
	"sort"
	"time"
)

import _ "os"

// Bar is a function.
// With a multiline doc comment.
func Bar() (
	string,
) {
	/* This is a single line comment */
	switch {
	case true:
		if true {
			fmt.Println("true")
		} else {
			fmt.Println("false")
		}
	case false:
		fmt.Println("false")
	default:
		fmt.Println("default")
	}
	/* This is a multiline
	block
	comment */

	/* This is a multiline
	block
	comment */
	// Followed by another comment.
	_ = []int{
		1,
		2,
		3,
	}
	_ = [2]string{"d",
		"e",
	}
	_ = map[string]int{
		"a": 1,
		"b": 2,
		"c": 3,
	}
	type T struct {
		f string
		g int
		h string
	}
	_ = T{
		f: "j",
		g: 4,
		h: "i",
	}
	x, y := make(chan bool), make(chan bool)
	select {
	case val := <-x:
		if val {
			fmt.Println("true from x")
		} else {
			fmt.Println("false from x")
		}
	case <-y:
		fmt.Println("y")
	default:
		fmt.Println("default")
	}
	// This is a multiline comment
	// that is not a doc comment.
	return `
this string
is not indented`
}

func _() {
	slice := []int{1, 2, 3}
	sort.Slice(slice, func(i, j int) bool {
		a, b := slice[i], slice[j]
		return a > b
	})

	sort.Slice(slice, func(i, j int) bool { return slice[i] > slice[j] })

	sort.Slice(
		slice,
		func(i, j int) bool {
			return slice[i] > slice[j]
		},
	)

	fmt.Println(
		1, 2, 3,
		4,
	)

	fmt.Println(1, 2, 3,
		4, 5, 6,
		7, 8, 9,
		10)

	// Call with ellipsis.
	_ = fmt.Errorf(
		"test %d %d",
		[]any{1, 2, 3}...,
	)

	// Check multiline string.
	fmt.Println(
		`multi
		line
		string
		`,
		1, 2, 3,
	)

	// Call without arguments.
	_ = time.Now()
}

func _(
	a int, b int,
	c int,
) {
}

func _() { // comment

}

-- @raw --
package folding //@foldingrange(raw)

import (<0 kind="imports">
	"fmt"
	_ "log"
	"sort"
	"time"
</0>)

import _ "os"

// Bar is a function.<1 kind="comment">
// With a multiline doc comment.</1>
func Bar() (<2 kind="">
	string,
</2>) {<3 kind="">
	/* This is a single line comment */
	switch {<4 kind="">
	case true:<5 kind="">
		if true {<6 kind="">
			fmt.Println(<7 kind="">"true"</7>)
		</6>} else {<8 kind="">
			fmt.Println(<9 kind="">"false"</9>)
		</8>}</5>
	case false:<10 kind="">
		fmt.Println(<11 kind="">"false"</11>)</10>
	default:<12 kind="">
		fmt.Println(<13 kind="">"default"</13>)</12>
	</4>}
	/* This is a multiline<14 kind="comment">
	block
	comment */</14>

	/* This is a multiline<15 kind="comment">
	block
	comment */
	// Followed by another comment.</15>
	_ = []int{<16 kind="">
		1,
		2,
		3,
	</16>}
	_ = [2]string{<17 kind="">"d",
		"e",
	</17>}
	_ = map[string]int{<18 kind="">
		"a": 1,
		"b": 2,
		"c": 3,
	</18>}
	type T struct {<19 kind="">
		f string
		g int
		h string
	</19>}
	_ = T{<20 kind="">
		f: "j",
		g: 4,
		h: "i",
	</20>}
	x, y := make(<21 kind="">chan bool</21>), make(<22 kind="">chan bool</22>)
	select {<23 kind="">
	case val := <-x:<24 kind="">
		if val {<25 kind="">
			fmt.Println(<26 kind="">"true from x"</26>)
		</25>} else {<27 kind="">
			fmt.Println(<28 kind="">"false from x"</28>)
		</27>}</24>
	case <-y:<29 kind="">
		fmt.Println(<30 kind="">"y"</30>)</29>
	default:<31 kind="">
		fmt.Println(<32 kind="">"default"</32>)</31>
	</23>}
	// This is a multiline comment<33 kind="comment">
	// that is not a doc comment.</33>
	return <34 kind="">`
this string
is not indented`</34>
</3>}

func _() {<35 kind="">
	slice := []int{<36 kind="">1, 2, 3</36>}
	sort.Slice(<37 kind="">slice, func(<38 kind="">i, j int</38>) bool {<39 kind="">
		a, b := slice[i], slice[j]
		return a > b
	</39>}</37>)

	sort.Slice(<40 kind="">slice, func(<41 kind="">i, j int</41>) bool {<42 kind=""> return slice[i] > slice[j] </42>}</40>)

	sort.Slice(<43 kind="">
		slice,
		func(<44 kind="">i, j int</44>) bool {<45 kind="">
			return slice[i] > slice[j]
		</45>},
	</43>)

	fmt.Println(<46 kind="">
		1, 2, 3,
		4,
	</46>)

	fmt.Println(<47 kind="">1, 2, 3,
		4, 5, 6,
		7, 8, 9,
		10</47>)

	// Call with ellipsis.
	_ = fmt.Errorf(<48 kind="">
		"test %d %d",
		[]any{<49 kind="">1, 2, 3</49>}...,
	</48>)

	// Check multiline string.
	fmt.Println(<50 kind="">
		<51 kind="">`multi
		line
		string
		`</51>,
		1, 2, 3,
	</50>)

	// Call without arguments.
	_ = time.Now()
</35>}

func _(<52 kind="">
	a int, b int,
	c int,
</52>) {<53 kind="">
</53>}

func _() {<54 kind=""> // comment

</54>}



================================================
FILE: gopls/internal/test/marker/testdata/foldingrange/a_lineonly.txt
================================================
This test checks basic behavior of the textDocument/foldingRange, when the
editor only supports line folding.

-- capabilities.json --
{
	"textDocument": {
		"foldingRange": {
			"lineFoldingOnly": true
		}
	}
}
-- a.go --
package folding //@foldingrange(raw)

import (
	"fmt"
	_ "log"
	"sort"
	"time"
)

import _ "os"

// Bar is a function.
// With a multiline doc comment.
func Bar() string {
	/* This is a single line comment */
	switch {
	case true:
		if true {
			fmt.Println("true")
		} else {
			fmt.Println("false")
		}
	case false:
		fmt.Println("false")
	default:
		fmt.Println("default")
	}
	/* This is a multiline
	block
	comment */

	/* This is a multiline
	block
	comment */
	// Followed by another comment.
	_ = []int{
		1,
		2,
		3,
	}
	_ = [2]string{"d",
		"e",
	}
	_ = map[string]int{
		"a": 1,
		"b": 2,
		"c": 3,
	}
	type T struct {
		f string
		g int
		h string
	}
	_ = T{
		f: "j",
		g: 4,
		h: "i",
	}
	x, y := make(chan bool), make(chan bool)
	select {
	case val := <-x:
		if val {
			fmt.Println("true from x")
		} else {
			fmt.Println("false from x")
		}
	case <-y:
		fmt.Println("y")
	default:
		fmt.Println("default")
	}
	// This is a multiline comment
	// that is not a doc comment.
	return `
this string
is not indented`
}

func _() {
	slice := []int{1, 2, 3}
	sort.Slice(slice, func(i, j int) bool {
		a, b := slice[i], slice[j]
		return a > b
	})

	sort.Slice(slice, func(i, j int) bool { return slice[i] > slice[j] })

	sort.Slice(
		slice,
		func(i, j int) bool {
			return slice[i] > slice[j]
		},
	)

	fmt.Println(
		1, 2, 3,
		4,
	)

	fmt.Println(1, 2, 3,
		4, 5, 6,
		7, 8, 9,
		10)

	// Call with ellipsis.
	_ = fmt.Errorf(
		"test %d %d",
		[]any{1, 2, 3}...,
	)

	// Check multiline string.
	fmt.Println(
		`multi
		line
		string
		`,
		1, 2, 3,
	)

	// Call without arguments.
	_ = time.Now()
}

func _(
	a int, b int,
	c int,
) {
}
-- @raw --
package folding //@foldingrange(raw)

import (<0 kind="imports">
	"fmt"
	_ "log"
	"sort"
	"time"</0>
)

import _ "os"

// Bar is a function.<1 kind="comment">
// With a multiline doc comment.</1>
func Bar() string {<2 kind="">
	/* This is a single line comment */
	switch {<3 kind="">
	case true:<4 kind="">
		if true {<5 kind="">
			fmt.Println("true")</5>
		} else {<6 kind="">
			fmt.Println("false")</6>
		}</4>
	case false:<7 kind="">
		fmt.Println("false")</7>
	default:<8 kind="">
		fmt.Println("default")</3></8>
	}
	/* This is a multiline<9 kind="comment">
	block
	comment */</9>

	/* This is a multiline<10 kind="comment">
	block
	comment */
	// Followed by another comment.</10>
	_ = []int{<11 kind="">
		1,
		2,
		3,</11>
	}
	_ = [2]string{<12 kind="">"d",
		"e",</12>
	}
	_ = map[string]int{<13 kind="">
		"a": 1,
		"b": 2,
		"c": 3,</13>
	}
	type T struct {<14 kind="">
		f string
		g int
		h string</14>
	}
	_ = T{<15 kind="">
		f: "j",
		g: 4,
		h: "i",</15>
	}
	x, y := make(chan bool), make(chan bool)
	select {<16 kind="">
	case val := <-x:<17 kind="">
		if val {<18 kind="">
			fmt.Println("true from x")</18>
		} else {<19 kind="">
			fmt.Println("false from x")</19>
		}</17>
	case <-y:<20 kind="">
		fmt.Println("y")</20>
	default:<21 kind="">
		fmt.Println("default")</16></21>
	}
	// This is a multiline comment<22 kind="comment">
	// that is not a doc comment.</22>
	return <23 kind="">`
this string
is not indented`</2></23>
}

func _() {<24 kind="">
	slice := []int{1, 2, 3}
	sort.Slice(<25 kind="">slice, func(i, j int) bool {<26 kind="">
		a, b := slice[i], slice[j]
		return a > b</25></26>
	})

	sort.Slice(slice, func(i, j int) bool { return slice[i] > slice[j] })

	sort.Slice(<27 kind="">
		slice,
		func(i, j int) bool {<28 kind="">
			return slice[i] > slice[j]</28>
		},</27>
	)

	fmt.Println(<29 kind="">
		1, 2, 3,
		4,</29>
	)

	fmt.Println(<30 kind="">1, 2, 3,
		4, 5, 6,
		7, 8, 9,</30>
		10)

	// Call with ellipsis.
	_ = fmt.Errorf(<31 kind="">
		"test %d %d",
		[]any{1, 2, 3}...,</31>
	)

	// Check multiline string.
	fmt.Println(<32 kind="">
		<33 kind="">`multi
		line
		string
		`</33>,
		1, 2, 3,</32>
	)

	// Call without arguments.
	_ = time.Now()</24>
}

func _(<34 kind="">
	a int, b int,
	c int,</34>
) {
}


================================================
FILE: gopls/internal/test/marker/testdata/foldingrange/bad.txt
================================================
This test verifies behavior of textDocument/foldingRange in the presence of
unformatted syntax.

-- a.go --
package folding //@foldingrange(raw)

import ( "fmt"
	_ "log"
)

import ( 
	_ "os" )
	
// BadBar is a function.
func BadBar() string { x := true
	if x { 
		// This is the only foldable thing in this file when lineFoldingOnly
		fmt.Println("true")
	} else {
		fmt.Println("false") }
	return ""
}
-- @raw --
package folding //@foldingrange(raw)

import (<0 kind="imports"> "fmt"
	_ "log"
</0>)

import (<1 kind="imports"> 
	_ "os" </1>)
	
// BadBar is a function.
func BadBar() string {<2 kind=""> x := true
	if x {<3 kind=""> 
		// This is the only foldable thing in this file when lineFoldingOnly
		fmt.Println(<4 kind="">"true"</4>)
	</3>} else {<5 kind="">
		fmt.Println(<6 kind="">"false"</6>) </5>}
	return ""
</2>}


================================================
FILE: gopls/internal/test/marker/testdata/foldingrange/parse_errors.txt
================================================
This test verifies that textDocument/foldingRange does not panic
and produces no folding ranges if a file contains errors.

-- flags --
-ignore_extra_diags

-- a.go --
package folding //@foldingrange(raw)

// No comma.
func _(
	a string
) {}

// Extra brace.
func _() {}}
-- @raw --
package folding //@foldingrange(raw)

// No comma.
func _(
	a string
) {}

// Extra brace.
func _() {}}


================================================
FILE: gopls/internal/test/marker/testdata/format/format.txt
================================================
This test checks basic behavior of textDocument/formatting requests.

-- go.mod --
module mod.com

go 1.18
-- good.go --
package format //@format(good)

import (
	"log"
)

func goodbye() {
	log.Printf("byeeeee")
}

-- @good --
package format //@format(good)

import (
	"log"
)

func goodbye() {
	log.Printf("byeeeee")
}
-- bad.go --
package format //@format(bad)

import (
	"runtime"
	"fmt"
	"log"
)

func hello() {




	var x int //@diag("x", re"declared (and|but) not used")
}

func hi() {
	runtime.NumCPU()
	fmt.Printf("")

	log.Printf("")
}
-- @bad --
package format //@format(bad)

import (
	"fmt"
	"log"
	"runtime"
)

func hello() {

	var x int //@diag("x", re"declared (and|but) not used")
}

func hi() {
	runtime.NumCPU()
	fmt.Printf("")

	log.Printf("")
}
-- newline.go --
package format //@format(newline)
func _() {}
-- @newline --
package format //@format(newline)
func _()       {}
-- oneline.go --
package format //@format(oneline)
-- @oneline --
package format //@format(oneline)


================================================
FILE: gopls/internal/test/marker/testdata/format/generated.txt
================================================
This test checks that formatting includes generated files too
(reversing https://go.dev/cl/365295 to address issue #49555).

See https://github.com/golang/go/issues/73959.

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com
go 1.21

-- a/a.go --
// Code generated by me. DO NOT EDIT.

package a; import "fmt"; func main() { fmt.Println("hello") }

//@format(out)

-- @out --
// Code generated by me. DO NOT EDIT.

package a

import "fmt"

func main() { fmt.Println("hello") }

//@format(out)


================================================
FILE: gopls/internal/test/marker/testdata/format/issue59554.txt
================================================
Test case for golang/go#59554: data corruption on formatting due to line
directives.

Note that gofumpt is needed for this test case, as it reformats var decls into
short var decls.

-- settings.json --
{
	"formatting.gofumpt": true
}

-- main.go --
package main //@format(main)

func Match(data []byte) int {
//line :1
	var idx = ^uint(0)
	_ = idx
	return -1
}
-- @main --
package main //@format(main)

func Match(data []byte) int {
//line :1
	idx := ^uint(0)
	_ = idx
	return -1
}


================================================
FILE: gopls/internal/test/marker/testdata/format/noparse.txt
================================================
This test checks that formatting does not run on code that has parse errors.

-- parse.go --
package noparse_format //@format(parse)

func _() {
f() //@diag("f", re"(undefined|undeclared name): f")
}
-- @parse --
package noparse_format //@format(parse)

func _() {
	f() //@diag("f", re"(undefined|undeclared name): f")
}
-- noparse.go --
package noparse_format //@format(noparse)

// The nonewvars expectation asserts that the go/analysis framework ran.

func what() {
	var hi func()
	if {		hi() //@diag(re"(){", re".*missing.*")
	}
	hi := nil
}
-- @noparse --
7:5: missing condition in if statement


================================================
FILE: gopls/internal/test/marker/testdata/highlight/controlflow.txt
================================================
This test verifies document highlighting for control flow.

-- go.mod --
module mod.com

go 1.18

-- p.go --
package p

-- issue60589.go --
package p

// This test verifies that control flow highlighting correctly
// accounts for multi-name result parameters.
// In golang/go#60589, it did not.

func _() (foo int, bar, baz string) { //@ hiloc(func, "func", text), hiloc(foo, "foo", text), hiloc(fooint, "foo int", text), hiloc(int, "int", text), hiloc(bar, "bar", text), hiloc(beforebaz, " baz", text), hiloc(baz, "baz", text), hiloc(barbazstring, "bar, baz string", text), hiloc(beforestring, re`() string`, text), hiloc(string, "string", text)
	return 0, "1", "2" //@ hiloc(return, `return 0, "1", "2"`, text), hiloc(l0, "0", text), hiloc(l1, `"1"`, text), hiloc(l2, `"2"`, text)
}

// Assertions, expressed here to avoid clutter above.
// Note that when the cursor is over the field type, there is some
// (likely harmless) redundancy.

//@ highlight(func, func, return)
//@ highlight(foo, foo, l0)
//@ highlight(int, fooint, int, l0)
//@ highlight(bar, bar, l1)
//@ highlight(beforebaz)
//@ highlight(baz, baz, l2)
//@ highlight(beforestring, baz, l2)
//@ highlight(string, barbazstring, string, l1, l2)
//@ highlight(l0, foo, l0)
//@ highlight(l1, bar, l1)
//@ highlight(l2, baz, l2)

// Check that duplicate result names do not cause
// inaccurate highlighting.

func _() (x, x int32) { //@ loc(locx1, re`\((x)`), loc(locx2, re`(x) int`), hiloc(x1, re`\((x)`, text), hiloc(x2, re`(x) int`, text), diag(locx1, re"redeclared"), diag(locx2, re"redeclared")
	return 1, 2 //@ hiloc(one, "1", text), hiloc(two, "2", text)
}

//@ highlight(one, one, x1)
//@ highlight(two, two, x2)
//@ highlight(x1, x1, one)
//@ highlight(x2, x2, two)

-- issue65516.go --
package p

// This test checks that gopls doesn't crash while highlighting
// functions with no body (golang/go#65516).

func Foo() (int, string) //@hiloc(noBodyInt, "int", text), hiloc(noBodyFunc, "func", text)
//@highlight(noBodyInt, noBodyInt), highlight(noBodyFunc, noBodyFunc)

-- issue65952.go --
package p

// This test checks  that gopls doesn't crash while highlighting
// return values in functions with no results.

func _() {
	return 0 //@hiloc(ret1, "0", text), diag("0", re"too many return")
	//@highlight(ret1, ret1)
}

func _() () {
	return 0 //@hiloc(ret2, "0", text), diag("0", re"too many return")
	//@highlight(ret2, ret2)
}


================================================
FILE: gopls/internal/test/marker/testdata/highlight/highlight.txt
================================================
This test checks basic functionality of the textDocument/highlight request.

-- highlights.go --
package highlights

import (
	"fmt"         //@hiloc(fmtImp, "\"fmt\"", text),highlightall(fmtImp, fmt1, fmt2, fmt3, fmt4)
	h2 "net/http" //@hiloc(hImp, "h2", text),highlightall(hImp, hUse)
	"sort"
)

type F struct{ bar int } //@hiloc(barDeclaration, "bar", text),highlightall(barDeclaration, bar1, bar2, bar3)

func _() F {
	return F{
		bar: 123, //@hiloc(bar1, "bar", write)
	}
}

var foo = F{bar: 52} //@hiloc(fooDeclaration, "foo", write),hiloc(bar2, "bar", write),highlightall(fooDeclaration, fooUse)

func Print() { //@hiloc(printFunc, "Print", text),highlightall(printFunc, printTest)
	_ = h2.Client{} //@hiloc(hUse, "h2", text)

	fmt.Println(foo) //@hiloc(fooUse, "foo", read),hiloc(fmt1, "fmt", text)
	fmt.Print("yo")  //@hiloc(printSep, "Print", text),highlightall(printSep, print1, print2),hiloc(fmt2, "fmt", text)
}

func (x *F) Inc() { //@hiloc(xRightDecl, "x", text),hiloc(xLeftDecl, " *", text),highlightall(xRightDecl, xUse),highlight(xLeftDecl, xRightDecl, xUse)
	x.bar++ //@hiloc(xUse, "x", read),hiloc(bar3, "bar", write)
}

func testFunctions() {
	fmt.Print("main start") //@hiloc(print1, "Print", text),hiloc(fmt3, "fmt", text)
	fmt.Print("ok")         //@hiloc(print2, "Print", text),hiloc(fmt4, "fmt", text)
	Print()                 //@hiloc(printTest, "Print", text)
}

// DocumentHighlight is undefined, so its uses below are type errors.
// Nevertheless, document highlighting should still work.
//@diag(locdoc1, re"undefined|undeclared"), diag(locdoc2, re"undefined|undeclared"), diag(locdoc3, re"undefined|undeclared")

func toProtocolHighlight(rngs []int) []DocumentHighlight { //@loc(locdoc1, "DocumentHighlight"), hiloc(doc1, "DocumentHighlight", text),hiloc(docRet1, "[]DocumentHighlight", text),highlight(doc1, docRet1, doc1, doc2, doc3, result)
	result := make([]DocumentHighlight, 0, len(rngs)) //@loc(locdoc2, "DocumentHighlight"), hiloc(doc2, "DocumentHighlight", text),highlight(doc2, doc1, doc2, doc3)
	for _, rng := range rngs {
		result = append(result, DocumentHighlight{ //@loc(locdoc3, "DocumentHighlight"), hiloc(doc3, "DocumentHighlight", text),highlight(doc3, doc1, doc2, doc3)
			Range: rng,
		})
	}
	return result //@hiloc(result, "result", text)
}

func testForLoops() {
	for i := 0; i < 10; i++ { //@hiloc(forDecl1, "for", text),highlightall(forDecl1, brk1, cont1)
		if i > 8 {
			break //@hiloc(brk1, "break", text)
		}
		if i < 2 {
			for j := 1; j < 10; j++ { //@hiloc(forDecl2, "for", text),highlightall(forDecl2, cont2)
				if j < 3 {
					for k := 1; k < 10; k++ { //@hiloc(forDecl3, "for", text),highlightall(forDecl3, cont3)
						if k < 3 {
							continue //@hiloc(cont3, "continue", text)
						}
					}
					continue //@hiloc(cont2, "continue", text)
				}
			}
			continue //@hiloc(cont1, "continue", text)
		}
	}

	arr := []int{}
	for i := range arr { //@hiloc(forDecl4, "for", text),highlightall(forDecl4, brk4, cont4)
		if i > 8 {
			break //@hiloc(brk4, "break", text)
		}
		if i < 4 {
			continue //@hiloc(cont4, "continue", text)
		}
	}

Outer:
	for i := 0; i < 10; i++ { //@hiloc(forDecl5, "for", text),highlightall(forDecl5, brk5, brk6, brk8)
		break //@hiloc(brk5, "break", text)
		for { //@hiloc(forDecl6, "for", text),highlightall(forDecl6, cont5), diag("for", re"unreachable")
			if i == 1 {
				break Outer //@hiloc(brk6, "break Outer", text)
			}
			switch i { //@hiloc(switch1, "switch", text),highlightall(switch1, brk7)
			case 5:
				break //@hiloc(brk7, "break", text)
			case 6:
				continue //@hiloc(cont5, "continue", text)
			case 7:
				break Outer //@hiloc(brk8, "break Outer", text)
			}
		}
	}
}

func testSwitch() {
	var i, j int

L1:
	for { //@hiloc(forDecl7, "for", text),highlightall(forDecl7, brk10, cont6)
	L2:
		switch i { //@hiloc(switch2, "switch", text),highlightall(switch2, brk11, brk12, brk13)
		case 1:
			switch j { //@hiloc(switch3, "switch", text),highlightall(switch3, brk9)
			case 1:
				break //@hiloc(brk9, "break", text)
			case 2:
				break L1 //@hiloc(brk10, "break L1", text)
			case 3:
				break L2 //@hiloc(brk11, "break L2", text)
			default:
				continue //@hiloc(cont6, "continue", text)
			}
		case 2:
			break //@hiloc(brk12, "break", text)
		default:
			break L2 //@hiloc(brk13, "break L2", text)
		}
	}
}

func testReturn() bool { //@hiloc(func1, "func", text),hiloc(bool1, "bool", text),highlight(func1, func1, fullRet11, fullRet12),highlight(bool1, bool1, false1, bool2, true1)
	if 1 < 2 {
		return false //@hiloc(ret11, "return", text),hiloc(fullRet11, "return false", text),hiloc(false1, "false", text),highlight(ret11, func1, fullRet11, fullRet12)
	}
	candidates := []int{}
	sort.SliceStable(candidates, func(i, j int) bool { //@hiloc(func2, "func", text),hiloc(bool2, "bool", text),highlight(func2, func2, fullRet2)
		return candidates[i] > candidates[j] //@hiloc(ret2, "return", text),hiloc(fullRet2, "return candidates[i] > candidates[j]", text),highlight(ret2, func2, fullRet2)
	})
	return true //@hiloc(ret12, "return", text),hiloc(fullRet12, "return true", text),hiloc(true1, "true", text),highlight(ret12, func1, fullRet11, fullRet12)
}

func testReturnFields() float64 { //@hiloc(retVal1, "float64", text),highlight(retVal1, retVal1, retVal11, retVal21)
	if 1 < 2 {
		return 20.1 //@hiloc(retVal11, "20.1", text),highlight(retVal11, retVal1, retVal11, retVal21)
	}
	z := 4.3 //@hiloc(zDecl, "z", write)
	return z //@hiloc(retVal21, "z", text),highlight(retVal21, retVal1, retVal11, zDecl, retVal21)
}

func testReturnMultipleFields() (float32, string) { //@hiloc(retVal31, "float32", text),hiloc(retVal32, "string", text),highlight(retVal31, retVal31, retVal41, retVal51),highlight(retVal32, retVal32, retVal42, retVal52)
	y := "im a var" //@hiloc(yDecl, "y", write),
	if 1 < 2 {
		return 20.1, y //@hiloc(retVal41, "20.1", text),hiloc(retVal42, "y", text),highlight(retVal41, retVal31, retVal41, retVal51),highlight(retVal42, retVal32, yDecl, retVal42, retVal52)
	}
	return 4.9, "test" //@hiloc(retVal51, "4.9", text),hiloc(retVal52, "\"test\"", text),highlight(retVal51, retVal31, retVal41, retVal51),highlight(retVal52, retVal32, retVal42, retVal52)
}

func testReturnFunc() int32 { //@hiloc(retCall, "int32", text)
	mulch := 1          //@hiloc(mulchDec, "mulch", write),highlight(mulchDec, mulchDec, mulchRet)
	return int32(mulch) //@hiloc(mulchRet, "mulch", read),hiloc(retFunc, "int32", text),hiloc(retTotal, "int32(mulch)", text),highlight(mulchRet, mulchDec, mulchRet),highlight(retFunc, retCall, retFunc, retTotal)
}


================================================
FILE: gopls/internal/test/marker/testdata/highlight/highlight_kind.txt
================================================
This test checks textDocument/highlight with highlight kinds.
For example, a use of a variable is reported as a "read",
and an assignment to a variable is reported as a "write".
(Note that the details don't align exactly with the Go
type-checker notions of values versus addressable variables).


-- highlight_kind.go --
package a

type Nest struct {
	nest *Nest //@hiloc(fNest, "nest", text)
}
type MyMap map[string]string

type NestMap map[Nest]Nest

func _() {
	const constIdent = 1 //@hiloc(constIdent, "constIdent", write)
	//@highlightall(constIdent)
	var varNoInit int    //@hiloc(varNoInit, "varNoInit", write)
	(varNoInit) = 1      //@hiloc(varNoInitAssign, "varNoInit", write)
	_ = varNoInit        //@hiloc(varNoInitRead, "varNoInit", read)
	//@highlightall(varNoInit, varNoInitAssign, varNoInitRead)

	str, num := "hello", 2 //@hiloc(str, "str", write), hiloc(num, "num", write)
	_, _ = str, num        //@hiloc(strRead, "str", read), hiloc(numRead, "num", read)
	//@highlightall(str, strRead, strMapKey, strMapVal, strMyMapKey, strMyMapVal, strMyMapSliceKey, strMyMapSliceVal, strMyMapPtrSliceKey, strMyMapPtrSliceVal)
	//@highlightall(num, numRead, numAddr, numIncr, numMul)
	nest := &Nest{nest: nil} //@hiloc(nest, "nest", write),hiloc(fNestComp, re`(nest):`, write)
	nest.nest = &Nest{}      //@hiloc(nestSelX, "nest", read), hiloc(fNestSel, re`(nest) =`, write)
	*nest.nest = Nest{}      //@hiloc(nestSelXStar, "nest", read), hiloc(fNestSelStar, re`(nest) =`, write)
	//@highlightall(nest, nestSelX, nestSelXStar, nestMapVal)
	//@highlightall(fNest, fNestComp, fNestSel, fNestSelStar, fNestSliceComp, fNestPtrSliceComp, fNestMapKey)

	pInt := &num //@hiloc(pInt, "pInt", write),hiloc(numAddr, "num", read)
	// StarExpr is reported as "write" in GoLand and Rust Analyzer
	*pInt = 3               //@hiloc(pIntStar, "pInt", write)
	var ppInt **int = &pInt //@hiloc(ppInt, "ppInt", write),hiloc(pIntAddr, re`&(pInt)`, read)
	**ppInt = 4             //@hiloc(ppIntStar, "ppInt", write)
	*(*ppInt) = 4           //@hiloc(ppIntParen, "ppInt", write)
	//@highlightall(pInt, pIntStar, pIntAddr)
	//@highlightall(ppInt, ppIntStar, ppIntParen)

	num++    //@hiloc(numIncr, "num", write)
	num *= 1 //@hiloc(numMul, "num", write)

	var ch chan int = make(chan int, 10) //@hiloc(ch, "ch", write)
	ch <- 3                              //@hiloc(chSend, "ch", write)
	<-ch                                 //@hiloc(chRecv, "ch", read)
	//@highlightall(ch, chSend, chRecv)

	var nums []int = []int{1, 2} //@hiloc(nums, "nums", write)
	// IndexExpr is reported as "read" in GoLand, Rust Analyzer and Java JDT
	nums[0] = 1 //@hiloc(numsIndex, "nums", read)
	//@highlightall(nums, numsIndex)

	mapLiteral := map[string]string{ //@hiloc(mapLiteral, "mapLiteral", write)
		str: str, //@hiloc(strMapKey, "str", read),hiloc(strMapVal, re`(str),`, read)
	}
	for key, value := range mapLiteral { //@hiloc(mapKey, "key", write), hiloc(mapVal, "value", write), hiloc(mapLiteralRange, "mapLiteral", read)
		_, _ = key, value //@hiloc(mapKeyRead, "key", read), hiloc(mapValRead, "value", read)
	}
	//@highlightall(mapLiteral, mapLiteralRange)
	//@highlightall(mapKey, mapKeyRead)
	//@highlightall(mapVal, mapValRead)

	nestSlice := []Nest{
		{nest: nil}, //@hiloc(fNestSliceComp, "nest", write)
	}
	nestPtrSlice := []*Nest{
		{nest: nil}, //@hiloc(fNestPtrSliceComp, "nest", write)
	}
	myMap := MyMap{
		str: str, //@hiloc(strMyMapKey, "str", read),hiloc(strMyMapVal, re`(str),`, read)
	}
	myMapSlice := []MyMap{
		{str: str}, //@hiloc(strMyMapSliceKey, "str", read),hiloc(strMyMapSliceVal, re`: (str)`, read)
	}
	myMapPtrSlice := []*MyMap{
		{str: str}, //@hiloc(strMyMapPtrSliceKey, "str", read),hiloc(strMyMapPtrSliceVal, re`: (str)`, read)
	}
	nestMap := NestMap{
		Nest{nest: nil}: *nest, //@hiloc(fNestMapKey, "nest", write), hiloc(nestMapVal, re`(nest),`, read)
	}

	_, _, _, _, _, _ = myMap, nestSlice, nestPtrSlice, myMapSlice, myMapPtrSlice, nestMap
}


================================================
FILE: gopls/internal/test/marker/testdata/highlight/highlight_printf.txt
================================================

This test checks functionality of the printf-like directives and operands highlight.
-- flags --
-ignore_extra_diags
-- highlights.go --
package highlightprintf
import (
	"fmt"
)

func BasicPrintfHighlights() {
	fmt.Printf("Hello %s, you have %d new messages!", "Alice", 5) //@hiloc(normals, "%s", write),hiloc(normalarg0, "\"Alice\"", read),highlightall(normals, normalarg0)
	fmt.Printf("Hello %s, you have %d new messages!", "Alice", 5) //@hiloc(normald, "%d", write),hiloc(normalargs1, "5", read),highlightall(normald, normalargs1)
}

func ComplexPrintfHighlights() {
	fmt.Printf("Hello %#3.4s, you have %-2.3d new messages!", "Alice", 5) //@hiloc(complexs, "%#3.4s", write),hiloc(complexarg0, "\"Alice\"", read),highlightall(complexs, complexarg0)
	fmt.Printf("Hello %#3.4s, you have %-2.3d new messages!", "Alice", 5) //@hiloc(complexd, "%-2.3d", write),hiloc(complexarg1, "5", read),highlightall(complexd, complexarg1)
}

func MissingDirectives() {
	fmt.Printf("Hello %s, you have 5 new messages!", "Alice", 5) //@hiloc(missings, "%s", write),hiloc(missingargs0, "\"Alice\"", read),highlightall(missings, missingargs0)
}

func TooManyDirectives() {
	fmt.Printf("Hello %s, you have %d new %s %q messages!", "Alice", 5) //@hiloc(toomanys, "%s", write),hiloc(toomanyargs0, "\"Alice\"", read),highlightall(toomanys, toomanyargs0)
	fmt.Printf("Hello %s, you have %d new %s %q messages!", "Alice", 5) //@hiloc(toomanyd, "%d", write),hiloc(toomanyargs1, "5", read),highlightall(toomanyd, toomanyargs1)
}

func VerbIsPercentage() {
	fmt.Printf("%4.2% %d", 6) //@hiloc(z1, "%d", write),hiloc(z2, "6", read),highlightall(z1, z2)
}

func SpecialChars() {
	fmt.Printf("Hello \n %s, you \t \n have %d new messages!", "Alice", 5) //@hiloc(specials, "%s", write),hiloc(specialargs0, "\"Alice\"", read),highlightall(specials, specialargs0)
	fmt.Printf("Hello \n %s, you \t \n have %d new messages!", "Alice", 5) //@hiloc(speciald, "%d", write),hiloc(specialargs1, "5", read),highlightall(speciald, specialargs1)
}

func Escaped() {
	fmt.Printf("Hello %% \n %s, you \t%% \n have %d new m%%essages!", "Alice", 5) //@hiloc(escapeds, "%s", write),hiloc(escapedargs0, "\"Alice\"", read),highlightall(escapeds, escapedargs0)
	fmt.Printf("Hello %% \n %s, you \t%% \n have %d new m%%essages!", "Alice", 5) //@hiloc(escapedd, "%s", write),hiloc(escapedargs1, "\"Alice\"", read),highlightall(escapedd, escapedargs1)
	fmt.Printf("%d \nss \x25[2]d", 234, 123) //@hiloc(zz1, "%d", write),hiloc(zz2, "234", read),highlightall(zz1,zz2)
	fmt.Printf("%d \nss \x25[2]d", 234, 123) //@hiloc(zz3, "\\x25[2]d", write),hiloc(zz4, "123", read),highlightall(zz3,zz4)
}

func Indexed() {
	fmt.Printf("%[1]d", 3) //@hiloc(i1, "%[1]d", write),hiloc(i2, "3", read),highlightall(i1, i2)
	fmt.Printf("%[1]*d", 3, 6) //@hiloc(i3, "[1]*", write),hiloc(i4, "3", read),hiloc(i5, "d", write),hiloc(i6, "6", read),highlightall(i3, i4),highlightall(i5, i6)
	fmt.Printf("%[2]*[1]d", 3, 4) //@hiloc(i7, "[2]*", write),hiloc(i8, "4", read),hiloc(i9, "[1]d", write),hiloc(i10, "3", read),highlightall(i7, i8),highlightall(i9, i10)
	fmt.Printf("%[2]*.[1]*[3]d", 4, 5, 6) //@hiloc(i11, "[2]*", write),hiloc(i12, "5", read),hiloc(i13, ".[1]*", write),hiloc(i14, "4", read),hiloc(i15, "[3]d", write),hiloc(i16, "6", read),highlightall(i11, i12),highlightall(i13, i14),highlightall(i15, i16)
}

func MultipleIndexed() {
	fmt.Printf("%[1]d %[1].2d", 3) //@hiloc(m1, "%[1]d", write),hiloc(m2, "3", read),hiloc(m3, "%[1].2d", write),highlightall(m1, m2, m3)
}

// This test checks that gopls doesn't crash (index out of bounds)
// while haven't fill the last non-variadic argument.
func NoEffectOnUnfinishedArg() {
	var s string //@hiloc(var, "s", write)
	fmt.Fprintf(s) //@hiloc(firstArg, "s", read),highlightall(var, firstArg)
}


================================================
FILE: gopls/internal/test/marker/testdata/highlight/issue60435.txt
================================================
This is a regression test for issue 60435:
Highlighting "net/http" shouldn't have any effect
on an import path that contains it as a substring,
such as httptest.

-- highlights.go --
package highlights

import (
	"net/http"          //@hiloc(httpImp, `"net/http"`, text)
	"net/http/httptest" //@hiloc(httptestImp, `"net/http/httptest"`, text)
)

var _ = httptest.NewRequest
var _ = http.NewRequest //@hiloc(here, "http", text), highlight(here, here, httpImp)


================================================
FILE: gopls/internal/test/marker/testdata/highlight/issue68918.txt
================================================
Regression test for https://github.com/golang/go/issues/68918:
crash due to missing type information in CompositeLit.

The corresponding go/types fix in Go 1.24 introduces a
new error message, hence the -ignore_extra_diags flag.

-- flags --
-ignore_extra_diags

-- a.go --
package a

var _ = T{{ x }} //@hiloc(x, "x", text), diag("T", re"undefined"), diag("{ ", re"missing type")

//@highlight(x, x)


================================================
FILE: gopls/internal/test/marker/testdata/highlight/switchbreak.txt
================================================
This is a regression test for issue 65752: a break in a switch should
highlight the switch, not the enclosing loop.

We suppress staticheck since it also gives a diagnostic
about the break being ineffective.

-- settings.json --
{
	"staticcheck": false
}

-- a.go --
package a

func _(x any) {
	for {
		// type switch
		switch x.(type) { //@hiloc(tswitch, "switch", text)
		default:
			break //@hiloc(tbreak, "break", text),highlight(tbreak, tswitch, tbreak)
		}

		// value switch
		switch { //@hiloc(vswitch, "switch", text)
		default:
			break //@hiloc(vbreak, "break", text), highlight(vbreak, vswitch, vbreak)
		}
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/hover/basiclit.txt
================================================
This test checks gopls behavior when hovering over basic literals.

Skipped on ppc64 as there appears to be a bug on aix-ppc64: golang/go#67526.

-- flags --
-skip_goarch=ppc64

-- basiclit.go --
package basiclit

func _() {
	_ = 'a' //@hover("'a'", "'a'", latinA)
	_ = 0x61 //@hover("0x61", "0x61", latinAHex)

	_ = '\u2211' //@hover("'\\u2211'", "'\\u2211'", summation)
	_ = '\u2211' //@hover(re"u22()11", "'\\u2211'", summation)
	_ = 0x2211 //@hover("0x2211", "0x2211", summationHex)
	_ = "foo \u2211 bar" //@hover("\\u2211", "\\u2211", summation)

	_ = '\a' //@hover("'\\a'", "'\\a'", control)
	_ = "foo \a bar" //@hover("\\a", "\\a", control)

	_ = '\U0001F30A' //@hover("'\\U0001F30A'", "'\\U0001F30A'", waterWave)
	_ = 0x0001F30A //@hover("0x0001F30A", "0x0001F30A", waterWaveHex)
	_ = 0X0001F30A //@hover("0X0001F30A", "0X0001F30A", waterWaveHex)
	_ = "foo \U0001F30A bar" //@hover("\\U0001F30A", "\\U0001F30A", waterWave)

	_ = '\x7E' //@hover("'\\x7E'", "'\\x7E'", tilde)
	_ = "foo \x7E bar" //@hover("\\x7E", "\\x7E", tilde)
	_ = "foo \a bar" //@hover("\\a", "\\a", control)

	_ = '\173' //@hover("'\\173'", "'\\173'", leftCurly)
	_ = "foo \173 bar" //@hover("\\173","\\173", leftCurly)
	_ = "foo \173 bar \u2211 baz" //@hover("\\173","\\173", leftCurly)
	_ = "foo \173 bar \u2211 baz" //@hover("\\u2211","\\u2211", summation)
	_ = "foo\173bar\u2211baz" //@hover("\\173","\\173", leftCurly)
	_ = "foo\173bar\u2211baz" //@hover("\\u2211","\\u2211", summation)

	// incorrect position
	_ = "foo\173bar\u2211baz" //@hover("az",_,_)

	// search for runes in string only if there is an escaped sequence
	_ = "hello" //@hover(`"hello"`, _, _)

	// incorrect escaped rune sequences
	_ = '\0' //@hover("'\\0'", _, _),diag(re`\\0()'`, re"illegal character")
	_ = '\u22111' //@hover("'\\u22111'", _, _)
	_ = '\U00110000' //@hover("'\\U00110000'", _, _)
	_ = '\u12e45'//@hover("'\\u12e45'", _, _)
	_ = '\xa' //@hover("'\\xa'", _, _)
	_ = 'aa' //@hover("'aa'", _, _)

	// other basic lits
	_ = 1 //@hover("1", _, _)
	_ = 1.2 //@hover("1.2", _, _)
	_ = 1.2i //@hover("1.2i", _, _)
	_ = 0123 //@hover("0123", _, _)
	_ = 0b1001 //@hover("0b", "0b1001", binaryNumber)
	_ = 0B1001 //@hover("0B", "0B1001", binaryNumber)
	_ = 0o77 //@hover("0o", "0o77", octalNumber)
	_ = 0O77 //@hover("0O", "0O77", octalNumber)
	_ = 0x1234567890 //@hover("0x1234567890", "0x1234567890", hexNumber)
	_ = 0X1234567890 //@hover("0X1234567890", "0X1234567890", hexNumber)
	_ = 0x1000000000000000000 //@hover("0x1", "0x1000000000000000000", bigHex)
}
-- @bigHex --
4722366482869645213696
-- @binaryNumber --
9
-- @control --
U+0007, control
-- @hexNumber --
78187493520
-- @latinA --
'a', U+0061, LATIN SMALL LETTER A
-- @latinAHex --
97, 'a', U+0061, LATIN SMALL LETTER A
-- @leftCurly --
'{', U+007B, LEFT CURLY BRACKET
-- @octalNumber --
63
-- @summation --
'∑', U+2211, N-ARY SUMMATION
-- @summationHex --
8721, '∑', U+2211, N-ARY SUMMATION
-- @tilde --
'~', U+007E, TILDE
-- @waterWave --
'🌊', U+1F30A, WATER WAVE
-- @waterWaveHex --
127754, '🌊', U+1F30A, WATER WAVE


================================================
FILE: gopls/internal/test/marker/testdata/hover/comment.txt
================================================
This test checks hovering over doc links in comments.

-- go.mod --
module mod.com

go 1.20

-- a.go --
package p

import (
	"unsafe"

	"mod.com/util" //@hover(`"mod.com/util"`, `"mod.com/util"`, strconv)
)

// [NumberBase] is the base to use for number parsing. //@hover("NumberBase", "NumberBase", NumberBase),hover(re"()NumberBase", "NumberBase", NumberBase),hover(re"NumberBase()", "NumberBase", NumberBase)
const NumberBase = 10

// [Conv] converts s to an int. //@hover("Conv", "Conv", Conv)
func Conv(s string) int {
	// [util.ParseInt] parses s and returns the integer corresponding to it. //@hover("util", "util", util),hover("ParseInt", "ParseInt", strconvParseInt)
	// [NumberBase] is the base to use for number parsing.
	i, _ := util.ParseInt(s, NumberBase, 64)
	return int(i)
}

// UnsafeConv converts s to a byte slice using [unsafe.Pointer]. hover("Pointer", "Pointer", unsafePointer)
func UnsafeConv(s string) []byte {
	p := unsafe.StringData(s)
	b := unsafe.Slice(p, len(s))
	return b
}

-- util/conv.go --
// Package util provides utility functions.
package util

import "strconv"

// ParseInt interprets a string s in the given base (0, 2 to 36) and
// bit size (0 to 64) and returns the corresponding value i.
func ParseInt(s string, base int, bitSize int) (int64, error) {
	return strconv.ParseInt(s, base, bitSize)
}

-- @Conv --
```go
func Conv(s string) int
```

---

[Conv](file://$WORKDIR/a.go#13,6) converts s to an int. //@hover("Conv", "Conv", Conv)


---

[`p.Conv` on pkg.go.dev](https://pkg.go.dev/mod.com#Conv)
-- @NumberBase --
```go
const NumberBase untyped int = 10
```

---

[NumberBase](file://$WORKDIR/a.go#10,7) is the base to use for number parsing. //@hover("NumberBase", "NumberBase", NumberBase),hover(re"()NumberBase", "NumberBase", NumberBase),hover(re"NumberBase()", "NumberBase", NumberBase)


---

[`p.NumberBase` on pkg.go.dev](https://pkg.go.dev/mod.com#NumberBase)
-- @strconv --
```go
package util
```

---

Package util provides utility functions.
-- @strconvParseInt --
```go
func ParseInt(s string, base int, bitSize int) (int64, error)
```

---

ParseInt interprets a string s in the given base (0, 2 to 36) and bit size (0 to 64) and returns the corresponding value i.


---

[`util.ParseInt` on pkg.go.dev](https://pkg.go.dev/mod.com/util#ParseInt)
-- @util --
```go
package util
```

---

Package util provides utility functions.


================================================
FILE: gopls/internal/test/marker/testdata/hover/const.txt
================================================
This test checks hovering over constants.

-- go.mod --
module mod.com

go 1.17

-- c.go --
package c

import (
	"math"
	"time"
)

const X = 0 //@hover("X", "X", bX)

// dur is a constant of type time.Duration.
const dur = 15*time.Minute + 10*time.Second + 350*time.Millisecond //@hover("dur", "dur", dur)

const _ = dur // pacify unusedfunc

// MaxFloat32 is used in another package.
const MaxFloat32 = 0x1p127 * (1 + (1 - 0x1p-23))

// Numbers.
func _() {
	const hex, bin = 0xe34e, 0b1001001

	const (
		// no inline comment
		decimal = 153

		numberWithUnderscore int64 = 10_000_000_000
		octal                      = 0o777
		expr                       = 2 << (0b111&0b101 - 2)
		boolean                    = (55 - 3) == (26 * 2)
	)

	_ = decimal              //@hover("decimal", "decimal", decimalConst)
	_ = hex                  //@hover("hex", "hex", hexConst)
	_ = bin                  //@hover("bin", "bin", binConst)
	_ = numberWithUnderscore //@hover("numberWithUnderscore", "numberWithUnderscore", numberWithUnderscoreConst)
	_ = octal                //@hover("octal", "octal", octalConst)
	_ = expr                 //@hover("expr", "expr", exprConst)
	_ = boolean              //@hover("boolean", "boolean", boolConst)

	const ln10 = 2.30258509299404568401799145468436420760110148862877297603332790

	_ = ln10 //@hover("ln10", "ln10", ln10Const)
}

// Iota.
func _() {
	const (
		a = 1 << iota
		b
	)

	_ = a //@hover("a", "a", aIota)
	_ = b //@hover("b", "b", bIota)
}

// Strings.
func _() {
	const (
		str     = "hello" + " " + "world"
		longStr = `Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur eget ipsum non nunc
molestie mattis id quis augue. Mauris dictum tincidunt ipsum, in auctor arcu congue eu.
Morbi hendrerit fringilla libero commodo varius. Vestibulum in enim rutrum, rutrum tellus
aliquet, luctus enim. Nunc sem ex, consectetur id porta nec, placerat vel urna.`
	)

	_ = str     //@hover("str", "str", strConst)
	_ = longStr //@hover("longStr", "longStr", longStrConst)
}

// Constants from other packages.
func _() {
	_ = math.Log2E //@hover("Log2E", "Log2E", log2eConst)
}

-- @bX --
```go
const X untyped int = 0
```

---

@hover("X", "X", bX)


---

[`c.X` on pkg.go.dev](https://pkg.go.dev/mod.com#X)
-- @dur --
```go
const dur time.Duration = 15*time.Minute + 10*time.Second + 350*time.Millisecond // 15m10.35s
```

---

dur is a constant of type time.Duration.
-- @decimalConst --
```go
const decimal untyped int = 153
```

---

no inline comment
-- @hexConst --
```go
const hex untyped int = 0xe34e // 58190
```
-- @binConst --
```go
const bin untyped int = 0b1001001 // 73
```
-- @numberWithUnderscoreConst --
```go
const numberWithUnderscore int64 = 10_000_000_000 // 10000000000
```
-- @octalConst --
```go
const octal untyped int = 0o777 // 511
```
-- @exprConst --
```go
const expr untyped int = 2 << (0b111&0b101 - 2) // 16
```
-- @boolConst --
```go
const boolean untyped bool = (55 - 3) == (26 * 2) // true
```
-- @ln10Const --
```go
const ln10 untyped float = 2.30258509299404568401799145468436420760110148862877297603332790 // 2.30259
```
-- @aIota --
```go
const a untyped int = 1 << iota // 1
```
-- @bIota --
```go
const b untyped int = 2
```
-- @strConst --
```go
const str untyped string = "hello world"
```
-- @longStrConst --
```go
const longStr untyped string = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur e...
```
-- @log2eConst --
```go
const math.Log2E untyped float = 1 / Ln2 // 1.4427
```

---

Mathematical constants.


---

[`math.Log2E` on pkg.go.dev](https://pkg.go.dev/math#Log2E)


================================================
FILE: gopls/internal/test/marker/testdata/hover/embed.txt
================================================
This test checks that hover reports accessible embedded fields
(after the doc comment  and before the accessible methods).

-- go.mod --
module example.com

go 1.18

-- q/q.go --
package q

type Q struct {
	One int
	two string
	q2[chan int]
}

type q2[T any] struct {
	Three *T
	four string
}

-- p.go --
package p

import "example.com/q"

// doc
type P struct {
	q.Q
}

func (P) m() {}

var p P //@hover("P", "P", P)

var _, _ = P.m, p // pacify unusedfunc

type A struct {
	*B
}

type B struct {
	*C
}

type C struct {
	*D
}

type D struct {
	E int
}

type X struct{
	*Y
}

type Y struct {
	*Z
}

type Z struct{
	z int
}

var a A
var _ = a.E //@hover("E", "E", E)

var x struct {
	*X
}
var _ = x.z //@hover("z", "z", Z)

type Al2 = int
type N struct{
	x Al2
	y struct{ ZA }
}
type Al = *N
type S struct{ Al }
type ZA = *Z
var _ = new(S).x //@hover("x", "x", X)
var _ = new(S).y.z //@hover("z", "z", Zz), hover("y", "y", y)

-- @P --
```go
type P struct {
	q.Q
}
```

---

doc


```go
// Embedded fields:
One   int       // through Q    
Three *chan int // through Q.q2 
```

```go
func (P) m()
```

---

[`p.P` on pkg.go.dev](https://pkg.go.dev/example.com#P)
-- @E --
```go
field E int // through *B, *C, *D
```

---

[`(p.D).E` on pkg.go.dev](https://pkg.go.dev/example.com#D.E)
-- @Z --
```go
field z int // through *X, *Y, *Z
```
-- @X --
```go
field x Al2 // through Al
```
-- @Zz --
```go
field z int // through ZA
```
-- @y --
```go
field y struct{ZA} // through Al
```


================================================
FILE: gopls/internal/test/marker/testdata/hover/expression.txt
================================================
This test checks that hovering over a range reveals the expression type.

-- a.go --
package a

import "time"

const (
    _ = 'a' + 2//@hover("'a' + 2", "'a' + 2", "99")

    _ = "A" + "B"//@hover("\"A\" + \"B\"", "\"A\" + \"B\"", "AB")

    _ = 2 * 3 * 4//@hover("3 * 4", "2 * 3 * 4", "24")

    _ = (1 < 2)//@hover("1 < 2", "1 < 2", "true")

    _ = (1 + 2i) * (3 + 4i)//@hover("(1 + 2i) * (3 + 4i)", "(1 + 2i) * (3 + 4i)", "(-5 + 10i)")
)

type Foo struct {
    foo string
}

func _() {
    // type of slice expression.
    ints := []int{}
    _ = ints[1:2]//@hover("ints[1:2]", "ints[1:2]", "[]int")

    foos := []Foo{}
    _ = foos[1:2]//@hover("foos[1:2]", "foos[1:2]", "[]Foo")

    // type of map expression
    m := map[string]int{"one": 1}
    _ = m["one"]//@hover("m[\"one\"]", "m[\"one\"]", "int")

    // type of channel expression
    ch := make(chan bool)
    _ = <-ch//@hover("<-ch", "<-ch", "bool")

    // type of pointer expression
    ptr := &ch//@hover("&ch", "&ch", "*chan bool")
    _ = *ptr//@hover("*ptr", "*ptr", "chan bool")

    // type of unary
    _ = -ints[0]//@hover("-ints[0]", "-ints[0]", "int")

    // type of type assertion
    var x any

    _ = x.(*Foo)//@hover("x.(*Foo)", "x.(*Foo)", "*Foo"),diag(re"x.()", re"nil dereference in type assertion")

    // Expression inside of switch statement does not have a type. 
    switch x := x.(type) {//@hover("x.(type)",_, _)
    default:
        _ = x
    }

    // type of function/method return value.
    _ = time.Now().UTC().Add(10 * time.Minute)//@hover("time.Now().UTC()", "time.Now().UTC()", "time.Time")

    // type of function/method signature.
    _ = time.Now().UTC().Add(10 * time.Minute)//@hover("time.Now().UTC", "time.Now().UTC", "func() time.Time")

    // type of field
    var t time.Timer
    _ = <-t.C//@hover("t.C", "t.C", "<-chan time.Time"),hover("<-t.C", "<-t.C", "time.Time")
}


================================================
FILE: gopls/internal/test/marker/testdata/hover/fileuri.txt
================================================
This test demonstrates file uri over doc link in hover.

-- settings.json --
{
	"hoverKind": "FullDocumentation"
}

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com

go 1.18

-- main.go --
package main

import (
    "example.com/foo"
)

func main() {
    // Call [foo.Foo]//@hover("Foo", "Foo", Foo)
    foo.Foo()//@hover("Foo", "Foo", fooFoo)
}

-- foo/foo.go --
// package foo defines function [Foo]//@hover("Foo", "Foo", Foo)
package foo

import(
    "example.com/a"
    "example.com/b"
)

// doc comment for Foo will reference the following
//
// two packages [a] and [b]
//
// a type [a.A]
//
// a type's field [a.A.A]
//
// a type's method [a.A.Bar]
//
// an interface [a.I]
//
// an interface's method [a.I.Foo]
//
// a const [b.B]
//
// a variable [b.V]
//
// a doc link [xtools github website]
//
// [xtools github website]: https://github.com/golang/tools
func Foo() {} //@hover("Foo", "Foo", Foo)
-- a/a.go --
package a

type A struct {
    A string
}

func (*A) Bar(){}

type I interface {
    Foo()
}

-- b/b.go --
package b

import (
    "example.com/a"
)

const B = 3

var V = 4
-- @Foo --
```go
func Foo()
```

---

doc comment for Foo will reference the following

two packages [a](file://$WORKDIR/foo/foo.go#5,5) and [b](file://$WORKDIR/foo/foo.go#6,5)

a type [a.A](file://$WORKDIR/a/a.go#3,6)

a type's field [a.A.A](file://$WORKDIR/a/a.go#4,5)

a type's method [a.A.Bar](file://$WORKDIR/a/a.go#7,11)

an interface [a.I](file://$WORKDIR/a/a.go#9,6)

an interface's method [a.I.Foo](file://$WORKDIR/a/a.go#10,5)

a const [b.B](file://$WORKDIR/b/b.go#7,7)

a variable [b.V](file://$WORKDIR/b/b.go#9,5)

a doc link [xtools github website](https://github.com/golang/tools)


---

[`foo.Foo` on pkg.go.dev](https://pkg.go.dev/example.com/foo#Foo)
-- @fooFoo --
```go
func foo.Foo()
```

---

doc comment for Foo will reference the following

two packages [a](file://$WORKDIR/foo/foo.go#5,5) and [b](file://$WORKDIR/foo/foo.go#6,5)

a type [a.A](file://$WORKDIR/a/a.go#3,6)

a type's field [a.A.A](file://$WORKDIR/a/a.go#4,5)

a type's method [a.A.Bar](file://$WORKDIR/a/a.go#7,11)

an interface [a.I](file://$WORKDIR/a/a.go#9,6)

an interface's method [a.I.Foo](file://$WORKDIR/a/a.go#10,5)

a const [b.B](file://$WORKDIR/b/b.go#7,7)

a variable [b.V](file://$WORKDIR/b/b.go#9,5)

a doc link [xtools github website](https://github.com/golang/tools)


---

[`foo.Foo` on pkg.go.dev](https://pkg.go.dev/example.com/foo#Foo)


================================================
FILE: gopls/internal/test/marker/testdata/hover/generics.txt
================================================
This file contains tests for hovering over generic Go code.

Requires go1.20+ for the new go/doc/comment package, and a change in Go 1.20
that affected the formatting of constraint interfaces.

Its size expectations assume a 64-bit machine.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- flags --
-skip_goarch=386,arm

-- go.mod --
// A go.mod is require for correct pkgsite links.
// TODO(rfindley): don't link to ad-hoc or command-line-arguments packages!
module mod.com

go 1.18

-- issue68213.go --
package generics

// Hovering over an interface with empty type set must not panic.
type empty interface { //@hover("empty", "empty", empty)
	int
	string
}

-- @empty --
```go
type empty interface { // size=16 (0x10)
	int
	string
}
```

---

Hovering over an interface with empty type set must not panic.
-- generics.go --
package generics

type value[T any] struct { //@hover("lue", "value", value),hover("T", "T", valueT)
	val T   //@hover("T", "T", valuevalT)
	Q   int64 //@hover("Q", "Q", valueQ)
}

type Value[T any] struct { //@hover("T", "T", ValueT)
	val T   //@hover("T", "T", ValuevalT)
	Q   int64 //@hover("Q", "Q", ValueQ)
}

func F[P interface{ ~int | string }]() { //@hover("P", "P", Ptparam)
	var _ P //@hover("P","P",Pvar)
}

-- @value --
```go
type value[T any] struct {
	val T     //@hover("T", "T", valuevalT)
	Q   int64 //@hover("Q", "Q", valueQ)
}
```
-- @valueT --
```go
type parameter T any
```
-- @valuevalT --
```go
type parameter T any
```
-- @valueQ --
```go
field Q int64 // size=8
```

---

@hover("Q", "Q", valueQ)
-- @ValueT --
```go
type parameter T any
```
-- @ValuevalT --
```go
type parameter T any
```
-- @ValueQ --
```go
field Q int64 // size=8
```

---

@hover("Q", "Q", ValueQ)


---

[`(generics.Value).Q` on pkg.go.dev](https://pkg.go.dev/mod.com#Value.Q)
-- @Ptparam --
```go
type parameter P interface{~int | string}
```
-- @Pvar --
```go
type parameter P interface{~int | string}
```
-- inferred.go --
package generics

func app[S interface{ ~[]E }, E any](s S, e E) S {
	return append(s, e)
}

func _() {
	_ = app[[]int]             //@hover("app", "app", appint)
	_ = app[[]int, int]        //@hover("app", "app", appint)
	_ = app[[]int]([]int{}, 0) //@hover("app", "app", appint), diag("[[]int]", re"unnecessary")
	_ = app([]int{}, 0)        //@hover("app", "app", appint)
}

-- @appint --
```go
func app(s []int, e int) []int // func[S interface{~[]E}, E any](s S, e E) S
```


================================================
FILE: gopls/internal/test/marker/testdata/hover/godef.txt
================================================
This test was ported from 'godef' in the old marker tests.
It tests various hover and definition requests.

-- go.mod --
module godef.test

go 1.18

-- a/a_x_test.go --
package a_test

import (
	"testing"
)

func TestA2(t *testing.T) { //@hover("TestA2", "TestA2", TestA2)
	Nonexistant() //@diag("Nonexistant", re"(undeclared name|undefined): Nonexistant")
}

-- @TestA2 --
```go
func TestA2(t *testing.T)
```
-- @ember --
```go
field Member string
```

---

@loc(Member, "Member")


---

[`(a.Thing).Member` on pkg.go.dev](https://pkg.go.dev/godef.test/a#Thing.Member)
-- a/d.go --
package a //@hover("a", _, a)

import "fmt"

type Thing struct { //@loc(Thing, "Thing")
	Member string //@loc(Member, "Member")
}

var Other Thing //@loc(Other, "Other")

func Things(val []string) []Thing { //@loc(Things, "Things")
	return nil
}

func (t Thing) Method(i int) string { //@loc(Method, "Method")
	return t.Member
}

func (t Thing) Method3() {
}

func (t *Thing) Method2(i int, j int) (error, string) {
	return nil, t.Member
}

func (t *Thing) private() {
}

func useThings() {
	t := Thing{ //@hover("ing", "Thing", ing)
		Member: "string", //@hover("ember", "Member", ember), def("ember", Member)
	}
	fmt.Print(t.Member) //@hover("ember", "Member", ember), def("ember", Member)
	fmt.Print(Other)    //@hover("ther", "Other", ther), def("ther", Other)
	Things(nil)         //@hover("ings", "Things", ings), def("ings", Things)
	t.Method(0)         //@hover("eth", "Method", eth), def("eth", Method)
}

type NextThing struct { //@loc(NextThing, "NextThing")
	Thing
	Value int
}

func (n NextThing) another() string {
	return n.Member
}

// Shadows Thing.Method3
func (n *NextThing) Method3() int {
	return n.Value
}

var nextThing NextThing //@hover("NextThing", "NextThing", NextThing), def("NextThing", NextThing)

-- @ings --
```go
func Things(val []string) []Thing
```

---

[`a.Things` on pkg.go.dev](https://pkg.go.dev/godef.test/a#Things)
-- @ther --
```go
var Other Thing
```

---

@loc(Other, "Other")


---

[`a.Other` on pkg.go.dev](https://pkg.go.dev/godef.test/a#Other)
-- @a --
-- @ing --
```go
type Thing struct {
	Member string //@loc(Member, "Member")
}
```

---

```go
func (t Thing) Method(i int) string
func (t *Thing) Method2(i int, j int) (error, string)
func (t Thing) Method3()
func (t *Thing) private()
```

---

[`a.Thing` on pkg.go.dev](https://pkg.go.dev/godef.test/a#Thing)
-- @NextThing --
```go
type NextThing struct {
	Thing
	Value int
}
```

---

```go
// Embedded fields:
Member string // through Thing 
```

```go
func (t Thing) Method(i int) string
func (t *Thing) Method2(i int, j int) (error, string)
func (n *NextThing) Method3() int
func (n NextThing) another() string
func (t *Thing) private()
```

---

[`a.NextThing` on pkg.go.dev](https://pkg.go.dev/godef.test/a#NextThing)
-- @eth --
```go
func (t Thing) Method(i int) string
```

---

[`(a.Thing).Method` on pkg.go.dev](https://pkg.go.dev/godef.test/a#Thing.Method)
-- a/f.go --
// Package a is a package for testing go to definition.
package a

import "fmt"

func TypeStuff() {
	var x string

	switch y := any(x).(type) { //@loc(y, "y"), hover("y", "y", y) , def("y", y)
	case int: //@loc(intY, "int")
		fmt.Printf("%v", y) //@hover("y", "y", inty), def("y", y)
	case string: //@loc(stringY, "string")
		fmt.Printf("%v", y) //@hover("y", "y", stringy), def("y", y)
	}

}
-- @inty --
```go
var y int
```
-- @stringy --
```go
var y string
```
-- @y --
```go
var y any
```
-- a/h.go --
package a

func _() {
	type s struct {
		nested struct {
			// nested number
			number int64 //@loc(nestedNumber, "number")
		}
		nested2 []struct {
			// nested string
			str string //@loc(nestedString, "str")
		}
		x struct {
			x struct {
				x struct {
					x struct {
						x struct {
							// nested map
							m map[string]float64 //@loc(nestedMap, "m")
						}
					}
				}
			}
		}
	}

	var t s
	_ = t.nested.number  //@hover("number", "number", nestedNumber), def("number", nestedNumber)
	_ = t.nested2[0].str //@hover("str", "str", nestedString), def("str", nestedString)
	_ = t.x.x.x.x.x.m    //@hover("m", "m", nestedMap), def("m", nestedMap)
}

func _() {
	var s struct {
		// a field
		a int //@loc(structA, "a")
		// b nested struct
		b struct { //@loc(structB, "b")
			// c field of nested struct
			c int //@loc(structC, "c")
		}
	}
	_ = s.a   //@def("a", structA)
	_ = s.b   //@def("b", structB)
	_ = s.b.c //@def("c", structC)

	var arr []struct {
		// d field
		d int //@loc(arrD, "d")
		// e nested struct
		e struct { //@loc(arrE, "e")
			// f field of nested struct
			f int //@loc(arrF, "f")
		}
	}
	_ = arr[0].d   //@def("d", arrD)
	_ = arr[0].e   //@def("e", arrE)
	_ = arr[0].e.f //@def("f", arrF)

	var complex []struct {
		c <-chan map[string][]struct {
			// h field
			h int //@loc(complexH, "h")
			// i nested struct
			i struct { //@loc(complexI, "i")
				// j field of nested struct
				j int //@loc(complexJ, "j")
			}
		}
	}
	_ = (<-complex[0].c)["0"][0].h   //@def("h", complexH)
	_ = (<-complex[0].c)["0"][0].i   //@def("i", complexI)
	_ = (<-complex[0].c)["0"][0].i.j //@def("j", complexJ)

	var mapWithStructKey map[struct { //@diag("struct", re"invalid map key")
		// X key field
		x []string //@loc(mapStructKeyX, "x")
	}]int
	for k := range mapWithStructKey {
		_ = k.x //@def("x", mapStructKeyX)
	}

	var mapWithStructKeyAndValue map[struct {
		// Y key field
		y string //@loc(mapStructKeyY, "y")
	}]struct {
		// X value field
		x string //@loc(mapStructValueX, "x")
	}
	for k, v := range mapWithStructKeyAndValue {
		// TODO: we don't show docs for y field because both map key and value
		// are structs. And in this case, we parse only map value
		_ = k.y //@hover("y", "y", hoverStructKeyY), def("y", mapStructKeyY)
		_ = v.x //@hover("x", "x", hoverStructKeyX), def("x", mapStructValueX)
	}

	var i []map[string]interface {
		// open method comment
		open() error //@loc(openMethod, "open")
	}
	i[0]["1"].open() //@hover("pen","open", openMethod), def("open", openMethod)
}

func _() {
	test := struct {
		// test description
		desc string //@loc(testDescription, "desc")
	}{}
	_ = test.desc //@def("desc", testDescription)

	for _, tt := range []struct {
		// test input
		in map[string][]struct { //@loc(testInput, "in")
			// test key
			key string //@loc(testInputKey, "key")
			// test value
			value any //@loc(testInputValue, "value")
		}
		result struct {
			v <-chan struct {
				// expected test value
				value int //@loc(testResultValue, "value")
			}
		}
	}{} {
		_ = tt.in               //@def("in", testInput)
		_ = tt.in["0"][0].key   //@def("key", testInputKey)
		_ = tt.in["0"][0].value //@def("value", testInputValue)

		_ = (<-tt.result.v).value //@def("value", testResultValue)
	}
}

func _() {
	getPoints := func() []struct {
		// X coord
		x int //@loc(returnX, "x")
		// Y coord
		y int //@loc(returnY, "y")
	} {
		return nil
	}

	r := getPoints()
	_ = r[0].x //@def("x", returnX)
	_ = r[0].y //@def("y", returnY)
}
-- @hoverStructKeyX --
```go
field x string
```

---

X value field
-- @hoverStructKeyY --
```go
field y string
```

---

Y key field
-- @nestedNumber --
```go
field number int64
```

---

nested number
-- @nestedString --
```go
field str string
```

---

nested string
-- @openMethod --
```go
func (interface) open() error
```

---

open method comment
-- @nestedMap --
```go
field m map[string]float64
```

---

nested map
-- b/e.go --
package b

import (
	"fmt"

	"godef.test/a"
)

func useThings() {
	t := a.Thing{}      //@loc(bStructType, "ing")
	fmt.Print(t.Member) //@loc(bMember, "ember")
	fmt.Print(a.Other)  //@loc(bVar, "ther")
	a.Things(nil)          //@loc(bFunc, "ings")
}

/*@
def(bStructType, Thing)
def(bMember, Member)
def(bVar, Other)
def(bFunc, Things)
*/

func _() {
	var x any
	switch x := x.(type) { //@hover("x", "x", xInterface)
	case string: //@loc(eString, "string")
		fmt.Println(x) //@hover("x", "x", xString)
	case int: //@loc(eInt, "int")
		fmt.Println(x) //@hover("x", "x", xInt)
	}
}
-- @xInt --
```go
var x int
```
-- @xInterface --
```go
var x any
```
-- @xString --
```go
var x string
```
-- broken/unclosedIf.go --
package broken

import "fmt"

func unclosedIf() {
	if false {
		var myUnclosedIf string              //@loc(myUnclosedIf, "myUnclosedIf")
		fmt.Printf("s = %v\n", myUnclosedIf) //@def("my", myUnclosedIf)
}

func _() {} //@diag("_", re"expected")


================================================
FILE: gopls/internal/test/marker/testdata/hover/goprivate.txt
================================================
This test checks that links in hover obey GOPRIVATE.

-- env --
GOPRIVATE=mod.com
-- go.mod --
module mod.com
-- p.go --
package p

// T should not be linked, as it is private.
type T struct{} //@hover("T", "T", T)
-- lib/lib.go --
package lib

// GOPRIVATE should also match nested packages.
type L struct{} //@hover("L", "L", L)
-- @L --
```go
type L struct{} // size=0
```

---

GOPRIVATE should also match nested packages.
-- @T --
```go
type T struct{} // size=0
```

---

T should not be linked, as it is private.


================================================
FILE: gopls/internal/test/marker/testdata/hover/hover-74351.txt
================================================
Regression test for crash in hover on an alias to a built-in named type.

-- flags --
-skip_goarch=386,arm

-- go.mod --
module example.com

go 1.18

-- a/a.go --
package a

type A = error //@hover("A", "A", out)

-- @out --
```go
type A = error // size=16 (0x10)

type error interface {
	Error() string
}
```

---

@hover("A", "A", out)


```go
func (error) Error() string
```

---

[`a.A` on pkg.go.dev](https://pkg.go.dev/example.com/a#A)


================================================
FILE: gopls/internal/test/marker/testdata/hover/hover.txt
================================================
This test demonstrates some basic features of hover.

One of those features is the display of per-file variation in
configuration, including GODEBUG. We use panicnil from go1.21 as an
arbitrary GODEBUG; if it goes away, pick another from
https://go.dev/doc/godebug#history.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- flags --
-min_go_command=go1.21

-- go.mod --
module example.com

go 1.18

-- a.go --
// package comment
package aa //@hover("aa", "aa", aa)

const abc = 0x2a //@hover("b", "abc", abc),hover(re"() =", "abc", abc)

-- a2.go --

//go:build go1.21

package aa //@hover("aa", "aa", aa2)

-- typeswitch.go --
package aa

func _() {
	var y any
	switch x := y.(type) { //@hover("x", "x", x)
	case int:
		println(x) //@hover("x", "x", xint)
	}
}
-- cmd/main.go --
//go:debug panicnil=0

// Note that since GODEBUG shows only settings that differ from
// the current toolchain, the output here depends on the toolchain used.
package main //@hover("main", "main", main)

func main() {
}

-- @abc --
```go
const abc untyped int = 0x2a // 42
```

---

@hover("b", "abc", abc),hover(re"() =", "abc", abc)
-- @x --
```go
var x any
```
-- @xint --
```go
var x int
```
-- @aa --
```go
package aa
```

---

package comment


---

 - Package path: example.com
 - Module: example.com
 - Language version: go1.18
-- @aa2 --
```go
package aa
```

---

package comment


---

 - Package path: example.com
 - Module: example.com
 - Language version (current file): go1.21
-- @main --
```go
package main
```

---

Note that since GODEBUG shows only settings that differ from the current toolchain, the output here depends on the toolchain used.


---

 - Package path: example.com/cmd
 - Module: example.com
 - Language version: go1.18


================================================
FILE: gopls/internal/test/marker/testdata/hover/hover_alias.txt
================================================
This test checks gopls behavior when hovering over alias type.

-- flags --
-skip_goarch=386,arm

-- go.mod --
module mod.com

go 1.18

-- main.go --
package main

import "mod.com/a"
import "mod.com/b"

type ToTypeDecl = b.RealType //@hover("ToTypeDecl", "ToTypeDecl", ToTypeDecl)

type ToAlias = a.Alias //@hover("ToAlias", "ToAlias", ToAlias)

type ToAliasWithComment = a.AliasWithComment //@hover("ToAliasWithComment", "ToAliasWithComment", ToAliasWithComment)

-- a/a.go --
package a
import "mod.com/b"

type Alias = b.RealType

// AliasWithComment is a type alias with comments.
type AliasWithComment = b.RealType

-- b/b.go --
package b
// RealType is a real type rather than an alias type.
type RealType struct {
	Name string
	Age int
}

-- generic/a.go --
package generic
func generic[T any]() {}

type Named string
type Alias = Named

func _(){
	generic[Alias]() //@hover("Alias", "Alias", Alias)
}

-- @ToTypeDecl --
```go
type ToTypeDecl = b.RealType // size=24 (0x18)

type RealType struct {
	Name string
	Age  int
}
```

---

@hover("ToTypeDecl", "ToTypeDecl", ToTypeDecl)


---

[`main.ToTypeDecl` on pkg.go.dev](https://pkg.go.dev/mod.com#ToTypeDecl)
-- @ToAlias --
```go
type ToAlias = a.Alias // size=24 (0x18)
```

---

@hover("ToAlias", "ToAlias", ToAlias)


---

[`main.ToAlias` on pkg.go.dev](https://pkg.go.dev/mod.com#ToAlias)
-- @ToAliasWithComment --
```go
type ToAliasWithComment = a.AliasWithComment // size=24 (0x18)
```

---

@hover("ToAliasWithComment", "ToAliasWithComment", ToAliasWithComment)


---

[`main.ToAliasWithComment` on pkg.go.dev](https://pkg.go.dev/mod.com#ToAliasWithComment)
-- @Alias --
```go
type Alias = Named

type Named string
```

---

[`generic.Alias` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#Alias)


================================================
FILE: gopls/internal/test/marker/testdata/hover/issue74361.txt
================================================
-- flags --
-skip_goarch=386,arm

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- go.mod --
module mod.com

-- a/a.go --
package a

type (
	Named  int
	Alias  = Named
	Alias2 = Alias
)

var (
	named  Named
	alias  Alias //@hover("alias", "alias", alias)
	alias2 Alias2 //@hover("alias2", "alias2", alias2)
)

-- @alias --
```go
var alias Alias
```

---

@hover("alias", "alias", alias)
-- @alias2 --
```go
var alias2 Alias2
```

---

@hover("alias2", "alias2", alias2)


================================================
FILE: gopls/internal/test/marker/testdata/hover/issue75975.txt
================================================
This test checks that hovering over an embedded field
reports information about the field, not its type.

We put backslash escapes in the hover expectation as the @hover marker
appears on the same line as the declaration. Otherwise the hover doc
content, which includes the comment containing the marker itself,
would trivially satisfy itself no matter what text we expect!

-- flags --
-skip_goarch=386,arm

-- go.mod --
module mod.com
go 1.18

-- a/a.go --
package a

type A struct {
	byte
	S string //@ hover("S", "S", "field S string // size=16 (0x10), offset=8\n")
}

type B struct {
	byte
	S //@ hover("S", "S", "field S S // size=1, class=8, offset=1\n")
}

type C struct {
	byte
	*S // hover("S", "S", "field S S // size=1, class=8, offset=1\n")
}

type S byte


================================================
FILE: gopls/internal/test/marker/testdata/hover/issues.txt
================================================
This test verifies fixes for various issues reported for hover.

-- go.mod --
module golang.org/lsptests

-- issue64239/p.go --
package issue64239

// golang/go#64239: hover fails for objects in the unsafe package.

import "unsafe"

var _ = unsafe.Sizeof(struct{}{}) //@hover("Sizeof", "Sizeof", "`Sizeof` on pkg.go.dev")

-- issue64237/p.go --
package issue64237

// golang/go#64237: hover panics for broken imports.

import "golang.org/lsptests/nonexistant" //@diag("\"golang", re"could not import")

var _ = nonexistant.Value //@hovererr("nonexistant", "no package data")

-- issue69362/p.go --
package issue69362

// golang/go#69362: hover panics over undefined implicits.

func _() {
	switch x := y.(type) { //@diag("y", re"undefined"), hover("x", "x", "")
	case int:
		_ = x
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/hover/json.txt
================================================
This test demonstrates support for "hoverKind": "Structured".

Its size expectations assume a 64-bit machine.

-- flags --
-skip_goarch=386,arm

-- go.mod --
module example.com/p

go 1.18

-- settings.json --
{
	"hoverKind": "Structured"
}
-- p.go --
package p

// MyType is a type.
type MyType struct { //@ hover("MyType", "MyType", MyType)
	F int // a field
	S string // a string field
}

// MyFunc is a function.
func MyFunc(i int) string { //@ hover("MyFunc", "MyFunc", MyFunc)
	return ""
}
-- @MyFunc --
{"synopsis":"MyFunc is a function.","fullDocumentation":"MyFunc is a function.\n","signature":"func MyFunc(i int) string","singleLine":"func MyFunc(i int) string","symbolName":"p.MyFunc","linkPath":"example.com/p","linkAnchor":"MyFunc"}
-- @MyType --
{"synopsis":"MyType is a type.","fullDocumentation":"MyType is a type.\n","signature":"type MyType struct { // size=24 (0x18)\n\tF int    // a field\n\tS string // a string field\n}\n","singleLine":"type MyType struct{F int; S string}","symbolName":"p.MyType","linkPath":"example.com/p","linkAnchor":"MyType"}


================================================
FILE: gopls/internal/test/marker/testdata/hover/linkable.txt
================================================
This test checks that we correctly determine pkgsite links for various
identifiers.

We should only produce links that work, meaning the object is reachable via the
package's public API.

-- go.mod --
module mod.com

go 1.18
-- p.go --
package p

type E struct {
	Embed int64
}

// T is in the package scope, and so should be linkable.
type T struct{ //@hover("T", "T", T)
	// Only exported fields should be linkable

	f int64 //@hover("f", "f", f)
	F int64 //@hover("F", "F", F)

	E

	// TODO(rfindley): is the link here correct? It ignores N.
	N struct {
		// Nested fields should also be linkable.
		Nested int64 //@hover("Nested", "Nested", Nested)
	}
}
// M is an exported method, and so should be linkable.
func (T) M() {}

// m is not exported, and so should not be linkable.
func (T) m() {}

var _ = T.m

func _() {
	var t T

	// Embedded fields should be linkable.
	_ = t.Embed //@hover("Embed", "Embed", Embed)

	// Local variables should not be linkable, even if they are capitalized.
	var X int64 //@hover("X", "X", X)
	_ = X

	// Local types should not be linkable, even if they are capitalized.
	type Local struct { //@hover("Local", "Local", Local)
		E
	}

	// But the embedded field should still be linkable.
	var l Local
	_ = l.Embed //@hover("Embed", "Embed", Embed)
}
-- @Embed --
```go
field Embed int64 // through E
```

---

[`(p.E).Embed` on pkg.go.dev](https://pkg.go.dev/mod.com#E.Embed)
-- @F --
```go
field F int64 // size=8, offset=8
```

---

@hover("F", "F", F)


---

[`(p.T).F` on pkg.go.dev](https://pkg.go.dev/mod.com#T.F)
-- @Local --
```go
type Local struct { // size=8
	E
}
```

---

Local types should not be linkable, even if they are capitalized.


```go
// Embedded fields:
Embed int64 // through E 
```
-- @Nested --
```go
field Nested int64 // size=8, offset=0
```

---

Nested fields should also be linkable.
-- @T --
```go
type T struct { // size=32 (0x20)
	f int64 //@hover("f", "f", f)
	F int64 //@hover("F", "F", F)

	E

	// TODO(rfindley): is the link here correct? It ignores N.
	N struct {
		// Nested fields should also be linkable.
		Nested int64 //@hover("Nested", "Nested", Nested)
	}
}
```

---

T is in the package scope, and so should be linkable.


```go
// Embedded fields:
Embed int64 // through E 
```

```go
func (T) M()
func (T) m()
```

---

[`p.T` on pkg.go.dev](https://pkg.go.dev/mod.com#T)
-- @X --
```go
var X int64
```

---

Local variables should not be linkable, even if they are capitalized.
-- @f --
```go
field f int64 // size=8, offset=0
```

---

@hover("f", "f", f)


================================================
FILE: gopls/internal/test/marker/testdata/hover/linkable_generics.txt
================================================
This file contains tests for documentation links to generic code in hover.

-- go.mod --
module mod.com

go 1.19

-- a.go --
package a

import "mod.com/generic"

func _() {
	// Hovering over instantiated object should produce accurate type
	// information, but link to the generic declarations.

	var x generic.GT[int] //@hover("GT", "GT", xGT)
	_ = x.F //@hover("x", "x", x),hover("F", "F", xF)

	f := generic.GF[int] //@hover("GF", "GF", fGF)
	_ = f //@hover("f", "f", f)
}

-- generic/generic.go --
package generic

// Hovering over type parameters should link to documentation.
//
// TODO(rfindley): should it? We should probably link to the type.
type GT[P any] struct{ //@hover("GT", "GT", GT),hover("P", "P", GTP)
	F P //@hover("F", "F", F),hover("P", "P", FP)
}

func (GT[P]) M(p P) { //@hover("GT", "GT", GTrecv),hover("M","M", M),hover(re"p (P)", re"p (P)", pP)
}

func GF[P any] (p P) { //@hover("GF", "GF", GF)
}

-- @F --
```go
field F P
```

---

@hover("F", "F", F),hover("P", "P", FP)


---

[`(generic.GT).F` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT.F)
-- @FP --
```go
type parameter P any
```
-- @GF --
```go
func GF[P any](p P)
```

---

[`generic.GF` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GF)
-- @GT --
```go
type GT[P any] struct {
	F P //@hover("F", "F", F),hover("P", "P", FP)
}
```

---

Hovering over type parameters should link to documentation.

TODO(rfindley): should it? We should probably link to the type.


```go
func (GT[P]) M(p P)
```

---

[`generic.GT` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT)
-- @GTP --
```go
type parameter P any
```
-- @GTrecv --
```go
type GT[P any] struct {
	F P //@hover("F", "F", F),hover("P", "P", FP)
}
```

---

Hovering over type parameters should link to documentation.

TODO(rfindley): should it? We should probably link to the type.


```go
func (GT[P]) M(p P)
```

---

[`generic.GT` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT)
-- @M --
```go
func (GT[P]) M(p P)
```

---

[`(generic.GT).M` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT.M)
-- @f --
```go
var f func(p int)
```
-- @fGF --
```go
func generic.GF(p int) // func[P any](p P)
```

---

[`generic.GF` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GF)
-- @pP --
```go
type parameter P any
```
-- @x --
```go
var x generic.GT[int]
```

---

@hover("GT", "GT", xGT)
-- @xF --
```go
field F int
```

---

@hover("F", "F", F),hover("P", "P", FP)


---

[`(generic.GT).F` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT.F)
-- @xGT --
```go
type GT[P any] struct {
	F P //@hover("F", "F", F),hover("P", "P", FP)
}
```

---

Hovering over type parameters should link to documentation.

TODO(rfindley): should it? We should probably link to the type.


```go
func (generic.GT[P]) M(p P)
```

---

[`generic.GT` on pkg.go.dev](https://pkg.go.dev/mod.com/generic#GT)


================================================
FILE: gopls/internal/test/marker/testdata/hover/linkname.txt
================================================
This test check hover on the 2nd argument in go:linkname directives.

-- go.mod --
module mod.com

-- upper/upper.go --
package upper

import (
	_ "unsafe"
	_ "mod.com/lower"
)

//go:linkname foo mod.com/lower.bar //@hover("mod.com/lower.bar", "mod.com/lower.bar", bar)
func foo() string

-- lower/lower.go --
package lower

// bar does foo.
func bar() string {
	return "foo by bar"
}

var _ = bar

-- @bar --
```go
func bar() string
```

---

bar does foo.


================================================
FILE: gopls/internal/test/marker/testdata/hover/methods.txt
================================================
This test checks the formatting of the list of accessible methods.

Observe that:
- interface methods that appear in the syntax are not repeated
  in the method set of the type;
- promoted methods of structs are shown;
- receiver variables are correctly named;
- receiver variables have a pointer type if appropriate;
- only accessible methods are shown.

-- go.mod --
module example.com

-- lib/lib.go --
package lib

type I interface {
	A()
	b()
	J
}

type J interface { C() }

type S struct { I }
func (s S) A() {}
func (s S) b() {}
func (s *S) PA() {}
func (s *S) pb() {}

var _ = (*S).pb

-- a/a.go --
package a

import "example.com/lib"

var _ lib.I //@hover("I", "I", I)
var _ lib.J //@hover("J", "J", J)
var _ lib.S //@hover("S", "S", S)

-- @I --
```go
type I interface {
	A()
	b()
	J
}
```

---

```go
func (lib.J) C()
```

---

[`lib.I` on pkg.go.dev](https://pkg.go.dev/example.com/lib#I)
-- @J --
```go
type J interface{ C() }
```

---

[`lib.J` on pkg.go.dev](https://pkg.go.dev/example.com/lib#J)
-- @S --
```go
type S struct{ I }
```

---

```go
func (s lib.S) A()
func (lib.J) C()
func (s *lib.S) PA()
```

---

[`lib.S` on pkg.go.dev](https://pkg.go.dev/example.com/lib#S)


================================================
FILE: gopls/internal/test/marker/testdata/hover/pointerdoclink.txt
================================================
This test verifies the fix for golang/go#77329.
Doc links to pointer types should be formatted correctly.

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

type Foo int

type Baz string

// Bar is a [*Foo]
var Bar *Foo //@hover("Bar", "Bar", Bar)

// Buzz is a [*Baz] with trailing space
var Buzz *Baz //@hover("Buzz", "Buzz", Buzz)

-- @Bar --
```go
var Bar *Foo
```

---

Bar is a [\*Foo](file://$WORKDIR/a/a.go#3,6)


---

[`a.Bar` on pkg.go.dev](https://pkg.go.dev/example.com/a#Bar)
-- @Buzz --
```go
var Buzz *Baz
```

---

Buzz is a [\*Baz](file://$WORKDIR/a/a.go#5,6) with trailing space


---

[`a.Buzz` on pkg.go.dev](https://pkg.go.dev/example.com/a#Buzz)


================================================
FILE: gopls/internal/test/marker/testdata/hover/return.txt
================================================
This test checks that hovering over a return statement reveals the result type.

-- a.go --
package a

func _() int {
    return 1 //@hover("return", "return 1", "returns (int)")
}

func _() (int, int) {
    return 1, 2 //@hover("return", "return 1, 2", "returns (int, int)")
}


================================================
FILE: gopls/internal/test/marker/testdata/hover/sizeoffset.txt
================================================
This test checks that hover reports the sizes of vars/types,
and the offsets of struct fields.

Notes:
- this only works on the declaring identifier, not on refs.
- the size of a type is undefined if it depends on type parameters.
- the offset of a field is undefined if it or any preceding field
  has undefined size/alignment.
- the test's size expectations assumes a 64-bit machine.
- requires go1.22 because size information was inaccurate before.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- flags --
-skip_goarch=386,arm

-- go.mod --
module example.com

go 1.18
-- a.go --
package a

type T struct {         //@ hover("T", "T", T)
	a int		//@ hover("a", "a", a)
	U U		//@ hover("U", "U", U)
	y, z int	//@ hover("y", "y", y), hover("z", "z", z)
}

type U struct {
	slice []string
}

type G[T any] struct {
	p T		//@ hover("p", "p", p)
	q int		//@ hover("q", "q", q)
}

var _ struct {
	Gint    G[int]    //@ hover("Gint",    "Gint",    Gint)
	Gstring G[string] //@ hover("Gstring", "Gstring", Gstring)
}

type wasteful struct { //@ hover("wasteful", "wasteful", wasteful)
	a bool
	b [2]string
	c bool
}

type sizeclass struct { //@ hover("sizeclass", "sizeclass", sizeclass)
	a [5]*int
}

-- @T --
```go
type T struct { // size=48 (0x30)
	a    int //@ hover("a", "a", a)
	U    U   //@ hover("U", "U", U)
	y, z int //@ hover("y", "y", y), hover("z", "z", z)
}
```

---

[`a.T` on pkg.go.dev](https://pkg.go.dev/example.com#T)
-- @wasteful --
```go
type wasteful struct { // size=48 (0x30) (29% wasted)
	a bool
	b [2]string
	c bool
}
```
-- @sizeclass --
```go
type sizeclass struct { // size=40 (0x28), class=48 (0x30)
	a [5]*int
}
```
-- @a --
```go
field a int // size=8, offset=0
```

---

@ hover("a", "a", a)
-- @U --
```go
field U U // size=24 (0x18), offset=8
```

---

@ hover("U", "U", U)


---

[`(a.T).U` on pkg.go.dev](https://pkg.go.dev/example.com#T.U)
-- @y --
```go
field y int // size=8, offset=32 (0x20)
```

---

@ hover("y", "y", y), hover("z", "z", z)
-- @z --
```go
field z int // size=8, offset=40 (0x28)
```

---

@ hover("y", "y", y), hover("z", "z", z)
-- @p --
```go
field p T
```

---

@ hover("p", "p", p)
-- @q --
```go
field q int // size=8
```

---

@ hover("q", "q", q)
-- @Gint --
```go
field Gint G[int] // size=16 (0x10), offset=0
```

---

@ hover("Gint",    "Gint",    Gint)
-- @Gstring --
```go
field Gstring G[string] // size=24 (0x18), offset=16 (0x10)
```

---

@ hover("Gstring", "Gstring", Gstring)


================================================
FILE: gopls/internal/test/marker/testdata/hover/std.txt
================================================
This test checks hover results for built-in or standard library symbols.

It uses synopsis documentation as full documentation for some of these
built-ins varies across Go versions, where as it just so happens that the
synopsis does not.

In the future we may need to limit this test to the latest Go version to avoid
documentation churn.

-- settings.json --
{
	"hoverKind": "SynopsisDocumentation"
}

-- go.mod --
module mod.com

go 1.18

-- std.go --
package std

import (
	"fmt"
	"go/types"
	"sync"
)

func _() {
	var err error         //@loc(err, "err")
	fmt.Printf("%v", err) //@def("err", err)

	var _ string       //@hover("string", "string", hoverstring)
	_ = make([]int, 0) //@hover("make", "make", hovermake)

	var mu sync.Mutex
	mu.Lock() //@hover("Lock", "Lock", hoverLock)

	var typ *types.Named //@hover("types", "types", hoverTypes)
	typ.Obj().Name()     //@hover("Name", "Name", hoverName)
}
-- @hoverLock --
```go
func (m *sync.Mutex) Lock()
```

---

Lock locks m.


---

[`(sync.Mutex).Lock` on pkg.go.dev](https://pkg.go.dev/sync#Mutex.Lock)
-- @hoverName --
```go
func (obj *types.object) Name() string
```

---

Name returns the object's (package-local, unqualified) name.


---

[`(types.TypeName).Name` on pkg.go.dev](https://pkg.go.dev/go/types#TypeName.Name)
-- @hoverTypes --
```go
package types
```

---

Package types declares the data types and implements the algorithms for type-checking of Go packages.


---

[`types` on pkg.go.dev](https://pkg.go.dev/go/types)
-- @hovermake --
```go
func make(t Type, size ...int) Type
```

---

The make built-in function allocates and initializes an object of type slice, map, or chan (only).


---

[`make` on pkg.go.dev](https://pkg.go.dev/builtin#make)
-- @hoverstring --
```go
type string string
```

---

string is the set of all strings of 8-bit bytes, conventionally but not necessarily representing UTF-8-encoded text.


---

[`string` on pkg.go.dev](https://pkg.go.dev/builtin#string)


================================================
FILE: gopls/internal/test/marker/testdata/hover/structfield.txt
================================================
This test checks that the complete struct field is
shown on hover (including struct tags and comments).

-- go.mod --
module example.com

-- lib/lib.go --
package lib

type Something struct {
    // Field with a tag
    Field int `json:"field"`
}

func DoSomething() Something {
    var s Something
    s.Field = 42  //@hover("i", "Field", field)
    return s
}

-- @field --
```go
field Field int `json:"field"`
```

---

Field with a tag


---

[`(lib.Something).Field` on pkg.go.dev](https://pkg.go.dev/example.com/lib#Something.Field)


================================================
FILE: gopls/internal/test/marker/testdata/implementation/basic.txt
================================================
Basic test of implementation query.

-- go.mod --
module example.com
go 1.18

-- implementation/implementation.go --
package implementation

import "example.com/other"

type ImpP struct{} //@loc(ImpP, "ImpP"),implementation("ImpP", Laugher, OtherLaugher)

func (*ImpP) Laugh() { //@loc(LaughP, "Laugh"),implementation("Laugh", Laugh, OtherLaugh)
}

type ImpS struct{} //@loc(ImpS, "ImpS"),implementation("ImpS", Laugher, OtherLaugher)

func (ImpS) Laugh() { //@loc(LaughS, "Laugh"),implementation("Laugh", Laugh, OtherLaugh)
}

type Laugher interface { //@loc(Laugher, "Laugher"),implementation("Laugher", ImpP, OtherImpP, ImpS, OtherLaugher, OtherImpS, EmbedsImpP)
	Laugh() //@loc(Laugh, "Laugh"),implementation("Laugh", LaughP, OtherLaughP, LaughS, OtherLaugh, OtherLaughS)
}

type Foo struct { //@implementation("Foo", Joker)
	other.Foo
}

type Joker interface { //@loc(Joker, "Joker")
	Joke() //@loc(Joke, "Joke"),implementation("Joke", ImpJoker)
}

type cryer int //@implementation("cryer", Cryer)

func (cryer) Cry(other.CryType) {} //@loc(CryImpl, "Cry"),implementation("Cry", Cry)

type Empty any //@implementation("Empty")

var _ interface{ Joke() } //@implementation("Joke", Joke, ImpJoker)

type EmbedsImpP struct { //@loc(EmbedsImpP, "EmbedsImpP")
	ImpP //@implementation("ImpP", Laugher, OtherLaugher)
}

var _ error //@defloc(StdError, "error")

type MyError struct {} //@implementation("MyError", StdError)

func (MyError) Error() string { return "bah" }

-- other/other.go --
package other

type ImpP struct{} //@loc(OtherImpP, "ImpP")

func (*ImpP) Laugh() { //@loc(OtherLaughP, "Laugh")
}

type ImpS struct{} //@loc(OtherImpS, "ImpS")

func (ImpS) Laugh() { //@loc(OtherLaughS, "Laugh")
}

type ImpI interface { //@loc(OtherLaugher, "ImpI")
	Laugh() //@loc(OtherLaugh, "Laugh")
}

type Foo struct { //@implementation("Foo", Joker)
}

func (Foo) Joke() { //@loc(ImpJoker, "Joke"),implementation("Joke", Joke)
}

type CryType int

type Cryer interface { //@loc(Cryer, "Cryer")
	Cry(CryType) //@loc(Cry, "Cry"),implementation("Cry", CryImpl)
}


================================================
FILE: gopls/internal/test/marker/testdata/implementation/generics-basicalias.txt
================================================
Test of special case of 'implementation' query: aliases of basic types
(rune vs int32) in the "tricky" (=generic) algorithm for unifying
method signatures.

We test both the local (intra-package) and global (cross-package)
algorithms.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

type C[T any] struct{}
func (C[T]) F(rune, T) {} //@ loc(aCF, "F"), implementation("F", aIF, bIF)

type I[T any] interface{ F(int32, T) } //@ loc(aIF, "F"), implementation("F", aCF, bCF, bIF)

-- b/b.go --
package b

type C[T any] struct{}
func (C[T]) F(rune, T) {} //@ loc(bCF, "F"), implementation("F", aIF, bIF)

type I[T any] interface{ F(int32, T) } //@ loc(bIF, "F"), implementation("F", aCF, aIF, bCF)


================================================
FILE: gopls/internal/test/marker/testdata/implementation/generics.txt
================================================
Test of 'implementation' query on generic types.

-- go.mod --
module example.com
go 1.18

-- implementation/implementation.go --
package implementation

type GenIface[T any] interface { //@loc(GenIface, "GenIface"),implementation("GenIface", GC, GenConc, GI, GIString, GenConcString)
	F(int, string, T) //@loc(GenIfaceF, "F"),implementation("F", GCF, GenConcF, GIF)
}

type GenConc[U any] int //@loc(GenConc, "GenConc"),implementation("GenConc", GI, GIString, GenIface)

func (GenConc[V]) F(int, string, V) {} //@loc(GenConcF, "F"),implementation("F", GIF, GenIfaceF)

type GenConcString struct{ GenConc[string] } //@loc(GenConcString, "GenConcString"),implementation(GenConcString, GIString, GI, GenIface)

-- other/other.go --
package other

type GI[T any] interface { //@loc(GI, "GI"),implementation("GI", GenConc, GenIface, GenConcString, GIString, GC)
	F(int, string, T) //@loc(GIF, "F"),implementation("F", GenIfaceF, GenConcF, GCF)
}

type GIString GI[string] //@loc(GIString, "GIString"),implementation("GIString", GenConcString, GenIface, GenConc, GI, GC)

type GC[U any] int //@loc(GC, "GC"),implementation("GC", GenIface, GI, GIString)

func (GC[V]) F(int, string, V) {} //@loc(GCF, "F"),implementation("F", GenIfaceF, GIF)


================================================
FILE: gopls/internal/test/marker/testdata/implementation/issue43655.txt
================================================
This test verifies that we fine implementations of the built-in error interface.

-- go.mod --
module example.com
go 1.18

-- p.go --
package p

type errA struct{ error } //@loc(errA, "errA")

type errB struct{} //@loc(errB, "errB")
func (errB) Error() string{ return "" } //@loc(errBError, "Error")

type notAnError struct{}
func (notAnError) Error() int { return 0 }

func _() {
	var _ error //@implementation("error", errA, errB)
	var a errA
	_ = a.Error //@implementation("Error", errBError)
}


================================================
FILE: gopls/internal/test/marker/testdata/implementation/issue67041.txt
================================================
This test verifies that Implementations uses the correct object when querying
local implementations. As described in golang/go#67041, a bug led to it
comparing types from different realms.

-- go.mod --
module example.com

go 1.18

-- a/a.go --
package a

type A struct{}

type Aer interface { //@loc(Aer, "Aer")
	GetA() A
}

type X struct{} //@loc(X, "X")

func (X) GetA() A

-- a/a_test.go --
package a

// Verify that we also find implementations in a test variant.
type Y struct{} //@loc(Y, "Y")

func (Y) GetA() A
-- b/b.go --
package b

import "example.com/a"

var _ a.X //@implementation("X", Aer)

var _ a.Aer //@implementation("Aer", X, Y)


================================================
FILE: gopls/internal/test/marker/testdata/implementation/issue68641.txt
================================================
Regression test that Implementation(I) returns J even when I and J are
both interfaces; see issue #68641. Previously, interface/interface
matches were never reported.

However, the direction of the query is determined by the concreteness
of the query type: Implements on a.B, an interface, reports types that
are assignable to it, a.C; but Implements on concrete a.impl reports
only interface types to which it may be assigned, and there is no way
to query from interface B to find the (wider) interface A. (This would
be a useful feature of LSP though; see
https://github.com/microsoft/language-server-protocol/issues/2037.)

The test exercises both the local (intra-) and global (cross-package)
algorithms and checks that they are consistent.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type A interface { //@ loc(aA, "A"), implementation("A", aB, aC, aimpl, bA, bB, bC, bimpl)
	A() //@ loc(aAA, "A"), implementation("A", aimplA, bimplA, bAA)
}

type B interface { //@ loc(aB, "B"), implementation("B", aC, aimpl, bB, bC, bimpl)
	A
	B()
}

type C interface { //@ loc(aC, "C"), implementation("C", aimpl, bC, bimpl)
	B
	C()
}

type impl int //@ loc(aimpl, "impl"), implementation("impl", aA, aB, aC, bA, bB, bC)

func (impl) A() //@ loc(aimplA, "A")
func (impl) B()
func (impl) C()

-- b/b.go --
package b

type A interface { //@ loc(bA, "A"), implementation("A", aA, aB, aC, aimpl, bB, bC, bimpl)
	A() //@ loc(bAA, "A")
}

type B interface { //@ loc(bB, "B"), implementation("B", aB, aC, aimpl, bC, bimpl)
	A
	B()
}

type C interface { //@ loc(bC, "C"), implementation("C", aC, aimpl, bimpl)
	B
	C()
}

type impl int //@ loc(bimpl, "impl"), implementation("impl", aA, aB, aC, bA, bB, bC)

func (impl) A() //@ loc(bimplA, "A")
func (impl) B()
func (impl) C()


================================================
FILE: gopls/internal/test/marker/testdata/implementation/issue74305.txt
================================================
Regression test for a crash, #74305.

-- go.mod --
module example.com

go 1.18

-- a/a.go --
package a

var _ = undefined() //@ diag("undefined", re"undefined"), implementation("(", err="not a dynamic function call")


================================================
FILE: gopls/internal/test/marker/testdata/implementation/signature.txt
================================================
Test of local Implementation queries using function signatures.

Assertions:
- Query on "func" of a function type returns the corresponding concrete functions.
- Query on "func" of a concrete function returns corresponding function types.
- Query on "(" of a dynamic function call returns corresponding function types.
- Different signatures (Nullary vs Handler) don't correspond.

The @loc markers use the suffixes Func, Type, Call for the three kinds.
Each query maps between these two sets: {Func} <=> {Type,Call}.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

// R is short for Record.
type R struct{}

// H is short for Handler.
type H func(*R) //@ loc(HType, "func"), implementation("func", aFunc, bFunc, cFunc)

func aFunc(*R) {} //@ loc(aFunc, "func"), implementation("func", HType, hParamType, hCall)

var bFunc = func(*R) {} //@ loc(bFunc, "func"), implementation("func", hParamType, hCall, HType)

func nullary() { //@ loc(nullaryFunc, "func"), implementation("func", Nullary, fieldCall)
	cFunc := func(*R) {} //@ loc(cFunc, "func"), implementation("func", hParamType, hCall, HType)
	_ = cFunc
}

type Nullary func() //@ loc(Nullary, "func")

func _(
	h func(*R)) { //@ loc(hParamType, "func"), implementation("func", aFunc, bFunc, cFunc)

	_ = aFunc    // pacify unusedfunc
	_ = bFunc    // pacify unusedfunc
	_ = nullary  // pacify unusedfunc
	_ = h

	h(nil) //@ loc(hCall, "("), implementation("(", aFunc, bFunc, cFunc)
}

// generics:

func _[T any](complex128) {
	f1 := func(T)      int { return 0 } //@ loc(f1Func, "func"), implementation("func", fParamType, fCall, f1Call, f2Call)
	f2 := func(string) int { return 0 } //@ loc(f2Func, "func"), implementation("func", fParamType, fCall, f1Call, f2Call)
	f3 := func(int)    int { return 0 } //@ loc(f3Func, "func"), implementation("func", f1Call)

	f1(*new(T)) //@ loc(f1Call, "("), implementation("(", f1Func, f2Func, f3Func, f4Func)
	f2("")      //@ loc(f2Call, "("), implementation("(", f1Func, f2Func, f4Func)
	_ = f3      // not called
}

func f4[T any](T) int { return 0 } //@ loc(f4Func, "func"), implementation("func", fParamType, fCall, f1Call, f2Call)

var _ = f4[string] // pacify unusedfunc

func _(
	f func(string) int, //@ loc(fParamType, "func"), implementation("func", f1Func, f2Func, f4Func)
	err error) {

	f("") //@ loc(fCall, "("), implementation("(", f1Func, f2Func, f4Func)

	struct{x Nullary}{}.x() //@ loc(fieldCall, "("), implementation("(", nullaryFunc)

	// Calls that are not dynamic function calls:
	_ = len("")          //@ implementation("(", err="not a dynamic function call")
	_ = int(0)           //@ implementation("(", err="not a dynamic function call")
	_ = error.Error(nil) //@ implementation("(", err="not a dynamic function call")
	_ = err.Error()      //@ implementation("(", err="not a dynamic function call")
	_ = f4(0)            //@ implementation("(", err="not a dynamic function call"), loc(f4Call, "(")
}





================================================
FILE: gopls/internal/test/marker/testdata/inlayhints/ignored-error.txt
================================================
Test of "ignore error" inlay hint (#73930).

- f.Close() generates a hint, except when followed by
  an "// ignore error" comment, or in a "_ = f.Close()" stmt.
- fmt.Println() is exempted.

-- settings.json --
{"hints": {"ignoredError": true}}

-- p/p.go --
package p //@inlayhints(out)

import ( "os"; "fmt" )

func _(f *os.File) {
	f.WriteString("hello")
	f.Close()
}

func _(f *os.File) {
	f.Close() // irrelevant comment
}

func _(f *os.File) {
	f.Close() // ignore error
}

func _(f *os.File) {
	_ = f.Close()
}

func _() {
	fmt.Println()
}

func _(f *os.File) {
	// Allow horizontal space before comment.
	new(os.File).Close() // ignore error
	f.Close()            // ignore error
}

-- @out --
package p //@inlayhints(out)

import ( "os"; "fmt" )

func _(f *os.File) {
	f.WriteString("hello")< // ignore error>
	f.Close()< // ignore error>
}

func _(f *os.File) {
	f.Close()< // ignore error> // irrelevant comment
}

func _(f *os.File) {
	f.Close() // ignore error
}

func _(f *os.File) {
	_ = f.Close()
}

func _() {
	fmt.Println()
}

func _(f *os.File) {
	// Allow horizontal space before comment.
	new(os.File).Close() // ignore error
	f.Close()            // ignore error
}



================================================
FILE: gopls/internal/test/marker/testdata/inlayhints/inlayhints.txt
================================================

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"hints": {
		"assignVariableTypes": true,
		"compositeLiteralFields": true,
		"compositeLiteralTypes": true,
		"constantValues": true,
		"functionTypeParameters": true,
		"parameterNames": true,
		"rangeVariabletypes": true
	}
}

-- composite_literals.go --
package inlayHint //@inlayhints(complit)

import "fmt"

func fieldNames() {
	for _, c := range []struct {
		in, want string
	}{
		struct{ in, want string }{"Hello, world", "dlrow ,olleH"},
		{"Hello, 世界", "界世 ,olleH"},
		{"", ""},
	} {
		fmt.Println(c.in == c.want)
	}
}

func fieldNamesPointers() {
	for _, c := range []*struct {
		in, want string
	}{
		&struct{ in, want string }{"Hello, world", "dlrow ,olleH"},
		{"Hello, 世界", "界世 ,olleH"},
		{"", ""},
	} {
		fmt.Println(c.in == c.want)
	}
}

-- @complit --
package inlayHint //@inlayhints(complit)

import "fmt"

func fieldNames() {
	for _, c := range []struct {
		in, want string
	}{
		struct{ in, want string }{<in: >"Hello, world", <want: >"dlrow ,olleH"},
		<struct{in string; want string}>{<in: >"Hello, 世界", <want: >"界世 ,olleH"},
		<struct{in string; want string}>{<in: >"", <want: >""},
	} {
		fmt.Println(<a...: >c.in == c.want)
	}
}

func fieldNamesPointers() {
	for _, c := range []*struct {
		in, want string
	}{
		&struct{ in, want string }{<in: >"Hello, world", <want: >"dlrow ,olleH"},
		<&struct{in string; want string}>{<in: >"Hello, 世界", <want: >"界世 ,olleH"},
		<&struct{in string; want string}>{<in: >"", <want: >""},
	} {
		fmt.Println(<a...: >c.in == c.want)
	}
}

-- constant_values.go --
package inlayHint //@inlayhints(values)

const True = true

type Kind int

const (
	KindNone Kind = iota
	KindPrint
	KindPrintf
	KindErrorf
)

const (
	u         = iota * 4
	v float64 = iota * 42
	w         = iota * 42
)

const (
	a, b = 1, 2
	c, d
	e, f = 5 * 5, "hello" + "world"
	g, h
	i, j = true, f
)

// No hint
const (
	Int     = 3
	Float   = 3.14
	Bool    = true
	Rune    = '3'
	Complex = 2.7i
	String  = "Hello, world!"
)

var (
	varInt     = 3
	varFloat   = 3.14
	varBool    = true
	varRune    = '3' + '4'
	varComplex = 2.7i
	varString  = "Hello, world!"
)

-- @values --
package inlayHint //@inlayhints(values)

const True = true

type Kind int

const (
	KindNone Kind = iota< = 0>
	KindPrint< = 1>
	KindPrintf< = 2>
	KindErrorf< = 3>
)

const (
	u         = iota * 4< = 0>
	v float64 = iota * 42< = 42>
	w         = iota * 42< = 84>
)

const (
	a, b = 1, 2
	c, d< = 1, 2>
	e, f = 5 * 5, "hello" + "world"< = 25, "helloworld">
	g, h< = 25, "helloworld">
	i, j = true, f< = true, "helloworld">
)

// No hint
const (
	Int     = 3
	Float   = 3.14
	Bool    = true
	Rune    = '3'
	Complex = 2.7i
	String  = "Hello, world!"
)

var (
	varInt     = 3
	varFloat   = 3.14
	varBool    = true
	varRune    = '3' + '4'
	varComplex = 2.7i
	varString  = "Hello, world!"
)

-- parameter_names.go --
package inlayHint //@inlayhints(parameters)

import "fmt"

func hello(name string) string {
	return "Hello " + name
}

func helloWorld() string {
	return hello("World")
}

type foo struct{}

func (*foo) bar(baz string, qux int) int {
	if baz != "" {
		return qux + 1
	}
	return qux
}

func kase(foo int, bar bool, baz ...string) {
	fmt.Println(foo, bar, baz)
}

func kipp(foo string, bar, baz string) {
	fmt.Println(foo, bar, baz)
}

func plex(foo, bar string, baz string) {
	fmt.Println(foo, bar, baz)
}

func tars(foo string, bar, baz string) {
	fmt.Println(foo, bar, baz)
}

func foobar() {
	var x foo
	x.bar("", 1)
	kase(0, true, "c", "d", "e")
	kipp("a", "b", "c")
	plex("a", "b", "c")
	tars("a", "b", "c")
	foo, bar, baz := "a", "b", "c"
	kipp(foo, bar, baz)
	plex("a", bar, baz)
	tars(foo+foo, (bar), "c")

}

-- @parameters --
package inlayHint //@inlayhints(parameters)

import "fmt"

func hello(name string) string {
	return "Hello " + name
}

func helloWorld() string {
	return hello(<name: >"World")
}

type foo struct{}

func (*foo) bar(baz string, qux int) int {
	if baz != "" {
		return qux + 1
	}
	return qux
}

func kase(foo int, bar bool, baz ...string) {
	fmt.Println(<a...: >foo, bar, baz)
}

func kipp(foo string, bar, baz string) {
	fmt.Println(<a...: >foo, bar, baz)
}

func plex(foo, bar string, baz string) {
	fmt.Println(<a...: >foo, bar, baz)
}

func tars(foo string, bar, baz string) {
	fmt.Println(<a...: >foo, bar, baz)
}

func foobar() {
	var x foo
	x.bar(<baz: >"", <qux: >1)
	kase(<foo: >0, <bar: >true, <baz...: >"c", "d", "e")
	kipp(<foo: >"a", <bar: >"b", <baz: >"c")
	plex(<foo: >"a", <bar: >"b", <baz: >"c")
	tars(<foo: >"a", <bar: >"b", <baz: >"c")
	foo< string>, bar< string>, baz< string> := "a", "b", "c"
	kipp(foo, bar, baz)
	plex(<foo: >"a", bar, baz)
	tars(<foo: >foo+foo, <bar: >(bar), <baz: >"c")

}

-- type_params.go --
package inlayHint //@inlayhints(typeparams)

func main() {
	ints := map[string]int64{
		"first":  34,
		"second": 12,
	}

	floats := map[string]float64{
		"first":  35.98,
		"second": 26.99,
	}

	SumIntsOrFloats[string, int64](ints)
	SumIntsOrFloats[string, float64](floats)

	SumIntsOrFloats(ints)
	SumIntsOrFloats(floats)

	SumNumbers(ints)
	SumNumbers(floats)
}

type Number interface {
	int64 | float64
}

func SumIntsOrFloats[K comparable, V int64 | float64](m map[K]V) V {
	var s V
	for _, v := range m {
		s += v
	}
	return s
}

func SumNumbers[K comparable, V Number](m map[K]V) V {
	var s V
	for _, v := range m {
		s += v
	}
	return s
}

-- @typeparams --
package inlayHint //@inlayhints(typeparams)

func main() {
	ints< map[string]int64> := map[string]int64{
		"first":  34,
		"second": 12,
	}

	floats< map[string]float64> := map[string]float64{
		"first":  35.98,
		"second": 26.99,
	}

	SumIntsOrFloats[string, int64](<m: >ints)
	SumIntsOrFloats[string, float64](<m: >floats)

	SumIntsOrFloats<[string, int64]>(<m: >ints)
	SumIntsOrFloats<[string, float64]>(<m: >floats)

	SumNumbers<[string, int64]>(<m: >ints)
	SumNumbers<[string, float64]>(<m: >floats)
}

type Number interface {
	int64 | float64
}

func SumIntsOrFloats[K comparable, V int64 | float64](m map[K]V) V {
	var s V
	for _, v := range m {
		s += v
	}
	return s
}

func SumNumbers[K comparable, V Number](m map[K]V) V {
	var s V
	for _, v := range m {
		s += v
	}
	return s
}

-- variable_types.go --
package inlayHint //@inlayhints(vartypes)

func assignTypes() {
	var x string
	var y = ""
	i, j := 0, len([]string{})-1
	println(i, j)
}

func rangeTypes() {
	for k, v := range []string{} {
		println(k, v)
	}
}

func funcLitType() {
	myFunc := func(a string) string { return "" }
}

func compositeLitType() {
	foo := map[string]any{"": ""}
}

-- @vartypes --
package inlayHint //@inlayhints(vartypes)

func assignTypes() {
	var x string
	var y = ""
	i< int>, j< int> := 0, len([]string{})-1
	println(i, j)
}

func rangeTypes() {
	for k, v := range []string{} {
		println(k, v)
	}
}

func funcLitType() {
	myFunc< func(a string) string> := func(a string) string { return "" }
}

func compositeLitType() {
	foo< map[string]any> := map[string]any{"": ""}
}



================================================
FILE: gopls/internal/test/marker/testdata/inlayhints/issue67142.txt
================================================
Regression test for golang/go#67142.

-- flags --
-ignore_extra_diags

-- settings.json --
{
	"hints": {
		"assignVariableTypes": true,
		"compositeLiteralFields": true,
		"compositeLiteralTypes": true,
		"constantValues": true,
		"functionTypeParameters": true,
		"parameterNames": true,
		"rangeVariabletypes": true
	}
}

-- go.mod --
module w

go 1.21.9

-- p.go --
//@inlayhints(out)
package p

var _ = rand.Float64()

-- @out --
//@inlayhints(out)
package p

var _ = rand.Float64()



================================================
FILE: gopls/internal/test/marker/testdata/links/links.txt
================================================
This test verifies behavior of textDocument/documentLink.

-- go.mod --
module golang.org/lsptests

go 1.18
-- foo/foo.go --
package foo

type StructFoo struct {}

-- links/links.go --
package links //@documentlink(links)

import (
	"fmt"

	"golang.org/lsptests/foo"

	_ "database/sql"
)

var (
	_ fmt.Formatter
	_ foo.StructFoo
	_ errors.Formatter //@diag("errors", re"(undeclared|undefined)")
)

// Foo function
func Foo() string {
	/*https://example.com/comment */

	url := "https://example.com/string_literal"
	return url

	// TODO(golang/go#1234): Link the relevant issue.
	// TODO(microsoft/vscode-go#12): Another issue.
}

-- @links --
links/links.go:4:3-6 https://pkg.go.dev/fmt
links/links.go:6:3-26 https://pkg.go.dev/golang.org/lsptests/foo
links/links.go:8:5-17 https://pkg.go.dev/database/sql
links/links.go:21:10-44 https://example.com/string_literal
links/links.go:19:4-31 https://example.com/comment
links/links.go:24:10-24 https://github.com/golang/go/issues/1234
links/links.go:25:10-32 https://github.com/microsoft/vscode-go/issues/12


================================================
FILE: gopls/internal/test/marker/testdata/mcptools/context.txt
================================================
This test exercises the "go_context" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- settings.json --
{
    "mcpTools": {
        "go_context": true
    }
}

-- go.mod --
module example.com

-- a/main.go --
// File doc for main.go part 1.
package main

// File doc for main.go part 2.
import(
    "example.com/a/comment"
)

// File doc for main.go part 3.

// doc comment for func foo.
func foo() {//@mcptool("go_context", `{"file": "$WORKDIR/a/main.go"}`, output=withComment)
    comment.Foo("", 0)
}

-- a/a.go --
// File doc for a.go.
package main

// doc comment for func a.
func a () {}

// doc comment for type b.
type b struct {}

// doc comment for const c.
const c = ""

// doc comment for var d.
var d int

-- a/comment/doc.go --
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package doc for package comment.
*/
package comment

-- a/comment/comment.go --
// File doc for comment.go part 1.
package comment

// File doc for comment.go part 2.
import (
    // comment for package renaming.
    myfmt "fmt"
)

// File doc for comment.go part 3.

// doc comment for comment.Foo
func Foo(foo string, _ int) {
    myfmt.Printf("%s", foo)
}

// Random comment floating around.

-- @withComment --
Current package "example.com/a" (package main):

main.go (current file):
```go
// File doc for main.go part 1.
package main

// File doc for main.go part 2.
import(
    "example.com/a/comment"
)

// File doc for main.go part 3.

// doc comment for func foo.
func foo()

```

a.go:
```go
// File doc for a.go.
package main

// doc comment for func a.
func a ()

// doc comment for type b.
type b struct {}
// doc comment for const c.
const c = ""
// doc comment for var d.
var d int
```

Current file "main.go" contains this import declaration:
```go
import(
    "example.com/a/comment"
)
```

The imported packages declare the following symbols:

"example.com/a/comment" (package comment)
comment.go:
```go
// File doc for comment.go part 1.
package comment

// File doc for comment.go part 2.
import (
    // comment for package renaming.
    myfmt "fmt"
)

// File doc for comment.go part 3.

// doc comment for comment.Foo
func Foo(foo string, _ int)

```

doc.go:
```go
/*
Package doc for package comment.
*/
package comment

```

-- b/main.go --
package main

import(
    "example.com/b/function"
)

func testFunction() {//@mcptool("go_context", `{"file":"$WORKDIR/b/main.go"}`, output=withFunction)
    function.Foo(0, "")
}

-- b/function/function.go --
package function

func Foo(int, string) {}

func foo(string, int) {}

type unexported struct {}

func (*unexported) unexported(int) {}

func (*unexported) Exported(int) {}

type Exported struct{}

func (*Exported) unexported(int) {}

func (*Exported) Exported(int) {}

-- @withFunction --
Current package "example.com/b" (package main):

main.go (current file):
```go
package main

import(
    "example.com/b/function"
)

func testFunction()

```

Current file "main.go" contains this import declaration:
```go
import(
    "example.com/b/function"
)
```

The imported packages declare the following symbols:

"example.com/b/function" (package function)
function.go:
```go
package function

func Foo(int, string)

type Exported struct{}

func (*Exported) Exported(int)

```

-- c/main.go --
package main

import(
    "example.com/c/types"
)

var x types.Exported //@mcptool("go_context", `{"file":"$WORKDIR/c/main.go"}`, output=withType)

-- c/types/types.go --
package types

// Doc for exported.
type Exported struct {
    // Doc for exported.
    Exported string
    // Doc for unexported.
    unexported string
}

// Doc for types.
type (
    // Doc for Foo first line.
    // Doc for Foo second line.
    Foo struct {
        foo string
    }

    // Doc for foo.
    foo struct {}

    // Doc for Bar.
    Bar struct {
        bar string
    }

    // Doc for bar.
    bar struct {}
)

-- @withType --
Current package "example.com/c" (package main):

main.go (current file):
```go
package main

import(
    "example.com/c/types"
)

var x types.Exported
```

Current file "main.go" contains this import declaration:
```go
import(
    "example.com/c/types"
)
```

The imported packages declare the following symbols:

"example.com/c/types" (package types)
types.go:
```go
package types

// Doc for exported.
type Exported struct {
    // Doc for exported.
    Exported string
    // Doc for unexported.
    unexported string
}

// Doc for types.
type (
    // Doc for Foo first line.
    // Doc for Foo second line.
    Foo struct {
        foo string
    }
    // Doc for Bar.
    Bar struct {
        bar string
    }
)

```

-- d/main.go --
package main

import(
    "example.com/d/values"
)

var y values.ConstFoo //@mcptool("go_context", `{"file":"$WORKDIR/d/main.go"}`, output=withValue)

-- d/values/consts.go --
package values

const (
    // doc for ConstFoo
    ConstFoo = "Foo" // comment for ConstFoo
    // doc for constFoo
    constFoo = "foo" // comment for constFoo
    // doc for ConstBar
    ConstBar = "Bar" // comment for ConstBar
    // doc for constBar
    constBar = "bar" // comment for constBar
)

// doc for ConstExported
const ConstExported = "Exported" // comment for ConstExported

// doc for constUnexported
var constUnexported = "unexported" // comment for constUnexported

-- d/values/vars.go --
package values

var (
    // doc for VarFoo
    VarFoo = "Foo" // comment for VarFoo
    // doc for varFoo
    varFoo = "foo" // comment for varFoo
    // doc for VarBar
    VarBar = "Bar" // comment for VarBar
    // doc for varBar
    varBar = "bar" // comment for varBar
)

// doc for VarExported
var VarExported = "Exported" // comment for VarExported

// doc for varUnexported
var varUnexported = "unexported" // comment for varUnexported

-- @withValue --
Current package "example.com/d" (package main):

main.go (current file):
```go
package main

import(
    "example.com/d/values"
)

var y values.ConstFoo
```

Current file "main.go" contains this import declaration:
```go
import(
    "example.com/d/values"
)
```

The imported packages declare the following symbols:

"example.com/d/values" (package values)
consts.go:
```go
package values

const (
    // doc for ConstFoo
    ConstFoo = "Foo" // comment for ConstFoo
    // doc for ConstBar
    ConstBar = "Bar" // comment for ConstBar
)

// doc for ConstExported
const ConstExported = "Exported" // comment for ConstExported

```

vars.go:
```go
package values

var (
    // doc for VarFoo
    VarFoo = "Foo" // comment for VarFoo
    // doc for VarBar
    VarBar = "Bar" // comment for VarBar
)

// doc for VarExported
var VarExported = "Exported" // comment for VarExported

```

-- e/main.go --
package main

func main() {} //@mcptool("go_context", `{"file":"$WORKDIR/e/main.go"}`, output=samePackage)

-- e/foo.go --
package main

var (
    foo string
    Foo string
)

-- e/bar.go --
package main

const (
    bar = ""
    Bar = ""
)

-- e/baz.go --
package main

func baz(int) string {
    return ""
}

func Baz(string) int {
    return 0
}

-- @samePackage --
Current package "example.com/e" (package main):

main.go (current file):
```go
package main

func main()

```

bar.go:
```go
package main

const (
    bar = ""
    Bar = ""
)
```

baz.go:
```go
package main

func baz(int) string

func Baz(string) int

```

foo.go:
```go
package main

var (
    foo string
    Foo string
)
```

-- f/main.go --
package main

import "fmt"

func Foo() { //@mcptool("go_context", `{"file":"$WORKDIR/f/main.go"}`, output=withoutStdLib)
    fmt.Println("foo")
}

-- @withoutStdLib --
Current package "example.com/f" (package main):

main.go (current file):
```go
package main

import "fmt"

func Foo()

```

Current file "main.go" contains this import declaration:
```go
import "fmt"
```



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/file_context.txt
================================================
This test exercises the "go_file_context" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

-- a/main.go --
package main

import "example.com/a/other"

func main() { //@mcptool("go_file_context", `{"file": "$WORKDIR/a/main.go"}`, output=content)
	other.Foo()
	_ = other.Bar
}

-- a/other/other.go --
package other

// Foo should have a doc comment.
func Foo() {
	// The body should be ignored
}

var Bar int // line comments get dropped

var Baz string // Baz is not referenced

-- @content --
File `$WORKDIR/a/main.go` is in package "example.com/a".
Below is a summary of the APIs it uses from other files.
To read the full API of any package, use go_package_api.
Referenced declarations from $WORKDIR/a/other/other.go (package "example.com/a/other"):
```go
// Foo should have a doc comment.
func Foo()

var Bar int
```



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/file_diagnostics.txt
================================================
This test exercises the "go_file_diagnostics" MCP tool.

Some diagnostics from the "printf" analyzer carry fixes, and those fixes have edits.
(Not all fixes have edits; some analyzers rely on gopls to compute them lazily.)

The printf analyzer only reports a fix in files using >= go1.24.

-- flags --
-mcp
-min_go_command=go1.24

-- settings.json --
{
    "mcpTools": {
        "go_file_diagnostics": true
    }
}

-- go.mod --
module example.com
go 1.24

-- a/main.go --
package main

func foo() {} //@loc(foo, "foo")

//@mcptool("go_file_diagnostics", `{"file":"$WORKDIR/a/main.go"}`, output=unused)
//@diag(foo, re"unused")
-- @unused --
2:5-2:8: [Information] function "foo" is unused
Fix:
--- $WORKDIR/a/main.go
+++ $WORKDIR/a/main.go
@@ -1,6 +1,6 @@
 package main
 
-func foo() {} //@loc(foo, "foo")
+
 
 //@mcptool("go_file_diagnostics", `{"file":"$WORKDIR/a/main.go"}`, output=unused)
 //@diag(foo, re"unused")


-- b/main.go --
package main

import "fmt"

// (diagnostic with fix)
var (
	msg string
	_ = fmt.Sprintf(msg) //@ diag("msg", re"non-constant format string")
)

// (diagnostic without fix)
var _ = fmt.Sprintf("%d", "hello") //@ diag("%d", re"%d .* wrong type string")

//@ mcptool("go_file_diagnostics", `{"file":"$WORKDIR/b/main.go"}`, output=diagnosePrintf)

-- @diagnosePrintf --
7:17-7:20: [Warning] non-constant format string in call to fmt.Sprintf
Fix:
--- $WORKDIR/b/main.go
+++ $WORKDIR/b/main.go
@@ -5,7 +5,7 @@
 // (diagnostic with fix)
 var (
 	msg string
-	_ = fmt.Sprintf(msg) //@ diag("msg", re"non-constant format string")
+	_ = fmt.Sprintf("%s", msg) //@ diag("msg", re"non-constant format string")
 )
 
 // (diagnostic without fix)


11:21-11:23: [Warning] fmt.Sprintf format %d has arg "hello" of wrong type string


================================================
FILE: gopls/internal/test/marker/testdata/mcptools/file_metadata.txt
================================================
This test exercises the "go_file_metadata" MCP tool.

-- flags --
-mcp

-- settings.json --
{
    "mcpTools": {
        "go_file_metadata": true
    }
}
-- go.mod --
module example.com/cmd

go 1.21

-- main.go --
package main

//@mcptool("go_file_metadata", `{"file":"$WORKDIR/main.go"}`, output=metadata)

func main() {

}
-- @metadata --
File `$WORKDIR/main.go` is in package "example.com/cmd", which has the following files:
	$WORKDIR/main.go


================================================
FILE: gopls/internal/test/marker/testdata/mcptools/package_api.txt
================================================
This test exercises the "go_package_api" MCP tool.

-- flags --
-mcp

-- go.mod --
module example.com/mod

//@mcptool("go_package_api", `{"packagePaths":["example.com/mod/lib"]}`, output=outline)

go 1.21

-- main.go --
package main

import "example.com/mod/lib"

func main() {
	println(lib.Foo(0))
}
-- lib/lib.go --
package lib

type T int

func Foo(int) string {
	return ""
}

-- lib/lib_test.go --
package lib

import "testing"

func Test(*testing.T) {
}

-- @outline --
"example.com/mod/lib" (package lib)
lib.go:
```go
package lib

type T int

func Foo(int) string

```



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/references.txt
================================================
This test exercises the "go_references" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

-- settings.json --
{
    "mcpTools": {
        "go_references": true
    }
}

-- a/a.go --
package a

func Foo() {} //@loc(Foo, "Foo")

func callFoo() {
    Foo()
}

-- b/b.go --
package b

import "example.com/a"

func callFoo() {
    a.Foo()
}

//@mcptool("go_references", `{}`, location=Foo, output=threeref)

-- @threeref --
The object has 3 references. Their locations are listed below
Reference 1
Located in the file: $WORKDIR/a/a.go
The reference is located on line 2, which has content `func Foo() {} //@loc(Foo, "Foo")`

Reference 2
Located in the file: $WORKDIR/a/a.go
The reference is located on line 5, which has content `Foo()`

Reference 3
Located in the file: $WORKDIR/b/b.go
The reference is located on line 5, which has content `a.Foo()`



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/rename_symbol.txt
================================================
This test exercises the "go_rename_symbol" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

//@mcptool("go_rename_symbol", `{"file":"$WORKDIR/a/a.go","symbol":"Foo", "new_name": "Bar"}`, output=aFoo)
//@mcptool("go_rename_symbol", `{"file":"$WORKDIR/a/a.go","symbol":"NonExistent", "new_name": "Bar"}`, output=aErr)

-- a/a.go --
package a

func Foo() {}

func callFoo() {
    Foo()
}

-- @aFoo --
The following changes are necessary to rename the symbol:
--- $WORKDIR/a/a.go
+++ $WORKDIR/a/a.go
@@ -1,8 +1,8 @@
 package a
 
-func Foo() {}
+func Bar() {}
 
 func callFoo() {
-    Foo()
+    Bar()
 }
 


-- @aErr --
failed to resolve name "NonExistent"


================================================
FILE: gopls/internal/test/marker/testdata/mcptools/search.txt
================================================
This test exercises the "go_search" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

go 1.21

//@mcptool("go_search", `{"query": "foo"}`, output=foo)
//@mcptool("go_search", `{"query": "bar"}`, output=bar)
//@mcptool("go_search", `{"query": "baz"}`, output=baz)

-- main.go --
package main

import (
	"example.com/a"
	"example.com/b"
)

func FOO() {}

type baz int

func main() {
	println(a.Foo + b.Ar)
}
-- a/a.go --
package a

const (
	Foo = 1
	Bar = 2
)

type B struct {
	ar string
}

-- b/b.go --
package b

const (
	aZ = 1
	Ar = 2
)

var fOo = 3

-- @foo --
Top symbol matches:
	FOO (Function in `$WORKDIR/main.go`)
	Foo (Constant in `$WORKDIR/a/a.go`)
	fOo (Variable in `$WORKDIR/b/b.go`)
-- @bar --
Top symbol matches:
	Bar (Constant in `$WORKDIR/a/a.go`)
	b.Ar (Constant in `$WORKDIR/b/b.go`)
	B.ar (Field in `$WORKDIR/a/a.go`)
-- @baz --
Top symbol matches:
	baz (Type in `$WORKDIR/main.go`)
	b.aZ (Constant in `$WORKDIR/b/b.go`)


================================================
FILE: gopls/internal/test/marker/testdata/mcptools/symbol_references.txt
================================================
This test exercises the "go_symbol_references" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

// TODO(rfindley): add error assertions here.

//@mcptool("go_symbol_references", `{"file":"$WORKDIR/a/a.go","symbol":"Foo"}`, output=aFoo)
//@mcptool("go_symbol_references", `{"file":"$WORKDIR/b/b.go","symbol":"a.Foo"}`, output=aFoo)
//@mcptool("go_symbol_references", `{"file":"$WORKDIR/a/a.go","symbol":"T.Bar"}`, output=aBar)
//@mcptool("go_symbol_references", `{"file":"$WORKDIR/b/b.go","symbol":"a.T.Bar"}`, output=aBar)

-- a/a.go --
package a

func Foo() {}

func callFoo() {
    Foo()
}

type T int

func (T) Bar() {}

-- b/b.go --
package b

import "example.com/a"

func callFoo() {
    a.Foo()
}

-- @aFoo --
The object has 3 references. Their locations are listed below
Reference 1
Located in the file: $WORKDIR/a/a.go
The reference is located on line 2, which has content `func Foo() {}`

Reference 2
Located in the file: $WORKDIR/a/a.go
The reference is located on line 5, which has content `Foo()`

Reference 3
Located in the file: $WORKDIR/b/b.go
The reference is located on line 5, which has content `a.Foo()`

-- @aBar --
The object has 1 references. Their locations are listed below
Reference 1
Located in the file: $WORKDIR/a/a.go
The reference is located on line 10, which has content `func (T) Bar() {}`



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/workspace.txt
================================================
This test exercises the "go_workspace" MCP tool.

-- flags --
-mcp
-min_go_command=go1.23

-- go.work --
go 1.23.0

//@mcptool("go_workspace", `{}`, output=workspace)

use (
	./a
	./b
)

-- a/go.mod --
module example.com/a

go 1.23.0

-- a/a.go --
package a

-- b/go.mod --
module example.com/b

go 1.23.0

-- b/b.go --
package b

-- @workspace --
The `$WORKDIR` directory is in the go workspace defined by `$WORKDIR/go.work`, with the following main modules:
	$WORKDIR/a/go.mod (module example.com/a)
	$WORKDIR/b/go.mod (module example.com/b)



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/workspace_diagnostics.txt
================================================
This test exercises the "go_diagnostics" MCP tool.

-- flags --
-mcp
-ignore_extra_diags

-- go.mod --
module example.com

go 1.21

//@mcptool("go_diagnostics", `{"files":["$WORKDIR/a/a.go"]}`, output=diagnostics)
//@mcptool("go_diagnostics", `{"files":["$WORKDIR/b/b.go"]}`, output=diagnostics)
//@mcptool("go_diagnostics", `{"files":["$WORKDIR/main.go"]}`, output=diagnostics)

-- main.go --
package main

import (
	"example.com/a"
	"example.com/b"
)

func main() int {
	a.Print(b.B)
	return 0
}

-- a/a.go --
package a

func Print(x string) {
	println(x)
}

-- b/b.go --
package b

const B = 1

-- b/b2.go --

const B = 2

-- @diagnostics --
File `$WORKDIR/b/b2.go` has the following diagnostics:
1:0-1:0: [Error] expected 'package', found 'const'

File `$WORKDIR/main.go` has the following diagnostics:
7:5-7:9: [Error] func main must have no arguments and no return values
8:9-8:12: [Error] cannot use b.B (untyped int constant 1) as string value in argument to a.Print



================================================
FILE: gopls/internal/test/marker/testdata/mcptools/workspace_diagnostics_empty.txt
================================================
This test exercises the "go_diagnostics" MCP tool.

-- flags --
-mcp

-- go.mod --
module example.com

go 1.21

//@mcptool("go_diagnostics", `{"files":["$WORKDIR/main.go"]}`, output=diagnostics)
//@mcptool("go_diagnostics", `{"files":[]}`, output=diagnostics)
//@mcptool("go_diagnostics", `{}`, output=diagnostics)

-- main.go --
package main

func main() {
	println("Hello world")
}

-- @diagnostics --
No diagnostics.


================================================
FILE: gopls/internal/test/marker/testdata/modfile/godebug.txt
================================================
This test basic gopls functionality in a workspace with a godebug
directive in its modfile.

We use panicnil from go1.21 as an arbitrary GODEBUG; if it goes away,
pick another from https://go.dev/doc/godebug#history.

-- flags --
-min_go_command=go1.23

-- go.mod --
module example.com/m

go 1.23

godebug (
	panicnil=0
)
godebug panicnil=1

-- a/a.go --
package a

import "example.com/m/b"

const A = b.B //@def("B", B)

-- b/b.go --
package b

const B = 42 //@loc(B, "B")

-- format/go.mod --
module example.com/m/format //@format(formatted)

godebug (
panicnil=0
)
godebug      panicnil=1
-- @formatted --
module example.com/m/format //@format(formatted)

godebug (
	panicnil=0
)

godebug panicnil=1


================================================
FILE: gopls/internal/test/marker/testdata/modfile/godebug_bad.txt
================================================
This test checks that we surface the error for unexpected godebug values.

TODO(golang/go#67623): the diagnostic should be on the bad godebug value.

-- flags --
-min_go_command=go1.23
-errors_ok

-- go.mod --
module example.com/m //@diag("module", re`unknown godebug "panicnull"`)

go 1.23

godebug (
	panicnull=0 // misspelled
)
godebug panicnil=1


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/embeddirective.txt
================================================
This test checks the quick fix to add a missing "embed" import.

-- embed.txt --
text
-- fix_import.go --
package embeddirective

import (
	"io"
	"os"
)

//go:embed embed.txt //@quickfix("//go:embed", re`must import "embed"`, fix_import)
var T string

func _() {
	_ = os.Stdin
	_ = io.EOF
}
-- @fix_import/fix_import.go --
@@ -4 +4 @@
+	_ "embed"


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/infertypeargs.txt
================================================
This test verifies the infertypeargs refactoring.

-- go.mod --
module mod.test/infertypeargs

go 1.18

-- p.go --
package infertypeargs

func app[S interface{ ~[]E }, E any](s S, e E) S {
	return append(s, e)
}

func _() {
	_ = app[[]int]
	_ = app[[]int, int]
	_ = app[[]int]([]int{}, 0) //@quickfix("[[]int]", re"unnecessary type arguments", infer)
	_ = app([]int{}, 0)
}

-- @infer/p.go --
@@ -10 +10 @@
-	_ = app[[]int]([]int{}, 0) //@quickfix("[[]int]", re"unnecessary type arguments", infer)
+	_ = app([]int{}, 0) //@quickfix("[[]int]", re"unnecessary type arguments", infer)


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/issue65024.txt
================================================
Regression example.com for #65024, "incorrect package qualification when
stubbing method in v2 module".

The second test (a-a) ensures that we don't use path-based heuristics
to guess the PkgName of an import.

-- a/v2/go.mod --
module example.com/a/v2
go 1.18

-- a/v2/a.go --
package a

type I interface { F() T }

type T struct {}

-- a/v2/b/b.go --
package b

import "example.com/a/v2"

type B struct{}

var _ a.I = &B{} //@ quickfix("&B{}", re"does not implement", out)

// This line makes the diff tidier.

-- @out/a/v2/b/b.go --
@@ -7 +7,5 @@
+// F implements [a.I].
+func (b *B) F() a.T {
+	panic("unimplemented")
+}
+
@@ -10 +15 @@
-
-- a-a/v2/go.mod --
// This module has a hyphenated name--how posh.
// It won't do to use it as an identifier.
// The correct name is the one in the package decl,
// which in this case is not what the path heuristic would guess.
module example.com/a-a/v2
go 1.18

-- a-a/v2/a.go --
package a
type I interface { F() T }
type T struct {}

-- a-a/v2/b/b.go --
package b

// Note: no existing import of a.

type B struct{}

var _ I = &B{} //@ quickfix("&B{}", re"does not implement", out2)

// This line makes the diff tidier.

-- a-a/v2/b/import-a-I.go --
package b
import "example.com/a-a/v2"
type I = a.I

-- @out2/a-a/v2/b/b.go --
@@ -3 +3,2 @@
+import a "example.com/a-a/v2"
+
@@ -7 +9,5 @@
+// F implements [a.I].
+func (b *B) F() a.T {
+	panic("unimplemented")
+}
+
@@ -10 +17 @@
-


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/noresultvalues.txt
================================================
This test checks the quick fix for removing extra return values.

Note: gopls should really discard unnecessary return statements.

-- noresultvalues.go --
package typeerrors

func x() { return nil } //@quickfix("nil", re"too many return", x)

func y() { return nil, "hello" } //@quickfix("nil", re"too many return", y)
-- @x/noresultvalues.go --
@@ -3 +3 @@
-func x() { return nil } //@quickfix("nil", re"too many return", x)
+func x() { return } //@quickfix("nil", re"too many return", x)
-- @y/noresultvalues.go --
@@ -5 +5 @@
-func y() { return nil, "hello" } //@quickfix("nil", re"too many return", y)
+func y() { return } //@quickfix("nil", re"too many return", y)


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/self_assignment.txt
================================================
Test of the suggested fix to remove unnecessary assignments.

-- a.go --
package quickfix

import (
	"log"
)

func _() {
	s := "hiiiiiii"
	s = s //@quickfix("s = s", re"self-assignment", fix)
	log.Print(s)
}

-- @fix/a.go --
@@ -9 +9 @@
-	s = s //@quickfix("s = s", re"self-assignment", fix)


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stub.txt
================================================
This test checks the 'implement interface' quick fix.

-- go.mod --
module golang.org/lsptests/stub

go 1.18

-- other/other.go --
package other

import (
	"bytes"
	renamed_context "context"
)

type Interface interface {
	Get(renamed_context.Context) *bytes.Buffer
}

-- add_selector.go --
package stub

import "io"

// This file tests that if an interface
// method references a type from its own package
// then our implementation must add the import/package selector
// in the concrete method if the concrete type is outside of the interface
// package
var _ io.ReaderFrom = &readerFrom{} //@quickfix("&readerFrom", re"cannot use", readerFrom)

type readerFrom struct{}
-- @readerFrom/add_selector.go --
@@ -13 +13,5 @@
+
+// ReadFrom implements [io.ReaderFrom].
+func (*readerFrom) ReadFrom(r io.Reader) (n int64, err error) {
+	panic("unimplemented")
+}
-- assign.go --
package stub

import "io"

func _() {
	var br io.ByteWriter
	br = &byteWriter{} //@quickfix("&", re"does not implement", assign)
	_ = br
}

type byteWriter struct{}
-- @assign/assign.go --
@@ -12 +12,5 @@
+
+// WriteByte implements [io.ByteWriter].
+func (b *byteWriter) WriteByte(c byte) error {
+	panic("unimplemented")
+}
-- assign_multivars.go --
package stub

import "io"

func _() {
	var br io.ByteWriter
	var i int
	i, br = 1, &multiByteWriter{} //@quickfix("&", re"does not implement", assign_multivars)
	_, _ = i, br
}

type multiByteWriter struct{}
-- @assign_multivars/assign_multivars.go --
@@ -13 +13,5 @@
+
+// WriteByte implements [io.ByteWriter].
+func (m *multiByteWriter) WriteByte(c byte) error {
+	panic("unimplemented")
+}
-- call_expr.go --
package stub

func main() {
	check(&callExpr{}) //@quickfix("&", re"does not implement", call_expr)
}

func check(err error) {
	if err != nil {
		panic(err)
	}
}

type callExpr struct{}
-- @call_expr/call_expr.go --
@@ -14 +14,5 @@
+
+// Error implements [error].
+func (c *callExpr) Error() string {
+	panic("unimplemented")
+}
-- embedded.go --
package stub

import (
	"io"
	"sort"
)

var _ embeddedInterface = (*embeddedConcrete)(nil) //@quickfix("(", re"does not implement", embedded)

type embeddedConcrete struct{}

type embeddedInterface interface {
	sort.Interface
	io.Reader
}
-- @embedded/embedded.go --
@@ -12 +12,20 @@
+// Len implements [embeddedInterface].
+func (e *embeddedConcrete) Len() int {
+	panic("unimplemented")
+}
+
+// Less implements [embeddedInterface].
+func (e *embeddedConcrete) Less(i int, j int) bool {
+	panic("unimplemented")
+}
+
+// Read implements [embeddedInterface].
+func (e *embeddedConcrete) Read(p []byte) (n int, err error) {
+	panic("unimplemented")
+}
+
+// Swap implements [embeddedInterface].
+func (e *embeddedConcrete) Swap(i int, j int) {
+	panic("unimplemented")
+}
+
-- err.go --
package stub

func _() {
	var br error = &customErr{} //@quickfix("&", re"does not implement", err)
	_ = br
}

type customErr struct{}
-- @err/err.go --
@@ -9 +9,5 @@
+
+// Error implements [error].
+func (c *customErr) Error() string {
+	panic("unimplemented")
+}
-- function_return.go --
package stub

import (
	"io"
)

func newCloser() io.Closer {
	return closer{} //@quickfix("c", re"does not implement", function_return)
}

type closer struct{}
-- @function_return/function_return.go --
@@ -12 +12,5 @@
+
+// Close implements [io.Closer].
+func (c closer) Close() error {
+	panic("unimplemented")
+}
-- successive_function_return.go --
package stub

import (
	"io"
)

func _() (a, b int, c io.Closer) {
	return 1, 2, closer2{} //@quickfix("c", re"does not implement", successive)
}

type closer2 struct{}
-- @successive/successive_function_return.go --
@@ -12 +12,5 @@
+
+// Close implements [io.Closer].
+func (c closer2) Close() error {
+	panic("unimplemented")
+}
-- generic_receiver.go --
package stub

import "io"

// This file tests that the stub method generator accounts for concrete
// types that have type parameters defined.
var _ io.ReaderFrom = &genReader[string, int]{} //@quickfix("&genReader", re"does not implement", generic_receiver)

type genReader[T, Y any] struct {
	T T
	Y Y
}
-- @generic_receiver/generic_receiver.go --
@@ -13 +13,5 @@
+
+// ReadFrom implements [io.ReaderFrom].
+func (g *genReader[T, Y]) ReadFrom(r io.Reader) (n int64, err error) {
+	panic("unimplemented")
+}
-- ignored_imports.go --
package stub

import (
	"compress/zlib"
	. "io"
	_ "io"
)

// This file tests that dot-imports and underscore imports
// are properly ignored and that a new import is added to
// reference method types

var (
	_ Reader
	_ zlib.Resetter = (*ignoredResetter)(nil) //@quickfix("(", re"does not implement", ignored_imports)
)

type ignoredResetter struct{}
-- @ignored_imports/ignored_imports.go --
@@ -19 +19,5 @@
+
+// Reset implements [zlib.Resetter].
+func (i *ignoredResetter) Reset(r Reader, dict []byte) error {
+	panic("unimplemented")
+}
-- issue2606.go --
package stub

type I interface{ error }

type C int

var _ I = C(0) //@quickfix("C", re"does not implement", issue2606)
-- @issue2606/issue2606.go --
@@ -7 +7,5 @@
+// Error implements [I].
+func (c C) Error() string {
+	panic("unimplemented")
+}
+
-- multi_var.go --
package stub

import "io"

// This test ensures that a variable declaration that
// has multiple values on the same line can still be
// analyzed correctly to target the interface implementation
// diagnostic.
var one, two, three io.Reader = nil, &multiVar{}, nil //@quickfix("&", re"does not implement", multi_var)

type multiVar struct{}
-- @multi_var/multi_var.go --
@@ -12 +12,5 @@
+
+// Read implements [io.Reader].
+func (m *multiVar) Read(p []byte) (n int, err error) {
+	panic("unimplemented")
+}
-- pointer.go --
package stub

import "io"

func getReaderFrom() io.ReaderFrom {
	return &pointerImpl{} //@quickfix("&", re"does not implement", pointer)
}

type pointerImpl struct{}
-- @pointer/pointer.go --
@@ -10 +10,5 @@
+
+// ReadFrom implements [io.ReaderFrom].
+func (p *pointerImpl) ReadFrom(r io.Reader) (n int64, err error) {
+	panic("unimplemented")
+}
-- renamed_import.go --
package stub

import (
	"compress/zlib"
	myio "io"
)

var _ zlib.Resetter = &myIO{} //@quickfix("&", re"does not implement", renamed_import)
var _ myio.Reader

type myIO struct{}
-- @renamed_import/renamed_import.go --
@@ -12 +12,5 @@
+
+// Reset implements [zlib.Resetter].
+func (m *myIO) Reset(r myio.Reader, dict []byte) error {
+	panic("unimplemented")
+}
-- renamed_import_iface.go --
package stub

import (
	"golang.org/lsptests/stub/other"
)

// This file tests that if an interface
// method references an import from its own package
// that the concrete type does not yet import, and that import happens
// to be renamed, then we prefer the renaming of the interface.
var _ other.Interface = &otherInterfaceImpl{} //@quickfix("&otherInterfaceImpl", re"does not implement", renamed_import_iface)

type otherInterfaceImpl struct{}
-- @renamed_import_iface/renamed_import_iface.go --
@@ -4 +4,2 @@
+	"bytes"
+	"context"
@@ -14 +16,5 @@
+
+// Get implements [other.Interface].
+func (o *otherInterfaceImpl) Get(context.Context) *bytes.Buffer {
+	panic("unimplemented")
+}
-- stdlib.go --
package stub

import (
	"io"
)

var _ io.Writer = writer{} //@quickfix("w", re"does not implement", stdlib)

type writer struct{}
-- @stdlib/stdlib.go --
@@ -10 +10,5 @@
+
+// Write implements [io.Writer].
+func (w writer) Write(p []byte) (n int, err error) {
+	panic("unimplemented")
+}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/basic.txt
================================================
This test exercises basic 'stub methods' functionality.
See basic_resolve.txt for the same test with resolve support.

-- capabilities.json --
{
	"textDocument": {
		"codeAction": {
			"dataSupport": false,
			"resolveSupport": {}
		}
	}
}

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type C int

var _ error = C(0) //@quickfix(re"C.0.", re"missing method Error", stub)
-- @stub/a/a.go --
@@ -5 +5,5 @@
+// Error implements [error].
+func (c C) Error() string {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/basic_resolve.txt
================================================
This test exercises basic 'stub methods' functionality, with resolve support.
See basic.txt for the same test without resolve support.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type C int

var _ error = C(0) //@quickfix(re"C.0.", re"missing method Error", stub)
-- @stub/a/a.go --
@@ -5 +5,5 @@
+// Error implements [error].
+func (c C) Error() string {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/fromcall_basic.txt
================================================
This test checks the basic of 'Declare missing method T.f' quick fix.

-- basic_stub.go --
package fromcallbasic

type Basic struct{}

func basic() {
	i := 1
	b := Basic{}
	f(b.basic(i)) //@quickfix("basic", re"has no field or method", basic)
}

func f(i int) string { return "s" }
-- @basic/basic_stub.go --
@@ -5 +5,4 @@
+func (b Basic) basic(i int) int {
+	panic("unimplemented")
+}
+
-- pointer.go --
package fromcallbasic

type P struct{}

func recv_param_pointer() {
	p := &P{}
	i := 42
	p.pointer(&i) //@quickfix("pointer", re"has no field or method", pointer)
}
-- @pointer/pointer.go --
@@ -5 +5,4 @@
+func (p *P) pointer(i *int) {
+	panic("unimplemented")
+}
+
-- other.go --
package fromcallbasic

type TypeDeclInOtherFile struct{}

-- this.go --
package fromcallbasic

func fun() {
	i := 1
	t := TypeDeclInOtherFile{}
	t.other(i) //@quickfix("other", re"has no field or method", del_other)
}
-- @del_other/other.go --
@@ -5 +5,3 @@
+func (t TypeDeclInOtherFile) other(i int) {
+	panic("unimplemented")
+}
-- should_insert_after.go --
package fromcallbasic

type HasMethod struct{}

func (h *HasMethod) m() {
	h.should_insert_after() //@quickfix("should_insert_after", re"has no field or method", insert)
}
-- @insert/should_insert_after.go --
@@ -8 +8,4 @@
+
+func (h *HasMethod) should_insert_after() {
+	panic("unimplemented")
+}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/fromcall_params.txt
================================================
This test checks the param name and type of the generated missing method based on CallExpr.

-- basic_stub.go --
package fromcallparams

type A struct{}

func untypedParams() {
	a := A{}
	a.untyped("s", 42, 4.12, make(map[string]int), []int{1}, [1]int{1}, make(chan string)) //@quickfix("untyped", re"has no field or method", basic)
}
-- @basic/basic_stub.go --
@@ -5 +5,4 @@
+func (a A) untyped(s string, i int, f float64, m map[string]int, param5 []int, param6 [1]int, ch chan string) {
+	panic("unimplemented")
+}
+
-- nonexistent_type.go --
package fromcallparams

type B struct{}

func invalidBasicKindParam() {
	b := B{}
	b.basicKind(NonExistentType{}) //@quickfix("basicKind", re"has no field or method", nonexistent),diag(re"NonExistentType",re"undefined: NonExistentType")
}
-- @nonexistent/nonexistent_type.go --
@@ -5 +5,4 @@
+func (b B) basicKind(param any) {
+	panic("unimplemented")
+}
+
-- pass_param_by_ident.go --
package fromcallparams

type C struct{}

func passParamByIdent() {
	c := C{}
	stringVar := "some string"
	intVar := 1
	sliceVar := []int{1}
	c.ident(stringVar, intVar, sliceVar) //@quickfix("ident", re"has no field or method", ident)
}
-- @ident/pass_param_by_ident.go --
@@ -5 +5,4 @@
+func (c C) ident(stringVar string, intVar int, sliceVar []int) {
+	panic("unimplemented")
+}
+
-- tail_param_name.go --
package fromcallparams

type Tail struct{}

type TypeWithLongName struct{}

func TailParamName() {
	t := Tail{}
	t.longName(TypeWithLongName{}) //@quickfix("longName", re"has no field or method", trail)
}
-- @trail/tail_param_name.go --
@@ -5 +5,4 @@
+func (t Tail) longName(name TypeWithLongName) {
+	panic("unimplemented")
+}
+
-- selector_param_name.go --
package fromcallparams

import "net/http"

type Select struct{}

func selectExpr() {
	s := Select{}
	s.sel(http.ErrNotMultipart) //@quickfix("sel", re"has no field or method", select)
}
-- @select/selector_param_name.go --
@@ -7 +7,4 @@
+func (s Select) sel(multipart *http.ProtocolError) {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/fromcall_returns.txt
================================================
This test checks the return type of the generated missing method based on CallExpr.

-- param.go --
package fromcallreturns

type A struct{}

func inferFromParam() {
	a := A{}
	f(a.as_param()) //@quickfix("as_param", re"has no field or method", infer_param)
}

func f(i int) {}
-- @infer_param/param.go --
@@ -5 +5,4 @@
+func (a A) as_param() int {
+	panic("unimplemented")
+}
+
-- assign.go --
package fromcallreturns

type Assign struct{}

func inferReturnfromAssign() {
	var assign int //@diag("assign",re"not used")
	a := Assign{}
	assign = a.as_assign() //@quickfix("as_assign", re"has no field or method", infer_assign)
}
-- @infer_assign/assign.go --
@@ -5 +5,4 @@
+func (a Assign) as_assign() int {
+	panic("unimplemented")
+}
+
-- multiple_assign.go --
package fromcallreturns

type MultiAssign struct{}

func inferReturnfromMultipleAssign() {
	var assign1 int //@diag("assign1",re"not used")
	var assign2 int //@diag("assign2",re"not used")
	m := MultiAssign{}
	assign1, assign2 = m.multi_assign() //@quickfix("multi_assign", re"has no field or method", infer_multiple_assign)
}
-- @infer_multiple_assign/multiple_assign.go --
@@ -5 +5,4 @@
+func (m MultiAssign) multi_assign() (int, int) {
+	panic("unimplemented")
+}
+
-- multiple_return_in_param.go --
package fromcallreturns

type MultiReturn struct{}

func inferMultipleReturnInParam() {
	m := MultiReturn{}
	m.param_has_multi_return(multiReturn()) //@quickfix("param_has_multi_return", re"has no field or method", multiple_return)
}

func multiReturn() (int, int) {
	return 1, 1
}
-- @multiple_return/multiple_return_in_param.go --
@@ -5 +5,4 @@
+func (m MultiReturn) param_has_multi_return(i int, param2 int) {
+	panic("unimplemented")
+}
+
-- error_nodes.go --
package fromcallreturns

type E struct{}

func all_error() {
	e := E{}
	errorFunc(e.errors(undefined1(), undefined2(), undefined3{})) //@quickfix("errors", re"has no field or method", all_error),diag("undefined1",re"undefined"),diag("undefined2",re"undefined"),diag("undefined3",re"undefined")
}
func errorFunc(u undefined4) {} //@diag("undefined4",re"undefined")
-- @all_error/error_nodes.go --
@@ -5 +5,4 @@
+func (e E) errors(param any, param2 any, param3 any) any {
+	panic("unimplemented")
+}
+
-- paren.go --
package fromcallreturns

type Paren struct{}

func paren() {
	p := Paren{}
	fn()((p.surroundingParen())) //@quickfix("surroundingParen", re"has no field or method", surrounding_paren)
}

func fn() func(i int) {
	return func(i int) {}
}
-- @surrounding_paren/paren.go --
@@ -5 +5,4 @@
+func (p Paren) surroundingParen() int {
+	panic("unimplemented")
+}
+
-- if_stmt.go --
package fromcallreturns

type IfStruct struct{}

func testIfStmt() {
	i := IfStruct{}
	if i.isValid() { //@quickfix("isValid", re"has no field or method", infer_if_stmt)
		// do something
	}
}
-- @infer_if_stmt/if_stmt.go --
@@ -5 +5,4 @@
+func (i IfStruct) isValid() bool {
+	panic("unimplemented")
+}
+
-- for_stmt.go --
package fromcallreturns

type ForStruct struct{}

func testForStmt() {
	f := ForStruct{}
	for f.hasNext() { //@quickfix("hasNext", re"has no field or method", infer_for_stmt1)
		// do something
	}
	for i := 0; f.inside(); i++ { //@quickfix("inside", re"has no field or method", infer_for_stmt2)
		// do something
	}
}
-- @infer_for_stmt1/for_stmt.go --
@@ -5 +5,4 @@
+func (f ForStruct) hasNext() bool {
+	panic("unimplemented")
+}
+
-- @infer_for_stmt2/for_stmt.go --
@@ -5 +5,4 @@
+func (f ForStruct) inside() bool {
+	panic("unimplemented")
+}
+
-- unary.go --
package fromcallreturns

type Unary struct{}

func testUnaryExpr() {
	u := Unary{}
	a, b, c, d := !u.Boolean(), -u.Minus(), +u.Plus(), ^u.Xor() //@quickfix("Boolean", re"has no field or method", infer_unary_expr1),quickfix("Minus", re"has no field or method", infer_unary_expr2),quickfix("Plus", re"has no field or method", infer_unary_expr3),quickfix("Xor", re"has no field or method", infer_unary_expr4)
	_, _, _, _ = a, b, c, d
}
-- @infer_unary_expr1/unary.go --
@@ -5 +5,4 @@
+func (u Unary) Boolean() bool {
+	panic("unimplemented")
+}
+
-- @infer_unary_expr2/unary.go --
@@ -5 +5,4 @@
+func (u Unary) Minus() int {
+	panic("unimplemented")
+}
+
-- @infer_unary_expr3/unary.go --
@@ -5 +5,4 @@
+func (u Unary) Plus() int {
+	panic("unimplemented")
+}
+
-- @infer_unary_expr4/unary.go --
@@ -5 +5,4 @@
+func (u Unary) Xor() int {
+	panic("unimplemented")
+}
+
-- binary.go --
package fromcallreturns

type Binary struct{}

func testBinaryExpr() {
	b := Binary{}
	_ = 1 + b.Num()   //@quickfix("Num", re"has no field or method", infer_binary_expr1)
	_ = "s" + b.Str() //@quickfix("Str", re"has no field or method", infer_binary_expr2)
}
-- @infer_binary_expr1/binary.go --
@@ -5 +5,4 @@
+func (b Binary) Num() int {
+	panic("unimplemented")
+}
+
-- @infer_binary_expr2/binary.go --
@@ -5 +5,4 @@
+func (b Binary) Str() string {
+	panic("unimplemented")
+}
+
-- value.go --
package fromcallreturns

type Value struct{}

func v() {
	v := Value{}
	var a, b int = v.Multi()     //@quickfix("Multi", re"has no field or method", infer_value_expr1)
	var c, d int = 4, v.Single() //@quickfix("Single", re"has no field or method", infer_value_expr2)
	_, _, _, _ = a, b, c, d
}
-- @infer_value_expr1/value.go --
@@ -5 +5,4 @@
+func (v Value) Multi() (int, int) {
+	panic("unimplemented")
+}
+
-- @infer_value_expr2/value.go --
@@ -5 +5,4 @@
+func (v Value) Single() int {
+	panic("unimplemented")
+}
+
-- return.go --
package fromcallreturns

type Return struct{}

func r() {
	r := Return{}
	_ = func() (int, int) {
		return r.Multi() //@quickfix("Multi", re"has no field or method", infer_retrun_expr1)
	}
	_ = func() string {
		return r.Single() //@quickfix("Single", re"has no field or method", infer_retrun_expr2)
	}
}
-- @infer_retrun_expr1/return.go --
@@ -5 +5,4 @@
+func (r Return) Multi() (int, int) {
+	panic("unimplemented")
+}
+
-- @infer_retrun_expr2/return.go --
@@ -5 +5,4 @@
+func (r Return) Single() string {
+	panic("unimplemented")
+}
+
-- successive_return.go --
package fromcallreturns

type R struct{}

func _() (x int, y, z string, k int64) {
	r := R{}
	_ = func() (a, b float32, c int) {
		return r.Multi() //@quickfix("Multi", re"has no field or method", successive1)
	}
	return 3, "", r.Single(), 6 //@quickfix("Single", re"has no field or method", successive2)
}
-- @successive1/successive_return.go --
@@ -5 +5,4 @@
+func (r R) Multi() (float32, float32, int) {
+	panic("unimplemented")
+}
+
-- @successive2/successive_return.go --
@@ -5 +5,4 @@
+func (r R) Single() string {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/issue61693.txt
================================================
This test exercises stub methods functionality with variadic parameters.

In golang/go#61693 stubmethods was panicking in this case.

-- go.mod --
module mod.com

go 1.18
-- main.go --
package main

type C int

func F(err ...error) {}

func _() {
	var x error
	F(x, C(0)) //@quickfix(re"C.0.", re"missing method Error", stub)
}
-- @stub/main.go --
@@ -5 +5,5 @@
+// Error implements [error].
+func (c C) Error() string {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/issue61830.txt
================================================
This test verifies that method stubbing qualifies types relative to the current
package.

-- p.go --
package p

import "io"

type B struct{}

type I interface {
	M(io.Reader, B)
}

type A struct{}

var _ I = &A{} //@quickfix(re"&A..", re"missing method M", stub)
-- @stub/p.go --
@@ -13 +13,5 @@
+// M implements [I].
+func (a *A) M(io.Reader, B) {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/issue64078.txt
================================================
This test verifies that the named receiver is generated.

-- p.go --
package p

type A struct{}

func (aa *A) M1() {
	panic("unimplemented")
}

type I interface {
	M1()
	M2(aa string)
	M3(bb string)
	M4() (aa string)
}

var _ I = &A{} //@quickfix(re"&A..", re"missing method M", stub)
-- @stub/p.go --
@@ -5 +5,15 @@
+// M2 implements [I].
+func (*A) M2(aa string) {
+	panic("unimplemented")
+}
+
+// M3 implements [I].
+func (aa *A) M3(bb string) {
+	panic("unimplemented")
+}
+
+// M4 implements [I].
+func (*A) M4() (aa string) {
+	panic("unimplemented")
+}
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/issue64114.txt
================================================
This test verifies that the embedded field has a method with the same name.

-- issue64114.go --
package stub

// Regression test for issue #64114: code action "implement" is not listed.

var _ WriteTest = (*WriteStruct)(nil) //@quickfix("(", re"does not implement", issue64114)

type WriterTwoStruct struct{}

// Write implements [io.ReadWriter].
func (t *WriterTwoStruct) RRRR(str string) error {
	panic("unimplemented")
}

type WriteTest interface {
	RRRR()
	WWWW()
}

type WriteStruct struct {
	WriterTwoStruct
}
-- @issue64114/issue64114.go --
@@ -22 +22,5 @@
+
+// WWWW implements [WriteTest].
+func (w *WriteStruct) WWWW() {
+	panic("unimplemented")
+}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/shadowedmethods.txt
================================================
This test exercises verifies that the stubmethods quickfix does not shadow existing methods.
See golang/go#77130.

-- go.mod --
module mod.com

go 1.22

-- main.go --
package main

type I interface {
	Foo()
	Bar()
}

type B struct {
	*A
}

type A struct {
}

func (a *A) Foo() {
}

// Interface I requires implementing Foo() and Bar(). B embeds A, and A already
// implements Foo. To avoid method shadowing, the stub for B should only
// implement Bar and not Foo.
var _ I = (*B)(nil) //@quickfix(re"..B..nil.", re"missing method", stub)

-- @stub/main.go --
@@ -12 +12,5 @@
+// Bar implements [I].
+func (b *B) Bar() {
+	panic("unimplemented")
+}
+
@@ -22 +27 @@
-


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/stubmethods/stuberrors.txt
================================================
This test verifies two types of errors when generating interface method stubs:
1. adding method __ would conflict with (or shadow) existing field
2. method __ already exists but has the wrong type

-- go.mod --
module mod.com

go 1.22

-- wrong/type.go --
package wrongtype

type I interface {
	Foo()
	Bar()
}

type B struct {
	*A
}

type A struct {}

func (a *A) Foo() {}
func (b *B) Foo(bool) {} // method Foo exists on B but has the wrong type

var _ I = (*B)(nil) //@quickfixerr(re"..B..nil.", re"missing method", "already exists but has the wrong type")

-- field/conflict.go --
package fieldconflict

type I interface {
	Foo()
	Bar()
}

type B struct {
	*A
}

type A struct {
    Bar int // implementing a method "Bar" would conflict with existing field "Bar"
}

func (a *A) Foo() {}
var _ I = (*B)(nil) //@quickfixerr(re"..B..nil.", re"is a field, not a method", "would conflict with (or shadow) existing field")



================================================
FILE: gopls/internal/test/marker/testdata/quickfix/undeclared/diag.txt
================================================
This test checks @diag reports for undeclared variables and functions.

-- x.go --
package undeclared

func x() int {
	var z int
	z = y //@diag("y", re"(undeclared name|undefined): y")
	if z == m { //@diag("m", re"(undeclared name|undefined): m")
		z = 1
	}

	if z == 1 {
		z = 1
	} else if z == n+1 { //@diag("n", re"(undeclared name|undefined): n")
		z = 1
	}

	switch z {
	case 10:
		z = 1
	case aa: //@diag("aa", re"(undeclared name|undefined): aa")
		z = 1
	}
	return z
}
-- channels.go --
package undeclared

func channels(s string) {
	undefinedChannels(c()) //@diag("undefinedChannels", re"(undeclared name|undefined): undefinedChannels")
}

func c() (<-chan string, chan string) {
	return make(<-chan string), make(chan string)
}
-- consecutive_params.go --
package undeclared

func consecutiveParams() {
	var s string
	undefinedConsecutiveParams(s, s) //@diag("undefinedConsecutiveParams", re"(undeclared name|undefined): undefinedConsecutiveParams")
}
-- error_param.go --
package undeclared

func errorParam() {
	var err error
	undefinedErrorParam(err) //@diag("undefinedErrorParam", re"(undeclared name|undefined): undefinedErrorParam")
}
-- literals.go --
package undeclared

type T struct{}

func literals() {
	undefinedLiterals("hey compiler", T{}, &T{}) //@diag("undefinedLiterals", re"(undeclared name|undefined): undefinedLiterals")
}
-- operation.go --
package undeclared

import "time"

func operation() {
	undefinedOperation(10 * time.Second) //@diag("undefinedOperation", re"(undeclared name|undefined): undefinedOperation")
}
-- selector.go --
package undeclared

func selector() {
	m := map[int]bool{}
	undefinedSelector(m[1]) //@diag("undefinedSelector", re"(undeclared name|undefined): undefinedSelector")
}
-- slice.go --
package undeclared

func slice() {
	undefinedSlice([]int{1, 2}) //@diag("undefinedSlice", re"(undeclared name|undefined): undefinedSlice")
}
-- tuple.go --
package undeclared

func tuple() {
	undefinedTuple(b()) //@diag("undefinedTuple", re"(undeclared name|undefined): undefinedTuple")
}

func b() (string, error) {
	return "", nil
}
-- unique.go --
package undeclared

func uniqueArguments() {
	var s string
	var i int
	undefinedUniqueArguments(s, i, s) //@diag("undefinedUniqueArguments", re"(undeclared name|undefined): undefinedUniqueArguments")
}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/undeclared/missingfunction.txt
================================================
This test checks the quick fix for undefined functions.

-- channels.go --
package missingfunction

func channels(s string) {
	undefinedChannels(c()) //@quickfix("undefinedChannels", re"(undeclared|undefined)", channels)
}

func c() (<-chan string, chan string) {
	return make(<-chan string), make(chan string)
}
-- @channels/channels.go --
@@ -7 +7,4 @@
+func undefinedChannels(ch1 <-chan string, ch2 chan string) {
+	panic("unimplemented")
+}
+
-- consecutive.go --
package missingfunction

func consecutiveParams() {
	var s string
	undefinedConsecutiveParams(s, s) //@quickfix("undefinedConsecutiveParams", re"(undeclared|undefined)", consecutive)
}
-- @consecutive/consecutive.go --
@@ -7 +7,4 @@
+
+func undefinedConsecutiveParams(s1, s2 string) {
+	panic("unimplemented")
+}
-- error.go --
package missingfunction

func errorParam() {
	var err error
	undefinedErrorParam(err) //@quickfix("undefinedErrorParam", re"(undeclared|undefined)", error)
}
-- @error/error.go --
@@ -7 +7,4 @@
+
+func undefinedErrorParam(err error) {
+	panic("unimplemented")
+}
-- literals.go --
package missingfunction

type T struct{}

func literals() {
	undefinedLiterals("hey compiler", T{}, &T{}) //@quickfix("undefinedLiterals", re"(undeclared|undefined)", literals)
}
-- @literals/literals.go --
@@ -8 +8,4 @@
+
+func undefinedLiterals(s string, t1 T, t2 *T) {
+	panic("unimplemented")
+}
-- operation.go --
package missingfunction

import "time"

func operation() {
	undefinedOperation(10 * time.Second) //@quickfix("undefinedOperation", re"(undeclared|undefined)", operation)
}
-- @operation/operation.go --
@@ -8 +8,4 @@
+
+func undefinedOperation(duration time.Duration) {
+	panic("unimplemented")
+}
-- selector.go --
package missingfunction

func selector() {
	m := map[int]bool{}
	undefinedSelector(m[1]) //@quickfix("undefinedSelector", re"(undeclared|undefined)", selector)
}
-- @selector/selector.go --
@@ -7 +7,4 @@
+
+func undefinedSelector(b bool) {
+	panic("unimplemented")
+}
-- slice.go --
package missingfunction

func slice() {
	undefinedSlice([]int{1, 2}) //@quickfix("undefinedSlice", re"(undeclared|undefined)", slice)
}
-- @slice/slice.go --
@@ -6 +6,4 @@
+
+func undefinedSlice(i []int) {
+	panic("unimplemented")
+}
-- tuple.go --
package missingfunction

func tuple() {
	undefinedTuple(b()) //@quickfix("undefinedTuple", re"(undeclared|undefined)", tuple)
}

func b() (string, error) {
	return "", nil
}
-- @tuple/tuple.go --
@@ -7 +7,4 @@
+func undefinedTuple(s string, err error) {
+	panic("unimplemented")
+}
+
-- unique_params.go --
package missingfunction

func uniqueArguments() {
	var s string
	var i int
	undefinedUniqueArguments(s, i, s) //@quickfix("undefinedUniqueArguments", re"(undeclared|undefined)", unique)
}
-- @unique/unique_params.go --
@@ -8 +8,4 @@
+
+func undefinedUniqueArguments(s1 string, i int, s2 string) {
+	panic("unimplemented")
+}
-- param.go --
package missingfunction

func inferFromParam() {
	f(as_param()) //@quickfix("as_param", re"undefined", infer_param)
}

func f(i int) {}
-- @infer_param/param.go --
@@ -7 +7,4 @@
+func as_param() int {
+	panic("unimplemented")
+}
+
-- assign.go --
package missingfunction

func inferFromAssign() {
	i := 42
	i = i
	i = assign() //@quickfix("assign", re"undefined", infer_assign)
}
-- @infer_assign/assign.go --
@@ -8 +8,4 @@
+
+func assign() int {
+	panic("unimplemented")
+}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/undeclared/undeclared_variable.txt
================================================
Tests of suggested fixes for "undeclared name" diagnostics,
which are of ("compiler", "error") type.

-- flags --
-ignore_extra_diags

-- go.mod --
module example.com
go 1.12

-- a.go --
package undeclared_var

func a() {
	z, _ := 1+y, 11 //@quickfix("y", re"(undeclared name|undefined): y", a)
	_ = z
}

-- @a/a.go --
@@ -4 +4 @@
+	y := 0
-- b.go --
package undeclared_var

func b() {
	if 100 < 90 {
	} else if 100 > n+2 { //@quickfix("n", re"(undeclared name|undefined): n", b)
	}
}

-- @b/b.go --
@@ -4 +4 @@
+	n := 0
-- c.go --
package undeclared_var

func c() {
	for i < 200 { //@quickfix("i", re"(undeclared name|undefined): i", c)
	}
	r() //@diag("r", re"(undeclared name|undefined): r")
}

-- @c/c.go --
@@ -4 +4 @@
+	i := 0
-- add_colon.go --
package undeclared_var

func addColon() {
	ac = 1 //@quickfix("ac", re"(undeclared name|undefined): ac", add_colon)
}

-- @add_colon/add_colon.go --
@@ -4 +4 @@
-	ac = 1 //@quickfix("ac", re"(undeclared name|undefined): ac", add_colon)
+	ac := 1 //@quickfix("ac", re"(undeclared name|undefined): ac", add_colon)
-- add_colon_first.go --
package undeclared_var

func addColonAtFirstStmt() {
	ac = 1
	ac = 2
	ac = 3
	b := ac //@quickfix("ac", re"(undeclared name|undefined): ac", add_colon_first)
}

-- @add_colon_first/add_colon_first.go --
@@ -4 +4 @@
-	ac = 1
+	ac := 1
-- self_assign.go --
package undeclared_var

func selfAssign() {
	ac = ac + 1
	ac = ac + 2 //@quickfix("ac", re"(undeclared name|undefined): ac", lhs)
	ac = ac + 3 //@quickfix("ac + 3", re"(undeclared name|undefined): ac", rhs)
}

-- @lhs/self_assign.go --
@@ -4 +4 @@
+	ac := nil
-- @rhs/self_assign.go --
@@ -4 +4 @@
+	ac := 0
-- correct_type.go --
package undeclared_var
import "fmt"
func selfAssign() {
	fmt.Printf(ac) //@quickfix("ac", re"(undeclared name|undefined): ac", string)
}
-- @string/correct_type.go --
@@ -4 +4 @@
+	ac := ""
-- ignore.go --
package undeclared_var
import "fmt"
type Foo struct {
	bar int
}
func selfAssign() {
	f := Foo{}
	b = f.bar
	c := bar //@quickfix("bar", re"(undeclared name|undefined): bar", ignore)
}
-- @ignore/ignore.go --
@@ -9 +9 @@
+	bar := nil


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/undeclared/undeclaredfunc.txt
================================================
This test checks the quick fix for "undeclared: f" that declares the
missing function. See #47558.

-- a.go --
package a

func _() int { return f(1, "") } //@quickfix(re"f.1", re"unde(fined|clared name): f", x)

-- @x/a.go --
@@ -3 +3 @@
-func _() int { return f(1, "") } //@quickfix(re"f.1", re"unde(fined|clared name): f", x)
+func _() int { return f(1, "") }
@@ -5 +5,4 @@
+func f(i int, s string) int {
+	panic("unimplemented")
+} //@quickfix(re"f.1", re"unde(fined|clared name): f", x)
+


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/unusedrequire.txt
================================================
This test checks the suggested fix to remove unused require statements from
go.mod files.

-- flags --
-write_sumfile=a

-- proxy/example.com@v1.0.0/x.go --
package pkg
const X = 1

-- a/go.mod --
module mod.com

go 1.14

require example.com v1.0.0 //@quickfix("require", re"not used", a)

-- @a/a/go.mod --
@@ -4,3 +4 @@
-
-require example.com v1.0.0 //@quickfix("require", re"not used", a)
-
-- a/main.go --
package main
func main() {}


================================================
FILE: gopls/internal/test/marker/testdata/quickfix/unusedrequire_gowork.txt
================================================
This test checks the suggested fix to remove unused require statements from
go.mod files, when a go.work file is used.

Note that unlike unusedrequire.txt, we need not write go.sum files when
a go.work file is used.

-- proxy/example.com@v1.0.0/x.go --
package pkg
const X = 1

-- go.work --
go 1.21

use (
	./a
	./b
)
-- a/go.mod --
module mod.com/a

go 1.14

require example.com v1.0.0 //@quickfix("require", re"not used", a)

-- @a/a/go.mod --
@@ -4,3 +4 @@
-
-require example.com v1.0.0 //@quickfix("require", re"not used", a)
-
-- a/main.go --
package main
func main() {}

-- b/go.mod --
module mod.com/b

go 1.14

require example.com v1.0.0 //@quickfix("require", re"not used", b)

-- @b/b/go.mod --
@@ -4,3 +4 @@
-
-require example.com v1.0.0 //@quickfix("require", re"not used", b)
-
-- b/main.go --
package main
func main() {}


================================================
FILE: gopls/internal/test/marker/testdata/references/crosspackage.txt
================================================
Test of basic cross-package references.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type X struct {
	Y int //@loc(typeXY, "Y")
}

-- b/b.go --
package b

import "example.com/a"

func GetXes() []a.X {
	return []a.X{
		{
			Y: 1, //@loc(GetXesY, "Y"), refs("Y", typeXY, GetXesY, anotherXY)
		},
	}
}

-- c/c.go --
package c

import "example.com/b"

func _() {
        xes := b.GetXes()
        for _, x := range xes { //@loc(defX, "x")
                _ = x.Y //@loc(useX, "x"), loc(anotherXY, "Y"), loc(beforeX, re"()x"), loc(afterX, re"()x"), loc(beforeY, re"()Y"), loc(afterY, re"Y()")
				//@refs(beforeY, typeXY, anotherXY, GetXesY)
				//@refs(afterY, typeXY, anotherXY, GetXesY)
				//@refs(anotherXY, typeXY, anotherXY, GetXesY)

				//@refs(beforeX, defX, useX)
				//@refs(afterX, defX, useX)
				//@refs(useX, defX, useX)
        }
}


================================================
FILE: gopls/internal/test/marker/testdata/references/imports.txt
================================================
Test of references to local package names (imports).

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

import "os" //@loc(osDef, `"os"`), refs("os", osDef, osUse)

import fmt2 "fmt" //@loc(fmt2Def, `fmt2`), refs("fmt2", fmt2Def, fmt2Use)

func _() {
	os.Getwd() //@loc(osUse, "os")
	fmt2.Println() //@loc(fmt2Use, "fmt2")
}


================================================
FILE: gopls/internal/test/marker/testdata/references/interfaces.txt
================================================
Test of references applied to concrete and interface types that are
related by assignability. The result includes references to both.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type first interface {
	common() //@loc(firCommon, "common"), refs("common", firCommon, xCommon, zCommon)
	firstMethod() //@loc(firMethod, "firstMethod"), refs("firstMethod", firMethod, xfMethod, zfMethod)
}

type second interface {
	common() //@loc(secCommon, "common"), refs("common", secCommon, yCommon, zCommon)
	secondMethod() //@loc(secMethod, "secondMethod"), refs("secondMethod", secMethod, ysMethod, zsMethod)
}

type s struct {}

func (*s) common() {} //@loc(sCommon, "common"), refs("common", sCommon, xCommon, yCommon, zCommon)

func (*s) firstMethod() {} //@loc(sfMethod, "firstMethod"), refs("firstMethod", sfMethod, xfMethod, zfMethod)

func (*s) secondMethod() {} //@loc(ssMethod, "secondMethod"), refs("secondMethod", ssMethod, ysMethod, zsMethod)

func main() {
	var x first = &s{}
	var y second = &s{}

	x.common() //@loc(xCommon, "common"), refs("common", firCommon, xCommon, zCommon)
	x.firstMethod() //@loc(xfMethod, "firstMethod"), refs("firstMethod", firMethod, xfMethod, zfMethod)
	y.common() //@loc(yCommon, "common"), refs("common", secCommon, yCommon, zCommon)
	y.secondMethod() //@loc(ysMethod, "secondMethod"), refs("secondMethod", secMethod, ysMethod, zsMethod)

	var z *s = &s{}
	z.firstMethod() //@loc(zfMethod, "firstMethod"), refs("firstMethod", sfMethod, xfMethod, zfMethod)
	z.secondMethod() //@loc(zsMethod, "secondMethod"), refs("secondMethod", ssMethod, ysMethod, zsMethod)
	z.common() //@loc(zCommon, "common"), refs("common", sCommon, xCommon, yCommon, zCommon)
}


================================================
FILE: gopls/internal/test/marker/testdata/references/intrapackage.txt
================================================
Basic test of references within a single package.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type i int //@loc(decli, "i"), refs("i", decli, argi, returni, embeddedi)

func _(_ i) []bool { //@loc(argi, "i")
	return nil
}

func _(_ []byte) i { //@loc(returni, "i")
	return 0
}

var q string //@loc(declq, "q"), refs("q", declq, assignq, bobq)

var Q string //@loc(declQ, "Q"), refs("Q", declQ)

func _() {
	q = "hello" //@loc(assignq, "q")
	bob := func(_ string) {}
	bob(q) //@loc(bobq, "q")
}

type e struct {
	i //@loc(embeddedi, "i"), refs("i", embeddedi, embeddediref)
}

func _() {
	_ = e{}.i //@loc(embeddediref, "i")
}


================================================
FILE: gopls/internal/test/marker/testdata/references/issue58506.txt
================================================
Regression test for 'references' bug golang/go#58506.

The 'references' query below, applied to method A.F, implicitly uses
the 'implementation' operation. The correct response includes two
references to B.F, one from package b and one from package d.
However, the incremental 'implementation' algorithm had a bug that
cause it to fail to report the reference from package b.

The reason was that the incremental implementation uses different
algorithms for the local and global cases (with disjoint results), and
that when it discovered that type A satisfies interface B and thus
that B.F must be included among the global search targets, the
implementation forgot to also search package b for local references
to B.F.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

type A int

func (A) F() {} //@loc(refa, "F"), refs("F", refa, refb, refd)

-- b/b.go --
package b

import (
	"example.com/a"
	"example.com/c"
)

type B interface{ F() }

var _ B = a.A(0)
var _ B = c.C(0)

var _ = B.F //@loc(refb, "F")

-- c/c.go --
package c

type C int

// Even though C.F is "rename coupled" to A.F by B.F,
// it should not be among the results.
func (C) F() {}

-- d/d.go --
package d

import "example.com/b"

var _ any = b.B.F //@loc(refd, "F")


================================================
FILE: gopls/internal/test/marker/testdata/references/issue59851.txt
================================================
Regression test for 'references' bug golang/go#59851.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type Iface interface {
     Method()
}

type implOne struct{}

func (implOne) Method() {} //@loc(def1, "Method"), refs(def1, def1, ref1, iref, ireftest)

var _ = implOne.Method //@loc(ref1, "Method")
var _ = Iface(nil).Method //@loc(iref, "Method")

-- a/a_test.go --
package a

type implTwo struct{}

func (implTwo) Method() {} //@loc(def2, "Method"), refs(def2, def2, iref, ref2, ireftest)

var _ = implTwo.Method //@loc(ref2, "Method")
var _ = Iface(nil).Method //@loc(ireftest, "Method")


================================================
FILE: gopls/internal/test/marker/testdata/references/issue60369.txt
================================================
Regression test for 'references' bug golang/go#60369: a references
query on the embedded type name T in struct{p.T} instead reports all
references to the package name p.

The bug was fixed in release go1.21 of go/types.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type A struct{}
const C = 0

-- b/b.go --
package b

import a "example.com/a" //@loc(adef, "a")
type s struct {
	a.A //@loc(Aref1, "A"), loc(aref1, "a"), refs(Aref1, Aref1, Aref3), refs(aref1, adef, aref1, aref2, aref3)
}
var _ a.A //@loc(aref2, re" (a)"), loc(Aref2, "A")
var _ = s{}.A //@loc(Aref3, "A")
const _ = a.C //@loc(aref3, "a")


================================================
FILE: gopls/internal/test/marker/testdata/references/issue60622.txt
================================================
Regression test for 'references' bug golang/go#60622:
references to methods of generics were missing.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

type G[T any] struct{}

func (G[T]) M() {} //@loc(Mdef, "M"), refs(Mdef, Mdef, Mref)

-- b/b.go --
package b

import "example.com/a"

func _() {
	new(a.G[int]).M() //@loc(Mref, "M")
}


================================================
FILE: gopls/internal/test/marker/testdata/references/issue60676.txt
================================================
This test verifies that even after importing from export data, the references
algorithm is able to find all references to struct fields or methods that are
shared by types from multiple packages. See golang/go#60676.

Note that the marker test runner awaits the initial workspace load, so export
data should be populated at the time references are requested.

-- go.mod --
module mod.test

go 1.18

-- a/a.go --
package a

type A struct {
	F int //@loc(FDef, "F")
	E //@loc(EDef, "E")
}

type E struct {
	G string //@loc(GDef, "G")
}

type AI interface {
	M() //@loc(MDef, "M")
	EI
	error
}

type EI interface {
	N() //@loc(NDef, "N")
}

type T[P any] struct{ f P }

type Error error


-- b/b.go --
package b

import "mod.test/a"

type B a.A

type BI a.AI

type T a.T[int] // must not panic

-- c/c.go --
package c

import "mod.test/b"

func _() {
	x := b.B{
		F: 42, //@refs("F", FDef, "F", Fuse)
	}
	x.G = "hi" //@refs("G", GDef, "G")
	_ = x.E //@refs("E", EDef, "E")
	_ = x.F //@loc(Fuse, "F")
}

func _(y b.BI) {
	_ = y.M //@refs("M", MDef, "M")
	_ = y.N //@refs("N", NDef, "N")
}


================================================
FILE: gopls/internal/test/marker/testdata/references/issue61618.txt
================================================
Regression test for 'references' bug golang/go#61618:
references to instantiated fields were missing.

-- go.mod --
module example.com
go 1.18

-- a.go --
package a

// This file is adapted from the example in the issue.

type builder[S ~[]F, F ~string] struct {
	name string
	elements S //@loc(def, "elements"), refs(def, def, assign, use)
	elemData map[F][]ElemData[F]
}

type ElemData[F ~string] struct {
  Name F
}

type BuilderImpl[S ~[]F, F ~string] struct{ builder[S, F] }

func NewBuilderImpl[S ~[]F, F ~string](name string)  *BuilderImpl[S, F] {
  impl := &BuilderImpl[S,F]{
	builder[S, F]{
	  name: name,
	  elements: S{}, //@loc(assign, "elements"), refs(assign, def, assign, use)
	  elemData: map[F][]ElemData[F]{},
	},
  }

  _ = impl.elements //@loc(use, "elements"), refs(use, def, assign, use)
  return impl
}


================================================
FILE: gopls/internal/test/marker/testdata/references/issue67978.txt
================================================

This test exercises a references query on an exported method that
conflicts with a field name. This ill-typed input violates the
assumption that if type T has a method, then the method set of T is
nonempty, which led to a crash.

See https://github.com/golang/go/issues/67978.

-- a.go --
package p

type E struct { X int } //@ diag(re"()X", re"field.*same name")

func (E) X() {} //@ loc(a, "X"), refs("X", a, b), diag(re"()X", re"method.*same name")

var _ = new(E).X //@ loc(b, "X")




================================================
FILE: gopls/internal/test/marker/testdata/references/issue75810.txt
================================================
-- go.work --
go 1.22

use ./a
use ./b
use ./c

-- a/go.mod --
module example.com/a

go 1.22

require example.com/b v0.0.1 //@ refs("/b", bmod, a_b, a2_b, a3_b)

-- a/a.go --
package a

import "example.com/b" //@ loc(a_b, `"example.com/b"`)

var _ = b.B

-- a/a2.go --
package a

import "example.com/b" //@ loc(a2_b, `"example.com/b"`)

var _ = b.B

-- a/a3/a3.go --
package a

import "example.com/b" //@ loc(a3_b, `"example.com/b"`)

var _ = b.B

-- b/go.mod --
module example.com/b //@ loc(bmod, re"^.*?b")

go 1.22

-- b/b.go --
package b

var B int

-- c/go.mod --
module example.com/c

go 1.22

require example.com/a v0.0.1
require example.com/b v0.0.1 //@ refs("/b",bmod, c_b)
-- c/c.go --
package c

import "example.com/b" //@ loc(c_b, `"example.com/b"`)

var _ = b.B


================================================
FILE: gopls/internal/test/marker/testdata/references/issue75810A.txt
================================================
Find references to example.com/b, but not to example.com/b/x
-- go.work --
go 1.22

use ./a
use ./b
use ./b/x
use ./c

-- a/go.mod --
module example.com/a

go 1.22

require example.com/b v0.0.1 //@ refs("/b", bmod, a_b, a2_b, a3_b)
-- a/a.go --
package a

import "example.com/b" //@ loc(a_b, `"example.com/b"`)
import "example.com/b/x" //@ loc(a4_x, `"example.com/b/x"`)

var _ = b.B
var _ = x.X

-- a/a2.go --
package a

import "example.com/b" //@ loc(a2_b, `"example.com/b"`)

var _ = b.B

-- a/a3/a3.go --
package a

import "example.com/b" //@ loc(a3_b, `"example.com/b"`)
import "example.com/b/x" //@ loc(a3_x, `"example.com/b/x"`)


var _ = b.B
var _ = x.X

-- b/go.mod --
module example.com/b //@ loc(bmod, re"^.*?b")

go 1.22

-- b/b.go --
package b

var B int

-- b/x/go.mod --
module example.com/b/x

go 1.22

-- b/x/x.go --
package x

var X int
-- c/go.mod --
module example.com/c

go 1.22

require example.com/a v0.0.1
require example.com/b v0.0.1 //@ refs("/b", bmod, c_b)
-- c/c.go --
package c

import "example.com/b" //@ loc(c_b, `"example.com/b"`)

var _ = b.B



================================================
FILE: gopls/internal/test/marker/testdata/references/issue76872.txt
================================================
This test exercises a references query at a position where an empty selection
might be considered enclosed both by the node before (Ident) and the node after
(FuncType). It ensures that we find the reference of the syntax node before the
cursor.

See https://github.com/golang/go/issues/76872.

-- main.go --
package main

// re"foo()" matches the zero-width position after "foo", not the call parens.
func foo() {} //@ loc(decl, "foo"), refs(re"foo()", decl, call)

func _() {
	foo() //@ loc(call, "foo")
}


================================================
FILE: gopls/internal/test/marker/testdata/references/shadow.txt
================================================
Test of references in the presence of shadowing.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

func _() {
	x := 123 //@loc(x1, "x"), refs("x", x1, x1ref)
	_ = x //@loc(x1ref, "x")
	{
		x := "hi" //@loc(x2, "x"), refs("x", x2, x2ref)
		_ = x //@loc(x2ref, "x")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/references/test.txt
================================================
Test of references between the extra files of a test variant
and the regular package.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

func fn() {} //@loc(def, "fn"), refs("fn", def, use)

type t struct { g int } //@loc(gdef, "g")
type u struct { t }

var _ = new(u).g //@loc(gref, "g"), refs("g", gdef, gref)
// TODO(adonovan): fix: gref2 and gdef2 are missing.

-- a/a_test.go --
package a

func _() {
	fn() //@loc(use, "fn")

	_ = new(u).g //@loc(gref2, "g"), refs("g", gdef2, gref, gref2)
}

// This declaration changes the meaning of u.t in the test.
func (u) g() {} //@loc(gdef2, "g")


================================================
FILE: gopls/internal/test/marker/testdata/references/typeswitch.txt
================================================
Tests of reference to implicit type switch vars, which are
a special case in go/types.Info{Def,Use,Implicits}.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

func _(x any) {
	switch y := x.(type) { //@loc(yDecl, "y"), refs("y", yDecl, yInt, yDefault)
	case int:
		println(y) //@loc(yInt, "y"), refs("y", yDecl, yInt, yDefault)
	default:
		println(y) //@loc(yDefault, "y")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/rename/bad.txt
================================================
This test checks that rename fails in the presence of errors.

-- go.mod --
module golang.org/lsptests/bad

go 1.18

-- bad.go --
package bad

type myStruct struct {
}

func (s *myStruct) sFunc() bool { //@renameerr("sFunc", "rFunc", "not possible because \"bad.go\" in \"golang.org/lsptests/bad\" has errors")
	return s.Bad //@diag("Bad", re"no field or method")
}

-- bad_test.go --
package bad


-- badsyntax/badsyntax.go --
package badsyntax

type S struct {}

func (s *S) sFunc() bool { //@renameerr("sFunc", "rFunc", "not possible because \"badsyntax.go\" in \"golang.org/lsptests/bad/badsyntax\" has errors")
	# //@diag("#", re"expected statement, found")
}


================================================
FILE: gopls/internal/test/marker/testdata/rename/basic.txt
================================================
This test performs basic coverage of 'rename' within a single package.

-- basic.go --
package p

func _(x int) { println(x) } //@rename("x", "y", xToy)

-- @xToy/basic.go --
@@ -3 +3 @@
-func _(x int) { println(x) } //@rename("x", "y", xToy)
+func _(y int) { println(y) } //@rename("x", "y", xToy)
-- alias.go --
package p

// from golang/go#61625
type LongNameHere struct{}
type A = LongNameHere //@rename("A", "B", AToB)
func Foo() A

-- errors.go --
package p

func _(x []int) { //@renameerr("_", "blank", `can't rename "_"`)
	x = append(x, 1) //@renameerr("append", "blank", "built in and cannot be renamed")
	x = nil //@renameerr("nil", "blank", "built in and cannot be renamed")
	x = nil //@renameerr("x", "x", "old and new names are the same: x")
	_ = 1 //@renameerr("1", "x", "no identifier found")
}

-- @AToB/alias.go --
@@ -5,2 +5,2 @@
-type A = LongNameHere //@rename("A", "B", AToB)
-func Foo() A
+type B = LongNameHere //@rename("A", "B", AToB)
+func Foo() B


================================================
FILE: gopls/internal/test/marker/testdata/rename/conflict.txt
================================================
This test exercises some renaming conflict scenarios
and ensures that the errors are informative.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- go.mod --
module example.com
go 1.12

-- super/p.go --
package super

var x int

func _(y int) {
	println(x)
	println(y) //@renameerr("y", "x", errSuperBlockConflict)
}

-- @errSuperBlockConflict --
super/p.go:5:8: renaming this var "y" to "x"
super/p.go:6:10:	would shadow this reference
super/p.go:3:5:	to the var declared here
-- sub/p.go --
package sub

var a int

func _(b int) {
	println(a) //@renameerr("a", "b", errSubBlockConflict)
	println(b)
}

-- @errSubBlockConflict --
sub/p.go:3:5: renaming this var "a" to "b"
sub/p.go:6:10:	would cause this reference to become shadowed
sub/p.go:5:8:	by this intervening var definition
-- pkgname/p.go --
package pkgname

import e1 "errors" //@renameerr("e1", "errors", errImportConflict)
import "errors"

var _ = errors.New
var _ = e1.New

-- @errImportConflict --
pkgname/p.go:3:8: renaming this imported package name "e1" to "errors"
pkgname/p.go:4:8:	conflicts with imported package name in same block
-- pkgname2/p1.go --
package pkgname2
var x int

-- pkgname2/p2.go --
package pkgname2
import "errors" //@renameerr("errors", "x", errImportConflict2)
var _ = errors.New

-- @errImportConflict2 --
pkgname2/p2.go:2:8: renaming this imported package name "errors" to "x" would conflict
pkgname2/p1.go:2:5:	with this package member var


================================================
FILE: gopls/internal/test/marker/testdata/rename/crosspkg.txt
================================================
This test checks cross-package renaming.

-- go.mod --
module golang.org/lsptests/rename

go 1.18

-- crosspkg/crosspkg.go --
package crosspkg

func Foo() { //@rename("Foo", "Dolphin", FooToDolphin)

}

var Bar int //@rename("Bar", "Tomato", BarToTomato)

-- crosspkg/another/another.go --
package another

type (
	I interface{ F() }
	C struct{ I }
)

func (C) g()

func _() {
	var x I = C{}
	x.F() //@rename("F", "G", FToG)
}

var _ = C.g

-- crosspkg/other/other.go --
package other

import "golang.org/lsptests/rename/crosspkg"

func Other() {
	crosspkg.Bar //@diag("crosspkg", re"not used")
	crosspkg.Foo() //@rename("Foo", "Flamingo", FooToFlamingo)
}

-- @BarToTomato/crosspkg/crosspkg.go --
@@ -7 +7 @@
-var Bar int //@rename("Bar", "Tomato", BarToTomato)
+var Tomato int //@rename("Bar", "Tomato", BarToTomato)
-- @BarToTomato/crosspkg/other/other.go --
@@ -6 +6 @@
-	crosspkg.Bar //@diag("crosspkg", re"not used")
+	crosspkg.Tomato //@diag("crosspkg", re"not used")
-- @FToG/crosspkg/another/another.go --
@@ -4 +4 @@
-	I interface{ F() }
+	I interface{ G() }
@@ -12 +12 @@
-	x.F() //@rename("F", "G", FToG)
+	x.G() //@rename("F", "G", FToG)
-- @FooToDolphin/crosspkg/crosspkg.go --
@@ -3 +3 @@
-func Foo() { //@rename("Foo", "Dolphin", FooToDolphin)
+func Dolphin() { //@rename("Foo", "Dolphin", FooToDolphin)
-- @FooToDolphin/crosspkg/other/other.go --
@@ -7 +7 @@
-	crosspkg.Foo() //@rename("Foo", "Flamingo", FooToFlamingo)
+	crosspkg.Dolphin() //@rename("Foo", "Flamingo", FooToFlamingo)
-- @FooToFlamingo/crosspkg/crosspkg.go --
@@ -3 +3 @@
-func Foo() { //@rename("Foo", "Dolphin", FooToDolphin)
+func Flamingo() { //@rename("Foo", "Dolphin", FooToDolphin)
-- @FooToFlamingo/crosspkg/other/other.go --
@@ -7 +7 @@
-	crosspkg.Foo() //@rename("Foo", "Flamingo", FooToFlamingo)
+	crosspkg.Flamingo() //@rename("Foo", "Flamingo", FooToFlamingo)


================================================
FILE: gopls/internal/test/marker/testdata/rename/doclink.txt
================================================
This test checks that doc links are also handled correctly (golang/go#64495).

-- go.mod --
module example.com

go 1.21

-- a/a.go --
package a

// Foo just for test [Foo]
// reference others objects [A] [B] [C] [C.F] [C.PF]
func Foo() {} //@rename("Foo", "Bar", FooToBar)

const A = 1 //@rename("A", "AA", AToAA)

var B = 1 //@rename("B", "BB", BToBB)

type C int //@rename("C", "CC", CToCC)

func (C) F() {} //@rename("F", "FF", FToFF)

func (*C) PF() {} //@rename("PF", "PFF", PFToPFF)

// D just for test [*D]
type D int //@rename("D", "DD", DToDD)

// E test generic type doc link [E] [E.Foo]
type E[T any] struct { //@rename("E", "EE", EToEE)
	Field T
}

func (E[T]) Foo() {} //@rename("Foo", "Bar", EFooToEBar)

-- b/b.go --
package b

import aa "example.com/a" //@rename("aa", "a", pkgRename)

// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
// reference pointer type [*aa.D]
// reference generic type links [aa.E] [aa.E.Foo]
func FooBar() {
	aa.Foo()
	var e aa.E[int]
	e.Foo()
}


-- @FooToBar/a/a.go --
@@ -3 +3 @@
-// Foo just for test [Foo]
+// Bar just for test [Bar]
@@ -5 +5 @@
-func Foo() {} //@rename("Foo", "Bar", FooToBar)
+func Bar() {} //@rename("Foo", "Bar", FooToBar)
-- @FooToBar/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Bar] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
@@ -9 +9 @@
-	aa.Foo()
+	aa.Bar()
-- @AToAA/a/a.go --
@@ -4 +4 @@
-// reference others objects [A] [B] [C] [C.F] [C.PF]
+// reference others objects [AA] [B] [C] [C.F] [C.PF]
@@ -7 +7 @@
-const A = 1 //@rename("A", "AA", AToAA)
+const AA = 1 //@rename("A", "AA", AToAA)
-- @AToAA/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Foo] [aa.AA] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
-- @BToBB/a/a.go --
@@ -4 +4 @@
-// reference others objects [A] [B] [C] [C.F] [C.PF]
+// reference others objects [A] [BB] [C] [C.F] [C.PF]
@@ -9 +9 @@
-var B = 1 //@rename("B", "BB", BToBB)
+var BB = 1 //@rename("B", "BB", BToBB)
-- @BToBB/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Foo] [aa.A] [aa.BB] [aa.C] [aa.C.F] [aa.C.PF]
-- @CToCC/a/a.go --
@@ -4 +4 @@
-// reference others objects [A] [B] [C] [C.F] [C.PF]
+// reference others objects [A] [B] [CC] [CC.F] [CC.PF]
@@ -11 +11 @@
-type C int //@rename("C", "CC", CToCC)
+type CC int //@rename("C", "CC", CToCC)
@@ -13 +13 @@
-func (C) F() {} //@rename("F", "FF", FToFF)
+func (CC) F() {} //@rename("F", "FF", FToFF)
@@ -15 +15 @@
-func (*C) PF() {} //@rename("PF", "PFF", PFToPFF)
+func (*CC) PF() {} //@rename("PF", "PFF", PFToPFF)
-- @CToCC/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.CC] [aa.CC.F] [aa.CC.PF]
-- @FToFF/a/a.go --
@@ -4 +4 @@
-// reference others objects [A] [B] [C] [C.F] [C.PF]
+// reference others objects [A] [B] [C] [C.FF] [C.PF]
@@ -13 +13 @@
-func (C) F() {} //@rename("F", "FF", FToFF)
+func (C) FF() {} //@rename("F", "FF", FToFF)
-- @FToFF/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.FF] [aa.C.PF]
-- @PFToPFF/a/a.go --
@@ -4 +4 @@
-// reference others objects [A] [B] [C] [C.F] [C.PF]
+// reference others objects [A] [B] [C] [C.F] [C.PFF]
@@ -15 +15 @@
-func (*C) PF() {} //@rename("PF", "PFF", PFToPFF)
+func (*C) PFF() {} //@rename("PF", "PFF", PFToPFF)
-- @PFToPFF/b/b.go --
@@ -5 +5 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
+// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PFF]
-- @pkgRename/b/b.go --
@@ -3 +3 @@
-import aa "example.com/a" //@rename("aa", "a", pkgRename)
+import "example.com/a" //@rename("aa", "a", pkgRename)
@@ -5,3 +5,3 @@
-// FooBar just for test [aa.Foo] [aa.A] [aa.B] [aa.C] [aa.C.F] [aa.C.PF]
-// reference pointer type [*aa.D]
-// reference generic type links [aa.E] [aa.E.Foo]
+// FooBar just for test [a.Foo] [a.A] [a.B] [a.C] [a.C.F] [a.C.PF]
+// reference pointer type [*a.D]
+// reference generic type links [a.E] [a.E.Foo]
@@ -9,2 +9,2 @@
-	aa.Foo()
-	var e aa.E[int]
+	a.Foo()
+	var e a.E[int]
-- @DToDD/a/a.go --
@@ -17,2 +17,2 @@
-// D just for test [*D]
-type D int //@rename("D", "DD", DToDD)
+// DD just for test [*DD]
+type DD int //@rename("D", "DD", DToDD)
-- @DToDD/b/b.go --
@@ -6 +6 @@
-// reference pointer type [*aa.D]
+// reference pointer type [*aa.DD]
-- @EToEE/a/a.go --
@@ -20,2 +20,2 @@
-// E test generic type doc link [E] [E.Foo]
-type E[T any] struct { //@rename("E", "EE", EToEE)
+// EE test generic type doc link [EE] [EE.Foo]
+type EE[T any] struct { //@rename("E", "EE", EToEE)
@@ -25 +25 @@
-func (E[T]) Foo() {} //@rename("Foo", "Bar", EFooToEBar)
+func (EE[T]) Foo() {} //@rename("Foo", "Bar", EFooToEBar)
-- @EToEE/b/b.go --
@@ -7 +7 @@
-// reference generic type links [aa.E] [aa.E.Foo]
+// reference generic type links [aa.EE] [aa.EE.Foo]
@@ -10 +10 @@
-	var e aa.E[int]
+	var e aa.EE[int]
-- @EFooToEBar/a/a.go --
@@ -20 +20 @@
-// E test generic type doc link [E] [E.Foo]
+// E test generic type doc link [E] [E.Bar]
@@ -25 +25 @@
-func (E[T]) Foo() {} //@rename("Foo", "Bar", EFooToEBar)
+func (E[T]) Bar() {} //@rename("Foo", "Bar", EFooToEBar)
-- @EFooToEBar/b/b.go --
@@ -7 +7 @@
-// reference generic type links [aa.E] [aa.E.Foo]
+// reference generic type links [aa.E] [aa.E.Bar]
@@ -11 +11 @@
-	e.Foo()
+	e.Bar()


================================================
FILE: gopls/internal/test/marker/testdata/rename/embed.txt
================================================
This test exercises renaming of types used as embedded fields.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type A int //@rename("A", "A2", type)

-- b/b.go --
package b

import "example.com/a"

type B struct { a.A } //@rename("A", "A3", embedA)

var _ = new(B).A //@renameerr("A", "A4", errAnonField)

type C int

type D struct {
    C //@rename("C", "C2", embedC)
}

-- @errAnonField --
an embedded field must be renamed at its declaration (since it renames the type too)
-- @type/a/a.go --
@@ -3 +3 @@
-type A int //@rename("A", "A2", type)
+type A2 int //@rename("A", "A2", type)
-- @type/b/b.go --
@@ -5 +5 @@
-type B struct { a.A } //@rename("A", "A3", embedA)
+type B struct { a.A2 } //@rename("A", "A3", embedA)
@@ -7 +7 @@
-var _ = new(B).A //@renameerr("A", "A4", errAnonField)
+var _ = new(B).A2 //@renameerr("A", "A4", errAnonField)
-- @embedA/a/a.go --
@@ -3 +3 @@
-type A int //@rename("A", "A2", type)
+type A3 int //@rename("A", "A2", type)
-- @embedA/b/b.go --
@@ -5 +5 @@
-type B struct { a.A } //@rename("A", "A3", embedA)
+type B struct { a.A3 } //@rename("A", "A3", embedA)
@@ -7 +7 @@
-var _ = new(B).A //@renameerr("A", "A4", errAnonField)
+var _ = new(B).A3 //@renameerr("A", "A4", errAnonField)
-- @embedC/b/b.go --
@@ -9 +9 @@
-type C int
+type C2 int
@@ -12 +12 @@
-    C //@rename("C", "C2", embedC)
+    C2 //@rename("C", "C2", embedC)


================================================
FILE: gopls/internal/test/marker/testdata/rename/func.txt
================================================
This test checks basic functionality for renaming (=changing) a function
signature.

-- go.mod --
module example.com

go 1.20

-- a/a.go --
package a

//@rename(Foo, "func(i int, s string)", unchanged)
//@rename(Foo, "func(s string, i int)", reverse)
//@rename(Foo, "func(s string)", dropi)
//@rename(Foo, "func(i int)", drops)
//@rename(Foo, "func()", dropboth)
//@renameerr(Foo, "func(i int, s string, t bool)", "not yet supported")
//@renameerr(Foo, "func(i string)", "not yet supported")
//@renameerr(Foo, "func(i int, s string) int", "not yet supported")

func Foo(i int, s string) { //@loc(Foo, "func")
}

func _() {
	Foo(0, "hi")
}
-- @dropboth/a/a.go --
@@ -12 +12 @@
-func Foo(i int, s string) { //@loc(Foo, "func")
+func Foo() { //@loc(Foo, "func")
@@ -16 +16 @@
-	Foo(0, "hi")
+	Foo()
-- @dropi/a/a.go --
@@ -12 +12 @@
-func Foo(i int, s string) { //@loc(Foo, "func")
+func Foo(s string) { //@loc(Foo, "func")
@@ -16 +16 @@
-	Foo(0, "hi")
+	Foo("hi")
-- @drops/a/a.go --
@@ -12 +12 @@
-func Foo(i int, s string) { //@loc(Foo, "func")
+func Foo(i int) { //@loc(Foo, "func")
@@ -16 +16 @@
-	Foo(0, "hi")
+	Foo(0)
-- @reverse/a/a.go --
@@ -12 +12 @@
-func Foo(i int, s string) { //@loc(Foo, "func")
+func Foo(s string, i int) { //@loc(Foo, "func")
@@ -16 +16 @@
-	Foo(0, "hi")
+	Foo("hi", 0)
-- @unchanged/a/a.go --


================================================
FILE: gopls/internal/test/marker/testdata/rename/generics.txt
================================================
This test exercises various renaming features on generic code.

Fixed bugs:

- golang/go#61614: renaming a method of a type in a package that uses type
  parameter composite lits used to panic, because previous iterations of the
  satisfy analysis did not account for this language feature.

- golang/go#61635: renaming type parameters did not work when they were
  capitalized and the package was imported by another package.

-- go.mod --
module example.com
go 1.20

-- a.go --
package a

type I int

func (I) m() {} //@rename("m", "M", mToM)

func _[P ~[]int]() {
	_ = P{}
}

var _ = I.m

-- @mToM/a.go --
@@ -5 +5 @@
-func (I) m() {} //@rename("m", "M", mToM)
+func (I) M() {} //@rename("m", "M", mToM)
@@ -11 +11 @@
-var _ = I.m
+var _ = I.M
-- g.go --
package a

type S[P any] struct { //@rename("P", "Q", PToQ)
	P P
	F func(P) P
}

func F[R any](r R) {
	var _ R //@rename("R", "S", RToS)
}

-- @PToQ/g.go --
@@ -3,3 +3,3 @@
-type S[P any] struct { //@rename("P", "Q", PToQ)
-	P P
-	F func(P) P
+type S[Q any] struct { //@rename("P", "Q", PToQ)
+	P Q
+	F func(Q) Q
-- @RToS/g.go --
@@ -8,2 +8,2 @@
-func F[R any](r R) {
-	var _ R //@rename("R", "S", RToS)
+func F[S any](r S) {
+	var _ S //@rename("R", "S", RToS)
-- issue61635/p.go --
package issue61635

type builder[S ~[]F, F ~string] struct { //@rename("S", "T", SToT)
	name string
	elements S
	elemData map[F][]ElemData[F]
	// other fields...
}

type ElemData[F ~string] struct {
  Name F
  // other fields...
}

type BuilderImpl[S ~[]F, F ~string] struct{ builder[S, F] }

-- importer/i.go --
package importer

import "example.com/issue61635" // importing is necessary to repro golang/go#61635

var _ issue61635.ElemData[string]

-- @SToT/issue61635/p.go --
@@ -3 +3 @@
-type builder[S ~[]F, F ~string] struct { //@rename("S", "T", SToT)
+type builder[T ~[]F, F ~string] struct { //@rename("S", "T", SToT)
@@ -5 +5 @@
-	elements S
+	elements T
-- instances/type.go --
package instances

type R[P any] struct { //@rename("R", "u", Rtou)
	Next *R[P] //@rename("R", "s", RTos)
}

func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
	var x R[P]
	return rv.Do(x) //@rename("Do", "Do2", DoToDo2)
}

func _() {
	var x R[int] //@rename("R", "r", RTor)
	x = x.Do(x)
}

-- @RTos/instances/type.go --
@@ -3,2 +3,2 @@
-type R[P any] struct { //@rename("R", "u", Rtou)
-	Next *R[P] //@rename("R", "s", RTos)
+type s[P any] struct { //@rename("R", "u", Rtou)
+	Next *s[P] //@rename("R", "s", RTos)
@@ -7,2 +7,2 @@
-func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
-	var x R[P]
+func (rv s[P]) Do(s[P]) s[P] { //@rename("Do", "Do1", DoToDo1)
+	var x s[P]
@@ -13 +13 @@
-	var x R[int] //@rename("R", "r", RTor)
+	var x s[int] //@rename("R", "r", RTor)
-- @Rtou/instances/type.go --
@@ -3,2 +3,2 @@
-type R[P any] struct { //@rename("R", "u", Rtou)
-	Next *R[P] //@rename("R", "s", RTos)
+type u[P any] struct { //@rename("R", "u", Rtou)
+	Next *u[P] //@rename("R", "s", RTos)
@@ -7,2 +7,2 @@
-func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
-	var x R[P]
+func (rv u[P]) Do(u[P]) u[P] { //@rename("Do", "Do1", DoToDo1)
+	var x u[P]
@@ -13 +13 @@
-	var x R[int] //@rename("R", "r", RTor)
+	var x u[int] //@rename("R", "r", RTor)
-- @DoToDo1/instances/type.go --
@@ -7 +7 @@
-func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
+func (rv R[P]) Do1(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
@@ -9 +9 @@
-	return rv.Do(x) //@rename("Do", "Do2", DoToDo2)
+	return rv.Do1(x) //@rename("Do", "Do2", DoToDo2)
@@ -14 +14 @@
-	x = x.Do(x)
+	x = x.Do1(x)
-- @DoToDo2/instances/type.go --
@@ -7 +7 @@
-func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
+func (rv R[P]) Do2(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
@@ -9 +9 @@
-	return rv.Do(x) //@rename("Do", "Do2", DoToDo2)
+	return rv.Do2(x) //@rename("Do", "Do2", DoToDo2)
@@ -14 +14 @@
-	x = x.Do(x)
+	x = x.Do2(x)
-- instances/func.go --
package instances

func Foo[P any](p P) { //@rename("Foo", "Bar", FooToBar)
	Foo(p) //@rename("Foo", "Baz", FooToBaz)
}

-- @FooToBar/instances/func.go --
@@ -3,2 +3,2 @@
-func Foo[P any](p P) { //@rename("Foo", "Bar", FooToBar)
-	Foo(p) //@rename("Foo", "Baz", FooToBaz)
+func Bar[P any](p P) { //@rename("Foo", "Bar", FooToBar)
+	Bar(p) //@rename("Foo", "Baz", FooToBaz)
-- @FooToBaz/instances/func.go --
@@ -3,2 +3,2 @@
-func Foo[P any](p P) { //@rename("Foo", "Bar", FooToBar)
-	Foo(p) //@rename("Foo", "Baz", FooToBaz)
+func Baz[P any](p P) { //@rename("Foo", "Bar", FooToBar)
+	Baz(p) //@rename("Foo", "Baz", FooToBaz)
-- @RTor/instances/type.go --
@@ -3,2 +3,2 @@
-type R[P any] struct { //@rename("R", "u", Rtou)
-	Next *R[P] //@rename("R", "s", RTos)
+type r[P any] struct { //@rename("R", "u", Rtou)
+	Next *r[P] //@rename("R", "s", RTos)
@@ -7,2 +7,2 @@
-func (rv R[P]) Do(R[P]) R[P] { //@rename("Do", "Do1", DoToDo1)
-	var x R[P]
+func (rv r[P]) Do(r[P]) r[P] { //@rename("Do", "Do1", DoToDo1)
+	var x r[P]
@@ -13 +13 @@
-	var x R[int] //@rename("R", "r", RTor)
+	var x r[int] //@rename("R", "r", RTor)


================================================
FILE: gopls/internal/test/marker/testdata/rename/generics_basic.txt
================================================
This test exercise basic renaming of generic code.

-- embedded.go --
package a

type foo[P any] int //@rename("foo", "bar", fooTobar)

var x struct{ foo[int] }

var _ = x.foo

-- @fooTobar/embedded.go --
@@ -3 +3 @@
-type foo[P any] int //@rename("foo", "bar", fooTobar)
+type bar[P any] int //@rename("foo", "bar", fooTobar)
@@ -5 +5 @@
-var x struct{ foo[int] }
+var x struct{ bar[int] }
@@ -7 +7 @@
-var _ = x.foo
+var _ = x.bar
-- generics.go --
package a

type G[P any] struct {
	F int
}

func (G[_]) M() {}

func F[P any](P) {
	var p P //@rename("P", "Q", PToQ)
	_ = p
}

func _() {
	var x G[int] //@rename("G", "H", GToH)
	_ = x.F      //@rename("F", "K", FToK)
	x.M()        //@rename("M", "N", MToN)

	var y G[string]
	_ = y.F
	y.M()
}

-- @FToK/generics.go --
@@ -4 +4 @@
-	F int
+	K int
@@ -16 +16 @@
-	_ = x.F      //@rename("F", "K", FToK)
+	_ = x.K      //@rename("F", "K", FToK)
@@ -20 +20 @@
-	_ = y.F
+	_ = y.K
-- @GToH/generics.go --
@@ -3 +3 @@
-type G[P any] struct {
+type H[P any] struct {
@@ -7 +7 @@
-func (G[_]) M() {}
+func (H[_]) M() {}
@@ -15 +15 @@
-	var x G[int] //@rename("G", "H", GToH)
+	var x H[int] //@rename("G", "H", GToH)
@@ -19 +19 @@
-	var y G[string]
+	var y H[string]
-- @MToN/generics.go --
@@ -7 +7 @@
-func (G[_]) M() {}
+func (G[_]) N() {}
@@ -17 +17 @@
-	x.M()        //@rename("M", "N", MToN)
+	x.N()        //@rename("M", "N", MToN)
@@ -21 +21 @@
-	y.M()
+	y.N()
-- @PToQ/generics.go --
@@ -9,2 +9,2 @@
-func F[P any](P) {
-	var p P //@rename("P", "Q", PToQ)
+func F[Q any](Q) {
+	var p Q //@rename("P", "Q", PToQ)
-- unions.go --
package a

type T string //@rename("T", "R", TToR)

type C interface {
	T | ~int //@rename("T", "S", TToS)
}

-- @TToR/unions.go --
@@ -3 +3 @@
-type T string //@rename("T", "R", TToR)
+type R string //@rename("T", "R", TToR)
@@ -6 +6 @@
-	T | ~int //@rename("T", "S", TToS)
+	R | ~int //@rename("T", "S", TToS)
-- @TToS/unions.go --
@@ -3 +3 @@
-type T string //@rename("T", "R", TToR)
+type S string //@rename("T", "R", TToR)
@@ -6 +6 @@
-	T | ~int //@rename("T", "S", TToS)
+	S | ~int //@rename("T", "S", TToS)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue39614.txt
================================================

-- flags --
-ignore_extra_diags

-- p.go --
package issue39614

func fn() {
	var foo bool //@rename("foo", "bar", fooTobar)
	make(map[string]bool
	if true {
	}
}

-- @fooTobar/p.go --
@@ -4 +4 @@
-	var foo bool //@rename("foo", "bar", fooTobar)
+	var bar bool //@rename("foo", "bar", fooTobar)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue42134.txt
================================================
Regression test for #42134,
"rename fails to update doc comment for local variable of function type"

-- 1.go --
package issue42134

func _() {
	// foo computes things.
	foo := func() {}

	foo() //@rename("foo", "bar", fooTobar)
}
-- @fooTobar/1.go --
@@ -4,2 +4,2 @@
-	// foo computes things.
-	foo := func() {}
+	// bar computes things.
+	bar := func() {}
@@ -7 +7 @@
-	foo() //@rename("foo", "bar", fooTobar)
+	bar() //@rename("foo", "bar", fooTobar)
-- 2.go --
package issue42134

import "fmt"

func _() {
	// minNumber is a min number.
	// Second line.
	minNumber := min(1, 2)
	fmt.Println(minNumber) //@rename("minNumber", "res", minNumberTores)
}

func min(a, b int) int { return a + b }
-- @minNumberTores/2.go --
@@ -6 +6 @@
-	// minNumber is a min number.
+	// res is a min number.
@@ -8,2 +8,2 @@
-	minNumber := min(1, 2)
-	fmt.Println(minNumber) //@rename("minNumber", "res", minNumberTores)
+	res := min(1, 2)
+	fmt.Println(res) //@rename("minNumber", "res", minNumberTores)
-- 3.go --
package issue42134

func _() {
	/*
	tests contains test cases
	*/
	tests := []struct { //@rename("tests", "testCases", testsTotestCases)
		in, out string
	}{}
	_ = tests
}
-- @testsTotestCases/3.go --
@@ -5 +5 @@
-	tests contains test cases
+	testCases contains test cases
@@ -7 +7 @@
-	tests := []struct { //@rename("tests", "testCases", testsTotestCases)
+	testCases := []struct { //@rename("tests", "testCases", testsTotestCases)
@@ -10 +10 @@
-	_ = tests
+	_ = testCases
-- 4.go --
package issue42134

func _() {
	// a is equal to 5. Comment must stay the same

	a := 5
	_ = a //@rename("a", "b", aTob)
}
-- @aTob/4.go --
@@ -6,2 +6,2 @@
-	a := 5
-	_ = a //@rename("a", "b", aTob)
+	b := 5
+	_ = b //@rename("a", "b", aTob)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue42301.txt
================================================
This test verifies the fix for golang/go#42301: renaming an ident inside its doc
comment should also rename the ident.

-- go.mod --
module example.com

go 1.21
-- a/a.go --
package a

// Foo doesn't do anything, Foo is just an empty function. //@rename(re"()Foo", "Bar", fooToBar), renameerr(re"()anything", "Bar", "no identifier found")
func Foo() {}

func _() {
	Foo()
}

-- b/b.go --
package b

import "example.com/a"

func _() {
	a.Foo()
}

-- c/c.go --
package c

// A is an empty struct. //@rename(re"()A", "B", aToB)
type A struct {}

-- d/d.go --
package d

// Bar doesn't do anything, Bar is just an empty function. //@rename(re", ()Bar", "Foo", barToFoo)
func Bar() {}

-- @aToB/c/c.go --
@@ -3,2 +3,2 @@
-// A is an empty struct. //@rename(re"()A", "B", aToB)
-type A struct {}
+// B is an empty struct. //@rename(re"()B", "B", aToB)
+type B struct {}
-- @barToFoo/d/d.go --
@@ -3,2 +3,2 @@
-// Bar doesn't do anything, Bar is just an empty function. //@rename(re", ()Bar", "Foo", barToFoo)
-func Bar() {}
+// Foo doesn't do anything, Foo is just an empty function. //@rename(re", ()Foo", "Foo", barToFoo)
+func Foo() {}
-- @fooToBar/a/a.go --
@@ -3,2 +3,2 @@
-// Foo doesn't do anything, Foo is just an empty function. //@rename(re"()Foo", "Bar", fooToBar), renameerr(re"()anything", "Bar", "no identifier found")
-func Foo() {}
+// Bar doesn't do anything, Bar is just an empty function. //@rename(re"()Bar", "Bar", fooToBar), renameerr(re"()anything", "Bar", "no identifier found")
+func Bar() {}
@@ -7 +7 @@
-	Foo()
+	Bar()
-- @fooToBar/b/b.go --
@@ -6 +6 @@
-	a.Foo()
+	a.Bar()


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue43616.txt
================================================
This test verifies the fix for golang/go#43616: renaming mishandles embedded
fields.

-- p.go --
package issue43616

type foo int //@rename("foo", "bar", fooToBar),preparerename("oo","foo",span="foo")

var x struct{ foo } //@rename("foo", "baz", fooToBaz)

var _ = x.foo //@renameerr("foo", "quux", "must be renamed at its declaration")
-- @fooToBar/p.go --
@@ -3 +3 @@
-type foo int //@rename("foo", "bar", fooToBar),preparerename("oo","foo",span="foo")
+type bar int //@rename("foo", "bar", fooToBar),preparerename("oo","foo",span="foo")
@@ -5 +5 @@
-var x struct{ foo } //@rename("foo", "baz", fooToBaz)
+var x struct{ bar } //@rename("foo", "baz", fooToBaz)
@@ -7 +7 @@
-var _ = x.foo //@renameerr("foo", "quux", "must be renamed at its declaration")
+var _ = x.bar //@renameerr("foo", "quux", "must be renamed at its declaration")
-- @fooToBaz/p.go --
@@ -3 +3 @@
-type foo int //@rename("foo", "bar", fooToBar),preparerename("oo","foo",span="foo")
+type baz int //@rename("foo", "bar", fooToBar),preparerename("oo","foo",span="foo")
@@ -5 +5 @@
-var x struct{ foo } //@rename("foo", "baz", fooToBaz)
+var x struct{ baz } //@rename("foo", "baz", fooToBaz)
@@ -7 +7 @@
-var _ = x.foo //@renameerr("foo", "quux", "must be renamed at its declaration")
+var _ = x.baz //@renameerr("foo", "quux", "must be renamed at its declaration")


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue57479.txt
================================================
Test renaming a parameter to the name of an imported package
referenced by one of the function parameters.

See golang/go#57479

-- go.mod --
module golang.org/lsptests/rename

go 1.18
-- a/a.go --
package a

import (
    "fmt"
    "math"
)

func _(x fmt.Stringer) {} //@rename("x", "fmt", xToFmt)

func _(x int, y fmt.Stringer) {} //@rename("x", "fmt", xyToFmt)

func _(x [math.MaxInt]bool) {} //@rename("x", "math", xToMath)
-- @xToFmt/a/a.go --
@@ -8 +8 @@
-func _(x fmt.Stringer) {} //@rename("x", "fmt", xToFmt)
+func _(fmt fmt.Stringer) {} //@rename("x", "fmt", xToFmt)
-- @xToMath/a/a.go --
@@ -12 +12 @@
-func _(x [math.MaxInt]bool) {} //@rename("x", "math", xToMath)
+func _(math [math.MaxInt]bool) {} //@rename("x", "math", xToMath)
-- @xyToFmt/a/a.go --
@@ -10 +10 @@
-func _(x int, y fmt.Stringer) {} //@rename("x", "fmt", xyToFmt)
+func _(fmt int, y fmt.Stringer) {} //@rename("x", "fmt", xyToFmt)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue60752.txt
================================================

This test renames a receiver, type parameter, parameter or result var
whose name matches a package-level decl. Prior to go1.22, this used to
cause a spurious shadowing error because of an edge case in the
behavior of types.Scope for function parameters and results.

This is a regression test for issue #60752, a bug in the type checker.

-- go.mod --
module example.com
go 1.18

-- a/type.go --
package a

type t int

-- a/recv.go --
package a

func (v t) _() {} //@ rename("v", "t", recv)

-- a/param.go --
package a

func _(v t) {} //@ rename("v", "t", param)

-- a/result.go --
package a

func _() (v t) { return } //@ rename("v", "t", result)

-- a/typeparam.go --
package a

func _[v t]() {} //@ renameerr("v", "t", re"would shadow (.|\n)*type.go:3:6")

-- b/b.go --
package b

import _ "example.com/a"

-- @param/a/param.go --
@@ -3 +3 @@
-func _(v t) {} //@ rename("v", "t", param)
+func _(t t) {} //@ rename("v", "t", param)
-- @recv/a/recv.go --
@@ -3 +3 @@
-func (v t) _() {} //@ rename("v", "t", recv)
+func (t t) _() {} //@ rename("v", "t", recv)
-- @result/a/result.go --
@@ -3 +3 @@
-func _() (v t) { return } //@ rename("v", "t", result)
+func _() (t t) { return } //@ rename("v", "t", result)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue60789.txt
================================================

This test renames an exported method of an unexported type,
which is an edge case for objectpath, since it computes a path
from a syntax package that is no good when applied to an
export data package.

See issue #60789.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type unexported int
func (unexported) F() {} //@rename("F", "G", fToG)

var _ = unexported(0).F

-- b/b.go --
package b

// The existence of this package is sufficient to exercise
// the bug even though it cannot reference a.unexported.

import _ "example.com/a"

-- @fToG/a/a.go --
@@ -4 +4 @@
-func (unexported) F() {} //@rename("F", "G", fToG)
+func (unexported) G() {} //@rename("F", "G", fToG)
@@ -6 +6 @@
-var _ = unexported(0).F
+var _ = unexported(0).G


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue61294.txt
================================================

This test renames a parameter var whose name is the same as a
package-level var, which revealed a bug in isLocal.

This is a regression test for issue #61294.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

func One()

func Two(One int) //@rename("One", "Three", OneToThree)

-- b/b.go --
package b

import _ "example.com/a"

-- @OneToThree/a/a.go --
@@ -5 +5 @@
-func Two(One int) //@rename("One", "Three", OneToThree)
+func Two(Three int) //@rename("One", "Three", OneToThree)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue61640.txt
================================================
This test verifies that gopls can rename instantiated fields.

-- a.go --
package a

// This file is adapted from the example in the issue.

type builder[S ~[]int] struct {
	elements S //@rename("elements", "elements2", OneToTwo)
}

type BuilderImpl[S ~[]int] struct{ builder[S] }

func NewBuilderImpl[S ~[]int](name string)  *BuilderImpl[S] {
  impl := &BuilderImpl[S]{
	builder[S]{
	  elements: S{},
	},
  }

  _ = impl.elements
  return impl
}
-- @OneToTwo/a.go --
@@ -6 +6 @@
-	elements S //@rename("elements", "elements2", OneToTwo)
+	elements2 S //@rename("elements", "elements2", OneToTwo)
@@ -14 +14 @@
-	  elements: S{},
+	  elements2: S{},
@@ -18 +18 @@
-  _ = impl.elements
+  _ = impl.elements2


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue61813.txt
================================================
This test exercises the panic reported in golang/go#61813.

-- p.go --
package p

type P struct{}

func (P) M() {} //@rename("M", "N", MToN)

var _ = []*P{{}}
-- @MToN/p.go --
@@ -5 +5 @@
-func (P) M() {} //@rename("M", "N", MToN)
+func (P) N() {} //@rename("M", "N", MToN)


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue65098.txt
================================================
This is a test for issue 65098: a renaming in package a does not
propagate to package b, even though the two packages are coupled via
an assignment in c, which is renamed.

     c
    / \
   a   b

The bug (a dup of #58461) is not yet fixed, so the golden file records
the wrong behavior (i.e. no changes to package b).
TODO(adonovan): fix.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type I interface {
	F() //@ rename("F", "FF", fToFF)
}

-- b/b.go --
package b

type S struct{}

func (s S) F() {}

-- c/c.go --
package c

import (
	"example.com/a"
	"example.com/b"
)

var _ a.I = b.S{}
var _ = a.I.F

-- @fToFF/a/a.go --
@@ -4 +4 @@
-	F() //@ rename("F", "FF", fToFF)
+	FF() //@ rename("F", "FF", fToFF)
-- @fToFF/c/c.go --
@@ -9 +9 @@
-var _ = a.I.F
+var _ = a.I.FF


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue67069.txt
================================================
This test verifies spurious pkgname conflicts.
Issue golang/go#67069.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- go.mod --
module example
go 1.19

-- aa/a.go --
package aa

var cc int //@rename("cc", "aa", CToA)
const C = 0
const D = 0

-- aa/a_test.go --
package aa_test

import "example/aa"

var _ = aa.C //@rename("aa", "bb", AToB)
-- @CToA/aa/a.go --
@@ -3 +3 @@
-var cc int //@rename("cc", "aa", CToA)
+var aa int //@rename("cc", "aa", CToA)
-- @AToB/aa/a_test.go --
@@ -3 +3 @@
-import "example/aa"
+import bb "example/aa"
@@ -5 +5 @@
-var _ = aa.C //@rename("aa", "bb", AToB)
+var _ = bb.C //@rename("aa", "bb", AToB)
-- bb/b.go --
package bb

import "example/aa"

var _ = aa.C
var bb int //@renameerr("bb", "aa", errImportConflict)

-- @errImportConflict --
bb/b.go:6:5: renaming this var "bb" to "aa" would conflict
bb/b.go:3:8:	with this imported package name
-- aa/a_internal_test.go --
package aa

var _ = D //@rename("D", "aa", DToA)
-- @DToA/aa/a_internal_test.go --
@@ -3 +3 @@
-var _ = D //@rename("D", "aa", DToA)
+var _ = aa //@rename("D", "aa", DToA)
-- @DToA/aa/a.go --
@@ -5 +5 @@
-const D = 0
+const aa = 0


================================================
FILE: gopls/internal/test/marker/testdata/rename/issue70968.txt
================================================
Test that an (ill-typed) redeclaration of a name, which causes
types.Info.Defs to lack an entry, doesn't lead to gopls to crash in
renaming. Now, it proceeds with a partial rename.

See golang/go#70968

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

type T int               //@ diag("T", re"T redeclared")
type T struct { f int }  //@ diag("T", re"T redeclared"), rename("f", "g", out)

-- @out/a/a.go --
@@ -4 +4 @@
-type T struct { f int }  //@ diag("T", re"T redeclared"), rename("f", "g", out)
+type T struct { g int }  //@ diag("T", re"T redeclared"), rename("f", "g", out)


================================================
FILE: gopls/internal/test/marker/testdata/rename/methods.txt
================================================
This test exercises renaming of interface methods.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

type A int

func (A) F() {} //@renameerr("F", "G", errAfToG)

-- b/b.go --
package b

import "example.com/a"
import "example.com/c"

type B interface { F() } //@rename("F", "G", BfToG)

var _ B = a.A(0)
var _ B = c.C(0)

var _ = B.F

-- c/c.go --
package c

type C int

func (C) F() {} //@renameerr("F", "G", errCfToG)

-- d/d.go --
package d

import "example.com/b"

var _ = b.B.F

-- @errAfToG --
a/a.go:5:10: renaming this method "F" to "G"
b/b.go:6:6:	would make example.com/a.A no longer assignable to interface B
b/b.go:6:20:	(rename example.com/b.B.F if you intend to change both types)
-- @BfToG/b/b.go --
@@ -6 +6 @@
-type B interface { F() } //@rename("F", "G", BfToG)
+type B interface { G() } //@rename("F", "G", BfToG)
@@ -11 +11 @@
-var _ = B.F
+var _ = B.G
-- @BfToG/d/d.go --
@@ -5 +5 @@
-var _ = b.B.F
+var _ = b.B.G
-- @errCfToG --
c/c.go:5:10: renaming this method "F" to "G"
b/b.go:6:6:	would make example.com/c.C no longer assignable to interface B
b/b.go:6:20:	(rename example.com/b.B.F if you intend to change both types)


================================================
FILE: gopls/internal/test/marker/testdata/rename/packagedecl.txt
================================================
This test verifies the behavior of renaming a package declaration when package move is enabled.
It tests the following:
- Invalid renames:
	- Moving across a module boundary
	- Moving to a package that already exists

- Renames edge cases:
	- Naming collisions
	- Renaming to internal package
		- Not allowed when there is some importer of the package to be moved
		that is not in the internal package
	- Impact of renaming on _test packages
	- Renaming with the exact same path - no edits produced

-- flags --
-ignore_extra_diags

-- go.work --
use .
use ./othermoddir

-- go.mod --
module golang.org/lsptests/rename

replace golang.org/lsptests/six/four => ./six/four

go 1.20
-- one/one.go --
package one //@ rename("one", "golang.org/lsptests/rename/one", sameName), rename("one", "golang.org/lsptests/rename/two", newNameSameDir), renameerr("one", "golang.org/lsptests/otherdir/one", re"cannot move package across module boundary")

-- three/three.go --
package three //@ renameerr("three", "golang.org/lsptests/othermod/three", re"cannot move package across module boundary"), renameerr("three", "golang.org/lsptests/rename/one", re"not empty")


-- six/six.go --
package six //@ renameerr("six", "golang.org/lsptests/rename/$$$", re"invalid package name")

import "golang.org/lsptests/rename/six/four"

func Foo() {
	four.Bar()
}

-- six/four/four.go --
package four //@ rename("four", "golang.org/lsptests/rename/five", moveUpOneDir), renameerr("four", "../relative", re"specifying relative paths in package rename not yet supported")

func Bar() {}

-- seven/seven/seven.go --
package seven

import
(
	"golang.org/lsptests/rename/six/four"
	five "golang.org/lsptests/rename/six"
)

func foo() {
	four.Bar()
}

-- importsnine/importsnine.go --
package importsnine //@ rename("importsnine", "golang.org/lsptests/rename/nine/internal/importsnine", allowedInternal) // only importers of this package are already in the internal package, so okay to move it

import (
	"golang.org/lsptests/rename/nine/nine/nine"
)

-- nine/nine/nine/nine.go --
package nine //@ renameerr("nine", "golang.org/lsptests/rename/nine/internal/nine", re"package move would result in illegal internal import")

-- nine/internal/helpers.go --
package internal

import "golang.org/lsptests/rename/importsnine"

-- seven/eight/eight.go --
package eight //@ rename("eight", "golang.org/lsptests/rename/six/eight", differentDir), rename("eight", "golang.org/lsptests/rename/nine/nine/nine/eight", moveDownTwoDirs)
-- fix/fix.go --
package fix //@ rename("fix", "golang.org/lsptests/rename/newFix", renameWithTestPkg)

import (
	"golang.org/lsptests/rename/seven/eight"
	)

-- seven/eight/other/other.go --
package other //@ rename("other", "golang.org/lsptests/rename/seven/eight/other/newDir1/newDir2", createNewDir)

-- seven/eight/other/newDir1/newDir2/newDir3/test.go --
package newDir3 // verifies that we can move the package above into a directory that already exists but is empty

-- fix/fix_test.go --
package fix_test
-- othermoddir/othermod/other.go --
package othermod

import "golang.org/lsptests/rename/nine/nine/nine"


-- othermoddir/go.mod --
module mod.com/other

-- foo/windows.go --
//go:build windows
package foo

-- foo/default.go --
//go:build !windows
package foo //@ renameerr("foo", "golang.org/lsptests/rename/foo2", re"ignored files")

-- bar/bar.go --
package foobar //@ renameerr("foobar", "golang.org/lsptests/rename/otherpath", re"does not match directory base name")

-- @moveDownTwoDirs/nine/nine/nine/eight/eight.go --
@@ -0,0 +1 @@
+package eight //@ rename("eight", "golang.org/lsptests/rename/six/eight", differentDir), rename("eight", "golang.org/lsptests/rename/nine/nine/nine/eight", moveDownTwoDirs)
-- @moveDownTwoDirs/seven/eight/eight.go --
@@ -1 +0,0 @@
-package eight //@ rename("eight", "golang.org/lsptests/rename/six/eight", differentDir), rename("eight", "golang.org/lsptests/rename/nine/nine/nine/eight", moveDownTwoDirs)
-- @moveUpOneDir/five/four.go --
@@ -0,0 +1,4 @@
+package five //@ rename("four", "golang.org/lsptests/rename/five", moveUpOneDir), renameerr("four", "../relative", re"specifying relative paths in package rename not yet supported")
+
+func Bar() {}
+
-- @moveUpOneDir/six/four/four.go --
@@ -1,4 +0,0 @@
-package four //@ rename("four", "golang.org/lsptests/rename/five", moveUpOneDir), renameerr("four", "../relative", re"specifying relative paths in package rename not yet supported")
-
-func Bar() {}
-
-- @moveUpOneDir/seven/seven/seven.go --
@@ -5 +5 @@
-	"golang.org/lsptests/rename/six/four"
+	five1 "golang.org/lsptests/rename/five"
@@ -10 +10 @@
-	four.Bar()
+	five1.Bar()
-- @newNameSameDir/one/one.go --
@@ -1,2 +0,0 @@
-package one //@ rename("one", "golang.org/lsptests/rename/one", sameName), rename("one", "golang.org/lsptests/rename/two", newNameSameDir), renameerr("one", "golang.org/lsptests/otherdir/one", re"cannot move package across module boundary")
-
-- @newNameSameDir/two/one.go --
@@ -0,0 +1,2 @@
+package two //@ rename("one", "golang.org/lsptests/rename/one", sameName), rename("one", "golang.org/lsptests/rename/two", newNameSameDir), renameerr("one", "golang.org/lsptests/otherdir/one", re"cannot move package across module boundary")
+
-- @sameName/one/one.go --
-- @moveUpOneDir/six/six.go --
@@ -3 +3 @@
-import "golang.org/lsptests/rename/six/four"
+import "golang.org/lsptests/rename/five"
@@ -6 +6 @@
-	four.Bar()
+	five.Bar()
-- @moveUpOneDir/go.mod --
@@ -3 +3 @@
-replace golang.org/lsptests/six/four => ./six/four
+replace golang.org/lsptests/six/four => ./five
-- @differentDir/seven/eight/eight.go --
@@ -1 +0,0 @@
-package eight //@ rename("eight", "golang.org/lsptests/rename/six/eight", differentDir), rename("eight", "golang.org/lsptests/rename/nine/nine/nine/eight", moveDownTwoDirs)
-- @differentDir/six/eight/eight.go --
@@ -0,0 +1 @@
+package eight //@ rename("eight", "golang.org/lsptests/rename/six/eight", differentDir), rename("eight", "golang.org/lsptests/rename/nine/nine/nine/eight", moveDownTwoDirs)
-- @differentDir/fix/fix.go --
@@ -4 +4 @@
-	"golang.org/lsptests/rename/seven/eight"
+	"golang.org/lsptests/rename/six/eight"
-- @moveDownTwoDirs/fix/fix.go --
@@ -4 +4 @@
-	"golang.org/lsptests/rename/seven/eight"
+	"golang.org/lsptests/rename/nine/nine/nine/eight"
-- @allowedInternal/importsnine/importsnine.go --
@@ -1,6 +0,0 @@
-package importsnine //@ rename("importsnine", "golang.org/lsptests/rename/nine/internal/importsnine", allowedInternal) // only importers of this package are already in the internal package, so okay to move it
-
-import (
-	"golang.org/lsptests/rename/nine/nine/nine"
-)
-
-- @allowedInternal/nine/internal/helpers.go --
@@ -3 +3 @@
-import "golang.org/lsptests/rename/importsnine"
+import "golang.org/lsptests/rename/nine/internal/importsnine"
-- @allowedInternal/nine/internal/importsnine/importsnine.go --
@@ -0,0 +1,6 @@
+package importsnine //@ rename("importsnine", "golang.org/lsptests/rename/nine/internal/importsnine", allowedInternal) // only importers of this package are already in the internal package, so okay to move it
+
+import (
+	"golang.org/lsptests/rename/nine/nine/nine"
+)
+
-- @renameWithTestPkg/fix/fix.go --
@@ -1,6 +0,0 @@
-package fix //@ rename("fix", "golang.org/lsptests/rename/newFix", renameWithTestPkg)
-
-import (
-	"golang.org/lsptests/rename/seven/eight"
-	)
-
-- @renameWithTestPkg/fix/fix_test.go --
@@ -1 +0,0 @@
-package fix_test
-- @renameWithTestPkg/newFix/fix.go --
@@ -0,0 +1,6 @@
+package newFix //@ rename("fix", "golang.org/lsptests/rename/newFix", renameWithTestPkg)
+
+import (
+	"golang.org/lsptests/rename/seven/eight"
+	)
+
-- @renameWithTestPkg/newFix/fix_test.go --
@@ -0,0 +1 @@
+package newFix_test
-- @createNewDir/seven/eight/other/other.go --
@@ -1,2 +0,0 @@
-package other //@ rename("other", "golang.org/lsptests/rename/seven/eight/other/newDir1/newDir2", createNewDir)
-
-- @createNewDir/seven/eight/other/newDir1/newDir2/other.go --
@@ -0,0 +1,2 @@
+package newDir2 //@ rename("other", "golang.org/lsptests/rename/seven/eight/other/newDir1/newDir2", createNewDir)
+


================================================
FILE: gopls/internal/test/marker/testdata/rename/pkgpath.txt
================================================
Test of PkgName renaming initiated over ImportSpec.Path.

-- go.mod --
module example.com

-- a/a.go --
package a

import "example.com/b" //@rename("b", "c", bToc)

var _ = b.B

-- a/a2.go --
package a

import b "example.com/b" //@rename(re"/(b)", "c", bToc2)

var _ = b.B

-- b/b.go --
package b

const B = 0

-- @bToc/a/a.go --
@@ -3 +3 @@
-import "example.com/b" //@rename("b", "c", bToc)
+import c "example.com/b" //@rename("b", "c", bToc)
@@ -5 +5 @@
-var _ = b.B
+var _ = c.B
-- @bToc2/a/a2.go --
@@ -3 +3 @@
-import b "example.com/b" //@rename(re"/(b)", "c", bToc2)
+import c "example.com/b" //@rename(re"/(b)", "c", bToc2)
@@ -5 +5 @@
-var _ = b.B
+var _ = c.B


================================================
FILE: gopls/internal/test/marker/testdata/rename/prepare.txt
================================================
This test verifies the behavior of textDocument/prepareRename.

-- settings.json --
{
	"deepCompletion": false
}

-- go.mod --
module golang.org/lsptests

go 1.18
-- types/types.go --
package types

type CoolAlias = int //@item(CoolAlias, "CoolAlias", "int", "type")

type X struct { //@item(X_struct, "X", "struct{...}", "struct")
	x int
}

type Y struct { //@item(Y_struct, "Y", "struct{...}", "struct")
	y int
}


type Bob interface { //@item(Bob_interface, "Bob", "interface{...}", "interface")
	Bobby()
}

func (*X) Bobby() {}
func (*Y) Bobby() {}

-- good/good0.go --
package good

var _ = stuff

func stuff() { //@item(good_stuff, "stuff", "func()", "func"),preparerename("stu", "stuff", span="stuff")
	x := 5
	random2(x) //@preparerename("dom", "random2", span="random2")
}

-- good/good1.go --
package good

import (
	"golang.org/lsptests/types" //@item(types_import, "types", "\"golang.org/lsptests/types\"", "package")
)

var _ = random

func random() int { //@item(good_random, "random", "func() int", "func")
	_ = "random() int" //@preparerename("random", "")
	y := 6 + 7         //@preparerename("7", "")
	return y           //@preparerename("return", "", span="")
}

func random2(y int) int { //@item(good_random2, "random2", "func(y int) int", "func"),item(good_y_param, "y", "int", "var")
	//@complete("", good_y_param, types_import, good_random, good_random2, good_stuff)
	var b types.Bob = &types.X{}   //@preparerename("ypes","types", span="types")
	if _, ok := b.(*types.X); ok { //@complete(re"()X", X_struct, Y_struct, Bob_interface, CoolAlias)
		_ = 0 // suppress "empty branch" diagnostic
	}

	return y
}


================================================
FILE: gopls/internal/test/marker/testdata/rename/prepare_func.txt
================================================
This test verifies the behavior of textDocument/prepareRename on function declarations.

-- settings.json --
{
	"deepCompletion": false
}

-- go.mod --
module golang.org/lsptests

go 1.18

-- main.go --
package main

func _(i int) //@ preparerename("unc", "func(i int)", span="func")

func _(i int) //@ preparerename("func", "func(i int)")

func _(a, b int) //@ preparerename("func", "func(a, b int)")

func _(a, _ int) //@ preparerename("func", "func(a, _0 int)")

func _(a, _, _ int) //@ preparerename("func", "func(a, _0, _1 int)")

func _(a, _, _, d int, _ string) //@ preparerename("func", "func(a, _0, _1, d int, _2 string)")

func _(a int, b string) //@ preparerename("func", "func(a int, b string)")

func _(a int, b ...string) //@ preparerename("func", "func(a int, b ...string)")

func _(a int, b string) error //@ preparerename("func", "func(a int, b string) error")

func _(a int, b string) (int, error) //@ preparerename("func", "func(a int, b string) (int, error)")

func _( //@ preparerename("func", "func(a int, b string)")
  a int,
	b string,
)

func _( //@ preparerename("func", "func(a int, b string) (int, error)")
  a int,
	b string,
) (int, error)


================================================
FILE: gopls/internal/test/marker/testdata/rename/prepare_move.txt
================================================
This test verifies the behavior of textDocument/prepareRename - we prompt with the full package path.

-- go.mod --
module golang.org/lsptests

go 1.20

-- b/b.go --
package b //@ preparerename("b", "golang.org/lsptests/b")

-- a/other.go --
// We prompt with the full package path, but changing a package directory is disabled when the package name does not match its directory base name. 
package other //@ preparerename("other", "golang.org/lsptests/a")


================================================
FILE: gopls/internal/test/marker/testdata/rename/random.txt
================================================
This test ports some "random" rename tests from the old marker tests.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests/rename

go 1.18
-- a/a.go --
package a

import (
	lg "log"
	"fmt" //@rename("fmt", "fmty", fmtTofmty)
	f2 "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
)

func Random() int {
	y := 6 + 7
	return y
}

func Random2(y int) int { //@rename("y", "z", yToz)
	return y
}

type Pos struct {
	x, y int
}

func (p *Pos) Sum() int {
	return p.x + p.y //@rename("x", "myX", xTomyX)
}

func _() {
	var p Pos   //@rename("p", "pos", pTopos)
	_ = p.Sum() //@rename("Sum", "GetSum", SumToGetSum)
}

func sw() {
	var x any

	switch y := x.(type) { //@rename("y", "y0", yToy0)
	case int:
		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
	case string:
		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
	default:
		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
	}
}
-- @SumToGetSum/a/a.go --
@@ -22 +22 @@
-func (p *Pos) Sum() int {
+func (p *Pos) GetSum() int {
@@ -28 +28 @@
-	_ = p.Sum() //@rename("Sum", "GetSum", SumToGetSum)
+	_ = p.GetSum() //@rename("Sum", "GetSum", SumToGetSum)
-- @f2Tof2name/a/a.go --
@@ -6 +6 @@
-	f2 "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
+	f2name "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2name.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @f2Tofmt2/a/a.go --
@@ -6 +6 @@
-	f2 "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
+	fmt2 "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		fmt2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @fmtTof2y/a/a.go --
@@ -6 +6 @@
-	f2 "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
+	f2y "fmt" //@rename("f2", "f2name", f2Tof2name),rename("fmt", "f2y", fmtTof2y)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2y.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @fmtTofmty/a/a.go --
@@ -5 +5 @@
-	"fmt" //@rename("fmt", "fmty", fmtTofmty)
+	fmty "fmt" //@rename("fmt", "fmty", fmtTofmty)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		fmty.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
-- @fmtToformat/a/a.go --
@@ -5 +5 @@
-	"fmt" //@rename("fmt", "fmty", fmtTofmty)
+	format "fmt" //@rename("fmt", "fmty", fmtTofmty)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		format.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
-- @lgTolog/a/a.go --
@@ -4 +4 @@
-	lg "log"
+	"log"
@@ -38 +38 @@
-		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
+		log.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
-- @pTopos/a/a.go --
@@ -27,2 +27,2 @@
-	var p Pos   //@rename("p", "pos", pTopos)
-	_ = p.Sum() //@rename("Sum", "GetSum", SumToGetSum)
+	var pos Pos   //@rename("p", "pos", pTopos)
+	_ = pos.Sum() //@rename("Sum", "GetSum", SumToGetSum)
-- @xTomyX/a/a.go --
@@ -19 +19 @@
-	x, y int
+	myX, y int
@@ -23 +23 @@
-	return p.x + p.y //@rename("x", "myX", xTomyX)
+	return p.myX + p.y //@rename("x", "myX", xTomyX)
-- @yToy0/a/a.go --
@@ -34 +34 @@
-	switch y := x.(type) { //@rename("y", "y0", yToy0)
+	switch y0 := x.(type) { //@rename("y", "y0", yToy0)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		fmt.Printf("%d", y0) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
@@ -38 +38 @@
-		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
+		lg.Printf("%s", y0) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2.Printf("%v", y0) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @yToy1/a/a.go --
@@ -34 +34 @@
-	switch y := x.(type) { //@rename("y", "y0", yToy0)
+	switch y1 := x.(type) { //@rename("y", "y0", yToy0)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		fmt.Printf("%d", y1) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
@@ -38 +38 @@
-		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
+		lg.Printf("%s", y1) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2.Printf("%v", y1) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @yToy2/a/a.go --
@@ -34 +34 @@
-	switch y := x.(type) { //@rename("y", "y0", yToy0)
+	switch y2 := x.(type) { //@rename("y", "y0", yToy0)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		fmt.Printf("%d", y2) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
@@ -38 +38 @@
-		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
+		lg.Printf("%s", y2) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2.Printf("%v", y2) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @yToy3/a/a.go --
@@ -34 +34 @@
-	switch y := x.(type) { //@rename("y", "y0", yToy0)
+	switch y3 := x.(type) { //@rename("y", "y0", yToy0)
@@ -36 +36 @@
-		fmt.Printf("%d", y) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
+		fmt.Printf("%d", y3) //@rename("y", "y1", yToy1),rename("fmt", "format", fmtToformat)
@@ -38 +38 @@
-		lg.Printf("%s", y) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
+		lg.Printf("%s", y3) //@rename("y", "y2", yToy2),rename("lg", "log", lgTolog)
@@ -40 +40 @@
-		f2.Printf("%v", y) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
+		f2.Printf("%v", y3) //@rename("y", "y3", yToy3),rename("f2", "fmt2", f2Tofmt2)
-- @yToz/a/a.go --
@@ -14,2 +14,2 @@
-func Random2(y int) int { //@rename("y", "z", yToz)
-	return y
+func Random2(z int) int { //@rename("y", "z", yToz)
+	return z
-- b/b.go --
package b

var c int //@renameerr("int", "uint", re"cannot be renamed")

func _() {
	a := 1 //@rename("a", "error", aToerror)
	a = 2
	_ = a
}

var (
	// Hello there.
	// Foo does the thing.
	Foo int //@rename("Foo", "Bob", FooToBob)
)

/*
Hello description
*/
func Hello() {} //@rename("Hello", "Goodbye", HelloToGoodbye)

-- c/c.go --
package c

import "golang.org/lsptests/rename/b"

func _() {
	b.Hello() //@rename("Hello", "Goodbye", HelloToGoodbye)
}

-- c/c2.go --
package c

//go:embed Static/*
var Static embed.FS //@rename("Static", "static", StaticTostatic)

-- @FooToBob/b/b.go --
@@ -13,2 +13,2 @@
-	// Foo does the thing.
-	Foo int //@rename("Foo", "Bob", FooToBob)
+	// Bob does the thing.
+	Bob int //@rename("Foo", "Bob", FooToBob)
-- @HelloToGoodbye/b/b.go --
@@ -18 +18 @@
-Hello description
+Goodbye description
@@ -20 +20 @@
-func Hello() {} //@rename("Hello", "Goodbye", HelloToGoodbye)
+func Goodbye() {} //@rename("Hello", "Goodbye", HelloToGoodbye)
-- @aToerror/b/b.go --
@@ -6,3 +6,3 @@
-	a := 1 //@rename("a", "error", aToerror)
-	a = 2
-	_ = a
+	error := 1 //@rename("a", "error", aToerror)
+	error = 2
+	_ = error
-- @HelloToGoodbye/c/c.go --
@@ -6 +6 @@
-	b.Hello() //@rename("Hello", "Goodbye", HelloToGoodbye)
+	b.Goodbye() //@rename("Hello", "Goodbye", HelloToGoodbye)
-- @StaticTostatic/c/c2.go --
@@ -4 +4 @@
-var Static embed.FS //@rename("Static", "static", StaticTostatic)
+var static embed.FS //@rename("Static", "static", StaticTostatic)


================================================
FILE: gopls/internal/test/marker/testdata/rename/recv.txt
================================================
This test exercises renaming of method receivers (golang/go#41892).

Notes:
- x to print fails for A.J because it would shadow the built-in print;
  that renaming is quietly skipped.
- various combinations of named, aliases, and pointers are tested.
- package b exercises generics.
- renaming a receiver declaration causes the broader renaming;
  renaming a receiver use (see vrefz) effects only a local renaming.

-- a/a.go --
package a

type T int
type A = T

func (T) F()   {}
func (t T) G() {} //@rename("t", "x", tx)
func (U T) H() {} //@rename("U", "v", Uv)
func (_ T) I() {}
func (v A) J() { print(-v) } //@rename(re"-(v)", "z", vrefz)
func (w *T) K() {}
func (x *A) L() {} //@rename("x", "print", xprint)

-- @tx/a/a.go --
@@ -7,2 +7,2 @@
-func (t T) G() {} //@rename("t", "x", tx)
-func (U T) H() {} //@rename("U", "v", Uv)
+func (x T) G() {} //@rename("t", "x", tx)
+func (x T) H() {} //@rename("U", "v", Uv)
@@ -10,2 +10,2 @@
-func (v A) J() { print(-v) } //@rename(re"-(v)", "z", vrefz)
-func (w *T) K() {}
+func (x A) J() { print(-x) } //@rename(re"-(v)", "z", vrefz)
+func (x *T) K() {}
-- @Uv/a/a.go --
@@ -7,2 +7,2 @@
-func (t T) G() {} //@rename("t", "x", tx)
-func (U T) H() {} //@rename("U", "v", Uv)
+func (v T) G() {} //@rename("t", "x", tx)
+func (v T) H() {} //@rename("U", "v", Uv)
@@ -11,2 +11,2 @@
-func (w *T) K() {}
-func (x *A) L() {} //@rename("x", "print", xprint)
+func (v *T) K() {}
+func (v *A) L() {} //@rename("x", "print", xprint)
-- @xprint/a/a.go --
@@ -7,2 +7,2 @@
-func (t T) G() {} //@rename("t", "x", tx)
-func (U T) H() {} //@rename("U", "v", Uv)
+func (print T) G() {} //@rename("t", "x", tx)
+func (print T) H() {} //@rename("U", "v", Uv)
@@ -11,2 +11,2 @@
-func (w *T) K() {}
-func (x *A) L() {} //@rename("x", "print", xprint)
+func (print *T) K() {}
+func (print *A) L() {} //@rename("x", "print", xprint)
-- @vrefz/a/a.go --
@@ -10 +10 @@
-func (v A) J() { print(-v) } //@rename(re"-(v)", "z", vrefz)
+func (z A) J() { print(-z) } //@rename(re"-(v)", "z", vrefz)
-- b/b.go --
package b

type C[T any] int
func (r C[T]) F() {} //@rename("r", "c", rc)
func (r C[T]) G() {}

-- @rc/b/b.go --
@@ -4,2 +4,2 @@
-func (r C[T]) F() {} //@rename("r", "c", rc)
-func (r C[T]) G() {}
+func (c C[T]) F() {} //@rename("r", "c", rc)
+func (c C[T]) G() {}


================================================
FILE: gopls/internal/test/marker/testdata/rename/shadow.txt
================================================

-- shadow.go --
package shadow

func _() {
	a := true
	b, c, _ := A(), B(), D() //@renameerr("A", "a", re"shadowed"),rename("B", "b", BTob),renameerr("b", "c", re"conflict"),rename("D", "d", DTod)
	d := false
	_, _, _, _ = a, b, c, d
}

func A() int {
	return 0
}

func B() int {
	return 0
}

func D() int {
	return 0
}
-- @BTob/shadow.go --
@@ -5 +5 @@
-	b, c, _ := A(), B(), D() //@renameerr("A", "a", re"shadowed"),rename("B", "b", BTob),renameerr("b", "c", re"conflict"),rename("D", "d", DTod)
+	b, c, _ := A(), b(), D() //@renameerr("A", "a", re"shadowed"),rename("B", "b", BTob),renameerr("b", "c", re"conflict"),rename("D", "d", DTod)
@@ -14 +14 @@
-func B() int {
+func b() int {
-- @DTod/shadow.go --
@@ -5 +5 @@
-	b, c, _ := A(), B(), D() //@renameerr("A", "a", re"shadowed"),rename("B", "b", BTob),renameerr("b", "c", re"conflict"),rename("D", "d", DTod)
+	b, c, _ := A(), B(), d() //@renameerr("A", "a", re"shadowed"),rename("B", "b", BTob),renameerr("b", "c", re"conflict"),rename("D", "d", DTod)
@@ -18 +18 @@
-func D() int {
+func d() int {


================================================
FILE: gopls/internal/test/marker/testdata/rename/testy.txt
================================================

-- flags --
-ignore_extra_diags

-- testy.go --
package testy

type tt int //@rename("tt", "testyType", ttTotestyType)

func a() {
	foo := 42 //@rename("foo", "bar", fooTobar)
}
-- testy_test.go --
package testy

import "testing"

func TestSomething(t *testing.T) {
	var x int //@rename("x", "testyX", xTotestyX)
	a()       //@rename("a", "b", aTob)
}
-- @aTob/testy.go --
@@ -5 +5 @@
-func a() {
+func b() {
-- @aTob/testy_test.go --
@@ -7 +7 @@
-	a()       //@rename("a", "b", aTob)
+	b()       //@rename("a", "b", aTob)
-- @fooTobar/testy.go --
@@ -6 +6 @@
-	foo := 42 //@rename("foo", "bar", fooTobar)
+	bar := 42 //@rename("foo", "bar", fooTobar)
-- @ttTotestyType/testy.go --
@@ -3 +3 @@
-type tt int //@rename("tt", "testyType", ttTotestyType)
+type testyType int //@rename("tt", "testyType", ttTotestyType)
-- @xTotestyX/testy_test.go --
@@ -6 +6 @@
-	var x int //@rename("x", "testyX", xTotestyX)
+	var testyX int //@rename("x", "testyX", xTotestyX)


================================================
FILE: gopls/internal/test/marker/testdata/rename/typeswitch.txt
================================================
This test covers the special case of renaming a type switch var.

-- p.go --
package p

func _(x any) {
	switch y := x.(type) { //@rename("y", "z", yToZ)
	case string:
		print(y) //@rename("y", "z", yToZ)
	default:
		print(y) //@rename("y", "z", yToZ)
	}
}

-- @yToZ/p.go --
@@ -4 +4 @@
-	switch y := x.(type) { //@rename("y", "z", yToZ)
+	switch z := x.(type) { //@rename("y", "z", yToZ)
@@ -6 +6 @@
-		print(y) //@rename("y", "z", yToZ)
+		print(z) //@rename("y", "z", yToZ)
@@ -8 +8 @@
-		print(y) //@rename("y", "z", yToZ)
+		print(z) //@rename("y", "z", yToZ)


================================================
FILE: gopls/internal/test/marker/testdata/rename/unexported.txt
================================================

This test attempts to rename a.S.X to x, which would make it
inaccessible from its external test package. The rename tool
should report an error rather than wrecking the program.
See issue #59403.

-- go.mod --
module example.com
go 1.12

-- a/a.go --
package a

var S struct{ X int } //@renameerr("X", "x", oops)

-- a/a_test.go --
package a_test

import "example.com/a"

var Y = a.S.X

-- @oops --
a/a.go:3:15: renaming "X" to "x" would make it unexported
a/a_test.go:5:13:	breaking references from packages such as "example.com/a_test"


================================================
FILE: gopls/internal/test/marker/testdata/selectionrange/selectionrange.txt
================================================
This test checks selection range functionality.

-- foo.go --
package foo

import "time"

func Bar(x, y int, t time.Time) int {
	zs := []int{1, 2, 3} //@selectionrange("1", a)

	for _, z := range zs {
		x = x + z + y + zs[1] //@selectionrange("1", b)
	}

	return x + y //@selectionrange("+", c)
}
-- @a --
Ranges 0:
	5:13-5:14 "1"
	5:7-5:21 "[]int{1, 2, 3}"
	5:1-5:21 "zs := []int{1, 2, 3}"
	4:36-12:1 "{\\n\tzs := []int{...range(\"+\", c)\\n}"
	4:0-12:1 "func Bar(x, y i...range(\"+\", c)\\n}"
	0:0-12:1 "package foo\\n\\nim...range(\"+\", c)\\n}"
-- @b --
Ranges 0:
	8:21-8:22 "1"
	8:18-8:23 "zs[1]"
	8:6-8:23 "x + z + y + zs[1]"
	8:2-8:23 "x = x + z + y + zs[1]"
	7:22-9:2 "{\\n\t\tx = x + z +...ange(\"1\", b)\\n\t}"
	7:1-9:2 "for _, z := ran...ange(\"1\", b)\\n\t}"
	4:36-12:1 "{\\n\tzs := []int{...range(\"+\", c)\\n}"
	4:0-12:1 "func Bar(x, y i...range(\"+\", c)\\n}"
	0:0-12:1 "package foo\\n\\nim...range(\"+\", c)\\n}"
-- @c --
Ranges 0:
	11:8-11:13 "x + y"
	11:1-11:13 "return x + y"
	4:36-12:1 "{\\n\tzs := []int{...range(\"+\", c)\\n}"
	4:0-12:1 "func Bar(x, y i...range(\"+\", c)\\n}"
	0:0-12:1 "package foo\\n\\nim...range(\"+\", c)\\n}"


================================================
FILE: gopls/internal/test/marker/testdata/signature/generic.txt
================================================
This test checks signature help on generic signatures.

-- g.go --
package g

type M[K comparable, V any] map[K]V

// golang/go#61189: signatureHelp must handle pointer receivers.
func (m *M[K, V]) Get(k K) V {
	return (*m)[k]
}

func Get[K comparable, V any](m M[K, V], k K) V {
	return m[k]
}

func _() {
	var m M[int, string]
	_ = m.Get(0)  //@signature("(", "Get(k int) string", -1)
	_ = Get(m, 0) //@signature("0", "Get(m M[int, string], k int) string", 1)
}


================================================
FILE: gopls/internal/test/marker/testdata/signature/issue63804.txt
================================================
Regression test for #63804: conversion to built-in type caused panic.

the server's Signature method never returns an actual error,
so the best we can assert is that there is no result.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

var _ = int(123) //@signature("123", "", 0)


================================================
FILE: gopls/internal/test/marker/testdata/signature/issue69552.txt
================================================
Regression test for #69552: panic in activeParam of a builtin, when requesting
signature help outside of the argument list.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

func _() {
	_ = len([]int{}) //@signature("en", "len(v Type) int", -1)
}


================================================
FILE: gopls/internal/test/marker/testdata/signature/signature.txt
================================================
This test exercises basic tests for signature help.

-- flags --
-ignore_extra_diags

-- go.mod --
module golang.org/lsptests

go 1.18

-- signature/signature.go --
// Package signature has tests for signature help.
package signature

import (
	"bytes"
	"encoding/json"
	"math/big"
	"fmt"
)

func Foo(a string, b int) (c bool) {
	return
}

func Bar(float64, ...byte) {
}

func FooArr(a []int) {

}

func NoArgs() {
}

type myStruct struct{}

type Bar struct {
	A, B, C, D string
}

func (*myStruct) foo(e *json.Decoder) (*big.Int, error) {
	return nil, nil
}

type MyType struct{}

type MyFunc func(foo int) string

type Alias = int
type OtherAlias = int
type StringAlias = string

func AliasSlice(a []*Alias) (b Alias)                                 { return 0 }
func AliasMap(a map[*Alias]StringAlias) (b, c map[*Alias]StringAlias) { return nil, nil }
func OtherAliasMap(a, b map[Alias]OtherAlias) map[Alias]OtherAlias    { return nil }

func Qux() {
	Foo("foo", 123) //@signature(re"()\\(", "Foo(a string, b int) (c bool)", -1)
	Foo("foo", 123) //@signature(re"()123", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature(re"(),", "Foo(a string, b int) (c bool)", 0)
	Foo("foo", 123) //@signature(re"() 1", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature(re"()\\)", "Foo(a string, b int) (c bool)", 1)
	Foo("foo", 123) //@signature(re"()o", "Foo(a string, b int) (c bool)", -1)
	_ = Foo //@signature(re"()o", "Foo(a string, b int) (c bool)", -1)
	Foo //@signature(re"()o", "Foo(a string, b int) (c bool)", -1)
	Foo() //@signature(re"()\\(", "Foo(a string, b int) (c bool)", -1)

	Bar(13.37, 0x13)       //@signature(re"()13.37", "Bar(float64, ...byte)", 0)
	Bar(13.37, 0x37)       //@signature(re"()0x37", "Bar(float64, ...byte)", 1)
	Bar(13.37, 1, 2, 3, 4) //@signature(re"()4", "Bar(float64, ...byte)", 1)

	NoArgs() //@signature(re"()\\(", "NoArgs()", -1)
	NoArgs //@signature(re"()s", "NoArgs()", -1)

	fn := func(hi, there string) func(i int) rune {
		return func(int) rune { return 0 }
	}

	fn("hi", "there")    //@signature(re"()hi", "", 0)
	fn("hi", "there")    //@signature(re"(),", "fn(hi string, there string) func(i int) rune", 0)
	fn("hi", "there")(1) //@signature(re"()1", "func(i int) rune", 0)

	fnPtr := &fn
	(*fnPtr)("hi", "there") //@signature(re"(),", "func(hi string, there string) func(i int) rune", 0)

	var fnIntf any = Foo
	fnIntf.(func(string, int) bool)("hi", 123) //@signature(re"()123", "func(string, int) bool", 1)

	(&bytes.Buffer{}).Next(2) //@signature(re"()2", "Next(n int) []byte", 0)

	myFunc := MyFunc(func(n int) string { return "" })
	myFunc(123) //@signature(re"()123", "myFunc(foo int) string", 0)

	var ms myStruct
	ms.foo(nil) //@signature(re"()nil", "foo(e *json.Decoder) (*big.Int, error)", 0)

	_ = make([]int, 1, 2) //@signature(re"()2", "make(t Type, size ...int) Type", 1)

	Foo(myFunc(123), 456) //@signature(re"()o\\(", "Foo(a string, b int) (c bool)", -1)
	Foo(myFunc(123), 456) //@signature(re"()\\(m", "Foo(a string, b int) (c bool)", -1)
	Foo( myFunc(123), 456) //@signature(re"() m", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature(re"(), ", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature(re"()456", "Foo(a string, b int) (c bool)", 1)
	Foo(myFunc) //@signature(re"()\\)", "Foo(a string, b int) (c bool)", 0)
	Foo(myFunc(123), 456) //@signature(re"()\\(1", "myFunc(foo int) string", -1)
	Foo(myFunc(123), 456) //@signature(re"()123", "myFunc(foo int) string", 0)

	fmt.Println //@signature(re"()ln", "Println(a ...any) (n int, err error)", -1)
	fmt.Println(myFunc) //@signature(re"()ln", "Println(a ...any) (n int, err error)", -1)
	fmt.Println(myFunc) //@signature(re"()Func", "myFunc(foo int) string", -1)

	var hi string = "hello"
	var wl string = " world: %s"
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature(re"()Func", "myFunc(foo int) string", -1)
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature(re"()wl", "Sprintf(format string, a ...any) string", 0)
	fmt.Println(fmt.Sprintf(wl, myFunc)) //@signature(re"() m", "Sprintf(format string, a ...any) string", 1)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature(re"()Sprint", "Sprintf(format string, a ...any) string", -1)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature(re"() fmt", "Println(a ...any) (n int, err error)", 0)
	fmt.Println(hi, fmt.Sprintf(wl, myFunc)) //@signature(re"()hi", "Println(a ...any) (n int, err error)", 0)

	panic("oops!")            //@signature(re"()\\)", "panic(v any)", 0)
	println("hello", "world") //@signature(re"(),", "println(args ...Type)", 0)

	Hello(func() {
		//@signature(re"()\\/\\/", "", 0)
	})

	AliasSlice()    //@signature(re"()\\)", "AliasSlice(a []*Alias) (b Alias)", 0)
	AliasMap()      //@signature(re"()\\)", "AliasMap(a map[*Alias]StringAlias) (b map[*Alias]StringAlias, c map[*Alias]StringAlias)", 0)
	OtherAliasMap() //@signature(re"()\\)", "OtherAliasMap(a map[Alias]OtherAlias, b map[Alias]OtherAlias) map[Alias]OtherAlias", 0)

	var l []Foo
	l = append(l, Foo{ //@signature(re"(),", "append(slice []Type, elems ...Type) []Type", 0)
		A: "hello", //@signature(re"(),", "", 0)
		B: "world", //@signature(re"(),", "", 0)
	})

	FooArr([]int{1, 2, 3, 4, 5}) //@signature(re"()1", "", 0)
}

func Hello(func()) {}

-- signature/signature2.go --
package signature

func _() {
	Foo(//@signature(re"()\\/\\/", "Foo(a string, b int) (c bool)", 0)
	Foo.//@signature(re"()\\/\\/", "Foo(a string, b int) (c bool)", 0)
	Foo.//@signature(re"()oo", "Foo(a string, b int) (c bool)", 0)
}

-- signature/signature3.go --
package signature

func _() {
	Foo("hello",//@signature(re"()\\/\\/", "Foo(a string, b int) (c bool)", 1)
}

-- signature/nonsignature.go --
package signature

var x = (1) //@signature(re"()1\\)", "", 0)

-- signature/signature_test.go --
package signature_test

import (
	"testing"

	sig "golang.org/lsptests/signature"
)

func TestSignature(t *testing.T) {
	sig.AliasSlice()    //@signature(re"()\\)", "AliasSlice(a []*sig.Alias) (b sig.Alias)", 0)
	sig.AliasMap()      //@signature(re"()\\)", "AliasMap(a map[*sig.Alias]sig.StringAlias) (b map[*sig.Alias]sig.StringAlias, c map[*sig.Alias]sig.StringAlias)", 0)
	sig.OtherAliasMap() //@signature(re"()\\)", "OtherAliasMap(a map[sig.Alias]sig.OtherAlias, b map[sig.Alias]sig.OtherAlias) map[sig.Alias]sig.OtherAlias", 0)
}

-- snippets/snippets.go --
package snippets

import (
	"golang.org/lsptests/signature"
)

type CoolAlias = int //@item(CoolAlias, "CoolAlias", "int", "type")

type structy struct {
	x signature.MyType
}

func X(_ map[signature.Alias]CoolAlias) (map[signature.Alias]CoolAlias) {
	return nil
}

func _() {
	X() //@signature(re"()\\)", "X(_ map[signature.Alias]CoolAlias) map[signature.Alias]CoolAlias", 0)
	_ = signature.MyType{} //@item(literalMyType, "signature.MyType{}", "", "var")
	s := structy{
		x: //@snippet(re"() \\/\\/", literalMyType, "signature.MyType{\\}")
	}
}

-- importedcomplit/importedcomplit.go --
package importedcomplit

import (
	// TODO(rfindley): re-enable after moving to new framework
	// "golang.org/lsptests/foo"

	// import completions (separate blocks to avoid comment alignment)
	"crypto/elli" //@complete(re"i()\"", cryptoImport)

	"fm" //@complete(re"m()\"", fmtImport)

	"go/pars" //@complete(re"s()\"", parserImport)

	namedParser "go/pars" //@complete(re"s()\"", parserImport)

	"golang.org/lspte" //@complete(re"e()\"", lsptestsImport)

	"golang.org/lsptests/sign" //@complete(re"n()\"", signatureImport)

	"golang.org/lsptests/sign" //@complete(re"()ests", lsptestsImport)

	"golang.org/lsptests/signa" //@complete(re"()na", signatureImport)
)

func _() {
	var V int //@item(icVVar, "V", "int", "var")

	// TODO(rfindley): re-enable after moving to new framework
	// _ = foo.StructFoo{V} // complete("}", Value, icVVar)
}

func _() {
	var (
		aa string //@item(icAAVar, "aa", "string", "var")
		ab int    //@item(icABVar, "ab", "int", "var")
	)

	// TODO(rfindley): re-enable after moving to new framework
	// _ = foo.StructFoo{a} // complete("}", abVar, aaVar)

	var s struct {
		AA string //@item(icFieldAA, "AA", "string", "field")
		AB int    //@item(icFieldAB, "AB", "int", "field")
	}

	// TODO(rfindley): re-enable after moving to new framework
	//_ = foo.StructFoo{s.} // complete("}", icFieldAB, icFieldAA)
}

/* "fmt" */ //@item(fmtImport, "fmt", "\"fmt\"", "package")
/* "go/parser" */ //@item(parserImport, "parser", "\"go/parser\"", "package")
/* "golang.org/lsptests/signature" */ //@item(signatureImport, "signature", "\"golang.org/lsptests/signature\"", "package")
/* "golang.org/lsptests/" */ //@item(lsptestsImport, "lsptests/", "\"golang.org/lsptests/\"", "package")
/* "crypto/elliptic" */ //@item(cryptoImport, "elliptic", "\"crypto/elliptic\"", "package")


================================================
FILE: gopls/internal/test/marker/testdata/symbol/basic.txt
================================================
Basic tests of textDocument/documentSymbols.

-- settings.json --
{"analyses": {"unusedfunc": false}}

-- symbol.go --
package main

//@symbol(want)

import "io"

var _ = 1

var x = 42

var nested struct {
	nestedField struct {
		f int
	}
}

const y = 43

type Number int

type Alias = string

type NumberAlias = Number

type (
	Boolean   bool
	BoolAlias = bool
)

type Foo struct {
	Quux
	W         io.Writer
	Bar       int
	baz       string
	funcField func(int) int
}

type Quux struct {
	X, Y float64
}

type EmptyStruct struct{}

func (f Foo) Baz() string {
	return f.baz
}

func _() {}

func (q *Quux) Do() {}

func main() {
}

type Stringer interface {
	String() string
}

type ABer interface {
	B()
	A() string
}

type WithEmbeddeds interface {
	Do()
	ABer
	io.Writer
}

type EmptyInterface any

func Dunk() int { return 0 }

func dunk() {}

var _ = dunk

-- @want --
(*Quux).Do "func()"
(Foo).Baz "func() string" +2 lines
ABer "interface{...}" +3 lines
ABer.A "func() string"
ABer.B "func()"
Alias "string"
BoolAlias "bool"
Boolean "bool"
Dunk "func() int"
EmptyInterface "any"
EmptyStruct "struct{}"
Foo "struct{...}" +6 lines
Foo.Bar "int"
Foo.Quux "Quux"
Foo.W "io.Writer"
Foo.baz "string"
Foo.funcField "func(int) int"
Number "int"
NumberAlias "Number"
Quux "struct{...}" +2 lines
Quux.X "float64"
Quux.Y "float64"
Stringer "interface{...}" +2 lines
Stringer.String "func() string"
WithEmbeddeds "interface{...}" +4 lines
WithEmbeddeds.ABer "ABer"
WithEmbeddeds.Do "func()"
WithEmbeddeds.Writer "io.Writer"
dunk "func()"
main "func()" +1 lines
nested "struct{...}" +4 lines
nested.nestedField "struct{...}" +2 lines
nested.nestedField.f "int"
x ""
y ""


================================================
FILE: gopls/internal/test/marker/testdata/symbol/generic.txt
================================================
Basic tests of textDocument/documentSymbols with generics.

-- symbol.go --
//@symbol(want)

package main

type T[P any] struct {
	F P
}

type Constraint interface {
	~int | struct{ int }
	interface{ M() }
}

-- @want --
Constraint "interface{...}" +3 lines
Constraint.interface{...} ""
Constraint.interface{...}.M "func()"
Constraint.~int | struct{int} ""
T "struct{...}" +2 lines
T.F "P"


================================================
FILE: gopls/internal/test/marker/testdata/token/comment.txt
================================================
This test checks the semantic tokens in comments (golang/go#64648).

There will be doc links in the comments to reference other objects. Parse these
links and output tokens according to the referenced object types, so that the
editor can highlight them. This will help in checking the doc link errors and
reading comments in the code.

-- settings.json --
{
	"semanticTokens": true
}

-- a.go --
package p

import "strconv"

const A = 1
var B = 2

type Foo int


// [F] accept a [Foo], and print it. //@token("F", "function", "signature"),token("Foo", "type", "number")
func F(v Foo) {
	println(v)

}

/*
	[F1] print [A] and [B] //@token("F1", "function", "signature"),token("A", "variable", "readonly number"),token("B", "variable", "static number")
*/
func F1() {
	// print [A] and [B]. //@token("A", "variable", "readonly number"),token("B", "variable", "static number")
	println(A, B)
}

// [F2] use [strconv.Atoi] convert s, then print it //@token("F2", "function", "signature"),token("strconv", "namespace", ""),token("Atoi", "function", "signature")
func F2(s string) {
	a, _ := strconv.Atoi("42")
	b, _ := strconv.Atoi("42")
	println(a, b)  // this is a tail comment in F2 //hover(F2, "F2", F2)
}
-- b.go --
package p

// [F3] accept [*Foo]	//@token("F3", "function", "signature"),token("Foo", "type", "number")
func F3(v *Foo) {
	println(*v)
}

// [F4] equal [strconv.Atoi]	//@token("F4", "function", "signature"),token("strconv", "namespace", ""),token("Atoi", "function", "signature")
func F4(s string) (int, error) {
	return 0, nil
}


================================================
FILE: gopls/internal/test/marker/testdata/token/format.txt
================================================
This test checks semanticTokens for format string placeholders.

-- settings.json --
{
	"semanticTokens": true
}

-- flags --
-ignore_extra_diags

-- format.go --
package format

import "fmt"

func PrintfTests() {
	var i int
	var x float64
	fmt.Printf("%b %d %f", 3, i, x) //@ token("%b", "string", "format"), token("%d", "string", "format"),token("%f", "string", "format"),
	fmt.Printf("lit1%blit2%dlit3%flit4", 3, i, x) //@ token("%b", "string", "format"), token("%d", "string", "format"),token("%f", "string", "format"),token("lit1", "string", ""),token("lit2", "string", ""),token("lit3", "string", ""),
	fmt.Printf("%% %d lit2", 3, i, x) //@ token("%d", "string", "format"),token("%%", "string", ""),token("lit2", "string", ""),
	fmt.Printf("Hello %% \n %s, you \t%% \n have %d new m%%essages!", "Alice", 5) //@ token("%s", "string", "format"),token("%d", "string", "format")
	fmt.Printf("%d \nss \x25[2]d", 234, 123) //@ token("%d", "string", "format"),token("\\x25[2]d", "string", "format")
	fmt.Printf("start%[2]*.[1]*[3]dmiddle%send", 4, 5, 6) //@ token("%[2]*.[1]*[3]d", "string", "format"),token("start", "string", ""),token("%s", "string", "format"),token("middle", "string", ""),token("end", "string", "")
}



================================================
FILE: gopls/internal/test/marker/testdata/token/illformed.txt
================================================
This test checks semanticTokens on ill-formed code.
(Regression test for #68205.)

-- settings.json --
{
	"semanticTokens": true
}

-- flags --
-ignore_extra_diags

-- a.go --
package p

type _ <-<-chan int //@ token("<-", "operator", ""), token("chan", "keyword", "")


================================================
FILE: gopls/internal/test/marker/testdata/token/issue66809.txt
================================================
This is a regression test for #66809 (missing modifiers for
declarations of function-type variables).

-- settings.json --
{
	"semanticTokens": true
}

-- main.go --
package main

func main() {
    foo := func(x string) string { return x }	//@token("foo", "variable", "definition signature")
    _ = foo    					//@token("foo", "variable", "signature")
    foo("hello")				//@token("foo", "variable", "signature")
}


================================================
FILE: gopls/internal/test/marker/testdata/token/issue70251.txt
================================================
This is a regression test for #70251 (missing modifiers for
predeclared interfaces).

-- settings.json --
{
	"semanticTokens": true
}

-- a/a.go --
package a

var _ any   //@token("any", "type", "defaultLibrary interface")
var _ error //@token("error", "type", "defaultLibrary interface")


================================================
FILE: gopls/internal/test/marker/testdata/token/modifiers.txt
================================================
This test checks the output of semanticTokens modifiers.
(including test for #70219.)

-- settings.json --
{
	"semanticTokens": true
}

-- flags --
-ignore_extra_diags

-- standard.go --
package modifiers

func _() {
	a, b := false, true //@ token("false", "variable", "readonly defaultLibrary"), token("true", "variable", "readonly defaultLibrary")
}

const (
	c = iota //@ token("iota", "variable", "readonly defaultLibrary number")
)

-- custom.go --
package modifiers

type Foo struct{}

func _() {
	var array [2]string //@ token("array", "variable", "definition array")
	array = [2]string{"", ""} //@ token("array", "variable", "array")

	var b bool //@ token("b", "variable", "definition bool")
	b = true //@ token("b", "variable", "bool")

	var c chan string //@ token("c", "variable", "definition chan")
	c = make(chan string) //@ token("c", "variable", "chan")

	type inter interface{} //@ token("inter", "type", "definition interface")

	var m map[string]string //@ token("m", "variable", "definition map")
	m = make(map[string]string) //@ token("m", "variable", "map")

	var number int //@ token("number", "variable", "definition number")
	number = 1 //@ token("number", "variable", "number")

	var ptr *Foo //@ token("ptr", "variable", "definition pointer")
	ptr = nil //@ token("ptr", "variable", "pointer")

	var sig func(string) //@ token("sig", "variable", "definition signature")
	sig = nil //@ token("sig", "variable", "signature")

	var slice []string //@ token("slice", "variable", "definition slice")
	slice = nil //@ token("slice", "variable", "slice")

	var str string //@ token("str", "variable", "definition string")
	str = "" //@ token("str", "variable", "string")

	var foo Foo //@ token("foo", "variable", "definition struct")
	foo = Foo{} //@ token("foo", "variable", "struct")
}

// Tests of various types.Var kinds (#77344).

type T struct {
	field int //@ token("field", "property", "definition number")
}

func (recv *T) method(param int) (result int) { //@ token("recv", "parameter", "definition pointer"), token("param", "parameter", "definition number"), token("result", "variable", "definition number")
     var local int //@ token("local", "variable", "definition number")
}

var global int //@ token("global", "variable", "definition static number")


================================================
FILE: gopls/internal/test/marker/testdata/token/range.txt
================================================
This test checks the output of textDocument/semanticTokens/range.

TODO: add more assertions.

-- settings.json --
{
	"semanticTokens": true
}

-- a.go --
package p //@token("package", "keyword", "")

const C = 42 //@token("C", "variable", "definition readonly number")

func F() { //@token("F", "function", "definition signature")
	x := 2 + 3//@token("x", "variable", "definition number"),token("2", "number", ""),token("+", "operator", "")
	_ = x //@token("x", "variable", "number")
	_ = F //@token("F", "function", "signature")
}

func _() {
	// A goto's label cannot be found by ascending the syntax tree.
	goto loop //@ token("goto", "keyword", ""), token("loop", "label", "")

loop: //@token("loop", "label", "definition")
	for {
		continue loop //@ token("continue", "keyword", ""), token("loop", "label", "")
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/typedef/expression.txt
================================================
This test checks textDocument/typeDefinition over a range reveals the expression type.

-- go.mod --
module mod.com

go 1.19

-- a/a.go --
package a

import "mod.com/b"

func foo() (b.Bar, b.Baz, error) {
    return b.Bar{}, "", nil
}

func main() {
    _, _, _ = foo()//@typedef("foo()", Bar, Baz, BUILTIN)
}

-- b/b.go --
package b

type Bar struct {}//@loc(Bar, "Bar")

type Baz string//@loc(Baz, "Baz")


================================================
FILE: gopls/internal/test/marker/testdata/typedef/issue60544.txt
================================================
Regression test for golang/go#60544.

-- go.mod --
module mod.com

go 1.19
-- main.go --
package main

func F[T comparable]() {}//@typedef(re"comparable()", BUILTIN)


================================================
FILE: gopls/internal/test/marker/testdata/typedef/typedef.txt
================================================
This test exercises the textDocument/typeDefinition action.

-- typedef.go --
package typedef

type Struct struct { //@loc(Struct, "Struct"),
	Field string
}

type Int int //@loc(Int, "Int")

func _() {
	var (
		value Struct
		point *Struct
	)
	_ = value //@typedef(re"value()", Struct)
	_ = point //@typedef(re"point()", Struct)

	var (
		array   [3]Struct
		slice   []Struct
		ch      chan Struct
		complex [3]chan *[5][]Int
	)
	_ = array   //@typedef(re"array()", Struct)
	_ = slice   //@typedef(re"slice()", Struct)
	_ = ch      //@typedef(re"ch()", Struct)
	_ = complex //@typedef(re"complex()", Int)

	var s struct {
		x struct {
			xx struct {
				field1 []Struct
				field2 []Int
			}
		}
	}
	_ = s.x.xx.field1 //@typedef(re"field1()", Struct)
	_ = s.x.xx.field2 //@typedef(re"field2()", Int)
}

// type def returns function return types' location.

func F1() Int                              { return 0 }
func F2() error                            { return nil }
func F3() (Int, float64)                   { return 0, 0 }
func F4() (Int, error)                     { return 0, nil }
func F5() (Struct, int, bool, error)       { return Struct{}, 0, false, nil }
func F6() (**int, Int, bool, *error)       { return nil, 0, false, nil }
func F7() (int, float64, error, Struct)    { return 0, 0, nil, Struct{} }
func F8() (int, float64, ***Struct, error) { return 0, 0, nil, nil }

// type def returns error.

func E1() {}
func E2() (int, bool) { return 0, true }

func _() {
	F1() //@typedef(re"F1()", Int)
	F2() //@typedef(re"F2()", BUILTIN)
	F3() //@typedef(re"F3()", Int, BUILTIN)
	F4() //@typedef(re"F4()", Int, BUILTIN)
	F5() //@typedef(re"F5()", Struct, BUILTIN, BUILTIN, BUILTIN)
	F6() //@typedef(re"F6()", BUILTIN, Int, BUILTIN, BUILTIN)
	F7() //@typedef(re"F7()", BUILTIN, BUILTIN, BUILTIN, Struct)
	F8() //@typedef(re"F8()", BUILTIN, BUILTIN, Struct, BUILTIN)

	E1() //@typedef(re"E1()", err="cannot find type name(s)")
	E2() //@typedef(re"E2()", BUILTIN, BUILTIN)

	f := func() Int { return 0 }
	f() //@typedef(re"f()", Int)
}

// https://github.com/golang/go/issues/38589#issuecomment-620350922
func _() {
	type myFunc func(int) Int //@loc(myFunc, "myFunc")

	var foo myFunc
	_ = foo() //@typedef(re"foo()", myFunc), diag(")", re"not enough arguments")
}

func _() {
	// Any expression is fair game for typeDefinition;
	// it needn't be a referring identifier.
	// In this example it's the r-paren of a call expr.
	func() Struct {
		panic(0)
	}() //@typedef(re"\\)()", Struct)

	// And in this one, it's the composite literal enclosing the
	// KeyValueExpr denoted by the colon (which must not be adjacent
	// to either they key or the value!).
	_ = Struct{Field  :  ""} //@typedef(re":", Struct)
}

// edge case: type-switch implicits.
// y in "switch y" has no type; use x instead.
func _(x any) {
	switch y := x.(type) { //@typedef(re"y()", BUILTIN)
	case Int:
		_ = y //@typedef(re"y()", Int)
	case Struct:
		_ = y //@typedef(re"y()", Struct)
	}
}


================================================
FILE: gopls/internal/test/marker/testdata/typehierarchy/basic.txt
================================================
Basic test of type hierarchy.

We pose the same queries across two identical packages to exercise
the local and global algorithms.

TODO(adonovan): test other properties of the result, such as kind.

-- go.mod --
module example.com
go 1.18

-- a/a.go --
package a

type I interface { F() } //@ loc(I, "I")

type J interface { F(); G() } //@ loc(J, "J")

type S int  //@ loc(S, "S")

func (S) F() {}
func (S) G() {}

//@subtypes(S)
//@subtypes(I, J, S, BI, BJ, BS)
//@subtypes(J, S, BJ, BS)

//@supertypes(S, I, J, BI, BJ)
//@supertypes(I, BI)
//@supertypes(J, I, BI, BJ)

-- b/b.go --
package b

type BI interface { F() } //@ loc(BI, "BI")

type BJ interface { F(); G() } //@ loc(BJ, "BJ")

type BS int  //@ loc(BS, "BS")

func (BS) F() {}
func (BS) G() {}

//@subtypes(BS)
//@subtypes(BI, BJ, BS, I, J, S)
//@subtypes(BJ, BS, J, S)

//@supertypes(BS, BI, BJ, I, J)
//@supertypes(BI, I)
//@supertypes(BJ, BI, I, J)


================================================
FILE: gopls/internal/test/marker/testdata/workfile/godebug.txt
================================================
This test basic gopls functionality in a workspace with a godebug
directive in its modfile.

We use panicnil from go1.21 as an arbitrary GODEBUG; if it goes away,
pick another from https://go.dev/doc/godebug#history.

-- flags --
-min_go_command=go1.23

-- a/go.work --
go 1.23

use .

godebug (
	panicnil=0
)
godebug panicnil=1

-- a/go.mod --
module example.com/a

go 1.23

-- a/a.go --
package a

import "example.com/a/b"

const A = b.B //@def("B", B)

-- a/b/b.go --
package b

const B = 42 //@loc(B, "B")

-- format/go.work --
go 1.23 //@format(formatted)

use .

godebug (
panicnil=0
)
godebug     panicnil=1

-- @formatted --
go 1.23 //@format(formatted)

use .

godebug (
	panicnil=0
)

godebug panicnil=1
-- format/go.mod --
module example.com/format

go 1.23

-- format/p.go --
package format


================================================
FILE: gopls/internal/test/marker/testdata/workfile/godebug_bad.txt
================================================
This test checks that we surface the error for unexpected godebug values.

TODO(golang/go#67623): the diagnostic should be on the bad godebug value.

-- flags --
-min_go_command=go1.23
-errors_ok

-- go.work --
go 1.23

use .

godebug (
	panicnull=0 // misspelled
)
godebug panicnil=1

-- go.mod --
module example.com/m //@diag("module", re`unknown godebug "panicnull"`)

go 1.23


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/allscope.txt
================================================
This test verifies behavior when "symbolScope" is set to "all".

-- settings.json --
{
	"symbolStyle": "full",
	"symbolMatcher": "casesensitive",
	"symbolScope": "all"
}

-- go.mod --
module mod.test/symbols

go 1.18

-- query.go --
package symbols

//@workspacesymbol("fmt.Println", println)

-- fmt/fmt.go --
package fmt

import "fmt"

func Println(s string) {
	fmt.Println(s)
}
-- @println --
fmt/fmt.go:5:6-13 mod.test/symbols/fmt.Println Function
<external> fmt.Println Function


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/caseinsensitive.txt
================================================
This file contains test for symbol matches using the caseinsensitive matcher.

-- settings.json --
{
	"symbolMatcher": "caseinsensitive"
}

-- go.mod --
module mod.test/caseinsensitive

go 1.18

-- p.go --
package caseinsensitive

//@workspacesymbol("", blank)
//@workspacesymbol("randomgophervar", randomgophervar)

var RandomGopherVariableA int
var randomgopherVariableB int
var RandomGopherOtherVariable int

var _ = randomgopherVariableB // pacify unusedfunc

-- @blank --
-- @randomgophervar --
p.go:6:5-26 RandomGopherVariableA Variable
p.go:7:5-26 randomgopherVariableB Variable


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/casesensitive.txt
================================================
This file contains tests for symbol matches using the casesensitive matcher.

For historical reasons, it also verifies general behavior of the symbol search.

-- settings.json --
{
	"symbolMatcher": "casesensitive",
	"analyses": {"unusedfunc": false}
}

-- go.mod --
module mod.test/casesensitive

go 1.18

-- main.go --
package main

//@workspacesymbol("main.main", main)
//@workspacesymbol("p.Message", Message)
//@workspacesymbol("main.myvar", myvar)
//@workspacesymbol("main.myType", myType)
//@workspacesymbol("main.myType.Blahblah", blahblah)
//@workspacesymbol("main.myStruct", myStruct)
//@workspacesymbol("main.myStruct.myStructField", myStructField)
//@workspacesymbol("main.myInterface", myInterface)
//@workspacesymbol("main.myInterface.DoSomeCoolStuff", DoSomeCoolStuff)
//@workspacesymbol("main.embed.myStruct", embeddedStruct)
//@workspacesymbol("main.embed.nestedStruct.nestedStruct2.int", int)
//@workspacesymbol("main.embed.nestedInterface.myInterface", nestedInterface)
//@workspacesymbol("main.embed.nestedInterface.nestedMethod", nestedMethod)
//@workspacesymbol("dunk", dunk)
//@workspacesymbol("Dunk", Dunk)

import (
	"encoding/json"
	"fmt"
)

func main() { // function
	fmt.Println("Hello")
}

var myvar int // variable

type myType string // basic type

type myDecoder json.Decoder // to use the encoding/json import

func (m *myType) Blahblah() {} // method

type myStruct struct { // struct type
	myStructField int // struct field
}

type myInterface interface { // interface
	DoSomeCoolStuff() string // interface method
}

type embed struct {
	myStruct

	nestedStruct struct {
		nestedField int

		nestedStruct2 struct {
			int
		}
	}

	nestedInterface interface {
		myInterface
		nestedMethod()
	}
}

func Dunk() int { return 0 }

func dunk() {}

var _ = dunk

-- p/p.go --
package p

const Message = "Hello World." // constant
-- @DoSomeCoolStuff --
main.go:41:2-17 main.myInterface.DoSomeCoolStuff Method
-- @Dunk --
main.go:61:6-10 Dunk Function
-- @Message --
p/p.go:3:7-14 p.Message Constant
-- @blahblah --
main.go:34:18-26 main.myType.Blahblah Method
-- @dunk --
main.go:63:6-10 dunk Function
-- @int --
main.go:51:4-7 main.embed.nestedStruct.nestedStruct2.int Field
-- @main --
main.go:24:6-10 main.main Function
-- @myInterface --
main.go:40:6-17 main.myInterface Interface
main.go:41:2-17 main.myInterface.DoSomeCoolStuff Method
-- @myStruct --
main.go:36:6-14 main.myStruct Struct
main.go:37:2-15 main.myStruct.myStructField Field
-- @myStructField --
main.go:37:2-15 main.myStruct.myStructField Field
-- @myType --
main.go:30:6-12 main.myType Class
main.go:34:18-26 main.myType.Blahblah Method
-- @myvar --
main.go:28:5-10 main.myvar Variable
-- @nestedInterface --
main.go:56:3-14 main.embed.nestedInterface.myInterface Interface
-- @nestedMethod --
main.go:57:3-15 main.embed.nestedInterface.nestedMethod Method
-- @embeddedStruct --
main.go:45:2-10 main.embed.myStruct Field


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/issue44806.txt
================================================
This test verifies the fix for the crash encountered in golang/go#44806.

-- go.mod --
module mod.test/symbol

go 1.18
-- symbol.go --
package symbol

//@workspacesymbol("M", M)

type T struct{}

// We should accept all valid receiver syntax when scanning symbols.
func (*(T)) M1() {}
func (*T) M2()   {}
func (T) M3()    {}
func ((T)) M4()    {}
func ((*T)) M5()   {}

-- @M --
symbol.go:8:13-15 T.M1 Method
symbol.go:9:11-13 T.M2 Method
symbol.go:10:10-12 T.M3 Method
symbol.go:11:12-14 T.M4 Method
symbol.go:12:13-15 T.M5 Method
symbol.go:5:6-7 symbol.T Struct


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/workspacesymbol.txt
================================================
This test contains tests for basic functionality of the workspace/symbol
request.

TODO(rfindley): add a test for the legacy 'fuzzy' symbol matcher using setting ("symbolMatcher": "fuzzy"). This test uses the default matcher ("fastFuzzy").

-- flags --
-ignore_extra_diags

-- go.mod --
module mod.test/symbols

go 1.18

-- query.go --
package symbols

//@workspacesymbol("rgop", rgop)
//@workspacesymbol("randoma", randoma)
//@workspacesymbol("randomb", randomb)

-- a/a.go --
package a

var RandomGopherVariableA = "a"

const RandomGopherConstantA = "a"

const (
	randomgopherinvariable = iota
)

-- a/a_test.go --
package a

var RandomGopherTestVariableA = "a"

-- a/a_x_test.go --
package a_test

var RandomGopherXTestVariableA = "a"

-- b/b.go --
package b

var RandomGopherVariableB = "b"

type RandomGopherStructB struct {
	Bar int
}

-- @rgop --
b/b.go:5:6-25 RandomGopherStructB Struct
a/a.go:5:7-28 RandomGopherConstantA Constant
a/a.go:3:5-26 RandomGopherVariableA Variable
b/b.go:3:5-26 RandomGopherVariableB Variable
a/a_test.go:3:5-30 RandomGopherTestVariableA Variable
a/a_x_test.go:3:5-31 RandomGopherXTestVariableA Variable
a/a.go:8:2-24 randomgopherinvariable Constant
b/b.go:6:2-5 RandomGopherStructB.Bar Field
-- @randoma --
a/a.go:5:7-28 RandomGopherConstantA Constant
a/a.go:3:5-26 RandomGopherVariableA Variable
b/b.go:3:5-26 RandomGopherVariableB Variable
a/a.go:8:2-24 randomgopherinvariable Constant
a/a_test.go:3:5-30 RandomGopherTestVariableA Variable
a/a_x_test.go:3:5-31 RandomGopherXTestVariableA Variable
b/b.go:6:2-5 RandomGopherStructB.Bar Field
-- @randomb --
b/b.go:5:6-25 RandomGopherStructB Struct
a/a.go:3:5-26 RandomGopherVariableA Variable
b/b.go:3:5-26 RandomGopherVariableB Variable
a/a.go:8:2-24 randomgopherinvariable Constant
a/a_test.go:3:5-30 RandomGopherTestVariableA Variable
a/a_x_test.go:3:5-31 RandomGopherXTestVariableA Variable
b/b.go:6:2-5 RandomGopherStructB.Bar Field


================================================
FILE: gopls/internal/test/marker/testdata/workspacesymbol/wsscope.txt
================================================
This test verifies behavior when "symbolScope" is set to "workspace".

-- settings.json --
{
	"symbolStyle": "full",
	"symbolMatcher": "casesensitive",
	"symbolScope": "workspace"
}

-- go.mod --
module mod.test/symbols

go 1.18

-- query.go --
package symbols

//@workspacesymbol("fmt.Println", println)

-- fmt/fmt.go --
package fmt

import "fmt"

func Println(s string) {
	fmt.Println(s)
}
-- @println --
fmt/fmt.go:5:6-13 mod.test/symbols/fmt.Println Function


================================================
FILE: gopls/internal/test/marker/testdata/zeroconfig/adhoc.txt
================================================
This test checks that gopls works with multiple ad-hoc packages, which lack
a go.mod file.

We should be able to import standard library packages, get diagnostics, and
reference symbols defined in the same directory.

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println(mainMsg) //@def("mainMsg", mainMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}
-- main2.go --
package main

const mainMsg = "main" //@loc(mainMsg, "mainMsg")

-- a/a.go --
package a

import "fmt"

func _() {
	fmt.Println(aMsg) //@def("aMsg", aMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- a/a2.go --
package a

const aMsg = "a" //@loc(aMsg, "aMsg")

-- b/b.go --
package b

import "fmt"

func _() {
	fmt.Println(bMsg) //@def("bMsg", bMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- b/b2.go --
package b

const bMsg = "b" //@loc(bMsg, "bMsg")


================================================
FILE: gopls/internal/test/marker/testdata/zeroconfig/dynamicports.txt
================================================
This test checks that the zero-config algorithm selects Views to cover first
class ports.

In this test, package a imports b, and b imports c. Package a contains files
constrained by go:build directives, package b contains files constrained by the
GOOS matching their file name, and package c is unconstrained. Various
assertions check that diagnostics and navigation work as expected.

-- go.mod --
module golang.org/lsptests

-- a/a.go --
package a

import "golang.org/lsptests/b"

var _ = b.F //@loc(F, "F")

-- a/linux64.go --
//go:build (linux && amd64)

package a

import "golang.org/lsptests/b"

var _ int = 1<<32 -1 // OK on 64 bit platforms. Compare linux32.go below.

var (
	_ = b.LinuxOnly   //@def("LinuxOnly", LinuxOnly)
	_ = b.DarwinOnly  //@diag("DarwinOnly", re"(undefined|declared)")
	_ = b.WindowsOnly //@diag("WindowsOnly", re"(undefined|declared)")
)

-- a/linux32.go --
//go:build (linux && 386)

package a

import "golang.org/lsptests/b"

var _ int = 1<<32 -1 //@diag("1<<32", re"overflows")

var (
	_ = b.LinuxOnly   //@def("LinuxOnly", LinuxOnly)
	_ = b.DarwinOnly  //@diag("DarwinOnly", re"(undefined|declared)")
	_ = b.WindowsOnly //@diag("WindowsOnly", re"(undefined|declared)")
)

-- a/darwin64.go --
//go:build (darwin && amd64)

package a

import "golang.org/lsptests/b"

var (
	_ = b.LinuxOnly   //@diag("LinuxOnly", re"(undefined|declared)")
	_ = b.DarwinOnly  //@def("DarwinOnly", DarwinOnly)
	_ = b.WindowsOnly //@diag("WindowsOnly", re"(undefined|declared)")
)

-- a/windows64.go --
//go:build (windows && amd64)

package a

import "golang.org/lsptests/b"

var (
	_ = b.LinuxOnly   //@diag("LinuxOnly", re"(undefined|declared)")
	_ = b.DarwinOnly  //@diag("DarwinOnly", re"(undefined|declared)")
	_ = b.WindowsOnly //@def("WindowsOnly", WindowsOnly)
)

-- b/b_other.go --
//go:build !linux && !darwin && !windows
package b

func F() {}

-- b/b_linux.go --
package b

import "golang.org/lsptests/c"

func F() { //@refs("F", "F", F)
	x := c.Common //@diag("x", re"not used"),def("Common", Common)
}

const LinuxOnly = "darwin" //@loc(LinuxOnly, "LinuxOnly")

-- b/b_darwin.go --
package b

import "golang.org/lsptests/c"

func F() { //@refs("F", "F", F)
	x := c.Common //@diag("x", re"not used"),def("Common", Common)
}

const DarwinOnly = "darwin" //@loc(DarwinOnly, "DarwinOnly")

-- b/b_windows.go --
package b

import "golang.org/lsptests/c"

func F() { //@refs("F", "F", F)
	x := c.Common //@diag("x", re"not used"),def("Common", Common)
}

const WindowsOnly = "windows" //@loc(WindowsOnly, "WindowsOnly")

-- c/c.go --
package c

const Common = 0 //@loc(Common, "Common")



================================================
FILE: gopls/internal/test/marker/testdata/zeroconfig/nested.txt
================================================
This test checks that gopls works with nested modules, including multiple
nested modules.

-- main.go --
package main

import "fmt"

func main() {
	fmt.Println(mainMsg) //@def("mainMsg", mainMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}
-- main2.go --
package main

const mainMsg = "main" //@loc(mainMsg, "mainMsg")

-- mod1/go.mod --
module golang.org/lsptests/mod1

go 1.20

-- mod1/a/a.go --
package a

import (
	"fmt"
	"golang.org/lsptests/mod1/b"
)

func _() {
	fmt.Println(b.Msg) //@def("Msg", Msg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- mod1/a/tagged.go --
//go:build tag1

// golang/go#60776: verify that we get an accurate error about build tags
// here, rather than an inaccurate error suggesting to add a go.work
// file (which won't help).
package a //@diag(re`package (a)`, re`excluded due to its build tags`)

-- mod1/b/b.go --
package b

const Msg = "1" //@loc(Msg, "Msg")

-- mod2/go.mod --
module golang.org/lsptests/mod2

require golang.org/lsptests/mod1 v0.0.1

replace golang.org/lsptests/mod1 => ../mod1

go 1.20

-- mod2/c/c.go --
package c

import (
	"fmt"
	"golang.org/lsptests/mod1/b"
)

func _() {
	fmt.Println(b.Msg) //@def("Msg", Msg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}


================================================
FILE: gopls/internal/test/marker/testdata/zeroconfig/nonworkspacemodule.txt
================================================
This test checks that gopls works with modules that aren't included in the
workspace file.

-- go.work --
go 1.20

use (
	./a
	./b
)

-- a/go.mod --
module golang.org/lsptests/a

go 1.18

-- a/a.go --
package a

import (
	"fmt"
	"golang.org/lsptests/a/lib"
)

func _() {
	fmt.Println(lib.Msg) //@def("Msg", aMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- a/lib/lib.go --
package lib

const Msg = "hi" //@loc(aMsg, "Msg")

-- b/go.mod --
module golang.org/lsptests/b

go 1.18

-- b/b.go --
package b

import (
	"fmt"
	"golang.org/lsptests/b/lib"
)

func main() {
	fmt.Println(lib.Msg) //@def("Msg", bMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- b/lib/lib.go --
package lib

const Msg = "hi" //@loc(bMsg, "Msg")

-- c/go.mod --
module golang.org/lsptests/c

go 1.18

-- c/c.go --
package c

import (
	"fmt"
	"golang.org/lsptests/c/lib"
)

func main() {
	fmt.Println(lib.Msg) //@def("Msg", cMsg)
	fmt.Println(undef) //@diag("undef", re"undefined|undeclared")
}

-- c/lib/lib.go --
package lib

const Msg = "hi" //@loc(cMsg, "Msg")


================================================
FILE: gopls/internal/util/README.md
================================================
# util

This directory is not a Go package.

Its subdirectories are for utility packages, defined as implementation
helpers (not core machinery) that are used in different ways across
the gopls codebase.

================================================
FILE: gopls/internal/util/asm/parse.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package asm provides a simple parser for Go assembly files.
package asm

import (
	"bufio"
	"bytes"
	"fmt"
	"strings"
	"unicode"
)

// Kind describes the nature of an identifier in an assembly file.
type Kind uint8

const (
	Invalid Kind = iota // reserved zero value; not used by Ident
	Ref                 // arbitrary reference to symbol or control label
	Text                // definition of TEXT (function) symbol
	Global              // definition of GLOBL (var) symbol
	Data                // initialization of GLOBL (var) symbol; effectively a reference
	Label               // definition of control label
)

func (k Kind) String() string {
	if int(k) < len(kindString) {
		return kindString[k]
	}
	return fmt.Sprintf("Kind(%d)", k)
}

var kindString = [...]string{
	Invalid: "invalid",
	Ref:     "ref",
	Text:    "text",
	Global:  "global",
	Data:    "data",
	Label:   "label",
}

// A file represents a parsed file of Go assembly language.
type File struct {
	Idents []Ident

	// TODO(adonovan): use token.File? This may be important in a
	// future in which analyzers can report diagnostics in .s files.
}

// Ident represents an identifier in an assembly file.
type Ident struct {
	Name   string // symbol name (after correcting [·∕]); Name[0]='.' => current package
	Offset int    // zero-based byte offset
	Kind   Kind
}

// End returns the identifier's end offset.
func (id Ident) End() int { return id.Offset + len(id.Name) }

// Parse extracts identifiers from Go assembly files.
// Since it is a best-effort parser, it never returns an error.
func Parse(content []byte) *File {
	var idents []Ident
	offset := 0 // byte offset of start of current line

	// TODO(adonovan) use a proper tokenizer that respects
	// comments, string literals, line continuations, etc.
	scan := bufio.NewScanner(bytes.NewReader(content))
	for ; scan.Scan(); offset += len(scan.Bytes()) + len("\n") {
		line := scan.Text()

		// Strip comments.
		if idx := strings.Index(line, "//"); idx >= 0 {
			line = line[:idx]
		}

		// Skip blank lines.
		if strings.TrimSpace(line) == "" {
			continue
		}

		// Check for label definitions (ending with colon).
		if colon := strings.IndexByte(line, ':'); colon > 0 {
			label := strings.TrimSpace(line[:colon])
			if isIdent(label) {
				idents = append(idents, Ident{
					Name:   label,
					Offset: offset + strings.Index(line, label),
					Kind:   Label,
				})
				continue
			}
		}

		// Split line into words.
		words := strings.Fields(line)
		if len(words) == 0 {
			continue
		}

		// A line of the form
		//    TEXT ·sym<ABIInternal>(SB),NOSPLIT,$12
		// declares a text symbol "·sym".
		if len(words) > 1 {
			kind := Invalid
			switch words[0] {
			case "TEXT":
				kind = Text
			case "GLOBL":
				kind = Global
			case "DATA":
				kind = Data
			}
			if kind != Invalid {
				sym := words[1]
				sym = cutBefore(sym, ",") // strip ",NOSPLIT,$12" etc
				sym = cutBefore(sym, "(") // "sym(SB)" -> "sym"
				sym = cutBefore(sym, "<") // "sym<ABIInternal>" -> "sym"
				sym = strings.TrimSpace(sym)
				if isIdent(sym) {
					// (The Index call assumes sym is not itself "TEXT" etc.)
					idents = append(idents, Ident{
						Name:   cleanup(sym),
						Kind:   kind,
						Offset: offset + strings.Index(line, sym),
					})
				}
				continue
			}
		}

		// Find references in the rest of the line.
		pos := 0
		for _, word := range words {
			// Find actual position of word within line.
			tokenPos := strings.Index(line[pos:], word)
			if tokenPos < 0 {
				panic(line)
			}
			tokenPos += pos
			pos = tokenPos + len(word)

			// Reject probable instruction mnemonics (e.g. MOV).
			if len(word) >= 2 && word[0] != '·' &&
				!strings.ContainsFunc(word, unicode.IsLower) {
				continue
			}

			if word[0] == '$' {
				word = word[1:]
				tokenPos++

				// Reject probable immediate values (e.g. "$123").
				if !strings.ContainsFunc(word, isNonDigit) {
					continue
				}
			}

			// Reject probably registers (e.g. "PC").
			if len(word) <= 3 && !strings.ContainsFunc(word, unicode.IsLower) {
				continue
			}

			// Probable identifier reference.
			//
			// TODO(adonovan): handle FP symbols correctly;
			// sym+8(FP) is essentially a comment about
			// stack slot 8, not a reference to a symbol
			// with a declaration somewhere; so they form
			// an equivalence class without a canonical
			// declaration.
			//
			// TODO(adonovan): handle pseudoregisters and field
			// references such as:
			//    MOVD	$runtime·g0(SB), g      // pseudoreg
			//    MOVD	R0, g_stackguard0(g)    // field ref

			sym := cutBefore(word, "(") // "·sym(SB)" => "sym"
			sym = cutBefore(sym, "+")   // "sym+8(FP)" => "sym"
			sym = cutBefore(sym, "<")   // "sym<ABIInternal>" =>> "sym"
			if isIdent(sym) {
				idents = append(idents, Ident{
					Name:   cleanup(sym),
					Kind:   Ref,
					Offset: offset + tokenPos,
				})
			}
		}
	}

	_ = scan.Err() // ignore scan errors

	return &File{Idents: idents}
}

// isIdent reports whether s is a valid Go assembly identifier.
func isIdent(s string) bool {
	for i, r := range s {
		if !isIdentRune(r, i) {
			return false
		}
	}
	return len(s) > 0
}

// cutBefore returns the portion of s before the first occurrence of sep, if any.
func cutBefore(s, sep string) string {
	if before, _, ok := strings.Cut(s, sep); ok {
		return before
	}
	return s
}

// cleanup converts a symbol name from assembler syntax to linker syntax.
func cleanup(sym string) string {
	return repl.Replace(sym)
}

var repl = strings.NewReplacer(
	"·", ".", // (U+00B7 MIDDLE DOT)
	"∕", "/", // (U+2215 DIVISION SLASH)
)

func isNonDigit(r rune) bool { return !unicode.IsDigit(r) }

// -- plundered from GOROOT/src/cmd/asm/internal/asm/parse.go --

// We want center dot (·) and division slash (∕) to work as identifier characters.
func isIdentRune(ch rune, i int) bool {
	if unicode.IsLetter(ch) {
		return true
	}
	switch ch {
	case '_': // Underscore; traditional.
		return true
	case '\u00B7': // Represents the period in runtime.exit. U+00B7 '·' middle dot
		return true
	case '\u2215': // Represents the slash in runtime/debug.setGCPercent. U+2215 '∕' division slash
		return true
	}
	// Digits are OK only after the first character.
	return i > 0 && unicode.IsDigit(ch)
}


================================================
FILE: gopls/internal/util/asm/parse_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package asm_test

import (
	"bytes"
	"fmt"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/util/asm"
)

// TestIdents checks that (likely) identifiers are extracted in the expected places.
func TestIdents(t *testing.T) {
	src := []byte(`
// This is a nonsense file containing a variety of syntax.

#include "foo.h"
#ifdef MACRO
DATA hello<>+0x00(SB)/64, $"Hello"
GLOBL hello<(SB), RODATA, $64
#endif

TEXT mypkg·f(SB),NOSPLIT,$0
	MOVD	R1, 16(RSP) // another comment
	MOVD	$otherpkg·data(SB), R2
	JMP	label
label:
	BL	·g(SB)

TEXT ·g(SB),NOSPLIT,$0
	MOVD	$runtime·g0(SB), g
	MOVD	R0, g_stackguard0(g)
	MOVD	R0, (g_stack+stack_lo)(g)
`[1:])
	const filename = "asm.s"
	m := protocol.NewMapper(protocol.URIFromPath(filename), src)
	file := asm.Parse(src)

	want := `
asm.s:5:6-11:	data "hello"
asm.s:6:7-12:	global "hello"
asm.s:9:6-13:	text "mypkg.f"
asm.s:11:8-21:	ref "otherpkg.data"
asm.s:12:6-11:	ref "label"
asm.s:13:1-6:	label "label"
asm.s:14:5-7:	ref ".g"
asm.s:16:6-8:	text ".g"
asm.s:17:8-18:	ref "runtime.g0"
asm.s:17:25-26:	ref "g"
asm.s:18:11-24:	ref "g_stackguard0"
`[1:]
	var buf bytes.Buffer
	for _, id := range file.Idents {
		line, col := m.OffsetLineCol8(id.Offset)
		_, endCol := m.OffsetLineCol8(id.Offset + len(id.Name))
		fmt.Fprintf(&buf, "%s:%d:%d-%d:\t%s %q\n", filename, line, col, endCol, id.Kind, id.Name)
	}
	got := buf.String()
	if got != want {
		t.Errorf("got:\n%s\nwant:\n%s\ndiff:\n%s", got, want, cmp.Diff(want, got))
	}
}


================================================
FILE: gopls/internal/util/browser/README.md
================================================
This package is a copy of cmd/internal/browser from the go distribution

================================================
FILE: gopls/internal/util/browser/browser.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package browser provides utilities for interacting with users' browsers.
package browser

import (
	"os"
	"os/exec"
	"runtime"
	"time"
)

// Commands returns a list of possible commands to use to open a url.
func Commands() [][]string {
	var cmds [][]string
	if exe := os.Getenv("BROWSER"); exe != "" {
		cmds = append(cmds, []string{exe})
	}
	switch runtime.GOOS {
	case "darwin":
		cmds = append(cmds, []string{"/usr/bin/open"})
	case "windows":
		cmds = append(cmds, []string{"cmd", "/c", "start"})
	default:
		if os.Getenv("DISPLAY") != "" {
			// xdg-open is only for use in a desktop environment.
			cmds = append(cmds, []string{"xdg-open"})
		}
	}
	cmds = append(cmds,
		[]string{"chrome"},
		[]string{"google-chrome"},
		[]string{"chromium"},
		[]string{"firefox"},
	)
	return cmds
}

// Open tries to open url in a browser and reports whether it succeeded.
func Open(url string) bool {
	for _, args := range Commands() {
		cmd := exec.Command(args[0], append(args[1:], url)...)
		if cmd.Start() == nil && appearsSuccessful(cmd, 3*time.Second) {
			return true
		}
	}
	return false
}

// appearsSuccessful reports whether the command appears to have run successfully.
// If the command runs longer than the timeout, it's deemed successful.
// If the command runs within the timeout, it's deemed successful if it exited cleanly.
func appearsSuccessful(cmd *exec.Cmd, timeout time.Duration) bool {
	errc := make(chan error, 1)
	go func() {
		errc <- cmd.Wait()
	}()

	select {
	case <-time.After(timeout):
		return true
	case err := <-errc:
		return err == nil
	}
}


================================================
FILE: gopls/internal/util/bug/bug.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package bug provides utilities for reporting internal bugs, and being
// notified when they occur.
//
// Philosophically, because gopls runs as a sidecar process that the user does
// not directly control, sometimes it keeps going on broken invariants rather
// than panicking. In those cases, bug reports provide a mechanism to alert
// developers and capture relevant metadata.
package bug

import (
	"fmt"
	"runtime"
	"runtime/debug"
	"sort"
	"sync"
	"time"

	"golang.org/x/telemetry/counter"
)

// PanicOnBugs controls whether to panic when bugs are reported.
//
// It may be set to true during testing.
//
// TODO(adonovan): should we make the default true, and
// suppress it only in the product (gopls/main.go)?
var PanicOnBugs = false

var (
	mu        sync.Mutex
	exemplars map[string]Bug
	handlers  []func(Bug)
)

// A Bug represents an unexpected event or broken invariant. They are used for
// capturing metadata that helps us understand the event.
//
// Bugs are JSON-serializable.
type Bug struct {
	File        string    // file containing the call to bug.Report
	Line        int       // line containing the call to bug.Report
	Description string    // description of the bug
	Key         string    // key identifying the bug (file:line if available)
	Stack       string    // call stack
	AtTime      time.Time // time the bug was reported
}

// Reportf reports a formatted bug message.
func Reportf(format string, args ...any) {
	report(fmt.Sprintf(format, args...))
}

// Errorf calls fmt.Errorf for the given arguments, and reports the resulting
// error message as a bug.
func Errorf(format string, args ...any) error {
	err := fmt.Errorf(format, args...)
	report(err.Error())
	return err
}

// Report records a new bug encountered on the server.
// It uses reflection to report the position of the immediate caller.
func Report(description string) {
	report(description)
}

// BugReportCount is a telemetry counter that tracks # of bug reports.
var BugReportCount = counter.NewStack("gopls/bug", 16)

func report(description string) {
	_, file, line, ok := runtime.Caller(2) // all exported reporting functions call report directly

	key := "<missing callsite>"
	if ok {
		key = fmt.Sprintf("%s:%d", file, line)
	}

	if PanicOnBugs {
		panic(fmt.Sprintf("%s: %s", key, description))
	}

	bug := Bug{
		File:        file,
		Line:        line,
		Description: description,
		Key:         key,
		Stack:       string(debug.Stack()),
		AtTime:      time.Now(),
	}

	newBug := false
	mu.Lock()
	if _, ok := exemplars[key]; !ok {
		if exemplars == nil {
			exemplars = make(map[string]Bug)
		}
		exemplars[key] = bug // capture one exemplar per key
		newBug = true
	}
	hh := handlers
	handlers = nil
	mu.Unlock()

	if newBug {
		BugReportCount.Inc()
	}
	// Call the handlers outside the critical section since a
	// handler may itself fail and call bug.Report. Since handlers
	// are one-shot, the inner call should be trivial.
	for _, handle := range hh {
		handle(bug)
	}
}

// Handle adds a handler function that will be called with the next
// bug to occur on the server. The handler only ever receives one bug.
// It is called synchronously, and should return in a timely manner.
func Handle(h func(Bug)) {
	mu.Lock()
	defer mu.Unlock()
	handlers = append(handlers, h)
}

// List returns a slice of bug exemplars -- the first bugs to occur at each
// callsite.
func List() []Bug {
	mu.Lock()
	defer mu.Unlock()

	var bugs []Bug

	for _, bug := range exemplars {
		bugs = append(bugs, bug)
	}

	sort.Slice(bugs, func(i, j int) bool {
		return bugs[i].Key < bugs[j].Key
	})

	return bugs
}


================================================
FILE: gopls/internal/util/bug/bug_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bug

import (
	"encoding/json"
	"fmt"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
)

func resetForTesting() {
	exemplars = nil
	handlers = nil
}

func TestListBugs(t *testing.T) {
	defer resetForTesting()

	Report("bad")

	wantBugs(t, "bad")

	for i := range 3 {
		Report(fmt.Sprintf("index:%d", i))
	}

	wantBugs(t, "bad", "index:0")
}

func wantBugs(t *testing.T, want ...string) {
	t.Helper()

	bugs := List()
	if got, want := len(bugs), len(want); got != want {
		t.Errorf("List(): got %d bugs, want %d", got, want)
		return
	}

	for i, b := range bugs {
		if got, want := b.Description, want[i]; got != want {
			t.Errorf("bug.List()[%d] = %q, want %q", i, got, want)
		}
	}
}

func TestBugHandler(t *testing.T) {
	defer resetForTesting()

	Report("unseen")

	// Both handlers are called, in order of registration, only once.
	var got string
	Handle(func(b Bug) { got += "1:" + b.Description })
	Handle(func(b Bug) { got += "2:" + b.Description })

	Report("seen")

	Report("again")

	if want := "1:seen2:seen"; got != want {
		t.Errorf("got %q, want %q", got, want)
	}
}

func TestBugJSON(t *testing.T) {
	b1 := Bug{
		File:        "foo.go",
		Line:        1,
		Description: "a bug",
		Key:         "foo.go:1",
		Stack:       "<stack>",
		AtTime:      time.Now(),
	}

	data, err := json.Marshal(b1)
	if err != nil {
		t.Fatal(err)
	}
	var b2 Bug
	if err := json.Unmarshal(data, &b2); err != nil {
		t.Fatal(err)
	}
	if diff := cmp.Diff(b1, b2); diff != "" {
		t.Errorf("bugs differ after JSON Marshal/Unmarshal (-b1 +b2):\n%s", diff)
	}
}


================================================
FILE: gopls/internal/util/constraints/constraint.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package constraints defines a set of useful constraints to be used
// with type parameters.
package constraints

// Copied from x/exp/constraints.

// Signed is a constraint that permits any signed integer type.
// If future releases of Go add new predeclared signed integer types,
// this constraint will be modified to include them.
type Signed interface {
	~int | ~int8 | ~int16 | ~int32 | ~int64
}

// Unsigned is a constraint that permits any unsigned integer type.
// If future releases of Go add new predeclared unsigned integer types,
// this constraint will be modified to include them.
type Unsigned interface {
	~uint | ~uint8 | ~uint16 | ~uint32 | ~uint64 | ~uintptr
}

// Integer is a constraint that permits any integer type.
// If future releases of Go add new predeclared integer types,
// this constraint will be modified to include them.
type Integer interface {
	Signed | Unsigned
}

// Float is a constraint that permits any floating-point type.
// If future releases of Go add new predeclared floating-point types,
// this constraint will be modified to include them.
type Float interface {
	~float32 | ~float64
}

// Complex is a constraint that permits any complex numeric type.
// If future releases of Go add new predeclared complex numeric types,
// this constraint will be modified to include them.
type Complex interface {
	~complex64 | ~complex128
}

// Ordered is a constraint that permits any ordered type: any type
// that supports the operators < <= >= >.
// If future releases of Go add new ordered types,
// this constraint will be modified to include them.
type Ordered interface {
	Integer | Float | ~string
}


================================================
FILE: gopls/internal/util/cursorutil/util.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package cursorutil provides utility functions for working with [inspector.Cursor].
//
// It should create no additional dependencies beyond those of Cursor
// itself, so that functions can be promoted to the public API of
// Cursor in due course.
package cursorutil

import (
	"go/ast"

	"golang.org/x/tools/go/ast/inspector"
)

// FirstEnclosing returns the first value from [cursor.Enclosing] as
// both a designated type and a [inspector.Cursor] pointing to it.
//
// It returns the zero value if it is not found.
//
// A common usage is:
//
//	call, callCur := cursorutil.FirstEnclosing[*ast.CallExpr](cur)
//	if call == nil {
//		// Not Found
//	}
func FirstEnclosing[N ast.Node](cur inspector.Cursor) (N, inspector.Cursor) {
	var typ N
	for cur := range cur.Enclosing(typ) {
		return cur.Node().(N), cur
	}
	return typ, inspector.Cursor{}
}

// Path returns the specified node followed by all its ancestors up to the file.
// Use it as an adaptor between cursors and code that works with PathEnclosingInterval.
// Ultimately all such code should be eliminated.
func Path(cur inspector.Cursor) (path []ast.Node) {
	for cur := range cur.Enclosing() {
		path = append(path, cur.Node())
	}
	return
}


================================================
FILE: gopls/internal/util/fakenet/conn.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fakenet

import (
	"io"
	"net"
	"sync"
	"time"
)

// NewConn returns a net.Conn built on top of the supplied reader and writer.
// It decouples the read and write on the conn from the underlying stream
// to enable Close to abort ones that are in progress.
// It's primary use is to fake a network connection from stdin and stdout.
func NewConn(name string, in io.ReadCloser, out io.WriteCloser) net.Conn {
	c := &fakeConn{
		name:   name,
		reader: newFeeder(in.Read),
		writer: newFeeder(out.Write),
		in:     in,
		out:    out,
	}
	go c.reader.run()
	go c.writer.run()
	return c
}

type fakeConn struct {
	name   string
	reader *connFeeder
	writer *connFeeder
	in     io.ReadCloser
	out    io.WriteCloser
}

type fakeAddr string

// connFeeder serializes calls to the source function (io.Reader.Read or
// io.Writer.Write) by delegating them to a channel. This also allows calls to
// be intercepted when the connection is closed, and cancelled early if the
// connection is closed while the calls are still outstanding.
type connFeeder struct {
	source func([]byte) (int, error)
	input  chan []byte
	result chan feedResult
	mu     sync.Mutex
	closed bool
	done   chan struct{}
}

type feedResult struct {
	n   int
	err error
}

func (c *fakeConn) Close() error {
	c.reader.close()
	c.writer.close()
	c.in.Close()
	c.out.Close()
	return nil
}

func (c *fakeConn) Read(b []byte) (n int, err error)   { return c.reader.do(b) }
func (c *fakeConn) Write(b []byte) (n int, err error)  { return c.writer.do(b) }
func (c *fakeConn) LocalAddr() net.Addr                { return fakeAddr(c.name) }
func (c *fakeConn) RemoteAddr() net.Addr               { return fakeAddr(c.name) }
func (c *fakeConn) SetDeadline(t time.Time) error      { return nil }
func (c *fakeConn) SetReadDeadline(t time.Time) error  { return nil }
func (c *fakeConn) SetWriteDeadline(t time.Time) error { return nil }
func (a fakeAddr) Network() string                     { return "fake" }
func (a fakeAddr) String() string                      { return string(a) }

func newFeeder(source func([]byte) (int, error)) *connFeeder {
	return &connFeeder{
		source: source,
		input:  make(chan []byte),
		result: make(chan feedResult),
		done:   make(chan struct{}),
	}
}

func (f *connFeeder) close() {
	f.mu.Lock()
	if !f.closed {
		f.closed = true
		close(f.done)
	}
	f.mu.Unlock()
}

func (f *connFeeder) do(b []byte) (n int, err error) {
	// send the request to the worker
	select {
	case f.input <- b:
	case <-f.done:
		return 0, io.EOF
	}
	// get the result from the worker
	select {
	case r := <-f.result:
		return r.n, r.err
	case <-f.done:
		return 0, io.EOF
	}
}

func (f *connFeeder) run() {
	var b []byte
	for {
		// wait for an input request
		select {
		case b = <-f.input:
		case <-f.done:
			return
		}
		// invoke the underlying method
		n, err := f.source(b)
		// send the result back to the requester
		select {
		case f.result <- feedResult{n: n, err: err}:
		case <-f.done:
			return
		}
	}
}


================================================
FILE: gopls/internal/util/fingerprint/fingerprint.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fingerprint defines a function to [Encode] types as strings
// with the property that identical types have equal string encodings,
// in most cases. In the remaining cases (mostly involving generic
// types), the encodings can be parsed using [Parse] into [Tree] form
// and matched using [Matches].
package fingerprint

import (
	"fmt"
	"go/types"
	"reflect"
	"strconv"
	"strings"
	"text/scanner"
)

// Encode returns an encoding of a [types.Type] such that, in
// most cases, Encode(x) == Encode(y) iff [types.Identical](x, y).
//
// For a minority of types, mostly involving type parameters, identity
// cannot be reduced to string comparison; these types are called
// "tricky", and are indicated by the boolean result.
//
// In general, computing identity correctly for tricky types requires
// the type checker. However, the fingerprint encoding can be parsed
// by [Parse] into a [Tree] form that permits simple matching sufficient
// to allow a type parameter to unify with any subtree; see [Match].
//
// In the standard library, 99.8% of package-level types have a
// non-tricky method-set. The most common exceptions are due to type
// parameters.
//
// fingerprint.Encode is defined only for the signature types of functions
// and methods. It must not be called for "untyped" basic types, nor
// the type of a generic function.
func Encode(t types.Type) (_ string, tricky bool) { return fingerprint(t) }

// A Tree is a parsed form of a fingerprint for use with [Matches].
type Tree struct{ tree sexpr }

// String returns the tree in an unspecified human-readable form.
func (tree Tree) String() string {
	var out strings.Builder
	writeSexpr(&out, tree.tree)
	return out.String()
}

// Parse parses a fingerprint into tree form.
//
// The input must have been produced by [Encode] at the same source
// version; parsing is thus infallible.
func Parse(fp string) Tree {
	return Tree{parseFingerprint(fp)}
}

// Matches reports whether two fingerprint trees match, meaning that
// under some conditions (for example, particular instantiations of
// type parameters) the two types may be identical.
func Matches(x, y Tree) bool {
	return unify(x.tree, y.tree)
}

// Fingerprint syntax
//
// The lexical syntax is essentially Lisp S-expressions:
//
//      expr = STRING | INTEGER | IDENT | '(' expr... ')'
//
// where the tokens are as defined by text/scanner.
//
// The grammar of expression forms is:
//
//      τ = IDENT                       -- named or basic type
//        | (qual STRING IDENT)         -- qualified named type
//        | (array INTEGER τ)
//        | (slice τ)
//        | (ptr τ)
//        | (chan IDENT τ)
//        | (func τ v? τ)               -- signature params, results, variadic?
//        | (map τ τ)
//        | (struct field*)
//        | (tuple τ*)
//        | (interface)                 -- nonempty interface (lossy)
//        | (typeparam INTEGER)
//        | (inst τ τ...)               -- instantiation of a named type
//
//  field = IDENT IDENT STRING τ        -- name, embedded?, tag, type

func fingerprint(t types.Type) (string, bool) {
	var buf strings.Builder
	tricky := false
	var print func(t types.Type)
	print = func(t types.Type) {
		switch t := t.(type) {
		case *types.Alias:
			print(types.Unalias(t))

		case *types.Named:
			targs := t.TypeArgs()
			if targs != nil {
				buf.WriteString("(inst ")
			}
			tname := t.Obj()
			if tname.Pkg() != nil {
				fmt.Fprintf(&buf, "(qual %q %s)", tname.Pkg().Path(), tname.Name())
			} else if tname.Name() != "error" && tname.Name() != "comparable" {
				panic(tname) // error and comparable the only named types with no package
			} else {
				buf.WriteString(tname.Name())
			}
			if targs != nil {
				for t0 := range targs.Types() {
					buf.WriteByte(' ')
					print(t0)
				}
				buf.WriteString(")")
			}

		case *types.Array:
			fmt.Fprintf(&buf, "(array %d ", t.Len())
			print(t.Elem())
			buf.WriteByte(')')

		case *types.Slice:
			buf.WriteString("(slice ")
			print(t.Elem())
			buf.WriteByte(')')

		case *types.Pointer:
			buf.WriteString("(ptr ")
			print(t.Elem())
			buf.WriteByte(')')

		case *types.Map:
			buf.WriteString("(map ")
			print(t.Key())
			buf.WriteByte(' ')
			print(t.Elem())
			buf.WriteByte(')')

		case *types.Chan:
			fmt.Fprintf(&buf, "(chan %d ", t.Dir())
			print(t.Elem())
			buf.WriteByte(')')

		case *types.Tuple:
			buf.WriteString("(tuple")
			for v := range t.Variables() {
				buf.WriteByte(' ')
				print(v.Type())
			}
			buf.WriteByte(')')

		case *types.Basic:
			// Print byte/uint8 as "byte" instead of calling
			// BasicType.String, which prints the two distinctly
			// (even though their Kinds are numerically equal).
			// Ditto for rune/int32.
			switch t.Kind() {
			case types.Byte:
				buf.WriteString("byte")
			case types.Rune:
				buf.WriteString("rune")
			case types.UnsafePointer:
				buf.WriteString(`(qual "unsafe" Pointer)`)
			default:
				if t.Info()&types.IsUntyped != 0 {
					panic("fingerprint of untyped type")
				}
				buf.WriteString(t.String())
			}

		case *types.Signature:
			buf.WriteString("(func ")
			print(t.Params())
			if t.Variadic() {
				buf.WriteString(" v")
			}
			buf.WriteByte(' ')
			print(t.Results())
			buf.WriteByte(')')

		case *types.Struct:
			// Non-empty unnamed struct types in method
			// signatures are vanishingly rare.
			buf.WriteString("(struct")
			for i := range t.NumFields() {
				f := t.Field(i)
				name := f.Name()
				if !f.Exported() {
					name = fmt.Sprintf("(qual %q %s)", f.Pkg().Path(), name)
				}

				// This isn't quite right for embedded type aliases.
				// (See types.TypeString(StructType) and #44410 for context.)
				// But this is vanishingly rare.
				fmt.Fprintf(&buf, " %s %t %q ", name, f.Embedded(), t.Tag(i))
				print(f.Type())
			}
			buf.WriteByte(')')

		case *types.Interface:
			if t.NumMethods() == 0 {
				buf.WriteString("any") // common case
			} else {
				// Interface assignability is particularly
				// tricky due to the possibility of recursion.
				// However, nontrivial interface type literals
				// are exceedingly rare in function signatures.
				//
				// TODO(adonovan): add disambiguating precision
				// (e.g. number of methods, their IDs and arities)
				// as needs arise (i.e. collisions are observed).
				tricky = true
				buf.WriteString("(interface)")
			}

		case *types.TypeParam:
			// Matching of type parameters will require
			// parsing fingerprints and unification.
			tricky = true
			fmt.Fprintf(&buf, "(%s %d)", symTypeparam, t.Index())

		default: // incl. *types.Union
			panic(t)
		}
	}

	print(t)

	return buf.String(), tricky
}

// sexpr defines the representation of a fingerprint tree.
type (
	sexpr  any // = string | int | symbol | *cons | nil
	symbol string
	cons   struct{ car, cdr sexpr }
)

// parseFingerprint returns the type encoded by fp in tree form.
//
// The input must have been produced by [fingerprint] at the same
// source version; parsing is thus infallible.
func parseFingerprint(fp string) sexpr {
	var scan scanner.Scanner
	scan.Error = func(scan *scanner.Scanner, msg string) { panic(msg) }
	scan.Init(strings.NewReader(fp))

	// next scans a token and updates tok.
	var tok rune
	next := func() { tok = scan.Scan() }

	next()

	// parse parses a fingerprint and returns its tree.
	var parse func() sexpr
	parse = func() sexpr {
		if tok == '(' {
			next()         // consume '('
			var head sexpr // empty list
			tailcdr := &head
			for tok != ')' {
				cell := &cons{car: parse()}
				*tailcdr = cell
				tailcdr = &cell.cdr
			}
			next() // consume ')'
			return head
		}

		s := scan.TokenText()
		switch tok {
		case scanner.Ident:
			next() // consume IDENT
			return symbol(s)

		case scanner.Int:
			next() // consume INT
			i, err := strconv.Atoi(s)
			if err != nil {
				panic(err)
			}
			return i

		case scanner.String:
			next() // consume STRING
			s, err := strconv.Unquote(s)
			if err != nil {
				panic(err)
			}
			return s

		default:
			panic(tok)
		}
	}

	return parse()
}

// writeSexpr formats an S-expression.
// It is provided for debugging.
func writeSexpr(out *strings.Builder, x sexpr) {
	switch x := x.(type) {
	case nil:
		out.WriteString("()")
	case string:
		fmt.Fprintf(out, "%q", x)
	case int:
		fmt.Fprintf(out, "%d", x)
	case symbol:
		out.WriteString(string(x))
	case *cons:
		out.WriteString("(")
		for {
			writeSexpr(out, x.car)
			if x.cdr == nil {
				break
			} else if cdr, ok := x.cdr.(*cons); ok {
				x = cdr
				out.WriteByte(' ')
			} else {
				// Dotted list: should never happen,
				// but support it for debugging.
				out.WriteString(" . ")
				print(x.cdr)
				break
			}
		}
		out.WriteString(")")
	default:
		panic(x)
	}
}

// unify reports whether x and y match, in the presence of type parameters.
// The constraints on type parameters are ignored, but each type parameter must
// have a consistent binding.
func unify(x, y sexpr) bool {

	// maxTypeParam returns the maximum type parameter index in x.
	var maxTypeParam func(x sexpr) int
	maxTypeParam = func(x sexpr) int {
		if i := typeParamIndex(x); i >= 0 {
			return i
		}
		if c, ok := x.(*cons); ok {
			return max(maxTypeParam(c.car), maxTypeParam(c.cdr))
		}
		return -1
	}

	// xBindings[i] is the binding for type parameter #i in x, and similarly for y.
	// Although type parameters are nominally bound to sexprs, each bindings[i]
	// is a *sexpr, so unbound variables can share a binding.
	xBindings := make([]*sexpr, maxTypeParam(x)+1)
	for i := range len(xBindings) {
		xBindings[i] = new(sexpr)
	}
	yBindings := make([]*sexpr, maxTypeParam(y)+1)
	for i := range len(yBindings) {
		yBindings[i] = new(sexpr)
	}

	// bind sets binding b to s from bindings if it does not occur in s.
	bind := func(b *sexpr, s sexpr, bindings []*sexpr) bool {
		// occurs reports whether b is present in s.
		var occurs func(s sexpr) bool
		occurs = func(s sexpr) bool {
			if j := typeParamIndex(s); j >= 0 {
				return b == bindings[j]
			}
			if c, ok := s.(*cons); ok {
				return occurs(c.car) || occurs(c.cdr)
			}
			return false
		}

		if occurs(s) {
			return false
		}
		*b = s
		return true
	}

	var uni func(x, y sexpr) bool
	uni = func(x, y sexpr) bool {
		var bx, by *sexpr
		ix := typeParamIndex(x)
		if ix >= 0 {
			bx = xBindings[ix]
		}
		iy := typeParamIndex(y)
		if iy >= 0 {
			by = yBindings[iy]
		}

		if bx != nil || by != nil {
			// If both args are type params and neither is bound, have them share a binding.
			if bx != nil && by != nil && *bx == nil && *by == nil {
				xBindings[ix] = yBindings[iy]
				return true
			}
			// Treat param bindings like original args in what follows.
			if bx != nil && *bx != nil {
				x = *bx
			}
			if by != nil && *by != nil {
				y = *by
			}
			// If the x param is unbound, bind it to y.
			if bx != nil && *bx == nil {
				return bind(bx, y, yBindings)
			}
			// If the y param is unbound, bind it to x.
			if by != nil && *by == nil {
				return bind(by, x, xBindings)
			}
			// Unify the binding of a bound parameter.
			return uni(x, y)
		}

		// Neither arg is a type param.
		if reflect.TypeOf(x) != reflect.TypeOf(y) {
			return false // type mismatch
		}
		switch x := x.(type) {
		case nil, string, int, symbol:
			return x == y
		case *cons:
			y := y.(*cons)
			if !uni(x.car, y.car) {
				return false
			}
			if x.cdr == nil {
				return y.cdr == nil
			}
			if y.cdr == nil {
				return false
			}
			return uni(x.cdr, y.cdr)
		default:
			panic(fmt.Sprintf("unify %T %T", x, y))
		}
	}
	// At least one param is bound. Unify its binding with the other.
	return uni(x, y)
}

// typeParamIndex returns the index of the type parameter,
// if x has the form "(typeparam INTEGER)", otherwise -1.
func typeParamIndex(x sexpr) int {
	if x, ok := x.(*cons); ok {
		if sym, ok := x.car.(symbol); ok && sym == symTypeparam {
			return x.cdr.(*cons).car.(int)
		}
	}
	return -1
}

const symTypeparam = "typeparam"


================================================
FILE: gopls/internal/util/fingerprint/fingerprint_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fingerprint_test

import (
	"go/types"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/gopls/internal/util/fingerprint"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// Test runs the fingerprint encoder, decoder, and printer
// on the types of all package-level symbols in gopls, and ensures
// that parse+print is lossless.
func Test(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping slow test")
	}

	cfg := &packages.Config{Mode: packages.NeedTypes}
	pkgs, err := packages.Load(cfg, "std", "golang.org/x/tools/gopls/...")
	if err != nil {
		t.Fatal(err)
	}

	// Record the fingerprint of each logical type (equivalence
	// class of types.Types) and assert that they are all equal.
	// (Non-tricky types only.)
	var fingerprints typeutil.Map

	for _, pkg := range pkgs {
		switch pkg.Types.Path() {
		case "unsafe", "builtin":
			continue
		}
		scope := pkg.Types.Scope()
		for _, name := range scope.Names() {
			obj := scope.Lookup(name)
			typ := obj.Type()

			if basic, ok := typ.(*types.Basic); ok &&
				basic.Info()&types.IsUntyped != 0 {
				continue // untyped constant
			}

			fp, tricky := fingerprint.Encode(typ) // check Type encoder doesn't panic

			// All equivalent (non-tricky) types have the same fingerprint.
			if !tricky {
				if prevfp, ok := fingerprints.At(typ).(string); !ok {
					fingerprints.Set(typ, fp)
				} else if fp != prevfp {
					t.Errorf("inconsistent fingerprints for type %v:\n- old: %s\n- new: %s",
						typ, fp, prevfp)
				}
			}

			tree := fingerprint.Parse(fp) // check parser doesn't panic
			fp2 := tree.String()          // check formatter doesn't pannic

			// A parse+print round-trip should be lossless.
			if fp != fp2 {
				t.Errorf("%s: %v: parse+print changed fingerprint:\n"+
					"was: %s\ngot: %s\ntype: %v",
					pkg.Fset.Position(obj.Pos()), obj, fp, fp2, typ)
			}
		}
	}
}

// TestMatches exercises the matching algorithm for generic types.
func TestMatches(t *testing.T) {
	const src = `
-- go.mod --
module example.com
go 1.24

-- a/a.go --
package a

type Int = int
type String = string

// Eq.Equal matches casefold.Equal.
type Eq[T any] interface { Equal(T, T) bool }
type casefold struct{}
func (casefold) Equal(x, y string) bool

// A matches AString.
type A[T any] = struct { x T }
type AString = struct { x string }

func C1[T any](int, T, ...string) T { panic(0) }
func C2[U any](int, int, ...U) bool { panic(0) }
func C3(int, bool, ...string) rune
func C4(int, bool, ...string)
func C5(int, float64, bool, string) bool
func C6(int, bool, ...string) bool

func DAny[T any](Named[T]) { panic(0) }
func DString(Named[string])
func DInt(Named[int])

type Named[T any] struct { x T }

func E1(byte) rune
func E2(uint8) int32
func E3(int8) uint32

// generic vs. generic
func F1[T any](T) { panic(0) }
func F2[T any](*T) { panic(0) }
func F3[T any](T, T) { panic(0) }
func F4[U any](U, *U) { panic(0) }
func F5[T, U any](T, U, U) { panic(0) }
func F6[T any](T, int, T) { panic(0) }
func F7[T any](bool, T, T) { panic(0) }
func F8[V any](*V, int, int) { panic(0) }
func F9[V any](V, *V, V) { panic(0) }
`
	pkg := testfiles.LoadPackages(t, txtar.Parse([]byte(src)), "./a")[0]
	scope := pkg.Types.Scope()
	for _, test := range []struct {
		a, b   string
		method string // optional field or method
		want   bool
	}{
		{"Eq", "casefold", "Equal", true},
		{"A", "AString", "", true},
		{"A", "Eq", "", false}, // completely unrelated
		{"C1", "C2", "", false},
		{"C1", "C3", "", false},
		{"C1", "C4", "", false},
		{"C1", "C5", "", false},
		{"C1", "C6", "", true},
		{"C2", "C3", "", false},
		{"C2", "C4", "", false},
		{"C3", "C4", "", false},
		{"DAny", "DString", "", true},
		{"DAny", "DInt", "", true},
		{"DString", "DInt", "", false}, // different instantiations of Named
		{"E1", "E2", "", true},         // byte and rune are just aliases
		{"E2", "E3", "", false},
		// The following tests cover all of the type param cases of unify.
		{"F1", "F2", "", true},  // F1[*int] = F2[int]
		{"F3", "F4", "", false}, // would require U identical to *U, prevented by occur check
		{"F5", "F6", "", true},  // one param is bound, the other is not
		{"F6", "F7", "", false}, // both are bound
		{"F5", "F8", "", true},  // T=*int, U=int, V=int
		{"F5", "F9", "", false}, // T is unbound, V is bound, and T occurs in V
	} {
		lookup := func(name string) types.Type {
			obj := scope.Lookup(name)
			if obj == nil {
				t.Fatalf("Lookup %s failed", name)
			}
			if test.method != "" {
				obj, _, _ = types.LookupFieldOrMethod(obj.Type(), true, pkg.Types, test.method)
				if obj == nil {
					t.Fatalf("Lookup %s.%s failed", name, test.method)
				}
			}
			return obj.Type()
		}

		check := func(sa, sb string, want bool) {
			t.Helper()

			a := lookup(sa)
			b := lookup(sb)

			afp, _ := fingerprint.Encode(a)
			bfp, _ := fingerprint.Encode(b)

			atree := fingerprint.Parse(afp)
			btree := fingerprint.Parse(bfp)

			got := fingerprint.Matches(atree, btree)
			if got != want {
				t.Errorf("a=%s b=%s method=%s: unify returned %t for these inputs:\n- %s\n- %s",
					sa, sb, test.method, got, a, b)
			}
		}

		check(test.a, test.b, test.want)
		// Matches is symmetric
		check(test.b, test.a, test.want)
		// Matches is reflexive
		check(test.a, test.a, true)
		check(test.b, test.b, true)
	}
}


================================================
FILE: gopls/internal/util/frob/frob.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package frob is a fast restricted object encoder/decoder in the
// spirit of encoding/gob.
//
// As with gob, types that recursively contain functions, channels,
// and unsafe.Pointers cannot be encoded, but frob has these
// additional restrictions:
//
//   - Interface values are not supported; this avoids the need for
//     the encoding to describe types.
//
//   - Private struct fields are ignored.
//
//   - The encoding is unspecified and subject to change, so the encoder
//     and decoder must exactly agree on their implementation and on the
//     definitions of the target types.
//
//   - Lengths (of arrays, slices, and maps) are currently assumed to
//     fit in 32 bits.
//
//   - There is no error handling. All errors are reported by panicking.
//
//   - Values are serialized as trees, not graphs, so shared subgraphs
//     are encoded repeatedly.
//
//   - No attempt is made to detect cyclic data structures.
package frob

import (
	"encoding/binary"
	"fmt"
	"math"
	"reflect"
	"sync"
)

// A Codec[T] is an immutable encoder and decoder for values of type T.
type Codec[T any] struct{ frob *frob }

// CodecFor[T] returns a codec for values of type T.
// It panics if type T is unsuitable.
func CodecFor[T any]() Codec[T] {
	frobsMu.Lock()
	defer frobsMu.Unlock()
	return Codec[T]{frobFor(reflect.TypeFor[T]())}
}

func (codec Codec[T]) Encode(v T) []byte          { return codec.frob.Encode(v) }
func (codec Codec[T]) Decode(data []byte, ptr *T) { codec.frob.Decode(data, ptr) }

var (
	frobsMu sync.Mutex
	frobs   = make(map[reflect.Type]*frob)
)

// A frob is an encoder/decoder for a specific type.
type frob struct {
	t     reflect.Type
	kind  reflect.Kind
	elems []*frob // elem (array/slice/ptr), key+value (map), fields (struct)
}

// frobFor returns the frob for a particular type.
// Precondition: caller holds frobsMu.
func frobFor(t reflect.Type) *frob {
	fr, ok := frobs[t]
	if !ok {
		fr = &frob{t: t, kind: t.Kind()}
		frobs[t] = fr

		switch fr.kind {
		case reflect.Bool,
			reflect.Int,
			reflect.Int8,
			reflect.Int16,
			reflect.Int32,
			reflect.Int64,
			reflect.Uint,
			reflect.Uint8,
			reflect.Uint16,
			reflect.Uint32,
			reflect.Uint64,
			reflect.Uintptr,
			reflect.Float32,
			reflect.Float64,
			reflect.Complex64,
			reflect.Complex128,
			reflect.String:

		case reflect.Array,
			reflect.Slice,
			reflect.Pointer:
			fr.addElem(fr.t.Elem())

		case reflect.Map:
			fr.addElem(fr.t.Key())
			fr.addElem(fr.t.Elem())

		case reflect.Struct:
			for i := 0; i < fr.t.NumField(); i++ {
				field := fr.t.Field(i)
				if field.PkgPath != "" {
					continue // skip unexported field
				}
				fr.addElem(field.Type)
			}

		default:
			// chan, func, interface, unsafe.Pointer
			panic(fmt.Sprintf("type %v is not supported by frob", fr.t))
		}
	}
	return fr
}

func (fr *frob) addElem(t reflect.Type) {
	fr.elems = append(fr.elems, frobFor(t))
}

const magic = "frob"

func (fr *frob) Encode(v any) []byte {
	rv := reflect.ValueOf(v)
	if rv.Type() != fr.t {
		panic(fmt.Sprintf("got %v, want %v", rv.Type(), fr.t))
	}
	w := &writer{}
	w.bytes([]byte(magic))
	fr.encode(w, rv)
	if uint64(len(w.data))>>32 != 0 {
		panic("too large") // includes all cases where len doesn't fit in 32 bits
	}
	return w.data
}

// encode appends the encoding of value v, whose type must be fr.t.
func (fr *frob) encode(out *writer, v reflect.Value) {
	switch fr.kind {
	case reflect.Bool:
		var b byte
		if v.Bool() {
			b = 1
		}
		out.uint8(b)
	case reflect.Int:
		out.uint64(uint64(v.Int()))
	case reflect.Int8:
		out.uint8(uint8(v.Int()))
	case reflect.Int16:
		out.uint16(uint16(v.Int()))
	case reflect.Int32:
		out.uint32(uint32(v.Int()))
	case reflect.Int64:
		out.uint64(uint64(v.Int()))
	case reflect.Uint:
		out.uint64(v.Uint())
	case reflect.Uint8:
		out.uint8(uint8(v.Uint()))
	case reflect.Uint16:
		out.uint16(uint16(v.Uint()))
	case reflect.Uint32:
		out.uint32(uint32(v.Uint()))
	case reflect.Uint64:
		out.uint64(v.Uint())
	case reflect.Uintptr:
		out.uint64(v.Uint())
	case reflect.Float32:
		out.uint32(math.Float32bits(float32(v.Float())))
	case reflect.Float64:
		out.uint64(math.Float64bits(v.Float()))
	case reflect.Complex64:
		z := complex64(v.Complex())
		out.uint32(math.Float32bits(real(z)))
		out.uint32(math.Float32bits(imag(z)))
	case reflect.Complex128:
		z := v.Complex()
		out.uint64(math.Float64bits(real(z)))
		out.uint64(math.Float64bits(imag(z)))

	case reflect.Array:
		len := v.Type().Len()
		elem := fr.elems[0]
		for i := range len {
			elem.encode(out, v.Index(i))
		}

	case reflect.Slice:
		len := v.Len()
		out.uint32(uint32(len))
		if len > 0 {
			elem := fr.elems[0]
			if elem.kind == reflect.Uint8 {
				// []byte fast path
				out.bytes(v.Bytes())
			} else {
				for i := range len {
					elem.encode(out, v.Index(i))
				}
			}
		}

	case reflect.Map:
		len := v.Len()
		out.uint32(uint32(len))
		if len > 0 {
			kfrob, vfrob := fr.elems[0], fr.elems[1]
			for iter := v.MapRange(); iter.Next(); {
				kfrob.encode(out, iter.Key())
				vfrob.encode(out, iter.Value())
			}
		}

	case reflect.Pointer:
		if v.IsNil() {
			out.uint8(0)
		} else {
			out.uint8(1)
			fr.elems[0].encode(out, v.Elem())
		}

	case reflect.String:
		len := v.Len()
		out.uint32(uint32(len))
		if len > 0 {
			out.data = append(out.data, v.String()...)
		}

	case reflect.Struct:
		for i, elem := range fr.elems {
			elem.encode(out, v.Field(i))
		}

	default:
		panic(fr.t)
	}
}

func (fr *frob) Decode(data []byte, ptr any) {
	rv := reflect.ValueOf(ptr).Elem()
	if rv.Type() != fr.t {
		panic(fmt.Sprintf("got %v, want %v", rv.Type(), fr.t))
	}
	rd := &reader{data}
	if len(data) < len(magic) || string(rd.bytes(len(magic))) != magic {
		panic("not a frob-encoded message") // (likely an empty message)
	}
	fr.decode(rd, rv)
	if len(rd.data) > 0 {
		panic("surplus bytes")
	}
}

// decode reads from in, decodes a value, and sets addr to it.
// addr must be a zero-initialized addressable variable of type fr.t.
func (fr *frob) decode(in *reader, addr reflect.Value) {
	switch fr.kind {
	case reflect.Bool:
		addr.SetBool(in.uint8() != 0)
	case reflect.Int:
		addr.SetInt(int64(in.uint64()))
	case reflect.Int8:
		addr.SetInt(int64(in.uint8()))
	case reflect.Int16:
		addr.SetInt(int64(in.uint16()))
	case reflect.Int32:
		addr.SetInt(int64(in.uint32()))
	case reflect.Int64:
		addr.SetInt(int64(in.uint64()))
	case reflect.Uint:
		addr.SetUint(in.uint64())
	case reflect.Uint8:
		addr.SetUint(uint64(in.uint8()))
	case reflect.Uint16:
		addr.SetUint(uint64(in.uint16()))
	case reflect.Uint32:
		addr.SetUint(uint64(in.uint32()))
	case reflect.Uint64:
		addr.SetUint(in.uint64())
	case reflect.Uintptr:
		addr.SetUint(in.uint64())
	case reflect.Float32:
		addr.SetFloat(float64(math.Float32frombits(in.uint32())))
	case reflect.Float64:
		addr.SetFloat(math.Float64frombits(in.uint64()))
	case reflect.Complex64:
		addr.SetComplex(complex128(complex(
			math.Float32frombits(in.uint32()),
			math.Float32frombits(in.uint32()),
		)))
	case reflect.Complex128:
		addr.SetComplex(complex(
			math.Float64frombits(in.uint64()),
			math.Float64frombits(in.uint64()),
		))

	case reflect.Array:
		len := fr.t.Len()
		for i := range len {
			fr.elems[0].decode(in, addr.Index(i))
		}

	case reflect.Slice:
		len := int(in.uint32())
		if len > 0 {
			elem := fr.elems[0]
			if elem.kind == reflect.Uint8 {
				// []byte fast path
				// (Not addr.SetBytes: we must make a copy.)
				addr.Set(reflect.AppendSlice(addr, reflect.ValueOf(in.bytes(len))))
			} else {
				addr.Set(reflect.MakeSlice(fr.t, len, len))
				for i := range len {
					elem.decode(in, addr.Index(i))
				}
			}
		}

	case reflect.Map:
		len := int(in.uint32())
		if len > 0 {
			m := reflect.MakeMapWithSize(fr.t, len)
			addr.Set(m)
			kfrob, vfrob := fr.elems[0], fr.elems[1]
			k := reflect.New(kfrob.t).Elem()
			v := reflect.New(vfrob.t).Elem()
			for range len {
				k.SetZero()
				v.SetZero()
				kfrob.decode(in, k)
				vfrob.decode(in, v)
				m.SetMapIndex(k, v)
			}
		}

	case reflect.Pointer:
		isNil := in.uint8() == 0
		if !isNil {
			ptr := reflect.New(fr.elems[0].t)
			addr.Set(ptr)
			fr.elems[0].decode(in, ptr.Elem())
		}

	case reflect.String:
		len := int(in.uint32())
		if len > 0 {
			addr.SetString(string(in.bytes(len)))
		}

	case reflect.Struct:
		for i, elem := range fr.elems {
			elem.decode(in, addr.Field(i))
		}

	default:
		panic(fr.t)
	}
}

var le = binary.LittleEndian

type reader struct{ data []byte }

func (r *reader) uint8() uint8 {
	v := r.data[0]
	r.data = r.data[1:]
	return v
}

func (r *reader) uint16() uint16 {
	v := le.Uint16(r.data)
	r.data = r.data[2:]
	return v
}

func (r *reader) uint32() uint32 {
	v := le.Uint32(r.data)
	r.data = r.data[4:]
	return v
}

func (r *reader) uint64() uint64 {
	v := le.Uint64(r.data)
	r.data = r.data[8:]
	return v
}

func (r *reader) bytes(n int) []byte {
	v := r.data[:n]
	r.data = r.data[n:]
	return v
}

type writer struct{ data []byte }

func (w *writer) uint8(v uint8)   { w.data = append(w.data, v) }
func (w *writer) uint16(v uint16) { w.data = le.AppendUint16(w.data, v) }
func (w *writer) uint32(v uint32) { w.data = le.AppendUint32(w.data, v) }
func (w *writer) uint64(v uint64) { w.data = le.AppendUint64(w.data, v) }
func (w *writer) bytes(v []byte)  { w.data = append(w.data, v...) }


================================================
FILE: gopls/internal/util/frob/frob_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package frob_test

import (
	"math"
	"reflect"
	"testing"

	"golang.org/x/tools/gopls/internal/util/frob"
)

func TestBasics(t *testing.T) {
	type Basics struct {
		A []*string
		B [2]int
		C *Basics
		D map[string]int
		E []byte
		F []string
	}
	codec := frob.CodecFor[Basics]()

	s1, s2 := "hello", "world"
	x := Basics{
		A: []*string{&s1, nil, &s2},
		B: [...]int{1, 2},
		C: &Basics{
			B: [...]int{3, 4},
			D: map[string]int{"one": 1},
		},
		E: []byte("hello"),
		F: []string{s1, s2},
	}
	var y Basics
	codec.Decode(codec.Encode(x), &y)
	if !reflect.DeepEqual(x, y) {
		t.Fatalf("bad roundtrip: got %#v, want %#v", y, x)
	}
}

func TestInts(t *testing.T) {
	type Ints struct {
		U    uint
		U8   uint8
		U16  uint16
		U32  uint32
		U64  uint64
		UP   uintptr
		I    int
		I8   int8
		I16  int16
		I32  int32
		I64  int64
		F32  float32
		F64  float64
		C64  complex64
		C128 complex128
	}
	codec := frob.CodecFor[Ints]()

	// maxima
	max1 := Ints{
		U:    math.MaxUint,
		U8:   math.MaxUint8,
		U16:  math.MaxUint16,
		U32:  math.MaxUint32,
		U64:  math.MaxUint64,
		UP:   math.MaxUint,
		I:    math.MaxInt,
		I8:   math.MaxInt8,
		I16:  math.MaxInt16,
		I32:  math.MaxInt32,
		I64:  math.MaxInt64,
		F32:  math.MaxFloat32,
		F64:  math.MaxFloat64,
		C64:  complex(math.MaxFloat32, math.MaxFloat32),
		C128: complex(math.MaxFloat64, math.MaxFloat64),
	}
	var max2 Ints
	codec.Decode(codec.Encode(max1), &max2)
	if !reflect.DeepEqual(max1, max2) {
		t.Fatalf("max: bad roundtrip: got %#v, want %#v", max2, max1)
	}

	// minima
	min1 := Ints{
		I:    math.MinInt,
		I8:   math.MinInt8,
		I16:  math.MinInt16,
		I32:  math.MinInt32,
		I64:  math.MinInt64,
		F32:  -math.MaxFloat32,
		F64:  -math.MaxFloat32,
		C64:  complex(-math.MaxFloat32, -math.MaxFloat32),
		C128: complex(-math.MaxFloat64, -math.MaxFloat64),
	}
	var min2 Ints
	codec.Decode(codec.Encode(min1), &min2)
	if !reflect.DeepEqual(min1, min2) {
		t.Fatalf("min: bad roundtrip: got %#v, want %#v", min2, min1)
	}

	// negatives (other than MinInt), to exercise conversions
	neg1 := Ints{
		I:   -1,
		I8:  -1,
		I16: -1,
		I32: -1,
		I64: -1,
	}
	var neg2 Ints
	codec.Decode(codec.Encode(neg1), &neg2)
	if !reflect.DeepEqual(neg1, neg2) {
		t.Fatalf("neg: bad roundtrip: got %#v, want %#v", neg2, neg1)
	}
}


================================================
FILE: gopls/internal/util/goversion/goversion.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package goversions defines gopls's policy for which versions of Go it supports.
package goversion

import (
	"fmt"
	"strings"
)

// Support holds information about end-of-life Go version support.
//
// Exposed for testing.
type Support struct {
	// GoVersion is the Go version to which these settings relate.
	GoVersion int

	// DeprecatedVersion is the first version of gopls that no longer supports
	// this Go version.
	//
	// If unset, the version is already deprecated.
	DeprecatedVersion string

	// InstallGoplsVersion is the latest gopls version that supports this Go
	// version without warnings.
	InstallGoplsVersion string
}

// Supported maps Go versions to the gopls version in which support will
// be deprecated, and the final gopls version supporting them without warnings.
// Keep this in sync with gopls/doc/index.md.
//
// Must be sorted in ascending order of Go version.
//
// Exposed (and mutable) for testing.
var Supported = []Support{
	{12, "", "v0.7.5"},
	{15, "", "v0.9.5"},
	{16, "", "v0.11.0"},
	{17, "", "v0.11.0"},
	{18, "", "v0.14.2"},
	{19, "v0.17.0", "v0.15.3"},
	{20, "v0.17.0", "v0.15.3"},
}

// OldestSupported is the last X in Go 1.X that this version of gopls
// supports without warnings.
//
// Exported for testing.
func OldestSupported() int {
	return Supported[len(Supported)-1].GoVersion + 1
}

// Message returns the message to display if the user has the given Go
// version, if any. The goVersion variable is the X in Go 1.X. If
// fromBuild is set, the Go version is the version used to build
// gopls. Otherwise, it is the go command version.
//
// The second component of the result indicates whether the message is
// an error, not a mere warning.
//
// If goVersion is invalid (< 0), it returns "", false.
func Message(goVersion int, fromBuild bool) (string, bool) {
	if goVersion < 0 {
		return "", false
	}

	for _, v := range Supported {
		if goVersion <= v.GoVersion {
			var msgBuilder strings.Builder

			isError := true
			if fromBuild {
				fmt.Fprintf(&msgBuilder, "Gopls was built with Go version 1.%d", goVersion)
			} else {
				fmt.Fprintf(&msgBuilder, "Found Go version 1.%d", goVersion)
			}
			if v.DeprecatedVersion != "" {
				// not deprecated yet, just a warning
				fmt.Fprintf(&msgBuilder, ", which will be unsupported by gopls %s. ", v.DeprecatedVersion)
				isError = false // warning
			} else {
				fmt.Fprint(&msgBuilder, ", which is not supported by this version of gopls. ")
			}
			fmt.Fprintf(&msgBuilder, "Please upgrade to Go 1.%d or later and reinstall gopls. ", OldestSupported())
			fmt.Fprintf(&msgBuilder, "If you can't upgrade and want this message to go away, please install gopls %s. ", v.InstallGoplsVersion)
			fmt.Fprint(&msgBuilder, "See https://go.dev/s/gopls-support-policy for more details.")

			return msgBuilder.String(), isError
		}
	}
	return "", false
}


================================================
FILE: gopls/internal/util/goversion/goversion_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package goversion_test

import (
	"fmt"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/util/goversion"
)

func TestMessage(t *testing.T) {
	// Note(rfindley): this test is a change detector, as it must be updated
	// whenever we deprecate a version.
	//
	// However, I chose to leave it as is since it gives us confidence in error
	// messages served for Go versions that we no longer support (and therefore
	// no longer run in CI).
	type test struct {
		goVersion    int
		fromBuild    bool
		wantContains []string // string fragments that we expect to see
		wantIsError  bool     // an error, not a mere warning
	}

	deprecated := func(goVersion int, lastVersion string) test {
		return test{
			goVersion: goVersion,
			fromBuild: false,
			wantContains: []string{
				fmt.Sprintf("Found Go version 1.%d", goVersion),
				"not supported",
				fmt.Sprintf("upgrade to Go 1.%d", goversion.OldestSupported()),
				fmt.Sprintf("install gopls %s", lastVersion),
			},
			wantIsError: true,
		}
	}

	tests := []test{
		{-1, false, nil, false},
		deprecated(12, "v0.7.5"),
		deprecated(13, "v0.9.5"),
		deprecated(15, "v0.9.5"),
		deprecated(16, "v0.11.0"),
		deprecated(17, "v0.11.0"),
		deprecated(18, "v0.14.2"),
		{19, false, []string{"Found Go version 1.19", "unsupported by gopls v0.17.0", "upgrade to Go 1.21", "install gopls v0.15.3"}, false},
		{19, true, []string{"Gopls was built with Go version 1.19", "unsupported by gopls v0.17.0", "upgrade to Go 1.21", "install gopls v0.15.3"}, false},
		{20, false, []string{"Found Go version 1.20", "unsupported by gopls v0.17.0", "upgrade to Go 1.21", "install gopls v0.15.3"}, false},
		{20, true, []string{"Gopls was built with Go version 1.20", "unsupported by gopls v0.17.0", "upgrade to Go 1.21", "install gopls v0.15.3"}, false},
	}

	for _, test := range tests {
		gotMsg, gotIsError := goversion.Message(test.goVersion, test.fromBuild)

		if len(test.wantContains) == 0 && gotMsg != "" {
			t.Errorf("versionMessage(%d) = %q, want \"\"", test.goVersion, gotMsg)
		}

		for _, want := range test.wantContains {
			if !strings.Contains(gotMsg, want) {
				t.Errorf("versionMessage(%d) = %q, want containing %q", test.goVersion, gotMsg, want)
			}
		}

		if gotIsError != test.wantIsError {
			t.Errorf("versionMessage(%d) isError = %v, want %v", test.goVersion, gotIsError, test.wantIsError)
		}
	}
}


================================================
FILE: gopls/internal/util/immutable/immutable.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The immutable package defines immutable wrappers around common data
// structures. These are used for additional type safety inside gopls.
//
// See the "persistent" package for copy-on-write data structures.
package immutable

import (
	"iter"
	"maps"
)

// Map is an immutable wrapper around an ordinary Go map.
type Map[K comparable, V any] struct {
	m map[K]V
}

// MapOf wraps the given Go map.
//
// The caller must not subsequently mutate the map.
func MapOf[K comparable, V any](m map[K]V) Map[K, V] {
	return Map[K, V]{m}
}

// Value returns the mapped value for k.
// It is equivalent to the commaok form of an ordinary go map, and returns
// (zero, false) if the key is not present.
func (m Map[K, V]) Value(k K) (V, bool) {
	v, ok := m.m[k]
	return v, ok
}

// Len returns the number of entries in the Map.
func (m Map[K, V]) Len() int {
	return len(m.m)
}

// All returns an iterator over each mapped (key, value) pair.
func (m Map[K, V]) All() iter.Seq2[K, V] {
	return maps.All(m.m)
}


================================================
FILE: gopls/internal/util/lru/lru.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The lru package implements a fixed-size in-memory LRU cache.
package lru

import (
	"container/heap"
	"fmt"
	"sync"
)

// A Cache is a fixed-size in-memory LRU cache, storing values of type V keyed
// by keys of type K.
type Cache[K comparable, V any] struct {
	impl *cache
}

// Get retrieves the value for the specified key.
// If the key is found, its access time is updated.
//
// The second result reports whether the key was found.
func (c *Cache[K, V]) Get(key K) (V, bool) {
	v, ok := c.impl.get(key)
	if !ok {
		var zero V
		return zero, false
	}
	// Handle untyped nil explicitly to avoid a panic in the type assertion
	// below.
	if v == nil {
		var zero V
		return zero, true
	}
	return v.(V), true
}

// Set stores a value for the specified key, using its given size to update the
// current cache size, evicting old entries as necessary to fit in the cache
// capacity.
//
// Size must be a non-negative value. If size is larger than the cache
// capacity, the value is not stored and the cache is not modified.
func (c *Cache[K, V]) Set(key K, value V, size int) {
	c.impl.set(key, value, size)
}

// New creates a new Cache with the given capacity, which must be positive.
//
// The cache capacity uses arbitrary units, which are specified during the Set
// operation.
func New[K comparable, V any](capacity int) *Cache[K, V] {
	if capacity == 0 {
		panic("zero capacity")
	}

	return &Cache[K, V]{&cache{
		capacity: capacity,
		m:        make(map[any]*entry),
	}}
}

// cache is the non-generic implementation of [Cache].
//
// (Using a generic wrapper around a non-generic impl avoids unnecessary
// "stenciling" or code duplication.)
type cache struct {
	capacity int

	mu    sync.Mutex
	used  int            // used capacity, in user-specified units
	m     map[any]*entry // k/v lookup
	lru   queue          // min-atime priority queue of *entry
	clock int64          // clock time, incremented whenever the cache is updated
}

type entry struct {
	key   any
	value any
	size  int   // caller-specified size
	atime int64 // last access / set time
	index int   // index of entry in the heap slice
}

func (c *cache) get(key any) (any, bool) {
	c.mu.Lock()
	defer c.mu.Unlock()

	c.clock++ // every access updates the clock

	if e, ok := c.m[key]; ok { // cache hit
		e.atime = c.clock
		heap.Fix(&c.lru, e.index)
		return e.value, true
	}

	return nil, false
}

func (c *cache) set(key, value any, size int) {
	if size < 0 {
		panic(fmt.Sprintf("size must be non-negative, got %d", size))
	}
	if size > c.capacity {
		return // uncacheable
	}

	c.mu.Lock()
	defer c.mu.Unlock()

	c.clock++

	// Remove the existing cache entry for key, if it exists.
	e, ok := c.m[key]
	if ok {
		c.used -= e.size
		heap.Remove(&c.lru, e.index)
		delete(c.m, key)
	}

	// Evict entries until the new value will fit.
	newUsed := c.used + size
	if newUsed < 0 {
		return // integer overflow; return silently
	}
	c.used = newUsed
	for c.used > c.capacity {
		// evict oldest entry
		e = heap.Pop(&c.lru).(*entry)
		c.used -= e.size
		delete(c.m, e.key)
	}

	// Store the new value.
	// Opt: e is evicted, so it can be reused to reduce allocation.
	if e == nil {
		e = new(entry)
	}
	e.key = key
	e.value = value
	e.size = size
	e.atime = c.clock
	c.m[e.key] = e
	heap.Push(&c.lru, e)

	if len(c.m) != len(c.lru) {
		panic("map and LRU are inconsistent")
	}
}

// -- priority queue boilerplate --

// queue is a min-atime priority queue of cache entries.
type queue []*entry

func (q queue) Len() int { return len(q) }

func (q queue) Less(i, j int) bool { return q[i].atime < q[j].atime }

func (q queue) Swap(i, j int) {
	q[i], q[j] = q[j], q[i]
	q[i].index = i
	q[j].index = j
}

func (q *queue) Push(x any) {
	e := x.(*entry)
	e.index = len(*q)
	*q = append(*q, e)
}

func (q *queue) Pop() any {
	last := len(*q) - 1
	e := (*q)[last]
	(*q)[last] = nil // aid GC
	*q = (*q)[:last]
	return e
}


================================================
FILE: gopls/internal/util/lru/lru_fuzz_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lru_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/util/lru"
)

// Simple fuzzing test for consistency.
func FuzzCache(f *testing.F) {
	type op struct {
		set        bool
		key, value byte
	}
	f.Fuzz(func(t *testing.T, data []byte) {
		var ops []op
		for len(data) >= 3 {
			ops = append(ops, op{data[0]%2 == 0, data[1], data[2]})
			data = data[3:]
		}
		cache := lru.New[byte, byte](100)
		var reference [256]byte
		for _, op := range ops {
			if op.set {
				reference[op.key] = op.value
				cache.Set(op.key, op.value, 1)
			} else {
				if v, ok := cache.Get(op.key); ok && v != reference[op.key] {
					t.Fatalf("cache.Get(%d) = %d, want %d", op.key, v, reference[op.key])
				}
			}
		}
	})
}


================================================
FILE: gopls/internal/util/lru/lru_nil_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lru_test

import (
	"testing"

	"golang.org/x/tools/gopls/internal/util/lru"
)

func TestSetUntypedNil(t *testing.T) {
	cache := lru.New[any, any](100 * 1e6)
	cache.Set(nil, nil, 1)
	if got, ok := cache.Get(nil); !ok || got != nil {
		t.Errorf("cache.Get(nil) = %v, %v, want nil, true", got, ok)
	}
}


================================================
FILE: gopls/internal/util/lru/lru_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lru_test

import (
	"bytes"
	cryptorand "crypto/rand"
	"fmt"
	"log"
	mathrand "math/rand"
	"strings"
	"testing"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/util/lru"
)

func TestCache(t *testing.T) {
	type get struct {
		key  string
		want string
	}
	type set struct {
		key, value string
	}

	tests := []struct {
		label string
		steps []any
	}{
		{"empty cache", []any{
			get{"a", ""},
			get{"b", ""},
		}},
		{"zero-length string", []any{
			set{"a", ""},
			get{"a", ""},
		}},
		{"under capacity", []any{
			set{"a", "123"},
			set{"b", "456"},
			get{"a", "123"},
			get{"b", "456"},
		}},
		{"over capacity", []any{
			set{"a", "123"},
			set{"b", "456"},
			set{"c", "78901"},
			get{"a", ""},
			get{"b", "456"},
			get{"c", "78901"},
		}},
		{"access ordering", []any{
			set{"a", "123"},
			set{"b", "456"},
			get{"a", "123"},
			set{"c", "78901"},
			get{"a", "123"},
			get{"b", ""},
			get{"c", "78901"},
		}},
	}

	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			c := lru.New[string, string](10)
			for i, step := range test.steps {
				switch step := step.(type) {
				case get:
					if got, _ := c.Get(step.key); got != step.want {
						t.Errorf("#%d: c.Get(%q) = %q, want %q", i, step.key, got, step.want)
					}
				case set:
					c.Set(step.key, step.value, len(step.value))
				}
			}
		})
	}
}

// TestConcurrency exercises concurrent access to the same entry.
//
// It is a copy of TestConcurrency from the filecache package.
func TestConcurrency(t *testing.T) {
	key := uniqueKey()
	const N = 100 // concurrency level

	// Construct N distinct values, each larger
	// than a typical 4KB OS file buffer page.
	var values [N][8192]byte
	for i := range values {
		if _, err := mathrand.Read(values[i][:]); err != nil {
			t.Fatalf("rand: %v", err)
		}
	}

	cache := lru.New[[32]byte, []byte](100 * 1e6) // 100MB cache

	// get calls Get and verifies that the cache entry
	// matches one of the values passed to Set.
	get := func(mustBeFound bool) error {
		got, ok := cache.Get(key)
		if !ok {
			if !mustBeFound {
				return nil
			}
			return fmt.Errorf("Get did not return a value")
		}
		for _, want := range values {
			if bytes.Equal(want[:], got) {
				return nil // a match
			}
		}
		return fmt.Errorf("Get returned a value that was never Set")
	}

	// Perform N concurrent calls to Set and Get.
	// All sets must succeed.
	// All gets must return nothing, or one of the Set values;
	// there is no third possibility.
	var group errgroup.Group
	for i := range values {
		v := values[i][:]
		group.Go(func() error {
			cache.Set(key, v, len(v))
			return nil
		})
		group.Go(func() error { return get(false) })
	}
	if err := group.Wait(); err != nil {
		if strings.Contains(err.Error(), "operation not supported") ||
			strings.Contains(err.Error(), "not implemented") {
			t.Skipf("skipping: %v", err)
		}
		t.Fatal(err)
	}

	// A final Get must report one of the values that was Set.
	if err := get(true); err != nil {
		t.Fatalf("final Get failed: %v", err)
	}
}

// uniqueKey returns a key that has never been used before.
func uniqueKey() (key [32]byte) {
	if _, err := cryptorand.Read(key[:]); err != nil {
		log.Fatalf("rand: %v", err)
	}
	return
}


================================================
FILE: gopls/internal/util/memoize/memoize.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package memoize defines a "promise" abstraction that enables
// memoization of the result of calling an expensive but idempotent
// function.
//
// Call p = NewPromise(f) to obtain a promise for the future result of
// calling f(), and call p.Get() to obtain that result. All calls to
// p.Get return the result of a single call of f().
// Get blocks if the function has not finished (or started).
//
// A Store is a map of arbitrary keys to promises. Use Store.Promise
// to create a promise in the store. All calls to Handle(k) return the
// same promise as long as it is in the store. These promises are
// reference-counted and must be explicitly released. Once the last
// reference is released, the promise is removed from the store.
package memoize

import (
	"context"
	"fmt"
	"reflect"
	"runtime/trace"
	"sync"
	"sync/atomic"

	"golang.org/x/tools/internal/xcontext"
)

// Function is the type of a function that can be memoized.
//
// If the arg is a RefCounted, its Acquire/Release operations are called.
//
// The argument must not materially affect the result of the function
// in ways that are not captured by the promise's key, since if
// Promise.Get is called twice concurrently, with the same (implicit)
// key but different arguments, the Function is called only once but
// its result must be suitable for both callers.
//
// The main purpose of the argument is to avoid the Function closure
// needing to retain large objects (in practice: the snapshot) in
// memory that can be supplied at call time by any caller.
type Function func(ctx context.Context, arg any) any

// A RefCounted is a value whose functional lifetime is determined by
// reference counting.
//
// Its Acquire method is called before the Function is invoked, and
// the corresponding release is called when the Function returns.
// Usually both events happen within a single call to Get, so Get
// would be fine with a "borrowed" reference, but if the context is
// cancelled, Get may return before the Function is complete, causing
// the argument to escape, and potential premature destruction of the
// value. For a reference-counted type, this requires a pair of
// increment/decrement operations to extend its life.
type RefCounted interface {
	// Acquire prevents the value from being destroyed until the
	// returned function is called.
	Acquire() func()
}

// A Promise represents the future result of a call to a function.
type Promise struct {
	debug string // for observability

	// refcount is the reference count in the containing Store, used by
	// Store.Promise. It is guarded by Store.promisesMu on the containing Store.
	refcount int32

	mu sync.Mutex

	// A Promise starts out IDLE, waiting for something to demand
	// its evaluation. It then transitions into RUNNING state.
	//
	// While RUNNING, waiters tracks the number of Get calls
	// waiting for a result, and the done channel is used to
	// notify waiters of the next state transition. Once
	// evaluation finishes, value is set, state changes to
	// COMPLETED, and done is closed, unblocking waiters.
	//
	// Alternatively, as Get calls are cancelled, they decrement
	// waiters. If it drops to zero, the inner context is
	// cancelled, computation is abandoned, and state resets to
	// IDLE to start the process over again.
	state state
	// done is set in running state, and closed when exiting it.
	done chan struct{}
	// cancel is set in running state. It cancels computation.
	cancel context.CancelFunc
	// waiters is the number of Gets outstanding.
	waiters uint
	// the function that will be used to populate the value
	function Function
	// value is set in completed state.
	value any
}

// NewPromise returns a promise for the future result of calling the
// specified function.
//
// The debug string is used to classify promises in logs and metrics.
// It should be drawn from a small set.
func NewPromise(debug string, function Function) *Promise {
	if function == nil {
		panic("nil function")
	}
	return &Promise{
		debug:    debug,
		function: function,
	}
}

type state int

const (
	stateIdle      = iota // newly constructed, or last waiter was cancelled
	stateRunning          // start was called and not cancelled
	stateCompleted        // function call ran to completion
)

// Cached returns the value associated with a promise.
//
// It will never cause the value to be generated.
// It will return the cached value, if present.
func (p *Promise) Cached() any {
	p.mu.Lock()
	defer p.mu.Unlock()
	if p.state == stateCompleted {
		return p.value
	}
	return nil
}

// Get returns the value associated with a promise.
//
// All calls to Promise.Get on a given promise return the
// same result but the function is called (to completion) at most once.
//
// If the value is not yet ready, the underlying function will be invoked.
//
// If ctx is cancelled, Get returns (nil, Canceled).
// If all concurrent calls to Get are cancelled, the context provided
// to the function is cancelled. A later call to Get may attempt to
// call the function again.
func (p *Promise) Get(ctx context.Context, arg any) (any, error) {
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	p.mu.Lock()
	switch p.state {
	case stateIdle:
		return p.run(ctx, arg)
	case stateRunning:
		return p.wait(ctx)
	case stateCompleted:
		defer p.mu.Unlock()
		return p.value, nil
	default:
		panic("unknown state")
	}
}

// run starts p.function and returns the result. p.mu must be locked.
func (p *Promise) run(ctx context.Context, arg any) (any, error) {
	childCtx, cancel := context.WithCancel(xcontext.Detach(ctx))
	p.cancel = cancel
	p.state = stateRunning
	p.done = make(chan struct{})
	function := p.function // Read under the lock

	// Make sure that the argument isn't destroyed while we're running in it.
	release := func() {}
	if rc, ok := arg.(RefCounted); ok {
		release = rc.Acquire()
	}

	go func() {
		trace.WithRegion(childCtx, fmt.Sprintf("Promise.run %s", p.debug), func() {
			defer release()
			// Just in case the function does something expensive without checking
			// the context, double-check we're still alive.
			if childCtx.Err() != nil {
				return
			}
			v := function(childCtx, arg)
			if childCtx.Err() != nil {
				return
			}

			p.mu.Lock()
			defer p.mu.Unlock()
			// It's theoretically possible that the promise has been cancelled out
			// of the run that started us, and then started running again since we
			// checked childCtx above. Even so, that should be harmless, since each
			// run should produce the same results.
			if p.state != stateRunning {
				return
			}

			p.value = v
			p.function = nil // aid GC
			p.state = stateCompleted
			close(p.done)
		})
	}()

	return p.wait(ctx)
}

// wait waits for the value to be computed, or ctx to be cancelled. p.mu must be locked.
func (p *Promise) wait(ctx context.Context) (any, error) {
	p.waiters++
	done := p.done
	p.mu.Unlock()

	select {
	case <-done:
		p.mu.Lock()
		defer p.mu.Unlock()
		if p.state == stateCompleted {
			return p.value, nil
		}
		return nil, nil
	case <-ctx.Done():
		p.mu.Lock()
		defer p.mu.Unlock()
		p.waiters--
		if p.waiters == 0 && p.state == stateRunning {
			p.cancel()
			close(p.done)
			p.state = stateIdle
			p.done = nil
			p.cancel = nil
		}
		return nil, ctx.Err()
	}
}

// An EvictionPolicy controls the eviction behavior of keys in a Store when
// they no longer have any references.
type EvictionPolicy int

const (
	// ImmediatelyEvict evicts keys as soon as they no longer have references.
	ImmediatelyEvict EvictionPolicy = iota

	// NeverEvict does not evict keys.
	NeverEvict
)

// A Store maps arbitrary keys to reference-counted promises.
//
// The zero value is a valid Store, though a store may also be created via
// NewStore if a custom EvictionPolicy is required.
type Store struct {
	evictionPolicy EvictionPolicy

	promisesMu sync.Mutex
	promises   map[any]*Promise
}

// NewStore creates a new store with the given eviction policy.
func NewStore(policy EvictionPolicy) *Store {
	return &Store{evictionPolicy: policy}
}

// Promise returns a reference-counted promise for the future result of
// calling the specified function.
//
// Calls to Promise with the same key return the same promise, incrementing its
// reference count.  The caller must call the returned function to decrement
// the promise's reference count when it is no longer needed. The returned
// function must not be called more than once.
//
// Once the last reference has been released, the promise is removed from the
// store.
func (store *Store) Promise(key any, function Function) (*Promise, func()) {
	store.promisesMu.Lock()
	p, ok := store.promises[key]
	if !ok {
		p = NewPromise(reflect.TypeOf(key).String(), function)
		if store.promises == nil {
			store.promises = map[any]*Promise{}
		}
		store.promises[key] = p
	}
	p.refcount++
	store.promisesMu.Unlock()

	var released int32
	release := func() {
		if !atomic.CompareAndSwapInt32(&released, 0, 1) {
			panic("release called more than once")
		}
		store.promisesMu.Lock()

		p.refcount--
		if p.refcount == 0 && store.evictionPolicy != NeverEvict {
			// Inv: if p.refcount > 0, then store.promises[key] == p.
			delete(store.promises, key)
		}
		store.promisesMu.Unlock()
	}

	return p, release
}

// Stats returns the number of each type of key in the store.
func (s *Store) Stats() map[reflect.Type]int {
	result := map[reflect.Type]int{}

	s.promisesMu.Lock()
	defer s.promisesMu.Unlock()

	for k := range s.promises {
		result[reflect.TypeOf(k)]++
	}
	return result
}

// DebugOnlyIterate iterates through the store and, for each completed
// promise, calls f(k, v) for the map key k and function result v.  It
// should only be used for debugging purposes.
func (s *Store) DebugOnlyIterate(f func(k, v any)) {
	s.promisesMu.Lock()
	defer s.promisesMu.Unlock()

	for k, p := range s.promises {
		if v := p.Cached(); v != nil {
			f(k, v)
		}
	}
}


================================================
FILE: gopls/internal/util/memoize/memoize_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package memoize_test

import (
	"context"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/gopls/internal/util/memoize"
)

func TestGet(t *testing.T) {
	var store memoize.Store

	evaled := 0

	h, release := store.Promise("key", func(context.Context, any) any {
		evaled++
		return "res"
	})
	defer release()
	expectGet(t, h, "res")
	expectGet(t, h, "res")
	if evaled != 1 {
		t.Errorf("got %v calls to function, wanted 1", evaled)
	}
}

func expectGet(t *testing.T, h *memoize.Promise, wantV any) {
	t.Helper()
	gotV, gotErr := h.Get(context.Background(), nil)
	if gotV != wantV || gotErr != nil {
		t.Fatalf("Get() = %v, %v, wanted %v, nil", gotV, gotErr, wantV)
	}
}

func TestNewPromise(t *testing.T) {
	calls := 0
	f := func(context.Context, any) any {
		calls++
		return calls
	}

	// All calls to Get on the same promise return the same result.
	p1 := memoize.NewPromise("debug", f)
	expectGet(t, p1, 1)
	expectGet(t, p1, 1)

	// A new promise calls the function again.
	p2 := memoize.NewPromise("debug", f)
	expectGet(t, p2, 2)
	expectGet(t, p2, 2)

	// The original promise is unchanged.
	expectGet(t, p1, 1)
}

func TestStoredPromiseRefCounting(t *testing.T) {
	var store memoize.Store
	v1 := false
	v2 := false
	p1, release1 := store.Promise("key1", func(context.Context, any) any {
		return &v1
	})
	p2, release2 := store.Promise("key2", func(context.Context, any) any {
		return &v2
	})
	expectGet(t, p1, &v1)
	expectGet(t, p2, &v2)

	expectGet(t, p1, &v1)
	expectGet(t, p2, &v2)

	p2Copy, release2Copy := store.Promise("key2", func(context.Context, any) any {
		return &v1
	})
	if p2 != p2Copy {
		t.Error("Promise returned a new value while old is not destroyed yet")
	}
	expectGet(t, p2Copy, &v2)

	release2()
	if got, want := v2, false; got != want {
		t.Errorf("after destroying first v2 ref, got %v, want %v", got, want)
	}
	release2Copy()
	if got, want := v1, false; got != want {
		t.Errorf("after destroying v2, got %v, want %v", got, want)
	}
	release1()

	p2Copy, release2Copy = store.Promise("key2", func(context.Context, any) any {
		return &v2
	})
	if p2 == p2Copy {
		t.Error("Promise returned previously destroyed value")
	}
	release2Copy()
}

func TestPromiseDestroyedWhileRunning(t *testing.T) {
	// Test that calls to Promise.Get return even if the promise is destroyed while running.

	var store memoize.Store
	c := make(chan int)

	var v int
	h, release := store.Promise("key", func(ctx context.Context, _ any) any {
		<-c
		<-c
		if err := ctx.Err(); err != nil {
			t.Errorf("ctx.Err() = %v, want nil", err)
		}
		return &v
	})

	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second) // arbitrary timeout; may be removed if it causes flakes
	defer cancel()

	var wg sync.WaitGroup
	wg.Add(1)
	var got any
	var err error
	go func() {
		got, err = h.Get(ctx, nil)
		wg.Done()
	}()

	c <- 0    // send once to enter the promise function
	release() // release before the promise function returns
	c <- 0    // let the promise function proceed

	wg.Wait()

	if err != nil {
		t.Errorf("Get() failed: %v", err)
	}
	if got != &v {
		t.Errorf("Get() = %v, want %v", got, v)
	}
}

func TestDoubleReleasePanics(t *testing.T) {
	var store memoize.Store
	_, release := store.Promise("key", func(ctx context.Context, _ any) any { return 0 })

	panicked := false

	func() {
		defer func() {
			if recover() != nil {
				panicked = true
			}
		}()
		release()
		release()
	}()

	if !panicked {
		t.Errorf("calling release() twice did not panic")
	}
}


================================================
FILE: gopls/internal/util/moremaps/maps.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package moremaps

import (
	"cmp"
	"iter"
	"maps"
	"slices"
)

// Arbitrary returns an arbitrary (key, value) entry from the map and ok is true, if
// the map is not empty. Otherwise, it returns zero values for K and V, and false.
func Arbitrary[K comparable, V any](m map[K]V) (_ K, _ V, ok bool) {
	for k, v := range m {
		return k, v, true
	}
	return
}

// Group returns a new non-nil map containing the elements of s grouped by the
// keys returned from the key func.
func Group[K comparable, V any](s []V, key func(V) K) map[K][]V {
	m := make(map[K][]V)
	for _, v := range s {
		k := key(v)
		m[k] = append(m[k], v)
	}
	return m
}

// KeySlice returns the keys of the map M, like slices.Collect(maps.Keys(m)).
func KeySlice[M ~map[K]V, K comparable, V any](m M) []K {
	r := make([]K, 0, len(m))
	for k := range m {
		r = append(r, k)
	}
	return r
}

// ValueSlice returns the values of the map M, like slices.Collect(maps.Values(m)).
func ValueSlice[M ~map[K]V, K comparable, V any](m M) []V {
	r := make([]V, 0, len(m))
	for _, v := range m {
		r = append(r, v)
	}
	return r
}

// SameKeys reports whether x and y have equal sets of keys.
func SameKeys[K comparable, V1, V2 any](x map[K]V1, y map[K]V2) bool {
	ignoreValues := func(V1, V2) bool { return true }
	return maps.EqualFunc(x, y, ignoreValues)
}

// Sorted returns an iterator over the entries of m in key order.
func Sorted[M ~map[K]V, K cmp.Ordered, V any](m M) iter.Seq2[K, V] {
	// TODO(adonovan): use maps.Sorted if proposal #68598 is accepted.
	return func(yield func(K, V) bool) {
		keys := KeySlice(m)
		slices.Sort(keys)
		for _, k := range keys {
			if !yield(k, m[k]) {
				break
			}
		}
	}
}

// SortedFunc returns an iterator over the entries of m in the key order determined by cmp.
func SortedFunc[M ~map[K]V, K comparable, V any](m M, cmp func(x, y K) int) iter.Seq2[K, V] {
	// TODO(adonovan): use maps.SortedFunc if proposal #68598 is accepted.
	return func(yield func(K, V) bool) {
		keys := KeySlice(m)
		slices.SortFunc(keys, cmp)
		for _, k := range keys {
			if !yield(k, m[k]) {
				break
			}
		}
	}
}


================================================
FILE: gopls/internal/util/moreslices/slices.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package moreslices

// Remove removes all values equal to elem from slice.
//
// The closest equivalent in the standard slices package is:
//
//	DeleteFunc(func(x T) bool { return x == elem })
func Remove[T comparable](slice []T, elem T) []T {
	out := slice[:0]
	for _, v := range slice {
		if v != elem {
			out = append(out, v)
		}
	}
	return out
}

// ConvertStrings converts a slice of type A (with underlying type string)
// to a slice of type B (with underlying type string).
func ConvertStrings[B, A ~string](input []A) []B {
	result := make([]B, len(input))
	for i, v := range input {
		result[i] = B(string(v))
	}
	return result
}


================================================
FILE: gopls/internal/util/morestrings/strings.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package morestrings

import "strings"

// CutLast is the "last" analogue of [strings.Cut].
func CutLast(s, sep string) (before, after string, ok bool) {
	if i := strings.LastIndex(s, sep); i >= 0 {
		return s[:i], s[i+len(sep):], true
	}
	return s, "", false
}


================================================
FILE: gopls/internal/util/pathutil/util.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pathutil

import (
	"path/filepath"
	"strings"
)

// InDir checks whether path is in the file tree rooted at dir.
// It checks only the lexical form of the file names.
// It does not consider symbolic links.
//
// Copied from go/src/cmd/go/internal/search/search.go.
func InDir(dir, path string) bool {
	pv := strings.ToUpper(filepath.VolumeName(path))
	dv := strings.ToUpper(filepath.VolumeName(dir))
	path = path[len(pv):]
	dir = dir[len(dv):]
	switch {
	default:
		return false
	case pv != dv:
		return false
	case len(path) == len(dir):
		if path == dir {
			return true
		}
		return false
	case dir == "":
		return path != ""
	case len(path) > len(dir):
		if dir[len(dir)-1] == filepath.Separator {
			if path[:len(dir)] == dir {
				return path[len(dir):] != ""
			}
			return false
		}
		if path[len(dir)] == filepath.Separator && path[:len(dir)] == dir {
			if len(path) == len(dir)+1 {
				return true
			}
			return path[len(dir)+1:] != ""
		}
		return false
	}
}


================================================
FILE: gopls/internal/util/persistent/map.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The persistent package defines various persistent data structures;
// that is, data structures that can be efficiently copied and modified
// in sublinear time.
package persistent

import (
	"fmt"
	"iter"
	"math/rand"
	"strings"
	"sync/atomic"

	"golang.org/x/tools/gopls/internal/util/constraints"
)

// Implementation details:
// * Each value is reference counted by nodes which hold it.
// * Each node is reference counted by its parent nodes.
// * Each map is considered a top-level parent node from reference counting perspective.
// * Each change does always effectively produce a new top level node.
//
// Functions which operate directly with nodes do have a notation in form of
// `foo(arg1:+n1, arg2:+n2) (ret1:+n3)`.
// Each argument is followed by a delta change to its reference counter.
// In case if no change is expected, the delta will be `-0`.
//
// TODO(rfindley): add Update(K, func(V, bool) V), as we have several instances
// of the Get-<check>-Set pattern that could be optimized.

// Map is an associative mapping from keys to values.
//
// Maps can be Cloned in constant time.
// Get, Set, and Delete operations are done on average in logarithmic time.
// Maps can be merged (via SetAll) in O(m log(n/m)) time for maps of size n and m, where m < n.
//
// Values are reference counted, and a client-supplied release function
// is called when a value is no longer referenced by a map or any clone.
//
// Internally the implementation is based on a randomized persistent treap:
// https://en.wikipedia.org/wiki/Treap.
//
// The zero value is ready to use.
type Map[K constraints.Ordered, V any] struct {
	// Map is a generic wrapper around a non-generic implementation to avoid a
	// significant increase in the size of the executable.
	root *mapNode
}

func (*Map[K, V]) less(l, r any) bool {
	return l.(K) < r.(K)
}

func (m *Map[K, V]) String() string {
	var buf strings.Builder
	buf.WriteByte('{')
	var sep string
	for k, v := range m.All() {
		fmt.Fprintf(&buf, "%s%v: %v", sep, k, v)
		sep = ", "
	}
	buf.WriteByte('}')
	return buf.String()
}

type mapNode struct {
	key         any
	value       *refValue
	weight      uint64
	refCount    int32
	left, right *mapNode
}

type refValue struct {
	refCount int32
	value    any
	release  func(key, value any)
}

func newNodeWithRef[K constraints.Ordered, V any](key K, value V, release func(key, value any)) *mapNode {
	return &mapNode{
		key: key,
		value: &refValue{
			value:    value,
			release:  release,
			refCount: 1,
		},
		refCount: 1,
		weight:   rand.Uint64(),
	}
}

func (node *mapNode) shallowCloneWithRef() *mapNode {
	atomic.AddInt32(&node.value.refCount, 1)
	return &mapNode{
		key:      node.key,
		value:    node.value,
		weight:   node.weight,
		refCount: 1,
	}
}

func (node *mapNode) incref() *mapNode {
	if node != nil {
		atomic.AddInt32(&node.refCount, 1)
	}
	return node
}

func (node *mapNode) decref() {
	if node == nil {
		return
	}
	if atomic.AddInt32(&node.refCount, -1) == 0 {
		if atomic.AddInt32(&node.value.refCount, -1) == 0 {
			if node.value.release != nil {
				node.value.release(node.key, node.value.value)
			}
			node.value.value = nil
			node.value.release = nil
		}
		node.left.decref()
		node.right.decref()
	}
}

// Clone returns a copy of the given map. It is a responsibility of the caller
// to Destroy it at later time.
func (pm *Map[K, V]) Clone() *Map[K, V] {
	return &Map[K, V]{
		root: pm.root.incref(),
	}
}

// Destroy destroys the map.
//
// After Destroy, the Map should not be used again.
func (pm *Map[K, V]) Destroy() {
	// The implementation of these two functions is the same,
	// but their intent is different.
	pm.Clear()
}

// Clear removes all entries from the map.
func (pm *Map[K, V]) Clear() {
	pm.root.decref()
	pm.root = nil
}

// Keys returns the ascending sequence of keys present in the map.
func (pm *Map[K, V]) Keys() iter.Seq[K] {
	return func(yield func(K) bool) {
		pm.root.forEach(func(k, _ any) bool {
			return yield(k.(K))
		})
	}
}

// All returns the sequence of map entries in ascending key order.
func (pm *Map[K, V]) All() iter.Seq2[K, V] {
	return func(yield func(K, V) bool) {
		pm.root.forEach(func(k, v any) bool {
			return yield(k.(K), v.(V))
		})
	}
}

func (node *mapNode) forEach(yield func(key, value any) bool) bool {
	return node == nil ||
		node.left.forEach(yield) &&
			yield(node.key, node.value.value) &&
			node.right.forEach(yield)
}

// Get returns the map value associated with the specified key.
// The ok result indicates whether an entry was found in the map.
func (pm *Map[K, V]) Get(key K) (V, bool) {
	node := pm.root
	for node != nil {
		if key < node.key.(K) {
			node = node.left
		} else if node.key.(K) < key {
			node = node.right
		} else {
			return node.value.value.(V), true
		}
	}
	var zero V
	return zero, false
}

// SetAll updates the map with key/value pairs from the other map, overwriting existing keys.
// It is equivalent to calling Set for each entry in the other map but is more efficient.
func (pm *Map[K, V]) SetAll(other *Map[K, V]) {
	root := pm.root
	pm.root = union(root, other.root, pm.less, true)
	root.decref()
}

// Set updates the value associated with the specified key.
// If release is non-nil, it will be called with entry's key and value once the
// key is no longer contained in the map or any clone.
//
// TODO(adonovan): fix release, which has the wrong type.
func (pm *Map[K, V]) Set(key K, value V, release func(key, value any)) {
	first := pm.root
	second := newNodeWithRef(key, value, release)
	pm.root = union(first, second, pm.less, true)
	first.decref()
	second.decref()
}

// union returns a new tree which is a union of first and second one.
// If overwrite is set to true, second one would override a value for any duplicate keys.
//
// union(first:-0, second:-0) (result:+1)
// Union borrows both subtrees without affecting their refcount and returns a
// new reference that the caller is expected to call decref.
func union(first, second *mapNode, less func(any, any) bool, overwrite bool) *mapNode {
	if first == nil {
		return second.incref()
	}
	if second == nil {
		return first.incref()
	}

	if first.weight < second.weight {
		second, first, overwrite = first, second, !overwrite
	}

	left, mid, right := split(second, first.key, less, false)
	var result *mapNode
	if overwrite && mid != nil {
		result = mid.shallowCloneWithRef()
	} else {
		result = first.shallowCloneWithRef()
	}
	result.weight = first.weight
	result.left = union(first.left, left, less, overwrite)
	result.right = union(first.right, right, less, overwrite)
	left.decref()
	mid.decref()
	right.decref()
	return result
}

// split the tree midway by the key into three different ones.
// Return three new trees: left with all nodes with smaller than key, mid with
// the node matching the key, right with all nodes larger than key.
// If there are no nodes in one of trees, return nil instead of it.
// If requireMid is set (such as during deletion), then all return arguments
// are nil if mid is not found.
//
// split(n:-0) (left:+1, mid:+1, right:+1)
// Split borrows n without affecting its refcount, and returns three
// new references that the caller is expected to call decref.
func split(n *mapNode, key any, less func(any, any) bool, requireMid bool) (left, mid, right *mapNode) {
	if n == nil {
		return nil, nil, nil
	}

	if less(n.key, key) {
		left, mid, right := split(n.right, key, less, requireMid)
		if requireMid && mid == nil {
			return nil, nil, nil
		}
		newN := n.shallowCloneWithRef()
		newN.left = n.left.incref()
		newN.right = left
		return newN, mid, right
	} else if less(key, n.key) {
		left, mid, right := split(n.left, key, less, requireMid)
		if requireMid && mid == nil {
			return nil, nil, nil
		}
		newN := n.shallowCloneWithRef()
		newN.left = right
		newN.right = n.right.incref()
		return left, mid, newN
	}
	mid = n.shallowCloneWithRef()
	return n.left.incref(), mid, n.right.incref()
}

// Delete deletes the value for a key.
//
// The result reports whether the key was present in the map.
func (pm *Map[K, V]) Delete(key K) bool {
	root := pm.root
	left, mid, right := split(root, key, pm.less, true)
	if mid == nil {
		return false
	}
	pm.root = merge(left, right)
	left.decref()
	mid.decref()
	right.decref()
	root.decref()
	return true
}

// merge two trees while preserving the weight invariant.
// All nodes in left must have smaller keys than any node in right.
//
// merge(left:-0, right:-0) (result:+1)
// Merge borrows its arguments without affecting their refcount
// and returns a new reference that the caller is expected to call decref.
func merge(left, right *mapNode) *mapNode {
	switch {
	case left == nil:
		return right.incref()
	case right == nil:
		return left.incref()
	case left.weight > right.weight:
		root := left.shallowCloneWithRef()
		root.left = left.left.incref()
		root.right = merge(left.right, right)
		return root
	default:
		root := right.shallowCloneWithRef()
		root.left = merge(left, right.left)
		root.right = right.right.incref()
		return root
	}
}


================================================
FILE: gopls/internal/util/persistent/map_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package persistent

import (
	"fmt"
	"maps"
	"math/rand"
	"reflect"
	"sync/atomic"
	"testing"
)

type mapEntry struct {
	key   int
	value int
}

type validatedMap struct {
	impl     *Map[int, int]
	expected map[int]int      // current key-value mapping.
	deleted  map[mapEntry]int // maps deleted entries to their clock time of last deletion
	seen     map[mapEntry]int // maps seen entries to their clock time of last insertion
	clock    int
}

func TestSimpleMap(t *testing.T) {
	deletedEntries := make(map[mapEntry]int)
	seenEntries := make(map[mapEntry]int)

	m1 := &validatedMap{
		impl:     new(Map[int, int]),
		expected: make(map[int]int),
		deleted:  deletedEntries,
		seen:     seenEntries,
	}

	m3 := m1.clone()
	validateRef(t, m1, m3)
	m3.set(t, 8, 8)
	validateRef(t, m1, m3)
	m3.destroy()

	assertSameMap(t, entrySet(deletedEntries), map[mapEntry]struct{}{
		{key: 8, value: 8}: {},
	})

	validateRef(t, m1)
	m1.set(t, 1, 1)
	validateRef(t, m1)
	m1.set(t, 2, 2)
	validateRef(t, m1)
	m1.set(t, 3, 3)
	validateRef(t, m1)
	m1.remove(t, 2)
	validateRef(t, m1)
	m1.set(t, 6, 6)
	validateRef(t, m1)

	assertSameMap(t, entrySet(deletedEntries), map[mapEntry]struct{}{
		{key: 2, value: 2}: {},
		{key: 8, value: 8}: {},
	})

	m2 := m1.clone()
	validateRef(t, m1, m2)
	m1.set(t, 6, 60)
	validateRef(t, m1, m2)
	m1.remove(t, 1)
	validateRef(t, m1, m2)

	gotAllocs := int(testing.AllocsPerRun(10, func() {
		m1.impl.Delete(100)
		m1.impl.Delete(1)
	}))
	wantAllocs := 0
	if gotAllocs != wantAllocs {
		t.Errorf("wanted %d allocs, got %d", wantAllocs, gotAllocs)
	}

	for i := 10; i < 14; i++ {
		m1.set(t, i, i)
		validateRef(t, m1, m2)
	}

	m1.set(t, 10, 100)
	validateRef(t, m1, m2)

	m1.remove(t, 12)
	validateRef(t, m1, m2)

	m2.set(t, 4, 4)
	validateRef(t, m1, m2)
	m2.set(t, 5, 5)
	validateRef(t, m1, m2)

	m1.destroy()

	assertSameMap(t, entrySet(deletedEntries), map[mapEntry]struct{}{
		{key: 2, value: 2}:    {},
		{key: 6, value: 60}:   {},
		{key: 8, value: 8}:    {},
		{key: 10, value: 10}:  {},
		{key: 10, value: 100}: {},
		{key: 11, value: 11}:  {},
		{key: 12, value: 12}:  {},
		{key: 13, value: 13}:  {},
	})

	m2.set(t, 7, 7)
	validateRef(t, m2)

	m2.destroy()

	assertSameMap(t, entrySet(seenEntries), entrySet(deletedEntries))
}

func TestRandomMap(t *testing.T) {
	deletedEntries := make(map[mapEntry]int)
	seenEntries := make(map[mapEntry]int)

	m := &validatedMap{
		impl:     new(Map[int, int]),
		expected: make(map[int]int),
		deleted:  deletedEntries,
		seen:     seenEntries,
	}

	keys := make([]int, 0, 1000)
	for i := range 1000 {
		key := rand.Intn(10000)
		m.set(t, key, key)
		keys = append(keys, key)

		if i%10 == 1 {
			index := rand.Intn(len(keys))
			last := len(keys) - 1
			key = keys[index]
			keys[index], keys[last] = keys[last], keys[index]
			keys = keys[:last]

			m.remove(t, key)
		}
	}

	m.destroy()
	assertSameMap(t, entrySet(seenEntries), entrySet(deletedEntries))
}

func entrySet(m map[mapEntry]int) map[mapEntry]struct{} {
	set := make(map[mapEntry]struct{})
	for k := range m {
		set[k] = struct{}{}
	}
	return set
}

func TestUpdate(t *testing.T) {
	deletedEntries := make(map[mapEntry]int)
	seenEntries := make(map[mapEntry]int)

	m1 := &validatedMap{
		impl:     new(Map[int, int]),
		expected: make(map[int]int),
		deleted:  deletedEntries,
		seen:     seenEntries,
	}
	m2 := m1.clone()

	m1.set(t, 1, 1)
	m1.set(t, 2, 2)
	m2.set(t, 2, 20)
	m2.set(t, 3, 3)
	m1.setAll(t, m2)

	m1.destroy()
	m2.destroy()
	assertSameMap(t, entrySet(seenEntries), entrySet(deletedEntries))
}

func validateRef(t *testing.T, maps ...*validatedMap) {
	t.Helper()

	actualCountByEntry := make(map[mapEntry]int32)
	nodesByEntry := make(map[mapEntry]map[*mapNode]struct{})
	expectedCountByEntry := make(map[mapEntry]int32)
	for i, m := range maps {
		dfsRef(m.impl.root, actualCountByEntry, nodesByEntry)
		dumpMap(t, fmt.Sprintf("%d:", i), m.impl.root)
	}
	for entry, nodes := range nodesByEntry {
		expectedCountByEntry[entry] = int32(len(nodes))
	}
	assertSameMap(t, expectedCountByEntry, actualCountByEntry)
}

func dfsRef(node *mapNode, countByEntry map[mapEntry]int32, nodesByEntry map[mapEntry]map[*mapNode]struct{}) {
	if node == nil {
		return
	}

	entry := mapEntry{key: node.key.(int), value: node.value.value.(int)}
	countByEntry[entry] = atomic.LoadInt32(&node.value.refCount)

	nodes, ok := nodesByEntry[entry]
	if !ok {
		nodes = make(map[*mapNode]struct{})
		nodesByEntry[entry] = nodes
	}
	nodes[node] = struct{}{}

	dfsRef(node.left, countByEntry, nodesByEntry)
	dfsRef(node.right, countByEntry, nodesByEntry)
}

func dumpMap(t *testing.T, prefix string, n *mapNode) {
	if n == nil {
		t.Logf("%s nil", prefix)
		return
	}
	t.Logf("%s {key: %v, value: %v (ref: %v), ref: %v, weight: %v}", prefix, n.key, n.value.value, n.value.refCount, n.refCount, n.weight)
	dumpMap(t, prefix+"l", n.left)
	dumpMap(t, prefix+"r", n.right)
}

func (vm *validatedMap) validate(t *testing.T) {
	t.Helper()

	validateNode(t, vm.impl.root)

	// Note: this validation may not make sense if maps were constructed using
	// SetAll operations. If this proves to be problematic, remove the clock,
	// deleted, and seen fields.
	for key, value := range vm.expected {
		entry := mapEntry{key: key, value: value}
		if deleteAt := vm.deleted[entry]; deleteAt > vm.seen[entry] {
			t.Fatalf("entry is deleted prematurely, key: %d, value: %d", key, value)
		}
	}

	actualMap := make(map[int]int, len(vm.expected))
	for key, value := range vm.impl.All() {
		if other, ok := actualMap[key]; ok {
			t.Fatalf("key is present twice, key: %d, first value: %d, second value: %d", key, value, other)
		}
		actualMap[key] = value
	}

	assertSameMap(t, actualMap, vm.expected)
}

func validateNode(t *testing.T, node *mapNode) {
	if node == nil {
		return
	}

	if node.left != nil {
		if node.key.(int) < node.left.key.(int) {
			t.Fatalf("left child has larger key: %v vs %v", node.left.key, node.key)
		}
		if node.left.weight > node.weight {
			t.Fatalf("left child has larger weight: %v vs %v", node.left.weight, node.weight)
		}
	}

	if node.right != nil {
		if node.right.key.(int) < node.key.(int) {
			t.Fatalf("right child has smaller key: %v vs %v", node.right.key, node.key)
		}
		if node.right.weight > node.weight {
			t.Fatalf("right child has larger weight: %v vs %v", node.right.weight, node.weight)
		}
	}

	validateNode(t, node.left)
	validateNode(t, node.right)
}

func (vm *validatedMap) setAll(t *testing.T, other *validatedMap) {
	vm.impl.SetAll(other.impl)

	// Note: this is buggy because we are not updating vm.clock, vm.deleted, or
	// vm.seen.
	maps.Copy(vm.expected, other.expected)
	vm.validate(t)
}

func (vm *validatedMap) set(t *testing.T, key, value int) {
	entry := mapEntry{key: key, value: value}

	vm.clock++
	vm.seen[entry] = vm.clock

	vm.impl.Set(key, value, func(deletedKey, deletedValue any) {
		if deletedKey != key || deletedValue != value {
			t.Fatalf("unexpected passed in deleted entry: %v/%v, expected: %v/%v", deletedKey, deletedValue, key, value)
		}
		// Not safe if closure shared between two validatedMaps.
		vm.deleted[entry] = vm.clock
	})
	vm.expected[key] = value
	vm.validate(t)

	gotValue, ok := vm.impl.Get(key)
	if !ok || gotValue != value {
		t.Fatalf("unexpected get result after insertion, key: %v, expected: %v, got: %v (%v)", key, value, gotValue, ok)
	}
}

func (vm *validatedMap) remove(t *testing.T, key int) {
	vm.clock++
	deleted := vm.impl.Delete(key)
	if _, ok := vm.expected[key]; ok != deleted {
		t.Fatalf("Delete(%d) = %t, want %t", key, deleted, ok)
	}
	delete(vm.expected, key)
	vm.validate(t)

	gotValue, ok := vm.impl.Get(key)
	if ok {
		t.Fatalf("unexpected get result after removal, key: %v, got: %v", key, gotValue)
	}
}

func (vm *validatedMap) clone() *validatedMap {
	expected := make(map[int]int, len(vm.expected))
	maps.Copy(expected, vm.expected)

	return &validatedMap{
		impl:     vm.impl.Clone(),
		expected: expected,
		deleted:  vm.deleted,
		seen:     vm.seen,
	}
}

func (vm *validatedMap) destroy() {
	vm.impl.Destroy()
}

func assertSameMap(t *testing.T, map1, map2 any) {
	t.Helper()

	if !reflect.DeepEqual(map1, map2) {
		t.Fatalf("different maps:\n%v\nvs\n%v", map1, map2)
	}
}


================================================
FILE: gopls/internal/util/persistent/race_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build race

package persistent

import (
	"context"
	"maps"
	"testing"
	"time"

	"golang.org/x/sync/errgroup"
)

// TestConcurrency exercises concurrent map access.
// It doesn't assert anything, but it runs under the race detector.
func TestConcurrency(t *testing.T) {
	ctx, cancel := context.WithTimeout(t.Context(), 5*time.Second)
	defer cancel()
	var orig Map[int, int] // maps subset of [0-10] to itself (values aren't interesting)
	for i := range 10 {
		orig.Set(i, i, func(k, v any) { /* just for good measure*/ })
	}
	g, ctx := errgroup.WithContext(ctx)
	const N = 10 // concurrency level
	g.SetLimit(N)
	for range N {
		g.Go(func() error {
			// Each thread has its own clone of the original,
			// sharing internal structures. Each map is accessed
			// only by a single thread; the shared data is immutable.
			m := orig.Clone()

			// Run until the timeout.
			for ctx.Err() == nil {
				for i := range 1000 {
					key := i % 10

					switch {
					case i%2 == 0:
						_, _ = m.Get(key)
					case i%11 == 0:
						m.Set(key, key, func(key, value any) {})
					case i%13 == 0:
						_ = maps.Collect(m.All())
					case i%17 == 0:
						_ = m.Delete(key)
					case i%19 == 0:
						_ = m.Keys()
					case i%31 == 0:
						_ = m.String()
					case i%23 == 0:
						_ = m.Clone()
					}
					// Don't call m.Clear(), as it would
					// disentangle the various maps from each other.
				}
			}
			return nil
		})
	}
	g.Wait() // no errors
}


================================================
FILE: gopls/internal/util/persistent/set.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package persistent

import (
	"iter"

	"golang.org/x/tools/gopls/internal/util/constraints"
)

// Set is a collection of elements of type K.
//
// It uses immutable data structures internally, so that sets can be cloned in
// constant time.
//
// The zero value is a valid empty set.
type Set[K constraints.Ordered] struct {
	impl *Map[K, struct{}]
}

// Clone creates a copy of the receiver.
func (s *Set[K]) Clone() *Set[K] {
	clone := new(Set[K])
	if s.impl != nil {
		clone.impl = s.impl.Clone()
	}
	return clone
}

// Destroy destroys the set.
//
// After Destroy, the Set should not be used again.
func (s *Set[K]) Destroy() {
	if s.impl != nil {
		s.impl.Destroy()
	}
}

// Contains reports whether s contains the given key.
func (s *Set[K]) Contains(key K) bool {
	if s.impl == nil {
		return false
	}
	_, ok := s.impl.Get(key)
	return ok
}

// All returns the sequence of set elements in ascending order.
func (s *Set[K]) All() iter.Seq[K] {
	return func(yield func(K) bool) {
		if s.impl != nil {
			s.impl.root.forEach(func(k, _ any) bool {
				return yield(k.(K))
			})
		}
	}
}

// AddAll adds all elements from other to the receiver set.
func (s *Set[K]) AddAll(other *Set[K]) {
	if other.impl != nil {
		if s.impl == nil {
			s.impl = new(Map[K, struct{}])
		}
		s.impl.SetAll(other.impl)
	}
}

// Add adds an element to the set.
func (s *Set[K]) Add(key K) {
	if s.impl == nil {
		s.impl = new(Map[K, struct{}])
	}
	s.impl.Set(key, struct{}{}, nil)
}

// Remove removes an element from the set.
func (s *Set[K]) Remove(key K) {
	if s.impl != nil {
		s.impl.Delete(key)
	}
}


================================================
FILE: gopls/internal/util/persistent/set_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package persistent_test

import (
	"fmt"
	"strings"
	"testing"

	"golang.org/x/tools/gopls/internal/util/constraints"
	"golang.org/x/tools/gopls/internal/util/persistent"
)

func TestSet(t *testing.T) {
	const (
		add = iota
		remove
	)
	type op struct {
		op int
		v  int
	}

	tests := []struct {
		label string
		ops   []op
		want  []int
	}{
		{"empty", nil, nil},
		{"singleton", []op{{add, 1}}, []int{1}},
		{"add and remove", []op{
			{add, 1},
			{remove, 1},
		}, nil},
		{"interleaved and remove", []op{
			{add, 1},
			{add, 2},
			{remove, 1},
			{add, 3},
		}, []int{2, 3}},
	}

	for _, test := range tests {
		t.Run(test.label, func(t *testing.T) {
			var s persistent.Set[int]
			for _, op := range test.ops {
				switch op.op {
				case add:
					s.Add(op.v)
				case remove:
					s.Remove(op.v)
				}
			}

			if d := diff(&s, test.want); d != "" {
				t.Errorf("unexpected diff:\n%s", d)
			}
		})
	}
}

func TestSet_Clone(t *testing.T) {
	s1 := new(persistent.Set[int])
	s1.Add(1)
	s1.Add(2)
	s2 := s1.Clone()
	s1.Add(3)
	s2.Add(4)
	if d := diff(s1, []int{1, 2, 3}); d != "" {
		t.Errorf("s1: unexpected diff:\n%s", d)
	}
	if d := diff(s2, []int{1, 2, 4}); d != "" {
		t.Errorf("s2: unexpected diff:\n%s", d)
	}
}

func TestSet_AddAll(t *testing.T) {
	s1 := new(persistent.Set[int])
	s1.Add(1)
	s1.Add(2)
	s2 := new(persistent.Set[int])
	s2.Add(2)
	s2.Add(3)
	s2.Add(4)
	s3 := new(persistent.Set[int])

	s := new(persistent.Set[int])
	s.AddAll(s1)
	s.AddAll(s2)
	s.AddAll(s3)

	if d := diff(s1, []int{1, 2}); d != "" {
		t.Errorf("s1: unexpected diff:\n%s", d)
	}
	if d := diff(s2, []int{2, 3, 4}); d != "" {
		t.Errorf("s2: unexpected diff:\n%s", d)
	}
	if d := diff(s3, nil); d != "" {
		t.Errorf("s3: unexpected diff:\n%s", d)
	}
	if d := diff(s, []int{1, 2, 3, 4}); d != "" {
		t.Errorf("s: unexpected diff:\n%s", d)
	}
}

func diff[K constraints.Ordered](got *persistent.Set[K], want []K) string {
	wantSet := make(map[K]struct{})
	for _, w := range want {
		wantSet[w] = struct{}{}
	}
	var diff []string
	for key := range got.All() {
		if _, ok := wantSet[key]; !ok {
			diff = append(diff, fmt.Sprintf("+%v", key))
		}
	}
	for key := range wantSet {
		if !got.Contains(key) {
			diff = append(diff, fmt.Sprintf("-%v", key))
		}
	}
	if len(diff) > 0 {
		d := new(strings.Builder)
		for _, l := range diff {
			fmt.Fprintln(d, l)
		}
		return d.String()
	}
	return ""
}


================================================
FILE: gopls/internal/util/safetoken/safetoken.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package safetoken provides wrappers around methods in go/token,
// that return errors rather than panicking.
//
// It also provides a central place for workarounds in the underlying
// packages. The use of this package's functions instead of methods of
// token.File (such as Offset, Position, and PositionFor) is mandatory
// throughout the gopls codebase and enforced by a static check.
package safetoken

import (
	"fmt"
	"go/token"
)

// Offset returns f.Offset(pos), but first checks that the file
// contains the pos.
//
// The definition of "contains" here differs from that of token.File
// in order to work around a bug in the parser (issue #57490): during
// error recovery, the parser may create syntax nodes whose computed
// End position is 1 byte beyond EOF, which would cause
// token.File.Offset to panic. The workaround is that this function
// accepts a Pos that is exactly 1 byte beyond EOF and maps it to the
// EOF offset.
func Offset(f *token.File, pos token.Pos) (int, error) {
	if !inRange(f, pos) {
		// Accept a Pos that is 1 byte beyond EOF,
		// and map it to the EOF offset.
		// (Workaround for #57490.)
		if int(pos) == f.Base()+f.Size()+1 {
			return f.Size(), nil
		}

		return -1, fmt.Errorf("pos %d is not in range [%d:%d] of file %s",
			pos, f.Base(), f.Base()+f.Size(), f.Name())
	}
	return int(pos) - f.Base(), nil
}

// Offsets returns Offset(start) and Offset(end).
// It returns an error if either failed, or if start > end.
func Offsets(f *token.File, start, end token.Pos) (int, int, error) {
	startOffset, err := Offset(f, start)
	if err != nil {
		return 0, 0, fmt.Errorf("start: %v", err)
	}
	endOffset, err := Offset(f, end)
	if err != nil {
		return 0, 0, fmt.Errorf("end: %v", err)
	}
	if start > end {
		return 0, 0, fmt.Errorf("start (offset %d) > end (offset %d)", start, end)
	}
	return startOffset, endOffset, nil
}

// Pos returns f.Pos(offset), but first checks that the offset is
// non-negative and not larger than the size of the file.
func Pos(f *token.File, offset int) (token.Pos, error) {
	if !(0 <= offset && offset <= f.Size()) {
		return token.NoPos, fmt.Errorf("offset %d is not in range for file %s of size %d", offset, f.Name(), f.Size())
	}
	return token.Pos(f.Base() + offset), nil
}

// inRange reports whether file f contains position pos,
// according to the invariants of token.File.
//
// This function is not public because of the ambiguity it would
// create w.r.t. the definition of "contains". Use Offset instead.
func inRange(f *token.File, pos token.Pos) bool {
	return token.Pos(f.Base()) <= pos && pos <= token.Pos(f.Base()+f.Size())
}

// Position returns the Position for the pos value in the given file.
//
// p must be NoPos, a valid Pos in the range of f, or exactly 1 byte
// beyond the end of f. (See [Offset] for explanation.)
// Any other value causes a panic.
//
// Line directives (//line comments) are ignored.
func Position(f *token.File, pos token.Pos) token.Position {
	// Work around issue #57490.
	if int(pos) == f.Base()+f.Size()+1 {
		pos--
	}

	// TODO(adonovan): centralize the workaround for
	// golang/go#41029 (newline at EOF) here too.

	return f.PositionFor(pos, false)
}

// Line returns the line number for the given offset in the given file.
func Line(f *token.File, pos token.Pos) int {
	return Position(f, pos).Line
}

// StartPosition converts a start Pos in the FileSet into a Position.
//
// Call this function only if start represents the start of a token or
// parse tree, such as the result of Node.Pos().  If start is the end of
// an interval, such as Node.End(), call EndPosition instead, as it
// may need the correction described at [Position].
func StartPosition(fset *token.FileSet, start token.Pos) (_ token.Position) {
	if f := fset.File(start); f != nil {
		return Position(f, start)
	}
	return
}

// EndPosition converts an end Pos in the FileSet into a Position.
//
// Call this function only if pos represents the end of
// a non-empty interval, such as the result of Node.End().
func EndPosition(fset *token.FileSet, end token.Pos) (_ token.Position) {
	if f := fset.File(end); f != nil && int(end) > f.Base() {
		return Position(f, end)
	}

	// Work around issue #57490.
	if f := fset.File(end - 1); f != nil {
		return Position(f, end)
	}

	return
}


================================================
FILE: gopls/internal/util/safetoken/safetoken_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package safetoken_test

import (
	"fmt"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/gopls/internal/util/safetoken"
	"golang.org/x/tools/internal/testenv"
)

func TestWorkaroundIssue57490(t *testing.T) {
	// During error recovery the parser synthesizes various close
	// tokens at EOF, causing the End position of incomplete
	// syntax nodes, computed as Rbrace+len("}"), to be beyond EOF.
	src := `package p; func f() { var x struct`
	fset := token.NewFileSet()
	file, _ := parser.ParseFile(fset, "a.go", src, parser.SkipObjectResolution)
	tf := fset.File(file.FileStart)

	// Add another file to the FileSet.
	file2, _ := parser.ParseFile(fset, "b.go", "package q", parser.SkipObjectResolution)

	// This is the ambiguity of #57490...
	if file.End() != file2.Pos() {
		t.Errorf("file.End() %d != %d file2.Pos()", file.End(), file2.Pos())
	}
	// ...which causes these statements to panic.
	if false {
		tf.Offset(file.End())   // panic: invalid Pos value 36 (should be in [1, 35])
		tf.Position(file.End()) // panic: invalid Pos value 36 (should be in [1, 35])
	}

	// The offset of the EOF position is the file size.
	offset, err := safetoken.Offset(tf, file.End()-1)
	if err != nil || offset != tf.Size() {
		t.Errorf("Offset(EOF) = (%d, %v), want token.File.Size %d", offset, err, tf.Size())
	}

	// The offset of the file.End() position, 1 byte beyond EOF,
	// is also the size of the file.
	offset, err = safetoken.Offset(tf, file.End())
	if err != nil || offset != tf.Size() {
		t.Errorf("Offset(ast.File.End()) = (%d, %v), want token.File.Size %d", offset, err, tf.Size())
	}

	if got, want := safetoken.Position(tf, file.End()).String(), "a.go:1:35"; got != want {
		t.Errorf("Position(ast.File.End()) = %s, want %s", got, want)
	}

	if got, want := safetoken.EndPosition(fset, file.End()).String(), "a.go:1:35"; got != want {
		t.Errorf("EndPosition(ast.File.End()) = %s, want %s", got, want)
	}

	// Note that calling StartPosition on an end may yield the wrong file:
	if got, want := safetoken.StartPosition(fset, file.End()).String(), "b.go:1:1"; got != want {
		t.Errorf("StartPosition(ast.File.End()) = %s, want %s", got, want)
	}
}

// To reduce the risk of panic, or bugs for which this package
// provides a workaround, this test statically reports references to
// forbidden methods of token.File or FileSet throughout gopls and
// suggests alternatives.
func TestGoplsSourceDoesNotCallTokenFileMethods(t *testing.T) {
	testenv.NeedsGoPackages(t)
	testenv.NeedsLocalXTools(t)

	cfg := &packages.Config{
		Mode: packages.NeedName | packages.NeedModule | packages.NeedCompiledGoFiles | packages.NeedTypes | packages.NeedTypesInfo | packages.NeedSyntax | packages.NeedImports | packages.NeedDeps,
	}
	cfg.Env = os.Environ()
	cfg.Env = append(cfg.Env,
		"GOPACKAGESDRIVER=off",
		"GOWORK=off", // necessary for -mod=mod below
		"GOFLAGS=-mod=mod",
	)

	pkgs, err := packages.Load(cfg, "go/token", "golang.org/x/tools/gopls/...")
	if err != nil {
		t.Fatal(err)
	}
	var tokenPkg *packages.Package
	for _, pkg := range pkgs {
		if pkg.PkgPath == "go/token" {
			tokenPkg = pkg
			break
		}
	}
	if tokenPkg == nil {
		t.Fatal("missing package go/token")
	}

	File := tokenPkg.Types.Scope().Lookup("File")
	FileSet := tokenPkg.Types.Scope().Lookup("FileSet")

	alternative := make(map[types.Object]string)
	setAlternative := func(recv types.Object, old, new string) {
		oldMethod, _, _ := types.LookupFieldOrMethod(recv.Type(), true, recv.Pkg(), old)
		alternative[oldMethod] = new
	}
	setAlternative(File, "Line", "safetoken.Line")
	setAlternative(File, "Offset", "safetoken.Offset")
	setAlternative(File, "Position", "safetoken.Position")
	setAlternative(File, "PositionFor", "safetoken.Position")
	setAlternative(FileSet, "Position", "safetoken.StartPosition or EndPosition")
	setAlternative(FileSet, "PositionFor", "safetoken.StartPosition or EndPosition")

	for _, pkg := range pkgs {
		switch pkg.PkgPath {
		case "go/token",
			"golang.org/x/tools/gopls/internal/util/safetoken", // this package
			"golang.org/x/tools/gopls/internal/cache/parsego":  // copies go/parser/resolver.go
			continue // allow calls within these packages
		}

		for ident, obj := range pkg.TypesInfo.Uses {
			if alt, ok := alternative[obj]; ok {
				posn := safetoken.StartPosition(pkg.Fset, ident.Pos())
				fmt.Fprintf(os.Stderr, "%s: forbidden use of %v; use %s instead.\n", posn, obj, alt)
				t.Fail()
			}
		}
	}
}


================================================
FILE: gopls/internal/util/tokeninternal/tokeninternal.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// package tokeninternal provides convenient helpers for the go/token package.
package tokeninternal

import (
	"go/token"
	"slices"
)

// FileSetFor returns a new FileSet containing a sequence of new Files with
// the same base, size, and line as the input files, for use in APIs that
// require a FileSet.
//
// Precondition: the input files must be non-overlapping, and sorted in order
// of their Base.
func FileSetFor(files ...*token.File) *token.FileSet {
	fset := token.NewFileSet()
	fset.AddExistingFiles(files...)
	return fset
}

// CloneFileSet creates a new FileSet holding all files in fset. It does not
// create copies of the token.Files in fset: they are added to the resulting
// FileSet unmodified.
func CloneFileSet(fset *token.FileSet) *token.FileSet {
	return FileSetFor(slices.Collect(fset.Iterate)...)
}


================================================
FILE: gopls/internal/util/typesutil/typesutil.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesutil

import (
	"bytes"
	"go/ast"
	"go/token"
	"go/types"
	"strings"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/gopls/internal/util/bug"
)

// FormatTypeParams turns TypeParamList into its Go representation, such as:
// [T, Y]. Note that it does not print constraints as this is mainly used for
// formatting type params in method receivers.
func FormatTypeParams(tparams *types.TypeParamList) string {
	if tparams == nil || tparams.Len() == 0 {
		return ""
	}
	var buf bytes.Buffer
	buf.WriteByte('[')
	for i := 0; i < tparams.Len(); i++ {
		if i > 0 {
			buf.WriteString(", ")
		}
		buf.WriteString(tparams.At(i).Obj().Name())
	}
	buf.WriteByte(']')
	return buf.String()
}

// TypesFromContext returns the type (or perhaps zero or multiple types)
// of the "hole" into which the expression identified by path must fit.
//
// For example, given
//
//	s, i := "", 0
//	s, i = EXPR
//
// the hole that must be filled by EXPR has type (string, int).
//
// It returns nil on failure.
func TypesFromContext(info *types.Info, cur inspector.Cursor) []types.Type {
	anyType := types.Universe.Lookup("any").Type()
	var typs []types.Type

	// TODO: do cur = unparenEnclosing(cur), once CL 701035 lands.
	for cur.ParentEdgeKind() == edge.ParenExpr_X {
		cur = cur.Parent()
	}

	validType := func(t types.Type) types.Type {
		if t != nil && !containsInvalid(t) {
			return types.Default(t)
		} else {
			return anyType
		}
	}

	ek, idx := cur.ParentEdge()
	switch ek {
	case edge.AssignStmt_Lhs, edge.AssignStmt_Rhs:
		assign := cur.Parent().Node().(*ast.AssignStmt)
		// Append all lhs's type
		if len(assign.Rhs) == 1 {
			for _, lhs := range assign.Lhs {
				t := info.TypeOf(lhs)
				typs = append(typs, validType(t))
			}
			break
		}
		// Lhs and Rhs counts do not match, give up
		if len(assign.Lhs) != len(assign.Rhs) {
			break
		}
		// Append corresponding index of lhs's type
		if ek == edge.AssignStmt_Rhs {
			t := info.TypeOf(assign.Lhs[idx])
			typs = append(typs, validType(t))
		}
	case edge.ValueSpec_Names, edge.ValueSpec_Type, edge.ValueSpec_Values:
		spec := cur.Parent().Node().(*ast.ValueSpec)
		if len(spec.Values) == 1 {
			for _, lhs := range spec.Names {
				t := info.TypeOf(lhs)
				typs = append(typs, validType(t))
			}
			break
		}
		if len(spec.Values) != len(spec.Names) {
			break
		}
		t := info.TypeOf(spec.Type)
		typs = append(typs, validType(t))
	case edge.ReturnStmt_Results:
		returnstmt := cur.Parent().Node().(*ast.ReturnStmt)
		sig := EnclosingSignature(cur, info)
		if sig == nil || sig.Results() == nil {
			break
		}
		retsig := sig.Results()
		// Append all return declarations' type
		if len(returnstmt.Results) == 1 {
			for v := range retsig.Variables() {
				t := v.Type()
				typs = append(typs, validType(t))
			}
			break
		}
		// Return declaration and actual return counts do not match, give up
		if retsig.Len() != len(returnstmt.Results) {
			break
		}
		// Append corresponding index of return declaration's type
		t := retsig.At(idx).Type()
		typs = append(typs, validType(t))

	case edge.CallExpr_Args:
		call := cur.Parent().Node().(*ast.CallExpr)
		t := info.TypeOf(call.Fun)
		if t == nil {
			break
		}

		if sig, ok := t.Underlying().(*types.Signature); ok {
			var paramType types.Type
			if sig.Variadic() && idx >= sig.Params().Len()-1 {
				v := sig.Params().At(sig.Params().Len() - 1)
				if s, _ := v.Type().(*types.Slice); s != nil {
					paramType = s.Elem()
				}
			} else if idx < sig.Params().Len() {
				paramType = sig.Params().At(idx).Type()
			} else {
				break
			}
			if paramType == nil || containsInvalid(paramType) {
				paramType = anyType
			}
			typs = append(typs, paramType)
		}
	case edge.IfStmt_Cond:
		typs = append(typs, types.Typ[types.Bool])
	case edge.ForStmt_Cond:
		typs = append(typs, types.Typ[types.Bool])
	case edge.UnaryExpr_X:
		unexpr := cur.Parent().Node().(*ast.UnaryExpr)
		var t types.Type
		switch unexpr.Op {
		case token.NOT:
			t = types.Typ[types.Bool]
		case token.ADD, token.SUB, token.XOR:
			t = types.Typ[types.Int]
		default:
			t = anyType
		}
		typs = append(typs, t)
	case edge.BinaryExpr_X, edge.BinaryExpr_Y:
		binexpr := cur.Parent().Node().(*ast.BinaryExpr)
		switch ek {
		case edge.BinaryExpr_X:
			t := info.TypeOf(binexpr.Y)
			typs = append(typs, validType(t))
		case edge.BinaryExpr_Y:
			t := info.TypeOf(binexpr.X)
			typs = append(typs, validType(t))
		}
	default:
		// TODO: support other kinds of "holes" as the need arises.
	}
	return typs
}

// containsInvalid checks if the type name contains "invalid type",
// which is not a valid syntax to generate.
func containsInvalid(t types.Type) bool {
	typeString := types.TypeString(t, nil)
	return strings.Contains(typeString, types.Typ[types.Invalid].String())
}

// EnclosingSignature returns the signature of the innermost
// function enclosing the syntax node denoted by cur.
// It returns nil if the node is not within a function,
// or the function's type information is missing.
func EnclosingSignature(cur inspector.Cursor, info *types.Info) *types.Signature {
loop:
	for c := range cur.Enclosing((*ast.FuncDecl)(nil), (*ast.FuncLit)(nil)) {
		switch n := c.Node().(type) {
		case *ast.FuncDecl:
			if f, ok := info.Defs[n.Name]; ok {
				return f.Type().(*types.Signature)
			}
			bug.Reportf("FuncDecl defines no types.Func (#70666)")
			break loop
		case *ast.FuncLit:
			if f, ok := info.Types[n]; ok {
				return f.Type.(*types.Signature)
			}
			bug.Reportf("FuncLit has no type (#70666)")
			break loop
		}
	}
	return nil
}


================================================
FILE: gopls/internal/version/version.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package version manages the gopls version.
//
// The VersionOverride variable may be used to set the gopls version at link
// time.
package version

import "runtime/debug"

var VersionOverride = ""

// Version returns the gopls version.
//
// By default, this is read from runtime/debug.ReadBuildInfo, but may be
// overridden by the [VersionOverride] variable.
func Version() string {
	if VersionOverride != "" {
		return VersionOverride
	}
	if info, ok := debug.ReadBuildInfo(); ok {
		if info.Main.Version != "" {
			return info.Main.Version
		}
	}
	return "(unknown)"
}


================================================
FILE: gopls/internal/vulncheck/copier.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

//go:generate go run ./copier.go

// Copier is a tool to automate copy of govulncheck's internal files.
//
//   - copy golang.org/x/vuln/internal/osv/ to osv
//   - copy golang.org/x/vuln/internal/govulncheck/ to govulncheck
package main

import (
	"bytes"
	"encoding/json"
	"fmt"
	"go/parser"
	"go/token"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"

	"golang.org/x/tools/internal/edit"
)

func main() {
	log.SetPrefix("copier: ")
	log.SetFlags(log.Lshortfile)

	srcMod := "golang.org/x/vuln"
	srcModVers := "@latest"
	srcDir, srcVer := downloadModule(srcMod + srcModVers)

	cfg := rewrite{
		banner:        fmt.Sprintf("// Code generated by copying from %v@%v (go run copier.go); DO NOT EDIT.", srcMod, srcVer),
		srcImportPath: "golang.org/x/vuln/internal",
		dstImportPath: currentPackagePath(),
	}

	copyFiles("osv", filepath.Join(srcDir, "internal", "osv"), cfg)
	copyFiles("govulncheck", filepath.Join(srcDir, "internal", "govulncheck"), cfg)
}

type rewrite struct {
	// DO NOT EDIT marker to add at the beginning
	banner string
	// rewrite srcImportPath with dstImportPath
	srcImportPath string
	dstImportPath string
}

func copyFiles(dst, src string, cfg rewrite) {
	entries, err := os.ReadDir(src)
	if err != nil {
		log.Fatalf("failed to read dir: %v", err)
	}
	if err := os.MkdirAll(dst, 0777); err != nil {
		log.Fatalf("failed to create dir: %v", err)
	}

	for _, e := range entries {
		fname := e.Name()
		// we need only non-test go files.
		if e.IsDir() || !strings.HasSuffix(fname, ".go") || strings.HasSuffix(fname, "_test.go") {
			continue
		}
		data, err := os.ReadFile(filepath.Join(src, fname))
		if err != nil {
			log.Fatal(err)
		}
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, fname, data, parser.ParseComments|parser.ImportsOnly)
		if err != nil {
			log.Fatalf("parsing source module:\n%s", err)
		}

		buf := edit.NewBuffer(data)
		at := func(p token.Pos) int {
			return fset.File(p).Offset(p)
		}

		// Add banner right after the copyright statement (the first comment)
		bannerInsert, banner := f.FileStart, cfg.banner
		if len(f.Comments) > 0 && strings.HasPrefix(f.Comments[0].Text(), "Copyright ") {
			bannerInsert = f.Comments[0].End()
			banner = "\n\n" + banner
		}
		buf.Replace(at(bannerInsert), at(bannerInsert), banner)

		// Adjust imports
		for _, spec := range f.Imports {
			path, err := strconv.Unquote(spec.Path.Value)
			if err != nil {
				log.Fatal(err)
			}
			if strings.HasPrefix(path, cfg.srcImportPath) {
				newPath := strings.Replace(path, cfg.srcImportPath, cfg.dstImportPath, 1)
				buf.Replace(at(spec.Path.Pos()), at(spec.Path.End()), strconv.Quote(newPath))
			}
		}
		data = buf.Bytes()

		if err := os.WriteFile(filepath.Join(dst, fname), data, 0666); err != nil {
			log.Fatal(err)
		}
	}
}

func downloadModule(srcModVers string) (dir, ver string) {
	var stdout, stderr bytes.Buffer
	cmd := exec.Command("go", "mod", "download", "-json", srcModVers)
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		log.Fatalf("go mod download -json %s: %v\n%s%s", srcModVers, err, stderr.Bytes(), stdout.Bytes())
	}
	var info struct {
		Dir     string
		Version string
	}
	if err := json.Unmarshal(stdout.Bytes(), &info); err != nil {
		log.Fatalf("go mod download -json %s: invalid JSON output: %v\n%s%s", srcModVers, err, stderr.Bytes(), stdout.Bytes())
	}
	return info.Dir, info.Version
}

func currentPackagePath() string {
	var stdout, stderr bytes.Buffer
	cmd := exec.Command("go", "list", ".")
	cmd.Stdout = &stdout
	cmd.Stderr = &stderr
	if err := cmd.Run(); err != nil {
		log.Fatalf("go list: %v\n%s%s", err, stderr.Bytes(), stdout.Bytes())
	}
	return strings.TrimSpace(stdout.String())
}


================================================
FILE: gopls/internal/vulncheck/govulncheck/govulncheck.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copying from golang.org/x/vuln@v1.0.1 (go run copier.go); DO NOT EDIT.

// Package govulncheck contains the JSON output structs for govulncheck.
package govulncheck

import (
	"time"

	"golang.org/x/tools/gopls/internal/vulncheck/osv"
)

const (
	// ProtocolVersion is the current protocol version this file implements
	ProtocolVersion = "v1.0.0"
)

// Message is an entry in the output stream. It will always have exactly one
// field filled in.
type Message struct {
	Config   *Config    `json:"config,omitempty"`
	Progress *Progress  `json:"progress,omitempty"`
	OSV      *osv.Entry `json:"osv,omitempty"`
	Finding  *Finding   `json:"finding,omitempty"`
}

// Config must occur as the first message of a stream and informs the client
// about the information used to generate the findings.
// The only required field is the protocol version.
type Config struct {
	// ProtocolVersion specifies the version of the JSON protocol.
	ProtocolVersion string `json:"protocol_version"`

	// ScannerName is the name of the tool, for example, govulncheck.
	//
	// We expect this JSON format to be used by other tools that wrap
	// govulncheck, which will have a different name.
	ScannerName string `json:"scanner_name,omitempty"`

	// ScannerVersion is the version of the tool.
	ScannerVersion string `json:"scanner_version,omitempty"`

	// DB is the database used by the tool, for example,
	// vuln.go.dev.
	DB string `json:"db,omitempty"`

	// LastModified is the last modified time of the data source.
	DBLastModified *time.Time `json:"db_last_modified,omitempty"`

	// GoVersion is the version of Go used for analyzing standard library
	// vulnerabilities.
	GoVersion string `json:"go_version,omitempty"`

	// ScanLevel instructs govulncheck to analyze at a specific level of detail.
	// Valid values include module, package and symbol.
	ScanLevel ScanLevel `json:"scan_level,omitempty"`
}

// Progress messages are informational only, intended to allow users to monitor
// the progress of a long running scan.
// A stream must remain fully valid and able to be interpreted with all progress
// messages removed.
type Progress struct {
	// A time stamp for the message.
	Timestamp *time.Time `json:"time,omitempty"`

	// Message is the progress message.
	Message string `json:"message,omitempty"`
}

// Vuln represents a single OSV entry.
type Finding struct {
	// OSV is the id of the detected vulnerability.
	OSV string `json:"osv,omitempty"`

	// FixedVersion is the module version where the vulnerability was
	// fixed. This is empty if a fix is not available.
	//
	// If there are multiple fixed versions in the OSV report, this will
	// be the fixed version in the latest range event for the OSV report.
	//
	// For example, if the range events are
	// {introduced: 0, fixed: 1.0.0} and {introduced: 1.1.0}, the fixed version
	// will be empty.
	//
	// For the stdlib, we will show the fixed version closest to the
	// Go version that is used. For example, if a fix is available in 1.17.5 and
	// 1.18.5, and the GOVERSION is 1.17.3, 1.17.5 will be returned as the
	// fixed version.
	FixedVersion string `json:"fixed_version,omitempty"`

	// Trace contains an entry for each frame in the trace.
	//
	// Frames are sorted starting from the imported vulnerable symbol
	// until the entry point. The first frame in Frames should match
	// Symbol.
	//
	// In binary mode, trace will contain a single-frame with no position
	// information.
	//
	// When a package is imported but no vulnerable symbol is called, the trace
	// will contain a single-frame with no symbol or position information.
	Trace []*Frame `json:"trace,omitempty"`
}

// Frame represents an entry in a finding trace.
type Frame struct {
	// Module is the module path of the module containing this symbol.
	//
	// Importable packages in the standard library will have the path "stdlib".
	Module string `json:"module"`

	// Version is the module version from the build graph.
	Version string `json:"version,omitempty"`

	// Package is the import path.
	Package string `json:"package,omitempty"`

	// Function is the function name.
	Function string `json:"function,omitempty"`

	// Receiver is the receiver type if the called symbol is a method.
	//
	// The client can create the final symbol name by
	// prepending Receiver to FuncName.
	Receiver string `json:"receiver,omitempty"`

	// Position describes an arbitrary source position
	// including the file, line, and column location.
	// A Position is valid if the line number is > 0.
	Position *Position `json:"position,omitempty"`
}

// Position represents arbitrary source position.
type Position struct {
	Filename string `json:"filename,omitempty"` // filename, if any
	Offset   int    `json:"offset"`             // byte offset, starting at 0
	Line     int    `json:"line"`               // line number, starting at 1
	Column   int    `json:"column"`             // column number, starting at 1 (byte count)
}

// ScanLevel represents the detail level at which a scan occurred.
// This can be necessary to correctly interpret the findings, for instance if
// a scan is at symbol level and a finding does not have a symbol it means the
// vulnerability was imported but not called. If the scan however was at
// "package" level, that determination cannot be made.
type ScanLevel string

const (
	scanLevelModule  = "module"
	scanLevelPackage = "package"
	scanLevelSymbol  = "symbol"
)

// WantSymbols can be used to check whether the scan level is one that is able
// to generate symbols called findings.
func (l ScanLevel) WantSymbols() bool { return l == scanLevelSymbol }


================================================
FILE: gopls/internal/vulncheck/govulncheck/handler.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copying from golang.org/x/vuln@v1.0.1 (go run copier.go); DO NOT EDIT.

package govulncheck

import (
	"encoding/json"
	"io"

	"golang.org/x/tools/gopls/internal/vulncheck/osv"
)

// Handler handles messages to be presented in a vulnerability scan output
// stream.
type Handler interface {
	// Config communicates introductory message to the user.
	Config(config *Config) error

	// Progress is called to display a progress message.
	Progress(progress *Progress) error

	// OSV is invoked for each osv Entry in the stream.
	OSV(entry *osv.Entry) error

	// Finding is called for each vulnerability finding in the stream.
	Finding(finding *Finding) error
}

// HandleJSON reads the json from the supplied stream and hands the decoded
// output to the handler.
func HandleJSON(from io.Reader, to Handler) error {
	dec := json.NewDecoder(from)
	for dec.More() {
		msg := Message{}
		// decode the next message in the stream
		if err := dec.Decode(&msg); err != nil {
			return err
		}
		// dispatch the message
		var err error
		if msg.Config != nil {
			err = to.Config(msg.Config)
		}
		if msg.Progress != nil {
			err = to.Progress(msg.Progress)
		}
		if msg.OSV != nil {
			err = to.OSV(msg.OSV)
		}
		if msg.Finding != nil {
			err = to.Finding(msg.Finding)
		}
		if err != nil {
			return err
		}
	}
	return nil
}


================================================
FILE: gopls/internal/vulncheck/govulncheck/jsonhandler.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copying from golang.org/x/vuln@v1.0.1 (go run copier.go); DO NOT EDIT.

package govulncheck

import (
	"encoding/json"

	"io"

	"golang.org/x/tools/gopls/internal/vulncheck/osv"
)

type jsonHandler struct {
	enc *json.Encoder
}

// NewJSONHandler returns a handler that writes govulncheck output as json.
func NewJSONHandler(w io.Writer) Handler {
	enc := json.NewEncoder(w)
	enc.SetIndent("", "  ")
	return &jsonHandler{enc: enc}
}

// Config writes config block in JSON to the underlying writer.
func (h *jsonHandler) Config(config *Config) error {
	return h.enc.Encode(Message{Config: config})
}

// Progress writes a progress message in JSON to the underlying writer.
func (h *jsonHandler) Progress(progress *Progress) error {
	return h.enc.Encode(Message{Progress: progress})
}

// OSV writes an osv entry in JSON to the underlying writer.
func (h *jsonHandler) OSV(entry *osv.Entry) error {
	return h.enc.Encode(Message{OSV: entry})
}

// Finding writes a finding in JSON to the underlying writer.
func (h *jsonHandler) Finding(finding *Finding) error {
	return h.enc.Encode(Message{Finding: finding})
}


================================================
FILE: gopls/internal/vulncheck/osv/osv.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copying from golang.org/x/vuln@v1.0.1 (go run copier.go); DO NOT EDIT.

// Package osv implements the Go OSV vulnerability format
// (https://go.dev/security/vuln/database#schema), which is a subset of
// the OSV shared vulnerability format
// (https://ossf.github.io/osv-schema), with database and
// ecosystem-specific meanings and fields.
//
// As this package is intended for use with the Go vulnerability
// database, only the subset of features which are used by that
// database are implemented (for instance, only the SEMVER affected
// range type is implemented).
package osv

import "time"

// RangeType specifies the type of version range being recorded and
// defines the interpretation of the RangeEvent object's Introduced
// and Fixed fields.
//
// In this implementation, only the "SEMVER" type is supported.
//
// See https://ossf.github.io/osv-schema/#affectedrangestype-field.
type RangeType string

// RangeTypeSemver indicates a semantic version as defined by
// SemVer 2.0.0, with no leading "v" prefix.
const RangeTypeSemver RangeType = "SEMVER"

// Ecosystem identifies the overall library ecosystem.
// In this implementation, only the "Go" ecosystem is supported.
type Ecosystem string

// GoEcosystem indicates the Go ecosystem.
const GoEcosystem Ecosystem = "Go"

// Pseudo-module paths used to describe vulnerabilities
// in the Go standard library and toolchain.
const (
	// GoStdModulePath is the pseudo-module path string used
	// to describe vulnerabilities in the Go standard library.
	GoStdModulePath = "stdlib"
	// GoCmdModulePath is the pseudo-module path string used
	// to describe vulnerabilities in the go command.
	GoCmdModulePath = "toolchain"
)

// Module identifies the Go module containing the vulnerability.
// Note that this field is called "package" in the OSV specification.
//
// See https://ossf.github.io/osv-schema/#affectedpackage-field.
type Module struct {
	// The Go module path. Required.
	// For the Go standard library, this is "stdlib".
	// For the Go toolchain, this is "toolchain."
	Path string `json:"name"`
	// The ecosystem containing the module. Required.
	// This should always be "Go".
	Ecosystem Ecosystem `json:"ecosystem"`
}

// RangeEvent describes a single module version that either
// introduces or fixes a vulnerability.
//
// Exactly one of Introduced and Fixed must be present. Other range
// event types (e.g, "last_affected" and "limit") are not supported in
// this implementation.
//
// See https://ossf.github.io/osv-schema/#affectedrangesevents-fields.
type RangeEvent struct {
	// Introduced is a version that introduces the vulnerability.
	// A special value, "0", represents a version that sorts before
	// any other version, and should be used to indicate that the
	// vulnerability exists from the "beginning of time".
	Introduced string `json:"introduced,omitempty"`
	// Fixed is a version that fixes the vulnerability.
	Fixed string `json:"fixed,omitempty"`
}

// Range describes the affected versions of the vulnerable module.
//
// See https://ossf.github.io/osv-schema/#affectedranges-field.
type Range struct {
	// Type is the version type that should be used to interpret the
	// versions in Events. Required.
	// In this implementation, only the "SEMVER" type is supported.
	Type RangeType `json:"type"`
	// Events is a list of versions representing the ranges in which
	// the module is vulnerable. Required.
	// The events should be sorted, and MUST represent non-overlapping
	// ranges.
	// There must be at least one RangeEvent containing a value for
	// Introduced.
	// See https://ossf.github.io/osv-schema/#examples for examples.
	Events []RangeEvent `json:"events"`
}

// Reference type is a reference (link) type.
type ReferenceType string

const (
	// ReferenceTypeAdvisory is a published security advisory for
	// the vulnerability.
	ReferenceTypeAdvisory = ReferenceType("ADVISORY")
	// ReferenceTypeArticle is an article or blog post describing the vulnerability.
	ReferenceTypeArticle = ReferenceType("ARTICLE")
	// ReferenceTypeReport is a report, typically on a bug or issue tracker, of
	// the vulnerability.
	ReferenceTypeReport = ReferenceType("REPORT")
	// ReferenceTypeFix is a source code browser link to the fix (e.g., a GitHub commit).
	ReferenceTypeFix = ReferenceType("FIX")
	// ReferenceTypePackage is a home web page for the package.
	ReferenceTypePackage = ReferenceType("PACKAGE")
	// ReferenceTypeEvidence is a demonstration of the validity of a vulnerability claim.
	ReferenceTypeEvidence = ReferenceType("EVIDENCE")
	// ReferenceTypeWeb is a web page of some unspecified kind.
	ReferenceTypeWeb = ReferenceType("WEB")
)

// Reference is a reference URL containing additional information,
// advisories, issue tracker entries, etc., about the vulnerability.
//
// See https://ossf.github.io/osv-schema/#references-field.
type Reference struct {
	// The type of reference. Required.
	Type ReferenceType `json:"type"`
	// The fully-qualified URL of the reference. Required.
	URL string `json:"url"`
}

// Affected gives details about a module affected by the vulnerability.
//
// See https://ossf.github.io/osv-schema/#affected-fields.
type Affected struct {
	// The affected Go module. Required.
	// Note that this field is called "package" in the OSV specification.
	Module Module `json:"package"`
	// The module version ranges affected by the vulnerability.
	Ranges []Range `json:"ranges,omitempty"`
	// Details on the affected packages and symbols within the module.
	EcosystemSpecific EcosystemSpecific `json:"ecosystem_specific"`
}

// Package contains additional information about an affected package.
// This is an ecosystem-specific field for the Go ecosystem.
type Package struct {
	// Path is the package import path. Required.
	Path string `json:"path,omitempty"`
	// GOOS is the execution operating system where the symbols appear, if
	// known.
	GOOS []string `json:"goos,omitempty"`
	// GOARCH specifies the execution architecture where the symbols appear, if
	// known.
	GOARCH []string `json:"goarch,omitempty"`
	// Symbols is a list of function and method names affected by
	// this vulnerability. Methods are listed as <recv>.<method>.
	//
	// If included, only programs which use these symbols will be marked as
	// vulnerable by `govulncheck`. If omitted, any program which imports this
	// package will be marked vulnerable.
	Symbols []string `json:"symbols,omitempty"`
}

// EcosystemSpecific contains additional information about the vulnerable
// module for the Go ecosystem.
//
// See https://go.dev/security/vuln/database#schema.
type EcosystemSpecific struct {
	// Packages is the list of affected packages within the module.
	Packages []Package `json:"imports,omitempty"`
}

// Entry represents a vulnerability in the Go OSV format, documented
// in https://go.dev/security/vuln/database#schema.
// It is a subset of the OSV schema (https://ossf.github.io/osv-schema).
// Only fields that are published in the Go Vulnerability Database
// are supported.
type Entry struct {
	// SchemaVersion is the OSV schema version used to encode this
	// vulnerability.
	SchemaVersion string `json:"schema_version,omitempty"`
	// ID is a unique identifier for the vulnerability. Required.
	// The Go vulnerability database issues IDs of the form
	// GO-<YEAR>-<ENTRYID>.
	ID string `json:"id"`
	// Modified is the time the entry was last modified. Required.
	Modified time.Time `json:"modified,omitempty"`
	// Published is the time the entry should be considered to have
	// been published.
	Published time.Time `json:"published,omitempty"`
	// Withdrawn is the time the entry should be considered to have
	// been withdrawn. If the field is missing, then the entry has
	// not been withdrawn.
	Withdrawn *time.Time `json:"withdrawn,omitempty"`
	// Aliases is a list of IDs for the same vulnerability in other
	// databases.
	Aliases []string `json:"aliases,omitempty"`
	// Summary gives a one-line, English textual summary of the vulnerability.
	// It is recommended that this field be kept short, on the order of no more
	// than 120 characters.
	Summary string `json:"summary,omitempty"`
	// Details contains additional English textual details about the vulnerability.
	Details string `json:"details"`
	// Affected contains information on the modules and versions
	// affected by the vulnerability.
	Affected []Affected `json:"affected"`
	// References contains links to more information about the
	// vulnerability.
	References []Reference `json:"references,omitempty"`
	// Credits contains credits to entities that helped find or fix the
	// vulnerability.
	Credits []Credit `json:"credits,omitempty"`
	// DatabaseSpecific contains additional information about the
	// vulnerability, specific to the Go vulnerability database.
	DatabaseSpecific *DatabaseSpecific `json:"database_specific,omitempty"`
}

// Credit represents a credit for the discovery, confirmation, patch, or
// other event in the life cycle of a vulnerability.
//
// See https://ossf.github.io/osv-schema/#credits-fields.
type Credit struct {
	// Name is the name, label, or other identifier of the individual or
	// entity being credited. Required.
	Name string `json:"name"`
}

// DatabaseSpecific contains additional information about the
// vulnerability, specific to the Go vulnerability database.
//
// See https://go.dev/security/vuln/database#schema.
type DatabaseSpecific struct {
	// The URL of the Go advisory for this vulnerability, of the form
	// "https://pkg.go.dev/GO-YYYY-XXXX".
	URL string `json:"url,omitempty"`
}


================================================
FILE: gopls/internal/vulncheck/scan/command.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package scan

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"os"
	"os/exec"
	"sort"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/vulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
	"golang.org/x/vuln/scan"
)

// Main implements gopls vulncheck.
func Main(ctx context.Context, args ...string) error {
	// wrapping govulncheck.
	cmd := scan.Command(ctx, args...)
	if err := cmd.Start(); err != nil {
		return err
	}
	return cmd.Wait()
}

// RunGovulncheck implements the codelens "Run Govulncheck"
// that runs 'gopls vulncheck' and converts the output to gopls's internal data
// used for diagnostics and hover message construction.
//
// TODO(rfindley): this should accept a *View (which exposes) Options, rather
// than a snapshot.
func RunGovulncheck(ctx context.Context, pattern string, snapshot *cache.Snapshot, dir string, log io.Writer) (*vulncheck.Result, error) {
	vulncheckargs := []string{
		"vulncheck", "--",
		"-json",
		"-mode", "source",
		"-scan", "symbol",
	}
	if dir != "" {
		vulncheckargs = append(vulncheckargs, "-C", dir)
	}
	if db := cache.GetEnv(snapshot, "GOVULNDB"); db != "" {
		vulncheckargs = append(vulncheckargs, "-db", db)
	}
	vulncheckargs = append(vulncheckargs, pattern)
	// TODO: support -tags. need to compute tags args from opts.BuildFlags.
	// TODO: support -test.

	ir, iw := io.Pipe()
	handler := &govulncheckHandler{logger: log, osvs: map[string]*osv.Entry{}}

	stderr := new(bytes.Buffer)
	var g errgroup.Group
	// We run the govulncheck's analysis in a separate process as it can
	// consume a lot of CPUs and memory, and terminates: a separate process
	// is a perfect garbage collector and affords us ways to limit its resource usage.
	g.Go(func() error {
		defer iw.Close()

		cmd := exec.CommandContext(ctx, os.Args[0], vulncheckargs...)
		cmd.Env = getEnvSlices(snapshot)
		if goversion := cache.GetEnv(snapshot, cache.GoVersionForVulnTest); goversion != "" {
			// Let govulncheck API use a different Go version using the (undocumented) hook
			// in https://go.googlesource.com/vuln/+/v1.0.1/internal/scan/run.go#76
			cmd.Env = append(cmd.Env, "GOVERSION="+goversion)
		}
		cmd.Stderr = stderr // stream vulncheck's STDERR as progress reports
		cmd.Stdout = iw     // let the other goroutine parses the result.

		if err := cmd.Start(); err != nil {
			return fmt.Errorf("failed to start govulncheck: %v", err)
		}
		if err := cmd.Wait(); err != nil {
			return fmt.Errorf("failed to run govulncheck: %v", err)
		}
		return nil
	})
	g.Go(func() error {
		return govulncheck.HandleJSON(ir, handler)
	})
	if err := g.Wait(); err != nil {
		if stderr.Len() > 0 {
			log.Write(stderr.Bytes())
		}
		return nil, fmt.Errorf("failed to read govulncheck output: %v: stderr:\n%s", err, stderr)
	}

	findings := handler.findings // sort so the findings in the result is deterministic.
	sort.Slice(findings, func(i, j int) bool {
		x, y := findings[i], findings[j]
		if x.OSV != y.OSV {
			return x.OSV < y.OSV
		}
		return x.Trace[0].Package < y.Trace[0].Package
	})
	result := &vulncheck.Result{
		Mode:     vulncheck.ModeGovulncheck,
		AsOf:     time.Now(),
		Entries:  handler.osvs,
		Findings: findings,
	}
	return result, nil
}

type govulncheckHandler struct {
	logger io.Writer // forward progress reports to logger.

	osvs     map[string]*osv.Entry
	findings []*govulncheck.Finding
}

// Config implements vulncheck.Handler.
func (h *govulncheckHandler) Config(config *govulncheck.Config) error {
	if config.GoVersion != "" {
		fmt.Fprintf(h.logger, "Go: %v\n", config.GoVersion)
	}
	if config.ScannerName != "" {
		scannerName := fmt.Sprintf("Scanner: %v", config.ScannerName)
		if config.ScannerVersion != "" {
			scannerName += "@" + config.ScannerVersion
		}
		fmt.Fprintln(h.logger, scannerName)
	}
	if config.DB != "" {
		dbInfo := fmt.Sprintf("DB: %v", config.DB)
		if config.DBLastModified != nil {
			dbInfo += fmt.Sprintf(" (DB updated: %v)", config.DBLastModified.String())
		}
		fmt.Fprintln(h.logger, dbInfo)
	}
	return nil
}

// Finding implements vulncheck.Handler.
func (h *govulncheckHandler) Finding(finding *govulncheck.Finding) error {
	h.findings = append(h.findings, finding)
	return nil
}

// OSV implements vulncheck.Handler.
func (h *govulncheckHandler) OSV(entry *osv.Entry) error {
	h.osvs[entry.ID] = entry
	return nil
}

// Progress implements vulncheck.Handler.
func (h *govulncheckHandler) Progress(progress *govulncheck.Progress) error {
	if progress.Message != "" {
		fmt.Fprintf(h.logger, "%v\n", progress.Message)
	}
	return nil
}

func getEnvSlices(snapshot *cache.Snapshot) []string {
	return append(os.Environ(), snapshot.Options().EnvSlice()...)
}


================================================
FILE: gopls/internal/vulncheck/semver/semver.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package semver provides shared utilities for manipulating
// Go semantic versions.
package semver

import (
	"strings"

	"golang.org/x/mod/semver"
)

// addSemverPrefix adds a 'v' prefix to s if it isn't already prefixed
// with 'v' or 'go'. This allows us to easily test go-style SEMVER
// strings against normal SEMVER strings.
func addSemverPrefix(s string) string {
	if !strings.HasPrefix(s, "v") && !strings.HasPrefix(s, "go") {
		return "v" + s
	}
	return s
}

// removeSemverPrefix removes the 'v' or 'go' prefixes from go-style
// SEMVER strings, for usage in the public vulnerability format.
func removeSemverPrefix(s string) string {
	s = strings.TrimPrefix(s, "v")
	s = strings.TrimPrefix(s, "go")
	return s
}

// CanonicalizeSemverPrefix turns a SEMVER string into the canonical
// representation using the 'v' prefix, as used by the OSV format.
// Input may be a bare SEMVER ("1.2.3"), Go prefixed SEMVER ("go1.2.3"),
// or already canonical SEMVER ("v1.2.3").
func CanonicalizeSemverPrefix(s string) string {
	return addSemverPrefix(removeSemverPrefix(s))
}

// Valid returns whether v is valid semver, allowing
// either a "v", "go" or no prefix.
func Valid(v string) bool {
	return semver.IsValid(CanonicalizeSemverPrefix(v))
}


================================================
FILE: gopls/internal/vulncheck/semver/semver_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package semver

import (
	"testing"
)

func TestCanonicalize(t *testing.T) {
	for _, test := range []struct {
		v    string
		want string
	}{
		{"v1.2.3", "v1.2.3"},
		{"1.2.3", "v1.2.3"},
		{"go1.2.3", "v1.2.3"},
	} {
		got := CanonicalizeSemverPrefix(test.v)
		if got != test.want {
			t.Errorf("want %s; got %s", test.want, got)
		}
	}
}


================================================
FILE: gopls/internal/vulncheck/types.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// go:generate go run copier.go

package vulncheck

import (
	"time"

	gvc "golang.org/x/tools/gopls/internal/vulncheck/govulncheck"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
)

// Result is the result of vulnerability scanning.
type Result struct {
	// Entries contains all vulnerabilities that are called or imported by
	// the analyzed module. Keys are Entry.IDs.
	Entries map[string]*osv.Entry
	// Findings are vulnerabilities found by vulncheck or import-based analysis.
	// Ordered by the OSV IDs and the package names.
	Findings []*gvc.Finding

	// Mode contains the source of the vulnerability info.
	// Clients of the gopls.fetch_vulncheck_result command may need
	// to interpret the vulnerabilities differently based on the
	// analysis mode. For example, Vuln without callstack traces
	// indicate a vulnerability that is not used if the result was
	// from 'govulncheck' analysis mode. On the other hand, Vuln
	// without callstack traces just implies the package with the
	// vulnerability is known to the workspace and we do not know
	// whether the vulnerable symbols are actually used or not.
	Mode AnalysisMode `json:",omitempty"`

	// AsOf describes when this Result was computed using govulncheck.
	// It is valid only with the govulncheck analysis mode.
	AsOf time.Time
}

type AnalysisMode string

const (
	ModeInvalid     AnalysisMode = "" // zero value
	ModeGovulncheck AnalysisMode = "govulncheck"
	ModeImports     AnalysisMode = "imports"
)


================================================
FILE: gopls/internal/vulncheck/vulntest/db.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package vulntest provides helpers for vulncheck functionality testing.
package vulntest

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"slices"
	"sort"
	"strings"
	"time"

	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
	"golang.org/x/tools/txtar"
)

// NewDatabase returns a read-only DB containing the provided
// txtar-format collection of vulnerability reports.
// Each vulnerability report is a YAML file whose format
// is defined in golang.org/x/vulndb/doc/format.md.
// A report file name must have the id as its base name,
// and have .yaml as its extension.
//
//	db, err := NewDatabase(ctx, reports)
//	...
//	defer db.Clean()
//	client, err := NewClient(db)
//	...
//
// The returned DB's Clean method must be called to clean up the
// generated database.
func NewDatabase(ctx context.Context, txtarReports []byte) (*DB, error) {
	disk, err := os.MkdirTemp("", "vulndb-test")
	if err != nil {
		return nil, err
	}
	if err := generateDB(ctx, txtarReports, disk, false); err != nil {
		os.RemoveAll(disk) // ignore error
		return nil, err
	}

	return &DB{disk: disk}, nil
}

// DB is a read-only vulnerability database on disk.
// Users can use this database with golang.org/x/vuln APIs
// by setting the `VULNDB` environment variable.
type DB struct {
	disk string
}

// URI returns the file URI that can be used for VULNDB environment
// variable.
func (db *DB) URI() string {
	u := protocol.URIFromPath(filepath.Join(db.disk, "ID"))
	return string(u)
}

// Clean deletes the database.
func (db *DB) Clean() error {
	return os.RemoveAll(db.disk)
}

//
// The following was selectively copied from golang.org/x/vulndb/internal/database
//

const (
	dbURL = "https://pkg.go.dev/vuln/"

	// idDirectory is the name of the directory that contains entries
	// listed by their IDs.
	idDirectory = "ID"

	// cmdModule is the name of the module containing Go toolchain
	// binaries.
	cmdModule = "cmd"

	// stdModule is the name of the module containing Go std packages.
	stdModule = "std"
)

// generateDB generates the file-based vuln DB in the directory jsonDir.
func generateDB(ctx context.Context, txtarData []byte, jsonDir string, indent bool) error {
	archive := txtar.Parse(txtarData)

	entries, err := generateEntries(ctx, archive)
	if err != nil {
		return err
	}
	return writeEntriesByID(filepath.Join(jsonDir, idDirectory), entries, indent)
}

func generateEntries(_ context.Context, archive *txtar.Archive) ([]osv.Entry, error) {
	now := time.Now()
	var entries []osv.Entry
	for _, f := range archive.Files {
		if !strings.HasSuffix(f.Name, ".yaml") {
			continue
		}
		r, err := readReport(bytes.NewReader(f.Data))
		if err != nil {
			return nil, err
		}
		name := strings.TrimSuffix(filepath.Base(f.Name), filepath.Ext(f.Name))
		linkName := fmt.Sprintf("%s%s", dbURL, name)
		entry := generateOSVEntry(name, linkName, now, *r)
		entries = append(entries, entry)
	}
	return entries, nil
}

func writeEntriesByID(idDir string, entries []osv.Entry, indent bool) error {
	// Write a directory containing entries by ID.
	if err := os.MkdirAll(idDir, 0755); err != nil {
		return fmt.Errorf("failed to create directory %q: %v", idDir, err)
	}
	for _, e := range entries {
		outPath := filepath.Join(idDir, e.ID+".json")
		if err := writeJSON(outPath, e, indent); err != nil {
			return err
		}
	}
	return nil
}

func writeJSON(filename string, value any, indent bool) (err error) {
	j, err := jsonMarshal(value, indent)
	if err != nil {
		return err
	}
	return os.WriteFile(filename, j, 0644)
}

func jsonMarshal(v any, indent bool) ([]byte, error) {
	if indent {
		return json.MarshalIndent(v, "", "  ")
	}
	return json.Marshal(v)
}

// generateOSVEntry create an osv.Entry for a report. In addition to the report, it
// takes the ID for the vuln and a URL that will point to the entry in the vuln DB.
// It returns the osv.Entry and a list of module paths that the vuln affects.
func generateOSVEntry(id, url string, lastModified time.Time, r Report) osv.Entry {
	entry := osv.Entry{
		ID:               id,
		Published:        r.Published,
		Modified:         lastModified,
		Withdrawn:        r.Withdrawn,
		Summary:          r.Summary,
		Details:          r.Description,
		DatabaseSpecific: &osv.DatabaseSpecific{URL: url},
	}

	moduleMap := make(map[string]bool)
	for _, m := range r.Modules {
		switch m.Module {
		case stdModule:
			moduleMap[osv.GoStdModulePath] = true
		case cmdModule:
			moduleMap[osv.GoCmdModulePath] = true
		default:
			moduleMap[m.Module] = true
		}
		entry.Affected = append(entry.Affected, toAffected(m))
	}
	for _, ref := range r.References {
		entry.References = append(entry.References, osv.Reference{
			Type: ref.Type,
			URL:  ref.URL,
		})
	}
	return entry
}

func AffectedRanges(versions []VersionRange) []osv.Range {
	a := osv.Range{Type: osv.RangeTypeSemver}
	if len(versions) == 0 || versions[0].Introduced == "" {
		a.Events = append(a.Events, osv.RangeEvent{Introduced: "0"})
	}
	for _, v := range versions {
		if v.Introduced != "" {
			a.Events = append(a.Events, osv.RangeEvent{Introduced: v.Introduced.Canonical()})
		}
		if v.Fixed != "" {
			a.Events = append(a.Events, osv.RangeEvent{Fixed: v.Fixed.Canonical()})
		}
	}
	return []osv.Range{a}
}

func toOSVPackages(pkgs []*Package) (imps []osv.Package) {
	for _, p := range pkgs {
		syms := slices.Clone(p.Symbols)
		syms = append(syms, p.DerivedSymbols...)
		sort.Strings(syms)
		imps = append(imps, osv.Package{
			Path:    p.Package,
			GOOS:    p.GOOS,
			GOARCH:  p.GOARCH,
			Symbols: syms,
		})
	}
	return imps
}

func toAffected(m *Module) osv.Affected {
	name := m.Module
	switch name {
	case stdModule:
		name = osv.GoStdModulePath
	case cmdModule:
		name = osv.GoCmdModulePath
	}
	return osv.Affected{
		Module: osv.Module{
			Path:      name,
			Ecosystem: osv.GoEcosystem,
		},
		Ranges: AffectedRanges(m.Versions),
		EcosystemSpecific: osv.EcosystemSpecific{
			Packages: toOSVPackages(m.Packages),
		},
	}
}


================================================
FILE: gopls/internal/vulncheck/vulntest/db_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vulntest

import (
	"context"
	"encoding/json"
	"flag"
	"os"
	"path/filepath"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
)

var update = flag.Bool("update", false, "update golden files in testdata/")

func TestNewDatabase(t *testing.T) {
	ctx := context.Background()

	in, err := os.ReadFile("testdata/report.yaml")
	if err != nil {
		t.Fatal(err)
	}
	in = append([]byte("-- GO-2020-0001.yaml --\n"), in...)

	db, err := NewDatabase(ctx, in)
	if err != nil {
		t.Fatal(err)
	}
	defer db.Clean()
	dbpath := protocol.DocumentURI(db.URI()).Path()

	// The generated JSON file will be in DB/GO-2022-0001.json.
	got := readOSVEntry(t, filepath.Join(dbpath, "GO-2020-0001.json"))
	got.Modified = time.Time{}

	if *update {
		updateTestData(t, got, "testdata/GO-2020-0001.json")
	}

	want := readOSVEntry(t, "testdata/GO-2020-0001.json")
	want.Modified = time.Time{}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("mismatch (-want +got):\n%s", diff)
	}
}

func updateTestData(t *testing.T, got *osv.Entry, fname string) {
	content, err := json.MarshalIndent(got, "", "\t")
	if err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(fname, content, 0666); err != nil {
		t.Fatal(err)
	}
	t.Logf("updated %v", fname)
}

func readOSVEntry(t *testing.T, filename string) *osv.Entry {
	t.Helper()
	content, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	var entry osv.Entry
	if err := json.Unmarshal(content, &entry); err != nil {
		t.Fatal(err)
	}
	return &entry
}


================================================
FILE: gopls/internal/vulncheck/vulntest/report.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vulntest

import (
	"fmt"
	"io"
	"os"
	"strings"
	"time"

	"golang.org/x/mod/semver"
	"golang.org/x/tools/gopls/internal/vulncheck/osv"
	"gopkg.in/yaml.v3"
)

//
// The following was selectively copied from golang.org/x/vulndb/internal/report
//

// readReport reads a Report in YAML format.
func readReport(in io.Reader) (*Report, error) {
	d := yaml.NewDecoder(in)
	// Require that all fields in the file are in the struct.
	// This corresponds to v2's UnmarshalStrict.
	d.KnownFields(true)
	var r Report
	if err := d.Decode(&r); err != nil {
		return nil, fmt.Errorf("yaml.Decode: %v", err)
	}
	return &r, nil
}

// Report represents a vulnerability report in the vulndb.
// See https://go.googlesource.com/vulndb/+/refs/heads/master/doc/format.md
type Report struct {
	ID string `yaml:",omitempty"`

	Modules []*Module `yaml:",omitempty"`

	// Summary is a short phrase describing the vulnerability.
	Summary string `yaml:",omitempty"`

	// Description is the CVE description from an existing CVE. If we are
	// assigning a CVE ID ourselves, use CVEMetadata.Description instead.
	Description string     `yaml:",omitempty"`
	Published   time.Time  `yaml:",omitempty"`
	Withdrawn   *time.Time `yaml:",omitempty"`

	References []*Reference `yaml:",omitempty"`
}

// Write writes r to filename in YAML format.
func (r *Report) Write(filename string) (err error) {
	f, err := os.Create(filename)
	if err != nil {
		return err
	}
	err = r.encode(f)
	err2 := f.Close()
	if err == nil {
		err = err2
	}
	return err
}

// ToString encodes r to a YAML string.
func (r *Report) ToString() (string, error) {
	var b strings.Builder
	if err := r.encode(&b); err != nil {
		return "", err
	}
	return b.String(), nil
}

func (r *Report) encode(w io.Writer) error {
	e := yaml.NewEncoder(w)
	defer e.Close()
	e.SetIndent(4)
	return e.Encode(r)
}

type VersionRange struct {
	Introduced Version `yaml:"introduced,omitempty"`
	Fixed      Version `yaml:"fixed,omitempty"`
}

type Module struct {
	Module   string         `yaml:",omitempty"`
	Versions []VersionRange `yaml:",omitempty"`
	Packages []*Package     `yaml:",omitempty"`
}

type Package struct {
	Package string   `yaml:",omitempty"`
	GOOS    []string `yaml:"goos,omitempty"`
	GOARCH  []string `yaml:"goarch,omitempty"`
	// Symbols originally identified as vulnerable.
	Symbols []string `yaml:",omitempty"`
	// Additional vulnerable symbols, computed from Symbols via static analysis
	// or other technique.
	DerivedSymbols []string `yaml:"derived_symbols,omitempty"`
}

// Version is a SemVer 2.0.0 semantic version with no leading "v" prefix,
// as used by OSV.
type Version string

// V returns the version with a "v" prefix.
func (v Version) V() string {
	return "v" + string(v)
}

// IsValid reports whether v is a valid semantic version string.
func (v Version) IsValid() bool {
	return semver.IsValid(v.V())
}

// Before reports whether v < v2.
func (v Version) Before(v2 Version) bool {
	return semver.Compare(v.V(), v2.V()) < 0
}

// Canonical returns the canonical formatting of the version.
func (v Version) Canonical() string {
	return strings.TrimPrefix(semver.Canonical(v.V()), "v")
}

// A Reference is a link to some external resource.
//
// For ease of typing, References are represented in the YAML as a
// single-element mapping of type to URL.
type Reference osv.Reference

func (r *Reference) MarshalYAML() (any, error) {
	return map[string]string{
		strings.ToLower(string(r.Type)): r.URL,
	}, nil
}

func (r *Reference) UnmarshalYAML(n *yaml.Node) (err error) {
	if n.Kind != yaml.MappingNode || len(n.Content) != 2 || n.Content[0].Kind != yaml.ScalarNode || n.Content[1].Kind != yaml.ScalarNode {
		return &yaml.TypeError{Errors: []string{
			fmt.Sprintf("line %d: report.Reference must contain a mapping with one value", n.Line),
		}}
	}
	r.Type = osv.ReferenceType(strings.ToUpper(n.Content[0].Value))
	r.URL = n.Content[1].Value
	return nil
}


================================================
FILE: gopls/internal/vulncheck/vulntest/report_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vulntest

import (
	"bytes"
	"io"
	"os"
	"path/filepath"
	"testing"

	"github.com/google/go-cmp/cmp"
)

func readAll(t *testing.T, filename string) io.Reader {
	d, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	return bytes.NewReader(d)
}

func TestRoundTrip(t *testing.T) {
	// A report shouldn't change after being read and then written.
	in := filepath.Join("testdata", "report.yaml")
	r, err := readReport(readAll(t, in))
	if err != nil {
		t.Fatal(err)
	}
	out := filepath.Join(t.TempDir(), "report.yaml")
	if err := r.Write(out); err != nil {
		t.Fatal(err)
	}

	want, err := os.ReadFile(in)
	if err != nil {
		t.Fatal(err)
	}
	got, err := os.ReadFile(out)
	if err != nil {
		t.Fatal(err)
	}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("mismatch (-want, +got):\n%s", diff)
	}
}


================================================
FILE: gopls/internal/vulncheck/vulntest/stdlib.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vulntest

import (
	"strings"

	"golang.org/x/mod/module"
)

// maybeStdlib reports whether the given import path could be part of the Go
// standard library, by reporting whether the first component lacks a '.'.
func maybeStdlib(path string) bool {
	if err := module.CheckImportPath(path); err != nil {
		return false
	}
	if i := strings.IndexByte(path, '/'); i != -1 {
		path = path[:i]
	}
	return !strings.Contains(path, ".")
}


================================================
FILE: gopls/internal/vulncheck/vulntest/stdlib_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package vulntest

import "testing"

func TestMaybeStdlib(t *testing.T) {
	for _, test := range []struct {
		in   string
		want bool
	}{
		{"", false},
		{"math/crypto", true},
		{"github.com/pkg/errors", false},
		{"Path is unknown", false},
	} {
		got := maybeStdlib(test.in)
		if got != test.want {
			t.Errorf("%q: got %t, want %t", test.in, got, test.want)
		}
	}
}


================================================
FILE: gopls/internal/vulncheck/vulntest/testdata/GO-2020-0001.json
================================================
{
	"id": "GO-2020-0001",
	"modified": "0001-01-01T00:00:00Z",
	"published": "0001-01-01T00:00:00Z",
	"details": "The default Formatter for the Logger middleware (LoggerConfig.Formatter),\nwhich is included in the Default engine, allows attackers to inject arbitrary\nlog entries by manipulating the request path.\n",
	"affected": [
		{
			"package": {
				"name": "github.com/gin-gonic/gin",
				"ecosystem": "Go"
			},
			"ranges": [
				{
					"type": "SEMVER",
					"events": [
						{
							"introduced": "0"
						},
						{
							"fixed": "1.6.0"
						}
					]
				}
			],
			"ecosystem_specific": {
				"imports": [
					{
						"path": "github.com/gin-gonic/gin",
						"symbols": [
							"defaultLogFormatter"
						]
					}
				]
			}
		}
	],
	"references": [
		{
			"type": "FIX",
			"url": "https://github.com/gin-gonic/gin/pull/1234"
		},
		{
			"type": "FIX",
			"url": "https://github.com/gin-gonic/gin/commit/abcdefg"
		}
	],
	"database_specific": {
		"url": "https://pkg.go.dev/vuln/GO-2020-0001"
	}
}

================================================
FILE: gopls/internal/vulncheck/vulntest/testdata/report.yaml
================================================
modules:
    - module: github.com/gin-gonic/gin
      versions:
        - fixed: 1.6.0
      packages:
        - package: github.com/gin-gonic/gin
          symbols:
            - defaultLogFormatter
description: |
    The default Formatter for the Logger middleware (LoggerConfig.Formatter),
    which is included in the Default engine, allows attackers to inject arbitrary
    log entries by manipulating the request path.
references:
    - fix: https://github.com/gin-gonic/gin/pull/1234
    - fix: https://github.com/gin-gonic/gin/commit/abcdefg


================================================
FILE: gopls/internal/work/completion.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package work

import (
	"context"
	"errors"
	"fmt"
	"io/fs"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func Completion(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, position protocol.Position) (*protocol.CompletionList, error) {
	ctx, done := event.Start(ctx, "work.Completion")
	defer done()

	// Get the position of the cursor.
	pw, err := snapshot.ParseWork(ctx, fh)
	if err != nil {
		return nil, fmt.Errorf("getting go.work file handle: %w", err)
	}
	cursor, err := pw.Mapper.PositionOffset(position)
	if err != nil {
		return nil, fmt.Errorf("computing cursor offset: %w", err)
	}

	// Find the use statement the user is in.
	use, pathStart, _ := usePath(pw, cursor, cursor)
	if use == nil {
		return &protocol.CompletionList{}, nil
	}
	completingFrom := use.Path[:cursor-pathStart]

	// We're going to find the completions of the user input
	// (completingFrom) by doing a walk on the innermost directory
	// of the given path, and comparing the found paths to make sure
	// that they match the component of the path after the
	// innermost directory.
	//
	// We'll maintain two paths when doing this: pathPrefixSlash
	// is essentially the path the user typed in, and pathPrefixAbs
	// is the path made absolute from the go.work directory.

	pathPrefixSlash := completingFrom
	pathPrefixAbs := filepath.FromSlash(pathPrefixSlash)
	if !filepath.IsAbs(pathPrefixAbs) {
		pathPrefixAbs = filepath.Join(pw.URI.DirPath(), pathPrefixAbs)
	}

	// pathPrefixDir is the directory that will be walked to find matches.
	// If pathPrefixSlash is not explicitly a directory boundary (is either equivalent to "." or
	// ends in a separator) we need to examine its parent directory to find sibling files that
	// match.
	depthBound := 5
	pathPrefixDir, pathPrefixBase := pathPrefixAbs, ""
	pathPrefixSlashDir := pathPrefixSlash
	if filepath.Clean(pathPrefixSlash) != "." && !strings.HasSuffix(pathPrefixSlash, "/") {
		depthBound++
		pathPrefixDir, pathPrefixBase = filepath.Split(pathPrefixAbs)
		pathPrefixSlashDir = dirNonClean(pathPrefixSlash)
	}

	var completions []string
	// Stop traversing deeper once we've hit 10k files to try to stay generally under 100ms.
	const numSeenBound = 10000
	var numSeen int
	stopWalking := errors.New("hit numSeenBound")
	err = filepath.WalkDir(pathPrefixDir, func(wpath string, entry fs.DirEntry, err error) error {
		if err != nil {
			// golang/go#64225: an error reading a dir is expected, as the user may
			// be typing out a use directive for a directory that doesn't exist.
			return nil
		}
		if numSeen > numSeenBound {
			// Stop traversing if we hit bound.
			return stopWalking
		}
		numSeen++

		// rel is the path relative to pathPrefixDir.
		// Make sure that it has pathPrefixBase as a prefix
		// otherwise it won't match the beginning of the
		// base component of the path the user typed in.
		rel := strings.TrimPrefix(wpath[len(pathPrefixDir):], string(filepath.Separator))
		if entry.IsDir() && wpath != pathPrefixDir && !strings.HasPrefix(rel, pathPrefixBase) {
			return filepath.SkipDir
		}

		// Check for a match (a module directory).
		if filepath.Base(rel) == "go.mod" {
			relDir := strings.TrimSuffix(dirNonClean(rel), string(os.PathSeparator))
			completionPath := join(pathPrefixSlashDir, filepath.ToSlash(relDir))

			if !strings.HasPrefix(completionPath, completingFrom) {
				return nil
			}
			if strings.HasSuffix(completionPath, "/") {
				// Don't suggest paths that end in "/". This happens
				// when the input is a path that ends in "/" and
				// the completion is empty.
				return nil
			}
			completion := completionPath[len(completingFrom):]
			if completingFrom == "" && !strings.HasPrefix(completion, "./") {
				// Bias towards "./" prefixes.
				completion = join(".", completion)
			}

			completions = append(completions, completion)
		}

		if depth := strings.Count(rel, string(filepath.Separator)); depth >= depthBound {
			return filepath.SkipDir
		}
		return nil
	})
	if err != nil && !errors.Is(err, stopWalking) {
		return nil, fmt.Errorf("walking to find completions: %w", err)
	}

	sort.Strings(completions)

	items := []protocol.CompletionItem{} // must be a slice
	for _, c := range completions {
		items = append(items, protocol.CompletionItem{
			Label:      c,
			InsertText: c,
		})
	}
	return &protocol.CompletionList{Items: items}, nil
}

// dirNonClean is filepath.Dir, without the Clean at the end.
func dirNonClean(path string) string {
	vol := filepath.VolumeName(path)
	i := len(path) - 1
	for i >= len(vol) && !os.IsPathSeparator(path[i]) {
		i--
	}
	return path[len(vol) : i+1]
}

func join(a, b string) string {
	if a == "" {
		return b
	}
	if b == "" {
		return a
	}
	return strings.TrimSuffix(a, "/") + "/" + b
}


================================================
FILE: gopls/internal/work/diagnostics.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package work

import (
	"context"
	"fmt"
	"os"
	"path/filepath"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func Diagnostics(ctx context.Context, snapshot *cache.Snapshot) (map[protocol.DocumentURI][]*cache.Diagnostic, error) {
	ctx, done := event.Start(ctx, "work.Diagnostics", snapshot.Labels()...)
	defer done()

	reports := map[protocol.DocumentURI][]*cache.Diagnostic{}
	uri := snapshot.View().GoWork()
	if uri == "" {
		return nil, nil
	}
	fh, err := snapshot.ReadFile(ctx, uri)
	if err != nil {
		return nil, err
	}
	reports[fh.URI()] = []*cache.Diagnostic{}
	diagnostics, err := diagnoseOne(ctx, snapshot, fh)
	if err != nil {
		return nil, err
	}
	for _, d := range diagnostics {
		fh, err := snapshot.ReadFile(ctx, d.URI)
		if err != nil {
			return nil, err
		}
		reports[fh.URI()] = append(reports[fh.URI()], d)
	}

	return reports, nil
}

func diagnoseOne(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]*cache.Diagnostic, error) {
	pw, err := snapshot.ParseWork(ctx, fh)
	if err != nil {
		if pw == nil || len(pw.ParseErrors) == 0 {
			return nil, err
		}
		return pw.ParseErrors, nil
	}

	// Add diagnostic if a directory does not contain a module.
	var diagnostics []*cache.Diagnostic
	for _, use := range pw.File.Use {
		rng, err := pw.Mapper.OffsetRange(use.Syntax.Start.Byte, use.Syntax.End.Byte)
		if err != nil {
			return nil, err
		}

		modfh, err := snapshot.ReadFile(ctx, modFileURI(pw, use))
		if err != nil {
			return nil, err
		}
		if _, err := modfh.Content(); err != nil && os.IsNotExist(err) {
			diagnostics = append(diagnostics, &cache.Diagnostic{
				URI:      fh.URI(),
				Range:    rng,
				Severity: protocol.SeverityError,
				Source:   cache.WorkFileError,
				Message:  fmt.Sprintf("directory %v does not contain a module", use.Path),
			})
		}
	}
	return diagnostics, nil
}

func modFileURI(pw *cache.ParsedWorkFile, use *modfile.Use) protocol.DocumentURI {
	workdir := pw.URI.DirPath()

	modroot := filepath.FromSlash(use.Path)
	if !filepath.IsAbs(modroot) {
		modroot = filepath.Join(workdir, modroot)
	}

	return protocol.URIFromPath(filepath.Join(modroot, "go.mod"))
}


================================================
FILE: gopls/internal/work/format.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package work

import (
	"context"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/event"
)

func Format(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle) ([]protocol.TextEdit, error) {
	ctx, done := event.Start(ctx, "work.Format")
	defer done()

	pw, err := snapshot.ParseWork(ctx, fh)
	if err != nil {
		return nil, err
	}
	formatted := modfile.Format(pw.File.Syntax)
	// Calculate the edits to be made due to the change.
	diffs := diff.Bytes(pw.Mapper.Content, formatted)
	return protocol.EditsFromDiffEdits(pw.Mapper, diffs)
}


================================================
FILE: gopls/internal/work/hover.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package work

import (
	"bytes"
	"context"
	"fmt"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/gopls/internal/cache"
	"golang.org/x/tools/gopls/internal/file"
	"golang.org/x/tools/gopls/internal/protocol"
	"golang.org/x/tools/internal/event"
)

func Hover(ctx context.Context, snapshot *cache.Snapshot, fh file.Handle, rng protocol.Range) (*protocol.Hover, error) {
	// We only provide hover information for the view's go.work file.
	if fh.URI() != snapshot.View().GoWork() {
		return nil, nil
	}

	ctx, done := event.Start(ctx, "work.Hover")
	defer done()

	// Get the position of the cursor.
	pw, err := snapshot.ParseWork(ctx, fh)
	if err != nil {
		return nil, fmt.Errorf("getting go.work file handle: %w", err)
	}
	startOffset, endOffset, err := pw.Mapper.RangeOffsets(rng)
	if err != nil {
		return nil, fmt.Errorf("computing cursor offset: %w", err)
	}

	// Confirm that the cursor is inside a use statement, and then find
	// the position of the use statement's directory path.
	use, pathStart, pathEnd := usePath(pw, startOffset, endOffset)

	// The cursor position is not on a use statement.
	if use == nil {
		return nil, nil
	}

	// Get the mod file denoted by the use.
	modfh, err := snapshot.ReadFile(ctx, modFileURI(pw, use))
	if err != nil {
		return nil, fmt.Errorf("getting modfile handle: %w", err)
	}
	pm, err := snapshot.ParseMod(ctx, modfh)
	if err != nil {
		return nil, fmt.Errorf("getting modfile handle: %w", err)
	}
	if pm.File.Module == nil {
		return nil, fmt.Errorf("modfile has no module declaration")
	}
	mod := pm.File.Module.Mod

	// Get the range to highlight for the hover.
	pathRng, err := pw.Mapper.OffsetRange(pathStart, pathEnd)
	if err != nil {
		return nil, err
	}
	options := snapshot.Options()
	return &protocol.Hover{
		Contents: protocol.MarkupContent{
			Kind:  options.PreferredContentFormat,
			Value: mod.Path,
		},
		Range: pathRng,
	}, nil
}

func usePath(pw *cache.ParsedWorkFile, startOffset, endOffset int) (use *modfile.Use, pathStart, pathEnd int) {
	for _, u := range pw.File.Use {
		path := []byte(u.Path)
		s, e := u.Syntax.Start.Byte, u.Syntax.End.Byte
		i := bytes.Index(pw.Mapper.Content[s:e], path)
		if i == -1 {
			// This should not happen.
			continue
		}
		// Shift the start position to the location of the
		// module directory within the use statement.
		pathStart, pathEnd = s+i, s+i+len(path)
		if pathStart <= startOffset && endOffset <= pathEnd {
			return u, pathStart, pathEnd
		}
	}
	return nil, 0, 0
}


================================================
FILE: gopls/main.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Gopls (pronounced “go please”) is an LSP server for Go.
// The Language Server Protocol allows any text editor
// to be extended with IDE-like features;
// see https://langserver.org/ for details.
//
// See https://go.dev/gopls for comprehensive documentation on Gopls.
package main

import (
	"context"
	"log"
	"os"

	"golang.org/x/telemetry"
	"golang.org/x/telemetry/counter"
	"golang.org/x/tools/gopls/internal/cmd"
	"golang.org/x/tools/gopls/internal/filecache"
	versionpkg "golang.org/x/tools/gopls/internal/version"
	"golang.org/x/tools/internal/tool"
)

var version = "" // if set by the linker, overrides the gopls version

func main() {
	versionpkg.VersionOverride = version

	telemetry.Start(telemetry.Config{
		ReportCrashes: true,
		Upload:        true,
	})

	// Force early creation of the filecache and refuse to start
	// if there were unexpected errors such as ENOSPC. This
	// minimizes the window of exposure to deletion of the
	// executable, and ensures that all subsequent calls to
	// filecache.Get cannot fail for these two reasons;
	// see issue #67433.
	//
	// This leaves only one likely cause for later failures:
	// deletion of the cache while gopls is running. If the
	// problem continues, we could periodically stat the cache
	// directory (for example at the start of every RPC) and
	// either re-create it or just fail the RPC with an
	// informative error and terminate the process.
	if _, err := filecache.Get("nonesuch", [32]byte{}); err != nil && err != filecache.ErrNotFound {
		counter.Inc("gopls/nocache")
		log.Fatalf("gopls cannot access its persistent index (disk full?): %v", err)
	}

	ctx := context.Background()
	tool.Main(ctx, cmd.New(), os.Args[1:])
}


================================================
FILE: imports/forward.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package imports implements a Go pretty-printer (like package "go/format")
// that also adds or removes import statements as necessary.
package imports // import "golang.org/x/tools/imports"

import (
	"log"
	"os"

	"golang.org/x/tools/internal/gocommand"
	intimp "golang.org/x/tools/internal/imports"
)

// Options specifies options for processing files.
type Options struct {
	Fragment  bool // Accept fragment of a source file (no package statement)
	AllErrors bool // Report all errors (not just the first 10 on different lines)

	Comments  bool // Print comments (true if nil *Options provided)
	TabIndent bool // Use tabs for indent (true if nil *Options provided)
	TabWidth  int  // Tab width (8 if nil *Options provided)

	FormatOnly bool // Disable the insertion and deletion of imports
}

// Debug controls verbose logging.
var Debug = false

// LocalPrefix is a comma-separated string of import path prefixes, which, if
// set, instructs Process to sort the import paths with the given prefixes
// into another group after 3rd-party packages.
var LocalPrefix string

// Process formats and adjusts imports for the provided file.
// If opt is nil the defaults are used, and if src is nil the source
// is read from the filesystem.
//
// Note that filename's directory influences which imports can be chosen,
// so it is important that filename be accurate.
// To process data “as if” it were in filename, pass the data as a non-nil src.
func Process(filename string, src []byte, opt *Options) ([]byte, error) {
	var err error
	if src == nil {
		src, err = os.ReadFile(filename)
		if err != nil {
			return nil, err
		}
	}
	if opt == nil {
		opt = &Options{Comments: true, TabIndent: true, TabWidth: 8}
	}
	intopt := &intimp.Options{
		Env: &intimp.ProcessEnv{
			GocmdRunner: &gocommand.Runner{},
		},
		LocalPrefix: LocalPrefix,
		AllErrors:   opt.AllErrors,
		Comments:    opt.Comments,
		FormatOnly:  opt.FormatOnly,
		Fragment:    opt.Fragment,
		TabIndent:   opt.TabIndent,
		TabWidth:    opt.TabWidth,
	}
	if Debug {
		intopt.Env.Logf = log.Printf
	}
	return intimp.Process(filename, src, intopt)
}

// VendorlessPath returns the devendorized version of the import path ipath.
// For example, VendorlessPath("foo/barbendor/a/b") return "a/b".
func VendorlessPath(ipath string) string {
	return intimp.VendorlessPath(ipath)
}


================================================
FILE: internal/aliases/aliases.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package aliases

import (
	"go/token"
	"go/types"
)

// New creates a new TypeName in Package pkg that
// is an alias for the type rhs.
func New(pos token.Pos, pkg *types.Package, name string, rhs types.Type, tparams []*types.TypeParam) *types.TypeName {
	tname := types.NewTypeName(pos, pkg, name, nil)
	types.NewAlias(tname, rhs).SetTypeParams(tparams)
	return tname
}


================================================
FILE: internal/aliases/aliases_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package aliases_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/aliases"
	"golang.org/x/tools/internal/testenv"
)

// TestNew tests that [aliases.New] creates a *types.Alias of a type
// whose underlying and Unaliased type is *Named.
func TestNew(t *testing.T) {
	const source = `
	package p

	type Named int
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("p", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	expr := `*Named`
	tv, err := types.Eval(fset, pkg, 0, expr)
	if err != nil {
		t.Fatalf("Eval(%s) failed: %v", expr, err)
	}

	A := aliases.New(token.NoPos, pkg, "A", tv.Type, nil)
	if got, want := A.Name(), "A"; got != want {
		t.Errorf("Expected A.Name()==%q. got %q", want, got)
	}

	if got, want := A.Type().Underlying(), tv.Type; got != want {
		t.Errorf("Expected A.Type().Underlying()==%q. got %q", want, got)
	}
	if got, want := types.Unalias(A.Type()), tv.Type; got != want {
		t.Errorf("Expected Unalias(A)==%q. got %q", want, got)
	}
	if _, ok := A.Type().(*types.Alias); !ok {
		t.Errorf("Expected A.Type() to be a *types.Alias; got %q", A.Type())
	}
}

// TestNewParameterizedAlias tests that [aliases.New] can create a parameterized alias
// A[T] of a type whose underlying and Unaliased type is *T. The test then
// instantiates A[Named] and checks that the underlying and Unaliased type
// of A[Named] is *Named.
//
// Requires aliastypeparams GOEXPERIMENT.
func TestNewParameterizedAlias(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)
	if testenv.Go1Point() == 23 {
		testenv.NeedsGoExperiment(t, "aliastypeparams")
	}

	const source = `
	package p

	type Named int
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("p", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// type A[T ~int] = *T
	tparam := types.NewTypeParam(
		types.NewTypeName(token.NoPos, pkg, "T", nil),
		types.NewUnion([]*types.Term{types.NewTerm(true, types.Typ[types.Int])}),
	)
	ptrT := types.NewPointer(tparam)
	A := aliases.New(token.NoPos, pkg, "A", ptrT, []*types.TypeParam{tparam})
	if got, want := A.Name(), "A"; got != want {
		t.Errorf("New: got %q, want %q", got, want)
	}

	if got, want := A.Type().Underlying(), ptrT; !types.Identical(got, want) {
		t.Errorf("A.Type().Underlying (%q) is not identical to %q", got, want)
	}
	if got, want := types.Unalias(A.Type()), ptrT; !types.Identical(got, want) {
		t.Errorf("Unalias(A)==%q is not identical to %q", got, want)
	}

	if _, ok := A.Type().(*types.Alias); !ok {
		t.Errorf("Expected A.Type() to be a types.Alias(). got %q", A.Type())
	}

	pkg.Scope().Insert(A) // Add A to pkg so it is available to types.Eval.

	named, ok := pkg.Scope().Lookup("Named").(*types.TypeName)
	if !ok {
		t.Fatalf("Failed to Lookup(%q) in package %s", "Named", pkg)
	}
	ptrNamed := types.NewPointer(named.Type())

	const expr = `A[Named]`
	tv, err := types.Eval(fset, pkg, 0, expr)
	if err != nil {
		t.Fatalf("Eval(%s) failed: %v", expr, err)
	}

	if got, want := tv.Type.Underlying(), ptrNamed; !types.Identical(got, want) {
		t.Errorf("A[Named].Type().Underlying (%q) is not identical to %q", got, want)
	}
	if got, want := types.Unalias(tv.Type), ptrNamed; !types.Identical(got, want) {
		t.Errorf("Unalias(A[Named])==%q is not identical to %q", got, want)
	}
}


================================================
FILE: internal/analysis/README
================================================

This is not a package. Do not add *.go files here.

================================================
FILE: internal/analysis/analyzerutil/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package analyzerutil provides implementation helpers for analyzers.
package analyzerutil


================================================
FILE: internal/analysis/analyzerutil/extractdoc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analyzerutil

import (
	"fmt"
	"go/parser"
	"go/token"
	"strings"
)

// MustExtractDoc is like [ExtractDoc] but it panics on error.
//
// To use, define a doc.go file such as:
//
//	// Package halting defines an analyzer of program termination.
//	//
//	// # Analyzer halting
//	//
//	// halting: reports whether execution will halt.
//	//
//	// The halting analyzer reports a diagnostic for functions
//	// that run forever. To suppress the diagnostics, try inserting
//	// a 'break' statement into each loop.
//	package halting
//
//	import _ "embed"
//
//	//go:embed doc.go
//	var doc string
//
// And declare your analyzer as:
//
//	var Analyzer = &analysis.Analyzer{
//		Name:             "halting",
//		Doc:              analyzerutil.MustExtractDoc(doc, "halting"),
//		...
//	}
func MustExtractDoc(content, name string) string {
	doc, err := ExtractDoc(content, name)
	if err != nil {
		panic(err)
	}
	return doc
}

// ExtractDoc extracts a section of a package doc comment from the
// provided contents of an analyzer package's doc.go file.
//
// A section is a portion of the comment between one heading and
// the next, using this form:
//
//	# Analyzer NAME
//
//	NAME: SUMMARY
//
//	Full description...
//
// where NAME matches the name argument, and SUMMARY is a brief
// verb-phrase that describes the analyzer. The following lines, up
// until the next heading or the end of the comment, contain the full
// description. ExtractDoc returns the portion following the colon,
// which is the form expected by Analyzer.Doc.
//
// Example:
//
//	# Analyzer printf
//
//	printf: checks consistency of calls to printf
//
//	The printf analyzer checks consistency of calls to printf.
//	Here is the complete description...
//
// This notation allows a single doc comment to provide documentation
// for multiple analyzers, each in its own section.
// The HTML anchors generated for each heading are predictable.
//
// It returns an error if the content was not a valid Go source file
// containing a package doc comment with a heading of the required
// form.
//
// This machinery enables the package documentation (typically
// accessible via the web at https://pkg.go.dev/) and the command
// documentation (typically printed to a terminal) to be derived from
// the same source and formatted appropriately.
func ExtractDoc(content, name string) (string, error) {
	if content == "" {
		return "", fmt.Errorf("empty Go source file")
	}
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "", content, parser.ParseComments|parser.PackageClauseOnly)
	if err != nil {
		return "", fmt.Errorf("not a Go source file")
	}
	if f.Doc == nil {
		return "", fmt.Errorf("Go source file has no package doc comment")
	}
	for section := range strings.SplitSeq(f.Doc.Text(), "\n# ") {
		if body := strings.TrimPrefix(section, "Analyzer "+name); body != section &&
			body != "" &&
			body[0] == '\r' || body[0] == '\n' {
			body = strings.TrimSpace(body)
			rest := strings.TrimPrefix(body, name+":")
			if rest == body {
				return "", fmt.Errorf("'Analyzer %s' heading not followed by '%s: summary...' line", name, name)
			}
			return strings.TrimSpace(rest), nil
		}
	}
	return "", fmt.Errorf("package doc comment contains no 'Analyzer %s' heading", name)
}


================================================
FILE: internal/analysis/analyzerutil/extractdoc_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analyzerutil_test

import (
	"testing"

	"golang.org/x/tools/internal/analysis/analyzerutil"
)

func TestExtractDoc(t *testing.T) {
	const multi = `// Copyright

//+build tag

// Package foo
//
// # Irrelevant heading
//
// This is irrelevant doc.
//
// # Analyzer nocolon
//
// This one has the wrong form for this line.
//
// # Analyzer food
//
// food: reports dining opportunities
//
// This is the doc for analyzer 'food'.
//
// # Analyzer foo
//
// foo: reports diagnostics
//
// This is the doc for analyzer 'foo'.
//
// # Analyzer bar
//
// bar: reports drinking opportunities
//
// This is the doc for analyzer 'bar'.
package blah

var x = syntax error
`

	for _, test := range []struct {
		content, name string
		want          string // doc or "error: %w" string
	}{
		{"", "foo",
			"error: empty Go source file"},
		{"//foo", "foo",
			"error: not a Go source file"},
		{"//foo\npackage foo", "foo",
			"error: package doc comment contains no 'Analyzer foo' heading"},
		{multi, "foo",
			"reports diagnostics\n\nThis is the doc for analyzer 'foo'."},
		{multi, "bar",
			"reports drinking opportunities\n\nThis is the doc for analyzer 'bar'."},
		{multi, "food",
			"reports dining opportunities\n\nThis is the doc for analyzer 'food'."},
		{multi, "nope",
			"error: package doc comment contains no 'Analyzer nope' heading"},
		{multi, "nocolon",
			"error: 'Analyzer nocolon' heading not followed by 'nocolon: summary...' line"},
	} {
		got, err := analyzerutil.ExtractDoc(test.content, test.name)
		if err != nil {
			got = "error: " + err.Error()
		}
		if test.want != got {
			t.Errorf("ExtractDoc(%q) returned <<%s>>, want <<%s>>, given input <<%s>>",
				test.name, got, test.want, test.content)
		}
	}
}


================================================
FILE: internal/analysis/analyzerutil/readfile.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analyzerutil

// This file defines helpers for calling [analysis.Pass.ReadFile].

import (
	"go/token"
	"os"

	"golang.org/x/tools/go/analysis"
)

// ReadFile reads a file and adds it to the FileSet in pass
// so that we can report errors against it using lineStart.
func ReadFile(pass *analysis.Pass, filename string) ([]byte, *token.File, error) {
	readFile := pass.ReadFile
	if readFile == nil {
		readFile = os.ReadFile
	}
	content, err := readFile(filename)
	if err != nil {
		return nil, nil, err
	}
	tf := pass.Fset.AddFile(filename, -1, len(content))
	tf.SetLinesForContent(content)
	return content, tf, nil
}


================================================
FILE: internal/analysis/analyzerutil/version.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package analyzerutil

import (
	"go/ast"
	"strings"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/versions"
)

// FileUsesGoVersion reports whether the specified file may use features of the
// specified version of Go (e.g. "go1.24").
//
// It returns false when version information is not available,
// such as for parsed files that are ignored by the type checker.
//
// Tip: we recommend using this check "late", just before calling
// pass.Report, rather than "early" (when entering each ast.File, or
// each candidate node of interest, during the traversal), because the
// operation is not free, yet is not a highly selective filter: the
// fraction of files that pass most version checks is high and
// increases over time.
func FileUsesGoVersion(pass *analysis.Pass, file *ast.File, version string) (_res bool) {
	fileVersion, ok := pass.TypesInfo.FileVersions[file]
	if !ok {
		return false // be conservative in the absence of information (e.g. IgnoredFiles)
	}

	// Standard packages that are part of toolchain bootstrapping
	// are not considered to use a version of Go later than the
	// current bootstrap toolchain version.
	// The bootstrap rule does not cover tests,
	// and some tests (e.g. debug/elf/file_test.go) rely on this.
	pkgpath := pass.Pkg.Path()
	if packagepath.IsStdPackage(pkgpath) &&
		stdlib.IsBootstrapPackage(pkgpath) && // (excludes "*_test" external test packages)
		!strings.HasSuffix(pass.Fset.File(file.Pos()).Name(), "_test.go") { // (excludes all tests)
		fileVersion = stdlib.BootstrapVersion.String() // package must bootstrap
	}

	return !versions.Before(fileVersion, version)
}


================================================
FILE: internal/analysis/driverutil/fix.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package driverutil defines implementation helper functions for
// analysis drivers such as unitchecker, {single,multi}checker, and
// analysistest.
package driverutil

// This file defines the -fix logic common to unitchecker and
// {single,multi}checker.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/parser"
	"go/printer"
	"go/token"
	"go/types"
	"log"
	"maps"
	"os"
	"sort"
	"strconv"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/internal/astutil/free"
	"golang.org/x/tools/internal/diff"
)

// FixAction abstracts a checker action (running one analyzer on one
// package) for the purposes of applying its diagnostics' fixes.
type FixAction struct {
	Name         string         // e.g. "analyzer@package"
	Pkg          *types.Package // (for import removal)
	Files        []*ast.File
	FileSet      *token.FileSet
	ReadFileFunc ReadFileFunc
	Diagnostics  []analysis.Diagnostic
}

// ApplyFixes attempts to apply the first suggested fix associated
// with each diagnostic reported by the specified actions.
// All fixes must have been validated by [ValidateFixes].
//
// Each fix is treated as an independent change; fixes are merged in
// an arbitrary deterministic order as if by a three-way diff tool
// such as the UNIX diff3 command or 'git merge'. Any fix that cannot be
// cleanly merged is discarded, in which case the final summary tells
// the user to re-run the tool.
// TODO(adonovan): make the checker tool re-run the analysis itself.
//
// When the same file is analyzed as a member of both a primary
// package "p" and a test-augmented package "p [p.test]", there may be
// duplicate diagnostics and fixes. One set of fixes will be applied
// and the other will be discarded; but re-running the tool may then
// show zero fixes, which may cause the confused user to wonder what
// happened to the other ones.
// TODO(adonovan): consider pre-filtering completely identical fixes.
//
// A common reason for overlapping fixes is duplicate additions of the
// same import. The merge algorithm may often cleanly resolve such
// fixes, coalescing identical edits, but the merge may sometimes be
// confused by nearby changes.
//
// Even when merging succeeds, there is no guarantee that the
// composition of the two fixes is semantically correct. Coalescing
// identical edits is appropriate for imports, but not for, say,
// increments to a counter variable; the correct resolution in that
// case might be to increment it twice.
//
// Or consider two fixes that each delete the penultimate reference to
// a local variable: each fix is sound individually, and they may be
// textually distant from each other, but when both are applied, the
// program is no longer valid because it has an unreferenced local
// variable. (ApplyFixes solves the analogous problem for imports by
// eliminating imports whose name is unreferenced in the remainder of
// the fixed file.)
//
// Merging depends on both the order of fixes and they order of edits
// within them. For example, if three fixes add import "a" twice and
// import "b" once, the two imports of "a" may be combined if they
// appear in order [a, a, b], or not if they appear as [a, b, a].
// TODO(adonovan): investigate an algebraic approach to imports;
// that is, for fixes to Go source files, convert changes within the
// import(...) portion of the file into semantic edits, compose those
// edits algebraically, then convert the result back to edits.
//
// applyFixes returns success if all fixes are valid, could be cleanly
// merged, and the corresponding files were successfully updated.
//
// If printDiff (from the -diff flag) is set, instead of updating the
// files it display the final patch composed of all the cleanly merged
// fixes. (It is tempting to factor printDiff as just a variant of
// writeFile that is provided the old and new content, but it's hard
// to generate a good summary that way.)
//
// TODO(adonovan): handle file-system level aliases such as symbolic
// links using robustio.FileID.
func ApplyFixes(actions []FixAction, writeFile func(filename string, content []byte) error, printDiff, verbose bool) error {
	generated := make(map[*token.File]bool)

	// Select fixes to apply.
	//
	// If there are several for a given Diagnostic, choose the first.
	// Preserve the order of iteration, for determinism.
	type fixact struct {
		fix *analysis.SuggestedFix
		act FixAction
	}
	var fixes []*fixact
	for _, act := range actions {
		for _, file := range act.Files {
			tokFile := act.FileSet.File(file.FileStart)
			// Memoize, since there may be many actions
			// for the same package (list of files).
			if _, seen := generated[tokFile]; !seen {
				generated[tokFile] = ast.IsGenerated(file)
			}
		}

		for _, diag := range act.Diagnostics {
			for i := range diag.SuggestedFixes {
				fix := &diag.SuggestedFixes[i]
				if i == 0 {
					fixes = append(fixes, &fixact{fix, act})
				} else {
					// TODO(adonovan): abstract the logger.
					log.Printf("%s: ignoring alternative fix %q", act.Name, fix.Message)
				}
			}
		}
	}

	// Read file content on demand, from the virtual
	// file system that fed the analyzer (see #62292).
	//
	// This cache assumes that all successful reads for the same
	// file name return the same content.
	// (It is tempting to group fixes by package and do the
	// merge/apply/format steps one package at a time, but
	// packages are not disjoint, due to test variants, so this
	// would not really address the issue.)
	baselineContent := make(map[string][]byte)
	getBaseline := func(readFile ReadFileFunc, filename string) ([]byte, error) {
		content, ok := baselineContent[filename]
		if !ok {
			var err error
			content, err = readFile(filename)
			if err != nil {
				return nil, err
			}
			baselineContent[filename] = content
		}
		return content, nil
	}

	// Apply each fix, updating the current state
	// only if the entire fix can be cleanly merged.
	var (
		accumulatedEdits = make(map[string][]diff.Edit)
		filePkgs         = make(map[string]*types.Package) // maps each file to an arbitrary package that includes it

		goodFixes    = 0 // number of fixes cleanly applied
		skippedFixes = 0 // number of fixes skipped (because e.g. edits a generated file)
	)
fixloop:
	for _, fixact := range fixes {
		// Skip a fix if any of its edits touch a generated file.
		for _, edit := range fixact.fix.TextEdits {
			file := fixact.act.FileSet.File(edit.Pos)
			if generated[file] {
				skippedFixes++
				continue fixloop
			}
		}

		// Convert analysis.TextEdits to diff.Edits, grouped by file.
		// Precondition: a prior call to validateFix succeeded.
		fileEdits := make(map[string][]diff.Edit)
		for _, edit := range fixact.fix.TextEdits {
			file := fixact.act.FileSet.File(edit.Pos)

			filePkgs[file.Name()] = fixact.act.Pkg

			baseline, err := getBaseline(fixact.act.ReadFileFunc, file.Name())
			if err != nil {
				log.Printf("skipping fix to file %s: %v", file.Name(), err)
				continue fixloop
			}

			// We choose to treat size mismatch as a serious error,
			// as it indicates a concurrent write to at least one file,
			// and possibly others (consider a git checkout, for example).
			if file.Size() != len(baseline) {
				return fmt.Errorf("concurrent file modification detected in file %s (size changed from %d -> %d bytes); aborting fix",
					file.Name(), file.Size(), len(baseline))
			}

			fileEdits[file.Name()] = append(fileEdits[file.Name()], diff.Edit{
				Start: file.Offset(edit.Pos),
				End:   file.Offset(edit.End),
				New:   string(edit.NewText),
			})
		}

		// Apply each set of edits by merging atop
		// the previous accumulated state.
		after := make(map[string][]diff.Edit)
		for file, edits := range fileEdits {
			if prev := accumulatedEdits[file]; len(prev) > 0 {
				merged, ok := diff.Merge(prev, edits)
				if !ok {
					// debugging
					if false {
						log.Printf("%s: fix %s conflicts", fixact.act.Name, fixact.fix.Message)
					}
					continue fixloop // conflict
				}
				edits = merged
			}
			after[file] = edits
		}

		// The entire fix applied cleanly; commit it.
		goodFixes++
		maps.Copy(accumulatedEdits, after)
		// debugging
		if false {
			log.Printf("%s: fix %s applied", fixact.act.Name, fixact.fix.Message)
		}
	}
	badFixes := len(fixes) - goodFixes - skippedFixes // number of fixes that could not be applied

	// Show diff or update files to final state.
	var files []string
	for file := range accumulatedEdits {
		files = append(files, file)
	}
	sort.Strings(files) // for deterministic -diff
	var filesUpdated, totalFiles int
	for _, file := range files {
		edits := accumulatedEdits[file]
		if len(edits) == 0 {
			continue // the diffs annihilated (a miracle?)
		}

		// Apply accumulated fixes.
		baseline := baselineContent[file] // (cache hit)
		final, err := diff.ApplyBytes(baseline, edits)
		if err != nil {
			log.Fatalf("internal error in diff.ApplyBytes: %v", err)
		}

		// Attempt to format each file.
		if formatted, err := FormatSourceRemoveImports(filePkgs[file], final); err == nil {
			final = formatted
		}

		if printDiff {
			// Since we formatted the file, we need to recompute the diff.
			unified := diff.Unified(file+" (old)", file+" (new)", string(baseline), string(final))
			// TODO(adonovan): abstract the I/O.
			os.Stdout.WriteString(unified)

		} else {
			// write file
			totalFiles++
			if err := writeFile(file, final); err != nil {
				log.Println(err)
				continue // (causes ApplyFix to return an error)
			}
			filesUpdated++
		}
	}

	// TODO(adonovan): consider returning a structured result that
	// maps each SuggestedFix to its status:
	// - invalid
	// - secondary, not selected
	// - applied
	// - had conflicts.
	// and a mapping from each affected file to:
	// - its final/original content pair, and
	// - whether formatting was successful.
	// Then file writes and the UI can be applied by the caller
	// in whatever form they like.

	// If victory was incomplete, report an error that indicates partial progress.
	//
	// badFixes > 0 indicates that we decided not to attempt some
	// fixes due to conflicts or failure to read the source; still
	// it's a relatively benign situation since the user can
	// re-run the tool, and we may still make progress.
	//
	// filesUpdated < totalFiles indicates that some file updates
	// failed. This should be rare, but is a serious error as it
	// may apply half a fix, or leave the files in a bad state.
	//
	// These numbers are potentially misleading:
	// The denominator includes duplicate conflicting fixes due to
	// common files in packages "p" and "p [p.test]", which may
	// have been fixed and won't appear in the re-run.
	// TODO(adonovan): eliminate identical fixes as an initial
	// filtering step.
	//
	// TODO(adonovan): should we log that n files were updated in case of total victory?
	if badFixes > 0 || filesUpdated < totalFiles {
		if printDiff {
			return fmt.Errorf("%d of %s skipped (e.g. due to conflicts)",
				badFixes,
				plural(len(fixes), "fix", "fixes"))
		} else {
			return fmt.Errorf("applied %d of %s; %s updated. (Re-run the command to apply more.)",
				goodFixes,
				plural(len(fixes), "fix", "fixes"),
				plural(filesUpdated, "file", "files"))
		}
	}

	if verbose {
		if skippedFixes > 0 {
			log.Printf("skipped %s that would edit generated files",
				plural(skippedFixes, "fix", "fixes"))
		}
		log.Printf("applied %s, updated %s",
			plural(len(fixes), "fix", "fixes"),
			plural(filesUpdated, "file", "files"))
	}

	return nil
}

// FormatSourceRemoveImports is a variant of [format.Source] that
// removes imports that became redundant when fixes were applied.
//
// Import removal is necessarily heuristic since we do not have type
// information for the fixed file and thus cannot accurately tell
// whether k is among the free names of T{k: 0}, which requires
// knowledge of whether T is a struct type.
//
// Like [imports.Process] (the core of x/tools/cmd/goimports), it also
// merges import decls.
func FormatSourceRemoveImports(pkg *types.Package, src []byte) ([]byte, error) {
	// This function was reduced from the "strict entire file"
	// path through [format.Source].

	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "fixed.go", src, parser.ParseComments|parser.SkipObjectResolution)
	if err != nil {
		return nil, err
	}

	ast.SortImports(fset, file)

	removeUnneededImports(fset, pkg, file)

	// TODO(adonovan): to generate cleaner edits when adding an import,
	// consider adding a call to imports.mergeImports; however, it does
	// cause comments to migrate.

	// printerNormalizeNumbers means to canonicalize number literal prefixes
	// and exponents while printing. See https://golang.org/doc/go1.13#gofmt.
	//
	// This value is defined in go/printer specifically for go/format and cmd/gofmt.
	const printerNormalizeNumbers = 1 << 30
	cfg := &printer.Config{
		Mode:     printer.UseSpaces | printer.TabIndent | printerNormalizeNumbers,
		Tabwidth: 8,
	}
	var buf bytes.Buffer
	if err := cfg.Fprint(&buf, fset, file); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

// removeUnneededImports removes import specs that are not referenced
// within the fixed file. It uses [free.Names] to heuristically
// approximate the set of imported names needed by the body of the
// file based only on syntax.
//
// pkg provides type information about the unmodified package, in
// particular the name that would implicitly be declared by a
// non-renaming import of a given existing dependency.
func removeUnneededImports(fset *token.FileSet, pkg *types.Package, file *ast.File) {
	// Map each existing dependency and its transitive dependencies to its default import name.
	// (We'll need this to interpret non-renaming imports.)
	packageNames := make(map[string]string)
	var visit func(pkg *types.Package)
	visit = func(pkg *types.Package) {
		if packageNames[pkg.Path()] == "" {
			packageNames[pkg.Path()] = pkg.Name()
			for _, imp := range pkg.Imports() {
				visit(imp)
			}
		}
	}
	for _, imp := range pkg.Imports() {
		visit(imp)
	}

	// Compute the set of free names of the file,
	// ignoring its import decls.
	freenames := make(map[string]bool)
	for _, decl := range file.Decls {
		if decl, ok := decl.(*ast.GenDecl); ok && decl.Tok == token.IMPORT {
			continue // skip import
		}

		// TODO(adonovan): we could do better than includeComplitIdents=false
		// since we have type information about the unmodified package,
		// which is a good source of heuristics.
		const includeComplitIdents = false
		maps.Copy(freenames, free.Names(decl, includeComplitIdents))
	}

	// Check whether each import's declared name is free (referenced) by the file.
	var deletions []func()
	for _, spec := range file.Imports {
		path, err := strconv.Unquote(spec.Path.Value)
		if err != nil {
			continue //  malformed import; ignore
		}
		explicit := "" // explicit PkgName, if any
		if spec.Name != nil {
			explicit = spec.Name.Name
		}
		name := explicit // effective PkgName
		if name == "" {
			// Non-renaming import: use package's default name.
			name = packageNames[path]
		}
		switch name {
		case "":
			continue // assume it's a new import, and we didn't find its default name while searching the import graph
		case ".":
			continue // dot imports are tricky
		case "_":
			continue // keep blank imports
		}
		if !freenames[name] {
			// Import's effective name is not free in (not used by) the file.
			// Enqueue it for deletion after the loop.
			deletions = append(deletions, func() {
				astutil.DeleteNamedImport(fset, file, explicit, path)
			})
		}
	}

	// Apply the deletions.
	for _, del := range deletions {
		del()
	}
}

// plural returns "n nouns", selecting the plural form as approriate.
func plural(n int, singular, plural string) string {
	if n == 1 {
		return "1 " + singular
	} else {
		return fmt.Sprintf("%d %s", n, plural)
	}
}


================================================
FILE: internal/analysis/driverutil/print.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package driverutil

// This file defined output helpers common to all drivers.

import (
	"cmp"
	"encoding/json"
	"fmt"
	"go/token"
	"io"
	"log"
	"os"
	"strings"

	"golang.org/x/tools/go/analysis"
)

// TODO(adonovan): don't accept an io.Writer if we don't report errors.
// Either accept a bytes.Buffer (infallible), or return a []byte.

// PrintPlain prints a diagnostic in plain text form.
// If contextLines is nonnegative, it also prints the
// offending line plus this many lines of context.
func PrintPlain(out io.Writer, fset *token.FileSet, contextLines int, diag analysis.Diagnostic) {
	print := func(pos, end token.Pos, message string) {
		posn := fset.Position(pos)
		fmt.Fprintf(out, "%s: %s\n", posn, message)

		// show offending line plus N lines of context.
		if contextLines >= 0 {
			end := fset.Position(end)
			if !end.IsValid() {
				end = posn
			}
			// TODO(adonovan): highlight the portion of the line indicated
			// by pos...end using ASCII art, terminal colors, etc?
			data, _ := os.ReadFile(posn.Filename)
			lines := strings.Split(string(data), "\n")
			for i := posn.Line - contextLines; i <= end.Line+contextLines; i++ {
				if 1 <= i && i <= len(lines) {
					fmt.Fprintf(out, "%d\t%s\n", i, lines[i-1])
				}
			}
		}
	}

	print(diag.Pos, diag.End, diag.Message)
	for _, rel := range diag.Related {
		print(rel.Pos, rel.End, "\t"+rel.Message)
	}
}

// A JSONTree is a mapping from package ID to analysis name to result.
// Each result is either a jsonError or a list of JSONDiagnostic.
type JSONTree map[string]map[string]any

// A TextEdit describes the replacement of a portion of a file.
// Start and End are zero-based half-open indices into the original byte
// sequence of the file, and New is the new text.
type JSONTextEdit struct {
	Filename string `json:"filename"`
	Start    int    `json:"start"`
	End      int    `json:"end"`
	New      string `json:"new"`
}

// A JSONSuggestedFix describes an edit that should be applied as a whole or not
// at all. It might contain multiple TextEdits/text_edits if the SuggestedFix
// consists of multiple non-contiguous edits.
type JSONSuggestedFix struct {
	Message string         `json:"message"`
	Edits   []JSONTextEdit `json:"edits"`
}

// A JSONDiagnostic describes the JSON schema of an analysis.Diagnostic.
type JSONDiagnostic struct {
	Category       string                   `json:"category,omitempty"`
	Posn           string                   `json:"posn"` // e.g. "file.go:line:column"
	End            string                   `json:"end"`  // (ditto)
	Message        string                   `json:"message"`
	SuggestedFixes []JSONSuggestedFix       `json:"suggested_fixes,omitempty"`
	Related        []JSONRelatedInformation `json:"related,omitempty"`
}

// A JSONRelated describes a secondary position and message related to
// a primary diagnostic.
type JSONRelatedInformation struct {
	Posn    string `json:"posn"` // e.g. "file.go:line:column"
	End     string `json:"end"`  // (ditto)
	Message string `json:"message"`
}

// Add adds the result of analysis 'name' on package 'id'.
// The result is either a list of diagnostics or an error.
func (tree JSONTree) Add(fset *token.FileSet, id, name string, diags []analysis.Diagnostic, err error) {
	var v any
	if err != nil {
		type jsonError struct {
			Err string `json:"error"`
		}
		v = jsonError{err.Error()}
	} else if len(diags) > 0 {
		diagnostics := make([]JSONDiagnostic, 0, len(diags))
		for _, f := range diags {
			var fixes []JSONSuggestedFix
			for _, fix := range f.SuggestedFixes {
				var edits []JSONTextEdit
				for _, edit := range fix.TextEdits {
					edits = append(edits, JSONTextEdit{
						Filename: fset.Position(edit.Pos).Filename,
						Start:    fset.Position(edit.Pos).Offset,
						End:      fset.Position(edit.End).Offset,
						New:      string(edit.NewText),
					})
				}
				fixes = append(fixes, JSONSuggestedFix{
					Message: fix.Message,
					Edits:   edits,
				})
			}
			var related []JSONRelatedInformation
			for _, r := range f.Related {
				related = append(related, JSONRelatedInformation{
					Posn:    fset.Position(r.Pos).String(),
					End:     fset.Position(cmp.Or(r.End, r.Pos)).String(),
					Message: r.Message,
				})
			}
			jdiag := JSONDiagnostic{
				Category:       f.Category,
				Posn:           fset.Position(f.Pos).String(),
				End:            fset.Position(cmp.Or(f.End, f.Pos)).String(),
				Message:        f.Message,
				SuggestedFixes: fixes,
				Related:        related,
			}
			diagnostics = append(diagnostics, jdiag)
		}
		v = diagnostics
	}
	if v != nil {
		m, ok := tree[id]
		if !ok {
			m = make(map[string]any)
			tree[id] = m
		}
		m[name] = v
	}
}

func (tree JSONTree) Print(out io.Writer) error {
	data, err := json.MarshalIndent(tree, "", "\t")
	if err != nil {
		log.Panicf("internal error: JSON marshaling failed: %v", err)
	}
	_, err = fmt.Fprintf(out, "%s\n", data)
	return err
}


================================================
FILE: internal/analysis/driverutil/readfile.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package driverutil

// This file defines helpers for implementing [analysis.Pass.ReadFile].

import (
	"fmt"
	"slices"

	"golang.org/x/tools/go/analysis"
)

// A ReadFileFunc is a function that returns the
// contents of a file, such as [os.ReadFile].
type ReadFileFunc = func(filename string) ([]byte, error)

// CheckedReadFile returns a wrapper around a Pass.ReadFile
// function that performs the appropriate checks.
func CheckedReadFile(pass *analysis.Pass, readFile ReadFileFunc) ReadFileFunc {
	return func(filename string) ([]byte, error) {
		if err := CheckReadable(pass, filename); err != nil {
			return nil, err
		}
		return readFile(filename)
	}
}

// CheckReadable enforces the access policy defined by the ReadFile field of [analysis.Pass].
func CheckReadable(pass *analysis.Pass, filename string) error {
	if slices.Contains(pass.OtherFiles, filename) ||
		slices.Contains(pass.IgnoredFiles, filename) {
		return nil
	}
	for _, f := range pass.Files {
		if pass.Fset.File(f.FileStart).Name() == filename {
			return nil
		}
	}
	return fmt.Errorf("Pass.ReadFile: %s is not among OtherFiles, IgnoredFiles, or names of Files", filename)
}


================================================
FILE: internal/analysis/driverutil/url.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package driverutil

import (
	"fmt"
	"net/url"

	"golang.org/x/tools/go/analysis"
)

// ResolveURL resolves the URL field for a Diagnostic from an Analyzer
// and returns the URL. See Diagnostic.URL for details.
func ResolveURL(a *analysis.Analyzer, d analysis.Diagnostic) (string, error) {
	if d.URL == "" && d.Category == "" && a.URL == "" {
		return "", nil // do nothing
	}
	raw := d.URL
	if d.URL == "" && d.Category != "" {
		raw = "#" + d.Category
	}
	u, err := url.Parse(raw)
	if err != nil {
		return "", fmt.Errorf("invalid Diagnostic.URL %q: %s", raw, err)
	}
	base, err := url.Parse(a.URL)
	if err != nil {
		return "", fmt.Errorf("invalid Analyzer.URL %q: %s", a.URL, err)
	}
	return base.ResolveReference(u).String(), nil
}


================================================
FILE: internal/analysis/driverutil/url_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package driverutil_test

import (
	"fmt"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/internal/analysis/driverutil"
)

func TestResolveURLs(t *testing.T) {
	// TestResolveURL test the 12 different combinations for how URLs can be resolved
	// when Analyzer.URL are Diagnostic.Category are empty or non-empty, and when
	// Diagnostic.URL is empty, absolute or relative.

	aURL := &analysis.Analyzer{URL: "https://analyzer.example"}
	noURL := &analysis.Analyzer{URL: ""}
	tests := []struct {
		analyzer   *analysis.Analyzer
		diagnostic analysis.Diagnostic
		want       string
	}{
		{noURL, analysis.Diagnostic{Category: "", URL: ""}, ""},
		{noURL, analysis.Diagnostic{Category: "", URL: "#relative"}, "#relative"},
		{noURL, analysis.Diagnostic{Category: "", URL: "https://absolute.diagnostic"}, "https://absolute.diagnostic"},
		{noURL, analysis.Diagnostic{Category: "category", URL: ""}, "#category"},
		{noURL, analysis.Diagnostic{Category: "category", URL: "#relative"}, "#relative"},
		{noURL, analysis.Diagnostic{Category: "category", URL: "https://absolute.diagnostic"}, "https://absolute.diagnostic"},
		{aURL, analysis.Diagnostic{Category: "", URL: ""}, "https://analyzer.example"},
		{aURL, analysis.Diagnostic{Category: "", URL: "#relative"}, "https://analyzer.example#relative"},
		{aURL, analysis.Diagnostic{Category: "", URL: "https://absolute.diagnostic"}, "https://absolute.diagnostic"},
		{aURL, analysis.Diagnostic{Category: "category", URL: ""}, "https://analyzer.example#category"},
		{aURL, analysis.Diagnostic{Category: "category", URL: "#relative"}, "https://analyzer.example#relative"},
		{aURL, analysis.Diagnostic{Category: "category", URL: "https://absolute.diagnostic"}, "https://absolute.diagnostic"},
	}
	for _, c := range tests {
		got, err := driverutil.ResolveURL(c.analyzer, c.diagnostic)
		if err != nil {
			t.Errorf("Unexpected error from ResolveURL %s", err)
		} else if got != c.want {
			t.Errorf("ResolveURL(%q,%v)=%q. want %s", c.analyzer.URL, c.diagnostic, got, c.want)
		}
	}
}

func TestResolveURLErrors(t *testing.T) {
	tests := []struct {
		analyzer   *analysis.Analyzer
		diagnostic analysis.Diagnostic
		want       string
	}{
		{&analysis.Analyzer{URL: ":not a url"}, analysis.Diagnostic{Category: "", URL: "#relative"}, "invalid Analyzer.URL"},
		{&analysis.Analyzer{URL: "https://analyzer.example"}, analysis.Diagnostic{Category: "", URL: ":not a URL"}, "invalid Diagnostic.URL"},
	}
	for _, c := range tests {
		_, err := driverutil.ResolveURL(c.analyzer, c.diagnostic)
		if got := fmt.Sprint(err); !strings.HasPrefix(got, c.want) {
			t.Errorf("ResolveURL(%q, %q) expected an error starting with %q. got %q", c.analyzer.URL, c.diagnostic.URL, c.want, got)
		}
	}
}


================================================
FILE: internal/analysis/driverutil/validatefix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package driverutil

// This file defines the validation of SuggestedFixes.

import (
	"cmp"
	"fmt"
	"go/token"
	"slices"

	"golang.org/x/tools/go/analysis"
)

// ValidateFixes validates the set of fixes for a single diagnostic.
// Any error indicates a bug in the originating analyzer.
//
// It updates fixes so that fixes[*].End.IsValid().
//
// It may be used as part of an analysis driver implementation.
func ValidateFixes(fset *token.FileSet, a *analysis.Analyzer, fixes []analysis.SuggestedFix) error {
	fixMessages := make(map[string]bool)
	for i := range fixes {
		fix := &fixes[i]
		if fixMessages[fix.Message] {
			return fmt.Errorf("analyzer %q suggests two fixes with same Message (%s)", a.Name, fix.Message)
		}
		fixMessages[fix.Message] = true
		if err := validateFix(fset, fix); err != nil {
			return fmt.Errorf("analyzer %q suggests invalid fix (%s): %v", a.Name, fix.Message, err)
		}
	}
	return nil
}

// validateFix validates a single fix.
// Any error indicates a bug in the originating analyzer.
//
// It updates fix so that fix.End.IsValid().
func validateFix(fset *token.FileSet, fix *analysis.SuggestedFix) error {

	// Stably sort edits by Pos. This ordering puts insertions
	// (end = start) before deletions (end > start) at the same
	// point, but uses a stable sort to preserve the order of
	// multiple insertions at the same point.
	slices.SortStableFunc(fix.TextEdits, func(x, y analysis.TextEdit) int {
		if sign := cmp.Compare(x.Pos, y.Pos); sign != 0 {
			return sign
		}
		return cmp.Compare(x.End, y.End)
	})

	var prev *analysis.TextEdit
	for i := range fix.TextEdits {
		edit := &fix.TextEdits[i]

		// Validate edit individually.
		start := edit.Pos
		file := fset.File(start)
		if file == nil {
			return fmt.Errorf("no token.File for TextEdit.Pos (%v)", edit.Pos)
		}
		fileEnd := token.Pos(file.Base() + file.Size())
		if end := edit.End; end.IsValid() {
			if end < start {
				return fmt.Errorf("TextEdit.Pos (%v) > TextEdit.End (%v)", edit.Pos, edit.End)
			}
			endFile := fset.File(end)
			if endFile != file && end < fileEnd+10 {
				// Relax the checks below in the special case when the end position
				// is only slightly beyond EOF, as happens when End is computed
				// (as in ast.{Struct,Interface}Type) rather than based on
				// actual token positions. In such cases, truncate end to EOF.
				//
				// This is a workaround for #71659; see:
				// https://github.com/golang/go/issues/71659#issuecomment-2651606031
				// A better fix would be more faithful recording of token
				// positions (or their absence) in the AST.
				edit.End = fileEnd
				continue
			}
			if endFile == nil {
				return fmt.Errorf("no token.File for TextEdit.End (%v; File(start).FileEnd is %d)", end, file.Base()+file.Size())
			}
			if endFile != file {
				return fmt.Errorf("edit #%d spans files (%v and %v)",
					i, file.Position(edit.Pos), endFile.Position(edit.End))
			}
		} else {
			edit.End = start // update the SuggestedFix
		}
		if eof := fileEnd; edit.End > eof {
			return fmt.Errorf("end is (%v) beyond end of file (%v)", edit.End, eof)
		}

		// Validate the sequence of edits:
		// properly ordered, no overlapping deletions
		if prev != nil && edit.Pos < prev.End {
			xpos := fset.Position(prev.Pos)
			xend := fset.Position(prev.End)
			ypos := fset.Position(edit.Pos)
			yend := fset.Position(edit.End)
			return fmt.Errorf("overlapping edits to %s (%d:%d-%d:%d and %d:%d-%d:%d)",
				xpos.Filename,
				xpos.Line, xpos.Column,
				xend.Line, xend.Column,
				ypos.Line, ypos.Column,
				yend.Line, yend.Column,
			)
		}
		prev = edit
	}

	return nil
}


================================================
FILE: internal/analysis/generated/generated.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package generated defines an analyzer whose result makes it
// convenient to skip diagnostics within generated files.
package generated

import (
	"go/ast"
	"go/token"
	"reflect"

	"golang.org/x/tools/go/analysis"
)

var Analyzer = &analysis.Analyzer{
	Name:       "generated",
	Doc:        "detect which Go files are generated",
	URL:        "https://pkg.go.dev/golang.org/x/tools/internal/analysis/generated",
	ResultType: reflect.TypeFor[*Result](),
	Run: func(pass *analysis.Pass) (any, error) {
		set := make(map[*token.File]bool)
		for _, file := range pass.Files {
			if ast.IsGenerated(file) {
				set[pass.Fset.File(file.FileStart)] = true
			}
		}
		return &Result{fset: pass.Fset, generatedFiles: set}, nil
	},
}

type Result struct {
	fset           *token.FileSet
	generatedFiles map[*token.File]bool
}

// IsGenerated reports whether the position is within a generated file.
func (r *Result) IsGenerated(pos token.Pos) bool {
	return r.generatedFiles[r.fset.File(pos)]
}


================================================
FILE: internal/analysis/typeindex/typeindex.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typeindex defines an analyzer that provides a
// [golang.org/x/tools/internal/typesinternal/typeindex.Index].
//
// Like [golang.org/x/tools/go/analysis/passes/inspect], it is
// intended to be used as a helper by other analyzers; it reports no
// diagnostics of its own.
package typeindex

import (
	"reflect"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/passes/inspect"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

var Analyzer = &analysis.Analyzer{
	Name: "typeindex",
	Doc:  "indexes of type information for later passes",
	URL:  "https://pkg.go.dev/golang.org/x/tools/internal/analysis/typeindex",
	Run: func(pass *analysis.Pass) (any, error) {
		inspect := pass.ResultOf[inspect.Analyzer].(*inspector.Inspector)
		return typeindex.New(inspect, pass.Pkg, pass.TypesInfo), nil
	},
	RunDespiteErrors: true,
	Requires:         []*analysis.Analyzer{inspect.Analyzer},
	ResultType:       reflect.TypeFor[*typeindex.Index](),
}


================================================
FILE: internal/astutil/clone.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"go/ast"
	"reflect"
)

// CloneNode returns a deep copy of a Node.
// It omits pointers to ast.{Scope,Object} variables.
func CloneNode[T ast.Node](n T) T {
	return cloneNode(n).(T)
}

func cloneNode(n ast.Node) ast.Node {
	var clone func(x reflect.Value) reflect.Value
	set := func(dst, src reflect.Value) {
		src = clone(src)
		if src.IsValid() {
			dst.Set(src)
		}
	}
	clone = func(x reflect.Value) reflect.Value {
		switch x.Kind() {
		case reflect.Pointer:
			if x.IsNil() {
				return x
			}
			// Skip fields of types potentially involved in cycles.
			switch x.Interface().(type) {
			case *ast.Object, *ast.Scope:
				return reflect.Zero(x.Type())
			}
			y := reflect.New(x.Type().Elem())
			set(y.Elem(), x.Elem())
			return y

		case reflect.Struct:
			y := reflect.New(x.Type()).Elem()
			for i := 0; i < x.Type().NumField(); i++ {
				set(y.Field(i), x.Field(i))
			}
			return y

		case reflect.Slice:
			if x.IsNil() {
				return x
			}
			y := reflect.MakeSlice(x.Type(), x.Len(), x.Cap())
			for i := 0; i < x.Len(); i++ {
				set(y.Index(i), x.Index(i))
			}
			return y

		case reflect.Interface:
			y := reflect.New(x.Type()).Elem()
			set(y, x.Elem())
			return y

		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.UnsafePointer:
			panic(x) // unreachable in AST

		default:
			return x // bool, string, number
		}
	}
	return clone(reflect.ValueOf(n)).Interface().(ast.Node)
}


================================================
FILE: internal/astutil/comment.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"go/ast"
	"go/token"
	"iter"
	"strings"
)

// Deprecation returns the paragraph of the doc comment that starts with the
// conventional "Deprecation: " marker, as defined by
// https://go.dev/wiki/Deprecated, or "" if the documented symbol is not
// deprecated.
func Deprecation(doc *ast.CommentGroup) string {
	for p := range strings.SplitSeq(doc.Text(), "\n\n") {
		// There is still some ambiguity for deprecation message. This function
		// only returns the paragraph introduced by "Deprecated: ". More
		// information related to the deprecation may follow in additional
		// paragraphs, but the deprecation message should be able to stand on
		// its own. See golang/go#38743.
		if strings.HasPrefix(p, "Deprecated: ") {
			return p
		}
	}
	return ""
}

// -- plundered from the future (CL 605517, issue #68021) --

// TODO(adonovan): replace with ast.Directive in go1.26 (#68021).
// Beware of our local mods to handle analysistest
// "want" comments on the same line.

// A directive is a comment line with special meaning to the Go
// toolchain or another tool. It has the form:
//
//	//tool:name args
//
// The "tool:" portion is missing for the three directives named
// line, extern, and export.
//
// See https://go.dev/doc/comment#Syntax for details of Go comment
// syntax and https://pkg.go.dev/cmd/compile#hdr-Compiler_Directives
// for details of directives used by the Go compiler.
type Directive struct {
	Pos  token.Pos // of preceding "//"
	Tool string
	Name string
	Args string // may contain internal spaces
}

// isDirective reports whether c is a comment directive.
// This code is also in go/printer.
func isDirective(c string) bool {
	// "//line " is a line directive.
	// "//extern " is for gccgo.
	// "//export " is for cgo.
	// (The // has been removed.)
	if strings.HasPrefix(c, "line ") || strings.HasPrefix(c, "extern ") || strings.HasPrefix(c, "export ") {
		return true
	}

	// "//[a-z0-9]+:[a-z0-9]"
	// (The // has been removed.)
	colon := strings.Index(c, ":")
	if colon <= 0 || colon+1 >= len(c) {
		return false
	}
	for i := 0; i <= colon+1; i++ {
		if i == colon {
			continue
		}
		b := c[i]
		if !('a' <= b && b <= 'z' || '0' <= b && b <= '9') {
			return false
		}
	}
	return true
}

// Directives returns the directives within the comment.
func Directives(g *ast.CommentGroup) (res []*Directive) {
	if g != nil {
		// Avoid (*ast.CommentGroup).Text() as it swallows directives.
		for _, c := range g.List {
			if len(c.Text) > 2 &&
				c.Text[1] == '/' &&
				c.Text[2] != ' ' &&
				isDirective(c.Text[2:]) {

				tool, nameargs, ok := strings.Cut(c.Text[2:], ":")
				if !ok {
					// Must be one of {line,extern,export}.
					tool, nameargs = "", tool
				}
				name, args, _ := strings.Cut(nameargs, " ") // tab??
				// Permit an additional line comment after the args, chiefly to support
				// [golang.org/x/tools/go/analysis/analysistest].
				args, _, _ = strings.Cut(args, "//")
				res = append(res, &Directive{
					Pos:  c.Slash,
					Tool: tool,
					Name: name,
					Args: strings.TrimSpace(args),
				})
			}
		}
	}
	return
}

// Comments returns an iterator over the comments overlapping the specified interval.
func Comments(file *ast.File, start, end token.Pos) iter.Seq[*ast.Comment] {
	// TODO(adonovan): optimize use binary O(log n) instead of linear O(n) search.
	return func(yield func(*ast.Comment) bool) {
		for _, cg := range file.Comments {
			for _, co := range cg.List {
				if co.Pos() > end {
					return
				}
				if co.End() < start {
					continue
				}

				if !yield(co) {
					return
				}
			}
		}
	}
}


================================================
FILE: internal/astutil/comment_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"slices"
	"testing"

	"golang.org/x/tools/internal/astutil"
)

func TestComments(t *testing.T) {
	src := `
package main

// A
func fn() { }`
	var fset token.FileSet
	f, err := parser.ParseFile(&fset, "", []byte(src), parser.ParseComments|parser.AllErrors)
	if err != nil {
		t.Fatal(err)
	}

	commentA := f.Comments[0].List[0]
	commentAMidPos := (commentA.Pos() + commentA.End()) / 2

	want := []*ast.Comment{commentA}
	testCases := []struct {
		name       string
		start, end token.Pos
		want       []*ast.Comment
	}{
		{name: "comment totally overlaps with given interval", start: f.Pos(), end: f.End(), want: want},
		{name: "interval from file start to mid of comment A", start: f.Pos(), end: commentAMidPos, want: want},
		{name: "interval from mid of comment A to file end", start: commentAMidPos, end: commentA.End(), want: want},
		{name: "interval from start of comment A to mid of comment A", start: commentA.Pos(), end: commentAMidPos, want: want},
		{name: "interval from mid of comment A to comment A end", start: commentAMidPos, end: commentA.End(), want: want},
		{name: "interval at the start of comment A", start: commentA.Pos(), end: commentA.Pos(), want: want},
		{name: "interval at the end of comment A", start: commentA.End(), end: commentA.End(), want: want},
		{name: "interval from file start to the front of comment A start", start: f.Pos(), end: commentA.Pos() - 1, want: nil},
		{name: "interval from the position after end of comment A to file end", start: commentA.End() + 1, end: f.End(), want: nil},
	}
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			var got []*ast.Comment
			for co := range astutil.Comments(f, tc.start, tc.end) {
				got = append(got, co)
			}
			if !slices.Equal(got, tc.want) {
				t.Errorf("%s: got %v, want %v", tc.name, got, tc.want)
			}
		})
	}
}


================================================
FILE: internal/astutil/equal.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"go/ast"
	"go/token"
	"reflect"
)

// Equal reports whether two nodes are structurally equal,
// ignoring fields of type [token.Pos], [ast.Object],
// and [ast.Scope], and comments.
//
// The operands x and y may be nil.
// A nil slice is not equal to an empty slice.
//
// The provided function determines whether two identifiers
// should be considered identical.
func Equal(x, y ast.Node, identical func(x, y *ast.Ident) bool) bool {
	if x == nil || y == nil {
		return x == y
	}
	return equal(reflect.ValueOf(x), reflect.ValueOf(y), identical)
}

// EqualSyntax reports whether x and y are equal.
// Identifiers are considered equal if they are spelled the same.
// Comments are ignored.
func EqualSyntax(x, y ast.Expr) bool {
	sameName := func(x, y *ast.Ident) bool { return x.Name == y.Name }
	return Equal(x, y, sameName)
}

func equal(x, y reflect.Value, identical func(x, y *ast.Ident) bool) bool {
	// Ensure types are the same
	if x.Type() != y.Type() {
		return false
	}
	switch x.Kind() {
	case reflect.Pointer:
		if x.IsNil() || y.IsNil() {
			return x.IsNil() == y.IsNil()
		}
		switch t := x.Interface().(type) {
		// Skip fields of types potentially involved in cycles.
		case *ast.Object, *ast.Scope, *ast.CommentGroup:
			return true
		case *ast.Ident:
			return identical(t, y.Interface().(*ast.Ident))
		default:
			return equal(x.Elem(), y.Elem(), identical)
		}

	case reflect.Interface:
		if x.IsNil() || y.IsNil() {
			return x.IsNil() == y.IsNil()
		}
		return equal(x.Elem(), y.Elem(), identical)

	case reflect.Struct:
		for i := range x.NumField() {
			xf := x.Field(i)
			yf := y.Field(i)
			// Skip position fields.
			if xpos, ok := xf.Interface().(token.Pos); ok {
				ypos := yf.Interface().(token.Pos)
				// Numeric value of a Pos is not significant but its "zeroness" is,
				// because it is often significant, e.g. CallExpr.Variadic(Ellipsis), ChanType.Arrow.
				if xpos.IsValid() != ypos.IsValid() {
					return false
				}
			} else if !equal(xf, yf, identical) {
				return false
			}
		}
		return true

	case reflect.Slice:
		if x.IsNil() || y.IsNil() {
			return x.IsNil() == y.IsNil()
		}
		if x.Len() != y.Len() {
			return false
		}
		for i := range x.Len() {
			if !equal(x.Index(i), y.Index(i), identical) {
				return false
			}
		}
		return true

	case reflect.String:
		return x.String() == y.String()

	case reflect.Bool:
		return x.Bool() == y.Bool()

	case reflect.Int:
		return x.Int() == y.Int()

	default:
		panic(x)
	}
}


================================================
FILE: internal/astutil/fields.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"go/ast"
	"iter"
)

// FlatFields 'flattens' an ast.FieldList, returning an iterator over each
// (name, field) combination in the list. For unnamed fields, the identifier is
// nil.
func FlatFields(list *ast.FieldList) iter.Seq2[*ast.Ident, *ast.Field] {
	return func(yield func(*ast.Ident, *ast.Field) bool) {
		if list == nil {
			return
		}

		for _, field := range list.List {
			if len(field.Names) == 0 {
				if !yield(nil, field) {
					return
				}
			} else {
				for _, name := range field.Names {
					if !yield(name, field) {
						return
					}
				}
			}
		}
	}
}


================================================
FILE: internal/astutil/fields_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package astutil_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/astutil"
)

func TestFlatFields(t *testing.T) {
	tests := []struct {
		params string
		want   string
	}{
		{"", ""},
		{"a int", "a int"},
		{"int", "int"},
		{"a, b int", "a int, b int"},
		{"a, b, c int", "a int, b int, c int"},
		{"int, string", "int, string"},
		{"_ int, b string", "_ int, b string"},
		{"a, _ int, b string", "a int, _ int, b string"},
	}

	for _, test := range tests {
		src := fmt.Sprintf("package p; func _(%s)", test.params)
		f, err := parser.ParseFile(token.NewFileSet(), "", src, 0)
		if err != nil {
			t.Fatal(err)
		}
		params := f.Decls[0].(*ast.FuncDecl).Type.Params
		var got bytes.Buffer
		for name, field := range astutil.FlatFields(params) {
			if got.Len() > 0 {
				got.WriteString(", ")
			}
			if name != nil {
				fmt.Fprintf(&got, "%s ", name.Name)
			}
			got.WriteString(types.ExprString(field.Type))
		}
		if got := got.String(); got != test.want {
			// align 'got' and 'want' for easier inspection
			t.Errorf("FlatFields(%q):\n got: %q\nwant: %q", test.params, got, test.want)
		}
	}
}


================================================
FILE: internal/astutil/free/free.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package free defines utilities for computing the free variables of
// a syntax tree without type information. This is inherently
// heuristic because of the T{f: x} ambiguity, in which f may or may
// not be a lexical reference depending on whether T is a struct type.
package free

import (
	"go/ast"
	"go/token"
)

// Copied, with considerable changes, from go/parser/resolver.go
// at af53bd2c03.

// Names computes an approximation to the set of free names of the AST
// at node n based solely on syntax.
//
// In the absence of composite literals, the set of free names is exact. Composite
// literals introduce an ambiguity that can only be resolved with type information:
// whether F is a field name or a value in `T{F: ...}`.
// If includeComplitIdents is true, this function conservatively assumes
// T is not a struct type, so freeishNames overapproximates: the resulting
// set may contain spurious entries that are not free lexical references
// but are references to struct fields.
// If includeComplitIdents is false, this function assumes that T *is*
// a struct type, so freeishNames underapproximates: the resulting set
// may omit names that are free lexical references.
//
// TODO(adonovan): includeComplitIdents is a crude hammer: the caller
// may have partial or heuristic information about whether a given T
// is struct type. Replace includeComplitIdents with a hook to query
// the caller.
//
// The code is based on go/parser.resolveFile, but heavily simplified. Crucial
// differences are:
//   - Instead of resolving names to their objects, this function merely records
//     whether they are free.
//   - Labels are ignored: they do not refer to values.
//   - This is never called on ImportSpecs, so the function panics if it sees one.
func Names(n ast.Node, includeComplitIdents bool) map[string]bool {
	v := &freeVisitor{
		free:                 make(map[string]bool),
		includeComplitIdents: includeComplitIdents,
	}
	// Begin with a scope, even though n might not be a form that establishes a scope.
	// For example, n might be:
	//    x := ...
	// Then we need to add the first x to some scope.
	v.openScope()
	ast.Walk(v, n)
	v.closeScope()
	if v.scope != nil {
		panic("unbalanced scopes")
	}
	return v.free
}

// A freeVisitor holds state for a free-name analysis.
type freeVisitor struct {
	scope                *scope          // the current innermost scope
	free                 map[string]bool // free names seen so far
	includeComplitIdents bool            // include identifier key in composite literals
}

// scope contains all the names defined in a lexical scope.
// It is like ast.Scope, but without deprecation warnings.
type scope struct {
	names map[string]bool
	outer *scope
}

func (s *scope) defined(name string) bool {
	for ; s != nil; s = s.outer {
		if s.names[name] {
			return true
		}
	}
	return false
}

func (v *freeVisitor) Visit(n ast.Node) ast.Visitor {
	switch n := n.(type) {

	// Expressions.
	case *ast.Ident:
		v.use(n)

	case *ast.FuncLit:
		v.openScope()
		defer v.closeScope()
		v.walkFuncType(nil, n.Type)
		v.walkBody(n.Body)

	case *ast.SelectorExpr:
		v.walk(n.X)
		// Skip n.Sel: it cannot be free.

	case *ast.StructType:
		v.openScope()
		defer v.closeScope()
		v.walkFieldList(n.Fields)

	case *ast.FuncType:
		v.openScope()
		defer v.closeScope()
		v.walkFuncType(nil, n)

	case *ast.CompositeLit:
		v.walk(n.Type)
		for _, e := range n.Elts {
			if kv, _ := e.(*ast.KeyValueExpr); kv != nil {
				if ident, _ := kv.Key.(*ast.Ident); ident != nil {
					// It is not possible from syntax alone to know whether
					// an identifier used as a composite literal key is
					// a struct field (if n.Type is a struct) or a value
					// (if n.Type is a map, slice or array).
					if v.includeComplitIdents {
						// Over-approximate by treating both cases as potentially
						// free names.
						v.use(ident)
					} else {
						// Under-approximate by ignoring potentially free names.
					}
				} else {
					v.walk(kv.Key)
				}
				v.walk(kv.Value)
			} else {
				v.walk(e)
			}
		}

	case *ast.InterfaceType:
		v.openScope()
		defer v.closeScope()
		v.walkFieldList(n.Methods)

	// Statements
	case *ast.AssignStmt:
		walkSlice(v, n.Rhs)
		if n.Tok == token.DEFINE {
			v.shortVarDecl(n.Lhs)
		} else {
			walkSlice(v, n.Lhs)
		}

	case *ast.LabeledStmt:
		// Ignore labels.
		v.walk(n.Stmt)

	case *ast.BranchStmt:
		// Ignore labels.

	case *ast.BlockStmt:
		v.openScope()
		defer v.closeScope()
		walkSlice(v, n.List)

	case *ast.IfStmt:
		v.openScope()
		defer v.closeScope()
		v.walk(n.Init)
		v.walk(n.Cond)
		v.walk(n.Body)
		v.walk(n.Else)

	case *ast.CaseClause:
		walkSlice(v, n.List)
		v.openScope()
		defer v.closeScope()
		walkSlice(v, n.Body)

	case *ast.SwitchStmt:
		v.openScope()
		defer v.closeScope()
		v.walk(n.Init)
		v.walk(n.Tag)
		v.walkBody(n.Body)

	case *ast.TypeSwitchStmt:
		v.openScope()
		defer v.closeScope()
		if n.Init != nil {
			v.walk(n.Init)
		}
		v.walk(n.Assign)
		// We can use walkBody here because we don't track label scopes.
		v.walkBody(n.Body)

	case *ast.CommClause:
		v.openScope()
		defer v.closeScope()
		v.walk(n.Comm)
		walkSlice(v, n.Body)

	case *ast.SelectStmt:
		v.walkBody(n.Body)

	case *ast.ForStmt:
		v.openScope()
		defer v.closeScope()
		v.walk(n.Init)
		v.walk(n.Cond)
		v.walk(n.Post)
		v.walk(n.Body)

	case *ast.RangeStmt:
		v.openScope()
		defer v.closeScope()
		v.walk(n.X)
		var lhs []ast.Expr
		if n.Key != nil {
			lhs = append(lhs, n.Key)
		}
		if n.Value != nil {
			lhs = append(lhs, n.Value)
		}
		if len(lhs) > 0 {
			if n.Tok == token.DEFINE {
				v.shortVarDecl(lhs)
			} else {
				walkSlice(v, lhs)
			}
		}
		v.walk(n.Body)

	// Declarations
	case *ast.GenDecl:
		switch n.Tok {
		case token.CONST, token.VAR:
			for _, spec := range n.Specs {
				spec := spec.(*ast.ValueSpec)
				walkSlice(v, spec.Values)
				v.walk(spec.Type)
				v.declare(spec.Names...)
			}

		case token.TYPE:
			for _, spec := range n.Specs {
				spec := spec.(*ast.TypeSpec)
				// Go spec: The scope of a type identifier declared inside a
				// function begins at the identifier in the TypeSpec and ends
				// at the end of the innermost containing block.
				v.declare(spec.Name)
				if spec.TypeParams != nil {
					v.openScope()
					defer v.closeScope()
					v.walkTypeParams(spec.TypeParams)
				}
				v.walk(spec.Type)
			}

		case token.IMPORT:
			panic("encountered import declaration in free analysis")
		}

	case *ast.FuncDecl:
		if n.Recv == nil && n.Name.Name != "init" { // package-level function
			v.declare(n.Name)
		}
		v.openScope()
		defer v.closeScope()
		v.walkTypeParams(n.Type.TypeParams)
		v.walkFuncType(n.Recv, n.Type)
		v.walkBody(n.Body)

	default:
		return v
	}

	return nil
}

func (v *freeVisitor) openScope() {
	v.scope = &scope{map[string]bool{}, v.scope}
}

func (v *freeVisitor) closeScope() {
	v.scope = v.scope.outer
}

func (v *freeVisitor) walk(n ast.Node) {
	if n != nil {
		ast.Walk(v, n)
	}
}

func (v *freeVisitor) walkFuncType(recv *ast.FieldList, typ *ast.FuncType) {
	// First use field types...
	v.walkRecvFieldType(recv)
	v.walkFieldTypes(typ.Params)
	v.walkFieldTypes(typ.Results)

	// ...then declare field names.
	v.declareFieldNames(recv)
	v.declareFieldNames(typ.Params)
	v.declareFieldNames(typ.Results)
}

// A receiver field is not like a param or result field because
// "func (recv R[T]) method()" uses R but declares T.
func (v *freeVisitor) walkRecvFieldType(list *ast.FieldList) {
	if list == nil {
		return
	}
	for _, f := range list.List { // valid => len=1
		typ := f.Type
		if ptr, ok := typ.(*ast.StarExpr); ok {
			typ = ptr.X
		}

		// Analyze receiver type as Base[Index, ...]
		var (
			base    ast.Expr
			indices []ast.Expr
		)
		switch typ := typ.(type) {
		case *ast.IndexExpr: // B[T]
			base, indices = typ.X, []ast.Expr{typ.Index}
		case *ast.IndexListExpr: // B[K, V]
			base, indices = typ.X, typ.Indices
		default: // B
			base = typ
		}
		for _, expr := range indices {
			if id, ok := expr.(*ast.Ident); ok {
				v.declare(id)
			}
		}
		v.walk(base)
	}
}

// walkTypeParams is like walkFieldList, but declares type parameters eagerly so
// that they may be resolved in the constraint expressions held in the field
// Type.
func (v *freeVisitor) walkTypeParams(list *ast.FieldList) {
	v.declareFieldNames(list)
	v.walkFieldTypes(list) // constraints
}

func (v *freeVisitor) walkBody(body *ast.BlockStmt) {
	if body == nil {
		return
	}
	walkSlice(v, body.List)
}

func (v *freeVisitor) walkFieldList(list *ast.FieldList) {
	if list == nil {
		return
	}
	v.walkFieldTypes(list)    // .Type may contain references
	v.declareFieldNames(list) // .Names declares names
}

func (v *freeVisitor) shortVarDecl(lhs []ast.Expr) {
	// Go spec: A short variable declaration may redeclare variables provided
	// they were originally declared in the same block with the same type, and
	// at least one of the non-blank variables is new.
	//
	// However, it doesn't matter to free analysis whether a variable is declared
	// fresh or redeclared.
	for _, x := range lhs {
		// In a well-formed program each expr must be an identifier,
		// but be forgiving.
		if id, ok := x.(*ast.Ident); ok {
			v.declare(id)
		}
	}
}

func walkSlice[S ~[]E, E ast.Node](r *freeVisitor, list S) {
	for _, e := range list {
		r.walk(e)
	}
}

// walkFieldTypes resolves the types of the walkFieldTypes in list.
// The companion method declareFieldList declares the names of the walkFieldTypes.
func (v *freeVisitor) walkFieldTypes(list *ast.FieldList) {
	if list != nil {
		for _, f := range list.List {
			v.walk(f.Type)
		}
	}
}

// declareFieldNames declares the names of the fields in list.
// (Names in a FieldList always establish new bindings.)
// The companion method resolveFieldList resolves the types of the fields.
func (v *freeVisitor) declareFieldNames(list *ast.FieldList) {
	if list != nil {
		for _, f := range list.List {
			v.declare(f.Names...)
		}
	}
}

// use marks ident as free if it is not in scope.
func (v *freeVisitor) use(ident *ast.Ident) {
	if s := ident.Name; s != "_" && !v.scope.defined(s) {
		v.free[s] = true
	}
}

// declare adds each non-blank ident to the current scope.
func (v *freeVisitor) declare(idents ...*ast.Ident) {
	for _, id := range idents {
		if id.Name != "_" {
			v.scope.names[id.Name] = true
		}
	}
}


================================================
FILE: internal/astutil/free/free_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package free_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"maps"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/internal/astutil/free"
)

func TestNames(t *testing.T) {
	elems := func(m map[string]bool) string {
		return strings.Join(slices.Sorted(maps.Keys(m)), " ")
	}

	type testcase struct {
		code string // file content (without package decl)
		want string // space-separated list of expected free names of first decl
	}

	for _, tc := range []struct {
		includeComplitIdents bool
		cases                []testcase
	}{
		{true, []testcase{
			{
				`var _ = x`,
				"x",
			},
			{
				`var _ = x.y.z`,
				"x",
			},
			{
				`var _ = T{a: 1, b: 2, c.d: e}`,
				"a b c e T",
			},
			{
				`var _ = f(x)`,
				"f x",
			},
			{
				`var _ = f.m(x)`,
				"f x",
			},
			{
				`var _ = func(x int) int { return x + y }`,
				"int y",
			},
			{
				`func _() { x = func(x int) int { return 2*x }() }`,
				"int x",
			},
			{
				`var _ = func(x int) (y int) { return x + y }`,
				"int",
			},
			{
				`var _ = struct{a **int; b map[int][]bool}`,
				"bool int",
			},
			{
				`var _ = struct{f int}{f: 0}`,
				"f int",
			},
			{
				`var _ = interface{m1(int) bool; m2(x int) (y bool)}`,
				"bool int",
			},
			{
				`func _() { x := 1; x++ }`,
				"",
			},
			{
				`func _() { x = 1 }`,
				"x",
			},
			{
				`func _() { _ = 1 }`,
				"",
			},
			{
				`func _() { x, y := 1, 2; x = y + z }`,
				"z",
			},
			{
				`func _() { x, y := y, x; x = y + z }`,
				"x y z",
			},
			{
				`func _() { a, b := 0, 0; b, c := 0, 0; print(a, b, c, d) }`,
				"d print",
			},
			{
				`func _() { label: x++ }`,
				"x",
			},
			{
				`func _() { if x == y {x} }`,
				"x y",
			},
			{
				`func _() { if x := 1; x == y {x} }`,
				"y",
			},
			{
				`func _() { if x := 1; x == y {x} else {z} }`,
				"y z",
			},
			{
				`func _() { switch x { case 1: x; case y: z } }`,
				"x y z",
			},
			{
				`func _() { switch x := 1; x { case 1: x; case y: z } }`,
				"y z",
			},
			{
				`func _() { switch x.(type) { case int: x; case []int: y } }`,
				"int x y",
			},
			{
				`func _() { switch x := 1; x.(type) { case int: x; case []int: y } }`,
				"int y",
			},
			{
				`func _() { switch y := x.(type) { case int: x; case []int: y } }`,
				"int x",
			},
			{
				`func _() { select { case c <- 1: x; case x := <-c: 2; default: y} }`,
				"c x y",
			},
			{
				`func _() { for i := 0; i < 9; i++ { c <- j } }`,
				"c j",
			},
			{
				`func _() { for i = 0; i < 9; i++ { c <- j } }`,
				"c i j",
			},
			{
				`func _() { for i := range 9 { c <- j } }`,
				"c j",
			},
			{
				`func _() { for i = range 9 { c <- j } }`,
				"c i j",
			},
			{
				`func _() { for _, e := range []int{1, 2, x} {e} }`,
				"int x",
			},
			{
				`func _() { var x, y int; f(x, y) }`,
				"f int",
			},
			{
				`func _() { {var x, y int}; f(x, y) }`,
				"f int x y",
			},
			{
				`func _() { const x = 1; { const y = iota; return x, y } }`,
				"iota",
			},
			{
				`func _() { type t int; t(0) }`,
				"int",
			},
			{
				`func _() { type t[T ~int] struct { t T };  x = t{t: 1}.t }`, // field t shadowed by type decl
				"int x",
			},
			{
				`func _() { type t[S ~[]E, E any] S }`,
				"any",
			},
			{
				`var a [unsafe.Sizeof(func(x int) { x + y })]int`,
				"int unsafe y",
			},
			{
				`func f(x int) (int y)`,
				"int y",
			},
			{
				`func f(int x) (y int)`,
				"int x",
			},
			{
				`func f[T int](int [k]T) *T`,
				"int k",
			},
			{
				`func f[T *T]([k]T)`,
				"k",
			},
			{
				`func (recv T) method(x int) { print(recv) }`,
				"T int print",
			},
			{
				`func (recv R[P]) method(x int) { var _ P }`,
				"R int",
			},
			{
				`func (recv R[P, P2]) method(x int) { var ( _ P; _ P2 ) }`,
				"R int",
			},
			{
				`func init() { print(init) }`,
				"print init",
			},
		}},
		{
			false,
			[]testcase{
				{
					`func _() { x }`,
					"x",
				},
				{
					`func _() { x.y.z }`,
					"x",
				},
				{
					`func _() { T{a: 1, b: 2, c.d: e} }`,
					"c e T", // omit a and b
				},
				{
					`func _() { type t[T ~int] struct { t T };  x = t{t: 1}.t }`, // field t shadowed by type decl
					"int x",
				},
			},
		},
	} {
		t.Run(fmt.Sprintf("includeComplitIdents=%t", tc.includeComplitIdents), func(t *testing.T) {
			for _, test := range tc.cases {
				_, f := mustParse(t, "free.go", `package p; `+test.code)
				decl := f.Decls[0]
				want := map[string]bool{}
				for name := range strings.FieldsSeq(test.want) {
					want[name] = true
				}

				got := free.Names(decl, tc.includeComplitIdents)

				if !maps.Equal(got, want) {
					t.Errorf("\ncode  %s\ngot   %v\nwant  %v", test.code, elems(got), elems(want))
				}
			}
		})
	}
}

func TestFreeNames_scope(t *testing.T) {
	// Verify that inputs that don't start a scope don't crash.
	_, f := mustParse(t, "free.go", `package p; func _() { x := 1; _ = x }`)
	// Select the short var decl, not the entire function body.
	n := f.Decls[0].(*ast.FuncDecl).Body.List[0]
	_ = free.Names(n, false)
}

func mustParse(t *testing.T, filename string, content any) (*token.FileSet, *ast.File) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, filename, content, parser.ParseComments|parser.SkipObjectResolution)
	if err != nil {
		t.Fatalf("ParseFile: %v\ncode: %s", err, content)
	}
	return fset, f
}


================================================
FILE: internal/astutil/purge.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package astutil provides various AST utility functions for gopls.
package astutil

import (
	"bytes"
	"go/scanner"
	"go/token"
)

// PurgeFuncBodies returns a copy of src in which the contents of each
// outermost {...} region except struct and interface types have been
// deleted. This reduces the amount of work required to parse the
// top-level declarations.
//
// PurgeFuncBodies does not preserve newlines or position information.
// Also, if the input is invalid, parsing the output of
// PurgeFuncBodies may result in a different tree due to its effects
// on parser error recovery.
func PurgeFuncBodies(src []byte) []byte {
	// Destroy the content of any {...}-bracketed regions that are
	// not immediately preceded by a "struct" or "interface"
	// token.  That includes function bodies, composite literals,
	// switch/select bodies, and all blocks of statements.
	// This will lead to non-void functions that don't have return
	// statements, which of course is a type error, but that's ok.

	var out bytes.Buffer
	file := token.NewFileSet().AddFile("", -1, len(src))
	var sc scanner.Scanner
	sc.Init(file, src, nil, 0)
	var prev token.Token
	var cursor int         // last consumed src offset
	var braces []token.Pos // stack of unclosed braces or -1 for struct/interface type
	for {
		pos, tok, _ := sc.Scan()
		if tok == token.EOF {
			break
		}
		switch tok {
		case token.COMMENT:
			// TODO(adonovan): opt: skip, to save an estimated 20% of time.

		case token.LBRACE:
			if prev == token.STRUCT || prev == token.INTERFACE {
				pos = -1
			}
			braces = append(braces, pos)

		case token.RBRACE:
			if last := len(braces) - 1; last >= 0 {
				top := braces[last]
				braces = braces[:last]
				if top < 0 {
					// struct/interface type: leave alone
				} else if len(braces) == 0 { // toplevel only
					// Delete {...} body.
					start := file.Offset(top)
					end := file.Offset(pos)
					out.Write(src[cursor : start+len("{")])
					cursor = end
				}
			}
		}
		prev = tok
	}
	out.Write(src[cursor:])
	return out.Bytes()
}


================================================
FILE: internal/astutil/purge_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"os"
	"reflect"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/testenv"
)

// TestPurgeFuncBodies tests PurgeFuncBodies by comparing it against a
// (less efficient) reference implementation that purges after parsing.
func TestPurgeFuncBodies(t *testing.T) {
	testenv.NeedsGoBuild(t) // we need the source code for std

	// Load a few standard packages.
	config := packages.Config{Mode: packages.NeedCompiledGoFiles}
	pkgs, err := packages.Load(&config, "encoding/...")
	if err != nil {
		t.Fatal(err)
	}

	// preorder returns the nodes of tree f in preorder.
	preorder := func(f *ast.File) (nodes []ast.Node) {
		ast.Inspect(f, func(n ast.Node) bool {
			if n != nil {
				nodes = append(nodes, n)
			}
			return true
		})
		return nodes
	}

	packages.Visit(pkgs, nil, func(p *packages.Package) {
		for _, filename := range p.CompiledGoFiles {
			content, err := os.ReadFile(filename)
			if err != nil {
				t.Fatal(err)
			}

			fset := token.NewFileSet()

			// Parse then purge (reference implementation).
			f1, _ := parser.ParseFile(fset, filename, content, parser.SkipObjectResolution)
			ast.Inspect(f1, func(n ast.Node) bool {
				switch n := n.(type) {
				case *ast.FuncDecl:
					if n.Body != nil {
						n.Body.List = nil
					}
				case *ast.FuncLit:
					n.Body.List = nil
				case *ast.CompositeLit:
					n.Elts = nil
				}
				return true
			})

			// Purge before parse (logic under test).
			f2, _ := parser.ParseFile(fset, filename, astutil.PurgeFuncBodies(content), parser.SkipObjectResolution)

			// Compare sequence of node types.
			nodes1 := preorder(f1)
			nodes2 := preorder(f2)
			if len(nodes2) < len(nodes1) {
				t.Errorf("purged file has fewer nodes: %d vs  %d",
					len(nodes2), len(nodes1))
				nodes1 = nodes1[:len(nodes2)] // truncate
			}
			for i := range nodes1 {
				x, y := nodes1[i], nodes2[i]
				if reflect.TypeOf(x) != reflect.TypeOf(y) {
					t.Errorf("%s: got %T, want %T",
						fset.Position(x.Pos()), y, x)
					break
				}
			}
		}
	})
}


================================================
FILE: internal/astutil/stringlit.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"fmt"
	"go/ast"
	"go/token"
	"strconv"
	"unicode/utf8"
)

// RangeInStringLiteral calculates the positional range within a string literal
// corresponding to the specified start and end byte offsets within the logical string.
func RangeInStringLiteral(lit *ast.BasicLit, start, end int) (Range, error) {
	startPos, err := PosInStringLiteral(lit, start)
	if err != nil {
		return Range{}, fmt.Errorf("start: %v", err)
	}
	endPos, err := PosInStringLiteral(lit, end)
	if err != nil {
		return Range{}, fmt.Errorf("end: %v", err)
	}
	return Range{startPos, endPos}, nil
}

// PosInStringLiteral returns the position within a string literal
// corresponding to the specified byte offset within the logical
// string that it denotes.
func PosInStringLiteral(lit *ast.BasicLit, offset int) (token.Pos, error) {
	raw := lit.Value

	value, err := strconv.Unquote(raw)
	if err != nil {
		return 0, err
	}
	if !(0 <= offset && offset <= len(value)) {
		return 0, fmt.Errorf("invalid offset")
	}

	pos, _ := walkStringLiteral(lit, lit.End(), offset)
	return pos, nil
}

// OffsetInStringLiteral returns the byte offset within the logical (unquoted)
// string corresponding to the specified source position.
func OffsetInStringLiteral(lit *ast.BasicLit, pos token.Pos) (int, error) {
	if !NodeContainsPos(lit, pos) {
		return 0, fmt.Errorf("invalid position")
	}

	raw := lit.Value

	value, err := strconv.Unquote(raw)
	if err != nil {
		return 0, err
	}

	_, offset := walkStringLiteral(lit, pos, len(value))
	return offset, nil
}

// walkStringLiteral iterates through the raw string literal to map between
// a file position and a logical byte offset. It stops when it reaches
// either the targetPos or the targetOffset.
//
// TODO(hxjiang): consider making an iterator.
func walkStringLiteral(lit *ast.BasicLit, targetPos token.Pos, targetOffset int) (token.Pos, int) {
	raw := lit.Value
	norm := int(lit.End()-lit.Pos()) > len(lit.Value)

	// remove quotes
	quote := raw[0] // '"' or '`'
	raw = raw[1 : len(raw)-1]

	var (
		i   = 0             // byte index within logical value
		pos = lit.Pos() + 1 // position within literal
	)

	for raw != "" {
		r, _, rest, _ := strconv.UnquoteChar(raw, quote) // can't fail
		sz := len(raw) - len(rest)                       // length of literal char in raw bytes

		nextPos := pos + token.Pos(sz)
		if norm && r == '\n' {
			nextPos++
		}
		nextI := i + utf8.RuneLen(r) // length of logical char in "cooked" bytes

		if nextPos > targetPos || nextI > targetOffset {
			break
		}

		raw = raw[sz:]
		i = nextI
		pos = nextPos
	}

	return pos, i
}


================================================
FILE: internal/astutil/stringlit_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"strconv"
	"strings"
	"testing"

	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/testenv"
)

func TestPosInStringLiteral(t *testing.T) {
	// Each string is Go source for a string literal with ^ marker at expected Pos.
	tests := []string{
		`"^abc"`,
		`"a^bc"`,
		`"ab^c"`,
		`"abc^"`,
		`"a\n^b"`,
		`"\n^"`,
		`"a\000^"`,
		`"\x61^"`,
		`"\u0061^"`,
		`"\U00000061^"`,
		`"€^"`,
		`"a€^b"`,
		"`abc^`",
		"`a\n^b`",
		// normalization of \r carriage returns:
		"`a\r\n^b`",
		"`a\r\nb\r\nc\r\n^d`",
	}
	for _, test := range tests {
		// The workaround for \r requires the go1.26 fix for https://go.dev/issue/76031.
		if strings.Contains(test, "\r") && testenv.Go1Point() < 26 {
			continue
		}

		t.Logf("input: %#q", test)

		// Parse.
		const prefix = "package p; const _ = "
		src := prefix + test
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "p.go", src, 0)
		if err != nil {
			t.Errorf("Parse: %v", err)
			continue
		}

		// Find literal.
		var lit *ast.BasicLit
		ast.Inspect(f, func(n ast.Node) bool {
			if b, ok := n.(*ast.BasicLit); ok {
				lit = b
				return false
			}
			return true
		})
		if lit == nil {
			t.Errorf("No literal")
			continue
		}

		// Find index of marker within logical value.
		value, err := strconv.Unquote(lit.Value)
		if err != nil {
			t.Errorf("Unquote: %v", err)
			continue
		}
		index := strings.Index(value, "^")
		if index < 0 {
			t.Errorf("Value %q contains no marker", value)
			continue
		}

		// Convert logical index to file position.
		pos, err := astutil.PosInStringLiteral(lit, index)
		if err != nil {
			t.Errorf("PosInStringLiteral(%d): %v", index, err)
			continue
		}

		// Check that cut offset in original src file is before marker.
		offset := fset.Position(pos).Offset
		before, after := src[:offset], src[offset:]
		t.Logf("\t%q :: %q", before, after)
		if !strings.HasPrefix(after, "^") {
			t.Errorf("no marker at cut point")
			continue
		}
	}
}

func TestOffsetInStringLiteral(t *testing.T) {
	// Each string is Go source for a string literal with | marker at expected
	// physical pos, and $ marker at the expected logical unquoted index.
	tests := []string{
		`"$|abc"`,
		`"a$|bc"`,
		`"ab$|c"`,
		`"abc$|"`,
		`"a\n$|b"`,
		`"\n$|"`,
		`"a\000$|"`,
		`"\x61$|"`,
		`"\u0061$|"`,
		`"\U00000061$|"`,
		`"$\U00|000061"`,
		`"€$|"`,
		`"a€$|b"`,
		"`abc$|`",
		"`a\n$|b`",
		// normalization of \r carriage returns:
		"`a\r\n$|b`",
		"`a\r\nb\r\nc\r\n$|d`",
	}
	for _, test := range tests {
		// The workaround for \r requires the go1.26 fix for https://go.dev/issue/76031.
		if strings.Contains(test, "\r") && testenv.Go1Point() < 26 {
			continue
		}

		t.Logf("input: %#q", test)

		const prefix = "package p; const _ = "
		src := prefix + test

		// Remove the physical marker to produce valid Go source.
		offset := strings.Index(src, "|")
		if offset < 0 {
			t.Errorf("Source %q contains no marker", src)
			continue
		}
		src = src[:offset] + src[offset+1:]

		// Parse.
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "p.go", src, 0)
		if err != nil {
			t.Errorf("Parse: %v", err)
			continue
		}

		// Find literal.
		var lit *ast.BasicLit
		ast.Inspect(f, func(n ast.Node) bool {
			if b, ok := n.(*ast.BasicLit); ok {
				lit = b
				return false
			}
			return true
		})
		if lit == nil {
			t.Errorf("No literal")
			continue
		}

		tfile := fset.File(f.Pos())
		pos := tfile.Pos(offset)

		// Convert file position to logical index.
		index, err := astutil.OffsetInStringLiteral(lit, pos)
		if err != nil {
			t.Errorf("OffsetInStringLiteral(%d): %v", pos, err)
			continue
		}

		value, err := strconv.Unquote(lit.Value)
		if err != nil {
			t.Errorf("Unquote: %v", err)
			continue
		}

		if index < 0 || index > len(value) {
			t.Errorf("Returned index %d is out of bounds for logical string of length %d", index, len(value))
			continue
		}

		// Check that cut offset in value is before marker.
		before, after := value[:index], value[index:]
		t.Logf("\t%q :: %q", before, after)
		if !strings.HasSuffix(before, "$") {
			t.Errorf("no marker at logical cut point, got before=%q", before)
			continue
		}
	}
}


================================================
FILE: internal/astutil/unpack.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"go/ast"

	"golang.org/x/tools/internal/typeparams"
)

// UnpackRecv unpacks a receiver type expression, reporting whether it is a
// pointer receiver, along with the type name identifier and any receiver type
// parameter identifiers.
//
// Copied (with modifications) from go/types.
func UnpackRecv(rtyp ast.Expr) (ptr bool, rname *ast.Ident, tparams []*ast.Ident) {
L: // unpack receiver type
	// This accepts invalid receivers such as ***T and does not
	// work for other invalid receivers, but we don't care. The
	// validity of receiver expressions is checked elsewhere.
	for {
		switch t := rtyp.(type) {
		case *ast.ParenExpr:
			rtyp = t.X
		case *ast.StarExpr:
			ptr = true
			rtyp = t.X
		default:
			break L
		}
	}

	// unpack type parameters, if any
	switch rtyp.(type) {
	case *ast.IndexExpr, *ast.IndexListExpr:
		var indices []ast.Expr
		rtyp, _, indices, _ = typeparams.UnpackIndexExpr(rtyp)
		for _, arg := range indices {
			var par *ast.Ident
			switch arg := arg.(type) {
			case *ast.Ident:
				par = arg
			default:
				// ignore errors
			}
			if par == nil {
				par = &ast.Ident{NamePos: arg.Pos(), Name: "_"}
			}
			tparams = append(tparams, par)
		}
	}

	// unpack receiver name
	if name, _ := rtyp.(*ast.Ident); name != nil {
		rname = name
	}

	return
}


================================================
FILE: internal/astutil/util.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package astutil

import (
	"fmt"
	"go/ast"
	"go/printer"
	"go/token"
	"strings"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/moreiters"
)

// NodeContains reports whether the Pos/End range of node n encloses
// the given range.
//
// It is inclusive of both end points, to allow hovering (etc) when
// the cursor is immediately after a node.
//
// Like [NodeRange], it treats the range of an [ast.File] as the
// file's complete extent.
//
// Precondition: n must not be nil.
func NodeContains(n ast.Node, rng Range) bool {
	return NodeRange(n).Contains(rng)
}

// NodeContainsPos reports whether the Pos/End range of node n encloses
// the given pos.
//
// Like [NodeRange], it treats the range of an [ast.File] as the
// file's complete extent.
func NodeContainsPos(n ast.Node, pos token.Pos) bool {
	return NodeRange(n).ContainsPos(pos)
}

// EnclosingFile returns the syntax tree for the file enclosing c.
//
// TODO(adonovan): promote this to a method of Cursor.
func EnclosingFile(c inspector.Cursor) *ast.File {
	c, _ = moreiters.First(c.Enclosing((*ast.File)(nil)))
	return c.Node().(*ast.File)
}

// DocComment returns the doc comment for a node, if any.
func DocComment(n ast.Node) *ast.CommentGroup {
	switch n := n.(type) {
	case *ast.FuncDecl:
		return n.Doc
	case *ast.GenDecl:
		return n.Doc
	case *ast.ValueSpec:
		return n.Doc
	case *ast.TypeSpec:
		return n.Doc
	case *ast.File:
		return n.Doc
	case *ast.ImportSpec:
		return n.Doc
	case *ast.Field:
		return n.Doc
	}
	return nil
}

// Format returns a string representation of the node n.
func Format(fset *token.FileSet, n ast.Node) string {
	var buf strings.Builder
	printer.Fprint(&buf, fset, n) // ignore errors
	return buf.String()
}

// -- Range --

// Range is a Pos interval.
// It implements [analysis.Range] and [ast.Node].
type Range struct{ Start, EndPos token.Pos }

// RangeOf constructs a Range.
//
// RangeOf exists to pacify the "unkeyed literal" (composites) vet
// check. It would be nice if there were a way for a type to add
// itself to the allowlist.
func RangeOf(start, end token.Pos) Range { return Range{start, end} }

// NodeRange returns the extent of node n as a Range.
//
// For unfortunate historical reasons, the Pos/End extent of an
// ast.File runs from the start of its package declaration---excluding
// copyright comments, build tags, and package documentation---to the
// end of its last declaration, excluding any trailing comments. So,
// as a special case, if n is an [ast.File], NodeContains uses
// n.FileStart <= pos && pos <= n.FileEnd to report whether the
// position lies anywhere within the file.
func NodeRange(n ast.Node) Range {
	if file, ok := n.(*ast.File); ok {
		return Range{file.FileStart, file.FileEnd} // entire file
	}
	return Range{n.Pos(), n.End()}
}

func (r Range) Pos() token.Pos { return r.Start }
func (r Range) End() token.Pos { return r.EndPos }

// ContainsPos reports whether the range (inclusive of both end points)
// includes the specified position.
func (r Range) ContainsPos(pos token.Pos) bool {
	return r.Contains(RangeOf(pos, pos))
}

// Contains reports whether the range (inclusive of both end points)
// includes the specified range.
func (r Range) Contains(rng Range) bool {
	return r.Start <= rng.Start && rng.EndPos <= r.EndPos
}

// IsValid reports whether the range is valid.
func (r Range) IsValid() bool { return r.Start.IsValid() && r.Start <= r.EndPos }

// --

// Select returns the syntax nodes identified by a user's text
// selection. It returns three nodes: the innermost node that wholly
// encloses the selection; and the first and last nodes that are
// wholly enclosed by the selection.
//
// For example, given this selection:
//
//	{ f(); g(); /* comment */ }
//	  ~~~~~~~~~~~
//
// Select returns the enclosing BlockStmt, the f() CallExpr, and the g() CallExpr.
//
// If the selection does not wholly enclose any nodes, Select returns an error
// and invalid start/end nodes, but it may return a valid enclosing node.
//
// Callers that require exactly one syntax tree (e.g. just f() or just
// g()) should check that the returned start and end nodes are
// identical.
//
// This function is intended to be called early in the handling of a
// user's request, since it is tolerant of sloppy selection including
// extraneous whitespace and comments. Use it in new code instead of
// PathEnclosingInterval. When the exact extent of a node is known,
// use [Cursor.FindByPos] instead.
func Select(curFile inspector.Cursor, start, end token.Pos) (_enclosing, _start, _end inspector.Cursor, _ error) {
	curEnclosing, ok := curFile.FindByPos(start, end)
	if !ok {
		return noCursor, noCursor, noCursor, fmt.Errorf("invalid selection")
	}

	// Find the first and last node wholly within the (start, end) range.
	// We'll narrow the effective selection to them, to exclude whitespace.
	// (This matches the functionality of PathEnclosingInterval.)
	var curStart, curEnd inspector.Cursor
	rng := RangeOf(start, end)
	for cur := range curEnclosing.Preorder() {
		if rng.Contains(NodeRange(cur.Node())) {
			// The start node has the least Pos.
			if !curStart.Valid() {
				curStart = cur
			}
			// The end node has the greatest End.
			// End positions do not change monotonically,
			// so we must compute the max.
			if !curEnd.Valid() ||
				cur.Node().End() > curEnd.Node().End() {
				curEnd = cur
			}
		}
	}
	if !curStart.Valid() {
		// The selection is valid (inside curEnclosing) but contains no
		// complete nodes. This happens for point selections (start == end),
		// or selections covering only only spaces, comments, and punctuation
		// tokens.
		// Return the enclosing node so the caller can still use the context.
		return curEnclosing, noCursor, noCursor, fmt.Errorf("invalid selection")
	}
	return curEnclosing, curStart, curEnd, nil
}

var noCursor inspector.Cursor

// MaybeParenthesize returns new, possibly wrapped in parens if needed
// to preserve operator precedence when it replaces old, whose parent
// is parentNode.
//
// (This would be more naturally written in terms of Cursor, but one of
// the callers--the inliner--does not have cursors handy.)
func MaybeParenthesize(parentNode ast.Node, old, new ast.Expr) ast.Expr {
	if needsParens(parentNode, old, new) {
		new = &ast.ParenExpr{X: new}
	}
	return new
}

func needsParens(parentNode ast.Node, old, new ast.Expr) bool {
	// An expression beneath a non-expression
	// has no precedence ambiguity.
	parent, ok := parentNode.(ast.Expr)
	if !ok {
		return false
	}

	precedence := func(n ast.Node) int {
		switch n := n.(type) {
		case *ast.UnaryExpr, *ast.StarExpr:
			return token.UnaryPrec
		case *ast.BinaryExpr:
			return n.Op.Precedence()
		}
		return -1
	}

	// Parens are not required if the new node
	// is not unary or binary.
	newprec := precedence(new)
	if newprec < 0 {
		return false
	}

	// Parens are required if parent and child are both
	// unary or binary and the parent has higher precedence.
	if precedence(parent) > newprec {
		return true
	}

	// Was the old node the operand of a postfix operator?
	//  f().sel
	//  f()[i:j]
	//  f()[i]
	//  f().(T)
	//  f()(x)
	switch parent := parent.(type) {
	case *ast.SelectorExpr:
		return parent.X == old
	case *ast.IndexExpr:
		return parent.X == old
	case *ast.SliceExpr:
		return parent.X == old
	case *ast.TypeAssertExpr:
		return parent.X == old
	case *ast.CallExpr:
		return parent.Fun == old
	}
	return false
}


================================================
FILE: internal/bisect/bisect.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package bisect can be used by compilers and other programs
// to serve as a target for the bisect debugging tool.
// See [golang.org/x/tools/cmd/bisect] for details about using the tool.
//
// To be a bisect target, allowing bisect to help determine which of a set of independent
// changes provokes a failure, a program needs to:
//
//  1. Define a way to accept a change pattern on its command line or in its environment.
//     The most common mechanism is a command-line flag.
//     The pattern can be passed to [New] to create a [Matcher], the compiled form of a pattern.
//
//  2. Assign each change a unique ID. One possibility is to use a sequence number,
//     but the most common mechanism is to hash some kind of identifying information
//     like the file and line number where the change might be applied.
//     [Hash] hashes its arguments to compute an ID.
//
//  3. Enable each change that the pattern says should be enabled.
//     The [Matcher.Enable] method answers this question for a given change ID.
//
//  4. Report each change that the pattern says should be reported.
//     The [Matcher.Report] method answers this question for a given change ID.
//     The report consists of one more lines on standard error or standard output
//     that contain a “match marker”. [Marker] returns the match marker for a given ID.
//     When bisect reports a change as causing the failure, it identifies the change
//     by printing those report lines, with the match marker removed.
//
// # Example Usage
//
// A program starts by defining how it receives the pattern. In this example, we will assume a flag.
// The next step is to compile the pattern:
//
//	m, err := bisect.New(patternFlag)
//	if err != nil {
//		log.Fatal(err)
//	}
//
// Then, each time a potential change is considered, the program computes
// a change ID by hashing identifying information (source file and line, in this case)
// and then calls m.ShouldEnable and m.ShouldReport to decide whether to
// enable and report the change, respectively:
//
//	for each change {
//		h := bisect.Hash(file, line)
//		if m.ShouldEnable(h) {
//			enableChange()
//		}
//		if m.ShouldReport(h) {
//			log.Printf("%v %s:%d", bisect.Marker(h), file, line)
//		}
//	}
//
// Note that the two return different values when bisect is searching for a
// minimal set of changes to disable to provoke a failure.
//
// Finally, note that New returns a nil Matcher when there is no pattern,
// meaning that the target is not running under bisect at all.
// In that common case, the computation of the hash can be avoided entirely
// by checking for m == nil first:
//
//	for each change {
//		if m == nil {
//			enableChange()
//		} else {
//			h := bisect.Hash(file, line)
//			if m.ShouldEnable(h) {
//				enableChange()
//			}
//			if m.ShouldReport(h) {
//				log.Printf("%v %s:%d", bisect.Marker(h), file, line)
//			}
//		}
//	}
//
// # Pattern Syntax
//
// Patterns are generated by the bisect tool and interpreted by [New].
// Users should not have to understand the patterns except when
// debugging a target's bisect support or debugging the bisect tool itself.
//
// The pattern syntax selecting a change is a sequence of bit strings
// separated by + and - operators. Each bit string denotes the set of
// changes with IDs ending in those bits, + is set addition, - is set subtraction,
// and the expression is evaluated in the usual left-to-right order.
// The special binary number “y” denotes the set of all changes,
// standing in for the empty bit string.
// In the expression, all the + operators must appear before all the - operators.
// A leading + adds to an empty set. A leading - subtracts from the set of all
// possible suffixes.
//
// For example:
//
//   - “01+10” and “+01+10” both denote the set of changes
//     with IDs ending with the bits 01 or 10.
//
//   - “01+10-1001” denotes the set of changes with IDs
//     ending with the bits 01 or 10, but excluding those ending in 1001.
//
//   - “-01-1000” and “y-01-1000 both denote the set of all changes
//     with IDs not ending in 01 nor 1000.
//
//   - “0+1-01+001” is not a valid pattern, because all the + operators do not
//     appear before all the - operators.
//
// In the syntaxes described so far, the pattern specifies the changes to
// enable and report. If a pattern is prefixed by a “!”, the meaning
// changes: the pattern specifies the changes to DISABLE and report. This
// mode of operation is needed when a program passes with all changes
// enabled but fails with no changes enabled. In this case, bisect
// searches for minimal sets of changes to disable.
// Put another way, the leading “!” inverts the result from [Matcher.ShouldEnable]
// but does not invert the result from [Matcher.ShouldReport].
//
// As a convenience for manual debugging, “n” is an alias for “!y”,
// meaning to disable and report all changes.
//
// Finally, a leading “v” in the pattern indicates that the reports will be shown
// to the user of bisect to describe the changes involved in a failure.
// At the API level, the leading “v” causes [Matcher.Verbose] to return true.
// See the next section for details.
//
// # Match Reports
//
// The target program must enable only those changed matched
// by the pattern, and it must print a match report for each such change.
// A match report consists of one or more lines of text that will be
// printed by the bisect tool to describe a change implicated in causing
// a failure. Each line in the report for a given change must contain a
// match marker with that change ID, as returned by [Marker].
// The markers are elided when displaying the lines to the user.
//
// A match marker has the form “[bisect-match 0x1234]” where
// 0x1234 is the change ID in hexadecimal.
// An alternate form is “[bisect-match 010101]”, giving the change ID in binary.
//
// When [Matcher.Verbose] returns false, the match reports are only
// being processed by bisect to learn the set of enabled changes,
// not shown to the user, meaning that each report can be a match
// marker on a line by itself, eliding the usual textual description.
// When the textual description is expensive to compute,
// checking [Matcher.Verbose] can help the avoid that expense
// in most runs.
package bisect

// New creates and returns a new Matcher implementing the given pattern.
// The pattern syntax is defined in the package doc comment.
//
// In addition to the pattern syntax syntax, New("") returns nil, nil.
// The nil *Matcher is valid for use: it returns true from ShouldEnable
// and false from ShouldReport for all changes. Callers can avoid calling
// [Hash], [Matcher.ShouldEnable], and [Matcher.ShouldPrint] entirely
// when they recognize the nil Matcher.
func New(pattern string) (*Matcher, error) {
	if pattern == "" {
		return nil, nil
	}

	m := new(Matcher)

	// Allow multiple v, so that “bisect cmd vPATTERN” can force verbose all the time.
	p := pattern
	for len(p) > 0 && p[0] == 'v' {
		m.verbose = true
		p = p[1:]
		if p == "" {
			return nil, &parseError{"invalid pattern syntax: " + pattern}
		}
	}

	// Allow multiple !, each negating the last, so that “bisect cmd !PATTERN” works
	// even when bisect chooses to add its own !.
	m.enable = true
	for len(p) > 0 && p[0] == '!' {
		m.enable = !m.enable
		p = p[1:]
		if p == "" {
			return nil, &parseError{"invalid pattern syntax: " + pattern}
		}
	}

	if p == "n" {
		// n is an alias for !y.
		m.enable = !m.enable
		p = "y"
	}

	// Parse actual pattern syntax.
	result := true
	bits := uint64(0)
	start := 0
	wid := 1 // 1-bit (binary); sometimes 4-bit (hex)
	for i := 0; i <= len(p); i++ {
		// Imagine a trailing - at the end of the pattern to flush final suffix
		c := byte('-')
		if i < len(p) {
			c = p[i]
		}
		if i == start && wid == 1 && c == 'x' { // leading x for hex
			start = i + 1
			wid = 4
			continue
		}
		switch c {
		default:
			return nil, &parseError{"invalid pattern syntax: " + pattern}
		case '2', '3', '4', '5', '6', '7', '8', '9':
			if wid != 4 {
				return nil, &parseError{"invalid pattern syntax: " + pattern}
			}
			fallthrough
		case '0', '1':
			bits <<= wid
			bits |= uint64(c - '0')
		case 'a', 'b', 'c', 'd', 'e', 'f', 'A', 'B', 'C', 'D', 'E', 'F':
			if wid != 4 {
				return nil, &parseError{"invalid pattern syntax: " + pattern}
			}
			bits <<= 4
			bits |= uint64(c&^0x20 - 'A' + 10)
		case 'y':
			if i+1 < len(p) && (p[i+1] == '0' || p[i+1] == '1') {
				return nil, &parseError{"invalid pattern syntax: " + pattern}
			}
			bits = 0
		case '+', '-':
			if c == '+' && result == false {
				// Have already seen a -. Should be - from here on.
				return nil, &parseError{"invalid pattern syntax (+ after -): " + pattern}
			}
			if i > 0 {
				n := (i - start) * wid
				if n > 64 {
					return nil, &parseError{"pattern bits too long: " + pattern}
				}
				if n <= 0 {
					return nil, &parseError{"invalid pattern syntax: " + pattern}
				}
				if p[start] == 'y' {
					n = 0
				}
				mask := uint64(1)<<n - 1
				m.list = append(m.list, cond{mask, bits, result})
			} else if c == '-' {
				// leading - subtracts from complete set
				m.list = append(m.list, cond{0, 0, true})
			}
			bits = 0
			result = c == '+'
			start = i + 1
			wid = 1
		}
	}
	return m, nil
}

// A Matcher is the parsed, compiled form of a PATTERN string.
// The nil *Matcher is valid: it has all changes enabled but none reported.
type Matcher struct {
	verbose bool
	enable  bool   // when true, list is for “enable and report” (when false, “disable and report”)
	list    []cond // conditions; later ones win over earlier ones
}

// A cond is a single condition in the matcher.
// Given an input id, if id&mask == bits, return the result.
type cond struct {
	mask   uint64
	bits   uint64
	result bool
}

// Verbose reports whether the reports will be shown to users
// and need to include a human-readable change description.
// If not, the target can print just the Marker on a line by itself
// and perhaps save some computation.
func (m *Matcher) Verbose() bool {
	return m.verbose
}

// ShouldEnable reports whether the change with the given id should be enabled.
func (m *Matcher) ShouldEnable(id uint64) bool {
	if m == nil {
		return true
	}
	for i := len(m.list) - 1; i >= 0; i-- {
		c := &m.list[i]
		if id&c.mask == c.bits {
			return c.result == m.enable
		}
	}
	return false == m.enable
}

// ShouldReport reports whether the change with the given id should be reported.
func (m *Matcher) ShouldReport(id uint64) bool {
	if m == nil {
		return false
	}
	for i := len(m.list) - 1; i >= 0; i-- {
		c := &m.list[i]
		if id&c.mask == c.bits {
			return c.result
		}
	}
	return false
}

// Marker returns the match marker text to use on any line reporting details
// about a match of the given ID.
// It always returns the hexadecimal format.
func Marker(id uint64) string {
	return string(AppendMarker(nil, id))
}

// AppendMarker is like [Marker] but appends the marker to dst.
func AppendMarker(dst []byte, id uint64) []byte {
	const prefix = "[bisect-match 0x"
	var buf [len(prefix) + 16 + 1]byte
	copy(buf[:], prefix)
	for i := range 16 {
		buf[len(prefix)+i] = "0123456789abcdef"[id>>60]
		id <<= 4
	}
	buf[len(prefix)+16] = ']'
	return append(dst, buf[:]...)
}

// CutMarker finds the first match marker in line and removes it,
// returning the shortened line (with the marker removed),
// the ID from the match marker,
// and whether a marker was found at all.
// If there is no marker, CutMarker returns line, 0, false.
func CutMarker(line string) (short string, id uint64, ok bool) {
	// Find first instance of prefix.
	prefix := "[bisect-match "
	i := 0
	for ; ; i++ {
		if i >= len(line)-len(prefix) {
			return line, 0, false
		}
		if line[i] == '[' && line[i:i+len(prefix)] == prefix {
			break
		}
	}

	// Scan to ].
	j := i + len(prefix)
	for j < len(line) && line[j] != ']' {
		j++
	}
	if j >= len(line) {
		return line, 0, false
	}

	// Parse id.
	idstr := line[i+len(prefix) : j]
	if len(idstr) >= 3 && idstr[:2] == "0x" {
		// parse hex
		if len(idstr) > 2+16 { // max 0x + 16 digits
			return line, 0, false
		}
		for i := 2; i < len(idstr); i++ {
			id <<= 4
			switch c := idstr[i]; {
			case '0' <= c && c <= '9':
				id |= uint64(c - '0')
			case 'a' <= c && c <= 'f':
				id |= uint64(c - 'a' + 10)
			case 'A' <= c && c <= 'F':
				id |= uint64(c - 'A' + 10)
			}
		}
	} else {
		if idstr == "" || len(idstr) > 64 { // min 1 digit, max 64 digits
			return line, 0, false
		}
		// parse binary
		for i := 0; i < len(idstr); i++ {
			id <<= 1
			switch c := idstr[i]; c {
			default:
				return line, 0, false
			case '0', '1':
				id |= uint64(c - '0')
			}
		}
	}

	// Construct shortened line.
	// Remove at most one space from around the marker,
	// so that "foo [marker] bar" shortens to "foo bar".
	j++ // skip ]
	if i > 0 && line[i-1] == ' ' {
		i--
	} else if j < len(line) && line[j] == ' ' {
		j++
	}
	short = line[:i] + line[j:]
	return short, id, true
}

// Hash computes a hash of the data arguments,
// each of which must be of type string, byte, int, uint, int32, uint32, int64, uint64, uintptr, or a slice of one of those types.
func Hash(data ...any) uint64 {
	h := offset64
	for _, v := range data {
		switch v := v.(type) {
		default:
			// Note: Not printing the type, because reflect.ValueOf(v)
			// would make the interfaces prepared by the caller escape
			// and therefore allocate. This way, Hash(file, line) runs
			// without any allocation. It should be clear from the
			// source code calling Hash what the bad argument was.
			panic("bisect.Hash: unexpected argument type")
		case string:
			h = fnvString(h, v)
		case byte:
			h = fnv(h, v)
		case int:
			h = fnvUint64(h, uint64(v))
		case uint:
			h = fnvUint64(h, uint64(v))
		case int32:
			h = fnvUint32(h, uint32(v))
		case uint32:
			h = fnvUint32(h, v)
		case int64:
			h = fnvUint64(h, uint64(v))
		case uint64:
			h = fnvUint64(h, v)
		case uintptr:
			h = fnvUint64(h, uint64(v))
		case []string:
			for _, x := range v {
				h = fnvString(h, x)
			}
		case []byte:
			for _, x := range v {
				h = fnv(h, x)
			}
		case []int:
			for _, x := range v {
				h = fnvUint64(h, uint64(x))
			}
		case []uint:
			for _, x := range v {
				h = fnvUint64(h, uint64(x))
			}
		case []int32:
			for _, x := range v {
				h = fnvUint32(h, uint32(x))
			}
		case []uint32:
			for _, x := range v {
				h = fnvUint32(h, x)
			}
		case []int64:
			for _, x := range v {
				h = fnvUint64(h, uint64(x))
			}
		case []uint64:
			for _, x := range v {
				h = fnvUint64(h, x)
			}
		case []uintptr:
			for _, x := range v {
				h = fnvUint64(h, uint64(x))
			}
		}
	}
	return h
}

// Trivial error implementation, here to avoid importing errors.

type parseError struct{ text string }

func (e *parseError) Error() string { return e.text }

// FNV-1a implementation. See Go's hash/fnv/fnv.go.
// Copied here for simplicity (can handle uints directly)
// and to avoid the dependency.

const (
	offset64 uint64 = 14695981039346656037
	prime64  uint64 = 1099511628211
)

func fnv(h uint64, x byte) uint64 {
	h ^= uint64(x)
	h *= prime64
	return h
}

func fnvString(h uint64, x string) uint64 {
	for i := 0; i < len(x); i++ {
		h ^= uint64(x[i])
		h *= prime64
	}
	return h
}

func fnvUint64(h uint64, x uint64) uint64 {
	for range 8 {
		h ^= uint64(x & 0xFF)
		x >>= 8
		h *= prime64
	}
	return h
}

func fnvUint32(h uint64, x uint32) uint64 {
	for range 4 {
		h ^= uint64(x & 0xFF)
		x >>= 8
		h *= prime64
	}
	return h
}


================================================
FILE: internal/bisect/bisect_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package bisect

import (
	"os"
	"path/filepath"
	"strings"
	"testing"
)

// In order for package bisect to be copied into the standard library
// and used by very low-level packages such as internal/godebug,
// it needs to have no imports at all.
func TestNoImports(t *testing.T) {
	files, err := filepath.Glob("*.go")
	if err != nil {
		t.Fatal(err)
	}
	for _, file := range files {
		if strings.HasSuffix(file, "_test.go") {
			continue
		}
		data, err := os.ReadFile(file)
		if err != nil {
			t.Error(err)
			continue
		}
		if strings.Contains(string(data), "\nimport") {
			t.Errorf("%s contains imports; package bisect must not import other packages", file)
		}
	}
}


================================================
FILE: internal/diff/diff.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package diff computes differences between text files or strings.
package diff

import (
	"fmt"
	"slices"
	"sort"
	"strings"
)

// An Edit describes the replacement of a portion of a text file.
type Edit struct {
	Start, End int    // byte offsets of the region to replace
	New        string // the replacement
}

func (e Edit) String() string {
	return fmt.Sprintf("{Start:%d,End:%d,New:%q}", e.Start, e.End, e.New)
}

// Apply applies a sequence of edits to the src buffer and returns the
// result. Edits are applied in order of start offset; edits with the
// same start offset are applied in they order they were provided.
//
// Apply returns an error if any edit is out of bounds,
// or if any pair of edits is overlapping.
func Apply(src string, edits []Edit) (string, error) {
	edits, size, err := validate(src, edits)
	if err != nil {
		return "", err
	}

	// Apply edits.
	out := make([]byte, 0, size)
	lastEnd := 0
	for _, edit := range edits {
		if lastEnd < edit.Start {
			out = append(out, src[lastEnd:edit.Start]...)
		}
		out = append(out, edit.New...)
		lastEnd = edit.End
	}
	out = append(out, src[lastEnd:]...)

	if len(out) != size {
		panic("wrong size")
	}

	return string(out), nil
}

// ApplyBytes is like Apply, but it accepts a byte slice.
// The result is always a new array.
func ApplyBytes(src []byte, edits []Edit) ([]byte, error) {
	res, err := Apply(string(src), edits)
	return []byte(res), err
}

// validate checks that edits are consistent with src,
// and returns the size of the patched output.
// It may return a different slice.
func validate(src string, edits []Edit) ([]Edit, int, error) {
	if !sort.IsSorted(editsSort(edits)) {
		edits = slices.Clone(edits)
		SortEdits(edits)
	}

	// Check validity of edits and compute final size.
	size := len(src)
	lastEnd := 0
	for _, edit := range edits {
		if !(0 <= edit.Start && edit.Start <= edit.End && edit.End <= len(src)) {
			return nil, 0, fmt.Errorf("diff has out-of-bounds edits")
		}
		if edit.Start < lastEnd {
			return nil, 0, fmt.Errorf("diff has overlapping edits")
		}
		size += len(edit.New) + edit.Start - edit.End
		lastEnd = edit.End
	}

	return edits, size, nil
}

// SortEdits orders a slice of Edits by (start, end) offset.
// This ordering puts insertions (end = start) before deletions
// (end > start) at the same point, but uses a stable sort to preserve
// the order of multiple insertions at the same point.
// (Apply detects multiple deletions at the same point as an error.)
func SortEdits(edits []Edit) {
	sort.Stable(editsSort(edits))
}

type editsSort []Edit

func (a editsSort) Len() int { return len(a) }
func (a editsSort) Less(i, j int) bool {
	if cmp := a[i].Start - a[j].Start; cmp != 0 {
		return cmp < 0
	}
	return a[i].End < a[j].End
}
func (a editsSort) Swap(i, j int) { a[i], a[j] = a[j], a[i] }

// lineEdits expands and merges a sequence of edits so that each
// resulting edit replaces one or more complete lines.
// See ApplyEdits for preconditions.
func lineEdits(src string, edits []Edit) ([]Edit, error) {
	edits, _, err := validate(src, edits)
	if err != nil {
		return nil, err
	}

	// Do all deletions begin and end at the start of a line,
	// and all insertions end with a newline?
	// (This is merely a fast path.)
	for _, edit := range edits {
		if edit.Start >= len(src) || // insertion at EOF
			edit.Start > 0 && src[edit.Start-1] != '\n' || // not at line start
			edit.End > 0 && src[edit.End-1] != '\n' || // not at line start
			edit.New != "" && edit.New[len(edit.New)-1] != '\n' { // partial insert
			goto expand // slow path
		}
	}
	return edits, nil // aligned

expand:
	if len(edits) == 0 {
		return edits, nil // no edits (unreachable due to fast path)
	}
	expanded := make([]Edit, 0, len(edits)) // a guess
	prev := edits[0]
	// TODO(adonovan): opt: start from the first misaligned edit.
	// TODO(adonovan): opt: avoid quadratic cost of string += string.
	for _, edit := range edits[1:] {
		between := src[prev.End:edit.Start]
		if !strings.Contains(between, "\n") {
			// overlapping lines: combine with previous edit.
			prev.New += between + edit.New
			prev.End = edit.End
		} else {
			// non-overlapping lines: flush previous edit.
			expanded = append(expanded, expandEdit(prev, src))
			prev = edit
		}
	}
	return append(expanded, expandEdit(prev, src)), nil // flush final edit
}

// expandEdit returns edit expanded to complete whole lines.
func expandEdit(edit Edit, src string) Edit {
	// Expand start left to start of line.
	// (delta is the zero-based column number of start.)
	start := edit.Start
	if delta := start - 1 - strings.LastIndex(src[:start], "\n"); delta > 0 {
		edit.Start -= delta
		edit.New = src[start-delta:start] + edit.New
	}

	// Expand end right to end of line.
	end := edit.End
	if end > 0 && src[end-1] != '\n' ||
		edit.New != "" && edit.New[len(edit.New)-1] != '\n' {
		if nl := strings.IndexByte(src[end:], '\n'); nl < 0 {
			edit.End = len(src) // extend to EOF
		} else {
			edit.End = end + nl + 1 // extend beyond \n
		}
	}
	edit.New += src[end:edit.End]

	return edit
}


================================================
FILE: internal/diff/diff_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff_test

import (
	"bytes"
	"math/rand"
	"os"
	"os/exec"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
	"unicode/utf8"

	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/diff/difftest"
	"golang.org/x/tools/internal/testenv"
)

func TestApply(t *testing.T) {
	for _, tc := range difftest.TestCases {
		t.Run(tc.Name, func(t *testing.T) {
			got, err := diff.Apply(tc.In, tc.Edits)
			if err != nil {
				t.Fatalf("Apply(Edits) failed: %v", err)
			}
			if got != tc.Out {
				t.Errorf("Apply(Edits): got %q, want %q", got, tc.Out)
			}
			if tc.LineEdits != nil {
				got, err := diff.Apply(tc.In, tc.LineEdits)
				if err != nil {
					t.Fatalf("Apply(LineEdits) failed: %v", err)
				}
				if got != tc.Out {
					t.Errorf("Apply(LineEdits): got %q, want %q", got, tc.Out)
				}
			}
		})
	}
}

func TestNEdits(t *testing.T) {
	for _, tc := range difftest.TestCases {
		edits := diff.Strings(tc.In, tc.Out)
		got, err := diff.Apply(tc.In, edits)
		if err != nil {
			t.Fatalf("Apply failed: %v", err)
		}
		if got != tc.Out {
			t.Fatalf("%s: got %q wanted %q", tc.Name, got, tc.Out)
		}
		if len(edits) < len(tc.Edits) { // should find subline edits
			t.Errorf("got %v, expected %v for %#v", edits, tc.Edits, tc)
		}
	}
}

func TestNRandom(t *testing.T) {
	rnd := rand.New(rand.NewSource(1))
	for i := range 1000 {
		a := randstr(rnd, "abω", 16)
		b := randstr(rnd, "abωc", 16)
		edits := diff.Strings(a, b)
		got, err := diff.Apply(a, edits)
		if err != nil {
			t.Fatalf("Apply failed: %v", err)
		}
		if got != b {
			t.Fatalf("%d: got %q, wanted %q, starting with %q", i, got, b, a)
		}
	}
}

// $ go test -fuzz=FuzzRoundTrip ./internal/diff
func FuzzRoundTrip(f *testing.F) {
	f.Fuzz(func(t *testing.T, a, b string) {
		if !utf8.ValidString(a) || !utf8.ValidString(b) {
			return // inputs must be text
		}
		edits := diff.Strings(a, b)
		got, err := diff.Apply(a, edits)
		if err != nil {
			t.Fatalf("Apply failed: %v", err)
		}
		if got != b {
			t.Fatalf("applying diff(%q, %q) gives %q; edits=%v", a, b, got, edits)
		}
	})
}

func TestLineEdits(t *testing.T) {
	for _, tc := range difftest.TestCases {
		t.Run(tc.Name, func(t *testing.T) {
			want := tc.LineEdits
			if want == nil {
				want = tc.Edits // already line-aligned
			}
			got, err := diff.LineEdits(tc.In, tc.Edits)
			if err != nil {
				t.Fatalf("LineEdits: %v", err)
			}
			if !reflect.DeepEqual(got, want) {
				t.Errorf("in=<<%s>>\nout=<<%s>>\nraw  edits=%s\nline edits=%s\nwant: %s",
					tc.In, tc.Out, tc.Edits, got, want)
			}
			// make sure that applying the edits gives the expected result
			fixed, err := diff.Apply(tc.In, got)
			if err != nil {
				t.Error(err)
			}
			if fixed != tc.Out {
				t.Errorf("Apply(LineEdits): got %q, want %q", fixed, tc.Out)
			}
		})
	}
}

func TestToUnified(t *testing.T) {
	testenv.NeedsTool(t, "patch")
	for _, tc := range difftest.TestCases {
		t.Run(tc.Name, func(t *testing.T) {
			nedits := diff.Lines(tc.In, tc.Out)
			xunified, err := diff.ToUnified(difftest.FileA, difftest.FileB, tc.In, nedits, diff.DefaultContextLines)
			if err != nil {
				t.Fatal(err)
			}
			if xunified == "" {
				return
			}
			orig := filepath.Join(t.TempDir(), "original")
			err = os.WriteFile(orig, []byte(tc.In), 0644)
			if err != nil {
				t.Fatal(err)
			}
			temp := filepath.Join(t.TempDir(), "patched")
			err = os.WriteFile(temp, []byte(tc.In), 0644)
			if err != nil {
				t.Fatal(err)
			}
			cmd := exec.Command("patch", "-p0", "-u", "-s", "-o", temp, orig)
			cmd.Stdin = strings.NewReader(xunified)
			cmd.Stdout = new(bytes.Buffer)
			cmd.Stderr = new(bytes.Buffer)
			if err = cmd.Run(); err != nil {
				t.Fatalf("%v: %q (%q) (%q)", err, cmd.String(),
					cmd.Stderr, cmd.Stdout)
			}
			got, err := os.ReadFile(temp)
			if err != nil {
				t.Fatal(err)
			}
			if string(got) != tc.Out {
				t.Errorf("applying unified failed: got\n%q, wanted\n%q unified\n%q",
					got, tc.Out, xunified)
			}

		})
	}
}

func TestRegressionOld001(t *testing.T) {
	a := "// Copyright 2019 The Go Authors. All rights reserved.\n// Use of this source code is governed by a BSD-style\n// license that can be found in the LICENSE file.\n\npackage diff_test\n\nimport (\n\t\"fmt\"\n\t\"math/rand\"\n\t\"strings\"\n\t\"testing\"\n\n\t\"golang.org/x/tools/gopls/internal/lsp/diff\"\n\t\"golang.org/x/tools/internal/diff/difftest\"\n\t\"golang.org/x/tools/gopls/internal/span\"\n)\n"

	b := "// Copyright 2019 The Go Authors. All rights reserved.\n// Use of this source code is governed by a BSD-style\n// license that can be found in the LICENSE file.\n\npackage diff_test\n\nimport (\n\t\"fmt\"\n\t\"math/rand\"\n\t\"strings\"\n\t\"testing\"\n\n\t\"github.com/google/safehtml/template\"\n\t\"golang.org/x/tools/gopls/internal/lsp/diff\"\n\t\"golang.org/x/tools/internal/diff/difftest\"\n\t\"golang.org/x/tools/gopls/internal/span\"\n)\n"
	diffs := diff.Strings(a, b)
	got, err := diff.Apply(a, diffs)
	if err != nil {
		t.Fatalf("Apply failed: %v", err)
	}
	if got != b {
		i := 0
		for ; i < len(a) && i < len(b) && got[i] == b[i]; i++ {
		}
		t.Errorf("oops %vd\n%q\n%q", diffs, got, b)
		t.Errorf("\n%q\n%q", got[i:], b[i:])
	}
}

func TestRegressionOld002(t *testing.T) {
	a := "n\"\n)\n"
	b := "n\"\n\t\"golang.org/x//nnal/stack\"\n)\n"
	diffs := diff.Strings(a, b)
	got, err := diff.Apply(a, diffs)
	if err != nil {
		t.Fatalf("Apply failed: %v", err)
	}
	if got != b {
		i := 0
		for ; i < len(a) && i < len(b) && got[i] == b[i]; i++ {
		}
		t.Errorf("oops %vd\n%q\n%q", diffs, got, b)
		t.Errorf("\n%q\n%q", got[i:], b[i:])
	}
}

// return a random string of length n made of characters from s
func randstr(rnd *rand.Rand, s string, n int) string {
	src := []rune(s)
	x := make([]rune, n)
	for i := range n {
		x[i] = src[rnd.Intn(len(src))]
	}
	return string(x)
}


================================================
FILE: internal/diff/difftest/difftest.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package difftest supplies a set of tests that will operate on any
// implementation of a diff algorithm as exposed by
// "golang.org/x/tools/internal/diff"
package difftest

// There are two kinds of tests, semantic tests, and 'golden data' tests.
// The semantic tests check that the computed diffs transform the input to
// the output, and that 'patch' accepts the computed unified diffs.
// The other tests just check that Edits and LineEdits haven't changed
// unexpectedly. These fields may need to be changed when the diff algorithm
// changes.

import (
	"testing"

	"golang.org/x/tools/internal/diff"
)

const (
	FileA         = "from"
	FileB         = "to"
	UnifiedPrefix = "--- " + FileA + "\n+++ " + FileB + "\n"
)

var TestCases = []struct {
	Name, In, Out, Unified string
	Edits, LineEdits       []diff.Edit // expectation (LineEdits=nil => already line-aligned)
	NoDiff                 bool
}{{
	Name: "empty",
	In:   "",
	Out:  "",
}, {
	Name: "no_diff",
	In:   "gargantuan\n",
	Out:  "gargantuan\n",
}, {
	Name: "replace_all",
	In:   "fruit\n",
	Out:  "cheese\n",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-fruit
+cheese
`[1:],
	Edits:     []diff.Edit{{Start: 0, End: 5, New: "cheese"}},
	LineEdits: []diff.Edit{{Start: 0, End: 6, New: "cheese\n"}},
}, {
	Name: "insert_rune",
	In:   "gord\n",
	Out:  "gourd\n",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-gord
+gourd
`[1:],
	Edits:     []diff.Edit{{Start: 2, End: 2, New: "u"}},
	LineEdits: []diff.Edit{{Start: 0, End: 5, New: "gourd\n"}},
}, {
	Name: "delete_rune",
	In:   "groat\n",
	Out:  "goat\n",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-groat
+goat
`[1:],
	Edits:     []diff.Edit{{Start: 1, End: 2, New: ""}},
	LineEdits: []diff.Edit{{Start: 0, End: 6, New: "goat\n"}},
}, {
	Name: "replace_rune",
	In:   "loud\n",
	Out:  "lord\n",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-loud
+lord
`[1:],
	Edits:     []diff.Edit{{Start: 2, End: 3, New: "r"}},
	LineEdits: []diff.Edit{{Start: 0, End: 5, New: "lord\n"}},
}, {
	Name: "replace_partials",
	In:   "blanket\n",
	Out:  "bunker\n",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-blanket
+bunker
`[1:],
	Edits: []diff.Edit{
		{Start: 1, End: 3, New: "u"},
		{Start: 6, End: 7, New: "r"},
	},
	LineEdits: []diff.Edit{{Start: 0, End: 8, New: "bunker\n"}},
}, {
	Name: "insert_line",
	In:   "1: one\n3: three\n",
	Out:  "1: one\n2: two\n3: three\n",
	Unified: UnifiedPrefix + `
@@ -1,2 +1,3 @@
 1: one
+2: two
 3: three
`[1:],
	Edits: []diff.Edit{{Start: 7, End: 7, New: "2: two\n"}},
}, {
	Name: "replace_no_newline",
	In:   "A",
	Out:  "B",
	Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+B
\ No newline at end of file
`[1:],
	Edits: []diff.Edit{{Start: 0, End: 1, New: "B"}},
}, {
	Name: "delete_empty",
	In:   "meow",
	Out:  "", // GNU diff -u special case: +0,0
	Unified: UnifiedPrefix + `
@@ -1 +0,0 @@
-meow
\ No newline at end of file
`[1:],
	Edits:     []diff.Edit{{Start: 0, End: 4, New: ""}},
	LineEdits: []diff.Edit{{Start: 0, End: 4, New: ""}},
}, {
	Name: "append_empty",
	In:   "", // GNU diff -u special case: -0,0
	Out:  "AB\nC",
	Unified: UnifiedPrefix + `
@@ -0,0 +1,2 @@
+AB
+C
\ No newline at end of file
`[1:],
	Edits:     []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
	LineEdits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
},
	// TODO(adonovan): fix this test: GNU diff -u prints "+1,2", Unifies prints "+1,3".
	// 	{
	// 		Name: "add_start",
	// 		In:   "A",
	// 		Out:  "B\nCA",
	// 		Unified: UnifiedPrefix + `
	// @@ -1 +1,2 @@
	// -A
	// \ No newline at end of file
	// +B
	// +CA
	// \ No newline at end of file
	// `[1:],
	// 		Edits:     []diff.TextEdit{{Span: newSpan(0, 0), NewText: "B\nC"}},
	// 		LineEdits: []diff.TextEdit{{Span: newSpan(0, 0), NewText: "B\nC"}},
	// 	},
	{
		Name: "add_end",
		In:   "A",
		Out:  "AB",
		Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+AB
\ No newline at end of file
`[1:],
		Edits:     []diff.Edit{{Start: 1, End: 1, New: "B"}},
		LineEdits: []diff.Edit{{Start: 0, End: 1, New: "AB"}},
	}, {
		Name: "add_empty",
		In:   "",
		Out:  "AB\nC",
		Unified: UnifiedPrefix + `
@@ -0,0 +1,2 @@
+AB
+C
\ No newline at end of file
`[1:],
		Edits:     []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
		LineEdits: []diff.Edit{{Start: 0, End: 0, New: "AB\nC"}},
	}, {
		Name: "add_newline",
		In:   "A",
		Out:  "A\n",
		Unified: UnifiedPrefix + `
@@ -1 +1 @@
-A
\ No newline at end of file
+A
`[1:],
		Edits:     []diff.Edit{{Start: 1, End: 1, New: "\n"}},
		LineEdits: []diff.Edit{{Start: 0, End: 1, New: "A\n"}},
	}, {
		Name: "delete_front",
		In:   "A\nB\nC\nA\nB\nB\nA\n",
		Out:  "C\nB\nA\nB\nA\nC\n",
		Unified: UnifiedPrefix + `
@@ -1,7 +1,6 @@
-A
+C
B
-C
A
-B
B
A
+C
`[1:],
		NoDiff: true, // unified diff is different but valid
		Edits: []diff.Edit{
			{Start: 0, End: 2, New: "C\n"},
			{Start: 4, End: 6, New: ""},
			{Start: 8, End: 10, New: ""},
			{Start: 14, End: 14, New: "C\n"},
		},
		LineEdits: []diff.Edit{
			{Start: 0, End: 2, New: "C\n"},
			{Start: 4, End: 6, New: ""},
			{Start: 8, End: 10, New: ""},
			{Start: 14, End: 14, New: "C\n"},
		},
	}, {
		Name: "replace_last_line",
		In:   "A\nB\n",
		Out:  "A\nC\n\n",
		Unified: UnifiedPrefix + `
@@ -1,2 +1,3 @@
 A
-B
+C
+
`[1:],
		Edits:     []diff.Edit{{Start: 2, End: 3, New: "C\n"}},
		LineEdits: []diff.Edit{{Start: 2, End: 4, New: "C\n\n"}},
	},
	{
		Name: "multiple_replace",
		In:   "A\nB\nC\nD\nE\nF\nG\n",
		Out:  "A\nH\nI\nJ\nE\nF\nK\n",
		Unified: UnifiedPrefix + `
@@ -1,7 +1,7 @@
 A
-B
-C
-D
+H
+I
+J
 E
 F
-G
+K
`[1:],
		Edits: []diff.Edit{
			{Start: 2, End: 8, New: "H\nI\nJ\n"},
			{Start: 12, End: 14, New: "K\n"},
		},
		NoDiff: true, // diff algorithm produces different delete/insert pattern
	},
	{
		Name:  "extra_newline",
		In:    "\nA\n",
		Out:   "A\n",
		Edits: []diff.Edit{{Start: 0, End: 1, New: ""}},
		Unified: UnifiedPrefix + `@@ -1,2 +1 @@
-
 A
`,
	}, {
		Name:      "unified_lines",
		In:        "aaa\nccc\n",
		Out:       "aaa\nbbb\nccc\n",
		Edits:     []diff.Edit{{Start: 4, End: 4, New: "bbb\n"}},
		LineEdits: []diff.Edit{{Start: 4, End: 4, New: "bbb\n"}},
		Unified:   UnifiedPrefix + "@@ -1,2 +1,3 @@\n aaa\n+bbb\n ccc\n",
	}, {
		Name: "60379",
		In: `package a

type S struct {
s fmt.Stringer
}
`,
		Out: `package a

type S struct {
	s fmt.Stringer
}
`,
		Edits:     []diff.Edit{{Start: 27, End: 27, New: "\t"}},
		LineEdits: []diff.Edit{{Start: 27, End: 42, New: "\ts fmt.Stringer\n"}},
		Unified:   UnifiedPrefix + "@@ -1,5 +1,5 @@\n package a\n \n type S struct {\n-s fmt.Stringer\n+\ts fmt.Stringer\n }\n",
	},
}

func DiffTest(t *testing.T, compute func(before, after string) []diff.Edit) {
	for _, test := range TestCases {
		t.Run(test.Name, func(t *testing.T) {
			edits := compute(test.In, test.Out)
			got, err := diff.Apply(test.In, edits)
			if err != nil {
				t.Fatalf("Apply failed: %v", err)
			}
			unified, err := diff.ToUnified(FileA, FileB, test.In, edits, diff.DefaultContextLines)
			if err != nil {
				t.Fatalf("ToUnified: %v", err)
			}
			if got != test.Out {
				t.Errorf("Apply: got patched:\n%v\nfrom diff:\n%v\nexpected:\n%v",
					got, unified, test.Out)
			}
			if !test.NoDiff && unified != test.Unified {
				t.Errorf("Unified: got diff:\n%q\nexpected:\n%q diffs:%v",
					unified, test.Unified, edits)
			}
		})
	}
}


================================================
FILE: internal/diff/difftest/difftest_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package difftest supplies a set of tests that will operate on any
// implementation of a diff algorithm as exposed by
// "golang.org/x/tools/internal/diff"
package difftest_test

import (
	"fmt"
	"os"
	"os/exec"
	"strings"
	"testing"

	"golang.org/x/tools/internal/diff/difftest"
	"golang.org/x/tools/internal/testenv"
)

// check that the TestCases match diff -u output
func TestVerifyUnified(t *testing.T) {
	testenv.NeedsTool(t, "diff")
	for _, test := range difftest.TestCases {
		t.Run(test.Name, func(t *testing.T) {
			if test.NoDiff {
				t.Skip("diff tool produces expected different results")
			}
			diff, err := getDiffOutput(test.In, test.Out)
			if err != nil {
				t.Fatal(err)
			}
			if len(diff) > 0 {
				diff = difftest.UnifiedPrefix + diff
			}
			if diff != test.Unified {
				t.Errorf("unified:\n%s\ndiff -u:\n%s", test.Unified, diff)
			}
		})
	}
}

func getDiffOutput(a, b string) (string, error) {
	fileA, err := os.CreateTemp("", "myers.in")
	if err != nil {
		return "", err
	}
	defer os.Remove(fileA.Name())
	if _, err := fileA.Write([]byte(a)); err != nil {
		return "", err
	}
	if err := fileA.Close(); err != nil {
		return "", err
	}
	fileB, err := os.CreateTemp("", "myers.in")
	if err != nil {
		return "", err
	}
	defer os.Remove(fileB.Name())
	if _, err := fileB.Write([]byte(b)); err != nil {
		return "", err
	}
	if err := fileB.Close(); err != nil {
		return "", err
	}
	cmd := exec.Command("diff", "-u", fileA.Name(), fileB.Name())
	cmd.Env = append(cmd.Env, "LANG=en_US.UTF-8")
	out, err := cmd.Output()
	if err != nil {
		exit, ok := err.(*exec.ExitError)
		if !ok {
			return "", fmt.Errorf("can't exec %s: %v", cmd, err)
		}
		if len(out) == 0 {
			// Nonzero exit with no output: terminated by signal?
			return "", fmt.Errorf("%s failed: %v; stderr:\n%s", cmd, err, exit.Stderr)
		}
		// nonzero exit + output => files differ
	}
	diff := string(out)
	if len(diff) <= 0 {
		return diff, nil
	}
	bits := strings.SplitN(diff, "\n", 3)
	if len(bits) != 3 {
		return "", fmt.Errorf("diff output did not have file prefix:\n%s", diff)
	}
	return bits[2], nil
}


================================================
FILE: internal/diff/export_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff

// This file exports some private declarations to tests.

var LineEdits = lineEdits


================================================
FILE: internal/diff/lcs/common.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

import (
	"log"
	"sort"
)

// lcs is a longest common sequence
type lcs []diag

// A diag is a piece of the edit graph where A[X+i] == B[Y+i], for 0<=i<Len.
// All computed diagonals are parts of a longest common subsequence.
type diag struct {
	X, Y int
	Len  int
}

// sort sorts in place, by lowest X, and if tied, inversely by Len
func (l lcs) sort() lcs {
	sort.Slice(l, func(i, j int) bool {
		if l[i].X != l[j].X {
			return l[i].X < l[j].X
		}
		return l[i].Len > l[j].Len
	})
	return l
}

// validate that the elements of the lcs do not overlap
// (can only happen when the two-sided algorithm ends early)
// expects the lcs to be sorted
func (l lcs) valid() bool {
	for i := 1; i < len(l); i++ {
		if l[i-1].X+l[i-1].Len > l[i].X {
			return false
		}
		if l[i-1].Y+l[i-1].Len > l[i].Y {
			return false
		}
	}
	return true
}

// repair overlapping lcs
// only called if two-sided stops early
func (l lcs) fix() lcs {
	// from the set of diagonals in l, find a maximal non-conflicting set
	// this problem may be NP-complete, but we use a greedy heuristic,
	// which is quadratic, but with a better data structure, could be D log D.
	// independent is not enough: {0,3,1} and {3,0,2} can't both occur in an lcs
	// which has to have monotone x and y
	if len(l) == 0 {
		return nil
	}
	sort.Slice(l, func(i, j int) bool { return l[i].Len > l[j].Len })
	tmp := make(lcs, 0, len(l))
	tmp = append(tmp, l[0])
	for i := 1; i < len(l); i++ {
		var dir direction
		nxt := l[i]
		for _, in := range tmp {
			if dir, nxt = overlap(in, nxt); dir == empty || dir == bad {
				break
			}
		}
		if nxt.Len > 0 && dir != bad {
			tmp = append(tmp, nxt)
		}
	}
	tmp.sort()
	if false && !tmp.valid() { // debug checking
		log.Fatalf("here %d", len(tmp))
	}
	return tmp
}

type direction int

const (
	empty    direction = iota // diag is empty (so not in lcs)
	leftdown                  // proposed acceptably to the left and below
	rightup                   // proposed diag is acceptably to the right and above
	bad                       // proposed diag is inconsistent with the lcs so far
)

// overlap trims the proposed diag prop  so it doesn't overlap with
// the existing diag that has already been added to the lcs.
func overlap(exist, prop diag) (direction, diag) {
	if prop.X <= exist.X && exist.X < prop.X+prop.Len {
		// remove the end of prop where it overlaps with the X end of exist
		delta := prop.X + prop.Len - exist.X
		prop.Len -= delta
		if prop.Len <= 0 {
			return empty, prop
		}
	}
	if exist.X <= prop.X && prop.X < exist.X+exist.Len {
		// remove the beginning of prop where overlaps with exist
		delta := exist.X + exist.Len - prop.X
		prop.Len -= delta
		if prop.Len <= 0 {
			return empty, prop
		}
		prop.X += delta
		prop.Y += delta
	}
	if prop.Y <= exist.Y && exist.Y < prop.Y+prop.Len {
		// remove the end of prop that overlaps (in Y) with exist
		delta := prop.Y + prop.Len - exist.Y
		prop.Len -= delta
		if prop.Len <= 0 {
			return empty, prop
		}
	}
	if exist.Y <= prop.Y && prop.Y < exist.Y+exist.Len {
		// remove the beginning of peop that overlaps with exist
		delta := exist.Y + exist.Len - prop.Y
		prop.Len -= delta
		if prop.Len <= 0 {
			return empty, prop
		}
		prop.X += delta // no test reaches this code
		prop.Y += delta
	}
	if prop.X+prop.Len <= exist.X && prop.Y+prop.Len <= exist.Y {
		return leftdown, prop
	}
	if exist.X+exist.Len <= prop.X && exist.Y+exist.Len <= prop.Y {
		return rightup, prop
	}
	// prop can't be in an lcs that contains exist
	return bad, prop
}

// manipulating Diag and lcs

// prepend a diagonal (x,y)-(x+1,y+1) segment either to an empty lcs
// or to its first Diag. prepend is only called to extend diagonals
// the backward direction.
func (lcs lcs) prepend(x, y int) lcs {
	if len(lcs) > 0 {
		d := &lcs[0]
		if int(d.X) == x+1 && int(d.Y) == y+1 {
			// extend the diagonal down and to the left
			d.X, d.Y = int(x), int(y)
			d.Len++
			return lcs
		}
	}

	r := diag{X: int(x), Y: int(y), Len: 1}
	lcs = append([]diag{r}, lcs...)
	return lcs
}

// append appends a diagonal, or extends the existing one.
// by adding the edge (x,y)-(x+1.y+1). append is only called
// to extend diagonals in the forward direction.
func (lcs lcs) append(x, y int) lcs {
	if len(lcs) > 0 {
		last := &lcs[len(lcs)-1]
		// Expand last element if adjoining.
		if last.X+last.Len == x && last.Y+last.Len == y {
			last.Len++
			return lcs
		}
	}

	return append(lcs, diag{X: x, Y: y, Len: 1})
}

// enforce constraint on d, k
func ok(d, k int) bool {
	return d >= 0 && -d <= k && k <= d
}


================================================
FILE: internal/diff/lcs/common_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

import (
	"log"
	"math/rand/v2"
	"slices"
	"strings"
	"testing"
)

type Btest struct {
	a, b string
	lcs  []string
}

var Btests = []Btest{
	{"aaabab", "abaab", []string{"abab", "aaab"}},
	{"aabbba", "baaba", []string{"aaba"}},
	{"cabbx", "cbabx", []string{"cabx", "cbbx"}},
	{"c", "cb", []string{"c"}},
	{"aaba", "bbb", []string{"b"}},
	{"bbaabb", "b", []string{"b"}},
	{"baaabb", "bbaba", []string{"bbb", "baa", "bab"}},
	{"baaabb", "abbab", []string{"abb", "bab", "aab"}},
	{"baaba", "aaabba", []string{"aaba"}},
	{"ca", "cba", []string{"ca"}},
	{"ccbcbc", "abba", []string{"bb"}},
	{"ccbcbc", "aabba", []string{"bb"}},
	{"ccb", "cba", []string{"cb"}},
	{"caef", "axe", []string{"ae"}},
	{"bbaabb", "baabb", []string{"baabb"}},
	// Example from Myers:
	{"abcabba", "cbabac", []string{"caba", "baba", "cbba"}},
	{"3456aaa", "aaa", []string{"aaa"}},
	{"aaa", "aaa123", []string{"aaa"}},
	{"aabaa", "aacaa", []string{"aaaa"}},
	{"1a", "a", []string{"a"}},
	{"abab", "bb", []string{"bb"}},
	{"123", "ab", []string{""}},
	{"a", "b", []string{""}},
	{"abc", "123", []string{""}},
	{"aa", "aa", []string{"aa"}},
	{"abcde", "12345", []string{""}},
	{"aaa3456", "aaa", []string{"aaa"}},
	{"abcde", "12345a", []string{"a"}},
	{"ab", "123", []string{""}},
	{"1a2", "a", []string{"a"}},
	// for two-sided
	{"babaab", "cccaba", []string{"aba"}},
	{"aabbab", "cbcabc", []string{"bab"}},
	{"abaabb", "bcacab", []string{"baab"}},
	{"abaabb", "abaaaa", []string{"abaa"}},
	{"bababb", "baaabb", []string{"baabb"}},
	{"abbbaa", "cabacc", []string{"aba"}},
	{"aabbaa", "aacaba", []string{"aaaa", "aaba"}},
}

type stringSeqs struct{ a, b string }

func (s stringSeqs) lengths() (int, int) { return len(s.a), len(s.b) }
func (s stringSeqs) commonPrefixLen(ai, aj, bi, bj int) int {
	return commonPrefixLenString(s.a[ai:aj], s.b[bi:bj])
}
func (s stringSeqs) commonSuffixLen(ai, aj, bi, bj int) int {
	return commonSuffixLenString(s.a[ai:aj], s.b[bi:bj])
}

func commonPrefixLenString(a, b string) int {
	n := min(len(a), len(b))
	i := 0
	for i < n && a[i] == b[i] {
		i++
	}
	return i
}
func commonSuffixLenString(a, b string) int {
	n := min(len(a), len(b))
	i := 0
	for i < n && a[len(a)-1-i] == b[len(b)-1-i] {
		i++
	}
	return i
}

func init() {
	log.SetFlags(log.Lshortfile)
}

func check(t *testing.T, str string, lcs lcs, want []string) {
	t.Helper()
	if !lcs.valid() {
		t.Errorf("bad lcs %v", lcs)
	}
	var got strings.Builder
	for _, dd := range lcs {
		got.WriteString(str[dd.X : dd.X+dd.Len])
	}
	ans := got.String()
	if slices.Contains(want, ans) {
		return
	}
	t.Fatalf("str=%q lcs=%v want=%q got=%q", str, lcs, want, ans)
}

func checkDiffs(t *testing.T, before string, diffs []Diff, after string) {
	t.Helper()
	var ans strings.Builder
	sofar := 0 // index of position in before
	for _, d := range diffs {
		if sofar < d.Start {
			ans.WriteString(before[sofar:d.Start])
		}
		ans.WriteString(after[d.ReplStart:d.ReplEnd])
		sofar = d.End
	}
	ans.WriteString(before[sofar:])
	if ans.String() != after {
		t.Fatalf("diff %v took %q to %q, not to %q", diffs, before, ans.String(), after)
	}
}

func lcslen(l lcs) int {
	ans := 0
	for _, d := range l {
		ans += int(d.Len)
	}
	return ans
}

// return a random string of length n made of characters from s
func randstr(rng *rand.Rand, s string, n int) string {
	src := []rune(s)
	x := make([]rune, n)
	for i := range n {
		x[i] = src[rng.Int64N(int64(len(src)))]
	}
	return string(x)
}

func TestLcsFix(t *testing.T) {
	tests := []struct{ before, after lcs }{
		{lcs{diag{0, 0, 3}, diag{2, 2, 5}, diag{3, 4, 5}, diag{8, 9, 4}}, lcs{diag{0, 0, 2}, diag{2, 2, 1}, diag{3, 4, 5}, diag{8, 9, 4}}},
		{lcs{diag{1, 1, 6}, diag{6, 12, 3}}, lcs{diag{1, 1, 5}, diag{6, 12, 3}}},
		{lcs{diag{0, 0, 4}, diag{3, 5, 4}}, lcs{diag{0, 0, 3}, diag{3, 5, 4}}},
		{lcs{diag{0, 20, 1}, diag{0, 0, 3}, diag{1, 20, 4}}, lcs{diag{0, 0, 3}, diag{3, 22, 2}}},
		{lcs{diag{0, 0, 4}, diag{1, 1, 2}}, lcs{diag{0, 0, 4}}},
		{lcs{diag{0, 0, 4}}, lcs{diag{0, 0, 4}}},
		{lcs{}, lcs{}},
		{lcs{diag{0, 0, 4}, diag{1, 1, 6}, diag{3, 3, 2}}, lcs{diag{0, 0, 1}, diag{1, 1, 6}}},
	}
	for n, x := range tests {
		got := x.before.fix()
		if len(got) != len(x.after) {
			t.Errorf("got %v, expected %v, for %v", got, x.after, x.before)
		}
		olen := lcslen(x.after)
		glen := lcslen(got)
		if olen != glen {
			t.Errorf("%d: lens(%d,%d) differ, %v, %v, %v", n, glen, olen, got, x.after, x.before)
		}
	}
}


================================================
FILE: internal/diff/lcs/doc.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// package lcs contains code to find longest-common-subsequences
// (and diffs)
package lcs

/*
Compute longest-common-subsequences of two slices A, B using
algorithms from Myers' paper. A longest-common-subsequence
(LCS from now on) of A and B is a maximal set of lexically increasing
pairs of subscripts (x,y) with A[x]==B[y]. There may be many LCS, but
they all have the same length. An LCS determines a sequence of edits
that changes A into B.

The key concept is the edit graph of A and B.
If A has length N and B has length M, then the edit graph has
vertices v[i][j] for 0 <= i <= N, 0 <= j <= M. There is a
horizontal edge from v[i][j] to v[i+1][j] whenever both are in
the graph, and a vertical edge from v[i][j] to f[i][j+1] similarly.
When A[i] == B[j] there is a diagonal edge from v[i][j] to v[i+1][j+1].

A path between in the graph between (0,0) and (N,M) determines a sequence
of edits converting A into B: each horizontal edge corresponds to removing
an element of A, and each vertical edge corresponds to inserting an
element of B.

A vertex (x,y) is on (forward) diagonal k if x-y=k. A path in the graph
is of length D if it has D non-diagonal edges. The algorithms generate
forward paths (in which at least one of x,y increases at each edge),
or backward paths (in which at least one of x,y decreases at each edge),
or a combination. (Note that the orientation is the traditional mathematical one,
with the origin in the lower-left corner.)

Here is the edit graph for A:"aabbaa", B:"aacaba". (I know the diagonals look weird.)
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   b      |             |             |   ___/‾‾‾   |   ___/‾‾‾   |             |             |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   c      |             |             |             |             |             |             |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
                 a             a             b             b             a             a


The algorithm labels a vertex (x,y) with D,k if it is on diagonal k and at
the end of a maximal path of length D. (Because x-y=k it suffices to remember
only the x coordinate of the vertex.)

The forward algorithm: Find the longest diagonal starting at (0,0) and
label its end with D=0,k=0. From that vertex take a vertical step and
then follow the longest diagonal (up and to the right), and label that vertex
with D=1,k=-1. From the D=0,k=0 point take a horizontal step and the follow
the longest diagonal (up and to the right) and label that vertex
D=1,k=1. In the same way, having labelled all the D vertices,
from a vertex labelled D,k find two vertices
tentatively labelled D+1,k-1 and D+1,k+1. There may be two on the same
diagonal, in which case take the one with the larger x.

Eventually the path gets to (N,M), and the diagonals on it are the LCS.

Here is the edit graph with the ends of D-paths labelled. (So, for instance,
0/2,2 indicates that x=2,y=2 is labelled with 0, as it should be, since the first
step is to go up the longest diagonal from (0,0).)
A:"aabbaa", B:"aacaba"
          ⊙   -------   ⊙   -------   ⊙   -------(3/3,6)-------   ⊙   -------(3/5,6)-------(4/6,6)
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------(2/3,5)-------   ⊙   -------   ⊙   -------   ⊙
   b      |             |             |   ___/‾‾‾   |   ___/‾‾‾   |             |             |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------(3/5,4)-------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------(1/2,3)-------(2/3,3)-------   ⊙   -------   ⊙   -------   ⊙
   c      |             |             |             |             |             |             |
          ⊙   -------   ⊙   -------(0/2,2)-------(1/3,2)-------(2/4,2)-------(3/5,2)-------(4/6,2)
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
   a      |   ___/‾‾‾   |   ___/‾‾‾   |             |             |   ___/‾‾‾   |   ___/‾‾‾   |
          ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙   -------   ⊙
                 a             a             b             b             a             a

The 4-path is reconstructed starting at (4/6,6), horizontal to (3/5,6), diagonal to (3,4), vertical
to (2/3,3), horizontal to (1/2,3), vertical to (0/2,2), and diagonal to (0,0). As expected,
there are 4 non-diagonal steps, and the diagonals form an LCS.

There is a symmetric backward algorithm, which gives (backwards labels are prefixed with a colon):
A:"aabbaa", B:"aacaba"
            ⊙   --------    ⊙   --------    ⊙   --------    ⊙   --------    ⊙   --------    ⊙   --------    ⊙
    a       |   ____/‾‾‾    |   ____/‾‾‾    |               |               |   ____/‾‾‾    |   ____/‾‾‾    |
            ⊙   --------    ⊙   --------    ⊙   --------    ⊙   --------    ⊙   --------(:0/5,5)--------    ⊙
    b       |               |               |   ____/‾‾‾    |   ____/‾‾‾    |               |               |
            ⊙   --------    ⊙   --------    ⊙   --------(:1/3,4)--------    ⊙   --------    ⊙   --------    ⊙
    a       |   ____/‾‾‾    |   ____/‾‾‾    |               |               |   ____/‾‾‾    |   ____/‾‾‾    |
        (:3/0,3)--------(:2/1,3)--------    ⊙   --------(:2/3,3)--------(:1/4,3)--------    ⊙   --------    ⊙
    c       |               |               |               |               |               |               |
            ⊙   --------    ⊙   --------    ⊙   --------(:3/3,2)--------(:2/4,2)--------    ⊙   --------    ⊙
    a       |   ____/‾‾‾    |   ____/‾‾‾    |               |               |   ____/‾‾‾    |   ____/‾‾‾    |
        (:3/0,1)--------    ⊙   --------    ⊙   --------    ⊙   --------(:3/4,1)--------    ⊙   --------    ⊙
    a       |   ____/‾‾‾    |   ____/‾‾‾    |               |               |   ____/‾‾‾    |   ____/‾‾‾    |
        (:4/0,0)--------    ⊙   --------    ⊙   --------    ⊙   --------(:4/4,0)--------    ⊙   --------    ⊙
                    a               a               b               b               a               a

Neither of these is ideal for use in an editor, where it is undesirable to send very long diffs to the
front end. It's tricky to decide exactly what 'very long diffs' means, as "replace A by B" is very short.
We want to control how big D can be, by stopping when it gets too large. The forward algorithm then
privileges common prefixes, and the backward algorithm privileges common suffixes. Either is an undesirable
asymmetry.

Fortunately there is a two-sided algorithm, implied by results in Myers' paper. Here's what the labels in
the edit graph look like.
A:"aabbaa", B:"aacaba"
             ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙
    a        |    ____/‾‾‾‾    |    ____/‾‾‾‾    |                 |                 |    ____/‾‾‾‾    |    ____/‾‾‾‾    |
             ⊙    ---------    ⊙    ---------    ⊙    --------- (2/3,5) ---------    ⊙    --------- (:0/5,5)---------    ⊙
    b        |                 |                 |    ____/‾‾‾‾    |    ____/‾‾‾‾    |                 |                 |
             ⊙    ---------    ⊙    ---------    ⊙    --------- (:1/3,4)---------    ⊙    ---------    ⊙    ---------    ⊙
    a        |    ____/‾‾‾‾    |    ____/‾‾‾‾    |                 |                 |    ____/‾‾‾‾    |    ____/‾‾‾‾    |
             ⊙    --------- (:2/1,3)--------- (1/2,3) ---------(2:2/3,3)--------- (:1/4,3)---------    ⊙    ---------    ⊙
    c        |                 |                 |                 |                 |                 |                 |
             ⊙    ---------    ⊙    --------- (0/2,2) --------- (1/3,2) ---------(2:2/4,2)---------    ⊙    ---------    ⊙
    a        |    ____/‾‾‾‾    |    ____/‾‾‾‾    |                 |                 |    ____/‾‾‾‾    |    ____/‾‾‾‾    |
             ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙
    a        |    ____/‾‾‾‾    |    ____/‾‾‾‾    |                 |                 |    ____/‾‾‾‾    |    ____/‾‾‾‾    |
             ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙    ---------    ⊙
                      a                 a                 b                 b                 a                 a

The algorithm stopped when it saw the backwards 2-path ending at (1,3) and the forwards 2-path ending at (3,5). The criterion
is a backwards path ending at (u,v) and a forward path ending at (x,y), where u <= x and the two points are on the same
diagonal. (Here the edgegraph has a diagonal, but the criterion is x-y=u-v.) Myers proves there is a forward
2-path from (0,0) to (1,3), and that together with the backwards 2-path ending at (1,3) gives the expected 4-path.
Unfortunately the forward path has to be constructed by another run of the forward algorithm; it can't be found from the
computed labels. That is the worst case. Had the code noticed (x,y)=(u,v)=(3,3) the whole path could be reconstructed
from the edgegraph. The implementation looks for a number of special cases to try to avoid computing an extra forward path.

If the two-sided algorithm has stop early (because D has become too large) it will have found a forward LCS and a
backwards LCS. Ideally these go with disjoint prefixes and suffixes of A and B, but disjointedness may fail and the two
computed LCS may conflict. (An easy example is where A is a suffix of B, and shares a short prefix. The backwards LCS
is all of A, and the forward LCS is a prefix of A.) The algorithm combines the two
to form a best-effort LCS. In the worst case the forward partial LCS may have to
be recomputed.
*/

/* Eugene Myers paper is titled
"An O(ND) Difference Algorithm and Its Variations"
and can be found at
http://www.xmailserver.org/diff2.pdf

(There is a generic implementation of the algorithm the repository with git hash
b9ad7e4ade3a686d608e44475390ad428e60e7fc)
*/


================================================
FILE: internal/diff/lcs/git.sh
================================================
#!/bin/bash
#
# Copyright 2022 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.
#
# Creates a zip file containing all numbered versions
# of the commit history of a large source file, for use
# as input data for the tests of the diff algorithm.
#
# Run script from root of the x/tools repo.

set -eu

# WARNING: This script will install the latest version of $file
# The largest real source file in the x/tools repo.
# file=internal/golang/completion/completion.go
# file=internal/golang/diagnostics.go
file=internal/protocol/tsprotocol.go

tmp=$(mktemp -d)
git log $file |
  awk '/^commit / {print $2}' |
  nl -ba -nrz |
  while read n hash; do
    git checkout --quiet $hash $file
    cp -f $file $tmp/$n
  done
(cd $tmp && zip -q - *) > testdata.zip
rm -fr $tmp
git restore --staged $file
git restore $file
echo "Created testdata.zip"


================================================
FILE: internal/diff/lcs/labels.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

import (
	"fmt"
)

// For each D, vec[D] has length D+1,
// and the label for (D, k) is stored in vec[D][(D+k)/2].
type label struct {
	vec [][]int
}

// Temporary checking DO NOT COMMIT true TO PRODUCTION CODE
const debug = false

// debugging. check that the (d,k) pair is valid
// (that is, -d<=k<=d and d+k even)
func checkDK(D, k int) {
	if k >= -D && k <= D && (D+k)%2 == 0 {
		return
	}
	panic(fmt.Sprintf("out of range, d=%d,k=%d", D, k))
}

func (t *label) set(D, k, x int) {
	if debug {
		checkDK(D, k)
	}
	for len(t.vec) <= D {
		t.vec = append(t.vec, nil)
	}
	if t.vec[D] == nil {
		t.vec[D] = make([]int, D+1)
	}
	t.vec[D][(D+k)/2] = x // known that D+k is even
}

func (t *label) get(d, k int) int {
	if debug {
		checkDK(d, k)
	}
	return int(t.vec[d][(d+k)/2])
}

func newtriang(limit int) label {
	if limit < 100 {
		// Preallocate if limit is not large.
		return label{vec: make([][]int, limit)}
	}
	return label{}
}


================================================
FILE: internal/diff/lcs/old.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

// TODO(adonovan): remove unclear references to "old" in this package.

import (
	"fmt"
)

// A Diff is a replacement of a portion of A by a portion of B.
type Diff struct {
	Start, End         int // offsets of portion to delete in A
	ReplStart, ReplEnd int // offset of replacement text in B
}

// DiffBytes returns the differences between two byte sequences.
// It does not respect rune boundaries.
func DiffBytes(a, b []byte) []Diff { return diff(bytesSeqs{a, b}) }

// DiffRunes returns the differences between two rune sequences.
func DiffRunes(a, b []rune) []Diff { return diff(runesSeqs{a, b}) }

// DiffLines returns the differences between two string sequences.
func DiffLines(a, b []string) []Diff { return diff(linesSeqs{a, b}) }

// A limit on how deeply the LCS algorithm should search. The value is just a guess.
var maxDiffs = 100

func diff(seqs sequences) []Diff {
	diff, _ := compute(seqs, twosided, maxDiffs/2)
	return diff
}

// compute computes the list of differences between two sequences,
// along with the LCS. It is exercised directly by tests.
// The algorithm is one of {forward, backward, twosided}.
func compute(seqs sequences, algo func(*editGraph) lcs, limit int) ([]Diff, lcs) {
	if limit <= 0 {
		limit = 1 << 25 // effectively infinity
	}
	alen, blen := seqs.lengths()
	g := &editGraph{
		seqs:  seqs,
		vf:    newtriang(limit),
		vb:    newtriang(limit),
		limit: limit,
		ux:    alen,
		uy:    blen,
		delta: alen - blen,
	}
	lcs := algo(g)
	diffs := lcs.toDiffs(alen, blen)
	return diffs, lcs
}

// editGraph carries the information for computing the lcs of two sequences.
type editGraph struct {
	seqs   sequences
	vf, vb label // forward and backward labels

	limit int // maximal value of D
	// the bounding rectangle of the current edit graph
	lx, ly, ux, uy int
	delta          int // common subexpression: (ux-lx)-(uy-ly)
}

// toDiffs converts an LCS to a list of edits.
func (lcs lcs) toDiffs(alen, blen int) []Diff {
	var diffs []Diff
	var pa, pb int // offsets in a, b
	for _, l := range lcs {
		if pa < l.X || pb < l.Y {
			diffs = append(diffs, Diff{pa, l.X, pb, l.Y})
		}
		pa = l.X + l.Len
		pb = l.Y + l.Len
	}
	if pa < alen || pb < blen {
		diffs = append(diffs, Diff{pa, alen, pb, blen})
	}
	return diffs
}

// --- FORWARD ---

// fdone decides if the forward path has reached the upper right
// corner of the rectangle. If so, it also returns the computed lcs.
func (e *editGraph) fdone(D, k int) (bool, lcs) {
	// x, y, k are relative to the rectangle
	x := e.vf.get(D, k)
	y := x - k
	if x == e.ux && y == e.uy {
		return true, e.forwardlcs(D, k)
	}
	return false, nil
}

// run the forward algorithm, until success or up to the limit on D.
func forward(e *editGraph) lcs {
	e.setForward(0, 0, e.lx)
	if ok, ans := e.fdone(0, 0); ok {
		return ans
	}
	// from D to D+1
	for D := range e.limit {
		e.setForward(D+1, -(D + 1), e.getForward(D, -D))
		if ok, ans := e.fdone(D+1, -(D + 1)); ok {
			return ans
		}
		e.setForward(D+1, D+1, e.getForward(D, D)+1)
		if ok, ans := e.fdone(D+1, D+1); ok {
			return ans
		}
		for k := -D + 1; k <= D-1; k += 2 {
			// these are tricky and easy to get backwards
			lookv := e.lookForward(k, e.getForward(D, k-1)+1)
			lookh := e.lookForward(k, e.getForward(D, k+1))
			if lookv > lookh {
				e.setForward(D+1, k, lookv)
			} else {
				e.setForward(D+1, k, lookh)
			}
			if ok, ans := e.fdone(D+1, k); ok {
				return ans
			}
		}
	}
	// D is too large
	// find the D path with maximal x+y inside the rectangle and
	// use that to compute the found part of the lcs
	kmax := -e.limit - 1
	diagmax := -1
	for k := -e.limit; k <= e.limit; k += 2 {
		x := e.getForward(e.limit, k)
		y := x - k
		if x+y > diagmax && x <= e.ux && y <= e.uy {
			diagmax, kmax = x+y, k
		}
	}
	return e.forwardlcs(e.limit, kmax)
}

// recover the lcs by backtracking from the farthest point reached
func (e *editGraph) forwardlcs(D, k int) lcs {
	var ans lcs
	for x := e.getForward(D, k); x != 0 || x-k != 0; {
		if ok(D-1, k-1) && x-1 == e.getForward(D-1, k-1) {
			// if (x-1,y) is labelled D-1, x--,D--,k--,continue
			D, k, x = D-1, k-1, x-1
			continue
		} else if ok(D-1, k+1) && x == e.getForward(D-1, k+1) {
			// if (x,y-1) is labelled D-1, x, D--,k++, continue
			D, k = D-1, k+1
			continue
		}
		// if (x-1,y-1)--(x,y) is a diagonal, prepend,x--,y--, continue
		y := x - k
		ans = ans.prepend(x+e.lx-1, y+e.ly-1)
		x--
	}
	return ans
}

// start at (x,y), go up the diagonal as far as possible,
// and label the result with d
func (e *editGraph) lookForward(k, relx int) int {
	rely := relx - k
	x, y := relx+e.lx, rely+e.ly
	if x < e.ux && y < e.uy {
		x += e.seqs.commonPrefixLen(x, e.ux, y, e.uy)
	}
	return x
}

func (e *editGraph) setForward(d, k, relx int) {
	x := e.lookForward(k, relx)
	e.vf.set(d, k, x-e.lx)
}

func (e *editGraph) getForward(d, k int) int {
	x := e.vf.get(d, k)
	return x
}

// --- BACKWARD ---

// bdone decides if the backward path has reached the lower left corner
func (e *editGraph) bdone(D, k int) (bool, lcs) {
	// x, y, k are relative to the rectangle
	x := e.vb.get(D, k)
	y := x - (k + e.delta)
	if x == 0 && y == 0 {
		return true, e.backwardlcs(D, k)
	}
	return false, nil
}

// run the backward algorithm, until success or up to the limit on D.
// (used only by tests)
func backward(e *editGraph) lcs {
	e.setBackward(0, 0, e.ux)
	if ok, ans := e.bdone(0, 0); ok {
		return ans
	}
	// from D to D+1
	for D := range e.limit {
		e.setBackward(D+1, -(D + 1), e.getBackward(D, -D)-1)
		if ok, ans := e.bdone(D+1, -(D + 1)); ok {
			return ans
		}
		e.setBackward(D+1, D+1, e.getBackward(D, D))
		if ok, ans := e.bdone(D+1, D+1); ok {
			return ans
		}
		for k := -D + 1; k <= D-1; k += 2 {
			// these are tricky and easy to get wrong
			lookv := e.lookBackward(k, e.getBackward(D, k-1))
			lookh := e.lookBackward(k, e.getBackward(D, k+1)-1)
			if lookv < lookh {
				e.setBackward(D+1, k, lookv)
			} else {
				e.setBackward(D+1, k, lookh)
			}
			if ok, ans := e.bdone(D+1, k); ok {
				return ans
			}
		}
	}

	// D is too large
	// find the D path with minimal x+y inside the rectangle and
	// use that to compute the part of the lcs found
	kmax := -e.limit - 1
	diagmin := 1 << 25
	for k := -e.limit; k <= e.limit; k += 2 {
		x := e.getBackward(e.limit, k)
		y := x - (k + e.delta)
		if x+y < diagmin && x >= 0 && y >= 0 {
			diagmin, kmax = x+y, k
		}
	}
	if kmax < -e.limit {
		panic(fmt.Sprintf("no paths when limit=%d?", e.limit))
	}
	return e.backwardlcs(e.limit, kmax)
}

// recover the lcs by backtracking
func (e *editGraph) backwardlcs(D, k int) lcs {
	var ans lcs
	for x := e.getBackward(D, k); x != e.ux || x-(k+e.delta) != e.uy; {
		if ok(D-1, k-1) && x == e.getBackward(D-1, k-1) {
			// D--, k--, x unchanged
			D, k = D-1, k-1
			continue
		} else if ok(D-1, k+1) && x+1 == e.getBackward(D-1, k+1) {
			// D--, k++, x++
			D, k, x = D-1, k+1, x+1
			continue
		}
		y := x - (k + e.delta)
		ans = ans.append(x+e.lx, y+e.ly)
		x++
	}
	return ans
}

// start at (x,y), go down the diagonal as far as possible,
func (e *editGraph) lookBackward(k, relx int) int {
	rely := relx - (k + e.delta) // forward k = k + e.delta
	x, y := relx+e.lx, rely+e.ly
	if x > 0 && y > 0 {
		x -= e.seqs.commonSuffixLen(0, x, 0, y)
	}
	return x
}

// convert to rectangle, and label the result with d
func (e *editGraph) setBackward(d, k, relx int) {
	x := e.lookBackward(k, relx)
	e.vb.set(d, k, x-e.lx)
}

func (e *editGraph) getBackward(d, k int) int {
	x := e.vb.get(d, k)
	return x
}

// -- TWOSIDED ---

func twosided(e *editGraph) lcs {
	// The termination condition could be improved, as either the forward
	// or backward pass could succeed before Myers' Lemma applies.
	// Aside from questions of efficiency (is the extra testing cost-effective)
	// this is more likely to matter when e.limit is reached.
	e.setForward(0, 0, e.lx)
	e.setBackward(0, 0, e.ux)

	// from D to D+1
	for D := range e.limit {
		// just finished a backwards pass, so check
		if got, ok := e.twoDone(D, D); ok {
			return e.twolcs(D, D, got)
		}
		// do a forwards pass (D to D+1)
		e.setForward(D+1, -(D + 1), e.getForward(D, -D))
		e.setForward(D+1, D+1, e.getForward(D, D)+1)
		for k := -D + 1; k <= D-1; k += 2 {
			// these are tricky and easy to get backwards
			lookv := e.lookForward(k, e.getForward(D, k-1)+1)
			lookh := e.lookForward(k, e.getForward(D, k+1))
			if lookv > lookh {
				e.setForward(D+1, k, lookv)
			} else {
				e.setForward(D+1, k, lookh)
			}
		}
		// just did a forward pass, so check
		if got, ok := e.twoDone(D+1, D); ok {
			return e.twolcs(D+1, D, got)
		}
		// do a backward pass, D to D+1
		e.setBackward(D+1, -(D + 1), e.getBackward(D, -D)-1)
		e.setBackward(D+1, D+1, e.getBackward(D, D))
		for k := -D + 1; k <= D-1; k += 2 {
			// these are tricky and easy to get wrong
			lookv := e.lookBackward(k, e.getBackward(D, k-1))
			lookh := e.lookBackward(k, e.getBackward(D, k+1)-1)
			if lookv < lookh {
				e.setBackward(D+1, k, lookv)
			} else {
				e.setBackward(D+1, k, lookh)
			}
		}
	}

	// D too large. combine a forward and backward partial lcs
	// first, a forward one
	kmax := -e.limit - 1
	diagmax := -1
	for k := -e.limit; k <= e.limit; k += 2 {
		x := e.getForward(e.limit, k)
		y := x - k
		if x+y > diagmax && x <= e.ux && y <= e.uy {
			diagmax, kmax = x+y, k
		}
	}
	if kmax < -e.limit {
		panic(fmt.Sprintf("no forward paths when limit=%d?", e.limit))
	}
	lcs := e.forwardlcs(e.limit, kmax)
	// now a backward one
	// find the D path with minimal x+y inside the rectangle and
	// use that to compute the lcs
	diagmin := 1 << 25 // infinity
	for k := -e.limit; k <= e.limit; k += 2 {
		x := e.getBackward(e.limit, k)
		y := x - (k + e.delta)
		if x+y < diagmin && x >= 0 && y >= 0 {
			diagmin, kmax = x+y, k
		}
	}
	if kmax < -e.limit {
		panic(fmt.Sprintf("no backward paths when limit=%d?", e.limit))
	}
	lcs = append(lcs, e.backwardlcs(e.limit, kmax)...)
	// These may overlap (e.forwardlcs and e.backwardlcs return sorted lcs)
	ans := lcs.fix()
	return ans
}

// Does Myers' Lemma apply?
func (e *editGraph) twoDone(df, db int) (int, bool) {
	if (df+db+e.delta)%2 != 0 {
		return 0, false // diagonals cannot overlap
	}
	kmin := max(-df, -db+e.delta)
	kmax := min(df, db+e.delta)
	for k := kmin; k <= kmax; k += 2 {
		x := e.vf.get(df, k)
		u := e.vb.get(db, k-e.delta)
		if u <= x {
			// is it worth looking at all the other k?
			for l := k; l <= kmax; l += 2 {
				x := e.vf.get(df, l)
				y := x - l
				u := e.vb.get(db, l-e.delta)
				v := u - l
				if x == u || u == 0 || v == 0 || y == e.uy || x == e.ux {
					return l, true
				}
			}
			return k, true
		}
	}
	return 0, false
}

func (e *editGraph) twolcs(df, db, kf int) lcs {
	// db==df || db+1==df
	x := e.vf.get(df, kf)
	y := x - kf
	kb := kf - e.delta
	u := e.vb.get(db, kb)
	v := u - kf

	// Myers proved there is a df-path from (0,0) to (u,v)
	// and a db-path from (x,y) to (N,M).
	// In the first case the overall path is the forward path
	// to (u,v) followed by the backward path to (N,M).
	// In the second case the path is the backward path to (x,y)
	// followed by the forward path to (x,y) from (0,0).

	// Look for some special cases to avoid computing either of these paths.
	if x == u {
		// "babaab" "cccaba"
		// already patched together
		lcs := e.forwardlcs(df, kf)
		lcs = append(lcs, e.backwardlcs(db, kb)...)
		return lcs.sort()
	}

	// is (u-1,v) or (u,v-1) labelled df-1?
	// if so, that forward df-1-path plus a horizontal or vertical edge
	// is the df-path to (u,v), then plus the db-path to (N,M)
	if u > 0 && ok(df-1, u-1-v) && e.vf.get(df-1, u-1-v) == u-1 {
		//  "aabbab" "cbcabc"
		lcs := e.forwardlcs(df-1, u-1-v)
		lcs = append(lcs, e.backwardlcs(db, kb)...)
		return lcs.sort()
	}
	if v > 0 && ok(df-1, (u-(v-1))) && e.vf.get(df-1, u-(v-1)) == u {
		//  "abaabb" "bcacab"
		lcs := e.forwardlcs(df-1, u-(v-1))
		lcs = append(lcs, e.backwardlcs(db, kb)...)
		return lcs.sort()
	}

	// The path can't possibly contribute to the lcs because it
	// is all horizontal or vertical edges
	if u == 0 || v == 0 || x == e.ux || y == e.uy {
		// "abaabb" "abaaaa"
		if u == 0 || v == 0 {
			return e.backwardlcs(db, kb)
		}
		return e.forwardlcs(df, kf)
	}

	// is (x+1,y) or (x,y+1) labelled db-1?
	if x+1 <= e.ux && ok(db-1, x+1-y-e.delta) && e.vb.get(db-1, x+1-y-e.delta) == x+1 {
		// "bababb" "baaabb"
		lcs := e.backwardlcs(db-1, kb+1)
		lcs = append(lcs, e.forwardlcs(df, kf)...)
		return lcs.sort()
	}
	if y+1 <= e.uy && ok(db-1, x-(y+1)-e.delta) && e.vb.get(db-1, x-(y+1)-e.delta) == x {
		// "abbbaa" "cabacc"
		lcs := e.backwardlcs(db-1, kb-1)
		lcs = append(lcs, e.forwardlcs(df, kf)...)
		return lcs.sort()
	}

	// need to compute another path
	// "aabbaa" "aacaba"
	lcs := e.backwardlcs(db, kb)
	oldx, oldy := e.ux, e.uy
	e.ux = u
	e.uy = v
	lcs = append(lcs, forward(e)...)
	e.ux, e.uy = oldx, oldy
	return lcs.sort()
}


================================================
FILE: internal/diff/lcs/old_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

import (
	"fmt"
	"log"
	"math/rand/v2"
	"os"
	"strings"
	"testing"
)

func TestAlgosOld(t *testing.T) {
	for i, algo := range []func(*editGraph) lcs{forward, backward, twosided} {
		t.Run(strings.Fields("forward backward twosided")[i], func(t *testing.T) {
			for _, tx := range Btests {
				lim := len(tx.a) + len(tx.b)

				diffs, lcs := compute(stringSeqs{tx.a, tx.b}, algo, lim)
				check(t, tx.a, lcs, tx.lcs)
				checkDiffs(t, tx.a, diffs, tx.b)

				diffs, lcs = compute(stringSeqs{tx.b, tx.a}, algo, lim)
				check(t, tx.b, lcs, tx.lcs)
				checkDiffs(t, tx.b, diffs, tx.a)
			}
		})
	}
}

func TestIntOld(t *testing.T) {
	// need to avoid any characters in btests
	lfill, rfill := "AAAAAAAAAAAA", "BBBBBBBBBBBB"
	for _, tx := range Btests {
		if len(tx.a) < 2 || len(tx.b) < 2 {
			continue
		}
		left := tx.a + lfill
		right := tx.b + rfill
		lim := len(tx.a) + len(tx.b)
		diffs, lcs := compute(stringSeqs{left, right}, twosided, lim)
		check(t, left, lcs, tx.lcs)
		checkDiffs(t, left, diffs, right)
		diffs, lcs = compute(stringSeqs{right, left}, twosided, lim)
		check(t, right, lcs, tx.lcs)
		checkDiffs(t, right, diffs, left)

		left = lfill + tx.a
		right = rfill + tx.b
		diffs, lcs = compute(stringSeqs{left, right}, twosided, lim)
		check(t, left, lcs, tx.lcs)
		checkDiffs(t, left, diffs, right)
		diffs, lcs = compute(stringSeqs{right, left}, twosided, lim)
		check(t, right, lcs, tx.lcs)
		checkDiffs(t, right, diffs, left)
	}
}

func TestSpecialOld(t *testing.T) { // exercises lcs.fix
	a := "golang.org/x/tools/intern"
	b := "github.com/google/safehtml/template\"\n\t\"golang.org/x/tools/intern"
	diffs, lcs := compute(stringSeqs{a, b}, twosided, 4)
	if !lcs.valid() {
		t.Errorf("%d,%v", len(diffs), lcs)
	}
}

func TestRegressionOld001(t *testing.T) {
	a := "// Copyright 2019 The Go Authors. All rights reserved.\n// Use of this source code is governed by a BSD-style\n// license that can be found in the LICENSE file.\n\npackage diff_test\n\nimport (\n\t\"fmt\"\n\t\"math/rand\"\n\t\"strings\"\n\t\"testing\"\n\n\t\"golang.org/x/tools/gopls/internal/lsp/diff\"\n\t\"golang.org/x/tools/internal/diff/difftest\"\n\t\"golang.org/x/tools/gopls/internal/span\"\n)\n"

	b := "// Copyright 2019 The Go Authors. All rights reserved.\n// Use of this source code is governed by a BSD-style\n// license that can be found in the LICENSE file.\n\npackage diff_test\n\nimport (\n\t\"fmt\"\n\t\"math/rand\"\n\t\"strings\"\n\t\"testing\"\n\n\t\"github.com/google/safehtml/template\"\n\t\"golang.org/x/tools/gopls/internal/lsp/diff\"\n\t\"golang.org/x/tools/internal/diff/difftest\"\n\t\"golang.org/x/tools/gopls/internal/span\"\n)\n"
	for i := 1; i < len(b); i++ {
		diffs, lcs := compute(stringSeqs{a, b}, twosided, i) // 14 from gopls
		if !lcs.valid() {
			t.Errorf("%d,%v", len(diffs), lcs)
		}
		checkDiffs(t, a, diffs, b)
	}
}

func TestRegressionOld002(t *testing.T) {
	a := "n\"\n)\n"
	b := "n\"\n\t\"golang.org/x//nnal/stack\"\n)\n"
	for i := 1; i <= len(b); i++ {
		diffs, lcs := compute(stringSeqs{a, b}, twosided, i)
		if !lcs.valid() {
			t.Errorf("%d,%v", len(diffs), lcs)
		}
		checkDiffs(t, a, diffs, b)
	}
}

func TestRegressionOld003(t *testing.T) {
	a := "golang.org/x/hello v1.0.0\nrequire golang.org/x/unused v1"
	b := "golang.org/x/hello v1"
	for i := 1; i <= len(a); i++ {
		diffs, lcs := compute(stringSeqs{a, b}, twosided, i)
		if !lcs.valid() {
			t.Errorf("%d,%v", len(diffs), lcs)
		}
		checkDiffs(t, a, diffs, b)
	}
}

func TestRandOld(t *testing.T) {
	rng := rng(t)

	for i := range 1000 {
		// TODO(adonovan): use ASCII and bytesSeqs here? The use of
		// non-ASCII isn't relevant to the property exercised by the test.
		a := []rune(randstr(rng, "abω", 16))
		b := []rune(randstr(rng, "abωc", 16))
		seq := runesSeqs{a, b}

		const lim = 0 // make sure we get the lcs (24 was too small)
		_, forw := compute(seq, forward, lim)
		_, back := compute(seq, backward, lim)
		_, two := compute(seq, twosided, lim)
		if lcslen(two) != lcslen(forw) || lcslen(forw) != lcslen(back) {
			t.Logf("\n%v\n%v\n%v", forw, back, two)
			t.Fatalf("%d forw:%d back:%d two:%d", i, lcslen(forw), lcslen(back), lcslen(two))
		}
		if !two.valid() || !forw.valid() || !back.valid() {
			t.Errorf("check failure")
		}
	}
}

// TestDiffAPI tests the public API functions (Diff{Bytes,Strings,Runes})
// to ensure at least minimal parity of the three representations.
func TestDiffAPI(t *testing.T) {
	for _, test := range []struct {
		a, b                 string
		wantBytes, wantRunes string
	}{
		{"abcXdef", "abcxdef", "[{3 4 3 4}]", "[{3 4 3 4}]"}, // ASCII
		{"abcωdef", "abcΩdef", "[{3 5 3 5}]", "[{3 4 3 4}]"}, // non-ASCII
	} {

		gotBytes := fmt.Sprint(DiffBytes([]byte(test.a), []byte(test.b)))
		if gotBytes != test.wantBytes {
			t.Errorf("DiffBytes(%q, %q) = %v, want %v",
				test.a, test.b, gotBytes, test.wantBytes)
		}
		gotRunes := fmt.Sprint(DiffRunes([]rune(test.a), []rune(test.b)))
		if gotRunes != test.wantRunes {
			t.Errorf("DiffRunes(%q, %q) = %v, want %v",
				test.a, test.b, gotRunes, test.wantRunes)
		}
	}
}

func BenchmarkTwoOld(b *testing.B) {
	tests := genBench(rng(b), "abc", 96)
	for b.Loop() {
		for _, tt := range tests {
			_, two := compute(stringSeqs{tt.before, tt.after}, twosided, 100)
			if !two.valid() {
				b.Error("check failed")
			}
		}
	}
}

func BenchmarkForwOld(b *testing.B) {
	tests := genBench(rng(b), "abc", 96)
	for b.Loop() {
		for _, tt := range tests {
			_, two := compute(stringSeqs{tt.before, tt.after}, forward, 100)
			if !two.valid() {
				b.Error("check failed")
			}
		}
	}
}

// rng returns a randomly initialized PRNG whose seeds are logged so
// that occasional test failures can be deterministically replayed.
func rng(tb testing.TB) *rand.Rand {
	seed1, seed2 := rand.Uint64(), rand.Uint64()
	tb.Logf("PRNG seeds: %d, %d", seed1, seed2)
	return rand.New(rand.NewPCG(seed1, seed2))
}

func genBench(rng *rand.Rand, set string, n int) []struct{ before, after string } {
	// before and after for benchmarks. 24 strings of length n with
	// before and after differing at least once, and about 5%
	var ans []struct{ before, after string }
	for range 24 {
		// maybe b should have an approximately known number of diffs
		a := randstr(rng, set, n)
		cnt := 0
		bb := make([]rune, 0, n)
		for _, r := range a {
			if rand.Float64() < .05 {
				cnt++
				r = 'N'
			}
			bb = append(bb, r)
		}
		if cnt == 0 {
			// avoid == shortcut
			bb[n/2] = 'N'
		}
		ans = append(ans, struct{ before, after string }{a, string(bb)})
	}
	return ans
}

// This benchmark represents a common case for a diff command:
// large file with a single relatively small diff in the middle.
// (It's not clear whether this is representative of gopls workloads
// or whether it is important to gopls diff performance.)
//
// TODO(adonovan) opt: it could be much faster.  For example,
// comparing a file against itself is about 10x faster than with the
// small deletion in the middle. Strangely, comparing a file against
// itself minus the last byte is faster still; I don't know why.
// There is much low-hanging fruit here for further improvement.
func BenchmarkLargeFileSmallDiff(b *testing.B) {
	data, err := os.ReadFile("old.go") // large file
	if err != nil {
		log.Fatal(err)
	}

	n := len(data)

	src := string(data)
	dst := src[:n*49/100] + src[n*51/100:] // remove 2% from the middle
	b.Run("string", func(b *testing.B) {
		for b.Loop() {
			compute(stringSeqs{src, dst}, twosided, len(src)+len(dst))
		}
	})

	srcBytes := []byte(src)
	dstBytes := []byte(dst)
	b.Run("bytes", func(b *testing.B) {
		for b.Loop() {
			compute(bytesSeqs{srcBytes, dstBytes}, twosided, len(srcBytes)+len(dstBytes))
		}
	})

	srcRunes := []rune(src)
	dstRunes := []rune(dst)
	b.Run("runes", func(b *testing.B) {
		for b.Loop() {
			compute(runesSeqs{srcRunes, dstRunes}, twosided, len(srcRunes)+len(dstRunes))
		}
	})
	srcLines := strings.Split(src, "\n")
	dstLines := strings.Split(dst, "\n")
	b.Run("lines", func(b *testing.B) {
		for b.Loop() {
			compute(linesSeqs{srcLines, dstLines}, twosided, len(srcLines)+len(dstLines))
		}
	})
}


================================================
FILE: internal/diff/lcs/sequence.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package lcs

// This file defines the abstract sequence over which the LCS algorithm operates.

// sequences abstracts a pair of sequences, A and B.
type sequences interface {
	lengths() (int, int)                    // len(A), len(B)
	commonPrefixLen(ai, aj, bi, bj int) int // len(commonPrefix(A[ai:aj], B[bi:bj]))
	commonSuffixLen(ai, aj, bi, bj int) int // len(commonSuffix(A[ai:aj], B[bi:bj]))
}

// The explicit capacity in s[i:j:j] leads to more efficient code.

type bytesSeqs struct{ a, b []byte }

func (s bytesSeqs) lengths() (int, int) { return len(s.a), len(s.b) }
func (s bytesSeqs) commonPrefixLen(ai, aj, bi, bj int) int {
	return commonPrefixLen(s.a[ai:aj:aj], s.b[bi:bj:bj])
}
func (s bytesSeqs) commonSuffixLen(ai, aj, bi, bj int) int {
	return commonSuffixLen(s.a[ai:aj:aj], s.b[bi:bj:bj])
}

type runesSeqs struct{ a, b []rune }

func (s runesSeqs) lengths() (int, int) { return len(s.a), len(s.b) }
func (s runesSeqs) commonPrefixLen(ai, aj, bi, bj int) int {
	return commonPrefixLen(s.a[ai:aj:aj], s.b[bi:bj:bj])
}
func (s runesSeqs) commonSuffixLen(ai, aj, bi, bj int) int {
	return commonSuffixLen(s.a[ai:aj:aj], s.b[bi:bj:bj])
}

type linesSeqs struct{ a, b []string }

func (s linesSeqs) lengths() (int, int) { return len(s.a), len(s.b) }
func (s linesSeqs) commonPrefixLen(ai, aj, bi, bj int) int {
	return commonPrefixLen(s.a[ai:aj], s.b[bi:bj])
}
func (s linesSeqs) commonSuffixLen(ai, aj, bi, bj int) int {
	return commonSuffixLen(s.a[ai:aj], s.b[bi:bj])
}

// TODO(adonovan): optimize these functions using ideas from:
// - https://go.dev/cl/408116 common.go
// - https://go.dev/cl/421435 xor_generic.go

// commonPrefixLen returns the length of the common prefix of a[ai:aj] and b[bi:bj].
func commonPrefixLen[T comparable](a, b []T) int {
	n := min(len(a), len(b))
	i := 0
	for i < n && a[i] == b[i] {
		i++
	}
	return i
}

// commonSuffixLen returns the length of the common suffix of a[ai:aj] and b[bi:bj].
func commonSuffixLen[T comparable](a, b []T) int {
	n := min(len(a), len(b))
	i := 0
	for i < n && a[len(a)-1-i] == b[len(b)-1-i] {
		i++
	}
	return i
}


================================================
FILE: internal/diff/merge.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff

import (
	"slices"
)

// Merge merges two valid, ordered lists of edits.
// It returns zero if there was a conflict.
//
// If corresponding edits in x and y are identical,
// they are coalesced in the result.
//
// If x and y both provide different insertions at the same point,
// the insertions from x will be first in the result.
//
// TODO(adonovan): this algorithm could be improved, for example by
// working harder to coalesce non-identical edits that share a common
// deletion or common prefix of insertion (see the tests).
// Survey the academic literature for insights.
func Merge(x, y []Edit) ([]Edit, bool) {
	// Make a defensive (premature) copy of the arrays.
	x = slices.Clone(x)
	y = slices.Clone(y)

	var merged []Edit
	add := func(edit Edit) {
		merged = append(merged, edit)
	}
	var xi, yi int
	for xi < len(x) && yi < len(y) {
		px := &x[xi]
		py := &y[yi]

		if *px == *py {
			// x and y are identical: coalesce.
			add(*px)
			xi++
			yi++

		} else if px.End <= py.Start {
			// x is entirely before y,
			// or an insertion at start of y.
			add(*px)
			xi++

		} else if py.End <= px.Start {
			// y is entirely before x,
			// or an insertion at start of x.
			add(*py)
			yi++

		} else if px.Start < py.Start {
			// x is partly before y:
			// split it into a deletion and an edit.
			add(Edit{px.Start, py.Start, ""})
			px.Start = py.Start

		} else if py.Start < px.Start {
			// y is partly before x:
			// split it into a deletion and an edit.
			add(Edit{py.Start, px.Start, ""})
			py.Start = px.Start

		} else {
			// x and y are unequal non-insertions
			// at the same point: conflict.
			return nil, false
		}
	}
	for ; xi < len(x); xi++ {
		add(x[xi])
	}
	for ; yi < len(y); yi++ {
		add(y[yi])
	}
	return merged, true
}


================================================
FILE: internal/diff/merge_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff_test

import (
	"testing"

	"golang.org/x/tools/internal/diff"
)

func TestMerge(t *testing.T) {
	// For convenience, we test Merge using strings, not sequences
	// of edits, though this does put us at the mercy of the diff
	// algorithm.
	for _, test := range []struct {
		base, x, y string
		want       string // "!" => conflict
	}{
		// independent insertions
		{"abcdef", "abXcdef", "abcdeYf", "abXcdeYf"},
		// independent deletions
		{"abcdef", "acdef", "abcdf", "acdf"},
		// colocated insertions (X first)
		{"abcdef", "abcXdef", "abcYdef", "abcXYdef"},
		// colocated identical insertions (coalesced)
		{"abcdef", "abcXdef", "abcXdef", "abcXdef"},
		// colocated insertions with common prefix (X first)
		// TODO(adonovan): would "abcXYdef" be better?
		// i.e. should we dissect the insertions?
		{"abcdef", "abcXdef", "abcXYdef", "abcXXYdef"},
		// mix of identical and independent insertions (X first)
		{"abcdef", "aIbcdXef", "aIbcdYef", "aIbcdXYef"},
		// independent deletions
		{"abcdef", "def", "abc", ""},
		// overlapping deletions: conflict
		{"abcdef", "adef", "abef", "!"},
		// overlapping deletions with distinct insertions, X first
		{"abcdef", "abXef", "abcYf", "!"},
		// overlapping deletions with distinct insertions, Y first
		{"abcdef", "abcXf", "abYef", "!"},
		// overlapping deletions with common insertions
		{"abcdef", "abXef", "abcXf", "!"},
		// trailing insertions in X (observe X bias)
		{"abcdef", "aXbXcXdXeXfX", "aYbcdef", "aXYbXcXdXeXfX"},
		// trailing insertions in Y (observe X bias)
		{"abcdef", "aXbcdef", "aYbYcYdYeYfY", "aXYbYcYdYeYfY"},
	} {
		dx := diff.Strings(test.base, test.x)
		dy := diff.Strings(test.base, test.y)
		got := "!" // conflict
		if dz, ok := diff.Merge(dx, dy); ok {
			var err error
			got, err = diff.Apply(test.base, dz)
			if err != nil {
				t.Errorf("Merge(%q, %q, %q) produced invalid edits %v: %v", test.base, test.x, test.y, dz, err)
				continue
			}
		}
		if test.want != got {
			t.Errorf("base=%q x=%q y=%q: got %q, want %q", test.base, test.x, test.y, got, test.want)
		}
	}
}


================================================
FILE: internal/diff/ndiff.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff

import (
	"bytes"
	"strings"
	"unicode/utf8"

	"golang.org/x/tools/internal/diff/lcs"
)

// Lines computes differences between two strings. All edits are at line boundaries.
func Lines(before, after string) []Edit {
	beforeLines, bOffsets := splitLines(before)
	afterLines, _ := splitLines(after)
	diffs := lcs.DiffLines(beforeLines, afterLines)

	// Convert from LCS diffs to Edits
	res := make([]Edit, len(diffs))
	for i, d := range diffs {
		res[i] = Edit{
			Start: bOffsets[d.Start],
			End:   bOffsets[d.End],
			New:   strings.Join(afterLines[d.ReplStart:d.ReplEnd], ""),
		}
	}
	return res
}

// Strings computes the differences between two strings.
// The resulting edits respect rune boundaries.
func Strings(before, after string) []Edit {
	if before == after {
		return nil // common case
	}

	if isASCII(before) && isASCII(after) {
		// TODO(adonovan): opt: specialize diffASCII for strings.
		return diffASCII([]byte(before), []byte(after))
	}
	return diffRunes([]rune(before), []rune(after))
}

// Bytes computes the differences between two byte slices.
// The resulting edits respect rune boundaries.
func Bytes(before, after []byte) []Edit {
	if bytes.Equal(before, after) {
		return nil // common case
	}

	if isASCII(before) && isASCII(after) {
		return diffASCII(before, after)
	}
	return diffRunes(runes(before), runes(after))
}

func diffASCII(before, after []byte) []Edit {
	diffs := lcs.DiffBytes(before, after)

	// Convert from LCS diffs.
	res := make([]Edit, len(diffs))
	for i, d := range diffs {
		res[i] = Edit{d.Start, d.End, string(after[d.ReplStart:d.ReplEnd])}
	}
	return res
}

func diffRunes(before, after []rune) []Edit {
	diffs := lcs.DiffRunes(before, after)

	// The diffs returned by the lcs package use indexes
	// into whatever slice was passed in.
	// Convert rune offsets to byte offsets.
	res := make([]Edit, len(diffs))
	lastEnd := 0
	utf8Len := 0
	for i, d := range diffs {
		utf8Len += runesLen(before[lastEnd:d.Start]) // text between edits
		start := utf8Len
		utf8Len += runesLen(before[d.Start:d.End]) // text deleted by this edit
		res[i] = Edit{start, utf8Len, string(after[d.ReplStart:d.ReplEnd])}
		lastEnd = d.End
	}
	return res
}

// runes is like []rune(string(bytes)) without the duplicate allocation.
func runes(bytes []byte) []rune {
	n := utf8.RuneCount(bytes)
	runes := make([]rune, n)
	for i := range n {
		r, sz := utf8.DecodeRune(bytes)
		bytes = bytes[sz:]
		runes[i] = r
	}
	return runes
}

// runesLen returns the length in bytes of the UTF-8 encoding of runes.
func runesLen(runes []rune) (len int) {
	for _, r := range runes {
		len += utf8.RuneLen(r)
	}
	return len
}

// isASCII reports whether s contains only ASCII.
func isASCII[S string | []byte](s S) bool {
	for i := 0; i < len(s); i++ {
		if s[i] >= utf8.RuneSelf {
			return false
		}
	}
	return true
}


================================================
FILE: internal/diff/unified.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diff

import (
	"fmt"
	"log"
	"regexp"
	"strconv"
	"strings"
)

// DefaultContextLines is the number of unchanged lines of surrounding
// context displayed by Unified. Use ToUnified to specify a different value.
const DefaultContextLines = 3

// Unified returns a unified diff of the old and new strings.
// The old and new labels are the names of the old and new files.
// If the strings are equal, it returns the empty string.
func Unified(oldLabel, newLabel, old, new string) string {
	edits := Lines(old, new)
	unified, err := ToUnified(oldLabel, newLabel, old, edits, DefaultContextLines)
	if err != nil {
		// Can't happen: edits are consistent.
		log.Fatalf("internal error in diff.Unified: %v", err)
	}
	return unified
}

// ToUnified applies the edits to content and returns a unified diff,
// with contextLines lines of (unchanged) context around each diff hunk.
// The old and new labels are the names of the content and result files.
// It returns an error if the edits are inconsistent; see ApplyEdits.
func ToUnified(oldLabel, newLabel, content string, edits []Edit, contextLines int) (string, error) {
	u, err := toUnified(oldLabel, newLabel, content, edits, contextLines)
	if err != nil {
		return "", err
	}
	return u.String(), nil
}

// unified represents a set of edits as a unified diff.
type unified struct {
	// from is the name of the original file.
	from string
	// to is the name of the modified file.
	to string
	// hunks is the set of edit hunks needed to transform the file content.
	hunks []*hunk
}

// Hunk represents a contiguous set of line edits to apply.
type hunk struct {
	// The line in the original source where the hunk starts.
	fromLine int
	// The line in the original source where the hunk finishes.
	toLine int
	// The set of line based edits to apply.
	lines []line
}

// Line represents a single line operation to apply as part of a Hunk.
type line struct {
	// kind is the type of line this represents, deletion, insertion or copy.
	kind opKind
	// content is the content of this line.
	// For deletion it is the line being removed, for all others it is the line
	// to put in the output.
	content string
}

// opKind is used to denote the type of operation a line represents.
type opKind int

const (
	// opDelete is the operation kind for a line that is present in the input
	// but not in the output.
	opDelete opKind = iota
	// opInsert is the operation kind for a line that is new in the output.
	opInsert
	// opEqual is the operation kind for a line that is the same in the input and
	// output, often used to provide context around edited lines.
	opEqual
)

// String returns a human readable representation of an OpKind. It is not
// intended for machine processing.
func (k opKind) String() string {
	switch k {
	case opDelete:
		return "delete"
	case opInsert:
		return "insert"
	case opEqual:
		return "equal"
	default:
		panic("unknown operation kind")
	}
}

// toUnified takes a file contents and a sequence of edits, and calculates
// a unified diff that represents those edits.
func toUnified(fromName, toName string, content string, edits []Edit, contextLines int) (unified, error) {
	gap := contextLines * 2
	u := unified{
		from: fromName,
		to:   toName,
	}
	if len(edits) == 0 {
		return u, nil
	}
	var err error
	edits, err = lineEdits(content, edits) // expand to whole lines
	if err != nil {
		return u, err
	}
	lines, _ := splitLines(content)
	var h *hunk
	last := 0
	toLine := 0
	for _, edit := range edits {
		// Compute the zero-based line numbers of the edit start and end.
		// TODO(adonovan): opt: compute incrementally, avoid O(n^2).
		start := strings.Count(content[:edit.Start], "\n")
		end := strings.Count(content[:edit.End], "\n")
		if edit.End == len(content) && len(content) > 0 && content[len(content)-1] != '\n' {
			end++ // EOF counts as an implicit newline
		}

		switch {
		case h != nil && start == last:
			//direct extension
		case h != nil && start <= last+gap:
			//within range of previous lines, add the joiners
			addEqualLines(h, lines, last, start)
		default:
			//need to start a new hunk
			if h != nil {
				// add the edge to the previous hunk
				addEqualLines(h, lines, last, last+contextLines)
				u.hunks = append(u.hunks, h)
			}
			toLine += start - last
			h = &hunk{
				fromLine: start + 1,
				toLine:   toLine + 1,
			}
			// add the edge to the new hunk
			delta := addEqualLines(h, lines, start-contextLines, start)
			h.fromLine -= delta
			h.toLine -= delta
		}
		last = start
		for i := start; i < end; i++ {
			h.lines = append(h.lines, line{kind: opDelete, content: lines[i]})
			last++
		}
		if edit.New != "" {
			v, _ := splitLines(edit.New)
			for _, content := range v {
				h.lines = append(h.lines, line{kind: opInsert, content: content})
				toLine++
			}
		}
	}
	if h != nil {
		// add the edge to the final hunk
		addEqualLines(h, lines, last, last+contextLines)
		u.hunks = append(u.hunks, h)
	}
	return u, nil
}

// split into lines removing a final empty line,
// and also return the offsets of the line beginnings.
func splitLines(text string) ([]string, []int) {
	var lines []string
	offsets := []int{0}
	start := 0
	for i, r := range text {
		if r == '\n' {
			lines = append(lines, text[start:i+1])
			start = i + 1
			offsets = append(offsets, start)
		}
	}
	if start < len(text) {
		lines = append(lines, text[start:])
		offsets = append(offsets, len(text))
	}
	return lines, offsets
}

func addEqualLines(h *hunk, lines []string, start, end int) int {
	delta := 0
	for i := start; i < end; i++ {
		if i < 0 {
			continue
		}
		if i >= len(lines) {
			return delta
		}
		h.lines = append(h.lines, line{kind: opEqual, content: lines[i]})
		delta++
	}
	return delta
}

// String converts a unified diff to the standard textual form for that diff.
// The output of this function can be passed to tools like patch.
func (u unified) String() string {
	if len(u.hunks) == 0 {
		return ""
	}
	b := new(strings.Builder)
	fmt.Fprintf(b, "--- %s\n", u.from)
	fmt.Fprintf(b, "+++ %s\n", u.to)
	for _, hunk := range u.hunks {
		fromCount, toCount := 0, 0
		for _, l := range hunk.lines {
			switch l.kind {
			case opDelete:
				fromCount++
			case opInsert:
				toCount++
			default:
				fromCount++
				toCount++
			}
		}
		fmt.Fprint(b, "@@")
		if fromCount > 1 {
			fmt.Fprintf(b, " -%d,%d", hunk.fromLine, fromCount)
		} else if hunk.fromLine == 1 && fromCount == 0 {
			// Match odd GNU diff -u behavior adding to empty file.
			fmt.Fprintf(b, " -0,0")
		} else {
			fmt.Fprintf(b, " -%d", hunk.fromLine)
		}
		if toCount > 1 {
			fmt.Fprintf(b, " +%d,%d", hunk.toLine, toCount)
		} else if hunk.toLine == 1 && toCount == 0 {
			// Match odd GNU diff -u behavior adding to empty file.
			fmt.Fprintf(b, " +0,0")
		} else {
			fmt.Fprintf(b, " +%d", hunk.toLine)
		}
		fmt.Fprint(b, " @@\n")
		for _, l := range hunk.lines {
			switch l.kind {
			case opDelete:
				fmt.Fprintf(b, "-%s", l.content)
			case opInsert:
				fmt.Fprintf(b, "+%s", l.content)
			default:
				fmt.Fprintf(b, " %s", l.content)
			}
			if !strings.HasSuffix(l.content, "\n") {
				fmt.Fprintf(b, "\n\\ No newline at end of file\n")
			}
		}
	}
	return b.String()
}

// ApplyUnified applies the unified diffs.
func ApplyUnified(udiffs, bef string) (string, error) {
	before := strings.Split(bef, "\n")
	unif := strings.Split(udiffs, "\n")
	var got []string
	left := 0
	// parse and apply the unified diffs
	for _, l := range unif {
		if len(l) == 0 {
			continue // probably the last line (from Split)
		}
		switch l[0] {
		case '@': // The @@ line
			m := atregexp.FindStringSubmatch(l)
			fromLine, err := strconv.Atoi(m[1])
			if err != nil {
				return "", fmt.Errorf("missing line number in %q", l)
			}
			// before is a slice, so0-based; fromLine is 1-based
			for ; left < fromLine-1; left++ {
				got = append(got, before[left])
			}
		case '+': // add this line
			if strings.HasPrefix(l, "+++ ") {
				continue
			}
			got = append(got, l[1:])
		case '-': // delete this line
			if strings.HasPrefix(l, "--- ") {
				continue
			}
			left++
		case ' ':
			return "", fmt.Errorf("unexpected line %q", l)
		default:
			return "", fmt.Errorf("impossible unified %q", udiffs)
		}
	}
	// copy any remaining lines
	for ; left < len(before); left++ {
		got = append(got, before[left])
	}
	return strings.Join(got, "\n"), nil
}

// The first number in the @@ lines is the line number in the 'before' data
var atregexp = regexp.MustCompile(`@@ -(\d+).* @@`)


================================================
FILE: internal/diffp/diff.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package diffp implements a basic diff algorithm equivalent to patience diff.
// It is a copy of internal/diff from the main Go repo, renamed to diffp to avoid
// conflict with the existing golang.org/x/tools/internal/diff.
package diffp

import (
	"bytes"
	"fmt"
	"sort"
	"strings"
)

// A pair is a pair of values tracked for both the x and y side of a diff.
// It is typically a pair of line indexes.
type pair struct{ x, y int }

// Diff returns an anchored diff of the two texts old and new
// in the “unified diff” format. If old and new are identical,
// Diff returns a nil slice (no output).
//
// Unix diff implementations typically look for a diff with
// the smallest number of lines inserted and removed,
// which can in the worst case take time quadratic in the
// number of lines in the texts. As a result, many implementations
// either can be made to run for a long time or cut off the search
// after a predetermined amount of work.
//
// In contrast, this implementation looks for a diff with the
// smallest number of “unique” lines inserted and removed,
// where unique means a line that appears just once in both old and new.
// We call this an “anchored diff” because the unique lines anchor
// the chosen matching regions. An anchored diff is usually clearer
// than a standard diff, because the algorithm does not try to
// reuse unrelated blank lines or closing braces.
// The algorithm also guarantees to run in O(n log n) time
// instead of the standard O(n²) time.
//
// Some systems call this approach a “patience diff,” named for
// the “patience sorting” algorithm, itself named for a solitaire card game.
// We avoid that name for two reasons. First, the name has been used
// for a few different variants of the algorithm, so it is imprecise.
// Second, the name is frequently interpreted as meaning that you have
// to wait longer (to be patient) for the diff, meaning that it is a slower algorithm,
// when in fact the algorithm is faster than the standard one.
func Diff(oldName string, old []byte, newName string, new []byte) []byte {
	if bytes.Equal(old, new) {
		return nil
	}
	x := lines(old)
	y := lines(new)

	// Print diff header.
	var out bytes.Buffer
	fmt.Fprintf(&out, "diff %s %s\n", oldName, newName)
	fmt.Fprintf(&out, "--- %s\n", oldName)
	fmt.Fprintf(&out, "+++ %s\n", newName)

	// Loop over matches to consider,
	// expanding each match to include surrounding lines,
	// and then printing diff chunks.
	// To avoid setup/teardown cases outside the loop,
	// tgs returns a leading {0,0} and trailing {len(x), len(y)} pair
	// in the sequence of matches.
	var (
		done  pair     // printed up to x[:done.x] and y[:done.y]
		chunk pair     // start lines of current chunk
		count pair     // number of lines from each side in current chunk
		ctext []string // lines for current chunk
	)
	for _, m := range tgs(x, y) {
		if m.x < done.x {
			// Already handled scanning forward from earlier match.
			continue
		}

		// Expand matching lines as far possible,
		// establishing that x[start.x:end.x] == y[start.y:end.y].
		// Note that on the first (or last) iteration we may (or definitey do)
		// have an empty match: start.x==end.x and start.y==end.y.
		start := m
		for start.x > done.x && start.y > done.y && x[start.x-1] == y[start.y-1] {
			start.x--
			start.y--
		}
		end := m
		for end.x < len(x) && end.y < len(y) && x[end.x] == y[end.y] {
			end.x++
			end.y++
		}

		// Emit the mismatched lines before start into this chunk.
		// (No effect on first sentinel iteration, when start = {0,0}.)
		for _, s := range x[done.x:start.x] {
			ctext = append(ctext, "-"+s)
			count.x++
		}
		for _, s := range y[done.y:start.y] {
			ctext = append(ctext, "+"+s)
			count.y++
		}

		// If we're not at EOF and have too few common lines,
		// the chunk includes all the common lines and continues.
		const C = 3 // number of context lines
		if (end.x < len(x) || end.y < len(y)) &&
			(end.x-start.x < C || (len(ctext) > 0 && end.x-start.x < 2*C)) {
			for _, s := range x[start.x:end.x] {
				ctext = append(ctext, " "+s)
				count.x++
				count.y++
			}
			done = end
			continue
		}

		// End chunk with common lines for context.
		if len(ctext) > 0 {
			n := min(end.x-start.x, C)
			for _, s := range x[start.x : start.x+n] {
				ctext = append(ctext, " "+s)
				count.x++
				count.y++
			}
			done = pair{start.x + n, start.y + n}

			// Format and emit chunk.
			// Convert line numbers to 1-indexed.
			// Special case: empty file shows up as 0,0 not 1,0.
			if count.x > 0 {
				chunk.x++
			}
			if count.y > 0 {
				chunk.y++
			}
			fmt.Fprintf(&out, "@@ -%d,%d +%d,%d @@\n", chunk.x, count.x, chunk.y, count.y)
			for _, s := range ctext {
				out.WriteString(s)
			}
			count.x = 0
			count.y = 0
			ctext = ctext[:0]
		}

		// If we reached EOF, we're done.
		if end.x >= len(x) && end.y >= len(y) {
			break
		}

		// Otherwise start a new chunk.
		chunk = pair{end.x - C, end.y - C}
		for _, s := range x[chunk.x:end.x] {
			ctext = append(ctext, " "+s)
			count.x++
			count.y++
		}
		done = end
	}

	return out.Bytes()
}

// lines returns the lines in the file x, including newlines.
// If the file does not end in a newline, one is supplied
// along with a warning about the missing newline.
func lines(x []byte) []string {
	l := strings.SplitAfter(string(x), "\n")
	if l[len(l)-1] == "" {
		l = l[:len(l)-1]
	} else {
		// Treat last line as having a message about the missing newline attached,
		// using the same text as BSD/GNU diff (including the leading backslash).
		l[len(l)-1] += "\n\\ No newline at end of file\n"
	}
	return l
}

// tgs returns the pairs of indexes of the longest common subsequence
// of unique lines in x and y, where a unique line is one that appears
// once in x and once in y.
//
// The longest common subsequence algorithm is as described in
// Thomas G. Szymanski, “A Special Case of the Maximal Common
// Subsequence Problem,” Princeton TR #170 (January 1975),
// available at https://research.swtch.com/tgs170.pdf.
func tgs(x, y []string) []pair {
	// Count the number of times each string appears in a and b.
	// We only care about 0, 1, many, counted as 0, -1, -2
	// for the x side and 0, -4, -8 for the y side.
	// Using negative numbers now lets us distinguish positive line numbers later.
	m := make(map[string]int)
	for _, s := range x {
		if c := m[s]; c > -2 {
			m[s] = c - 1
		}
	}
	for _, s := range y {
		if c := m[s]; c > -8 {
			m[s] = c - 4
		}
	}

	// Now unique strings can be identified by m[s] = -1+-4.
	//
	// Gather the indexes of those strings in x and y, building:
	//	xi[i] = increasing indexes of unique strings in x.
	//	yi[i] = increasing indexes of unique strings in y.
	//	inv[i] = index j such that x[xi[i]] = y[yi[j]].
	var xi, yi, inv []int
	for i, s := range y {
		if m[s] == -1+-4 {
			m[s] = len(yi)
			yi = append(yi, i)
		}
	}
	for i, s := range x {
		if j, ok := m[s]; ok && j >= 0 {
			xi = append(xi, i)
			inv = append(inv, j)
		}
	}

	// Apply Algorithm A from Szymanski's paper.
	// In those terms, A = J = inv and B = [0, n).
	// We add sentinel pairs {0,0}, and {len(x),len(y)}
	// to the returned sequence, to help the processing loop.
	J := inv
	n := len(xi)
	T := make([]int, n)
	L := make([]int, n)
	for i := range T {
		T[i] = n + 1
	}
	for i := range n {
		k := sort.Search(n, func(k int) bool {
			return T[k] >= J[i]
		})
		T[k] = J[i]
		L[i] = k + 1
	}
	k := 0
	for _, v := range L {
		if k < v {
			k = v
		}
	}
	seq := make([]pair, 2+k)
	seq[1+k] = pair{len(x), len(y)} // sentinel at end
	lastj := n
	for i := n - 1; i >= 0; i-- {
		if L[i] == k && J[i] < lastj {
			seq[k] = pair{xi[i], yi[J[i]]}
			k--
		}
	}
	seq[0] = pair{0, 0} // sentinel at start
	return seq
}


================================================
FILE: internal/diffp/diff_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package diffp

import (
	"bytes"
	"path/filepath"
	"testing"

	"golang.org/x/tools/txtar"
)

func clean(text []byte) []byte {
	text = bytes.ReplaceAll(text, []byte("$\n"), []byte("\n"))
	text = bytes.TrimSuffix(text, []byte("^D\n"))
	return text
}

func Test(t *testing.T) {
	files, _ := filepath.Glob("testdata/*.txt")
	if len(files) == 0 {
		t.Fatalf("no testdata")
	}

	for _, file := range files {
		t.Run(filepath.Base(file), func(t *testing.T) {
			a, err := txtar.ParseFile(file)
			if err != nil {
				t.Fatal(err)
			}
			if len(a.Files) != 3 || a.Files[2].Name != "diff" {
				t.Fatalf("%s: want three files, third named \"diff\"", file)
			}
			diffs := Diff(a.Files[0].Name, clean(a.Files[0].Data), a.Files[1].Name, clean(a.Files[1].Data))
			want := clean(a.Files[2].Data)
			if !bytes.Equal(diffs, want) {
				t.Fatalf("%s: have:\n%s\nwant:\n%s\n%s", file,
					diffs, want, Diff("have", diffs, "want", want))
			}
		})
	}
}


================================================
FILE: internal/diffp/testdata/allnew.txt
================================================
-- old --
-- new --
a
b
c
-- diff --
diff old new
--- old
+++ new
@@ -0,0 +1,3 @@
+a
+b
+c


================================================
FILE: internal/diffp/testdata/allold.txt
================================================
-- old --
a
b
c
-- new --
-- diff --
diff old new
--- old
+++ new
@@ -1,3 +0,0 @@
-a
-b
-c


================================================
FILE: internal/diffp/testdata/basic.txt
================================================
Example from Hunt and McIlroy, “An Algorithm for Differential File Comparison.”
https://www.cs.dartmouth.edu/~doug/diff.pdf

-- old --
a
b
c
d
e
f
g
-- new --
w
a
b
x
y
z
e
-- diff --
diff old new
--- old
+++ new
@@ -1,7 +1,7 @@
+w
 a
 b
-c
-d
+x
+y
+z
 e
-f
-g


================================================
FILE: internal/diffp/testdata/dups.txt
================================================
-- old --
a

b

c

d

e

f
-- new --
a

B

C

d

e

f
-- diff --
diff old new
--- old
+++ new
@@ -1,8 +1,8 @@
 a
 $
-b
-
-c
+B
+
+C
 $
 d
 $


================================================
FILE: internal/diffp/testdata/end.txt
================================================
-- old --
1
2
3
4
5
6
7
eight
nine
ten
eleven
-- new --
1
2
3
4
5
6
7
8
9
10
-- diff --
diff old new
--- old
+++ new
@@ -5,7 +5,6 @@
 5
 6
 7
-eight
-nine
-ten
-eleven
+8
+9
+10


================================================
FILE: internal/diffp/testdata/eof.txt
================================================
-- old --
a
b
c^D
-- new --
a
b
c^D
-- diff --


================================================
FILE: internal/diffp/testdata/eof1.txt
================================================
-- old --
a
b
c
-- new --
a
b
c^D
-- diff --
diff old new
--- old
+++ new
@@ -1,3 +1,3 @@
 a
 b
-c
+c
\ No newline at end of file


================================================
FILE: internal/diffp/testdata/eof2.txt
================================================
-- old --
a
b
c^D
-- new --
a
b
c
-- diff --
diff old new
--- old
+++ new
@@ -1,3 +1,3 @@
 a
 b
-c
\ No newline at end of file
+c


================================================
FILE: internal/diffp/testdata/long.txt
================================================
-- old --
1
2
3
4
5
6
7
8
9
10
11
12
13
14
14½
15
16
17
18
19
20
-- new --
1
2
3
4
5
6
8
9
10
11
12
13
14
17
18
19
20
-- diff --
diff old new
--- old
+++ new
@@ -4,7 +4,6 @@
 4
 5
 6
-7
 8
 9
 10
@@ -12,9 +11,6 @@
 12
 13
 14
-14½
-15
-16
 17
 18
 19


================================================
FILE: internal/diffp/testdata/same.txt
================================================
-- old --
hello world
-- new --
hello world
-- diff --


================================================
FILE: internal/diffp/testdata/start.txt
================================================
-- old --
e
pi
4
5
6
7
8
9
10
-- new --
1
2
3
4
5
6
7
8
9
10
-- diff --
diff old new
--- old
+++ new
@@ -1,5 +1,6 @@
-e
-pi
+1
+2
+3
 4
 5
 6


================================================
FILE: internal/diffp/testdata/triv.txt
================================================
Another example from Hunt and McIlroy,
“An Algorithm for Differential File Comparison.”
https://www.cs.dartmouth.edu/~doug/diff.pdf

Anchored diff gives up on finding anything,
since there are no unique lines.

-- old --
a
b
c
a
b
b
a
-- new --
c
a
b
a
b
c
-- diff --
diff old new
--- old
+++ new
@@ -1,7 +1,6 @@
-a
-b
-c
-a
-b
-b
-a
+c
+a
+b
+a
+b
+c


================================================
FILE: internal/drivertest/driver.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The drivertest package provides a fake implementation of the go/packages
// driver protocol that delegates to the go list driver. It may be used to test
// programs such as gopls that specialize behavior when a go/packages driver is
// in use.
//
// The driver is run as a child of the current process, by calling [RunIfChild]
// at process start, and running go/packages with the environment variables set
// by [Env].
package drivertest

import (
	"encoding/json"
	"flag"
	"log"
	"os"

	"golang.org/x/tools/go/packages"
)

const runAsDriverEnv = "DRIVERTEST_RUN_AS_DRIVER"

// RunIfChild runs the current process as a go/packages driver, if configured
// to do so by the current environment (see [Env]).
//
// Otherwise, RunIfChild is a no op.
func RunIfChild() {
	if os.Getenv(runAsDriverEnv) != "" {
		main()
		os.Exit(0)
	}
}

// Env returns additional environment variables for use in [packages.Config]
// to enable the use of drivertest as the driver.
//
// t abstracts a *testing.T or log.Default().
func Env(t interface{ Fatal(...any) }) []string {
	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	return []string{"GOPACKAGESDRIVER=" + exe, runAsDriverEnv + "=1"}
}

func main() {
	flag.Parse()

	dec := json.NewDecoder(os.Stdin)
	var request packages.DriverRequest
	if err := dec.Decode(&request); err != nil {
		log.Fatalf("decoding request: %v", err)
	}

	config := packages.Config{
		Mode:       request.Mode,
		Env:        append(request.Env, "GOPACKAGESDRIVER=off"), // avoid recursive invocation
		BuildFlags: request.BuildFlags,
		Tests:      request.Tests,
		Overlay:    request.Overlay,
	}
	pkgs, err := packages.Load(&config, flag.Args()...)
	if err != nil {
		log.Fatalf("load failed: %v", err)
	}

	var roots []string
	for _, pkg := range pkgs {
		roots = append(roots, pkg.ID)
	}
	var allPackages []*packages.Package
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		newImports := make(map[string]*packages.Package)
		for path, imp := range pkg.Imports {
			newImports[path] = &packages.Package{ID: imp.ID}
		}
		pkg.Imports = newImports
		allPackages = append(allPackages, pkg)
	})

	enc := json.NewEncoder(os.Stdout)
	response := packages.DriverResponse{
		Roots:    roots,
		Packages: allPackages,
	}
	if err := enc.Encode(response); err != nil {
		log.Fatalf("encoding response: %v", err)
	}
}


================================================
FILE: internal/drivertest/driver_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package drivertest_test

// This file is both a test of drivertest and an example of how to use it in your own tests.

import (
	"encoding/json"
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/drivertest"
	"golang.org/x/tools/internal/packagesinternal"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

func TestMain(m *testing.M) {
	drivertest.RunIfChild()

	os.Exit(m.Run())
}

func TestDriverConformance(t *testing.T) {
	testenv.NeedsExec(t)

	const workspace = `
-- go.mod --
module example.com/m

go 1.20

-- m.go --
package m

-- lib/lib.go --
package lib
`

	fs, err := txtar.FS(txtar.Parse([]byte(workspace)))
	if err != nil {
		t.Fatal(err)
	}
	dir := testfiles.CopyToTmp(t, fs)

	// TODO(rfindley): on mac, this is required to fix symlink path mismatches.
	// But why? Where is the symlink being evaluated in go/packages?
	dir, err = filepath.EvalSymlinks(dir)
	if err != nil {
		t.Fatal(err)
	}

	baseConfig := packages.Config{
		Dir: dir,
		Mode: packages.NeedName |
			packages.NeedFiles |
			packages.NeedCompiledGoFiles |
			packages.NeedImports |
			packages.NeedDeps |
			packages.NeedTypesSizes |
			packages.NeedModule |
			packages.NeedEmbedFiles |
			packages.LoadMode(packagesinternal.DepsErrors) |
			packages.NeedForTest,
	}

	tests := []struct {
		name    string
		query   string
		overlay string
	}{
		{
			name:  "load all",
			query: "./...",
		},
		{
			name:  "overlays",
			query: "./...",
			overlay: `
-- m.go --
package m

import . "lib"
-- a/a.go --
package a
`,
		},
		{
			name:  "std",
			query: "std",
		},
		{
			name:  "builtin",
			query: "builtin",
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			cfg := baseConfig
			if test.overlay != "" {
				cfg.Overlay = make(map[string][]byte)
				for _, file := range txtar.Parse([]byte(test.overlay)).Files {
					name := filepath.Join(dir, filepath.FromSlash(file.Name))
					cfg.Overlay[name] = file.Data
				}
			}

			// Compare JSON-encoded packages with and without GOPACKAGESDRIVER.
			//
			// Note that this does not guarantee that the go/packages results
			// themselves are equivalent, only that their encoded JSON is equivalent.
			// Certain fields such as Module are intentionally omitted from external
			// drivers, because they don't make sense for an arbitrary build system.
			var jsons []string
			for _, env := range [][]string{
				{"GOPACKAGESDRIVER=off"},
				drivertest.Env(t),
			} {
				cfg.Env = append(os.Environ(), env...)
				pkgs, err := packages.Load(&cfg, test.query)
				if err != nil {
					t.Fatalf("failed to load (env: %v): %v", env, err)
				}
				data, err := json.MarshalIndent(pkgs, "", "\t")
				if err != nil {
					t.Fatalf("failed to marshal (env: %v): %v", env, err)
				}
				jsons = append(jsons, string(data))
			}

			listJSON := jsons[0]
			driverJSON := jsons[1]

			edits := diff.Lines(listJSON, driverJSON)
			d, err := diff.ToUnified("go list", "driver", listJSON, edits, 0)
			if err != nil {
				t.Fatal(err)
			}
			if d != "" {
				t.Errorf("mismatching JSON:\n%s", d)
			}
		})
	}
}


================================================
FILE: internal/edit/edit.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package edit implements buffered position-based editing of byte slices.
package edit

import (
	"fmt"
	"sort"
)

// A Buffer is a queue of edits to apply to a given byte slice.
type Buffer struct {
	old []byte
	q   edits
}

// An edit records a single text modification: change the bytes in [start,end) to new.
type edit struct {
	start int
	end   int
	new   string
}

// An edits is a list of edits that is sortable by start offset, breaking ties by end offset.
type edits []edit

func (x edits) Len() int      { return len(x) }
func (x edits) Swap(i, j int) { x[i], x[j] = x[j], x[i] }
func (x edits) Less(i, j int) bool {
	if x[i].start != x[j].start {
		return x[i].start < x[j].start
	}
	return x[i].end < x[j].end
}

// NewBuffer returns a new buffer to accumulate changes to an initial data slice.
// The returned buffer maintains a reference to the data, so the caller must ensure
// the data is not modified until after the Buffer is done being used.
func NewBuffer(old []byte) *Buffer {
	return &Buffer{old: old}
}

// Insert inserts the new string at old[pos:pos].
func (b *Buffer) Insert(pos int, new string) {
	if pos < 0 || pos > len(b.old) {
		panic("invalid edit position")
	}
	b.q = append(b.q, edit{pos, pos, new})
}

// Delete deletes the text old[start:end].
func (b *Buffer) Delete(start, end int) {
	if end < start || start < 0 || end > len(b.old) {
		panic("invalid edit position")
	}
	b.q = append(b.q, edit{start, end, ""})
}

// Replace replaces old[start:end] with new.
func (b *Buffer) Replace(start, end int, new string) {
	if end < start || start < 0 || end > len(b.old) {
		panic("invalid edit position")
	}
	b.q = append(b.q, edit{start, end, new})
}

// Bytes returns a new byte slice containing the original data
// with the queued edits applied.
func (b *Buffer) Bytes() []byte {
	// Sort edits by starting position and then by ending position.
	// Breaking ties by ending position allows insertions at point x
	// to be applied before a replacement of the text at [x, y).
	sort.Stable(b.q)

	var new []byte
	offset := 0
	for i, e := range b.q {
		if e.start < offset {
			e0 := b.q[i-1]
			panic(fmt.Sprintf("overlapping edits: [%d,%d)->%q, [%d,%d)->%q", e0.start, e0.end, e0.new, e.start, e.end, e.new))
		}
		new = append(new, b.old[offset:e.start]...)
		offset = e.end
		new = append(new, e.new...)
	}
	new = append(new, b.old[offset:]...)
	return new
}

// String returns a string containing the original data
// with the queued edits applied.
func (b *Buffer) String() string {
	return string(b.Bytes())
}


================================================
FILE: internal/edit/edit_test.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package edit

import "testing"

func TestEdit(t *testing.T) {
	b := NewBuffer([]byte("0123456789"))
	b.Insert(8, ",7½,")
	b.Replace(9, 10, "the-end")
	b.Insert(10, "!")
	b.Insert(4, "3.14,")
	b.Insert(4, "π,")
	b.Insert(4, "3.15,")
	b.Replace(3, 4, "three,")
	want := "012three,3.14,π,3.15,4567,7½,8the-end!"

	s := b.String()
	if s != want {
		t.Errorf("b.String() = %q, want %q", s, want)
	}
	sb := b.Bytes()
	if string(sb) != want {
		t.Errorf("b.Bytes() = %q, want %q", sb, want)
	}
}


================================================
FILE: internal/event/bench_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package event_test

import (
	"context"
	"io"
	"log"
	"testing"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

type Hooks struct {
	A func(ctx context.Context, a int) (context.Context, func())
	B func(ctx context.Context, b string) (context.Context, func())
}

var (
	aValue  = keys.NewInt("a", "")
	bValue  = keys.NewString("b", "")
	aCount  = keys.NewInt("aCount", "Count of time A is called.")
	aStat   = keys.NewInt("aValue", "A value.")
	bCount  = keys.NewInt("B", "Count of time B is called.")
	bLength = keys.NewInt("BLen", "B length.")

	Baseline = Hooks{
		A: func(ctx context.Context, a int) (context.Context, func()) {
			return ctx, func() {}
		},
		B: func(ctx context.Context, b string) (context.Context, func()) {
			return ctx, func() {}
		},
	}

	StdLog = Hooks{
		A: func(ctx context.Context, a int) (context.Context, func()) {
			log.Printf("A where a=%d", a)
			return ctx, func() {}
		},
		B: func(ctx context.Context, b string) (context.Context, func()) {
			log.Printf("B where b=%q", b)
			return ctx, func() {}
		},
	}

	Log = Hooks{
		A: func(ctx context.Context, a int) (context.Context, func()) {
			core.Log1(ctx, "A", aValue.Of(a))
			return ctx, func() {}
		},
		B: func(ctx context.Context, b string) (context.Context, func()) {
			core.Log1(ctx, "B", bValue.Of(b))
			return ctx, func() {}
		},
	}

	Trace = Hooks{
		A: func(ctx context.Context, a int) (context.Context, func()) {
			return core.Start1(ctx, "A", aValue.Of(a))
		},
		B: func(ctx context.Context, b string) (context.Context, func()) {
			return core.Start1(ctx, "B", bValue.Of(b))
		},
	}

	Stats = Hooks{
		A: func(ctx context.Context, a int) (context.Context, func()) {
			core.Metric1(ctx, aStat.Of(a))
			core.Metric1(ctx, aCount.Of(1))
			return ctx, func() {}
		},
		B: func(ctx context.Context, b string) (context.Context, func()) {
			core.Metric1(ctx, bLength.Of(len(b)))
			core.Metric1(ctx, bCount.Of(1))
			return ctx, func() {}
		},
	}

	initialList = []int{0, 1, 22, 333, 4444, 55555, 666666, 7777777}
	stringList  = []string{
		"A value",
		"Some other value",
		"A nice longer value but not too long",
		"V",
		"",
		"ı",
		"prime count of values",
	}
)

type namedBenchmark struct {
	name string
	test func(*testing.B)
}

func Benchmark(b *testing.B) {
	b.Run("Baseline", Baseline.runBenchmark)
	b.Run("StdLog", StdLog.runBenchmark)
	benchmarks := []namedBenchmark{
		{"Log", Log.runBenchmark},
		{"Trace", Trace.runBenchmark},
		{"Stats", Stats.runBenchmark},
	}

	event.SetExporter(nil)
	for _, t := range benchmarks {
		b.Run(t.name+"NoExporter", t.test)
	}

	event.SetExporter(noopExporter)
	for _, t := range benchmarks {
		b.Run(t.name+"Noop", t.test)
	}

	event.SetExporter(export.Spans(export.LogWriter(io.Discard, false)))
	for _, t := range benchmarks {
		b.Run(t.name, t.test)
	}
}

func A(ctx context.Context, hooks Hooks, a int) int {
	ctx, done := hooks.A(ctx, a)
	defer done()
	return B(ctx, hooks, a, stringList[a%len(stringList)])
}

func B(ctx context.Context, hooks Hooks, a int, b string) int {
	_, done := hooks.B(ctx, b)
	defer done()
	return a + len(b)
}

func (hooks Hooks) runBenchmark(b *testing.B) {
	ctx := context.Background()
	b.ReportAllocs()

	var acc int
	for b.Loop() {
		for _, value := range initialList {
			acc += A(ctx, hooks, value)
		}
	}
}

func init() {
	log.SetOutput(io.Discard)
}

func noopExporter(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	return ctx
}


================================================
FILE: internal/event/core/event.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package core provides support for event based telemetry.
package core

import (
	"fmt"
	"iter"
	"time"

	"golang.org/x/tools/internal/event/label"
)

// Event holds the information about an event of note that occurred.
type Event struct {
	at time.Time

	// As events are often on the stack, storing the first few labels directly
	// in the event can avoid an allocation at all for the very common cases of
	// simple events.
	// The length needs to be large enough to cope with the majority of events
	// but no so large as to cause undue stack pressure.
	// A log message with two values will use 3 labels (one for each value and
	// one for the message itself).

	static  [3]label.Label // inline storage for the first few labels
	dynamic []label.Label  // dynamically sized storage for remaining labels
}

func (ev Event) At() time.Time { return ev.at }

func (ev Event) Format(f fmt.State, r rune) {
	if !ev.at.IsZero() {
		fmt.Fprint(f, ev.at.Format("2006/01/02 15:04:05 "))
	}
	for l := range ev.Labels() {
		fmt.Fprintf(f, "\n\t%v", l)
	}
}

func (ev Event) Valid(index int) bool {
	return index >= 0 && index < len(ev.static)+len(ev.dynamic)
}

func (ev Event) Label(index int) label.Label {
	if index < len(ev.static) {
		return ev.static[index]
	}
	return ev.dynamic[index-len(ev.static)]
}

// Labels returns an iterator over the event's valid labels.
func (ev Event) Labels() iter.Seq[label.Label] {
	return func(yield func(label.Label) bool) {
		for _, l := range ev.static {
			if l.Valid() && !yield(l) {
				return
			}
		}
		for _, l := range ev.dynamic {
			if l.Valid() && !yield(l) {
				return
			}
		}
	}
}

func (ev Event) Find(key label.Key) label.Label {
	for _, l := range ev.static {
		if l.Key() == key {
			return l
		}
	}
	for _, l := range ev.dynamic {
		if l.Key() == key {
			return l
		}
	}
	return label.Label{}
}

func MakeEvent(static [3]label.Label, labels []label.Label) Event {
	return Event{
		static:  static,
		dynamic: labels,
	}
}

// CloneEvent event returns a copy of the event with the time adjusted to at.
func CloneEvent(ev Event, at time.Time) Event {
	ev.at = at
	return ev
}


================================================
FILE: internal/event/core/export.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package core

import (
	"context"
	"sync/atomic"
	"time"

	"golang.org/x/tools/internal/event/label"
)

// Exporter is a function that handles events.
// It may return a modified context and event.
type Exporter func(context.Context, Event, label.Map) context.Context

var exporter atomic.Pointer[Exporter]

// SetExporter sets the global exporter function that handles all events.
// The exporter is called synchronously from the event call site, so it should
// return quickly so as not to hold up user code.
func SetExporter(e Exporter) {
	if e == nil {
		// &e is always valid, and so p is always valid, but for the early abort
		// of ProcessEvent to be efficient it needs to make the nil check on the
		// pointer without having to dereference it, so we make the nil function
		// also a nil pointer
		exporter.Store(nil)
	} else {
		exporter.Store(&e)
	}
}

// deliver is called to deliver an event to the supplied exporter.
// it will fill in the time.
func deliver(ctx context.Context, exporter Exporter, ev Event) context.Context {
	// add the current time to the event
	ev.at = time.Now()
	// hand the event off to the current exporter
	return exporter(ctx, ev, ev)
}

// Export is called to deliver an event to the global exporter if set.
func Export(ctx context.Context, ev Event) context.Context {
	// get the global exporter and abort early if there is not one
	exporterPtr := exporter.Load()
	if exporterPtr == nil {
		return ctx
	}
	return deliver(ctx, *exporterPtr, ev)
}

// ExportPair is called to deliver a start event to the supplied exporter.
// It also returns a function that will deliver the end event to the same
// exporter.
// It will fill in the time.
func ExportPair(ctx context.Context, begin, end Event) (context.Context, func()) {
	// get the global exporter and abort early if there is not one
	exporterPtr := exporter.Load()
	if exporterPtr == nil {
		return ctx, func() {}
	}
	ctx = deliver(ctx, *exporterPtr, begin)
	return ctx, func() { deliver(ctx, *exporterPtr, end) }
}


================================================
FILE: internal/event/core/fast.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package core

import (
	"context"

	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// Log1 takes a message and one label delivers a log event to the exporter.
// It is a customized version of Print that is faster and does no allocation.
func Log1(ctx context.Context, message string, t1 label.Label) {
	Export(ctx, MakeEvent([3]label.Label{
		keys.Msg.Of(message),
		t1,
	}, nil))
}

// Log2 takes a message and two labels and delivers a log event to the exporter.
// It is a customized version of Print that is faster and does no allocation.
func Log2(ctx context.Context, message string, t1 label.Label, t2 label.Label) {
	Export(ctx, MakeEvent([3]label.Label{
		keys.Msg.Of(message),
		t1,
		t2,
	}, nil))
}

// Metric1 sends a label event to the exporter with the supplied labels.
func Metric1(ctx context.Context, t1 label.Label) context.Context {
	return Export(ctx, MakeEvent([3]label.Label{
		keys.Metric.New(),
		t1,
	}, nil))
}

// Metric2 sends a label event to the exporter with the supplied labels.
func Metric2(ctx context.Context, t1, t2 label.Label) context.Context {
	return Export(ctx, MakeEvent([3]label.Label{
		keys.Metric.New(),
		t1,
		t2,
	}, nil))
}

// Start1 sends a span start event with the supplied label list to the exporter.
// It also returns a function that will end the span, which should normally be
// deferred.
func Start1(ctx context.Context, name string, t1 label.Label) (context.Context, func()) {
	return ExportPair(ctx,
		MakeEvent([3]label.Label{
			keys.Start.Of(name),
			t1,
		}, nil),
		MakeEvent([3]label.Label{
			keys.End.New(),
		}, nil))
}

// Start2 sends a span start event with the supplied label list to the exporter.
// It also returns a function that will end the span, which should normally be
// deferred.
func Start2(ctx context.Context, name string, t1, t2 label.Label) (context.Context, func()) {
	return ExportPair(ctx,
		MakeEvent([3]label.Label{
			keys.Start.Of(name),
			t1,
			t2,
		}, nil),
		MakeEvent([3]label.Label{
			keys.End.New(),
		}, nil))
}


================================================
FILE: internal/event/doc.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package event provides a set of packages that cover the main
// concepts of telemetry in an implementation agnostic way.
package event


================================================
FILE: internal/event/event.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package event

import (
	"context"

	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// Exporter is a function that handles events.
// It may return a modified context and event.
type Exporter func(context.Context, core.Event, label.Map) context.Context

// SetExporter sets the global exporter function that handles all events.
// The exporter is called synchronously from the event call site, so it should
// return quickly so as not to hold up user code.
func SetExporter(e Exporter) {
	core.SetExporter(core.Exporter(e))
}

// Log takes a message and a label list and combines them into a single event
// before delivering them to the exporter.
func Log(ctx context.Context, message string, labels ...label.Label) {
	core.Export(ctx, core.MakeEvent([3]label.Label{
		keys.Msg.Of(message),
	}, labels))
}

// IsLog returns true if the event was built by the Log function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsLog(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Msg
}

// Error takes a message and a label list and combines them into a single event
// before delivering them to the exporter. It captures the error in the
// delivered event.
func Error(ctx context.Context, message string, err error, labels ...label.Label) {
	core.Export(ctx, core.MakeEvent([3]label.Label{
		keys.Msg.Of(message),
		keys.Err.Of(err),
	}, labels))
}

// IsError returns true if the event was built by the Error function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsError(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Msg &&
		ev.Label(1).Key() == keys.Err
}

// Metric sends a label event to the exporter with the supplied labels.
func Metric(ctx context.Context, labels ...label.Label) {
	core.Export(ctx, core.MakeEvent([3]label.Label{
		keys.Metric.New(),
	}, labels))
}

// IsMetric returns true if the event was built by the Metric function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsMetric(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Metric
}

// Label sends a label event to the exporter with the supplied labels.
func Label(ctx context.Context, labels ...label.Label) context.Context {
	return core.Export(ctx, core.MakeEvent([3]label.Label{
		keys.Label.New(),
	}, labels))
}

// IsLabel returns true if the event was built by the Label function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsLabel(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Label
}

// Start sends a span start event with the supplied label list to the exporter.
// It also returns a function that will end the span, which should normally be
// deferred.
func Start(ctx context.Context, name string, labels ...label.Label) (context.Context, func()) {
	return core.ExportPair(ctx,
		core.MakeEvent([3]label.Label{
			keys.Start.Of(name),
		}, labels),
		core.MakeEvent([3]label.Label{
			keys.End.New(),
		}, nil))
}

// IsStart returns true if the event was built by the Start function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsStart(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Start
}

// IsEnd returns true if the event was built by the End function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsEnd(ev core.Event) bool {
	return ev.Label(0).Key() == keys.End
}

// Detach returns a context without an associated span.
// This allows the creation of spans that are not children of the current span.
func Detach(ctx context.Context) context.Context {
	return core.Export(ctx, core.MakeEvent([3]label.Label{
		keys.Detach.New(),
	}, nil))
}

// IsDetach returns true if the event was built by the Detach function.
// It is intended to be used in exporters to identify the semantics of the
// event when deciding what to do with it.
func IsDetach(ev core.Event) bool {
	return ev.Label(0).Key() == keys.Detach
}


================================================
FILE: internal/event/export/eventtest/eventtest.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package eventtest supports logging events to a test.
// You can use NewContext to create a context that knows how to deliver
// telemetry events back to the test.
// You must use this context or a derived one anywhere you want telemetry to be
// correctly routed back to the test it was constructed with.
// Any events delivered to a background context will be dropped.
//
// Importing this package will cause it to register a new global telemetry
// exporter that understands the special contexts returned by NewContext.
// This means you should not import this package if you are not going to call
// NewContext.
package eventtest

import (
	"bytes"
	"context"
	"sync"
	"testing"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/label"
)

func init() {
	e := &testExporter{buffer: &bytes.Buffer{}}
	e.logger = export.LogWriter(e.buffer, false)

	event.SetExporter(export.Spans(e.processEvent))
}

type testingKeyType int

const testingKey = testingKeyType(0)

// NewContext returns a context you should use for the active test.
func NewContext(ctx context.Context, t testing.TB) context.Context {
	return context.WithValue(ctx, testingKey, t)
}

type testExporter struct {
	mu     sync.Mutex
	buffer *bytes.Buffer
	logger event.Exporter
}

func (w *testExporter) processEvent(ctx context.Context, ev core.Event, tm label.Map) context.Context {
	w.mu.Lock()
	defer w.mu.Unlock()
	// build our log message in buffer
	result := w.logger(ctx, ev, tm)
	v := ctx.Value(testingKey)
	// get the testing.TB
	if w.buffer.Len() > 0 && v != nil {
		v.(testing.TB).Log(w.buffer)
	}
	w.buffer.Truncate(0)
	return result
}


================================================
FILE: internal/event/export/id.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export

import (
	crand "crypto/rand"
	"encoding/binary"
	"fmt"
	"math/rand"
	"sync"
	"sync/atomic"
)

type TraceID [16]byte
type SpanID [8]byte

func (t TraceID) String() string {
	return fmt.Sprintf("%02x", t[:])
}

func (s SpanID) String() string {
	return fmt.Sprintf("%02x", s[:])
}

func (s SpanID) IsValid() bool {
	return s != SpanID{}
}

var (
	generationMu sync.Mutex
	nextSpanID   uint64
	spanIDInc    uint64

	traceIDAdd  [2]uint64
	traceIDRand *rand.Rand
)

func initGenerator() {
	var rngSeed int64
	for _, p := range []any{
		&rngSeed, &traceIDAdd, &nextSpanID, &spanIDInc,
	} {
		binary.Read(crand.Reader, binary.LittleEndian, p)
	}
	traceIDRand = rand.New(rand.NewSource(rngSeed))
	spanIDInc |= 1
}

func newTraceID() TraceID {
	generationMu.Lock()
	defer generationMu.Unlock()
	if traceIDRand == nil {
		initGenerator()
	}
	var tid [16]byte
	binary.LittleEndian.PutUint64(tid[0:8], traceIDRand.Uint64()+traceIDAdd[0])
	binary.LittleEndian.PutUint64(tid[8:16], traceIDRand.Uint64()+traceIDAdd[1])
	return tid
}

func newSpanID() SpanID {
	var id uint64
	for id == 0 {
		id = atomic.AddUint64(&nextSpanID, spanIDInc)
	}
	var sid [8]byte
	binary.LittleEndian.PutUint64(sid[:], id)
	return sid
}


================================================
FILE: internal/event/export/labels.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export

import (
	"context"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/label"
)

// Labels builds an exporter that manipulates the context using the event.
// If the event is type IsLabel or IsStartSpan then it returns a context updated
// with label values from the event.
// For all other event types the event labels will be updated with values from the
// context if they are missing.
func Labels(output event.Exporter) event.Exporter {
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		stored, _ := ctx.Value(labelContextKey).(label.Map)
		if event.IsLabel(ev) || event.IsStart(ev) {
			// update the label map stored in the context
			fromEvent := label.Map(ev)
			if stored == nil {
				stored = fromEvent
			} else {
				stored = label.MergeMaps(fromEvent, stored)
			}
			ctx = context.WithValue(ctx, labelContextKey, stored)
		}
		// add the stored label context to the label map
		lm = label.MergeMaps(lm, stored)
		return output(ctx, ev, lm)
	}
}


================================================
FILE: internal/event/export/log.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export

import (
	"context"
	"fmt"
	"io"
	"sync"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/label"
)

// LogWriter returns an Exporter that logs events to the supplied writer.
// If onlyErrors is true it does not log any event that did not have an
// associated error.
// It ignores all telemetry other than log events.
func LogWriter(w io.Writer, onlyErrors bool) event.Exporter {
	lw := &logWriter{writer: w, onlyErrors: onlyErrors}
	return lw.ProcessEvent
}

type logWriter struct {
	mu         sync.Mutex
	printer    Printer
	writer     io.Writer
	onlyErrors bool
}

func (w *logWriter) ProcessEvent(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	switch {
	case event.IsLog(ev):
		if w.onlyErrors && !event.IsError(ev) {
			return ctx
		}
		w.mu.Lock()
		defer w.mu.Unlock()
		w.printer.WriteEvent(w.writer, ev, lm)

	case event.IsStart(ev):
		if span := GetSpan(ctx); span != nil {
			fmt.Fprintf(w.writer, "start: %v %v", span.Name, span.ID)
			if span.ParentID.IsValid() {
				fmt.Fprintf(w.writer, "[%v]", span.ParentID)
			}
		}
	case event.IsEnd(ev):
		if span := GetSpan(ctx); span != nil {
			fmt.Fprintf(w.writer, "finish: %v %v", span.Name, span.ID)
		}
	}
	return ctx
}


================================================
FILE: internal/event/export/log_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export_test

import (
	"context"
	"errors"
	"os"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

func ExampleLog() {
	ctx := context.Background()
	event.SetExporter(timeFixer(export.LogWriter(os.Stdout, false)))
	anInt := keys.NewInt("myInt", "an integer")
	aString := keys.NewString("myString", "a string")
	event.Log(ctx, "my event", anInt.Of(6))
	event.Error(ctx, "error event", errors.New("an error"), aString.Of("some string value"))
	// Output:
	// 2020/03/05 14:27:48 my event
	// 	myInt=6
	// 2020/03/05 14:27:48 error event: an error
	// 	myString="some string value"
}

func timeFixer(output event.Exporter) event.Exporter {
	at, _ := time.Parse(time.RFC3339Nano, "2020-03-05T14:27:48Z")
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		copy := core.CloneEvent(ev, at)
		return output(ctx, copy, lm)
	}
}


================================================
FILE: internal/event/export/metric/data.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package metric

import (
	"fmt"
	"sort"
	"time"

	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// Data represents a single point in the time series of a metric.
// This provides the common interface to all metrics no matter their data
// format.
// To get the actual values for the metric you must type assert to a concrete
// metric type.
type Data interface {
	// Handle returns the metric handle this data is for.
	//TODO: rethink the concept of metric handles
	Handle() string
	// Groups reports the rows that currently exist for this metric.
	Groups() [][]label.Label
}

// Int64Data is a concrete implementation of Data for int64 scalar metrics.
type Int64Data struct {
	// Info holds the original construction information.
	Info *Scalar
	// IsGauge is true for metrics that track values, rather than increasing over time.
	IsGauge bool
	// Rows holds the per group values for the metric.
	Rows []int64
	// EndTime is the last time this metric was updated.
	EndTime time.Time

	groups [][]label.Label
	key    *keys.Int
}

// Float64Data is a concrete implementation of Data for float64 scalar metrics.
type Float64Data struct {
	// Info holds the original construction information.
	Info *Scalar
	// IsGauge is true for metrics that track values, rather than increasing over time.
	IsGauge bool
	// Rows holds the per group values for the metric.
	Rows []float64
	// EndTime is the last time this metric was updated.
	EndTime time.Time

	groups [][]label.Label
	key    *keys.Float
}

// HistogramInt64Data is a concrete implementation of Data for int64 histogram metrics.
type HistogramInt64Data struct {
	// Info holds the original construction information.
	Info *HistogramInt64
	// Rows holds the per group values for the metric.
	Rows []*HistogramInt64Row
	// EndTime is the last time this metric was updated.
	EndTime time.Time

	groups [][]label.Label
	key    *keys.Int
}

// HistogramInt64Row holds the values for a single row of a HistogramInt64Data.
type HistogramInt64Row struct {
	// Values is the counts per bucket.
	Values []int64
	// Count is the total count.
	Count int64
	// Sum is the sum of all the values recorded.
	Sum int64
	// Min is the smallest recorded value.
	Min int64
	// Max is the largest recorded value.
	Max int64
}

// HistogramFloat64Data is a concrete implementation of Data for float64 histogram metrics.
type HistogramFloat64Data struct {
	// Info holds the original construction information.
	Info *HistogramFloat64
	// Rows holds the per group values for the metric.
	Rows []*HistogramFloat64Row
	// EndTime is the last time this metric was updated.
	EndTime time.Time

	groups [][]label.Label
	key    *keys.Float
}

// HistogramFloat64Row holds the values for a single row of a HistogramFloat64Data.
type HistogramFloat64Row struct {
	// Values is the counts per bucket.
	Values []int64
	// Count is the total count.
	Count int64
	// Sum is the sum of all the values recorded.
	Sum float64
	// Min is the smallest recorded value.
	Min float64
	// Max is the largest recorded value.
	Max float64
}

func labelListEqual(a, b []label.Label) bool {
	//TODO: make this more efficient
	return fmt.Sprint(a) == fmt.Sprint(b)
}

func labelListLess(a, b []label.Label) bool {
	//TODO: make this more efficient
	return fmt.Sprint(a) < fmt.Sprint(b)
}

func getGroup(lm label.Map, g *[][]label.Label, keys []label.Key) (int, bool) {
	group := make([]label.Label, len(keys))
	for i, key := range keys {
		l := lm.Find(key)
		if l.Valid() {
			group[i] = l
		}
	}
	old := *g
	index := sort.Search(len(old), func(i int) bool {
		return !labelListLess(old[i], group)
	})
	if index < len(old) && labelListEqual(group, old[index]) {
		// not a new group
		return index, false
	}
	*g = make([][]label.Label, len(old)+1)
	copy(*g, old[:index])
	copy((*g)[index+1:], old[index:])
	(*g)[index] = group
	return index, true
}

func (data *Int64Data) Handle() string          { return data.Info.Name }
func (data *Int64Data) Groups() [][]label.Label { return data.groups }

func (data *Int64Data) modify(at time.Time, lm label.Map, f func(v int64) int64) Data {
	index, insert := getGroup(lm, &data.groups, data.Info.Keys)
	old := data.Rows
	if insert {
		data.Rows = make([]int64, len(old)+1)
		copy(data.Rows, old[:index])
		copy(data.Rows[index+1:], old[index:])
	} else {
		data.Rows = make([]int64, len(old))
		copy(data.Rows, old)
	}
	data.Rows[index] = f(data.Rows[index])
	data.EndTime = at
	frozen := *data
	return &frozen
}

func (data *Int64Data) count(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v int64) int64 {
		return v + 1
	})
}

func (data *Int64Data) sum(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v int64) int64 {
		return v + data.key.From(l)
	})
}

func (data *Int64Data) latest(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v int64) int64 {
		return data.key.From(l)
	})
}

func (data *Float64Data) Handle() string          { return data.Info.Name }
func (data *Float64Data) Groups() [][]label.Label { return data.groups }

func (data *Float64Data) modify(at time.Time, lm label.Map, f func(v float64) float64) Data {
	index, insert := getGroup(lm, &data.groups, data.Info.Keys)
	old := data.Rows
	if insert {
		data.Rows = make([]float64, len(old)+1)
		copy(data.Rows, old[:index])
		copy(data.Rows[index+1:], old[index:])
	} else {
		data.Rows = make([]float64, len(old))
		copy(data.Rows, old)
	}
	data.Rows[index] = f(data.Rows[index])
	data.EndTime = at
	frozen := *data
	return &frozen
}

func (data *Float64Data) sum(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v float64) float64 {
		return v + data.key.From(l)
	})
}

func (data *Float64Data) latest(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v float64) float64 {
		return data.key.From(l)
	})
}

func (data *HistogramInt64Data) Handle() string          { return data.Info.Name }
func (data *HistogramInt64Data) Groups() [][]label.Label { return data.groups }

func (data *HistogramInt64Data) modify(at time.Time, lm label.Map, f func(v *HistogramInt64Row)) Data {
	index, insert := getGroup(lm, &data.groups, data.Info.Keys)
	old := data.Rows
	var v HistogramInt64Row
	if insert {
		data.Rows = make([]*HistogramInt64Row, len(old)+1)
		copy(data.Rows, old[:index])
		copy(data.Rows[index+1:], old[index:])
	} else {
		data.Rows = make([]*HistogramInt64Row, len(old))
		copy(data.Rows, old)
		v = *data.Rows[index]
	}
	oldValues := v.Values
	v.Values = make([]int64, len(data.Info.Buckets))
	copy(v.Values, oldValues)
	f(&v)
	data.Rows[index] = &v
	data.EndTime = at
	frozen := *data
	return &frozen
}

func (data *HistogramInt64Data) record(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v *HistogramInt64Row) {
		value := data.key.From(l)
		v.Sum += value
		if v.Min > value || v.Count == 0 {
			v.Min = value
		}
		if v.Max < value || v.Count == 0 {
			v.Max = value
		}
		v.Count++
		for i, b := range data.Info.Buckets {
			if value <= b {
				v.Values[i]++
			}
		}
	})
}

func (data *HistogramFloat64Data) Handle() string          { return data.Info.Name }
func (data *HistogramFloat64Data) Groups() [][]label.Label { return data.groups }

func (data *HistogramFloat64Data) modify(at time.Time, lm label.Map, f func(v *HistogramFloat64Row)) Data {
	index, insert := getGroup(lm, &data.groups, data.Info.Keys)
	old := data.Rows
	var v HistogramFloat64Row
	if insert {
		data.Rows = make([]*HistogramFloat64Row, len(old)+1)
		copy(data.Rows, old[:index])
		copy(data.Rows[index+1:], old[index:])
	} else {
		data.Rows = make([]*HistogramFloat64Row, len(old))
		copy(data.Rows, old)
		v = *data.Rows[index]
	}
	oldValues := v.Values
	v.Values = make([]int64, len(data.Info.Buckets))
	copy(v.Values, oldValues)
	f(&v)
	data.Rows[index] = &v
	data.EndTime = at
	frozen := *data
	return &frozen
}

func (data *HistogramFloat64Data) record(at time.Time, lm label.Map, l label.Label) Data {
	return data.modify(at, lm, func(v *HistogramFloat64Row) {
		value := data.key.From(l)
		v.Sum += value
		if v.Min > value || v.Count == 0 {
			v.Min = value
		}
		if v.Max < value || v.Count == 0 {
			v.Max = value
		}
		v.Count++
		for i, b := range data.Info.Buckets {
			if value <= b {
				v.Values[i]++
			}
		}
	})
}


================================================
FILE: internal/event/export/metric/exporter.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package metric aggregates events into metrics that can be exported.
package metric

import (
	"context"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

var Entries = keys.New("metric_entries", "The set of metrics calculated for an event")

type Config struct {
	subscribers map[any][]subscriber
}

type subscriber func(time.Time, label.Map, label.Label) Data

func (e *Config) subscribe(key label.Key, s subscriber) {
	if e.subscribers == nil {
		e.subscribers = make(map[any][]subscriber)
	}
	e.subscribers[key] = append(e.subscribers[key], s)
}

func (e *Config) Exporter(output event.Exporter) event.Exporter {
	var mu sync.Mutex
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		if !event.IsMetric(ev) {
			return output(ctx, ev, lm)
		}
		mu.Lock()
		defer mu.Unlock()
		var metrics []Data
		for l := range ev.Labels() {
			id := l.Key()
			if list := e.subscribers[id]; len(list) > 0 {
				for _, s := range list {
					metrics = append(metrics, s(ev.At(), lm, l))
				}
			}
		}
		lm = label.MergeMaps(label.NewMap(Entries.Of(metrics)), lm)
		return output(ctx, ev, lm)
	}
}


================================================
FILE: internal/event/export/metric/info.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package metric

import (
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// Scalar represents the construction information for a scalar metric.
type Scalar struct {
	// Name is the unique name of this metric.
	Name string
	// Description can be used by observers to describe the metric to users.
	Description string
	// Keys is the set of labels that collectively describe rows of the metric.
	Keys []label.Key
}

// HistogramInt64 represents the construction information for an int64 histogram metric.
type HistogramInt64 struct {
	// Name is the unique name of this metric.
	Name string
	// Description can be used by observers to describe the metric to users.
	Description string
	// Keys is the set of labels that collectively describe rows of the metric.
	Keys []label.Key
	// Buckets holds the inclusive upper bound of each bucket in the histogram.
	Buckets []int64
}

// HistogramFloat64 represents the construction information for a float64 histogram metric.
type HistogramFloat64 struct {
	// Name is the unique name of this metric.
	Name string
	// Description can be used by observers to describe the metric to users.
	Description string
	// Keys is the set of labels that collectively describe rows of the metric.
	Keys []label.Key
	// Buckets holds the inclusive upper bound of each bucket in the histogram.
	Buckets []float64
}

// Count creates a new metric based on the Scalar information that counts
// the number of times the supplied int64 measure is set.
// Metrics of this type will use Int64Data.
func (info Scalar) Count(e *Config, key label.Key) {
	data := &Int64Data{Info: &info, key: nil}
	e.subscribe(key, data.count)
}

// SumInt64 creates a new metric based on the Scalar information that sums all
// the values recorded on the int64 measure.
// Metrics of this type will use Int64Data.
func (info Scalar) SumInt64(e *Config, key *keys.Int) {
	data := &Int64Data{Info: &info, key: key}
	e.subscribe(key, data.sum)
}

// LatestInt64 creates a new metric based on the Scalar information that tracks
// the most recent value recorded on the int64 measure.
// Metrics of this type will use Int64Data.
func (info Scalar) LatestInt64(e *Config, key *keys.Int) {
	data := &Int64Data{Info: &info, IsGauge: true, key: key}
	e.subscribe(key, data.latest)
}

// SumFloat64 creates a new metric based on the Scalar information that sums all
// the values recorded on the float64 measure.
// Metrics of this type will use Float64Data.
func (info Scalar) SumFloat64(e *Config, key *keys.Float) {
	data := &Float64Data{Info: &info, key: key}
	e.subscribe(key, data.sum)
}

// LatestFloat64 creates a new metric based on the Scalar information that tracks
// the most recent value recorded on the float64 measure.
// Metrics of this type will use Float64Data.
func (info Scalar) LatestFloat64(e *Config, key *keys.Float) {
	data := &Float64Data{Info: &info, IsGauge: true, key: key}
	e.subscribe(key, data.latest)
}

// Record creates a new metric based on the HistogramInt64 information that
// tracks the bucketized counts of values recorded on the int64 measure.
// Metrics of this type will use HistogramInt64Data.
func (info HistogramInt64) Record(e *Config, key *keys.Int) {
	data := &HistogramInt64Data{Info: &info, key: key}
	e.subscribe(key, data.record)
}

// Record creates a new metric based on the HistogramFloat64 information that
// tracks the bucketized counts of values recorded on the float64 measure.
// Metrics of this type will use HistogramFloat64Data.
func (info HistogramFloat64) Record(e *Config, key *keys.Float) {
	data := &HistogramFloat64Data{Info: &info, key: key}
	e.subscribe(key, data.record)
}


================================================
FILE: internal/event/export/otel/common.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"fmt"

	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// labelToAttribute converts a label to an OTLP attribute.
// It returns false if the label has no value.
func labelToAttribute(l label.Label) (otlpAttribute, bool) {
	key := l.Key()
	var v otlpAttributeValue

	switch key := key.(type) {
	case *keys.Int:
		v = otlpAttributeValue{IntValue: varOf(intAsString(key.From(l)))}
	case *keys.Uint:
		v = otlpAttributeValue{IntValue: varOf(intAsString(key.From(l)))}
	case *keys.Float:
		v = otlpAttributeValue{DoubleValue: varOf(key.From(l))}
	case *keys.String:
		v = otlpAttributeValue{StringValue: varOf(key.From(l))}
	case *keys.Error:
		if err := key.From(l); err != nil {
			v = otlpAttributeValue{StringValue: varOf(err.Error())}
		}
	case *keys.Value:
		v = otlpAttributeValue{StringValue: varOf(fmt.Sprint(key.From(l)))}
	default:
		if l.Valid() {
			v = otlpAttributeValue{StringValue: varOf(fmt.Sprint(l))}
		}
	}

	hasValue := v.StringValue != nil || v.IntValue != nil || v.DoubleValue != nil
	return otlpAttribute{Key: key.Name(), Value: v}, hasValue
}

// TODO(adonovan): use go1.26 new(expr)
func varOf[T any](x T) *T { return &x }


================================================
FILE: internal/event/export/otel/metrics.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/label"
)

// convertMetric converts internal metric.Data to an OTLP metric.
func convertMetric(data metric.Data) otlpMetric {
	switch data := data.(type) {
	case *metric.Int64Data:
		return convertInt64Data(data)
	case *metric.Float64Data:
		return convertFloat64Data(data)
	case *metric.HistogramInt64Data:
		return convertHistogramInt64Data(data)
	case *metric.HistogramFloat64Data:
		return convertHistogramFloat64Data(data)
	default:
		return otlpMetric{Name: data.Handle()}
	}
}

func convertInt64Data(d *metric.Int64Data) otlpMetric {
	m := otlpMetric{
		Name:        d.Info.Name,
		Description: d.Info.Description,
	}

	groups := d.Groups()
	dataPoints := make([]otlpNumberDataPoint, len(d.Rows))
	for i, value := range d.Rows {
		v := intAsString(value)
		dp := otlpNumberDataPoint{
			TimeUnixNano: intAsString(d.EndTime.UnixNano()),
			AsInt:        &v, // TODO: use go1.26 new(value)
			Attributes:   labelsToAttributes(groups[i]),
		}
		dataPoints[i] = dp
	}

	if d.IsGauge {
		m.Gauge = &otlpGauge{DataPoints: dataPoints}
	} else {
		m.Sum = &otlpSum{
			DataPoints:             dataPoints,
			AggregationTemporality: 2, // cumulative
			IsMonotonic:            true,
		}
	}

	return m
}

func convertFloat64Data(d *metric.Float64Data) otlpMetric {
	m := otlpMetric{
		Name:        d.Info.Name,
		Description: d.Info.Description,
	}

	groups := d.Groups()
	dataPoints := make([]otlpNumberDataPoint, len(d.Rows))
	for i, value := range d.Rows {
		v := value
		dp := otlpNumberDataPoint{
			TimeUnixNano: intAsString(d.EndTime.UnixNano()),
			AsDouble:     &v, // TODO: use go1.26 new(value)
			Attributes:   labelsToAttributes(groups[i]),
		}
		dataPoints[i] = dp
	}

	if d.IsGauge {
		m.Gauge = &otlpGauge{DataPoints: dataPoints}
	} else {
		m.Sum = &otlpSum{
			DataPoints:             dataPoints,
			AggregationTemporality: 2, // cumulative
			IsMonotonic:            true,
		}
	}

	return m
}

func convertHistogramInt64Data(d *metric.HistogramInt64Data) otlpMetric {
	dataPoints := make([]otlpHistogramDataPoint, len(d.Rows))

	// Convert bucket boundaries to float64
	bounds := make([]float64, len(d.Info.Buckets))
	for i, b := range d.Info.Buckets {
		bounds[i] = float64(b)
	}

	groups := d.Groups()
	for i, row := range d.Rows {
		// OTLP expects bucket counts, not cumulative counts
		// The internal format uses cumulative, so we need to convert
		bucketCounts := make([]intAsString, len(row.Values)+1)
		var prev int64
		for j, v := range row.Values {
			bucketCounts[j] = intAsString(v - prev)
			prev = v
		}
		// Last bucket is for values > last bound
		bucketCounts[len(row.Values)] = intAsString(row.Count - prev)

		sum := float64(row.Sum)
		min := float64(row.Min)
		max := float64(row.Max)
		dp := otlpHistogramDataPoint{
			TimeUnixNano:   intAsString(d.EndTime.UnixNano()),
			Count:          intAsString(row.Count),
			Sum:            &sum, // TODO: use go1.26 new(value)
			BucketCounts:   bucketCounts,
			ExplicitBounds: bounds,
			Min:            &min, // TODO: use go1.26 new(value)
			Max:            &max, // TODO: use go1.26 new(value)
			Attributes:     labelsToAttributes(groups[i]),
		}
		dataPoints[i] = dp
	}

	return otlpMetric{
		Name:        d.Info.Name,
		Description: d.Info.Description,
		Histogram: &otlpHistogram{
			DataPoints:             dataPoints,
			AggregationTemporality: 2, // cumulative
		},
	}
}

func convertHistogramFloat64Data(d *metric.HistogramFloat64Data) otlpMetric {
	dataPoints := make([]otlpHistogramDataPoint, len(d.Rows))

	groups := d.Groups()
	for i, row := range d.Rows {
		// Convert cumulative to bucket counts
		bucketCounts := make([]intAsString, len(row.Values)+1)
		var prev int64
		for j, v := range row.Values {
			bucketCounts[j] = intAsString(v - prev)
			prev = v
		}
		bucketCounts[len(row.Values)] = intAsString(row.Count - prev)

		sum := row.Sum
		min := row.Min
		max := row.Max
		dp := otlpHistogramDataPoint{
			TimeUnixNano:   intAsString(d.EndTime.UnixNano()),
			Count:          intAsString(row.Count),
			Sum:            &sum, // TODO: use go1.26 new(value)
			BucketCounts:   bucketCounts,
			ExplicitBounds: d.Info.Buckets,
			Min:            &min, // TODO: use go1.26 new(value)
			Max:            &max, // TODO: use go1.26 new(value)
			Attributes:     labelsToAttributes(groups[i]),
		}
		dataPoints[i] = dp
	}

	return otlpMetric{
		Name:        d.Info.Name,
		Description: d.Info.Description,
		Histogram: &otlpHistogram{
			DataPoints:             dataPoints,
			AggregationTemporality: 2, // cumulative
		},
	}
}

// labelsToAttributes converts a slice of labels to OTLP attributes.
func labelsToAttributes(labels []label.Label) []otlpAttribute {
	attrs := make([]otlpAttribute, 0, len(labels))
	for _, l := range labels {
		if attr, ok := labelToAttribute(l); ok {
			attrs = append(attrs, attr)
		}
	}
	return attrs
}

// exportMetrics sends metrics to the OTLP endpoint.
func (e *Exporter) exportMetrics(metrics []otlpMetric) error {
	req := otlpMetricsRequest{
		ResourceMetrics: []otlpResourceMetrics{{
			Resource: e.resource,
			ScopeMetrics: []otlpScopeMetrics{{
				Scope:   otlpScope{Name: "golang.org/x/tools"},
				Metrics: metrics,
			}},
		}},
	}
	return e.post("/v1/metrics", req)
}


================================================
FILE: internal/event/export/otel/metrics_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"context"
	"testing"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// captureMetricData creates a metric using the production event system and returns the resulting data.
func captureMetricData(name string, setup func(*metric.Config), record func(context.Context)) metric.Data {
	var captured metric.Data

	output := func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		if event.IsMetric(ev) {
			if entries := metric.Entries.Get(lm); entries != nil {
				for _, data := range entries.([]metric.Data) {
					if data.Handle() == name {
						captured = data
					}
				}
			}
		}
		return ctx
	}

	cfg := metric.Config{}
	setup(&cfg)

	event.SetExporter(cfg.Exporter(output))
	defer event.SetExporter(nil)

	record(context.Background())
	return captured
}

func TestConvertInt64Data_Counter(t *testing.T) {
	key := keys.NewInt("value", "")

	data := captureMetricData("request_count", func(cfg *metric.Config) {
		metric.Scalar{
			Name:        "request_count",
			Description: "Number of requests",
		}.SumInt64(cfg, key)
	}, func(ctx context.Context) {
		event.Metric(ctx, key.Of(42))
	}).(*metric.Int64Data)

	m := convertInt64Data(data)

	if m.Name != "request_count" {
		t.Errorf("expected name 'request_count', got %q", m.Name)
	}
	if m.Description != "Number of requests" {
		t.Errorf("expected description 'Number of requests', got %q", m.Description)
	}
	if m.Gauge != nil {
		t.Error("expected Gauge to be nil for counter")
	}
	if m.Sum == nil {
		t.Fatal("expected Sum to be non-nil for counter")
	}
	if len(m.Sum.DataPoints) != 1 {
		t.Fatalf("expected 1 data point, got %d", len(m.Sum.DataPoints))
	}
	if m.Sum.DataPoints[0].AsInt == nil || *m.Sum.DataPoints[0].AsInt != 42 {
		t.Errorf("expected value 42, got %v", m.Sum.DataPoints[0].AsInt)
	}
	if !m.Sum.IsMonotonic {
		t.Error("expected IsMonotonic to be true for counter")
	}
}

func TestConvertInt64Data_Gauge(t *testing.T) {
	key := keys.NewInt("value", "")

	data := captureMetricData("current_connections", func(cfg *metric.Config) {
		metric.Scalar{Name: "current_connections"}.LatestInt64(cfg, key)
	}, func(ctx context.Context) {
		event.Metric(ctx, key.Of(100))
	}).(*metric.Int64Data)

	m := convertInt64Data(data)

	if m.Sum != nil {
		t.Error("expected Sum to be nil for gauge")
	}
	if m.Gauge == nil {
		t.Fatal("expected Gauge to be non-nil")
	}
	if len(m.Gauge.DataPoints) != 1 {
		t.Fatalf("expected 1 data point, got %d", len(m.Gauge.DataPoints))
	}
	if m.Gauge.DataPoints[0].AsInt == nil || *m.Gauge.DataPoints[0].AsInt != 100 {
		t.Errorf("expected value 100, got %v", m.Gauge.DataPoints[0].AsInt)
	}
}

func TestConvertFloat64Data(t *testing.T) {
	key := keys.NewFloat("value", "")

	data := captureMetricData("cpu_usage", func(cfg *metric.Config) {
		metric.Scalar{Name: "cpu_usage"}.LatestFloat64(cfg, key)
	}, func(ctx context.Context) {
		event.Metric(ctx, key.Of(0.75))
	}).(*metric.Float64Data)

	m := convertFloat64Data(data)

	if m.Gauge == nil {
		t.Fatal("expected Gauge to be non-nil")
	}
	if len(m.Gauge.DataPoints) != 1 {
		t.Fatalf("expected 1 data point, got %d", len(m.Gauge.DataPoints))
	}
	if m.Gauge.DataPoints[0].AsDouble == nil || *m.Gauge.DataPoints[0].AsDouble != 0.75 {
		t.Errorf("expected value 0.75, got %v", m.Gauge.DataPoints[0].AsDouble)
	}
}

func TestConvertHistogramInt64Data(t *testing.T) {
	key := keys.NewInt("value", "")
	buckets := []int64{10, 50, 100, 500}

	// Record multiple values across different buckets:
	// Bucket boundaries: <=10, <=50, <=100, <=500, >500
	// Values: 5, 8 (<=10), 20, 30, 40 (<=50), 75 (<=100), 200, 300 (<=500), 1000 (>500)
	values := []int{5, 8, 20, 30, 40, 75, 200, 300, 1000}

	data := captureMetricData("response_time", func(cfg *metric.Config) {
		metric.HistogramInt64{
			Name:        "response_time",
			Description: "Response time in ms",
			Buckets:     buckets,
		}.Record(cfg, key)
	}, func(ctx context.Context) {
		for _, v := range values {
			event.Metric(ctx, key.Of(v))
		}
	}).(*metric.HistogramInt64Data)

	m := convertHistogramInt64Data(data)

	if m.Histogram == nil {
		t.Fatal("expected Histogram to be non-nil")
	}
	dp := m.Histogram.DataPoints[0]

	// Verify count
	if dp.Count != 9 {
		t.Errorf("expected count 9, got %d", dp.Count)
	}

	// Verify sum: 5+8+20+30+40+75+200+300+1000 = 1678
	if dp.Sum == nil || *dp.Sum != 1678 {
		t.Errorf("expected sum 1678, got %v", dp.Sum)
	}

	// Verify min/max
	if dp.Min == nil || *dp.Min != 5 {
		t.Errorf("expected min 5, got %v", dp.Min)
	}
	if dp.Max == nil || *dp.Max != 1000 {
		t.Errorf("expected max 1000, got %v", dp.Max)
	}

	// Verify bucket counts (non-cumulative):
	// <=10: 2 (5, 8)
	// <=50: 3 (20, 30, 40)
	// <=100: 1 (75)
	// <=500: 2 (200, 300)
	// >500: 1 (1000)
	expectedBuckets := []intAsString{2, 3, 1, 2, 1}
	if len(dp.BucketCounts) != len(expectedBuckets) {
		t.Fatalf("expected %d buckets, got %d", len(expectedBuckets), len(dp.BucketCounts))
	}
	for i, expected := range expectedBuckets {
		if dp.BucketCounts[i] != expected {
			t.Errorf("bucket[%d]: expected %d, got %d", i, expected, dp.BucketCounts[i])
		}
	}

	// Verify explicit bounds match configured buckets
	expectedBounds := []float64{10, 50, 100, 500}
	if len(dp.ExplicitBounds) != len(expectedBounds) {
		t.Fatalf("expected %d bounds, got %d", len(expectedBounds), len(dp.ExplicitBounds))
	}
	for i, expected := range expectedBounds {
		if dp.ExplicitBounds[i] != expected {
			t.Errorf("bound[%d]: expected %v, got %v", i, expected, dp.ExplicitBounds[i])
		}
	}
}

func TestConvertInt64Data_WithAttributes(t *testing.T) {
	valueKey := keys.NewInt("value", "")
	methodKey := keys.NewString("method", "")

	data := captureMetricData("requests_by_method", func(cfg *metric.Config) {
		metric.Scalar{
			Name: "requests_by_method",
			Keys: []label.Key{methodKey}, // Group by method
		}.SumInt64(cfg, valueKey)
	}, func(ctx context.Context) {
		event.Metric(ctx, valueKey.Of(10), methodKey.Of("GET"))
		event.Metric(ctx, valueKey.Of(5), methodKey.Of("POST"))
	}).(*metric.Int64Data)

	m := convertInt64Data(data)

	// Should have 2 data points (one per method)
	if len(m.Sum.DataPoints) != 2 {
		t.Fatalf("expected 2 data points, got %d", len(m.Sum.DataPoints))
	}

	// Verify attributes contain the method labels
	for _, dp := range m.Sum.DataPoints {
		if len(dp.Attributes) != 1 {
			t.Errorf("expected 1 attribute, got %d", len(dp.Attributes))
		}
		if dp.Attributes[0].Key != "method" {
			t.Errorf("expected attribute key 'method', got %q", dp.Attributes[0].Key)
		}
		// Value should be "GET" or "POST"
		sv := dp.Attributes[0].Value.StringValue
		if sv == nil || (*sv != "GET" && *sv != "POST") {
			t.Errorf("unexpected method value: %v", sv)
		}
	}
}


================================================
FILE: internal/event/export/otel/options.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"time"
)

// Default configuration values.
const (
	DefaultEndpoint    = "http://localhost:4318"
	DefaultServiceName = "unknown_service"
	DefaultTimeout     = 10 * time.Second
	DefaultFlushPeriod = 2 * time.Second
)

// Option configures an OTelExporter.
type Option func(*Exporter)

// WithEndpoint sets the OTLP HTTP endpoint.
func WithEndpoint(endpoint string) Option {
	return func(e *Exporter) {
		e.endpoint = endpoint
	}
}

// WithServiceName sets the service name for exported spans.
func WithServiceName(name string) Option {
	return func(e *Exporter) {
		e.serviceName = name
	}
}

// WithTimeout sets the HTTP client timeout.
func WithTimeout(timeout time.Duration) Option {
	return func(e *Exporter) {
		e.client.Timeout = timeout
	}
}

// WithFlushPeriod sets the interval for automatic background flushing.
func WithFlushPeriod(period time.Duration) Option {
	return func(e *Exporter) {
		e.flushPeriod = period
	}
}

// WithServiceVersion sets the service version for exported telemetry.
func WithServiceVersion(version string) Option {
	return func(e *Exporter) {
		e.serviceVersion = version
	}
}


================================================
FILE: internal/event/export/otel/otel.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package otel exports spans and metrics to an OpenTelemetry
// collector using the OTLP HTTP/JSON protocol.
//
// Use [NewExporter] to create an exporter, then chain its
// [Exporter.ProcessEvent] method with other exporters:
//
//	otelExporter := otel.NewExporter(ctx,
//		otel.WithEndpoint("http://localhost:4318"),
//		otel.WithServiceName("myservice"),
//	)
//	event.SetExporter(otelExporter.ProcessEvent)
//
// The exporter batches telemetry and flushes periodically in a
// background goroutine. Call [Exporter.Flush] to force an
// immediate export.
package otel

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"os"
	"runtime"
	"strconv"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/label"
)

// Exporter exports spans and metrics to an OTLP HTTP endpoint.
type Exporter struct {
	mu             sync.Mutex
	endpoint       string
	serviceName    string
	serviceVersion string
	resource       otlpResource
	client         *http.Client
	flushPeriod    time.Duration
	spans          []*export.Span
	metrics        map[string]metric.Data
}

// NewExporter creates an exporter that sends spans to an OTLP endpoint.
// Spans are collected and exported periodically in a background goroutine.
// When the context is done, remaining spans are flushed.
func NewExporter(ctx context.Context, opts ...Option) *Exporter {
	e := &Exporter{
		endpoint:    DefaultEndpoint,
		serviceName: DefaultServiceName,
		client:      &http.Client{Timeout: DefaultTimeout},
		flushPeriod: DefaultFlushPeriod,
	}

	for _, opt := range opts {
		opt(e)
	}

	e.resource = e.buildResource()

	go func() {
		ticker := time.NewTicker(e.flushPeriod)
		defer ticker.Stop()
		for {
			select {
			case <-ctx.Done():
				e.Flush() // final flush before exiting
				return
			case <-ticker.C:
				e.Flush()
			}
		}
	}()

	return e
}

// ProcessEvent handles events and collects completed spans and metrics.
func (e *Exporter) ProcessEvent(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	e.mu.Lock()
	defer e.mu.Unlock()

	if event.IsEnd(ev) {
		if span := export.GetSpan(ctx); span != nil {
			e.spans = append(e.spans, span)
		}
	}

	if event.IsMetric(ev) {
		if e.metrics == nil {
			e.metrics = make(map[string]metric.Data)
		}
		if entries := metric.Entries.Get(lm); entries != nil {
			for _, data := range entries.([]metric.Data) {
				e.metrics[data.Handle()] = data
			}
		}
	}

	return ctx
}

// Flush exports all collected spans and metrics to the OTLP endpoint.
func (e *Exporter) Flush() {
	e.mu.Lock()
	spans := e.spans
	e.spans = nil
	metrics := e.metrics
	e.metrics = nil
	e.mu.Unlock()

	// Export spans
	if len(spans) > 0 {
		otlpSpans := make([]otlpSpan, 0, len(spans))
		for _, span := range spans {
			otlpSpans = append(otlpSpans, convertSpan(span))
		}
		if err := e.exportTraces(otlpSpans); err != nil {
			log.Printf("post spans: %v", err)
			return
		}
	}

	// Export metrics
	if len(metrics) > 0 {
		otlpMetrics := make([]otlpMetric, 0, len(metrics))
		for _, data := range metrics {
			otlpMetrics = append(otlpMetrics, convertMetric(data))
		}
		if err := e.exportMetrics(otlpMetrics); err != nil {
			log.Printf("post metrics: %v", err)
		}
	}
}

// post sends a JSON payload to the OTLP endpoint.
func (e *Exporter) post(path string, payload any) error {
	data, err := json.Marshal(payload)
	if err != nil {
		return err
	}

	// The background context is appropriate here since post is called only
	// from Flush, which is called only by the Exporter's background goroutine.
	// Notably it may be called after cancellation of the client's context.
	req, err := http.NewRequestWithContext(context.Background(), "POST", e.endpoint+path, bytes.NewReader(data))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")

	resp, err := e.client.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

	if resp.StatusCode >= 400 {
		return fmt.Errorf("OTLP export to %s failed with status %d", path, resp.StatusCode)
	}
	return nil
}

func (e *Exporter) buildResource() otlpResource {
	attrs := []otlpAttribute{
		{Key: "service.name", Value: otlpAttributeValue{StringValue: &e.serviceName}},
		{Key: "process.runtime.version", Value: otlpAttributeValue{StringValue: varOf(runtime.Version())}},
		{Key: "process.pid", Value: otlpAttributeValue{StringValue: varOf(strconv.Itoa(os.Getpid()))}},
		{Key: "host.arch", Value: otlpAttributeValue{StringValue: varOf(runtime.GOARCH)}},
		{Key: "os.type", Value: otlpAttributeValue{StringValue: varOf(runtime.GOOS)}},
	}

	if hostname, err := os.Hostname(); err == nil {
		attrs = append(attrs, otlpAttribute{
			Key:   "host.name",
			Value: otlpAttributeValue{StringValue: &hostname},
		})
	}

	if e.serviceVersion != "" {
		attrs = append(attrs, otlpAttribute{
			Key:   "service.version",
			Value: otlpAttributeValue{StringValue: &e.serviceVersion},
		})
	}

	return otlpResource{Attributes: attrs}
}


================================================
FILE: internal/event/export/otel/otel_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"errors"
	"testing"

	"golang.org/x/tools/internal/event/keys"
)

func TestLabelToAttribute_String(t *testing.T) {
	key := keys.NewString("mykey", "")
	l := key.Of("myvalue")

	attr, ok := labelToAttribute(l)
	if !ok {
		t.Fatal("expected ok=true")
	}
	if attr.Key != "mykey" {
		t.Errorf("expected key 'mykey', got %q", attr.Key)
	}
	if attr.Value.StringValue == nil || *attr.Value.StringValue != "myvalue" {
		t.Errorf("expected stringValue 'myvalue', got %v", attr.Value.StringValue)
	}
}

func TestLabelToAttribute_Int(t *testing.T) {
	key := keys.NewInt("count", "")
	l := key.Of(42)

	attr, ok := labelToAttribute(l)
	if !ok {
		t.Fatal("expected ok=true")
	}
	if attr.Key != "count" {
		t.Errorf("expected key 'count', got %q", attr.Key)
	}
	if attr.Value.IntValue == nil || *attr.Value.IntValue != 42 {
		t.Errorf("expected intValue 42, got %v", attr.Value.IntValue)
	}
}

func TestLabelToAttribute_Float(t *testing.T) {
	key := keys.NewFloat("ratio", "")
	l := key.Of(3.14)

	attr, ok := labelToAttribute(l)
	if !ok {
		t.Fatal("expected ok=true")
	}
	if attr.Key != "ratio" {
		t.Errorf("expected key 'ratio', got %q", attr.Key)
	}
	if attr.Value.DoubleValue == nil || *attr.Value.DoubleValue != 3.14 {
		t.Errorf("expected doubleValue 3.14, got %v", attr.Value.DoubleValue)
	}
}

func TestLabelToAttribute_Error(t *testing.T) {
	key := keys.NewError("err", "")
	l := key.Of(errors.New("something failed"))

	attr, ok := labelToAttribute(l)
	if !ok {
		t.Fatal("expected ok=true")
	}
	if attr.Key != "err" {
		t.Errorf("expected key 'err', got %q", attr.Key)
	}
	if attr.Value.StringValue == nil || *attr.Value.StringValue != "something failed" {
		t.Errorf("expected stringValue 'something failed', got %v", attr.Value.StringValue)
	}
}

func TestLabelToAttribute_NilError(t *testing.T) {
	key := keys.NewError("err", "")
	l := key.Of(nil)

	_, ok := labelToAttribute(l)
	if ok {
		t.Error("expected ok=false for nil error")
	}
}


================================================
FILE: internal/event/export/otel/otlp.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"fmt"
	"strconv"
)

// OTLP JSON types for telemetry export.
//
// Specification
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/docs/specification.md

// intAsString is an int64 that marshals to/from a JSON string.
//
// int64 values are encoded as strings because JSON numbers are IEEE 754
// double-precision floats, which can only represent integers exactly up to
// 2^53. Timestamps in nanoseconds and large counts would lose precision.
// See: https://github.com/open-telemetry/opentelemetry-proto/issues/268
// And: https://protobuf.dev/programming-guides/json/
type intAsString int64

func (i intAsString) MarshalJSON() ([]byte, error) {
	return fmt.Appendf(nil, `"%d"`, i), nil
}

func (i *intAsString) UnmarshalJSON(data []byte) error {
	// Strip quotes if present. Per the spec, both JSON strings ("123")
	// and JSON numbers (123) must be accepted for decoding int64 values.
	if len(data) >= 2 && data[0] == '"' && data[len(data)-1] == '"' {
		data = data[1 : len(data)-1]
	}
	v, err := strconv.ParseInt(string(data), 10, 64)
	if err != nil {
		return err
	}
	*i = intAsString(v)
	return nil
}

// Common oltp types

// otlpResource corresponds to Resource.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/resource/v1/resource.proto#L28
type otlpResource struct {
	Attributes []otlpAttribute `json:"attributes"`
}

// otlpScope corresponds to InstrumentationScope.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/common/v1/common.proto#L76
type otlpScope struct {
	Name    string `json:"name,omitempty"`
	Version string `json:"version,omitempty"`
}

// otlpAttribute corresponds to KeyValue.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/common/v1/common.proto#L66
type otlpAttribute struct {
	Key   string             `json:"key"`
	Value otlpAttributeValue `json:"value"`
}

// otlpAttributeValue corresponds to AnyValue.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/common/v1/common.proto#L28
type otlpAttributeValue struct {
	StringValue *string      `json:"stringValue,omitempty"`
	IntValue    *intAsString `json:"intValue,omitempty"`
	DoubleValue *float64     `json:"doubleValue,omitempty"`
	BoolValue   *bool        `json:"boolValue,omitempty"`
}

// Trace types

// otlpTraceExportRequest is the payload for ExportTraceServiceRequest.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/collector/trace/v1/trace_service.proto#L34
type otlpTraceExportRequest struct {
	ResourceSpans []otlpResourceSpans `json:"resourceSpans"`
}

// otlpResourceSpans corresponds to ResourceSpans.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/trace/v1/trace.proto#L48
type otlpResourceSpans struct {
	Resource   otlpResource     `json:"resource"`
	ScopeSpans []otlpScopeSpans `json:"scopeSpans"`
}

// otlpScopeSpans corresponds to ScopeSpans.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/trace/v1/trace.proto#L68
type otlpScopeSpans struct {
	Scope otlpScope  `json:"scope"`
	Spans []otlpSpan `json:"spans"`
}

// otlpSpan corresponds to Span.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/trace/v1/trace.proto#L89
type otlpSpan struct {
	TraceID           string          `json:"traceId"`
	SpanID            string          `json:"spanId"`
	ParentSpanID      string          `json:"parentSpanId,omitempty"`
	Name              string          `json:"name"`
	Kind              int             `json:"kind"`
	StartTimeUnixNano intAsString     `json:"startTimeUnixNano"`
	EndTimeUnixNano   intAsString     `json:"endTimeUnixNano"`
	Attributes        []otlpAttribute `json:"attributes,omitempty"`
	Status            otlpSpanStatus  `json:"status"`
}

// otlpSpanStatus corresponds to Status.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/trace/v1/trace.proto#L308
type otlpSpanStatus struct {
	Code    int    `json:"code"`
	Message string `json:"message,omitempty"`
}

// Metrics types

// otlpMetricsRequest is the payload for ExportMetricsServiceRequest.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/collector/metrics/v1/metrics_service.proto#L34
type otlpMetricsRequest struct {
	ResourceMetrics []otlpResourceMetrics `json:"resourceMetrics"`
}

// otlpResourceMetrics corresponds to ResourceMetrics.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L66
type otlpResourceMetrics struct {
	Resource     otlpResource       `json:"resource"`
	ScopeMetrics []otlpScopeMetrics `json:"scopeMetrics"`
}

// otlpScopeMetrics corresponds to ScopeMetrics.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L86
type otlpScopeMetrics struct {
	Scope   otlpScope    `json:"scope"`
	Metrics []otlpMetric `json:"metrics"`
}

// otlpMetric corresponds to Metric.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L188
type otlpMetric struct {
	Name        string         `json:"name"`
	Description string         `json:"description,omitempty"`
	Unit        string         `json:"unit,omitempty"`
	Gauge       *otlpGauge     `json:"gauge,omitempty"`
	Sum         *otlpSum       `json:"sum,omitempty"`
	Histogram   *otlpHistogram `json:"histogram,omitempty"`
}

// otlpGauge corresponds to Gauge.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L232
type otlpGauge struct {
	DataPoints []otlpNumberDataPoint `json:"dataPoints"`
}

// otlpSum corresponds to Sum.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L240
type otlpSum struct {
	DataPoints             []otlpNumberDataPoint `json:"dataPoints"`
	AggregationTemporality int                   `json:"aggregationTemporality"` // 1=delta, 2=cumulative
	IsMonotonic            bool                  `json:"isMonotonic"`
}

// otlpHistogram corresponds to Histogram.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L255
type otlpHistogram struct {
	DataPoints             []otlpHistogramDataPoint `json:"dataPoints"`
	AggregationTemporality int                      `json:"aggregationTemporality"`
}

// otlpNumberDataPoint corresponds to NumberDataPoint.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L385
type otlpNumberDataPoint struct {
	Attributes   []otlpAttribute `json:"attributes,omitempty"`
	TimeUnixNano intAsString     `json:"timeUnixNano"`
	AsInt        *intAsString    `json:"asInt,omitempty"`
	AsDouble     *float64        `json:"asDouble,omitempty"`
}

// otlpHistogramDataPoint corresponds to HistogramDataPoint.
// https://github.com/open-telemetry/opentelemetry-proto/blob/v1.9.0/opentelemetry/proto/metrics/v1/metrics.proto#L434
type otlpHistogramDataPoint struct {
	Attributes     []otlpAttribute `json:"attributes,omitempty"`
	TimeUnixNano   intAsString     `json:"timeUnixNano"`
	Count          intAsString     `json:"count"`
	Sum            *float64        `json:"sum,omitempty"`
	BucketCounts   []intAsString   `json:"bucketCounts"`
	ExplicitBounds []float64       `json:"explicitBounds"`
	Min            *float64        `json:"min,omitempty"`
	Max            *float64        `json:"max,omitempty"`
}


================================================
FILE: internal/event/export/otel/traces.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"slices"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/keys"
)

// exportTraces sends traces to the OTLP endpoint.
func (e *Exporter) exportTraces(spans []otlpSpan) error {
	req := otlpTraceExportRequest{
		ResourceSpans: []otlpResourceSpans{{
			Resource: e.resource,
			ScopeSpans: []otlpScopeSpans{{
				Scope: otlpScope{Name: "golang.org/x/tools"},
				Spans: spans,
			}},
		}},
	}
	return e.post("/v1/traces", req)
}

// convertSpan converts an internal Span to an OTLP span.
func convertSpan(span *export.Span) otlpSpan {
	s := otlpSpan{
		TraceID: span.ID.TraceID.String(),
		SpanID:  span.ID.SpanID.String(),
		Name:    span.Name,
		Kind:    1,                       // SPAN_KIND_INTERNAL
		Status:  otlpSpanStatus{Code: 0}, // STATUS_CODE_UNSET
	}

	if span.ParentID.IsValid() {
		s.ParentSpanID = span.ParentID.String()
	}

	// Get timestamps from start event
	startEvent := span.Start()
	if !startEvent.At().IsZero() {
		s.StartTimeUnixNano = intAsString(startEvent.At().UnixNano())
	}

	// Get end timestamp from finish event
	finishEvent := span.Finish()
	if !finishEvent.At().IsZero() {
		s.EndTimeUnixNano = intAsString(finishEvent.At().UnixNano())
	}

	// Check for errors in span events to set status
	if slices.ContainsFunc(span.Events(), event.IsError) {
		s.Status.Code = 2 // STATUS_CODE_ERROR
	}

	// Extract attributes from span events
	s.Attributes = extractAttributes(span)

	return s
}

// extractAttributes extracts labels from span events as OTLP attributes.
func extractAttributes(span *export.Span) []otlpAttribute {
	var attrs []otlpAttribute

	// Extract from start event
	startEvent := span.Start()
	attrs = appendEventAttributes(attrs, startEvent)

	// Extract from logged events
	for _, ev := range span.Events() {
		attrs = appendEventAttributes(attrs, ev)
	}

	return attrs
}

// appendEventAttributes appends labels from an event as attributes.
func appendEventAttributes(attrs []otlpAttribute, ev core.Event) []otlpAttribute {
	for l := range ev.Labels() {
		key := l.Key()
		// Skip internal event type markers
		if key == keys.Start || key == keys.End || key == keys.Label ||
			key == keys.Detach || key == keys.Metric {
			continue
		}

		if attr, ok := labelToAttribute(l); ok {
			attrs = append(attrs, attr)
		}
	}
	return attrs
}


================================================
FILE: internal/event/export/otel/traces_test.go
================================================
// Copyright 2026 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package otel

import (
	"context"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"sync"
	"testing"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export"
	"golang.org/x/tools/internal/event/label"
)

func TestConvertSpan(t *testing.T) {
	span := &export.Span{
		Name: "test-operation",
		ID: export.SpanContext{
			TraceID: export.TraceID{1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16},
			SpanID:  export.SpanID{1, 2, 3, 4, 5, 6, 7, 8},
		},
		ParentID: export.SpanID{8, 7, 6, 5, 4, 3, 2, 1},
	}

	result := convertSpan(span)

	if result.Name != "test-operation" {
		t.Errorf("expected name 'test-operation', got %q", result.Name)
	}
	if result.TraceID != "0102030405060708090a0b0c0d0e0f10" {
		t.Errorf("unexpected traceId: %s", result.TraceID)
	}
	if result.SpanID != "0102030405060708" {
		t.Errorf("unexpected spanId: %s", result.SpanID)
	}
	if result.ParentSpanID != "0807060504030201" {
		t.Errorf("unexpected parentSpanId: %s", result.ParentSpanID)
	}
	if result.Kind != 1 {
		t.Errorf("expected kind 1, got %d", result.Kind)
	}
	if result.Status.Code != 0 {
		t.Errorf("expected status code 0, got %d", result.Status.Code)
	}
}

// TestE2E_SpanExport is a minimal end-to-end test verifying the full pipeline.
func TestE2E_SpanExport(t *testing.T) {
	var received []byte
	var mu sync.Mutex

	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		mu.Lock()
		received, _ = io.ReadAll(r.Body)
		mu.Unlock()
		w.WriteHeader(http.StatusOK)
	}))
	defer server.Close()

	baseExporter := func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		return ctx
	}
	spansExporter := export.Spans(baseExporter)
	otelExporter := NewExporter(context.Background(), WithEndpoint(server.URL))

	chainedExporter := func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		ctx = spansExporter(ctx, ev, lm)
		return otelExporter.ProcessEvent(ctx, ev, lm)
	}

	event.SetExporter(chainedExporter)

	ctx := context.Background()
	ctx, end := event.Start(ctx, "e2e-span")
	end()

	otelExporter.Flush()

	mu.Lock()
	data := received
	mu.Unlock()

	if len(data) == 0 {
		t.Fatal("no data received")
	}

	// Just verify it's valid JSON with a span
	var req otlpTraceExportRequest
	if err := json.Unmarshal(data, &req); err != nil {
		t.Fatalf("invalid JSON: %v", err)
	}
	if len(req.ResourceSpans) == 0 ||
		len(req.ResourceSpans[0].ScopeSpans) == 0 ||
		len(req.ResourceSpans[0].ScopeSpans[0].Spans) == 0 {
		t.Fatal("expected at least one span")
	}
}


================================================
FILE: internal/event/export/printer.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export

import (
	"io"

	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

type Printer struct {
	buffer [128]byte
}

// WriteEvent writes the formatted event to w. It is not concurrency-safe.
func (p *Printer) WriteEvent(w io.Writer, ev core.Event, lm label.Map) {
	// TODO(adonovan): any function that accepts an arbitrary
	// io.Writer should really deal with errors. Use bytes.Buffer?
	buf := p.buffer[:0]
	if !ev.At().IsZero() {
		w.Write(ev.At().AppendFormat(buf, "2006/01/02 15:04:05 ")) // ignore error
	}
	msg := keys.Msg.Get(lm)
	io.WriteString(w, msg)
	if err := keys.Err.Get(lm); err != nil {
		if msg != "" {
			io.WriteString(w, ": ")
		}
		io.WriteString(w, err.Error())
	}
	for l := range ev.Labels() {
		if l.Key() == keys.Msg || l.Key() == keys.Err {
			continue
		}
		io.WriteString(w, "\n\t")
		io.WriteString(w, l.Key().Name())
		io.WriteString(w, "=")
		w.Write(l.Key().Append(buf, l)) // ignore error
	}
	io.WriteString(w, "\n")
}


================================================
FILE: internal/event/export/prometheus/prometheus.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package prometheus

import (
	"bytes"
	"context"
	"fmt"
	"net/http"
	"sort"
	"sync"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/export/metric"
	"golang.org/x/tools/internal/event/label"
)

func New() *Exporter {
	return &Exporter{}
}

type Exporter struct {
	mu      sync.Mutex
	metrics []metric.Data
}

func (e *Exporter) ProcessEvent(ctx context.Context, ev core.Event, lm label.Map) context.Context {
	if !event.IsMetric(ev) {
		return ctx
	}
	e.mu.Lock()
	defer e.mu.Unlock()
	metrics := metric.Entries.Get(lm).([]metric.Data)
	for _, data := range metrics {
		name := data.Handle()
		// We keep the metrics in name sorted order so the page is stable and easy
		// to read. We do this with an insertion sort rather than sorting the list
		// each time
		index := sort.Search(len(e.metrics), func(i int) bool {
			return e.metrics[i].Handle() >= name
		})
		if index >= len(e.metrics) || e.metrics[index].Handle() != name {
			// we have a new metric, so we need to make a space for it
			old := e.metrics
			e.metrics = make([]metric.Data, len(old)+1)
			copy(e.metrics, old[:index])
			copy(e.metrics[index+1:], old[index:])
		}
		e.metrics[index] = data
	}
	return ctx
}

func (e *Exporter) header(w http.ResponseWriter, name, description string, isGauge, isHistogram bool) {
	kind := "counter"
	if isGauge {
		kind = "gauge"
	}
	if isHistogram {
		kind = "histogram"
	}
	fmt.Fprintf(w, "# HELP %s %s\n", name, description)
	fmt.Fprintf(w, "# TYPE %s %s\n", name, kind)
}

func (e *Exporter) row(w http.ResponseWriter, name string, group []label.Label, extra string, value any) {
	fmt.Fprint(w, name)
	buf := &bytes.Buffer{}
	fmt.Fprint(buf, group)
	if extra != "" {
		if buf.Len() > 0 {
			fmt.Fprint(buf, ",")
		}
		fmt.Fprint(buf, extra)
	}
	if buf.Len() > 0 {
		fmt.Fprint(w, "{")
		buf.WriteTo(w)
		fmt.Fprint(w, "}")
	}
	fmt.Fprintf(w, " %v\n", value)
}

func (e *Exporter) Serve(w http.ResponseWriter, r *http.Request) {
	e.mu.Lock()
	defer e.mu.Unlock()
	for _, data := range e.metrics {
		switch data := data.(type) {
		case *metric.Int64Data:
			e.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
			for i, group := range data.Groups() {
				e.row(w, data.Info.Name, group, "", data.Rows[i])
			}

		case *metric.Float64Data:
			e.header(w, data.Info.Name, data.Info.Description, data.IsGauge, false)
			for i, group := range data.Groups() {
				e.row(w, data.Info.Name, group, "", data.Rows[i])
			}

		case *metric.HistogramInt64Data:
			e.header(w, data.Info.Name, data.Info.Description, false, true)
			for i, group := range data.Groups() {
				row := data.Rows[i]
				for j, b := range data.Info.Buckets {
					e.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
				}
				e.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
				e.row(w, data.Info.Name+"_count", group, "", row.Count)
				e.row(w, data.Info.Name+"_sum", group, "", row.Sum)
			}

		case *metric.HistogramFloat64Data:
			e.header(w, data.Info.Name, data.Info.Description, false, true)
			for i, group := range data.Groups() {
				row := data.Rows[i]
				for j, b := range data.Info.Buckets {
					e.row(w, data.Info.Name+"_bucket", group, fmt.Sprintf(`le="%v"`, b), row.Values[j])
				}
				e.row(w, data.Info.Name+"_bucket", group, `le="+Inf"`, row.Count)
				e.row(w, data.Info.Name+"_count", group, "", row.Count)
				e.row(w, data.Info.Name+"_sum", group, "", row.Sum)
			}
		}
	}
}


================================================
FILE: internal/event/export/trace.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package export

import (
	"context"
	"fmt"
	"sync"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/core"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

type SpanContext struct {
	TraceID TraceID
	SpanID  SpanID
}

type Span struct {
	Name     string
	ID       SpanContext
	ParentID SpanID
	mu       sync.Mutex
	start    core.Event
	finish   core.Event
	events   []core.Event
}

type contextKeyType int

const (
	spanContextKey = contextKeyType(iota)
	labelContextKey
)

func GetSpan(ctx context.Context) *Span {
	v := ctx.Value(spanContextKey)
	if v == nil {
		return nil
	}
	return v.(*Span)
}

// Spans creates an exporter that maintains hierarchical span structure in the
// context.
// It creates new spans on start events, adds events to the current span on
// log or label, and closes the span on end events.
// The span structure can then be used by other exporters.
func Spans(output event.Exporter) event.Exporter {
	return func(ctx context.Context, ev core.Event, lm label.Map) context.Context {
		switch {
		case event.IsLog(ev), event.IsLabel(ev):
			if span := GetSpan(ctx); span != nil {
				span.mu.Lock()
				span.events = append(span.events, ev)
				span.mu.Unlock()
			}
		case event.IsStart(ev):
			span := &Span{
				Name:  keys.Start.Get(lm),
				start: ev,
			}
			if parent := GetSpan(ctx); parent != nil {
				span.ID.TraceID = parent.ID.TraceID
				span.ParentID = parent.ID.SpanID
			} else {
				span.ID.TraceID = newTraceID()
			}
			span.ID.SpanID = newSpanID()
			ctx = context.WithValue(ctx, spanContextKey, span)
		case event.IsEnd(ev):
			if span := GetSpan(ctx); span != nil {
				span.mu.Lock()
				span.finish = ev
				span.mu.Unlock()
			}
		case event.IsDetach(ev):
			ctx = context.WithValue(ctx, spanContextKey, nil)
		}
		return output(ctx, ev, lm)
	}
}

func (s *SpanContext) Format(f fmt.State, r rune) {
	fmt.Fprintf(f, "%v:%v", s.TraceID, s.SpanID)
}

func (s *Span) Start() core.Event {
	// start never changes after construction, so we don't need to hold the mutex
	return s.start
}

func (s *Span) Finish() core.Event {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.finish
}

func (s *Span) Events() []core.Event {
	s.mu.Lock()
	defer s.mu.Unlock()
	return s.events
}

func (s *Span) Format(f fmt.State, r rune) {
	s.mu.Lock()
	defer s.mu.Unlock()
	fmt.Fprintf(f, "%v %v", s.Name, s.ID)
	if s.ParentID.IsValid() {
		fmt.Fprintf(f, "[%v]", s.ParentID)
	}
	fmt.Fprintf(f, " %v->%v", s.start, s.finish)
}


================================================
FILE: internal/event/keys/keys.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package keys

import (
	"fmt"
	"math"
	"strconv"

	"golang.org/x/tools/internal/event/label"
)

// Value is a [label.Key] for untyped values.
type Value struct {
	name        string
	description string
}

// New creates a new Key for untyped values.
func New(name, description string) *Value {
	return &Value{name: name, description: description}
}

func (k *Value) Name() string        { return k.name }
func (k *Value) Description() string { return k.description }

func (k *Value) Append(buf []byte, l label.Label) []byte {
	return fmt.Append(buf, k.From(l))
}

// Get returns the label for the key of a label.Map.
func (k *Value) Get(lm label.Map) any {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return nil
}

// From returns the value of a Label.
func (k *Value) From(t label.Label) any { return t.UnpackValue() }

// Of creates a new Label with this key and the supplied value.
func (k *Value) Of(value any) label.Label { return label.OfValue(k, value) }

// Tag represents a key for tagging labels that have no value.
// These are used when the existence of the label is the entire information it
// carries, such as marking events to be of a specific kind, or from a specific
// package.
type Tag struct {
	name        string
	description string
}

// NewTag creates a new [label.Key] for tagging labels.
func NewTag(name, description string) *Tag {
	return &Tag{name: name, description: description}
}

func (k *Tag) Name() string        { return k.name }
func (k *Tag) Description() string { return k.description }

func (k *Tag) Append(buf []byte, l label.Label) []byte { return buf }

// New creates a new Label with this key.
func (k *Tag) New() label.Label { return label.OfValue(k, nil) }

// Int is a [label.Key] for signed integers.
type Int struct {
	name        string
	description string
}

// NewInt returns a new [label.Key] for int64 values.
func NewInt(name, description string) *Int {
	return &Int{name: name, description: description}
}

func (k *Int) Name() string        { return k.name }
func (k *Int) Description() string { return k.description }

func (k *Int) Append(buf []byte, l label.Label) []byte {
	return strconv.AppendInt(buf, k.From(l), 10)
}

// Of creates a new Label with this key and the supplied value.
func (k *Int) Of(v int) label.Label { return k.Of64(int64(v)) }

// Of64 creates a new Label with this key and the supplied value.
func (k *Int) Of64(v int64) label.Label { return label.Of64(k, uint64(v)) }

// Get returns the label for the key of a label.Map.
func (k *Int) Get(lm label.Map) int64 {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return 0
}

// From returns the value of a Label.
func (k *Int) From(t label.Label) int64 { return int64(t.Unpack64()) }

// Uint is a [label.Key] for unsigned integers.
type Uint struct {
	name        string
	description string
}

// NewUint creates a new [label.Key] for unsigned values.
func NewUint(name, description string) *Uint {
	return &Uint{name: name, description: description}
}

func (k *Uint) Name() string        { return k.name }
func (k *Uint) Description() string { return k.description }

func (k *Uint) Append(buf []byte, l label.Label) []byte {
	return strconv.AppendUint(buf, k.From(l), 10)
}

// Of creates a new Label with this key and the supplied value.
func (k *Uint) Of(v uint64) label.Label { return label.Of64(k, v) }

// Get returns the label for the key of a label.Map.
func (k *Uint) Get(lm label.Map) uint64 {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return 0
}

// From returns the value of a Label.
func (k *Uint) From(t label.Label) uint64 { return t.Unpack64() }

// Float is a label.Key for floating-point values.
type Float struct {
	name        string
	description string
}

// NewFloat creates a new [label.Key] for floating-point values.
func NewFloat(name, description string) *Float {
	return &Float{name: name, description: description}
}

func (k *Float) Name() string        { return k.name }
func (k *Float) Description() string { return k.description }

func (k *Float) Append(buf []byte, l label.Label) []byte {
	return strconv.AppendFloat(buf, k.From(l), 'E', -1, 64)
}

// Of creates a new Label with this key and the supplied value.
func (k *Float) Of(v float64) label.Label {
	return label.Of64(k, math.Float64bits(v))
}

// Get returns the label for the key of a label.Map.
func (k *Float) Get(lm label.Map) float64 {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return 0
}

// From returns the value of a Label.
func (k *Float) From(t label.Label) float64 {
	return math.Float64frombits(t.Unpack64())
}

// String represents a key
type String struct {
	name        string
	description string
}

// NewString creates a new Key for int64 values.
func NewString(name, description string) *String {
	return &String{name: name, description: description}
}

func (k *String) Name() string        { return k.name }
func (k *String) Description() string { return k.description }

func (k *String) Append(buf []byte, l label.Label) []byte {
	return strconv.AppendQuote(buf, k.From(l))
}

// Of creates a new Label with this key and the supplied value.
func (k *String) Of(v string) label.Label { return label.OfString(k, v) }

// Get returns the label for the key of a label.Map.
func (k *String) Get(lm label.Map) string {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return ""
}

// From returns the value of a Label.
func (k *String) From(t label.Label) string { return t.UnpackString() }

// Error represents a key
type Error struct {
	name        string
	description string
}

// NewError returns a new [label.Key] for error values.
func NewError(name, description string) *Error {
	return &Error{name: name, description: description}
}

func (k *Error) Name() string        { return k.name }
func (k *Error) Description() string { return k.description }

func (k *Error) Append(buf []byte, l label.Label) []byte {
	return append(buf, k.From(l).Error()...)
}

// Of returns a new Label with this key and the supplied value.
func (k *Error) Of(v error) label.Label { return label.OfValue(k, v) }

// Get returns the label for the key of a label.Map.
func (k *Error) Get(lm label.Map) error {
	if t := lm.Find(k); t.Valid() {
		return k.From(t)
	}
	return nil
}

// From returns the value of a Label.
func (k *Error) From(t label.Label) error {
	err, _ := t.UnpackValue().(error)
	return err
}


================================================
FILE: internal/event/keys/standard.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package keys

var (
	// Msg is a key used to add message strings to label lists.
	Msg = NewString("message", "a readable message")
	// Label is a key used to indicate an event adds labels to the context.
	Label = NewTag("label", "a label context marker")
	// Start is used for things like traces that have a name.
	Start = NewString("start", "span start")
	// Metric is a key used to indicate an event records metrics.
	End = NewTag("end", "a span end marker")
	// Metric is a key used to indicate an event records metrics.
	Detach = NewTag("detach", "a span detach marker")
	// Err is a key used to add error values to label lists.
	Err = NewError("error", "an error that occurred")
	// Metric is a key used to indicate an event records metrics.
	Metric = NewTag("metric", "a metric event marker")
)


================================================
FILE: internal/event/keys/util.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package keys

import (
	"sort"
	"strings"
)

// Join returns a canonical join of the keys in S:
// a sorted comma-separated string list.
func Join[S ~[]T, T ~string](s S) string {
	strs := make([]string, 0, len(s))
	for _, v := range s {
		strs = append(strs, string(v))
	}
	sort.Strings(strs)
	return strings.Join(strs, ",")
}


================================================
FILE: internal/event/keys/util_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package keys

import "testing"

func TestJoin(t *testing.T) {
	type T string
	type S []T

	tests := []struct {
		data S
		want string
	}{
		{S{"a", "b", "c"}, "a,b,c"},
		{S{"b", "a", "c"}, "a,b,c"},
		{S{"c", "a", "b"}, "a,b,c"},
		{nil, ""},
		{S{}, ""},
	}

	for _, test := range tests {
		if got := Join(test.data); got != test.want {
			t.Errorf("Join(%v) = %q, want %q", test.data, got, test.want)
		}
	}
}


================================================
FILE: internal/event/label/label.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package label

import (
	"fmt"
	"io"
	"slices"
	"unsafe"
)

// Key is used as the identity of a Label.
// Keys are intended to be compared by pointer only, the name should be unique
// for communicating with external systems, but it is not required or enforced.
type Key interface {
	// Name returns the key name.
	Name() string
	// Description returns a string that can be used to describe the value.
	Description() string
	// Append appends the formatted value of the label to the supplied buffer.
	Append(buf []byte, l Label) []byte
}

// Label holds a key and value pair.
// It is normally used when passing around lists of labels.
type Label struct {
	key     Key
	packed  uint64
	untyped any
}

// Map is the interface to a collection of Labels indexed by key.
type Map interface {
	// Find returns the label that matches the supplied key.
	Find(key Key) Label
}

// List is the interface to something that provides an iterable
// list of labels.
// Iteration should start from 0 and continue until Valid returns false.
type List interface {
	// Valid returns true if the index is within range for the list.
	// It does not imply the label at that index will itself be valid.
	Valid(index int) bool
	// Label returns the label at the given index.
	Label(index int) Label
}

// list implements LabelList for a list of Labels.
type list struct {
	labels []Label
}

// filter wraps a LabelList filtering out specific labels.
type filter struct {
	keys       []Key
	underlying List
}

// listMap implements LabelMap for a simple list of labels.
type listMap struct {
	labels []Label
}

// mapChain implements LabelMap for a list of underlying LabelMap.
type mapChain struct {
	maps []Map
}

// OfValue creates a new label from the key and value.
// This method is for implementing new key types, label creation should
// normally be done with the Of method of the key.
func OfValue(k Key, value any) Label { return Label{key: k, untyped: value} }

// UnpackValue assumes the label was built using LabelOfValue and returns the value
// that was passed to that constructor.
// This method is for implementing new key types, for type safety normal
// access should be done with the From method of the key.
func (t Label) UnpackValue() any { return t.untyped }

// Of64 creates a new label from a key and a uint64. This is often
// used for non uint64 values that can be packed into a uint64.
// This method is for implementing new key types, label creation should
// normally be done with the Of method of the key.
func Of64(k Key, v uint64) Label { return Label{key: k, packed: v} }

// Unpack64 assumes the label was built using LabelOf64 and returns the value that
// was passed to that constructor.
// This method is for implementing new key types, for type safety normal
// access should be done with the From method of the key.
func (t Label) Unpack64() uint64 { return t.packed }

type stringptr unsafe.Pointer

// OfString creates a new label from a key and a string.
// This method is for implementing new key types, label creation should
// normally be done with the Of method of the key.
func OfString(k Key, v string) Label {
	return Label{
		key:     k,
		packed:  uint64(len(v)),
		untyped: stringptr(unsafe.StringData(v)),
	}
}

// UnpackString assumes the label was built using LabelOfString and returns the
// value that was passed to that constructor.
// This method is for implementing new key types, for type safety normal
// access should be done with the From method of the key.
func (t Label) UnpackString() string {
	return unsafe.String((*byte)(t.untyped.(stringptr)), int(t.packed))
}

// Valid returns true if the Label is a valid one (it has a key).
func (t Label) Valid() bool { return t.key != nil }

// Key returns the key of this Label.
func (t Label) Key() Key { return t.key }

// Format is used for debug printing of labels.
func (t Label) Format(f fmt.State, r rune) {
	if !t.Valid() {
		io.WriteString(f, `nil`)
		return
	}
	io.WriteString(f, t.Key().Name())
	io.WriteString(f, "=")
	f.Write(t.Key().Append(nil, t)) // ignore error
}

func (l *list) Valid(index int) bool {
	return index >= 0 && index < len(l.labels)
}

func (l *list) Label(index int) Label {
	return l.labels[index]
}

func (f *filter) Valid(index int) bool {
	return f.underlying.Valid(index)
}

func (f *filter) Label(index int) Label {
	l := f.underlying.Label(index)
	if slices.Contains(f.keys, l.Key()) {
		return Label{}
	}
	return l
}

func (lm listMap) Find(key Key) Label {
	for _, l := range lm.labels {
		if l.Key() == key {
			return l
		}
	}
	return Label{}
}

func (c mapChain) Find(key Key) Label {
	for _, src := range c.maps {
		l := src.Find(key)
		if l.Valid() {
			return l
		}
	}
	return Label{}
}

var emptyList = &list{}

func NewList(labels ...Label) List {
	if len(labels) == 0 {
		return emptyList
	}
	return &list{labels: labels}
}

func Filter(l List, keys ...Key) List {
	if len(keys) == 0 {
		return l
	}
	return &filter{keys: keys, underlying: l}
}

func NewMap(labels ...Label) Map {
	return listMap{labels: labels}
}

func MergeMaps(srcs ...Map) Map {
	var nonNil []Map
	for _, src := range srcs {
		if src != nil {
			nonNil = append(nonNil, src)
		}
	}
	if len(nonNil) == 1 {
		return nonNil[0]
	}
	return mapChain{maps: nonNil}
}


================================================
FILE: internal/event/label/label_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package label_test

import (
	"bytes"
	"fmt"
	"runtime"
	"testing"
	"unsafe"

	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

var (
	AKey = keys.NewString("A", "")
	BKey = keys.NewString("B", "")
	CKey = keys.NewString("C", "")
	A    = AKey.Of("a")
	B    = BKey.Of("b")
	C    = CKey.Of("c")
	all  = []label.Label{A, B, C}
)

func TestList(t *testing.T) {
	for _, test := range []struct {
		name   string
		labels []label.Label
		expect string
	}{{
		name: "empty",
	}, {
		name:   "single",
		labels: []label.Label{A},
		expect: `A="a"`,
	}, {
		name:   "invalid",
		labels: []label.Label{{}},
		expect: ``,
	}, {
		name:   "two",
		labels: []label.Label{A, B},
		expect: `A="a", B="b"`,
	}, {
		name:   "three",
		labels: []label.Label{A, B, C},
		expect: `A="a", B="b", C="c"`,
	}, {
		name:   "missing A",
		labels: []label.Label{{}, B, C},
		expect: `B="b", C="c"`,
	}, {
		name:   "missing B",
		labels: []label.Label{A, {}, C},
		expect: `A="a", C="c"`,
	}, {
		name:   "missing C",
		labels: []label.Label{A, B, {}},
		expect: `A="a", B="b"`,
	}, {
		name:   "missing AB",
		labels: []label.Label{{}, {}, C},
		expect: `C="c"`,
	}, {
		name:   "missing AC",
		labels: []label.Label{{}, B, {}},
		expect: `B="b"`,
	}, {
		name:   "missing BC",
		labels: []label.Label{A, {}, {}},
		expect: `A="a"`,
	}} {
		t.Run(test.name, func(t *testing.T) {
			got := printList(label.NewList(test.labels...))
			if got != test.expect {
				t.Errorf("got %q want %q", got, test.expect)
			}
		})
	}
}

func TestFilter(t *testing.T) {
	for _, test := range []struct {
		name    string
		labels  []label.Label
		filters []label.Key
		expect  string
	}{{
		name:   "no filters",
		labels: all,
		expect: `A="a", B="b", C="c"`,
	}, {
		name:    "no labels",
		filters: []label.Key{AKey},
		expect:  ``,
	}, {
		name:    "filter A",
		labels:  all,
		filters: []label.Key{AKey},
		expect:  `B="b", C="c"`,
	}, {
		name:    "filter B",
		labels:  all,
		filters: []label.Key{BKey},
		expect:  `A="a", C="c"`,
	}, {
		name:    "filter C",
		labels:  all,
		filters: []label.Key{CKey},
		expect:  `A="a", B="b"`,
	}, {
		name:    "filter AC",
		labels:  all,
		filters: []label.Key{AKey, CKey},
		expect:  `B="b"`,
	}} {
		t.Run(test.name, func(t *testing.T) {
			labels := label.NewList(test.labels...)
			got := printList(label.Filter(labels, test.filters...))
			if got != test.expect {
				t.Errorf("got %q want %q", got, test.expect)
			}
		})
	}
}

func TestMap(t *testing.T) {
	for _, test := range []struct {
		name   string
		labels []label.Label
		keys   []label.Key
		expect string
	}{{
		name:   "no labels",
		keys:   []label.Key{AKey},
		expect: `nil`,
	}, {
		name:   "match A",
		labels: all,
		keys:   []label.Key{AKey},
		expect: `A="a"`,
	}, {
		name:   "match B",
		labels: all,
		keys:   []label.Key{BKey},
		expect: `B="b"`,
	}, {
		name:   "match C",
		labels: all,
		keys:   []label.Key{CKey},
		expect: `C="c"`,
	}, {
		name:   "match ABC",
		labels: all,
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", C="c"`,
	}, {
		name:   "missing A",
		labels: []label.Label{{}, B, C},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `nil, B="b", C="c"`,
	}, {
		name:   "missing B",
		labels: []label.Label{A, {}, C},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", nil, C="c"`,
	}, {
		name:   "missing C",
		labels: []label.Label{A, B, {}},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", nil`,
	}} {
		t.Run(test.name, func(t *testing.T) {
			lm := label.NewMap(test.labels...)
			got := printMap(lm, test.keys)
			if got != test.expect {
				t.Errorf("got %q want %q", got, test.expect)
			}
		})
	}
}

func TestMapMerge(t *testing.T) {
	for _, test := range []struct {
		name   string
		maps   []label.Map
		keys   []label.Key
		expect string
	}{{
		name:   "no maps",
		keys:   []label.Key{AKey},
		expect: `nil`,
	}, {
		name:   "one map",
		maps:   []label.Map{label.NewMap(all...)},
		keys:   []label.Key{AKey},
		expect: `A="a"`,
	}, {
		name:   "invalid map",
		maps:   []label.Map{label.NewMap()},
		keys:   []label.Key{AKey},
		expect: `nil`,
	}, {
		name:   "two maps",
		maps:   []label.Map{label.NewMap(B, C), label.NewMap(A)},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", C="c"`,
	}, {
		name:   "invalid start map",
		maps:   []label.Map{label.NewMap(), label.NewMap(B, C)},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `nil, B="b", C="c"`,
	}, {
		name:   "invalid mid map",
		maps:   []label.Map{label.NewMap(A), label.NewMap(), label.NewMap(C)},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", nil, C="c"`,
	}, {
		name:   "invalid end map",
		maps:   []label.Map{label.NewMap(A, B), label.NewMap()},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", nil`,
	}, {
		name:   "three maps one nil",
		maps:   []label.Map{label.NewMap(A), label.NewMap(B), nil},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", nil`,
	}, {
		name:   "two maps one nil",
		maps:   []label.Map{label.NewMap(A, B), nil},
		keys:   []label.Key{AKey, BKey, CKey},
		expect: `A="a", B="b", nil`,
	}} {
		t.Run(test.name, func(t *testing.T) {
			tagMap := label.MergeMaps(test.maps...)
			got := printMap(tagMap, test.keys)
			if got != test.expect {
				t.Errorf("got %q want %q", got, test.expect)
			}
		})
	}
}

func printList(list label.List) string {
	buf := &bytes.Buffer{}
	for index := 0; list.Valid(index); index++ {
		l := list.Label(index)
		if !l.Valid() {
			continue
		}
		if buf.Len() > 0 {
			buf.WriteString(", ")
		}
		fmt.Fprint(buf, l)
	}
	return buf.String()
}

func printMap(lm label.Map, keys []label.Key) string {
	buf := &bytes.Buffer{}
	for _, key := range keys {
		if buf.Len() > 0 {
			buf.WriteString(", ")
		}
		fmt.Fprint(buf, lm.Find(key))
	}
	return buf.String()
}

func TestAttemptedStringCorruption(t *testing.T) {
	defer func() {
		r := recover()
		if _, ok := r.(*runtime.TypeAssertionError); !ok {
			t.Fatalf("wanted to recover TypeAssertionError, got %T", r)
		}
	}()

	var x uint64 = 12390
	p := unsafe.Pointer(&x)
	l := label.OfValue(AKey, p)
	_ = l.UnpackString()
}


================================================
FILE: internal/expect/expect.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package expect provides support for interpreting structured comments in Go
source code (including go.mod and go.work files) as test expectations.

This is primarily intended for writing tests of things that process Go source
files, although it does not directly depend on the testing package.

Collect notes with the Extract or Parse functions, and use the
MatchBefore function to find matches within the lines the comments were on.

The interpretation of the notes depends on the application.
For example, the test suite for a static checking tool might
use a @diag note to indicate an expected diagnostic:

	fmt.Printf("%s", 1) //@ diag("%s wants a string, got int")

By contrast, the test suite for a source code navigation tool
might use notes to indicate the positions of features of
interest, the actions to be performed by the test,
and their expected outcomes:

	var x = 1 //@ x_decl
	...
	print(x) //@ definition("x", x_decl)
	print(x) //@ typeof("x", "int")

# Note comment syntax

Note comments always start with the special marker @, which must be the
very first character after the comment opening pair, so //@ or /*@ with no
spaces.

This is followed by a comma separated list of notes.

A note always starts with an identifier, which is optionally followed by an
argument list. The argument list is surrounded with parentheses and contains a
comma-separated list of arguments.
The empty parameter list and the missing parameter list are distinguishable if
needed; they result in a nil or an empty list in the Args parameter respectively.

Arguments may be positional, such as f(value), or named, such as f(name=value).
Positional arguments must appear before named arguments.
Names may not be repeated.

Argument values may be either identifiers or literals.
The literals supported are the basic value literals, of string, float, integer
true, false or nil. All the literals match the standard go conventions, with
all bases of integers, and both quote and backtick strings.
There is one extra literal type, which is a string literal preceded by the
identifier "re" which is compiled to a regular expression.
*/
package expect

import (
	"bytes"
	"fmt"
	"go/token"
	"regexp"
)

// Note is a parsed note from an expect comment.
// It knows the position of the start of the comment, and the name and
// arguments that make up the note.
type Note struct {
	Pos       token.Pos      // The position at which the note identifier appears
	Name      string         // the name associated with the note
	Args      []any          // positional arguments (non-nil if parens were present)
	NamedArgs map[string]any // named arguments (or nil if none)
}

// ReadFile is the type of a function that can provide file contents for a
// given filename.
// This is used in MatchBefore to look up the content of the file in order to
// find the line to match the pattern against.
type ReadFile func(filename string) ([]byte, error)

// MatchBefore attempts to match a pattern in the line before the supplied pos.
// It uses the token.File and the ReadFile to work out the contents of the line
// that end is part of, and then matches the pattern against the content of the
// start of that line up to the supplied position.
// The pattern may be either a simple string, []byte or a *regexp.Regexp.
// MatchBefore returns the range of the line that matched the pattern, and
// invalid positions if there was no match, or an error if the line could not be
// found.
func MatchBefore(f *token.File, readFile ReadFile, end token.Pos, pattern any) (token.Pos, token.Pos, error) {
	content, err := readFile(f.Name())
	if err != nil {
		return token.NoPos, token.NoPos, fmt.Errorf("invalid file: %v", err)
	}
	position := f.Position(end)
	startOffset := f.Offset(f.LineStart(position.Line))
	endOffset := f.Offset(end)
	line := content[startOffset:endOffset]
	matchStart, matchEnd := -1, -1
	switch pattern := pattern.(type) {
	case string:
		bytePattern := []byte(pattern)
		matchStart = bytes.Index(line, bytePattern)
		if matchStart >= 0 {
			matchEnd = matchStart + len(bytePattern)
		}
	case []byte:
		matchStart = bytes.Index(line, pattern)
		if matchStart >= 0 {
			matchEnd = matchStart + len(pattern)
		}
	case *regexp.Regexp:
		match := pattern.FindIndex(line)
		if len(match) > 0 {
			matchStart = match[0]
			matchEnd = match[1]
		}
	}
	if matchStart < 0 {
		return token.NoPos, token.NoPos, nil
	}
	return f.Pos(startOffset + matchStart), f.Pos(startOffset + matchEnd), nil
}


================================================
FILE: internal/expect/expect_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package expect_test

import (
	"bytes"
	"go/token"
	"os"
	"reflect"
	"slices"
	"testing"

	"golang.org/x/tools/internal/expect"
)

func TestMarker(t *testing.T) {
	for _, tt := range []struct {
		filename      string
		expectNotes   int
		expectMarkers map[string]string
		expectChecks  map[string][]any
		// expectChecks holds {"id": values} for each call check(id, values...).
		// Any named k=v arguments become a final map[string]any argument.
	}{
		{
			filename:    "testdata/test.go",
			expectNotes: 14,
			expectMarkers: map[string]string{
				"αSimpleMarker": "α",
				"OffsetMarker":  "β",
				"RegexMarker":   "γ",
				"εMultiple":     "ε",
				"ζMarkers":      "ζ",
				"ηBlockMarker":  "η",
				"Declared":      "η",
				"Comment":       "ι",
				"LineComment":   "someFunc",
				"NonIdentifier": "+",
				"StringMarker":  "\"hello\"",
			},
			expectChecks: map[string][]any{
				"αSimpleMarker": nil,
				"StringAndInt":  {"Number %d", int64(12)},
				"Bool":          {true},
				"NamedArgs": {int64(1), true, expect.Identifier("a"), map[string]any{
					"b": int64(1),
					"c": "3",
					"d": true,
				}},
			},
		},
		{
			filename:    "testdata/go.fake.mod",
			expectNotes: 2,
			expectMarkers: map[string]string{
				"αMarker": "αfake1α",
				"βMarker": "require golang.org/modfile v0.0.0",
			},
		},
		{
			filename:    "testdata/go.fake.work",
			expectNotes: 2,
			expectMarkers: map[string]string{
				"αMarker": "1.23.0",
				"βMarker": "αβ",
			},
		},
	} {
		t.Run(tt.filename, func(t *testing.T) {
			content, err := os.ReadFile(tt.filename)
			if err != nil {
				t.Fatal(err)
			}
			readFile := func(string) ([]byte, error) { return content, nil }

			markers := make(map[string]token.Pos)
			for name, tok := range tt.expectMarkers {
				offset := bytes.Index(content, []byte(tok))
				markers[name] = token.Pos(offset + 1)
				end := bytes.Index(content[offset:], []byte(tok))
				if end > 0 {
					markers[name+"@"] = token.Pos(offset + end + 2)
				}
			}

			fset := token.NewFileSet()
			notes, err := expect.Parse(fset, tt.filename, content)
			if err != nil {
				t.Fatalf("Failed to extract notes:\n%v", err)
			}
			if len(notes) != tt.expectNotes {
				t.Errorf("Expected %v notes, got %v", tt.expectNotes, len(notes))
			}
			for _, n := range notes {
				switch {
				case n.Args == nil:
					// A //@foo note associates the name foo with the position of the
					// first match of "foo" on the current line.
					checkMarker(t, fset, readFile, markers, n.Pos, n.Name, n.Name)
				case n.Name == "mark":
					// A //@mark(name, "pattern") note associates the specified name
					// with the position on the first match of pattern on the current line.
					if len(n.Args) != 2 {
						t.Errorf("%v: expected 2 args to mark, got %v", fset.Position(n.Pos), len(n.Args))
						continue
					}
					ident, ok := n.Args[0].(expect.Identifier)
					if !ok {
						t.Errorf("%v: got %v (%T), want identifier", fset.Position(n.Pos), n.Args[0], n.Args[0])
						continue
					}
					checkMarker(t, fset, readFile, markers, n.Pos, string(ident), n.Args[1])

				case n.Name == "check":
					// A //@check(args, ...) note specifies some hypothetical action to
					// be taken by the test driver and its expected outcome.
					// In this test, the action is to compare the arguments
					// against expectChecks.
					if len(n.Args) < 1 {
						t.Errorf("%v: expected 1 args to check, got %v", fset.Position(n.Pos), len(n.Args))
						continue
					}
					ident, ok := n.Args[0].(expect.Identifier)
					if !ok {
						t.Errorf("%v: got %v (%T), want identifier", fset.Position(n.Pos), n.Args[0], n.Args[0])
						continue
					}
					wantArgs, ok := tt.expectChecks[string(ident)]
					if !ok {
						t.Errorf("%v: unexpected check %v", fset.Position(n.Pos), ident)
						continue
					}
					gotArgs := n.Args[1:]
					if n.NamedArgs != nil {
						// Clip to avoid mutating Args' array.
						gotArgs = append(slices.Clip(gotArgs), n.NamedArgs)
					}

					if len(gotArgs) != len(wantArgs) {
						t.Errorf("%v: expected %v args to check, got %v", fset.Position(n.Pos), len(wantArgs), len(gotArgs))
						continue
					}
					for i := range gotArgs {
						if !reflect.DeepEqual(wantArgs[i], gotArgs[i]) {
							t.Errorf("%v: arg %d: expected %#v, got %#v", fset.Position(n.Pos), i+1, wantArgs[i], gotArgs[i])
						}
					}
				default:
					t.Errorf("Unexpected note %v at %v", n.Name, fset.Position(n.Pos))
				}
			}
		})
	}
}

func checkMarker(t *testing.T, fset *token.FileSet, readFile expect.ReadFile, markers map[string]token.Pos, pos token.Pos, name string, pattern any) {
	start, end, err := expect.MatchBefore(fset.File(pos), readFile, pos, pattern)
	if err != nil {
		t.Errorf("%v: MatchBefore failed: %v", fset.Position(pos), err)
		return
	}
	if start == token.NoPos {
		t.Errorf("%v: Pattern %v did not match", fset.Position(pos), pattern)
		return
	}
	expectStart, ok := markers[name]
	if !ok {
		t.Errorf("%v: unexpected marker %v", fset.Position(pos), name)
		return
	}
	if start != expectStart {
		t.Errorf("%v: Expected %v got %v", fset.Position(pos), fset.Position(expectStart), fset.Position(start))
	}
	if expectEnd, ok := markers[name+"@"]; ok && end != expectEnd {
		t.Errorf("%v: Expected end %v got %v", fset.Position(pos), fset.Position(expectEnd), fset.Position(end))
	}
}


================================================
FILE: internal/expect/extract.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package expect

import (
	"fmt"
	"go/ast"
	"go/parser"
	goscanner "go/scanner"
	"go/token"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"text/scanner"

	"golang.org/x/mod/modfile"
)

const commentStart = "@"
const commentStartLen = len(commentStart)

// Identifier is the type for an identifier in a Note argument list.
type Identifier string

// Parse collects all the notes present in a file.
// If content is nil, the filename specified is read and parsed, otherwise the
// content is used and the filename is used for positions and error messages.
// Each comment whose text starts with @ is parsed as a comma-separated
// sequence of notes.
// See the package documentation for details about the syntax of those
// notes.
func Parse(fset *token.FileSet, filename string, content []byte) ([]*Note, error) {
	if content == nil {
		data, err := os.ReadFile(filename)
		if err != nil {
			return nil, err
		}
		content = data
	}

	switch filepath.Ext(filename) {
	case ".s":
		// The assembler uses a custom scanner,
		// but the go/scanner package is close
		// enough: we only want the comments.
		file := fset.AddFile(filename, -1, len(content))
		var scan goscanner.Scanner
		scan.Init(file, content, nil, goscanner.ScanComments)

		var notes []*Note
		for {
			pos, tok, lit := scan.Scan()
			if tok == token.EOF {
				break
			}
			if tok == token.COMMENT {
				text, adjust := getAdjustedNote(lit)
				if text == "" {
					continue
				}
				parsed, err := parse(file, pos+token.Pos(adjust), text)
				if err != nil {
					return nil, err
				}
				notes = append(notes, parsed...)
			}
		}
		return notes, nil

	case ".go":
		// TODO: We should write this in terms of the scanner, like the .s case above.
		// there are ways you can break the parser such that it will not add all the
		// comments to the ast, which may result in files where the tests are silently
		// not run.
		file, err := parser.ParseFile(fset, filename, content, parser.ParseComments|parser.AllErrors|parser.SkipObjectResolution)
		if file == nil {
			return nil, err
		}
		return ExtractGo(fset.File(file.Pos()), file)

	case ".mod":
		file, err := modfile.Parse(filename, content, nil)
		if err != nil {
			return nil, err
		}
		f := fset.AddFile(filename, -1, len(content))
		f.SetLinesForContent(content)
		notes, err := extractModWork(fset, file.Syntax.Stmt)
		if err != nil {
			return nil, err
		}
		// Since modfile.Parse does not return an *ast, we need to add the offset
		// within the file's contents to the file's base relative to the fileset.
		for _, note := range notes {
			note.Pos += token.Pos(f.Base())
		}
		return notes, nil

	case ".work":
		file, err := modfile.ParseWork(filename, content, nil)
		if err != nil {
			return nil, err
		}
		f := fset.AddFile(filename, -1, len(content))
		f.SetLinesForContent(content)
		notes, err := extractModWork(fset, file.Syntax.Stmt)
		if err != nil {
			return nil, err
		}
		// As with go.mod files, we need to compute a synthetic token.Pos.
		for _, note := range notes {
			note.Pos += token.Pos(f.Base())
		}
		return notes, nil
	}
	return nil, nil
}

// extractModWork collects all the notes present in a go.mod file or go.work
// file, by way of the shared modfile.Expr statement node.
//
// Each comment whose text starts with @ is parsed as a comma-separated
// sequence of notes.
// See the package documentation for details about the syntax of those
// notes.
// Only allow notes to appear with the following format: "//@mark()" or // @mark()
func extractModWork(fset *token.FileSet, exprs []modfile.Expr) ([]*Note, error) {
	var notes []*Note
	for _, stmt := range exprs {
		comment := stmt.Comment()
		if comment == nil {
			continue
		}
		var allComments []modfile.Comment
		allComments = append(allComments, comment.Before...)
		allComments = append(allComments, comment.Suffix...)
		for _, cmt := range allComments {
			text, adjust := getAdjustedNote(cmt.Token)
			if text == "" {
				continue
			}
			pos := token.Pos(int(cmt.Start.Byte) + adjust)
			parsed, err := parse(fset.File(pos), pos, text)
			if err != nil {
				return nil, err
			}
			notes = append(notes, parsed...)
		}
	}
	return notes, nil
}

// ExtractGo collects all the notes present in an AST.
// Each comment whose text starts with @ is parsed as a comma-separated
// sequence of notes.
// See the package documentation for details about the syntax of those
// notes.
func ExtractGo(tokFile *token.File, file *ast.File) ([]*Note, error) {
	var notes []*Note
	for _, g := range file.Comments {
		for _, c := range g.List {
			text, adjust := getAdjustedNote(c.Text)
			if text == "" {
				continue
			}
			parsed, err := parse(tokFile, token.Pos(int(c.Pos())+adjust), text)
			if err != nil {
				return nil, err
			}
			notes = append(notes, parsed...)
		}
	}
	return notes, nil
}

func getAdjustedNote(text string) (string, int) {
	if strings.HasPrefix(text, "/*") {
		text = strings.TrimSuffix(text, "*/")
	}
	text = text[2:] // remove "//" or "/*" prefix

	// Allow notes to appear within comments.
	// For example:
	// "// //@mark()" is valid.
	// "// @mark()" is not valid.
	// "// /*@mark()*/" is not valid.
	var adjust int
	if i := strings.Index(text, commentStart); i > 2 {
		// Get the text before the commentStart.
		pre := text[i-2 : i]
		if pre != "//" {
			return "", 0
		}
		text = text[i:]
		adjust = i
	}
	if !strings.HasPrefix(text, commentStart) {
		return "", 0
	}
	text = text[commentStartLen:]
	return text, commentStartLen + adjust + 1
}

const invalidToken rune = 0

type tokens struct {
	scanner scanner.Scanner
	current rune
	err     error
	base    token.Pos
}

func (t *tokens) Init(base token.Pos, text string) *tokens {
	t.base = base
	t.scanner.Init(strings.NewReader(text))
	t.scanner.Mode = scanner.GoTokens
	t.scanner.Whitespace ^= 1 << '\n' // don't skip new lines
	t.scanner.Error = func(s *scanner.Scanner, msg string) {
		t.Errorf("%v", msg)
	}
	return t
}

func (t *tokens) Consume() string {
	t.current = invalidToken
	return t.scanner.TokenText()
}

func (t *tokens) Token() rune {
	if t.err != nil {
		return scanner.EOF
	}
	if t.current == invalidToken {
		t.current = t.scanner.Scan()
	}
	return t.current
}

func (t *tokens) Skip(r rune) int {
	i := 0
	for t.Token() == '\n' {
		t.Consume()
		i++
	}
	return i
}

func (t *tokens) TokenString() string {
	return scanner.TokenString(t.Token())
}

func (t *tokens) Pos() token.Pos {
	return t.base + token.Pos(t.scanner.Position.Offset)
}

func (t *tokens) Errorf(msg string, args ...any) {
	if t.err != nil {
		return
	}
	t.err = fmt.Errorf(msg, args...)
}

func parse(tokFile *token.File, base token.Pos, text string) ([]*Note, error) {
	t := new(tokens).Init(base, text)
	notes := parseComment(t)
	if t.err != nil {
		return nil, fmt.Errorf("%v: %s", tokFile.Position(t.Pos()), t.err)
	}
	return notes, nil
}

func parseComment(t *tokens) []*Note {
	var notes []*Note
	for {
		t.Skip('\n')
		switch t.Token() {
		case scanner.EOF:
			return notes
		case scanner.Ident:
			notes = append(notes, parseNote(t))
		default:
			t.Errorf("unexpected %s parsing comment, expect identifier", t.TokenString())
			return nil
		}
		switch t.Token() {
		case scanner.EOF:
			return notes
		case ',', '\n':
			t.Consume()
		default:
			t.Errorf("unexpected %s parsing comment, expect separator", t.TokenString())
			return nil
		}
	}
}

func parseNote(t *tokens) *Note {
	n := &Note{
		Pos:  t.Pos(),
		Name: t.Consume(),
	}

	switch t.Token() {
	case ',', '\n', scanner.EOF:
		// no argument list present
		return n
	case '(':
		n.Args, n.NamedArgs = parseArgumentList(t)
		return n
	default:
		t.Errorf("unexpected %s parsing note", t.TokenString())
		return nil
	}
}

func parseArgumentList(t *tokens) (args []any, named map[string]any) {
	args = []any{} // @name() is represented by a non-nil empty slice.
	t.Consume()    // '('
	t.Skip('\n')
	for t.Token() != ')' {
		name, arg := parseArgument(t)
		if name != "" {
			// f(k=v)
			if named == nil {
				named = make(map[string]any)
			}
			if _, dup := named[name]; dup {
				t.Errorf("duplicate named argument %q", name)
				return nil, nil
			}
			named[name] = arg
		} else {
			// f(v)
			if named != nil {
				t.Errorf("positional argument follows named argument")
				return nil, nil
			}
			args = append(args, arg)
		}
		if t.Token() != ',' {
			break
		}
		t.Consume()
		t.Skip('\n')
	}
	if t.Token() != ')' {
		t.Errorf("unexpected %s parsing argument list", t.TokenString())
		return nil, nil
	}
	t.Consume() // ')'
	return args, named
}

// parseArgument returns the value of the argument ("f(value)"),
// and its name if named "f(name=value)".
func parseArgument(t *tokens) (name string, value any) {
again:
	switch t.Token() {
	case scanner.Ident:
		v := t.Consume()
		switch v {
		case "true":
			value = true
		case "false":
			value = false
		case "nil":
			value = nil
		case "re":
			if t.Token() != scanner.String && t.Token() != scanner.RawString {
				t.Errorf("re must be followed by string, got %s", t.TokenString())
				return
			}
			pattern, _ := strconv.Unquote(t.Consume()) // can't fail
			re, err := regexp.Compile(pattern)
			if err != nil {
				t.Errorf("invalid regular expression %s: %v", pattern, err)
				return
			}
			value = re
		default:
			// f(name=value)?
			if name == "" && t.Token() == '=' {
				t.Consume() // '='
				name = v
				goto again
			}
			value = Identifier(v)
		}

	case scanner.String, scanner.RawString:
		value, _ = strconv.Unquote(t.Consume()) // can't fail

	case scanner.Int:
		s := t.Consume()
		v, err := strconv.ParseInt(s, 0, 0)
		if err != nil {
			t.Errorf("cannot convert %v to int: %v", s, err)
		}
		value = v

	case scanner.Float:
		s := t.Consume()
		v, err := strconv.ParseFloat(s, 64)
		if err != nil {
			t.Errorf("cannot convert %v to float: %v", s, err)
		}
		value = v

	case '-':
		t.Consume()
		switch t.Token() {
		case scanner.Int:
			s := "-" + t.Consume()
			v, err := strconv.ParseInt(s, 0, 0)
			if err != nil {
				t.Errorf("cannot convert %v to int: %v", s, err)
			}
			value = v

		case scanner.Float:
			s := "-" + t.Consume()
			v, err := strconv.ParseFloat(s, 64)
			if err != nil {
				t.Errorf("cannot convert %v to float: %v", s, err)
			}
			value = v

		default:
			t.Errorf("unexpected '-' not followed by number, got %s", t.TokenString())
		}

	case scanner.Char:
		t.Errorf("unexpected char literal %s", t.Consume())

	default:
		t.Errorf("unexpected %s parsing argument", t.TokenString())
	}
	return
}


================================================
FILE: internal/expect/testdata/go.fake.mod
================================================
// This file is named go.fake.mod so it does not define a real module, which
// would make the contents of this directory unavailable to the test when run
// from outside the repository.

module αfake1α //@mark(αMarker, "αfake1α")

go 1.14

require golang.org/modfile v0.0.0 //@mark(βMarker, "require golang.org/modfile v0.0.0")


================================================
FILE: internal/expect/testdata/go.fake.work
================================================
// This file is named go.fake.mod so it does not define a real module, which
// would make the contents of this directory unavailable to the test when run
// from outside the repository.

go 1.23.0 //@mark(αMarker, "1.23.0")

use ./αβ //@mark(βMarker, "αβ")


================================================
FILE: internal/expect/testdata/test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fake1 is used to test the expect package.
package fake1

// The greek letters in this file mark points we use for marker tests.
// We use unique markers so we can make the tests stable against changes to
// this file.

const (
	_                   int = iota
	αSimpleMarkerα          //@αSimpleMarker
	offsetββMarker          //@mark(OffsetMarker, "β")
	regexγMaγrker           //@mark(RegexMarker, re`\p{Greek}Ma`)
	εMultipleεζMarkersζ     //@εMultiple,ζMarkers
	ηBlockMarkerη           /*@ηBlockMarker*/
)

/*Marker ι inside ι a comment*/ //@mark(Comment,"ι inside ")
var x = "hello"                 //@mark(StringMarker, `"hello"`)

// someFunc is a function. //@mark(LineComment, "someFunc")
func someFunc(a, b int) int {
	// The line below must be the first occurrence of the plus operator
	return a + b + 1 //@mark(NonIdentifier, re`\+[^\+]*`)
}

// And some extra checks for interesting action parameters
// Also checks for multi-line expectations
/*@
check(αSimpleMarker)
check(StringAndInt,
	"Number %d",
	12,
)

check(Bool, true)

check(NamedArgs, 1, true, a, b=1, c="3", d=true)
*/


================================================
FILE: internal/facts/facts.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package facts defines a serializable set of analysis.Fact.
//
// It provides a partial implementation of the Fact-related parts of the
// analysis.Pass interface for use in analysis drivers such as "go vet"
// and other build systems.
//
// The serial format is unspecified and may change, so the same version
// of this package must be used for reading and writing serialized facts.
//
// The handling of facts in the analysis system parallels the handling
// of type information in the compiler: during compilation of package P,
// the compiler emits an export data file that describes the type of
// every object (named thing) defined in package P, plus every object
// indirectly reachable from one of those objects. Thus the downstream
// compiler of package Q need only load one export data file per direct
// import of Q, and it will learn everything about the API of package P
// and everything it needs to know about the API of P's dependencies.
//
// Similarly, analysis of package P emits a fact set containing facts
// about all objects exported from P, plus additional facts about only
// those objects of P's dependencies that are reachable from the API of
// package P; the downstream analysis of Q need only load one fact set
// per direct import of Q.
//
// The notion of "exportedness" that matters here is that of the
// compiler. According to the language spec, a method pkg.T.f is
// unexported simply because its name starts with lowercase. But the
// compiler must nonetheless export f so that downstream compilations can
// accurately ascertain whether pkg.T implements an interface pkg.I
// defined as interface{f()}. Exported thus means "described in export
// data".
package facts

import (
	"bytes"
	"encoding/gob"
	"fmt"
	"go/types"
	"io"
	"log"
	"reflect"
	"sort"
	"sync"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/types/objectpath"
)

const debug = false

// A Set is a set of analysis.Facts.
//
// Decode creates a Set of facts by reading from the imports of a given
// package, and Encode writes out the set. Between these operation,
// the Import and Export methods will query and update the set.
//
// All of Set's methods except String are safe to call concurrently.
type Set struct {
	pkg *types.Package
	mu  sync.Mutex
	m   map[key]analysis.Fact
}

type key struct {
	pkg *types.Package
	obj types.Object // (object facts only)
	t   reflect.Type
}

// ImportObjectFact implements analysis.Pass.ImportObjectFact.
func (s *Set) ImportObjectFact(obj types.Object, ptr analysis.Fact) bool {
	if obj == nil {
		panic("nil object")
	}
	key := key{pkg: obj.Pkg(), obj: obj, t: reflect.TypeOf(ptr)}
	s.mu.Lock()
	defer s.mu.Unlock()
	if v, ok := s.m[key]; ok {
		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
		return true
	}
	return false
}

// ExportObjectFact implements analysis.Pass.ExportObjectFact.
func (s *Set) ExportObjectFact(obj types.Object, fact analysis.Fact) {
	if obj.Pkg() != s.pkg {
		log.Panicf("in package %s: ExportObjectFact(%s, %T): can't set fact on object belonging another package",
			s.pkg, obj, fact)
	}
	key := key{pkg: obj.Pkg(), obj: obj, t: reflect.TypeOf(fact)}
	s.mu.Lock()
	s.m[key] = fact // clobber any existing entry
	s.mu.Unlock()
}

func (s *Set) AllObjectFacts(filter map[reflect.Type]bool) []analysis.ObjectFact {
	var facts []analysis.ObjectFact
	s.mu.Lock()
	for k, v := range s.m {
		if k.obj != nil && filter[k.t] {
			facts = append(facts, analysis.ObjectFact{Object: k.obj, Fact: v})
		}
	}
	s.mu.Unlock()
	return facts
}

// ImportPackageFact implements analysis.Pass.ImportPackageFact.
func (s *Set) ImportPackageFact(pkg *types.Package, ptr analysis.Fact) bool {
	if pkg == nil {
		panic("nil package")
	}
	key := key{pkg: pkg, t: reflect.TypeOf(ptr)}
	s.mu.Lock()
	defer s.mu.Unlock()
	if v, ok := s.m[key]; ok {
		reflect.ValueOf(ptr).Elem().Set(reflect.ValueOf(v).Elem())
		return true
	}
	return false
}

// ExportPackageFact implements analysis.Pass.ExportPackageFact.
func (s *Set) ExportPackageFact(fact analysis.Fact) {
	key := key{pkg: s.pkg, t: reflect.TypeOf(fact)}
	s.mu.Lock()
	s.m[key] = fact // clobber any existing entry
	s.mu.Unlock()
}

func (s *Set) AllPackageFacts(filter map[reflect.Type]bool) []analysis.PackageFact {
	var facts []analysis.PackageFact
	s.mu.Lock()
	for k, v := range s.m {
		if k.obj == nil && filter[k.t] {
			facts = append(facts, analysis.PackageFact{Package: k.pkg, Fact: v})
		}
	}
	s.mu.Unlock()
	return facts
}

// gobFact is the Gob declaration of a serialized fact.
type gobFact struct {
	PkgPath string          // path of package
	Object  objectpath.Path // optional path of object relative to package itself
	Fact    analysis.Fact   // type and value of user-defined Fact
}

// A Decoder decodes the facts from the direct imports of the package
// provided to NewEncoder. A single decoder may be used to decode
// multiple fact sets (e.g. each for a different set of fact types)
// for the same package. Each call to Decode returns an independent
// fact set.
type Decoder struct {
	pkg        *types.Package
	getPackage GetPackageFunc
}

// NewDecoder returns a fact decoder for the specified package.
//
// It uses a brute-force recursive approach to enumerate all objects
// defined by dependencies of pkg, so that it can learn the set of
// package paths that may be mentioned in the fact encoding. This does
// not scale well; use [NewDecoderFunc] where possible.
func NewDecoder(pkg *types.Package) *Decoder {
	// Compute the import map for this package.
	// See the package doc comment.
	m := importMap(pkg.Imports())
	getPackageFunc := func(path string) *types.Package { return m[path] }
	return NewDecoderFunc(pkg, getPackageFunc)
}

// NewDecoderFunc returns a fact decoder for the specified package.
//
// It calls the getPackage function for the package path string of
// each dependency (perhaps indirect) that it encounters in the
// encoding. If the function returns nil, the fact is discarded.
//
// This function is preferred over [NewDecoder] when the client is
// capable of efficient look-up of packages by package path.
func NewDecoderFunc(pkg *types.Package, getPackage GetPackageFunc) *Decoder {
	return &Decoder{
		pkg:        pkg,
		getPackage: getPackage,
	}
}

// A GetPackageFunc function returns the package denoted by a package path.
type GetPackageFunc = func(pkgPath string) *types.Package

// Decode decodes all the facts relevant to the analysis of package
// pkgPath. The read function reads serialized fact data from an external
// source for one of pkg's direct imports, identified by package path.
// The empty file is a valid encoding of an empty fact set.
//
// It is the caller's responsibility to call gob.Register on all
// necessary fact types.
//
// Concurrent calls to Decode are safe, so long as the
// [GetPackageFunc] (if any) is also concurrency-safe.
func (d *Decoder) Decode(read func(pkgPath string) ([]byte, error)) (*Set, error) {
	// Read facts from imported packages.
	// Facts may describe indirectly imported packages, or their objects.
	m := make(map[key]analysis.Fact) // one big bucket
	for _, imp := range d.pkg.Imports() {
		logf := func(format string, args ...any) {
			if debug {
				prefix := fmt.Sprintf("in %s, importing %s: ",
					d.pkg.Path(), imp.Path())
				log.Print(prefix, fmt.Sprintf(format, args...))
			}
		}

		// Read the gob-encoded facts.
		data, err := read(imp.Path())
		if err != nil {
			return nil, fmt.Errorf("in %s, can't import facts for package %q: %v",
				d.pkg.Path(), imp.Path(), err)
		}
		if len(data) == 0 {
			continue // no facts
		}
		var gobFacts []gobFact
		if err := gob.NewDecoder(bytes.NewReader(data)).Decode(&gobFacts); err != nil {
			return nil, fmt.Errorf("decoding facts for %q: %v", imp.Path(), err)
		}
		logf("decoded %d facts: %v", len(gobFacts), gobFacts)

		// Parse each one into a key and a Fact.
		for _, f := range gobFacts {
			factPkg := d.getPackage(f.PkgPath) // possibly an indirect dependency
			if factPkg == nil {
				// Fact relates to a dependency that was
				// unused in this translation unit. Skip.
				logf("no package %q; discarding %v", f.PkgPath, f.Fact)
				continue
			}
			key := key{pkg: factPkg, t: reflect.TypeOf(f.Fact)}
			if f.Object != "" {
				// object fact
				obj, err := objectpath.Object(factPkg, f.Object)
				if err != nil {
					// (most likely due to unexported object)
					// TODO(adonovan): audit for other possibilities.
					logf("no object for path: %v; discarding %s", err, f.Fact)
					continue
				}
				key.obj = obj
				logf("read %T fact %s for %v", f.Fact, f.Fact, key.obj)
			} else {
				// package fact
				logf("read %T fact %s for %v", f.Fact, f.Fact, factPkg)
			}
			m[key] = f.Fact
		}
	}

	return &Set{pkg: d.pkg, m: m}, nil
}

// Encode encodes a set of facts to a memory buffer.
//
// It may fail if one of the Facts could not be gob-encoded, but this is
// a sign of a bug in an Analyzer.
func (s *Set) Encode() []byte {
	encoder := new(objectpath.Encoder)

	// TODO(adonovan): opt: use a more efficient encoding
	// that avoids repeating PkgPath for each fact.

	// Gather all facts, including those from imported packages.
	var gobFacts []gobFact

	s.mu.Lock()
	for k, fact := range s.m {
		if debug {
			log.Printf("%v => %s\n", k, fact)
		}

		// Don't export facts that we imported from another
		// package, unless they represent fields or methods,
		// or package-level types.
		// (Facts about packages, and other package-level
		// objects, are only obtained from direct imports so
		// they needn't be reexported.)
		//
		// This is analogous to the pruning done by "deep"
		// export data for types, but not as precise because
		// we aren't careful about which structs or methods
		// we rexport: it should be only those referenced
		// from the API of s.pkg.
		// TODO(adonovan): opt: be more precise. e.g.
		// intersect with the set of objects computed by
		// importMap(s.pkg.Imports()).
		// TODO(adonovan): opt: implement "shallow" facts.
		if k.pkg != s.pkg {
			if k.obj == nil {
				continue // imported package fact
			}
			if _, isType := k.obj.(*types.TypeName); !isType &&
				k.obj.Parent() == k.obj.Pkg().Scope() {
				continue // imported fact about package-level non-type object
			}
		}

		var object objectpath.Path
		if k.obj != nil {
			path, err := encoder.For(k.obj)
			if err != nil {
				if debug {
					log.Printf("discarding fact %s about %s\n", fact, k.obj)
				}
				continue // object not accessible from package API; discard fact
			}
			object = path
		}
		gobFacts = append(gobFacts, gobFact{
			PkgPath: k.pkg.Path(),
			Object:  object,
			Fact:    fact,
		})
	}
	s.mu.Unlock()

	// Sort facts by (package, object, type) for determinism.
	sort.Slice(gobFacts, func(i, j int) bool {
		x, y := gobFacts[i], gobFacts[j]
		if x.PkgPath != y.PkgPath {
			return x.PkgPath < y.PkgPath
		}
		if x.Object != y.Object {
			return x.Object < y.Object
		}
		tx := reflect.TypeOf(x.Fact)
		ty := reflect.TypeOf(y.Fact)
		if tx != ty {
			return tx.String() < ty.String()
		}
		return false // equal
	})

	var buf bytes.Buffer
	if len(gobFacts) > 0 {
		if err := gob.NewEncoder(&buf).Encode(gobFacts); err != nil {
			// Fact encoding should never fail. Identify the culprit.
			for _, gf := range gobFacts {
				if err := gob.NewEncoder(io.Discard).Encode(gf); err != nil {
					fact := gf.Fact
					pkgpath := reflect.TypeOf(fact).Elem().PkgPath()
					log.Panicf("internal error: gob encoding of analysis fact %s failed: %v; please report a bug against fact %T in package %q",
						fact, err, fact, pkgpath)
				}
			}
		}
	}

	if debug {
		log.Printf("package %q: encode %d facts, %d bytes\n",
			s.pkg.Path(), len(gobFacts), buf.Len())
	}

	return buf.Bytes()
}

// String is provided only for debugging, and must not be called
// concurrent with any Import/Export method.
func (s *Set) String() string {
	var buf bytes.Buffer
	buf.WriteString("{")
	for k, f := range s.m {
		if buf.Len() > 1 {
			buf.WriteString(", ")
		}
		if k.obj != nil {
			buf.WriteString(k.obj.String())
		} else {
			buf.WriteString(k.pkg.Path())
		}
		fmt.Fprintf(&buf, ": %v", f)
	}
	buf.WriteString("}")
	return buf.String()
}


================================================
FILE: internal/facts/facts_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package facts_test

import (
	"encoding/gob"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/go/packages"

	"golang.org/x/tools/internal/facts"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/typesinternal"
)

type myFact struct {
	S string
}

func (f *myFact) String() string { return fmt.Sprintf("myFact(%s)", f.S) }
func (f *myFact) AFact()         {}

func init() {
	gob.Register(new(myFact))
}

func TestEncodeDecode(t *testing.T) {
	tests := []struct {
		name     string
		files    map[string]string
		plookups []pkgLookups // see testEncodeDecode for details
	}{
		{
			name: "loading-order",
			// c -> b -> a, a2
			// c does not directly depend on a, but it indirectly uses a.T.
			//
			// Package a2 is never loaded directly so it is incomplete.
			//
			// We use only types in this example because we rely on
			// types.Eval to resolve the lookup expressions, and it only
			// works for types. This is a definite gap in the typechecker API.
			files: map[string]string{
				"a/a.go":  `package a; type A int; type T int`,
				"a2/a.go": `package a2; type A2 int; type Unneeded int`,
				"b/b.go":  `package b; import ("a"; "a2"); type B chan a2.A2; type F func() a.T`,
				"c/c.go":  `package c; import "b"; type C []b.B`,
			},
			// In the following table, we analyze packages (a, b, c) in order,
			// look up various objects accessible within each package,
			// and see if they have a fact.  The "analysis" exports a fact
			// for every object at package level.
			//
			// Note: Loop iterations are not independent test cases;
			// order matters, as we populate factmap.
			plookups: []pkgLookups{
				{"a", []lookup{
					{"A", "myFact(a.A)"},
				}},
				{"b", []lookup{
					{"a.A", "myFact(a.A)"},
					{"a.T", "myFact(a.T)"},
					{"B", "myFact(b.B)"},
					{"F", "myFact(b.F)"},
					{"F(nil)()", "myFact(a.T)"}, // (result type of b.F)
				}},
				{"c", []lookup{
					{"b.B", "myFact(b.B)"},
					{"b.F", "myFact(b.F)"},
					{"b.F(nil)()", "myFact(a.T)"},
					{"C", "myFact(c.C)"},
					{"C{}[0]", "myFact(b.B)"},
					{"<-(C{}[0])", "no fact"}, // object but no fact (we never "analyze" a2)
				}},
			},
		},
		{
			name: "underlying",
			// c->b->a
			// c does not import a directly or use any of its types, but it does use
			// the types within a indirectly. c.q has the type a.a so package a should
			// be included by importMap.
			files: map[string]string{
				"a/a.go": `package a; type a int; type T *a`,
				"b/b.go": `package b; import "a"; type B a.T`,
				"c/c.go": `package c; import "b"; type C b.B; var q = *C(nil)`,
			},
			plookups: []pkgLookups{
				{"a", []lookup{
					{"a", "myFact(a.a)"},
					{"T", "myFact(a.T)"},
				}},
				{"b", []lookup{
					{"B", "myFact(b.B)"},
					{"B(nil)", "myFact(b.B)"},
					{"*(B(nil))", "myFact(a.a)"},
				}},
				{"c", []lookup{
					{"C", "myFact(c.C)"},
					{"C(nil)", "myFact(c.C)"},
					{"*C(nil)", "myFact(a.a)"},
					{"q", "myFact(a.a)"},
				}},
			},
		},
		{
			name: "methods",
			// c->b->a
			// c does not import a directly or use any of its types, but it does use
			// the types within a indirectly via a method.
			files: map[string]string{
				"a/a.go": `package a; type T int`,
				"b/b.go": `package b; import "a"; type B struct{}; func (_ B) M() a.T { return 0 }`,
				"c/c.go": `package c; import "b"; var C b.B`,
			},
			plookups: []pkgLookups{
				{"a", []lookup{
					{"T", "myFact(a.T)"},
				}},
				{"b", []lookup{
					{"B{}", "myFact(b.B)"},
					{"B{}.M()", "myFact(a.T)"},
				}},
				{"c", []lookup{
					{"C", "myFact(b.B)"},
					{"C.M()", "myFact(a.T)"},
				}},
			},
		},
		{
			name: "globals",
			files: map[string]string{
				"a/a.go": `package a;
				type T1 int
				type T2 int
				type T3 int
				type T4 int
				type T5 int
				type K int; type V string
				`,
				"b/b.go": `package b
				import "a"
				var (
					G1 []a.T1
					G2 [7]a.T2
					G3 chan a.T3
					G4 *a.T4
					G5 struct{ F a.T5 }
					G6 map[a.K]a.V
				)
				`,
				"c/c.go": `package c; import "b";
				var (
					v1 = b.G1
					v2 = b.G2
					v3 = b.G3
					v4 = b.G4
					v5 = b.G5
					v6 = b.G6
				)
				`,
			},
			plookups: []pkgLookups{
				{"a", []lookup{}},
				{"b", []lookup{}},
				{"c", []lookup{
					{"v1[0]", "myFact(a.T1)"},
					{"v2[0]", "myFact(a.T2)"},
					{"<-v3", "myFact(a.T3)"},
					{"*v4", "myFact(a.T4)"},
					{"v5.F", "myFact(a.T5)"},
					{"v6[0]", "myFact(a.V)"},
				}},
			},
		},
		{
			name: "typeparams",
			files: map[string]string{
				"a/a.go": `package a
				  type T1 int
				  type T2 int
				  type T3 interface{Foo()}
				  type T4 int
				  type T5 int
				  type T6 interface{Foo()}
				`,
				"b/b.go": `package b
				  import "a"
				  type N1[T a.T1|int8] func() T
				  type N2[T any] struct{ F T }
				  type N3[T a.T3] func() T
				  type N4[T a.T4|int8] func() T
				  type N5[T interface{Bar() a.T5} ] func() T

				  type t5 struct{}; func (t5) Bar() a.T5 { return 0 }

				  var G1 N1[a.T1]
				  var G2 func() N2[a.T2]
				  var G3 N3[a.T3]
				  var G4 N4[a.T4]
				  var G5 N5[t5]

				  func F6[T a.T6]() T { var x T; return x }
				  `,
				"c/c.go": `package c; import "b";
				  var (
					  v1 = b.G1
					  v2 = b.G2
					  v3 = b.G3
					  v4 = b.G4
					  v5 = b.G5
					  v6 = b.F6[t6]
				  )

				  type t6 struct{}; func (t6) Foo() {}
				`,
			},
			plookups: []pkgLookups{
				{"a", []lookup{}},
				{"b", []lookup{}},
				{"c", []lookup{
					{"v1", "myFact(b.N1)"},
					{"v1()", "myFact(a.T1)"},
					{"v2()", "myFact(b.N2)"},
					{"v2().F", "myFact(a.T2)"},
					{"v3", "myFact(b.N3)"},
					{"v4", "myFact(b.N4)"},
					{"v4()", "myFact(a.T4)"},
					{"v5", "myFact(b.N5)"},
					{"v5()", "myFact(b.t5)"},
					{"v6()", "myFact(c.t6)"},
				}},
			},
		},
	}
	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()
			testEncodeDecode(t, test.files, test.plookups)
		})
	}
}

func TestEncodeDecodeAliases(t *testing.T) {
	testenv.NeedsGo1Point(t, 24)

	files := map[string]string{
		"a/a.go": `package a
				  type A = int
				`,
		"b/b.go": `package b
				  import "a"
				  type B = a.A
				`,
		"c/c.go": `package c
				  import "b";
				  type N1[T int|~string] = struct{}

				  var V1 = N1[b.B]{}
				`,
	}
	plookups := []pkgLookups{
		{"a", []lookup{}},
		{"b", []lookup{}},
		// fake objexpr for RHS of V1's type arg (see customFind hack)
		{"c", []lookup{{"c.V1->c.N1->b.B->a.A", "myFact(a.A)"}}},
	}
	testEncodeDecode(t, files, plookups)
}

type lookup struct {
	objexpr string // expression whose type is a named type
	want    string // printed form of fact associated with that type (or "no fact")
}

type pkgLookups struct {
	path    string
	lookups []lookup
}

// testEncodeDecode tests fact encoding and decoding and simulates how package facts
// are passed during analysis. It operates on a group of Go file contents. Then
// for each <package, []lookup> in tests it does the following:
//  1. loads and type checks the package,
//  2. calls (*facts.Decoder).Decode to load the facts exported by its imports,
//  3. exports a myFact Fact for all of package level objects,
//  4. For each lookup for the current package:
//     4.a) lookup the types.Object for a Go source expression in the current package
//     (or confirms one is not expected want=="no object"),
//     4.b) finds a Fact for the object (or confirms one is not expected want=="no fact"),
//     4.c) compares the content of the Fact to want.
//  5. encodes the Facts of the package.
//
// Note: tests are not independent test cases; order matters (as does a package being
// skipped). It changes what Facts can be imported.
//
// Failures are reported on t.
func testEncodeDecode(t *testing.T, files map[string]string, tests []pkgLookups) {
	dir, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()

	// factmap represents the passing of encoded facts from one
	// package to another. In practice one would use the file system.
	factmap := make(map[string][]byte)
	read := func(pkgPath string) ([]byte, error) { return factmap[pkgPath], nil }

	// Analyze packages in order, look up various objects accessible within
	// each package, and see if they have a fact.  The "analysis" exports a
	// fact for every object at package level.
	//
	// Note: Loop iterations are not independent test cases;
	// order matters, as we populate factmap.
	for _, test := range tests {
		// load package
		pkg, err := load(t, dir, test.path)
		if err != nil {
			t.Fatal(err)
		}

		// decode
		facts, err := facts.NewDecoder(pkg).Decode(read)
		if err != nil {
			t.Fatalf("Decode failed: %v", err)
		}
		t.Logf("decode %s facts = %v", pkg.Path(), facts) // show all facts

		// export
		// (one fact for each package-level object)
		for _, name := range pkg.Scope().Names() {
			obj := pkg.Scope().Lookup(name)
			fact := &myFact{obj.Pkg().Name() + "." + obj.Name()}
			facts.ExportObjectFact(obj, fact)
		}
		t.Logf("exported %s facts = %v", pkg.Path(), facts) // show all facts

		// import
		// (after export, because an analyzer may import its own facts)
		for _, lookup := range test.lookups {
			fact := new(myFact)
			var got string
			if obj := find(pkg, lookup.objexpr); obj == nil {
				got = "no object"
			} else if facts.ImportObjectFact(obj, fact) {
				got = fact.String()
			} else {
				got = "no fact"
			}
			if got != lookup.want {
				t.Errorf("in %s, ImportObjectFact(%s, %T) = %s, want %s",
					pkg.Path(), lookup.objexpr, fact, got, lookup.want)
			}
		}

		// encode
		factmap[pkg.Path()] = facts.Encode()
	}
}

// customFind allows for overriding how an object is looked up
// by find. This is necessary for objects that are accessible through
// the API but are not the type of any expression we can pass to types.CheckExpr.
var customFind = map[string]func(p *types.Package) types.Object{
	"c.V1->c.N1->b.B->a.A": func(p *types.Package) types.Object {
		cV1 := p.Scope().Lookup("V1")
		cN1 := cV1.Type().(*types.Alias)
		aT1 := cN1.TypeArgs().At(0).(*types.Alias)
		zZ1 := aT1.Rhs().(*types.Alias)
		return zZ1.Obj()
	},
}

func find(p *types.Package, expr string) types.Object {
	// types.Eval only allows us to compute a TypeName object for an expression.
	// TODO(adonovan): support other expressions that denote an object:
	// - an identifier (or qualified ident) for a func, const, or var
	// - new(T).f for a field or method
	// I've added CheckExpr in https://go-review.googlesource.com/c/go/+/144677.
	// If that becomes available, use it.
	if f := customFind[expr]; f != nil {
		return f(p)
	}
	// Choose an arbitrary position within the (single-file) package
	// so that we are within the scope of its import declarations.
	somepos := p.Scope().Lookup(p.Scope().Names()[0]).Pos()
	tv, err := types.Eval(token.NewFileSet(), p, somepos, expr)
	if err != nil {
		return nil
	}
	if n, ok := tv.Type.(typesinternal.NamedOrAlias); ok {
		return n.Obj()
	}
	return nil
}

func load(t *testing.T, dir string, path string) (*types.Package, error) {
	cfg := &packages.Config{
		Mode: packages.LoadSyntax,
		Dir:  dir,
		Env:  append(os.Environ(), "GOPATH="+dir, "GO111MODULE=off", "GOPROXY=off"),
	}
	testenv.NeedsGoPackagesEnv(t, cfg.Env)
	pkgs, err := packages.Load(cfg, path)
	if err != nil {
		return nil, err
	}
	if packages.PrintErrors(pkgs) > 0 {
		return nil, fmt.Errorf("packages had errors")
	}
	if len(pkgs) == 0 {
		return nil, fmt.Errorf("no package matched %s", path)
	}
	return pkgs[0].Types, nil
}

type otherFact struct {
	S string
}

func (f *otherFact) String() string { return fmt.Sprintf("otherFact(%s)", f.S) }
func (f *otherFact) AFact()         {}

func TestFactFilter(t *testing.T) {
	files := map[string]string{
		"a/a.go": `package a; type A int`,
	}
	dir, cleanup, err := analysistest.WriteFiles(files)
	if err != nil {
		t.Fatal(err)
	}
	defer cleanup()

	pkg, err := load(t, dir, "a")
	if err != nil {
		t.Fatal(err)
	}

	obj := pkg.Scope().Lookup("A")
	s, err := facts.NewDecoder(pkg).Decode(func(pkgPath string) ([]byte, error) { return nil, nil })
	if err != nil {
		t.Fatal(err)
	}
	s.ExportObjectFact(obj, &myFact{"good object fact"})
	s.ExportPackageFact(&myFact{"good package fact"})
	s.ExportObjectFact(obj, &otherFact{"bad object fact"})
	s.ExportPackageFact(&otherFact{"bad package fact"})

	filter := map[reflect.Type]bool{
		reflect.TypeFor[*myFact](): true,
	}

	pkgFacts := s.AllPackageFacts(filter)
	wantPkgFacts := `[{package a ("a") myFact(good package fact)}]`
	if got := fmt.Sprintf("%v", pkgFacts); got != wantPkgFacts {
		t.Errorf("AllPackageFacts: got %v, want %v", got, wantPkgFacts)
	}

	objFacts := s.AllObjectFacts(filter)
	wantObjFacts := "[{type a.A int myFact(good object fact)}]"
	if got := fmt.Sprintf("%v", objFacts); got != wantObjFacts {
		t.Errorf("AllObjectFacts: got %v, want %v", got, wantObjFacts)
	}
}

// TestMalformed checks that facts can be encoded and decoded *despite*
// types.Config.Check returning an error. Importing facts is expected to
// happen when Analyzers have RunDespiteErrors set to true. So this
// needs to robust, e.g. no infinite loops.
func TestMalformed(t *testing.T) {
	var findPkg func(*types.Package, string) *types.Package
	findPkg = func(p *types.Package, name string) *types.Package {
		if p.Name() == name {
			return p
		}
		for _, o := range p.Imports() {
			if f := findPkg(o, name); f != nil {
				return f
			}
		}
		return nil
	}

	type pkgTest struct {
		content string
		err     string            // if non-empty, expected substring of err.Error() from conf.Check().
		wants   map[string]string // package path to expected name
	}
	tests := []struct {
		name string
		pkgs []pkgTest
	}{
		{
			name: "initialization-cycle",
			pkgs: []pkgTest{
				// Notation: myFact(a.[N]) means: package a has members {N}.
				{
					content: `package a; type N[T any] struct { F *N[N[T]] }`,
					err:     "instantiation cycle:",
					wants:   map[string]string{"a": "myFact(a.[N])", "b": "no package", "c": "no package"},
				},
				{
					content: `package b; import "a"; type B a.N[int]`,
					wants:   map[string]string{"a": "myFact(a.[N])", "b": "myFact(b.[B])", "c": "no package"},
				},
				{
					content: `package c; import "b"; var C b.B`,
					wants:   map[string]string{"a": "no fact", "b": "myFact(b.[B])", "c": "myFact(c.[C])"},
					// package fact myFact(a.[N]) not reexported
				},
			},
		},
	}

	for i := range tests {
		test := tests[i]
		t.Run(test.name, func(t *testing.T) {
			t.Parallel()

			// setup for test wide variables.
			packages := make(map[string]*types.Package)
			conf := types.Config{
				Importer: closure(packages),
				Error:    func(err error) {}, // do not stop on first type checking error
			}
			fset := token.NewFileSet()
			factmap := make(map[string][]byte)
			read := func(pkgPath string) ([]byte, error) { return factmap[pkgPath], nil }

			// Processes the pkgs in order. For package, export a package fact,
			// and use this fact to verify which package facts are reachable via Decode.
			// We allow for packages to have type checking errors.
			for i, pkgTest := range test.pkgs {
				// parse
				f, err := parser.ParseFile(fset, fmt.Sprintf("%d.go", i), pkgTest.content, 0)
				if err != nil {
					t.Fatal(err)
				}

				// typecheck
				pkg, err := conf.Check(f.Name.Name, fset, []*ast.File{f}, nil)
				var got string
				if err != nil {
					got = err.Error()
				}
				if !strings.Contains(got, pkgTest.err) {
					t.Fatalf("%s: type checking error %q did not match pattern %q", pkg.Path(), err.Error(), pkgTest.err)
				}
				packages[pkg.Path()] = pkg

				// decode facts
				facts, err := facts.NewDecoder(pkg).Decode(read)
				if err != nil {
					t.Fatalf("Decode failed: %v", err)
				}

				// export facts
				fact := &myFact{fmt.Sprintf("%s.%s", pkg.Name(), pkg.Scope().Names())}
				facts.ExportPackageFact(fact)

				// import facts
				for other, want := range pkgTest.wants {
					fact := new(myFact)
					var got string
					if found := findPkg(pkg, other); found == nil {
						got = "no package"
					} else if facts.ImportPackageFact(found, fact) {
						got = fact.String()
					} else {
						got = "no fact"
					}
					if got != want {
						t.Errorf("in %s, ImportPackageFact(%s, %T) = %s, want %s",
							pkg.Path(), other, fact, got, want)
					}
				}

				// encode facts
				factmap[pkg.Path()] = facts.Encode()
			}
		})
	}
}

type closure map[string]*types.Package

func (c closure) Import(path string) (*types.Package, error) { return c[path], nil }


================================================
FILE: internal/facts/imports.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package facts

import (
	"go/types"

	"golang.org/x/tools/internal/typesinternal"
)

// importMap computes the import map for a package by traversing the
// entire exported API each of its imports.
//
// This is a workaround for the fact that we cannot access the map used
// internally by the types.Importer returned by go/importer. The entries
// in this map are the packages and objects that may be relevant to the
// current analysis unit.
//
// Packages in the map that are only indirectly imported may be
// incomplete (!pkg.Complete()).
//
// This function scales very poorly with packages' transitive object
// references, which can be more than a million for each package near
// the top of a large project. (This was a significant contributor to
// #60621.)
// TODO(adonovan): opt: compute this information more efficiently
// by obtaining it from the internals of the gcexportdata decoder.
func importMap(imports []*types.Package) map[string]*types.Package {
	objects := make(map[types.Object]bool)
	typs := make(map[types.Type]bool) // Named and TypeParam
	packages := make(map[string]*types.Package)

	var addObj func(obj types.Object)
	var addType func(T types.Type)

	addObj = func(obj types.Object) {
		if !objects[obj] {
			objects[obj] = true
			addType(obj.Type())
			if pkg := obj.Pkg(); pkg != nil {
				packages[pkg.Path()] = pkg
			}
		}
	}

	addType = func(T types.Type) {
		switch T := T.(type) {
		case *types.Basic:
			// nop
		case typesinternal.NamedOrAlias: // *types.{Named,Alias}
			// Add the type arguments if this is an instance.
			if targs := T.TypeArgs(); targs.Len() > 0 {
				for t := range targs.Types() {
					addType(t)
				}
			}

			// Remove infinite expansions of *types.Named by always looking at the origin.
			// Some named types with type parameters [that will not type check] have
			// infinite expansions:
			//     type N[T any] struct { F *N[N[T]] }
			// importMap() is called on such types when Analyzer.RunDespiteErrors is true.
			T = typesinternal.Origin(T)
			if !typs[T] {
				typs[T] = true

				// common aspects
				addObj(T.Obj())
				if tparams := T.TypeParams(); tparams.Len() > 0 {
					for tparam := range tparams.TypeParams() {
						addType(tparam)
					}
				}

				// variant aspects
				switch T := T.(type) {
				case *types.Alias:
					addType(T.Rhs())
				case *types.Named:
					addType(T.Underlying())
					for method := range T.Methods() {
						addObj(method)
					}
				}
			}
		case *types.Pointer:
			addType(T.Elem())
		case *types.Slice:
			addType(T.Elem())
		case *types.Array:
			addType(T.Elem())
		case *types.Chan:
			addType(T.Elem())
		case *types.Map:
			addType(T.Key())
			addType(T.Elem())
		case *types.Signature:
			addType(T.Params())
			addType(T.Results())
			if tparams := T.TypeParams(); tparams != nil {
				for tparam := range tparams.TypeParams() {
					addType(tparam)
				}
			}
		case *types.Struct:
			for field := range T.Fields() {
				addObj(field)
			}
		case *types.Tuple:
			for v := range T.Variables() {
				addObj(v)
			}
		case *types.Interface:
			for method := range T.Methods() {
				addObj(method)
			}
			for etyp := range T.EmbeddedTypes() {
				addType(etyp) // walk Embedded for implicits
			}
		case *types.Union:
			for term := range T.Terms() {
				addType(term.Type())
			}
		case *types.TypeParam:
			if !typs[T] {
				typs[T] = true
				addObj(T.Obj())
				addType(T.Constraint())
			}
		}
	}

	for _, imp := range imports {
		packages[imp.Path()] = imp

		scope := imp.Scope()
		for _, name := range scope.Names() {
			addObj(scope.Lookup(name))
		}
	}

	return packages
}


================================================
FILE: internal/fmtstr/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The fmtstr command parses the format strings of calls to selected
// printf-like functions in the specified source file, and prints the
// formatting operations and their operands.
//
// It is intended only for debugging and is not a supported interface.
package main

import (
	"flag"
	"fmt"
	"go/ast"
	"go/parser"
	"go/printer"
	"go/token"
	"log"
	"strconv"
	"strings"

	"golang.org/x/tools/internal/fmtstr"
)

func main() {
	log.SetPrefix("fmtstr: ")
	log.SetFlags(0)
	flag.Parse()

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, flag.Args()[0], nil, 0)
	if err != nil {
		log.Fatal(err)
	}

	functions := map[string]int{
		"fmt.Errorf":  0,
		"fmt.Fprintf": 1,
		"fmt.Printf":  0,
		"fmt.Sprintf": 0,
		"log.Printf":  0,
	}

	ast.Inspect(f, func(n ast.Node) bool {
		if call, ok := n.(*ast.CallExpr); ok && !call.Ellipsis.IsValid() {
			if sel, ok := call.Fun.(*ast.SelectorExpr); ok && is[*ast.Ident](sel.X) {
				name := sel.X.(*ast.Ident).Name + "." + sel.Sel.Name // e.g. "fmt.Printf"
				if fmtstrIndex, ok := functions[name]; ok &&
					len(call.Args) > fmtstrIndex {
					// Is it a string literal?
					if fmtstrArg, ok := call.Args[fmtstrIndex].(*ast.BasicLit); ok &&
						fmtstrArg.Kind == token.STRING {
						// Have fmt.Printf("format", ...)
						format, _ := strconv.Unquote(fmtstrArg.Value)

						ops, err := fmtstr.Parse(format, 0)
						if err != nil {
							log.Printf("%s: %v", fset.Position(fmtstrArg.Pos()), err)
							return true
						}

						fmt.Printf("%s: %s(%s, ...)\n",
							fset.Position(fmtstrArg.Pos()),
							name,
							fmtstrArg.Value)
						for _, op := range ops {
							// TODO(adonovan): show more detail.
							fmt.Printf("\t%q\t%v\n",
								op.Text,
								formatNode(fset, call.Args[op.Verb.ArgIndex]))
						}
					}
				}
			}
		}
		return true
	})
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

func formatNode(fset *token.FileSet, n ast.Node) string {
	var buf strings.Builder
	if err := printer.Fprint(&buf, fset, n); err != nil {
		return "<error>"
	}
	return buf.String()
}


================================================
FILE: internal/fmtstr/parse.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package fmtstr defines a parser for format strings as used by [fmt.Printf].
package fmtstr

import (
	"fmt"
	"strconv"
	"strings"
	"unicode/utf8"
)

// Operation holds the parsed representation of a printf operation such as "%3.*[4]d".
// It is constructed by [Parse].
type Operation struct {
	Text  string // full text of the operation, e.g. "%[2]*.3d"
	Verb  Verb   // verb specifier, guaranteed to exist, e.g., 'd' in '%[1]d'
	Range Range  // the range of Text within the overall format string
	Flags string // formatting flags, e.g. "-0"
	Width Size   // width specifier, e.g., '3' in '%3d'
	Prec  Size   // precision specifier, e.g., '.4' in '%.4f'
}

// Size describes an optional width or precision in a format operation.
// It may represent no value, a literal number, an asterisk, or an indexed asterisk.
type Size struct {
	// At most one of these two fields is non-negative.
	Fixed   int // e.g. 4 from "%4d", otherwise -1
	Dynamic int // index of argument providing dynamic size (e.g. %*d or %[3]*d), otherwise -1

	Index int   // If the width or precision uses an indexed argument (e.g. 2 in %[2]*d), this is the index, otherwise -1
	Range Range // position of the size specifier within the operation
}

// Verb represents the verb character of a format operation (e.g., 'd', 's', 'f').
// It also includes positional information and any explicit argument indexing.
type Verb struct {
	Verb     rune
	Range    Range // positional range of the verb in the format string
	Index    int   // index of an indexed argument, (e.g. 2 in %[2]d), otherwise -1
	ArgIndex int   // argument index (0-based) associated with this verb, relative to CallExpr
}

// byte offsets of format string
type Range struct {
	Start, End int
}

// Parse takes a format string and its index in the printf-like call,
// parses out all format operations, returns a slice of parsed
// [Operation] which describes flags, width, precision, verb, and argument indexing,
// or an error if parsing fails.
//
// All error messages are in predicate form ("call has a problem")
// so that they may be affixed into a subject ("log.Printf ").
//
// The flags will only be a subset of ['#', '0', '+', '-', ' '].
// It does not perform any validation of verbs, nor the
// existence of corresponding arguments (obviously it can't). The provided format string may differ
// from the one in CallExpr, such as a concatenated string or a string
// referred to by the argument in the CallExpr.
func Parse(format string, idx int) ([]*Operation, error) {
	if !strings.Contains(format, "%") {
		return nil, fmt.Errorf("call has arguments but no formatting directives")
	}

	firstArg := idx + 1 // Arguments are immediately after format string.
	argNum := firstArg
	var operations []*Operation
	for i, w := 0, 0; i < len(format); i += w {
		w = 1
		if format[i] != '%' {
			continue
		}
		state, err := parseOperation(format[i:], firstArg, argNum)
		if err != nil {
			return nil, err
		}

		state.operation.addOffset(i)
		operations = append(operations, state.operation)

		w = len(state.operation.Text)
		// Do not waste an argument for '%'.
		if state.operation.Verb.Verb != '%' {
			argNum = state.argNum + 1
		}
	}
	return operations, nil
}

// Internal parsing state to operation.
type state struct {
	operation    *Operation
	firstArg     int  // index of the first argument after the format string
	argNum       int  // which argument we're expecting to format now
	hasIndex     bool // whether the argument is indexed
	index        int  // the encountered index
	indexPos     int  // the encountered index's offset
	indexPending bool // whether we have an indexed argument that has not resolved
	nbytes       int  // number of bytes of the format string consumed
}

// parseOperation parses one format operation starting at the given substring `format`,
// which should begin with '%'. It returns a fully populated state or an error
// if the operation is malformed. The firstArg and argNum parameters help determine how
// arguments map to this operation.
//
// Parse sequence: '%' -> flags -> {[N]* or width} -> .{[N]* or precision} -> [N] -> verb.
func parseOperation(format string, firstArg, argNum int) (*state, error) {
	state := &state{
		operation: &Operation{
			Text: format,
			Width: Size{
				Fixed:   -1,
				Dynamic: -1,
				Index:   -1,
			},
			Prec: Size{
				Fixed:   -1,
				Dynamic: -1,
				Index:   -1,
			},
		},
		firstArg:     firstArg,
		argNum:       argNum,
		hasIndex:     false,
		index:        0,
		indexPos:     0,
		indexPending: false,
		nbytes:       len("%"), // There's guaranteed to be a percent sign.
	}
	// There may be flags.
	state.parseFlags()
	// There may be an index.
	if err := state.parseIndex(); err != nil {
		return nil, err
	}
	// There may be a width.
	state.parseSize(Width)
	// There may be a precision.
	if err := state.parsePrecision(); err != nil {
		return nil, err
	}
	// Now a verb, possibly prefixed by an index (which we may already have).
	if !state.indexPending {
		if err := state.parseIndex(); err != nil {
			return nil, err
		}
	}
	if state.nbytes == len(state.operation.Text) {
		return nil, fmt.Errorf("format %s is missing verb at end of string", state.operation.Text)
	}
	verb, w := utf8.DecodeRuneInString(state.operation.Text[state.nbytes:])

	// Ensure there must be a verb.
	if state.indexPending {
		state.operation.Verb = Verb{
			Verb: verb,
			Range: Range{
				Start: state.indexPos,
				End:   state.nbytes + w,
			},
			Index:    state.index,
			ArgIndex: state.argNum,
		}
	} else {
		state.operation.Verb = Verb{
			Verb: verb,
			Range: Range{
				Start: state.nbytes,
				End:   state.nbytes + w,
			},
			Index:    -1,
			ArgIndex: state.argNum,
		}
	}

	state.nbytes += w
	state.operation.Text = state.operation.Text[:state.nbytes]
	return state, nil
}

// addOffset adjusts the recorded positions in Verb, Width, Prec, and the
// operation's overall Range to be relative to the position in the full format string.
func (s *Operation) addOffset(parsedLen int) {
	s.Verb.Range.Start += parsedLen
	s.Verb.Range.End += parsedLen

	s.Range.Start = parsedLen
	s.Range.End = s.Verb.Range.End

	// one of Fixed or Dynamic is non-negative means existence.
	if s.Prec.Fixed != -1 || s.Prec.Dynamic != -1 {
		s.Prec.Range.Start += parsedLen
		s.Prec.Range.End += parsedLen
	}
	if s.Width.Fixed != -1 || s.Width.Dynamic != -1 {
		s.Width.Range.Start += parsedLen
		s.Width.Range.End += parsedLen
	}
}

// parseFlags accepts any printf flags.
func (s *state) parseFlags() {
	s.operation.Flags = prefixOf(s.operation.Text[s.nbytes:], "#0+- ")
	s.nbytes += len(s.operation.Flags)
}

// prefixOf returns the prefix of s composed only of runes from the specified set.
func prefixOf(s, set string) string {
	rest := strings.TrimLeft(s, set)
	return s[:len(s)-len(rest)]
}

// parseIndex parses an argument index of the form "[n]" that can appear
// in a printf operation (e.g., "%[2]d"). Returns an error if syntax is
// malformed or index is invalid.
func (s *state) parseIndex() error {
	if s.nbytes == len(s.operation.Text) || s.operation.Text[s.nbytes] != '[' {
		return nil
	}
	// Argument index present.
	s.nbytes++ // skip '['
	start := s.nbytes
	if num, ok := s.scanNum(); ok {
		// Later consumed/stored by a '*' or verb.
		s.index = num
		s.indexPos = start - 1
	}

	ok := true
	if s.nbytes == len(s.operation.Text) || s.nbytes == start || s.operation.Text[s.nbytes] != ']' {
		ok = false // syntax error is either missing "]" or invalid index.
		s.nbytes = strings.Index(s.operation.Text[start:], "]")
		if s.nbytes < 0 {
			return fmt.Errorf("format %s is missing closing ]", s.operation.Text)
		}
		s.nbytes = s.nbytes + start
	}
	arg32, err := strconv.ParseInt(s.operation.Text[start:s.nbytes], 10, 32)
	if err != nil || !ok || arg32 <= 0 {
		return fmt.Errorf("format has invalid argument index [%s]", s.operation.Text[start:s.nbytes])
	}

	s.nbytes++ // skip ']'
	arg := int(arg32)
	arg += s.firstArg - 1 // We want to zero-index the actual arguments.
	s.argNum = arg
	s.hasIndex = true
	s.indexPending = true
	return nil
}

// scanNum advances through a decimal number if present, which represents a [Size] or [Index].
func (s *state) scanNum() (int, bool) {
	start := s.nbytes
	for ; s.nbytes < len(s.operation.Text); s.nbytes++ {
		c := s.operation.Text[s.nbytes]
		if c < '0' || '9' < c {
			if start < s.nbytes {
				num, _ := strconv.ParseInt(s.operation.Text[start:s.nbytes], 10, 32)
				return int(num), true
			} else {
				return 0, false
			}
		}
	}
	return 0, false
}

type sizeType int

const (
	Width sizeType = iota
	Precision
)

// parseSize parses a width or precision specifier. It handles literal numeric
// values (e.g., "%3d"), asterisk values (e.g., "%*d"), or indexed asterisk values (e.g., "%[2]*d").
func (s *state) parseSize(kind sizeType) {
	if s.nbytes < len(s.operation.Text) && s.operation.Text[s.nbytes] == '*' {
		s.nbytes++
		if s.indexPending {
			// Absorb it.
			s.indexPending = false
			size := Size{
				Fixed:   -1,
				Dynamic: s.argNum,
				Index:   s.index,
				Range: Range{
					Start: s.indexPos,
					End:   s.nbytes,
				},
			}
			switch kind {
			case Width:
				s.operation.Width = size
			case Precision:
				// Include the leading '.'.
				size.Range.Start -= len(".")
				s.operation.Prec = size
			default:
				panic(kind)
			}
		} else {
			// Non-indexed asterisk: "%*d".
			size := Size{
				Dynamic: s.argNum,
				Index:   -1,
				Fixed:   -1,
				Range: Range{
					Start: s.nbytes - 1,
					End:   s.nbytes,
				},
			}
			switch kind {
			case Width:
				s.operation.Width = size
			case Precision:
				// For precision, include the '.' in the range.
				size.Range.Start -= 1
				s.operation.Prec = size
			default:
				panic(kind)
			}
		}
		s.argNum++
	} else { // Literal number, e.g. "%10d"
		start := s.nbytes
		if num, ok := s.scanNum(); ok {
			size := Size{
				Fixed:   num,
				Index:   -1,
				Dynamic: -1,
				Range: Range{
					Start: start,
					End:   s.nbytes,
				},
			}
			switch kind {
			case Width:
				s.operation.Width = size
			case Precision:
				// Include the leading '.'.
				size.Range.Start -= 1
				s.operation.Prec = size
			default:
				panic(kind)
			}
		}
	}
}

// parsePrecision checks if there's a precision specified after a '.' character.
// If found, it may also parse an index or an asterisk. Returns an error if any index
// parsing fails.
func (s *state) parsePrecision() error {
	// If there's a period, there may be a precision.
	if s.nbytes < len(s.operation.Text) && s.operation.Text[s.nbytes] == '.' {
		s.nbytes++
		if err := s.parseIndex(); err != nil {
			return err
		}
		s.parseSize(Precision)
	}
	return nil
}


================================================
FILE: internal/gcimporter/bexport_test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/internal/gcimporter"
)

var isRace = false

func fileLine(fset *token.FileSet, obj types.Object) string {
	posn := fset.Position(obj.Pos())
	filename := filepath.Clean(strings.ReplaceAll(posn.Filename, "$GOROOT", runtime.GOROOT()))
	return fmt.Sprintf("%s:%d", filename, posn.Line)
}

func equalType(x, y types.Type) error {
	x = types.Unalias(x)
	y = types.Unalias(y)
	if reflect.TypeOf(x) != reflect.TypeOf(y) {
		return fmt.Errorf("unequal kinds: %T vs %T", x, y)
	}
	switch x := x.(type) {
	case *types.Interface:
		y := y.(*types.Interface)
		// TODO(gri): enable separate emission of Embedded interfaces
		// and ExplicitMethods then use this logic.
		// if x.NumEmbeddeds() != y.NumEmbeddeds() {
		// 	return fmt.Errorf("unequal number of embedded interfaces: %d vs %d",
		// 		x.NumEmbeddeds(), y.NumEmbeddeds())
		// }
		// for i := 0; i < x.NumEmbeddeds(); i++ {
		// 	xi := x.Embedded(i)
		// 	yi := y.Embedded(i)
		// 	if xi.String() != yi.String() {
		// 		return fmt.Errorf("mismatched %th embedded interface: %s vs %s",
		// 			i, xi, yi)
		// 	}
		// }
		// if x.NumExplicitMethods() != y.NumExplicitMethods() {
		// 	return fmt.Errorf("unequal methods: %d vs %d",
		// 		x.NumExplicitMethods(), y.NumExplicitMethods())
		// }
		// for i := 0; i < x.NumExplicitMethods(); i++ {
		// 	xm := x.ExplicitMethod(i)
		// 	ym := y.ExplicitMethod(i)
		// 	if xm.Name() != ym.Name() {
		// 		return fmt.Errorf("mismatched %th method: %s vs %s", i, xm, ym)
		// 	}
		// 	if err := equalType(xm.Type(), ym.Type()); err != nil {
		// 		return fmt.Errorf("mismatched %s method: %s", xm.Name(), err)
		// 	}
		// }
		if x.NumMethods() != y.NumMethods() {
			return fmt.Errorf("unequal methods: %d vs %d",
				x.NumMethods(), y.NumMethods())
		}
		for i := 0; i < x.NumMethods(); i++ {
			xm := x.Method(i)
			ym := y.Method(i)
			if xm.Name() != ym.Name() {
				return fmt.Errorf("mismatched %dth method: %s vs %s", i, xm, ym)
			}
			if err := equalType(xm.Type(), ym.Type()); err != nil {
				return fmt.Errorf("mismatched %s method: %s", xm.Name(), err)
			}
		}
		// Constraints are handled explicitly in the *TypeParam case below, so we
		// don't yet need to consider embeddeds here.
		// TODO(rfindley): consider the type set here.
	case *types.Array:
		y := y.(*types.Array)
		if x.Len() != y.Len() {
			return fmt.Errorf("unequal array lengths: %d vs %d", x.Len(), y.Len())
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("array elements: %s", err)
		}
	case *types.Basic:
		y := y.(*types.Basic)
		if x.Kind() != y.Kind() {
			return fmt.Errorf("unequal basic types: %s vs %s", x, y)
		}
	case *types.Chan:
		y := y.(*types.Chan)
		if x.Dir() != y.Dir() {
			return fmt.Errorf("unequal channel directions: %d vs %d", x.Dir(), y.Dir())
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("channel elements: %s", err)
		}
	case *types.Map:
		y := y.(*types.Map)
		if err := equalType(x.Key(), y.Key()); err != nil {
			return fmt.Errorf("map keys: %s", err)
		}
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("map values: %s", err)
		}
	case *types.Named:
		y := y.(*types.Named)
		return cmpNamed(x, y)
	case *types.Pointer:
		y := y.(*types.Pointer)
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("pointer elements: %s", err)
		}
	case *types.Signature:
		y := y.(*types.Signature)
		if err := equalType(x.Params(), y.Params()); err != nil {
			return fmt.Errorf("parameters: %s", err)
		}
		if err := equalType(x.Results(), y.Results()); err != nil {
			return fmt.Errorf("results: %s", err)
		}
		if x.Variadic() != y.Variadic() {
			return fmt.Errorf("unequal variadicity: %t vs %t",
				x.Variadic(), y.Variadic())
		}
		if (x.Recv() != nil) != (y.Recv() != nil) {
			return fmt.Errorf("unequal receivers: %s vs %s", x.Recv(), y.Recv())
		}
		if x.Recv() != nil {
			// TODO(adonovan): fix: this assertion fires for interface methods.
			// The type of the receiver of an interface method is a named type
			// if the Package was loaded from export data, or an unnamed (interface)
			// type if the Package was produced by type-checking ASTs.
			// if err := equalType(x.Recv().Type(), y.Recv().Type()); err != nil {
			// 	return fmt.Errorf("receiver: %s", err)
			// }
		}
		if err := equalTypeParams(x.TypeParams(), y.TypeParams()); err != nil {
			return fmt.Errorf("type params: %s", err)
		}
		if err := equalTypeParams(x.RecvTypeParams(), y.RecvTypeParams()); err != nil {
			return fmt.Errorf("recv type params: %s", err)
		}
	case *types.Slice:
		y := y.(*types.Slice)
		if err := equalType(x.Elem(), y.Elem()); err != nil {
			return fmt.Errorf("slice elements: %s", err)
		}
	case *types.Struct:
		y := y.(*types.Struct)
		if x.NumFields() != y.NumFields() {
			return fmt.Errorf("unequal struct fields: %d vs %d",
				x.NumFields(), y.NumFields())
		}
		for i := 0; i < x.NumFields(); i++ {
			xf := x.Field(i)
			yf := y.Field(i)
			if xf.Name() != yf.Name() {
				return fmt.Errorf("mismatched fields: %s vs %s", xf, yf)
			}
			if err := equalType(xf.Type(), yf.Type()); err != nil {
				return fmt.Errorf("struct field %s: %s", xf.Name(), err)
			}
			if x.Tag(i) != y.Tag(i) {
				return fmt.Errorf("struct field %s has unequal tags: %q vs %q",
					xf.Name(), x.Tag(i), y.Tag(i))
			}
		}
	case *types.Tuple:
		y := y.(*types.Tuple)
		if x.Len() != y.Len() {
			return fmt.Errorf("unequal tuple lengths: %d vs %d", x.Len(), y.Len())
		}
		for i := 0; i < x.Len(); i++ {
			if err := equalType(x.At(i).Type(), y.At(i).Type()); err != nil {
				return fmt.Errorf("tuple element %d: %s", i, err)
			}
		}
	case *types.TypeParam:
		y := y.(*types.TypeParam)
		if x.String() != y.String() {
			return fmt.Errorf("unequal named types: %s vs %s", x, y)
		}
		// For now, just compare constraints by type string to short-circuit
		// cycles. We have to make interfaces explicit as export data currently
		// doesn't support marking interfaces as implicit.
		// TODO(rfindley): remove makeExplicit once export data contains an
		// implicit bit.
		xc := makeExplicit(x.Constraint()).String()
		yc := makeExplicit(y.Constraint()).String()
		if xc != yc {
			return fmt.Errorf("unequal constraints: %s vs %s", xc, yc)
		}

	default:
		panic(fmt.Sprintf("unexpected %T type", x))
	}
	return nil
}

// cmpNamed compares two named types x and y, returning an error for any
// discrepancies. It does not compare their underlying types.
func cmpNamed(x, y *types.Named) error {
	xOrig := x.Origin()
	yOrig := y.Origin()
	if xOrig.String() != yOrig.String() {
		return fmt.Errorf("unequal named types: %s vs %s", x, y)
	}
	if err := equalTypeParams(x.TypeParams(), y.TypeParams()); err != nil {
		return fmt.Errorf("type parameters: %s", err)
	}
	if err := equalTypeArgs(x.TypeArgs(), y.TypeArgs()); err != nil {
		return fmt.Errorf("type arguments: %s", err)
	}
	if x.NumMethods() != y.NumMethods() {
		return fmt.Errorf("unequal methods: %d vs %d",
			x.NumMethods(), y.NumMethods())
	}
	// Unfortunately method sorting is not canonical, so sort before comparing.
	var xms, yms []*types.Func
	for i := 0; i < x.NumMethods(); i++ {
		xms = append(xms, x.Method(i))
		yms = append(yms, y.Method(i))
	}
	for _, ms := range [][]*types.Func{xms, yms} {
		sort.Slice(ms, func(i, j int) bool {
			return ms[i].Name() < ms[j].Name()
		})
	}
	for i, xm := range xms {
		ym := yms[i]
		if xm.Name() != ym.Name() {
			return fmt.Errorf("mismatched %dth method: %s vs %s", i, xm, ym)
		}
		// Calling equalType here leads to infinite recursion, so just compare
		// strings.
		if xm.String() != ym.String() {
			return fmt.Errorf("unequal methods: %s vs %s", x, y)
		}
	}
	return nil
}

// makeExplicit returns an explicit version of typ, if typ is an implicit
// interface. Otherwise it returns typ unmodified.
func makeExplicit(typ types.Type) types.Type {
	if iface, _ := typ.(*types.Interface); iface != nil && iface.IsImplicit() {
		var methods []*types.Func
		for i := 0; i < iface.NumExplicitMethods(); i++ {
			methods = append(methods, iface.Method(i))
		}
		var embeddeds []types.Type
		for etyp := range iface.EmbeddedTypes() {
			embeddeds = append(embeddeds, etyp)
		}
		return types.NewInterfaceType(methods, embeddeds)
	}
	return typ
}

func equalTypeArgs(x, y *types.TypeList) error {
	if x.Len() != y.Len() {
		return fmt.Errorf("unequal lengths: %d vs %d", x.Len(), y.Len())
	}
	for i := 0; i < x.Len(); i++ {
		if err := equalType(x.At(i), y.At(i)); err != nil {
			return fmt.Errorf("type %d: %s", i, err)
		}
	}
	return nil
}

func equalTypeParams(x, y *types.TypeParamList) error {
	if x.Len() != y.Len() {
		return fmt.Errorf("unequal lengths: %d vs %d", x.Len(), y.Len())
	}
	for i := 0; i < x.Len(); i++ {
		if err := equalType(x.At(i), y.At(i)); err != nil {
			return fmt.Errorf("type parameter %d: %s", i, err)
		}
	}
	return nil
}

// TestVeryLongFile tests the position of an import object declared in
// a very long input file.  Line numbers greater than maxlines are
// reported as line 1, not garbage or token.NoPos.
func TestVeryLongFile(t *testing.T) {
	// parse and typecheck
	longFile := "package foo" + strings.Repeat("\n", 123456) + "var X int"
	fset1 := token.NewFileSet()
	f, err := parser.ParseFile(fset1, "foo.go", longFile, 0)
	if err != nil {
		t.Fatal(err)
	}
	var conf types.Config
	pkg, err := conf.Check("foo", fset1, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// export
	var out bytes.Buffer
	if err := gcimporter.IExportData(&out, fset1, pkg); err != nil {
		t.Fatal(err)
	}
	exportdata := out.Bytes()

	// import
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg.Path())
	if err != nil {
		t.Fatalf("BImportData(%s): %v", pkg.Path(), err)
	}

	// compare
	posn1 := fset1.Position(pkg.Scope().Lookup("X").Pos())
	posn2 := fset2.Position(pkg2.Scope().Lookup("X").Pos())
	if want := "foo.go:1:1"; posn2.String() != want {
		t.Errorf("X position = %s, want %s (orig was %s)",
			posn2, want, posn1)
	}
}

const src = `
package p

type (
	T0 = int32
	T1 = struct{}
	T2 = struct{ T1 }
	Invalid = foo // foo is undeclared
)
`

func checkPkg(t *testing.T, pkg *types.Package, label string) {
	T1 := types.NewStruct(nil, nil)
	T2 := types.NewStruct([]*types.Var{types.NewField(0, pkg, "T1", T1, true)}, nil)

	for _, test := range []struct {
		name string
		typ  types.Type
	}{
		{"T0", types.Typ[types.Int32]},
		{"T1", T1},
		{"T2", T2},
		{"Invalid", types.Typ[types.Invalid]},
	} {
		obj := pkg.Scope().Lookup(test.name)
		if obj == nil {
			t.Errorf("%s: %s not found", label, test.name)
			continue
		}
		tname, _ := obj.(*types.TypeName)
		if tname == nil {
			t.Errorf("%s: %v not a type name", label, obj)
			continue
		}
		if !tname.IsAlias() {
			t.Errorf("%s: %v: not marked as alias", label, tname)
			continue
		}
		if got := tname.Type(); !types.Identical(got, test.typ) {
			t.Errorf("%s: %v: got %v; want %v", label, tname, got, test.typ)
		}
	}
}


================================================
FILE: internal/gcimporter/bimport.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the remaining vestiges of
// $GOROOT/src/go/internal/gcimporter/bimport.go.

package gcimporter

import (
	"fmt"
	"go/token"
	"go/types"
	"sync"
)

func errorf(format string, args ...any) {
	panic(fmt.Sprintf(format, args...))
}

const deltaNewFile = -64 // see cmd/compile/internal/gc/bexport.go

// Synthesize a token.Pos
type fakeFileSet struct {
	fset  *token.FileSet
	files map[string]*fileInfo
}

type fileInfo struct {
	file     *token.File
	lastline int
}

const maxlines = 64 * 1024

func (s *fakeFileSet) pos(file string, line, column int) token.Pos {
	_ = column // TODO(mdempsky): Make use of column.

	// Since we don't know the set of needed file positions, we reserve maxlines
	// positions per file. We delay calling token.File.SetLines until all
	// positions have been calculated (by way of fakeFileSet.setLines), so that
	// we can avoid setting unnecessary lines. See also golang/go#46586.
	f := s.files[file]
	if f == nil {
		f = &fileInfo{file: s.fset.AddFile(file, -1, maxlines)}
		s.files[file] = f
	}
	if line > maxlines {
		line = 1
	}
	if line > f.lastline {
		f.lastline = line
	}

	// Return a fake position assuming that f.file consists only of newlines.
	return token.Pos(f.file.Base() + line - 1)
}

func (s *fakeFileSet) setLines() {
	fakeLinesOnce.Do(func() {
		fakeLines = make([]int, maxlines)
		for i := range fakeLines {
			fakeLines[i] = i
		}
	})
	for _, f := range s.files {
		f.file.SetLines(fakeLines[:f.lastline])
	}
}

var (
	fakeLines     []int
	fakeLinesOnce sync.Once
)

func chanDir(d int) types.ChanDir {
	// tag values must match the constants in cmd/compile/internal/gc/go.go
	switch d {
	case 1 /* Crecv */ :
		return types.RecvOnly
	case 2 /* Csend */ :
		return types.SendOnly
	case 3 /* Cboth */ :
		return types.SendRecv
	default:
		errorf("unexpected channel dir %d", d)
		return 0
	}
}


================================================
FILE: internal/gcimporter/exportdata.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file should be kept in sync with $GOROOT/src/internal/exportdata/exportdata.go.
// This file also additionally implements FindExportData for gcexportdata.NewReader.

package gcimporter

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"go/build"
	"io"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
)

// FindExportData positions the reader r at the beginning of the
// export data section of an underlying cmd/compile created archive
// file by reading from it. The reader must be positioned at the
// start of the file before calling this function.
// This returns the length of the export data in bytes.
//
// This function is needed by [gcexportdata.Read], which must
// accept inputs produced by the last two releases of cmd/compile,
// plus tip.
func FindExportData(r *bufio.Reader) (size int64, err error) {
	arsize, err := FindPackageDefinition(r)
	if err != nil {
		return
	}
	size = int64(arsize)

	objapi, headers, err := ReadObjectHeaders(r)
	if err != nil {
		return
	}
	size -= int64(len(objapi))
	for _, h := range headers {
		size -= int64(len(h))
	}

	// Check for the binary export data section header "$$B\n".
	// TODO(taking): Unify with ReadExportDataHeader so that it stops at the 'u' instead of reading
	line, err := r.ReadSlice('\n')
	if err != nil {
		return
	}
	hdr := string(line)
	if hdr != "$$B\n" {
		err = fmt.Errorf("unknown export data header: %q", hdr)
		return
	}
	size -= int64(len(hdr))

	// For files with a binary export data header "$$B\n",
	// these are always terminated by an end-of-section marker "\n$$\n".
	// So the last bytes must always be this constant.
	//
	// The end-of-section marker is not a part of the export data itself.
	// Do not include these in size.
	//
	// It would be nice to have sanity check that the final bytes after
	// the export data are indeed the end-of-section marker. The split
	// of gcexportdata.NewReader and gcexportdata.Read make checking this
	// ugly so gcimporter gives up enforcing this. The compiler and go/types
	// importer do enforce this, which seems good enough.
	const endofsection = "\n$$\n"
	size -= int64(len(endofsection))

	if size < 0 {
		err = fmt.Errorf("invalid size (%d) in the archive file: %d bytes remain without section headers (recompile package)", arsize, size)
		return
	}

	return
}

// ReadUnified reads the contents of the unified export data from a reader r
// that contains the contents of a GC-created archive file.
//
// On success, the reader will be positioned after the end-of-section marker "\n$$\n".
//
// Supported GC-created archive files have 4 layers of nesting:
//   - An archive file containing a package definition file.
//   - The package definition file contains headers followed by a data section.
//     Headers are lines (≤ 4kb) that do not start with "$$".
//   - The data section starts with "$$B\n" followed by export data followed
//     by an end of section marker "\n$$\n". (The section start "$$\n" is no
//     longer supported.)
//   - The export data starts with a format byte ('u') followed by the <data> in
//     the given format. (See ReadExportDataHeader for older formats.)
//
// Putting this together, the bytes in a GC-created archive files are expected
// to look like the following.
// See cmd/internal/archive for more details on ar file headers.
//
// | <!arch>\n             | ar file signature
// | __.PKGDEF...size...\n | ar header for __.PKGDEF including size.
// | go object <...>\n     | objabi header
// | <optional headers>\n  | other headers such as build id
// | $$B\n                 | binary format marker
// | u<data>\n             | unified export <data>
// | $$\n                  | end-of-section marker
// | [optional padding]    | padding byte (0x0A) if size is odd
// | [ar file header]      | other ar files
// | [ar file data]        |
func ReadUnified(r *bufio.Reader) (data []byte, err error) {
	// We historically guaranteed headers at the default buffer size (4096) work.
	// This ensures we can use ReadSlice throughout.
	const minBufferSize = 4096
	r = bufio.NewReaderSize(r, minBufferSize)

	size, err := FindPackageDefinition(r)
	if err != nil {
		return
	}
	n := size

	objapi, headers, err := ReadObjectHeaders(r)
	if err != nil {
		return
	}
	n -= len(objapi)
	for _, h := range headers {
		n -= len(h)
	}

	hdrlen, err := ReadExportDataHeader(r)
	if err != nil {
		return
	}
	n -= hdrlen

	// size also includes the end of section marker. Remove that many bytes from the end.
	const marker = "\n$$\n"
	n -= len(marker)

	if n < 0 {
		err = fmt.Errorf("invalid size (%d) in the archive file: %d bytes remain without section headers (recompile package)", size, n)
		return
	}

	// Read n bytes from buf.
	data = make([]byte, n)
	_, err = io.ReadFull(r, data)
	if err != nil {
		return
	}

	// Check for marker at the end.
	var suffix [len(marker)]byte
	_, err = io.ReadFull(r, suffix[:])
	if err != nil {
		return
	}
	if s := string(suffix[:]); s != marker {
		err = fmt.Errorf("read %q instead of end-of-section marker (%q)", s, marker)
		return
	}

	return
}

// FindPackageDefinition positions the reader r at the beginning of a package
// definition file ("__.PKGDEF") within a GC-created archive by reading
// from it, and returns the size of the package definition file in the archive.
//
// The reader must be positioned at the start of the archive file before calling
// this function, and "__.PKGDEF" is assumed to be the first file in the archive.
//
// See cmd/internal/archive for details on the archive format.
func FindPackageDefinition(r *bufio.Reader) (size int, err error) {
	// Uses ReadSlice to limit risk of malformed inputs.

	// Read first line to make sure this is an object file.
	line, err := r.ReadSlice('\n')
	if err != nil {
		err = fmt.Errorf("can't find export data (%v)", err)
		return
	}

	// Is the first line an archive file signature?
	if string(line) != "!<arch>\n" {
		err = fmt.Errorf("not the start of an archive file (%q)", line)
		return
	}

	// package export block should be first
	size = readArchiveHeader(r, "__.PKGDEF")
	if size <= 0 {
		err = fmt.Errorf("not a package file")
		return
	}

	return
}

// ReadObjectHeaders reads object headers from the reader. Object headers are
// lines that do not start with an end-of-section marker "$$". The first header
// is the objabi header. On success, the reader will be positioned at the beginning
// of the end-of-section marker.
//
// It returns an error if any header does not fit in r.Size() bytes.
func ReadObjectHeaders(r *bufio.Reader) (objapi string, headers []string, err error) {
	// line is a temporary buffer for headers.
	// Use bounded reads (ReadSlice, Peek) to limit risk of malformed inputs.
	var line []byte

	// objapi header should be the first line
	if line, err = r.ReadSlice('\n'); err != nil {
		err = fmt.Errorf("can't find export data (%v)", err)
		return
	}
	objapi = string(line)

	// objapi header begins with "go object ".
	if !strings.HasPrefix(objapi, "go object ") {
		err = fmt.Errorf("not a go object file: %s", objapi)
		return
	}

	// process remaining object header lines
	for {
		// check for an end of section marker "$$"
		line, err = r.Peek(2)
		if err != nil {
			return
		}
		if string(line) == "$$" {
			return // stop
		}

		// read next header
		line, err = r.ReadSlice('\n')
		if err != nil {
			return
		}
		headers = append(headers, string(line))
	}
}

// ReadExportDataHeader reads the export data header and format from r.
// It returns the number of bytes read, or an error if the format is no longer
// supported or it failed to read.
//
// The only currently supported format is binary export data in the
// unified export format.
func ReadExportDataHeader(r *bufio.Reader) (n int, err error) {
	// Read export data header.
	line, err := r.ReadSlice('\n')
	if err != nil {
		return
	}

	hdr := string(line)
	switch hdr {
	case "$$\n":
		err = fmt.Errorf("old textual export format no longer supported (recompile package)")
		return

	case "$$B\n":
		var format byte
		format, err = r.ReadByte()
		if err != nil {
			return
		}
		// The unified export format starts with a 'u'.
		switch format {
		case 'u':
		default:
			// Older no longer supported export formats include:
			// indexed export format which started with an 'i'; and
			// the older binary export format which started with a 'c',
			// 'd', or 'v' (from "version").
			err = fmt.Errorf("binary export format %q is no longer supported (recompile package)", format)
			return
		}

	default:
		err = fmt.Errorf("unknown export data header: %q", hdr)
		return
	}

	n = len(hdr) + 1 // + 1 is for 'u'
	return
}

// FindPkg returns the filename and unique package id for an import
// path based on package information provided by build.Import (using
// the build.Default build.Context). A relative srcDir is interpreted
// relative to the current working directory.
//
// FindPkg is only used in tests within x/tools.
func FindPkg(path, srcDir string) (filename, id string, err error) {
	// TODO(taking): Move internal/exportdata.FindPkg into its own file,
	// and then this copy into a _test package.
	if path == "" {
		return "", "", errors.New("path is empty")
	}

	var noext string
	switch {
	default:
		// "x" -> "$GOPATH/pkg/$GOOS_$GOARCH/x.ext", "x"
		// Don't require the source files to be present.
		if abs, err := filepath.Abs(srcDir); err == nil { // see issue 14282
			srcDir = abs
		}
		var bp *build.Package
		bp, err = build.Import(path, srcDir, build.FindOnly|build.AllowBinary)
		if bp.PkgObj == "" {
			if bp.Goroot && bp.Dir != "" {
				filename, err = lookupGorootExport(bp.Dir)
				if err == nil {
					_, err = os.Stat(filename)
				}
				if err == nil {
					return filename, bp.ImportPath, nil
				}
			}
			goto notfound
		} else {
			noext = strings.TrimSuffix(bp.PkgObj, ".a")
		}
		id = bp.ImportPath

	case build.IsLocalImport(path):
		// "./x" -> "/this/directory/x.ext", "/this/directory/x"
		noext = filepath.Join(srcDir, path)
		id = noext

	case filepath.IsAbs(path):
		// for completeness only - go/build.Import
		// does not support absolute imports
		// "/x" -> "/x.ext", "/x"
		noext = path
		id = path
	}

	if false { // for debugging
		if path != id {
			fmt.Printf("%s -> %s\n", path, id)
		}
	}

	// try extensions
	for _, ext := range pkgExts {
		filename = noext + ext
		f, statErr := os.Stat(filename)
		if statErr == nil && !f.IsDir() {
			return filename, id, nil
		}
		if err == nil {
			err = statErr
		}
	}

notfound:
	if err == nil {
		return "", path, fmt.Errorf("can't find import: %q", path)
	}
	return "", path, fmt.Errorf("can't find import: %q: %w", path, err)
}

var pkgExts = [...]string{".a", ".o"} // a file from the build cache will have no extension

var exportMap sync.Map // package dir → func() (string, error)

// lookupGorootExport returns the location of the export data
// (normally found in the build cache, but located in GOROOT/pkg
// in prior Go releases) for the package located in pkgDir.
//
// (We use the package's directory instead of its import path
// mainly to simplify handling of the packages in src/vendor
// and cmd/vendor.)
//
// lookupGorootExport is only used in tests within x/tools.
func lookupGorootExport(pkgDir string) (string, error) {
	f, ok := exportMap.Load(pkgDir)
	if !ok {
		var (
			listOnce   sync.Once
			exportPath string
			err        error
		)
		f, _ = exportMap.LoadOrStore(pkgDir, func() (string, error) {
			listOnce.Do(func() {
				cmd := exec.Command(filepath.Join(build.Default.GOROOT, "bin", "go"), "list", "-export", "-f", "{{.Export}}", pkgDir)
				cmd.Dir = build.Default.GOROOT
				cmd.Env = append(os.Environ(), "PWD="+cmd.Dir, "GOROOT="+build.Default.GOROOT)
				var output []byte
				output, err = cmd.Output()
				if err != nil {
					if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
						err = errors.New(string(ee.Stderr))
					}
					return
				}

				exports := strings.Split(string(bytes.TrimSpace(output)), "\n")
				if len(exports) != 1 {
					err = fmt.Errorf("go list reported %d exports; expected 1", len(exports))
					return
				}

				exportPath = exports[0]
			})

			return exportPath, err
		})
	}

	return f.(func() (string, error))()
}


================================================
FILE: internal/gcimporter/gcimporter.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is a reduced copy of $GOROOT/src/go/internal/gcimporter/gcimporter.go.

// Package gcimporter provides various functions for reading
// gc-generated object files that can be used to implement the
// Importer interface defined by the Go 1.5 standard library package.
//
// The encoding is deterministic: if the encoder is applied twice to
// the same types.Package data structure, both encodings are equal.
// This property may be important to avoid spurious changes in
// applications such as build systems.
//
// However, the encoder is not necessarily idempotent. Importing an
// exported package may yield a types.Package that, while it
// represents the same set of Go types as the original, may differ in
// the details of its internal representation. Because of these
// differences, re-encoding the imported package may yield a
// different, but equally valid, encoding of the package.
package gcimporter // import "golang.org/x/tools/internal/gcimporter"

import (
	"bufio"
	"fmt"
	"go/token"
	"go/types"
	"io"
	"os"
)

const (
	// Enable debug during development: it adds some additional checks, and
	// prevents errors from being recovered.
	debug = false

	// If trace is set, debugging output is printed to std out.
	trace = false
)

// Import imports a gc-generated package given its import path and srcDir, adds
// the corresponding package object to the packages map, and returns the object.
// The packages map must contain all packages already imported.
//
// Import is only used in tests.
func Import(fset *token.FileSet, packages map[string]*types.Package, path, srcDir string, lookup func(path string) (io.ReadCloser, error)) (pkg *types.Package, err error) {
	var rc io.ReadCloser
	var id string
	if lookup != nil {
		// With custom lookup specified, assume that caller has
		// converted path to a canonical import path for use in the map.
		if path == "unsafe" {
			return types.Unsafe, nil
		}
		id = path

		// No need to re-import if the package was imported completely before.
		if pkg = packages[id]; pkg != nil && pkg.Complete() {
			return
		}
		f, err := lookup(path)
		if err != nil {
			return nil, err
		}
		rc = f
	} else {
		var filename string
		filename, id, err = FindPkg(path, srcDir)
		if filename == "" {
			if path == "unsafe" {
				return types.Unsafe, nil
			}
			return nil, err
		}

		// no need to re-import if the package was imported completely before
		if pkg = packages[id]; pkg != nil && pkg.Complete() {
			return
		}

		// open file
		f, err := os.Open(filename)
		if err != nil {
			return nil, err
		}
		defer func() {
			if err != nil {
				// add file name to error
				err = fmt.Errorf("%s: %v", filename, err)
			}
		}()
		rc = f
	}
	defer rc.Close()

	buf := bufio.NewReader(rc)
	data, err := ReadUnified(buf)
	if err != nil {
		err = fmt.Errorf("import %q: %v", path, err)
		return
	}

	// unified: emitted by cmd/compile since go1.20.
	_, pkg, err = UImportData(fset, packages, data, id)

	return
}


================================================
FILE: internal/gcimporter/gcimporter_test.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is a copy of $GOROOT/src/go/internal/gcimporter/gcimporter_test.go,
// adjusted to make it build with code from (std lib) internal/testenv copied.

package gcimporter_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/constant"
	goimporter "go/importer"
	goparser "go/parser"
	"go/token"
	"go/types"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/internal/gcimporter"
	"golang.org/x/tools/internal/goroot"
	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	testenv.ExitIfSmallMachine()
	os.Exit(m.Run())
}

// ----------------------------------------------------------------------------

func needsCompiler(t *testing.T, compiler string) {
	if runtime.Compiler == compiler {
		return
	}
	switch compiler {
	case "gc":
		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
	}
}

// compile runs the compiler on filename, with dirname as the working directory,
// and writes the output file to outdirname.
// compile gives the resulting package a packagepath of p.
func compile(t *testing.T, dirname, filename, outdirname string, packagefiles map[string]string) string {
	return compilePkg(t, dirname, filename, outdirname, packagefiles, "p")
}

func compilePkg(t *testing.T, dirname, filename, outdirname string, packagefiles map[string]string, pkg string) string {
	testenv.NeedsGoBuild(t)

	// filename must end with ".go"
	basename := strings.TrimSuffix(filepath.Base(filename), ".go")
	ok := filename != basename
	if !ok {
		t.Fatalf("filename doesn't end in .go: %s", filename)
	}
	objname := basename + ".o"
	outname := filepath.Join(outdirname, objname)

	importcfgfile := os.DevNull
	if len(packagefiles) > 0 {
		importcfgfile = filepath.Join(outdirname, basename) + ".importcfg"
		importcfg := new(bytes.Buffer)
		fmt.Fprintf(importcfg, "# import config")
		for k, v := range packagefiles {
			fmt.Fprintf(importcfg, "\npackagefile %s=%s\n", k, v)
		}
		if err := os.WriteFile(importcfgfile, importcfg.Bytes(), 0655); err != nil {
			t.Fatal(err)
		}
	}

	importreldir := strings.ReplaceAll(outdirname, string(os.PathSeparator), "/")
	cmd := exec.Command("go", "tool", "compile", "-p", pkg, "-D", importreldir, "-importcfg", importcfgfile, "-o", outname, filename)
	cmd.Dir = dirname
	if out, err := cmd.CombinedOutput(); err != nil {
		t.Logf("%s", out)
		t.Fatalf("go tool compile %s failed: %s", filename, err)
	}
	return outname
}

func testPath(t *testing.T, path, srcDir string) *types.Package {
	t0 := time.Now()
	pkg, err := gcimporter.Import(token.NewFileSet(), make(map[string]*types.Package), path, srcDir, nil)
	if err != nil {
		t.Errorf("testPath(%s): %s", path, err)
		return nil
	}
	t.Logf("testPath(%s): %v", path, time.Since(t0))
	return pkg
}

func mktmpdir(t *testing.T) string {
	tmpdir, err := os.MkdirTemp("", "gcimporter_test")
	if err != nil {
		t.Fatal("mktmpdir:", err)
	}
	if err := os.Mkdir(filepath.Join(tmpdir, "testdata"), 0700); err != nil {
		os.RemoveAll(tmpdir)
		t.Fatal("mktmpdir:", err)
	}
	return tmpdir
}

const testfile = "exports.go"

func TestImportTestdata(t *testing.T) {
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)

	packageFiles := map[string]string{}
	for _, pkg := range []string{"go/ast", "go/token"} {
		export, _, err := gcimporter.FindPkg(pkg, "testdata")
		if export == "" {
			t.Fatalf("no export data found for %s: %s", pkg, err)
		}
		packageFiles[pkg] = export
	}

	compile(t, "testdata", testfile, filepath.Join(tmpdir, "testdata"), packageFiles)

	// filename should end with ".go"
	filename := testfile[:len(testfile)-3]
	if pkg := testPath(t, "./testdata/"+filename, tmpdir); pkg != nil {
		// The package's Imports list must include all packages
		// explicitly imported by testfile, plus all packages
		// referenced indirectly via exported objects in testfile.
		// With the textual export format (when run against Go1.6),
		// the list may also include additional packages that are
		// not strictly required for import processing alone (they
		// are exported to err "on the safe side").
		// For now, we just test the presence of a few packages
		// that we know are there for sure.
		got := fmt.Sprint(pkg.Imports())
		wants := []string{"go/ast", "go/token", "go/ast"}
		for _, want := range wants {
			if !strings.Contains(got, want) {
				t.Errorf(`Package("exports").Imports() = %s, does not contain %s`, got, want)
			}
		}
	}
}

func TestImportTypeparamTests(t *testing.T) {
	if testing.Short() {
		t.Skipf("in short mode, skipping test that requires export data for all of std")
	}

	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
	testenv.NeedsGOROOTDir(t, "test")

	// This package only handles gc export data.
	if runtime.Compiler != "gc" {
		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
	}

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)

	// Check go files in test/typeparam, except those that fail for a known
	// reason.
	rootDir := filepath.Join(runtime.GOROOT(), "test", "typeparam")
	list, err := os.ReadDir(rootDir)
	if err != nil {
		t.Fatal(err)
	}

	for _, entry := range list {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".go") {
			// For now, only consider standalone go files.
			continue
		}

		t.Run(entry.Name(), func(t *testing.T) {
			filename := filepath.Join(rootDir, entry.Name())
			src, err := os.ReadFile(filename)
			if err != nil {
				t.Fatal(err)
			}
			if !bytes.HasPrefix(src, []byte("// run")) && !bytes.HasPrefix(src, []byte("// compile")) {
				// We're bypassing the logic of run.go here, so be conservative about
				// the files we consider in an attempt to make this test more robust to
				// changes in test/typeparams.
				t.Skipf("not detected as a run test")
			}

			// Compile and import, and compare the resulting package with the package
			// that was type-checked directly.
			pkgFiles, err := goroot.PkgfileMap()
			if err != nil {
				t.Fatal(err)
			}
			compile(t, rootDir, entry.Name(), filepath.Join(tmpdir, "testdata"), pkgFiles)
			pkgName := strings.TrimSuffix(entry.Name(), ".go")
			imported := importPkg(t, "./testdata/"+pkgName, tmpdir)
			checked := checkFile(t, filename, src)

			seen := make(map[string]bool)
			for _, name := range imported.Scope().Names() {
				if !token.IsExported(name) {
					continue // ignore synthetic names like .inittask and .dict.*
				}
				seen[name] = true

				importedObj := imported.Scope().Lookup(name)
				got := types.ObjectString(importedObj, types.RelativeTo(imported))

				checkedObj := checked.Scope().Lookup(name)
				if checkedObj == nil {
					t.Fatalf("imported object %q was not type-checked", name)
				}
				want := types.ObjectString(checkedObj, types.RelativeTo(checked))

				if got != want {
					t.Errorf("imported %q as %q, want %q", name, got, want)
				}
			}

			for _, name := range checked.Scope().Names() {
				if !token.IsExported(name) || seen[name] {
					continue
				}
				t.Errorf("did not import object %q", name)
			}
		})
	}
}

func checkFile(t *testing.T, filename string, src []byte) *types.Package {
	fset := token.NewFileSet()
	f, err := goparser.ParseFile(fset, filename, src, 0)
	if err != nil {
		t.Fatal(err)
	}
	config := types.Config{
		Importer: goimporter.Default(),
	}
	pkg, err := config.Check("", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}
	return pkg
}

func TestVersionHandling(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")

	const dir = "./testdata/versions"
	list, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	corruptdir := filepath.Join(tmpdir, "testdata", "versions")
	if err := os.Mkdir(corruptdir, 0700); err != nil {
		t.Fatal(err)
	}

	for _, f := range list {
		name := f.Name()
		if !strings.HasSuffix(name, ".a") {
			continue // not a package file
		}
		if strings.Contains(name, "corrupted") {
			continue // don't process a leftover corrupted file
		}
		pkgpath := "./" + name[:len(name)-2]

		if testing.Verbose() {
			t.Logf("importing %s", name)
		}

		// test that export data can be imported
		_, err := gcimporter.Import(token.NewFileSet(), make(map[string]*types.Package), pkgpath, dir, nil)
		if err != nil {
			t.Errorf("import %q failed: %v", pkgpath, err)
			continue
		}

		// create file with corrupted export data
		// 1) read file
		data, err := os.ReadFile(filepath.Join(dir, name))
		if err != nil {
			t.Fatal(err)
		}
		// 2) find export data
		// Index is an incorrect but 'good enough for tests' way to find the end of the export data.
		i := bytes.Index(data, []byte("\n$$B\n")) + 5
		j := bytes.Index(data[i:], []byte("\n$$\n")) + i
		if i < 0 || j < 0 || i > j {
			t.Fatalf("export data section not found (i = %d, j = %d)", i, j)
		}
		// 3) corrupt the data (increment every 7th byte)
		for k := j - 13; k >= i; k -= 7 {
			data[k]++
		}
		// 4) write the file
		pkgpath += "_corrupted"
		filename := filepath.Join(corruptdir, pkgpath) + ".a"
		os.WriteFile(filename, data, 0666)

		// test that importing the corrupted file results in an error
		_, err = gcimporter.Import(token.NewFileSet(), make(map[string]*types.Package), pkgpath, corruptdir, nil)
		if err == nil {
			t.Errorf("import corrupted %q succeeded", pkgpath)
		} else if msg := err.Error(); !strings.Contains(msg, "internal error") {
			t.Errorf("import %q error incorrect (%s)", pkgpath, msg)
		}
	}
}

func TestImportStdLib(t *testing.T) {
	if testing.Short() {
		t.Skip("the imports can be expensive, and this test is especially slow when the build cache is empty")
	}
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	// Get list of packages in stdlib. Filter out test-only packages with {{if .GoFiles}} check.
	var stderr bytes.Buffer
	cmd := exec.Command("go", "list", "-f", "{{if .GoFiles}}{{.ImportPath}}{{end}}", "std")
	cmd.Stderr = &stderr
	out, err := cmd.Output()
	if err != nil {
		t.Fatalf("failed to run go list to determine stdlib packages: %v\nstderr:\n%v", err, stderr.String())
	}
	pkgs := strings.Fields(string(out))

	var nimports int
	for _, pkg := range pkgs {
		t.Run(pkg, func(t *testing.T) {
			if testPath(t, pkg, filepath.Join(testenv.GOROOT(t), "src", path.Dir(pkg))) != nil {
				nimports++
			}
		})
	}
	const minPkgs = 225 // 'GOOS=plan9 go1.18 list std | wc -l' reports 228; most other platforms have more.
	if len(pkgs) < minPkgs {
		t.Fatalf("too few packages (%d) were imported", nimports)
	}

	t.Logf("tested %d imports", nimports)
}

var importedObjectTests = []struct {
	name string
	want string
}{
	// non-interfaces
	{"crypto.Hash", "type Hash uint"},
	{"go/ast.ObjKind", "type ObjKind int"},
	{"go/types.Qualifier", "type Qualifier func(*Package) string"},
	{"go/types.Comparable", "func Comparable(T Type) bool"},
	{"math.Pi", "const Pi untyped float"},
	{"math.Sin", "func Sin(x float64) float64"},
	{"go/ast.NotNilFilter", "func NotNilFilter(_ string, v reflect.Value) bool"},

	// interfaces
	{"context.Context", "type Context interface{Deadline() (deadline time.Time, ok bool); Done() <-chan struct{}; Err() error; Value(key any) any}"},
	{"crypto.Decrypter", "type Decrypter interface{Decrypt(rand io.Reader, msg []byte, opts DecrypterOpts) (plaintext []byte, err error); Public() PublicKey}"},
	{"encoding.BinaryMarshaler", "type BinaryMarshaler interface{MarshalBinary() (data []byte, err error)}"},
	{"io.Reader", "type Reader interface{Read(p []byte) (n int, err error)}"},
	{"io.ReadWriter", "type ReadWriter interface{Reader; Writer}"},
	{"go/ast.Node", "type Node interface{End() go/token.Pos; Pos() go/token.Pos}"},
	{"go/types.Type", "type Type interface{String() string; Underlying() Type}"},
}

func TestImportedTypes(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	for _, test := range importedObjectTests {
		obj := importObject(t, test.name)
		if obj == nil {
			continue // error reported elsewhere
		}
		got := types.ObjectString(obj, types.RelativeTo(obj.Pkg()))

		// TODO(rsc): Delete this block once go.dev/cl/368254 lands.
		if got != test.want && test.want == strings.ReplaceAll(got, "interface{}", "any") {
			got = test.want
		}

		if got != test.want {
			t.Errorf("%s: got %q; want %q", test.name, got, test.want)
		}

		if named, _ := types.Unalias(obj.Type()).(*types.Named); named != nil {
			verifyInterfaceMethodRecvs(t, named, 0)
		}
	}
}

func TestImportedConsts(t *testing.T) {
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	tests := []struct {
		name string
		want constant.Kind
	}{
		{"math.Pi", constant.Float},
		{"math.MaxFloat64", constant.Float},
		{"math.MaxInt64", constant.Int},
	}

	for _, test := range tests {
		obj := importObject(t, test.name)
		if got := obj.(*types.Const).Val().Kind(); got != test.want {
			t.Errorf("%s: imported as constant.Kind(%v), want constant.Kind(%v)", test.name, got, test.want)
		}
	}
}

// importObject imports the object specified by a name of the form
// <import path>.<object name>, e.g. go/types.Type.
//
// If any errors occur they are reported via t and the resulting object will
// be nil.
func importObject(t *testing.T, name string) types.Object {
	s := strings.Split(name, ".")
	if len(s) != 2 {
		t.Fatal("inconsistent test data")
	}
	importPath := s[0]
	objName := s[1]

	pkg, err := gcimporter.Import(token.NewFileSet(), make(map[string]*types.Package), importPath, ".", nil)
	if err != nil {
		t.Error(err)
		return nil
	}

	obj := pkg.Scope().Lookup(objName)
	if obj == nil {
		t.Errorf("%s: object not found", name)
		return nil
	}
	return obj
}

// verifyInterfaceMethodRecvs verifies that method receiver types
// are named if the methods belong to a named interface type.
func verifyInterfaceMethodRecvs(t *testing.T, named *types.Named, level int) {
	// avoid endless recursion in case of an embedding bug that lead to a cycle
	if level > 10 {
		t.Errorf("%s: embeds itself", named)
		return
	}

	iface, _ := named.Underlying().(*types.Interface)
	if iface == nil {
		return // not an interface
	}

	// check explicitly declared methods
	for m := range iface.ExplicitMethods() {
		recv := m.Type().(*types.Signature).Recv()
		if recv == nil {
			t.Errorf("%s: missing receiver type", m)
			continue
		}
		if recv.Type() != named {
			t.Errorf("%s: got recv type %s; want %s", m, recv.Type(), named)
		}
	}

	// check embedded interfaces (if they are named, too)
	for etyp := range iface.EmbeddedTypes() {
		// embedding of interfaces cannot have cycles; recursion will terminate
		if etype, _ := types.Unalias(etyp).(*types.Named); etype != nil {
			verifyInterfaceMethodRecvs(t, etype, level+1)
		}
	}
}

func TestIssue5815(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	pkg := importPkg(t, "strings", ".")

	scope := pkg.Scope()
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		if obj.Pkg() == nil {
			t.Errorf("no pkg for %s", obj)
		}
		if tname, _ := obj.(*types.TypeName); tname != nil {
			named := types.Unalias(tname.Type()).(*types.Named)
			for m := range named.Methods() {
				if m.Pkg() == nil {
					t.Errorf("no pkg for %s", m)
				}
			}
		}
	}
}

// Smoke test to ensure that imported methods get the correct package.
func TestCorrectMethodPackage(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	imports := make(map[string]*types.Package)
	_, err := gcimporter.Import(token.NewFileSet(), imports, "net/http", ".", nil)
	if err != nil {
		t.Fatal(err)
	}

	mutex := imports["sync"].Scope().Lookup("Mutex").(*types.TypeName).Type()
	mset := types.NewMethodSet(types.NewPointer(mutex)) // methods of *sync.Mutex
	sel := mset.Lookup(nil, "Lock")
	lock := sel.Obj().(*types.Func)
	if got, want := lock.Pkg().Path(), "sync"; got != want {
		t.Errorf("got package path %q; want %q", got, want)
	}
}

func TestIssue13566(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
	skipWindows(t)

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	testoutdir := filepath.Join(tmpdir, "testdata")

	// b.go needs to be compiled from the output directory so that the compiler can
	// find the compiled package a. We pass the full path to compile() so that we
	// don't have to copy the file to that directory.
	bpath, err := filepath.Abs(filepath.Join("testdata", "b.go"))
	if err != nil {
		t.Fatal(err)
	}

	jsonExport, _, err := gcimporter.FindPkg("encoding/json", "testdata")
	if jsonExport == "" {
		t.Fatalf("no export data found for encoding/json: %s", err)
	}

	compilePkg(t, "testdata", "a.go", testoutdir, map[string]string{"encoding/json": jsonExport}, apkg(testoutdir))
	compile(t, testoutdir, bpath, testoutdir, map[string]string{apkg(testoutdir): filepath.Join(testoutdir, "a.o")})

	// import must succeed (test for issue at hand)
	pkg := importPkg(t, "./testdata/b", tmpdir)

	// make sure all indirectly imported packages have names
	for _, imp := range pkg.Imports() {
		if imp.Name() == "" {
			t.Errorf("no name for %s package", imp.Path())
		}
	}
}

func TestIssue13898(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache

	// import go/internal/gcimporter which imports go/types partially
	imports := make(map[string]*types.Package)
	_, err := gcimporter.Import(token.NewFileSet(), imports, "go/internal/gcimporter", ".", nil)
	if err != nil {
		t.Fatal(err)
	}

	// look for go/types package
	var goTypesPkg *types.Package
	for path, pkg := range imports {
		if path == "go/types" {
			goTypesPkg = pkg
			break
		}
	}
	if goTypesPkg == nil {
		t.Fatal("go/types not found")
	}

	// look for go/types.Object type
	obj := lookupObj(t, goTypesPkg.Scope(), "Object")
	typ, ok := types.Unalias(obj.Type()).(*types.Named)
	if !ok {
		t.Fatalf("go/types.Object type is %v; wanted named type", typ)
	}

	// lookup go/types.Object.Pkg method
	m, index, indirect := types.LookupFieldOrMethod(typ, false, nil, "Pkg")
	if m == nil {
		t.Fatalf("go/types.Object.Pkg not found (index = %v, indirect = %v)", index, indirect)
	}

	// the method must belong to go/types
	if m.Pkg().Path() != "go/types" {
		t.Fatalf("found %v; want go/types", m.Pkg())
	}
}

func TestIssue15517(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)

	compile(t, "testdata", "p.go", filepath.Join(tmpdir, "testdata"), nil)

	// Multiple imports of p must succeed without redeclaration errors.
	// We use an import path that's not cleaned up so that the eventual
	// file path for the package is different from the package path; this
	// will expose the error if it is present.
	//
	// (Issue: Both the textual and the binary importer used the file path
	// of the package to be imported as key into the shared packages map.
	// However, the binary importer then used the package path to identify
	// the imported package to mark it as complete; effectively marking the
	// wrong package as complete. By using an "unclean" package path, the
	// file and package path are different, exposing the problem if present.
	// The same issue occurs with vendoring.)
	imports := make(map[string]*types.Package)
	for range 3 {
		if _, err := gcimporter.Import(token.NewFileSet(), imports, "./././testdata/p", tmpdir, nil); err != nil {
			t.Fatal(err)
		}
	}
}

func TestIssue15920(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	compileAndImportPkg(t, "issue15920")
}

func TestIssue20046(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	// "./issue20046".V.M must exist
	pkg := compileAndImportPkg(t, "issue20046")
	obj := lookupObj(t, pkg.Scope(), "V")
	if m, index, indirect := types.LookupFieldOrMethod(obj.Type(), false, nil, "M"); m == nil {
		t.Fatalf("V.M not found (index = %v, indirect = %v)", index, indirect)
	}
}

func TestIssue25301(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	compileAndImportPkg(t, "issue25301")
}

func TestIssue51836(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	testoutdir := filepath.Join(tmpdir, "testdata")

	dir := filepath.Join("testdata", "issue51836")
	// Following the pattern of TestIssue13898, aa.go needs to be compiled from
	// the output directory. We pass the full path to compile() so that we don't
	// have to copy the file to that directory.
	bpath, err := filepath.Abs(filepath.Join(dir, "aa.go"))
	if err != nil {
		t.Fatal(err)
	}
	compilePkg(t, dir, "a.go", testoutdir, nil, apkg(testoutdir))
	compile(t, testoutdir, bpath, testoutdir, map[string]string{apkg(testoutdir): filepath.Join(testoutdir, "a.o")})

	// import must succeed (test for issue at hand)
	_ = importPkg(t, "./testdata/aa", tmpdir)
}

func TestIssue61561(t *testing.T) {
	const src = `package p

type I[P any] interface {
	m(P)
	n() P
}

type J = I[int]

type StillBad[P any] *interface{b(P)}

type K = StillBad[string]
`
	fset := token.NewFileSet()
	f, err := goparser.ParseFile(fset, "p.go", src, 0)
	if f == nil {
		// Some test cases may have parse errors, but we must always have a
		// file.
		t.Fatalf("ParseFile returned nil file. Err: %v", err)
	}

	config := &types.Config{}
	pkg1, err := config.Check("p", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// Export it. (Shallowness isn't important here.)
	data, err := gcimporter.IExportShallow(fset, pkg1, nil)
	if err != nil {
		t.Fatalf("export: %v", err) // any failure to export is a bug
	}

	// Re-import it.
	imports := make(map[string]*types.Package)
	pkg2, err := gcimporter.IImportShallow(fset, gcimporter.GetPackagesFromMap(imports), data, "p", nil)
	if err != nil {
		t.Fatalf("import: %v", err) // any failure of IExport+IImport is a bug.
	}

	insts := []types.Type{
		pkg2.Scope().Lookup("J").Type(),
		// This test is still racy, because the incomplete interface is contained
		// within a nested type expression.
		//
		// Uncomment this once golang/go#61561 is fixed.
		// pkg2.Scope().Lookup("K").Type().Underlying().(*types.Pointer).Elem(),
	}

	// Use the interface instances concurrently.
	for _, inst := range insts {
		var wg sync.WaitGroup
		for range 2 {
			wg.Add(1)
			go func() {
				defer wg.Done()
				_ = types.NewMethodSet(inst)
			}()
		}
		wg.Wait()
	}
}

func TestIssue57015(t *testing.T) {
	// This package only handles gc export data.
	needsCompiler(t, "gc")
	skipWindows(t)

	compileAndImportPkg(t, "issue57015")
}

// This is a regression test for a failure to export a package
// containing type errors.
//
// Though the issues and tests are specific, they may be representatives of a
// class of exporter bugs on ill-typed code that we have yet to flush out.
//
// TODO(adonovan): systematize our search for similar problems using
// fuzz testing.
func TestExportInvalid(t *testing.T) {

	tests := []struct {
		name    string
		src     string
		objName string
	}{
		// The lack of a receiver causes Recv.Type=Invalid.
		// (The type checker then treats Foo as a package-level
		// function, inserting it into the package scope.)
		// The exporter needs to apply the same treatment.
		{"issue 57729", `package p; func () Foo() {}`, "Foo"},

		// It must be possible to export a constant with unknown kind, even if its
		// type is known.
		{"issue 60605", `package p; const EPSILON float64 = 1e-`, "EPSILON"},

		// We must not crash when exporting a struct with unknown package.
		{"issue 60891", `package p; type I[P any] int; const C I[struct{}] = 42`, "C"},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			// Parse the ill-typed input.
			fset := token.NewFileSet()

			f, err := goparser.ParseFile(fset, "p.go", test.src, 0)
			if f == nil {
				// Some test cases may have parse errors, but we must always have a
				// file.
				t.Fatalf("ParseFile returned nil file. Err: %v", err)
			}

			// Type check it, expecting errors.
			config := &types.Config{
				Error: func(err error) { t.Log(err) }, // don't abort at first error
			}
			pkg1, _ := config.Check("p", fset, []*ast.File{f}, nil)

			// Export it.
			// (Shallowness isn't important here.)
			data, err := gcimporter.IExportShallow(fset, pkg1, nil)
			if err != nil {
				t.Fatalf("export: %v", err) // any failure to export is a bug
			}

			// Re-import it.
			imports := make(map[string]*types.Package)
			pkg2, err := gcimporter.IImportShallow(fset, gcimporter.GetPackagesFromMap(imports), data, "p", nil)
			if err != nil {
				t.Fatalf("import: %v", err) // any failure of IExport+IImport is a bug.
			}

			// Check that the expected object is present in both packages.
			// We can't assert the type hasn't changed: it may have, in some cases.
			hasObj1 := pkg1.Scope().Lookup(test.objName) != nil
			hasObj2 := pkg2.Scope().Lookup(test.objName) != nil
			if hasObj1 != hasObj2 {
				t.Errorf("export+import changed Lookup(%q)!=nil: was %t, became %t", test.objName, hasObj1, hasObj2)
			}
		})
	}
}

func TestIssue58296(t *testing.T) {
	// Compiles packages c, b, and a where c imports b and b imports a,
	// then imports c with stub *types.Packages for b and a, and checks that
	// both a and b are in the Imports() of c.
	//
	// This is how go/packages can read the exportdata when NeedDeps is off.

	// This package only handles gc export data.
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
	skipWindows(t)

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	testoutdir := filepath.Join(tmpdir, "testdata")

	apkg := filepath.Join(testoutdir, "a")
	bpkg := filepath.Join(testoutdir, "b")
	cpkg := filepath.Join(testoutdir, "c")

	srcdir := filepath.Join("testdata", "issue58296")
	compilePkg(t, filepath.Join(srcdir, "a"), "a.go", testoutdir, nil, apkg)
	compilePkg(t, filepath.Join(srcdir, "b"), "b.go", testoutdir, map[string]string{apkg: filepath.Join(testoutdir, "a.o")}, bpkg)
	compilePkg(t, filepath.Join(srcdir, "c"), "c.go", testoutdir, map[string]string{bpkg: filepath.Join(testoutdir, "b.o")}, cpkg)

	// The export data reader for c cannot rely on Package.Imports
	// being populated for a or b. (For the imports {a,b} it is unset.)
	imports := map[string]*types.Package{
		apkg: types.NewPackage(apkg, "a"),
		bpkg: types.NewPackage(bpkg, "b"),
	}

	// make sure a and b are both imported by c.
	pkg, err := gcimporter.Import(token.NewFileSet(), imports, "./c", testoutdir, nil)
	if err != nil {
		t.Fatal(err)
	}

	var names []string
	for _, imp := range pkg.Imports() {
		names = append(names, imp.Name())
	}
	sort.Strings(names)

	if got, want := strings.Join(names, ","), "a,b"; got != want {
		t.Errorf("got imports %v for package c. wanted %v", names, want)
	}
}

func TestIssueAliases(t *testing.T) {
	// This package only handles gc export data.
	testenv.NeedsGo1Point(t, 24)
	needsCompiler(t, "gc")
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
	skipWindows(t)

	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	testoutdir := filepath.Join(tmpdir, "testdata")

	apkg := filepath.Join(testoutdir, "a")
	bpkg := filepath.Join(testoutdir, "b")
	cpkg := filepath.Join(testoutdir, "c")

	// compile a, b and c into gc export data.
	srcdir := filepath.Join("testdata", "aliases")
	compilePkg(t, filepath.Join(srcdir, "a"), "a.go", testoutdir, nil, apkg)
	compilePkg(t, filepath.Join(srcdir, "b"), "b.go", testoutdir, map[string]string{apkg: filepath.Join(testoutdir, "a.o")}, bpkg)
	compilePkg(t, filepath.Join(srcdir, "c"), "c.go", testoutdir,
		map[string]string{apkg: filepath.Join(testoutdir, "a.o"), bpkg: filepath.Join(testoutdir, "b.o")},
		cpkg,
	)

	// import c from gc export data using a and b.
	pkg, err := gcimporter.Import(token.NewFileSet(), map[string]*types.Package{
		apkg: types.NewPackage(apkg, "a"),
		bpkg: types.NewPackage(bpkg, "b"),
	}, "./c", testoutdir, nil)
	if err != nil {
		t.Fatal(err)
	}

	// Check c's objects and types.
	var objs []string
	for _, imp := range pkg.Scope().Names() {
		obj := pkg.Scope().Lookup(imp)
		s := fmt.Sprintf("%s : %s", obj.Name(), obj.Type())
		s = strings.ReplaceAll(s, testoutdir, "testdata")
		objs = append(objs, s)
	}
	sort.Strings(objs)

	want := strings.Join([]string{
		"S : struct{F int}",
		"T : struct{F int}",
		"U : testdata/a.A[string]",
		"V : testdata/a.A[int]",
		"W : testdata/b.B[string]",
		"X : testdata/b.B[int]",
		"Y : testdata/c.c[string]",
		"Z : testdata/c.c[int]",
		"c : testdata/c.c[V any]",
	}, ",")
	if got := strings.Join(objs, ","); got != want {
		t.Errorf("got imports %v for package c. wanted %v", objs, want)
	}
}

// apkg returns the package "a" prefixed by (as a package) testoutdir
func apkg(testoutdir string) string {
	apkg := testoutdir + "/a"
	if os.PathSeparator != '/' {
		apkg = strings.ReplaceAll(apkg, string(os.PathSeparator), "/")
	}
	return apkg
}

func importPkg(t *testing.T, path, srcDir string) *types.Package {
	pkg, err := gcimporter.Import(token.NewFileSet(), make(map[string]*types.Package), path, srcDir, nil)
	if err != nil {
		t.Fatal(err)
	}
	return pkg
}

func compileAndImportPkg(t *testing.T, name string) *types.Package {
	tmpdir := mktmpdir(t)
	defer os.RemoveAll(tmpdir)
	compile(t, "testdata", name+".go", filepath.Join(tmpdir, "testdata"), nil)
	return importPkg(t, "./testdata/"+name, tmpdir)
}

func lookupObj(t *testing.T, scope *types.Scope, name string) types.Object {
	if obj := scope.Lookup(name); obj != nil {
		return obj
	}
	t.Fatalf("%s not found", name)
	return nil
}

// skipWindows skips the test on windows.
//
// On windows, we have to set the -D option for the compiler to avoid having a drive
// letter and an illegal ':' in the import path - just skip it (see also issue #3483).
func skipWindows(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("avoid dealing with relative paths/drive letters on windows")
	}
}

type importMap map[string]*types.Package

func (m importMap) Import(path string) (*types.Package, error) { return m[path], nil }

func TestIssue69912(t *testing.T) {
	fset := token.NewFileSet()

	check := func(pkgname, src string, imports importMap) (*types.Package, error) {
		f, err := goparser.ParseFile(fset, "a.go", src, 0)
		if err != nil {
			return nil, err
		}
		config := &types.Config{
			Importer: imports,
		}
		return config.Check(pkgname, fset, []*ast.File{f}, nil)
	}

	const libSrc = `package lib

type T int
`

	lib, err := check("lib", libSrc, nil)
	if err != nil {
		t.Fatalf("Checking lib: %v", err)
	}

	// Export it.
	var out bytes.Buffer
	if err := gcimporter.IExportData(&out, fset, lib); err != nil {
		t.Fatalf("export: %v", err) // any failure to export is a bug
	}

	// Re-import it.
	imports := make(map[string]*types.Package)
	_, lib2, err := gcimporter.IImportData(fset, imports, out.Bytes(), "lib")
	if err != nil {
		t.Fatalf("import: %v", err) // any failure of export+import is a bug.
	}

	// Use the resulting package concurrently, via dot-imports.

	const pSrc = `package p

import . "lib"

type S struct {
	f T
}
`
	importer := importMap{
		"lib": lib2,
	}
	var wg sync.WaitGroup
	for range 10 {
		wg.Add(1)
		go func() {
			defer wg.Done()
			_, err := check("p", pSrc, importer)
			if err != nil {
				t.Errorf("check failed: %v", err)
			}
		}()
	}
	wg.Wait()
}


================================================
FILE: internal/gcimporter/iexport.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Indexed package export.
//
// The indexed export data format is an evolution of the previous
// binary export data format. Its chief contribution is introducing an
// index table, which allows efficient random access of individual
// declarations and inline function bodies. In turn, this allows
// avoiding unnecessary work for compilation units that import large
// packages.
//
//
// The top-level data format is structured as:
//
//     Header struct {
//         Tag        byte   // 'i'
//         Version    uvarint
//         StringSize uvarint
//         DataSize   uvarint
//     }
//
//     Strings [StringSize]byte
//     Data    [DataSize]byte
//
//     MainIndex []struct{
//         PkgPath   stringOff
//         PkgName   stringOff
//         PkgHeight uvarint
//
//         Decls []struct{
//             Name   stringOff
//             Offset declOff
//         }
//     }
//
//     Fingerprint [8]byte
//
// uvarint means a uint64 written out using uvarint encoding.
//
// []T means a uvarint followed by that many T objects. In other
// words:
//
//     Len   uvarint
//     Elems [Len]T
//
// stringOff means a uvarint that indicates an offset within the
// Strings section. At that offset is another uvarint, followed by
// that many bytes, which form the string value.
//
// declOff means a uvarint that indicates an offset within the Data
// section where the associated declaration can be found.
//
//
// There are five kinds of declarations, distinguished by their first
// byte:
//
//     type Var struct {
//         Tag  byte // 'V'
//         Pos  Pos
//         Type typeOff
//     }
//
//     type Func struct {
//         Tag       byte // 'F' or 'G'
//         Pos       Pos
//         TypeParams []typeOff  // only present if Tag == 'G'
//         Signature Signature
//     }
//
//     type Const struct {
//         Tag   byte // 'C'
//         Pos   Pos
//         Value Value
//     }
//
//     type Type struct {
//         Tag        byte // 'T' or 'U'
//         Pos        Pos
//         TypeParams []typeOff  // only present if Tag == 'U'
//         Underlying typeOff
//
//         Methods []struct{  // omitted if Underlying is an interface type
//             Pos       Pos
//             Name      stringOff
//             Recv      Param
//             Signature Signature
//         }
//     }
//
//     type Alias struct {
//         Tag  byte // 'A' or 'B'
//         Pos  Pos
//         TypeParams []typeOff  // only present if Tag == 'B'
//         Type typeOff
//     }
//
//     // "Automatic" declaration of each typeparam
//     type TypeParam struct {
//         Tag        byte // 'P'
//         Pos        Pos
//         Implicit   bool
//         Constraint typeOff
//     }
//
// typeOff means a uvarint that either indicates a predeclared type,
// or an offset into the Data section. If the uvarint is less than
// predeclReserved, then it indicates the index into the predeclared
// types list (see predeclared in bexport.go for order). Otherwise,
// subtracting predeclReserved yields the offset of a type descriptor.
//
// Value means a type, kind, and type-specific value. See
// (*exportWriter).value for details.
//
//
// There are twelve kinds of type descriptors, distinguished by an itag:
//
//     type DefinedType struct {
//         Tag     itag // definedType
//         Name    stringOff
//         PkgPath stringOff
//     }
//
//     type PointerType struct {
//         Tag  itag // pointerType
//         Elem typeOff
//     }
//
//     type SliceType struct {
//         Tag  itag // sliceType
//         Elem typeOff
//     }
//
//     type ArrayType struct {
//         Tag  itag // arrayType
//         Len  uint64
//         Elem typeOff
//     }
//
//     type ChanType struct {
//         Tag  itag   // chanType
//         Dir  uint64 // 1 RecvOnly; 2 SendOnly; 3 SendRecv
//         Elem typeOff
//     }
//
//     type MapType struct {
//         Tag  itag // mapType
//         Key  typeOff
//         Elem typeOff
//     }
//
//     type FuncType struct {
//         Tag       itag // signatureType
//         PkgPath   stringOff
//         Signature Signature
//     }
//
//     type StructType struct {
//         Tag     itag // structType
//         PkgPath stringOff
//         Fields []struct {
//             Pos      Pos
//             Name     stringOff
//             Type     typeOff
//             Embedded bool
//             Note     stringOff
//         }
//     }
//
//     type InterfaceType struct {
//         Tag     itag // interfaceType
//         PkgPath stringOff
//         Embeddeds []struct {
//             Pos  Pos
//             Type typeOff
//         }
//         Methods []struct {
//             Pos       Pos
//             Name      stringOff
//             Signature Signature
//         }
//     }
//
//     // Reference to a type param declaration
//     type TypeParamType struct {
//         Tag     itag // typeParamType
//         Name    stringOff
//         PkgPath stringOff
//     }
//
//     // Instantiation of a generic type (like List[T2] or List[int])
//     type InstanceType struct {
//         Tag     itag // instanceType
//         Pos     pos
//         TypeArgs []typeOff
//         BaseType typeOff
//     }
//
//     type UnionType struct {
//         Tag     itag // interfaceType
//         Terms   []struct {
//             tilde bool
//             Type  typeOff
//         }
//     }
//
//
//
//     type Signature struct {
//         Params   []Param
//         Results  []Param
//         Variadic bool  // omitted if Results is empty
//     }
//
//     type Param struct {
//         Pos  Pos
//         Name stringOff
//         Type typOff
//     }
//
//
// Pos encodes a file:line:column triple, incorporating a simple delta
// encoding scheme within a data object. See exportWriter.pos for
// details.

package gcimporter

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"io"
	"math/big"
	"reflect"
	"slices"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/tools/go/types/objectpath"
)

// IExportShallow encodes "shallow" export data for the specified package.
//
// For types, we use "shallow" export data. Historically, the Go
// compiler always produced a summary of the types for a given package
// that included types from other packages that it indirectly
// referenced: "deep" export data. This had the advantage that the
// compiler (and analogous tools such as gopls) need only load one
// file per direct import.  However, it meant that the files tended to
// get larger based on the level of the package in the import
// graph. For example, higher-level packages in the kubernetes module
// have over 1MB of "deep" export data, even when they have almost no
// content of their own, merely because they mention a major type that
// references many others. In pathological cases the export data was
// 300x larger than the source for a package due to this quadratic
// growth.
//
// "Shallow" export data means that the serialized types describe only
// a single package. If those types mention types from other packages,
// the type checker may need to request additional packages beyond
// just the direct imports. Type information for the entire transitive
// closure of imports is provided (lazily) by the DAG.
//
// No promises are made about the encoding other than that it can be decoded by
// the same version of IIExportShallow. If you plan to save export data in the
// file system, be sure to include a cryptographic digest of the executable in
// the key to avoid version skew.
//
// If the provided reportf func is non-nil, it is used for reporting
// bugs (e.g. recovered panics) encountered during export, enabling us
// to obtain via telemetry the stack that would otherwise be lost by
// merely returning an error.
func IExportShallow(fset *token.FileSet, pkg *types.Package, reportf ReportFunc) ([]byte, error) {
	// In principle this operation can only fail if out.Write fails,
	// but that's impossible for bytes.Buffer---and as a matter of
	// fact iexportCommon doesn't even check for I/O errors.
	// TODO(adonovan): handle I/O errors properly.
	// TODO(adonovan): use byte slices throughout, avoiding copying.
	const bundle, shallow = false, true
	var out bytes.Buffer
	err := iexportCommon(&out, fset, bundle, shallow, iexportVersion, []*types.Package{pkg}, reportf)
	return out.Bytes(), err
}

// IImportShallow decodes "shallow" types.Package data encoded by
// [IExportShallow] in the same executable. This function cannot import data
// from cmd/compile or gcexportdata.Write.
//
// The importer calls getPackages to obtain package symbols for all
// packages mentioned in the export data, including the one being
// decoded.
//
// If the provided reportf func is non-nil, it will be used for reporting bugs
// encountered during import.
// TODO(rfindley): remove reportf when we are confident enough in the new
// objectpath encoding.
func IImportShallow(fset *token.FileSet, getPackages GetPackagesFunc, data []byte, path string, reportf ReportFunc) (*types.Package, error) {
	const bundle = false
	const shallow = true
	pkgs, err := iimportCommon(fset, getPackages, data, bundle, path, shallow, reportf)
	if err != nil {
		return nil, err
	}
	return pkgs[0], nil
}

// ReportFunc is the type of a function used to report formatted bugs.
type ReportFunc = func(string, ...any)

// Current bundled export format version. Increase with each format change.
// 0: initial implementation
const bundleVersion = 0

// IExportData writes indexed export data for pkg to out.
//
// If no file set is provided, position info will be missing.
// The package path of the top-level package will not be recorded,
// so that calls to IImportData can override with a provided package path.
func IExportData(out io.Writer, fset *token.FileSet, pkg *types.Package) error {
	const bundle, shallow = false, false
	return iexportCommon(out, fset, bundle, shallow, iexportVersion, []*types.Package{pkg}, nil)
}

// IExportBundle writes an indexed export bundle for pkgs to out.
func IExportBundle(out io.Writer, fset *token.FileSet, pkgs []*types.Package) error {
	const bundle, shallow = true, false
	return iexportCommon(out, fset, bundle, shallow, iexportVersion, pkgs, nil)
}

func iexportCommon(out io.Writer, fset *token.FileSet, bundle, shallow bool, version int, pkgs []*types.Package, reportf ReportFunc) (err error) {
	if !debug {
		defer func() {
			if e := recover(); e != nil {
				// Report the stack via telemetry (see #71067).
				if reportf != nil {
					reportf("panic in exporter")
				}
				if ierr, ok := e.(internalError); ok {
					// internalError usually means we exported a
					// bad go/types data structure: a violation
					// of an implicit precondition of Export.
					err = ierr
					return
				}
				// Not an internal error; panic again.
				panic(e)
			}
		}()
	}

	p := iexporter{
		fset:        fset,
		version:     version,
		shallow:     shallow,
		allPkgs:     map[*types.Package]bool{},
		stringIndex: map[string]uint64{},
		declIndex:   map[types.Object]uint64{},
		tparamNames: map[types.Object]string{},
		typIndex:    map[types.Type]uint64{},
	}
	if !bundle {
		p.localpkg = pkgs[0]
	}

	for i, pt := range predeclared() {
		p.typIndex[pt] = uint64(i)
	}
	if len(p.typIndex) > predeclReserved {
		panic(internalErrorf("too many predeclared types: %d > %d", len(p.typIndex), predeclReserved))
	}

	// Initialize work queue with exported declarations.
	for _, pkg := range pkgs {
		scope := pkg.Scope()
		for _, name := range scope.Names() {
			if token.IsExported(name) {
				p.pushDecl(scope.Lookup(name))
			}
		}

		if bundle {
			// Ensure pkg and its imports are included in the index.
			p.allPkgs[pkg] = true
			for _, imp := range pkg.Imports() {
				p.allPkgs[imp] = true
			}
		}
	}

	// Loop until no more work.
	for !p.declTodo.empty() {
		p.doDecl(p.declTodo.popHead())
	}

	// Produce index of offset of each file record in files.
	var files intWriter
	var fileOffset []uint64 // fileOffset[i] is offset in files of file encoded as i
	if p.shallow {
		fileOffset = make([]uint64, len(p.fileInfos))
		for i, info := range p.fileInfos {
			fileOffset[i] = uint64(files.Len())
			p.encodeFile(&files, info.file, info.needed)
		}
	}

	// Append indices to data0 section.
	dataLen := uint64(p.data0.Len())
	w := p.newWriter()
	w.writeIndex(p.declIndex)

	if bundle {
		w.uint64(uint64(len(pkgs)))
		for _, pkg := range pkgs {
			w.pkg(pkg)
			imps := pkg.Imports()
			w.uint64(uint64(len(imps)))
			for _, imp := range imps {
				w.pkg(imp)
			}
		}
	}
	w.flush()

	// Assemble header.
	var hdr intWriter
	if bundle {
		hdr.uint64(bundleVersion)
	}
	hdr.uint64(uint64(p.version))
	hdr.uint64(uint64(p.strings.Len()))
	if p.shallow {
		hdr.uint64(uint64(files.Len()))
		hdr.uint64(uint64(len(fileOffset)))
		for _, offset := range fileOffset {
			hdr.uint64(offset)
		}
	}
	hdr.uint64(dataLen)

	// Flush output.
	io.Copy(out, &hdr)
	io.Copy(out, &p.strings)
	if p.shallow {
		io.Copy(out, &files)
	}
	io.Copy(out, &p.data0)

	return nil
}

// encodeFile writes to w a representation of the file sufficient to
// faithfully restore position information about all needed offsets.
// Mutates the needed array.
func (p *iexporter) encodeFile(w *intWriter, file *token.File, needed []uint64) {
	_ = needed[0] // precondition: needed is non-empty

	w.uint64(p.stringOff(file.Name()))

	size := uint64(file.Size())
	w.uint64(size)

	// Sort the set of needed offsets. Duplicates are harmless.
	slices.Sort(needed)

	lines := file.Lines() // byte offset of each line start
	w.uint64(uint64(len(lines)))

	// Rather than record the entire array of line start offsets,
	// we save only a sparse list of (index, offset) pairs for
	// the start of each line that contains a needed position.
	var sparse [][2]int // (index, offset) pairs
outer:
	for i, lineStart := range lines {
		lineEnd := size
		if i < len(lines)-1 {
			lineEnd = uint64(lines[i+1])
		}
		// Does this line contains a needed offset?
		if needed[0] < lineEnd {
			sparse = append(sparse, [2]int{i, lineStart})
			for needed[0] < lineEnd {
				needed = needed[1:]
				if len(needed) == 0 {
					break outer
				}
			}
		}
	}

	// Delta-encode the columns.
	w.uint64(uint64(len(sparse)))
	var prev [2]int
	for _, pair := range sparse {
		w.uint64(uint64(pair[0] - prev[0]))
		w.uint64(uint64(pair[1] - prev[1]))
		prev = pair
	}
}

// writeIndex writes out an object index. mainIndex indicates whether
// we're writing out the main index, which is also read by
// non-compiler tools and includes a complete package description
// (i.e., name and height).
func (w *exportWriter) writeIndex(index map[types.Object]uint64) {
	type pkgObj struct {
		obj  types.Object
		name string // qualified name; differs from obj.Name for type params
	}
	// Build a map from packages to objects from that package.
	pkgObjs := map[*types.Package][]pkgObj{}

	// For the main index, make sure to include every package that
	// we reference, even if we're not exporting (or reexporting)
	// any symbols from it.
	if w.p.localpkg != nil {
		pkgObjs[w.p.localpkg] = nil
	}
	for pkg := range w.p.allPkgs {
		pkgObjs[pkg] = nil
	}

	for obj := range index {
		name := w.p.exportName(obj)
		pkgObjs[obj.Pkg()] = append(pkgObjs[obj.Pkg()], pkgObj{obj, name})
	}

	var pkgs []*types.Package
	for pkg, objs := range pkgObjs {
		pkgs = append(pkgs, pkg)

		sort.Slice(objs, func(i, j int) bool {
			return objs[i].name < objs[j].name
		})
	}

	sort.Slice(pkgs, func(i, j int) bool {
		return w.exportPath(pkgs[i]) < w.exportPath(pkgs[j])
	})

	w.uint64(uint64(len(pkgs)))
	for _, pkg := range pkgs {
		w.string(w.exportPath(pkg))
		w.string(pkg.Name())
		w.uint64(uint64(0)) // package height is not needed for go/types

		objs := pkgObjs[pkg]
		w.uint64(uint64(len(objs)))
		for _, obj := range objs {
			w.string(obj.name)
			w.uint64(index[obj.obj])
		}
	}
}

// exportName returns the 'exported' name of an object. It differs from
// obj.Name() only for type parameters (see tparamExportName for details).
func (p *iexporter) exportName(obj types.Object) (res string) {
	if name := p.tparamNames[obj]; name != "" {
		return name
	}
	return obj.Name()
}

type iexporter struct {
	fset    *token.FileSet
	version int

	shallow    bool                // don't put types from other packages in the index
	objEncoder *objectpath.Encoder // encodes objects from other packages in shallow mode; lazily allocated
	localpkg   *types.Package      // (nil in bundle mode)

	// allPkgs tracks all packages that have been referenced by
	// the export data, so we can ensure to include them in the
	// main index.
	allPkgs map[*types.Package]bool

	declTodo objQueue

	strings     intWriter
	stringIndex map[string]uint64

	// In shallow mode, object positions are encoded as (file, offset).
	// Each file is recorded as a line-number table.
	// Only the lines of needed positions are saved faithfully.
	fileInfo  map[*token.File]uint64 // value is index in fileInfos
	fileInfos []*filePositions

	data0       intWriter
	declIndex   map[types.Object]uint64
	tparamNames map[types.Object]string // typeparam->exported name
	typIndex    map[types.Type]uint64

	indent int // for tracing support
}

type filePositions struct {
	file   *token.File
	needed []uint64 // unordered list of needed file offsets
}

func (p *iexporter) trace(format string, args ...any) {
	if !trace {
		// Call sites should also be guarded, but having this check here allows
		// easily enabling/disabling debug trace statements.
		return
	}
	fmt.Printf(strings.Repeat("..", p.indent)+format+"\n", args...)
}

// objectpathEncoder returns the lazily allocated objectpath.Encoder to use
// when encoding objects in other packages during shallow export.
//
// Using a shared Encoder amortizes some of cost of objectpath search.
func (p *iexporter) objectpathEncoder() *objectpath.Encoder {
	if p.objEncoder == nil {
		p.objEncoder = new(objectpath.Encoder)
	}
	return p.objEncoder
}

// stringOff returns the offset of s within the string section.
// If not already present, it's added to the end.
func (p *iexporter) stringOff(s string) uint64 {
	off, ok := p.stringIndex[s]
	if !ok {
		off = uint64(p.strings.Len())
		p.stringIndex[s] = off

		p.strings.uint64(uint64(len(s)))
		p.strings.WriteString(s)
	}
	return off
}

// fileIndexAndOffset returns the index of the token.File and the byte offset of pos within it.
func (p *iexporter) fileIndexAndOffset(file *token.File, pos token.Pos) (uint64, uint64) {
	index, ok := p.fileInfo[file]
	if !ok {
		index = uint64(len(p.fileInfo))
		p.fileInfos = append(p.fileInfos, &filePositions{file: file})
		if p.fileInfo == nil {
			p.fileInfo = make(map[*token.File]uint64)
		}
		p.fileInfo[file] = index
	}
	// Record each needed offset.
	info := p.fileInfos[index]
	offset := uint64(file.Offset(pos))
	info.needed = append(info.needed, offset)

	return index, offset
}

// pushDecl adds n to the declaration work queue, if not already present.
func (p *iexporter) pushDecl(obj types.Object) {
	// Package unsafe is known to the compiler and predeclared.
	// Caller should not ask us to do export it.
	if obj.Pkg() == types.Unsafe {
		panic("cannot export package unsafe")
	}

	// Shallow export data: don't index decls from other packages.
	if p.shallow && obj.Pkg() != p.localpkg {
		return
	}

	if _, ok := p.declIndex[obj]; ok {
		return
	}

	p.declIndex[obj] = ^uint64(0) // mark obj present in work queue
	p.declTodo.pushTail(obj)
}

// exportWriter handles writing out individual data section chunks.
type exportWriter struct {
	p *iexporter

	data       intWriter
	prevFile   string
	prevLine   int64
	prevColumn int64
}

func (w *exportWriter) exportPath(pkg *types.Package) string {
	if pkg == w.p.localpkg {
		return ""
	}
	return pkg.Path()
}

func (p *iexporter) doDecl(obj types.Object) {
	if trace {
		p.trace("exporting decl %v (%T)", obj, obj)
		p.indent++
		defer func() {
			p.indent--
			p.trace("=> %s", obj)
		}()
	}
	w := p.newWriter()

	switch obj := obj.(type) {
	case *types.Var:
		w.tag(varTag)
		w.pos(obj.Pos())
		w.typ(obj.Type(), obj.Pkg())

	case *types.Func:
		sig, _ := obj.Type().(*types.Signature)
		if sig.Recv() != nil {
			// We shouldn't see methods in the package scope,
			// but the type checker may repair "func () F() {}"
			// to "func (Invalid) F()" and then treat it like "func F()",
			// so allow that. See golang/go#57729.
			if sig.Recv().Type() != types.Typ[types.Invalid] {
				panic(internalErrorf("unexpected method: %v", sig))
			}
		}

		// Function.
		if sig.TypeParams().Len() == 0 {
			w.tag(funcTag)
		} else {
			w.tag(genericFuncTag)
		}
		w.pos(obj.Pos())
		// The tparam list of the function type is the declaration of the type
		// params. So, write out the type params right now. Then those type params
		// will be referenced via their type offset (via typOff) in all other
		// places in the signature and function where they are used.
		//
		// While importing the type parameters, tparamList computes and records
		// their export name, so that it can be later used when writing the index.
		if tparams := sig.TypeParams(); tparams.Len() > 0 {
			w.tparamList(obj.Name(), tparams, obj.Pkg())
		}
		w.signature(sig)

	case *types.Const:
		w.tag(constTag)
		w.pos(obj.Pos())
		w.value(obj.Type(), obj.Val())

	case *types.TypeName:
		t := obj.Type()

		if tparam, ok := types.Unalias(t).(*types.TypeParam); ok {
			w.tag(typeParamTag)
			w.pos(obj.Pos())
			constraint := tparam.Constraint()
			if p.version >= iexportVersionGo1_18 {
				implicit := false
				if iface, _ := types.Unalias(constraint).(*types.Interface); iface != nil {
					implicit = iface.IsImplicit()
				}
				w.bool(implicit)
			}
			w.typ(constraint, obj.Pkg())
			break
		}

		if obj.IsAlias() {
			alias, materialized := t.(*types.Alias) // perhaps false for certain built-ins?

			var tparams *types.TypeParamList
			if materialized {
				tparams = alias.TypeParams()
			}
			if tparams.Len() == 0 {
				w.tag(aliasTag)
			} else {
				w.tag(genericAliasTag)
			}
			w.pos(obj.Pos())
			if tparams.Len() > 0 {
				w.tparamList(obj.Name(), tparams, obj.Pkg())
			}
			if materialized {
				// Preserve materialized aliases,
				// even of non-exported types.
				t = alias.Rhs()
			}
			w.typ(t, obj.Pkg())
			break
		}

		// Defined type.
		named, ok := t.(*types.Named)
		if !ok {
			panic(internalErrorf("%s is not a defined type", t))
		}

		if named.TypeParams().Len() == 0 {
			w.tag(typeTag)
		} else {
			w.tag(genericTypeTag)
		}
		w.pos(obj.Pos())

		if named.TypeParams().Len() > 0 {
			// While importing the type parameters, tparamList computes and records
			// their export name, so that it can be later used when writing the index.
			w.tparamList(obj.Name(), named.TypeParams(), obj.Pkg())
		}

		underlying := named.Underlying()
		w.typ(underlying, obj.Pkg())

		if types.IsInterface(t) {
			break
		}

		n := named.NumMethods()
		w.uint64(uint64(n))
		for i := range n {
			m := named.Method(i)
			w.pos(m.Pos())
			w.string(m.Name())
			sig, _ := m.Type().(*types.Signature)

			// Receiver type parameters are type arguments of the receiver type, so
			// their name must be qualified before exporting recv.
			if rparams := sig.RecvTypeParams(); rparams.Len() > 0 {
				prefix := obj.Name() + "." + m.Name()
				for rparam := range rparams.TypeParams() {
					name := tparamExportName(prefix, rparam)
					w.p.tparamNames[rparam.Obj()] = name
				}
			}
			w.param(sig.Recv())
			w.signature(sig)
		}

	default:
		panic(internalErrorf("unexpected object: %v", obj))
	}

	p.declIndex[obj] = w.flush()
}

func (w *exportWriter) tag(tag byte) {
	w.data.WriteByte(tag)
}

func (w *exportWriter) pos(pos token.Pos) {
	if w.p.shallow {
		w.posV2(pos)
	} else if w.p.version >= iexportVersionPosCol {
		w.posV1(pos)
	} else {
		w.posV0(pos)
	}
}

// posV2 encoding (used only in shallow mode) records positions as
// (file, offset), where file is the index in the token.File table
// (which records the file name and newline offsets) and offset is a
// byte offset. It effectively ignores //line directives.
func (w *exportWriter) posV2(pos token.Pos) {
	if pos == token.NoPos {
		w.uint64(0)
		return
	}
	file := w.p.fset.File(pos) // fset must be non-nil
	index, offset := w.p.fileIndexAndOffset(file, pos)
	w.uint64(1 + index)
	w.uint64(offset)
}

func (w *exportWriter) posV1(pos token.Pos) {
	if w.p.fset == nil {
		w.int64(0)
		return
	}

	p := w.p.fset.Position(pos)
	file := p.Filename
	line := int64(p.Line)
	column := int64(p.Column)

	deltaColumn := (column - w.prevColumn) << 1
	deltaLine := (line - w.prevLine) << 1

	if file != w.prevFile {
		deltaLine |= 1
	}
	if deltaLine != 0 {
		deltaColumn |= 1
	}

	w.int64(deltaColumn)
	if deltaColumn&1 != 0 {
		w.int64(deltaLine)
		if deltaLine&1 != 0 {
			w.string(file)
		}
	}

	w.prevFile = file
	w.prevLine = line
	w.prevColumn = column
}

func (w *exportWriter) posV0(pos token.Pos) {
	if w.p.fset == nil {
		w.int64(0)
		return
	}

	p := w.p.fset.Position(pos)
	file := p.Filename
	line := int64(p.Line)

	// When file is the same as the last position (common case),
	// we can save a few bytes by delta encoding just the line
	// number.
	//
	// Note: Because data objects may be read out of order (or not
	// at all), we can only apply delta encoding within a single
	// object. This is handled implicitly by tracking prevFile and
	// prevLine as fields of exportWriter.

	if file == w.prevFile {
		delta := line - w.prevLine
		w.int64(delta)
		if delta == deltaNewFile {
			w.int64(-1)
		}
	} else {
		w.int64(deltaNewFile)
		w.int64(line) // line >= 0
		w.string(file)
		w.prevFile = file
	}
	w.prevLine = line
}

func (w *exportWriter) pkg(pkg *types.Package) {
	if pkg == nil {
		// [exportWriter.typ] accepts a nil pkg only for types
		// of constants, which cannot contain named objects
		// such as fields or methods and thus should never
		// reach this method (#76222).
		panic("nil package")
	}
	// Ensure any referenced packages are declared in the main index.
	w.p.allPkgs[pkg] = true

	w.string(w.exportPath(pkg))
}

func (w *exportWriter) qualifiedType(obj *types.TypeName) {
	name := w.p.exportName(obj)

	// Ensure any referenced declarations are written out too.
	w.p.pushDecl(obj)
	w.string(name)
	w.pkg(obj.Pkg())
}

// typ emits the specified type.
//
// Objects within the type (struct fields and interface methods) are
// qualified by pkg. It may be nil if the type cannot contain objects,
// such as the type of a constant.
func (w *exportWriter) typ(t types.Type, pkg *types.Package) {
	w.data.uint64(w.p.typOff(t, pkg))
}

func (p *iexporter) newWriter() *exportWriter {
	return &exportWriter{p: p}
}

func (w *exportWriter) flush() uint64 {
	off := uint64(w.p.data0.Len())
	io.Copy(&w.p.data0, &w.data)
	return off
}

func (p *iexporter) typOff(t types.Type, pkg *types.Package) uint64 {
	off, ok := p.typIndex[t]
	if !ok {
		w := p.newWriter()
		w.doTyp(t, pkg)
		off = predeclReserved + w.flush()
		p.typIndex[t] = off
	}
	return off
}

func (w *exportWriter) startType(k itag) {
	w.data.uint64(uint64(k))
}

// doTyp is the implementation of [exportWriter.typ].
func (w *exportWriter) doTyp(t types.Type, pkg *types.Package) {
	if trace {
		w.p.trace("exporting type %s (%T)", t, t)
		w.p.indent++
		defer func() {
			w.p.indent--
			w.p.trace("=> %s", t)
		}()
	}
	switch t := t.(type) {
	case *types.Alias:
		if targs := t.TypeArgs(); targs.Len() > 0 {
			w.startType(instanceType)
			w.pos(t.Obj().Pos())
			w.typeList(targs, pkg)
			w.typ(t.Origin(), pkg)
			return
		}
		w.startType(aliasType)
		w.qualifiedType(t.Obj())

	case *types.Named:
		if targs := t.TypeArgs(); targs.Len() > 0 {
			w.startType(instanceType)
			// TODO(rfindley): investigate if this position is correct, and if it
			// matters.
			w.pos(t.Obj().Pos())
			w.typeList(targs, pkg)
			w.typ(t.Origin(), pkg)
			return
		}
		w.startType(definedType)
		w.qualifiedType(t.Obj())

	case *types.TypeParam:
		w.startType(typeParamType)
		w.qualifiedType(t.Obj())

	case *types.Pointer:
		w.startType(pointerType)
		w.typ(t.Elem(), pkg)

	case *types.Slice:
		w.startType(sliceType)
		w.typ(t.Elem(), pkg)

	case *types.Array:
		w.startType(arrayType)
		w.uint64(uint64(t.Len()))
		w.typ(t.Elem(), pkg)

	case *types.Chan:
		w.startType(chanType)
		// 1 RecvOnly; 2 SendOnly; 3 SendRecv
		var dir uint64
		switch t.Dir() {
		case types.RecvOnly:
			dir = 1
		case types.SendOnly:
			dir = 2
		case types.SendRecv:
			dir = 3
		}
		w.uint64(dir)
		w.typ(t.Elem(), pkg)

	case *types.Map:
		w.startType(mapType)
		w.typ(t.Key(), pkg)
		w.typ(t.Elem(), pkg)

	case *types.Signature:
		w.startType(signatureType)
		w.pkg(pkg) // qualifies param/result vars
		w.signature(t)

	case *types.Struct:
		w.startType(structType)
		n := t.NumFields()
		// Even for struct{} we must emit some qualifying package, because that's
		// what the compiler does, and thus that's what the importer expects.
		fieldPkg := pkg
		if n > 0 {
			fieldPkg = t.Field(0).Pkg()
		}
		if fieldPkg == nil {
			// TODO(rfindley): improve this very hacky logic.
			//
			// The importer expects a package to be set for all struct types, even
			// those with no fields. A better encoding might be to set NumFields
			// before pkg. setPkg panics with a nil package, which may be possible
			// to reach with invalid packages (and perhaps valid packages, too?), so
			// (arbitrarily) set the localpkg if available.
			//
			// Alternatively, we may be able to simply guarantee that pkg != nil, by
			// reconsidering the encoding of constant values.
			if w.p.shallow {
				fieldPkg = w.p.localpkg
			} else {
				panic(internalErrorf("no package to set for empty struct"))
			}
		}
		w.pkg(fieldPkg)
		w.uint64(uint64(n))

		for i := range n {
			f := t.Field(i)
			if w.p.shallow {
				w.objectPath(f)
			}
			w.pos(f.Pos())
			w.string(f.Name()) // unexported fields implicitly qualified by prior setPkg
			w.typ(f.Type(), fieldPkg)
			w.bool(f.Anonymous())
			w.string(t.Tag(i)) // note (or tag)
		}

	case *types.Interface:
		w.startType(interfaceType)
		w.pkg(pkg) // qualifies unexported method funcs

		n := t.NumEmbeddeds()
		w.uint64(uint64(n))
		for i := 0; i < n; i++ {
			ft := t.EmbeddedType(i)
			if named, _ := types.Unalias(ft).(*types.Named); named != nil {
				w.pos(named.Obj().Pos())
			} else {
				// e.g. ~int
				w.pos(token.NoPos)
			}
			w.typ(ft, pkg)
		}

		// See comment for struct fields. In shallow mode we change the encoding
		// for interface methods that are promoted from other packages.

		n = t.NumExplicitMethods()
		w.uint64(uint64(n))
		for i := 0; i < n; i++ {
			m := t.ExplicitMethod(i)
			if w.p.shallow {
				w.objectPath(m)
			}
			w.pos(m.Pos())
			w.string(m.Name())
			sig, _ := m.Type().(*types.Signature)
			w.signature(sig)
		}

	case *types.Union:
		w.startType(unionType)
		nt := t.Len()
		w.uint64(uint64(nt))
		for i := range nt {
			term := t.Term(i)
			w.bool(term.Tilde())
			w.typ(term.Type(), pkg)
		}

	default:
		panic(internalErrorf("unexpected type: %v, %v", t, reflect.TypeOf(t)))
	}
}

// objectPath writes the package and objectPath to use to look up obj in a
// different package, when encoding in "shallow" mode.
//
// When doing a shallow import, the importer creates only the local package,
// and requests package symbols for dependencies from the client.
// However, certain types defined in the local package may hold objects defined
// (perhaps deeply) within another package.
//
// For example, consider the following:
//
//	package a
//	func F() chan * map[string] struct { X int }
//
//	package b
//	import "a"
//	var B = a.F()
//
// In this example, the type of b.B holds fields defined in package a.
// In order to have the correct canonical objects for the field defined in the
// type of B, they are encoded as objectPaths and later looked up in the
// importer. The same problem applies to interface methods.
func (w *exportWriter) objectPath(obj types.Object) {
	if obj.Pkg() == nil || obj.Pkg() == w.p.localpkg {
		// obj.Pkg() may be nil for the builtin error.Error.
		// In this case, or if obj is declared in the local package, no need to
		// encode.
		w.string("")
		return
	}
	objectPath, err := w.p.objectpathEncoder().For(obj)
	if err != nil {
		// Fall back to the empty string, which will cause the importer to create a
		// new object, which matches earlier behavior. Creating a new object is
		// sufficient for many purposes (such as type checking), but causes certain
		// references algorithms to fail (golang/go#60819). However, we didn't
		// notice this problem during months of gopls@v0.12.0 testing.
		//
		// TODO(golang/go#61674): this workaround is insufficient, as in the case
		// where the field forwarded from an instantiated type that may not appear
		// in the export data of the original package:
		//
		//  // package a
		//  type A[P any] struct{ F P }
		//
		//  // package b
		//  type B a.A[int]
		//
		// We need to update references algorithms not to depend on this
		// de-duplication, at which point we may want to simply remove the
		// workaround here.
		w.string("")
		return
	}
	w.string(string(objectPath))
	w.pkg(obj.Pkg())
}

func (w *exportWriter) signature(sig *types.Signature) {
	w.paramList(sig.Params())
	w.paramList(sig.Results())
	if sig.Params().Len() > 0 {
		w.bool(sig.Variadic())
	}
}

func (w *exportWriter) typeList(ts *types.TypeList, pkg *types.Package) {
	w.uint64(uint64(ts.Len()))
	for t := range ts.Types() {
		w.typ(t, pkg)
	}
}

func (w *exportWriter) tparamList(prefix string, list *types.TypeParamList, pkg *types.Package) {
	ll := uint64(list.Len())
	w.uint64(ll)
	for tparam := range list.TypeParams() {
		// Set the type parameter exportName before exporting its type.
		exportName := tparamExportName(prefix, tparam)
		w.p.tparamNames[tparam.Obj()] = exportName
		w.typ(tparam, pkg)
	}
}

const blankMarker = "$"

// tparamExportName returns the 'exported' name of a type parameter, which
// differs from its actual object name: it is prefixed with a qualifier, and
// blank type parameter names are disambiguated by their index in the type
// parameter list.
func tparamExportName(prefix string, tparam *types.TypeParam) string {
	assert(prefix != "")
	name := tparam.Obj().Name()
	if name == "_" {
		name = blankMarker + strconv.Itoa(tparam.Index())
	}
	return prefix + "." + name
}

// tparamName returns the real name of a type parameter, after stripping its
// qualifying prefix and reverting blank-name encoding. See tparamExportName
// for details.
func tparamName(exportName string) string {
	// Remove the "path" from the type param name that makes it unique.
	ix := strings.LastIndex(exportName, ".")
	if ix < 0 {
		errorf("malformed type parameter export name %s: missing prefix", exportName)
	}
	name := exportName[ix+1:]
	if strings.HasPrefix(name, blankMarker) {
		return "_"
	}
	return name
}

func (w *exportWriter) paramList(tup *types.Tuple) {
	n := tup.Len()
	w.uint64(uint64(n))
	for i := range n {
		w.param(tup.At(i))
	}
}

func (w *exportWriter) param(obj types.Object) {
	w.pos(obj.Pos())
	w.localIdent(obj)
	w.typ(obj.Type(), obj.Pkg())
}

func (w *exportWriter) value(typ types.Type, v constant.Value) {
	w.typ(typ, nil)
	if w.p.version >= iexportVersionGo1_18 {
		w.int64(int64(v.Kind()))
	}

	if v.Kind() == constant.Unknown {
		// golang/go#60605: treat unknown constant values as if they have invalid type
		//
		// This loses some fidelity over the package type-checked from source, but that
		// is acceptable.
		//
		// TODO(rfindley): we should switch on the recorded constant kind rather
		// than the constant type
		return
	}

	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
	case types.IsBoolean:
		w.bool(constant.BoolVal(v))
	case types.IsInteger:
		var i big.Int
		if i64, exact := constant.Int64Val(v); exact {
			i.SetInt64(i64)
		} else if ui64, exact := constant.Uint64Val(v); exact {
			i.SetUint64(ui64)
		} else {
			i.SetString(v.ExactString(), 10)
		}
		w.mpint(&i, typ)
	case types.IsFloat:
		f := constantToFloat(v)
		w.mpfloat(f, typ)
	case types.IsComplex:
		w.mpfloat(constantToFloat(constant.Real(v)), typ)
		w.mpfloat(constantToFloat(constant.Imag(v)), typ)
	case types.IsString:
		w.string(constant.StringVal(v))
	default:
		if b.Kind() == types.Invalid {
			// package contains type errors
			break
		}
		panic(internalErrorf("unexpected type %v (%v)", typ, typ.Underlying()))
	}
}

// constantToFloat converts a constant.Value with kind constant.Float to a
// big.Float.
func constantToFloat(x constant.Value) *big.Float {
	x = constant.ToFloat(x)
	// Use the same floating-point precision (512) as cmd/compile
	// (see Mpprec in cmd/compile/internal/gc/mpfloat.go).
	const mpprec = 512
	var f big.Float
	f.SetPrec(mpprec)
	if v, exact := constant.Float64Val(x); exact {
		// float64
		f.SetFloat64(v)
	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
		// TODO(gri): add big.Rat accessor to constant.Value.
		n := valueToRat(num)
		d := valueToRat(denom)
		f.SetRat(n.Quo(n, d))
	} else {
		// Value too large to represent as a fraction => inaccessible.
		// TODO(gri): add big.Float accessor to constant.Value.
		_, ok := f.SetString(x.ExactString())
		assert(ok)
	}
	return &f
}

func valueToRat(x constant.Value) *big.Rat {
	// Convert little-endian to big-endian.
	// I can't believe this is necessary.
	bytes := constant.Bytes(x)
	for i := 0; i < len(bytes)/2; i++ {
		bytes[i], bytes[len(bytes)-1-i] = bytes[len(bytes)-1-i], bytes[i]
	}
	return new(big.Rat).SetInt(new(big.Int).SetBytes(bytes))
}

// mpint exports a multi-precision integer.
//
// For unsigned types, small values are written out as a single
// byte. Larger values are written out as a length-prefixed big-endian
// byte string, where the length prefix is encoded as its complement.
// For example, bytes 0, 1, and 2 directly represent the integer
// values 0, 1, and 2; while bytes 255, 254, and 253 indicate a 1-,
// 2-, and 3-byte big-endian string follow.
//
// Encoding for signed types use the same general approach as for
// unsigned types, except small values use zig-zag encoding and the
// bottom bit of length prefix byte for large values is reserved as a
// sign bit.
//
// The exact boundary between small and large encodings varies
// according to the maximum number of bytes needed to encode a value
// of type typ. As a special case, 8-bit types are always encoded as a
// single byte.
//
// TODO(mdempsky): Is this level of complexity really worthwhile?
func (w *exportWriter) mpint(x *big.Int, typ types.Type) {
	basic, ok := typ.Underlying().(*types.Basic)
	if !ok {
		panic(internalErrorf("unexpected type %v (%T)", typ.Underlying(), typ.Underlying()))
	}

	signed, maxBytes := intSize(basic)

	negative := x.Sign() < 0
	if !signed && negative {
		panic(internalErrorf("negative unsigned integer; type %v, value %v", typ, x))
	}

	b := x.Bytes()
	if len(b) > 0 && b[0] == 0 {
		panic(internalErrorf("leading zeros"))
	}
	if uint(len(b)) > maxBytes {
		panic(internalErrorf("bad mpint length: %d > %d (type %v, value %v)", len(b), maxBytes, typ, x))
	}

	maxSmall := 256 - maxBytes
	if signed {
		maxSmall = 256 - 2*maxBytes
	}
	if maxBytes == 1 {
		maxSmall = 256
	}

	// Check if x can use small value encoding.
	if len(b) <= 1 {
		var ux uint
		if len(b) == 1 {
			ux = uint(b[0])
		}
		if signed {
			ux <<= 1
			if negative {
				ux--
			}
		}
		if ux < maxSmall {
			w.data.WriteByte(byte(ux))
			return
		}
	}

	n := 256 - uint(len(b))
	if signed {
		n = 256 - 2*uint(len(b))
		if negative {
			n |= 1
		}
	}
	if n < maxSmall || n >= 256 {
		panic(internalErrorf("encoding mistake: %d, %v, %v => %d", len(b), signed, negative, n))
	}

	w.data.WriteByte(byte(n))
	w.data.Write(b)
}

// mpfloat exports a multi-precision floating point number.
//
// The number's value is decomposed into mantissa × 2**exponent, where
// mantissa is an integer. The value is written out as mantissa (as a
// multi-precision integer) and then the exponent, except exponent is
// omitted if mantissa is zero.
func (w *exportWriter) mpfloat(f *big.Float, typ types.Type) {
	if f.IsInf() {
		panic("infinite constant")
	}

	// Break into f = mant × 2**exp, with 0.5 <= mant < 1.
	var mant big.Float
	exp := int64(f.MantExp(&mant))

	// Scale so that mant is an integer.
	prec := mant.MinPrec()
	mant.SetMantExp(&mant, int(prec))
	exp -= int64(prec)

	manti, acc := mant.Int(nil)
	if acc != big.Exact {
		panic(internalErrorf("mantissa scaling failed for %f (%s)", f, acc))
	}
	w.mpint(manti, typ)
	if manti.Sign() != 0 {
		w.int64(exp)
	}
}

func (w *exportWriter) bool(b bool) bool {
	var x uint64
	if b {
		x = 1
	}
	w.uint64(x)
	return b
}

func (w *exportWriter) int64(x int64)   { w.data.int64(x) }
func (w *exportWriter) uint64(x uint64) { w.data.uint64(x) }
func (w *exportWriter) string(s string) { w.uint64(w.p.stringOff(s)) }

func (w *exportWriter) localIdent(obj types.Object) {
	// Anonymous parameters.
	if obj == nil {
		w.string("")
		return
	}

	name := obj.Name()
	if name == "_" {
		w.string("_")
		return
	}

	w.string(name)
}

type intWriter struct {
	bytes.Buffer
}

func (w *intWriter) int64(x int64) {
	var buf [binary.MaxVarintLen64]byte
	n := binary.PutVarint(buf[:], x)
	w.Write(buf[:n])
}

func (w *intWriter) uint64(x uint64) {
	var buf [binary.MaxVarintLen64]byte
	n := binary.PutUvarint(buf[:], x)
	w.Write(buf[:n])
}

func assert(cond bool) {
	if !cond {
		panic("internal error: assertion failed")
	}
}

// The below is copied from go/src/cmd/compile/internal/gc/syntax.go.

// objQueue is a FIFO queue of types.Object. The zero value of objQueue is
// a ready-to-use empty queue.
type objQueue struct {
	ring       []types.Object
	head, tail int
}

// empty returns true if q contains no Nodes.
func (q *objQueue) empty() bool {
	return q.head == q.tail
}

// pushTail appends n to the tail of the queue.
func (q *objQueue) pushTail(obj types.Object) {
	if len(q.ring) == 0 {
		q.ring = make([]types.Object, 16)
	} else if q.head+len(q.ring) == q.tail {
		// Grow the ring.
		nring := make([]types.Object, len(q.ring)*2)
		// Copy the old elements.
		part := q.ring[q.head%len(q.ring):]
		if q.tail-q.head <= len(part) {
			part = part[:q.tail-q.head]
			copy(nring, part)
		} else {
			pos := copy(nring, part)
			copy(nring[pos:], q.ring[:q.tail%len(q.ring)])
		}
		q.ring, q.head, q.tail = nring, 0, q.tail-q.head
	}

	q.ring[q.tail%len(q.ring)] = obj
	q.tail++
}

// popHead pops a node from the head of the queue. It panics if q is empty.
func (q *objQueue) popHead() types.Object {
	if q.empty() {
		panic("dequeue empty")
	}
	obj := q.ring[q.head%len(q.ring)]
	q.head++
	return obj
}

// internalError represents an error generated inside this package.
type internalError string

func (e internalError) Error() string { return "gcimporter: " + string(e) }

// TODO(adonovan): make this call panic, so that it's symmetric with errorf.
// Otherwise it's easy to forget to do anything with the error.
//
// TODO(adonovan): also, consider switching the names "errorf" and
// "internalErrorf" as the former is used for bugs, whose cause is
// internal inconsistency, whereas the latter is used for ordinary
// situations like bad input, whose cause is external.
func internalErrorf(format string, args ...any) error {
	return internalError(fmt.Sprintf(format, args...))
}


================================================
FILE: internal/gcimporter/iexport_common_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter

// Temporarily expose version-related functionality so that we can test at
// specific export data versions.

var IExportCommon = iexportCommon

const IExportVersion = iexportVersionGenerics


================================================
FILE: internal/gcimporter/iexport_go118_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter_test

// This file defines test of generics features introduce in go1.18.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/internal/gcimporter"
	"golang.org/x/tools/internal/testenv"
)

// TODO(rfindley): migrate this to testdata, as has been done in the standard library.
func TestGenericExport(t *testing.T) {
	const src = `
package generic

type Any any

type T[A, B any] struct { Left A; Right B }

func (T[P, Q]) m() {}

var X T[int, string] = T[int, string]{1, "hi"}

func ToInt[P interface{ ~int }](p P) int { return int(p) }

var IntID = ToInt[int]

type G[C comparable] int

func ImplicitFunc[T ~int]() {}

type ImplicitType[T ~int] int

// Exercise constant import/export
const C1 = 42
const C2 int = 42
const C3 float64 = 42

type Constraint[T any] interface {
       m(T)
}

// TODO(rfindley): revert to multiple blanks once the restriction on multiple
// blanks is removed from the type checker.
// type Blanks[_ any, _ Constraint[int]] int
// func (Blanks[_, _]) m() {}
type Blanks[_ any] int
func (Blanks[_]) m() {}
`
	testExportSrc(t, []byte(src))
}

func testExportSrc(t *testing.T, src []byte) {
	// This package only handles gc export data.
	if runtime.Compiler != "gc" {
		t.Skipf("gc-built packages not available (compiler = %s)", runtime.Compiler)
	}
	testenv.NeedsGoBuild(t)

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "g.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	conf := types.Config{
		Importer: importer.Default(),
	}
	pkg, err := conf.Check("", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// export
	version := gcimporter.IExportVersion
	data, err := iexport(fset, version, pkg)
	if err != nil {
		t.Fatal(err)
	}

	testPkgData(t, fset, version, pkg, data)
}

func TestIndexedImportTypeparamTests(t *testing.T) {
	testenv.NeedsGoBuild(t) // to find stdlib export data in the build cache
	testenv.NeedsGOROOTDir(t, "test")

	// Check go files in test/typeparam.
	rootDir := filepath.Join(runtime.GOROOT(), "test", "typeparam")
	list, err := os.ReadDir(rootDir)
	if err != nil {
		t.Fatal(err)
	}

	for _, entry := range list {
		if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".go") {
			// For now, only consider standalone go files.
			continue
		}

		t.Run(entry.Name(), func(t *testing.T) {
			filename := filepath.Join(rootDir, entry.Name())
			src, err := os.ReadFile(filename)
			if err != nil {
				t.Fatal(err)
			}

			if !bytes.HasPrefix(src, []byte("// run")) && !bytes.HasPrefix(src, []byte("// compile")) {
				// We're bypassing the logic of run.go here, so be conservative about
				// the files we consider in an attempt to make this test more robust to
				// changes in test/typeparams.
				t.Skipf("not detected as a run test")
			}

			testExportSrc(t, src)
		})
	}
}

func TestRecursiveExport_Issue51219(t *testing.T) {
	const srca = `
package a

type Interaction[DataT InteractionDataConstraint] struct {
}

type InteractionDataConstraint interface {
	[]byte |
		UserCommandInteractionData
}

type UserCommandInteractionData struct {
	resolvedInteractionWithOptions
}

type resolvedInteractionWithOptions struct {
	Resolved Resolved
}

type Resolved struct {
	Users ResolvedData[User]
}

type ResolvedData[T ResolvedDataConstraint] map[uint64]T

type ResolvedDataConstraint interface {
	User | Message
}

type User struct{}

type Message struct {
	Interaction *Interaction[[]byte]
}
`

	const srcb = `
package b

import (
	"a"
)

// InteractionRequest is an incoming request Interaction
type InteractionRequest[T a.InteractionDataConstraint] struct {
	a.Interaction[T]
}
`

	const srcp = `
package p

import (
	"b"
)

// ResponseWriterMock mocks corde's ResponseWriter interface
type ResponseWriterMock struct {
	x b.InteractionRequest[[]byte]
}
`

	importer := &testImporter{
		src: map[string][]byte{
			"a": []byte(srca),
			"b": []byte(srcb),
			"p": []byte(srcp),
		},
		pkgs: make(map[string]*types.Package),
	}
	_, err := importer.Import("p")
	if err != nil {
		t.Fatal(err)
	}
}

// testImporter is a helper to test chains of imports using export data.
type testImporter struct {
	src  map[string][]byte         // original source
	pkgs map[string]*types.Package // memoized imported packages
}

func (t *testImporter) Import(path string) (*types.Package, error) {
	if pkg, ok := t.pkgs[path]; ok {
		return pkg, nil
	}
	src, ok := t.src[path]
	if !ok {
		return nil, fmt.Errorf("unknown path %v", path)
	}

	// Type-check, but don't return this package directly.
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, path+".go", src, 0)
	if err != nil {
		return nil, err
	}
	conf := types.Config{
		Importer: t,
	}
	pkg, err := conf.Check(path, fset, []*ast.File{f}, nil)
	if err != nil {
		return nil, err
	}

	// Export and import to get the package imported from export data.
	exportdata, err := iexport(fset, gcimporter.IExportVersion, pkg)
	if err != nil {
		return nil, err
	}
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg.Path())
	if err != nil {
		return nil, err
	}
	t.pkgs[path] = pkg2
	return pkg2, nil
}


================================================
FILE: internal/gcimporter/iexport_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is a copy of bexport_test.go for iexport.go.

package gcimporter_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/constant"
	"go/parser"
	"go/token"
	"go/types"
	"math/big"
	"path/filepath"
	"reflect"
	"strings"
	"testing"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/gcimporter"
	"golang.org/x/tools/internal/testenv"
)

func iexport(fset *token.FileSet, version int, pkg *types.Package) ([]byte, error) {
	var buf bytes.Buffer
	const bundle, shallow = false, false
	if err := gcimporter.IExportCommon(&buf, fset, bundle, shallow, version, []*types.Package{pkg}, nil); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

func TestIExportData_stdlib(t *testing.T) {
	testenv.NeedsGoPackages(t)
	if isRace {
		t.Skipf("stdlib tests take too long in race mode and flake on builders")
	}
	if testing.Short() {
		t.Skip("skipping RAM hungry test in -short mode")
	}

	var errorsDir string // GOROOT/src/errors directory
	{
		cfg := packages.Config{
			Mode: packages.NeedName | packages.NeedFiles,
		}
		pkgs, err := packages.Load(&cfg, "errors")
		if err != nil {
			t.Fatal(err)
		}
		errorsDir = filepath.Dir(pkgs[0].GoFiles[0])
	}

	// Load types from syntax for all std packages.
	//
	// Append a file to package errors containing type and
	// value errors to ensure they are properly encoded/decoded.
	const bad = `package errors
const UnknownValue = "" + 0
type UnknownType undefined
`
	cfg := packages.Config{
		Mode:    packages.LoadAllSyntax | packages.NeedDeps,
		Overlay: map[string][]byte{filepath.Join(errorsDir, "bad.go"): []byte(bad)},
	}
	pkgs, err := packages.Load(&cfg, "std") // ~800ms
	if err != nil {
		t.Fatal(err)
	}
	fset := pkgs[0].Fset

	version := gcimporter.IExportVersion

	// Export and reimport each package, and check that they match.
	var allPkgs []*types.Package
	var errorsPkg *types.Package                             // reimported errors package
	packages.Visit(pkgs, nil, func(ppkg *packages.Package) { // ~300ms
		pkg := ppkg.Types
		path := pkg.Path()
		if path == "unsafe" ||
			strings.HasPrefix(path, "cmd/") ||
			strings.HasPrefix(path, "vendor/") {
			return
		}
		allPkgs = append(allPkgs, pkg)

		// Export and reimport the package, and compare.
		exportdata, err := iexport(fset, version, pkg)
		if err != nil {
			t.Error(err)
			return
		}
		pkg2 := testPkgData(t, fset, version, pkg, exportdata)
		if path == "errors" {
			errorsPkg = pkg2
		}
	})

	// Assert that we saw a plausible sized library.
	const minStdlibPackages = 248
	if n := len(allPkgs); n < minStdlibPackages {
		t.Errorf("Loaded only %d packages, want at least %d", n, minStdlibPackages)
	}

	// Check that reimported errors package has bad decls.
	if errorsPkg == nil {
		t.Fatalf("'errors' package not found")
	}
	for _, name := range []string{"UnknownType", "UnknownValue"} {
		obj := errorsPkg.Scope().Lookup(name)
		if obj == nil {
			t.Errorf("errors.%s not found", name)
		}
		if typ := obj.Type().Underlying(); typ.String() != "invalid type" {
			t.Errorf("errors.%s has underlying type %s, want invalid type", name, typ)
		}
	}

	// (Sole) test of bundle functionality (250ms).
	var bundle bytes.Buffer
	if err := gcimporter.IExportBundle(&bundle, fset, allPkgs); err != nil {
		t.Fatal(err)
	}
	fset2 := token.NewFileSet()
	imports := make(map[string]*types.Package)
	pkgs2, err := gcimporter.IImportBundle(fset2, imports, bundle.Bytes())
	if err != nil {
		t.Fatal(err)
	}
	for i, pkg := range allPkgs {
		testPkg(t, fset, version, pkg, fset2, pkgs2[i])
	}
}

// testPkgData imports a package from export data and compares it with pkg.
func testPkgData(t *testing.T, fset *token.FileSet, version int, pkg *types.Package, exportdata []byte) *types.Package {
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg.Path())
	if err != nil {
		t.Errorf("IImportData(%s): %v", pkg.Path(), err)
	}

	testPkg(t, fset, version, pkg, fset2, pkg2)
	return pkg2
}

func testPkg(t *testing.T, fset *token.FileSet, version int, pkg *types.Package, fset2 *token.FileSet, pkg2 *types.Package) {
	if _, err := iexport(fset2, version, pkg2); err != nil {
		t.Errorf("reexport %q: %v", pkg.Path(), err)
	}

	// Compare the packages' corresponding members.
	for _, name := range pkg.Scope().Names() {
		if !token.IsExported(name) {
			continue
		}
		obj1 := pkg.Scope().Lookup(name)
		obj2 := pkg2.Scope().Lookup(name)
		if obj2 == nil {
			t.Errorf("%s.%s not found, want %s", pkg.Path(), name, obj1)
			continue
		}

		fl1 := fileLine(fset, obj1)
		fl2 := fileLine(fset2, obj2)
		if fl1 != fl2 {
			t.Errorf("%s.%s: got posn %s, want %s",
				pkg.Path(), name, fl2, fl1)
		}

		if err := cmpObj(obj1, obj2); err != nil {
			t.Errorf("%s.%s: %s\ngot:  %s\nwant: %s",
				pkg.Path(), name, err, obj2, obj1)
		}
	}
}

// TestIExportData_long tests the position of an import object declared in
// a very long input file.  Line numbers greater than maxlines are
// reported as line 1, not garbage or token.NoPos.
func TestIExportData_long(t *testing.T) {
	// parse and typecheck
	longFile := "package foo" + strings.Repeat("\n", 123456) + "var X int"
	fset1 := token.NewFileSet()
	f, err := parser.ParseFile(fset1, "foo.go", longFile, 0)
	if err != nil {
		t.Fatal(err)
	}
	var conf types.Config
	pkg, err := conf.Check("foo", fset1, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// export
	exportdata, err := iexport(fset1, gcimporter.IExportVersion, pkg)
	if err != nil {
		t.Fatal(err)
	}

	// import
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg.Path())
	if err != nil {
		t.Fatalf("IImportData(%s): %v", pkg.Path(), err)
	}

	// compare
	posn1 := fset1.Position(pkg.Scope().Lookup("X").Pos())
	posn2 := fset2.Position(pkg2.Scope().Lookup("X").Pos())
	if want := "foo.go:1:1"; posn2.String() != want {
		t.Errorf("X position = %s, want %s (orig was %s)",
			posn2, want, posn1)
	}
}

func TestIExportData_typealiases(t *testing.T) {
	// parse and typecheck
	fset1 := token.NewFileSet()
	f, err := parser.ParseFile(fset1, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	var conf types.Config
	pkg1, err := conf.Check("p", fset1, []*ast.File{f}, nil)
	if err == nil {
		// foo in undeclared in src; we should see an error
		t.Fatal("invalid source type-checked without error")
	}
	if pkg1 == nil {
		// despite incorrect src we should see a (partially) type-checked package
		t.Fatal("nil package returned")
	}
	checkPkg(t, pkg1, "export")

	// export
	// use a nil fileset here to confirm that it doesn't panic
	exportdata, err := iexport(nil, gcimporter.IExportVersion, pkg1)
	if err != nil {
		t.Fatal(err)
	}

	// import
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg1.Path())
	if err != nil {
		t.Fatalf("IImportData(%s): %v", pkg1.Path(), err)
	}
	checkPkg(t, pkg2, "import")
}

// cmpObj reports how x and y differ. They are assumed to belong to different
// universes so cannot be compared directly. It is an adapted version of
// equalObj in bexport_test.go.
func cmpObj(x, y types.Object) error {
	if reflect.TypeOf(x) != reflect.TypeOf(y) {
		return fmt.Errorf("%T vs %T", x, y)
	}
	xt := x.Type()
	yt := y.Type()
	switch x := x.(type) {
	case *types.Var, *types.Func:
		// ok
	case *types.Const:
		xval := x.Val()
		yval := y.(*types.Const).Val()
		equal := constant.Compare(xval, token.EQL, yval)
		if !equal {
			// try approx. comparison
			xkind := xval.Kind()
			ykind := yval.Kind()
			if xkind == constant.Complex || ykind == constant.Complex {
				equal = same(constant.Real(xval), constant.Real(yval)) &&
					same(constant.Imag(xval), constant.Imag(yval))
			} else if xkind == constant.Float || ykind == constant.Float {
				equal = same(xval, yval)
			} else if xkind == constant.Unknown && ykind == constant.Unknown {
				equal = true
			}
		}
		if !equal {
			return fmt.Errorf("unequal constants %s vs %s", xval, yval)
		}
	case *types.TypeName:
		if xalias, yalias := x.IsAlias(), y.(*types.TypeName).IsAlias(); xalias != yalias {
			return fmt.Errorf("mismatching IsAlias(): %s vs %s", x, y)
		}

		// equalType does not recurse into the underlying types of named types, so
		// we must pass the underlying type explicitly here. However, in doing this
		// we may skip checking the features of the named types themselves, in
		// situations where the type name is not referenced by the underlying or
		// any other top-level declarations. Therefore, we must explicitly compare
		// named types here, before passing their underlying types into equalType.
		xn, _ := types.Unalias(xt).(*types.Named)
		yn, _ := types.Unalias(yt).(*types.Named)
		if (xn == nil) != (yn == nil) {
			return fmt.Errorf("mismatching types: %T vs %T", xt, yt)
		}
		if xn != nil {
			if err := cmpNamed(xn, yn); err != nil {
				return err
			}
		}
		xt = xt.Underlying()
		yt = yt.Underlying()
	default:
		return fmt.Errorf("unexpected %T", x)
	}
	return equalType(xt, yt)
}

// Use the same floating-point precision (512) as cmd/compile
// (see Mpprec in cmd/compile/internal/gc/mpfloat.go).
const mpprec = 512

// same compares non-complex numeric values and reports if they are approximately equal.
func same(x, y constant.Value) bool {
	xf := constantToFloat(x)
	yf := constantToFloat(y)
	d := new(big.Float).Sub(xf, yf)
	d.Abs(d)
	eps := big.NewFloat(1.0 / (1 << (mpprec - 1))) // allow for 1 bit of error
	return d.Cmp(eps) < 0
}

// copy of the function with the same name in iexport.go.
func constantToFloat(x constant.Value) *big.Float {
	var f big.Float
	f.SetPrec(mpprec)
	if v, exact := constant.Float64Val(x); exact {
		// float64
		f.SetFloat64(v)
	} else if num, denom := constant.Num(x), constant.Denom(x); num.Kind() == constant.Int {
		// TODO(gri): add big.Rat accessor to constant.Value.
		n := valueToRat(num)
		d := valueToRat(denom)
		f.SetRat(n.Quo(n, d))
	} else {
		// Value too large to represent as a fraction => inaccessible.
		// TODO(gri): add big.Float accessor to constant.Value.
		_, ok := f.SetString(x.ExactString())
		if !ok {
			panic("should not reach here")
		}
	}
	return &f
}

// copy of the function with the same name in iexport.go.
func valueToRat(x constant.Value) *big.Rat {
	// Convert little-endian to big-endian.
	// I can't believe this is necessary.
	bytes := constant.Bytes(x)
	for i := 0; i < len(bytes)/2; i++ {
		bytes[i], bytes[len(bytes)-1-i] = bytes[len(bytes)-1-i], bytes[i]
	}
	return new(big.Rat).SetInt(new(big.Int).SetBytes(bytes))
}

// This is a regression test for a bug in iexport of types.Struct:
// unexported fields were losing their implicit package qualifier.
func TestUnexportedStructFields(t *testing.T) {
	fset := token.NewFileSet()
	export := make(map[string][]byte)

	// process parses and type-checks a single-file
	// package and saves its export data.
	process := func(path, content string) {
		syntax, err := parser.ParseFile(fset, path+"/x.go", content, 0)
		if err != nil {
			t.Fatal(err)
		}
		packages := make(map[string]*types.Package) // keys are package paths
		cfg := &types.Config{
			Importer: importerFunc(func(path string) (*types.Package, error) {
				data, ok := export[path]
				if !ok {
					return nil, fmt.Errorf("missing export data for %s", path)
				}
				return gcexportdata.Read(bytes.NewReader(data), fset, packages, path)
			}),
		}
		pkg := types.NewPackage(path, syntax.Name.Name)
		check := types.NewChecker(cfg, fset, pkg, nil)
		if err := check.Files([]*ast.File{syntax}); err != nil {
			t.Fatal(err)
		}
		var out bytes.Buffer
		if err := gcexportdata.Write(&out, fset, pkg); err != nil {
			t.Fatal(err)
		}
		export[path] = out.Bytes()
	}

	// Historically this led to a spurious error:
	// "cannot convert a.M (variable of type a.MyTime) to type time.Time"
	// because the private fields of Time and MyTime were not identical.
	process("time", `package time; type Time struct { x, y int }`)
	process("a", `package a; import "time"; type MyTime time.Time; var M MyTime`)
	process("b", `package b; import ("a"; "time"); var _ = time.Time(a.M)`)
}

type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) { return f(path) }

// TestIExportDataTypeParameterizedAliases tests IExportData
// on both declarations and uses of type parameterized aliases.
func TestIExportDataTypeParameterizedAliases(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)
	skipWindows(t)
	if testenv.Go1Point() == 23 {
		testenv.NeedsGoExperiment(t, "aliastypeparams") // testenv.Go1Point() >= 24 implies aliastypeparams=1
	}

	// High level steps:
	// * parse  and typecheck
	// * export the data for the importer (via IExportData),
	// * import the data (via either x/tools or GOROOT's gcimporter), and
	// * check the imported types.

	const src = `package pkg

type A[T any] = *T
type B[R any, S *R] = []S
type C[U any] = B[U, A[U]]

type Named int
type Chained = C[Named] // B[Named, A[Named]] = B[Named, *Named] = []*Named
`

	// parse and typecheck
	fset1 := token.NewFileSet()
	f, err := parser.ParseFile(fset1, "pkg", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	var conf types.Config
	pkg1, err := conf.Check("pkg", fset1, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	// Read the result of IExportData through x/tools/internal/gcimporter.IImportData.
	// export
	exportdata, err := iexport(fset1, gcimporter.IExportVersion, pkg1)
	if err != nil {
		t.Fatal(err)
	}

	// import
	imports := make(map[string]*types.Package)
	fset2 := token.NewFileSet()
	_, pkg2, err := gcimporter.IImportData(fset2, imports, exportdata, pkg1.Path())
	if err != nil {
		t.Fatalf("IImportData(%s): %v", pkg1.Path(), err)
	}

	pkg := pkg2
	for name, want := range map[string]string{
		"A":       "type pkg.A[T any] = *T",
		"B":       "type pkg.B[R any, S *R] = []S",
		"C":       "type pkg.C[U any] = pkg.B[U, pkg.A[U]]",
		"Named":   "type pkg.Named int",
		"Chained": "type pkg.Chained = pkg.C[pkg.Named]",
	} {
		obj := pkg.Scope().Lookup(name)
		if obj == nil {
			t.Errorf("failed to find %q in package %s", name, pkg)
			continue
		}

		got := strings.ReplaceAll(obj.String(), pkg.Path(), "pkg")
		if got != want {
			t.Errorf("(%q).String()=%q. wanted %q", name, got, want)
		}
	}
}


================================================
FILE: internal/gcimporter/iimport.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Indexed package import.
// See iexport.go for the export data format.

package gcimporter

import (
	"bytes"
	"encoding/binary"
	"fmt"
	"go/constant"
	"go/token"
	"go/types"
	"io"
	"math/big"
	"slices"
	"sort"
	"strings"

	"golang.org/x/tools/go/types/objectpath"
	"golang.org/x/tools/internal/aliases"
	"golang.org/x/tools/internal/typesinternal"
)

type intReader struct {
	*bytes.Reader
	path string
}

func (r *intReader) int64() int64 {
	i, err := binary.ReadVarint(r.Reader)
	if err != nil {
		errorf("import %q: read varint error: %v", r.path, err)
	}
	return i
}

func (r *intReader) uint64() uint64 {
	i, err := binary.ReadUvarint(r.Reader)
	if err != nil {
		errorf("import %q: read varint error: %v", r.path, err)
	}
	return i
}

// Keep this in sync with constants in iexport.go.
const (
	iexportVersionGo1_11   = 0
	iexportVersionPosCol   = 1
	iexportVersionGo1_18   = 2
	iexportVersionGenerics = 2
	iexportVersion         = iexportVersionGenerics

	iexportVersionCurrent = 2
)

type ident struct {
	pkg  *types.Package
	name string
}

const predeclReserved = 32

type itag uint64

const (
	// Types
	definedType itag = iota
	pointerType
	sliceType
	arrayType
	chanType
	mapType
	signatureType
	structType
	interfaceType
	typeParamType
	instanceType
	unionType
	aliasType
)

// Object tags
const (
	varTag          = 'V'
	funcTag         = 'F'
	genericFuncTag  = 'G'
	constTag        = 'C'
	aliasTag        = 'A'
	genericAliasTag = 'B'
	typeParamTag    = 'P'
	typeTag         = 'T'
	genericTypeTag  = 'U'
)

// IImportData imports a package from the serialized package data
// and returns 0 and a reference to the package.
// If the export data version is not recognized or the format is otherwise
// compromised, an error is returned.
func IImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (int, *types.Package, error) {
	pkgs, err := iimportCommon(fset, GetPackagesFromMap(imports), data, false, path, false, nil)
	if err != nil {
		return 0, nil, err
	}
	return 0, pkgs[0], nil
}

// IImportBundle imports a set of packages from the serialized package bundle.
func IImportBundle(fset *token.FileSet, imports map[string]*types.Package, data []byte) ([]*types.Package, error) {
	return iimportCommon(fset, GetPackagesFromMap(imports), data, true, "", false, nil)
}

// A GetPackagesFunc function obtains the non-nil symbols for a set of
// packages, creating and recursively importing them as needed. An
// implementation should store each package symbol is in the Pkg
// field of the items array.
//
// Any error causes importing to fail. This can be used to quickly read
// the import manifest of an export data file without fully decoding it.
type GetPackagesFunc = func(items []GetPackagesItem) error

// A GetPackagesItem is a request from the importer for the package
// symbol of the specified name and path.
type GetPackagesItem struct {
	Name, Path string
	Pkg        *types.Package // to be filled in by GetPackagesFunc call

	// private importer state
	pathOffset uint64
	nameIndex  map[string]uint64
}

// GetPackagesFromMap returns a GetPackagesFunc that retrieves
// packages from the given map of package path to package.
//
// The returned function may mutate m: each requested package that is not
// found is created with types.NewPackage and inserted into m.
func GetPackagesFromMap(m map[string]*types.Package) GetPackagesFunc {
	return func(items []GetPackagesItem) error {
		for i, item := range items {
			pkg, ok := m[item.Path]
			if !ok {
				pkg = types.NewPackage(item.Path, item.Name)
				m[item.Path] = pkg
			}
			items[i].Pkg = pkg
		}
		return nil
	}
}

func iimportCommon(fset *token.FileSet, getPackages GetPackagesFunc, data []byte, bundle bool, path string, shallow bool, reportf ReportFunc) (pkgs []*types.Package, err error) {
	const currentVersion = iexportVersionCurrent
	version := int64(-1)
	if !debug {
		defer func() {
			if e := recover(); e != nil {
				if bundle {
					err = fmt.Errorf("%v", e)
				} else if version > currentVersion {
					err = fmt.Errorf("cannot import %q (%v), export data is newer version - update tool", path, e)
				} else {
					err = fmt.Errorf("internal error while importing %q (%v); please report an issue", path, e)
				}
			}
		}()
	}

	r := &intReader{bytes.NewReader(data), path}

	if bundle {
		if v := r.uint64(); v != bundleVersion {
			errorf("unknown bundle format version %d", v)
		}
	}

	version = int64(r.uint64())
	switch version {
	case iexportVersionGo1_18, iexportVersionPosCol, iexportVersionGo1_11:
	default:
		if version > iexportVersionGo1_18 {
			errorf("unstable iexport format version %d, just rebuild compiler and std library", version)
		} else {
			errorf("unknown iexport format version %d", version)
		}
	}

	sLen := int64(r.uint64())
	var fLen int64
	var fileOffset []uint64
	if shallow {
		// Shallow mode uses a different position encoding.
		fLen = int64(r.uint64())
		fileOffset = make([]uint64, r.uint64())
		for i := range fileOffset {
			fileOffset[i] = r.uint64()
		}
	}
	dLen := int64(r.uint64())

	whence, _ := r.Seek(0, io.SeekCurrent)
	stringData := data[whence : whence+sLen]
	fileData := data[whence+sLen : whence+sLen+fLen]
	declData := data[whence+sLen+fLen : whence+sLen+fLen+dLen]
	r.Seek(sLen+fLen+dLen, io.SeekCurrent)

	p := iimporter{
		version: int(version),
		ipath:   path,
		shallow: shallow,
		reportf: reportf,

		stringData:  stringData,
		stringCache: make(map[uint64]string),
		fileOffset:  fileOffset,
		fileData:    fileData,
		fileCache:   make([]*token.File, len(fileOffset)),
		pkgCache:    make(map[uint64]*types.Package),

		declData: declData,
		pkgIndex: make(map[*types.Package]map[string]uint64),
		typCache: make(map[uint64]types.Type),
		// Separate map for typeparams, keyed by their package and unique
		// name.
		tparamIndex: make(map[ident]types.Type),

		fake: fakeFileSet{
			fset:  fset,
			files: make(map[string]*fileInfo),
		},
	}
	defer p.fake.setLines() // set lines for files in fset

	for i, pt := range predeclared() {
		p.typCache[uint64(i)] = pt
	}

	// Gather the relevant packages from the manifest.
	items := make([]GetPackagesItem, r.uint64())
	uniquePkgPaths := make(map[string]bool)
	for i := range items {
		pkgPathOff := r.uint64()
		pkgPath := p.stringAt(pkgPathOff)
		pkgName := p.stringAt(r.uint64())
		_ = r.uint64() // package height; unused by go/types

		if pkgPath == "" {
			pkgPath = path
		}
		items[i].Name = pkgName
		items[i].Path = pkgPath
		items[i].pathOffset = pkgPathOff

		// Read index for package.
		nameIndex := make(map[string]uint64)
		nSyms := r.uint64()
		// In shallow mode, only the current package (i=0) has an index.
		assert(!(shallow && i > 0 && nSyms != 0))
		for ; nSyms > 0; nSyms-- {
			name := p.stringAt(r.uint64())
			nameIndex[name] = r.uint64()
		}

		items[i].nameIndex = nameIndex

		uniquePkgPaths[pkgPath] = true
	}
	// Debugging #63822; hypothesis: there are duplicate PkgPaths.
	if len(uniquePkgPaths) != len(items) {
		reportf("found duplicate PkgPaths while reading export data manifest: %v", items)
	}

	// Request packages all at once from the client,
	// enabling a parallel implementation.
	if err := getPackages(items); err != nil {
		return nil, err // don't wrap this error
	}

	// Check the results and complete the index.
	pkgList := make([]*types.Package, len(items))
	for i, item := range items {
		pkg := item.Pkg
		if pkg == nil {
			errorf("internal error: getPackages returned nil package for %q", item.Path)
		} else if pkg.Path() != item.Path {
			errorf("internal error: getPackages returned wrong path %q, want %q", pkg.Path(), item.Path)
		} else if pkg.Name() != item.Name {
			errorf("internal error: getPackages returned wrong name %s for package %q, want %s", pkg.Name(), item.Path, item.Name)
		}
		p.pkgCache[item.pathOffset] = pkg
		p.pkgIndex[pkg] = item.nameIndex
		pkgList[i] = pkg
	}

	if bundle {
		pkgs = make([]*types.Package, r.uint64())
		for i := range pkgs {
			pkg := p.pkgAt(r.uint64())
			imps := make([]*types.Package, r.uint64())
			for j := range imps {
				imps[j] = p.pkgAt(r.uint64())
			}
			pkg.SetImports(imps)
			pkgs[i] = pkg
		}
	} else {
		if len(pkgList) == 0 {
			errorf("no packages found for %s", path)
			panic("unreachable")
		}
		pkgs = pkgList[:1]

		// record all referenced packages as imports
		list := slices.Clone(pkgList[1:])
		sort.Sort(byPath(list))
		pkgs[0].SetImports(list)
	}

	for _, pkg := range pkgs {
		if pkg.Complete() {
			continue
		}

		names := make([]string, 0, len(p.pkgIndex[pkg]))
		for name := range p.pkgIndex[pkg] {
			names = append(names, name)
		}
		sort.Strings(names)
		for _, name := range names {
			p.doDecl(pkg, name)
		}

		// package was imported completely and without errors
		pkg.MarkComplete()
	}

	// SetConstraint can't be called if the constraint type is not yet complete.
	// When type params are created in the typeParamTag case of (*importReader).obj(),
	// the associated constraint type may not be complete due to recursion.
	// Therefore, we defer calling SetConstraint there, and call it here instead
	// after all types are complete.
	for _, d := range p.later {
		d.t.SetConstraint(d.constraint)
	}

	for _, typ := range p.interfaceList {
		typ.Complete()
	}

	// Workaround for golang/go#61561. See the doc for instanceList for details.
	for _, typ := range p.instanceList {
		if iface, _ := typ.Underlying().(*types.Interface); iface != nil {
			iface.Complete()
		}
	}

	return pkgs, nil
}

type setConstraintArgs struct {
	t          *types.TypeParam
	constraint types.Type
}

type iimporter struct {
	version int
	ipath   string

	shallow bool
	reportf ReportFunc // if non-nil, used to report bugs

	stringData  []byte
	stringCache map[uint64]string
	fileOffset  []uint64 // fileOffset[i] is offset in fileData for info about file encoded as i
	fileData    []byte
	fileCache   []*token.File // memoized decoding of file encoded as i
	pkgCache    map[uint64]*types.Package

	declData    []byte
	pkgIndex    map[*types.Package]map[string]uint64
	typCache    map[uint64]types.Type
	tparamIndex map[ident]types.Type

	fake          fakeFileSet
	interfaceList []*types.Interface

	// Workaround for the go/types bug golang/go#61561: instances produced during
	// instantiation may contain incomplete interfaces. Here we only complete the
	// underlying type of the instance, which is the most common case but doesn't
	// handle parameterized interface literals defined deeper in the type.
	instanceList []types.Type // instances for later completion (see golang/go#61561)

	// Arguments for calls to SetConstraint that are deferred due to recursive types
	later []setConstraintArgs

	indent int // for tracing support
}

func (p *iimporter) trace(format string, args ...any) {
	if !trace {
		// Call sites should also be guarded, but having this check here allows
		// easily enabling/disabling debug trace statements.
		return
	}
	fmt.Printf(strings.Repeat("..", p.indent)+format+"\n", args...)
}

func (p *iimporter) doDecl(pkg *types.Package, name string) {
	if debug {
		p.trace("import decl %s", name)
		p.indent++
		defer func() {
			p.indent--
			p.trace("=> %s", name)
		}()
	}
	// See if we've already imported this declaration.
	if obj := pkg.Scope().Lookup(name); obj != nil {
		return
	}

	off, ok := p.pkgIndex[pkg][name]
	if !ok {
		// In deep mode, the index should be complete. In shallow
		// mode, we should have already recursively loaded necessary
		// dependencies so the above Lookup succeeds.
		errorf("%v.%v not in index", pkg, name)
	}

	r := &importReader{p: p}
	r.declReader.Reset(p.declData[off:])

	r.obj(pkg, name)
}

func (p *iimporter) stringAt(off uint64) string {
	if s, ok := p.stringCache[off]; ok {
		return s
	}

	slen, n := binary.Uvarint(p.stringData[off:])
	if n <= 0 {
		errorf("varint failed")
	}
	spos := off + uint64(n)
	s := string(p.stringData[spos : spos+slen])
	p.stringCache[off] = s
	return s
}

func (p *iimporter) fileAt(index uint64) *token.File {
	file := p.fileCache[index]
	if file == nil {
		off := p.fileOffset[index]
		file = p.decodeFile(intReader{bytes.NewReader(p.fileData[off:]), p.ipath})
		p.fileCache[index] = file
	}
	return file
}

func (p *iimporter) decodeFile(rd intReader) *token.File {
	filename := p.stringAt(rd.uint64())
	size := int(rd.uint64())
	file := p.fake.fset.AddFile(filename, -1, size)

	// SetLines requires a nondecreasing sequence.
	// Because it is common for clients to derive the interval
	// [start, start+len(name)] from a start position, and we
	// want to ensure that the end offset is on the same line,
	// we fill in the gaps of the sparse encoding with values
	// that strictly increase by the largest possible amount.
	// This allows us to avoid having to record the actual end
	// offset of each needed line.

	lines := make([]int, int(rd.uint64()))
	var index, offset int
	for i, n := 0, int(rd.uint64()); i < n; i++ {
		index += int(rd.uint64())
		offset += int(rd.uint64())
		lines[index] = offset

		// Ensure monotonicity between points.
		for j := index - 1; j > 0 && lines[j] == 0; j-- {
			lines[j] = lines[j+1] - 1
		}
	}

	// Ensure monotonicity after last point.
	for j := len(lines) - 1; j > 0 && lines[j] == 0; j-- {
		size--
		lines[j] = size
	}

	if !file.SetLines(lines) {
		errorf("SetLines failed: %d", lines) // can't happen
	}
	return file
}

func (p *iimporter) pkgAt(off uint64) *types.Package {
	if pkg, ok := p.pkgCache[off]; ok {
		return pkg
	}
	path := p.stringAt(off)
	errorf("missing package %q in %q", path, p.ipath)
	return nil
}

func (p *iimporter) typAt(off uint64, base *types.Named) types.Type {
	if t, ok := p.typCache[off]; ok && canReuse(base, t) {
		return t
	}

	if off < predeclReserved {
		errorf("predeclared type missing from cache: %v", off)
	}

	r := &importReader{p: p}
	r.declReader.Reset(p.declData[off-predeclReserved:])
	t := r.doType(base)

	if canReuse(base, t) {
		p.typCache[off] = t
	}
	return t
}

// canReuse reports whether the type rhs on the RHS of the declaration for def
// may be re-used.
//
// Specifically, if def is non-nil and rhs is an interface type with methods, it
// may not be re-used because we have a convention of setting the receiver type
// for interface methods to def.
func canReuse(def *types.Named, rhs types.Type) bool {
	if def == nil {
		return true
	}
	iface, _ := types.Unalias(rhs).(*types.Interface)
	if iface == nil {
		return true
	}
	// Don't use iface.Empty() here as iface may not be complete.
	return iface.NumEmbeddeds() == 0 && iface.NumExplicitMethods() == 0
}

type importReader struct {
	p          *iimporter
	declReader bytes.Reader
	prevFile   string
	prevLine   int64
	prevColumn int64
}

// markBlack is redefined in iimport_go123.go, to work around golang/go#69912.
//
// If TypeNames are not marked black (in the sense of go/types cycle
// detection), they may be mutated when dot-imported. Fix this by punching a
// hole through the type, when compiling with Go 1.23. (The bug has been fixed
// for 1.24, but the fix was not worth back-porting).
var markBlack = func(name *types.TypeName) {}

// obj decodes and declares the package-level object denoted by (pkg, name).
func (r *importReader) obj(pkg *types.Package, name string) {
	tag := r.byte()
	pos := r.pos()

	switch tag {
	case aliasTag, genericAliasTag:
		var tparams []*types.TypeParam
		if tag == genericAliasTag {
			tparams = r.tparamList()
		}
		typ := r.typ()
		obj := aliases.New(pos, pkg, name, typ, tparams)
		markBlack(obj) // workaround for golang/go#69912
		r.declare(obj)

	case constTag:
		typ, val := r.value()

		r.declare(types.NewConst(pos, pkg, name, typ, val))

	case funcTag, genericFuncTag:
		var tparams []*types.TypeParam
		if tag == genericFuncTag {
			tparams = r.tparamList()
		}
		sig := r.signature(pkg, nil, nil, tparams)
		r.declare(types.NewFunc(pos, pkg, name, sig))

	case typeTag, genericTypeTag:
		// Types can be recursive. We need to setup a stub
		// declaration before recursing.
		obj := types.NewTypeName(pos, pkg, name, nil)
		named := types.NewNamed(obj, nil, nil)

		markBlack(obj) // workaround for golang/go#69912

		// Declare obj before calling r.tparamList, so the new type name is recognized
		// if used in the constraint of one of its own typeparams (see #48280).
		r.declare(obj)
		if tag == genericTypeTag {
			tparams := r.tparamList()
			named.SetTypeParams(tparams)
		}

		underlying := r.p.typAt(r.uint64(), named).Underlying()
		named.SetUnderlying(underlying)

		if !isInterface(underlying) {
			for n := r.uint64(); n > 0; n-- {
				mpos := r.pos()
				mname := r.ident()
				recv := r.param(pkg)

				// If the receiver has any targs, set those as the
				// rparams of the method (since those are the
				// typeparams being used in the method sig/body).
				_, recvNamed := typesinternal.ReceiverNamed(recv)
				targs := recvNamed.TypeArgs()
				var rparams []*types.TypeParam
				if targs.Len() > 0 {
					rparams = make([]*types.TypeParam, targs.Len())
					for i := range rparams {
						rparams[i] = types.Unalias(targs.At(i)).(*types.TypeParam)
					}
				}
				msig := r.signature(pkg, recv, rparams, nil)

				named.AddMethod(types.NewFunc(mpos, pkg, mname, msig))
			}
		}

	case typeParamTag:
		// We need to "declare" a typeparam in order to have a name that
		// can be referenced recursively (if needed) in the type param's
		// bound.
		if r.p.version < iexportVersionGenerics {
			errorf("unexpected type param type")
		}
		name0 := tparamName(name)
		tn := types.NewTypeName(pos, pkg, name0, nil)
		t := types.NewTypeParam(tn, nil)

		// To handle recursive references to the typeparam within its
		// bound, save the partial type in tparamIndex before reading the bounds.
		id := ident{pkg, name}
		r.p.tparamIndex[id] = t
		var implicit bool
		if r.p.version >= iexportVersionGo1_18 {
			implicit = r.bool()
		}
		constraint := r.typ()
		if implicit {
			iface, _ := types.Unalias(constraint).(*types.Interface)
			if iface == nil {
				errorf("non-interface constraint marked implicit")
			}
			iface.MarkImplicit()
		}
		// The constraint type may not be complete, if we
		// are in the middle of a type recursion involving type
		// constraints. So, we defer SetConstraint until we have
		// completely set up all types in ImportData.
		r.p.later = append(r.p.later, setConstraintArgs{t: t, constraint: constraint})

	case varTag:
		typ := r.typ()

		v := types.NewVar(pos, pkg, name, typ)
		typesinternal.SetVarKind(v, typesinternal.PackageVar)
		r.declare(v)

	default:
		errorf("unexpected tag: %v", tag)
	}
}

func (r *importReader) declare(obj types.Object) {
	obj.Pkg().Scope().Insert(obj)
}

func (r *importReader) value() (typ types.Type, val constant.Value) {
	typ = r.typ()
	if r.p.version >= iexportVersionGo1_18 {
		// TODO: add support for using the kind.
		_ = constant.Kind(r.int64())
	}

	switch b := typ.Underlying().(*types.Basic); b.Info() & types.IsConstType {
	case types.IsBoolean:
		val = constant.MakeBool(r.bool())

	case types.IsString:
		val = constant.MakeString(r.string())

	case types.IsInteger:
		var x big.Int
		r.mpint(&x, b)
		val = constant.Make(&x)

	case types.IsFloat:
		val = r.mpfloat(b)

	case types.IsComplex:
		re := r.mpfloat(b)
		im := r.mpfloat(b)
		val = constant.BinaryOp(re, token.ADD, constant.MakeImag(im))

	default:
		if b.Kind() == types.Invalid {
			val = constant.MakeUnknown()
			return
		}
		errorf("unexpected type %v", typ) // panics
		panic("unreachable")
	}

	return
}

func intSize(b *types.Basic) (signed bool, maxBytes uint) {
	if (b.Info() & types.IsUntyped) != 0 {
		return true, 64
	}

	switch b.Kind() {
	case types.Float32, types.Complex64:
		return true, 3
	case types.Float64, types.Complex128:
		return true, 7
	}

	signed = (b.Info() & types.IsUnsigned) == 0
	switch b.Kind() {
	case types.Int8, types.Uint8:
		maxBytes = 1
	case types.Int16, types.Uint16:
		maxBytes = 2
	case types.Int32, types.Uint32:
		maxBytes = 4
	default:
		maxBytes = 8
	}

	return
}

func (r *importReader) mpint(x *big.Int, typ *types.Basic) {
	signed, maxBytes := intSize(typ)

	maxSmall := 256 - maxBytes
	if signed {
		maxSmall = 256 - 2*maxBytes
	}
	if maxBytes == 1 {
		maxSmall = 256
	}

	n, _ := r.declReader.ReadByte()
	if uint(n) < maxSmall {
		v := int64(n)
		if signed {
			v >>= 1
			if n&1 != 0 {
				v = ^v
			}
		}
		x.SetInt64(v)
		return
	}

	v := -n
	if signed {
		v = -(n &^ 1) >> 1
	}
	if v < 1 || uint(v) > maxBytes {
		errorf("weird decoding: %v, %v => %v", n, signed, v)
	}
	b := make([]byte, v)
	io.ReadFull(&r.declReader, b)
	x.SetBytes(b)
	if signed && n&1 != 0 {
		x.Neg(x)
	}
}

func (r *importReader) mpfloat(typ *types.Basic) constant.Value {
	var mant big.Int
	r.mpint(&mant, typ)
	var f big.Float
	f.SetInt(&mant)
	if f.Sign() != 0 {
		f.SetMantExp(&f, int(r.int64()))
	}
	return constant.Make(&f)
}

func (r *importReader) ident() string {
	return r.string()
}

func (r *importReader) qualifiedIdent() (*types.Package, string) {
	name := r.string()
	pkg := r.pkg()
	return pkg, name
}

func (r *importReader) pos() token.Pos {
	if r.p.shallow {
		// precise offsets are encoded only in shallow mode
		return r.posv2()
	}
	if r.p.version >= iexportVersionPosCol {
		r.posv1()
	} else {
		r.posv0()
	}

	if r.prevFile == "" && r.prevLine == 0 && r.prevColumn == 0 {
		return token.NoPos
	}
	return r.p.fake.pos(r.prevFile, int(r.prevLine), int(r.prevColumn))
}

func (r *importReader) posv0() {
	delta := r.int64()
	if delta != deltaNewFile {
		r.prevLine += delta
	} else if l := r.int64(); l == -1 {
		r.prevLine += deltaNewFile
	} else {
		r.prevFile = r.string()
		r.prevLine = l
	}
}

func (r *importReader) posv1() {
	delta := r.int64()
	r.prevColumn += delta >> 1
	if delta&1 != 0 {
		delta = r.int64()
		r.prevLine += delta >> 1
		if delta&1 != 0 {
			r.prevFile = r.string()
		}
	}
}

func (r *importReader) posv2() token.Pos {
	file := r.uint64()
	if file == 0 {
		return token.NoPos
	}
	tf := r.p.fileAt(file - 1)
	return tf.Pos(int(r.uint64()))
}

func (r *importReader) typ() types.Type {
	return r.p.typAt(r.uint64(), nil)
}

func isInterface(t types.Type) bool {
	_, ok := types.Unalias(t).(*types.Interface)
	return ok
}

func (r *importReader) pkg() *types.Package { return r.p.pkgAt(r.uint64()) }
func (r *importReader) string() string      { return r.p.stringAt(r.uint64()) }

func (r *importReader) doType(base *types.Named) (res types.Type) {
	k := r.kind()
	if debug {
		r.p.trace("importing type %d (base: %v)", k, base)
		r.p.indent++
		defer func() {
			r.p.indent--
			r.p.trace("=> %s", res)
		}()
	}
	switch k {
	default:
		errorf("unexpected kind tag in %q: %v", r.p.ipath, k)
		return nil

	case aliasType, definedType:
		pkg, name := r.qualifiedIdent()
		r.p.doDecl(pkg, name)
		return pkg.Scope().Lookup(name).(*types.TypeName).Type()
	case pointerType:
		return types.NewPointer(r.typ())
	case sliceType:
		return types.NewSlice(r.typ())
	case arrayType:
		n := r.uint64()
		return types.NewArray(r.typ(), int64(n))
	case chanType:
		dir := chanDir(int(r.uint64()))
		return types.NewChan(dir, r.typ())
	case mapType:
		return types.NewMap(r.typ(), r.typ())
	case signatureType:
		paramPkg := r.pkg()
		return r.signature(paramPkg, nil, nil, nil)

	case structType:
		fieldPkg := r.pkg()

		fields := make([]*types.Var, r.uint64())
		tags := make([]string, len(fields))
		for i := range fields {
			var field *types.Var
			if r.p.shallow {
				field, _ = r.objectPathObject().(*types.Var)
			}

			fpos := r.pos()
			fname := r.ident()
			ftyp := r.typ()
			emb := r.bool()
			tag := r.string()

			// Either this is not a shallow import, the field is local, or the
			// encoded objectPath failed to produce an object (a bug).
			//
			// Even in this last, buggy case, fall back on creating a new field. As
			// discussed in iexport.go, this is not correct, but mostly works and is
			// preferable to failing (for now at least).
			if field == nil {
				field = types.NewField(fpos, fieldPkg, fname, ftyp, emb)
			}

			fields[i] = field
			tags[i] = tag
		}
		return types.NewStruct(fields, tags)

	case interfaceType:
		methodPkg := r.pkg() // qualifies methods and their param/result vars

		embeddeds := make([]types.Type, r.uint64())
		for i := range embeddeds {
			_ = r.pos()
			embeddeds[i] = r.typ()
		}

		methods := make([]*types.Func, r.uint64())
		for i := range methods {
			var method *types.Func
			if r.p.shallow {
				method, _ = r.objectPathObject().(*types.Func)
			}

			mpos := r.pos()
			mname := r.ident()

			// TODO(mdempsky): Matches bimport.go, but I
			// don't agree with this.
			var recv *types.Var
			if base != nil {
				recv = types.NewVar(token.NoPos, methodPkg, "", base)
			}
			msig := r.signature(methodPkg, recv, nil, nil)

			if method == nil {
				method = types.NewFunc(mpos, methodPkg, mname, msig)
			}
			methods[i] = method
		}

		typ := types.NewInterfaceType(methods, embeddeds)
		r.p.interfaceList = append(r.p.interfaceList, typ)
		return typ

	case typeParamType:
		if r.p.version < iexportVersionGenerics {
			errorf("unexpected type param type")
		}
		pkg, name := r.qualifiedIdent()
		id := ident{pkg, name}
		if t, ok := r.p.tparamIndex[id]; ok {
			// We're already in the process of importing this typeparam.
			return t
		}
		// Otherwise, import the definition of the typeparam now.
		r.p.doDecl(pkg, name)
		return r.p.tparamIndex[id]

	case instanceType:
		if r.p.version < iexportVersionGenerics {
			errorf("unexpected instantiation type")
		}
		// pos does not matter for instances: they are positioned on the original
		// type.
		_ = r.pos()
		len := r.uint64()
		targs := make([]types.Type, len)
		for i := range targs {
			targs[i] = r.typ()
		}
		baseType := r.typ()
		// The imported instantiated type doesn't include any methods, so
		// we must always use the methods of the base (orig) type.
		// TODO provide a non-nil *Environment
		t, _ := types.Instantiate(nil, baseType, targs, false)

		// Workaround for golang/go#61561. See the doc for instanceList for details.
		r.p.instanceList = append(r.p.instanceList, t)
		return t

	case unionType:
		if r.p.version < iexportVersionGenerics {
			errorf("unexpected instantiation type")
		}
		terms := make([]*types.Term, r.uint64())
		for i := range terms {
			terms[i] = types.NewTerm(r.bool(), r.typ())
		}
		return types.NewUnion(terms)
	}
}

func (r *importReader) kind() itag {
	return itag(r.uint64())
}

// objectPathObject is the inverse of exportWriter.objectPath.
//
// In shallow mode, certain fields and methods may need to be looked up in an
// imported package. See the doc for exportWriter.objectPath for a full
// explanation.
func (r *importReader) objectPathObject() types.Object {
	objPath := objectpath.Path(r.string())
	if objPath == "" {
		return nil
	}
	pkg := r.pkg()
	obj, err := objectpath.Object(pkg, objPath)
	if err != nil {
		if r.p.reportf != nil {
			r.p.reportf("failed to find object for objectPath %q: %v", objPath, err)
		}
	}
	return obj
}

func (r *importReader) signature(paramPkg *types.Package, recv *types.Var, rparams []*types.TypeParam, tparams []*types.TypeParam) *types.Signature {
	params := r.paramList(paramPkg)
	results := r.paramList(paramPkg)
	variadic := params.Len() > 0 && r.bool()
	return types.NewSignatureType(recv, rparams, tparams, params, results, variadic)
}

func (r *importReader) tparamList() []*types.TypeParam {
	n := r.uint64()
	if n == 0 {
		return nil
	}
	xs := make([]*types.TypeParam, n)
	for i := range xs {
		// Note: the standard library importer is tolerant of nil types here,
		// though would panic in SetTypeParams.
		xs[i] = types.Unalias(r.typ()).(*types.TypeParam)
	}
	return xs
}

func (r *importReader) paramList(pkg *types.Package) *types.Tuple {
	xs := make([]*types.Var, r.uint64())
	for i := range xs {
		xs[i] = r.param(pkg)
	}
	return types.NewTuple(xs...)
}

func (r *importReader) param(pkg *types.Package) *types.Var {
	pos := r.pos()
	name := r.ident()
	typ := r.typ()
	return types.NewParam(pos, pkg, name, typ)
}

func (r *importReader) bool() bool {
	return r.uint64() != 0
}

func (r *importReader) int64() int64 {
	n, err := binary.ReadVarint(&r.declReader)
	if err != nil {
		errorf("readVarint: %v", err)
	}
	return n
}

func (r *importReader) uint64() uint64 {
	n, err := binary.ReadUvarint(&r.declReader)
	if err != nil {
		errorf("readUvarint: %v", err)
	}
	return n
}

func (r *importReader) byte() byte {
	x, err := r.declReader.ReadByte()
	if err != nil {
		errorf("declReader.ReadByte: %v", err)
	}
	return x
}

type byPath []*types.Package

func (a byPath) Len() int           { return len(a) }
func (a byPath) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }
func (a byPath) Less(i, j int) bool { return a[i].Path() < a[j].Path() }


================================================
FILE: internal/gcimporter/israce_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build race

package gcimporter_test

func init() {
	isRace = true
}


================================================
FILE: internal/gcimporter/main.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The gcimporter command reads the compiler's export data for the
// named packages and prints the decoded type information.
//
// It is provided for debugging export data problems.
package main

import (
	"bytes"
	"flag"
	"fmt"
	"go/token"
	"go/types"
	"log"
	"os"
	"sort"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/gcimporter"
)

func main() {
	flag.Parse()
	cfg := &packages.Config{
		Fset: token.NewFileSet(),
		// Don't request NeedTypes: we want to be certain that
		// we loaded the types ourselves, from export data.
		Mode: packages.NeedName | packages.NeedExportFile,
	}
	pkgs, err := packages.Load(cfg, flag.Args()...)
	if err != nil {
		log.Fatal(err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		os.Exit(1)
	}

	for _, pkg := range pkgs {
		// Read types from compiler's unified export data file.
		// This Package may included non-exported functions if they
		// are called by inlinable exported functions.
		var tpkg1 *types.Package
		{
			export, err := os.ReadFile(pkg.ExportFile)
			if err != nil {
				log.Fatalf("can't read %q export data: %v", pkg.PkgPath, err)
			}
			r, err := gcexportdata.NewReader(bytes.NewReader(export))
			if err != nil {
				log.Fatalf("reading export data %s: %v", pkg.ExportFile, err)
			}
			tpkg1, err = gcexportdata.Read(r, cfg.Fset, make(map[string]*types.Package), pkg.PkgPath)
			if err != nil {
				log.Fatalf("decoding export data: %v", err)
			}
		}
		fmt.Println("# Read from compiler's unified export data:")
		printPackage(tpkg1)

		// Now reexport as indexed (deep) export data, and reimport.
		// The Package will contain only exported symbols.
		var tpkg2 *types.Package
		{
			var out bytes.Buffer
			if err := gcimporter.IExportData(&out, cfg.Fset, tpkg1); err != nil {
				log.Fatal(err)
			}
			var err error
			_, tpkg2, err = gcimporter.IImportData(cfg.Fset, make(map[string]*types.Package), out.Bytes(), tpkg1.Path())
			if err != nil {
				log.Fatal(err)
			}
		}
		fmt.Println("# After round-tripping through indexed export data:")
		printPackage(tpkg2)
	}
}

func printPackage(pkg *types.Package) {
	fmt.Printf("package %s %q\n", pkg.Name(), pkg.Path())

	if !pkg.Complete() {
		fmt.Printf("\thas incomplete exported type info\n")
	}

	// imports
	var lines []string
	for _, imp := range pkg.Imports() {
		lines = append(lines, fmt.Sprintf("\timport %q", imp.Path()))
	}
	sort.Strings(lines)
	for _, line := range lines {
		fmt.Println(line)
	}

	// types of package members
	qual := types.RelativeTo(pkg)
	scope := pkg.Scope()
	for _, name := range scope.Names() {
		obj := scope.Lookup(name)
		fmt.Printf("\t%s\n", types.ObjectString(obj, qual))
		if _, ok := obj.(*types.TypeName); ok {
			for _, meth := range typeutil.IntuitiveMethodSet(obj.Type(), nil) {
				fmt.Printf("\t%s\n", types.SelectionString(meth, qual))
			}
		}
	}

	fmt.Println()
}


================================================
FILE: internal/gcimporter/predeclared.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter

import (
	"go/types"
	"sync"
)

// predecl is a cache for the predeclared types in types.Universe.
//
// Cache a distinct result based on the runtime value of any.
// The pointer value of the any type varies based on GODEBUG settings.
var predeclMu sync.Mutex
var predecl map[types.Type][]types.Type

func predeclared() []types.Type {
	anyt := types.Universe.Lookup("any").Type()

	predeclMu.Lock()
	defer predeclMu.Unlock()

	if pre, ok := predecl[anyt]; ok {
		return pre
	}

	if predecl == nil {
		predecl = make(map[types.Type][]types.Type)
	}

	decls := []types.Type{ // basic types
		types.Typ[types.Bool],
		types.Typ[types.Int],
		types.Typ[types.Int8],
		types.Typ[types.Int16],
		types.Typ[types.Int32],
		types.Typ[types.Int64],
		types.Typ[types.Uint],
		types.Typ[types.Uint8],
		types.Typ[types.Uint16],
		types.Typ[types.Uint32],
		types.Typ[types.Uint64],
		types.Typ[types.Uintptr],
		types.Typ[types.Float32],
		types.Typ[types.Float64],
		types.Typ[types.Complex64],
		types.Typ[types.Complex128],
		types.Typ[types.String],

		// basic type aliases
		types.Universe.Lookup("byte").Type(),
		types.Universe.Lookup("rune").Type(),

		// error
		types.Universe.Lookup("error").Type(),

		// untyped types
		types.Typ[types.UntypedBool],
		types.Typ[types.UntypedInt],
		types.Typ[types.UntypedRune],
		types.Typ[types.UntypedFloat],
		types.Typ[types.UntypedComplex],
		types.Typ[types.UntypedString],
		types.Typ[types.UntypedNil],

		// package unsafe
		types.Typ[types.UnsafePointer],

		// invalid type
		types.Typ[types.Invalid], // only appears in packages with errors

		// used internally by gc; never used by this package or in .a files
		anyType{},

		// comparable
		types.Universe.Lookup("comparable").Type(),

		// any
		anyt,
	}

	predecl[anyt] = decls
	return decls
}

type anyType struct{}

func (t anyType) Underlying() types.Type { return t }
func (t anyType) String() string         { return "any" }


================================================
FILE: internal/gcimporter/shallow_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"strings"
	"testing"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/gcimporter"
	"golang.org/x/tools/internal/testenv"
)

// TestShallowStd type-checks the standard library using shallow export data.
func TestShallowStd(t *testing.T) {
	if testing.Short() {
		t.Skip("skipping in short mode; too slow (https://golang.org/issue/14113)")
	}
	testenv.NeedsTool(t, "go")

	// Load import graph of the standard library.
	// (No parsing or type-checking.)
	cfg := &packages.Config{
		Mode: packages.NeedImports |
			packages.NeedName |
			packages.NeedFiles | // see https://github.com/golang/go/issues/56632
			packages.NeedCompiledGoFiles,
		Tests: false,
	}
	pkgs, err := packages.Load(cfg, "std")
	if err != nil {
		t.Fatalf("load: %v", err)
	}
	if len(pkgs) < 200 {
		t.Fatalf("too few packages: %d", len(pkgs))
	}

	// Type check the packages in parallel postorder.
	done := make(map[*packages.Package]chan struct{})
	packages.Visit(pkgs, nil, func(p *packages.Package) {
		done[p] = make(chan struct{})
	})
	packages.Visit(pkgs, nil,
		func(pkg *packages.Package) {
			go func() {
				// Wait for all deps to be done.
				for _, imp := range pkg.Imports {
					<-done[imp]
				}
				typecheck(t, pkg)
				close(done[pkg])
			}()
		})
	for _, root := range pkgs {
		<-done[root]
	}
}

// typecheck reads, parses, and type-checks a package.
// It squirrels the export data in the ppkg.ExportFile field.
func typecheck(t *testing.T, ppkg *packages.Package) {
	if ppkg.PkgPath == "unsafe" {
		return // unsafe is special
	}

	// Create a local FileSet just for this package.
	fset := token.NewFileSet()

	// Parse files in parallel.
	syntax := make([]*ast.File, len(ppkg.CompiledGoFiles))
	var group errgroup.Group
	for i, filename := range ppkg.CompiledGoFiles {
		group.Go(func() error {
			f, err := parser.ParseFile(fset, filename, nil, parser.SkipObjectResolution)
			if err != nil {
				return err // e.g. missing file
			}
			syntax[i] = f
			return nil
		})
	}
	if err := group.Wait(); err != nil {
		t.Fatal(err)
	}
	// Inv: all files were successfully parsed.

	// Build map of dependencies by package path.
	// (We don't compute this mapping for the entire
	// packages graph because it is not globally consistent.)
	depsByPkgPath := make(map[string]*packages.Package)
	{
		var visit func(*packages.Package)
		visit = func(pkg *packages.Package) {
			if depsByPkgPath[pkg.PkgPath] == nil {
				depsByPkgPath[pkg.PkgPath] = pkg
				for path := range pkg.Imports {
					visit(pkg.Imports[path])
				}
			}
		}
		visit(ppkg)
	}

	// importer state
	var (
		loadFromExportData func(*packages.Package) (*types.Package, error)
		importMap          = map[string]*types.Package{ // keys are PackagePaths
			ppkg.PkgPath: types.NewPackage(ppkg.PkgPath, ppkg.Name),
		}
	)
	loadFromExportData = func(imp *packages.Package) (*types.Package, error) {
		export := []byte(imp.ExportFile)
		getPackages := func(items []gcimporter.GetPackagesItem) error {
			for i, item := range items {
				pkg, ok := importMap[item.Path]
				if !ok {
					dep, ok := depsByPkgPath[item.Path]
					if !ok {
						return fmt.Errorf("can't find dependency: %q", item.Path)
					}
					pkg = types.NewPackage(item.Path, dep.Name)
					importMap[item.Path] = pkg
					loadFromExportData(dep) // side effect: populate package scope
				}
				items[i].Pkg = pkg
			}
			return nil
		}
		return gcimporter.IImportShallow(fset, getPackages, export, imp.PkgPath, nil)
	}

	// Type-check the syntax trees.
	cfg := &types.Config{
		Error: func(e error) {
			t.Error(e)
		},
		Importer: importerFunc(func(importPath string) (*types.Package, error) {
			if importPath == "unsafe" {
				return types.Unsafe, nil // unsafe has no exportdata
			}
			imp, ok := ppkg.Imports[importPath]
			if !ok {
				return nil, fmt.Errorf("missing import %q", importPath)
			}
			return loadFromExportData(imp)
		}),
	}

	// (Use NewChecker+Files to ensure Package.Name is set explicitly.)
	tpkg := types.NewPackage(ppkg.PkgPath, ppkg.Name)
	_ = types.NewChecker(cfg, fset, tpkg, nil).Files(syntax) // ignore error
	// Check sanity.
	postTypeCheck(t, fset, tpkg)

	// Save the export data.
	data, err := gcimporter.IExportShallow(fset, tpkg, nil)
	if err != nil {
		t.Fatalf("internal error marshalling export data: %v", err)
	}
	ppkg.ExportFile = string(data)
}

// postTypeCheck is called after a package is type checked.
// We use it to assert additional correctness properties,
// for example, that the apparent location of "fmt.Println"
// corresponds to its source location: in other words,
// export+import preserves high-fidelity positions.
func postTypeCheck(t *testing.T, fset *token.FileSet, pkg *types.Package) {
	// We hard-code a few interesting test-case objects.
	var obj types.Object
	switch pkg.Path() {
	case "fmt":
		// func fmt.Println
		obj = pkg.Scope().Lookup("Println")
	case "net/http":
		// method (*http.Request).ParseForm
		req := pkg.Scope().Lookup("Request")
		obj, _, _ = types.LookupFieldOrMethod(req.Type(), true, pkg, "ParseForm")
	default:
		return
	}
	if obj == nil {
		t.Errorf("object not found in package %s", pkg.Path())
		return
	}

	// Now check the source fidelity of the object's position.
	posn := fset.Position(obj.Pos())
	data, err := os.ReadFile(posn.Filename)
	if err != nil {
		t.Errorf("can't read source file declaring %v: %v", obj, err)
		return
	}

	// Check line and column denote a source interval containing the object's identifier.
	line := strings.Split(string(data), "\n")[posn.Line-1]

	if id := line[posn.Column-1 : posn.Column-1+len(obj.Name())]; id != obj.Name() {
		t.Errorf("%+v: expected declaration of %v at this line, column; got %q", posn, obj, line)
	}

	// Check offset.
	if id := string(data[posn.Offset : posn.Offset+len(obj.Name())]); id != obj.Name() {
		t.Errorf("%+v: expected declaration of %v at this offset; got %q", posn, obj, id)
	}

	// Check commutativity of Position() and start+len(name) operations:
	// Position(startPos+len(name)) == Position(startPos) + len(name).
	// This important property is a consequence of the way in which the
	// decoder fills the gaps in the sparse line-start offset table.
	endPosn := fset.Position(obj.Pos() + token.Pos(len(obj.Name())))
	wantEndPosn := token.Position{
		Filename: posn.Filename,
		Offset:   posn.Offset + len(obj.Name()),
		Line:     posn.Line,
		Column:   posn.Column + len(obj.Name()),
	}
	if endPosn != wantEndPosn {
		t.Errorf("%+v: expected end Position of %v here; was at %+v", wantEndPosn, obj, endPosn)
	}
}


================================================
FILE: internal/gcimporter/stdlib_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter_test

import (
	"bytes"
	"fmt"
	"go/token"
	"go/types"
	"runtime"
	"testing"
	"unsafe"

	"golang.org/x/tools/go/gcexportdata"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
)

// TestStdlib ensures that all packages in std and x/tools can be
// type-checked using export data.
func TestStdlib(t *testing.T) {
	testenv.NeedsGoPackages(t)

	// gcexportdata.Read rapidly consumes FileSet address space,
	// so disable the test on 32-bit machines.
	// (We could use a fresh FileSet per type-check, but that
	// would require us to re-parse the source using it.)
	if unsafe.Sizeof(token.NoPos) < 8 {
		t.Skip("skipping test on 32-bit machine")
	}

	// Load, parse and type-check the standard library.
	// If we have the full source code for x/tools, also load and type-check that.
	cfg := &packages.Config{Mode: packages.LoadAllSyntax}
	patterns := []string{"std"}
	minPkgs := 225 // 'GOOS=plan9 go1.18 list std | wc -l' reports 228; most other platforms have more.
	switch runtime.GOOS {
	case "android", "ios":
		// The go_.*_exec script for mobile builders only copies over the source tree
		// for the package under test.
	default:
		patterns = append(patterns, "golang.org/x/tools/...")
		minPkgs += 160 // At the time of writing, 'GOOS=plan9 go list ./... | wc -l' reports 188.
	}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		t.Fatalf("failed to load/parse/type-check: %v", err)
	}
	if packages.PrintErrors(pkgs) > 0 {
		t.Fatal("there were errors during loading")
	}
	if len(pkgs) < minPkgs {
		t.Errorf("too few packages (%d) were loaded", len(pkgs))
	}

	export := make(map[string][]byte) // keys are package IDs

	// Re-type check them all in post-order, using export data.
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		packages := make(map[string]*types.Package) // keys are package paths
		cfg := &types.Config{
			Error: func(e error) {
				t.Errorf("type error: %v", e)
			},
			Importer: importerFunc(func(importPath string) (*types.Package, error) {
				// Resolve import path to (vendored?) package path.
				imported := pkg.Imports[importPath]

				if imported.PkgPath == "unsafe" {
					return types.Unsafe, nil // unsafe has no exportdata
				}

				data, ok := export[imported.ID]
				if !ok {
					return nil, fmt.Errorf("missing export data for %s", importPath)
				}
				return gcexportdata.Read(bytes.NewReader(data), pkg.Fset, packages, imported.PkgPath)
			}),
		}

		// Re-typecheck the syntax and save the export data in the map.
		newPkg := types.NewPackage(pkg.PkgPath, pkg.Name)
		check := types.NewChecker(cfg, pkg.Fset, newPkg, nil)
		check.Files(pkg.Syntax)

		var out bytes.Buffer
		if err := gcexportdata.Write(&out, pkg.Fset, newPkg); err != nil {
			t.Fatalf("internal error writing export data: %v", err)
		}
		export[pkg.ID] = out.Bytes()
	})
}


================================================
FILE: internal/gcimporter/support.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gcimporter

import (
	"bufio"
	"io"
	"strconv"
	"strings"
)

// Copy of $GOROOT/src/cmd/internal/archive.ReadHeader.
func readArchiveHeader(b *bufio.Reader, name string) int {
	// architecture-independent object file output
	const HeaderSize = 60

	var buf [HeaderSize]byte
	if _, err := io.ReadFull(b, buf[:]); err != nil {
		return -1
	}
	aname := strings.Trim(string(buf[0:16]), " ")
	if !strings.HasPrefix(aname, name) {
		return -1
	}
	asize := strings.Trim(string(buf[48:58]), " ")
	i, _ := strconv.Atoi(asize)
	return i
}


================================================
FILE: internal/gcimporter/testdata/a/a.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Input for TestIssue13566

package a

import "encoding/json"

type A struct {
	a    *A
	json json.RawMessage
}


================================================
FILE: internal/gcimporter/testdata/a.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Input for TestIssue13566

package a

import "encoding/json"

type A struct {
	a    *A
	json json.RawMessage
}


================================================
FILE: internal/gcimporter/testdata/aliases/a/a.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

type A[T any] = *T

type B = struct{ F int }

func F() B {
	type a[T any] = struct{ F T }
	return a[int]{}
}


================================================
FILE: internal/gcimporter/testdata/aliases/b/b.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package b

import "./a"

type B[S any] = struct {
	F a.A[[]S]
}


================================================
FILE: internal/gcimporter/testdata/aliases/c/c.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package c

import (
	"./a"
	"./b"
)

type c[V any] = struct {
	G b.B[[3]V]
}

var S struct{ F int } = a.B{}
var T struct{ F int } = a.F()

var U a.A[string] = (*string)(nil)
var V a.A[int] = (*int)(nil)

var W b.B[string] = struct{ F *[]string }{}
var X b.B[int] = struct{ F *[]int }{}

var Y c[string] = struct{ G struct{ F *[][3]string } }{}
var Z c[int] = struct{ G struct{ F *[][3]int } }{}


================================================
FILE: internal/gcimporter/testdata/b.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Input for TestIssue13566

package b

import "./a"

type A a.A


================================================
FILE: internal/gcimporter/testdata/exports.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is used to generate an object file which
// serves as test file for gcimporter_test.go.

package exports

import (
	"go/ast"
)

// Issue 3682: Correctly read dotted identifiers from export data.
const init1 = 0

func init() {}

const (
	C0 int = 0
	C1     = 3.14159265
	C2     = 2.718281828i
	C3     = -123.456e-789
	C4     = +123.456E+789
	C5     = 1234i
	C6     = "foo\n"
	C7     = `bar\n`
)

type (
	T1  int
	T2  [10]int
	T3  []int
	T4  *int
	T5  chan int
	T6a chan<- int
	T6b chan (<-chan int)
	T6c chan<- (chan int)
	T7  <-chan *ast.File
	T8  struct{}
	T9  struct {
		a    int
		b, c float32
		d    []string `go:"tag"`
	}
	T10 struct {
		T8
		T9
		_ *T10
	}
	T11 map[int]string
	T12 interface{}
	T13 interface {
		m1()
		m2(int) float32
	}
	T14 interface {
		T12
		T13
		m3(x ...struct{}) []T9
	}
	T15 func()
	T16 func(int)
	T17 func(x int)
	T18 func() float32
	T19 func() (x float32)
	T20 func(...interface{})
	T21 struct{ next *T21 }
	T22 struct{ link *T23 }
	T23 struct{ link *T22 }
	T24 *T24
	T25 *T26
	T26 *T27
	T27 *T25
	T28 func(T28) T28
)

var (
	V0 int
	V1 = -991.0
)

func F1()         {}
func F2(x int)    {}
func F3() int     { return 0 }
func F4() float32 { return 0 }
func F5(a, b, c int, u, v, w struct{ x, y T1 }, more ...interface{}) (p, q, r chan<- T10)

func (p *T1) M1()


================================================
FILE: internal/gcimporter/testdata/issue15920.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package p

// The underlying type of Error is the underlying type of error.
// Make sure we can import this again without problems.
type Error error

func F() Error { return nil }


================================================
FILE: internal/gcimporter/testdata/issue20046.go
================================================
// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package p

var V interface {
	M()
}


================================================
FILE: internal/gcimporter/testdata/issue25301.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package issue25301

type (
	A = interface {
		M()
	}
	T interface {
		A
	}
	S struct{}
)

func (S) M() { println("m") }


================================================
FILE: internal/gcimporter/testdata/issue51836/a/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

type T[K any] struct {
}


================================================
FILE: internal/gcimporter/testdata/issue51836/a.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

type T[K any] struct {
}


================================================
FILE: internal/gcimporter/testdata/issue51836/aa.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

import (
	"./a"
)

type T[K any] struct {
	t a.T[K]
}


================================================
FILE: internal/gcimporter/testdata/issue57015.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package issue57015

type E error

type X[T any] struct {}

func F() X[interface {
	E
}] {
	panic(0)
}



================================================
FILE: internal/gcimporter/testdata/issue58296/a/a.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package a

type A int

func (A) f() {}


================================================
FILE: internal/gcimporter/testdata/issue58296/b/b.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package b

import "./a"

type B struct {
	a a.A
}


================================================
FILE: internal/gcimporter/testdata/issue58296/c/c.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package c

import "./b"

type C struct {
	b b.B
}


================================================
FILE: internal/gcimporter/testdata/p.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Input for TestIssue15517

package p

const C = 0

var V int

func F() {}


================================================
FILE: internal/gcimporter/testdata/versions/test.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file is a copy of $GOROOT/src/go/internal/gcimporter/testdata/versions.test.go.

// To create a test case for a new export format version,
// build this package with the latest compiler and store
// the resulting .a file appropriately named in the versions
// directory. The VersionHandling test will pick it up.
//
// In the testdata/versions:
//
// go build -o test_go1.$X_$Y.a test.go
//
// with $X = Go version and $Y = export format version (e.g. 'i', 'u').
//
// Make sure this source is extended such that it exercises
// whatever export format change has taken place.

package test

// Any release before and including Go 1.7 didn't encode
// the package for a blank struct field.
type BlankField struct {
	_ int
}


================================================
FILE: internal/gcimporter/ureader_yes.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Derived from go/internal/gcimporter/ureader.go

package gcimporter

import (
	"fmt"
	"go/token"
	"go/types"
	"sort"

	"golang.org/x/tools/internal/aliases"
	"golang.org/x/tools/internal/pkgbits"
	"golang.org/x/tools/internal/typesinternal"
)

// A pkgReader holds the shared state for reading a unified IR package
// description.
type pkgReader struct {
	pkgbits.PkgDecoder

	fake fakeFileSet

	ctxt    *types.Context
	imports map[string]*types.Package // previously imported packages, indexed by path

	// lazily initialized arrays corresponding to the unified IR
	// PosBase, Pkg, and Type sections, respectively.
	posBases []string // position bases (i.e., file names)
	pkgs     []*types.Package
	typs     []types.Type

	// laterFns holds functions that need to be invoked at the end of
	// import reading.
	laterFns []func()
	// laterFors is used in case of 'type A B' to ensure that B is processed before A.
	laterFors map[types.Type]int

	// ifaces holds a list of constructed Interfaces, which need to have
	// Complete called after importing is done.
	ifaces []*types.Interface
}

// later adds a function to be invoked at the end of import reading.
func (pr *pkgReader) later(fn func()) {
	pr.laterFns = append(pr.laterFns, fn)
}

// See cmd/compile/internal/noder.derivedInfo.
type derivedInfo struct {
	idx pkgbits.Index
}

// See cmd/compile/internal/noder.typeInfo.
type typeInfo struct {
	idx     pkgbits.Index
	derived bool
}

func UImportData(fset *token.FileSet, imports map[string]*types.Package, data []byte, path string) (_ int, pkg *types.Package, err error) {
	if !debug {
		defer func() {
			if x := recover(); x != nil {
				err = fmt.Errorf("internal error in importing %q (%v); please report an issue", path, x)
			}
		}()
	}

	s := string(data)
	input := pkgbits.NewPkgDecoder(path, s)
	pkg = readUnifiedPackage(fset, nil, imports, input)
	return
}

// laterFor adds a function to be invoked at the end of import reading, and records the type that function is finishing.
func (pr *pkgReader) laterFor(t types.Type, fn func()) {
	if pr.laterFors == nil {
		pr.laterFors = make(map[types.Type]int)
	}
	pr.laterFors[t] = len(pr.laterFns)
	pr.laterFns = append(pr.laterFns, fn)
}

// readUnifiedPackage reads a package description from the given
// unified IR export data decoder.
func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[string]*types.Package, input pkgbits.PkgDecoder) *types.Package {
	pr := pkgReader{
		PkgDecoder: input,

		fake: fakeFileSet{
			fset:  fset,
			files: make(map[string]*fileInfo),
		},

		ctxt:    ctxt,
		imports: imports,

		posBases: make([]string, input.NumElems(pkgbits.RelocPosBase)),
		pkgs:     make([]*types.Package, input.NumElems(pkgbits.RelocPkg)),
		typs:     make([]types.Type, input.NumElems(pkgbits.RelocType)),
	}
	defer pr.fake.setLines()

	r := pr.newReader(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)
	pkg := r.pkg()
	if r.Version().Has(pkgbits.HasInit) {
		r.Bool()
	}

	for i, n := 0, r.Len(); i < n; i++ {
		// As if r.obj(), but avoiding the Scope.Lookup call,
		// to avoid eager loading of imports.
		r.Sync(pkgbits.SyncObject)
		if r.Version().Has(pkgbits.DerivedFuncInstance) {
			assert(!r.Bool())
		}
		r.p.objIdx(r.Reloc(pkgbits.RelocObj))
		assert(r.Len() == 0)
	}

	r.Sync(pkgbits.SyncEOF)

	for _, fn := range pr.laterFns {
		fn()
	}

	for _, iface := range pr.ifaces {
		iface.Complete()
	}

	// Imports() of pkg are all of the transitive packages that were loaded.
	var imps []*types.Package
	for _, imp := range pr.pkgs {
		if imp != nil && imp != pkg {
			imps = append(imps, imp)
		}
	}
	sort.Sort(byPath(imps))
	pkg.SetImports(imps)

	pkg.MarkComplete()
	return pkg
}

// A reader holds the state for reading a single unified IR element
// within a package.
type reader struct {
	pkgbits.Decoder

	p *pkgReader

	dict *readerDict
}

// A readerDict holds the state for type parameters that parameterize
// the current unified IR element.
type readerDict struct {
	// bounds is a slice of typeInfos corresponding to the underlying
	// bounds of the element's type parameters.
	bounds []typeInfo

	// tparams is a slice of the constructed TypeParams for the element.
	tparams []*types.TypeParam

	// derived is a slice of types derived from tparams, which may be
	// instantiated while reading the current element.
	derived      []derivedInfo
	derivedTypes []types.Type // lazily instantiated from derived
}

func (pr *pkgReader) newReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
	return &reader{
		Decoder: pr.NewDecoder(k, idx, marker),
		p:       pr,
	}
}

func (pr *pkgReader) tempReader(k pkgbits.RelocKind, idx pkgbits.Index, marker pkgbits.SyncMarker) *reader {
	return &reader{
		Decoder: pr.TempDecoder(k, idx, marker),
		p:       pr,
	}
}

func (pr *pkgReader) retireReader(r *reader) {
	pr.RetireDecoder(&r.Decoder)
}

// @@@ Positions

func (r *reader) pos() token.Pos {
	r.Sync(pkgbits.SyncPos)
	if !r.Bool() {
		return token.NoPos
	}

	// TODO(mdempsky): Delta encoding.
	posBase := r.posBase()
	line := r.Uint()
	col := r.Uint()
	return r.p.fake.pos(posBase, int(line), int(col))
}

func (r *reader) posBase() string {
	return r.p.posBaseIdx(r.Reloc(pkgbits.RelocPosBase))
}

func (pr *pkgReader) posBaseIdx(idx pkgbits.Index) string {
	if b := pr.posBases[idx]; b != "" {
		return b
	}

	var filename string
	{
		r := pr.tempReader(pkgbits.RelocPosBase, idx, pkgbits.SyncPosBase)

		// Within types2, position bases have a lot more details (e.g.,
		// keeping track of where //line directives appeared exactly).
		//
		// For go/types, we just track the file name.

		filename = r.String()

		if r.Bool() { // file base
			// Was: "b = token.NewTrimmedFileBase(filename, true)"
		} else { // line base
			pos := r.pos()
			line := r.Uint()
			col := r.Uint()

			// Was: "b = token.NewLineBase(pos, filename, true, line, col)"
			_, _, _ = pos, line, col
		}
		pr.retireReader(r)
	}
	b := filename
	pr.posBases[idx] = b
	return b
}

// @@@ Packages

func (r *reader) pkg() *types.Package {
	r.Sync(pkgbits.SyncPkg)
	return r.p.pkgIdx(r.Reloc(pkgbits.RelocPkg))
}

func (pr *pkgReader) pkgIdx(idx pkgbits.Index) *types.Package {
	// TODO(mdempsky): Consider using some non-nil pointer to indicate
	// the universe scope, so we don't need to keep re-reading it.
	if pkg := pr.pkgs[idx]; pkg != nil {
		return pkg
	}

	pkg := pr.newReader(pkgbits.RelocPkg, idx, pkgbits.SyncPkgDef).doPkg()
	pr.pkgs[idx] = pkg
	return pkg
}

func (r *reader) doPkg() *types.Package {
	path := r.String()
	switch path {
	// cmd/compile emits path="main" for main packages because
	// that's the linker symbol prefix it used; but we need
	// the package's path as it would be reported by go list,
	// hence "main" below.
	// See test at go/packages.TestMainPackagePathInModeTypes.
	case "", "main":
		path = r.p.PkgPath()
	case "builtin":
		return nil // universe
	case "unsafe":
		return types.Unsafe
	}

	if pkg := r.p.imports[path]; pkg != nil {
		return pkg
	}

	name := r.String()

	pkg := types.NewPackage(path, name)
	r.p.imports[path] = pkg

	return pkg
}

// @@@ Types

func (r *reader) typ() types.Type {
	return r.p.typIdx(r.typInfo(), r.dict)
}

func (r *reader) typInfo() typeInfo {
	r.Sync(pkgbits.SyncType)
	if r.Bool() {
		return typeInfo{idx: pkgbits.Index(r.Len()), derived: true}
	}
	return typeInfo{idx: r.Reloc(pkgbits.RelocType), derived: false}
}

func (pr *pkgReader) typIdx(info typeInfo, dict *readerDict) types.Type {
	idx := info.idx
	var where *types.Type
	if info.derived {
		where = &dict.derivedTypes[idx]
		idx = dict.derived[idx].idx
	} else {
		where = &pr.typs[idx]
	}

	if typ := *where; typ != nil {
		return typ
	}

	var typ types.Type
	{
		r := pr.tempReader(pkgbits.RelocType, idx, pkgbits.SyncTypeIdx)
		r.dict = dict

		typ = r.doTyp()
		assert(typ != nil)
		pr.retireReader(r)
	}
	// See comment in pkgReader.typIdx explaining how this happens.
	if prev := *where; prev != nil {
		return prev
	}

	*where = typ
	return typ
}

func (r *reader) doTyp() (res types.Type) {
	switch tag := pkgbits.CodeType(r.Code(pkgbits.SyncType)); tag {
	default:
		errorf("unhandled type tag: %v", tag)
		panic("unreachable")

	case pkgbits.TypeBasic:
		return types.Typ[r.Len()]

	case pkgbits.TypeNamed:
		obj, targs := r.obj()
		name := obj.(*types.TypeName)
		if len(targs) != 0 {
			t, _ := types.Instantiate(r.p.ctxt, name.Type(), targs, false)
			return t
		}
		return name.Type()

	case pkgbits.TypeTypeParam:
		return r.dict.tparams[r.Len()]

	case pkgbits.TypeArray:
		len := int64(r.Uint64())
		return types.NewArray(r.typ(), len)
	case pkgbits.TypeChan:
		dir := types.ChanDir(r.Len())
		return types.NewChan(dir, r.typ())
	case pkgbits.TypeMap:
		return types.NewMap(r.typ(), r.typ())
	case pkgbits.TypePointer:
		return types.NewPointer(r.typ())
	case pkgbits.TypeSignature:
		return r.signature(nil, nil, nil)
	case pkgbits.TypeSlice:
		return types.NewSlice(r.typ())
	case pkgbits.TypeStruct:
		return r.structType()
	case pkgbits.TypeInterface:
		return r.interfaceType()
	case pkgbits.TypeUnion:
		return r.unionType()
	}
}

func (r *reader) structType() *types.Struct {
	fields := make([]*types.Var, r.Len())
	var tags []string
	for i := range fields {
		pos := r.pos()
		pkg, name := r.selector()
		ftyp := r.typ()
		tag := r.String()
		embedded := r.Bool()

		fields[i] = types.NewField(pos, pkg, name, ftyp, embedded)
		if tag != "" {
			for len(tags) < i {
				tags = append(tags, "")
			}
			tags = append(tags, tag)
		}
	}
	return types.NewStruct(fields, tags)
}

func (r *reader) unionType() *types.Union {
	terms := make([]*types.Term, r.Len())
	for i := range terms {
		terms[i] = types.NewTerm(r.Bool(), r.typ())
	}
	return types.NewUnion(terms)
}

func (r *reader) interfaceType() *types.Interface {
	methods := make([]*types.Func, r.Len())
	embeddeds := make([]types.Type, r.Len())
	implicit := len(methods) == 0 && len(embeddeds) == 1 && r.Bool()

	for i := range methods {
		pos := r.pos()
		pkg, name := r.selector()
		mtyp := r.signature(nil, nil, nil)
		methods[i] = types.NewFunc(pos, pkg, name, mtyp)
	}

	for i := range embeddeds {
		embeddeds[i] = r.typ()
	}

	iface := types.NewInterfaceType(methods, embeddeds)
	if implicit {
		iface.MarkImplicit()
	}

	// We need to call iface.Complete(), but if there are any embedded
	// defined types, then we may not have set their underlying
	// interface type yet. So we need to defer calling Complete until
	// after we've called SetUnderlying everywhere.
	//
	// TODO(mdempsky): After CL 424876 lands, it should be safe to call
	// iface.Complete() immediately.
	r.p.ifaces = append(r.p.ifaces, iface)

	return iface
}

func (r *reader) signature(recv *types.Var, rtparams, tparams []*types.TypeParam) *types.Signature {
	r.Sync(pkgbits.SyncSignature)

	params := r.params()
	results := r.params()
	variadic := r.Bool()

	return types.NewSignatureType(recv, rtparams, tparams, params, results, variadic)
}

func (r *reader) params() *types.Tuple {
	r.Sync(pkgbits.SyncParams)

	params := make([]*types.Var, r.Len())
	for i := range params {
		params[i] = r.param()
	}

	return types.NewTuple(params...)
}

func (r *reader) param() *types.Var {
	r.Sync(pkgbits.SyncParam)

	pos := r.pos()
	pkg, name := r.localIdent()
	typ := r.typ()

	return types.NewParam(pos, pkg, name, typ)
}

// @@@ Objects

func (r *reader) obj() (types.Object, []types.Type) {
	r.Sync(pkgbits.SyncObject)

	if r.Version().Has(pkgbits.DerivedFuncInstance) {
		assert(!r.Bool())
	}

	pkg, name := r.p.objIdx(r.Reloc(pkgbits.RelocObj))
	obj := pkgScope(pkg).Lookup(name)

	targs := make([]types.Type, r.Len())
	for i := range targs {
		targs[i] = r.typ()
	}

	return obj, targs
}

func (pr *pkgReader) objIdx(idx pkgbits.Index) (*types.Package, string) {

	var objPkg *types.Package
	var objName string
	var tag pkgbits.CodeObj
	{
		rname := pr.tempReader(pkgbits.RelocName, idx, pkgbits.SyncObject1)

		objPkg, objName = rname.qualifiedIdent()
		assert(objName != "")

		tag = pkgbits.CodeObj(rname.Code(pkgbits.SyncCodeObj))
		pr.retireReader(rname)
	}

	if tag == pkgbits.ObjStub {
		assert(objPkg == nil || objPkg == types.Unsafe)
		return objPkg, objName
	}

	// Ignore local types promoted to global scope (#55110).
	if _, suffix := splitVargenSuffix(objName); suffix != "" {
		return objPkg, objName
	}

	if objPkg.Scope().Lookup(objName) == nil {
		dict := pr.objDictIdx(idx)

		r := pr.newReader(pkgbits.RelocObj, idx, pkgbits.SyncObject1)
		r.dict = dict

		declare := func(obj types.Object) {
			objPkg.Scope().Insert(obj)
		}

		switch tag {
		default:
			panic("weird")

		case pkgbits.ObjAlias:
			pos := r.pos()
			var tparams []*types.TypeParam
			if r.Version().Has(pkgbits.AliasTypeParamNames) {
				tparams = r.typeParamNames()
			}
			typ := r.typ()
			declare(aliases.New(pos, objPkg, objName, typ, tparams))

		case pkgbits.ObjConst:
			pos := r.pos()
			typ := r.typ()
			val := r.Value()
			declare(types.NewConst(pos, objPkg, objName, typ, val))

		case pkgbits.ObjFunc:
			pos := r.pos()
			tparams := r.typeParamNames()
			sig := r.signature(nil, nil, tparams)
			declare(types.NewFunc(pos, objPkg, objName, sig))

		case pkgbits.ObjType:
			pos := r.pos()

			obj := types.NewTypeName(pos, objPkg, objName, nil)
			named := types.NewNamed(obj, nil, nil)
			declare(obj)

			named.SetTypeParams(r.typeParamNames())

			setUnderlying := func(underlying types.Type) {
				// If the underlying type is an interface, we need to
				// duplicate its methods so we can replace the receiver
				// parameter's type (#49906).
				if iface, ok := types.Unalias(underlying).(*types.Interface); ok && iface.NumExplicitMethods() != 0 {
					methods := make([]*types.Func, iface.NumExplicitMethods())
					for i := range methods {
						fn := iface.ExplicitMethod(i)
						sig := fn.Type().(*types.Signature)

						recv := types.NewVar(fn.Pos(), fn.Pkg(), "", named)
						typesinternal.SetVarKind(recv, typesinternal.RecvVar)
						methods[i] = types.NewFunc(fn.Pos(), fn.Pkg(), fn.Name(), types.NewSignatureType(recv, nil, nil, sig.Params(), sig.Results(), sig.Variadic()))
					}

					embeds := make([]types.Type, iface.NumEmbeddeds())
					for i := range embeds {
						embeds[i] = iface.EmbeddedType(i)
					}

					newIface := types.NewInterfaceType(methods, embeds)
					r.p.ifaces = append(r.p.ifaces, newIface)
					underlying = newIface
				}

				named.SetUnderlying(underlying)
			}

			// Since go.dev/cl/455279, we can assume rhs.Underlying() will
			// always be non-nil. However, to temporarily support users of
			// older snapshot releases, we continue to fallback to the old
			// behavior for now.
			//
			// TODO(mdempsky): Remove fallback code and simplify after
			// allowing time for snapshot users to upgrade.
			rhs := r.typ()
			if underlying := rhs.Underlying(); underlying != nil {
				setUnderlying(underlying)
			} else {
				pk := r.p
				pk.laterFor(named, func() {
					// First be sure that the rhs is initialized, if it needs to be initialized.
					delete(pk.laterFors, named) // prevent cycles
					if i, ok := pk.laterFors[rhs]; ok {
						f := pk.laterFns[i]
						pk.laterFns[i] = func() {} // function is running now, so replace it with a no-op
						f()                        // initialize RHS
					}
					setUnderlying(rhs.Underlying())
				})
			}

			for i, n := 0, r.Len(); i < n; i++ {
				named.AddMethod(r.method())
			}

		case pkgbits.ObjVar:
			pos := r.pos()
			typ := r.typ()
			v := types.NewVar(pos, objPkg, objName, typ)
			typesinternal.SetVarKind(v, typesinternal.PackageVar)
			declare(v)
		}
	}

	return objPkg, objName
}

func (pr *pkgReader) objDictIdx(idx pkgbits.Index) *readerDict {

	var dict readerDict

	{
		r := pr.tempReader(pkgbits.RelocObjDict, idx, pkgbits.SyncObject1)
		if implicits := r.Len(); implicits != 0 {
			errorf("unexpected object with %v implicit type parameter(s)", implicits)
		}

		dict.bounds = make([]typeInfo, r.Len())
		for i := range dict.bounds {
			dict.bounds[i] = r.typInfo()
		}

		dict.derived = make([]derivedInfo, r.Len())
		dict.derivedTypes = make([]types.Type, len(dict.derived))
		for i := range dict.derived {
			dict.derived[i] = derivedInfo{idx: r.Reloc(pkgbits.RelocType)}
			if r.Version().Has(pkgbits.DerivedInfoNeeded) {
				assert(!r.Bool())
			}
		}

		pr.retireReader(r)
	}
	// function references follow, but reader doesn't need those

	return &dict
}

func (r *reader) typeParamNames() []*types.TypeParam {
	r.Sync(pkgbits.SyncTypeParamNames)

	// Note: This code assumes it only processes objects without
	// implement type parameters. This is currently fine, because
	// reader is only used to read in exported declarations, which are
	// always package scoped.

	if len(r.dict.bounds) == 0 {
		return nil
	}

	// Careful: Type parameter lists may have cycles. To allow for this,
	// we construct the type parameter list in two passes: first we
	// create all the TypeNames and TypeParams, then we construct and
	// set the bound type.

	r.dict.tparams = make([]*types.TypeParam, len(r.dict.bounds))
	for i := range r.dict.bounds {
		pos := r.pos()
		pkg, name := r.localIdent()

		tname := types.NewTypeName(pos, pkg, name, nil)
		r.dict.tparams[i] = types.NewTypeParam(tname, nil)
	}

	typs := make([]types.Type, len(r.dict.bounds))
	for i, bound := range r.dict.bounds {
		typs[i] = r.p.typIdx(bound, r.dict)
	}

	// TODO(mdempsky): This is subtle, elaborate further.
	//
	// We have to save tparams outside of the closure, because
	// typeParamNames() can be called multiple times with the same
	// dictionary instance.
	//
	// Also, this needs to happen later to make sure SetUnderlying has
	// been called.
	//
	// TODO(mdempsky): Is it safe to have a single "later" slice or do
	// we need to have multiple passes? See comments on CL 386002 and
	// go.dev/issue/52104.
	tparams := r.dict.tparams
	r.p.later(func() {
		for i, typ := range typs {
			tparams[i].SetConstraint(typ)
		}
	})

	return r.dict.tparams
}

func (r *reader) method() *types.Func {
	r.Sync(pkgbits.SyncMethod)
	pos := r.pos()
	pkg, name := r.selector()

	rparams := r.typeParamNames()
	sig := r.signature(r.param(), rparams, nil)

	_ = r.pos() // TODO(mdempsky): Remove; this is a hacker for linker.go.
	return types.NewFunc(pos, pkg, name, sig)
}

func (r *reader) qualifiedIdent() (*types.Package, string) { return r.ident(pkgbits.SyncSym) }
func (r *reader) localIdent() (*types.Package, string)     { return r.ident(pkgbits.SyncLocalIdent) }
func (r *reader) selector() (*types.Package, string)       { return r.ident(pkgbits.SyncSelector) }

func (r *reader) ident(marker pkgbits.SyncMarker) (*types.Package, string) {
	r.Sync(marker)
	return r.pkg(), r.String()
}

// pkgScope returns pkg.Scope().
// If pkg is nil, it returns types.Universe instead.
//
// TODO(mdempsky): Remove after x/tools can depend on Go 1.19.
func pkgScope(pkg *types.Package) *types.Scope {
	if pkg != nil {
		return pkg.Scope()
	}
	return types.Universe
}

// See cmd/compile/internal/types.SplitVargenSuffix.
func splitVargenSuffix(name string) (base, suffix string) {
	i := len(name)
	for i > 0 && name[i-1] >= '0' && name[i-1] <= '9' {
		i--
	}
	const dot = "·"
	if i >= len(dot) && name[i-len(dot):i] == dot {
		i -= len(dot)
		return name[:i], name[i:]
	}
	return name, ""
}


================================================
FILE: internal/gocommand/invoke.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gocommand is a helper for calling the go command.
package gocommand

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"sync"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/keys"
	"golang.org/x/tools/internal/event/label"
)

// A Runner will run go command invocations and serialize
// them if it sees a concurrency error.
type Runner struct {
	// once guards the runner initialization.
	once sync.Once

	// inFlight tracks available workers.
	inFlight chan struct{}

	// serialized guards the ability to run a go command serially,
	// to avoid deadlocks when claiming workers.
	serialized chan struct{}
}

const maxInFlight = 10

func (runner *Runner) initialize() {
	runner.once.Do(func() {
		runner.inFlight = make(chan struct{}, maxInFlight)
		runner.serialized = make(chan struct{}, 1)
	})
}

// 1.13: go: updates to go.mod needed, but contents have changed
// 1.14: go: updating go.mod: existing contents have changed since last read
var modConcurrencyError = regexp.MustCompile(`go:.*go.mod.*contents have changed`)

// event keys for go command invocations
var (
	verb      = keys.NewString("verb", "go command verb")
	directory = keys.NewString("directory", "")
)

func invLabels(inv Invocation) []label.Label {
	return []label.Label{verb.Of(inv.Verb), directory.Of(inv.WorkingDir)}
}

// Run is a convenience wrapper around RunRaw.
// It returns only stdout and a "friendly" error.
func (runner *Runner) Run(ctx context.Context, inv Invocation) (*bytes.Buffer, error) {
	ctx, done := event.Start(ctx, "gocommand.Runner.Run", invLabels(inv)...)
	defer done()

	stdout, _, friendly, _ := runner.RunRaw(ctx, inv)
	return stdout, friendly
}

// RunPiped runs the invocation serially, always waiting for any concurrent
// invocations to complete first.
func (runner *Runner) RunPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) error {
	ctx, done := event.Start(ctx, "gocommand.Runner.RunPiped", invLabels(inv)...)
	defer done()

	_, err := runner.runPiped(ctx, inv, stdout, stderr)
	return err
}

// RunRaw runs the invocation, serializing requests only if they fight over
// go.mod changes.
// Postcondition: both error results have same nilness.
func (runner *Runner) RunRaw(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
	ctx, done := event.Start(ctx, "gocommand.Runner.RunRaw", invLabels(inv)...)
	defer done()
	// Make sure the runner is always initialized.
	runner.initialize()

	// First, try to run the go command concurrently.
	stdout, stderr, friendlyErr, err := runner.runConcurrent(ctx, inv)

	// If we encounter a load concurrency error, we need to retry serially.
	if friendlyErr != nil && modConcurrencyError.MatchString(friendlyErr.Error()) {
		event.Error(ctx, "Load concurrency error, will retry serially", err)

		// Run serially by calling runPiped.
		stdout.Reset()
		stderr.Reset()
		friendlyErr, err = runner.runPiped(ctx, inv, stdout, stderr)
	}

	return stdout, stderr, friendlyErr, err
}

// Postcondition: both error results have same nilness.
func (runner *Runner) runConcurrent(ctx context.Context, inv Invocation) (*bytes.Buffer, *bytes.Buffer, error, error) {
	// Wait for 1 worker to become available.
	select {
	case <-ctx.Done():
		return nil, nil, ctx.Err(), ctx.Err()
	case runner.inFlight <- struct{}{}:
		defer func() { <-runner.inFlight }()
	}

	stdout, stderr := &bytes.Buffer{}, &bytes.Buffer{}
	friendlyErr, err := inv.runWithFriendlyError(ctx, stdout, stderr)
	return stdout, stderr, friendlyErr, err
}

// Postcondition: both error results have same nilness.
func (runner *Runner) runPiped(ctx context.Context, inv Invocation, stdout, stderr io.Writer) (error, error) {
	// Make sure the runner is always initialized.
	runner.initialize()

	// Acquire the serialization lock. This avoids deadlocks between two
	// runPiped commands.
	select {
	case <-ctx.Done():
		return ctx.Err(), ctx.Err()
	case runner.serialized <- struct{}{}:
		defer func() { <-runner.serialized }()
	}

	// Wait for all in-progress go commands to return before proceeding,
	// to avoid load concurrency errors.
	for range maxInFlight {
		select {
		case <-ctx.Done():
			return ctx.Err(), ctx.Err()
		case runner.inFlight <- struct{}{}:
			// Make sure we always "return" any workers we took.
			defer func() { <-runner.inFlight }()
		}
	}

	return inv.runWithFriendlyError(ctx, stdout, stderr)
}

// An Invocation represents a call to the go command.
type Invocation struct {
	Verb       string
	Args       []string
	BuildFlags []string

	// If ModFlag is set, the go command is invoked with -mod=ModFlag.
	// TODO(rfindley): remove, in favor of Args.
	ModFlag string

	// If ModFile is set, the go command is invoked with -modfile=ModFile.
	// TODO(rfindley): remove, in favor of Args.
	ModFile string

	// Overlay is the name of the JSON overlay file that describes
	// unsaved editor buffers; see [WriteOverlays].
	// If set, the go command is invoked with -overlay=Overlay.
	// TODO(rfindley): remove, in favor of Args.
	Overlay string

	// If CleanEnv is set, the invocation will run only with the environment
	// in Env, not starting with os.Environ.
	CleanEnv   bool
	Env        []string
	WorkingDir string
	Logf       func(format string, args ...any)
}

// Postcondition: both error results have same nilness.
func (i *Invocation) runWithFriendlyError(ctx context.Context, stdout, stderr io.Writer) (friendlyError error, rawError error) {
	rawError = i.run(ctx, stdout, stderr)
	if rawError != nil {
		friendlyError = rawError
		// Check for 'go' executable not being found.
		if ee, ok := rawError.(*exec.Error); ok && ee.Err == exec.ErrNotFound {
			friendlyError = fmt.Errorf("go command required, not found: %v", ee)
		}
		if ctx.Err() != nil {
			friendlyError = ctx.Err()
		}
		friendlyError = fmt.Errorf("err: %v: stderr: %s", friendlyError, stderr)
	}
	return
}

// logf logs if i.Logf is non-nil.
func (i *Invocation) logf(format string, args ...any) {
	if i.Logf != nil {
		i.Logf(format, args...)
	}
}

func (i *Invocation) run(ctx context.Context, stdout, stderr io.Writer) error {
	goArgs := []string{i.Verb}

	appendModFile := func() {
		if i.ModFile != "" {
			goArgs = append(goArgs, "-modfile="+i.ModFile)
		}
	}
	appendModFlag := func() {
		if i.ModFlag != "" {
			goArgs = append(goArgs, "-mod="+i.ModFlag)
		}
	}
	appendOverlayFlag := func() {
		if i.Overlay != "" {
			goArgs = append(goArgs, "-overlay="+i.Overlay)
		}
	}

	switch i.Verb {
	case "env", "version":
		goArgs = append(goArgs, i.Args...)
	case "mod":
		// mod needs the sub-verb before flags.
		goArgs = append(goArgs, i.Args[0])
		appendModFile()
		goArgs = append(goArgs, i.Args[1:]...)
	case "get":
		goArgs = append(goArgs, i.BuildFlags...)
		appendModFile()
		goArgs = append(goArgs, i.Args...)

	default: // notably list and build.
		goArgs = append(goArgs, i.BuildFlags...)
		appendModFile()
		appendModFlag()
		appendOverlayFlag()
		goArgs = append(goArgs, i.Args...)
	}
	cmd := exec.Command("go", goArgs...)
	cmd.Stdout = stdout
	cmd.Stderr = stderr

	// https://go.dev/issue/59541: don't wait forever copying stderr
	// after the command has exited.
	// After CL 484741 we copy stdout manually, so we we'll stop reading that as
	// soon as ctx is done. However, we also don't want to wait around forever
	// for stderr. Give a much-longer-than-reasonable delay and then assume that
	// something has wedged in the kernel or runtime.
	cmd.WaitDelay = 30 * time.Second

	// The cwd gets resolved to the real path. On Darwin, where
	// /tmp is a symlink, this breaks anything that expects the
	// working directory to keep the original path, including the
	// go command when dealing with modules.
	//
	// os.Getwd has a special feature where if the cwd and the PWD
	// are the same node then it trusts the PWD, so by setting it
	// in the env for the child process we fix up all the paths
	// returned by the go command.
	if !i.CleanEnv {
		cmd.Env = os.Environ()
	}
	cmd.Env = append(cmd.Env, i.Env...)
	if i.WorkingDir != "" {
		cmd.Env = append(cmd.Env, "PWD="+i.WorkingDir)
		cmd.Dir = i.WorkingDir
	}

	debugStr := cmdDebugStr(cmd)
	i.logf("starting %v", debugStr)
	start := time.Now()
	defer func() {
		i.logf("%s for %v", time.Since(start), debugStr)
	}()

	return runCmdContext(ctx, cmd)
}

// DebugHangingGoCommands may be set by tests to enable additional
// instrumentation (including panics) for debugging hanging Go commands.
//
// See golang/go#54461 for details.
var DebugHangingGoCommands = false

// runCmdContext is like exec.CommandContext except it sends os.Interrupt
// before os.Kill.
func runCmdContext(ctx context.Context, cmd *exec.Cmd) (err error) {
	// If cmd.Stdout is not an *os.File, the exec package will create a pipe and
	// copy it to the Writer in a goroutine until the process has finished and
	// either the pipe reaches EOF or command's WaitDelay expires.
	//
	// However, the output from 'go list' can be quite large, and we don't want to
	// keep reading (and allocating buffers) if we've already decided we don't
	// care about the output. We don't want to wait for the process to finish, and
	// we don't wait to wait for the WaitDelay to expire either.
	//
	// Instead, if cmd.Stdout requires a copying goroutine we explicitly replace
	// it with a pipe (which is an *os.File), which we can close in order to stop
	// copying output as soon as we realize we don't care about it.
	var stdoutW *os.File
	if cmd.Stdout != nil {
		if _, ok := cmd.Stdout.(*os.File); !ok {
			var stdoutR *os.File
			stdoutR, stdoutW, err = os.Pipe()
			if err != nil {
				return err
			}
			prevStdout := cmd.Stdout
			cmd.Stdout = stdoutW

			stdoutErr := make(chan error, 1)
			go func() {
				_, err := io.Copy(prevStdout, stdoutR)
				if err != nil {
					err = fmt.Errorf("copying stdout: %w", err)
				}
				stdoutErr <- err
			}()
			defer func() {
				// We started a goroutine to copy a stdout pipe.
				// Wait for it to finish, or terminate it if need be.
				var err2 error
				select {
				case err2 = <-stdoutErr:
					stdoutR.Close()
				case <-ctx.Done():
					stdoutR.Close()
					// Per https://pkg.go.dev/os#File.Close, the call to stdoutR.Close
					// should cause the Read call in io.Copy to unblock and return
					// immediately, but we still need to receive from stdoutErr to confirm
					// that it has happened.
					<-stdoutErr
					err2 = ctx.Err()
				}
				if err == nil {
					err = err2
				}
			}()

			// Per https://pkg.go.dev/os/exec#Cmd, “If Stdout and Stderr are the
			// same writer, and have a type that can be compared with ==, at most
			// one goroutine at a time will call Write.”
			//
			// Since we're starting a goroutine that writes to cmd.Stdout, we must
			// also update cmd.Stderr so that it still holds.
			func() {
				defer func() { recover() }()
				if cmd.Stderr == prevStdout {
					cmd.Stderr = cmd.Stdout
				}
			}()
		}
	}

	startTime := time.Now()
	err = cmd.Start()
	if stdoutW != nil {
		// The child process has inherited the pipe file,
		// so close the copy held in this process.
		stdoutW.Close()
		stdoutW = nil
	}
	if err != nil {
		return err
	}

	resChan := make(chan error, 1)
	go func() {
		resChan <- cmd.Wait()
	}()

	// If we're interested in debugging hanging Go commands, stop waiting after a
	// minute and panic with interesting information.
	debug := DebugHangingGoCommands
	if debug {
		timer := time.NewTimer(1 * time.Minute)
		defer timer.Stop()
		select {
		case err := <-resChan:
			return err
		case <-timer.C:
			// HandleHangingGoCommand terminates this process.
			// Pass off resChan in case we can collect the command error.
			handleHangingGoCommand(startTime, cmd, resChan)
		case <-ctx.Done():
		}
	} else {
		select {
		case err := <-resChan:
			return err
		case <-ctx.Done():
		}
	}

	// Cancelled. Interrupt and see if it ends voluntarily.
	if err := cmd.Process.Signal(os.Interrupt); err == nil {
		// (We used to wait only 1s but this proved
		// fragile on loaded builder machines.)
		timer := time.NewTimer(5 * time.Second)
		defer timer.Stop()
		select {
		case err := <-resChan:
			return err
		case <-timer.C:
		}
	}

	// Didn't shut down in response to interrupt. Kill it hard.
	if err := cmd.Process.Kill(); err != nil && !errors.Is(err, os.ErrProcessDone) && debug {
		log.Printf("error killing the Go command: %v", err)
	}

	return <-resChan
}

// handleHangingGoCommand outputs debugging information to help diagnose the
// cause of a hanging Go command, and then exits with log.Fatalf.
func handleHangingGoCommand(start time.Time, cmd *exec.Cmd, resChan chan error) {
	switch runtime.GOOS {
	case "linux", "darwin", "freebsd", "netbsd", "openbsd":
		fmt.Fprintln(os.Stderr, `DETECTED A HANGING GO COMMAND

			The gopls test runner has detected a hanging go command. In order to debug
			this, the output of ps and lsof/fstat is printed below.

			See golang/go#54461 for more details.`)

		fmt.Fprintln(os.Stderr, "\nps axo ppid,pid,command:")
		fmt.Fprintln(os.Stderr, "-------------------------")
		psCmd := exec.Command("ps", "axo", "ppid,pid,command")
		psCmd.Stdout = os.Stderr
		psCmd.Stderr = os.Stderr
		if err := psCmd.Run(); err != nil {
			log.Printf("Handling hanging Go command: running ps: %v", err)
		}

		listFiles := "lsof"
		if runtime.GOOS == "freebsd" || runtime.GOOS == "netbsd" {
			listFiles = "fstat"
		}

		fmt.Fprintln(os.Stderr, "\n"+listFiles+":")
		fmt.Fprintln(os.Stderr, "-----")
		listFilesCmd := exec.Command(listFiles)
		listFilesCmd.Stdout = os.Stderr
		listFilesCmd.Stderr = os.Stderr
		if err := listFilesCmd.Run(); err != nil {
			log.Printf("Handling hanging Go command: running %s: %v", listFiles, err)
		}
		// Try to extract information about the slow go process by issuing a SIGQUIT.
		if err := cmd.Process.Signal(sigStuckProcess); err == nil {
			select {
			case err := <-resChan:
				stderr := "not a bytes.Buffer"
				if buf, _ := cmd.Stderr.(*bytes.Buffer); buf != nil {
					stderr = buf.String()
				}
				log.Printf("Quit hanging go command:\n\terr:%v\n\tstderr:\n%v\n\n", err, stderr)
			case <-time.After(5 * time.Second):
			}
		} else {
			log.Printf("Sending signal %d to hanging go command: %v", sigStuckProcess, err)
		}
	}
	log.Fatalf("detected hanging go command (golang/go#54461); waited %s\n\tcommand:%s\n\tpid:%d", time.Since(start), cmd, cmd.Process.Pid)
}

func cmdDebugStr(cmd *exec.Cmd) string {
	env := make(map[string]string)
	for _, kv := range cmd.Env {
		split := strings.SplitN(kv, "=", 2)
		if len(split) == 2 {
			k, v := split[0], split[1]
			env[k] = v
		}
	}

	var args []string
	for _, arg := range cmd.Args {
		quoted := strconv.Quote(arg)
		if quoted[1:len(quoted)-1] != arg || strings.Contains(arg, " ") {
			args = append(args, quoted)
		} else {
			args = append(args, arg)
		}
	}
	return fmt.Sprintf("GOROOT=%v GOPATH=%v GO111MODULE=%v GOPROXY=%v PWD=%v %v", env["GOROOT"], env["GOPATH"], env["GO111MODULE"], env["GOPROXY"], env["PWD"], strings.Join(args, " "))
}

// WriteOverlays writes each value in the overlay (see the Overlay
// field of go/packages.Config) to a temporary file and returns the name
// of a JSON file describing the mapping that is suitable for the "go
// list -overlay" flag.
//
// On success, the caller must call the cleanup function exactly once
// when the files are no longer needed.
func WriteOverlays(overlay map[string][]byte) (filename string, cleanup func(), err error) {
	// Do nothing if there are no overlays in the config.
	if len(overlay) == 0 {
		return "", func() {}, nil
	}

	dir, err := os.MkdirTemp("", "gocommand-*")
	if err != nil {
		return "", nil, err
	}

	// The caller must clean up this directory,
	// unless this function returns an error.
	// (The cleanup operand of each return
	// statement below is ignored.)
	defer func() {
		cleanup = func() {
			os.RemoveAll(dir)
		}
		if err != nil {
			cleanup()
			cleanup = nil
		}
	}()

	// Write each map entry to a temporary file.
	overlays := make(map[string]string)
	for k, v := range overlay {
		// Use a unique basename for each file (001-foo.go),
		// to avoid creating nested directories.
		base := fmt.Sprintf("%d-%s", 1+len(overlays), filepath.Base(k))
		filename := filepath.Join(dir, base)
		err := os.WriteFile(filename, v, 0666)
		if err != nil {
			return "", nil, err
		}
		overlays[k] = filename
	}

	// Write the JSON overlay file that maps logical file names to temp files.
	//
	// OverlayJSON is the format overlay files are expected to be in.
	// The Replace map maps from overlaid paths to replacement paths:
	// the Go command will forward all reads trying to open
	// each overlaid path to its replacement path, or consider the overlaid
	// path not to exist if the replacement path is empty.
	//
	// From golang/go#39958.
	type OverlayJSON struct {
		Replace map[string]string `json:"replace,omitempty"`
	}
	b, err := json.Marshal(OverlayJSON{Replace: overlays})
	if err != nil {
		return "", nil, err
	}
	filename = filepath.Join(dir, "overlay.json")
	if err := os.WriteFile(filename, b, 0666); err != nil {
		return "", nil, err
	}

	return filename, nil, nil
}


================================================
FILE: internal/gocommand/invoke_notunix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !unix

package gocommand

import "os"

// sigStuckProcess is the signal to send to kill a hanging subprocess.
// On Unix we send SIGQUIT, but on non-Unix we only have os.Kill.
var sigStuckProcess = os.Kill


================================================
FILE: internal/gocommand/invoke_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocommand_test

import (
	"context"
	"fmt"
	"io/fs"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/testenv"
)

func TestGoVersion(t *testing.T) {
	testenv.NeedsTool(t, "go")

	inv := gocommand.Invocation{
		Verb: "version",
	}
	gocmdRunner := &gocommand.Runner{}
	if _, err := gocmdRunner.Run(context.Background(), inv); err != nil {
		t.Error(err)
	}
}

// This is not a test of go/packages at all: it's a test of whether it
// is possible to delete the directory used by go list once it has
// finished. It is intended to evaluate the hypothesis (to explain
// issue #71544) that the go command, on Windows, occasionally fails
// to release all its handles to the temporary directory even when it
// should have finished.
//
// If this test ever fails, the combination of the gocommand package
// and the go command itself has a bug; this has been observed (#73503).
func TestRmdirAfterGoList_Runner(t *testing.T) {
	t.Skip("flaky; see https://github.com/golang/go/issues/73736#issuecomment-2885407104")

	testRmdirAfterGoList(t, func(ctx context.Context, dir string) {
		var runner gocommand.Runner
		stdout, stderr, friendlyErr, err := runner.RunRaw(ctx, gocommand.Invocation{
			Verb:       "list",
			Args:       []string{"-json", "example.com/p"},
			WorkingDir: dir,
		})
		if ctx.Err() != nil {
			return // don't report error if canceled
		}
		if err != nil || friendlyErr != nil {
			t.Fatalf("go list failed: %v, %v (stdout=%s stderr=%s)",
				err, friendlyErr, stdout, stderr)
		}
	})
}

// TestRmdirAfterGoList_Direct is a variant of
// TestRmdirAfterGoList_Runner that executes go list directly, to
// control for the substantial logic of the gocommand package.
//
// It has two variants: the first does not set WaitDelay; the second
// sets it to 30s. If the first variant ever fails, the go command
// itself has a bug; as of May 2025 this has never been observed.
//
// If the second variant fails, it indicates that the WaitDelay
// mechanism is responsible for causing Wait to return before the
// child process has naturally finished. This is to confirm the
// hypothesis at https://github.com/golang/go/issues/73736#issuecomment-2885407104.
func TestRmdirAfterGoList_Direct(t *testing.T) {
	for _, delay := range []time.Duration{0, 30 * time.Second} {
		t.Run(delay.String(), func(t *testing.T) {
			testRmdirAfterGoList(t, func(ctx context.Context, dir string) {
				cmd := exec.Command("go", "list", "-json", "example.com/p")
				cmd.Dir = dir
				cmd.Stdout = new(strings.Builder)
				cmd.Stderr = new(strings.Builder)
				cmd.WaitDelay = delay
				err := cmd.Run()
				if ctx.Err() != nil {
					return // don't report error if canceled
				}
				if err != nil {
					t.Fatalf("go list failed: %v (stdout=%s stderr=%s)",
						err, cmd.Stdout, cmd.Stderr)
				}
			})
		})
	}
}

func testRmdirAfterGoList(t *testing.T, f func(ctx context.Context, dir string)) {
	testenv.NeedsExec(t)

	dir := t.TempDir()
	if err := os.Mkdir(filepath.Join(dir, "p"), 0777); err != nil {
		t.Fatalf("mkdir p: %v", err)
	}

	// Create a go.mod file and 100 trivial Go files for the go command to read.
	if err := os.WriteFile(filepath.Join(dir, "go.mod"), []byte("module example.com"), 0666); err != nil {
		t.Fatal(err)
	}
	for i := range 100 {
		filename := filepath.Join(dir, fmt.Sprintf("p/%d.go", i))
		if err := os.WriteFile(filename, []byte("package p"), 0666); err != nil {
			t.Fatal(err)
		}
	}

	t0 := time.Now()
	g, ctx := errgroup.WithContext(context.Background())
	for range 10 {
		g.Go(func() error {
			f(ctx, dir)
			// Return an error so that concurrent invocations are canceled.
			return fmt.Errorf("oops")
		})
	}
	g.Wait() // ignore error (expected)

	t.Logf("10 concurrent executions (9 canceled) took %v", time.Since(t0))

	// This is the critical operation.
	if err := os.RemoveAll(dir); err != nil {
		t.Errorf("failed to remove temp dir: %v", err)
		// List the contents of the directory, for clues.
		filepath.WalkDir(dir, func(path string, d fs.DirEntry, err error) error {
			t.Log(path, d, err)
			return nil
		}) // ignore error
	}
}


================================================
FILE: internal/gocommand/invoke_unix.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build unix

package gocommand

import "syscall"

// Sigstuckprocess is the signal to send to kill a hanging subprocess.
// Send SIGQUIT to get a stack trace.
var sigStuckProcess = syscall.SIGQUIT


================================================
FILE: internal/gocommand/vendor.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocommand

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"time"

	"golang.org/x/mod/semver"
)

// ModuleJSON holds information about a module.
type ModuleJSON struct {
	Path      string      // module path
	Version   string      // module version
	Versions  []string    // available module versions (with -versions)
	Replace   *ModuleJSON // replaced by this module
	Time      *time.Time  // time version was created
	Update    *ModuleJSON // available update, if any (with -u)
	Main      bool        // is this the main module?
	Indirect  bool        // is this module only an indirect dependency of main module?
	Dir       string      // directory holding files for this module, if any
	GoMod     string      // path to go.mod file used when loading this module, if any
	GoVersion string      // go version used in module
}

var modFlagRegexp = regexp.MustCompile(`-mod[ =](\w+)`)

// VendorEnabled reports whether vendoring is enabled. It takes a *Runner to execute Go commands
// with the supplied context.Context and Invocation. The Invocation can contain pre-defined fields,
// of which only Verb and Args are modified to run the appropriate Go command.
// Inspired by setDefaultBuildMod in modload/init.go
func VendorEnabled(ctx context.Context, inv Invocation, r *Runner) (bool, *ModuleJSON, error) {
	mainMod, go114, err := getMainModuleAnd114(ctx, inv, r)
	if err != nil {
		return false, nil, err
	}

	// We check the GOFLAGS to see if there is anything overridden or not.
	inv.Verb = "env"
	inv.Args = []string{"GOFLAGS"}
	stdout, err := r.Run(ctx, inv)
	if err != nil {
		return false, nil, err
	}
	goflags := string(bytes.TrimSpace(stdout.Bytes()))
	matches := modFlagRegexp.FindStringSubmatch(goflags)
	var modFlag string
	if len(matches) != 0 {
		modFlag = matches[1]
	}
	// Don't override an explicit '-mod=' argument.
	if modFlag == "vendor" {
		return true, mainMod, nil
	} else if modFlag != "" {
		return false, nil, nil
	}
	if mainMod == nil || !go114 {
		return false, nil, nil
	}
	// Check 1.14's automatic vendor mode.
	if fi, err := os.Stat(filepath.Join(mainMod.Dir, "vendor")); err == nil && fi.IsDir() {
		if mainMod.GoVersion != "" && semver.Compare("v"+mainMod.GoVersion, "v1.14") >= 0 {
			// The Go version is at least 1.14, and a vendor directory exists.
			// Set -mod=vendor by default.
			return true, mainMod, nil
		}
	}
	return false, nil, nil
}

// getMainModuleAnd114 gets one of the main modules' information and whether the
// go command in use is 1.14+. This is the information needed to figure out
// if vendoring should be enabled.
func getMainModuleAnd114(ctx context.Context, inv Invocation, r *Runner) (*ModuleJSON, bool, error) {
	const format = `{{.Path}}
{{.Dir}}
{{.GoMod}}
{{.GoVersion}}
{{range context.ReleaseTags}}{{if eq . "go1.14"}}{{.}}{{end}}{{end}}
`
	inv.Verb = "list"
	inv.Args = []string{"-m", "-f", format}
	stdout, err := r.Run(ctx, inv)
	if err != nil {
		return nil, false, err
	}

	lines := strings.Split(stdout.String(), "\n")
	if len(lines) < 5 {
		return nil, false, fmt.Errorf("unexpected stdout: %q", stdout.String())
	}
	mod := &ModuleJSON{
		Path:      lines[0],
		Dir:       lines[1],
		GoMod:     lines[2],
		GoVersion: lines[3],
		Main:      true,
	}
	return mod, lines[4] == "go1.14", nil
}

// WorkspaceVendorEnabled reports whether workspace vendoring is enabled. It takes a *Runner to execute Go commands
// with the supplied context.Context and Invocation. The Invocation can contain pre-defined fields,
// of which only Verb and Args are modified to run the appropriate Go command.
// Inspired by setDefaultBuildMod in modload/init.go
func WorkspaceVendorEnabled(ctx context.Context, inv Invocation, r *Runner) (bool, []*ModuleJSON, error) {
	inv.Verb = "env"
	inv.Args = []string{"GOWORK"}
	stdout, err := r.Run(ctx, inv)
	if err != nil {
		return false, nil, err
	}
	goWork := string(bytes.TrimSpace(stdout.Bytes()))
	if fi, err := os.Stat(filepath.Join(filepath.Dir(goWork), "vendor")); err == nil && fi.IsDir() {
		mainMods, err := getWorkspaceMainModules(ctx, inv, r)
		if err != nil {
			return false, nil, err
		}
		return true, mainMods, nil
	}
	return false, nil, nil
}

// getWorkspaceMainModules gets the main modules' information.
// This is the information needed to figure out if vendoring should be enabled.
func getWorkspaceMainModules(ctx context.Context, inv Invocation, r *Runner) ([]*ModuleJSON, error) {
	const format = `{{.Path}}
{{.Dir}}
{{.GoMod}}
{{.GoVersion}}
`
	inv.Verb = "list"
	inv.Args = []string{"-m", "-f", format}
	stdout, err := r.Run(ctx, inv)
	if err != nil {
		return nil, err
	}

	lines := strings.Split(strings.TrimSuffix(stdout.String(), "\n"), "\n")
	if len(lines) < 4 {
		return nil, fmt.Errorf("unexpected stdout: %q", stdout.String())
	}
	mods := make([]*ModuleJSON, 0, len(lines)/4)
	for i := 0; i < len(lines); i += 4 {
		mods = append(mods, &ModuleJSON{
			Path:      lines[i],
			Dir:       lines[i+1],
			GoMod:     lines[i+2],
			GoVersion: lines[i+3],
			Main:      true,
		})
	}
	return mods, nil
}


================================================
FILE: internal/gocommand/version.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocommand

import (
	"context"
	"fmt"
	"regexp"
	"strings"
)

// GoVersion reports the minor version number of the highest release
// tag built into the go command on the PATH.
//
// Note that this may be higher than the version of the go tool used
// to build this application, and thus the versions of the standard
// go/{scanner,parser,ast,types} packages that are linked into it.
// In that case, callers should either downgrade to the version of
// go used to build the application, or report an error that the
// application is too old to use the go command on the PATH.
func GoVersion(ctx context.Context, inv Invocation, r *Runner) (int, error) {
	inv.Verb = "list"
	inv.Args = []string{"-e", "-f", `{{context.ReleaseTags}}`, `--`, `unsafe`}
	inv.BuildFlags = nil // This is not a build command.
	inv.ModFlag = ""
	inv.ModFile = ""
	// Set GO111MODULE=off so that we are immune to errors in go.{work,mod}.
	// Unfortunately, this breaks the Go 1.21+ toolchain directive and
	// may affect the set of ReleaseTags; see #68495.
	inv.Env = append(inv.Env[:len(inv.Env):len(inv.Env)], "GO111MODULE=off")

	stdoutBytes, err := r.Run(ctx, inv)
	if err != nil {
		return 0, err
	}
	stdout := stdoutBytes.String()
	if len(stdout) < 3 {
		return 0, fmt.Errorf("bad ReleaseTags output: %q", stdout)
	}
	// Split up "[go1.1 go1.15]" and return highest go1.X value.
	tags := strings.Fields(stdout[1 : len(stdout)-2])
	for i := len(tags) - 1; i >= 0; i-- {
		var version int
		if _, err := fmt.Sscanf(tags[i], "go1.%d", &version); err != nil {
			continue
		}
		return version, nil
	}
	return 0, fmt.Errorf("no parseable ReleaseTags in %v", tags)
}

// GoVersionOutput returns the complete output of the go version command.
func GoVersionOutput(ctx context.Context, inv Invocation, r *Runner) (string, error) {
	inv.Verb = "version"
	goVersion, err := r.Run(ctx, inv)
	if err != nil {
		return "", err
	}
	return goVersion.String(), nil
}

// ParseGoVersionOutput extracts the Go version string
// from the output of the "go version" command.
// Given an unrecognized form, it returns an empty string.
func ParseGoVersionOutput(data string) string {
	re := regexp.MustCompile(`^go version (go\S+|devel \S+)`)
	m := re.FindStringSubmatch(data)
	if len(m) != 2 {
		return "" // unrecognized version
	}
	return m[1]
}


================================================
FILE: internal/gocommand/version_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gocommand

import (
	"strconv"
	"testing"
)

func TestParseGoVersionOutput(t *testing.T) {
	tests := []struct {
		args string
		want string
	}{
		{"go version go1.12 linux/amd64", "go1.12"},
		{"go version go1.18.1 darwin/amd64", "go1.18.1"},
		{"go version go1.19.rc1 windows/arm64", "go1.19.rc1"},
		{"go version devel d5de62df152baf4de6e9fe81933319b86fd95ae4 linux/386", "devel d5de62df152baf4de6e9fe81933319b86fd95ae4"},
		{"go version devel go1.20-1f068f0dc7 Tue Oct 18 20:58:37 2022 +0000 darwin/amd64", "devel go1.20-1f068f0dc7"},
		{"v1.19.1 foo/bar", ""},
	}
	for i, tt := range tests {
		t.Run(strconv.Itoa(i), func(t *testing.T) {
			if got := ParseGoVersionOutput(tt.args); got != tt.want {
				t.Errorf("parseGoVersionOutput() = %v, want %v", got, tt.want)
			}
		})
	}
}


================================================
FILE: internal/gopathwalk/walk.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package gopathwalk is like filepath.Walk but specialized for finding Go
// packages, particularly in $GOPATH and $GOROOT.
package gopathwalk

import (
	"bufio"
	"bytes"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"sync"
	"time"
)

// Options controls the behavior of a Walk call.
type Options struct {
	// If Logf is non-nil, debug logging is enabled through this function.
	Logf func(format string, args ...any)

	// Search module caches. Also disables legacy goimports ignore rules.
	ModulesEnabled bool

	// Maximum number of concurrent calls to user-provided callbacks,
	// or 0 for GOMAXPROCS.
	Concurrency int
}

// RootType indicates the type of a Root.
type RootType int

const (
	RootUnknown RootType = iota
	RootGOROOT
	RootGOPATH
	RootCurrentModule
	RootModuleCache
	RootOther
)

// A Root is a starting point for a Walk.
type Root struct {
	Path string
	Type RootType
}

// Walk concurrently walks Go source directories ($GOROOT, $GOPATH, etc) to find packages.
//
// For each package found, add will be called with the absolute
// paths of the containing source directory and the package directory.
//
// Unlike filepath.WalkDir, Walk follows symbolic links
// (while guarding against cycles).
func Walk(roots []Root, add func(root Root, dir string), opts Options) {
	WalkSkip(roots, add, func(Root, string) bool { return false }, opts)
}

// WalkSkip concurrently walks Go source directories ($GOROOT, $GOPATH, etc) to
// find packages.
//
// For each package found, add will be called with the absolute
// paths of the containing source directory and the package directory.
// For each directory that will be scanned, skip will be called
// with the absolute paths of the containing source directory and the directory.
// If skip returns false on a directory it will be processed.
//
// Unlike filepath.WalkDir, WalkSkip follows symbolic links
// (while guarding against cycles).
func WalkSkip(roots []Root, add func(root Root, dir string), skip func(root Root, dir string) bool, opts Options) {
	for _, root := range roots {
		walkDir(root, add, skip, opts)
	}
}

// walkDir creates a walker and starts fastwalk with this walker.
func walkDir(root Root, add func(Root, string), skip func(root Root, dir string) bool, opts Options) {
	if opts.Logf == nil {
		opts.Logf = func(format string, args ...any) {}
	}
	if _, err := os.Stat(root.Path); os.IsNotExist(err) {
		opts.Logf("skipping nonexistent directory: %v", root.Path)
		return
	}
	start := time.Now()
	opts.Logf("scanning %s", root.Path)

	concurrency := opts.Concurrency
	if concurrency == 0 {
		// The walk be either CPU-bound or I/O-bound, depending on what the
		// caller-supplied add function does and the details of the user's platform
		// and machine. Rather than trying to fine-tune the concurrency level for a
		// specific environment, we default to GOMAXPROCS: it is likely to be a good
		// choice for a CPU-bound add function, and if it is instead I/O-bound, then
		// dealing with I/O saturation is arguably the job of the kernel and/or
		// runtime. (Oversaturating I/O seems unlikely to harm performance as badly
		// as failing to saturate would.)
		concurrency = runtime.GOMAXPROCS(0)
	}
	w := &walker{
		root: root,
		add:  add,
		skip: skip,
		opts: opts,
		sem:  make(chan struct{}, concurrency),
	}
	w.init()

	w.sem <- struct{}{}
	path := root.Path
	if path == "" {
		path = "."
	}
	if fi, err := os.Lstat(path); err == nil {
		w.walk(path, nil, fs.FileInfoToDirEntry(fi))
	} else {
		w.opts.Logf("scanning directory %v: %v", root.Path, err)
	}
	<-w.sem
	w.walking.Wait()

	opts.Logf("scanned %s in %v", root.Path, time.Since(start))
}

// walker is the callback for fastwalk.Walk.
type walker struct {
	root Root                    // The source directory to scan.
	add  func(Root, string)      // The callback that will be invoked for every possible Go package dir.
	skip func(Root, string) bool // The callback that will be invoked for every dir. dir is skipped if it returns true.
	opts Options                 // Options passed to Walk by the user.

	walking     sync.WaitGroup
	sem         chan struct{} // Channel of semaphore tokens; send to acquire, receive to release.
	ignoredDirs []string

	added sync.Map // map[string]bool
}

// A symlinkList is a linked list of os.FileInfos for parent directories
// reached via symlinks.
type symlinkList struct {
	info os.FileInfo
	prev *symlinkList
}

// init initializes the walker based on its Options
func (w *walker) init() {
	var ignoredPaths []string
	if w.root.Type == RootModuleCache {
		ignoredPaths = []string{"cache"}
	}
	if !w.opts.ModulesEnabled && w.root.Type == RootGOPATH {
		ignoredPaths = w.getIgnoredDirs(w.root.Path)
		ignoredPaths = append(ignoredPaths, "v", "mod")
	}

	for _, p := range ignoredPaths {
		full := filepath.Join(w.root.Path, p)
		w.ignoredDirs = append(w.ignoredDirs, full)
		w.opts.Logf("Directory added to ignore list: %s", full)
	}
}

// getIgnoredDirs reads an optional config file at <path>/.goimportsignore
// of relative directories to ignore when scanning for go files.
// The provided path is one of the $GOPATH entries with "src" appended.
func (w *walker) getIgnoredDirs(path string) []string {
	file := filepath.Join(path, ".goimportsignore")
	slurp, err := os.ReadFile(file)
	if err != nil {
		w.opts.Logf("%v", err)
	} else {
		w.opts.Logf("Read %s", file)
	}
	if err != nil {
		return nil
	}

	var ignoredDirs []string
	bs := bufio.NewScanner(bytes.NewReader(slurp))
	for bs.Scan() {
		line := strings.TrimSpace(bs.Text())
		if line == "" || strings.HasPrefix(line, "#") {
			continue
		}
		ignoredDirs = append(ignoredDirs, line)
	}
	return ignoredDirs
}

// shouldSkipDir reports whether the file should be skipped or not.
func (w *walker) shouldSkipDir(dir string) bool {
	if slices.Contains(w.ignoredDirs, dir) {
		return true
	}
	if w.skip != nil {
		// Check with the user specified callback.
		return w.skip(w.root, dir)
	}
	return false
}

// walk walks through the given path.
//
// Errors are logged if w.opts.Logf is non-nil, but otherwise ignored.
func (w *walker) walk(path string, pathSymlinks *symlinkList, d fs.DirEntry) {
	if d.Type()&os.ModeSymlink != 0 {
		// Walk the symlink's target rather than the symlink itself.
		//
		// (Note that os.Stat, unlike the lower-lever os.Readlink,
		// follows arbitrarily many layers of symlinks, so it will eventually
		// reach either a non-symlink or a nonexistent target.)
		//
		// TODO(bcmills): 'go list all' itself ignores symlinks within GOROOT/src
		// and GOPATH/src. Do we really need to traverse them here? If so, why?

		fi, err := os.Stat(path)
		if err != nil {
			w.opts.Logf("%v", err)
			return
		}

		// Avoid walking symlink cycles: if we have already followed a symlink to
		// this directory as a parent of itself, don't follow it again.
		//
		// This doesn't catch the first time through a cycle, but it also minimizes
		// the number of extra stat calls we make if we *don't* encounter a cycle.
		// Since we don't actually expect to encounter symlink cycles in practice,
		// this seems like the right tradeoff.
		for parent := pathSymlinks; parent != nil; parent = parent.prev {
			if os.SameFile(fi, parent.info) {
				return
			}
		}

		pathSymlinks = &symlinkList{
			info: fi,
			prev: pathSymlinks,
		}
		d = fs.FileInfoToDirEntry(fi)
	}

	if d.Type().IsRegular() {
		if !strings.HasSuffix(path, ".go") {
			return
		}

		dir := filepath.Dir(path)
		if dir == w.root.Path && (w.root.Type == RootGOROOT || w.root.Type == RootGOPATH) {
			// Doesn't make sense to have regular files
			// directly in your $GOPATH/src or $GOROOT/src.
			//
			// TODO(bcmills): there are many levels of directory within
			// RootModuleCache where this also wouldn't make sense,
			// Can we generalize this to any directory without a corresponding
			// import path?
			return
		}

		if _, dup := w.added.LoadOrStore(dir, true); !dup {
			w.add(w.root, dir)
		}
	}

	if !d.IsDir() {
		return
	}

	base := filepath.Base(path)
	if base == "" || base[0] == '.' || base[0] == '_' ||
		base == "testdata" ||
		(w.root.Type == RootGOROOT && w.opts.ModulesEnabled && base == "vendor") ||
		(!w.opts.ModulesEnabled && base == "node_modules") ||
		w.shouldSkipDir(path) {
		return
	}

	// Read the directory and walk its entries.

	f, err := os.Open(path)
	if err != nil {
		w.opts.Logf("%v", err)
		return
	}
	defer f.Close()

	for {
		// We impose an arbitrary limit on the number of ReadDir results per
		// directory to limit the amount of memory consumed for stale or upcoming
		// directory entries. The limit trades off CPU (number of syscalls to read
		// the whole directory) against RAM (reachable directory entries other than
		// the one currently being processed).
		//
		// Since we process the directories recursively, we will end up maintaining
		// a slice of entries for each level of the directory tree.
		// (Compare https://go.dev/issue/36197.)
		ents, err := f.ReadDir(1024)
		if err != nil {
			if err != io.EOF {
				w.opts.Logf("%v", err)
			}
			break
		}

		for _, d := range ents {
			nextPath := filepath.Join(path, d.Name())
			if d.IsDir() {
				select {
				case w.sem <- struct{}{}:
					// Got a new semaphore token, so we can traverse the directory concurrently.
					d := d
					w.walking.Add(1)
					go func() {
						defer func() {
							<-w.sem
							w.walking.Done()
						}()
						w.walk(nextPath, pathSymlinks, d)
					}()
					continue

				default:
					// No tokens available, so traverse serially.
				}
			}

			w.walk(nextPath, pathSymlinks, d)
		}
	}
}


================================================
FILE: internal/gopathwalk/walk_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package gopathwalk

import (
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"sort"
	"strings"
	"sync"
	"testing"
)

func TestSymlinkTraversal(t *testing.T) {
	t.Parallel()

	gopath := t.TempDir()

	if err := mapToDir(gopath, map[string]string{
		"a/b/c":          "LINK:../../a/d",
		"a/b/pkg/pkg.go": "package pkg",
		"a/d/e":          "LINK:../../a/b",
		"a/d/pkg/pkg.go": "package pkg",
		"a/f/loop":       "LINK:../f",
		"a/f/pkg/pkg.go": "package pkg",
		"a/g/pkg/pkg.go": "LINK:../../f/pkg/pkg.go",
		"a/self":         "LINK:.",
	}); err != nil {
		switch runtime.GOOS {
		case "windows", "plan9":
			t.Skipf("skipping symlink-requiring test on %s", runtime.GOOS)
		}
		t.Fatal(err)
	}

	pkgc := make(chan []string, 1)
	pkgc <- nil
	add := func(root Root, dir string) {
		rel, err := filepath.Rel(filepath.Join(root.Path, "src"), dir)
		if err != nil {
			t.Error(err)
		}
		pkgc <- append(<-pkgc, filepath.ToSlash(rel))
	}

	Walk([]Root{{Path: gopath, Type: RootGOPATH}}, add, Options{Logf: t.Logf})

	pkgs := <-pkgc
	sort.Strings(pkgs)
	t.Logf("Found packages:\n\t%s", strings.Join(pkgs, "\n\t"))

	got := make(map[string]bool, len(pkgs))
	for _, pkg := range pkgs {
		got[pkg] = true
	}
	tests := []struct {
		path string
		want bool
		why  string
	}{
		{
			path: "a/b/pkg",
			want: true,
			why:  "found via regular directories",
		},
		{
			path: "a/b/c/pkg",
			want: true,
			why:  "found via non-cyclic dir link",
		},
		{
			path: "a/b/c/e/pkg",
			want: true,
			why:  "found via two non-cyclic dir links",
		},
		{
			path: "a/d/e/c/pkg",
			want: true,
			why:  "found via two non-cyclic dir links",
		},
		{
			path: "a/f/loop/pkg",
			want: true,
			why:  "found via a single parent-dir link",
		},
		{
			path: "a/f/loop/loop/pkg",
			want: false,
			why:  "would follow loop symlink twice",
		},
		{
			path: "a/self/b/pkg",
			want: true,
			why:  "follows self-link once",
		},
		{
			path: "a/self/self/b/pkg",
			want: false,
			why:  "would follow self-link twice",
		},
	}
	for _, tc := range tests {
		if got[tc.path] != tc.want {
			if tc.want {
				t.Errorf("MISSING: %s (%s)", tc.path, tc.why)
			} else {
				t.Errorf("UNEXPECTED: %s (%s)", tc.path, tc.why)
			}
		}
	}
}

// TestSkip tests that various goimports rules are followed in non-modules mode.
func TestSkip(t *testing.T) {
	t.Parallel()

	dir := t.TempDir()

	if err := mapToDir(dir, map[string]string{
		"ignoreme/f.go":     "package ignoreme",     // ignored by .goimportsignore
		"node_modules/f.go": "package nodemodules;", // ignored by hardcoded node_modules filter
		"v/f.go":            "package v;",           // ignored by hardcoded vgo cache rule
		"mod/f.go":          "package mod;",         // ignored by hardcoded vgo cache rule
		"shouldfind/f.go":   "package shouldfind;",  // not ignored

		".goimportsignore": "ignoreme\n",
	}); err != nil {
		t.Fatal(err)
	}

	var found []string
	var mu sync.Mutex
	walkDir(Root{filepath.Join(dir, "src"), RootGOPATH},
		func(root Root, dir string) {
			mu.Lock()
			defer mu.Unlock()
			found = append(found, dir[len(root.Path)+1:])
		}, func(root Root, dir string) bool {
			return false
		}, Options{
			ModulesEnabled: false,
			Logf:           t.Logf,
		})
	if want := []string{"shouldfind"}; !reflect.DeepEqual(found, want) {
		t.Errorf("expected to find only %v, got %v", want, found)
	}
}

// TestSkipFunction tests that scan successfully skips directories from user callback.
func TestSkipFunction(t *testing.T) {
	t.Parallel()

	dir := t.TempDir()

	if err := mapToDir(dir, map[string]string{
		"ignoreme/f.go":           "package ignoreme",    // ignored by skip
		"ignoreme/subignore/f.go": "package subignore",   // also ignored by skip
		"shouldfind/f.go":         "package shouldfind;", // not ignored
	}); err != nil {
		t.Fatal(err)
	}

	var found []string
	var mu sync.Mutex
	walkDir(Root{filepath.Join(dir, "src"), RootGOPATH},
		func(root Root, dir string) {
			mu.Lock()
			defer mu.Unlock()
			found = append(found, dir[len(root.Path)+1:])
		}, func(root Root, dir string) bool {
			return strings.HasSuffix(dir, "ignoreme")
		},
		Options{
			ModulesEnabled: false,
			Logf:           t.Logf,
		})
	if want := []string{"shouldfind"}; !reflect.DeepEqual(found, want) {
		t.Errorf("expected to find only %v, got %v", want, found)
	}
}

// TestWalkSymlinkConcurrentDeletion is a regression test for the panic reported
// in https://go.dev/issue/58054#issuecomment-1791513726.
func TestWalkSymlinkConcurrentDeletion(t *testing.T) {
	t.Parallel()

	src := t.TempDir()

	m := map[string]string{
		"dir/readme.txt": "dir is not a go package",
		"dirlink":        "LINK:dir",
	}
	if err := mapToDir(src, m); err != nil {
		switch runtime.GOOS {
		case "windows", "plan9":
			t.Skipf("skipping symlink-requiring test on %s", runtime.GOOS)
		}
		t.Fatal(err)
	}

	done := make(chan struct{})
	go func() {
		if err := os.RemoveAll(src); err != nil {
			t.Log(err)
		}
		close(done)
	}()
	defer func() {
		<-done
	}()

	add := func(root Root, dir string) {
		t.Errorf("unexpected call to add(%q, %q)", root.Path, dir)
	}
	Walk([]Root{{Path: src, Type: RootGOPATH}}, add, Options{Logf: t.Logf})
}

func mapToDir(destDir string, files map[string]string) error {
	var symlinkPaths []string
	for path, contents := range files {
		file := filepath.Join(destDir, "src", path)
		if err := os.MkdirAll(filepath.Dir(file), 0755); err != nil {
			return err
		}
		var err error
		if strings.HasPrefix(contents, "LINK:") {
			// To work around https://go.dev/issue/39183, wait to create symlinks
			// until we have created all non-symlink paths.
			symlinkPaths = append(symlinkPaths, path)
		} else {
			err = os.WriteFile(file, []byte(contents), 0644)
		}
		if err != nil {
			return err
		}
	}

	for _, path := range symlinkPaths {
		file := filepath.Join(destDir, "src", path)
		target := filepath.FromSlash(strings.TrimPrefix(files[path], "LINK:"))
		err := os.Symlink(target, file)
		if err != nil {
			return err
		}
	}

	return nil
}


================================================
FILE: internal/goplsexport/export.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package goplsexport provides various backdoors to not-yet-published
// parts of x/tools that are needed by gopls.
package goplsexport

import "golang.org/x/tools/go/analysis"

var (
	ErrorsAsTypeModernizer *analysis.Analyzer // = modernize.errorsastypeAnalyzer
	StdIteratorsModernizer *analysis.Analyzer // = modernize.stditeratorsAnalyzer
	PlusBuildModernizer    *analysis.Analyzer // = modernize.plusbuildAnalyzer
	StringsCutModernizer   *analysis.Analyzer // = modernize.stringscutAnalyzer
	UnsafeFuncsModernizer  *analysis.Analyzer // = modernize.unsafeFuncsAnalyzer
	AtomicTypesModernizer  *analysis.Analyzer // = modernize.atomicTypesAnalyzer
)


================================================
FILE: internal/goroot/importcfg.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package goroot is a copy of package internal/goroot
// in the main GO repot. It provides a utility to produce
// an import path to package file map mapping
// standard library packages to the locations of their export
// data files.
package goroot

import (
	"fmt"
	"os/exec"
	"strings"
	"sync"
)

// PkgfileMap returns a map of package paths to the location on disk
// of the .a file for the package.
// The caller must not modify the map.
func PkgfileMap() (map[string]string, error) {
	return pkgFileMapOnce()
}

var pkgFileMapOnce = sync.OnceValues(func() (map[string]string, error) {
	m := make(map[string]string)
	output, err := exec.Command("go", "list", "-export", "-e", "-f", "{{.ImportPath}} {{.Export}}", "std", "cmd").Output()
	if err != nil {
		return m, err
	}
	for line := range strings.SplitSeq(string(output), "\n") {
		if line == "" {
			continue
		}
		sp := strings.SplitN(line, " ", 2)
		if len(sp) != 2 {
			return m, fmt.Errorf("determining pkgfile map: invalid line in go list output: %q", line)
		}
		importPath, export := sp[0], sp[1]
		if export != "" {
			m[importPath] = export
		}
	}
	return m, nil
})


================================================
FILE: internal/imports/fix.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"go/types"
	"io/fs"
	"io/ioutil"
	"maps"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"sort"
	"strconv"
	"strings"
	"sync"
	"unicode"
	"unicode/utf8"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/gopathwalk"
	"golang.org/x/tools/internal/stdlib"
)

// importToGroup is a list of functions which map from an import path to
// a group number.
var importToGroup = []func(localPrefix, importPath string) (num int, ok bool){
	func(localPrefix, importPath string) (num int, ok bool) {
		if localPrefix == "" {
			return
		}
		for p := range strings.SplitSeq(localPrefix, ",") {
			if strings.HasPrefix(importPath, p) || strings.TrimSuffix(p, "/") == importPath {
				return 3, true
			}
		}
		return
	},
	func(_, importPath string) (num int, ok bool) {
		if strings.HasPrefix(importPath, "appengine") {
			return 2, true
		}
		return
	},
	func(_, importPath string) (num int, ok bool) {
		firstComponent := strings.Split(importPath, "/")[0]
		if strings.Contains(firstComponent, ".") {
			return 1, true
		}
		return
	},
}

func importGroup(localPrefix, importPath string) int {
	for _, fn := range importToGroup {
		if n, ok := fn(localPrefix, importPath); ok {
			return n
		}
	}
	return 0
}

type ImportFixType int

const (
	AddImport ImportFixType = iota
	DeleteImport
	SetImportName
)

type ImportFix struct {
	// StmtInfo represents the import statement this fix will add, remove, or change.
	StmtInfo ImportInfo
	// IdentName is the identifier that this fix will add or remove.
	IdentName string
	// FixType is the type of fix this is (AddImport, DeleteImport, SetImportName).
	FixType   ImportFixType
	Relevance float64 // see pkg
}

// parseOtherFiles parses all the Go files in srcDir except filename, including
// test files if filename looks like a test.
//
// It returns an error only if ctx is cancelled. Files with parse errors are
// ignored.
func parseOtherFiles(ctx context.Context, fset *token.FileSet, srcDir, filename string) ([]*ast.File, error) {
	// This could use go/packages but it doesn't buy much, and it fails
	// with https://golang.org/issue/26296 in LoadFiles mode in some cases.
	considerTests := strings.HasSuffix(filename, "_test.go")

	fileBase := filepath.Base(filename)
	packageFileInfos, err := os.ReadDir(srcDir)
	if err != nil {
		return nil, ctx.Err()
	}

	var files []*ast.File
	for _, fi := range packageFileInfos {
		if ctx.Err() != nil {
			return nil, ctx.Err()
		}
		if fi.Name() == fileBase || !strings.HasSuffix(fi.Name(), ".go") {
			continue
		}
		if !considerTests && strings.HasSuffix(fi.Name(), "_test.go") {
			continue
		}

		f, err := parser.ParseFile(fset, filepath.Join(srcDir, fi.Name()), nil, parser.SkipObjectResolution)
		if err != nil {
			continue
		}

		files = append(files, f)
	}

	return files, ctx.Err()
}

// addGlobals puts the names of package vars into the provided map.
func addGlobals(f *ast.File, globals map[string]bool) {
	for _, decl := range f.Decls {
		genDecl, ok := decl.(*ast.GenDecl)
		if !ok {
			continue
		}

		for _, spec := range genDecl.Specs {
			valueSpec, ok := spec.(*ast.ValueSpec)
			if !ok {
				continue
			}
			globals[valueSpec.Names[0].Name] = true
		}
	}
}

// collectReferences builds a map of selector expressions, from
// left hand side (X) to a set of right hand sides (Sel).
func collectReferences(f *ast.File) References {
	refs := References{}

	var visitor visitFn
	visitor = func(node ast.Node) ast.Visitor {
		if node == nil {
			return visitor
		}
		switch v := node.(type) {
		case *ast.SelectorExpr:
			xident, ok := v.X.(*ast.Ident)
			if !ok {
				break
			}
			if xident.Obj != nil {
				// If the parser can resolve it, it's not a package ref.
				break
			}
			if !ast.IsExported(v.Sel.Name) {
				// Whatever this is, it's not exported from a package.
				break
			}
			pkgName := xident.Name
			r := refs[pkgName]
			if r == nil {
				r = make(map[string]bool)
				refs[pkgName] = r
			}
			r[v.Sel.Name] = true
		}
		return visitor
	}
	ast.Walk(visitor, f)
	return refs
}

// collectImports returns all the imports in f.
// Unnamed imports (., _) and "C" are ignored.
func collectImports(f *ast.File) []*ImportInfo {
	var imports []*ImportInfo
	for _, imp := range f.Imports {
		var name string
		if imp.Name != nil {
			name = imp.Name.Name
		}
		if imp.Path.Value == `"C"` || name == "_" || name == "." {
			continue
		}
		path := strings.Trim(imp.Path.Value, `"`)
		imports = append(imports, &ImportInfo{
			Name:       name,
			ImportPath: path,
		})
	}
	return imports
}

// findMissingImport searches pass's candidates for an import that provides
// pkg, containing all of syms.
func (p *pass) findMissingImport(pkg string, syms map[string]bool) *ImportInfo {
	for _, candidate := range p.candidates {
		pkgInfo, ok := p.knownPackages[candidate.ImportPath]
		if !ok {
			continue
		}
		if p.importIdentifier(candidate) != pkg {
			continue
		}

		allFound := true
		for right := range syms {
			if !pkgInfo.Exports[right] {
				allFound = false
				break
			}
		}

		if allFound {
			return candidate
		}
	}
	return nil
}

// A pass contains all the inputs and state necessary to fix a file's imports.
// It can be modified in some ways during use; see comments below.
type pass struct {
	// Inputs. These must be set before a call to load, and not modified after.
	fset                 *token.FileSet // fset used to parse f and its siblings.
	f                    *ast.File      // the file being fixed.
	srcDir               string         // the directory containing f.
	logf                 func(string, ...any)
	source               Source      // the environment to use for go commands, etc.
	loadRealPackageNames bool        // if true, load package names from disk rather than guessing them.
	otherFiles           []*ast.File // sibling files.
	goroot               string

	// Intermediate state, generated by load.
	existingImports map[string][]*ImportInfo
	allRefs         References
	missingRefs     References

	// Inputs to fix. These can be augmented between successive fix calls.
	lastTry       bool                    // indicates that this is the last call and fix should clean up as best it can.
	candidates    []*ImportInfo           // candidate imports in priority order.
	knownPackages map[string]*PackageInfo // information about all known packages.
}

// loadPackageNames saves the package names for everything referenced by imports.
func (p *pass) loadPackageNames(ctx context.Context, imports []*ImportInfo) error {
	if p.logf != nil {
		p.logf("loading package names for %v packages", len(imports))
		defer func() {
			p.logf("done loading package names for %v packages", len(imports))
		}()
	}
	var unknown []string
	for _, imp := range imports {
		if _, ok := p.knownPackages[imp.ImportPath]; ok {
			continue
		}
		unknown = append(unknown, imp.ImportPath)
	}

	names, err := p.source.LoadPackageNames(ctx, p.srcDir, unknown)
	if err != nil {
		return err
	}

	// TODO(rfindley): revisit this. Why do we need to store known packages with
	// no exports? The inconsistent data is confusing.
	for path, name := range names {
		p.knownPackages[path] = &PackageInfo{
			Name:    name,
			Exports: map[string]bool{},
		}
	}
	return nil
}

// WithoutVersion removes a trailing major version, if there is one.
func WithoutVersion(nm string) string {
	if v := path.Base(nm); len(v) > 0 && v[0] == 'v' {
		if _, err := strconv.Atoi(v[1:]); err == nil {
			// this is, for instance, called with rand/v2 and returns rand
			if len(v) < len(nm) {
				xnm := nm[:len(nm)-len(v)-1]
				return path.Base(xnm)
			}
		}
	}
	return nm
}

// importIdentifier returns the identifier that imp will introduce. It will
// guess if the package name has not been loaded, e.g. because the source
// is not available.
func (p *pass) importIdentifier(imp *ImportInfo) string {
	if imp.Name != "" {
		return imp.Name
	}
	known := p.knownPackages[imp.ImportPath]
	if known != nil && known.Name != "" {
		return WithoutVersion(known.Name)
	}
	return ImportPathToAssumedName(imp.ImportPath)
}

// load reads in everything necessary to run a pass, and reports whether the
// file already has all the imports it needs. It fills in p.missingRefs with the
// file's missing symbols, if any, or removes unused imports if not.
func (p *pass) load(ctx context.Context) ([]*ImportFix, bool) {
	p.knownPackages = map[string]*PackageInfo{}
	p.missingRefs = References{}
	p.existingImports = map[string][]*ImportInfo{}

	// Load basic information about the file in question.
	p.allRefs = collectReferences(p.f)

	// Load stuff from other files in the same package:
	// global variables so we know they don't need resolving, and imports
	// that we might want to mimic.
	globals := map[string]bool{}
	for _, otherFile := range p.otherFiles {
		// Don't load globals from files that are in the same directory
		// but a different package. Using them to suggest imports is OK.
		if p.f.Name.Name == otherFile.Name.Name {
			addGlobals(otherFile, globals)
		}
		p.candidates = append(p.candidates, collectImports(otherFile)...)
	}

	// Resolve all the import paths we've seen to package names, and store
	// f's imports by the identifier they introduce.
	imports := collectImports(p.f)
	if p.loadRealPackageNames {
		err := p.loadPackageNames(ctx, append(imports, p.candidates...))
		if err != nil {
			if p.logf != nil {
				p.logf("loading package names: %v", err)
			}
			return nil, false
		}
	}
	for _, imp := range imports {
		p.existingImports[p.importIdentifier(imp)] = append(p.existingImports[p.importIdentifier(imp)], imp)
	}

	// Find missing references.
	for left, rights := range p.allRefs {
		if globals[left] {
			continue
		}
		_, ok := p.existingImports[left]
		if !ok {
			p.missingRefs[left] = rights
			continue
		}
	}
	if len(p.missingRefs) != 0 {
		return nil, false
	}

	return p.fix()
}

// fix attempts to satisfy missing imports using p.candidates. If it finds
// everything, or if p.lastTry is true, it updates fixes to add the imports it found,
// delete anything unused, and update import names, and returns true.
func (p *pass) fix() ([]*ImportFix, bool) {
	// Find missing imports.
	var selected []*ImportInfo
	for left, rights := range p.missingRefs {
		if imp := p.findMissingImport(left, rights); imp != nil {
			selected = append(selected, imp)
		}
	}

	if !p.lastTry && len(selected) != len(p.missingRefs) {
		return nil, false
	}

	// Found everything, or giving up. Add the new imports and remove any unused.
	var fixes []*ImportFix
	for _, identifierImports := range p.existingImports {
		for _, imp := range identifierImports {
			// We deliberately ignore globals here, because we can't be sure
			// they're in the same package. People do things like put multiple
			// main packages in the same directory, and we don't want to
			// remove imports if they happen to have the same name as a var in
			// a different package.
			if _, ok := p.allRefs[p.importIdentifier(imp)]; !ok {
				fixes = append(fixes, &ImportFix{
					StmtInfo:  *imp,
					IdentName: p.importIdentifier(imp),
					FixType:   DeleteImport,
				})
				continue
			}

			// An existing import may need to update its import name to be correct.
			if name := p.importSpecName(imp); name != imp.Name {
				fixes = append(fixes, &ImportFix{
					StmtInfo: ImportInfo{
						Name:       name,
						ImportPath: imp.ImportPath,
					},
					IdentName: p.importIdentifier(imp),
					FixType:   SetImportName,
				})
			}
		}
	}
	// Collecting fixes involved map iteration, so sort for stability. See
	// golang/go#59976.
	sortFixes(fixes)

	// collect selected fixes in a separate slice, so that it can be sorted
	// separately. Note that these fixes must occur after fixes to existing
	// imports. TODO(rfindley): figure out why.
	var selectedFixes []*ImportFix
	for _, imp := range selected {
		selectedFixes = append(selectedFixes, &ImportFix{
			StmtInfo: ImportInfo{
				Name:       p.importSpecName(imp),
				ImportPath: imp.ImportPath,
			},
			IdentName: p.importIdentifier(imp),
			FixType:   AddImport,
		})
	}
	sortFixes(selectedFixes)

	return append(fixes, selectedFixes...), true
}

func sortFixes(fixes []*ImportFix) {
	sort.Slice(fixes, func(i, j int) bool {
		fi, fj := fixes[i], fixes[j]
		if fi.StmtInfo.ImportPath != fj.StmtInfo.ImportPath {
			return fi.StmtInfo.ImportPath < fj.StmtInfo.ImportPath
		}
		if fi.StmtInfo.Name != fj.StmtInfo.Name {
			return fi.StmtInfo.Name < fj.StmtInfo.Name
		}
		if fi.IdentName != fj.IdentName {
			return fi.IdentName < fj.IdentName
		}
		return fi.FixType < fj.FixType
	})
}

// importSpecName gets the import name of imp in the import spec.
//
// When the import identifier matches the assumed import name, the import name does
// not appear in the import spec.
func (p *pass) importSpecName(imp *ImportInfo) string {
	// If we did not load the real package names, or the name is already set,
	// we just return the existing name.
	if !p.loadRealPackageNames || imp.Name != "" {
		return imp.Name
	}

	ident := p.importIdentifier(imp)
	if ident == ImportPathToAssumedName(imp.ImportPath) {
		return "" // ident not needed since the assumed and real names are the same.
	}
	return ident
}

// apply will perform the fixes on f in order.
func apply(fset *token.FileSet, f *ast.File, fixes []*ImportFix) {
	for _, fix := range fixes {
		switch fix.FixType {
		case DeleteImport:
			astutil.DeleteNamedImport(fset, f, fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
		case AddImport:
			astutil.AddNamedImport(fset, f, fix.StmtInfo.Name, fix.StmtInfo.ImportPath)
		case SetImportName:
			// Find the matching import path and change the name.
			for _, spec := range f.Imports {
				path := strings.Trim(spec.Path.Value, `"`)
				if path == fix.StmtInfo.ImportPath {
					spec.Name = &ast.Ident{
						Name:    fix.StmtInfo.Name,
						NamePos: spec.Pos(),
					}
				}
			}
		}
	}
}

// assumeSiblingImportsValid assumes that siblings' use of packages is valid,
// adding the exports they use.
func (p *pass) assumeSiblingImportsValid() {
	for _, f := range p.otherFiles {
		refs := collectReferences(f)
		imports := collectImports(f)
		importsByName := map[string]*ImportInfo{}
		for _, imp := range imports {
			importsByName[p.importIdentifier(imp)] = imp
		}
		for left, rights := range refs {
			if imp, ok := importsByName[left]; ok {
				if m, ok := stdlib.PackageSymbols[imp.ImportPath]; ok {
					// We have the stdlib in memory; no need to guess.
					rights = symbolNameSet(m)
				}
				// TODO(rfindley): we should set package name here, for consistency.
				p.addCandidate(imp, &PackageInfo{
					// no name; we already know it.
					Exports: rights,
				})
			}
		}
	}
}

// addCandidate adds a candidate import to p, and merges in the information
// in pkg.
func (p *pass) addCandidate(imp *ImportInfo, pkg *PackageInfo) {
	p.candidates = append(p.candidates, imp)
	if existing, ok := p.knownPackages[imp.ImportPath]; ok {
		if existing.Name == "" {
			existing.Name = pkg.Name
		}
		for export := range pkg.Exports {
			existing.Exports[export] = true
		}
	} else {
		p.knownPackages[imp.ImportPath] = pkg
	}
}

// fixImports adds and removes imports from f so that all its references are
// satisfied and there are no unused imports.
//
// This is declared as a variable rather than a function so goimports can
// easily be extended by adding a file with an init function.
//
// DO NOT REMOVE: used internally at Google.
var fixImports = fixImportsDefault

func fixImportsDefault(fset *token.FileSet, f *ast.File, filename string, env *ProcessEnv) error {
	fixes, err := getFixes(context.Background(), fset, f, filename, env)
	if err != nil {
		return err
	}
	apply(fset, f, fixes)
	return nil
}

// getFixes gets the import fixes that need to be made to f in order to fix the imports.
// It does not modify the ast.
func getFixes(ctx context.Context, fset *token.FileSet, f *ast.File, filename string, env *ProcessEnv) ([]*ImportFix, error) {
	source, err := NewProcessEnvSource(env, filename, f.Name.Name)
	if err != nil {
		return nil, err
	}
	goEnv, err := env.goEnv()
	if err != nil {
		return nil, err
	}
	return getFixesWithSource(ctx, fset, f, filename, goEnv["GOROOT"], env.logf, source)
}

func getFixesWithSource(ctx context.Context, fset *token.FileSet, f *ast.File, filename string, goroot string, logf func(string, ...any), source Source) ([]*ImportFix, error) {
	// This logic is defensively duplicated from getFixes.
	abs, err := filepath.Abs(filename)
	if err != nil {
		return nil, err
	}
	srcDir := filepath.Dir(abs)

	if logf != nil {
		logf("fixImports(filename=%q), srcDir=%q ...", filename, srcDir)
	}

	// First pass: looking only at f, and using the naive algorithm to
	// derive package names from import paths, see if the file is already
	// complete. We can't add any imports yet, because we don't know
	// if missing references are actually package vars.
	p := &pass{
		fset:   fset,
		f:      f,
		srcDir: srcDir,
		logf:   logf,
		goroot: goroot,
		source: source,
	}
	if fixes, done := p.load(ctx); done {
		return fixes, nil
	}

	otherFiles, err := parseOtherFiles(ctx, fset, srcDir, filename)
	if err != nil {
		return nil, err
	}

	// Second pass: add information from other files in the same package,
	// like their package vars and imports.
	p.otherFiles = otherFiles
	if fixes, done := p.load(ctx); done {
		return fixes, nil
	}

	// Now we can try adding imports from the stdlib.
	p.assumeSiblingImportsValid()
	addStdlibCandidates(p, p.missingRefs)
	if fixes, done := p.fix(); done {
		return fixes, nil
	}

	// Third pass: get real package names where we had previously used
	// the naive algorithm.
	p = &pass{
		fset:   fset,
		f:      f,
		srcDir: srcDir,
		logf:   logf,
		goroot: goroot,
		source: p.source, // safe to reuse, as it's just a wrapper around env
	}
	p.loadRealPackageNames = true
	p.otherFiles = otherFiles
	if fixes, done := p.load(ctx); done {
		return fixes, nil
	}

	if err := addStdlibCandidates(p, p.missingRefs); err != nil {
		return nil, err
	}
	p.assumeSiblingImportsValid()
	if fixes, done := p.fix(); done {
		return fixes, nil
	}

	// Go look for candidates in $GOPATH, etc. We don't necessarily load
	// the real exports of sibling imports, so keep assuming their contents.
	if err := addExternalCandidates(ctx, p, p.missingRefs, filename); err != nil {
		return nil, err
	}

	p.lastTry = true
	fixes, _ := p.fix()
	return fixes, nil
}

// MaxRelevance is the highest relevance, used for the standard library.
// Chosen arbitrarily to match pre-existing gopls code.
const MaxRelevance = 7.0

// getCandidatePkgs works with the passed callback to find all acceptable packages.
// It deduplicates by import path, and uses a cached stdlib rather than reading
// from disk.
func getCandidatePkgs(ctx context.Context, wrappedCallback *scanCallback, filename, filePkg string, env *ProcessEnv) error {
	notSelf := func(p *pkg) bool {
		return p.packageName != filePkg || p.dir != filepath.Dir(filename)
	}
	goenv, err := env.goEnv()
	if err != nil {
		return err
	}

	var mu sync.Mutex // to guard asynchronous access to dupCheck
	dupCheck := map[string]struct{}{}

	// Start off with the standard library.
	for importPath, symbols := range stdlib.PackageSymbols {
		p := &pkg{
			dir:             filepath.Join(goenv["GOROOT"], "src", importPath),
			importPathShort: importPath,
			packageName:     path.Base(importPath),
			relevance:       MaxRelevance,
		}
		dupCheck[importPath] = struct{}{}
		if notSelf(p) && wrappedCallback.dirFound(p) && wrappedCallback.packageNameLoaded(p) {
			var exports []stdlib.Symbol
			for _, sym := range symbols {
				switch sym.Kind {
				case stdlib.Func, stdlib.Type, stdlib.Var, stdlib.Const:
					exports = append(exports, sym)
				}
			}
			wrappedCallback.exportsLoaded(p, exports)
		}
	}

	scanFilter := &scanCallback{
		rootFound: func(root gopathwalk.Root) bool {
			// Exclude goroot results -- getting them is relatively expensive, not cached,
			// and generally redundant with the in-memory version.
			return root.Type != gopathwalk.RootGOROOT && wrappedCallback.rootFound(root)
		},
		dirFound: wrappedCallback.dirFound,
		packageNameLoaded: func(pkg *pkg) bool {
			mu.Lock()
			defer mu.Unlock()
			if _, ok := dupCheck[pkg.importPathShort]; ok {
				return false
			}
			dupCheck[pkg.importPathShort] = struct{}{}
			return notSelf(pkg) && wrappedCallback.packageNameLoaded(pkg)
		},
		exportsLoaded: func(pkg *pkg, exports []stdlib.Symbol) {
			// If we're an x_test, load the package under test's test variant.
			if strings.HasSuffix(filePkg, "_test") && pkg.dir == filepath.Dir(filename) {
				var err error
				_, exports, err = loadExportsFromFiles(ctx, env, pkg.dir, true)
				if err != nil {
					return
				}
			}
			wrappedCallback.exportsLoaded(pkg, exports)
		},
	}
	resolver, err := env.GetResolver()
	if err != nil {
		return err
	}
	return resolver.scan(ctx, scanFilter)
}

func ScoreImportPaths(ctx context.Context, env *ProcessEnv, paths []string) (map[string]float64, error) {
	result := make(map[string]float64)
	resolver, err := env.GetResolver()
	if err != nil {
		return nil, err
	}
	for _, path := range paths {
		result[path] = resolver.scoreImportPath(ctx, path)
	}
	return result, nil
}

func PrimeCache(ctx context.Context, resolver Resolver) error {
	// Fully scan the disk for directories, but don't actually read any Go files.
	callback := &scanCallback{
		rootFound: func(root gopathwalk.Root) bool {
			// See getCandidatePkgs: walking GOROOT is apparently expensive and
			// unnecessary.
			return root.Type != gopathwalk.RootGOROOT
		},
		dirFound: func(pkg *pkg) bool {
			return false
		},
		// packageNameLoaded and exportsLoaded must never be called.
	}

	return resolver.scan(ctx, callback)
}

func candidateImportName(pkg *pkg) string {
	if ImportPathToAssumedName(pkg.importPathShort) != pkg.packageName {
		return pkg.packageName
	}
	return ""
}

// GetAllCandidates calls wrapped for each package whose name starts with
// searchPrefix, and can be imported from filename with the package name filePkg.
//
// Beware that the wrapped function may be called multiple times concurrently.
// TODO(adonovan): encapsulate the concurrency.
func GetAllCandidates(ctx context.Context, wrapped func(ImportFix), searchPrefix, filename, filePkg string, env *ProcessEnv) error {
	callback := &scanCallback{
		rootFound: func(gopathwalk.Root) bool {
			return true
		},
		dirFound: func(pkg *pkg) bool {
			if !CanUse(filename, pkg.dir) {
				return false
			}
			// Try the assumed package name first, then a simpler path match
			// in case of packages named vN, which are not uncommon.
			return strings.HasPrefix(ImportPathToAssumedName(pkg.importPathShort), searchPrefix) ||
				strings.HasPrefix(path.Base(pkg.importPathShort), searchPrefix)
		},
		packageNameLoaded: func(pkg *pkg) bool {
			if !strings.HasPrefix(pkg.packageName, searchPrefix) {
				return false
			}
			wrapped(ImportFix{
				StmtInfo: ImportInfo{
					ImportPath: pkg.importPathShort,
					Name:       candidateImportName(pkg),
				},
				IdentName: pkg.packageName,
				FixType:   AddImport,
				Relevance: pkg.relevance,
			})
			return false
		},
	}
	return getCandidatePkgs(ctx, callback, filename, filePkg, env)
}

// GetImportPaths calls wrapped for each package whose import path starts with
// searchPrefix, and can be imported from filename with the package name filePkg.
func GetImportPaths(ctx context.Context, wrapped func(ImportFix), searchPrefix, filename, filePkg string, env *ProcessEnv) error {
	callback := &scanCallback{
		rootFound: func(gopathwalk.Root) bool {
			return true
		},
		dirFound: func(pkg *pkg) bool {
			if !CanUse(filename, pkg.dir) {
				return false
			}
			return strings.HasPrefix(pkg.importPathShort, searchPrefix)
		},
		packageNameLoaded: func(pkg *pkg) bool {
			wrapped(ImportFix{
				StmtInfo: ImportInfo{
					ImportPath: pkg.importPathShort,
					Name:       candidateImportName(pkg),
				},
				IdentName: pkg.packageName,
				FixType:   AddImport,
				Relevance: pkg.relevance,
			})
			return false
		},
	}
	return getCandidatePkgs(ctx, callback, filename, filePkg, env)
}

// A PackageExport is a package and its exports.
type PackageExport struct {
	Fix     *ImportFix
	Exports []stdlib.Symbol
}

// GetPackageExports returns all known packages with name pkg and their exports.
func GetPackageExports(ctx context.Context, wrapped func(PackageExport), searchPkg, filename, filePkg string, env *ProcessEnv) error {
	callback := &scanCallback{
		rootFound: func(gopathwalk.Root) bool {
			return true
		},
		dirFound: func(pkg *pkg) bool {
			return pkgIsCandidate(filename, References{searchPkg: nil}, pkg)
		},
		packageNameLoaded: func(pkg *pkg) bool {
			return pkg.packageName == searchPkg
		},
		exportsLoaded: func(pkg *pkg, exports []stdlib.Symbol) {
			sortSymbols(exports)
			wrapped(PackageExport{
				Fix: &ImportFix{
					StmtInfo: ImportInfo{
						ImportPath: pkg.importPathShort,
						Name:       candidateImportName(pkg),
					},
					IdentName: pkg.packageName,
					FixType:   AddImport,
					Relevance: pkg.relevance,
				},
				Exports: exports,
			})
		},
	}
	return getCandidatePkgs(ctx, callback, filename, filePkg, env)
}

// TODO(rfindley): we should depend on GOOS and GOARCH, to provide accurate
// imports when doing cross-platform development.
var requiredGoEnvVars = []string{
	"GO111MODULE",
	"GOFLAGS",
	"GOINSECURE",
	"GOMOD",
	"GOMODCACHE",
	"GONOPROXY",
	"GONOSUMDB",
	"GOPATH",
	"GOPROXY",
	"GOROOT",
	"GOSUMDB",
	"GOWORK",
}

// ProcessEnv contains environment variables and settings that affect the use of
// the go command, the go/build package, etc.
//
// ...a ProcessEnv *also* overwrites its Env along with derived state in the
// form of the resolver. And because it is lazily initialized, an env may just
// be broken and unusable, but there is no way for the caller to detect that:
// all queries will just fail.
//
// TODO(rfindley): refactor this package so that this type (perhaps renamed to
// just Env or Config) is an immutable configuration struct, to be exchanged
// for an initialized object via a constructor that returns an error. Perhaps
// the signature should be `func NewResolver(*Env) (*Resolver, error)`, where
// resolver is a concrete type used for resolving imports. Via this
// refactoring, we can avoid the need to call ProcessEnv.init and
// ProcessEnv.GoEnv everywhere, and implicitly fix all the places where this
// these are misused. Also, we'd delegate the caller the decision of how to
// handle a broken environment.
type ProcessEnv struct {
	GocmdRunner *gocommand.Runner

	BuildFlags []string
	ModFlag    string

	// SkipPathInScan returns true if the path should be skipped from scans of
	// the RootCurrentModule root type. The function argument is a clean,
	// absolute path.
	SkipPathInScan func(string) bool

	// Env overrides the OS environment, and can be used to specify
	// GOPROXY, GO111MODULE, etc. PATH cannot be set here, because
	// exec.Command will not honor it.
	// Specifying all of requiredGoEnvVars avoids a call to `go env`.
	Env map[string]string

	WorkingDir string

	// If Logf is non-nil, debug logging is enabled through this function.
	Logf func(format string, args ...any)

	// If set, ModCache holds a shared cache of directory info to use across
	// multiple ProcessEnvs.
	ModCache *DirInfoCache

	initialized bool // see TODO above

	// resolver and resolverErr are lazily evaluated (see GetResolver).
	// This is unclean, but see the big TODO in the docstring for ProcessEnv
	// above: for now, we can't be sure that the ProcessEnv is fully initialized.
	resolver    Resolver
	resolverErr error
}

func (e *ProcessEnv) goEnv() (map[string]string, error) {
	if err := e.init(); err != nil {
		return nil, err
	}
	return e.Env, nil
}

func (e *ProcessEnv) matchFile(dir, name string) (bool, error) {
	bctx, err := e.buildContext()
	if err != nil {
		return false, err
	}
	return bctx.MatchFile(dir, name)
}

// CopyConfig copies the env's configuration into a new env.
func (e *ProcessEnv) CopyConfig() *ProcessEnv {
	copy := &ProcessEnv{
		GocmdRunner: e.GocmdRunner,
		initialized: e.initialized,
		BuildFlags:  e.BuildFlags,
		Logf:        e.Logf,
		WorkingDir:  e.WorkingDir,
		resolver:    nil,
		Env:         map[string]string{},
	}
	maps.Copy(copy.Env, e.Env)
	return copy
}

func (e *ProcessEnv) init() error {
	if e.initialized {
		return nil
	}

	foundAllRequired := true
	for _, k := range requiredGoEnvVars {
		if _, ok := e.Env[k]; !ok {
			foundAllRequired = false
			break
		}
	}
	if foundAllRequired {
		e.initialized = true
		return nil
	}

	if e.Env == nil {
		e.Env = map[string]string{}
	}

	goEnv := map[string]string{}
	stdout, err := e.invokeGo(context.TODO(), "env", append([]string{"-json"}, requiredGoEnvVars...)...)
	if err != nil {
		return err
	}
	if err := json.Unmarshal(stdout.Bytes(), &goEnv); err != nil {
		return err
	}
	maps.Copy(e.Env, goEnv)
	e.initialized = true
	return nil
}

func (e *ProcessEnv) env() []string {
	var env []string // the gocommand package will prepend os.Environ.
	for k, v := range e.Env {
		env = append(env, k+"="+v)
	}
	return env
}

func (e *ProcessEnv) GetResolver() (Resolver, error) {
	if err := e.init(); err != nil {
		return nil, err
	}

	if e.resolver == nil && e.resolverErr == nil {
		// TODO(rfindley): we should only use a gopathResolver here if the working
		// directory is actually *in* GOPATH. (I seem to recall an open gopls issue
		// for this behavior, but I can't find it).
		//
		// For gopls, we can optionally explicitly choose a resolver type, since we
		// already know the view type.
		if e.Env["GOMOD"] == "" && (e.Env["GOWORK"] == "" || e.Env["GOWORK"] == "off") {
			e.resolver = newGopathResolver(e)
			e.logf("created gopath resolver")
		} else if r, err := newModuleResolver(e, e.ModCache); err != nil {
			e.resolverErr = err
			e.logf("failed to create module resolver: %v", err)
		} else {
			e.resolver = Resolver(r)
			e.logf("created module resolver")
		}
	}

	return e.resolver, e.resolverErr
}

// logf logs if e.Logf is non-nil.
func (e *ProcessEnv) logf(format string, args ...any) {
	if e.Logf != nil {
		e.Logf(format, args...)
	}
}

// buildContext returns the build.Context to use for matching files.
//
// TODO(rfindley): support dynamic GOOS, GOARCH here, when doing cross-platform
// development.
func (e *ProcessEnv) buildContext() (*build.Context, error) {
	ctx := build.Default
	goenv, err := e.goEnv()
	if err != nil {
		return nil, err
	}
	ctx.GOROOT = goenv["GOROOT"]
	ctx.GOPATH = goenv["GOPATH"]

	// As of Go 1.14, build.Context has a Dir field
	// (see golang.org/issue/34860).
	// Populate it only if present.
	rc := reflect.ValueOf(&ctx).Elem()
	dir := rc.FieldByName("Dir")
	if dir.IsValid() && dir.Kind() == reflect.String {
		dir.SetString(e.WorkingDir)
	}

	// Since Go 1.11, go/build.Context.Import may invoke 'go list' depending on
	// the value in GO111MODULE in the process's environment. We always want to
	// run in GOPATH mode when calling Import, so we need to prevent this from
	// happening. In Go 1.16, GO111MODULE defaults to "on", so this problem comes
	// up more frequently.
	//
	// HACK: setting any of the Context I/O hooks prevents Import from invoking
	// 'go list', regardless of GO111MODULE. This is undocumented, but it's
	// unlikely to change before GOPATH support is removed.
	ctx.ReadDir = ioutil.ReadDir

	return &ctx, nil
}

func (e *ProcessEnv) invokeGo(ctx context.Context, verb string, args ...string) (*bytes.Buffer, error) {
	inv := gocommand.Invocation{
		Verb:       verb,
		Args:       args,
		BuildFlags: e.BuildFlags,
		Env:        e.env(),
		Logf:       e.Logf,
		WorkingDir: e.WorkingDir,
	}
	return e.GocmdRunner.Run(ctx, inv)
}

func addStdlibCandidates(pass *pass, refs References) error {
	localbase := func(nm string) string {
		ans := path.Base(nm)
		if ans[0] == 'v' {
			// this is called, for instance, with math/rand/v2 and returns rand/v2
			if _, err := strconv.Atoi(ans[1:]); err == nil {
				ix := strings.LastIndex(nm, ans)
				more := path.Base(nm[:ix])
				ans = path.Join(more, ans)
			}
		}
		return ans
	}
	add := func(pkg string) {
		// Prevent self-imports.
		if path.Base(pkg) == pass.f.Name.Name && filepath.Join(pass.goroot, "src", pkg) == pass.srcDir {
			return
		}
		exports := symbolNameSet(stdlib.PackageSymbols[pkg])
		pass.addCandidate(
			&ImportInfo{ImportPath: pkg},
			&PackageInfo{Name: localbase(pkg), Exports: exports})
	}
	for left := range refs {
		if left == "rand" {
			// Make sure we try crypto/rand before any version of math/rand as both have Int()
			// and our policy is to recommend crypto
			add("crypto/rand")
			// if the user's no later than go1.21, this should be "math/rand"
			// but we have no way of figuring out what the user is using
			// TODO: investigate using the toolchain version to disambiguate in the stdlib
			add("math/rand/v2")
			// math/rand has an overlapping API
			// TestIssue66407 fails without this
			add("math/rand")
			continue
		}
		for importPath := range stdlib.PackageSymbols {
			if path.Base(importPath) == left {
				add(importPath)
			}
		}
	}
	return nil
}

// A Resolver does the build-system-specific parts of goimports.
type Resolver interface {
	// loadPackageNames loads the package names in importPaths.
	loadPackageNames(importPaths []string, srcDir string) (map[string]string, error)

	// scan works with callback to search for packages. See scanCallback for details.
	scan(ctx context.Context, callback *scanCallback) error

	// loadExports returns the package name and set of exported symbols in the
	// package at dir. loadExports may be called concurrently.
	loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []stdlib.Symbol, error)

	// scoreImportPath returns the relevance for an import path.
	scoreImportPath(ctx context.Context, path string) float64

	// ClearForNewScan returns a new Resolver based on the receiver that has
	// cleared its internal caches of directory contents.
	//
	// The new resolver should be primed and then set via
	// [ProcessEnv.UpdateResolver].
	ClearForNewScan() Resolver
}

// A scanCallback controls a call to scan and receives its results.
// In general, minor errors will be silently discarded; a user should not
// expect to receive a full series of calls for everything.
type scanCallback struct {
	// rootFound is called before scanning a new root dir. If it returns true,
	// the root will be scanned. Returning false will not necessarily prevent
	// directories from that root making it to dirFound.
	rootFound func(gopathwalk.Root) bool
	// dirFound is called when a directory is found that is possibly a Go package.
	// pkg will be populated with everything except packageName.
	// If it returns true, the package's name will be loaded.
	dirFound func(pkg *pkg) bool
	// packageNameLoaded is called when a package is found and its name is loaded.
	// If it returns true, the package's exports will be loaded.
	packageNameLoaded func(pkg *pkg) bool
	// exportsLoaded is called when a package's exports have been loaded.
	exportsLoaded func(pkg *pkg, exports []stdlib.Symbol)
}

func addExternalCandidates(ctx context.Context, pass *pass, refs References, filename string) error {
	ctx, done := event.Start(ctx, "imports.addExternalCandidates")
	defer done()

	results, err := pass.source.ResolveReferences(ctx, filename, refs)
	if err != nil {
		return err
	}

	for _, result := range results {
		if result == nil {
			continue
		}
		// Don't offer completions that would shadow predeclared
		// names, such as github.com/coreos/etcd/error.
		if types.Universe.Lookup(result.Package.Name) != nil { // predeclared
			// Ideally we would skip this candidate only
			// if the predeclared name is actually
			// referenced by the file, but that's a lot
			// trickier to compute and would still create
			// an import that is likely to surprise the
			// user before long.
			continue
		}
		pass.addCandidate(result.Import, result.Package)
	}
	return nil
}

// notIdentifier reports whether ch is an invalid identifier character.
func notIdentifier(ch rune) bool {
	return !('a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' ||
		'0' <= ch && ch <= '9' ||
		ch == '_' ||
		ch >= utf8.RuneSelf && (unicode.IsLetter(ch) || unicode.IsDigit(ch)))
}

// ImportPathToAssumedName returns the assumed package name of an import path.
// It does this using only string parsing of the import path.
// It picks the last element of the path that does not look like a major
// version, and then picks the valid identifier off the start of that element.
// It is used to determine if a local rename should be added to an import for
// clarity.
// This function could be moved to a standard package and exported if we want
// for use in other tools.
func ImportPathToAssumedName(importPath string) string {
	base := path.Base(importPath)
	if strings.HasPrefix(base, "v") {
		if _, err := strconv.Atoi(base[1:]); err == nil {
			dir := path.Dir(importPath)
			if dir != "." {
				base = path.Base(dir)
			}
		}
	}
	base = strings.TrimPrefix(base, "go-")
	if i := strings.IndexFunc(base, notIdentifier); i >= 0 {
		base = base[:i]
	}
	return base
}

// gopathResolver implements resolver for GOPATH workspaces.
type gopathResolver struct {
	env      *ProcessEnv
	cache    *DirInfoCache
	scanSema chan struct{} // scanSema prevents concurrent scans.
}

func newGopathResolver(env *ProcessEnv) *gopathResolver {
	r := &gopathResolver{
		env:      env,
		cache:    NewDirInfoCache(),
		scanSema: make(chan struct{}, 1),
	}
	r.scanSema <- struct{}{}
	return r
}

func (r *gopathResolver) ClearForNewScan() Resolver {
	return newGopathResolver(r.env)
}

func (r *gopathResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
	names := map[string]string{}
	bctx, err := r.env.buildContext()
	if err != nil {
		return nil, err
	}
	for _, path := range importPaths {
		names[path] = importPathToName(bctx, path, srcDir)
	}
	return names, nil
}

// importPathToName finds out the actual package name, as declared in its .go files.
func importPathToName(bctx *build.Context, importPath, srcDir string) string {
	// Fast path for standard library without going to disk.
	if stdlib.HasPackage(importPath) {
		return path.Base(importPath) // stdlib packages always match their paths.
	}

	buildPkg, err := bctx.Import(importPath, srcDir, build.FindOnly)
	if err != nil {
		return ""
	}
	pkgName, err := packageDirToName(buildPkg.Dir)
	if err != nil {
		return ""
	}
	return pkgName
}

// packageDirToName is a faster version of build.Import if
// the only thing desired is the package name. Given a directory,
// packageDirToName then only parses one file in the package,
// trusting that the files in the directory are consistent.
func packageDirToName(dir string) (packageName string, err error) {
	d, err := os.Open(dir)
	if err != nil {
		return "", err
	}
	names, err := d.Readdirnames(-1)
	d.Close()
	if err != nil {
		return "", err
	}
	sort.Strings(names) // to have predictable behavior
	var lastErr error
	var nfile int
	for _, name := range names {
		if !strings.HasSuffix(name, ".go") {
			continue
		}
		if strings.HasSuffix(name, "_test.go") {
			continue
		}
		nfile++
		fullFile := filepath.Join(dir, name)

		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, fullFile, nil, parser.PackageClauseOnly)
		if err != nil {
			lastErr = err
			continue
		}
		pkgName := f.Name.Name
		if pkgName == "documentation" {
			// Special case from go/build.ImportDir, not
			// handled by ctx.MatchFile.
			continue
		}
		if pkgName == "main" {
			// Also skip package main, assuming it's a +build ignore generator or example.
			// Since you can't import a package main anyway, there's no harm here.
			continue
		}
		return pkgName, nil
	}
	if lastErr != nil {
		return "", lastErr
	}
	return "", fmt.Errorf("no importable package found in %d Go files", nfile)
}

type pkg struct {
	dir             string  // absolute file path to pkg directory ("/usr/lib/go/src/net/http")
	importPathShort string  // vendorless import path ("net/http", "a/b")
	packageName     string  // package name loaded from source if requested
	relevance       float64 // a weakly-defined score of how relevant a package is. 0 is most relevant.
}

type pkgDistance struct {
	pkg      *pkg
	distance int // relative distance to target
}

// byDistanceOrImportPathShortLength sorts by relative distance breaking ties
// on the short import path length and then the import string itself.
type byDistanceOrImportPathShortLength []pkgDistance

func (s byDistanceOrImportPathShortLength) Len() int { return len(s) }
func (s byDistanceOrImportPathShortLength) Less(i, j int) bool {
	di, dj := s[i].distance, s[j].distance
	if di == -1 {
		return false
	}
	if dj == -1 {
		return true
	}
	if di != dj {
		return di < dj
	}

	vi, vj := s[i].pkg.importPathShort, s[j].pkg.importPathShort
	if len(vi) != len(vj) {
		return len(vi) < len(vj)
	}
	return vi < vj
}
func (s byDistanceOrImportPathShortLength) Swap(i, j int) { s[i], s[j] = s[j], s[i] }

func distance(basepath, targetpath string) int {
	p, err := filepath.Rel(basepath, targetpath)
	if err != nil {
		return -1
	}
	if p == "." {
		return 0
	}
	return strings.Count(p, string(filepath.Separator)) + 1
}

func (r *gopathResolver) scan(ctx context.Context, callback *scanCallback) error {
	add := func(root gopathwalk.Root, dir string) {
		// We assume cached directories have not changed. We can skip them and their
		// children.
		if _, ok := r.cache.Load(dir); ok {
			return
		}

		importpath := filepath.ToSlash(dir[len(root.Path)+len("/"):])
		info := directoryPackageInfo{
			status:                 directoryScanned,
			dir:                    dir,
			rootType:               root.Type,
			nonCanonicalImportPath: VendorlessPath(importpath),
		}
		r.cache.Store(dir, info)
	}
	processDir := func(info directoryPackageInfo) {
		// Skip this directory if we were not able to get the package information successfully.
		if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
			return
		}

		p := &pkg{
			importPathShort: info.nonCanonicalImportPath,
			dir:             info.dir,
			relevance:       MaxRelevance - 1,
		}
		if info.rootType == gopathwalk.RootGOROOT {
			p.relevance = MaxRelevance
		}

		if !callback.dirFound(p) {
			return
		}
		var err error
		p.packageName, err = r.cache.CachePackageName(info)
		if err != nil {
			return
		}

		if !callback.packageNameLoaded(p) {
			return
		}
		if _, exports, err := r.loadExports(ctx, p, false); err == nil {
			callback.exportsLoaded(p, exports)
		}
	}
	stop := r.cache.ScanAndListen(ctx, processDir)
	defer stop()

	goenv, err := r.env.goEnv()
	if err != nil {
		return err
	}
	var roots []gopathwalk.Root
	roots = append(roots, gopathwalk.Root{Path: filepath.Join(goenv["GOROOT"], "src"), Type: gopathwalk.RootGOROOT})
	for _, p := range filepath.SplitList(goenv["GOPATH"]) {
		roots = append(roots, gopathwalk.Root{Path: filepath.Join(p, "src"), Type: gopathwalk.RootGOPATH})
	}
	// The callback is not necessarily safe to use in the goroutine below. Process roots eagerly.
	roots = filterRoots(roots, callback.rootFound)
	// We can't cancel walks, because we need them to finish to have a usable
	// cache. Instead, run them in a separate goroutine and detach.
	scanDone := make(chan struct{})
	go func() {
		select {
		case <-ctx.Done():
			return
		case <-r.scanSema:
		}
		defer func() { r.scanSema <- struct{}{} }()
		gopathwalk.Walk(roots, add, gopathwalk.Options{Logf: r.env.Logf, ModulesEnabled: false})
		close(scanDone)
	}()
	select {
	case <-ctx.Done():
	case <-scanDone:
	}
	return nil
}

func (r *gopathResolver) scoreImportPath(ctx context.Context, path string) float64 {
	if stdlib.HasPackage(path) {
		return MaxRelevance
	}
	return MaxRelevance - 1
}

func filterRoots(roots []gopathwalk.Root, include func(gopathwalk.Root) bool) []gopathwalk.Root {
	var result []gopathwalk.Root
	for _, root := range roots {
		if !include(root) {
			continue
		}
		result = append(result, root)
	}
	return result
}

func (r *gopathResolver) loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []stdlib.Symbol, error) {
	if info, ok := r.cache.Load(pkg.dir); ok && !includeTest {
		return r.cache.CacheExports(ctx, r.env, info)
	}
	return loadExportsFromFiles(ctx, r.env, pkg.dir, includeTest)
}

// VendorlessPath returns the devendorized version of the import path ipath.
// For example, VendorlessPath("foo/bar/vendor/a/b") returns "a/b".
func VendorlessPath(ipath string) string {
	// Devendorize for use in import statement.
	if i := strings.LastIndex(ipath, "/vendor/"); i >= 0 {
		return ipath[i+len("/vendor/"):]
	}
	if strings.HasPrefix(ipath, "vendor/") {
		return ipath[len("vendor/"):]
	}
	return ipath
}

func loadExportsFromFiles(ctx context.Context, env *ProcessEnv, dir string, includeTest bool) (string, []stdlib.Symbol, error) {
	// Look for non-test, buildable .go files which could provide exports.
	all, err := os.ReadDir(dir)
	if err != nil {
		return "", nil, err
	}
	var files []fs.DirEntry
	for _, fi := range all {
		name := fi.Name()
		if !strings.HasSuffix(name, ".go") || (!includeTest && strings.HasSuffix(name, "_test.go")) {
			continue
		}
		match, err := env.matchFile(dir, fi.Name())
		if err != nil || !match {
			continue
		}
		files = append(files, fi)
	}

	if len(files) == 0 {
		return "", nil, fmt.Errorf("dir %v contains no buildable, non-test .go files", dir)
	}

	var pkgName string
	var exports []stdlib.Symbol
	fset := token.NewFileSet()
	for _, fi := range files {
		select {
		case <-ctx.Done():
			return "", nil, ctx.Err()
		default:
		}

		fullFile := filepath.Join(dir, fi.Name())
		// Legacy ast.Object resolution is needed here.
		f, err := parser.ParseFile(fset, fullFile, nil, 0)
		if err != nil {
			env.logf("error parsing %v: %v", fullFile, err)
			continue
		}
		if f.Name.Name == "documentation" {
			// Special case from go/build.ImportDir, not
			// handled by MatchFile above.
			continue
		}
		if includeTest && strings.HasSuffix(f.Name.Name, "_test") {
			// x_test package. We want internal test files only.
			continue
		}
		pkgName = f.Name.Name
		for name, obj := range f.Scope.Objects {
			if ast.IsExported(name) {
				var kind stdlib.Kind
				switch obj.Kind {
				case ast.Con:
					kind = stdlib.Const
				case ast.Typ:
					kind = stdlib.Type
				case ast.Var:
					kind = stdlib.Var
				case ast.Fun:
					kind = stdlib.Func
				}
				exports = append(exports, stdlib.Symbol{
					Name:    name,
					Kind:    kind,
					Version: 0, // unknown; be permissive
				})
			}
		}
	}
	sortSymbols(exports)

	env.logf("loaded exports in dir %v (package %v): %v", dir, pkgName, exports)
	return pkgName, exports, nil
}

func sortSymbols(syms []stdlib.Symbol) {
	sort.Slice(syms, func(i, j int) bool {
		return syms[i].Name < syms[j].Name
	})
}

// A symbolSearcher searches for a package with a set of symbols, among a set
// of candidates. See [symbolSearcher.search].
//
// The search occurs within the scope of a single file, with context captured
// in srcDir and xtest.
type symbolSearcher struct {
	logf        func(string, ...any)
	srcDir      string // directory containing the file
	xtest       bool   // if set, the file containing is an x_test file
	loadExports func(ctx context.Context, pkg *pkg, includeTest bool) (string, []stdlib.Symbol, error)
}

// search searches the provided candidates for a package containing all
// exported symbols.
//
// If successful, returns the resulting package.
func (s *symbolSearcher) search(ctx context.Context, candidates []pkgDistance, pkgName string, symbols map[string]bool) (*pkg, error) {
	// Sort the candidates by their import package length,
	// assuming that shorter package names are better than long
	// ones.  Note that this sorts by the de-vendored name, so
	// there's no "penalty" for vendoring.
	sort.Sort(byDistanceOrImportPathShortLength(candidates))
	if s.logf != nil {
		for i, c := range candidates {
			s.logf("%s candidate %d/%d: %v in %v", pkgName, i+1, len(candidates), c.pkg.importPathShort, c.pkg.dir)
		}
	}

	// Arrange rescv so that we can we can await results in order of relevance
	// and exit as soon as we find the first match.
	//
	// Search with bounded concurrency, returning as soon as the first result
	// among rescv is non-nil.
	rescv := make([]chan *pkg, len(candidates))
	for i := range candidates {
		rescv[i] = make(chan *pkg, 1)
	}
	const maxConcurrentPackageImport = 4
	loadExportsSem := make(chan struct{}, maxConcurrentPackageImport)

	// Ensure that all work is completed at exit.
	ctx, cancel := context.WithCancel(ctx)
	var wg sync.WaitGroup
	defer func() {
		cancel()
		wg.Wait()
	}()

	// Start the search.
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i, c := range candidates {
			select {
			case loadExportsSem <- struct{}{}:
			case <-ctx.Done():
				return
			}

			i := i
			c := c
			wg.Add(1)
			go func() {
				defer func() {
					<-loadExportsSem
					wg.Done()
				}()
				if s.logf != nil {
					s.logf("loading exports in dir %s (seeking package %s)", c.pkg.dir, pkgName)
				}
				pkg, err := s.searchOne(ctx, c, symbols)
				if err != nil {
					if s.logf != nil && ctx.Err() == nil {
						s.logf("loading exports in dir %s (seeking package %s): %v", c.pkg.dir, pkgName, err)
					}
					pkg = nil
				}
				rescv[i] <- pkg // may be nil
			}()
		}
	}()

	// Await the first (best) result.
	for _, resc := range rescv {
		select {
		case r := <-resc:
			if r != nil {
				return r, nil
			}
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	}
	return nil, nil
}

func (s *symbolSearcher) searchOne(ctx context.Context, c pkgDistance, symbols map[string]bool) (*pkg, error) {
	if ctx.Err() != nil {
		return nil, ctx.Err()
	}
	// If we're considering the package under test from an x_test, load the
	// test variant.
	includeTest := s.xtest && c.pkg.dir == s.srcDir
	_, exports, err := s.loadExports(ctx, c.pkg, includeTest)
	if err != nil {
		return nil, err
	}

	exportsMap := make(map[string]bool, len(exports))
	for _, sym := range exports {
		exportsMap[sym.Name] = true
	}
	for symbol := range symbols {
		if !exportsMap[symbol] {
			return nil, nil // no match
		}
	}
	return c.pkg, nil
}

// pkgIsCandidate reports whether pkg is a candidate for satisfying the
// finding which package pkgIdent in the file named by filename is trying
// to refer to.
//
// This check is purely lexical and is meant to be as fast as possible
// because it's run over all $GOPATH directories to filter out poor
// candidates in order to limit the CPU and I/O later parsing the
// exports in candidate packages.
//
// filename is the file being formatted.
// pkgIdent is the package being searched for, like "client" (if
// searching for "client.New")
func pkgIsCandidate(filename string, refs References, pkg *pkg) bool {
	// Check "internal" and "vendor" visibility:
	if !CanUse(filename, pkg.dir) {
		return false
	}

	// Speed optimization to minimize disk I/O:
	//
	// Use the matchesPath heuristic to filter to package paths that could
	// reasonably match a dangling reference.
	//
	// This permits mismatch naming like directory "go-foo" being package "foo",
	// or "pkg.v3" being "pkg", or directory
	// "google.golang.org/api/cloudbilling/v1" being package "cloudbilling", but
	// doesn't permit a directory "foo" to be package "bar", which is strongly
	// discouraged anyway. There's no reason goimports needs to be slow just to
	// accommodate that.
	for pkgIdent := range refs {
		if matchesPath(pkgIdent, pkg.importPathShort) {
			return true
		}
	}
	return false
}

// CanUse reports whether the package in dir is usable from filename,
// respecting the Go "internal" and "vendor" visibility rules.
func CanUse(filename, dir string) bool {
	// Fast path check, before any allocations. If it doesn't contain vendor
	// or internal, it's not tricky:
	// Note that this can false-negative on directories like "notinternal",
	// but we check it correctly below. This is just a fast path.
	if !strings.Contains(dir, "vendor") && !strings.Contains(dir, "internal") {
		return true
	}

	dirSlash := filepath.ToSlash(dir)
	if !strings.Contains(dirSlash, "/vendor/") && !strings.Contains(dirSlash, "/internal/") && !strings.HasSuffix(dirSlash, "/internal") {
		return true
	}
	// Vendor or internal directory only visible from children of parent.
	// That means the path from the current directory to the target directory
	// can contain ../vendor or ../internal but not ../foo/vendor or ../foo/internal
	// or bar/vendor or bar/internal.
	// After stripping all the leading ../, the only okay place to see vendor or internal
	// is at the very beginning of the path.
	absfile, err := filepath.Abs(filename)
	if err != nil {
		return false
	}
	absdir, err := filepath.Abs(dir)
	if err != nil {
		return false
	}
	rel, err := filepath.Rel(absfile, absdir)
	if err != nil {
		return false
	}
	relSlash := filepath.ToSlash(rel)
	if i := strings.LastIndex(relSlash, "../"); i >= 0 {
		relSlash = relSlash[i+len("../"):]
	}
	return !strings.Contains(relSlash, "/vendor/") && !strings.Contains(relSlash, "/internal/") && !strings.HasSuffix(relSlash, "/internal")
}

// matchesPath reports whether ident may match a potential package name
// referred to by path, using heuristics to filter out unidiomatic package
// names.
//
// Specifically, it checks whether either of the last two '/'- or '\'-delimited
// path segments matches the identifier. The segment-matching heuristic must
// allow for various conventions around segment naming, including go-foo,
// foo-go, and foo.v3. To handle all of these, matching considers both (1) the
// entire segment, ignoring '-' and '.', as well as (2) the last subsegment
// separated by '-' or '.'. So the segment foo-go matches all of the following
// identifiers: foo, go, and foogo. All matches are case insensitive (for ASCII
// identifiers).
//
// See the docstring for [pkgIsCandidate] for an explanation of how this
// heuristic filters potential candidate packages.
func matchesPath(ident, path string) bool {
	// Ignore case, for ASCII.
	lowerIfASCII := func(b byte) byte {
		if 'A' <= b && b <= 'Z' {
			return b + ('a' - 'A')
		}
		return b
	}

	// match reports whether path[start:end] matches ident, ignoring [.-].
	match := func(start, end int) bool {
		ii := len(ident) - 1 // current byte in ident
		pi := end - 1        // current byte in path
		for ; pi >= start && ii >= 0; pi-- {
			pb := path[pi]
			if pb == '-' || pb == '.' {
				continue
			}
			pb = lowerIfASCII(pb)
			ib := lowerIfASCII(ident[ii])
			if pb != ib {
				return false
			}
			ii--
		}
		return ii < 0 && pi < start // all bytes matched
	}

	// segmentEnd and subsegmentEnd hold the end points of the current segment
	// and subsegment intervals.
	segmentEnd := len(path)
	subsegmentEnd := len(path)

	// Count slashes; we only care about the last two segments.
	nslash := 0

	for i := len(path) - 1; i >= 0; i-- {
		switch b := path[i]; b {
		// TODO(rfindley): we handle backlashes here only because the previous
		// heuristic handled backslashes. This is perhaps overly defensive, but is
		// the result of many lessons regarding Chesterton's fence and the
		// goimports codebase.
		//
		// However, this function is only ever called with something called an
		// 'importPath'. Is it possible that this is a real import path, and
		// therefore we need only consider forward slashes?
		case '/', '\\':
			if match(i+1, segmentEnd) || match(i+1, subsegmentEnd) {
				return true
			}
			nslash++
			if nslash == 2 {
				return false // did not match above
			}
			segmentEnd, subsegmentEnd = i, i // reset
		case '-', '.':
			if match(i+1, subsegmentEnd) {
				return true
			}
			subsegmentEnd = i
		}
	}
	return match(0, segmentEnd) || match(0, subsegmentEnd)
}

type visitFn func(node ast.Node) ast.Visitor

func (fn visitFn) Visit(node ast.Node) ast.Visitor {
	return fn(node)
}

func symbolNameSet(symbols []stdlib.Symbol) map[string]bool {
	names := make(map[string]bool)
	for _, sym := range symbols {
		switch sym.Kind {
		case stdlib.Const, stdlib.Var, stdlib.Type, stdlib.Func:
			names[sym.Name] = true
		}
	}
	return names
}


================================================
FILE: internal/imports/fix_test.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"context"
	"flag"
	"fmt"
	"go/build"
	"log"
	"os"
	"path"
	"path/filepath"
	"reflect"
	"sort"
	"strings"
	"sync"
	"sync/atomic"
	"testing"

	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/packagestest"
	"golang.org/x/tools/internal/stdlib"
)

var testDebug = flag.Bool("debug", false, "enable debug output")

var tests = []struct {
	name       string
	formatOnly bool
	in, out    string
}{
	// Adding an import to an existing parenthesized import
	{
		name: "factored_imports_add",
		in: `package foo
import (
  "fmt"
)
func bar() {
var b bytes.Buffer
fmt.Println(b.String())
}
`,
		out: `package foo

import (
	"bytes"
	"fmt"
)

func bar() {
	var b bytes.Buffer
	fmt.Println(b.String())
}
`,
	},

	// Adding an import to an existing parenthesized import,
	// verifying it goes into the first section.
	{
		name: "factored_imports_add_first_sec",
		in: `package foo
import (
  "fmt"

  "github.com/golang/snappy"
)
func bar() {
var b bytes.Buffer
_ = snappy.ErrCorrupt
fmt.Println(b.String())
}
`,
		out: `package foo

import (
	"bytes"
	"fmt"

	"github.com/golang/snappy"
)

func bar() {
	var b bytes.Buffer
	_ = snappy.ErrCorrupt
	fmt.Println(b.String())
}
`,
	},

	// Adding an import to an existing parenthesized import,
	// verifying it goes into the first section. (test 2)
	{
		name: "factored_imports_add_first_sec_2",
		in: `package foo
import (
  "fmt"

  "github.com/golang/snappy"
)
func bar() {
_ = math.NaN
_ = fmt.Sprintf
_ = snappy.ErrCorrupt
}
`,
		out: `package foo

import (
	"fmt"
	"math"

	"github.com/golang/snappy"
)

func bar() {
	_ = math.NaN
	_ = fmt.Sprintf
	_ = snappy.ErrCorrupt
}
`,
	},

	// Adding a new import line, without parens
	{
		name: "add_import_section",
		in: `package foo
func bar() {
var b bytes.Buffer
}
`,
		out: `package foo

import "bytes"

func bar() {
	var b bytes.Buffer
}
`,
	},

	// Adding two new imports, which should make a parenthesized import decl.
	{
		name: "add_import_paren_section",
		in: `package foo
func bar() {
_, _ := bytes.Buffer, zip.NewReader
}
`,
		out: `package foo

import (
	"archive/zip"
	"bytes"
)

func bar() {
	_, _ := bytes.Buffer, zip.NewReader
}
`,
	},

	// Make sure we don't add things twice
	{
		name: "no_double_add",
		in: `package foo
func bar() {
_, _ := bytes.Buffer, bytes.NewReader
}
`,
		out: `package foo

import "bytes"

func bar() {
	_, _ := bytes.Buffer, bytes.NewReader
}
`,
	},

	// Make sure we don't add packages that don't have the right exports
	{
		name: "no_mismatched_add",
		in: `package foo

func bar() {
	_ := bytes.NonexistentSymbol
}
`,
		out: `package foo

func bar() {
	_ := bytes.NonexistentSymbol
}
`,
	},

	// Remove unused imports, 1 of a factored block
	{
		name: "remove_unused_1_of_2",
		in: `package foo
import (
"bytes"
"fmt"
)

func bar() {
_, _ := bytes.Buffer, bytes.NewReader
}
`,
		out: `package foo

import (
	"bytes"
)

func bar() {
	_, _ := bytes.Buffer, bytes.NewReader
}
`,
	},

	// Remove unused imports, 2 of 2
	{
		name: "remove_unused_2_of_2",
		in: `package foo
import (
"bytes"
"fmt"
)

func bar() {
}
`,
		out: `package foo

func bar() {
}
`,
	},

	// Remove unused imports, 1 of 1
	{
		name: "remove_unused_1_of_1",
		in: `package foo

import "fmt"

func bar() {
}
`,
		out: `package foo

func bar() {
}
`,
	},

	// Don't remove empty imports.
	{
		name: "dont_remove_empty_imports",
		in: `package foo
import (
_ "image/png"
_ "image/jpeg"
)
`,
		out: `package foo

import (
	_ "image/jpeg"
	_ "image/png"
)
`,
	},

	// Don't remove dot imports.
	{
		name: "dont_remove_dot_imports",
		in: `package foo
import (
. "foo"
. "bar"
)
`,
		out: `package foo

import (
	. "bar"
	. "foo"
)
`,
	},

	// Skip refs the parser can resolve.
	{
		name: "skip_resolved_refs",
		in: `package foo

func f() {
	type t struct{ Println func(string) }
	fmt := t{Println: func(string) {}}
	fmt.Println("foo")
}
`,
		out: `package foo

func f() {
	type t struct{ Println func(string) }
	fmt := t{Println: func(string) {}}
	fmt.Println("foo")
}
`,
	},

	// Do not add a package we already have a resolution for.
	{
		name: "skip_template",
		in: `package foo

import "html/template"

func f() { t = template.New("sometemplate") }
`,
		out: `package foo

import "html/template"

func f() { t = template.New("sometemplate") }
`,
	},

	// Don't touch cgo
	{
		name: "cgo",
		in: `package foo

/*
#include <foo.h>
*/
import "C"
`,
		out: `package foo

/*
#include <foo.h>
*/
import "C"
`,
	},

	// Put some things in their own section
	{
		name: "make_sections",
		in: `package foo

import (
"os"
)

func foo () {
_, _ = os.Args, fmt.Println
_, _ = snappy.ErrCorrupt, p.P
}
`,
		out: `package foo

import (
	"fmt"
	"os"

	"github.com/golang/snappy"
	"rsc.io/p"
)

func foo() {
	_, _ = os.Args, fmt.Println
	_, _ = snappy.ErrCorrupt, p.P
}
`,
	},
	// Merge import blocks, even when no additions are required.
	{
		name: "merge_import_blocks_no_fix",
		in: `package foo

import (
	"fmt"
)
import "os"

import (
	"rsc.io/p"
)

var _, _ = os.Args, fmt.Println
var _, _ = snappy.ErrCorrupt, p.P
`,
		out: `package foo

import (
	"fmt"
	"os"

	"github.com/golang/snappy"
	"rsc.io/p"
)

var _, _ = os.Args, fmt.Println
var _, _ = snappy.ErrCorrupt, p.P
`,
	},
	// Delete existing empty import block
	{
		name: "delete_empty_import_block",
		in: `package foo

import ()
`,
		out: `package foo
`,
	},

	// Use existing empty import block
	{
		name: "use_empty_import_block",
		in: `package foo

import ()

func f() {
	_ = fmt.Println
}
`,
		out: `package foo

import "fmt"

func f() {
	_ = fmt.Println
}
`,
	},

	// Blank line before adding new section.
	{
		name: "blank_line_before_new_group",
		in: `package foo

import (
	"fmt"
	"net"
)

func f() {
	_ = net.Dial
	_ = fmt.Printf
	_ = snappy.ErrCorrupt
}
`,
		out: `package foo

import (
	"fmt"
	"net"

	"github.com/golang/snappy"
)

func f() {
	_ = net.Dial
	_ = fmt.Printf
	_ = snappy.ErrCorrupt
}
`,
	},

	// Blank line between standard library and third-party stuff.
	{
		name: "blank_line_separating_std_and_third_party",
		in: `package foo

import (
	"github.com/golang/snappy"
	"fmt"
	"net"
)

func f() {
	_ = net.Dial
	_ = fmt.Printf
	_ = snappy.Foo
}
`,
		out: `package foo

import (
	"fmt"
	"net"

	"github.com/golang/snappy"
)

func f() {
	_ = net.Dial
	_ = fmt.Printf
	_ = snappy.Foo
}
`,
	},

	// golang.org/issue/6884
	{
		name: "new_imports_before_comment",
		in: `package main

// A comment
func main() {
	fmt.Println("Hello, world")
}
`,
		out: `package main

import "fmt"

// A comment
func main() {
	fmt.Println("Hello, world")
}
`,
	},

	// golang.org/issue/7132
	{
		name: "new_section_for_dotless_import",
		in: `package main

import (
"fmt"

"gu"
"manypackages.com/packagea"
)

var (
a = packagea.A
b = gu.A
c = fmt.Printf
)
`,
		out: `package main

import (
	"fmt"

	"gu"

	"manypackages.com/packagea"
)

var (
	a = packagea.A
	b = gu.A
	c = fmt.Printf
)
`,
	},

	{
		name: "fragment_with_main",
		in:   `func main(){fmt.Println("Hello, world")}`,
		out: `package main

import "fmt"

func main() { fmt.Println("Hello, world") }
`,
	},

	{
		name: "fragment_without_main",
		in:   `func notmain(){fmt.Println("Hello, world")}`,
		out: `import "fmt"

func notmain() { fmt.Println("Hello, world") }`,
	},

	// Remove first import within in a 2nd/3rd/4th/etc. section.
	// golang.org/issue/7679
	{
		name: "remove_first_import_in_section",
		in: `package main

import (
	"fmt"

	"manypackages.com/packagea"
	"manypackages.com/packageb"
)

func main() {
	var _ = fmt.Println
	//var _ = packagea.A
	var _ = packageb.B
}
`,
		out: `package main

import (
	"fmt"

	"manypackages.com/packageb"
)

func main() {
	var _ = fmt.Println
	//var _ = packagea.A
	var _ = packageb.B
}
`,
	},

	// Blank line can be added before all types of import declarations.
	// golang.org/issue/7866
	{
		name: "new_section_for_all_kinds_of_imports",
		in: `package main

import (
	"fmt"
	renamed_packagea "manypackages.com/packagea"

	. "manypackages.com/packageb"
	"io"

	_ "manypackages.com/packagec"
	"strings"
)

var _, _, _, _, _ = fmt.Errorf, io.Copy, strings.Contains, renamed_packagea.A, B
`,
		out: `package main

import (
	"fmt"

	renamed_packagea "manypackages.com/packagea"

	"io"

	. "manypackages.com/packageb"

	"strings"

	_ "manypackages.com/packagec"
)

var _, _, _, _, _ = fmt.Errorf, io.Copy, strings.Contains, renamed_packagea.A, B
`,
	},

	// Blank line can be added even when first import of group has comment with quote
	{
		name: "new_section_where_trailing_comment_has_quote",
		in: `package main

import (
	"context"
	bar "local.com/bar"
	baz "local.com/baz"
	buzz "local.com/buzz"
	"github.com/golang/snappy" // this is a "typical" import
)

var _, _, _, _, _ = context.Background, bar.B, baz.B, buzz.B, snappy.ErrCorrupt
`,
		out: `package main

import (
	"context"

	"github.com/golang/snappy" // this is a "typical" import

	bar "local.com/bar"
	baz "local.com/baz"
	buzz "local.com/buzz"
)

var _, _, _, _, _ = context.Background, bar.B, baz.B, buzz.B, snappy.ErrCorrupt
`,
	},

	// Non-idempotent comment formatting
	// golang.org/issue/8035
	{
		name: "comments_formatted",
		in: `package main

import (
	"fmt"                     // A
	"go/ast"                  // B
	_ "manypackages.com/packagec"    // C
)

func main() { _, _ = fmt.Print, ast.Walk }
`,
		out: `package main

import (
	"fmt"    // A
	"go/ast" // B

	_ "manypackages.com/packagec" // C
)

func main() { _, _ = fmt.Print, ast.Walk }
`,
	},

	// Failure to delete all duplicate imports
	// golang.org/issue/8459
	{
		name: "remove_duplicates",
		in: `package main

import (
	"fmt"
	"log"
	"log"
	"math"
)

func main() { fmt.Println("pi:", math.Pi) }
`,
		out: `package main

import (
	"fmt"
	"math"
)

func main() { fmt.Println("pi:", math.Pi) }
`,
	},

	// Too aggressive prefix matching
	// golang.org/issue/9961
	{
		name: "no_extra_groups",
		in: `package p

import (
	"zip"

	"rsc.io/p"
)

var (
	_ = fmt.Print
	_ = zip.Store
	_ p.P
	_ = regexp.Compile
)
`,
		out: `package p

import (
	"fmt"
	"regexp"
	"zip"

	"rsc.io/p"
)

var (
	_ = fmt.Print
	_ = zip.Store
	_ p.P
	_ = regexp.Compile
)
`,
	},

	// Unused named import is mistaken for unnamed import
	// golang.org/issue/8149
	{
		name: "named_import_doesnt_provide_package_name",
		in: `package main

import foo "fmt"

func main() { fmt.Println() }
`,
		out: `package main

import "fmt"

func main() { fmt.Println() }
`,
	},

	// Unused named import is mistaken for unnamed import
	// golang.org/issue/8149
	{
		name: "unused_named_import_removed",
		in: `package main

import (
	"fmt"
	x "fmt"
)

func main() { fmt.Println() }
`,
		out: `package main

import (
	"fmt"
)

func main() { fmt.Println() }
`,
	},

	{
		name: "ignore_unexported_identifier",
		in: `package main
var _ = fmt.unexported`,
		out: `package main

var _ = fmt.unexported
`,
	},

	// FormatOnly
	{
		name:       "formatonly_works",
		formatOnly: true,
		in: `package main

import (
"fmt"
"manypackages.com/packagea"
)

func main() {}
`,
		out: `package main

import (
	"fmt"

	"manypackages.com/packagea"
)

func main() {}
`,
	},

	{
		name: "preserve_import_group",
		in: `package p

import (
	"bytes"
	"fmt"
)

var _ = fmt.Sprintf
`,
		out: `package p

import (
	"fmt"
)

var _ = fmt.Sprintf
`,
	},
	{
		name: "import_grouping_not_path_dependent_no_groups",
		in: `package main

import (
	"time"
)

func main() {
	_ = snappy.ErrCorrupt
	_ = p.P
	_ = time.Parse
}
`,
		out: `package main

import (
	"time"

	"github.com/golang/snappy"
	"rsc.io/p"
)

func main() {
	_ = snappy.ErrCorrupt
	_ = p.P
	_ = time.Parse
}
`,
	},

	{
		name: "import_grouping_not_path_dependent_existing_group",
		in: `package main

import (
	"time"

	"github.com/golang/snappy"
)

func main() {
	_ = snappy.ErrCorrupt
	_ = p.P
	_ = time.Parse
}
`,
		out: `package main

import (
	"time"

	"github.com/golang/snappy"
	"rsc.io/p"
)

func main() {
	_ = snappy.ErrCorrupt
	_ = p.P
	_ = time.Parse
}
`,
	},

	// golang.org/issue/12097
	{
		name: "package_statement_insertion_preserves_comments",
		in: `// a
// b
// c

func main() {
    _ = fmt.Println
}`,
		out: `package main

import "fmt"

// a
// b
// c

func main() {
	_ = fmt.Println
}
`,
	},

	{
		name: "import_comment_stays_on_import",
		in: `package main

import (
	"math" // fun
)

func main() {
	x := math.MaxInt64
	fmt.Println(strings.Join(",", []string{"hi"}), x)
}`,
		out: `package main

import (
	"fmt"
	"math" // fun
	"strings"
)

func main() {
	x := math.MaxInt64
	fmt.Println(strings.Join(",", []string{"hi"}), x)
}
`,
	},

	{
		name: "no_blank_after_comment",
		in: `package main

import (
	_ "io"
	_ "net/http"
	_ "net/http/pprof" // install the pprof http handlers
	_ "strings"
)

func main() {
}
`,
		out: `package main

import (
	_ "io"
	_ "net/http"
	_ "net/http/pprof" // install the pprof http handlers
	_ "strings"
)

func main() {
}
`,
	},

	{
		name: "no_blank_after_comment_reordered",
		in: `package main

import (
	_ "io"
	_ "net/http/pprof" // install the pprof http handlers
	_ "net/http"
	_ "strings"
)

func main() {
}
`,
		out: `package main

import (
	_ "io"
	_ "net/http"
	_ "net/http/pprof" // install the pprof http handlers
	_ "strings"
)

func main() {
}
`,
	},

	{
		name: "no_blank_after_comment_unnamed",
		in: `package main

import (
	"encoding/json"
	"io"
	"net/http"
	_ "net/http/pprof" // install the pprof http handlers
	"strings"

	"manypackages.com/packagea"
)

func main() {
	_ = strings.ToUpper("hello")
	_ = io.EOF
	var (
		_ json.Number
		_ *http.Request
		_ packagea.A
	)
}
`,
		out: `package main

import (
	"encoding/json"
	"io"
	"net/http"
	_ "net/http/pprof" // install the pprof http handlers
	"strings"

	"manypackages.com/packagea"
)

func main() {
	_ = strings.ToUpper("hello")
	_ = io.EOF
	var (
		_ json.Number
		_ *http.Request
		_ packagea.A
	)
}
`,
	},

	{
		name: "blank_after_package_statement_with_comment",
		in: `package p // comment

import "math"

var _ = fmt.Printf
`,
		out: `package p // comment

import "fmt"

var _ = fmt.Printf
`,
	},

	{
		name: "blank_after_package_statement_no_comment",
		in: `package p

import "math"

var _ = fmt.Printf
`,
		out: `package p

import "fmt"

var _ = fmt.Printf
`,
	},

	{
		name: "cryptorand_preferred_easy_possible",
		in: `package p

var _ = rand.Read
`,
		out: `package p

import "crypto/rand"

var _ = rand.Read
`,
	},

	{
		name: "cryptorand_preferred_easy_impossible",
		in: `package p

var _ = rand.NewZipf
`,
		out: `package p

import "math/rand/v2"

var _ = rand.NewZipf
`,
	},

	{
		name: "cryptorand_preferred_complex_possible",
		in: `package p

var _, _ = rand.Read, rand.Prime
`,
		out: `package p

import "crypto/rand"

var _, _ = rand.Read, rand.Prime
`,
	},

	{
		name: "cryptorand_preferred_complex_impossible",
		in: `package p

var _, _ = rand.Read, rand.NewZipf
`,
		out: `package p

import "math/rand"

var _, _ = rand.Read, rand.NewZipf
`,
	},
	{
		name: "unused_duplicate_imports_remove",
		in: `package main

import (
	"errors"

	"github.com/pkg/errors"
)
`,
		out: `package main
`,
	},
}

func TestSimpleCases(t *testing.T) {
	const localPrefix = "local.com,github.com/local"
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			testConfig{
				modules: []packagestest.Module{
					{
						Name:  "golang.org/fake",
						Files: fm{"x.go": tt.in},
					},
					// Skeleton non-stdlib packages for use during testing.
					// Each includes one arbitrary symbol, e.g. the first declaration in the first file.
					// Try not to add more without a good reason.
					// DO NOT USE PACKAGES NOT LISTED HERE -- they will be downloaded!
					{
						Name:  "rsc.io",
						Files: fm{"p/x.go": "package p\nfunc P(){}\n"},
					},
					{
						Name:  "github.com/golang/snappy",
						Files: fm{"x.go": "package snappy\nvar ErrCorrupt error\n"},
					},
					{
						Name: "manypackages.com",
						Files: fm{
							"packagea/x.go": "package packagea\nfunc A(){}\n",
							"packageb/x.go": "package packageb\nfunc B(){}\n",
							"packagec/x.go": "package packagec\nfunc C(){}\n",
							"packaged/x.go": "package packaged\nfunc D(){}\n",
						},
					},
					{
						Name:  "local.com",
						Files: fm{"foo/x.go": "package foo\nfunc Foo(){}\n"},
					},
					{
						Name:  "github.com/local",
						Files: fm{"bar/x.go": "package bar\nfunc Bar(){}\n"},
					},
				},
			}.test(t, func(t *goimportTest) {
				options := &Options{
					LocalPrefix: localPrefix,
					TabWidth:    8,
					TabIndent:   true,
					Comments:    true,
					Fragment:    true,
					FormatOnly:  tt.formatOnly,
				}
				t.assertProcessEquals("golang.org/fake", "x.go", nil, options, tt.out)
			})

		})
	}
}

func TestAppengine(t *testing.T) {
	const input = `package p

var _, _, _ = fmt.Printf, appengine.Main, datastore.ErrInvalidEntityType
`

	const want = `package p

import (
	"fmt"

	"appengine"
	"appengine/datastore"
)

var _, _, _ = fmt.Printf, appengine.Main, datastore.ErrInvalidEntityType
`

	testConfig{
		gopathOnly: true, // can't create a module named appengine, so no module tests.
		modules: []packagestest.Module{
			{
				Name:  "golang.org/fake",
				Files: fm{"x.go": input},
			},
			{
				Name: "appengine",
				Files: fm{
					"x.go":           "package appengine\nfunc Main(){}\n",
					"datastore/x.go": "package datastore\nvar ErrInvalidEntityType error\n",
				},
			},
		},
	}.processTest(t, "golang.org/fake", "x.go", nil, nil, want)
}

func TestReadFromFilesystem(t *testing.T) {
	tests := []struct {
		name    string
		in, out string
	}{
		{
			name: "works",
			in: `package foo
func bar() {
fmt.Println("hi")
}
`,
			out: `package foo

import "fmt"

func bar() {
	fmt.Println("hi")
}
`,
		},
		{
			name: "missing_package",
			in: `
func bar() {
fmt.Println("hi")
}
`,
			out: `
import "fmt"

func bar() {
	fmt.Println("hi")
}
`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			options := &Options{
				TabWidth:  8,
				TabIndent: true,
				Comments:  true,
				Fragment:  true,
			}
			testConfig{
				module: packagestest.Module{
					Name:  "golang.org/fake",
					Files: fm{"x.go": tt.in},
				},
			}.processTest(t, "golang.org/fake", "x.go", nil, options, tt.out)
		})
	}

}

// Test support for packages in GOPATH that are actually symlinks.
// Also test that a symlink loop does not block the process.
func TestImportSymlinks(t *testing.T) {
	const input = `package p

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`
	const want = `package p

import (
	"fmt"

	"golang.org/fake/x/y/mypkg"
)

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`

	testConfig{
		module: packagestest.Module{
			Name: "golang.org/fake",
			Files: fm{
				"target/f.go":                "package mypkg\nvar Foo = 123\n",
				"x/y/mypkg":                  packagestest.Symlink("../../target"), // valid symlink
				"x/y/apkg":                   packagestest.Symlink(".."),           // symlink loop
				"myotherpackage/toformat.go": input,
			},
		},
	}.processTest(t, "golang.org/fake", "myotherpackage/toformat.go", nil, nil, want)
}

// Test support for packages in GOPATH whose files are symlinks.
func TestImportSymlinkFiles(t *testing.T) {
	const input = `package p

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`
	const want = `package p

import (
	"fmt"

	"golang.org/fake/x/y/mypkg"
)

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`

	testConfig{
		module: packagestest.Module{
			Name: "golang.org/fake",
			Files: fm{
				"target/f.go":                "package mypkg\nvar Foo = 123\n",
				"x/y/mypkg/f.go":             packagestest.Symlink("../../../target/f.go"),
				"myotherpackage/toformat.go": input,
			},
		},
	}.processTest(t, "golang.org/fake", "myotherpackage/toformat.go", nil, nil, want)
}

func TestImportSymlinksWithIgnore(t *testing.T) {
	const input = `package p

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`
	const want = `package p

import "fmt"

var (
	_ = fmt.Print
	_ = mypkg.Foo
)
`

	testConfig{
		gopathOnly: true,
		module: packagestest.Module{
			Name: "golang.org/fake",
			Files: fm{
				"target/f.go":            "package mypkg\nvar Foo = 123\n",
				"x/y/mypkg":              packagestest.Symlink("../../target"), // valid symlink
				"x/y/apkg":               packagestest.Symlink(".."),           // symlink loop
				"myotherpkg/toformat.go": input,
				"../../.goimportsignore": "golang.org/fake/x/y/mypkg\n" +
					"golang.org/fake/x/y/apkg\n",
			},
		},
	}.processTest(t, "golang.org/fake", "myotherpkg/toformat.go", nil, nil, want)
}

// Test for x/y/v2 convention for package y.
func TestModuleVersion(t *testing.T) {
	const input = `package p

import (
	"fmt"

	"github.com/foo/v2"
)

var (
	_ = fmt.Print
	_ = foo.Foo
)
`

	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "mypkg.com/outpkg",
				Files: fm{"toformat.go": input},
			},
			{
				Name:  "github.com/foo/v2",
				Files: fm{"x.go": "package foo\n func Foo(){}\n"},
			},
		},
	}.processTest(t, "mypkg.com/outpkg", "toformat.go", nil, nil, input)
}

// Test for correctly identifying the name of a vendored package when it
// differs from its directory name. In this test, the import line
// "mypkg.com/mypkg_v1" would be removed if goimports wasn't able to detect
// that the package name is "mypkg".
func TestVendorPackage(t *testing.T) {
	const input = `package p
import (
	"fmt"
	"mypkg.com/mypkg_v1"
)
var _, _ = fmt.Print, mypkg.Foo
`

	const want = `package p

import (
	"fmt"

	mypkg "mypkg.com/mypkg_v1"
)

var _, _ = fmt.Print, mypkg.Foo
`

	testConfig{
		gopathOnly: true,
		module: packagestest.Module{
			Name: "mypkg.com/outpkg",
			Files: fm{
				"vendor/mypkg.com/mypkg_v1/f.go": "package mypkg\nvar Foo = 123\n",
				"toformat.go":                    input,
			},
		},
	}.processTest(t, "mypkg.com/outpkg", "toformat.go", nil, nil, want)
}

func TestInternal(t *testing.T) {
	const input = `package bar

var _ = race.Acquire
`
	const importAdded = `package bar

import "foo.com/internal/race"

var _ = race.Acquire
`

	// Packages under the same directory should be able to use internal packages.
	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"internal/race/x.go": "package race\n func Acquire(){}\n",
				"bar/x.go":           input,
			},
		},
	}.processTest(t, "foo.com", "bar/x.go", nil, nil, importAdded)

	// Packages outside the same directory should not.
	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "foo.com",
				Files: fm{"internal/race/x.go": "package race\n func Acquire(){}\n"},
			},
			{
				Name:  "bar.com",
				Files: fm{"x.go": input},
			},
		},
	}.processTest(t, "bar.com", "x.go", nil, nil, input)
}

func TestProcessVendor(t *testing.T) {
	const input = `package p

var _ = hpack.HuffmanDecode
`
	const want = `package p

import "golang.org/x/net/http2/hpack"

var _ = hpack.HuffmanDecode
`
	testConfig{
		gopathOnly: true,
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"vendor/golang.org/x/net/http2/hpack/huffman.go": "package hpack\nfunc HuffmanDecode() { }\n",
				"bar/x.go": input,
			},
		},
	}.processTest(t, "foo.com", "bar/x.go", nil, nil, want)
}

func TestFindStdlib(t *testing.T) {
	tests := []struct {
		pkg     string
		symbols []string
		want    string
	}{
		{"http", []string{"Get"}, "net/http"},
		{"http", []string{"Get", "Post"}, "net/http"},
		{"http", []string{"Get", "Foo"}, ""},
		{"bytes", []string{"Buffer"}, "bytes"},
		{"ioutil", []string{"Discard"}, "io/ioutil"},
	}
	for _, tt := range tests {
		input := "package p\n"
		for _, sym := range tt.symbols {
			input += fmt.Sprintf("var _ = %s.%s\n", tt.pkg, sym)
		}
		testConfig{
			module: packagestest.Module{
				Name:  "foo.com",
				Files: fm{"x.go": input},
			},
		}.test(t, func(t *goimportTest) {
			buf, err := t.process("foo.com", "x.go", nil, nil)
			if err != nil {
				t.Fatal(err)
			}
			if got := string(buf); !strings.Contains(got, tt.want) {
				t.Errorf("Process(%q) = %q, wanted it to contain %q", input, buf, tt.want)
			}
		})
	}
}

// https://golang.org/issue/31814
func TestStdlibNotPrefixed(t *testing.T) {
	const input = `package p
var _ = bytes.Buffer
`
	const want = `package p

import "bytes"

var _ = bytes.Buffer
`
	// Force a scan of the stdlib.
	savedStdlib := stdlib.PackageSymbols
	defer func() { stdlib.PackageSymbols = savedStdlib }()
	stdlib.PackageSymbols = nil

	testConfig{
		module: packagestest.Module{
			Name:  "ignored.com",
			Files: fm{"x.go": "package x"},
		},
	}.test(t, func(t *goimportTest) {
		// Run in GOROOT/src so that the std module shows up in go list -m all.
		t.env.WorkingDir = filepath.Join(t.goroot, "src")
		got, err := t.processNonModule(filepath.Join(t.goroot, "src/x.go"), []byte(input), nil)
		if err != nil {
			t.Fatalf("Process() = %v", err)
		}
		if string(got) != want {
			t.Errorf("Got:\n%s\nWant:\n%s", got, want)
		}
	})
}

func TestStdlibSelfImports(t *testing.T) {
	const input = `package rc4

var _ = rc4.NewCipher
`

	testConfig{
		module: packagestest.Module{
			Name:  "ignored.com",
			Files: fm{"x.go": "package x"},
		},
	}.test(t, func(t *goimportTest) {
		got, err := t.processNonModule(filepath.Join(t.goroot, "src/crypto/rc4/foo.go"), []byte(input), nil)
		if err != nil {
			t.Fatalf("Process() = %v", err)
		}
		if string(got) != input {
			t.Errorf("Got:\n%s\nWant:\n%s", got, input)
		}
	})
}

type testConfig struct {
	gopathOnly bool
	module     packagestest.Module
	modules    []packagestest.Module
}

// fm is the type for a packagestest.Module's Files, abbreviated for shorter lines.
type fm map[string]any

func (c testConfig) test(t *testing.T, fn func(*goimportTest)) {
	t.Helper()

	if c.module.Name != "" {
		c.modules = []packagestest.Module{c.module}
	}

	for _, exporter := range packagestest.All {
		t.Run(exporter.Name(), func(t *testing.T) {
			t.Helper()
			if c.gopathOnly && exporter.Name() == "Modules" {
				t.Skip("test marked GOPATH-only")
			}
			exported := packagestest.Export(t, exporter, c.modules)
			defer exported.Cleanup()

			env := map[string]string{}
			for _, kv := range exported.Config.Env {
				split := strings.SplitN(kv, "=", 2)
				env[split[0]] = split[1]
			}
			it := &goimportTest{
				T: t,
				env: &ProcessEnv{
					Env:         env,
					WorkingDir:  exported.Config.Dir,
					GocmdRunner: &gocommand.Runner{},
				},
				exported: exported,
			}
			if *testDebug {
				it.env.Logf = log.Printf
			}
			// packagestest clears out GOROOT to work around golang/go#32849,
			// which isn't relevant here. Fill it back in so we can find the standard library.
			it.env.Env["GOROOT"] = build.Default.GOROOT
			it.goroot = build.Default.GOROOT

			fn(it)
		})
	}
}

func (c testConfig) processTest(t *testing.T, module, file string, contents []byte, opts *Options, want string) {
	t.Helper()
	c.test(t, func(t *goimportTest) {
		t.Helper()
		t.assertProcessEquals(module, file, contents, opts, want)
	})
}

type goimportTest struct {
	*testing.T
	goroot   string
	env      *ProcessEnv
	exported *packagestest.Exported
}

func (t *goimportTest) process(module, file string, contents []byte, opts *Options) ([]byte, error) {
	t.Helper()
	f := t.exported.File(module, file)
	if f == "" {
		t.Fatalf("%v not found in exported files (typo in filename?)", file)
	}
	return t.processNonModule(f, contents, opts)
}

func (t *goimportTest) processNonModule(file string, contents []byte, opts *Options) ([]byte, error) {
	if contents == nil {
		var err error
		contents, err = os.ReadFile(file)
		if err != nil {
			return nil, err
		}
	}
	if opts == nil {
		opts = &Options{Comments: true, TabIndent: true, TabWidth: 8}
	}
	// ProcessEnv is not safe for concurrent use. Make a copy.
	opts.Env = t.env.CopyConfig()
	return Process(file, contents, opts)
}

func (t *goimportTest) assertProcessEquals(module, file string, contents []byte, opts *Options, want string) {
	buf, err := t.process(module, file, contents, opts)
	if err != nil {
		t.Fatalf("Process() = %v", err)
	}
	if string(buf) != want {
		t.Errorf("Got:\n'%s'\nWant:\n'%s'", buf, want) // 's show empty lines
	}
}

// Tests that added imports are renamed when the import path's base doesn't
// match its package name.
func TestRenameWhenPackageNameMismatch(t *testing.T) {
	const input = `package main
 const Y = bar.X`

	const want = `package main

import bar "foo.com/foo/bar/baz"

const Y = bar.X
`
	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"foo/bar/baz/x.go": "package bar \n const X = 1",
				"test/t.go":        input,
			},
		},
	}.processTest(t, "foo.com", "test/t.go", nil, nil, want)
}

func TestPanicAstutils(t *testing.T) {
	t.Skip("panic in ast/astutil/imports.go, should be PostionFor(,false) at lines 273, 274, at least")
	const input = `package main
//line mah.go:600

import (
"foo.com/a.thing"
"foo.com/surprise"
"foo.com/v1"
"foo.com/other/v2"
"foo.com/other/v3"
)
`

	const want = `package main

//line mah.go:600

import (
	"foo.com/a.thing"
	"foo.com/go-thing"
	gow "foo.com/go-wrong"
	v2 "foo.com/other/v2"
	"foo.com/other/v3"
	bar "foo.com/surprise"
	v1 "foo.com/v1"
)

`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"test/t.go": input,
			},
		},
	}.processTest(t, "foo.com", "test/t.go", nil, nil, want)
}

// without PositionFor in sortImports this test panics
func TestPanic51916(t *testing.T) {
	const input = `package main
//line mah.go:600

import (
"foo.com/a.thing"
"foo.com/surprise"
"foo.com/v1"
"foo.com/other/v2"
"foo.com/other/v3"
"foo.com/go-thing"
"foo.com/go-wrong"
)

var _ = []interface{}{bar.X, v1.Y, a.A, v2.V2, other.V3, thing.Thing, gow.Wrong}`

	const want = `package main

//line mah.go:600

import (
	"foo.com/a.thing"
	"foo.com/go-thing"
	gow "foo.com/go-wrong"
	v2 "foo.com/other/v2"
	"foo.com/other/v3"
	bar "foo.com/surprise"
	v1 "foo.com/v1"
)

var _ = []interface{}{bar.X, v1.Y, a.A, v2.V2, other.V3, thing.Thing, gow.Wrong}
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"a.thing/a.go":  "package a \n const A = 1",
				"surprise/x.go": "package bar \n const X = 1",
				"v1/x.go":       "package v1 \n const Y = 1",
				"other/v2/y.go": "package v2 \n const V2 = 1",
				"other/v3/z.go": "package other \n const V3 = 1",
				"go-thing/b.go": "package thing \n const Thing = 1",
				"go-wrong/b.go": "package gow \n const Wrong = 1",
				"test/t.go":     input,
			},
		},
	}.processTest(t, "foo.com", "test/t.go", nil, nil, want)
}

// Tests that an existing import with badly mismatched path/name has its name
// correctly added. See #28645 and #29041.
// and check that //line directives are ignored (#51916)
func TestAddNameToMismatchedImport(t *testing.T) {
	const input = `package main

import (
"foo.com/a.thing"
"foo.com/surprise"
"foo.com/v1"
"foo.com/other/v2"
"foo.com/other/v3"
"foo.com/go-thing"
"foo.com/go-wrong"
)

var _ = []interface{}{bar.X, v1.Y, a.A, v2.V2, other.V3, thing.Thing, gow.Wrong}`

	const want = `package main

import (
	"foo.com/a.thing"
	"foo.com/go-thing"
	gow "foo.com/go-wrong"
	v2 "foo.com/other/v2"
	"foo.com/other/v3"
	bar "foo.com/surprise"
	v1 "foo.com/v1"
)

var _ = []interface{}{bar.X, v1.Y, a.A, v2.V2, other.V3, thing.Thing, gow.Wrong}
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"a.thing/a.go":  "package a \n const A = 1",
				"surprise/x.go": "package bar \n const X = 1",
				"v1/x.go":       "package v1 \n const Y = 1",
				"other/v2/y.go": "package v2 \n const V2 = 1",
				"other/v3/z.go": "package other \n const V3 = 1",
				"go-thing/b.go": "package thing \n const Thing = 1",
				"go-wrong/b.go": "package gow \n const Wrong = 1",
				"test/t.go":     input,
			},
		},
	}.processTest(t, "foo.com", "test/t.go", nil, nil, want)
}

// Tests that the LocalPrefix option causes imports
// to be added into a later group (num=3).
func TestLocalPrefix(t *testing.T) {
	tests := []struct {
		name        string
		modules     []packagestest.Module
		localPrefix string
		src         string
		want        string
	}{
		{
			name: "one_local",
			modules: []packagestest.Module{
				{
					Name: "foo.com",
					Files: fm{
						"bar/bar.go": "package bar \n const X = 1",
					},
				},
			},
			localPrefix: "foo.com/",
			src:         "package main \n const Y = bar.X \n const _ = runtime.GOOS",
			want: `package main

import (
	"runtime"

	"foo.com/bar"
)

const Y = bar.X
const _ = runtime.GOOS
`,
		},
		{
			name: "two_local",
			modules: []packagestest.Module{
				{
					Name: "foo.com",
					Files: fm{
						"foo/foo.go":     "package foo \n const X = 1",
						"foo/bar/bar.go": "package bar \n const X = 1",
					},
				},
			},
			localPrefix: "foo.com/foo",
			src:         "package main \n const Y = bar.X \n const Z = foo.X \n const _ = runtime.GOOS",
			want: `package main

import (
	"runtime"

	"foo.com/foo"
	"foo.com/foo/bar"
)

const Y = bar.X
const Z = foo.X
const _ = runtime.GOOS
`,
		},
		{
			name: "three_prefixes",
			modules: []packagestest.Module{
				{
					Name:  "example.org/pkg",
					Files: fm{"pkg.go": "package pkg \n const A = 1"},
				},
				{
					Name:  "foo.com",
					Files: fm{"bar/bar.go": "package bar \n const B = 1"},
				},
				{
					Name:  "code.org/r/p",
					Files: fm{"expproj/expproj.go": "package expproj \n const C = 1"},
				},
			},
			localPrefix: "example.org/pkg,foo.com/,code.org",
			src:         "package main \n const X = pkg.A \n const Y = bar.B \n const Z = expproj.C \n const _ = runtime.GOOS",
			want: `package main

import (
	"runtime"

	"code.org/r/p/expproj"
	"example.org/pkg"
	"foo.com/bar"
)

const X = pkg.A
const Y = bar.B
const Z = expproj.C
const _ = runtime.GOOS
`,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			testConfig{
				// The module being processed has to be first so it's the primary module.
				modules: append([]packagestest.Module{{
					Name:  "test.com",
					Files: fm{"t.go": tt.src},
				}}, tt.modules...),
			}.test(t, func(t *goimportTest) {
				options := &Options{
					LocalPrefix: tt.localPrefix,
					TabWidth:    8,
					TabIndent:   true,
					Comments:    true,
					Fragment:    true,
				}
				t.assertProcessEquals("test.com", "t.go", nil, options, tt.want)
			})
		})
	}
}

// Tests that "package documentation" files are ignored.
func TestIgnoreDocumentationPackage(t *testing.T) {
	const input = `package x

const Y = foo.X
`
	const want = `package x

import "foo.com/foo"

const Y = foo.X
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"foo/foo.go": "package foo\nconst X = 1\n",
				"foo/doc.go": "package documentation \n // just to confuse things\n",
				"x/x.go":     input,
			},
		},
	}.processTest(t, "foo.com", "x/x.go", nil, nil, want)
}

// Tests importPathToNameGoPathParse and in particular that it stops
// after finding the first non-documentation package name, not
// reporting an error on inconsistent package names (since it should
// never make it that far).
func TestImportPathToNameGoPathParse(t *testing.T) {
	testConfig{
		module: packagestest.Module{
			Name: "example.net/pkg",
			Files: fm{
				"doc.go": "package documentation\n", // ignored
				"gen.go": "package main\n",          // also ignored
				"pkg.go": "package the_pkg_name_to_find\n  and this syntax error is ignored because of parser.PackageClauseOnly",
				"z.go":   "package inconsistent\n", // inconsistent but ignored
			},
		},
	}.test(t, func(t *goimportTest) {
		if strings.Contains(t.Name(), "GoPackages") {
			t.Skip("go/packages does not ignore package main")
		}
		r, err := t.env.GetResolver()
		if err != nil {
			t.Fatal(err)
		}
		srcDir := filepath.Dir(t.exported.File("example.net/pkg", "z.go"))
		names, err := r.loadPackageNames([]string{"example.net/pkg"}, srcDir)
		if err != nil {
			t.Fatal(err)
		}
		const want = "the_pkg_name_to_find"
		if got := names["example.net/pkg"]; got != want {
			t.Errorf("loadPackageNames(..) = %q; want %q", got, want)
		}
	})
}

func TestIgnoreConfiguration(t *testing.T) {
	const input = `package x

const _ = pkg.X
`
	const want = `package x

import "foo.com/otherwise-longer-so-worse-example/foo/pkg"

const _ = pkg.X
`

	testConfig{
		gopathOnly: true,
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"../.goimportsignore":                              "# comment line\n\n foo.com/example", // tests comment, blank line, whitespace trimming
				"example/pkg/pkg.go":                               "package pkg\nconst X = 1",
				"otherwise-longer-so-worse-example/foo/pkg/pkg.go": "package pkg\nconst X = 1",
				"x/x.go": input,
			},
		},
	}.processTest(t, "foo.com", "x/x.go", nil, nil, want)
}

// Skip "node_modules" directory.
func TestSkipNodeModules(t *testing.T) {
	const input = `package x

const _ = pkg.X
`
	const want = `package x

import "foo.com/otherwise-longer/not_modules/pkg"

const _ = pkg.X
`

	testConfig{
		gopathOnly: true,
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"example/node_modules/pkg/a.go":         "package pkg\nconst X = 1",
				"otherwise-longer/not_modules/pkg/a.go": "package pkg\nconst X = 1",
				"x/x.go":                                input,
			},
		},
	}.processTest(t, "foo.com", "x/x.go", nil, nil, want)
}

// Tests that package global variables with the same name and function name as
// a function in a separate package do not result in an import which masks
// the global variable
func TestGlobalImports(t *testing.T) {
	const usesGlobal = `package pkg

func doSomething() {
	t := time.Now()
}
`

	const declaresGlobal = `package pkg

type Time struct{}

func (t Time) Now() Time {
	return Time{}
}

var time Time
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/uses.go":   usesGlobal,
				"pkg/global.go": declaresGlobal,
			},
		},
	}.processTest(t, "foo.com", "pkg/uses.go", nil, nil, usesGlobal)
}

// Some people put multiple packages' files in the same directory. Globals
// declared in other packages should be ignored.
func TestGlobalImports_DifferentPackage(t *testing.T) {
	const declaresGlobal = `package main
var fmt int
`
	const input = `package pkg
var _ = fmt.Printf
`
	const want = `package pkg

import "fmt"

var _ = fmt.Printf
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/main.go": declaresGlobal,
				"pkg/uses.go": input,
			},
		},
	}.processTest(t, "foo.com", "pkg/uses.go", nil, nil, want)
}

func TestGlobalImports_MultipleMains(t *testing.T) {
	const declaresGlobal = `package main
var fmt int
`
	const input = `package main
import "fmt"
var _, _ = fmt.Printf, bytes.Equal
`
	const want = `package main

import (
	"bytes"
	"fmt"
)

var _, _ = fmt.Printf, bytes.Equal
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/main.go": declaresGlobal,
				"pkg/uses.go": input,
			},
		},
	}.processTest(t, "foo.com", "pkg/uses.go", nil, nil, want)
}

// Tests that sibling files - other files in the same package - can provide an
// import that may not be the default one otherwise.
func TestSiblingImports(t *testing.T) {

	// provide is the sibling file that provides the desired import.
	const provide = `package siblingimporttest

import "local/log"
import "my/bytes"
import renamed "fmt"

func LogSomething() {
	log.Print("Something")
	bytes.SomeFunc()
	renamed.Println("Something")
}
`

	// need is the file being tested that needs the import.
	const need = `package siblingimporttest

var _ = bytes.Buffer{}

func LogSomethingElse() {
	log.Print("Something else")
	renamed.Println("Yet another")
}
`

	// want is the expected result file
	const want = `package siblingimporttest

import (
	"bytes"
	renamed "fmt"
	"local/log"
)

var _ = bytes.Buffer{}

func LogSomethingElse() {
	log.Print("Something else")
	renamed.Println("Yet another")
}
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"p/needs_import.go":    need,
				"p/provides_import.go": provide,
			},
		},
	}.processTest(t, "foo.com", "p/needs_import.go", nil, nil, want)
}

// Tests #29180: a sibling import of the right package with the wrong name is used.
func TestSiblingImport_Misnamed(t *testing.T) {
	const sibling = `package main
import renamed "fmt"
var _ = renamed.Printf
`
	const input = `package pkg
var _ = fmt.Printf
`
	const want = `package pkg

import "fmt"

var _ = fmt.Printf
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/main.go": sibling,
				"pkg/uses.go": input,
			},
		},
	}.processTest(t, "foo.com", "pkg/uses.go", nil, nil, want)

}

// Tests that an input file's own package is ignored.
func TestIgnoreOwnPackage(t *testing.T) {
	const input = `package pkg

const _ = pkg.X
`
	const want = `package pkg

const _ = pkg.X
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/a.go": "package pkg\nconst X = 1",
				"pkg/b.go": input,
			},
		},
	}.processTest(t, "foo.com", "pkg/b.go", nil, nil, want)
}

func TestExternalTestImportsPackageUnderTest(t *testing.T) {
	const provide = `package pkg
func DoIt(){}
`
	const input = `package pkg_test

var _ = pkg.DoIt`

	const want = `package pkg_test

import "foo.com/pkg"

var _ = pkg.DoIt
`

	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"pkg/provide.go": provide,
				"pkg/x_test.go":  input,
			},
		},
	}.processTest(t, "foo.com", "pkg/x_test.go", nil, nil, want)
}

func TestPkgIsCandidate(t *testing.T) {
	tests := []struct {
		name     string
		filename string
		pkgIdent string
		pkg      *pkg
		want     bool
	}{
		{
			name:     "normal_match",
			filename: "/gopath/src/my/pkg/pkg.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/client",
				importPathShort: "client",
			},
			want: true,
		},
		{
			name:     "no_match",
			filename: "/gopath/src/my/pkg/pkg.go",
			pkgIdent: "zzz",
			pkg: &pkg{
				dir:             "/gopath/src/client",
				importPathShort: "client",
			},
			want: false,
		},
		{
			name:     "match_too_early",
			filename: "/gopath/src/my/pkg/pkg.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/client/foo/foo/foo",
				importPathShort: "client/foo/foo",
			},
			want: false,
		},
		{
			name:     "substring_match",
			filename: "/gopath/src/my/pkg/pkg.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/foo/go-client",
				importPathShort: "foo/go-client",
			},
			want: true,
		},
		{
			name:     "hidden_internal",
			filename: "/gopath/src/my/pkg/pkg.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/foo/internal/client",
				importPathShort: "foo/internal/client",
			},
			want: false,
		},
		{
			name:     "visible_internal",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/foo/internal/client",
				importPathShort: "foo/internal/client",
			},
			want: true,
		},
		{
			name:     "invisible_vendor",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/other/vendor/client",
				importPathShort: "client",
			},
			want: false,
		},
		{
			name:     "visible_vendor",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "client",
			pkg: &pkg{
				dir:             "/gopath/src/foo/vendor/client",
				importPathShort: "client",
			},
			want: true,
		},
		{
			name:     "match_with_hyphens",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "socketio",
			pkg: &pkg{
				dir:             "/gopath/src/foo/socket-io",
				importPathShort: "foo/socket-io",
			},
			want: true,
		},
		{
			name:     "match_with_mixed_case",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "fooprod",
			pkg: &pkg{
				dir:             "/gopath/src/foo/FooPROD",
				importPathShort: "foo/FooPROD",
			},
			want: true,
		},
		{
			name:     "matches_with_hyphen_and_caps",
			filename: "/gopath/src/foo/bar.go",
			pkgIdent: "fooprod",
			pkg: &pkg{
				dir:             "/gopath/src/foo/Foo-PROD",
				importPathShort: "foo/Foo-PROD",
			},
			want: true,
		},
	}
	for i, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			refs := References{tt.pkgIdent: nil}
			got := pkgIsCandidate(tt.filename, refs, tt.pkg)
			if got != tt.want {
				t.Errorf("test %d. pkgIsCandidate(%q, %q, %+v) = %v; want %v",
					i, tt.filename, tt.pkgIdent, *tt.pkg, got, tt.want)
			}
		})
	}
}

// Issue 20941: this used to panic on Windows.
func TestProcessStdin(t *testing.T) {
	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
		},
	}.test(t, func(t *goimportTest) {
		got, err := t.processNonModule("<standard input>", []byte("package main\nfunc main() {\n\tfmt.Println(123)\n}\n"), nil)
		if err != nil {
			t.Fatal(err)
		}
		if !strings.Contains(string(got), `"fmt"`) {
			t.Errorf("expected fmt import; got: %s", got)
		}
	})
}

// Tests LocalPackagePromotion when there is a local package that matches, it
// should be the closest match.
// https://golang.org/issues/17557
func TestLocalPackagePromotion(t *testing.T) {
	const input = `package main
var c = &config.SystemConfig{}
`
	const want = `package main

import "mycompany.net/tool/config"

var c = &config.SystemConfig{}
`

	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "config.net/config",
				Files: fm{"config.go": "package config\n type SystemConfig struct {}"}, // Will match but should not be first choice
			},
			{
				Name:  "mycompany.net/config",
				Files: fm{"config.go": "package config\n type SystemConfig struct {}"}, // Will match but should not be first choice
			},
			{
				Name: "mycompany.net/tool",
				Files: fm{
					"config/config.go": "package config\n type SystemConfig struct {}", // Local package should be promoted over shorter package
					"main.go":          input,
				},
			},
		},
	}.processTest(t, "mycompany.net/tool", "main.go", nil, nil, want)
}

// Tests FindImportInLocalGoFiles looks at the import lines for other Go files in the
// local directory, since the user is likely to import the same packages in the current
// Go file.  If an import is found that satisfies the need, it should be used over the
// standard library.
// https://golang.org/issues/17557
func TestFindImportInLocalGoFiles(t *testing.T) {
	const input = `package main
 var _ = &bytes.Buffer{}`

	const want = `package main

import "bytes.net/bytes"

var _ = &bytes.Buffer{}
`
	testConfig{
		modules: []packagestest.Module{
			{
				Name: "mycompany.net/tool",
				Files: fm{
					"io.go":   "package main\n import \"bytes.net/bytes\"\n var _ = &bytes.Buffer{}", // Contains package import that will cause stdlib to be ignored
					"main.go": input,
				},
			},
			{
				Name:  "bytes.net/bytes",
				Files: fm{"bytes.go": "package bytes\n type Buffer struct {}"}, // Should be selected over standard library
			},
		},
	}.processTest(t, "mycompany.net/tool", "main.go", nil, nil, want)
}

func TestInMemoryFile(t *testing.T) {
	const input = `package main
 var _ = &bytes.Buffer{}`

	const want = `package main

import "bytes"

var _ = &bytes.Buffer{}
`
	testConfig{
		module: packagestest.Module{
			Name:  "foo.com",
			Files: fm{"x.go": "package x\n"},
		},
	}.processTest(t, "foo.com", "x.go", []byte(input), nil, want)
}

func TestImportNoGoFiles(t *testing.T) {
	const input = `package main
 var _ = &bytes.Buffer{}`

	const want = `package main

import "bytes"

var _ = &bytes.Buffer{}
`
	testConfig{
		module: packagestest.Module{
			Name: "mycompany.net",
		},
	}.test(t, func(t *goimportTest) {
		buf, err := t.processNonModule("mycompany.net/tool/main.go", []byte(input), nil)
		if err != nil {
			t.Fatalf("Process() = %v", err)
		}
		if string(buf) != want {
			t.Errorf("Got:\n%s\nWant:\n%s", buf, want)
		}
	})

}

// Ensures a token as large as 500000 bytes can be handled
// https://golang.org/issues/18201
func TestProcessLargeToken(t *testing.T) {
	largeString := strings.Repeat("x", 500000)

	input := `package testimports

import (
	"bytes"
)

const s = fmt.Sprintf("%s", "` + largeString + `")
var _ = bytes.Buffer{}

// end
`

	want := `package testimports

import (
	"bytes"
	"fmt"
)

const s = fmt.Sprintf("%s", "` + largeString + `")

var _ = bytes.Buffer{}

// end
`

	testConfig{
		module: packagestest.Module{
			Name:  "foo.com",
			Files: fm{"foo.go": input},
		},
	}.processTest(t, "foo.com", "foo.go", nil, nil, want)
}

// Tests that an external test package will import the package under test if it
// also uses symbols exported only in test files.
// https://golang.org/issues/29979
func TestExternalTest(t *testing.T) {
	const input = `package a_test
func TestX() {
	a.X()
	a.Y()
}
`
	const want = `package a_test

import "foo.com/a"

func TestX() {
	a.X()
	a.Y()
}
`

	testConfig{
		modules: []packagestest.Module{
			{
				Name: "foo.com/a",
				Files: fm{
					"a.go":           "package a\n func X() {}",
					"export_test.go": "package a\n func Y() {}",
					"a_test.go":      input,
				},
			},
		},
	}.processTest(t, "foo.com/a", "a_test.go", nil, nil, want)
}

// TestGetCandidates tests that get packages finds packages
// with correct priorities.
func TestGetCandidates(t *testing.T) {
	type res struct {
		relevance  float64
		name, path string
	}
	want := []res{
		{0, "bytes", "bytes"},
		{0, "http", "net/http"},
		{0, "rand", "crypto/rand"},
		{0, "bar", "bar.com/bar"},
		{0, "foo", "foo.com/foo"},
	}

	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "bar.com",
				Files: fm{"bar/bar.go": "package bar\n"},
			},
			{
				Name:  "foo.com",
				Files: fm{"foo/foo.go": "package foo\n"},
			},
		},
	}.test(t, func(t *goimportTest) {
		var mu sync.Mutex
		var got []res
		add := func(c ImportFix) {
			mu.Lock()
			defer mu.Unlock()
			for _, w := range want {
				if c.StmtInfo.ImportPath == w.path {
					got = append(got, res{c.Relevance, c.IdentName, c.StmtInfo.ImportPath})
				}
			}
		}
		if err := GetAllCandidates(context.Background(), add, "", "x.go", "x", t.env); err != nil {
			t.Fatalf("GetAllCandidates() = %v", err)
		}
		// Sort, then clear out relevance so it doesn't mess up the DeepEqual.
		sort.Slice(got, func(i, j int) bool {
			ri, rj := got[i], got[j]
			if ri.relevance != rj.relevance {
				return ri.relevance > rj.relevance // Highest first.
			}
			return ri.name < rj.name
		})
		for i := range got {
			got[i].relevance = 0
		}
		if !reflect.DeepEqual(want, got) {
			t.Errorf("wanted results in order %v, got %v", want, got)
		}
	})
}

func TestGetImportPaths(t *testing.T) {
	type res struct {
		relevance  float64
		name, path string
	}
	want := []res{
		{0, "http", "net/http"},
		{0, "net", "net"},
		{0, "neta", "neta.com/neta"},
	}

	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "neta.com",
				Files: fm{"neta/neta.go": "package neta\n"},
			},
		},
	}.test(t, func(t *goimportTest) {
		var mu sync.Mutex
		var got []res
		add := func(c ImportFix) {
			mu.Lock()
			defer mu.Unlock()
			for _, w := range want {
				if c.StmtInfo.ImportPath == w.path {
					got = append(got, res{c.Relevance, c.IdentName, c.StmtInfo.ImportPath})
				}
			}
		}
		if err := GetImportPaths(context.Background(), add, "ne", "x.go", "x", t.env); err != nil {
			t.Fatalf("GetImportPaths() = %v", err)
		}
		// Sort, then clear out relevance so it doesn't mess up the DeepEqual.
		sort.Slice(got, func(i, j int) bool {
			ri, rj := got[i], got[j]
			if ri.relevance != rj.relevance {
				return ri.relevance > rj.relevance // Highest first.
			}
			return ri.name < rj.name
		})
		for i := range got {
			got[i].relevance = 0
		}
		if !reflect.DeepEqual(want, got) {
			t.Errorf("wanted results in order %v, got %v", want, got)
		}
	})
}

func TestGetPackageCompletions(t *testing.T) {
	type res struct {
		relevance          float64
		name, path, symbol string
	}
	want := []res{
		{0, "rand", "math/rand", "Seed"},
		{0, "rand", "bar.com/rand", "Bar"},
	}

	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "bar.com",
				Files: fm{"rand/bar.go": "package rand\nvar Bar int\n"},
			},
		},
	}.test(t, func(t *goimportTest) {
		var mu sync.Mutex
		var got []res
		add := func(c PackageExport) {
			mu.Lock()
			defer mu.Unlock()
			for _, csym := range c.Exports {
				for _, w := range want {
					if c.Fix.StmtInfo.ImportPath == w.path && csym.Name == w.symbol {
						got = append(got, res{c.Fix.Relevance, c.Fix.IdentName, c.Fix.StmtInfo.ImportPath, csym.Name})
					}
				}
			}
		}
		if err := GetPackageExports(context.Background(), add, "rand", "x.go", "x", t.env); err != nil {
			t.Fatalf("getPackageCompletions() = %v", err)
		}
		// Sort, then clear out relevance so it doesn't mess up the DeepEqual.
		sort.Slice(got, func(i, j int) bool {
			ri, rj := got[i], got[j]
			if ri.relevance != rj.relevance {
				return ri.relevance > rj.relevance // Highest first.
			}
			return ri.name < rj.name
		})
		for i := range got {
			got[i].relevance = 0
		}
		if !reflect.DeepEqual(want, got) {
			t.Errorf("wanted results in order %v, got %v", want, got)
		}
	})
}

// Tests #34895: process should not panic on concurrent calls.
func TestConcurrentProcess(t *testing.T) {
	testConfig{
		module: packagestest.Module{
			Name: "foo.com",
			Files: fm{
				"p/first.go": `package foo

func _() {
	fmt.Println()
}
`,
				"p/second.go": `package foo

import "fmt"

func _() {
	fmt.Println()
	imports.Bar() // not imported.
}
`,
			},
		},
	}.test(t, func(t *goimportTest) {
		var (
			n  = 10
			wg sync.WaitGroup
		)
		wg.Add(n)
		for range n {
			go func() {
				defer wg.Done()
				_, err := t.process("foo.com", "p/first.go", nil, nil)
				if err != nil {
					t.Error(err)
				}
			}()
		}
		wg.Wait()
	})
}

func TestNonlocalDot(t *testing.T) {
	const input = `package main
import (
	"fmt"
)
var _, _ = fmt.Sprintf, dot.Dot
`
	const want = `package main

import (
	"fmt"
	"noninternet/dot.v1/dot"
)

var _, _ = fmt.Sprintf, dot.Dot
`
	testConfig{
		modules: []packagestest.Module{
			{
				Name:  "golang.org/fake",
				Files: fm{"x.go": input},
			},
			{
				Name: "noninternet/dot.v1",
				Files: fm{
					"dot/dot.go": "package dot\nfunc Dot(){}\n",
				},
			},
		},
		gopathOnly: true, // our modules testing setup doesn't allow modules without dots.
	}.processTest(t, "golang.org/fake", "x.go", nil, nil, want)
}

func TestSymbolSearchStarvation(t *testing.T) {
	// This test verifies the fix for golang/go#67923: searching through
	// candidates should not starve when the context is cancelled.
	//
	// To reproduce the conditions that led to starvation, cancel the context
	// half way through the search, by leveraging the loadExports callback.
	const candCount = 100
	var loaded atomic.Int32
	ctx, cancel := context.WithCancel(context.Background())
	searcher := symbolSearcher{
		logf:   t.Logf,
		srcDir: "/path/to/foo",
		loadExports: func(ctx context.Context, pkg *pkg, includeTest bool) (string, []stdlib.Symbol, error) {
			if loaded.Add(1) > candCount/2 {
				cancel()
			}
			return "bar", []stdlib.Symbol{
				{Name: "A", Kind: stdlib.Var},
				{Name: "B", Kind: stdlib.Var},
				// Missing: "C", so that none of these packages match.
			}, nil
		},
	}

	var candidates []pkgDistance
	for i := range candCount {
		name := fmt.Sprintf("bar%d", i)
		candidates = append(candidates, pkgDistance{
			pkg: &pkg{
				dir:             path.Join(searcher.srcDir, name),
				importPathShort: "foo/" + name,
				packageName:     name,
				relevance:       1,
			},
			distance: 1,
		})
	}

	// We don't actually care what happens, as long as it doesn't deadlock!
	_, err := searcher.search(ctx, candidates, "bar", map[string]bool{"A": true, "B": true, "C": true})
	t.Logf("search completed with err: %v", err)
}

func TestMatchesPath(t *testing.T) {
	tests := []struct {
		ident string
		path  string
		want  bool
	}{
		// degenerate cases
		{"", "", true},
		{"", "x", false},
		{"x", "", false},

		// full segment matching
		{"x", "x", true},
		{"x", "y", false},
		{"x", "wx", false},
		{"x", "path/to/x", true},
		{"mypkg", "path/to/mypkg", true},
		{"x", "path/to/xy", false},
		{"x", "path/to/x/y", true},
		{"mypkg", "path/to/mypkg/y", true},
		{"x", "path/to/x/v3", true},

		// subsegment matching
		{"x", "path/to/x-go", true},
		{"foo", "path/to/go-foo", true},
		{"go", "path/to/go-foo", true},
		{"gofoo", "path/to/go-foo", true},
		{"gofoo", "path/to/go-foo-bar", false},
		{"foo", "path/to/go-foo-bar", true},
		{"bar", "path/to/go-foo-bar", true},
		{"gofoobar", "path/to/go-foo-bar", true},
		{"x", "path/to/x.v3", true},
		{"x", "path/to/xy.v3", false},
		{"x", "path/to/wx.v3", false},

		// case insensitivity
		{"MyPkg", "path/to/mypkg", true},
		{"myPkg", "path/to/MyPkg", true},

		// multi-byte runes
		{"世界", "path/to/世界", true},
		{"世界", "path/to/世界/foo", true},
		{"世界", "path/to/go-世界/foo", true},
		{"世界", "path/to/世/foo", false},
	}

	for _, test := range tests {
		if got := matchesPath(test.ident, test.path); got != test.want {
			t.Errorf("matchesPath(%q, %q) = %v, want %v", test.ident, test.path, got, test.want)
		}
	}
}

func BenchmarkMatchesPath(b *testing.B) {
	// A collection of calls that exercise different kinds of matching.
	tests := map[string][]struct {
		ident string
		path  string
		want  bool
	}{
		"easy": { // lower case ascii
			{"mypkg", "path/to/mypkg/y", true},
			{"foo", "path/to/go-foo-bar", true},
			{"gofoo", "path/to/go-foo-bar-baz", false},
		},
		"hard": {
			{"MyPkg", "path/to/mypkg", true},
			{"世界", "path/to/go-世界-pkg/foo", true},
			{"longpkgname", "cloud.google.com/Go/Spanner/Admin/Database/longpkgname", true},
		},
	}

	for name, tests := range tests {
		b.Run(name, func(b *testing.B) {
			for b.Loop() {
				for _, test := range tests {
					if got := matchesPath(test.ident, test.path); got != test.want {
						b.Errorf("matchesPath(%q, %q) = %v, want %v", test.ident, test.path, got, test.want)
					}
				}
			}
		})
	}
}


================================================
FILE: internal/imports/imports.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package imports implements a Go pretty-printer (like package "go/format")
// that also adds or removes import statements as necessary.
package imports

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/printer"
	"go/token"
	"io"
	"regexp"
	"strconv"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/internal/event"
)

// Options is golang.org/x/tools/imports.Options with extra internal-only options.
type Options struct {
	Env *ProcessEnv // The environment to use. Note: this contains the cached module and filesystem state.

	// LocalPrefix is a comma-separated string of import path prefixes, which, if
	// set, instructs Process to sort the import paths with the given prefixes
	// into another group after 3rd-party packages.
	LocalPrefix string

	Fragment  bool // Accept fragment of a source file (no package statement)
	AllErrors bool // Report all errors (not just the first 10 on different lines)

	Comments  bool // Print comments (true if nil *Options provided)
	TabIndent bool // Use tabs for indent (true if nil *Options provided)
	TabWidth  int  // Tab width (8 if nil *Options provided)

	FormatOnly bool // Disable the insertion and deletion of imports
}

// Process implements golang.org/x/tools/imports.Process with explicit context in opt.Env.
func Process(filename string, src []byte, opt *Options) (formatted []byte, err error) {
	fileSet := token.NewFileSet()
	var parserMode parser.Mode
	if opt.Comments {
		parserMode |= parser.ParseComments
	}
	if opt.AllErrors {
		parserMode |= parser.AllErrors
	}
	file, adjust, err := parse(fileSet, filename, src, parserMode, opt.Fragment)
	if err != nil {
		return nil, err
	}

	if !opt.FormatOnly {
		if err := fixImports(fileSet, file, filename, opt.Env); err != nil {
			return nil, err
		}
	}
	return formatFile(fileSet, file, src, adjust, opt)
}

// FixImports returns a list of fixes to the imports that, when applied,
// will leave the imports in the same state as Process. src and opt must
// be specified.
//
// Note that filename's directory influences which imports can be chosen,
// so it is important that filename be accurate.
func FixImports(ctx context.Context, filename string, src []byte, goroot string, logf func(string, ...any), source Source) (fixes []*ImportFix, err error) {
	ctx, done := event.Start(ctx, "imports.FixImports")
	defer done()

	fileSet := token.NewFileSet()
	// TODO(rfindley): these default values for ParseComments and AllErrors were
	// extracted from gopls, but are they even needed?
	file, _, err := parse(fileSet, filename, src, parser.ParseComments|parser.AllErrors, true)
	if err != nil {
		return nil, err
	}

	return getFixesWithSource(ctx, fileSet, file, filename, goroot, logf, source)
}

// ApplyFixes applies all of the fixes to the file and formats it. extraMode
// is added in when parsing the file. src and opts must be specified, but no
// env is needed.
func ApplyFixes(fixes []*ImportFix, filename string, src []byte, opt *Options, extraMode parser.Mode) (formatted []byte, err error) {
	// Don't use parse() -- we don't care about fragments or statement lists
	// here, and we need to work with unparsable files.
	fileSet := token.NewFileSet()
	parserMode := parser.SkipObjectResolution
	if opt.Comments {
		parserMode |= parser.ParseComments
	}
	if opt.AllErrors {
		parserMode |= parser.AllErrors
	}
	parserMode |= extraMode

	file, err := parser.ParseFile(fileSet, filename, src, parserMode)
	if file == nil {
		return nil, err
	}

	// Apply the fixes to the file.
	apply(fileSet, file, fixes)

	return formatFile(fileSet, file, src, nil, opt)
}

// formatFile formats the file syntax tree.
// It may mutate the token.FileSet and the ast.File.
//
// If an adjust function is provided, it is called after formatting
// with the original source (formatFile's src parameter) and the
// formatted file, and returns the postpocessed result.
func formatFile(fset *token.FileSet, file *ast.File, src []byte, adjust func(orig []byte, src []byte) []byte, opt *Options) ([]byte, error) {
	mergeImports(file)
	sortImports(opt.LocalPrefix, fset.File(file.FileStart), file)
	var spacesBefore []string // import paths we need spaces before
	for _, impSection := range astutil.Imports(fset, file) {
		// Within each block of contiguous imports, see if any
		// import lines are in different group numbers. If so,
		// we'll need to put a space between them so it's
		// compatible with gofmt.
		lastGroup := -1
		for _, importSpec := range impSection {
			importPath, _ := strconv.Unquote(importSpec.Path.Value)
			groupNum := importGroup(opt.LocalPrefix, importPath)
			if groupNum != lastGroup && lastGroup != -1 {
				spacesBefore = append(spacesBefore, importPath)
			}
			lastGroup = groupNum
		}

	}

	printerMode := printer.UseSpaces
	if opt.TabIndent {
		printerMode |= printer.TabIndent
	}
	printConfig := &printer.Config{Mode: printerMode, Tabwidth: opt.TabWidth}

	var buf bytes.Buffer
	err := printConfig.Fprint(&buf, fset, file)
	if err != nil {
		return nil, err
	}
	out := buf.Bytes()
	if adjust != nil {
		out = adjust(src, out)
	}
	if len(spacesBefore) > 0 {
		out, err = addImportSpaces(bytes.NewReader(out), spacesBefore)
		if err != nil {
			return nil, err
		}
	}

	out, err = format.Source(out)
	if err != nil {
		return nil, err
	}
	return out, nil
}

// parse parses src, which was read from filename,
// as a Go source file or statement list.
func parse(fset *token.FileSet, filename string, src []byte, parserMode parser.Mode, fragment bool) (*ast.File, func(orig, src []byte) []byte, error) {
	if parserMode&parser.SkipObjectResolution != 0 {
		panic("legacy ast.Object resolution is required")
	}

	// Try as whole source file.
	file, err := parser.ParseFile(fset, filename, src, parserMode)
	if err == nil {
		return file, nil, nil
	}
	// If the error is that the source file didn't begin with a
	// package line and we accept fragmented input, fall through to
	// try as a source fragment.  Stop and return on any other error.
	if !fragment || !strings.Contains(err.Error(), "expected 'package'") {
		return nil, nil, err
	}

	// If this is a declaration list, make it a source file
	// by inserting a package clause.
	// Insert using a ;, not a newline, so that parse errors are on
	// the correct line.
	const prefix = "package main;"
	psrc := append([]byte(prefix), src...)
	file, err = parser.ParseFile(fset, filename, psrc, parserMode)
	if err == nil {
		// Gofmt will turn the ; into a \n.
		// Do that ourselves now and update the file contents,
		// so that positions and line numbers are correct going forward.
		psrc[len(prefix)-1] = '\n'
		fset.File(file.Package).SetLinesForContent(psrc)

		// If a main function exists, we will assume this is a main
		// package and leave the file.
		if containsMainFunc(file) {
			return file, nil, nil
		}

		adjust := func(orig, src []byte) []byte {
			// Remove the package clause.
			src = src[len(prefix):]
			return matchSpace(orig, src)
		}
		return file, adjust, nil
	}
	// If the error is that the source file didn't begin with a
	// declaration, fall through to try as a statement list.
	// Stop and return on any other error.
	if !strings.Contains(err.Error(), "expected declaration") {
		return nil, nil, err
	}

	// If this is a statement list, make it a source file
	// by inserting a package clause and turning the list
	// into a function body.  This handles expressions too.
	// Insert using a ;, not a newline, so that the line numbers
	// in fsrc match the ones in src.
	fsrc := append(append([]byte("package p; func _() {"), src...), '}')
	file, err = parser.ParseFile(fset, filename, fsrc, parserMode)
	if err == nil {
		adjust := func(orig, src []byte) []byte {
			// Remove the wrapping.
			// Gofmt has turned the ; into a \n\n.
			src = src[len("package p\n\nfunc _() {"):]
			src = src[:len(src)-len("}\n")]
			// Gofmt has also indented the function body one level.
			// Remove that indent.
			src = bytes.ReplaceAll(src, []byte("\n\t"), []byte("\n"))
			return matchSpace(orig, src)
		}
		return file, adjust, nil
	}

	// Failed, and out of options.
	return nil, nil, err
}

// containsMainFunc checks if a file contains a function declaration with the
// function signature 'func main()'
func containsMainFunc(file *ast.File) bool {
	for _, decl := range file.Decls {
		if f, ok := decl.(*ast.FuncDecl); ok {
			if f.Name.Name != "main" {
				continue
			}

			if len(f.Type.Params.List) != 0 {
				continue
			}

			if f.Type.Results != nil && len(f.Type.Results.List) != 0 {
				continue
			}

			return true
		}
	}

	return false
}

func cutSpace(b []byte) (before, middle, after []byte) {
	i := 0
	for i < len(b) && (b[i] == ' ' || b[i] == '\t' || b[i] == '\n') {
		i++
	}
	j := len(b)
	for j > 0 && (b[j-1] == ' ' || b[j-1] == '\t' || b[j-1] == '\n') {
		j--
	}
	if i <= j {
		return b[:i], b[i:j], b[j:]
	}
	return nil, nil, b[j:]
}

// matchSpace reformats src to use the same space context as orig.
//  1. If orig begins with blank lines, matchSpace inserts them at the beginning of src.
//  2. matchSpace copies the indentation of the first non-blank line in orig
//     to every non-blank line in src.
//  3. matchSpace copies the trailing space from orig and uses it in place
//     of src's trailing space.
func matchSpace(orig []byte, src []byte) []byte {
	before, _, after := cutSpace(orig)
	i := bytes.LastIndex(before, []byte{'\n'})
	before, indent := before[:i+1], before[i+1:]

	_, src, _ = cutSpace(src)

	var b bytes.Buffer
	b.Write(before)
	for len(src) > 0 {
		line := src
		if i := bytes.IndexByte(line, '\n'); i >= 0 {
			line, src = line[:i+1], line[i+1:]
		} else {
			src = nil
		}
		if len(line) > 0 && line[0] != '\n' { // not blank
			b.Write(indent)
		}
		b.Write(line)
	}
	b.Write(after)
	return b.Bytes()
}

var impLine = regexp.MustCompile(`^\s+(?:[\w\.]+\s+)?"(.+?)"`)

func addImportSpaces(r io.Reader, breaks []string) ([]byte, error) {
	var out bytes.Buffer
	in := bufio.NewReader(r)
	inImports := false
	done := false
	for {
		s, err := in.ReadString('\n')
		if err == io.EOF {
			break
		} else if err != nil {
			return nil, err
		}

		if !inImports && !done && strings.HasPrefix(s, "import") {
			inImports = true
		}
		if inImports && (strings.HasPrefix(s, "var") ||
			strings.HasPrefix(s, "func") ||
			strings.HasPrefix(s, "const") ||
			strings.HasPrefix(s, "type")) {
			done = true
			inImports = false
		}
		if inImports && len(breaks) > 0 {
			if m := impLine.FindStringSubmatch(s); m != nil {
				if m[1] == breaks[0] {
					out.WriteByte('\n')
					breaks = breaks[1:]
				}
			}
		}

		fmt.Fprint(&out, s)
	}
	return out.Bytes(), nil
}


================================================
FILE: internal/imports/imports_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"os"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func TestMain(m *testing.M) {
	testenv.ExitIfSmallMachine()
	os.Exit(m.Run())
}


================================================
FILE: internal/imports/mkindex.go
================================================
//go:build ignore

// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Command mkindex creates the file "pkgindex.go" containing an index of the Go
// standard library. The file is intended to be built as part of the imports
// package, so that the package may be used in environments where a GOROOT is
// not available (such as App Engine).
package imports

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/format"
	"go/parser"
	"go/token"
	"log"
	"os"
	"path"
	"path/filepath"
	"strings"
)

var (
	pkgIndex = make(map[string][]pkg)
	exports  = make(map[string]map[string]bool)
)

func main() {
	// Don't use GOPATH.
	ctx := build.Default
	ctx.GOPATH = ""

	// Populate pkgIndex global from GOROOT.
	for _, path := range ctx.SrcDirs() {
		f, err := os.Open(path)
		if err != nil {
			log.Print(err)
			continue
		}
		children, err := f.Readdir(-1)
		f.Close()
		if err != nil {
			log.Print(err)
			continue
		}
		for _, child := range children {
			if child.IsDir() {
				loadPkg(path, child.Name())
			}
		}
	}
	// Populate exports global.
	for _, ps := range pkgIndex {
		for _, p := range ps {
			e := loadExports(p.dir)
			if e != nil {
				exports[p.dir] = e
			}
		}
	}

	// Construct source file.
	var buf bytes.Buffer
	fmt.Fprint(&buf, pkgIndexHead)
	fmt.Fprintf(&buf, "var pkgIndexMaster = %#v\n", pkgIndex)
	fmt.Fprintf(&buf, "var exportsMaster = %#v\n", exports)
	src := buf.Bytes()

	// Replace main.pkg type name with pkg.
	src = bytes.Replace(src, []byte("main.pkg"), []byte("pkg"), -1)
	// Replace actual GOROOT with "/go".
	src = bytes.Replace(src, []byte(ctx.GOROOT), []byte("/go"), -1)
	// Add some line wrapping.
	src = bytes.Replace(src, []byte("}, "), []byte("},\n"), -1)
	src = bytes.Replace(src, []byte("true, "), []byte("true,\n"), -1)

	var err error
	src, err = format.Source(src)
	if err != nil {
		log.Fatal(err)
	}

	// Write out source file.
	err = os.WriteFile("pkgindex.go", src, 0644)
	if err != nil {
		log.Fatal(err)
	}
}

const pkgIndexHead = `package imports

func init() {
	pkgIndexOnce.Do(func() {
		pkgIndex.m = pkgIndexMaster
	})
	loadExports = func(dir string) map[string]bool {
		return exportsMaster[dir]
	}
}
`

type pkg struct {
	importpath string // full pkg import path, e.g. "net/http"
	dir        string // absolute file path to pkg directory e.g. "/usr/lib/go/src/fmt"
}

var fset = token.NewFileSet()

func loadPkg(root, importpath string) {
	shortName := path.Base(importpath)
	if shortName == "testdata" {
		return
	}

	dir := filepath.Join(root, importpath)
	pkgIndex[shortName] = append(pkgIndex[shortName], pkg{
		importpath: importpath,
		dir:        dir,
	})

	pkgDir, err := os.Open(dir)
	if err != nil {
		return
	}
	children, err := pkgDir.Readdir(-1)
	pkgDir.Close()
	if err != nil {
		return
	}
	for _, child := range children {
		name := child.Name()
		if name == "" {
			continue
		}
		if c := name[0]; c == '.' || ('0' <= c && c <= '9') {
			continue
		}
		if child.IsDir() {
			loadPkg(root, filepath.Join(importpath, name))
		}
	}
}

func loadExports(dir string) map[string]bool {
	exports := make(map[string]bool)
	buildPkg, err := build.ImportDir(dir, 0)
	if err != nil {
		if strings.Contains(err.Error(), "no buildable Go source files in") {
			return nil
		}
		log.Printf("could not import %q: %v", dir, err)
		return nil
	}
	for _, file := range buildPkg.GoFiles {
		// Legacy ast.Object resolution is needed here.
		f, err := parser.ParseFile(fset, filepath.Join(dir, file), nil, 0)
		if err != nil {
			log.Printf("could not parse %q: %v", file, err)
			continue
		}
		for name := range f.Scope.Objects {
			if ast.IsExported(name) {
				exports[name] = true
			}
		}
	}
	return exports
}


================================================
FILE: internal/imports/mod.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"slices"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/mod/module"
	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/gopathwalk"
	"golang.org/x/tools/internal/stdlib"
)

// Notes(rfindley): ModuleResolver appears to be heavily optimized for scanning
// as fast as possible, which is desirable for a call to goimports from the
// command line, but it doesn't work as well for gopls, where it suffers from
// slow startup (golang/go#44863) and intermittent hanging (golang/go#59216),
// both caused by populating the cache, albeit in slightly different ways.
//
// A high level list of TODOs:
//  - Optimize the scan itself, as there is some redundancy statting and
//    reading go.mod files.
//  - Invert the relationship between ProcessEnv and Resolver (see the
//    docstring of ProcessEnv).
//  - Make it easier to use an external resolver implementation.
//
// Smaller TODOs are annotated in the code below.

// ModuleResolver implements the Resolver interface for a workspace using
// modules.
//
// A goal of the ModuleResolver is to invoke the Go command as little as
// possible. To this end, it runs the Go command only for listing module
// information (i.e. `go list -m -e -json ...`). Package scanning, the process
// of loading package information for the modules, is implemented internally
// via the scan method.
//
// It has two types of state: the state derived from the go command, which
// is populated by init, and the state derived from scans, which is populated
// via scan. A root is considered scanned if it has been walked to discover
// directories. However, if the scan did not require additional information
// from the directory (such as package name or exports), the directory
// information itself may be partially populated. It will be lazily filled in
// as needed by scans, using the scanCallback.
type ModuleResolver struct {
	env *ProcessEnv

	// Module state, populated during construction
	dummyVendorMod *gocommand.ModuleJSON            // if vendoring is enabled, a pseudo-module to represent the /vendor directory
	moduleCacheDir string                           // GOMODCACHE, inferred from GOPATH if unset
	roots          []gopathwalk.Root                // roots to scan, in approximate order of importance
	mains          []*gocommand.ModuleJSON          // main modules
	mainByDir      map[string]*gocommand.ModuleJSON // module information by dir, to join with roots
	modsByModPath  []*gocommand.ModuleJSON          // all modules, ordered by # of path components in their module path
	modsByDir      []*gocommand.ModuleJSON          // ...or by the number of path components in their Dir.

	// Scanning state, populated by scan

	// scanSema prevents concurrent scans, and guards scannedRoots and the cache
	// fields below (though the caches themselves are concurrency safe).
	// Receive to acquire, send to release.
	scanSema     chan struct{}
	scannedRoots map[gopathwalk.Root]bool // if true, root has been walked

	// Caches of directory info, populated by scans and scan callbacks
	//
	// moduleCacheCache stores cached information about roots in the module
	// cache, which are immutable and therefore do not need to be invalidated.
	//
	// otherCache stores information about all other roots (even GOROOT), which
	// may change.
	moduleCacheCache *DirInfoCache
	otherCache       *DirInfoCache
}

// newModuleResolver returns a new module-aware goimports resolver.
//
// Note: use caution when modifying this constructor: changes must also be
// reflected in ModuleResolver.ClearForNewScan.
func newModuleResolver(e *ProcessEnv, moduleCacheCache *DirInfoCache) (*ModuleResolver, error) {
	r := &ModuleResolver{
		env:      e,
		scanSema: make(chan struct{}, 1),
	}
	r.scanSema <- struct{}{} // release

	goenv, err := r.env.goEnv()
	if err != nil {
		return nil, err
	}

	// TODO(rfindley): can we refactor to share logic with r.env.invokeGo?
	inv := gocommand.Invocation{
		BuildFlags: r.env.BuildFlags,
		ModFlag:    r.env.ModFlag,
		Env:        r.env.env(),
		Logf:       r.env.Logf,
		WorkingDir: r.env.WorkingDir,
	}

	vendorEnabled := false
	var mainModVendor *gocommand.ModuleJSON    // for module vendoring
	var mainModsVendor []*gocommand.ModuleJSON // for workspace vendoring

	goWork := r.env.Env["GOWORK"]
	if len(goWork) == 0 {
		// TODO(rfindley): VendorEnabled runs the go command to get GOFLAGS, but
		// they should be available from the ProcessEnv. Can we avoid the redundant
		// invocation?
		vendorEnabled, mainModVendor, err = gocommand.VendorEnabled(context.TODO(), inv, r.env.GocmdRunner)
		if err != nil {
			return nil, err
		}
	} else {
		vendorEnabled, mainModsVendor, err = gocommand.WorkspaceVendorEnabled(context.Background(), inv, r.env.GocmdRunner)
		if err != nil {
			return nil, err
		}
	}

	if vendorEnabled {
		if mainModVendor != nil {
			// Module vendor mode is on, so all the non-Main modules are irrelevant,
			// and we need to search /vendor for everything.
			r.mains = []*gocommand.ModuleJSON{mainModVendor}
			r.dummyVendorMod = &gocommand.ModuleJSON{
				Path: "",
				Dir:  filepath.Join(mainModVendor.Dir, "vendor"),
			}
			r.modsByModPath = []*gocommand.ModuleJSON{mainModVendor, r.dummyVendorMod}
			r.modsByDir = []*gocommand.ModuleJSON{mainModVendor, r.dummyVendorMod}
		} else {
			// Workspace vendor mode is on, so all the non-Main modules are irrelevant,
			// and we need to search /vendor for everything.
			r.mains = mainModsVendor
			r.dummyVendorMod = &gocommand.ModuleJSON{
				Path: "",
				Dir:  filepath.Join(filepath.Dir(goWork), "vendor"),
			}
			r.modsByModPath = append(slices.Clone(mainModsVendor), r.dummyVendorMod)
			r.modsByDir = append(slices.Clone(mainModsVendor), r.dummyVendorMod)
		}
	} else {
		// Vendor mode is off, so run go list -m ... to find everything.
		err := r.initAllMods()
		// We expect an error when running outside of a module with
		// GO111MODULE=on. Other errors are fatal.
		if err != nil {
			if errMsg := err.Error(); !strings.Contains(errMsg, "working directory is not part of a module") && !strings.Contains(errMsg, "go.mod file not found") {
				return nil, err
			}
		}
	}

	r.moduleCacheDir = gomodcacheForEnv(goenv)
	if r.moduleCacheDir == "" {
		return nil, fmt.Errorf("cannot resolve GOMODCACHE")
	}

	sort.Slice(r.modsByModPath, func(i, j int) bool {
		count := func(x int) int {
			return strings.Count(r.modsByModPath[x].Path, "/")
		}
		return count(j) < count(i) // descending order
	})
	sort.Slice(r.modsByDir, func(i, j int) bool {
		count := func(x int) int {
			return strings.Count(r.modsByDir[x].Dir, string(filepath.Separator))
		}
		return count(j) < count(i) // descending order
	})

	r.roots = []gopathwalk.Root{}
	if goenv["GOROOT"] != "" { // "" happens in tests
		r.roots = append(r.roots, gopathwalk.Root{Path: filepath.Join(goenv["GOROOT"], "/src"), Type: gopathwalk.RootGOROOT})
	}
	r.mainByDir = make(map[string]*gocommand.ModuleJSON)
	for _, main := range r.mains {
		r.roots = append(r.roots, gopathwalk.Root{Path: main.Dir, Type: gopathwalk.RootCurrentModule})
		r.mainByDir[main.Dir] = main
	}
	if vendorEnabled {
		r.roots = append(r.roots, gopathwalk.Root{Path: r.dummyVendorMod.Dir, Type: gopathwalk.RootOther})
	} else {
		addDep := func(mod *gocommand.ModuleJSON) {
			if mod.Replace == nil {
				// This is redundant with the cache, but we'll skip it cheaply enough
				// when we encounter it in the module cache scan.
				//
				// Including it at a lower index in r.roots than the module cache dir
				// helps prioritize matches from within existing dependencies.
				r.roots = append(r.roots, gopathwalk.Root{Path: mod.Dir, Type: gopathwalk.RootModuleCache})
			} else {
				r.roots = append(r.roots, gopathwalk.Root{Path: mod.Dir, Type: gopathwalk.RootOther})
			}
		}
		// Walk dependent modules before scanning the full mod cache, direct deps first.
		for _, mod := range r.modsByModPath {
			if !mod.Indirect && !mod.Main {
				addDep(mod)
			}
		}
		for _, mod := range r.modsByModPath {
			if mod.Indirect && !mod.Main {
				addDep(mod)
			}
		}
		// If provided, share the moduleCacheCache.
		//
		// TODO(rfindley): The module cache is immutable. However, the loaded
		// exports do depend on GOOS and GOARCH. Fortunately, the
		// ProcessEnv.buildContext does not adjust these from build.DefaultContext
		// (even though it should). So for now, this is OK to share, but we need to
		// add logic for handling GOOS/GOARCH.
		r.moduleCacheCache = moduleCacheCache
		r.roots = append(r.roots, gopathwalk.Root{Path: r.moduleCacheDir, Type: gopathwalk.RootModuleCache})
	}

	r.scannedRoots = map[gopathwalk.Root]bool{}
	if r.moduleCacheCache == nil {
		r.moduleCacheCache = NewDirInfoCache()
	}
	r.otherCache = NewDirInfoCache()
	return r, nil
}

// gomodcacheForEnv returns the GOMODCACHE value to use based on the given env
// map, which must have GOMODCACHE and GOPATH populated.
//
// TODO(rfindley): this is defensive refactoring.
//  1. Is this even relevant anymore? Can't we just read GOMODCACHE.
//  2. Use this to separate module cache scanning from other scanning.
func gomodcacheForEnv(goenv map[string]string) string {
	if gmc := goenv["GOMODCACHE"]; gmc != "" {
		// golang/go#67156: ensure that the module cache is clean, since it is
		// assumed as a prefix to directories scanned by gopathwalk, which are
		// themselves clean.
		return filepath.Clean(gmc)
	}
	gopaths := filepath.SplitList(goenv["GOPATH"])
	if len(gopaths) == 0 {
		return ""
	}
	return filepath.Join(gopaths[0], "/pkg/mod")
}

func (r *ModuleResolver) initAllMods() error {
	stdout, err := r.env.invokeGo(context.TODO(), "list", "-m", "-e", "-json", "...")
	if err != nil {
		return err
	}
	for dec := json.NewDecoder(stdout); dec.More(); {
		mod := &gocommand.ModuleJSON{}
		if err := dec.Decode(mod); err != nil {
			return err
		}
		if mod.Dir == "" {
			r.env.logf("module %v has not been downloaded and will be ignored", mod.Path)
			// Can't do anything with a module that's not downloaded.
			continue
		}
		// golang/go#36193: the go command doesn't always clean paths.
		mod.Dir = filepath.Clean(mod.Dir)
		r.modsByModPath = append(r.modsByModPath, mod)
		r.modsByDir = append(r.modsByDir, mod)
		if mod.Main {
			r.mains = append(r.mains, mod)
		}
	}
	return nil
}

// ClearForNewScan invalidates the last scan.
//
// It preserves the set of roots, but forgets about the set of directories.
// Though it forgets the set of module cache directories, it remembers their
// contents, since they are assumed to be immutable.
func (r *ModuleResolver) ClearForNewScan() Resolver {
	<-r.scanSema // acquire r, to guard scannedRoots
	r2 := &ModuleResolver{
		env:            r.env,
		dummyVendorMod: r.dummyVendorMod,
		moduleCacheDir: r.moduleCacheDir,
		roots:          r.roots,
		mains:          r.mains,
		mainByDir:      r.mainByDir,
		modsByModPath:  r.modsByModPath,

		scanSema:         make(chan struct{}, 1),
		scannedRoots:     make(map[gopathwalk.Root]bool),
		otherCache:       NewDirInfoCache(),
		moduleCacheCache: r.moduleCacheCache,
	}
	r2.scanSema <- struct{}{} // r2 must start released
	// Invalidate root scans. We don't need to invalidate module cache roots,
	// because they are immutable.
	// (We don't support a use case where GOMODCACHE is cleaned in the middle of
	// e.g. a gopls session: the user must restart gopls to get accurate
	// imports.)
	//
	// Scanning for new directories in GOMODCACHE should be handled elsewhere,
	// via a call to ScanModuleCache.
	for _, root := range r.roots {
		if root.Type == gopathwalk.RootModuleCache && r.scannedRoots[root] {
			r2.scannedRoots[root] = true
		}
	}
	r.scanSema <- struct{}{} // release r
	return r2
}

// ClearModuleInfo invalidates resolver state that depends on go.mod file
// contents (essentially, the output of go list -m -json ...).
//
// Notably, it does not forget directory contents, which are reset
// asynchronously via ClearForNewScan.
//
// If the ProcessEnv is a GOPATH environment, ClearModuleInfo is a no op.
//
// TODO(rfindley): move this to a new env.go, consolidating ProcessEnv methods.
func (e *ProcessEnv) ClearModuleInfo() {
	if r, ok := e.resolver.(*ModuleResolver); ok {
		resolver, err := newModuleResolver(e, e.ModCache)
		if err != nil {
			e.resolver = nil
			e.resolverErr = err
			return
		}

		<-r.scanSema // acquire (guards caches)
		resolver.moduleCacheCache = r.moduleCacheCache
		resolver.otherCache = r.otherCache
		r.scanSema <- struct{}{} // release

		e.UpdateResolver(resolver)
	}
}

// UpdateResolver sets the resolver for the ProcessEnv to use in imports
// operations. Only for use with the result of [Resolver.ClearForNewScan].
//
// TODO(rfindley): this awkward API is a result of the (arguably) inverted
// relationship between configuration and state described in the doc comment
// for [ProcessEnv].
func (e *ProcessEnv) UpdateResolver(r Resolver) {
	e.resolver = r
	e.resolverErr = nil
}

// findPackage returns the module and directory from within the main modules
// and their dependencies that contains the package at the given import path,
// or returns nil, "" if no module is in scope.
func (r *ModuleResolver) findPackage(importPath string) (*gocommand.ModuleJSON, string) {
	// This can't find packages in the stdlib, but that's harmless for all
	// the existing code paths.
	for _, m := range r.modsByModPath {
		if !strings.HasPrefix(importPath, m.Path) {
			continue
		}
		pathInModule := importPath[len(m.Path):]
		pkgDir := filepath.Join(m.Dir, pathInModule)
		if r.dirIsNestedModule(pkgDir, m) {
			continue
		}

		if info, ok := r.cacheLoad(pkgDir); ok {
			if loaded, err := info.reachedStatus(nameLoaded); loaded {
				if err != nil {
					continue // No package in this dir.
				}
				return m, pkgDir
			}
			if scanned, err := info.reachedStatus(directoryScanned); scanned && err != nil {
				continue // Dir is unreadable, etc.
			}
			// This is slightly wrong: a directory doesn't have to have an
			// importable package to count as a package for package-to-module
			// resolution. package main or _test files should count but
			// don't.
			// TODO(heschi): fix this.
			if _, err := r.cachePackageName(info); err == nil {
				return m, pkgDir
			}
		}

		// Not cached. Read the filesystem.
		pkgFiles, err := os.ReadDir(pkgDir)
		if err != nil {
			continue
		}
		// A module only contains a package if it has buildable go
		// files in that directory. If not, it could be provided by an
		// outer module. See #29736.
		for _, fi := range pkgFiles {
			if ok, _ := r.env.matchFile(pkgDir, fi.Name()); ok {
				return m, pkgDir
			}
		}
	}
	return nil, ""
}

func (r *ModuleResolver) cacheLoad(dir string) (directoryPackageInfo, bool) {
	if info, ok := r.moduleCacheCache.Load(dir); ok {
		return info, ok
	}
	return r.otherCache.Load(dir)
}

func (r *ModuleResolver) cacheStore(info directoryPackageInfo) {
	if info.rootType == gopathwalk.RootModuleCache {
		r.moduleCacheCache.Store(info.dir, info)
	} else {
		r.otherCache.Store(info.dir, info)
	}
}

// cachePackageName caches the package name for a dir already in the cache.
func (r *ModuleResolver) cachePackageName(info directoryPackageInfo) (string, error) {
	if info.rootType == gopathwalk.RootModuleCache {
		return r.moduleCacheCache.CachePackageName(info)
	}
	return r.otherCache.CachePackageName(info)
}

func (r *ModuleResolver) cacheExports(ctx context.Context, env *ProcessEnv, info directoryPackageInfo) (string, []stdlib.Symbol, error) {
	if info.rootType == gopathwalk.RootModuleCache {
		return r.moduleCacheCache.CacheExports(ctx, env, info)
	}
	return r.otherCache.CacheExports(ctx, env, info)
}

// findModuleByDir returns the module that contains dir, or nil if no such
// module is in scope.
func (r *ModuleResolver) findModuleByDir(dir string) *gocommand.ModuleJSON {
	// This is quite tricky and may not be correct. dir could be:
	// - a package in the main module.
	// - a replace target underneath the main module's directory.
	//    - a nested module in the above.
	// - a replace target somewhere totally random.
	//    - a nested module in the above.
	// - in the mod cache.
	// - in /vendor/ in -mod=vendor mode.
	//    - nested module? Dunno.
	// Rumor has it that replace targets cannot contain other replace targets.
	//
	// Note that it is critical here that modsByDir is sorted to have deeper dirs
	// first. This ensures that findModuleByDir finds the innermost module.
	// See also golang/go#56291.
	for _, m := range r.modsByDir {
		if !strings.HasPrefix(dir, m.Dir) {
			continue
		}

		if r.dirIsNestedModule(dir, m) {
			continue
		}

		return m
	}
	return nil
}

// dirIsNestedModule reports if dir is contained in a nested module underneath
// mod, not actually in mod.
func (r *ModuleResolver) dirIsNestedModule(dir string, mod *gocommand.ModuleJSON) bool {
	if !strings.HasPrefix(dir, mod.Dir) {
		return false
	}
	if r.dirInModuleCache(dir) {
		// Nested modules in the module cache are pruned,
		// so it cannot be a nested module.
		return false
	}
	if mod != nil && mod == r.dummyVendorMod {
		// The /vendor pseudomodule is flattened and doesn't actually count.
		return false
	}
	modDir, _ := r.modInfo(dir)
	if modDir == "" {
		return false
	}
	return modDir != mod.Dir
}

func readModName(modFile string) string {
	modBytes, err := os.ReadFile(modFile)
	if err != nil {
		return ""
	}
	return modulePath(modBytes)
}

func (r *ModuleResolver) modInfo(dir string) (modDir, modName string) {
	if r.dirInModuleCache(dir) {
		if matches := modCacheRegexp.FindStringSubmatch(dir); len(matches) == 3 {
			index := strings.Index(dir, matches[1]+"@"+matches[2])
			modDir := filepath.Join(dir[:index], matches[1]+"@"+matches[2])
			return modDir, readModName(filepath.Join(modDir, "go.mod"))
		}
	}
	for {
		if info, ok := r.cacheLoad(dir); ok {
			return info.moduleDir, info.moduleName
		}
		f := filepath.Join(dir, "go.mod")
		info, err := os.Stat(f)
		if err == nil && !info.IsDir() {
			return dir, readModName(f)
		}

		d := filepath.Dir(dir)
		if len(d) >= len(dir) {
			return "", "" // reached top of file system, no go.mod
		}
		dir = d
	}
}

func (r *ModuleResolver) dirInModuleCache(dir string) bool {
	if r.moduleCacheDir == "" {
		return false
	}
	return strings.HasPrefix(dir, r.moduleCacheDir)
}

func (r *ModuleResolver) loadPackageNames(importPaths []string, srcDir string) (map[string]string, error) {
	names := map[string]string{}
	for _, path := range importPaths {
		// TODO(rfindley): shouldn't this use the dirInfoCache?
		_, packageDir := r.findPackage(path)
		if packageDir == "" {
			continue
		}
		name, err := packageDirToName(packageDir)
		if err != nil {
			continue
		}
		names[path] = name
	}
	return names, nil
}

func (r *ModuleResolver) scan(ctx context.Context, callback *scanCallback) error {
	ctx, done := event.Start(ctx, "imports.ModuleResolver.scan")
	defer done()

	processDir := func(info directoryPackageInfo) {
		// Skip this directory if we were not able to get the package information successfully.
		if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
			return
		}
		pkg, err := r.canonicalize(info)
		if err != nil {
			return
		}
		if !callback.dirFound(pkg) {
			return
		}

		pkg.packageName, err = r.cachePackageName(info)
		if err != nil {
			return
		}
		if !callback.packageNameLoaded(pkg) {
			return
		}

		_, exports, err := r.loadExports(ctx, pkg, false)
		if err != nil {
			return
		}
		callback.exportsLoaded(pkg, exports)
	}

	// Start processing everything in the cache, and listen for the new stuff
	// we discover in the walk below.
	stop1 := r.moduleCacheCache.ScanAndListen(ctx, processDir)
	defer stop1()
	stop2 := r.otherCache.ScanAndListen(ctx, processDir)
	defer stop2()

	// We assume cached directories are fully cached, including all their
	// children, and have not changed. We can skip them.
	skip := func(root gopathwalk.Root, dir string) bool {
		if r.env.SkipPathInScan != nil && root.Type == gopathwalk.RootCurrentModule {
			if root.Path == dir {
				return false
			}

			if r.env.SkipPathInScan(filepath.Clean(dir)) {
				return true
			}
		}

		info, ok := r.cacheLoad(dir)
		if !ok {
			return false
		}
		// This directory can be skipped as long as we have already scanned it.
		// Packages with errors will continue to have errors, so there is no need
		// to rescan them.
		packageScanned, _ := info.reachedStatus(directoryScanned)
		return packageScanned
	}

	add := func(root gopathwalk.Root, dir string) {
		r.cacheStore(r.scanDirForPackage(root, dir))
	}

	// r.roots and the callback are not necessarily safe to use in the
	// goroutine below. Process them eagerly.
	roots := filterRoots(r.roots, callback.rootFound)
	// We can't cancel walks, because we need them to finish to have a usable
	// cache. Instead, run them in a separate goroutine and detach.
	scanDone := make(chan struct{})
	go func() {
		select {
		case <-ctx.Done():
			return
		case <-r.scanSema: // acquire
		}
		defer func() { r.scanSema <- struct{}{} }() // release
		// We have the lock on r.scannedRoots, and no other scans can run.
		for _, root := range roots {
			if ctx.Err() != nil {
				return
			}

			if r.scannedRoots[root] {
				continue
			}
			gopathwalk.WalkSkip([]gopathwalk.Root{root}, add, skip, gopathwalk.Options{Logf: r.env.Logf, ModulesEnabled: true})
			r.scannedRoots[root] = true
		}
		close(scanDone)
	}()
	select {
	case <-ctx.Done():
	case <-scanDone:
	}
	return nil
}

func (r *ModuleResolver) scoreImportPath(ctx context.Context, path string) float64 {
	if stdlib.HasPackage(path) {
		return MaxRelevance
	}
	mod, _ := r.findPackage(path)
	return modRelevance(mod)
}

func modRelevance(mod *gocommand.ModuleJSON) float64 {
	var relevance float64
	switch {
	case mod == nil: // out of scope
		return MaxRelevance - 4
	case mod.Indirect:
		relevance = MaxRelevance - 3
	case !mod.Main:
		relevance = MaxRelevance - 2
	default:
		relevance = MaxRelevance - 1 // main module ties with stdlib
	}

	_, versionString, ok := module.SplitPathVersion(mod.Path)
	if ok {
		index := strings.Index(versionString, "v")
		if index == -1 {
			return relevance
		}
		if versionNumber, err := strconv.ParseFloat(versionString[index+1:], 64); err == nil {
			relevance += versionNumber / 1000
		}
	}

	return relevance
}

// canonicalize gets the result of canonicalizing the packages using the results
// of initializing the resolver from 'go list -m'.
func (r *ModuleResolver) canonicalize(info directoryPackageInfo) (*pkg, error) {
	// Packages in GOROOT are already canonical, regardless of the std/cmd modules.
	if info.rootType == gopathwalk.RootGOROOT {
		return &pkg{
			importPathShort: info.nonCanonicalImportPath,
			dir:             info.dir,
			packageName:     path.Base(info.nonCanonicalImportPath),
			relevance:       MaxRelevance,
		}, nil
	}

	importPath := info.nonCanonicalImportPath
	mod := r.findModuleByDir(info.dir)
	// Check if the directory is underneath a module that's in scope.
	if mod != nil {
		// It is. If dir is the target of a replace directive,
		// our guessed import path is wrong. Use the real one.
		if mod.Dir == info.dir {
			importPath = mod.Path
		} else {
			dirInMod := info.dir[len(mod.Dir)+len("/"):]
			importPath = path.Join(mod.Path, filepath.ToSlash(dirInMod))
		}
	} else if !strings.HasPrefix(importPath, info.moduleName) {
		// The module's name doesn't match the package's import path. It
		// probably needs a replace directive we don't have.
		return nil, fmt.Errorf("package in %q is not valid without a replace statement", info.dir)
	}

	res := &pkg{
		importPathShort: importPath,
		dir:             info.dir,
		relevance:       modRelevance(mod),
	}
	// We may have discovered a package that has a different version
	// in scope already. Canonicalize to that one if possible.
	if _, canonicalDir := r.findPackage(importPath); canonicalDir != "" {
		res.dir = canonicalDir
	}
	return res, nil
}

func (r *ModuleResolver) loadExports(ctx context.Context, pkg *pkg, includeTest bool) (string, []stdlib.Symbol, error) {
	if info, ok := r.cacheLoad(pkg.dir); ok && !includeTest {
		return r.cacheExports(ctx, r.env, info)
	}
	return loadExportsFromFiles(ctx, r.env, pkg.dir, includeTest)
}

func (r *ModuleResolver) scanDirForPackage(root gopathwalk.Root, dir string) directoryPackageInfo {
	subdir := ""
	if prefix := root.Path + string(filepath.Separator); strings.HasPrefix(dir, prefix) {
		subdir = dir[len(prefix):]
	}
	importPath := filepath.ToSlash(subdir)
	if strings.HasPrefix(importPath, "vendor/") {
		// Only enter vendor directories if they're explicitly requested as a root.
		return directoryPackageInfo{
			status: directoryScanned,
			err:    fmt.Errorf("unwanted vendor directory"),
		}
	}
	switch root.Type {
	case gopathwalk.RootCurrentModule:
		importPath = path.Join(r.mainByDir[root.Path].Path, filepath.ToSlash(subdir))
	case gopathwalk.RootModuleCache:
		matches := modCacheRegexp.FindStringSubmatch(subdir)
		if len(matches) == 0 {
			return directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("invalid module cache path: %v", subdir),
			}
		}
		modPath, err := module.UnescapePath(filepath.ToSlash(matches[1]))
		if err != nil {
			r.env.logf("decoding module cache path %q: %v", subdir, err)
			return directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("decoding module cache path %q: %v", subdir, err),
			}
		}
		importPath = path.Join(modPath, filepath.ToSlash(matches[3]))
	}

	modDir, modName := r.modInfo(dir)
	result := directoryPackageInfo{
		status:                 directoryScanned,
		dir:                    dir,
		rootType:               root.Type,
		nonCanonicalImportPath: importPath,
		moduleDir:              modDir,
		moduleName:             modName,
	}
	if root.Type == gopathwalk.RootGOROOT {
		// stdlib packages are always in scope, despite the confusing go.mod
		return result
	}
	return result
}

// modCacheRegexp splits a path in a module cache into module, module version, and package.
var modCacheRegexp = regexp.MustCompile(`(.*)@([^/\\]*)(.*)`)

var (
	slashSlash = []byte("//")
	moduleStr  = []byte("module")
)

// modulePath returns the module path from the gomod file text.
// If it cannot find a module path, it returns an empty string.
// It is tolerant of unrelated problems in the go.mod file.
//
// Copied from cmd/go/internal/modfile.
func modulePath(mod []byte) string {
	for len(mod) > 0 {
		line := mod
		mod = nil
		if i := bytes.IndexByte(line, '\n'); i >= 0 {
			line, mod = line[:i], line[i+1:]
		}
		if i := bytes.Index(line, slashSlash); i >= 0 {
			line = line[:i]
		}
		line = bytes.TrimSpace(line)
		if !bytes.HasPrefix(line, moduleStr) {
			continue
		}
		line = line[len(moduleStr):]
		n := len(line)
		line = bytes.TrimSpace(line)
		if len(line) == n || len(line) == 0 {
			continue
		}

		if line[0] == '"' || line[0] == '`' {
			p, err := strconv.Unquote(string(line))
			if err != nil {
				return "" // malformed quoted string or multiline module path
			}
			return p
		}

		return string(line)
	}
	return "" // missing module path
}


================================================
FILE: internal/imports/mod_cache.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"context"
	"fmt"
	"path"
	"path/filepath"
	"strings"
	"sync"

	"golang.org/x/mod/module"
	"golang.org/x/tools/internal/gopathwalk"
	"golang.org/x/tools/internal/stdlib"
)

// To find packages to import, the resolver needs to know about all of
// the packages that could be imported. This includes packages that are
// already in modules that are in (1) the current module, (2) replace targets,
// and (3) packages in the module cache. Packages in (1) and (2) may change over
// time, as the client may edit the current module and locally replaced modules.
// The module cache (which includes all of the packages in (3)) can only
// ever be added to.
//
// The resolver can thus save state about packages in the module cache
// and guarantee that this will not change over time. To obtain information
// about new modules added to the module cache, the module cache should be
// rescanned.
//
// It is OK to serve information about modules that have been deleted,
// as they do still exist.
// TODO(suzmue): can we share information with the caller about
// what module needs to be downloaded to import this package?

type directoryPackageStatus int

const (
	_ directoryPackageStatus = iota
	directoryScanned
	nameLoaded
	exportsLoaded
)

// directoryPackageInfo holds (possibly incomplete) information about packages
// contained in a given directory.
type directoryPackageInfo struct {
	// status indicates the extent to which this struct has been filled in.
	status directoryPackageStatus
	// err is non-nil when there was an error trying to reach status.
	err error

	// Set when status >= directoryScanned.

	// dir is the absolute directory of this package.
	dir      string
	rootType gopathwalk.RootType
	// nonCanonicalImportPath is the package's expected import path. It may
	// not actually be importable at that path.
	nonCanonicalImportPath string

	// Module-related information.
	moduleDir  string // The directory that is the module root of this dir.
	moduleName string // The module name that contains this dir.

	// Set when status >= nameLoaded.

	packageName string // the package name, as declared in the source.

	// Set when status >= exportsLoaded.
	// TODO(rfindley): it's hard to see this, but exports depend implicitly on
	// the default build context GOOS and GOARCH.
	//
	// We can make this explicit, and key exports by GOOS, GOARCH.
	exports []stdlib.Symbol
}

// reachedStatus returns true when info has a status at least target and any error associated with
// an attempt to reach target.
func (info *directoryPackageInfo) reachedStatus(target directoryPackageStatus) (bool, error) {
	if info.err == nil {
		return info.status >= target, nil
	}
	if info.status == target {
		return true, info.err
	}
	return true, nil
}

// DirInfoCache is a concurrency-safe map for storing information about
// directories that may contain packages.
//
// The information in this cache is built incrementally. Entries are initialized in scan.
// No new keys should be added in any other functions, as all directories containing
// packages are identified in scan.
//
// Other functions, including loadExports and findPackage, may update entries in this cache
// as they discover new things about the directory.
//
// The information in the cache is not expected to change for the cache's
// lifetime, so there is no protection against competing writes. Users should
// take care not to hold the cache across changes to the underlying files.
type DirInfoCache struct {
	mu sync.Mutex
	// dirs stores information about packages in directories, keyed by absolute path.
	dirs      map[string]*directoryPackageInfo
	listeners map[*int]cacheListener
}

func NewDirInfoCache() *DirInfoCache {
	return &DirInfoCache{
		dirs:      make(map[string]*directoryPackageInfo),
		listeners: make(map[*int]cacheListener),
	}
}

type cacheListener func(directoryPackageInfo)

// ScanAndListen calls listener on all the items in the cache, and on anything
// newly added. The returned stop function waits for all in-flight callbacks to
// finish and blocks new ones.
func (d *DirInfoCache) ScanAndListen(ctx context.Context, listener cacheListener) func() {
	ctx, cancel := context.WithCancel(ctx)

	// Flushing out all the callbacks is tricky without knowing how many there
	// are going to be. Setting an arbitrary limit makes it much easier.
	const maxInFlight = 10
	sema := make(chan struct{}, maxInFlight)
	for range maxInFlight {
		sema <- struct{}{}
	}

	cookie := new(int) // A unique ID we can use for the listener.

	// We can't hold mu while calling the listener.
	d.mu.Lock()
	var keys []string
	for key := range d.dirs {
		keys = append(keys, key)
	}
	d.listeners[cookie] = func(info directoryPackageInfo) {
		select {
		case <-ctx.Done():
			return
		case <-sema:
		}
		listener(info)
		sema <- struct{}{}
	}
	d.mu.Unlock()

	stop := func() {
		cancel()
		d.mu.Lock()
		delete(d.listeners, cookie)
		d.mu.Unlock()
		for range maxInFlight {
			<-sema
		}
	}

	// Process the pre-existing keys.
	for _, k := range keys {
		select {
		case <-ctx.Done():
			return stop
		default:
		}
		if v, ok := d.Load(k); ok {
			listener(v)
		}
	}

	return stop
}

// Store stores the package info for dir.
func (d *DirInfoCache) Store(dir string, info directoryPackageInfo) {
	d.mu.Lock()
	// TODO(rfindley, golang/go#59216): should we overwrite an existing entry?
	// That seems incorrect as the cache should be idempotent.
	_, old := d.dirs[dir]
	d.dirs[dir] = &info
	var listeners []cacheListener
	for _, l := range d.listeners {
		listeners = append(listeners, l)
	}
	d.mu.Unlock()

	if !old {
		for _, l := range listeners {
			l(info)
		}
	}
}

// Load returns a copy of the directoryPackageInfo for absolute directory dir.
func (d *DirInfoCache) Load(dir string) (directoryPackageInfo, bool) {
	d.mu.Lock()
	defer d.mu.Unlock()
	info, ok := d.dirs[dir]
	if !ok {
		return directoryPackageInfo{}, false
	}
	return *info, true
}

// Keys returns the keys currently present in d.
func (d *DirInfoCache) Keys() (keys []string) {
	d.mu.Lock()
	defer d.mu.Unlock()
	for key := range d.dirs {
		keys = append(keys, key)
	}
	return keys
}

func (d *DirInfoCache) CachePackageName(info directoryPackageInfo) (string, error) {
	if loaded, err := info.reachedStatus(nameLoaded); loaded {
		return info.packageName, err
	}
	if scanned, err := info.reachedStatus(directoryScanned); !scanned || err != nil {
		return "", fmt.Errorf("cannot read package name, scan error: %v", err)
	}
	info.packageName, info.err = packageDirToName(info.dir)
	info.status = nameLoaded
	d.Store(info.dir, info)
	return info.packageName, info.err
}

func (d *DirInfoCache) CacheExports(ctx context.Context, env *ProcessEnv, info directoryPackageInfo) (string, []stdlib.Symbol, error) {
	if reached, _ := info.reachedStatus(exportsLoaded); reached {
		return info.packageName, info.exports, info.err
	}
	if reached, err := info.reachedStatus(nameLoaded); reached && err != nil {
		return "", nil, err
	}
	info.packageName, info.exports, info.err = loadExportsFromFiles(ctx, env, info.dir, false)
	if info.err == context.Canceled || info.err == context.DeadlineExceeded {
		return info.packageName, info.exports, info.err
	}
	// The cache structure wants things to proceed linearly. We can skip a
	// step here, but only if we succeed.
	if info.status == nameLoaded || info.err == nil {
		info.status = exportsLoaded
	} else {
		info.status = nameLoaded
	}
	d.Store(info.dir, info)
	return info.packageName, info.exports, info.err
}

// ScanModuleCache walks the given directory, which must be a GOMODCACHE value,
// for directory package information, storing the results in cache.
func ScanModuleCache(dir string, cache *DirInfoCache, logf func(string, ...any)) {
	// Note(rfindley): it's hard to see, but this function attempts to implement
	// just the side effects on cache of calling PrimeCache with a ProcessEnv
	// that has the given dir as its GOMODCACHE.
	//
	// Teasing out the control flow, we see that we can avoid any handling of
	// vendor/ and can infer module info entirely from the path, simplifying the
	// logic here.

	root := gopathwalk.Root{
		Path: filepath.Clean(dir),
		Type: gopathwalk.RootModuleCache,
	}

	directoryInfo := func(root gopathwalk.Root, dir string) directoryPackageInfo {
		// This is a copy of ModuleResolver.scanDirForPackage, trimmed down to
		// logic that applies to a module cache directory.

		subdir := ""
		if dir != root.Path {
			subdir = dir[len(root.Path)+len("/"):]
		}

		matches := modCacheRegexp.FindStringSubmatch(subdir)
		if len(matches) == 0 {
			return directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("invalid module cache path: %v", subdir),
			}
		}
		modPath, err := module.UnescapePath(filepath.ToSlash(matches[1]))
		if err != nil {
			if logf != nil {
				logf("decoding module cache path %q: %v", subdir, err)
			}
			return directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("decoding module cache path %q: %v", subdir, err),
			}
		}
		importPath := path.Join(modPath, filepath.ToSlash(matches[3]))
		index := strings.Index(dir, matches[1]+"@"+matches[2])
		modDir := filepath.Join(dir[:index], matches[1]+"@"+matches[2])
		modName := readModName(filepath.Join(modDir, "go.mod"))
		return directoryPackageInfo{
			status:                 directoryScanned,
			dir:                    dir,
			rootType:               root.Type,
			nonCanonicalImportPath: importPath,
			moduleDir:              modDir,
			moduleName:             modName,
		}
	}

	add := func(root gopathwalk.Root, dir string) {
		info := directoryInfo(root, dir)
		cache.Store(info.dir, info)
	}

	skip := func(_ gopathwalk.Root, dir string) bool {
		// Skip directories that have already been scanned.
		//
		// Note that gopathwalk only adds "package" directories, which must contain
		// a .go file, and all such package directories in the module cache are
		// immutable. So if we can load a dir, it can be skipped.
		info, ok := cache.Load(dir)
		if !ok {
			return false
		}
		packageScanned, _ := info.reachedStatus(directoryScanned)
		return packageScanned
	}

	gopathwalk.WalkSkip([]gopathwalk.Root{root}, add, skip, gopathwalk.Options{Logf: logf, ModulesEnabled: true})
}


================================================
FILE: internal/imports/mod_cache_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"fmt"
	"os/exec"
	"reflect"
	"sort"
	"strings"
	"testing"
	"time"
)

func TestDirectoryPackageInfoReachedStatus(t *testing.T) {
	tests := []struct {
		info       directoryPackageInfo
		target     directoryPackageStatus
		wantStatus bool
		wantError  bool
	}{
		{
			info: directoryPackageInfo{
				status: directoryScanned,
				err:    nil,
			},
			target:     directoryScanned,
			wantStatus: true,
		},
		{
			info: directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("error getting to directory scanned"),
			},
			target:     directoryScanned,
			wantStatus: true,
			wantError:  true,
		},
		{
			info:       directoryPackageInfo{},
			target:     directoryScanned,
			wantStatus: false,
		},
	}

	for _, tt := range tests {
		gotStatus, gotErr := tt.info.reachedStatus(tt.target)
		if gotErr != nil {
			if !tt.wantError {
				t.Errorf("unexpected error: %s", gotErr)
			}
			continue
		}

		if tt.wantStatus != gotStatus {
			t.Errorf("reached status expected: %v, got: %v", tt.wantStatus, gotStatus)
		}
	}
}

func TestModCacheInfo(t *testing.T) {
	m := NewDirInfoCache()

	dirInfo := []struct {
		dir  string
		info directoryPackageInfo
	}{
		{
			dir: "mypackage",
			info: directoryPackageInfo{
				status:                 directoryScanned,
				dir:                    "mypackage",
				nonCanonicalImportPath: "example.com/mypackage",
			},
		},
		{
			dir: "bad package",
			info: directoryPackageInfo{
				status: directoryScanned,
				err:    fmt.Errorf("bad package"),
			},
		},
		{
			dir: "mypackage/other",
			info: directoryPackageInfo{
				dir:                    "mypackage/other",
				nonCanonicalImportPath: "example.com/mypackage/other",
			},
		},
	}

	for _, d := range dirInfo {
		m.Store(d.dir, d.info)
	}

	for _, d := range dirInfo {
		val, ok := m.Load(d.dir)
		if !ok {
			t.Errorf("directory not loaded: %s", d.dir)
		}

		if !reflect.DeepEqual(d.info, val) {
			t.Errorf("expected: %v, got: %v", d.info, val)
		}
	}

	var wantKeys []string
	for _, d := range dirInfo {
		wantKeys = append(wantKeys, d.dir)
	}
	sort.Strings(wantKeys)

	gotKeys := m.Keys()
	sort.Strings(gotKeys)

	if len(gotKeys) != len(wantKeys) {
		t.Errorf("different length of keys. expected: %d, got: %d", len(wantKeys), len(gotKeys))
	}

	for i, want := range wantKeys {
		if want != gotKeys[i] {
			t.Errorf("%d: expected %s, got %s", i, want, gotKeys[i])
		}
	}
}

func BenchmarkScanModuleCache(b *testing.B) {
	output, err := exec.Command("go", "env", "GOMODCACHE").Output()
	if err != nil {
		b.Fatal(err)
	}
	gomodcache := strings.TrimSpace(string(output))
	cache := NewDirInfoCache()
	start := time.Now()
	ScanModuleCache(gomodcache, cache, nil)
	b.Logf("initial scan took %v", time.Since(start))

	for b.Loop() {
		ScanModuleCache(gomodcache, cache, nil)
	}
}


================================================
FILE: internal/imports/mod_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"archive/zip"
	"context"
	"fmt"
	"log"
	"os"
	"path/filepath"
	"reflect"
	"regexp"
	"sort"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/mod/module"
	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/gopathwalk"
	"golang.org/x/tools/internal/proxydir"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
	"maps"
	"slices"
)

// Tests that we can find packages in the stdlib.
func TestScanStdlib(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x
`, "")
	defer mt.cleanup()

	mt.assertScanFinds("fmt", "fmt")
}

// Tests that we handle a nested module. This is different from other tests
// where the module is in scope -- here we have to figure out the import path
// without any help from go list.
func TestScanOutOfScopeNestedModule(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

-- x.go --
package x

-- v2/go.mod --
module x

-- v2/x.go --
package x`, "")
	defer mt.cleanup()

	pkg := mt.assertScanFinds("x/v2", "x")
	if pkg != nil && !strings.HasSuffix(filepath.ToSlash(pkg.dir), "main/v2") {
		t.Errorf("x/v2 was found in %v, wanted .../main/v2", pkg.dir)
	}
	// We can't load the package name from the import path, but that should
	// be okay -- if we end up adding this result, we'll add it with a name
	// if necessary.
}

// Tests that we don't find a nested module contained in a local replace target.
// The code for this case is too annoying to write, so it's just ignored.
func TestScanNestedModuleInLocalReplace(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require y v0.0.0
replace y => ./y

-- x.go --
package x

-- y/go.mod --
module y

-- y/y.go --
package y

-- y/z/go.mod --
module y/z

-- y/z/z.go --
package z
`, "")
	defer mt.cleanup()

	mt.assertFound("y", "y")

	scan, err := scanToSlice(mt.env.resolver, nil)
	if err != nil {
		t.Fatal(err)
	}
	for _, pkg := range scan {
		if strings.HasSuffix(filepath.ToSlash(pkg.dir), "main/y/z") {
			t.Errorf("scan found a package %v in dir main/y/z, wanted none", pkg.importPathShort)
		}
	}
}

// Tests that path encoding is handled correctly. Adapted from mod_case.txt.
func TestModCase(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require rsc.io/QUOTE v1.5.2

-- x.go --
package x

import _ "rsc.io/QUOTE/QUOTE"
`, "")
	defer mt.cleanup()
	mt.assertFound("rsc.io/QUOTE/QUOTE", "QUOTE")
}

// Not obviously relevant to goimports. Adapted from mod_domain_root.txt anyway.
func TestModDomainRoot(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require example.com v1.0.0

-- x.go --
package x
import _ "example.com"
`, "")
	defer mt.cleanup()
	mt.assertFound("example.com", "x")
}

// Tests that scanning the module cache > 1 time is able to find the same module.
func TestModMultipleScans(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require example.com v1.0.0

-- x.go --
package x
import _ "example.com"
`, "")
	defer mt.cleanup()

	mt.assertScanFinds("example.com", "x")
	mt.assertScanFinds("example.com", "x")
}

// Tests that scanning the module cache > 1 time is able to find the same module
// in the module cache.
func TestModMultipleScansWithSubdirs(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require rsc.io/quote v1.5.2

-- x.go --
package x
import _ "rsc.io/quote"
`, "")
	defer mt.cleanup()

	mt.assertScanFinds("rsc.io/quote", "quote")
	mt.assertScanFinds("rsc.io/quote", "quote")
}

// Tests that scanning the module cache > 1 after changing a package in module cache to make it unimportable
// is able to find the same module.
func TestModCacheEditModFile(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require rsc.io/quote v1.5.2
-- x.go --
package x
import _ "rsc.io/quote"
`, "")
	defer mt.cleanup()
	found := mt.assertScanFinds("rsc.io/quote", "quote")
	if found == nil {
		t.Fatal("rsc.io/quote not found in initial scan.")
	}

	// Update the go.mod file of example.com so that it changes its module path (not allowed).
	if err := os.Chmod(filepath.Join(found.dir, "go.mod"), 0644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(found.dir, "go.mod"), []byte("module bad.com\n"), 0644); err != nil {
		t.Fatal(err)
	}

	// Test that with its cache of module packages it still finds the package.
	mt.assertScanFinds("rsc.io/quote", "quote")

	// Rewrite the main package so that rsc.io/quote is not in scope.
	if err := os.WriteFile(filepath.Join(mt.env.WorkingDir, "go.mod"), []byte("module x\n"), 0644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(mt.env.WorkingDir, "x.go"), []byte("package x\n"), 0644); err != nil {
		t.Fatal(err)
	}

	// Uninitialize the go.mod dependent cached information and make sure it still finds the package.
	mt.env.ClearModuleInfo()
	mt.assertScanFinds("rsc.io/quote", "quote")
}

// Tests that -mod=vendor works. Adapted from mod_vendor_build.txt.
func TestModVendorBuild(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module m
go 1.12
require rsc.io/sampler v1.3.1
-- x.go --
package x
import _ "rsc.io/sampler"
`, "")
	defer mt.cleanup()

	// Sanity-check the setup.
	mt.assertModuleFoundInDir("rsc.io/sampler", "sampler", `pkg.*mod.*/sampler@.*$`)

	// Populate vendor/ and clear out the mod cache so we can't cheat.
	if _, err := mt.env.invokeGo(context.Background(), "mod", "vendor"); err != nil {
		t.Fatal(err)
	}
	if _, err := mt.env.invokeGo(context.Background(), "clean", "-modcache"); err != nil {
		t.Fatal(err)
	}

	// Clear out the resolver's cache, since we've changed the environment.
	mt.env.Env["GOFLAGS"] = "-mod=vendor"
	mt.env.ClearModuleInfo()
	mt.env.UpdateResolver(mt.env.resolver.ClearForNewScan())
	mt.assertModuleFoundInDir("rsc.io/sampler", "sampler", `/vendor/`)
}

// Tests that -mod=vendor is auto-enabled only for go1.14 and higher.
// Vaguely inspired by mod_vendor_auto.txt.
func TestModVendorAuto(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module m
go 1.14
require rsc.io/sampler v1.3.1
-- x.go --
package x
import _ "rsc.io/sampler"
`, "")
	defer mt.cleanup()

	// Populate vendor/.
	if _, err := mt.env.invokeGo(context.Background(), "mod", "vendor"); err != nil {
		t.Fatal(err)
	}

	wantDir := `/vendor/`

	// Clear out the resolver's module info, since we've changed the environment.
	// (the presence of a /vendor directory affects `go list -m`).
	mt.env.ClearModuleInfo()
	mt.assertModuleFoundInDir("rsc.io/sampler", "sampler", wantDir)
}

// Tests that a module replace works. Adapted from mod_list.txt. We start with
// go.mod2; the first part of the test is irrelevant.
func TestModList(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x
require rsc.io/quote v1.5.1
replace rsc.io/sampler v1.3.0 => rsc.io/sampler v1.3.1

-- x.go --
package x
import _ "rsc.io/quote"
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("rsc.io/sampler", "sampler", `pkg.mod.*/sampler@v1.3.1$`)
}

// Tests that a local replace works. Adapted from mod_local_replace.txt.
func TestModLocalReplace(t *testing.T) {
	mt := setup(t, nil, `
-- x/y/go.mod --
module x/y
require zz v1.0.0
replace zz v1.0.0 => ../z

-- x/y/y.go --
package y
import _ "zz"

-- x/z/go.mod --
module x/z

-- x/z/z.go --
package z
`, "x/y")
	defer mt.cleanup()

	mt.assertFound("zz", "z")
}

// Tests that the package at the root of the main module can be found.
// Adapted from the first part of mod_multirepo.txt.
func TestModMultirepo1(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module rsc.io/quote

-- x.go --
package quote
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("rsc.io/quote", "quote", `/main`)
}

// Tests that a simple module dependency is found. Adapted from the third part
// of mod_multirepo.txt (We skip the case where it doesn't have a go.mod
// entry -- we just don't work in that case.)
func TestModMultirepo3(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module rsc.io/quote

require rsc.io/quote/v2 v2.0.1
-- x.go --
package quote

import _ "rsc.io/quote/v2"
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("rsc.io/quote", "quote", `/main`)
	mt.assertModuleFoundInDir("rsc.io/quote/v2", "quote", `pkg.mod.*/v2@v2.0.1$`)
}

// Tests that a nested module is found in the module cache, even though
// it's checked out. Adapted from the fourth part of mod_multirepo.txt.
func TestModMultirepo4(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module rsc.io/quote
require rsc.io/quote/v2 v2.0.1

-- x.go --
package quote
import _ "rsc.io/quote/v2"

-- v2/go.mod --
package rsc.io/quote/v2

-- v2/x.go --
package quote
import _ "rsc.io/quote/v2"
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("rsc.io/quote", "quote", `/main`)
	mt.assertModuleFoundInDir("rsc.io/quote/v2", "quote", `pkg.mod.*/v2@v2.0.1$`)
}

// Tests a simple module dependency. Adapted from the first part of mod_replace.txt.
func TestModReplace1(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module quoter

require rsc.io/quote/v3 v3.0.0

-- main.go --

package main
`, "")
	defer mt.cleanup()
	mt.assertFound("rsc.io/quote/v3", "quote")
}

// Tests a local replace. Adapted from the second part of mod_replace.txt.
func TestModReplace2(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module quoter

require rsc.io/quote/v3 v3.0.0
replace rsc.io/quote/v3 => ./local/rsc.io/quote/v3
-- main.go --
package main

-- local/rsc.io/quote/v3/go.mod --
module rsc.io/quote/v3

require rsc.io/sampler v1.3.0

-- local/rsc.io/quote/v3/quote.go --
package quote

import "rsc.io/sampler"
`, "")
	defer mt.cleanup()
	mt.assertModuleFoundInDir("rsc.io/quote/v3", "quote", `/local/rsc.io/quote/v3`)
}

// Tests that a module can be replaced by a different module path. Adapted
// from the third part of mod_replace.txt.
func TestModReplace3(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module quoter

require not-rsc.io/quote/v3 v3.1.0
replace not-rsc.io/quote/v3 v3.1.0 => ./local/rsc.io/quote/v3

-- usenewmodule/main.go --
package main

-- local/rsc.io/quote/v3/go.mod --
module rsc.io/quote/v3

require rsc.io/sampler v1.3.0

-- local/rsc.io/quote/v3/quote.go --
package quote

-- local/not-rsc.io/quote/v3/go.mod --
module not-rsc.io/quote/v3

-- local/not-rsc.io/quote/v3/quote.go --
package quote
`, "")
	defer mt.cleanup()
	mt.assertModuleFoundInDir("not-rsc.io/quote/v3", "quote", "local/rsc.io/quote/v3")
}

// Tests more local replaces, notably the case where an outer module provides
// a package that could also be provided by an inner module. Adapted from
// mod_replace_import.txt, with example.com/v changed to /vv because Go 1.11
// thinks /v is an invalid major version.
func TestModReplaceImport(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module example.com/m

replace (
	example.com/a => ./a
	example.com/a/b => ./b
)

replace (
	example.com/x => ./x
	example.com/x/v3 => ./v3
)

replace (
	example.com/y/z/w => ./w
	example.com/y => ./y
)

replace (
	example.com/vv v1.11.0 => ./v11
	example.com/vv v1.12.0 => ./v12
	example.com/vv => ./vv
)

require (
	example.com/a/b v0.0.0
	example.com/x/v3 v3.0.0
	example.com/y v0.0.0
	example.com/y/z/w v0.0.0
	example.com/vv v1.12.0
)
-- m.go --
package main
import (
	_ "example.com/a/b"
	_ "example.com/x/v3"
	_ "example.com/y/z/w"
	_ "example.com/vv"
)
func main() {}

-- a/go.mod --
module a.localhost
-- a/a.go --
package a
-- a/b/b.go--
package b

-- b/go.mod --
module a.localhost/b
-- b/b.go --
package b

-- x/go.mod --
module x.localhost
-- x/x.go --
package x
-- x/v3.go --
package v3
import _ "x.localhost/v3"

-- v3/go.mod --
module x.localhost/v3
-- v3/x.go --
package x

-- w/go.mod --
module w.localhost
-- w/skip/skip.go --
// Package skip is nested below nonexistent package w.
package skip

-- y/go.mod --
module y.localhost
-- y/z/w/w.go --
package w

-- v12/go.mod --
module v.localhost
-- v12/v.go --
package v

-- v11/go.mod --
module v.localhost
-- v11/v.go --
package v

-- vv/go.mod --
module v.localhost
-- vv/v.go --
package v
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("example.com/a/b", "b", `main/b$`)
	mt.assertModuleFoundInDir("example.com/x/v3", "x", `main/v3$`)
	mt.assertModuleFoundInDir("example.com/y/z/w", "w", `main/y/z/w$`)
	mt.assertModuleFoundInDir("example.com/vv", "v", `main/v12$`)
}

// Tests that go.work files are respected.
func TestModWorkspace(t *testing.T) {
	mt := setup(t, nil, `
-- go.work --
go 1.18

use (
	./a
	./b
)
-- a/go.mod --
module example.com/a

go 1.18
-- a/a.go --
package a
-- b/go.mod --
module example.com/b

go 1.18
-- b/b.go --
package b
`, "")
	defer mt.cleanup()

	mt.assertModuleFoundInDir("example.com/a", "a", `main/a$`)
	mt.assertModuleFoundInDir("example.com/b", "b", `main/b$`)
	mt.assertScanFinds("example.com/a", "a")
	mt.assertScanFinds("example.com/b", "b")
}

// Tests replaces in workspaces. Uses the directory layout in the cmd/go
// work_replace test. It tests both that replaces in go.work files are
// respected and that a wildcard replace in go.work overrides a versioned replace
// in go.mod.
func TestModWorkspaceReplace(t *testing.T) {
	mt := setup(t, nil, `
-- go.work --
use m

replace example.com/dep => ./dep
replace example.com/other => ./other2

-- m/go.mod --
module example.com/m

require example.com/dep v1.0.0
require example.com/other v1.0.0

replace example.com/other v1.0.0 => ./other
-- m/m.go --
package m

import "example.com/dep"
import "example.com/other"

func F() {
	dep.G()
	other.H()
}
-- dep/go.mod --
module example.com/dep
-- dep/dep.go --
package dep

func G() {
}
-- other/go.mod --
module example.com/other
-- other/dep.go --
package other

func G() {
}
-- other2/go.mod --
module example.com/other
-- other2/dep.go --
package other2

func G() {
}
`, "")
	defer mt.cleanup()

	mt.assertScanFinds("example.com/m", "m")
	mt.assertScanFinds("example.com/dep", "dep")
	mt.assertModuleFoundInDir("example.com/other", "other2", "main/other2$")
	mt.assertScanFinds("example.com/other", "other2")
}

// Tests a case where conflicting replaces are overridden by a replace
// in the go.work file.
func TestModWorkspaceReplaceOverride(t *testing.T) {
	mt := setup(t, nil, `-- go.work --
use m
use n
replace example.com/dep => ./dep3
-- m/go.mod --
module example.com/m

require example.com/dep v1.0.0
replace example.com/dep => ./dep1
-- m/m.go --
package m

import "example.com/dep"

func F() {
	dep.G()
}
-- n/go.mod --
module example.com/n

require example.com/dep v1.0.0
replace example.com/dep => ./dep2
-- n/n.go --
package n

import "example.com/dep"

func F() {
	dep.G()
}
-- dep1/go.mod --
module example.com/dep
-- dep1/dep.go --
package dep

func G() {
}
-- dep2/go.mod --
module example.com/dep
-- dep2/dep.go --
package dep

func G() {
}
-- dep3/go.mod --
module example.com/dep
-- dep3/dep.go --
package dep

func G() {
}
`, "")

	mt.assertScanFinds("example.com/m", "m")
	mt.assertScanFinds("example.com/n", "n")
	mt.assertScanFinds("example.com/dep", "dep")
	mt.assertModuleFoundInDir("example.com/dep", "dep", "main/dep3$")
}

// Tests that the correct versions of modules are found in
// workspaces with module pruning. This is based on the
// cmd/go mod_prune_all script test.
func TestModWorkspacePrune(t *testing.T) {
	mt := setup(t, nil, `
-- go.work --
go 1.18

use (
	./a
	./p
)

replace example.com/b v1.0.0 => ./b
replace example.com/q v1.0.0 => ./q1_0_0
replace example.com/q v1.0.5 => ./q1_0_5
replace example.com/q v1.1.0 => ./q1_1_0
replace example.com/r v1.0.0 => ./r
replace example.com/w v1.0.0 => ./w
replace example.com/x v1.0.0 => ./x
replace example.com/y v1.0.0 => ./y
replace example.com/z v1.0.0 => ./z1_0_0
replace example.com/z v1.1.0 => ./z1_1_0

-- a/go.mod --
module example.com/a

go 1.18

require example.com/b v1.0.0
require example.com/z v1.0.0
-- a/foo.go --
package main

import "example.com/b"

func main() {
	b.B()
}
-- b/go.mod --
module example.com/b

go 1.18

require example.com/q v1.1.0
-- b/b.go --
package b

func B() {
}
-- p/go.mod --
module example.com/p

go 1.18

require example.com/q v1.0.0

replace example.com/q v1.0.0 => ../q1_0_0
replace example.com/q v1.1.0 => ../q1_1_0
-- p/main.go --
package main

import "example.com/q"

func main() {
	q.PrintVersion()
}
-- q1_0_0/go.mod --
module example.com/q

go 1.18
-- q1_0_0/q.go --
package q

import "fmt"

func PrintVersion() {
	fmt.Println("version 1.0.0")
}
-- q1_0_5/go.mod --
module example.com/q

go 1.18

require example.com/r v1.0.0
-- q1_0_5/q.go --
package q

import _ "example.com/r"
-- q1_1_0/go.mod --
module example.com/q

require example.com/w v1.0.0
require example.com/z v1.1.0

go 1.18
-- q1_1_0/q.go --
package q

import _ "example.com/w"
import _ "example.com/z"

import "fmt"

func PrintVersion() {
	fmt.Println("version 1.1.0")
}
-- r/go.mod --
module example.com/r

go 1.18

require example.com/r v1.0.0
-- r/r.go --
package r
-- w/go.mod --
module example.com/w

go 1.18

require example.com/x v1.0.0
-- w/w.go --
package w
-- w/w_test.go --
package w

import _ "example.com/x"
-- x/go.mod --
module example.com/x

go 1.18
-- x/x.go --
package x
-- x/x_test.go --
package x
import _ "example.com/y"
-- y/go.mod --
module example.com/y

go 1.18
-- y/y.go --
package y
-- z1_0_0/go.mod --
module example.com/z

go 1.18

require example.com/q v1.0.5
-- z1_0_0/z.go --
package z

import _ "example.com/q"
-- z1_1_0/go.mod --
module example.com/z

go 1.18
-- z1_1_0/z.go --
package z
`, "")

	mt.assertScanFinds("example.com/w", "w")
	mt.assertScanFinds("example.com/q", "q")
	mt.assertScanFinds("example.com/x", "x")
	mt.assertScanFinds("example.com/z", "z")
	mt.assertModuleFoundInDir("example.com/w", "w", "main/w$")
	mt.assertModuleFoundInDir("example.com/q", "q", "main/q1_1_0$")
	mt.assertModuleFoundInDir("example.com/x", "x", "main/x$")
	mt.assertModuleFoundInDir("example.com/z", "z", "main/z1_1_0$")
}

// Tests that we handle GO111MODULE=on with no go.mod file. See #30855.
func TestNoMainModule(t *testing.T) {
	mt := setup(t, map[string]string{"GO111MODULE": "on"}, `
-- x.go --
package x
`, "")
	defer mt.cleanup()
	if _, err := mt.env.invokeGo(context.Background(), "mod", "download", "rsc.io/quote@v1.5.1"); err != nil {
		t.Fatal(err)
	}

	mt.assertScanFinds("rsc.io/quote", "quote")
}

// assertFound asserts that the package at importPath is found to have pkgName,
// and that scanning for pkgName finds it at importPath.
func (t *modTest) assertFound(importPath, pkgName string) (string, *pkg) {
	t.Helper()

	names, err := t.env.resolver.loadPackageNames([]string{importPath}, t.env.WorkingDir)
	if err != nil {
		t.Errorf("loading package name for %v: %v", importPath, err)
	}
	if names[importPath] != pkgName {
		t.Errorf("package name for %v = %v, want %v", importPath, names[importPath], pkgName)
	}
	pkg := t.assertScanFinds(importPath, pkgName)

	_, foundDir := t.env.resolver.(*ModuleResolver).findPackage(importPath)
	return foundDir, pkg
}

func (t *modTest) assertScanFinds(importPath, pkgName string) *pkg {
	t.Helper()
	scan, err := scanToSlice(t.env.resolver, nil)
	if err != nil {
		t.Errorf("scan failed: %v", err)
	}
	for _, pkg := range scan {
		if pkg.importPathShort == importPath {
			return pkg
		}
	}
	t.Errorf("scanning for %v did not find %v", pkgName, importPath)
	return nil
}

func scanToSlice(resolver Resolver, exclude []gopathwalk.RootType) ([]*pkg, error) {
	var mu sync.Mutex
	var result []*pkg
	filter := &scanCallback{
		rootFound: func(root gopathwalk.Root) bool {
			return !slices.Contains(exclude, root.Type)
		},
		dirFound: func(pkg *pkg) bool {
			return true
		},
		packageNameLoaded: func(pkg *pkg) bool {
			mu.Lock()
			defer mu.Unlock()
			result = append(result, pkg)
			return false
		},
	}
	err := resolver.scan(context.Background(), filter)
	return result, err
}

// assertModuleFoundInDir is the same as assertFound, but also checks that the
// package was found in an active module whose Dir matches dirRE.
func (t *modTest) assertModuleFoundInDir(importPath, pkgName, dirRE string) {
	t.Helper()
	dir, pkg := t.assertFound(importPath, pkgName)
	re, err := regexp.Compile(dirRE)
	if err != nil {
		t.Fatal(err)
	}

	if dir == "" {
		t.Errorf("import path %v not found in active modules", importPath)
	} else {
		if !re.MatchString(filepath.ToSlash(dir)) {
			t.Errorf("finding dir for %s: dir = %q did not match regex %q", importPath, dir, dirRE)
		}
	}
	if pkg != nil {
		if !re.MatchString(filepath.ToSlash(pkg.dir)) {
			t.Errorf("scanning for %s: dir = %q did not match regex %q", pkgName, pkg.dir, dirRE)
		}
	}
}

var proxyOnce sync.Once
var proxyDir string

type modTest struct {
	*testing.T
	env     *ProcessEnv
	gopath  string
	cleanup func()
}

// setup builds a test environment from a txtar and supporting modules
// in testdata/mod, along the lines of TestScript in cmd/go.
//
// extraEnv is applied on top of the default test env.
func setup(t *testing.T, extraEnv map[string]string, main, wd string) *modTest {
	t.Helper()
	testenv.NeedsTool(t, "go")

	proxyOnce.Do(func() {
		var err error
		proxyDir, err = os.MkdirTemp("", "proxy-")
		if err != nil {
			t.Fatal(err)
		}
		if err := writeProxy(proxyDir, "testdata/mod"); err != nil {
			t.Fatal(err)
		}
	})

	dir, err := os.MkdirTemp("", t.Name())
	if err != nil {
		t.Fatal(err)
	}

	mainDir := filepath.Join(dir, "main")
	if err := writeModule(mainDir, main); err != nil {
		t.Fatal(err)
	}

	env := &ProcessEnv{
		Env: map[string]string{
			"GOPATH":      filepath.Join(dir, "gopath"),
			"GOMODCACHE":  "",
			"GO111MODULE": "auto",
			"GOSUMDB":     "off",
			"GOPROXY":     proxydir.ToURL(proxyDir),
		},
		WorkingDir:  filepath.Join(mainDir, wd),
		GocmdRunner: &gocommand.Runner{},
	}
	maps.Copy(env.Env, extraEnv)
	if *testDebug {
		env.Logf = log.Printf
	}
	// go mod download gets mad if we don't have a go.mod, so make sure we do.
	_, err = os.Stat(filepath.Join(mainDir, "go.mod"))
	if err != nil && !os.IsNotExist(err) {
		t.Fatalf("checking if go.mod exists: %v", err)
	}
	if err == nil {
		if _, err := env.invokeGo(context.Background(), "mod", "download", "all"); err != nil {
			t.Fatal(err)
		}
	}

	// Ensure the resolver is set for tests that (unsafely) access env.resolver
	// directly.
	//
	// TODO(rfindley): fix this after addressing the TODO in the ProcessEnv
	// docstring.
	if _, err := env.GetResolver(); err != nil {
		t.Fatal(err)
	}

	return &modTest{
		T:       t,
		gopath:  env.Env["GOPATH"],
		env:     env,
		cleanup: func() { removeDir(dir) },
	}
}

// writeModule writes the module in the ar, a txtar, to dir.
func writeModule(dir, ar string) error {
	a := txtar.Parse([]byte(ar))

	for _, f := range a.Files {
		fpath := filepath.Join(dir, f.Name)
		if err := os.MkdirAll(filepath.Dir(fpath), 0755); err != nil {
			return err
		}

		if err := os.WriteFile(fpath, f.Data, 0644); err != nil {
			return err
		}
	}
	return nil
}

// writeProxy writes all the txtar-formatted modules in arDir to a proxy
// directory in dir.
func writeProxy(dir, arDir string) error {
	files, err := os.ReadDir(arDir)
	if err != nil {
		return err
	}

	for _, fi := range files {
		if err := writeProxyModule(dir, filepath.Join(arDir, fi.Name())); err != nil {
			return err
		}
	}
	return nil
}

// writeProxyModule writes a txtar-formatted module at arPath to the module
// proxy in base.
func writeProxyModule(base, arPath string) error {
	arName := filepath.Base(arPath)
	i := strings.LastIndex(arName, "_v")
	ver := strings.TrimSuffix(arName[i+1:], ".txt")
	modDir := strings.ReplaceAll(arName[:i], "_", "/")
	modPath, err := module.UnescapePath(modDir)
	if err != nil {
		return err
	}

	dir := filepath.Join(base, modDir, "@v")
	a, err := txtar.ParseFile(arPath)

	if err != nil {
		return err
	}

	if err := os.MkdirAll(dir, 0755); err != nil {
		return err
	}

	f, err := os.OpenFile(filepath.Join(dir, ver+".zip"), os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	z := zip.NewWriter(f)
	for _, f := range a.Files {
		if f.Name[0] == '.' {
			if err := os.WriteFile(filepath.Join(dir, ver+f.Name), f.Data, 0644); err != nil {
				return err
			}
		} else {
			zf, err := z.Create(modPath + "@" + ver + "/" + f.Name)
			if err != nil {
				return err
			}
			if _, err := zf.Write(f.Data); err != nil {
				return err
			}
		}
	}
	if err := z.Close(); err != nil {
		return err
	}
	if err := f.Close(); err != nil {
		return err
	}

	list, err := os.OpenFile(filepath.Join(dir, "list"), os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	if _, err := fmt.Fprintf(list, "%s\n", ver); err != nil {
		return err
	}
	if err := list.Close(); err != nil {
		return err
	}
	return nil
}

func removeDir(dir string) {
	_ = filepath.Walk(dir, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if info.IsDir() {
			_ = os.Chmod(path, 0777)
		}
		return nil
	})
	_ = os.RemoveAll(dir) // ignore errors
}

// Tests that findModFile can find the mod files from a path in the module cache.
func TestFindModFileModCache(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module x

require rsc.io/quote v1.5.2
-- x.go --
package x
import _ "rsc.io/quote"
`, "")
	defer mt.cleanup()
	want := filepath.Join(mt.gopath, "pkg/mod", "rsc.io/quote@v1.5.2")

	found := mt.assertScanFinds("rsc.io/quote", "quote")
	modDir, _ := mt.env.resolver.(*ModuleResolver).modInfo(found.dir)
	if modDir != want {
		t.Errorf("expected: %s, got: %s", want, modDir)
	}
}

// Tests that crud in the module cache is ignored.
func TestInvalidModCache(t *testing.T) {
	testenv.NeedsTool(t, "go")

	dir, err := os.MkdirTemp("", t.Name())
	if err != nil {
		t.Fatal(err)
	}
	defer removeDir(dir)

	// This doesn't have module@version like it should.
	if err := os.MkdirAll(filepath.Join(dir, "gopath/pkg/mod/sabotage"), 0777); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "gopath/pkg/mod/sabotage/x.go"), []byte("package foo\n"), 0777); err != nil {
		t.Fatal(err)
	}
	env := &ProcessEnv{
		Env: map[string]string{
			"GOPATH":      filepath.Join(dir, "gopath"),
			"GO111MODULE": "on",
			"GOSUMDB":     "off",
		},
		GocmdRunner: &gocommand.Runner{},
		WorkingDir:  dir,
	}
	resolver, err := env.GetResolver()
	if err != nil {
		t.Fatal(err)
	}
	scanToSlice(resolver, nil)
}

func TestGetCandidatesRanking(t *testing.T) {
	mt := setup(t, nil, `
-- go.mod --
module example.com

require rsc.io/quote v1.5.1
require rsc.io/quote/v3 v3.0.0

-- rpackage/x.go --
package rpackage
import (
	_ "rsc.io/quote"
	_ "rsc.io/quote/v3"
)
`, "")
	defer mt.cleanup()

	if _, err := mt.env.invokeGo(context.Background(), "mod", "download", "rsc.io/quote/v2@v2.0.1"); err != nil {
		t.Fatal(err)
	}

	type res struct {
		relevance  float64
		name, path string
	}
	want := []res{
		// Stdlib
		{7, "bytes", "bytes"},
		{7, "http", "net/http"},
		// Main module
		{6, "rpackage", "example.com/rpackage"},
		// Direct module deps with v2+ major version
		{5.003, "quote", "rsc.io/quote/v3"},
		// Direct module deps
		{5, "quote", "rsc.io/quote"},
		// Indirect deps
		{4, "language", "golang.org/x/text/language"},
		// Out of scope modules
		{3, "quote", "rsc.io/quote/v2"},
	}
	var mu sync.Mutex
	var got []res
	add := func(c ImportFix) {
		mu.Lock()
		defer mu.Unlock()
		for _, w := range want {
			if c.StmtInfo.ImportPath == w.path {
				got = append(got, res{c.Relevance, c.IdentName, c.StmtInfo.ImportPath})
			}
		}
	}
	if err := GetAllCandidates(context.Background(), add, "", "foo.go", "foo", mt.env); err != nil {
		t.Fatalf("getAllCandidates() = %v", err)
	}
	sort.Slice(got, func(i, j int) bool {
		ri, rj := got[i], got[j]
		if ri.relevance != rj.relevance {
			return ri.relevance > rj.relevance // Highest first.
		}
		return ri.name < rj.name
	})
	if !reflect.DeepEqual(want, got) {
		t.Errorf("wanted candidates in order %v, got %v", want, got)
	}
}

func BenchmarkModuleResolver_RescanModCache(b *testing.B) {
	env := &ProcessEnv{
		GocmdRunner: &gocommand.Runner{},
		// Uncomment for verbose logging (too verbose to enable by default).
		// Logf:        b.Logf,
	}
	exclude := []gopathwalk.RootType{gopathwalk.RootGOROOT}
	resolver, err := env.GetResolver()
	if err != nil {
		b.Fatal(err)
	}
	start := time.Now()
	scanToSlice(resolver, exclude)
	b.Logf("warming the mod cache took %v", time.Since(start))

	for b.Loop() {
		scanToSlice(resolver, exclude)
		resolver = resolver.ClearForNewScan()
	}
}

func BenchmarkModuleResolver_InitialScan(b *testing.B) {
	for b.Loop() {
		env := &ProcessEnv{
			GocmdRunner: &gocommand.Runner{},
		}
		exclude := []gopathwalk.RootType{gopathwalk.RootGOROOT}
		resolver, err := env.GetResolver()
		if err != nil {
			b.Fatal(err)
		}
		scanToSlice(resolver, exclude)
	}
}

// Tests that go.work files and vendor directory are respected.
func TestModWorkspaceVendoring(t *testing.T) {
	mt := setup(t, nil, `
-- go.work --
go 1.22

use (
	./a
	./b
)
-- a/go.mod --
module example.com/a

go 1.22

require rsc.io/sampler v1.3.1
-- a/a.go --
package a

import _ "rsc.io/sampler"
-- b/go.mod --
module example.com/b

go 1.22
-- b/b.go --
package b
`, "")
	defer mt.cleanup()

	// generate vendor directory
	if _, err := mt.env.invokeGo(context.Background(), "work", "vendor"); err != nil {
		t.Fatal(err)
	}

	// update module resolver
	mt.env.ClearModuleInfo()
	mt.env.UpdateResolver(mt.env.resolver.ClearForNewScan())

	mt.assertModuleFoundInDir("example.com/a", "a", `main/a$`)
	mt.assertScanFinds("example.com/a", "a")
	mt.assertModuleFoundInDir("example.com/b", "b", `main/b$`)
	mt.assertScanFinds("example.com/b", "b")
	mt.assertModuleFoundInDir("rsc.io/sampler", "sampler", `/vendor/`)
}


================================================
FILE: internal/imports/sortimports.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Hacked up copy of go/ast/import.go
// Modified to use a single token.File in preference to a FileSet.

package imports

import (
	"go/ast"
	"go/token"
	"log"
	"reflect"
	"slices"
	"sort"
	"strconv"
)

// sortImports sorts runs of consecutive import lines in import blocks in f.
// It also removes duplicate imports when it is possible to do so without data loss.
//
// It may mutate the token.File and the ast.File.
func sortImports(localPrefix string, tokFile *token.File, f *ast.File) {
	for i, d := range f.Decls {
		d, ok := d.(*ast.GenDecl)
		if !ok || d.Tok != token.IMPORT {
			// Not an import declaration, so we're done.
			// Imports are always first.
			break
		}

		if len(d.Specs) == 0 {
			// Empty import block, remove it.
			f.Decls = slices.Delete(f.Decls, i, i+1)
		}

		if !d.Lparen.IsValid() {
			// Not a block: sorted by default.
			continue
		}

		// Identify and sort runs of specs on successive lines.
		i := 0
		specs := d.Specs[:0]
		for j, s := range d.Specs {
			if j > i && tokFile.Line(s.Pos()) > 1+tokFile.Line(d.Specs[j-1].End()) {
				// j begins a new run.  End this one.
				specs = append(specs, sortSpecs(localPrefix, tokFile, f, d.Specs[i:j])...)
				i = j
			}
		}
		specs = append(specs, sortSpecs(localPrefix, tokFile, f, d.Specs[i:])...)
		d.Specs = specs

		// Deduping can leave a blank line before the rparen; clean that up.
		// Ignore line directives.
		if len(d.Specs) > 0 {
			lastSpec := d.Specs[len(d.Specs)-1]
			lastLine := tokFile.PositionFor(lastSpec.Pos(), false).Line
			if rParenLine := tokFile.PositionFor(d.Rparen, false).Line; rParenLine > lastLine+1 {
				tokFile.MergeLine(rParenLine - 1) // has side effects!
			}
		}
	}
}

// mergeImports merges all the import declarations into the first one.
// Taken from golang.org/x/tools/go/ast/astutil.
// This does not adjust line numbers properly
func mergeImports(f *ast.File) {
	if len(f.Decls) <= 1 {
		return
	}

	// Merge all the import declarations into the first one.
	var first *ast.GenDecl
	for i := 0; i < len(f.Decls); i++ {
		decl := f.Decls[i]
		gen, ok := decl.(*ast.GenDecl)
		if !ok || gen.Tok != token.IMPORT || declImports(gen, "C") {
			continue
		}
		if first == nil {
			first = gen
			continue // Don't touch the first one.
		}
		// We now know there is more than one package in this import
		// declaration. Ensure that it ends up parenthesized.
		first.Lparen = first.Pos()
		// Move the imports of the other import declaration to the first one.
		for _, spec := range gen.Specs {
			updateBasicLitPos(spec.(*ast.ImportSpec).Path, first.Pos())
			first.Specs = append(first.Specs, spec)
		}
		f.Decls = slices.Delete(f.Decls, i, i+1)
		i--
	}
}

// declImports reports whether gen contains an import of path.
// Taken from golang.org/x/tools/go/ast/astutil.
func declImports(gen *ast.GenDecl, path string) bool {
	if gen.Tok != token.IMPORT {
		return false
	}
	for _, spec := range gen.Specs {
		impspec := spec.(*ast.ImportSpec)
		if importPath(impspec) == path {
			return true
		}
	}
	return false
}

func importPath(s ast.Spec) string {
	t, err := strconv.Unquote(s.(*ast.ImportSpec).Path.Value)
	if err == nil {
		return t
	}
	return ""
}

func importName(s ast.Spec) string {
	n := s.(*ast.ImportSpec).Name
	if n == nil {
		return ""
	}
	return n.Name
}

func importComment(s ast.Spec) string {
	c := s.(*ast.ImportSpec).Comment
	if c == nil {
		return ""
	}
	return c.Text()
}

// collapse indicates whether prev may be removed, leaving only next.
func collapse(prev, next ast.Spec) bool {
	if importPath(next) != importPath(prev) || importName(next) != importName(prev) {
		return false
	}
	return prev.(*ast.ImportSpec).Comment == nil
}

type posSpan struct {
	Start token.Pos
	End   token.Pos
}

// sortSpecs sorts the import specs within each import decl.
// It may mutate the token.File.
func sortSpecs(localPrefix string, tokFile *token.File, f *ast.File, specs []ast.Spec) []ast.Spec {
	// Can't short-circuit here even if specs are already sorted,
	// since they might yet need deduplication.
	// A lone import, however, may be safely ignored.
	if len(specs) <= 1 {
		return specs
	}

	// Record positions for specs.
	pos := make([]posSpan, len(specs))
	for i, s := range specs {
		pos[i] = posSpan{s.Pos(), s.End()}
	}

	// Identify comments in this range.
	// Any comment from pos[0].Start to the final line counts.
	lastLine := tokFile.Line(pos[len(pos)-1].End)
	cstart := len(f.Comments)
	cend := len(f.Comments)
	for i, g := range f.Comments {
		if g.Pos() < pos[0].Start {
			continue
		}
		if i < cstart {
			cstart = i
		}
		if tokFile.Line(g.End()) > lastLine {
			cend = i
			break
		}
	}
	comments := f.Comments[cstart:cend]

	// Assign each comment to the import spec preceding it.
	importComment := map[*ast.ImportSpec][]*ast.CommentGroup{}
	specIndex := 0
	for _, g := range comments {
		for specIndex+1 < len(specs) && pos[specIndex+1].Start <= g.Pos() {
			specIndex++
		}
		s := specs[specIndex].(*ast.ImportSpec)
		importComment[s] = append(importComment[s], g)
	}

	// Sort the import specs by import path.
	// Remove duplicates, when possible without data loss.
	// Reassign the import paths to have the same position sequence.
	// Reassign each comment to abut the end of its spec.
	// Sort the comments by new position.
	sort.Sort(byImportSpec{localPrefix, specs})

	// Dedup. Thanks to our sorting, we can just consider
	// adjacent pairs of imports.
	deduped := specs[:0]
	for i, s := range specs {
		if i == len(specs)-1 || !collapse(s, specs[i+1]) {
			deduped = append(deduped, s)
		} else {
			p := s.Pos()
			tokFile.MergeLine(tokFile.Line(p)) // has side effects!
		}
	}
	specs = deduped

	// Fix up comment positions
	for i, s := range specs {
		s := s.(*ast.ImportSpec)
		if s.Name != nil {
			s.Name.NamePos = pos[i].Start
		}
		updateBasicLitPos(s.Path, pos[i].Start)
		s.EndPos = pos[i].End
		nextSpecPos := pos[i].End

		for _, g := range importComment[s] {
			for _, c := range g.List {
				c.Slash = pos[i].End
				nextSpecPos = c.End()
			}
		}
		if i < len(specs)-1 {
			pos[i+1].Start = nextSpecPos
			pos[i+1].End = nextSpecPos
		}
	}

	sort.Sort(byCommentPos(comments))

	// Fixup comments can insert blank lines, because import specs are on different lines.
	// We remove those blank lines here by merging import spec to the first import spec line.
	firstSpecLine := tokFile.Line(specs[0].Pos())
	for _, s := range specs[1:] {
		p := s.Pos()
		line := tokFile.Line(p)
		for previousLine := line - 1; previousLine >= firstSpecLine; {
			// MergeLine can panic. Avoid the panic at the cost of not removing the blank line
			// golang/go#50329
			if previousLine > 0 && previousLine < tokFile.LineCount() {
				tokFile.MergeLine(previousLine) // has side effects!
				previousLine--
			} else {
				// try to gather some data to diagnose how this could happen
				req := "Please report what the imports section of your go file looked like."
				log.Printf("panic avoided: first:%d line:%d previous:%d max:%d. %s",
					firstSpecLine, line, previousLine, tokFile.LineCount(), req)
			}
		}
	}
	return specs
}

type byImportSpec struct {
	localPrefix string
	specs       []ast.Spec // slice of *ast.ImportSpec
}

func (x byImportSpec) Len() int      { return len(x.specs) }
func (x byImportSpec) Swap(i, j int) { x.specs[i], x.specs[j] = x.specs[j], x.specs[i] }
func (x byImportSpec) Less(i, j int) bool {
	ipath := importPath(x.specs[i])
	jpath := importPath(x.specs[j])

	igroup := importGroup(x.localPrefix, ipath)
	jgroup := importGroup(x.localPrefix, jpath)
	if igroup != jgroup {
		return igroup < jgroup
	}

	if ipath != jpath {
		return ipath < jpath
	}
	iname := importName(x.specs[i])
	jname := importName(x.specs[j])

	if iname != jname {
		return iname < jname
	}
	return importComment(x.specs[i]) < importComment(x.specs[j])
}

type byCommentPos []*ast.CommentGroup

func (x byCommentPos) Len() int           { return len(x) }
func (x byCommentPos) Swap(i, j int)      { x[i], x[j] = x[j], x[i] }
func (x byCommentPos) Less(i, j int) bool { return x[i].Pos() < x[j].Pos() }

// updateBasicLitPos updates lit.Pos,
// ensuring that lit.End (if set) is displaced by the same amount.
// (See https://go.dev/issue/76395.)
func updateBasicLitPos(lit *ast.BasicLit, pos token.Pos) {
	len := lit.End() - lit.Pos()
	lit.ValuePos = pos
	// TODO(adonovan): after go1.26, simplify to:
	//   lit.ValueEnd = pos + len
	v := reflect.ValueOf(lit).Elem().FieldByName("ValueEnd")
	if v.IsValid() && v.Int() != 0 {
		v.SetInt(int64(pos + len))
	}
}


================================================
FILE: internal/imports/source.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import "context"

// These types document the APIs below.
//
// TODO(rfindley): consider making these defined types rather than aliases.
type (
	ImportPath  = string
	PackageName = string
	Symbol      = string

	// References is set of References found in a Go file. The first map key is the
	// left hand side of a selector expression, the second key is the right hand
	// side, and the value should always be true.
	References = map[PackageName]map[Symbol]bool
)

// A Result satisfies a missing import.
//
// The Import field describes the missing import spec, and the Package field
// summarizes the package exports.
type Result struct {
	Import  *ImportInfo
	Package *PackageInfo
}

// An ImportInfo represents a single import statement.
type ImportInfo struct {
	ImportPath string // import path, e.g. "crypto/rand".
	Name       string // import name, e.g. "crand", or "" if none.
}

// A PackageInfo represents what's known about a package.
type PackageInfo struct {
	Name    string          // package name in the package declaration, if known
	Exports map[string]bool // set of names of known package level sortSymbols
}

// A Source provides imports to satisfy unresolved references in the file being
// fixed.
type Source interface {
	// LoadPackageNames queries PackageName information for the requested import
	// paths, when operating from the provided srcDir.
	//
	// TODO(rfindley): try to refactor to remove this operation.
	LoadPackageNames(ctx context.Context, srcDir string, paths []ImportPath) (map[ImportPath]PackageName, error)

	// ResolveReferences asks the Source for the best package name to satisfy
	// each of the missing references, in the context of fixing the given
	// filename.
	//
	// Returns a map from package name to a [Result] for that package name that
	// provides the required symbols. Keys may be omitted in the map if no
	// candidates satisfy all missing references for that package name. It is up
	// to each data source to select the best result for each entry in the
	// missing map.
	ResolveReferences(ctx context.Context, filename string, missing References) ([]*Result, error)
}


================================================
FILE: internal/imports/source_env.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"context"
	"path/filepath"
	"strings"
	"sync"

	"golang.org/x/sync/errgroup"
	"golang.org/x/tools/internal/gopathwalk"
)

// ProcessEnvSource implements the [Source] interface using the legacy
// [ProcessEnv] abstraction.
type ProcessEnvSource struct {
	env      *ProcessEnv
	srcDir   string
	filename string
	pkgName  string
}

// NewProcessEnvSource returns a [ProcessEnvSource] wrapping the given
// env, to be used for fixing imports in the file with name filename in package
// named pkgName.
func NewProcessEnvSource(env *ProcessEnv, filename, pkgName string) (*ProcessEnvSource, error) {
	abs, err := filepath.Abs(filename)
	if err != nil {
		return nil, err
	}
	srcDir := filepath.Dir(abs)
	return &ProcessEnvSource{
		env:      env,
		srcDir:   srcDir,
		filename: filename,
		pkgName:  pkgName,
	}, nil
}

func (s *ProcessEnvSource) LoadPackageNames(ctx context.Context, srcDir string, unknown []string) (map[string]string, error) {
	r, err := s.env.GetResolver()
	if err != nil {
		return nil, err
	}
	return r.loadPackageNames(unknown, srcDir)
}

func (s *ProcessEnvSource) ResolveReferences(ctx context.Context, filename string, refs map[string]map[string]bool) ([]*Result, error) {
	var mu sync.Mutex
	found := make(map[string][]pkgDistance)
	callback := &scanCallback{
		rootFound: func(gopathwalk.Root) bool {
			return true // We want everything.
		},
		dirFound: func(pkg *pkg) bool {
			return pkgIsCandidate(filename, refs, pkg)
		},
		packageNameLoaded: func(pkg *pkg) bool {
			if _, want := refs[pkg.packageName]; !want {
				return false
			}
			if pkg.dir == s.srcDir && s.pkgName == pkg.packageName {
				// The candidate is in the same directory and has the
				// same package name. Don't try to import ourselves.
				return false
			}
			if !CanUse(filename, pkg.dir) {
				return false
			}
			mu.Lock()
			defer mu.Unlock()
			found[pkg.packageName] = append(found[pkg.packageName], pkgDistance{pkg, distance(s.srcDir, pkg.dir)})
			return false // We'll do our own loading after we sort.
		},
	}
	resolver, err := s.env.GetResolver()
	if err != nil {
		return nil, err
	}
	if err := resolver.scan(ctx, callback); err != nil {
		return nil, err
	}

	g, ctx := errgroup.WithContext(ctx)

	searcher := symbolSearcher{
		logf:        s.env.logf,
		srcDir:      s.srcDir,
		xtest:       strings.HasSuffix(s.pkgName, "_test"),
		loadExports: resolver.loadExports,
	}

	var resultMu sync.Mutex
	results := make(map[string]*Result, len(refs))
	for pkgName, symbols := range refs {
		g.Go(func() error {
			found, err := searcher.search(ctx, found[pkgName], pkgName, symbols)
			if err != nil {
				return err
			}
			if found == nil {
				return nil // No matching package.
			}

			imp := &ImportInfo{
				ImportPath: found.importPathShort,
			}
			pkg := &PackageInfo{
				Name:    pkgName,
				Exports: symbols,
			}
			resultMu.Lock()
			results[pkgName] = &Result{Import: imp, Package: pkg}
			resultMu.Unlock()
			return nil
		})
	}
	if err := g.Wait(); err != nil {
		return nil, err
	}
	var ans []*Result
	for _, x := range results {
		ans = append(ans, x)
	}
	return ans, nil
}


================================================
FILE: internal/imports/source_modindex.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports

import (
	"context"
	"sync"
	"time"

	"golang.org/x/tools/internal/modindex"
)

// This code is here rather than in the modindex package
// to avoid import loops

// TODO(adonovan): this code is only used by a test in this package.
// Can we delete it? Or is there a plan to call NewIndexSource from
// cmd/goimports?

// implements Source using modindex, so only for module cache.
//
// this is perhaps over-engineered. A new Index is read at first use.
// And then Update is called after every 15 minutes, and a new Index
// is read if the index changed. It is not clear the Mutex is needed.
type IndexSource struct {
	modcachedir string
	mu          sync.Mutex
	index       *modindex.Index // (access via getIndex)
	expires     time.Time
}

// create a new Source. Called from NewView in cache/session.go.
func NewIndexSource(cachedir string) *IndexSource {
	return &IndexSource{modcachedir: cachedir}
}

func (s *IndexSource) LoadPackageNames(ctx context.Context, srcDir string, paths []ImportPath) (map[ImportPath]PackageName, error) {
	/// This is used by goimports to resolve the package names of imports of the
	// current package, which is irrelevant for the module cache.
	return nil, nil
}

func (s *IndexSource) ResolveReferences(ctx context.Context, filename string, missing References) ([]*Result, error) {
	index, err := s.getIndex()
	if err != nil {
		return nil, err
	}
	var cs []modindex.Candidate
	for pkg, nms := range missing {
		for nm := range nms {
			x := index.Lookup(pkg, nm, false)
			cs = append(cs, x...)
		}
	}
	found := make(map[string]*Result)
	for _, c := range cs {
		var x *Result
		if x = found[c.ImportPath]; x == nil {
			x = &Result{
				Import: &ImportInfo{
					ImportPath: c.ImportPath,
					Name:       "",
				},
				Package: &PackageInfo{
					Name:    c.PkgName,
					Exports: make(map[string]bool),
				},
			}
			found[c.ImportPath] = x
		}
		x.Package.Exports[c.Name] = true
	}
	var ans []*Result
	for _, x := range found {
		ans = append(ans, x)
	}
	return ans, nil
}

func (s *IndexSource) getIndex() (*modindex.Index, error) {
	s.mu.Lock()
	defer s.mu.Unlock()

	// (s.index = nil => s.expires is zero,
	// so the first condition is strictly redundant.
	// But it makes the postcondition very clear.)
	if s.index == nil || time.Now().After(s.expires) {
		index, err := modindex.Update(s.modcachedir)
		if err != nil {
			return nil, err
		}
		s.index = index
		s.expires = index.ValidAt.Add(15 * time.Minute) // (refresh period)
	}
	// Inv: s.index != nil

	return s.index, nil
}


================================================
FILE: internal/imports/sourcex_test.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package imports_test

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/internal/imports"
	"golang.org/x/tools/internal/modindex"
)

// There are two cached packages, both resolving foo.Foo,
// but only one resolving foo.Bar
var (
	foo = tpkg{
		repo: "foo.com",
		dir:  "foo@v1.0.0",
		syms: []string{"Foo"},
	}
	foobar = tpkg{
		repo: "bar.com",
		dir:  "foo@v1.0.0",
		syms: []string{"Foo", "Bar"},
	}

	fx = `package main
		var _ = foo.Foo
		var _ = foo.Bar
	`
)

type tpkg struct {
	// all packages are named foo
	repo string   // e.g. foo.com
	dir  string   // e.g., foo@v1.0.0
	syms []string // exported syms
}

func newpkgs(cachedir string, pks ...*tpkg) error {
	for _, p := range pks {
		fname := filepath.Join(cachedir, p.repo, p.dir, "foo.go")
		if err := os.MkdirAll(filepath.Dir(fname), 0755); err != nil {
			return err
		}
		fd, err := os.Create(fname)
		if err != nil {
			return err
		}
		fmt.Fprintf(fd, "package foo\n")
		for _, s := range p.syms {
			fmt.Fprintf(fd, "func %s() {}\n", s)
		}
		if err := fd.Close(); err != nil {
			return err
		}
	}
	return nil
}

func TestSource(t *testing.T) {
	dirs := testDirs(t)
	if err := newpkgs(dirs.cachedir, &foo, &foobar); err != nil {
		t.Fatal(err)
	}
	source := imports.NewIndexSource(dirs.cachedir)
	ctx := context.Background()
	fixes, err := imports.FixImports(ctx, "tfile.go", []byte(fx), "unused", nil, source)
	if err != nil {
		t.Fatal(err)
	}
	opts := imports.Options{}
	// ApplyFixes needs a non-nil opts
	got, err := imports.ApplyFixes(fixes, "tfile.go", []byte(fx), &opts, 0)
	if err != nil {
		t.Fatal(err)
	}

	fxwant := "package main\n\nimport \"bar.com/foo\"\n\nvar _ = foo.Foo\nvar _ = foo.Bar\n"
	if diff := cmp.Diff(string(got), fxwant); diff != "" {
		t.Errorf("FixImports got\n%q, wanted\n%q\ndiff is\n%s", string(got), fxwant, diff)
	}
}

type dirs struct {
	tmpdir   string
	cachedir string
	rootdir  string // goroot if we need it, which we don't
}

func testDirs(t *testing.T) dirs {
	t.Helper()
	dir := t.TempDir()
	modindex.IndexDir = dir
	x := dirs{
		tmpdir:   dir,
		cachedir: filepath.Join(dir, "pkg", "mod"),
		rootdir:  filepath.Join(dir, "root"),
	}
	if err := os.MkdirAll(x.cachedir, 0755); err != nil {
		t.Fatal(err)
	}
	if err := os.MkdirAll(x.rootdir, 0755); err != nil {
		t.Fatal(err)
	}
	return x
}


================================================
FILE: internal/imports/testdata/mod/example.com_v1.0.0.txt
================================================
Written by hand.
Test case for module at root of domain.

-- .mod --
module example.com
-- .info --
{"Version": "v1.0.0"}
-- x.go --
package x


================================================
FILE: internal/imports/testdata/mod/golang.org_x_text_v0.0.0-20170915032832-14c0d48ead0c.txt
================================================
written by hand - just enough to compile rsc.io/sampler, rsc.io/quote

-- .mod --
module golang.org/x/text
-- .info --
{"Version":"v0.0.0-20170915032832-14c0d48ead0c","Name":"v0.0.0-20170915032832-14c0d48ead0c","Short":"14c0d48ead0c","Time":"2017-09-15T03:28:32Z"}
-- go.mod --
module golang.org/x/text
-- unused/unused.go --
package unused
-- language/lang.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is a tiny version of golang.org/x/text.

package language

import "strings"

type Tag string

func Make(s string) Tag { return Tag(s) }

func (t Tag) String() string { return string(t) }

func NewMatcher(tags []Tag) Matcher { return &matcher{tags} }

type Matcher interface {
	Match(...Tag) (Tag, int, int)
}

type matcher struct {
	tags []Tag
}

func (m *matcher) Match(prefs ...Tag) (Tag, int, int) {
	for _, pref := range prefs {
		for _, tag := range m.tags {
			if tag == pref || strings.HasPrefix(string(pref), string(tag+"-")) || strings.HasPrefix(string(tag), string(pref+"-")) {
				return tag, 0, 0
			}
		}
	}
	return m.tags[0], 0, 0
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_!q!u!o!t!e_v1.5.2.txt
================================================
rsc.io/QUOTE v1.5.2

-- .mod --
module rsc.io/QUOTE

require rsc.io/quote v1.5.2
-- .info --
{"Version":"v1.5.2","Name":"","Short":"","Time":"2018-07-15T16:25:34Z"}
-- go.mod --
module rsc.io/QUOTE

require rsc.io/quote v1.5.2
-- QUOTE/quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// PACKAGE QUOTE COLLECTS LOUD SAYINGS.
package QUOTE

import (
	"strings"

	"rsc.io/quote"
)

// HELLO RETURNS A GREETING.
func HELLO() string {
	return strings.ToUpper(quote.Hello())
}

// GLASS RETURNS A USEFUL PHRASE FOR WORLD TRAVELERS.
func GLASS() string {
	return strings.ToUpper(quote.GLASS())
}

// GO RETURNS A GO PROVERB.
func GO() string {
	return strings.ToUpper(quote.GO())
}

// OPT RETURNS AN OPTIMIZATION TRUTH.
func OPT() string {
	return strings.ToUpper(quote.OPT())
}
-- QUOTE/quote_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package QUOTE

import (
	"os"
	"testing"
)

func init() {
	os.Setenv("LC_ALL", "en")
}

func TestHELLO(t *testing.T) {
	hello := "HELLO, WORLD"
	if out := HELLO(); out != hello {
		t.Errorf("HELLO() = %q, want %q", out, hello)
	}
}

func TestGLASS(t *testing.T) {
	glass := "I CAN EAT GLASS AND IT DOESN'T HURT ME."
	if out := GLASS(); out != glass {
		t.Errorf("GLASS() = %q, want %q", out, glass)
	}
}

func TestGO(t *testing.T) {
	go1 := "DON'T COMMUNICATE BY SHARING MEMORY, SHARE MEMORY BY COMMUNICATING."
	if out := GO(); out != go1 {
		t.Errorf("GO() = %q, want %q", out, go1)
	}
}

func TestOPT(t *testing.T) {
	opt := "IF A PROGRAM IS TOO SLOW, IT MUST HAVE A LOOP."
	if out := OPT(); out != opt {
		t.Errorf("OPT() = %q, want %q", out, opt)
	}
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_!q!u!o!t!e_v1.5.3-!p!r!e.txt
================================================
rsc.io/QUOTE v1.5.3-PRE (sigh)

-- .mod --
module rsc.io/QUOTE

require rsc.io/quote v1.5.2
-- .info --
{"Version":"v1.5.3-PRE","Name":"","Short":"","Time":"2018-07-15T16:25:34Z"}
-- go.mod --
module rsc.io/QUOTE

require rsc.io/quote v1.5.2
-- QUOTE/quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// PACKAGE QUOTE COLLECTS LOUD SAYINGS.
package QUOTE

import (
	"strings"

	"rsc.io/quote"
)

// HELLO RETURNS A GREETING.
func HELLO() string {
	return strings.ToUpper(quote.Hello())
}

// GLASS RETURNS A USEFUL PHRASE FOR WORLD TRAVELERS.
func GLASS() string {
	return strings.ToUpper(quote.GLASS())
}

// GO RETURNS A GO PROVERB.
func GO() string {
	return strings.ToUpper(quote.GO())
}

// OPT RETURNS AN OPTIMIZATION TRUTH.
func OPT() string {
	return strings.ToUpper(quote.OPT())
}
-- QUOTE/quote_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package QUOTE

import (
	"os"
	"testing"
)

func init() {
	os.Setenv("LC_ALL", "en")
}

func TestHELLO(t *testing.T) {
	hello := "HELLO, WORLD"
	if out := HELLO(); out != hello {
		t.Errorf("HELLO() = %q, want %q", out, hello)
	}
}

func TestGLASS(t *testing.T) {
	glass := "I CAN EAT GLASS AND IT DOESN'T HURT ME."
	if out := GLASS(); out != glass {
		t.Errorf("GLASS() = %q, want %q", out, glass)
	}
}

func TestGO(t *testing.T) {
	go1 := "DON'T COMMUNICATE BY SHARING MEMORY, SHARE MEMORY BY COMMUNICATING."
	if out := GO(); out != go1 {
		t.Errorf("GO() = %q, want %q", out, go1)
	}
}

func TestOPT(t *testing.T) {
	opt := "IF A PROGRAM IS TOO SLOW, IT MUST HAVE A LOOP."
	if out := OPT(); out != opt {
		t.Errorf("OPT() = %q, want %q", out, opt)
	}
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_quote_v1.5.1.txt
================================================
rsc.io/quote@23179ee8a569

-- .mod --
module "rsc.io/quote"

require "rsc.io/sampler" v1.3.0
-- .info --
{"Version":"v1.5.1","Name":"23179ee8a569bb05d896ae05c6503ec69a19f99f","Short":"23179ee8a569","Time":"2018-02-14T00:58:40Z"}
-- go.mod --
module "rsc.io/quote"

require "rsc.io/sampler" v1.3.0
-- quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package quote collects pithy sayings.
package quote // import "rsc.io/quote"

import "rsc.io/sampler"

// Hello returns a greeting.
func Hello() string {
	return sampler.Hello()
}

// Glass returns a useful phrase for world travelers.
func Glass() string {
	// See http://www.oocities.org/nodotus/hbglass.html.
	return "I can eat glass and it doesn't hurt me."
}

// Go returns a Go proverb.
func Go() string {
	return "Don't communicate by sharing memory, share memory by communicating."
}

// Opt returns an optimization truth.
func Opt() string {
	// Wisdom from ken.
	return "If a program is too slow, it must have a loop."
}
-- quote_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package quote

import (
	"os"
	"testing"
)

func init() {
	os.Setenv("LC_ALL", "en")
}

func TestHello(t *testing.T) {
	hello := "Hello, world."
	if out := Hello(); out != hello {
		t.Errorf("Hello() = %q, want %q", out, hello)
	}
}

func TestGlass(t *testing.T) {
	glass := "I can eat glass and it doesn't hurt me."
	if out := Glass(); out != glass {
		t.Errorf("Glass() = %q, want %q", out, glass)
	}
}

func TestGo(t *testing.T) {
	go1 := "Don't communicate by sharing memory, share memory by communicating."
	if out := Go(); out != go1 {
		t.Errorf("Go() = %q, want %q", out, go1)
	}
}

func TestOpt(t *testing.T) {
	opt := "If a program is too slow, it must have a loop."
	if out := Opt(); out != opt {
		t.Errorf("Opt() = %q, want %q", out, opt)
	}
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_quote_v1.5.2.txt
================================================
rsc.io/quote@v1.5.2

-- .mod --
module "rsc.io/quote"

require "rsc.io/sampler" v1.3.0
-- .info --
{"Version":"v1.5.2","Name":"c4d4236f92427c64bfbcf1cc3f8142ab18f30b22","Short":"c4d4236f9242","Time":"2018-02-14T15:44:20Z"}
-- buggy/buggy_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package buggy

import "testing"

func Test(t *testing.T) {
	t.Fatal("buggy!")
}
-- go.mod --
module "rsc.io/quote"

require "rsc.io/sampler" v1.3.0
-- quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package quote collects pithy sayings.
package quote // import "rsc.io/quote"

import "rsc.io/sampler"

// Hello returns a greeting.
func Hello() string {
	return sampler.Hello()
}

// Glass returns a useful phrase for world travelers.
func Glass() string {
	// See http://www.oocities.org/nodotus/hbglass.html.
	return "I can eat glass and it doesn't hurt me."
}

// Go returns a Go proverb.
func Go() string {
	return "Don't communicate by sharing memory, share memory by communicating."
}

// Opt returns an optimization truth.
func Opt() string {
	// Wisdom from ken.
	return "If a program is too slow, it must have a loop."
}
-- quote_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package quote

import (
	"os"
	"testing"
)

func init() {
	os.Setenv("LC_ALL", "en")
}

func TestHello(t *testing.T) {
	hello := "Hello, world."
	if out := Hello(); out != hello {
		t.Errorf("Hello() = %q, want %q", out, hello)
	}
}

func TestGlass(t *testing.T) {
	glass := "I can eat glass and it doesn't hurt me."
	if out := Glass(); out != glass {
		t.Errorf("Glass() = %q, want %q", out, glass)
	}
}

func TestGo(t *testing.T) {
	go1 := "Don't communicate by sharing memory, share memory by communicating."
	if out := Go(); out != go1 {
		t.Errorf("Go() = %q, want %q", out, go1)
	}
}

func TestOpt(t *testing.T) {
	opt := "If a program is too slow, it must have a loop."
	if out := Opt(); out != opt {
		t.Errorf("Opt() = %q, want %q", out, opt)
	}
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_quote_v2_v2.0.1.txt
================================================
rsc.io/quote/v2@v2.0.1

-- .mod --
module rsc.io/quote/v2

require rsc.io/sampler v1.3.0
-- .info --
{"Version":"v2.0.1","Name":"754f68430672776c84704e2d10209a6ec700cd64","Short":"754f68430672","Time":"2018-07-09T16:25:34Z"}
-- go.mod --
module rsc.io/quote/v2

require rsc.io/sampler v1.3.0
-- quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package quote collects pithy sayings.
package quote // import "rsc.io/quote"

import "rsc.io/sampler"

// Hello returns a greeting.
func HelloV2() string {
	return sampler.Hello()
}

// Glass returns a useful phrase for world travelers.
func GlassV2() string {
	// See http://www.oocities.org/nodotus/hbglass.html.
	return "I can eat glass and it doesn't hurt me."
}

// Go returns a Go proverb.
func GoV2() string {
	return "Don't communicate by sharing memory, share memory by communicating."
}

// Opt returns an optimization truth.
func OptV2() string {
	// Wisdom from ken.
	return "If a program is too slow, it must have a loop."
}
-- quote_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package quote

import (
	"os"
	"testing"
)

func init() {
	os.Setenv("LC_ALL", "en")
}

func TestHello(t *testing.T) {
	hello := "Hello, world."
	if out := Hello(); out != hello {
		t.Errorf("Hello() = %q, want %q", out, hello)
	}
}

func TestGlass(t *testing.T) {
	glass := "I can eat glass and it doesn't hurt me."
	if out := Glass(); out != glass {
		t.Errorf("Glass() = %q, want %q", out, glass)
	}
}

func TestGo(t *testing.T) {
	go1 := "Don't communicate by sharing memory, share memory by communicating."
	if out := Go(); out != go1 {
		t.Errorf("Go() = %q, want %q", out, go1)
	}
}

func TestOpt(t *testing.T) {
	opt := "If a program is too slow, it must have a loop."
	if out := Opt(); out != opt {
		t.Errorf("Opt() = %q, want %q", out, opt)
	}
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_quote_v3_v3.0.0.txt
================================================
rsc.io/quote/v3@v3.0.0

-- .mod --
module rsc.io/quote/v3

require rsc.io/sampler v1.3.0

-- .info --
{"Version":"v3.0.0","Name":"d88915d7e77ed0fd35d0a022a2f244e2202fd8c8","Short":"d88915d7e77e","Time":"2018-07-09T15:34:46Z"}
-- go.mod --
module rsc.io/quote/v3

require rsc.io/sampler v1.3.0

-- quote.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package quote collects pithy sayings.
package quote // import "rsc.io/quote"

import "rsc.io/sampler"

// Hello returns a greeting.
func HelloV3() string {
	return sampler.Hello()
}

// Glass returns a useful phrase for world travelers.
func GlassV3() string {
	// See http://www.oocities.org/nodotus/hbglass.html.
	return "I can eat glass and it doesn't hurt me."
}

// Go returns a Go proverb.
func GoV3() string {
	return "Don't communicate by sharing memory, share memory by communicating."
}

// Opt returns an optimization truth.
func OptV3() string {
	// Wisdom from ken.
	return "If a program is too slow, it must have a loop."
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_sampler_v1.3.0.txt
================================================
rsc.io/sampler@v1.3.0

-- .mod --
module "rsc.io/sampler"

require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
-- .info --
{"Version":"v1.3.0","Name":"0cc034b51e57ed7832d4c67d526f75a900996e5c","Short":"0cc034b51e57","Time":"2018-02-13T19:05:03Z"}
-- glass.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Translations from Frank da Cruz, Ethan Mollick, and many others.
// See http://kermitproject.org/utf8.html.
// http://www.oocities.org/nodotus/hbglass.html
// https://en.wikipedia.org/wiki/I_Can_Eat_Glass

package sampler

var glass = newText(`

English: en: I can eat glass and it doesn't hurt me.
French: fr: Je peux manger du verre, ça ne me fait pas mal.
Spanish: es: Puedo comer vidrio, no me hace daño.

`)
-- glass_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sampler

import (
	"testing"

	"golang.org/x/text/language"
	_ "rsc.io/testonly"
)

var glassTests = []struct {
	prefs []language.Tag
	text  string
}{
	{
		[]language.Tag{language.Make("en-US"), language.Make("fr")},
		"I can eat glass and it doesn't hurt me.",
	},
	{
		[]language.Tag{language.Make("fr"), language.Make("en-US")},
		"Je peux manger du verre, ça ne me fait pas mal.",
	},
}

func TestGlass(t *testing.T) {
	for _, tt := range glassTests {
		text := Glass(tt.prefs...)
		if text != tt.text {
			t.Errorf("Glass(%v) = %q, want %q", tt.prefs, text, tt.text)
		}
	}
}
-- go.mod --
module "rsc.io/sampler"

require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
-- hello.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Translations by Google Translate.

package sampler

var hello = newText(`

English: en: Hello, world.
French: fr: Bonjour le monde.
Spanish: es: Hola Mundo.

`)
-- hello_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sampler

import (
	"testing"

	"golang.org/x/text/language"
)

var helloTests = []struct {
	prefs []language.Tag
	text  string
}{
	{
		[]language.Tag{language.Make("en-US"), language.Make("fr")},
		"Hello, world.",
	},
	{
		[]language.Tag{language.Make("fr"), language.Make("en-US")},
		"Bonjour le monde.",
	},
}

func TestHello(t *testing.T) {
	for _, tt := range helloTests {
		text := Hello(tt.prefs...)
		if text != tt.text {
			t.Errorf("Hello(%v) = %q, want %q", tt.prefs, text, tt.text)
		}
	}
}
-- sampler.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sampler shows simple texts.
package sampler // import "rsc.io/sampler"

import (
	"os"
	"strings"

	"golang.org/x/text/language"
)

// DefaultUserPrefs returns the default user language preferences.
// It consults the $LC_ALL, $LC_MESSAGES, and $LANG environment
// variables, in that order.
func DefaultUserPrefs() []language.Tag {
	var prefs []language.Tag
	for _, k := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
		if env := os.Getenv(k); env != "" {
			prefs = append(prefs, language.Make(env))
		}
	}
	return prefs
}

// Hello returns a localized greeting.
// If no prefs are given, Hello uses DefaultUserPrefs.
func Hello(prefs ...language.Tag) string {
	if len(prefs) == 0 {
		prefs = DefaultUserPrefs()
	}
	return hello.find(prefs)
}

// Glass returns a localized silly phrase.
// If no prefs are given, Glass uses DefaultUserPrefs.
func Glass(prefs ...language.Tag) string {
	if len(prefs) == 0 {
		prefs = DefaultUserPrefs()
	}
	return glass.find(prefs)
}

// A text is a localized text.
type text struct {
	byTag   map[string]string
	matcher language.Matcher
}

// newText creates a new localized text, given a list of translations.
func newText(s string) *text {
	t := &text{
		byTag: make(map[string]string),
	}
	var tags []language.Tag
	for _, line := range strings.Split(s, "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		f := strings.Split(line, ": ")
		if len(f) != 3 {
			continue
		}
		tag := language.Make(f[1])
		tags = append(tags, tag)
		t.byTag[tag.String()] = f[2]
	}
	t.matcher = language.NewMatcher(tags)
	return t
}

// find finds the text to use for the given language tag preferences.
func (t *text) find(prefs []language.Tag) string {
	tag, _, _ := t.matcher.Match(prefs...)
	s := t.byTag[tag.String()]
	if strings.HasPrefix(s, "RTL ") {
		s = "\u200F" + strings.TrimPrefix(s, "RTL ") + "\u200E"
	}
	return s
}


================================================
FILE: internal/imports/testdata/mod/rsc.io_sampler_v1.3.1.txt
================================================
rsc.io/sampler@v1.3.1

-- .mod --
module "rsc.io/sampler"

require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
-- .info --
{"Version":"v1.3.1","Name":"f545d0289d06e2add4556ea6a15fc4938014bf87","Short":"f545d0289d06","Time":"2018-02-14T16:34:12Z"}
-- glass.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Translations from Frank da Cruz, Ethan Mollick, and many others.
// See http://kermitproject.org/utf8.html.
// http://www.oocities.org/nodotus/hbglass.html
// https://en.wikipedia.org/wiki/I_Can_Eat_Glass

package sampler

var glass = newText(`

English: en: I can eat glass and it doesn't hurt me.
French: fr: Je peux manger du verre, ça ne me fait pas mal.
Spanish: es: Puedo comer vidrio, no me hace daño.

`)
-- glass_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sampler

import (
	"testing"

	"golang.org/x/text/language"
)

var glassTests = []struct {
	prefs []language.Tag
	text  string
}{
	{
		[]language.Tag{language.Make("en-US"), language.Make("fr")},
		"I can eat glass and it doesn't hurt me.",
	},
	{
		[]language.Tag{language.Make("fr"), language.Make("en-US")},
		"Je peux manger du verre, ça ne me fait pas mal.",
	},
}

func TestGlass(t *testing.T) {
	for _, tt := range glassTests {
		text := Glass(tt.prefs...)
		if text != tt.text {
			t.Errorf("Glass(%v) = %q, want %q", tt.prefs, text, tt.text)
		}
	}
}
-- go.mod --
module "rsc.io/sampler"

require "golang.org/x/text" v0.0.0-20170915032832-14c0d48ead0c
-- hello.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Translations by Google Translate.

package sampler

var hello = newText(`

English: en: Hello, world.
French: fr: Bonjour le monde.
Spanish: es: Hola Mundo.

`)
-- hello_test.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package sampler

import (
	"testing"

	"golang.org/x/text/language"
)

var helloTests = []struct {
	prefs []language.Tag
	text  string
}{
	{
		[]language.Tag{language.Make("en-US"), language.Make("fr")},
		"Hello, world.",
	},
	{
		[]language.Tag{language.Make("fr"), language.Make("en-US")},
		"Bonjour le monde.",
	},
}

func TestHello(t *testing.T) {
	for _, tt := range helloTests {
		text := Hello(tt.prefs...)
		if text != tt.text {
			t.Errorf("Hello(%v) = %q, want %q", tt.prefs, text, tt.text)
		}
	}
}
-- sampler.go --
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package sampler shows simple texts in a variety of languages.
package sampler // import "rsc.io/sampler"

import (
	"os"
	"strings"

	"golang.org/x/text/language"
)

// DefaultUserPrefs returns the default user language preferences.
// It consults the $LC_ALL, $LC_MESSAGES, and $LANG environment
// variables, in that order.
func DefaultUserPrefs() []language.Tag {
	var prefs []language.Tag
	for _, k := range []string{"LC_ALL", "LC_MESSAGES", "LANG"} {
		if env := os.Getenv(k); env != "" {
			prefs = append(prefs, language.Make(env))
		}
	}
	return prefs
}

// Hello returns a localized greeting.
// If no prefs are given, Hello uses DefaultUserPrefs.
func Hello(prefs ...language.Tag) string {
	if len(prefs) == 0 {
		prefs = DefaultUserPrefs()
	}
	return hello.find(prefs)
}

// Glass returns a localized silly phrase.
// If no prefs are given, Glass uses DefaultUserPrefs.
func Glass(prefs ...language.Tag) string {
	if len(prefs) == 0 {
		prefs = DefaultUserPrefs()
	}
	return glass.find(prefs)
}

// A text is a localized text.
type text struct {
	byTag   map[string]string
	matcher language.Matcher
}

// newText creates a new localized text, given a list of translations.
func newText(s string) *text {
	t := &text{
		byTag: make(map[string]string),
	}
	var tags []language.Tag
	for _, line := range strings.Split(s, "\n") {
		line = strings.TrimSpace(line)
		if line == "" {
			continue
		}
		f := strings.Split(line, ": ")
		if len(f) != 3 {
			continue
		}
		tag := language.Make(f[1])
		tags = append(tags, tag)
		t.byTag[tag.String()] = f[2]
	}
	t.matcher = language.NewMatcher(tags)
	return t
}

// find finds the text to use for the given language tag preferences.
func (t *text) find(prefs []language.Tag) string {
	tag, _, _ := t.matcher.Match(prefs...)
	s := t.byTag[tag.String()]
	if strings.HasPrefix(s, "RTL ") {
		s = "\u200F" + strings.TrimPrefix(s, "RTL ") + "\u200E"
	}
	return s
}


================================================
FILE: internal/jsonrpc2/conn.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"sync"
	"sync/atomic"
	"time"

	"golang.org/x/tools/internal/event"
	"golang.org/x/tools/internal/event/label"
)

// Conn is the common interface to jsonrpc clients and servers.
// Conn is bidirectional; it does not have a designated server or client end.
// It manages the jsonrpc2 protocol, connecting responses back to their calls.
type Conn interface {
	// Call invokes the target method and waits for a response.
	// The params will be marshaled to JSON before sending over the wire, and will
	// be handed to the method invoked.
	// The response will be unmarshaled from JSON into the result.
	// The id returned will be unique from this connection, and can be used for
	// logging or tracking.
	Call(ctx context.Context, method string, params, result any) (ID, error)

	// Notify invokes the target method but does not wait for a response.
	// The params will be marshaled to JSON before sending over the wire, and will
	// be handed to the method invoked.
	Notify(ctx context.Context, method string, params any) error

	// Go starts a goroutine to handle the connection.
	// It must be called exactly once for each Conn.
	// It returns immediately.
	// You must block on Done() to wait for the connection to shut down.
	// This is a temporary measure, this should be started automatically in the
	// future.
	Go(ctx context.Context, handler Handler)

	// Close closes the connection and it's underlying stream.
	// It does not wait for the close to complete, use the Done() channel for
	// that.
	Close() error

	// Done returns a channel that will be closed when the processing goroutine
	// has terminated, which will happen if Close() is called or an underlying
	// stream is closed.
	Done() <-chan struct{}

	// Err returns an error if there was one from within the processing goroutine.
	// If err returns non nil, the connection will be already closed or closing.
	Err() error
}

type conn struct {
	seq       int64      // must only be accessed using atomic operations
	writeMu   sync.Mutex // protects writes to the stream
	stream    Stream
	pendingMu sync.Mutex // protects the pending map
	pending   map[ID]chan *Response

	done chan struct{}
	err  atomic.Value
}

// NewConn creates a new connection object around the supplied stream.
func NewConn(s Stream) Conn {
	conn := &conn{
		stream:  s,
		pending: make(map[ID]chan *Response),
		done:    make(chan struct{}),
	}
	return conn
}

func (c *conn) Notify(ctx context.Context, method string, params any) (err error) {
	notify, err := NewNotification(method, params)
	if err != nil {
		return fmt.Errorf("marshaling notify parameters: %v", err)
	}
	ctx, done := event.Start(ctx, method,
		Method.Of(method),
		RPCDirection.Of(Outbound),
	)
	start := time.Now()
	defer func() {
		ctx = recordStatus(ctx, err)
		event.Metric(ctx, Latency.Of(time.Since(start).Seconds()))
		done()
	}()

	event.Metric(ctx, Started.Of(1))
	n, err := c.write(ctx, notify)
	event.Metric(ctx, SentBytes.Of64(n))
	return err
}

func (c *conn) Call(ctx context.Context, method string, params, result any) (_ ID, err error) {
	// generate a new request identifier
	id := ID{number: atomic.AddInt64(&c.seq, 1)}
	call, err := NewCall(id, method, params)
	if err != nil {
		return id, fmt.Errorf("marshaling call parameters: %v", err)
	}
	ctx, done := event.Start(ctx, method,
		Method.Of(method),
		RPCDirection.Of(Outbound),
		RPCID.Of(fmt.Sprintf("%q", id)),
	)
	start := time.Now()
	var rpcErr error
	defer func() {
		ctx = recordStatus(ctx, rpcErr)
		event.Metric(ctx, Latency.Of(time.Since(start).Seconds()))
		done()
	}()
	event.Metric(ctx, Started.Of(1))
	// We have to add ourselves to the pending map before we send, otherwise we
	// are racing the response. Also add a buffer to rchan, so that if we get a
	// wire response between the time this call is cancelled and id is deleted
	// from c.pending, the send to rchan will not block.
	rchan := make(chan *Response, 1)
	c.pendingMu.Lock()
	c.pending[id] = rchan
	c.pendingMu.Unlock()
	defer func() {
		c.pendingMu.Lock()
		delete(c.pending, id)
		c.pendingMu.Unlock()
	}()
	// now we are ready to send
	n, err := c.write(ctx, call)
	event.Metric(ctx, SentBytes.Of64(n))
	if err != nil {
		// sending failed, we will never get a response, so don't leave it pending
		return id, err
	}
	// now wait for the response
	select {
	case response := <-rchan:
		// is it an error response?
		if response.err != nil {
			rpcErr = response.err
			return id, response.err
		}
		if result == nil || len(response.result) == 0 {
			return id, nil
		}
		if err := json.Unmarshal(response.result, result); err != nil {
			return id, fmt.Errorf("unmarshaling result: %v", err)
		}
		return id, nil
	case <-ctx.Done():
		rpcErr = ctx.Err()
		return id, ctx.Err()
	}
}

func (c *conn) replier(req Request, start time.Time, spanDone func()) Replier {
	return func(ctx context.Context, result any, err error) error {
		// Save the RPC error before err gets reassigned by NewResponse/write below.
		rpcErr := err
		defer func() {
			ctx = recordStatus(ctx, rpcErr)
			event.Metric(ctx, Latency.Of(time.Since(start).Seconds()))
			spanDone()
		}()
		call, ok := req.(*Call)
		if !ok {
			// request was a notify, no need to respond
			return nil
		}
		response, err := NewResponse(call.id, result, err)
		if err != nil {
			return err
		}
		n, err := c.write(ctx, response)
		event.Metric(ctx, SentBytes.Of64(n))
		if err != nil {
			// TODO(iancottrell): if a stream write fails, we really need to shut down
			// the whole stream
			return err
		}
		return nil
	}
}

func (c *conn) write(ctx context.Context, msg Message) (int64, error) {
	c.writeMu.Lock()
	defer c.writeMu.Unlock()
	return c.stream.Write(ctx, msg)
}

func (c *conn) Go(ctx context.Context, handler Handler) {
	go c.run(ctx, handler)
}

func (c *conn) run(ctx context.Context, handler Handler) {
	defer close(c.done)
	for {
		// get the next message
		msg, n, err := c.stream.Read(ctx)
		if err != nil {
			// The stream failed, we cannot continue.
			c.fail(err)
			return
		}
		switch msg := msg.(type) {
		case Request:
			labels := []label.Label{
				Method.Of(msg.Method()),
				RPCDirection.Of(Inbound),
				{}, // reserved for ID if present
			}
			if call, ok := msg.(*Call); ok {
				labels[len(labels)-1] = RPCID.Of(fmt.Sprintf("%q", call.ID()))
			} else {
				labels = labels[:len(labels)-1]
			}
			reqCtx, spanDone := event.Start(ctx, msg.Method(), labels...)
			start := time.Now()
			event.Metric(reqCtx,
				Started.Of(1),
				ReceivedBytes.Of64(n))
			if err := handler(reqCtx, c.replier(msg, start, spanDone), msg); err != nil {
				// delivery failed, not much we can do
				event.Error(reqCtx, "jsonrpc2 message delivery failed", err)
			}
		case *Response:
			// If method is not set, this should be a response, in which case we must
			// have an id to send the response back to the caller.
			c.pendingMu.Lock()
			rchan, ok := c.pending[msg.id]
			c.pendingMu.Unlock()
			if ok {
				rchan <- msg
			}
		}
	}
}

func (c *conn) Close() error {
	return c.stream.Close()
}

func (c *conn) Done() <-chan struct{} {
	return c.done
}

func (c *conn) Err() error {
	if err := c.err.Load(); err != nil {
		return err.(error)
	}
	return nil
}

// fail sets a failure condition on the stream and closes it.
func (c *conn) fail(err error) {
	c.err.Store(err)
	c.stream.Close()
}

func recordStatus(ctx context.Context, err error) context.Context {
	var status string
	var wireError *WireError
	switch {
	case err == nil:
		status = "OK"
	case errors.Is(err, context.Canceled):
		status = "CANCELED"
	case errors.As(err, &wireError) && wireError.Code == -32800: // JSON RPC request canceled
		status = "CANCELED"
	case errors.Is(err, context.DeadlineExceeded):
		status = "DEADLINE_EXCEEDED"
	case errors.Is(err, ErrMethodNotFound):
		status = "METHOD_NOT_FOUND"
	default:
		status = "ERROR"
	}
	return event.Label(ctx, StatusCode.Of(status))
}


================================================
FILE: internal/jsonrpc2/handler.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"fmt"
	"sync"

	"golang.org/x/tools/internal/event"
)

// Handler is invoked to handle incoming requests.
// The Replier sends a reply to the request and must be called exactly once.
type Handler func(ctx context.Context, reply Replier, req Request) error

// Replier is passed to handlers to allow them to reply to the request.
// If err is set then result will be ignored.
type Replier func(ctx context.Context, result any, err error) error

// MethodNotFound is a Handler that replies to all call requests with the
// standard method not found response.
// This should normally be the final handler in a chain.
func MethodNotFound(ctx context.Context, reply Replier, req Request) error {
	return reply(ctx, nil, fmt.Errorf("%w: %q", ErrMethodNotFound, req.Method()))
}

// MustReplyHandler is a middleware that creates a Handler that panics if the
// wrapped handler does not call Reply for every request that it is passed.
func MustReplyHandler(handler Handler) Handler {
	return func(ctx context.Context, reply Replier, req Request) error {
		called := false
		err := handler(ctx, func(ctx context.Context, result any, err error) error {
			if called {
				panic(fmt.Errorf("request %q replied to more than once", req.Method()))
			}
			called = true
			return reply(ctx, result, err)
		}, req)
		if !called {
			panic(fmt.Errorf("request %q was never replied to", req.Method()))
		}
		return err
	}
}

// CancelHandler returns a handler that supports cancellation, and a function
// that can be used to trigger canceling in progress requests.
func CancelHandler(handler Handler) (Handler, func(id ID)) {
	var mu sync.Mutex
	handling := make(map[ID]context.CancelFunc)
	wrapped := func(ctx context.Context, reply Replier, req Request) error {
		if call, ok := req.(*Call); ok {
			cancelCtx, cancel := context.WithCancel(ctx)
			ctx = cancelCtx
			mu.Lock()
			handling[call.ID()] = cancel
			mu.Unlock()
			innerReply := reply
			reply = func(ctx context.Context, result any, err error) error {
				mu.Lock()
				delete(handling, call.ID())
				mu.Unlock()
				return innerReply(ctx, result, err)
			}
		}
		return handler(ctx, reply, req)
	}
	return wrapped, func(id ID) {
		mu.Lock()
		cancel, found := handling[id]
		mu.Unlock()
		if found {
			cancel()
		}
	}
}

// AsyncHandler is a middleware that returns a handler that processes each
// request goes in its own goroutine.
// The handler returns immediately, without the request being processed.
// Each request then waits for the previous request to finish before it starts.
// This allows the stream to unblock at the cost of unbounded goroutines
// all stalled on the previous one.
func AsyncHandler(handler Handler) Handler {
	nextRequest := make(chan struct{})
	close(nextRequest)
	return func(ctx context.Context, reply Replier, req Request) error {
		waitForPrevious := nextRequest
		nextRequest = make(chan struct{})
		releaser := &releaser{ch: nextRequest}
		innerReply := reply
		reply = func(ctx context.Context, result any, err error) error {
			releaser.release(true)
			return innerReply(ctx, result, err)
		}
		_, queueDone := event.Start(ctx, "queued")
		ctx = context.WithValue(ctx, asyncKey, releaser)
		go func() {
			<-waitForPrevious
			queueDone()
			if err := handler(ctx, reply, req); err != nil {
				event.Error(ctx, "jsonrpc2 async message delivery failed", err)
			}
		}()
		return nil
	}
}

// Async, when used with the [AsyncHandler] middleware, indicates that the
// current jsonrpc2 request may be handled asynchronously to subsequent
// requests.
//
// When not used with an AsyncHandler, Async is a no-op.
//
// Async must be called at most once on each request's context (and its
// descendants).
func Async(ctx context.Context) {
	if r, ok := ctx.Value(asyncKey).(*releaser); ok {
		r.release(false)
	}
}

type asyncKeyType struct{}

var asyncKey = asyncKeyType{}

// A releaser implements concurrency safe 'releasing' of async requests. (A
// request is released when it is allowed to run concurrent with other
// requests, via a call to [Async].)
type releaser struct {
	mu       sync.Mutex
	ch       chan struct{}
	released bool
}

// release closes the associated channel. If soft is set, multiple calls to
// release are allowed.
func (r *releaser) release(soft bool) {
	r.mu.Lock()
	defer r.mu.Unlock()

	if r.released {
		if !soft {
			panic("jsonrpc2.Async called multiple times")
		}
	} else {
		close(r.ch)
		r.released = true
	}
}


================================================
FILE: internal/jsonrpc2/jsonrpc2.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package jsonrpc2 is a minimal implementation of the JSON RPC 2 spec.
// https://www.jsonrpc.org/specification
// It is intended to be compatible with other implementations at the wire level.
package jsonrpc2

const (
	// ErrIdleTimeout is returned when serving timed out waiting for new connections.
	ErrIdleTimeout = constError("timed out waiting for new connections")
)

type constError string

func (e constError) Error() string { return string(e) }


================================================
FILE: internal/jsonrpc2/jsonrpc2_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2_test

import (
	"context"
	"encoding/json"
	"flag"
	"fmt"
	"net"
	"path"
	"reflect"
	"testing"

	"golang.org/x/tools/internal/event/export/eventtest"
	"golang.org/x/tools/internal/jsonrpc2"
	"golang.org/x/tools/internal/jsonrpc2/stack/stacktest"
)

var logRPC = flag.Bool("logrpc", false, "Enable jsonrpc2 communication logging")

type callTest struct {
	method string
	params any
	expect any
}

var callTests = []callTest{
	{"no_args", nil, true},
	{"one_string", "fish", "got:fish"},
	{"one_number", 10, "got:10"},
	{"join", []string{"a", "b", "c"}, "a/b/c"},
	//TODO: expand the test cases
}

func (test *callTest) newResults() any {
	switch e := test.expect.(type) {
	case []any:
		var r []any
		for _, v := range e {
			r = append(r, reflect.New(reflect.TypeOf(v)).Interface())
		}
		return r
	case nil:
		return nil
	default:
		return reflect.New(reflect.TypeOf(test.expect)).Interface()
	}
}

func (test *callTest) verifyResults(t *testing.T, results any) {
	if results == nil {
		return
	}
	val := reflect.Indirect(reflect.ValueOf(results)).Interface()
	if !reflect.DeepEqual(val, test.expect) {
		t.Errorf("%v:Results are incorrect, got %+v expect %+v", test.method, val, test.expect)
	}
}

func TestCall(t *testing.T) {
	stacktest.NoLeak(t)
	ctx := eventtest.NewContext(context.Background(), t)
	for _, headers := range []bool{false, true} {
		name := "Plain"
		if headers {
			name = "Headers"
		}
		t.Run(name, func(t *testing.T) {
			ctx := eventtest.NewContext(ctx, t)
			a, b, done := prepare(ctx, headers)
			defer done()
			for _, test := range callTests {
				t.Run(test.method, func(t *testing.T) {
					ctx := eventtest.NewContext(ctx, t)
					results := test.newResults()
					if _, err := a.Call(ctx, test.method, test.params, results); err != nil {
						t.Fatalf("%v:Call failed: %v", test.method, err)
					}
					test.verifyResults(t, results)
					if _, err := b.Call(ctx, test.method, test.params, results); err != nil {
						t.Fatalf("%v:Call failed: %v", test.method, err)
					}
					test.verifyResults(t, results)
				})
			}
		})
	}
}

func prepare(ctx context.Context, withHeaders bool) (jsonrpc2.Conn, jsonrpc2.Conn, func()) {
	// make a wait group that can be used to wait for the system to shut down
	aPipe, bPipe := net.Pipe()
	a := run(ctx, withHeaders, aPipe)
	b := run(ctx, withHeaders, bPipe)
	return a, b, func() {
		a.Close()
		b.Close()
		<-a.Done()
		<-b.Done()
	}
}

func run(ctx context.Context, withHeaders bool, nc net.Conn) jsonrpc2.Conn {
	var stream jsonrpc2.Stream
	if withHeaders {
		stream = jsonrpc2.NewHeaderStream(nc)
	} else {
		stream = jsonrpc2.NewRawStream(nc)
	}
	conn := jsonrpc2.NewConn(stream)
	conn.Go(ctx, testHandler())
	return conn
}

func testHandler() jsonrpc2.Handler {
	return func(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
		switch req.Method() {
		case "no_args":
			if len(req.Params()) > 0 {
				return reply(ctx, nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams))
			}
			return reply(ctx, true, nil)
		case "one_string":
			var v string
			if err := json.Unmarshal(req.Params(), &v); err != nil {
				return reply(ctx, nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err))
			}
			return reply(ctx, "got:"+v, nil)
		case "one_number":
			var v int
			if err := json.Unmarshal(req.Params(), &v); err != nil {
				return reply(ctx, nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err))
			}
			return reply(ctx, fmt.Sprintf("got:%d", v), nil)
		case "join":
			var v []string
			if err := json.Unmarshal(req.Params(), &v); err != nil {
				return reply(ctx, nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err))
			}
			return reply(ctx, path.Join(v...), nil)
		default:
			return jsonrpc2.MethodNotFound(ctx, reply, req)
		}
	}
}


================================================
FILE: internal/jsonrpc2/labels.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import "golang.org/x/tools/internal/event/keys"

// These keys are used for creating labels to instrument jsonrpc2 events.
var (
	Method        = keys.NewString("method", "")
	RPCID         = keys.NewString("id", "")
	RPCDirection  = keys.NewString("direction", "")
	Started       = keys.NewInt("started", "count of started RPCs")
	SentBytes     = keys.NewInt("sent_bytes", "bytes sent")
	ReceivedBytes = keys.NewInt("received_bytes", "bytes received")
	StatusCode    = keys.NewString("status.code", "")
	Latency       = keys.NewFloat("latency", "elapsed time in seconds")
)

const (
	Inbound  = "in"
	Outbound = "out"
)


================================================
FILE: internal/jsonrpc2/messages.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"encoding/json"
	"errors"
	"fmt"
)

// Message is the interface to all jsonrpc2 message types.
// They share no common functionality, but are a closed set of concrete types
// that are allowed to implement this interface. The message types are *Call,
// *Notification and *Response.
type Message interface {
	// isJSONRPC2Message is used to make the set of message implementations a
	// closed set.
	isJSONRPC2Message()
}

// Request is the shared interface to jsonrpc2 messages that request
// a method be invoked.
// The request types are a closed set of *Call and *Notification.
type Request interface {
	Message
	// Method is a string containing the method name to invoke.
	Method() string
	// Params is a JSON value (object, array, null, or "") with the parameters of the method.
	Params() json.RawMessage
	// isJSONRPC2Request is used to make the set of request implementations closed.
	isJSONRPC2Request()
}

// Notification is a request for which a response cannot occur, and as such
// it has not ID.
type Notification struct {
	// Method is a string containing the method name to invoke.
	method string
	params json.RawMessage
}

// Call is a request that expects a response.
// The response will have a matching ID.
type Call struct {
	// Method is a string containing the method name to invoke.
	method string
	// Params is a JSON value (object, array, null, or "") with the parameters of the method.
	params json.RawMessage
	// id of this request, used to tie the Response back to the request.
	id ID
}

// Response is a reply to a Call.
// It will have the same ID as the call it is a response to.
type Response struct {
	// result is the content of the response.
	result json.RawMessage
	// err is set only if the call failed.
	err error
	// ID of the request this is a response to.
	id ID
}

// NewNotification constructs a new Notification message for the supplied
// method and parameters.
func NewNotification(method string, params any) (*Notification, error) {
	p, merr := marshalToRaw(params)
	return &Notification{method: method, params: p}, merr
}

func (msg *Notification) Method() string          { return msg.method }
func (msg *Notification) Params() json.RawMessage { return msg.params }
func (msg *Notification) isJSONRPC2Message()      {}
func (msg *Notification) isJSONRPC2Request()      {}

func (n *Notification) MarshalJSON() ([]byte, error) {
	msg := wireRequest{Method: n.method, Params: &n.params}
	data, err := json.Marshal(msg)
	if err != nil {
		return data, fmt.Errorf("marshaling notification: %w", err)
	}
	return data, nil
}

func (n *Notification) UnmarshalJSON(data []byte) error {
	msg := wireRequest{}
	if err := json.Unmarshal(data, &msg); err != nil {
		return fmt.Errorf("unmarshaling notification: %w", err)
	}
	n.method = msg.Method
	if msg.Params != nil {
		n.params = *msg.Params
	}
	return nil
}

// NewCall constructs a new Call message for the supplied ID, method and
// parameters.
func NewCall(id ID, method string, params any) (*Call, error) {
	p, merr := marshalToRaw(params)
	return &Call{id: id, method: method, params: p}, merr
}

func (msg *Call) Method() string          { return msg.method }
func (msg *Call) Params() json.RawMessage { return msg.params }
func (msg *Call) ID() ID                  { return msg.id }
func (msg *Call) isJSONRPC2Message()      {}
func (msg *Call) isJSONRPC2Request()      {}

func (c *Call) MarshalJSON() ([]byte, error) {
	msg := wireRequest{Method: c.method, Params: &c.params, ID: &c.id}
	data, err := json.Marshal(msg)
	if err != nil {
		return data, fmt.Errorf("marshaling call: %w", err)
	}
	return data, nil
}

func (c *Call) UnmarshalJSON(data []byte) error {
	msg := wireRequest{}
	if err := json.Unmarshal(data, &msg); err != nil {
		return fmt.Errorf("unmarshaling call: %w", err)
	}
	c.method = msg.Method
	if msg.Params != nil {
		c.params = *msg.Params
	}
	if msg.ID != nil {
		c.id = *msg.ID
	}
	return nil
}

// NewResponse constructs a new Response message that is a reply to the
// supplied. If err is set result may be ignored.
func NewResponse(id ID, result any, err error) (*Response, error) {
	r, merr := marshalToRaw(result)
	return &Response{id: id, result: r, err: err}, merr
}

func (msg *Response) ID() ID                  { return msg.id }
func (msg *Response) Result() json.RawMessage { return msg.result }
func (msg *Response) Err() error              { return msg.err }
func (msg *Response) isJSONRPC2Message()      {}

func (r *Response) MarshalJSON() ([]byte, error) {
	msg := &wireResponse{Error: toWireError(r.err), ID: &r.id}
	if msg.Error == nil {
		msg.Result = &r.result
	}
	data, err := json.Marshal(msg)
	if err != nil {
		return data, fmt.Errorf("marshaling notification: %w", err)
	}
	return data, nil
}

func toWireError(err error) *WireError {
	if err == nil {
		// no error, the response is complete
		return nil
	}
	if err, ok := err.(*WireError); ok {
		// already a wire error, just use it
		return err
	}
	result := &WireError{Message: err.Error()}
	var wrapped *WireError
	if errors.As(err, &wrapped) {
		// if we wrapped a wire error, keep the code from the wrapped error
		// but the message from the outer error
		result.Code = wrapped.Code
	}
	return result
}

func (r *Response) UnmarshalJSON(data []byte) error {
	msg := wireResponse{}
	if err := json.Unmarshal(data, &msg); err != nil {
		return fmt.Errorf("unmarshaling jsonrpc response: %w", err)
	}
	if msg.Result != nil {
		r.result = *msg.Result
	}
	if msg.Error != nil {
		r.err = msg.Error
	}
	if msg.ID != nil {
		r.id = *msg.ID
	}
	return nil
}

func DecodeMessage(data []byte) (Message, error) {
	msg := wireCombined{}
	if err := json.Unmarshal(data, &msg); err != nil {
		return nil, fmt.Errorf("unmarshaling jsonrpc message: %w", err)
	}
	if msg.Method == "" {
		// no method, should be a response
		if msg.ID == nil {
			return nil, ErrInvalidRequest
		}
		response := &Response{id: *msg.ID}
		if msg.Error != nil {
			response.err = msg.Error
		}
		if msg.Result != nil {
			response.result = *msg.Result
		}
		return response, nil
	}
	// has a method, must be a request
	if msg.ID == nil {
		// request with no ID is a notify
		notify := &Notification{method: msg.Method}
		if msg.Params != nil {
			notify.params = *msg.Params
		}
		return notify, nil
	}
	// request with an ID, must be a call
	call := &Call{method: msg.Method, id: *msg.ID}
	if msg.Params != nil {
		call.params = *msg.Params
	}
	return call, nil
}

func marshalToRaw(obj any) (json.RawMessage, error) {
	data, err := json.Marshal(obj)
	if err != nil {
		return json.RawMessage{}, err
	}
	return json.RawMessage(data), nil
}


================================================
FILE: internal/jsonrpc2/serve.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"errors"
	"io"
	"math"
	"net"
	"os"
	"time"

	"golang.org/x/tools/internal/event"
)

// NOTE: This file provides an experimental API for serving multiple remote
// jsonrpc2 clients over the network. For now, it is intentionally similar to
// net/http, but that may change in the future as we figure out the correct
// semantics.

// A StreamServer is used to serve incoming jsonrpc2 clients communicating over
// a newly created connection.
type StreamServer interface {
	ServeStream(context.Context, Conn) error
}

// The ServerFunc type is an adapter that implements the StreamServer interface
// using an ordinary function.
type ServerFunc func(context.Context, Conn) error

// ServeStream calls f(ctx, s).
func (f ServerFunc) ServeStream(ctx context.Context, c Conn) error {
	return f(ctx, c)
}

// HandlerServer returns a StreamServer that handles incoming streams using the
// provided handler.
func HandlerServer(h Handler) StreamServer {
	return ServerFunc(func(ctx context.Context, conn Conn) error {
		conn.Go(ctx, h)
		<-conn.Done()
		return conn.Err()
	})
}

// ListenAndServe starts a jsonrpc2 server on the given address.  If
// idleTimeout is non-zero, ListenAndServe exits after there are no clients for
// this duration, otherwise it exits only on error.
func ListenAndServe(ctx context.Context, network, addr string, server StreamServer, idleTimeout time.Duration) error {
	ln, err := net.Listen(network, addr)
	if err != nil {
		return err
	}
	defer ln.Close()
	if network == "unix" {
		defer os.Remove(addr)
	}
	return Serve(ctx, ln, server, idleTimeout)
}

// Serve accepts incoming connections from the network, and handles them using
// the provided server. If idleTimeout is non-zero, ListenAndServe exits after
// there are no clients for this duration, otherwise it exits only on error.
func Serve(ctx context.Context, ln net.Listener, server StreamServer, idleTimeout time.Duration) error {
	newConns := make(chan net.Conn)
	closedConns := make(chan error)
	activeConns := 0
	var acceptErr error
	go func() {
		defer close(newConns)
		for {
			var nc net.Conn
			nc, acceptErr = ln.Accept()
			if acceptErr != nil {
				return
			}
			newConns <- nc
		}
	}()

	ctx, cancel := context.WithCancel(ctx)
	defer func() {
		// Signal the Accept goroutine to stop immediately
		// and terminate all newly-accepted connections until it returns.
		ln.Close()
		for nc := range newConns {
			nc.Close()
		}
		// Cancel pending ServeStream callbacks and wait for them to finish.
		cancel()
		for activeConns > 0 {
			err := <-closedConns
			if !isClosingError(err) {
				event.Error(ctx, "closed a connection", err)
			}
			activeConns--
		}
	}()

	// Max duration: ~290 years; surely that's long enough.
	const forever = math.MaxInt64
	if idleTimeout <= 0 {
		idleTimeout = forever
	}
	connTimer := time.NewTimer(idleTimeout)
	defer connTimer.Stop()

	for {
		select {
		case netConn, ok := <-newConns:
			if !ok {
				return acceptErr
			}
			if activeConns == 0 && !connTimer.Stop() {
				// connTimer.C may receive a value even after Stop returns.
				// (See https://golang.org/issue/37196.)
				<-connTimer.C
			}
			activeConns++
			stream := NewHeaderStream(netConn)
			go func() {
				conn := NewConn(stream)
				err := server.ServeStream(ctx, conn)
				stream.Close()
				closedConns <- err
			}()

		case err := <-closedConns:
			if !isClosingError(err) {
				event.Error(ctx, "closed a connection", err)
			}
			activeConns--
			if activeConns == 0 {
				connTimer.Reset(idleTimeout)
			}

		case <-connTimer.C:
			return ErrIdleTimeout

		case <-ctx.Done():
			return nil
		}
	}
}

// isClosingError reports if the error occurs normally during the process of
// closing a network connection. It uses imperfect heuristics that err on the
// side of false negatives, and should not be used for anything critical.
func isClosingError(err error) bool {
	if errors.Is(err, io.EOF) {
		return true
	}
	// Per https://github.com/golang/go/issues/4373, this error string should not
	// change. This is not ideal, but since the worst that could happen here is
	// some superfluous logging, it is acceptable.
	if err.Error() == "use of closed network connection" {
		return true
	}
	return false
}


================================================
FILE: internal/jsonrpc2/serve_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"net"
	"sync"
	"testing"
	"time"

	"golang.org/x/tools/internal/jsonrpc2/stack/stacktest"
	"golang.org/x/tools/internal/testenv"
)

func TestIdleTimeout(t *testing.T) {
	testenv.NeedsLocalhostNet(t)

	stacktest.NoLeak(t)
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	ln, err := net.Listen("tcp", "localhost:0")
	if err != nil {
		t.Fatal(err)
	}
	defer ln.Close()

	connect := func() net.Conn {
		conn, err := net.DialTimeout("tcp", ln.Addr().String(), 5*time.Second)
		if err != nil {
			panic(err)
		}
		return conn
	}

	server := HandlerServer(MethodNotFound)
	// connTimer := &fakeTimer{c: make(chan time.Time, 1)}
	var (
		runErr error
		wg     sync.WaitGroup
	)
	wg.Add(1)
	go func() {
		defer wg.Done()
		runErr = Serve(ctx, ln, server, 100*time.Millisecond)
	}()

	// Exercise some connection/disconnection patterns, and then assert that when
	// our timer fires, the server exits.
	conn1 := connect()
	conn2 := connect()
	conn1.Close()
	conn2.Close()
	conn3 := connect()
	conn3.Close()

	wg.Wait()

	if runErr != ErrIdleTimeout {
		t.Errorf("run() returned error %v, want %v", runErr, ErrIdleTimeout)
	}
}


================================================
FILE: internal/jsonrpc2/servertest/servertest.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package servertest provides utilities for running tests against a remote LSP
// server.
package servertest

import (
	"context"
	"fmt"
	"net"
	"strings"
	"sync"

	"golang.org/x/tools/internal/jsonrpc2"
)

// Connector is the interface used to connect to a server.
type Connector interface {
	Connect(context.Context) jsonrpc2.Conn
}

// TCPServer is a helper for executing tests against a remote jsonrpc2
// connection. Once initialized, its Addr field may be used to connect a
// jsonrpc2 client.
type TCPServer struct {
	*connList

	Addr string

	ln     net.Listener
	framer jsonrpc2.Framer
}

// NewTCPServer returns a new test server listening on local tcp port and
// serving incoming jsonrpc2 streams using the provided stream server. It
// panics on any error.
func NewTCPServer(ctx context.Context, server jsonrpc2.StreamServer, framer jsonrpc2.Framer) *TCPServer {
	ln, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		panic(fmt.Sprintf("servertest: failed to listen: %v", err))
	}
	if framer == nil {
		framer = jsonrpc2.NewHeaderStream
	}
	go jsonrpc2.Serve(ctx, ln, server, 0)
	return &TCPServer{Addr: ln.Addr().String(), ln: ln, framer: framer, connList: &connList{}}
}

// Connect dials the test server and returns a jsonrpc2 Connection that is
// ready for use.
func (s *TCPServer) Connect(_ context.Context) jsonrpc2.Conn {
	netConn, err := net.Dial("tcp", s.Addr)
	if err != nil {
		panic(fmt.Sprintf("servertest: failed to connect to test instance: %v", err))
	}
	conn := jsonrpc2.NewConn(s.framer(netConn))
	s.add(conn)
	return conn
}

// PipeServer is a test server that handles connections over io.Pipes.
type PipeServer struct {
	*connList
	server jsonrpc2.StreamServer
	framer jsonrpc2.Framer
}

// NewPipeServer returns a test server that can be connected to via io.Pipes.
func NewPipeServer(server jsonrpc2.StreamServer, framer jsonrpc2.Framer) *PipeServer {
	if framer == nil {
		framer = jsonrpc2.NewRawStream
	}
	return &PipeServer{server: server, framer: framer, connList: &connList{}}
}

// Connect creates new io.Pipes and binds them to the underlying StreamServer.
func (s *PipeServer) Connect(ctx context.Context) jsonrpc2.Conn {
	sPipe, cPipe := net.Pipe()
	serverStream := s.framer(sPipe)
	serverConn := jsonrpc2.NewConn(serverStream)
	s.add(serverConn)
	go s.server.ServeStream(ctx, serverConn)

	clientStream := s.framer(cPipe)
	clientConn := jsonrpc2.NewConn(clientStream)
	s.add(clientConn)
	return clientConn
}

// connList tracks closers to run when a testserver is closed.  This is a
// convenience, so that callers don't have to worry about closing each
// connection.
type connList struct {
	mu    sync.Mutex
	conns []jsonrpc2.Conn
}

func (l *connList) add(conn jsonrpc2.Conn) {
	l.mu.Lock()
	defer l.mu.Unlock()
	l.conns = append(l.conns, conn)
}

func (l *connList) Close() error {
	l.mu.Lock()
	defer l.mu.Unlock()
	var errmsgs []string
	for _, conn := range l.conns {
		if err := conn.Close(); err != nil {
			errmsgs = append(errmsgs, err.Error())
		}
	}
	if len(errmsgs) > 0 {
		return fmt.Errorf("closing errors:\n%s", strings.Join(errmsgs, "\n"))
	}
	return nil
}


================================================
FILE: internal/jsonrpc2/servertest/servertest_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package servertest

import (
	"context"
	"testing"
	"time"

	"golang.org/x/tools/internal/jsonrpc2"
)

type msg struct {
	Msg string
}

func fakeHandler(ctx context.Context, reply jsonrpc2.Replier, req jsonrpc2.Request) error {
	return reply(ctx, &msg{"pong"}, nil)
}

func TestTestServer(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()
	server := jsonrpc2.HandlerServer(fakeHandler)
	tcpTS := NewTCPServer(ctx, server, nil)
	defer tcpTS.Close()
	pipeTS := NewPipeServer(server, nil)
	defer pipeTS.Close()

	tests := []struct {
		name      string
		connector Connector
	}{
		{"tcp", tcpTS},
		{"pipe", pipeTS},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			conn := test.connector.Connect(ctx)
			conn.Go(ctx, jsonrpc2.MethodNotFound)
			var got msg
			if _, err := conn.Call(ctx, "ping", &msg{"ping"}, &got); err != nil {
				t.Fatal(err)
			}
			if want := "pong"; got.Msg != want {
				t.Errorf("conn.Call(...): returned %q, want %q", got, want)
			}
		})
	}
}


================================================
FILE: internal/jsonrpc2/stack/parse.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stack

import (
	"bufio"
	"io"
	"regexp"
	"strconv"
)

var (
	reBlank     = regexp.MustCompile(`^\s*$`)
	reGoroutine = regexp.MustCompile(`^\s*goroutine (\d+) \[([^\]]*)\]:\s*$`)
	reCall      = regexp.MustCompile(`^\s*` +
		`(created by )?` + //marker
		`(([\w/.]+/)?[\w]+)\.` + //package
		`(\(([^:.)]*)\)\.)?` + //optional type
		`([\w\.]+)` + //function
		`(\(.*\))?` + // args
		`\s*$`)
	rePos = regexp.MustCompile(`^\s*(.*):(\d+)( .*)?$`)
)

// Scanner splits an input stream into lines in a way that is consumable by
// the parser.
type Scanner struct {
	lines *bufio.Scanner
	done  bool
}

// NewScanner creates a scanner on top of a reader.
func NewScanner(r io.Reader) *Scanner {
	s := &Scanner{
		lines: bufio.NewScanner(r),
	}
	s.Skip() // prefill
	return s
}

// Peek returns the next line without consuming it.
func (s *Scanner) Peek() string {
	if s.done {
		return ""
	}
	return s.lines.Text()
}

// Skip consumes the next line without looking at it.
// Normally used after it has already been looked at using Peek.
func (s *Scanner) Skip() {
	if !s.lines.Scan() {
		s.done = true
	}
}

// Next consumes and returns the next line.
func (s *Scanner) Next() string {
	line := s.Peek()
	s.Skip()
	return line
}

// Done returns true if the scanner has reached the end of the underlying
// stream.
func (s *Scanner) Done() bool {
	return s.done
}

// Err returns true if the scanner has reached the end of the underlying
// stream.
func (s *Scanner) Err() error {
	return s.lines.Err()
}

// Match returns the submatchs of the regular expression against the next line.
// If it matched the line is also consumed.
func (s *Scanner) Match(re *regexp.Regexp) []string {
	if s.done {
		return nil
	}
	match := re.FindStringSubmatch(s.Peek())
	if match != nil {
		s.Skip()
	}
	return match
}

// SkipBlank skips any number of pure whitespace lines.
func (s *Scanner) SkipBlank() {
	for !s.done {
		line := s.Peek()
		if len(line) != 0 && !reBlank.MatchString(line) {
			return
		}
		s.Skip()
	}
}

// Parse the current contiguous block of goroutine stack traces until the
// scanned content no longer matches.
func Parse(scanner *Scanner) (Dump, error) {
	dump := Dump{}
	for {
		gr, ok := parseGoroutine(scanner)
		if !ok {
			return dump, nil
		}
		dump = append(dump, gr)
	}
}

func parseGoroutine(scanner *Scanner) (Goroutine, bool) {
	match := scanner.Match(reGoroutine)
	if match == nil {
		return Goroutine{}, false
	}
	id, _ := strconv.ParseInt(match[1], 0, 32)
	gr := Goroutine{
		ID:    int(id),
		State: match[2],
	}
	for {
		frame, ok := parseFrame(scanner)
		if !ok {
			scanner.SkipBlank()
			return gr, true
		}
		if frame.Position.Filename != "" {
			gr.Stack = append(gr.Stack, frame)
		}
	}
}

func parseFrame(scanner *Scanner) (Frame, bool) {
	fun, ok := parseFunction(scanner)
	if !ok {
		return Frame{}, false
	}
	frame := Frame{
		Function: fun,
	}
	frame.Position, ok = parsePosition(scanner)
	// if ok is false, then this is a broken state.
	// we got the func but not the file that must follow
	// the consumed line can be recovered from the frame
	//TODO: push back the fun raw
	return frame, ok
}

func parseFunction(scanner *Scanner) (Function, bool) {
	match := scanner.Match(reCall)
	if match == nil {
		return Function{}, false
	}
	return Function{
		Package: match[2],
		Type:    match[5],
		Name:    match[6],
	}, true
}

func parsePosition(scanner *Scanner) (Position, bool) {
	match := scanner.Match(rePos)
	if match == nil {
		return Position{}, false
	}
	line, _ := strconv.ParseInt(match[2], 0, 32)
	return Position{Filename: match[1], Line: int(line)}, true
}


================================================
FILE: internal/jsonrpc2/stack/process.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stack

import (
	"bytes"
	"fmt"
	"io"
	"runtime"
	"sort"
)

// Capture get the current stack traces from the runtime.
func Capture() Dump {
	buf := make([]byte, 2<<20)
	buf = buf[:runtime.Stack(buf, true)]
	scanner := NewScanner(bytes.NewReader(buf))
	dump, _ := Parse(scanner)
	return dump
}

// Summarize a dump for easier consumption.
// This collates goroutines with equivalent stacks.
func Summarize(dump Dump) Summary {
	s := Summary{
		Total: len(dump),
	}
	for _, gr := range dump {
		s.addGoroutine(gr)
	}
	return s
}

// Process and input stream to an output stream, summarizing any stacks that
// are detected in place.
func Process(out io.Writer, in io.Reader) error {
	scanner := NewScanner(in)
	for {
		dump, err := Parse(scanner)
		summary := Summarize(dump)
		switch {
		case len(dump) > 0:
			fmt.Fprintf(out, "%+v\n\n", summary)
		case err != nil:
			return err
		case scanner.Done():
			return scanner.Err()
		default:
			// must have been a line that is not part of a dump
			fmt.Fprintln(out, scanner.Next())
		}
	}
}

// Diff calculates the delta between two dumps.
func Diff(before, after Dump) Delta {
	result := Delta{}
	processed := make(map[int]bool)
	for _, gr := range before {
		processed[gr.ID] = false
	}
	for _, gr := range after {
		if _, found := processed[gr.ID]; found {
			result.Shared = append(result.Shared, gr)
		} else {
			result.After = append(result.After, gr)
		}
		processed[gr.ID] = true
	}
	for _, gr := range before {
		if done := processed[gr.ID]; !done {
			result.Before = append(result.Before, gr)
		}
	}
	return result
}

// TODO: do we want to allow contraction of stacks before comparison?
func (s *Summary) addGoroutine(gr Goroutine) {
	index := sort.Search(len(s.Calls), func(i int) bool {
		return !s.Calls[i].Stack.less(gr.Stack)
	})
	if index >= len(s.Calls) || !s.Calls[index].Stack.equal(gr.Stack) {
		// insert new stack, first increase the length
		s.Calls = append(s.Calls, Call{})
		// move the top part upward to make space
		copy(s.Calls[index+1:], s.Calls[index:])
		// insert the new call
		s.Calls[index] = Call{
			Stack: gr.Stack,
		}
	}
	// merge the goroutine into the matched call
	s.Calls[index].merge(gr)
}

// TODO: do we want other grouping strategies?
func (c *Call) merge(gr Goroutine) {
	for i := range c.Groups {
		canditate := &c.Groups[i]
		if canditate.State == gr.State {
			canditate.Goroutines = append(canditate.Goroutines, gr)
			return
		}
	}
	c.Groups = append(c.Groups, Group{
		State:      gr.State,
		Goroutines: []Goroutine{gr},
	})
}


================================================
FILE: internal/jsonrpc2/stack/stack.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package stack provides support for parsing standard goroutine stack traces.
package stack

import (
	"fmt"
	"text/tabwriter"
)

// Dump is a raw set of goroutines and their stacks.
type Dump []Goroutine

// Goroutine is a single parsed goroutine dump.
type Goroutine struct {
	State string // state that the goroutine is in.
	ID    int    // id of the goroutine.
	Stack Stack  // call frames that make up the stack
}

// Stack is a set of frames in a callstack.
type Stack []Frame

// Frame is a point in a call stack.
type Frame struct {
	Function Function
	Position Position
}

// Function is the function called at a frame.
type Function struct {
	Package string // package name of function if known
	Type    string // if set function is a method of this type
	Name    string // function name of the frame
}

// Position is the file position for a frame.
type Position struct {
	Filename string // source filename
	Line     int    // line number within file
}

// Summary is a set of stacks processed and collated into Calls.
type Summary struct {
	Total int    // the total count of goroutines in the summary
	Calls []Call // the collated stack traces
}

// Call is set of goroutines that all share the same callstack.
// They will be grouped by state.
type Call struct {
	Stack  Stack   // the shared callstack information
	Groups []Group // the sets of goroutines with the same state
}

// Group is a set of goroutines with the same stack that are in the same state.
type Group struct {
	State      string      // the shared state of the goroutines
	Goroutines []Goroutine // the set of goroutines in this group
}

// Delta represents the difference between two stack dumps.
type Delta struct {
	Before Dump // The goroutines that were only in the before set.
	Shared Dump // The goroutines that were in both sets.
	After  Dump // The goroutines that were only in the after set.
}

func (s Stack) equal(other Stack) bool {
	if len(s) != len(other) {
		return false
	}
	for i, frame := range s {
		if !frame.equal(other[i]) {
			return false
		}
	}
	return true
}

func (s Stack) less(other Stack) bool {
	for i, frame := range s {
		if i >= len(other) {
			return false
		}
		if frame.less(other[i]) {
			return true
		}
		if !frame.equal(other[i]) {
			return false
		}
	}
	return len(s) < len(other)
}

func (f Frame) equal(other Frame) bool {
	return f.Position.equal(other.Position)
}

func (f Frame) less(other Frame) bool {
	return f.Position.less(other.Position)
}

func (p Position) equal(other Position) bool {
	return p.Filename == other.Filename && p.Line == other.Line
}

func (p Position) less(other Position) bool {
	if p.Filename < other.Filename {
		return true
	}
	if p.Filename > other.Filename {
		return false
	}
	return p.Line < other.Line
}

func (s Summary) Format(w fmt.State, r rune) {
	tw := tabwriter.NewWriter(w, 0, 0, 1, ' ', 0)
	for i, c := range s.Calls {
		if i > 0 {
			fmt.Fprintf(tw, "\n\n")
			tw.Flush()
		}
		fmt.Fprint(tw, c)
	}
	tw.Flush()
	if s.Total > 0 && w.Flag('+') {
		fmt.Fprintf(w, "\n\n%d goroutines, %d unique", s.Total, len(s.Calls))
	}
}

func (c Call) Format(w fmt.State, r rune) {
	for i, g := range c.Groups {
		if i > 0 {
			fmt.Fprint(w, " ")
		}
		fmt.Fprint(w, g)
	}
	for _, f := range c.Stack {
		fmt.Fprintf(w, "\n%v", f)
	}
}

func (g Group) Format(w fmt.State, r rune) {
	fmt.Fprintf(w, "[%v]: ", g.State)
	for i, gr := range g.Goroutines {
		if i > 0 {
			fmt.Fprint(w, ", ")
		}
		fmt.Fprintf(w, "$%d", gr.ID)
	}
}

func (f Frame) Format(w fmt.State, c rune) {
	fmt.Fprintf(w, "%v:\t%v", f.Position, f.Function)
}

func (f Function) Format(w fmt.State, c rune) {
	if f.Type != "" {
		fmt.Fprintf(w, "(%v).", f.Type)
	}
	fmt.Fprintf(w, "%v", f.Name)
}

func (p Position) Format(w fmt.State, c rune) {
	fmt.Fprintf(w, "%v:%v", p.Filename, p.Line)
}


================================================
FILE: internal/jsonrpc2/stack/stack_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stack_test

import (
	"bytes"
	"strings"
	"testing"

	"golang.org/x/tools/internal/jsonrpc2/stack"
)

func TestProcess(t *testing.T) {
	for _, test := range []struct{ name, input, expect string }{{
		name:   `empty`,
		input:  ``,
		expect: ``,
	}, {
		name:  `no_frame`,
		input: `goroutine 1 [running]:`,
		expect: `
[running]: $1

1 goroutines, 1 unique
`,
	}, {
		name: `one_frame`,
		input: `
goroutine 1 [running]:
package.function(args)
	file.go:10
`,
		expect: `
[running]: $1
file.go:10: function

1 goroutines, 1 unique
`,
	}, {
		name: `one_call`,
		input: `
goroutine 1 [running]:
package1.functionA(args)
	file1.go:10
package2.functionB(args)
	file2.go:20
package3.functionC(args)
	file3.go:30
`,
		expect: `
[running]: $1
file1.go:10: functionA
file2.go:20: functionB
file3.go:30: functionC

1 goroutines, 1 unique
`,
	}, {
		name: `two_call`,
		input: `
goroutine 1 [running]:
package1.functionA(args)
	file1.go:10
goroutine 2 [running]:
package2.functionB(args)
	file2.go:20
`,
		expect: `
[running]: $1
file1.go:10: functionA

[running]: $2
file2.go:20: functionB

2 goroutines, 2 unique
`,
	}, {
		name: `merge_call`,
		input: `
goroutine 1 [running]:
package1.functionA(args)
	file1.go:10
goroutine 2 [running]:
package1.functionA(args)
	file1.go:10
`,
		expect: `
[running]: $1, $2
file1.go:10: functionA

2 goroutines, 1 unique
`,
	}, {
		name: `alternating_call`,
		input: `
goroutine 1 [running]:
package1.functionA(args)
	file1.go:10
goroutine 2 [running]:
package2.functionB(args)
	file2.go:20
goroutine 3 [running]:
package1.functionA(args)
	file1.go:10
goroutine 4 [running]:
package2.functionB(args)
	file2.go:20
goroutine 5 [running]:
package1.functionA(args)
	file1.go:10
goroutine 6 [running]:
package2.functionB(args)
	file2.go:20
`,
		expect: `
[running]: $1, $3, $5
file1.go:10: functionA

[running]: $2, $4, $6
file2.go:20: functionB

6 goroutines, 2 unique
`,
	}, {
		name: `sort_calls`,
		input: `
goroutine 1 [running]:
package3.functionC(args)
	file3.go:30
goroutine 2 [running]:
package2.functionB(args)
	file2.go:20
goroutine 3 [running]:
package1.functionA(args)
	file1.go:10
`,
		expect: `
[running]: $3
file1.go:10: functionA

[running]: $2
file2.go:20: functionB

[running]: $1
file3.go:30: functionC

3 goroutines, 3 unique
`,
	}, {
		name: `real_single`,
		input: `
panic: oops

goroutine 53 [running]:
golang.org/x/tools/internal/jsonrpc2_test.testHandler.func1(0x1240c20, 0xc000013350, 0xc0000133b0, 0x1240ca0, 0xc00002ab00, 0x3, 0x3)
	/work/tools/internal/jsonrpc2/jsonrpc2_test.go:160 +0x74c
golang.org/x/tools/internal/jsonrpc2.(*Conn).Run(0xc000204330, 0x1240c20, 0xc000204270, 0x1209570, 0xc000212120, 0x1242700)
	/work/tools/internal/jsonrpc2/jsonrpc2.go:187 +0x777
golang.org/x/tools/internal/jsonrpc2_test.run.func1(0x123ebe0, 0xc000206018, 0x123ec20, 0xc000206010, 0xc0002080a0, 0xc000204330, 0x1240c20, 0xc000204270, 0xc000212120)
	/work/tools/internal/jsonrpc2/jsonrpc2_test.go:131 +0xe2
created by golang.org/x/tools/internal/jsonrpc2_test.run
	/work/tools/internal/jsonrpc2/jsonrpc2_test.go:121 +0x263
FAIL    golang.org/x/tools/internal/jsonrpc2    0.252s
FAIL
`,
		expect: `
panic: oops

[running]: $53
/work/tools/internal/jsonrpc2/jsonrpc2_test.go:160: testHandler.func1
/work/tools/internal/jsonrpc2/jsonrpc2.go:187:      (*Conn).Run
/work/tools/internal/jsonrpc2/jsonrpc2_test.go:131: run.func1
/work/tools/internal/jsonrpc2/jsonrpc2_test.go:121: run

1 goroutines, 1 unique

FAIL    golang.org/x/tools/internal/jsonrpc2    0.252s
FAIL
`,
	}} {
		t.Run(test.name, func(t *testing.T) {
			buf := &bytes.Buffer{}
			stack.Process(buf, strings.NewReader(test.input))
			expect := strings.TrimSpace(test.expect)
			got := strings.TrimSpace(buf.String())
			if got != expect {
				t.Errorf("got:\n%s\nexpect:\n%s", got, expect)
			}
		})
	}
}


================================================
FILE: internal/jsonrpc2/stack/stacktest/stacktest.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stacktest

import (
	"testing"
	"time"

	"golang.org/x/tools/internal/jsonrpc2/stack"
)

// this is only needed to support pre 1.14 when testing.TB did not have Cleanup
type withCleanup interface {
	Cleanup(func())
}

// the maximum amount of time to wait for goroutines to clean themselves up.
const maxWait = time.Second

// NoLeak checks that a test (or benchmark) does not leak any goroutines.
func NoLeak(t testing.TB) {
	c, ok := t.(withCleanup)
	if !ok {
		return
	}
	before := stack.Capture()
	c.Cleanup(func() {
		var delta stack.Delta
		start := time.Now()
		delay := time.Millisecond
		for {
			after := stack.Capture()
			delta = stack.Diff(before, after)
			if len(delta.After) == 0 {
				// no leaks
				return
			}
			if time.Since(start) > maxWait {
				break
			}
			time.Sleep(delay)
			delay *= 2
		}
		// it's been long enough, and leaks are still present
		summary := stack.Summarize(delta.After)
		t.Errorf("goroutine leak detected:\n%+v", summary)
	})
}


================================================
FILE: internal/jsonrpc2/stream.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net"
	"strconv"
	"strings"
)

// Stream abstracts the transport mechanics from the JSON RPC protocol.
// A Conn reads and writes messages using the stream it was provided on
// construction, and assumes that each call to Read or Write fully transfers
// a single message, or returns an error.
// A stream is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Stream interface {
	// Read gets the next message from the stream.
	Read(context.Context) (Message, int64, error)
	// Write sends a message to the stream.
	Write(context.Context, Message) (int64, error)
	// Close closes the connection.
	// Any blocked Read or Write operations will be unblocked and return errors.
	Close() error
}

// Framer wraps a network connection up into a Stream.
// It is responsible for the framing and encoding of messages into wire form.
// NewRawStream and NewHeaderStream are implementations of a Framer.
type Framer func(conn net.Conn) Stream

// NewRawStream returns a Stream built on top of a net.Conn.
// The messages are sent with no wrapping, and rely on json decode consistency
// to determine message boundaries.
func NewRawStream(conn net.Conn) Stream {
	return &rawStream{
		conn: conn,
		in:   json.NewDecoder(conn),
	}
}

type rawStream struct {
	conn net.Conn
	in   *json.Decoder
}

func (s *rawStream) Read(ctx context.Context) (Message, int64, error) {
	select {
	case <-ctx.Done():
		return nil, 0, ctx.Err()
	default:
	}
	var raw json.RawMessage
	if err := s.in.Decode(&raw); err != nil {
		return nil, 0, err
	}
	msg, err := DecodeMessage(raw)
	return msg, int64(len(raw)), err
}

func (s *rawStream) Write(ctx context.Context, msg Message) (int64, error) {
	select {
	case <-ctx.Done():
		return 0, ctx.Err()
	default:
	}
	data, err := json.Marshal(msg)
	if err != nil {
		return 0, fmt.Errorf("marshaling message: %v", err)
	}
	n, err := s.conn.Write(data)
	return int64(n), err
}

func (s *rawStream) Close() error {
	return s.conn.Close()
}

// NewHeaderStream returns a Stream built on top of a net.Conn.
// The messages are sent with HTTP content length and MIME type headers.
// This is the format used by LSP and others.
func NewHeaderStream(conn net.Conn) Stream {
	return &headerStream{
		conn: conn,
		in:   bufio.NewReader(conn),
	}
}

type headerStream struct {
	conn net.Conn
	in   *bufio.Reader
}

func (s *headerStream) Read(ctx context.Context) (Message, int64, error) {
	select {
	case <-ctx.Done():
		return nil, 0, ctx.Err()
	default:
	}
	var total, length int64
	// read the header, stop on the first empty line
	for {
		line, err := s.in.ReadString('\n')
		total += int64(len(line))
		if err != nil {
			return nil, total, fmt.Errorf("failed reading header line: %w", err)
		}
		line = strings.TrimSpace(line)
		// check we have a header line
		if line == "" {
			break
		}
		colon := strings.IndexRune(line, ':')
		if colon < 0 {
			return nil, total, fmt.Errorf("invalid header line %q", line)
		}
		name, value := line[:colon], strings.TrimSpace(line[colon+1:])
		switch name {
		case "Content-Length":
			if length, err = strconv.ParseInt(value, 10, 32); err != nil {
				return nil, total, fmt.Errorf("failed parsing Content-Length: %v", value)
			}
			if length <= 0 {
				return nil, total, fmt.Errorf("invalid Content-Length: %v", length)
			}
		default:
			// ignoring unknown headers
		}
	}
	if length == 0 {
		return nil, total, fmt.Errorf("missing Content-Length header")
	}
	data := make([]byte, length)
	if _, err := io.ReadFull(s.in, data); err != nil {
		return nil, total, err
	}
	total += length
	msg, err := DecodeMessage(data)
	return msg, total, err
}

func (s *headerStream) Write(ctx context.Context, msg Message) (int64, error) {
	select {
	case <-ctx.Done():
		return 0, ctx.Err()
	default:
	}
	data, err := json.Marshal(msg)
	if err != nil {
		return 0, fmt.Errorf("marshaling message: %v", err)
	}
	n, err := fmt.Fprintf(s.conn, "Content-Length: %v\r\n\r\n", len(data))
	total := int64(n)
	if err == nil {
		n, err = s.conn.Write(data)
		total += int64(n)
	}
	return total, err
}

func (s *headerStream) Close() error {
	return s.conn.Close()
}


================================================
FILE: internal/jsonrpc2/wire.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"encoding/json"
	"fmt"
)

// this file contains the go forms of the wire specification
// see http://www.jsonrpc.org/specification for details

var (
	// ErrUnknown should be used for all non coded errors.
	ErrUnknown = NewError(-32001, "JSON RPC unknown error")
	// ErrParse is used when invalid JSON was received by the server.
	ErrParse = NewError(-32700, "JSON RPC parse error")
	//ErrInvalidRequest is used when the JSON sent is not a valid Request object.
	ErrInvalidRequest = NewError(-32600, "JSON RPC invalid request")
	// ErrMethodNotFound should be returned by the handler when the method does
	// not exist / is not available.
	ErrMethodNotFound = NewError(-32601, "JSON RPC method not found")
	// ErrInvalidParams should be returned by the handler when method
	// parameter(s) were invalid.
	ErrInvalidParams = NewError(-32602, "JSON RPC invalid params")
	// ErrInternal is not currently returned but defined for completeness.
	ErrInternal = NewError(-32603, "JSON RPC internal error")

	//ErrServerOverloaded is returned when a message was refused due to a
	//server being temporarily unable to accept any new messages.
	ErrServerOverloaded = NewError(-32000, "JSON RPC overloaded")
)

// wireRequest is sent to a server to represent a Call or Notify operation.
type wireRequest struct {
	// VersionTag is always encoded as the string "2.0"
	VersionTag wireVersionTag `json:"jsonrpc"`
	// Method is a string containing the method name to invoke.
	Method string `json:"method"`
	// Params is either a struct or an array with the parameters of the method.
	Params *json.RawMessage `json:"params,omitempty"`
	// The id of this request, used to tie the Response back to the request.
	// Will be either a string or a number. If not set, the Request is a notify,
	// and no response is possible.
	ID *ID `json:"id,omitempty"`
}

// wireResponse is a reply to a Request.
// It will always have the ID field set to tie it back to a request, and will
// have either the Result or Error fields set depending on whether it is a
// success or failure response.
type wireResponse struct {
	// VersionTag is always encoded as the string "2.0"
	VersionTag wireVersionTag `json:"jsonrpc"`
	// Result is the response value, and is required on success.
	Result *json.RawMessage `json:"result,omitempty"`
	// Error is a structured error response if the call fails.
	Error *WireError `json:"error,omitempty"`
	// ID must be set and is the identifier of the Request this is a response to.
	ID *ID `json:"id,omitempty"`
}

// wireCombined has all the fields of both Request and Response.
// We can decode this and then work out which it is.
type wireCombined struct {
	VersionTag wireVersionTag   `json:"jsonrpc"`
	ID         *ID              `json:"id,omitempty"`
	Method     string           `json:"method"`
	Params     *json.RawMessage `json:"params,omitempty"`
	Result     *json.RawMessage `json:"result,omitempty"`
	Error      *WireError       `json:"error,omitempty"`
}

// WireError represents a structured error in a Response.
type WireError struct {
	// Code is an error code indicating the type of failure.
	Code int64 `json:"code"`
	// Message is a short description of the error.
	Message string `json:"message"`
	// Data is optional structured data containing additional information about the error.
	Data *json.RawMessage `json:"data,omitempty"`
}

// wireVersionTag is a special 0 sized struct that encodes as the jsonrpc version
// tag.
// It will fail during decode if it is not the correct version tag in the
// stream.
type wireVersionTag struct{}

// ID is a Request identifier.
type ID struct {
	name   string
	number int64
}

func NewError(code int64, message string) error {
	return &WireError{
		Code:    code,
		Message: message,
	}
}

func (err *WireError) Error() string {
	return err.Message
}

func (wireVersionTag) MarshalJSON() ([]byte, error) {
	return json.Marshal("2.0")
}

func (wireVersionTag) UnmarshalJSON(data []byte) error {
	version := ""
	if err := json.Unmarshal(data, &version); err != nil {
		return err
	}
	if version != "2.0" {
		return fmt.Errorf("invalid RPC version %v", version)
	}
	return nil
}

// NewIntID returns a new numerical request ID.
func NewIntID(v int64) ID { return ID{number: v} }

// NewStringID returns a new string request ID.
func NewStringID(v string) ID { return ID{name: v} }

// Format writes the ID to the formatter.
// If the rune is q the representation is non ambiguous,
// string forms are quoted, number forms are preceded by a #
func (id ID) Format(f fmt.State, r rune) {
	numF, strF := `%d`, `%s`
	if r == 'q' {
		numF, strF = `#%d`, `%q`
	}
	switch {
	case id.name != "":
		fmt.Fprintf(f, strF, id.name)
	default:
		fmt.Fprintf(f, numF, id.number)
	}
}

func (id *ID) MarshalJSON() ([]byte, error) {
	if id.name != "" {
		return json.Marshal(id.name)
	}
	return json.Marshal(id.number)
}

func (id *ID) UnmarshalJSON(data []byte) error {
	*id = ID{}
	if err := json.Unmarshal(data, &id.number); err == nil {
		return nil
	}
	return json.Unmarshal(data, &id.name)
}


================================================
FILE: internal/jsonrpc2/wire_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2_test

import (
	"bytes"
	"encoding/json"
	"fmt"
	"testing"

	"golang.org/x/tools/internal/jsonrpc2"
)

var wireIDTestData = []struct {
	name    string
	id      jsonrpc2.ID
	encoded []byte
	plain   string
	quoted  string
}{
	{
		name:    `empty`,
		encoded: []byte(`0`),
		plain:   `0`,
		quoted:  `#0`,
	}, {
		name:    `number`,
		id:      jsonrpc2.NewIntID(43),
		encoded: []byte(`43`),
		plain:   `43`,
		quoted:  `#43`,
	}, {
		name:    `string`,
		id:      jsonrpc2.NewStringID("life"),
		encoded: []byte(`"life"`),
		plain:   `life`,
		quoted:  `"life"`,
	},
}

func TestIDFormat(t *testing.T) {
	for _, test := range wireIDTestData {
		t.Run(test.name, func(t *testing.T) {
			if got := fmt.Sprint(test.id); got != test.plain {
				t.Errorf("got %s expected %s", got, test.plain)
			}
			if got := fmt.Sprintf("%q", test.id); got != test.quoted {
				t.Errorf("got %s want %s", got, test.quoted)
			}
		})
	}
}

func TestIDEncode(t *testing.T) {
	for _, test := range wireIDTestData {
		t.Run(test.name, func(t *testing.T) {
			data, err := json.Marshal(&test.id)
			if err != nil {
				t.Fatal(err)
			}
			checkJSON(t, data, test.encoded)
		})
	}
}

func TestIDDecode(t *testing.T) {
	for _, test := range wireIDTestData {
		t.Run(test.name, func(t *testing.T) {
			var got *jsonrpc2.ID
			if err := json.Unmarshal(test.encoded, &got); err != nil {
				t.Fatal(err)
			}
			if got == nil {
				t.Errorf("got nil want %s", test.id)
			} else if *got != test.id {
				t.Errorf("got %s want %s", got, test.id)
			}
		})
	}
}

func TestErrorEncode(t *testing.T) {
	b, err := json.Marshal(jsonrpc2.NewError(0, ""))
	if err != nil {
		t.Fatal(err)
	}
	checkJSON(t, b, []byte(`{
		"code": 0,
		"message": ""
	}`))
}

func TestErrorResponse(t *testing.T) {
	// originally reported in #39719, this checks that result is not present if
	// it is an error response
	r, _ := jsonrpc2.NewResponse(jsonrpc2.NewIntID(3), nil, fmt.Errorf("computing fix edits"))
	data, err := json.Marshal(r)
	if err != nil {
		t.Fatal(err)
	}
	checkJSON(t, data, []byte(`{
		"jsonrpc":"2.0",
		"error":{
			"code":0,
			"message":"computing fix edits"
		},
		"id":3
	}`))
}

func checkJSON(t *testing.T, got, want []byte) {
	// compare the compact form, to allow for formatting differences
	g := &bytes.Buffer{}
	if err := json.Compact(g, []byte(got)); err != nil {
		t.Fatal(err)
	}
	w := &bytes.Buffer{}
	if err := json.Compact(w, []byte(want)); err != nil {
		t.Fatal(err)
	}
	if g.String() != w.String() {
		t.Fatalf("Got:\n%s\nWant:\n%s", g, w)
	}
}


================================================
FILE: internal/jsonrpc2_v2/conn.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"sync"
	"sync/atomic"
	"time"
)

// Binder builds a connection configuration.
// This may be used in servers to generate a new configuration per connection.
// ConnectionOptions itself implements Binder returning itself unmodified, to
// allow for the simple cases where no per connection information is needed.
type Binder interface {
	// Bind returns the ConnectionOptions to use when establishing the passed-in
	// Connection.
	//
	// The connection is not ready to use when Bind is called,
	// but Bind may close it without reading or writing to it.
	Bind(context.Context, *Connection) ConnectionOptions
}

// A BinderFunc implements the Binder interface for a standalone Bind function.
type BinderFunc func(context.Context, *Connection) ConnectionOptions

func (f BinderFunc) Bind(ctx context.Context, c *Connection) ConnectionOptions {
	return f(ctx, c)
}

var _ Binder = BinderFunc(nil)

// ConnectionOptions holds the options for new connections.
type ConnectionOptions struct {
	// Framer allows control over the message framing and encoding.
	// If nil, HeaderFramer will be used.
	Framer Framer
	// Preempter allows registration of a pre-queue message handler.
	// If nil, no messages will be preempted.
	Preempter Preempter
	// Handler is used as the queued message handler for inbound messages.
	// If nil, all responses will be ErrNotHandled.
	Handler Handler
	// OnInternalError, if non-nil, is called with any internal errors that occur
	// while serving the connection, such as protocol errors or invariant
	// violations. (If nil, internal errors result in panics.)
	OnInternalError func(error)
}

// Connection manages the jsonrpc2 protocol, connecting responses back to their
// calls.
// Connection is bidirectional; it does not have a designated server or client
// end.
type Connection struct {
	seq int64 // must only be accessed using atomic operations

	stateMu sync.Mutex
	state   inFlightState // accessed only in updateInFlight
	done    chan struct{} // closed (under stateMu) when state.closed is true and all goroutines have completed

	writer chan Writer // 1-buffered; stores the writer when not in use

	handler Handler

	onInternalError func(error)
	onDone          func()
}

// inFlightState records the state of the incoming and outgoing calls on a
// Connection.
type inFlightState struct {
	connClosing bool  // true when the Connection's Close method has been called
	reading     bool  // true while the readIncoming goroutine is running
	readErr     error // non-nil when the readIncoming goroutine exits (typically io.EOF)
	writeErr    error // non-nil if a call to the Writer has failed with a non-canceled Context

	// closer shuts down and cleans up the Reader and Writer state, ideally
	// interrupting any Read or Write call that is currently blocked. It is closed
	// when the state is idle and one of: connClosing is true, readErr is non-nil,
	// or writeErr is non-nil.
	//
	// After the closer has been invoked, the closer field is set to nil
	// and the closeErr field is simultaneously set to its result.
	closer   io.Closer
	closeErr error // error returned from closer.Close

	outgoingCalls         map[ID]*AsyncCall // calls only
	outgoingNotifications int               // # of notifications awaiting "write"

	// incoming stores the total number of incoming calls and notifications
	// that have not yet written or processed a result.
	incoming int

	incomingByID map[ID]*incomingRequest // calls only

	// handlerQueue stores the backlog of calls and notifications that were not
	// already handled by a preempter.
	// The queue does not include the request currently being handled (if any).
	handlerQueue   []*incomingRequest
	handlerRunning bool
}

// updateInFlight locks the state of the connection's in-flight requests, allows
// f to mutate that state, and closes the connection if it is idle and either
// is closing or has a read or write error.
func (c *Connection) updateInFlight(f func(*inFlightState)) {
	c.stateMu.Lock()
	defer c.stateMu.Unlock()

	s := &c.state

	f(s)

	select {
	case <-c.done:
		// The connection was already completely done at the start of this call to
		// updateInFlight, so it must remain so. (The call to f should have noticed
		// that and avoided making any updates that would cause the state to be
		// non-idle.)
		if !s.idle() {
			panic("jsonrpc2_v2: updateInFlight transitioned to non-idle when already done")
		}
		return
	default:
	}

	if s.idle() && s.shuttingDown(ErrUnknown) != nil {
		if s.closer != nil {
			s.closeErr = s.closer.Close()
			s.closer = nil // prevent duplicate Close calls
		}
		if s.reading {
			// The readIncoming goroutine is still running. Our call to Close should
			// cause it to exit soon, at which point it will make another call to
			// updateInFlight, set s.reading to false, and mark the Connection done.
		} else {
			// The readIncoming goroutine has exited, or never started to begin with.
			// Since everything else is idle, we're completely done.
			if c.onDone != nil {
				c.onDone()
			}
			close(c.done)
		}
	}
}

// idle reports whether the connection is in a state with no pending calls or
// notifications.
//
// If idle returns true, the readIncoming goroutine may still be running,
// but no other goroutines are doing work on behalf of the connection.
func (s *inFlightState) idle() bool {
	return len(s.outgoingCalls) == 0 && s.outgoingNotifications == 0 && s.incoming == 0 && !s.handlerRunning
}

// shuttingDown reports whether the connection is in a state that should
// disallow new (incoming and outgoing) calls. It returns either nil or
// an error that is or wraps the provided errClosing.
func (s *inFlightState) shuttingDown(errClosing error) error {
	if s.connClosing {
		// If Close has been called explicitly, it doesn't matter what state the
		// Reader and Writer are in: we shouldn't be starting new work because the
		// caller told us not to start new work.
		return errClosing
	}
	if s.readErr != nil {
		// If the read side of the connection is broken, we cannot read new call
		// requests, and cannot read responses to our outgoing calls.
		return fmt.Errorf("%w: %v", errClosing, s.readErr)
	}
	if s.writeErr != nil {
		// If the write side of the connection is broken, we cannot write responses
		// for incoming calls, and cannot write requests for outgoing calls.
		return fmt.Errorf("%w: %v", errClosing, s.writeErr)
	}
	return nil
}

// incomingRequest is used to track an incoming request as it is being handled
type incomingRequest struct {
	*Request // the request being processed
	ctx      context.Context
	cancel   context.CancelFunc
}

// Bind returns the options unmodified.
func (o ConnectionOptions) Bind(context.Context, *Connection) ConnectionOptions {
	return o
}

// A ConnectionConfig configures a bidirectional jsonrpc2 connection.
type ConnectionConfig struct {
	Reader          Reader                    // required
	Writer          Writer                    // required
	Closer          io.Closer                 // required
	Preempter       Preempter                 // optional
	Bind            func(*Connection) Handler // required
	OnDone          func()                    // optional
	OnInternalError func(error)               // optional
}

// NewConnection creates a new [Connection] object and starts processing
// incoming messages.
func NewConnection(ctx context.Context, cfg ConnectionConfig) *Connection {
	ctx = notDone{ctx}

	c := &Connection{
		state:           inFlightState{closer: cfg.Closer},
		done:            make(chan struct{}),
		writer:          make(chan Writer, 1),
		onDone:          cfg.OnDone,
		onInternalError: cfg.OnInternalError,
	}
	c.handler = cfg.Bind(c)
	c.writer <- cfg.Writer
	c.start(ctx, cfg.Reader, cfg.Preempter)
	return c
}

// bindConnection creates a new connection and runs it.
//
// This is used by the Dial and Serve functions to build the actual connection.
//
// The connection is closed automatically (and its resources cleaned up) when
// the last request has completed after the underlying ReadWriteCloser breaks,
// but it may be stopped earlier by calling Close (for a clean shutdown).
func bindConnection(bindCtx context.Context, rwc io.ReadWriteCloser, binder Binder, onDone func()) *Connection {
	// TODO: Should we create a new event span here?
	// This will propagate cancellation from ctx; should it?
	ctx := notDone{bindCtx}

	c := &Connection{
		state:  inFlightState{closer: rwc},
		done:   make(chan struct{}),
		writer: make(chan Writer, 1),
		onDone: onDone,
	}
	// It's tempting to set a finalizer on c to verify that the state has gone
	// idle when the connection becomes unreachable. Unfortunately, the Binder
	// interface makes that unsafe: it allows the Handler to close over the
	// Connection, which could create a reference cycle that would cause the
	// Connection to become uncollectable.

	options := binder.Bind(bindCtx, c)
	framer := options.Framer
	if framer == nil {
		framer = HeaderFramer()
	}
	c.handler = options.Handler
	if c.handler == nil {
		c.handler = defaultHandler{}
	}
	c.onInternalError = options.OnInternalError

	c.writer <- framer.Writer(rwc)
	reader := framer.Reader(rwc)
	c.start(ctx, reader, options.Preempter)
	return c
}

func (c *Connection) start(ctx context.Context, reader Reader, preempter Preempter) {
	c.updateInFlight(func(s *inFlightState) {
		select {
		case <-c.done:
			// Bind already closed the connection; don't start a goroutine to read it.
			return
		default:
		}

		// The goroutine started here will continue until the underlying stream is closed.
		//
		// (If the Binder closed the Connection already, this should error out and
		// return almost immediately.)
		s.reading = true
		go c.readIncoming(ctx, reader, preempter)
	})
}

// Notify invokes the target method but does not wait for a response.
// The params will be marshaled to JSON before sending over the wire, and will
// be handed to the method invoked.
func (c *Connection) Notify(ctx context.Context, method string, params any) (err error) {
	attempted := false

	defer func() {
		if attempted {
			c.updateInFlight(func(s *inFlightState) {
				s.outgoingNotifications--
			})
		}
	}()

	c.updateInFlight(func(s *inFlightState) {
		// If the connection is shutting down, allow outgoing notifications only if
		// there is at least one call still in flight. The number of calls in flight
		// cannot increase once shutdown begins, and allowing outgoing notifications
		// may permit notifications that will cancel in-flight calls.
		if len(s.outgoingCalls) == 0 && len(s.incomingByID) == 0 {
			err = s.shuttingDown(ErrClientClosing)
			if err != nil {
				return
			}
		}
		s.outgoingNotifications++
		attempted = true
	})
	if err != nil {
		return err
	}

	notify, err := NewNotification(method, params)
	if err != nil {
		return fmt.Errorf("marshaling notify parameters: %v", err)
	}

	return c.write(ctx, notify)
}

// Call invokes the target method and returns an object that can be used to await the response.
// The params will be marshaled to JSON before sending over the wire, and will
// be handed to the method invoked.
// You do not have to wait for the response, it can just be ignored if not needed.
// If sending the call failed, the response will be ready and have the error in it.
func (c *Connection) Call(ctx context.Context, method string, params any) *AsyncCall {
	// Generate a new request identifier.
	id := Int64ID(atomic.AddInt64(&c.seq, 1))

	ac := &AsyncCall{
		id:    id,
		ready: make(chan struct{}),
	}
	// When this method returns, either ac is retired, or the request has been
	// written successfully and the call is awaiting a response (to be provided by
	// the readIncoming goroutine).

	call, err := NewCall(ac.id, method, params)
	if err != nil {
		ac.retire(&Response{ID: id, Error: fmt.Errorf("marshaling call parameters: %w", err)})
		return ac
	}

	c.updateInFlight(func(s *inFlightState) {
		err = s.shuttingDown(ErrClientClosing)
		if err != nil {
			return
		}
		if s.outgoingCalls == nil {
			s.outgoingCalls = make(map[ID]*AsyncCall)
		}
		s.outgoingCalls[ac.id] = ac
	})
	if err != nil {
		ac.retire(&Response{ID: id, Error: err})
		return ac
	}

	if err := c.write(ctx, call); err != nil {
		// Sending failed. We will never get a response, so deliver a fake one if it
		// wasn't already retired by the connection breaking.
		c.updateInFlight(func(s *inFlightState) {
			if s.outgoingCalls[ac.id] == ac {
				delete(s.outgoingCalls, ac.id)
				ac.retire(&Response{ID: id, Error: err})
			} else {
				// ac was already retired by the readIncoming goroutine:
				// perhaps our write raced with the Read side of the connection breaking.
			}
		})
	}
	return ac
}

type AsyncCall struct {
	id       ID
	ready    chan struct{} // closed after response has been set
	response *Response
}

// ID used for this call.
// This can be used to cancel the call if needed.
func (ac *AsyncCall) ID() ID { return ac.id }

// IsReady can be used to check if the result is already prepared.
// This is guaranteed to return true on a result for which Await has already
// returned, or a call that failed to send in the first place.
func (ac *AsyncCall) IsReady() bool {
	select {
	case <-ac.ready:
		return true
	default:
		return false
	}
}

// retire processes the response to the call.
func (ac *AsyncCall) retire(response *Response) {
	select {
	case <-ac.ready:
		panic(fmt.Sprintf("jsonrpc2: retire called twice for ID %v", ac.id))
	default:
	}

	ac.response = response
	close(ac.ready)
}

// Await waits for (and decodes) the results of a Call.
// The response will be unmarshaled from JSON into the result.
func (ac *AsyncCall) Await(ctx context.Context, result any) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	case <-ac.ready:
	}
	if ac.response.Error != nil {
		return ac.response.Error
	}
	if result == nil {
		return nil
	}
	return json.Unmarshal(ac.response.Result, result)
}

// Respond delivers a response to an incoming Call.
//
// Respond must be called exactly once for any message for which a handler
// returns ErrAsyncResponse. It must not be called for any other message.
func (c *Connection) Respond(id ID, result any, err error) error {
	var req *incomingRequest
	c.updateInFlight(func(s *inFlightState) {
		req = s.incomingByID[id]
	})
	if req == nil {
		return c.internalErrorf("Request not found for ID %v", id)
	}

	if err == ErrAsyncResponse {
		// Respond is supposed to supply the asynchronous response, so it would be
		// confusing to call Respond with an error that promises to call Respond
		// again.
		err = c.internalErrorf("Respond called with ErrAsyncResponse for %q", req.Method)
	}
	return c.processResult("Respond", req, result, err)
}

// Cancel cancels the Context passed to the Handle call for the inbound message
// with the given ID.
//
// Cancel will not complain if the ID is not a currently active message, and it
// will not cause any messages that have not arrived yet with that ID to be
// cancelled.
func (c *Connection) Cancel(id ID) {
	var req *incomingRequest
	c.updateInFlight(func(s *inFlightState) {
		req = s.incomingByID[id]
	})
	if req != nil {
		req.cancel()
	}
}

// Wait blocks until the connection is fully closed, but does not close it.
func (c *Connection) Wait() error {
	var err error
	<-c.done
	c.updateInFlight(func(s *inFlightState) {
		err = s.closeErr
	})
	return err
}

// Close stops accepting new requests, waits for in-flight requests and enqueued
// Handle calls to complete, and then closes the underlying stream.
//
// After the start of a Close, notification requests (that lack IDs and do not
// receive responses) will continue to be passed to the Preempter, but calls
// with IDs will receive immediate responses with ErrServerClosing, and no new
// requests (not even notifications!) will be enqueued to the Handler.
func (c *Connection) Close() error {
	// Stop handling new requests, and interrupt the reader (by closing the
	// connection) as soon as the active requests finish.
	c.updateInFlight(func(s *inFlightState) { s.connClosing = true })

	return c.Wait()
}

// readIncoming collects inbound messages from the reader and delivers them, either responding
// to outgoing calls or feeding requests to the queue.
func (c *Connection) readIncoming(ctx context.Context, reader Reader, preempter Preempter) {
	var err error
	for {
		var msg Message
		msg, err = reader.Read(ctx)
		if err != nil {
			break
		}

		switch msg := msg.(type) {
		case *Request:
			c.acceptRequest(ctx, msg, preempter)

		case *Response:
			c.updateInFlight(func(s *inFlightState) {
				if ac, ok := s.outgoingCalls[msg.ID]; ok {
					delete(s.outgoingCalls, msg.ID)
					ac.retire(msg)
				} else {
					// TODO: How should we report unexpected responses?
				}
			})

		default:
			c.internalErrorf("Read returned an unexpected message of type %T", msg)
		}
	}

	c.updateInFlight(func(s *inFlightState) {
		s.reading = false
		s.readErr = err

		// Retire any outgoing requests that were still in flight: with the Reader no
		// longer being processed, they necessarily cannot receive a response.
		for id, ac := range s.outgoingCalls {
			ac.retire(&Response{ID: id, Error: err})
		}
		s.outgoingCalls = nil
	})
}

// acceptRequest either handles msg synchronously or enqueues it to be handled
// asynchronously.
func (c *Connection) acceptRequest(ctx context.Context, msg *Request, preempter Preempter) {
	// In theory notifications cannot be cancelled, but we build them a cancel
	// context anyway.
	reqCtx, cancel := context.WithCancel(ctx)
	req := &incomingRequest{
		Request: msg,
		ctx:     reqCtx,
		cancel:  cancel,
	}

	// If the request is a call, add it to the incoming map so it can be
	// cancelled (or responded) by ID.
	var err error
	c.updateInFlight(func(s *inFlightState) {
		s.incoming++

		if req.IsCall() {
			if s.incomingByID[req.ID] != nil {
				err = fmt.Errorf("%w: request ID %v already in use", ErrInvalidRequest, req.ID)
				req.ID = ID{} // Don't misattribute this error to the existing request.
				return
			}

			if s.incomingByID == nil {
				s.incomingByID = make(map[ID]*incomingRequest)
			}
			s.incomingByID[req.ID] = req

			// When shutting down, reject all new Call requests, even if they could
			// theoretically be handled by the preempter. The preempter could return
			// ErrAsyncResponse, which would increase the amount of work in flight
			// when we're trying to ensure that it strictly decreases.
			err = s.shuttingDown(ErrServerClosing)
		}
	})
	if err != nil {
		c.processResult("acceptRequest", req, nil, err)
		return
	}

	if preempter != nil {
		result, err := preempter.Preempt(req.ctx, req.Request)

		if req.IsCall() && errors.Is(err, ErrAsyncResponse) {
			// This request will remain in flight until Respond is called for it.
			return
		}

		if !errors.Is(err, ErrNotHandled) {
			c.processResult("Preempt", req, result, err)
			return
		}
	}

	c.updateInFlight(func(s *inFlightState) {
		// If the connection is shutting down, don't enqueue anything to the
		// handler — not even notifications. That ensures that if the handler
		// continues to make progress, it will eventually become idle and
		// close the connection.
		err = s.shuttingDown(ErrServerClosing)
		if err != nil {
			return
		}

		// We enqueue requests that have not been preempted to an unbounded slice.
		// Unfortunately, we cannot in general limit the size of the handler
		// queue: we have to read every response that comes in on the wire
		// (because it may be responding to a request issued by, say, an
		// asynchronous handler), and in order to get to that response we have
		// to read all of the requests that came in ahead of it.
		s.handlerQueue = append(s.handlerQueue, req)
		if !s.handlerRunning {
			// We start the handleAsync goroutine when it has work to do, and let it
			// exit when the queue empties.
			//
			// Otherwise, in order to synchronize the handler we would need some other
			// goroutine (probably readIncoming?) to explicitly wait for handleAsync
			// to finish, and that would complicate error reporting: either the error
			// report from the goroutine would be blocked on the handler emptying its
			// queue (which was tried, and introduced a deadlock detected by
			// TestCloseCallRace), or the error would need to be reported separately
			// from synchronizing completion. Allowing the handler goroutine to exit
			// when idle seems simpler than trying to implement either of those
			// alternatives correctly.
			s.handlerRunning = true
			go c.handleAsync()
		}
	})
	if err != nil {
		c.processResult("acceptRequest", req, nil, err)
	}
}

// handleAsync invokes the handler on the requests in the handler queue
// sequentially until the queue is empty.
func (c *Connection) handleAsync() {
	for {
		var req *incomingRequest
		c.updateInFlight(func(s *inFlightState) {
			if len(s.handlerQueue) > 0 {
				req, s.handlerQueue = s.handlerQueue[0], s.handlerQueue[1:]
			} else {
				s.handlerRunning = false
			}
		})
		if req == nil {
			return
		}

		// Only deliver to the Handler if not already canceled.
		if err := req.ctx.Err(); err != nil {
			c.updateInFlight(func(s *inFlightState) {
				if s.writeErr != nil {
					// Assume that req.ctx was canceled due to s.writeErr.
					// TODO(#51365): use a Context API to plumb this through req.ctx.
					err = fmt.Errorf("%w: %v", ErrServerClosing, s.writeErr)
				}
			})
			c.processResult("handleAsync", req, nil, err)
			continue
		}

		result, err := c.handler.Handle(req.ctx, req.Request)
		c.processResult(c.handler, req, result, err)
	}
}

// processResult processes the result of a request and, if appropriate, sends a response.
func (c *Connection) processResult(from any, req *incomingRequest, result any, err error) error {
	switch err {
	case ErrAsyncResponse:
		if !req.IsCall() {
			return c.internalErrorf("%#v returned ErrAsyncResponse for a %q Request without an ID", from, req.Method)
		}
		return nil // This request is still in flight, so don't record the result yet.
	case ErrNotHandled, ErrMethodNotFound:
		// Add detail describing the unhandled method.
		err = fmt.Errorf("%w: %q", ErrMethodNotFound, req.Method)
	}

	if result != nil && err != nil {
		c.internalErrorf("%#v returned a non-nil result with a non-nil error for %s:\n%v\n%#v", from, req.Method, err, result)
		result = nil // Discard the spurious result and respond with err.
	}

	if req.IsCall() {
		if result == nil && err == nil {
			err = c.internalErrorf("%#v returned a nil result and nil error for a %q Request that requires a Response", from, req.Method)
		}

		response, respErr := NewResponse(req.ID, result, err)

		// The caller could theoretically reuse the request's ID as soon as we've
		// sent the response, so ensure that it is removed from the incoming map
		// before sending.
		c.updateInFlight(func(s *inFlightState) {
			delete(s.incomingByID, req.ID)
		})
		if respErr == nil {
			writeErr := c.write(notDone{req.ctx}, response)
			if err == nil {
				err = writeErr
			}
		} else {
			err = c.internalErrorf("%#v returned a malformed result for %q: %w", from, req.Method, respErr)
		}
	} else { // req is a notification
		if result != nil {
			err = c.internalErrorf("%#v returned a non-nil result for a %q Request without an ID", from, req.Method)
		} else if err != nil {
			err = fmt.Errorf("%w: %q notification failed: %v", ErrInternal, req.Method, err)
		}
		if err != nil {
			// TODO: can/should we do anything with this error beyond writing it to the event log?
			// (Is this the right label to attach to the log?)
		}
	}

	// Cancel the request to free any associated resources.
	req.cancel()
	c.updateInFlight(func(s *inFlightState) {
		if s.incoming == 0 {
			panic("jsonrpc2_v2: processResult called when incoming count is already zero")
		}
		s.incoming--
	})
	return nil
}

// write is used by all things that write outgoing messages, including replies.
// it makes sure that writes are atomic
func (c *Connection) write(ctx context.Context, msg Message) error {
	writer := <-c.writer
	defer func() { c.writer <- writer }()
	err := writer.Write(ctx, msg)

	if err != nil && ctx.Err() == nil {
		// The call to Write failed, and since ctx.Err() is nil we can't attribute
		// the failure (even indirectly) to Context cancellation. The writer appears
		// to be broken, and future writes are likely to also fail.
		//
		// If the read side of the connection is also broken, we might not even be
		// able to receive cancellation notifications. Since we can't reliably write
		// the results of incoming calls and can't receive explicit cancellations,
		// cancel the calls now.
		c.updateInFlight(func(s *inFlightState) {
			if s.writeErr == nil {
				s.writeErr = err
				for _, r := range s.incomingByID {
					r.cancel()
				}
			}
		})
	}

	return err
}

// internalErrorf reports an internal error. By default it panics, but if
// c.onInternalError is non-nil it instead calls that and returns an error
// wrapping ErrInternal.
func (c *Connection) internalErrorf(format string, args ...any) error {
	err := fmt.Errorf(format, args...)
	if c.onInternalError == nil {
		panic("jsonrpc2: " + err.Error())
	}
	c.onInternalError(err)

	return fmt.Errorf("%w: %v", ErrInternal, err)
}

// notDone is a context.Context wrapper that returns a nil Done channel.
type notDone struct{ ctx context.Context }

func (ic notDone) Value(key any) any {
	return ic.ctx.Value(key)
}

func (notDone) Done() <-chan struct{}       { return nil }
func (notDone) Err() error                  { return nil }
func (notDone) Deadline() (time.Time, bool) { return time.Time{}, false }


================================================
FILE: internal/jsonrpc2_v2/frame.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"strconv"
	"strings"
)

// Reader abstracts the transport mechanics from the JSON RPC protocol.
// A Conn reads messages from the reader it was provided on construction,
// and assumes that each call to Read fully transfers a single message,
// or returns an error.
// A reader is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Reader interface {
	// Read gets the next message from the stream.
	Read(context.Context) (Message, error)
}

// Writer abstracts the transport mechanics from the JSON RPC protocol.
// A Conn writes messages using the writer it was provided on construction,
// and assumes that each call to Write fully transfers a single message,
// or returns an error.
// A writer is not safe for concurrent use, it is expected it will be used by
// a single Conn in a safe manner.
type Writer interface {
	// Write sends a message to the stream.
	Write(context.Context, Message) error
}

// Framer wraps low level byte readers and writers into jsonrpc2 message
// readers and writers.
// It is responsible for the framing and encoding of messages into wire form.
//
// TODO(rfindley): rethink the framer interface, as with JSONRPC2 batching
// there is a need for Reader and Writer to be correlated, and while the
// implementation of framing here allows that, it is not made explicit by the
// interface.
//
// Perhaps a better interface would be
//
//	Frame(io.ReadWriteCloser) (Reader, Writer).
type Framer interface {
	// Reader wraps a byte reader into a message reader.
	Reader(io.Reader) Reader
	// Writer wraps a byte writer into a message writer.
	Writer(io.Writer) Writer
}

// RawFramer returns a new Framer.
// The messages are sent with no wrapping, and rely on json decode consistency
// to determine message boundaries.
func RawFramer() Framer { return rawFramer{} }

type rawFramer struct{}
type rawReader struct{ in *json.Decoder }
type rawWriter struct{ out io.Writer }

func (rawFramer) Reader(rw io.Reader) Reader {
	return &rawReader{in: json.NewDecoder(rw)}
}

func (rawFramer) Writer(rw io.Writer) Writer {
	return &rawWriter{out: rw}
}

func (r *rawReader) Read(ctx context.Context) (Message, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	default:
	}
	var raw json.RawMessage
	if err := r.in.Decode(&raw); err != nil {
		return nil, err
	}
	msg, err := DecodeMessage(raw)
	return msg, err
}

func (w *rawWriter) Write(ctx context.Context, msg Message) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}
	data, err := EncodeMessage(msg)
	if err != nil {
		return fmt.Errorf("marshaling message: %v", err)
	}
	_, err = w.out.Write(data)
	return err
}

// HeaderFramer returns a new Framer.
// The messages are sent with HTTP content length and MIME type headers.
// This is the format used by LSP and others.
func HeaderFramer() Framer { return headerFramer{} }

type headerFramer struct{}
type headerReader struct{ in *bufio.Reader }
type headerWriter struct{ out io.Writer }

func (headerFramer) Reader(rw io.Reader) Reader {
	return &headerReader{in: bufio.NewReader(rw)}
}

func (headerFramer) Writer(rw io.Writer) Writer {
	return &headerWriter{out: rw}
}

func (r *headerReader) Read(ctx context.Context) (Message, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	default:
	}

	firstRead := true // to detect a clean EOF below
	var contentLength int64
	// read the header, stop on the first empty line
	for {
		line, err := r.in.ReadString('\n')
		if err != nil {
			if err == io.EOF {
				if firstRead && line == "" {
					return nil, io.EOF // clean EOF
				}
				err = io.ErrUnexpectedEOF
			}
			return nil, fmt.Errorf("failed reading header line: %w", err)
		}
		firstRead = false

		line = strings.TrimSpace(line)
		// check we have a header line
		if line == "" {
			break
		}
		colon := strings.IndexRune(line, ':')
		if colon < 0 {
			return nil, fmt.Errorf("invalid header line %q", line)
		}
		name, value := line[:colon], strings.TrimSpace(line[colon+1:])
		switch name {
		case "Content-Length":
			if contentLength, err = strconv.ParseInt(value, 10, 32); err != nil {
				return nil, fmt.Errorf("failed parsing Content-Length: %v", value)
			}
			if contentLength <= 0 {
				return nil, fmt.Errorf("invalid Content-Length: %v", contentLength)
			}
		default:
			// ignoring unknown headers
		}
	}
	if contentLength == 0 {
		return nil, fmt.Errorf("missing Content-Length header")
	}
	data := make([]byte, contentLength)
	_, err := io.ReadFull(r.in, data)
	if err != nil {
		return nil, err
	}
	msg, err := DecodeMessage(data)
	return msg, err
}

func (w *headerWriter) Write(ctx context.Context, msg Message) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}
	data, err := EncodeMessage(msg)
	if err != nil {
		return fmt.Errorf("marshaling message: %v", err)
	}
	_, err = fmt.Fprintf(w.out, "Content-Length: %v\r\n\r\n", len(data))
	if err == nil {
		_, err = w.out.Write(data)
	}
	return err
}


================================================
FILE: internal/jsonrpc2_v2/jsonrpc2.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package jsonrpc2 is a minimal implementation of the JSON RPC 2 spec.
// https://www.jsonrpc.org/specification
// It is intended to be compatible with other implementations at the wire level.
package jsonrpc2

import (
	"context"
	"errors"
)

var (
	// ErrIdleTimeout is returned when serving timed out waiting for new connections.
	ErrIdleTimeout = errors.New("timed out waiting for new connections")

	// ErrNotHandled is returned from a Handler or Preempter to indicate it did
	// not handle the request.
	//
	// If a Handler returns ErrNotHandled, the server replies with
	// ErrMethodNotFound.
	ErrNotHandled = errors.New("JSON RPC not handled")

	// ErrAsyncResponse is returned from a handler to indicate it will generate a
	// response asynchronously.
	//
	// ErrAsyncResponse must not be returned for notifications,
	// which do not receive responses.
	ErrAsyncResponse = errors.New("JSON RPC asynchronous response")
)

// Preempter handles messages on a connection before they are queued to the main
// handler.
// Primarily this is used for cancel handlers or notifications for which out of
// order processing is not an issue.
type Preempter interface {
	// Preempt is invoked for each incoming request before it is queued for handling.
	//
	// If Preempt returns ErrNotHandled, the request will be queued,
	// and eventually passed to a Handle call.
	//
	// Otherwise, the result and error are processed as if returned by Handle.
	//
	// Preempt must not block. (The Context passed to it is for Values only.)
	Preempt(ctx context.Context, req *Request) (result any, err error)
}

// A PreempterFunc implements the Preempter interface for a standalone Preempt function.
type PreempterFunc func(ctx context.Context, req *Request) (any, error)

func (f PreempterFunc) Preempt(ctx context.Context, req *Request) (any, error) {
	return f(ctx, req)
}

var _ Preempter = PreempterFunc(nil)

// Handler handles messages on a connection.
type Handler interface {
	// Handle is invoked sequentially for each incoming request that has not
	// already been handled by a Preempter.
	//
	// If the Request has a nil ID, Handle must return a nil result,
	// and any error may be logged but will not be reported to the caller.
	//
	// If the Request has a non-nil ID, Handle must return either a
	// non-nil, JSON-marshalable result, or a non-nil error.
	//
	// The Context passed to Handle will be canceled if the
	// connection is broken or the request is canceled or completed.
	// (If Handle returns ErrAsyncResponse, ctx will remain uncanceled
	// until either Cancel or Respond is called for the request's ID.)
	Handle(ctx context.Context, req *Request) (result any, err error)
}

type defaultHandler struct{}

func (defaultHandler) Preempt(context.Context, *Request) (any, error) {
	return nil, ErrNotHandled
}

func (defaultHandler) Handle(context.Context, *Request) (any, error) {
	return nil, ErrNotHandled
}

// A HandlerFunc implements the Handler interface for a standalone Handle function.
type HandlerFunc func(ctx context.Context, req *Request) (any, error)

func (f HandlerFunc) Handle(ctx context.Context, req *Request) (any, error) {
	return f(ctx, req)
}

var _ Handler = HandlerFunc(nil)

// async is a small helper for operations with an asynchronous result that you
// can wait for.
type async struct {
	ready    chan struct{} // closed when done
	firstErr chan error    // 1-buffered; contains either nil or the first non-nil error
}

func newAsync() *async {
	var a async
	a.ready = make(chan struct{})
	a.firstErr = make(chan error, 1)
	a.firstErr <- nil
	return &a
}

func (a *async) done() {
	close(a.ready)
}

func (a *async) wait() error {
	<-a.ready
	err := <-a.firstErr
	a.firstErr <- err
	return err
}

func (a *async) setError(err error) {
	storedErr := <-a.firstErr
	if storedErr == nil {
		storedErr = err
	}
	a.firstErr <- storedErr
}


================================================
FILE: internal/jsonrpc2_v2/jsonrpc2_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2_test

import (
	"context"
	"encoding/json"
	"fmt"
	"path"
	"reflect"
	"testing"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

var callTests = []invoker{
	call{"no_args", nil, true},
	call{"one_string", "fish", "got:fish"},
	call{"one_number", 10, "got:10"},
	call{"join", []string{"a", "b", "c"}, "a/b/c"},
	sequence{"notify", []invoker{
		notify{"set", 3},
		notify{"add", 5},
		call{"get", nil, 8},
	}},
	sequence{"preempt", []invoker{
		async{"a", "wait", "a"},
		notify{"unblock", "a"},
		collect{"a", true, false},
	}},
	sequence{"basic cancel", []invoker{
		async{"b", "wait", "b"},
		cancel{"b"},
		collect{"b", nil, true},
	}},
	sequence{"queue", []invoker{
		async{"a", "wait", "a"},
		notify{"set", 1},
		notify{"add", 2},
		notify{"add", 3},
		notify{"add", 4},
		call{"peek", nil, 0}, // accumulator will not have any adds yet
		notify{"unblock", "a"},
		collect{"a", true, false},
		call{"get", nil, 10}, // accumulator now has all the adds
	}},
	sequence{"fork", []invoker{
		async{"a", "fork", "a"},
		notify{"set", 1},
		notify{"add", 2},
		notify{"add", 3},
		notify{"add", 4},
		call{"get", nil, 10}, // fork will not have blocked the adds
		notify{"unblock", "a"},
		collect{"a", true, false},
	}},
	sequence{"concurrent", []invoker{
		async{"a", "fork", "a"},
		notify{"unblock", "a"},
		async{"b", "fork", "b"},
		notify{"unblock", "b"},
		collect{"a", true, false},
		collect{"b", true, false},
	}},
}

type binder struct {
	framer  jsonrpc2.Framer
	runTest func(*handler)
}

type handler struct {
	conn        *jsonrpc2.Connection
	accumulator int
	waiters     chan map[string]chan struct{}
	calls       map[string]*jsonrpc2.AsyncCall
}

type invoker interface {
	Name() string
	Invoke(t *testing.T, ctx context.Context, h *handler)
}

type notify struct {
	method string
	params any
}

type call struct {
	method string
	params any
	expect any
}

type async struct {
	name   string
	method string
	params any
}

type collect struct {
	name   string
	expect any
	fails  bool
}

type cancel struct {
	name string
}

type sequence struct {
	name  string
	tests []invoker
}

type echo call

type cancelParams struct{ ID int64 }

func TestConnectionRaw(t *testing.T) {
	testConnection(t, jsonrpc2.RawFramer())
}

func TestConnectionHeader(t *testing.T) {
	testConnection(t, jsonrpc2.HeaderFramer())
}

func testConnection(t *testing.T, framer jsonrpc2.Framer) {
	ctx := context.Background()
	listener, err := jsonrpc2.NetPipeListener(ctx)
	if err != nil {
		t.Fatal(err)
	}
	server := jsonrpc2.NewServer(ctx, listener, binder{framer, nil})
	defer func() {
		listener.Close()
		server.Wait()
	}()

	for _, test := range callTests {
		t.Run(test.Name(), func(t *testing.T) {
			client, err := jsonrpc2.Dial(ctx,
				listener.Dialer(), binder{framer, func(h *handler) {
					defer h.conn.Close()
					test.Invoke(t, ctx, h)
					if call, ok := test.(*call); ok {
						// also run all simple call tests in echo mode
						(*echo)(call).Invoke(t, ctx, h)
					}
				}}, nil)
			if err != nil {
				t.Fatal(err)
			}
			client.Wait()
		})
	}
}

func (test notify) Name() string { return test.method }
func (test notify) Invoke(t *testing.T, ctx context.Context, h *handler) {
	if err := h.conn.Notify(ctx, test.method, test.params); err != nil {
		t.Fatalf("%v:Notify failed: %v", test.method, err)
	}
}

func (test call) Name() string { return test.method }
func (test call) Invoke(t *testing.T, ctx context.Context, h *handler) {
	results := newResults(test.expect)
	if err := h.conn.Call(ctx, test.method, test.params).Await(ctx, results); err != nil {
		t.Fatalf("%v:Call failed: %v", test.method, err)
	}
	verifyResults(t, test.method, results, test.expect)
}

func (test echo) Invoke(t *testing.T, ctx context.Context, h *handler) {
	results := newResults(test.expect)
	if err := h.conn.Call(ctx, "echo", []any{test.method, test.params}).Await(ctx, results); err != nil {
		t.Fatalf("%v:Echo failed: %v", test.method, err)
	}
	verifyResults(t, test.method, results, test.expect)
}

func (test async) Name() string { return test.name }
func (test async) Invoke(t *testing.T, ctx context.Context, h *handler) {
	h.calls[test.name] = h.conn.Call(ctx, test.method, test.params)
}

func (test collect) Name() string { return test.name }
func (test collect) Invoke(t *testing.T, ctx context.Context, h *handler) {
	o := h.calls[test.name]
	results := newResults(test.expect)
	err := o.Await(ctx, results)
	switch {
	case test.fails && err == nil:
		t.Fatalf("%v:Collect was supposed to fail", test.name)
	case !test.fails && err != nil:
		t.Fatalf("%v:Collect failed: %v", test.name, err)
	}
	verifyResults(t, test.name, results, test.expect)
}

func (test cancel) Name() string { return test.name }
func (test cancel) Invoke(t *testing.T, ctx context.Context, h *handler) {
	o := h.calls[test.name]
	if err := h.conn.Notify(ctx, "cancel", &cancelParams{o.ID().Raw().(int64)}); err != nil {
		t.Fatalf("%v:Collect failed: %v", test.name, err)
	}
}

func (test sequence) Name() string { return test.name }
func (test sequence) Invoke(t *testing.T, ctx context.Context, h *handler) {
	for _, child := range test.tests {
		child.Invoke(t, ctx, h)
	}
}

// newResults makes a new empty copy of the expected type to put the results into
func newResults(expect any) any {
	switch e := expect.(type) {
	case []any:
		var r []any
		for _, v := range e {
			r = append(r, reflect.New(reflect.TypeOf(v)).Interface())
		}
		return r
	case nil:
		return nil
	default:
		return reflect.New(reflect.TypeOf(expect)).Interface()
	}
}

// verifyResults compares the results to the expected values
func verifyResults(t *testing.T, method string, results any, expect any) {
	if expect == nil {
		if results != nil {
			t.Errorf("%v:Got results %+v where none expected", method, expect)
		}
		return
	}
	val := reflect.Indirect(reflect.ValueOf(results)).Interface()
	if !reflect.DeepEqual(val, expect) {
		t.Errorf("%v:Results are incorrect, got %+v expect %+v", method, val, expect)
	}
}

func (b binder) Bind(ctx context.Context, conn *jsonrpc2.Connection) jsonrpc2.ConnectionOptions {
	h := &handler{
		conn:    conn,
		waiters: make(chan map[string]chan struct{}, 1),
		calls:   make(map[string]*jsonrpc2.AsyncCall),
	}
	h.waiters <- make(map[string]chan struct{})
	if b.runTest != nil {
		go b.runTest(h)
	}
	return jsonrpc2.ConnectionOptions{
		Framer:    b.framer,
		Preempter: h,
		Handler:   h,
	}
}

func (h *handler) waiter(name string) chan struct{} {
	waiters := <-h.waiters
	defer func() { h.waiters <- waiters }()
	waiter, found := waiters[name]
	if !found {
		waiter = make(chan struct{})
		waiters[name] = waiter
	}
	return waiter
}

func (h *handler) Preempt(ctx context.Context, req *jsonrpc2.Request) (any, error) {
	switch req.Method {
	case "unblock":
		var name string
		if err := json.Unmarshal(req.Params, &name); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		close(h.waiter(name))
		return nil, nil
	case "peek":
		if len(req.Params) > 0 {
			return nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams)
		}
		return h.accumulator, nil
	case "cancel":
		var params cancelParams
		if err := json.Unmarshal(req.Params, &params); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		h.conn.Cancel(jsonrpc2.Int64ID(params.ID))
		return nil, nil
	default:
		return nil, jsonrpc2.ErrNotHandled
	}
}

func (h *handler) Handle(ctx context.Context, req *jsonrpc2.Request) (any, error) {
	switch req.Method {
	case "no_args":
		if len(req.Params) > 0 {
			return nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams)
		}
		return true, nil
	case "one_string":
		var v string
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		return "got:" + v, nil
	case "one_number":
		var v int
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		return fmt.Sprintf("got:%d", v), nil
	case "set":
		var v int
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		h.accumulator = v
		return nil, nil
	case "add":
		var v int
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		h.accumulator += v
		return nil, nil
	case "get":
		if len(req.Params) > 0 {
			return nil, fmt.Errorf("%w: expected no params", jsonrpc2.ErrInvalidParams)
		}
		return h.accumulator, nil
	case "join":
		var v []string
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		return path.Join(v...), nil
	case "echo":
		var v []any
		if err := json.Unmarshal(req.Params, &v); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		var result any
		err := h.conn.Call(ctx, v[0].(string), v[1]).Await(ctx, &result)
		return result, err
	case "wait":
		var name string
		if err := json.Unmarshal(req.Params, &name); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		select {
		case <-h.waiter(name):
			return true, nil
		case <-ctx.Done():
			return nil, ctx.Err()
		}
	case "fork":
		var name string
		if err := json.Unmarshal(req.Params, &name); err != nil {
			return nil, fmt.Errorf("%w: %s", jsonrpc2.ErrParse, err)
		}
		waitFor := h.waiter(name)
		go func() {
			select {
			case <-waitFor:
				h.conn.Respond(req.ID, true, nil)
			case <-ctx.Done():
				h.conn.Respond(req.ID, nil, ctx.Err())
			}
		}()
		return nil, jsonrpc2.ErrAsyncResponse
	default:
		return nil, jsonrpc2.ErrNotHandled
	}
}


================================================
FILE: internal/jsonrpc2_v2/messages.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"encoding/json"
	"errors"
	"fmt"
)

// ID is a Request identifier, which is defined by the spec to be a string, integer, or null.
// https://www.jsonrpc.org/specification#request_object
type ID struct {
	value any
}

// MakeID coerces the given Go value to an ID. The value is assumed to be the
// default JSON marshaling of a Request identifier -- nil, float64, or string.
//
// Returns an error if the value type was a valid Request ID type.
//
// TODO: ID can't be a json.Marshaler/Unmarshaler, because we want to omitzero.
// Simplify this package by making ID json serializable once we can rely on
// omitzero.
func MakeID(v any) (ID, error) {
	switch v := v.(type) {
	case nil:
		return ID{}, nil
	case float64:
		return Int64ID(int64(v)), nil
	case string:
		return StringID(v), nil
	}
	return ID{}, fmt.Errorf("%w: invalid ID type %T", ErrParse, v)
}

// Message is the interface to all jsonrpc2 message types.
// They share no common functionality, but are a closed set of concrete types
// that are allowed to implement this interface. The message types are *Request
// and *Response.
type Message interface {
	// marshal builds the wire form from the API form.
	// It is private, which makes the set of Message implementations closed.
	marshal(to *wireCombined)
}

// Request is a Message sent to a peer to request behavior.
// If it has an ID it is a call, otherwise it is a notification.
type Request struct {
	// ID of this request, used to tie the Response back to the request.
	// This will be nil for notifications.
	ID ID
	// Method is a string containing the method name to invoke.
	Method string
	// Params is either a struct or an array with the parameters of the method.
	Params json.RawMessage
}

// Response is a Message used as a reply to a call Request.
// It will have the same ID as the call it is a response to.
type Response struct {
	// result is the content of the response.
	Result json.RawMessage
	// err is set only if the call failed.
	Error error
	// id of the request this is a response to.
	ID ID
}

// StringID creates a new string request identifier.
func StringID(s string) ID { return ID{value: s} }

// Int64ID creates a new integer request identifier.
func Int64ID(i int64) ID { return ID{value: i} }

// IsValid returns true if the ID is a valid identifier.
// The default value for ID will return false.
func (id ID) IsValid() bool { return id.value != nil }

// Raw returns the underlying value of the ID.
func (id ID) Raw() any { return id.value }

// NewNotification constructs a new Notification message for the supplied
// method and parameters.
func NewNotification(method string, params any) (*Request, error) {
	p, merr := marshalToRaw(params)
	return &Request{Method: method, Params: p}, merr
}

// NewCall constructs a new Call message for the supplied ID, method and
// parameters.
func NewCall(id ID, method string, params any) (*Request, error) {
	p, merr := marshalToRaw(params)
	return &Request{ID: id, Method: method, Params: p}, merr
}

func (msg *Request) IsCall() bool { return msg.ID.IsValid() }

func (msg *Request) marshal(to *wireCombined) {
	to.ID = msg.ID.value
	to.Method = msg.Method
	to.Params = msg.Params
}

// NewResponse constructs a new Response message that is a reply to the
// supplied. If err is set result may be ignored.
func NewResponse(id ID, result any, rerr error) (*Response, error) {
	r, merr := marshalToRaw(result)
	return &Response{ID: id, Result: r, Error: rerr}, merr
}

func (msg *Response) marshal(to *wireCombined) {
	to.ID = msg.ID.value
	to.Error = toWireError(msg.Error)
	to.Result = msg.Result
}

func toWireError(err error) *WireError {
	if err == nil {
		// no error, the response is complete
		return nil
	}
	if err, ok := err.(*WireError); ok {
		// already a wire error, just use it
		return err
	}
	result := &WireError{Message: err.Error()}
	var wrapped *WireError
	if errors.As(err, &wrapped) {
		// if we wrapped a wire error, keep the code from the wrapped error
		// but the message from the outer error
		result.Code = wrapped.Code
	}
	return result
}

func EncodeMessage(msg Message) ([]byte, error) {
	wire := wireCombined{VersionTag: wireVersion}
	msg.marshal(&wire)
	data, err := json.Marshal(&wire)
	if err != nil {
		return data, fmt.Errorf("marshaling jsonrpc message: %w", err)
	}
	return data, nil
}

// EncodeIndent is like EncodeMessage, but honors indents.
// TODO(rfindley): refactor so that this concern is handled independently.
// Perhaps we should pass in a json.Encoder?
func EncodeIndent(msg Message, prefix, indent string) ([]byte, error) {
	wire := wireCombined{VersionTag: wireVersion}
	msg.marshal(&wire)
	data, err := json.MarshalIndent(&wire, prefix, indent)
	if err != nil {
		return data, fmt.Errorf("marshaling jsonrpc message: %w", err)
	}
	return data, nil
}

func DecodeMessage(data []byte) (Message, error) {
	msg := wireCombined{}
	if err := json.Unmarshal(data, &msg); err != nil {
		return nil, fmt.Errorf("unmarshaling jsonrpc message: %w", err)
	}
	if msg.VersionTag != wireVersion {
		return nil, fmt.Errorf("invalid message version tag %q; expected %q", msg.VersionTag, wireVersion)
	}
	id, err := MakeID(msg.ID)
	if err != nil {
		return nil, err
	}
	if msg.Method != "" {
		// has a method, must be a call
		return &Request{
			Method: msg.Method,
			ID:     id,
			Params: msg.Params,
		}, nil
	}
	// no method, should be a response
	if !id.IsValid() {
		return nil, ErrInvalidRequest
	}
	resp := &Response{
		ID:     id,
		Result: msg.Result,
	}
	// we have to check if msg.Error is nil to avoid a typed error
	if msg.Error != nil {
		resp.Error = msg.Error
	}
	return resp, nil
}

func marshalToRaw(obj any) (json.RawMessage, error) {
	if obj == nil {
		return nil, nil
	}
	data, err := json.Marshal(obj)
	if err != nil {
		return nil, err
	}
	return json.RawMessage(data), nil
}


================================================
FILE: internal/jsonrpc2_v2/net.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"io"
	"net"
	"os"
)

// This file contains implementations of the transport primitives that use the standard network
// package.

// NetListenOptions is the optional arguments to the NetListen function.
type NetListenOptions struct {
	NetListenConfig net.ListenConfig
	NetDialer       net.Dialer
}

// NetListener returns a new Listener that listens on a socket using the net package.
func NetListener(ctx context.Context, network, address string, options NetListenOptions) (Listener, error) {
	ln, err := options.NetListenConfig.Listen(ctx, network, address)
	if err != nil {
		return nil, err
	}
	return &netListener{net: ln}, nil
}

// netListener is the implementation of Listener for connections made using the net package.
type netListener struct {
	net net.Listener
}

// Accept blocks waiting for an incoming connection to the listener.
func (l *netListener) Accept(context.Context) (io.ReadWriteCloser, error) {
	return l.net.Accept()
}

// Close will cause the listener to stop listening. It will not close any connections that have
// already been accepted.
func (l *netListener) Close() error {
	addr := l.net.Addr()
	err := l.net.Close()
	if addr.Network() == "unix" {
		rerr := os.Remove(addr.String())
		if rerr != nil && err == nil {
			err = rerr
		}
	}
	return err
}

// Dialer returns a dialer that can be used to connect to the listener.
func (l *netListener) Dialer() Dialer {
	return NetDialer(l.net.Addr().Network(), l.net.Addr().String(), net.Dialer{})
}

// NetDialer returns a Dialer using the supplied standard network dialer.
func NetDialer(network, address string, nd net.Dialer) Dialer {
	return &netDialer{
		network: network,
		address: address,
		dialer:  nd,
	}
}

type netDialer struct {
	network string
	address string
	dialer  net.Dialer
}

func (n *netDialer) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
	return n.dialer.DialContext(ctx, n.network, n.address)
}

// NetPipeListener returns a new Listener that listens using net.Pipe.
// It is only possibly to connect to it using the Dialer returned by the
// Dialer method, each call to that method will generate a new pipe the other
// side of which will be returned from the Accept call.
func NetPipeListener(ctx context.Context) (Listener, error) {
	return &netPiper{
		done:   make(chan struct{}),
		dialed: make(chan io.ReadWriteCloser),
	}, nil
}

// netPiper is the implementation of Listener build on top of net.Pipes.
type netPiper struct {
	done   chan struct{}
	dialed chan io.ReadWriteCloser
}

// Accept blocks waiting for an incoming connection to the listener.
func (l *netPiper) Accept(context.Context) (io.ReadWriteCloser, error) {
	// Block until the pipe is dialed or the listener is closed,
	// preferring the latter if already closed at the start of Accept.
	select {
	case <-l.done:
		return nil, net.ErrClosed
	default:
	}
	select {
	case rwc := <-l.dialed:
		return rwc, nil
	case <-l.done:
		return nil, net.ErrClosed
	}
}

// Close will cause the listener to stop listening. It will not close any connections that have
// already been accepted.
func (l *netPiper) Close() error {
	// unblock any accept calls that are pending
	close(l.done)
	return nil
}

func (l *netPiper) Dialer() Dialer {
	return l
}

func (l *netPiper) Dial(ctx context.Context) (io.ReadWriteCloser, error) {
	client, server := net.Pipe()

	select {
	case l.dialed <- server:
		return client, nil

	case <-l.done:
		client.Close()
		server.Close()
		return nil, net.ErrClosed
	}
}


================================================
FILE: internal/jsonrpc2_v2/serve.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"context"
	"fmt"
	"io"
	"runtime"
	"sync"
	"sync/atomic"
	"time"
)

// Listener is implemented by protocols to accept new inbound connections.
type Listener interface {
	// Accept accepts an inbound connection to a server.
	// It blocks until either an inbound connection is made, or the listener is closed.
	Accept(context.Context) (io.ReadWriteCloser, error)

	// Close closes the listener.
	// Any blocked Accept or Dial operations will unblock and return errors.
	Close() error

	// Dialer returns a dialer that can be used to connect to this listener
	// locally.
	// If a listener does not implement this it will return nil.
	Dialer() Dialer
}

// Dialer is used by clients to dial a server.
type Dialer interface {
	// Dial returns a new communication byte stream to a listening server.
	Dial(ctx context.Context) (io.ReadWriteCloser, error)
}

// Server is a running server that is accepting incoming connections.
type Server struct {
	listener Listener
	binder   Binder
	async    *async

	shutdownOnce sync.Once
	closing      int32 // atomic: set to nonzero when Shutdown is called
}

// Dial uses the dialer to make a new connection, wraps the returned
// reader and writer using the framer to make a stream, and then builds
// a connection on top of that stream using the binder.
//
// The returned Connection will operate independently using the Preempter and/or
// Handler provided by the Binder, and will release its own resources when the
// connection is broken, but the caller may Close it earlier to stop accepting
// (or sending) new requests.
//
// If non-nil, the onDone function is called when the connection is closed.
func Dial(ctx context.Context, dialer Dialer, binder Binder, onDone func()) (*Connection, error) {
	// dial a server
	rwc, err := dialer.Dial(ctx)
	if err != nil {
		return nil, err
	}
	return bindConnection(ctx, rwc, binder, onDone), nil
}

// NewServer starts a new server listening for incoming connections and returns
// it.
// This returns a fully running and connected server, it does not block on
// the listener.
// You can call Wait to block on the server, or Shutdown to get the sever to
// terminate gracefully.
// To notice incoming connections, use an intercepting Binder.
func NewServer(ctx context.Context, listener Listener, binder Binder) *Server {
	server := &Server{
		listener: listener,
		binder:   binder,
		async:    newAsync(),
	}
	go server.run(ctx)
	return server
}

// Wait returns only when the server has shut down.
func (s *Server) Wait() error {
	return s.async.wait()
}

// Shutdown informs the server to stop accepting new connections.
func (s *Server) Shutdown() {
	s.shutdownOnce.Do(func() {
		atomic.StoreInt32(&s.closing, 1)
		s.listener.Close()
	})
}

// run accepts incoming connections from the listener,
// If IdleTimeout is non-zero, run exits after there are no clients for this
// duration, otherwise it exits only on error.
func (s *Server) run(ctx context.Context) {
	defer s.async.done()

	var activeConns sync.WaitGroup
	for {
		rwc, err := s.listener.Accept(ctx)
		if err != nil {
			// Only Shutdown closes the listener. If we get an error after Shutdown is
			// called, assume that was the cause and don't report the error;
			// otherwise, report the error in case it is unexpected.
			if atomic.LoadInt32(&s.closing) == 0 {
				s.async.setError(err)
			}
			// We are done generating new connections for good.
			break
		}

		// A new inbound connection.
		activeConns.Add(1)
		_ = bindConnection(ctx, rwc, s.binder, activeConns.Done) // unregisters itself when done
	}
	activeConns.Wait()
}

// NewIdleListener wraps a listener with an idle timeout.
//
// When there are no active connections for at least the timeout duration,
// calls to Accept will fail with ErrIdleTimeout.
//
// A connection is considered inactive as soon as its Close method is called.
func NewIdleListener(timeout time.Duration, wrap Listener) Listener {
	l := &idleListener{
		wrapped:   wrap,
		timeout:   timeout,
		active:    make(chan int, 1),
		timedOut:  make(chan struct{}),
		idleTimer: make(chan *time.Timer, 1),
	}
	l.idleTimer <- time.AfterFunc(l.timeout, l.timerExpired)
	return l
}

type idleListener struct {
	wrapped Listener
	timeout time.Duration

	// Only one of these channels is receivable at any given time.
	active    chan int         // count of active connections; closed when Close is called if not timed out
	timedOut  chan struct{}    // closed when the idle timer expires
	idleTimer chan *time.Timer // holds the timer only when idle
}

// Accept accepts an incoming connection.
//
// If an incoming connection is accepted concurrent to the listener being closed
// due to idleness, the new connection is immediately closed.
func (l *idleListener) Accept(ctx context.Context) (io.ReadWriteCloser, error) {
	rwc, err := l.wrapped.Accept(ctx)

	select {
	case n, ok := <-l.active:
		if err != nil {
			if ok {
				l.active <- n
			}
			return nil, err
		}
		if ok {
			l.active <- n + 1
		} else {
			// l.wrapped.Close Close has been called, but Accept returned a
			// connection. This race can occur with concurrent Accept and Close calls
			// with any net.Listener, and it is benign: since the listener was closed
			// explicitly, it can't have also timed out.
		}
		return l.newConn(rwc), nil

	case <-l.timedOut:
		if err == nil {
			// Keeping the connection open would leave the listener simultaneously
			// active and closed due to idleness, which would be contradictory and
			// confusing. Close the connection and pretend that it never happened.
			rwc.Close()
		} else {
			// In theory the timeout could have raced with an unrelated error return
			// from Accept. However, ErrIdleTimeout is arguably still valid (since we
			// would have closed due to the timeout independent of the error), and the
			// harm from returning a spurious ErrIdleTimeout is negligible anyway.
		}
		return nil, ErrIdleTimeout

	case timer := <-l.idleTimer:
		if err != nil {
			// The idle timer doesn't run until it receives itself from the idleTimer
			// channel, so it can't have called l.wrapped.Close yet and thus err can't
			// be ErrIdleTimeout. Leave the idle timer as it was and return whatever
			// error we got.
			l.idleTimer <- timer
			return nil, err
		}

		if !timer.Stop() {
			// Failed to stop the timer — the timer goroutine is in the process of
			// firing. Send the timer back to the timer goroutine so that it can
			// safely close the timedOut channel, and then wait for the listener to
			// actually be closed before we return ErrIdleTimeout.
			l.idleTimer <- timer
			rwc.Close()
			<-l.timedOut
			return nil, ErrIdleTimeout
		}

		l.active <- 1
		return l.newConn(rwc), nil
	}
}

func (l *idleListener) Close() error {
	select {
	case _, ok := <-l.active:
		if ok {
			close(l.active)
		}

	case <-l.timedOut:
		// Already closed by the timer; take care not to double-close if the caller
		// only explicitly invokes this Close method once, since the io.Closer
		// interface explicitly leaves doubled Close calls undefined.
		return ErrIdleTimeout

	case timer := <-l.idleTimer:
		if !timer.Stop() {
			// Couldn't stop the timer. It shouldn't take long to run, so just wait
			// (so that the Listener is guaranteed to be closed before we return)
			// and pretend that this call happened afterward.
			// That way we won't leak any timers or goroutines when Close returns.
			l.idleTimer <- timer
			<-l.timedOut
			return ErrIdleTimeout
		}
		close(l.active)
	}

	return l.wrapped.Close()
}

func (l *idleListener) Dialer() Dialer {
	return l.wrapped.Dialer()
}

func (l *idleListener) timerExpired() {
	select {
	case n, ok := <-l.active:
		if ok {
			panic(fmt.Sprintf("jsonrpc2: idleListener idle timer fired with %d connections still active", n))
		} else {
			panic("jsonrpc2: Close finished with idle timer still running")
		}

	case <-l.timedOut:
		panic("jsonrpc2: idleListener idle timer fired more than once")

	case <-l.idleTimer:
		// The timer for this very call!
	}

	// Close the Listener with all channels still blocked to ensure that this call
	// to l.wrapped.Close doesn't race with the one in l.Close.
	defer close(l.timedOut)
	l.wrapped.Close()
}

func (l *idleListener) connClosed() {
	select {
	case n, ok := <-l.active:
		if !ok {
			// l is already closed, so it can't close due to idleness,
			// and we don't need to track the number of active connections any more.
			return
		}
		n--
		if n == 0 {
			l.idleTimer <- time.AfterFunc(l.timeout, l.timerExpired)
		} else {
			l.active <- n
		}

	case <-l.timedOut:
		panic("jsonrpc2: idleListener idle timer fired before last active connection was closed")

	case <-l.idleTimer:
		panic("jsonrpc2: idleListener idle timer active before last active connection was closed")
	}
}

type idleListenerConn struct {
	wrapped   io.ReadWriteCloser
	l         *idleListener
	closeOnce sync.Once
}

func (l *idleListener) newConn(rwc io.ReadWriteCloser) *idleListenerConn {
	c := &idleListenerConn{
		wrapped: rwc,
		l:       l,
	}

	// A caller that forgets to call Close may disrupt the idleListener's
	// accounting, even though the file descriptor for the underlying connection
	// may eventually be garbage-collected anyway.
	//
	// Set a (best-effort) finalizer to verify that a Close call always occurs.
	// (We will clear the finalizer explicitly in Close.)
	runtime.SetFinalizer(c, func(c *idleListenerConn) {
		panic("jsonrpc2: IdleListener connection became unreachable without a call to Close")
	})

	return c
}

func (c *idleListenerConn) Read(p []byte) (int, error)  { return c.wrapped.Read(p) }
func (c *idleListenerConn) Write(p []byte) (int, error) { return c.wrapped.Write(p) }

func (c *idleListenerConn) Close() error {
	defer c.closeOnce.Do(func() {
		c.l.connClosed()
		runtime.SetFinalizer(c, nil)
	})
	return c.wrapped.Close()
}


================================================
FILE: internal/jsonrpc2_v2/serve_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2_test

import (
	"context"
	"errors"
	"fmt"
	"runtime"
	"runtime/debug"
	"testing"
	"time"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

// needsLocalhostNet skips t if networking does not work for ports opened
// with "localhost".
// forked from golang.org/x/tools/internal/testenv.
func needsLocalhostNet(t testing.TB) {
	switch runtime.GOOS {
	case "js", "wasip1":
		t.Skipf(`Listening on "localhost" fails on %s; see https://go.dev/issue/59718`, runtime.GOOS)
	}
}

func TestIdleTimeout(t *testing.T) {
	needsLocalhostNet(t)

	// Use a panicking time.AfterFunc instead of context.WithTimeout so that we
	// get a goroutine dump on failure. We expect the test to take on the order of
	// a few tens of milliseconds at most, so 10s should be several orders of
	// magnitude of headroom.
	timer := time.AfterFunc(10*time.Second, func() {
		debug.SetTraceback("all")
		panic("TestIdleTimeout deadlocked")
	})
	defer timer.Stop()

	ctx := context.Background()

	try := func(d time.Duration) (longEnough bool) {
		listener, err := jsonrpc2.NetListener(ctx, "tcp", "localhost:0", jsonrpc2.NetListenOptions{})
		if err != nil {
			t.Fatal(err)
		}

		idleStart := time.Now()
		listener = jsonrpc2.NewIdleListener(d, listener)
		defer listener.Close()

		server := jsonrpc2.NewServer(ctx, listener, jsonrpc2.ConnectionOptions{})

		// Exercise some connection/disconnection patterns, and then assert that when
		// our timer fires, the server exits.
		conn1, err := jsonrpc2.Dial(ctx, listener.Dialer(), jsonrpc2.ConnectionOptions{}, nil)
		if err != nil {
			if since := time.Since(idleStart); since < d {
				t.Fatalf("conn1 failed to connect after %v: %v", since, err)
			}
			t.Log("jsonrpc2.Dial:", err)
			return false // Took to long to dial, so the failure could have been due to the idle timeout.
		}
		// On the server side, Accept can race with the connection timing out.
		// Send a call and wait for the response to ensure that the connection was
		// actually fully accepted.
		ac := conn1.Call(ctx, "ping", nil)
		if err := ac.Await(ctx, nil); !errors.Is(err, jsonrpc2.ErrMethodNotFound) {
			if since := time.Since(idleStart); since < d {
				t.Fatalf("conn1 broken after %v: %v", since, err)
			}
			t.Log(`conn1.Call(ctx, "ping", nil):`, err)
			conn1.Close()
			return false
		}

		// Since conn1 was successfully accepted and remains open, the server is
		// definitely non-idle. Dialing another simultaneous connection should
		// succeed.
		conn2, err := jsonrpc2.Dial(ctx, listener.Dialer(), jsonrpc2.ConnectionOptions{}, nil)
		if err != nil {
			conn1.Close()
			t.Fatalf("conn2 failed to connect while non-idle after %v: %v", time.Since(idleStart), err)
			return false
		}
		// Ensure that conn2 is also accepted on the server side before we close
		// conn1. Otherwise, the connection can appear idle if the server processes
		// the closure of conn1 and the idle timeout before it finally notices conn2
		// in the accept queue.
		// (That failure mode may explain the failure noted in
		// https://go.dev/issue/49387#issuecomment-1303979877.)
		ac = conn2.Call(ctx, "ping", nil)
		if err := ac.Await(ctx, nil); !errors.Is(err, jsonrpc2.ErrMethodNotFound) {
			t.Fatalf("conn2 broken while non-idle after %v: %v", time.Since(idleStart), err)
		}

		if err := conn1.Close(); err != nil {
			t.Fatalf("conn1.Close failed with error: %v", err)
		}
		idleStart = time.Now()
		if err := conn2.Close(); err != nil {
			t.Fatalf("conn2.Close failed with error: %v", err)
		}

		conn3, err := jsonrpc2.Dial(ctx, listener.Dialer(), jsonrpc2.ConnectionOptions{}, nil)
		if err != nil {
			if since := time.Since(idleStart); since < d {
				t.Fatalf("conn3 failed to connect after %v: %v", since, err)
			}
			t.Log("jsonrpc2.Dial:", err)
			return false // Took to long to dial, so the failure could have been due to the idle timeout.
		}

		ac = conn3.Call(ctx, "ping", nil)
		if err := ac.Await(ctx, nil); !errors.Is(err, jsonrpc2.ErrMethodNotFound) {
			if since := time.Since(idleStart); since < d {
				t.Fatalf("conn3 broken after %v: %v", since, err)
			}
			t.Log(`conn3.Call(ctx, "ping", nil):`, err)
			conn3.Close()
			return false
		}

		idleStart = time.Now()
		if err := conn3.Close(); err != nil {
			t.Fatalf("conn3.Close failed with error: %v", err)
		}

		serverError := server.Wait()

		if !errors.Is(serverError, jsonrpc2.ErrIdleTimeout) {
			t.Errorf("run() returned error %v, want %v", serverError, jsonrpc2.ErrIdleTimeout)
		}
		if since := time.Since(idleStart); since < d {
			t.Errorf("server shut down after %v idle; want at least %v", since, d)
		}
		return true
	}

	d := 1 * time.Millisecond
	for {
		t.Logf("testing with idle timeout %v", d)
		if !try(d) {
			d *= 2
			continue
		}
		break
	}
}

type msg struct {
	Msg string
}

type fakeHandler struct{}

func (fakeHandler) Handle(ctx context.Context, req *jsonrpc2.Request) (any, error) {
	switch req.Method {
	case "ping":
		return &msg{"pong"}, nil
	default:
		return nil, jsonrpc2.ErrNotHandled
	}
}

func TestServe(t *testing.T) {
	ctx := context.Background()

	tests := []struct {
		name    string
		factory func(context.Context, testing.TB) (jsonrpc2.Listener, error)
	}{
		{"tcp", func(ctx context.Context, t testing.TB) (jsonrpc2.Listener, error) {
			needsLocalhostNet(t)
			return jsonrpc2.NetListener(ctx, "tcp", "localhost:0", jsonrpc2.NetListenOptions{})
		}},
		{"pipe", func(ctx context.Context, t testing.TB) (jsonrpc2.Listener, error) {
			return jsonrpc2.NetPipeListener(ctx)
		}},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			fake, err := test.factory(ctx, t)
			if err != nil {
				t.Fatal(err)
			}
			conn, shutdown, err := newFake(t, ctx, fake)
			if err != nil {
				t.Fatal(err)
			}
			defer shutdown()
			var got msg
			if err := conn.Call(ctx, "ping", &msg{"ting"}).Await(ctx, &got); err != nil {
				t.Fatal(err)
			}
			if want := "pong"; got.Msg != want {
				t.Errorf("conn.Call(...): returned %q, want %q", got, want)
			}
		})
	}
}

func newFake(t *testing.T, ctx context.Context, l jsonrpc2.Listener) (*jsonrpc2.Connection, func(), error) {
	server := jsonrpc2.NewServer(ctx, l, jsonrpc2.ConnectionOptions{
		Handler: fakeHandler{},
	})

	client, err := jsonrpc2.Dial(ctx,
		l.Dialer(),
		jsonrpc2.ConnectionOptions{
			Handler: fakeHandler{},
		}, nil)
	if err != nil {
		return nil, nil, err
	}
	return client, func() {
		if err := l.Close(); err != nil {
			t.Fatal(err)
		}
		if err := client.Close(); err != nil {
			t.Fatal(err)
		}
		server.Wait()
	}, nil
}

// TestIdleListenerAcceptCloseRace checks for the Accept/Close race fixed in CL 388597.
//
// (A bug in the idleListener implementation caused a successful Accept to block
// on sending to a background goroutine that could have already exited.)
func TestIdleListenerAcceptCloseRace(t *testing.T) {
	ctx := context.Background()

	n := 10

	// Each iteration of the loop appears to take around a millisecond, so to
	// avoid spurious failures we'll set the watchdog for three orders of
	// magnitude longer. When the bug was present, this reproduced the deadlock
	// reliably on a Linux workstation when run with -count=100, which should be
	// frequent enough to show up on the Go build dashboard if it regresses.
	watchdog := time.Duration(n) * 1000 * time.Millisecond
	timer := time.AfterFunc(watchdog, func() {
		debug.SetTraceback("all")
		panic(fmt.Sprintf("%s deadlocked after %v", t.Name(), watchdog))
	})
	defer timer.Stop()

	for ; n > 0; n-- {
		listener, err := jsonrpc2.NetPipeListener(ctx)
		if err != nil {
			t.Fatal(err)
		}
		listener = jsonrpc2.NewIdleListener(24*time.Hour, listener)

		done := make(chan struct{})
		go func() {
			conn, err := jsonrpc2.Dial(ctx, listener.Dialer(), jsonrpc2.ConnectionOptions{}, nil)
			listener.Close()
			if err == nil {
				conn.Close()
			}
			close(done)
		}()

		// Accept may return a non-nil error if Close closes the underlying network
		// connection before the wrapped Accept call unblocks. However, it must not
		// deadlock!
		c, err := listener.Accept(ctx)
		if err == nil {
			c.Close()
		}
		<-done
	}
}

// TestCloseCallRace checks for a race resulting in a deadlock when a Call on
// one side of the connection races with a Close (or otherwise broken
// connection) initiated from the other side.
//
// (The Call method was waiting for a result from the Read goroutine to
// determine which error value to return, but the Read goroutine was waiting for
// in-flight calls to complete before reporting that result.)
func TestCloseCallRace(t *testing.T) {
	ctx := context.Background()
	n := 10

	watchdog := time.Duration(n) * 1000 * time.Millisecond
	timer := time.AfterFunc(watchdog, func() {
		debug.SetTraceback("all")
		panic(fmt.Sprintf("%s deadlocked after %v", t.Name(), watchdog))
	})
	defer timer.Stop()

	for ; n > 0; n-- {
		listener, err := jsonrpc2.NetPipeListener(ctx)
		if err != nil {
			t.Fatal(err)
		}

		pokec := make(chan *jsonrpc2.AsyncCall, 1)

		s := jsonrpc2.NewServer(ctx, listener, jsonrpc2.BinderFunc(func(_ context.Context, srvConn *jsonrpc2.Connection) jsonrpc2.ConnectionOptions {
			h := jsonrpc2.HandlerFunc(func(ctx context.Context, _ *jsonrpc2.Request) (any, error) {
				// Start a concurrent call from the server to the client.
				// The point of this test is to ensure this doesn't deadlock
				// if the client shuts down the connection concurrently.
				//
				// The racing Call may or may not receive a response: it should get a
				// response if it is sent before the client closes the connection, and
				// it should fail with some kind of "connection closed" error otherwise.
				go func() {
					pokec <- srvConn.Call(ctx, "poke", nil)
				}()

				return &msg{"pong"}, nil
			})
			return jsonrpc2.ConnectionOptions{Handler: h}
		}))

		dialConn, err := jsonrpc2.Dial(ctx, listener.Dialer(), jsonrpc2.ConnectionOptions{}, nil)
		if err != nil {
			listener.Close()
			s.Wait()
			t.Fatal(err)
		}

		// Calling any method on the server should provoke it to asynchronously call
		// us back. While it is starting that call, we will close the connection.
		if err := dialConn.Call(ctx, "ping", nil).Await(ctx, nil); err != nil {
			t.Error(err)
		}
		if err := dialConn.Close(); err != nil {
			t.Error(err)
		}

		// Ensure that the Call on the server side did not block forever when the
		// connection closed.
		pokeCall := <-pokec
		if err := pokeCall.Await(ctx, nil); err == nil {
			t.Errorf("unexpected nil error from server-initited call")
		} else if errors.Is(err, jsonrpc2.ErrMethodNotFound) {
			// The call completed before the Close reached the handler.
		} else {
			// The error was something else.
			t.Logf("server-initiated call completed with expected error: %v", err)
		}

		listener.Close()
		s.Wait()
	}
}


================================================
FILE: internal/jsonrpc2_v2/wire.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2

import (
	"encoding/json"
)

// This file contains the go forms of the wire specification.
// see http://www.jsonrpc.org/specification for details

var (
	// ErrParse is used when invalid JSON was received by the server.
	ErrParse = NewError(-32700, "JSON RPC parse error")
	// ErrInvalidRequest is used when the JSON sent is not a valid Request object.
	ErrInvalidRequest = NewError(-32600, "JSON RPC invalid request")
	// ErrMethodNotFound should be returned by the handler when the method does
	// not exist / is not available.
	ErrMethodNotFound = NewError(-32601, "JSON RPC method not found")
	// ErrInvalidParams should be returned by the handler when method
	// parameter(s) were invalid.
	ErrInvalidParams = NewError(-32602, "JSON RPC invalid params")
	// ErrInternal indicates a failure to process a call correctly
	ErrInternal = NewError(-32603, "JSON RPC internal error")

	// The following errors are not part of the json specification, but
	// compliant extensions specific to this implementation.

	// ErrServerOverloaded is returned when a message was refused due to a
	// server being temporarily unable to accept any new messages.
	ErrServerOverloaded = NewError(-32000, "JSON RPC overloaded")
	// ErrUnknown should be used for all non coded errors.
	ErrUnknown = NewError(-32001, "JSON RPC unknown error")
	// ErrServerClosing is returned for calls that arrive while the server is closing.
	ErrServerClosing = NewError(-32002, "JSON RPC server is closing")
	// ErrClientClosing is a dummy error returned for calls initiated while the client is closing.
	ErrClientClosing = NewError(-32003, "JSON RPC client is closing")
)

const wireVersion = "2.0"

// wireCombined has all the fields of both Request and Response.
// We can decode this and then work out which it is.
type wireCombined struct {
	VersionTag string          `json:"jsonrpc"`
	ID         any             `json:"id,omitempty"`
	Method     string          `json:"method,omitempty"`
	Params     json.RawMessage `json:"params,omitempty"`
	Result     json.RawMessage `json:"result,omitempty"`
	Error      *WireError      `json:"error,omitempty"`
}

// WireError represents a structured error in a Response.
type WireError struct {
	// Code is an error code indicating the type of failure.
	Code int64 `json:"code"`
	// Message is a short description of the error.
	Message string `json:"message"`
	// Data is optional structured data containing additional information about the error.
	Data json.RawMessage `json:"data,omitempty"`
}

// NewError returns an error that will encode on the wire correctly.
// The standard codes are made available from this package, this function should
// only be used to build errors for application specific codes as allowed by the
// specification.
func NewError(code int64, message string) error {
	return &WireError{
		Code:    code,
		Message: message,
	}
}

func (err *WireError) Error() string {
	return err.Message
}

func (err *WireError) Is(other error) bool {
	w, ok := other.(*WireError)
	if !ok {
		return false
	}
	return err.Code == w.Code
}


================================================
FILE: internal/jsonrpc2_v2/wire_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonrpc2_test

import (
	"bytes"
	"encoding/json"
	"reflect"
	"testing"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

func TestWireMessage(t *testing.T) {
	for _, test := range []struct {
		name    string
		msg     jsonrpc2.Message
		encoded []byte
	}{{
		name:    "notification",
		msg:     newNotification("alive", nil),
		encoded: []byte(`{"jsonrpc":"2.0","method":"alive"}`),
	}, {
		name:    "call",
		msg:     newCall("msg1", "ping", nil),
		encoded: []byte(`{"jsonrpc":"2.0","id":"msg1","method":"ping"}`),
	}, {
		name:    "response",
		msg:     newResponse("msg2", "pong", nil),
		encoded: []byte(`{"jsonrpc":"2.0","id":"msg2","result":"pong"}`),
	}, {
		name:    "numerical id",
		msg:     newCall(1, "poke", nil),
		encoded: []byte(`{"jsonrpc":"2.0","id":1,"method":"poke"}`),
	}, {
		// originally reported in #39719, this checks that result is not present if
		// it is an error response
		name: "computing fix edits",
		msg:  newResponse(3, nil, jsonrpc2.NewError(0, "computing fix edits")),
		encoded: []byte(`{
		"jsonrpc":"2.0",
		"id":3,
		"error":{
			"code":0,
			"message":"computing fix edits"
		}
	}`),
	}} {
		b, err := jsonrpc2.EncodeMessage(test.msg)
		if err != nil {
			t.Fatal(err)
		}
		checkJSON(t, b, test.encoded)
		msg, err := jsonrpc2.DecodeMessage(test.encoded)
		if err != nil {
			t.Fatal(err)
		}
		if !reflect.DeepEqual(msg, test.msg) {
			t.Errorf("decoded message does not match\nGot:\n%+#v\nWant:\n%+#v", msg, test.msg)
		}
	}
}

func newNotification(method string, params any) jsonrpc2.Message {
	msg, err := jsonrpc2.NewNotification(method, params)
	if err != nil {
		panic(err)
	}
	return msg
}

func newID(id any) jsonrpc2.ID {
	switch v := id.(type) {
	case nil:
		return jsonrpc2.ID{}
	case string:
		return jsonrpc2.StringID(v)
	case int:
		return jsonrpc2.Int64ID(int64(v))
	case int64:
		return jsonrpc2.Int64ID(v)
	default:
		panic("invalid ID type")
	}
}

func newCall(id any, method string, params any) jsonrpc2.Message {
	msg, err := jsonrpc2.NewCall(newID(id), method, params)
	if err != nil {
		panic(err)
	}
	return msg
}

func newResponse(id any, result any, rerr error) jsonrpc2.Message {
	msg, err := jsonrpc2.NewResponse(newID(id), result, rerr)
	if err != nil {
		panic(err)
	}
	return msg
}

func checkJSON(t *testing.T, got, want []byte) {
	// compare the compact form, to allow for formatting differences
	g := &bytes.Buffer{}
	if err := json.Compact(g, []byte(got)); err != nil {
		t.Fatal(err)
	}
	w := &bytes.Buffer{}
	if err := json.Compact(w, []byte(want)); err != nil {
		t.Fatal(err)
	}
	if g.String() != w.String() {
		t.Errorf("encoded message does not match\nGot:\n%s\nWant:\n%s", g, w)
	}
}


================================================
FILE: internal/mcp/CONTRIBUTING.md
================================================
# Contributing to the Go MCP SDK

Thank you for your interest in contributing! The Go SDK needs active
contributions to keep up with changes in the MCP spec, fix bugs, and accommodate
new and emerging use-cases. We welcome all forms of contribution, from filing
and reviewing issues, to contributing fixes, to proposing and implementing new
features.

As described in the [design document](./design/design.md), it is important for
the MCP SDK to remain idiomatic, future-proof, and extensible. The process
described here is intended to ensure that the SDK evolves safely and
transparently, while adhering to these goals.

## Development setup

This module can be built and tested using the standard Go toolchain. Run `go
test ./...` to run all its tests.

To test changes to this module against another module that uses the SDK, we
recommend using a [`go.work` file](https://go.dev/doc/tutorial/workspaces) to
define a multi-module workspace. For example, if your directory contains a
`project` directory containing your project, and a `go-sdk` directory
containing the SDK, run:

```sh
go work init ./project ./go-sdk
```

## Filing issues

This project uses the [GitHub issue
tracker](https://github.com/modelcontextprotocol/go-sdk/issues) for issues. The
process for filing bugs and proposals is described below.

TODO(rfindley): describe a process for asking general questions in the public
MCP discord server.

### Bugs

Please [report
bugs](https://github.com/modelcontextprotocol/go-sdk/issues/new). If the SDK is
not working as you expected, it is likely due to a bug or inadequate
documentation, and reporting an issue will help us address this shortcoming.

When reporting a bug, make sure to answer these five questions:

1. What did you do?
2. What did you see?
3. What did you expect to see?
4. What version of the Go MCP SDK are you using?
5. What version of Go are you using (`go version`)?

### Proposals

A proposal is an issue that proposes a new API for the SDK, or a change to the
signature or behavior of an existing API. Proposals are be labeled with the
'Proposal' label, and require an explicit approval from a maintainer before
being accepted (indicated by the 'Proposal-Accepted' label). Proposals must
remain open for at least a week to allow discussion before being accepted or
declined by a maintainer.

Proposals that are straightforward and uncontroversial may be approved based on
GitHub discussion. However, proposals that are deemed to be sufficiently
unclear or complicated may be deferred to a regular steering meeting (see
'Governance' below).

This process is similar to the [Go proposal
process](https://github.com/golang/proposal), but is necessarily lighter weight
to accommodate the greater rate of change expected for the SDK.

## Contributing code

The project uses GitHub pull requests (PRs) to review changes.

Any significant change should be associated with a GitHub issue. Issues that
are deemed to be good opportunities for contribution are be labeled ['Help
Wanted'](https://github.com/modelcontextprotocol/go-sdk/issues?q=is%3Aissue%20state%3Aopen%20label%3A%22help%20wanted%22).
If you want to work on such an issue, please first comment on the issue to say
that you're interested in contributing. For issues _not_ labeled 'Help Wanted',
it is recommended that you ask (and wait for confirmation) on the issue before
contributing, to avoid duplication of effort or wasted work. For nontrivial
changes that _don't_ relate to an existing issue, please file an issue first.

Changes should be high quality and well tested, and should generally follow the
[Google Go style guide](https://google.github.io/styleguide/go/). Commit
messages should follow the [format used by the Go
project](https://go.dev/wiki/CommitMessage).

Unless otherwise noted, the Go source files are distributed under the MIT-style
license found in the LICENSE file. All Go files in the SDK should have a
copyright header following the format below:

```go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
```

## Code of conduct

This project follows the [Go Community Code of Conduct](https://go.dev/conduct).
If you encounter a conduct-related issue, please mail conduct@golang.org.

## Governance

Initially, the Go SDK repository will be administered by the Go team and
Anthropic, and they will be the Approvers (the set of people able to merge PRs
to the SDK). The policies here are also intended to satisfy necessary
constraints of the Go team's participation in the project. This may change in
the future: see 'Ongoing Evaluation' below.

### Steering meetings

On a regular basis, the maintainers will host a virtual steering meeting to
discuss outstanding proposals and other changes to the SDK. These meetings and
their agendas will be announced in advance, and open to all to join. The
meetings will be recorded, and recordings and meeting notes will be made
available afterward. (TODO: decide on a mechanism for tracking these
meetings--likely a GitHub issue.)

This process is similar to the [Go Tools
call](https://go.dev/wiki/golang-tools), though it is expected that meetings
will at least initially occur on a more frequent basis.

### Discord

Discord (either the public or private Anthropic discord servers) should only be
used for logistical coordination or answering questions. For transparency and
durability, design discussion and decisions should occur in GitHub issues or
public steering meetings.

### Antitrust considerations

It is important that the SDK avoids bias toward specific integration paths or
providers. The antitrust policy below details precise terms that should be
avoided to ensure that the evolution and governance of the SDK remain
procompetitive.

A note to readers: this policy was drafted in consultation with counsel, and so
uses terms like 'Steering Committee', which may be confusing in the context of
other 'steering committees' for model context protocol. In the context here,
'Steering Committee' means the set of Approvers, who are able to approve pull
requests and/or make administrative changes to the project.

### Antitrust policy

Note: all changes to the policy in this section must be approved by legal
counsel.

The Go+Anthropic MCP SDK Steering Committee (the “Committee”) is established to
guide and review technical contributions to an open-source Go software
development kit (“SDK”) for the Model Context Protocol (“MCP”). The Committee
and its members are committed to operating for procompetitive purposes that
accelerate AI development and benefit businesses and consumers. This
collaboration is focused on technical and infrastructure objectives – namely,
developing and maintaining a neutral, open-source, and MIT-licensed tool.
Google and Anthropic, as well as other stakeholders, participate with the
understanding that the Committee’s sole purpose is to improve interoperability
and innovation in the MCP ecosystem.

Antitrust law recognizes that when competitors collaborate for valid reasons
(e.g., joint R&D or standard-setting), such collaborations can be
procompetitive. This Antitrust Compliance Policy (the “Policy”) therefore
outlines guidelines and safeguards to ensure the collaboration remains focused
on its technical mission.

The Policy applies to all Committee activities and communications, including
official meetings, subcommittee discussions, emails, shared documents, and any
other interactions under the Committee’s auspices (e.g., group chats, version
control systems). It applies to all participants from Google, Anthropic, and
any other member organizations or independent contributors involved. Each
participating entity should ensure its representatives understand and uphold
these rules. By participating, members agree to follow the Policy in both
letter and spirit.

#### Governance Procedures and Principles

- **Participant Guidelines.** Participants should generally be limited to
  individuals in technical roles who are directly involved in the MCP SDK
  project. These participants should not be key decision-makers in their
  company’s AI commercial strategy, sales, marketing, pricing, or other
  competitively or strategically sensitive business planning.
- **Agenda Preparation.** A written agenda should be circulated before each
  Committee meeting. Agenda items should focus on the SDK’s technical
  development, maintenance, or documentation. Where appropriate, counsel should
  review the agenda prior to circulation to ensure compliance with the Policy.
- **Policy Reminder at Start.** Meetings should begin with a brief antitrust
  compliance reminder with reference to the Policy.
- **Minutes.** Meetings will be minuted by a designated participant, and
  neutrally record attendees, roles, topics discussed, action items, and
  outcomes. Draft minutes will be circulated to all participants.
- **Documentation and Transparency.** Steering Committee outputs are intended
  for public release. Significant design decisions and discussion outcomes
  should be documented publicly. If a topic cannot be safely disclosed
  publicly, it likely does not belong in this forum.
- **Independence of Decision-Making.** All participants and their companies
  retain complete independence in their own business decisions and competitive
  strategies outside of the MCP SDK project. Nothing in this collaboration
  restricts or influences how each company operates its commercial business.

### Information Exchange Guidelines

**Appropriate Topics.** Committee members are anticipated to remain within the
project’s technical scope. In general, discussions should focus on improving
the Go SDK for MCP in a transparent, collaborative, and non-exclusive manner.
The following topics are appropriate and expected:

- **Software Design and Architecture:** Implementation of MCP features in Go,
  API design, code structure, testing frameworks, performance considerations,
  compatibility issues, and security concerns.
- **Technical Contributions and Bug Fixes:** Review of code contributions,
  debugging problems, and handling feature requests.
- **Documentation and Open-Source Logistics:** Discussions of project
  documentation, changelogs, versioning strategy, and managing contributions.
- **Standards and Interoperability:** Ensuring SDK compliance with MCP or other
  open technical standards. Any standardization effort should be open,
  voluntary, and tailored to promote interoperability.
- **Public Information:** Any public information relevant to the Committee’s
  technical work (e.g., published research, open-source code from outside
  projects, publicly documented API specs).

**Inappropriate Topics.** To ensure compliance with antitrust law and maintain
the open character of the collaboration, the following subjects should not be
discussed in Committee meetings, side conversations, or related communications:

- **Pricing and Commercial Terms:** Do not discuss prices, pricing strategy,
  discounting, or future pricing plans for Claude, Gemini, or any other AI
  product or service provided by Committee members.
- **Sales or Output:** Avoid sharing sales volumes, revenue, customer counts,
  market shares, production plans, or any business performance metrics.
- **Product Roadmaps (beyond SDK):** Do not disclose internal plans for AI
  model development, feature rollouts, or future commercialization strategies.
- **Customers or Markets:** No discussions of which customers, industries, or
  geographies the parties will pursue or avoid.
- **Customer or Supplier Details:** Do not share specifics of contracts,
  negotiations, or relationships with commercial partners.
- **Non-SDK Proprietary Tech:** Keep discussions focused on the open SDK.
  Sharing of information should be limited to what is needed to achieve the
  Committee’s goals. Each party’s internal model architectures, fine-tuning
  approaches, or training methods unrelated to the project should not be
  disclosed.
- **HR or Labor Matters:** No discussions about wages, hiring plans, or
  policies toward employees.

#### Enforcement and Support

- **Shared Responsibility.** All Committee participants share responsibility
  for upholding the Policy. While legal counsel can provide support, day-to-day
  compliance is a function of culture and practice.
- **Designated Legal Contacts.** Each participating entity should designate a
  legal point of contact responsible for reviewing meeting materials (e.g.,
  agendas, minutes) and fielding questions about compliance. These contacts
  should be included in the Committee distribution list for all official
  materials and should be consulted in advance of any meetings where sensitive
  topics may arise.
- **Final Note.** The Policy is not meant to chill legitimate technical
  collaboration. It is meant to ensure that the Committee can focus on its
  mission without creating unnecessary legal risk or attracting regulator
  scrutiny. Participants who follow the Policy and avoid Inappropriate Topics
  will remain squarely within the procompetitive zone.

### Ongoing evaluation

On an ongoing basis, the administrators of the SDK will evaluate whether it is
keeping pace with changes to the MCP spec and meeting its goals of openness and
transparency. If it is not meeting these goals, either because it exceeds the
bandwidth of its current Approvers, or because the processes here are
inadequate, these processes will be re-evaluated by the Approvers. At this
time, the Approvers set may be expanded to include additional community
members, based on their history of strong contribution.


================================================
FILE: internal/mcp/README.md
================================================
<!-- Autogenerated by weave; DO NOT EDIT -->
# MCP Go SDK

<!-- TODO: update pkgsite links here to point to the modelcontextprotocol
module, once it exists. -->

[![PkgGoDev](https://pkg.go.dev/badge/golang.org/x/tools)](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk)

This repository contains an implementation of the official Go software
development kit (SDK) for the Model Context Protocol (MCP).

**WARNING**: The SDK is currently unstable and subject to breaking changes.
Please test it out and file bug reports or API proposals. The [TODO](#todo)
section below outlines outstanding release blockers. We aim to release a stable
version of the SDK in mid July, 2025.

	1. [Package documentation](#package-documentation)
	1. [Example](#example)
	1. [TODO](#todo)
	1. [Design](#design)
	1. [Acknowledgements](#acknowledgements)
	1. [License](#license)

## Package documentation

The SDK consists of two importable packages:

- The
  [`github.com/modelcontextprotocol/go-sdk/mcp`](https://pkg.go.dev/golang.org/x/tools/internal/mcp)
  package defines the primary APIs for constructing and using MCP clients and
  servers.
- The
  [`github.com/modelcontextprotocol/go-sdk/jsonschema`](https://pkg.go.dev/golang.org/x/tools/internal/mcp/jsonschema)
  package provides an implementation of [JSON
  Schema](https://json-schema.org/), used for MCP tool input and output schema.

## Example

In this example, an MCP client communicates with an MCP server running in a
sidecar process:

```go
package main

import (
	"context"
	"log"
	"os/exec"

	"golang.org/x/tools/internal/mcp"
)

func main() {
	ctx := context.Background()

	// Create a new client, with no features.
	client := mcp.NewClient("mcp-client", "v1.0.0", nil)

	// Connect to a server over stdin/stdout
	transport := mcp.NewCommandTransport(exec.Command("myserver"))
	session, err := client.Connect(ctx, transport)
	if err != nil {
		log.Fatal(err)
	}
	defer session.Close()

	// Call a tool on the server.
	params := &mcp.CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "you"},
	}
	res, err := session.CallTool(ctx, params)
	if err != nil {
		log.Fatalf("CallTool failed: %v", err)
	}
	if res.IsError {
		log.Fatal("tool failed")
	}
	for _, c := range res.Content {
		log.Print(c.Text)
	}
}
```

Here's an example of the corresponding server component, which communicates
with its client over stdin/stdout:

```go
package main

import (
	"context"
	"log"

	"golang.org/x/tools/internal/mcp"
)

type HiParams struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, cc *mcp.ServerSession, params *mcp.CallToolParamsFor[HiParams]) (*mcp.CallToolResultFor[any], error) {
	return &mcp.CallToolResultFor[any]{
		Content: []*mcp.Content{mcp.NewTextContent("Hi " + params.Name)},
	}, nil
}

func main() {
	// Create a server with a single tool.
	server := mcp.NewServer("greeter", "v1.0.0", nil)
	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))
	// Run the server over stdin/stdout, until the client disconnects
	if err := server.Run(context.Background(), mcp.NewStdioTransport()); err != nil {
		log.Fatal(err)
	}
}
```

The `examples/` directory contains more example clients and servers.

## TODO

The following TODOs block the release of this SDK:

- Better support for resumability in the Streamable HTTP transport: a
  server-side event store and client-side retry configuration.
- OAuth support (or examples of implementing OAuth using middleware).
- Support for the changes in the
  [2025-06-18](https://modelcontextprotocol.io/specification/2025-06-18/changelog)
  version of the MCP spec.
- More examples and documentation.

## Design

The design doc for this SDK is at [design.md](./design/design.md), which was
initially reviewed at
[modelcontextprotocol/discussions/364](https://github.com/orgs/modelcontextprotocol/discussions/364).

Further design discussion should occur in GitHub issues. See CONTRIBUTING.md
for details.

## Acknowledgements

Several existing Go MCP SDKs inspired the development and design of this
official SDK, notably [mcp-go](https://github.com/mark3labs/mcp-go), authored
by Ed Zynda. We are grateful to Ed as well as the other contributors to mcp-go,
and to authors and contributors of other SDKs such as
[mcp-golang](https://github.com/metoro-io/mcp-golang) and
[go-mcp](https://github.com/ThinkInAIXYZ/go-mcp). Thanks to their work, there
is a thriving ecosystem of Go MCP clients and servers.

## License

This project is licensed under the MIT License - see the [LICENSE](./LICENSE)
file for details.


================================================
FILE: internal/mcp/client.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"iter"
	"slices"
	"sync"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

// A Client is an MCP client, which may be connected to an MCP server
// using the [Client.Connect] method.
type Client struct {
	name                    string
	version                 string
	opts                    ClientOptions
	mu                      sync.Mutex
	roots                   *featureSet[*Root]
	sessions                []*ClientSession
	sendingMethodHandler_   MethodHandler[*ClientSession]
	receivingMethodHandler_ MethodHandler[*ClientSession]
}

// NewClient creates a new Client.
//
// Use [Client.Connect] to connect it to an MCP server.
//
// If non-nil, the provided options configure the Client.
func NewClient(name, version string, opts *ClientOptions) *Client {
	c := &Client{
		name:                    name,
		version:                 version,
		roots:                   newFeatureSet(func(r *Root) string { return r.URI }),
		sendingMethodHandler_:   defaultSendingMethodHandler[*ClientSession],
		receivingMethodHandler_: defaultReceivingMethodHandler[*ClientSession],
	}
	if opts != nil {
		c.opts = *opts
	}
	return c
}

// ClientOptions configures the behavior of the client.
type ClientOptions struct {
	// Handler for sampling.
	// Called when a server calls CreateMessage.
	CreateMessageHandler func(context.Context, *ClientSession, *CreateMessageParams) (*CreateMessageResult, error)
	// Handlers for notifications from the server.
	ToolListChangedHandler      func(context.Context, *ClientSession, *ToolListChangedParams)
	PromptListChangedHandler    func(context.Context, *ClientSession, *PromptListChangedParams)
	ResourceListChangedHandler  func(context.Context, *ClientSession, *ResourceListChangedParams)
	LoggingMessageHandler       func(context.Context, *ClientSession, *LoggingMessageParams)
	ProgressNotificationHandler func(context.Context, *ClientSession, *ProgressNotificationParams)
}

// bind implements the binder[*ClientSession] interface, so that Clients can
// be connected using [connect].
func (c *Client) bind(conn *jsonrpc2.Connection) *ClientSession {
	cs := &ClientSession{
		conn:   conn,
		client: c,
	}
	c.mu.Lock()
	defer c.mu.Unlock()
	c.sessions = append(c.sessions, cs)
	return cs
}

// disconnect implements the binder[*Client] interface, so that
// Clients can be connected using [connect].
func (c *Client) disconnect(cs *ClientSession) {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.sessions = slices.DeleteFunc(c.sessions, func(cs2 *ClientSession) bool {
		return cs2 == cs
	})
}

// Connect begins an MCP session by connecting to a server over the given
// transport, and initializing the session.
//
// Typically, it is the responsibility of the client to close the connection
// when it is no longer needed. However, if the connection is closed by the
// server, calls or notifications will return an error wrapping
// [ErrConnectionClosed].
func (c *Client) Connect(ctx context.Context, t Transport) (cs *ClientSession, err error) {
	cs, err = connect(ctx, t, c)
	if err != nil {
		return nil, err
	}

	caps := &ClientCapabilities{}
	caps.Roots.ListChanged = true
	if c.opts.CreateMessageHandler != nil {
		caps.Sampling = &SamplingCapabilities{}
	}

	params := &InitializeParams{
		ClientInfo:      &implementation{Name: c.name, Version: c.version},
		Capabilities:    caps,
		ProtocolVersion: "2025-03-26",
	}
	// TODO(rfindley): handle protocol negotiation gracefully. If the server
	// responds with 2024-11-05, surface that failure to the caller of connect,
	// so that they can choose a different transport.
	res, err := handleSend[*InitializeResult](ctx, cs, methodInitialize, params)
	if err != nil {
		_ = cs.Close()
		return nil, err
	}
	cs.initializeResult = res
	if err := handleNotify(ctx, cs, notificationInitialized, &InitializedParams{}); err != nil {
		_ = cs.Close()
		return nil, err
	}
	return cs, nil
}

// A ClientSession is a logical connection with an MCP server. Its
// methods can be used to send requests or notifications to the server. Create
// a session by calling [Client.Connect].
//
// Call [ClientSession.Close] to close the connection, or await client
// termination with [ServerSession.Wait].
type ClientSession struct {
	conn             *jsonrpc2.Connection
	client           *Client
	initializeResult *InitializeResult
}

// Close performs a graceful close of the connection, preventing new requests
// from being handled, and waiting for ongoing requests to return. Close then
// terminates the connection.
func (cs *ClientSession) Close() error {
	return cs.conn.Close()
}

// Wait waits for the connection to be closed by the server.
// Generally, clients should be responsible for closing the connection.
func (cs *ClientSession) Wait() error {
	return cs.conn.Wait()
}

// AddRoots adds the given roots to the client,
// replacing any with the same URIs,
// and notifies any connected servers.
func (c *Client) AddRoots(roots ...*Root) {
	// Only notify if something could change.
	if len(roots) == 0 {
		return
	}
	c.changeAndNotify(notificationRootsListChanged, &RootsListChangedParams{},
		func() bool { c.roots.add(roots...); return true })
}

// RemoveRoots removes the roots with the given URIs,
// and notifies any connected servers if the list has changed.
// It is not an error to remove a nonexistent root.
// TODO: notification
func (c *Client) RemoveRoots(uris ...string) {
	c.changeAndNotify(notificationRootsListChanged, &RootsListChangedParams{},
		func() bool { return c.roots.remove(uris...) })
}

// changeAndNotify is called when a feature is added or removed.
// It calls change, which should do the work and report whether a change actually occurred.
// If there was a change, it notifies a snapshot of the sessions.
func (c *Client) changeAndNotify(notification string, params Params, change func() bool) {
	var sessions []*ClientSession
	// Lock for the change, but not for the notification.
	c.mu.Lock()
	if change() {
		sessions = slices.Clone(c.sessions)
	}
	c.mu.Unlock()
	notifySessions(sessions, notification, params)
}

func (c *Client) listRoots(_ context.Context, _ *ClientSession, _ *ListRootsParams) (*ListRootsResult, error) {
	c.mu.Lock()
	defer c.mu.Unlock()
	roots := slices.Collect(c.roots.all())
	if roots == nil {
		roots = []*Root{} // avoid JSON null
	}
	return &ListRootsResult{
		Roots: roots,
	}, nil
}

func (c *Client) createMessage(ctx context.Context, cs *ClientSession, params *CreateMessageParams) (*CreateMessageResult, error) {
	if c.opts.CreateMessageHandler == nil {
		// TODO: wrap or annotate this error? Pick a standard code?
		return nil, &jsonrpc2.WireError{Code: CodeUnsupportedMethod, Message: "client does not support CreateMessage"}
	}
	return c.opts.CreateMessageHandler(ctx, cs, params)
}

// AddSendingMiddleware wraps the current sending method handler using the provided
// middleware. Middleware is applied from right to left, so that the first one is
// executed first.
//
// For example, AddSendingMiddleware(m1, m2, m3) augments the method handler as
// m1(m2(m3(handler))).
//
// Sending middleware is called when a request is sent. It is useful for tasks
// such as tracing, metrics, and adding progress tokens.
func (c *Client) AddSendingMiddleware(middleware ...Middleware[*ClientSession]) {
	c.mu.Lock()
	defer c.mu.Unlock()
	addMiddleware(&c.sendingMethodHandler_, middleware)
}

// AddReceivingMiddleware wraps the current receiving method handler using
// the provided middleware. Middleware is applied from right to left, so that the
// first one is executed first.
//
// For example, AddReceivingMiddleware(m1, m2, m3) augments the method handler as
// m1(m2(m3(handler))).
//
// Receiving middleware is called when a request is received. It is useful for tasks
// such as authentication, request logging and metrics.
func (c *Client) AddReceivingMiddleware(middleware ...Middleware[*ClientSession]) {
	c.mu.Lock()
	defer c.mu.Unlock()
	addMiddleware(&c.receivingMethodHandler_, middleware)
}

// clientMethodInfos maps from the RPC method name to serverMethodInfos.
var clientMethodInfos = map[string]methodInfo{
	methodPing:                      newMethodInfo(sessionMethod((*ClientSession).ping)),
	methodListRoots:                 newMethodInfo(clientMethod((*Client).listRoots)),
	methodCreateMessage:             newMethodInfo(clientMethod((*Client).createMessage)),
	notificationToolListChanged:     newMethodInfo(clientMethod((*Client).callToolChangedHandler)),
	notificationPromptListChanged:   newMethodInfo(clientMethod((*Client).callPromptChangedHandler)),
	notificationResourceListChanged: newMethodInfo(clientMethod((*Client).callResourceChangedHandler)),
	notificationLoggingMessage:      newMethodInfo(clientMethod((*Client).callLoggingHandler)),
	notificationProgress:            newMethodInfo(sessionMethod((*ClientSession).callProgressNotificationHandler)),
}

func (cs *ClientSession) sendingMethodInfos() map[string]methodInfo {
	return serverMethodInfos
}

func (cs *ClientSession) receivingMethodInfos() map[string]methodInfo {
	return clientMethodInfos
}

func (cs *ClientSession) handle(ctx context.Context, req *JSONRPCRequest) (any, error) {
	return handleReceive(ctx, cs, req)
}

func (cs *ClientSession) sendingMethodHandler() methodHandler {
	cs.client.mu.Lock()
	defer cs.client.mu.Unlock()
	return cs.client.sendingMethodHandler_
}

func (cs *ClientSession) receivingMethodHandler() methodHandler {
	cs.client.mu.Lock()
	defer cs.client.mu.Unlock()
	return cs.client.receivingMethodHandler_
}

// getConn implements [session.getConn].
func (cs *ClientSession) getConn() *jsonrpc2.Connection { return cs.conn }

func (*ClientSession) ping(context.Context, *PingParams) (*emptyResult, error) {
	return &emptyResult{}, nil
}

// Ping makes an MCP "ping" request to the server.
func (cs *ClientSession) Ping(ctx context.Context, params *PingParams) error {
	_, err := handleSend[*emptyResult](ctx, cs, methodPing, orZero[Params](params))
	return err
}

// ListPrompts lists prompts that are currently available on the server.
func (cs *ClientSession) ListPrompts(ctx context.Context, params *ListPromptsParams) (*ListPromptsResult, error) {
	return handleSend[*ListPromptsResult](ctx, cs, methodListPrompts, orZero[Params](params))
}

// GetPrompt gets a prompt from the server.
func (cs *ClientSession) GetPrompt(ctx context.Context, params *GetPromptParams) (*GetPromptResult, error) {
	return handleSend[*GetPromptResult](ctx, cs, methodGetPrompt, orZero[Params](params))
}

// ListTools lists tools that are currently available on the server.
func (cs *ClientSession) ListTools(ctx context.Context, params *ListToolsParams) (*ListToolsResult, error) {
	return handleSend[*ListToolsResult](ctx, cs, methodListTools, orZero[Params](params))
}

// CallTool calls the tool with the given name and arguments.
// The arguments can be any value that marshals into a JSON object.
func (cs *ClientSession) CallTool(ctx context.Context, params *CallToolParams) (*CallToolResult, error) {
	if params == nil {
		params = new(CallToolParams)
	}
	if params.Arguments == nil {
		// Avoid sending nil over the wire.
		params.Arguments = map[string]any{}
	}
	return handleSend[*CallToolResult](ctx, cs, methodCallTool, params)
}

func (cs *ClientSession) SetLevel(ctx context.Context, params *SetLevelParams) error {
	_, err := handleSend[*emptyResult](ctx, cs, methodSetLevel, orZero[Params](params))
	return err
}

// ListResources lists the resources that are currently available on the server.
func (cs *ClientSession) ListResources(ctx context.Context, params *ListResourcesParams) (*ListResourcesResult, error) {
	return handleSend[*ListResourcesResult](ctx, cs, methodListResources, orZero[Params](params))
}

// ListResourceTemplates lists the resource templates that are currently available on the server.
func (cs *ClientSession) ListResourceTemplates(ctx context.Context, params *ListResourceTemplatesParams) (*ListResourceTemplatesResult, error) {
	return handleSend[*ListResourceTemplatesResult](ctx, cs, methodListResourceTemplates, orZero[Params](params))
}

// ReadResource ask the server to read a resource and return its contents.
func (cs *ClientSession) ReadResource(ctx context.Context, params *ReadResourceParams) (*ReadResourceResult, error) {
	return handleSend[*ReadResourceResult](ctx, cs, methodReadResource, orZero[Params](params))
}

func (c *Client) callToolChangedHandler(ctx context.Context, s *ClientSession, params *ToolListChangedParams) (Result, error) {
	return callNotificationHandler(ctx, c.opts.ToolListChangedHandler, s, params)
}

func (c *Client) callPromptChangedHandler(ctx context.Context, s *ClientSession, params *PromptListChangedParams) (Result, error) {
	return callNotificationHandler(ctx, c.opts.PromptListChangedHandler, s, params)
}

func (c *Client) callResourceChangedHandler(ctx context.Context, s *ClientSession, params *ResourceListChangedParams) (Result, error) {
	return callNotificationHandler(ctx, c.opts.ResourceListChangedHandler, s, params)
}

func (c *Client) callLoggingHandler(ctx context.Context, cs *ClientSession, params *LoggingMessageParams) (Result, error) {
	if h := c.opts.LoggingMessageHandler; h != nil {
		h(ctx, cs, params)
	}
	return nil, nil
}

func (cs *ClientSession) callProgressNotificationHandler(ctx context.Context, params *ProgressNotificationParams) (Result, error) {
	return callNotificationHandler(ctx, cs.client.opts.ProgressNotificationHandler, cs, params)
}

// NotifyProgress sends a progress notification from the client to the server
// associated with this session.
// This can be used if the client is performing a long-running task that was
// initiated by the server
func (cs *ClientSession) NotifyProgress(ctx context.Context, params *ProgressNotificationParams) error {
	return handleNotify(ctx, cs, notificationProgress, params)
}

// Tools provides an iterator for all tools available on the server,
// automatically fetching pages and managing cursors.
// The params argument can set the initial cursor.
// Iteration stops at the first encountered error, which will be yielded.
func (cs *ClientSession) Tools(ctx context.Context, params *ListToolsParams) iter.Seq2[*Tool, error] {
	if params == nil {
		params = &ListToolsParams{}
	}
	return paginate(ctx, params, cs.ListTools, func(res *ListToolsResult) []*Tool {
		return res.Tools
	})
}

// Resources provides an iterator for all resources available on the server,
// automatically fetching pages and managing cursors.
// The params argument can set the initial cursor.
// Iteration stops at the first encountered error, which will be yielded.
func (cs *ClientSession) Resources(ctx context.Context, params *ListResourcesParams) iter.Seq2[*Resource, error] {
	if params == nil {
		params = &ListResourcesParams{}
	}
	return paginate(ctx, params, cs.ListResources, func(res *ListResourcesResult) []*Resource {
		return res.Resources
	})
}

// ResourceTemplates provides an iterator for all resource templates available on the server,
// automatically fetching pages and managing cursors.
// The `params` argument can set the initial cursor.
// Iteration stops at the first encountered error, which will be yielded.
func (cs *ClientSession) ResourceTemplates(ctx context.Context, params *ListResourceTemplatesParams) iter.Seq2[*ResourceTemplate, error] {
	if params == nil {
		params = &ListResourceTemplatesParams{}
	}
	return paginate(ctx, params, cs.ListResourceTemplates, func(res *ListResourceTemplatesResult) []*ResourceTemplate {
		return res.ResourceTemplates
	})
}

// Prompts provides an iterator for all prompts available on the server,
// automatically fetching pages and managing cursors.
// The params argument can set the initial cursor.
// Iteration stops at the first encountered error, which will be yielded.
func (cs *ClientSession) Prompts(ctx context.Context, params *ListPromptsParams) iter.Seq2[*Prompt, error] {
	if params == nil {
		params = &ListPromptsParams{}
	}
	return paginate(ctx, params, cs.ListPrompts, func(res *ListPromptsResult) []*Prompt {
		return res.Prompts
	})
}

// paginate is a generic helper function to provide a paginated iterator.
func paginate[P listParams, R listResult[T], T any](ctx context.Context, params P, listFunc func(context.Context, P) (R, error), items func(R) []*T) iter.Seq2[*T, error] {
	return func(yield func(*T, error) bool) {
		for {
			res, err := listFunc(ctx, params)
			if err != nil {
				yield(nil, err)
				return
			}
			for _, r := range items(res) {
				if !yield(r, nil) {
					return
				}
			}
			nextCursorVal := res.nextCursorPtr()
			if nextCursorVal == nil || *nextCursorVal == "" {
				return
			}
			*params.cursorPtr() = *nextCursorVal
		}
	}
}


================================================
FILE: internal/mcp/client_list_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"iter"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/internal/mcp"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

func TestList(t *testing.T) {
	ctx := context.Background()
	clientSession, serverSession, server := createSessions(ctx)
	defer clientSession.Close()
	defer serverSession.Close()

	t.Run("tools", func(t *testing.T) {
		toolA := mcp.NewServerTool("apple", "apple tool", SayHi)
		toolB := mcp.NewServerTool("banana", "banana tool", SayHi)
		toolC := mcp.NewServerTool("cherry", "cherry tool", SayHi)
		tools := []*mcp.ServerTool{toolA, toolB, toolC}
		wantTools := []*mcp.Tool{toolA.Tool, toolB.Tool, toolC.Tool}
		server.AddTools(tools...)
		t.Run("list", func(t *testing.T) {
			res, err := clientSession.ListTools(ctx, nil)
			if err != nil {
				t.Fatal("ListTools() failed:", err)
			}
			if diff := cmp.Diff(wantTools, res.Tools, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("ListTools() mismatch (-want +got):\n%s", diff)
			}
		})
		t.Run("iterator", func(t *testing.T) {
			testIterator(t, clientSession.Tools(ctx, nil), wantTools)
		})
	})

	t.Run("resources", func(t *testing.T) {
		resourceA := &mcp.ServerResource{Resource: &mcp.Resource{URI: "http://apple"}}
		resourceB := &mcp.ServerResource{Resource: &mcp.Resource{URI: "http://banana"}}
		resourceC := &mcp.ServerResource{Resource: &mcp.Resource{URI: "http://cherry"}}
		wantResources := []*mcp.Resource{resourceA.Resource, resourceB.Resource, resourceC.Resource}
		resources := []*mcp.ServerResource{resourceA, resourceB, resourceC}
		server.AddResources(resources...)
		t.Run("list", func(t *testing.T) {
			res, err := clientSession.ListResources(ctx, nil)
			if err != nil {
				t.Fatal("ListResources() failed:", err)
			}
			if diff := cmp.Diff(wantResources, res.Resources, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("ListResources() mismatch (-want +got):\n%s", diff)
			}
		})
		t.Run("iterator", func(t *testing.T) {
			testIterator(t, clientSession.Resources(ctx, nil), wantResources)
		})
	})

	t.Run("templates", func(t *testing.T) {
		resourceTmplA := &mcp.ServerResourceTemplate{ResourceTemplate: &mcp.ResourceTemplate{URITemplate: "http://apple/{x}"}}
		resourceTmplB := &mcp.ServerResourceTemplate{ResourceTemplate: &mcp.ResourceTemplate{URITemplate: "http://banana/{x}"}}
		resourceTmplC := &mcp.ServerResourceTemplate{ResourceTemplate: &mcp.ResourceTemplate{URITemplate: "http://cherry/{x}"}}
		wantResourceTemplates := []*mcp.ResourceTemplate{
			resourceTmplA.ResourceTemplate, resourceTmplB.ResourceTemplate,
			resourceTmplC.ResourceTemplate,
		}
		resourceTemplates := []*mcp.ServerResourceTemplate{resourceTmplA, resourceTmplB, resourceTmplC}
		server.AddResourceTemplates(resourceTemplates...)
		t.Run("list", func(t *testing.T) {
			res, err := clientSession.ListResourceTemplates(ctx, nil)
			if err != nil {
				t.Fatal("ListResourceTemplates() failed:", err)
			}
			if diff := cmp.Diff(wantResourceTemplates, res.ResourceTemplates, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("ListResourceTemplates() mismatch (-want +got):\n%s", diff)
			}
		})
		t.Run("ResourceTemplatesIterator", func(t *testing.T) {
			testIterator(t, clientSession.ResourceTemplates(ctx, nil), wantResourceTemplates)
		})
	})

	t.Run("prompts", func(t *testing.T) {
		promptA := newServerPrompt("apple", "apple prompt")
		promptB := newServerPrompt("banana", "banana prompt")
		promptC := newServerPrompt("cherry", "cherry prompt")
		wantPrompts := []*mcp.Prompt{promptA.Prompt, promptB.Prompt, promptC.Prompt}
		prompts := []*mcp.ServerPrompt{promptA, promptB, promptC}
		server.AddPrompts(prompts...)
		t.Run("list", func(t *testing.T) {
			res, err := clientSession.ListPrompts(ctx, nil)
			if err != nil {
				t.Fatal("ListPrompts() failed:", err)
			}
			if diff := cmp.Diff(wantPrompts, res.Prompts, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("ListPrompts() mismatch (-want +got):\n%s", diff)
			}
		})
		t.Run("iterator", func(t *testing.T) {
			testIterator(t, clientSession.Prompts(ctx, nil), wantPrompts)
		})
	})
}

func testIterator[T any](t *testing.T, seq iter.Seq2[*T, error], want []*T) {
	t.Helper()
	var got []*T
	for x, err := range seq {
		if err != nil {
			t.Fatalf("iteration failed: %v", err)
		}
		got = append(got, x)
	}
	if diff := cmp.Diff(want, got, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
		t.Fatalf("mismatch (-want +got):\n%s", diff)
	}
}

// testPromptHandler is used for type inference newServerPrompt.
func testPromptHandler(context.Context, *mcp.ServerSession, *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
	panic("not implemented")
}

func newServerPrompt(name, desc string) *mcp.ServerPrompt {
	return &mcp.ServerPrompt{
		Prompt:  &mcp.Prompt{Name: name, Description: desc},
		Handler: testPromptHandler,
	}
}


================================================
FILE: internal/mcp/client_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

type Item struct {
	Name  string
	Value string
}

type ListTestParams struct {
	Cursor string
}

func (p *ListTestParams) cursorPtr() *string {
	return &p.Cursor
}

type ListTestResult struct {
	Items      []*Item
	NextCursor string
}

func (r *ListTestResult) nextCursorPtr() *string {
	return &r.NextCursor
}

var allItems = []*Item{
	{"alpha", "val-A"},
	{"bravo", "val-B"},
	{"charlie", "val-C"},
	{"delta", "val-D"},
	{"echo", "val-E"},
	{"foxtrot", "val-F"},
	{"golf", "val-G"},
	{"hotel", "val-H"},
	{"india", "val-I"},
	{"juliet", "val-J"},
	{"kilo", "val-K"},
}

// generatePaginatedResults is a helper to create a sequence of mock responses for pagination.
// It simulates a server returning items in pages based on a given page size.
func generatePaginatedResults(all []*Item, pageSize int) []*ListTestResult {
	if len(all) == 0 {
		return []*ListTestResult{{Items: []*Item{}, NextCursor: ""}}
	}
	if pageSize <= 0 {
		panic("pageSize must be greater than 0")
	}
	numPages := (len(all) + pageSize - 1) / pageSize // Ceiling division
	var results []*ListTestResult
	for i := range numPages {
		startIndex := i * pageSize
		endIndex := min(startIndex+pageSize, len(all)) // Use min to prevent out of bounds
		nextCursor := ""
		if endIndex < len(all) { // If there are more items after this page
			nextCursor = fmt.Sprintf("cursor_%d", endIndex)
		}
		results = append(results, &ListTestResult{Items: all[startIndex:endIndex], NextCursor: nextCursor})
	}
	return results
}

func TestClientPaginateBasic(t *testing.T) {
	ctx := context.Background()
	testCases := []struct {
		name          string
		results       []*ListTestResult
		mockError     error
		initialParams *ListTestParams
		expected      []*Item
		expectError   bool
	}{
		{
			name:     "SinglePageAllItems",
			results:  generatePaginatedResults(allItems, len(allItems)),
			expected: allItems,
		},
		{
			name:     "MultiplePages",
			results:  generatePaginatedResults(allItems, 3),
			expected: allItems,
		},
		{
			name:     "EmptyResults",
			results:  generatePaginatedResults([]*Item{}, 10),
			expected: nil,
		},
		{
			name:        "ListFuncReturnsErrorImmediately",
			results:     []*ListTestResult{{}},
			mockError:   fmt.Errorf("API error on first call"),
			expected:    nil,
			expectError: true,
		},
		{
			name:          "InitialCursorProvided",
			initialParams: &ListTestParams{Cursor: "cursor_2"},
			results:       generatePaginatedResults(allItems[2:], 3),
			expected:      allItems[2:],
		},
		{
			name:          "CursorBeyondAllItems",
			initialParams: &ListTestParams{Cursor: "cursor_999"},
			results:       []*ListTestResult{{Items: []*Item{}, NextCursor: ""}},
			expected:      nil,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			listFunc := func(ctx context.Context, params *ListTestParams) (*ListTestResult, error) {
				if len(tc.results) == 0 {
					t.Fatalf("listFunc called but no more results defined for test case %q", tc.name)
				}
				res := tc.results[0]
				tc.results = tc.results[1:]
				var err error
				if tc.mockError != nil {
					err = tc.mockError
				}
				return res, err
			}

			params := tc.initialParams
			if tc.initialParams == nil {
				params = &ListTestParams{}
			}

			var gotItems []*Item
			var iterationErr error
			seq := paginate(ctx, params, listFunc, func(r *ListTestResult) []*Item { return r.Items })
			for item, err := range seq {
				if err != nil {
					iterationErr = err
					break
				}
				gotItems = append(gotItems, item)
			}
			if tc.expectError {
				if iterationErr == nil {
					t.Errorf("paginate() expected an error during iteration, but got none")
				}
			} else {
				if iterationErr != nil {
					t.Errorf("paginate() got: %v, want: nil", iterationErr)
				}
			}
			if diff := cmp.Diff(tc.expected, gotItems, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("paginate() mismatch (-want +got):\n%s", diff)
			}
		})
	}
}

func TestClientPaginateVariousPageSizes(t *testing.T) {
	ctx := context.Background()
	for i := 1; i < len(allItems)+1; i++ {
		testname := fmt.Sprintf("PageSize=%d", i)
		t.Run(testname, func(t *testing.T) {
			results := generatePaginatedResults(allItems, i)
			listFunc := func(ctx context.Context, params *ListTestParams) (*ListTestResult, error) {
				res := results[0]
				results = results[1:]
				return res, nil
			}
			var gotItems []*Item
			seq := paginate(ctx, &ListTestParams{}, listFunc, func(r *ListTestResult) []*Item { return r.Items })
			for item, err := range seq {
				if err != nil {
					t.Fatalf("paginate() unexpected error during iteration: %v", err)
				}
				gotItems = append(gotItems, item)
			}
			if diff := cmp.Diff(allItems, gotItems, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("paginate() mismatch (-want +got):\n%s", diff)
			}
		})
	}
}


================================================
FILE: internal/mcp/cmd.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"io"
	"os/exec"
	"syscall"
	"time"
)

// A CommandTransport is a [Transport] that runs a command and communicates
// with it over stdin/stdout, using newline-delimited JSON.
type CommandTransport struct {
	cmd *exec.Cmd
}

// NewCommandTransport returns a [CommandTransport] that runs the given command
// and communicates with it over stdin/stdout.
//
// The resulting transport takes ownership of the command, starting it during
// [CommandTransport.Connect], and stopping it when the connection is closed.
func NewCommandTransport(cmd *exec.Cmd) *CommandTransport {
	return &CommandTransport{cmd}
}

// Connect starts the command, and connects to it over stdin/stdout.
func (t *CommandTransport) Connect(ctx context.Context) (Connection, error) {
	stdout, err := t.cmd.StdoutPipe()
	if err != nil {
		return nil, err
	}
	stdout = io.NopCloser(stdout) // close the connection by closing stdin, not stdout
	stdin, err := t.cmd.StdinPipe()
	if err != nil {
		return nil, err
	}
	if err := t.cmd.Start(); err != nil {
		return nil, err
	}
	return newIOConn(&pipeRWC{t.cmd, stdout, stdin}), nil
}

// A pipeRWC is an io.ReadWriteCloser that communicates with a subprocess over
// stdin/stdout pipes.
type pipeRWC struct {
	cmd    *exec.Cmd
	stdout io.ReadCloser
	stdin  io.WriteCloser
}

func (s *pipeRWC) Read(p []byte) (n int, err error) {
	return s.stdout.Read(p)
}

func (s *pipeRWC) Write(p []byte) (n int, err error) {
	return s.stdin.Write(p)
}

// Close closes the input stream to the child process, and awaits normal
// termination of the command. If the command does not exit, it is signalled to
// terminate, and then eventually killed.
func (s *pipeRWC) Close() error {
	// Spec:
	// "For the stdio transport, the client SHOULD initiate shutdown by:...

	// "...First, closing the input stream to the child process (the server)"
	if err := s.stdin.Close(); err != nil {
		return fmt.Errorf("closing stdin: %v", err)
	}
	resChan := make(chan error, 1)
	go func() {
		resChan <- s.cmd.Wait()
	}()
	// "...Waiting for the server to exit, or sending SIGTERM if the server does not exit within a reasonable time"
	wait := func() (error, bool) {
		select {
		case err := <-resChan:
			return err, true
		case <-time.After(5 * time.Second):
		}
		return nil, false
	}
	if err, ok := wait(); ok {
		return err
	}
	// Note the condition here: if sending SIGTERM fails, don't wait and just
	// move on to SIGKILL.
	if err := s.cmd.Process.Signal(syscall.SIGTERM); err == nil {
		if err, ok := wait(); ok {
			return err
		}
	}
	// "...Sending SIGKILL if the server does not exit within a reasonable time after SIGTERM"
	if err := s.cmd.Process.Kill(); err != nil {
		return err
	}
	if err, ok := wait(); ok {
		return err
	}
	return fmt.Errorf("unresponsive subprocess")
}


================================================
FILE: internal/mcp/cmd_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"log"
	"os"
	"os/exec"
	"runtime"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/internal/mcp"
)

const runAsServer = "_MCP_RUN_AS_SERVER"

func TestMain(m *testing.M) {
	if os.Getenv(runAsServer) != "" {
		os.Unsetenv(runAsServer)
		runServer()
		return
	}
	os.Exit(m.Run())
}

func runServer() {
	ctx := context.Background()

	server := mcp.NewServer("greeter", "v0.0.1", nil)
	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))

	if err := server.Run(ctx, mcp.NewStdioTransport()); err != nil {
		log.Fatal(err)
	}
}

func TestCmdTransport(t *testing.T) {
	// Conservatively, limit to major OS where we know that os.Exec is
	// supported.
	switch runtime.GOOS {
	case "darwin", "linux", "windows":
	default:
		t.Skip("unsupported OS")
	}

	ctx := t.Context()

	exe, err := os.Executable()
	if err != nil {
		t.Fatal(err)
	}
	cmd := exec.Command(exe)
	cmd.Env = append(os.Environ(), runAsServer+"=true")

	client := mcp.NewClient("client", "v0.0.1", nil)
	session, err := client.Connect(ctx, mcp.NewCommandTransport(cmd))
	if err != nil {
		log.Fatal(err)
	}
	got, err := session.CallTool(ctx, &mcp.CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "user"},
	})
	if err != nil {
		log.Fatal(err)
	}
	want := &mcp.CallToolResult{
		Content: []*mcp.Content{{Type: "text", Text: "Hi user"}},
	}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("greet returned unexpected content (-want +got):\n%s", diff)
	}
	if err := session.Close(); err != nil {
		t.Fatalf("closing server: %v", err)
	}
}


================================================
FILE: internal/mcp/conformance_go124_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build goexperiment.synctest

package mcp

import (
	"testing"
	"testing/synctest"
)

func runSyncTest(t *testing.T, f func(t *testing.T)) {
	synctest.Run(func() { f(t) })
}


================================================
FILE: internal/mcp/conformance_go125_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.25

package mcp

import (
	"testing"
	"testing/synctest"
)

func runSyncTest(t *testing.T, f func(t *testing.T)) {
	synctest.Test(t, f)
}


================================================
FILE: internal/mcp/conformance_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build goexperiment.synctest || go1.25

package mcp

import (
	"bytes"
	"encoding/json"
	"errors"
	"flag"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"testing/synctest"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/txtar"
)

var update = flag.Bool("update", false, "if set, update conformance test data")

// A conformance test checks JSON-level conformance of a test server or client.
// This allows us to confirm that we can handle the input or output of other
// SDKs, even if they behave differently at the JSON level (for example, have
// different behavior with respect to optional fields).
//
// The client and server fields hold an encoded sequence of JSON-RPC messages.
//
// For server tests, the client messages are a sequence of messages to be sent
// from the (synthetic) client and the server messages are the expected
// messages to be received from the real server.
//
// For client tests, it's the other way around: server messages are synthetic,
// and client messages are expected from the real client.
//
// Conformance tests are loaded from txtar-encoded testdata files. Run the test
// with -update to have the test runner update the expected output, which may
// be client or server depending on the perspective of the test.
type conformanceTest struct {
	name                      string           // test name
	path                      string           // path to test file
	archive                   *txtar.Archive   // raw archive, for updating
	tools, prompts, resources []string         // named features to include
	client                    []JSONRPCMessage // client messages
	server                    []JSONRPCMessage // server messages
}

// TODO(rfindley): add client conformance tests.

func TestServerConformance(t *testing.T) {
	var tests []*conformanceTest
	dir := filepath.Join("testdata", "conformance", "server")
	if err := filepath.WalkDir(dir, func(path string, _ fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if strings.HasSuffix(path, ".txtar") {
			test, err := loadConformanceTest(dir, path)
			if err != nil {
				return fmt.Errorf("%s: %v", path, err)
			}
			tests = append(tests, test)
		}
		return nil
	}); err != nil {
		t.Fatal(err)
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			// We use synctest here because in general, there is no way to know when the
			// server is done processing any notifications. As long as our server doesn't
			// do background work, synctest provides an easy way for us to detect when the
			// server is done processing.
			//
			// By comparison, gopls has a complicated framework based on progress
			// reporting and careful accounting to detect when all 'expected' work
			// on the server is complete.
			runSyncTest(t, func(t *testing.T) { runServerTest(t, test) })

			// TODO: in 1.25, use the following instead:
			// synctest.Test(t, func(t *testing.T) {
			// 	runServerTest(t, test)
			// })
		})
	}
}

// runServerTest runs the server conformance test.
// It must be executed in a synctest bubble.
func runServerTest(t *testing.T, test *conformanceTest) {
	ctx := t.Context()
	// Construct the server based on features listed in the test.
	s := NewServer("testServer", "v1.0.0", nil)
	add(tools, s.AddTools, test.tools...)
	add(prompts, s.AddPrompts, test.prompts...)
	add(resources, s.AddResources, test.resources...)

	// Connect the server, and connect the client stream,
	// but don't connect an actual client.
	cTransport, sTransport := NewInMemoryTransports()
	ss, err := s.Connect(ctx, sTransport)
	if err != nil {
		t.Fatal(err)
	}
	cStream, err := cTransport.Connect(ctx)
	if err != nil {
		t.Fatal(err)
	}

	writeMsg := func(msg JSONRPCMessage) {
		if err := cStream.Write(ctx, msg); err != nil {
			t.Fatalf("Write failed: %v", err)
		}
	}

	var (
		serverMessages []JSONRPCMessage
		outRequests    []*JSONRPCRequest
		outResponses   []*JSONRPCResponse
	)

	// Separate client requests and responses; we use them differently.
	for _, msg := range test.client {
		switch msg := msg.(type) {
		case *JSONRPCRequest:
			outRequests = append(outRequests, msg)
		case *JSONRPCResponse:
			outResponses = append(outResponses, msg)
		default:
			t.Fatalf("bad message type %T", msg)
		}
	}

	// nextResponse handles incoming requests and notifications, and returns the
	// next incoming response.
	nextResponse := func() (*JSONRPCResponse, error, bool) {
		for {
			msg, err := cStream.Read(ctx)
			if err != nil {
				// TODO(rfindley): we don't document (or want to document) that the in
				// memory transports use a net.Pipe. How can users detect this failure?
				// Should we promote it to EOF?
				if errors.Is(err, io.ErrClosedPipe) {
					err = nil
				}
				return nil, err, false
			}
			serverMessages = append(serverMessages, msg)
			if req, ok := msg.(*JSONRPCRequest); ok && req.ID.IsValid() {
				// Pair up the next outgoing response with this request.
				// We assume requests arrive in the same order every time.
				if len(outResponses) == 0 {
					t.Fatalf("no outgoing response for request %v", req)
				}
				outResponses[0].ID = req.ID
				writeMsg(outResponses[0])
				outResponses = outResponses[1:]
				continue
			}
			return msg.(*JSONRPCResponse), nil, true
		}
	}

	// Synthetic peer interacts with real peer.
	for _, req := range outRequests {
		writeMsg(req)
		if req.ID.IsValid() {
			// A request (as opposed to a notification). Wait for the response.
			res, err, ok := nextResponse()
			if err != nil {
				t.Fatalf("reading server messages failed: %v", err)
			}
			if !ok {
				t.Fatalf("missing response for request %v", req)
			}
			if res.ID != req.ID {
				t.Fatalf("out-of-order response %v to request %v", req, res)
			}
		}
	}
	// There might be more notifications or requests, but there shouldn't be more
	// responses.
	// Run this in a goroutine so the current thread can wait for it.
	var extra *JSONRPCResponse
	go func() {
		extra, err, _ = nextResponse()
	}()
	// Before closing the stream, wait for all messages to be processed.
	synctest.Wait()
	if err != nil {
		t.Fatalf("reading server messages failedd: %v", err)
	}
	if extra != nil {
		t.Fatalf("got extra response: %v", extra)
	}
	if err := cStream.Close(); err != nil {
		t.Fatalf("Stream.Close failed: %v", err)
	}
	ss.Wait() // ignore error

	// Handle server output. If -update is set, write the 'server' file.
	// Otherwise, compare with expected.
	if *update {
		arch := &txtar.Archive{
			Comment: test.archive.Comment,
		}
		var buf bytes.Buffer
		for _, msg := range serverMessages {
			data, err := jsonrpc2.EncodeIndent(msg, "", "\t")
			if err != nil {
				t.Fatalf("jsonrpc2.EncodeIndent failed: %v", err)
			}
			buf.Write(data)
			buf.WriteByte('\n')
		}
		serverFile := txtar.File{Name: "server", Data: buf.Bytes()}
		seenServer := false // replace or append the 'server' file
		for _, f := range test.archive.Files {
			if f.Name == "server" {
				seenServer = true
				arch.Files = append(arch.Files, serverFile)
			} else {
				arch.Files = append(arch.Files, f)
			}
		}
		if !seenServer {
			arch.Files = append(arch.Files, serverFile)
		}
		if err := os.WriteFile(test.path, txtar.Format(arch), 0o666); err != nil {
			t.Fatalf("os.WriteFile(%q) failed: %v", test.path, err)
		}
	} else {
		// JSONRPCMessages are not comparable, so we instead compare lines of JSON.
		transform := cmpopts.AcyclicTransformer("toJSON", func(msg JSONRPCMessage) []string {
			encoded, err := jsonrpc2.EncodeIndent(msg, "", "\t")
			if err != nil {
				t.Fatal(err)
			}
			return strings.Split(string(encoded), "\n")
		})
		if diff := cmp.Diff(test.server, serverMessages, transform); diff != "" {
			t.Errorf("Mismatching server messages (-want +got):\n%s", diff)
		}
	}
}

// loadConformanceTest loads one conformance test from the given path contained
// in the root dir.
func loadConformanceTest(dir, path string) (*conformanceTest, error) {
	content, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	test := &conformanceTest{
		name:    strings.TrimPrefix(path, dir+string(filepath.Separator)),
		path:    path,
		archive: txtar.Parse(content),
	}
	if len(test.archive.Files) == 0 {
		return nil, fmt.Errorf("txtar archive %q has no '-- filename --' sections", path)
	}

	// decodeMessages loads JSON-RPC messages from the archive file.
	decodeMessages := func(data []byte) ([]JSONRPCMessage, error) {
		dec := json.NewDecoder(bytes.NewReader(data))
		var res []JSONRPCMessage
		for dec.More() {
			var raw json.RawMessage
			if err := dec.Decode(&raw); err != nil {
				return nil, err
			}
			m, err := jsonrpc2.DecodeMessage(raw)
			if err != nil {
				return nil, err
			}
			res = append(res, m)
		}
		return res, nil
	}
	// loadFeatures loads lists of named features from the archive file.
	loadFeatures := func(data []byte) []string {
		var feats []string
		for line := range strings.Lines(string(data)) {
			if f := strings.TrimSpace(line); f != "" {
				feats = append(feats, f)
			}
		}
		return feats
	}

	seen := make(map[string]bool) // catch accidentally duplicate files
	for _, f := range test.archive.Files {
		if seen[f.Name] {
			return nil, fmt.Errorf("duplicate file name %q", f.Name)
		}
		seen[f.Name] = true
		switch f.Name {
		case "tools":
			test.tools = loadFeatures(f.Data)
		case "prompts":
			test.prompts = loadFeatures(f.Data)
		case "resources":
			test.resources = loadFeatures(f.Data)
		case "client":
			test.client, err = decodeMessages(f.Data)
			if err != nil {
				return nil, fmt.Errorf("txtar archive %q contains bad -- client -- section: %v", path, err)
			}
		case "server":
			test.server, err = decodeMessages(f.Data)
			if err != nil {
				return nil, fmt.Errorf("txtar archive %q contains bad -- server -- section: %v", path, err)
			}
		default:
			return nil, fmt.Errorf("txtar archive %q contains unexpected file %q", path, f.Name)
		}
	}

	return test, nil
}


================================================
FILE: internal/mcp/content.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"encoding/json"
	"errors"
	"fmt"
)

// Content is the wire format for content.
// It represents the protocol types TextContent, ImageContent, AudioContent
// and EmbeddedResource.
// Use [NewTextContent], [NewImageContent], [NewAudioContent] or [NewResourceContent]
// to create one.
//
// The Type field must be one of "text", "image", "audio" or "resource". The
// constructors above populate this field appropriately.
// Although at most one of Text, Data, and Resource should be non-zero, consumers of Content
// use the Type field to determine which value to use; values in the other fields are ignored.
type Content struct {
	Type        string            `json:"type"`
	Text        string            `json:"text,omitempty"`
	MIMEType    string            `json:"mimeType,omitempty"`
	Data        []byte            `json:"data,omitempty"`
	Resource    *ResourceContents `json:"resource,omitempty"`
	Annotations *Annotations      `json:"annotations,omitempty"`
}

func (c *Content) UnmarshalJSON(data []byte) error {
	type wireContent Content // for naive unmarshaling
	var c2 wireContent
	if err := json.Unmarshal(data, &c2); err != nil {
		return err
	}
	switch c2.Type {
	case "text", "image", "audio", "resource":
	default:
		return fmt.Errorf("unrecognized content type %s", c.Type)
	}
	*c = Content(c2)
	return nil
}

// NewTextContent creates a [Content] with text.
func NewTextContent(text string) *Content {
	return &Content{Type: "text", Text: text}
}

// NewImageContent creates a [Content] with image data.
func NewImageContent(data []byte, mimeType string) *Content {
	return &Content{Type: "image", Data: data, MIMEType: mimeType}
}

// NewAudioContent creates a [Content] with audio data.
func NewAudioContent(data []byte, mimeType string) *Content {
	return &Content{Type: "audio", Data: data, MIMEType: mimeType}
}

// NewResourceContent creates a [Content] with an embedded resource.
func NewResourceContent(resource *ResourceContents) *Content {
	return &Content{Type: "resource", Resource: resource}
}

// ResourceContents represents the union of the spec's {Text,Blob}ResourceContents types.
// See https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/schema/2025-03-26/schema.ts#L524-L551
// for the inheritance structure.

// A ResourceContents is either a TextResourceContents or a BlobResourceContents.
// Use [NewTextResourceContents] or [NextBlobResourceContents] to create one.
type ResourceContents struct {
	URI      string `json:"uri"` // resource location; must not be empty
	MIMEType string `json:"mimeType,omitempty"`
	Text     string `json:"text"`
	Blob     []byte `json:"blob,omitempty"` // if nil, then text; else blob
}

func (r ResourceContents) MarshalJSON() ([]byte, error) {
	// TODO(adonovan): now we can assume Go 1.24, use omitzero for Blob and avoid this method.
	if r.URI == "" {
		return nil, errors.New("ResourceContents missing URI")
	}
	if r.Blob == nil {
		// Text. Marshal normally.
		type wireResourceContents ResourceContents // (lacks MarshalJSON method)
		return json.Marshal((wireResourceContents)(r))
	}
	// Blob.
	if r.Text != "" {
		return nil, errors.New("ResourceContents has non-zero Text and Blob fields")
	}
	// r.Blob may be the empty slice, so marshal with an alternative definition.
	br := struct {
		URI      string `json:"uri,omitempty"`
		MIMEType string `json:"mimeType,omitempty"`
		Blob     []byte `json:"blob"`
	}{
		URI:      r.URI,
		MIMEType: r.MIMEType,
		Blob:     r.Blob,
	}
	return json.Marshal(br)
}

// NewTextResourceContents returns a [ResourceContents] containing text.
func NewTextResourceContents(uri, mimeType, text string) *ResourceContents {
	return &ResourceContents{
		URI:      uri,
		MIMEType: mimeType,
		Text:     text,
		// Blob is nil, indicating this is a TextResourceContents.
	}
}

// NewBlobResourceContents returns a [ResourceContents] containing a byte slice.
func NewBlobResourceContents(uri, mimeType string, blob []byte) *ResourceContents {
	// The only way to distinguish text from blob is a non-nil Blob field.
	if blob == nil {
		blob = []byte{}
	}
	return &ResourceContents{
		URI:      uri,
		MIMEType: mimeType,
		Blob:     blob,
	}
}


================================================
FILE: internal/mcp/content_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"encoding/json"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/internal/mcp"
)

func TestContent(t *testing.T) {
	tests := []struct {
		in   *mcp.Content
		want string // json serialization
	}{
		{mcp.NewTextContent("hello"), `{"type":"text","text":"hello"}`},
		{
			mcp.NewImageContent([]byte("a1b2c3"), "image/png"),
			`{"type":"image","mimeType":"image/png","data":"YTFiMmMz"}`,
		},
		{
			mcp.NewAudioContent([]byte("a1b2c3"), "audio/wav"),
			`{"type":"audio","mimeType":"audio/wav","data":"YTFiMmMz"}`,
		},
		{
			mcp.NewResourceContent(
				mcp.NewTextResourceContents("file://foo", "text", "abc"),
			),
			`{"type":"resource","resource":{"uri":"file://foo","mimeType":"text","text":"abc"}}`,
		},
		{
			mcp.NewResourceContent(
				mcp.NewBlobResourceContents("file://foo", "image/png", []byte("a1b2c3")),
			),
			`{"type":"resource","resource":{"uri":"file://foo","mimeType":"image/png","blob":"YTFiMmMz"}}`,
		},
	}

	for _, test := range tests {
		got, err := json.Marshal(test.in)
		if err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(test.want, string(got)); diff != "" {
			t.Errorf("json.Marshal(%v) mismatch (-want +got):\n%s", test.in, diff)
		}
		var out *mcp.Content
		if err := json.Unmarshal(got, &out); err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(test.in, out); diff != "" {
			t.Errorf("json.Unmarshal(%q) mismatch (-want +got):\n%s", string(got), diff)
		}
	}
}

func TestResourceContents(t *testing.T) {
	for _, tt := range []struct {
		rc   mcp.ResourceContents
		want string // marshaled JSON
	}{
		{
			mcp.ResourceContents{URI: "u", Text: "t"},
			`{"uri":"u","text":"t"}`,
		},
		{
			mcp.ResourceContents{URI: "u", MIMEType: "m", Text: "t"},
			`{"uri":"u","mimeType":"m","text":"t"}`,
		},
		{
			mcp.ResourceContents{URI: "u", Text: "", Blob: nil},
			`{"uri":"u","text":""}`,
		},
		{
			mcp.ResourceContents{URI: "u", Blob: []byte{}},
			`{"uri":"u","blob":""}`,
		},
		{
			mcp.ResourceContents{URI: "u", Blob: []byte{1}},
			`{"uri":"u","blob":"AQ=="}`,
		},
	} {
		data, err := json.Marshal(tt.rc)
		if err != nil {
			t.Fatal(err)
		}
		if got := string(data); got != tt.want {
			t.Errorf("%#v:\ngot  %s\nwant %s", tt.rc, got, tt.want)
		}
		var urc mcp.ResourceContents
		if err := json.Unmarshal(data, &urc); err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(tt.rc, urc); diff != "" {
			t.Errorf("mismatch (-want, +got):\n%s", diff)
		}
	}
}


================================================
FILE: internal/mcp/create-repo.sh
================================================
#!/bin/bash

# This script creates an MCP SDK repo from x/tools/internal/mcp (and friends).
# It will be used as a one-off to create github.com/modelcontextprotocol/go-sdk.
#
# Requires https://github.com/newren/git-filter-repo.

set -eu

# Check if exactly one argument is provided
if [ "$#" -ne 1 ]; then
  echo "create-repo.sh: create a standalone mcp SDK repo from x/tools"
  echo "Usage: $0 <mcp repo destination>"
  exit 1
fi >&2

src=$(go list -m -f {{.Dir}} golang.org/x/tools)
dest="$1"

echo "Filtering MCP commits from ${src} to ${dest}..." >&2

startdir=$(pwd)
tempdir=$(mktemp -d)
function cleanup {
  echo "cleaning up ${tempdir}"
  rm -rf "$tempdir"
} >&2
trap cleanup EXIT SIGINT

echo "Checking out to ${tempdir}"

git clone --bare "${src}" "${tempdir}"
git -C "${tempdir}" --git-dir=. filter-repo \
  --path internal/mcp/jsonschema --path-rename internal/mcp/jsonschema:jsonschema \
  --path internal/mcp/design --path-rename internal/mcp/design:design \
  --path internal/mcp/examples --path-rename internal/mcp/examples:examples \
  --path internal/mcp/internal --path-rename internal/mcp/internal:internal \
  --path internal/mcp/README.md --path-rename internal/mcp/README.md:README.md \
  --path internal/mcp/CONTRIBUTING.md --path-rename internal/mcp/CONTRIBUTING.md:CONTRIBUTING.md \
  --path internal/mcp --path-rename internal/mcp:mcp \
  --path internal/jsonrpc2_v2 --path-rename internal/jsonrpc2_v2:internal/jsonrpc2 \
  --path internal/xcontext \
  --replace-text "${startdir}/mcp-repo-replace.txt" \
  --force
mkdir ${dest}
cd "${dest}"
git init

cat << EOF > LICENSE
MIT License

Copyright (c) 2025 Go MCP SDK Authors

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.
EOF

git add LICENSE && git commit -m "Initial commit: add LICENSE"
git remote add filtered_source "${tempdir}"
git pull filtered_source master --allow-unrelated-histories
git remote remove filtered_source
go mod init github.com/modelcontextprotocol/go-sdk && go get go@1.23.0
go mod tidy
git add go.mod go.sum
git commit -m "all: add go.mod and go.sum file"


================================================
FILE: internal/mcp/design/design.md
================================================
# Go SDK Design

This document discusses the design of a Go SDK for the [model context protocol](https://modelcontextprotocol.io/specification/2025-03-26). The [golang.org/x/tools/internal/mcp](https://pkg.go.dev/golang.org/x/tools/internal/mcp@master) package contains a prototype that we built to explore the MCP design space. Many of the ideas there are present in this document. However, we have diverged from and expanded on the APIs of that prototype, and this document should be considered canonical.

## Similarities and differences with mark3labs/mcp-go (and others)

The most popular unofficial MCP SDK for Go is [mark3labs/mcp-go](https://pkg.go.dev/github.com/mark3labs/mcp-go). As of this writing, it is imported by over 400 packages that span over 200 modules.

We admire mcp-go, and where possible tried to align with its design. However, the APIs here diverge in a number of ways in order to keep the official SDK minimal, allow for future spec evolution, and support additional features. We have noted significant differences from mcp-go in the sections below. Although the API here is not compatible with mcp-go, translating between them should be straightforward in most cases. (Later, we will provide a detailed translation guide.)

Thank you to everyone who contributes to mcp-go and other Go SDKs. We hope that we can collaborate to leverage all that we've learned about MCP and Go in an official SDK.

# Requirements

These may be obvious, but it's worthwhile to define goals for an official MCP SDK. An official SDK should aim to be:

- **complete**: it should be possible to implement every feature of the MCP spec, and these features should conform to all of the semantics described by the spec.
- **idiomatic**: as much as possible, MCP features should be modeled using features of the Go language and its standard library. Additionally, the SDK should repeat idioms from similar domains.
- **robust**: the SDK itself should be well tested and reliable, and should enable easy testability for its users.
- **future-proof**: the SDK should allow for future evolution of the MCP spec, in such a way that we can (as much as possible) avoid incompatible changes to the SDK API.
- **extensible**: to best serve the previous four concerns, the SDK should be minimal. However, it should admit extensibility using (for example) simple interfaces, middleware, or hooks.

# Design

In the sections below, we visit each aspect of the MCP spec, in approximately the order they are presented by the [official spec](https://modelcontextprotocol.io/specification/2025-03-26) For each, we discuss considerations for the Go implementation, and propose a Go API.

## Foundations

### Package layout

In the sections that follow, it is assumed that most of the MCP API lives in a single shared package, the `mcp` package. This is inconsistent with other MCP SDKs, but is consistent with Go packages like `net/http`, `net/rpc`, or `google.golang.org/grpc`. We believe that having a single package aids discoverability in package documentation and in the IDE. Furthermore, it avoids arbitrary decisions about package structure that may be rendered inaccurate by future evolution of the spec.

Functionality that is not directly related to MCP (like jsonschema or jsonrpc2) belongs in a separate package.

Therefore, this is the core package layout, assuming github.com/modelcontextprotocol/go-sdk as the module path.

- `github.com/modelcontextprotocol/go-sdk/mcp`: the bulk of the user facing API
- `github.com/modelcontextprotocol/go-sdk/jsonschema`: a jsonschema implementation, with validation
- `github.com/modelcontextprotocol/go-sdk/internal/jsonrpc2`: a fork of x/tools/internal/jsonrpc2_v2

The JSON-RPC implementation is hidden, to avoid tight coupling. As described in the next section, the only aspects of JSON-RPC that need to be exposed in the SDK are the message types, for the purposes of defining custom transports. We can expose these types by promoting them from the `mcp` package using aliases or wrappers.

**Difference from mcp-go**: Our `mcp` package includes all the functionality of mcp-go's `mcp`, `client`, `server` and `transport` packages.

### JSON-RPC and Transports

The MCP is defined in terms of client-server communication over bidirectional JSON-RPC message connections. Specifically, version `2025-03-26` of the spec defines two transports:

- **stdio**: communication with a subprocess over stdin/stdout.
- **streamable http**: communication over a relatively complicated series of text/event-stream GET and HTTP POST requests.

Additionally, version `2024-11-05` of the spec defined a simpler (yet stateful) HTTP transport:

- **sse**: client issues a hanging GET request and receives messages via `text/event-stream`, and sends messages via POST to a session endpoint.

Furthermore, the spec [states](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#custom-transports) that it must be possible for users to define their own custom transports.

Given the diversity of the transport implementations, they can be challenging to abstract. However, since JSON-RPC requires a bidirectional connection, we can use this to model the MCP transport abstraction:

```go
type (
	JSONRPCID       = jsonrpc2.ID
	JSONRPCMessage  = jsonrpc2.Message
	JSONRPCRequest  = jsonrpc2.Request
	JSONRPCResponse = jsonrpc2.Response
)

// A Transport is used to create a bidirectional connection between MCP client
// and server.
type Transport interface {
    Connect(ctx context.Context) (Connection, error)
}

// A Connection is a bidirectional jsonrpc2 connection.
type Connection interface {
    Read(ctx context.Context) (JSONRPCMessage, error)
    Write(ctx context.Context, JSONRPCMessage) error
    Close() error
}
```

Methods accept a Go `Context` and return an `error`, as is idiomatic for APIs that do I/O.

A `Transport` is something that connects a logical JSON-RPC connection, and nothing more. Connections must be closeable in order to implement client and server shutdown, and therefore conform to the `io.Closer` interface.

Other SDKs define higher-level transports, with, for example, methods to send a notification or make a call. Those are jsonrpc2 operations on top of the logical connection, and the lower-level interface is easier to implement in most cases, which means it is easier to implement custom transports.

For our prototype, we've used an internal `jsonrpc2` package based on the Go language server `gopls`, which we propose to fork for the MCP SDK. It already handles concerns like client/server connection, request lifecycle, cancellation, and shutdown.

**Differences from mcp-go**: The Go team has a battle-tested JSON-RPC implementation that we use for gopls, our Go LSP server. We are using the new version of this library as part of our MCP SDK. It handles all JSON-RPC 2.0 features, including cancellation.

The `Transport` interface here is lower-level than that of mcp-go, but serves a similar purpose. We believe the lower-level interface is easier to implement.

#### stdio transports

In the MCP Spec, the **stdio** transport uses newline-delimited JSON to communicate over stdin/stdout. It's possible to model both client side and server side of this communication with a shared type that communicates over an `io.ReadWriteCloser`. However, for the purposes of future-proofing, we should use a different types for client and server stdio transport.

The `CommandTransport` is the client side of the stdio transport, and connects by starting a command and streaming JSON-RPC messages over stdin/stdout.

```go
// A CommandTransport is a [Transport] that runs a command and communicates
// with it over stdin/stdout, using newline-delimited JSON.
type CommandTransport struct { /* unexported fields */ }

// NewCommandTransport returns a [CommandTransport] that runs the given command
// and communicates with it over stdin/stdout.
func NewCommandTransport(cmd *exec.Command) *CommandTransport

// Connect starts the command, and connects to it over stdin/stdout.
func (*CommandTransport) Connect(ctx context.Context) (Connection, error) {
```

The `StdioTransport` is the server side of the stdio transport, and connects by binding to `os.Stdin` and `os.Stdout`.

```go
// A StdioTransport is a [Transport] that communicates using newline-delimited
// JSON over stdin/stdout.
type StdioTransport struct { /* unexported fields */ }

func NewStdioTransport() *StdioTransport

func (t *StdioTransport) Connect(context.Context) (Connection, error)
```

#### HTTP transports

The HTTP transport APIs are even more asymmetrical. Since connections are initiated via HTTP requests, the client developer will create a transport, but the server developer will typically install an HTTP handler. Internally, the HTTP handler will create a logical transport for each new client connection.

Importantly, since they serve many connections, the HTTP handlers must accept a callback to get an MCP server for each new session. As described below, MCP servers can optionally connect to multiple clients. This allows customization of per-session servers: if the MCP server is stateless, the user can return the same MCP server for each connection. On the other hand, if any per-session customization is required, it is possible by returning a different `Server` instance for each connection.

```go
// SSEHTTPHandler is an http.Handler that serves SSE-based MCP sessions as defined by
// the 2024-11-05 version of the MCP protocol.
type SSEHTTPHandler struct { /* unexported fields */ }

// NewSSEHTTPHandler returns a new [SSEHTTPHandler] that is ready to serve HTTP.
//
// The getServer function is used to bind created servers for new sessions. It
// is OK for getServer to return the same server multiple times.
func NewSSEHTTPHandler(getServer func(request *http.Request) *Server) *SSEHTTPHandler

func (*SSEHTTPHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)

// Close prevents the SSEHTTPHandler from accepting new sessions, closes active
// sessions, and awaits their graceful termination.
func (*SSEHTTPHandler) Close() error
```

Notably absent are options to hook into low-level request handling for the purposes of authentication or context injection. These concerns are instead handled using standard HTTP middleware patterns. For middleware at the level of the MCP protocol, see [Middleware](#Middleware) below.

By default, the SSE handler creates messages endpoints with the `?sessionId=...` query parameter. Users that want more control over the management of sessions and session endpoints may write their own handler, and create `SSEServerTransport` instances themselves for incoming GET requests.

```go
// A SSEServerTransport is a logical SSE session created through a hanging GET
// request.
//
// When connected, it returns the following [Connection] implementation:
//   - Writes are SSE 'message' events to the GET response.
//   - Reads are received from POSTs to the session endpoint, via
//     [SSEServerTransport.ServeHTTP].
//   - Close terminates the hanging GET.
type SSEServerTransport struct { /* ... */ }

// NewSSEServerTransport creates a new SSE transport for the given messages
// endpoint, and hanging GET response.
//
// Use [SSEServerTransport.Connect] to initiate the flow of messages.
//
// The transport is itself an [http.Handler]. It is the caller's responsibility
// to ensure that the resulting transport serves HTTP requests on the given
// session endpoint.
//
// Most callers should instead use an [SSEHandler], which transparently handles
// the delegation to SSEServerTransports.
func NewSSEServerTransport(endpoint string, w http.ResponseWriter) *SSEServerTransport

// ServeHTTP handles POST requests to the transport endpoint.
func (*SSEServerTransport) ServeHTTP(w http.ResponseWriter, req *http.Request)

// Connect sends the 'endpoint' event to the client.
// See [SSEServerTransport] for more details on the [Connection] implementation.
func (*SSEServerTransport) Connect(context.Context) (Connection, error)
```

The SSE client transport is simpler, and hopefully self-explanatory.

```go
type SSEClientTransport struct { /* ... */ }

// SSEClientTransportOptions provides options for the [NewSSEClientTransport]
// constructor.
type SSEClientTransportOptions struct {
	// HTTPClient is the client to use for making HTTP requests. If nil,
	// http.DefaultClient is used.
	HTTPClient *http.Client
}

// NewSSEClientTransport returns a new client transport that connects to the
// SSE server at the provided URL.
func NewSSEClientTransport(url string, opts *SSEClientTransportOptions) (*SSEClientTransport, error)

// Connect connects through the client endpoint.
func (*SSEClientTransport) Connect(ctx context.Context) (Connection, error)
```

The Streamable HTTP transports are similar to the SSE transport, albeit with a
more complicated implementation. For brevity, we summarize only the differences
from the equivalent SSE types:

```go
// The StreamableHTTPHandler interface is symmetrical to the SSEHTTPHandler.
type StreamableHTTPHandler struct { /* unexported fields */ }
func NewStreamableHTTPHandler(getServer func(request *http.Request) *Server) *StreamableHTTPHandler
func (*StreamableHTTPHandler) ServeHTTP(w http.ResponseWriter, req *http.Request)
func (*StreamableHTTPHandler) Close() error

// Unlike the SSE transport, the streamable transport constructor accepts a
// session ID, not an endpoint, along with the HTTP response for the request
// that created the session. It is the caller's responsibility to delegate
// requests to this session.
type StreamableServerTransport struct { /* ... */ }
func NewStreamableServerTransport(sessionID string) *StreamableServerTransport
func (*StreamableServerTransport) ServeHTTP(w http.ResponseWriter, req *http.Request)
func (*StreamableServerTransport) Connect(context.Context) (Connection, error)

// The streamable client handles reconnection transparently to the user.
type StreamableClientTransport struct { /* ... */ }

// StreamableClientTransportOptions provides options for the
// [NewStreamableClientTransport] constructor.
type StreamableClientTransportOptions struct {
	// HTTPClient is the client to use for making HTTP requests. If nil,
	// http.DefaultClient is used.
	HTTPClient *http.Client
}

func NewStreamableClientTransport(url string, opts *StreamableClientTransportOptions) *StreamableClientTransport
func (*StreamableClientTransport) Connect(context.Context) (Connection, error)
```

**Differences from mcp-go**: In mcp-go, server authors create an `MCPServer`, populate it with tools, resources and so on, and then wrap it in an `SSEServer` or `StdioServer`. Users can manage their own sessions with `RegisterSession` and `UnregisterSession`. Rather than use a server constructor to get a distinct server for each connection, there is a concept of a "session tool" that overlays tools for a specific session.

Here, we tried to differentiate the concept of a `Server`, `HTTPHandler`, and `Transport`, and provide per-session customization through either the `getServer` constructor or middleware. Additionally, individual handlers and transports here have a minimal API, and do not expose internal details. (Open question: are we oversimplifying?)

#### Other transports

We also provide a couple of transport implementations for special scenarios. An InMemoryTransport can be used when the client and server reside in the same process. A LoggingTransport is a middleware layer that logs RPC logs to a desired location, specified as an io.Writer.

```go
// An InMemoryTransport is a [Transport] that communicates over an in-memory
// network connection, using newline-delimited JSON.
type InMemoryTransport struct { /* ... */ }

// NewInMemoryTransports returns two InMemoryTransports that connect to each
// other.
func NewInMemoryTransports() (*InMemoryTransport, *InMemoryTransport)

// A LoggingTransport is a [Transport] that delegates to another transport,
// writing RPC logs to an io.Writer.
type LoggingTransport struct { /* ... */ }
func NewLoggingTransport(delegate Transport, w io.Writer) *LoggingTransport
```

### Protocol types

Types needed for the protocol are generated from the [JSON schema of the MCP spec](https://github.com/modelcontextprotocol/modelcontextprotocol/blob/main/schema/2025-03-26/schema.json).

These types will be included in the `mcp` package, but will be unexported unless they are needed for the user-facing API. Notably, JSON-RPC request types are elided, since they are handled by the `jsonrpc2` package and should not be observed by the user.

For user-provided data, we use `json.RawMessage` or `map[string]any`, depending on the use case.

For union types, which can't be represented in Go (specifically `Content` and `ResourceContents`), we prefer distinguished unions: struct types with fields corresponding to the union of all properties for union elements.

For brevity, only a few examples are shown here:

```go
type ReadResourceParams struct {
	URI string `json:"uri"`
}

type CallToolResult struct {
	Meta    Meta      `json:"_meta,omitempty"`
	Content []Content `json:"content"`
	IsError bool      `json:"isError,omitempty"`
}

// Content is the wire format for content.
//
// The Type field distinguishes the type of the content.
// At most one of Text, MIMEType, Data, and Resource is non-zero.
type Content struct {
	Type     string            `json:"type"`
	Text     string            `json:"text,omitempty"`
	MIMEType string            `json:"mimeType,omitempty"`
	Data     []byte            `json:"data,omitempty"`
	Resource *ResourceContents `json:"resource,omitempty"`
}

// NewTextContent creates a [Content] with text.
func NewTextContent(text string) *Content
// etc.
```

The `Meta` type includes a `map[string]any` for arbitrary data, and a `ProgressToken` field.

**Differences from mcp-go**: these types are largely similar, but our type generator flattens types rather than using struct embedding.

### Clients and Servers

Generally speaking, the SDK is used by creating a `Client` or `Server` instance, adding features to it, and connecting it to a peer.

However, the SDK must make a non-obvious choice in these APIs: are clients 1:1 with their logical connections? What about servers? Both clients and servers are stateful: users may add or remove roots from clients, and tools, prompts, and resources from servers. Additionally, handlers for these features may themselves be stateful, for example if a tool handler caches state from earlier requests in the session.

We believe that in the common case, any change to a client or server, such as adding a tool, is intended for all its peers. It is therefore more useful to allow multiple connections from a client, and to a server. This is similar to the `net/http` packages, in which an `http.Client` and `http.Server` each may handle multiple unrelated connections. When users add features to a client or server, all connected peers are notified of the change.

Supporting multiple connections to servers (and from clients) still allows for stateful components, as it is up to the user to decide whether or not to create distinct servers/clients for each connection. For example, if the user wants to create a distinct server for each new connection, they can do so in the `getServer` factory passed to transport handlers.

Following the terminology of the [spec](https://modelcontextprotocol.io/specification/2025-03-26/basic/transports#session-management), we call the logical connection between a client and server a "session." There must necessarily be a `ClientSession` and a `ServerSession`, corresponding to the APIs available from the client and server perspective, respectively.

```
Client                                                   Server
  ⇅                          (jsonrpc2)                     ⇅
ClientSession ⇄ Client Transport ⇄ Server Transport ⇄ ServerSession
```

Sessions are created from either `Client` or `Server` using the `Connect` method.

```go
type Client struct { /* ... */ }
func NewClient(name, version string, opts *ClientOptions) *Client
func (*Client) Connect(context.Context, Transport) (*ClientSession, error)
func (*Client) Sessions() iter.Seq[*ClientSession]
// Methods for adding/removing client features are described below.

type ClientOptions struct { /* ... */ } // described below

type ClientSession struct { /* ... */ }
func (*ClientSession) Client() *Client
func (*ClientSession) Close() error
func (*ClientSession) Wait() error
// Methods for calling through the ClientSession are described below.
// For example: ClientSession.ListTools.

type Server struct { /* ... */ }
func NewServer(name, version string, opts *ServerOptions) *Server
func (*Server) Connect(context.Context, Transport) (*ServerSession, error)
func (*Server) Sessions() iter.Seq[*ServerSession]
// Methods for adding/removing server features are described below.

type ServerOptions struct { /* ... */ } // described below

type ServerSession struct { /* ... */ }
func (*ServerSession) Server() *Server
func (*ServerSession) Close() error
func (*ServerSession) Wait() error
// Methods for calling through the ServerSession are described below.
// For example: ServerSession.ListRoots.
```

Here's an example of these APIs from the client side:

```go
client := mcp.NewClient("mcp-client", "v1.0.0", nil)
// Connect to a server over stdin/stdout
transport := mcp.NewCommandTransport(exec.Command("myserver"))
session, err := client.Connect(ctx, transport)
if err != nil { ... }
// Call a tool on the server.
content, err := session.CallTool(ctx, "greet", map[string]any{"name": "you"}, nil)
...
return session.Close()
```

A server that can handle that client call would look like this:

```go
// Create a server with a single tool.
server := mcp.NewServer("greeter", "v1.0.0", nil)
server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))
// Run the server over stdin/stdout, until the client disconnects.
transport := mcp.NewStdioTransport()
session, err := server.Connect(ctx, transport)
...
return session.Wait()
```

For convenience, we provide `Server.Run` to handle the common case of running a session until the client disconnects:

```go
func (*Server) Run(context.Context, Transport)
```

**Differences from mcp-go**: the Server APIs are similar to mcp-go, though the association between servers and transports is different. In mcp-go, a single server is bound to what we would call an `SSEHTTPHandler`, and reused for all sessions. Per-session behavior is implemented though a 'session tool' overlay. As discussed above, the transport abstraction here is differentiated from HTTP serving, and the `Server.Connect` method provides a consistent API for binding to an arbitrary transport. Servers here do not have methods for sending notifications or calls, because they are logically distinct from the `ServerSession`. In mcp-go, servers are `n:1`, but there is no abstraction of a server session: sessions are addressed in Server APIs through their `sessionID`: `SendNotificationToAllClients`, `SendNotificationToClient`, `SendNotificationToSpecificClient`.

The client API here is different, since clients and client sessions are conceptually distinct. The `ClientSession` is closer to mcp-go's notion of Client.

For both clients and servers, mcp-go uses variadic options to customize behavior, whereas an options struct is used here. We felt that in this case, an options struct would be more readable, and result in simpler package documentation.

### Spec Methods

In our SDK, RPC methods that are defined in the specification take a context and a params pointer as arguments, and return a result pointer and error:

```go
func (*ClientSession) ListTools(context.Context, *ListToolsParams) (*ListToolsResult, error)
```

Our SDK has a method for every RPC in the spec, their signatures all share this form. We do this, rather than providing more convenient shortcut signatures, to maintain backward compatibility if the spec makes backward-compatible changes such as adding a new property to the request parameters (as in [this commit](https://github.com/modelcontextprotocol/modelcontextprotocol/commit/2fce8a077688bf8011e80af06348b8fe1dae08ac), for example). To avoid boilerplate, we don't repeat this signature for RPCs defined in the spec; readers may assume it when we mention a "spec method."

`CallTool` is the only exception: for convenience when binding to Go argument types, `*CallToolParams[TArgs]` is generic, with a type parameter providing the Go type of the tool arguments. The spec method accepts a `*CallToolParams[json.RawMessage]`, but we provide a generic helper function. See the section on Tools below for details.

Why do we use params instead of the full JSON-RPC request? As much as possible, we endeavor to hide JSON-RPC details when they are not relevant to the business logic of your client or server. In this case, the additional information in the JSON-RPC request is just the request ID and method name; the request ID is irrelevant, and the method name is implied by the name of the Go method providing the API.

We believe that any change to the spec that would require callers to pass a new a parameter is not backward compatible. Therefore, it will always work to pass `nil` for any `XXXParams` argument that isn't currently necessary. For example, it is okay to call `Ping` like so:

```go
err := session.Ping(ctx, nil)
```

#### Iterator Methods

For convenience, iterator methods handle pagination for the `List` spec methods automatically, traversing all pages. If Params are supplied, iteration begins from the provided cursor (if present).

```go
func (*ClientSession) Tools(context.Context, *ListToolsParams) iter.Seq2[Tool, error]

func (*ClientSession) Prompts(context.Context, *ListPromptsParams) iter.Seq2[Prompt, error]

func (*ClientSession) Resources(context.Context, *ListResourceParams) iter.Seq2[Resource, error]

func (*ClientSession) ResourceTemplates(context.Context, *ListResourceTemplatesParams) iter.Seq2[ResourceTemplate, error]
```

### Middleware

We provide a mechanism to add MCP-level middleware on the both the client and server side. Receiving middleware runs after the request has been parsed but before any normal handling. It is analogous to traditional HTTP server middleware. Sending middleware runs after a call to a method but before the request is sent. It is an alternative to transport middleware that exposes MCP types instead of raw JSON-RPC 2.0 messages. It is useful for tracing and setting progress tokens, for example.

```go
// A MethodHandler handles MCP messages.
// The params argument is an XXXParams struct pointer, such as *GetPromptParams.
// For methods, a MethodHandler must return either an XXResult struct pointer and a nil error, or
// nil with a non-nil error.
// For notifications, a MethodHandler must return nil, nil.
type MethodHandler[S Session] func(
	ctx context.Context, _ *S, method string, params Params) (result Result, err error)

// Middleware is a function from MethodHandlers to MethodHandlers.
type Middleware[S Session] func(MethodHandler[S]) MethodHandler[S]

// AddMiddleware wraps the client/server's current method handler using the provided
// middleware. Middleware is applied from right to left, so that the first one
// is executed first.
//
// For example, AddMiddleware(m1, m2, m3) augments the server method handler as
// m1(m2(m3(handler))).
func (c *Client) AddSendingMiddleware(middleware ...Middleware[*ClientSession])
func (c *Client) AddReceivingMiddleware(middleware ...Middleware[*ClientSession])
func (s *Server) AddSendingMiddleware(middleware ...Middleware[*ServerSession])
func (s *Server) AddReceivingMiddleware(middleware ...Middleware[*ServerSession])
```

As an example, this code adds server-side logging:

```go
func withLogging(h mcp.MethodHandler[*ServerSession]) mcp.MethodHandler[*ServerSession]{
    return func(ctx context.Context, s *mcp.ServerSession, method string, params any) (res any, err error) {
        log.Printf("request: %s %v", method, params)
        defer func() { log.Printf("response: %v, %v", res, err) }()
        return h(ctx, s , method, params)
    }
}

server.AddReceivingMiddleware(withLogging)
```

**Differences from mcp-go**: Version 0.26.0 of mcp-go defines 24 server hooks. Each hook consists of a field in the `Hooks` struct, a `Hooks.Add` method, and a type for the hook function. These are rarely used. The most common is `OnError`, which occurs fewer than ten times in open-source code.

### Errors

With the exception of tool handler errors, protocol errors are handled transparently as Go errors: errors in server-side feature handlers are propagated as errors from calls from the `ClientSession`, and vice-versa.

Protocol errors wrap a `JSONRPCError` type which exposes its underlying error code.

```go
type JSONRPCError struct {
	Code    int64           `json:"code"`
	Message string          `json:"message"`
	Data    json.RawMessage `json:"data,omitempty"`
}
```

As described by the [spec](https://modelcontextprotocol.io/specification/2025-03-26/server/tools#error-handling), tool execution errors are reported in tool results.

**Differences from mcp-go**: the `JSONRPCError` type here does not include ID and Method, which can be inferred from the caller. Otherwise, this behavior is similar.

### Cancellation

Cancellation is implemented transparently using context cancellation. The user can cancel an operation by cancelling the associated context:

```go
ctx, cancel := context.WithCancel(ctx)
go session.CallTool(ctx, "slow", map[string]any{}, nil)
cancel()
```

When this client call is cancelled, a `"notifications/cancelled"` notification is sent to the server. However, the client call returns immediately with `ctx.Err()`: it does not wait for the result from the server.

The server observes a client cancellation as a cancelled context.

### Progress handling

A caller can request progress notifications by setting the `Meta.ProgressToken` field on any request.

```go
type XXXParams struct { // where XXX is each type of call
  Meta Meta
  ...
}

type Meta struct {
  Data          map[string]any
  ProgressToken any // string or int
}
```

Handlers can notify their peer about progress by calling the `NotifyProgress` method. The notification is only sent if the peer requested it by providing a progress token.

```go
func (*ClientSession) NotifyProgress(context.Context, *ProgressNotification)
func (*ServerSession) NotifyProgress(context.Context, *ProgressNotification)
```

### Ping / KeepAlive

Both `ClientSession` and `ServerSession` expose a `Ping` method to call "ping" on their peer.

```go
func (c *ClientSession) Ping(ctx context.Context, *PingParams) error
func (c *ServerSession) Ping(ctx context.Context, *PingParams) error
```

Additionally, client and server sessions can be configured with automatic keepalive behavior. If the `KeepAlive` option is set to a non-zero duration, it defines an interval for regular "ping" requests. If the peer fails to respond to pings originating from the keepalive check, the session is automatically closed.

```go
type ClientOptions struct {
  ...
  KeepAlive time.Duration
}

type ServerOptions struct {
  ...
  KeepAlive time.Duration
}
```

**Differences from mcp-go**: in mcp-go the `Ping` method is only provided for client, not server, and the keepalive option is only provided for SSE servers (as a variadic option).

## Client Features

### Roots

Clients support the MCP Roots feature, including roots-changed notifications. Roots can be added and removed from a `Client` with `AddRoots` and `RemoveRoots`:

```go
// AddRoots adds the given roots to the client,
// replacing any with the same URIs,
// and notifies any connected servers.
func (*Client) AddRoots(roots ...*Root)

// RemoveRoots removes the roots with the given URIs.
// and notifies any connected servers if the list has changed.
// It is not an error to remove a nonexistent root.
func (*Client) RemoveRoots(uris ...string)
```

Server sessions can call the spec method `ListRoots` to get the roots. If a server installs a `RootsChangedHandler`, it will be called when the client sends a roots-changed notification, which happens whenever the list of roots changes after a connection has been established.

```go
type ServerOptions {
  ...
  // If non-nil, called when a client sends a roots-changed notification.
  RootsChangedHandler func(context.Context, *ServerSession, *RootsChangedParams)
}
```

The `Roots` method provides a [cached](https://modelcontextprotocol.io/specification/2025-03-26/client/roots#implementation-guidelines) iterator of the root set, invalidated when roots change.

```go
func (*ServerSession) Roots(context.Context) (iter.Seq[*Root, error])
```

### Sampling

Clients that support sampling are created with a `CreateMessageHandler` option for handling server calls. To perform sampling, a server session calls the spec method `CreateMessage`.

```go
type ClientOptions struct {
  ...
  CreateMessageHandler func(context.Context, *ClientSession, *CreateMessageParams) (*CreateMessageResult, error)
}
```

## Server Features

### Tools

A `Tool` is a logical MCP tool, generated from the MCP spec, and a `ServerTool` is a tool bound to a tool handler.

A tool handler accepts `CallToolParams` and returns a `CallToolResult`. However, since we want to bind tools to Go input types, it is convenient in associated APIs to make `CallToolParams` generic, with a type parameter `TArgs` for the tool argument type. This allows tool APIs to manage the marshalling and unmarshalling of tool inputs for their caller. The bound `ServerTool` type expects a `json.RawMessage` for its tool arguments, but the `NewServerTool` constructor described below provides a mechanism to bind a typed handler.

```go
type CallToolParams[TArgs any] struct {
	Meta      Meta   `json:"_meta,omitempty"`
	Arguments TArgs  `json:"arguments,omitempty"`
	Name      string `json:"name"`
}

type Tool struct {
	Annotations *ToolAnnotations   `json:"annotations,omitempty"`
	Description string             `json:"description,omitempty"`
	InputSchema *jsonschema.Schema `json:"inputSchema"`
	Name string                    `json:"name"`
}

type ToolHandler[TArgs] func(context.Context, *ServerSession, *CallToolParams[TArgs]) (*CallToolResult, error)

type ServerTool struct {
	Tool    Tool
	Handler ToolHandler[json.RawMessage]
}
```

Add tools to a server with `AddTools`:

```go
server.AddTools(
  mcp.NewServerTool("add", "add numbers", addHandler),
  mcp.NewServerTool("subtract, subtract numbers", subHandler))
```

Remove them by name with `RemoveTools`:

```go
server.RemoveTools("add", "subtract")
```

A tool's input schema, expressed as a [JSON Schema](https://json-schema.org), provides a way to validate the tool's input. One of the challenges in defining tools is the need to associate them with a Go function, yet support the arbitrary complexity of JSON Schema. To achieve this, we have seen two primary approaches:

1. Use reflection to generate the tool's input schema from a Go type (à la `metoro-io/mcp-golang`)
2. Explicitly build the input schema (à la `mark3labs/mcp-go`).

Both of these have their advantages and disadvantages. Reflection is nice, because it allows you to bind directly to a Go API, and means that the JSON schema of your API is compatible with your Go types by construction. It also means that concerns like parsing and validation can be handled automatically. However, it can become cumbersome to express the full breadth of JSON schema using Go types or struct tags, and sometimes you want to express things that aren’t naturally modeled by Go types, like unions. Explicit schemas are simple and readable, and give the caller full control over their tool definition, but involve significant boilerplate.

We have found that a hybrid model works well, where the _initial_ schema is derived using reflection, but any customization on top of that schema is applied using variadic options. We achieve this using a `NewServerTool` helper, which generates the schema from the input type, and wraps the handler to provide parsing and validation. The schema (and potentially other features) can be customized using ToolOptions.

```go
// NewServerTool creates a Tool using reflection on the given handler.
func NewServerTool[TArgs any](name, description string, handler ToolHandler[TArgs], opts …ToolOption) *ServerTool

type ToolOption interface { /* ... */ }
```

`NewServerTool` determines the input schema for a Tool from the `TArgs` type. Each struct field that would be marshaled by `encoding/json.Marshal` becomes a property of the schema. The property is required unless the field's `json` tag specifies "omitempty" or "omitzero" (new in Go 1.24). For example, given this struct:

```go
struct {
  Name     string `json:"name"`
  Count    int    `json:"count,omitempty"`
  Choices  []string
  Password []byte `json:"-"`
}
```

"name" and "Choices" are required, while "count" is optional.

As of this writing, the only `ToolOption` is `Input`, which allows customizing the input schema of the tool using schema options. These schema options are recursive, in the sense that they may also be applied to properties.

```go
func Input(...SchemaOption) ToolOption

type Property(name string, opts ...SchemaOption) SchemaOption
type Description(desc string) SchemaOption
// etc.
```

For example:

```go
NewServerTool(name, description, handler,
    Input(Property("count", Description("size of the inventory"))))
```

The most recent JSON Schema spec defines over 40 keywords. Providing them all as options would bloat the API despite the fact that most would be very rarely used. For less common keywords, use the `Schema` option to set the schema explicitly:

```go
NewServerTool(name, description, handler,
    Input(Property("Choices", Schema(&jsonschema.Schema{UniqueItems: true}))))
```

Schemas are validated on the server before the tool handler is called.

Since all the fields of the Tool struct are exported, a Tool can also be created directly with assignment or a struct literal.

Client sessions can call the spec method `ListTools` or an iterator method `Tools` to list the available tools, and use spec method `CallTool` to call tools. Similar to `ServerTool.Handler`, `CallTool` expects `*CallToolParams[json.RawMessage]`, but we provide a generic `CallTool` helper to operate on typed arguments.

```go
func (cs *ClientSession) CallTool(context.Context, *CallToolParams[json.RawMessage]) (*CallToolResult, error)

func CallTool[TArgs any](context.Context, *ClientSession, *CallToolParams[TArgs]) (*CallToolResult, error)
```

**Differences from mcp-go**: using variadic options to configure tools was significantly inspired by mcp-go. However, the distinction between `ToolOption` and `SchemaOption` allows for recursive application of schema options. For example, that limitation is visible in [this code](https://github.com/DCjanus/dida365-mcp-server/blob/master/cmd/mcp/tools.go#L315), which must resort to untyped maps to express a nested schema.

Additionally, the `NewServerTool` helper provides a means for building a tool from a Go function using reflection, that automatically handles parsing and validation of inputs.

We provide a full JSON Schema implementation for validating tool input schemas against incoming arguments. The `jsonschema.Schema` type provides exported features for all keywords in the JSON Schema draft2020-12 spec. Tool definers can use it to construct any schema they want, so there is no need to provide options for all of them. When combined with schema inference from input structs, we found that we needed only three options to cover the common cases, instead of mcp-go's 23. For example, we will provide `Enum`, which occurs 125 times in open source code, but not MinItems, MinLength or MinProperties, which each occur only once (and in an SDK that wraps mcp-go).

For registering tools, we provide only `AddTools`; mcp-go's `SetTools`, `AddTool`, `AddSessionTool`, and `AddSessionTools` are deemed unnecessary. (Similarly for Delete/Remove).

### Prompts

Use `NewServerPrompt` to create a prompt. As with tools, prompt argument schemas can be inferred from a struct, or obtained from options.

```go
func NewServerPrompt[TReq any](name, description string,
  handler func(context.Context, *ServerSession, TReq) (*GetPromptResult, error),
  opts ...PromptOption) *ServerPrompt
```

Use `AddPrompts` to add prompts to the server, and `RemovePrompts`
to remove them by name.

```go
type codeReviewArgs struct {
  Code string `json:"code"`
}

func codeReviewHandler(context.Context, *ServerSession, codeReviewArgs) {...}

server.AddPrompts(
  NewServerPrompt("code_review", "review code", codeReviewHandler,
    Argument("code", Description("the code to review"))))

server.RemovePrompts("code_review")
```

Client sessions can call the spec method `ListPrompts` or the iterator method `Prompts` to list the available prompts, and the spec method `GetPrompt` to get one.

**Differences from mcp-go**: We provide a `NewServerPrompt` helper to bind a prompt handler to a Go function using reflection to derive its arguments. We provide `RemovePrompts` to remove prompts from the server.

### Resources and resource templates

In our design, each resource and resource template is associated with a function that reads it, with this signature:

```go
type ResourceHandler func(context.Context, *ServerSession, *ReadResourceParams) (*ReadResourceResult, error)
```

The arguments include the `ServerSession` so the handler can observe the client's roots. The handler should return the resource contents in a `ReadResourceResult`, calling either `NewTextResourceContents` or `NewBlobResourceContents`. If the handler omits the URI or MIME type, the server will populate them from the resource.

The `ServerResource` and `ServerResourceTemplate` types hold the association between the resource and its handler:

```go
type ServerResource struct {
  Resource Resource
  Handler  ResourceHandler
}

type ServerResourceTemplate struct {
  Template ResourceTemplate
  Handler  ResourceHandler
}
```

To add a resource or resource template to a server, users call the `AddResources` and `AddResourceTemplates` methods with one or more `ServerResource`s or `ServerResourceTemplate`s. We also provide methods to remove them.

```go
func (*Server) AddResources(...*ServerResource)
func (*Server) AddResourceTemplates(...*ServerResourceTemplate)

func (s *Server) RemoveResources(uris ...string)
func (s *Server) RemoveResourceTemplates(uriTemplates ...string)
```

The `ReadResource` method finds a resource or resource template matching the argument URI and calls its associated handler.

To read files from the local filesystem, we recommend using `FileResourceHandler` to construct a handler:

```go
// FileResourceHandler returns a ResourceHandler that reads paths using dir as a root directory.
// It protects against path traversal attacks.
// It will not read any file that is not in the root set of the client requesting the resource.
func (*Server) FileResourceHandler(dir string) ResourceHandler
```

Here is an example:

```go
// Safely read "/public/puppies.txt".
s.AddResources(&mcp.ServerResource{
  Resource: mcp.Resource{URI: "file:///puppies.txt"},
  Handler: s.FileReadResourceHandler("/public")})
```

Server sessions also support the spec methods `ListResources` and `ListResourceTemplates`, and the corresponding iterator methods `Resources` and `ResourceTemplates`.

**Differences from mcp-go**: for symmetry with tools and prompts, we use `AddResources` rather than `AddResource`. Additionally, the `ResourceHandler` returns a `ReadResourceResult`, rather than just its content, for compatibility with future evolution of the spec.

#### Subscriptions

ClientSessions can manage change notifications on particular resources:

```go
func (*ClientSession) Subscribe(context.Context, *SubscribeParams) error
func (*ClientSession) Unsubscribe(context.Context, *UnsubscribeParams) error
```

The server does not implement resource subscriptions. It passes along subscription requests to the user, and supplies a method to notify clients of changes. It tracks which sessions have subscribed to which resources so the user doesn't have to.

If a server author wants to support resource subscriptions, they must provide handlers to be called when clients subscribe and unsubscribe. It is an error to provide only one of these handlers.

```go
type ServerOptions struct {
  ...
  // Function called when a client session subscribes to a resource.
  SubscribeHandler func(context.Context, *SubscribeParams) error
  // Function called when a client session unsubscribes from a resource.
  UnsubscribeHandler func(context.Context, *UnsubscribeParams) error
}
```

User code should call `ResourceUpdated` when a subscribed resource changes.

```go
func (*Server) ResourceUpdated(context.Context, *ResourceUpdatedNotification) error
```

The server routes these notifications to the server sessions that subscribed to the resource.

### ListChanged notifications

When a list of tools, prompts or resources changes as the result of an AddXXX or RemoveXXX call, the server informs all its connected clients by sending the corresponding type of notification. A client will receive these notifications if it was created with the corresponding option:

```go
type ClientOptions struct {
  ...
  ToolListChangedHandler func(context.Context, *ClientSession, *ToolListChangedParams)
  PromptListChangedHandler func(context.Context, *ClientSession, *PromptListChangedParams)
  // For both resources and resource templates.
  ResourceListChangedHandler func(context.Context, *ClientSession, *ResourceListChangedParams)
}
```

**Differences from mcp-go**: mcp-go instead provides a general `OnNotification` handler. For type-safety, and to hide JSON RPC details, we provide feature-specific handlers here.

### Completion

Clients call the spec method `Complete` to request completions. Servers automatically handle these requests based on their collections of prompts and resources.

**Differences from mcp-go**: the client API is similar. mcp-go has not yet defined its server-side behavior.

### Logging

MCP specifies a notification for servers to log to clients. Server sessions implement this with the `LoggingMessage` method. It honors the minimum log level established by the client session's `SetLevel` call.

As a convenience, we also provide a `slog.Handler` that allows server authors to write logs with the `log/slog` package::

```go
// A LoggingHandler is a [slog.Handler] for MCP.
type LoggingHandler struct {...}

// LoggingHandlerOptions are options for a LoggingHandler.
type LoggingHandlerOptions struct {
	// The value for the "logger" field of logging notifications.
	LoggerName string
	// Limits the rate at which log messages are sent.
	// If zero, there is no rate limiting.
	MinInterval time.Duration
}

// NewLoggingHandler creates a [LoggingHandler] that logs to the given [ServerSession] using a
// [slog.JSONHandler].
func NewLoggingHandler(ss *ServerSession, opts *LoggingHandlerOptions) *LoggingHandler
```

Server-to-client logging is configured with `ServerOptions`:

```go
type ServerOptions {
  ...
  // The value for the "logger" field of the notification.
  LoggerName string
  // Log notifications to a single ClientSession will not be
  // sent more frequently than this duration.
  LoggingInterval time.Duration
}
```

A call to a log method like `Info` is translated to a `LoggingMessageNotification` as follows:

- The attributes and the message populate the "data" property with the output of a `slog.JSONHandler`: The result is always a JSON object, with the key "msg" for the message.

- If the `LoggerName` server option is set, it populates the "logger" property.

- The standard slog levels `Info`, `Debug`, `Warn` and `Error` map to the corresponding levels in the MCP spec. The other spec levels map to integers between the slog levels. For example, "notice" is level 2 because it is between "warning" (slog value 4) and "info" (slog value 0). The `mcp` package defines consts for these levels. To log at the "notice" level, a handler would call `Log(ctx, mcp.LevelNotice, "message")`.

A client that wishes to receive log messages must provide a handler:

```go
type ClientOptions struct {
  ...
  LoggingMessageHandler func(context.Context, *ClientSession, *LoggingMessageParams)
}
```

### Pagination

Servers initiate pagination for `ListTools`, `ListPrompts`, `ListResources`, and `ListResourceTemplates`, dictating the page size and providing a `NextCursor` field in the Result if more pages exist. The SDK implements keyset pagination, using the unique ID of the feature as the key for a stable sort order and encoding the cursor as an opaque string.

For server implementations, the page size for the list operation may be configured via the `ServerOptions.PageSize` field. PageSize must be a non-negative integer. If zero, a sensible default is used.

```go
type ServerOptions {
  ...
  PageSize int
}
```

Client requests for List methods include an optional Cursor field for pagination. Server responses for List methods include a `NextCursor` field if more pages exist.

In addition to the `List` methods, the SDK provides an iterator method for each list operation. This simplifies pagination for clients by automatically handling the underlying pagination logic. See [Iterator Methods](#iterator-methods) above.

**Differences with mcp-go**: the PageSize configuration is set with a configuration field rather than a variadic option. Additionally, this design proposes pagination by default, as this is likely desirable for most servers

# Governance and Community

While the sections above propose an initial implementation of the Go SDK, MCP is evolving rapidly. SDKs need to keep pace, by implementing changes to the spec, fixing bugs, and accommodating new and emerging use-cases. This section proposes how the SDK project can be managed so that it can change safely and transparently.

Initially, the Go SDK repository will be administered by the Go team and Anthropic, and they will be the Approvers (the set of people able to merge PRs to the SDK). The policies here are also intended to satisfy necessary constraints of the Go team's participation in the project.

The content in this section will also be included in a CONTRIBUTING.md file in the repo root.

## Hosting, copyright, and license

The SDK will be hosted under github.com/modelcontextprotocol/go-sdk, MIT license, copyright "Go SDK Authors". Each Go file in the repository will have a standard copyright header. For example:

```go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
```

## Issues and Contributing

The SDK will use its GitHub issue tracker for bug tracking, and pull requests for contributions.

Contributions to the SDK will be welcomed, and will be accepted provided they are high quality and consistent with the direction and philosophy of the SDK outlined above. An official SDK must be conservative in the changes it accepts, to defend against compatibility problems, security vulnerabilities, and churn. To avoid being declined, PRs should be associated with open issues, and those issues should either be labeled 'Help Wanted', or the PR author should ask on the issue before contributing.

### Proposals

A proposal is an issue that proposes a new API for the SDK, or a change to the signature or behavior of an existing API. Proposals will be labeled with the 'Proposal' label, and require an explicit approval before being accepted (applied through the 'Proposal-Accepted' label). Proposals will remain open for at least a week to allow discussion before being accepted or declined by an Approver.

Proposals that are straightforward and uncontroversial may be approved based on GitHub discussion. However, proposals that are deemed to be sufficiently unclear or complicated will be deferred to a regular steering meeting (see below).

This process is similar to the [Go proposal process](https://github.com/golang/proposal), but is necessarily lighter weight to accommodate the greater rate of change expected for the SDK.

### Steering meetings

On a regular basis, we will host a virtual steering meeting to discuss outstanding proposals and other changes to the SDK. These 1hr meetings and their agenda will be announced in advance, and open to all to join. The meetings will be recorded, and recordings and meeting notes will be made available afterward.

This process is similar to the [Go Tools call](https://go.dev/wiki/golang-tools), though it is expected that meetings will at least initially occur on a more frequent basis (likely biweekly).

### Discord

Discord (either the public or private Anthropic discord servers) should only be used for logistical coordination or answering questions. Design discussion and decisions should occur in GitHub issues or public steering meetings.

### Antitrust considerations

It is important that the SDK avoids bias toward specific integration paths or providers. Therefore, the CONTRIBUTING.md file will include an antitrust policy that outlines terms and practices intended to avoid such bias, or the appearance thereof. (The details of this policy will be determined by Google and Anthropic lawyers).

## Releases and Versioning

The SDK will consist of a single Go module, and will be released through versioned Git tags. Accordingly, it will follow semantic versioning.

Up until the v1.0.0 release, the SDK may be unstable and may change in breaking ways. An initial v1.0.0 release will occur when the SDK is deemed by Approvers to be stable, production ready, and sufficiently complete (though some unimplemented features may remain). Subsequent to that release, new APIs will be added in minor versions, and breaking changes will require a v2 release of the module (and therefore should be avoided). All releases will have corresponding release notes in GitHub.

It is desirable that releases occur frequently, and that a v1.0.0 release is achieved as quickly as possible.

If feasible, the SDK will support all versions of the MCP spec. However, if breaking changes to the spec make this infeasible, preference will be given to the most recent version of the MCP spec.

## Ongoing evaluation

On an ongoing basis, the administrators of the SDK will evaluate whether it is keeping pace with changes to the MCP spec and meeting its goals of openness and transparency. If it is not meeting these goals, either because it exceeds the bandwidth of its current Approvers, or because the processes here are inadequate, these processes will be re-evaluated. At this time, the Approvers set may be expanded to include additional community members, based on their history of strong contribution.


================================================
FILE: internal/mcp/example_progress_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"sync/atomic"

	"golang.org/x/tools/internal/mcp"
)

var nextProgressToken atomic.Int64

// This middleware function adds a progress token to every outgoing request
// from the client.
func Example_progressMiddleware() {
	c := mcp.NewClient("test", "v1", nil)
	c.AddSendingMiddleware(addProgressToken[*mcp.ClientSession])
	_ = c
}

func addProgressToken[S mcp.Session](h mcp.MethodHandler[S]) mcp.MethodHandler[S] {
	return func(ctx context.Context, s S, method string, params mcp.Params) (result mcp.Result, err error) {
		params.GetMeta().ProgressToken = nextProgressToken.Add(1)
		return h(ctx, s, method, params)
	}
}


================================================
FILE: internal/mcp/examples/hello/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"net/url"
	"os"

	"golang.org/x/tools/internal/mcp"
)

var httpAddr = flag.String("http", "", "if set, use streamable HTTP at this address, instead of stdin/stdout")

type HiArgs struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.CallToolParamsFor[HiArgs]) (*mcp.CallToolResultFor[struct{}], error) {
	return &mcp.CallToolResultFor[struct{}]{
		Content: []*mcp.Content{
			mcp.NewTextContent("Hi " + params.Name),
		},
	}, nil
}

// TODO(jba): it should be OK for args to be a pointer, but this fails in
// jsonschema. Needs investigation.
func PromptHi(ctx context.Context, ss *mcp.ServerSession, params *mcp.GetPromptParams) (*mcp.GetPromptResult, error) {
	return &mcp.GetPromptResult{
		Description: "Code review prompt",
		Messages: []*mcp.PromptMessage{
			{Role: "user", Content: mcp.NewTextContent("Say hi to " + params.Arguments["name"])},
		},
	}, nil
}

func main() {
	flag.Parse()

	server := mcp.NewServer("greeter", "v0.0.1", nil)
	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi, mcp.Input(
		mcp.Property("name", mcp.Description("the name to say hi to")),
	)))
	server.AddPrompts(&mcp.ServerPrompt{
		Prompt:  &mcp.Prompt{Name: "greet"},
		Handler: PromptHi,
	})
	server.AddResources(&mcp.ServerResource{
		Resource: &mcp.Resource{
			Name:     "info",
			MIMEType: "text/plain",
			URI:      "embedded:info",
		},
		Handler: handleEmbeddedResource,
	})

	if *httpAddr != "" {
		handler := mcp.NewStreamableHTTPHandler(func(*http.Request) *mcp.Server {
			return server
		}, nil)
		log.Printf("MCP handler listening at %s", *httpAddr)
		http.ListenAndServe(*httpAddr, handler)
	} else {
		t := mcp.NewLoggingTransport(mcp.NewStdioTransport(), os.Stderr)
		if err := server.Run(context.Background(), t); err != nil {
			log.Printf("Server failed: %v", err)
		}
	}
}

var embeddedResources = map[string]string{
	"info": "This is the hello example server.",
}

func handleEmbeddedResource(_ context.Context, _ *mcp.ServerSession, params *mcp.ReadResourceParams) (*mcp.ReadResourceResult, error) {
	u, err := url.Parse(params.URI)
	if err != nil {
		return nil, err
	}
	if u.Scheme != "embedded" {
		return nil, fmt.Errorf("wrong scheme: %q", u.Scheme)
	}
	key := u.Opaque
	text, ok := embeddedResources[key]
	if !ok {
		return nil, fmt.Errorf("no embedded resource named %q", key)
	}
	return &mcp.ReadResourceResult{
		Contents: []*mcp.ResourceContents{mcp.NewTextResourceContents(params.URI, "text/plain", text)},
	}, nil
}


================================================
FILE: internal/mcp/examples/sse/main.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package main

import (
	"context"
	"flag"
	"log"
	"net/http"

	"golang.org/x/tools/internal/mcp"
)

var httpAddr = flag.String("http", "", "use SSE HTTP at this address")

type SayHiParams struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, cc *mcp.ServerSession, params *mcp.CallToolParamsFor[SayHiParams]) (*mcp.CallToolResultFor[any], error) {
	return &mcp.CallToolResultFor[any]{
		Content: []*mcp.Content{
			mcp.NewTextContent("Hi " + params.Name),
		},
	}, nil
}

func main() {
	flag.Parse()

	if httpAddr == nil || *httpAddr == "" {
		log.Fatal("http address not set")
	}

	server1 := mcp.NewServer("greeter1", "v0.0.1", nil)
	server1.AddTools(mcp.NewServerTool("greet1", "say hi", SayHi))

	server2 := mcp.NewServer("greeter2", "v0.0.1", nil)
	server2.AddTools(mcp.NewServerTool("greet2", "say hello", SayHi))

	log.Printf("MCP servers serving at %s\n", *httpAddr)
	handler := mcp.NewSSEHandler(func(request *http.Request) *mcp.Server {
		url := request.URL.Path
		log.Printf("Handling request for URL %s\n", url)
		switch url {
		case "/greeter1":
			return server1
		case "/greeter2":
			return server2
		default:
			return nil
		}
	})
	http.ListenAndServe(*httpAddr, handler)
}


================================================
FILE: internal/mcp/features.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"iter"
	"maps"
	"slices"
)

// This file contains implementations that are common to all features.
// A feature is an item provided to a peer. In the 2025-03-26 spec,
// the features are prompt, tool, resource and root.

// A featureSet is a collection of features of type T.
// Every feature has a unique ID, and the spec never mentions
// an ordering for the List calls, so what it calls a "list" is actually a set.
// TODO: switch to an ordered map
type featureSet[T any] struct {
	uniqueID   func(T) string
	features   map[string]T
	sortedKeys []string // lazily computed; nil after add or remove
}

// newFeatureSet creates a new featureSet for features of type T.
// The argument function should return the unique ID for a single feature.
func newFeatureSet[T any](uniqueIDFunc func(T) string) *featureSet[T] {
	return &featureSet[T]{
		uniqueID: uniqueIDFunc,
		features: make(map[string]T),
	}
}

// add adds each feature to the set if it is not present,
// or replaces an existing feature.
func (s *featureSet[T]) add(fs ...T) {
	for _, f := range fs {
		s.features[s.uniqueID(f)] = f
	}
	s.sortedKeys = nil
}

// remove removes all features with the given uids from the set if present,
// and returns whether any were removed.
// It is not an error to remove a nonexistent feature.
func (s *featureSet[T]) remove(uids ...string) bool {
	changed := false
	for _, uid := range uids {
		if _, ok := s.features[uid]; ok {
			changed = true
			delete(s.features, uid)
		}
	}
	if changed {
		s.sortedKeys = nil
	}
	return changed
}

// get returns the feature with the given uid.
// If there is none, it returns zero, false.
func (s *featureSet[T]) get(uid string) (T, bool) {
	t, ok := s.features[uid]
	return t, ok
}

// all returns an iterator over of all the features in the set
// sorted by unique ID.
func (s *featureSet[T]) all() iter.Seq[T] {
	s.sortKeys()
	return func(yield func(T) bool) {
		s.yieldFrom(0, yield)
	}
}

// above returns an iterator over features in the set whose unique IDs are
// greater than `uid`, in ascending ID order.
func (s *featureSet[T]) above(uid string) iter.Seq[T] {
	s.sortKeys()
	index, found := slices.BinarySearch(s.sortedKeys, uid)
	if found {
		index++
	}
	return func(yield func(T) bool) {
		s.yieldFrom(index, yield)
	}
}

// sortKeys is a helper that maintains a sorted list of feature IDs. It
// computes this list lazily upon its first call after a modification, or
// if it's nil.
func (s *featureSet[T]) sortKeys() {
	if s.sortedKeys != nil {
		return
	}
	s.sortedKeys = slices.Sorted(maps.Keys(s.features))
}

// yieldFrom is a helper that iterates over the features in the set,
// starting at the given index, and calls the yield function for each one.
func (s *featureSet[T]) yieldFrom(index int, yield func(T) bool) {
	for i := index; i < len(s.sortedKeys); i++ {
		if !yield(s.features[s.sortedKeys[i]]) {
			return
		}
	}
}


================================================
FILE: internal/mcp/features_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"slices"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

type SayHiParams struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, cc *ServerSession, params *CallToolParamsFor[SayHiParams]) (*CallToolResultFor[any], error) {
	return &CallToolResultFor[any]{
		Content: []*Content{
			NewTextContent("Hi " + params.Name),
		},
	}, nil
}

func TestFeatureSetOrder(t *testing.T) {
	toolA := NewServerTool("apple", "apple tool", SayHi).Tool
	toolB := NewServerTool("banana", "banana tool", SayHi).Tool
	toolC := NewServerTool("cherry", "cherry tool", SayHi).Tool

	testCases := []struct {
		tools []*Tool
		want  []*Tool
	}{
		{[]*Tool{toolA, toolB, toolC}, []*Tool{toolA, toolB, toolC}},
		{[]*Tool{toolB, toolC, toolA}, []*Tool{toolA, toolB, toolC}},
		{[]*Tool{toolA, toolC}, []*Tool{toolA, toolC}},
		{[]*Tool{toolA, toolA, toolA}, []*Tool{toolA}},
		{[]*Tool{}, nil},
	}
	for _, tc := range testCases {
		fs := newFeatureSet(func(t *Tool) string { return t.Name })
		fs.add(tc.tools...)
		got := slices.Collect(fs.all())
		if diff := cmp.Diff(got, tc.want, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
			t.Errorf("expected %v, got %v, (-want +got):\n%s", tc.want, got, diff)
		}
	}
}

func TestFeatureSetAbove(t *testing.T) {
	toolA := NewServerTool("apple", "apple tool", SayHi).Tool
	toolB := NewServerTool("banana", "banana tool", SayHi).Tool
	toolC := NewServerTool("cherry", "cherry tool", SayHi).Tool

	testCases := []struct {
		tools []*Tool
		above string
		want  []*Tool
	}{
		{[]*Tool{toolA, toolB, toolC}, "apple", []*Tool{toolB, toolC}},
		{[]*Tool{toolA, toolB, toolC}, "banana", []*Tool{toolC}},
		{[]*Tool{toolA, toolB, toolC}, "cherry", nil},
	}
	for _, tc := range testCases {
		fs := newFeatureSet(func(t *Tool) string { return t.Name })
		fs.add(tc.tools...)
		got := slices.Collect(fs.above(tc.above))
		if diff := cmp.Diff(got, tc.want, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
			t.Errorf("expected %v, got %v, (-want +got):\n%s", tc.want, got, diff)
		}
	}
}


================================================
FILE: internal/mcp/generate.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// This script generates protocol definitions in protocol.go from the MCP spec.
//
// Only the set of declarations configured by the [declarations] value are
// generated.

package main

import (
	"bytes"
	"encoding/json"
	"flag"
	"fmt"
	"go/format"
	"io"
	"log"
	"maps"
	"net/http"
	"os"
	"reflect"
	"regexp"
	"slices"
	"strings"

	"golang.org/x/tools/internal/mcp/internal/util"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

var schemaFile = flag.String("schema_file", "", "if set, use this file as the persistent schema file")

// A typeConfig defines a rewrite to perform to a (possibly nested) struct
// field. In some cases, we may want to use an external type for the nested
// struct field. In others, we may want to extract the type definition to a
// name.
type typeConfig struct {
	Name       string      // declaration name for the type
	TypeParams [][2]string // formatted type parameter list ({name, constraint}), if any
	Substitute string      // type definition to substitute
	Fields     config      // individual field configuration, or nil
}

type config map[string]*typeConfig

// declarations configures the set of declarations to write.
//
// Top level declarations are created unless configured with Name=="-",
// in which case they are discarded, though their fields may be
// extracted to types if they have a nested field configuration.
// If Name == "", the map key is used as the type name.
var declarations = config{
	"Annotations": {},
	"CallToolRequest": {
		Name: "-",
		Fields: config{
			"Params": {
				Name: "CallToolParams",
				Fields: config{
					"Arguments": {Substitute: "any"},
				},
			},
		},
	},
	"CallToolResult": {},
	"CancelledNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "CancelledParams"}},
	},
	"ClientCapabilities": {
		Fields: config{"Sampling": {Name: "SamplingCapabilities"}},
	},
	"CreateMessageRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "CreateMessageParams"}},
	},
	"CreateMessageResult": {},
	"GetPromptRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "GetPromptParams"}},
	},
	"GetPromptResult": {},
	"Implementation":  {Name: "implementation"},
	"InitializeRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "InitializeParams"}},
	},
	"InitializeResult": {Name: "InitializeResult"},
	"InitializedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "InitializedParams"}},
	},
	"ListPromptsRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ListPromptsParams"}},
	},
	"ListPromptsResult": {},
	"ListResourcesRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ListResourcesParams"}},
	},
	"ListResourcesResult": {},
	"ListResourceTemplatesRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ListResourceTemplatesParams"}},
	},
	"ListResourceTemplatesResult": {},
	"ListRootsRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ListRootsParams"}},
	},
	"ListRootsResult": {},
	"ListToolsRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ListToolsParams"}},
	},
	"ListToolsResult":     {},
	"loggingCapabilities": {Substitute: "struct{}"},
	"LoggingLevel":        {},
	"LoggingMessageNotification": {
		Name: "-",
		Fields: config{
			"Params": {
				Name:   "LoggingMessageParams",
				Fields: config{"Data": {Substitute: "any"}},
			},
		},
	},
	"ModelHint":        {},
	"ModelPreferences": {},
	"PingRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "PingParams"}},
	},
	"Prompt":         {},
	"PromptMessage":  {},
	"PromptArgument": {},
	"PromptListChangedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "PromptListChangedParams"}},
	},
	"ProgressNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "ProgressNotificationParams"}},
	},
	"ProgressToken": {Name: "-", Substitute: "any"}, // null|number|string
	"RequestId":     {Name: "-", Substitute: "any"}, // null|number|string
	"ReadResourceRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "ReadResourceParams"}},
	},
	"ReadResourceResult": {
		Fields: config{"Contents": {Substitute: "[]*ResourceContents"}},
	},
	"Resource": {},
	"ResourceListChangedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "ResourceListChangedParams"}},
	},
	"ResourceTemplate": {},
	"ResourceTemplateListChangedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "ResourceTemplateListChangedParams"}},
	},
	"Role": {},
	"Root": {},
	"RootsListChangedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "RootsListChangedParams"}},
	},

	"SamplingCapabilities": {Substitute: "struct{}"},
	"SamplingMessage":      {},
	"ServerCapabilities": {
		Name: "serverCapabilities",
		Fields: config{
			"Prompts":   {Name: "promptCapabilities"},
			"Resources": {Name: "resourceCapabilities"},
			"Tools":     {Name: "toolCapabilities"},
			"Logging":   {Name: "loggingCapabilities"},
		},
	},
	"SetLevelRequest": {
		Name:   "-",
		Fields: config{"Params": {Name: "SetLevelParams"}},
	},
	"Tool": {
		Fields: config{"InputSchema": {Substitute: "*jsonschema.Schema"}},
	},
	"ToolAnnotations": {},
	"ToolListChangedNotification": {
		Name:   "-",
		Fields: config{"Params": {Name: "ToolListChangedParams"}},
	},
}

func main() {
	flag.Parse()

	// Load and unmarshal the schema.
	data, err := loadSchema(*schemaFile)
	if err != nil {
		log.Fatal(err)
	}
	schema := new(jsonschema.Schema)
	if err := json.Unmarshal(data, &schema); err != nil {
		log.Fatal(err)
	}
	// Resolve the schema so we have the referents of all the Refs.
	if _, err := schema.Resolve(nil); err != nil {
		log.Fatal(err)
	}

	// Collect named types. Since we may create new type definitions while
	// writing types, we collect definitions and concatenate them later. This
	// also allows us to sort.
	named := make(map[string]*bytes.Buffer)
	for name, def := range util.Sorted(schema.Definitions) {
		config := declarations[name]
		if config == nil {
			continue
		}
		if err := writeDecl(name, *config, def, named); err != nil {
			log.Fatal(err)
		}
	}

	buf := new(bytes.Buffer)
	fmt.Fprintf(buf, `
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package mcp

import (
	"golang.org/x/tools/internal/mcp/jsonschema"
)
`)

	// Write out types.
	for _, b := range util.Sorted(named) {
		fmt.Fprintln(buf)
		fmt.Fprint(buf, b.String())
	}
	// Write out method names.
	fmt.Fprintln(buf, `const (`)
	for _, name := range slices.Sorted(maps.Keys(schema.Definitions)) {
		prefix := "method"
		method, found := strings.CutSuffix(name, "Request")
		if !found {
			prefix = "notification"
			method, found = strings.CutSuffix(name, "Notification")
		}
		if found {
			if ms, ok := schema.Definitions[name].Properties["method"]; ok {
				if c := ms.Const; c != nil {
					fmt.Fprintf(buf, "%s%s = %q\n", prefix, method, *c)
				}
			}
		}
	}
	fmt.Fprintln(buf, `)`)

	formatted, err := format.Source(buf.Bytes())
	if err != nil {
		log.Println(buf.String())
		log.Fatalf("failed to format: %v", err)
	}
	if err := os.WriteFile("protocol.go", formatted, 0666); err != nil {
		log.Fatalf("failed to write protocol.go: %v", err)
	}
}

func loadSchema(schemaFile string) (data []byte, err error) {
	const schemaURL = "https://raw.githubusercontent.com/modelcontextprotocol/modelcontextprotocol/refs/heads/main/schema/2025-03-26/schema.json"

	if schemaFile != "" {
		data, err = os.ReadFile(schemaFile)
		if os.IsNotExist(err) {
			data = nil
		} else if err != nil {
			return nil, fmt.Errorf("reading schema file %q: %v", schemaFile, err)
		}
	}
	if data == nil {
		resp, err := http.Get(schemaURL)
		if err != nil {
			return nil, fmt.Errorf("downloading schema: %v", err)
		}
		defer resp.Body.Close()
		if resp.StatusCode != http.StatusOK {
			return nil, fmt.Errorf("downloading schema: %v", resp.Status)
		}
		data, err = io.ReadAll(resp.Body)
		if err != nil {
			return nil, fmt.Errorf("reading schema body: %v", err)
		}
		if schemaFile != "" {
			if err := os.WriteFile(schemaFile, data, 0666); err != nil {
				return nil, fmt.Errorf("persisting schema: %v", err)
			}
		}
	}
	return data, nil
}

// Suffixes of type names with a meta field.
var metaSuffixes = []string{"Params", "ParamsFor", "Result", "ResultFor"}

func writeDecl(configName string, config typeConfig, def *jsonschema.Schema, named map[string]*bytes.Buffer) error {
	var w io.Writer = io.Discard
	var typeName string
	if typeName = config.Name; typeName != "-" {
		if typeName == "" {
			typeName = configName
		}
		if _, ok := named[typeName]; ok {
			return nil
		}
		// The JSON schema does not accurately represent the source of truth, which is typescript.
		// Every Params and Result type should have a _meta property.
		// Also, those with a progress token will turn into a struct; we want the progress token to
		// be a map item. So replace all metas.
		for _, s := range metaSuffixes {
			if strings.HasSuffix(typeName, s) {
				def.Properties["_meta"] = metaSchema
				break
			}
		}
		buf := new(bytes.Buffer)
		w = buf
		named[typeName] = buf
		if def.Description != "" {
			fmt.Fprintf(buf, "%s\n", toComment(def.Description))
		}
		typeParams := new(strings.Builder)
		if len(config.TypeParams) > 0 {
			typeParams.WriteByte('[')
			for i, p := range config.TypeParams {
				if i > 0 {
					typeParams.WriteString(", ")
				}
				fmt.Fprintf(typeParams, "%s %s", p[0], p[1])
			}
			typeParams.WriteByte(']')
		}
		fmt.Fprintf(buf, "type %s%s ", typeName, typeParams)
	}
	if err := writeType(w, &config, def, named); err != nil {
		return err // Better error here?
	}
	fmt.Fprintf(w, "\n")

	// Any decl with a _meta field gets a GetMeta method.
	if _, ok := def.Properties["_meta"]; ok {
		targs := new(strings.Builder)
		if len(config.TypeParams) > 0 {
			targs.WriteByte('[')
			for i, p := range config.TypeParams {
				if i > 0 {
					targs.WriteString(", ")
				}
				fmt.Fprintf(targs, "%s", p[0])
			}
			targs.WriteByte(']')
		}
		fmt.Fprintf(w, "\nfunc (x *%s%s) GetMeta() *Meta { return &x.Meta }", typeName, targs)
	}

	if _, ok := def.Properties["cursor"]; ok {
		fmt.Fprintf(w, "\nfunc (x *%s) cursorPtr() *string { return &x.Cursor }", typeName)
	}
	if _, ok := def.Properties["nextCursor"]; ok {
		fmt.Fprintf(w, "\nfunc (x *%s) nextCursorPtr() *string { return &x.NextCursor }", typeName)
	}

	// Some types have generic counterparts.
	var typeArg, substField string
	switch typeName {
	case "CallToolParams":
		typeName = "CallToolParamsFor"
		typeArg = "In"
		substField = "Arguments"
	case "CallToolResult":
		typeName = "CallToolResultFor"
		typeArg = "Out"
		substField = "StructuredContent"
	}
	if typeArg != "" {
		fmt.Fprintf(w, "\n\ntype %s[%s any]", typeName, typeArg)
		if config.Fields != nil {
			config.Fields[substField].Substitute = typeArg
		}
		if err := writeType(w, &config, def, named); err != nil {
			return err
		}
		fmt.Fprintf(w, "\nfunc (x *%s[%s]) GetMeta() *Meta {return &x.Meta}", typeName, typeArg)
	}
	return nil
}

// writeType writes the type definition to the given writer.
//
// If path is non-empty, it is the path to the field using this type, for the
// purpose of detecting field rewrites (see [fieldRewrite]).
//
// named is the in-progress collection of type definitions. New named types may
// be added during writeType, if they are extracted from inner fields.
func writeType(w io.Writer, config *typeConfig, def *jsonschema.Schema, named map[string]*bytes.Buffer) error {
	// Use type names for Named types.
	name, resolved := deref(def)
	if name != "" {
		// TODO: this check is not quite right: we should really panic if the
		// definition is missing, *but only if w is not io.Discard*. That's not a
		// great API: see if we can do something more explicit than io.Discard.
		if cfg, ok := declarations[name]; ok {
			if cfg.Name == "-" && cfg.Substitute == "" {
				panic(fmt.Sprintf("referenced type %q cannot be referred to (no name or substitution)", name))
			}
			if cfg.Substitute != "" {
				name = cfg.Substitute
			} else if cfg.Name != "" {
				name = cfg.Name
			}
			if isStruct(resolved) {
				w.Write([]byte{'*'})
			}
		}
		w.Write([]byte(name))
		return nil
	}

	// For types that explicitly allow additional properties, we can either
	// unmarshal them into a map[string]any, or delay unmarshalling with
	// json.RawMessage. We use any.
	if def.Type == "object" && canHaveAdditionalProperties(def) && def.Properties == nil {
		w.Write([]byte("map[string]"))
		return writeType(w, nil, def.AdditionalProperties, named)
	}

	if def.Type == "" {
		// special case: recognize Content
		if slices.ContainsFunc(def.AnyOf, func(s *jsonschema.Schema) bool {
			return s.Ref == "#/definitions/TextContent"
		}) {
			fmt.Fprintf(w, "*Content")
		} else {
			// E.g. union types.
			fmt.Fprintf(w, "any")
		}
	} else {
		switch def.Type {
		case "array":
			fmt.Fprintf(w, "[]")
			return writeType(w, nil, def.Items, named)

		case "boolean":
			fmt.Fprintf(w, "bool")

		case "integer":
			fmt.Fprintf(w, "int64")

		// not handled: "null"

		case "number":
			// We could use json.Number here; use float64 for simplicity.
			fmt.Fprintf(w, "float64")

		case "object":
			fmt.Fprintf(w, "struct {\n")
			for name, fieldDef := range util.Sorted(def.Properties) {
				if fieldDef.Description != "" {
					fmt.Fprintf(w, "%s\n", toComment(fieldDef.Description))
				}
				if name == "_meta" {
					fmt.Fprintln(w, "\tMeta Meta `json:\"_meta,omitempty\"`")
					continue
				}

				export := exportName(name)
				fmt.Fprintf(w, "\t%s ", export)

				required := slices.Contains(def.Required, name)

				// If the field is a struct type, indirect with a
				// pointer so that it can be empty as defined by encoding/json.
				// This also future-proofs against the struct getting large.
				fieldTypeSchema := fieldDef
				// If the schema is a reference, dereference it.
				if _, rs := deref(fieldDef); rs != nil {
					fieldTypeSchema = rs
				}
				needPointer := isStruct(fieldTypeSchema)
				// Special case: there are no sampling or logging capabilities defined,
				// but we want them to be structs for future expansion.
				if !needPointer && (name == "sampling" || name == "logging") {
					needPointer = true
				}
				if config != nil && config.Fields[export] != nil {
					r := config.Fields[export]
					if r.Substitute != "" {
						fmt.Fprintf(w, r.Substitute)
					} else {
						assert(r.Name != "-", "missing ExtractTo")
						typename := export
						if r.Name != "" {
							typename = r.Name
						}
						if err := writeDecl(typename, *r, fieldDef, named); err != nil {
							return err
						}
						if needPointer {
							fmt.Fprintf(w, "*")
						}
						fmt.Fprintf(w, typename)
					}
				} else if err := writeType(w, nil, fieldDef, named); err != nil {
					return fmt.Errorf("failed to write type for field %s: %v", export, err)
				}
				fmt.Fprintf(w, " `json:\"%s", name)
				if !required {
					fmt.Fprint(w, ",omitempty")
				}
				fmt.Fprint(w, "\"`\n")
			}
			fmt.Fprintf(w, "}")

		case "string":
			fmt.Fprintf(w, "string")

		default:
			fmt.Fprintf(w, "any")
		}
	}
	return nil
}

// toComment converts a JSON schema description to a Go comment.
func toComment(description string) string {
	var (
		buf     strings.Builder
		lineBuf strings.Builder
	)
	const wrapAt = 80
	for line := range strings.SplitSeq(description, "\n") {
		// Start a new paragraph, if the current is nonempty.
		if len(line) == 0 && lineBuf.Len() > 0 {
			buf.WriteString(lineBuf.String())
			lineBuf.Reset()
			buf.WriteString("\n//\n")
			continue
		}
		// Otherwise, fill in the current paragraph.
		for field := range strings.FieldsSeq(line) {
			if lineBuf.Len() > 0 && lineBuf.Len()+len(" ")+len(field) > wrapAt {
				buf.WriteString(lineBuf.String())
				buf.WriteRune('\n')
				lineBuf.Reset()
			}
			if lineBuf.Len() == 0 {
				lineBuf.WriteString("//")
			}
			lineBuf.WriteString(" ")
			lineBuf.WriteString(field)
		}
	}
	if lineBuf.Len() > 0 {
		buf.WriteString(lineBuf.String())
	}
	return strings.TrimRight(buf.String(), "\n")
}

// The MCP spec improperly uses the absence of the additionalProperties keyword to
// mean that additional properties are not allowed. In fact, it means just the opposite
// (https://json-schema.org/draft-07/draft-handrews-json-schema-validation-01#rfc.section.6.5.6).
// If the MCP spec wants to allow additional properties, it will write "true" or
// an object explicitly.
func canHaveAdditionalProperties(s *jsonschema.Schema) bool {
	ap := s.AdditionalProperties
	return ap != nil && !reflect.DeepEqual(ap, &jsonschema.Schema{Not: &jsonschema.Schema{}})
}

// exportName returns an exported name for a Go symbol, based on the given name
// in the JSON schema, removing leading underscores and capitalizing.
// It also rewrites initialisms.
func exportName(s string) string {
	if strings.HasPrefix(s, "_") {
		s = s[1:]
	}
	s = strings.ToUpper(s[:1]) + s[1:]
	// Replace an initialism if it is its own "word": see the init function below for
	// a definition.
	// There is probably a clever way to write this whole thing with one regexp and
	// a Replace method, but it would be quite obscure.
	// This doesn't have to be fast, because the first match will rarely succeed.
	for ism, re := range initialisms {
		replacement := strings.ToUpper(ism)
		// Find the index of one match at a time, and replace. (We can't find all
		// at once, because the replacement will change the indices.)
		for {
			if loc := re.FindStringIndex(s); loc != nil {
				// Don't replace the rune after the initialism, if any.
				end := loc[1]
				if end < len(s) {
					end--
				}
				s = s[:loc[0]] + replacement + s[end:]
			} else {
				break
			}
		}
	}
	return s
}

// deref dereferences s.Ref.
// If s.Ref refers to a schema in the Definitions section, deref
// returns the definition name and the associated schema.
// Otherwise, deref returns "", nil.
func deref(s *jsonschema.Schema) (name string, _ *jsonschema.Schema) {
	name, ok := strings.CutPrefix(s.Ref, "#/definitions/")
	if !ok {
		return "", nil
	}
	return name, s.ResolvedRef()
}

// isStruct reports whether s should be translated to a struct.
func isStruct(s *jsonschema.Schema) bool {
	return s.Type == "object" && s.Properties != nil && !canHaveAdditionalProperties(s)
}

// The schema for "_meta".
// We only need the description: the rest is a special case.
var metaSchema = &jsonschema.Schema{
	Description: "This property is reserved by the protocol to allow clients and servers to attach additional metadata to their responses.",
}

// schemaJSON returns the JSON for s.
// For debugging.
func schemaJSON(s *jsonschema.Schema) string {
	data, err := json.Marshal(s)
	if err != nil {
		return fmt.Sprintf("<jsonschema.Schema:%v>", err)
	}
	return string(data)
}

// Map from initialism to the regexp that matches it.
var initialisms = map[string]*regexp.Regexp{
	"Id":   nil,
	"Url":  nil,
	"Uri":  nil,
	"Mime": nil,
}

func init() {
	for ism := range initialisms {
		// Match ism if it is at the end, or followed by an uppercase letter or a number.
		initialisms[ism] = regexp.MustCompile(ism + `($|[A-Z0-9])`)
	}
}

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}


================================================
FILE: internal/mcp/internal/oauthex/oauth2.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package oauthex implements extensions to OAuth2.
package oauthex


================================================
FILE: internal/mcp/internal/oauthex/oauth2_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package oauthex

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"reflect"
	"testing"
)

func TestSplitChallenges(t *testing.T) {
	tests := []struct {
		name  string
		input string
		want  []string
	}{
		{
			name:  "single challenge no params",
			input: `Basic`,
			want:  []string{`Basic`},
		},
		{
			name:  "single challenge with params",
			input: `Bearer realm="example.com", error="invalid_token"`,
			want:  []string{`Bearer realm="example.com", error="invalid_token"`},
		},
		{
			name:  "single challenge with comma in quoted string",
			input: `Bearer realm="example, with comma"`,
			want:  []string{`Bearer realm="example, with comma"`},
		},
		{
			name:  "two challenges",
			input: `Basic, Bearer realm="example"`,
			want:  []string{`Basic`, ` Bearer realm="example"`},
		},
		{
			name:  "multiple challenges complex",
			input: `Newauth realm="apps", Basic, Bearer realm="example.com", error="invalid_token"`,
			want:  []string{`Newauth realm="apps"`, ` Basic`, ` Bearer realm="example.com", error="invalid_token"`},
		},
		{
			name:  "challenge with escaped quote",
			input: `Bearer realm="example \"quoted\""`,
			want:  []string{`Bearer realm="example \"quoted\""`},
		},
		{
			name:  "empty input",
			input: "",
			want:  []string{""},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := splitChallenges(tt.input)
			if err != nil {
				t.Fatal(err)
			}
			if !reflect.DeepEqual(got, tt.want) {
				t.Errorf("splitChallenges() = %v, want %v", got, tt.want)
			}
		})
	}
}

func TestSplitChallengesError(t *testing.T) {
	if _, err := splitChallenges(`"Bearer"`); err == nil {
		t.Fatal("got nil, want error")
	}
}

func TestParseSingleChallenge(t *testing.T) {
	tests := []struct {
		name    string
		input   string
		want    challenge
		wantErr bool
	}{
		{
			name:  "scheme only",
			input: "Basic",
			want: challenge{
				Scheme: "basic",
			},
			wantErr: false,
		},
		{
			name:  "scheme with one quoted param",
			input: `Bearer realm="example.com"`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{"realm": "example.com"},
			},
			wantErr: false,
		},
		{
			name:  "scheme with one unquoted param",
			input: `Bearer realm=example.com`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{"realm": "example.com"},
			},
			wantErr: false,
		},
		{
			name:  "scheme with multiple params",
			input: `Bearer realm="example", error="invalid_token", error_description="The token expired"`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{
					"realm":             "example",
					"error":             "invalid_token",
					"error_description": "The token expired",
				},
			},
			wantErr: false,
		},
		{
			name:  "scheme with multiple unquoted params",
			input: `Bearer realm=example, error=invalid_token, error_description=The token expired`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{
					"realm":             "example",
					"error":             "invalid_token",
					"error_description": "The token expired",
				},
			},
			wantErr: false,
		},
		{
			name:  "case-insensitive scheme and keys",
			input: `BEARER ReAlM="example"`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{"realm": "example"},
			},
			wantErr: false,
		},
		{
			name:  "param with escaped quote",
			input: `Bearer realm="example \"foo\" bar"`,
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{"realm": `example "foo" bar`},
			},
			wantErr: false,
		},
		{
			name:  "param without quotes (token)",
			input: "Bearer realm=example.com",
			want: challenge{
				Scheme: "bearer",
				Params: map[string]string{"realm": "example.com"},
			},
			wantErr: false,
		},
		{
			name:    "malformed param - no value",
			input:   "Bearer realm=",
			wantErr: true,
		},
		{
			name:    "malformed param - unterminated quote",
			input:   `Bearer realm="example`,
			wantErr: true,
		},
		{
			name:    "malformed param - missing comma",
			input:   `Bearer realm="a" error="b"`,
			wantErr: true,
		},
		{
			name:    "malformed param - initial equal",
			input:   `Bearer ="a"`,
			wantErr: true,
		},
		{
			name:    "empty input",
			input:   "",
			wantErr: true,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			got, err := parseSingleChallenge(tt.input)
			if (err != nil) != tt.wantErr {
				t.Errorf("parseSingleChallenge() error = %v, wantErr %v", err, tt.wantErr)
				return
			}
			if !reflect.DeepEqual(got, tt.want) {
				t.Errorf("parseSingleChallenge() = %v, want %v", got, tt.want)
			}
		})
	}
}

func TestGetProtectedResourceMetadata(t *testing.T) {
	ctx := context.Background()
	t.Run("FromHeader", func(t *testing.T) {
		h := &fakeResourceHandler{serveWWWAuthenticate: true}
		server := httptest.NewTLSServer(h)
		h.installHandlers(server.URL)
		client := server.Client()
		res, err := client.Get(server.URL + "/resource")
		if err != nil {
			t.Fatal(err)
		}
		if res.StatusCode != http.StatusUnauthorized {
			t.Fatal("want unauth")
		}
		prm, err := GetProtectedResourceMetadataFromHeader(ctx, res.Header, client)
		if err != nil {
			t.Fatal(err)
		}
		if prm == nil {
			t.Fatal("nil prm")
		}
	})
	t.Run("FromID", func(t *testing.T) {
		h := &fakeResourceHandler{serveWWWAuthenticate: false}
		server := httptest.NewTLSServer(h)
		h.installHandlers(server.URL)
		client := server.Client()
		prm, err := GetProtectedResourceMetadataFromID(ctx, server.URL, client)
		if err != nil {
			t.Fatal(err)
		}
		if prm == nil {
			t.Fatal("nil prm")
		}
	})
}

type fakeResourceHandler struct {
	http.ServeMux
	serverURL            string
	serveWWWAuthenticate bool
}

func (h *fakeResourceHandler) installHandlers(serverURL string) {
	path := "/.well-known/oauth-protected-resource"
	url := serverURL + path
	h.Handle("GET /resource", http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if h.serveWWWAuthenticate {
			w.Header().Set("WWW-Authenticate", fmt.Sprintf(`Bearer resource_metadata="%s"`, url))
		}
		w.WriteHeader(http.StatusUnauthorized)
	}))
	h.Handle("GET "+path, http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "application/json")
		// If there is a WWW-Authenticate header, the resource field is the value of that header.
		// If not, it's the server URL without the "/.well-known/..." part.
		resource := serverURL
		if h.serveWWWAuthenticate {
			resource = url
		}
		prm := &ProtectedResourceMetadata{Resource: resource}
		if err := json.NewEncoder(w).Encode(prm); err != nil {
			panic(err)
		}
	}))
}


================================================
FILE: internal/mcp/internal/oauthex/resource_meta.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements Protected Resource Metadata.
// See https://www.rfc-editor.org/rfc/rfc9728.html.

package oauthex

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"net/http"
	"net/url"
	"path"
	"strings"
	"unicode"

	"golang.org/x/tools/internal/mcp/internal/util"
)

const defaultProtectedResourceMetadataURI = "/.well-known/oauth-protected-resource"

// ProtectedResourceMetadata is the metadata for an OAuth 2.0 protected resource,
// as defined in section 2 of https://www.rfc-editor.org/rfc/rfc9728.html.
//
// The following features are not supported:
// - additional keys (§2, last sentence)
// - human-readable metadata (§2.1)
// - signed metadata (§2.2)
type ProtectedResourceMetadata struct {
	// GENERATED BY GEMINI 2.5.

	// Resource (resource) is the protected resource's resource identifier.
	// Required.
	Resource string `json:"resource"`

	// AuthorizationServers (authorization_servers) is an optional slice containing a list of
	// OAuth authorization server issuer identifiers (as defined in RFC 8414) that can be
	// used with this protected resource.
	AuthorizationServers []string `json:"authorization_servers,omitempty"`

	// JWKSURI (jwks_uri) is an optional URL of the protected resource's JSON Web Key (JWK) Set
	// document. This contains public keys belonging to the protected resource, such as
	// signing key(s) that the resource server uses to sign resource responses.
	JWKSURI string `json:"jwks_uri,omitempty"`

	// ScopesSupported (scopes_supported) is a recommended slice containing a list of scope
	// values (as defined in RFC 6749) used in authorization requests to request access
	// to this protected resource.
	ScopesSupported []string `json:"scopes_supported,omitempty"`

	// BearerMethodsSupported (bearer_methods_supported) is an optional slice containing
	// a list of the supported methods of sending an OAuth 2.0 bearer token to the
	// protected resource. Defined values are "header", "body", and "query".
	BearerMethodsSupported []string `json:"bearer_methods_supported,omitempty"`

	// ResourceSigningAlgValuesSupported (resource_signing_alg_values_supported) is an optional
	// slice of JWS signing algorithms (alg values) supported by the protected
	// resource for signing resource responses.
	ResourceSigningAlgValuesSupported []string `json:"resource_signing_alg_values_supported,omitempty"`

	// ResourceName (resource_name) is a human-readable name of the protected resource
	// intended for display to the end user. It is RECOMMENDED that this field be included.
	// This value may be internationalized.
	ResourceName string `json:"resource_name,omitempty"`

	// ResourceDocumentation (resource_documentation) is an optional URL of a page containing
	// human-readable information for developers using the protected resource.
	// This value may be internationalized.
	ResourceDocumentation string `json:"resource_documentation,omitempty"`

	// ResourcePolicyURI (resource_policy_uri) is an optional URL of a page containing
	// human-readable policy information on how a client can use the data provided.
	// This value may be internationalized.
	ResourcePolicyURI string `json:"resource_policy_uri,omitempty"`

	// ResourceTOSURI (resource_tos_uri) is an optional URL of a page containing the protected
	// resource's human-readable terms of service. This value may be internationalized.
	ResourceTOSURI string `json:"resource_tos_uri,omitempty"`

	// TLSClientCertificateBoundAccessTokens (tls_client_certificate_bound_access_tokens) is an
	// optional boolean indicating support for mutual-TLS client certificate-bound
	// access tokens (RFC 8705). Defaults to false if omitted.
	TLSClientCertificateBoundAccessTokens bool `json:"tls_client_certificate_bound_access_tokens,omitempty"`

	// AuthorizationDetailsTypesSupported (authorization_details_types_supported) is an optional
	// slice of 'type' values supported by the resource server for the
	// 'authorization_details' parameter (RFC 9396).
	AuthorizationDetailsTypesSupported []string `json:"authorization_details_types_supported,omitempty"`

	// DPOPSigningAlgValuesSupported (dpop_signing_alg_values_supported) is an optional
	// slice of JWS signing algorithms supported by the resource server for validating
	// DPoP proof JWTs (RFC 9449).
	DPOPSigningAlgValuesSupported []string `json:"dpop_signing_alg_values_supported,omitempty"`

	// DPOPBoundAccessTokensRequired (dpop_bound_access_tokens_required) is an optional boolean
	// specifying whether the protected resource always requires the use of DPoP-bound
	// access tokens (RFC 9449). Defaults to false if omitted.
	DPOPBoundAccessTokensRequired bool `json:"dpop_bound_access_tokens_required,omitempty"`

	// SignedMetadata (signed_metadata) is an optional JWT containing metadata parameters
	// about the protected resource as claims. If present, these values take precedence
	// over values conveyed in plain JSON.
	// TODO:implement.
	// Note that §2.2 says it's okay to ignore this.
	// SignedMetadata string `json:"signed_metadata,omitempty"`
}

// GetProtectedResourceMetadataFromID issues a GET request to retrieve protected resource
// metadata from a resource server by its ID.
// The resource ID is an HTTPS URL, typically with a host:port and possibly a path.
// For example:
//
//	https://example.com/server
//
// This function, following the spec (§3), inserts the default well-known path into the
// URL. In our example, the result would be
//
//	https://example.com/.well-known/oauth-protected-resource/server
//
// It then retrieves the metadata at that location using the given client (or the
// default client if nil) and validates its resource field against resourceID.
func GetProtectedResourceMetadataFromID(ctx context.Context, resourceID string, c *http.Client) (_ *ProtectedResourceMetadata, err error) {
	defer util.Wrapf(&err, "GetProtectedResourceMetadataFromID(%q)", resourceID)

	u, err := url.Parse(resourceID)
	if err != nil {
		return nil, err
	}
	// Insert well-known URI into URL.
	u.Path = path.Join(defaultProtectedResourceMetadataURI, u.Path)
	return getPRM(ctx, u.String(), c, resourceID)
}

// GetProtectedResourceMetadataFromHeader retrieves protected resource metadata
// using information in the given header, using the given client (or the default
// client if nil).
// It issues a GET request to a URL discovered by parsing the WWW-Authenticate headers in the given request,
// It then validates the resource field of the resulting metadata against the given URL.
// If there is no URL in the request, it returns nil, nil.
func GetProtectedResourceMetadataFromHeader(ctx context.Context, header http.Header, c *http.Client) (_ *ProtectedResourceMetadata, err error) {
	defer util.Wrapf(&err, "GetProtectedResourceMetadataFromHeader")
	headers := header[http.CanonicalHeaderKey("WWW-Authenticate")]
	if len(headers) == 0 {
		return nil, nil
	}
	cs, err := parseWWWAuthenticate(headers)
	if err != nil {
		return nil, err
	}
	url := resourceMetadataURL(cs)
	if url == "" {
		return nil, nil
	}
	return getPRM(ctx, url, c, url)
}

// getPRM makes a GET request to the given URL, and validates the response.
// As part of the validation, it compares the returned resource field to wantResource.
func getPRM(ctx context.Context, url string, c *http.Client, wantResource string) (*ProtectedResourceMetadata, error) {
	if !strings.HasPrefix(strings.ToUpper(url), "HTTPS://") {
		return nil, fmt.Errorf("resource URL %q does not use HTTPS", url)
	}
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
	if err != nil {
		return nil, err
	}
	if c == nil {
		c = http.DefaultClient
	}
	res, err := c.Do(req)
	if err != nil {
		return nil, err
	}
	defer res.Body.Close()

	// Spec §3.2 requires a 200.
	if res.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("bad status %s", res.Status)
	}
	// Spec §3.2 requires application/json.
	if ct := res.Header.Get("Content-Type"); ct != "application/json" {
		return nil, fmt.Errorf("bad content type %q", ct)
	}

	var prm ProtectedResourceMetadata
	dec := json.NewDecoder(res.Body)
	if err := dec.Decode(&prm); err != nil {
		return nil, err
	}
	// Validate the Resource field to thwart impersonation attacks (section 3.3).
	if prm.Resource != wantResource {
		return nil, fmt.Errorf("got metadata resource %q, want %q", prm.Resource, wantResource)
	}
	return &prm, nil
}

// challenge represents a single authentication challenge from a WWW-Authenticate header.
// As per RFC 9110, Section 11.6.1, a challenge consists of a scheme and optional parameters.
type challenge struct {
	// GENERATED BY GEMINI 2.5.
	//
	// Scheme is the authentication scheme (e.g., "Bearer", "Basic").
	// It is case-insensitive. A parsed value will always be lower-case.
	Scheme string
	// Params is a map of authentication parameters.
	// Keys are case-insensitive. Parsed keys are always lower-case.
	Params map[string]string
}

// resourceMetadataURL returns a resource metadata URL from the given challenges,
// or the empty string if there is none.
func resourceMetadataURL(cs []challenge) string {
	for _, c := range cs {
		if u := c.Params["resource_metadata"]; u != "" {
			return u
		}
	}
	return ""
}

// parseWWWAuthenticate parses a WWW-Authenticate header string.
// The header format is defined in RFC 9110, Section 11.6.1, and can contain
// one or more challenges, separated by commas.
// It returns a slice of challenges or an error if one of the headers is malformed.
func parseWWWAuthenticate(headers []string) ([]challenge, error) {
	// GENERATED BY GEMINI 2.5 (human-tweaked)
	var challenges []challenge
	for _, h := range headers {
		challengeStrings, err := splitChallenges(h)
		if err != nil {
			return nil, err
		}
		for _, cs := range challengeStrings {
			if strings.TrimSpace(cs) == "" {
				continue
			}
			challenge, err := parseSingleChallenge(cs)
			if err != nil {
				return nil, fmt.Errorf("failed to parse challenge %q: %w", cs, err)
			}
			challenges = append(challenges, challenge)
		}
	}
	return challenges, nil
}

// splitChallenges splits a header value containing one or more challenges.
// It correctly handles commas within quoted strings and distinguishes between
// commas separating auth-params and commas separating challenges.
func splitChallenges(header string) ([]string, error) {
	// GENERATED BY GEMINI 2.5.
	var challenges []string
	inQuotes := false
	start := 0
	for i, r := range header {
		if r == '"' {
			if i > 0 && header[i-1] != '\\' {
				inQuotes = !inQuotes
			} else if i == 0 {
				// A challenge begins with an auth-scheme, which is a token, which cannot contain
				// a quote.
				return nil, errors.New(`challenge begins with '"'`)
			}
		} else if r == ',' && !inQuotes {
			// This is a potential challenge separator.
			// A new challenge does not start with `key=value`.
			// We check if the part after the comma looks like a parameter.
			lookahead := strings.TrimSpace(header[i+1:])
			eqPos := strings.Index(lookahead, "=")

			isParam := false
			if eqPos > 0 {
				// Check if the part before '=' is a single token (no spaces).
				token := lookahead[:eqPos]
				if strings.IndexFunc(token, unicode.IsSpace) == -1 {
					isParam = true
				}
			}

			if !isParam {
				// The part after the comma does not look like a parameter,
				// so this comma separates challenges.
				challenges = append(challenges, header[start:i])
				start = i + 1
			}
		}
	}
	// Add the last (or only) challenge to the list.
	challenges = append(challenges, header[start:])
	return challenges, nil
}

// parseSingleChallenge parses a string containing exactly one challenge.
// challenge   = auth-scheme [ 1*SP ( token68 / #auth-param ) ]
func parseSingleChallenge(s string) (challenge, error) {
	// GENERATED BY GEMINI 2.5, human-tweaked.
	s = strings.TrimSpace(s)
	if s == "" {
		return challenge{}, errors.New("empty challenge string")
	}

	scheme, paramsStr, found := strings.Cut(s, " ")
	c := challenge{Scheme: strings.ToLower(scheme)}
	if !found {
		return c, nil
	}

	params := make(map[string]string)

	// Parse the key-value parameters.
	for paramsStr != "" {
		// Find the end of the parameter key.
		keyEnd := strings.Index(paramsStr, "=")
		if keyEnd <= 0 {
			return challenge{}, fmt.Errorf("malformed auth parameter: expected key=value, but got %q", paramsStr)
		}
		key := strings.TrimSpace(paramsStr[:keyEnd])

		// Move the string past the key and the '='.
		paramsStr = strings.TrimSpace(paramsStr[keyEnd+1:])

		var value string
		if strings.HasPrefix(paramsStr, "\"") {
			// The value is a quoted string.
			paramsStr = paramsStr[1:] // Consume the opening quote.
			var valBuilder strings.Builder
			i := 0
			for ; i < len(paramsStr); i++ {
				// Handle escaped characters.
				if paramsStr[i] == '\\' && i+1 < len(paramsStr) {
					valBuilder.WriteByte(paramsStr[i+1])
					i++ // We've consumed two characters.
				} else if paramsStr[i] == '"' {
					// End of the quoted string.
					break
				} else {
					valBuilder.WriteByte(paramsStr[i])
				}
			}

			// A quoted string must be terminated.
			if i == len(paramsStr) {
				return challenge{}, fmt.Errorf("unterminated quoted string in auth parameter")
			}

			value = valBuilder.String()
			// Move the string past the value and the closing quote.
			paramsStr = strings.TrimSpace(paramsStr[i+1:])
		} else {
			// The value is a token. It ends at the next comma or the end of the string.
			commaPos := strings.Index(paramsStr, ",")
			if commaPos == -1 {
				value = paramsStr
				paramsStr = ""
			} else {
				value = strings.TrimSpace(paramsStr[:commaPos])
				paramsStr = strings.TrimSpace(paramsStr[commaPos:]) // Keep comma for next check
			}
		}
		if value == "" {
			return challenge{}, fmt.Errorf("no value for auth param %q", key)
		}

		// Per RFC 9110, parameter keys are case-insensitive.
		params[strings.ToLower(key)] = value

		// If there is a comma, consume it and continue to the next parameter.
		if strings.HasPrefix(paramsStr, ",") {
			paramsStr = strings.TrimSpace(paramsStr[1:])
		} else if paramsStr != "" {
			// If there's content but it's not a new parameter, the format is wrong.
			return challenge{}, fmt.Errorf("malformed auth parameter: expected comma after value, but got %q", paramsStr)
		}
	}

	// Per RFC 9110, the scheme is case-insensitive.
	return challenge{Scheme: strings.ToLower(scheme), Params: params}, nil
}


================================================
FILE: internal/mcp/internal/readme/Makefile
================================================
# This makefile builds ../README.md from the files in this directory.

OUTFILE=../../README.md

$(OUTFILE): build README.src.md
	go run golang.org/x/example/internal/cmd/weave@latest README.src.md > $(OUTFILE)

# Compile all the code used in the README.
build: $(wildcard */*.go)
	go build -o /tmp/mcp-readme/ ./...

# Preview the README on GitHub.
# $HOME/markdown must be a github repo.
# Visit https://github.com/$HOME/markdown to see the result.
preview: $(OUTFILE)
	cp $(OUTFILE) $$HOME/markdown/
	(cd $$HOME/markdown/ && git commit -m . README.md && git push)

.PHONY: build preview


================================================
FILE: internal/mcp/internal/readme/README.src.md
================================================
# MCP Go SDK

<!-- TODO: update pkgsite links here to point to the modelcontextprotocol
module, once it exists. -->

[![PkgGoDev](https://pkg.go.dev/badge/golang.org/x/tools)](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk)

This repository contains an implementation of the official Go software
development kit (SDK) for the Model Context Protocol (MCP).

**WARNING**: The SDK is currently unstable and subject to breaking changes.
Please test it out and file bug reports or API proposals. The [TODO](#todo)
section below outlines outstanding release blockers. We aim to release a stable
version of the SDK in mid July, 2025.

%toc

## Package documentation

The SDK consists of two importable packages:

- The
  [`github.com/modelcontextprotocol/go-sdk/mcp`](https://pkg.go.dev/golang.org/x/tools/internal/mcp)
  package defines the primary APIs for constructing and using MCP clients and
  servers.
- The
  [`github.com/modelcontextprotocol/go-sdk/jsonschema`](https://pkg.go.dev/golang.org/x/tools/internal/mcp/jsonschema)
  package provides an implementation of [JSON
  Schema](https://json-schema.org/), used for MCP tool input and output schema.

## Example

In this example, an MCP client communicates with an MCP server running in a
sidecar process:

%include client/client.go -

Here's an example of the corresponding server component, which communicates
with its client over stdin/stdout:

%include server/server.go -

The `examples/` directory contains more example clients and servers.

## TODO

The following TODOs block the release of this SDK:

- Better support for resumability in the Streamable HTTP transport: a
  server-side event store and client-side retry configuration.
- OAuth support (or examples of implementing OAuth using middleware).
- Support for the changes in the
  [2025-06-18](https://modelcontextprotocol.io/specification/2025-06-18/changelog)
  version of the MCP spec.
- More examples and documentation.

## Design

The design doc for this SDK is at [design.md](./design/design.md), which was
initially reviewed at
[modelcontextprotocol/discussions/364](https://github.com/orgs/modelcontextprotocol/discussions/364).

Further design discussion should occur in GitHub issues. See CONTRIBUTING.md
for details.

## Acknowledgements

Several existing Go MCP SDKs inspired the development and design of this
official SDK, notably [mcp-go](https://github.com/mark3labs/mcp-go), authored
by Ed Zynda. We are grateful to Ed as well as the other contributors to mcp-go,
and to authors and contributors of other SDKs such as
[mcp-golang](https://github.com/metoro-io/mcp-golang) and
[go-mcp](https://github.com/ThinkInAIXYZ/go-mcp). Thanks to their work, there
is a thriving ecosystem of Go MCP clients and servers.

## License

This project is licensed under the MIT License - see the [LICENSE](./LICENSE)
file for details.


================================================
FILE: internal/mcp/internal/readme/build.sh
================================================
#!/bin/sh

# Build README.md from the files in this directory.
# Must be invoked from the internal/cmp directory.

cd internal/readme

outfile=../../README.md

# Compile all the code used in the README.
go build -o /tmp/mcp-readme/ ./...
# Combine the code with the text in README.src.md.
# TODO: when at Go 1.24, use a tool directive for weave.
go run golang.org/x/example/internal/cmd/weave@latest README.src.md > $outfile

if [[ $1 = '-preview' ]]; then
	# Preview the README on GitHub.
	# $HOME/markdown must be a github repo.
	# Visit https://github.com/$HOME/markdown to see the result.
	cp $outfile $HOME/markdown/
	(cd $HOME/markdown/ && git commit -m . README.md && git push)
fi


================================================
FILE: internal/mcp/internal/readme/client/client.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// !+
package main

import (
	"context"
	"log"
	"os/exec"

	"golang.org/x/tools/internal/mcp"
)

func main() {
	ctx := context.Background()

	// Create a new client, with no features.
	client := mcp.NewClient("mcp-client", "v1.0.0", nil)

	// Connect to a server over stdin/stdout
	transport := mcp.NewCommandTransport(exec.Command("myserver"))
	session, err := client.Connect(ctx, transport)
	if err != nil {
		log.Fatal(err)
	}
	defer session.Close()

	// Call a tool on the server.
	params := &mcp.CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "you"},
	}
	res, err := session.CallTool(ctx, params)
	if err != nil {
		log.Fatalf("CallTool failed: %v", err)
	}
	if res.IsError {
		log.Fatal("tool failed")
	}
	for _, c := range res.Content {
		log.Print(c.Text)
	}
}

//!-


================================================
FILE: internal/mcp/internal/readme/server/server.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// !+
package main

import (
	"context"
	"log"

	"golang.org/x/tools/internal/mcp"
)

type HiParams struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, cc *mcp.ServerSession, params *mcp.CallToolParamsFor[HiParams]) (*mcp.CallToolResultFor[any], error) {
	return &mcp.CallToolResultFor[any]{
		Content: []*mcp.Content{mcp.NewTextContent("Hi " + params.Name)},
	}, nil
}

func main() {
	// Create a server with a single tool.
	server := mcp.NewServer("greeter", "v1.0.0", nil)
	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))
	// Run the server over stdin/stdout, until the client disconnects
	if err := server.Run(context.Background(), mcp.NewStdioTransport()); err != nil {
		log.Fatal(err)
	}
}

// !-


================================================
FILE: internal/mcp/internal/util/util.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package util

import (
	"fmt"
	"reflect"
	"strings"
)

type JSONInfo struct {
	Omit     bool            // unexported or first tag element is "-"
	Name     string          // Go field name or first tag element. Empty if Omit is true.
	Settings map[string]bool // "omitempty", "omitzero", etc.
}

// FieldJSONInfo reports information about how encoding/json
// handles the given struct field.
// If the field is unexported, JSONInfo.Omit is true and no other JSONInfo field
// is populated.
// If the field is exported and has no tag, then Name is the field's name and all
// other fields are false.
// Otherwise, the information is obtained from the tag.
func FieldJSONInfo(f reflect.StructField) JSONInfo {
	if !f.IsExported() {
		return JSONInfo{Omit: true}
	}
	info := JSONInfo{Name: f.Name}
	if tag, ok := f.Tag.Lookup("json"); ok {
		name, rest, found := strings.Cut(tag, ",")
		// "-" means omit, but "-," means the name is "-"
		if name == "-" && !found {
			return JSONInfo{Omit: true}
		}
		if name != "" {
			info.Name = name
		}
		if len(rest) > 0 {
			info.Settings = map[string]bool{}
			for s := range strings.SplitSeq(rest, ",") {
				info.Settings[s] = true
			}
		}
	}
	return info
}

// Wrapf wraps *errp with the given formatted message if *errp is not nil.
func Wrapf(errp *error, format string, args ...any) {
	if *errp != nil {
		*errp = fmt.Errorf("%s: %w", fmt.Sprintf(format, args...), *errp)
	}
}


================================================
FILE: internal/mcp/internal/util/util_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package util

import (
	"reflect"
	"testing"
)

func TestJSONInfo(t *testing.T) {
	type S struct {
		A int
		B int `json:","`
		C int `json:"-"`
		D int `json:"-,"`
		E int `json:"echo"`
		F int `json:"foxtrot,omitempty"`
		g int `json:"golf"` // vet reports "struct field g has json tag but is not exported"
	}
	want := []JSONInfo{
		{Name: "A"},
		{Name: "B"},
		{Omit: true},
		{Name: "-"},
		{Name: "echo"},
		{Name: "foxtrot", Settings: map[string]bool{"omitempty": true}},
		{Omit: true},
	}
	tt := reflect.TypeFor[S]()
	for i := range tt.NumField() {
		got := FieldJSONInfo(tt.Field(i))
		if !reflect.DeepEqual(got, want[i]) {
			t.Errorf("got %+v, want %+v", got, want[i])
		}
	}
}


================================================
FILE: internal/mcp/jsonschema/annotations.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import "maps"

// An annotations tracks certain properties computed by keywords that are used by validation.
// ("Annotation" is the spec's term.)
// In particular, the unevaluatedItems and unevaluatedProperties keywords need to know which
// items and properties were evaluated (validated successfully).
type annotations struct {
	allItems            bool            // all items were evaluated
	endIndex            int             // 1+largest index evaluated by prefixItems
	evaluatedIndexes    map[int]bool    // set of indexes evaluated by contains
	allProperties       bool            // all properties were evaluated
	evaluatedProperties map[string]bool // set of properties evaluated by various keywords
}

// noteIndex marks i as evaluated.
func (a *annotations) noteIndex(i int) {
	if a.evaluatedIndexes == nil {
		a.evaluatedIndexes = map[int]bool{}
	}
	a.evaluatedIndexes[i] = true
}

// noteEndIndex marks items with index less than end as evaluated.
func (a *annotations) noteEndIndex(end int) {
	if end > a.endIndex {
		a.endIndex = end
	}
}

// noteProperty marks prop as evaluated.
func (a *annotations) noteProperty(prop string) {
	if a.evaluatedProperties == nil {
		a.evaluatedProperties = map[string]bool{}
	}
	a.evaluatedProperties[prop] = true
}

// noteProperties marks all the properties in props as evaluated.
func (a *annotations) noteProperties(props map[string]bool) {
	a.evaluatedProperties = merge(a.evaluatedProperties, props)
}

// merge adds b's annotations to a.
// a must not be nil.
func (a *annotations) merge(b *annotations) {
	if b == nil {
		return
	}
	if b.allItems {
		a.allItems = true
	}
	if b.endIndex > a.endIndex {
		a.endIndex = b.endIndex
	}
	a.evaluatedIndexes = merge(a.evaluatedIndexes, b.evaluatedIndexes)
	if b.allProperties {
		a.allProperties = true
	}
	a.evaluatedProperties = merge(a.evaluatedProperties, b.evaluatedProperties)
}

// merge adds t's keys to s and returns s.
// If s is nil, it returns a copy of t.
func merge[K comparable](s, t map[K]bool) map[K]bool {
	if s == nil {
		return maps.Clone(t)
	}
	maps.Copy(s, t)
	return s
}


================================================
FILE: internal/mcp/jsonschema/doc.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package jsonschema is an implementation of the [JSON Schema specification],
a JSON-based format for describing the structure of JSON data.
The package can be used to read schemas for code generation, and to validate data using the
draft 2020-12 specification. Validation with other drafts or custom meta-schemas
is not supported.

Construct a [Schema] as you would any Go struct (for example, by writing a struct
literal), or unmarshal a JSON schema into a [Schema] in the usual way (with [encoding/json],
for instance). It can then be used for code generation or other purposes without
further processing.

# Validation

Before using a Schema to validate a JSON value, you must first resolve it by calling
[Schema.Resolve].
The call [Resolved.Validate] on the result to validate a JSON value.
The value must be a Go value that looks like the result of unmarshaling a JSON
value into an [any] or a struct. For example, the JSON value

	{"name": "Al", "scores": [90, 80, 100]}

could be represented as the Go value

	map[string]any{
		"name": "Al",
		"scores": []any{90, 80, 100},
	}

or as a value of this type:

	type Player struct {
		Name   string `json:"name"`
		Scores []int  `json:"scores"`
	}

# Inference

The [For] and [ForType] functions return a [Schema] describing the given Go type.
The type cannot contain any function or channel types, and any map types must have a string key.
For example, calling For on the above Player type results in this schema:

	{
	    "properties": {
	        "name": {
	            "type": "string"
	        },
	        "scores": {
	            "type": "array",
	            "items": {"type": "integer"}
	        }
	        "required": ["name", "scores"],
	        "additionalProperties": {"not": {}}
	    }
	}

# Deviations from the specification

Regular expressions are processed with Go's regexp package, which differs from ECMA 262,
most significantly in not supporting back-references.
See [this table of differences] for more.

The value of the "format" keyword is recorded in the Schema, but is ignored during validation.
It does not even produce [annotations].

[JSON Schema specification]: https://json-schema.org
[this table of differences] https://github.com/dlclark/regexp2?tab=readme-ov-file#compare-regexp-and-regexp2
[annotations]: https://json-schema.org/draft/2020-12/json-schema-core#name-annotations
*/
package jsonschema


================================================
FILE: internal/mcp/jsonschema/infer.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains functions that infer a schema from a Go type.

package jsonschema

import (
	"fmt"
	"reflect"

	"golang.org/x/tools/internal/mcp/internal/util"
)

// For constructs a JSON schema object for the given type argument.
//
// It is a convenience for ForType.
func For[T any]() (*Schema, error) {
	return ForType(reflect.TypeFor[T]())
}

// ForType constructs a JSON schema object for the given type.
// It translates Go types into compatible JSON schema types, as follows:
//   - strings have schema type "string"
//   - bools have schema type "boolean"
//   - signed and unsigned integer types have schema type "integer"
//   - floating point types have schema type "number"
//   - slices and arrays have schema type "array", and a corresponding schema
//     for items
//   - maps with string key have schema type "object", and corresponding
//     schema for additionalProperties
//   - structs have schema type "object", and disallow additionalProperties.
//     Their properties are derived from exported struct fields, using the
//     struct field json name. Fields that are marked "omitempty" are
//     considered optional; all other fields become required properties.
//
// It returns an error if t contains (possibly recursively) any of the following Go
// types, as they are incompatible with the JSON schema spec.
//   - maps with key other than 'string'
//   - function types
//   - complex numbers
//   - unsafe pointers
//
// The cannot be any cycles in the types.
// TODO(rfindley): we could perhaps just skip these incompatible fields.
func ForType(t reflect.Type) (*Schema, error) {
	return typeSchema(t)
}

func typeSchema(t reflect.Type) (*Schema, error) {
	// Follow pointers: the schema for *T is almost the same as for T, except that
	// an explicit JSON "null" is allowed for the pointer.
	allowNull := false
	for t.Kind() == reflect.Pointer {
		allowNull = true
		t = t.Elem()
	}

	var (
		s   = new(Schema)
		err error
	)

	switch t.Kind() {
	case reflect.Bool:
		s.Type = "boolean"

	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
		reflect.Uintptr:
		s.Type = "integer"

	case reflect.Float32, reflect.Float64:
		s.Type = "number"

	case reflect.Interface:
		// Unrestricted

	case reflect.Map:
		if t.Key().Kind() != reflect.String {
			return nil, fmt.Errorf("unsupported map key type %v", t.Key().Kind())
		}
		s.Type = "object"
		s.AdditionalProperties, err = typeSchema(t.Elem())
		if err != nil {
			return nil, fmt.Errorf("computing map value schema: %v", err)
		}

	case reflect.Slice, reflect.Array:
		s.Type = "array"
		s.Items, err = typeSchema(t.Elem())
		if err != nil {
			return nil, fmt.Errorf("computing element schema: %v", err)
		}
		if t.Kind() == reflect.Array {
			s.MinItems = Ptr(t.Len())
			s.MaxItems = Ptr(t.Len())
		}

	case reflect.String:
		s.Type = "string"

	case reflect.Struct:
		s.Type = "object"
		// no additional properties are allowed
		s.AdditionalProperties = falseSchema()

		for i := range t.NumField() {
			field := t.Field(i)
			info := util.FieldJSONInfo(field)
			if info.Omit {
				continue
			}
			if s.Properties == nil {
				s.Properties = make(map[string]*Schema)
			}
			s.Properties[info.Name], err = typeSchema(field.Type)
			if err != nil {
				return nil, err
			}
			if !info.Settings["omitempty"] && !info.Settings["omitzero"] {
				s.Required = append(s.Required, info.Name)
			}
		}

	default:
		return nil, fmt.Errorf("type %v is unsupported by jsonschema", t)
	}
	if allowNull && s.Type != "" {
		s.Types = []string{"null", s.Type}
		s.Type = ""
	}
	return s, nil
}


================================================
FILE: internal/mcp/jsonschema/infer_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema_test

import (
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

func forType[T any]() *jsonschema.Schema {
	s, err := jsonschema.For[T]()
	if err != nil {
		panic(err)
	}
	return s
}

func TestForType(t *testing.T) {
	type schema = jsonschema.Schema
	tests := []struct {
		name string
		got  *jsonschema.Schema
		want *jsonschema.Schema
	}{
		{"string", forType[string](), &schema{Type: "string"}},
		{"int", forType[int](), &schema{Type: "integer"}},
		{"int16", forType[int16](), &schema{Type: "integer"}},
		{"uint32", forType[int16](), &schema{Type: "integer"}},
		{"float64", forType[float64](), &schema{Type: "number"}},
		{"bool", forType[bool](), &schema{Type: "boolean"}},
		{"intmap", forType[map[string]int](), &schema{
			Type:                 "object",
			AdditionalProperties: &schema{Type: "integer"},
		}},
		{"anymap", forType[map[string]any](), &schema{
			Type:                 "object",
			AdditionalProperties: &schema{},
		}},
		{
			"struct",
			forType[struct {
				F           int `json:"f"`
				G           []float64
				P           *bool
				Skip        string `json:"-"`
				NoSkip      string `json:",omitempty"`
				unexported  float64
				unexported2 int `json:"No"` // vet reports "struct field unexported2 has json tag but is not exported"
			}](),
			&schema{
				Type: "object",
				Properties: map[string]*schema{
					"f":      {Type: "integer"},
					"G":      {Type: "array", Items: &schema{Type: "number"}},
					"P":      {Types: []string{"null", "boolean"}},
					"NoSkip": {Type: "string"},
				},
				Required:             []string{"f", "G", "P"},
				AdditionalProperties: &jsonschema.Schema{Not: &jsonschema.Schema{}},
			},
		},
		{
			"no sharing",
			forType[struct{ X, Y int }](),
			&schema{
				Type: "object",
				Properties: map[string]*schema{
					"X": {Type: "integer"},
					"Y": {Type: "integer"},
				},
				Required:             []string{"X", "Y"},
				AdditionalProperties: &jsonschema.Schema{Not: &jsonschema.Schema{}},
			},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			if diff := cmp.Diff(test.want, test.got, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
				t.Fatalf("ForType mismatch (-want +got):\n%s", diff)
			}
			// These schemas should all resolve.
			if _, err := test.got.Resolve(nil); err != nil {
				t.Fatalf("Resolving: %v", err)
			}
		})
	}
}


================================================
FILE: internal/mcp/jsonschema/json_pointer.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file implements JSON Pointers.
// A JSON Pointer is a path that refers to one JSON value within another.
// If the path is empty, it refers to the root value.
// Otherwise, it is a sequence of slash-prefixed strings, like "/points/1/x",
// selecting successive properties (for JSON objects) or items (for JSON arrays).
// For example, when applied to this JSON value:
//    {
// 	     "points": [
// 	 	    {"x": 1, "y": 2},
// 	 	    {"x": 3, "y": 4}
// 		 ]
//    }
//
// the JSON Pointer "/points/1/x" refers to the number 3.
// See the spec at https://datatracker.ietf.org/doc/html/rfc6901.

package jsonschema

import (
	"errors"
	"fmt"
	"reflect"
	"strconv"
	"strings"

	"golang.org/x/tools/internal/mcp/internal/util"
)

var (
	jsonPointerEscaper   = strings.NewReplacer("~", "~0", "/", "~1")
	jsonPointerUnescaper = strings.NewReplacer("~0", "~", "~1", "/")
)

func escapeJSONPointerSegment(s string) string {
	return jsonPointerEscaper.Replace(s)
}

func unescapeJSONPointerSegment(s string) string {
	return jsonPointerUnescaper.Replace(s)
}

// parseJSONPointer splits a JSON Pointer into a sequence of segments. It doesn't
// convert strings to numbers, because that depends on the traversal: a segment
// is treated as a number when applied to an array, but a string when applied to
// an object. See section 4 of the spec.
func parseJSONPointer(ptr string) (segments []string, err error) {
	if ptr == "" {
		return nil, nil
	}
	if ptr[0] != '/' {
		return nil, fmt.Errorf("JSON Pointer %q does not begin with '/'", ptr)
	}
	// Unlike file paths, consecutive slashes are not coalesced.
	// Split is nicer than Cut here, because it gets a final "/" right.
	segments = strings.Split(ptr[1:], "/")
	if strings.Contains(ptr, "~") {
		// Undo the simple escaping rules that allow one to include a slash in a segment.
		for i := range segments {
			segments[i] = unescapeJSONPointerSegment(segments[i])
		}
	}
	return segments, nil
}

// dereferenceJSONPointer returns the Schema that sptr points to within s,
// or an error if none.
// This implementation suffices for JSON Schema: pointers are applied only to Schemas,
// and refer only to Schemas.
func dereferenceJSONPointer(s *Schema, sptr string) (_ *Schema, err error) {
	defer util.Wrapf(&err, "JSON Pointer %q", sptr)

	segments, err := parseJSONPointer(sptr)
	if err != nil {
		return nil, err
	}
	v := reflect.ValueOf(s)
	for _, seg := range segments {
		switch v.Kind() {
		case reflect.Pointer:
			v = v.Elem()
			if !v.IsValid() {
				return nil, errors.New("navigated to nil reference")
			}
			fallthrough // if valid, can only be a pointer to a Schema

		case reflect.Struct:
			// The segment must refer to a field in a Schema.
			if v.Type() != reflect.TypeFor[Schema]() {
				return nil, fmt.Errorf("navigated to non-Schema %s", v.Type())
			}
			v = lookupSchemaField(v, seg)
			if !v.IsValid() {
				return nil, fmt.Errorf("no schema field %q", seg)
			}
		case reflect.Slice, reflect.Array:
			// The segment must be an integer without leading zeroes that refers to an item in the
			// slice or array.
			if seg == "-" {
				return nil, errors.New("the JSON Pointer array segment '-' is not supported")
			}
			if len(seg) > 1 && seg[0] == '0' {
				return nil, fmt.Errorf("segment %q has leading zeroes", seg)
			}
			n, err := strconv.Atoi(seg)
			if err != nil {
				return nil, fmt.Errorf("invalid int: %q", seg)
			}
			if n < 0 || n >= v.Len() {
				return nil, fmt.Errorf("index %d is out of bounds for array of length %d", n, v.Len())
			}
			v = v.Index(n)
			// Cannot be invalid.
		case reflect.Map:
			// The segment must be a key in the map.
			v = v.MapIndex(reflect.ValueOf(seg))
			if !v.IsValid() {
				return nil, fmt.Errorf("no key %q in map", seg)
			}
		default:
			return nil, fmt.Errorf("value %s (%s) is not a schema, slice or map", v, v.Type())
		}
	}
	if s, ok := v.Interface().(*Schema); ok {
		return s, nil
	}
	return nil, fmt.Errorf("does not refer to a schema, but to a %s", v.Type())
}

// lookupSchemaField returns the value of the field with the given name in v,
// or the zero value if there is no such field or it is not of type Schema or *Schema.
func lookupSchemaField(v reflect.Value, name string) reflect.Value {
	if name == "type" {
		// The "type" keyword may refer to Type or Types.
		// At most one will be non-zero.
		if t := v.FieldByName("Type"); !t.IsZero() {
			return t
		}
		return v.FieldByName("Types")
	}
	if sf, ok := schemaFieldMap[name]; ok {
		return v.FieldByIndex(sf.Index)
	}
	return reflect.Value{}
}


================================================
FILE: internal/mcp/jsonschema/json_pointer_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"strings"
	"testing"
)

func TestDereferenceJSONPointer(t *testing.T) {
	s := &Schema{
		AllOf: []*Schema{{}, {}},
		Defs: map[string]*Schema{
			"":  {Properties: map[string]*Schema{"": {}}},
			"A": {},
			"B": {
				Defs: map[string]*Schema{
					"X": {},
					"Y": {},
				},
			},
			"/~": {},
			"~1": {},
		},
	}

	for _, tt := range []struct {
		ptr  string
		want any
	}{
		{"", s},
		{"/$defs/A", s.Defs["A"]},
		{"/$defs/B", s.Defs["B"]},
		{"/$defs/B/$defs/X", s.Defs["B"].Defs["X"]},
		{"/$defs//properties/", s.Defs[""].Properties[""]},
		{"/allOf/1", s.AllOf[1]},
		{"/$defs/~1~0", s.Defs["/~"]},
		{"/$defs/~01", s.Defs["~1"]},
	} {
		got, err := dereferenceJSONPointer(s, tt.ptr)
		if err != nil {
			t.Fatal(err)
		}
		if got != tt.want {
			t.Errorf("%s:\ngot  %+v\nwant %+v", tt.ptr, got, tt.want)
		}
	}
}

func TestDerefernceJSONPointerErrors(t *testing.T) {
	s := &Schema{
		Type:     "t",
		Items:    &Schema{},
		Required: []string{"a"},
	}
	for _, tt := range []struct {
		ptr  string
		want string // error must contain this string
	}{
		{"x", "does not begin"}, // parse error: no initial '/'
		{"/minItems", "does not refer to a schema"},
		{"/minItems/x", "navigated to nil"},
		{"/required/-", "not supported"},
		{"/required/01", "leading zeroes"},
		{"/required/x", "invalid int"},
		{"/required/1", "out of bounds"},
		{"/properties/x", "no key"},
	} {
		_, err := dereferenceJSONPointer(s, tt.ptr)
		if err == nil {
			t.Errorf("%q: succeeded, want failure", tt.ptr)
		} else if !strings.Contains(err.Error(), tt.want) {
			t.Errorf("%q: error is %q, which does not contain %q", tt.ptr, err, tt.want)
		}
	}
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/applicator.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/applicator",
    "$dynamicAnchor": "meta",

    "title": "Applicator vocabulary meta-schema",
    "type": ["object", "boolean"],
    "properties": {
        "prefixItems": { "$ref": "#/$defs/schemaArray" },
        "items": { "$dynamicRef": "#meta" },
        "contains": { "$dynamicRef": "#meta" },
        "additionalProperties": { "$dynamicRef": "#meta" },
        "properties": {
            "type": "object",
            "additionalProperties": { "$dynamicRef": "#meta" },
            "default": {}
        },
        "patternProperties": {
            "type": "object",
            "additionalProperties": { "$dynamicRef": "#meta" },
            "propertyNames": { "format": "regex" },
            "default": {}
        },
        "dependentSchemas": {
            "type": "object",
            "additionalProperties": { "$dynamicRef": "#meta" },
            "default": {}
        },
        "propertyNames": { "$dynamicRef": "#meta" },
        "if": { "$dynamicRef": "#meta" },
        "then": { "$dynamicRef": "#meta" },
        "else": { "$dynamicRef": "#meta" },
        "allOf": { "$ref": "#/$defs/schemaArray" },
        "anyOf": { "$ref": "#/$defs/schemaArray" },
        "oneOf": { "$ref": "#/$defs/schemaArray" },
        "not": { "$dynamicRef": "#meta" }
    },
    "$defs": {
        "schemaArray": {
            "type": "array",
            "minItems": 1,
            "items": { "$dynamicRef": "#meta" }
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/content.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/content",
    "$dynamicAnchor": "meta",

    "title": "Content vocabulary meta-schema",

    "type": ["object", "boolean"],
    "properties": {
        "contentEncoding": { "type": "string" },
        "contentMediaType": { "type": "string" },
        "contentSchema": { "$dynamicRef": "#meta" }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/core.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/core",
    "$dynamicAnchor": "meta",

    "title": "Core vocabulary meta-schema",
    "type": ["object", "boolean"],
    "properties": {
        "$id": {
            "$ref": "#/$defs/uriReferenceString",
            "$comment": "Non-empty fragments not allowed.",
            "pattern": "^[^#]*#?$"
        },
        "$schema": { "$ref": "#/$defs/uriString" },
        "$ref": { "$ref": "#/$defs/uriReferenceString" },
        "$anchor": { "$ref": "#/$defs/anchorString" },
        "$dynamicRef": { "$ref": "#/$defs/uriReferenceString" },
        "$dynamicAnchor": { "$ref": "#/$defs/anchorString" },
        "$vocabulary": {
            "type": "object",
            "propertyNames": { "$ref": "#/$defs/uriString" },
            "additionalProperties": {
                "type": "boolean"
            }
        },
        "$comment": {
            "type": "string"
        },
        "$defs": {
            "type": "object",
            "additionalProperties": { "$dynamicRef": "#meta" }
        }
    },
    "$defs": {
        "anchorString": {
            "type": "string",
            "pattern": "^[A-Za-z_][-A-Za-z0-9._]*$"
        },
        "uriString": {
            "type": "string",
            "format": "uri"
        },
        "uriReferenceString": {
            "type": "string",
            "format": "uri-reference"
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/format-annotation.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/format-annotation",
    "$dynamicAnchor": "meta",

    "title": "Format vocabulary meta-schema for annotation results",
    "type": ["object", "boolean"],
    "properties": {
        "format": { "type": "string" }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/meta-data.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/meta-data",
    "$dynamicAnchor": "meta",

    "title": "Meta-data vocabulary meta-schema",

    "type": ["object", "boolean"],
    "properties": {
        "title": {
            "type": "string"
        },
        "description": {
            "type": "string"
        },
        "default": true,
        "deprecated": {
            "type": "boolean",
            "default": false
        },
        "readOnly": {
            "type": "boolean",
            "default": false
        },
        "writeOnly": {
            "type": "boolean",
            "default": false
        },
        "examples": {
            "type": "array",
            "items": true
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/unevaluated.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/unevaluated",
    "$dynamicAnchor": "meta",

    "title": "Unevaluated applicator vocabulary meta-schema",
    "type": ["object", "boolean"],
    "properties": {
        "unevaluatedItems": { "$dynamicRef": "#meta" },
        "unevaluatedProperties": { "$dynamicRef": "#meta" }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/meta/validation.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/meta/validation",
    "$dynamicAnchor": "meta",

    "title": "Validation vocabulary meta-schema",
    "type": ["object", "boolean"],
    "properties": {
        "type": {
            "anyOf": [
                { "$ref": "#/$defs/simpleTypes" },
                {
                    "type": "array",
                    "items": { "$ref": "#/$defs/simpleTypes" },
                    "minItems": 1,
                    "uniqueItems": true
                }
            ]
        },
        "const": true,
        "enum": {
            "type": "array",
            "items": true
        },
        "multipleOf": {
            "type": "number",
            "exclusiveMinimum": 0
        },
        "maximum": {
            "type": "number"
        },
        "exclusiveMaximum": {
            "type": "number"
        },
        "minimum": {
            "type": "number"
        },
        "exclusiveMinimum": {
            "type": "number"
        },
        "maxLength": { "$ref": "#/$defs/nonNegativeInteger" },
        "minLength": { "$ref": "#/$defs/nonNegativeIntegerDefault0" },
        "pattern": {
            "type": "string",
            "format": "regex"
        },
        "maxItems": { "$ref": "#/$defs/nonNegativeInteger" },
        "minItems": { "$ref": "#/$defs/nonNegativeIntegerDefault0" },
        "uniqueItems": {
            "type": "boolean",
            "default": false
        },
        "maxContains": { "$ref": "#/$defs/nonNegativeInteger" },
        "minContains": {
            "$ref": "#/$defs/nonNegativeInteger",
            "default": 1
        },
        "maxProperties": { "$ref": "#/$defs/nonNegativeInteger" },
        "minProperties": { "$ref": "#/$defs/nonNegativeIntegerDefault0" },
        "required": { "$ref": "#/$defs/stringArray" },
        "dependentRequired": {
            "type": "object",
            "additionalProperties": {
                "$ref": "#/$defs/stringArray"
            }
        }
    },
    "$defs": {
        "nonNegativeInteger": {
            "type": "integer",
            "minimum": 0
        },
        "nonNegativeIntegerDefault0": {
            "$ref": "#/$defs/nonNegativeInteger",
            "default": 0
        },
        "simpleTypes": {
            "enum": [
                "array",
                "boolean",
                "integer",
                "null",
                "number",
                "object",
                "string"
            ]
        },
        "stringArray": {
            "type": "array",
            "items": { "type": "string" },
            "uniqueItems": true,
            "default": []
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/meta-schemas/draft2020-12/schema.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "https://json-schema.org/draft/2020-12/schema",
    "$vocabulary": {
        "https://json-schema.org/draft/2020-12/vocab/core": true,
        "https://json-schema.org/draft/2020-12/vocab/applicator": true,
        "https://json-schema.org/draft/2020-12/vocab/unevaluated": true,
        "https://json-schema.org/draft/2020-12/vocab/validation": true,
        "https://json-schema.org/draft/2020-12/vocab/meta-data": true,
        "https://json-schema.org/draft/2020-12/vocab/format-annotation": true,
        "https://json-schema.org/draft/2020-12/vocab/content": true
    },
    "$dynamicAnchor": "meta",

    "title": "Core and Validation specifications meta-schema",
    "allOf": [
        {"$ref": "meta/core"},
        {"$ref": "meta/applicator"},
        {"$ref": "meta/unevaluated"},
        {"$ref": "meta/validation"},
        {"$ref": "meta/meta-data"},
        {"$ref": "meta/format-annotation"},
        {"$ref": "meta/content"}
    ],
    "type": ["object", "boolean"],
    "$comment": "This meta-schema also defines keywords that have appeared in previous drafts in order to prevent incompatible extensions as they remain in common use.",
    "properties": {
        "definitions": {
            "$comment": "\"definitions\" has been replaced by \"$defs\".",
            "type": "object",
            "additionalProperties": { "$dynamicRef": "#meta" },
            "deprecated": true,
            "default": {}
        },
        "dependencies": {
            "$comment": "\"dependencies\" has been split and replaced by \"dependentSchemas\" and \"dependentRequired\" in order to serve their differing semantics.",
            "type": "object",
            "additionalProperties": {
                "anyOf": [
                    { "$dynamicRef": "#meta" },
                    { "$ref": "meta/validation#/$defs/stringArray" }
                ]
            },
            "deprecated": true,
            "default": {}
        },
        "$recursiveAnchor": {
            "$comment": "\"$recursiveAnchor\" has been replaced by \"$dynamicAnchor\".",
            "$ref": "meta/core#/$defs/anchorString",
            "deprecated": true
        },
        "$recursiveRef": {
            "$comment": "\"$recursiveRef\" has been replaced by \"$dynamicRef\".",
            "$ref": "meta/core#/$defs/uriReferenceString",
            "deprecated": true
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/resolve.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file deals with preparing a schema for validation, including various checks,
// optimizations, and the resolution of cross-schema references.

package jsonschema

import (
	"errors"
	"fmt"
	"net/url"
	"reflect"
	"regexp"
	"strings"
)

// A Resolved consists of a [Schema] along with associated information needed to
// validate documents against it.
// A Resolved has been validated against its meta-schema, and all its references
// (the $ref and $dynamicRef keywords) have been resolved to their referenced Schemas.
// Call [Schema.Resolve] to obtain a Resolved from a Schema.
type Resolved struct {
	root *Schema
	// map from $ids to their schemas
	resolvedURIs map[string]*Schema
}

// Schema returns the schema that was resolved.
// It must not be modified.
func (r *Resolved) Schema() *Schema { return r.root }

// A Loader reads and unmarshals the schema at uri, if any.
type Loader func(uri *url.URL) (*Schema, error)

// ResolveOptions are options for [Schema.Resolve].
type ResolveOptions struct {
	// BaseURI is the URI relative to which the root schema should be resolved.
	// If non-empty, must be an absolute URI (one that starts with a scheme).
	// It is resolved (in the URI sense; see [url.ResolveReference]) with root's
	// $id property.
	// If the resulting URI is not absolute, then the schema cannot contain
	// relative URI references.
	BaseURI string
	// Loader loads schemas that are referred to by a $ref but are not under the
	// root schema (remote references).
	// If nil, resolving a remote reference will return an error.
	Loader Loader
	// ValidateDefaults determines whether to validate values of "default" keywords
	// against their schemas.
	// The [JSON Schema specification] does not require this, but it is
	// recommended if defaults will be used.
	//
	// [JSON Schema specification]: https://json-schema.org/understanding-json-schema/reference/annotations
	ValidateDefaults bool
}

// Resolve resolves all references within the schema and performs other tasks that
// prepare the schema for validation.
// If opts is nil, the default values are used.
func (root *Schema) Resolve(opts *ResolveOptions) (*Resolved, error) {
	// There are up to five steps required to prepare a schema to validate.
	// 1. Load: read the schema from somewhere and unmarshal it.
	//    This schema (root) may have been loaded or created in memory, but other schemas that
	//    come into the picture in step 4 will be loaded by the given loader.
	// 2. Check: validate the schema against a meta-schema, and perform other well-formedness checks.
	//    Precompute some values along the way.
	// 3. Resolve URIs: determine the base URI of the root and all its subschemas, and
	//    resolve (in the URI sense) all identifiers and anchors with their bases. This step results
	//    in a map from URIs to schemas within root.
	// 4. Resolve references: all refs in the schemas are replaced with the schema they refer to.
	// 5. (Optional.) If opts.ValidateDefaults is true, validate the defaults.
	if root.path != "" {
		return nil, fmt.Errorf("jsonschema: Resolve: %s already resolved", root)
	}
	r := &resolver{loaded: map[string]*Resolved{}}
	if opts != nil {
		r.opts = *opts
	}
	var base *url.URL
	if r.opts.BaseURI == "" {
		base = &url.URL{} // so we can call ResolveReference on it
	} else {
		var err error
		base, err = url.Parse(r.opts.BaseURI)
		if err != nil {
			return nil, fmt.Errorf("parsing base URI: %w", err)
		}
	}

	if r.opts.Loader == nil {
		r.opts.Loader = func(uri *url.URL) (*Schema, error) {
			return nil, errors.New("cannot resolve remote schemas: no loader passed to Schema.Resolve")
		}
	}

	resolved, err := r.resolve(root, base)
	if err != nil {
		return nil, err
	}
	if r.opts.ValidateDefaults {
		if err := resolved.validateDefaults(); err != nil {
			return nil, err
		}
	}
	// TODO: before we return, throw away anything we don't need for validation.
	return resolved, nil
}

// A resolver holds the state for resolution.
type resolver struct {
	opts ResolveOptions
	// A cache of loaded and partly resolved schemas. (They may not have had their
	// refs resolved.) The cache ensures that the loader will never be called more
	// than once with the same URI, and that reference cycles are handled properly.
	loaded map[string]*Resolved
}

func (r *resolver) resolve(s *Schema, baseURI *url.URL) (*Resolved, error) {
	if baseURI.Fragment != "" {
		return nil, fmt.Errorf("base URI %s must not have a fragment", baseURI)
	}
	if err := s.check(); err != nil {
		return nil, err
	}

	m, err := resolveURIs(s, baseURI)
	if err != nil {
		return nil, err
	}
	rs := &Resolved{root: s, resolvedURIs: m}
	// Remember the schema by both the URI we loaded it from and its canonical name,
	// which may differ if the schema has an $id.
	// We must set the map before calling resolveRefs, or ref cycles will cause unbounded recursion.
	r.loaded[baseURI.String()] = rs
	r.loaded[s.uri.String()] = rs

	if err := r.resolveRefs(rs); err != nil {
		return nil, err
	}
	return rs, nil
}

func (root *Schema) check() error {
	// Check for structural validity. Do this first and fail fast:
	// bad structure will cause other code to panic.
	if err := root.checkStructure(); err != nil {
		return err
	}

	var errs []error
	report := func(err error) { errs = append(errs, err) }

	for ss := range root.all() {
		ss.checkLocal(report)
	}
	return errors.Join(errs...)
}

// checkStructure verifies that root and its subschemas form a tree.
// It also assigns each schema a unique path, to improve error messages.
func (root *Schema) checkStructure() error {
	var check func(reflect.Value, []byte) error
	check = func(v reflect.Value, path []byte) error {
		// For the purpose of error messages, the root schema has path "root"
		// and other schemas' paths are their JSON Pointer from the root.
		p := "root"
		if len(path) > 0 {
			p = string(path)
		}
		s := v.Interface().(*Schema)
		if s == nil {
			return fmt.Errorf("jsonschema: schema at %s is nil", p)
		}
		if s.path != "" {
			// We've seen s before.
			// The schema graph at root is not a tree, but it needs to
			// be because we assume a unique parent when we store a schema's base
			// in the Schema. A cycle would also put Schema.all into an infinite
			// recursion.
			return fmt.Errorf("jsonschema: schemas at %s do not form a tree; %s appears more than once (also at %s)",
				root, s.path, p)
		}
		s.path = p

		for _, info := range schemaFieldInfos {
			fv := v.Elem().FieldByIndex(info.sf.Index)
			switch info.sf.Type {
			case schemaType:
				// A field that contains an individual schema.
				// A nil is valid: it just means the field isn't present.
				if !fv.IsNil() {
					if err := check(fv, fmt.Appendf(path, "/%s", info.jsonName)); err != nil {
						return err
					}
				}

			case schemaSliceType:
				for i := range fv.Len() {
					if err := check(fv.Index(i), fmt.Appendf(path, "/%s/%d", info.jsonName, i)); err != nil {
						return err
					}
				}

			case schemaMapType:
				iter := fv.MapRange()
				for iter.Next() {
					key := escapeJSONPointerSegment(iter.Key().String())
					if err := check(iter.Value(), fmt.Appendf(path, "/%s/%s", info.jsonName, key)); err != nil {
						return err
					}
				}
			}

		}
		return nil
	}

	return check(reflect.ValueOf(root), make([]byte, 0, 256))
}

// checkLocal checks s for validity, independently of other schemas it may refer to.
// Since checking a regexp involves compiling it, checkLocal saves those compiled regexps
// in the schema for later use.
// It appends the errors it finds to errs.
func (s *Schema) checkLocal(report func(error)) {
	addf := func(format string, args ...any) {
		msg := fmt.Sprintf(format, args...)
		report(fmt.Errorf("jsonschema.Schema: %s: %s", s, msg))
	}

	if s == nil {
		addf("nil subschema")
		return
	}
	if err := s.basicChecks(); err != nil {
		report(err)
		return
	}

	// TODO: validate the schema's properties,
	// ideally by jsonschema-validating it against the meta-schema.

	// Some properties are present so that Schemas can round-trip, but we do not
	// validate them.
	// Currently, it's just the $vocabulary property.
	// As a special case, we can validate the 2020-12 meta-schema.
	if s.Vocabulary != nil && s.Schema != draft202012 {
		addf("cannot validate a schema with $vocabulary")
	}

	// Check and compile regexps.
	if s.Pattern != "" {
		re, err := regexp.Compile(s.Pattern)
		if err != nil {
			addf("pattern: %v", err)
		} else {
			s.pattern = re
		}
	}
	if len(s.PatternProperties) > 0 {
		s.patternProperties = map[*regexp.Regexp]*Schema{}
		for reString, subschema := range s.PatternProperties {
			re, err := regexp.Compile(reString)
			if err != nil {
				addf("patternProperties[%q]: %v", reString, err)
				continue
			}
			s.patternProperties[re] = subschema
		}
	}

	// Build a set of required properties, to avoid quadratic behavior when validating
	// a struct.
	if len(s.Required) > 0 {
		s.isRequired = map[string]bool{}
		for _, r := range s.Required {
			s.isRequired[r] = true
		}
	}
}

// resolveURIs resolves the ids and anchors in all the schemas of root, relative
// to baseURI.
// See https://json-schema.org/draft/2020-12/json-schema-core#section-8.2, section
// 8.2.1.

// TODO(jba): dynamicAnchors (§8.2.2)
//
// Every schema has a base URI and a parent base URI.
//
// The parent base URI is the base URI of the lexically enclosing schema, or for
// a root schema, the URI it was loaded from or the one supplied to [Schema.Resolve].
//
// If the schema has no $id property, the base URI of a schema is that of its parent.
// If the schema does have an $id, it must be a URI, possibly relative. The schema's
// base URI is the $id resolved (in the sense of [url.URL.ResolveReference]) against
// the parent base.
//
// As an example, consider this schema loaded from http://a.com/root.json (quotes omitted):
//
//	{
//	    allOf: [
//	        {$id: "sub1.json", minLength: 5},
//	        {$id: "http://b.com", minimum: 10},
//	        {not: {maximum: 20}}
//	    ]
//	}
//
// The base URIs are as follows. Schema locations are expressed in the JSON Pointer notation.
//
//	schema         base URI
//	root           http://a.com/root.json
//	allOf/0        http://a.com/sub1.json
//	allOf/1        http://b.com (absolute $id; doesn't matter that it's not under the loaded URI)
//	allOf/2        http://a.com/root.json (inherited from parent)
//	allOf/2/not    http://a.com/root.json (inherited from parent)
func resolveURIs(root *Schema, baseURI *url.URL) (map[string]*Schema, error) {
	resolvedURIs := map[string]*Schema{}

	var resolve func(s, base *Schema) error
	resolve = func(s, base *Schema) error {
		// ids are scoped to the root.
		if s.ID != "" {
			// A non-empty ID establishes a new base.
			idURI, err := url.Parse(s.ID)
			if err != nil {
				return err
			}
			if idURI.Fragment != "" {
				return fmt.Errorf("$id %s must not have a fragment", s.ID)
			}
			// The base URI for this schema is its $id resolved against the parent base.
			s.uri = base.uri.ResolveReference(idURI)
			if !s.uri.IsAbs() {
				return fmt.Errorf("$id %s does not resolve to an absolute URI (base is %s)", s.ID, base.uri)
			}
			resolvedURIs[s.uri.String()] = s
			base = s // needed for anchors
		}
		s.base = base

		// Anchors and dynamic anchors are URI fragments that are scoped to their base.
		// We treat them as keys in a map stored within the schema.
		setAnchor := func(anchor string, dynamic bool) error {
			if anchor != "" {
				if _, ok := base.anchors[anchor]; ok {
					return fmt.Errorf("duplicate anchor %q in %s", anchor, base.uri)
				}
				if base.anchors == nil {
					base.anchors = map[string]anchorInfo{}
				}
				base.anchors[anchor] = anchorInfo{s, dynamic}
			}
			return nil
		}

		setAnchor(s.Anchor, false)
		setAnchor(s.DynamicAnchor, true)

		for c := range s.children() {
			if err := resolve(c, base); err != nil {
				return err
			}
		}
		return nil
	}

	// Set the root URI to the base for now. If the root has an $id, this will change.
	root.uri = baseURI
	// The original base, even if changed, is still a valid way to refer to the root.
	resolvedURIs[baseURI.String()] = root
	if err := resolve(root, root); err != nil {
		return nil, err
	}
	return resolvedURIs, nil
}

// resolveRefs replaces every ref in the schemas with the schema it refers to.
// A reference that doesn't resolve within the schema may refer to some other schema
// that needs to be loaded.
func (r *resolver) resolveRefs(rs *Resolved) error {
	for s := range rs.root.all() {
		if s.Ref != "" {
			refSchema, _, err := r.resolveRef(rs, s, s.Ref)
			if err != nil {
				return err
			}
			// Whether or not the anchor referred to by $ref fragment is dynamic,
			// the ref still treats it lexically.
			s.resolvedRef = refSchema
		}
		if s.DynamicRef != "" {
			refSchema, frag, err := r.resolveRef(rs, s, s.DynamicRef)
			if err != nil {
				return err
			}
			if frag != "" {
				// The dynamic ref's fragment points to a dynamic anchor.
				// We must resolve the fragment at validation time.
				s.dynamicRefAnchor = frag
			} else {
				// There is no dynamic anchor in the lexically referenced schema,
				// so the dynamic ref behaves like a lexical ref.
				s.resolvedDynamicRef = refSchema
			}
		}
	}
	return nil
}

// resolveRef resolves the reference ref, which is either s.Ref or s.DynamicRef.
func (r *resolver) resolveRef(rs *Resolved, s *Schema, ref string) (_ *Schema, dynamicFragment string, err error) {
	refURI, err := url.Parse(ref)
	if err != nil {
		return nil, "", err
	}
	// URI-resolve the ref against the current base URI to get a complete URI.
	refURI = s.base.uri.ResolveReference(refURI)
	// The non-fragment part of a ref URI refers to the base URI of some schema.
	// This part is the same for dynamic refs too: their non-fragment part resolves
	// lexically.
	u := *refURI
	u.Fragment = ""
	fraglessRefURI := &u
	// Look it up locally.
	referencedSchema := rs.resolvedURIs[fraglessRefURI.String()]
	if referencedSchema == nil {
		// The schema is remote. Maybe we've already loaded it.
		// We assume that the non-fragment part of refURI refers to a top-level schema
		// document. That is, we don't support the case exemplified by
		// http://foo.com/bar.json/baz, where the document is in bar.json and
		// the reference points to a subschema within it.
		// TODO: support that case.
		if lrs := r.loaded[fraglessRefURI.String()]; lrs != nil {
			referencedSchema = lrs.root
		} else {
			// Try to load the schema.
			ls, err := r.opts.Loader(fraglessRefURI)
			if err != nil {
				return nil, "", fmt.Errorf("loading %s: %w", fraglessRefURI, err)
			}
			lrs, err := r.resolve(ls, fraglessRefURI)
			if err != nil {
				return nil, "", err
			}
			referencedSchema = lrs.root
			assert(referencedSchema != nil, "nil referenced schema")
		}
	}

	frag := refURI.Fragment
	// Look up frag in refSchema.
	// frag is either a JSON Pointer or the name of an anchor.
	// A JSON Pointer is either the empty string or begins with a '/',
	// whereas anchors are always non-empty strings that don't contain slashes.
	if frag != "" && !strings.HasPrefix(frag, "/") {
		info, found := referencedSchema.anchors[frag]
		if !found {
			return nil, "", fmt.Errorf("no anchor %q in %s", frag, s)
		}
		if info.dynamic {
			dynamicFragment = frag
		}
		return info.schema, dynamicFragment, nil
	}
	// frag is a JSON Pointer.
	s, err = dereferenceJSONPointer(referencedSchema, frag)
	return s, "", err
}


================================================
FILE: internal/mcp/jsonschema/resolve_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"errors"
	"maps"
	"net/url"
	"regexp"
	"slices"
	"strings"
	"testing"
)

func TestSchemaStructure(t *testing.T) {
	check := func(s *Schema, want string) {
		t.Helper()
		err := s.checkStructure()
		if err == nil || !strings.Contains(err.Error(), want) {
			t.Errorf("checkStructure returned error %q, want %q", err, want)
		}
	}

	dag := &Schema{Type: "number"}
	dag = &Schema{Items: dag, Contains: dag}
	check(dag, "do not form a tree")

	tree := &Schema{Type: "number"}
	tree.Items = tree
	check(tree, "do not form a tree")

	sliceNil := &Schema{PrefixItems: []*Schema{nil}}
	check(sliceNil, "is nil")

	sliceMap := &Schema{Properties: map[string]*Schema{"a": nil}}
	check(sliceMap, "is nil")
}

func TestCheckLocal(t *testing.T) {
	for _, tt := range []struct {
		s    *Schema
		want string // error must be non-nil and match this regexp
	}{
		{
			&Schema{Pattern: "]["},
			"regexp",
		},
		{
			&Schema{PatternProperties: map[string]*Schema{"*": {}}},
			"regexp",
		},
	} {
		_, err := tt.s.Resolve(nil)
		if err == nil {
			t.Errorf("%s: unexpectedly passed", tt.s.json())
			continue
		}
		if !regexp.MustCompile(tt.want).MatchString(err.Error()) {
			t.Errorf("checkLocal returned error\n%q\nwanted it to match\n%s\nregexp: %s",
				tt.s.json(), err, tt.want)
		}
	}
}

func TestPaths(t *testing.T) {
	// CheckStructure should assign paths to schemas.
	// This test also verifies that Schema.all visits maps in sorted order.
	root := &Schema{
		Type:        "string",
		PrefixItems: []*Schema{{Type: "int"}, {Items: &Schema{Type: "null"}}},
		Contains: &Schema{Properties: map[string]*Schema{
			"~1": {Type: "boolean"},
			"p":  {},
		}},
	}

	type item struct {
		s *Schema
		p string
	}
	want := []item{
		{root, "root"},
		{root.Contains, "/contains"},
		{root.Contains.Properties["p"], "/contains/properties/p"},
		{root.Contains.Properties["~1"], "/contains/properties/~01"},
		{root.PrefixItems[0], "/prefixItems/0"},
		{root.PrefixItems[1], "/prefixItems/1"},
		{root.PrefixItems[1].Items, "/prefixItems/1/items"},
	}
	if err := root.checkStructure(); err != nil {
		t.Fatal(err)
	}

	var got []item
	for s := range root.all() {
		got = append(got, item{s, s.path})
	}
	if !slices.Equal(got, want) {
		t.Errorf("\ngot  %v\nwant %v", got, want)
	}
}

func TestResolveURIs(t *testing.T) {
	for _, baseURI := range []string{"", "http://a.com"} {
		t.Run(baseURI, func(t *testing.T) {
			root := &Schema{
				ID: "http://b.com",
				Items: &Schema{
					ID: "/foo.json",
				},
				Contains: &Schema{
					ID:            "/bar.json",
					Anchor:        "a",
					DynamicAnchor: "da",
					Items: &Schema{
						Anchor: "b",
						Items: &Schema{
							// An ID shouldn't be a query param, but this tests
							// resolving an ID with its parent.
							ID:     "?items",
							Anchor: "c",
						},
					},
				},
			}
			base, err := url.Parse(baseURI)
			if err != nil {
				t.Fatal(err)
			}
			got, err := resolveURIs(root, base)
			if err != nil {
				t.Fatal(err)
			}

			wantIDs := map[string]*Schema{
				baseURI:                       root,
				"http://b.com/foo.json":       root.Items,
				"http://b.com/bar.json":       root.Contains,
				"http://b.com/bar.json?items": root.Contains.Items.Items,
			}
			if baseURI != root.ID {
				wantIDs[root.ID] = root
			}
			wantAnchors := map[*Schema]map[string]anchorInfo{
				root.Contains: {
					"a":  anchorInfo{root.Contains, false},
					"da": anchorInfo{root.Contains, true},
					"b":  anchorInfo{root.Contains.Items, false},
				},
				root.Contains.Items.Items: {
					"c": anchorInfo{root.Contains.Items.Items, false},
				},
			}

			gotKeys := slices.Sorted(maps.Keys(got))
			wantKeys := slices.Sorted(maps.Keys(wantIDs))
			if !slices.Equal(gotKeys, wantKeys) {
				t.Errorf("ID keys:\ngot  %q\nwant %q", gotKeys, wantKeys)
			}
			if !maps.Equal(got, wantIDs) {
				t.Errorf("IDs:\ngot  %+v\n\nwant %+v", got, wantIDs)
			}
			for s := range root.all() {
				if want := wantAnchors[s]; want != nil {
					if got := s.anchors; !maps.Equal(got, want) {
						t.Errorf("anchors:\ngot  %+v\n\nwant %+v", got, want)
					}
				} else if s.anchors != nil {
					t.Errorf("non-nil anchors for %s", s)
				}
			}
		})
	}
}

func TestRefCycle(t *testing.T) {
	// Verify that cycles of refs are OK.
	// The test suite doesn't check this, surprisingly.
	schemas := map[string]*Schema{
		"root": {Ref: "a"},
		"a":    {Ref: "b"},
		"b":    {Ref: "a"},
	}

	loader := func(uri *url.URL) (*Schema, error) {
		s, ok := schemas[uri.Path[1:]]
		if !ok {
			return nil, errors.New("not found")
		}
		return s, nil
	}

	rs, err := schemas["root"].Resolve(&ResolveOptions{Loader: loader})
	if err != nil {
		t.Fatal(err)
	}

	check := func(s *Schema, key string) {
		t.Helper()
		if s.resolvedRef != schemas[key] {
			t.Errorf("%s resolvedRef != schemas[%q]", s.json(), key)
		}
	}

	check(rs.root, "a")
	check(schemas["a"], "b")
	check(schemas["b"], "a")
}


================================================
FILE: internal/mcp/jsonschema/schema.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"bytes"
	"cmp"
	"encoding/json"
	"errors"
	"fmt"
	"iter"
	"maps"
	"math"
	"net/url"
	"reflect"
	"regexp"
	"slices"

	"golang.org/x/tools/internal/mcp/internal/util"
)

// A Schema is a JSON schema object.
// It corresponds to the 2020-12 draft, as described in https://json-schema.org/draft/2020-12,
// specifically:
// - https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-01
// - https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01
//
// A Schema value may have non-zero values for more than one field:
// all relevant non-zero fields are used for validation.
// There is one exception to provide more Go type-safety: the Type and Types fields
// are mutually exclusive.
//
// Since this struct is a Go representation of a JSON value, it inherits JSON's
// distinction between nil and empty. Nil slices and maps are considered absent,
// but empty ones are present and affect validation. For example,
//
//	Schema{Enum: nil}
//
// is equivalent to an empty schema, so it validates every instance. But
//
//	Schema{Enum: []any{}}
//
// requires equality to some slice element, so it vacuously rejects every instance.
type Schema struct {
	// core
	ID      string             `json:"$id,omitempty"`
	Schema  string             `json:"$schema,omitempty"`
	Ref     string             `json:"$ref,omitempty"`
	Comment string             `json:"$comment,omitempty"`
	Defs    map[string]*Schema `json:"$defs,omitempty"`
	// definitions is deprecated but still allowed. It is a synonym for $defs.
	Definitions map[string]*Schema `json:"definitions,omitempty"`

	Anchor        string          `json:"$anchor,omitempty"`
	DynamicAnchor string          `json:"$dynamicAnchor,omitempty"`
	DynamicRef    string          `json:"$dynamicRef,omitempty"`
	Vocabulary    map[string]bool `json:"$vocabulary,omitempty"`

	// metadata
	Title       string          `json:"title,omitempty"`
	Description string          `json:"description,omitempty"`
	Default     json.RawMessage `json:"default,omitempty"`
	Deprecated  bool            `json:"deprecated,omitempty"`
	ReadOnly    bool            `json:"readOnly,omitempty"`
	WriteOnly   bool            `json:"writeOnly,omitempty"`
	Examples    []any           `json:"examples,omitempty"`

	// validation
	// Use Type for a single type, or Types for multiple types; never both.
	Type  string   `json:"-"`
	Types []string `json:"-"`
	Enum  []any    `json:"enum,omitempty"`
	// Const is *any because a JSON null (Go nil) is a valid value.
	Const            *any     `json:"const,omitempty"`
	MultipleOf       *float64 `json:"multipleOf,omitempty"`
	Minimum          *float64 `json:"minimum,omitempty"`
	Maximum          *float64 `json:"maximum,omitempty"`
	ExclusiveMinimum *float64 `json:"exclusiveMinimum,omitempty"`
	ExclusiveMaximum *float64 `json:"exclusiveMaximum,omitempty"`
	MinLength        *int     `json:"minLength,omitempty"`
	MaxLength        *int     `json:"maxLength,omitempty"`
	Pattern          string   `json:"pattern,omitempty"`

	// arrays
	PrefixItems      []*Schema `json:"prefixItems,omitempty"`
	Items            *Schema   `json:"items,omitempty"`
	MinItems         *int      `json:"minItems,omitempty"`
	MaxItems         *int      `json:"maxItems,omitempty"`
	AdditionalItems  *Schema   `json:"additionalItems,omitempty"`
	UniqueItems      bool      `json:"uniqueItems,omitempty"`
	Contains         *Schema   `json:"contains,omitempty"`
	MinContains      *int      `json:"minContains,omitempty"` // *int, not int: default is 1, not 0
	MaxContains      *int      `json:"maxContains,omitempty"`
	UnevaluatedItems *Schema   `json:"unevaluatedItems,omitempty"`

	// objects
	MinProperties         *int                `json:"minProperties,omitempty"`
	MaxProperties         *int                `json:"maxProperties,omitempty"`
	Required              []string            `json:"required,omitempty"`
	DependentRequired     map[string][]string `json:"dependentRequired,omitempty"`
	Properties            map[string]*Schema  `json:"properties,omitempty"`
	PatternProperties     map[string]*Schema  `json:"patternProperties,omitempty"`
	AdditionalProperties  *Schema             `json:"additionalProperties,omitempty"`
	PropertyNames         *Schema             `json:"propertyNames,omitempty"`
	UnevaluatedProperties *Schema             `json:"unevaluatedProperties,omitempty"`

	// logic
	AllOf []*Schema `json:"allOf,omitempty"`
	AnyOf []*Schema `json:"anyOf,omitempty"`
	OneOf []*Schema `json:"oneOf,omitempty"`
	Not   *Schema   `json:"not,omitempty"`

	// conditional
	If               *Schema            `json:"if,omitempty"`
	Then             *Schema            `json:"then,omitempty"`
	Else             *Schema            `json:"else,omitempty"`
	DependentSchemas map[string]*Schema `json:"dependentSchemas,omitempty"`

	// other
	// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-00#rfc.section.8
	ContentEncoding  string  `json:"contentEncoding,omitempty"`
	ContentMediaType string  `json:"contentMediaType,omitempty"`
	ContentSchema    *Schema `json:"contentSchema,omitempty"`

	// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-00#rfc.section.7
	Format string `json:"format,omitempty"`

	// computed fields

	// This schema's base schema.
	// If the schema is the root or has an ID, its base is itself.
	// Otherwise, its base is the innermost enclosing schema whose base
	// is itself.
	// Intuitively, a base schema is one that can be referred to with a
	// fragmentless URI.
	base *Schema

	// The URI for the schema, if it is the root or has an ID.
	// Otherwise nil.
	// Invariants:
	//   s.base.uri != nil.
	//   s.base == s <=> s.uri != nil
	uri *url.URL

	// The JSON Pointer path from the root schema to here.
	// Used in errors.
	path string

	// The schema to which Ref refers.
	resolvedRef *Schema

	// If the schema has a dynamic ref, exactly one of the next two fields
	// will be non-zero after successful resolution.
	// The schema to which the dynamic ref refers when it acts lexically.
	resolvedDynamicRef *Schema
	// The anchor to look up on the stack when the dynamic ref acts dynamically.
	dynamicRefAnchor string

	// Map from anchors to subschemas.
	anchors map[string]anchorInfo

	// compiled regexps
	pattern           *regexp.Regexp
	patternProperties map[*regexp.Regexp]*Schema

	// the set of required properties
	isRequired map[string]bool
}

// falseSchema returns a new Schema tree that fails to validate any value.
func falseSchema() *Schema {
	return &Schema{Not: &Schema{}}
}

// anchorInfo records the subschema to which an anchor refers, and whether
// the anchor keyword is $anchor or $dynamicAnchor.
type anchorInfo struct {
	schema  *Schema
	dynamic bool
}

// String returns a short description of the schema.
func (s *Schema) String() string {
	if s.uri != nil {
		if u := s.uri.String(); u != "" {
			return u
		}
	}
	if a := cmp.Or(s.Anchor, s.DynamicAnchor); a != "" {
		return fmt.Sprintf("%q, anchor %s", s.base.uri.String(), a)
	}
	if s.path != "" {
		return s.path
	}
	return "<anonymous schema>"
}

// ResolvedRef returns the Schema to which this schema's $ref keyword
// refers, or nil if it doesn't have a $ref.
// It returns nil if this schema has not been resolved, meaning that
// [Schema.Resolve] was called on it or one of its ancestors.
func (s *Schema) ResolvedRef() *Schema {
	return s.resolvedRef
}

func (s *Schema) basicChecks() error {
	if s.Type != "" && s.Types != nil {
		return errors.New("both Type and Types are set; at most one should be")
	}
	if s.Defs != nil && s.Definitions != nil {
		return errors.New("both Defs and Definitions are set; at most one should be")
	}
	return nil
}

type schemaWithoutMethods Schema // doesn't implement json.{Unm,M}arshaler

func (s *Schema) MarshalJSON() ([]byte, error) {
	if err := s.basicChecks(); err != nil {
		return nil, err
	}
	// Marshal either Type or Types as "type".
	var typ any
	switch {
	case s.Type != "":
		typ = s.Type
	case s.Types != nil:
		typ = s.Types
	}
	ms := struct {
		Type any `json:"type,omitempty"`
		*schemaWithoutMethods
	}{
		Type:                 typ,
		schemaWithoutMethods: (*schemaWithoutMethods)(s),
	}
	return json.Marshal(ms)
}

func (s *Schema) UnmarshalJSON(data []byte) error {
	// A JSON boolean is a valid schema.
	var b bool
	if err := json.Unmarshal(data, &b); err == nil {
		if b {
			// true is the empty schema, which validates everything.
			*s = Schema{}
		} else {
			// false is the schema that validates nothing.
			*s = *falseSchema()
		}
		return nil
	}

	ms := struct {
		Type          json.RawMessage `json:"type,omitempty"`
		Const         json.RawMessage `json:"const,omitempty"`
		MinLength     *integer        `json:"minLength,omitempty"`
		MaxLength     *integer        `json:"maxLength,omitempty"`
		MinItems      *integer        `json:"minItems,omitempty"`
		MaxItems      *integer        `json:"maxItems,omitempty"`
		MinProperties *integer        `json:"minProperties,omitempty"`
		MaxProperties *integer        `json:"maxProperties,omitempty"`
		MinContains   *integer        `json:"minContains,omitempty"`
		MaxContains   *integer        `json:"maxContains,omitempty"`

		*schemaWithoutMethods
	}{
		schemaWithoutMethods: (*schemaWithoutMethods)(s),
	}
	if err := json.Unmarshal(data, &ms); err != nil {
		return err
	}
	// Unmarshal "type" as either Type or Types.
	var err error
	if len(ms.Type) > 0 {
		switch ms.Type[0] {
		case '"':
			err = json.Unmarshal(ms.Type, &s.Type)
		case '[':
			err = json.Unmarshal(ms.Type, &s.Types)
		default:
			err = fmt.Errorf(`invalid value for "type": %q`, ms.Type)
		}
	}
	if err != nil {
		return err
	}

	unmarshalAnyPtr := func(p **any, raw json.RawMessage) error {
		if len(raw) == 0 {
			return nil
		}
		if bytes.Equal(raw, []byte("null")) {
			*p = new(any)
			return nil
		}
		return json.Unmarshal(raw, p)
	}

	// Setting Const to a pointer to null will marshal properly, but won't
	// unmarshal: the *any is set to nil, not a pointer to nil.
	if err := unmarshalAnyPtr(&s.Const, ms.Const); err != nil {
		return err
	}

	set := func(dst **int, src *integer) {
		if src != nil {
			*dst = Ptr(int(*src))
		}
	}

	set(&s.MinLength, ms.MinLength)
	set(&s.MaxLength, ms.MaxLength)
	set(&s.MinItems, ms.MinItems)
	set(&s.MaxItems, ms.MaxItems)
	set(&s.MinProperties, ms.MinProperties)
	set(&s.MaxProperties, ms.MaxProperties)
	set(&s.MinContains, ms.MinContains)
	set(&s.MaxContains, ms.MaxContains)

	return nil
}

type integer int32 // for the integer-valued fields of Schema

func (ip *integer) UnmarshalJSON(data []byte) error {
	if len(data) == 0 {
		// nothing to do
		return nil
	}
	// If there is a decimal point, src is a floating-point number.
	var i int64
	if bytes.ContainsRune(data, '.') {
		var f float64
		if err := json.Unmarshal(data, &f); err != nil {
			return errors.New("not a number")
		}
		i = int64(f)
		if float64(i) != f {
			return errors.New("not an integer value")
		}
	} else {
		if err := json.Unmarshal(data, &i); err != nil {
			return errors.New("cannot be unmarshaled into an int")
		}
	}
	// Ensure behavior is the same on both 32-bit and 64-bit systems.
	if i < math.MinInt32 || i > math.MaxInt32 {
		return errors.New("integer is out of range")
	}
	*ip = integer(i)
	return nil
}

// Ptr returns a pointer to a new variable whose value is x.
func Ptr[T any](x T) *T { return &x }

// every applies f preorder to every schema under s including s.
// The second argument to f is the path to the schema appended to the argument path.
// It stops when f returns false.
func (s *Schema) every(f func(*Schema) bool) bool {
	return f(s) && s.everyChild(func(s *Schema) bool { return s.every(f) })
}

// everyChild reports whether f is true for every immediate child schema of s.
func (s *Schema) everyChild(f func(*Schema) bool) bool {
	v := reflect.ValueOf(s)
	for _, info := range schemaFieldInfos {
		fv := v.Elem().FieldByIndex(info.sf.Index)
		switch info.sf.Type {
		case schemaType:
			// A field that contains an individual schema. A nil is valid: it just means the field isn't present.
			c := fv.Interface().(*Schema)
			if c != nil && !f(c) {
				return false
			}

		case schemaSliceType:
			slice := fv.Interface().([]*Schema)
			for _, c := range slice {
				if !f(c) {
					return false
				}
			}

		case schemaMapType:
			// Sort keys for determinism.
			m := fv.Interface().(map[string]*Schema)
			for _, k := range slices.Sorted(maps.Keys(m)) {
				if !f(m[k]) {
					return false
				}
			}
		}
	}
	return true
}

// all wraps every in an iterator.
func (s *Schema) all() iter.Seq[*Schema] {
	return func(yield func(*Schema) bool) { s.every(yield) }
}

// children wraps everyChild in an iterator.
func (s *Schema) children() iter.Seq[*Schema] {
	return func(yield func(*Schema) bool) { s.everyChild(yield) }
}

var (
	schemaType      = reflect.TypeFor[*Schema]()
	schemaSliceType = reflect.TypeFor[[]*Schema]()
	schemaMapType   = reflect.TypeFor[map[string]*Schema]()
)

type structFieldInfo struct {
	sf       reflect.StructField
	jsonName string
}

var (
	// the visible fields of Schema that have a JSON name, sorted by that name
	schemaFieldInfos []structFieldInfo
	// map from JSON name to field
	schemaFieldMap = map[string]reflect.StructField{}
)

func init() {
	for _, sf := range reflect.VisibleFields(reflect.TypeFor[Schema]()) {
		info := util.FieldJSONInfo(sf)
		if !info.Omit {
			schemaFieldInfos = append(schemaFieldInfos, structFieldInfo{sf, info.Name})
		}
	}
	slices.SortFunc(schemaFieldInfos, func(i1, i2 structFieldInfo) int {
		return cmp.Compare(i1.jsonName, i2.jsonName)
	})
	for _, info := range schemaFieldInfos {
		schemaFieldMap[info.jsonName] = info.sf
	}
}


================================================
FILE: internal/mcp/jsonschema/schema_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"encoding/json"
	"fmt"
	"math"
	"regexp"
	"testing"
)

func TestGoRoundTrip(t *testing.T) {
	// Verify that Go representations round-trip.
	for _, s := range []*Schema{
		{Type: "null"},
		{Types: []string{"null", "number"}},
		{Type: "string", MinLength: Ptr(20)},
		{Minimum: Ptr(20.0)},
		{Items: &Schema{Type: "integer"}},
		{Const: Ptr(any(0))},
		{Const: Ptr(any(nil))},
		{Const: Ptr(any([]int{}))},
		{Const: Ptr(any(map[string]any{}))},
		{Default: mustMarshal(1)},
		{Default: mustMarshal(nil)},
	} {
		data, err := json.Marshal(s)
		if err != nil {
			t.Fatal(err)
		}
		var got *Schema
		mustUnmarshal(t, data, &got)
		if !Equal(got, s) {
			t.Errorf("got %s, want %s", got.json(), s.json())
			if got.Const != nil && s.Const != nil {
				t.Logf("Consts: got %#v (%[1]T), want %#v (%[2]T)", *got.Const, *s.Const)
			}
		}
	}
}

func TestJSONRoundTrip(t *testing.T) {
	// Verify that JSON texts for schemas marshal into equivalent forms.
	// We don't expect everything to round-trip perfectly. For example, "true" and "false"
	// will turn into their object equivalents.
	// But most things should.
	// Some of these cases test Schema.{UnM,M}arshalJSON.
	// Most of others follow from the behavior of encoding/json, but they are still
	// valuable as regression tests of this package's behavior.
	for _, tt := range []struct {
		in, want string
	}{
		{`true`, `{}`}, // boolean schemas become object schemas
		{`false`, `{"not":{}}`},
		{`{"type":"", "enum":null}`, `{}`}, // empty fields are omitted
		{`{"minimum":1}`, `{"minimum":1}`},
		{`{"minimum":1.0}`, `{"minimum":1}`},     // floating-point integers lose their fractional part
		{`{"minLength":1.0}`, `{"minLength":1}`}, // some floats are unmarshaled into ints, but you can't tell
		{
			// map keys are sorted
			`{"$vocabulary":{"b":true, "a":false}}`,
			`{"$vocabulary":{"a":false,"b":true}}`,
		},
		{`{"unk":0}`, `{}`}, // unknown fields are dropped, unfortunately
	} {
		var s Schema
		mustUnmarshal(t, []byte(tt.in), &s)
		data, err := json.Marshal(s)
		if err != nil {
			t.Fatal(err)
		}
		if got := string(data); got != tt.want {
			t.Errorf("%s:\ngot  %s\nwant %s", tt.in, got, tt.want)
		}
	}
}

func TestUnmarshalErrors(t *testing.T) {
	for _, tt := range []struct {
		in   string
		want string // error must match this regexp
	}{
		{`1`, "cannot unmarshal number"},
		{`{"type":1}`, `invalid value for "type"`},
		{`{"minLength":1.5}`, `not an integer value`},
		{`{"maxLength":1.5}`, `not an integer value`},
		{`{"minItems":1.5}`, `not an integer value`},
		{`{"maxItems":1.5}`, `not an integer value`},
		{`{"minProperties":1.5}`, `not an integer value`},
		{`{"maxProperties":1.5}`, `not an integer value`},
		{`{"minContains":1.5}`, `not an integer value`},
		{`{"maxContains":1.5}`, `not an integer value`},
		{fmt.Sprintf(`{"maxContains":%d}`, int64(math.MaxInt32+1)), `out of range`},
		{`{"minLength":9e99}`, `cannot be unmarshaled`},
		{`{"minLength":"1.5"}`, `not a number`},
	} {
		var s Schema
		err := json.Unmarshal([]byte(tt.in), &s)
		if err == nil {
			t.Fatalf("%s: no error but expected one", tt.in)
		}
		if !regexp.MustCompile(tt.want).MatchString(err.Error()) {
			t.Errorf("%s: error %q does not match %q", tt.in, err, tt.want)
		}

	}
}

func mustUnmarshal(t *testing.T, data []byte, ptr any) {
	t.Helper()
	if err := json.Unmarshal(data, ptr); err != nil {
		t.Fatal(err)
	}
}

// json returns the schema in json format.
func (s *Schema) json() string {
	data, err := json.Marshal(s)
	if err != nil {
		return fmt.Sprintf("<jsonschema.Schema:%v>", err)
	}
	return string(data)
}

// json returns the schema in json format, indented.
func (s *Schema) jsonIndent() string {
	data, err := json.MarshalIndent(s, "", "  ")
	if err != nil {
		return fmt.Sprintf("<jsonschema.Schema:%v>", err)
	}
	return string(data)
}


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/README.md
================================================
# JSON Schema test suite for 2020-12

These files were copied from
https://github.com/json-schema-org/JSON-Schema-Test-Suite/tree/83e866b46c9f9e7082fd51e83a61c5f2145a1ab7/tests/draft2020-12.


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/additionalProperties.json
================================================
[
    {
        "description":
            "additionalProperties being false does not allow other properties",
        "specification": [ { "core":"10.3.2.3", "quote": "The value of \"additionalProperties\" MUST be a valid JSON Schema. Boolean \"false\" forbids everything." } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"foo": {}, "bar": {}},
            "patternProperties": { "^v": {} },
            "additionalProperties": false
        },
        "tests": [
            {
                "description": "no additional properties is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "an additional property is invalid",
                "data": {"foo" : 1, "bar" : 2, "quux" : "boom"},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": [1, 2, 3],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foobarbaz",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            },
            {
                "description": "patternProperties are not additional properties",
                "data": {"foo":1, "vroom": 2},
                "valid": true
            }
        ]
    },
    {
        "description": "non-ASCII pattern with additionalProperties",
        "specification": [ { "core":"10.3.2.3"} ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {"^á": {}},
            "additionalProperties": false
        },
        "tests": [
            {
                "description": "matching the pattern is valid",
                "data": {"ármányos": 2},
                "valid": true
            },
            {
                "description": "not matching the pattern is invalid",
                "data": {"élmény": 2},
                "valid": false
            }
        ]
    },
    {
        "description": "additionalProperties with schema",
        "specification": [ { "core":"10.3.2.3", "quote": "The value of \"additionalProperties\" MUST be a valid JSON Schema." } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"foo": {}, "bar": {}},
            "additionalProperties": {"type": "boolean"}
        },
        "tests": [
            {
                "description": "no additional properties is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "an additional valid property is valid",
                "data": {"foo" : 1, "bar" : 2, "quux" : true},
                "valid": true
            },
            {
                "description": "an additional invalid property is invalid",
                "data": {"foo" : 1, "bar" : 2, "quux" : 12},
                "valid": false
            }
        ]
    },
    {
        "description": "additionalProperties can exist by itself",
        "specification": [ { "core":"10.3.2.3", "quote": "With no other applicator applying to object instances. This validates all the instance values irrespective of their property names" } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "additionalProperties": {"type": "boolean"}
        },
        "tests": [
            {
                "description": "an additional valid property is valid",
                "data": {"foo" : true},
                "valid": true
            },
            {
                "description": "an additional invalid property is invalid",
                "data": {"foo" : 1},
                "valid": false
            }
        ]
    },
    {
        "description": "additionalProperties are allowed by default",
        "specification": [ { "core":"10.3.2.3", "quote": "Omitting this keyword has the same assertion behavior as an empty schema." } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"foo": {}, "bar": {}}
        },
        "tests": [
            {
                "description": "additional properties are allowed",
                "data": {"foo": 1, "bar": 2, "quux": true},
                "valid": true
            }
        ]
    },
    {
        "description": "additionalProperties does not look in applicators",
        "specification":[ { "core": "10.2", "quote": "Subschemas of applicator keywords evaluate the instance completely independently such that the results of one such subschema MUST NOT impact the results of sibling subschemas." } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {"properties": {"foo": {}}}
            ],
            "additionalProperties": {"type": "boolean"}
        },
        "tests": [
            {
                "description": "properties defined in allOf are not examined",
                "data": {"foo": 1, "bar": true},
                "valid": false
            }
        ]
    },
    {
        "description": "additionalProperties with null valued instance properties",
        "specification": [ { "core":"10.3.2.3" } ],
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "additionalProperties": {
                "type": "null"
            }
        },
        "tests": [
            {
                "description": "allows null values",
                "data": {"foo": null},
                "valid": true
            }
        ]
    },
    {
        "description": "additionalProperties with propertyNames",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": {
                "maxLength": 5
            },
            "additionalProperties": {
                "type": "number"
            }
        },
        "tests": [
            {
                "description": "Valid against both keywords",
                "data": { "apple": 4 },
                "valid": true
            },
            {
                "description": "Valid against propertyNames, but not additionalProperties",
                "data": { "fig": 2, "pear": "available" },
                "valid": false
            }
        ]
    },
    {
        "description": "dependentSchemas with additionalProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"foo2": {}},
            "dependentSchemas": {
                "foo" : {},
                "foo2": {
                    "properties": {
                        "bar": {}
                    }
                }
            },
            "additionalProperties": false
        },
        "tests": [
            {
                "description": "additionalProperties doesn't consider dependentSchemas",
                "data": {"foo": ""},
                "valid": false
            },
            {
                "description": "additionalProperties can't see bar",
                "data": {"bar": ""},
                "valid": false
            },
            {
                "description": "additionalProperties can't see bar even when foo2 is present",
                "data": {"foo2": "", "bar": ""},
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/allOf.json
================================================
[
    {
        "description": "allOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "properties": {
                        "bar": {"type": "integer"}
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "foo": {"type": "string"}
                    },
                    "required": ["foo"]
                }
            ]
        },
        "tests": [
            {
                "description": "allOf",
                "data": {"foo": "baz", "bar": 2},
                "valid": true
            },
            {
                "description": "mismatch second",
                "data": {"foo": "baz"},
                "valid": false
            },
            {
                "description": "mismatch first",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "wrong type",
                "data": {"foo": "baz", "bar": "quux"},
                "valid": false
            }
        ]
    },
    {
        "description": "allOf with base schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"bar": {"type": "integer"}},
            "required": ["bar"],
            "allOf" : [
                {
                    "properties": {
                        "foo": {"type": "string"}
                    },
                    "required": ["foo"]
                },
                {
                    "properties": {
                        "baz": {"type": "null"}
                    },
                    "required": ["baz"]
                }
            ]
        },
        "tests": [
            {
                "description": "valid",
                "data": {"foo": "quux", "bar": 2, "baz": null},
                "valid": true
            },
            {
                "description": "mismatch base schema",
                "data": {"foo": "quux", "baz": null},
                "valid": false
            },
            {
                "description": "mismatch first allOf",
                "data": {"bar": 2, "baz": null},
                "valid": false
            },
            {
                "description": "mismatch second allOf",
                "data": {"foo": "quux", "bar": 2},
                "valid": false
            },
            {
                "description": "mismatch both",
                "data": {"bar": 2},
                "valid": false
            }
        ]
    },
    {
        "description": "allOf simple types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {"maximum": 30},
                {"minimum": 20}
            ]
        },
        "tests": [
            {
                "description": "valid",
                "data": 25,
                "valid": true
            },
            {
                "description": "mismatch one",
                "data": 35,
                "valid": false
            }
        ]
    },
    {
        "description": "allOf with boolean schemas, all true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [true, true]
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "allOf with boolean schemas, some false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [true, false]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "allOf with boolean schemas, all false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [false, false]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "allOf with one empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {}
            ]
        },
        "tests": [
            {
                "description": "any data is valid",
                "data": 1,
                "valid": true
            }
        ]
    },
    {
        "description": "allOf with two empty schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {},
                {}
            ]
        },
        "tests": [
            {
                "description": "any data is valid",
                "data": 1,
                "valid": true
            }
        ]
    },
    {
        "description": "allOf with the first empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {},
                { "type": "number" }
            ]
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "allOf with the last empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                { "type": "number" },
                {}
            ]
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "nested allOf, to check validation semantics",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "allOf": [
                        {
                            "type": "null"
                        }
                    ]
                }
            ]
        },
        "tests": [
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "anything non-null is invalid",
                "data": 123,
                "valid": false
            }
        ]
    },
    {
        "description": "allOf combined with anyOf, oneOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [ { "multipleOf": 2 } ],
            "anyOf": [ { "multipleOf": 3 } ],
            "oneOf": [ { "multipleOf": 5 } ]
        },
        "tests": [
            {
                "description": "allOf: false, anyOf: false, oneOf: false",
                "data": 1,
                "valid": false
            },
            {
                "description": "allOf: false, anyOf: false, oneOf: true",
                "data": 5,
                "valid": false
            },
            {
                "description": "allOf: false, anyOf: true, oneOf: false",
                "data": 3,
                "valid": false
            },
            {
                "description": "allOf: false, anyOf: true, oneOf: true",
                "data": 15,
                "valid": false
            },
            {
                "description": "allOf: true, anyOf: false, oneOf: false",
                "data": 2,
                "valid": false
            },
            {
                "description": "allOf: true, anyOf: false, oneOf: true",
                "data": 10,
                "valid": false
            },
            {
                "description": "allOf: true, anyOf: true, oneOf: false",
                "data": 6,
                "valid": false
            },
            {
                "description": "allOf: true, anyOf: true, oneOf: true",
                "data": 30,
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/anchor.json
================================================
[
    {
        "description": "Location-independent identifier",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "#foo",
            "$defs": {
                "A": {
                    "$anchor": "foo",
                    "type": "integer"
                }
            }
        },
        "tests": [
            {
                "data": 1,
                "description": "match",
                "valid": true
            },
            {
                "data": "a",
                "description": "mismatch",
                "valid": false
            }
        ]
    },
    {
        "description": "Location-independent identifier with absolute URI",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/bar#foo",
            "$defs": {
                "A": {
                    "$id": "http://localhost:1234/draft2020-12/bar",
                    "$anchor": "foo",
                    "type": "integer"
                }
            }
        },
        "tests": [
            {
                "data": 1,
                "description": "match",
                "valid": true
            },
            {
                "data": "a",
                "description": "mismatch",
                "valid": false
            }
        ]
    },
    {
        "description": "Location-independent identifier with base URI change in subschema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/root",
            "$ref": "http://localhost:1234/draft2020-12/nested.json#foo",
            "$defs": {
                "A": {
                    "$id": "nested.json",
                    "$defs": {
                        "B": {
                            "$anchor": "foo",
                            "type": "integer"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "data": 1,
                "description": "match",
                "valid": true
            },
            {
                "data": "a",
                "description": "mismatch",
                "valid": false
            }
        ]
    },
    {
        "description": "same $anchor with different base uri",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/foobar",
            "$defs": {
                "A": {
                    "$id": "child1",
                    "allOf": [
                        {
                            "$id": "child2",
                            "$anchor": "my_anchor",
                            "type": "number"
                        },
                        {
                            "$anchor": "my_anchor",
                            "type": "string"
                        }
                    ]
                }
            },
            "$ref": "child1#my_anchor"
        },
        "tests": [
            {
                "description": "$ref resolves to /$defs/A/allOf/1",
                "data": "a",
                "valid": true
            },
            {
                "description": "$ref does not resolve to /$defs/A/allOf/0",
                "data": 1,
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/anyOf.json
================================================
[
    {
        "description": "anyOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [
                {
                    "type": "integer"
                },
                {
                    "minimum": 2
                }
            ]
        },
        "tests": [
            {
                "description": "first anyOf valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "second anyOf valid",
                "data": 2.5,
                "valid": true
            },
            {
                "description": "both anyOf valid",
                "data": 3,
                "valid": true
            },
            {
                "description": "neither anyOf valid",
                "data": 1.5,
                "valid": false
            }
        ]
    },
    {
        "description": "anyOf with base schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "string",
            "anyOf" : [
                {
                    "maxLength": 2
                },
                {
                    "minLength": 4
                }
            ]
        },
        "tests": [
            {
                "description": "mismatch base schema",
                "data": 3,
                "valid": false
            },
            {
                "description": "one anyOf valid",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "both anyOf invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "anyOf with boolean schemas, all true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [true, true]
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "anyOf with boolean schemas, some true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [true, false]
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "anyOf with boolean schemas, all false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [false, false]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "anyOf complex types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [
                {
                    "properties": {
                        "bar": {"type": "integer"}
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "foo": {"type": "string"}
                    },
                    "required": ["foo"]
                }
            ]
        },
        "tests": [
            {
                "description": "first anyOf valid (complex)",
                "data": {"bar": 2},
                "valid": true
            },
            {
                "description": "second anyOf valid (complex)",
                "data": {"foo": "baz"},
                "valid": true
            },
            {
                "description": "both anyOf valid (complex)",
                "data": {"foo": "baz", "bar": 2},
                "valid": true
            },
            {
                "description": "neither anyOf valid (complex)",
                "data": {"foo": 2, "bar": "quux"},
                "valid": false
            }
        ]
    },
    {
        "description": "anyOf with one empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [
                { "type": "number" },
                {}
            ]
        },
        "tests": [
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "number is valid",
                "data": 123,
                "valid": true
            }
        ]
    },
    {
        "description": "nested anyOf, to check validation semantics",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "anyOf": [
                {
                    "anyOf": [
                        {
                            "type": "null"
                        }
                    ]
                }
            ]
        },
        "tests": [
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "anything non-null is invalid",
                "data": 123,
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/boolean_schema.json
================================================
[
    {
        "description": "boolean schema 'true'",
        "schema": true,
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "boolean true is valid",
                "data": true,
                "valid": true
            },
            {
                "description": "boolean false is valid",
                "data": false,
                "valid": true
            },
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "object is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "array is valid",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "boolean schema 'false'",
        "schema": false,
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            },
            {
                "description": "boolean true is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "boolean false is invalid",
                "data": false,
                "valid": false
            },
            {
                "description": "null is invalid",
                "data": null,
                "valid": false
            },
            {
                "description": "object is invalid",
                "data": {"foo": "bar"},
                "valid": false
            },
            {
                "description": "empty object is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "array is invalid",
                "data": ["foo"],
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/const.json
================================================
[
    {
        "description": "const validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": 2
        },
        "tests": [
            {
                "description": "same value is valid",
                "data": 2,
                "valid": true
            },
            {
                "description": "another value is invalid",
                "data": 5,
                "valid": false
            },
            {
                "description": "another type is invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "const with object",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": {"foo": "bar", "baz": "bax"}
        },
        "tests": [
            {
                "description": "same object is valid",
                "data": {"foo": "bar", "baz": "bax"},
                "valid": true
            },
            {
                "description": "same object with different property order is valid",
                "data": {"baz": "bax", "foo": "bar"},
                "valid": true
            },
            {
                "description": "another object is invalid",
                "data": {"foo": "bar"},
                "valid": false
            },
            {
                "description": "another type is invalid",
                "data": [1, 2],
                "valid": false
            }
        ]
    },
    {
        "description": "const with array",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": [{ "foo": "bar" }]
        },
        "tests": [
            {
                "description": "same array is valid",
                "data": [{"foo": "bar"}],
                "valid": true
            },
            {
                "description": "another array item is invalid",
                "data": [2],
                "valid": false
            },
            {
                "description": "array with additional items is invalid",
                "data": [1, 2, 3],
                "valid": false
            }
        ]
    },
    {
        "description": "const with null",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": null
        },
        "tests": [
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "not null is invalid",
                "data": 0,
                "valid": false
            }
        ]
    },
    {
        "description": "const with false does not match 0",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": false
        },
        "tests": [
            {
                "description": "false is valid",
                "data": false,
                "valid": true
            },
            {
                "description": "integer zero is invalid",
                "data": 0,
                "valid": false
            },
            {
                "description": "float zero is invalid",
                "data": 0.0,
                "valid": false
            }
        ]
    },
    {
        "description": "const with true does not match 1",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": true
        },
        "tests": [
            {
                "description": "true is valid",
                "data": true,
                "valid": true
            },
            {
                "description": "integer one is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "float one is invalid",
                "data": 1.0,
                "valid": false
            }
        ]
    },
    {
        "description": "const with [false] does not match [0]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": [false]
        },
        "tests": [
            {
                "description": "[false] is valid",
                "data": [false],
                "valid": true
            },
            {
                "description": "[0] is invalid",
                "data": [0],
                "valid": false
            },
            {
                "description": "[0.0] is invalid",
                "data": [0.0],
                "valid": false
            }
        ]
    },
    {
        "description": "const with [true] does not match [1]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": [true]
        },
        "tests": [
            {
                "description": "[true] is valid",
                "data": [true],
                "valid": true
            },
            {
                "description": "[1] is invalid",
                "data": [1],
                "valid": false
            },
            {
                "description": "[1.0] is invalid",
                "data": [1.0],
                "valid": false
            }
        ]
    },
    {
        "description": "const with {\"a\": false} does not match {\"a\": 0}",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": {"a": false}
        },
        "tests": [
            {
                "description": "{\"a\": false} is valid",
                "data": {"a": false},
                "valid": true
            },
            {
                "description": "{\"a\": 0} is invalid",
                "data": {"a": 0},
                "valid": false
            },
            {
                "description": "{\"a\": 0.0} is invalid",
                "data": {"a": 0.0},
                "valid": false
            }
        ]
    },
    {
        "description": "const with {\"a\": true} does not match {\"a\": 1}",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": {"a": true}
        },
        "tests": [
            {
                "description": "{\"a\": true} is valid",
                "data": {"a": true},
                "valid": true
            },
            {
                "description": "{\"a\": 1} is invalid",
                "data": {"a": 1},
                "valid": false
            },
            {
                "description": "{\"a\": 1.0} is invalid",
                "data": {"a": 1.0},
                "valid": false
            }
        ]
    },
    {
        "description": "const with 0 does not match other zero-like types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": 0
        },
        "tests": [
            {
                "description": "false is invalid",
                "data": false,
                "valid": false
            },
            {
                "description": "integer zero is valid",
                "data": 0,
                "valid": true
            },
            {
                "description": "float zero is valid",
                "data": 0.0,
                "valid": true
            },
            {
                "description": "empty object is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            },
            {
                "description": "empty string is invalid",
                "data": "",
                "valid": false
            }
        ]
    },
    {
        "description": "const with 1 does not match true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": 1
        },
        "tests": [
            {
                "description": "true is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "integer one is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "float one is valid",
                "data": 1.0,
                "valid": true
            }
        ]
    },
    {
        "description": "const with -2.0 matches integer and float types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": -2.0
        },
        "tests": [
            {
                "description": "integer -2 is valid",
                "data": -2,
                "valid": true
            },
            {
                "description": "integer 2 is invalid",
                "data": 2,
                "valid": false
            },
            {
                "description": "float -2.0 is valid",
                "data": -2.0,
                "valid": true
            },
            {
                "description": "float 2.0 is invalid",
                "data": 2.0,
                "valid": false
            },
            {
                "description": "float -2.00001 is invalid",
                "data": -2.00001,
                "valid": false
            }
        ]
    },
    {
        "description": "float and integers are equal up to 64-bit representation limits",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": 9007199254740992
        },
        "tests": [
            {
                "description": "integer is valid",
                "data": 9007199254740992,
                "valid": true
            },
            {
                "description": "integer minus one is invalid",
                "data": 9007199254740991,
                "valid": false
            },
            {
                "description": "float is valid",
                "data": 9007199254740992.0,
                "valid": true
            },
            {
                "description": "float minus one is invalid",
                "data": 9007199254740991.0,
                "valid": false
            }
        ]
    },
    {
        "description": "nul characters in strings",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "const": "hello\u0000there"
        },
        "tests": [
            {
                "description": "match string with nul",
                "data": "hello\u0000there",
                "valid": true
            },
            {
                "description": "do not match string lacking nul",
                "data": "hellothere",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/contains.json
================================================
[
    {
        "description": "contains keyword validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"minimum": 5}
        },
        "tests": [
            {
                "description": "array with item matching schema (5) is valid",
                "data": [3, 4, 5],
                "valid": true
            },
            {
                "description": "array with item matching schema (6) is valid",
                "data": [3, 4, 6],
                "valid": true
            },
            {
                "description": "array with two items matching schema (5, 6) is valid",
                "data": [3, 4, 5, 6],
                "valid": true
            },
            {
                "description": "array without items matching schema is invalid",
                "data": [2, 3, 4],
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            },
            {
                "description": "not array is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "contains keyword with const keyword",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": { "const": 5 }
        },
        "tests": [
            {
                "description": "array with item 5 is valid",
                "data": [3, 4, 5],
                "valid": true
            },
            {
                "description": "array with two items 5 is valid",
                "data": [3, 4, 5, 5],
                "valid": true
            },
            {
                "description": "array without item 5 is invalid",
                "data": [1, 2, 3, 4],
                "valid": false
            }
        ]
    },
    {
        "description": "contains keyword with boolean schema true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": true
        },
        "tests": [
            {
                "description": "any non-empty array is valid",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            }
        ]
    },
    {
        "description": "contains keyword with boolean schema false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": false
        },
        "tests": [
            {
                "description": "any non-empty array is invalid",
                "data": ["foo"],
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            },
            {
                "description": "non-arrays are valid",
                "data": "contains does not apply to strings",
                "valid": true
            }
        ]
    },
    {
        "description": "items + contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": { "multipleOf": 2 },
            "contains": { "multipleOf": 3 }
        },
        "tests": [
            {
                "description": "matches items, does not match contains",
                "data": [ 2, 4, 8 ],
                "valid": false
            },
            {
                "description": "does not match items, matches contains",
                "data": [ 3, 6, 9 ],
                "valid": false
            },
            {
                "description": "matches both items and contains",
                "data": [ 6, 12 ],
                "valid": true
            },
            {
                "description": "matches neither items nor contains",
                "data": [ 1, 5 ],
                "valid": false
            }
        ]
    },
    {
        "description": "contains with false if subschema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {
                "if": false,
                "else": true
            }
        },
        "tests": [
            {
                "description": "any non-empty array is valid",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            }
        ]
    },
    {
        "description": "contains with null instance elements",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {
                "type": "null"
            }
        },
        "tests": [
            {
                "description": "allows null items",
                "data": [ null ],
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/default.json
================================================
[
    {
        "description": "invalid type for default",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {
                    "type": "integer",
                    "default": []
                }
            }
        },
        "tests": [
            {
                "description": "valid when property is specified",
                "data": {"foo": 13},
                "valid": true
            },
            {
                "description": "still valid when the invalid default is used",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "invalid string value for default",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "bar": {
                    "type": "string",
                    "minLength": 4,
                    "default": "bad"
                }
            }
        },
        "tests": [
            {
                "description": "valid when property is specified",
                "data": {"bar": "good"},
                "valid": true
            },
            {
                "description": "still valid when the invalid default is used",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "the default keyword does not do anything if the property is missing",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "alpha": {
                    "type": "number",
                    "maximum": 3,
                    "default": 5
                }
            }
        },
        "tests": [
            {
                "description": "an explicit property value is checked against maximum (passing)",
                "data": { "alpha": 1 },
                "valid": true
            },
            {
                "description": "an explicit property value is checked against maximum (failing)",
                "data": { "alpha": 5 },
                "valid": false
            },
            {
                "description": "missing properties are not filled in with the default",
                "data": {},
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/defs.json
================================================
[
    {
        "description": "validate definition against metaschema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "https://json-schema.org/draft/2020-12/schema"
        },
        "tests": [
            {
                "description": "valid definition schema",
                "data": {"$defs": {"foo": {"type": "integer"}}},
                "valid": true
            },
            {
                "description": "invalid definition schema",
                "data": {"$defs": {"foo": {"type": 1}}},
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/dependentRequired.json
================================================
[
    {
        "description": "single dependency",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentRequired": {"bar": ["foo"]}
        },
        "tests": [
            {
                "description": "neither",
                "data": {},
                "valid": true
            },
            {
                "description": "nondependant",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "with dependency",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "missing dependency",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": ["bar"],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "empty dependents",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentRequired": {"bar": []}
        },
        "tests": [
            {
                "description": "empty object",
                "data": {},
                "valid": true
            },
            {
                "description": "object with one property",
                "data": {"bar": 2},
                "valid": true
            },
            {
                "description": "non-object is valid",
                "data": 1,
                "valid": true
            }
        ]
    },
    {
        "description": "multiple dependents required",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentRequired": {"quux": ["foo", "bar"]}
        },
        "tests": [
            {
                "description": "neither",
                "data": {},
                "valid": true
            },
            {
                "description": "nondependants",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "with dependencies",
                "data": {"foo": 1, "bar": 2, "quux": 3},
                "valid": true
            },
            {
                "description": "missing dependency",
                "data": {"foo": 1, "quux": 2},
                "valid": false
            },
            {
                "description": "missing other dependency",
                "data": {"bar": 1, "quux": 2},
                "valid": false
            },
            {
                "description": "missing both dependencies",
                "data": {"quux": 1},
                "valid": false
            }
        ]
    },
    {
        "description": "dependencies with escaped characters",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentRequired": {
                "foo\nbar": ["foo\rbar"],
                "foo\"bar": ["foo'bar"]
            }
        },
        "tests": [
            {
                "description": "CRLF",
                "data": {
                    "foo\nbar": 1,
                    "foo\rbar": 2
                },
                "valid": true
            },
            {
                "description": "quoted quotes",
                "data": {
                    "foo'bar": 1,
                    "foo\"bar": 2
                },
                "valid": true
            },
            {
                "description": "CRLF missing dependent",
                "data": {
                    "foo\nbar": 1,
                    "foo": 2
                },
                "valid": false
            },
            {
                "description": "quoted quotes missing dependent",
                "data": {
                    "foo\"bar": 2
                },
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/dependentSchemas.json
================================================
[
    {
        "description": "single dependency",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentSchemas": {
                "bar": {
                    "properties": {
                        "foo": {"type": "integer"},
                        "bar": {"type": "integer"}
                    }
                }
            }
        },
        "tests": [
            {
                "description": "valid",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "no dependency",
                "data": {"foo": "quux"},
                "valid": true
            },
            {
                "description": "wrong type",
                "data": {"foo": "quux", "bar": 2},
                "valid": false
            },
            {
                "description": "wrong type other",
                "data": {"foo": 2, "bar": "quux"},
                "valid": false
            },
            {
                "description": "wrong type both",
                "data": {"foo": "quux", "bar": "quux"},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": ["bar"],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "boolean subschemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentSchemas": {
                "foo": true,
                "bar": false
            }
        },
        "tests": [
            {
                "description": "object with property having schema true is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "object with property having schema false is invalid",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "object with both properties is invalid",
                "data": {"foo": 1, "bar": 2},
                "valid": false
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "dependencies with escaped characters",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "dependentSchemas": {
                "foo\tbar": {"minProperties": 4},
                "foo'bar": {"required": ["foo\"bar"]}
            }
        },
        "tests": [
            {
                "description": "quoted tab",
                "data": {
                    "foo\tbar": 1,
                    "a": 2,
                    "b": 3,
                    "c": 4
                },
                "valid": true
            },
            {
                "description": "quoted quote",
                "data": {
                    "foo'bar": {"foo\"bar": 1}
                },
                "valid": false
            },
            {
                "description": "quoted tab invalid under dependent schema",
                "data": {
                    "foo\tbar": 1,
                    "a": 2
                },
                "valid": false
            },
            {
                "description": "quoted quote invalid under dependent schema",
                "data": {"foo'bar": 1},
                "valid": false
            }
        ]
    },
    {
        "description": "dependent subschema incompatible with root",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {}
            },
            "dependentSchemas": {
                "foo": {
                    "properties": {
                        "bar": {}
                    },
                    "additionalProperties": false
                }
            }
        },
        "tests": [
            {
                "description": "matches root",
                "data": {"foo": 1},
                "valid": false
            },
            {
                "description": "matches dependency",
                "data": {"bar": 1},
                "valid": true
            },
            {
                "description": "matches both",
                "data": {"foo": 1, "bar": 2},
                "valid": false
            },
            {
                "description": "no dependency",
                "data": {"baz": 1},
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/dynamicRef.json
================================================
[
    {
        "description": "A $dynamicRef to a $dynamicAnchor in the same schema resource behaves like a normal $ref to an $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamicRef-dynamicAnchor-same-schema/root",
            "type": "array",
            "items": { "$dynamicRef": "#items" },
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is valid",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "An array containing non-strings is invalid",
                "data": ["foo", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "A $dynamicRef to an $anchor in the same schema resource behaves like a normal $ref to an $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamicRef-anchor-same-schema/root",
            "type": "array",
            "items": { "$dynamicRef": "#items" },
            "$defs": {
                "foo": {
                    "$anchor": "items",
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is valid",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "An array containing non-strings is invalid",
                "data": ["foo", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "A $ref to a $dynamicAnchor in the same schema resource behaves like a normal $ref to an $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/ref-dynamicAnchor-same-schema/root",
            "type": "array",
            "items": { "$ref": "#items" },
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is valid",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "An array containing non-strings is invalid",
                "data": ["foo", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "A $dynamicRef resolves to the first $dynamicAnchor still in scope that is encountered when the schema is evaluated",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/typical-dynamic-resolution/root",
            "$ref": "list",
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#items" },
                    "$defs": {
                      "items": {
                          "$comment": "This is only needed to satisfy the bookending requirement",
                          "$dynamicAnchor": "items"
                      }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is valid",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "An array containing non-strings is invalid",
                "data": ["foo", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "A $dynamicRef without anchor in fragment behaves identical to $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamicRef-without-anchor/root",
            "$ref": "list",
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#/$defs/items" },
                    "$defs": {
                      "items": {
                          "$comment": "This is only needed to satisfy the bookending requirement",
                          "$dynamicAnchor": "items",
                          "type": "number"
                      }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is invalid",
                "data": ["foo", "bar"],
                "valid": false
            },
            {
                "description": "An array of numbers is valid",
                "data": [24, 42],
                "valid": true
            }
        ]
    },
    {
        "description": "A $dynamicRef with intermediate scopes that don't include a matching $dynamicAnchor does not affect dynamic scope resolution",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-resolution-with-intermediate-scopes/root",
            "$ref": "intermediate-scope",
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                },
                "intermediate-scope": {
                    "$id": "intermediate-scope",
                    "$ref": "list"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#items" },
                    "$defs": {
                      "items": {
                          "$comment": "This is only needed to satisfy the bookending requirement",
                          "$dynamicAnchor": "items"
                      }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "An array of strings is valid",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "An array containing non-strings is invalid",
                "data": ["foo", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "An $anchor with the same name as a $dynamicAnchor is not used for dynamic scope resolution",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-resolution-ignores-anchors/root",
            "$ref": "list",
            "$defs": {
                "foo": {
                    "$anchor": "items",
                    "type": "string"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#items" },
                    "$defs": {
                      "items": {
                          "$comment": "This is only needed to satisfy the bookending requirement",
                          "$dynamicAnchor": "items"
                      }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "Any array is valid",
                "data": ["foo", 42],
                "valid": true
            }
        ]
    },
    {
        "description": "A $dynamicRef without a matching $dynamicAnchor in the same schema resource behaves like a normal $ref to $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-resolution-without-bookend/root",
            "$ref": "list",
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#items" },
                    "$defs": {
                        "items": {
                            "$comment": "This is only needed to give the reference somewhere to resolve to when it behaves like $ref",
                            "$anchor": "items"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "Any array is valid",
                "data": ["foo", 42],
                "valid": true
            }
        ]
    },
    {
        "description": "A $dynamicRef with a non-matching $dynamicAnchor in the same schema resource behaves like a normal $ref to $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/unmatched-dynamic-anchor/root",
            "$ref": "list",
            "$defs": {
                "foo": {
                    "$dynamicAnchor": "items",
                    "type": "string"
                },
                "list": {
                    "$id": "list",
                    "type": "array",
                    "items": { "$dynamicRef": "#items" },
                    "$defs": {
                        "items": {
                            "$comment": "This is only needed to give the reference somewhere to resolve to when it behaves like $ref",
                            "$anchor": "items",
                            "$dynamicAnchor": "foo"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "Any array is valid",
                "data": ["foo", 42],
                "valid": true
            }
        ]
    },
    {
        "description": "A $dynamicRef that initially resolves to a schema with a matching $dynamicAnchor resolves to the first $dynamicAnchor in the dynamic scope",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/relative-dynamic-reference/root",
            "$dynamicAnchor": "meta",
            "type": "object",
            "properties": {
                "foo": { "const": "pass" }
            },
            "$ref": "extended",
            "$defs": {
                "extended": {
                    "$id": "extended",
                    "$dynamicAnchor": "meta",
                    "type": "object",
                    "properties": {
                        "bar": { "$ref": "bar" }
                    }
                },
                "bar": {
                    "$id": "bar",
                    "type": "object",
                    "properties": {
                        "baz": { "$dynamicRef": "extended#meta" }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "The recursive part is valid against the root",
                "data": {
                    "foo": "pass",
                    "bar": {
                        "baz": { "foo": "pass" }
                    }
                },
                "valid": true
            },
            {
                "description": "The recursive part is not valid against the root",
                "data": {
                    "foo": "pass",
                    "bar": {
                        "baz": { "foo": "fail" }
                    }
                },
                "valid": false
            }
        ]
    },
    {
        "description": "A $dynamicRef that initially resolves to a schema without a matching $dynamicAnchor behaves like a normal $ref to $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/relative-dynamic-reference-without-bookend/root",
            "$dynamicAnchor": "meta",
            "type": "object",
            "properties": {
                "foo": { "const": "pass" }
            },
            "$ref": "extended",
            "$defs": {
                "extended": {
                    "$id": "extended",
                    "$anchor": "meta",
                    "type": "object",
                    "properties": {
                        "bar": { "$ref": "bar" }
                    }
                },
                "bar": {
                    "$id": "bar",
                    "type": "object",
                    "properties": {
                        "baz": { "$dynamicRef": "extended#meta" }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "The recursive part doesn't need to validate against the root",
                "data": {
                    "foo": "pass",
                    "bar": {
                        "baz": { "foo": "fail" }
                    }
                },
                "valid": true
            }
        ]
    },
    {
        "description": "multiple dynamic paths to the $dynamicRef keyword",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-ref-with-multiple-paths/main",
            "if": {
                "properties": {
                    "kindOfList": { "const": "numbers" }
                },
                "required": ["kindOfList"]
            },
            "then": { "$ref": "numberList" },
            "else": { "$ref": "stringList" },

            "$defs": {
                "genericList": {
                    "$id": "genericList",
                    "properties": {
                        "list": {
                            "items": { "$dynamicRef": "#itemType" }
                        }
                    },
                    "$defs": {
                        "defaultItemType": {
                            "$comment": "Only needed to satisfy bookending requirement",
                            "$dynamicAnchor": "itemType"
                        }
                    }
                },
                "numberList": {
                    "$id": "numberList",
                    "$defs": {
                        "itemType": {
                            "$dynamicAnchor": "itemType",
                            "type": "number"
                        }
                    },
                    "$ref": "genericList"
                },
                "stringList": {
                    "$id": "stringList",
                    "$defs": {
                        "itemType": {
                            "$dynamicAnchor": "itemType",
                            "type": "string"
                        }
                    },
                    "$ref": "genericList"
                }
            }
        },
        "tests": [
            {
                "description": "number list with number values",
                "data": {
                    "kindOfList": "numbers",
                    "list": [1.1]
                },
                "valid": true
            },
            {
                "description": "number list with string values",
                "data": {
                    "kindOfList": "numbers",
                    "list": ["foo"]
                },
                "valid": false
            },
            {
                "description": "string list with number values",
                "data": {
                    "kindOfList": "strings",
                    "list": [1.1]
                },
                "valid": false
            },
            {
                "description": "string list with string values",
                "data": {
                    "kindOfList": "strings",
                    "list": ["foo"]
                },
                "valid": true
            }
        ]
    },
    {
        "description": "after leaving a dynamic scope, it is not used by a $dynamicRef",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-ref-leaving-dynamic-scope/main",
            "if": {
                "$id": "first_scope",
                "$defs": {
                    "thingy": {
                        "$comment": "this is first_scope#thingy",
                        "$dynamicAnchor": "thingy",
                        "type": "number"
                    }
                }
            },
            "then": {
                "$id": "second_scope",
                "$ref": "start",
                "$defs": {
                    "thingy": {
                        "$comment": "this is second_scope#thingy, the final destination of the $dynamicRef",
                        "$dynamicAnchor": "thingy",
                        "type": "null"
                    }
                }
            },
            "$defs": {
                "start": {
                    "$comment": "this is the landing spot from $ref",
                    "$id": "start",
                    "$dynamicRef": "inner_scope#thingy"
                },
                "thingy": {
                    "$comment": "this is the first stop for the $dynamicRef",
                    "$id": "inner_scope",
                    "$dynamicAnchor": "thingy",
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "string matches /$defs/thingy, but the $dynamicRef does not stop here",
                "data": "a string",
                "valid": false
            },
            {
                "description": "first_scope is not in dynamic scope for the $dynamicRef",
                "data": 42,
                "valid": false
            },
            {
                "description": "/then/$defs/thingy is the final stop for the $dynamicRef",
                "data": null,
                "valid": true
            }
        ]
    },
    {
        "description": "strict-tree schema, guards against misspelled properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/strict-tree.json",
            "$dynamicAnchor": "node",

            "$ref": "tree.json",
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "instance with misspelled field",
                "data": {
                    "children": [{
                            "daat": 1
                        }]
                },
                "valid": false
            },
            {
                "description": "instance with correct field",
                "data": {
                    "children": [{
                            "data": 1
                        }]
                },
                "valid": true
            }
        ]
    },
    {
        "description": "tests for implementation dynamic anchor and reference link",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/strict-extendible.json",
            "$ref": "extendible-dynamic-ref.json",
            "$defs": {
                "elements": {
                    "$dynamicAnchor": "elements",
                    "properties": {
                        "a": true
                    },
                    "required": ["a"],
                    "additionalProperties": false
                }
            }
        },
        "tests": [
            {
                "description": "incorrect parent schema",
                "data": {
                    "a": true
                },
                "valid": false
            },
            {
                "description": "incorrect extended schema",
                "data": {
                    "elements": [
                        { "b": 1 }
                    ]
                },
                "valid": false
            },
            {
                "description": "correct extended schema",
                "data": {
                    "elements": [
                        { "a": 1 }
                    ]
                },
                "valid": true
            }
        ]
    },
    {
        "description": "$ref and $dynamicAnchor are independent of order - $defs first",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/strict-extendible-allof-defs-first.json",
            "allOf": [
                {
                    "$ref": "extendible-dynamic-ref.json"
                },
                {
                    "$defs": {
                        "elements": {
                            "$dynamicAnchor": "elements",
                            "properties": {
                                "a": true
                            },
                            "required": ["a"],
                            "additionalProperties": false
                        }
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "incorrect parent schema",
                "data": {
                    "a": true
                },
                "valid": false
            },
            {
                "description": "incorrect extended schema",
                "data": {
                    "elements": [
                        { "b": 1 }
                    ]
                },
                "valid": false
            },
            {
                "description": "correct extended schema",
                "data": {
                    "elements": [
                        { "a": 1 }
                    ]
                },
                "valid": true
            }
        ]
    },
    {
        "description": "$ref and $dynamicAnchor are independent of order - $ref first",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/strict-extendible-allof-ref-first.json",
            "allOf": [
                {
                    "$defs": {
                        "elements": {
                            "$dynamicAnchor": "elements",
                            "properties": {
                                "a": true
                            },
                            "required": ["a"],
                            "additionalProperties": false
                        }
                    }
                },
                {
                    "$ref": "extendible-dynamic-ref.json"
                }
            ]
        },
        "tests": [
            {
                "description": "incorrect parent schema",
                "data": {
                    "a": true
                },
                "valid": false
            },
            {
                "description": "incorrect extended schema",
                "data": {
                    "elements": [
                        { "b": 1 }
                    ]
                },
                "valid": false
            },
            {
                "description": "correct extended schema",
                "data": {
                    "elements": [
                        { "a": 1 }
                    ]
                },
                "valid": true
            }
        ]
    },
    {
        "description": "$ref to $dynamicRef finds detached $dynamicAnchor",
        "schema": {
            "$ref": "http://localhost:1234/draft2020-12/detached-dynamicref.json#/$defs/foo"
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "$dynamicRef points to a boolean schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "true": true,
                "false": false
            },
            "properties": {
                "true": {
                    "$dynamicRef": "#/$defs/true"
                },
                "false": {
                    "$dynamicRef": "#/$defs/false"
                }
            }
        },
        "tests": [
            {
                "description": "follow $dynamicRef to a true schema",
                "data": { "true": 1 },
                "valid": true
            },
            {
                "description": "follow $dynamicRef to a false schema",
                "data": { "false": 1 },
                "valid": false
            }
        ]
    },
    {
        "description": "$dynamicRef skips over intermediate resources - direct reference",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://test.json-schema.org/dynamic-ref-skips-intermediate-resource/main",
            "type": "object",
            "properties": {
                "bar-item": {
                    "$ref": "item"
                }
            },
            "$defs": {
                "bar": {
                    "$id": "bar",
                    "type": "array",
                    "items": {
                        "$ref": "item"
                    },
                    "$defs": {
                        "item": {
                            "$id": "item",
                            "type": "object",
                            "properties": {
                                "content": {
                                    "$dynamicRef": "#content"
                                }
                            },
                            "$defs": {
                                "defaultContent": {
                                    "$dynamicAnchor": "content",
                                    "type": "integer"
                                }
                            }
                        },
                        "content": {
                            "$dynamicAnchor": "content",
                            "type": "string"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "integer property passes",
                "data": { "bar-item": { "content": 42 } },
                "valid": true
            },
            {
                "description": "string property fails",
                "data": { "bar-item": { "content": "value" } },
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/enum.json
================================================
[
    {
        "description": "simple enum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [1, 2, 3]
        },
        "tests": [
            {
                "description": "one of the enum is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "something else is invalid",
                "data": 4,
                "valid": false
            }
        ]
    },
    {
        "description": "heterogeneous enum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [6, "foo", [], true, {"foo": 12}]
        },
        "tests": [
            {
                "description": "one of the enum is valid",
                "data": [],
                "valid": true
            },
            {
                "description": "something else is invalid",
                "data": null,
                "valid": false
            },
            {
                "description": "objects are deep compared",
                "data": {"foo": false},
                "valid": false
            },
            {
                "description": "valid object matches",
                "data": {"foo": 12},
                "valid": true
            },
            {
                "description": "extra properties in object is invalid",
                "data": {"foo": 12, "boo": 42},
                "valid": false
            }
        ]
    },
    {
        "description": "heterogeneous enum-with-null validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [6, null]
        },
        "tests": [
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "number is valid",
                "data": 6,
                "valid": true
            },
            {
                "description": "something else is invalid",
                "data": "test",
                "valid": false
            }
        ]
    },
    {
        "description": "enums in properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type":"object",
            "properties": {
                "foo": {"enum":["foo"]},
                "bar": {"enum":["bar"]}
            },
            "required": ["bar"]
        },
        "tests": [
            {
                "description": "both properties are valid",
                "data": {"foo":"foo", "bar":"bar"},
                "valid": true
            },
            {
                "description": "wrong foo value",
                "data": {"foo":"foot", "bar":"bar"},
                "valid": false
            },
            {
                "description": "wrong bar value",
                "data": {"foo":"foo", "bar":"bart"},
                "valid": false
            },
            {
                "description": "missing optional property is valid",
                "data": {"bar":"bar"},
                "valid": true
            },
            {
                "description": "missing required property is invalid",
                "data": {"foo":"foo"},
                "valid": false
            },
            {
                "description": "missing all properties is invalid",
                "data": {},
                "valid": false
            }
        ]
    },
    {
        "description": "enum with escaped characters",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": ["foo\nbar", "foo\rbar"]
        },
        "tests": [
            {
                "description": "member 1 is valid",
                "data": "foo\nbar",
                "valid": true
            },
            {
                "description": "member 2 is valid",
                "data": "foo\rbar",
                "valid": true
            },
            {
                "description": "another string is invalid",
                "data": "abc",
                "valid": false
            }
        ]
    },
    {
        "description": "enum with false does not match 0",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [false]
        },
        "tests": [
            {
                "description": "false is valid",
                "data": false,
                "valid": true
            },
            {
                "description": "integer zero is invalid",
                "data": 0,
                "valid": false
            },
            {
                "description": "float zero is invalid",
                "data": 0.0,
                "valid": false
            }
        ]
    },
    {
        "description": "enum with [false] does not match [0]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [[false]]
        },
        "tests": [
            {
                "description": "[false] is valid",
                "data": [false],
                "valid": true
            },
            {
                "description": "[0] is invalid",
                "data": [0],
                "valid": false
            },
            {
                "description": "[0.0] is invalid",
                "data": [0.0],
                "valid": false
            }
        ]
    },
    {
        "description": "enum with true does not match 1",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [true]
        },
        "tests": [
            {
                "description": "true is valid",
                "data": true,
                "valid": true
            },
            {
                "description": "integer one is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "float one is invalid",
                "data": 1.0,
                "valid": false
            }
        ]
    },
    {
        "description": "enum with [true] does not match [1]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [[true]]
        },
        "tests": [
            {
                "description": "[true] is valid",
                "data": [true],
                "valid": true
            },
            {
                "description": "[1] is invalid",
                "data": [1],
                "valid": false
            },
            {
                "description": "[1.0] is invalid",
                "data": [1.0],
                "valid": false
            }
        ]
    },
    {
        "description": "enum with 0 does not match false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [0]
        },
        "tests": [
            {
                "description": "false is invalid",
                "data": false,
                "valid": false
            },
            {
                "description": "integer zero is valid",
                "data": 0,
                "valid": true
            },
            {
                "description": "float zero is valid",
                "data": 0.0,
                "valid": true
            }
        ]
    },
    {
        "description": "enum with [0] does not match [false]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [[0]]
        },
        "tests": [
            {
                "description": "[false] is invalid",
                "data": [false],
                "valid": false
            },
            {
                "description": "[0] is valid",
                "data": [0],
                "valid": true
            },
            {
                "description": "[0.0] is valid",
                "data": [0.0],
                "valid": true
            }
        ]
    },
    {
        "description": "enum with 1 does not match true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [1]
        },
        "tests": [
            {
                "description": "true is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "integer one is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "float one is valid",
                "data": 1.0,
                "valid": true
            }
        ]
    },
    {
        "description": "enum with [1] does not match [true]",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [[1]]
        },
        "tests": [
            {
                "description": "[true] is invalid",
                "data": [true],
                "valid": false
            },
            {
                "description": "[1] is valid",
                "data": [1],
                "valid": true
            },
            {
                "description": "[1.0] is valid",
                "data": [1.0],
                "valid": true
            }
        ]
    },
    {
        "description": "nul characters in strings",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "enum": [ "hello\u0000there" ]
        },
        "tests": [
            {
                "description": "match string with nul",
                "data": "hello\u0000there",
                "valid": true
            },
            {
                "description": "do not match string lacking nul",
                "data": "hellothere",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/exclusiveMaximum.json
================================================
[
    {
        "description": "exclusiveMaximum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "exclusiveMaximum": 3.0
        },
        "tests": [
            {
                "description": "below the exclusiveMaximum is valid",
                "data": 2.2,
                "valid": true
            },
            {
                "description": "boundary point is invalid",
                "data": 3.0,
                "valid": false
            },
            {
                "description": "above the exclusiveMaximum is invalid",
                "data": 3.5,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "x",
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/exclusiveMinimum.json
================================================
[
    {
        "description": "exclusiveMinimum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "exclusiveMinimum": 1.1
        },
        "tests": [
            {
                "description": "above the exclusiveMinimum is valid",
                "data": 1.2,
                "valid": true
            },
            {
                "description": "boundary point is invalid",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "below the exclusiveMinimum is invalid",
                "data": 0.6,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "x",
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/if-then-else.json
================================================
[
    {
        "description": "ignore if without then or else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "const": 0
            }
        },
        "tests": [
            {
                "description": "valid when valid against lone if",
                "data": 0,
                "valid": true
            },
            {
                "description": "valid when invalid against lone if",
                "data": "hello",
                "valid": true
            }
        ]
    },
    {
        "description": "ignore then without if",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "then": {
                "const": 0
            }
        },
        "tests": [
            {
                "description": "valid when valid against lone then",
                "data": 0,
                "valid": true
            },
            {
                "description": "valid when invalid against lone then",
                "data": "hello",
                "valid": true
            }
        ]
    },
    {
        "description": "ignore else without if",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "else": {
                "const": 0
            }
        },
        "tests": [
            {
                "description": "valid when valid against lone else",
                "data": 0,
                "valid": true
            },
            {
                "description": "valid when invalid against lone else",
                "data": "hello",
                "valid": true
            }
        ]
    },
    {
        "description": "if and then without else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "exclusiveMaximum": 0
            },
            "then": {
                "minimum": -10
            }
        },
        "tests": [
            {
                "description": "valid through then",
                "data": -1,
                "valid": true
            },
            {
                "description": "invalid through then",
                "data": -100,
                "valid": false
            },
            {
                "description": "valid when if test fails",
                "data": 3,
                "valid": true
            }
        ]
    },
    {
        "description": "if and else without then",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "exclusiveMaximum": 0
            },
            "else": {
                "multipleOf": 2
            }
        },
        "tests": [
            {
                "description": "valid when if test passes",
                "data": -1,
                "valid": true
            },
            {
                "description": "valid through else",
                "data": 4,
                "valid": true
            },
            {
                "description": "invalid through else",
                "data": 3,
                "valid": false
            }
        ]
    },
    {
        "description": "validate against correct branch, then vs else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "exclusiveMaximum": 0
            },
            "then": {
                "minimum": -10
            },
            "else": {
                "multipleOf": 2
            }
        },
        "tests": [
            {
                "description": "valid through then",
                "data": -1,
                "valid": true
            },
            {
                "description": "invalid through then",
                "data": -100,
                "valid": false
            },
            {
                "description": "valid through else",
                "data": 4,
                "valid": true
            },
            {
                "description": "invalid through else",
                "data": 3,
                "valid": false
            }
        ]
    },
    {
        "description": "non-interference across combined schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "if": {
                        "exclusiveMaximum": 0
                    }
                },
                {
                    "then": {
                        "minimum": -10
                    }
                },
                {
                    "else": {
                        "multipleOf": 2
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "valid, but would have been invalid through then",
                "data": -100,
                "valid": true
            },
            {
                "description": "valid, but would have been invalid through else",
                "data": 3,
                "valid": true
            }
        ]
    },
    {
        "description": "if with boolean schema true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": true,
            "then": { "const": "then" },
            "else": { "const": "else" }
        },
        "tests": [
            {
                "description": "boolean schema true in if always chooses the then path (valid)",
                "data": "then",
                "valid": true
            },
            {
                "description": "boolean schema true in if always chooses the then path (invalid)",
                "data": "else",
                "valid": false
            }
        ]
    },
    {
        "description": "if with boolean schema false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": false,
            "then": { "const": "then" },
            "else": { "const": "else" }
        },
        "tests": [
            {
                "description": "boolean schema false in if always chooses the else path (invalid)",
                "data": "then",
                "valid": false
            },
            {
                "description": "boolean schema false in if always chooses the else path (valid)",
                "data": "else",
                "valid": true
            }
        ]
    },
    {
        "description": "if appears at the end when serialized (keyword processing sequence)",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "then": { "const": "yes" },
            "else": { "const": "other" },
            "if": { "maxLength": 4 }
        },
        "tests": [
            {
                "description": "yes redirects to then and passes",
                "data": "yes",
                "valid": true
            },
            {
                "description": "other redirects to else and passes",
                "data": "other",
                "valid": true
            },
            {
                "description": "no redirects to then and fails",
                "data": "no",
                "valid": false
            },
            {
                "description": "invalid redirects to else and fails",
                "data": "invalid",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/infinite-loop-detection.json
================================================
[
    {
        "description": "evaluating the same schema location against the same data location twice is not a sign of an infinite loop",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "int": { "type": "integer" }
            },
            "allOf": [
                {
                    "properties": {
                        "foo": {
                            "$ref": "#/$defs/int"
                        }
                    }
                },
                {
                    "additionalProperties": {
                        "$ref": "#/$defs/int"
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "passing case",
                "data": { "foo": 1 },
                "valid": true
            },
            {
                "description": "failing case",
                "data": { "foo": "a string" },
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/items.json
================================================
[
    {
        "description": "a schema given for items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": {"type": "integer"}
        },
        "tests": [
            {
                "description": "valid items",
                "data": [ 1, 2, 3 ],
                "valid": true
            },
            {
                "description": "wrong type of items",
                "data": [1, "x"],
                "valid": false
            },
            {
                "description": "ignores non-arrays",
                "data": {"foo" : "bar"},
                "valid": true
            },
            {
                "description": "JavaScript pseudo-array is valid",
                "data": {
                    "0": "invalid",
                    "length": 1
                },
                "valid": true
            }
        ]
    },
    {
        "description": "items with boolean schema (true)",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": true
        },
        "tests": [
            {
                "description": "any array is valid",
                "data": [ 1, "foo", true ],
                "valid": true
            },
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "items with boolean schema (false)",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": false
        },
        "tests": [
            {
                "description": "any non-empty array is invalid",
                "data": [ 1, "foo", true ],
                "valid": false
            },
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "items and subitems",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "item": {
                    "type": "array",
                    "items": false,
                    "prefixItems": [
                        { "$ref": "#/$defs/sub-item" },
                        { "$ref": "#/$defs/sub-item" }
                    ]
                },
                "sub-item": {
                    "type": "object",
                    "required": ["foo"]
                }
            },
            "type": "array",
            "items": false,
            "prefixItems": [
                { "$ref": "#/$defs/item" },
                { "$ref": "#/$defs/item" },
                { "$ref": "#/$defs/item" }
            ]
        },
        "tests": [
            {
                "description": "valid items",
                "data": [
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ]
                ],
                "valid": true
            },
            {
                "description": "too many items",
                "data": [
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ]
                ],
                "valid": false
            },
            {
                "description": "too many sub-items",
                "data": [
                    [ {"foo": null}, {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ]
                ],
                "valid": false
            },
            {
                "description": "wrong item",
                "data": [
                    {"foo": null},
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ]
                ],
                "valid": false
            },
            {
                "description": "wrong sub-item",
                "data": [
                    [ {}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ],
                    [ {"foo": null}, {"foo": null} ]
                ],
                "valid": false
            },
            {
                "description": "fewer items is valid",
                "data": [
                    [ {"foo": null} ],
                    [ {"foo": null} ]
                ],
                "valid": true
            }
        ]
    },
    {
        "description": "nested items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "array",
            "items": {
                "type": "array",
                "items": {
                    "type": "array",
                    "items": {
                        "type": "array",
                        "items": {
                            "type": "number"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "valid nested array",
                "data": [[[[1]], [[2],[3]]], [[[4], [5], [6]]]],
                "valid": true
            },
            {
                "description": "nested array with invalid type",
                "data": [[[["1"]], [[2],[3]]], [[[4], [5], [6]]]],
                "valid": false
            },
            {
                "description": "not deep enough",
                "data": [[[1], [2],[3]], [[4], [5], [6]]],
                "valid": false
            }
        ]
    },
    {
        "description": "prefixItems with no additional items allowed",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{}, {}, {}],
            "items": false
        },
        "tests": [
            {
                "description": "empty array",
                "data": [ ],
                "valid": true
            },
            {
                "description": "fewer number of items present (1)",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "fewer number of items present (2)",
                "data": [ 1, 2 ],
                "valid": true
            },
            {
                "description": "equal number of items present",
                "data": [ 1, 2, 3 ],
                "valid": true
            },
            {
                "description": "additional items are not permitted",
                "data": [ 1, 2, 3, 4 ],
                "valid": false
            }
        ]
    },
    {
        "description": "items does not look in applicators, valid case",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                { "prefixItems": [ { "minimum": 3 } ] }
            ],
            "items": { "minimum": 5 }
        },
        "tests": [
            {
                "description": "prefixItems in allOf does not constrain items, invalid case",
                "data": [ 3, 5 ],
                "valid": false
            },
            {
                "description": "prefixItems in allOf does not constrain items, valid case",
                "data": [ 5, 5 ],
                "valid": true
            }
        ]
    },
    {
        "description": "prefixItems validation adjusts the starting index for items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [ { "type": "string" } ],
            "items": { "type": "integer" }
        },
        "tests": [
            {
                "description": "valid items",
                "data": [ "x", 2, 3 ],
                "valid": true
            },
            {
                "description": "wrong type of second item",
                "data": [ "x", "y" ],
                "valid": false
            }
        ]
    },
    {
        "description": "items with heterogeneous array",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{}],
            "items": false
        },
        "tests": [
            {
                "description": "heterogeneous invalid instance",
                "data": [ "foo", "bar", 37 ],
                "valid": false
            },
            {
                "description": "valid instance",
                "data": [ null ],
                "valid": true
            }
        ]
    },
    {
        "description": "items with null instance elements",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": {
                "type": "null"
            }
        },
        "tests": [
            {
                "description": "allows null elements",
                "data": [ null ],
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/maxContains.json
================================================
[
    {
        "description": "maxContains without contains is ignored",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxContains": 1
        },
        "tests": [
            {
                "description": "one item valid against lone maxContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "two items still valid against lone maxContains",
                "data": [ 1, 2 ],
                "valid": true
            }
        ]
    },
    {
        "description": "maxContains with contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "maxContains": 1
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": false
            },
            {
                "description": "all elements match, valid maxContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "all elements match, invalid maxContains",
                "data": [ 1, 1 ],
                "valid": false
            },
            {
                "description": "some elements match, valid maxContains",
                "data": [ 1, 2 ],
                "valid": true
            },
            {
                "description": "some elements match, invalid maxContains",
                "data": [ 1, 2, 1 ],
                "valid": false
            }
        ]
    },
    {
        "description": "maxContains with contains, value with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "maxContains": 1.0
        },
        "tests": [
            {
                "description": "one element matches, valid maxContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "too many elements match, invalid maxContains",
                "data": [ 1, 1 ],
                "valid": false
            }
        ]
    },
    {
        "description": "minContains < maxContains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 1,
            "maxContains": 3
        },
        "tests": [
            {
                "description": "actual < minContains < maxContains",
                "data": [ ],
                "valid": false
            },
            {
                "description": "minContains < actual < maxContains",
                "data": [ 1, 1 ],
                "valid": true
            },
            {
                "description": "minContains < maxContains < actual",
                "data": [ 1, 1, 1, 1 ],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/maxItems.json
================================================
[
    {
        "description": "maxItems validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxItems": 2
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": [1],
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": [1, 2, 3],
                "valid": false
            },
            {
                "description": "ignores non-arrays",
                "data": "foobar",
                "valid": true
            }
        ]
    },
    {
        "description": "maxItems validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxItems": 2.0
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": [1],
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": [1, 2, 3],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/maxLength.json
================================================
[
    {
        "description": "maxLength validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxLength": 2
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": "f",
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": "fo",
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": "foo",
                "valid": false
            },
            {
                "description": "ignores non-strings",
                "data": 100,
                "valid": true
            },
            {
                "description": "two graphemes is long enough",
                "data": "\uD83D\uDCA9\uD83D\uDCA9",
                "valid": true
            }
        ]
    },
    {
        "description": "maxLength validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxLength": 2.0
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": "f",
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/maxProperties.json
================================================
[
    {
        "description": "maxProperties validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxProperties": 2
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": {"foo": 1, "bar": 2, "baz": 3},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": [1, 2, 3],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "maxProperties validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxProperties": 2.0
        },
        "tests": [
            {
                "description": "shorter is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "too long is invalid",
                "data": {"foo": 1, "bar": 2, "baz": 3},
                "valid": false
            }
        ]
    },
    {
        "description": "maxProperties = 0 means the object is empty",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maxProperties": 0
        },
        "tests": [
            {
                "description": "no properties is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "one property is invalid",
                "data": { "foo": 1 },
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/maximum.json
================================================
[
    {
        "description": "maximum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maximum": 3.0
        },
        "tests": [
            {
                "description": "below the maximum is valid",
                "data": 2.6,
                "valid": true
            },
            {
                "description": "boundary point is valid",
                "data": 3.0,
                "valid": true
            },
            {
                "description": "above the maximum is invalid",
                "data": 3.5,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "x",
                "valid": true
            }
        ]
    },
    {
        "description": "maximum validation with unsigned integer",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "maximum": 300
        },
        "tests":  [
            {
                "description": "below the maximum is invalid",
                "data": 299.97,
                "valid": true
            },
            {
                "description": "boundary point integer is valid",
                "data": 300,
                "valid": true
            },
            {
                "description": "boundary point float is valid",
                "data": 300.00,
                "valid": true
            },
            {
                "description": "above the maximum is invalid",
                "data": 300.5,
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/minContains.json
================================================
[
    {
        "description": "minContains without contains is ignored",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minContains": 1
        },
        "tests": [
            {
                "description": "one item valid against lone minContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "zero items still valid against lone minContains",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "minContains=1 with contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 1
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": false
            },
            {
                "description": "no elements match",
                "data": [ 2 ],
                "valid": false
            },
            {
                "description": "single element matches, valid minContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "some elements match, valid minContains",
                "data": [ 1, 2 ],
                "valid": true
            },
            {
                "description": "all elements match, valid minContains",
                "data": [ 1, 1 ],
                "valid": true
            }
        ]
    },
    {
        "description": "minContains=2 with contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 2
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": false
            },
            {
                "description": "all elements match, invalid minContains",
                "data": [ 1 ],
                "valid": false
            },
            {
                "description": "some elements match, invalid minContains",
                "data": [ 1, 2 ],
                "valid": false
            },
            {
                "description": "all elements match, valid minContains (exactly as needed)",
                "data": [ 1, 1 ],
                "valid": true
            },
            {
                "description": "all elements match, valid minContains (more than needed)",
                "data": [ 1, 1, 1 ],
                "valid": true
            },
            {
                "description": "some elements match, valid minContains",
                "data": [ 1, 2, 1 ],
                "valid": true
            }
        ]
    },
    {
        "description": "minContains=2 with contains with a decimal value",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 2.0
        },
        "tests": [
            {
                "description": "one element matches, invalid minContains",
                "data": [ 1 ],
                "valid": false
            },
            {
                "description": "both elements match, valid minContains",
                "data": [ 1, 1 ],
                "valid": true
            }
        ]
    },
    {
        "description": "maxContains = minContains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "maxContains": 2,
            "minContains": 2
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": false
            },
            {
                "description": "all elements match, invalid minContains",
                "data": [ 1 ],
                "valid": false
            },
            {
                "description": "all elements match, invalid maxContains",
                "data": [ 1, 1, 1 ],
                "valid": false
            },
            {
                "description": "all elements match, valid maxContains and minContains",
                "data": [ 1, 1 ],
                "valid": true
            }
        ]
    },
    {
        "description": "maxContains < minContains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "maxContains": 1,
            "minContains": 3
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": false
            },
            {
                "description": "invalid minContains",
                "data": [ 1 ],
                "valid": false
            },
            {
                "description": "invalid maxContains",
                "data": [ 1, 1, 1 ],
                "valid": false
            },
            {
                "description": "invalid maxContains and minContains",
                "data": [ 1, 1 ],
                "valid": false
            }
        ]
    },
    {
        "description": "minContains = 0",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 0
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": true
            },
            {
                "description": "minContains = 0 makes contains always pass",
                "data": [ 2 ],
                "valid": true
            }
        ]
    },
    {
        "description": "minContains = 0 with maxContains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "contains": {"const": 1},
            "minContains": 0,
            "maxContains": 1
        },
        "tests": [
            {
                "description": "empty data",
                "data": [ ],
                "valid": true
            },
            {
                "description": "not more than maxContains",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "too many",
                "data": [ 1, 1 ],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/minItems.json
================================================
[
    {
        "description": "minItems validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minItems": 1
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": [1],
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": [],
                "valid": false
            },
            {
                "description": "ignores non-arrays",
                "data": "",
                "valid": true
            }
        ]
    },
    {
        "description": "minItems validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minItems": 1.0
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": [],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/minLength.json
================================================
[
    {
        "description": "minLength validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minLength": 2
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": "fo",
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": "f",
                "valid": false
            },
            {
                "description": "ignores non-strings",
                "data": 1,
                "valid": true
            },
            {
                "description": "one grapheme is not long enough",
                "data": "\uD83D\uDCA9",
                "valid": false
            }
        ]
    },
    {
        "description": "minLength validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minLength": 2.0
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": "f",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/minProperties.json
================================================
[
    {
        "description": "minProperties validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minProperties": 1
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "exact length is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "minProperties validation with a decimal",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minProperties": 1.0
        },
        "tests": [
            {
                "description": "longer is valid",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "too short is invalid",
                "data": {},
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/minimum.json
================================================
[
    {
        "description": "minimum validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minimum": 1.1
        },
        "tests": [
            {
                "description": "above the minimum is valid",
                "data": 2.6,
                "valid": true
            },
            {
                "description": "boundary point is valid",
                "data": 1.1,
                "valid": true
            },
            {
                "description": "below the minimum is invalid",
                "data": 0.6,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "x",
                "valid": true
            }
        ]
    },
    {
        "description": "minimum validation with signed integer",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "minimum": -2
        },
        "tests": [
            {
                "description": "negative above the minimum is valid",
                "data": -1,
                "valid": true
            },
            {
                "description": "positive above the minimum is valid",
                "data": 0,
                "valid": true
            },
            {
                "description": "boundary point is valid",
                "data": -2,
                "valid": true
            },
            {
                "description": "boundary point with float is valid",
                "data": -2.0,
                "valid": true
            },
            {
                "description": "float below the minimum is invalid",
                "data": -2.0001,
                "valid": false
            },
            {
                "description": "int below the minimum is invalid",
                "data": -3,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "x",
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/multipleOf.json
================================================
[
    {
        "description": "by int",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "multipleOf": 2
        },
        "tests": [
            {
                "description": "int by int",
                "data": 10,
                "valid": true
            },
            {
                "description": "int by int fail",
                "data": 7,
                "valid": false
            },
            {
                "description": "ignores non-numbers",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "by number",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "multipleOf": 1.5
        },
        "tests": [
            {
                "description": "zero is multiple of anything",
                "data": 0,
                "valid": true
            },
            {
                "description": "4.5 is multiple of 1.5",
                "data": 4.5,
                "valid": true
            },
            {
                "description": "35 is not multiple of 1.5",
                "data": 35,
                "valid": false
            }
        ]
    },
    {
        "description": "by small number",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "multipleOf": 0.0001
        },
        "tests": [
            {
                "description": "0.0075 is multiple of 0.0001",
                "data": 0.0075,
                "valid": true
            },
            {
                "description": "0.00751 is not multiple of 0.0001",
                "data": 0.00751,
                "valid": false
            }
        ]
    },
    {
        "description": "float division = inf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "integer", "multipleOf": 0.123456789
        },
        "tests": [
            {
                "description": "always invalid, but naive implementations may raise an overflow error",
                "data": 1e308,
                "valid": false
            }
        ]
    },
    {
        "description": "small multiple of large integer",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "integer", "multipleOf": 1e-8
        },
        "tests": [
            {
                "description": "any integer is a multiple of 1e-8",
                "data": 12391239123,
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/not.json
================================================
[
    {
        "description": "not",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": {"type": "integer"}
        },
        "tests": [
            {
                "description": "allowed",
                "data": "foo",
                "valid": true
            },
            {
                "description": "disallowed",
                "data": 1,
                "valid": false
            }
        ]
    },
    {
        "description": "not multiple types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": {"type": ["integer", "boolean"]}
        },
        "tests": [
            {
                "description": "valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "mismatch",
                "data": 1,
                "valid": false
            },
            {
                "description": "other mismatch",
                "data": true,
                "valid": false
            }
        ]
    },
    {
        "description": "not more complex schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": {
                "type": "object",
                "properties": {
                    "foo": {
                        "type": "string"
                    }
                }
             }
        },
        "tests": [
            {
                "description": "match",
                "data": 1,
                "valid": true
            },
            {
                "description": "other match",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "mismatch",
                "data": {"foo": "bar"},
                "valid": false
            }
        ]
    },
    {
        "description": "forbidden property",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {
                    "not": {}
                }
            }
        },
        "tests": [
            {
                "description": "property present",
                "data": {"foo": 1, "bar": 2},
                "valid": false
            },
            {
                "description": "property absent",
                "data": {"bar": 1, "baz": 2},
                "valid": true
            }
        ]
    },
    {
        "description": "forbid everything with empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": {}
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            },
            {
                "description": "boolean true is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "boolean false is invalid",
                "data": false,
                "valid": false
            },
            {
                "description": "null is invalid",
                "data": null,
                "valid": false
            },
            {
                "description": "object is invalid",
                "data": {"foo": "bar"},
                "valid": false
            },
            {
                "description": "empty object is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "array is invalid",
                "data": ["foo"],
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            }
        ]
    },
    {
        "description": "forbid everything with boolean schema true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": true
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            },
            {
                "description": "boolean true is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "boolean false is invalid",
                "data": false,
                "valid": false
            },
            {
                "description": "null is invalid",
                "data": null,
                "valid": false
            },
            {
                "description": "object is invalid",
                "data": {"foo": "bar"},
                "valid": false
            },
            {
                "description": "empty object is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "array is invalid",
                "data": ["foo"],
                "valid": false
            },
            {
                "description": "empty array is invalid",
                "data": [],
                "valid": false
            }
        ]
    },
    {
        "description": "allow everything with boolean schema false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": false
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "boolean true is valid",
                "data": true,
                "valid": true
            },
            {
                "description": "boolean false is valid",
                "data": false,
                "valid": true
            },
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "object is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "array is valid",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "double negation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": { "not": {} }
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "collect annotations inside a 'not', even if collection is disabled",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "not": {
                "$comment": "this subschema must still produce annotations internally, even though the 'not' will ultimately discard them",
                "anyOf": [
                    true,
                    { "properties": { "foo": true } }
                ],
                "unevaluatedProperties": false
            }
        },
        "tests": [
            {
                "description": "unevaluated property",
                "data": { "bar": 1 },
                "valid": true
            },
            {
                "description": "annotations are still collected inside a 'not'",
                "data": { "foo": 1 },
                "valid": false
            }
        ]
     }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/oneOf.json
================================================
[
    {
        "description": "oneOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [
                {
                    "type": "integer"
                },
                {
                    "minimum": 2
                }
            ]
        },
        "tests": [
            {
                "description": "first oneOf valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "second oneOf valid",
                "data": 2.5,
                "valid": true
            },
            {
                "description": "both oneOf valid",
                "data": 3,
                "valid": false
            },
            {
                "description": "neither oneOf valid",
                "data": 1.5,
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with base schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "string",
            "oneOf" : [
                {
                    "minLength": 2
                },
                {
                    "maxLength": 4
                }
            ]
        },
        "tests": [
            {
                "description": "mismatch base schema",
                "data": 3,
                "valid": false
            },
            {
                "description": "one oneOf valid",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "both oneOf valid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with boolean schemas, all true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [true, true, true]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with boolean schemas, one true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [true, false, false]
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "oneOf with boolean schemas, more than one true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [true, true, false]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with boolean schemas, all false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [false, false, false]
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf complex types",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [
                {
                    "properties": {
                        "bar": {"type": "integer"}
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "foo": {"type": "string"}
                    },
                    "required": ["foo"]
                }
            ]
        },
        "tests": [
            {
                "description": "first oneOf valid (complex)",
                "data": {"bar": 2},
                "valid": true
            },
            {
                "description": "second oneOf valid (complex)",
                "data": {"foo": "baz"},
                "valid": true
            },
            {
                "description": "both oneOf valid (complex)",
                "data": {"foo": "baz", "bar": 2},
                "valid": false
            },
            {
                "description": "neither oneOf valid (complex)",
                "data": {"foo": 2, "bar": "quux"},
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with empty schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [
                { "type": "number" },
                {}
            ]
        },
        "tests": [
            {
                "description": "one valid - valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "both valid - invalid",
                "data": 123,
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with required",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "oneOf": [
                { "required": ["foo", "bar"] },
                { "required": ["foo", "baz"] }
            ]
        },
        "tests": [
            {
                "description": "both invalid - invalid",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "first valid - valid",
                "data": {"foo": 1, "bar": 2},
                "valid": true
            },
            {
                "description": "second valid - valid",
                "data": {"foo": 1, "baz": 3},
                "valid": true
            },
            {
                "description": "both valid - invalid",
                "data": {"foo": 1, "bar": 2, "baz" : 3},
                "valid": false
            }
        ]
    },
    {
        "description": "oneOf with missing optional property",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [
                {
                    "properties": {
                        "bar": true,
                        "baz": true
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "foo": true
                    },
                    "required": ["foo"]
                }
            ]
        },
        "tests": [
            {
                "description": "first oneOf valid",
                "data": {"bar": 8},
                "valid": true
            },
            {
                "description": "second oneOf valid",
                "data": {"foo": "foo"},
                "valid": true
            },
            {
                "description": "both oneOf valid",
                "data": {"foo": "foo", "bar": 8},
                "valid": false
            },
            {
                "description": "neither oneOf valid",
                "data": {"baz": "quux"},
                "valid": false
            }
        ]
    },
    {
        "description": "nested oneOf, to check validation semantics",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "oneOf": [
                {
                    "oneOf": [
                        {
                            "type": "null"
                        }
                    ]
                }
            ]
        },
        "tests": [
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "anything non-null is invalid",
                "data": 123,
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/pattern.json
================================================
[
    {
        "description": "pattern validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "pattern": "^a*$"
        },
        "tests": [
            {
                "description": "a matching pattern is valid",
                "data": "aaa",
                "valid": true
            },
            {
                "description": "a non-matching pattern is invalid",
                "data": "abc",
                "valid": false
            },
            {
                "description": "ignores booleans",
                "data": true,
                "valid": true
            },
            {
                "description": "ignores integers",
                "data": 123,
                "valid": true
            },
            {
                "description": "ignores floats",
                "data": 1.0,
                "valid": true
            },
            {
                "description": "ignores objects",
                "data": {},
                "valid": true
            },
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores null",
                "data": null,
                "valid": true
            }
        ]
    },
    {
        "description": "pattern is not anchored",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "pattern": "a+"
        },
        "tests": [
            {
                "description": "matches a substring",
                "data": "xxaayy",
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/patternProperties.json
================================================
[
    {
        "description":
            "patternProperties validates properties matching a regex",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {
                "f.*o": {"type": "integer"}
            }
        },
        "tests": [
            {
                "description": "a single valid match is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "multiple valid matches is valid",
                "data": {"foo": 1, "foooooo" : 2},
                "valid": true
            },
            {
                "description": "a single invalid match is invalid",
                "data": {"foo": "bar", "fooooo": 2},
                "valid": false
            },
            {
                "description": "multiple invalid matches is invalid",
                "data": {"foo": "bar", "foooooo" : "baz"},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foo",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "multiple simultaneous patternProperties are validated",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {
                "a*": {"type": "integer"},
                "aaa*": {"maximum": 20}
            }
        },
        "tests": [
            {
                "description": "a single valid match is valid",
                "data": {"a": 21},
                "valid": true
            },
            {
                "description": "a simultaneous match is valid",
                "data": {"aaaa": 18},
                "valid": true
            },
            {
                "description": "multiple matches is valid",
                "data": {"a": 21, "aaaa": 18},
                "valid": true
            },
            {
                "description": "an invalid due to one is invalid",
                "data": {"a": "bar"},
                "valid": false
            },
            {
                "description": "an invalid due to the other is invalid",
                "data": {"aaaa": 31},
                "valid": false
            },
            {
                "description": "an invalid due to both is invalid",
                "data": {"aaa": "foo", "aaaa": 31},
                "valid": false
            }
        ]
    },
    {
        "description": "regexes are not anchored by default and are case sensitive",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {
                "[0-9]{2,}": { "type": "boolean" },
                "X_": { "type": "string" }
            }
        },
        "tests": [
            {
                "description": "non recognized members are ignored",
                "data": { "answer 1": "42" },
                "valid": true
            },
            {
                "description": "recognized members are accounted for",
                "data": { "a31b": null },
                "valid": false
            },
            {
                "description": "regexes are case sensitive",
                "data": { "a_x_3": 3 },
                "valid": true
            },
            {
                "description": "regexes are case sensitive, 2",
                "data": { "a_X_3": 3 },
                "valid": false
            }
        ]
    },
    {
        "description": "patternProperties with boolean schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {
                "f.*": true,
                "b.*": false
            }
        },
        "tests": [
            {
                "description": "object with property matching schema true is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "object with property matching schema false is invalid",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "object with both properties is invalid",
                "data": {"foo": 1, "bar": 2},
                "valid": false
            },
            {
                "description": "object with a property matching both true and false is invalid",
                "data": {"foobar":1},
                "valid": false
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "patternProperties with null valued instance properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "patternProperties": {
                "^.*bar$": {"type": "null"}
            }
        },
        "tests": [
            {
                "description": "allows null values",
                "data": {"foobar": null},
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/prefixItems.json
================================================
[
    {
        "description": "a schema given for prefixItems",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                {"type": "integer"},
                {"type": "string"}
            ]
        },
        "tests": [
            {
                "description": "correct types",
                "data": [ 1, "foo" ],
                "valid": true
            },
            {
                "description": "wrong types",
                "data": [ "foo", 1 ],
                "valid": false
            },
            {
                "description": "incomplete array of items",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "array with additional items",
                "data": [ 1, "foo", true ],
                "valid": true
            },
            {
                "description": "empty array",
                "data": [ ],
                "valid": true
            },
            {
                "description": "JavaScript pseudo-array is valid",
                "data": {
                    "0": "invalid",
                    "1": "valid",
                    "length": 2
                },
                "valid": true
            }
        ]
    },
    {
        "description": "prefixItems with boolean schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [true, false]
        },
        "tests": [
            {
                "description": "array with one item is valid",
                "data": [ 1 ],
                "valid": true
            },
            {
                "description": "array with two items is invalid",
                "data": [ 1, "foo" ],
                "valid": false
            },
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            }
        ]
    },
    {
        "description": "additional items are allowed by default",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{"type": "integer"}]
        },
        "tests": [
            {
                "description": "only the first item is validated",
                "data": [1, "foo", false],
                "valid": true
            }
        ]
    },
    {
        "description": "prefixItems with null instance elements",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                {
                    "type": "null"
                }
            ]
        },
        "tests": [
            {
                "description": "allows null elements",
                "data": [ null ],
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/properties.json
================================================
[
    {
        "description": "object properties validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {"type": "integer"},
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "both properties present and valid is valid",
                "data": {"foo": 1, "bar": "baz"},
                "valid": true
            },
            {
                "description": "one property invalid is invalid",
                "data": {"foo": 1, "bar": {}},
                "valid": false
            },
            {
                "description": "both properties invalid is invalid",
                "data": {"foo": [], "bar": {}},
                "valid": false
            },
            {
                "description": "doesn't invalidate other properties",
                "data": {"quux": []},
                "valid": true
            },
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description":
            "properties, patternProperties, additionalProperties interaction",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {"type": "array", "maxItems": 3},
                "bar": {"type": "array"}
            },
            "patternProperties": {"f.o": {"minItems": 2}},
            "additionalProperties": {"type": "integer"}
        },
        "tests": [
            {
                "description": "property validates property",
                "data": {"foo": [1, 2]},
                "valid": true
            },
            {
                "description": "property invalidates property",
                "data": {"foo": [1, 2, 3, 4]},
                "valid": false
            },
            {
                "description": "patternProperty invalidates property",
                "data": {"foo": []},
                "valid": false
            },
            {
                "description": "patternProperty validates nonproperty",
                "data": {"fxo": [1, 2]},
                "valid": true
            },
            {
                "description": "patternProperty invalidates nonproperty",
                "data": {"fxo": []},
                "valid": false
            },
            {
                "description": "additionalProperty ignores property",
                "data": {"bar": []},
                "valid": true
            },
            {
                "description": "additionalProperty validates others",
                "data": {"quux": 3},
                "valid": true
            },
            {
                "description": "additionalProperty invalidates others",
                "data": {"quux": "foo"},
                "valid": false
            }
        ]
    },
    {
        "description": "properties with boolean schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": true,
                "bar": false
            }
        },
        "tests": [
            {
                "description": "no property present is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "only 'true' property present is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "only 'false' property present is invalid",
                "data": {"bar": 2},
                "valid": false
            },
            {
                "description": "both properties present is invalid",
                "data": {"foo": 1, "bar": 2},
                "valid": false
            }
        ]
    },
    {
        "description": "properties with escaped characters",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo\nbar": {"type": "number"},
                "foo\"bar": {"type": "number"},
                "foo\\bar": {"type": "number"},
                "foo\rbar": {"type": "number"},
                "foo\tbar": {"type": "number"},
                "foo\fbar": {"type": "number"}
            }
        },
        "tests": [
            {
                "description": "object with all numbers is valid",
                "data": {
                    "foo\nbar": 1,
                    "foo\"bar": 1,
                    "foo\\bar": 1,
                    "foo\rbar": 1,
                    "foo\tbar": 1,
                    "foo\fbar": 1
                },
                "valid": true
            },
            {
                "description": "object with strings is invalid",
                "data": {
                    "foo\nbar": "1",
                    "foo\"bar": "1",
                    "foo\\bar": "1",
                    "foo\rbar": "1",
                    "foo\tbar": "1",
                    "foo\fbar": "1"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "properties with null valued instance properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {"type": "null"}
            }
        },
        "tests": [
            {
                "description": "allows null values",
                "data": {"foo": null},
                "valid": true
            }
        ]
    },
    {
        "description": "properties whose names are Javascript object property names",
        "comment": "Ensure JS implementations don't universally consider e.g. __proto__ to always be present in an object.",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "__proto__": {"type": "number"},
                "toString": {
                    "properties": { "length": { "type": "string" } }
                },
                "constructor": {"type": "number"}
            }
        },
        "tests": [
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            },
            {
                "description": "none of the properties mentioned",
                "data": {},
                "valid": true
            },
            {
                "description": "__proto__ not valid",
                "data": { "__proto__": "foo" },
                "valid": false
            },
            {
                "description": "toString not valid",
                "data": { "toString": { "length": 37 } },
                "valid": false
            },
            {
                "description": "constructor not valid",
                "data": { "constructor": { "length": 37 } },
                "valid": false
            },
            {
                "description": "all present and valid",
                "data": {
                    "__proto__": 12,
                    "toString": { "length": "foo" },
                    "constructor": 37
                },
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/propertyNames.json
================================================
[
    {
        "description": "propertyNames validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": {"maxLength": 3}
        },
        "tests": [
            {
                "description": "all property names valid",
                "data": {
                    "f": {},
                    "foo": {}
                },
                "valid": true
            },
            {
                "description": "some property names invalid",
                "data": {
                    "foo": {},
                    "foobar": {}
                },
                "valid": false
            },
            {
                "description": "object without properties is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "ignores arrays",
                "data": [1, 2, 3, 4],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foobar",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "propertyNames validation with pattern",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": { "pattern": "^a+$" }
        },
        "tests": [
            {
                "description": "matching property names valid",
                "data": {
                    "a": {},
                    "aa": {},
                    "aaa": {}
                },
                "valid": true
            },
            {
                "description": "non-matching property name is invalid",
                "data": {
                    "aaA": {}
                },
                "valid": false
            },
            {
                "description": "object without properties is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "propertyNames with boolean schema true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": true
        },
        "tests": [
            {
                "description": "object with any properties is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "propertyNames with boolean schema false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": false
        },
        "tests": [
            {
                "description": "object with any properties is invalid",
                "data": {"foo": 1},
                "valid": false
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "propertyNames with const",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": {"const": "foo"}
        },
        "tests": [
            {
                "description": "object with property foo is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "object with any other property is invalid",
                "data": {"bar": 1},
                "valid": false
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "propertyNames with enum",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": {"enum": ["foo", "bar"]}
        },
        "tests": [
            {
                "description": "object with property foo is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "object with property foo and bar is valid",
                "data": {"foo": 1, "bar": 1},
                "valid": true
            },
            {
                "description": "object with any other property is invalid",
                "data": {"baz": 1},
                "valid": false
            },
            {
                "description": "empty object is valid",
                "data": {},
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/ref.json
================================================
[
    {
        "description": "root pointer ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {"$ref": "#"}
            },
            "additionalProperties": false
        },
        "tests": [
            {
                "description": "match",
                "data": {"foo": false},
                "valid": true
            },
            {
                "description": "recursive match",
                "data": {"foo": {"foo": false}},
                "valid": true
            },
            {
                "description": "mismatch",
                "data": {"bar": false},
                "valid": false
            },
            {
                "description": "recursive mismatch",
                "data": {"foo": {"bar": false}},
                "valid": false
            }
        ]
    },
    {
        "description": "relative pointer ref to object",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {"type": "integer"},
                "bar": {"$ref": "#/properties/foo"}
            }
        },
        "tests": [
            {
                "description": "match",
                "data": {"bar": 3},
                "valid": true
            },
            {
                "description": "mismatch",
                "data": {"bar": true},
                "valid": false
            }
        ]
    },
    {
        "description": "relative pointer ref to array",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                {"type": "integer"},
                {"$ref": "#/prefixItems/0"}
            ]
        },
        "tests": [
            {
                "description": "match array",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "mismatch array",
                "data": [1, "foo"],
                "valid": false
            }
        ]
    },
    {
        "description": "escaped pointer ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "tilde~field": {"type": "integer"},
                "slash/field": {"type": "integer"},
                "percent%field": {"type": "integer"}
            },
            "properties": {
                "tilde": {"$ref": "#/$defs/tilde~0field"},
                "slash": {"$ref": "#/$defs/slash~1field"},
                "percent": {"$ref": "#/$defs/percent%25field"}
            }
        },
        "tests": [
            {
                "description": "slash invalid",
                "data": {"slash": "aoeu"},
                "valid": false
            },
            {
                "description": "tilde invalid",
                "data": {"tilde": "aoeu"},
                "valid": false
            },
            {
                "description": "percent invalid",
                "data": {"percent": "aoeu"},
                "valid": false
            },
            {
                "description": "slash valid",
                "data": {"slash": 123},
                "valid": true
            },
            {
                "description": "tilde valid",
                "data": {"tilde": 123},
                "valid": true
            },
            {
                "description": "percent valid",
                "data": {"percent": 123},
                "valid": true
            }
        ]
    },
    {
        "description": "nested refs",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "a": {"type": "integer"},
                "b": {"$ref": "#/$defs/a"},
                "c": {"$ref": "#/$defs/b"}
            },
            "$ref": "#/$defs/c"
        },
        "tests": [
            {
                "description": "nested ref valid",
                "data": 5,
                "valid": true
            },
            {
                "description": "nested ref invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "ref applies alongside sibling keywords",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "reffed": {
                    "type": "array"
                }
            },
            "properties": {
                "foo": {
                    "$ref": "#/$defs/reffed",
                    "maxItems": 2
                }
            }
        },
        "tests": [
            {
                "description": "ref valid, maxItems valid",
                "data": { "foo": [] },
                "valid": true
            },
            {
                "description": "ref valid, maxItems invalid",
                "data": { "foo": [1, 2, 3] },
                "valid": false
            },
            {
                "description": "ref invalid",
                "data": { "foo": "string" },
                "valid": false
            }
        ]
    },
    {
        "description": "remote ref, containing refs itself",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "https://json-schema.org/draft/2020-12/schema"
        },
        "tests": [
            {
                "description": "remote ref valid",
                "data": {"minLength": 1},
                "valid": true
            },
            {
                "description": "remote ref invalid",
                "data": {"minLength": -1},
                "valid": false
            }
        ]
    },
    {
        "description": "property named $ref that is not a reference",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "$ref": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "property named $ref valid",
                "data": {"$ref": "a"},
                "valid": true
            },
            {
                "description": "property named $ref invalid",
                "data": {"$ref": 2},
                "valid": false
            }
        ]
    },
    {
        "description": "property named $ref, containing an actual $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "$ref": {"$ref": "#/$defs/is-string"}
            },
            "$defs": {
                "is-string": {
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "property named $ref valid",
                "data": {"$ref": "a"},
                "valid": true
            },
            {
                "description": "property named $ref invalid",
                "data": {"$ref": 2},
                "valid": false
            }
        ]
    },
    {
        "description": "$ref to boolean schema true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "#/$defs/bool",
            "$defs": {
                "bool": true
            }
        },
        "tests": [
            {
                "description": "any value is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "$ref to boolean schema false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "#/$defs/bool",
            "$defs": {
                "bool": false
            }
        },
        "tests": [
            {
                "description": "any value is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "Recursive references between schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/tree",
            "description": "tree of nodes",
            "type": "object",
            "properties": {
                "meta": {"type": "string"},
                "nodes": {
                    "type": "array",
                    "items": {"$ref": "node"}
                }
            },
            "required": ["meta", "nodes"],
            "$defs": {
                "node": {
                    "$id": "http://localhost:1234/draft2020-12/node",
                    "description": "node",
                    "type": "object",
                    "properties": {
                        "value": {"type": "number"},
                        "subtree": {"$ref": "tree"}
                    },
                    "required": ["value"]
                }
            }
        },
        "tests": [
            {
                "description": "valid tree",
                "data": {
                    "meta": "root",
                    "nodes": [
                        {
                            "value": 1,
                            "subtree": {
                                "meta": "child",
                                "nodes": [
                                    {"value": 1.1},
                                    {"value": 1.2}
                                ]
                            }
                        },
                        {
                            "value": 2,
                            "subtree": {
                                "meta": "child",
                                "nodes": [
                                    {"value": 2.1},
                                    {"value": 2.2}
                                ]
                            }
                        }
                    ]
                },
                "valid": true
            },
            {
                "description": "invalid tree",
                "data": {
                    "meta": "root",
                    "nodes": [
                        {
                            "value": 1,
                            "subtree": {
                                "meta": "child",
                                "nodes": [
                                    {"value": "string is invalid"},
                                    {"value": 1.2}
                                ]
                            }
                        },
                        {
                            "value": 2,
                            "subtree": {
                                "meta": "child",
                                "nodes": [
                                    {"value": 2.1},
                                    {"value": 2.2}
                                ]
                            }
                        }
                    ]
                },
                "valid": false
            }
        ]
    },
    {
        "description": "refs with quote",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo\"bar": {"$ref": "#/$defs/foo%22bar"}
            },
            "$defs": {
                "foo\"bar": {"type": "number"}
            }
        },
        "tests": [
            {
                "description": "object with numbers is valid",
                "data": {
                    "foo\"bar": 1
                },
                "valid": true
            },
            {
                "description": "object with strings is invalid",
                "data": {
                    "foo\"bar": "1"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "ref creates new scope when adjacent to keywords",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "A": {
                    "unevaluatedProperties": false
                }
            },
            "properties": {
                "prop1": {
                    "type": "string"
                }
            },
            "$ref": "#/$defs/A"
        },
        "tests": [
            {
                "description": "referenced subschema doesn't see annotations from properties",
                "data": {
                    "prop1": "match"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "naive replacement of $ref with its destination is not correct",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "a_string": { "type": "string" }
            },
            "enum": [
                { "$ref": "#/$defs/a_string" }
            ]
        },
        "tests": [
            {
                "description": "do not evaluate the $ref inside the enum, matching any string",
                "data": "this is a string",
                "valid": false
            },
            {
                "description": "do not evaluate the $ref inside the enum, definition exact match",
                "data": { "type": "string" },
                "valid": false
            },
            {
                "description": "match the enum exactly",
                "data": { "$ref": "#/$defs/a_string" },
                "valid": true
            }
        ]
    },
    {
        "description": "refs with relative uris and defs",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://example.com/schema-relative-uri-defs1.json",
            "properties": {
                "foo": {
                    "$id": "schema-relative-uri-defs2.json",
                    "$defs": {
                        "inner": {
                            "properties": {
                                "bar": { "type": "string" }
                            }
                        }
                    },
                    "$ref": "#/$defs/inner"
                }
            },
            "$ref": "schema-relative-uri-defs2.json"
        },
        "tests": [
            {
                "description": "invalid on inner field",
                "data": {
                    "foo": {
                        "bar": 1
                    },
                    "bar": "a"
                },
                "valid": false
            },
            {
                "description": "invalid on outer field",
                "data": {
                    "foo": {
                        "bar": "a"
                    },
                    "bar": 1
                },
                "valid": false
            },
            {
                "description": "valid on both fields",
                "data": {
                    "foo": {
                        "bar": "a"
                    },
                    "bar": "a"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "relative refs with absolute uris and defs",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://example.com/schema-refs-absolute-uris-defs1.json",
            "properties": {
                "foo": {
                    "$id": "http://example.com/schema-refs-absolute-uris-defs2.json",
                    "$defs": {
                        "inner": {
                            "properties": {
                                "bar": { "type": "string" }
                            }
                        }
                    },
                    "$ref": "#/$defs/inner"
                }
            },
            "$ref": "schema-refs-absolute-uris-defs2.json"
        },
        "tests": [
            {
                "description": "invalid on inner field",
                "data": {
                    "foo": {
                        "bar": 1
                    },
                    "bar": "a"
                },
                "valid": false
            },
            {
                "description": "invalid on outer field",
                "data": {
                    "foo": {
                        "bar": "a"
                    },
                    "bar": 1
                },
                "valid": false
            },
            {
                "description": "valid on both fields",
                "data": {
                    "foo": {
                        "bar": "a"
                    },
                    "bar": "a"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "$id must be resolved against nearest parent, not just immediate parent",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://example.com/a.json",
            "$defs": {
                "x": {
                    "$id": "http://example.com/b/c.json",
                    "not": {
                        "$defs": {
                            "y": {
                                "$id": "d.json",
                                "type": "number"
                            }
                        }
                    }
                }
            },
            "allOf": [
                {
                    "$ref": "http://example.com/b/d.json"
                }
            ]
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "order of evaluation: $id and $ref",
        "schema": {
            "$comment": "$id must be evaluated before $ref to get the proper $ref destination",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://example.com/draft2020-12/ref-and-id1/base.json",
            "$ref": "int.json",
            "$defs": {
                "bigint": {
                    "$comment": "canonical uri: https://example.com/ref-and-id1/int.json",
                    "$id": "int.json",
                    "maximum": 10
                },
                "smallint": {
                    "$comment": "canonical uri: https://example.com/ref-and-id1-int.json",
                    "$id": "/draft2020-12/ref-and-id1-int.json",
                    "maximum": 2
                }
            }
        },
        "tests": [
            {
                "description": "data is valid against first definition",
                "data": 5,
                "valid": true
            },
            {
                "description": "data is invalid against first definition",
                "data": 50,
                "valid": false
            }
        ]
    },
    {
        "description": "order of evaluation: $id and $anchor and $ref",
        "schema": {
            "$comment": "$id must be evaluated before $ref to get the proper $ref destination",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://example.com/draft2020-12/ref-and-id2/base.json",
            "$ref": "#bigint",
            "$defs": {
                "bigint": {
                    "$comment": "canonical uri: /ref-and-id2/base.json#/$defs/bigint; another valid uri for this location: /ref-and-id2/base.json#bigint",
                    "$anchor": "bigint",
                    "maximum": 10
                },
                "smallint": {
                    "$comment": "canonical uri: https://example.com/ref-and-id2#/$defs/smallint; another valid uri for this location: https://example.com/ref-and-id2/#bigint",
                    "$id": "https://example.com/draft2020-12/ref-and-id2/",
                    "$anchor": "bigint",
                    "maximum": 2
                }
            }
        },
        "tests": [
            {
                "description": "data is valid against first definition",
                "data": 5,
                "valid": true
            },
            {
                "description": "data is invalid against first definition",
                "data": 50,
                "valid": false
            }
        ]
    },
    {
        "description": "simple URN base URI with $ref via the URN",
        "schema": {
            "$comment": "URIs do not have to have HTTP(s) schemes",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:uuid:deadbeef-1234-ffff-ffff-4321feebdaed",
            "minimum": 30,
            "properties": {
                "foo": {"$ref": "urn:uuid:deadbeef-1234-ffff-ffff-4321feebdaed"}
            }
        },
        "tests": [
            {
                "description": "valid under the URN IDed schema",
                "data": {"foo": 37},
                "valid": true
            },
            {
                "description": "invalid under the URN IDed schema",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "simple URN base URI with JSON pointer",
        "schema": {
            "$comment": "URIs do not have to have HTTP(s) schemes",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:uuid:deadbeef-1234-00ff-ff00-4321feebdaed",
            "properties": {
                "foo": {"$ref": "#/$defs/bar"}
            },
            "$defs": {
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN base URI with NSS",
        "schema": {
            "$comment": "RFC 8141 §2.2",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:example:1/406/47452/2",
            "properties": {
                "foo": {"$ref": "#/$defs/bar"}
            },
            "$defs": {
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN base URI with r-component",
        "schema": {
            "$comment": "RFC 8141 §2.3.1",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:example:foo-bar-baz-qux?+CCResolve:cc=uk",
            "properties": {
                "foo": {"$ref": "#/$defs/bar"}
            },
            "$defs": {
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN base URI with q-component",
        "schema": {
            "$comment": "RFC 8141 §2.3.2",
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:example:weather?=op=map&lat=39.56&lon=-104.85&datetime=1969-07-21T02:56:15Z",
            "properties": {
                "foo": {"$ref": "#/$defs/bar"}
            },
            "$defs": {
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN base URI with URN and JSON pointer ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:uuid:deadbeef-1234-0000-0000-4321feebdaed",
            "properties": {
                "foo": {"$ref": "urn:uuid:deadbeef-1234-0000-0000-4321feebdaed#/$defs/bar"}
            },
            "$defs": {
                "bar": {"type": "string"}
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN base URI with URN and anchor ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "urn:uuid:deadbeef-1234-ff00-00ff-4321feebdaed",
            "properties": {
                "foo": {"$ref": "urn:uuid:deadbeef-1234-ff00-00ff-4321feebdaed#something"}
            },
            "$defs": {
                "bar": {
                    "$anchor": "something",
                    "type": "string"
                }
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": {"foo": "bar"},
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": {"foo": 12},
                "valid": false
            }
        ]
    },
    {
        "description": "URN ref with nested pointer ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "urn:uuid:deadbeef-4321-ffff-ffff-1234feebdaed",
            "$defs": {
                "foo": {
                    "$id": "urn:uuid:deadbeef-4321-ffff-ffff-1234feebdaed",
                    "$defs": {"bar": {"type": "string"}},
                    "$ref": "#/$defs/bar"
                }
            }
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": "bar",
                "valid": true
            },
            {
                "description": "a non-string is invalid",
                "data": 12,
                "valid": false
            }
        ]
    },
    {
        "description": "ref to if",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://example.com/ref/if",
            "if": {
                "$id": "http://example.com/ref/if",
                "type": "integer"
            }
        },
        "tests": [
            {
                "description": "a non-integer is invalid due to the $ref",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an integer is valid",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "ref to then",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://example.com/ref/then",
            "then": {
                "$id": "http://example.com/ref/then",
                "type": "integer"
            }
        },
        "tests": [
            {
                "description": "a non-integer is invalid due to the $ref",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an integer is valid",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "ref to else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://example.com/ref/else",
            "else": {
                "$id": "http://example.com/ref/else",
                "type": "integer"
            }
        },
        "tests": [
            {
                "description": "a non-integer is invalid due to the $ref",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an integer is valid",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "ref with absolute-path-reference",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://example.com/ref/absref.json",
            "$defs": {
                "a": {
                    "$id": "http://example.com/ref/absref/foobar.json",
                    "type": "number"
                },
                "b": {
                    "$id": "http://example.com/absref/foobar.json",
                    "type": "string"
                }
            },
            "$ref": "/absref/foobar.json"
        },
        "tests": [
            {
                "description": "a string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "an integer is invalid",
                "data": 12,
                "valid": false
            }
        ]
    },
    {
        "description": "$id with file URI still resolves pointers - *nix",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "file:///folder/file.json",
            "$defs": {
                "foo": {
                    "type": "number"
                }
            },
            "$ref": "#/$defs/foo"
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "$id with file URI still resolves pointers - windows",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "file:///c:/folder/file.json",
            "$defs": {
                "foo": {
                    "type": "number"
                }
            },
            "$ref": "#/$defs/foo"
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "empty tokens in $ref json-pointer",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "": {
                    "$defs": {
                        "": { "type": "number" }
                    }
                }
            },
            "allOf": [
                {
                    "$ref": "#/$defs//$defs/"
                }
            ]
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/refRemote.json
================================================
[
    {
        "description": "remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/integer.json"
        },
        "tests": [
            {
                "description": "remote ref valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "remote ref invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "fragment within remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/subSchemas.json#/$defs/integer"
        },
        "tests": [
            {
                "description": "remote fragment valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "remote fragment invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "anchor within remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/locationIndependentIdentifier.json#foo"
        },
        "tests": [
            {
                "description": "remote anchor valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "remote anchor invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "ref within remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/subSchemas.json#/$defs/refToInteger"
        },
        "tests": [
            {
                "description": "ref within ref valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "ref within ref invalid",
                "data": "a",
                "valid": false
            }
        ]
    },
    {
        "description": "base URI change",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/",
            "items": {
                "$id": "baseUriChange/",
                "items": {"$ref": "folderInteger.json"}
            }
        },
        "tests": [
            {
                "description": "base URI change ref valid",
                "data": [[1]],
                "valid": true
            },
            {
                "description": "base URI change ref invalid",
                "data": [["a"]],
                "valid": false
            }
        ]
    },
    {
        "description": "base URI change - change folder",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/scope_change_defs1.json",
            "type" : "object",
            "properties": {"list": {"$ref": "baseUriChangeFolder/"}},
            "$defs": {
                "baz": {
                    "$id": "baseUriChangeFolder/",
                    "type": "array",
                    "items": {"$ref": "folderInteger.json"}
                }
            }
        },
        "tests": [
            {
                "description": "number is valid",
                "data": {"list": [1]},
                "valid": true
            },
            {
                "description": "string is invalid",
                "data": {"list": ["a"]},
                "valid": false
            }
        ]
    },
    {
        "description": "base URI change - change folder in subschema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/scope_change_defs2.json",
            "type" : "object",
            "properties": {"list": {"$ref": "baseUriChangeFolderInSubschema/#/$defs/bar"}},
            "$defs": {
                "baz": {
                    "$id": "baseUriChangeFolderInSubschema/",
                    "$defs": {
                        "bar": {
                            "type": "array",
                            "items": {"$ref": "folderInteger.json"}
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "number is valid",
                "data": {"list": [1]},
                "valid": true
            },
            {
                "description": "string is invalid",
                "data": {"list": ["a"]},
                "valid": false
            }
        ]
    },
    {
        "description": "root ref in remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/object",
            "type": "object",
            "properties": {
                "name": {"$ref": "name-defs.json#/$defs/orNull"}
            }
        },
        "tests": [
            {
                "description": "string is valid",
                "data": {
                    "name": "foo"
                },
                "valid": true
            },
            {
                "description": "null is valid",
                "data": {
                    "name": null
                },
                "valid": true
            },
            {
                "description": "object is invalid",
                "data": {
                    "name": {
                        "name": null
                    }
                },
                "valid": false
            }
        ]
    },
    {
        "description": "remote ref with ref to defs",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/schema-remote-ref-ref-defs1.json",
            "$ref": "ref-and-defs.json"
        },
        "tests": [
            {
                "description": "invalid",
                "data": {
                    "bar": 1
                },
                "valid": false
            },
            {
                "description": "valid",
                "data": {
                    "bar": "a"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "Location-independent identifier in remote ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/locationIndependentIdentifier.json#/$defs/refToInteger"
        },
        "tests": [
            {
                "description": "integer is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    },
    {
        "description": "retrieved nested refs resolve relative to their URI not $id",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "http://localhost:1234/draft2020-12/some-id",
            "properties": {
                "name": {"$ref": "nested/foo-ref-string.json"}
            }
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": {
                    "name": {"foo":  1}
                },
                "valid": false
            },
            {
                "description": "string is valid",
                "data": {
                    "name": {"foo":  "a"}
                },
                "valid": true
            }
        ]
    },
    {
        "description": "remote HTTP ref with different $id",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/different-id-ref-string.json"
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "remote HTTP ref with different URN $id",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/urn-ref-string.json"
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "remote HTTP ref with nested absolute ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/nested-absolute-ref-to-string.json"
        },
        "tests": [
            {
                "description": "number is invalid",
                "data": 1,
                "valid": false
            },
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            }
        ]
    },
    {
        "description": "$ref to $ref finds detached $anchor",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "http://localhost:1234/draft2020-12/detached-ref.json#/$defs/foo"
        },
        "tests": [
            {
                "description": "number is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "non-number is invalid",
                "data": "a",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/required.json
================================================
[
    {
        "description": "required validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {},
                "bar": {}
            },
            "required": ["foo"]
        },
        "tests": [
            {
                "description": "present required property is valid",
                "data": {"foo": 1},
                "valid": true
            },
            {
                "description": "non-present required property is invalid",
                "data": {"bar": 1},
                "valid": false
            },
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "",
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            }
        ]
    },
    {
        "description": "required default validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {}
            }
        },
        "tests": [
            {
                "description": "not required by default",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "required with empty array",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {}
            },
            "required": []
        },
        "tests": [
            {
                "description": "property not required",
                "data": {},
                "valid": true
            }
        ]
    },
    {
        "description": "required with escaped characters",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "required": [
                "foo\nbar",
                "foo\"bar",
                "foo\\bar",
                "foo\rbar",
                "foo\tbar",
                "foo\fbar"
            ]
        },
        "tests": [
            {
                "description": "object with all properties present is valid",
                "data": {
                    "foo\nbar": 1,
                    "foo\"bar": 1,
                    "foo\\bar": 1,
                    "foo\rbar": 1,
                    "foo\tbar": 1,
                    "foo\fbar": 1
                },
                "valid": true
            },
            {
                "description": "object with some properties missing is invalid",
                "data": {
                    "foo\nbar": "1",
                    "foo\"bar": "1"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "required properties whose names are Javascript object property names",
        "comment": "Ensure JS implementations don't universally consider e.g. __proto__ to always be present in an object.",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "required": ["__proto__", "toString", "constructor"]
        },
        "tests": [
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores other non-objects",
                "data": 12,
                "valid": true
            },
            {
                "description": "none of the properties mentioned",
                "data": {},
                "valid": false
            },
            {
                "description": "__proto__ present",
                "data": { "__proto__": "foo" },
                "valid": false
            },
            {
                "description": "toString present",
                "data": { "toString": { "length": 37 } },
                "valid": false
            },
            {
                "description": "constructor present",
                "data": { "constructor": { "length": 37 } },
                "valid": false
            },
            {
                "description": "all present",
                "data": {
                    "__proto__": 12,
                    "toString": { "length": "foo" },
                    "constructor": 37
                },
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/type.json
================================================
[
    {
        "description": "integer type matches integers",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "integer"
        },
        "tests": [
            {
                "description": "an integer is an integer",
                "data": 1,
                "valid": true
            },
            {
                "description": "a float with zero fractional part is an integer",
                "data": 1.0,
                "valid": true
            },
            {
                "description": "a float is not an integer",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "a string is not an integer",
                "data": "foo",
                "valid": false
            },
            {
                "description": "a string is still not an integer, even if it looks like one",
                "data": "1",
                "valid": false
            },
            {
                "description": "an object is not an integer",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is not an integer",
                "data": [],
                "valid": false
            },
            {
                "description": "a boolean is not an integer",
                "data": true,
                "valid": false
            },
            {
                "description": "null is not an integer",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "number type matches numbers",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "number"
        },
        "tests": [
            {
                "description": "an integer is a number",
                "data": 1,
                "valid": true
            },
            {
                "description": "a float with zero fractional part is a number (and an integer)",
                "data": 1.0,
                "valid": true
            },
            {
                "description": "a float is a number",
                "data": 1.1,
                "valid": true
            },
            {
                "description": "a string is not a number",
                "data": "foo",
                "valid": false
            },
            {
                "description": "a string is still not a number, even if it looks like one",
                "data": "1",
                "valid": false
            },
            {
                "description": "an object is not a number",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is not a number",
                "data": [],
                "valid": false
            },
            {
                "description": "a boolean is not a number",
                "data": true,
                "valid": false
            },
            {
                "description": "null is not a number",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "string type matches strings",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "string"
        },
        "tests": [
            {
                "description": "1 is not a string",
                "data": 1,
                "valid": false
            },
            {
                "description": "a float is not a string",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "a string is a string",
                "data": "foo",
                "valid": true
            },
            {
                "description": "a string is still a string, even if it looks like a number",
                "data": "1",
                "valid": true
            },
            {
                "description": "an empty string is still a string",
                "data": "",
                "valid": true
            },
            {
                "description": "an object is not a string",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is not a string",
                "data": [],
                "valid": false
            },
            {
                "description": "a boolean is not a string",
                "data": true,
                "valid": false
            },
            {
                "description": "null is not a string",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "object type matches objects",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object"
        },
        "tests": [
            {
                "description": "an integer is not an object",
                "data": 1,
                "valid": false
            },
            {
                "description": "a float is not an object",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "a string is not an object",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an object is an object",
                "data": {},
                "valid": true
            },
            {
                "description": "an array is not an object",
                "data": [],
                "valid": false
            },
            {
                "description": "a boolean is not an object",
                "data": true,
                "valid": false
            },
            {
                "description": "null is not an object",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "array type matches arrays",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "array"
        },
        "tests": [
            {
                "description": "an integer is not an array",
                "data": 1,
                "valid": false
            },
            {
                "description": "a float is not an array",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "a string is not an array",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an object is not an array",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is an array",
                "data": [],
                "valid": true
            },
            {
                "description": "a boolean is not an array",
                "data": true,
                "valid": false
            },
            {
                "description": "null is not an array",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "boolean type matches booleans",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "boolean"
        },
        "tests": [
            {
                "description": "an integer is not a boolean",
                "data": 1,
                "valid": false
            },
            {
                "description": "zero is not a boolean",
                "data": 0,
                "valid": false
            },
            {
                "description": "a float is not a boolean",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "a string is not a boolean",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an empty string is not a boolean",
                "data": "",
                "valid": false
            },
            {
                "description": "an object is not a boolean",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is not a boolean",
                "data": [],
                "valid": false
            },
            {
                "description": "true is a boolean",
                "data": true,
                "valid": true
            },
            {
                "description": "false is a boolean",
                "data": false,
                "valid": true
            },
            {
                "description": "null is not a boolean",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "null type matches only the null object",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "null"
        },
        "tests": [
            {
                "description": "an integer is not null",
                "data": 1,
                "valid": false
            },
            {
                "description": "a float is not null",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "zero is not null",
                "data": 0,
                "valid": false
            },
            {
                "description": "a string is not null",
                "data": "foo",
                "valid": false
            },
            {
                "description": "an empty string is not null",
                "data": "",
                "valid": false
            },
            {
                "description": "an object is not null",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is not null",
                "data": [],
                "valid": false
            },
            {
                "description": "true is not null",
                "data": true,
                "valid": false
            },
            {
                "description": "false is not null",
                "data": false,
                "valid": false
            },
            {
                "description": "null is null",
                "data": null,
                "valid": true
            }
        ]
    },
    {
        "description": "multiple types can be specified in an array",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": ["integer", "string"]
        },
        "tests": [
            {
                "description": "an integer is valid",
                "data": 1,
                "valid": true
            },
            {
                "description": "a string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "a float is invalid",
                "data": 1.1,
                "valid": false
            },
            {
                "description": "an object is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "an array is invalid",
                "data": [],
                "valid": false
            },
            {
                "description": "a boolean is invalid",
                "data": true,
                "valid": false
            },
            {
                "description": "null is invalid",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "type as array with one item",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": ["string"]
        },
        "tests": [
            {
                "description": "string is valid",
                "data": "foo",
                "valid": true
            },
            {
                "description": "number is invalid",
                "data": 123,
                "valid": false
            }
        ]
    },
    {
        "description": "type: array or object",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": ["array", "object"]
        },
        "tests": [
            {
                "description": "array is valid",
                "data": [1,2,3],
                "valid": true
            },
            {
                "description": "object is valid",
                "data": {"foo": 123},
                "valid": true
            },
            {
                "description": "number is invalid",
                "data": 123,
                "valid": false
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            },
            {
                "description": "null is invalid",
                "data": null,
                "valid": false
            }
        ]
    },
    {
        "description": "type: array, object or null",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": ["array", "object", "null"]
        },
        "tests": [
            {
                "description": "array is valid",
                "data": [1,2,3],
                "valid": true
            },
            {
                "description": "object is valid",
                "data": {"foo": 123},
                "valid": true
            },
            {
                "description": "null is valid",
                "data": null,
                "valid": true
            },
            {
                "description": "number is invalid",
                "data": 123,
                "valid": false
            },
            {
                "description": "string is invalid",
                "data": "foo",
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/unevaluatedItems.json
================================================
[
    {
        "description": "unevaluatedItems true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": true
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": [],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo"],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": [],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems as schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": { "type": "string" }
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": [],
                "valid": true
            },
            {
                "description": "with valid unevaluated items",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "with invalid unevaluated items",
                "data": [42],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with uniform items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": { "type": "string" },
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "unevaluatedItems doesn't apply",
                "data": ["foo", "bar"],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems with tuple",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "type": "string" }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with items and prefixItems",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "type": "string" }
            ],
            "items": true,
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "unevaluatedItems doesn't apply",
                "data": ["foo", 42],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems with items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "items": {"type": "number"},
            "unevaluatedItems": {"type": "string"}
        },
        "tests": [
            {
                "description": "valid under items",
                "comment": "no elements are considered by unevaluatedItems",
                "data": [5, 6, 7, 8],
                "valid": true
            },
            {
                "description": "invalid under items",
                "data": ["foo", "bar", "baz"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with nested tuple",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "type": "string" }
            ],
            "allOf": [
                {
                    "prefixItems": [
                        true,
                        { "type": "number" }
                    ]
                }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo", 42],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", 42, true],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with nested items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": {"type": "boolean"},
            "anyOf": [
                { "items": {"type": "string"} },
                true
            ]
        },
        "tests": [
            {
                "description": "with only (valid) additional items",
                "data": [true, false],
                "valid": true
            },
            {
                "description": "with no additional items",
                "data": ["yes", "no"],
                "valid": true
            },
            {
                "description": "with invalid additional item",
                "data": ["yes", false],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with nested prefixItems and items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "prefixItems": [
                        { "type": "string" }
                    ],
                    "items": true
                }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no additional items",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "with additional items",
                "data": ["foo", 42, true],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems with nested unevaluatedItems",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "prefixItems": [
                        { "type": "string" }
                    ]
                },
                { "unevaluatedItems": true }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no additional items",
                "data": ["foo"],
                "valid": true
            },
            {
                "description": "with additional items",
                "data": ["foo", 42, true],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems with anyOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "const": "foo" }
            ],
            "anyOf": [
                {
                    "prefixItems": [
                        true,
                        { "const": "bar" }
                    ]
                },
                {
                    "prefixItems": [
                        true,
                        true,
                        { "const": "baz" }
                    ]
                }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "when one schema matches and has no unevaluated items",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "when one schema matches and has unevaluated items",
                "data": ["foo", "bar", 42],
                "valid": false
            },
            {
                "description": "when two schemas match and has no unevaluated items",
                "data": ["foo", "bar", "baz"],
                "valid": true
            },
            {
                "description": "when two schemas match and has unevaluated items",
                "data": ["foo", "bar", "baz", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with oneOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "const": "foo" }
            ],
            "oneOf": [
                {
                    "prefixItems": [
                        true,
                        { "const": "bar" }
                    ]
                },
                {
                    "prefixItems": [
                        true,
                        { "const": "baz" }
                    ]
                }
            ],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with not",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "const": "foo" }
            ],
            "not": {
                "not": {
                    "prefixItems": [
                        true,
                        { "const": "bar" }
                    ]
                }
            },
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with if/then/else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [
                { "const": "foo" }
            ],
            "if": {
                "prefixItems": [
                    true,
                    { "const": "bar" }
                ]
            },
            "then": {
                "prefixItems": [
                    true,
                    true,
                    { "const": "then" }
                ]
            },
            "else": {
                "prefixItems": [
                    true,
                    true,
                    true,
                    { "const": "else" }
                ]
            },
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "when if matches and it has no unevaluated items",
                "data": ["foo", "bar", "then"],
                "valid": true
            },
            {
                "description": "when if matches and it has unevaluated items",
                "data": ["foo", "bar", "then", "else"],
                "valid": false
            },
            {
                "description": "when if doesn't match and it has no unevaluated items",
                "data": ["foo", 42, 42, "else"],
                "valid": true
            },
            {
                "description": "when if doesn't match and it has unevaluated items",
                "data": ["foo", 42, 42, "else", 42],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with boolean schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [true],
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": [],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$ref": "#/$defs/bar",
            "prefixItems": [
                { "type": "string" }
            ],
            "unevaluatedItems": false,
            "$defs": {
              "bar": {
                  "prefixItems": [
                      true,
                      { "type": "string" }
                  ]
              }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar", "baz"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems before $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": false,
            "prefixItems": [
                { "type": "string" }
            ],
            "$ref": "#/$defs/bar",
            "$defs": {
              "bar": {
                  "prefixItems": [
                      true,
                      { "type": "string" }
                  ]
              }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar", "baz"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems with $dynamicRef",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://example.com/unevaluated-items-with-dynamic-ref/derived",

            "$ref": "./baseSchema",

            "$defs": {
                "derived": {
                    "$dynamicAnchor": "addons",
                    "prefixItems": [
                        true,
                        { "type": "string" }
                    ]
                },
                "baseSchema": {
                    "$id": "./baseSchema",

                    "$comment": "unevaluatedItems comes first so it's more likely to catch bugs with implementations that are sensitive to keyword ordering",
                    "unevaluatedItems": false,
                    "type": "array",
                    "prefixItems": [
                        { "type": "string" }
                    ],
                    "$dynamicRef": "#addons",

                    "$defs": {
                        "defaultAddons": {
                            "$comment": "Needed to satisfy the bookending requirement",
                            "$dynamicAnchor": "addons"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated items",
                "data": ["foo", "bar"],
                "valid": true
            },
            {
                "description": "with unevaluated items",
                "data": ["foo", "bar", "baz"],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems can't see inside cousins",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "prefixItems": [ true ]
                },
                { "unevaluatedItems": false }
            ]
        },
        "tests": [
            {
                "description": "always fails",
                "data": [ 1 ],
                "valid": false
            }
        ]
    },
    {
        "description": "item is evaluated in an uncle schema to unevaluatedItems",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {
                "foo": {
                    "prefixItems": [
                        { "type": "string" }
                    ],
                    "unevaluatedItems": false
                  }
            },
            "anyOf": [
                {
                    "properties": {
                        "foo": {
                            "prefixItems": [
                                true,
                                { "type": "string" }
                            ]
                        }
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "no extra items",
                "data": {
                    "foo": [
                        "test"
                    ]
                },
                "valid": true
            },
            {
                "description": "uncle keyword evaluation is not significant",
                "data": {
                    "foo": [
                        "test",
                        "test"
                    ]
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems depends on adjacent contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [true],
            "contains": {"type": "string"},
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "second item is evaluated by contains",
                "data": [ 1, "foo" ],
                "valid": true
            },
            {
                "description": "contains fails, second item is not evaluated",
                "data": [ 1, 2 ],
                "valid": false
            },
            {
                "description": "contains passes, second item is not evaluated",
                "data": [ 1, 2, "foo" ],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems depends on multiple nested contains",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                { "contains": { "multipleOf": 2 } },
                { "contains": { "multipleOf": 3 } }
            ],
            "unevaluatedItems": { "multipleOf": 5 }
        },
        "tests": [
            {
                "description": "5 not evaluated, passes unevaluatedItems",
                "data": [ 2, 3, 4, 5, 6 ],
                "valid": true
            },
            {
                "description": "7 not evaluated, fails unevaluatedItems",
                "data": [ 2, 3, 4, 7, 8 ],
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedItems and contains interact to control item dependency relationship",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "contains": {"const": "a"}
            },
            "then": {
                "if": {
                    "contains": {"const": "b"}
                },
                "then": {
                    "if": {
                        "contains": {"const": "c"}
                    }
                }
            },
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "empty array is valid",
                "data": [],
                "valid": true
            },
            {
                "description": "only a's are valid",
                "data": [ "a", "a" ],
                "valid": true
            },
            {
                "description": "a's and b's are valid",
                "data": [ "a", "b", "a", "b", "a" ],
                "valid": true
            },
            {
                "description": "a's, b's and c's are valid",
                "data": [ "c", "a", "c", "c", "b", "a" ],
                "valid": true
            },
            {
                "description": "only b's are invalid",
                "data": [ "b", "b" ],
                "valid": false
            },
            {
                "description": "only c's are invalid",
                "data": [ "c", "c" ],
                "valid": false
            },
            {
                "description": "only b's and c's are invalid",
                "data": [ "c", "b", "c", "b", "c" ],
                "valid": false
            },
            {
                "description": "only a's and c's are invalid",
                "data": [ "c", "a", "c", "a", "c" ],
                "valid": false
            }
        ]
    },
    {
        "description": "non-array instances are valid",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "ignores booleans",
                "data": true,
                "valid": true
            },
            {
                "description": "ignores integers",
                "data": 123,
                "valid": true
            },
            {
                "description": "ignores floats",
                "data": 1.0,
                "valid": true
            },
            {
                "description": "ignores objects",
                "data": {},
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foo",
                "valid": true
            },
            {
                "description": "ignores null",
                "data": null,
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems with null instance elements",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedItems": {
                "type": "null"
            }
        },
        "tests": [
            {
                "description": "allows null elements",
                "data": [ null ],
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedItems can see annotations from if without then and else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "prefixItems": [{"const": "a"}]
            },
            "unevaluatedItems": false
        },
        "tests": [
            {
                "description": "valid in case if is evaluated",
                "data": [ "a" ],
                "valid": true
            },
            {
                "description": "invalid in case if is evaluated",
                "data": [ "b" ],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/unevaluatedProperties.json
================================================
[
    {
        "description": "unevaluatedProperties true",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "unevaluatedProperties": true
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {},
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties schema",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "unevaluatedProperties": {
                "type": "string",
                "minLength": 3
            }
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {},
                "valid": true
            },
            {
                "description": "with valid unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with invalid unevaluated properties",
                "data": {
                    "foo": "fo"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {},
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with adjacent properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with adjacent patternProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "patternProperties": {
                "^foo": { "type": "string" }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with adjacent additionalProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "additionalProperties": true,
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no additional properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties with nested properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
                {
                    "properties": {
                        "bar": { "type": "string" }
                    }
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with nested patternProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
              {
                  "patternProperties": {
                      "^bar": { "type": "string" }
                  }
              }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with nested additionalProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
                {
                    "additionalProperties": true
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no additional properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with additional properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties with nested unevaluatedProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
                {
                    "unevaluatedProperties": true
                }
            ],
            "unevaluatedProperties": {
                "type": "string",
                "maxLength": 2
            }
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties with anyOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "anyOf": [
                {
                    "properties": {
                        "bar": { "const": "bar" }
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "baz": { "const": "baz" }
                    },
                    "required": ["baz"]
                },
                {
                    "properties": {
                        "quux": { "const": "quux" }
                    },
                    "required": ["quux"]
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "when one matches and has no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "when one matches and has unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "not-baz"
                },
                "valid": false
            },
            {
                "description": "when two match and has no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": true
            },
            {
                "description": "when two match and has unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz",
                    "quux": "not-quux"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with oneOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "oneOf": [
                {
                    "properties": {
                        "bar": { "const": "bar" }
                    },
                    "required": ["bar"]
                },
                {
                    "properties": {
                        "baz": { "const": "baz" }
                    },
                    "required": ["baz"]
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "quux": "quux"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with not",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "not": {
                "not": {
                    "properties": {
                        "bar": { "const": "bar" }
                    },
                    "required": ["bar"]
                }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with if/then/else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "if": {
                "properties": {
                    "foo": { "const": "then" }
                },
                "required": ["foo"]
            },
            "then": {
                "properties": {
                    "bar": { "type": "string" }
                },
                "required": ["bar"]
            },
            "else": {
                "properties": {
                    "baz": { "type": "string" }
                },
                "required": ["baz"]
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "when if is true and has no unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "when if is true and has unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            },
            {
                "description": "when if is false and has no unevaluated properties",
                "data": {
                    "baz": "baz"
                },
                "valid": true
            },
            {
                "description": "when if is false and has unevaluated properties",
                "data": {
                    "foo": "else",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with if/then/else, then not defined",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "if": {
                "properties": {
                    "foo": { "const": "then" }
                },
                "required": ["foo"]
            },
            "else": {
                "properties": {
                    "baz": { "type": "string" }
                },
                "required": ["baz"]
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "when if is true and has no unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar"
                },
                "valid": false
            },
            {
                "description": "when if is true and has unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            },
            {
                "description": "when if is false and has no unevaluated properties",
                "data": {
                    "baz": "baz"
                },
                "valid": true
            },
            {
                "description": "when if is false and has unevaluated properties",
                "data": {
                    "foo": "else",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with if/then/else, else not defined",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "if": {
                "properties": {
                    "foo": { "const": "then" }
                },
                "required": ["foo"]
            },
            "then": {
                "properties": {
                    "bar": { "type": "string" }
                },
                "required": ["bar"]
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "when if is true and has no unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "when if is true and has unevaluated properties",
                "data": {
                    "foo": "then",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            },
            {
                "description": "when if is false and has no unevaluated properties",
                "data": {
                    "baz": "baz"
                },
                "valid": false
            },
            {
                "description": "when if is false and has unevaluated properties",
                "data": {
                    "foo": "else",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with dependentSchemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "dependentSchemas": {
                "foo": {
                    "properties": {
                        "bar": { "const": "bar" }
                    },
                    "required": ["bar"]
                }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with boolean schemas",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [true],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "$ref": "#/$defs/bar",
            "properties": {
                "foo": { "type": "string" }
            },
            "unevaluatedProperties": false,
            "$defs": {
                "bar": {
                    "properties": {
                        "bar": { "type": "string" }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties before $ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "unevaluatedProperties": false,
            "properties": {
                "foo": { "type": "string" }
            },
            "$ref": "#/$defs/bar",
            "$defs": {
                "bar": {
                    "properties": {
                        "bar": { "type": "string" }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties with $dynamicRef",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$id": "https://example.com/unevaluated-properties-with-dynamic-ref/derived",

            "$ref": "./baseSchema",

            "$defs": {
                "derived": {
                    "$dynamicAnchor": "addons",
                    "properties": {
                        "bar": { "type": "string" }
                    }
                },
                "baseSchema": {
                    "$id": "./baseSchema",

                    "$comment": "unevaluatedProperties comes first so it's more likely to catch bugs with implementations that are sensitive to keyword ordering",
                    "unevaluatedProperties": false,
                    "type": "object",
                    "properties": {
                        "foo": { "type": "string" }
                    },
                    "$dynamicRef": "#addons",

                    "$defs": {
                        "defaultAddons": {
                            "$comment": "Needed to satisfy the bookending requirement",
                            "$dynamicAnchor": "addons"
                        }
                    }
                }
            }
        },
        "tests": [
            {
                "description": "with no unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            },
            {
                "description": "with unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar",
                    "baz": "baz"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties can't see inside cousins",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "properties": {
                        "foo": true
                    }
                },
                {
                    "unevaluatedProperties": false
                }
            ]
        },
        "tests": [
            {
                "description": "always fails",
                "data": {
                    "foo": 1
                },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties can't see inside cousins (reverse order)",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "allOf": [
                {
                    "unevaluatedProperties": false
                },
                {
                    "properties": {
                        "foo": true
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "always fails",
                "data": {
                    "foo": 1
                },
                "valid": false
            }
        ]
    },
    {
        "description": "nested unevaluatedProperties, outer false, inner true, properties outside",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
                {
                    "unevaluatedProperties": true
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "nested unevaluatedProperties, outer false, inner true, properties inside",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "properties": {
                        "foo": { "type": "string" }
                    },
                    "unevaluatedProperties": true
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": true
            }
        ]
    },
    {
        "description": "nested unevaluatedProperties, outer true, inner false, properties outside",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": { "type": "string" }
            },
            "allOf": [
                {
                    "unevaluatedProperties": false
                }
            ],
            "unevaluatedProperties": true
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": false
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "nested unevaluatedProperties, outer true, inner false, properties inside",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "properties": {
                        "foo": { "type": "string" }
                    },
                    "unevaluatedProperties": false
                }
            ],
            "unevaluatedProperties": true
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "cousin unevaluatedProperties, true and false, true with properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "properties": {
                        "foo": { "type": "string" }
                    },
                    "unevaluatedProperties": true
                },
                {
                    "unevaluatedProperties": false
                }
            ]
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": false
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "cousin unevaluatedProperties, true and false, false with properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "unevaluatedProperties": true
                },
                {
                    "properties": {
                        "foo": { "type": "string" }
                    },
                    "unevaluatedProperties": false
                }
            ]
        },
        "tests": [
            {
                "description": "with no nested unevaluated properties",
                "data": {
                    "foo": "foo"
                },
                "valid": true
            },
            {
                "description": "with nested unevaluated properties",
                "data": {
                    "foo": "foo",
                    "bar": "bar"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "property is evaluated in an uncle schema to unevaluatedProperties",
        "comment": "see https://stackoverflow.com/questions/66936884/deeply-nested-unevaluatedproperties-and-their-expectations",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "foo": {
                    "type": "object",
                    "properties": {
                        "bar": {
                            "type": "string"
                        }
                    },
                    "unevaluatedProperties": false
                  }
            },
            "anyOf": [
                {
                    "properties": {
                        "foo": {
                            "properties": {
                                "faz": {
                                    "type": "string"
                                }
                            }
                        }
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "no extra properties",
                "data": {
                    "foo": {
                        "bar": "test"
                    }
                },
                "valid": true
            },
            {
                "description": "uncle keyword evaluation is not significant",
                "data": {
                    "foo": {
                        "bar": "test",
                        "faz": "test"
                    }
                },
                "valid": false
            }
        ]
    },
    {
        "description": "in-place applicator siblings, allOf has unevaluated",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "properties": {
                        "foo": true
                    },
                    "unevaluatedProperties": false
                }
            ],
            "anyOf": [
                {
                    "properties": {
                        "bar": true
                    }
                }
            ]
        },
        "tests": [
            {
                "description": "base case: both properties present",
                "data": {
                    "foo": 1,
                    "bar": 1
                },
                "valid": false
            },
            {
                "description": "in place applicator siblings, bar is missing",
                "data": {
                    "foo": 1
                },
                "valid": true
            },
            {
                "description": "in place applicator siblings, foo is missing",
                "data": {
                    "bar": 1
                },
                "valid": false
            }
        ]
    },
    {
        "description": "in-place applicator siblings, anyOf has unevaluated",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "allOf": [
                {
                    "properties": {
                        "foo": true
                    }
                }
            ],
            "anyOf": [
                {
                    "properties": {
                        "bar": true
                    },
                    "unevaluatedProperties": false
                }
            ]
        },
        "tests": [
            {
                "description": "base case: both properties present",
                "data": {
                    "foo": 1,
                    "bar": 1
                },
                "valid": false
            },
            {
                "description": "in place applicator siblings, bar is missing",
                "data": {
                    "foo": 1
                },
                "valid": false
            },
            {
                "description": "in place applicator siblings, foo is missing",
                "data": {
                    "bar": 1
                },
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties + single cyclic ref",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "type": "object",
            "properties": {
                "x": { "$ref": "#" }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "Empty is valid",
                "data": {},
                "valid": true
            },
            {
                "description": "Single is valid",
                "data": { "x": {} },
                "valid": true
            },
            {
                "description": "Unevaluated on 1st level is invalid",
                "data": { "x": {}, "y": {} },
                "valid": false
            },
            {
                "description": "Nested is valid",
                "data": { "x": { "x": {} } },
                "valid": true
            },
            {
                "description": "Unevaluated on 2nd level is invalid",
                "data": { "x": { "x": {}, "y": {} } },
                "valid": false
            },
            {
                "description": "Deep nested is valid",
                "data": { "x": { "x": { "x": {} } } },
                "valid": true
            },
            {
                "description": "Unevaluated on 3rd level is invalid",
                "data": { "x": { "x": { "x": {}, "y": {} } } },
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties + ref inside allOf / oneOf",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "one": {
                    "properties": { "a": true }
                },
                "two": {
                    "required": ["x"],
                    "properties": { "x": true }
                }
            },
            "allOf": [
                { "$ref": "#/$defs/one" },
                { "properties": { "b": true } },
                {
                    "oneOf": [
                        { "$ref": "#/$defs/two" },
                        {
                            "required": ["y"],
                            "properties": { "y": true }
                        }
                    ]
                }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "Empty is invalid (no x or y)",
                "data": {},
                "valid": false
            },
            {
                "description": "a and b are invalid (no x or y)",
                "data": { "a": 1, "b": 1 },
                "valid": false
            },
            {
                "description": "x and y are invalid",
                "data": { "x": 1, "y": 1 },
                "valid": false
            },
            {
                "description": "a and x are valid",
                "data": { "a": 1, "x": 1 },
                "valid": true
            },
            {
                "description": "a and y are valid",
                "data": { "a": 1, "y": 1 },
                "valid": true
            },
            {
                "description": "a and b and x are valid",
                "data": { "a": 1, "b": 1, "x": 1 },
                "valid": true
            },
            {
                "description": "a and b and y are valid",
                "data": { "a": 1, "b": 1, "y": 1 },
                "valid": true
            },
            {
                "description": "a and b and x and y are invalid",
                "data": { "a": 1, "b": 1, "x": 1, "y": 1 },
                "valid": false
            }
        ]
    },
    {
        "description": "dynamic evalation inside nested refs",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "$defs": {
                "one": {
                    "oneOf": [
                        { "$ref": "#/$defs/two" },
                        { "required": ["b"], "properties": { "b": true } },
                        { "required": ["xx"], "patternProperties": { "x": true } },
                        { "required": ["all"], "unevaluatedProperties": true }
                    ]
                },
                "two": {
                    "oneOf": [
                        { "required": ["c"], "properties": { "c": true } },
                        { "required": ["d"], "properties": { "d": true } }
                    ]
                }
            },
            "oneOf": [
                { "$ref": "#/$defs/one" },
                { "required": ["a"], "properties": { "a": true } }
            ],
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "Empty is invalid",
                "data": {},
                "valid": false
            },
            {
                "description": "a is valid",
                "data": { "a": 1 },
                "valid": true
            },
            {
                "description": "b is valid",
                "data": { "b": 1 },
                "valid": true
            },
            {
                "description": "c is valid",
                "data": { "c": 1 },
                "valid": true
            },
            {
                "description": "d is valid",
                "data": { "d": 1 },
                "valid": true
            },
            {
                "description": "a + b is invalid",
                "data": { "a": 1, "b": 1 },
                "valid": false
            },
            {
                "description": "a + c is invalid",
                "data": { "a": 1, "c": 1 },
                "valid": false
            },
            {
                "description": "a + d is invalid",
                "data": { "a": 1, "d": 1 },
                "valid": false
            },
            {
                "description": "b + c is invalid",
                "data": { "b": 1, "c": 1 },
                "valid": false
            },
            {
                "description": "b + d is invalid",
                "data": { "b": 1, "d": 1 },
                "valid": false
            },
            {
                "description": "c + d is invalid",
                "data": { "c": 1, "d": 1 },
                "valid": false
            },
            {
                "description": "xx is valid",
                "data": { "xx": 1 },
                "valid": true
            },
            {
                "description": "xx + foox is valid",
                "data": { "xx": 1, "foox": 1 },
                "valid": true
            },
            {
                "description": "xx + foo is invalid",
                "data": { "xx": 1, "foo": 1 },
                "valid": false
            },
            {
                "description": "xx + a is invalid",
                "data": { "xx": 1, "a": 1 },
                "valid": false
            },
            {
                "description": "xx + b is invalid",
                "data": { "xx": 1, "b": 1 },
                "valid": false
            },
            {
                "description": "xx + c is invalid",
                "data": { "xx": 1, "c": 1 },
                "valid": false
            },
            {
                "description": "xx + d is invalid",
                "data": { "xx": 1, "d": 1 },
                "valid": false
            },
            {
                "description": "all is valid",
                "data": { "all": 1 },
                "valid": true
            },
            {
                "description": "all + foo is valid",
                "data": { "all": 1, "foo": 1 },
                "valid": true
            },
            {
                "description": "all + a is invalid",
                "data": { "all": 1, "a": 1 },
                "valid": false
            }
        ]
    },
    {
        "description": "non-object instances are valid",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "ignores booleans",
                "data": true,
                "valid": true
            },
            {
                "description": "ignores integers",
                "data": 123,
                "valid": true
            },
            {
                "description": "ignores floats",
                "data": 1.0,
                "valid": true
            },
            {
                "description": "ignores arrays",
                "data": [],
                "valid": true
            },
            {
                "description": "ignores strings",
                "data": "foo",
                "valid": true
            },
            {
                "description": "ignores null",
                "data": null,
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties with null valued instance properties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "unevaluatedProperties": {
                "type": "null"
            }
        },
        "tests": [
            {
                "description": "allows null valued properties",
                "data": {"foo": null},
                "valid": true
            }
        ]
    },
    {
        "description": "unevaluatedProperties not affected by propertyNames",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "propertyNames": {"maxLength": 1},
            "unevaluatedProperties": {
                "type": "number"
            }
        },
        "tests": [
            {
                "description": "allows only number properties",
                "data": {"a": 1},
                "valid": true
            },
            {
                "description": "string property is invalid",
                "data": {"a": "b"},
                "valid": false
            }
        ]
    },
    {
        "description": "unevaluatedProperties can see annotations from if without then and else",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "if": {
                "patternProperties": {
                    "foo": {
                        "type": "string"
                    }
                }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "valid in case if is evaluated",
                "data": {
                    "foo": "a"
                },
                "valid": true
            },
            {
                "description": "invalid in case if is evaluated",
                "data": {
                    "bar": "a"
                },
                "valid": false
            }
        ]
    },
    {
        "description": "dependentSchemas with unevaluatedProperties",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "properties": {"foo2": {}},
            "dependentSchemas": {
                "foo" : {},
                "foo2": {
                    "properties": {
                        "bar":{}
                    }
                }
            },
            "unevaluatedProperties": false
        },
        "tests": [
            {
                "description": "unevaluatedProperties doesn't consider dependentSchemas",
                "data": {"foo": ""},
                "valid": false
            },
            {
                "description": "unevaluatedProperties doesn't see bar when foo2 is absent",
                "data": {"bar": ""},
                "valid": false
            },
            {
                "description": "unevaluatedProperties sees bar when foo2 is present",
                "data": { "foo2": "", "bar": ""},
                "valid": true
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/draft2020-12/uniqueItems.json
================================================
[
    {
        "description": "uniqueItems validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "uniqueItems": true
        },
        "tests": [
            {
                "description": "unique array of integers is valid",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "non-unique array of integers is invalid",
                "data": [1, 1],
                "valid": false
            },
            {
                "description": "non-unique array of more than two integers is invalid",
                "data": [1, 2, 1],
                "valid": false
            },
            {
                "description": "numbers are unique if mathematically unequal",
                "data": [1.0, 1.00, 1],
                "valid": false
            },
            {
                "description": "false is not equal to zero",
                "data": [0, false],
                "valid": true
            },
            {
                "description": "true is not equal to one",
                "data": [1, true],
                "valid": true
            },
            {
                "description": "unique array of strings is valid",
                "data": ["foo", "bar", "baz"],
                "valid": true
            },
            {
                "description": "non-unique array of strings is invalid",
                "data": ["foo", "bar", "foo"],
                "valid": false
            },
            {
                "description": "unique array of objects is valid",
                "data": [{"foo": "bar"}, {"foo": "baz"}],
                "valid": true
            },
            {
                "description": "non-unique array of objects is invalid",
                "data": [{"foo": "bar"}, {"foo": "bar"}],
                "valid": false
            },
            {
                "description": "property order of array of objects is ignored",
                "data": [{"foo": "bar", "bar": "foo"}, {"bar": "foo", "foo": "bar"}],
                "valid": false
            },
            {
                "description": "unique array of nested objects is valid",
                "data": [
                    {"foo": {"bar" : {"baz" : true}}},
                    {"foo": {"bar" : {"baz" : false}}}
                ],
                "valid": true
            },
            {
                "description": "non-unique array of nested objects is invalid",
                "data": [
                    {"foo": {"bar" : {"baz" : true}}},
                    {"foo": {"bar" : {"baz" : true}}}
                ],
                "valid": false
            },
            {
                "description": "unique array of arrays is valid",
                "data": [["foo"], ["bar"]],
                "valid": true
            },
            {
                "description": "non-unique array of arrays is invalid",
                "data": [["foo"], ["foo"]],
                "valid": false
            },
            {
                "description": "non-unique array of more than two arrays is invalid",
                "data": [["foo"], ["bar"], ["foo"]],
                "valid": false
            },
            {
                "description": "1 and true are unique",
                "data": [1, true],
                "valid": true
            },
            {
                "description": "0 and false are unique",
                "data": [0, false],
                "valid": true
            },
            {
                "description": "[1] and [true] are unique",
                "data": [[1], [true]],
                "valid": true
            },
            {
                "description": "[0] and [false] are unique",
                "data": [[0], [false]],
                "valid": true
            },
            {
                "description": "nested [1] and [true] are unique",
                "data": [[[1], "foo"], [[true], "foo"]],
                "valid": true
            },
            {
                "description": "nested [0] and [false] are unique",
                "data": [[[0], "foo"], [[false], "foo"]],
                "valid": true
            },
            {
                "description": "unique heterogeneous types are valid",
                "data": [{}, [1], true, null, 1, "{}"],
                "valid": true
            },
            {
                "description": "non-unique heterogeneous types are invalid",
                "data": [{}, [1], true, null, {}, 1],
                "valid": false
            },
            {
                "description": "different objects are unique",
                "data": [{"a": 1, "b": 2}, {"a": 2, "b": 1}],
                "valid": true
            },
            {
                "description": "objects are non-unique despite key order",
                "data": [{"a": 1, "b": 2}, {"b": 2, "a": 1}],
                "valid": false
            },
            {
                "description": "{\"a\": false} and {\"a\": 0} are unique",
                "data": [{"a": false}, {"a": 0}],
                "valid": true
            },
            {
                "description": "{\"a\": true} and {\"a\": 1} are unique",
                "data": [{"a": true}, {"a": 1}],
                "valid": true
            }
        ]
    },
    {
        "description": "uniqueItems with an array of items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{"type": "boolean"}, {"type": "boolean"}],
            "uniqueItems": true
        },
        "tests": [
            {
                "description": "[false, true] from items array is valid",
                "data": [false, true],
                "valid": true
            },
            {
                "description": "[true, false] from items array is valid",
                "data": [true, false],
                "valid": true
            },
            {
                "description": "[false, false] from items array is not valid",
                "data": [false, false],
                "valid": false
            },
            {
                "description": "[true, true] from items array is not valid",
                "data": [true, true],
                "valid": false
            },
            {
                "description": "unique array extended from [false, true] is valid",
                "data": [false, true, "foo", "bar"],
                "valid": true
            },
            {
                "description": "unique array extended from [true, false] is valid",
                "data": [true, false, "foo", "bar"],
                "valid": true
            },
            {
                "description": "non-unique array extended from [false, true] is not valid",
                "data": [false, true, "foo", "foo"],
                "valid": false
            },
            {
                "description": "non-unique array extended from [true, false] is not valid",
                "data": [true, false, "foo", "foo"],
                "valid": false
            }
        ]
    },
    {
        "description": "uniqueItems with an array of items and additionalItems=false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{"type": "boolean"}, {"type": "boolean"}],
            "uniqueItems": true,
            "items": false
        },
        "tests": [
            {
                "description": "[false, true] from items array is valid",
                "data": [false, true],
                "valid": true
            },
            {
                "description": "[true, false] from items array is valid",
                "data": [true, false],
                "valid": true
            },
            {
                "description": "[false, false] from items array is not valid",
                "data": [false, false],
                "valid": false
            },
            {
                "description": "[true, true] from items array is not valid",
                "data": [true, true],
                "valid": false
            },
            {
                "description": "extra items are invalid even if unique",
                "data": [false, true, null],
                "valid": false
            }
        ]
    },
    {
        "description": "uniqueItems=false validation",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "uniqueItems": false
        },
        "tests": [
            {
                "description": "unique array of integers is valid",
                "data": [1, 2],
                "valid": true
            },
            {
                "description": "non-unique array of integers is valid",
                "data": [1, 1],
                "valid": true
            },
            {
                "description": "numbers are unique if mathematically unequal",
                "data": [1.0, 1.00, 1],
                "valid": true
            },
            {
                "description": "false is not equal to zero",
                "data": [0, false],
                "valid": true
            },
            {
                "description": "true is not equal to one",
                "data": [1, true],
                "valid": true
            },
            {
                "description": "unique array of objects is valid",
                "data": [{"foo": "bar"}, {"foo": "baz"}],
                "valid": true
            },
            {
                "description": "non-unique array of objects is valid",
                "data": [{"foo": "bar"}, {"foo": "bar"}],
                "valid": true
            },
            {
                "description": "unique array of nested objects is valid",
                "data": [
                    {"foo": {"bar" : {"baz" : true}}},
                    {"foo": {"bar" : {"baz" : false}}}
                ],
                "valid": true
            },
            {
                "description": "non-unique array of nested objects is valid",
                "data": [
                    {"foo": {"bar" : {"baz" : true}}},
                    {"foo": {"bar" : {"baz" : true}}}
                ],
                "valid": true
            },
            {
                "description": "unique array of arrays is valid",
                "data": [["foo"], ["bar"]],
                "valid": true
            },
            {
                "description": "non-unique array of arrays is valid",
                "data": [["foo"], ["foo"]],
                "valid": true
            },
            {
                "description": "1 and true are unique",
                "data": [1, true],
                "valid": true
            },
            {
                "description": "0 and false are unique",
                "data": [0, false],
                "valid": true
            },
            {
                "description": "unique heterogeneous types are valid",
                "data": [{}, [1], true, null, 1],
                "valid": true
            },
            {
                "description": "non-unique heterogeneous types are valid",
                "data": [{}, [1], true, null, {}, 1],
                "valid": true
            }
        ]
    },
    {
        "description": "uniqueItems=false with an array of items",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{"type": "boolean"}, {"type": "boolean"}],
            "uniqueItems": false
        },
        "tests": [
            {
                "description": "[false, true] from items array is valid",
                "data": [false, true],
                "valid": true
            },
            {
                "description": "[true, false] from items array is valid",
                "data": [true, false],
                "valid": true
            },
            {
                "description": "[false, false] from items array is valid",
                "data": [false, false],
                "valid": true
            },
            {
                "description": "[true, true] from items array is valid",
                "data": [true, true],
                "valid": true
            },
            {
                "description": "unique array extended from [false, true] is valid",
                "data": [false, true, "foo", "bar"],
                "valid": true
            },
            {
                "description": "unique array extended from [true, false] is valid",
                "data": [true, false, "foo", "bar"],
                "valid": true
            },
            {
                "description": "non-unique array extended from [false, true] is valid",
                "data": [false, true, "foo", "foo"],
                "valid": true
            },
            {
                "description": "non-unique array extended from [true, false] is valid",
                "data": [true, false, "foo", "foo"],
                "valid": true
            }
        ]
    },
    {
        "description": "uniqueItems=false with an array of items and additionalItems=false",
        "schema": {
            "$schema": "https://json-schema.org/draft/2020-12/schema",
            "prefixItems": [{"type": "boolean"}, {"type": "boolean"}],
            "uniqueItems": false,
            "items": false
        },
        "tests": [
            {
                "description": "[false, true] from items array is valid",
                "data": [false, true],
                "valid": true
            },
            {
                "description": "[true, false] from items array is valid",
                "data": [true, false],
                "valid": true
            },
            {
                "description": "[false, false] from items array is valid",
                "data": [false, false],
                "valid": true
            },
            {
                "description": "[true, true] from items array is valid",
                "data": [true, true],
                "valid": true
            },
            {
                "description": "extra items are invalid even if unique",
                "data": [false, true, null],
                "valid": false
            }
        ]
    }
]


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/README.md
================================================
# JSON Schema test suite: remote references

These files were copied from
https://github.com/json-schema-org/JSON-Schema-Test-Suite/tree/83e866b46c9f9e7082fd51e83a61c5f2145a1ab7/remotes.


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/different-id-ref-string.json
================================================
{
    "$id": "http://localhost:1234/real-id-ref-string.json",
    "$defs": {"bar": {"type": "string"}},
    "$ref": "#/$defs/bar"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/baseUriChange/folderInteger.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "integer"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/baseUriChangeFolder/folderInteger.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "integer"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/baseUriChangeFolderInSubschema/folderInteger.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "integer"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/detached-dynamicref.json
================================================
{
  "$id": "http://localhost:1234/draft2020-12/detached-dynamicref.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$defs": {
    "foo": {
      "$dynamicRef": "#detached"
    },
    "detached": {
      "$dynamicAnchor": "detached",
      "type": "integer"
    }
  }
}

================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/detached-ref.json
================================================
{
  "$id": "http://localhost:1234/draft2020-12/detached-ref.json",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$defs": {
    "foo": {
      "$ref": "#detached"
    },
    "detached": {
      "$anchor": "detached",
      "type": "integer"
    }
  }
}

================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/extendible-dynamic-ref.json
================================================
{
    "description": "extendible array",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "http://localhost:1234/draft2020-12/extendible-dynamic-ref.json",
    "type": "object",
    "properties": {
        "elements": {
            "type": "array",
            "items": {
                "$dynamicRef": "#elements"
            }
        }
    },
    "required": ["elements"],
    "additionalProperties": false,
    "$defs": {
        "elements": {
            "$dynamicAnchor": "elements"
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/format-assertion-false.json
================================================
{
    "$id": "http://localhost:1234/draft2020-12/format-assertion-false.json",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$vocabulary": {
        "https://json-schema.org/draft/2020-12/vocab/core": true,
        "https://json-schema.org/draft/2020-12/vocab/format-assertion": false
    },
    "$dynamicAnchor": "meta",
    "allOf": [
        { "$ref": "https://json-schema.org/draft/2020-12/meta/core" },
        { "$ref": "https://json-schema.org/draft/2020-12/meta/format-assertion" }
    ]
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/format-assertion-true.json
================================================
{
    "$id": "http://localhost:1234/draft2020-12/format-assertion-true.json",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$vocabulary": {
        "https://json-schema.org/draft/2020-12/vocab/core": true,
        "https://json-schema.org/draft/2020-12/vocab/format-assertion": true
    },
    "$dynamicAnchor": "meta",
    "allOf": [
        { "$ref": "https://json-schema.org/draft/2020-12/meta/core" },
        { "$ref": "https://json-schema.org/draft/2020-12/meta/format-assertion" }
    ]
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/integer.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "integer"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/locationIndependentIdentifier.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$defs": {
        "refToInteger": {
            "$ref": "#foo"
        },
        "A": {
            "$anchor": "foo",
            "type": "integer"
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/metaschema-no-validation.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "http://localhost:1234/draft2020-12/metaschema-no-validation.json",
    "$vocabulary": {
        "https://json-schema.org/draft/2020-12/vocab/applicator": true,
        "https://json-schema.org/draft/2020-12/vocab/core": true
    },
    "$dynamicAnchor": "meta",
    "allOf": [
        { "$ref": "https://json-schema.org/draft/2020-12/meta/applicator" },
        { "$ref": "https://json-schema.org/draft/2020-12/meta/core" }
    ]
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/metaschema-optional-vocabulary.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "http://localhost:1234/draft2020-12/metaschema-optional-vocabulary.json",
    "$vocabulary": {
        "https://json-schema.org/draft/2020-12/vocab/validation": true,
        "https://json-schema.org/draft/2020-12/vocab/core": true,
        "http://localhost:1234/draft/2020-12/vocab/custom": false
    },
    "$dynamicAnchor": "meta",
    "allOf": [
        { "$ref": "https://json-schema.org/draft/2020-12/meta/validation" },
        { "$ref": "https://json-schema.org/draft/2020-12/meta/core" }
    ]
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/name-defs.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$defs": {
        "orNull": {
            "anyOf": [
                {
                    "type": "null"
                },
                {
                    "$ref": "#"
                }
            ]
        }
    },
    "type": "string"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/nested/foo-ref-string.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
        "foo": {"$ref": "string.json"}
    }
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/nested/string.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "string"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/prefixItems.json
================================================
{
    "$id": "http://localhost:1234/draft2020-12/prefixItems.json",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "prefixItems": [
        {"type": "string"}
    ]
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/ref-and-defs.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "http://localhost:1234/draft2020-12/ref-and-defs.json",
    "$defs": {
        "inner": {
            "properties": {
                "bar": { "type": "string" }
            }
        }
    },
    "$ref": "#/$defs/inner"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/subSchemas.json
================================================
{
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$defs": {
        "integer": {
            "type": "integer"
        },
        "refToInteger": {
            "$ref": "#/$defs/integer"
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/draft2020-12/tree.json
================================================
{
    "description": "tree schema, extensible",
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "$id": "http://localhost:1234/draft2020-12/tree.json",
    "$dynamicAnchor": "node",

    "type": "object",
    "properties": {
        "data": true,
        "children": {
            "type": "array",
            "items": {
                "$dynamicRef": "#node"
            }
        }
    }
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/nested-absolute-ref-to-string.json
================================================
{
    "$defs": {
        "bar": {
            "$id": "http://localhost:1234/the-nested-id.json",
            "type": "string"
        }
    },
    "$ref": "http://localhost:1234/the-nested-id.json"
}


================================================
FILE: internal/mcp/jsonschema/testdata/remotes/urn-ref-string.json
================================================
{
    "$id": "urn:uuid:feebdaed-ffff-0000-ffff-0000deadbeef",
    "$defs": {"bar": {"type": "string"}},
    "$ref": "#/$defs/bar"
}


================================================
FILE: internal/mcp/jsonschema/util.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"bytes"
	"cmp"
	"encoding/binary"
	"encoding/json"
	"fmt"
	"hash/maphash"
	"math"
	"math/big"
	"reflect"
	"slices"
)

// Equal reports whether two Go values representing JSON values are equal according
// to the JSON Schema spec.
// The values must not contain cycles.
// See https://json-schema.org/draft/2020-12/json-schema-core#section-4.2.2.
// It behaves like reflect.DeepEqual, except that numbers are compared according
// to mathematical equality.
func Equal(x, y any) bool {
	return equalValue(reflect.ValueOf(x), reflect.ValueOf(y))
}

func equalValue(x, y reflect.Value) bool {
	// Copied from src/reflect/deepequal.go, omitting the visited check (because JSON
	// values are trees).
	if !x.IsValid() || !y.IsValid() {
		return x.IsValid() == y.IsValid()
	}

	// Treat numbers specially.
	rx, ok1 := jsonNumber(x)
	ry, ok2 := jsonNumber(y)
	if ok1 && ok2 {
		return rx.Cmp(ry) == 0
	}
	if x.Kind() != y.Kind() {
		return false
	}
	switch x.Kind() {
	case reflect.Array:
		if x.Len() != y.Len() {
			return false
		}
		for i := range x.Len() {
			if !equalValue(x.Index(i), y.Index(i)) {
				return false
			}
		}
		return true
	case reflect.Slice:
		if x.IsNil() != y.IsNil() {
			return false
		}
		if x.Len() != y.Len() {
			return false
		}
		if x.UnsafePointer() == y.UnsafePointer() {
			return true
		}
		// Special case for []byte, which is common.
		if x.Type().Elem().Kind() == reflect.Uint8 && x.Type() == y.Type() {
			return bytes.Equal(x.Bytes(), y.Bytes())
		}
		for i := range x.Len() {
			if !equalValue(x.Index(i), y.Index(i)) {
				return false
			}
		}
		return true
	case reflect.Interface:
		if x.IsNil() || y.IsNil() {
			return x.IsNil() == y.IsNil()
		}
		return equalValue(x.Elem(), y.Elem())
	case reflect.Pointer:
		if x.UnsafePointer() == y.UnsafePointer() {
			return true
		}
		return equalValue(x.Elem(), y.Elem())
	case reflect.Struct:
		t := x.Type()
		if t != y.Type() {
			return false
		}
		for i := range t.NumField() {
			sf := t.Field(i)
			if !sf.IsExported() {
				continue
			}
			if !equalValue(x.FieldByIndex(sf.Index), y.FieldByIndex(sf.Index)) {
				return false
			}
		}
		return true
	case reflect.Map:
		if x.IsNil() != y.IsNil() {
			return false
		}
		if x.Len() != y.Len() {
			return false
		}
		if x.UnsafePointer() == y.UnsafePointer() {
			return true
		}
		iter := x.MapRange()
		for iter.Next() {
			vx := iter.Value()
			vy := y.MapIndex(iter.Key())
			if !vy.IsValid() || !equalValue(vx, vy) {
				return false
			}
		}
		return true
	case reflect.Func:
		if x.Type() != y.Type() {
			return false
		}
		if x.IsNil() && y.IsNil() {
			return true
		}
		panic("cannot compare functions")
	case reflect.String:
		return x.String() == y.String()
	case reflect.Bool:
		return x.Bool() == y.Bool()
	// Ints, uints and floats handled in jsonNumber, at top of function.
	default:
		panic(fmt.Sprintf("unsupported kind: %s", x.Kind()))
	}
}

// hashValue adds v to the data hashed by h. v must not have cycles.
// hashValue panics if the value contains functions or channels, or maps whose
// key type is not string.
// It ignores unexported fields of structs.
// Calls to hashValue with the equal values (in the sense
// of [Equal]) result in the same sequence of values written to the hash.
func hashValue(h *maphash.Hash, v reflect.Value) {
	// TODO: replace writes of basic types with WriteComparable in 1.24.

	writeUint := func(u uint64) {
		var buf [8]byte
		binary.BigEndian.PutUint64(buf[:], u)
		h.Write(buf[:])
	}

	var write func(reflect.Value)
	write = func(v reflect.Value) {
		if r, ok := jsonNumber(v); ok {
			// We want 1.0 and 1 to hash the same.
			// big.Rats are always normalized, so they will be.
			// We could do this more efficiently by handling the int and float cases
			// separately, but that's premature.
			writeUint(uint64(r.Sign() + 1))
			h.Write(r.Num().Bytes())
			h.Write(r.Denom().Bytes())
			return
		}
		switch v.Kind() {
		case reflect.Invalid:
			h.WriteByte(0)
		case reflect.String:
			h.WriteString(v.String())
		case reflect.Bool:
			if v.Bool() {
				h.WriteByte(1)
			} else {
				h.WriteByte(0)
			}
		case reflect.Complex64, reflect.Complex128:
			c := v.Complex()
			writeUint(math.Float64bits(real(c)))
			writeUint(math.Float64bits(imag(c)))
		case reflect.Array, reflect.Slice:
			// Although we could treat []byte more efficiently,
			// JSON values are unlikely to contain them.
			writeUint(uint64(v.Len()))
			for i := range v.Len() {
				write(v.Index(i))
			}
		case reflect.Interface, reflect.Pointer:
			write(v.Elem())
		case reflect.Struct:
			t := v.Type()
			for i := range t.NumField() {
				if sf := t.Field(i); sf.IsExported() {
					write(v.FieldByIndex(sf.Index))
				}
			}
		case reflect.Map:
			if v.Type().Key().Kind() != reflect.String {
				panic("map with non-string key")
			}
			// Sort the keys so the hash is deterministic.
			keys := v.MapKeys()
			// Write the length. That distinguishes between, say, two consecutive
			// maps with disjoint keys from one map that has the items of both.
			writeUint(uint64(len(keys)))
			slices.SortFunc(keys, func(x, y reflect.Value) int { return cmp.Compare(x.String(), y.String()) })
			for _, k := range keys {
				write(k)
				write(v.MapIndex(k))
			}
		// Ints, uints and floats handled in jsonNumber, at top of function.
		default:
			panic(fmt.Sprintf("unsupported kind: %s", v.Kind()))
		}
	}

	write(v)
}

// jsonNumber converts a numeric value or a json.Number to a [big.Rat].
// If v is not a number, it returns nil, false.
func jsonNumber(v reflect.Value) (*big.Rat, bool) {
	r := new(big.Rat)
	switch {
	case !v.IsValid():
		return nil, false
	case v.CanInt():
		r.SetInt64(v.Int())
	case v.CanUint():
		r.SetUint64(v.Uint())
	case v.CanFloat():
		r.SetFloat64(v.Float())
	default:
		jn, ok := v.Interface().(json.Number)
		if !ok {
			return nil, false
		}
		if _, ok := r.SetString(jn.String()); !ok {
			// This can fail in rare cases; for example, "1e9999999".
			// That is a valid JSON number, since the spec puts no limit on the size
			// of the exponent.
			return nil, false
		}
	}
	return r, true
}

// jsonType returns a string describing the type of the JSON value,
// as described in the JSON Schema specification:
// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.1.1.
// It returns "", false if the value is not valid JSON.
func jsonType(v reflect.Value) (string, bool) {
	if !v.IsValid() {
		// Not v.IsNil(): a nil []any is still a JSON array.
		return "null", true
	}
	if v.CanInt() || v.CanUint() {
		return "integer", true
	}
	if v.CanFloat() {
		if _, f := math.Modf(v.Float()); f == 0 {
			return "integer", true
		}
		return "number", true
	}
	switch v.Kind() {
	case reflect.Bool:
		return "boolean", true
	case reflect.String:
		return "string", true
	case reflect.Slice, reflect.Array:
		return "array", true
	case reflect.Map, reflect.Struct:
		return "object", true
	default:
		return "", false
	}
}

func assert(cond bool, msg string) {
	if !cond {
		panic("assertion failed: " + msg)
	}
}


================================================
FILE: internal/mcp/jsonschema/util_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"encoding/json"
	"hash/maphash"
	"reflect"
	"testing"
)

func TestEqual(t *testing.T) {
	for _, tt := range []struct {
		x1, x2 any
		want   bool
	}{
		{0, 1, false},
		{1, 1.0, true},
		{nil, 0, false},
		{"0", 0, false},
		{2.5, 2.5, true},
		{[]int{1, 2}, []float64{1.0, 2.0}, true},
		{[]int(nil), []int{}, false},
		{[]map[string]any(nil), []map[string]any{}, false},
		{
			map[string]any{"a": 1, "b": 2.0},
			map[string]any{"a": 1.0, "b": 2},
			true,
		},
	} {
		check := func(x1, x2 any, want bool) {
			t.Helper()
			if got := Equal(x1, x2); got != want {
				t.Errorf("jsonEqual(%#v, %#v) = %t, want %t", x1, x2, got, want)
			}
		}
		check(tt.x1, tt.x1, true)
		check(tt.x2, tt.x2, true)
		check(tt.x1, tt.x2, tt.want)
		check(tt.x2, tt.x1, tt.want)
	}
}

func TestJSONType(t *testing.T) {
	for _, tt := range []struct {
		val  string
		want string
	}{
		{`null`, "null"},
		{`0`, "integer"},
		{`0.0`, "integer"},
		{`1e2`, "integer"},
		{`0.1`, "number"},
		{`""`, "string"},
		{`true`, "boolean"},
		{`[]`, "array"},
		{`{}`, "object"},
	} {
		var val any
		if err := json.Unmarshal([]byte(tt.val), &val); err != nil {
			t.Fatal(err)
		}
		got, ok := jsonType(reflect.ValueOf(val))
		if !ok {
			t.Fatalf("jsonType failed on %q", tt.val)
		}
		if got != tt.want {
			t.Errorf("%s: got %q, want %q", tt.val, got, tt.want)
		}

	}
}

func TestHash(t *testing.T) {
	x := map[string]any{
		"s": []any{1, "foo", nil, true},
		"f": 2.5,
		"m": map[string]any{
			"n":      json.Number("123.456"),
			"schema": &Schema{Type: "integer", UniqueItems: true},
		},
		"c": 1.2 + 3.4i,
		"n": nil,
	}

	seed := maphash.MakeSeed()

	hash := func(x any) uint64 {
		var h maphash.Hash
		h.SetSeed(seed)
		hashValue(&h, reflect.ValueOf(x))
		return h.Sum64()
	}

	want := hash(x)
	// Run several times to verify consistency.
	for range 10 {
		if got := hash(x); got != want {
			t.Errorf("hash values differ: %d vs. %d", got, want)
		}
	}

	// Check mathematically equal values.
	nums := []any{
		5,
		uint(5),
		5.0,
		json.Number("5"),
		json.Number("5.00"),
	}
	for i, n := range nums {
		if i == 0 {
			want = hash(n)
		} else if got := hash(n); got != want {
			t.Errorf("hashes differ between %v (%[1]T) and %v (%[2]T)", nums[0], n)
		}
	}

	// Check that a bare JSON `null` is OK.
	var null any
	if err := json.Unmarshal([]byte(`null`), &null); err != nil {
		t.Fatal(err)
	}
	_ = hash(null)
}


================================================
FILE: internal/mcp/jsonschema/validate.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"encoding/json"
	"fmt"
	"hash/maphash"
	"iter"
	"math"
	"math/big"
	"reflect"
	"slices"
	"strings"
	"sync"
	"unicode/utf8"

	"golang.org/x/tools/internal/mcp/internal/util"
)

// The value of the "$schema" keyword for the version that we can validate.
const draft202012 = "https://json-schema.org/draft/2020-12/schema"

// Validate validates the instance, which must be a JSON value, against the schema.
// It returns nil if validation is successful or an error if it is not.
func (rs *Resolved) Validate(instance any) error {
	if s := rs.root.Schema; s != "" && s != draft202012 {
		return fmt.Errorf("cannot validate version %s, only %s", s, draft202012)
	}
	st := &state{rs: rs}
	return st.validate(reflect.ValueOf(instance), st.rs.root, nil)
}

// validateDefaults walks the schema tree. If it finds a default, it validates it
// against the schema containing it.
//
// TODO(jba): account for dynamic refs. This algorithm simple-mindedly
// treats each schema with a default as its own root.
func (rs *Resolved) validateDefaults() error {
	if s := rs.root.Schema; s != "" && s != draft202012 {
		return fmt.Errorf("cannot validate version %s, only %s", s, draft202012)
	}
	st := &state{rs: rs}
	for s := range rs.root.all() {
		// We checked for nil schemas in [Schema.Resolve].
		assert(s != nil, "nil schema")
		if s.DynamicRef != "" {
			return fmt.Errorf("jsonschema: %s: validateDefaults does not support dynamic refs", s)
		}
		if s.Default != nil {
			var d any
			if err := json.Unmarshal(s.Default, &d); err != nil {
				return fmt.Errorf("unmarshaling default value of schema %s: %w", s, err)
			}
			if err := st.validate(reflect.ValueOf(d), s, nil); err != nil {
				return err
			}
		}
	}
	return nil
}

// state is the state of single call to ResolvedSchema.Validate.
type state struct {
	rs *Resolved
	// stack holds the schemas from recursive calls to validate.
	// These are the "dynamic scopes" used to resolve dynamic references.
	// https://json-schema.org/draft/2020-12/json-schema-core#scopes
	stack []*Schema
}

// validate validates the reflected value of the instance.
func (st *state) validate(instance reflect.Value, schema *Schema, callerAnns *annotations) (err error) {
	defer util.Wrapf(&err, "validating %s", schema)

	// Maintain a stack for dynamic schema resolution.
	st.stack = append(st.stack, schema) // push
	defer func() {
		st.stack = st.stack[:len(st.stack)-1] // pop
	}()

	// We checked for nil schemas in [Schema.Resolve].
	assert(schema != nil, "nil schema")

	// Step through interfaces and pointers.
	for instance.Kind() == reflect.Pointer || instance.Kind() == reflect.Interface {
		instance = instance.Elem()
	}

	// type: https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.1.1
	if schema.Type != "" || schema.Types != nil {
		gotType, ok := jsonType(instance)
		if !ok {
			return fmt.Errorf("type: %v of type %[1]T is not a valid JSON value", instance)
		}
		if schema.Type != "" {
			// "number" subsumes integers
			if !(gotType == schema.Type ||
				gotType == "integer" && schema.Type == "number") {
				return fmt.Errorf("type: %v has type %q, want %q", instance, gotType, schema.Type)
			}
		} else {
			if !(slices.Contains(schema.Types, gotType) || (gotType == "integer" && slices.Contains(schema.Types, "number"))) {
				return fmt.Errorf("type: %v has type %q, want one of %q",
					instance, gotType, strings.Join(schema.Types, ", "))
			}
		}
	}
	// enum: https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.1.2
	if schema.Enum != nil {
		ok := false
		for _, e := range schema.Enum {
			if equalValue(reflect.ValueOf(e), instance) {
				ok = true
				break
			}
		}
		if !ok {
			return fmt.Errorf("enum: %v does not equal any of: %v", instance, schema.Enum)
		}
	}

	// const: https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.1.3
	if schema.Const != nil {
		if !equalValue(reflect.ValueOf(*schema.Const), instance) {
			return fmt.Errorf("const: %v does not equal %v", instance, *schema.Const)
		}
	}

	// numbers: https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.2
	if schema.MultipleOf != nil || schema.Minimum != nil || schema.Maximum != nil || schema.ExclusiveMinimum != nil || schema.ExclusiveMaximum != nil {
		n, ok := jsonNumber(instance)
		if ok { // these keywords don't apply to non-numbers
			if schema.MultipleOf != nil {
				// TODO: validate MultipleOf as non-zero.
				// The test suite assumes floats.
				nf, _ := n.Float64() // don't care if it's exact or not
				if _, f := math.Modf(nf / *schema.MultipleOf); f != 0 {
					return fmt.Errorf("multipleOf: %s is not a multiple of %f", n, *schema.MultipleOf)
				}
			}

			m := new(big.Rat) // reuse for all of the following
			cmp := func(f float64) int { return n.Cmp(m.SetFloat64(f)) }

			if schema.Minimum != nil && cmp(*schema.Minimum) < 0 {
				return fmt.Errorf("minimum: %s is less than %f", n, *schema.Minimum)
			}
			if schema.Maximum != nil && cmp(*schema.Maximum) > 0 {
				return fmt.Errorf("maximum: %s is greater than %f", n, *schema.Maximum)
			}
			if schema.ExclusiveMinimum != nil && cmp(*schema.ExclusiveMinimum) <= 0 {
				return fmt.Errorf("exclusiveMinimum: %s is less than or equal to %f", n, *schema.ExclusiveMinimum)
			}
			if schema.ExclusiveMaximum != nil && cmp(*schema.ExclusiveMaximum) >= 0 {
				return fmt.Errorf("exclusiveMaximum: %s is greater than or equal to %f", n, *schema.ExclusiveMaximum)
			}
		}
	}

	// strings: https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.3
	if instance.Kind() == reflect.String && (schema.MinLength != nil || schema.MaxLength != nil || schema.Pattern != "") {
		str := instance.String()
		n := utf8.RuneCountInString(str)
		if schema.MinLength != nil {
			if m := *schema.MinLength; n < m {
				return fmt.Errorf("minLength: %q contains %d Unicode code points, fewer than %d", str, n, m)
			}
		}
		if schema.MaxLength != nil {
			if m := *schema.MaxLength; n > m {
				return fmt.Errorf("maxLength: %q contains %d Unicode code points, more than %d", str, n, m)
			}
		}

		if schema.Pattern != "" && !schema.pattern.MatchString(str) {
			return fmt.Errorf("pattern: %q does not match regular expression %q", str, schema.Pattern)
		}
	}

	var anns annotations // all the annotations for this call and child calls

	// $ref: https://json-schema.org/draft/2020-12/json-schema-core#section-8.2.3.1
	if schema.Ref != "" {
		if err := st.validate(instance, schema.resolvedRef, &anns); err != nil {
			return err
		}
	}

	// $dynamicRef: https://json-schema.org/draft/2020-12/json-schema-core#section-8.2.3.2
	if schema.DynamicRef != "" {
		// The ref behaves lexically or dynamically, but not both.
		assert((schema.resolvedDynamicRef == nil) != (schema.dynamicRefAnchor == ""),
			"DynamicRef not resolved properly")
		if schema.resolvedDynamicRef != nil {
			// Same as $ref.
			if err := st.validate(instance, schema.resolvedDynamicRef, &anns); err != nil {
				return err
			}
		} else {
			// Dynamic behavior.
			// Look for the base of the outermost schema on the stack with this dynamic
			// anchor. (Yes, outermost: the one farthest from here. This the opposite
			// of how ordinary dynamic variables behave.)
			// Why the base of the schema being validated and not the schema itself?
			// Because the base is the scope for anchors. In fact it's possible to
			// refer to a schema that is not on the stack, but a child of some base
			// on the stack.
			// For an example, search for "detached" in testdata/draft2020-12/dynamicRef.json.
			var dynamicSchema *Schema
			for _, s := range st.stack {
				info, ok := s.base.anchors[schema.dynamicRefAnchor]
				if ok && info.dynamic {
					dynamicSchema = info.schema
					break
				}
			}
			if dynamicSchema == nil {
				return fmt.Errorf("missing dynamic anchor %q", schema.dynamicRefAnchor)
			}
			if err := st.validate(instance, dynamicSchema, &anns); err != nil {
				return err
			}
		}
	}

	// logic
	// https://json-schema.org/draft/2020-12/json-schema-core#section-10.2
	// These must happen before arrays and objects because if they evaluate an item or property,
	// then the unevaluatedItems/Properties schemas don't apply to it.
	// See https://json-schema.org/draft/2020-12/json-schema-core#section-11.2, paragraph 4.
	//
	// If any of these fail, then validation fails, even if there is an unevaluatedXXX
	// keyword in the schema. The spec is unclear about this, but that is the intention.

	valid := func(s *Schema, anns *annotations) bool { return st.validate(instance, s, anns) == nil }

	if schema.AllOf != nil {
		for _, ss := range schema.AllOf {
			if err := st.validate(instance, ss, &anns); err != nil {
				return err
			}
		}
	}
	if schema.AnyOf != nil {
		// We must visit them all, to collect annotations.
		ok := false
		for _, ss := range schema.AnyOf {
			if valid(ss, &anns) {
				ok = true
			}
		}
		if !ok {
			return fmt.Errorf("anyOf: did not validate against any of %v", schema.AnyOf)
		}
	}
	if schema.OneOf != nil {
		// Exactly one.
		var okSchema *Schema
		for _, ss := range schema.OneOf {
			if valid(ss, &anns) {
				if okSchema != nil {
					return fmt.Errorf("oneOf: validated against both %v and %v", okSchema, ss)
				}
				okSchema = ss
			}
		}
		if okSchema == nil {
			return fmt.Errorf("oneOf: did not validate against any of %v", schema.OneOf)
		}
	}
	if schema.Not != nil {
		// Ignore annotations from "not".
		if valid(schema.Not, nil) {
			return fmt.Errorf("not: validated against %v", schema.Not)
		}
	}
	if schema.If != nil {
		var ss *Schema
		if valid(schema.If, &anns) {
			ss = schema.Then
		} else {
			ss = schema.Else
		}
		if ss != nil {
			if err := st.validate(instance, ss, &anns); err != nil {
				return err
			}
		}
	}

	// arrays
	// TODO(jba): consider arrays of structs.
	if instance.Kind() == reflect.Array || instance.Kind() == reflect.Slice {
		// https://json-schema.org/draft/2020-12/json-schema-core#section-10.3.1
		// This validate call doesn't collect annotations for the items of the instance; they are separate
		// instances in their own right.
		// TODO(jba): if the test suite doesn't cover this case, add a test. For example, nested arrays.
		for i, ischema := range schema.PrefixItems {
			if i >= instance.Len() {
				break // shorter is OK
			}
			if err := st.validate(instance.Index(i), ischema, nil); err != nil {
				return err
			}
		}
		anns.noteEndIndex(min(len(schema.PrefixItems), instance.Len()))

		if schema.Items != nil {
			for i := len(schema.PrefixItems); i < instance.Len(); i++ {
				if err := st.validate(instance.Index(i), schema.Items, nil); err != nil {
					return err
				}
			}
			// Note that all the items in this array have been validated.
			anns.allItems = true
		}

		nContains := 0
		if schema.Contains != nil {
			for i := range instance.Len() {
				if err := st.validate(instance.Index(i), schema.Contains, nil); err == nil {
					nContains++
					anns.noteIndex(i)
				}
			}
			if nContains == 0 && (schema.MinContains == nil || *schema.MinContains > 0) {
				return fmt.Errorf("contains: %s does not have an item matching %s", instance, schema.Contains)
			}
		}

		// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.4
		// TODO(jba): check that these next four keywords' values are integers.
		if schema.MinContains != nil && schema.Contains != nil {
			if m := *schema.MinContains; nContains < m {
				return fmt.Errorf("minContains: contains validated %d items, less than %d", nContains, m)
			}
		}
		if schema.MaxContains != nil && schema.Contains != nil {
			if m := *schema.MaxContains; nContains > m {
				return fmt.Errorf("maxContains: contains validated %d items, greater than %d", nContains, m)
			}
		}
		if schema.MinItems != nil {
			if m := *schema.MinItems; instance.Len() < m {
				return fmt.Errorf("minItems: array length %d is less than %d", instance.Len(), m)
			}
		}
		if schema.MaxItems != nil {
			if m := *schema.MaxItems; instance.Len() > m {
				return fmt.Errorf("maxItems: array length %d is greater than %d", instance.Len(), m)
			}
		}
		if schema.UniqueItems {
			if instance.Len() > 1 {
				// Hash each item and compare the hashes.
				// If two hashes differ, the items differ.
				// If two hashes are the same, compare the collisions for equality.
				// (The same logic as hash table lookup.)
				// TODO(jba): Use container/hash.Map when it becomes available (https://go.dev/issue/69559),
				hashes := map[uint64][]int{} // from hash to indices
				seed := maphash.MakeSeed()
				for i := range instance.Len() {
					item := instance.Index(i)
					var h maphash.Hash
					h.SetSeed(seed)
					hashValue(&h, item)
					hv := h.Sum64()
					if sames := hashes[hv]; len(sames) > 0 {
						for _, j := range sames {
							if equalValue(item, instance.Index(j)) {
								return fmt.Errorf("uniqueItems: array items %d and %d are equal", i, j)
							}
						}
					}
					hashes[hv] = append(hashes[hv], i)
				}
			}
		}

		// https://json-schema.org/draft/2020-12/json-schema-core#section-11.2
		if schema.UnevaluatedItems != nil && !anns.allItems {
			// Apply this subschema to all items in the array that haven't been successfully validated.
			// That includes validations by subschemas on the same instance, like allOf.
			for i := anns.endIndex; i < instance.Len(); i++ {
				if !anns.evaluatedIndexes[i] {
					if err := st.validate(instance.Index(i), schema.UnevaluatedItems, nil); err != nil {
						return err
					}
				}
			}
			anns.allItems = true
		}
	}

	// objects
	// https://json-schema.org/draft/2020-12/json-schema-core#section-10.3.2
	if instance.Kind() == reflect.Map || instance.Kind() == reflect.Struct {
		if instance.Kind() == reflect.Map {
			if kt := instance.Type().Key(); kt.Kind() != reflect.String {
				return fmt.Errorf("map key type %s is not a string", kt)
			}
		}
		// Track the evaluated properties for just this schema, to support additionalProperties.
		// If we used anns here, then we'd be including properties evaluated in subschemas
		// from allOf, etc., which additionalProperties shouldn't observe.
		evalProps := map[string]bool{}
		for prop, subschema := range schema.Properties {
			val := property(instance, prop)
			if !val.IsValid() {
				// It's OK if the instance doesn't have the property.
				continue
			}
			// If the instance is a struct and an optional property has the zero
			// value, then we could interpret it as present or missing. Be generous:
			// assume it's missing, and thus always validates successfully.
			if instance.Kind() == reflect.Struct && val.IsZero() && !schema.isRequired[prop] {
				continue
			}
			if err := st.validate(val, subschema, nil); err != nil {
				return err
			}
			evalProps[prop] = true
		}
		if len(schema.PatternProperties) > 0 {
			for prop, val := range properties(instance) {
				// Check every matching pattern.
				for re, schema := range schema.patternProperties {
					if re.MatchString(prop) {
						if err := st.validate(val, schema, nil); err != nil {
							return err
						}
						evalProps[prop] = true
					}
				}
			}
		}
		if schema.AdditionalProperties != nil {
			// Apply to all properties not handled above.
			for prop, val := range properties(instance) {
				if !evalProps[prop] {
					if err := st.validate(val, schema.AdditionalProperties, nil); err != nil {
						return err
					}
					evalProps[prop] = true
				}
			}
		}
		anns.noteProperties(evalProps)
		if schema.PropertyNames != nil {
			// Note: properties unnecessarily fetches each value. We could define a propertyNames function
			// if performance ever matters.
			for prop := range properties(instance) {
				if err := st.validate(reflect.ValueOf(prop), schema.PropertyNames, nil); err != nil {
					return err
				}
			}
		}

		// https://json-schema.org/draft/2020-12/draft-bhutton-json-schema-validation-01#section-6.5
		var min, max int
		if schema.MinProperties != nil || schema.MaxProperties != nil {
			min, max = numPropertiesBounds(instance, schema.isRequired)
		}
		if schema.MinProperties != nil {
			if n, m := max, *schema.MinProperties; n < m {
				return fmt.Errorf("minProperties: object has %d properties, less than %d", n, m)
			}
		}
		if schema.MaxProperties != nil {
			if n, m := min, *schema.MaxProperties; n > m {
				return fmt.Errorf("maxProperties: object has %d properties, greater than %d", n, m)
			}
		}

		hasProperty := func(prop string) bool {
			return property(instance, prop).IsValid()
		}

		missingProperties := func(props []string) []string {
			var missing []string
			for _, p := range props {
				if !hasProperty(p) {
					missing = append(missing, p)
				}
			}
			return missing
		}

		if schema.Required != nil {
			if m := missingProperties(schema.Required); len(m) > 0 {
				return fmt.Errorf("required: missing properties: %q", m)
			}
		}
		if schema.DependentRequired != nil {
			// "Validation succeeds if, for each name that appears in both the instance
			// and as a name within this keyword's value, every item in the corresponding
			// array is also the name of a property in the instance." §6.5.4
			for dprop, reqs := range schema.DependentRequired {
				if hasProperty(dprop) {
					if m := missingProperties(reqs); len(m) > 0 {
						return fmt.Errorf("dependentRequired[%q]: missing properties %q", dprop, m)
					}
				}
			}
		}

		// https://json-schema.org/draft/2020-12/json-schema-core#section-10.2.2.4
		if schema.DependentSchemas != nil {
			// This does not collect annotations, although it seems like it should.
			for dprop, ss := range schema.DependentSchemas {
				if hasProperty(dprop) {
					// TODO: include dependentSchemas[dprop] in the errors.
					err := st.validate(instance, ss, &anns)
					if err != nil {
						return err
					}
				}
			}
		}
		if schema.UnevaluatedProperties != nil && !anns.allProperties {
			// This looks a lot like AdditionalProperties, but depends on in-place keywords like allOf
			// in addition to sibling keywords.
			for prop, val := range properties(instance) {
				if !anns.evaluatedProperties[prop] {
					if err := st.validate(val, schema.UnevaluatedProperties, nil); err != nil {
						return err
					}
				}
			}
			// The spec says the annotation should be the set of evaluated properties, but we can optimize
			// by setting a single boolean, since after this succeeds all properties will be validated.
			// See https://json-schema.slack.com/archives/CT7FF623C/p1745592564381459.
			anns.allProperties = true
		}
	}

	if callerAnns != nil {
		// Our caller wants to know what we've validated.
		callerAnns.merge(&anns)
	}
	return nil
}

// resolveDynamicRef returns the schema referred to by the argument schema's
// $dynamicRef value.
// It returns an error if the dynamic reference has no referent.
// If there is no $dynamicRef, resolveDynamicRef returns nil, nil.
// See https://json-schema.org/draft/2020-12/json-schema-core#section-8.2.3.2.
func (st *state) resolveDynamicRef(schema *Schema) (*Schema, error) {
	if schema.DynamicRef == "" {
		return nil, nil
	}
	// The ref behaves lexically or dynamically, but not both.
	assert((schema.resolvedDynamicRef == nil) != (schema.dynamicRefAnchor == ""),
		"DynamicRef not statically resolved properly")
	if r := schema.resolvedDynamicRef; r != nil {
		// Same as $ref.
		return r, nil
	}
	// Dynamic behavior.
	// Look for the base of the outermost schema on the stack with this dynamic
	// anchor. (Yes, outermost: the one farthest from here. This the opposite
	// of how ordinary dynamic variables behave.)
	// Why the base of the schema being validated and not the schema itself?
	// Because the base is the scope for anchors. In fact it's possible to
	// refer to a schema that is not on the stack, but a child of some base
	// on the stack.
	// For an example, search for "detached" in testdata/draft2020-12/dynamicRef.json.
	for _, s := range st.stack {
		info, ok := s.base.anchors[schema.dynamicRefAnchor]
		if ok && info.dynamic {
			return info.schema, nil
		}
	}
	return nil, fmt.Errorf("missing dynamic anchor %q", schema.dynamicRefAnchor)
}

// ApplyDefaults modifies an instance by applying the schema's defaults to it. If
// a schema or sub-schema has a default, then a corresponding zero instance value
// is set to the default.
//
// The JSON Schema specification does not describe how defaults should be interpreted.
// This method honors defaults only on properties, and only those that are not required.
// If the instance is a map and the property is missing, the property is added to
// the map with the default.
// If the instance is a struct, the field corresponding to the property exists, and
// its value is zero, the field is set to the default.
// ApplyDefaults can panic if a default cannot be assigned to a field.
//
// The argument must be a pointer to the instance.
// (In case we decide that top-level defaults are meaningful.)
//
// It is recommended to first call Resolve with a ValidateDefaults option of true,
// then call this method, and lastly call Validate.
//
// TODO(jba): consider what defaults on top-level or array instances might mean.
// TODO(jba): follow $ref and $dynamicRef
// TODO(jba): apply defaults on sub-schemas to corresponding sub-instances.
func (rs *Resolved) ApplyDefaults(instancep any) error {
	st := &state{rs: rs}
	return st.applyDefaults(reflect.ValueOf(instancep), rs.root)
}

// Leave this as a potentially recursive helper function, because we'll surely want
// to apply defaults on sub-schemas someday.
func (st *state) applyDefaults(instancep reflect.Value, schema *Schema) (err error) {
	defer util.Wrapf(&err, "applyDefaults: schema %s, instance %v", schema, instancep)

	instance := instancep.Elem()
	if instance.Kind() == reflect.Map || instance.Kind() == reflect.Struct {
		if instance.Kind() == reflect.Map {
			if kt := instance.Type().Key(); kt.Kind() != reflect.String {
				return fmt.Errorf("map key type %s is not a string", kt)
			}
		}
		for prop, subschema := range schema.Properties {
			// Ignore defaults on required properties. (A required property shouldn't have a default.)
			if schema.isRequired[prop] {
				continue
			}
			val := property(instance, prop)
			switch instance.Kind() {
			case reflect.Map:
				// If there is a default for this property, and the map key is missing,
				// set the map value to the default.
				if subschema.Default != nil && !val.IsValid() {
					// Create an lvalue, since map values aren't addressable.
					lvalue := reflect.New(instance.Type().Elem())
					if err := json.Unmarshal(subschema.Default, lvalue.Interface()); err != nil {
						return err
					}
					instance.SetMapIndex(reflect.ValueOf(prop), lvalue.Elem())
				}
			case reflect.Struct:
				// If there is a default for this property, and the field exists but is zero,
				// set the field to the default.
				if subschema.Default != nil && val.IsValid() && val.IsZero() {
					if err := json.Unmarshal(subschema.Default, val.Addr().Interface()); err != nil {
						return err
					}
				}
			default:
				panic(fmt.Sprintf("applyDefaults: property %s: bad value %s of kind %s",
					prop, instance, instance.Kind()))
			}
		}
	}
	return nil
}

// property returns the value of the property of v with the given name, or the invalid
// reflect.Value if there is none.
// If v is a map, the property is the value of the map whose key is name.
// If v is a struct, the property is the value of the field with the given name according
// to the encoding/json package (see [jsonName]).
// If v is anything else, property panics.
func property(v reflect.Value, name string) reflect.Value {
	switch v.Kind() {
	case reflect.Map:
		return v.MapIndex(reflect.ValueOf(name))
	case reflect.Struct:
		props := structPropertiesOf(v.Type())
		// Ignore nonexistent properties.
		if sf, ok := props[name]; ok {
			return v.FieldByIndex(sf.Index)
		}
		return reflect.Value{}
	default:
		panic(fmt.Sprintf("property(%q): bad value %s of kind %s", name, v, v.Kind()))
	}
}

// properties returns an iterator over the names and values of all properties
// in v, which must be a map or a struct.
// If a struct, zero-valued properties that are marked omitempty or omitzero
// are excluded.
func properties(v reflect.Value) iter.Seq2[string, reflect.Value] {
	return func(yield func(string, reflect.Value) bool) {
		switch v.Kind() {
		case reflect.Map:
			for k, e := range v.Seq2() {
				if !yield(k.String(), e) {
					return
				}
			}
		case reflect.Struct:
			for name, sf := range structPropertiesOf(v.Type()) {
				val := v.FieldByIndex(sf.Index)
				if val.IsZero() {
					info := util.FieldJSONInfo(sf)
					if info.Settings["omitempty"] || info.Settings["omitzero"] {
						continue
					}
				}
				if !yield(name, val) {
					return
				}
			}
		default:
			panic(fmt.Sprintf("bad value %s of kind %s", v, v.Kind()))
		}
	}
}

// numPropertiesBounds returns bounds on the number of v's properties.
// v must be a map or a struct.
// If v is a map, both bounds are the map's size.
// If v is a struct, the max is the number of struct properties.
// But since we don't know whether a zero value indicates a missing optional property
// or not, be generous and use the number of non-zero properties as the min.
func numPropertiesBounds(v reflect.Value, isRequired map[string]bool) (int, int) {
	switch v.Kind() {
	case reflect.Map:
		return v.Len(), v.Len()
	case reflect.Struct:
		sp := structPropertiesOf(v.Type())
		min := 0
		for prop, sf := range sp {
			if !v.FieldByIndex(sf.Index).IsZero() || isRequired[prop] {
				min++
			}
		}
		return min, len(sp)
	default:
		panic(fmt.Sprintf("properties: bad value: %s of kind %s", v, v.Kind()))
	}
}

// A propertyMap is a map from property name to struct field index.
type propertyMap = map[string]reflect.StructField

var structProperties sync.Map // from reflect.Type to propertyMap

// structPropertiesOf returns the JSON Schema properties for the struct type t.
// The caller must not mutate the result.
func structPropertiesOf(t reflect.Type) propertyMap {
	// Mutex not necessary: at worst we'll recompute the same value.
	if props, ok := structProperties.Load(t); ok {
		return props.(propertyMap)
	}
	props := map[string]reflect.StructField{}
	for _, sf := range reflect.VisibleFields(t) {
		info := util.FieldJSONInfo(sf)
		if !info.Omit {
			props[info.Name] = sf
		}
	}
	structProperties.Store(t, props)
	return props
}


================================================
FILE: internal/mcp/jsonschema/validate_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package jsonschema

import (
	"encoding/json"
	"fmt"
	"net/url"
	"os"
	"path/filepath"
	"reflect"
	"strings"
	"testing"
)

// The test for validation uses the official test suite, expressed as a set of JSON files.
// Each file is an array of group objects.

// A testGroup consists of a schema and some tests on it.
type testGroup struct {
	Description string
	Schema      *Schema
	Tests       []test
}

// A test consists of a JSON instance to be validated and the expected result.
type test struct {
	Description string
	Data        any
	Valid       bool
}

func TestValidate(t *testing.T) {
	files, err := filepath.Glob(filepath.FromSlash("testdata/draft2020-12/*.json"))
	if err != nil {
		t.Fatal(err)
	}
	if len(files) == 0 {
		t.Fatal("no files")
	}
	for _, file := range files {
		base := filepath.Base(file)
		t.Run(base, func(t *testing.T) {
			data, err := os.ReadFile(file)
			if err != nil {
				t.Fatal(err)
			}
			var groups []testGroup
			if err := json.Unmarshal(data, &groups); err != nil {
				t.Fatal(err)
			}
			for _, g := range groups {
				t.Run(g.Description, func(t *testing.T) {
					rs, err := g.Schema.Resolve(&ResolveOptions{Loader: loadRemote})
					if err != nil {
						t.Fatal(err)
					}
					for _, test := range g.Tests {
						t.Run(test.Description, func(t *testing.T) {
							err = rs.Validate(test.Data)
							if err != nil && test.Valid {
								t.Errorf("wanted success, but failed with: %v", err)
							}
							if err == nil && !test.Valid {
								t.Error("succeeded but wanted failure")
							}
							if t.Failed() {
								t.Errorf("schema: %s", g.Schema.json())
								t.Fatalf("instance: %v (%[1]T)", test.Data)
							}
						})
					}
				})
			}
		})
	}
}

func TestValidateErrors(t *testing.T) {
	schema := &Schema{
		PrefixItems: []*Schema{{Contains: &Schema{Type: "integer"}}},
	}
	rs, err := schema.Resolve(nil)
	if err != nil {
		t.Fatal(err)
	}
	err = rs.Validate([]any{[]any{"1"}})
	want := "prefixItems/0"
	if err == nil || !strings.Contains(err.Error(), want) {
		t.Errorf("error:\n%s\ndoes not contain %q", err, want)
	}
}

func TestValidateDefaults(t *testing.T) {
	s := &Schema{
		Properties: map[string]*Schema{
			"a": {Type: "integer", Default: mustMarshal(1)},
			"b": {Type: "string", Default: mustMarshal("s")},
		},
		Default: mustMarshal(map[string]any{"a": 1, "b": "two"}),
	}
	if _, err := s.Resolve(&ResolveOptions{ValidateDefaults: true}); err != nil {
		t.Fatal(err)
	}

	s = &Schema{
		Properties: map[string]*Schema{
			"a": {Type: "integer", Default: mustMarshal(3)},
			"b": {Type: "string", Default: mustMarshal("s")},
		},
		Default: mustMarshal(map[string]any{"a": 1, "b": 2}),
	}
	_, err := s.Resolve(&ResolveOptions{ValidateDefaults: true})
	want := `has type "integer", want "string"`
	if err == nil || !strings.Contains(err.Error(), want) {
		t.Errorf("Resolve returned error %q, want %q", err, want)
	}
}

func TestApplyDefaults(t *testing.T) {
	schema := &Schema{
		Properties: map[string]*Schema{
			"A": {Default: mustMarshal(1)},
			"B": {Default: mustMarshal(2)},
			"C": {Default: mustMarshal(3)},
		},
		Required: []string{"C"},
	}
	rs, err := schema.Resolve(&ResolveOptions{ValidateDefaults: true})
	if err != nil {
		t.Fatal(err)
	}

	type S struct{ A, B, C int }
	for _, tt := range []struct {
		instancep any // pointer to instance value
		want      any // desired value (not a pointer)
	}{
		{
			&map[string]any{"B": 0},
			map[string]any{
				"A": float64(1), // filled from default
				"B": 0,          // untouched: it was already there
				// "C" not added: it is required (Validate will catch that)
			},
		},
		{
			&S{B: 1},
			S{
				A: 1, // filled from default
				B: 1, // untouched: non-zero
				C: 0, // untouched: required
			},
		},
	} {
		if err := rs.ApplyDefaults(tt.instancep); err != nil {
			t.Fatal(err)
		}
		got := reflect.ValueOf(tt.instancep).Elem().Interface() // dereference the pointer
		if !reflect.DeepEqual(got, tt.want) {
			t.Errorf("\ngot  %#v\nwant %#v", got, tt.want)
		}
	}
}

func TestStructInstance(t *testing.T) {
	instance := struct {
		I int
		B bool `json:"b"`
		P *int // either missing or nil
		u int  // unexported: not a property
	}{1, true, nil, 0}

	for _, tt := range []struct {
		s    Schema
		want bool
	}{
		{
			Schema{MinProperties: Ptr(4)},
			false,
		},
		{
			Schema{MinProperties: Ptr(3)},
			true, // P interpreted as present
		},
		{
			Schema{MaxProperties: Ptr(1)},
			false,
		},
		{
			Schema{MaxProperties: Ptr(2)},
			true, // P interpreted as absent
		},
		{
			Schema{Required: []string{"i"}}, // the name is "I"
			false,
		},
		{
			Schema{Required: []string{"B"}}, // the name is "b"
			false,
		},
		{
			Schema{PropertyNames: &Schema{MinLength: Ptr(2)}},
			false,
		},
		{
			Schema{Properties: map[string]*Schema{"b": {Type: "boolean"}}},
			true,
		},
		{
			Schema{Properties: map[string]*Schema{"b": {Type: "number"}}},
			false,
		},
		{
			Schema{Required: []string{"I"}},
			true,
		},
		{
			Schema{Required: []string{"I", "P"}},
			true, // P interpreted as present
		},
		{
			Schema{Required: []string{"I", "P"}, Properties: map[string]*Schema{"P": {Type: "number"}}},
			false, // P interpreted as present, but not a number
		},
		{
			Schema{Required: []string{"I"}, Properties: map[string]*Schema{"P": {Type: "number"}}},
			true, // P not required, so interpreted as absent
		},
		{
			Schema{Required: []string{"I"}, AdditionalProperties: falseSchema()},
			false,
		},
		{
			Schema{DependentRequired: map[string][]string{"b": {"u"}}},
			false,
		},
		{
			Schema{DependentSchemas: map[string]*Schema{"b": falseSchema()}},
			false,
		},
		{
			Schema{UnevaluatedProperties: falseSchema()},
			false,
		},
	} {
		res, err := tt.s.Resolve(nil)
		if err != nil {
			t.Fatal(err)
		}
		err = res.Validate(instance)
		if err == nil && !tt.want {
			t.Errorf("succeeded unexpectedly\nschema = %s", tt.s.json())
		} else if err != nil && tt.want {
			t.Errorf("Validate: %v\nschema = %s", err, tt.s.json())
		}
	}
}

func mustMarshal(x any) json.RawMessage {
	data, err := json.Marshal(x)
	if err != nil {
		panic(err)
	}
	return json.RawMessage(data)
}

// loadRemote loads a remote reference used in the test suite.
func loadRemote(uri *url.URL) (*Schema, error) {
	// Anything with localhost:1234 refers to the remotes directory in the test suite repo.
	if uri.Host == "localhost:1234" {
		return loadSchemaFromFile(filepath.FromSlash(filepath.Join("testdata/remotes", uri.Path)))
	}
	// One test needs the meta-schema files.
	const metaPrefix = "https://json-schema.org/draft/2020-12/"
	if after, ok := strings.CutPrefix(uri.String(), metaPrefix); ok {
		return loadSchemaFromFile(filepath.FromSlash("meta-schemas/draft2020-12/" + after + ".json"))
	}
	return nil, fmt.Errorf("don't know how to load %s", uri)
}

func loadSchemaFromFile(filename string) (*Schema, error) {
	data, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	var s Schema
	if err := json.Unmarshal(data, &s); err != nil {
		return nil, fmt.Errorf("unmarshaling JSON at %s: %w", filename, err)
	}
	return &s, nil
}


================================================
FILE: internal/mcp/logging.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"cmp"
	"context"
	"encoding/json"
	"log/slog"
	"sync"
	"time"
)

// Logging levels.
const (
	LevelDebug     = slog.LevelDebug
	LevelInfo      = slog.LevelInfo
	LevelNotice    = (slog.LevelInfo + slog.LevelWarn) / 2
	LevelWarning   = slog.LevelWarn
	LevelError     = slog.LevelError
	LevelCritical  = slog.LevelError + 4
	LevelAlert     = slog.LevelError + 8
	LevelEmergency = slog.LevelError + 12
)

var slogToMCP = map[slog.Level]LoggingLevel{
	LevelDebug:     "debug",
	LevelInfo:      "info",
	LevelNotice:    "notice",
	LevelWarning:   "warning",
	LevelError:     "error",
	LevelCritical:  "critical",
	LevelAlert:     "alert",
	LevelEmergency: "emergency",
}

var mcpToSlog = make(map[LoggingLevel]slog.Level)

func init() {
	for sl, ml := range slogToMCP {
		mcpToSlog[ml] = sl
	}
}

func slogLevelToMCP(sl slog.Level) LoggingLevel {
	if ml, ok := slogToMCP[sl]; ok {
		return ml
	}
	return "debug" // for lack of a better idea
}

func mcpLevelToSlog(ll LoggingLevel) slog.Level {
	if sl, ok := mcpToSlog[ll]; ok {
		return sl
	}
	// TODO: is there a better default?
	return LevelDebug
}

// compareLevels behaves like [cmp.Compare] for [LoggingLevel]s.
func compareLevels(l1, l2 LoggingLevel) int {
	return cmp.Compare(mcpLevelToSlog(l1), mcpLevelToSlog(l2))
}

// LoggingHandlerOptions are options for a LoggingHandler.
type LoggingHandlerOptions struct {
	// The value for the "logger" field of logging notifications.
	LoggerName string
	// Limits the rate at which log messages are sent.
	// If zero, there is no rate limiting.
	MinInterval time.Duration
}

// A LoggingHandler is a [slog.Handler] for MCP.
type LoggingHandler struct {
	opts LoggingHandlerOptions
	ss   *ServerSession
	// Ensures that the buffer reset is atomic with the write (see Handle).
	// A pointer so that clones share the mutex. See
	// https://github.com/golang/example/blob/master/slog-handler-guide/README.md#getting-the-mutex-right.
	mu              *sync.Mutex
	lastMessageSent time.Time // for rate-limiting
	buf             *bytes.Buffer
	handler         slog.Handler
}

// NewLoggingHandler creates a [LoggingHandler] that logs to the given [ServerSession] using a
// [slog.JSONHandler].
func NewLoggingHandler(ss *ServerSession, opts *LoggingHandlerOptions) *LoggingHandler {
	var buf bytes.Buffer
	jsonHandler := slog.NewJSONHandler(&buf, &slog.HandlerOptions{
		ReplaceAttr: func(_ []string, a slog.Attr) slog.Attr {
			// Remove level: it appears in LoggingMessageParams.
			if a.Key == slog.LevelKey {
				return slog.Attr{}
			}
			return a
		},
	})
	lh := &LoggingHandler{
		ss:      ss,
		mu:      new(sync.Mutex),
		buf:     &buf,
		handler: jsonHandler,
	}
	if opts != nil {
		lh.opts = *opts
	}
	return lh
}

// Enabled implements [slog.Handler.Enabled] by comparing level to the [ServerSession]'s level.
func (h *LoggingHandler) Enabled(ctx context.Context, level slog.Level) bool {
	// This is also checked in ServerSession.LoggingMessage, so checking it here
	// is just an optimization that skips building the JSON.
	h.ss.mu.Lock()
	mcpLevel := h.ss.logLevel
	h.ss.mu.Unlock()
	return level >= mcpLevelToSlog(mcpLevel)
}

// WithAttrs implements [slog.Handler.WithAttrs].
func (h *LoggingHandler) WithAttrs(as []slog.Attr) slog.Handler {
	h2 := *h
	h2.handler = h.handler.WithAttrs(as)
	return &h2
}

// WithGroup implements [slog.Handler.WithGroup].
func (h *LoggingHandler) WithGroup(name string) slog.Handler {
	h2 := *h
	h2.handler = h.handler.WithGroup(name)
	return &h2
}

// Handle implements [slog.Handler.Handle] by writing the Record to a JSONHandler,
// then calling [ServerSession.LoggingMesssage] with the result.
func (h *LoggingHandler) Handle(ctx context.Context, r slog.Record) error {
	err := h.handle(ctx, r)
	// TODO(jba): find a way to surface the error.
	// The return value will probably be ignored.
	return err
}

func (h *LoggingHandler) handle(ctx context.Context, r slog.Record) error {
	// Observe the rate limit.
	// TODO(jba): use golang.org/x/time/rate. (We can't here because it would require adding
	// golang.org/x/time to the go.mod file.)
	h.mu.Lock()
	skip := time.Since(h.lastMessageSent) < h.opts.MinInterval
	h.mu.Unlock()
	if skip {
		return nil
	}

	var err error
	// Make the buffer reset atomic with the record write.
	// We are careful here in the unlikely event that the handler panics.
	// We don't want to hold the lock for the entire function, because Notify is
	// an I/O operation.
	// This can result in out-of-order delivery.
	func() {
		h.mu.Lock()
		defer h.mu.Unlock()
		h.buf.Reset()
		err = h.handler.Handle(ctx, r)
	}()
	if err != nil {
		return err
	}

	h.mu.Lock()
	h.lastMessageSent = time.Now()
	h.mu.Unlock()

	params := &LoggingMessageParams{
		Logger: h.opts.LoggerName,
		Level:  slogLevelToMCP(r.Level),
		Data:   json.RawMessage(h.buf.Bytes()),
	}
	// We pass the argument context to Notify, even though slog.Handler.Handle's
	// documentation says not to.
	// In this case logging is a service to clients, not a means for debugging the
	// server, so we want to cancel the log message.
	return h.ss.LoggingMessage(ctx, params)
}


================================================
FILE: internal/mcp/mcp-repo-replace.txt
================================================
jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"==>"github.com/modelcontextprotocol/go-sdk/internal/jsonrpc2"
golang.org/x/tools/internal/xcontext==>github.com/modelcontextprotocol/go-sdk/internal/xcontext
golang.org/x/tools/internal/mcp/internal==>github.com/modelcontextprotocol/go-sdk/internal
golang.org/x/tools/internal/mcp/jsonschema==>github.com/modelcontextprotocol/go-sdk/jsonschema
golang.org/x/tools/internal/mcp/examples==>github.com/modelcontextprotocol/go-sdk/examples
golang.org/x/tools/internal/mcp/design==>github.com/modelcontextprotocol/go-sdk/design
golang.org/x/tools/internal/mcp==>github.com/modelcontextprotocol/go-sdk/mcp
governed by a BSD-style==>governed by an MIT-style
regex:Copyright (20\d\d) The Go Authors==>Copyright \1 The Go MCP SDK Authors


================================================
FILE: internal/mcp/mcp.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run generate.go
//go:generate ./internal/readme/build.sh

// The mcp package provides an SDK for writing model context protocol clients
// and servers.
//
// To get started, create either a [Client] or [Server], and connect it to a
// peer using a [Transport]. The diagram below illustrates how this works:
//
//	Client                                                   Server
//	 ⇅                          (jsonrpc2)                     ⇅
//	ClientSession ⇄ Client Transport ⇄ Server Transport ⇄ ServerSession
//
// A [Client] is an MCP client, which can be configured with various client
// capabilities. Clients may be connected to a [Server] instance
// using the [Client.Connect] method.
//
// Similarly, a [Server] is an MCP server, which can be configured with various
// server capabilities. Servers may be connected to one or more [Client]
// instances using the [Server.Connect] method, which creates a
// [ServerSession].
//
// A [Transport] connects a bidirectional [Connection] of jsonrpc2 messages. In
// practice, transports in the MCP spec are either client transports or
// server transports. For example, the [StdioTransport] is a server transport
// that communicates over stdin/stdout, and its counterpart is a
// [CommandTransport] that communicates with a subprocess over its
// stdin/stdout.
//
// Some transports may hide more complicated details, such as an
// [SSEClientTransport], which reads messages via server-sent events on a
// hanging GET request, and writes them to a POST endpoint. Users of this SDK
// may define their own custom Transports by implementing the [Transport]
// interface.
package mcp


================================================
FILE: internal/mcp/mcp_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/url"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

type hiParams struct {
	Name string
}

func sayHi(ctx context.Context, ss *ServerSession, params *CallToolParamsFor[hiParams]) (*CallToolResultFor[any], error) {
	if err := ss.Ping(ctx, nil); err != nil {
		return nil, fmt.Errorf("ping failed: %v", err)
	}
	return &CallToolResultFor[any]{Content: []*Content{NewTextContent("hi " + params.Arguments.Name)}}, nil
}

func TestEndToEnd(t *testing.T) {
	ctx := context.Background()
	var ct, st Transport = NewInMemoryTransports()

	// Channels to check if notification callbacks happened.
	notificationChans := map[string]chan int{}
	for _, name := range []string{"initialized", "roots", "tools", "prompts", "resources", "progress_server", "progress_client"} {
		notificationChans[name] = make(chan int, 1)
	}
	waitForNotification := func(t *testing.T, name string) {
		t.Helper()
		select {
		case <-notificationChans[name]:
		case <-time.After(time.Second):
			t.Fatalf("%s handler never called", name)
		}
	}

	sopts := &ServerOptions{
		InitializedHandler:      func(context.Context, *ServerSession, *InitializedParams) { notificationChans["initialized"] <- 0 },
		RootsListChangedHandler: func(context.Context, *ServerSession, *RootsListChangedParams) { notificationChans["roots"] <- 0 },
		ProgressNotificationHandler: func(context.Context, *ServerSession, *ProgressNotificationParams) {
			notificationChans["progress_server"] <- 0
		},
	}
	s := NewServer("testServer", "v1.0.0", sopts)
	add(tools, s.AddTools, "greet", "fail")
	add(prompts, s.AddPrompts, "code_review", "fail")
	add(resources, s.AddResources, "info.txt", "fail.txt")

	// Connect the server.
	ss, err := s.Connect(ctx, st)
	if err != nil {
		t.Fatal(err)
	}
	if got := slices.Collect(s.Sessions()); len(got) != 1 {
		t.Errorf("after connection, Clients() has length %d, want 1", len(got))
	}

	// Wait for the server to exit after the client closes its connection.
	var clientWG sync.WaitGroup
	clientWG.Add(1)
	go func() {
		if err := ss.Wait(); err != nil {
			t.Errorf("server failed: %v", err)
		}
		clientWG.Done()
	}()

	loggingMessages := make(chan *LoggingMessageParams, 100) // big enough for all logging
	opts := &ClientOptions{
		CreateMessageHandler: func(context.Context, *ClientSession, *CreateMessageParams) (*CreateMessageResult, error) {
			return &CreateMessageResult{Model: "aModel"}, nil
		},
		ToolListChangedHandler:     func(context.Context, *ClientSession, *ToolListChangedParams) { notificationChans["tools"] <- 0 },
		PromptListChangedHandler:   func(context.Context, *ClientSession, *PromptListChangedParams) { notificationChans["prompts"] <- 0 },
		ResourceListChangedHandler: func(context.Context, *ClientSession, *ResourceListChangedParams) { notificationChans["resources"] <- 0 },
		LoggingMessageHandler: func(_ context.Context, _ *ClientSession, lm *LoggingMessageParams) {
			loggingMessages <- lm
		},
		ProgressNotificationHandler: func(context.Context, *ClientSession, *ProgressNotificationParams) {
			notificationChans["progress_client"] <- 0
		},
	}
	c := NewClient("testClient", "v1.0.0", opts)
	rootAbs, err := filepath.Abs(filepath.FromSlash("testdata/files"))
	if err != nil {
		t.Fatal(err)
	}
	c.AddRoots(&Root{URI: "file://" + rootAbs})

	// Connect the client.
	cs, err := c.Connect(ctx, ct)
	if err != nil {
		t.Fatal(err)
	}

	waitForNotification(t, "initialized")
	if err := cs.Ping(ctx, nil); err != nil {
		t.Fatalf("ping failed: %v", err)
	}
	t.Run("prompts", func(t *testing.T) {
		res, err := cs.ListPrompts(ctx, nil)
		if err != nil {
			t.Fatalf("prompts/list failed: %v", err)
		}
		wantPrompts := []*Prompt{
			{
				Name:        "code_review",
				Description: "do a code review",
				Arguments:   []*PromptArgument{{Name: "Code", Required: true}},
			},
			{Name: "fail"},
		}
		if diff := cmp.Diff(wantPrompts, res.Prompts); diff != "" {
			t.Fatalf("prompts/list mismatch (-want +got):\n%s", diff)
		}

		gotReview, err := cs.GetPrompt(ctx, &GetPromptParams{Name: "code_review", Arguments: map[string]string{"Code": "1+1"}})
		if err != nil {
			t.Fatal(err)
		}
		wantReview := &GetPromptResult{
			Description: "Code review prompt",
			Messages: []*PromptMessage{{
				Content: NewTextContent("Please review the following code: 1+1"),
				Role:    "user",
			}},
		}
		if diff := cmp.Diff(wantReview, gotReview); diff != "" {
			t.Errorf("prompts/get 'code_review' mismatch (-want +got):\n%s", diff)
		}

		if _, err := cs.GetPrompt(ctx, &GetPromptParams{Name: "fail"}); err == nil || !strings.Contains(err.Error(), errTestFailure.Error()) {
			t.Errorf("fail returned unexpected error: got %v, want containing %v", err, errTestFailure)
		}

		s.AddPrompts(&ServerPrompt{Prompt: &Prompt{Name: "T"}})
		waitForNotification(t, "prompts")
		s.RemovePrompts("T")
		waitForNotification(t, "prompts")
	})

	t.Run("tools", func(t *testing.T) {
		res, err := cs.ListTools(ctx, nil)
		if err != nil {
			t.Errorf("tools/list failed: %v", err)
		}
		wantTools := []*Tool{
			{
				Name:        "fail",
				InputSchema: nil,
			},
			{
				Name:        "greet",
				Description: "say hi",
				InputSchema: &jsonschema.Schema{
					Type:     "object",
					Required: []string{"Name"},
					Properties: map[string]*jsonschema.Schema{
						"Name": {Type: "string"},
					},
					AdditionalProperties: falseSchema(),
				},
			},
		}
		if diff := cmp.Diff(wantTools, res.Tools, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
			t.Fatalf("tools/list mismatch (-want +got):\n%s", diff)
		}

		gotHi, err := cs.CallTool(ctx, &CallToolParams{
			Name:      "greet",
			Arguments: map[string]any{"name": "user"},
		})
		if err != nil {
			t.Fatal(err)
		}
		wantHi := &CallToolResult{
			Content: []*Content{{Type: "text", Text: "hi user"}},
		}
		if diff := cmp.Diff(wantHi, gotHi); diff != "" {
			t.Errorf("tools/call 'greet' mismatch (-want +got):\n%s", diff)
		}

		gotFail, err := cs.CallTool(ctx, &CallToolParams{
			Name:      "fail",
			Arguments: map[string]any{},
		})
		// Counter-intuitively, when a tool fails, we don't expect an RPC error for
		// call tool: instead, the failure is embedded in the result.
		if err != nil {
			t.Fatal(err)
		}
		wantFail := &CallToolResult{
			IsError: true,
			Content: []*Content{{Type: "text", Text: errTestFailure.Error()}},
		}
		if diff := cmp.Diff(wantFail, gotFail); diff != "" {
			t.Errorf("tools/call 'fail' mismatch (-want +got):\n%s", diff)
		}

		s.AddTools(&ServerTool{Tool: &Tool{Name: "T"}, Handler: nopHandler})
		waitForNotification(t, "tools")
		s.RemoveTools("T")
		waitForNotification(t, "tools")
	})

	t.Run("resources", func(t *testing.T) {
		if runtime.GOOS == "windows" {
			t.Skip("TODO: fix for Windows")
		}
		wantResources := []*Resource{resource2, resource1}
		lrres, err := cs.ListResources(ctx, nil)
		if err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(wantResources, lrres.Resources); diff != "" {
			t.Errorf("resources/list mismatch (-want, +got):\n%s", diff)
		}

		template := &ResourceTemplate{
			Name:        "rt",
			MIMEType:    "text/template",
			URITemplate: "file:///{+filename}", // the '+' means that filename can contain '/'
		}
		st := &ServerResourceTemplate{ResourceTemplate: template, Handler: readHandler}
		s.AddResourceTemplates(st)
		tres, err := cs.ListResourceTemplates(ctx, nil)
		if err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff([]*ResourceTemplate{template}, tres.ResourceTemplates); diff != "" {
			t.Errorf("resources/list mismatch (-want, +got):\n%s", diff)
		}

		for _, tt := range []struct {
			uri      string
			mimeType string // "": not found; "text/plain": resource; "text/template": template
			fail     bool   // non-nil error returned
		}{
			{"file:///info.txt", "text/plain", false},
			{"file:///fail.txt", "", false},
			{"file:///template.txt", "text/template", false},
			{"file:///../private.txt", "", true}, // not found: escaping disallowed
		} {
			rres, err := cs.ReadResource(ctx, &ReadResourceParams{URI: tt.uri})
			if err != nil {
				if code := errorCode(err); code == CodeResourceNotFound {
					if tt.mimeType != "" {
						t.Errorf("%s: not found but expected it to be", tt.uri)
					}
				} else if !tt.fail {
					t.Errorf("%s: unexpected error %v", tt.uri, err)
				}
			} else {
				if tt.fail {
					t.Errorf("%s: unexpected success", tt.uri)
				} else if g, w := len(rres.Contents), 1; g != w {
					t.Errorf("got %d contents, wanted %d", g, w)
				} else {
					c := rres.Contents[0]
					if got := c.URI; got != tt.uri {
						t.Errorf("got uri %q, want %q", got, tt.uri)
					}
					if got := c.MIMEType; got != tt.mimeType {
						t.Errorf("%s: got MIME type %q, want %q", tt.uri, got, tt.mimeType)
					}
				}
			}
		}

		s.AddResources(&ServerResource{Resource: &Resource{URI: "http://U"}})
		waitForNotification(t, "resources")
		s.RemoveResources("http://U")
		waitForNotification(t, "resources")
	})
	t.Run("roots", func(t *testing.T) {
		rootRes, err := ss.ListRoots(ctx, &ListRootsParams{})
		if err != nil {
			t.Fatal(err)
		}
		gotRoots := rootRes.Roots
		wantRoots := slices.Collect(c.roots.all())
		if diff := cmp.Diff(wantRoots, gotRoots); diff != "" {
			t.Errorf("roots/list mismatch (-want +got):\n%s", diff)
		}

		c.AddRoots(&Root{URI: "U"})
		waitForNotification(t, "roots")
		c.RemoveRoots("U")
		waitForNotification(t, "roots")
	})
	t.Run("sampling", func(t *testing.T) {
		// TODO: test that a client that doesn't have the handler returns CodeUnsupportedMethod.
		res, err := ss.CreateMessage(ctx, &CreateMessageParams{})
		if err != nil {
			t.Fatal(err)
		}
		if g, w := res.Model, "aModel"; g != w {
			t.Errorf("got %q, want %q", g, w)
		}
	})
	t.Run("logging", func(t *testing.T) {
		want := []*LoggingMessageParams{
			{
				Logger: "test",
				Level:  "warning",
				Data: map[string]any{
					"msg":     "first",
					"name":    "Pat",
					"logtest": true,
				},
			},
			{
				Logger: "test",
				Level:  "alert",
				Data: map[string]any{
					"msg":     "second",
					"count":   2.0,
					"logtest": true,
				},
			},
		}

		check := func(t *testing.T) {
			t.Helper()
			var got []*LoggingMessageParams
			// Read messages from this test until we've seen all we expect.
			for len(got) < len(want) {
				select {
				case p := <-loggingMessages:
					// Ignore logging from other tests.
					if m, ok := p.Data.(map[string]any); ok && m["logtest"] != nil {
						delete(m, "time") // remove time because it changes
						got = append(got, p)
					}
				case <-time.After(time.Second):
					t.Fatal("timed out waiting for log messages")
				}
			}
			if diff := cmp.Diff(want, got); diff != "" {
				t.Errorf("mismatch (-want, +got):\n%s", diff)
			}
		}

		t.Run("direct", func(t *testing.T) { // Use the LoggingMessage method directly.

			mustLog := func(level LoggingLevel, data any) {
				t.Helper()
				if err := ss.LoggingMessage(ctx, &LoggingMessageParams{
					Logger: "test",
					Level:  level,
					Data:   data,
				}); err != nil {
					t.Fatal(err)
				}
			}

			// Nothing should be logged until the client sets a level.
			mustLog("info", "before")
			if err := cs.SetLevel(ctx, &SetLevelParams{Level: "warning"}); err != nil {
				t.Fatal(err)
			}
			mustLog("warning", want[0].Data)
			mustLog("debug", "nope")    // below the level
			mustLog("info", "negative") // below the level
			mustLog("alert", want[1].Data)
			check(t)
		})

		t.Run("handler", func(t *testing.T) { // Use the slog handler.
			// We can't check the "before SetLevel" behavior because it's already been set.
			// Not a big deal: that check is in LoggingMessage anyway.
			logger := slog.New(NewLoggingHandler(ss, &LoggingHandlerOptions{LoggerName: "test"}))
			logger.Warn("first", "name", "Pat", "logtest", true)
			logger.Debug("nope")    // below the level
			logger.Info("negative") // below the level
			logger.Log(ctx, LevelAlert, "second", "count", 2, "logtest", true)
			check(t)
		})
	})
	t.Run("progress", func(t *testing.T) {
		ss.NotifyProgress(ctx, &ProgressNotificationParams{
			ProgressToken: "token-xyz",
			Message:       "progress update",
			Progress:      0.5,
			Total:         2,
		})
		waitForNotification(t, "progress_client")
		cs.NotifyProgress(ctx, &ProgressNotificationParams{
			ProgressToken: "token-abc",
			Message:       "progress update",
			Progress:      1,
			Total:         2,
		})
		waitForNotification(t, "progress_server")
	})

	// Disconnect.
	cs.Close()
	clientWG.Wait()

	// After disconnecting, neither client nor server should have any
	// connections.
	for range s.Sessions() {
		t.Errorf("unexpected client after disconnection")
	}
}

// Registry of values to be referenced in tests.
var (
	errTestFailure = errors.New("mcp failure")

	tools = map[string]*ServerTool{
		"greet": NewServerTool("greet", "say hi", sayHi),
		"fail": {
			Tool: &Tool{Name: "fail"},
			Handler: func(context.Context, *ServerSession, *CallToolParamsFor[map[string]any]) (*CallToolResult, error) {
				return nil, errTestFailure
			},
		},
	}

	prompts = map[string]*ServerPrompt{
		"code_review": {
			Prompt: &Prompt{
				Name:        "code_review",
				Description: "do a code review",
				Arguments:   []*PromptArgument{{Name: "Code", Required: true}},
			},
			Handler: func(_ context.Context, _ *ServerSession, params *GetPromptParams) (*GetPromptResult, error) {
				return &GetPromptResult{
					Description: "Code review prompt",
					Messages: []*PromptMessage{
						{Role: "user", Content: NewTextContent("Please review the following code: " + params.Arguments["Code"])},
					},
				}, nil
			},
		},
		"fail": {
			Prompt: &Prompt{Name: "fail"},
			Handler: func(_ context.Context, _ *ServerSession, _ *GetPromptParams) (*GetPromptResult, error) {
				return nil, errTestFailure
			},
		},
	}

	resource1 = &Resource{
		Name:     "public",
		MIMEType: "text/plain",
		URI:      "file:///info.txt",
	}
	resource2 = &Resource{
		Name:     "public", // names are not unique IDs
		MIMEType: "text/plain",
		URI:      "file:///fail.txt",
	}
	resource3 = &Resource{
		Name:     "info",
		MIMEType: "text/plain",
		URI:      "embedded:info",
	}
	readHandler = fileResourceHandler("testdata/files")
	resources   = map[string]*ServerResource{
		"info.txt": {resource1, readHandler},
		"fail.txt": {resource2, readHandler},
		"info":     {resource3, handleEmbeddedResource},
	}
)

var embeddedResources = map[string]string{
	"info": "This is the MCP test server.",
}

func handleEmbeddedResource(_ context.Context, _ *ServerSession, params *ReadResourceParams) (*ReadResourceResult, error) {
	u, err := url.Parse(params.URI)
	if err != nil {
		return nil, err
	}
	if u.Scheme != "embedded" {
		return nil, fmt.Errorf("wrong scheme: %q", u.Scheme)
	}
	key := u.Opaque
	text, ok := embeddedResources[key]
	if !ok {
		return nil, fmt.Errorf("no embedded resource named %q", key)
	}
	return &ReadResourceResult{
		Contents: []*ResourceContents{NewTextResourceContents(params.URI, "text/plain", text)},
	}, nil
}

// Add calls the given function to add the named features.
func add[T any](m map[string]T, add func(...T), names ...string) {
	for _, name := range names {
		feat, ok := m[name]
		if !ok {
			panic("missing feature " + name)
		}
		add(feat)
	}
}

// errorCode returns the code associated with err.
// If err is nil, it returns 0.
// If there is no code, it returns -1.
func errorCode(err error) int64 {
	if err == nil {
		return 0
	}
	var werr *jsonrpc2.WireError
	if errors.As(err, &werr) {
		return werr.Code
	}
	return -1
}

// basicConnection returns a new basic client-server connection configured with
// the provided tools.
//
// The caller should cancel either the client connection or server connection
// when the connections are no longer needed.
func basicConnection(t *testing.T, tools ...*ServerTool) (*ServerSession, *ClientSession) {
	t.Helper()

	ctx := context.Background()
	ct, st := NewInMemoryTransports()

	s := NewServer("testServer", "v1.0.0", nil)

	// The 'greet' tool says hi.
	s.AddTools(tools...)
	ss, err := s.Connect(ctx, st)
	if err != nil {
		t.Fatal(err)
	}

	c := NewClient("testClient", "v1.0.0", nil)
	cs, err := c.Connect(ctx, ct)
	if err != nil {
		t.Fatal(err)
	}
	return ss, cs
}

func TestServerClosing(t *testing.T) {
	cc, cs := basicConnection(t, NewServerTool("greet", "say hi", sayHi))
	defer cs.Close()

	ctx := context.Background()
	var wg sync.WaitGroup
	wg.Add(1)
	go func() {
		if err := cs.Wait(); err != nil {
			t.Errorf("server connection failed: %v", err)
		}
		wg.Done()
	}()
	if _, err := cs.CallTool(ctx, &CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "user"},
	}); err != nil {
		t.Fatalf("after connecting: %v", err)
	}
	cc.Close()
	wg.Wait()
	if _, err := cs.CallTool(ctx, &CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "user"},
	}); !errors.Is(err, ErrConnectionClosed) {
		t.Errorf("after disconnection, got error %v, want EOF", err)
	}
}

func TestBatching(t *testing.T) {
	ctx := context.Background()
	ct, st := NewInMemoryTransports()

	s := NewServer("testServer", "v1.0.0", nil)
	_, err := s.Connect(ctx, st)
	if err != nil {
		t.Fatal(err)
	}

	c := NewClient("testClient", "v1.0.0", nil)
	// TODO: this test is broken, because increasing the batch size here causes
	// 'initialize' to block. Therefore, we can only test with a size of 1.
	// Since batching is being removed, we can probably just delete this.
	const batchSize = 1
	cs, err := c.Connect(ctx, ct)
	if err != nil {
		t.Fatal(err)
	}
	defer cs.Close()

	errs := make(chan error, batchSize)
	for i := range batchSize {
		go func() {
			_, err := cs.ListTools(ctx, nil)
			errs <- err
		}()
		time.Sleep(2 * time.Millisecond)
		if i < batchSize-1 {
			select {
			case <-errs:
				t.Errorf("ListTools: unexpected result for incomplete batch: %v", err)
			default:
			}
		}
	}
}

func TestCancellation(t *testing.T) {
	var (
		start     = make(chan struct{})
		cancelled = make(chan struct{}, 1) // don't block the request
	)

	slowRequest := func(ctx context.Context, cc *ServerSession, params *CallToolParamsFor[map[string]any]) (*CallToolResult, error) {
		start <- struct{}{}
		select {
		case <-ctx.Done():
			cancelled <- struct{}{}
		case <-time.After(5 * time.Second):
			return nil, nil
		}
		return nil, nil
	}
	st := &ServerTool{
		Tool:    &Tool{Name: "slow"},
		Handler: slowRequest,
	}
	_, cs := basicConnection(t, st)
	defer cs.Close()

	ctx, cancel := context.WithCancel(context.Background())
	go cs.CallTool(ctx, &CallToolParams{Name: "slow"})
	<-start
	cancel()
	select {
	case <-cancelled:
	case <-time.After(5 * time.Second):
		t.Fatal("timeout waiting for cancellation")
	}
}

func TestMiddleware(t *testing.T) {
	ctx := context.Background()
	ct, st := NewInMemoryTransports()

	s := NewServer("testServer", "v1.0.0", nil)
	ss, err := s.Connect(ctx, st)
	if err != nil {
		t.Fatal(err)
	}
	// Wait for the server to exit after the client closes its connection.
	var clientWG sync.WaitGroup
	clientWG.Add(1)
	go func() {
		if err := ss.Wait(); err != nil {
			t.Errorf("server failed: %v", err)
		}
		clientWG.Done()
	}()

	var sbuf, cbuf bytes.Buffer
	sbuf.WriteByte('\n')
	cbuf.WriteByte('\n')

	// "1" is the outer middleware layer, called first; then "2" is called, and finally
	// the default dispatcher.
	s.AddSendingMiddleware(traceCalls[*ServerSession](&sbuf, "S1"), traceCalls[*ServerSession](&sbuf, "S2"))
	s.AddReceivingMiddleware(traceCalls[*ServerSession](&sbuf, "R1"), traceCalls[*ServerSession](&sbuf, "R2"))

	c := NewClient("testClient", "v1.0.0", nil)
	c.AddSendingMiddleware(traceCalls[*ClientSession](&cbuf, "S1"), traceCalls[*ClientSession](&cbuf, "S2"))
	c.AddReceivingMiddleware(traceCalls[*ClientSession](&cbuf, "R1"), traceCalls[*ClientSession](&cbuf, "R2"))

	cs, err := c.Connect(ctx, ct)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := cs.ListTools(ctx, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := ss.ListRoots(ctx, nil); err != nil {
		t.Fatal(err)
	}

	wantServer := `
R1 >initialize
R2 >initialize
R2 <initialize
R1 <initialize
R1 >notifications/initialized
R2 >notifications/initialized
R2 <notifications/initialized
R1 <notifications/initialized
R1 >tools/list
R2 >tools/list
R2 <tools/list
R1 <tools/list
S1 >roots/list
S2 >roots/list
S2 <roots/list
S1 <roots/list
`
	if diff := cmp.Diff(wantServer, sbuf.String()); diff != "" {
		t.Errorf("server mismatch (-want, +got):\n%s", diff)
	}

	wantClient := `
S1 >initialize
S2 >initialize
S2 <initialize
S1 <initialize
S1 >notifications/initialized
S2 >notifications/initialized
S2 <notifications/initialized
S1 <notifications/initialized
S1 >tools/list
S2 >tools/list
S2 <tools/list
S1 <tools/list
R1 >roots/list
R2 >roots/list
R2 <roots/list
R1 <roots/list
`
	if diff := cmp.Diff(wantClient, cbuf.String()); diff != "" {
		t.Errorf("client mismatch (-want, +got):\n%s", diff)
	}
}

type safeBuffer struct {
	mu  sync.Mutex
	buf bytes.Buffer
}

func (b *safeBuffer) Write(data []byte) (int, error) {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buf.Write(data)
}

func (b *safeBuffer) Bytes() []byte {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buf.Bytes()
}

func TestNoJSONNull(t *testing.T) {
	ctx := context.Background()
	var ct, st Transport = NewInMemoryTransports()

	// Collect logs, to sanity check that we don't write JSON null anywhere.
	var logbuf safeBuffer
	ct = NewLoggingTransport(ct, &logbuf)

	s := NewServer("testServer", "v1.0.0", nil)
	ss, err := s.Connect(ctx, st)
	if err != nil {
		t.Fatal(err)
	}

	c := NewClient("testClient", "v1.0.0", nil)
	cs, err := c.Connect(ctx, ct)
	if err != nil {
		t.Fatal(err)
	}
	if _, err := cs.ListTools(ctx, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := cs.ListPrompts(ctx, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := cs.ListResources(ctx, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := cs.ListResourceTemplates(ctx, nil); err != nil {
		t.Fatal(err)
	}
	if _, err := ss.ListRoots(ctx, nil); err != nil {
		t.Fatal(err)
	}

	cs.Close()
	ss.Wait()

	logs := logbuf.Bytes()
	if i := bytes.Index(logs, []byte("null")); i >= 0 {
		start := max(i-20, 0)
		end := min(i+20, len(logs))
		t.Errorf("conformance violation: MCP logs contain JSON null: %s", "..."+string(logs[start:end])+"...")
	}
}

// traceCalls creates a middleware function that prints the method before and after each call
// with the given prefix.
func traceCalls[S Session](w io.Writer, prefix string) Middleware[S] {
	return func(h MethodHandler[S]) MethodHandler[S] {
		return func(ctx context.Context, sess S, method string, params Params) (Result, error) {
			fmt.Fprintf(w, "%s >%s\n", prefix, method)
			defer fmt.Fprintf(w, "%s <%s\n", prefix, method)
			return h(ctx, sess, method, params)
		}
	}
}

// A function, because schemas must form a tree (they have hidden state).
func falseSchema() *jsonschema.Schema { return &jsonschema.Schema{Not: &jsonschema.Schema{}} }

func nopHandler(context.Context, *ServerSession, *CallToolParamsFor[map[string]any]) (*CallToolResult, error) {
	return nil, nil
}


================================================
FILE: internal/mcp/prompt.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
)

// A PromptHandler handles a call to prompts/get.
type PromptHandler func(context.Context, *ServerSession, *GetPromptParams) (*GetPromptResult, error)

// A Prompt is a prompt definition bound to a prompt handler.
type ServerPrompt struct {
	Prompt  *Prompt
	Handler PromptHandler
}


================================================
FILE: internal/mcp/protocol.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package mcp

import (
	"golang.org/x/tools/internal/mcp/jsonschema"
)

// Optional annotations for the client. The client can use annotations to inform
// how objects are used or displayed
type Annotations struct {
	// Describes who the intended customer of this object or data is.
	//
	// It can include multiple entries to indicate content useful for multiple
	// audiences (e.g., `["user", "assistant"]`).
	Audience []Role `json:"audience,omitempty"`
	// Describes how important this data is for operating the server.
	//
	// A value of 1 means "most important," and indicates that the data is
	// effectively required, while 0 means "least important," and indicates that the
	// data is entirely optional.
	Priority float64 `json:"priority,omitempty"`
}

type CallToolParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta      Meta   `json:"_meta,omitempty"`
	Arguments any    `json:"arguments,omitempty"`
	Name      string `json:"name"`
}

func (x *CallToolParams) GetMeta() *Meta { return &x.Meta }

type CallToolParamsFor[In any] struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta      Meta   `json:"_meta,omitempty"`
	Arguments In     `json:"arguments,omitempty"`
	Name      string `json:"name"`
}

func (x *CallToolParamsFor[In]) GetMeta() *Meta { return &x.Meta }

// The server's response to a tool call.
//
// Any errors that originate from the tool SHOULD be reported inside the result
// object, with `isError` set to true, _not_ as an MCP protocol-level error
// response. Otherwise, the LLM would not be able to see that an error occurred
// and self-correct.
//
// However, any errors in _finding_ the tool, an error indicating that the
// server does not support tool calls, or any other exceptional conditions,
// should be reported as an MCP error response.
type CallToolResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta    Meta       `json:"_meta,omitempty"`
	Content []*Content `json:"content"`
	// Whether the tool call ended in an error.
	//
	// If not set, this is assumed to be false (the call was successful).
	IsError bool `json:"isError,omitempty"`
}

func (x *CallToolResult) GetMeta() *Meta { return &x.Meta }

type CallToolResultFor[Out any] struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta    Meta       `json:"_meta,omitempty"`
	Content []*Content `json:"content"`
	// Whether the tool call ended in an error.
	//
	// If not set, this is assumed to be false (the call was successful).
	IsError bool `json:"isError,omitempty"`
}

func (x *CallToolResultFor[Out]) GetMeta() *Meta { return &x.Meta }

type CancelledParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An optional string describing the reason for the cancellation. This MAY be
	// logged or presented to the user.
	Reason string `json:"reason,omitempty"`
	// The ID of the request to cancel.
	//
	// This MUST correspond to the ID of a request previously issued in the same
	// direction.
	RequestID any `json:"requestId"`
}

func (x *CancelledParams) GetMeta() *Meta { return &x.Meta }

// Capabilities a client may support. Known capabilities are defined here, in
// this schema, but this is not a closed set: any client can define its own,
// additional capabilities.
type ClientCapabilities struct {
	// Experimental, non-standard capabilities that the client supports.
	Experimental map[string]struct {
	} `json:"experimental,omitempty"`
	// Present if the client supports listing roots.
	Roots struct {
		// Whether the client supports notifications for changes to the roots list.
		ListChanged bool `json:"listChanged,omitempty"`
	} `json:"roots,omitempty"`
	// Present if the client supports sampling from an LLM.
	Sampling *SamplingCapabilities `json:"sampling,omitempty"`
}

type CreateMessageParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// A request to include context from one or more MCP servers (including the
	// caller), to be attached to the prompt. The client MAY ignore this request.
	IncludeContext string `json:"includeContext,omitempty"`
	// The maximum number of tokens to sample, as requested by the server. The
	// client MAY choose to sample fewer tokens than requested.
	MaxTokens int64              `json:"maxTokens"`
	Messages  []*SamplingMessage `json:"messages"`
	// Optional metadata to pass through to the LLM provider. The format of this
	// metadata is provider-specific.
	Metadata struct {
	} `json:"metadata,omitempty"`
	// The server's preferences for which model to select. The client MAY ignore
	// these preferences.
	ModelPreferences *ModelPreferences `json:"modelPreferences,omitempty"`
	StopSequences    []string          `json:"stopSequences,omitempty"`
	// An optional system prompt the server wants to use for sampling. The client
	// MAY modify or omit this prompt.
	SystemPrompt string  `json:"systemPrompt,omitempty"`
	Temperature  float64 `json:"temperature,omitempty"`
}

func (x *CreateMessageParams) GetMeta() *Meta { return &x.Meta }

// The client's response to a sampling/create_message request from the server.
// The client should inform the user before returning the sampled message, to
// allow them to inspect the response (human in the loop) and decide whether to
// allow the server to see it.
type CreateMessageResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta    Meta     `json:"_meta,omitempty"`
	Content *Content `json:"content"`
	// The name of the model that generated the message.
	Model string `json:"model"`
	Role  Role   `json:"role"`
	// The reason why sampling stopped, if known.
	StopReason string `json:"stopReason,omitempty"`
}

func (x *CreateMessageResult) GetMeta() *Meta { return &x.Meta }

type GetPromptParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// Arguments to use for templating the prompt.
	Arguments map[string]string `json:"arguments,omitempty"`
	// The name of the prompt or prompt template.
	Name string `json:"name"`
}

func (x *GetPromptParams) GetMeta() *Meta { return &x.Meta }

// The server's response to a prompts/get request from the client.
type GetPromptResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An optional description for the prompt.
	Description string           `json:"description,omitempty"`
	Messages    []*PromptMessage `json:"messages"`
}

func (x *GetPromptResult) GetMeta() *Meta { return &x.Meta }

type InitializeParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta         Meta                `json:"_meta,omitempty"`
	Capabilities *ClientCapabilities `json:"capabilities"`
	ClientInfo   *implementation     `json:"clientInfo"`
	// The latest version of the Model Context Protocol that the client supports.
	// The client MAY decide to support older versions as well.
	ProtocolVersion string `json:"protocolVersion"`
}

func (x *InitializeParams) GetMeta() *Meta { return &x.Meta }

// After receiving an initialize request from the client, the server sends this
// response.
type InitializeResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta         Meta                `json:"_meta,omitempty"`
	Capabilities *serverCapabilities `json:"capabilities"`
	// Instructions describing how to use the server and its features.
	//
	// This can be used by clients to improve the LLM's understanding of available
	// tools, resources, etc. It can be thought of like a "hint" to the model. For
	// example, this information MAY be added to the system prompt.
	Instructions string `json:"instructions,omitempty"`
	// The version of the Model Context Protocol that the server wants to use. This
	// may not match the version that the client requested. If the client cannot
	// support this version, it MUST disconnect.
	ProtocolVersion string          `json:"protocolVersion"`
	ServerInfo      *implementation `json:"serverInfo"`
}

func (x *InitializeResult) GetMeta() *Meta { return &x.Meta }

type InitializedParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *InitializedParams) GetMeta() *Meta { return &x.Meta }

type ListPromptsParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the current pagination position. If provided,
	// the server should return results starting after this cursor.
	Cursor string `json:"cursor,omitempty"`
}

func (x *ListPromptsParams) GetMeta() *Meta     { return &x.Meta }
func (x *ListPromptsParams) cursorPtr() *string { return &x.Cursor }

// The server's response to a prompts/list request from the client.
type ListPromptsResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the pagination position after the last returned
	// result. If present, there may be more results available.
	NextCursor string    `json:"nextCursor,omitempty"`
	Prompts    []*Prompt `json:"prompts"`
}

func (x *ListPromptsResult) GetMeta() *Meta         { return &x.Meta }
func (x *ListPromptsResult) nextCursorPtr() *string { return &x.NextCursor }

type ListResourceTemplatesParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the current pagination position. If provided,
	// the server should return results starting after this cursor.
	Cursor string `json:"cursor,omitempty"`
}

func (x *ListResourceTemplatesParams) GetMeta() *Meta     { return &x.Meta }
func (x *ListResourceTemplatesParams) cursorPtr() *string { return &x.Cursor }

// The server's response to a resources/templates/list request from the client.
type ListResourceTemplatesResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the pagination position after the last returned
	// result. If present, there may be more results available.
	NextCursor        string              `json:"nextCursor,omitempty"`
	ResourceTemplates []*ResourceTemplate `json:"resourceTemplates"`
}

func (x *ListResourceTemplatesResult) GetMeta() *Meta         { return &x.Meta }
func (x *ListResourceTemplatesResult) nextCursorPtr() *string { return &x.NextCursor }

type ListResourcesParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the current pagination position. If provided,
	// the server should return results starting after this cursor.
	Cursor string `json:"cursor,omitempty"`
}

func (x *ListResourcesParams) GetMeta() *Meta     { return &x.Meta }
func (x *ListResourcesParams) cursorPtr() *string { return &x.Cursor }

// The server's response to a resources/list request from the client.
type ListResourcesResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the pagination position after the last returned
	// result. If present, there may be more results available.
	NextCursor string      `json:"nextCursor,omitempty"`
	Resources  []*Resource `json:"resources"`
}

func (x *ListResourcesResult) GetMeta() *Meta         { return &x.Meta }
func (x *ListResourcesResult) nextCursorPtr() *string { return &x.NextCursor }

type ListRootsParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *ListRootsParams) GetMeta() *Meta { return &x.Meta }

// The client's response to a roots/list request from the server. This result
// contains an array of Root objects, each representing a root directory or file
// that the server can operate on.
type ListRootsResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta  Meta    `json:"_meta,omitempty"`
	Roots []*Root `json:"roots"`
}

func (x *ListRootsResult) GetMeta() *Meta { return &x.Meta }

type ListToolsParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the current pagination position. If provided,
	// the server should return results starting after this cursor.
	Cursor string `json:"cursor,omitempty"`
}

func (x *ListToolsParams) GetMeta() *Meta     { return &x.Meta }
func (x *ListToolsParams) cursorPtr() *string { return &x.Cursor }

// The server's response to a tools/list request from the client.
type ListToolsResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An opaque token representing the pagination position after the last returned
	// result. If present, there may be more results available.
	NextCursor string  `json:"nextCursor,omitempty"`
	Tools      []*Tool `json:"tools"`
}

func (x *ListToolsResult) GetMeta() *Meta         { return &x.Meta }
func (x *ListToolsResult) nextCursorPtr() *string { return &x.NextCursor }

// The severity of a log message.
//
// These map to syslog message severities, as specified in RFC-5424:
// https://datatracker.ietf.org/doc/html/rfc5424#section-6.2.1
type LoggingLevel string

type LoggingMessageParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// The data to be logged, such as a string message or an object. Any JSON
	// serializable type is allowed here.
	Data any `json:"data"`
	// The severity of this log message.
	Level LoggingLevel `json:"level"`
	// An optional name of the logger issuing this message.
	Logger string `json:"logger,omitempty"`
}

func (x *LoggingMessageParams) GetMeta() *Meta { return &x.Meta }

// Hints to use for model selection.
//
// Keys not declared here are currently left unspecified by the spec and are up
// to the client to interpret.
type ModelHint struct {
	// A hint for a model name.
	//
	// The client SHOULD treat this as a substring of a model name; for example: -
	// `claude-3-5-sonnet` should match `claude-3-5-sonnet-20241022` - `sonnet`
	// should match `claude-3-5-sonnet-20241022`, `claude-3-sonnet-20240229`, etc. -
	// `claude` should match any Claude model
	//
	// The client MAY also map the string to a different provider's model name or a
	// different model family, as long as it fills a similar niche; for example: -
	// `gemini-1.5-flash` could match `claude-3-haiku-20240307`
	Name string `json:"name,omitempty"`
}

// The server's preferences for model selection, requested of the client during
// sampling.
//
// Because LLMs can vary along multiple dimensions, choosing the "best" model is
// rarely straightforward. Different models excel in different areas—some are
// faster but less capable, others are more capable but more expensive, and so
// on. This interface allows servers to express their priorities across multiple
// dimensions to help clients make an appropriate selection for their use case.
//
// These preferences are always advisory. The client MAY ignore them. It is also
// up to the client to decide how to interpret these preferences and how to
// balance them against other considerations.
type ModelPreferences struct {
	// How much to prioritize cost when selecting a model. A value of 0 means cost
	// is not important, while a value of 1 means cost is the most important factor.
	CostPriority float64 `json:"costPriority,omitempty"`
	// Optional hints to use for model selection.
	//
	// If multiple hints are specified, the client MUST evaluate them in order (such
	// that the first match is taken).
	//
	// The client SHOULD prioritize these hints over the numeric priorities, but MAY
	// still use the priorities to select from ambiguous matches.
	Hints []*ModelHint `json:"hints,omitempty"`
	// How much to prioritize intelligence and capabilities when selecting a model.
	// A value of 0 means intelligence is not important, while a value of 1 means
	// intelligence is the most important factor.
	IntelligencePriority float64 `json:"intelligencePriority,omitempty"`
	// How much to prioritize sampling speed (latency) when selecting a model. A
	// value of 0 means speed is not important, while a value of 1 means speed is
	// the most important factor.
	SpeedPriority float64 `json:"speedPriority,omitempty"`
}

type PingParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *PingParams) GetMeta() *Meta { return &x.Meta }

type ProgressNotificationParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// An optional message describing the current progress.
	Message string `json:"message,omitempty"`
	// The progress thus far. This should increase every time progress is made, even
	// if the total is unknown.
	Progress float64 `json:"progress"`
	// The progress token which was given in the initial request, used to associate
	// this notification with the request that is proceeding.
	ProgressToken any `json:"progressToken"`
	// Total number of items to process (or total progress required), if known.
	Total float64 `json:"total,omitempty"`
}

func (x *ProgressNotificationParams) GetMeta() *Meta { return &x.Meta }

// A prompt or prompt template that the server offers.
type Prompt struct {
	// A list of arguments to use for templating the prompt.
	Arguments []*PromptArgument `json:"arguments,omitempty"`
	// An optional description of what this prompt provides
	Description string `json:"description,omitempty"`
	// The name of the prompt or prompt template.
	Name string `json:"name"`
}

// Describes an argument that a prompt can accept.
type PromptArgument struct {
	// A human-readable description of the argument.
	Description string `json:"description,omitempty"`
	// The name of the argument.
	Name string `json:"name"`
	// Whether this argument must be provided.
	Required bool `json:"required,omitempty"`
}

type PromptListChangedParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *PromptListChangedParams) GetMeta() *Meta { return &x.Meta }

// Describes a message returned as part of a prompt.
//
// This is similar to `SamplingMessage`, but also supports the embedding of
// resources from the MCP server.
type PromptMessage struct {
	Content *Content `json:"content"`
	Role    Role     `json:"role"`
}

type ReadResourceParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// The URI of the resource to read. The URI can use any protocol; it is up to
	// the server how to interpret it.
	URI string `json:"uri"`
}

func (x *ReadResourceParams) GetMeta() *Meta { return &x.Meta }

// The server's response to a resources/read request from the client.
type ReadResourceResult struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta     Meta                `json:"_meta,omitempty"`
	Contents []*ResourceContents `json:"contents"`
}

func (x *ReadResourceResult) GetMeta() *Meta { return &x.Meta }

// A known resource that the server is capable of reading.
type Resource struct {
	// Optional annotations for the client.
	Annotations *Annotations `json:"annotations,omitempty"`
	// A description of what this resource represents.
	//
	// This can be used by clients to improve the LLM's understanding of available
	// resources. It can be thought of like a "hint" to the model.
	Description string `json:"description,omitempty"`
	// The MIME type of this resource, if known.
	MIMEType string `json:"mimeType,omitempty"`
	// A human-readable name for this resource.
	//
	// This can be used by clients to populate UI elements.
	Name string `json:"name"`
	// The size of the raw resource content, in bytes (i.e., before base64 encoding
	// or any tokenization), if known.
	//
	// This can be used by Hosts to display file sizes and estimate context window
	// usage.
	Size int64 `json:"size,omitempty"`
	// The URI of this resource.
	URI string `json:"uri"`
}

type ResourceListChangedParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *ResourceListChangedParams) GetMeta() *Meta { return &x.Meta }

// A template description for resources available on the server.
type ResourceTemplate struct {
	// Optional annotations for the client.
	Annotations *Annotations `json:"annotations,omitempty"`
	// A description of what this template is for.
	//
	// This can be used by clients to improve the LLM's understanding of available
	// resources. It can be thought of like a "hint" to the model.
	Description string `json:"description,omitempty"`
	// The MIME type for all resources that match this template. This should only be
	// included if all resources matching this template have the same type.
	MIMEType string `json:"mimeType,omitempty"`
	// A human-readable name for the type of resource this template refers to.
	//
	// This can be used by clients to populate UI elements.
	Name string `json:"name"`
	// A URI template (according to RFC 6570) that can be used to construct resource
	// URIs.
	URITemplate string `json:"uriTemplate"`
}

// The sender or recipient of messages and data in a conversation.
type Role string

// Represents a root directory or file that the server can operate on.
type Root struct {
	// An optional name for the root. This can be used to provide a human-readable
	// identifier for the root, which may be useful for display purposes or for
	// referencing the root in other parts of the application.
	Name string `json:"name,omitempty"`
	// The URI identifying the root. This *must* start with file:// for now. This
	// restriction may be relaxed in future versions of the protocol to allow other
	// URI schemes.
	URI string `json:"uri"`
}

type RootsListChangedParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *RootsListChangedParams) GetMeta() *Meta { return &x.Meta }

// Present if the client supports sampling from an LLM.
type SamplingCapabilities struct {
}

// Describes a message issued to or received from an LLM API.
type SamplingMessage struct {
	Content *Content `json:"content"`
	Role    Role     `json:"role"`
}

type SetLevelParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
	// The level of logging that the client wants to receive from the server. The
	// server should send all logs at this level and higher (i.e., more severe) to
	// the client as notifications/message.
	Level LoggingLevel `json:"level"`
}

func (x *SetLevelParams) GetMeta() *Meta { return &x.Meta }

// Definition for a tool the client can call.
type Tool struct {
	// Optional additional tool information.
	Annotations *ToolAnnotations `json:"annotations,omitempty"`
	// A human-readable description of the tool.
	//
	// This can be used by clients to improve the LLM's understanding of available
	// tools. It can be thought of like a "hint" to the model.
	Description string `json:"description,omitempty"`
	// A JSON Schema object defining the expected parameters for the tool.
	InputSchema *jsonschema.Schema `json:"inputSchema"`
	// The name of the tool.
	Name string `json:"name"`
}

// Additional properties describing a Tool to clients.
//
// NOTE: all properties in ToolAnnotations are **hints**. They are not
// guaranteed to provide a faithful description of tool behavior (including
// descriptive properties like `title`).
//
// Clients should never make tool use decisions based on ToolAnnotations
// received from untrusted servers.
type ToolAnnotations struct {
	// If true, the tool may perform destructive updates to its environment. If
	// false, the tool performs only additive updates.
	//
	// (This property is meaningful only when `readOnlyHint == false`)
	//
	// Default: true
	DestructiveHint bool `json:"destructiveHint,omitempty"`
	// If true, calling the tool repeatedly with the same arguments will have no
	// additional effect on the its environment.
	//
	// (This property is meaningful only when `readOnlyHint == false`)
	//
	// Default: false
	IdempotentHint bool `json:"idempotentHint,omitempty"`
	// If true, this tool may interact with an "open world" of external entities. If
	// false, the tool's domain of interaction is closed. For example, the world of
	// a web search tool is open, whereas that of a memory tool is not.
	//
	// Default: true
	OpenWorldHint bool `json:"openWorldHint,omitempty"`
	// If true, the tool does not modify its environment.
	//
	// Default: false
	ReadOnlyHint bool `json:"readOnlyHint,omitempty"`
	// A human-readable title for the tool.
	Title string `json:"title,omitempty"`
}

type ToolListChangedParams struct {
	// This property is reserved by the protocol to allow clients and servers to
	// attach additional metadata to their responses.
	Meta Meta `json:"_meta,omitempty"`
}

func (x *ToolListChangedParams) GetMeta() *Meta { return &x.Meta }

// Describes the name and version of an MCP implementation.
type implementation struct {
	Name    string `json:"name"`
	Version string `json:"version"`
}

// Present if the server supports sending log messages to the client.
type loggingCapabilities struct {
}

// Present if the server offers any prompt templates.
type promptCapabilities struct {
	// Whether this server supports notifications for changes to the prompt list.
	ListChanged bool `json:"listChanged,omitempty"`
}

// Present if the server offers any resources to read.
type resourceCapabilities struct {
	// Whether this server supports notifications for changes to the resource list.
	ListChanged bool `json:"listChanged,omitempty"`
	// Whether this server supports subscribing to resource updates.
	Subscribe bool `json:"subscribe,omitempty"`
}

// Capabilities that a server may support. Known capabilities are defined here,
// in this schema, but this is not a closed set: any server can define its own,
// additional capabilities.
type serverCapabilities struct {
	// Present if the server supports argument autocompletion suggestions.
	Completions struct {
	} `json:"completions,omitempty"`
	// Experimental, non-standard capabilities that the server supports.
	Experimental map[string]struct {
	} `json:"experimental,omitempty"`
	// Present if the server supports sending log messages to the client.
	Logging *loggingCapabilities `json:"logging,omitempty"`
	// Present if the server offers any prompt templates.
	Prompts *promptCapabilities `json:"prompts,omitempty"`
	// Present if the server offers any resources to read.
	Resources *resourceCapabilities `json:"resources,omitempty"`
	// Present if the server offers any tools to call.
	Tools *toolCapabilities `json:"tools,omitempty"`
}

// Present if the server offers any tools to call.
type toolCapabilities struct {
	// Whether this server supports notifications for changes to the tool list.
	ListChanged bool `json:"listChanged,omitempty"`
}

const (
	methodCallTool                  = "tools/call"
	notificationCancelled           = "notifications/cancelled"
	methodComplete                  = "completion/complete"
	methodCreateMessage             = "sampling/createMessage"
	methodGetPrompt                 = "prompts/get"
	methodInitialize                = "initialize"
	notificationInitialized         = "notifications/initialized"
	methodListPrompts               = "prompts/list"
	methodListResourceTemplates     = "resources/templates/list"
	methodListResources             = "resources/list"
	methodListRoots                 = "roots/list"
	methodListTools                 = "tools/list"
	notificationLoggingMessage      = "notifications/message"
	methodPing                      = "ping"
	notificationProgress            = "notifications/progress"
	notificationPromptListChanged   = "notifications/prompts/list_changed"
	methodReadResource              = "resources/read"
	notificationResourceListChanged = "notifications/resources/list_changed"
	notificationResourceUpdated     = "notifications/resources/updated"
	notificationRootsListChanged    = "notifications/roots/list_changed"
	methodSetLevel                  = "logging/setLevel"
	methodSubscribe                 = "resources/subscribe"
	notificationToolListChanged     = "notifications/tools/list_changed"
	methodUnsubscribe               = "resources/unsubscribe"
)


================================================
FILE: internal/mcp/resource.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/url"
	"os"
	"path/filepath"
	"regexp"
	"strings"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/mcp/internal/util"
)

// A ServerResource associates a Resource with its handler.
type ServerResource struct {
	Resource *Resource
	Handler  ResourceHandler
}

// A ServerResourceTemplate associates a ResourceTemplate with its handler.
type ServerResourceTemplate struct {
	ResourceTemplate *ResourceTemplate
	Handler          ResourceHandler
}

// A ResourceHandler is a function that reads a resource.
// It will be called when the client calls [ClientSession.ReadResource].
// If it cannot find the resource, it should return the result of calling [ResourceNotFoundError].
type ResourceHandler func(context.Context, *ServerSession, *ReadResourceParams) (*ReadResourceResult, error)

// ResourceNotFoundError returns an error indicating that a resource being read could
// not be found.
func ResourceNotFoundError(uri string) error {
	return &jsonrpc2.WireError{
		Code:    CodeResourceNotFound,
		Message: "Resource not found",
		Data:    json.RawMessage(fmt.Sprintf(`{"uri":%q}`, uri)),
	}
}

// readFileResource reads from the filesystem at a URI relative to dirFilepath, respecting
// the roots.
// dirFilepath and rootFilepaths are absolute filesystem paths.
func readFileResource(rawURI, dirFilepath string, rootFilepaths []string) ([]byte, error) {
	uriFilepath, err := computeURIFilepath(rawURI, dirFilepath, rootFilepaths)
	if err != nil {
		return nil, err
	}

	var data []byte
	err = withFile(dirFilepath, uriFilepath, func(f *os.File) error {
		var err error
		data, err = io.ReadAll(f)
		return err
	})
	if os.IsNotExist(err) {
		err = ResourceNotFoundError(rawURI)
	}
	return data, err
}

// withFile calls f on the file at join(dir, rel),
// protecting against path traversal attacks.
func withFile(dir, rel string, f func(*os.File) error) (err error) {
	r, err := os.OpenRoot(dir)
	if err != nil {
		return err
	}
	defer r.Close()
	file, err := r.Open(rel)
	if err != nil {
		return err
	}
	// Record error, in case f writes.
	defer func() { err = errors.Join(err, file.Close()) }()
	return f(file)
}

// computeURIFilepath returns a path relative to dirFilepath.
// The dirFilepath and rootFilepaths are absolute file paths.
func computeURIFilepath(rawURI, dirFilepath string, rootFilepaths []string) (string, error) {
	// We use "file path" to mean a filesystem path.
	uri, err := url.Parse(rawURI)
	if err != nil {
		return "", err
	}
	if uri.Scheme != "file" {
		return "", fmt.Errorf("URI is not a file: %s", uri)
	}
	if uri.Path == "" {
		// A more specific error than the one below, to catch the
		// common mistake "file://foo".
		return "", errors.New("empty path")
	}
	// The URI's path is interpreted relative to dirFilepath, and in the local filesystem.
	// It must not try to escape its directory.
	uriFilepathRel, err := filepath.Localize(strings.TrimPrefix(uri.Path, "/"))
	if err != nil {
		return "", fmt.Errorf("%q cannot be localized: %w", uriFilepathRel, err)
	}

	// Check roots, if there are any.
	if len(rootFilepaths) > 0 {
		// To check against the roots, we need an absolute file path, not relative to the directory.
		// uriFilepath is local, so the joined path is under dirFilepath.
		uriFilepathAbs := filepath.Join(dirFilepath, uriFilepathRel)
		rootOK := false
		// Check that the requested file path is under some root.
		// Since both paths are absolute, that's equivalent to filepath.Rel constructing
		// a local path.
		for _, rootFilepathAbs := range rootFilepaths {
			if rel, err := filepath.Rel(rootFilepathAbs, uriFilepathAbs); err == nil && filepath.IsLocal(rel) {
				rootOK = true
				break
			}
		}
		if !rootOK {
			return "", fmt.Errorf("URI path %q is not under any root", uriFilepathAbs)
		}
	}
	return uriFilepathRel, nil
}

// fileRoots transforms the Roots obtained from the client into absolute paths on
// the local filesystem.
// TODO(jba): expose this functionality to user ResourceHandlers,
// so they don't have to repeat it.
func fileRoots(rawRoots []*Root) ([]string, error) {
	var fileRoots []string
	for _, r := range rawRoots {
		fr, err := fileRoot(r)
		if err != nil {
			return nil, err
		}
		fileRoots = append(fileRoots, fr)
	}
	return fileRoots, nil
}

// fileRoot returns the absolute path for Root.
func fileRoot(root *Root) (_ string, err error) {
	defer util.Wrapf(&err, "root %q", root.URI)

	// Convert to absolute file path.
	rurl, err := url.Parse(root.URI)
	if err != nil {
		return "", err
	}
	if rurl.Scheme != "file" {
		return "", errors.New("not a file URI")
	}
	if rurl.Path == "" {
		// A more specific error than the one below, to catch the
		// common mistake "file://foo".
		return "", errors.New("empty path")
	}
	// We don't want Localize here: we want an absolute path, which is not local.
	fileRoot := filepath.Clean(filepath.FromSlash(rurl.Path))
	if !filepath.IsAbs(fileRoot) {
		return "", errors.New("not an absolute path")
	}
	return fileRoot, nil
}

// Matches reports whether the receiver's uri template matches the uri.
// TODO: use "github.com/yosida95/uritemplate/v3"
func (sr *ServerResourceTemplate) Matches(uri string) bool {
	re, err := uriTemplateToRegexp(sr.ResourceTemplate.URITemplate)
	if err != nil {
		return false
	}
	return re.MatchString(uri)
}

func uriTemplateToRegexp(uriTemplate string) (*regexp.Regexp, error) {
	pat := uriTemplate
	var b strings.Builder
	b.WriteByte('^')
	seen := map[string]bool{}
	for len(pat) > 0 {
		literal, rest, ok := strings.Cut(pat, "{")
		b.WriteString(regexp.QuoteMeta(literal))
		if !ok {
			break
		}
		expr, rest, ok := strings.Cut(rest, "}")
		if !ok {
			return nil, errors.New("missing '}'")
		}
		pat = rest
		if strings.ContainsRune(expr, ',') {
			return nil, errors.New("can't handle commas in expressions")
		}
		if strings.ContainsRune(expr, ':') {
			return nil, errors.New("can't handle prefix modifiers in expressions")
		}
		if len(expr) > 0 && expr[len(expr)-1] == '*' {
			return nil, errors.New("can't handle explode modifiers in expressions")
		}

		// These sets of valid characters aren't accurate.
		// See https://datatracker.ietf.org/doc/html/rfc6570.
		var re, name string
		first := byte(0)
		if len(expr) > 0 {
			first = expr[0]
		}
		switch first {
		default:
			// {var} doesn't match slashes. (It should also fail to match other characters,
			// but this simplified implementation doesn't handle that.)
			re = `[^/]*`
			name = expr
		case '+':
			// {+var} matches anything, even slashes
			re = `.*`
			name = expr[1:]
		case '#', '.', '/', ';', '?', '&':
			return nil, fmt.Errorf("prefix character %c unsupported", first)
		}
		if seen[name] {
			return nil, fmt.Errorf("can't handle duplicate name %q", name)
		}
		seen[name] = true
		b.WriteString(re)
	}
	b.WriteByte('$')
	return regexp.Compile(b.String())
}


================================================
FILE: internal/mcp/resource_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"path/filepath"
	"runtime"
	"strings"
	"testing"
)

func TestFileRoot(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("TODO: fix for Windows")
	}

	for _, tt := range []struct {
		uri     string
		want    string
		wantErr string // error must contain this string
	}{
		{uri: "file:///foo", want: "/foo"},
		{uri: "file:///foo/bar", want: "/foo/bar"},
		{uri: "file:///foo/../bar", want: "/bar"},
		{uri: "file:/foo", want: "/foo"},
		{uri: "http:///foo", wantErr: "not a file"},
		{uri: "file://foo", wantErr: "empty path"},
		{uri: ":", wantErr: "missing protocol scheme"},
	} {
		got, err := fileRoot(&Root{URI: tt.uri})
		if err != nil {
			if tt.wantErr == "" {
				t.Errorf("%s: got %v, want success", tt.uri, err)
				continue
			}
			if !strings.Contains(err.Error(), tt.wantErr) {
				t.Errorf("%s: got %v, does not contain %q", tt.uri, err, tt.wantErr)
				continue
			}
		} else if tt.wantErr != "" {
			t.Errorf("%s: succeeded, but wanted error with %q", tt.uri, tt.wantErr)
		} else if got != tt.want {
			t.Errorf("%s: got %q, want %q", tt.uri, got, tt.want)
		}
	}
}

func TestComputeURIFilepath(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("TODO: fix for Windows")
	}
	// TODO(jba): test with Windows \\host paths and C: paths
	dirFilepath := filepath.FromSlash("/files")
	rootFilepaths := []string{
		filepath.FromSlash("/files/public"),
		filepath.FromSlash("/files/shared"),
	}
	for _, tt := range []struct {
		uri     string
		want    string
		wantErr string // error must contain this
	}{
		{"file:///public", "public", ""},
		{"file:///public/file", "public/file", ""},
		{"file:///shared/file", "shared/file", ""},
		{"http:///foo", "", "not a file"},
		{"file://foo", "", "empty"},
		{"file://foo/../bar", "", "localized"},
		{"file:///secret", "", "root"},
		{"file:///secret/file", "", "root"},
		{"file:///private/file", "", "root"},
	} {
		t.Run(tt.uri, func(t *testing.T) {
			tt.want = filepath.FromSlash(tt.want) // handle Windows
			got, gotErr := computeURIFilepath(tt.uri, dirFilepath, rootFilepaths)
			if gotErr != nil {
				if tt.wantErr == "" {
					t.Fatalf("got %v, wanted success", gotErr)
				}
				if !strings.Contains(gotErr.Error(), tt.wantErr) {
					t.Fatalf("got error %v, does not contain %q", gotErr, tt.wantErr)
				}
				return
			}
			if tt.wantErr != "" {
				t.Fatal("succeeded unexpectedly")
			}
			if got != tt.want {
				t.Errorf("got %q, want %q", got, tt.want)
			}
		})
	}
}

func TestReadFileResource(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("TODO: fix for Windows")
	}
	abs, err := filepath.Abs("testdata")
	if err != nil {
		t.Fatal(err)
	}
	dirFilepath := filepath.Join(abs, "files")
	got, err := readFileResource("file:///info.txt", dirFilepath, nil)
	if err != nil {
		t.Fatal(err)
	}
	want := "Contents\n"
	if g := string(got); g != want {
		t.Errorf("got %q, want %q", g, want)
	}
}

func TestTemplateMatch(t *testing.T) {
	uri := "file:///path/to/file"
	for _, tt := range []struct {
		template string
		want     bool
	}{
		{"file:///{}/{a}/{b}", true},
		{"file:///{a}/{b}", false},
		{"file:///{+path}", true},
		{"file:///{a}/{+path}", true},
	} {
		re, err := uriTemplateToRegexp(tt.template)
		if err != nil {
			t.Fatalf("%s: %v", tt.template, err)
		}
		got := re.MatchString(uri)
		if got != tt.want {
			t.Errorf("%s: got %t, want %t", tt.template, got, tt.want)
		}
	}
}


================================================
FILE: internal/mcp/root.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp


================================================
FILE: internal/mcp/server.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"encoding/base64"
	"encoding/gob"
	"encoding/json"
	"fmt"
	"iter"
	"net/url"
	"path/filepath"
	"slices"
	"sync"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/mcp/internal/util"
)

const DefaultPageSize = 1000

// A Server is an instance of an MCP server.
//
// Servers expose server-side MCP features, which can serve one or more MCP
// sessions by using [Server.Start] or [Server.Run].
type Server struct {
	// fixed at creation
	name    string
	version string
	opts    ServerOptions

	mu                      sync.Mutex
	prompts                 *featureSet[*ServerPrompt]
	tools                   *featureSet[*ServerTool]
	resources               *featureSet[*ServerResource]
	resourceTemplates       *featureSet[*ServerResourceTemplate]
	sessions                []*ServerSession
	sendingMethodHandler_   MethodHandler[*ServerSession]
	receivingMethodHandler_ MethodHandler[*ServerSession]
}

// ServerOptions is used to configure behavior of the server.
type ServerOptions struct {
	// Optional instructions for connected clients.
	Instructions string
	// If non-nil, called when "notifications/initialized" is received.
	InitializedHandler func(context.Context, *ServerSession, *InitializedParams)
	// PageSize is the maximum number of items to return in a single page for
	// list methods (e.g. ListTools).
	PageSize int
	// If non-nil, called when "notifications/roots/list_changed" is received.
	RootsListChangedHandler func(context.Context, *ServerSession, *RootsListChangedParams)
	// If non-nil, called when "notifications/progress" is received.
	ProgressNotificationHandler func(context.Context, *ServerSession, *ProgressNotificationParams)
}

// NewServer creates a new MCP server. The resulting server has no features:
// add features using [Server.AddTools], [Server.AddPrompts] and [Server.AddResources].
//
// The server can be connected to one or more MCP clients using [Server.Start]
// or [Server.Run].
//
// If non-nil, the provided options is used to configure the server.
func NewServer(name, version string, opts *ServerOptions) *Server {
	if opts == nil {
		opts = new(ServerOptions)
	}
	if opts.PageSize < 0 {
		panic(fmt.Errorf("invalid page size %d", opts.PageSize))
	}
	if opts.PageSize == 0 {
		opts.PageSize = DefaultPageSize
	}
	return &Server{
		name:                    name,
		version:                 version,
		opts:                    *opts,
		prompts:                 newFeatureSet(func(p *ServerPrompt) string { return p.Prompt.Name }),
		tools:                   newFeatureSet(func(t *ServerTool) string { return t.Tool.Name }),
		resources:               newFeatureSet(func(r *ServerResource) string { return r.Resource.URI }),
		resourceTemplates:       newFeatureSet(func(t *ServerResourceTemplate) string { return t.ResourceTemplate.URITemplate }),
		sendingMethodHandler_:   defaultSendingMethodHandler[*ServerSession],
		receivingMethodHandler_: defaultReceivingMethodHandler[*ServerSession],
	}
}

// AddPrompts adds the given prompts to the server,
// replacing any with the same names.
func (s *Server) AddPrompts(prompts ...*ServerPrompt) {
	// Only notify if something could change.
	if len(prompts) == 0 {
		return
	}
	// Assume there was a change, since add replaces existing roots.
	// (It's possible a root was replaced with an identical one, but not worth checking.)
	s.changeAndNotify(
		notificationPromptListChanged,
		&PromptListChangedParams{},
		func() bool { s.prompts.add(prompts...); return true })
}

// RemovePrompts removes the prompts with the given names.
// It is not an error to remove a nonexistent prompt.
func (s *Server) RemovePrompts(names ...string) {
	s.changeAndNotify(notificationPromptListChanged, &PromptListChangedParams{},
		func() bool { return s.prompts.remove(names...) })
}

// AddTools adds the given tools to the server,
// replacing any with the same names.
// The arguments must not be modified after this call.
//
// AddTools panics if errors are detected.
func (s *Server) AddTools(tools ...*ServerTool) {
	if err := s.addToolsErr(tools...); err != nil {
		panic(err)
	}
}

// addToolsErr is like [AddTools], but returns an error instead of panicking.
func (s *Server) addToolsErr(tools ...*ServerTool) error {
	// Only notify if something could change.
	if len(tools) == 0 {
		return nil
	}
	// Wrap the user's Handlers with rawHandlers that take a json.RawMessage.
	for _, st := range tools {
		if st.rawHandler == nil {
			// This ServerTool was not created with NewServerTool.
			if st.Handler == nil {
				return fmt.Errorf("AddTools: tool %q has no handler", st.Tool.Name)
			}
			st.rawHandler = newRawHandler(st)
			// Resolve the schemas, with no base URI. We don't expect tool schemas to
			// refer outside of themselves.
			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
			// if st.Tool.InputSchema != nil {
			// 	r, err := st.Tool.InputSchema.Resolve(&jsonschema.ResolveOptions{ValidateDefaults: true})
			// 	if err != nil {
			// 		return err
			// 	}
			// 	st.inputResolved = r
			// }

			// TODO: uncomment when output schemas drop.
			// if st.Tool.OutputSchema != nil {
			// 	st.outputResolved, err := st.Tool.OutputSchema.Resolve(&jsonschema.ResolveOptions{ValidateDefaults: true})
			// 	if err != nil {
			// 		return err
			// 	}
			// }
		}
	}

	// Assume there was a change, since add replaces existing tools.
	// (It's possible a tool was replaced with an identical one, but not worth checking.)
	// TODO: surface notify error here?
	s.changeAndNotify(notificationToolListChanged, &ToolListChangedParams{},
		func() bool { s.tools.add(tools...); return true })
	return nil
}

// RemoveTools removes the tools with the given names.
// It is not an error to remove a nonexistent tool.
func (s *Server) RemoveTools(names ...string) {
	s.changeAndNotify(notificationToolListChanged, &ToolListChangedParams{},
		func() bool { return s.tools.remove(names...) })
}

// AddResources adds the given resources to the server.
// If a resource with the same URI already exists, it is replaced.
// AddResources panics if a resource URI is invalid or not absolute (has an empty scheme).
func (s *Server) AddResources(resources ...*ServerResource) {
	// Only notify if something could change.
	if len(resources) == 0 {
		return
	}
	s.changeAndNotify(notificationResourceListChanged, &ResourceListChangedParams{},
		func() bool {
			for _, r := range resources {
				u, err := url.Parse(r.Resource.URI)
				if err != nil {
					panic(err) // url.Parse includes the URI in the error
				}
				if !u.IsAbs() {
					panic(fmt.Errorf("URI %s needs a scheme", r.Resource.URI))
				}
				s.resources.add(r)
			}
			return true
		})
}

// RemoveResources removes the resources with the given URIs.
// It is not an error to remove a nonexistent resource.
func (s *Server) RemoveResources(uris ...string) {
	s.changeAndNotify(notificationResourceListChanged, &ResourceListChangedParams{},
		func() bool { return s.resources.remove(uris...) })
}

// AddResourceTemplates adds the given resource templates to the server.
// If a resource template with the same URI template already exists, it will be replaced.
// AddResourceTemplates panics if a URI template is invalid or not absolute (has an empty scheme).
func (s *Server) AddResourceTemplates(templates ...*ServerResourceTemplate) {
	// Only notify if something could change.
	if len(templates) == 0 {
		return
	}
	s.changeAndNotify(notificationResourceListChanged, &ResourceListChangedParams{},
		func() bool {
			for _, t := range templates {
				// TODO: check template validity.
				s.resourceTemplates.add(t)
			}
			return true
		})
}

// RemoveResourceTemplates removes the resource templates with the given URI templates.
// It is not an error to remove a nonexistent resource.
func (s *Server) RemoveResourceTemplates(uriTemplates ...string) {
	s.changeAndNotify(notificationResourceListChanged, &ResourceListChangedParams{},
		func() bool { return s.resourceTemplates.remove(uriTemplates...) })
}

// changeAndNotify is called when a feature is added or removed.
// It calls change, which should do the work and report whether a change actually occurred.
// If there was a change, it notifies a snapshot of the sessions.
func (s *Server) changeAndNotify(notification string, params Params, change func() bool) {
	var sessions []*ServerSession
	// Lock for the change, but not for the notification.
	s.mu.Lock()
	if change() {
		sessions = slices.Clone(s.sessions)
	}
	s.mu.Unlock()
	notifySessions(sessions, notification, params)
}

// Sessions returns an iterator that yields the current set of server sessions.
func (s *Server) Sessions() iter.Seq[*ServerSession] {
	s.mu.Lock()
	clients := slices.Clone(s.sessions)
	s.mu.Unlock()
	return slices.Values(clients)
}

func (s *Server) listPrompts(_ context.Context, _ *ServerSession, params *ListPromptsParams) (*ListPromptsResult, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if params == nil {
		params = &ListPromptsParams{}
	}
	return paginateList(s.prompts, s.opts.PageSize, params, &ListPromptsResult{}, func(res *ListPromptsResult, prompts []*ServerPrompt) {
		res.Prompts = []*Prompt{} // avoid JSON null
		for _, p := range prompts {
			res.Prompts = append(res.Prompts, p.Prompt)
		}
	})
}

func (s *Server) getPrompt(ctx context.Context, cc *ServerSession, params *GetPromptParams) (*GetPromptResult, error) {
	s.mu.Lock()
	prompt, ok := s.prompts.get(params.Name)
	s.mu.Unlock()
	if !ok {
		// TODO: surface the error code over the wire, instead of flattening it into the string.
		return nil, fmt.Errorf("%s: unknown prompt %q", jsonrpc2.ErrInvalidParams, params.Name)
	}
	return prompt.Handler(ctx, cc, params)
}

func (s *Server) listTools(_ context.Context, _ *ServerSession, params *ListToolsParams) (*ListToolsResult, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if params == nil {
		params = &ListToolsParams{}
	}
	return paginateList(s.tools, s.opts.PageSize, params, &ListToolsResult{}, func(res *ListToolsResult, tools []*ServerTool) {
		res.Tools = []*Tool{} // avoid JSON null
		for _, t := range tools {
			res.Tools = append(res.Tools, t.Tool)
		}
	})
}

func (s *Server) callTool(ctx context.Context, cc *ServerSession, params *CallToolParamsFor[json.RawMessage]) (*CallToolResult, error) {
	s.mu.Lock()
	tool, ok := s.tools.get(params.Name)
	s.mu.Unlock()
	if !ok {
		return nil, fmt.Errorf("%s: unknown tool %q", jsonrpc2.ErrInvalidParams, params.Name)
	}
	return tool.rawHandler(ctx, cc, params)
}

func (s *Server) listResources(_ context.Context, _ *ServerSession, params *ListResourcesParams) (*ListResourcesResult, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if params == nil {
		params = &ListResourcesParams{}
	}
	return paginateList(s.resources, s.opts.PageSize, params, &ListResourcesResult{}, func(res *ListResourcesResult, resources []*ServerResource) {
		res.Resources = []*Resource{} // avoid JSON null
		for _, r := range resources {
			res.Resources = append(res.Resources, r.Resource)
		}
	})
}

func (s *Server) listResourceTemplates(_ context.Context, _ *ServerSession, params *ListResourceTemplatesParams) (*ListResourceTemplatesResult, error) {
	s.mu.Lock()
	defer s.mu.Unlock()
	if params == nil {
		params = &ListResourceTemplatesParams{}
	}
	return paginateList(s.resourceTemplates, s.opts.PageSize, params, &ListResourceTemplatesResult{},
		func(res *ListResourceTemplatesResult, rts []*ServerResourceTemplate) {
			res.ResourceTemplates = []*ResourceTemplate{} // avoid JSON null
			for _, rt := range rts {
				res.ResourceTemplates = append(res.ResourceTemplates, rt.ResourceTemplate)
			}
		})
}

func (s *Server) readResource(ctx context.Context, ss *ServerSession, params *ReadResourceParams) (*ReadResourceResult, error) {
	uri := params.URI
	// Look up the resource URI in the lists of resources and resource templates.
	// This is a security check as well as an information lookup.
	handler, mimeType, ok := s.lookupResourceHandler(uri)
	if !ok {
		// Don't expose the server configuration to the client.
		// Treat an unregistered resource the same as a registered one that couldn't be found.
		return nil, ResourceNotFoundError(uri)
	}
	res, err := handler(ctx, ss, params)
	if err != nil {
		return nil, err
	}
	if res == nil || res.Contents == nil {
		return nil, fmt.Errorf("reading resource %s: read handler returned nil information", uri)
	}
	// As a convenience, populate some fields.
	for _, c := range res.Contents {
		if c.URI == "" {
			c.URI = uri
		}
		if c.MIMEType == "" {
			c.MIMEType = mimeType
		}
	}
	return res, nil
}

// lookupResourceHandler returns the resource handler and MIME type for the resource or
// resource template matching uri. If none, the last return value is false.
func (s *Server) lookupResourceHandler(uri string) (ResourceHandler, string, bool) {
	s.mu.Lock()
	defer s.mu.Unlock()
	// Try resources first.
	if r, ok := s.resources.get(uri); ok {
		return r.Handler, r.Resource.MIMEType, true
	}
	// Look for matching template.
	for rt := range s.resourceTemplates.all() {
		if rt.Matches(uri) {
			return rt.Handler, rt.ResourceTemplate.MIMEType, true
		}
	}
	return nil, "", false
}

// fileResourceHandler returns a ReadResourceHandler that reads paths using dir as
// a base directory.
// It honors client roots and protects against path traversal attacks.
//
// The dir argument should be a filesystem path. It need not be absolute, but
// that is recommended to avoid a dependency on the current working directory (the
// check against client roots is done with an absolute path). If dir is not absolute
// and the current working directory is unavailable, FileResourceHandler panics.
//
// Lexical path traversal attacks, where the path has ".." elements that escape dir,
// are always caught. Go 1.24 and above also protects against symlink-based attacks,
// where symlinks under dir lead out of the tree.
func (s *Server) fileResourceHandler(dir string) ResourceHandler {
	return fileResourceHandler(dir)
}

func fileResourceHandler(dir string) ResourceHandler {
	// Convert dir to an absolute path.
	dirFilepath, err := filepath.Abs(dir)
	if err != nil {
		panic(err)
	}
	return func(ctx context.Context, ss *ServerSession, params *ReadResourceParams) (_ *ReadResourceResult, err error) {
		defer util.Wrapf(&err, "reading resource %s", params.URI)

		// TODO: use a memoizing API here.
		rootRes, err := ss.ListRoots(ctx, nil)
		if err != nil {
			return nil, fmt.Errorf("listing roots: %w", err)
		}
		roots, err := fileRoots(rootRes.Roots)
		if err != nil {
			return nil, err
		}
		data, err := readFileResource(params.URI, dirFilepath, roots)
		if err != nil {
			return nil, err
		}
		// TODO(jba): figure out mime type. Omit for now: Server.readResource will fill it in.
		return &ReadResourceResult{Contents: []*ResourceContents{NewBlobResourceContents(params.URI, "", data)}}, nil
	}
}

// Run runs the server over the given transport, which must be persistent.
//
// Run blocks until the client terminates the connection.
func (s *Server) Run(ctx context.Context, t Transport) error {
	ss, err := s.Connect(ctx, t)
	if err != nil {
		return err
	}
	return ss.Wait()
}

// bind implements the binder[*ServerSession] interface, so that Servers can
// be connected using [connect].
func (s *Server) bind(conn *jsonrpc2.Connection) *ServerSession {
	ss := &ServerSession{conn: conn, server: s}
	s.mu.Lock()
	s.sessions = append(s.sessions, ss)
	s.mu.Unlock()
	return ss
}

// disconnect implements the binder[*ServerSession] interface, so that
// Servers can be connected using [connect].
func (s *Server) disconnect(cc *ServerSession) {
	s.mu.Lock()
	defer s.mu.Unlock()
	s.sessions = slices.DeleteFunc(s.sessions, func(cc2 *ServerSession) bool {
		return cc2 == cc
	})
}

// Connect connects the MCP server over the given transport and starts handling
// messages.
//
// It returns a connection object that may be used to terminate the connection
// (with [Connection.Close]), or await client termination (with
// [Connection.Wait]).
func (s *Server) Connect(ctx context.Context, t Transport) (*ServerSession, error) {
	return connect(ctx, t, s)
}

func (s *Server) callInitializedHandler(ctx context.Context, ss *ServerSession, params *InitializedParams) (Result, error) {
	return callNotificationHandler(ctx, s.opts.InitializedHandler, ss, params)
}

func (s *Server) callRootsListChangedHandler(ctx context.Context, ss *ServerSession, params *RootsListChangedParams) (Result, error) {
	return callNotificationHandler(ctx, s.opts.RootsListChangedHandler, ss, params)
}

func (ss *ServerSession) callProgressNotificationHandler(ctx context.Context, params *ProgressNotificationParams) (Result, error) {
	return callNotificationHandler(ctx, ss.server.opts.ProgressNotificationHandler, ss, params)
}

// NotifyProgress sends a progress notification from the server to the client
// associated with this session.
// This is typically used to report on the status of a long-running request
// that was initiated by the client.
func (ss *ServerSession) NotifyProgress(ctx context.Context, params *ProgressNotificationParams) error {
	return handleNotify(ctx, ss, notificationProgress, params)
}

// A ServerSession is a logical connection from a single MCP client. Its
// methods can be used to send requests or notifications to the client. Create
// a session by calling [Server.Connect].
//
// Call [ServerSession.Close] to close the connection, or await client
// termination with [ServerSession.Wait].
type ServerSession struct {
	server           *Server
	conn             *jsonrpc2.Connection
	mu               sync.Mutex
	logLevel         LoggingLevel
	initializeParams *InitializeParams
	initialized      bool
}

// Ping pings the client.
func (ss *ServerSession) Ping(ctx context.Context, params *PingParams) error {
	_, err := handleSend[*emptyResult](ctx, ss, methodPing, params)
	return err
}

// ListRoots lists the client roots.
func (ss *ServerSession) ListRoots(ctx context.Context, params *ListRootsParams) (*ListRootsResult, error) {
	return handleSend[*ListRootsResult](ctx, ss, methodListRoots, orZero[Params](params))
}

// CreateMessage sends a sampling request to the client.
func (ss *ServerSession) CreateMessage(ctx context.Context, params *CreateMessageParams) (*CreateMessageResult, error) {
	return handleSend[*CreateMessageResult](ctx, ss, methodCreateMessage, orZero[Params](params))
}

// LoggingMessage sends a logging message to the client.
// The message is not sent if the client has not called SetLevel, or if its level
// is below that of the last SetLevel.
//
// TODO(jba): rename to Log or LogMessage. A logging message is the thing that is sent to logging.
func (ss *ServerSession) LoggingMessage(ctx context.Context, params *LoggingMessageParams) error {
	ss.mu.Lock()
	logLevel := ss.logLevel
	ss.mu.Unlock()
	if logLevel == "" {
		// The spec is unclear, but seems to imply that no log messages are sent until the client
		// sets the level.
		// TODO(jba): read other SDKs, possibly file an issue.
		return nil
	}
	if compareLevels(params.Level, logLevel) < 0 {
		return nil
	}
	return handleNotify(ctx, ss, notificationLoggingMessage, params)
}

// AddSendingMiddleware wraps the current sending method handler using the provided
// middleware. Middleware is applied from right to left, so that the first one is
// executed first.
//
// For example, AddSendingMiddleware(m1, m2, m3) augments the method handler as
// m1(m2(m3(handler))).
//
// Sending middleware is called when a request is sent. It is useful for tasks
// such as tracing, metrics, and adding progress tokens.
func (s *Server) AddSendingMiddleware(middleware ...Middleware[*ServerSession]) {
	s.mu.Lock()
	defer s.mu.Unlock()
	addMiddleware(&s.sendingMethodHandler_, middleware)
}

// AddReceivingMiddleware wraps the current receiving method handler using
// the provided middleware. Middleware is applied from right to left, so that the
// first one is executed first.
//
// For example, AddReceivingMiddleware(m1, m2, m3) augments the method handler as
// m1(m2(m3(handler))).
//
// Receiving middleware is called when a request is received. It is useful for tasks
// such as authentication, request logging and metrics.
func (s *Server) AddReceivingMiddleware(middleware ...Middleware[*ServerSession]) {
	s.mu.Lock()
	defer s.mu.Unlock()
	addMiddleware(&s.receivingMethodHandler_, middleware)
}

// serverMethodInfos maps from the RPC method name to serverMethodInfos.
var serverMethodInfos = map[string]methodInfo{
	methodInitialize:             newMethodInfo(sessionMethod((*ServerSession).initialize)),
	methodPing:                   newMethodInfo(sessionMethod((*ServerSession).ping)),
	methodListPrompts:            newMethodInfo(serverMethod((*Server).listPrompts)),
	methodGetPrompt:              newMethodInfo(serverMethod((*Server).getPrompt)),
	methodListTools:              newMethodInfo(serverMethod((*Server).listTools)),
	methodCallTool:               newMethodInfo(serverMethod((*Server).callTool)),
	methodListResources:          newMethodInfo(serverMethod((*Server).listResources)),
	methodListResourceTemplates:  newMethodInfo(serverMethod((*Server).listResourceTemplates)),
	methodReadResource:           newMethodInfo(serverMethod((*Server).readResource)),
	methodSetLevel:               newMethodInfo(sessionMethod((*ServerSession).setLevel)),
	notificationInitialized:      newMethodInfo(serverMethod((*Server).callInitializedHandler)),
	notificationRootsListChanged: newMethodInfo(serverMethod((*Server).callRootsListChangedHandler)),
	notificationProgress:         newMethodInfo(sessionMethod((*ServerSession).callProgressNotificationHandler)),
}

func (ss *ServerSession) sendingMethodInfos() map[string]methodInfo { return clientMethodInfos }

func (ss *ServerSession) receivingMethodInfos() map[string]methodInfo { return serverMethodInfos }

func (ss *ServerSession) sendingMethodHandler() methodHandler {
	ss.server.mu.Lock()
	defer ss.server.mu.Unlock()
	return ss.server.sendingMethodHandler_
}

func (ss *ServerSession) receivingMethodHandler() methodHandler {
	ss.server.mu.Lock()
	defer ss.server.mu.Unlock()
	return ss.server.receivingMethodHandler_
}

// getConn implements [session.getConn].
func (ss *ServerSession) getConn() *jsonrpc2.Connection { return ss.conn }

// handle invokes the method described by the given JSON RPC request.
func (ss *ServerSession) handle(ctx context.Context, req *JSONRPCRequest) (any, error) {
	ss.mu.Lock()
	initialized := ss.initialized
	ss.mu.Unlock()
	// From the spec:
	// "The client SHOULD NOT send requests other than pings before the server
	// has responded to the initialize request."
	switch req.Method {
	case "initialize", "ping":
	default:
		if !initialized {
			return nil, fmt.Errorf("method %q is invalid during session initialization", req.Method)
		}
	}
	// For the streamable transport, we need the request ID to correlate
	// server->client calls and notifications to the incoming request from which
	// they originated. See [idContext] for details.
	ctx = context.WithValue(ctx, idContextKey{}, req.ID)
	return handleReceive(ctx, ss, req)
}

func (ss *ServerSession) initialize(ctx context.Context, params *InitializeParams) (*InitializeResult, error) {
	ss.mu.Lock()
	ss.initializeParams = params
	ss.mu.Unlock()

	// Mark the connection as initialized when this method exits.
	// TODO: Technically, the server should not be considered initialized until it has
	// *responded*, but we don't have adequate visibility into the jsonrpc2
	// connection to implement that easily. In any case, once we've initialized
	// here, we can handle requests.
	defer func() {
		ss.mu.Lock()
		ss.initialized = true
		ss.mu.Unlock()
	}()

	version := "2025-03-26" // preferred version
	switch v := params.ProtocolVersion; v {
	case "2024-11-05", "2025-03-26":
		version = v
	}

	return &InitializeResult{
		// TODO(rfindley): alter behavior when falling back to an older version:
		// reject unsupported features.
		ProtocolVersion: version,
		Capabilities: &serverCapabilities{
			Prompts: &promptCapabilities{
				ListChanged: true,
			},
			Tools: &toolCapabilities{
				ListChanged: true,
			},
			Resources: &resourceCapabilities{
				ListChanged: true,
			},
			Logging: &loggingCapabilities{},
		},
		Instructions: ss.server.opts.Instructions,
		ServerInfo: &implementation{
			Name:    ss.server.name,
			Version: ss.server.version,
		},
	}, nil
}

func (ss *ServerSession) ping(context.Context, *PingParams) (*emptyResult, error) {
	return &emptyResult{}, nil
}

func (ss *ServerSession) setLevel(_ context.Context, params *SetLevelParams) (*emptyResult, error) {
	ss.mu.Lock()
	defer ss.mu.Unlock()
	ss.logLevel = params.Level
	return &emptyResult{}, nil
}

// Close performs a graceful shutdown of the connection, preventing new
// requests from being handled, and waiting for ongoing requests to return.
// Close then terminates the connection.
func (ss *ServerSession) Close() error {
	return ss.conn.Close()
}

// Wait waits for the connection to be closed by the client.
func (ss *ServerSession) Wait() error {
	return ss.conn.Wait()
}

// pageToken is the internal structure for the opaque pagination cursor.
// It will be Gob-encoded and then Base64-encoded for use as a string token.
type pageToken struct {
	LastUID string // The unique ID of the last resource seen.
}

// encodeCursor encodes a unique identifier (UID) into a opaque pagination cursor
// by serializing a pageToken struct.
func encodeCursor(uid string) (string, error) {
	var buf bytes.Buffer
	token := pageToken{LastUID: uid}
	encoder := gob.NewEncoder(&buf)
	if err := encoder.Encode(token); err != nil {
		return "", fmt.Errorf("failed to encode page token: %w", err)
	}
	return base64.URLEncoding.EncodeToString(buf.Bytes()), nil
}

// decodeCursor decodes an opaque pagination cursor into the original pageToken struct.
func decodeCursor(cursor string) (*pageToken, error) {
	decodedBytes, err := base64.URLEncoding.DecodeString(cursor)
	if err != nil {
		return nil, fmt.Errorf("failed to decode cursor: %w", err)
	}

	var token pageToken
	buf := bytes.NewBuffer(decodedBytes)
	decoder := gob.NewDecoder(buf)
	if err := decoder.Decode(&token); err != nil {
		return nil, fmt.Errorf("failed to decode page token: %w, cursor: %v", err, cursor)
	}
	return &token, nil
}

// paginateList is a generic helper that returns a paginated slice of items
// from a featureSet. It populates the provided result res with the items
// and sets its next cursor for subsequent pages.
// If there are no more pages, the next cursor within the result will be an empty string.
func paginateList[P listParams, R listResult[T], T any](fs *featureSet[T], pageSize int, params P, res R, setFunc func(R, []T)) (R, error) {
	var seq iter.Seq[T]
	if params.cursorPtr() == nil || *params.cursorPtr() == "" {
		seq = fs.all()
	} else {
		pageToken, err := decodeCursor(*params.cursorPtr())
		// According to the spec, invalid cursors should return Invalid params.
		if err != nil {
			var zero R
			return zero, jsonrpc2.ErrInvalidParams
		}
		seq = fs.above(pageToken.LastUID)
	}
	var count int
	var features []T
	for f := range seq {
		count++
		// If we've seen pageSize + 1 elements, we've gathered enough info to determine
		// if there's a next page. Stop processing the sequence.
		if count == pageSize+1 {
			break
		}
		features = append(features, f)
	}
	setFunc(res, features)
	// No remaining pages.
	if count < pageSize+1 {
		return res, nil
	}
	nextCursor, err := encodeCursor(fs.uniqueID(features[len(features)-1]))
	if err != nil {
		var zero R
		return zero, err
	}
	*res.nextCursorPtr() = nextCursor
	return res, nil
}


================================================
FILE: internal/mcp/server_example_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"fmt"
	"log"

	"golang.org/x/tools/internal/mcp"
)

type SayHiParams struct {
	Name string `json:"name"`
}

func SayHi(ctx context.Context, cc *mcp.ServerSession, params *mcp.CallToolParamsFor[SayHiParams]) (*mcp.CallToolResultFor[any], error) {
	return &mcp.CallToolResultFor[any]{
		Content: []*mcp.Content{
			mcp.NewTextContent("Hi " + params.Arguments.Name),
		},
	}, nil
}

func ExampleServer() {
	ctx := context.Background()
	clientTransport, serverTransport := mcp.NewInMemoryTransports()

	server := mcp.NewServer("greeter", "v0.0.1", nil)
	server.AddTools(mcp.NewServerTool("greet", "say hi", SayHi))

	serverSession, err := server.Connect(ctx, serverTransport)
	if err != nil {
		log.Fatal(err)
	}

	client := mcp.NewClient("client", "v0.0.1", nil)
	clientSession, err := client.Connect(ctx, clientTransport)
	if err != nil {
		log.Fatal(err)
	}

	res, err := clientSession.CallTool(ctx, &mcp.CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "user"},
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(res.Content[0].Text)

	clientSession.Close()
	serverSession.Wait()

	// Output: Hi user
}

// createSessions creates and connects an in-memory client and server session for testing purposes.
func createSessions(ctx context.Context) (*mcp.ClientSession, *mcp.ServerSession, *mcp.Server) {
	server := mcp.NewServer("server", "v0.0.1", nil)
	client := mcp.NewClient("client", "v0.0.1", nil)
	serverTransport, clientTransport := mcp.NewInMemoryTransports()
	serverSession, err := server.Connect(ctx, serverTransport)
	if err != nil {
		log.Fatal(err)
	}
	clientSession, err := client.Connect(ctx, clientTransport)
	if err != nil {
		log.Fatal(err)
	}
	return clientSession, serverSession, server
}


================================================
FILE: internal/mcp/server_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"log"
	"slices"
	"testing"

	"github.com/google/go-cmp/cmp"
)

type testItem struct {
	Name  string
	Value string
}

type testListParams struct {
	Cursor string
}

func (p *testListParams) cursorPtr() *string {
	return &p.Cursor
}

type testListResult struct {
	Items      []*testItem
	NextCursor string
}

func (r *testListResult) nextCursorPtr() *string {
	return &r.NextCursor
}

var allTestItems = []*testItem{
	{"alpha", "val-A"},
	{"bravo", "val-B"},
	{"charlie", "val-C"},
	{"delta", "val-D"},
	{"echo", "val-E"},
	{"foxtrot", "val-F"},
	{"golf", "val-G"},
	{"hotel", "val-H"},
	{"india", "val-I"},
	{"juliet", "val-J"},
	{"kilo", "val-K"},
}

// getCursor encodes a string input into a URL-safe base64 cursor,
// fatally logging any encoding errors.
func getCursor(input string) string {
	cursor, err := encodeCursor(input)
	if err != nil {
		log.Fatalf("encodeCursor(%s) error = %v", input, err)
	}
	return cursor
}

func TestServerPaginateBasic(t *testing.T) {
	testCases := []struct {
		name           string
		initialItems   []*testItem
		inputCursor    string
		inputPageSize  int
		wantFeatures   []*testItem
		wantNextCursor string
		wantErr        bool
	}{
		{
			name:           "FirstPage_DefaultSize_Full",
			initialItems:   allTestItems,
			inputCursor:    "",
			inputPageSize:  5,
			wantFeatures:   allTestItems[0:5],
			wantNextCursor: getCursor("echo"), // Based on last item of first page
			wantErr:        false,
		},
		{
			name:           "SecondPage_DefaultSize_Full",
			initialItems:   allTestItems,
			inputCursor:    getCursor("echo"),
			inputPageSize:  5,
			wantFeatures:   allTestItems[5:10],
			wantNextCursor: getCursor("juliet"), // Based on last item of second page
			wantErr:        false,
		},
		{
			name:           "SecondPage_DefaultSize_Full_OutOfOrder",
			initialItems:   append(allTestItems[5:], allTestItems[0:5]...),
			inputCursor:    getCursor("echo"),
			inputPageSize:  5,
			wantFeatures:   allTestItems[5:10],
			wantNextCursor: getCursor("juliet"), // Based on last item of second page
			wantErr:        false,
		},
		{
			name:           "SecondPage_DefaultSize_Full_Duplicates",
			initialItems:   append(allTestItems, allTestItems[0:5]...),
			inputCursor:    getCursor("echo"),
			inputPageSize:  5,
			wantFeatures:   allTestItems[5:10],
			wantNextCursor: getCursor("juliet"), // Based on last item of second page
			wantErr:        false,
		},
		{
			name:           "LastPage_Remaining",
			initialItems:   allTestItems,
			inputCursor:    getCursor("juliet"),
			inputPageSize:  5,
			wantFeatures:   allTestItems[10:11], // Only 1 item left
			wantNextCursor: "",                  // No more pages
			wantErr:        false,
		},
		{
			name:           "PageSize_1",
			initialItems:   allTestItems,
			inputCursor:    "",
			inputPageSize:  1,
			wantFeatures:   allTestItems[0:1],
			wantNextCursor: getCursor("alpha"),
			wantErr:        false,
		},
		{
			name:           "PageSize_All",
			initialItems:   allTestItems,
			inputCursor:    "",
			inputPageSize:  len(allTestItems), // Page size equals total
			wantFeatures:   allTestItems,
			wantNextCursor: "", // No more pages
			wantErr:        false,
		},
		{
			name:           "PageSize_LargerThanAll",
			initialItems:   allTestItems,
			inputCursor:    "",
			inputPageSize:  len(allTestItems) + 5, // Page size larger than total
			wantFeatures:   allTestItems,
			wantNextCursor: "",
			wantErr:        false,
		},
		{
			name:           "EmptySet",
			initialItems:   nil,
			inputCursor:    "",
			inputPageSize:  5,
			wantFeatures:   nil,
			wantNextCursor: "",
			wantErr:        false,
		},
		{
			name:           "InvalidCursor",
			initialItems:   allTestItems,
			inputCursor:    "not-a-valid-gob-base64-cursor",
			inputPageSize:  5,
			wantFeatures:   nil, // Should be nil for error cases
			wantNextCursor: "",
			wantErr:        true,
		},
		{
			name:           "AboveNonExistentID",
			initialItems:   allTestItems,
			inputCursor:    getCursor("dne"), // A UID that doesn't exist
			inputPageSize:  5,
			wantFeatures:   allTestItems[4:9], // Should return elements above UID.
			wantNextCursor: getCursor("india"),
			wantErr:        false,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			fs := newFeatureSet(func(t *testItem) string { return t.Name })
			fs.add(tc.initialItems...)
			params := &testListParams{Cursor: tc.inputCursor}
			gotResult, err := paginateList(fs, tc.inputPageSize, params, &testListResult{}, func(res *testListResult, items []*testItem) {
				res.Items = items
			})
			if (err != nil) != tc.wantErr {
				t.Errorf("paginateList(%s) error, got %v, wantErr %v", tc.name, err, tc.wantErr)
			}
			if tc.wantErr {
				return
			}
			if diff := cmp.Diff(tc.wantFeatures, gotResult.Items); diff != "" {
				t.Errorf("paginateList(%s) mismatch (-want +got):\n%s", tc.name, diff)
			}
			if tc.wantNextCursor != gotResult.NextCursor {
				t.Errorf("paginateList(%s) nextCursor, got %v, want %v", tc.name, gotResult.NextCursor, tc.wantNextCursor)
			}
		})
	}
}

func TestServerPaginateVariousPageSizes(t *testing.T) {
	fs := newFeatureSet(func(t *testItem) string { return t.Name })
	fs.add(allTestItems...)
	// Try all possible page sizes, ensuring we get the correct list of items.
	for pageSize := 1; pageSize < len(allTestItems)+1; pageSize++ {
		var gotItems []*testItem
		var nextCursor string
		wantChunks := slices.Collect(slices.Chunk(allTestItems, pageSize))
		index := 0
		// Iterate through all pages, comparing sub-slices to the paginated list.
		for {
			params := &testListParams{Cursor: nextCursor}
			gotResult, err := paginateList(fs, pageSize, params, &testListResult{}, func(res *testListResult, items []*testItem) {
				res.Items = items
			})
			if err != nil {
				t.Fatalf("paginateList() unexpected error for pageSize %d, cursor %q: %v", pageSize, nextCursor, err)
			}
			if diff := cmp.Diff(wantChunks[index], gotResult.Items); diff != "" {
				t.Errorf("paginateList mismatch (-want +got):\n%s", diff)
			}
			gotItems = append(gotItems, gotResult.Items...)
			nextCursor = gotResult.NextCursor
			if nextCursor == "" {
				break
			}
			index++
		}

		if len(gotItems) != len(allTestItems) {
			t.Fatalf("paginateList() returned %d items, want %d", len(allTestItems), len(gotItems))
		}
	}
}


================================================
FILE: internal/mcp/shared.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains code shared between client and server, including
// method handler and middleware definitions.
// TODO: much of this is here so that we can factor out commonalities using
// generics. Perhaps it can be simplified with reflection.

package mcp

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"reflect"
	"slices"
	"strings"
	"time"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

// A MethodHandler handles MCP messages.
// For methods, exactly one of the return values must be nil.
// For notifications, both must be nil.
type MethodHandler[S Session] func(ctx context.Context, _ S, method string, params Params) (result Result, err error)

// A methodHandler is a MethodHandler[Session] for some session.
// We need to give up type safety here, or we will end up with a type cycle somewhere
// else. For example, if Session.methodHandler returned a MethodHandler[Session],
// the compiler would complain.
type methodHandler any // MethodHandler[*ClientSession] | MethodHandler[*ServerSession]

// A Session is either a ClientSession or a ServerSession.
type Session interface {
	*ClientSession | *ServerSession
	sendingMethodInfos() map[string]methodInfo
	receivingMethodInfos() map[string]methodInfo
	sendingMethodHandler() methodHandler
	receivingMethodHandler() methodHandler
	getConn() *jsonrpc2.Connection
}

// Middleware is a function from MethodHandlers to MethodHandlers.
type Middleware[S Session] func(MethodHandler[S]) MethodHandler[S]

// addMiddleware wraps the handler in the middleware functions.
func addMiddleware[S Session](handlerp *MethodHandler[S], middleware []Middleware[S]) {
	for _, m := range slices.Backward(middleware) {
		*handlerp = m(*handlerp)
	}
}

func defaultSendingMethodHandler[S Session](ctx context.Context, session S, method string, params Params) (Result, error) {
	info, ok := session.sendingMethodInfos()[method]
	if !ok {
		// This can be called from user code, with an arbitrary value for method.
		return nil, jsonrpc2.ErrNotHandled
	}
	// Notifications don't have results.
	if strings.HasPrefix(method, "notifications/") {
		return nil, session.getConn().Notify(ctx, method, params)
	}
	// Create the result to unmarshal into.
	// The concrete type of the result is the return type of the receiving function.
	res := info.newResult()
	if err := call(ctx, session.getConn(), method, params, res); err != nil {
		return nil, err
	}
	return res, nil
}

// Helper methods to avoid typed nil.
func orZero[T any, P *U, U any](p P) T {
	if p == nil {
		var zero T
		return zero
	}
	return any(p).(T)
}

func handleNotify[S Session](ctx context.Context, session S, method string, params Params) error {
	mh := session.sendingMethodHandler().(MethodHandler[S])
	_, err := mh(ctx, session, method, params)
	return err
}

func handleSend[R Result, S Session](ctx context.Context, s S, method string, params Params) (R, error) {
	mh := s.sendingMethodHandler().(MethodHandler[S])
	// mh might be user code, so ensure that it returns the right values for the jsonrpc2 protocol.
	res, err := mh(ctx, s, method, params)
	if err != nil {
		var z R
		return z, err
	}
	return res.(R), nil
}

// defaultReceivingMethodHandler is the initial MethodHandler for servers and clients, before being wrapped by middleware.
func defaultReceivingMethodHandler[S Session](ctx context.Context, session S, method string, params Params) (Result, error) {
	info, ok := session.receivingMethodInfos()[method]
	if !ok {
		// This can be called from user code, with an arbitrary value for method.
		return nil, jsonrpc2.ErrNotHandled
	}
	return info.handleMethod.(MethodHandler[S])(ctx, session, method, params)
}

func handleReceive[S Session](ctx context.Context, session S, req *JSONRPCRequest) (Result, error) {
	info, ok := session.receivingMethodInfos()[req.Method]
	if !ok {
		return nil, jsonrpc2.ErrNotHandled
	}
	params, err := info.unmarshalParams(req.Params)
	if err != nil {
		return nil, fmt.Errorf("handleRequest %q: %w", req.Method, err)
	}

	mh := session.receivingMethodHandler().(MethodHandler[S])
	// mh might be user code, so ensure that it returns the right values for the jsonrpc2 protocol.
	res, err := mh(ctx, session, req.Method, params)
	if err != nil {
		return nil, err
	}
	return res, nil
}

// methodInfo is information about sending and receiving a method.
type methodInfo struct {
	// Unmarshal params from the wire into a Params struct.
	// Used on the receive side.
	unmarshalParams func(json.RawMessage) (Params, error)
	// Run the code when a call to the method is received.
	// Used on the receive side.
	handleMethod methodHandler
	// Create a pointer to a Result struct.
	// Used on the send side.
	newResult func() Result
}

// The following definitions support converting from typed to untyped method handlers.
// Type parameter meanings:
// - S: sessions
// - P: params
// - R: results

// A typedMethodHandler is like a MethodHandler, but with type information.
type typedMethodHandler[S Session, P Params, R Result] func(context.Context, S, P) (R, error)

type paramsPtr[T any] interface {
	*T
	Params
}

// newMethodInfo creates a methodInfo from a typedMethodHandler.
func newMethodInfo[S Session, P paramsPtr[T], R Result, T any](d typedMethodHandler[S, P, R]) methodInfo {
	return methodInfo{
		unmarshalParams: func(m json.RawMessage) (Params, error) {
			var p P
			if m != nil {
				if err := json.Unmarshal(m, &p); err != nil {
					return nil, fmt.Errorf("unmarshaling %q into a %T: %w", m, p, err)
				}
			}
			return orZero[Params](p), nil
		},
		handleMethod: MethodHandler[S](func(ctx context.Context, session S, _ string, params Params) (Result, error) {
			if params == nil {
				return d(ctx, session, nil)
			}
			return d(ctx, session, params.(P))
		}),
		// newResult is used on the send side, to construct the value to unmarshal the result into.
		// R is a pointer to a result struct. There is no way to "unpointer" it without reflection.
		// TODO(jba): explore generic approaches to this, perhaps by treating R in
		// the signature as the unpointered type.
		newResult: func() Result { return reflect.New(reflect.TypeFor[R]().Elem()).Interface().(R) },
	}
}

// serverMethod is glue for creating a typedMethodHandler from a method on Server.
func serverMethod[P Params, R Result](
	f func(*Server, context.Context, *ServerSession, P) (R, error),
) typedMethodHandler[*ServerSession, P, R] {
	return func(ctx context.Context, ss *ServerSession, p P) (R, error) {
		return f(ss.server, ctx, ss, p)
	}
}

// clientMethod is glue for creating a typedMethodHandler from a method on Server.
func clientMethod[P Params, R Result](
	f func(*Client, context.Context, *ClientSession, P) (R, error),
) typedMethodHandler[*ClientSession, P, R] {
	return func(ctx context.Context, cs *ClientSession, p P) (R, error) {
		return f(cs.client, ctx, cs, p)
	}
}

// sessionMethod is glue for creating a typedMethodHandler from a method on ServerSession.
func sessionMethod[S Session, P Params, R Result](f func(S, context.Context, P) (R, error)) typedMethodHandler[S, P, R] {
	return func(ctx context.Context, sess S, p P) (R, error) {
		return f(sess, ctx, p)
	}
}

// Error codes
const (
	// The error code to return when a resource isn't found.
	// See https://modelcontextprotocol.io/specification/2025-03-26/server/resources#error-handling
	// However, the code they chose is in the wrong space
	// (see https://github.com/modelcontextprotocol/modelcontextprotocol/issues/509).
	// so we pick a different one, arbitrarily for now (until they fix it).
	// The immediate problem is that jsonprc2 defines -32002 as "server closing".
	CodeResourceNotFound = -31002
	// The error code if the method exists and was called properly, but the peer does not support it.
	CodeUnsupportedMethod = -31001
)

func callNotificationHandler[S Session, P any](ctx context.Context, h func(context.Context, S, *P), sess S, params *P) (Result, error) {
	if h != nil {
		h(ctx, sess, params)
	}
	return nil, nil
}

// notifySessions calls Notify on all the sessions.
// Should be called on a copy of the peer sessions.
func notifySessions[S Session](sessions []S, method string, params Params) {
	if sessions == nil {
		return
	}
	// TODO: make this timeout configurable, or call Notify asynchronously.
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	for _, s := range sessions {
		if err := handleNotify(ctx, s, method, params); err != nil {
			// TODO(jba): surface this error better
			log.Printf("calling %s: %v", method, err)
		}
	}
}

type Meta struct {
	Data map[string]any `json:",omitempty"`
	// For params, the progress token can be nil, a string or an integer.
	// It should be nil for results.
	ProgressToken any `json:"progressToken,omitempty"`
}

type metaSansMethods Meta // avoid infinite recursion during marshaling

func (m Meta) MarshalJSON() ([]byte, error) {
	if p := m.ProgressToken; p != nil {
		if k := reflect.ValueOf(p).Kind(); k != reflect.Int && k != reflect.String {
			return nil, fmt.Errorf("bad type %T for Meta.ProgressToken: must be int or string", p)
		}
	}
	// If ProgressToken is nil, accept Data["progressToken"]. We can't call marshalStructWithMap
	// in that case because it will complain about duplicate fields. (We'd have to
	// make it much smarter to avoid that; not worth it.)
	if m.ProgressToken == nil && len(m.Data) > 0 {
		return json.Marshal(m.Data)
	}
	return marshalStructWithMap((*metaSansMethods)(&m), "Data")
}

func (m *Meta) UnmarshalJSON(data []byte) error {
	return unmarshalStructWithMap(data, (*metaSansMethods)(m), "Data")
}

// Params is a parameter (input) type for an MCP call or notification.
type Params interface {
	// Returns a pointer to the params's Meta field.
	GetMeta() *Meta
}

// Result is a result of an MCP call.
type Result interface {
	// Returns a pointer to the result's Meta field.
	GetMeta() *Meta
}

// emptyResult is returned by methods that have no result, like ping.
// Those methods cannot return nil, because jsonrpc2 cannot handle nils.
type emptyResult struct{}

func (*emptyResult) GetMeta() *Meta { panic("should never be called") }

type listParams interface {
	// Returns a pointer to the param's Cursor field.
	cursorPtr() *string
}

type listResult[T any] interface {
	// Returns a pointer to the param's NextCursor field.
	nextCursorPtr() *string
}


================================================
FILE: internal/mcp/shared_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"encoding/json"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
)

func TestMetaMarshal(t *testing.T) {
	// Verify that Meta values round-trip.
	for _, meta := range []Meta{
		{Data: nil, ProgressToken: nil},
		{Data: nil, ProgressToken: "p"},
		{Data: map[string]any{"d": true}, ProgressToken: nil},
		{Data: map[string]any{"d": true}, ProgressToken: "p"},
	} {
		got := roundTrip(t, meta)
		if !cmp.Equal(got, meta) {
			t.Errorf("\ngot  %#v\nwant %#v", got, meta)
		}
	}

	// Check errors.
	for _, tt := range []struct {
		meta Meta
		want string
	}{
		{
			Meta{Data: map[string]any{"progressToken": "p"}, ProgressToken: 1},
			"duplicate",
		},
		{
			Meta{ProgressToken: true},
			"bad type",
		},
	} {
		_, err := json.Marshal(tt.meta)
		if err == nil || !strings.Contains(err.Error(), tt.want) {
			t.Errorf("%+v: got %v, want error containing %q", tt.meta, err, tt.want)
		}
	}

	// Accept progressToken in map if the field is nil.
	// It will unmarshal by populating ProgressToken.
	meta := Meta{Data: map[string]any{"progressToken": "p"}}
	got := roundTrip(t, meta)
	want := Meta{ProgressToken: "p"}
	if !cmp.Equal(got, want) {
		t.Errorf("got %+v, want %+v", got, want)
	}
}

func roundTrip[T any](t *testing.T, v T) T {
	t.Helper()
	bytes, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	var res T
	if err := json.Unmarshal(bytes, &res); err != nil {
		t.Fatal(err)
	}
	return res
}

// TODO(jba): this shouldn't be in this file, but tool_test.go doesn't have access to unexported symbols.
func TestNewServerToolValidate(t *testing.T) {
	// Check that the tool returned from NewServerTool properly validates its input schema.

	type req struct {
		I int
		B bool
		S string `json:",omitempty"`
		P *int   `json:",omitempty"`
	}

	dummyHandler := func(context.Context, *ServerSession, *CallToolParamsFor[req]) (*CallToolResultFor[any], error) {
		return nil, nil
	}

	tool := NewServerTool("test", "test", dummyHandler)
	// Need to add the tool to a server to get resolved schemas.
	// s := NewServer("", "", nil)

	for _, tt := range []struct {
		desc string
		args map[string]any
		want string // error should contain this string; empty for success
	}{
		{
			"both required",
			map[string]any{"I": 1, "B": true},
			"",
		},
		{
			"optional",
			map[string]any{"I": 1, "B": true, "S": "foo"},
			"",
		},
		{
			"wrong type",
			map[string]any{"I": 1.5, "B": true},
			"cannot unmarshal",
		},
		{
			"extra property",
			map[string]any{"I": 1, "B": true, "C": 2},
			"unknown field",
		},
		{
			"value for pointer",
			map[string]any{"I": 1, "B": true, "P": 3},
			"",
		},
		{
			"null for pointer",
			map[string]any{"I": 1, "B": true, "P": nil},
			"",
		},
	} {
		t.Run(tt.desc, func(t *testing.T) {
			raw, err := json.Marshal(tt.args)
			if err != nil {
				t.Fatal(err)
			}
			_, err = tool.rawHandler(context.Background(), nil,
				&CallToolParamsFor[json.RawMessage]{Arguments: json.RawMessage(raw)})
			if err == nil && tt.want != "" {
				t.Error("got success, wanted failure")
			}
			if err != nil {
				if tt.want == "" {
					t.Fatalf("failed with:\n%s\nwanted success", err)
				}
				if !strings.Contains(err.Error(), tt.want) {
					t.Fatalf("got:\n%s\nwanted to contain %q", err, tt.want)
				}
			}
		})
	}
}


================================================
FILE: internal/mcp/sse.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bufio"
	"bytes"
	"context"
	"crypto/rand"
	"errors"
	"fmt"
	"io"
	"iter"
	"net/http"
	"net/url"
	"strings"
	"sync"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

// This file implements support for SSE (HTTP with server-sent events)
// transport server and client.
// https://modelcontextprotocol.io/specification/2024-11-05/basic/transports
//
// The transport is simple, at least relative to the new streamable transport
// introduced in the 2025-03-26 version of the spec. In short:
//
//  1. Sessions are initiated via a hanging GET request, which streams
//     server->client messages as SSE 'message' events.
//  2. The first event in the SSE stream must be an 'endpoint' event that
//     informs the client of the session endpoint.
//  3. The client POSTs client->server messages to the session endpoint.
//
// Therefore, the each new GET request hands off its responsewriter to an
// [SSEServerTransport] type that abstracts the transport as follows:
//  - Write writes a new event to the responseWriter, or fails if the GET has
//  exited.
//  - Read reads off a message queue that is pushed to via POST requests.
//  - Close causes the hanging GET to exit.

// An event is a server-sent event.
type event struct {
	name string
	id   string
	data []byte
}

func (e event) empty() bool {
	return e.name == "" && e.id == "" && len(e.data) == 0
}

// writeEvent writes the event to w, and flushes.
func writeEvent(w io.Writer, evt event) (int, error) {
	var b bytes.Buffer
	if evt.name != "" {
		fmt.Fprintf(&b, "event: %s\n", evt.name)
	}
	if evt.id != "" {
		fmt.Fprintf(&b, "id: %s\n", evt.id)
	}
	fmt.Fprintf(&b, "data: %s\n\n", string(evt.data))
	n, err := w.Write(b.Bytes())
	if f, ok := w.(http.Flusher); ok {
		f.Flush()
	}
	return n, err
}

// SSEHandler is an http.Handler that serves SSE-based MCP sessions as defined by
// the [2024-11-05 version] of the MCP spec.
//
// [2024-11-05 version]: https://modelcontextprotocol.io/specification/2024-11-05/basic/transports
type SSEHandler struct {
	getServer    func(request *http.Request) *Server
	onConnection func(*ServerSession) // for testing; must not block

	mu       sync.Mutex
	sessions map[string]*SSEServerTransport
}

// NewSSEHandler returns a new [SSEHandler] that creates and manages MCP
// sessions created via incoming HTTP requests.
//
// Sessions are created when the client issues a GET request to the server,
// which must accept text/event-stream responses (server-sent events).
// For each such request, a new [SSEServerTransport] is created with a distinct
// messages endpoint, and connected to the server returned by getServer. It is
// up to the user whether getServer returns a distinct [Server] for each new
// request, or reuses an existing server.
//
// The SSEHandler also handles requests to the message endpoints, by
// delegating them to the relevant server transport.
//
// TODO(rfindley): add options.
func NewSSEHandler(getServer func(request *http.Request) *Server) *SSEHandler {
	return &SSEHandler{
		getServer: getServer,
		sessions:  make(map[string]*SSEServerTransport),
	}
}

// A SSEServerTransport is a logical SSE session created through a hanging GET
// request.
//
// When connected, it returns the following [Connection] implementation:
//   - Writes are SSE 'message' events to the GET response.
//   - Reads are received from POSTs to the session endpoint, via
//     [SSEServerTransport.ServeHTTP].
//   - Close terminates the hanging GET.
type SSEServerTransport struct {
	endpoint string
	incoming chan JSONRPCMessage // queue of incoming messages; never closed

	// We must guard both pushes to the incoming queue and writes to the response
	// writer, because incoming POST requests are arbitrarily concurrent and we
	// need to ensure we don't write push to the queue, or write to the
	// ResponseWriter, after the session GET request exits.
	mu     sync.Mutex
	w      http.ResponseWriter // the hanging response body
	closed bool                // set when the stream is closed
	done   chan struct{}       // closed when the connection is closed
}

// NewSSEServerTransport creates a new SSE transport for the given messages
// endpoint, and hanging GET response.
//
// Use [SSEServerTransport.Connect] to initiate the flow of messages.
//
// The transport is itself an [http.Handler]. It is the caller's responsibility
// to ensure that the resulting transport serves HTTP requests on the given
// session endpoint.
//
// Most callers should instead use an [SSEHandler], which transparently handles
// the delegation to SSEServerTransports.
func NewSSEServerTransport(endpoint string, w http.ResponseWriter) *SSEServerTransport {
	return &SSEServerTransport{
		endpoint: endpoint,
		w:        w,
		incoming: make(chan JSONRPCMessage, 100),
		done:     make(chan struct{}),
	}
}

// ServeHTTP handles POST requests to the transport endpoint.
func (t *SSEServerTransport) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	// Read and parse the message.
	data, err := io.ReadAll(req.Body)
	if err != nil {
		http.Error(w, "failed to read body", http.StatusBadRequest)
		return
	}
	// Optionally, we could just push the data onto a channel, and let the
	// message fail to parse when it is read. This failure seems a bit more
	// useful
	msg, err := jsonrpc2.DecodeMessage(data)
	if err != nil {
		http.Error(w, "failed to parse body", http.StatusBadRequest)
		return
	}
	select {
	case t.incoming <- msg:
		w.WriteHeader(http.StatusAccepted)
	case <-t.done:
		http.Error(w, "session closed", http.StatusBadRequest)
	}
}

// Connect sends the 'endpoint' event to the client.
// See [SSEServerTransport] for more details on the [Connection] implementation.
func (t *SSEServerTransport) Connect(context.Context) (Connection, error) {
	t.mu.Lock()
	_, err := writeEvent(t.w, event{
		name: "endpoint",
		data: []byte(t.endpoint),
	})
	t.mu.Unlock()
	if err != nil {
		return nil, err
	}
	return sseServerConn{t}, nil
}

func (h *SSEHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	sessionID := req.URL.Query().Get("sessionid")

	// TODO: consider checking Content-Type here. For now, we are lax.

	// For POST requests, the message body is a message to send to a session.
	if req.Method == http.MethodPost {
		// Look up the session.
		if sessionID == "" {
			http.Error(w, "sessionid must be provided", http.StatusBadRequest)
			return
		}
		h.mu.Lock()
		session := h.sessions[sessionID]
		h.mu.Unlock()
		if session == nil {
			http.Error(w, "session not found", http.StatusNotFound)
			return
		}

		session.ServeHTTP(w, req)
		return
	}

	if req.Method != http.MethodGet {
		http.Error(w, "invalid method", http.StatusMethodNotAllowed)
		return
	}

	// GET requests create a new session, and serve messages over SSE.

	// TODO: it's not entirely documented whether we should check Accept here.
	// Let's again be lax and assume the client will accept SSE.

	w.Header().Set("Content-Type", "text/event-stream")
	w.Header().Set("Cache-Control", "no-cache")
	w.Header().Set("Connection", "keep-alive")

	sessionID = rand.Text()
	endpoint, err := req.URL.Parse("?sessionid=" + sessionID)
	if err != nil {
		http.Error(w, "internal error: failed to create endpoint", http.StatusInternalServerError)
		return
	}

	transport := NewSSEServerTransport(endpoint.RequestURI(), w)

	// The session is terminated when the request exits.
	h.mu.Lock()
	h.sessions[sessionID] = transport
	h.mu.Unlock()
	defer func() {
		h.mu.Lock()
		delete(h.sessions, sessionID)
		h.mu.Unlock()
	}()

	// TODO(hxjiang): getServer returns nil will panic.
	server := h.getServer(req)
	ss, err := server.Connect(req.Context(), transport)
	if err != nil {
		http.Error(w, "connection failed", http.StatusInternalServerError)
		return
	}
	if h.onConnection != nil {
		h.onConnection(ss)
	}
	defer ss.Close() // close the transport when the GET exits

	select {
	case <-req.Context().Done():
	case <-transport.done:
	}
}

// sseServerConn implements the [Connection] interface for a single [SSEServerTransport].
// It hides the Connection interface from the SSEServerTransport API.
type sseServerConn struct {
	t *SSEServerTransport
}

// Read implements jsonrpc2.Reader.
func (s sseServerConn) Read(ctx context.Context) (JSONRPCMessage, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case msg := <-s.t.incoming:
		return msg, nil
	case <-s.t.done:
		return nil, io.EOF
	}
}

// Write implements jsonrpc2.Writer.
func (s sseServerConn) Write(ctx context.Context, msg JSONRPCMessage) error {
	if ctx.Err() != nil {
		return ctx.Err()
	}

	data, err := jsonrpc2.EncodeMessage(msg)
	if err != nil {
		return err
	}

	s.t.mu.Lock()
	defer s.t.mu.Unlock()

	// Note that it is invalid to write to a ResponseWriter after ServeHTTP has
	// exited, and so we must lock around this write and check isDone, which is
	// set before the hanging GET exits.
	if s.t.closed {
		return io.EOF
	}

	_, err = writeEvent(s.t.w, event{name: "message", data: data})
	return err
}

// Close implements io.Closer, and closes the session.
//
// It must be safe to call Close more than once, as the close may
// asynchronously be initiated by either the server closing its connection, or
// by the hanging GET exiting.
func (s sseServerConn) Close() error {
	s.t.mu.Lock()
	defer s.t.mu.Unlock()
	if !s.t.closed {
		s.t.closed = true
		close(s.t.done)
	}
	return nil
}

// An SSEClientTransport is a [Transport] that can communicate with an MCP
// endpoint serving the SSE transport defined by the 2024-11-05 version of the
// spec.
//
// https://modelcontextprotocol.io/specification/2024-11-05/basic/transports
type SSEClientTransport struct {
	sseEndpoint *url.URL
	opts        SSEClientTransportOptions
}

// SSEClientTransportOptions provides options for the [NewSSEClientTransport]
// constructor.
type SSEClientTransportOptions struct {
	// HTTPClient is the client to use for making HTTP requests. If nil,
	// http.DefaultClient is used.
	HTTPClient *http.Client
}

// NewSSEClientTransport returns a new client transport that connects to the
// SSE server at the provided URL.
//
// NewSSEClientTransport panics if the given URL is invalid.
func NewSSEClientTransport(baseURL string, opts *SSEClientTransportOptions) *SSEClientTransport {
	url, err := url.Parse(baseURL)
	if err != nil {
		panic(fmt.Sprintf("invalid base url: %v", err))
	}
	t := &SSEClientTransport{
		sseEndpoint: url,
	}
	if opts != nil {
		t.opts = *opts
	}
	return t
}

// Connect connects through the client endpoint.
func (c *SSEClientTransport) Connect(ctx context.Context) (Connection, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", c.sseEndpoint.String(), nil)
	if err != nil {
		return nil, err
	}
	httpClient := c.opts.HTTPClient
	if httpClient == nil {
		httpClient = http.DefaultClient
	}
	req.Header.Set("Accept", "text/event-stream")
	resp, err := httpClient.Do(req)
	if err != nil {
		return nil, err
	}

	msgEndpoint, err := func() (*url.URL, error) {
		var evt event
		for evt, err = range scanEvents(resp.Body) {
			break
		}
		if err != nil {
			return nil, err
		}
		if evt.name != "endpoint" {
			return nil, fmt.Errorf("first event is %q, want %q", evt.name, "endpoint")
		}
		raw := string(evt.data)
		return c.sseEndpoint.Parse(raw)
	}()
	if err != nil {
		resp.Body.Close()
		return nil, fmt.Errorf("missing endpoint: %v", err)
	}

	// From here on, the stream takes ownership of resp.Body.
	s := &sseClientConn{
		sseEndpoint: c.sseEndpoint,
		msgEndpoint: msgEndpoint,
		incoming:    make(chan []byte, 100),
		body:        resp.Body,
		done:        make(chan struct{}),
	}

	go func() {
		defer s.Close() // close the transport when the GET exits

		for evt, err := range scanEvents(resp.Body) {
			if err != nil {
				return
			}
			select {
			case s.incoming <- evt.data:
			case <-s.done:
				return
			}
		}
	}()

	return s, nil
}

// scanEvents iterates SSE events in the given scanner. The iterated error is
// terminal: if encountered, the stream is corrupt or broken and should no
// longer be used.
//
// TODO(rfindley): consider a different API here that makes failure modes more
// apparent.
func scanEvents(r io.Reader) iter.Seq2[event, error] {
	scanner := bufio.NewScanner(r)
	const maxTokenSize = 1 * 1024 * 1024 // 1 MiB max line size
	scanner.Buffer(nil, maxTokenSize)

	// TODO: investigate proper behavior when events are out of order, or have
	// non-standard names.
	var (
		eventKey = []byte("event")
		idKey    = []byte("id")
		dataKey  = []byte("data")
	)

	return func(yield func(event, error) bool) {
		// iterate event from the wire.
		// https://developer.mozilla.org/en-US/docs/Web/API/Server-sent_events/Using_server-sent_events#examples
		//
		//  - `key: value` line records.
		//  - Consecutive `data: ...` fields are joined with newlines.
		//  - Unrecognized fields are ignored. Since we only care about 'event', 'id', and
		//   'data', these are the only three we consider.
		//  - Lines starting with ":" are ignored.
		//  - Records are terminated with two consecutive newlines.
		var (
			evt     event
			dataBuf *bytes.Buffer // if non-nil, preceding field was also data
		)
		flushData := func() {
			if dataBuf != nil {
				evt.data = dataBuf.Bytes()
				dataBuf = nil
			}
		}
		for scanner.Scan() {
			line := scanner.Bytes()
			if len(line) == 0 {
				flushData()
				// \n\n is the record delimiter
				if !evt.empty() && !yield(evt, nil) {
					return
				}
				evt = event{}
				continue
			}
			before, after, found := bytes.Cut(line, []byte{':'})
			if !found {
				yield(event{}, fmt.Errorf("malformed line in SSE stream: %q", string(line)))
				return
			}
			if !bytes.Equal(before, dataKey) {
				flushData()
			}
			switch {
			case bytes.Equal(before, eventKey):
				evt.name = strings.TrimSpace(string(after))
			case bytes.Equal(before, idKey):
				evt.id = strings.TrimSpace(string(after))
			case bytes.Equal(before, dataKey):
				data := bytes.TrimSpace(after)
				if dataBuf != nil {
					dataBuf.WriteByte('\n')
					dataBuf.Write(data)
				} else {
					dataBuf = new(bytes.Buffer)
					dataBuf.Write(data)
				}
			}
		}
		if err := scanner.Err(); err != nil {
			if errors.Is(err, bufio.ErrTooLong) {
				err = fmt.Errorf("event exceeded max line length of %d", maxTokenSize)
			}
			if !yield(event{}, err) {
				return
			}
		}
		flushData()
		if !evt.empty() {
			yield(evt, nil)
		}
	}
}

// An sseClientConn is a logical jsonrpc2 connection that implements the client
// half of the SSE protocol:
//   - Writes are POSTS to the session endpoint.
//   - Reads are SSE 'message' events, and pushes them onto a buffered channel.
//   - Close terminates the GET request.
type sseClientConn struct {
	sseEndpoint *url.URL    // SSE endpoint for the GET
	msgEndpoint *url.URL    // session endpoint for POSTs
	incoming    chan []byte // queue of incoming messages

	mu     sync.Mutex
	body   io.ReadCloser // body of the hanging GET
	closed bool          // set when the stream is closed
	done   chan struct{} // closed when the stream is closed
}

func (c *sseClientConn) isDone() bool {
	c.mu.Lock()
	defer c.mu.Unlock()
	return c.closed
}

func (c *sseClientConn) Read(ctx context.Context) (JSONRPCMessage, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()

	case <-c.done:
		return nil, io.EOF

	case data := <-c.incoming:
		// TODO(rfindley): do we really need to check this? We receive from c.done above.
		if c.isDone() {
			return nil, io.EOF
		}
		msg, err := jsonrpc2.DecodeMessage(data)
		if err != nil {
			return nil, err
		}
		return msg, nil
	}
}

func (c *sseClientConn) Write(ctx context.Context, msg JSONRPCMessage) error {
	data, err := jsonrpc2.EncodeMessage(msg)
	if err != nil {
		return err
	}
	if c.isDone() {
		return io.EOF
	}
	req, err := http.NewRequestWithContext(ctx, "POST", c.msgEndpoint.String(), bytes.NewReader(data))
	if err != nil {
		return err
	}
	req.Header.Set("Content-Type", "application/json")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("failed to write: %s", resp.Status)
	}
	return nil
}

func (c *sseClientConn) Close() error {
	c.mu.Lock()
	defer c.mu.Unlock()
	if !c.closed {
		c.closed = true
		_ = c.body.Close()
		close(c.done)
	}
	return nil
}


================================================
FILE: internal/mcp/sse_example_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp_test

import (
	"context"
	"fmt"
	"log"
	"net/http"
	"net/http/httptest"

	"golang.org/x/tools/internal/mcp"
)

type AddParams struct {
	X, Y int
}

func Add(ctx context.Context, cc *mcp.ServerSession, params *mcp.CallToolParamsFor[AddParams]) (*mcp.CallToolResultFor[any], error) {
	return &mcp.CallToolResultFor[any]{
		Content: []*mcp.Content{mcp.NewTextContent(fmt.Sprintf("%d", params.Arguments.X+params.Arguments.Y))},
	}, nil
}

func ExampleSSEHandler() {
	server := mcp.NewServer("adder", "v0.0.1", nil)
	server.AddTools(mcp.NewServerTool("add", "add two numbers", Add))

	handler := mcp.NewSSEHandler(func(*http.Request) *mcp.Server { return server })
	httpServer := httptest.NewServer(handler)
	defer httpServer.Close()

	ctx := context.Background()
	transport := mcp.NewSSEClientTransport(httpServer.URL, nil)
	client := mcp.NewClient("test", "v1.0.0", nil)
	cs, err := client.Connect(ctx, transport)
	if err != nil {
		log.Fatal(err)
	}
	defer cs.Close()

	res, err := cs.CallTool(ctx, &mcp.CallToolParams{
		Name:      "add",
		Arguments: map[string]any{"x": 1, "y": 2},
	})
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(res.Content[0].Text)

	// Output: 3
}


================================================
FILE: internal/mcp/sse_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
)

func TestSSEServer(t *testing.T) {
	for _, closeServerFirst := range []bool{false, true} {
		t.Run(fmt.Sprintf("closeServerFirst=%t", closeServerFirst), func(t *testing.T) {
			ctx := context.Background()
			server := NewServer("testServer", "v1.0.0", nil)
			server.AddTools(NewServerTool("greet", "say hi", sayHi))

			sseHandler := NewSSEHandler(func(*http.Request) *Server { return server })

			conns := make(chan *ServerSession, 1)
			sseHandler.onConnection = func(cc *ServerSession) {
				select {
				case conns <- cc:
				default:
				}
			}
			httpServer := httptest.NewServer(sseHandler)
			defer httpServer.Close()

			clientTransport := NewSSEClientTransport(httpServer.URL, nil)

			c := NewClient("testClient", "v1.0.0", nil)
			cs, err := c.Connect(ctx, clientTransport)
			if err != nil {
				t.Fatal(err)
			}
			if err := cs.Ping(ctx, nil); err != nil {
				t.Fatal(err)
			}
			ss := <-conns
			gotHi, err := cs.CallTool(ctx, &CallToolParams{
				Name:      "greet",
				Arguments: map[string]any{"Name": "user"},
			})
			if err != nil {
				t.Fatal(err)
			}
			wantHi := &CallToolResult{
				Content: []*Content{{Type: "text", Text: "hi user"}},
			}
			if diff := cmp.Diff(wantHi, gotHi); diff != "" {
				t.Errorf("tools/call 'greet' mismatch (-want +got):\n%s", diff)
			}

			// Test that closing either end of the connection terminates the other
			// end.
			if closeServerFirst {
				cs.Close()
				ss.Wait()
			} else {
				ss.Close()
				cs.Wait()
			}
		})
	}
}

func TestScanEvents(t *testing.T) {
	tests := []struct {
		name    string
		input   string
		want    []event
		wantErr string
	}{
		{
			name:  "simple event",
			input: "event: message\nid: 1\ndata: hello\n\n",
			want: []event{
				{name: "message", id: "1", data: []byte("hello")},
			},
		},
		{
			name:  "multiple data lines",
			input: "data: line 1\ndata: line 2\n\n",
			want: []event{
				{data: []byte("line 1\nline 2")},
			},
		},
		{
			name:  "multiple events",
			input: "data: first\n\nevent: second\ndata: second\n\n",
			want: []event{
				{data: []byte("first")},
				{name: "second", data: []byte("second")},
			},
		},
		{
			name:  "no trailing newline",
			input: "data: hello",
			want: []event{
				{data: []byte("hello")},
			},
		},
		{
			name:    "malformed line",
			input:   "invalid line\n\n",
			wantErr: "malformed line",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			r := strings.NewReader(tt.input)
			var got []event
			var err error
			for e, err2 := range scanEvents(r) {
				if err2 != nil {
					err = err2
					break
				}
				got = append(got, e)
			}

			if tt.wantErr != "" {
				if err == nil {
					t.Fatalf("scanEvents() got nil error, want error containing %q", tt.wantErr)
				}
				if !strings.Contains(err.Error(), tt.wantErr) {
					t.Fatalf("scanEvents() error = %q, want containing %q", err, tt.wantErr)
				}
				return
			}

			if err != nil {
				t.Fatalf("scanEvents() returned unexpected error: %v", err)
			}

			if len(got) != len(tt.want) {
				t.Fatalf("scanEvents() got %d events, want %d", len(got), len(tt.want))
			}

			for i := range got {
				if g, w := got[i].name, tt.want[i].name; g != w {
					t.Errorf("event %d: name = %q, want %q", i, g, w)
				}
				if g, w := got[i].id, tt.want[i].id; g != w {
					t.Errorf("event %d: id = %q, want %q", i, g, w)
				}
				if g, w := string(got[i].data), string(tt.want[i].data); g != w {
					t.Errorf("event %d: data = %q, want %q", i, g, w)
				}
			}
		})
	}
}


================================================
FILE: internal/mcp/streamable.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"crypto/rand"
	"fmt"
	"io"
	"net/http"
	"strconv"
	"strings"
	"sync"
	"sync/atomic"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

// A StreamableHTTPHandler is an http.Handler that serves streamable MCP
// sessions, as defined by the [MCP spec].
//
// [MCP spec]: https://modelcontextprotocol.io/2025/03/26/streamable-http-transport.html
type StreamableHTTPHandler struct {
	getServer func(*http.Request) *Server

	sessionsMu sync.Mutex
	sessions   map[string]*StreamableServerTransport // keyed by IDs (from Mcp-Session-Id header)
}

// StreamableHTTPOptions is a placeholder options struct for future
// configuration of the StreamableHTTP handler.
type StreamableHTTPOptions struct {
	// TODO(rfindley): support configurable session ID generation and event
	// store, session retention, and event retention.
}

// NewStreamableHTTPHandler returns a new [StreamableHTTPHandler].
//
// The getServer function is used to create or look up servers for new
// sessions. It is OK for getServer to return the same server multiple times.
func NewStreamableHTTPHandler(getServer func(*http.Request) *Server, opts *StreamableHTTPOptions) *StreamableHTTPHandler {
	return &StreamableHTTPHandler{
		getServer: getServer,
		sessions:  make(map[string]*StreamableServerTransport),
	}
}

// closeAll closes all ongoing sessions.
//
// TODO(rfindley): investigate the best API for callers to configure their
// session lifecycle.
//
// Should we allow passing in a session store? That would allow the handler to
// be stateless.
func (h *StreamableHTTPHandler) closeAll() {
	h.sessionsMu.Lock()
	defer h.sessionsMu.Unlock()
	for _, s := range h.sessions {
		s.Close()
	}
	h.sessions = nil
}

func (h *StreamableHTTPHandler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	// Allow multiple 'Accept' headers.
	// https://developer.mozilla.org/en-US/docs/Web/HTTP/Reference/Headers/Accept#syntax
	accept := strings.Split(strings.Join(req.Header.Values("Accept"), ","), ",")
	var jsonOK, streamOK bool
	for _, c := range accept {
		switch strings.TrimSpace(c) {
		case "application/json":
			jsonOK = true
		case "text/event-stream":
			streamOK = true
		}
	}

	if req.Method == http.MethodGet {
		if !streamOK {
			http.Error(w, "Accept must contain 'text/event-stream' for GET requests", http.StatusBadRequest)
			return
		}
	} else if !jsonOK || !streamOK {
		http.Error(w, "Accept must contain both 'application/json' and 'text/event-stream'", http.StatusBadRequest)
		return
	}

	var session *StreamableServerTransport
	if id := req.Header.Get("Mcp-Session-Id"); id != "" {
		h.sessionsMu.Lock()
		session, _ = h.sessions[id]
		h.sessionsMu.Unlock()
		if session == nil {
			http.Error(w, "session not found", http.StatusNotFound)
			return
		}
	}

	// TODO(rfindley): simplify the locking so that each request has only one
	// critical section.
	if req.Method == http.MethodDelete {
		if session == nil {
			// => Mcp-Session-Id was not set; else we'd have returned NotFound above.
			http.Error(w, "DELETE requires an Mcp-Session-Id header", http.StatusBadRequest)
			return
		}
		h.sessionsMu.Lock()
		delete(h.sessions, session.id)
		h.sessionsMu.Unlock()
		session.Close()
		w.WriteHeader(http.StatusNoContent)
		return
	}

	switch req.Method {
	case http.MethodPost, http.MethodGet:
	default:
		w.Header().Set("Allow", "GET, POST")
		http.Error(w, "unsupported method", http.StatusMethodNotAllowed)
		return
	}

	if session == nil {
		s := NewStreamableServerTransport(rand.Text())
		server := h.getServer(req)
		// Pass req.Context() here, to allow middleware to add context values.
		// The context is detached in the jsonrpc2 library when handling the
		// long-running stream.
		if _, err := server.Connect(req.Context(), s); err != nil {
			http.Error(w, "failed connection", http.StatusInternalServerError)
			return
		}
		h.sessionsMu.Lock()
		h.sessions[s.id] = s
		h.sessionsMu.Unlock()
		session = s
	}

	session.ServeHTTP(w, req)
}

// NewStreamableServerTransport returns a new [StreamableServerTransport] with
// the given session ID.
//
// A StreamableServerTransport implements the server-side of the streamable
// transport.
//
// TODO(rfindley): consider adding options here, to configure event storage
// policy.
func NewStreamableServerTransport(sessionID string) *StreamableServerTransport {
	return &StreamableServerTransport{
		id:               sessionID,
		incoming:         make(chan JSONRPCMessage, 10),
		done:             make(chan struct{}),
		outgoingMessages: make(map[streamID][]*streamableMsg),
		signals:          make(map[streamID]chan struct{}),
		requestStreams:   make(map[JSONRPCID]streamID),
		streamRequests:   make(map[streamID]map[JSONRPCID]struct{}),
	}
}

// A StreamableServerTransport implements the [Transport] interface for a
// single session.
type StreamableServerTransport struct {
	nextStreamID atomic.Int64 // incrementing next stream ID

	id       string
	incoming chan JSONRPCMessage // messages from the client to the server

	mu sync.Mutex

	// Sessions are closed exactly once.
	isDone bool
	done   chan struct{}

	// Sessions can have multiple logical connections, corresponding to HTTP
	// requests. Additionally, logical sessions may be resumed by subsequent HTTP
	// requests, when the session is terminated unexpectedly.
	//
	// Therefore, we use a logical connection ID to key the connection state, and
	// perform the accounting described below when incoming HTTP requests are
	// handled.
	//
	// The accounting is complicated. It is tempting to merge some of the maps
	// below, but they each have different lifecycles, as indicated by Lifecycle:
	// comments.
	//
	// TODO(rfindley): simplify.

	// outgoingMessages is the collection of outgoingMessages messages, keyed by the logical
	// stream ID where they should be delivered.
	//
	// streamID 0 is used for messages that don't correlate with an incoming
	// request.
	//
	// Lifecycle: outgoingMessages persists for the duration of the session.
	//
	// TODO(rfindley): garbage collect this data. For now, we save all outgoingMessages
	// messages for the lifespan of the transport.
	outgoingMessages map[streamID][]*streamableMsg

	// signals maps a logical stream ID to a 1-buffered channel, owned by an
	// incoming HTTP request, that signals that there are messages available to
	// write into the HTTP response. Signals guarantees that at most one HTTP
	// response can receive messages for a logical stream. After claiming
	// the stream, incoming requests should read from outgoing, to ensure
	// that no new messages are missed.
	//
	// Lifecycle: signals persists for the duration of an HTTP POST or GET
	// request for the given streamID.
	signals map[streamID]chan struct{}

	// requestStreams maps incoming requests to their logical stream ID.
	//
	// Lifecycle: requestStreams persists for the duration of the session.
	//
	// TODO(rfindley): clean up once requests are handled.
	requestStreams map[JSONRPCID]streamID

	// outstandingRequests tracks the set of unanswered incoming RPCs for each logical
	// stream.
	//
	// When the server has responded to each request, the stream should be
	// closed.
	//
	// Lifecycle: outstandingRequests values persist as until the requests have been
	// replied to by the server. Notably, NOT until they are sent to an HTTP
	// response, as delivery is not guaranteed.
	streamRequests map[streamID]map[JSONRPCID]struct{}
}

type streamID int64

// a streamableMsg is an SSE event with an index into its logical stream.
type streamableMsg struct {
	idx   int
	event event
}

// Connect implements the [Transport] interface.
//
// TODO(rfindley): Connect should return a new object.
func (s *StreamableServerTransport) Connect(context.Context) (Connection, error) {
	return s, nil
}

// We track the incoming request ID inside the handler context using
// idContextValue, so that notifications and server->client calls that occur in
// the course of handling incoming requests are correlated with the incoming
// request that caused them, and can be dispatched as server-sent events to the
// correct HTTP request.
//
// Currently, this is implemented in [ServerSession.handle]. This is not ideal,
// because it means that a user of the MCP package couldn't implement the
// streamable transport, as they'd lack this priviledged access.
//
// If we ever wanted to expose this mechanism, we have a few options:
//  1. Make ServerSession an interface, and provide an implementation of
//     ServerSession to handlers that closes over the incoming request ID.
//  2. Expose a 'HandlerTransport' interface that allows transports to provide
//     a handler middleware, so that we don't hard-code this behavior in
//     ServerSession.handle.
//  3. Add a `func ForRequest(context.Context) JSONRPCID` accessor that lets
//     any transport access the incoming request ID.
//
// For now, by giving only the StreamableServerTransport access to the request
// ID, we avoid having to make this API decision.
type idContextKey struct{}

// ServeHTTP handles a single HTTP request for the session.
func (t *StreamableServerTransport) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	switch req.Method {
	case http.MethodGet:
		t.serveGET(w, req)
	case http.MethodPost:
		t.servePOST(w, req)
	default:
		// Should not be reached, as this is checked in StreamableHTTPHandler.ServeHTTP.
		w.Header().Set("Allow", "GET, POST")
		http.Error(w, "unsupported method", http.StatusMethodNotAllowed)
	}
}

func (t *StreamableServerTransport) serveGET(w http.ResponseWriter, req *http.Request) {
	// connID 0 corresponds to the default GET request.
	id, nextIdx := streamID(0), 0
	if len(req.Header.Values("Last-Event-ID")) > 0 {
		eid := req.Header.Get("Last-Event-ID")
		var ok bool
		id, nextIdx, ok = parseEventID(eid)
		if !ok {
			http.Error(w, fmt.Sprintf("malformed Last-Event-ID %q", eid), http.StatusBadRequest)
			return
		}
		nextIdx++
	}

	t.mu.Lock()
	if _, ok := t.signals[id]; ok {
		http.Error(w, "stream ID conflicts with ongoing stream", http.StatusBadRequest)
		t.mu.Unlock()
		return
	}
	signal := make(chan struct{}, 1)
	t.signals[id] = signal
	t.mu.Unlock()

	t.streamResponse(w, req, id, nextIdx, signal)
}

func (t *StreamableServerTransport) servePOST(w http.ResponseWriter, req *http.Request) {
	if len(req.Header.Values("Last-Event-ID")) > 0 {
		http.Error(w, "can't send Last-Event-ID for POST request", http.StatusBadRequest)
		return
	}

	// Read incoming messages.
	body, err := io.ReadAll(req.Body)
	if err != nil {
		http.Error(w, "failed to read body", http.StatusBadRequest)
		return
	}
	if len(body) == 0 {
		http.Error(w, "POST requires a non-empty body", http.StatusBadRequest)
		return
	}
	incoming, _, err := readBatch(body)
	if err != nil {
		http.Error(w, fmt.Sprintf("malformed payload: %v", err), http.StatusBadRequest)
		return
	}
	var requests = make(map[JSONRPCID]struct{})
	for _, msg := range incoming {
		if req, ok := msg.(*JSONRPCRequest); ok && req.ID.IsValid() {
			requests[req.ID] = struct{}{}
		}
	}

	// Update accounting for this request.
	id := streamID(t.nextStreamID.Add(1))
	signal := make(chan struct{}, 1)
	t.mu.Lock()
	if len(requests) > 0 {
		t.streamRequests[id] = make(map[JSONRPCID]struct{})
	}
	for reqID := range requests {
		t.requestStreams[reqID] = id
		t.streamRequests[id][reqID] = struct{}{}
	}
	t.signals[id] = signal
	t.mu.Unlock()

	// Publish incoming messages.
	for _, msg := range incoming {
		t.incoming <- msg
	}

	// TODO(rfindley): consider optimizing for a single incoming request, by
	// responding with application/json when there is only a single message in
	// the response.
	t.streamResponse(w, req, id, 0, signal)
}

func (t *StreamableServerTransport) streamResponse(w http.ResponseWriter, req *http.Request, id streamID, nextIndex int, signal chan struct{}) {
	defer func() {
		t.mu.Lock()
		delete(t.signals, id)
		t.mu.Unlock()
	}()

	// Stream resumption: adjust outgoing index based on what the user says
	// they've received.
	if nextIndex > 0 {
		t.mu.Lock()
		// Clamp nextIndex to outgoing messages.
		outgoing := t.outgoingMessages[id]
		if nextIndex > len(outgoing) {
			nextIndex = len(outgoing)
		}
		t.mu.Unlock()
	}

	w.Header().Set("Mcp-Session-Id", t.id)
	w.Header().Set("Content-Type", "text/event-stream") // Accept checked in [StreamableHTTPHandler]
	w.Header().Set("Cache-Control", "no-cache, no-transform")
	w.Header().Set("Connection", "keep-alive")

	writes := 0
stream:
	for {
		// Send outgoing messages
		t.mu.Lock()
		outgoing := t.outgoingMessages[id][nextIndex:]
		t.mu.Unlock()

		for _, msg := range outgoing {
			if _, err := writeEvent(w, msg.event); err != nil {
				// Connection closed or broken.
				return
			}
			writes++
			nextIndex++
		}

		t.mu.Lock()
		nOutstanding := len(t.streamRequests[id])
		nOutgoing := len(t.outgoingMessages[id])
		t.mu.Unlock()
		// If all requests have been handled and replied to, we can terminate this
		// connection. However, in the case of a sequencing violation from the server
		// (a send on the request context after the request has been handled), we
		// loop until we've written all messages.
		//
		// TODO(rfindley): should we instead refuse to send messages after the last
		// response? Decide, write a test, and change the behavior.
		if nextIndex < nOutgoing {
			continue // more to send
		}
		if req.Method == http.MethodPost && nOutstanding == 0 {
			if writes == 0 {
				// Spec: If the server accepts the input, the server MUST return HTTP
				// status code 202 Accepted with no body.
				w.WriteHeader(http.StatusAccepted)
			}
			return
		}

		select {
		case <-signal:
		case <-t.done:
			if writes == 0 {
				http.Error(w, "session terminated", http.StatusGone)
			}
			break stream
		case <-req.Context().Done():
			if writes == 0 {
				w.WriteHeader(http.StatusNoContent)
			}
			break stream
		}
	}
}

// Event IDs: encode both the logical connection ID and the index, as
// <streamID>_<idx>, to be consistent with the typescript implementation.

// formatEventID returns the event ID to use for the logical connection ID
// streamID and message index idx.
//
// See also [parseEventID].
func formatEventID(sid streamID, idx int) string {
	return fmt.Sprintf("%d_%d", sid, idx)
}

// parseEventID parses a Last-Event-ID value into a logical stream id and
// index.
//
// See also [formatEventID].
func parseEventID(eventID string) (sid streamID, idx int, ok bool) {
	parts := strings.Split(eventID, "_")
	if len(parts) != 2 {
		return 0, 0, false
	}
	stream, err := strconv.ParseInt(parts[0], 10, 64)
	if err != nil || stream < 0 {
		return 0, 0, false
	}
	idx, err = strconv.Atoi(parts[1])
	if err != nil || idx < 0 {
		return 0, 0, false
	}
	return streamID(stream), idx, true
}

// Read implements the [Connection] interface.
func (t *StreamableServerTransport) Read(ctx context.Context) (JSONRPCMessage, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case msg, ok := <-t.incoming:
		if !ok {
			return nil, io.EOF
		}
		return msg, nil
	case <-t.done:
		return nil, io.EOF
	}
}

// Write implements the [Connection] interface.
func (t *StreamableServerTransport) Write(ctx context.Context, msg JSONRPCMessage) error {
	// Find the incoming request that this write relates to, if any.
	var forRequest, replyTo JSONRPCID
	if resp, ok := msg.(*JSONRPCResponse); ok {
		// If the message is a response, it relates to its request (of course).
		forRequest = resp.ID
		replyTo = resp.ID
	} else {
		// Otherwise, we check to see if it request was made in the context of an
		// ongoing request. This may not be the case if the request way made with
		// an unrelated context.
		if v := ctx.Value(idContextKey{}); v != nil {
			forRequest = v.(JSONRPCID)
		}
	}

	// Find the logical connection corresponding to this request.
	//
	// For messages sent outside of a request context, this is the default
	// connection 0.
	var forConn streamID
	if forRequest.IsValid() {
		t.mu.Lock()
		forConn = t.requestStreams[forRequest]
		t.mu.Unlock()
	}

	data, err := jsonrpc2.EncodeMessage(msg)
	if err != nil {
		return err
	}

	t.mu.Lock()
	defer t.mu.Unlock()
	if t.isDone {
		return fmt.Errorf("session is closed") // TODO: should this be EOF?
	}

	if _, ok := t.streamRequests[forConn]; !ok && forConn != 0 {
		// No outstanding requests for this connection, which means it is logically
		// done. This is a sequencing violation from the server, so we should report
		// a side-channel error here. Put the message on the general queue to avoid
		// dropping messages.
		forConn = 0
	}

	idx := len(t.outgoingMessages[forConn])
	t.outgoingMessages[forConn] = append(t.outgoingMessages[forConn], &streamableMsg{
		idx: idx,
		event: event{
			name: "message",
			id:   formatEventID(forConn, idx),
			data: data,
		},
	})
	if replyTo.IsValid() {
		// Once we've put the reply on the queue, it's no longer outstanding.
		delete(t.streamRequests[forConn], replyTo)
		if len(t.streamRequests[forConn]) == 0 {
			delete(t.streamRequests, forConn)
		}
	}

	// Signal work.
	if c, ok := t.signals[forConn]; ok {
		select {
		case c <- struct{}{}:
		default:
		}
	}
	return nil
}

// Close implements the [Connection] interface.
func (t *StreamableServerTransport) Close() error {
	t.mu.Lock()
	defer t.mu.Unlock()
	if !t.isDone {
		t.isDone = true
		close(t.done)
	}
	return nil
}

// A StreamableClientTransport is a [Transport] that can communicate with an MCP
// endpoint serving the streamable HTTP transport defined by the 2025-03-26
// version of the spec.
//
// TODO(rfindley): support retries and resumption tokens.
type StreamableClientTransport struct {
	url  string
	opts StreamableClientTransportOptions
}

// StreamableClientTransportOptions provides options for the
// [NewStreamableClientTransport] constructor.
type StreamableClientTransportOptions struct {
	// HTTPClient is the client to use for making HTTP requests. If nil,
	// http.DefaultClient is used.
	HTTPClient *http.Client
}

// NewStreamableClientTransport returns a new client transport that connects to
// the streamable HTTP server at the provided URL.
func NewStreamableClientTransport(url string, opts *StreamableClientTransportOptions) *StreamableClientTransport {
	t := &StreamableClientTransport{url: url}
	if opts != nil {
		t.opts = *opts
	}
	return t
}

// Connect implements the [Transport] interface.
//
// The resulting [Connection] writes messages via POST requests to the
// transport URL with the Mcp-Session-Id header set, and reads messages from
// hanging requests.
//
// When closed, the connection issues a DELETE request to terminate the logical
// session.
func (t *StreamableClientTransport) Connect(ctx context.Context) (Connection, error) {
	client := t.opts.HTTPClient
	if client == nil {
		client = http.DefaultClient
	}
	return &streamableClientConn{
		url:      t.url,
		client:   client,
		incoming: make(chan []byte, 100),
		done:     make(chan struct{}),
	}, nil
}

type streamableClientConn struct {
	url       string
	sessionID string
	client    *http.Client
	incoming  chan []byte
	done      chan struct{}

	closeOnce sync.Once
	closeErr  error

	mu sync.Mutex
	// bodies map[*http.Response]io.Closer
	err error
}

// Read implements the [Connection] interface.
func (s *streamableClientConn) Read(ctx context.Context) (JSONRPCMessage, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	case <-s.done:
		return nil, io.EOF
	case data := <-s.incoming:
		return jsonrpc2.DecodeMessage(data)
	}
}

// Write implements the [Connection] interface.
func (s *streamableClientConn) Write(ctx context.Context, msg JSONRPCMessage) error {
	s.mu.Lock()
	if s.err != nil {
		s.mu.Unlock()
		return s.err
	}

	sessionID := s.sessionID
	if sessionID == "" {
		// Hold lock for the first request.
		defer s.mu.Unlock()
	} else {
		s.mu.Unlock()
	}

	gotSessionID, err := s.postMessage(ctx, sessionID, msg)
	if err != nil {
		if sessionID != "" {
			// unlocked; lock to set err
			s.mu.Lock()
			defer s.mu.Unlock()
		}
		if s.err != nil {
			s.err = err
		}
		return err
	}

	if sessionID == "" {
		// locked
		s.sessionID = gotSessionID
	}

	return nil
}

func (s *streamableClientConn) postMessage(ctx context.Context, sessionID string, msg JSONRPCMessage) (string, error) {
	data, err := jsonrpc2.EncodeMessage(msg)
	if err != nil {
		return "", err
	}

	req, err := http.NewRequestWithContext(ctx, http.MethodPost, s.url, bytes.NewReader(data))
	if err != nil {
		return "", err
	}
	if sessionID != "" {
		req.Header.Set("Mcp-Session-Id", sessionID)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Set("Accept", "application/json, text/event-stream")

	resp, err := s.client.Do(req)
	if err != nil {
		return "", err
	}

	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		// TODO: do a best effort read of the body here, and format it in the error.
		resp.Body.Close()
		return "", fmt.Errorf("broken session: %v", resp.Status)
	}

	sessionID = resp.Header.Get("Mcp-Session-Id")
	if resp.Header.Get("Content-Type") == "text/event-stream" {
		go s.handleSSE(resp)
	} else {
		resp.Body.Close()
	}
	return sessionID, nil
}

func (s *streamableClientConn) handleSSE(resp *http.Response) {
	defer resp.Body.Close()

	done := make(chan struct{})
	go func() {
		defer close(done)
		for evt, err := range scanEvents(resp.Body) {
			if err != nil {
				// TODO: surface this error; possibly break the stream
				return
			}
			s.incoming <- evt.data
		}
	}()

	select {
	case <-s.done:
	case <-done:
	}
}

// Close implements the [Connection] interface.
func (s *streamableClientConn) Close() error {
	s.closeOnce.Do(func() {
		close(s.done)

		req, err := http.NewRequest(http.MethodDelete, s.url, nil)
		if err != nil {
			s.closeErr = err
		} else {
			req.Header.Set("Mcp-Session-Id", s.sessionID)
			if _, err := s.client.Do(req); err != nil {
				s.closeErr = err
			}
		}
	})
	return s.closeErr
}


================================================
FILE: internal/mcp/streamable_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"io"
	"net/http"
	"net/http/cookiejar"
	"net/http/httptest"
	"net/url"
	"strings"
	"sync"
	"sync/atomic"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

func TestStreamableTransports(t *testing.T) {
	// This test checks that the streamable server and client transports can
	// communicate.

	ctx := context.Background()

	// 1. Create a server with a simple "greet" tool.
	server := NewServer("testServer", "v1.0.0", nil)
	server.AddTools(NewServerTool("greet", "say hi", sayHi))

	// 2. Start an httptest.Server with the StreamableHTTPHandler, wrapped in a
	// cookie-checking middleware.
	handler := NewStreamableHTTPHandler(func(req *http.Request) *Server { return server }, nil)
	httpServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		cookie, err := r.Cookie("test-cookie")
		if err != nil {
			t.Errorf("missing cookie: %v", err)
		} else if cookie.Value != "test-value" {
			t.Errorf("got cookie %q, want %q", cookie.Value, "test-value")
		}
		handler.ServeHTTP(w, r)
	}))
	defer httpServer.Close()

	// 3. Create a client and connect it to the server using our StreamableClientTransport.
	// Check that all requests honor a custom client.
	jar, err := cookiejar.New(nil)
	if err != nil {
		t.Fatal(err)
	}
	u, err := url.Parse(httpServer.URL)
	if err != nil {
		t.Fatal(err)
	}
	jar.SetCookies(u, []*http.Cookie{{Name: "test-cookie", Value: "test-value"}})
	httpClient := &http.Client{Jar: jar}
	transport := NewStreamableClientTransport(httpServer.URL, &StreamableClientTransportOptions{
		HTTPClient: httpClient,
	})
	client := NewClient("testClient", "v1.0.0", nil)
	session, err := client.Connect(ctx, transport)
	if err != nil {
		t.Fatalf("client.Connect() failed: %v", err)
	}
	defer session.Close()

	// 4. The client calls the "greet" tool.
	params := &CallToolParams{
		Name:      "greet",
		Arguments: map[string]any{"name": "streamy"},
	}
	got, err := session.CallTool(ctx, params)
	if err != nil {
		t.Fatalf("CallTool() failed: %v", err)
	}

	// 5. Verify that the correct response is received.
	want := &CallToolResult{
		Content: []*Content{{Type: "text", Text: "hi streamy"}},
	}
	if diff := cmp.Diff(want, got); diff != "" {
		t.Errorf("CallTool() returned unexpected content (-want +got):\n%s", diff)
	}
}

func TestStreamableServerTransport(t *testing.T) {
	// This test checks detailed behavior of the streamable server transport, by
	// faking the behavior of a streamable client using a sequence of HTTP
	// requests.

	// A step is a single step in the tests below, consisting of a request payload
	// and expected response.
	type step struct {
		// If OnRequest is > 0, this step only executes after a request with the
		// given ID is received.
		//
		// All OnRequest steps must occur before the step that creates the request.
		//
		// To avoid tests hanging when there's a bug, it's expected that this
		// request is received in the course of a *synchronous* request to the
		// server (otherwise, we wouldn't be able to terminate the test without
		// analyzing a dependency graph).
		OnRequest int64
		// If set, Async causes the step to run asynchronously to other steps.
		// Redundant with OnRequest: all OnRequest steps are asynchronous.
		Async bool

		Method     string           // HTTP request method
		Send       []JSONRPCMessage // messages to send
		CloseAfter int              // if nonzero, close after receiving this many messages
		StatusCode int              // expected status code
		Recv       []JSONRPCMessage // expected messages to receive
	}

	// JSON-RPC message constructors.
	req := func(id int64, method string, params any) *JSONRPCRequest {
		r := &JSONRPCRequest{
			Method: method,
			Params: mustMarshal(t, params),
		}
		if id > 0 {
			r.ID = jsonrpc2.Int64ID(id)
		}
		return r
	}
	resp := func(id int64, result any, err error) *JSONRPCResponse {
		return &JSONRPCResponse{
			ID:     jsonrpc2.Int64ID(id),
			Result: mustMarshal(t, result),
			Error:  err,
		}
	}

	// Predefined steps, to avoid repetition below.
	initReq := req(1, "initialize", &InitializeParams{})
	initResp := resp(1, &InitializeResult{
		Capabilities: &serverCapabilities{
			Logging:   &loggingCapabilities{},
			Prompts:   &promptCapabilities{ListChanged: true},
			Resources: &resourceCapabilities{ListChanged: true},
			Tools:     &toolCapabilities{ListChanged: true},
		},
		ProtocolVersion: "2025-03-26",
		ServerInfo:      &implementation{Name: "testServer", Version: "v1.0.0"},
	}, nil)
	initializedMsg := req(0, "initialized", &InitializedParams{})
	initialize := step{
		Method:     "POST",
		Send:       []JSONRPCMessage{initReq},
		StatusCode: http.StatusOK,
		Recv:       []JSONRPCMessage{initResp},
	}
	initialized := step{
		Method:     "POST",
		Send:       []JSONRPCMessage{initializedMsg},
		StatusCode: http.StatusAccepted,
	}

	tests := []struct {
		name  string
		tool  func(*testing.T, context.Context, *ServerSession)
		steps []step
	}{
		{
			name: "basic",
			steps: []step{
				initialize,
				initialized,
				{
					Method:     "POST",
					Send:       []JSONRPCMessage{req(2, "tools/call", &CallToolParams{Name: "tool"})},
					StatusCode: http.StatusOK,
					Recv:       []JSONRPCMessage{resp(2, &CallToolResult{}, nil)},
				},
			},
		},
		{
			name: "tool notification",
			tool: func(t *testing.T, ctx context.Context, ss *ServerSession) {
				// Send an arbitrary notification.
				if err := ss.NotifyProgress(ctx, &ProgressNotificationParams{}); err != nil {
					t.Errorf("Notify failed: %v", err)
				}
			},
			steps: []step{
				initialize,
				initialized,
				{
					Method: "POST",
					Send: []JSONRPCMessage{
						req(2, "tools/call", &CallToolParams{Name: "tool"}),
					},
					StatusCode: http.StatusOK,
					Recv: []JSONRPCMessage{
						req(0, "notifications/progress", &ProgressNotificationParams{}),
						resp(2, &CallToolResult{}, nil),
					},
				},
			},
		},
		{
			name: "tool upcall",
			tool: func(t *testing.T, ctx context.Context, ss *ServerSession) {
				// Make an arbitrary call.
				if _, err := ss.ListRoots(ctx, &ListRootsParams{}); err != nil {
					t.Errorf("Call failed: %v", err)
				}
			},
			steps: []step{
				initialize,
				initialized,
				{
					Method:    "POST",
					OnRequest: 1,
					Send: []JSONRPCMessage{
						resp(1, &ListRootsResult{}, nil),
					},
					StatusCode: http.StatusAccepted,
				},
				{
					Method: "POST",
					Send: []JSONRPCMessage{
						req(2, "tools/call", &CallToolParams{Name: "tool"}),
					},
					StatusCode: http.StatusOK,
					Recv: []JSONRPCMessage{
						req(1, "roots/list", &ListRootsParams{}),
						resp(2, &CallToolResult{}, nil),
					},
				},
			},
		},
		{
			name: "background",
			tool: func(t *testing.T, ctx context.Context, ss *ServerSession) {
				// Perform operations on a background context, and ensure the client
				// receives it.
				ctx = context.Background()
				if err := ss.NotifyProgress(ctx, &ProgressNotificationParams{}); err != nil {
					t.Errorf("Notify failed: %v", err)
				}
				// TODO(rfindley): finish implementing logging.
				// if err := ss.LoggingMessage(ctx, &LoggingMessageParams{}); err != nil {
				// 	t.Errorf("Logging failed: %v", err)
				// }
				if _, err := ss.ListRoots(ctx, &ListRootsParams{}); err != nil {
					t.Errorf("Notify failed: %v", err)
				}
			},
			steps: []step{
				initialize,
				initialized,
				{
					Method:    "POST",
					OnRequest: 1,
					Send: []JSONRPCMessage{
						resp(1, &ListRootsResult{}, nil),
					},
					StatusCode: http.StatusAccepted,
				},
				{
					Method:     "GET",
					Async:      true,
					StatusCode: http.StatusOK,
					CloseAfter: 2,
					Recv: []JSONRPCMessage{
						req(0, "notifications/progress", &ProgressNotificationParams{}),
						req(1, "roots/list", &ListRootsParams{}),
					},
				},
				{
					Method: "POST",
					Send: []JSONRPCMessage{
						req(2, "tools/call", &CallToolParams{Name: "tool"}),
					},
					StatusCode: http.StatusOK,
					Recv: []JSONRPCMessage{
						resp(2, &CallToolResult{}, nil),
					},
				},
			},
		},
		{
			name: "errors",
			steps: []step{
				{
					Method:     "PUT",
					StatusCode: http.StatusMethodNotAllowed,
				},
				{
					Method:     "DELETE",
					StatusCode: http.StatusBadRequest,
				},
				{
					Method:     "POST",
					Send:       []JSONRPCMessage{req(2, "tools/call", &CallToolParams{Name: "tool"})},
					StatusCode: http.StatusOK,
					Recv: []JSONRPCMessage{resp(2, nil, &jsonrpc2.WireError{
						Message: `method "tools/call" is invalid during session initialization`,
					})},
				},
			},
		},
	}

	for _, test := range tests {
		t.Run(test.name, func(t *testing.T) {
			// Create a server containing a single tool, which runs the test tool
			// behavior, if any.
			server := NewServer("testServer", "v1.0.0", nil)
			tool := NewServerTool("tool", "test tool", func(ctx context.Context, ss *ServerSession, params *CallToolParamsFor[any]) (*CallToolResultFor[any], error) {
				if test.tool != nil {
					test.tool(t, ctx, ss)
				}
				return &CallToolResultFor[any]{}, nil
			})
			server.AddTools(tool)

			// Start the streamable handler.
			handler := NewStreamableHTTPHandler(func(req *http.Request) *Server { return server }, nil)
			defer handler.closeAll()

			httpServer := httptest.NewServer(handler)
			defer httpServer.Close()

			// blocks records request blocks by JSONRPC ID.
			//
			// When an OnRequest step is encountered, it waits on the corresponding
			// block. When a request with that ID is received, the block is closed.
			var mu sync.Mutex
			blocks := make(map[int64]chan struct{})
			for _, step := range test.steps {
				if step.OnRequest > 0 {
					blocks[step.OnRequest] = make(chan struct{})
				}
			}

			// signal when all synchronous requests have executed, so we can fail
			// async requests that are blocked.
			syncRequestsDone := make(chan struct{})

			// To avoid complicated accounting for session ID, just set the first
			// non-empty session ID from a response.
			var sessionID atomic.Value
			sessionID.Store("")

			// doStep executes a single step.
			doStep := func(t *testing.T, step step) {
				if step.OnRequest > 0 {
					// Block the step until we've received the server->client request.
					mu.Lock()
					block := blocks[step.OnRequest]
					mu.Unlock()
					select {
					case <-block:
					case <-syncRequestsDone:
						t.Errorf("after all sync requests are complete, request still blocked on %d", step.OnRequest)
						return
					}
				}

				// Collect messages received during this request, unblock other steps
				// when requests are received.
				var got []JSONRPCMessage
				out := make(chan JSONRPCMessage)
				// Cancel the step if we encounter a request that isn't going to be
				// handled.
				ctx, cancel := context.WithCancel(context.Background())

				var wg sync.WaitGroup
				wg.Add(1)
				go func() {
					defer wg.Done()

					for m := range out {
						if req, ok := m.(*JSONRPCRequest); ok && req.ID.IsValid() {
							// Encountered a server->client request. We should have a
							// response queued. Otherwise, we may deadlock.
							mu.Lock()
							if block, ok := blocks[req.ID.Raw().(int64)]; ok {
								close(block)
							} else {
								t.Errorf("no queued response for %v", req.ID)
								cancel()
							}
							mu.Unlock()
						}
						got = append(got, m)
						if step.CloseAfter > 0 && len(got) == step.CloseAfter {
							cancel()
						}
					}
				}()

				gotSessionID, gotStatusCode, err := streamingRequest(ctx,
					httpServer.URL, sessionID.Load().(string), step.Method, step.Send, out)

				// Don't fail on cancelled requests: error (if any) is handled
				// elsewhere.
				if err != nil && ctx.Err() == nil {
					t.Fatal(err)
				}

				if gotStatusCode != step.StatusCode {
					t.Errorf("got status %d, want %d", gotStatusCode, step.StatusCode)
				}
				wg.Wait()

				transform := cmpopts.AcyclicTransformer("jsonrpcid", func(id JSONRPCID) any { return id.Raw() })
				if diff := cmp.Diff(step.Recv, got, transform); diff != "" {
					t.Errorf("received unexpected messages (-want +got):\n%s", diff)
				}
				sessionID.CompareAndSwap("", gotSessionID)
			}

			var wg sync.WaitGroup
			for _, step := range test.steps {
				if step.Async || step.OnRequest > 0 {
					wg.Add(1)
					go func() {
						defer wg.Done()
						doStep(t, step)
					}()
				} else {
					doStep(t, step)
				}
			}

			// Fail any blocked responses if they weren't needed by a synchronous
			// request.
			close(syncRequestsDone)

			wg.Wait()
		})
	}
}

// streamingRequest makes a request to the given streamable server with the
// given url, sessionID, and method.
//
// If provided, the in messages are encoded in the request body. A single
// message is encoded as a JSON object. Multiple messages are batched as a JSON
// array.
//
// Any received messages are sent to the out channel, which is closed when the
// request completes.
//
// Returns the sessionID and http status code from the response. If an error is
// returned, sessionID and status code may still be set if the error occurs
// after the response headers have been received.
func streamingRequest(ctx context.Context, serverURL, sessionID, method string, in []JSONRPCMessage, out chan<- JSONRPCMessage) (string, int, error) {
	defer close(out)

	var body []byte
	if len(in) == 1 {
		data, err := jsonrpc2.EncodeMessage(in[0])
		if err != nil {
			return "", 0, fmt.Errorf("encoding message: %w", err)
		}
		body = data
	} else {
		var rawMsgs []json.RawMessage
		for _, msg := range in {
			data, err := jsonrpc2.EncodeMessage(msg)
			if err != nil {
				return "", 0, fmt.Errorf("encoding message: %w", err)
			}
			rawMsgs = append(rawMsgs, data)
		}
		data, err := json.Marshal(rawMsgs)
		if err != nil {
			return "", 0, fmt.Errorf("marshaling batch: %w", err)
		}
		body = data
	}

	req, err := http.NewRequestWithContext(ctx, method, serverURL, bytes.NewReader(body))
	if err != nil {
		return "", 0, fmt.Errorf("creating request: %w", err)
	}
	if sessionID != "" {
		req.Header.Set("Mcp-Session-Id", sessionID)
	}
	req.Header.Set("Content-Type", "application/json")
	req.Header.Add("Accept", "text/plain") // ensure multiple accept headers are allowed
	req.Header.Add("Accept", "application/json, text/event-stream")

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return "", 0, fmt.Errorf("request failed: %v", err)
	}
	defer resp.Body.Close()

	newSessionID := resp.Header.Get("Mcp-Session-Id")

	if strings.HasPrefix(resp.Header.Get("Content-Type"), "text/event-stream") {
		for evt, err := range scanEvents(resp.Body) {
			if err != nil {
				return newSessionID, resp.StatusCode, fmt.Errorf("reading events: %v", err)
			}
			// TODO(rfindley): do we need to check evt.name?
			// Does the MCP spec say anything about this?
			msg, err := jsonrpc2.DecodeMessage(evt.data)
			if err != nil {
				return newSessionID, resp.StatusCode, fmt.Errorf("decoding message: %w", err)
			}
			out <- msg
		}
	} else if strings.HasPrefix(resp.Header.Get("Content-Type"), "application/json") {
		data, err := io.ReadAll(resp.Body)
		if err != nil {
			return newSessionID, resp.StatusCode, fmt.Errorf("reading json body: %w", err)
		}
		msg, err := jsonrpc2.DecodeMessage(data)
		if err != nil {
			return newSessionID, resp.StatusCode, fmt.Errorf("decoding message: %w", err)
		}
		out <- msg
	}

	return newSessionID, resp.StatusCode, nil
}

func mustMarshal(t *testing.T, v any) json.RawMessage {
	if v == nil {
		return nil
	}
	t.Helper()
	data, err := json.Marshal(v)
	if err != nil {
		t.Fatal(err)
	}
	return data
}

func TestEventID(t *testing.T) {
	tests := []struct {
		sid streamID
		idx int
	}{
		{0, 0},
		{0, 1},
		{1, 0},
		{1, 1},
		{1234, 5678},
	}

	for _, test := range tests {
		t.Run(fmt.Sprintf("%d_%d", test.sid, test.idx), func(t *testing.T) {
			eventID := formatEventID(test.sid, test.idx)
			gotSID, gotIdx, ok := parseEventID(eventID)
			if !ok {
				t.Fatalf("parseEventID(%q) failed, want ok", eventID)
			}
			if gotSID != test.sid || gotIdx != test.idx {
				t.Errorf("parseEventID(%q) = %d, %d, want %d, %d", eventID, gotSID, gotIdx, test.sid, test.idx)
			}
		})
	}

	invalid := []string{
		"",
		"_",
		"1_",
		"_1",
		"a_1",
		"1_a",
		"-1_1",
		"1_-1",
	}

	for _, eventID := range invalid {
		t.Run(fmt.Sprintf("invalid_%q", eventID), func(t *testing.T) {
			if _, _, ok := parseEventID(eventID); ok {
				t.Errorf("parseEventID(%q) succeeded, want failure", eventID)
			}
		})
	}
}


================================================
FILE: internal/mcp/testdata/conformance/server/prompts.txtar
================================================
Check behavior of a server with just prompts.

Fixed bugs:
- empty tools lists should not be returned as 'null'

-- prompts --
code_review

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2024-11-05",
    "capabilities": {},
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}
{ "jsonrpc": "2.0", "id": 2, "method": "tools/list" }
{ "jsonrpc": "2.0", "id": 4, "method": "prompts/list" }
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"_meta": {},
		"capabilities": {
			"completions": {},
			"logging": {},
			"prompts": {
				"listChanged": true
			},
			"resources": {
				"listChanged": true
			},
			"tools": {
				"listChanged": true
			}
		},
		"protocolVersion": "2024-11-05",
		"serverInfo": {
			"name": "testServer",
			"version": "v1.0.0"
		}
	}
}
{
	"jsonrpc": "2.0",
	"id": 2,
	"result": {
		"_meta": {},
		"tools": []
	}
}
{
	"jsonrpc": "2.0",
	"id": 4,
	"result": {
		"_meta": {},
		"prompts": [
			{
				"arguments": [
					{
						"name": "Code",
						"required": true
					}
				],
				"description": "do a code review",
				"name": "code_review"
			}
		]
	}
}


================================================
FILE: internal/mcp/testdata/conformance/server/resources.txtar
================================================
Check behavior of a server with just resources.

Fixed bugs:
- A resource result holds a slice of contents, not just one.

-- resources --
info
info.txt

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2024-11-05",
    "capabilities": {},
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}
{ "jsonrpc": "2.0", "id": 2, "method": "resources/list" }
{
  "jsonrpc": "2.0", "id": 3,
  "method": "resources/read",
  "params": {
    "uri": "embedded:info"
  }
}
{
  "jsonrpc": "2.0", "id": 3,
  "method": "resources/read",
  "params": {
    "uri": "file:///info.txt"
  }
}
{
  "jsonrpc": "2.0", "id": 0,
  "result": {
	"roots": []
  }
}
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"_meta": {},
		"capabilities": {
			"completions": {},
			"logging": {},
			"prompts": {
				"listChanged": true
			},
			"resources": {
				"listChanged": true
			},
			"tools": {
				"listChanged": true
			}
		},
		"protocolVersion": "2024-11-05",
		"serverInfo": {
			"name": "testServer",
			"version": "v1.0.0"
		}
	}
}
{
	"jsonrpc": "2.0",
	"id": 2,
	"result": {
		"_meta": {},
		"resources": [
			{
				"mimeType": "text/plain",
				"name": "info",
				"uri": "embedded:info"
			},
			{
				"mimeType": "text/plain",
				"name": "public",
				"uri": "file:///info.txt"
			}
		]
	}
}
{
	"jsonrpc": "2.0",
	"id": 3,
	"result": {
		"_meta": {},
		"contents": [
			{
				"uri": "embedded:info",
				"mimeType": "text/plain",
				"text": "This is the MCP test server."
			}
		]
	}
}
{
	"jsonrpc": "2.0",
	"id": 1,
	"method": "roots/list"
}
{
	"jsonrpc": "2.0",
	"id": 3,
	"result": {
		"_meta": {},
		"contents": [
			{
				"uri": "file:///info.txt",
				"mimeType": "text/plain",
				"blob": "Q29udGVudHMK"
			}
		]
	}
}


================================================
FILE: internal/mcp/testdata/conformance/server/tools.txtar
================================================
Check behavior of a server with just tools.

Fixed bugs:
- "tools/list" can have missing params
- "_meta" should not be nil
- empty resource or prompts should not be returned as 'null'

-- tools --
greet

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2024-11-05",
    "capabilities": {},
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}
{ "jsonrpc": "2.0", "id": 2, "method": "tools/list" }
{ "jsonrpc": "2.0", "id": 3, "method": "resources/list" }
{ "jsonrpc": "2.0", "id": 4, "method": "prompts/list" }
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"_meta": {},
		"capabilities": {
			"completions": {},
			"logging": {},
			"prompts": {
				"listChanged": true
			},
			"resources": {
				"listChanged": true
			},
			"tools": {
				"listChanged": true
			}
		},
		"protocolVersion": "2024-11-05",
		"serverInfo": {
			"name": "testServer",
			"version": "v1.0.0"
		}
	}
}
{
	"jsonrpc": "2.0",
	"id": 2,
	"result": {
		"_meta": {},
		"tools": [
			{
				"description": "say hi",
				"inputSchema": {
					"type": "object",
					"required": [
						"Name"
					],
					"properties": {
						"Name": {
							"type": "string"
						}
					},
					"additionalProperties": {
						"not": {}
					}
				},
				"name": "greet"
			}
		]
	}
}
{
	"jsonrpc": "2.0",
	"id": 3,
	"result": {
		"_meta": {},
		"resources": []
	}
}
{
	"jsonrpc": "2.0",
	"id": 4,
	"result": {
		"_meta": {},
		"prompts": []
	}
}


================================================
FILE: internal/mcp/testdata/conformance/server/version-latest.txtar
================================================
Check that when the client sends an arbitrary later version, the server
response with its latest supported version.

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2029-01-01",
    "capabilities": {},
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"_meta": {},
		"capabilities": {
			"completions": {},
			"logging": {},
			"prompts": {
				"listChanged": true
			},
			"resources": {
				"listChanged": true
			},
			"tools": {
				"listChanged": true
			}
		},
		"protocolVersion": "2025-03-26",
		"serverInfo": {
			"name": "testServer",
			"version": "v1.0.0"
		}
	}
}


================================================
FILE: internal/mcp/testdata/conformance/server/version-older.txtar
================================================
Check that when the client sends an older version, the server indicates
support.

-- client --
{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "initialize",
  "params": {
    "protocolVersion": "2024-11-05",
    "capabilities": {},
    "clientInfo": { "name": "ExampleClient", "version": "1.0.0" }
  }
}
-- server --
{
	"jsonrpc": "2.0",
	"id": 1,
	"result": {
		"_meta": {},
		"capabilities": {
			"completions": {},
			"logging": {},
			"prompts": {
				"listChanged": true
			},
			"resources": {
				"listChanged": true
			},
			"tools": {
				"listChanged": true
			}
		},
		"protocolVersion": "2024-11-05",
		"serverInfo": {
			"name": "testServer",
			"version": "v1.0.0"
		}
	}
}


================================================
FILE: internal/mcp/testdata/files/info.txt
================================================
Contents


================================================
FILE: internal/mcp/testdata/files/template.txt
================================================


================================================
FILE: internal/mcp/testdata/private.txt
================================================


================================================
FILE: internal/mcp/testdata/public/dir/file3.txt
================================================


================================================
FILE: internal/mcp/testdata/public/file1.txt
================================================


================================================
FILE: internal/mcp/testdata/public/file2.txt
================================================


================================================
FILE: internal/mcp/tool.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"bytes"
	"context"
	"encoding/json"
	"fmt"
	"slices"

	"golang.org/x/tools/internal/mcp/jsonschema"
)

// A ToolHandler handles a call to tools/call.
// [CallToolParams.Arguments] will contain a map[string]any that has been validated
// against the input schema.
// Perhaps this should be an alias for ToolHandlerFor[map[string]any, map[string]any].
type ToolHandler func(context.Context, *ServerSession, *CallToolParamsFor[map[string]any]) (*CallToolResult, error)

// A ToolHandlerFor handles a call to tools/call with typed arguments and results.
type ToolHandlerFor[In, Out any] func(context.Context, *ServerSession, *CallToolParamsFor[In]) (*CallToolResultFor[Out], error)

// A rawToolHandler is like a ToolHandler, but takes the arguments as json.RawMessage.
type rawToolHandler = func(context.Context, *ServerSession, *CallToolParamsFor[json.RawMessage]) (*CallToolResult, error)

// A Tool is a tool definition that is bound to a tool handler.
type ServerTool struct {
	Tool    *Tool
	Handler ToolHandler
	// Set in NewServerTool or Server.AddToolsErr.
	rawHandler rawToolHandler
	// Resolved tool schemas. Set in Server.AddToolsErr.
	// TODO(rfindley): re-enable schema validation. For now, it is causing breakage in Google.
	// inputResolved, outputResolved *jsonschema.Resolved
}

// NewServerTool is a helper to make a tool using reflection on the given type parameters.
// When the tool is called, CallToolParams.Arguments will be of type In.
//
// If provided, variadic [ToolOption] values may be used to customize the tool.
//
// The input schema for the tool is extracted from the request type for the
// handler, and used to unmmarshal and validate requests to the handler. This
// schema may be customized using the [Input] option.
func NewServerTool[In, Out any](name, description string, handler ToolHandlerFor[In, Out], opts ...ToolOption) *ServerTool {
	st, err := newServerToolErr[In, Out](name, description, handler, opts...)
	if err != nil {
		panic(fmt.Errorf("NewServerTool(%q): %w", name, err))
	}
	return st
}

func newServerToolErr[In, Out any](name, description string, handler ToolHandlerFor[In, Out], opts ...ToolOption) (*ServerTool, error) {
	// TODO: check that In is a struct.
	ischema, err := jsonschema.For[In]()
	if err != nil {
		return nil, err
	}
	// TODO: uncomment when output schemas drop.
	// oschema, err := jsonschema.For[TRes]()
	// if err != nil {
	// 	return nil, err
	// }

	t := &ServerTool{
		Tool: &Tool{
			Name:        name,
			Description: description,
			InputSchema: ischema,
			// OutputSchema: oschema,
		},
	}
	for _, opt := range opts {
		opt.set(t)
	}

	t.rawHandler = func(ctx context.Context, ss *ServerSession, rparams *CallToolParamsFor[json.RawMessage]) (*CallToolResult, error) {
		var args In
		if rparams.Arguments != nil {
			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
			if err := unmarshalSchema(rparams.Arguments, nil, &args); err != nil {
				return nil, err
			}
		}
		// TODO(jba): future-proof this copy.
		params := &CallToolParamsFor[In]{
			Meta:      rparams.Meta,
			Name:      rparams.Name,
			Arguments: args,
		}
		res, err := handler(ctx, ss, params)
		if err != nil {
			return nil, err
		}

		var ctr CallToolResult
		if res != nil {
			// TODO(jba): future-proof this copy.
			ctr.Meta = res.Meta
			ctr.Content = res.Content
			ctr.IsError = res.IsError
		}
		return &ctr, nil
	}
	return t, nil
}

// newRawHandler creates a rawToolHandler for tools not created through NewServerTool.
// It unmarshals the arguments into a map[string]any and validates them against the
// schema, then calls the ServerTool's handler.
func newRawHandler(st *ServerTool) rawToolHandler {
	if st.Handler == nil {
		panic("st.Handler is nil")
	}
	return func(ctx context.Context, ss *ServerSession, rparams *CallToolParamsFor[json.RawMessage]) (*CallToolResult, error) {
		// Unmarshal the args into what should be a map.
		var args map[string]any
		if rparams.Arguments != nil {
			// TODO(rfindley): re-enable schema validation. See note in [ServerTool].
			if err := unmarshalSchema(rparams.Arguments, nil, &args); err != nil {
				return nil, err
			}
		}
		// TODO: generate copy
		params := &CallToolParamsFor[map[string]any]{
			Meta:      rparams.Meta,
			Name:      rparams.Name,
			Arguments: args,
		}
		res, err := st.Handler(ctx, ss, params)
		// TODO(rfindley): investigate why server errors are embedded in this strange way,
		// rather than returned as jsonrpc2 server errors.
		if err != nil {
			return &CallToolResult{
				Content: []*Content{NewTextContent(err.Error())},
				IsError: true,
			}, nil
		}
		return res, nil
	}
}

// unmarshalSchema unmarshals data into v and validates the result according to
// the given resolved schema.
func unmarshalSchema(data json.RawMessage, resolved *jsonschema.Resolved, v any) error {
	// TODO: use reflection to create the struct type to unmarshal into.
	// Separate validation from assignment.

	// Disallow unknown fields.
	// Otherwise, if the tool was built with a struct, the client could send extra
	// fields and json.Unmarshal would ignore them, so the schema would never get
	// a chance to declare the extra args invalid.
	dec := json.NewDecoder(bytes.NewReader(data))
	dec.DisallowUnknownFields()
	if err := dec.Decode(v); err != nil {
		return fmt.Errorf("unmarshaling: %w", err)
	}
	// TODO: test with nil args.
	if resolved != nil {
		if err := resolved.ApplyDefaults(v); err != nil {
			return fmt.Errorf("applying defaults from \n\t%s\nto\n\t%s:\n%w", schemaJSON(resolved.Schema()), data, err)
		}
		if err := resolved.Validate(v); err != nil {
			return fmt.Errorf("validating\n\t%s\nagainst\n\t %s:\n %w", data, schemaJSON(resolved.Schema()), err)
		}
	}
	return nil
}

// A ToolOption configures the behavior of a Tool.
type ToolOption interface {
	set(*ServerTool)
}

type toolSetter func(*ServerTool)

func (s toolSetter) set(t *ServerTool) { s(t) }

// Input applies the provided [SchemaOption] configuration to the tool's input
// schema.
func Input(opts ...SchemaOption) ToolOption {
	return toolSetter(func(t *ServerTool) {
		for _, opt := range opts {
			opt.set(t.Tool.InputSchema)
		}
	})
}

// A SchemaOption configures a jsonschema.Schema.
type SchemaOption interface {
	set(s *jsonschema.Schema)
}

type schemaSetter func(*jsonschema.Schema)

func (s schemaSetter) set(schema *jsonschema.Schema) { s(schema) }

// Property configures the schema for the property of the given name.
// If there is no such property in the schema, it is created.
func Property(name string, opts ...SchemaOption) SchemaOption {
	return schemaSetter(func(schema *jsonschema.Schema) {
		propSchema, ok := schema.Properties[name]
		if !ok {
			propSchema = new(jsonschema.Schema)
			schema.Properties[name] = propSchema
		}
		// Apply the options, with special handling for Required, as it needs to be
		// set on the parent schema.
		for _, opt := range opts {
			if req, ok := opt.(required); ok {
				if req {
					if !slices.Contains(schema.Required, name) {
						schema.Required = append(schema.Required, name)
					}
				} else {
					schema.Required = slices.DeleteFunc(schema.Required, func(s string) bool {
						return s == name
					})
				}
			} else {
				opt.set(propSchema)
			}
		}
	})
}

// Required sets whether the associated property is required. It is only valid
// when used in a [Property] option: using Required outside of Property panics.
func Required(v bool) SchemaOption {
	return required(v)
}

// required must be a distinguished type as it needs special handling to mutate
// the parent schema, and to mutate prompt arguments.
type required bool

func (required) set(s *jsonschema.Schema) {
	panic("use of required outside of Property")
}

// Enum sets the provided values as the "enum" value of the schema.
func Enum(values ...any) SchemaOption {
	return schemaSetter(func(s *jsonschema.Schema) {
		s.Enum = values
	})
}

// Description sets the provided schema description.
func Description(desc string) SchemaOption {
	return description(desc)
}

// description must be a distinguished type so that it can be handled by prompt
// options.
type description string

func (d description) set(s *jsonschema.Schema) {
	s.Description = string(d)
}

// Schema overrides the inferred schema with a shallow copy of the given
// schema.
func Schema(schema *jsonschema.Schema) SchemaOption {
	return schemaSetter(func(s *jsonschema.Schema) {
		*s = *schema
	})
}

// schemaJSON returns the JSON value for s as a string, or a string indicating an error.
func schemaJSON(s *jsonschema.Schema) string {
	m, err := json.Marshal(s)
	if err != nil {
		return fmt.Sprintf("<!%s>", err)
	}
	return string(m)
}


================================================
FILE: internal/mcp/tool_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"encoding/json"
	"reflect"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"golang.org/x/tools/internal/mcp/jsonschema"
)

// testToolHandler is used for type inference in TestNewServerTool.
func testToolHandler[T any](context.Context, *ServerSession, *CallToolParamsFor[T]) (*CallToolResultFor[any], error) {
	panic("not implemented")
}

func TestNewServerTool(t *testing.T) {
	tests := []struct {
		tool *ServerTool
		want *jsonschema.Schema
	}{
		{
			NewServerTool("basic", "", testToolHandler[struct {
				Name string `json:"name"`
			}]),
			&jsonschema.Schema{
				Type:     "object",
				Required: []string{"name"},
				Properties: map[string]*jsonschema.Schema{
					"name": {Type: "string"},
				},
				AdditionalProperties: &jsonschema.Schema{Not: new(jsonschema.Schema)},
			},
		},
		{
			NewServerTool("enum", "", testToolHandler[struct{ Name string }], Input(
				Property("Name", Enum("x", "y", "z")),
			)),
			&jsonschema.Schema{
				Type:     "object",
				Required: []string{"Name"},
				Properties: map[string]*jsonschema.Schema{
					"Name": {Type: "string", Enum: []any{"x", "y", "z"}},
				},
				AdditionalProperties: &jsonschema.Schema{Not: new(jsonschema.Schema)},
			},
		},
		{
			NewServerTool("required", "", testToolHandler[struct {
				Name     string `json:"name"`
				Language string `json:"language"`
				X        int    `json:"x,omitempty"`
				Y        int    `json:"y,omitempty"`
			}], Input(
				Property("x", Required(true)))),
			&jsonschema.Schema{
				Type:     "object",
				Required: []string{"name", "language", "x"},
				Properties: map[string]*jsonschema.Schema{
					"language": {Type: "string"},
					"name":     {Type: "string"},
					"x":        {Type: "integer"},
					"y":        {Type: "integer"},
				},
				AdditionalProperties: &jsonschema.Schema{Not: new(jsonschema.Schema)},
			},
		},
		{
			NewServerTool("set_schema", "", testToolHandler[struct {
				X int `json:"x,omitempty"`
				Y int `json:"y,omitempty"`
			}], Input(
				Schema(&jsonschema.Schema{Type: "object"})),
			),
			&jsonschema.Schema{
				Type: "object",
			},
		},
	}
	for _, test := range tests {
		if diff := cmp.Diff(test.want, test.tool.Tool.InputSchema, cmpopts.IgnoreUnexported(jsonschema.Schema{})); diff != "" {
			t.Errorf("NewServerTool(%v) mismatch (-want +got):\n%s", test.tool.Tool.Name, diff)
		}
	}
}

func TestUnmarshalSchema(t *testing.T) {
	schema := &jsonschema.Schema{
		Type: "object",
		Properties: map[string]*jsonschema.Schema{
			"x": {Type: "integer", Default: json.RawMessage("3")},
		},
	}
	resolved, err := schema.Resolve(&jsonschema.ResolveOptions{ValidateDefaults: true})
	if err != nil {
		t.Fatal(err)
	}

	type S struct {
		X int `json:"x"`
	}

	for _, tt := range []struct {
		data string
		v    any
		want any
	}{
		{`{"x": 1}`, new(S), &S{X: 1}},
		{`{}`, new(S), &S{X: 3}},       // default applied
		{`{"x": 0}`, new(S), &S{X: 3}}, // FAIL: should be 0. (requires double unmarshal)
		{`{"x": 1}`, new(map[string]any), &map[string]any{"x": 1.0}},
		{`{}`, new(map[string]any), &map[string]any{"x": 3.0}}, // default applied
		{`{"x": 0}`, new(map[string]any), &map[string]any{"x": 0.0}},
	} {
		raw := json.RawMessage(tt.data)
		if err := unmarshalSchema(raw, resolved, tt.v); err != nil {
			t.Fatal(err)
		}
		if !reflect.DeepEqual(tt.v, tt.want) {
			t.Errorf("got %#v, want %#v", tt.v, tt.want)
		}

	}
}


================================================
FILE: internal/mcp/transport.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net"
	"os"
	"sync"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
	"golang.org/x/tools/internal/xcontext"
)

// ErrConnectionClosed is returned when sending a message to a connection that
// is closed or in the process of closing.
var ErrConnectionClosed = errors.New("connection closed")

// A Transport is used to create a bidirectional connection between MCP client
// and server.
//
// Transports should be used for at most one call to [Server.Connect] or
// [Client.Start].
type Transport interface {
	// Connect returns the logical JSON-RPC connection..
	//
	// It is called exactly once by [Server.Connect] or [Client.Connect].
	Connect(ctx context.Context) (Connection, error)
}

type (
	// JSONRPCID is a JSON-RPC request ID.
	JSONRPCID = jsonrpc2.ID
	// JSONRPCMessage is a JSON-RPC message.
	JSONRPCMessage = jsonrpc2.Message
	// JSONRPCRequest is a JSON-RPC request.
	JSONRPCRequest = jsonrpc2.Request
	// JSONRPCResponse is a JSON-RPC response.
	JSONRPCResponse = jsonrpc2.Response
)

// A Connection is a logical bidirectional JSON-RPC connection.
type Connection interface {
	Read(context.Context) (JSONRPCMessage, error)
	Write(context.Context, JSONRPCMessage) error
	Close() error // may be called concurrently by both peers
}

// A StdioTransport is a [Transport] that communicates over stdin/stdout using
// newline-delimited JSON.
type StdioTransport struct {
	ioTransport
}

// An ioTransport is a [Transport] that communicates using newline-delimited
// JSON over an io.ReadWriteCloser.
type ioTransport struct {
	rwc io.ReadWriteCloser
}

func (t *ioTransport) Connect(context.Context) (Connection, error) {
	return newIOConn(t.rwc), nil
}

// NewStdioTransport constructs a transport that communicates over
// stdin/stdout.
func NewStdioTransport() *StdioTransport {
	return &StdioTransport{ioTransport{rwc{os.Stdin, os.Stdout}}}
}

// An InMemoryTransport is a [Transport] that communicates over an in-memory
// network connection, using newline-delimited JSON.
type InMemoryTransport struct {
	ioTransport
}

// NewInMemoryTransports returns two InMemoryTransports that connect to each
// other.
func NewInMemoryTransports() (*InMemoryTransport, *InMemoryTransport) {
	c1, c2 := net.Pipe()
	return &InMemoryTransport{ioTransport{c1}}, &InMemoryTransport{ioTransport{c2}}
}

type binder[T handler] interface {
	bind(*jsonrpc2.Connection) T
	disconnect(T)
}

type handler interface {
	handle(ctx context.Context, req *JSONRPCRequest) (any, error)
}

func connect[H handler](ctx context.Context, t Transport, b binder[H]) (H, error) {
	var zero H
	conn, err := t.Connect(ctx)
	if err != nil {
		return zero, err
	}
	// If logging is configured, write message logs.
	reader, writer := jsonrpc2.Reader(conn), jsonrpc2.Writer(conn)
	var (
		h         H
		preempter canceller
	)
	bind := func(conn *jsonrpc2.Connection) jsonrpc2.Handler {
		h = b.bind(conn)
		preempter.conn = conn
		return jsonrpc2.HandlerFunc(h.handle)
	}
	_ = jsonrpc2.NewConnection(ctx, jsonrpc2.ConnectionConfig{
		Reader:    reader,
		Writer:    writer,
		Closer:    conn,
		Bind:      bind,
		Preempter: &preempter,
		OnDone: func() {
			b.disconnect(h)
		},
	})
	assert(preempter.conn != nil, "unbound preempter")
	return h, nil
}

// A canceller is a jsonrpc2.Preempter that cancels in-flight requests on MCP
// cancelled notifications.
type canceller struct {
	conn *jsonrpc2.Connection
}

// Preempt implements jsonrpc2.Preempter.
func (c *canceller) Preempt(ctx context.Context, req *JSONRPCRequest) (result any, err error) {
	if req.Method == "notifications/cancelled" {
		var params CancelledParams
		if err := json.Unmarshal(req.Params, &params); err != nil {
			return nil, err
		}
		id, err := jsonrpc2.MakeID(params.RequestID)
		if err != nil {
			return nil, err
		}
		go c.conn.Cancel(id)
	}
	return nil, jsonrpc2.ErrNotHandled
}

// call executes and awaits a jsonrpc2 call on the given connection,
// translating errors into the mcp domain.
func call(ctx context.Context, conn *jsonrpc2.Connection, method string, params Params, result Result) error {
	// TODO: the "%w"s in this function effectively make jsonrpc2.WireError part of the API.
	// Consider alternatives.
	call := conn.Call(ctx, method, params)
	err := call.Await(ctx, result)
	switch {
	case errors.Is(err, jsonrpc2.ErrClientClosing), errors.Is(err, jsonrpc2.ErrServerClosing):
		return fmt.Errorf("calling %q: %w", method, ErrConnectionClosed)
	case ctx.Err() != nil:
		// Notify the peer of cancellation.
		err := conn.Notify(xcontext.Detach(ctx), notificationCancelled, &CancelledParams{
			Reason:    ctx.Err().Error(),
			RequestID: call.ID().Raw(),
		})
		return errors.Join(ctx.Err(), err)
	case err != nil:
		return fmt.Errorf("calling %q: %w", method, err)
	}
	return nil
}

// A LoggingTransport is a [Transport] that delegates to another transport,
// writing RPC logs to an io.Writer.
type LoggingTransport struct {
	delegate Transport
	w        io.Writer
}

// NewLoggingTransport creates a new LoggingTransport that delegates to the
// provided transport, writing RPC logs to the provided io.Writer.
func NewLoggingTransport(delegate Transport, w io.Writer) *LoggingTransport {
	return &LoggingTransport{delegate, w}
}

// Connect connects the underlying transport, returning a [Connection] that writes
// logs to the configured destination.
func (t *LoggingTransport) Connect(ctx context.Context) (Connection, error) {
	delegate, err := t.delegate.Connect(ctx)
	if err != nil {
		return nil, err
	}
	return &loggingConn{delegate, t.w}, nil
}

type loggingConn struct {
	delegate Connection
	w        io.Writer
}

// loggingReader is a stream middleware that logs incoming messages.
func (s *loggingConn) Read(ctx context.Context) (JSONRPCMessage, error) {
	msg, err := s.delegate.Read(ctx)
	if err != nil {
		fmt.Fprintf(s.w, "read error: %v", err)
	} else {
		data, err := jsonrpc2.EncodeMessage(msg)
		if err != nil {
			fmt.Fprintf(s.w, "LoggingTransport: failed to marshal: %v", err)
		}
		fmt.Fprintf(s.w, "read: %s\n", string(data))
	}
	return msg, err
}

// loggingWriter is a stream middleware that logs outgoing messages.
func (s *loggingConn) Write(ctx context.Context, msg JSONRPCMessage) error {
	err := s.delegate.Write(ctx, msg)
	if err != nil {
		fmt.Fprintf(s.w, "write error: %v", err)
	} else {
		data, err := jsonrpc2.EncodeMessage(msg)
		if err != nil {
			fmt.Fprintf(s.w, "LoggingTransport: failed to marshal: %v", err)
		}
		fmt.Fprintf(s.w, "write: %s\n", string(data))
	}
	return err
}

func (s *loggingConn) Close() error {
	return s.delegate.Close()
}

// A rwc binds an io.ReadCloser and io.WriteCloser together to create an
// io.ReadWriteCloser.
type rwc struct {
	rc io.ReadCloser
	wc io.WriteCloser
}

func (r rwc) Read(p []byte) (n int, err error) {
	return r.rc.Read(p)
}

func (r rwc) Write(p []byte) (n int, err error) {
	return r.wc.Write(p)
}

func (r rwc) Close() error {
	return errors.Join(r.rc.Close(), r.wc.Close())
}

// An ioConn is a transport that delimits messages with newlines across
// a bidirectional stream, and supports JSONRPC2 message batching.
//
// See https://github.com/ndjson/ndjson-spec for discussion of newline
// delimited JSON.
//
// See [msgBatch] for more discussion of message batching.
type ioConn struct {
	rwc io.ReadWriteCloser // the underlying stream
	in  *json.Decoder      // a decoder bound to rwc

	// If outgoiBatch has a positive capacity, it will be used to batch requests
	// and notifications before sending.
	outgoingBatch []JSONRPCMessage

	// Unread messages in the last batch. Since reads are serialized, there is no
	// need to guard here.
	queue []JSONRPCMessage

	// batches correlate incoming requests to the batch in which they arrived.
	// Since writes may be concurrent to reads, we need to guard this with a mutex.
	batchMu sync.Mutex
	batches map[jsonrpc2.ID]*msgBatch // lazily allocated
}

func newIOConn(rwc io.ReadWriteCloser) *ioConn {
	return &ioConn{
		rwc: rwc,
		in:  json.NewDecoder(rwc),
	}
}

// addBatch records a msgBatch for an incoming batch payload.
// It returns an error if batch is malformed, containing previously seen IDs.
//
// See [msgBatch] for more.
func (t *ioConn) addBatch(batch *msgBatch) error {
	t.batchMu.Lock()
	defer t.batchMu.Unlock()
	for id := range batch.unresolved {
		if _, ok := t.batches[id]; ok {
			return fmt.Errorf("%w: batch contains previously seen request %v", jsonrpc2.ErrInvalidRequest, id.Raw())
		}
	}
	for id := range batch.unresolved {
		if t.batches == nil {
			t.batches = make(map[jsonrpc2.ID]*msgBatch)
		}
		t.batches[id] = batch
	}
	return nil
}

// updateBatch records a response in the message batch tracking the
// corresponding incoming call, if any.
//
// The second result reports whether resp was part of a batch. If this is true,
// the first result is nil if the batch is still incomplete, or the full set of
// batch responses if resp completed the batch.
func (t *ioConn) updateBatch(resp *JSONRPCResponse) ([]*JSONRPCResponse, bool) {
	t.batchMu.Lock()
	defer t.batchMu.Unlock()

	if batch, ok := t.batches[resp.ID]; ok {
		idx, ok := batch.unresolved[resp.ID]
		if !ok {
			panic("internal error: inconsistent batches")
		}
		batch.responses[idx] = resp
		delete(batch.unresolved, resp.ID)
		delete(t.batches, resp.ID)
		if len(batch.unresolved) == 0 {
			return batch.responses, true
		}
		return nil, true
	}
	return nil, false
}

// A msgBatch records information about an incoming batch of JSONRPC2 calls.
//
// The JSONRPC2 spec (https://www.jsonrpc.org/specification#batch) says:
//
// "The Server should respond with an Array containing the corresponding
// Response objects, after all of the batch Request objects have been
// processed. A Response object SHOULD exist for each Request object, except
// that there SHOULD NOT be any Response objects for notifications. The Server
// MAY process a batch rpc call as a set of concurrent tasks, processing them
// in any order and with any width of parallelism."
//
// Therefore, a msgBatch keeps track of outstanding calls and their responses.
// When there are no unresolved calls, the response payload is sent.
type msgBatch struct {
	unresolved map[jsonrpc2.ID]int
	responses  []*JSONRPCResponse
}

func (t *ioConn) Read(ctx context.Context) (JSONRPCMessage, error) {
	return t.read(ctx, t.in)
}

func (t *ioConn) read(ctx context.Context, in *json.Decoder) (JSONRPCMessage, error) {
	select {
	case <-ctx.Done():
		return nil, ctx.Err()
	default:
	}
	if len(t.queue) > 0 {
		next := t.queue[0]
		t.queue = t.queue[1:]
		return next, nil
	}

	var raw json.RawMessage
	if err := in.Decode(&raw); err != nil {
		return nil, err
	}
	msgs, batch, err := readBatch(raw)
	if err != nil {
		return nil, err
	}
	t.queue = msgs[1:]

	if batch {
		var respBatch *msgBatch // track incoming requests in the batch
		for _, msg := range msgs {
			if req, ok := msg.(*JSONRPCRequest); ok {
				if respBatch == nil {
					respBatch = &msgBatch{
						unresolved: make(map[jsonrpc2.ID]int),
					}
				}
				if _, ok := respBatch.unresolved[req.ID]; ok {
					return nil, fmt.Errorf("duplicate message ID %q", req.ID)
				}
				respBatch.unresolved[req.ID] = len(respBatch.responses)
				respBatch.responses = append(respBatch.responses, nil)
			}
		}
		if respBatch != nil {
			// The batch contains one or more incoming requests to track.
			if err := t.addBatch(respBatch); err != nil {
				return nil, err
			}
		}
	}
	return msgs[0], err
}

// readBatch reads batch data, which may be either a single JSON-RPC message,
// or an array of JSON-RPC messages.
func readBatch(data []byte) (msgs []JSONRPCMessage, isBatch bool, _ error) {
	// Try to read an array of messages first.
	var rawBatch []json.RawMessage
	if err := json.Unmarshal(data, &rawBatch); err == nil {
		if len(rawBatch) == 0 {
			return nil, true, fmt.Errorf("empty batch")
		}
		for _, raw := range rawBatch {
			msg, err := jsonrpc2.DecodeMessage(raw)
			if err != nil {
				return nil, true, err
			}
			msgs = append(msgs, msg)
		}
		return msgs, true, nil
	}
	// Try again with a single message.
	msg, err := jsonrpc2.DecodeMessage(data)
	return []JSONRPCMessage{msg}, false, err
}

func (t *ioConn) Write(ctx context.Context, msg JSONRPCMessage) error {
	select {
	case <-ctx.Done():
		return ctx.Err()
	default:
	}

	// Batching support: if msg is a Response, it may have completed a batch, so
	// check that first. Otherwise, it is a request or notification, and we may
	// want to collect it into a batch before sending, if we're configured to use
	// outgoing batches.
	if resp, ok := msg.(*JSONRPCResponse); ok {
		if batch, ok := t.updateBatch(resp); ok {
			if len(batch) > 0 {
				data, err := marshalMessages(batch)
				if err != nil {
					return err
				}
				data = append(data, '\n')
				_, err = t.rwc.Write(data)
				return err
			}
			return nil
		}
	} else if len(t.outgoingBatch) < cap(t.outgoingBatch) {
		t.outgoingBatch = append(t.outgoingBatch, msg)
		if len(t.outgoingBatch) == cap(t.outgoingBatch) {
			data, err := marshalMessages(t.outgoingBatch)
			t.outgoingBatch = t.outgoingBatch[:0]
			if err != nil {
				return err
			}
			data = append(data, '\n')
			_, err = t.rwc.Write(data)
			return err
		}
		return nil
	}
	data, err := jsonrpc2.EncodeMessage(msg)
	if err != nil {
		return fmt.Errorf("marshaling message: %v", err)
	}
	data = append(data, '\n') // newline delimited
	_, err = t.rwc.Write(data)
	return err
}

func (t *ioConn) Close() error {
	return t.rwc.Close()
}

func marshalMessages[T JSONRPCMessage](msgs []T) ([]byte, error) {
	var rawMsgs []json.RawMessage
	for _, msg := range msgs {
		raw, err := jsonrpc2.EncodeMessage(msg)
		if err != nil {
			return nil, fmt.Errorf("encoding batch message: %w", err)
		}
		rawMsgs = append(rawMsgs, raw)
	}
	return json.Marshal(rawMsgs)
}


================================================
FILE: internal/mcp/transport_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"context"
	"io"
	"testing"

	jsonrpc2 "golang.org/x/tools/internal/jsonrpc2_v2"
)

func TestBatchFraming(t *testing.T) {
	// This test checks that the ndjsonFramer can read and write JSON batches.
	//
	// The framer is configured to write a batch size of 2, and we confirm that
	// nothing is sent over the wire until the second write, at which point both
	// messages become available.
	ctx := context.Background()

	r, w := io.Pipe()
	tport := newIOConn(rwc{r, w})
	tport.outgoingBatch = make([]JSONRPCMessage, 0, 2)

	// Read the two messages into a channel, for easy testing later.
	read := make(chan JSONRPCMessage)
	go func() {
		for range 2 {
			msg, _ := tport.Read(ctx)
			read <- msg
		}
	}()

	// The first write should not yet be observed by the reader.
	tport.Write(ctx, &JSONRPCRequest{ID: jsonrpc2.Int64ID(1), Method: "test"})
	select {
	case got := <-read:
		t.Fatalf("after one write, got message %v", got)
	default:
	}

	// ...but the second write causes both messages to be observed.
	tport.Write(ctx, &JSONRPCRequest{ID: jsonrpc2.Int64ID(2), Method: "test"})
	for _, want := range []int64{1, 2} {
		got := <-read
		if got := got.(*JSONRPCRequest).ID.Raw(); got != want {
			t.Errorf("got message #%d, want #%d", got, want)
		}
	}
}


================================================
FILE: internal/mcp/util.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"encoding/json"
	"fmt"
	"reflect"
	"sync"

	"golang.org/x/tools/internal/mcp/internal/util"
)

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

// marshalStructWithMap marshals its first argument to JSON, treating the field named
// mapField as an embedded map. The first argument must be a pointer to
// a struct. The underlying type of mapField must be a map[string]any, and it must have
// an "omitempty" json tag.
//
// For example, given this struct:
//
//	type S struct {
//	   A int
//	   Extra map[string] any `json:,omitempty`
//	}
//
// and this value:
//
//	s := S{A: 1, Extra: map[string]any{"B": 2}}
//
// the call marshalJSONWithMap(s, "Extra") would return
//
//	{"A": 1, "B": 2}
//
// It is an error if the map contains the same key as another struct field's
// JSON name.
//
// marshalStructWithMap calls json.Marshal on a value of type T, so T must not
// have a MarshalJSON method that calls this function, on pain of infinite regress.
//
// TODO: avoid this restriction on T by forcing it to marshal in a default way.
// See https://go.dev/play/p/EgXKJHxEx_R.
func marshalStructWithMap[T any](s *T, mapField string) ([]byte, error) {
	// Marshal the struct and the map separately, and concatenate the bytes.
	// This strategy is dramatically less complicated than
	// constructing a synthetic struct or map with the combined keys.
	if s == nil {
		return []byte("null"), nil
	}
	s2 := *s
	vMapField := reflect.ValueOf(&s2).Elem().FieldByName(mapField)
	mapVal := vMapField.Interface().(map[string]any)

	// Check for duplicates.
	names := jsonNames(reflect.TypeFor[T]())
	for key := range mapVal {
		if names[key] {
			return nil, fmt.Errorf("map key %q duplicates struct field", key)
		}
	}

	// Clear the map field, relying on the omitempty tag to omit it.
	vMapField.Set(reflect.Zero(vMapField.Type()))
	structBytes, err := json.Marshal(s2)
	if err != nil {
		return nil, fmt.Errorf("marshalStructWithMap(%+v): %w", s, err)
	}
	if len(mapVal) == 0 {
		return structBytes, nil
	}
	mapBytes, err := json.Marshal(mapVal)
	if err != nil {
		return nil, err
	}
	if len(structBytes) == 2 { // must be "{}"
		return mapBytes, nil
	}
	// "{X}" + "{Y}" => "{X,Y}"
	res := append(structBytes[:len(structBytes)-1], ',')
	res = append(res, mapBytes[1:]...)
	return res, nil
}

// unmarshalStructWithMap is the inverse of marshalStructWithMap.
// T has the same restrictions as in that function.
func unmarshalStructWithMap[T any](data []byte, v *T, mapField string) error {
	// Unmarshal into the struct, ignoring unknown fields.
	if err := json.Unmarshal(data, v); err != nil {
		return err
	}
	// Unmarshal into the map.
	m := map[string]any{}
	if err := json.Unmarshal(data, &m); err != nil {
		return err
	}
	// Delete from the map the fields of the struct.
	for n := range jsonNames(reflect.TypeFor[T]()) {
		delete(m, n)
	}
	if len(m) != 0 {
		reflect.ValueOf(v).Elem().FieldByName(mapField).Set(reflect.ValueOf(m))
	}
	return nil
}

var jsonNamesMap sync.Map // from reflect.Type to map[string]bool

// jsonNames returns the set of JSON object keys that t will marshal into.
// t must be a struct type.
func jsonNames(t reflect.Type) map[string]bool {
	// Lock not necessary: at worst we'll duplicate work.
	if val, ok := jsonNamesMap.Load(t); ok {
		return val.(map[string]bool)
	}
	m := map[string]bool{}
	for i := range t.NumField() {
		info := util.FieldJSONInfo(t.Field(i))
		if !info.Omit {
			m[info.Name] = true
		}
	}
	jsonNamesMap.Store(t, m)
	return m
}


================================================
FILE: internal/mcp/util_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package mcp

import (
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
)

func TestMarshalStructWithMap(t *testing.T) {
	type S struct {
		A int
		B string `json:"b,omitempty"`
		u bool
		M map[string]any `json:",omitempty"`
	}
	t.Run("basic", func(t *testing.T) {
		s := S{A: 1, B: "two", M: map[string]any{"!@#": true}}
		got, err := marshalStructWithMap(&s, "M")
		if err != nil {
			t.Fatal(err)
		}
		want := `{"A":1,"b":"two","!@#":true}`
		if g := string(got); g != want {
			t.Errorf("\ngot  %s\nwant %s", g, want)
		}

		var un S
		if err := unmarshalStructWithMap(got, &un, "M"); err != nil {
			t.Fatal(err)
		}
		if diff := cmp.Diff(s, un, cmpopts.IgnoreUnexported(S{})); diff != "" {
			t.Errorf("mismatch (-want, +got):\n%s", diff)
		}
	})
	t.Run("duplicate", func(t *testing.T) {
		s := S{A: 1, B: "two", M: map[string]any{"b": "dup"}}
		_, err := marshalStructWithMap(&s, "M")
		if err == nil || !strings.Contains(err.Error(), "duplicate") {
			t.Errorf("got %v, want error with 'duplicate'", err)
		}
	})
}


================================================
FILE: internal/modindex/dir_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex_test

import (
	"os"
	"path/filepath"
	"testing"

	"github.com/google/go-cmp/cmp"

	. "golang.org/x/tools/internal/modindex"
)

type id struct {
	importPath string
	best       int // which of the dirs is the one that should have been chosen
	dirs       []string
}

var idtests = []id{
	{ // get one right
		importPath: "cloud.google.com/go/longrunning",
		best:       2,
		dirs: []string{
			"cloud.google.com/go/longrunning@v0.3.0",
			"cloud.google.com/go/longrunning@v0.4.1",
			"cloud.google.com/go@v0.104.0/longrunning",
			"cloud.google.com/go@v0.94.0/longrunning",
		},
	},
	{ // make sure we can run more than one test
		importPath: "cloud.google.com/go/compute/metadata",
		best:       2,
		dirs: []string{
			"cloud.google.com/go/compute/metadata@v0.2.1",
			"cloud.google.com/go/compute/metadata@v0.2.3",
			"cloud.google.com/go/compute@v1.7.0/metadata",
			"cloud.google.com/go@v0.94.0/compute/metadata",
		},
	},
	{ // test bizarre characters in directory name
		importPath: "bad,guy.com/go",
		best:       0,
		dirs:       []string{"bad,guy.com/go@v0.1.0"},
	},
}

func testModCache(t *testing.T) string {
	IndexDir = t.TempDir()
	return IndexDir
}

// add a trivial package to the test module cache
func addPkg(gomodcache, dir string) error {
	if err := os.MkdirAll(filepath.Join(gomodcache, dir), 0755); err != nil {
		return err
	}
	return os.WriteFile(filepath.Join(gomodcache, dir, "foo.go"),
		[]byte("package foo\nfunc Foo() {}"), 0644)
}

// update, where new stuff is semantically better than old stuff
func TestIncremental(t *testing.T) {
	dir := testModCache(t)
	// build old index
	for _, it := range idtests {
		for i, d := range it.dirs {
			if it.best == i {
				continue // wait for second pass
			}
			if err := addPkg(dir, d); err != nil {
				t.Fatal(err)
			}
		}
	}
	index0, err := Create(dir)
	if err != nil {
		t.Fatal(err)
	}
	// add new stuff to the module cache
	for _, it := range idtests {
		for i, d := range it.dirs {
			if it.best != i {
				continue // only add the new stuff
			}
			if err := addPkg(dir, d); err != nil {
				t.Fatal(err)
			}
		}
	}
	if index1, err := Update(dir); err != nil {
		t.Fatalf("failed to update index: %v", err)
	} else if len(index1.Entries) <= len(index0.Entries) {
		t.Fatalf("updated index is not larger: %v", err)
	}
	index2, err := Read(dir)
	if err != nil {
		t.Fatal(err)
	}
	// build a fresh index
	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	index1, err := Read(dir)
	if err != nil {
		t.Fatal(err)
	}
	// they should be the same except maybe for the time
	index1.ValidAt = index2.ValidAt
	if diff := cmp.Diff(index1, index2); diff != "" {
		t.Errorf("mismatching indexes (-updated +cleared):\n%s", diff)
	}
}

// update, where new stuff is semantically worse than some old stuff
func TestIncrementalNope(t *testing.T) {
	dir := testModCache(t)
	// build old index
	for _, it := range idtests {
		for i, d := range it.dirs {
			if i == 0 {
				continue // wait for second pass
			}
			if err := addPkg(dir, d); err != nil {
				t.Fatal(err)
			}
		}
	}
	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	// add new stuff to the module cache
	for _, it := range idtests {
		for i, d := range it.dirs {
			if i > 0 {
				break // only add the new one
			}
			if err := addPkg(dir, d); err != nil {
				t.Fatal(err)
			}
		}
	}
	index2, err := Update(dir)
	if err != nil {
		t.Fatal(err)
	}
	// build a fresh index
	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	index1, err := Read(dir)
	if err != nil {
		t.Fatal(err)
	}
	// they should be the same except maybe for the time
	index1.ValidAt = index2.ValidAt
	if diff := cmp.Diff(index1, index2); diff != "" {
		t.Errorf("mismatching indexes (-updated +cleared):\n%s", diff)
	}
}

// choose the semantically-latest version, with a single symbol
func TestDirsSinglePath(t *testing.T) {
	for _, itest := range idtests {
		t.Run(itest.importPath, func(t *testing.T) {
			// create a new test GOMODCACHE
			dir := testModCache(t)
			for _, d := range itest.dirs {
				if err := addPkg(dir, d); err != nil {
					t.Fatal(err)
				}
			}
			// build and check the index
			if _, err := Create(dir); err != nil {
				t.Fatal(err)
			}
			ix, err := Read(dir)
			if err != nil {
				t.Fatal(err)
			}
			if len(ix.Entries) != 1 {
				t.Fatalf("got %d entries, wanted 1", len(ix.Entries))
			}
			if ix.Entries[0].ImportPath != itest.importPath {
				t.Fatalf("got %s import path, wanted %s", ix.Entries[0].ImportPath, itest.importPath)
			}
			gotDir := filepath.ToSlash(ix.Entries[0].Dir)
			if gotDir != itest.dirs[itest.best] {
				t.Fatalf("got dir %s, wanted %s", gotDir, itest.dirs[itest.best])
			}
			nms := ix.Entries[0].Names
			if len(nms) != 1 {
				t.Fatalf("got %d names, expected 1", len(nms))
			}
			if nms[0] != "Foo F 0" {
				t.Fatalf("got %q, expected Foo F 0", nms[0])
			}
		})
	}
}

func TestMissingGOMODCACHE(t *testing.T) {
	// behave properly if the cached dir is empty
	dir := testModCache(t)
	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	des, err := os.ReadDir(IndexDir)
	if err != nil {
		t.Fatal(err)
	}
	if len(des) != 2 {
		t.Errorf("got %d, but expected two entries in index dir", len(des))
	}
}

func TestMissingIndex(t *testing.T) {
	// behave properly if there is no existing index
	dir := testModCache(t)
	if _, err := Update(dir); err != nil {
		t.Fatal(err)
	}
	des, err := os.ReadDir(IndexDir)
	if err != nil {
		t.Fatal(err)
	}
	if len(des) != 2 {
		t.Errorf("got %d, but expected two entries in index dir", len(des))
	}
}


================================================
FILE: internal/modindex/directories.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"regexp"
	"strings"
	"sync"
	"time"

	"golang.org/x/mod/semver"
	"golang.org/x/tools/internal/gopathwalk"
)

type directory struct {
	path       string // relative to GOMODCACHE
	importPath string
	version    string // semantic version
}

// bestDirByImportPath returns the best directory for each import
// path, where "best" means most recent semantic version. These import
// paths are inferred from the GOMODCACHE-relative dir names in dirs.
func bestDirByImportPath(dirs []string) (map[string]directory, error) {
	dirsByPath := make(map[string]directory)
	for _, dir := range dirs {
		importPath, version, err := dirToImportPathVersion(dir)
		if err != nil {
			return nil, err
		}
		new := directory{
			path:       dir,
			importPath: importPath,
			version:    version,
		}
		if old, ok := dirsByPath[importPath]; !ok || compareDirectory(new, old) < 0 {
			dirsByPath[importPath] = new
		}
	}
	return dirsByPath, nil
}

// compareDirectory defines an ordering of path@version directories,
// by descending version, then by ascending path.
func compareDirectory(x, y directory) int {
	if sign := -semver.Compare(x.version, y.version); sign != 0 {
		return sign // latest first
	}
	return strings.Compare(string(x.path), string(y.path))
}

// modCacheRegexp splits a relpathpath into module, module version, and package.
var modCacheRegexp = regexp.MustCompile(`(.*)@([^/\\]*)(.*)`)

// dirToImportPathVersion computes import path and semantic version
// from a GOMODCACHE-relative directory name.
func dirToImportPathVersion(dir string) (string, string, error) {
	m := modCacheRegexp.FindStringSubmatch(string(dir))
	// m[1] is the module path
	// m[2] is the version major.minor.patch(-<pre release identifier)
	// m[3] is the rest of the package path
	if len(m) != 4 {
		return "", "", fmt.Errorf("bad dir %s", dir)
	}
	if !semver.IsValid(m[2]) {
		return "", "", fmt.Errorf("bad semantic version %s", m[2])
	}
	// ToSlash is required to convert Windows file paths
	// into Go package import paths.
	return filepath.ToSlash(m[1] + m[3]), m[2], nil
}

// findDirs returns an unordered list of relevant package directories,
// relative to the specified module cache root. The result includes only
// module dirs whose mtime is within (start, end).
func findDirs(root string, start, end time.Time) []string {
	var (
		resMu sync.Mutex
		res   []string
	)

	addDir := func(root gopathwalk.Root, dir string) {
		// TODO(pjw): do we need to check times?
		resMu.Lock()
		defer resMu.Unlock()
		res = append(res, relative(root.Path, dir))
	}

	skipDir := func(_ gopathwalk.Root, dir string) bool {
		// The cache directory is already ignored in gopathwalk.
		if filepath.Base(dir) == "internal" {
			return true
		}

		// Skip toolchains.
		if strings.Contains(dir, "toolchain@") {
			return true
		}

		// Don't look inside @ directories that are too old/new.
		if strings.Contains(filepath.Base(dir), "@") {
			st, err := os.Stat(dir)
			if err != nil {
				log.Printf("can't stat dir %s %v", dir, err)
				return true
			}
			mtime := st.ModTime()
			return mtime.Before(start) || mtime.After(end)
		}

		return false
	}

	// TODO(adonovan): parallelize this. Even with a hot buffer cache,
	//   find $(go env GOMODCACHE) -type d
	// can easily take up a minute.
	roots := []gopathwalk.Root{{Path: root, Type: gopathwalk.RootModuleCache}}
	gopathwalk.WalkSkip(roots, addDir, skipDir, gopathwalk.Options{
		ModulesEnabled: true,
		Concurrency:    1, // TODO(pjw): adjust concurrency
		// Logf: log.Printf,
	})

	return res
}


================================================
FILE: internal/modindex/export_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex

// backdoors for tests

var Uniquify = uniquify

// Create always creates a new index for the
// specified Go module cache directory.
// On success it returns the current index.
func Create(gomodcache string) (*Index, error) {
	return update(gomodcache, nil)
}


================================================
FILE: internal/modindex/gomodindex/cmd.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// A command for building and maintaining the module cache
// a.out <flags> <command> <args>
// The commands are:
// 'update', which attempts to update an existing index,
// 'query', which looks up things in the index.
// 'clean', which remove obsolete index files.
// If the command is invoked with no arguments, it defaults to 'update'.
package main

import (
	"bytes"
	"flag"
	"fmt"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"

	"golang.org/x/tools/internal/modindex"
)

var verbose = flag.Int("v", 0, "how much information to print")

type cmd struct {
	name string
	f    func(string)
	doc  string
}

var cmds = []cmd{
	{"update", update, "if there is an existing index of GOMODCACHE, update it. Otherwise create one."},
	{"clean", clean, "removed unreferenced indexes more than an hour old"},
	{"query", query, "not yet implemented"},
}

func goEnv(s string) string {
	out, err := exec.Command("go", "env", s).Output()
	if err != nil {
		return ""
	}
	out = bytes.TrimSpace(out)
	return string(out)
}

func main() {
	flag.Parse()
	log.SetFlags(log.Lshortfile)
	gomodcache := goEnv("GOMODCACHE")
	if gomodcache == "" {
		log.Fatal("can't find GOMODCACHE")
	}
	if flag.NArg() == 0 {
		update(gomodcache)
		return
	}
	for _, c := range cmds {
		if flag.Arg(0) == c.name {
			c.f(gomodcache)
			return
		}
	}
	flag.Usage()
}

func init() {
	var sb strings.Builder
	fmt.Fprintf(&sb, "usage:\n")
	for _, c := range cmds {
		fmt.Fprintf(&sb, "'%s': %s\n", c.name, c.doc)
	}
	msg := sb.String()
	flag.Usage = func() {
		fmt.Fprint(os.Stderr, msg)
	}
}

func update(dir string) {
	if _, err := modindex.Update(dir); err != nil {
		log.Print(err)
	}
}

func query(dir string) {
	panic("implement")
}

func clean(_ string) {
	des := modindex.IndexDir
	// look at the files starting with 'index'
	// the current ones of each version are pointed to by
	// index-name-%d files. Any others more than an hour old
	// are deleted.
	dis, err := os.ReadDir(des)
	if err != nil {
		log.Fatal(err)
	}
	cutoff := time.Now().Add(-time.Hour)
	var inames []string               // older files named index*
	curnames := make(map[string]bool) // current versions of index (different CurrentVersion)
	for _, de := range dis {
		if !strings.HasPrefix(de.Name(), "index") {
			continue
		}
		if strings.HasPrefix(de.Name(), "index-name-") {
			buf, err := os.ReadFile(filepath.Join(des, de.Name()))
			if err != nil {
				log.Print(err)
				continue
			}
			curnames[string(buf)] = true
			if *verbose > 1 {
				log.Printf("latest index is %s", string(buf))
			}
		}
		info, err := de.Info()
		if err != nil {
			log.Print(err)
			continue
		}
		if info.ModTime().Before(cutoff) && !strings.HasPrefix(de.Name(), "index-name-") {
			// add to the list of files to be removed. index-name-%d files are never removed
			inames = append(inames, de.Name())
			if *verbose > 0 {
				log.Printf("%s:%s", de.Name(), cutoff.Sub(info.ModTime()))
			}
		}
	}
	for _, nm := range inames {
		if curnames[nm] {
			continue
		}
		err := os.Remove(filepath.Join(des, nm))
		if err != nil && *verbose > 0 {
			log.Printf("%s not removed (%v)", nm, err)
		}
	}
}


================================================
FILE: internal/modindex/index.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex

import (
	"bufio"
	"crypto/sha256"
	"encoding/csv"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
	"time"
)

/*
The on-disk index ("payload") is a text file.
The first 3 lines are header information containing CurrentVersion,
the value of GOMODCACHE, and the validity date of the index.
(This is when the code started building the index.)
Following the header are sections of lines, one section for each
import path. These sections are sorted by package name.
The first line of each section, marked by a leading :, contains
the package name, the import path, the name of the directory relative
to GOMODCACHE, and its semantic version.
The rest of each section consists of one line per exported symbol.
The lines are sorted by the symbol's name and contain the name,
an indication of its lexical type (C, T, V, F), and if it is the
name of a function, information about the signature.

The fields in the section header lines are separated by commas, and
in the unlikely event this would be confusing, the csv package is used
to write (and read) them.

In the lines containing exported names, C=const, V=var, T=type, F=func.
If it is a func, the next field is the number of returned values,
followed by pairs consisting of formal parameter names and types.
All these fields are separated by spaces. Any spaces in a type
(e.g., chan struct{}) are replaced by $s on the disk. The $s are
turned back into spaces when read.

Here is an index header (the comments are not part of the index):
0                                      // version (of the index format)
/usr/local/google/home/pjw/go/pkg/mod  // GOMODCACHE
2024-09-11 18:55:09                    // validity date of the index

Here is an index section:
:yaml,gopkg.in/yaml.v1,gopkg.in/yaml.v1@v1.0.0-20140924161607-9f9df34309c0,v1.0.0-20140924161607-9f9df34309c0
Getter T
Marshal F 2 in interface{}
Setter T
Unmarshal F 1 in []byte out interface{}

The package name is yaml, the import path is gopkg.in/yaml.v1.
Getter and Setter are types, and Marshal and Unmarshal are functions.
The latter returns one value and has two arguments, 'in' and 'out'
whose types are []byte and interface{}.
*/

// CurrentVersion tells readers about the format of the index.
const CurrentVersion int = 0

// Index is returned by [Read].
type Index struct {
	Version    int
	GOMODCACHE string    // absolute path of Go module cache dir
	ValidAt    time.Time // moment at which the index was up to date
	Entries    []Entry
}

func (ix *Index) String() string {
	return fmt.Sprintf("Index(%s v%d has %d entries at %v)",
		ix.GOMODCACHE, ix.Version, len(ix.Entries), ix.ValidAt)
}

// An Entry contains information for an import path.
type Entry struct {
	Dir        string // package directory relative to GOMODCACHE; uses OS path separator
	ImportPath string
	PkgName    string
	Version    string
	Names      []string // exported names and information
}

// IndexDir is where the module index is stored.
// Each logical index entry consists of a pair of files:
//
//   - the "payload" (index-VERSION-XXX), whose name is
//     randomized, holds the actual index; and
//   - the "link" (index-name-VERSION-HASH),
//     whose name is predictable, contains the
//     name of the payload file.
//
// Since the link file is small (<512B),
// reads and writes to it may be assumed atomic.
var IndexDir string = func() string {
	var dir string
	if testing.Testing() {
		dir = os.TempDir()
	} else {
		var err error
		dir, err = os.UserCacheDir()
		// shouldn't happen, but TempDir is better than
		// creating ./goimports
		if err != nil {
			dir = os.TempDir()
		}
	}
	dir = filepath.Join(dir, "goimports")
	if err := os.MkdirAll(dir, 0777); err != nil {
		dir = "" // #75505, people complain about the error message
	}
	return dir
}()

// Read reads the latest version of the on-disk index
// for the specified Go module cache directory.
// If there is no index, it returns a nil Index and an fs.ErrNotExist error.
func Read(gomodcache string) (*Index, error) {
	gomodcache, err := filepath.Abs(gomodcache)
	if err != nil {
		return nil, err
	}
	if IndexDir == "" {
		return nil, os.ErrNotExist
	}

	// Read the "link" file for the specified gomodcache directory.
	// It names the payload file.
	content, err := os.ReadFile(filepath.Join(IndexDir, linkFileBasename(gomodcache)))
	if err != nil {
		return nil, err
	}
	payloadFile := filepath.Join(IndexDir, string(content))

	// Read the index out of the payload file.
	f, err := os.Open(payloadFile)
	if err != nil {
		return nil, err
	}
	defer f.Close()
	return readIndexFrom(gomodcache, bufio.NewReader(f))
}

func readIndexFrom(gomodcache string, r io.Reader) (*Index, error) {
	scan := bufio.NewScanner(r)

	// version
	if !scan.Scan() {
		return nil, fmt.Errorf("unexpected scan error: %v", scan.Err())
	}
	version, err := strconv.Atoi(scan.Text())
	if err != nil {
		return nil, err
	}
	if version != CurrentVersion {
		return nil, fmt.Errorf("got version %d, expected %d", version, CurrentVersion)
	}

	// gomodcache
	if !scan.Scan() {
		return nil, fmt.Errorf("scanner error reading module cache dir: %v", scan.Err())
	}
	// TODO(pjw): need to check that this is the expected cache dir
	// so the tag should be passed in to this function
	if dir := string(scan.Text()); dir != gomodcache {
		return nil, fmt.Errorf("index file GOMODCACHE mismatch: got %q, want %q", dir, gomodcache)
	}

	// changed
	if !scan.Scan() {
		return nil, fmt.Errorf("scanner error reading index creation time: %v", scan.Err())
	}
	changed, err := time.ParseInLocation(time.DateTime, scan.Text(), time.Local)
	if err != nil {
		return nil, err
	}

	// entries
	var (
		curEntry *Entry
		entries  []Entry
	)
	for scan.Scan() {
		v := scan.Text()
		if v[0] == ':' {
			if curEntry != nil {
				entries = append(entries, *curEntry)
			}
			// as directories may contain commas and quotes, they need to be read as csv.
			rdr := strings.NewReader(v[1:])
			cs := csv.NewReader(rdr)
			flds, err := cs.Read()
			if err != nil {
				return nil, err
			}
			if len(flds) != 4 {
				return nil, fmt.Errorf("header contains %d fields, not 4: %q", len(v), v)
			}
			curEntry = &Entry{
				PkgName:    flds[0],
				ImportPath: flds[1],
				Dir:        relative(gomodcache, flds[2]),
				Version:    flds[3],
			}
			continue
		}
		curEntry.Names = append(curEntry.Names, v)
	}
	if err := scan.Err(); err != nil {
		return nil, fmt.Errorf("scanner failed while reading modindex entry: %v", err)
	}
	if curEntry != nil {
		entries = append(entries, *curEntry)
	}

	return &Index{
		Version:    version,
		GOMODCACHE: gomodcache,
		ValidAt:    changed,
		Entries:    entries,
	}, nil
}

// write writes the index file and updates the index directory to refer to it.
func write(gomodcache string, ix *Index) error {
	if IndexDir == "" {
		return os.ErrNotExist
	}
	// Write the index into a payload file with a fresh name.
	f, err := os.CreateTemp(IndexDir, fmt.Sprintf("index-%d-*", CurrentVersion))
	if err != nil {
		return err // e.g. disk full, or index dir deleted
	}
	if err := writeIndexToFile(ix, bufio.NewWriter(f)); err != nil {
		_ = f.Close() // ignore error
		return err
	}
	if err := f.Close(); err != nil {
		return err
	}

	// Write the name of the payload file into a link file.
	indexDirFile := filepath.Join(IndexDir, linkFileBasename(gomodcache))
	content := []byte(filepath.Base(f.Name()))
	return os.WriteFile(indexDirFile, content, 0666)
}

func writeIndexToFile(x *Index, w *bufio.Writer) error {
	fmt.Fprintf(w, "%d\n", x.Version)
	fmt.Fprintf(w, "%s\n", x.GOMODCACHE)
	tm := x.ValidAt.Truncate(time.Second) // round the time down
	fmt.Fprintf(w, "%s\n", tm.Format(time.DateTime))
	for _, e := range x.Entries {
		if e.ImportPath == "" {
			continue // shouldn't happen
		}
		// PJW: maybe always write these headers as csv?
		if strings.ContainsAny(string(e.Dir), ",\"") {
			cw := csv.NewWriter(w)
			cw.Write([]string{":" + e.PkgName, e.ImportPath, string(e.Dir), e.Version})
			cw.Flush()
		} else {
			fmt.Fprintf(w, ":%s,%s,%s,%s\n", e.PkgName, e.ImportPath, e.Dir, e.Version)
		}
		for _, x := range e.Names {
			fmt.Fprintf(w, "%s\n", x)
		}
	}
	return w.Flush()
}

// linkFileBasename returns the base name of the link file in the
// index directory that holds the name of the payload file for the
// specified (absolute) Go module cache dir.
func linkFileBasename(gomodcache string) string {
	// Note: coupled to logic in ./gomodindex/cmd.go. TODO: factor.
	h := sha256.Sum256([]byte(gomodcache)) // collision-resistant hash
	return fmt.Sprintf("index-name-%d-%032x", CurrentVersion, h)
}

func relative(base, file string) string {
	if rel, err := filepath.Rel(base, file); err == nil {
		return rel
	}
	return file
}


================================================
FILE: internal/modindex/lookup.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex

import (
	"slices"
	"strconv"
	"strings"

	"golang.org/x/mod/module"
)

type Candidate struct {
	PkgName    string
	Name       string
	Dir        string
	ImportPath string
	Type       LexType
	Deprecated bool
	// information for Funcs
	Results int16   // how many results
	Sig     []Field // arg names and types
}

type Field struct {
	Arg, Type string
}

type LexType int8

const (
	Const LexType = iota
	Var
	Type
	Func
)

// LookupAll only returns those Candidates whose import path
// finds all the names.
func (ix *Index) LookupAll(pkgName string, names ...string) map[string][]Candidate {
	// this can be made faster when benchmarks show that it needs to be
	names = uniquify(names)
	byImpPath := make(map[string][]Candidate)
	for _, nm := range names {
		cands := ix.Lookup(pkgName, nm, false)
		for _, c := range cands {
			byImpPath[c.ImportPath] = append(byImpPath[c.ImportPath], c)
		}
	}
	for k, v := range byImpPath {
		if len(v) != len(names) {
			delete(byImpPath, k)
		}
	}
	return byImpPath
}

// remove duplicates
func uniquify(in []string) []string {
	if len(in) == 0 {
		return in
	}
	in = slices.Clone(in)
	slices.Sort(in)
	return slices.Compact(in)
}

// Lookup finds all the symbols in the index with the given PkgName and name.
// If prefix is true, it finds all of these with name as a prefix.
func (ix *Index) Lookup(pkgName, name string, prefix bool) []Candidate {
	loc, ok := slices.BinarySearchFunc(ix.Entries, pkgName, func(e Entry, pkg string) int {
		return strings.Compare(e.PkgName, pkgName)
	})
	if !ok {
		return nil // didn't find the package
	}
	var ans []Candidate
	// loc is the first entry for this package name, but there may be several
	for i := loc; i < len(ix.Entries); i++ {
		e := ix.Entries[i]
		if e.PkgName != pkgName {
			break // end of sorted package names
		}
		nloc, ok := slices.BinarySearchFunc(e.Names, name, func(s string, name string) int {
			if strings.HasPrefix(s, name) {
				return 0
			}
			if s < name {
				return -1
			}
			return 1
		})
		if !ok {
			continue // didn't find the name, nor any symbols with name as a prefix
		}
		for j := nloc; j < len(e.Names); j++ {
			nstr := e.Names[j]
			// benchmarks show this makes a difference when there are a lot of Possibilities
			flds := fastSplit(nstr)
			if !(flds[0] == name || prefix && strings.HasPrefix(flds[0], name)) {
				// past range of matching Names
				break
			}
			if len(flds) < 2 {
				continue // should never happen
			}
			impPath, err := module.UnescapePath(e.ImportPath)
			if err != nil {
				continue
			}
			px := Candidate{
				PkgName:    pkgName,
				Name:       flds[0],
				Dir:        string(e.Dir),
				ImportPath: impPath,
				Type:       asLexType(flds[1][0]),
				Deprecated: len(flds[1]) > 1 && flds[1][1] == 'D',
			}
			if px.Type == Func {
				n, err := strconv.Atoi(flds[2])
				if err != nil {
					continue // should never happen
				}
				px.Results = int16(n)
				if len(flds) >= 4 {
					sig := strings.Split(flds[3], " ")
					for i := range sig {
						// $ cannot otherwise occur. removing the spaces
						// almost works, but for chan struct{}, e.g.
						sig[i] = strings.Replace(sig[i], "$", " ", -1)
					}
					px.Sig = toFields(sig)
				}
			}
			ans = append(ans, px)
		}
	}
	return ans
}

func toFields(sig []string) []Field {
	ans := make([]Field, len(sig)/2)
	for i := range ans {
		ans[i] = Field{Arg: sig[2*i], Type: sig[2*i+1]}
	}
	return ans
}

// benchmarks show this is measurably better than strings.Split
// split into first 4 fields separated by single space
func fastSplit(x string) []string {
	ans := make([]string, 0, 4)
	nxt := 0
	start := 0
	for i := 0; i < len(x); i++ {
		if x[i] != ' ' {
			continue
		}
		ans = append(ans, x[start:i])
		nxt++
		start = i + 1
		if nxt >= 3 {
			break
		}
	}
	ans = append(ans, x[start:])
	return ans
}

func asLexType(c byte) LexType {
	switch c {
	case 'C':
		return Const
	case 'V':
		return Var
	case 'T':
		return Type
	case 'F':
		return Func
	}
	return -1
}


================================================
FILE: internal/modindex/lookup_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex_test

import (
	"fmt"
	"log"
	"os"
	"path/filepath"
	"strings"
	"testing"

	. "golang.org/x/tools/internal/modindex"
)

type tdata struct {
	fname string
	pkg   string
	items []titem
}

type titem struct {
	code   string
	result result
}

var thedata = tdata{
	fname: "cloud.google.com/go/!longrunning@v0.4.1/foo.go",
	pkg:   "foo",
	items: []titem{
		// these need to be in alphabetical order
		{"func Foo() {}", result{"Foo", Func, false, 0, nil}},
		{"const FooC = 23", result{"FooC", Const, false, 0, nil}},
		{"func FooF(int, float) error {return nil}", result{"FooF", Func, false, 1,
			[]Field{{"_", "int"}, {"_", "float"}}}},
		{"type FooT struct{}", result{"FooT", Type, false, 0, nil}},
		{"var FooV int", result{"FooV", Var, false, 0, nil}},
		{"func Goo() {}", result{"Goo", Func, false, 0, nil}},
		{"/*Deprecated: too weird\n*/\n// Another Goo\nvar GooVV int", result{"GooVV", Var, true, 0, nil}},
		{"func Ⱋoox(x int) {}", result{"Ⱋoox", Func, false, 0, []Field{{"x", "int"}}}},
	},
}

type result struct {
	name       string
	typ        LexType
	deprecated bool
	result     int
	sig        []Field
}

func okresult(r result, p Candidate) bool {
	if r.name != p.Name || r.typ != p.Type || r.result != int(p.Results) {
		return false
	}
	if r.deprecated != p.Deprecated {
		return false
	}
	if len(r.sig) != len(p.Sig) {
		return false
	}
	for i := 0; i < len(r.sig); i++ {
		if r.sig[i] != p.Sig[i] {
			return false
		}
	}
	return true
}

func TestLookup(t *testing.T) {
	dir := testModCache(t)
	wrtData(t, dir, thedata)
	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	ix, err := Read(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(ix.Entries) != 1 {
		t.Fatalf("got %d Entries, expected 1", len(ix.Entries))
	}
	// get all the symbols
	p := ix.Lookup("foo", "", true)
	if len(p) > 0 && !strings.Contains(p[0].ImportPath, "Longrunning") {
		t.Errorf("Failed to convert escaped path: %s", p[0].ImportPath)
	}
	if len(p) != len(thedata.items) {
		t.Errorf("got %d possibilities for pkg foo, expected %d", len(p), len(thedata.items))
	}
	for i, r := range thedata.items {
		if !okresult(r.result, p[i]) {
			t.Errorf("got %#v, expected %#v", p[i], r.result)
		}
	}
	// look for the Foo... and check that each is a Foo...
	p = ix.Lookup("foo", "Foo", true)
	if len(p) != 5 {
		t.Errorf("got %d possibilities for foo.Foo*, expected 5", len(p))
	}
	for _, r := range p {
		if !strings.HasPrefix(r.Name, "Foo") {
			t.Errorf("got %s, expected Foo...", r.Name)
		}
	}
	// fail to find something
	p = ix.Lookup("foo", "FooVal", false)
	if len(p) != 0 {
		t.Errorf("got %d possibilities for foo.FooVal, expected 0", len(p))
	}
	// find an exact match
	p = ix.Lookup("foo", "Foo", false)
	if len(p) != 1 {
		t.Errorf("got %d possibilities for foo.Foo, expected 1", len(p))
	}
	// "Foo" is the first test datum
	if !okresult(thedata.items[0].result, p[0]) {
		t.Errorf("got %#v, expected %#v", p[0], thedata.items[0].result)
	}
}

func wrtData(t *testing.T, dir string, data tdata) {
	t.Helper()
	locname := filepath.FromSlash(data.fname)
	if err := os.MkdirAll(filepath.Join(dir, filepath.Dir(locname)), 0755); err != nil {
		t.Fatal(err)
	}
	fd, err := os.Create(filepath.Join(dir, locname))
	if err != nil {
		t.Fatal(err)
	}
	defer fd.Close()
	fmt.Fprintf(fd, "package %s\n", data.pkg)
	for _, item := range data.items {
		fd.WriteString(item.code + "\n")
	}
}

func TestLookupAll(t *testing.T) {
	log.SetFlags(log.Lshortfile)
	dir := testModCache(t)
	wrtModule := func(mod string, nms ...string) {
		dname := filepath.Join(dir, mod)
		if err := os.MkdirAll(dname, 0755); err != nil {
			t.Fatal(err)
		}
		fname := filepath.Join(dname, "foo.go")
		fd, err := os.Create(fname)
		if err != nil {
			t.Fatal(err)
		}
		defer fd.Close()
		if _, err := fmt.Fprintf(fd, "package foo\n"); err != nil {
			t.Fatal(err)
		}
		for _, nm := range nms {
			fmt.Fprintf(fd, "func %s() {}\n", nm)
		}
	}
	wrtModule("a.com/go/x4@v1.1.1", "A", "B", "C", "D")
	wrtModule("b.com/go/x3@v1.2.1", "A", "B", "C")
	wrtModule("c.com/go/x5@v1.3.1", "A", "B", "C", "D", "E")

	if _, err := Create(dir); err != nil {
		t.Fatal(err)
	}
	ix, err := Read(dir)
	if err != nil {
		t.Fatal(err)
	}
	cands := ix.Lookup("foo", "A", false)
	if len(cands) != 3 {
		t.Errorf("got %d candidates for A, expected 3", len(cands))
	}
	got := ix.LookupAll("foo", "A", "B", "C", "D")
	if len(got) != 2 {
		t.Errorf("got %d candidates for A,B,C,D, expected 2", len(got))
	}
	got = ix.LookupAll("foo", []string{"A", "B", "C", "D", "E"}...)
	if len(got) != 1 {
		t.Errorf("got %d candidates for A,B,C,D,E, expected 1", len(got))
	}
}

func TestUniquify(t *testing.T) {
	var v []string
	for i := 1; i < 4; i++ {
		v = append(v, "A")
		w := Uniquify(v)
		if len(w) != 1 {
			t.Errorf("got %d, expected 1", len(w))
		}
	}
	for i := 1; i < 3; i++ {
		v = append(v, "B", "C")
		w := Uniquify(v)
		if len(w) != 3 {
			t.Errorf("got %d, expected 3", len(w))
		}
	}
}


================================================
FILE: internal/modindex/modindex.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package modindex contains code for building and searching an
// [Index] of the Go module cache.
package modindex

// The directory containing the index, returned by
// [IndexDir], contains a file index-name-<ver> that contains the name
// of the current index. We believe writing that short file is atomic.
// [Read] reads that file to get the file name of the index.
// WriteIndex writes an index with a unique name and then
// writes that name into a new version of index-name-<ver>.
// (<ver> stands for the CurrentVersion of the index format.)

import (
	"maps"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"time"

	"golang.org/x/mod/semver"
)

// Update updates the index for the specified Go
// module cache directory, creating it as needed.
// On success it returns the current index.
func Update(gomodcache string) (*Index, error) {
	prev, err := Read(gomodcache)
	if err != nil {
		if !os.IsNotExist(err) {
			return nil, err
		}
		prev = nil
	}
	return update(gomodcache, prev)
}

// update builds, writes, and returns the current index.
//
// If old is nil, the new index is built from all of GOMODCACHE;
// otherwise it is built from the old index plus cache updates
// since the previous index's time.
func update(gomodcache string, old *Index) (*Index, error) {
	gomodcache, err := filepath.Abs(gomodcache)
	if err != nil {
		return nil, err
	}
	new, changed, err := build(gomodcache, old)
	if err != nil {
		return nil, err
	}
	if old == nil || changed {
		if err := write(gomodcache, new); err != nil {
			return nil, err
		}
	}
	return new, nil
}

// build returns a new index for the specified Go module cache (an
// absolute path).
//
// If an old index is provided, only directories more recent than it
// that it are scanned; older directories are provided by the old
// Index.
//
// The boolean result indicates whether new entries were found.
func build(gomodcache string, old *Index) (*Index, bool, error) {
	// Set the time window.
	var start time.Time // = dawn of time
	if old != nil {
		start = old.ValidAt
	}
	now := time.Now()
	end := now.Add(24 * time.Hour) // safely in the future

	// Enumerate GOMODCACHE package directories.
	// Choose the best (latest) package for each import path.
	pkgDirs := findDirs(gomodcache, start, end)
	dirByPath, err := bestDirByImportPath(pkgDirs)
	if err != nil {
		return nil, false, err
	}

	// For each import path it might occur only in
	// dirByPath, only in old, or in both.
	// If both, use the semantically later one.
	var entries []Entry
	if old != nil {
		for _, entry := range old.Entries {
			dir, ok := dirByPath[entry.ImportPath]
			if !ok || semver.Compare(dir.version, entry.Version) <= 0 {
				// New dir is missing or not more recent; use old entry.
				entries = append(entries, entry)
				delete(dirByPath, entry.ImportPath)
			}
		}
	}

	// Extract symbol information for all the new directories.
	newEntries := extractSymbols(gomodcache, maps.Values(dirByPath))
	entries = append(entries, newEntries...)
	slices.SortFunc(entries, func(x, y Entry) int {
		if n := strings.Compare(x.PkgName, y.PkgName); n != 0 {
			return n
		}
		return strings.Compare(x.ImportPath, y.ImportPath)
	})

	return &Index{
		GOMODCACHE: gomodcache,
		ValidAt:    now, // time before the directories were scanned
		Entries:    entries,
	}, len(newEntries) > 0, nil
}


================================================
FILE: internal/modindex/symbols.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package modindex

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"iter"
	"os"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"sync"

	"golang.org/x/sync/errgroup"
)

// The name of a symbol contains information about the symbol:
// <name> T for types, TD if the type is deprecated
// <name> C for consts, CD if the const is deprecated
// <name> V for vars, VD if the var is deprecated
// and for funcs: <name> F <num of return values> (<arg-name> <arg-type>)*
// any spaces in <arg-type> are replaced by $s so that the fields
// of the name are space separated. F is replaced by FD if the func
// is deprecated.
type symbol struct {
	pkg  string // name of the symbols's package
	name string // declared name
	kind string // T, C, V, or F, followed by D if deprecated
	sig  string // signature information, for F
}

// extractSymbols returns a (new, unordered) array of Entries, one for
// each provided package directory, describing its exported symbols.
func extractSymbols(cwd string, dirs iter.Seq[directory]) []Entry {
	var (
		mu      sync.Mutex
		entries []Entry
	)

	var g errgroup.Group
	g.SetLimit(max(2, runtime.GOMAXPROCS(0)/2))
	for dir := range dirs {
		g.Go(func() error {
			thedir := filepath.Join(cwd, string(dir.path))
			mode := parser.SkipObjectResolution | parser.ParseComments

			// Parse all Go files in dir and extract symbols.
			dirents, err := os.ReadDir(thedir)
			if err != nil {
				return nil // log this someday?
			}
			var syms []symbol
			for _, dirent := range dirents {
				if !strings.HasSuffix(dirent.Name(), ".go") ||
					strings.HasSuffix(dirent.Name(), "_test.go") {
					continue
				}
				fname := filepath.Join(thedir, dirent.Name())
				tr, err := parser.ParseFile(token.NewFileSet(), fname, nil, mode)
				if err != nil {
					continue // ignore errors, someday log them?
				}
				syms = append(syms, getFileExports(tr)...)
			}

			// Create an entry for the package.
			pkg, names := processSyms(syms)
			if pkg != "" {
				mu.Lock()
				defer mu.Unlock()
				entries = append(entries, Entry{
					PkgName:    pkg,
					Dir:        dir.path,
					ImportPath: dir.importPath,
					Version:    dir.version,
					Names:      names,
				})
			}

			return nil
		})
	}
	g.Wait() // ignore error

	return entries
}

func getFileExports(f *ast.File) []symbol {
	pkg := f.Name.Name
	if pkg == "main" || pkg == "" {
		return nil
	}
	var ans []symbol
	// should we look for //go:build ignore?
	for _, decl := range f.Decls {
		switch decl := decl.(type) {
		case *ast.FuncDecl:
			if decl.Recv != nil {
				// ignore methods, as we are completing package selections
				continue
			}
			name := decl.Name.Name
			dtype := decl.Type
			// not looking at dtype.TypeParams. That is, treating
			// generic functions just like non-generic ones.
			sig := dtype.Params
			kind := "F"
			if isDeprecated(decl.Doc) {
				kind += "D"
			}
			result := []string{fmt.Sprintf("%d", dtype.Results.NumFields())}
			for _, x := range sig.List {
				// This code creates a string representing the type.
				// TODO(pjw): it may be fragile:
				// 1. x.Type could be nil, perhaps in ill-formed code
				// 2. ExprString might someday change incompatibly to
				//    include struct tags, which can be arbitrary strings
				if x.Type == nil {
					// Can this happen without a parse error? (Files with parse
					// errors are ignored in getSymbols)
					continue // maybe report this someday
				}
				tp := types.ExprString(x.Type)
				if len(tp) == 0 {
					// Can this happen?
					continue // maybe report this someday
				}
				// This is only safe if ExprString never returns anything with a $
				// The only place a $ can occur seems to be in a struct tag, which
				// can be an arbitrary string literal, and ExprString does not presently
				// print struct tags. So for this to happen the type of a formal parameter
				// has to be a explicit struct, e.g. foo(x struct{a int "$"}) and ExprString
				// would have to show the struct tag. Even testing for this case seems
				// a waste of effort, but let's remember the possibility
				if strings.Contains(tp, "$") {
					continue
				}
				tp = strings.Replace(tp, " ", "$", -1)
				if len(x.Names) == 0 {
					result = append(result, "_")
					result = append(result, tp)
				} else {
					for _, y := range x.Names {
						result = append(result, y.Name)
						result = append(result, tp)
					}
				}
			}
			sigs := strings.Join(result, " ")
			if s := newsym(pkg, name, kind, sigs); s != nil {
				ans = append(ans, *s)
			}
		case *ast.GenDecl:
			depr := isDeprecated(decl.Doc)
			switch decl.Tok {
			case token.CONST, token.VAR:
				tp := "V"
				if decl.Tok == token.CONST {
					tp = "C"
				}
				if depr {
					tp += "D"
				}
				for _, sp := range decl.Specs {
					for _, x := range sp.(*ast.ValueSpec).Names {
						if s := newsym(pkg, x.Name, tp, ""); s != nil {
							ans = append(ans, *s)
						}
					}
				}
			case token.TYPE:
				tp := "T"
				if depr {
					tp += "D"
				}
				for _, sp := range decl.Specs {
					if s := newsym(pkg, sp.(*ast.TypeSpec).Name.Name, tp, ""); s != nil {
						ans = append(ans, *s)
					}
				}
			}
		}
	}
	return ans
}

func newsym(pkg, name, kind, sig string) *symbol {
	if len(name) == 0 || !ast.IsExported(name) {
		return nil
	}
	sym := symbol{pkg: pkg, name: name, kind: kind, sig: sig}
	return &sym
}

func isDeprecated(doc *ast.CommentGroup) bool {
	if doc == nil {
		return false
	}
	// go.dev/wiki/Deprecated Paragraph starting 'Deprecated:'
	// This code fails for /* Deprecated: */, but it's the code from
	// gopls/internal/analysis/deprecated
	for line := range strings.SplitSeq(doc.Text(), "\n\n") {
		if strings.HasPrefix(line, "Deprecated:") {
			return true
		}
	}
	return false
}

// return the package name and the value for the symbols.
// if there are multiple packages, choose one arbitrarily
// the returned slice is sorted lexicographically
func processSyms(syms []symbol) (string, []string) {
	if len(syms) == 0 {
		return "", nil
	}
	slices.SortFunc(syms, func(l, r symbol) int {
		return strings.Compare(l.name, r.name)
	})
	pkg := syms[0].pkg
	var names []string
	for _, s := range syms {
		if s.pkg != pkg {
			// Symbols came from two files in same dir
			// with different package declarations.
			continue
		}
		var nx string
		if s.sig != "" {
			nx = fmt.Sprintf("%s %s %s", s.name, s.kind, s.sig)
		} else {
			nx = fmt.Sprintf("%s %s", s.name, s.kind)
		}
		names = append(names, nx)
	}
	return pkg, names
}


================================================
FILE: internal/moreiters/iters.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package moreiters

import "iter"

// First returns the first value of seq and true.
// If seq is empty, it returns the zero value of T and false.
func First[T any](seq iter.Seq[T]) (z T, ok bool) {
	for t := range seq {
		return t, true
	}
	return z, false
}

// Contains reports whether x is an element of the sequence seq.
func Contains[T comparable](seq iter.Seq[T], x T) bool {
	for cand := range seq {
		if cand == x {
			return true
		}
	}
	return false
}

// Every reports whether every pred(t) for t in seq returns true,
// stopping at the first false element.
func Every[T any](seq iter.Seq[T], pred func(T) bool) bool {
	for t := range seq {
		if !pred(t) {
			return false
		}
	}
	return true
}

// Any reports whether any pred(t) for t in seq returns true.
func Any[T any](seq iter.Seq[T], pred func(T) bool) bool {
	for t := range seq {
		if pred(t) {
			return true
		}
	}
	return false
}

// Len returns the number of elements in the sequence (by iterating).
func Len[T any](seq iter.Seq[T]) (n int) {
	for range seq {
		n++
	}
	return
}


================================================
FILE: internal/packagepath/packagepath.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package packagepath provides metadata operations on package path
// strings.
package packagepath

// (This package should not depend on go/ast.)
import "strings"

// CanImport reports whether one package is allowed to import another.
//
// TODO(adonovan): allow customization of the accessibility relation
// (e.g. for Bazel).
func CanImport(from, to string) bool {
	// TODO(adonovan): better segment hygiene.
	if to == "internal" || strings.HasPrefix(to, "internal/") {
		// Special case: only std packages may import internal/...
		// We can't reliably know whether we're in std, so we
		// use a heuristic on the first segment.
		first, _, _ := strings.Cut(from, "/")
		if strings.Contains(first, ".") {
			return false // example.com/foo ∉ std
		}
		if first == "testdata" {
			return false // testdata/foo ∉ std
		}
	}
	if strings.HasSuffix(to, "/internal") {
		return strings.HasPrefix(from, to[:len(to)-len("/internal")])
	}
	if i := strings.LastIndex(to, "/internal/"); i >= 0 {
		return strings.HasPrefix(from, to[:i])
	}
	return true
}

// IsStdPackage reports whether the specified package path belongs to a
// package in the standard library (including internal dependencies).
func IsStdPackage(path string) bool {
	// A standard package has no dot in its first segment.
	// (It may yet have a dot, e.g. "vendor/golang.org/x/foo".)
	slash := strings.IndexByte(path, '/')
	if slash < 0 {
		slash = len(path)
	}
	return !strings.Contains(path[:slash], ".") && path != "testdata"
}


================================================
FILE: internal/packagepath/packagepath_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagepath_test

import (
	"testing"

	. "golang.org/x/tools/internal/packagepath"
)

func TestCanImport(t *testing.T) {
	for _, tt := range []struct {
		from string
		to   string
		want bool
	}{
		{"fmt", "internal", true},
		{"fmt", "internal/foo", true},
		{"fmt", "fmt/internal/foo", true},
		{"fmt", "cmd/internal/archive", false},
		{"a.com/b", "internal", false},
		{"a.com/b", "xinternal", true},
		{"a.com/b", "internal/foo", false},
		{"a.com/b", "xinternal/foo", true},
		{"a.com/b", "a.com/internal", true},
		{"a.com/b", "a.com/b/internal", true},
		{"a.com/b", "a.com/b/internal/foo", true},
		{"a.com/b", "a.com/c/internal", false},
		{"a.com/b", "a.com/c/xinternal", true},
		{"a.com/b", "a.com/c/internal/foo", false},
		{"a.com/b", "a.com/c/xinternal/foo", true},
	} {
		got := CanImport(tt.from, tt.to)
		if got != tt.want {
			t.Errorf("CanImport(%q, %q) = %v, want %v", tt.from, tt.to, got, tt.want)
		}
	}
}

func TestIsStdPackage(t *testing.T) {
	testCases := []struct {
		pkgpath string
		isStd   bool
	}{
		{pkgpath: "os", isStd: true},
		{pkgpath: "net/http", isStd: true},
		{pkgpath: "vendor/golang.org/x/net/dns/dnsmessage", isStd: true},
		{pkgpath: "golang.org/x/net/dns/dnsmessage", isStd: false},
		{pkgpath: "testdata", isStd: false},
	}

	for _, tc := range testCases {
		t.Run(tc.pkgpath, func(t *testing.T) {
			got := IsStdPackage(tc.pkgpath)
			if got != tc.isStd {
				t.Fatalf("got %t want %t", got, tc.isStd)
			}
		})
	}
}


================================================
FILE: internal/packagesinternal/packages.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package packagesinternal exposes internal-only fields from go/packages.
package packagesinternal

import "fmt"

var GetDepsErrors = func(p any) []*PackageError { return nil }

type PackageError struct {
	ImportStack []string // shortest path from package named on command line to this one
	Pos         string   // position of error (if present, file:line:col)
	Err         string   // the error itself
}

func (err PackageError) String() string {
	return fmt.Sprintf("%s: %s (import stack: %s)", err.Pos, err.Err, err.ImportStack)
}

var TypecheckCgo int
var DepsErrors int // must be set as a LoadMode to call GetDepsErrors


================================================
FILE: internal/packagestest/expect.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest

import (
	"fmt"
	"go/token"
	"os"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/expect"
)

const (
	markMethod    = "mark"
	eofIdentifier = "EOF"
)

// Expect invokes the supplied methods for all expectation notes found in
// the exported source files.
//
// All exported go source files are parsed to collect the expectation
// notes.
// See the documentation for expect.Parse for how the notes are collected
// and parsed.
//
// The methods are supplied as a map of name to function, and those functions
// will be matched against the expectations by name.
// Notes with no matching function will be skipped, and functions with no
// matching notes will not be invoked.
// If there are no registered markers yet, a special pass will be run first
// which adds any markers declared with @mark(Name, pattern) or @name. These
// call the Mark method to add the marker to the global set.
// You can register the "mark" method to override these in your own call to
// Expect. The bound Mark function is usable directly in your method map, so
//
//	exported.Expect(map[string]interface{}{"mark": exported.Mark})
//
// replicates the built in behavior.
//
// # Method invocation
//
// When invoking a method the expressions in the parameter list need to be
// converted to values to be passed to the method.
// There are a very limited set of types the arguments are allowed to be.
//
//	expect.Note : passed the Note instance being evaluated.
//	string : can be supplied either a string literal or an identifier.
//	int : can only be supplied an integer literal.
//	*regexp.Regexp : can only be supplied a regular expression literal
//	token.Pos : has a file position calculated as described below.
//	token.Position : has a file position calculated as described below.
//	expect.Range: has a start and end position as described below.
//	interface{} : will be passed any value
//
// # Position calculation
//
// There is some extra handling when a parameter is being coerced into a
// token.Pos, token.Position or Range type argument.
//
// If the parameter is an identifier, it will be treated as the name of an
// marker to look up (as if markers were global variables).
//
// If it is a string or regular expression, then it will be passed to
// expect.MatchBefore to look up a match in the line at which it was declared.
//
// It is safe to call this repeatedly with different method sets, but it is
// not safe to call it concurrently.
func (e *Exported) Expect(methods map[string]any) error {
	if err := e.getNotes(); err != nil {
		return err
	}
	if err := e.getMarkers(); err != nil {
		return err
	}
	var err error
	ms := make(map[string]method, len(methods))
	for name, f := range methods {
		mi := method{f: reflect.ValueOf(f)}
		mi.converters = make([]converter, mi.f.Type().NumIn())
		for i := 0; i < len(mi.converters); i++ {
			mi.converters[i], err = e.buildConverter(mi.f.Type().In(i))
			if err != nil {
				return fmt.Errorf("invalid method %v: %v", name, err)
			}
		}
		ms[name] = mi
	}
	for _, n := range e.notes {
		if n.Args == nil {
			// simple identifier form, convert to a call to mark
			n = &expect.Note{
				Pos:  n.Pos,
				Name: markMethod,
				Args: []any{n.Name, n.Name},
			}
		}
		mi, ok := ms[n.Name]
		if !ok {
			continue
		}
		params := make([]reflect.Value, len(mi.converters))
		args := n.Args
		for i, convert := range mi.converters {
			params[i], args, err = convert(n, args)
			if err != nil {
				return fmt.Errorf("%v: %v", e.ExpectFileSet.Position(n.Pos), err)
			}
		}
		if len(args) > 0 {
			return fmt.Errorf("%v: unwanted args got %+v extra", e.ExpectFileSet.Position(n.Pos), args)
		}
		//TODO: catch the error returned from the method
		mi.f.Call(params)
	}
	return nil
}

// Mark adds a new marker to the known set.
func (e *Exported) Mark(name string, r astutil.Range) {
	if e.markers == nil {
		e.markers = make(map[string]astutil.Range)
	}
	e.markers[name] = r
}

func (e *Exported) getNotes() error {
	if e.notes != nil {
		return nil
	}
	notes := []*expect.Note{}
	var dirs []string
	for _, module := range e.written {
		for _, filename := range module {
			dirs = append(dirs, filepath.Dir(filename))
		}
	}
	for filename := range e.Config.Overlay {
		dirs = append(dirs, filepath.Dir(filename))
	}
	pkgs, err := packages.Load(e.Config, dirs...)
	if err != nil {
		return fmt.Errorf("unable to load packages for directories %s: %v", dirs, err)
	}
	seen := make(map[token.Position]struct{})
	for _, pkg := range pkgs {
		for _, filename := range pkg.GoFiles {
			content, err := e.FileContents(filename)
			if err != nil {
				return err
			}
			l, err := expect.Parse(e.ExpectFileSet, filename, content)
			if err != nil {
				return fmt.Errorf("failed to extract expectations: %v", err)
			}
			for _, note := range l {
				pos := e.ExpectFileSet.Position(note.Pos)
				if _, ok := seen[pos]; ok {
					continue
				}
				notes = append(notes, note)
				seen[pos] = struct{}{}
			}
		}
	}
	if _, ok := e.written[e.primary]; !ok {
		e.notes = notes
		return nil
	}
	// Check go.mod markers regardless of mode, we need to do this so that our marker count
	// matches the counts in the summary.txt.golden file for the test directory.
	if gomod, found := e.written[e.primary]["go.mod"]; found {
		// If we are in Modules mode, then we need to check the contents of the go.mod.temp.
		if e.Exporter == Modules {
			gomod += ".temp"
		}
		l, err := goModMarkers(e, gomod)
		if err != nil {
			return fmt.Errorf("failed to extract expectations for go.mod: %v", err)
		}
		notes = append(notes, l...)
	}
	e.notes = notes
	return nil
}

func goModMarkers(e *Exported, gomod string) ([]*expect.Note, error) {
	if _, err := os.Stat(gomod); os.IsNotExist(err) {
		// If there is no go.mod file, we want to be able to continue.
		return nil, nil
	}
	content, err := e.FileContents(gomod)
	if err != nil {
		return nil, err
	}
	if e.Exporter == GOPATH {
		return expect.Parse(e.ExpectFileSet, gomod, content)
	}
	gomod = strings.TrimSuffix(gomod, ".temp")
	// If we are in Modules mode, copy the original contents file back into go.mod
	if err := os.WriteFile(gomod, content, 0644); err != nil {
		return nil, nil
	}
	return expect.Parse(e.ExpectFileSet, gomod, content)
}

func (e *Exported) getMarkers() error {
	if e.markers != nil {
		return nil
	}
	// set markers early so that we don't call getMarkers again from Expect
	e.markers = make(map[string]astutil.Range)
	return e.Expect(map[string]any{
		markMethod: e.Mark,
	})
}

var (
	noteType       = reflect.TypeFor[*expect.Note]()
	identifierType = reflect.TypeFor[expect.Identifier]()
	posType        = reflect.TypeFor[token.Pos]()
	positionType   = reflect.TypeFor[token.Position]()
	rangeType      = reflect.TypeFor[astutil.Range]()
	fsetType       = reflect.TypeFor[*token.FileSet]()
	regexType      = reflect.TypeFor[*regexp.Regexp]()
	exportedType   = reflect.TypeFor[*Exported]()
)

// converter converts from a marker's argument parsed from the comment to
// reflect values passed to the method during Invoke.
// It takes the args remaining, and returns the args it did not consume.
// This allows a converter to consume 0 args for well known types, or multiple
// args for compound types.
type converter func(*expect.Note, []any) (reflect.Value, []any, error)

// method is used to track information about Invoke methods that is expensive to
// calculate so that we can work it out once rather than per marker.
type method struct {
	f          reflect.Value // the reflect value of the passed in method
	converters []converter   // the parameter converters for the method
}

// buildConverter works out what function should be used to go from an ast expressions to a reflect
// value of the type expected by a method.
// It is called when only the target type is know, it returns converters that are flexible across
// all supported expression types for that target type.
func (e *Exported) buildConverter(pt reflect.Type) (converter, error) {
	switch {
	case pt == noteType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			return reflect.ValueOf(n), args, nil
		}, nil
	case pt == fsetType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			return reflect.ValueOf(e.ExpectFileSet), args, nil
		}, nil
	case pt == exportedType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			return reflect.ValueOf(e), args, nil
		}, nil
	case pt == posType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			r, remains, err := e.rangeConverter(n, args)
			if err != nil {
				return reflect.Value{}, nil, err
			}
			return reflect.ValueOf(r.Start), remains, nil
		}, nil
	case pt == positionType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			r, remains, err := e.rangeConverter(n, args)
			if err != nil {
				return reflect.Value{}, nil, err
			}
			return reflect.ValueOf(e.ExpectFileSet.Position(r.Start)), remains, nil
		}, nil
	case pt == rangeType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			r, remains, err := e.rangeConverter(n, args)
			if err != nil {
				return reflect.Value{}, nil, err
			}
			return reflect.ValueOf(r), remains, nil
		}, nil
	case pt == identifierType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			if len(args) < 1 {
				return reflect.Value{}, nil, fmt.Errorf("missing argument")
			}
			arg := args[0]
			args = args[1:]
			switch arg := arg.(type) {
			case expect.Identifier:
				return reflect.ValueOf(arg), args, nil
			default:
				return reflect.Value{}, nil, fmt.Errorf("cannot convert %v to string", arg)
			}
		}, nil

	case pt == regexType:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			if len(args) < 1 {
				return reflect.Value{}, nil, fmt.Errorf("missing argument")
			}
			arg := args[0]
			args = args[1:]
			if _, ok := arg.(*regexp.Regexp); !ok {
				return reflect.Value{}, nil, fmt.Errorf("cannot convert %v to *regexp.Regexp", arg)
			}
			return reflect.ValueOf(arg), args, nil
		}, nil

	case pt.Kind() == reflect.String:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			if len(args) < 1 {
				return reflect.Value{}, nil, fmt.Errorf("missing argument")
			}
			arg := args[0]
			args = args[1:]
			switch arg := arg.(type) {
			case expect.Identifier:
				return reflect.ValueOf(string(arg)), args, nil
			case string:
				return reflect.ValueOf(arg), args, nil
			default:
				return reflect.Value{}, nil, fmt.Errorf("cannot convert %v to string", arg)
			}
		}, nil
	case pt.Kind() == reflect.Int64:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			if len(args) < 1 {
				return reflect.Value{}, nil, fmt.Errorf("missing argument")
			}
			arg := args[0]
			args = args[1:]
			switch arg := arg.(type) {
			case int64:
				return reflect.ValueOf(arg), args, nil
			default:
				return reflect.Value{}, nil, fmt.Errorf("cannot convert %v to int", arg)
			}
		}, nil
	case pt.Kind() == reflect.Bool:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			if len(args) < 1 {
				return reflect.Value{}, nil, fmt.Errorf("missing argument")
			}
			arg := args[0]
			args = args[1:]
			b, ok := arg.(bool)
			if !ok {
				return reflect.Value{}, nil, fmt.Errorf("cannot convert %v to bool", arg)
			}
			return reflect.ValueOf(b), args, nil
		}, nil
	case pt.Kind() == reflect.Slice:
		return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
			converter, err := e.buildConverter(pt.Elem())
			if err != nil {
				return reflect.Value{}, nil, err
			}
			result := reflect.MakeSlice(reflect.SliceOf(pt.Elem()), 0, len(args))
			for range args {
				value, remains, err := converter(n, args)
				if err != nil {
					return reflect.Value{}, nil, err
				}
				result = reflect.Append(result, value)
				args = remains
			}
			return result, args, nil
		}, nil
	default:
		if pt.Kind() == reflect.Interface && pt.NumMethod() == 0 {
			return func(n *expect.Note, args []any) (reflect.Value, []any, error) {
				if len(args) < 1 {
					return reflect.Value{}, nil, fmt.Errorf("missing argument")
				}
				return reflect.ValueOf(args[0]), args[1:], nil
			}, nil
		}
		return nil, fmt.Errorf("param has unexpected type %v (kind %v)", pt, pt.Kind())
	}
}

func (e *Exported) rangeConverter(n *expect.Note, args []any) (astutil.Range, []any, error) {
	tokFile := e.ExpectFileSet.File(n.Pos)
	if len(args) < 1 {
		return astutil.Range{}, nil, fmt.Errorf("missing argument")
	}
	arg := args[0]
	args = args[1:]
	switch arg := arg.(type) {
	case expect.Identifier:
		// handle the special identifiers
		switch arg {
		case eofIdentifier:
			// end of file identifier
			eof := tokFile.Pos(tokFile.Size())
			return newRange(tokFile, eof, eof), args, nil
		default:
			// look up a marker by name
			mark, ok := e.markers[string(arg)]
			if !ok {
				return astutil.Range{}, nil, fmt.Errorf("cannot find marker %v", arg)
			}
			return mark, args, nil
		}
	case string:
		start, end, err := expect.MatchBefore(tokFile, e.FileContents, n.Pos, arg)
		if err != nil {
			return astutil.Range{}, nil, err
		}
		if !start.IsValid() {
			return astutil.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", tokFile.Position(n.Pos), arg)
		}
		return newRange(tokFile, start, end), args, nil
	case *regexp.Regexp:
		start, end, err := expect.MatchBefore(tokFile, e.FileContents, n.Pos, arg)
		if err != nil {
			return astutil.Range{}, nil, err
		}
		if !start.IsValid() {
			return astutil.Range{}, nil, fmt.Errorf("%v: pattern %s did not match", tokFile.Position(n.Pos), arg)
		}
		return newRange(tokFile, start, end), args, nil
	default:
		return astutil.Range{}, nil, fmt.Errorf("cannot convert %v to pos", arg)
	}
}

// newRange creates a new Range from two valid positions within the specified token.File.
func newRange(file *token.File, start, end token.Pos) astutil.Range {
	fileBase := file.Base()
	fileEnd := fileBase + file.Size()
	if !start.IsValid() {
		panic("invalid start token.Pos")
	}
	if !end.IsValid() {
		panic("invalid end token.Pos")
	}
	if int(start) < fileBase || int(start) > fileEnd {
		panic(fmt.Sprintf("invalid start: %d not in [%d, %d]", start, fileBase, fileEnd))
	}
	if int(end) < fileBase || int(end) > fileEnd {
		panic(fmt.Sprintf("invalid end: %d not in [%d, %d]", end, fileBase, fileEnd))
	}
	if start > end {
		panic("invalid start: greater than end")
	}
	return astutil.RangeOf(start, end)
}


================================================
FILE: internal/packagestest/expect_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest_test

import (
	"go/token"
	"testing"

	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/packagestest"
)

func TestExpect(t *testing.T) {
	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{{
		Name:  "golang.org/fake",
		Files: packagestest.MustCopyFileTree("testdata"),
	}})
	defer exported.Cleanup()
	checkCount := 0
	if err := exported.Expect(map[string]any{
		"check": func(src, target token.Position) {
			checkCount++
		},
		"boolArg": func(n *expect.Note, yes, no bool) {
			if !yes {
				t.Errorf("Expected boolArg first param to be true")
			}
			if no {
				t.Errorf("Expected boolArg second param to be false")
			}
		},
		"intArg": func(n *expect.Note, i int64) {
			if i != 42 {
				t.Errorf("Expected intarg to be 42")
			}
		},
		"stringArg": func(n *expect.Note, name expect.Identifier, value string) {
			if string(name) != value {
				t.Errorf("Got string arg %v expected %v", value, name)
			}
		},
		"directNote": func(n *expect.Note) {},
		"range": func(r astutil.Range) {
			if r.Start == token.NoPos {
				t.Errorf("Range had no valid starting position")
			}
			if r.EndPos == token.NoPos {
				t.Errorf("Range had no valid ending position")
			} else if r.EndPos <= r.Start {
				t.Errorf("Range ending was not greater than start")
			}
		},
		"checkEOF": func(n *expect.Note, p token.Pos) {
			if p <= n.Pos {
				t.Errorf("EOF was before the checkEOF note")
			}
		},
	}); err != nil {
		t.Fatal(err)
	}
	// We expect to have walked the @check annotations in all .go files,
	// including _test.go files (XTest or otherwise). But to have walked the
	// non-_test.go files only once. Hence wantCheck = 3 (testdata/test.go) + 1
	// (testdata/test_test.go) + 1 (testdata/x_test.go)
	wantCheck := 7
	if wantCheck != checkCount {
		t.Fatalf("Expected @check count of %v; got %v", wantCheck, checkCount)
	}
}


================================================
FILE: internal/packagestest/export.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package packagestest creates temporary projects on disk for testing go tools on.

By changing the exporter used, you can create projects for multiple build
systems from the same description, and run the same tests on them in many
cases.

# Example

As an example of packagestest use, consider the following test that runs
the 'go list' command on the specified modules:

	// TestGoList exercises the 'go list' command in module mode and in GOPATH mode.
	func TestGoList(t *testing.T) { packagestest.TestAll(t, testGoList) }
	func testGoList(t *testing.T, x packagestest.Exporter) {
		e := packagestest.Export(t, x, []packagestest.Module{
			{
				Name: "gopher.example/repoa",
				Files: map[string]interface{}{
					"a/a.go": "package a",
				},
			},
			{
				Name: "gopher.example/repob",
				Files: map[string]interface{}{
					"b/b.go": "package b",
				},
			},
		})
		defer e.Cleanup()

		cmd := exec.Command("go", "list", "gopher.example/...")
		cmd.Dir = e.Config.Dir
		cmd.Env = e.Config.Env
		out, err := cmd.Output()
		if err != nil {
			t.Fatal(err)
		}
		t.Logf("'go list gopher.example/...' with %s mode layout:\n%s", x.Name(), out)
	}

TestGoList uses TestAll to exercise the 'go list' command with all
exporters known to packagestest. Currently, packagestest includes
exporters that produce module mode layouts and GOPATH mode layouts.
Running the test with verbose output will print:

	=== RUN   TestGoList
	=== RUN   TestGoList/GOPATH
	=== RUN   TestGoList/Modules
	--- PASS: TestGoList (0.21s)
	    --- PASS: TestGoList/GOPATH (0.03s)
	        main_test.go:36: 'go list gopher.example/...' with GOPATH mode layout:
	            gopher.example/repoa/a
	            gopher.example/repob/b
	    --- PASS: TestGoList/Modules (0.18s)
	        main_test.go:36: 'go list gopher.example/...' with Modules mode layout:
	            gopher.example/repoa/a
	            gopher.example/repob/b
*/
package packagestest

import (
	"errors"
	"flag"
	"fmt"
	"go/token"
	"io"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/testenv"
)

var (
	skipCleanup = flag.Bool("skip-cleanup", false, "Do not delete the temporary export folders") // for debugging
)

// ErrUnsupported indicates an error due to an operation not supported on the
// current platform.
var ErrUnsupported = errors.New("operation is not supported")

// Module is a representation of a go module.
type Module struct {
	// Name is the base name of the module as it would be in the go.mod file.
	Name string
	// Files is the set of source files for all packages that make up the module.
	// The keys are the file fragment that follows the module name, the value can
	// be a string or byte slice, in which case it is the contents of the
	// file, otherwise it must be a Writer function.
	Files map[string]any

	// Overlay is the set of source file overlays for the module.
	// The keys are the file fragment as in the Files configuration.
	// The values are the in memory overlay content for the file.
	Overlay map[string][]byte
}

// A Writer is a function that writes out a test file.
// It is provided the name of the file to write, and may return an error if it
// cannot write the file.
// These are used as the content of the Files map in a Module.
type Writer func(filename string) error

// Exported is returned by the Export function to report the structure that was produced on disk.
type Exported struct {
	// Config is a correctly configured packages.Config ready to be passed to packages.Load.
	// Exactly what it will contain varies depending on the Exporter being used.
	Config *packages.Config

	// Modules is the module description that was used to produce this exported data set.
	Modules []Module

	ExpectFileSet *token.FileSet // The file set used when parsing expectations

	Exporter Exporter                     // the exporter used
	temp     string                       // the temporary directory that was exported to
	primary  string                       // the first non GOROOT module that was exported
	written  map[string]map[string]string // the full set of exported files
	notes    []*expect.Note               // The list of expectations extracted from go source files
	markers  map[string]astutil.Range     // The set of markers extracted from go source files
}

// Exporter implementations are responsible for converting from the generic description of some
// test data to a driver specific file layout.
type Exporter interface {
	// Name reports the name of the exporter, used in logging and sub-test generation.
	Name() string
	// Filename reports the system filename for test data source file.
	// It is given the base directory, the module the file is part of and the filename fragment to
	// work from.
	Filename(exported *Exported, module, fragment string) string
	// Finalize is called once all files have been written to write any extra data needed and modify
	// the Config to match. It is handed the full list of modules that were encountered while writing
	// files.
	Finalize(exported *Exported) error
}

// All is the list of known exporters.
// This is used by TestAll to run tests with all the exporters.
var All = []Exporter{GOPATH, Modules}

// TestAll invokes the testing function once for each exporter registered in
// the All global.
// Each exporter will be run as a sub-test named after the exporter being used.
func TestAll(t *testing.T, f func(*testing.T, Exporter)) {
	t.Helper()
	for _, e := range All {
		t.Run(e.Name(), func(t *testing.T) {
			t.Helper()
			f(t, e)
		})
	}
}

// BenchmarkAll invokes the testing function once for each exporter registered in
// the All global.
// Each exporter will be run as a sub-test named after the exporter being used.
func BenchmarkAll(b *testing.B, f func(*testing.B, Exporter)) {
	b.Helper()
	for _, e := range All {
		b.Run(e.Name(), func(b *testing.B) {
			b.Helper()
			f(b, e)
		})
	}
}

// Export is called to write out a test directory from within a test function.
// It takes the exporter and the build system agnostic module descriptions, and
// uses them to build a temporary directory.
// It returns an Exported with the results of the export.
// The Exported.Config is prepared for loading from the exported data.
// You must invoke Exported.Cleanup on the returned value to clean up.
// The file deletion in the cleanup can be skipped by setting the skip-cleanup
// flag when invoking the test, allowing the temporary directory to be left for
// debugging tests.
//
// If the Writer for any file within any module returns an error equivalent to
// ErrUnspported, Export skips the test.
func Export(t testing.TB, exporter Exporter, modules []Module) *Exported {
	t.Helper()
	if exporter == Modules {
		testenv.NeedsTool(t, "go")
	}

	dirname := strings.Replace(t.Name(), "/", "_", -1)
	dirname = strings.Replace(dirname, "#", "_", -1) // duplicate subtests get a #NNN suffix.
	temp, err := os.MkdirTemp("", dirname)
	if err != nil {
		t.Fatal(err)
	}
	exported := &Exported{
		Config: &packages.Config{
			Dir:     temp,
			Env:     append(os.Environ(), "GOPACKAGESDRIVER=off", "GOROOT="), // Clear GOROOT to work around #32849.
			Overlay: make(map[string][]byte),
			Tests:   true,
			Mode:    packages.LoadImports,
		},
		Modules:       modules,
		Exporter:      exporter,
		temp:          temp,
		primary:       modules[0].Name,
		written:       map[string]map[string]string{},
		ExpectFileSet: token.NewFileSet(),
	}
	if testing.Verbose() {
		exported.Config.Logf = t.Logf
	}
	defer func() {
		if t.Failed() || t.Skipped() {
			exported.Cleanup()
		}
	}()
	for _, module := range modules {
		// Create all parent directories before individual files. If any file is a
		// symlink to a directory, that directory must exist before the symlink is
		// created or else it may be created with the wrong type on Windows.
		// (See https://golang.org/issue/39183.)
		for fragment := range module.Files {
			fullpath := exporter.Filename(exported, module.Name, filepath.FromSlash(fragment))
			if err := os.MkdirAll(filepath.Dir(fullpath), 0755); err != nil {
				t.Fatal(err)
			}
		}

		for fragment, value := range module.Files {
			fullpath := exporter.Filename(exported, module.Name, filepath.FromSlash(fragment))
			written, ok := exported.written[module.Name]
			if !ok {
				written = map[string]string{}
				exported.written[module.Name] = written
			}
			written[fragment] = fullpath
			switch value := value.(type) {
			case Writer:
				if err := value(fullpath); err != nil {
					if errors.Is(err, ErrUnsupported) {
						t.Skip(err)
					}
					t.Fatal(err)
				}
			case string:
				if err := os.WriteFile(fullpath, []byte(value), 0644); err != nil {
					t.Fatal(err)
				}
			default:
				t.Fatalf("Invalid type %T in files, must be string or Writer", value)
			}
		}
		for fragment, value := range module.Overlay {
			fullpath := exporter.Filename(exported, module.Name, filepath.FromSlash(fragment))
			exported.Config.Overlay[fullpath] = value
		}
	}
	if err := exporter.Finalize(exported); err != nil {
		t.Fatal(err)
	}
	testenv.NeedsGoPackagesEnv(t, exported.Config.Env)
	return exported
}

// Script returns a Writer that writes out contents to the file and sets the
// executable bit on the created file.
// It is intended for source files that are shell scripts.
func Script(contents string) Writer {
	return func(filename string) error {
		return os.WriteFile(filename, []byte(contents), 0755)
	}
}

// Link returns a Writer that creates a hard link from the specified source to
// the required file.
// This is used to link testdata files into the generated testing tree.
//
// If hard links to source are not supported on the destination filesystem, the
// returned Writer returns an error for which errors.Is(_, ErrUnsupported)
// returns true.
func Link(source string) Writer {
	return func(filename string) error {
		linkErr := os.Link(source, filename)

		if linkErr != nil && !builderMustSupportLinks() {
			// Probe to figure out whether Link failed because the Link operation
			// isn't supported.
			if stat, err := openAndStat(source); err == nil {
				if err := createEmpty(filename, stat.Mode()); err == nil {
					// Successfully opened the source and created the destination,
					// but the result is empty and not a hard-link.
					return &os.PathError{Op: "Link", Path: filename, Err: ErrUnsupported}
				}
			}
		}

		return linkErr
	}
}

// Symlink returns a Writer that creates a symlink from the specified source to the
// required file.
// This is used to link testdata files into the generated testing tree.
//
// If symlinks to source are not supported on the destination filesystem, the
// returned Writer returns an error for which errors.Is(_, ErrUnsupported)
// returns true.
func Symlink(source string) Writer {
	if !strings.HasPrefix(source, ".") {
		if absSource, err := filepath.Abs(source); err == nil {
			if _, err := os.Stat(source); !os.IsNotExist(err) {
				source = absSource
			}
		}
	}
	return func(filename string) error {
		symlinkErr := os.Symlink(source, filename)

		if symlinkErr != nil && !builderMustSupportLinks() {
			// Probe to figure out whether Symlink failed because the Symlink
			// operation isn't supported.
			fullSource := source
			if !filepath.IsAbs(source) {
				// Compute the target path relative to the parent of filename, not the
				// current working directory.
				fullSource = filepath.Join(filename, "..", source)
			}
			stat, err := openAndStat(fullSource)
			mode := os.ModePerm
			if err == nil {
				mode = stat.Mode()
			} else if !errors.Is(err, os.ErrNotExist) {
				// We couldn't open the source, but it might exist. We don't expect to be
				// able to portably create a symlink to a file we can't see.
				return symlinkErr
			}

			if err := createEmpty(filename, mode|0644); err == nil {
				// Successfully opened the source (or verified that it does not exist) and
				// created the destination, but we couldn't create it as a symlink.
				// Probably the OS just doesn't support symlinks in this context.
				return &os.PathError{Op: "Symlink", Path: filename, Err: ErrUnsupported}
			}
		}

		return symlinkErr
	}
}

// builderMustSupportLinks reports whether we are running on a Go builder
// that is known to support hard and symbolic links.
func builderMustSupportLinks() bool {
	if os.Getenv("GO_BUILDER_NAME") == "" {
		// Any OS can be configured to mount an exotic filesystem.
		// Don't make assumptions about what users are running.
		return false
	}

	switch runtime.GOOS {
	case "windows", "plan9":
		// Some versions of Windows and all versions of plan9 do not support
		// symlinks by default.
		return false

	default:
		// All other platforms should support symlinks by default, and our builders
		// should not do anything unusual that would violate that.
		return true
	}
}

// openAndStat attempts to open source for reading.
func openAndStat(source string) (os.FileInfo, error) {
	src, err := os.Open(source)
	if err != nil {
		return nil, err
	}
	stat, err := src.Stat()
	src.Close()
	if err != nil {
		return nil, err
	}
	return stat, nil
}

// createEmpty creates an empty file or directory (depending on mode)
// at dst, with the same permissions as mode.
func createEmpty(dst string, mode os.FileMode) error {
	if mode.IsDir() {
		return os.Mkdir(dst, mode.Perm())
	}

	f, err := os.OpenFile(dst, os.O_WRONLY|os.O_CREATE|os.O_EXCL, mode.Perm())
	if err != nil {
		return err
	}
	if err := f.Close(); err != nil {
		os.Remove(dst) // best-effort
		return err
	}

	return nil
}

// Copy returns a Writer that copies a file from the specified source to the
// required file.
// This is used to copy testdata files into the generated testing tree.
func Copy(source string) Writer {
	return func(filename string) error {
		stat, err := os.Stat(source)
		if err != nil {
			return err
		}
		if !stat.Mode().IsRegular() {
			// cannot copy non-regular files (e.g., directories,
			// symlinks, devices, etc.)
			return fmt.Errorf("cannot copy non regular file %s", source)
		}
		return copyFile(filename, source, stat.Mode().Perm())
	}
}

func copyFile(dest, source string, perm os.FileMode) error {
	src, err := os.Open(source)
	if err != nil {
		return err
	}
	defer src.Close()

	dst, err := os.OpenFile(dest, os.O_WRONLY|os.O_CREATE|os.O_EXCL, perm)
	if err != nil {
		return err
	}

	_, err = io.Copy(dst, src)
	if closeErr := dst.Close(); err == nil {
		err = closeErr
	}
	return err
}

// GroupFilesByModules attempts to map directories to the modules within each directory.
// This function assumes that the folder is structured in the following way:
//
//	dir/
//		primarymod/
//			*.go files
//			packages
//			go.mod (optional)
//		modules/
//			repoa/
//				mod1/
//					*.go files
//					packages
//					go.mod (optional)
//
// It scans the directory tree anchored at root and adds a Copy writer to the
// map for every file found.
// This is to enable the common case in tests where you have a full copy of the
// package in your testdata.
func GroupFilesByModules(root string) ([]Module, error) {
	root = filepath.FromSlash(root)
	primarymodPath := filepath.Join(root, "primarymod")

	_, err := os.Stat(primarymodPath)
	if os.IsNotExist(err) {
		return nil, fmt.Errorf("could not find primarymod folder within %s", root)
	}

	primarymod := &Module{
		Name:    root,
		Files:   make(map[string]any),
		Overlay: make(map[string][]byte),
	}
	mods := map[string]*Module{
		root: primarymod,
	}
	modules := []Module{*primarymod}

	if err := filepath.Walk(primarymodPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			return nil
		}
		fragment, err := filepath.Rel(primarymodPath, path)
		if err != nil {
			return err
		}
		primarymod.Files[filepath.ToSlash(fragment)] = Copy(path)
		return nil
	}); err != nil {
		return nil, err
	}

	modulesPath := filepath.Join(root, "modules")
	if _, err := os.Stat(modulesPath); os.IsNotExist(err) {
		return modules, nil
	}

	var currentRepo, currentModule string
	updateCurrentModule := func(dir string) {
		if dir == currentModule {
			return
		}
		// Handle the case where we step into a nested directory that is a module
		// and then step out into the parent which is also a module.
		// Example:
		// - repoa
		//   - moda
		//     - go.mod
		//     - v2
		//       - go.mod
		//     - what.go
		//   - modb
		for dir != root {
			if mods[dir] != nil {
				currentModule = dir
				return
			}
			dir = filepath.Dir(dir)
		}
	}

	if err := filepath.Walk(modulesPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		enclosingDir := filepath.Dir(path)
		// If the path is not a directory, then we want to add the path to
		// the files map of the currentModule.
		if !info.IsDir() {
			updateCurrentModule(enclosingDir)
			fragment, err := filepath.Rel(currentModule, path)
			if err != nil {
				return err
			}
			mods[currentModule].Files[filepath.ToSlash(fragment)] = Copy(path)
			return nil
		}
		// If the path is a directory and it's enclosing folder is equal to
		// the modules folder, then the path is a new repo.
		if enclosingDir == modulesPath {
			currentRepo = path
			return nil
		}
		// If the path is a directory and it's enclosing folder is not the same
		// as the current repo and it is not of the form `v1`,`v2`,...
		// then the path is a folder/package of the current module.
		if enclosingDir != currentRepo && !versionSuffixRE.MatchString(filepath.Base(path)) {
			return nil
		}
		// If the path is a directory and it's enclosing folder is the current repo
		// then the path is a new module.
		module, err := filepath.Rel(modulesPath, path)
		if err != nil {
			return err
		}
		mods[path] = &Module{
			Name:    filepath.ToSlash(module),
			Files:   make(map[string]any),
			Overlay: make(map[string][]byte),
		}
		currentModule = path
		modules = append(modules, *mods[path])
		return nil
	}); err != nil {
		return nil, err
	}
	return modules, nil
}

// MustCopyFileTree returns a file set for a module based on a real directory tree.
// It scans the directory tree anchored at root and adds a Copy writer to the
// map for every file found. It skips copying files in nested modules.
// This is to enable the common case in tests where you have a full copy of the
// package in your testdata.
// This will panic if there is any kind of error trying to walk the file tree.
func MustCopyFileTree(root string) map[string]any {
	result := map[string]any{}
	if err := filepath.Walk(filepath.FromSlash(root), func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return err
		}
		if info.IsDir() {
			// skip nested modules.
			if path != root {
				if fi, err := os.Stat(filepath.Join(path, "go.mod")); err == nil && !fi.IsDir() {
					return filepath.SkipDir
				}
			}
			return nil
		}
		fragment, err := filepath.Rel(root, path)
		if err != nil {
			return err
		}
		result[filepath.ToSlash(fragment)] = Copy(path)
		return nil
	}); err != nil {
		log.Panic(fmt.Sprintf("MustCopyFileTree failed: %v", err))
	}
	return result
}

// Cleanup removes the temporary directory (unless the --skip-cleanup flag was set)
// It is safe to call cleanup multiple times.
func (e *Exported) Cleanup() {
	if e.temp == "" {
		return
	}
	if *skipCleanup {
		log.Printf("Skipping cleanup of temp dir: %s", e.temp)
		return
	}
	// Make everything read-write so that the Module exporter's module cache can be deleted.
	filepath.Walk(e.temp, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			return nil
		}
		if info.IsDir() {
			os.Chmod(path, 0777)
		}
		return nil
	})
	os.RemoveAll(e.temp) // ignore errors
	e.temp = ""
}

// Temp returns the temporary directory that was generated.
func (e *Exported) Temp() string {
	return e.temp
}

// File returns the full path for the given module and file fragment.
func (e *Exported) File(module, fragment string) string {
	if m := e.written[module]; m != nil {
		return m[fragment]
	}
	return ""
}

// FileContents returns the contents of the specified file.
// It will use the overlay if the file is present, otherwise it will read it
// from disk.
func (e *Exported) FileContents(filename string) ([]byte, error) {
	if content, found := e.Config.Overlay[filename]; found {
		return content, nil
	}
	content, err := os.ReadFile(filename)
	if err != nil {
		return nil, err
	}
	return content, nil
}


================================================
FILE: internal/packagestest/export_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest_test

import (
	"os"
	"path/filepath"
	"reflect"
	"sort"
	"testing"

	"golang.org/x/tools/internal/packagestest"
)

var testdata = []packagestest.Module{{
	Name: "golang.org/fake1",
	Files: map[string]any{
		"a.go": packagestest.Symlink("testdata/a.go"), // broken symlink
		"b.go": "invalid file contents",
	},
	Overlay: map[string][]byte{
		"b.go": []byte("package fake1"),
		"c.go": []byte("package fake1"),
	},
}, {
	Name: "golang.org/fake2",
	Files: map[string]any{
		"other/a.go": "package fake2",
	},
}, {
	Name: "golang.org/fake2/v2",
	Files: map[string]any{
		"other/a.go": "package fake2",
	},
}, {
	Name: "golang.org/fake3@v1.0.0",
	Files: map[string]any{
		"other/a.go": "package fake3",
	},
}, {
	Name: "golang.org/fake3@v1.1.0",
	Files: map[string]any{
		"other/a.go": "package fake3",
	},
}}

type fileTest struct {
	module, fragment, expect string
	check                    func(t *testing.T, exported *packagestest.Exported, filename string)
}

func checkFiles(t *testing.T, exported *packagestest.Exported, tests []fileTest) {
	for _, test := range tests {
		expect := filepath.Join(exported.Temp(), filepath.FromSlash(test.expect))
		got := exported.File(test.module, test.fragment)
		if got == "" {
			t.Errorf("File %v missing from the output", expect)
		} else if got != expect {
			t.Errorf("Got file %v, expected %v", got, expect)
		}
		if test.check != nil {
			test.check(t, exported, got)
		}
	}
}

func checkLink(expect string) func(t *testing.T, exported *packagestest.Exported, filename string) {
	expect = filepath.FromSlash(expect)
	return func(t *testing.T, exported *packagestest.Exported, filename string) {
		if target, err := os.Readlink(filename); err != nil {
			t.Errorf("Error checking link %v: %v", filename, err)
		} else if target != expect {
			t.Errorf("Link %v does not match, got %v expected %v", filename, target, expect)
		}
	}
}

func checkContent(expect string) func(t *testing.T, exported *packagestest.Exported, filename string) {
	return func(t *testing.T, exported *packagestest.Exported, filename string) {
		if content, err := exported.FileContents(filename); err != nil {
			t.Errorf("Error reading %v: %v", filename, err)
		} else if string(content) != expect {
			t.Errorf("Content of %v does not match, got %v expected %v", filename, string(content), expect)
		}
	}
}

func TestGroupFilesByModules(t *testing.T) {
	for _, tt := range []struct {
		testdir string
		want    []packagestest.Module
	}{
		{
			testdir: "testdata/groups/one",
			want: []packagestest.Module{
				{
					Name: "testdata/groups/one",
					Files: map[string]any{
						"main.go": true,
					},
				},
				{
					Name: "example.com/extra",
					Files: map[string]any{
						"help.go": true,
					},
				},
			},
		},
		{
			testdir: "testdata/groups/two",
			want: []packagestest.Module{
				{
					Name: "testdata/groups/two",
					Files: map[string]any{
						"main.go":           true,
						"expect/yo.go":      true,
						"expect/yo_test.go": true,
					},
				},
				{
					Name: "example.com/extra",
					Files: map[string]any{
						"yo.go":        true,
						"geez/help.go": true,
					},
				},
				{
					Name: "example.com/extra/v2",
					Files: map[string]any{
						"me.go":        true,
						"geez/help.go": true,
					},
				},
				{
					Name: "example.com/tempmod",
					Files: map[string]any{
						"main.go": true,
					},
				},
				{
					Name: "example.com/what@v1.0.0",
					Files: map[string]any{
						"main.go": true,
					},
				},
				{
					Name: "example.com/what@v1.1.0",
					Files: map[string]any{
						"main.go": true,
					},
				},
			},
		},
	} {
		t.Run(tt.testdir, func(t *testing.T) {
			got, err := packagestest.GroupFilesByModules(tt.testdir)
			if err != nil {
				t.Fatalf("could not group files %v", err)
			}
			if len(got) != len(tt.want) {
				t.Fatalf("%s: wanted %d modules but got %d", tt.testdir, len(tt.want), len(got))
			}
			for i, w := range tt.want {
				g := got[i]
				if filepath.FromSlash(g.Name) != filepath.FromSlash(w.Name) {
					t.Fatalf("%s: wanted module[%d].Name to be %s but got %s", tt.testdir, i, filepath.FromSlash(w.Name), filepath.FromSlash(g.Name))
				}
				for fh := range w.Files {
					if _, ok := g.Files[fh]; !ok {
						t.Fatalf("%s, module[%d]: wanted %s but could not find", tt.testdir, i, fh)
					}
				}
				for fh := range g.Files {
					if _, ok := w.Files[fh]; !ok {
						t.Fatalf("%s, module[%d]: found unexpected file %s", tt.testdir, i, fh)
					}
				}
			}
		})
	}
}

func TestMustCopyFiles(t *testing.T) {
	// Create the following test directory structure in a temporary directory.
	src := map[string]string{
		// copies all files under the specified directory.
		"go.mod": "module example.com",
		"m.go":   "package m",
		"a/a.go": "package a",
		// contents from a nested module shouldn't be copied.
		"nested/go.mod": "module example.com/nested",
		"nested/m.go":   "package nested",
		"nested/b/b.go": "package b",
	}

	tmpDir, err := os.MkdirTemp("", t.Name())
	if err != nil {
		t.Fatalf("failed to create a temporary directory: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	for fragment, contents := range src {
		fullpath := filepath.Join(tmpDir, filepath.FromSlash(fragment))
		if err := os.MkdirAll(filepath.Dir(fullpath), 0755); err != nil {
			t.Fatal(err)
		}
		if err := os.WriteFile(fullpath, []byte(contents), 0644); err != nil {
			t.Fatal(err)
		}
	}

	copied := packagestest.MustCopyFileTree(tmpDir)
	var got []string
	for fragment := range copied {
		got = append(got, filepath.ToSlash(fragment))
	}
	want := []string{"go.mod", "m.go", "a/a.go"}

	sort.Strings(got)
	sort.Strings(want)
	if !reflect.DeepEqual(got, want) {
		t.Errorf("packagestest.MustCopyFileTree = %v, want %v", got, want)
	}

	// packagestest.Export is happy.
	exported := packagestest.Export(t, packagestest.Modules, []packagestest.Module{{
		Name:  "example.com",
		Files: packagestest.MustCopyFileTree(tmpDir),
	}})
	defer exported.Cleanup()
}


================================================
FILE: internal/packagestest/gopath.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest

import (
	"path"
	"path/filepath"
)

// GOPATH is the exporter that produces GOPATH layouts.
// Each "module" is put in it's own GOPATH entry to help test complex cases.
// Given the two files
//
//	golang.org/repoa#a/a.go
//	golang.org/repob#b/b.go
//
// You would get the directory layout
//
//	/sometemporarydirectory
//	├── repoa
//	│   └── src
//	│       └── golang.org
//	│           └── repoa
//	│               └── a
//	│                   └── a.go
//	└── repob
//	    └── src
//	        └── golang.org
//	            └── repob
//	                └── b
//	                    └── b.go
//
// GOPATH would be set to
//
//	/sometemporarydirectory/repoa;/sometemporarydirectory/repob
//
// and the working directory would be
//
//	/sometemporarydirectory/repoa/src
var GOPATH = gopath{}

type gopath struct{}

func (gopath) Name() string {
	return "GOPATH"
}

func (gopath) Filename(exported *Exported, module, fragment string) string {
	return filepath.Join(gopathDir(exported, module), "src", module, fragment)
}

func (gopath) Finalize(exported *Exported) error {
	exported.Config.Env = append(exported.Config.Env, "GO111MODULE=off")
	gopath := ""
	for module := range exported.written {
		if gopath != "" {
			gopath += string(filepath.ListSeparator)
		}
		dir := gopathDir(exported, module)
		gopath += dir
		if module == exported.primary {
			exported.Config.Dir = filepath.Join(dir, "src")
		}
	}
	exported.Config.Env = append(exported.Config.Env, "GOPATH="+gopath)
	return nil
}

func gopathDir(exported *Exported, module string) string {
	dir := path.Base(module)
	if versionSuffixRE.MatchString(dir) {
		dir = path.Base(path.Dir(module)) + "_" + dir
	}
	return filepath.Join(exported.temp, dir)
}


================================================
FILE: internal/packagestest/gopath_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/internal/packagestest"
)

func TestGOPATHExport(t *testing.T) {
	exported := packagestest.Export(t, packagestest.GOPATH, testdata)
	defer exported.Cleanup()
	// Check that the cfg contains all the right bits
	var expectDir = filepath.Join(exported.Temp(), "fake1", "src")
	if exported.Config.Dir != expectDir {
		t.Errorf("Got working directory %v expected %v", exported.Config.Dir, expectDir)
	}
	checkFiles(t, exported, []fileTest{
		{"golang.org/fake1", "a.go", "fake1/src/golang.org/fake1/a.go", checkLink("testdata/a.go")},
		{"golang.org/fake1", "b.go", "fake1/src/golang.org/fake1/b.go", checkContent("package fake1")},
		{"golang.org/fake2", "other/a.go", "fake2/src/golang.org/fake2/other/a.go", checkContent("package fake2")},
		{"golang.org/fake2/v2", "other/a.go", "fake2_v2/src/golang.org/fake2/v2/other/a.go", checkContent("package fake2")},
	})
}


================================================
FILE: internal/packagestest/modules.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest

import (
	"bytes"
	"context"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"strings"

	"golang.org/x/tools/internal/gocommand"
	"golang.org/x/tools/internal/proxydir"
)

// Modules is the exporter that produces module layouts.
// Each "repository" is put in its own module, and the module file generated
// will have replace directives for all other modules.
// Given the two files
//
//	golang.org/repoa#a/a.go
//	golang.org/repob#b/b.go
//
// You would get the directory layout
//
//	/sometemporarydirectory
//	├── repoa
//	│   ├── a
//	│   │   └── a.go
//	│   └── go.mod
//	└── repob
//	    ├── b
//	    │   └── b.go
//	    └── go.mod
//
// and the working directory would be
//
//	/sometemporarydirectory/repoa
var Modules = modules{}

type modules struct{}

type moduleAtVersion struct {
	module  string
	version string
}

func (modules) Name() string {
	return "Modules"
}

func (modules) Filename(exported *Exported, module, fragment string) string {
	if module == exported.primary {
		return filepath.Join(primaryDir(exported), fragment)
	}
	return filepath.Join(moduleDir(exported, module), fragment)
}

func (modules) Finalize(exported *Exported) error {
	// Write out the primary module. This module can use symlinks and
	// other weird stuff, and will be the working dir for the go command.
	// It depends on all the other modules.
	primaryDir := primaryDir(exported)
	if err := os.MkdirAll(primaryDir, 0755); err != nil {
		return err
	}
	exported.Config.Dir = primaryDir
	if exported.written[exported.primary] == nil {
		exported.written[exported.primary] = make(map[string]string)
	}

	// Create a map of modulepath -> {module, version} for modulepaths
	// that are of the form `repoa/mod1@v1.1.0`.
	versions := make(map[string]moduleAtVersion)
	for module := range exported.written {
		if splt := strings.Split(module, "@"); len(splt) > 1 {
			versions[module] = moduleAtVersion{
				module:  splt[0],
				version: splt[1],
			}
		}
	}

	// If the primary module already has a go.mod, write the contents to a temp
	// go.mod for now and then we will reset it when we are getting all the markers.
	if gomod := exported.written[exported.primary]["go.mod"]; gomod != "" {
		contents, err := os.ReadFile(gomod)
		if err != nil {
			return err
		}
		if err := os.WriteFile(gomod+".temp", contents, 0644); err != nil {
			return err
		}
	}

	exported.written[exported.primary]["go.mod"] = filepath.Join(primaryDir, "go.mod")
	var primaryGomod bytes.Buffer
	fmt.Fprintf(&primaryGomod, "module %s\nrequire (\n", exported.primary)
	for other := range exported.written {
		if other == exported.primary {
			continue
		}
		version := moduleVersion(other)
		// If other is of the form `repo1/mod1@v1.1.0`,
		// then we need to extract the module and the version.
		if v, ok := versions[other]; ok {
			other = v.module
			version = v.version
		}
		fmt.Fprintf(&primaryGomod, "\t%v %v\n", other, version)
	}
	fmt.Fprintf(&primaryGomod, ")\n")
	if err := os.WriteFile(filepath.Join(primaryDir, "go.mod"), primaryGomod.Bytes(), 0644); err != nil {
		return err
	}

	// Create the mod cache so we can rename it later, even if we don't need it.
	if err := os.MkdirAll(modCache(exported), 0755); err != nil {
		return err
	}

	// Write out the go.mod files for the other modules.
	for module, files := range exported.written {
		if module == exported.primary {
			continue
		}
		dir := moduleDir(exported, module)
		modfile := filepath.Join(dir, "go.mod")
		// If other is of the form `repo1/mod1@v1.1.0`,
		// then we need to extract the module name without the version.
		if v, ok := versions[module]; ok {
			module = v.module
		}
		if err := os.WriteFile(modfile, []byte("module "+module+"\n"), 0644); err != nil {
			return err
		}
		files["go.mod"] = modfile
	}

	// Zip up all the secondary modules into the proxy dir.
	modProxyDir := filepath.Join(exported.temp, "modproxy")
	for module, files := range exported.written {
		if module == exported.primary {
			continue
		}
		version := moduleVersion(module)
		// If other is of the form `repo1/mod1@v1.1.0`,
		// then we need to extract the module and the version.
		if v, ok := versions[module]; ok {
			module = v.module
			version = v.version
		}
		if err := writeModuleFiles(modProxyDir, module, version, files); err != nil {
			return fmt.Errorf("creating module proxy dir for %v: %v", module, err)
		}
	}

	// Discard the original mod cache dir, which contained the files written
	// for us by Export.
	if err := os.Rename(modCache(exported), modCache(exported)+".orig"); err != nil {
		return err
	}
	exported.Config.Env = append(exported.Config.Env,
		"GO111MODULE=on",
		"GOPATH="+filepath.Join(exported.temp, "modcache"),
		"GOMODCACHE=",
		"GOPROXY="+proxydir.ToURL(modProxyDir),
		"GOSUMDB=off",
	)

	// Run go mod download to recreate the mod cache dir with all the extra
	// stuff in cache. All the files created by Export should be recreated.
	inv := gocommand.Invocation{
		Verb:       "mod",
		Args:       []string{"download", "all"},
		Env:        exported.Config.Env,
		BuildFlags: exported.Config.BuildFlags,
		WorkingDir: exported.Config.Dir,
	}
	_, err := new(gocommand.Runner).Run(context.Background(), inv)
	return err
}

func writeModuleFiles(rootDir, module, ver string, filePaths map[string]string) error {
	fileData := make(map[string][]byte)
	for name, path := range filePaths {
		contents, err := os.ReadFile(path)
		if err != nil {
			return err
		}
		fileData[name] = contents
	}
	return proxydir.WriteModuleVersion(rootDir, module, ver, fileData)
}

func modCache(exported *Exported) string {
	return filepath.Join(exported.temp, "modcache/pkg/mod")
}

func primaryDir(exported *Exported) string {
	return filepath.Join(exported.temp, path.Base(exported.primary))
}

func moduleDir(exported *Exported, module string) string {
	if strings.Contains(module, "@") {
		return filepath.Join(modCache(exported), module)
	}
	return filepath.Join(modCache(exported), path.Dir(module), path.Base(module)+"@"+moduleVersion(module))
}

var versionSuffixRE = regexp.MustCompile(`v\d+`)

func moduleVersion(module string) string {
	if versionSuffixRE.MatchString(path.Base(module)) {
		return path.Base(module) + ".0.0"
	}
	return "v1.0.0"
}


================================================
FILE: internal/packagestest/modules_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package packagestest_test

import (
	"path/filepath"
	"testing"

	"golang.org/x/tools/internal/packagestest"
)

func TestModulesExport(t *testing.T) {
	exported := packagestest.Export(t, packagestest.Modules, testdata)
	defer exported.Cleanup()
	// Check that the cfg contains all the right bits
	var expectDir = filepath.Join(exported.Temp(), "fake1")
	if exported.Config.Dir != expectDir {
		t.Errorf("Got working directory %v expected %v", exported.Config.Dir, expectDir)
	}
	checkFiles(t, exported, []fileTest{
		{"golang.org/fake1", "go.mod", "fake1/go.mod", nil},
		{"golang.org/fake1", "a.go", "fake1/a.go", checkLink("testdata/a.go")},
		{"golang.org/fake1", "b.go", "fake1/b.go", checkContent("package fake1")},
		{"golang.org/fake2", "go.mod", "modcache/pkg/mod/golang.org/fake2@v1.0.0/go.mod", nil},
		{"golang.org/fake2", "other/a.go", "modcache/pkg/mod/golang.org/fake2@v1.0.0/other/a.go", checkContent("package fake2")},
		{"golang.org/fake2/v2", "other/a.go", "modcache/pkg/mod/golang.org/fake2/v2@v2.0.0/other/a.go", checkContent("package fake2")},
		{"golang.org/fake3@v1.1.0", "other/a.go", "modcache/pkg/mod/golang.org/fake3@v1.1.0/other/a.go", checkContent("package fake3")},
		{"golang.org/fake3@v1.0.0", "other/a.go", "modcache/pkg/mod/golang.org/fake3@v1.0.0/other/a.go", nil},
	})
}


================================================
FILE: internal/packagestest/testdata/groups/one/modules/example.com/extra/help.go
================================================
package extra

================================================
FILE: internal/packagestest/testdata/groups/one/primarymod/main.go
================================================
package one

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/extra/geez/help.go
================================================
package example.com/extra/geez

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/extra/v2/geez/help.go
================================================
package example.com/extra/geez

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/extra/v2/me.go
================================================
package example.com/extra

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/extra/yo.go
================================================
package example.com/extra

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/tempmod/main.go
================================================
package example.com/tempmod

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/what@v1.0.0/main.go
================================================
package example.com/what

================================================
FILE: internal/packagestest/testdata/groups/two/modules/example.com/what@v1.1.0/main.go
================================================
package example.com/what

================================================
FILE: internal/packagestest/testdata/groups/two/primarymod/expect/yo.go
================================================
package expect

var X int //@check("X", "X")


================================================
FILE: internal/packagestest/testdata/groups/two/primarymod/expect/yo_test.go
================================================
package expect_test

import (
	"testdata/groups/two/expect"
	"testing"
)

func TestX(t *testing.T) {
	_ = expect.X //@check("X", "X")
}


================================================
FILE: internal/packagestest/testdata/groups/two/primarymod/main.go
================================================
package two

================================================
FILE: internal/packagestest/testdata/test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package fake1

// This is a test file for the behaviors in Exported.Expect.

type AThing string //@AThing,mark(StringThing, "AThing"),mark(REThing,re`.T.*g`)

type Match string //@check("Match",re`[[:upper:]]`)

//@check(AThing, StringThing)
//@check(AThing, REThing)

//@boolArg(true, false)
//@intArg(42)
//@stringArg(PlainString, "PlainString")
//@stringArg(IdentAsString,IdentAsString)
//@directNote()
//@range(AThing)

// The following test should remain at the bottom of the file
//@checkEOF(EOF)


================================================
FILE: internal/packagestest/testdata/test_test.go
================================================
package fake1

type ATestType string //@check("ATestType","ATestType")


================================================
FILE: internal/packagestest/testdata/x_test.go
================================================
package fake1_test

type AnXTestType string //@check("AnXTestType","AnXTestType")


================================================
FILE: internal/pkgbits/codes.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

// A Code is an enum value that can be encoded into bitstreams.
//
// Code types are preferable for enum types, because they allow
// Decoder to detect desyncs.
type Code interface {
	// Marker returns the SyncMarker for the Code's dynamic type.
	Marker() SyncMarker

	// Value returns the Code's ordinal value.
	Value() int
}

// A CodeVal distinguishes among go/constant.Value encodings.
type CodeVal int

func (c CodeVal) Marker() SyncMarker { return SyncVal }
func (c CodeVal) Value() int         { return int(c) }

// Note: These values are public and cannot be changed without
// updating the go/types importers.

const (
	ValBool CodeVal = iota
	ValString
	ValInt64
	ValBigInt
	ValBigRat
	ValBigFloat
)

// A CodeType distinguishes among go/types.Type encodings.
type CodeType int

func (c CodeType) Marker() SyncMarker { return SyncType }
func (c CodeType) Value() int         { return int(c) }

// Note: These values are public and cannot be changed without
// updating the go/types importers.

const (
	TypeBasic CodeType = iota
	TypeNamed
	TypePointer
	TypeSlice
	TypeArray
	TypeChan
	TypeMap
	TypeSignature
	TypeStruct
	TypeInterface
	TypeUnion
	TypeTypeParam
)

// A CodeObj distinguishes among go/types.Object encodings.
type CodeObj int

func (c CodeObj) Marker() SyncMarker { return SyncCodeObj }
func (c CodeObj) Value() int         { return int(c) }

// Note: These values are public and cannot be changed without
// updating the go/types importers.

const (
	ObjAlias CodeObj = iota
	ObjConst
	ObjType
	ObjFunc
	ObjVar
	ObjStub
)


================================================
FILE: internal/pkgbits/decoder.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

import (
	"encoding/binary"
	"errors"
	"fmt"
	"go/constant"
	"go/token"
	"io"
	"math/big"
	"os"
	"runtime"
	"strings"
)

// A PkgDecoder provides methods for decoding a package's Unified IR
// export data.
type PkgDecoder struct {
	// version is the file format version.
	version Version

	// sync indicates whether the file uses sync markers.
	sync bool

	// pkgPath is the package path for the package to be decoded.
	//
	// TODO(mdempsky): Remove; unneeded since CL 391014.
	pkgPath string

	// elemData is the full data payload of the encoded package.
	// Elements are densely and contiguously packed together.
	//
	// The last 8 bytes of elemData are the package fingerprint.
	elemData string

	// elemEnds stores the byte-offset end positions of element
	// bitstreams within elemData.
	//
	// For example, element I's bitstream data starts at elemEnds[I-1]
	// (or 0, if I==0) and ends at elemEnds[I].
	//
	// Note: elemEnds is indexed by absolute indices, not
	// section-relative indices.
	elemEnds []uint32

	// elemEndsEnds stores the index-offset end positions of relocation
	// sections within elemEnds.
	//
	// For example, section K's end positions start at elemEndsEnds[K-1]
	// (or 0, if K==0) and end at elemEndsEnds[K].
	elemEndsEnds [numRelocs]uint32

	scratchRelocEnt []RelocEnt
}

// PkgPath returns the package path for the package
//
// TODO(mdempsky): Remove; unneeded since CL 391014.
func (pr *PkgDecoder) PkgPath() string { return pr.pkgPath }

// SyncMarkers reports whether pr uses sync markers.
func (pr *PkgDecoder) SyncMarkers() bool { return pr.sync }

// NewPkgDecoder returns a PkgDecoder initialized to read the Unified
// IR export data from input. pkgPath is the package path for the
// compilation unit that produced the export data.
func NewPkgDecoder(pkgPath, input string) PkgDecoder {
	pr := PkgDecoder{
		pkgPath: pkgPath,
	}

	// TODO(mdempsky): Implement direct indexing of input string to
	// avoid copying the position information.

	r := strings.NewReader(input)

	var ver uint32
	assert(binary.Read(r, binary.LittleEndian, &ver) == nil)
	pr.version = Version(ver)

	if pr.version >= numVersions {
		panic(fmt.Errorf("cannot decode %q, export data version %d is greater than maximum supported version %d", pkgPath, pr.version, numVersions-1))
	}

	if pr.version.Has(Flags) {
		var flags uint32
		assert(binary.Read(r, binary.LittleEndian, &flags) == nil)
		pr.sync = flags&flagSyncMarkers != 0
	}

	assert(binary.Read(r, binary.LittleEndian, pr.elemEndsEnds[:]) == nil)

	pr.elemEnds = make([]uint32, pr.elemEndsEnds[len(pr.elemEndsEnds)-1])
	assert(binary.Read(r, binary.LittleEndian, pr.elemEnds[:]) == nil)

	pos, err := r.Seek(0, io.SeekCurrent)
	assert(err == nil)

	pr.elemData = input[pos:]

	const fingerprintSize = 8
	assert(len(pr.elemData)-fingerprintSize == int(pr.elemEnds[len(pr.elemEnds)-1]))

	return pr
}

// NumElems returns the number of elements in section k.
func (pr *PkgDecoder) NumElems(k RelocKind) int {
	count := int(pr.elemEndsEnds[k])
	if k > 0 {
		count -= int(pr.elemEndsEnds[k-1])
	}
	return count
}

// TotalElems returns the total number of elements across all sections.
func (pr *PkgDecoder) TotalElems() int {
	return len(pr.elemEnds)
}

// Fingerprint returns the package fingerprint.
func (pr *PkgDecoder) Fingerprint() [8]byte {
	var fp [8]byte
	copy(fp[:], pr.elemData[len(pr.elemData)-8:])
	return fp
}

// AbsIdx returns the absolute index for the given (section, index)
// pair.
func (pr *PkgDecoder) AbsIdx(k RelocKind, idx Index) int {
	absIdx := int(idx)
	if k > 0 {
		absIdx += int(pr.elemEndsEnds[k-1])
	}
	if absIdx >= int(pr.elemEndsEnds[k]) {
		panicf("%v:%v is out of bounds; %v", k, idx, pr.elemEndsEnds)
	}
	return absIdx
}

// DataIdx returns the raw element bitstream for the given (section,
// index) pair.
func (pr *PkgDecoder) DataIdx(k RelocKind, idx Index) string {
	absIdx := pr.AbsIdx(k, idx)

	var start uint32
	if absIdx > 0 {
		start = pr.elemEnds[absIdx-1]
	}
	end := pr.elemEnds[absIdx]

	return pr.elemData[start:end]
}

// StringIdx returns the string value for the given string index.
func (pr *PkgDecoder) StringIdx(idx Index) string {
	return pr.DataIdx(RelocString, idx)
}

// NewDecoder returns a Decoder for the given (section, index) pair,
// and decodes the given SyncMarker from the element bitstream.
func (pr *PkgDecoder) NewDecoder(k RelocKind, idx Index, marker SyncMarker) Decoder {
	r := pr.NewDecoderRaw(k, idx)
	r.Sync(marker)
	return r
}

// TempDecoder returns a Decoder for the given (section, index) pair,
// and decodes the given SyncMarker from the element bitstream.
// If possible the Decoder should be RetireDecoder'd when it is no longer
// needed, this will avoid heap allocations.
func (pr *PkgDecoder) TempDecoder(k RelocKind, idx Index, marker SyncMarker) Decoder {
	r := pr.TempDecoderRaw(k, idx)
	r.Sync(marker)
	return r
}

func (pr *PkgDecoder) RetireDecoder(d *Decoder) {
	pr.scratchRelocEnt = d.Relocs
	d.Relocs = nil
}

// NewDecoderRaw returns a Decoder for the given (section, index) pair.
//
// Most callers should use NewDecoder instead.
func (pr *PkgDecoder) NewDecoderRaw(k RelocKind, idx Index) Decoder {
	r := Decoder{
		common: pr,
		k:      k,
		Idx:    idx,
	}

	r.Data.Reset(pr.DataIdx(k, idx))
	r.Sync(SyncRelocs)
	r.Relocs = make([]RelocEnt, r.Len())
	for i := range r.Relocs {
		r.Sync(SyncReloc)
		r.Relocs[i] = RelocEnt{RelocKind(r.Len()), Index(r.Len())}
	}

	return r
}

func (pr *PkgDecoder) TempDecoderRaw(k RelocKind, idx Index) Decoder {
	r := Decoder{
		common: pr,
		k:      k,
		Idx:    idx,
	}

	r.Data.Reset(pr.DataIdx(k, idx))
	r.Sync(SyncRelocs)
	l := r.Len()
	if cap(pr.scratchRelocEnt) >= l {
		r.Relocs = pr.scratchRelocEnt[:l]
		pr.scratchRelocEnt = nil
	} else {
		r.Relocs = make([]RelocEnt, l)
	}
	for i := range r.Relocs {
		r.Sync(SyncReloc)
		r.Relocs[i] = RelocEnt{RelocKind(r.Len()), Index(r.Len())}
	}

	return r
}

// A Decoder provides methods for decoding an individual element's
// bitstream data.
type Decoder struct {
	common *PkgDecoder

	Relocs []RelocEnt
	Data   strings.Reader

	k   RelocKind
	Idx Index
}

func (r *Decoder) checkErr(err error) {
	if err != nil {
		panicf("unexpected decoding error: %w", err)
	}
}

func (r *Decoder) rawUvarint() uint64 {
	x, err := readUvarint(&r.Data)
	r.checkErr(err)
	return x
}

// readUvarint is a type-specialized copy of encoding/binary.ReadUvarint.
// This avoids the interface conversion and thus has better escape properties,
// which flows up the stack.
func readUvarint(r *strings.Reader) (uint64, error) {
	var x uint64
	var s uint
	for i := range binary.MaxVarintLen64 {
		b, err := r.ReadByte()
		if err != nil {
			if i > 0 && err == io.EOF {
				err = io.ErrUnexpectedEOF
			}
			return x, err
		}
		if b < 0x80 {
			if i == binary.MaxVarintLen64-1 && b > 1 {
				return x, overflow
			}
			return x | uint64(b)<<s, nil
		}
		x |= uint64(b&0x7f) << s
		s += 7
	}
	return x, overflow
}

var overflow = errors.New("pkgbits: readUvarint overflows a 64-bit integer")

func (r *Decoder) rawVarint() int64 {
	ux := r.rawUvarint()

	// Zig-zag decode.
	x := int64(ux >> 1)
	if ux&1 != 0 {
		x = ^x
	}
	return x
}

func (r *Decoder) rawReloc(k RelocKind, idx int) Index {
	e := r.Relocs[idx]
	assert(e.Kind == k)
	return e.Idx
}

// Sync decodes a sync marker from the element bitstream and asserts
// that it matches the expected marker.
//
// If r.common.sync is false, then Sync is a no-op.
func (r *Decoder) Sync(mWant SyncMarker) {
	if !r.common.sync {
		return
	}

	pos, _ := r.Data.Seek(0, io.SeekCurrent)
	mHave := SyncMarker(r.rawUvarint())
	writerPCs := make([]int, r.rawUvarint())
	for i := range writerPCs {
		writerPCs[i] = int(r.rawUvarint())
	}

	if mHave == mWant {
		return
	}

	// There's some tension here between printing:
	//
	// (1) full file paths that tools can recognize (e.g., so emacs
	//     hyperlinks the "file:line" text for easy navigation), or
	//
	// (2) short file paths that are easier for humans to read (e.g., by
	//     omitting redundant or irrelevant details, so it's easier to
	//     focus on the useful bits that remain).
	//
	// The current formatting favors the former, as it seems more
	// helpful in practice. But perhaps the formatting could be improved
	// to better address both concerns. For example, use relative file
	// paths if they would be shorter, or rewrite file paths to contain
	// "$GOROOT" (like objabi.AbsFile does) if tools can be taught how
	// to reliably expand that again.

	fmt.Printf("export data desync: package %q, section %v, index %v, offset %v\n", r.common.pkgPath, r.k, r.Idx, pos)

	fmt.Printf("\nfound %v, written at:\n", mHave)
	if len(writerPCs) == 0 {
		fmt.Printf("\t[stack trace unavailable; recompile package %q with -d=syncframes]\n", r.common.pkgPath)
	}
	for _, pc := range writerPCs {
		fmt.Printf("\t%s\n", r.common.StringIdx(r.rawReloc(RelocString, pc)))
	}

	fmt.Printf("\nexpected %v, reading at:\n", mWant)
	var readerPCs [32]uintptr // TODO(mdempsky): Dynamically size?
	n := runtime.Callers(2, readerPCs[:])
	for _, pc := range fmtFrames(readerPCs[:n]...) {
		fmt.Printf("\t%s\n", pc)
	}

	// We already printed a stack trace for the reader, so now we can
	// simply exit. Printing a second one with panic or base.Fatalf
	// would just be noise.
	os.Exit(1)
}

// Bool decodes and returns a bool value from the element bitstream.
func (r *Decoder) Bool() bool {
	r.Sync(SyncBool)
	x, err := r.Data.ReadByte()
	r.checkErr(err)
	assert(x < 2)
	return x != 0
}

// Int64 decodes and returns an int64 value from the element bitstream.
func (r *Decoder) Int64() int64 {
	r.Sync(SyncInt64)
	return r.rawVarint()
}

// Uint64 decodes and returns a uint64 value from the element bitstream.
func (r *Decoder) Uint64() uint64 {
	r.Sync(SyncUint64)
	return r.rawUvarint()
}

// Len decodes and returns a non-negative int value from the element bitstream.
func (r *Decoder) Len() int { x := r.Uint64(); v := int(x); assert(uint64(v) == x); return v }

// Int decodes and returns an int value from the element bitstream.
func (r *Decoder) Int() int { x := r.Int64(); v := int(x); assert(int64(v) == x); return v }

// Uint decodes and returns a uint value from the element bitstream.
func (r *Decoder) Uint() uint { x := r.Uint64(); v := uint(x); assert(uint64(v) == x); return v }

// Code decodes a Code value from the element bitstream and returns
// its ordinal value. It's the caller's responsibility to convert the
// result to an appropriate Code type.
//
// TODO(mdempsky): Ideally this method would have signature "Code[T
// Code] T" instead, but we don't allow generic methods and the
// compiler can't depend on generics yet anyway.
func (r *Decoder) Code(mark SyncMarker) int {
	r.Sync(mark)
	return r.Len()
}

// Reloc decodes a relocation of expected section k from the element
// bitstream and returns an index to the referenced element.
func (r *Decoder) Reloc(k RelocKind) Index {
	r.Sync(SyncUseReloc)
	return r.rawReloc(k, r.Len())
}

// String decodes and returns a string value from the element
// bitstream.
func (r *Decoder) String() string {
	r.Sync(SyncString)
	return r.common.StringIdx(r.Reloc(RelocString))
}

// Strings decodes and returns a variable-length slice of strings from
// the element bitstream.
func (r *Decoder) Strings() []string {
	res := make([]string, r.Len())
	for i := range res {
		res[i] = r.String()
	}
	return res
}

// Value decodes and returns a constant.Value from the element
// bitstream.
func (r *Decoder) Value() constant.Value {
	r.Sync(SyncValue)
	isComplex := r.Bool()
	val := r.scalar()
	if isComplex {
		val = constant.BinaryOp(val, token.ADD, constant.MakeImag(r.scalar()))
	}
	return val
}

func (r *Decoder) scalar() constant.Value {
	switch tag := CodeVal(r.Code(SyncVal)); tag {
	default:
		panic(fmt.Errorf("unexpected scalar tag: %v", tag))

	case ValBool:
		return constant.MakeBool(r.Bool())
	case ValString:
		return constant.MakeString(r.String())
	case ValInt64:
		return constant.MakeInt64(r.Int64())
	case ValBigInt:
		return constant.Make(r.bigInt())
	case ValBigRat:
		num := r.bigInt()
		denom := r.bigInt()
		return constant.Make(new(big.Rat).SetFrac(num, denom))
	case ValBigFloat:
		return constant.Make(r.bigFloat())
	}
}

func (r *Decoder) bigInt() *big.Int {
	v := new(big.Int).SetBytes([]byte(r.String()))
	if r.Bool() {
		v.Neg(v)
	}
	return v
}

func (r *Decoder) bigFloat() *big.Float {
	v := new(big.Float).SetPrec(512)
	assert(v.UnmarshalText([]byte(r.String())) == nil)
	return v
}

// @@@ Helpers

// TODO(mdempsky): These should probably be removed. I think they're a
// smell that the export data format is not yet quite right.

// PeekPkgPath returns the package path for the specified package
// index.
func (pr *PkgDecoder) PeekPkgPath(idx Index) string {
	var path string
	{
		r := pr.TempDecoder(RelocPkg, idx, SyncPkgDef)
		path = r.String()
		pr.RetireDecoder(&r)
	}
	if path == "" {
		path = pr.pkgPath
	}
	return path
}

// PeekObj returns the package path, object name, and CodeObj for the
// specified object index.
func (pr *PkgDecoder) PeekObj(idx Index) (string, string, CodeObj) {
	var ridx Index
	var name string
	var rcode int
	{
		r := pr.TempDecoder(RelocName, idx, SyncObject1)
		r.Sync(SyncSym)
		r.Sync(SyncPkg)
		ridx = r.Reloc(RelocPkg)
		name = r.String()
		rcode = r.Code(SyncCodeObj)
		pr.RetireDecoder(&r)
	}

	path := pr.PeekPkgPath(ridx)
	assert(name != "")

	tag := CodeObj(rcode)

	return path, name, tag
}

// Version reports the version of the bitstream.
func (w *Decoder) Version() Version { return w.common.version }


================================================
FILE: internal/pkgbits/doc.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package pkgbits implements low-level coding abstractions for
// Unified IR's export data format.
//
// At a low-level, a package is a collection of bitstream elements.
// Each element has a "kind" and a dense, non-negative index.
// Elements can be randomly accessed given their kind and index.
//
// Individual elements are sequences of variable-length values (e.g.,
// integers, booleans, strings, go/constant values, cross-references
// to other elements). Package pkgbits provides APIs for encoding and
// decoding these low-level values, but the details of mapping
// higher-level Go constructs into elements is left to higher-level
// abstractions.
//
// Elements may cross-reference each other with "relocations." For
// example, an element representing a pointer type has a relocation
// referring to the element type.
//
// Go constructs may be composed as a constellation of multiple
// elements. For example, a declared function may have one element to
// describe the object (e.g., its name, type, position), and a
// separate element to describe its function body. This allows readers
// some flexibility in efficiently seeking or re-reading data (e.g.,
// inlining requires re-reading the function body for each inlined
// call, without needing to re-read the object-level details).
//
// This is a copy of internal/pkgbits in the Go implementation.
package pkgbits


================================================
FILE: internal/pkgbits/encoder.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

import (
	"bytes"
	"crypto/md5"
	"encoding/binary"
	"go/constant"
	"io"
	"math/big"
	"runtime"
	"strings"
)

// A PkgEncoder provides methods for encoding a package's Unified IR
// export data.
type PkgEncoder struct {
	// version of the bitstream.
	version Version

	// elems holds the bitstream for previously encoded elements.
	elems [numRelocs][]string

	// stringsIdx maps previously encoded strings to their index within
	// the RelocString section, to allow deduplication. That is,
	// elems[RelocString][stringsIdx[s]] == s (if present).
	stringsIdx map[string]Index

	// syncFrames is the number of frames to write at each sync
	// marker. A negative value means sync markers are omitted.
	syncFrames int
}

// SyncMarkers reports whether pw uses sync markers.
func (pw *PkgEncoder) SyncMarkers() bool { return pw.syncFrames >= 0 }

// NewPkgEncoder returns an initialized PkgEncoder.
//
// syncFrames is the number of caller frames that should be serialized
// at Sync points. Serializing additional frames results in larger
// export data files, but can help diagnosing desync errors in
// higher-level Unified IR reader/writer code. If syncFrames is
// negative, then sync markers are omitted entirely.
func NewPkgEncoder(version Version, syncFrames int) PkgEncoder {
	return PkgEncoder{
		version:    version,
		stringsIdx: make(map[string]Index),
		syncFrames: syncFrames,
	}
}

// DumpTo writes the package's encoded data to out0 and returns the
// package fingerprint.
func (pw *PkgEncoder) DumpTo(out0 io.Writer) (fingerprint [8]byte) {
	h := md5.New()
	out := io.MultiWriter(out0, h)

	writeUint32 := func(x uint32) {
		assert(binary.Write(out, binary.LittleEndian, x) == nil)
	}

	writeUint32(uint32(pw.version))

	if pw.version.Has(Flags) {
		var flags uint32
		if pw.SyncMarkers() {
			flags |= flagSyncMarkers
		}
		writeUint32(flags)
	}

	// Write elemEndsEnds.
	var sum uint32
	for _, elems := range &pw.elems {
		sum += uint32(len(elems))
		writeUint32(sum)
	}

	// Write elemEnds.
	sum = 0
	for _, elems := range &pw.elems {
		for _, elem := range elems {
			sum += uint32(len(elem))
			writeUint32(sum)
		}
	}

	// Write elemData.
	for _, elems := range &pw.elems {
		for _, elem := range elems {
			_, err := io.WriteString(out, elem)
			assert(err == nil)
		}
	}

	// Write fingerprint.
	copy(fingerprint[:], h.Sum(nil))
	_, err := out0.Write(fingerprint[:])
	assert(err == nil)

	return
}

// StringIdx adds a string value to the strings section, if not
// already present, and returns its index.
func (pw *PkgEncoder) StringIdx(s string) Index {
	if idx, ok := pw.stringsIdx[s]; ok {
		assert(pw.elems[RelocString][idx] == s)
		return idx
	}

	idx := Index(len(pw.elems[RelocString]))
	pw.elems[RelocString] = append(pw.elems[RelocString], s)
	pw.stringsIdx[s] = idx
	return idx
}

// NewEncoder returns an Encoder for a new element within the given
// section, and encodes the given SyncMarker as the start of the
// element bitstream.
func (pw *PkgEncoder) NewEncoder(k RelocKind, marker SyncMarker) Encoder {
	e := pw.NewEncoderRaw(k)
	e.Sync(marker)
	return e
}

// NewEncoderRaw returns an Encoder for a new element within the given
// section.
//
// Most callers should use NewEncoder instead.
func (pw *PkgEncoder) NewEncoderRaw(k RelocKind) Encoder {
	idx := Index(len(pw.elems[k]))
	pw.elems[k] = append(pw.elems[k], "") // placeholder

	return Encoder{
		p:   pw,
		k:   k,
		Idx: idx,
	}
}

// An Encoder provides methods for encoding an individual element's
// bitstream data.
type Encoder struct {
	p *PkgEncoder

	Relocs   []RelocEnt
	RelocMap map[RelocEnt]uint32
	Data     bytes.Buffer // accumulated element bitstream data

	encodingRelocHeader bool

	k   RelocKind
	Idx Index // index within relocation section
}

// Flush finalizes the element's bitstream and returns its Index.
func (w *Encoder) Flush() Index {
	var sb strings.Builder

	// Backup the data so we write the relocations at the front.
	var tmp bytes.Buffer
	io.Copy(&tmp, &w.Data)

	// TODO(mdempsky): Consider writing these out separately so they're
	// easier to strip, along with function bodies, so that we can prune
	// down to just the data that's relevant to go/types.
	if w.encodingRelocHeader {
		panic("encodingRelocHeader already true; recursive flush?")
	}
	w.encodingRelocHeader = true
	w.Sync(SyncRelocs)
	w.Len(len(w.Relocs))
	for _, rEnt := range w.Relocs {
		w.Sync(SyncReloc)
		w.Len(int(rEnt.Kind))
		w.Len(int(rEnt.Idx))
	}

	io.Copy(&sb, &w.Data)
	io.Copy(&sb, &tmp)
	w.p.elems[w.k][w.Idx] = sb.String()

	return w.Idx
}

func (w *Encoder) checkErr(err error) {
	if err != nil {
		panicf("unexpected encoding error: %v", err)
	}
}

func (w *Encoder) rawUvarint(x uint64) {
	var buf [binary.MaxVarintLen64]byte
	n := binary.PutUvarint(buf[:], x)
	_, err := w.Data.Write(buf[:n])
	w.checkErr(err)
}

func (w *Encoder) rawVarint(x int64) {
	// Zig-zag encode.
	ux := uint64(x) << 1
	if x < 0 {
		ux = ^ux
	}

	w.rawUvarint(ux)
}

func (w *Encoder) rawReloc(r RelocKind, idx Index) int {
	e := RelocEnt{r, idx}
	if w.RelocMap != nil {
		if i, ok := w.RelocMap[e]; ok {
			return int(i)
		}
	} else {
		w.RelocMap = make(map[RelocEnt]uint32)
	}

	i := len(w.Relocs)
	w.RelocMap[e] = uint32(i)
	w.Relocs = append(w.Relocs, e)
	return i
}

func (w *Encoder) Sync(m SyncMarker) {
	if !w.p.SyncMarkers() {
		return
	}

	// Writing out stack frame string references requires working
	// relocations, but writing out the relocations themselves involves
	// sync markers. To prevent infinite recursion, we simply trim the
	// stack frame for sync markers within the relocation header.
	var frames []string
	if !w.encodingRelocHeader && w.p.syncFrames > 0 {
		pcs := make([]uintptr, w.p.syncFrames)
		n := runtime.Callers(2, pcs)
		frames = fmtFrames(pcs[:n]...)
	}

	// TODO(mdempsky): Save space by writing out stack frames as a
	// linked list so we can share common stack frames.
	w.rawUvarint(uint64(m))
	w.rawUvarint(uint64(len(frames)))
	for _, frame := range frames {
		w.rawUvarint(uint64(w.rawReloc(RelocString, w.p.StringIdx(frame))))
	}
}

// Bool encodes and writes a bool value into the element bitstream,
// and then returns the bool value.
//
// For simple, 2-alternative encodings, the idiomatic way to call Bool
// is something like:
//
//	if w.Bool(x != 0) {
//		// alternative #1
//	} else {
//		// alternative #2
//	}
//
// For multi-alternative encodings, use Code instead.
func (w *Encoder) Bool(b bool) bool {
	w.Sync(SyncBool)
	var x byte
	if b {
		x = 1
	}
	err := w.Data.WriteByte(x)
	w.checkErr(err)
	return b
}

// Int64 encodes and writes an int64 value into the element bitstream.
func (w *Encoder) Int64(x int64) {
	w.Sync(SyncInt64)
	w.rawVarint(x)
}

// Uint64 encodes and writes a uint64 value into the element bitstream.
func (w *Encoder) Uint64(x uint64) {
	w.Sync(SyncUint64)
	w.rawUvarint(x)
}

// Len encodes and writes a non-negative int value into the element bitstream.
func (w *Encoder) Len(x int) { assert(x >= 0); w.Uint64(uint64(x)) }

// Int encodes and writes an int value into the element bitstream.
func (w *Encoder) Int(x int) { w.Int64(int64(x)) }

// Uint encodes and writes a uint value into the element bitstream.
func (w *Encoder) Uint(x uint) { w.Uint64(uint64(x)) }

// Reloc encodes and writes a relocation for the given (section,
// index) pair into the element bitstream.
//
// Note: Only the index is formally written into the element
// bitstream, so bitstream decoders must know from context which
// section an encoded relocation refers to.
func (w *Encoder) Reloc(r RelocKind, idx Index) {
	w.Sync(SyncUseReloc)
	w.Len(w.rawReloc(r, idx))
}

// Code encodes and writes a Code value into the element bitstream.
func (w *Encoder) Code(c Code) {
	w.Sync(c.Marker())
	w.Len(c.Value())
}

// String encodes and writes a string value into the element
// bitstream.
//
// Internally, strings are deduplicated by adding them to the strings
// section (if not already present), and then writing a relocation
// into the element bitstream.
func (w *Encoder) String(s string) {
	w.StringRef(w.p.StringIdx(s))
}

// StringRef writes a reference to the given index, which must be a
// previously encoded string value.
func (w *Encoder) StringRef(idx Index) {
	w.Sync(SyncString)
	w.Reloc(RelocString, idx)
}

// Strings encodes and writes a variable-length slice of strings into
// the element bitstream.
func (w *Encoder) Strings(ss []string) {
	w.Len(len(ss))
	for _, s := range ss {
		w.String(s)
	}
}

// Value encodes and writes a constant.Value into the element
// bitstream.
func (w *Encoder) Value(val constant.Value) {
	w.Sync(SyncValue)
	if w.Bool(val.Kind() == constant.Complex) {
		w.scalar(constant.Real(val))
		w.scalar(constant.Imag(val))
	} else {
		w.scalar(val)
	}
}

func (w *Encoder) scalar(val constant.Value) {
	switch v := constant.Val(val).(type) {
	default:
		panicf("unhandled %v (%v)", val, val.Kind())
	case bool:
		w.Code(ValBool)
		w.Bool(v)
	case string:
		w.Code(ValString)
		w.String(v)
	case int64:
		w.Code(ValInt64)
		w.Int64(v)
	case *big.Int:
		w.Code(ValBigInt)
		w.bigInt(v)
	case *big.Rat:
		w.Code(ValBigRat)
		w.bigInt(v.Num())
		w.bigInt(v.Denom())
	case *big.Float:
		w.Code(ValBigFloat)
		w.bigFloat(v)
	}
}

func (w *Encoder) bigInt(v *big.Int) {
	b := v.Bytes()
	w.String(string(b)) // TODO: More efficient encoding.
	w.Bool(v.Sign() < 0)
}

func (w *Encoder) bigFloat(v *big.Float) {
	b := v.Append(nil, 'p', -1)
	w.String(string(b)) // TODO: More efficient encoding.
}

// Version reports the version of the bitstream.
func (w *Encoder) Version() Version { return w.p.version }


================================================
FILE: internal/pkgbits/flags.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

const (
	flagSyncMarkers = 1 << iota // file format contains sync markers
)


================================================
FILE: internal/pkgbits/pkgbits_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits_test

import (
	"strings"
	"testing"

	"golang.org/x/tools/internal/pkgbits"
)

func TestRoundTrip(t *testing.T) {
	for _, version := range []pkgbits.Version{
		pkgbits.V0,
		pkgbits.V1,
		pkgbits.V2,
	} {
		pw := pkgbits.NewPkgEncoder(version, -1)
		w := pw.NewEncoder(pkgbits.RelocMeta, pkgbits.SyncPublic)
		w.Flush()

		var b strings.Builder
		_ = pw.DumpTo(&b)
		input := b.String()

		pr := pkgbits.NewPkgDecoder("package_id", input)
		r := pr.NewDecoder(pkgbits.RelocMeta, pkgbits.PublicRootIdx, pkgbits.SyncPublic)

		if r.Version() != w.Version() {
			t.Errorf("Expected reader version %d to be the writer version %d", r.Version(), w.Version())
		}
	}
}

// Type checker to enforce that know V* have the constant values they must have.
var _ [0]bool = [pkgbits.V0]bool{}
var _ [1]bool = [pkgbits.V1]bool{}

func TestVersions(t *testing.T) {
	type vfpair struct {
		v pkgbits.Version
		f pkgbits.Field
	}

	// has field tests
	for _, c := range []vfpair{
		{pkgbits.V1, pkgbits.Flags},
		{pkgbits.V2, pkgbits.Flags},
		{pkgbits.V0, pkgbits.HasInit},
		{pkgbits.V1, pkgbits.HasInit},
		{pkgbits.V0, pkgbits.DerivedFuncInstance},
		{pkgbits.V1, pkgbits.DerivedFuncInstance},
		{pkgbits.V0, pkgbits.DerivedInfoNeeded},
		{pkgbits.V1, pkgbits.DerivedInfoNeeded},
		{pkgbits.V2, pkgbits.AliasTypeParamNames},
	} {
		if !c.v.Has(c.f) {
			t.Errorf("Expected version %v to have field %v", c.v, c.f)
		}
	}

	// does not have field tests
	for _, c := range []vfpair{
		{pkgbits.V0, pkgbits.Flags},
		{pkgbits.V2, pkgbits.HasInit},
		{pkgbits.V2, pkgbits.DerivedFuncInstance},
		{pkgbits.V2, pkgbits.DerivedInfoNeeded},
		{pkgbits.V0, pkgbits.AliasTypeParamNames},
		{pkgbits.V1, pkgbits.AliasTypeParamNames},
	} {
		if c.v.Has(c.f) {
			t.Errorf("Expected version %v to not have field %v", c.v, c.f)
		}
	}
}


================================================
FILE: internal/pkgbits/reloc.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

// A RelocKind indicates a particular section within a unified IR export.
type RelocKind int32

// An Index represents a bitstream element index within a particular
// section.
type Index int32

// A relocEnt (relocation entry) is an entry in an element's local
// reference table.
//
// TODO(mdempsky): Rename this too.
type RelocEnt struct {
	Kind RelocKind
	Idx  Index
}

// Reserved indices within the meta relocation section.
const (
	PublicRootIdx  Index = 0
	PrivateRootIdx Index = 1
)

const (
	RelocString RelocKind = iota
	RelocMeta
	RelocPosBase
	RelocPkg
	RelocName
	RelocType
	RelocObj
	RelocObjExt
	RelocObjDict
	RelocBody

	numRelocs = iota
)


================================================
FILE: internal/pkgbits/support.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

import "fmt"

func assert(b bool) {
	if !b {
		panic("assertion failed")
	}
}

func panicf(format string, args ...any) {
	panic(fmt.Errorf(format, args...))
}


================================================
FILE: internal/pkgbits/sync.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

import (
	"fmt"
	"runtime"
	"strings"
)

// fmtFrames formats a backtrace for reporting reader/writer desyncs.
func fmtFrames(pcs ...uintptr) []string {
	res := make([]string, 0, len(pcs))
	walkFrames(pcs, func(file string, line int, name string, offset uintptr) {
		// Trim package from function name. It's just redundant noise.
		name = strings.TrimPrefix(name, "cmd/compile/internal/noder.")

		res = append(res, fmt.Sprintf("%s:%v: %s +0x%v", file, line, name, offset))
	})
	return res
}

type frameVisitor func(file string, line int, name string, offset uintptr)

// walkFrames calls visit for each call frame represented by pcs.
//
// pcs should be a slice of PCs, as returned by runtime.Callers.
func walkFrames(pcs []uintptr, visit frameVisitor) {
	if len(pcs) == 0 {
		return
	}

	frames := runtime.CallersFrames(pcs)
	for {
		frame, more := frames.Next()
		visit(frame.File, frame.Line, frame.Function, frame.PC-frame.Entry)
		if !more {
			return
		}
	}
}

// SyncMarker is an enum type that represents markers that may be
// written to export data to ensure the reader and writer stay
// synchronized.
type SyncMarker int

//go:generate stringer -type=SyncMarker -trimprefix=Sync

const (
	_ SyncMarker = iota

	// Public markers (known to go/types importers).

	// Low-level coding markers.
	SyncEOF
	SyncBool
	SyncInt64
	SyncUint64
	SyncString
	SyncValue
	SyncVal
	SyncRelocs
	SyncReloc
	SyncUseReloc

	// Higher-level object and type markers.
	SyncPublic
	SyncPos
	SyncPosBase
	SyncObject
	SyncObject1
	SyncPkg
	SyncPkgDef
	SyncMethod
	SyncType
	SyncTypeIdx
	SyncTypeParamNames
	SyncSignature
	SyncParams
	SyncParam
	SyncCodeObj
	SyncSym
	SyncLocalIdent
	SyncSelector

	// Private markers (only known to cmd/compile).
	SyncPrivate

	SyncFuncExt
	SyncVarExt
	SyncTypeExt
	SyncPragma

	SyncExprList
	SyncExprs
	SyncExpr
	SyncExprType
	SyncAssign
	SyncOp
	SyncFuncLit
	SyncCompLit

	SyncDecl
	SyncFuncBody
	SyncOpenScope
	SyncCloseScope
	SyncCloseAnotherScope
	SyncDeclNames
	SyncDeclName

	SyncStmts
	SyncBlockStmt
	SyncIfStmt
	SyncForStmt
	SyncSwitchStmt
	SyncRangeStmt
	SyncCaseClause
	SyncCommClause
	SyncSelectStmt
	SyncDecls
	SyncLabeledStmt
	SyncUseObjLocal
	SyncAddLocal
	SyncLinkname
	SyncStmt1
	SyncStmtsEnd
	SyncLabel
	SyncOptLabel

	SyncMultiExpr
	SyncRType
	SyncConvRTTI
)


================================================
FILE: internal/pkgbits/syncmarker_string.go
================================================
// Code generated by "stringer -type=SyncMarker -trimprefix=Sync"; DO NOT EDIT.

package pkgbits

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[SyncEOF-1]
	_ = x[SyncBool-2]
	_ = x[SyncInt64-3]
	_ = x[SyncUint64-4]
	_ = x[SyncString-5]
	_ = x[SyncValue-6]
	_ = x[SyncVal-7]
	_ = x[SyncRelocs-8]
	_ = x[SyncReloc-9]
	_ = x[SyncUseReloc-10]
	_ = x[SyncPublic-11]
	_ = x[SyncPos-12]
	_ = x[SyncPosBase-13]
	_ = x[SyncObject-14]
	_ = x[SyncObject1-15]
	_ = x[SyncPkg-16]
	_ = x[SyncPkgDef-17]
	_ = x[SyncMethod-18]
	_ = x[SyncType-19]
	_ = x[SyncTypeIdx-20]
	_ = x[SyncTypeParamNames-21]
	_ = x[SyncSignature-22]
	_ = x[SyncParams-23]
	_ = x[SyncParam-24]
	_ = x[SyncCodeObj-25]
	_ = x[SyncSym-26]
	_ = x[SyncLocalIdent-27]
	_ = x[SyncSelector-28]
	_ = x[SyncPrivate-29]
	_ = x[SyncFuncExt-30]
	_ = x[SyncVarExt-31]
	_ = x[SyncTypeExt-32]
	_ = x[SyncPragma-33]
	_ = x[SyncExprList-34]
	_ = x[SyncExprs-35]
	_ = x[SyncExpr-36]
	_ = x[SyncExprType-37]
	_ = x[SyncAssign-38]
	_ = x[SyncOp-39]
	_ = x[SyncFuncLit-40]
	_ = x[SyncCompLit-41]
	_ = x[SyncDecl-42]
	_ = x[SyncFuncBody-43]
	_ = x[SyncOpenScope-44]
	_ = x[SyncCloseScope-45]
	_ = x[SyncCloseAnotherScope-46]
	_ = x[SyncDeclNames-47]
	_ = x[SyncDeclName-48]
	_ = x[SyncStmts-49]
	_ = x[SyncBlockStmt-50]
	_ = x[SyncIfStmt-51]
	_ = x[SyncForStmt-52]
	_ = x[SyncSwitchStmt-53]
	_ = x[SyncRangeStmt-54]
	_ = x[SyncCaseClause-55]
	_ = x[SyncCommClause-56]
	_ = x[SyncSelectStmt-57]
	_ = x[SyncDecls-58]
	_ = x[SyncLabeledStmt-59]
	_ = x[SyncUseObjLocal-60]
	_ = x[SyncAddLocal-61]
	_ = x[SyncLinkname-62]
	_ = x[SyncStmt1-63]
	_ = x[SyncStmtsEnd-64]
	_ = x[SyncLabel-65]
	_ = x[SyncOptLabel-66]
	_ = x[SyncMultiExpr-67]
	_ = x[SyncRType-68]
	_ = x[SyncConvRTTI-69]
}

const _SyncMarker_name = "EOFBoolInt64Uint64StringValueValRelocsRelocUseRelocPublicPosPosBaseObjectObject1PkgPkgDefMethodTypeTypeIdxTypeParamNamesSignatureParamsParamCodeObjSymLocalIdentSelectorPrivateFuncExtVarExtTypeExtPragmaExprListExprsExprExprTypeAssignOpFuncLitCompLitDeclFuncBodyOpenScopeCloseScopeCloseAnotherScopeDeclNamesDeclNameStmtsBlockStmtIfStmtForStmtSwitchStmtRangeStmtCaseClauseCommClauseSelectStmtDeclsLabeledStmtUseObjLocalAddLocalLinknameStmt1StmtsEndLabelOptLabelMultiExprRTypeConvRTTI"

var _SyncMarker_index = [...]uint16{0, 3, 7, 12, 18, 24, 29, 32, 38, 43, 51, 57, 60, 67, 73, 80, 83, 89, 95, 99, 106, 120, 129, 135, 140, 147, 150, 160, 168, 175, 182, 188, 195, 201, 209, 214, 218, 226, 232, 234, 241, 248, 252, 260, 269, 279, 296, 305, 313, 318, 327, 333, 340, 350, 359, 369, 379, 389, 394, 405, 416, 424, 432, 437, 445, 450, 458, 467, 472, 480}

func (i SyncMarker) String() string {
	i -= 1
	if i < 0 || i >= SyncMarker(len(_SyncMarker_index)-1) {
		return "SyncMarker(" + strconv.FormatInt(int64(i+1), 10) + ")"
	}
	return _SyncMarker_name[_SyncMarker_index[i]:_SyncMarker_index[i+1]]
}


================================================
FILE: internal/pkgbits/version.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pkgbits

// Version indicates a version of a unified IR bitstream.
// Each Version indicates the addition, removal, or change of
// new data in the bitstream.
//
// These are serialized to disk and the interpretation remains fixed.
type Version uint32

const (
	// V0: initial prototype.
	//
	// All data that is not assigned a Field is in version V0
	// and has not been deprecated.
	V0 Version = iota

	// V1: adds the Flags uint32 word
	V1

	// V2: removes unused legacy fields and supports type parameters for aliases.
	// - remove the legacy "has init" bool from the public root
	// - remove obj's "derived func instance" bool
	// - add a TypeParamNames field to ObjAlias
	// - remove derived info "needed" bool
	V2

	// V3: introduces a more compact format for composite literal element lists
	// - negative lengths indicate that (some) elements may have keys
	// - positive lengths indicate that no element has a key
	// - a negative struct field index indicates an embedded field
	V3

	numVersions = iota
)

// Field denotes a unit of data in the serialized unified IR bitstream.
// It is conceptually a like field in a structure.
//
// We only really need Fields when the data may or may not be present
// in a stream based on the Version of the bitstream.
//
// Unlike much of pkgbits, Fields are not serialized and
// can change values as needed.
type Field int

const (
	// Flags in a uint32 in the header of a bitstream
	// that is used to indicate whether optional features are enabled.
	Flags Field = iota

	// Deprecated: HasInit was a bool indicating whether a package
	// has any init functions.
	HasInit

	// Deprecated: DerivedFuncInstance was a bool indicating
	// whether an object was a function instance.
	DerivedFuncInstance

	// ObjAlias has a list of TypeParamNames.
	AliasTypeParamNames

	// Deprecated: DerivedInfoNeeded was a bool indicating
	// whether a type was a derived type.
	DerivedInfoNeeded

	// Composite literals use a more compact format for element lists.
	CompactCompLiterals

	numFields = iota
)

// introduced is the version a field was added.
var introduced = [numFields]Version{
	Flags:               V1,
	AliasTypeParamNames: V2,
	CompactCompLiterals: V3,
}

// removed is the version a field was removed in or 0 for fields
// that have not yet been deprecated.
// (So removed[f]-1 is the last version it is included in.)
var removed = [numFields]Version{
	HasInit:             V2,
	DerivedFuncInstance: V2,
	DerivedInfoNeeded:   V2,
}

// Has reports whether field f is present in a bitstream at version v.
func (v Version) Has(f Field) bool {
	return introduced[f] <= v && (v < removed[f] || removed[f] == V0)
}


================================================
FILE: internal/pprof/main.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The pprof command prints the total time in a pprof profile provided
// through the standard input.
package main

import (
	"compress/gzip"
	"fmt"
	"io"
	"log"
	"os"

	"golang.org/x/tools/internal/pprof"
)

func main() {
	rd, err := gzip.NewReader(os.Stdin)
	if err != nil {
		log.Fatal(err)
	}
	payload, err := io.ReadAll(rd)
	if err != nil {
		log.Fatal(err)
	}
	total, err := pprof.TotalTime(payload)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Println(total)
}


================================================
FILE: internal/pprof/pprof.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package pprof provides minimalistic routines for extracting
// information from profiles.
package pprof

import (
	"fmt"
	"time"
)

// TotalTime parses the profile data and returns the accumulated time.
// The input should not be gzipped.
func TotalTime(data []byte) (total time.Duration, err error) {
	defer func() {
		if x := recover(); x != nil {
			err = fmt.Errorf("error parsing pprof profile: %v", x)
		}
	}()
	decode(&total, data, msgProfile)
	return
}

// All errors are handled by panicking.
// Constants are copied below to avoid dependency on protobufs or pprof.

// protobuf wire types, from https://developers.google.com/protocol-buffers/docs/encoding
const (
	wireVarint = 0
	wireBytes  = 2
)

// pprof field numbers, from https://github.com/google/pprof/blob/master/proto/profile.proto
const (
	fldProfileSample = 2 // repeated Sample
	fldSampleValue   = 2 // repeated int64
)

// arbitrary numbering of message types
const (
	msgProfile = 0
	msgSample  = 1
)

func decode(total *time.Duration, data []byte, msg int) {
	for len(data) > 0 {
		// Read tag (wire type and field number).
		tag := varint(&data)

		// Read wire value (int or bytes).
		wire := tag & 7
		var ival uint64
		var sval []byte
		switch wire {
		case wireVarint:
			ival = varint(&data)

		case wireBytes:
			n := varint(&data)
			sval, data = data[:n], data[n:]

		default:
			panic(fmt.Sprintf("unexpected wire type: %d", wire))
		}

		// Process field of msg.
		fld := tag >> 3
		switch {
		case msg == msgProfile && fld == fldProfileSample:
			decode(total, sval, msgSample) // recursively decode Sample message

		case msg == msgSample, fld == fldSampleValue:
			*total += time.Duration(ival) // accumulate time
		}
	}
}

func varint(data *[]byte) (v uint64) {
	for i := 0; ; i++ {
		b := uint64((*data)[i])
		v += (b & 0x7f) << (7 * i)
		if b < 0x80 {
			*data = (*data)[i+1:]
			return v
		}
	}
}


================================================
FILE: internal/pprof/pprof_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package pprof_test

import (
	"bytes"
	"compress/gzip"
	"io"
	"log"
	"os"
	"testing"
	"time"

	"golang.org/x/tools/internal/pprof"
)

func TestTotalTime(t *testing.T) {
	// $ go tool pprof testdata/sample.pprof <&- 2>&1 | grep Total
	// Duration: 11.10s, Total samples = 27.59s (248.65%)
	const (
		filename = "testdata/sample.pprof"
		want     = time.Duration(27590003550)
	)

	profGz, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	rd, err := gzip.NewReader(bytes.NewReader(profGz))
	if err != nil {
		t.Fatal(err)
	}
	payload, err := io.ReadAll(rd)
	if err != nil {
		t.Fatal(err)
	}
	got, err := pprof.TotalTime(payload)
	if err != nil {
		log.Fatal(err)
	}
	if got != want {
		t.Fatalf("TotalTime(%q): got %v (%d), want %v (%d)", filename, got, got, want, want)
	}
}


================================================
FILE: internal/proxydir/proxydir.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package proxydir provides functions for writing module data to a directory
// in proxy format, so that it can be used as a module proxy by setting
// GOPROXY="file://<dir>".
package proxydir

import (
	"archive/zip"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
)

// WriteModuleVersion creates a directory in the proxy dir for a module.
func WriteModuleVersion(rootDir, module, ver string, files map[string][]byte) (rerr error) {
	dir := filepath.Join(rootDir, module, "@v")
	if err := os.MkdirAll(dir, 0755); err != nil {
		return err
	}

	// The go command checks for versions by looking at the "list" file.  Since
	// we are supporting multiple versions, create this file if it does not exist
	// or append the version number to the preexisting file.
	f, err := os.OpenFile(filepath.Join(dir, "list"), os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	defer checkClose("list file", f, &rerr)
	if _, err := f.WriteString(ver + "\n"); err != nil {
		return err
	}

	// Serve the go.mod file on the <version>.mod url, if it exists. Otherwise,
	// serve a stub.
	modContents, ok := files["go.mod"]
	if !ok {
		modContents = []byte("module " + module)
	}
	if err := os.WriteFile(filepath.Join(dir, ver+".mod"), modContents, 0644); err != nil {
		return err
	}

	// info file, just the bare bones.
	infoContents := fmt.Appendf(nil, `{"Version": "%v", "Time":"2017-12-14T13:08:43Z"}`, ver)
	if err := os.WriteFile(filepath.Join(dir, ver+".info"), infoContents, 0644); err != nil {
		return err
	}

	// zip of all the source files.
	f, err = os.OpenFile(filepath.Join(dir, ver+".zip"), os.O_CREATE|os.O_WRONLY, 0644)
	if err != nil {
		return err
	}
	defer checkClose("zip file", f, &rerr)
	z := zip.NewWriter(f)
	defer checkClose("zip writer", z, &rerr)
	for name, contents := range files {
		zf, err := z.Create(module + "@" + ver + "/" + name)
		if err != nil {
			return err
		}
		if _, err := zf.Write(contents); err != nil {
			return err
		}
	}

	return nil
}

func checkClose(name string, closer io.Closer, err *error) {
	if cerr := closer.Close(); cerr != nil && *err == nil {
		*err = fmt.Errorf("closing %s: %v", name, cerr)
	}
}

// ToURL returns the file uri for a proxy directory.
func ToURL(dir string) string {
	// file URLs on Windows must start with file:///. See golang.org/issue/6027.
	path := filepath.ToSlash(dir)
	if !strings.HasPrefix(path, "/") {
		path = "/" + path
	}
	return "file://" + path
}


================================================
FILE: internal/proxydir/proxydir_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package proxydir

import (
	"archive/zip"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

func TestWriteModuleVersion(t *testing.T) {
	tests := []struct {
		modulePath, version string
		files               map[string][]byte
	}{
		{
			modulePath: "mod.test/module",
			version:    "v1.2.3",
			files: map[string][]byte{
				"go.mod":   []byte("module mod.com\n\ngo 1.12"),
				"const.go": []byte("package module\n\nconst Answer = 42"),
			},
		},
		{
			modulePath: "mod.test/module",
			version:    "v1.2.4",
			files: map[string][]byte{
				"go.mod":   []byte("module mod.com\n\ngo 1.12"),
				"const.go": []byte("package module\n\nconst Answer = 43"),
			},
		},
		{
			modulePath: "mod.test/nogomod",
			version:    "v0.9.0",
			files: map[string][]byte{
				"const.go": []byte("package module\n\nconst Other = \"Other\""),
			},
		},
	}
	dir, err := os.MkdirTemp("", "proxydirtest-")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(dir)
	for _, test := range tests {
		// Since we later assert on the contents of /list, don't use subtests.
		if err := WriteModuleVersion(dir, test.modulePath, test.version, test.files); err != nil {
			t.Fatal(err)
		}
		rootDir := filepath.Join(dir, filepath.FromSlash(test.modulePath), "@v")
		gomod, err := os.ReadFile(filepath.Join(rootDir, test.version+".mod"))
		if err != nil {
			t.Fatal(err)
		}
		wantMod, ok := test.files["go.mod"]
		if !ok {
			wantMod = []byte("module " + test.modulePath)
		}
		if got, want := string(gomod), string(wantMod); got != want {
			t.Errorf("reading %s/@v/%s.mod: got %q, want %q", test.modulePath, test.version, got, want)
		}
		zr, err := zip.OpenReader(filepath.Join(rootDir, test.version+".zip"))
		if err != nil {
			t.Fatal(err)
		}
		defer zr.Close()

		for _, zf := range zr.File {
			r, err := zf.Open()
			if err != nil {
				t.Fatal(err)
			}
			defer r.Close()
			content, err := io.ReadAll(r)
			if err != nil {
				t.Fatal(err)
			}
			name := strings.TrimPrefix(zf.Name, fmt.Sprintf("%s@%s/", test.modulePath, test.version))
			if got, want := string(content), string(test.files[name]); got != want {
				t.Errorf("unzipping %q: got %q, want %q", zf.Name, got, want)
			}
			delete(test.files, name)
		}
		for name := range test.files {
			t.Errorf("file %q not present in the module zip", name)
		}
	}

	lists := []struct {
		modulePath, want string
	}{
		{"mod.test/module", "v1.2.3\nv1.2.4\n"},
		{"mod.test/nogomod", "v0.9.0\n"},
	}

	for _, test := range lists {
		fp := filepath.Join(dir, filepath.FromSlash(test.modulePath), "@v", "list")
		list, err := os.ReadFile(fp)
		if err != nil {
			t.Fatal(err)
		}
		if got := string(list); got != test.want {
			t.Errorf("%q/@v/list: got %q, want %q", test.modulePath, got, test.want)
		}
	}
}


================================================
FILE: internal/refactor/delete.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package refactor

// This file defines operations for computing deletion edits.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"slices"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

// DeleteVar returns edits to delete the declaration of a variable or
// constant whose defining identifier is curId.
//
// It handles variants including:
// - GenDecl > ValueSpec versus AssignStmt;
// - RHS expression has effects, or not;
// - entire statement/declaration may be eliminated;
// and removes associated comments.
//
// If it cannot make the necessary edits, such as for a function
// parameter or result, it returns nil.
func DeleteVar(tokFile *token.File, info *types.Info, curId inspector.Cursor) []Edit {
	switch curId.ParentEdgeKind() {
	case edge.ValueSpec_Names:
		return deleteVarFromValueSpec(tokFile, info, curId)

	case edge.AssignStmt_Lhs:
		return deleteVarFromAssignStmt(tokFile, info, curId)
	}

	// e.g. function receiver, parameter, or result,
	// or "switch v := expr.(T) {}" (which has no object).
	return nil
}

// deleteVarFromValueSpec returns edits to delete the declaration of a
// variable or constant within a ValueSpec.
//
// Precondition: curId is Ident beneath ValueSpec.Names beneath GenDecl.
//
// See also [deleteVarFromAssignStmt], which has parallel structure.
func deleteVarFromValueSpec(tokFile *token.File, info *types.Info, curIdent inspector.Cursor) []Edit {
	var (
		id      = curIdent.Node().(*ast.Ident)
		curSpec = curIdent.Parent()
		spec    = curSpec.Node().(*ast.ValueSpec)
	)

	declaresOtherNames := slices.ContainsFunc(spec.Names, func(name *ast.Ident) bool {
		return name != id && name.Name != "_"
	})
	noRHSEffects := !slices.ContainsFunc(spec.Values, func(rhs ast.Expr) bool {
		return !typesinternal.NoEffects(info, rhs)
	})
	if !declaresOtherNames && noRHSEffects {
		// The spec is no longer needed, either to declare
		// other variables, or for its side effects.
		return DeleteSpec(tokFile, curSpec)
	}

	// The spec is still needed, either for
	// at least one LHS, or for effects on RHS.
	// Blank out or delete just one LHS.

	index := curIdent.ParentEdgeIndex() // index of LHS within ValueSpec.Names

	// If there is no RHS, we can delete the LHS.
	if len(spec.Values) == 0 {
		var pos, end token.Pos
		if index == len(spec.Names)-1 {
			// Delete final name.
			//
			// var _, lhs1 T
			//      ------
			pos = spec.Names[index-1].End()
			end = spec.Names[index].End()
		} else {
			// Delete non-final name.
			//
			// var lhs0, _ T
			//     ------
			pos = spec.Names[index].Pos()
			end = spec.Names[index+1].Pos()
		}
		return []Edit{{
			Pos: pos,
			End: end,
		}}
	}

	// If the assignment is n:n and the RHS has no effects,
	// we can delete the LHS and its corresponding RHS.
	if len(spec.Names) == len(spec.Values) &&
		typesinternal.NoEffects(info, spec.Values[index]) {

		if index == len(spec.Names)-1 {
			// Delete final items.
			//
			// var _, lhs1 = rhs0, rhs1
			//      ------       ------
			return []Edit{
				{
					Pos: spec.Names[index-1].End(),
					End: spec.Names[index].End(),
				},
				{
					Pos: spec.Values[index-1].End(),
					End: spec.Values[index].End(),
				},
			}
		} else {
			// Delete non-final items.
			//
			// var lhs0, _ = rhs0, rhs1
			//     ------    ------
			return []Edit{
				{
					Pos: spec.Names[index].Pos(),
					End: spec.Names[index+1].Pos(),
				},
				{
					Pos: spec.Values[index].Pos(),
					End: spec.Values[index+1].Pos(),
				},
			}
		}
	}

	// We cannot delete the RHS.
	// Blank out the LHS.
	return []Edit{{
		Pos:     id.Pos(),
		End:     id.End(),
		NewText: []byte("_"),
	}}
}

// Precondition: curId is Ident beneath AssignStmt.Lhs.
//
// See also [deleteVarFromValueSpec], which has parallel structure.
func deleteVarFromAssignStmt(tokFile *token.File, info *types.Info, curIdent inspector.Cursor) []Edit {
	var (
		id      = curIdent.Node().(*ast.Ident)
		curStmt = curIdent.Parent()
		assign  = curStmt.Node().(*ast.AssignStmt)
	)

	declaresOtherNames := slices.ContainsFunc(assign.Lhs, func(lhs ast.Expr) bool {
		lhsId, ok := lhs.(*ast.Ident)
		return ok && lhsId != id && lhsId.Name != "_"
	})
	noRHSEffects := !slices.ContainsFunc(assign.Rhs, func(rhs ast.Expr) bool {
		return !typesinternal.NoEffects(info, rhs)
	})
	if !declaresOtherNames && noRHSEffects {
		// The assignment is no longer needed, either to
		// declare other variables, or for its side effects.
		if edits := DeleteStmt(tokFile, curStmt); edits != nil {
			return edits
		}
		// Statement could not not be deleted in this context.
		// Fall back to conservative deletion.
	}

	// The assign is still needed, either for
	// at least one LHS, or for effects on RHS,
	// or because it cannot deleted because of its context.
	// Blank out or delete just one LHS.

	// If the assignment is 1:1 and the RHS has no effects,
	// we can delete the LHS and its corresponding RHS.
	index := curIdent.ParentEdgeIndex()
	if len(assign.Lhs) > 1 &&
		len(assign.Lhs) == len(assign.Rhs) &&
		typesinternal.NoEffects(info, assign.Rhs[index]) {

		if index == len(assign.Lhs)-1 {
			// Delete final items.
			//
			// _, lhs1 := rhs0, rhs1
			//  ------        ------
			return []Edit{
				{
					Pos: assign.Lhs[index-1].End(),
					End: assign.Lhs[index].End(),
				},
				{
					Pos: assign.Rhs[index-1].End(),
					End: assign.Rhs[index].End(),
				},
			}
		} else {
			// Delete non-final items.
			//
			// lhs0, _ := rhs0, rhs1
			// ------     ------
			return []Edit{
				{
					Pos: assign.Lhs[index].Pos(),
					End: assign.Lhs[index+1].Pos(),
				},
				{
					Pos: assign.Rhs[index].Pos(),
					End: assign.Rhs[index+1].Pos(),
				},
			}
		}
	}

	// We cannot delete the RHS.
	// Blank out the LHS.
	edits := []Edit{{
		Pos:     id.Pos(),
		End:     id.End(),
		NewText: []byte("_"),
	}}

	// If this eliminates the final variable declared by
	// an := statement, we need to turn it into an =
	// assignment to avoid a "no new variables on left
	// side of :=" error.
	if !declaresOtherNames {
		edits = append(edits, Edit{
			Pos:     assign.TokPos,
			End:     assign.TokPos + token.Pos(len(":=")),
			NewText: []byte("="),
		})
	}

	return edits
}

// DeleteSpec returns edits to delete the {Type,Value}Spec identified by curSpec.
//
// TODO(adonovan): add test suite. Test for consts as well.
func DeleteSpec(tokFile *token.File, curSpec inspector.Cursor) []Edit {
	var (
		spec    = curSpec.Node().(ast.Spec)
		curDecl = curSpec.Parent()
		decl    = curDecl.Node().(*ast.GenDecl)
	)

	// If it is the sole spec in the decl,
	// delete the entire decl.
	if len(decl.Specs) == 1 {
		return DeleteDecl(tokFile, curDecl)
	}

	// Delete the spec and its comments.
	index := curSpec.ParentEdgeIndex() // index of ValueSpec within GenDecl.Specs
	pos, end := spec.Pos(), spec.End()
	if doc := astutil.DocComment(spec); doc != nil {
		pos = doc.Pos() // leading comment
	}
	if index == len(decl.Specs)-1 {
		// Delete final spec.
		if c := eolComment(spec); c != nil {
			//  var (v int // comment \n)
			end = c.End()
		}
	} else {
		// Delete non-final spec.
		//   var ( a T; b T )
		//         -----
		end = decl.Specs[index+1].Pos()
	}
	return []Edit{{
		Pos: pos,
		End: end,
	}}
}

// DeleteDecl returns edits to delete the ast.Decl identified by curDecl.
//
// TODO(adonovan): add test suite.
func DeleteDecl(tokFile *token.File, curDecl inspector.Cursor) []Edit {
	decl := curDecl.Node().(ast.Decl)

	ek := curDecl.ParentEdgeKind()
	switch ek {
	case edge.DeclStmt_Decl:
		return DeleteStmt(tokFile, curDecl.Parent())

	case edge.File_Decls:
		pos, end := decl.Pos(), decl.End()
		if doc := astutil.DocComment(decl); doc != nil {
			pos = doc.Pos()
		}

		// Delete free-floating comments on same line as rparen.
		//    var (...) // comment
		var (
			file        = curDecl.Parent().Node().(*ast.File)
			lineOf      = tokFile.Line
			declEndLine = lineOf(decl.End())
		)
		for _, cg := range file.Comments {
			for _, c := range cg.List {
				if c.Pos() < end {
					continue // too early
				}
				commentEndLine := lineOf(c.End())
				if commentEndLine > declEndLine {
					break // too late
				} else if lineOf(c.Pos()) == declEndLine && commentEndLine == declEndLine {
					end = c.End()
				}
			}
		}

		return []Edit{{
			Pos: pos,
			End: end,
		}}

	default:
		panic(fmt.Sprintf("Decl parent is %v, want DeclStmt or File", ek))
	}
}

// find leftmost Pos bigger than start and rightmost less than end
func filterPos(nds []*ast.Comment, start, end token.Pos) (token.Pos, token.Pos, bool) {
	l, r := end, token.NoPos
	ok := false
	for _, n := range nds {
		if n.Pos() > start && n.Pos() < l {
			l = n.Pos()
			ok = true
		}
		if n.End() <= end && n.End() > r {
			r = n.End()
			ok = true
		}
	}
	return l, r, ok
}

// DeleteStmt returns the edits to remove the [ast.Stmt] identified by
// curStmt if it recognizes the context. It returns nil otherwise.
// TODO(pjw, adonovan): it should not return nil, it should return an error
//
// DeleteStmt is called with just the AST so it has trouble deciding if
// a comment is associated with the statement to be deleted. For instance,
//
//	for /*A*/ init()/*B*/;/*C/cond()/*D/;/*E*/post() /*F*/ { /*G*/}
//
// comment B and C are indistinguishable, as are D and E. That is, as the
// AST does not say where the semicolons are, B and C could go either
// with the init() or the cond(), so cannot be removed safely. The same
// is true for D, E, and the post(). (And there are other similar cases.)
// But the other comments can be removed as they are unambiguously
// associated with the statement being deleted. In particular,
// it removes whole lines like
//
//	stmt // comment
func DeleteStmt(file *token.File, curStmt inspector.Cursor) []Edit {
	// if the stmt is on a line by itself, or a range of lines, delete the whole thing
	// including comments. Except for the heads of switches, type
	// switches, and for-statements that's the usual case. Complexity occurs where
	// there are multiple statements on the same line, and adjacent comments.

	// In that case we remove some adjacent comments:
	// In me()/*A*/;b(), comment A cannot be removed, because the ast
	// is indistinguishable from me();/*A*/b()
	// and the same for cases like switch me()/*A*/; x.(type) {

	// this would be more precise with the file contents, or if the ast
	// contained the location of semicolons
	var (
		stmt          = curStmt.Node().(ast.Stmt)
		tokFile       = file
		lineOf        = tokFile.Line
		stmtStartLine = lineOf(stmt.Pos())
		stmtEndLine   = lineOf(stmt.End())

		leftSyntax, rightSyntax     token.Pos      // pieces of parent node on stmt{Start,End}Line
		leftComments, rightComments []*ast.Comment // comments before/after stmt on the same line
	)

	// remember the Pos that are on the same line as stmt
	use := func(left, right token.Pos) {
		if lineOf(left) == stmtStartLine {
			leftSyntax = left
		}
		if lineOf(right) == stmtEndLine {
			rightSyntax = right
		}
	}

	// find the comments, if any, on the same line
Big:
	for _, cg := range astutil.EnclosingFile(curStmt).Comments {
		for _, co := range cg.List {
			if lineOf(co.End()) < stmtStartLine {
				continue
			} else if lineOf(co.Pos()) > stmtEndLine {
				break Big // no more are possible
			}
			if lineOf(co.End()) == stmtStartLine && co.End() <= stmt.Pos() {
				// comment is before the statement
				leftComments = append(leftComments, co)
			} else if lineOf(co.Pos()) == stmtEndLine && co.Pos() >= stmt.End() {
				// comment is after the statement
				rightComments = append(rightComments, co)
			}
		}
	}

	// find any other syntax on the same line
	var (
		leftStmt, rightStmt token.Pos // end/start positions of sibling statements in a []Stmt list
		inStmtList          = false
		curParent           = curStmt.Parent()
	)
	switch parent := curParent.Node().(type) {
	case *ast.BlockStmt:
		use(parent.Lbrace, parent.Rbrace)
		inStmtList = true
	case *ast.CaseClause:
		use(parent.Colon, curStmt.Parent().Parent().Node().(*ast.BlockStmt).Rbrace)
		inStmtList = true
	case *ast.CommClause:
		if parent.Comm == stmt {
			return nil // maybe the user meant to remove the entire CommClause?
		}
		use(parent.Colon, curStmt.Parent().Parent().Node().(*ast.BlockStmt).Rbrace)
		inStmtList = true
	case *ast.ForStmt:
		use(parent.For, parent.Body.Lbrace)
		// special handling, as init;cond;post BlockStmt is not a statment list
		if parent.Init != nil && parent.Cond != nil && stmt == parent.Init && lineOf(parent.Cond.Pos()) == lineOf(stmt.End()) {
			rightStmt = parent.Cond.Pos()
		} else if parent.Post != nil && parent.Cond != nil && stmt == parent.Post && lineOf(parent.Cond.End()) == lineOf(stmt.Pos()) {
			leftStmt = parent.Cond.End()
		}
	case *ast.IfStmt:
		switch stmt {
		case parent.Init:
			use(parent.If, parent.Body.Lbrace)
		case parent.Else:
			// stmt is the {...} in "if cond {} else {...}" and removing
			// it would require removing the 'else' keyword, but the ast
			// does not contain its position.
			return nil
		}
	case *ast.SwitchStmt:
		use(parent.Switch, parent.Body.Lbrace)
	case *ast.TypeSwitchStmt:
		if stmt == parent.Assign {
			return nil // don't remove .(type)
		}
		use(parent.Switch, parent.Body.Lbrace)
	default:
		return nil // not one of ours
	}

	if inStmtList {
		// find the siblings, if any, on the same line
		if prev, found := curStmt.PrevSibling(); found && lineOf(prev.Node().End()) == stmtStartLine {
			if _, ok := prev.Node().(ast.Stmt); ok {
				leftStmt = prev.Node().End() // preceding statement ends on same line
			}
		}
		if next, found := curStmt.NextSibling(); found && lineOf(next.Node().Pos()) == stmtEndLine {
			rightStmt = next.Node().Pos() // following statement begins on same line
		}
	}

	// compute the left and right limits of the edit
	var leftEdit, rightEdit token.Pos
	if leftStmt.IsValid() {
		leftEdit = stmt.Pos() // can't remove preceding comments: a()/*A*/; me()
	} else if leftSyntax.IsValid() {
		// remove intervening leftComments
		if a, _, ok := filterPos(leftComments, leftSyntax, stmt.Pos()); ok {
			leftEdit = a
		} else {
			leftEdit = stmt.Pos()
		}
	} else { // remove whole line
		for leftEdit = stmt.Pos(); lineOf(leftEdit) == stmtStartLine; leftEdit-- {
		}
		if leftEdit < stmt.Pos() {
			leftEdit++ // beginning of line
		}
	}
	if rightStmt.IsValid() {
		rightEdit = stmt.End() // can't remove following comments
	} else if rightSyntax.IsValid() {
		// remove intervening rightComments
		if _, b, ok := filterPos(rightComments, stmt.End(), rightSyntax); ok {
			rightEdit = b
		} else {
			rightEdit = stmt.End()
		}
	} else { // remove whole line
		fend := token.Pos(file.Base()) + token.Pos(file.Size())
		for rightEdit = stmt.End(); fend >= rightEdit && lineOf(rightEdit) == stmtEndLine; rightEdit++ {
		}
		// don't remove \n if there was other stuff earlier
		if leftSyntax.IsValid() || leftStmt.IsValid() {
			rightEdit--
		}
	}

	return []Edit{{Pos: leftEdit, End: rightEdit}}
}

// DeleteUnusedVars computes the edits required to delete the
// declarations of any local variables whose last uses are in the
// curDelend subtree, which is about to be deleted.
func DeleteUnusedVars(index *typeindex.Index, info *types.Info, tokFile *token.File, curDelend inspector.Cursor) []Edit {
	// TODO(adonovan): we might want to generalize this by
	// splitting the two phases below, so that we can gather
	// across a whole sequence of deletions then finally compute the
	// set of variables that are no longer wanted.

	// Count number of deletions of each var.
	delcount := make(map[*types.Var]int)
	for curId := range curDelend.Preorder((*ast.Ident)(nil)) {
		id := curId.Node().(*ast.Ident)
		if v, ok := info.Uses[id].(*types.Var); ok &&
			typesinternal.GetVarKind(v) == typesinternal.LocalVar { // always false before go1.25
			delcount[v]++
		}
	}

	// Delete declaration of each var that became unused.
	var edits []Edit
	for v, count := range delcount {
		if len(slices.Collect(index.Uses(v))) == count {
			if curDefId, ok := index.Def(v); ok {
				edits = append(edits, DeleteVar(tokFile, info, curDefId)...)
			}
		}
	}
	return edits
}

func eolComment(n ast.Node) *ast.CommentGroup {
	// TODO(adonovan): support:
	//    func f() {...} // comment
	switch n := n.(type) {
	case *ast.GenDecl:
		if !n.TokPos.IsValid() && len(n.Specs) == 1 {
			return eolComment(n.Specs[0])
		}
	case *ast.ValueSpec:
		return n.Comment
	case *ast.TypeSpec:
		return n.Comment
	}
	return nil
}


================================================
FILE: internal/refactor/delete_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package refactor_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"slices"
	"testing"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/refactor"
)

func TestDeleteStmt(t *testing.T) {
	type testCase struct {
		in    string
		which int // count of ast.Stmt in ast.Inspect traversal to remove
		want  string
		name  string // should contain exactly one of [block,switch,case,comm,for,type]
	}
	tests := []testCase{
		{
			in:    "package p; func f() {/*a*/x := 12/*b*/}",
			which: 1,
			want:  "package p; func f() {}",
			name:  "var0",
		},
		{
			in:    "package p; func f() {\n/*a*/x := 12 //foo\n//keep\n}",
			which: 1,
			want:  "package p; func f() {\n//keep\n}",
			name:  "var1",
		},
		{ // for code coverage
			in:    "package p; func f() {/*a*/x:=12/*b*/; y:=11}",
			which: 1,
			want:  "package p; func f() {/*b*/; y:=11}",
			name:  "var2",
		},
		{ // do nothing when asked to remove a function body
			in:    "package p; func f() {  }",
			which: 0,
			want:  "package p; func f() {  }",
			name:  "block0",
		},
		{
			in:    "package p; func f() { abcd()}",
			which: 1,
			want:  "package p; func f() { }",
			name:  "block1",
		},
		{ // keep white space
			in:    "package p; func f() { a() }",
			which: 1,
			want:  "package p; func f() {  }",
			name:  "block2",
		},
		{ // keep semicolon
			in:    "package p; func f() { a();}",
			which: 1,
			want:  "package p; func f() { ;}",
			name:  "block3",
		},
		{ // remove whole line
			in:    "package p; func f() {\n a() \n\n}",
			which: 1,
			want:  "package p; func f() {\n\n}",
			name:  "block4",
		},
		{ // preserve whitespace and remove comment
			in:    "package p; func f() { a()// comment\n}",
			which: 1,
			want:  "package p; func f() { \n}",
			name:  "block5",
		},
		{ // preserve whitespace, remove preceding comment
			in:    "package p; func f() { /*c*/a() \n}",
			which: 1,
			want:  "package p; func f() { \n}",
			name:  "block6",
		},
		{
			in:    "package p; func f() { a();b();}",
			which: 2,
			want:  "package p; func f() { a();;}",
			name:  "block7",
		},
		{ // remove whole line
			in:    "package p; func f() {\n\ta()\n\tb()\n}",
			which: 2,
			want:  "package p; func f() {\n\ta()\n}",
			name:  "block8",
		},
		{ // remove whole line
			in:    "package p; func f() {\n\ta()\n\tb()\n\tc()\n}",
			which: 2,
			want:  "package p; func f() {\n\ta()\n\tc()\n}",
			name:  "block9",
		},
		{ // remove expression statement
			in:    "package p\nfunc f() {a()+b()}",
			which: 1,
			want:  "package p\nfunc f() {}",
			name:  "block10",
		},
		{ // even in parentheses
			in:    "package p\nfunc f() {(a()+b())}",
			which: 1,
			want:  "package p\nfunc f() {}",
			name:  "block11",
		},
		{ // should it also remove the semicolon? No, can't find it.
			in:    "package p; func f() { switch a(); b() {}}",
			which: 2, // 0 is the func body, 1 is the switch statement
			want:  "package p; func f() { switch ; b() {}}",
			name:  "switch0",
		},
		{ // remove preceding comment too
			in:    "package p; func f() { switch /*c*/a(); {}}",
			which: 2, // 0 is the func body, 1 is the switch statement
			want:  "package p; func f() { switch ; {}}",
			name:  "switch1",
		},
		{ // remove subsequent comment too
			in:    "package p; func f() { switch a()/*c*/; {}}",
			which: 2, // 0 is the func body, 1 is the switch statement
			want:  "package p; func f() { switch ; {}}",
			name:  "switch2",
		},
		{ // statement inside a case
			in:    "package p; func f() { select {default: a()}}",
			which: 4, // 0 is the func body, 1 is the select statement, 2 is its body, 3 is the comm clause
			want:  "package p; func f() { select {default: }}",
			name:  "comm0",
		},
		{ // statement in comm clause
			in:    "package p; func f(x chan any) { select {case x <- a: a(x)}}",
			which: 5, // 0 is the func body, 1 is the select statement, 2 is its body, 3 is the comm clause
			want:  "package p; func f(x chan any) { select {case x <- a: }}",
			name:  "comm1",
		},
		{ // don't remove whole clause
			in:    "package p; func f(x chan any) { select {case x <- a: a(x)}}",
			which: 4, // 0 is the func body, 1 is the select statement, 2 is its body, 3 is the comm clause
			want:  "package p; func f(x chan any) { select {case x <- a: a(x)}}",
			name:  "comm2",
		},
		{
			in:    "package p; func f() { switch {default: a()}}",
			which: 4, // 0 is the func body, 1 is the select statement, 2 is its body
			want:  "package p; func f() { switch {default: }}",
			name:  "case0",
		},
		{
			in:    "package p; func f() { switch {case 3: /*A*/ a() /*B*/}}",
			which: 4, // 0 is the func body, 1 is the select statement, 2 is its body
			want:  "package p; func f() { switch {case 3: }}",
			name:  "case1",
		},
		{ // init in for statement
			in:    "package p; func f() {for /*a*/ a();;b() {}}",
			which: 2,
			want:  "package p; func f() {for ;;b() {}}",
			name:  "for0",
		},
		{ // step in for statement
			in:    "package p; func f() {for a();c();b() /*B*/ {}}",
			which: 3,
			want:  "package p; func f() {for a();c(); {}}",
			name:  "for1",
		},
		{ // one of two func calls on. line
			in:    "package p; func f() {for\na();c()\nb() {}}",
			which: 2,
			want:  "package p; func f() {for\n;c()\nb() {}}",
			name:  "for2",
		},
		{ // step in for, with strange \n
			in:    "package p; func f() {for a();\nc();b() {}}",
			which: 3,
			want:  "package p; func f() {for a();\nc(); {}}",
			name:  "for3",
		},
		{ // in type switch
			in:    "package p; func f() {switch a();b().(type){}}",
			which: 2,
			want:  "package p; func f() {switch ;b().(type){}}",
			name:  "type0",
		},
		{ // but not the type cast
			in:    "package p; func f() {switch a();b().(type){}}",
			which: 3,
			want:  "package p; func f() {switch a();b().(type){}}",
			name:  "type1",
		},
		{ // if
			in:    "package p; func f() {if a();b() {}}",
			which: 2,
			want:  "package p; func f() {if ;b() {}}",
			name:  "if0",
		},
		{ // cannot remove the else
			in:    "package p\nfunc _() { if a() {}  else {b()}}",
			which: 3,
			want:  "package p\nfunc _() { if a() {}  else {b()}}",
			name:  "else0",
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			fset := token.NewFileSet()
			f, err := parser.ParseFile(fset, tt.name, tt.in, parser.ParseComments)
			if err != nil {
				t.Fatalf("%s: %v", tt.name, err)
			}
			insp := inspector.New([]*ast.File{f})
			root := insp.Root()
			var stmt inspector.Cursor
			cnt := 0
			for cn := range root.Preorder() { // Preorder(ast.Stmt(nil)) doesn't work
				if _, ok := cn.Node().(ast.Stmt); !ok {
					continue
				}
				if cnt == tt.which {
					stmt = cn
					break
				}
				cnt++
			}
			if cnt != tt.which {
				t.Fatalf("test %s does not contain desired statement %d", tt.name, tt.which)
			}
			tokFile := fset.File(f.Pos())
			edits := refactor.DeleteStmt(tokFile, stmt)
			if tt.want == tt.in {
				if len(edits) != 0 {
					t.Fatalf("%s: got %d edits, expected 0", tt.name, len(edits))
				}
				return
			}
			if len(edits) != 1 {
				t.Fatalf("%s: got %d edits, expected 1", tt.name, len(edits))
			}

			left := tokFile.Offset(edits[0].Pos)
			right := tokFile.Offset(edits[0].End)

			got := tt.in[:left] + tt.in[right:]
			if got != tt.want {
				t.Errorf("%s: got\n%q, want\n%q", tt.name, got, tt.want)
			}
		})

	}
}

func TestDeleteVar(t *testing.T) {
	// Each example deletes var v.
	for i, test := range []struct {
		src  string
		want string
	}{
		// package-level GenDecl > ValueSpec
		{
			"package p; var v int",
			"package p; ",
		},
		{
			"package p; var x, v int",
			"package p; var x int",
		},
		{
			"package p; var v, x int",
			"package p; var x int",
		},
		{
			"package p; var ( v int )",
			"package p;",
		},
		{
			"package p; var ( x, v int )",
			"package p; var ( x int )",
		},
		{
			"package p; var ( v, x int )",
			"package p; var ( x int )",
		},
		{
			"package p; var v, x = 1, 2",
			"package p; var x = 2",
		},
		{
			"package p; var x, v = 1, 2",
			"package p; var x = 1",
		},
		{
			"package p; var v, x = fx(), fx()",
			"package p; var _, x = fx(), fx()",
		},
		{
			"package p; var v, _ = fx(), fx()",
			"package p; var _, _ = fx(), fx()",
		},
		{
			"package p; var _, v = fx(), fx()",
			"package p; var _, _ = fx(), fx()",
		},
		{
			"package p; var v = fx()",
			"package p; var _ = fx()",
		},
		{
			"package p; var ( a int; v int; c int )",
			"package p; var ( a int; c int )",
		},
		{
			"package p; var ( a int; v int = 2; c int )",
			"package p; var ( a int; c int )",
		},
		// GenDecl doc comments are not deleted unless decl is deleted.
		{
			"package p\n// comment\nvar ( v int )",
			"package p",
		},
		{
			"package p\n// comment\nvar v int",
			"package p",
		},
		{
			"package p\n/* comment */\nvar v int",
			"package p",
		},
		{
			"package p\n// comment\nvar ( v, x int )",
			"package p\n// comment\nvar ( x int )",
		},
		{
			"package p\n// comment\nvar v, x int",
			"package p\n// comment\nvar x int",
		},
		{
			"package p\n/* comment */\nvar x, v int",
			"package p\n/* comment */\nvar x int",
		},
		// ValueSpec leading doc comments
		{
			"package p\nvar (\n// comment\nv int; x int )",
			"package p\nvar (\nx int )",
		},
		{
			"package p\nvar (\n// comment\nx int; v int )",
			"package p\nvar (\n// comment\nx int )",
		},
		// ValueSpec trailing line comments
		{
			"package p; var ( v int // comment\nx int )",
			"package p; var ( x int )",
		},
		{
			"package p; var ( x int // comment\nv int )",
			"package p; var ( x int // comment\n )",
		},
		{
			"package p; var ( v int /* comment */)",
			"package p;",
		},
		{
			"package p; var ( v int // comment\n)",
			"package p;",
		},
		{
			"package p; var ( v int ) // comment",
			"package p;",
		},
		{
			"package p; var ( x, v int /* comment */ )",
			"package p; var ( x int /* comment */ )",
		},
		{
			"package p; var ( v, x int /* comment */ )",
			"package p; var ( x int /* comment */ )",
		},
		{
			"package p; var ( x, v int // comment\n)",
			"package p; var ( x int // comment\n)",
		},
		{
			"package p; var ( v, x int // comment\n)",
			"package p; var ( x int // comment\n)",
		},
		{
			"package p; var ( v, x int ) // comment",
			"package p; var ( x int ) // comment",
		},
		{
			"package p; var ( x int; v int // comment\n)",
			"package p; var ( x int )",
		},
		{
			"package p; var ( v int // comment\n x int )",
			"package p; var ( x int )",
		},
		// local DeclStmt > GenDecl > ValueSpec
		// (The only interesting cases
		// here are the total deletions.)
		{
			"package p; func _() { var v int }",
			"package p; func _() {}",
		},
		{
			"package p; func _() { var ( v int ) }",
			"package p; func _() {}",
		},
		{
			"package p; func _() { var ( v int // comment\n) }",
			"package p; func _() {}",
		},
		{
			"package p; func _() { var ( v int ) // comment\n }",
			"package p; func _() { \n}",
		},
		{
			"package p; func _() { var v int // comment\n }",
			"package p; func _() { \n}",
		},
		// AssignStmt
		{
			"package p; func _() { v := 0 }",
			"package p; func _() {}",
		},
		{
			"package p; func _() { x, v := 0, 1 }",
			"package p; func _() { x := 0 }",
		},
		{
			"package p; func _() { v, x := 0, 1 }",
			"package p; func _() { x := 1 }",
		},
		{
			"package p; func _() { v, x := f() }",
			"package p; func _() { _, x := f() }",
		},
		{
			"package p; func _() { v, x := fx(), fx() }",
			"package p; func _() { _, x := fx(), fx() }",
		},
		{
			"package p; func _() { v, _ := fx(), fx() }",
			"package p; func _() { _, _ = fx(), fx() }",
		},
		{
			"package p; func _() { _, v := fx(), fx() }",
			"package p; func _() { _, _ = fx(), fx() }",
		},
		{
			"package p; func _() { v := fx() }",
			"package p; func _() { _ = fx() }",
		},
		{
			"package p; func _() { v := 1 // comment\n }",
			"package p; func _() { \n}",
		},
		{
			"package p; func _() { v, x := 0, 1 // comment\n }",
			"package p; func _() { x := 1 // comment\n }",
		},
		{
			"package p; func _() { if v := 1; cond {} }",
			"package p; func _() { if ; cond {} }",
		},
		{
			"package p; func _() { if v, x := 1, 2; cond {} }",
			"package p; func _() { if x := 2; cond {} }",
		},
		{
			"package p; func _() { switch v := 0; cond {} }",
			"package p; func _() { switch cond {} }",
		},
		{
			"package p; func _() { switch v := fx(); cond {} }",
			"package p; func _() { switch _ = fx(); cond {} }",
		},
		{
			"package p; func _() { for v := 0; ; {} }",
			"package p; func _() { for {} }",
		},
		// unhandled cases
		{
			"package p; func _(v int) {}", // parameter
			"package p; func _(v int) {}",
		},
		{
			"package p; func _() (v int) {}", // result
			"package p; func _() (v int) {}",
		},
		{
			"package p; type T int; func _(v T) {}", // receiver
			"package p; type T int; func _(v T) {}",
		},
		// There is no defining Ident in this case.
		// {
		// 	"package p; func _() { switch v := any(nil).(type) {} }",
		// 	"package p; func _() { switch v := any(nil).(type) {} }",
		// },
	} {
		t.Run(fmt.Sprint(i), func(t *testing.T) {
			t.Logf("src: %s", test.src)
			fset := token.NewFileSet()
			f, _ := parser.ParseFile(fset, "p", test.src, parser.ParseComments) // allow errors
			conf := types.Config{
				Error: func(err error) {}, // allow errors
			}
			info := &types.Info{
				Types: make(map[ast.Expr]types.TypeAndValue),
				Defs:  make(map[*ast.Ident]types.Object),
			}
			files := []*ast.File{f}
			conf.Check("p", fset, files, info) // ignore error

			curId := func() inspector.Cursor {
				for curId := range inspector.New(files).Root().Preorder((*ast.Ident)(nil)) {
					id := curId.Node().(*ast.Ident)
					if id.Name == "v" && info.Defs[id] != nil {
						return curId
					}
				}
				t.Fatalf("can't find Defs[v]")
				panic("unreachable")
			}()
			tokFile := fset.File(f.Pos())
			edits := refactor.DeleteVar(tokFile, info, curId)

			// TODO(adonovan): extract this helper for
			// applying TextEdits and comparing against
			// expectations. (This code was mostly copied
			// from analysistest.)
			var dedits []diff.Edit
			for _, edit := range edits {
				file := fset.File(edit.Pos)
				dedits = append(dedits, diff.Edit{
					Start: file.Offset(edit.Pos),
					End:   file.Offset(edit.End),
					New:   string(edit.NewText),
				})
			}
			fixed, err := diff.ApplyBytes([]byte(test.src), dedits)
			if err != nil {
				t.Fatalf("diff.Apply: %v", err)
			}
			t.Logf("fixed: %s", fixed)
			fixed, err = format.Source(fixed)
			if err != nil {
				t.Fatalf("format: %v", err)
			}
			want, err := format.Source([]byte(test.want))
			if err != nil {
				t.Fatalf("formatting want: %v", err)
			}
			t.Logf("want: %s", want)
			unified := func(xlabel, ylabel string, x, y []byte) string {
				x = append(slices.Clip(bytes.TrimSpace(x)), '\n')
				y = append(slices.Clip(bytes.TrimSpace(y)), '\n')
				return diff.Unified(xlabel, ylabel, string(x), string(y))
			}
			if diff := unified("fixed", "want", fixed, want); diff != "" {
				t.Errorf("-- diff original fixed --\n%s\n"+
					"-- diff fixed want --\n%s",
					unified("original", "fixed", []byte(test.src), fixed),
					diff)
			}
		})
	}
}


================================================
FILE: internal/refactor/edit.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.p

package refactor

// This is the only file in this package that should import analysis.
//
// TODO(adonovan): consider unaliasing the type to break the
// dependency. (The ergonomics of slice append are unfortunate.)

import "golang.org/x/tools/go/analysis"

// An Edit describes a deletion and/or an insertion.
type Edit = analysis.TextEdit


================================================
FILE: internal/refactor/imports.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package refactor

// This file defines operations for computing edits to imports.

import (
	"go/ast"
	"go/token"
	"go/types"
	pathpkg "path"
	"strconv"

	"golang.org/x/tools/internal/packagepath"
)

// AddImport returns the prefix (either "pkg." or "") that should be
// used to qualify references to the desired symbol (member) imported
// from the specified package, plus any necessary edits to the file's
// import declaration to add a new import.
//
// If the import already exists, and is accessible at pos, AddImport
// returns the existing name and no edits. (If the existing import is
// a dot import, the prefix is "".)
//
// Otherwise, it adds a new import, using a local name derived from
// the preferred name. To request a blank import, use a preferredName
// of "_", and discard the prefix result; member is ignored in this
// case.
//
// AddImport accepts the caller's implicit claim that the imported
// package declares member.
//
// AddImport does not mutate its arguments.
func AddImport(info *types.Info, file *ast.File, preferredName, pkgpath, member string, pos token.Pos) (prefix string, edits []Edit) {
	// Find innermost enclosing lexical block.
	scope := info.Scopes[file].Innermost(pos)
	if scope == nil {
		panic("no enclosing lexical block")
	}

	// Is there an existing import of this package?
	// If so, are we in its scope? (not shadowed)
	for _, spec := range file.Imports {
		pkgname := info.PkgNameOf(spec)
		if pkgname != nil && pkgname.Imported().Path() == pkgpath {
			name := pkgname.Name()
			if preferredName == "_" {
				// Request for blank import; any existing import will do.
				return "", nil
			}
			if name == "." {
				// The scope of ident must be the file scope.
				if s, _ := scope.LookupParent(member, pos); s == info.Scopes[file] {
					return "", nil
				}
			} else if _, obj := scope.LookupParent(name, pos); obj == pkgname {
				return name + ".", nil
			}
		}
	}

	// We must add a new import.

	// Ensure we have a fresh name.
	newName := preferredName
	if preferredName != "_" {
		newName = FreshName(scope, pos, preferredName)
		prefix = newName + "."
	}

	// Use a renaming import whenever the preferred name is not
	// available, or the chosen name does not match the last
	// segment of its path.
	if newName == preferredName && newName == pathpkg.Base(pkgpath) {
		newName = ""
	}

	return prefix, AddImportEdits(file, newName, pkgpath)
}

// AddImportEdits returns the edits to add an import of the specified
// package, without any analysis of whether this is necessary or safe.
// If name is nonempty, it is used as an explicit [ImportSpec.Name].
//
// A sequence of calls to AddImportEdits that each add the file's
// first import (or in a file that does not have a grouped import) may
// result in multiple import declarations, rather than a single one
// with multiple ImportSpecs. However, a subsequent run of
// x/tools/cmd/goimports ([imports.Process]) will combine them.
//
// AddImportEdits does not mutate the AST.
func AddImportEdits(file *ast.File, name, pkgpath string) []Edit {
	newText := strconv.Quote(pkgpath)
	if name != "" {
		newText = name + " " + newText
	}

	// Create a new import declaration either before the first existing
	// declaration (which must exist), including its comments; or
	// inside the declaration, if it is an import group.
	decl0 := file.Decls[0]
	before := decl0.Pos()
	switch decl0 := decl0.(type) {
	case *ast.GenDecl:
		if decl0.Doc != nil {
			before = decl0.Doc.Pos()
		}
	case *ast.FuncDecl:
		if decl0.Doc != nil {
			before = decl0.Doc.Pos()
		}
	}
	var pos token.Pos
	if gd, ok := decl0.(*ast.GenDecl); ok && gd.Tok == token.IMPORT && gd.Rparen.IsValid() {
		// Have existing grouped import ( ... ) decl.
		if packagepath.IsStdPackage(pkgpath) && len(gd.Specs) > 0 {
			// Add spec for a std package before
			// first existing spec, followed by
			// a blank line if the next one is non-std.
			first := gd.Specs[0].(*ast.ImportSpec)
			pos = first.Pos()
			if !packagepath.IsStdPackage(first.Path.Value) {
				newText += "\n"
			}
			newText += "\n\t"
		} else {
			// Add spec at end of group.
			pos = gd.Rparen
			newText = "\t" + newText + "\n"
		}
	} else {
		// No import decl, or non-grouped import.
		// Add a new import decl before first decl.
		// (gofmt will merge multiple import decls.)
		//
		// TODO(adonovan): do better here; plunder the
		// mergeImports logic from [imports.Process].
		pos = before
		newText = "import " + newText + "\n\n"
	}
	return []Edit{{
		Pos:     pos,
		End:     pos,
		NewText: []byte(newText),
	}}
}


================================================
FILE: internal/refactor/imports_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package refactor_test

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"runtime"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/testenv"
)

func TestAddImport(t *testing.T) {
	testenv.NeedsDefaultImporter(t)

	descr := func(s string) string {
		if _, _, line, ok := runtime.Caller(1); ok {
			return fmt.Sprintf("L%d %s", line, s)
		}
		panic("runtime.Caller failed")
	}

	// Each test case contains a «name pkgpath member»
	// triple to be replaced with a valid qualified identifier
	// to pkgpath.member, ideally of the specified name.
	for _, test := range []struct {
		descr, src, want string
	}{
		{
			descr: descr("simple add import"),
			src: `package a
func _() {
	«fmt fmt Print»
}`,
			want: `package a
import "fmt"

func _() {
	fmt.Print
}`,
		},
		{
			descr: descr("existing import"),
			src: `package a

import "fmt"

func _(fmt.Stringer) {
	«fmt fmt Print»
}`,
			want: `package a

import "fmt"

func _(fmt.Stringer) {
	fmt.Print
}`,
		},
		{
			descr: descr("existing blank import"),
			src: `package a

import _ "fmt"

func _() {
	«fmt fmt Print»
}`,
			want: `package a

import "fmt"

import _ "fmt"

func _() {
	fmt.Print
}`,
		},
		{
			descr: descr("existing renaming import"),
			src: `package a

import fmtpkg "fmt"

var fmt int

func _(fmtpkg.Stringer) {
	«fmt fmt Print»
}`,
			want: `package a

import fmtpkg "fmt"

var fmt int

func _(fmtpkg.Stringer) {
	fmtpkg.Print
}`,
		},
		{
			descr: descr("existing import is shadowed"),
			src: `package a

import "fmt"

var _ fmt.Stringer

func _(fmt int) {
	«fmt fmt Print»
}`,
			want: `package a

import fmt0 "fmt"

import "fmt"

var _ fmt.Stringer

func _(fmt int) {
	fmt0.Print
}`,
		},
		{
			descr: descr("preferred name is shadowed"),
			src: `package a

import "fmt"

func _(fmt fmt.Stringer) {
	«fmt fmt Print»
}`,
			want: `package a

import fmt0 "fmt"

import "fmt"

func _(fmt fmt.Stringer) {
	fmt0.Print
}`,
		},
		{
			descr: descr("import inserted before doc comments"),
			src: `package a

// hello
import "os"

// world
func _() {
	«fmt fmt Print»
}`,
			want: `package a

import "fmt"

// hello
import "os"

// world
func _() {
	fmt.Print
}`,
		},
		{
			descr: descr("arbitrary preferred name => renaming import"),
			src: `package a

func _() {
	«foo encoding/json Marshal»
}`,
			want: `package a

import foo "encoding/json"

func _() {
	foo.Marshal
}`,
		},
		{
			descr: descr("dot import unshadowed"),
			src: `package a

import . "fmt"

func _() {
	«. fmt Print»
}`,
			want: `package a

import . "fmt"

func _() {
	Print
}`,
		},
		{
			descr: descr("dot import shadowed"),
			src: `package a

import . "fmt"

func _(Print fmt.Stringer) {
	«fmt fmt Print»
}`,
			want: `package a

import "fmt"

import . "fmt"

func _(Print fmt.Stringer) {
	fmt.Print
}`,
		},
		{
			descr: descr("add import to group"),
			src: `package a

import (
	"io"
)

func _(io.Reader) {
	«fmt fmt Print»
}`,
			want: `package a

import (
	"fmt"
	"io"
)

func _(io.Reader) {
	fmt.Print
}`,
		},
		{
			descr: descr("add import to group which imports std and a 3rd module"),
			src: `package a

import (
	"io"

	"vendor/golang.org/x/net/dns/dnsmessage"
)

func _(io.Reader) {
	«fmt fmt Print»
}`,
			want: `package a

import (
	"fmt"
	"io"

	"vendor/golang.org/x/net/dns/dnsmessage"
)

func _(io.Reader) {
	fmt.Print
}`,
		},
		{
			descr: descr("add import to group which imports std and a 3rd module without parens"),
			src: `package a

import "io"

import "vendor/golang.org/x/net/dns/dnsmessage"

func _(io.Reader) {
	«fmt fmt Print»
}`,
			want: `package a

import "fmt"

import "io"

import "vendor/golang.org/x/net/dns/dnsmessage"

func _(io.Reader) {
	fmt.Print
}`,
		},
		{
			descr: descr("add import to group without std import"),
			src: `package a

import (
	"golang.org/x/tools/go/packages"
	gossa "golang.org/x/tools/go/ssa"
)

func _(io.Reader) {
	«fmt fmt Print»
}`,
			want: `package a

import (
	"fmt"

	"golang.org/x/tools/go/packages"
	gossa "golang.org/x/tools/go/ssa"
)

func _(io.Reader) {
	fmt.Print
}`,
		},
	} {
		t.Run(test.descr, func(t *testing.T) {
			// splice marker (name pkgpath member)
			before, mid, ok1 := strings.Cut(test.src, "«")
			mid, after, ok2 := strings.Cut(mid, "»")
			if !ok1 || !ok2 {
				t.Fatal("no «name path member» marker")
			}
			src := before + "/*!*/" + after
			fields := strings.Fields(mid)
			if len(fields) != 3 {
				t.Fatalf("splice marker needs 3 fields (got %q)", mid)
			}
			name, path, member := fields[0], fields[1], fields[2]

			// parse
			fset := token.NewFileSet()
			f, err := parser.ParseFile(fset, "a.go", src, parser.ParseComments)
			if err != nil {
				t.Log(err)
			}
			pos := fset.File(f.FileStart).Pos(len(before))

			// type-check
			info := &types.Info{
				Types:     make(map[ast.Expr]types.TypeAndValue),
				Scopes:    make(map[ast.Node]*types.Scope),
				Defs:      make(map[*ast.Ident]types.Object),
				Implicits: make(map[ast.Node]types.Object),
			}
			conf := &types.Config{
				// We don't want to fail if there is an error during type checking:
				// the error may be because we're missing an import, and adding imports
				// is the whole point of AddImport.
				Error:    func(err error) { t.Log(err) },
				Importer: importer.Default(),
			}
			conf.Check(f.Name.Name, fset, []*ast.File{f}, info)

			prefix, edits := refactor.AddImport(info, f, name, path, member, pos)

			var edit refactor.Edit
			switch len(edits) {
			case 0:
			case 1:
				edit = edits[0]
			default:
				t.Fatalf("expected at most one edit, got %d", len(edits))
			}

			// apply patch
			start := fset.Position(edit.Pos)
			end := fset.Position(edit.End)
			output := src[:start.Offset] + string(edit.NewText) + src[end.Offset:]
			output = strings.ReplaceAll(output, "/*!*/", prefix+member)
			if output != test.want {
				t.Errorf("\n--got--\n%s\n--want--\n%s\n--diff--\n%s",
					output, test.want, cmp.Diff(test.want, output))
			}
		})
	}
}


================================================
FILE: internal/refactor/inline/callee.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

// This file defines the analysis of the callee function.

import (
	"bytes"
	"encoding/gob"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"slices"
	"strings"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
)

// A Callee holds information about an inlinable function. Gob-serializable.
type Callee struct {
	impl gobCallee
}

func (callee *Callee) String() string { return callee.impl.Name }

type gobCallee struct {
	Content []byte // file content, compacted to a single func decl

	// results of type analysis (does not reach go/types data structures)
	PkgPath          string                 // package path of declaring package
	Name             string                 // user-friendly name for error messages
	GoVersion        string                 // version of Go effective in callee file
	Unexported       []string               // names of free objects that are unexported
	FreeRefs         []freeRef              // locations of references to free objects
	FreeObjs         []object               // descriptions of free objects
	ValidForCallStmt bool                   // function body is "return expr" where expr is f() or <-ch
	NumResults       int                    // number of results (according to type, not ast.FieldList)
	Params           []*paramInfo           // information about parameters (incl. receiver)
	TypeParams       []*paramInfo           // information about type parameters
	Results          []*paramInfo           // information about result variables
	Effects          []int                  // order in which parameters are evaluated (see calleefx)
	HasDefer         bool                   // uses defer
	HasBareReturn    bool                   // uses bare return in non-void function
	Returns          [][]returnOperandFlags // metadata about result expressions for each return
	Labels           []string               // names of all control labels
	Falcon           falconResult           // falcon constraint system
}

// returnOperandFlags records metadata about a single result expression in a return
// statement.
type returnOperandFlags int

const (
	nonTrivialResult returnOperandFlags = 1 << iota // return operand has non-trivial conversion to result type
	untypedNilResult                                // return operand is nil literal
)

// A freeRef records a reference to a free object. Gob-serializable.
// (This means free relative to the FuncDecl as a whole, i.e. excluding parameters.)
type freeRef struct {
	Offset int // byte offset of the reference relative to the FuncDecl
	Object int // index into Callee.freeObjs
}

// An object abstracts a free types.Object referenced by the callee. Gob-serializable.
type object struct {
	Name    string // Object.Name()
	Kind    string // one of {var,func,const,type,pkgname,nil,builtin}
	PkgPath string // path of object's package (or imported package if kind="pkgname")
	PkgName string // name of object's package (or imported package if kind="pkgname")
	// TODO(rfindley): should we also track LocalPkgName here? Do we want to
	// preserve the local package name?
	ValidPos bool      // Object.Pos().IsValid()
	Shadow   shadowMap // shadowing info for the object's refs
}

// AnalyzeCallee analyzes a function that is a candidate for inlining
// and returns a Callee that describes it. The Callee object, which is
// serializable, can be passed to one or more subsequent calls to
// Inline, each with a different Caller.
//
// This design allows separate analysis of callers and callees in the
// golang.org/x/tools/go/analysis framework: the inlining information
// about a callee can be recorded as a "fact".
//
// The content should be the actual input to the compiler, not the
// apparent source file according to any //line directives that
// may be present within it.
func AnalyzeCallee(logf func(string, ...any), fset *token.FileSet, pkg *types.Package, info *types.Info, decl *ast.FuncDecl, content []byte) (*Callee, error) {
	checkInfoFields(info)

	// The client is expected to have determined that the callee
	// is a function with a declaration (not a built-in or var).
	fn := info.Defs[decl.Name].(*types.Func)
	sig := fn.Type().(*types.Signature)

	logf("analyzeCallee %v @ %v", fn, fset.PositionFor(decl.Pos(), false))

	// Create user-friendly name ("pkg.Func" or "(pkg.T).Method")
	var name string
	if sig.Recv() == nil {
		name = fmt.Sprintf("%s.%s", fn.Pkg().Name(), fn.Name())
	} else {
		name = fmt.Sprintf("(%s).%s", types.TypeString(sig.Recv().Type(), (*types.Package).Name), fn.Name())
	}

	if decl.Body == nil {
		return nil, fmt.Errorf("cannot inline function %s as it has no body", name)
	}

	// Record the file's Go goVersion so that we don't
	// inline newer code into file using an older dialect.
	//
	// Using the file version is overly conservative.
	// A more precise solution would be for the type checker to
	// record which language features the callee actually needs;
	// see https://go.dev/issue/75726.
	//
	// We don't have the ast.File handy, so instead of a
	// lookup we must scan the entire FileVersions map.
	var goVersion string
	for file, v := range info.FileVersions {
		if file.Pos() < decl.Pos() && decl.Pos() < file.End() {
			goVersion = v
			break
		}
	}

	// Record the location of all free references in the FuncDecl.
	// (Parameters are not free by this definition.)
	var (
		fieldObjs    = fieldObjs(sig)
		freeObjIndex = make(map[types.Object]int)
		freeObjs     []object
		freeRefs     []freeRef // free refs that may need renaming
		unexported   []string  // free refs to unexported objects, for later error checks
	)
	var f func(n ast.Node, stack []ast.Node) bool
	var stack []ast.Node
	stack = append(stack, decl.Type) // for scope of function itself
	visit := func(n ast.Node, stack []ast.Node) { ast.PreorderStack(n, stack, f) }
	f = func(n ast.Node, stack []ast.Node) bool {
		switch n := n.(type) {
		case *ast.SelectorExpr:
			// Check selections of free fields/methods.
			if sel, ok := info.Selections[n]; ok &&
				!within(sel.Obj().Pos(), decl) &&
				!n.Sel.IsExported() {
				sym := fmt.Sprintf("(%s).%s", info.TypeOf(n.X), n.Sel.Name)
				unexported = append(unexported, sym)
			}

			// Don't recur into SelectorExpr.Sel.
			visit(n.X, stack)
			return false

		case *ast.CompositeLit:
			// Check for struct literals that refer to unexported fields,
			// whether keyed or unkeyed. (Logic assumes well-typedness.)
			litType := typeparams.Deref(info.TypeOf(n))
			if s, ok := typeparams.CoreType(litType).(*types.Struct); ok {
				if n.Type != nil {
					visit(n.Type, stack)
				}
				for i, elt := range n.Elts {
					var field *types.Var
					var value ast.Expr
					if kv, ok := elt.(*ast.KeyValueExpr); ok {
						field = info.Uses[kv.Key.(*ast.Ident)].(*types.Var)
						value = kv.Value
					} else {
						field = s.Field(i)
						value = elt
					}
					if !within(field.Pos(), decl) && !field.Exported() {
						sym := fmt.Sprintf("(%s).%s", litType, field.Name())
						unexported = append(unexported, sym)
					}

					// Don't recur into KeyValueExpr.Key.
					visit(value, stack)
				}
				return false
			}

		case *ast.Ident:
			if obj, ok := info.Uses[n]; ok {
				// Methods and fields are handled by SelectorExpr and CompositeLit.
				if isField(obj) || isMethod(obj) {
					panic(obj)
				}
				// Inv: id is a lexical reference.

				// A reference to an unexported package-level declaration
				// cannot be inlined into another package.
				if !n.IsExported() &&
					obj.Pkg() != nil && obj.Parent() == obj.Pkg().Scope() {
					unexported = append(unexported, n.Name)
				}

				// Record free reference (incl. self-reference).
				if obj == fn || !within(obj.Pos(), decl) {
					objidx, ok := freeObjIndex[obj]
					if !ok {
						objidx = len(freeObjIndex)
						var pkgPath, pkgName string
						if pn, ok := obj.(*types.PkgName); ok {
							pkgPath = pn.Imported().Path()
							pkgName = pn.Imported().Name()
						} else if obj.Pkg() != nil {
							pkgPath = obj.Pkg().Path()
							pkgName = obj.Pkg().Name()
						}
						freeObjs = append(freeObjs, object{
							Name:     obj.Name(),
							Kind:     objectKind(obj),
							PkgName:  pkgName,
							PkgPath:  pkgPath,
							ValidPos: obj.Pos().IsValid(),
						})
						freeObjIndex[obj] = objidx
					}

					freeObjs[objidx].Shadow = freeObjs[objidx].Shadow.add(info, fieldObjs, obj.Name(), stack)

					freeRefs = append(freeRefs, freeRef{
						Offset: int(n.Pos() - decl.Pos()),
						Object: objidx,
					})
				}
			}
		}
		return true
	}
	visit(decl, stack)

	// Analyze callee body for "return expr" form,
	// where expr is f() or <-ch. These forms are
	// safe to inline as a standalone statement.
	validForCallStmt := false
	if len(decl.Body.List) != 1 {
		// not just a return statement
	} else if ret, ok := decl.Body.List[0].(*ast.ReturnStmt); ok && len(ret.Results) == 1 {
		validForCallStmt = func() bool {
			switch expr := ast.Unparen(ret.Results[0]).(type) {
			case *ast.CallExpr: // f(x)
				callee := typeutil.Callee(info, expr)
				if callee == nil {
					return false // conversion T(x)
				}

				// The only non-void built-in functions that may be
				// called as a statement are copy and recover
				// (though arguably a call to recover should never
				// be inlined as that changes its behavior).
				if builtin, ok := callee.(*types.Builtin); ok {
					return builtin.Name() == "copy" ||
						builtin.Name() == "recover"
				}

				return true // ordinary call f()

			case *ast.UnaryExpr: // <-x
				return expr.Op == token.ARROW // channel receive <-ch
			}

			// No other expressions are valid statements.
			return false
		}()
	}

	// Record information about control flow in the callee
	// (but not any nested functions).
	var (
		hasDefer      = false
		hasBareReturn = false
		returnInfo    [][]returnOperandFlags
		labels        []string
	)
	ast.Inspect(decl.Body, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.FuncLit:
			return false // prune traversal
		case *ast.DeferStmt:
			hasDefer = true
		case *ast.LabeledStmt:
			labels = append(labels, n.Label.Name)
		case *ast.ReturnStmt:

			// Are implicit assignment conversions
			// to result variables all trivial?
			var resultInfo []returnOperandFlags
			if len(n.Results) > 0 {
				argInfo := func(i int) (ast.Expr, types.Type) {
					expr := n.Results[i]
					return expr, info.TypeOf(expr)
				}
				if len(n.Results) == 1 && sig.Results().Len() > 1 {
					// Spread return: return f() where f.Results > 1.
					tuple := info.TypeOf(n.Results[0]).(*types.Tuple)
					argInfo = func(i int) (ast.Expr, types.Type) {
						return nil, tuple.At(i).Type()
					}
				}
				for i := range sig.Results().Len() {
					expr, typ := argInfo(i)
					var flags returnOperandFlags
					if typ == types.Typ[types.UntypedNil] { // untyped nil is preserved by go/types
						flags |= untypedNilResult
					}
					if !trivialConversion(info.Types[expr].Value, typ, sig.Results().At(i).Type()) {
						flags |= nonTrivialResult
					}
					resultInfo = append(resultInfo, flags)
				}
			} else if sig.Results().Len() > 0 {
				hasBareReturn = true
			}
			returnInfo = append(returnInfo, resultInfo)
		}
		return true
	})

	// Reject attempts to inline cgo-generated functions.
	for _, obj := range freeObjs {
		// There are others (iconst fconst sconst fpvar macro)
		// but this is probably sufficient.
		if strings.HasPrefix(obj.Name, "_Cfunc_") ||
			strings.HasPrefix(obj.Name, "_Ctype_") ||
			strings.HasPrefix(obj.Name, "_Cvar_") {
			return nil, fmt.Errorf("cannot inline cgo-generated functions")
		}
	}

	// Compact content to just the FuncDecl.
	//
	// As a space optimization, we don't retain the complete
	// callee file content; all we need is "package _; func f() { ... }".
	// This reduces the size of analysis facts.
	//
	// Offsets in the callee information are "relocatable"
	// since they are all relative to the FuncDecl.

	content = append([]byte("package _\n"),
		content[offsetOf(fset, decl.Pos()):offsetOf(fset, decl.End())]...)
	// Sanity check: re-parse the compacted content.
	if _, _, err := parseCompact(content); err != nil {
		return nil, err
	}

	params, results, effects, falcon := analyzeParams(logf, fset, info, decl)
	tparams := analyzeTypeParams(logf, fset, info, decl)
	return &Callee{gobCallee{
		Content:          content,
		PkgPath:          pkg.Path(),
		Name:             name,
		GoVersion:        goVersion,
		Unexported:       unexported,
		FreeObjs:         freeObjs,
		FreeRefs:         freeRefs,
		ValidForCallStmt: validForCallStmt,
		NumResults:       sig.Results().Len(),
		Params:           params,
		TypeParams:       tparams,
		Results:          results,
		Effects:          effects,
		HasDefer:         hasDefer,
		HasBareReturn:    hasBareReturn,
		Returns:          returnInfo,
		Labels:           labels,
		Falcon:           falcon,
	}}, nil
}

// parseCompact parses a Go source file of the form "package _\n func f() { ... }"
// and returns the sole function declaration.
func parseCompact(content []byte) (*token.FileSet, *ast.FuncDecl, error) {
	fset := token.NewFileSet()
	const mode = parser.ParseComments | parser.SkipObjectResolution | parser.AllErrors
	f, err := parser.ParseFile(fset, "callee.go", content, mode)
	if err != nil {
		return nil, nil, fmt.Errorf("internal error: cannot compact file: %v", err)
	}
	return fset, f.Decls[0].(*ast.FuncDecl), nil
}

// A paramInfo records information about a callee receiver, parameter, or result variable.
type paramInfo struct {
	Name        string    // parameter name (may be blank, or even "")
	Index       int       // index within signature
	IsResult    bool      // false for receiver or parameter, true for result variable
	IsInterface bool      // parameter has a (non-type parameter) interface type
	Assigned    bool      // parameter appears on left side of an assignment statement
	Escapes     bool      // parameter has its address taken
	Refs        []refInfo // information about references to parameter within body
	Shadow      shadowMap // shadowing info for the above refs; see [shadowMap]
	FalconType  string    // name of this parameter's type (if basic) in the falcon system
}

type refInfo struct {
	Offset           int  // FuncDecl-relative byte offset of parameter ref within body
	Assignable       bool // ref appears in context of assignment to known type
	IfaceAssignment  bool // ref is being assigned to an interface
	AffectsInference bool // ref type may affect type inference
	// IsSelectionOperand indicates whether the parameter reference is the
	// operand of a selection (param.f). If so, and param's argument is itself
	// a receiver parameter (a common case), we don't need to desugar (&v or *ptr)
	// the selection: if param.Method is a valid selection, then so is param.fieldOrMethod.
	IsSelectionOperand bool
}

// analyzeParams computes information about parameters of the function declared by decl,
// including a simple "address taken" escape analysis.
//
// It returns two new arrays, one of the receiver and parameters, and
// the other of the result variables of the function.
//
// The input must be well-typed.
func analyzeParams(logf func(string, ...any), fset *token.FileSet, info *types.Info, decl *ast.FuncDecl) (params, results []*paramInfo, effects []int, _ falconResult) {
	sig := signature(fset, info, decl)

	paramInfos := make(map[*types.Var]*paramInfo)
	{
		newParamInfo := func(param *types.Var, isResult bool) *paramInfo {
			info := &paramInfo{
				Name:        param.Name(),
				IsResult:    isResult,
				Index:       len(paramInfos),
				IsInterface: isNonTypeParamInterface(param.Type()),
			}
			paramInfos[param] = info
			return info
		}
		if sig.Recv() != nil {
			params = append(params, newParamInfo(sig.Recv(), false))
		}
		for v := range sig.Params().Variables() {
			params = append(params, newParamInfo(v, false))
		}
		for v := range sig.Results().Variables() {
			results = append(results, newParamInfo(v, true))
		}
	}

	// Search function body for operations &x, x.f(), and x = y
	// where x is a parameter, and record it.
	escape(info, decl, func(v *types.Var, escapes bool) {
		if info := paramInfos[v]; info != nil {
			if escapes {
				info.Escapes = true
			} else {
				info.Assigned = true
			}
		}
	})

	// Record locations of all references to parameters.
	// And record the set of intervening definitions for each parameter.
	//
	// TODO(adonovan): combine this traversal with the one that computes
	// FreeRefs. The tricky part is that calleefx needs this one first.
	fieldObjs := fieldObjs(sig)
	var stack []ast.Node
	stack = append(stack, decl.Type) // for scope of function itself
	ast.PreorderStack(decl.Body, stack, func(n ast.Node, stack []ast.Node) bool {
		if id, ok := n.(*ast.Ident); ok {
			if v, ok := info.Uses[id].(*types.Var); ok {
				if pinfo, ok := paramInfos[v]; ok {
					// Record ref information, and any intervening (shadowing) names.
					//
					// If the parameter v has an interface type, and the reference id
					// appears in a context where assignability rules apply, there may be
					// an implicit interface-to-interface widening. In that case it is
					// not necessary to insert an explicit conversion from the argument
					// to the parameter's type.
					//
					// Contrapositively, if param is not an interface type, then the
					// assignment may lose type information, for example in the case that
					// the substituted expression is an untyped constant or unnamed type.
					stack = append(stack, n) // (the two calls below want n)
					assignable, ifaceAssign, affectsInference := analyzeAssignment(info, stack)
					ref := refInfo{
						Offset:             int(n.Pos() - decl.Pos()),
						Assignable:         assignable,
						IfaceAssignment:    ifaceAssign,
						AffectsInference:   affectsInference,
						IsSelectionOperand: isSelectionOperand(stack),
					}
					pinfo.Refs = append(pinfo.Refs, ref)
					pinfo.Shadow = pinfo.Shadow.add(info, fieldObjs, pinfo.Name, stack)
				}
			}
		}
		return true
	})

	// Compute subset and order of parameters that are strictly evaluated.
	// (Depends on Refs computed above.)
	effects = calleefx(info, decl.Body, paramInfos)
	logf("effects list = %v", effects)

	falcon := falcon(logf, fset, paramInfos, info, decl)

	return params, results, effects, falcon
}

// analyzeTypeParams computes information about the type parameters of the function declared by decl.
func analyzeTypeParams(_ logger, fset *token.FileSet, info *types.Info, decl *ast.FuncDecl) []*paramInfo {
	sig := signature(fset, info, decl)
	paramInfos := make(map[*types.TypeName]*paramInfo)
	var params []*paramInfo
	collect := func(tpl *types.TypeParamList) {
		for tparam := range tpl.TypeParams() {
			typeName := tparam.Obj()
			info := &paramInfo{Name: typeName.Name()}
			params = append(params, info)
			paramInfos[typeName] = info
		}
	}
	collect(sig.RecvTypeParams())
	collect(sig.TypeParams())

	// Find references.
	// We don't care about most of the properties that matter for parameter references:
	// a type is immutable, cannot have its address taken, and does not undergo conversions.
	// TODO(jba): can we nevertheless combine this with the traversal in analyzeParams?
	var stack []ast.Node
	stack = append(stack, decl.Type) // for scope of function itself
	ast.PreorderStack(decl.Body, stack, func(n ast.Node, stack []ast.Node) bool {
		if id, ok := n.(*ast.Ident); ok {
			if v, ok := info.Uses[id].(*types.TypeName); ok {
				if pinfo, ok := paramInfos[v]; ok {
					ref := refInfo{Offset: int(n.Pos() - decl.Pos())}
					pinfo.Refs = append(pinfo.Refs, ref)
					pinfo.Shadow = pinfo.Shadow.add(info, nil, pinfo.Name, stack)
				}
			}
		}
		return true
	})
	return params
}

func signature(fset *token.FileSet, info *types.Info, decl *ast.FuncDecl) *types.Signature {
	fnobj, ok := info.Defs[decl.Name]
	if !ok {
		panic(fmt.Sprintf("%s: no func object for %q",
			fset.PositionFor(decl.Name.Pos(), false), decl.Name)) // ill-typed?
	}
	return fnobj.Type().(*types.Signature)
}

// -- callee helpers --

// analyzeAssignment looks at the given stack, and analyzes certain
// attributes of the innermost expression.
//
// In all cases we 'fail closed' when we cannot detect (or for simplicity
// choose not to detect) the condition in question, meaning we err on the side
// of the more restrictive rule. This is noted for each result below.
//
//   - assignable reports whether the expression is used in a position where
//     assignability rules apply, such as in an actual assignment, as call
//     argument, or in a send to a channel. Defaults to 'false'. If assignable
//     is false, the other two results are irrelevant.
//   - ifaceAssign reports whether that assignment is to an interface type.
//     This is important as we want to preserve the concrete type in that
//     assignment. Defaults to 'true'. Notably, if the assigned type is a type
//     parameter, we assume that it could have interface type.
//   - affectsInference is (somewhat vaguely) defined as whether or not the
//     type of the operand may affect the type of the surrounding syntax,
//     through type inference. It is infeasible to completely reverse engineer
//     type inference, so we over approximate: if the expression is an argument
//     to a call to a generic function (but not method!) that uses type
//     parameters, assume that unification of that argument may affect the
//     inferred types.
func analyzeAssignment(info *types.Info, stack []ast.Node) (assignable, ifaceAssign, affectsInference bool) {
	remaining, parent, expr := exprContext(stack)
	if parent == nil {
		return false, false, false
	}

	// TODO(golang/go#70638): simplify when types.Info records implicit conversions.

	// Types do not need to match for assignment to a variable.
	if assign, ok := parent.(*ast.AssignStmt); ok {
		for i, v := range assign.Rhs {
			if v == expr {
				if i >= len(assign.Lhs) {
					return false, false, false // ill typed
				}
				// Check to see if the assignment is to an interface type.
				if i < len(assign.Lhs) {
					// TODO: We could handle spread calls here, but in current usage expr
					// is an ident.
					if id, _ := assign.Lhs[i].(*ast.Ident); id != nil && info.Defs[id] != nil {
						// Types must match for a defining identifier in a short variable
						// declaration.
						return false, false, false
					}
					// In all other cases, types should be known.
					typ := info.TypeOf(assign.Lhs[i])
					return true, typ == nil || types.IsInterface(typ), false
				}
				// Default:
				return assign.Tok == token.ASSIGN, true, false
			}
		}
	}

	// Types do not need to match for an initializer with known type.
	if spec, ok := parent.(*ast.ValueSpec); ok && spec.Type != nil {
		if slices.Contains(spec.Values, expr) {
			typ := info.TypeOf(spec.Type)
			return true, typ == nil || types.IsInterface(typ), false
		}
	}

	// Types do not need to match for index expressions.
	if ix, ok := parent.(*ast.IndexExpr); ok {
		if ix.Index == expr {
			typ := info.TypeOf(ix.X)
			if typ == nil {
				return true, true, false
			}
			m, _ := typeparams.CoreType(typ).(*types.Map)
			return true, m == nil || types.IsInterface(m.Key()), false
		}
	}

	// Types do not need to match for composite literal keys, values, or
	// fields.
	if kv, ok := parent.(*ast.KeyValueExpr); ok {
		var under types.Type
		if len(remaining) > 0 {
			if complit, ok := remaining[len(remaining)-1].(*ast.CompositeLit); ok {
				if typ := info.TypeOf(complit); typ != nil {
					// Unpointer to allow for pointers to slices or arrays, which are
					// permitted as the types of nested composite literals without a type
					// name.
					under = typesinternal.Unpointer(typeparams.CoreType(typ))
				}
			}
		}
		if kv.Key == expr { // M{expr: ...}: assign to map key
			m, _ := under.(*types.Map)
			return true, m == nil || types.IsInterface(m.Key()), false
		}
		if kv.Value == expr {
			switch under := under.(type) {
			case interface{ Elem() types.Type }: // T{...: expr}: assign to map/array/slice element
				return true, types.IsInterface(under.Elem()), false
			case *types.Struct: // Struct{k: expr}
				if id, _ := kv.Key.(*ast.Ident); id != nil {
					for field := range under.Fields() {
						if info.Uses[id] == field {
							return true, types.IsInterface(field.Type()), false
						}
					}
				}
			default:
				return true, true, false
			}
		}
	}
	if lit, ok := parent.(*ast.CompositeLit); ok {
		for i, v := range lit.Elts {
			if v == expr {
				typ := info.TypeOf(lit)
				if typ == nil {
					return true, true, false
				}
				// As in the KeyValueExpr case above, unpointer to handle pointers to
				// array/slice literals.
				under := typesinternal.Unpointer(typeparams.CoreType(typ))
				switch under := under.(type) {
				case interface{ Elem() types.Type }: // T{expr}: assign to map/array/slice element
					return true, types.IsInterface(under.Elem()), false
				case *types.Struct: // Struct{expr}: assign to unkeyed struct field
					if i < under.NumFields() {
						return true, types.IsInterface(under.Field(i).Type()), false
					}
				}
				return true, true, false
			}
		}
	}

	// Types do not need to match for values sent to a channel.
	if send, ok := parent.(*ast.SendStmt); ok {
		if send.Value == expr {
			typ := info.TypeOf(send.Chan)
			if typ == nil {
				return true, true, false
			}
			ch, _ := typeparams.CoreType(typ).(*types.Chan)
			return true, ch == nil || types.IsInterface(ch.Elem()), false
		}
	}

	// Types do not need to match for an argument to a call, unless the
	// corresponding parameter has type parameters, as in that case the
	// argument type may affect inference.
	if call, ok := parent.(*ast.CallExpr); ok {
		if _, ok := isConversion(info, call); ok {
			return false, false, false // redundant conversions are handled at the call site
		}
		// Ordinary call. Could be a call of a func, builtin, or function value.
		for i, arg := range call.Args {
			if arg == expr {
				typ := info.TypeOf(call.Fun)
				if typ == nil {
					return true, true, false
				}
				sig, _ := typeparams.CoreType(typ).(*types.Signature)
				if sig != nil {
					// Find the relevant parameter type, accounting for variadics.
					paramType := paramTypeAtIndex(sig, call, i)
					ifaceAssign := paramType == nil || types.IsInterface(paramType)
					affectsInference := false
					switch callee := typeutil.Callee(info, call).(type) {
					case *types.Builtin:
						// Consider this litmus test:
						//
						//   func f(x int64) any { return max(x) }
						//   func main() { fmt.Printf("%T", f(42)) }
						//
						// If we lose the implicit conversion from untyped int
						// to int64, the type inferred for the max(x) call changes,
						// resulting in a different dynamic behavior: it prints
						// int, not int64.
						//
						// Inferred result type affected:
						//    new
						//    complex, real, imag
						//    min, max
						//
						// Dynamic behavior change:
						//    append         -- dynamic type of append([]any(nil), x)[0]
						//    delete(m, x)   -- dynamic key type where m is map[any]unit
						//    panic          -- dynamic type of panic value
						//
						// Unaffected:
						//    recover
						//    make
						//    len, cap
						//    clear
						//    close
						//    copy
						//    print, println  -- only uses underlying types (?)
						//
						// The dynamic type cases are all covered by
						// the ifaceAssign logic.
						switch callee.Name() {
						case "new", "complex", "real", "imag", "min", "max":
							affectsInference = true
						}

					case *types.Func:
						// Only standalone (non-method) functions have type
						// parameters affected by the call arguments.
						if sig2 := callee.Signature(); sig2.Recv() == nil {
							originParamType := paramTypeAtIndex(sig2, call, i)
							affectsInference = originParamType == nil || new(typeparams.Free).Has(originParamType)
						}
					}
					return true, ifaceAssign, affectsInference
				}
			}
		}
	}

	return false, false, false
}

// paramTypeAtIndex returns the effective parameter type at the given argument
// index in call, if valid.
func paramTypeAtIndex(sig *types.Signature, call *ast.CallExpr, index int) types.Type {
	if plen := sig.Params().Len(); sig.Variadic() && index >= plen-1 && !call.Ellipsis.IsValid() {
		if s, ok := sig.Params().At(plen - 1).Type().(*types.Slice); ok {
			return s.Elem()
		}
	} else if index < plen {
		return sig.Params().At(index).Type()
	}
	return nil // ill typed
}

// exprContext returns the innermost parent->child expression nodes for the
// given outer-to-inner stack, after stripping parentheses, along with the
// remaining stack up to the parent node.
//
// If no such context exists, returns (nil, nil, nil).
func exprContext(stack []ast.Node) (remaining []ast.Node, parent ast.Node, expr ast.Expr) {
	expr, _ = stack[len(stack)-1].(ast.Expr)
	if expr == nil {
		return nil, nil, nil
	}
	i := len(stack) - 2
	for ; i >= 0; i-- {
		if pexpr, ok := stack[i].(*ast.ParenExpr); ok {
			expr = pexpr
		} else {
			parent = stack[i]
			break
		}
	}
	if parent == nil {
		return nil, nil, nil
	}
	// inv: i is the index of parent in the stack.
	return stack[:i], parent, expr
}

// isSelectionOperand reports whether the innermost node of stack is operand
// (x) of a selection x.f.
func isSelectionOperand(stack []ast.Node) bool {
	_, parent, expr := exprContext(stack)
	if parent == nil {
		return false
	}
	sel, ok := parent.(*ast.SelectorExpr)
	return ok && sel.X == expr
}

// A shadowMap records information about shadowing at any of the parameter's
// references within the callee decl.
//
// For each name shadowed at a reference to the parameter within the callee
// body, shadow map records the 1-based index of the callee decl parameter
// causing the shadowing, or -1, if the shadowing is not due to a callee decl.
// A value of zero (or missing) indicates no shadowing. By convention,
// self-shadowing is excluded from the map.
//
// For example, in the following callee
//
//	func f(a, b int) int {
//		c := 2 + b
//		return a + c
//	}
//
// the shadow map of a is {b: 2, c: -1}, because b is shadowed by the 2nd
// parameter. The shadow map of b is {a: 1}, because c is not shadowed at the
// use of b.
type shadowMap map[string]int

// add returns the [shadowMap] augmented by the set of names
// locally shadowed at the location of the reference in the callee
// (identified by the stack). The name of the reference itself is
// excluded.
//
// These shadowed names may not be used in a replacement expression
// for the reference.
func (s shadowMap) add(info *types.Info, paramIndexes map[types.Object]int, exclude string, stack []ast.Node) shadowMap {
	for _, n := range stack {
		if scope := scopeFor(info, n); scope != nil {
			for _, name := range scope.Names() {
				if name != exclude {
					if s == nil {
						s = make(shadowMap)
					}
					obj := scope.Lookup(name)
					if idx, ok := paramIndexes[obj]; ok {
						s[name] = idx + 1
					} else {
						s[name] = -1
					}
				}
			}
		}
	}
	return s
}

// fieldObjs returns a map of each types.Object defined by the given signature
// to its index in the parameter list. Parameters with missing or blank name
// are skipped.
func fieldObjs(sig *types.Signature) map[types.Object]int {
	m := make(map[types.Object]int)
	for i := range sig.Params().Len() {
		if p := sig.Params().At(i); p.Name() != "" && p.Name() != "_" {
			m[p] = i
		}
	}
	return m
}

func isField(obj types.Object) bool {
	if v, ok := obj.(*types.Var); ok && v.IsField() {
		return true
	}
	return false
}

func isMethod(obj types.Object) bool {
	if f, ok := obj.(*types.Func); ok && f.Type().(*types.Signature).Recv() != nil {
		return true
	}
	return false
}

// -- serialization --

var (
	_ gob.GobEncoder = (*Callee)(nil)
	_ gob.GobDecoder = (*Callee)(nil)
)

func (callee *Callee) GobEncode() ([]byte, error) {
	var out bytes.Buffer
	if err := gob.NewEncoder(&out).Encode(callee.impl); err != nil {
		return nil, err
	}
	return out.Bytes(), nil
}

func (callee *Callee) GobDecode(data []byte) error {
	return gob.NewDecoder(bytes.NewReader(data)).Decode(&callee.impl)
}


================================================
FILE: internal/refactor/inline/calleefx.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

// This file defines the analysis of callee effects.

import (
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/internal/typesinternal"
)

const (
	rinf = -1 //  R∞: arbitrary read from memory
	winf = -2 //  W∞: arbitrary write to memory (or unknown control)
)

// calleefx returns a list of parameter indices indicating the order
// in which parameters are first referenced during evaluation of the
// callee, relative both to each other and to other effects of the
// callee (if any), such as arbitrary reads (rinf) and arbitrary
// effects (winf), including unknown control flow. Each parameter
// that is referenced appears once in the list.
//
// For example, the effects list of this function:
//
//	func f(x, y, z int) int {
//	    return y + x + g() + z
//	}
//
// is [1 0 -2 2], indicating reads of y and x, followed by the unknown
// effects of the g() call, and finally the read of parameter z. This
// information is used during inlining to ascertain when it is safe
// for parameter references to be replaced by their corresponding
// argument expressions. Such substitutions are permitted only when
// they do not cause "write" operations (those with effects) to
// commute with "read" operations (those that have no effect but are
// not pure). Impure operations may be reordered with other impure
// operations, and pure operations may be reordered arbitrarily.
//
// The analysis ignores the effects of runtime panics, on the
// assumption that well-behaved programs shouldn't encounter them.
func calleefx(info *types.Info, body *ast.BlockStmt, paramInfos map[*types.Var]*paramInfo) []int {
	// This traversal analyzes the callee's statements (in syntax
	// form, though one could do better with SSA) to compute the
	// sequence of events of the following kinds:
	//
	// 1  read of a parameter variable.
	// 2. reads from other memory.
	// 3. writes to memory

	var effects []int // indices of parameters, or rinf/winf (-ve)
	seen := make(map[int]bool)
	effect := func(i int) {
		if !seen[i] {
			seen[i] = true
			effects = append(effects, i)
		}
	}

	// unknown is called for statements of unknown effects (or control).
	unknown := func() {
		effect(winf)

		// Ensure that all remaining parameters are "seen"
		// after we go into the unknown (unless they are
		// unreferenced by the function body). This lets us
		// not bother implementing the complete traversal into
		// control structures.
		//
		// TODO(adonovan): add them in a deterministic order.
		// (This is not a bug but determinism is good.)
		for _, pinfo := range paramInfos {
			if !pinfo.IsResult && len(pinfo.Refs) > 0 {
				effect(pinfo.Index)
			}
		}
	}

	var visitExpr func(n ast.Expr)
	var visitStmt func(n ast.Stmt) bool
	visitExpr = func(n ast.Expr) {
		switch n := n.(type) {
		case *ast.Ident:
			if v, ok := info.Uses[n].(*types.Var); ok && !v.IsField() {
				// Use of global?
				if v.Parent() == v.Pkg().Scope() {
					effect(rinf) // read global var
				}

				// Use of parameter?
				if pinfo, ok := paramInfos[v]; ok && !pinfo.IsResult {
					effect(pinfo.Index) // read parameter var
				}

				// Use of local variables is ok.
			}

		case *ast.BasicLit:
			// no effect

		case *ast.FuncLit:
			// A func literal has no read or write effect
			// until called, and (most) function calls are
			// considered to have arbitrary effects.
			// So, no effect.

		case *ast.CompositeLit:
			for _, elt := range n.Elts {
				visitExpr(elt) // note: visits KeyValueExpr
			}

		case *ast.ParenExpr:
			visitExpr(n.X)

		case *ast.SelectorExpr:
			if seln, ok := info.Selections[n]; ok {
				visitExpr(n.X)

				// See types.SelectionKind for background.
				switch seln.Kind() {
				case types.MethodExpr:
					// A method expression T.f acts like a
					// reference to a func decl,
					// so it doesn't read x until called.

				case types.MethodVal, types.FieldVal:
					// A field or method value selection x.f
					// reads x if the selection indirects a pointer.

					if indirectSelection(seln) {
						effect(rinf)
					}
				}
			} else {
				// qualified identifier: treat like unqualified
				visitExpr(n.Sel)
			}

		case *ast.IndexExpr:
			if tv := info.Types[n.Index]; tv.IsType() {
				// no effect (G[T] instantiation)
			} else {
				visitExpr(n.X)
				visitExpr(n.Index)
				switch tv.Type.Underlying().(type) {
				case *types.Slice, *types.Pointer: // []T, *[n]T (not string, [n]T)
					effect(rinf) // indirect read of slice/array element
				}
			}

		case *ast.IndexListExpr:
			// no effect (M[K,V] instantiation)

		case *ast.SliceExpr:
			visitExpr(n.X)
			visitExpr(n.Low)
			visitExpr(n.High)
			visitExpr(n.Max)

		case *ast.TypeAssertExpr:
			visitExpr(n.X)

		case *ast.CallExpr:
			if info.Types[n.Fun].IsType() {
				// conversion T(x)
				visitExpr(n.Args[0])
			} else {
				// call f(args)
				visitExpr(n.Fun)
				for i, arg := range n.Args {
					if i == 0 && info.Types[arg].IsType() {
						continue // new(T), make(T, n)
					}
					visitExpr(arg)
				}

				// The pure built-ins have no effects beyond
				// those of their operands (not even memory reads).
				// All other calls have unknown effects.
				if !typesinternal.CallsPureBuiltin(info, n) {
					unknown() // arbitrary effects
				}
			}

		case *ast.StarExpr:
			visitExpr(n.X)
			effect(rinf) // *ptr load or store depends on state of heap

		case *ast.UnaryExpr: // + - ! ^ & ~ <-
			visitExpr(n.X)
			if n.Op == token.ARROW {
				unknown() // effect: channel receive
			}

		case *ast.BinaryExpr:
			visitExpr(n.X)
			visitExpr(n.Y)

		case *ast.KeyValueExpr:
			visitExpr(n.Key) // may be a struct field
			visitExpr(n.Value)

		case *ast.BadExpr:
			// no effect

		case nil:
			// optional subtree

		default:
			// type syntax: unreachable given traversal
			panic(n)
		}
	}

	// visitStmt's result indicates the continuation:
	// false for return, true for the next statement.
	//
	// We could treat return as an unknown, but this way
	// yields definite effects for simple sequences like
	// {S1; S2; return}, so unreferenced parameters are
	// not spuriously added to the effects list, and thus
	// not spuriously disqualified from elimination.
	visitStmt = func(n ast.Stmt) bool {
		switch n := n.(type) {
		case *ast.DeclStmt:
			decl := n.Decl.(*ast.GenDecl)
			for _, spec := range decl.Specs {
				switch spec := spec.(type) {
				case *ast.ValueSpec:
					for _, v := range spec.Values {
						visitExpr(v)
					}

				case *ast.TypeSpec:
					// no effect
				}
			}

		case *ast.LabeledStmt:
			return visitStmt(n.Stmt)

		case *ast.ExprStmt:
			visitExpr(n.X)

		case *ast.SendStmt:
			visitExpr(n.Chan)
			visitExpr(n.Value)
			unknown() // effect: channel send

		case *ast.IncDecStmt:
			visitExpr(n.X)
			unknown() // effect: variable increment

		case *ast.AssignStmt:
			for _, lhs := range n.Lhs {
				visitExpr(lhs)
			}
			for _, rhs := range n.Rhs {
				visitExpr(rhs)
			}
			for _, lhs := range n.Lhs {
				id, _ := lhs.(*ast.Ident)
				if id != nil && id.Name == "_" {
					continue // blank assign has no effect
				}
				if n.Tok == token.DEFINE && id != nil && info.Defs[id] != nil {
					continue // new var declared by := has no effect
				}
				unknown() // assignment to existing var
				break
			}

		case *ast.GoStmt:
			visitExpr(n.Call.Fun)
			for _, arg := range n.Call.Args {
				visitExpr(arg)
			}
			unknown() // effect: create goroutine

		case *ast.DeferStmt:
			visitExpr(n.Call.Fun)
			for _, arg := range n.Call.Args {
				visitExpr(arg)
			}
			unknown() // effect: push defer

		case *ast.ReturnStmt:
			for _, res := range n.Results {
				visitExpr(res)
			}
			return false

		case *ast.BlockStmt:
			for _, stmt := range n.List {
				if !visitStmt(stmt) {
					return false
				}
			}

		case *ast.BranchStmt:
			unknown() // control flow

		case *ast.IfStmt:
			visitStmt(n.Init)
			visitExpr(n.Cond)
			unknown() // control flow

		case *ast.SwitchStmt:
			visitStmt(n.Init)
			visitExpr(n.Tag)
			unknown() // control flow

		case *ast.TypeSwitchStmt:
			visitStmt(n.Init)
			visitStmt(n.Assign)
			unknown() // control flow

		case *ast.SelectStmt:
			unknown() // control flow

		case *ast.ForStmt:
			visitStmt(n.Init)
			visitExpr(n.Cond)
			unknown() // control flow

		case *ast.RangeStmt:
			visitExpr(n.X)
			unknown() // control flow

		case *ast.EmptyStmt, *ast.BadStmt:
			// no effect

		case nil:
			// optional subtree

		default:
			panic(n)
		}
		return true
	}
	visitStmt(body)

	return effects
}


================================================
FILE: internal/refactor/inline/calleefx_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline_test

import (
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/refactor/inline"
)

// TestCalleeEffects is a unit test of the calleefx analysis.
func TestCalleeEffects(t *testing.T) {
	// Each callee must declare a function or method named f.
	const funcName = "f"

	var tests = []struct {
		descr  string
		callee string // Go source file (sans package decl) containing callee decl
		want   string // expected effects string (-1=R∞ -2=W∞)
	}{
		{
			"Assignments have unknown effects.",
			`func f(x, y int) { x = y }`,
			`[0 1 -2]`,
		},
		{
			"Reads from globals are impure.",
			`func f() { _ = g }; var g int`,
			`[-1]`,
		},
		{
			"Writes to globals have effects.",
			`func f() { g = 0 }; var g int`,
			`[-1 -2]`, // the -1 is spurious but benign
		},
		{
			"Blank assign has no effect.",
			`func f(x int) { _ = x }`,
			`[0]`,
		},
		{
			"Short decl of new var has has no effect.",
			`func f(x int) { y := x; _ = y }`,
			`[0]`,
		},
		{
			"Short decl of existing var (y) is an assignment.",
			`func f(x int) { y := x; y, z := 1, 2; _, _ = y, z }`,
			`[0 -2]`,
		},
		{
			"Unreferenced parameters are excluded.",
			`func f(x, y, z int) { _ = z + x }`,
			`[2 0]`,
		},
		{
			"Built-in len has no effect.",
			`func f(x, y string) { _ = len(y) + len(x) }`,
			`[1 0]`,
		},
		{
			"Built-in println has effects.",
			`func f(x, y int) { println(y, x) }`,
			`[1 0 -2]`,
		},
		{
			"Return has no effect, and no control successor.",
			`func f(x, y int) int { return x + y; panic(1) }`,
			`[0 1]`,
		},
		{
			"Loops (etc) have unknown effects.",
			`func f(x, y bool) { for x { _ = y } }`,
			`[0 -2 1]`,
		},
		{
			"Calls have unknown effects.",
			`func f(x, y int) { _, _, _ = x, g(), y }; func g() int`,
			`[0 -2 1]`,
		},
		{
			"Calls to some built-ins are pure.",
			`func f(x, y int) { _, _, _ = x, len("hi"), y }`,
			`[0 1]`,
		},
		{
			"Calls to some built-ins are pure (variant).",
			`func f(x, y int) { s := "hi"; _, _, _ = x, len(s), y; s = "bye" }`,
			`[0 1 -2]`,
		},
		{
			"Calls to some built-ins are pure (another variants).",
			`func f(x, y int) { s := "hi"; _, _, _ = x, len(s), y }`,
			`[0 1]`,
		},
		{
			"Reading a local var is impure but does not have effects.",
			`func f(x, y bool) { for x { _ = y } }`,
			`[0 -2 1]`,
		},
	}
	for _, test := range tests {
		t.Run(test.descr, func(t *testing.T) {
			fset := token.NewFileSet()
			mustParse := func(filename string, content any) *ast.File {
				f, err := parser.ParseFile(fset, filename, content, parser.ParseComments|parser.SkipObjectResolution)
				if err != nil {
					t.Fatalf("ParseFile: %v", err)
				}
				return f
			}

			// Parse callee file and find first func decl named f.
			calleeContent := "package p\n" + test.callee
			calleeFile := mustParse("callee.go", calleeContent)
			var decl *ast.FuncDecl
			for _, d := range calleeFile.Decls {
				if d, ok := d.(*ast.FuncDecl); ok && d.Name.Name == funcName {
					decl = d
					break
				}
			}
			if decl == nil {
				t.Fatalf("declaration of func %s not found: %s", funcName, test.callee)
			}

			info := &types.Info{
				Defs:         make(map[*ast.Ident]types.Object),
				Uses:         make(map[*ast.Ident]types.Object),
				Types:        make(map[ast.Expr]types.TypeAndValue),
				Implicits:    make(map[ast.Node]types.Object),
				Selections:   make(map[*ast.SelectorExpr]*types.Selection),
				Scopes:       make(map[ast.Node]*types.Scope),
				FileVersions: make(map[*ast.File]string),
			}
			conf := &types.Config{Error: func(err error) { t.Error(err) }}
			pkg, err := conf.Check("p", fset, []*ast.File{calleeFile}, info)
			if err != nil {
				t.Fatal(err)
			}

			callee, err := inline.AnalyzeCallee(t.Logf, fset, pkg, info, decl, []byte(calleeContent))
			if err != nil {
				t.Fatal(err)
			}
			if got := fmt.Sprint(callee.Effects()); got != test.want {
				t.Errorf("for effects of %s, got %s want %s",
					test.callee, got, test.want)
			}
		})
	}
}


================================================
FILE: internal/refactor/inline/doc.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package inline implements inlining of Go function calls.

The client provides information about the caller and callee,
including the source text, syntax tree, and type information, and
the inliner returns the modified source file for the caller, or an
error if the inlining operation is invalid (for example because the
function body refers to names that are inaccessible to the caller).

Although this interface demands more information from the client
than might seem necessary, it enables smoother integration with
existing batch and interactive tools that have their own ways of
managing the processes of reading, parsing, and type-checking
packages. In particular, this package does not assume that the
caller and callee belong to the same token.FileSet or
types.Importer realms.

There are many aspects to a function call. It is the only construct
that can simultaneously bind multiple variables of different
explicit types, with implicit assignment conversions. (Neither var
nor := declarations can do that.) It defines the scope of control
labels, of return statements, and of defer statements. Arguments
and results of function calls may be tuples even though tuples are
not first-class values in Go, and a tuple-valued call expression
may be "spread" across the argument list of a call or the operands
of a return statement. All these unique features mean that in the
general case, not everything that can be expressed by a function
call can be expressed without one.

So, in general, inlining consists of modifying a function or method
call expression f(a1, ..., an) so that the name of the function f
is replaced ("literalized") by a literal copy of the function
declaration, with free identifiers suitably modified to use the
locally appropriate identifiers or perhaps constant argument
values.

Inlining must not change the semantics of the call. Semantics
preservation is crucial for clients such as codebase maintenance
tools that automatically inline all calls to designated functions
on a large scale. Such tools must not introduce subtle behavior
changes. (Fully inlining a call is dynamically observable using
reflection over the call stack, but this exception to the rule is
explicitly allowed.)

In many cases it is possible to entirely replace ("reduce") the
call by a copy of the function's body in which parameters have been
replaced by arguments. The inliner supports a number of reduction
strategies, and we expect this set to grow. Nonetheless, sound
reduction is surprisingly tricky.

The inliner is in some ways like an optimizing compiler. A compiler
is considered correct if it doesn't change the meaning of the
program in translation from source language to target language. An
optimizing compiler exploits the particulars of the input to
generate better code, where "better" usually means more efficient.
When a case is found in which it emits suboptimal code, the
compiler is improved to recognize more cases, or more rules, and
more exceptions to rules; this process has no end. Inlining is
similar except that "better" code means tidier code. The baseline
translation (literalization) is correct, but there are endless
rules--and exceptions to rules--by which the output can be
improved.

The following section lists some of the challenges, and ways in
which they can be addressed.

  - All effects of the call argument expressions must be preserved,
    both in their number (they must not be eliminated or repeated),
    and in their order (both with respect to other arguments, and any
    effects in the callee function).

    This must be the case even if the corresponding parameters are
    never referenced, are referenced multiple times, referenced in
    a different order from the arguments, or referenced within a
    nested function that may be executed an arbitrary number of
    times.

    Currently, parameter replacement is not applied to arguments
    with effects, but with further analysis of the sequence of
    strict effects within the callee we could relax this constraint.

  - When not all parameters can be substituted by their arguments
    (e.g. due to possible effects), if the call appears in a
    statement context, the inliner may introduce a var declaration
    that declares the parameter variables (with the correct types)
    and assigns them to their corresponding argument values.
    The rest of the function body may then follow.
    For example, the call

    f(1, 2)

    to the function

    func f(x, y int32) { stmts }

    may be reduced to

    { var x, y int32 = 1, 2; stmts }.

    There are many reasons why this is not always possible. For
    example, true parameters are statically resolved in the same
    scope, and are dynamically assigned their arguments in
    parallel; but each spec in a var declaration is statically
    resolved in sequence and dynamically executed in sequence, so
    earlier parameters may shadow references in later ones.

  - Even an argument expression as simple as ptr.x may not be
    referentially transparent, because another argument may have the
    effect of changing the value of ptr.

    This constraint could be relaxed by some kind of alias or
    escape analysis that proves that ptr cannot be mutated during
    the call.

  - Although constants are referentially transparent, as a matter of
    style we do not wish to duplicate literals that are referenced
    multiple times in the body because this undoes proper factoring.
    Also, string literals may be arbitrarily large.

  - If the function body consists of statements other than just
    "return expr", in some contexts it may be syntactically
    impossible to reduce the call. Consider:

    if x := f(); cond { ... }

    Go has no equivalent to Lisp's progn or Rust's blocks,
    nor ML's let expressions (let param = arg in body);
    its closest equivalent is func(param){body}(arg).
    Reduction strategies must therefore consider the syntactic
    context of the call.

    In such situations we could work harder to extract a statement
    context for the call, by transforming it to:

    { x := f(); if cond { ... } }

  - Similarly, without the equivalent of Rust-style blocks and
    first-class tuples, there is no general way to reduce a call
    to a function such as

    func(params)(args)(results) { stmts; return expr }

    to an expression such as

    { var params = args; stmts; expr }

    or even a statement such as

    results = { var params = args; stmts; expr }

    Consequently the declaration and scope of the result variables,
    and the assignment and control-flow implications of the return
    statement, must be dealt with by cases.

  - A standalone call statement that calls a function whose body is
    "return expr" cannot be simply replaced by the body expression
    if it is not itself a call or channel receive expression; it is
    necessary to explicitly discard the result using "_ = expr".

    Similarly, if the body is a call expression, only calls to some
    built-in functions with no result (such as copy or panic) are
    permitted as statements, whereas others (such as append) return
    a result that must be used, even if just by discarding.

  - If a parameter or result variable is updated by an assignment
    within the function body, it cannot always be safely replaced
    by a variable in the caller. For example, given

    func f(a int) int { a++; return a }

    The call y = f(x) cannot be replaced by { x++; y = x } because
    this would change the value of the caller's variable x.
    Only if the caller is finished with x is this safe.

    A similar argument applies to parameter or result variables
    that escape: by eliminating a variable, inlining would change
    the identity of the variable that escapes.

  - If the function body uses 'defer' and the inlined call is not a
    tail-call, inlining may delay the deferred effects.

  - Because the scope of a control label is the entire function, a
    call cannot be reduced if the caller and callee have intersecting
    sets of control labels. (It is possible to α-rename any
    conflicting ones, but our colleagues building C++ refactoring
    tools report that, when tools must choose new identifiers, they
    generally do a poor job.)

  - Given

    func f() uint8 { return 0 }

    var x any = f()

    reducing the call to var x any = 0 is unsound because it
    discards the implicit conversion to uint8. We may need to make
    each argument-to-parameter conversion explicit if the types
    differ. Assignments to variadic parameters may need to
    explicitly construct a slice.

    An analogous problem applies to the implicit assignments in
    return statements:

    func g() any { return f() }

    Replacing the call f() with 0 would silently lose a
    conversion to uint8 and change the behavior of the program.

  - When inlining a call f(1, x, g()) where those parameters are
    unreferenced, we should be able to avoid evaluating 1 and x
    since they are pure and thus have no effect. But x may be the
    last reference to a local variable in the caller, so removing
    it would cause a compilation error. Parameter substitution must
    avoid making the caller's local variables unreferenced (or must
    be prepared to eliminate the declaration too---this is where an
    iterative framework for simplification would really help).

  - An expression such as s[i] may be valid if s and i are
    variables but invalid if either or both of them are constants.
    For example, a negative constant index s[-1] is always out of
    bounds, and even a non-negative constant index may be out of
    bounds depending on the particular string constant (e.g.
    "abc"[4]).

    So, if a parameter participates in any expression that is
    subject to additional compile-time checks when its operands are
    constant, it may be unsafe to substitute that parameter by a
    constant argument value (#62664).

More complex callee functions are inlinable with more elaborate and
invasive changes to the statements surrounding the call expression.

TODO(adonovan): future work:

  - Handle more of the above special cases by careful analysis,
    thoughtful factoring of the large design space, and thorough
    test coverage.

  - Compute precisely (not conservatively) when parameter
    substitution would remove the last reference to a caller local
    variable, and blank out the local instead of retreating from
    the substitution.

  - Afford the client more control such as a limit on the total
    increase in line count, or a refusal to inline using the
    general approach (replacing name by function literal). This
    could be achieved by returning metadata alongside the result
    and having the client conditionally discard the change.

  - Support inlining of generic functions, replacing type parameters
    by their instantiations.

  - Support inlining of calls to function literals ("closures").
    But note that the existing algorithm makes widespread assumptions
    that the callee is a package-level function or method.

  - Eliminate explicit conversions of "untyped" literals inserted
    conservatively when they are redundant. For example, the
    conversion int32(1) is redundant when this value is used only as a
    slice index; but it may be crucial if it is used in x := int32(1)
    as it changes the type of x, which may have further implications.
    The conversions may also be important to the falcon analysis.

  - Allow non-'go' build systems such as Bazel/Blaze a chance to
    decide whether an import is accessible using logic other than
    "/internal/" path segments. This could be achieved by returning
    the list of added import paths instead of a text diff.

  - Inlining a function from another module may change the
    effective version of the Go language spec that governs it. We
    should probably make the client responsible for rejecting
    attempts to inline from newer callees to older callers, since
    there's no way for this package to access module versions.

  - Use an alternative implementation of the import-organizing
    operation that doesn't require operating on a complete file
    (and reformatting). Then return the results in a higher-level
    form as a set of import additions and deletions plus a single
    diff that encloses the call expression. This interface could
    perhaps be implemented atop imports.Process by post-processing
    its result to obtain the abstract import changes and discarding
    its formatted output.
*/
package inline


================================================
FILE: internal/refactor/inline/escape.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
)

// escape implements a simple "address-taken" escape analysis. It
// calls f for each local variable that appears on the left side of an
// assignment (escapes=false) or has its address taken (escapes=true).
// The initialization of a variable by its declaration does not count
// as an assignment.
func escape(info *types.Info, root ast.Node, f func(v *types.Var, escapes bool)) {

	// lvalue is called for each address-taken expression or LHS of assignment.
	// Supported forms are: x, (x), x[i], x.f, *x, T{}.
	var lvalue func(e ast.Expr, escapes bool)
	lvalue = func(e ast.Expr, escapes bool) {
		switch e := e.(type) {
		case *ast.Ident:
			if v, ok := info.Uses[e].(*types.Var); ok {
				if !isPkgLevel(v) {
					f(v, escapes)
				}
			}
		case *ast.ParenExpr:
			lvalue(e.X, escapes)
		case *ast.IndexExpr:
			// TODO(adonovan): support generics without assuming e.X has a core type.
			// Consider:
			//
			// func Index[T interface{ [3]int | []int }](t T, i int) *int {
			//     return &t[i]
			// }
			//
			// We must traverse the normal terms and check
			// whether any of them is an array.
			//
			// We assume TypeOf returns non-nil.
			if _, ok := info.TypeOf(e.X).Underlying().(*types.Array); ok {
				lvalue(e.X, escapes) // &a[i] on array
			}
		case *ast.SelectorExpr:
			// We assume TypeOf returns non-nil.
			if _, ok := info.TypeOf(e.X).Underlying().(*types.Struct); ok {
				lvalue(e.X, escapes) // &s.f on struct
			}
		case *ast.StarExpr:
			// *ptr indirects an existing pointer
		case *ast.CompositeLit:
			// &T{...} creates a new variable
		default:
			panic(fmt.Sprintf("&x on %T", e)) // unreachable in well-typed code
		}
	}

	// Search function body for operations &x, x.f(), x++, and x = y
	// where x is a parameter. Each of these treats x as an address.
	ast.Inspect(root, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.UnaryExpr:
			if n.Op == token.AND {
				lvalue(n.X, true) // &x
			}

		case *ast.CallExpr:
			// implicit &x in method call x.f(),
			// where x has type T and method is (*T).f
			if sel, ok := n.Fun.(*ast.SelectorExpr); ok {
				if seln, ok := info.Selections[sel]; ok &&
					seln.Kind() == types.MethodVal &&
					isPointer(seln.Obj().Type().Underlying().(*types.Signature).Recv().Type()) {
					tArg, indirect := effectiveReceiver(seln)
					if !indirect && !isPointer(tArg) {
						lvalue(sel.X, true) // &x.f
					}
				}
			}

		case *ast.AssignStmt:
			for _, lhs := range n.Lhs {
				if id, ok := lhs.(*ast.Ident); ok &&
					info.Defs[id] != nil &&
					n.Tok == token.DEFINE {
					// declaration: doesn't count
				} else {
					lvalue(lhs, false)
				}
			}

		case *ast.IncDecStmt:
			lvalue(n.X, false)
		}
		return true
	})
}


================================================
FILE: internal/refactor/inline/everything_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline_test

import (
	"flag"
	"fmt"
	"go/ast"
	"go/parser"
	"go/types"
	"log"
	"os"
	"path/filepath"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/refactor/inline"
	"golang.org/x/tools/internal/testenv"
)

var packagesFlag = flag.String("packages", "", "set of packages for TestEverything")

// TestEverything invokes the inliner on every single call site in a
// given package. and checks that it produces either a reasonable
// error, or output that parses and type-checks.
//
// It does nothing during ordinary testing, but may be used to find
// inlining bugs in large corpora.
//
// Use this command to inline everything in golang.org/x/tools:
//
// $ go test ./internal/refactor/inline/ -run=Everything -packages=../../../
//
// And these commands to inline everything in the kubernetes repository:
//
// $ go test -c -o /tmp/everything ./internal/refactor/inline/
// $ (cd kubernetes && /tmp/everything -test.run=Everything -packages=./...)
//
// TODO(adonovan):
//   - report counters (number of attempts, failed AnalyzeCallee, failed
//     Inline, etc.)
//   - Make a pretty log of the entire output so that we can peruse it
//     for opportunities for systematic improvement.
func TestEverything(t *testing.T) {
	testenv.NeedsGoPackages(t)
	if testing.Short() {
		t.Skipf("skipping slow test in -short mode")
	}
	if *packagesFlag == "" {
		return
	}

	// Load this package plus dependencies from typed syntax.
	cfg := &packages.Config{
		Mode: packages.LoadAllSyntax,
		Env: append(os.Environ(),
			"GO111MODULES=on",
			"GOPATH=",
			"GOWORK=off",
			"GOPROXY=off"),
	}
	pkgs, err := packages.Load(cfg, *packagesFlag)
	if err != nil {
		t.Errorf("Load: %v", err)
	}
	// Report parse/type errors.
	// Also, build transitive dependency mapping.
	deps := make(map[string]*packages.Package) // key is PkgPath
	packages.Visit(pkgs, nil, func(pkg *packages.Package) {
		deps[pkg.Types.Path()] = pkg
		for _, err := range pkg.Errors {
			t.Fatal(err)
		}
	})

	// Memoize repeated calls for same file.
	fileContent := make(map[string][]byte)
	readFile := func(filename string) ([]byte, error) {
		content, ok := fileContent[filename]
		if !ok {
			var err error
			content, err = os.ReadFile(filename)
			if err != nil {
				return nil, err
			}
			fileContent[filename] = content
		}
		return content, nil
	}

	for _, callerPkg := range pkgs {
		// Find all static function calls in the package.
		for _, callerFile := range callerPkg.Syntax {
			noMutCheck := checkNoMutation(callerFile)
			ast.Inspect(callerFile, func(n ast.Node) bool {
				call, ok := n.(*ast.CallExpr)
				if !ok {
					return true
				}
				fn := typeutil.StaticCallee(callerPkg.TypesInfo, call)
				if fn == nil {
					return true
				}

				// Prepare caller info.
				callPosn := callerPkg.Fset.PositionFor(call.Lparen, false)
				callerContent, err := readFile(callPosn.Filename)
				if err != nil {
					t.Fatal(err)
				}
				caller := &inline.Caller{
					Fset:  callerPkg.Fset,
					Types: callerPkg.Types,
					Info:  callerPkg.TypesInfo,
					File:  callerFile,
					Call:  call,
				}

				// Analyze callee.
				calleePkg, ok := deps[fn.Pkg().Path()]
				if !ok {
					t.Fatalf("missing package for callee %v", fn)
				}
				calleePosn := callerPkg.Fset.PositionFor(fn.Pos(), false)
				calleeDecl, err := findFuncByPosition(calleePkg, calleePosn)
				if err != nil {
					t.Fatal(err)
				}
				calleeContent, err := readFile(calleePosn.Filename)
				if err != nil {
					t.Fatal(err)
				}

				// Create a subtest for each inlining operation.
				name := fmt.Sprintf("%s@%v", fn.Name(), filepath.Base(callPosn.String()))
				t.Run(name, func(t *testing.T) {
					// TODO(adonovan): add a panic handler.

					t.Logf("callee declared at %v",
						filepath.Base(calleePosn.String()))

					t.Logf("run this command to reproduce locally:\n$ gopls codeaction -kind=refactor.inline -exec -diff %s:#%d",
						callPosn.Filename, callPosn.Offset)

					callee, err := inline.AnalyzeCallee(
						t.Logf,
						calleePkg.Fset,
						calleePkg.Types,
						calleePkg.TypesInfo,
						calleeDecl,
						calleeContent)
					if err != nil {
						// Ignore the expected kinds of errors.
						for _, ignore := range []string{
							"has no body",
							"type parameters are not yet",
							"line directives",
							"cgo-generated",
						} {
							if strings.Contains(err.Error(), ignore) {
								return
							}
						}
						t.Fatalf("AnalyzeCallee: %v", err)
					}
					if err := checkTranscode(callee); err != nil {
						t.Fatal(err)
					}

					res, err := inline.Inline(caller, callee, &inline.Options{
						Logf: t.Logf,
					})
					if err != nil {
						// Write error to a log, but this ok.
						t.Log(err)
						return
					}

					got, err := applyEdits(caller.Types, caller.File.FileStart, callerContent, res.Edits)
					if err != nil {
						t.Fatalf("can't apply inliner edits: %v", err)
					}

					// Print the diff.
					t.Logf("Got diff:\n%s",
						diff.Unified("old", "new", string(callerContent), string(got)))

					// Parse and type-check the transformed source.
					f, err := parser.ParseFile(caller.Fset, callPosn.Filename, got, parser.SkipObjectResolution)
					if err != nil {
						t.Fatalf("transformed source does not parse: %v", err)
					}
					// Splice into original file list.
					syntax := slices.Clone(callerPkg.Syntax)
					for i := range callerPkg.Syntax {
						if syntax[i] == callerFile {
							syntax[i] = f
							break
						}
					}

					var typeErrors []string
					conf := &types.Config{
						Error: func(err error) {
							typeErrors = append(typeErrors, err.Error())
						},
						Importer: importerFunc(func(importPath string) (*types.Package, error) {
							// Note: deps is properly keyed by package path,
							// not import path, but we can't assume
							// Package.Imports[importPath] exists in the
							// case of newly added imports of indirect
							// dependencies. Seems not to matter to this test.
							dep, ok := deps[importPath]
							if ok {
								return dep.Types, nil
							}
							return nil, fmt.Errorf("missing package: %q", importPath)
						}),
					}
					if _, err := conf.Check("p", caller.Fset, syntax, nil); err != nil {
						t.Fatalf("transformed package has type errors:\n\n%s\n\nTransformed file:\n\n%s",
							strings.Join(typeErrors, "\n"),
							got)
					}
				})
				return true
			})
			noMutCheck()
		}
	}
	log.Printf("Analyzed %d packages", len(pkgs))
}

type importerFunc func(path string) (*types.Package, error)

func (f importerFunc) Import(path string) (*types.Package, error) {
	return f(path)
}


================================================
FILE: internal/refactor/inline/export_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

// This file opens back doors for testing.

func (callee *Callee) Effects() []int { return callee.impl.Effects }


================================================
FILE: internal/refactor/inline/falcon.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

// This file defines the callee side of the "fallible constant" analysis.

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/format"
	"go/token"
	"go/types"
	"strconv"
	"strings"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
)

// falconResult is the result of the analysis of the callee.
type falconResult struct {
	Types       []falconType // types for falcon constraint environment
	Constraints []string     // constraints (Go expressions) on values of fallible constants
}

// A falconType specifies the name and underlying type of a synthetic
// defined type for use in falcon constraints.
//
// Unique types from callee code are bijectively mapped onto falcon
// types so that constraints are independent of callee type
// information but preserve type equivalence classes.
//
// Fresh names are deliberately obscure to avoid shadowing even if a
// callee parameter has a name like "int" or "any".
type falconType struct {
	Name string
	Kind types.BasicKind // string/number/bool
}

// falcon identifies "fallible constant" expressions, which are
// expressions that may fail to compile if one or more of their
// operands is changed from non-constant to constant.
//
// Consider:
//
//	func sub(s string, i, j int) string { return s[i:j] }
//
// If parameters are replaced by constants, the compiler is
// required to perform these additional checks:
//
//   - if i is constant, 0 <= i.
//   - if s and i are constant, i <= len(s).
//   - ditto for j.
//   - if i and j are constant, i <= j.
//
// s[i:j] is thus a "fallible constant" expression dependent on {s, i,
// j}. Each falcon creates a set of conditional constraints across one
// or more parameter variables.
//
//   - When inlining a call such as sub("abc", -1, 2), the parameter i
//     cannot be eliminated by substitution as its argument value is
//     negative.
//
//   - When inlining sub("", 2, 1), all three parameters cannot be
//     simultaneously eliminated by substitution without violating i
//     <= len(s) and j <= len(s), but the parameters i and j could be
//     safely eliminated without s.
//
// Parameters that cannot be eliminated must remain non-constant,
// either in the form of a binding declaration:
//
//	{ var i int = -1; return "abc"[i:2] }
//
// or a parameter of a literalization:
//
//	func (i int) string { return "abc"[i:2] }(-1)
//
// These example expressions are obviously doomed to fail at run
// time, but in realistic cases such expressions are dominated by
// appropriate conditions that make them reachable only when safe:
//
//	if 0 <= i && i <= j && j <= len(s) { _ = s[i:j] }
//
// (In principle a more sophisticated inliner could entirely eliminate
// such unreachable blocks based on the condition being always-false
// for the given parameter substitution, but this is tricky to do safely
// because the type-checker considers only a single configuration.
// Consider: if runtime.GOOS == "linux" { ... }.)
//
// We believe this is an exhaustive list of "fallible constant" operations:
//
//   - switch z { case x: case y } 	// duplicate case values
//   - s[i], s[i:j], s[i:j:k]		// index out of bounds (0 <= i <= j <= k <= len(s))
//   - T{x: 0}				// index out of bounds, duplicate index
//   - x/y, x%y, x/=y, x%=y		// integer division by zero; minint/-1 overflow
//   - x+y, x-y, x*y			// arithmetic overflow
//   - x<<y				// shift out of range
//   - -x				// negation of minint
//   - T(x)				// value out of range
//
// The fundamental reason for this elaborate algorithm is that the
// "separate analysis" of callee and caller, as required when running
// in an environment such as unitchecker, means that there is no way
// for us to simply invoke the type checker on the combination of
// caller and callee code, as by the time we analyze the caller, we no
// longer have access to type information for the callee (and, in
// particular, any of its direct dependencies that are not direct
// dependencies of the caller). So, in effect, we are forced to map
// the problem in a neutral (callee-type-independent) constraint
// system that can be verified later.
func falcon(logf func(string, ...any), fset *token.FileSet, params map[*types.Var]*paramInfo, info *types.Info, decl *ast.FuncDecl) falconResult {

	st := &falconState{
		logf:   logf,
		fset:   fset,
		params: params,
		info:   info,
		decl:   decl,
	}

	// type mapping
	st.int = st.typename(types.Typ[types.Int])
	st.any = "interface{}" // don't use "any" as it may be shadowed
	for obj, info := range st.params {
		if isBasic(obj.Type(), types.IsConstType) {
			info.FalconType = st.typename(obj.Type())
		}
	}

	st.stmt(st.decl.Body)

	return st.result
}

type falconState struct {
	// inputs
	logf   func(string, ...any)
	fset   *token.FileSet
	params map[*types.Var]*paramInfo
	info   *types.Info
	decl   *ast.FuncDecl

	// working state
	int       string
	any       string
	typenames typeutil.Map

	result falconResult
}

// typename returns the name in the falcon constraint system
// of a given string/number/bool type t. Falcon types are
// specified directly in go/types data structures rather than
// by name, avoiding potential shadowing conflicts with
// confusing parameter names such as "int".
//
// Also, each distinct type (as determined by types.Identical)
// is mapped to a fresh type in the falcon system so that we
// can map the types in the callee code into a neutral form
// that does not depend on imports, allowing us to detect
// potential conflicts such as
//
//	map[any]{T1(1): 0, T2(1): 0}
//
// where T1=T2.
func (st *falconState) typename(t types.Type) string {
	name, ok := st.typenames.At(t).(string)
	if !ok {
		basic := t.Underlying().(*types.Basic)

		// That dot ۰ is an Arabic zero numeral U+06F0.
		// It is very unlikely to appear in a real program.
		// TODO(adonovan): use a non-heuristic solution.
		name = fmt.Sprintf("%s۰%d", basic, st.typenames.Len())
		st.typenames.Set(t, name)
		st.logf("falcon: emit type %s %s // %q", name, basic, t)
		st.result.Types = append(st.result.Types, falconType{
			Name: name,
			Kind: basic.Kind(),
		})
	}
	return name
}

// -- constraint emission --

// emit emits a Go expression that must have a legal type.
// In effect, we let the go/types constant folding algorithm
// do most of the heavy lifting (though it may be hard to
// believe from the complexity of this algorithm!).
func (st *falconState) emit(constraint ast.Expr) {
	var out strings.Builder
	if err := format.Node(&out, st.fset, constraint); err != nil {
		panic(err) // can't happen
	}
	syntax := out.String()
	st.logf("falcon: emit constraint %s", syntax)
	st.result.Constraints = append(st.result.Constraints, syntax)
}

// emitNonNegative emits an []T{}[index] constraint,
// which ensures index is non-negative if constant.
func (st *falconState) emitNonNegative(index ast.Expr) {
	st.emit(&ast.IndexExpr{
		X: &ast.CompositeLit{
			Type: &ast.ArrayType{
				Elt: makeIdent(st.int),
			},
		},
		Index: index,
	})
}

// emitMonotonic emits an []T{}[i:j] constraint,
// which ensures i <= j if both are constant.
func (st *falconState) emitMonotonic(i, j ast.Expr) {
	st.emit(&ast.SliceExpr{
		X: &ast.CompositeLit{
			Type: &ast.ArrayType{
				Elt: makeIdent(st.int),
			},
		},
		Low:  i,
		High: j,
	})
}

// emitUnique emits a T{elem1: 0, ... elemN: 0} constraint,
// which ensures that all constant elems are unique.
// T may be a map, slice, or array depending
// on the desired check semantics.
func (st *falconState) emitUnique(typ ast.Expr, elems []ast.Expr) {
	if len(elems) > 1 {
		var elts []ast.Expr
		for _, elem := range elems {
			elts = append(elts, &ast.KeyValueExpr{
				Key:   elem,
				Value: makeIntLit(0),
			})
		}
		st.emit(&ast.CompositeLit{
			Type: typ,
			Elts: elts,
		})
	}
}

// -- traversal --

// The traversal functions scan the callee body for expressions that
// are not constant but would become constant if the parameter vars
// were redeclared as constants, and emits for each one a constraint
// (a Go expression) with the property that it will not type-check
// (using types.CheckExpr) if the particular argument values are
// unsuitable.
//
// These constraints are checked by Inline with the actual
// constant argument values. Violations cause it to reject
// parameters as candidates for substitution.

func (st *falconState) stmt(s ast.Stmt) {
	ast.Inspect(s, func(n ast.Node) bool {
		switch n := n.(type) {
		case ast.Expr:
			_ = st.expr(n)
			return false // skip usual traversal

		case *ast.AssignStmt:
			switch n.Tok {
			case token.QUO_ASSIGN, token.REM_ASSIGN:
				// x /= y
				// Possible "integer division by zero"
				// Emit constraint: 1/y.
				_ = st.expr(n.Lhs[0])
				kY := st.expr(n.Rhs[0])
				if kY, ok := kY.(ast.Expr); ok {
					op := token.QUO
					if n.Tok == token.REM_ASSIGN {
						op = token.REM
					}
					st.emit(&ast.BinaryExpr{
						Op: op,
						X:  makeIntLit(1),
						Y:  kY,
					})
				}
				return false // skip usual traversal
			}

		case *ast.SwitchStmt:
			if n.Init != nil {
				st.stmt(n.Init)
			}
			tBool := types.Type(types.Typ[types.Bool])
			tagType := tBool // default: true
			if n.Tag != nil {
				st.expr(n.Tag)
				tagType = st.info.TypeOf(n.Tag)
			}

			// Possible "duplicate case value".
			// Emit constraint map[T]int{v1: 0, ..., vN:0}
			// to ensure all maybe-constant case values are unique
			// (unless switch tag is boolean, which is relaxed).
			var unique []ast.Expr
			for _, clause := range n.Body.List {
				clause := clause.(*ast.CaseClause)
				for _, caseval := range clause.List {
					if k := st.expr(caseval); k != nil {
						unique = append(unique, st.toExpr(k))
					}
				}
				for _, stmt := range clause.Body {
					st.stmt(stmt)
				}
			}
			if unique != nil && !types.Identical(tagType.Underlying(), tBool) {
				tname := st.any
				if !types.IsInterface(tagType) {
					tname = st.typename(tagType)
				}
				t := &ast.MapType{
					Key:   makeIdent(tname),
					Value: makeIdent(st.int),
				}
				st.emitUnique(t, unique)
			}
		}
		return true
	})
}

// fieldTypes visits the .Type of each field in the list.
func (st *falconState) fieldTypes(fields *ast.FieldList) {
	if fields != nil {
		for _, field := range fields.List {
			_ = st.expr(field.Type)
		}
	}
}

// expr visits the expression (or type) and returns a
// non-nil result if the expression is constant or would
// become constant if all suitable function parameters were
// redeclared as constants.
//
// If the expression is constant, st.expr returns its type
// and value (types.TypeAndValue). If the expression would
// become constant, st.expr returns an ast.Expr tree whose
// leaves are literals and parameter references, and whose
// interior nodes are operations that may become constant,
// such as -x, x+y, f(x), and T(x). We call these would-be
// constant expressions "fallible constants", since they may
// fail to type-check for some values of x, i, and j. (We
// refer to the non-nil cases collectively as "maybe
// constant", and the nil case as "definitely non-constant".)
//
// As a side effect, st.expr emits constraints for each
// fallible constant expression; this is its main purpose.
//
// Consequently, st.expr must visit the entire subtree so
// that all necessary constraints are emitted. It may not
// short-circuit the traversal when it encounters a constant
// subexpression as constants may contain arbitrary other
// syntax that may impose constraints. Consider (as always)
// this contrived but legal example of a type parameter (!)
// that contains statement syntax:
//
//	func f[T [unsafe.Sizeof(func() { stmts })]int]()
//
// There is no need to emit constraints for (e.g.) s[i] when s
// and i are already constants, because we know the expression
// is sound, but it is sometimes easier to emit these
// redundant constraints than to avoid them.
func (st *falconState) expr(e ast.Expr) (res any) { // = types.TypeAndValue | ast.Expr
	tv := st.info.Types[e]
	if tv.Value != nil {
		// A constant value overrides any other result.
		defer func() { res = tv }()
	}

	switch e := e.(type) {
	case *ast.Ident:
		if v, ok := st.info.Uses[e].(*types.Var); ok {
			if _, ok := st.params[v]; ok && isBasic(v.Type(), types.IsConstType) {
				return e // reference to constable parameter
			}
		}
		// (References to *types.Const are handled by the defer.)

	case *ast.BasicLit:
		// constant

	case *ast.ParenExpr:
		return st.expr(e.X)

	case *ast.FuncLit:
		_ = st.expr(e.Type)
		st.stmt(e.Body)
		// definitely non-constant

	case *ast.CompositeLit:
		// T{k: v, ...}, where T ∈ {array,*array,slice,map},
		// imposes a constraint that all constant k are
		// distinct and, for arrays [n]T, within range 0-n.
		//
		// Types matter, not just values. For example,
		// an interface-keyed map may contain keys
		// that are numerically equal so long as they
		// are of distinct types. For example:
		//
		//   type myint int
		//   map[any]bool{1: true, 1:        true} // error: duplicate key
		//   map[any]bool{1: true, int16(1): true} // ok
		//   map[any]bool{1: true, myint(1): true} // ok
		//
		// This can be asserted by emitting a
		// constraint of the form T{k1: 0, ..., kN: 0}.
		if e.Type != nil {
			_ = st.expr(e.Type)
		}
		t := types.Unalias(typeparams.Deref(tv.Type))
		ct := typeparams.CoreType(t)
		var mapKeys []ast.Expr // map key expressions; must be distinct if constant
		for _, elt := range e.Elts {
			if kv, ok := elt.(*ast.KeyValueExpr); ok {
				if is[*types.Map](ct) {
					if k := st.expr(kv.Key); k != nil {
						mapKeys = append(mapKeys, st.toExpr(k))
					}
				}
				_ = st.expr(kv.Value)
			} else {
				_ = st.expr(elt)
			}
		}
		if len(mapKeys) > 0 {
			// Inlining a map literal may replace variable key expressions by constants.
			// All such constants must have distinct values.
			// (Array and slice literals do not permit non-constant keys.)
			t := ct.(*types.Map)
			var typ ast.Expr
			if types.IsInterface(t.Key()) {
				typ = &ast.MapType{
					Key:   makeIdent(st.any),
					Value: makeIdent(st.int),
				}
			} else {
				typ = &ast.MapType{
					Key:   makeIdent(st.typename(t.Key())),
					Value: makeIdent(st.int),
				}
			}
			st.emitUnique(typ, mapKeys)
		}
		// definitely non-constant

	case *ast.SelectorExpr:
		_ = st.expr(e.X)
		_ = st.expr(e.Sel)
		// The defer is sufficient to handle
		// qualified identifiers (pkg.Const).
		// All other cases are definitely non-constant.

	case *ast.IndexExpr:
		if tv.IsType() {
			// type C[T]
			_ = st.expr(e.X)
			_ = st.expr(e.Index)
		} else {
			// term x[i]
			//
			// Constraints (if x is slice/string/array/*array, not map):
			// - i >= 0
			//     if i is a fallible constant
			// - i < len(x)
			//     if x is array/*array and
			//     i is a fallible constant;
			//  or if s is a string and both i,
			//     s are maybe-constants,
			//     but not both are constants.
			kX := st.expr(e.X)
			kI := st.expr(e.Index)
			if kI != nil && !is[*types.Map](st.info.TypeOf(e.X).Underlying()) {
				if kI, ok := kI.(ast.Expr); ok {
					st.emitNonNegative(kI)
				}
				// Emit constraint to check indices against known length.
				// TODO(adonovan): factor with SliceExpr logic.
				var x ast.Expr
				if kX != nil {
					// string
					x = st.toExpr(kX)
				} else if arr, ok := typeparams.CoreType(typeparams.Deref(st.info.TypeOf(e.X))).(*types.Array); ok {
					// array, *array
					x = &ast.CompositeLit{
						Type: &ast.ArrayType{
							Len: makeIntLit(arr.Len()),
							Elt: makeIdent(st.int),
						},
					}
				}
				if x != nil {
					st.emit(&ast.IndexExpr{
						X:     x,
						Index: st.toExpr(kI),
					})
				}
			}
		}
		// definitely non-constant

	case *ast.SliceExpr:
		// x[low:high:max]
		//
		// Emit non-negative constraints for each index,
		// plus low <= high <= max <= len(x)
		// for each pair that are maybe-constant
		// but not definitely constant.

		kX := st.expr(e.X)
		var kLow, kHigh, kMax any
		if e.Low != nil {
			kLow = st.expr(e.Low)
			if kLow != nil {
				if kLow, ok := kLow.(ast.Expr); ok {
					st.emitNonNegative(kLow)
				}
			}
		}
		if e.High != nil {
			kHigh = st.expr(e.High)
			if kHigh != nil {
				if kHigh, ok := kHigh.(ast.Expr); ok {
					st.emitNonNegative(kHigh)
				}
				if kLow != nil {
					st.emitMonotonic(st.toExpr(kLow), st.toExpr(kHigh))
				}
			}
		}
		if e.Max != nil {
			kMax = st.expr(e.Max)
			if kMax != nil {
				if kMax, ok := kMax.(ast.Expr); ok {
					st.emitNonNegative(kMax)
				}
				if kHigh != nil {
					st.emitMonotonic(st.toExpr(kHigh), st.toExpr(kMax))
				}
			}
		}

		// Emit constraint to check indices against known length.
		var x ast.Expr
		if kX != nil {
			// string
			x = st.toExpr(kX)
		} else if arr, ok := typeparams.CoreType(typeparams.Deref(st.info.TypeOf(e.X))).(*types.Array); ok {
			// array, *array
			x = &ast.CompositeLit{
				Type: &ast.ArrayType{
					Len: makeIntLit(arr.Len()),
					Elt: makeIdent(st.int),
				},
			}
		}
		if x != nil {
			// Avoid slice[::max] if kHigh is nonconstant (nil).
			high, max := st.toExpr(kHigh), st.toExpr(kMax)
			if high == nil {
				high = max // => slice[:max:max]
			}
			st.emit(&ast.SliceExpr{
				X:    x,
				Low:  st.toExpr(kLow),
				High: high,
				Max:  max,
			})
		}
		// definitely non-constant

	case *ast.TypeAssertExpr:
		_ = st.expr(e.X)
		if e.Type != nil {
			_ = st.expr(e.Type)
		}

	case *ast.CallExpr:
		_ = st.expr(e.Fun)
		if tv, ok := st.info.Types[e.Fun]; ok && tv.IsType() {
			// conversion T(x)
			//
			// Possible "value out of range".
			kX := st.expr(e.Args[0])
			if kX != nil && isBasic(tv.Type, types.IsConstType) {
				conv := convert(makeIdent(st.typename(tv.Type)), st.toExpr(kX))
				if is[ast.Expr](kX) {
					st.emit(conv)
				}
				return conv
			}
			return nil // definitely non-constant
		}

		// call f(x)

		all := true // all args are possibly-constant
		kArgs := make([]ast.Expr, len(e.Args))
		for i, arg := range e.Args {
			if kArg := st.expr(arg); kArg != nil {
				kArgs[i] = st.toExpr(kArg)
			} else {
				all = false
			}
		}

		// Calls to built-ins with fallibly constant arguments
		// may become constant. All other calls are either
		// constant or non-constant
		if id, ok := e.Fun.(*ast.Ident); ok && all && tv.Value == nil {
			if builtin, ok := st.info.Uses[id].(*types.Builtin); ok {
				switch builtin.Name() {
				case "len", "imag", "real", "complex", "min", "max":
					return &ast.CallExpr{
						Fun:      id,
						Args:     kArgs,
						Ellipsis: e.Ellipsis,
					}
				}
			}
		}

	case *ast.StarExpr: // *T, *ptr
		_ = st.expr(e.X)

	case *ast.UnaryExpr:
		// + - ! ^ & <- ~
		//
		// Possible "negation of minint".
		// Emit constraint: -x
		kX := st.expr(e.X)
		if kX != nil && !is[types.TypeAndValue](kX) {
			if e.Op == token.SUB {
				st.emit(&ast.UnaryExpr{
					Op: e.Op,
					X:  st.toExpr(kX),
				})
			}

			return &ast.UnaryExpr{
				Op: e.Op,
				X:  st.toExpr(kX),
			}
		}

	case *ast.BinaryExpr:
		kX := st.expr(e.X)
		kY := st.expr(e.Y)
		switch e.Op {
		case token.QUO, token.REM:
			// x/y, x%y
			//
			// Possible "integer division by zero" or
			// "minint / -1" overflow.
			// Emit constraint: x/y or 1/y
			if kY != nil {
				if kX == nil {
					kX = makeIntLit(1)
				}
				st.emit(&ast.BinaryExpr{
					Op: e.Op,
					X:  st.toExpr(kX),
					Y:  st.toExpr(kY),
				})
			}

		case token.ADD, token.SUB, token.MUL:
			// x+y, x-y, x*y
			//
			// Possible "arithmetic overflow".
			// Emit constraint: x+y
			if kX != nil && kY != nil {
				st.emit(&ast.BinaryExpr{
					Op: e.Op,
					X:  st.toExpr(kX),
					Y:  st.toExpr(kY),
				})
			}

		case token.SHL, token.SHR:
			// x << y, x >> y
			//
			// Possible "constant shift too large".
			// Either operand may be too large individually,
			// and they may be too large together.
			// Emit constraint:
			//    x << y (if both maybe-constant)
			//    x << 0 (if y is non-constant)
			//    1 << y (if x is non-constant)
			if kX != nil || kY != nil {
				x := st.toExpr(kX)
				if x == nil {
					x = makeIntLit(1)
				}
				y := st.toExpr(kY)
				if y == nil {
					y = makeIntLit(0)
				}
				st.emit(&ast.BinaryExpr{
					Op: e.Op,
					X:  x,
					Y:  y,
				})
			}

		case token.LSS, token.GTR, token.EQL, token.NEQ, token.LEQ, token.GEQ:
			// < > == != <= <=
			//
			// A "x cmp y" expression with constant operands x, y is
			// itself constant, but I can't see how a constant bool
			// could be fallible: the compiler doesn't reject duplicate
			// boolean cases in a switch, presumably because boolean
			// switches are less like n-way branches and more like
			// sequential if-else chains with possibly overlapping
			// conditions; and there is (sadly) no way to convert a
			// boolean constant to an int constant.
		}
		if kX != nil && kY != nil {
			return &ast.BinaryExpr{
				Op: e.Op,
				X:  st.toExpr(kX),
				Y:  st.toExpr(kY),
			}
		}

	// types
	//
	// We need to visit types (and even type parameters)
	// in order to reach all the places where things could go wrong:
	//
	// 	const (
	// 		s = ""
	// 		i = 0
	// 	)
	// 	type C[T [unsafe.Sizeof(func() { _ = s[i] })]int] bool

	case *ast.IndexListExpr:
		_ = st.expr(e.X)
		for _, expr := range e.Indices {
			_ = st.expr(expr)
		}

	case *ast.Ellipsis:
		if e.Elt != nil {
			_ = st.expr(e.Elt)
		}

	case *ast.ArrayType:
		if e.Len != nil {
			_ = st.expr(e.Len)
		}
		_ = st.expr(e.Elt)

	case *ast.StructType:
		st.fieldTypes(e.Fields)

	case *ast.FuncType:
		st.fieldTypes(e.TypeParams)
		st.fieldTypes(e.Params)
		st.fieldTypes(e.Results)

	case *ast.InterfaceType:
		st.fieldTypes(e.Methods)

	case *ast.MapType:
		_ = st.expr(e.Key)
		_ = st.expr(e.Value)

	case *ast.ChanType:
		_ = st.expr(e.Value)
	}
	return
}

// toExpr converts the result of visitExpr to a falcon expression.
// (We don't do this in visitExpr as we first need to discriminate
// constants from maybe-constants.)
func (st *falconState) toExpr(x any) ast.Expr {
	switch x := x.(type) {
	case nil:
		return nil

	case types.TypeAndValue:
		lit := makeLiteral(x.Value)
		if !isBasic(x.Type, types.IsUntyped) {
			// convert to "typed" type
			lit = &ast.CallExpr{
				Fun:  makeIdent(st.typename(x.Type)),
				Args: []ast.Expr{lit},
			}
		}
		return lit

	case ast.Expr:
		return x

	default:
		panic(x)
	}
}

func makeLiteral(v constant.Value) ast.Expr {
	switch v.Kind() {
	case constant.Bool:
		// Rather than refer to the true or false built-ins,
		// which could be shadowed by poorly chosen parameter
		// names, we use 0 == 0 for true and 0 != 0 for false.
		op := token.EQL
		if !constant.BoolVal(v) {
			op = token.NEQ
		}
		return &ast.BinaryExpr{
			Op: op,
			X:  makeIntLit(0),
			Y:  makeIntLit(0),
		}

	case constant.String:
		return &ast.BasicLit{
			Kind:  token.STRING,
			Value: v.ExactString(),
		}

	case constant.Int:
		return &ast.BasicLit{
			Kind:  token.INT,
			Value: v.ExactString(),
		}

	case constant.Float:
		return &ast.BasicLit{
			Kind:  token.FLOAT,
			Value: v.ExactString(),
		}

	case constant.Complex:
		// The components could be float or int.
		y := makeLiteral(constant.Imag(v))
		y.(*ast.BasicLit).Value += "i" // ugh
		if re := constant.Real(v); !consteq(re, kZeroInt) {
			// complex: x + yi
			y = &ast.BinaryExpr{
				Op: token.ADD,
				X:  makeLiteral(re),
				Y:  y,
			}
		}
		return y

	default:
		panic(v.Kind())
	}
}

func makeIntLit(x int64) *ast.BasicLit {
	return &ast.BasicLit{
		Kind:  token.INT,
		Value: strconv.FormatInt(x, 10),
	}
}

func isBasic(t types.Type, info types.BasicInfo) bool {
	basic, ok := t.Underlying().(*types.Basic)
	return ok && basic.Info()&info != 0
}


================================================
FILE: internal/refactor/inline/falcon_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline_test

import "testing"

// Testcases mostly come in pairs, of a success and a failure
// to substitute based on specific constant argument values.

func TestFalconStringIndex(t *testing.T) {
	runTests(t, []testcase{
		{
			"Non-negative string index.",
			`func f(i int) byte { return s[i] }; var s string`,
			`func _() { f(0) }`,
			`func _() { _ = s[0] }`,
		},
		{
			"Negative string index.",
			`func f(i int) byte { return s[i] }; var s string`,
			`func _() { f(-1) }`,
			`func _() {
	var i int = -1
	_ = s[i]
}`,
		},
		{
			"String index in range.",
			`func f(s string, i int) byte { return s[i] }`,
			`func _() { f("-", 0) }`,
			`func _() { _ = "-"[0] }`,
		},
		{
			"String index out of range.",
			`func f(s string, i int) byte { return s[i] }`,
			`func _() { f("-", 1) }`,
			`func _() {
	var (
		s string = "-"
		i int    = 1
	)
	_ = s[i]
}`,
		},
		{
			"Remove known prefix (OK)",
			`func f(s, prefix string) string { return s[:len(prefix)] }`,
			`func _() { f("", "") }`,
			`func _() { _ = ""[:len("")] }`,
		},
		{
			"Remove not-a-prefix (out of range)",
			`func f(s, prefix string) string { return s[:len(prefix)] }`,
			`func _() { f("", "pre") }`,
			`func _() {
	var s, prefix string = "", "pre"
	_ = s[:len(prefix)]
}`,
		},
	})
}

func TestFalconSliceIndices(t *testing.T) {
	runTests(t, []testcase{
		{
			"Monotonic (0<=i<=j) slice indices (len unknown).",
			`func f(i, j int) []int { return s[i:j] }; var s []int`,
			`func _() { f(0, 1) }`,
			`func _() { _ = s[0:1] }`,
		},
		{
			"Non-monotonic slice indices (len unknown).",
			`func f(i, j int) []int { return s[i:j] }; var s []int`,
			`func _() { f(1, 0) }`,
			`func _() {
	var i, j int = 1, 0
	_ = s[i:j]
}`,
		},
		{
			"Negative slice index.",
			`func f(i, j int) []int { return s[i:j] }; var s []int`,
			`func _() { f(-1, 1) }`,
			`func _() {
	var i, j int = -1, 1
	_ = s[i:j]
}`,
		},
	})
}

func TestFalconMapKeys(t *testing.T) {
	runTests(t, []testcase{
		{
			"Unique map keys (int)",
			`func f(x int) { _ = map[int]bool{1: true, x: true} }`,
			`func _() { f(2) }`,
			`func _() { _ = map[int]bool{1: true, 2: true} }`,
		},
		{
			"Duplicate map keys (int)",
			`func f(x int) { _ = map[int]bool{1: true, x: true} }`,
			`func _() { f(1) }`,
			`func _() {
	var x int = 1
	_ = map[int]bool{1: true, x: true}
}`,
		},
		{
			"Generic map keys",
			// We have to use a named map type here, because the substituter tries to
			// wrap the type expr in parens, which are not allowed around the type in
			// composite literal expressions.
			`type Map map[int]bool; func f[M Map](x int) { _ = M{1: true, x: true} }`,
			`func _() { f[Map](1) }`,
			`func _() {
	var x int = 1
	_ = Map{1: true, x: true}
}`,
		},
		{
			"Array keys", // not a map; shouldn't crash (golang/go$74393)
			`func f(x int) { _ = [2]int{1: 0} }`,
			`func _() { f(0) }`,
			`func _() { _ = [2]int{1: 0} }`,
		},
		{
			"Slice keys", // not a map; shouldn't crash (golang/go$74393)
			`func f(x int) { _ = []int{1: 0} }`,
			`func _() { f(0) }`,
			`func _() { _ = []int{1: 0} }`,
		},
		{
			"Unique map keys (varied built-in types)",
			`func f(x int16) { _ = map[any]bool{1: true, x: true} }`,
			`func _() { f(2) }`,
			`func _() { _ = map[any]bool{1: true, int16(2): true} }`,
		},
		{
			"Duplicate map keys (varied built-in types)",
			`func f(x int16) { _ = map[any]bool{1: true, x: true} }`,
			`func _() { f(1) }`,
			`func _() { _ = map[any]bool{1: true, int16(1): true} }`,
		},
		{
			"Unique map keys (varied user-defined types)",
			`func f(x myint) { _ = map[any]bool{1: true, x: true} }; type myint int`,
			`func _() { f(2) }`,
			`func _() { _ = map[any]bool{1: true, myint(2): true} }`,
		},
		{
			"Duplicate map keys (varied user-defined types)",
			`func f(x myint, y myint2) { _ = map[any]bool{x: true, y: true} }; type (myint int; myint2 int)`,
			`func _() { f(1, 1) }`,
			`func _() {
	var (
		x myint  = 1
		y myint2 = 1
	)
	_ = map[any]bool{x: true, y: true}
}`,
		},
		{
			"Duplicate map keys (user-defined alias to built-in)",
			`func f(x myint, y int) { _ = map[any]bool{x: true, y: true} }; type myint = int`,
			`func _() { f(1, 1) }`,
			`func _() {
	var (
		x myint = 1
		y int   = 1
	)
	_ = map[any]bool{x: true, y: true}
}`,
		},
	})
}

func TestFalconSwitchCases(t *testing.T) {
	runTests(t, []testcase{
		{
			"Unique switch cases (int).",
			`func f(x int) { switch 0 { case x: case 1: } }`,
			`func _() { f(2) }`,
			`func _() {
	switch 0 {
	case 2:
	case 1:
	}
}`,
		},
		{
			"Duplicate switch cases (int).",
			`func f(x int) { switch 0 { case x: case 1: } }`,
			`func _() { f(1) }`,
			`func _() {
	var x int = 1
	switch 0 {
	case x:
	case 1:
	}
}`,
		},
		{
			"Unique switch cases (varied built-in types).",
			`func f(x int) { switch any(nil) { case x: case int16(1): } }`,
			`func _() { f(2) }`,
			`func _() {
	switch any(nil) {
	case 2:
	case int16(1):
	}
}`,
		},
		{
			"Duplicate switch cases (varied built-in types).",
			`func f(x int) { switch any(nil) { case x: case int16(1): } }`,
			`func _() { f(1) }`,
			`func _() {
	switch any(nil) {
	case 1:
	case int16(1):
	}
}`,
		},
	})
}

func TestFalconDivision(t *testing.T) {
	runTests(t, []testcase{
		{
			"Division by two.",
			`func f(x, y int) int { return x / y }`,
			`func _() { f(1, 2) }`,
			`func _() { _ = 1 / 2 }`,
		},
		{
			"Division by zero.",
			`func f(x, y int) int { return x / y }`,
			`func _() { f(1, 0) }`,
			`func _() {
	var x, y int = 1, 0
	_ = x / y
}`,
		},
		{
			"Division by two (statement).",
			`func f(x, y int) { x /= y }`,
			`func _() { f(1, 2) }`,
			`func _() {
	var x int = 1
	x /= 2
}`,
		},
		{
			"Division by zero (statement).",
			`func f(x, y int) { x /= y }`,
			`func _() { f(1, 0) }`,
			`func _() {
	var x, y int = 1, 0
	x /= y
}`,
		},
		{
			"Division of minint by two (ok).",
			`func f(x, y int32) { _ = x / y }`,
			`func _() { f(-0x80000000, 2) }`,
			`func _() { _ = int32(-0x80000000) / int32(2) }`,
		},
		{
			"Division of minint by -1 (overflow).",
			`func f(x, y int32) { _ = x / y }`,
			`func _() { f(-0x80000000, -1) }`,
			`func _() {
	var x, y int32 = -0x80000000, -1
	_ = x / y
}`,
		},
	})
}

func TestFalconMinusMinInt(t *testing.T) {
	runTests(t, []testcase{
		{
			"Negation of maxint.",
			`func f(x int32) int32 { return -x }`,
			`func _() { f(0x7fffffff) }`,
			`func _() { _ = -int32(0x7fffffff) }`,
		},
		{
			"Negation of minint.",
			`func f(x int32) int32 { return -x }`,
			`func _() { f(-0x80000000) }`,
			`func _() {
	var x int32 = -0x80000000
	_ = -x
}`,
		},
	})
}

func TestFalconArithmeticOverflow(t *testing.T) {
	runTests(t, []testcase{
		{
			"Addition without overflow.",
			`func f(x, y int32) int32 { return x + y }`,
			`func _() { f(100, 200) }`,
			`func _() { _ = int32(100) + int32(200) }`,
		},
		{
			"Addition with overflow.",
			`func f(x, y int32) int32 { return x + y }`,
			`func _() { f(1<<30, 1<<30) }`,
			`func _() {
	var x, y int32 = 1 << 30, 1 << 30
	_ = x + y
}`,
		},
		{
			"Conversion in range.",
			`func f(x int) int8 { return int8(x) }`,
			`func _() { f(123) }`,
			`func _() { _ = int8(123) }`,
		},
		{
			"Conversion out of range.",
			`func f(x int) int8 { return int8(x) }`,
			`func _() { f(456) }`,
			`func _() {
	var x int = 456
	_ = int8(x)
}`,
		},
	})
}

func TestFalconComplex(t *testing.T) {
	runTests(t, []testcase{
		{
			"Complex arithmetic (good).",
			`func f(re, im float64, z complex128) byte { return "x"[int(real(complex(re, im)*complex(re, -im)-z))] }`,
			`func _() { f(1, 2, 5+0i) }`,
			// The float64 conversions are excessively conservative here
			// but in general may affect the type of complex produced.
			`func _() { _ = "x"[int(real(complex(float64(1), float64(2))*complex(float64(1), -2)-(5+0i)))] }`,
		},
		{
			"Complex arithmetic (bad).",
			`func f(re, im float64, z complex128) byte { return "x"[int(real(complex(re, im)*complex(re, -im)-z))] }`,
			`func _() { f(1, 3, 5+0i) }`,
			`func _() {
	var (
		re, im float64    = 1, 3
		z      complex128 = 5 + 0i
	)
	_ = "x"[int(real(complex(re, im)*complex(re, -im)-z))]
}`,
		},
	})
}
func TestFalconMisc(t *testing.T) {
	runTests(t, []testcase{
		{
			"Compound constant expression (good).",
			`func f(x, y string, i, j int) byte { return x[i*len(y)+j] }`,
			`func _() { f("abc", "xy", 2, -3) }`,
			`func _() { _ = "abc"[2*len("xy")+-3] }`,
		},
		{
			"Compound constant expression (index out of range).",
			`func f(x, y string, i, j int) byte { return x[i*len(y)+j] }`,
			`func _() { f("abc", "xy", 4, -3) }`,
			`func _() {
	var (
		x, y string = "abc", "xy"
		i, j int    = 4, -3
	)
	_ = x[i*len(y)+j]
}`,
		},
		{
			"Constraints within nested functions (good).",
			`func f(x int) { _ = func() { _ = [1]int{}[x] } }`,
			`func _() { f(0) }`,
			`func _() { _ = func() { _ = [1]int{}[0] } }`,
		},
		{
			"Constraints within nested functions (bad).",
			`func f(x int) { _ = func() { _ = [1]int{}[x] } }`,
			`func _() { f(1) }`,
			`func _() {
	var x int = 1
	_ = func() { _ = [1]int{}[x] }
}`,
		},
		{
			"Falcon violation rejects only the constant arguments (x, z).",
			`func f(x, y, z string) string { return x[:2] + y + z[:2] }; var b string`,
			`func _() { f("a", b, "c") }`,
			`func _() {
	var x, z string = "a", "c"
	_ = x[:2] + b + z[:2]
}`,
		},
	})
}


================================================
FILE: internal/refactor/inline/inline.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/constant"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"maps"
	pathpkg "path"
	"reflect"
	"slices"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/types/typeutil"
	internalastutil "golang.org/x/tools/internal/astutil"
	"golang.org/x/tools/internal/astutil/free"
	"golang.org/x/tools/internal/packagepath"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/internal/versions"
)

// A Caller describes the function call and its enclosing context.
//
// The client is responsible for populating this struct and passing it to Inline.
type Caller struct {
	Fset  *token.FileSet
	Types *types.Package
	Info  *types.Info
	File  *ast.File
	Call  *ast.CallExpr

	// CountUses is an optional optimized computation of
	// the number of times pkgname appears in Info.Uses.
	CountUses func(pkgname *types.PkgName) int

	path          []ast.Node    // path from call to root of file syntax tree
	enclosingFunc *ast.FuncDecl // top-level function/method enclosing the call, if any
}

type logger = func(string, ...any)

// Options specifies parameters affecting the inliner algorithm.
// All fields are optional.
type Options struct {
	Logf          logger // log output function, records decision-making process
	IgnoreEffects bool   // ignore potential side effects of arguments (unsound)
}

// Result holds the result of code transformation.
type Result struct {
	Edits       []refactor.Edit // edits around CallExpr and imports
	Literalized bool            // chosen strategy replaced callee() with func(){...}()
	BindingDecl bool            // transformation added "var params = args" declaration
}

// Inline inlines the called function (callee) into the function call (caller)
// and returns the updated, formatted content of the caller source file.
//
// Inline does not mutate any public fields of Caller or Callee.
func Inline(caller *Caller, callee *Callee, opts *Options) (*Result, error) {
	copy := *opts // shallow copy
	opts = &copy
	// Set default options.
	if opts.Logf == nil {
		opts.Logf = func(string, ...any) {}
	}

	st := &state{
		caller: caller,
		callee: callee,
		opts:   opts,
	}
	return st.inline()
}

// state holds the working state of the inliner.
type state struct {
	caller *Caller
	callee *Callee
	opts   *Options
}

func (st *state) inline() (*Result, error) {
	logf, caller, callee := st.opts.Logf, st.caller, st.callee

	logf("inline %s @ %v",
		debugFormatNode(caller.Fset, caller.Call),
		caller.Fset.PositionFor(caller.Call.Lparen, false))

	if ast.IsGenerated(caller.File) {
		return nil, fmt.Errorf("cannot inline calls from generated files")
	}

	res, err := st.inlineCall()
	if err != nil {
		return nil, err
	}

	// Replace the call (or some node that encloses it) by new syntax.
	assert(res.old != nil, "old is nil")
	assert(res.new != nil, "new is nil")

	// A single return operand inlined to a unary
	// expression context may need parens. Otherwise:
	//    func two() int { return 1+1 }
	//    print(-two())  =>  print(-1+1) // oops!
	//
	// Usually it is not necessary to insert ParenExprs
	// as the formatter is smart enough to insert them as
	// needed by the context. But the res.{old,new}
	// substitution is done by formatting res.new in isolation
	// and then splicing its text over res.old, so the
	// formatter doesn't see the parent node and cannot do
	// the right thing. (One solution would be to always
	// format the enclosing node of old, but that requires
	// non-lossy comment handling, #20744.)
	//
	// So, we must analyze the call's context
	// to see whether ambiguity is possible.
	// For example, if the context is x[y:z], then
	// the x subtree is subject to precedence ambiguity
	// (replacing x by p+q would give p+q[y:z] which is wrong)
	// but the y and z subtrees are safe.
	if new, ok := res.new.(ast.Expr); ok {
		parent := caller.path[slices.Index(caller.path, res.old)+1]
		res.new = internalastutil.MaybeParenthesize(parent, res.old.(ast.Expr), new)
	}

	// Some reduction strategies return a new block holding the
	// callee's statements. The block's braces may be elided when
	// there is no conflict between names declared in the block
	// with those declared by the parent block, and no risk of
	// a caller's goto jumping forward across a declaration.
	//
	// This elision is only safe when the ExprStmt is beneath a
	// BlockStmt, CaseClause.Body, or CommClause.Body;
	// (see "statement theory").
	//
	// The inlining analysis may have already determined that eliding braces is
	// safe. Otherwise, we analyze its safety here.
	elideBraces := res.elideBraces
	if !elideBraces {
		if newBlock, ok := res.new.(*ast.BlockStmt); ok {
			i := slices.Index(caller.path, res.old)
			parent := caller.path[i+1]
			var body []ast.Stmt
			switch parent := parent.(type) {
			case *ast.BlockStmt:
				body = parent.List
			case *ast.CommClause:
				body = parent.Body
			case *ast.CaseClause:
				body = parent.Body
			}
			if body != nil {
				callerNames := declares(body)

				// If BlockStmt is a function body,
				// include its receiver, params, and results.
				addFieldNames := func(fields *ast.FieldList) {
					if fields != nil {
						for _, field := range fields.List {
							for _, id := range field.Names {
								callerNames[id.Name] = true
							}
						}
					}
				}
				switch f := caller.path[i+2].(type) {
				case *ast.FuncDecl:
					addFieldNames(f.Recv)
					addFieldNames(f.Type.Params)
					addFieldNames(f.Type.Results)
				case *ast.FuncLit:
					addFieldNames(f.Type.Params)
					addFieldNames(f.Type.Results)
				}

				if len(callerLabels(caller.path)) > 0 {
					// TODO(adonovan): be more precise and reject
					// only forward gotos across the inlined block.
					logf("keeping block braces: caller uses control labels")
				} else if intersects(declares(newBlock.List), callerNames) {
					logf("keeping block braces: avoids name conflict")
				} else {
					elideBraces = true
				}
			}
		}
	}

	var edits []refactor.Edit

	// Format the cloned callee.
	{
		// TODO(adonovan): might it make more sense to use
		// callee.Fset when formatting res.new?
		// The new tree is a mix of (cloned) caller nodes for
		// the argument expressions and callee nodes for the
		// function body. In essence the question is: which
		// is more likely to have comments?
		// Usually the callee body will be larger and more
		// statement-heavy than the arguments, but a
		// strategy may widen the scope of the replacement
		// (res.old) from CallExpr to, say, its enclosing
		// block, so the caller nodes dominate.
		// Precise comment handling would make this a
		// non-issue. Formatting wouldn't really need a
		// FileSet at all.

		var out bytes.Buffer
		if elideBraces {
			for i, stmt := range res.new.(*ast.BlockStmt).List {
				if i > 0 {
					out.WriteByte('\n')
				}
				if err := format.Node(&out, caller.Fset, stmt); err != nil {
					return nil, err
				}
			}
		} else {
			if err := format.Node(&out, caller.Fset, res.new); err != nil {
				return nil, err
			}
		}

		edits = append(edits, refactor.Edit{
			Pos:     res.old.Pos(),
			End:     res.old.End(),
			NewText: out.Bytes(),
		})
	}

	// Add new imports.
	//
	// It's possible that not all are needed (e.g. for type names
	// that melted away), but we'll let the client (such as an
	// analysis driver) clean it up since it must remove unused
	// imports anyway.
	for _, imp := range res.newImports {
		// Check that the new imports are accessible.
		if !packagepath.CanImport(caller.Types.Path(), imp.path) {
			return nil, fmt.Errorf("can't inline function %v as its body refers to inaccessible package %q", callee, imp.path)
		}

		// We've already validated the import, so we call
		// AddImportEdits directly to compute the edit.
		name := ""
		if imp.explicit {
			name = imp.name
		}
		edits = append(edits, refactor.AddImportEdits(caller.File, name, imp.path)...)
	}

	literalized := false
	if call, ok := res.new.(*ast.CallExpr); ok && is[*ast.FuncLit](call.Fun) {
		literalized = true
	}

	// Delete imports referenced only by caller.Call.Fun.
	//
	// It's ambiguous to let the client (e.g. analysis driver)
	// remove unneeded imports in this case because it is common
	// to inlining a call from "dir1/a".F to "dir2/a".F, which
	// leaves two imports of packages named 'a', both providing a.F.
	//
	// However, the only two import deletion tools at our disposal
	// are astutil.DeleteNamedImport, which mutates the AST, and
	// refactor.Delete{Spec,Decl}, which need a Cursor. So we need
	// to reinvent the wheel here.
	for _, oldImport := range res.oldImports {
		spec := oldImport.spec

		// Include adjacent comments.
		pos := spec.Pos()
		if doc := spec.Doc; doc != nil {
			pos = doc.Pos()
		}
		end := spec.End()
		if doc := spec.Comment; doc != nil {
			end = doc.End()
		}

		// Find the enclosing import decl.
		// If it's paren-less, we must delete it too.
		for _, decl := range caller.File.Decls {
			decl, ok := decl.(*ast.GenDecl)
			if !(ok && decl.Tok == token.IMPORT) {
				break // stop at first non-import decl
			}
			if internalastutil.NodeContainsPos(decl, spec.Pos()) && !decl.Rparen.IsValid() {
				// Include adjacent comments.
				pos = decl.Pos()
				if doc := decl.Doc; doc != nil {
					pos = doc.Pos()
				}
				end = decl.End()
				break
			}
		}

		edits = append(edits, refactor.Edit{
			Pos: pos,
			End: end,
		})
	}

	return &Result{
		Edits:       edits,
		Literalized: literalized,
		BindingDecl: res.bindingDecl,
	}, nil
}

// An oldImport is an import that will be deleted from the caller file.
type oldImport struct {
	pkgName *types.PkgName
	spec    *ast.ImportSpec
}

// A newImport is an import that will be added to the caller file.
type newImport struct {
	name     string
	path     string
	explicit bool // use name as ImportSpec.Name
}

// importState tracks information about imports.
type importState struct {
	logf       func(string, ...any)
	caller     *Caller
	importMap  map[string][]string // from package paths in the caller's file to local names
	newImports []newImport         // for references to free names in callee; to be added to the file
	oldImports []oldImport         // referenced only by caller.Call.Fun; to be removed from the file
}

// newImportState returns an importState with initial information about the caller's imports.
func newImportState(logf func(string, ...any), caller *Caller, callee *gobCallee) *importState {
	// For simplicity we ignore existing dot imports, so that a qualified
	// identifier (QI) in the callee is always represented by a QI in the caller,
	// allowing us to treat a QI like a selection on a package name.
	ist := &importState{
		logf:      logf,
		caller:    caller,
		importMap: make(map[string][]string),
	}

	// Provide an inefficient default implementation of CountUses.
	// (Ideally clients amortize this for the entire package.)
	countUses := caller.CountUses
	if countUses == nil {
		uses := make(map[*types.PkgName]int)
		for _, obj := range caller.Info.Uses {
			if pkgname, ok := obj.(*types.PkgName); ok {
				uses[pkgname]++
			}
		}
		countUses = func(pkgname *types.PkgName) int {
			return uses[pkgname]
		}
	}

	for _, imp := range caller.File.Imports {
		if pkgName, ok := importedPkgName(caller.Info, imp); ok &&
			pkgName.Name() != "." &&
			pkgName.Name() != "_" {

			// If the import's sole use is in caller.Call.Fun of the form p.F(...),
			// where p.F is a qualified identifier, the p import may not be
			// necessary.
			//
			// Only the qualified identifier case matters, as other references to
			// imported package names in the Call.Fun expression (e.g.
			// x.after(3*time.Second).f() or time.Second.String()) will remain after
			// inlining, as arguments.
			//
			// If that is the case, proactively check if any of the callee FreeObjs
			// need this import. Doing so eagerly simplifies the resulting logic.
			needed := true
			if sel, ok := ast.Unparen(caller.Call.Fun).(*ast.SelectorExpr); ok &&
				is[*ast.Ident](sel.X) &&
				caller.Info.Uses[sel.X.(*ast.Ident)] == pkgName &&
				countUses(pkgName) == 1 {
				needed = false // no longer needed by caller
				// Check to see if any of the inlined free objects need this package.
				for _, obj := range callee.FreeObjs {
					if obj.PkgPath == pkgName.Imported().Path() && obj.Shadow[pkgName.Name()] == 0 {
						needed = true // needed by callee
						break
					}
				}
			}

			// Exclude imports not needed by the caller or callee after inlining; the second
			// return value holds these.
			if needed {
				path := pkgName.Imported().Path()
				ist.importMap[path] = append(ist.importMap[path], pkgName.Name())
			} else {
				ist.oldImports = append(ist.oldImports, oldImport{pkgName: pkgName, spec: imp})
			}
		}
	}
	return ist
}

// importName finds an existing import name to use in a particular shadowing
// context. It is used to determine the set of new imports in
// localName, and is also used for writing out names in inlining
// strategies below.
func (i *importState) importName(pkgPath string, shadow shadowMap) string {
	for _, name := range i.importMap[pkgPath] {
		// Check that either the import preexisted, or that it was newly added
		// (no PkgName) but is not shadowed, either in the callee (shadows) or
		// caller (caller.lookup).
		if shadow[name] == 0 {
			found := i.caller.lookup(name)
			if is[*types.PkgName](found) || found == nil {
				return name
			}
		}
	}
	return ""
}

// findNewLocalName returns a new local package name to use in a particular shadowing context.
// It considers the existing local name used by the callee, or construct a new local name
// based on the package name.
func (i *importState) findNewLocalName(pkgName, calleePkgName string, shadow shadowMap) string {
	newlyAdded := func(name string) bool {
		return slices.ContainsFunc(i.newImports, func(n newImport) bool { return n.name == name })
	}

	// shadowedInCaller reports whether a candidate package name
	// already refers to a declaration in the caller.
	shadowedInCaller := func(name string) bool {
		obj := i.caller.lookup(name)
		if obj == nil {
			return false
		}
		// If obj will be removed, the name is available.
		return !slices.ContainsFunc(i.oldImports, func(o oldImport) bool { return o.pkgName == obj })
	}

	// import added by callee
	//
	// Try to preserve the local package name used by the callee first.
	//
	// If that is shadowed, choose a local package name based on last segment of
	// package path plus, if needed, a numeric suffix to ensure uniqueness.
	//
	// "init" is not a legal PkgName.
	if shadow[calleePkgName] == 0 && !shadowedInCaller(calleePkgName) && !newlyAdded(calleePkgName) && calleePkgName != "init" {
		return calleePkgName
	}

	base := pkgName
	name := base
	for n := 0; shadow[name] != 0 || shadowedInCaller(name) || newlyAdded(name) || name == "init"; n++ {
		name = fmt.Sprintf("%s%d", base, n)
	}

	return name
}

// localName returns the local name for a given imported package path,
// adding one if it doesn't exists.
func (i *importState) localName(pkgPath, pkgName, calleePkgName string, shadow shadowMap) string {
	// Does an import already exist that works in this shadowing context?
	if name := i.importName(pkgPath, shadow); name != "" {
		return name
	}

	name := i.findNewLocalName(pkgName, calleePkgName, shadow)
	i.logf("adding import %s %q", name, pkgPath)
	// Use explicit pkgname (out of necessity) when it differs from the declared name,
	// or (for good style) when it differs from base(pkgpath).
	i.newImports = append(i.newImports, newImport{
		name:     name,
		path:     pkgPath,
		explicit: name != pkgName || name != pathpkg.Base(pkgPath),
	})
	i.importMap[pkgPath] = append(i.importMap[pkgPath], name)
	return name
}

type inlineCallResult struct {
	newImports []newImport // to add
	oldImports []oldImport // to remove

	// If elideBraces is set, old is an ast.Stmt and new is an ast.BlockStmt to
	// be spliced in. This allows the inlining analysis to assert that inlining
	// the block is OK; if elideBraces is unset and old is an ast.Stmt and new is
	// an ast.BlockStmt, braces may still be elided if the post-processing
	// analysis determines that it is safe to do so.
	//
	// Ideally, it would not be necessary for the inlining analysis to "reach
	// through" to the post-processing pass in this way. Instead, inlining could
	// just set old to be an ast.BlockStmt and rewrite the entire BlockStmt, but
	// unfortunately in order to preserve comments, it is important that inlining
	// replace as little syntax as possible.
	elideBraces bool
	bindingDecl bool     // transformation inserted "var params = args" declaration
	old, new    ast.Node // e.g. replace call expr by callee function body expression
}

// inlineCall returns a pair of an old node (the call, or something
// enclosing it) and a new node (its replacement, which may be a
// combination of caller, callee, and new nodes), along with the set
// of new imports needed.
//
// TODO(adonovan): rethink the 'result' interface. The assumption of a
// one-to-one replacement seems fragile. One can easily imagine the
// transformation replacing the call and adding new variable
// declarations, for example, or replacing a call statement by zero or
// many statements.)
// NOTE(rfindley): we've sort-of done this, with the 'elideBraces' flag that
// allows inlining a statement list. However, due to loss of comments, more
// sophisticated rewrites are challenging.
//
// TODO(rfindley): see if we can reduce the amount of comment lossiness by
// using printer.CommentedNode, which has been useful elsewhere.
//
// TODO(rfindley): inlineCall is getting very long, and very stateful, making
// it very hard to read. The following refactoring may improve readability and
// maintainability:
//   - Rename 'state' to 'callsite', since that is what it encapsulates.
//   - Add results of pre-processing analysis into the callsite struct, such as
//     the effective importMap, new/old imports, arguments, etc. Essentially
//     anything that resulted from initial analysis of the call site, and which
//     may be useful to inlining strategies.
//   - Delegate this call site analysis to a constructor or initializer, such
//     as 'analyzeCallsite', so that it does not consume bandwidth in the
//     'inlineCall' logical flow.
//   - Once analyzeCallsite returns, the callsite is immutable, much in the
//     same way as the Callee and Caller are immutable.
//   - Decide on a standard interface for strategies (and substrategies), such
//     that they may be delegated to a separate method on callsite.
//
// In this way, the logical flow of inline call will clearly follow the
// following structure:
//  1. Analyze the call site.
//  2. Try strategies, in order, until one succeeds.
//  3. Process the results.
//
// If any expensive analysis may be avoided by earlier strategies, it can be
// encapsulated in its own type and passed to subsequent strategies.
func (st *state) inlineCall() (*inlineCallResult, error) {
	logf, caller, callee := st.opts.Logf, st.caller, &st.callee.impl

	checkInfoFields(caller.Info)

	// Inlining of dynamic calls is not currently supported,
	// even for local closure calls. (This would be a lot of work.)
	calleeSymbol := typeutil.StaticCallee(caller.Info, caller.Call)
	if calleeSymbol == nil {
		// e.g. interface method
		return nil, fmt.Errorf("cannot inline: not a static function call")
	}

	// Reject cross-package inlining if callee has
	// free references to unexported symbols.
	samePkg := caller.Types.Path() == callee.PkgPath
	if !samePkg && len(callee.Unexported) > 0 {
		return nil, fmt.Errorf("cannot inline call to %s because body refers to non-exported %s",
			callee.Name, callee.Unexported[0])
	}

	// Reject cross-file inlining if callee requires a newer dialect of Go (#75726).
	// (Versions default to types.Config.GoVersion, which is unset in many tests,
	// though should be populated by an analysis driver.)
	callerGoVersion := caller.Info.FileVersions[caller.File]
	if callerGoVersion != "" && callee.GoVersion != "" && versions.Before(callerGoVersion, callee.GoVersion) {
		return nil, fmt.Errorf("cannot inline call to %s (declared using %s) into a file using %s",
			callee.Name, callee.GoVersion, callerGoVersion)
	}

	// -- analyze callee's free references in caller context --

	// Compute syntax path enclosing Call, innermost first (Path[0]=Call),
	// and outermost enclosing function, if any.
	caller.path, _ = astutil.PathEnclosingInterval(caller.File, caller.Call.Pos(), caller.Call.End())
	for _, n := range caller.path {
		if decl, ok := n.(*ast.FuncDecl); ok {
			caller.enclosingFunc = decl
			break
		}
	}

	// If call is within a function, analyze all its
	// local vars for the "single assignment" property.
	// (Taking the address &v counts as a potential assignment.)
	var assign1 func(v *types.Var) bool // reports whether v a single-assignment local var
	{
		updatedLocals := make(map[*types.Var]bool)
		if caller.enclosingFunc != nil {
			escape(caller.Info, caller.enclosingFunc, func(v *types.Var, _ bool) {
				updatedLocals[v] = true
			})
			logf("multiple-assignment vars: %v", updatedLocals)
		}
		assign1 = func(v *types.Var) bool { return !updatedLocals[v] }
	}

	// Extract information about the caller's imports.
	istate := newImportState(logf, caller, callee)

	// Compute the renaming of the callee's free identifiers.
	objRenames, err := st.renameFreeObjs(istate)
	if err != nil {
		return nil, err
	}

	res := &inlineCallResult{
		newImports: istate.newImports,
		oldImports: istate.oldImports,
	}

	// Parse callee function declaration.
	calleeFset, calleeDecl, err := parseCompact(callee.Content)
	if err != nil {
		return nil, err // "can't happen"
	}

	// replaceCalleeID replaces an identifier in the callee. See [replacer] for
	// more detailed semantics.
	replaceCalleeID := func(offset int, repl ast.Expr, unpackVariadic bool) {
		path, id := findIdent(calleeDecl, calleeDecl.Pos()+token.Pos(offset))
		logf("- replace id %q @ #%d to %q", id.Name, offset, debugFormatNode(calleeFset, repl))
		// Replace f([]T{a, b, c}...) with f(a, b, c).
		if lit, ok := repl.(*ast.CompositeLit); ok && unpackVariadic && len(path) > 0 {
			if call, ok := last(path).(*ast.CallExpr); ok &&
				call.Ellipsis.IsValid() &&
				id == last(call.Args) {

				call.Args = append(call.Args[:len(call.Args)-1], lit.Elts...)
				call.Ellipsis = token.NoPos
				return
			}
		}
		replaceNode(calleeDecl, id, repl)
	}

	// Generate replacements for each free identifier.
	// (The same tree may be spliced in multiple times, resulting in a DAG.)
	for _, ref := range callee.FreeRefs {
		if repl := objRenames[ref.Object]; repl != nil {
			replaceCalleeID(ref.Offset, repl, false)
		}
	}

	// Gather the effective call arguments, including the receiver.
	// Later, elements will be eliminated (=> nil) by parameter substitution.
	args, err := st.arguments(caller, calleeDecl, assign1)
	if err != nil {
		return nil, err // e.g. implicit field selection cannot be made explicit
	}

	// Gather effective parameter tuple, including the receiver if any.
	// Simplify variadic parameters to slices (in all cases but one).
	var params []*parameter // including receiver; nil => parameter substituted
	{
		sig := calleeSymbol.Type().(*types.Signature)
		if sig.Recv() != nil {
			params = append(params, &parameter{
				obj:       sig.Recv(),
				fieldType: calleeDecl.Recv.List[0].Type,
				info:      callee.Params[0],
			})
		}

		// Flatten the list of syntactic types.
		var types []ast.Expr
		for _, field := range calleeDecl.Type.Params.List {
			if field.Names == nil {
				types = append(types, field.Type)
			} else {
				for range field.Names {
					types = append(types, field.Type)
				}
			}
		}

		for i := 0; i < sig.Params().Len(); i++ {
			params = append(params, &parameter{
				obj:       sig.Params().At(i),
				fieldType: types[i],
				info:      callee.Params[len(params)],
			})
		}

		// Variadic function?
		//
		// There are three possible types of call:
		// - ordinary f(a1, ..., aN)
		// - ellipsis f(a1, ..., slice...)
		// - spread   f(recv?, g()) where g() is a tuple.
		// The first two are desugared to non-variadic calls
		// with an ordinary slice parameter;
		// the third is tricky and cannot be reduced, and (if
		// a receiver is present) cannot even be literalized.
		// Fortunately it is vanishingly rare.
		//
		// TODO(adonovan): extract this to a function.
		if sig.Variadic() {
			lastParam := last(params)
			if len(args) > 0 && last(args).spread {
				// spread call to variadic: tricky
				lastParam.variadic = true
			} else {
				// ordinary/ellipsis call to variadic

				// simplify decl: func(T...) -> func([]T)
				lastParamField := last(calleeDecl.Type.Params.List)
				lastParamField.Type = &ast.ArrayType{
					Elt: lastParamField.Type.(*ast.Ellipsis).Elt,
				}

				if caller.Call.Ellipsis.IsValid() {
					// ellipsis call: f(slice...) -> f(slice)
					// nop
				} else {
					// ordinary call: f(a1, ... aN) -> f([]T{a1, ..., aN})
					//
					// Substitution of []T{...} in the callee body may lead to
					// g([]T{a1, ..., aN}...), which we simplify to g(a1, ..., an)
					// later; see replaceCalleeID.
					n := len(params) - 1
					ordinary, extra := args[:n], args[n:]
					var elts []ast.Expr
					freevars := make(map[string]bool)
					pure, effects := true, false
					for _, arg := range extra {
						elts = append(elts, arg.expr)
						pure = pure && arg.pure
						effects = effects || arg.effects
						maps.Copy(freevars, arg.freevars)
					}
					args = append(ordinary, &argument{
						expr: &ast.CompositeLit{
							Type: lastParamField.Type,
							Elts: elts,
						},
						typ:        lastParam.obj.Type(),
						constant:   nil,
						pure:       pure,
						effects:    effects,
						duplicable: false,
						freevars:   freevars,
						variadic:   true,
					})
				}
			}
		}
	}

	typeArgs := st.typeArguments(caller.Call)
	if len(typeArgs) != len(callee.TypeParams) {
		return nil, fmt.Errorf("cannot inline: type parameter inference is not yet supported")
	}
	if err := substituteTypeParams(logf, callee.TypeParams, typeArgs, params, replaceCalleeID); err != nil {
		return nil, err
	}

	// Log effective arguments.
	for i, arg := range args {
		logf("arg #%d: %s pure=%t effects=%t duplicable=%t free=%v type=%v",
			i, debugFormatNode(caller.Fset, arg.expr),
			arg.pure, arg.effects, arg.duplicable, arg.freevars, arg.typ)
	}

	// Note: computation below should be expressed in terms of
	// the args and params slices, not the raw material.

	// Perform parameter substitution.
	// May eliminate some elements of params/args.
	substitute(logf, caller, params, args, callee.Effects, callee.Falcon, replaceCalleeID)

	// Update the callee's signature syntax.
	updateCalleeParams(calleeDecl, params)

	// Create a var (param = arg; ...) decl for use by some strategies.
	bindingDecl := createBindingDecl(logf, caller, args, calleeDecl, callee.Results)

	var remainingArgs []ast.Expr
	for _, arg := range args {
		if arg != nil {
			remainingArgs = append(remainingArgs, arg.expr)
		}
	}

	// -- let the inlining strategies begin --
	//
	// When we commit to a strategy, we log a message of the form:
	//
	//   "strategy: reduce expr-context call to { return expr }"
	//
	// This is a terse way of saying:
	//
	//    we plan to reduce a call
	//    that appears in expression context
	//    to a function whose body is of the form { return expr }

	// TODO(adonovan): split this huge function into a sequence of
	// function calls with an error sentinel that means "try the
	// next strategy", and make sure each strategy writes to the
	// log the reason it didn't match.

	// Special case: eliminate a call to a function whose body is empty.
	// (=> callee has no results and caller is a statement.)
	//
	//    func f(params) {}
	//    f(args)
	//    => _, _ = args
	//
	if len(calleeDecl.Body.List) == 0 {
		logf("strategy: reduce call to empty body")

		// Evaluate the arguments for effects and delete the call entirely.
		// Note(golang/go#71486): stmt can be nil if the call is in a go or defer
		// statement.
		// TODO: discard go or defer statements as well.
		if stmt := callStmt(caller.path, false); stmt != nil {
			res.old = stmt
			if nargs := len(remainingArgs); nargs > 0 {
				// Emit "_, _ = args" to discard results.

				// TODO(adonovan): if args is the []T{a1, ..., an}
				// literal synthesized during variadic simplification,
				// consider unwrapping it to its (pure) elements.
				// Perhaps there's no harm doing this for any slice literal.

				// Make correction for spread calls
				// f(g()) or recv.f(g()) where g() is a tuple.
				if last := last(args); last != nil && last.spread {
					nspread := last.typ.(*types.Tuple).Len()
					if len(args) > 1 { // [recv, g()]
						// A single AssignStmt cannot discard both, so use a 2-spec var decl.
						res.new = &ast.GenDecl{
							Tok: token.VAR,
							Specs: []ast.Spec{
								&ast.ValueSpec{
									Names:  []*ast.Ident{makeIdent("_")},
									Values: []ast.Expr{args[0].expr},
								},
								&ast.ValueSpec{
									Names:  blanks[*ast.Ident](nspread),
									Values: []ast.Expr{args[1].expr},
								},
							},
						}
						return res, nil
					}

					// Sole argument is spread call.
					nargs = nspread
				}

				res.new = &ast.AssignStmt{
					Lhs: blanks[ast.Expr](nargs),
					Tok: token.ASSIGN,
					Rhs: remainingArgs,
				}

			} else {
				// No remaining arguments: delete call statement entirely
				res.new = &ast.EmptyStmt{}
			}
			return res, nil
		}
	}

	// If all parameters have been substituted and no result
	// variable is referenced, we don't need a binding decl.
	// This may enable better reduction strategies.
	allResultsUnreferenced := forall(callee.Results, func(i int, r *paramInfo) bool { return len(r.Refs) == 0 })
	needBindingDecl := !allResultsUnreferenced ||
		exists(params, func(i int, p *parameter) bool { return p != nil })

	// The two strategies below overlap for a tail call of {return exprs}:
	// The expr-context reduction is nice because it keeps the
	// caller's return stmt and merely switches its operand,
	// without introducing a new block, but it doesn't work with
	// implicit return conversions.
	//
	// TODO(adonovan): unify these cases more cleanly, allowing return-
	// operand replacement and implicit conversions, by adding
	// conversions around each return operand (if not a spread return).

	// Special case: call to { return exprs }.
	//
	// Reduces to:
	//	    { var (bindings); _, _ = exprs }
	//     or   _, _ = exprs
	//     or   expr
	//
	// If:
	// - the body is just "return expr" with trivial implicit conversions,
	//   or the caller's return type matches the callee's,
	// - all parameters and result vars can be eliminated
	//   or replaced by a binding decl,
	// then the call expression can be replaced by the
	// callee's body expression, suitably substituted.
	if len(calleeDecl.Body.List) == 1 &&
		is[*ast.ReturnStmt](calleeDecl.Body.List[0]) &&
		len(calleeDecl.Body.List[0].(*ast.ReturnStmt).Results) > 0 { // not a bare return
		results := calleeDecl.Body.List[0].(*ast.ReturnStmt).Results

		parent, grandparent := callContext(caller.path)

		// statement context
		if stmt, ok := parent.(*ast.ExprStmt); ok &&
			(!needBindingDecl || bindingDecl != nil) {
			logf("strategy: reduce stmt-context call to { return exprs }")
			clearPositions(calleeDecl.Body)

			if callee.ValidForCallStmt {
				logf("callee body is valid as statement")
				// Inv: len(results) == 1
				if !needBindingDecl {
					// Reduces to: expr
					res.old = caller.Call
					res.new = results[0]
				} else {
					// Reduces to: { var (bindings); expr }
					res.bindingDecl = true
					res.old = stmt
					res.new = &ast.BlockStmt{
						List: []ast.Stmt{
							bindingDecl.stmt,
							&ast.ExprStmt{X: results[0]},
						},
					}
				}
			} else {
				logf("callee body is not valid as statement")
				// The call is a standalone statement, but the
				// callee body is not suitable as a standalone statement
				// (f() or <-ch), explicitly discard the results:
				// Reduces to: _, _ = exprs
				discard := &ast.AssignStmt{
					Lhs: blanks[ast.Expr](callee.NumResults),
					Tok: token.ASSIGN,
					Rhs: results,
				}
				res.old = stmt
				if !needBindingDecl {
					// Reduces to: _, _ = exprs
					res.new = discard
				} else {
					// Reduces to: { var (bindings); _, _ = exprs }
					res.bindingDecl = true
					res.new = &ast.BlockStmt{
						List: []ast.Stmt{
							bindingDecl.stmt,
							discard,
						},
					}
				}
			}
			return res, nil
		}

		// Assignment context.
		//
		// If there is no binding decl, or if the binding decl declares no names,
		// an assignment a, b := f() can be reduced to a, b := x, y.
		if stmt, ok := parent.(*ast.AssignStmt); ok &&
			is[*ast.BlockStmt](grandparent) &&
			(!needBindingDecl || (bindingDecl != nil && len(bindingDecl.names) == 0)) {

			// Reduces to: { var (bindings); lhs... := rhs... }
			if newStmts, ok := st.assignStmts(stmt, results, istate.importName); ok {
				logf("strategy: reduce assign-context call to { return exprs }")

				clearPositions(calleeDecl.Body)

				block := &ast.BlockStmt{
					List: newStmts,
				}
				if needBindingDecl {
					res.bindingDecl = true
					block.List = prepend(bindingDecl.stmt, block.List...)
				}

				// assignStmts does not introduce new bindings, and replacing an
				// assignment only works if the replacement occurs in the same scope.
				// Therefore, we must ensure that braces are elided.
				res.elideBraces = true
				res.old = stmt
				res.new = block
				return res, nil
			}
		}

		// expression context
		if !needBindingDecl {
			clearPositions(calleeDecl.Body)

			anyNonTrivialReturns := hasNonTrivialReturn(callee.Returns)

			if callee.NumResults == 1 {
				logf("strategy: reduce expr-context call to { return expr }")
				// (includes some simple tail-calls)

				// Make implicit return conversion explicit.
				if anyNonTrivialReturns {
					results[0] = convert(calleeDecl.Type.Results.List[0].Type, results[0])
				}

				res.old = caller.Call
				res.new = results[0]
				return res, nil

			} else if !anyNonTrivialReturns {
				logf("strategy: reduce spread-context call to { return expr }")
				// There is no general way to reify conversions in a spread
				// return, hence the requirement above.
				//
				// TODO(adonovan): allow this reduction when no
				// conversion is required by the context.

				// The call returns multiple results but is
				// not a standalone call statement. It must
				// be the RHS of a spread assignment:
				//   var x, y  = f()
				//       x, y := f()
				//       x, y  = f()
				// or the sole argument to a spread call:
				//        printf(f())
				// or spread return statement:
				//        return f()
				res.old = parent
				switch context := parent.(type) {
				case *ast.AssignStmt:
					// Inv: the call must be in Rhs[0], not Lhs.
					assign := shallowCopy(context)
					assign.Rhs = results
					res.new = assign
				case *ast.ValueSpec:
					// Inv: the call must be in Values[0], not Names.
					spec := shallowCopy(context)
					spec.Values = results
					res.new = spec
				case *ast.CallExpr:
					// Inv: the call must be in Args[0], not Fun.
					call := shallowCopy(context)
					call.Args = results
					res.new = call
				case *ast.ReturnStmt:
					// Inv: the call must be Results[0].
					ret := shallowCopy(context)
					ret.Results = results
					res.new = ret
				default:
					return nil, fmt.Errorf("internal error: unexpected context %T for spread call", context)
				}
				return res, nil
			}
		}
	}

	// Special case: tail-call.
	//
	// Inlining:
	//         return f(args)
	// where:
	//         func f(params) (results) { body }
	// reduces to:
	//         { var (bindings); body }
	//         { body }
	// so long as:
	// - all parameters can be eliminated or replaced by a binding decl,
	// - call is a tail-call;
	// - all returns in body have trivial result conversions,
	//   or the caller's return type matches the callee's,
	// - there is no label conflict;
	// - no result variable is referenced by name,
	//   or implicitly by a bare return.
	//
	// The body may use defer, arbitrary control flow, and
	// multiple returns.
	//
	// TODO(adonovan): add a strategy for a 'void tail
	// call', i.e. a call statement prior to an (explicit
	// or implicit) return.
	parent, _ := callContext(caller.path)
	if ret, ok := parent.(*ast.ReturnStmt); ok &&
		len(ret.Results) == 1 &&
		tailCallSafeReturn(caller, calleeSymbol, callee) &&
		!callee.HasBareReturn &&
		(!needBindingDecl || bindingDecl != nil) &&
		!hasLabelConflict(caller.path, callee.Labels) &&
		allResultsUnreferenced {
		logf("strategy: reduce tail-call")
		body := calleeDecl.Body
		clearPositions(body)
		if needBindingDecl {
			res.bindingDecl = true
			body.List = prepend(bindingDecl.stmt, body.List...)
		}
		res.old = ret
		res.new = body
		return res, nil
	}

	// Special case: call to void function
	//
	// Inlining:
	//         f(args)
	// where:
	//	   func f(params) { stmts }
	// reduces to:
	//         { var (bindings); stmts }
	//         { stmts }
	// so long as:
	// - callee is a void function (no returns)
	// - callee does not use defer
	// - there is no label conflict between caller and callee
	// - all parameters and result vars can be eliminated
	//   or replaced by a binding decl,
	// - caller ExprStmt is in unrestricted statement context.
	if stmt := callStmt(caller.path, true); stmt != nil &&
		(!needBindingDecl || bindingDecl != nil) &&
		!callee.HasDefer &&
		!hasLabelConflict(caller.path, callee.Labels) &&
		len(callee.Returns) == 0 {
		logf("strategy: reduce stmt-context call to { stmts }")
		body := calleeDecl.Body
		var repl ast.Stmt = body
		clearPositions(repl)
		if needBindingDecl {
			body.List = prepend(bindingDecl.stmt, body.List...)
		}
		res.old = stmt
		res.new = repl
		return res, nil
	}

	// TODO(adonovan): parameterless call to { stmts; return expr }
	// from one of these contexts:
	//    x, y     = f()
	//    x, y    := f()
	//    var x, y = f()
	// =>
	//    var (x T1, y T2); { stmts; x, y = expr }
	//
	// Because the params are no longer declared simultaneously
	// we need to check that (for example) x ∉ freevars(T2),
	// in addition to the usual checks for arg/result conversions,
	// complex control, etc.
	// Also test cases where expr is an n-ary call (spread returns).

	// Literalization isn't quite infallible.
	// Consider a spread call to a method in which
	// no parameters are eliminated, e.g.
	// 	new(T).f(g())
	// where
	//  	func (recv *T) f(x, y int) { body }
	//  	func g() (int, int)
	// This would be literalized to:
	// 	func (recv *T, x, y int) { body }(new(T), g()),
	// which is not a valid argument list because g() must appear alone.
	// Reject this case for now.
	if len(args) == 2 && args[0] != nil && args[1] != nil && is[*types.Tuple](args[1].typ) {
		return nil, fmt.Errorf("can't yet inline spread call to method")
	}

	// Infallible general case: literalization.
	//
	//    func(params) { body }(args)
	//
	logf("strategy: literalization")
	funcLit := &ast.FuncLit{
		Type: calleeDecl.Type,
		Body: calleeDecl.Body,
	}
	// clear positions before prepending the binding decl below, since the
	// binding decl contains syntax from the caller and we must not mutate the
	// caller. (This was a prior bug.)
	clearPositions(funcLit)

	// Literalization can still make use of a binding
	// decl as it gives a more natural reading order:
	//
	//    func() { var params = args; body }()
	//
	// TODO(adonovan): relax the allResultsUnreferenced requirement
	// by adding a parameter-only (no named results) binding decl.
	if bindingDecl != nil && allResultsUnreferenced {
		funcLit.Type.Params.List = nil
		remainingArgs = nil
		res.bindingDecl = true
		funcLit.Body.List = prepend(bindingDecl.stmt, funcLit.Body.List...)
	}

	// Emit a new call to a function literal in place of
	// the callee name, with appropriate replacements.
	newCall := &ast.CallExpr{
		Fun:      funcLit,
		Ellipsis: token.NoPos, // f(slice...) is always simplified
		Args:     remainingArgs,
	}
	res.old = caller.Call
	res.new = newCall
	return res, nil
}

// renameFreeObjs computes the renaming of the callee's free identifiers.
// It returns a slice of names (identifiers or selector expressions) corresponding
// to the callee's free objects (gobCallee.FreeObjs).
func (st *state) renameFreeObjs(istate *importState) ([]ast.Expr, error) {
	caller, callee := st.caller, &st.callee.impl
	objRenames := make([]ast.Expr, len(callee.FreeObjs)) // nil => no change
	for i, obj := range callee.FreeObjs {
		// obj is a free object of the callee.
		//
		// Possible cases are:
		// - builtin function, type, or value (e.g. nil, zero)
		//   => check not shadowed in caller.
		// - package-level var/func/const/types
		//   => same package: check not shadowed in caller.
		//   => otherwise: import other package, form a qualified identifier.
		//      (Unexported cross-package references were rejected already.)
		// - type parameter
		//   => not yet supported
		// - pkgname
		//   => import other package and use its local name.
		//
		// There can be no free references to labels, fields, or methods.

		// Note that we must consider potential shadowing both
		// at the caller side (caller.lookup) and, when
		// choosing new PkgNames, within the callee (obj.shadow).

		var newName ast.Expr
		if obj.Kind == "pkgname" {
			// Use locally appropriate import, creating as needed.
			n := istate.localName(obj.PkgPath, obj.PkgName, obj.Name, obj.Shadow)
			newName = makeIdent(n) // imported package
		} else if !obj.ValidPos {
			// Built-in function, type, or value (e.g. nil, zero):
			// check not shadowed at caller.
			found := caller.lookup(obj.Name) // always finds something
			if found.Pos().IsValid() {
				return nil, fmt.Errorf("cannot inline, because the callee refers to built-in %q, which in the caller is shadowed by a %s (declared at line %d)",
					obj.Name, objectKind(found),
					caller.Fset.PositionFor(found.Pos(), false).Line)
			}

		} else {
			// Must be reference to package-level var/func/const/type,
			// since type parameters are not yet supported.
			qualify := false
			if obj.PkgPath == callee.PkgPath {
				// reference within callee package
				if caller.Types.Path() == callee.PkgPath {
					// Caller and callee are in same package.
					// Check caller has not shadowed the decl.
					//
					// This may fail if the callee is "fake", such as for signature
					// refactoring where the callee is modified to be a trivial wrapper
					// around the refactored signature.
					found := caller.lookup(obj.Name)
					if found != nil && !isPkgLevel(found) {
						return nil, fmt.Errorf("cannot inline, because the callee refers to %s %q, which in the caller is shadowed by a %s (declared at line %d)",
							obj.Kind, obj.Name,
							objectKind(found),
							caller.Fset.PositionFor(found.Pos(), false).Line)
					}
				} else {
					// Cross-package reference.
					qualify = true
				}
			} else {
				// Reference to a package-level declaration
				// in another package, without a qualified identifier:
				// it must be a dot import.
				qualify = true
			}

			// Form a qualified identifier, pkg.Name.
			if qualify {
				pkgName := istate.localName(obj.PkgPath, obj.PkgName, obj.PkgName, obj.Shadow)
				newName = &ast.SelectorExpr{
					X:   makeIdent(pkgName),
					Sel: makeIdent(obj.Name),
				}
			}
		}
		objRenames[i] = newName
	}
	return objRenames, nil
}

type argument struct {
	expr          ast.Expr
	typ           types.Type      // may be tuple for sole non-receiver arg in spread call
	constant      constant.Value  // value of argument if constant
	spread        bool            // final arg is call() assigned to multiple params
	pure          bool            // expr is pure (doesn't read variables)
	effects       bool            // expr has effects (updates variables)
	duplicable    bool            // expr may be duplicated
	freevars      map[string]bool // free names of expr
	variadic      bool            // is explicit []T{...} for eliminated variadic
	desugaredRecv bool            // is *recv or &recv, where operator was elided
}

// typeArguments returns the type arguments of the call.
// It only collects the arguments that are explicitly provided; it does
// not attempt type inference.
func (st *state) typeArguments(call *ast.CallExpr) []*argument {
	var exprs []ast.Expr
	switch d := ast.Unparen(call.Fun).(type) {
	case *ast.IndexExpr:
		exprs = []ast.Expr{d.Index}
	case *ast.IndexListExpr:
		exprs = d.Indices
	default:
		// No type  arguments
		return nil
	}
	var args []*argument
	for _, e := range exprs {
		arg := &argument{expr: e, freevars: freeVars(st.caller.Info, e)}
		// Wrap the instantiating type in parens when it's not an
		// ident or qualified ident to prevent "if x == struct{}"
		// parsing ambiguity, or "T(x)" where T = "*int" or "func()"
		// from misparsing.
		// TODO(adonovan): this fails in cases where parens are disallowed, such as
		// in the composite literal expression T{k: v}.
		if _, ok := arg.expr.(*ast.Ident); !ok {
			arg.expr = &ast.ParenExpr{X: arg.expr}
		}
		args = append(args, arg)
	}
	return args
}

// arguments returns the effective arguments of the call.
//
// If the receiver argument and parameter have
// different pointerness, make the "&" or "*" explicit.
//
// Also, if x.f() is shorthand for promoted method x.y.f(),
// make the .y explicit in T.f(x.y, ...).
//
// Beware that:
//
//   - a method can only be called through a selection, but only
//     the first of these two forms needs special treatment:
//
//     expr.f(args)     -> ([&*]expr, args)	MethodVal
//     T.f(recv, args)  -> (    expr, args)	MethodExpr
//
//   - the presence of a value in receiver-position in the call
//     is a property of the caller, not the callee. A method
//     (calleeDecl.Recv != nil) may be called like an ordinary
//     function.
//
//   - the types.Signatures seen by the caller (from
//     StaticCallee) and by the callee (from decl type)
//     differ in this case.
//
// In a spread call f(g()), the sole ordinary argument g(),
// always last in args, has a tuple type.
//
// We compute type-based predicates like pure, duplicable,
// freevars, etc, now, before we start modifying syntax.
func (st *state) arguments(caller *Caller, calleeDecl *ast.FuncDecl, assign1 func(*types.Var) bool) ([]*argument, error) {
	var args []*argument

	callArgs := caller.Call.Args
	if calleeDecl.Recv != nil {
		if len(st.callee.impl.TypeParams) > 0 {
			return nil, fmt.Errorf("cannot inline: generic methods not yet supported")
		}
		sel := ast.Unparen(caller.Call.Fun).(*ast.SelectorExpr)
		seln := caller.Info.Selections[sel]
		var recvArg ast.Expr
		switch seln.Kind() {
		case types.MethodVal: // recv.f(callArgs)
			recvArg = sel.X
		case types.MethodExpr: // T.f(recv, callArgs)
			recvArg = callArgs[0]
			callArgs = callArgs[1:]
		}
		if recvArg != nil {
			// Compute all the type-based predicates now,
			// before we start meddling with the syntax;
			// the meddling will update them.
			arg := &argument{
				expr:       recvArg,
				typ:        caller.Info.TypeOf(recvArg),
				constant:   caller.Info.Types[recvArg].Value,
				pure:       pure(caller.Info, assign1, recvArg),
				effects:    st.effects(caller.Info, recvArg),
				duplicable: duplicable(caller.Info, recvArg),
				freevars:   freeVars(caller.Info, recvArg),
			}
			recvArg = nil // prevent accidental use

			// Move receiver argument recv.f(args) to argument list f(&recv, args).
			args = append(args, arg)

			// Make field selections explicit (recv.f -> recv.y.f),
			// updating arg.{expr,typ}.
			indices := seln.Index()
			for _, index := range indices[:len(indices)-1] {
				fld := typeparams.CoreType(typeparams.Deref(arg.typ)).(*types.Struct).Field(index)
				if fld.Pkg() != caller.Types && !fld.Exported() {
					return nil, fmt.Errorf("in %s, implicit reference to unexported field .%s cannot be made explicit",
						debugFormatNode(caller.Fset, caller.Call.Fun),
						fld.Name())
				}
				if isPointer(arg.typ) {
					arg.pure = false // implicit *ptr operation => impure
				}
				arg.expr = &ast.SelectorExpr{
					X:   arg.expr,
					Sel: makeIdent(fld.Name()),
				}
				arg.typ = fld.Type()
				arg.duplicable = false
			}

			// Make * or & explicit.
			argIsPtr := isPointer(arg.typ)
			paramIsPtr := isPointer(seln.Obj().Type().Underlying().(*types.Signature).Recv().Type())
			if !argIsPtr && paramIsPtr {
				// &recv
				arg.expr = &ast.UnaryExpr{Op: token.AND, X: arg.expr}
				arg.typ = types.NewPointer(arg.typ)
				arg.desugaredRecv = true
			} else if argIsPtr && !paramIsPtr {
				// *recv
				arg.expr = &ast.StarExpr{X: arg.expr}
				arg.typ = typeparams.Deref(arg.typ)
				arg.duplicable = false
				arg.pure = false
				arg.desugaredRecv = true
			}
		}
	}
	for _, expr := range callArgs {
		tv := caller.Info.Types[expr]
		args = append(args, &argument{
			expr:       expr,
			typ:        tv.Type,
			constant:   tv.Value,
			spread:     is[*types.Tuple](tv.Type), // => last
			pure:       pure(caller.Info, assign1, expr),
			effects:    st.effects(caller.Info, expr),
			duplicable: duplicable(caller.Info, expr),
			freevars:   freeVars(caller.Info, expr),
		})
	}

	// Re-typecheck each constant argument expression in a neutral context.
	//
	// In a call such as func(int16){}(1), the type checker infers
	// the type "int16", not "untyped int", for the argument 1,
	// because it has incorporated information from the left-hand
	// side of the assignment implicit in parameter passing, but
	// of course in a different context, the expression 1 may have
	// a different type.
	//
	// So, we must use CheckExpr to recompute the type of the
	// argument in a neutral context to find its inherent type.
	// (This is arguably a bug in go/types, but I'm pretty certain
	// I requested it be this way long ago... -adonovan)
	//
	// This is only needed for constants. Other implicit
	// assignment conversions, such as unnamed-to-named struct or
	// chan to <-chan, do not result in the type-checker imposing
	// the LHS type on the RHS value.
	for _, arg := range args {
		if arg.constant == nil {
			continue
		}
		info := &types.Info{Types: make(map[ast.Expr]types.TypeAndValue)}
		if err := types.CheckExpr(caller.Fset, caller.Types, caller.Call.Pos(), arg.expr, info); err != nil {
			return nil, err
		}
		arg.typ = info.TypeOf(arg.expr)
	}

	return args, nil
}

type parameter struct {
	obj       *types.Var // parameter var from caller's signature
	fieldType ast.Expr   // syntax of type, from calleeDecl.Type.{Recv,Params}
	info      *paramInfo // information from AnalyzeCallee
	variadic  bool       // (final) parameter is unsimplified ...T
}

// A replacer replaces an identifier at the given offset in the callee.
// The replacement tree must not belong to the caller; use cloneNode as needed.
// If unpackVariadic is set, the replacement is a composite resulting from
// variadic elimination, and may be unpacked into variadic calls.
type replacer = func(offset int, repl ast.Expr, unpackVariadic bool)

// substituteTypeParams replaces type parameters in the callee with the corresponding type arguments
// from the call.
func substituteTypeParams(logf logger, typeParams []*paramInfo, typeArgs []*argument, params []*parameter, replace replacer) error {
	assert(len(typeParams) == len(typeArgs), "mismatched number of type params/args")
	for i, paramInfo := range typeParams {
		arg := typeArgs[i]
		// Perform a simplified, conservative shadow analysis: fail if there is any shadowing.
		for free := range arg.freevars {
			if paramInfo.Shadow[free] != 0 {
				return fmt.Errorf("cannot inline: type argument #%d (type parameter %s) is shadowed", i, paramInfo.Name)
			}
		}
		logf("replacing type param %s with %s", paramInfo.Name, debugFormatNode(token.NewFileSet(), arg.expr))
		for _, ref := range paramInfo.Refs {
			replace(ref.Offset, internalastutil.CloneNode(arg.expr), false)
		}
		// Also replace parameter field types.
		// TODO(jba): find a way to do this that is not so slow and clumsy.
		// Ideally, we'd walk each p.fieldType once, replacing all type params together.
		for _, p := range params {
			if id, ok := p.fieldType.(*ast.Ident); ok && id.Name == paramInfo.Name {
				p.fieldType = arg.expr
			} else {
				for _, id := range identsNamed(p.fieldType, paramInfo.Name) {
					replaceNode(p.fieldType, id, arg.expr)
				}
			}
		}
	}
	return nil
}

func identsNamed(n ast.Node, name string) []*ast.Ident {
	var ids []*ast.Ident
	ast.Inspect(n, func(n ast.Node) bool {
		if id, ok := n.(*ast.Ident); ok && id.Name == name {
			ids = append(ids, id)
		}
		return true
	})
	return ids
}

// substitute implements parameter elimination by substitution.
//
// It considers each parameter and its corresponding argument in turn
// and evaluate these conditions:
//
//   - the parameter is neither address-taken nor assigned;
//   - the argument is pure;
//   - if the parameter refcount is zero, the argument must
//     not contain the last use of a local var;
//   - if the parameter refcount is > 1, the argument must be duplicable;
//   - the argument (or types.Default(argument) if it's untyped) has
//     the same type as the parameter.
//
// If all conditions are met then the parameter can be substituted and
// each reference to it replaced by the argument. In that case, the
// replaceCalleeID function is called for each reference to the
// parameter, and is provided with its relative offset and replacement
// expression (argument), and the corresponding elements of params and
// args are replaced by nil.
func substitute(logf logger, caller *Caller, params []*parameter, args []*argument, effects []int, falcon falconResult, replace replacer) {
	// Inv:
	//  in        calls to     variadic, len(args) >= len(params)-1
	//  in spread calls to non-variadic, len(args) <  len(params)
	//  in spread calls to     variadic, len(args) <= len(params)
	// (In spread calls len(args) = 1, or 2 if call has receiver.)
	// Non-spread variadics have been simplified away already,
	// so the args[i] lookup is safe if we stop after the spread arg.
	assert(len(args) <= len(params), "too many arguments")

	// Collect candidates for substitution.
	//
	// An argument is a candidate if it is not otherwise rejected, and any free
	// variables that are shadowed only by other parameters.
	//
	// Therefore, substitution candidates are represented by a graph, where edges
	// lead from each argument to the other arguments that, if substituted, would
	// allow the argument to be substituted. We collect these edges in the
	// [substGraph]. Any node that is known not to be elided from the graph.
	// Arguments in this graph with no edges are substitutable independent of
	// other nodes, though they may be removed due to falcon or effects analysis.
	sg := make(substGraph)
next:
	for i, param := range params {
		arg := args[i]

		// Check argument against parameter.
		//
		// Beware: don't use types.Info on arg since
		// the syntax may be synthetic (not created by parser)
		// and thus lacking positions and types;
		// do it earlier (see pure/duplicable/freevars).

		if arg.spread {
			// spread => last argument, but not always last parameter
			logf("keeping param %q and following ones: argument %s is spread",
				param.info.Name, debugFormatNode(caller.Fset, arg.expr))
			return // give up
		}
		assert(!param.variadic, "unsimplified variadic parameter")
		if param.info.Escapes {
			logf("keeping param %q: escapes from callee", param.info.Name)
			continue
		}
		if param.info.Assigned {
			logf("keeping param %q: assigned by callee", param.info.Name)
			continue // callee needs the parameter variable
		}
		if len(param.info.Refs) > 1 && !arg.duplicable {
			logf("keeping param %q: argument is not duplicable", param.info.Name)
			continue // incorrect or poor style to duplicate an expression
		}
		if len(param.info.Refs) == 0 {
			if arg.effects {
				logf("keeping param %q: though unreferenced, it has effects", param.info.Name)
				continue
			}

			// If the caller is within a function body,
			// eliminating an unreferenced parameter might
			// remove the last reference to a caller local var.
			if caller.enclosingFunc != nil {
				for free := range arg.freevars {
					// TODO(rfindley): we can get this 100% right by looking for
					// references among other arguments which have non-zero references
					// within the callee.
					if v, ok := caller.lookup(free).(*types.Var); ok && within(v.Pos(), caller.enclosingFunc.Body) && !isUsedOutsideCall(caller, v) {

						// Check to see if the substituted var is used within other args
						// whose corresponding params ARE used in the callee
						usedElsewhere := func() bool {
							for i, param := range params {
								if i < len(args) && len(param.info.Refs) > 0 { // excludes original param
									for name := range args[i].freevars {
										if caller.lookup(name) == v {
											return true
										}
									}
								}
							}
							return false
						}
						if !usedElsewhere() {
							logf("keeping param %q: arg contains perhaps the last reference to caller local %v @ %v",
								param.info.Name, v, caller.Fset.PositionFor(v.Pos(), false))
							continue next
						}
					}
				}
			}
		}

		// Arg is a potential substitution candidate: analyze its shadowing.
		//
		// Consider inlining a call f(z, 1) to
		//
		// 	func f(x, y int) int { z := y; return x + y + z }
		//
		// we can't replace x in the body by z (or any
		// expression that has z as a free identifier) because there's an
		// intervening declaration of z that would shadow the caller's one.
		//
		// However, we *could* replace x in the body by y, as long as the y
		// parameter is also removed by substitution.

		sg[arg] = nil // Absent shadowing, the arg is substitutable.
		for free := range arg.freevars {
			switch s := param.info.Shadow[free]; {
			case s < 0:
				// Shadowed by a non-parameter symbol, so arg is not substitutable.
				delete(sg, arg)
			case s > 0:
				// Shadowed by a parameter; arg may be substitutable, if only shadowed
				// by other substitutable parameters.
				if s > len(args) {
					// Defensive: this should not happen in the current factoring, since
					// spread arguments are already handled.
					delete(sg, arg)
				}
				if edges, ok := sg[arg]; ok {
					sg[arg] = append(edges, args[s-1])
				}
			}
		}
	}

	// Process the initial state of the substitution graph.
	sg.prune()

	// Now we check various conditions on the substituted argument set as a
	// whole. These conditions reject substitution candidates, but since their
	// analysis depends on the full set of candidates, we do not process side
	// effects of their candidate rejection until after the analysis completes,
	// in a call to prune. After pruning, we must re-run the analysis to check
	// for additional rejections.
	//
	// Here's an example of that in practice:
	//
	// 	var a [3]int
	//
	// 	func falcon(x, y, z int) {
	// 		_ = x + a[y+z]
	// 	}
	//
	// 	func _() {
	// 		var y int
	// 		const x, z = 1, 2
	// 		falcon(y, x, z)
	// 	}
	//
	// In this example, arguments 0 and 1 are shadowed by each other's
	// corresponding parameter, and so each can be substituted only if they are
	// both substituted. But the fallible constant analysis finds a violated
	// constraint: x + z = 3, and so the constant array index would cause a
	// compile-time error if argument 1 (x) were substituted. Therefore,
	// following the falcon analysis, we must also prune argument 0.
	//
	// As far as I (rfindley) can tell, the falcon analysis should always succeed
	// after the first pass, as it's not possible for additional bindings to
	// cause new constraint failures. Nevertheless, we re-run it to be sure.
	//
	// However, the same cannot be said of the effects analysis, as demonstrated
	// by this example:
	//
	// 	func effects(w, x, y, z int) {
	// 		_ = x + w + y + z
	// 	}

	// 	func _() {
	// 		v := 0
	// 		w := func() int { v++; return 0 }
	// 		x := func() int { v++; return 0 }
	// 		y := func() int { v++; return 0 }
	// 		effects(x(), w(), y(), x()) //@ inline(re"effects", effects)
	// 	}
	//
	// In this example, arguments 0, 1, and 3 are related by the substitution
	// graph. The first effects analysis implies that arguments 0 and 1 must be
	// bound, and therefore argument 3 must be bound. But then a subsequent
	// effects analysis forces argument 2 to also be bound.

	// Reject constant arguments as substitution candidates if they cause
	// violation of falcon constraints.
	//
	// Keep redoing the analysis until we no longer reject additional arguments,
	// as the set of substituted parameters affects the falcon package.
	for checkFalconConstraints(logf, params, args, falcon, sg) {
		sg.prune()
	}

	// As a final step, introduce bindings to resolve any
	// evaluation order hazards. This must be done last, as
	// additional subsequent bindings could introduce new hazards.
	//
	// As with the falcon analysis, keep redoing the analysis until the no more
	// arguments are rejected.
	for resolveEffects(logf, args, effects, sg) {
		sg.prune()
	}

	// The remaining candidates are safe to substitute.
	for i, param := range params {
		if arg := args[i]; sg.has(arg) {

			// It is safe to substitute param and replace it with arg.
			// The formatter introduces parens as needed for precedence.
			//
			// Because arg.expr belongs to the caller,
			// we clone it before splicing it into the callee tree.
			logf("replacing parameter %q by argument %q",
				param.info.Name, debugFormatNode(caller.Fset, arg.expr))
			for _, ref := range param.info.Refs {
				// Apply any transformations necessary for this reference.
				argExpr := arg.expr

				// If the reference itself is being selected, and we applied desugaring
				// (an explicit &x or *x), we can undo that desugaring here as it is
				// not necessary for a selector. We don't need to check addressability
				// here because if we desugared, the receiver must have been
				// addressable.
				if ref.IsSelectionOperand && arg.desugaredRecv {
					switch e := argExpr.(type) {
					case *ast.UnaryExpr:
						argExpr = e.X
					case *ast.StarExpr:
						argExpr = e.X
					}
				}

				// If the reference requires exact type agreement between parameter and
				// argument, wrap the argument in an explicit conversion if
				// substitution might materially change its type. (We already did the
				// necessary shadowing check on the parameter type syntax.)
				//
				// The types must agree in any of these cases:
				// - the argument affects type inference;
				// - the reference's concrete type is assigned to an interface type;
				// - the reference is not an assignment, nor a trivial conversion of an untyped constant.
				//
				// In all other cases, no explicit conversion is necessary as either
				// the type does not matter, or must have already agreed for well-typed
				// code.
				//
				// This is only needed for substituted arguments. All other arguments
				// are given explicit types in either a binding decl or when using the
				// literalization strategy.
				//
				// If the types are identical, we can eliminate
				// redundant type conversions such as this:
				//
				// Callee:
				//    func f(i int32) { fmt.Println(i) }
				// Caller:
				//    func g() { f(int32(1)) }
				// Inlined as:
				//    func g() { fmt.Println(int32(int32(1)))
				//
				// Recall that non-trivial does not imply non-identical for constant
				// conversions; however, at this point state.arguments has already
				// re-typechecked the constant and set arg.type to its (possibly
				// "untyped") inherent type, so the conversion from untyped 1 to int32
				// is non-trivial even though both arg and param have identical types
				// (int32).
				needType := ref.AffectsInference ||
					(ref.Assignable && ref.IfaceAssignment && !param.info.IsInterface) ||
					(!ref.Assignable && !trivialConversion(arg.constant, arg.typ, param.obj.Type()))

				if needType &&
					!types.Identical(types.Default(arg.typ), param.obj.Type()) {

					// If arg.expr is already an interface call, strip it.
					if call, ok := argExpr.(*ast.CallExpr); ok && len(call.Args) == 1 {
						if typ, ok := isConversion(caller.Info, call); ok && isNonTypeParamInterface(typ) {
							argExpr = call.Args[0]
						}
					}

					argExpr = convert(param.fieldType, argExpr)
					logf("param %q (offset %d): adding explicit %s -> %s conversion around argument",
						param.info.Name, ref.Offset, arg.typ, param.obj.Type())
				}
				replace(ref.Offset, internalastutil.CloneNode(argExpr).(ast.Expr), arg.variadic)
			}
			params[i] = nil // substituted
			args[i] = nil   // substituted
		}
	}
}

// isConversion reports whether the given call is a type conversion, returning
// (operand, true) if so.
//
// If the call is not a conversion, it returns (nil, false).
func isConversion(info *types.Info, call *ast.CallExpr) (types.Type, bool) {
	if tv, ok := info.Types[call.Fun]; ok && tv.IsType() {
		return tv.Type, true
	}
	return nil, false
}

// isNonTypeParamInterface reports whether t is a non-type parameter interface
// type.
func isNonTypeParamInterface(t types.Type) bool {
	return !typeparams.IsTypeParam(t) && types.IsInterface(t)
}

// isUsedOutsideCall reports whether v is used outside of caller.Call, within
// the body of caller.enclosingFunc.
func isUsedOutsideCall(caller *Caller, v *types.Var) bool {
	used := false
	ast.Inspect(caller.enclosingFunc.Body, func(n ast.Node) bool {
		if n == caller.Call {
			return false
		}
		switch n := n.(type) {
		case *ast.Ident:
			if use := caller.Info.Uses[n]; use == v {
				used = true
			}
		case *ast.FuncType:
			// All params are used.
			for _, fld := range n.Params.List {
				for _, n := range fld.Names {
					if def := caller.Info.Defs[n]; def == v {
						used = true
					}
				}
			}
		}
		return !used // keep going until we find a use
	})
	return used
}

// checkFalconConstraints checks whether constant arguments
// are safe to substitute (e.g. s[i] -> ""[0] is not safe.)
//
// Any failed constraint causes us to reject all constant arguments as
// substitution candidates (by clearing args[i].substitution=false).
//
// TODO(adonovan): we could obtain a finer result rejecting only the
// freevars of each failed constraint, and processing constraints in
// order of increasing arity, but failures are quite rare.
func checkFalconConstraints(logf logger, params []*parameter, args []*argument, falcon falconResult, sg substGraph) bool {
	// Create a dummy package, as this is the only
	// way to create an environment for CheckExpr.
	pkg := types.NewPackage("falcon", "falcon")

	// Declare types used by constraints.
	for _, typ := range falcon.Types {
		logf("falcon env: type %s %s", typ.Name, types.Typ[typ.Kind])
		pkg.Scope().Insert(types.NewTypeName(token.NoPos, pkg, typ.Name, types.Typ[typ.Kind]))
	}

	// Declared constants and variables for parameters.
	nconst := 0
	for i, param := range params {
		name := param.info.Name
		if name == "" {
			continue // unreferenced
		}
		arg := args[i]
		if arg.constant != nil && sg.has(arg) && param.info.FalconType != "" {
			t := pkg.Scope().Lookup(param.info.FalconType).Type()
			pkg.Scope().Insert(types.NewConst(token.NoPos, pkg, name, t, arg.constant))
			logf("falcon env: const %s %s = %v", name, param.info.FalconType, arg.constant)
			nconst++
		} else {
			v := types.NewVar(token.NoPos, pkg, name, arg.typ)
			typesinternal.SetVarKind(v, typesinternal.PackageVar)
			pkg.Scope().Insert(v)
			logf("falcon env: var %s %s", name, arg.typ)
		}
	}
	if nconst == 0 {
		return false // nothing to do
	}

	// Parse and evaluate the constraints in the environment.
	fset := token.NewFileSet()
	removed := false
	for _, falcon := range falcon.Constraints {
		expr, err := parser.ParseExprFrom(fset, "falcon", falcon, 0)
		if err != nil {
			panic(fmt.Sprintf("failed to parse falcon constraint %s: %v", falcon, err))
		}
		if err := types.CheckExpr(fset, pkg, token.NoPos, expr, nil); err != nil {
			logf("falcon: constraint %s violated: %v", falcon, err)
			for j, arg := range args {
				if arg.constant != nil && sg.has(arg) {
					logf("keeping param %q due falcon violation", params[j].info.Name)
					removed = sg.remove(arg) || removed
				}
			}
			break
		}
		logf("falcon: constraint %s satisfied", falcon)
	}
	return removed
}

// resolveEffects marks arguments as non-substitutable to resolve
// hazards resulting from the callee evaluation order described by the
// effects list.
//
// To do this, each argument is categorized as a read (R), write (W),
// or pure. A hazard occurs when the order of evaluation of a W
// changes with respect to any R or W. Pure arguments can be
// effectively ignored, as they can be safely evaluated in any order.
//
// The callee effects list contains the index of each parameter in the
// order it is first evaluated during execution of the callee. In
// addition, the two special values R∞ and W∞ indicate the relative
// position of the callee's first non-parameter read and its first
// effects (or other unknown behavior).
// For example, the list [0 2 1 R∞ 3 W∞] for func(a, b, c, d)
// indicates that the callee referenced parameters a, c, and b,
// followed by an arbitrary read, then parameter d, and finally
// unknown behavior.
//
// When an argument is marked as not substitutable, we say that it is
// 'bound', in the sense that its evaluation occurs in a binding decl
// or literalized call. Such bindings always occur in the original
// callee parameter order.
//
// In this context, "resolving hazards" means binding arguments so
// that they are evaluated in a valid, hazard-free order. A trivial
// solution to this problem would be to bind all arguments, but of
// course that's not useful. The goal is to bind as few arguments as
// possible.
//
// The algorithm proceeds by inspecting arguments in reverse parameter
// order (right to left), preserving the invariant that every
// higher-ordered argument is either already substituted or does not
// need to be substituted. At each iteration, if there is an
// evaluation hazard in the callee effects relative to the current
// argument, the argument must be bound. Subsequently, if the argument
// is bound for any reason, each lower-ordered argument must also be
// bound if either the argument or lower-order argument is a
// W---otherwise the binding itself would introduce a hazard.
//
// Thus, after each iteration, there are no hazards relative to the
// current argument. Subsequent iterations cannot introduce hazards
// with that argument because they can result only in additional
// binding of lower-ordered arguments.
func resolveEffects(logf logger, args []*argument, effects []int, sg substGraph) bool {
	effectStr := func(effects bool, idx int) string {
		i := fmt.Sprint(idx)
		if idx == len(args) {
			i = "∞"
		}
		return string("RW"[btoi(effects)]) + i
	}
	removed := false
	for i := len(args) - 1; i >= 0; i-- {
		argi := args[i]
		if sg.has(argi) && !argi.pure {
			// i is not bound: check whether it must be bound due to hazards.
			idx := slices.Index(effects, i)
			if idx >= 0 {
				for _, j := range effects[:idx] {
					var (
						ji int  // effective param index
						jw bool // j is a write
					)
					if j == winf || j == rinf {
						jw = j == winf
						ji = len(args)
					} else {
						jw = args[j].effects
						ji = j
					}
					if ji > i && (jw || argi.effects) { // out of order evaluation
						logf("binding argument %s: preceded by %s",
							effectStr(argi.effects, i), effectStr(jw, ji))

						removed = sg.remove(argi) || removed
						break
					}
				}
			}
		}
		if !sg.has(argi) {
			for j := 0; j < i; j++ {
				argj := args[j]
				if argj.pure {
					continue
				}
				if (argi.effects || argj.effects) && sg.has(argj) {
					logf("binding argument %s: %s is bound",
						effectStr(argj.effects, j), effectStr(argi.effects, i))

					removed = sg.remove(argj) || removed
				}
			}
		}
	}
	return removed
}

// A substGraph is a directed graph representing arguments that may be
// substituted, provided all of their related arguments (or "dependencies") are
// also substituted. The candidates arguments for substitution are the keys in
// this graph, and the edges represent shadowing of free variables of the key
// by parameters corresponding to the dependency arguments.
//
// Any argument not present as a map key is known not to be substitutable. Some
// arguments may have edges leading to other arguments that are not present in
// the graph. In this case, those arguments also cannot be substituted, because
// they have free variables that are shadowed by parameters that cannot be
// substituted. Calling [substGraph.prune] removes these arguments from the
// graph.
//
// The 'prune' operation is not built into the 'remove' step both because
// analyses (falcon, effects) need local information about each argument
// independent of dependencies, and for the efficiency of pruning once en masse
// after each analysis.
type substGraph map[*argument][]*argument

// has reports whether arg is a candidate for substitution.
func (g substGraph) has(arg *argument) bool {
	_, ok := g[arg]
	return ok
}

// remove marks arg as not substitutable, reporting whether the arg was
// previously substitutable.
//
// remove does not have side effects on other arguments that may be
// unsubstitutable as a result of their dependency being removed.
// Call [substGraph.prune] to propagate these side effects, removing dependent
// arguments.
func (g substGraph) remove(arg *argument) bool {
	pre := len(g)
	delete(g, arg)
	return len(g) < pre
}

// prune updates the graph to remove any keys that reach other arguments not
// present in the graph.
func (g substGraph) prune() {
	// visit visits the forward transitive closure of arg and reports whether any
	// missing argument was encountered, removing all nodes on the path to it
	// from arg.
	//
	// The seen map is used for cycle breaking. In the presence of cycles, visit
	// may report a false positive for an intermediate argument. For example,
	// consider the following graph, where only a and b are candidates for
	// substitution (meaning, only a and b are present in the graph).
	//
	//   a ↔ b
	//   ↓
	//  [c]
	//
	// In this case, starting a visit from a, visit(b, seen) may report 'true',
	// because c has not yet been considered. For this reason, we must guarantee
	// that visit is called with an empty seen map at least once for each node.
	var visit func(*argument, map[*argument]unit) bool
	visit = func(arg *argument, seen map[*argument]unit) bool {
		deps, ok := g[arg]
		if !ok {
			return false
		}
		if _, ok := seen[arg]; !ok {
			seen[arg] = unit{}
			for _, dep := range deps {
				if !visit(dep, seen) {
					delete(g, arg)
					return false
				}
			}
		}
		return true
	}
	for arg := range g {
		// Remove any argument that is, or transitively depends upon,
		// an unsubstitutable argument.
		//
		// Each visitation gets a fresh cycle-breaking set.
		visit(arg, make(map[*argument]unit))
	}
}

// updateCalleeParams updates the calleeDecl syntax to remove
// substituted parameters and move the receiver (if any) to the head
// of the ordinary parameters.
func updateCalleeParams(calleeDecl *ast.FuncDecl, params []*parameter) {
	// The logic is fiddly because of the three forms of ast.Field:
	//
	//	func(int), func(x int), func(x, y int)
	//
	// Also, ensure that all remaining parameters are named
	// to avoid a mix of named/unnamed when joining (recv, params...).
	// func (T) f(int, bool) -> (_ T, _ int, _ bool)
	// (Strictly, we need do this only for methods and only when
	// the namednesses of Recv and Params differ; that might be tidier.)

	paramIdx := 0 // index in original parameter list (incl. receiver)
	var newParams []*ast.Field
	filterParams := func(field *ast.Field) {
		var names []*ast.Ident
		if field.Names == nil {
			// Unnamed parameter field (e.g. func f(int)
			if params[paramIdx] != nil {
				// Give it an explicit name "_" since we will
				// make the receiver (if any) a regular parameter
				// and one cannot mix named and unnamed parameters.
				names = append(names, makeIdent("_"))
			}
			paramIdx++
		} else {
			// Named parameter field e.g. func f(x, y int)
			// Remove substituted parameters in place.
			// If all were substituted, delete field.
			for _, id := range field.Names {
				if pinfo := params[paramIdx]; pinfo != nil {
					// Rename unreferenced parameters with "_".
					// This is crucial for binding decls, since
					// unlike parameters, they are subject to
					// "unreferenced var" checks.
					if len(pinfo.info.Refs) == 0 {
						id = makeIdent("_")
					}
					names = append(names, id)
				}
				paramIdx++
			}
		}
		if names != nil {
			newParams = append(newParams, &ast.Field{
				Names: names,
				Type:  field.Type,
			})
		}
	}
	if calleeDecl.Recv != nil {
		filterParams(calleeDecl.Recv.List[0])
		calleeDecl.Recv = nil
	}
	for _, field := range calleeDecl.Type.Params.List {
		filterParams(field)
	}
	calleeDecl.Type.Params.List = newParams
}

// bindingDeclInfo records information about the binding decl produced by
// createBindingDecl.
type bindingDeclInfo struct {
	names map[string]bool // names bound by the binding decl; possibly empty
	stmt  ast.Stmt        // the binding decl itself
}

// createBindingDecl constructs a "binding decl" that implements
// parameter assignment and declares any named result variables
// referenced by the callee. It returns nil if there were no
// unsubstituted parameters.
//
// It may not always be possible to create the decl (e.g. due to
// shadowing), in which case it also returns nil; but if it succeeds,
// the declaration may be used by reduction strategies to relax the
// requirement that all parameters have been substituted.
//
// For example, a call:
//
//	f(a0, a1, a2)
//
// where:
//
//	func f(p0, p1 T0, p2 T1) { body }
//
// reduces to:
//
//	{
//	  var (
//	    p0, p1 T0 = a0, a1
//	    p2     T1 = a2
//	  )
//	  body
//	}
//
// so long as p0, p1 ∉ freevars(T1) or freevars(a2), and so on,
// because each spec is statically resolved in sequence and
// dynamically assigned in sequence. By contrast, all
// parameters are resolved simultaneously and assigned
// simultaneously.
//
// The pX names should already be blank ("_") if the parameter
// is unreferenced; this avoids "unreferenced local var" checks.
//
// Strategies may impose additional checks on return
// conversions, labels, defer, etc.
func createBindingDecl(logf logger, caller *Caller, args []*argument, calleeDecl *ast.FuncDecl, results []*paramInfo) *bindingDeclInfo {
	// Spread calls are tricky as they may not align with the
	// parameters' field groupings nor types.
	// For example, given
	//   func g() (int, string)
	// the call
	//   f(g())
	// is legal with these decls of f:
	//   func f(int, string)
	//   func f(x, y any)
	//   func f(x, y ...any)
	// TODO(adonovan): support binding decls for spread calls by
	// splitting parameter groupings as needed.
	if lastArg := last(args); lastArg != nil && lastArg.spread {
		logf("binding decls not yet supported for spread calls")
		return nil
	}

	var (
		specs []ast.Spec
		names = make(map[string]bool) // names defined by previous specs
	)
	// shadow reports whether any name referenced by spec is
	// shadowed by a name declared by a previous spec (since,
	// unlike parameters, each spec of a var decl is within the
	// scope of the previous specs).
	shadow := func(spec *ast.ValueSpec) bool {
		// Compute union of free names of type and values
		// and detect shadowing. Values is the arguments
		// (caller syntax), so we can use type info.
		// But Type is the untyped callee syntax,
		// so we have to use a syntax-only algorithm.
		const includeComplitIdents = true
		free := free.Names(spec.Type, includeComplitIdents)
		for _, value := range spec.Values {
			for name := range freeVars(caller.Info, value) {
				free[name] = true
			}
		}
		for name := range free {
			if names[name] {
				logf("binding decl would shadow free name %q", name)
				return true
			}
		}
		for _, id := range spec.Names {
			if id.Name != "_" {
				names[id.Name] = true
			}
		}
		return false
	}

	// parameters
	//
	// Bind parameters that were not eliminated through
	// substitution. (Non-nil arguments correspond to the
	// remaining parameters in calleeDecl.)
	var values []ast.Expr
	for _, arg := range args {
		if arg != nil {
			values = append(values, arg.expr)
		}
	}
	for _, field := range calleeDecl.Type.Params.List {
		// Each field (param group) becomes a ValueSpec.
		spec := &ast.ValueSpec{
			Names:  cleanNodes(field.Names),
			Type:   cleanNode(field.Type),
			Values: values[:len(field.Names)],
		}
		values = values[len(field.Names):]
		if shadow(spec) {
			return nil
		}
		specs = append(specs, spec)
	}
	assert(len(values) == 0, "args/params mismatch")

	// results
	//
	// Add specs to declare any named result
	// variables that are referenced by the body.
	if calleeDecl.Type.Results != nil {
		resultIdx := 0
		for _, field := range calleeDecl.Type.Results.List {
			if field.Names == nil {
				resultIdx++
				continue // unnamed field
			}
			var names []*ast.Ident
			for _, id := range field.Names {
				if len(results[resultIdx].Refs) > 0 {
					names = append(names, id)
				}
				resultIdx++
			}
			if len(names) > 0 {
				spec := &ast.ValueSpec{
					Names: cleanNodes(names),
					Type:  cleanNode(field.Type),
				}
				if shadow(spec) {
					return nil
				}
				specs = append(specs, spec)
			}
		}
	}

	if len(specs) == 0 {
		logf("binding decl not needed: all parameters substituted")
		return nil
	}

	stmt := &ast.DeclStmt{
		Decl: &ast.GenDecl{
			Tok:   token.VAR,
			Specs: specs,
		},
	}
	logf("binding decl: %s", debugFormatNode(caller.Fset, stmt))
	return &bindingDeclInfo{names: names, stmt: stmt}
}

// lookup does a symbol lookup in the lexical environment of the caller.
func (caller *Caller) lookup(name string) types.Object {
	pos := caller.Call.Pos()
	for _, n := range caller.path {
		if scope := scopeFor(caller.Info, n); scope != nil {
			if _, obj := scope.LookupParent(name, pos); obj != nil {
				return obj
			}
		}
	}
	return nil
}

func scopeFor(info *types.Info, n ast.Node) *types.Scope {
	// The function body scope (containing not just params)
	// is associated with the function's type, not body.
	switch fn := n.(type) {
	case *ast.FuncDecl:
		n = fn.Type
	case *ast.FuncLit:
		n = fn.Type
	}
	return info.Scopes[n]
}

// -- predicates over expressions --

// freeVars returns the names of all free identifiers of e:
// those lexically referenced by it but not defined within it.
// (Fields and methods are not included.)
func freeVars(info *types.Info, e ast.Expr) map[string]bool {
	free := make(map[string]bool)
	ast.Inspect(e, func(n ast.Node) bool {
		if id, ok := n.(*ast.Ident); ok {
			// The isField check is so that we don't treat T{f: 0} as a ref to f.
			if obj, ok := info.Uses[id]; ok && !within(obj.Pos(), e) && !isField(obj) {
				free[obj.Name()] = true
			}
		}
		return true
	})
	return free
}

// effects reports whether an expression might change the state of the
// program (through function calls and channel receives) and affect
// the evaluation of subsequent expressions.
func (st *state) effects(info *types.Info, expr ast.Expr) bool {
	effects := false
	ast.Inspect(expr, func(n ast.Node) bool {
		switch n := n.(type) {
		case *ast.FuncLit:
			return false // prune descent

		case *ast.CallExpr:
			if info.Types[n.Fun].IsType() {
				// A conversion T(x) has only the effect of its operand.
			} else if !typesinternal.CallsPureBuiltin(info, n) {
				// A handful of built-ins have no effect
				// beyond those of their arguments.
				// All other calls (including append, copy, recover)
				// have unknown effects.
				//
				// As with 'pure', there is room for
				// improvement by inspecting the callee.
				effects = true
			}

		case *ast.UnaryExpr:
			if n.Op == token.ARROW { // <-ch
				effects = true
			}
		}
		return true
	})

	// Even if consideration of effects is not desired,
	// we continue to compute, log, and discard them.
	if st.opts.IgnoreEffects && effects {
		effects = false
		st.opts.Logf("ignoring potential effects of argument %s",
			debugFormatNode(st.caller.Fset, expr))
	}

	return effects
}

// pure reports whether an expression has the same result no matter
// when it is executed relative to other expressions, so it can be
// commuted with any other expression or statement without changing
// its meaning.
//
// An expression is considered impure if it reads the contents of any
// variable, with the exception of "single assignment" local variables
// (as classified by the provided callback), which are never updated
// after their initialization.
//
// Pure does not imply duplicable: for example, new(T) and T{} are
// pure expressions but both return a different value each time they
// are evaluated, so they are not safe to duplicate.
//
// Purity does not imply freedom from run-time panics. We assume that
// target programs do not encounter run-time panics nor depend on them
// for correct operation.
//
// TODO(adonovan): add unit tests of this function.
func pure(info *types.Info, assign1 func(*types.Var) bool, e ast.Expr) bool {
	var pure func(e ast.Expr) bool
	pure = func(e ast.Expr) bool {
		switch e := e.(type) {
		case *ast.ParenExpr:
			return pure(e.X)

		case *ast.Ident:
			if v, ok := info.Uses[e].(*types.Var); ok {
				// In general variables are impure
				// as they may be updated, but
				// single-assignment local variables
				// never change value.
				//
				// We assume all package-level variables
				// may be updated, but for non-exported
				// ones we could do better by analyzing
				// the complete package.
				return !isPkgLevel(v) && assign1(v)
			}

			// All other kinds of reference are pure.
			return true

		case *ast.FuncLit:
			// A function literal may allocate a closure that
			// references mutable variables, but mutation
			// cannot be observed without calling the function,
			// and calls are considered impure.
			return true

		case *ast.BasicLit:
			return true

		case *ast.UnaryExpr: // + - ! ^ & but not <-
			return e.Op != token.ARROW && pure(e.X)

		case *ast.BinaryExpr: // arithmetic, shifts, comparisons, &&/||
			return pure(e.X) && pure(e.Y)

		case *ast.CallExpr:
			// A conversion is as pure as its operand.
			if info.Types[e.Fun].IsType() {
				return pure(e.Args[0])
			}

			// Calls to some built-ins are as pure as their arguments.
			if typesinternal.CallsPureBuiltin(info, e) {
				for _, arg := range e.Args {
					if !pure(arg) {
						return false
					}
				}
				return true
			}

			// All other calls are impure, so we can
			// reject them without even looking at e.Fun.
			//
			// More sophisticated analysis could infer purity in
			// commonly used functions such as strings.Contains;
			// perhaps we could offer the client a hook so that
			// go/analysis-based implementation could exploit the
			// results of a purity analysis. But that would make
			// the inliner's choices harder to explain.
			return false

		case *ast.CompositeLit:
			// T{...} is as pure as its elements.
			for _, elt := range e.Elts {
				if kv, ok := elt.(*ast.KeyValueExpr); ok {
					if !pure(kv.Value) {
						return false
					}
					if id, ok := kv.Key.(*ast.Ident); ok {
						if v, ok := info.Uses[id].(*types.Var); ok && v.IsField() {
							continue // struct {field: value}
						}
					}
					// map/slice/array {key: value}
					if !pure(kv.Key) {
						return false
					}

				} else if !pure(elt) {
					return false
				}
			}
			return true

		case *ast.SelectorExpr:
			if seln, ok := info.Selections[e]; ok {
				// See types.SelectionKind for background.
				switch seln.Kind() {
				case types.MethodExpr:
					// A method expression T.f acts like a
					// reference to a func decl, so it is pure.
					return true

				case types.MethodVal, types.FieldVal:
					// A field or method selection x.f is pure
					// if x is pure and the selection does
					// not indirect a pointer.
					return !indirectSelection(seln) && pure(e.X)

				default:
					panic(seln)
				}
			} else {
				// A qualified identifier is
				// treated like an unqualified one.
				return pure(e.Sel)
			}

		case *ast.StarExpr:
			return false // *ptr depends on the state of the heap

		default:
			return false
		}
	}
	return pure(e)
}

// duplicable reports whether it is appropriate for the expression to
// be freely duplicated.
//
// Given the declaration
//
//	func f(x T) T { return x + g() + x }
//
// an argument y is considered duplicable if we would wish to see a
// call f(y) simplified to y+g()+y. This is true for identifiers,
// integer literals, unary negation, and selectors x.f where x is not
// a pointer. But we would not wish to duplicate expressions that:
// - have side effects (e.g. nearly all calls),
// - are not referentially transparent (e.g. &T{}, ptr.field, *ptr), or
// - are long (e.g. "huge string literal").
func duplicable(info *types.Info, e ast.Expr) bool {
	switch e := e.(type) {
	case *ast.ParenExpr:
		return duplicable(info, e.X)

	case *ast.Ident:
		return true

	case *ast.BasicLit:
		v := info.Types[e].Value
		switch e.Kind {
		case token.INT:
			return true // any int
		case token.STRING:
			return consteq(v, kZeroString) // only ""
		case token.FLOAT:
			return consteq(v, kZeroFloat) || consteq(v, kOneFloat) // only 0.0 or 1.0
		}

	case *ast.UnaryExpr: // e.g. +1, -1
		return (e.Op == token.ADD || e.Op == token.SUB) && duplicable(info, e.X)

	case *ast.CompositeLit:
		// Empty struct or array literals T{} are duplicable.
		// (Non-empty literals are too verbose, and slice/map
		// literals allocate indirect variables.)
		if len(e.Elts) == 0 {
			switch info.TypeOf(e).Underlying().(type) {
			case *types.Struct, *types.Array:
				return true
			}
		}
		return false

	case *ast.CallExpr:
		// Treat type conversions as duplicable if they do not observably allocate.
		// The only cases of observable allocations are
		// the `[]byte(string)` and `[]rune(string)` conversions.
		//
		// Duplicating string([]byte) conversions increases
		// allocation but doesn't change behavior, but the
		// reverse, []byte(string), allocates a distinct array,
		// which is observable.

		if !info.Types[e.Fun].IsType() { // check whether e.Fun is a type conversion
			return false
		}

		fun := info.TypeOf(e.Fun)
		arg := info.TypeOf(e.Args[0])

		switch fun := fun.Underlying().(type) {
		case *types.Slice:
			// Do not mark []byte(string) and []rune(string) as duplicable.
			elem, ok := fun.Elem().Underlying().(*types.Basic)
			if ok && (elem.Kind() == types.Rune || elem.Kind() == types.Byte) {
				from, ok := arg.Underlying().(*types.Basic)
				isString := ok && from.Info()&types.IsString != 0
				return !isString
			}
		case *types.TypeParam:
			return false // be conservative
		}
		return true

	case *ast.SelectorExpr:
		if seln, ok := info.Selections[e]; ok {
			// A field or method selection x.f is referentially
			// transparent if it does not indirect a pointer.
			return !indirectSelection(seln)
		}
		// A qualified identifier pkg.Name is referentially transparent.
		return true
	}
	return false
}

func consteq(x, y constant.Value) bool {
	return constant.Compare(x, token.EQL, y)
}

var (
	kZeroInt    = constant.MakeInt64(0)
	kZeroString = constant.MakeString("")
	kZeroFloat  = constant.MakeFloat64(0.0)
	kOneFloat   = constant.MakeFloat64(1.0)
)

// -- inline helpers --

func assert(cond bool, msg string) {
	if !cond {
		panic(msg)
	}
}

// blanks returns a slice of n > 0 blank identifiers.
func blanks[E ast.Expr](n int) []E {
	if n == 0 {
		panic("blanks(0)")
	}
	res := make([]E, n)
	for i := range res {
		res[i] = ast.Expr(makeIdent("_")).(E) // ugh
	}
	return res
}

func makeIdent(name string) *ast.Ident {
	return &ast.Ident{Name: name}
}

// importedPkgName returns the PkgName object declared by an ImportSpec.
// TODO(adonovan): make this a method of types.Info (#62037).
func importedPkgName(info *types.Info, imp *ast.ImportSpec) (*types.PkgName, bool) {
	var obj types.Object
	if imp.Name != nil {
		obj = info.Defs[imp.Name]
	} else {
		obj = info.Implicits[imp]
	}
	pkgname, ok := obj.(*types.PkgName)
	return pkgname, ok
}

func isPkgLevel(obj types.Object) bool {
	// TODO(adonovan): consider using the simpler obj.Parent() ==
	// obj.Pkg().Scope() instead. But be sure to test carefully
	// with instantiations of generics.
	return obj.Pkg().Scope().Lookup(obj.Name()) == obj
}

// callContext returns the two nodes immediately enclosing the call
// (specified as a PathEnclosingInterval), ignoring parens.
func callContext(callPath []ast.Node) (parent, grandparent ast.Node) {
	_ = callPath[0].(*ast.CallExpr) // sanity check
	for _, n := range callPath[1:] {
		if !is[*ast.ParenExpr](n) {
			if parent == nil {
				parent = n
			} else {
				return parent, n
			}
		}
	}
	return parent, nil
}

// hasLabelConflict reports whether the set of labels of the function
// enclosing the call (specified as a PathEnclosingInterval)
// intersects with the set of callee labels.
func hasLabelConflict(callPath []ast.Node, calleeLabels []string) bool {
	labels := callerLabels(callPath)
	for _, label := range calleeLabels {
		if labels[label] {
			return true // conflict
		}
	}
	return false
}

// callerLabels returns the set of control labels in the function (if
// any) enclosing the call (specified as a PathEnclosingInterval).
func callerLabels(callPath []ast.Node) map[string]bool {
	var callerBody *ast.BlockStmt
	switch f := callerFunc(callPath).(type) {
	case *ast.FuncDecl:
		callerBody = f.Body
	case *ast.FuncLit:
		callerBody = f.Body
	}
	var labels map[string]bool
	if callerBody != nil {
		ast.Inspect(callerBody, func(n ast.Node) bool {
			switch n := n.(type) {
			case *ast.FuncLit:
				return false // prune traversal
			case *ast.LabeledStmt:
				if labels == nil {
					labels = make(map[string]bool)
				}
				labels[n.Label.Name] = true
			}
			return true
		})
	}
	return labels
}

// callerFunc returns the innermost Func{Decl,Lit} node enclosing the
// call (specified as a PathEnclosingInterval).
func callerFunc(callPath []ast.Node) ast.Node {
	_ = callPath[0].(*ast.CallExpr) // sanity check
	for _, n := range callPath[1:] {
		if is[*ast.FuncDecl](n) || is[*ast.FuncLit](n) {
			return n
		}
	}
	return nil
}

// callStmt reports whether the function call (specified
// as a PathEnclosingInterval) appears within an ExprStmt,
// and returns it if so.
//
// If unrestricted, callStmt returns nil if the ExprStmt f() appears
// in a restricted context (such as "if f(); cond {") where it cannot
// be replaced by an arbitrary statement. (See "statement theory".)
func callStmt(callPath []ast.Node, unrestricted bool) *ast.ExprStmt {
	parent, _ := callContext(callPath)
	stmt, ok := parent.(*ast.ExprStmt)
	if ok && unrestricted {
		switch callPath[slices.Index(callPath, ast.Node(stmt))+1].(type) {
		case *ast.LabeledStmt,
			*ast.BlockStmt,
			*ast.CaseClause,
			*ast.CommClause:
			// unrestricted
		default:
			// TODO(adonovan): handle restricted
			// XYZStmt.Init contexts (but not ForStmt.Post)
			// by creating a block around the if/for/switch:
			// "if f(); cond {"  ->  "{ stmts; if cond {"

			return nil // restricted
		}
	}
	return stmt
}

// Statement theory
//
// These are all the places a statement may appear in the AST:
//
// LabeledStmt.Stmt       Stmt      -- any
// BlockStmt.List       []Stmt      -- any (but see switch/select)
// IfStmt.Init            Stmt?     -- simple
// IfStmt.Body            BlockStmt
// IfStmt.Else            Stmt?     -- IfStmt or BlockStmt
// CaseClause.Body      []Stmt      -- any
// SwitchStmt.Init        Stmt?     -- simple
// SwitchStmt.Body        BlockStmt -- CaseClauses only
// TypeSwitchStmt.Init    Stmt?     -- simple
// TypeSwitchStmt.Assign  Stmt      -- AssignStmt(TypeAssertExpr) or ExprStmt(TypeAssertExpr)
// TypeSwitchStmt.Body    BlockStmt -- CaseClauses only
// CommClause.Comm        Stmt?     -- SendStmt or ExprStmt(UnaryExpr) or AssignStmt(UnaryExpr)
// CommClause.Body      []Stmt      -- any
// SelectStmt.Body        BlockStmt -- CommClauses only
// ForStmt.Init           Stmt?     -- simple
// ForStmt.Post           Stmt?     -- simple
// ForStmt.Body           BlockStmt
// RangeStmt.Body         BlockStmt
//
// simple = AssignStmt | SendStmt | IncDecStmt | ExprStmt.
//
// A BlockStmt cannot replace an ExprStmt in
// {If,Switch,TypeSwitch}Stmt.Init or ForStmt.Post.
// That is allowed only within:
//   LabeledStmt.Stmt       Stmt
//   BlockStmt.List       []Stmt
//   CaseClause.Body      []Stmt
//   CommClause.Body      []Stmt

// replaceNode performs a destructive update of the tree rooted at
// root, replacing each occurrence of "from" with "to". If to is nil and
// the element is within a slice, the slice element is removed.
//
// The root itself cannot be replaced; an attempt will panic.
//
// This function must not be called on the caller's syntax tree.
//
// TODO(adonovan): polish this up and move it to astutil package.
// TODO(adonovan): needs a unit test.
func replaceNode(root ast.Node, from, to ast.Node) {
	if from == nil {
		panic("from == nil")
	}
	if reflect.ValueOf(from).IsNil() {
		panic(fmt.Sprintf("from == (%T)(nil)", from))
	}
	if from == root {
		panic("from == root")
	}
	found := false
	var parent reflect.Value // parent variable of interface type, containing a pointer
	var visit func(reflect.Value)
	visit = func(v reflect.Value) {
		switch v.Kind() {
		case reflect.Pointer:
			if v.Interface() == from {
				found = true

				// If v is a struct field or array element
				// (e.g. Field.Comment or Field.Names[i])
				// then it is addressable (a pointer variable).
				//
				// But if it was the value an interface
				// (e.g. *ast.Ident within ast.Node)
				// then it is non-addressable, and we need
				// to set the enclosing interface (parent).
				if !v.CanAddr() {
					v = parent
				}

				// to=nil => use zero value
				var toV reflect.Value
				if to != nil {
					toV = reflect.ValueOf(to)
				} else {
					toV = reflect.Zero(v.Type()) // e.g. ast.Expr(nil)
				}
				v.Set(toV)

			} else if !v.IsNil() {
				switch v.Interface().(type) {
				case *ast.Object, *ast.Scope:
					// Skip fields of types potentially involved in cycles.
				default:
					visit(v.Elem())
				}
			}

		case reflect.Struct:
			for i := range v.Type().NumField() {
				visit(v.Field(i))
			}

		case reflect.Slice:
			compact := false
			for i := range v.Len() {
				visit(v.Index(i))
				if v.Index(i).IsNil() {
					compact = true
				}
			}
			if compact {
				// Elements were deleted. Eliminate nils.
				// (Do this is a second pass to avoid
				// unnecessary writes in the common case.)
				j := 0
				for i := range v.Len() {
					if !v.Index(i).IsNil() {
						v.Index(j).Set(v.Index(i))
						j++
					}
				}
				v.SetLen(j)
			}
		case reflect.Interface:
			parent = v
			visit(v.Elem())

		case reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.UnsafePointer:
			panic(v) // unreachable in AST
		default:
			// bool, string, number: nop
		}
		parent = reflect.Value{}
	}
	visit(reflect.ValueOf(root))
	if !found {
		panic(fmt.Sprintf("%T not found", from))
	}
}

// cleanNode returns a clone of node with positions cleared.
//
// It should be used for any callee nodes that are formatted using the caller
// file set.
func cleanNode[T ast.Node](node T) T {
	clone := internalastutil.CloneNode(node)
	clearPositions(clone)
	return clone
}

func cleanNodes[T ast.Node](nodes []T) []T {
	var clean []T
	for _, node := range nodes {
		clean = append(clean, cleanNode(node))
	}
	return clean
}

// clearPositions destroys token.Pos information within the tree rooted at root,
// as positions in callee trees may cause caller comments to be emitted prematurely.
//
// In general it isn't safe to clear a valid Pos because some of them
// (e.g. CallExpr.Ellipsis, TypeSpec.Assign) are significant to
// go/printer, so this function sets each non-zero Pos to 1, which
// suffices to avoid advancing the printer's comment cursor.
//
// This function mutates its argument; do not invoke on caller syntax.
//
// TODO(adonovan): remove this horrendous workaround when #20744 is finally fixed.
func clearPositions(root ast.Node) {
	posType := reflect.TypeFor[token.Pos]()
	ast.Inspect(root, func(n ast.Node) bool {
		if n != nil {
			v := reflect.ValueOf(n).Elem() // deref the pointer to struct
			fields := v.Type().NumField()
			for i := range fields {
				f := v.Field(i)
				// Clearing Pos arbitrarily is destructive,
				// as its presence may be semantically significant
				// (e.g. CallExpr.Ellipsis, TypeSpec.Assign)
				// or affect formatting preferences (e.g. GenDecl.Lparen).
				//
				// Note: for proper formatting, it may be necessary to be selective
				// about which positions we set to 1 vs which we set to token.NoPos.
				// (e.g. we can set most to token.NoPos, save the few that are
				// significant).
				if f.Type() == posType {
					if f.Interface() != token.NoPos {
						f.Set(reflect.ValueOf(token.Pos(1)))
					}
				}
			}
		}
		return true
	})
}

// findIdent finds the Ident beneath root that has the given pos.
// It returns the path to the ident (excluding the ident), and the ident
// itself, where the path is the sequence of ast.Nodes encountered in a
// depth-first search to find ident.
func findIdent(root ast.Node, pos token.Pos) ([]ast.Node, *ast.Ident) {
	// TODO(adonovan): opt: skip subtrees that don't contain pos.
	var (
		path  []ast.Node
		found *ast.Ident
	)
	ast.Inspect(root, func(n ast.Node) bool {
		if found != nil {
			return false
		}
		if n == nil {
			path = path[:len(path)-1]
			return false
		}
		if id, ok := n.(*ast.Ident); ok {
			if id.Pos() == pos {
				found = id
				return true
			}
		}
		path = append(path, n)
		return true
	})
	if found == nil {
		panic(fmt.Sprintf("findIdent %d not found in %s",
			pos, debugFormatNode(token.NewFileSet(), root)))
	}
	return path, found
}

func prepend[T any](elem T, slice ...T) []T {
	return append([]T{elem}, slice...)
}

// debugFormatNode formats a node or returns a formatting error.
// Its sloppy treatment of errors is appropriate only for logging.
func debugFormatNode(fset *token.FileSet, n ast.Node) string {
	var out strings.Builder
	if err := format.Node(&out, fset, n); err != nil {
		out.WriteString(err.Error())
	}
	return out.String()
}

func shallowCopy[T any](ptr *T) *T {
	copy := *ptr
	return &copy
}

// ∀
func forall[T any](list []T, f func(i int, x T) bool) bool {
	for i, x := range list {
		if !f(i, x) {
			return false
		}
	}
	return true
}

// ∃
func exists[T any](list []T, f func(i int, x T) bool) bool {
	for i, x := range list {
		if f(i, x) {
			return true
		}
	}
	return false
}

// last returns the last element of a slice, or zero if empty.
func last[T any](slice []T) T {
	n := len(slice)
	if n > 0 {
		return slice[n-1]
	}
	return *new(T)
}

// declares returns the set of lexical names declared by a
// sequence of statements from the same block, excluding sub-blocks.
// (Lexical names do not include control labels.)
func declares(stmts []ast.Stmt) map[string]bool {
	names := make(map[string]bool)
	for _, stmt := range stmts {
		switch stmt := stmt.(type) {
		case *ast.DeclStmt:
			for _, spec := range stmt.Decl.(*ast.GenDecl).Specs {
				switch spec := spec.(type) {
				case *ast.ValueSpec:
					for _, id := range spec.Names {
						names[id.Name] = true
					}
				case *ast.TypeSpec:
					names[spec.Name.Name] = true
				}
			}

		case *ast.AssignStmt:
			if stmt.Tok == token.DEFINE {
				for _, lhs := range stmt.Lhs {
					names[lhs.(*ast.Ident).Name] = true
				}
			}
		}
	}
	delete(names, "_")
	return names
}

// A importNameFunc is used to query local import names in the caller, in a
// particular shadowing context.
//
// The shadow map contains additional names shadowed in the inlined code, at
// the position the local import name is to be used. The shadow map only needs
// to contain newly introduced names in the inlined code; names shadowed at the
// caller are handled automatically.
type importNameFunc = func(pkgPath string, shadow shadowMap) string

// assignStmts rewrites a statement assigning the results of a call into zero
// or more statements that assign its return operands, or (nil, false) if no
// such rewrite is possible. The set of bindings created by the result of
// assignStmts is the same as the set of bindings created by the callerStmt.
//
// The callee must contain exactly one return statement.
//
// This is (once again) a surprisingly complex task. For example, depending on
// types and existing bindings, the assignment
//
//	a, b := f()
//
// could be rewritten as:
//
//	a, b := 1, 2
//
// but may need to be written as:
//
//	a, b := int8(1), int32(2)
//
// In the case where the return statement within f is a spread call to another
// function g(), we cannot explicitly convert the return values inline, and so
// it may be necessary to split the declaration and assignment of variables
// into separate statements:
//
//	a, b := g()
//
// or
//
//	var a int32
//	a, b = g()
//
// or
//
//	var (
//		a int8
//		b int32
//	)
//	a, b = g()
//
// Note: assignStmts may return (nil, true) if it determines that the rewritten
// assignment consists only of _ = nil assignments.
func (st *state) assignStmts(callerStmt *ast.AssignStmt, returnOperands []ast.Expr, importName importNameFunc) ([]ast.Stmt, bool) {
	logf, caller, callee := st.opts.Logf, st.caller, &st.callee.impl

	assert(len(callee.Returns) == 1, "unexpected multiple returns")
	resultInfo := callee.Returns[0]

	// When constructing assign statements, we need to make sure that we don't
	// modify types on the left-hand side, such as would happen if the type of a
	// RHS expression does not match the corresponding LHS type at the caller
	// (due to untyped conversion or interface widening).
	//
	// This turns out to be remarkably tricky to handle correctly.
	//
	// Substrategies below are labeled as `Substrategy <name>:`.

	// Collect LHS information.
	var (
		lhs    []ast.Expr                                // shallow copy of the LHS slice, for mutation
		defs   = make([]*ast.Ident, len(callerStmt.Lhs)) // indexes in lhs of defining identifiers
		blanks = make([]bool, len(callerStmt.Lhs))       // indexes in lhs of blank identifiers
		byType typeutil.Map                              // map of distinct types -> indexes, for writing specs later
	)
	for i, expr := range callerStmt.Lhs {
		lhs = append(lhs, expr)
		if name, ok := expr.(*ast.Ident); ok {
			if name.Name == "_" {
				blanks[i] = true
				continue // no type
			}

			if obj, isDef := caller.Info.Defs[name]; isDef {
				defs[i] = name
				typ := obj.Type()
				idxs, _ := byType.At(typ).([]int)
				idxs = append(idxs, i)
				byType.Set(typ, idxs)
			}
		}
	}

	// Collect RHS information
	//
	// The RHS is either a parallel assignment or spread assignment, but by
	// looping over both callerStmt.Rhs and returnOperands we handle both.
	var (
		rhs             []ast.Expr              // new RHS of assignment, owned by the inliner
		callIdx         = -1                    // index of the call among the original RHS
		nilBlankAssigns = make(map[int]unit)    // indexes in rhs of _ = nil assignments, which can be deleted
		freeNames       = make(map[string]bool) // free(ish) names among rhs expressions
		nonTrivial      = make(map[int]bool)    // indexes in rhs of nontrivial result conversions
	)
	const includeComplitIdents = true

	for i, expr := range callerStmt.Rhs {
		if expr == caller.Call {
			assert(callIdx == -1, "malformed (duplicative) AST")
			callIdx = i
			for j, returnOperand := range returnOperands {
				maps.Copy(freeNames, free.Names(returnOperand, includeComplitIdents))
				rhs = append(rhs, returnOperand)
				if resultInfo[j]&nonTrivialResult != 0 {
					nonTrivial[i+j] = true
				}
				if blanks[i+j] && resultInfo[j]&untypedNilResult != 0 {
					nilBlankAssigns[i+j] = unit{}
				}
			}
		} else {
			// We must clone before clearing positions, since e came from the caller.
			expr = internalastutil.CloneNode(expr)
			clearPositions(expr)
			maps.Copy(freeNames, free.Names(expr, includeComplitIdents))
			rhs = append(rhs, expr)
		}
	}
	assert(callIdx >= 0, "failed to find call in RHS")

	// Substrategy "splice": Check to see if we can simply splice in the result
	// expressions from the callee, such as simplifying
	//
	//  x, y := f()
	//
	// to
	//
	//  x, y := e1, e2
	//
	// where the types of x and y match the types of e1 and e2.
	//
	// This works as long as we don't need to write any additional type
	// information.
	if len(nonTrivial) == 0 { // no non-trivial conversions to worry about

		logf("substrategy: splice assignment")
		return []ast.Stmt{&ast.AssignStmt{
			Lhs:    lhs,
			Tok:    callerStmt.Tok,
			TokPos: callerStmt.TokPos,
			Rhs:    rhs,
		}}, true
	}

	// Inlining techniques below will need to write type information in order to
	// preserve the correct types of LHS identifiers.
	//
	// typeExpr is a simple helper to write out type expressions. It currently
	// handles (possibly qualified) type names.
	//
	// TODO(rfindley):
	//   1. expand this to handle more type expressions.
	//   2. refactor to share logic with callee rewriting.
	universeAny := types.Universe.Lookup("any")
	typeExpr := func(typ types.Type, shadow shadowMap) ast.Expr {
		var (
			typeName string
			obj      *types.TypeName // nil for basic types
		)
		if tname := typesinternal.TypeNameFor(typ); tname != nil {
			obj = tname
			typeName = tname.Name()
		}

		// Special case: check for universe "any".
		// TODO(golang/go#66921): this may become unnecessary if any becomes a proper alias.
		if typ == universeAny.Type() {
			typeName = "any"
		}

		if typeName == "" {
			return nil
		}

		if obj == nil || obj.Pkg() == nil || obj.Pkg() == caller.Types { // local type or builtin
			if shadow[typeName] != 0 {
				logf("cannot write shadowed type name %q", typeName)
				return nil
			}
			obj, _ := caller.lookup(typeName).(*types.TypeName)
			if obj != nil && types.Identical(obj.Type(), typ) {
				return ast.NewIdent(typeName)
			}
		} else if pkgName := importName(obj.Pkg().Path(), shadow); pkgName != "" {
			return &ast.SelectorExpr{
				X:   ast.NewIdent(pkgName),
				Sel: ast.NewIdent(typeName),
			}
		}
		return nil
	}

	// Substrategy "spread": in the case of a spread call (func f() (T1, T2) return
	// g()), since we didn't hit the 'splice' substrategy, there must be some
	// non-declaring expression on the LHS. Simplify this by pre-declaring
	// variables, rewriting
	//
	//   x, y := f()
	//
	// to
	//
	//  var x int
	//  x, y = g()
	//
	// Which works as long as the predeclared variables do not overlap with free
	// names on the RHS.
	if len(rhs) != len(lhs) {
		assert(len(rhs) == 1 && len(returnOperands) == 1, "expected spread call")

		for _, id := range defs {
			if id != nil && freeNames[id.Name] {
				// By predeclaring variables, we're changing them to be in scope of the
				// RHS. We can't do this if their names are free on the RHS.
				return nil, false
			}
		}

		// Write out the specs, being careful to avoid shadowing free names in
		// their type expressions.
		var (
			specs    []ast.Spec
			specIdxs []int
			shadow   = make(shadowMap)
		)
		failed := false
		byType.Iterate(func(typ types.Type, v any) {
			if failed {
				return
			}
			idxs := v.([]int)
			specIdxs = append(specIdxs, idxs[0])
			texpr := typeExpr(typ, shadow)
			if texpr == nil {
				failed = true
				return
			}
			spec := &ast.ValueSpec{
				Type: texpr,
			}
			for _, idx := range idxs {
				spec.Names = append(spec.Names, ast.NewIdent(defs[idx].Name))
			}
			specs = append(specs, spec)
		})
		if failed {
			return nil, false
		}
		logf("substrategy: spread assignment")
		return []ast.Stmt{
			&ast.DeclStmt{
				Decl: &ast.GenDecl{
					Tok:   token.VAR,
					Specs: specs,
				},
			},
			&ast.AssignStmt{
				Lhs: callerStmt.Lhs,
				Tok: token.ASSIGN,
				Rhs: returnOperands,
			},
		}, true
	}

	assert(len(lhs) == len(rhs), "mismatching LHS and RHS")

	// Substrategy "convert": write out RHS expressions with explicit type conversions
	// as necessary, rewriting
	//
	//  x, y := f()
	//
	// to
	//
	//  x, y := 1, int32(2)
	//
	// As required to preserve types.
	//
	// In the special case of _ = nil, which is disallowed by the type checker
	// (since nil has no default type), we delete the assignment.
	var origIdxs []int // maps back to original indexes after lhs and rhs are pruned
	i := 0
	for j := range lhs {
		if _, ok := nilBlankAssigns[j]; !ok {
			lhs[i] = lhs[j]
			rhs[i] = rhs[j]
			origIdxs = append(origIdxs, j)
			i++
		}
	}
	lhs = lhs[:i]
	rhs = rhs[:i]

	if len(lhs) == 0 {
		logf("trivial assignment after pruning nil blanks assigns")
		// After pruning, we have no remaining assignments.
		// Signal this by returning a non-nil slice of statements.
		return nil, true
	}

	// Write out explicit conversions as necessary.
	//
	// A conversion is necessary if the LHS is being defined, and the RHS return
	// involved a nontrivial implicit conversion.
	for i, expr := range rhs {
		idx := origIdxs[i]
		if nonTrivial[idx] && defs[idx] != nil {
			typ := caller.Info.TypeOf(lhs[i])
			texpr := typeExpr(typ, nil)
			if texpr == nil {
				return nil, false
			}
			if _, ok := texpr.(*ast.StarExpr); ok {
				// TODO(rfindley): is this necessary? Doesn't the formatter add these parens?
				texpr = &ast.ParenExpr{X: texpr} // *T -> (*T)   so that (*T)(x) is valid
			}
			rhs[i] = &ast.CallExpr{
				Fun:  texpr,
				Args: []ast.Expr{expr},
			}
		}
	}
	logf("substrategy: convert assignment")
	return []ast.Stmt{&ast.AssignStmt{
		Lhs: lhs,
		Tok: callerStmt.Tok,
		Rhs: rhs,
	}}, true
}

// tailCallSafeReturn reports whether the callee's return statements may be safely
// used to return from the function enclosing the caller (which must exist).
func tailCallSafeReturn(caller *Caller, calleeSymbol *types.Func, callee *gobCallee) bool {
	// It is safe if all callee returns involve only trivial conversions.
	if !hasNonTrivialReturn(callee.Returns) {
		return true
	}

	var callerType types.Type
	// Find type of innermost function enclosing call.
	// (Beware: Caller.enclosingFunc is the outermost.)
loop:
	for _, n := range caller.path {
		switch f := n.(type) {
		case *ast.FuncDecl:
			callerType = caller.Info.ObjectOf(f.Name).Type()
			break loop
		case *ast.FuncLit:
			callerType = caller.Info.TypeOf(f)
			break loop
		}
	}

	// Non-trivial return conversions in the callee are permitted
	// if the same non-trivial conversion would occur after inlining,
	// i.e. if the caller and callee results tuples are identical.
	callerResults := callerType.(*types.Signature).Results()
	calleeResults := calleeSymbol.Type().(*types.Signature).Results()
	return types.Identical(callerResults, calleeResults)
}

// hasNonTrivialReturn reports whether any of the returns involve a nontrivial
// implicit conversion of a result expression.
func hasNonTrivialReturn(returnInfo [][]returnOperandFlags) bool {
	for _, resultInfo := range returnInfo {
		for _, r := range resultInfo {
			if r&nonTrivialResult != 0 {
				return true
			}
		}
	}
	return false
}

type unit struct{} // for representing sets as maps


================================================
FILE: internal/refactor/inline/inline_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline_test

import (
	"bytes"
	"crypto/sha256"
	"encoding/binary"
	"encoding/gob"
	"fmt"
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"
	"testing"
	"unsafe"

	"golang.org/x/tools/go/ast/astutil"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/analysis/driverutil"
	"golang.org/x/tools/internal/diff"
	"golang.org/x/tools/internal/expect"
	"golang.org/x/tools/internal/refactor"
	"golang.org/x/tools/internal/refactor/inline"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/txtar"
)

// TestData executes test scenarios specified by files in testdata/*.txtar.
// Each txtar file describes two sets of files, some containing Go source
// and others expected results.
//
// The Go source files and go.mod are parsed and type-checked as a Go module.
// Some of these files contain marker comments (in a form described below) describing
// the inlinings to perform and whether they should succeed or fail. A marker
// indicating success refers to another file in the txtar, not a .go
// file, that should contain the contents of the first file after inlining.
//
// The marker format for success is
//
//	@inline(re"pat", wantfile)
//
// The first call in the marker's line that matches pat is inlined, and the contents
// of the resulting file must match the contents of wantfile.
//
// The marker format for failure is
//
//	@inline(re"pat", re"errpat")
//
// The first argument selects the call for inlining as before, and the second
// is a regular expression that must match the text of resulting error.
func TestData(t *testing.T) {
	testenv.NeedsGoPackages(t)

	files, err := filepath.Glob("testdata/*.txtar")
	if err != nil {
		t.Fatal(err)
	}
	for _, file := range files {
		t.Run(filepath.Base(file), func(t *testing.T) {
			t.Parallel()

			// The few tests that use cgo should be in
			// files whose name includes "cgo".
			if strings.Contains(t.Name(), "cgo") {
				testenv.NeedsTool(t, "cgo")
			}

			// Some tests need specific Go versions.
			// TODO(adonovan): remove when go1.26 is assured.
			if strings.HasSuffix(t.Name(), "newexpr.txtar") {
				testenv.NeedsGo1Point(t, 26)
			}

			// Extract archive to temporary tree.
			ar, err := txtar.ParseFile(file)
			if err != nil {
				t.Fatal(err)
			}
			fs, err := txtar.FS(ar)
			if err != nil {
				t.Fatal(err)
			}
			dir := testfiles.CopyToTmp(t, fs)

			// Load packages.
			cfg := &packages.Config{
				Dir:  dir,
				Mode: packages.LoadAllSyntax,
				Env: append(os.Environ(),
					"GO111MODULES=on",
					"GOPATH=",
					"GOWORK=off",
					"GOPROXY=off"),
			}
			pkgs, err := packages.Load(cfg, "./...")
			if err != nil {
				t.Errorf("Load: %v", err)
			}
			// Report parse/type errors; they may be benign.
			packages.Visit(pkgs, nil, func(pkg *packages.Package) {
				for _, err := range pkg.Errors {
					t.Logf("warning: %v", err)
				}
			})

			// Process @inline notes in comments in initial packages.
			for _, pkg := range pkgs {
				for _, file := range pkg.Syntax {
					tokFile := pkg.Fset.File(file.FileStart)
					// Read file content (for @inline regexp, and inliner).
					content, err := os.ReadFile(tokFile.Name())
					if err != nil {
						t.Error(err)
						continue
					}

					// Read and process @inline notes.
					notes, err := expect.ExtractGo(tokFile, file)
					if err != nil {
						t.Errorf("parsing notes in %q: %v", tokFile.Name(), err)
						continue
					}
					for _, note := range notes {
						posn := tokFile.PositionFor(note.Pos, false)
						if note.Name != "inline" {
							t.Errorf("%s: invalid marker @%s", posn, note.Name)
							continue
						}
						if nargs := len(note.Args); nargs != 2 {
							t.Errorf("@inline: want 2 args, got %d", nargs)
							continue
						}
						pattern, ok := note.Args[0].(*regexp.Regexp)
						if !ok {
							t.Errorf("%s: @inline(rx, want): want regular expression rx", posn)
							continue
						}

						// want is a []byte (success) or *Regexp (failure)
						var want any
						switch x := note.Args[1].(type) {
						case string, expect.Identifier:
							name := fmt.Sprint(x)
							for _, file := range ar.Files {
								if file.Name == name {
									want = file.Data
									break
								}
							}
							if want == nil {
								t.Errorf("%s: @inline(rx, want): archive entry %q not found", posn, x)
								continue
							}
						case *regexp.Regexp:
							want = x
						default:
							t.Errorf("%s: @inline(rx, want): want file name (to assert success) or error message regexp (to assert failure)", posn)
							continue
						}
						if err := doInlineNote(t.Logf, pkg, file, content, pattern, posn, want); err != nil {
							t.Errorf("%s: @inline(%v, %v): %v", posn, note.Args[0], note.Args[1], err)
							continue
						}
					}
				}
			}
		})
	}
}

// doInlineNote executes an assertion specified by a single
// @inline(re"pattern", want) note in a comment. It finds the first
// match of regular expression 'pattern' on the same line, finds the
// innermost enclosing CallExpr, and inlines it.
//
// Finally it checks that, on success, the transformed file is equal
// to want (a []byte), or on failure that the error message matches
// want (a *Regexp).
func doInlineNote(logf func(string, ...any), pkg *packages.Package, file *ast.File, content []byte, pattern *regexp.Regexp, posn token.Position, want any) error {
	// Find extent of pattern match within commented line.
	var startPos, endPos token.Pos
	{
		tokFile := pkg.Fset.File(file.FileStart)
		lineStartOffset := int(tokFile.LineStart(posn.Line)) - tokFile.Base()
		line := content[lineStartOffset:]
		if i := bytes.IndexByte(line, '\n'); i >= 0 {
			line = line[:i]
		}
		matches := pattern.FindSubmatchIndex(line)
		var start, end int // offsets
		switch len(matches) {
		case 2:
			// no subgroups: return the range of the regexp expression
			start, end = matches[0], matches[1]
		case 4:
			// one subgroup: return its range
			start, end = matches[2], matches[3]
		default:
			return fmt.Errorf("invalid location regexp %q: expect either 0 or 1 subgroups, got %d",
				pattern, len(matches)/2-1)
		}
		startPos = tokFile.Pos(lineStartOffset + start)
		endPos = tokFile.Pos(lineStartOffset + end)
	}

	// Find innermost call enclosing the pattern match.
	var caller *inline.Caller
	{
		path, _ := astutil.PathEnclosingInterval(file, startPos, endPos)
		for _, n := range path {
			if call, ok := n.(*ast.CallExpr); ok {
				caller = &inline.Caller{
					Fset:  pkg.Fset,
					Types: pkg.Types,
					Info:  pkg.TypesInfo,
					File:  file,
					Call:  call,
				}
				break
			}
		}
		if caller == nil {
			return fmt.Errorf("no enclosing call")
		}
	}

	// Is it a static function call?
	fn := typeutil.StaticCallee(caller.Info, caller.Call)
	if fn == nil {
		return fmt.Errorf("cannot inline: not a static call")
	}

	// Find callee function.
	var calleePkg *packages.Package
	{
		// Is the call within the package?
		if fn.Pkg() == caller.Types {
			calleePkg = pkg // same as caller
		} else {
			// Different package. Load it now.
			// (The primary load loaded all dependencies,
			// but we choose to load it again, with
			// a distinct token.FileSet and types.Importer,
			// to keep the implementation honest.)
			cfg := &packages.Config{
				// TODO(adonovan): get the original module root more cleanly
				Dir:  filepath.Dir(filepath.Dir(pkg.GoFiles[0])),
				Fset: token.NewFileSet(),
				Mode: packages.LoadSyntax,
			}
			roots, err := packages.Load(cfg, fn.Pkg().Path())
			if err != nil {
				return fmt.Errorf("loading callee package: %v", err)
			}
			if packages.PrintErrors(roots) > 0 {
				return fmt.Errorf("callee package had errors") // (see log)
			}
			calleePkg = roots[0]
		}
	}

	calleeDecl, err := findFuncByPosition(calleePkg, caller.Fset.PositionFor(fn.Pos(), false))
	if err != nil {
		return err
	}

	// Do the inlining. For the purposes of the test,
	// AnalyzeCallee and Inline are a single operation.
	res, err := func() (*inline.Result, error) {
		filename := calleePkg.Fset.File(calleeDecl.Pos()).Name()
		content, err := os.ReadFile(filename)
		if err != nil {
			return nil, err
		}
		callee, err := inline.AnalyzeCallee(
			logf,
			calleePkg.Fset,
			calleePkg.Types,
			calleePkg.TypesInfo,
			calleeDecl,
			content)
		if err != nil {
			return nil, err
		}

		if err := checkTranscode(callee); err != nil {
			return nil, err
		}

		check := checkNoMutation(caller.File)
		defer check()
		return inline.Inline(caller, callee, &inline.Options{Logf: logf})
	}()
	if err != nil {
		if wantRE, ok := want.(*regexp.Regexp); ok {
			if !wantRE.MatchString(err.Error()) {
				return fmt.Errorf("Inline failed with wrong error: %v (want error matching %q)", err, want)
			}
			return nil // expected error
		}
		return fmt.Errorf("Inline failed: %v", err) // success was expected
	}

	// Inline succeeded.
	got, err := applyEdits(caller.Types, caller.File.FileStart, content, res.Edits)
	if err != nil {
		return err
	}
	if want, ok := want.([]byte); ok {
		got = append(bytes.TrimSpace(got), '\n')
		want = append(bytes.TrimSpace(want), '\n')
		// If the "want" file begins "...", it need only be a substring of the "got" result,
		// rather than an exact match.
		if rest, ok := bytes.CutPrefix(want, []byte("...\n")); ok {
			want = rest
			if !bytes.Contains(got, want) {
				return fmt.Errorf("Inline returned wrong output:\n%s\nWant substring:\n%s", got, want)
			}
		} else {
			if diff := diff.Unified("want", "got", string(want), string(got)); diff != "" {
				return fmt.Errorf("Inline returned wrong output:\n-- got --\n%s\n-- want --\n%s\n-- diff --\n%s",
					got, want, diff)
			}
		}
		return nil
	}
	return fmt.Errorf("Inline succeeded unexpectedly: want error matching %q, got <<%s>>", want, got)
}

// findFuncByPosition returns the FuncDecl at the specified (package-agnostic) position.
func findFuncByPosition(pkg *packages.Package, posn token.Position) (*ast.FuncDecl, error) {
	same := func(decl *ast.FuncDecl) bool {
		// We can't rely on columns in export data:
		// some variants replace it with 1.
		// We can't expect file names to have the same prefix.
		// export data for go1.20 std packages have  $GOROOT written in
		// them, so how are we supposed to find the source? Yuck!
		// Ugh. need to samefile? Nope $GOROOT just won't work
		// This is highly client specific anyway.
		posn2 := pkg.Fset.PositionFor(decl.Name.Pos(), false)
		return posn.Filename == posn2.Filename &&
			posn.Line == posn2.Line
	}
	for _, file := range pkg.Syntax {
		for _, decl := range file.Decls {
			if decl, ok := decl.(*ast.FuncDecl); ok && same(decl) {
				return decl, nil
			}
		}
	}
	return nil, fmt.Errorf("can't find FuncDecl at %v in package %q", posn, pkg.PkgPath)
}

// Each callee must declare a function or method named f,
// and each caller must call it.
const funcName = "f"

// A testcase is an item in a table-driven test.
//
// The table-driven tests are less flexible, but enable more compact
// expression of single-package test cases than is possible with the
// txtar notation.
//
// TODO(adonovan): improve coverage of the cross product of each
// strategy with the checklist of concerns enumerated in the package
// doc comment.
type testcase struct {
	descr          string // description; substrings enable test or inliner options (e.g. "IgnoreEffects", "NoPackageClause")
	callee, caller string // Go source files (sans package decl) of caller, callee
	want           string // expected new portion of caller file, or "error: regexp"
}

func TestErrors(t *testing.T) {
	runTests(t, []testcase{
		{
			"Inference of type parameters is not yet supported.",
			`func f[T any](x T) T { return x }`,
			`var _ = f(0)`,
			`error: type parameter inference is not yet supported`,
		},
		{
			"Methods on generic types are not yet supported.",
			`type G[T any] struct{}; func (G[T]) f(x T) T { return x }`,
			`var _ = G[int]{}.f(0)`,
			`error: generic methods not yet supported`,
		},
		{
			"[NoPackageClause] Can't inline a callee using newer Go to a caller using older Go (#75726).",
			"//go:build go1.23\n\npackage p\nfunc f() int { return 0 }",
			"//go:build go1.22\n\npackage p\nvar _ = f()",
			`error: cannot inline call to p.f \(declared using go1.23\) into a file using go1.22`,
		},
	})
}

func TestBasics(t *testing.T) {
	runTests(t, []testcase{
		{
			"Basic",
			`func f(x int) int { return x }`,
			`var _ = f(0)`,
			`var _ = 0`,
		},
		{
			"Empty body, no arg effects.",
			`func f(x, y int) {}`,
			`func _() { f(1, 2) }`,
			`func _() {}`,
		},
		{
			"Empty body, some arg effects.",
			`func f(x, y, z int) {}`,
			`func _() { f(1, recover().(int), 3) }`,
			`func _() { _ = recover().(int) }`,
		},
		{
			"Non-duplicable arguments are not substituted even if pure.",
			`func f(s string, i int) { print(s, s, i, i) }`,
			`func _() { f("hi", 0)  }`,
			`func _() {
	var s string = "hi"
	print(s, s, 0, 0)
}`,
		},
		{
			"Workaround for T(x) misformatting (#63362).",
			`func f(ch <-chan int) { <-ch }`,
			`func _(ch chan int) { f(ch) }`,
			`func _(ch chan int) { <-(<-chan int)(ch) }`,
		},
		{
			// (a regression test for unnecessary braces)
			"In block elision, blank decls don't count when computing name conflicts.",
			`func f(x int) { var _ = x; var _ = 3 }`,
			`func _() { var _ = 1; f(2) }`,
			`func _() {
	var _ = 1
	var _ = 2
	var _ = 3
}`,
		},
		{
			// (a regression test for a missing conversion)
			"Implicit return conversions are inserted in expr-context reduction.",
			`func f(x int) error { return nil }`,
			`func _() { if err := f(0); err != nil {} }`,
			`func _() {
	if err := error(nil); err != nil {
	}
}`,
		},
		{
			"Explicit type parameters.",
			`func f[T any](x T) T { return x }`,
			`var _ = f[int](0)`,
			// TODO(jba): remove the unnecessary conversion.
			`var _ = int(0)`,
		},
	})
}

func TestDuplicable(t *testing.T) {
	t.Run("basic", func(t *testing.T) {
		runTests(t, []testcase{
			{
				"Empty strings are duplicable.",
				`func f(s string) { print(s, s) }`,
				`func _() { f("")  }`,
				`func _() { print("", "") }`,
			},
			{
				"Non-empty string literals are not duplicable.",
				`func f(s string) { print(s, s) }`,
				`func _() { f("hi")  }`,
				`func _() {
	var s string = "hi"
	print(s, s)
}`,
			},
			{
				"Empty array literals are duplicable.",
				`func f(a [2]int) { print(a, a) }`,
				`func _() { f([2]int{})  }`,
				`func _() { print([2]int{}, [2]int{}) }`,
			},
			{
				"Non-empty array literals are not duplicable.",
				`func f(a [2]int) { print(a, a) }`,
				`func _() { f([2]int{1, 2})  }`,
				`func _() {
	var a [2]int = [2]int{1, 2}
	print(a, a)
}`,
			},
			{
				"Empty struct literals are duplicable.",
				`func f(s S) { print(s, s) }; type S struct { x int }`,
				`func _() { f(S{})  }`,
				`func _() { print(S{}, S{}) }`,
			},
			{
				"Non-empty struct literals are not duplicable.",
				`func f(s S) { print(s, s) }; type S struct { x int }`,
				`func _() { f(S{x: 1})  }`,
				`func _() {
	var s S = S{x: 1}
	print(s, s)
}`,
			},
		})
	})

	t.Run("conversions", func(t *testing.T) {
		runTests(t, []testcase{
			{
				"Conversions to integer are duplicable.",
				`func f(i int) { print(i, i) }`,
				`func _() { var i int8 = 1; f(int(i))  }`,
				`func _() { var i int8 = 1; print(int(i), int(i)) }`,
			},
			{
				"Implicit conversions from underlying types are duplicable.",
				`func f(i I) { print(i, i) }; type I int; func print(args ...any) {}`,
				`func _() { f(1)  }`,
				`func _() { print(I(1), I(1)) }`,
			},
			{
				"Conversions to array are duplicable.",
				`func f(a [2]int) { print(a, a) }; type A [2]int`,
				`func _() { var a A; f([2]int(a)) }`,
				`func _() { var a A; print([2]int(a), [2]int(a)) }`,
			},
			{
				"Conversions from array are duplicable.",
				`func f(a A) { print(a, a) }; type A [2]int`,
				`func _() { var a [2]int; f(A(a)) }`,
				`func _() { var a [2]int; print(A(a), A(a)) }`,
			},
			{
				"Conversions from byte slice to string are duplicable.",
				`func f(s string) { print(s, s) }`,
				`func _() { var b []byte; f(string(b)) }`,
				`func _() { var b []byte; print(string(b), string(b)) }`,
			},
			{
				"Conversions from string to byte slice are not duplicable.",
				`func f(b []byte) { print(b, b) }`,
				`func _() { var s string; f([]byte(s)) }`,
				`func _() {
	var s string
	var b []byte = []byte(s)
	print(b, b)
}`,
			},
			{
				"Conversions from string to uint8 slice are not duplicable.",
				`func f(b []uint8) { print(b, b) }`,
				`func _() { var s string; f([]uint8(s)) }`,
				`func _() {
	var s string
	var b []uint8 = []uint8(s)
	print(b, b)
}`,
			},
			{
				"Conversions from string to rune slice are not duplicable.",
				`func f(r []rune) { print(r, r) }`,
				`func _() { var s string; f([]rune(s)) }`,
				`func _() {
	var s string
	var r []rune = []rune(s)
	print(r, r)
}`,
			},
			{
				"Conversions from string to named type with underlying byte slice are not duplicable.",
				`func f(b B) { print(b, b) }; type B []byte`,
				`func _() { var s string; f(B(s)) }`,
				`func _() {
	var s string
	var b B = B(s)
	print(b, b)
}`,
			},
			{
				"Conversions from string to named type of string are duplicable.",
				`func f(s S) { print(s, s) }; type S string`,
				`func _() { var s string; f(S(s)) }`,
				`func _() { var s string; print(S(s), S(s)) }`,
			},
			{
				"Built-in function calls are not duplicable.",
				`func f(i int) { print(i, i) }`,
				`func _() { f(len(""))  }`,
				`func _() {
	var i int = len("")
	print(i, i)
}`,
			},
			{
				"Built-in function calls are not duplicable.",
				`func f(c complex128) { print(c, c) }`,
				`func _() { f(complex(1.0, 2.0)) }`,
				`func _() {
	var c complex128 = complex(1.0, 2.0)
	print(c, c)
}`,
			},
			{
				"Non built-in function calls are not duplicable.",
				`func f(i int) { print(i, i) }
//go:noinline
func f1(i int) int { return i + 1 }`,
				`func _() { f(f1(1))  }`,
				`func _() {
	var i int = f1(1)
	print(i, i)
}`,
			},
			{
				"Conversions between function types are duplicable.",
				`func f(f F) { print(f, f) }; type F func(); func f1() {}`,
				`func _() { f(F(f1))  }`,
				`func _() { print(F(f1), F(f1)) }`,
			},
		})
	})
}

func TestExprStmtReduction(t *testing.T) {
	runTests(t, []testcase{
		{
			"A call in an unrestricted ExprStmt may be replaced by the body stmts.",
			`func f() { var _ = len("") }`,
			`func _() { f() }`,
			`func _() { var _ = len("") }`,
		},
		{
			"ExprStmts in the body of a switch case are unrestricted.",
			`func f() { x := 1; print(x) }`,
			`func _() { switch { case true: f() } }`,
			`func _() {
	switch {
	case true:
		x := 1
		print(x)
	}
}`,
		},
		{
			"ExprStmts in the body of a select case are unrestricted.",
			`func f() { x := 1; print(x) }`,
			`func _() { select { default: f() } }`,
			`func _() {
	select {
	default:
		x := 1
		print(x)
	}
}`,
		},
		{
			"Some ExprStmt contexts are restricted to simple statements.",
			`func f() { var _ = len("") }`,
			`func _(cond bool) { if f(); cond {} }`,
			`func _(cond bool) {
	if func() { var _ = len("") }(); cond {
	}
}`,
		},
		{
			"Braces must be preserved to avoid a name conflict (decl before).",
			`func f() { x := 1; print(x) }`,
			`func _() { x := 2; print(x); f() }`,
			`func _() {
	x := 2
	print(x)
	{
		x := 1
		print(x)
	}
}`,
		},
		{
			"Braces must be preserved to avoid a name conflict (decl after).",
			`func f() { x := 1; print(x) }`,
			`func _() { f(); x := 2; print(x) }`,
			`func _() {
	{
		x := 1
		print(x)
	}
	x := 2
	print(x)
}`,
		},
		{
			"Braces must be preserved to avoid a forward jump across a decl.",
			`func f() { x := 1; print(x) }`,
			`func _() { goto label; f(); label: }`,
			`func _() {
	goto label
	{
		x := 1
		print(x)
	}
label:
}`,
		},
	})
}

func TestPrecedenceParens(t *testing.T) {
	// Ensure that parens are inserted when (and only when) necessary
	// around the replacement for the call expression. (This is a special
	// case in the way the inliner uses a combination of AST formatting
	// for the call and text splicing for the rest of the file.)
	runTests(t, []testcase{
		{
			"Multiplication in addition context (no parens).",
			`func f(x, y int) int { return x * y }`,
			`func _() { _ = 1 + f(2, 3) }`,
			`func _() { _ = 1 + 2*3 }`,
		},
		{
			"Addition in multiplication context (parens).",
			`func f(x, y int) int { return x + y }`,
			`func _() { _ = 1 * f(2, 3) }`,
			`func _() { _ = 1 * (2 + 3) }`,
		},
		{
			"Addition in negation context (parens).",
			`func f(x, y int) int { return x + y }`,
			`func _() { _ = -f(1, 2) }`,
			`func _() { _ = -(1 + 2) }`,
		},
		{
			"Addition in call context (no parens).",
			`func f(x, y int) int { return x + y }`,
			`func _() { println(f(1, 2)) }`,
			`func _() { println(1 + 2) }`,
		},
		{
			"Addition in slice operand context (parens).",
			`func f(x, y string) string { return x + y }`,
			`func _() { _ = f("x",  "y")[1:2] }`,
			`func _() { _ = ("x" + "y")[1:2] }`,
		},
		{
			"String literal in slice operand context (no parens).",
			`func f(x string) string { return x }`,
			`func _() { _ = f("xy")[1:2] }`,
			`func _() { _ = "xy"[1:2] }`,
		},
	})
}

func TestSubstitution(t *testing.T) {
	runTests(t, []testcase{
		{
			"Arg to unref'd param can be eliminated if has no effects.",
			`func f(x, y int) {}; var global int`,
			`func _() { f(0, global) }`,
			`func _() {}`,
		},
		{
			"But not if it may contain last reference to a caller local var.",
			`func f(int) {}`,
			`func _() { var local int; f(local) }`,
			`func _() { var local int; _ = local }`,
		},
		{
			"Arguments that are used are detected",
			`func f(int) {}`,
			`func _() { var local int; _ = local; f(local) }`,
			`func _() { var local int; _ = local }`,
		},
		{
			"Arguments that are used by other arguments are detected",
			`func f(x, y int) { print(x) }`,
			`func _() { var z int; f(z, z) }`,
			`func _() { var z int; print(z) }`,
		},
		{
			"Arguments that are used by other variadic arguments are detected",
			`func f(x int, ys ...int) { print(ys) }`,
			`func _() { var z int; f(z, 1, 2, 3, z) }`,
			`func _() { var z int; print([]int{1, 2, 3, z}) }`,
		},
		{
			"Arguments that are used by other variadic arguments are detected, 2",
			`func f(x int, ys ...int) { print(ys) }`,
			`func _() { var z int; f(z) }`,
			`func _() {
	var z int
	var _ int = z
	print([]int{})
}`,
		},
		{
			"Function parameters are always used",
			`func f(int) {}`,
			`func _() {
	func(local int) {
		f(local)
	}(1)
}`,
			`func _() {
	func(local int) {

	}(1)
}`,
		},
		{
			"Regression test for detection of shadowing in nested functions.",
			`func f(x int) { _ = func() { y := 1; print(y); print(x) } }`,
			`func _(y int) { f(y) } `,
			`func _(y int) {
	var x int = y
	_ = func() { y := 1; print(y); print(x) }
}`,
		},
	})
}

func TestTailCallStrategy(t *testing.T) {
	runTests(t, []testcase{
		{
			"simple",
			`func f() int { return 1 }`,
			`func _() int { return f() }`,
			`func _() int { return 1 }`,
		},
		{
			"void",
			`func f() { println() }`,
			`func _() { f() }`,
			`func _() { println() }`,
		},
		{
			"void with defer", // => literalized
			`func f() { defer f(); println() }`,
			`func _() { f() }`,
			`func _() { func() { defer f(); println() }() }`,
		},
		// Tests for issue #63336:
		{
			"non-trivial return conversion (caller.sig = callee.sig)",
			`func f() error { if true { return nil } else { return e } }; var e struct{error}`,
			`func _() error { return f() }`,
			`func _() error {
	if true {
		return nil
	} else {
		return e
	}
}`,
		},
		{
			"non-trivial return conversion (caller.sig != callee.sig)",
			`func f() error { return E{} }; type E struct{error}`,
			`func _() any { return f() }`,
			`func _() any { return error(E{}) }`,
		},
	})
}

func TestSpreadCalls(t *testing.T) {
	runTests(t, []testcase{
		{
			"Edge case: cannot literalize spread method call.",
			`type I int
 			func g() (I, I)
			func (r I) f(x, y I) I {
				defer g() // force literalization
				return x + y + r
			}`,
			`func _() I { return recover().(I).f(g()) }`,
			`error: can't yet inline spread call to method`,
		},
		{
			"Spread argument evaluated for effect.",
			`func f(int, int) {}; func g() (int, int)`,
			`func _() { f(g())  }`,
			`func _() { _, _ = g() }`,
		},
		{
			"Edge case: receiver and spread argument, both evaluated for effect.",
			`type T int; func (T) f(int, int) {}; func g() (int, int)`,
			`func _() { T(0).f(g())  }`,
			`func _() {
	var (
		_    = T(0)
		_, _ = g()
	)
}`,
		},
		{
			"Spread call in return (#63398).",
			`func f() (int, error) { return 0, nil }`,
			`func _() (int, error) { return f() }`,
			`func _() (int, error) { return 0, nil }`,
		},
	})
}

func TestAssignmentCallStrategy(t *testing.T) {
	runTests(t, []testcase{
		{
			"splice: basic",
			`func f(x int) (int, int) { return x, 2 }`,
			`func _() { x, y := f(1); _, _ = x, y }`,
			`func _() { x, y := 1, 2; _, _ = x, y }`,
		},
		{
			"spread: basic",
			`func f(x int) (any, any) { return g() }; func g() (error, error) { return nil, nil }`,
			`func _() {
	var x any
	x, y := f(0)
	_, _ = x, y
}`,
			`func _() {
	var x any
	var y any
	x, y = g()
	_, _ = x, y
}`,
		},
		{
			"spread: free var conflict",
			`func f(x int) (any, any) { return g(x) }; func g(x int) (int, int) { return x, x }`,
			`func _() {
	y := 2
	{
		var x any
		x, y := f(y)
		_, _ = x, y
	}
}`,
			`func _() {
	y := 2
	{
		var x any
		x, y := func() (any, any) { return g(y) }()
		_, _ = x, y
	}
}`,
		},
		{
			"convert: basic",
			`func f(x int) (int32, int8) { return 1, 2 }`,
			`func _() {
	var x int32
  x, y := f(0)
	_, _ = x, y
}`,
			`func _() {
	var x int32
	x, y := 1, int8(2)
	_, _ = x, y
}`,
		},
		{
			"convert: rune and byte",
			`func f(x int) (rune, byte) { return 0, 0 }`,
			`func _() {
	x, y := f(0)
	_, _ = x, y
}`,
			`func _() {
	x, y := rune(0), byte(0)
	_, _ = x, y
}`,
		},
		{
			"convert: interface conversions",
			`func f(x int) (_, _ error) { return nil, nil }`,
			`func _() {
  x, y := f(0)
	_, _ = x, y
}`,
			`func _() {
	x, y := error(nil), error(nil)
	_, _ = x, y
}`,
		},
		{
			"convert: implicit nil conversions",
			`func f(x int) (_, _ error) { return nil, nil }`,
			`func _() { x, y := f(0); _, _ = x, y }`,
			`func _() { x, y := error(nil), error(nil); _, _ = x, y }`,
		},
		{
			"convert: pruning nil assignments left",
			`func f(x int) (_, _ error) { return nil, nil }`,
			`func _() { _, y := f(0); _ = y }`,
			`func _() { y := error(nil); _ = y }`,
		},
		{
			"convert: pruning nil assignments right",
			`func f(x int) (_, _ error) { return nil, nil }`,
			`func _() { x, _ := f(0); _ = x }`,
			`func _() { x := error(nil); _ = x }`,
		},
		{
			"convert: partial assign",
			`func f(x int) (_, _ error) { return nil, nil }`,
			`func _() {
	var x error
  x, y := f(0)
	_, _ = x, y
}`,
			`func _() {
	var x error
	x, y := nil, error(nil)
	_, _ = x, y
}`,
		},
		{
			"convert: single assignment left",
			`func f() int { return 0 }`,
			`func _() {
	x, y := f(), "hello"
	_, _ = x, y
}`,
			`func _() {
	x, y := 0, "hello"
	_, _ = x, y
}`,
		},
		{
			"convert: single assignment left with conversion",
			`func f() int32 { return 0 }`,
			`func _() {
	x, y := f(), "hello"
	_, _ = x, y
}`,
			`func _() {
	x, y := int32(0), "hello"
	_, _ = x, y
}`,
		},
		{
			"convert: single assignment right",
			`func f() int32 { return 0 }`,
			`func _() {
	x, y := "hello", f()
	_, _ = x, y
}`,
			`func _() {
	x, y := "hello", int32(0)
	_, _ = x, y
}`,
		},
		{
			"convert: single assignment middle",
			`func f() int32 { return 0 }`,
			`func _() {
	x, y, z := "hello", f(), 1.56
	_, _, _ = x, y, z
}`,
			`func _() {
	x, y, z := "hello", int32(0), 1.56
	_, _, _ = x, y, z
}`,
		},
	})
}

func TestVariadic(t *testing.T) {
	runTests(t, []testcase{
		{
			"Variadic cancellation (basic).",
			`func f(args ...any) { defer f(&args); println(args) }`,
			`func _(slice []any) { f(slice...) }`,
			`func _(slice []any) { func() { var args []any = slice; defer f(&args); println(args) }() }`,
		},
		{
			"Variadic cancellation (literalization with parameter elimination).",
			`func f(args ...any) { defer f(); println(args) }`,
			`func _(slice []any) { f(slice...) }`,
			`func _(slice []any) { func() { defer f(); println(slice) }() }`,
		},
		{
			"Variadic cancellation (reduction).",
			`func f(args ...any) { println(args) }`,
			`func _(slice []any) { f(slice...) }`,
			`func _(slice []any) { println(slice) }`,
		},
		{
			"Undo variadic elimination",
			`func f(args ...int) []int { return append([]int{1}, args...) }`,
			`func _(a, b int) { f(a, b) }`,
			`func _(a, b int) { _ = append([]int{1}, a, b) }`,
		},
		{
			"Variadic elimination (literalization).",
			`func f(x any, rest ...any) { defer println(x, rest) }`, // defer => literalization
			`func _() { f(1, 2, 3) }`,
			`func _() { func() { defer println(1, []any{2, 3}) }() }`,
		},
		{
			"Variadic elimination (reduction).",
			`func f(x int, rest ...int) { println(x, rest) }`,
			`func _() { f(1, 2, 3) }`,
			`func _() { println(1, []int{2, 3}) }`,
		},
		{
			"Spread call to variadic (1 arg, 1 param).",
			`func f(rest ...int) { println(rest) }; func g() (a, b int)`,
			`func _() { f(g()) }`,
			`func _() { func(rest ...int) { println(rest) }(g()) }`,
		},
		{
			"Spread call to variadic (1 arg, 2 params).",
			`func f(x int, rest ...int) { println(x, rest) }; func g() (a, b int)`,
			`func _() { f(g()) }`,
			`func _() { func(x int, rest ...int) { println(x, rest) }(g()) }`,
		},
		{
			"Spread call to variadic (1 arg, 3 params).",
			`func f(x, y int, rest ...int) { println(x, y, rest) }; func g() (a, b, c int)`,
			`func _() { f(g()) }`,
			`func _() { func(x, y int, rest ...int) { println(x, y, rest) }(g()) }`,
		},
	})
}

func TestParameterBindingDecl(t *testing.T) {
	runTests(t, []testcase{
		{
			"IncDec counts as assignment.",
			`func f(x int) { x++ }`,
			`func _() { f(1) }`,
			`func _() {
	var x int = 1
	x++
}`,
		},
		{
			"Binding declaration (x, y, z eliminated).",
			`func f(w, x, y any, z int) { println(w, y, z) }; func g(int) int`,
			`func _() { f(g(0), g(1), g(2), g(3)) }`,
			`func _() {
	var w, _ any = g(0), g(1)
	println(w, g(2), g(3))
}`,
		},
		{
			"Reduction of stmt-context call to { return exprs }, with substitution",
			`func f(ch chan int) int { return <-ch }; func g() chan int`,
			`func _() { f(g()) }`,
			`func _() { <-g() }`,
		},
		{
			// Same again, with callee effects:
			"Binding decl in reduction of stmt-context call to { return exprs }",
			`func f(x int) int { return <-h(g(2), x) }; func g(int) int; func h(int, int) chan int`,
			`func _() { f(g(1)) }`,
			`func _() {
	var x int = g(1)
	<-h(g(2), x)
}`,
		},
		{
			"No binding decl due to shadowing of int",
			`func f(int, y any, z int) { defer g(0); println(int, y, z) }; func g(int) int`,
			`func _() { f(g(1), g(2), g(3)) }`,
			`func _() { func(int, y any, z int) { defer g(0); println(int, y, z) }(g(1), g(2), g(3)) }`,
		},
		{
			"An indirect method selection (*x).g acts as a read.",
			`func f(x *T, y any) any { return x.g(y) }; type T struct{}; func (T) g(x any) any { return x }`,
			`func _(x *T) { f(x, recover()) }`,
			`func _(x *T) {
	var y any = recover()
	x.g(y)
}`,
		},
		{
			"A direct method selection x.g is pure.",
			`func f(x *T, y any) any { return x.g(y) }; type T struct{}; func (*T) g(x any) any { return x }`,
			`func _(x *T) { f(x, recover()) }`,
			`func _(x *T) { x.g(recover()) }`,
		},
		{
			"Literalization can make use of a binding decl (all params).",
			`func f(x, y int) int { defer println(); return y + x }; func g(int) int`,
			`func _() { println(f(g(1), g(2))) }`,
			`func _() { println(func() int { var x, y int = g(1), g(2); defer println(); return y + x }()) }`,
		},
		{
			"Literalization can make use of a binding decl (some params).",
			`func f(x, y int) int { z := y + x; defer println(); return z }; func g(int) int`,
			`func _() { println(f(g(1), g(2))) }`,
			`func _() { println(func() int { var x int = g(1); z := g(2) + x; defer println(); return z }()) }`,
		},
		{
			"Literalization can't yet use of a binding decl if named results.",
			`func f(x, y int) (z int) { z = y + x; defer println(); return }; func g(int) int`,
			`func _() { println(f(g(1), g(2))) }`,
			`func _() { println(func(x int) (z int) { z = g(2) + x; defer println(); return }(g(1))) }`,
		},
	})
}

func TestEmbeddedFields(t *testing.T) {
	runTests(t, []testcase{
		{
			"Embedded fields in x.f method selection (direct).",
			`type T int; func (t T) f() { print(t) }; type U struct{ T }`,
			`func _(u U) { u.f() }`,
			`func _(u U) { print(u.T) }`,
		},
		{
			"Embedded fields in x.f method selection (implicit *).",
			`type ( T int; U struct{*T}; V struct {U} ); func (t T) f() { print(t) }`,
			`func _(v V) { v.f() }`,
			`func _(v V) { print(*v.U.T) }`,
		},
		{
			"Embedded fields in x.f method selection (implicit &).",
			`type ( T int; U struct{T}; V struct {U} ); func (t *T) f() { print(t) }`,
			`func _(v V) { v.f() }`,
			`func _(v V) { print(&v.U.T) }`,
		},
		// Now the same tests again with T.f(recv).
		{
			"Embedded fields in T.f method selection.",
			`type T int; func (t T) f() { print(t) }; type U struct{ T }`,
			`func _(u U) { U.f(u) }`,
			`func _(u U) { print(u.T) }`,
		},
		{
			"Embedded fields in T.f method selection (implicit *).",
			`type ( T int; U struct{*T}; V struct {U} ); func (t T) f() { print(t) }`,
			`func _(v V) { V.f(v) }`,
			`func _(v V) { print(*v.U.T) }`,
		},
		{
			"Embedded fields in (*T).f method selection.",
			`type ( T int; U struct{T}; V struct {U} ); func (t *T) f() { print(t) }`,
			`func _(v V) { (*V).f(&v) }`,
			`func _(v V) { print(&(&v).U.T) }`,
		},
		{
			// x is a single-assign var, and x.f does not load through a pointer
			// (despite types.Selection.Indirect=true), so x is pure.
			"No binding decl is required for recv in method-to-method calls.",
			`type T struct{}; func (x *T) f() { g(); print(*x) }; func g()`,
			`func (x *T) _() { x.f() }`,
			`func (x *T) _() {
	g()
	print(*x)
}`,
		},
		{
			"Same, with implicit &recv.",
			`type T struct{}; func (x *T) f() { g(); print(*x) }; func g()`,
			`func (x T) _() { x.f() }`,
			`func (x T) _() {
	{
		var x *T = &x
		g()
		print(*x)
	}
}`,
		},
	})
}

func TestSubstitutionGroups(t *testing.T) {
	runTests(t, []testcase{
		{
			// b -> a
			"Basic",
			`func f(a, b int) { print(a, b) }`,
			`func _() { var a int; f(a, a) }`,
			`func _() { var a int; print(a, a) }`,
		},
		{
			// a <-> b
			"Cocycle",
			`func f(a, b int) { print(a, b) }`,
			`func _() { var a, b int; f(a+b, a+b) }`,
			`func _() { var a, b int; print(a+b, a+b) }`,
		},
		{
			// a <-> b
			// a -> c
			// Don't compute b as substitutable due to bad cycle traversal.
			"Middle cycle",
			`func f(a, b, c int) { var d int; print(a, b, c, d) }`,
			`func _() { var a, b, c, d int; f(a+b+c, a+b, d) }`,
			`func _() {
	var a, b, c, d int
	{
		var a, b, c int = a + b + c, a + b, d
		var d int
		print(a, b, c, d)
	}
}`,
		},
		{
			// a -> b
			// b -> c
			// b -> d
			// c
			//
			// Only c should be substitutable.
			"Singleton",
			`func f(a, b, c, d int) { var e int; print(a, b, c, d, e) }`,
			`func _() { var a, b, c, d, e int; f(a+b, c+d, c, e) }`,
			`func _() {
	var a, b, c, d, e int
	{
		var a, b, d int = a + b, c + d, e
		var e int
		print(a, b, c, d, e)
	}
}`,
		},
	})
}

func TestSubstitutionPreservesArgumentEffectOrder(t *testing.T) {
	runTests(t, []testcase{
		{
			"Arguments have effects, but parameters are evaluated in order.",
			`func f(a, b, c int) { print(a, b, c) }; func g(int) int`,
			`func _() { f(g(1), g(2), g(3)) }`,
			`func _() { print(g(1), g(2), g(3)) }`,
		},
		{
			"Arguments have effects, and parameters are evaluated out of order.",
			`func f(a, b, c int) { print(a, c, b) }; func g(int) int`,
			`func _() { f(g(1), g(2), g(3)) }`,
			`func _() {
	var a, b int = g(1), g(2)
	print(a, g(3), b)
}`,
		},
		{
			"Pure arguments may commute with argument that have effects.",
			`func f(a, b, c int) { print(a, c, b) }; func g(int) int`,
			`func _() { f(g(1), 2, g(3)) }`,
			`func _() { print(g(1), g(3), 2) }`,
		},
		{
			"Impure arguments may commute with each other.",
			`func f(a, b, c, d int) { print(a, c, b, d) }; func g(int) int; var x, y int`,
			`func _() { f(g(1), x, y, g(2)) }`,
			`func _() { print(g(1), y, x, g(2)) }`,
		},
		{
			"Impure arguments do not commute with arguments that have effects (1)",
			`func f(a, b, c, d int) { print(a, c, b, d) }; func g(int) int; var x, y int`,
			`func _() { f(g(1), g(2), y, g(3)) }`,
			`func _() {
	var a, b int = g(1), g(2)
	print(a, y, b, g(3))
}`,
		},
		{
			"Impure arguments do not commute with those that have effects (2).",
			`func f(a, b, c, d int) { print(a, c, b, d) }; func g(int) int; var x, y int`,
			`func _() { f(g(1), y, g(2), g(3)) }`,
			`func _() {
	var a, b int = g(1), y
	print(a, g(2), b, g(3))
}`,
		},
		{
			"Callee effects commute with pure arguments.",
			`func f(a, b, c int) { print(a, c, recover().(int), b) }; func g(int) int`,
			`func _() { f(g(1), 2, g(3)) }`,
			`func _() { print(g(1), g(3), recover().(int), 2) }`,
		},
		{
			"Callee reads may commute with impure arguments.",
			`func f(a, b int) { print(a, x, b) }; func g(int) int; var x, y int`,
			`func _() { f(g(1), y) }`,
			`func _() { print(g(1), x, y) }`,
		},
		{
			"All impure parameters preceding a read hazard must be kept.",
			`func f(a, b, c int) { print(a, b, recover().(int), c) }; var x, y, z int`,
			`func _() { f(x, y, z) }`,
			`func _() {
	var c int = z
	print(x, y, recover().(int), c)
}`,
		},
		{
			"All parameters preceding a write hazard must be kept.",
			`func f(a, b, c int) { print(a, b, recover().(int), c) }; func g(int) int; var x, y, z int`,
			`func _() { f(x, y, g(0))  }`,
			`func _() {
	var a, b, c int = x, y, g(0)
	print(a, b, recover().(int), c)
}`,
		},
		{
			"[W1 R0 W2 W4 R3] -- test case for second iteration of effect loop",
			`func f(a, b, c, d, e int) { print(b, a, c, e, d) }; func g(int) int; var x, y int`,
			`func _() { f(x, g(1), g(2), y, g(3))  }`,
			`func _() {
	var a, b, c, d int = x, g(1), g(2), y
	print(b, a, c, g(3), d)
}`,
		},
		{
			// In this example, the set() call is rejected as a substitution
			// candidate due to a shadowing conflict (z). This must entail that the
			// selection x.y (R) is also rejected, because it is lower numbered.
			//
			// Incidentally this program (which panics when executed) illustrates
			// that although effects occur left-to-right, read operations such
			// as x.y are not ordered wrt writes, depending on the compiler.
			// Changing x.y to identity(x).y forces the ordering and avoids the panic.
			"Hazards with args already rejected (e.g. due to shadowing) are detected too.",
			`func f(x, y int) (z int) { return x + y }; func set[T any](ptr *T, old, new T) int { println(old); *ptr = new; return 0; }`,
			`func _() { x := new(struct{ y int }); z := x; f(x.y, set(&x, z, nil)) }`,
			`func _() {
	x := new(struct{ y int })
	z := x
	{
		var x, y int = x.y, set(&x, z, nil)
		_ = x + y
	}
}`,
		},
		{
			// Rejection of a later parameter for reasons other than callee
			// effects (e.g. escape) may create hazards with lower-numbered
			// parameters that require them to be rejected too.
			"Hazards with already eliminated parameters (variant)",
			`func f(x, y int) { _ = &y }; func g(int) int`,
			`func _() { f(g(1), g(2)) }`,
			`func _() {
	var _, y int = g(1), g(2)
	_ = &y
}`,
		},
		{
			// In this case g(2) is rejected for substitution because it is
			// unreferenced but has effects, so parameter x must also be rejected
			// so that its argument v can be evaluated earlier in the binding decl.
			"Hazards with already eliminated parameters (unreferenced fx variant)",
			`func f(x, y int) { _ = x }; func g(int) int; var v int`,
			`func _() { f(v, g(2)) }`,
			`func _() {
	var x, _ int = v, g(2)
	_ = x
}`,
		},
		{
			"Defer f() evaluates f() before unknown effects",
			`func f(int, y any, z int) { defer println(int, y, z) }; func g(int) int`,
			`func _() { f(g(1), g(2), g(3)) }`,
			`func _() { func() { defer println(g(1), g(2), g(3)) }() }`,
		},
		{
			"Effects are ignored when IgnoreEffects",
			`func f(x, y int) { println(y, x) }; func g(int) int`,
			`func _() { f(g(1), g(2)) }`,
			`func _() { println(g(2), g(1)) }`,
		},
	})
}

func TestNamedResultVars(t *testing.T) {
	runTests(t, []testcase{
		{
			"Stmt-context call to {return g()} that mentions named result.",
			`func f() (x int) { return g(x) }; func g(int) int`,
			`func _() { f() }`,
			`func _() {
	var x int
	g(x)
}`,
		},
		{
			"Ditto, with binding decl again.",
			`func f(y string) (x int) { return x+x+len(y+y) }`,
			`func _() { f(".") }`,
			`func _() {
	var (
		y string = "."
		x int
	)
	_ = x + x + len(y+y)
}`,
		},

		{
			"Ditto, with binding decl (due to repeated y refs).",
			`func f(y string) (x string) { return x+y+y }`,
			`func _() { f(".") }`,
			`func _() {
	var (
		y string = "."
		x string
	)
	_ = x + y + y
}`,
		},
		{
			"Stmt-context call to {return binary} that mentions named result.",
			`func f() (x int) { return x+x }`,
			`func _() { f() }`,
			`func _() {
	var x int
	_ = x + x
}`,
		},
		{
			"Tail call to {return expr} that mentions named result.",
			`func f() (x int) { return x }`,
			`func _() int { return f() }`,
			`func _() int { return func() (x int) { return x }() }`,
		},
		{
			"Tail call to {return} that implicitly reads named result.",
			`func f() (x int) { return }`,
			`func _() int { return f() }`,
			`func _() int { return func() (x int) { return }() }`,
		},
		{
			"Spread-context call to {return expr} that mentions named result.",
			`func f() (x, y int) { return x, y }`,
			`func _() { var _, _ = f() }`,
			`func _() { var _, _ = func() (x, y int) { return x, y }() }`,
		},
		{
			"Shadowing in binding decl for named results => literalization.",
			`func f(y string) (x y) { return x+x+len(y+y) }; type y = int`,
			`func _() { f(".") }`,
			`func _() { func(y string) (x y) { return x + x + len(y+y) }(".") }`,
		},
	})
}

func TestSubstitutionPreservesParameterType(t *testing.T) {
	runTests(t, []testcase{
		{
			"Substitution preserves argument type (#63193).",
			`func f(x int16) { y := x; _ = (*int16)(&y) }`,
			`func _() { f(1) }`,
			`func _() {
	y := int16(1)
	_ = (*int16)(&y)
}`,
		},
		{
			"Same, with non-constant (unnamed to named struct) conversion.",
			`func f(x T) { y := x; _ = (*T)(&y) }; type T struct{}`,
			`func _() { f(struct{}{}) }`,
			`func _() {
	y := T(struct{}{})
	_ = (*T)(&y)
}`,
		},
		{
			"Same, with non-constant (chan to <-chan) conversion.",
			`func f(x T) { y := x; _ = (*T)(&y) }; type T = <-chan int; var ch chan int`,
			`func _() { f(ch) }`,
			`func _() {
	y := T(ch)
	_ = (*T)(&y)
}`,
		},
		{
			"Same, with untyped nil to typed nil conversion.",
			`func f(x *int) { y := x; _ = (**int)(&y) }`,
			`func _() { f(nil) }`,
			`func _() {
	y := (*int)(nil)
	_ = (**int)(&y)
}`,
		},
		{
			"Conversion of untyped int to named type is made explicit.",
			`type T int; func (x T) f() { x.g() }; func (T) g() {}`,
			`func _() { T.f(1) }`,
			`func _() { T(1).g() }`,
		},
		{
			"Implicit reference is made explicit outside of selector",
			`type T int; func (x *T) f() bool { return x == x.id() }; func (x *T) id() *T { return x }`,
			`func _() { var t T; _ = t.f() }`,
			`func _() { var t T; _ = &t == t.id() }`,
		},
		{
			"Implicit parenthesized reference is not made explicit in selector",
			`type T int; func (x *T) f() bool { return x == (x).id() }; func (x *T) id() *T { return x }`,
			`func _() { var t T; _ = t.f() }`,
			`func _() { var t T; _ = &t == (t).id() }`,
		},
		{
			"Implicit dereference is made explicit outside of selector", // TODO(rfindley): avoid unnecessary literalization here
			`type T int; func (x T) f() bool { return x == x.id() }; func (x T) id() T { return x }`,
			`func _() { var t *T; _ = t.f() }`,
			`func _() { var t *T; _ = func() bool { var x T = *t; return x == x.id() }() }`,
		},
		{
			"Check for shadowing error on type used in the conversion.",
			`func f(x T) { _ = &x == (*T)(nil) }; type T int16`,
			`func _() { type T bool; f(1) }`,
			`error: T.*shadowed.*by.*type`,
		},
	})
}

func TestRedundantConversions(t *testing.T) {
	runTests(t, []testcase{
		{
			"Type conversion must be added if the constant is untyped.",
			`func f(i int32) { print(i) }; func print(x any) {}`,
			`func _() { f(1)  }`,
			`func _() { print(int32(1)) }`,
		},
		{
			"Type conversion must not be added if the constant is typed.",
			`func f(i int32) { print(i) }; func print(x any) {}`,
			`func _() { f(int32(1))  }`,
			`func _() { print(int32(1)) }`,
		},
		{
			"No type conversion for argument to interface parameter",
			`type T int; func f(x any) { g(x) }; func g(any) {}`,
			`func _() { f(T(1)) }`,
			`func _() { g(T(1)) }`,
		},
		{
			"No type conversion for parenthesized argument to interface parameter",
			`type T int; func f(x any) { g((x)) }; func g(any) {}`,
			`func _() { f(T(1)) }`,
			`func _() { g((T(1))) }`,
		},
		{
			"Type conversion for argument to type parameter",
			`type T int; func f(x any) { g(x) }; func g[P any](P) {}`,
			`func _() { f(T(1)) }`,
			`func _() { g(any(T(1))) }`,
		},
		{
			"Strip redundant interface conversions",
			`type T interface{ M() }; func f(x any) { g(x) }; func g[P any](P) {}`,
			`func _() { f(T(nil)) }`,
			`func _() { g(any(nil)) }`,
		},
		{
			"No type conversion for argument to variadic interface parameter",
			`type T int; func f(x ...any) { g(x...) }; func g(...any) {}`,
			`func _() { f(T(1)) }`,
			`func _() { g(T(1)) }`,
		},
		{
			"Type conversion for variadic argument",
			`type T int; func f(x ...any) { g(x...) }; func g(...any) {}`,
			`func _() { f([]any{T(1)}...) }`,
			`func _() { g([]any{T(1)}...) }`,
		},
		{
			"Type conversion for argument to interface channel",
			`type T int; var c chan any; func f(x T) { c <- x }`,
			`func _() { f(1) }`,
			`func _() { c <- T(1) }`,
		},
		{
			"No type conversion for argument to concrete channel",
			`type T int32; var c chan T; func f(x T) { c <- x }`,
			`func _() { f(1) }`,
			`func _() { c <- 1 }`,
		},
		{
			"Type conversion for interface map key",
			`type T int; var m map[any]any; func f(x T) { m[x] = 1 }`,
			`func _() { f(1) }`,
			`func _() { m[T(1)] = 1 }`,
		},
		{
			"No type conversion for interface to interface map key",
			`type T int; var m map[any]any; func f(x any) { m[x] = 1 }`,
			`func _() { f(T(1)) }`,
			`func _() { m[T(1)] = 1 }`,
		},
		{
			"No type conversion for concrete map key",
			`type T int; var m map[T]any; func f(x T) { m[x] = 1 }`,
			`func _() { f(1) }`,
			`func _() { m[1] = 1 }`,
		},
		{
			"Type conversion for interface literal key/value",
			`type T int; type m map[any]any; func f(x, y T) { _ = m{x: y} }`,
			`func _() { f(1, 2) }`,
			`func _() { _ = m{T(1): T(2)} }`,
		},
		{
			"No type conversion for concrete literal key/value",
			`type T int; type m map[T]T; func f(x, y T) { _ = m{x: y} }`,
			`func _() { f(1, 2) }`,
			`func _() { _ = m{1: 2} }`,
		},
		{
			"Type conversion for interface literal element",
			`type T int; type s []any; func f(x T) { _ = s{x} }`,
			`func _() { f(1) }`,
			`func _() { _ = s{T(1)} }`,
		},
		{
			"No type conversion for concrete literal element",
			`type T int; type s []T; func f(x T) { _ = s{x} }`,
			`func _() { f(1) }`,
			`func _() { _ = s{1} }`,
		},
		{
			"Type conversion for interface unkeyed struct field",
			`type T int; type s struct{any}; func f(x T) { _ = s{x} }`,
			`func _() { f(1) }`,
			`func _() { _ = s{T(1)} }`,
		},
		{
			"No type conversion for concrete unkeyed struct field",
			`type T int; type s struct{T}; func f(x T) { _ = s{x} }`,
			`func _() { f(1) }`,
			`func _() { _ = s{1} }`,
		},
		{
			"Type conversion for interface field value",
			`type T int; type S struct{ F any }; func f(x T) { _ = S{F: x} }`,
			`func _() { f(1) }`,
			`func _() { _ = S{F: T(1)} }`,
		},
		{
			"No type conversion for concrete field value",
			`type T int; type S struct{ F T }; func f(x T) { _ = S{F: x} }`,
			`func _() { f(1) }`,
			`func _() { _ = S{F: 1} }`,
		},
		{
			"Type conversion for argument to interface channel",
			`type T int; var c chan any; func f(x any) { c <- x }`,
			`func _() { f(T(1)) }`,
			`func _() { c <- T(1) }`,
		},
		{
			"No type conversion for argument to concrete channel",
			`type T int32; var c chan T; func f(x T) { c <- x }`,
			`func _() { f(1) }`,
			`func _() { c <- 1 }`,
		},
		{
			"No type conversion for assignment to an explicit interface type",
			`type T int; func f(x any) { var y any; y = x; _ = y }`,
			`func _() { f(T(1)) }`,
			`func _() {
	var y any
	y = T(1)
	_ = y
}`,
		},
		{
			"No type conversion for short variable assignment to an explicit interface type",
			`type T int; func f(e error) { var err any; i, err := 1, e; _, _ = i, err }`,
			`func _() { f(nil) }`,
			`func _() {
	var err any
	i, err := 1, nil
	_, _ = i, err
}`,
		},
		{
			"No type conversion for initializer of an explicit interface type",
			`type T int; func f(x any) { var y any = x; _ = y }`,
			`func _() { f(T(1)) }`,
			`func _() {
	var y any = T(1)
	_ = y
}`,
		},
		{
			"No type conversion for use as a composite literal key",
			`type T int; func f(x any) { _ = map[any]any{x: 1} }`,
			`func _() { f(T(1)) }`,
			`func _() { _ = map[any]any{T(1): 1} }`,
		},
		{
			"No type conversion for use as a composite literal value",
			`type T int; func f(x any) { _ = []any{x} }`,
			`func _() { f(T(1)) }`,
			`func _() { _ = []any{T(1)} }`,
		},
		{
			"No type conversion for use as a composite literal field",
			`type T int; func f(x any) { _ = struct{ F any }{F: x} }`,
			`func _() { f(T(1)) }`,
			`func _() { _ = struct{ F any }{F: T(1)} }`,
		},
		{
			"No type conversion for use in a send statement",
			`type T int; func f(x any) { var c chan any; c <- x }`,
			`func _() { f(T(1)) }`,
			`func _() {
	var c chan any
	c <- T(1)
}`,
		},
	})
}

func runTests(t *testing.T, tests []testcase) {
	for _, test := range tests {
		t.Run(test.descr, func(t *testing.T) {
			fset := token.NewFileSet()
			mustParse := func(filename string, content any) *ast.File {
				f, err := parser.ParseFile(fset, filename, content, parser.ParseComments|parser.SkipObjectResolution)
				if err != nil {
					t.Fatalf("ParseFile: %v", err)
				}
				return f
			}

			addPackageClause := func(src string) string {
				if !strings.Contains(test.descr, "NoPackageClause") {
					src = "package p\n" + src
				}
				return src
			}

			// Parse callee file and find first func decl named f.
			calleeContent := addPackageClause(test.callee)
			calleeFile := mustParse("callee.go", calleeContent)
			var decl *ast.FuncDecl
			for _, d := range calleeFile.Decls {
				if d, ok := d.(*ast.FuncDecl); ok && d.Name.Name == funcName {
					decl = d
					break
				}
			}
			if decl == nil {
				t.Fatalf("declaration of func %s not found: %s", funcName, test.callee)
			}

			// Parse caller file and find first call to f().
			callerContent := addPackageClause(test.caller)
			callerFile := mustParse("caller.go", callerContent)
			var call *ast.CallExpr
			ast.Inspect(callerFile, func(n ast.Node) bool {
				if n, ok := n.(*ast.CallExpr); ok {
					switch fun := n.Fun.(type) {
					case *ast.SelectorExpr:
						if fun.Sel.Name == funcName {
							call = n
						}
					case *ast.Ident:
						if fun.Name == funcName {
							call = n
						}
					case *ast.IndexExpr:
						if id, ok := fun.X.(*ast.Ident); ok && id.Name == funcName {
							call = n
						}
					case *ast.IndexListExpr:
						if id, ok := fun.X.(*ast.Ident); ok && id.Name == funcName {
							call = n
						}
					}
				}
				return call == nil
			})
			if call == nil {
				t.Fatalf("call to %s not found: %s", funcName, test.caller)
			}

			// Type check both files as one package.
			info := &types.Info{
				Defs:         make(map[*ast.Ident]types.Object),
				Uses:         make(map[*ast.Ident]types.Object),
				Types:        make(map[ast.Expr]types.TypeAndValue),
				Implicits:    make(map[ast.Node]types.Object),
				Selections:   make(map[*ast.SelectorExpr]*types.Selection),
				Scopes:       make(map[ast.Node]*types.Scope),
				FileVersions: make(map[*ast.File]string),
			}
			conf := &types.Config{Error: func(err error) { t.Error(err) }}
			pkg, err := conf.Check("p", fset, []*ast.File{callerFile, calleeFile}, info)
			if err != nil {
				t.Fatal("transformation introduced type errors")
			}

			// Analyze callee and inline call.
			doIt := func() (*inline.Result, error) {
				callee, err := inline.AnalyzeCallee(t.Logf, fset, pkg, info, decl, []byte(calleeContent))
				if err != nil {
					return nil, err
				}
				if err := checkTranscode(callee); err != nil {
					t.Fatal(err)
				}

				caller := &inline.Caller{
					Fset:  fset,
					Types: pkg,
					Info:  info,
					File:  callerFile,
					Call:  call,
				}
				check := checkNoMutation(caller.File)
				defer check()
				return inline.Inline(caller, callee, &inline.Options{
					Logf:          t.Logf,
					IgnoreEffects: strings.Contains(test.descr, "IgnoreEffects"),
				})
			}
			res, err := doIt()

			// Want error?
			if rest, ok := strings.CutPrefix(test.want, "error: "); ok {
				if err == nil {
					t.Fatalf("unexpected success: want error matching %q", rest)
				}
				msg := err.Error()
				if ok, err := regexp.MatchString(rest, msg); err != nil {
					t.Fatalf("invalid regexp: %v", err)
				} else if !ok {
					t.Fatalf("wrong error: %s (want match for %q)", msg, rest)
				}
				return
			}

			// Want success.
			if err != nil {
				t.Fatal(err)
			}

			gotContent, err := applyEdits(pkg, callerFile.FileStart, []byte(callerContent), res.Edits)
			if err != nil {
				t.Fatal(err)
			}

			// Compute a single-hunk line-based diff.
			srcLines := strings.Split(callerContent, "\n")
			gotLines := strings.Split(string(gotContent), "\n")
			for len(srcLines) > 0 && len(gotLines) > 0 &&
				srcLines[0] == gotLines[0] {
				srcLines = srcLines[1:]
				gotLines = gotLines[1:]
			}
			for len(srcLines) > 0 && len(gotLines) > 0 &&
				srcLines[len(srcLines)-1] == gotLines[len(gotLines)-1] {
				srcLines = srcLines[:len(srcLines)-1]
				gotLines = gotLines[:len(gotLines)-1]
			}
			got := strings.Join(gotLines, "\n")

			if strings.TrimSpace(got) != strings.TrimSpace(test.want) {
				t.Fatalf("\nInlining this call:\t%s\nof this callee:    \t%s\nproduced:\n%s\nWant:\n\n%s",
					test.caller,
					test.callee,
					got,
					test.want)
			}

			// Check that resulting code type-checks.
			newCallerFile := mustParse("newcaller.go", gotContent)
			if _, err := conf.Check("p", fset, []*ast.File{newCallerFile, calleeFile}, nil); err != nil {
				t.Fatalf("modified source failed to typecheck: <<%s>>", gotContent)
			}
		})
	}
}

// -- helpers --

// checkNoMutation returns a function that, when called,
// asserts that file was not modified since the checkNoMutation call.
func checkNoMutation(file *ast.File) func() {
	pre := deepHash(file)
	return func() {
		post := deepHash(file)
		if pre != post {
			panic("Inline mutated caller.File")
		}
	}
}

// checkTranscode replaces *callee by the results of gob-encoding and
// then decoding it, to test that these operations are lossless.
func checkTranscode(callee *inline.Callee) error {
	// Perform Gob transcoding so that it is exercised by the test.
	var enc bytes.Buffer
	if err := gob.NewEncoder(&enc).Encode(callee); err != nil {
		return fmt.Errorf("internal error: gob encoding failed: %v", err)
	}
	*callee = inline.Callee{}
	if err := gob.NewDecoder(&enc).Decode(callee); err != nil {
		return fmt.Errorf("internal error: gob decoding failed: %v", err)
	}
	return nil
}

// deepHash computes a cryptographic hash of an ast.Node so that
// if the data structure is mutated, the hash changes.
// It assumes Go variables do not change address.
//
// TODO(adonovan): consider publishing this in the astutil package.
//
// TODO(adonovan): consider a variant that reports where in the tree
// the mutation occurred (obviously at a cost in space).
func deepHash(n ast.Node) any {
	seen := make(map[unsafe.Pointer]bool) // to break cycles

	hasher := sha256.New()
	le := binary.LittleEndian
	writeUint64 := func(v uint64) {
		var bs [8]byte
		le.PutUint64(bs[:], v)
		hasher.Write(bs[:])
	}

	var visit func(reflect.Value)
	visit = func(v reflect.Value) {
		switch v.Kind() {
		case reflect.Pointer:
			ptr := v.UnsafePointer()
			writeUint64(uint64(uintptr(ptr)))
			if !v.IsNil() {
				if !seen[ptr] {
					seen[ptr] = true
					// Skip types we don't handle yet, but don't care about.
					switch v.Interface().(type) {
					case *ast.Scope:
						return // involves a map
					}

					visit(v.Elem())
				}
			}

		case reflect.Struct:
			for i := 0; i < v.Type().NumField(); i++ {
				visit(v.Field(i))
			}

		case reflect.Slice:
			ptr := v.UnsafePointer()
			// We may encounter different slices at the same address,
			// so don't mark ptr as "seen".
			writeUint64(uint64(uintptr(ptr)))
			writeUint64(uint64(v.Len()))
			writeUint64(uint64(v.Cap()))
			for i := 0; i < v.Len(); i++ {
				visit(v.Index(i))
			}

		case reflect.Interface:
			if v.IsNil() {
				writeUint64(0)
			} else {
				rtype := reflect.ValueOf(v.Type()).UnsafePointer()
				writeUint64(uint64(uintptr(rtype)))
				visit(v.Elem())
			}

		case reflect.String:
			writeUint64(uint64(v.Len()))
			hasher.Write([]byte(v.String()))

		case reflect.Int:
			writeUint64(uint64(v.Int()))

		case reflect.Uint:
			writeUint64(uint64(v.Uint()))

		case reflect.Bool, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
			// Bools and fixed width numbers can be handled by binary.Write.
			binary.Write(hasher, le, v.Interface())

		default: // reflect.Array, reflect.Chan, reflect.Func, reflect.Map, reflect.UnsafePointer, reflect.Uintptr
			panic(v) // unreachable in AST
		}
	}
	visit(reflect.ValueOf(n))

	var hash [sha256.Size]byte
	hasher.Sum(hash[:0])
	return hash
}

func TestDeepHash(t *testing.T) {
	// This test reproduces a bug in DeepHash that was encountered during work on
	// the inliner.
	//
	// TODO(rfindley): consider replacing this with a fuzz test.
	id := &ast.Ident{
		NamePos: 2,
		Name:    "t",
	}
	c := &ast.CallExpr{
		Fun: id,
	}
	h1 := deepHash(c)
	id.NamePos = 1
	h2 := deepHash(c)
	if h1 == h2 {
		t.Fatal("bad")
	}
}

// applyEdits transforms content by applying the specified edits
// to the file whose positions are defined by fset), reformatting the file, and
// removing unused imports (using pkg for names of imported packages).
func applyEdits(pkg *types.Package, fileStart token.Pos, content []byte, edits []refactor.Edit) ([]byte, error) {
	dedits := make([]diff.Edit, len(edits))
	for i, edit := range edits {
		dedits[i] = diff.Edit{
			Start: int(edit.Pos - fileStart),
			End:   int(edit.End - fileStart),
			New:   string(edit.NewText),
		}
	}
	got, err := diff.ApplyBytes(content, dedits)
	if err != nil {
		return nil, err
	}
	got, err = driverutil.FormatSourceRemoveImports(pkg, got)
	if err != nil {
		return nil, err
	}
	return []byte(got), nil
}


================================================
FILE: internal/refactor/inline/testdata/assignment-splice.txtar
================================================
This test checks the splice assignment substrategy.

-- go.mod --
module testdata

go 1.20

-- a.go --
package a

func a() (int32, string) {
	return b()
}

func b() (int32, string) {
	return 0, "a"
}

func c() (int, chan<- int) {
	return 0, make(chan int) // nontrivial conversion
}

-- a1.go --
package a

func _() {
	x, y := a() //@ inline(re"a", a1)
}
-- a1 --
package a

func _() {
	x, y := b() //@ inline(re"a", a1)
}
-- a2.go --
package a

func _() {
	var x, y any
	x, y = a() //@ inline(re"a", a2)
}
-- a2 --
package a

func _() {
	var x, y any
	x, y = b() //@ inline(re"a", a2)
}
-- a3.go --
package a

func _() {
	var y chan<- int
	x, y := c() //@ inline(re"c", a3)
}
-- a3 --
package a

func _() {
	var y chan<- int
	x, y := 0, make(chan int) //@ inline(re"c", a3)
}


================================================
FILE: internal/refactor/inline/testdata/assignment.txtar
================================================
Basic tests of inlining a call on the RHS of an assignment.

-- go.mod --
module testdata

go 1.20

-- a/a1.go --
package a

import "testdata/b"

func _() {
	var y int
	x, y := b.B1() //@ inline(re"B", b1)
	_, _ = x, y
}

-- a/a2.go --
package a

import "testdata/b"

func _() {
	var y int
	x, y := b.B2() //@ inline(re"B", b2)
	_, _ = x, y
}

-- a/a3.go --
package a

import "testdata/b"

func _() {
	x, y := b.B3() //@ inline(re"B", b3)
	_, _ = x, y
}

-- a/a4.go --
package a

import "testdata/b"

func _() {
	x, y := b.B4() //@ inline(re"B", b4)
	_, _ = x, y
}

-- b/b.go --
package b

import (
	"testdata/c"
)

func B1() (c.C, int) {
	return 0, 1
}

func B2() (c.C, int) {
	return B1()
}

func B3() (c.C, c.C) {
	return 0, 1
}

-- b/b4.go --
package b

import (
	c1 "testdata/c"
	c2 "testdata/c2"
)

func B4() (c1.C, c2.C) {
	return 0, 1
}

-- c/c.go --
package c

type C int

-- c2/c.go --
package c

type C int

-- b1 --
package a

import "testdata/c"

func _() {
	var y int
	x, y := c.C(0), 1 //@ inline(re"B", b1)
	_, _ = x, y
}
-- b2 --
package a

import "testdata/b"

func _() {
	var y int
	x, y := b.B1() //@ inline(re"B", b2)
	_, _ = x, y
}
-- b3 --
package a

import "testdata/c"

func _() {
	x, y := c.C(0), c.C(1) //@ inline(re"B", b3)
	_, _ = x, y
}

-- b4 --
package a

import c1 "testdata/c"

import c2 "testdata/c2"

func _() {
	x, y := c1.C(0), c2.C(1) //@ inline(re"B", b4)
	_, _ = x, y
}


================================================
FILE: internal/refactor/inline/testdata/basic-err.txtar
================================================
Test of inlining a function that references err.Error,
which is often a special case because it has no position.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "io"

var _ = getError(io.EOF) //@ inline(re"getError", getError)

func getError(err error) string { return err.Error() }

-- getError --
package a

import "io"

var _ = io.EOF.Error() //@ inline(re"getError", getError)

func getError(err error) string { return err.Error() }


================================================
FILE: internal/refactor/inline/testdata/basic-literal.txtar
================================================
Basic tests of inlining by literalization.

The use of defer forces literalization.

recover() is an example of a function with effects,
defeating elimination of parameter x; but parameter
y is eliminated by substitution.

-- go.mod --
module testdata
go 1.12

-- a/a1.go --
package a

func _() {
	add(recover().(int), 2) //@ inline(re"add", add1)
}

func add(x, y int) int { defer print(); return x + y }

-- add1 --
package a

func _() {
	func() int { var x int = recover().(int); defer print(); return x + 2 }() //@ inline(re"add", add1)
}

func add(x, y int) int { defer print(); return x + y }


================================================
FILE: internal/refactor/inline/testdata/basic-reduce.txtar
================================================
Most basic test of inlining by reduction.

-- go.mod --
module testdata
go 1.12

-- a/a0.go --
package a

var _ = zero() //@ inline(re"zero", zero)

func zero() int { return 0 }

-- zero --
package a

var _ = 0 //@ inline(re"zero", zero)

func zero() int { return 0 }

-- a/a1.go --
package a

func _() {
	one := 1
	add(one, 2) //@ inline(re"add", add1)
}

func add(x, y int) int { return x + y }

-- add1 --
package a

func _() {
	one := 1
	_ = one + 2 //@ inline(re"add", add1)
}

func add(x, y int) int { return x + y }

-- a/a2.go --
package a

var _ = add(len(""), 2) //@ inline(re"add", add2)

-- add2 --
package a

var _ = len("") + 2 //@ inline(re"add", add2)



================================================
FILE: internal/refactor/inline/testdata/cgo.txtar
================================================
Test that attempts to inline with caller or callee in a cgo-generated
file are rejected. (This is just a special case of rejecting generated files.)

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

/*
static void f() {}
*/
import "C"

func a() {
	C.f() //@ inline(re"f", re"cannot inline cgo-generated functions")
	g()   //@ inline(re"g", re`cannot inline calls from generated files`)
}

func g() {
	println()
}

-- a/a2.go --
package a

func b() {
	a() //@ inline(re"a", re"cannot inline cgo-generated functions")
}

func c() {
	b() //@ inline(re"b", result)
}

-- result --
package a

func b() {
	a() //@ inline(re"a", re"cannot inline cgo-generated functions")
}

func c() {
	a() //@ inline(re"b", result)
}


================================================
FILE: internal/refactor/inline/testdata/comments.txtar
================================================
Test of (lack of) comment preservation by inlining,
whether by literalization or reduction.

Comment handling was better in an earlier implementation
based on byte-oriented file surgery; switching to AST
manipulation (though better in all other respects) was
a regression. The underlying problem of AST comment fidelity
is Go issue #20744.

-- go.mod --
module testdata
go 1.12

-- a/f.go --
package a

func _() {
	f() //@ inline(re"f", f)
}

func f() {
	// a
	/* b */ g() /* c */
	// d
}

-- f --
package a

func _() {
	g() //@ inline(re"f", f)
}

func f() {
	// a
	/* b */
	g() /* c */
	// d
}

-- a/g.go --
package a

func _() {
	println(g()) //@ inline(re"g", g)
}

func g() int { return 1 /*hello*/ + /*there*/ 1 }

-- g --
package a

func _() {
	println(1 + 1) //@ inline(re"g", g)
}

func g() int { return 1 /*hello*/ + /*there*/ 1 }


================================================
FILE: internal/refactor/inline/testdata/crosspkg-selfref.txtar
================================================
A self-reference counts as a free reference,
so that it gets properly package-qualified as needed.
(Regression test for a bug.)

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"

func _() {
	b.F(1) //@ inline(re"F", output)
}

-- b/b.go --
package b

func F(x int) {
	F(x + 2)
}

-- output --
package a

import "testdata/b"

func _() {
	b.F(1 + 2) //@ inline(re"F", output)
}


================================================
FILE: internal/refactor/inline/testdata/crosspkg.txtar
================================================
Test of cross-package inlining.
The first case creates a new import,
the second reuses an existing one.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

// This comment does not migrate.

import (
	"fmt"
	"testdata/b"
)

// Nor this one.

func A() {
	fmt.Println()
	b.B1() //@ inline(re"B1", b1result)
	b.B2() //@ inline(re"B2", b2result)
	b.B3() //@ inline(re"B3", b3result)
}

-- b/b.go --
package b

import "testdata/c"
import "testdata/d"
import "fmt"

func B1() { c.C() }
func B2() { fmt.Println() }
func B3() { e.E() } // (note that "testdata/d" points to package e)

-- c/c.go --
package c

func C() {}

-- d/d.go --
package e // <- this package name intentionally mismatches the path

func E() {}

-- b1result --
package a

// This comment does not migrate.

import (
	"fmt"
	"testdata/b"
	"testdata/c"
)

// Nor this one.

func A() {
	fmt.Println()
	c.C()  //@ inline(re"B1", b1result)
	b.B2() //@ inline(re"B2", b2result)
	b.B3() //@ inline(re"B3", b3result)
}

-- b2result --
package a

// This comment does not migrate.

import (
	"fmt"
	"testdata/b"
)

// Nor this one.

func A() {
	fmt.Println()
	b.B1()        //@ inline(re"B1", b1result)
	fmt.Println() //@ inline(re"B2", b2result)
	b.B3()        //@ inline(re"B3", b3result)
}
-- b3result --
package a

// This comment does not migrate.

import (
	"fmt"
	"testdata/b"
	e "testdata/d"
)

// Nor this one.

func A() {
	fmt.Println()
	b.B1() //@ inline(re"B1", b1result)
	b.B2() //@ inline(re"B2", b2result)
	e.E()  //@ inline(re"B3", b3result)
}


================================================
FILE: internal/refactor/inline/testdata/dotimport.txtar
================================================
Test of inlining a function that uses a dot import.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

func A() {}

-- b/b.go --
package b

import . "testdata/a"

func B() { A() }

-- c/c.go --
package c

import "testdata/b"

func _() {
	b.B() //@ inline(re"B", result)
}

-- result --
package c

import "testdata/a"

func _() {
	a.A() //@ inline(re"B", result)
}


================================================
FILE: internal/refactor/inline/testdata/embed.txtar
================================================
Test of implicit field selections in method calls.

The two level wrapping T -> unexported -> U is required
to exercise the implicit selections exportedness check;
with only a single level, the receiver declaration in
"func (unexported) F()" would fail the earlier
unexportedness check.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"

func _(x b.T) {
	x.F() //@ inline(re"F", re"in x.F, implicit reference to unexported field .unexported cannot be made explicit")
}

-- b/b.go --
package b

type T struct { unexported }
type unexported struct { U }
type U struct{}
func (U) F() {}


================================================
FILE: internal/refactor/inline/testdata/empty-body.txtar
================================================
Test of elimination of calls to functions with completely empty bodies.
The arguments must still be evaluated and their results discarded.
The number of discard blanks must match the type, not the syntax (see 2-ary f).
If there are no arguments, the entire call is eliminated.

We cannot eliminate some pure argument expressions because they
may contain the last reference to a local variable.

-- go.mod --
module testdata
go 1.12

-- a/a0.go --
package a

func _() {
	empty() //@ inline(re"empty", empty0)
}

func empty(...any) {}

-- empty0 --
package a

func _() {
	//@ inline(re"empty", empty0)
}

func empty(...any) {}

-- a/a1.go --
package a

func _(ch chan int) {
	empty(f()) //@ inline(re"empty", empty1)
}

func f() (int, int)

-- empty1 --
package a

func _(ch chan int) {
	_, _ = f() //@ inline(re"empty", empty1)
}

func f() (int, int)

-- a/a2.go --
package a

func _(ch chan int) {
	empty(-1, ch, len(""), g(), <-ch) //@ inline(re"empty", empty2)
}

func g() int

-- empty2 --
package a

func _(ch chan int) {
	_ = []any{-1, ch, len(""), g(), <-ch} //@ inline(re"empty", empty2)
}

func g() int

-- a/a3.go --
package a

func _() {
	new(T).empty() //@ inline(re"empty", empty3)
}

type T int

func (T) empty() int {}

-- empty3 --
package a

func _() {
	//@ inline(re"empty", empty3)
}

type T int

func (T) empty() int {}

-- a/a4.go --
package a

func _() {
	var x T
	x.empty() //@ inline(re"empty", empty4)
}

-- empty4 --
package a

func _() {
	var x T
	_ = x //@ inline(re"empty", empty4)
}

-- a/a5.go --
package a

func _() {
	go empty() //@ inline(re"empty", empty5)
}

func empty() {}
-- empty5 --
package a

func _() {
	go func() {}() //@ inline(re"empty", empty5)
}

func empty() {}


================================================
FILE: internal/refactor/inline/testdata/err-basic.txtar
================================================
Basic errors:
- Inlining of generic functions is not yet supported.

We can't express tests for the error resulting from inlining a
conversion T(x), a call to a literal func(){}(), a call to a
func-typed var, or a call to an interface method, since all of these
cause the test driver to fail to locate the callee, so
it doesn't even reach the Indent function.

-- go.mod --
module testdata
go 1.12

-- a/nobody.go --
package a

func _() {
	g() //@ inline(re"g", re"has no body")
}

func g()


================================================
FILE: internal/refactor/inline/testdata/err-shadow-builtin.txtar
================================================
Failures to inline because callee references a builtin that
is shadowed by caller.

-- go.mod --
module testdata
go 1.18

-- a/nil.go --
package a

func _() {
	const nil = 1
	_ = f() //@ inline(re"f", re"nil.*shadowed.*by.*const.*line 4")
}

func f() *int { return nil }
-- a/nil-type-param.go --
package a

func _[nil any]() {
	_ = f() //@ inline(re"f", re"nil.*shadowed.*by.*typename.*line 3")
}

-- a/nil-typename.go --
package a

func _[nil any]() {
	_ = f() //@ inline(re"f", re"nil.*shadowed.*by.*typename.*line 3")
}

-- a/append.go --
package a

func _() {
	type append int
	g(nil) //@ inline(re"g", re"append.*shadowed.*by.*typename.*line 4")
}

func g(x []int) { _ = append(x, x...) }

-- a/type.go --
package a

func _() {
	type int uint8
	_ = h(0) //@ inline(re"h", re"int.*shadowed.*by.*typename.*line 4")
}

func h(x int) int { return x + 1 }


================================================
FILE: internal/refactor/inline/testdata/err-shadow-pkg.txtar
================================================
Test of failure to inline because callee references a
package-level decl that is shadowed by caller.

Observe that the first call to f can be inlined because
the shadowing has not yet occurred; but the second call
to f is within the scope of the local constant v.

-- go.mod --
module testdata
go 1.18

-- a/a.go --
package a

func _() {
	f() //@ inline(re"f", result)
	const v = 1
	f() //@ inline(re"f", re"v.*shadowed.*by.*const.*line 5")
}

func _[v any]() {
	f() //@ inline(re"f", re"v.*shadowed.*by.*typename.*line 9")
}

func f() int { return v }

var v int

-- result --
package a

func _() {
	_ = v //@ inline(re"f", result)
	const v = 1
	f() //@ inline(re"f", re"v.*shadowed.*by.*const.*line 5")
}

func _[v any]() {
	f() //@ inline(re"f", re"v.*shadowed.*by.*typename.*line 9")
}

func f() int { return v }

var v int


================================================
FILE: internal/refactor/inline/testdata/err-unexported.txtar
================================================
Errors from attempting to import a function from another
package whose body refers to unexported declarations.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

func A1() { b() }
func b() {}

func A2() { var x T; print(x.f) }
type T struct { f int }

func A3() { _ = &T{f: 0} }

func A4() { _ = &T{0} }

-- b/b.go --
package b

import "testdata/a"

func _() {
	a.A1() //@ inline(re"A1", re`body refers to non-exported b`)
	a.A2() //@ inline(re"A2", re`body refers to non-exported \(testdata/a.T\).f`)
	a.A3() //@ inline(re"A3", re`body refers to non-exported \(testdata/a.T\).f`)
	a.A4() //@ inline(re"A4", re`body refers to non-exported \(testdata/a.T\).f`)
}


================================================
FILE: internal/refactor/inline/testdata/exprstmt.txtar
================================================
Inlining an expression into an ExprStmt.
Call and receive expressions can be inlined directly
(though calls to only some builtins can be reduced).
All other expressions are inlined as "_ = expr".

-- go.mod --
module testdata
go 1.12

-- a/call.go --
package a

func _() {
	call() //@ inline(re"call", call)
}

func call() int { return recv() }

-- call --
package a

func _() {
	recv() //@ inline(re"call", call)
}

func call() int { return recv() }

-- a/recv.go --
package a

func _() {
	recv() //@ inline(re"recv", recv)
}

func recv() int { return <-(chan int)(nil) }

-- recv --
package a

func _() {
	<-(chan int)(nil) //@ inline(re"recv", recv)
}

func recv() int { return <-(chan int)(nil) }

-- a/constant.go --
package a

func _() {
	constant() //@ inline(re"constant", constant)
}

func constant() int { return 0 }

-- constant --
package a

func _() {
	_ = 0 //@ inline(re"constant", constant)
}

func constant() int { return 0 }

-- a/builtin.go --
package a

func _() {
	builtin() //@ inline(re"builtin", builtin)
}

func builtin() int { return len("") }

-- builtin --
package a

func _() {
	_ = len("") //@ inline(re"builtin", builtin)
}

func builtin() int { return len("") }

-- a/copy.go --
package a

func _() {
	_copy() //@ inline(re"copy", copy)
}

func _copy() int { return copy([]int(nil), []int(nil)) }

-- copy --
package a

func _() {
	copy([]int(nil), []int(nil)) //@ inline(re"copy", copy)
}

func _copy() int { return copy([]int(nil), []int(nil)) }



================================================
FILE: internal/refactor/inline/testdata/generic.txtar
================================================
Inlining a call to a generic function.

a1: explicit type args, no shadowing
a2: the call uses type inference
a3: the type argument is shadowed in the callee
a4: ditto, with a more complicated arg
a5: a free identifier in the callee is captured by a global
    in the caller's scope (covered elsewhere; verifying for generics)
-- go.mod --
module testdata
go 1.18

-- a/a1.go --
package a

func _() {
	f[int](1) //@ inline(re"f", a1)
}

func f[T any](x T) { print(x) }
-- a1 --
...
func _() {
	print(int(1)) //@ inline(re"f", a1)
}

-- a/a1a.go --
package a

func _() {
	f[([]int)]([]int{1}) //@ inline(re"f", a1a)
}

func f[T any](x T) { print(x) }
-- a1a --
...
func _() {
	print(([]int)([]int{1})) //@ inline(re"f", a1a)
}

-- a/a2.go --
package a

func _() {
	f(1) //@ inline(re"f", re"cannot inline.*type.*inference")
}

-- a/a3.go --
package a

func _() {
	g[int]() //@ inline(re"g", re"cannot inline:.*shadow")
}

func g[T any]() {
	type int bool
	var x T
	print(x)
}

-- a/a4.go --
package a

func _() {
	g[map[int]string]()  //@ inline(re"g", re"cannot inline:.*shadow")
}

-- a/a5.go --
package a

import "testdata/b"

type bool int

func _() {
	b.H[int]() //@ inline(re"H", re"cannot inline.*shadowed")
}
-- b/b.go --
package b

func H[T comparable]() {
	var x map[T]bool
	print(x)
}

-- a/a6.go --
package a

type G[T any] struct{}

func (G[T]) f(x T) { print(x) }

func _() {
	G[int]{}.f[bool]() //@ inline(re"f", re"generic methods not yet supported")
}


================================================
FILE: internal/refactor/inline/testdata/import-comments.txtar
================================================
This file checks various handling of comments when adding imports.

-- go.mod --
module testdata
go 1.12

-- a/empty.go --
package a // This is package a.

func _() {
	a() //@ inline(re"a", empty)
}

-- empty --
package a // This is package a.

import "testdata/b"

func _() {
	b.B() //@ inline(re"a", empty)
}
-- a/existing.go --
package a // This is package a.

// This is an import block.
import (
	// This is an import of io.
	"io"

	// This is an import of c.
	"testdata/c" // yes, of c
)

var (
	// This is an io.Writer.
	_ io.Writer
	// This is c.C
	_ c.C
)

func _() {
	a() //@ inline(re"a", existing)
}

-- existing --
package a // This is package a.

// This is an import block.
import (
	// This is an import of io.
	"io"
	"testdata/b"

	// This is an import of c.
	"testdata/c" // yes, of c
)

var (
	// This is an io.Writer.
	_ io.Writer
	// This is c.C
	_ c.C
)

func _() {
	b.B() //@ inline(re"a", existing)
}

-- a/noparens.go --
package a // This is package a.

// This is an import of c.
import "testdata/c"

func _() {
	var _ c.C
	a() //@ inline(re"a", noparens)
}

-- noparens --
package a // This is package a.

import "testdata/b"

// This is an import of c.
import "testdata/c"

func _() {
	var _ c.C
	b.B() //@ inline(re"a", noparens)
}

-- a/a.go --
package a

// This is an import of b.
import "testdata/b"

func a() {
	// This is a call to B.
	b.B()
}

-- b/b.go --
package b

func B() {}

-- c/c.go --
package c

type C int


================================================
FILE: internal/refactor/inline/testdata/import-comments2.txtar
================================================
Regression test for migration of comments in deleted imports (#67336).

-- go.mod --
module testdata
go 1.20

-- define/my/typ/foo.go --
package typ
type T int

-- some/other/pkg/foo.go --
package pkg
import "context"
import "testdata/define/my/typ"
func Foo(typ.T) context.Context{ return nil }

-- one/more/pkg/foo.go --
package pkg
func Bar() {}

-- to/be/inlined/foo.go --
package inlined

import "context"
import "testdata/some/other/pkg"
import "testdata/define/my/typ"

// inlineme
func Baz(ctx context.Context) context.Context {
	return pkg.Foo(typ.T(5))
}

-- b/c/foo.go --
package c
import (
	"context"
	"testdata/to/be/inlined"
	"testdata/one/more/pkg"
)

const (
	// This is a constant
	someConst = 5
)

func foo() {
	inlined.Baz(context.TODO()) //@inline(re"Baz", out)
	pkg.Bar()
}

-- out --
package c

import (
	"context"
	"testdata/define/my/typ"
	pkg0 "testdata/some/other/pkg"

	"testdata/one/more/pkg"
)

const (
	// This is a constant
	someConst = 5
)

func foo() {
	var _ context.Context = context.TODO()
	pkg0.Foo(typ.T(5)) //@inline(re"Baz", out)
	pkg.Bar()
}


================================================
FILE: internal/refactor/inline/testdata/import-preserve-local-pkgname.txtar
================================================
Test that when choosing local package names, we prefer the
name used by the callee over a disambiguating numeric suffix.

-- go.mod --
module example.com
go 1.19

-- main/main.go --
package main

import stringutil "example.com/string/util"
import "example.com/util"

func main() {
	util.A() //@ inline(re"A", result)
	stringutil.B()
}

-- util/util.go --
package util

import stringutil "example.com/string/util"
import urlutil "example.com/url/util"

func A() {
	stringutil.A()
	urlutil.A()
}

-- string/util/util.go --
package util

func A() {
}

func B() {
}

-- url/util/util.go --
package util

func A() {
}

-- result --
package main

import urlutil "example.com/url/util"

import stringutil "example.com/string/util"

func main() {
	stringutil.A()
	urlutil.A() //@ inline(re"A", result)
	stringutil.B()
}


================================================
FILE: internal/refactor/inline/testdata/import-rename.txtar
================================================
Regtest for https://github.com/golang/go/issues/67281

-- go.mod --
module example.com
go 1.19

-- main/main.go --
package main

import "example.com/a"

func main() {
	a.A() //@ inline(re"A", result)
}

-- a/a.go --
package a

import "example.com/other/a"

func A() {
	a.A()
}

-- other/a/a.go --
package a

func A() {
}

-- result --
package main

import "example.com/other/a"

func main() {
	a.A() //@ inline(re"A", result)
}


================================================
FILE: internal/refactor/inline/testdata/import-shadow-1.txtar
================================================
This file is identical to import-shadow.txtar except
that the imports in a/a.go are not grouped.
That is unusual, since goimports and related tools
form groups.

The result of inlining (bresult) also looks strange,
but again, goimports would fix it up.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"
import "log"

func A() {
	const log = "shadow"
	b.B() //@ inline(re"B", bresult)
}

var _ log.Logger

-- b/b.go --
package b

import "log"

func B() {
	log.Printf("")
}

-- bresult --
package a

import log0 "log"

import "log"

func A() {
	const log = "shadow"
	log0.Printf("") //@ inline(re"B", bresult)
}

var _ log.Logger


================================================
FILE: internal/refactor/inline/testdata/import-shadow-2.txtar
================================================
See import-shadow.txtar for a description.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"

var x b.T

func A(b int) {
	x.F() //@ inline(re"F", fresult)
}

-- b/b.go --
package b

type T struct{}

func (T) F() {
	One()
	Two()
}

func One() {}
func Two() {}

-- fresult --
package a

import b0 "testdata/b"

import "testdata/b"

var x b.T

func A(b int) {
	b0.One()
	b0.Two() //@ inline(re"F", fresult)
}

-- d/d.go --
package d

import "testdata/e"

func D() {
	const log = "shadow"
	e.E() //@ inline(re"E", eresult)
}

-- e/e.go --
package e

import "log"

func E() {
	log.Printf("")
}

-- eresult --
package d

import log0 "log"

func D() {
	const log = "shadow"
	log0.Printf("") //@ inline(re"E", eresult)
}


================================================
FILE: internal/refactor/inline/testdata/import-shadow.txtar
================================================
Just because a package (e.g. log) is imported by the caller,
and the name log is in scope, doesn't mean the name in scope
refers to the package: it could be locally shadowed.

In all three scenarios in this file and import-shadow-2.txtar, a renaming
import with a fresh name is added because the usual name is locally
shadowed: in cases 1, 2 an existing import is shadowed by (respectively)
a local constant, parameter; in case 3 there is no existing import.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import (
	"testdata/b"
	"log"
)

func A() {
	const log = "shadow"
	b.B() //@ inline(re"B", bresult)
}

var _ log.Logger

-- b/b.go --
package b

import "log"

func B() {
	log.Printf("")
}

-- bresult --
package a

import (
	log0 "log"

	"log"
)

func A() {
	const log = "shadow"
	log0.Printf("") //@ inline(re"B", bresult)
}

var _ log.Logger


================================================
FILE: internal/refactor/inline/testdata/internal.txtar
================================================
Test of inlining a function that references an
internal package that is not accessible to the caller.

(c -> b -> b/internal/a)

-- go.mod --
module testdata
go 1.12

-- b/internal/a/a.go --
package a

func A() {}

-- b/b.go --
package b

import "testdata/b/internal/a"

func B() { a.A() }

-- c/c.go --
package c

import "testdata/b"

func _() {
	b.B() //@ inline(re"B", re`body refers to inaccessible package "testdata/b/internal/a"`)
}


================================================
FILE: internal/refactor/inline/testdata/issue62667.txtar
================================================
Regression test for #62667: the callee's reference to Split
was blindly qualified to path.Split even though the imported
PkgName path is shadowed by the parameter of the same name.

The defer is to defeat reduction of the call and
substitution of the path parameter by g().

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/path"

func A() {
	path.Dir(g()) //@ inline(re"Dir", result)
}

func g() string

-- path/path.go --
package path

func Dir(path string) {
	defer func(){}()
	Split(path)
}

func Split(string) {}

-- result --
package a

import path0 "testdata/path"

func A() {
	func() { var path string = g(); defer func() {}(); path0.Split(path) }() //@ inline(re"Dir", result)
}

func g() string

================================================
FILE: internal/refactor/inline/testdata/issue63298.txtar
================================================
Regression test for #63298: inlining a function that
depends on two packages with the same name leads
to duplicate PkgNames.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

func _() {
	a2() //@ inline(re"a2", result)
}

-- a/a2.go --
package a

import "testdata/b"
import anotherb "testdata/another/b"

func a2() {
	b.B()
	anotherb.B()
}

-- b/b.go --
package b

func B() {}

-- b/another/b.go --
package b

func B() {}

-- result --
package a

import "testdata/b"

import anotherb "testdata/another/b"

func _() {
	b.B()
	anotherb.B() //@ inline(re"a2", result)
}


================================================
FILE: internal/refactor/inline/testdata/issue69441.txtar
================================================
This test checks that variadic elimination does not cause a semantic change due
to creation of a non-nil empty slice instead of a nil slice due to missing
variadic arguments.

-- go.mod --
module testdata
go 1.12

-- foo/foo.go --
package foo
import "fmt"

func F(is ...int) {
	if is == nil {
		fmt.Println("is is nil")
	} else {
		fmt.Println("is is not nil")
	}
}

func G(is ...int) { F(is...) }

func main() {
	G() //@ inline(re"G", G)
}

-- G --
package foo

import "fmt"

func F(is ...int) {
	if is == nil {
		fmt.Println("is is nil")
	} else {
		fmt.Println("is is not nil")
	}
}

func G(is ...int) { F(is...) }

func main() {
	F() //@ inline(re"G", G)
}


================================================
FILE: internal/refactor/inline/testdata/issue69442.txtar
================================================
This test checks that we don't introduce unnecessary (&v) or (*ptr) operations
when calling a method on an addressable receiver.

-- go.mod --
module testdata

go 1.20

-- main.go --
package foo
type T int

func (*T) F() {}

func (t *T) G() { t.F() }

func main() {
	var t T
	t.G() //@ inline(re"G", inline)
}

-- inline --
package foo

type T int

func (*T) F() {}

func (t *T) G() { t.F() }

func main() {
	var t T
	t.F() //@ inline(re"G", inline)
}


================================================
FILE: internal/refactor/inline/testdata/line-directives.txtar
================================================
Test of line directives in caller and caller.
Neither should have any effect on inlining.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "testdata/b"

func A() {
//line b2.go:3:3
	b.F() //@ inline(re"F", result)
}

-- b/b.go --
package b

//line b2.go:1:1
func F() { println("hi") }

-- b/b2.go --
package b

func NotWhatYouWereLookingFor() {}

-- result --
package a

func A() {
//line b2.go:3:3
	println("hi") //@ inline(re"F", result)
}


================================================
FILE: internal/refactor/inline/testdata/method.txtar
================================================
Test of inlining a method call.

The call to (*T).g0 implicitly takes the address &x, and
the call to T.h implicitly dereferences the argument *ptr.

The f1/g1 methods have parameters, exercising the
splicing of the receiver into the parameter list.
Notice that the unnamed parameters become named.

-- go.mod --
module testdata
go 1.12

-- a/f0.go --
package a

type T int

func (recv T) f0() { println(recv) }

func _(x T) {
	x.f0() //@ inline(re"f0", f0)
}

-- f0 --
package a

type T int

func (recv T) f0() { println(recv) }

func _(x T) {
	println(x) //@ inline(re"f0", f0)
}

-- a/g0.go --
package a

func (recv *T) g0() { println(recv) }

func _(x T) {
	x.g0() //@ inline(re"g0", g0)
}

-- g0 --
package a

func (recv *T) g0() { println(recv) }

func _(x T) {
	println(&x) //@ inline(re"g0", g0)
}

-- a/f1.go --
package a

func (recv T) f1(int, int) { println(recv) }

func _(x T) {
	x.f1(1, 2) //@ inline(re"f1", f1)
}

-- f1 --
package a

func (recv T) f1(int, int) { println(recv) }

func _(x T) {
	println(x) //@ inline(re"f1", f1)
}

-- a/g1.go --
package a

func (recv *T) g1(int, int) { println(recv) }

func _(x T) {
	x.g1(1, 2) //@ inline(re"g1", g1)
}

-- g1 --
package a

func (recv *T) g1(int, int) { println(recv) }

func _(x T) {
	println(&x) //@ inline(re"g1", g1)
}

-- a/h.go --
package a

func (T) h() int { return 1 }

func _() {
	var ptr *T
	ptr.h() //@ inline(re"h", h)
}

-- h --
package a

func (T) h() int { return 1 }

func _() {
	var ptr *T
	var _ T = *ptr
	_ = 1 //@ inline(re"h", h)
}

-- a/i.go --
package a

func (T) i() int { return 1 }

func _() {
	(*T).i(nil) //@ inline(re"i", i)
}

-- i --
package a

func (T) i() int { return 1 }

func _() {
	_ = 1 //@ inline(re"i", i)
}


================================================
FILE: internal/refactor/inline/testdata/multistmt-body.txtar
================================================
Tests of reduction of calls to multi-statement bodies.

a1: reduced to a block with a parameter binding decl.
   (Parameter x can't be substituted by z without a shadowing conflict.)

a2: reduced with parameter substitution (no shadowing).

a3: literalized, because of the return statement.

-- go.mod --
module testdata
go 1.12

-- a/a1.go --
package a

func _() {
	z := 1
	f(z, 2) //@ inline(re"f", out1)
}

func f(x, y int) {
	z := 1
	print(x + y + z)
}

-- out1 --
package a

func _() {
	z := 1
	{
		var x int = z
		z := 1
		print(x + 2 + z)
	} //@ inline(re"f", out1)
}

func f(x, y int) {
	z := 1
	print(x + y + z)
}

-- a/a2.go --
package a

func _() {
	a := 1
	f(a, 2) //@ inline(re"f", out2)
}

-- out2 --
package a

func _() {
	a := 1
	z := 1
	print(a + 2 + z) //@ inline(re"f", out2)
}

-- a/a3.go --
package a

func _() {
	a := 1
	g(a, 2) //@ inline(re"g", out3)
}

func g(x, y int) int {
	z := 1
	return x + y + z
}

-- out3 --
package a

func _() {
	a := 1
	func() int { z := 1; return a + 2 + z }() //@ inline(re"g", out3)
}

func g(x, y int) int {
	z := 1
	return x + y + z
}


================================================
FILE: internal/refactor/inline/testdata/n-ary.txtar
================================================
Tests of various n-ary result function cases.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

func _() {
	println(f1()) //@ inline(re"f1", f1)
}

func f1() (int, int) { return 1, 1 }

-- f1 --
package a

func _() {
	println(1, 1) //@ inline(re"f1", f1)
}

func f1() (int, int) { return 1, 1 }

-- b/b.go --
package b

func _() {
	f2() //@ inline(re"f2", f2)
}

func f2() (int, int) { return 2, 2 }

-- f2 --
package b

func _() {
	_, _ = 2, 2 //@ inline(re"f2", f2)
}

func f2() (int, int) { return 2, 2 }

-- c/c.go --
package c

func _() {
	_, _ = f3() //@ inline(re"f3", f3)
}

func f3() (int, int) { return f3A() }
func f3A() (x, y int)

-- f3 --
package c

func _() {
	_, _ = f3A() //@ inline(re"f3", f3)
}

func f3() (int, int) { return f3A() }
func f3A() (x, y int)

-- d/d.go --
package d

func _() {
	println(-f4()) //@ inline(re"f4", f4)
}

func f4() int { return 2 + 2 }

-- f4 --
package d

func _() {
	println(-(2 + 2)) //@ inline(re"f4", f4)
}

func f4() int { return 2 + 2 }
-- e/e.go --
package e

func _() {
	switch {
	case true:
		a, b := f5() //@ inline(re"f5", f5)
		_, _ = a, b
	}
}

func f5() (int, int) { return 2, 2}

-- f5 --
package e

func _() {
	switch {
	case true:
		a, b := 2, 2 //@ inline(re"f5", f5)
		_, _ = a, b
	}
}

func f5() (int, int) { return 2, 2 }


================================================
FILE: internal/refactor/inline/testdata/newexpr.txtar
================================================
Regression test for https://go.dev/issue/76287:
ensure that inlining a function that wraps go1.26's new(expr)
correctly inserts a conversion as needed, just as it would for a
declared generic function equivalent to 'new'.

- f uses a declared _new(expr) function.
- g uses the built-in new(expr) function.

-- go.mod --
module testdata
go 1.26

-- common.go --
package p

func _new[T any](x T) *T { return &x }

-- f.go --
package p

func f(x int64) *int64 { return _new(x) }

var _ *int64 = f(42) //@ inline(re"f", f)

-- g.go --
package p

func g(x int64) *int64 { return new(x) }

var _ *int64 = g(42) //@ inline(re"g", g)

-- f --
package p

func f(x int64) *int64 { return _new(x) }

var _ *int64 = _new(int64(42)) //@ inline(re"f", f)

-- g --
package p

func g(x int64) *int64 { return new(x) }

var _ *int64 = new(int64(42)) //@ inline(re"g", g)


================================================
FILE: internal/refactor/inline/testdata/param-subst.txtar
================================================
Test of parameter substitution.

-- go.mod --
module testdata
go 1.12

-- a/a0.go --
package a

var _ = add(2, 1+1) //@ inline(re"add", add)

func add(x, y int) int { return x + 2*y }

-- add --
package a

var _ = 2 + 2*(1+1) //@ inline(re"add", add)

func add(x, y int) int { return x + 2*y }

================================================
FILE: internal/refactor/inline/testdata/revdotimport.txtar
================================================
Test of inlining a function into a context that already
dot-imports the necessary additional import.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

func A() {}

-- b/b.go --
package b

import "testdata/a"

func B() { a.A() }

-- c/c.go --
package c

import . "testdata/a"
import "testdata/b"

func _() {
	A()
	b.B() //@ inline(re"B", result)
}

-- result --
package c

import "testdata/a"

import . "testdata/a"

func _() {
	A()
	a.A() //@ inline(re"B", result)
}


================================================
FILE: internal/refactor/inline/testdata/std-internal.txtar
================================================

std packages are a special case of the internal package check.

This test assumes that syscall.ByteSliceFromString refers to internal/bytealg.

-- go.mod --
module testdata
go 1.12

-- a/a.go --
package a

import "syscall"

var _, _ = syscall.ByteSliceFromString("") //@ inline(re"ByteSliceFromString", re`inaccessible package "internal/bytealg"`)


================================================
FILE: internal/refactor/inline/testdata/substgroups.txtar
================================================
This test checks that parameter shadowing is avoided for substitution groups,
as well as the examples of recursive pruning of these groups based on falcon
and effects analysis.

-- go.mod --
module testdata

go 1.20

-- falcon.go --
package a

var a [3]int

func falcon(x, y, z int) {
	_ = x + a[y+z]
}

func _() {
	var y int
	const x, z = 1, 2
	falcon(y, x, z) //@ inline(re"falcon", falcon)
}

-- falcon --
package a

var a [3]int

func falcon(x, y, z int) {
	_ = x + a[y+z]
}

func _() {
	var y int
	const x, z = 1, 2
	{
		var x, y, z int = y, x, z
		_ = x + a[y+z]
	} //@ inline(re"falcon", falcon)
}

-- effects.go --
package a

func effects(w, x, y, z int) {
	_ = x + w + y + z
}

func _() {
  v := 0
  w := func() int { v++; return 0 }
  x := func() int { v++; return 0 }
  y := func() int { v++; return 0 }
	effects(x(), w(), y(), x()) //@ inline(re"effects", effects)
}

-- effects --
package a

func effects(w, x, y, z int) {
	_ = x + w + y + z
}

func _() {
	v := 0
	w := func() int { v++; return 0 }
	x := func() int { v++; return 0 }
	y := func() int { v++; return 0 }
	{
		var w, x, y, z int = x(), w(), y(), x()
		_ = x + w + y + z
	} //@ inline(re"effects", effects)
}

-- negative.go --
package a

func _() {
	i := -1
	if negative1(i, i) { //@ inline(re"negative1", negative1)
		i := 0
		_ = i
	}
}

func negative1(i, j int) bool {
	return negative2(j, i)
}

func negative2(i, j int) bool {
	return i < 0
}

-- negative1 --
package a

func _() {
	i := -1
	if negative2(i, i) { //@ inline(re"negative1", negative1)
		i := 0
		_ = i
	}
}

func negative1(i, j int) bool {
	return negative2(j, i)
}

func negative2(i, j int) bool {
	return i < 0
}



================================================
FILE: internal/refactor/inline/testdata/tailcall.txtar
================================================
Reduction of parameterless tail-call to functions.

1. a0 (sum) is reduced, despite the complexity of the callee.

2. a1 (conflict) is not reduced, because the caller and callee have
   intersecting sets of labels.

3. a2 (usesResult) is not reduced, because it refers to a result variable.

-- go.mod --
module testdata
go 1.12

-- a/a0.go --
package a

func _() int {
	return sum(1, 2) //@ inline(re"sum", sum)
}

func sum(lo, hi int) int {
	total := 0
start:
	for i := lo; i <= hi; i++ {
		total += i
		if i == 6 {
			goto start
		} else if i == 7 {
			return -1
		}
	}
	return total
}

-- sum --
package a

func _() int {
	total := 0
start:
	for i := 1; i <= 2; i++ {
		total += i
		if i == 6 {
			goto start
		} else if i == 7 {
			return -1
		}
	}
	return total //@ inline(re"sum", sum)
}

func sum(lo, hi int) int {
	total := 0
start:
	for i := lo; i <= hi; i++ {
		total += i
		if i == 6 {
			goto start
		} else if i == 7 {
			return -1
		}
	}
	return total
}

-- a/a1.go --
package a

func _() int {
	hello:
	return conflict(1, 2) //@ inline(re"conflict", conflict)
	goto hello
}

func conflict(lo, hi int) int {
hello:
	return lo + hi
}

-- conflict --
package a

func _() int {
hello:
	return func() int {
	hello:
		return 1 + 2
	}() //@ inline(re"conflict", conflict)
	goto hello
}

func conflict(lo, hi int) int {
hello:
	return lo + hi
}

-- a/a2.go --
package a

func _() int {
	return usesResult(1, 2) //@ inline(re"usesResult", usesResult)
}

func usesResult(lo, hi int) (z int) {
	z = y + x
	return
}

-- usesResult --
package a

func _() int {
	return func() (z int) { z = y + x; return }() //@ inline(re"usesResult", usesResult)
}

func usesResult(lo, hi int) (z int) {
	z = y + x
	return
}



================================================
FILE: internal/refactor/inline/util.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package inline

// This file defines various common helpers.

import (
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"reflect"
	"strings"

	"golang.org/x/tools/internal/typeparams"
)

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}

func btoi(b bool) int {
	if b {
		return 1
	} else {
		return 0
	}
}

func offsetOf(fset *token.FileSet, pos token.Pos) int {
	return fset.PositionFor(pos, false).Offset
}

// objectKind returns an object's kind (e.g. var, func, const, typename).
func objectKind(obj types.Object) string {
	return strings.TrimPrefix(strings.ToLower(reflect.TypeOf(obj).String()), "*types.")
}

// within reports whether pos is within the half-open interval [n.Pos, n.End).
func within(pos token.Pos, n ast.Node) bool {
	return n.Pos() <= pos && pos < n.End()
}

// trivialConversion reports whether it is safe to omit the implicit
// value-to-variable conversion that occurs in argument passing or
// result return. The only case currently allowed is converting from
// untyped constant to its default type (e.g. 0 to int).
//
// The reason for this check is that converting from A to B to C may
// yield a different result than converting A directly to C: consider
// 0 to int32 to any.
//
// trivialConversion under-approximates trivial conversions, as unfortunately
// go/types does not record the type of an expression *before* it is implicitly
// converted, and therefore it cannot distinguish typed constant
// expressions from untyped constant expressions. For example, in the
// expression `c + 2`, where c is a uint32 constant, trivialConversion does not
// detect that the default type of this expression is actually uint32, not untyped
// int.
//
// We could, of course, do better here by reverse engineering some of go/types'
// constant handling. That may or may not be worthwhile.
//
// Example: in func f() int32 { return 0 },
// the type recorded for 0 is int32, not untyped int;
// although it is Identical to the result var,
// the conversion is non-trivial.
func trivialConversion(fromValue constant.Value, from, to types.Type) bool {
	if fromValue != nil {
		var defaultType types.Type
		switch fromValue.Kind() {
		case constant.Bool:
			defaultType = types.Typ[types.Bool]
		case constant.String:
			defaultType = types.Typ[types.String]
		case constant.Int:
			defaultType = types.Typ[types.Int]
		case constant.Float:
			defaultType = types.Typ[types.Float64]
		case constant.Complex:
			defaultType = types.Typ[types.Complex128]
		default:
			return false
		}
		return types.Identical(defaultType, to)
	}
	return types.Identical(from, to)
}

func checkInfoFields(info *types.Info) {
	assert(info.Defs != nil, "types.Info.Defs is nil")
	assert(info.Implicits != nil, "types.Info.Implicits is nil")
	assert(info.Scopes != nil, "types.Info.Scopes is nil")
	assert(info.Selections != nil, "types.Info.Selections is nil")
	assert(info.Types != nil, "types.Info.Types is nil")
	assert(info.Uses != nil, "types.Info.Uses is nil")
	assert(info.FileVersions != nil, "types.Info.FileVersions is nil")
}

// intersects reports whether the maps' key sets intersect.
func intersects[K comparable, T1, T2 any](x map[K]T1, y map[K]T2) bool {
	if len(x) > len(y) {
		return intersects(y, x)
	}
	for k := range x {
		if _, ok := y[k]; ok {
			return true
		}
	}
	return false
}

// convert returns syntax for the conversion T(x).
func convert(T, x ast.Expr) *ast.CallExpr {
	// The formatter generally adds parens as needed,
	// but before go1.22 it had a bug (#63362) for
	// channel types that requires this workaround.
	if ch, ok := T.(*ast.ChanType); ok && ch.Dir == ast.RECV {
		T = &ast.ParenExpr{X: T}
	}
	return &ast.CallExpr{
		Fun:  T,
		Args: []ast.Expr{x},
	}
}

// isPointer reports whether t's core type is a pointer.
func isPointer(t types.Type) bool {
	return is[*types.Pointer](typeparams.CoreType(t))
}

// indirectSelection is like seln.Indirect() without bug #8353.
func indirectSelection(seln *types.Selection) bool {
	// Work around bug #8353 in Selection.Indirect when Kind=MethodVal.
	if seln.Kind() == types.MethodVal {
		tArg, indirect := effectiveReceiver(seln)
		if indirect {
			return true
		}

		tParam := seln.Obj().Type().Underlying().(*types.Signature).Recv().Type()
		return isPointer(tArg) && !isPointer(tParam) // implicit *
	}

	return seln.Indirect()
}

// effectiveReceiver returns the effective type of the method
// receiver after all implicit field selections (but not implicit * or
// & operations) have been applied.
//
// The boolean indicates whether any implicit field selection was indirect.
func effectiveReceiver(seln *types.Selection) (types.Type, bool) {
	assert(seln.Kind() == types.MethodVal, "not MethodVal")
	t := seln.Recv()
	indices := seln.Index()
	indirect := false
	for _, index := range indices[:len(indices)-1] {
		if isPointer(t) {
			indirect = true
			t = typeparams.MustDeref(t)
		}
		t = typeparams.CoreType(t).(*types.Struct).Field(index).Type()
	}
	return t, indirect
}


================================================
FILE: internal/refactor/refactor.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package refactor provides operators to compute common textual edits
// for refactoring tools.
//
// This package should not use features of the analysis API other than [Edit].
package refactor

import (
	"fmt"
	"go/token"
	"go/types"
)

// FreshName returns the name of an identifier that is undefined
// at the specified position, based on the preferred name.
//
// export/use freshName in go/analysis/passes/modernize/modernize.go if you want
// to generate a fresh name only when necessary (i.e., there is both an existing
// declaration and some free reference to the name within a narrower scope)
func FreshName(scope *types.Scope, pos token.Pos, preferred string) string {
	newName := preferred
	for i := 0; ; i++ {
		if _, obj := scope.LookupParent(newName, pos); obj == nil {
			break // fresh
		}
		newName = fmt.Sprintf("%s%d", preferred, i)
	}
	return newName
}


================================================
FILE: internal/robustio/copyfiles.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The copyfiles script copies the contents of the internal cmd/go robustio
// package to the current directory, with adjustments to make it build.
//
// NOTE: In retrospect this script got out of hand, as we have to perform
// various operations on the package to get it to build at old Go versions. If
// in the future it proves to be flaky, delete it and just copy code manually.
package main

import (
	"bytes"
	"go/build/constraint"
	"go/scanner"
	"go/token"
	"log"
	"os"
	"path/filepath"
	"runtime"
	"strings"
)

func main() {
	dir := filepath.Join(runtime.GOROOT(), "src", "cmd", "go", "internal", "robustio")

	entries, err := os.ReadDir(dir)
	if err != nil {
		log.Fatalf("reading the robustio dir: %v", err)
	}

	// Collect file content so that we can validate before copying.
	fileContent := make(map[string][]byte)
	windowsImport := []byte("\t\"internal/syscall/windows\"\n")
	foundWindowsImport := false
	for _, entry := range entries {
		if strings.HasSuffix(entry.Name(), ".go") {
			pth := filepath.Join(dir, entry.Name())
			content, err := os.ReadFile(pth)
			if err != nil {
				log.Fatalf("reading %q: %v", entry.Name(), err)
			}

			// Replace the use of internal/syscall/windows.ERROR_SHARING_VIOLATION
			// with a local constant.
			if entry.Name() == "robustio_windows.go" && bytes.Contains(content, windowsImport) {
				foundWindowsImport = true
				content = bytes.Replace(content, windowsImport, nil, 1)
				content = bytes.Replace(content, []byte("windows.ERROR_SHARING_VIOLATION"), []byte("ERROR_SHARING_VIOLATION"), -1)
			}

			// Replace os.ReadFile with os.ReadFile (for 1.15 and older). We
			// attempt to match calls (via the '('), to avoid matching mentions of
			// os.ReadFile in comments.
			//
			// TODO(rfindley): once we (shortly!) no longer support 1.15, remove
			// this and break the build.
			if bytes.Contains(content, []byte("os.ReadFile(")) {
				content = bytes.Replace(content, []byte("\"os\""), []byte("\"io/ioutil\"\n\t\"os\""), 1)
				content = bytes.Replace(content, []byte("os.ReadFile("), []byte("os.ReadFile("), -1)
			}

			// Add +build constraints, for 1.16.
			content = addPlusBuildConstraints(content)

			fileContent[entry.Name()] = content
		}
	}

	if !foundWindowsImport {
		log.Fatal("missing expected import of internal/syscall/windows in robustio_windows.go")
	}

	for name, content := range fileContent {
		if err := os.WriteFile(name, content, 0644); err != nil {
			log.Fatalf("writing %q: %v", name, err)
		}
	}
}

// addPlusBuildConstraints splices in +build constraints for go:build
// constraints encountered in the source.
//
// Gopls still builds at Go 1.16, which requires +build constraints.
func addPlusBuildConstraints(src []byte) []byte {
	var s scanner.Scanner
	fset := token.NewFileSet()
	file := fset.AddFile("", fset.Base(), len(src))
	s.Init(file, src, nil /* no error handler */, scanner.ScanComments)

	result := make([]byte, 0, len(src))
	lastInsertion := 0
	for {
		pos, tok, lit := s.Scan()
		if tok == token.EOF {
			break
		}
		if tok == token.COMMENT {
			if c, err := constraint.Parse(lit); err == nil {
				plusBuild, err := constraint.PlusBuildLines(c)
				if err != nil {
					log.Fatalf("computing +build constraint for %q: %v", lit, err)
				}
				insertAt := file.Offset(pos) + len(lit)
				result = append(result, src[lastInsertion:insertAt]...)
				result = append(result, []byte("\n"+strings.Join(plusBuild, "\n"))...)
				lastInsertion = insertAt
			}
		}
	}
	result = append(result, src[lastInsertion:]...)
	return result
}


================================================
FILE: internal/robustio/gopls_windows.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package robustio

import "syscall"

// The robustio package is copied from cmd/go/internal/robustio, a package used
// by the go command to retry known flaky operations on certain operating systems.

//go:generate go run copyfiles.go

// Since the gopls module cannot access internal/syscall/windows, copy a
// necessary constant.
const ERROR_SHARING_VIOLATION syscall.Errno = 32


================================================
FILE: internal/robustio/robustio.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package robustio wraps I/O functions that are prone to failure on Windows,
// transparently retrying errors up to an arbitrary timeout.
//
// Errors are classified heuristically and retries are bounded, so the functions
// in this package do not completely eliminate spurious errors. However, they do
// significantly reduce the rate of failure in practice.
//
// If so, the error will likely wrap one of:
// The functions in this package do not completely eliminate spurious errors,
// but substantially reduce their rate of occurrence in practice.
package robustio

import "time"

// Rename is like os.Rename, but on Windows retries errors that may occur if the
// file is concurrently read or overwritten.
//
// (See golang.org/issue/31247 and golang.org/issue/32188.)
func Rename(oldpath, newpath string) error {
	return rename(oldpath, newpath)
}

// ReadFile is like os.ReadFile, but on Windows retries errors that may
// occur if the file is concurrently replaced.
//
// (See golang.org/issue/31247 and golang.org/issue/32188.)
func ReadFile(filename string) ([]byte, error) {
	return readFile(filename)
}

// RemoveAll is like os.RemoveAll, but on Windows retries errors that may occur
// if an executable file in the directory has recently been executed.
//
// (See golang.org/issue/19491.)
func RemoveAll(path string) error {
	return removeAll(path)
}

// IsEphemeralError reports whether err is one of the errors that the functions
// in this package attempt to mitigate.
//
// Errors considered ephemeral include:
//   - syscall.ERROR_ACCESS_DENIED
//   - syscall.ERROR_FILE_NOT_FOUND
//   - internal/syscall/windows.ERROR_SHARING_VIOLATION
//
// This set may be expanded in the future; programs must not rely on the
// non-ephemerality of any given error.
func IsEphemeralError(err error) bool {
	return isEphemeralError(err)
}

// A FileID uniquely identifies a file in the file system.
//
// If GetFileID(name1) returns the same ID as GetFileID(name2), the two file
// names denote the same file.
// A FileID is comparable, and thus suitable for use as a map key.
type FileID struct {
	device, inode uint64
}

// GetFileID returns the file system's identifier for the file, and its
// modification time.
// Like os.Stat, it reads through symbolic links.
func GetFileID(filename string) (FileID, time.Time, error) { return getFileID(filename) }


================================================
FILE: internal/robustio/robustio_darwin.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package robustio

import (
	"errors"
	"syscall"
)

const errFileNotFound = syscall.ENOENT

// isEphemeralError returns true if err may be resolved by waiting.
func isEphemeralError(err error) bool {
	var errno syscall.Errno
	if errors.As(err, &errno) {
		return errno == errFileNotFound
	}
	return false
}


================================================
FILE: internal/robustio/robustio_flaky.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build windows || darwin

package robustio

import (
	"errors"
	"math/rand"
	"os"
	"syscall"
	"time"
)

const arbitraryTimeout = 2000 * time.Millisecond

// retry retries ephemeral errors from f up to an arbitrary timeout
// to work around filesystem flakiness on Windows and Darwin.
func retry(f func() (err error, mayRetry bool)) error {
	var (
		bestErr     error
		lowestErrno syscall.Errno
		start       time.Time
		nextSleep   time.Duration = 1 * time.Millisecond
	)
	for {
		err, mayRetry := f()
		if err == nil || !mayRetry {
			return err
		}

		var errno syscall.Errno
		if errors.As(err, &errno) && (lowestErrno == 0 || errno < lowestErrno) {
			bestErr = err
			lowestErrno = errno
		} else if bestErr == nil {
			bestErr = err
		}

		if start.IsZero() {
			start = time.Now()
		} else if d := time.Since(start) + nextSleep; d >= arbitraryTimeout {
			break
		}
		time.Sleep(nextSleep)
		nextSleep += time.Duration(rand.Int63n(int64(nextSleep)))
	}

	return bestErr
}

// rename is like os.Rename, but retries ephemeral errors.
//
// On Windows it wraps os.Rename, which (as of 2019-06-04) uses MoveFileEx with
// MOVEFILE_REPLACE_EXISTING.
//
// Windows also provides a different system call, ReplaceFile,
// that provides similar semantics, but perhaps preserves more metadata. (The
// documentation on the differences between the two is very sparse.)
//
// Empirical error rates with MoveFileEx are lower under modest concurrency, so
// for now we're sticking with what the os package already provides.
func rename(oldpath, newpath string) (err error) {
	return retry(func() (err error, mayRetry bool) {
		err = os.Rename(oldpath, newpath)
		return err, isEphemeralError(err)
	})
}

// readFile is like os.ReadFile, but retries ephemeral errors.
func readFile(filename string) ([]byte, error) {
	var b []byte
	err := retry(func() (err error, mayRetry bool) {
		b, err = os.ReadFile(filename)

		// Unlike in rename, we do not retry errFileNotFound here: it can occur
		// as a spurious error, but the file may also genuinely not exist, so the
		// increase in robustness is probably not worth the extra latency.
		return err, isEphemeralError(err) && !errors.Is(err, errFileNotFound)
	})
	return b, err
}

func removeAll(path string) error {
	return retry(func() (err error, mayRetry bool) {
		err = os.RemoveAll(path)
		return err, isEphemeralError(err)
	})
}


================================================
FILE: internal/robustio/robustio_other.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !windows && !darwin

package robustio

import (
	"os"
)

func rename(oldpath, newpath string) error {
	return os.Rename(oldpath, newpath)
}

func readFile(filename string) ([]byte, error) {
	return os.ReadFile(filename)
}

func removeAll(path string) error {
	return os.RemoveAll(path)
}

func isEphemeralError(err error) bool {
	return false
}


================================================
FILE: internal/robustio/robustio_plan9.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build plan9

package robustio

import (
	"os"
	"syscall"
	"time"
)

func getFileID(filename string) (FileID, time.Time, error) {
	fi, err := os.Stat(filename)
	if err != nil {
		return FileID{}, time.Time{}, err
	}
	dir := fi.Sys().(*syscall.Dir)
	return FileID{
		device: uint64(dir.Type)<<32 | uint64(dir.Dev),
		inode:  dir.Qid.Path,
	}, fi.ModTime(), nil
}


================================================
FILE: internal/robustio/robustio_posix.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !windows && !plan9

package robustio

import (
	"os"
	"syscall"
	"time"
)

func getFileID(filename string) (FileID, time.Time, error) {
	fi, err := os.Stat(filename)
	if err != nil {
		return FileID{}, time.Time{}, err
	}
	stat := fi.Sys().(*syscall.Stat_t)
	return FileID{
		device: uint64(stat.Dev), // (int32 on darwin, uint64 on linux)
		inode:  stat.Ino,
	}, fi.ModTime(), nil
}


================================================
FILE: internal/robustio/robustio_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package robustio_test

import (
	"os"
	"path/filepath"
	"runtime"
	"testing"
	"time"

	"golang.org/x/tools/internal/robustio"
)

func checkOSLink(t *testing.T, err error) {
	if err == nil {
		return
	}

	t.Helper()
	switch runtime.GOOS {
	case "aix", "darwin", "dragonfly", "freebsd", "illumos", "linux", "netbsd", "openbsd", "solaris":
		// Non-mobile OS known to always support os.Symlink and os.Link.
		t.Fatal(err)
	default:
		t.Skipf("skipping due to error on %v: %v", runtime.GOOS, err)
	}
}

func TestFileInfo(t *testing.T) {
	// A nonexistent file has no ID.
	nonexistent := filepath.Join(t.TempDir(), "nonexistent")
	if _, _, err := robustio.GetFileID(nonexistent); err == nil {
		t.Fatalf("GetFileID(nonexistent) succeeded unexpectedly")
	}

	// A regular file has an ID.
	real := filepath.Join(t.TempDir(), "real")
	if err := os.WriteFile(real, nil, 0644); err != nil {
		t.Fatalf("can't create regular file: %v", err)
	}
	realID, realMtime, err := robustio.GetFileID(real)
	if err != nil {
		t.Fatalf("can't get ID of regular file: %v", err)
	}

	// Sleep so that we get a new mtime for subsequent writes.
	time.Sleep(2 * time.Second)

	// A second regular file has a different ID.
	real2 := filepath.Join(t.TempDir(), "real2")
	if err := os.WriteFile(real2, nil, 0644); err != nil {
		t.Fatalf("can't create second regular file: %v", err)
	}
	real2ID, real2Mtime, err := robustio.GetFileID(real2)
	if err != nil {
		t.Fatalf("can't get ID of second regular file: %v", err)
	}
	if realID == real2ID {
		t.Errorf("realID %+v == real2ID %+v", realID, real2ID)
	}
	if realMtime.Equal(real2Mtime) {
		t.Errorf("realMtime %v == real2Mtime %v", realMtime, real2Mtime)
	}

	// A symbolic link has the same ID as its target.
	t.Run("symlink", func(t *testing.T) {
		symlink := filepath.Join(t.TempDir(), "symlink")
		checkOSLink(t, os.Symlink(real, symlink))

		symlinkID, symlinkMtime, err := robustio.GetFileID(symlink)
		if err != nil {
			t.Fatalf("can't get ID of symbolic link: %v", err)
		}
		if realID != symlinkID {
			t.Errorf("realID %+v != symlinkID %+v", realID, symlinkID)
		}
		if !realMtime.Equal(symlinkMtime) {
			t.Errorf("realMtime %v != symlinkMtime %v", realMtime, symlinkMtime)
		}
	})

	// Two hard-linked files have the same ID.
	t.Run("hardlink", func(t *testing.T) {
		hardlink := filepath.Join(t.TempDir(), "hardlink")
		checkOSLink(t, os.Link(real, hardlink))

		hardlinkID, hardlinkMtime, err := robustio.GetFileID(hardlink)
		if err != nil {
			t.Fatalf("can't get ID of hard link: %v", err)
		}
		if realID != hardlinkID {
			t.Errorf("realID %+v != hardlinkID %+v", realID, hardlinkID)
		}
		if !realMtime.Equal(hardlinkMtime) {
			t.Errorf("realMtime %v != hardlinkMtime %v", realMtime, hardlinkMtime)
		}
	})
}


================================================
FILE: internal/robustio/robustio_windows.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package robustio

import (
	"errors"
	"syscall"
	"time"
)

const errFileNotFound = syscall.ERROR_FILE_NOT_FOUND

// isEphemeralError returns true if err may be resolved by waiting.
func isEphemeralError(err error) bool {
	var errno syscall.Errno
	if errors.As(err, &errno) {
		switch errno {
		case syscall.ERROR_ACCESS_DENIED,
			syscall.ERROR_FILE_NOT_FOUND,
			ERROR_SHARING_VIOLATION:
			return true
		}
	}
	return false
}

// Note: it may be convenient to have this helper return fs.FileInfo, but
// implementing this is actually quite involved on Windows. Since we only
// currently use mtime, keep it simple.
func getFileID(filename string) (FileID, time.Time, error) {
	filename16, err := syscall.UTF16PtrFromString(filename)
	if err != nil {
		return FileID{}, time.Time{}, err
	}
	h, err := syscall.CreateFile(filename16, 0, 0, nil, syscall.OPEN_EXISTING, uint32(syscall.FILE_FLAG_BACKUP_SEMANTICS), 0)
	if err != nil {
		return FileID{}, time.Time{}, err
	}
	defer syscall.CloseHandle(h)
	var i syscall.ByHandleFileInformation
	if err := syscall.GetFileInformationByHandle(h, &i); err != nil {
		return FileID{}, time.Time{}, err
	}
	mtime := time.Unix(0, i.LastWriteTime.Nanoseconds())
	return FileID{
		device: uint64(i.VolumeSerialNumber),
		inode:  uint64(i.FileIndexHigh)<<32 | uint64(i.FileIndexLow),
	}, mtime, nil
}


================================================
FILE: internal/stdlib/deps.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package stdlib

type pkginfo struct {
	name string
	deps string // list of indices of dependencies, as varint-encoded deltas
}

var deps = [...]pkginfo{
	{"archive/tar", "\x03q\x03F=\x01\n\x01$\x01\x01\x02\x05\b\x02\x01\x02\x02\r"},
	{"archive/zip", "\x02\x04g\a\x03\x13\x021=\x01+\x05\x01\x0f\x03\x02\x0f\x04"},
	{"bufio", "\x03q\x86\x01D\x15"},
	{"bytes", "t+[\x03\fH\x02\x02"},
	{"cmp", ""},
	{"compress/bzip2", "\x02\x02\xf6\x01A"},
	{"compress/flate", "\x02r\x03\x83\x01\f\x033\x01\x03"},
	{"compress/gzip", "\x02\x04g\a\x03\x15nU"},
	{"compress/lzw", "\x02r\x03\x83\x01"},
	{"compress/zlib", "\x02\x04g\a\x03\x13\x01o"},
	{"container/heap", "\xbc\x02"},
	{"container/list", ""},
	{"container/ring", ""},
	{"context", "t\\p\x01\x0e"},
	{"crypto", "\x8a\x01pC"},
	{"crypto/aes", "\x10\v\t\x99\x02"},
	{"crypto/cipher", "\x03!\x01\x01 \x12\x1c,Z"},
	{"crypto/des", "\x10\x16 .,\x9d\x01\x03"},
	{"crypto/dsa", "F\x03+\x86\x01\r"},
	{"crypto/ecdh", "\x03\v\r\x10\x04\x17\x03\x0f\x1c\x86\x01"},
	{"crypto/ecdsa", "\x0e\x05\x03\x05\x01\x10\b\v\x06\x01\x03\x0e\x01\x1c\x86\x01\r\x05L\x01"},
	{"crypto/ed25519", "\x0e\x1f\x12\a\x03\b\a\x1cI=C"},
	{"crypto/elliptic", "4@\x86\x01\r9"},
	{"crypto/fips140", "#\x05\x95\x01\x98\x01"},
	{"crypto/hkdf", "0\x15\x01.\x16"},
	{"crypto/hmac", "\x1b\x16\x14\x01\x122"},
	{"crypto/hpke", "\x03\v\x02\x03\x04\x01\f\x01\x05\x1f\x05\a\x01\x01\x1d\x03\x13\x16\x9b\x01\x1c"},
	{"crypto/internal/boring", "\x0e\x02\x0el"},
	{"crypto/internal/boring/bbig", "\x1b\xec\x01N"},
	{"crypto/internal/boring/bcache", "\xc1\x02\x14"},
	{"crypto/internal/boring/sig", ""},
	{"crypto/internal/constanttime", ""},
	{"crypto/internal/cryptotest", "\x03\r\v\b%\x10\x19\x06\x13\x12 \x04\x06\t\x19\x01\x11\x11\x1b\x01\a\x05\b\x03\x05\f"},
	{"crypto/internal/entropy", "K"},
	{"crypto/internal/entropy/v1.0.0", "D0\x95\x018\x14"},
	{"crypto/internal/fips140", "C1\xbf\x01\v\x17"},
	{"crypto/internal/fips140/aes", "\x03 \x03\x02\x14\x05\x01\x01\x05,\x95\x014"},
	{"crypto/internal/fips140/aes/gcm", "#\x01\x02\x02\x02\x12\x05\x01\x06,\x92\x01"},
	{"crypto/internal/fips140/alias", "\xd5\x02"},
	{"crypto/internal/fips140/bigmod", "(\x19\x01\x06,\x95\x01"},
	{"crypto/internal/fips140/check", "#\x0e\a\t\x02\xb7\x01["},
	{"crypto/internal/fips140/check/checktest", "(\x8b\x02\""},
	{"crypto/internal/fips140/drbg", "\x03\x1f\x01\x01\x04\x14\x05\n)\x86\x01\x0f7\x01"},
	{"crypto/internal/fips140/ecdh", "\x03 \x05\x02\n\r3\x86\x01\x0f7"},
	{"crypto/internal/fips140/ecdsa", "\x03 \x04\x01\x02\a\x03\x06:\x16pF"},
	{"crypto/internal/fips140/ed25519", "\x03 \x05\x02\x04\f:\xc9\x01\x03"},
	{"crypto/internal/fips140/edwards25519", "\x1f\t\a\x123\x95\x017"},
	{"crypto/internal/fips140/edwards25519/field", "(\x14\x053\x95\x01"},
	{"crypto/internal/fips140/hkdf", "\x03 \x05\t\a<\x16"},
	{"crypto/internal/fips140/hmac", "\x03 \x15\x01\x01:\x16"},
	{"crypto/internal/fips140/mldsa", "\x03\x1c\x04\x05\x02\x0e\x01\x03\x053\x95\x017"},
	{"crypto/internal/fips140/mlkem", "\x03 \x05\x02\x0f\x03\x053\xcc\x01"},
	{"crypto/internal/fips140/nistec", "\x1f\t\r\f3\x95\x01*\r\x15"},
	{"crypto/internal/fips140/nistec/fiat", "(\x148\x95\x01"},
	{"crypto/internal/fips140/pbkdf2", "\x03 \x05\t\a<\x16"},
	{"crypto/internal/fips140/rsa", "\x03\x1c\x04\x04\x01\x02\x0e\x01\x01\x028\x16pF"},
	{"crypto/internal/fips140/sha256", "\x03 \x1e\x01\x06,\x16\x7f"},
	{"crypto/internal/fips140/sha3", "\x03 \x19\x05\x012\x95\x01L"},
	{"crypto/internal/fips140/sha512", "\x03 \x1e\x01\x06,\x16\x7f"},
	{"crypto/internal/fips140/ssh", "(b"},
	{"crypto/internal/fips140/subtle", "\x1f\a\x1b\xc8\x01"},
	{"crypto/internal/fips140/tls12", "\x03 \x05\t\a\x02:\x16"},
	{"crypto/internal/fips140/tls13", "\x03 \x05\b\b\t3\x16"},
	{"crypto/internal/fips140cache", "\xb3\x02\r'"},
	{"crypto/internal/fips140deps", ""},
	{"crypto/internal/fips140deps/byteorder", "\xa0\x01"},
	{"crypto/internal/fips140deps/cpu", "\xb5\x01\a"},
	{"crypto/internal/fips140deps/godebug", "\xbd\x01"},
	{"crypto/internal/fips140deps/time", "\xcf\x02"},
	{"crypto/internal/fips140hash", "9\x1d4\xcb\x01"},
	{"crypto/internal/fips140only", "\x17\x13\x0e\x01\x01Pp"},
	{"crypto/internal/fips140test", ""},
	{"crypto/internal/impl", "\xbe\x02"},
	{"crypto/internal/rand", "\x1b\x0f s=["},
	{"crypto/internal/randutil", "\xfa\x01\x12"},
	{"crypto/internal/sysrand", "tq! \r\r\x01\x01\r\x06"},
	{"crypto/internal/sysrand/internal/seccomp", "t"},
	{"crypto/md5", "\x0e8.\x16\x16i"},
	{"crypto/mlkem", "\x0e%"},
	{"crypto/mlkem/mlkemtest", "3\x13\b&"},
	{"crypto/pbkdf2", "6\x0f\x01.\x16"},
	{"crypto/rand", "\x1b\x0f\x1c\x03+\x86\x01\rN"},
	{"crypto/rc4", "& .\xc9\x01"},
	{"crypto/rsa", "\x0e\r\x01\v\x10\x0e\x01\x03\b\a\x1c\x03\x133=\f\x01"},
	{"crypto/sha1", "\x0e\r+\x02,\x16\x16\x15T"},
	{"crypto/sha256", "\x0e\r\x1dR"},
	{"crypto/sha3", "\x0e+Q\xcb\x01"},
	{"crypto/sha512", "\x0e\r\x1fP"},
	{"crypto/subtle", "\x1f\x1d\x9f\x01z"},
	{"crypto/tls", "\x03\b\x02\x01\x01\x01\x01\x02\x01\x01\x01\x02\x01\x01\x01\t\x01\x18\x01\x0f\x01\x03\x01\x01\x01\x01\x02\x01\x02\x01\x17\x02\x03\x13\x16\x15\b=\x16\x16\r\b\x01\x01\x01\x02\x01\x0e\x06\x02\x01\x0f"},
	{"crypto/tls/internal/fips140tls", "\x17\xaa\x02"},
	{"crypto/x509", "\x03\v\x01\x01\x01\x01\x01\x01\x01\x017\x06\x01\x01\x02\x05\x0e\x06\x02\x02\x03F\x03:\x01\x02\b\x01\x01\x02\a\x10\x05\x01\x06\a\b\x02\x01\x02\x0f\x02\x01\x01\x02\x03\x01"},
	{"crypto/x509/pkix", "j\x06\a\x90\x01H"},
	{"database/sql", "\x03\nQ\x16\x03\x83\x01\v\a\"\x05\b\x02\x03\x01\x0e\x02\x02\x02"},
	{"database/sql/driver", "\rg\x03\xb7\x01\x0f\x12"},
	{"debug/buildinfo", "\x03^\x02\x01\x01\b\a\x03g\x1a\x02\x01+\x0f "},
	{"debug/dwarf", "\x03j\a\x03\x83\x011\x11\x01\x01"},
	{"debug/elf", "\x03\x06W\r\a\x03g\x1b\x01\f \x17\x01\x17"},
	{"debug/gosym", "\x03j\n$\xa1\x01\x01\x01\x02"},
	{"debug/macho", "\x03\x06W\r\ng\x1c,\x17\x01"},
	{"debug/pe", "\x03\x06W\r\a\x03g\x1c,\x17\x01\x17"},
	{"debug/plan9obj", "m\a\x03g\x1c,"},
	{"embed", "t+B\x19\x01T"},
	{"embed/internal/embedtest", ""},
	{"encoding", ""},
	{"encoding/ascii85", "\xfa\x01C"},
	{"encoding/asn1", "\x03q\x03g(\x01'\r\x02\x01\x11\x03\x01"},
	{"encoding/base32", "\xfa\x01A\x02"},
	{"encoding/base64", "\xa0\x01ZA\x02"},
	{"encoding/binary", "t\x86\x01\f(\r\x05"},
	{"encoding/csv", "\x02\x01q\x03\x83\x01D\x13\x02"},
	{"encoding/gob", "\x02f\x05\a\x03g\x1c\v\x01\x03\x1d\b\x12\x01\x10\x02"},
	{"encoding/hex", "t\x03\x83\x01A\x03"},
	{"encoding/json", "\x03\x01d\x04\b\x03\x83\x01\f(\r\x02\x01\x02\x11\x01\x01\x02"},
	{"encoding/pem", "\x03i\b\x86\x01A\x03"},
	{"encoding/xml", "\x02\x01e\f\x03\x83\x014\x05\n\x01\x02\x11\x02"},
	{"errors", "\xd0\x01\x85\x01"},
	{"expvar", "qLA\b\v\x15\r\b\x02\x03\x01\x12"},
	{"flag", "h\f\x03\x83\x01,\b\x05\b\x02\x01\x11"},
	{"fmt", "tF'\x19\f \b\r\x02\x03\x13"},
	{"go/ast", "\x03\x01s\x0f\x01s\x03)\b\r\x02\x01\x13\x02"},
	{"go/build", "\x02\x01q\x03\x01\x02\x02\b\x02\x01\x17\x1f\x04\x02\b\x1c\x13\x01+\x01\x04\x01\a\b\x02\x01\x13\x02\x02"},
	{"go/build/constraint", "t\xc9\x01\x01\x13\x02"},
	{"go/constant", "w\x10\x7f\x01\x024\x01\x02\x13"},
	{"go/doc", "\x04s\x01\x05\n=61\x10\x02\x01\x13\x02"},
	{"go/doc/comment", "\x03t\xc4\x01\x01\x01\x01\x13\x02"},
	{"go/format", "\x03t\x01\f\x01\x02sD"},
	{"go/importer", "y\a\x01\x02\x04\x01r9"},
	{"go/internal/gccgoimporter", "\x02\x01^\x13\x03\x04\f\x01p\x02,\x01\x05\x11\x01\r\b"},
	{"go/internal/gcimporter", "\x02u\x10\x010\x05\r0,\x15\x03\x02"},
	{"go/internal/scannerhooks", "\x87\x01"},
	{"go/internal/srcimporter", "w\x01\x01\v\x03\x01r,\x01\x05\x12\x02\x15"},
	{"go/parser", "\x03q\x03\x01\x02\b\x04\x01s\x01+\x06\x12"},
	{"go/printer", "w\x01\x02\x03\ns\f \x15\x02\x01\x02\f\x05\x02"},
	{"go/scanner", "\x03t\v\x05s2\x10\x01\x14\x02"},
	{"go/token", "\x04s\x86\x01>\x02\x03\x01\x10\x02"},
	{"go/types", "\x03\x01\x06j\x03\x01\x03\t\x03\x024\x063\x04\x03\t \x06\a\b\x01\x01\x01\x02\x01\x10\x02\x02"},
	{"go/version", "\xc2\x01|"},
	{"hash", "\xfa\x01"},
	{"hash/adler32", "t\x16\x16"},
	{"hash/crc32", "t\x16\x16\x15\x8b\x01\x01\x14"},
	{"hash/crc64", "t\x16\x16\xa0\x01"},
	{"hash/fnv", "t\x16\x16i"},
	{"hash/maphash", "\x8a\x01\x11<~"},
	{"html", "\xbe\x02\x02\x13"},
	{"html/template", "\x03n\x06\x19-=\x01\n!\x05\x01\x02\x03\f\x01\x02\r\x01\x03\x02"},
	{"image", "\x02r\x1fg\x0f4\x03\x01"},
	{"image/color", ""},
	{"image/color/palette", "\x93\x01"},
	{"image/draw", "\x92\x01\x01\x04"},
	{"image/gif", "\x02\x01\x05l\x03\x1b\x01\x01\x01\vZ\x0f"},
	{"image/internal/imageutil", "\x92\x01"},
	{"image/jpeg", "\x02r\x1e\x01\x04c"},
	{"image/png", "\x02\ad\n\x13\x02\x06\x01gC"},
	{"index/suffixarray", "\x03j\a\x86\x01\f+\n\x01"},
	{"internal/abi", "\xbc\x01\x99\x01"},
	{"internal/asan", "\xd5\x02"},
	{"internal/bisect", "\xb3\x02\r\x01"},
	{"internal/buildcfg", "wHg\x06\x02\x05\n\x01"},
	{"internal/bytealg", "\xb5\x01\xa0\x01"},
	{"internal/byteorder", ""},
	{"internal/cfg", ""},
	{"internal/cgrouptest", "w[T\x06\x0f\x02\x01\x04\x01"},
	{"internal/chacha8rand", "\xa0\x01\x15\a\x99\x01"},
	{"internal/copyright", ""},
	{"internal/coverage", ""},
	{"internal/coverage/calloc", ""},
	{"internal/coverage/cfile", "q\x06\x17\x17\x01\x02\x01\x01\x01\x01\x01\x01\x01\"\x02',\x06\a\n\x01\x03\x0e\x06"},
	{"internal/coverage/cformat", "\x04s.\x04Q\v6\x01\x02\x0e"},
	{"internal/coverage/cmerge", "w.a"},
	{"internal/coverage/decodecounter", "m\n.\v\x02H,\x17\x18"},
	{"internal/coverage/decodemeta", "\x02k\n\x17\x17\v\x02H,"},
	{"internal/coverage/encodecounter", "\x02k\n.\f\x01\x02F\v!\x15"},
	{"internal/coverage/encodemeta", "\x02\x01j\n\x13\x04\x17\r\x02F,/"},
	{"internal/coverage/pods", "\x04s.\x81\x01\x06\x05\n\x02\x01"},
	{"internal/coverage/rtcov", "\xd5\x02"},
	{"internal/coverage/slicereader", "m\n\x83\x01["},
	{"internal/coverage/slicewriter", "w\x83\x01"},
	{"internal/coverage/stringtab", "w9\x04F"},
	{"internal/coverage/test", ""},
	{"internal/coverage/uleb128", ""},
	{"internal/cpu", "\xd5\x02"},
	{"internal/dag", "\x04s\xc4\x01\x03"},
	{"internal/diff", "\x03t\xc5\x01\x02"},
	{"internal/exportdata", "\x02\x01q\x03\x02e\x1c,\x01\x05\x11\x01\x02"},
	{"internal/filepathlite", "t+B\x1a@"},
	{"internal/fmtsort", "\x04\xaa\x02\r"},
	{"internal/fuzz", "\x03\nH\x18\x04\x03\x03\x01\f\x036=\f\x03\x1d\x01\x05\x02\x05\n\x01\x02\x01\x01\r\x04\x02"},
	{"internal/goarch", ""},
	{"internal/godebug", "\x9d\x01!\x82\x01\x01\x14"},
	{"internal/godebugs", ""},
	{"internal/goexperiment", ""},
	{"internal/goos", ""},
	{"internal/goroot", "\xa6\x02\x01\x05\x12\x02"},
	{"internal/gover", "\x04"},
	{"internal/goversion", ""},
	{"internal/lazyregexp", "\xa6\x02\v\r\x02"},
	{"internal/lazytemplate", "\xfa\x01,\x18\x02\r"},
	{"internal/msan", "\xd5\x02"},
	{"internal/nettrace", ""},
	{"internal/obscuretestdata", "l\x8e\x01,"},
	{"internal/oserror", "t"},
	{"internal/pkgbits", "\x03R\x18\a\x03\x04\fs\r\x1f\r\n\x01"},
	{"internal/platform", ""},
	{"internal/poll", "tl\x05\x159\r\x01\x01\r\x06"},
	{"internal/profile", "\x03\x04m\x03\x83\x017\n\x01\x01\x01\x11"},
	{"internal/profilerecord", ""},
	{"internal/race", "\x9b\x01\xba\x01"},
	{"internal/reflectlite", "\x9b\x01!;<\""},
	{"internal/runtime/atomic", "\xbc\x01\x99\x01"},
	{"internal/runtime/cgroup", "\x9f\x01=\x04u"},
	{"internal/runtime/exithook", "\xd1\x01\x84\x01"},
	{"internal/runtime/gc", "\xbc\x01"},
	{"internal/runtime/gc/internal/gen", "\nc\n\x18k\x04\v\x1d\b\x10\x02"},
	{"internal/runtime/gc/scan", "\xb5\x01\a\x18\az"},
	{"internal/runtime/maps", "\x9b\x01\x01 \n\t\t\x03z"},
	{"internal/runtime/math", "\xbc\x01"},
	{"internal/runtime/pprof/label", ""},
	{"internal/runtime/startlinetest", ""},
	{"internal/runtime/sys", "\xbc\x01\x04"},
	{"internal/runtime/syscall/linux", "\xbc\x01\x99\x01"},
	{"internal/runtime/wasitest", ""},
	{"internal/saferio", "\xfa\x01["},
	{"internal/singleflight", "\xc0\x02"},
	{"internal/strconv", "\x89\x02L"},
	{"internal/stringslite", "\x9f\x01\xb6\x01"},
	{"internal/sync", "\x9b\x01!\x13r\x14"},
	{"internal/synctest", "\x9b\x01\xba\x01"},
	{"internal/syscall/execenv", "\xc2\x02"},
	{"internal/syscall/unix", "\xb3\x02\x0e\x01\x13"},
	{"internal/sysinfo", "\x02\x01\xb2\x01E,\x18\x02"},
	{"internal/syslist", ""},
	{"internal/testenv", "\x03\ng\x02\x01*\x1b\x0f0+\x01\x05\a\n\x01\x02\x02\x01\f"},
	{"internal/testhash", "\x03\x87\x01p\x118\f"},
	{"internal/testlog", "\xc0\x02\x01\x14"},
	{"internal/testpty", "t\x03\xaf\x01"},
	{"internal/trace", "\x02\x01\x01\x06c\a\x03w\x03\x03\x06\x03\t+\n\x01\x01\x01\x11\x06"},
	{"internal/trace/internal/testgen", "\x03j\nu\x03\x02\x03\x011\v\r\x11"},
	{"internal/trace/internal/tracev1", "\x03\x01i\a\x03}\x06\f5\x01"},
	{"internal/trace/raw", "\x02k\nz\x03\x06C\x01\x13"},
	{"internal/trace/testtrace", "\x02\x01q\x03q\x04\x03\x05\x01\x05,\v\x02\b\x02\x01\x05"},
	{"internal/trace/tracev2", ""},
	{"internal/trace/traceviewer", "\x02d\v\x06\x1a<\x1f\a\a\x04\b\v\x15\x01\x05\a\n\x01\x02\x0f"},
	{"internal/trace/traceviewer/format", ""},
	{"internal/trace/version", "wz\t"},
	{"internal/txtar", "\x03t\xaf\x01\x18"},
	{"internal/types/errors", "\xbd\x02"},
	{"internal/unsafeheader", "\xd5\x02"},
	{"internal/xcoff", "`\r\a\x03g\x1c,\x17\x01"},
	{"internal/zstd", "m\a\x03\x83\x01\x0f"},
	{"io", "t\xcc\x01"},
	{"io/fs", "t+*11\x10\x14\x04"},
	{"io/ioutil", "\xfa\x01\x01+\x15\x03"},
	{"iter", "\xcf\x01d\""},
	{"log", "w\x83\x01\x05'\r\r\x01\x0e"},
	{"log/internal", ""},
	{"log/slog", "\x03\n[\t\x03\x03\x83\x01\x04\x01\x02\x02\x03(\x05\b\x02\x01\x02\x01\x0e\x02\x02\x02"},
	{"log/slog/internal", ""},
	{"log/slog/internal/benchmarks", "\rg\x03\x83\x01\x06\x03:\x12"},
	{"log/slog/internal/buffer", "\xc0\x02"},
	{"log/syslog", "t\x03\x87\x01\x12\x16\x18\x02\x0f"},
	{"maps", "\xfd\x01X"},
	{"math", "\xb5\x01TL"},
	{"math/big", "\x03q\x03)\x15E\f\x03\x020\x02\x01\x02\x15"},
	{"math/big/internal/asmgen", "\x03\x01s\x92\x012\x03"},
	{"math/bits", "\xd5\x02"},
	{"math/cmplx", "\x86\x02\x03"},
	{"math/rand", "\xbd\x01I:\x01\x14"},
	{"math/rand/v2", "t,\x03c\x03L"},
	{"mime", "\x02\x01i\b\x03\x83\x01\v!\x15\x03\x02\x11\x02"},
	{"mime/multipart", "\x02\x01N#\x03F=\v\x01\a\x02\x15\x02\x06\x0f\x02\x01\x17"},
	{"mime/quotedprintable", "\x02\x01t\x83\x01"},
	{"net", "\x04\tg+\x1e\n\x05\x13\x01\x01\x04\x15\x01%\x06\r\b\x05\x01\x01\r\x06\a"},
	{"net/http", "\x02\x01\x03\x01\x04\x02D\b\x13\x01\a\x03F=\x01\x03\a\x01\x03\x02\x02\x01\x02\x06\x02\x01\x01\n\x01\x01\x05\x01\x02\x05\b\x01\x01\x01\x02\x01\x0e\x02\x02\x02\b\x01\x01\x01"},
	{"net/http/cgi", "\x02W\x1b\x03\x83\x01\x04\a\v\x01\x13\x01\x01\x01\x04\x01\x05\x02\b\x02\x01\x11\x0e"},
	{"net/http/cookiejar", "\x04p\x03\x99\x01\x01\b\a\x05\x16\x03\x02\x0f\x04"},
	{"net/http/fcgi", "\x02\x01\n`\a\x03\x83\x01\x16\x01\x01\x14\x18\x02\x0f"},
	{"net/http/httptest", "\x02\x01\nL\x02\x1b\x01\x83\x01\x04\x12\x01\n\t\x02\x17\x01\x02\x0f\x0e"},
	{"net/http/httptrace", "\rLnI\x14\n!"},
	{"net/http/httputil", "\x02\x01\ng\x03\x83\x01\x04\x0f\x03\x01\x05\x02\x01\v\x01\x19\x02\x01\x0e\x0e"},
	{"net/http/internal", "\x02\x01q\x03\x83\x01"},
	{"net/http/internal/ascii", "\xbe\x02\x13"},
	{"net/http/internal/httpcommon", "\rg\x03\x9f\x01\x0e\x01\x17\x01\x01\x02\x1d\x02"},
	{"net/http/internal/testcert", "\xbe\x02"},
	{"net/http/pprof", "\x02\x01\nj\x19-\x02\x0e-\x04\x13\x14\x01\r\x04\x03\x01\x02\x01\x11"},
	{"net/internal/cgotest", ""},
	{"net/internal/socktest", "w\xc9\x01\x02"},
	{"net/mail", "\x02r\x03\x83\x01\x04\x0f\x03\x14\x1a\x02\x0f\x04"},
	{"net/netip", "\x04p+\x01f\x034\x17"},
	{"net/rpc", "\x02m\x05\x03\x10\ni\x04\x12\x01\x1d\r\x03\x02"},
	{"net/rpc/jsonrpc", "q\x03\x03\x83\x01\x16\x11\x1f"},
	{"net/smtp", "\x194\f\x13\b\x03\x83\x01\x16\x14\x1a"},
	{"net/textproto", "\x02\x01q\x03\x83\x01\f\n-\x01\x02\x15"},
	{"net/url", "t\x03Fc\v\x10\x02\x01\x17"},
	{"os", "t+\x01\x19\x03\x10\x14\x01\x03\x01\x05\x10\x018\b\x05\x01\x01\r\x06"},
	{"os/exec", "\x03\ngI'\x01\x15\x01+\x06\a\n\x01\x03\x01\r"},
	{"os/exec/internal/fdtest", "\xc2\x02"},
	{"os/signal", "\r\x99\x02\x15\x05\x02"},
	{"os/user", "\x02\x01q\x03\x83\x01,\r\n\x01\x02"},
	{"path", "t+\xb4\x01"},
	{"path/filepath", "t+\x1aB+\r\b\x03\x04\x11"},
	{"plugin", "t"},
	{"reflect", "t'\x04\x1d\x13\b\x04\x05\x17\x06\t-\n\x03\x11\x02\x02"},
	{"reflect/internal/example1", ""},
	{"reflect/internal/example2", ""},
	{"regexp", "\x03\xf7\x018\t\x02\x01\x02\x11\x02"},
	{"regexp/syntax", "\xbb\x02\x01\x01\x01\x02\x11\x02"},
	{"runtime", "\x9b\x01\x04\x01\x03\f\x06\a\x02\x01\x01\x0e\x03\x01\x01\x01\x02\x01\x01\x01\x02\x01\x04\x01\x10\x18L"},
	{"runtime/coverage", "\xa7\x01S"},
	{"runtime/debug", "wUZ\r\b\x02\x01\x11\x06"},
	{"runtime/metrics", "\xbe\x01H-\""},
	{"runtime/pprof", "\x02\x01\x01\x03\x06`\a\x03$$\x0f\v!\f \r\b\x01\x01\x01\x02\x02\n\x03\x06"},
	{"runtime/race", "\xb9\x02"},
	{"runtime/race/internal/amd64v1", ""},
	{"runtime/trace", "\rg\x03z\t9\b\x05\x01\x0e\x06"},
	{"slices", "\x04\xf9\x01\fL"},
	{"sort", "\xd0\x0192"},
	{"strconv", "t+A\x01r"},
	{"strings", "t'\x04B\x19\x03\f7\x11\x02\x02"},
	{"structs", ""},
	{"sync", "\xcf\x01\x13\x01P\x0e\x14"},
	{"sync/atomic", "\xd5\x02"},
	{"syscall", "t(\x03\x01\x1c\n\x03\x06\r\x04S\b\x05\x01\x14"},
	{"testing", "\x03\ng\x02\x01X\x17\x14\f\x05\x1b\x06\x02\x05\x02\x05\x01\x02\x01\x02\x01\x0e\x02\x04"},
	{"testing/cryptotest", "QOZ\x124\x03\x12"},
	{"testing/fstest", "t\x03\x83\x01\x01\n&\x10\x03\t\b"},
	{"testing/internal/testdeps", "\x02\v\xae\x01/\x10,\x03\x05\x03\x06\a\x02\x0f"},
	{"testing/iotest", "\x03q\x03\x83\x01\x04"},
	{"testing/quick", "v\x01\x8f\x01\x05#\x10\x11"},
	{"testing/slogtest", "\rg\x03\x89\x01.\x05\x10\f"},
	{"testing/synctest", "\xe3\x01`\x12"},
	{"text/scanner", "\x03t\x83\x01,+\x02"},
	{"text/tabwriter", "w\x83\x01Y"},
	{"text/template", "t\x03C@\x01\n \x01\x05\x01\x02\x05\v\x02\x0e\x03\x02"},
	{"text/template/parse", "\x03t\xbc\x01\n\x01\x13\x02"},
	{"time", "t+\x1e$(*\r\x02\x13"},
	{"time/tzdata", "t\xce\x01\x13"},
	{"unicode", ""},
	{"unicode/utf16", ""},
	{"unicode/utf8", ""},
	{"unique", "\x9b\x01!%\x01Q\r\x01\x14\x12"},
	{"unsafe", ""},
	{"vendor/golang.org/x/crypto/chacha20", "\x10]\a\x95\x01*'"},
	{"vendor/golang.org/x/crypto/chacha20poly1305", "\x10\aV\a\xe2\x01\x04\x01\a"},
	{"vendor/golang.org/x/crypto/cryptobyte", "j\n\x03\x90\x01'!\n"},
	{"vendor/golang.org/x/crypto/cryptobyte/asn1", ""},
	{"vendor/golang.org/x/crypto/internal/alias", "\xd5\x02"},
	{"vendor/golang.org/x/crypto/internal/poly1305", "X\x15\x9c\x01"},
	{"vendor/golang.org/x/net/dns/dnsmessage", "t\xc7\x01"},
	{"vendor/golang.org/x/net/http/httpguts", "\x90\x02\x14\x1a\x15\r"},
	{"vendor/golang.org/x/net/http/httpproxy", "t\x03\x99\x01\x10\x05\x01\x18\x15\r"},
	{"vendor/golang.org/x/net/http2/hpack", "\x03q\x03\x83\x01F"},
	{"vendor/golang.org/x/net/idna", "w\x8f\x018\x15\x10\x02\x01"},
	{"vendor/golang.org/x/net/nettest", "\x03j\a\x03\x83\x01\x11\x05\x16\x01\f\n\x01\x02\x02\x01\f"},
	{"vendor/golang.org/x/sys/cpu", "\xa6\x02\r\n\x01\x17"},
	{"vendor/golang.org/x/text/secure/bidirule", "t\xdf\x01\x11\x01"},
	{"vendor/golang.org/x/text/transform", "\x03q\x86\x01Y"},
	{"vendor/golang.org/x/text/unicode/bidi", "\x03\bl\x87\x01>\x17"},
	{"vendor/golang.org/x/text/unicode/norm", "m\n\x83\x01F\x13\x11"},
	{"weak", "\x9b\x01\x98\x01\""},
}

// bootstrap is the list of bootstrap packages extracted from cmd/dist.
var bootstrap = map[string]bool{
	"cmp":                                     true,
	"cmd/asm":                                 true,
	"cmd/asm/internal/arch":                   true,
	"cmd/asm/internal/asm":                    true,
	"cmd/asm/internal/flags":                  true,
	"cmd/asm/internal/lex":                    true,
	"cmd/cgo":                                 true,
	"cmd/compile":                             true,
	"cmd/compile/internal/abi":                true,
	"cmd/compile/internal/abt":                true,
	"cmd/compile/internal/amd64":              true,
	"cmd/compile/internal/arm":                true,
	"cmd/compile/internal/arm64":              true,
	"cmd/compile/internal/base":               true,
	"cmd/compile/internal/bitvec":             true,
	"cmd/compile/internal/bloop":              true,
	"cmd/compile/internal/compare":            true,
	"cmd/compile/internal/coverage":           true,
	"cmd/compile/internal/deadlocals":         true,
	"cmd/compile/internal/devirtualize":       true,
	"cmd/compile/internal/dwarfgen":           true,
	"cmd/compile/internal/escape":             true,
	"cmd/compile/internal/gc":                 true,
	"cmd/compile/internal/importer":           true,
	"cmd/compile/internal/inline":             true,
	"cmd/compile/internal/inline/inlheur":     true,
	"cmd/compile/internal/inline/interleaved": true,
	"cmd/compile/internal/ir":                 true,
	"cmd/compile/internal/liveness":           true,
	"cmd/compile/internal/logopt":             true,
	"cmd/compile/internal/loong64":            true,
	"cmd/compile/internal/loopvar":            true,
	"cmd/compile/internal/mips":               true,
	"cmd/compile/internal/mips64":             true,
	"cmd/compile/internal/noder":              true,
	"cmd/compile/internal/objw":               true,
	"cmd/compile/internal/pgoir":              true,
	"cmd/compile/internal/pkginit":            true,
	"cmd/compile/internal/ppc64":              true,
	"cmd/compile/internal/rangefunc":          true,
	"cmd/compile/internal/reflectdata":        true,
	"cmd/compile/internal/riscv64":            true,
	"cmd/compile/internal/rttype":             true,
	"cmd/compile/internal/s390x":              true,
	"cmd/compile/internal/slice":              true,
	"cmd/compile/internal/ssa":                true,
	"cmd/compile/internal/ssagen":             true,
	"cmd/compile/internal/staticdata":         true,
	"cmd/compile/internal/staticinit":         true,
	"cmd/compile/internal/syntax":             true,
	"cmd/compile/internal/test":               true,
	"cmd/compile/internal/typebits":           true,
	"cmd/compile/internal/typecheck":          true,
	"cmd/compile/internal/types":              true,
	"cmd/compile/internal/types2":             true,
	"cmd/compile/internal/walk":               true,
	"cmd/compile/internal/wasm":               true,
	"cmd/compile/internal/x86":                true,
	"cmd/internal/archive":                    true,
	"cmd/internal/bio":                        true,
	"cmd/internal/codesign":                   true,
	"cmd/internal/dwarf":                      true,
	"cmd/internal/edit":                       true,
	"cmd/internal/gcprog":                     true,
	"cmd/internal/goobj":                      true,
	"cmd/internal/hash":                       true,
	"cmd/internal/macho":                      true,
	"cmd/internal/obj":                        true,
	"cmd/internal/obj/arm":                    true,
	"cmd/internal/obj/arm64":                  true,
	"cmd/internal/obj/loong64":                true,
	"cmd/internal/obj/mips":                   true,
	"cmd/internal/obj/ppc64":                  true,
	"cmd/internal/obj/riscv":                  true,
	"cmd/internal/obj/s390x":                  true,
	"cmd/internal/obj/wasm":                   true,
	"cmd/internal/obj/x86":                    true,
	"cmd/internal/objabi":                     true,
	"cmd/internal/par":                        true,
	"cmd/internal/pgo":                        true,
	"cmd/internal/pkgpath":                    true,
	"cmd/internal/quoted":                     true,
	"cmd/internal/src":                        true,
	"cmd/internal/sys":                        true,
	"cmd/internal/telemetry":                  true,
	"cmd/internal/telemetry/counter":          true,
	"cmd/link":                                true,
	"cmd/link/internal/amd64":                 true,
	"cmd/link/internal/arm":                   true,
	"cmd/link/internal/arm64":                 true,
	"cmd/link/internal/benchmark":             true,
	"cmd/link/internal/dwtest":                true,
	"cmd/link/internal/ld":                    true,
	"cmd/link/internal/loadelf":               true,
	"cmd/link/internal/loader":                true,
	"cmd/link/internal/loadmacho":             true,
	"cmd/link/internal/loadpe":                true,
	"cmd/link/internal/loadxcoff":             true,
	"cmd/link/internal/loong64":               true,
	"cmd/link/internal/mips":                  true,
	"cmd/link/internal/mips64":                true,
	"cmd/link/internal/ppc64":                 true,
	"cmd/link/internal/riscv64":               true,
	"cmd/link/internal/s390x":                 true,
	"cmd/link/internal/sym":                   true,
	"cmd/link/internal/wasm":                  true,
	"cmd/link/internal/x86":                   true,
	"compress/flate":                          true,
	"compress/zlib":                           true,
	"container/heap":                          true,
	"debug/dwarf":                             true,
	"debug/elf":                               true,
	"debug/macho":                             true,
	"debug/pe":                                true,
	"go/build/constraint":                     true,
	"go/constant":                             true,
	"go/version":                              true,
	"internal/abi":                            true,
	"internal/coverage":                       true,
	"cmd/internal/cov/covcmd":                 true,
	"internal/bisect":                         true,
	"internal/buildcfg":                       true,
	"internal/exportdata":                     true,
	"internal/goarch":                         true,
	"internal/godebugs":                       true,
	"internal/goexperiment":                   true,
	"internal/goroot":                         true,
	"internal/gover":                          true,
	"internal/goversion":                      true,
	"internal/lazyregexp":                     true,
	"internal/pkgbits":                        true,
	"internal/platform":                       true,
	"internal/profile":                        true,
	"internal/race":                           true,
	"internal/runtime/gc":                     true,
	"internal/saferio":                        true,
	"internal/syscall/unix":                   true,
	"internal/types/errors":                   true,
	"internal/unsafeheader":                   true,
	"internal/xcoff":                          true,
	"internal/zstd":                           true,
	"math/bits":                               true,
	"sort":                                    true,
}

// BootstrapVersion is the minor version of Go used during toolchain
// bootstrapping. Packages for which [IsBootstrapPackage] must not use
// features of Go newer than this version.
const BootstrapVersion = Version(24) // go1.24.6


================================================
FILE: internal/stdlib/deps_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stdlib_test

import (
	"iter"
	"os"
	"slices"
	"sort"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/internal/stdlib"
)

func TestImports(t *testing.T) { testDepsFunc(t, "testdata/nethttp.imports", stdlib.Imports) }
func TestDeps(t *testing.T)    { testDepsFunc(t, "testdata/nethttp.deps", stdlib.Dependencies) }

// testDepsFunc checks that the specified dependency function applied
// to net/http returns the set of dependencies in the named file.
func testDepsFunc(t *testing.T, filename string, depsFunc func(pkgs ...string) iter.Seq[string]) {
	data, err := os.ReadFile(filename)
	if err != nil {
		t.Fatal(err)
	}
	want := strings.Split(strings.TrimSpace(string(data)), "\n")
	got := slices.Collect(depsFunc("net/http"))
	sort.Strings(want)
	sort.Strings(got)
	if diff := cmp.Diff(got, want); diff != "" {
		t.Fatalf("Deps mismatch (-want +got):\n%s", diff)
	}
}

func TestIsBootstrapPackage(t *testing.T) {
	for pkg, want := range map[string]bool{
		"cmd/internal/obj/arm64":             true,
		"sort":                               true,
		"encoding/json":                      false,
		"golang.org/x/tools/internal/stdlib": false,
		"":                                   false,
	} {
		got := stdlib.IsBootstrapPackage(pkg)
		if got != want {
			t.Errorf("IsBootstrapPackage(%q) = %t", pkg, got)
		}
	}

	if stdlib.BootstrapVersion < 24 {
		t.Errorf("BootstrapVersion = %v, want at least go1.24", stdlib.BootstrapVersion)
	}
}


================================================
FILE: internal/stdlib/generate.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// The generate command reads all the GOROOT/api/go1.*.txt files and
// generates a single combined manifest.go file containing the Go
// standard library API symbols along with versions.
//
// It also runs "go list -deps std" and records the import graph. This
// information may be used, for example, to ensure that tools don't
// suggest fixes that import package P when analyzing one of P's
// dependencies.
package main

import (
	"bytes"
	"cmp"
	"encoding/binary"
	"encoding/json"
	"errors"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"io/fs"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"slices"
	"strconv"
	"strings"

	"golang.org/x/tools/go/packages"
)

func main() {
	log.SetFlags(log.Lshortfile) // to identify the source of the log messages

	dir := apidir()
	manifest(dir)
	deps()
}

// -- generate std manifest --

func manifest(apidir string) {
	// find the signatures
	cfg := packages.Config{
		Mode: packages.LoadTypes,
		Env:  append(os.Environ(), "CGO_ENABLED=0", "GOOS=linux", "GOARCH=amd64"),
	}
	// find the source. This is not totally reliable: different
	// systems may get different versions of unreleased APIs.
	// The result depends on the toolchain.
	// The x/tools release process regenerates the table
	// with the canonical toolchain.
	stdpkgs, err := packages.Load(&cfg, "std")
	if err != nil {
		log.Fatal(err)
	}
	signatures := make(map[string]map[string]string) // PkgPath->FuncName->signature
	// signatures start with func and may contain type parameters
	// "func[T comparable](value T) unique.Handle[T]"
	for _, pkg := range stdpkgs {
		if strings.HasPrefix(pkg.PkgPath, "vendor/") ||
			strings.HasPrefix(pkg.PkgPath, "internal/") ||
			strings.Contains(pkg.PkgPath, "/internal/") {
			continue
		}
		for _, name := range pkg.Types.Scope().Names() {
			fixer := func(p *types.Package) string {
				// fn.Signature() would have produced
				// "func(fi io/fs.FileInfo, link string) (*archive/tar.Header, error)"},
				// This produces
				// "func FileInfoHeader(fi fs.FileInfo, link string) (*Header, error)""
				// Note that the function name is superfluous, so it is removed below
				if p != pkg.Types {
					return p.Name()
				}
				return ""
			}
			obj := pkg.Types.Scope().Lookup(name)
			if fn, ok := obj.(*types.Func); ok {
				mp, ok := signatures[pkg.PkgPath]
				if !ok {
					mp = make(map[string]string)
					signatures[pkg.PkgPath] = mp
				}
				sig := types.ObjectString(fn, fixer)
				// remove the space and function name introduced by fixer
				sig = strings.Replace(sig, " "+name, "", 1)
				mp[name] = sig
			}
		}
	}

	// read the api data
	pkgs := make(map[string]map[string]symInfo) // package -> symbol -> info
	symRE := regexp.MustCompile(`^pkg (\S+).*?, (var|func|type|const|method \([^)]*\)) ([\pL\p{Nd}_]+)(.*)`)

	// parse parses symbols out of GOROOT/api/*.txt data, with the specified minor version.
	// Errors are reported against filename.
	parse := func(filename string, data []byte, minor int) {
		for linenum, line := range strings.Split(string(data), "\n") {
			if line == "" || strings.HasPrefix(line, "#") {
				continue
			}
			m := symRE.FindStringSubmatch(line)
			if m == nil {
				log.Fatalf("invalid input: %s:%d: %s", filename, linenum+1, line)
			}
			path, kind, sym, rest := m[1], m[2], m[3], m[4]

			if _, recv, ok := strings.Cut(kind, "method "); ok {
				// e.g. "method (*Func) Pos() token.Pos"
				kind = "method" // (concrete)

				recv := removeTypeParam(recv) // (*Foo[T]) -> (*Foo)

				sym = recv + "." + sym // (*T).m

			} else if method, ok := strings.CutPrefix(rest, " interface, "); ok && kind == "type" {
				// e.g. "pkg reflect, type Type interface, Comparable() bool"
				// or   "pkg net, type Error interface, Temporary //deprecated"

				kind = "method" // (abstract)

				if strings.HasPrefix(method, "unexported methods") {
					continue
				}
				if strings.Contains(method, " //deprecated") {
					continue
				}
				name, _, ok := strings.Cut(method, "(")
				if !ok {
					log.Printf("unexpected: %s", line)
					continue
				}
				sym = fmt.Sprintf("(%s).%s", sym, name) // (T).m

			} else if field, ok := strings.CutPrefix(rest, " struct, "); ok && kind == "type" {
				// e.g. "type ParenExpr struct, Lparen token.Pos"
				kind = "field"
				name, typ, _ := strings.Cut(field, " ")

				// The api script uses the name
				// "embedded" (ambiguously) for
				// the name of an anonymous field.
				if name == "embedded" {
					// Strip "*pkg.T" down to "T".
					typ = strings.TrimPrefix(typ, "*")
					if _, after, ok := strings.Cut(typ, "."); ok {
						typ = after
					}
					typ = removeTypeParam(typ) // embedded Foo[T] -> Foo
					name = typ
				}

				sym += "." + name // T.f
			}

			symbols, ok := pkgs[path]
			if !ok {
				symbols = make(map[string]symInfo)
				pkgs[path] = symbols
			}

			// Don't overwrite earlier entries:
			// enums are redeclared in later versions
			// as their encoding changes;
			// deprecations count as updates too.
			// TODO(adonovan): it would be better to mark
			// deprecated as a boolean without changing the
			// version.
			if _, ok := symbols[sym]; !ok {
				var sig string
				if kind == "func" {
					sig = signatures[path][sym]
				}
				symbols[sym] = symInfo{
					kind:      kind,
					minor:     minor,
					signature: sig,
				}
			}
		}
	}

	// Read and parse the GOROOT/api manifests.
	for minor := 0; ; minor++ {
		base := "go1.txt"
		if minor > 0 {
			base = fmt.Sprintf("go1.%d.txt", minor)
		}
		filename := filepath.Join(apidir, base)
		data, err := os.ReadFile(filename)
		if err != nil {
			if errors.Is(err, fs.ErrNotExist) {
				// All caught up.
				// Synthesize one final file from any api/next/*.txt fragments.
				// (They are consolidated into a go1.%d file some time between
				// the freeze and the first release candidate.)
				filenames, err := filepath.Glob(filepath.Join(apidir, "next", "*.txt"))
				if err != nil {
					log.Fatal(err)
				}
				var next bytes.Buffer
				for _, filename := range filenames {
					data, err := os.ReadFile(filename)
					if err != nil {
						log.Fatal(err)
					}
					next.Write(data)
				}
				parse(filename, next.Bytes(), minor) // (filename is a lie)
				break
			}
			log.Fatal(err)
		}
		parse(filename, data, minor)
	}

	// The APIs of the syscall/js and unsafe packages need to be computed explicitly,
	// because they're not included in the GOROOT/api/go1.*.txt files at this time.
	pkgs["syscall/js"] = loadSymbols("syscall/js", "GOOS=js", "GOARCH=wasm")
	pkgs["unsafe"] = exportedSymbols(types.Unsafe) // TODO(adonovan): set correct versions

	// Write the combined manifest.
	var buf bytes.Buffer
	buf.WriteString(`// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package stdlib

var PackageSymbols = map[string][]Symbol{
`)

	for _, path := range sortedKeys(pkgs) {
		pkg := pkgs[path]
		fmt.Fprintf(&buf, "\t%q: {\n", path)
		for _, name := range sortedKeys(pkg) {
			info := pkg[name]
			fmt.Fprintf(&buf, "\t\t{%q, %s, %d, %q},\n",
				name, strings.Title(info.kind), info.minor, info.signature)
		}
		fmt.Fprintln(&buf, "},")
	}
	fmt.Fprintln(&buf, "}")
	fmtbuf, err := format.Source(buf.Bytes())
	if err != nil {
		log.Fatal(err)
	}
	if err := os.WriteFile("manifest.go", fmtbuf, 0o666); err != nil {
		log.Fatal(err)
	}
}

// find the api directory, In most situations it is in GOROOT/api, but not always.
// TODO(pjw): understand where it might be, and if there could be newer and older versions
func apidir() string {
	stdout := new(bytes.Buffer)
	cmd := exec.Command("go", "env", "GOROOT", "GOPATH")
	cmd.Stdout = stdout
	cmd.Stderr = os.Stderr
	if err := cmd.Run(); err != nil {
		log.Fatal(err)
	}
	// Prefer GOROOT/api over GOPATH/api.
	for line := range strings.SplitSeq(stdout.String(), "\n") {
		apidir := filepath.Join(line, "api")
		info, err := os.Stat(apidir)
		if err == nil && info.IsDir() {
			return apidir
		}
	}
	log.Fatal("could not find api dir")
	return ""
}

type symInfo struct {
	kind  string // e.g. "func"
	minor int    // go1.%d
	// for completion snippets
	signature string // for Kind == stdlib.Func
}

// loadSymbols computes the exported symbols in the specified package
// by parsing and type-checking the current source.
func loadSymbols(pkg string, extraEnv ...string) map[string]symInfo {
	pkgs, err := packages.Load(&packages.Config{
		Mode: packages.NeedTypes,
		Env:  append(os.Environ(), extraEnv...),
	}, pkg)
	if err != nil {
		log.Fatalln(err)
	} else if len(pkgs) != 1 {
		log.Fatalf("got %d packages, want one package %q", len(pkgs), pkg)
	}
	return exportedSymbols(pkgs[0].Types)
}

func exportedSymbols(pkg *types.Package) map[string]symInfo {
	symbols := make(map[string]symInfo)
	for _, name := range pkg.Scope().Names() {
		if obj := pkg.Scope().Lookup(name); obj.Exported() {
			var kind string
			switch obj.(type) {
			case *types.Func, *types.Builtin:
				kind = "func"
			case *types.Const:
				kind = "const"
			case *types.Var:
				kind = "var"
			case *types.TypeName:
				kind = "type"
				// TODO(adonovan): expand fields and methods of syscall/js.*
			default:
				log.Fatalf("unexpected object type: %v", obj)
			}
			symbols[name] = symInfo{kind: kind, minor: 0} // pretend go1.0
		}
	}
	return symbols
}

func sortedKeys[M ~map[K]V, K cmp.Ordered, V any](m M) []K {
	r := make([]K, 0, len(m))
	for k := range m {
		r = append(r, k)
	}
	slices.Sort(r)
	return r
}

func removeTypeParam(s string) string {
	i := strings.IndexByte(s, '[')
	j := strings.LastIndexByte(s, ']')
	if i > 0 && j > i {
		s = s[:i] + s[j+len("["):]
	}
	return s
}

// -- generate dependency graph --

func deps() {
	type Package struct {
		// go list JSON output
		ImportPath string   // import path of package in dir
		Imports    []string // import paths used by this package

		// encoding
		index int
		deps  []int // indices of direct imports, sorted
	}
	pkgs := make(map[string]*Package)
	var keys []string
	for dec := json.NewDecoder(runGo("list", "-deps", "-json", "std")); dec.More(); {
		var pkg Package
		if err := dec.Decode(&pkg); err != nil {
			log.Fatal(err)
		}
		pkgs[pkg.ImportPath] = &pkg
		keys = append(keys, pkg.ImportPath)
	}

	// Sort and number the packages.
	// There are 344 as of Mar 2025.
	slices.Sort(keys)
	for i, name := range keys {
		pkgs[name].index = i
	}

	// Encode the dependencies.
	for _, pkg := range pkgs {
		for _, imp := range pkg.Imports {
			if imp == "C" {
				continue
			}
			pkg.deps = append(pkg.deps, pkgs[imp].index)
		}
		slices.Sort(pkg.deps)
	}

	// Emit the table.
	var buf bytes.Buffer
	buf.WriteString(`// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package stdlib

type pkginfo struct {
	name string
	deps string // list of indices of dependencies, as varint-encoded deltas
}
var deps = [...]pkginfo{
`)
	for _, name := range keys {
		prev := 0
		var deps []int
		for _, v := range pkgs[name].deps {
			deps = append(deps, v-prev) // delta
			prev = v
		}
		var data []byte
		for _, v := range deps {
			data = binary.AppendUvarint(data, uint64(v))
		}
		fmt.Fprintf(&buf, "\t{%q, %q},\n", name, data)
	}
	fmt.Fprintln(&buf, "}")

	// Also write the list of bootstrap packages.
	// (We can't use indices because it is not a subset of std.)
	bootstrap, version := bootstrap()
	minor := strings.Split(version, ".")[1] // "go1.2.3" -> "2"
	buf.WriteString(`
// bootstrap is the list of bootstrap packages extracted from cmd/dist.
var bootstrap = map[string]bool{
`)
	for _, pkg := range bootstrap {
		fmt.Fprintf(&buf, "\t%q: true,\n", pkg)
	}
	fmt.Fprintf(&buf, `}

// BootstrapVersion is the minor version of Go used during toolchain
// bootstrapping. Packages for which [IsBootstrapPackage] must not use
// features of Go newer than this version.
const BootstrapVersion = Version(%s) // %s
`, minor, version)

	// Format and update the dependencies file.
	fmtbuf, err := format.Source(buf.Bytes())
	if err != nil {
		log.Fatal(err)
	}
	if err := os.WriteFile("deps.go", fmtbuf, 0o666); err != nil {
		log.Fatal(err)
	}

	// Also generate the data for the test.
	for _, t := range [...]struct{ flag, filename string }{
		{"-deps=true", "testdata/nethttp.deps"},
		{`-f={{join .Imports "\n"}}`, "testdata/nethttp.imports"},
	} {
		stdout := new(bytes.Buffer)
		cmd := exec.Command("go", "list", t.flag, "net/http")
		cmd.Stdout = stdout
		cmd.Stderr = os.Stderr
		cmd.Env = append(os.Environ(), "CGO_ENABLED=0", "GOOS=linux", "GOARCH=amd64")
		if err := cmd.Run(); err != nil {
			log.Fatal(err)
		}
		if err := os.WriteFile(t.filename, stdout.Bytes(), 0666); err != nil {
			log.Fatal(err)
		}
	}
}

// bootstrap returns the list of bootstrap packages out of the
// source of the dist command, along with the minimum toolchain
// version.
//
// We assume it is "var bootstrapDirs []string" in buildtool.go, and
// is a list of string literals, either package names or "dir/...".
// TODO(adonovan): find a more robust solution.
func bootstrap() ([]string, string) {
	fset := token.NewFileSet()
	filename := strings.TrimSpace(runGo("list", "-f={{.Dir}}/buildtool.go", "cmd/dist").String())
	f, err := parser.ParseFile(fset, filename, nil, 0)
	if err != nil {
		log.Fatalf("can't parse buildtool.go file in cmd/dist package: %v", err)
	}

	const bootstrapVarName = "bootstrapDirs"
	var (
		args    = []string{"list"} // go list command to expand bootstrap packages
		version string
	)
	for _, decl := range f.Decls {
		decl, ok := decl.(*ast.GenDecl)
		if !ok {
			continue
		}
		for _, spec := range decl.Specs {
			spec, ok := spec.(*ast.ValueSpec)
			if !ok {
				continue
			}
			if len(spec.Names) != 1 {
				continue
			}
			switch spec.Names[0].Name {
			case bootstrapVarName:
				// var bootstrapDirs = []string{ ... }
				if len(spec.Values) != 1 {
					log.Fatalf("%s: %s var spec has %d values, want 1",
						fset.Position(spec.Pos()), len(spec.Values))
				}
				value0 := spec.Values[0]
				lit, ok := value0.(*ast.CompositeLit)
				if !ok {
					log.Fatalf("%s: %s assigned from %T, want slice literal",
						fset.Position(value0.Pos()), value0)
				}
				// Construct a go list command from the package patterns.
				for _, elt := range lit.Elts {
					lit, ok := elt.(*ast.BasicLit)
					if !ok {
						log.Fatalf("%s: element is %T, want string literal",
							fset.Position(elt.Pos()), elt)
					}
					pattern, err := strconv.Unquote(lit.Value)
					if err != nil {
						log.Fatalf("%s: %v", fset.Position(elt.Pos()), err)
					}
					args = append(args, pattern)
				}

			case "minBootstrap":
				// const minBootstrap = "go1.2.3"
				lit := spec.Values[0].(*ast.BasicLit)
				version, _ = strconv.Unquote(lit.Value)
			}
		}
	}
	if len(args) < 2 {
		log.Fatalf("can't find var %s in buildtool.go file in cmd/dist package: %v",
			bootstrapVarName, err)
	}
	if version == "" {
		log.Fatalf("can't find const minBootstrap version in buildtool.go file in cmd/dist package: %v",
			err)
	}

	return strings.Split(strings.TrimSpace(runGo(args...).String()), "\n"), version
}

func runGo(args ...string) *bytes.Buffer {
	cmd := exec.Command("go", args...)
	cmd.Env = append(os.Environ(), "CGO_ENABLED=0", "GOOS=linux", "GOARCH=amd64")
	stdout, err := cmd.Output()
	if err != nil {
		log.Fatalf("%s: failed: %v", cmd, err)
	}
	return bytes.NewBuffer(stdout)
}


================================================
FILE: internal/stdlib/import.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package stdlib

// This file provides the API for the import graph of the standard library.
//
// Be aware that the compiler-generated code for every package
// implicitly depends on package "runtime" and a handful of others
// (see runtimePkgs in GOROOT/src/cmd/internal/objabi/pkgspecial.go).

import (
	"encoding/binary"
	"iter"
	"slices"
	"strings"
)

// Imports returns the sequence of packages directly imported by the
// named standard packages, in name order.
// The imports of an unknown package are the empty set.
//
// The graph is built into the application and may differ from the
// graph in the Go source tree being analyzed by the application.
func Imports(pkgs ...string) iter.Seq[string] {
	return func(yield func(string) bool) {
		for _, pkg := range pkgs {
			if i, ok := find(pkg); ok {
				var depIndex uint64
				for data := []byte(deps[i].deps); len(data) > 0; {
					delta, n := binary.Uvarint(data)
					depIndex += delta
					if !yield(deps[depIndex].name) {
						return
					}
					data = data[n:]
				}
			}
		}
	}
}

// Dependencies returns the set of all dependencies of the named
// standard packages, including the initial package,
// in a deterministic topological order.
// The dependencies of an unknown package are the empty set.
//
// The graph is built into the application and may differ from the
// graph in the Go source tree being analyzed by the application.
func Dependencies(pkgs ...string) iter.Seq[string] {
	return func(yield func(string) bool) {
		for _, pkg := range pkgs {
			if i, ok := find(pkg); ok {
				var seen [1 + len(deps)/8]byte // bit set of seen packages
				var visit func(i int) bool
				visit = func(i int) bool {
					bit := byte(1) << (i % 8)
					if seen[i/8]&bit == 0 {
						seen[i/8] |= bit
						var depIndex uint64
						for data := []byte(deps[i].deps); len(data) > 0; {
							delta, n := binary.Uvarint(data)
							depIndex += delta
							if !visit(int(depIndex)) {
								return false
							}
							data = data[n:]
						}
						if !yield(deps[i].name) {
							return false
						}
					}
					return true
				}
				if !visit(i) {
					return
				}
			}
		}
	}
}

// find returns the index of pkg in the deps table.
func find(pkg string) (int, bool) {
	return slices.BinarySearchFunc(deps[:], pkg, func(p pkginfo, n string) int {
		return strings.Compare(p.name, n)
	})
}

// IsBootstrapPackage reports whether pkg is one of the low-level
// packages in the Go distribution that must compile with the older
// language version specified by [BootstrapVersion] during toolchain
// bootstrapping; see golang.org/s/go15bootstrap.
func IsBootstrapPackage(pkg string) bool {
	return bootstrap[pkg]
}


================================================
FILE: internal/stdlib/manifest.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by generate.go. DO NOT EDIT.

package stdlib

var PackageSymbols = map[string][]Symbol{
	"archive/tar": {
		{"(*Header).FileInfo", Method, 1, ""},
		{"(*Reader).Next", Method, 0, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Writer).AddFS", Method, 22, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"(*Writer).WriteHeader", Method, 0, ""},
		{"(FileInfoNames).Gname", Method, 23, ""},
		{"(FileInfoNames).IsDir", Method, 23, ""},
		{"(FileInfoNames).ModTime", Method, 23, ""},
		{"(FileInfoNames).Mode", Method, 23, ""},
		{"(FileInfoNames).Name", Method, 23, ""},
		{"(FileInfoNames).Size", Method, 23, ""},
		{"(FileInfoNames).Sys", Method, 23, ""},
		{"(FileInfoNames).Uname", Method, 23, ""},
		{"(Format).String", Method, 10, ""},
		{"ErrFieldTooLong", Var, 0, ""},
		{"ErrHeader", Var, 0, ""},
		{"ErrInsecurePath", Var, 20, ""},
		{"ErrWriteAfterClose", Var, 0, ""},
		{"ErrWriteTooLong", Var, 0, ""},
		{"FileInfoHeader", Func, 1, "func(fi fs.FileInfo, link string) (*Header, error)"},
		{"FileInfoNames", Type, 23, ""},
		{"Format", Type, 10, ""},
		{"FormatGNU", Const, 10, ""},
		{"FormatPAX", Const, 10, ""},
		{"FormatUSTAR", Const, 10, ""},
		{"FormatUnknown", Const, 10, ""},
		{"Header", Type, 0, ""},
		{"Header.AccessTime", Field, 0, ""},
		{"Header.ChangeTime", Field, 0, ""},
		{"Header.Devmajor", Field, 0, ""},
		{"Header.Devminor", Field, 0, ""},
		{"Header.Format", Field, 10, ""},
		{"Header.Gid", Field, 0, ""},
		{"Header.Gname", Field, 0, ""},
		{"Header.Linkname", Field, 0, ""},
		{"Header.ModTime", Field, 0, ""},
		{"Header.Mode", Field, 0, ""},
		{"Header.Name", Field, 0, ""},
		{"Header.PAXRecords", Field, 10, ""},
		{"Header.Size", Field, 0, ""},
		{"Header.Typeflag", Field, 0, ""},
		{"Header.Uid", Field, 0, ""},
		{"Header.Uname", Field, 0, ""},
		{"Header.Xattrs", Field, 3, ""},
		{"NewReader", Func, 0, "func(r io.Reader) *Reader"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"Reader", Type, 0, ""},
		{"TypeBlock", Const, 0, ""},
		{"TypeChar", Const, 0, ""},
		{"TypeCont", Const, 0, ""},
		{"TypeDir", Const, 0, ""},
		{"TypeFifo", Const, 0, ""},
		{"TypeGNULongLink", Const, 1, ""},
		{"TypeGNULongName", Const, 1, ""},
		{"TypeGNUSparse", Const, 3, ""},
		{"TypeLink", Const, 0, ""},
		{"TypeReg", Const, 0, ""},
		{"TypeRegA", Const, 0, ""},
		{"TypeSymlink", Const, 0, ""},
		{"TypeXGlobalHeader", Const, 0, ""},
		{"TypeXHeader", Const, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"archive/zip": {
		{"(*File).DataOffset", Method, 2, ""},
		{"(*File).FileInfo", Method, 0, ""},
		{"(*File).ModTime", Method, 0, ""},
		{"(*File).Mode", Method, 0, ""},
		{"(*File).Open", Method, 0, ""},
		{"(*File).OpenRaw", Method, 17, ""},
		{"(*File).SetModTime", Method, 0, ""},
		{"(*File).SetMode", Method, 0, ""},
		{"(*FileHeader).FileInfo", Method, 0, ""},
		{"(*FileHeader).ModTime", Method, 0, ""},
		{"(*FileHeader).Mode", Method, 0, ""},
		{"(*FileHeader).SetModTime", Method, 0, ""},
		{"(*FileHeader).SetMode", Method, 0, ""},
		{"(*ReadCloser).Close", Method, 0, ""},
		{"(*ReadCloser).Open", Method, 16, ""},
		{"(*ReadCloser).RegisterDecompressor", Method, 6, ""},
		{"(*Reader).Open", Method, 16, ""},
		{"(*Reader).RegisterDecompressor", Method, 6, ""},
		{"(*Writer).AddFS", Method, 22, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Copy", Method, 17, ""},
		{"(*Writer).Create", Method, 0, ""},
		{"(*Writer).CreateHeader", Method, 0, ""},
		{"(*Writer).CreateRaw", Method, 17, ""},
		{"(*Writer).Flush", Method, 4, ""},
		{"(*Writer).RegisterCompressor", Method, 6, ""},
		{"(*Writer).SetComment", Method, 10, ""},
		{"(*Writer).SetOffset", Method, 5, ""},
		{"Compressor", Type, 2, ""},
		{"Decompressor", Type, 2, ""},
		{"Deflate", Const, 0, ""},
		{"ErrAlgorithm", Var, 0, ""},
		{"ErrChecksum", Var, 0, ""},
		{"ErrFormat", Var, 0, ""},
		{"ErrInsecurePath", Var, 20, ""},
		{"File", Type, 0, ""},
		{"File.FileHeader", Field, 0, ""},
		{"FileHeader", Type, 0, ""},
		{"FileHeader.CRC32", Field, 0, ""},
		{"FileHeader.Comment", Field, 0, ""},
		{"FileHeader.CompressedSize", Field, 0, ""},
		{"FileHeader.CompressedSize64", Field, 1, ""},
		{"FileHeader.CreatorVersion", Field, 0, ""},
		{"FileHeader.ExternalAttrs", Field, 0, ""},
		{"FileHeader.Extra", Field, 0, ""},
		{"FileHeader.Flags", Field, 0, ""},
		{"FileHeader.Method", Field, 0, ""},
		{"FileHeader.Modified", Field, 10, ""},
		{"FileHeader.ModifiedDate", Field, 0, ""},
		{"FileHeader.ModifiedTime", Field, 0, ""},
		{"FileHeader.Name", Field, 0, ""},
		{"FileHeader.NonUTF8", Field, 10, ""},
		{"FileHeader.ReaderVersion", Field, 0, ""},
		{"FileHeader.UncompressedSize", Field, 0, ""},
		{"FileHeader.UncompressedSize64", Field, 1, ""},
		{"FileInfoHeader", Func, 0, "func(fi fs.FileInfo) (*FileHeader, error)"},
		{"NewReader", Func, 0, "func(r io.ReaderAt, size int64) (*Reader, error)"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"OpenReader", Func, 0, "func(name string) (*ReadCloser, error)"},
		{"ReadCloser", Type, 0, ""},
		{"ReadCloser.Reader", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"Reader.Comment", Field, 0, ""},
		{"Reader.File", Field, 0, ""},
		{"RegisterCompressor", Func, 2, "func(method uint16, comp Compressor)"},
		{"RegisterDecompressor", Func, 2, "func(method uint16, dcomp Decompressor)"},
		{"Store", Const, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"bufio": {
		{"(*Reader).Buffered", Method, 0, ""},
		{"(*Reader).Discard", Method, 5, ""},
		{"(*Reader).Peek", Method, 0, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Reader).ReadByte", Method, 0, ""},
		{"(*Reader).ReadBytes", Method, 0, ""},
		{"(*Reader).ReadLine", Method, 0, ""},
		{"(*Reader).ReadRune", Method, 0, ""},
		{"(*Reader).ReadSlice", Method, 0, ""},
		{"(*Reader).ReadString", Method, 0, ""},
		{"(*Reader).Reset", Method, 2, ""},
		{"(*Reader).Size", Method, 10, ""},
		{"(*Reader).UnreadByte", Method, 0, ""},
		{"(*Reader).UnreadRune", Method, 0, ""},
		{"(*Reader).WriteTo", Method, 1, ""},
		{"(*Scanner).Buffer", Method, 6, ""},
		{"(*Scanner).Bytes", Method, 1, ""},
		{"(*Scanner).Err", Method, 1, ""},
		{"(*Scanner).Scan", Method, 1, ""},
		{"(*Scanner).Split", Method, 1, ""},
		{"(*Scanner).Text", Method, 1, ""},
		{"(*Writer).Available", Method, 0, ""},
		{"(*Writer).AvailableBuffer", Method, 18, ""},
		{"(*Writer).Buffered", Method, 0, ""},
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).ReadFrom", Method, 1, ""},
		{"(*Writer).Reset", Method, 2, ""},
		{"(*Writer).Size", Method, 10, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"(*Writer).WriteByte", Method, 0, ""},
		{"(*Writer).WriteRune", Method, 0, ""},
		{"(*Writer).WriteString", Method, 0, ""},
		{"(ReadWriter).Available", Method, 0, ""},
		{"(ReadWriter).AvailableBuffer", Method, 18, ""},
		{"(ReadWriter).Discard", Method, 5, ""},
		{"(ReadWriter).Flush", Method, 0, ""},
		{"(ReadWriter).Peek", Method, 0, ""},
		{"(ReadWriter).Read", Method, 0, ""},
		{"(ReadWriter).ReadByte", Method, 0, ""},
		{"(ReadWriter).ReadBytes", Method, 0, ""},
		{"(ReadWriter).ReadFrom", Method, 1, ""},
		{"(ReadWriter).ReadLine", Method, 0, ""},
		{"(ReadWriter).ReadRune", Method, 0, ""},
		{"(ReadWriter).ReadSlice", Method, 0, ""},
		{"(ReadWriter).ReadString", Method, 0, ""},
		{"(ReadWriter).UnreadByte", Method, 0, ""},
		{"(ReadWriter).UnreadRune", Method, 0, ""},
		{"(ReadWriter).Write", Method, 0, ""},
		{"(ReadWriter).WriteByte", Method, 0, ""},
		{"(ReadWriter).WriteRune", Method, 0, ""},
		{"(ReadWriter).WriteString", Method, 0, ""},
		{"(ReadWriter).WriteTo", Method, 1, ""},
		{"ErrAdvanceTooFar", Var, 1, ""},
		{"ErrBadReadCount", Var, 15, ""},
		{"ErrBufferFull", Var, 0, ""},
		{"ErrFinalToken", Var, 6, ""},
		{"ErrInvalidUnreadByte", Var, 0, ""},
		{"ErrInvalidUnreadRune", Var, 0, ""},
		{"ErrNegativeAdvance", Var, 1, ""},
		{"ErrNegativeCount", Var, 0, ""},
		{"ErrTooLong", Var, 1, ""},
		{"MaxScanTokenSize", Const, 1, ""},
		{"NewReadWriter", Func, 0, "func(r *Reader, w *Writer) *ReadWriter"},
		{"NewReader", Func, 0, "func(rd io.Reader) *Reader"},
		{"NewReaderSize", Func, 0, "func(rd io.Reader, size int) *Reader"},
		{"NewScanner", Func, 1, "func(r io.Reader) *Scanner"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"NewWriterSize", Func, 0, "func(w io.Writer, size int) *Writer"},
		{"ReadWriter", Type, 0, ""},
		{"ReadWriter.Reader", Field, 0, ""},
		{"ReadWriter.Writer", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"ScanBytes", Func, 1, "func(data []byte, atEOF bool) (advance int, token []byte, err error)"},
		{"ScanLines", Func, 1, "func(data []byte, atEOF bool) (advance int, token []byte, err error)"},
		{"ScanRunes", Func, 1, "func(data []byte, atEOF bool) (advance int, token []byte, err error)"},
		{"ScanWords", Func, 1, "func(data []byte, atEOF bool) (advance int, token []byte, err error)"},
		{"Scanner", Type, 1, ""},
		{"SplitFunc", Type, 1, ""},
		{"Writer", Type, 0, ""},
	},
	"bytes": {
		{"(*Buffer).Available", Method, 21, ""},
		{"(*Buffer).AvailableBuffer", Method, 21, ""},
		{"(*Buffer).Bytes", Method, 0, ""},
		{"(*Buffer).Cap", Method, 5, ""},
		{"(*Buffer).Grow", Method, 1, ""},
		{"(*Buffer).Len", Method, 0, ""},
		{"(*Buffer).Next", Method, 0, ""},
		{"(*Buffer).Peek", Method, 26, ""},
		{"(*Buffer).Read", Method, 0, ""},
		{"(*Buffer).ReadByte", Method, 0, ""},
		{"(*Buffer).ReadBytes", Method, 0, ""},
		{"(*Buffer).ReadFrom", Method, 0, ""},
		{"(*Buffer).ReadRune", Method, 0, ""},
		{"(*Buffer).ReadString", Method, 0, ""},
		{"(*Buffer).Reset", Method, 0, ""},
		{"(*Buffer).String", Method, 0, ""},
		{"(*Buffer).Truncate", Method, 0, ""},
		{"(*Buffer).UnreadByte", Method, 0, ""},
		{"(*Buffer).UnreadRune", Method, 0, ""},
		{"(*Buffer).Write", Method, 0, ""},
		{"(*Buffer).WriteByte", Method, 0, ""},
		{"(*Buffer).WriteRune", Method, 0, ""},
		{"(*Buffer).WriteString", Method, 0, ""},
		{"(*Buffer).WriteTo", Method, 0, ""},
		{"(*Reader).Len", Method, 0, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Reader).ReadAt", Method, 0, ""},
		{"(*Reader).ReadByte", Method, 0, ""},
		{"(*Reader).ReadRune", Method, 0, ""},
		{"(*Reader).Reset", Method, 7, ""},
		{"(*Reader).Seek", Method, 0, ""},
		{"(*Reader).Size", Method, 5, ""},
		{"(*Reader).UnreadByte", Method, 0, ""},
		{"(*Reader).UnreadRune", Method, 0, ""},
		{"(*Reader).WriteTo", Method, 1, ""},
		{"Buffer", Type, 0, ""},
		{"Clone", Func, 20, "func(b []byte) []byte"},
		{"Compare", Func, 0, "func(a []byte, b []byte) int"},
		{"Contains", Func, 0, "func(b []byte, subslice []byte) bool"},
		{"ContainsAny", Func, 7, "func(b []byte, chars string) bool"},
		{"ContainsFunc", Func, 21, "func(b []byte, f func(rune) bool) bool"},
		{"ContainsRune", Func, 7, "func(b []byte, r rune) bool"},
		{"Count", Func, 0, "func(s []byte, sep []byte) int"},
		{"Cut", Func, 18, "func(s []byte, sep []byte) (before []byte, after []byte, found bool)"},
		{"CutPrefix", Func, 20, "func(s []byte, prefix []byte) (after []byte, found bool)"},
		{"CutSuffix", Func, 20, "func(s []byte, suffix []byte) (before []byte, found bool)"},
		{"Equal", Func, 0, "func(a []byte, b []byte) bool"},
		{"EqualFold", Func, 0, "func(s []byte, t []byte) bool"},
		{"ErrTooLarge", Var, 0, ""},
		{"Fields", Func, 0, "func(s []byte) [][]byte"},
		{"FieldsFunc", Func, 0, "func(s []byte, f func(rune) bool) [][]byte"},
		{"FieldsFuncSeq", Func, 24, "func(s []byte, f func(rune) bool) iter.Seq[[]byte]"},
		{"FieldsSeq", Func, 24, "func(s []byte) iter.Seq[[]byte]"},
		{"HasPrefix", Func, 0, "func(s []byte, prefix []byte) bool"},
		{"HasSuffix", Func, 0, "func(s []byte, suffix []byte) bool"},
		{"Index", Func, 0, "func(s []byte, sep []byte) int"},
		{"IndexAny", Func, 0, "func(s []byte, chars string) int"},
		{"IndexByte", Func, 0, "func(b []byte, c byte) int"},
		{"IndexFunc", Func, 0, "func(s []byte, f func(r rune) bool) int"},
		{"IndexRune", Func, 0, "func(s []byte, r rune) int"},
		{"Join", Func, 0, "func(s [][]byte, sep []byte) []byte"},
		{"LastIndex", Func, 0, "func(s []byte, sep []byte) int"},
		{"LastIndexAny", Func, 0, "func(s []byte, chars string) int"},
		{"LastIndexByte", Func, 5, "func(s []byte, c byte) int"},
		{"LastIndexFunc", Func, 0, "func(s []byte, f func(r rune) bool) int"},
		{"Lines", Func, 24, "func(s []byte) iter.Seq[[]byte]"},
		{"Map", Func, 0, "func(mapping func(r rune) rune, s []byte) []byte"},
		{"MinRead", Const, 0, ""},
		{"NewBuffer", Func, 0, "func(buf []byte) *Buffer"},
		{"NewBufferString", Func, 0, "func(s string) *Buffer"},
		{"NewReader", Func, 0, "func(b []byte) *Reader"},
		{"Reader", Type, 0, ""},
		{"Repeat", Func, 0, "func(b []byte, count int) []byte"},
		{"Replace", Func, 0, "func(s []byte, old []byte, new []byte, n int) []byte"},
		{"ReplaceAll", Func, 12, "func(s []byte, old []byte, new []byte) []byte"},
		{"Runes", Func, 0, "func(s []byte) []rune"},
		{"Split", Func, 0, "func(s []byte, sep []byte) [][]byte"},
		{"SplitAfter", Func, 0, "func(s []byte, sep []byte) [][]byte"},
		{"SplitAfterN", Func, 0, "func(s []byte, sep []byte, n int) [][]byte"},
		{"SplitAfterSeq", Func, 24, "func(s []byte, sep []byte) iter.Seq[[]byte]"},
		{"SplitN", Func, 0, "func(s []byte, sep []byte, n int) [][]byte"},
		{"SplitSeq", Func, 24, "func(s []byte, sep []byte) iter.Seq[[]byte]"},
		{"Title", Func, 0, "func(s []byte) []byte"},
		{"ToLower", Func, 0, "func(s []byte) []byte"},
		{"ToLowerSpecial", Func, 0, "func(c unicode.SpecialCase, s []byte) []byte"},
		{"ToTitle", Func, 0, "func(s []byte) []byte"},
		{"ToTitleSpecial", Func, 0, "func(c unicode.SpecialCase, s []byte) []byte"},
		{"ToUpper", Func, 0, "func(s []byte) []byte"},
		{"ToUpperSpecial", Func, 0, "func(c unicode.SpecialCase, s []byte) []byte"},
		{"ToValidUTF8", Func, 13, "func(s []byte, replacement []byte) []byte"},
		{"Trim", Func, 0, "func(s []byte, cutset string) []byte"},
		{"TrimFunc", Func, 0, "func(s []byte, f func(r rune) bool) []byte"},
		{"TrimLeft", Func, 0, "func(s []byte, cutset string) []byte"},
		{"TrimLeftFunc", Func, 0, "func(s []byte, f func(r rune) bool) []byte"},
		{"TrimPrefix", Func, 1, "func(s []byte, prefix []byte) []byte"},
		{"TrimRight", Func, 0, "func(s []byte, cutset string) []byte"},
		{"TrimRightFunc", Func, 0, "func(s []byte, f func(r rune) bool) []byte"},
		{"TrimSpace", Func, 0, "func(s []byte) []byte"},
		{"TrimSuffix", Func, 1, "func(s []byte, suffix []byte) []byte"},
	},
	"cmp": {
		{"Compare", Func, 21, "func[T Ordered](x T, y T) int"},
		{"Less", Func, 21, "func[T Ordered](x T, y T) bool"},
		{"Or", Func, 22, "func[T comparable](vals ...T) T"},
		{"Ordered", Type, 21, ""},
	},
	"compress/bzip2": {
		{"(StructuralError).Error", Method, 0, ""},
		{"NewReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"StructuralError", Type, 0, ""},
	},
	"compress/flate": {
		{"(*ReadError).Error", Method, 0, ""},
		{"(*WriteError).Error", Method, 0, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).Reset", Method, 2, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"(CorruptInputError).Error", Method, 0, ""},
		{"(InternalError).Error", Method, 0, ""},
		{"(Reader).Read", Method, 0, ""},
		{"(Reader).ReadByte", Method, 0, ""},
		{"(Resetter).Reset", Method, 4, ""},
		{"BestCompression", Const, 0, ""},
		{"BestSpeed", Const, 0, ""},
		{"CorruptInputError", Type, 0, ""},
		{"DefaultCompression", Const, 0, ""},
		{"HuffmanOnly", Const, 7, ""},
		{"InternalError", Type, 0, ""},
		{"NewReader", Func, 0, "func(r io.Reader) io.ReadCloser"},
		{"NewReaderDict", Func, 0, "func(r io.Reader, dict []byte) io.ReadCloser"},
		{"NewWriter", Func, 0, "func(w io.Writer, level int) (*Writer, error)"},
		{"NewWriterDict", Func, 0, "func(w io.Writer, level int, dict []byte) (*Writer, error)"},
		{"NoCompression", Const, 0, ""},
		{"ReadError", Type, 0, ""},
		{"ReadError.Err", Field, 0, ""},
		{"ReadError.Offset", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"Resetter", Type, 4, ""},
		{"WriteError", Type, 0, ""},
		{"WriteError.Err", Field, 0, ""},
		{"WriteError.Offset", Field, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"compress/gzip": {
		{"(*Reader).Close", Method, 0, ""},
		{"(*Reader).Multistream", Method, 4, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Reader).Reset", Method, 3, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Flush", Method, 1, ""},
		{"(*Writer).Reset", Method, 2, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"BestCompression", Const, 0, ""},
		{"BestSpeed", Const, 0, ""},
		{"DefaultCompression", Const, 0, ""},
		{"ErrChecksum", Var, 0, ""},
		{"ErrHeader", Var, 0, ""},
		{"Header", Type, 0, ""},
		{"Header.Comment", Field, 0, ""},
		{"Header.Extra", Field, 0, ""},
		{"Header.ModTime", Field, 0, ""},
		{"Header.Name", Field, 0, ""},
		{"Header.OS", Field, 0, ""},
		{"HuffmanOnly", Const, 8, ""},
		{"NewReader", Func, 0, "func(r io.Reader) (*Reader, error)"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"NewWriterLevel", Func, 0, "func(w io.Writer, level int) (*Writer, error)"},
		{"NoCompression", Const, 0, ""},
		{"Reader", Type, 0, ""},
		{"Reader.Header", Field, 0, ""},
		{"Writer", Type, 0, ""},
		{"Writer.Header", Field, 0, ""},
	},
	"compress/lzw": {
		{"(*Reader).Close", Method, 17, ""},
		{"(*Reader).Read", Method, 17, ""},
		{"(*Reader).Reset", Method, 17, ""},
		{"(*Writer).Close", Method, 17, ""},
		{"(*Writer).Reset", Method, 17, ""},
		{"(*Writer).Write", Method, 17, ""},
		{"LSB", Const, 0, ""},
		{"MSB", Const, 0, ""},
		{"NewReader", Func, 0, "func(r io.Reader, order Order, litWidth int) io.ReadCloser"},
		{"NewWriter", Func, 0, "func(w io.Writer, order Order, litWidth int) io.WriteCloser"},
		{"Order", Type, 0, ""},
		{"Reader", Type, 17, ""},
		{"Writer", Type, 17, ""},
	},
	"compress/zlib": {
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).Reset", Method, 2, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"(Resetter).Reset", Method, 4, ""},
		{"BestCompression", Const, 0, ""},
		{"BestSpeed", Const, 0, ""},
		{"DefaultCompression", Const, 0, ""},
		{"ErrChecksum", Var, 0, ""},
		{"ErrDictionary", Var, 0, ""},
		{"ErrHeader", Var, 0, ""},
		{"HuffmanOnly", Const, 8, ""},
		{"NewReader", Func, 0, "func(r io.Reader) (io.ReadCloser, error)"},
		{"NewReaderDict", Func, 0, "func(r io.Reader, dict []byte) (io.ReadCloser, error)"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"NewWriterLevel", Func, 0, "func(w io.Writer, level int) (*Writer, error)"},
		{"NewWriterLevelDict", Func, 0, "func(w io.Writer, level int, dict []byte) (*Writer, error)"},
		{"NoCompression", Const, 0, ""},
		{"Resetter", Type, 4, ""},
		{"Writer", Type, 0, ""},
	},
	"container/heap": {
		{"(Interface).Len", Method, 0, ""},
		{"(Interface).Less", Method, 0, ""},
		{"(Interface).Pop", Method, 0, ""},
		{"(Interface).Push", Method, 0, ""},
		{"(Interface).Swap", Method, 0, ""},
		{"Fix", Func, 2, "func(h Interface, i int)"},
		{"Init", Func, 0, "func(h Interface)"},
		{"Interface", Type, 0, ""},
		{"Pop", Func, 0, "func(h Interface) any"},
		{"Push", Func, 0, "func(h Interface, x any)"},
		{"Remove", Func, 0, "func(h Interface, i int) any"},
	},
	"container/list": {
		{"(*Element).Next", Method, 0, ""},
		{"(*Element).Prev", Method, 0, ""},
		{"(*List).Back", Method, 0, ""},
		{"(*List).Front", Method, 0, ""},
		{"(*List).Init", Method, 0, ""},
		{"(*List).InsertAfter", Method, 0, ""},
		{"(*List).InsertBefore", Method, 0, ""},
		{"(*List).Len", Method, 0, ""},
		{"(*List).MoveAfter", Method, 2, ""},
		{"(*List).MoveBefore", Method, 2, ""},
		{"(*List).MoveToBack", Method, 0, ""},
		{"(*List).MoveToFront", Method, 0, ""},
		{"(*List).PushBack", Method, 0, ""},
		{"(*List).PushBackList", Method, 0, ""},
		{"(*List).PushFront", Method, 0, ""},
		{"(*List).PushFrontList", Method, 0, ""},
		{"(*List).Remove", Method, 0, ""},
		{"Element", Type, 0, ""},
		{"Element.Value", Field, 0, ""},
		{"List", Type, 0, ""},
		{"New", Func, 0, "func() *List"},
	},
	"container/ring": {
		{"(*Ring).Do", Method, 0, ""},
		{"(*Ring).Len", Method, 0, ""},
		{"(*Ring).Link", Method, 0, ""},
		{"(*Ring).Move", Method, 0, ""},
		{"(*Ring).Next", Method, 0, ""},
		{"(*Ring).Prev", Method, 0, ""},
		{"(*Ring).Unlink", Method, 0, ""},
		{"New", Func, 0, "func(n int) *Ring"},
		{"Ring", Type, 0, ""},
		{"Ring.Value", Field, 0, ""},
	},
	"context": {
		{"(Context).Deadline", Method, 7, ""},
		{"(Context).Done", Method, 7, ""},
		{"(Context).Err", Method, 7, ""},
		{"(Context).Value", Method, 7, ""},
		{"AfterFunc", Func, 21, "func(ctx Context, f func()) (stop func() bool)"},
		{"Background", Func, 7, "func() Context"},
		{"CancelCauseFunc", Type, 20, ""},
		{"CancelFunc", Type, 7, ""},
		{"Canceled", Var, 7, ""},
		{"Cause", Func, 20, "func(c Context) error"},
		{"Context", Type, 7, ""},
		{"DeadlineExceeded", Var, 7, ""},
		{"TODO", Func, 7, "func() Context"},
		{"WithCancel", Func, 7, "func(parent Context) (ctx Context, cancel CancelFunc)"},
		{"WithCancelCause", Func, 20, "func(parent Context) (ctx Context, cancel CancelCauseFunc)"},
		{"WithDeadline", Func, 7, "func(parent Context, d time.Time) (Context, CancelFunc)"},
		{"WithDeadlineCause", Func, 21, "func(parent Context, d time.Time, cause error) (Context, CancelFunc)"},
		{"WithTimeout", Func, 7, "func(parent Context, timeout time.Duration) (Context, CancelFunc)"},
		{"WithTimeoutCause", Func, 21, "func(parent Context, timeout time.Duration, cause error) (Context, CancelFunc)"},
		{"WithValue", Func, 7, "func(parent Context, key any, val any) Context"},
		{"WithoutCancel", Func, 21, "func(parent Context) Context"},
	},
	"crypto": {
		{"(Decapsulator).Decapsulate", Method, 26, ""},
		{"(Decapsulator).Encapsulator", Method, 26, ""},
		{"(Decrypter).Decrypt", Method, 5, ""},
		{"(Decrypter).Public", Method, 5, ""},
		{"(Encapsulator).Bytes", Method, 26, ""},
		{"(Encapsulator).Encapsulate", Method, 26, ""},
		{"(Hash).Available", Method, 0, ""},
		{"(Hash).HashFunc", Method, 4, ""},
		{"(Hash).New", Method, 0, ""},
		{"(Hash).Size", Method, 0, ""},
		{"(Hash).String", Method, 15, ""},
		{"(MessageSigner).Public", Method, 25, ""},
		{"(MessageSigner).Sign", Method, 25, ""},
		{"(MessageSigner).SignMessage", Method, 25, ""},
		{"(Signer).Public", Method, 4, ""},
		{"(Signer).Sign", Method, 4, ""},
		{"(SignerOpts).HashFunc", Method, 4, ""},
		{"BLAKE2b_256", Const, 9, ""},
		{"BLAKE2b_384", Const, 9, ""},
		{"BLAKE2b_512", Const, 9, ""},
		{"BLAKE2s_256", Const, 9, ""},
		{"Decapsulator", Type, 26, ""},
		{"Decrypter", Type, 5, ""},
		{"DecrypterOpts", Type, 5, ""},
		{"Encapsulator", Type, 26, ""},
		{"Hash", Type, 0, ""},
		{"MD4", Const, 0, ""},
		{"MD5", Const, 0, ""},
		{"MD5SHA1", Const, 0, ""},
		{"MessageSigner", Type, 25, ""},
		{"PrivateKey", Type, 0, ""},
		{"PublicKey", Type, 2, ""},
		{"RIPEMD160", Const, 0, ""},
		{"RegisterHash", Func, 0, "func(h Hash, f func() hash.Hash)"},
		{"SHA1", Const, 0, ""},
		{"SHA224", Const, 0, ""},
		{"SHA256", Const, 0, ""},
		{"SHA384", Const, 0, ""},
		{"SHA3_224", Const, 4, ""},
		{"SHA3_256", Const, 4, ""},
		{"SHA3_384", Const, 4, ""},
		{"SHA3_512", Const, 4, ""},
		{"SHA512", Const, 0, ""},
		{"SHA512_224", Const, 5, ""},
		{"SHA512_256", Const, 5, ""},
		{"SignMessage", Func, 25, "func(signer Signer, rand io.Reader, msg []byte, opts SignerOpts) (signature []byte, err error)"},
		{"Signer", Type, 4, ""},
		{"SignerOpts", Type, 4, ""},
	},
	"crypto/aes": {
		{"(KeySizeError).Error", Method, 0, ""},
		{"BlockSize", Const, 0, ""},
		{"KeySizeError", Type, 0, ""},
		{"NewCipher", Func, 0, "func(key []byte) (cipher.Block, error)"},
	},
	"crypto/cipher": {
		{"(AEAD).NonceSize", Method, 2, ""},
		{"(AEAD).Open", Method, 2, ""},
		{"(AEAD).Overhead", Method, 2, ""},
		{"(AEAD).Seal", Method, 2, ""},
		{"(Block).BlockSize", Method, 0, ""},
		{"(Block).Decrypt", Method, 0, ""},
		{"(Block).Encrypt", Method, 0, ""},
		{"(BlockMode).BlockSize", Method, 0, ""},
		{"(BlockMode).CryptBlocks", Method, 0, ""},
		{"(Stream).XORKeyStream", Method, 0, ""},
		{"(StreamReader).Read", Method, 0, ""},
		{"(StreamWriter).Close", Method, 0, ""},
		{"(StreamWriter).Write", Method, 0, ""},
		{"AEAD", Type, 2, ""},
		{"Block", Type, 0, ""},
		{"BlockMode", Type, 0, ""},
		{"NewCBCDecrypter", Func, 0, "func(b Block, iv []byte) BlockMode"},
		{"NewCBCEncrypter", Func, 0, "func(b Block, iv []byte) BlockMode"},
		{"NewCFBDecrypter", Func, 0, "func(block Block, iv []byte) Stream"},
		{"NewCFBEncrypter", Func, 0, "func(block Block, iv []byte) Stream"},
		{"NewCTR", Func, 0, "func(block Block, iv []byte) Stream"},
		{"NewGCM", Func, 2, "func(cipher Block) (AEAD, error)"},
		{"NewGCMWithNonceSize", Func, 5, "func(cipher Block, size int) (AEAD, error)"},
		{"NewGCMWithRandomNonce", Func, 24, "func(cipher Block) (AEAD, error)"},
		{"NewGCMWithTagSize", Func, 11, "func(cipher Block, tagSize int) (AEAD, error)"},
		{"NewOFB", Func, 0, "func(b Block, iv []byte) Stream"},
		{"Stream", Type, 0, ""},
		{"StreamReader", Type, 0, ""},
		{"StreamReader.R", Field, 0, ""},
		{"StreamReader.S", Field, 0, ""},
		{"StreamWriter", Type, 0, ""},
		{"StreamWriter.Err", Field, 0, ""},
		{"StreamWriter.S", Field, 0, ""},
		{"StreamWriter.W", Field, 0, ""},
	},
	"crypto/des": {
		{"(KeySizeError).Error", Method, 0, ""},
		{"BlockSize", Const, 0, ""},
		{"KeySizeError", Type, 0, ""},
		{"NewCipher", Func, 0, "func(key []byte) (cipher.Block, error)"},
		{"NewTripleDESCipher", Func, 0, "func(key []byte) (cipher.Block, error)"},
	},
	"crypto/dsa": {
		{"ErrInvalidPublicKey", Var, 0, ""},
		{"GenerateKey", Func, 0, "func(priv *PrivateKey, rand io.Reader) error"},
		{"GenerateParameters", Func, 0, "func(params *Parameters, rand io.Reader, sizes ParameterSizes) error"},
		{"L1024N160", Const, 0, ""},
		{"L2048N224", Const, 0, ""},
		{"L2048N256", Const, 0, ""},
		{"L3072N256", Const, 0, ""},
		{"ParameterSizes", Type, 0, ""},
		{"Parameters", Type, 0, ""},
		{"Parameters.G", Field, 0, ""},
		{"Parameters.P", Field, 0, ""},
		{"Parameters.Q", Field, 0, ""},
		{"PrivateKey", Type, 0, ""},
		{"PrivateKey.PublicKey", Field, 0, ""},
		{"PrivateKey.X", Field, 0, ""},
		{"PublicKey", Type, 0, ""},
		{"PublicKey.Parameters", Field, 0, ""},
		{"PublicKey.Y", Field, 0, ""},
		{"Sign", Func, 0, "func(random io.Reader, priv *PrivateKey, hash []byte) (r *big.Int, s *big.Int, err error)"},
		{"Verify", Func, 0, "func(pub *PublicKey, hash []byte, r *big.Int, s *big.Int) bool"},
	},
	"crypto/ecdh": {
		{"(*PrivateKey).Bytes", Method, 20, ""},
		{"(*PrivateKey).Curve", Method, 20, ""},
		{"(*PrivateKey).ECDH", Method, 20, ""},
		{"(*PrivateKey).Equal", Method, 20, ""},
		{"(*PrivateKey).Public", Method, 20, ""},
		{"(*PrivateKey).PublicKey", Method, 20, ""},
		{"(*PublicKey).Bytes", Method, 20, ""},
		{"(*PublicKey).Curve", Method, 20, ""},
		{"(*PublicKey).Equal", Method, 20, ""},
		{"(Curve).GenerateKey", Method, 20, ""},
		{"(Curve).NewPrivateKey", Method, 20, ""},
		{"(Curve).NewPublicKey", Method, 20, ""},
		{"(KeyExchanger).Curve", Method, 26, ""},
		{"(KeyExchanger).ECDH", Method, 26, ""},
		{"(KeyExchanger).PublicKey", Method, 26, ""},
		{"KeyExchanger", Type, 26, ""},
		{"P256", Func, 20, "func() Curve"},
		{"P384", Func, 20, "func() Curve"},
		{"P521", Func, 20, "func() Curve"},
		{"PrivateKey", Type, 20, ""},
		{"PublicKey", Type, 20, ""},
		{"X25519", Func, 20, "func() Curve"},
	},
	"crypto/ecdsa": {
		{"(*PrivateKey).Bytes", Method, 25, ""},
		{"(*PrivateKey).ECDH", Method, 20, ""},
		{"(*PrivateKey).Equal", Method, 15, ""},
		{"(*PrivateKey).Public", Method, 4, ""},
		{"(*PrivateKey).Sign", Method, 4, ""},
		{"(*PublicKey).Bytes", Method, 25, ""},
		{"(*PublicKey).ECDH", Method, 20, ""},
		{"(*PublicKey).Equal", Method, 15, ""},
		{"(PrivateKey).Add", Method, 0, ""},
		{"(PrivateKey).Double", Method, 0, ""},
		{"(PrivateKey).IsOnCurve", Method, 0, ""},
		{"(PrivateKey).Params", Method, 0, ""},
		{"(PrivateKey).ScalarBaseMult", Method, 0, ""},
		{"(PrivateKey).ScalarMult", Method, 0, ""},
		{"(PublicKey).Add", Method, 0, ""},
		{"(PublicKey).Double", Method, 0, ""},
		{"(PublicKey).IsOnCurve", Method, 0, ""},
		{"(PublicKey).Params", Method, 0, ""},
		{"(PublicKey).ScalarBaseMult", Method, 0, ""},
		{"(PublicKey).ScalarMult", Method, 0, ""},
		{"GenerateKey", Func, 0, "func(c elliptic.Curve, r io.Reader) (*PrivateKey, error)"},
		{"ParseRawPrivateKey", Func, 25, "func(curve elliptic.Curve, data []byte) (*PrivateKey, error)"},
		{"ParseUncompressedPublicKey", Func, 25, "func(curve elliptic.Curve, data []byte) (*PublicKey, error)"},
		{"PrivateKey", Type, 0, ""},
		{"PrivateKey.D", Field, 0, ""},
		{"PrivateKey.PublicKey", Field, 0, ""},
		{"PublicKey", Type, 0, ""},
		{"PublicKey.Curve", Field, 0, ""},
		{"PublicKey.X", Field, 0, ""},
		{"PublicKey.Y", Field, 0, ""},
		{"Sign", Func, 0, "func(rand io.Reader, priv *PrivateKey, hash []byte) (r *big.Int, s *big.Int, err error)"},
		{"SignASN1", Func, 15, "func(r io.Reader, priv *PrivateKey, hash []byte) ([]byte, error)"},
		{"Verify", Func, 0, "func(pub *PublicKey, hash []byte, r *big.Int, s *big.Int) bool"},
		{"VerifyASN1", Func, 15, "func(pub *PublicKey, hash []byte, sig []byte) bool"},
	},
	"crypto/ed25519": {
		{"(*Options).HashFunc", Method, 20, ""},
		{"(PrivateKey).Equal", Method, 15, ""},
		{"(PrivateKey).Public", Method, 13, ""},
		{"(PrivateKey).Seed", Method, 13, ""},
		{"(PrivateKey).Sign", Method, 13, ""},
		{"(PublicKey).Equal", Method, 15, ""},
		{"GenerateKey", Func, 13, "func(random io.Reader) (PublicKey, PrivateKey, error)"},
		{"NewKeyFromSeed", Func, 13, "func(seed []byte) PrivateKey"},
		{"Options", Type, 20, ""},
		{"Options.Context", Field, 20, ""},
		{"Options.Hash", Field, 20, ""},
		{"PrivateKey", Type, 13, ""},
		{"PrivateKeySize", Const, 13, ""},
		{"PublicKey", Type, 13, ""},
		{"PublicKeySize", Const, 13, ""},
		{"SeedSize", Const, 13, ""},
		{"Sign", Func, 13, "func(privateKey PrivateKey, message []byte) []byte"},
		{"SignatureSize", Const, 13, ""},
		{"Verify", Func, 13, "func(publicKey PublicKey, message []byte, sig []byte) bool"},
		{"VerifyWithOptions", Func, 20, "func(publicKey PublicKey, message []byte, sig []byte, opts *Options) error"},
	},
	"crypto/elliptic": {
		{"(*CurveParams).Add", Method, 0, ""},
		{"(*CurveParams).Double", Method, 0, ""},
		{"(*CurveParams).IsOnCurve", Method, 0, ""},
		{"(*CurveParams).Params", Method, 0, ""},
		{"(*CurveParams).ScalarBaseMult", Method, 0, ""},
		{"(*CurveParams).ScalarMult", Method, 0, ""},
		{"(Curve).Add", Method, 0, ""},
		{"(Curve).Double", Method, 0, ""},
		{"(Curve).IsOnCurve", Method, 0, ""},
		{"(Curve).Params", Method, 0, ""},
		{"(Curve).ScalarBaseMult", Method, 0, ""},
		{"(Curve).ScalarMult", Method, 0, ""},
		{"Curve", Type, 0, ""},
		{"CurveParams", Type, 0, ""},
		{"CurveParams.B", Field, 0, ""},
		{"CurveParams.BitSize", Field, 0, ""},
		{"CurveParams.Gx", Field, 0, ""},
		{"CurveParams.Gy", Field, 0, ""},
		{"CurveParams.N", Field, 0, ""},
		{"CurveParams.Name", Field, 5, ""},
		{"CurveParams.P", Field, 0, ""},
		{"GenerateKey", Func, 0, "func(curve Curve, rand io.Reader) (priv []byte, x *big.Int, y *big.Int, err error)"},
		{"Marshal", Func, 0, "func(curve Curve, x *big.Int, y *big.Int) []byte"},
		{"MarshalCompressed", Func, 15, "func(curve Curve, x *big.Int, y *big.Int) []byte"},
		{"P224", Func, 0, "func() Curve"},
		{"P256", Func, 0, "func() Curve"},
		{"P384", Func, 0, "func() Curve"},
		{"P521", Func, 0, "func() Curve"},
		{"Unmarshal", Func, 0, "func(curve Curve, data []byte) (x *big.Int, y *big.Int)"},
		{"UnmarshalCompressed", Func, 15, "func(curve Curve, data []byte) (x *big.Int, y *big.Int)"},
	},
	"crypto/fips140": {
		{"Enabled", Func, 24, "func() bool"},
		{"Enforced", Func, 26, "func() bool"},
		{"Version", Func, 26, "func() string"},
		{"WithoutEnforcement", Func, 26, "func(f func())"},
	},
	"crypto/hkdf": {
		{"Expand", Func, 24, "func[H hash.Hash](h func() H, pseudorandomKey []byte, info string, keyLength int) ([]byte, error)"},
		{"Extract", Func, 24, "func[H hash.Hash](h func() H, secret []byte, salt []byte) ([]byte, error)"},
		{"Key", Func, 24, "func[Hash hash.Hash](h func() Hash, secret []byte, salt []byte, info string, keyLength int) ([]byte, error)"},
	},
	"crypto/hmac": {
		{"Equal", Func, 1, "func(mac1 []byte, mac2 []byte) bool"},
		{"New", Func, 0, "func(h func() hash.Hash, key []byte) hash.Hash"},
	},
	"crypto/hpke": {
		{"(*Recipient).Export", Method, 26, ""},
		{"(*Recipient).Open", Method, 26, ""},
		{"(*Sender).Export", Method, 26, ""},
		{"(*Sender).Seal", Method, 26, ""},
		{"(AEAD).ID", Method, 26, ""},
		{"(KDF).ID", Method, 26, ""},
		{"(KEM).DeriveKeyPair", Method, 26, ""},
		{"(KEM).GenerateKey", Method, 26, ""},
		{"(KEM).ID", Method, 26, ""},
		{"(KEM).NewPrivateKey", Method, 26, ""},
		{"(KEM).NewPublicKey", Method, 26, ""},
		{"(PrivateKey).Bytes", Method, 26, ""},
		{"(PrivateKey).KEM", Method, 26, ""},
		{"(PrivateKey).PublicKey", Method, 26, ""},
		{"(PublicKey).Bytes", Method, 26, ""},
		{"(PublicKey).KEM", Method, 26, ""},
		{"AES128GCM", Func, 26, "func() AEAD"},
		{"AES256GCM", Func, 26, "func() AEAD"},
		{"ChaCha20Poly1305", Func, 26, "func() AEAD"},
		{"DHKEM", Func, 26, "func(curve ecdh.Curve) KEM"},
		{"ExportOnly", Func, 26, "func() AEAD"},
		{"HKDFSHA256", Func, 26, "func() KDF"},
		{"HKDFSHA384", Func, 26, "func() KDF"},
		{"HKDFSHA512", Func, 26, "func() KDF"},
		{"MLKEM1024", Func, 26, "func() KEM"},
		{"MLKEM1024P384", Func, 26, "func() KEM"},
		{"MLKEM768", Func, 26, "func() KEM"},
		{"MLKEM768P256", Func, 26, "func() KEM"},
		{"MLKEM768X25519", Func, 26, "func() KEM"},
		{"NewAEAD", Func, 26, "func(id uint16) (AEAD, error)"},
		{"NewDHKEMPrivateKey", Func, 26, "func(priv ecdh.KeyExchanger) (PrivateKey, error)"},
		{"NewDHKEMPublicKey", Func, 26, "func(pub *ecdh.PublicKey) (PublicKey, error)"},
		{"NewHybridPrivateKey", Func, 26, "func(pq crypto.Decapsulator, t ecdh.KeyExchanger) (PrivateKey, error)"},
		{"NewHybridPublicKey", Func, 26, "func(pq crypto.Encapsulator, t *ecdh.PublicKey) (PublicKey, error)"},
		{"NewKDF", Func, 26, "func(id uint16) (KDF, error)"},
		{"NewKEM", Func, 26, "func(id uint16) (KEM, error)"},
		{"NewMLKEMPrivateKey", Func, 26, "func(priv crypto.Decapsulator) (PrivateKey, error)"},
		{"NewMLKEMPublicKey", Func, 26, "func(pub crypto.Encapsulator) (PublicKey, error)"},
		{"NewRecipient", Func, 26, "func(enc []byte, k PrivateKey, kdf KDF, aead AEAD, info []byte) (*Recipient, error)"},
		{"NewSender", Func, 26, "func(pk PublicKey, kdf KDF, aead AEAD, info []byte) (enc []byte, s *Sender, err error)"},
		{"Open", Func, 26, "func(k PrivateKey, kdf KDF, aead AEAD, info []byte, ciphertext []byte) ([]byte, error)"},
		{"Recipient", Type, 26, ""},
		{"SHAKE128", Func, 26, "func() KDF"},
		{"SHAKE256", Func, 26, "func() KDF"},
		{"Seal", Func, 26, "func(pk PublicKey, kdf KDF, aead AEAD, info []byte, plaintext []byte) ([]byte, error)"},
		{"Sender", Type, 26, ""},
	},
	"crypto/md5": {
		{"BlockSize", Const, 0, ""},
		{"New", Func, 0, "func() hash.Hash"},
		{"Size", Const, 0, ""},
		{"Sum", Func, 2, "func(data []byte) [16]byte"},
	},
	"crypto/mlkem": {
		{"(*DecapsulationKey1024).Bytes", Method, 24, ""},
		{"(*DecapsulationKey1024).Decapsulate", Method, 24, ""},
		{"(*DecapsulationKey1024).EncapsulationKey", Method, 24, ""},
		{"(*DecapsulationKey1024).Encapsulator", Method, 26, ""},
		{"(*DecapsulationKey768).Bytes", Method, 24, ""},
		{"(*DecapsulationKey768).Decapsulate", Method, 24, ""},
		{"(*DecapsulationKey768).EncapsulationKey", Method, 24, ""},
		{"(*DecapsulationKey768).Encapsulator", Method, 26, ""},
		{"(*EncapsulationKey1024).Bytes", Method, 24, ""},
		{"(*EncapsulationKey1024).Encapsulate", Method, 24, ""},
		{"(*EncapsulationKey768).Bytes", Method, 24, ""},
		{"(*EncapsulationKey768).Encapsulate", Method, 24, ""},
		{"CiphertextSize1024", Const, 24, ""},
		{"CiphertextSize768", Const, 24, ""},
		{"DecapsulationKey1024", Type, 24, ""},
		{"DecapsulationKey768", Type, 24, ""},
		{"EncapsulationKey1024", Type, 24, ""},
		{"EncapsulationKey768", Type, 24, ""},
		{"EncapsulationKeySize1024", Const, 24, ""},
		{"EncapsulationKeySize768", Const, 24, ""},
		{"GenerateKey1024", Func, 24, "func() (*DecapsulationKey1024, error)"},
		{"GenerateKey768", Func, 24, "func() (*DecapsulationKey768, error)"},
		{"NewDecapsulationKey1024", Func, 24, "func(seed []byte) (*DecapsulationKey1024, error)"},
		{"NewDecapsulationKey768", Func, 24, "func(seed []byte) (*DecapsulationKey768, error)"},
		{"NewEncapsulationKey1024", Func, 24, "func(encapsulationKey []byte) (*EncapsulationKey1024, error)"},
		{"NewEncapsulationKey768", Func, 24, "func(encapsulationKey []byte) (*EncapsulationKey768, error)"},
		{"SeedSize", Const, 24, ""},
		{"SharedKeySize", Const, 24, ""},
	},
	"crypto/mlkem/mlkemtest": {
		{"Encapsulate1024", Func, 26, "func(ek *mlkem.EncapsulationKey1024, random []byte) (sharedKey []byte, ciphertext []byte, err error)"},
		{"Encapsulate768", Func, 26, "func(ek *mlkem.EncapsulationKey768, random []byte) (sharedKey []byte, ciphertext []byte, err error)"},
	},
	"crypto/pbkdf2": {
		{"Key", Func, 24, "func[Hash hash.Hash](h func() Hash, password string, salt []byte, iter int, keyLength int) ([]byte, error)"},
	},
	"crypto/rand": {
		{"Int", Func, 0, "func(rand io.Reader, max *big.Int) (n *big.Int, err error)"},
		{"Prime", Func, 0, "func(r io.Reader, bits int) (*big.Int, error)"},
		{"Read", Func, 0, "func(b []byte) (n int, err error)"},
		{"Reader", Var, 0, ""},
		{"Text", Func, 24, "func() string"},
	},
	"crypto/rc4": {
		{"(*Cipher).Reset", Method, 0, ""},
		{"(*Cipher).XORKeyStream", Method, 0, ""},
		{"(KeySizeError).Error", Method, 0, ""},
		{"Cipher", Type, 0, ""},
		{"KeySizeError", Type, 0, ""},
		{"NewCipher", Func, 0, "func(key []byte) (*Cipher, error)"},
	},
	"crypto/rsa": {
		{"(*PSSOptions).HashFunc", Method, 4, ""},
		{"(*PrivateKey).Decrypt", Method, 5, ""},
		{"(*PrivateKey).Equal", Method, 15, ""},
		{"(*PrivateKey).Precompute", Method, 0, ""},
		{"(*PrivateKey).Public", Method, 4, ""},
		{"(*PrivateKey).Sign", Method, 4, ""},
		{"(*PrivateKey).Size", Method, 11, ""},
		{"(*PrivateKey).Validate", Method, 0, ""},
		{"(*PublicKey).Equal", Method, 15, ""},
		{"(*PublicKey).Size", Method, 11, ""},
		{"CRTValue", Type, 0, ""},
		{"CRTValue.Coeff", Field, 0, ""},
		{"CRTValue.Exp", Field, 0, ""},
		{"CRTValue.R", Field, 0, ""},
		{"DecryptOAEP", Func, 0, "func(hash hash.Hash, random io.Reader, priv *PrivateKey, ciphertext []byte, label []byte) ([]byte, error)"},
		{"DecryptPKCS1v15", Func, 0, "func(random io.Reader, priv *PrivateKey, ciphertext []byte) ([]byte, error)"},
		{"DecryptPKCS1v15SessionKey", Func, 0, "func(random io.Reader, priv *PrivateKey, ciphertext []byte, key []byte) error"},
		{"EncryptOAEP", Func, 0, "func(hash hash.Hash, random io.Reader, pub *PublicKey, msg []byte, label []byte) ([]byte, error)"},
		{"EncryptOAEPWithOptions", Func, 26, "func(random io.Reader, pub *PublicKey, msg []byte, opts *OAEPOptions) ([]byte, error)"},
		{"EncryptPKCS1v15", Func, 0, "func(random io.Reader, pub *PublicKey, msg []byte) ([]byte, error)"},
		{"ErrDecryption", Var, 0, ""},
		{"ErrMessageTooLong", Var, 0, ""},
		{"ErrVerification", Var, 0, ""},
		{"GenerateKey", Func, 0, "func(random io.Reader, bits int) (*PrivateKey, error)"},
		{"GenerateMultiPrimeKey", Func, 0, "func(random io.Reader, nprimes int, bits int) (*PrivateKey, error)"},
		{"OAEPOptions", Type, 5, ""},
		{"OAEPOptions.Hash", Field, 5, ""},
		{"OAEPOptions.Label", Field, 5, ""},
		{"OAEPOptions.MGFHash", Field, 20, ""},
		{"PKCS1v15DecryptOptions", Type, 5, ""},
		{"PKCS1v15DecryptOptions.SessionKeyLen", Field, 5, ""},
		{"PSSOptions", Type, 2, ""},
		{"PSSOptions.Hash", Field, 4, ""},
		{"PSSOptions.SaltLength", Field, 2, ""},
		{"PSSSaltLengthAuto", Const, 2, ""},
		{"PSSSaltLengthEqualsHash", Const, 2, ""},
		{"PrecomputedValues", Type, 0, ""},
		{"PrecomputedValues.CRTValues", Field, 0, ""},
		{"PrecomputedValues.Dp", Field, 0, ""},
		{"PrecomputedValues.Dq", Field, 0, ""},
		{"PrecomputedValues.Qinv", Field, 0, ""},
		{"PrivateKey", Type, 0, ""},
		{"PrivateKey.D", Field, 0, ""},
		{"PrivateKey.Precomputed", Field, 0, ""},
		{"PrivateKey.Primes", Field, 0, ""},
		{"PrivateKey.PublicKey", Field, 0, ""},
		{"PublicKey", Type, 0, ""},
		{"PublicKey.E", Field, 0, ""},
		{"PublicKey.N", Field, 0, ""},
		{"SignPKCS1v15", Func, 0, "func(random io.Reader, priv *PrivateKey, hash crypto.Hash, hashed []byte) ([]byte, error)"},
		{"SignPSS", Func, 2, "func(random io.Reader, priv *PrivateKey, hash crypto.Hash, digest []byte, opts *PSSOptions) ([]byte, error)"},
		{"VerifyPKCS1v15", Func, 0, "func(pub *PublicKey, hash crypto.Hash, hashed []byte, sig []byte) error"},
		{"VerifyPSS", Func, 2, "func(pub *PublicKey, hash crypto.Hash, digest []byte, sig []byte, opts *PSSOptions) error"},
	},
	"crypto/sha1": {
		{"BlockSize", Const, 0, ""},
		{"New", Func, 0, "func() hash.Hash"},
		{"Size", Const, 0, ""},
		{"Sum", Func, 2, "func(data []byte) [20]byte"},
	},
	"crypto/sha256": {
		{"BlockSize", Const, 0, ""},
		{"New", Func, 0, "func() hash.Hash"},
		{"New224", Func, 0, "func() hash.Hash"},
		{"Size", Const, 0, ""},
		{"Size224", Const, 0, ""},
		{"Sum224", Func, 2, "func(data []byte) [28]byte"},
		{"Sum256", Func, 2, "func(data []byte) [32]byte"},
	},
	"crypto/sha3": {
		{"(*SHA3).AppendBinary", Method, 24, ""},
		{"(*SHA3).BlockSize", Method, 24, ""},
		{"(*SHA3).Clone", Method, 25, ""},
		{"(*SHA3).MarshalBinary", Method, 24, ""},
		{"(*SHA3).Reset", Method, 24, ""},
		{"(*SHA3).Size", Method, 24, ""},
		{"(*SHA3).Sum", Method, 24, ""},
		{"(*SHA3).UnmarshalBinary", Method, 24, ""},
		{"(*SHA3).Write", Method, 24, ""},
		{"(*SHAKE).AppendBinary", Method, 24, ""},
		{"(*SHAKE).BlockSize", Method, 24, ""},
		{"(*SHAKE).MarshalBinary", Method, 24, ""},
		{"(*SHAKE).Read", Method, 24, ""},
		{"(*SHAKE).Reset", Method, 24, ""},
		{"(*SHAKE).UnmarshalBinary", Method, 24, ""},
		{"(*SHAKE).Write", Method, 24, ""},
		{"New224", Func, 24, "func() *SHA3"},
		{"New256", Func, 24, "func() *SHA3"},
		{"New384", Func, 24, "func() *SHA3"},
		{"New512", Func, 24, "func() *SHA3"},
		{"NewCSHAKE128", Func, 24, "func(N []byte, S []byte) *SHAKE"},
		{"NewCSHAKE256", Func, 24, "func(N []byte, S []byte) *SHAKE"},
		{"NewSHAKE128", Func, 24, "func() *SHAKE"},
		{"NewSHAKE256", Func, 24, "func() *SHAKE"},
		{"SHA3", Type, 24, ""},
		{"SHAKE", Type, 24, ""},
		{"Sum224", Func, 24, "func(data []byte) [28]byte"},
		{"Sum256", Func, 24, "func(data []byte) [32]byte"},
		{"Sum384", Func, 24, "func(data []byte) [48]byte"},
		{"Sum512", Func, 24, "func(data []byte) [64]byte"},
		{"SumSHAKE128", Func, 24, "func(data []byte, length int) []byte"},
		{"SumSHAKE256", Func, 24, "func(data []byte, length int) []byte"},
	},
	"crypto/sha512": {
		{"BlockSize", Const, 0, ""},
		{"New", Func, 0, "func() hash.Hash"},
		{"New384", Func, 0, "func() hash.Hash"},
		{"New512_224", Func, 5, "func() hash.Hash"},
		{"New512_256", Func, 5, "func() hash.Hash"},
		{"Size", Const, 0, ""},
		{"Size224", Const, 5, ""},
		{"Size256", Const, 5, ""},
		{"Size384", Const, 0, ""},
		{"Sum384", Func, 2, "func(data []byte) [48]byte"},
		{"Sum512", Func, 2, "func(data []byte) [64]byte"},
		{"Sum512_224", Func, 5, "func(data []byte) [28]byte"},
		{"Sum512_256", Func, 5, "func(data []byte) [32]byte"},
	},
	"crypto/subtle": {
		{"ConstantTimeByteEq", Func, 0, "func(x uint8, y uint8) int"},
		{"ConstantTimeCompare", Func, 0, "func(x []byte, y []byte) int"},
		{"ConstantTimeCopy", Func, 0, "func(v int, x []byte, y []byte)"},
		{"ConstantTimeEq", Func, 0, "func(x int32, y int32) int"},
		{"ConstantTimeLessOrEq", Func, 2, "func(x int, y int) int"},
		{"ConstantTimeSelect", Func, 0, "func(v int, x int, y int) int"},
		{"WithDataIndependentTiming", Func, 24, "func(f func())"},
		{"XORBytes", Func, 20, "func(dst []byte, x []byte, y []byte) int"},
	},
	"crypto/tls": {
		{"(*CertificateRequestInfo).Context", Method, 17, ""},
		{"(*CertificateRequestInfo).SupportsCertificate", Method, 14, ""},
		{"(*CertificateVerificationError).Error", Method, 20, ""},
		{"(*CertificateVerificationError).Unwrap", Method, 20, ""},
		{"(*ClientHelloInfo).Context", Method, 17, ""},
		{"(*ClientHelloInfo).SupportsCertificate", Method, 14, ""},
		{"(*ClientSessionState).ResumptionState", Method, 21, ""},
		{"(*Config).BuildNameToCertificate", Method, 0, ""},
		{"(*Config).Clone", Method, 8, ""},
		{"(*Config).DecryptTicket", Method, 21, ""},
		{"(*Config).EncryptTicket", Method, 21, ""},
		{"(*Config).SetSessionTicketKeys", Method, 5, ""},
		{"(*Conn).Close", Method, 0, ""},
		{"(*Conn).CloseWrite", Method, 8, ""},
		{"(*Conn).ConnectionState", Method, 0, ""},
		{"(*Conn).Handshake", Method, 0, ""},
		{"(*Conn).HandshakeContext", Method, 17, ""},
		{"(*Conn).LocalAddr", Method, 0, ""},
		{"(*Conn).NetConn", Method, 18, ""},
		{"(*Conn).OCSPResponse", Method, 0, ""},
		{"(*Conn).Read", Method, 0, ""},
		{"(*Conn).RemoteAddr", Method, 0, ""},
		{"(*Conn).SetDeadline", Method, 0, ""},
		{"(*Conn).SetReadDeadline", Method, 0, ""},
		{"(*Conn).SetWriteDeadline", Method, 0, ""},
		{"(*Conn).VerifyHostname", Method, 0, ""},
		{"(*Conn).Write", Method, 0, ""},
		{"(*ConnectionState).ExportKeyingMaterial", Method, 11, ""},
		{"(*Dialer).Dial", Method, 15, ""},
		{"(*Dialer).DialContext", Method, 15, ""},
		{"(*ECHRejectionError).Error", Method, 23, ""},
		{"(*QUICConn).Close", Method, 21, ""},
		{"(*QUICConn).ConnectionState", Method, 21, ""},
		{"(*QUICConn).HandleData", Method, 21, ""},
		{"(*QUICConn).NextEvent", Method, 21, ""},
		{"(*QUICConn).SendSessionTicket", Method, 21, ""},
		{"(*QUICConn).SetTransportParameters", Method, 21, ""},
		{"(*QUICConn).Start", Method, 21, ""},
		{"(*QUICConn).StoreSession", Method, 23, ""},
		{"(*SessionState).Bytes", Method, 21, ""},
		{"(AlertError).Error", Method, 21, ""},
		{"(ClientAuthType).String", Method, 15, ""},
		{"(ClientSessionCache).Get", Method, 3, ""},
		{"(ClientSessionCache).Put", Method, 3, ""},
		{"(CurveID).String", Method, 15, ""},
		{"(QUICEncryptionLevel).String", Method, 21, ""},
		{"(RecordHeaderError).Error", Method, 6, ""},
		{"(SignatureScheme).String", Method, 15, ""},
		{"AlertError", Type, 21, ""},
		{"Certificate", Type, 0, ""},
		{"Certificate.Certificate", Field, 0, ""},
		{"Certificate.Leaf", Field, 0, ""},
		{"Certificate.OCSPStaple", Field, 0, ""},
		{"Certificate.PrivateKey", Field, 0, ""},
		{"Certificate.SignedCertificateTimestamps", Field, 5, ""},
		{"Certificate.SupportedSignatureAlgorithms", Field, 14, ""},
		{"CertificateRequestInfo", Type, 8, ""},
		{"CertificateRequestInfo.AcceptableCAs", Field, 8, ""},
		{"CertificateRequestInfo.SignatureSchemes", Field, 8, ""},
		{"CertificateRequestInfo.Version", Field, 14, ""},
		{"CertificateVerificationError", Type, 20, ""},
		{"CertificateVerificationError.Err", Field, 20, ""},
		{"CertificateVerificationError.UnverifiedCertificates", Field, 20, ""},
		{"CipherSuite", Type, 14, ""},
		{"CipherSuite.ID", Field, 14, ""},
		{"CipherSuite.Insecure", Field, 14, ""},
		{"CipherSuite.Name", Field, 14, ""},
		{"CipherSuite.SupportedVersions", Field, 14, ""},
		{"CipherSuiteName", Func, 14, "func(id uint16) string"},
		{"CipherSuites", Func, 14, "func() []*CipherSuite"},
		{"Client", Func, 0, "func(conn net.Conn, config *Config) *Conn"},
		{"ClientAuthType", Type, 0, ""},
		{"ClientHelloInfo", Type, 4, ""},
		{"ClientHelloInfo.CipherSuites", Field, 4, ""},
		{"ClientHelloInfo.Conn", Field, 8, ""},
		{"ClientHelloInfo.Extensions", Field, 24, ""},
		{"ClientHelloInfo.HelloRetryRequest", Field, 26, ""},
		{"ClientHelloInfo.ServerName", Field, 4, ""},
		{"ClientHelloInfo.SignatureSchemes", Field, 8, ""},
		{"ClientHelloInfo.SupportedCurves", Field, 4, ""},
		{"ClientHelloInfo.SupportedPoints", Field, 4, ""},
		{"ClientHelloInfo.SupportedProtos", Field, 8, ""},
		{"ClientHelloInfo.SupportedVersions", Field, 8, ""},
		{"ClientSessionCache", Type, 3, ""},
		{"ClientSessionState", Type, 3, ""},
		{"Config", Type, 0, ""},
		{"Config.Certificates", Field, 0, ""},
		{"Config.CipherSuites", Field, 0, ""},
		{"Config.ClientAuth", Field, 0, ""},
		{"Config.ClientCAs", Field, 0, ""},
		{"Config.ClientSessionCache", Field, 3, ""},
		{"Config.CurvePreferences", Field, 3, ""},
		{"Config.DynamicRecordSizingDisabled", Field, 7, ""},
		{"Config.EncryptedClientHelloConfigList", Field, 23, ""},
		{"Config.EncryptedClientHelloKeys", Field, 24, ""},
		{"Config.EncryptedClientHelloRejectionVerify", Field, 23, ""},
		{"Config.GetCertificate", Field, 4, ""},
		{"Config.GetClientCertificate", Field, 8, ""},
		{"Config.GetConfigForClient", Field, 8, ""},
		{"Config.GetEncryptedClientHelloKeys", Field, 25, ""},
		{"Config.InsecureSkipVerify", Field, 0, ""},
		{"Config.KeyLogWriter", Field, 8, ""},
		{"Config.MaxVersion", Field, 2, ""},
		{"Config.MinVersion", Field, 2, ""},
		{"Config.NameToCertificate", Field, 0, ""},
		{"Config.NextProtos", Field, 0, ""},
		{"Config.PreferServerCipherSuites", Field, 1, ""},
		{"Config.Rand", Field, 0, ""},
		{"Config.Renegotiation", Field, 7, ""},
		{"Config.RootCAs", Field, 0, ""},
		{"Config.ServerName", Field, 0, ""},
		{"Config.SessionTicketKey", Field, 1, ""},
		{"Config.SessionTicketsDisabled", Field, 1, ""},
		{"Config.Time", Field, 0, ""},
		{"Config.UnwrapSession", Field, 21, ""},
		{"Config.VerifyConnection", Field, 15, ""},
		{"Config.VerifyPeerCertificate", Field, 8, ""},
		{"Config.WrapSession", Field, 21, ""},
		{"Conn", Type, 0, ""},
		{"ConnectionState", Type, 0, ""},
		{"ConnectionState.CipherSuite", Field, 0, ""},
		{"ConnectionState.CurveID", Field, 25, ""},
		{"ConnectionState.DidResume", Field, 1, ""},
		{"ConnectionState.ECHAccepted", Field, 23, ""},
		{"ConnectionState.HandshakeComplete", Field, 0, ""},
		{"ConnectionState.HelloRetryRequest", Field, 26, ""},
		{"ConnectionState.NegotiatedProtocol", Field, 0, ""},
		{"ConnectionState.NegotiatedProtocolIsMutual", Field, 0, ""},
		{"ConnectionState.OCSPResponse", Field, 5, ""},
		{"ConnectionState.PeerCertificates", Field, 0, ""},
		{"ConnectionState.ServerName", Field, 0, ""},
		{"ConnectionState.SignedCertificateTimestamps", Field, 5, ""},
		{"ConnectionState.TLSUnique", Field, 4, ""},
		{"ConnectionState.VerifiedChains", Field, 0, ""},
		{"ConnectionState.Version", Field, 3, ""},
		{"CurveID", Type, 3, ""},
		{"CurveP256", Const, 3, ""},
		{"CurveP384", Const, 3, ""},
		{"CurveP521", Const, 3, ""},
		{"Dial", Func, 0, "func(network string, addr string, config *Config) (*Conn, error)"},
		{"DialWithDialer", Func, 3, "func(dialer *net.Dialer, network string, addr string, config *Config) (*Conn, error)"},
		{"Dialer", Type, 15, ""},
		{"Dialer.Config", Field, 15, ""},
		{"Dialer.NetDialer", Field, 15, ""},
		{"ECDSAWithP256AndSHA256", Const, 8, ""},
		{"ECDSAWithP384AndSHA384", Const, 8, ""},
		{"ECDSAWithP521AndSHA512", Const, 8, ""},
		{"ECDSAWithSHA1", Const, 10, ""},
		{"ECHRejectionError", Type, 23, ""},
		{"ECHRejectionError.RetryConfigList", Field, 23, ""},
		{"Ed25519", Const, 13, ""},
		{"EncryptedClientHelloKey", Type, 24, ""},
		{"EncryptedClientHelloKey.Config", Field, 24, ""},
		{"EncryptedClientHelloKey.PrivateKey", Field, 24, ""},
		{"EncryptedClientHelloKey.SendAsRetry", Field, 24, ""},
		{"InsecureCipherSuites", Func, 14, "func() []*CipherSuite"},
		{"Listen", Func, 0, "func(network string, laddr string, config *Config) (net.Listener, error)"},
		{"LoadX509KeyPair", Func, 0, "func(certFile string, keyFile string) (Certificate, error)"},
		{"NewLRUClientSessionCache", Func, 3, "func(capacity int) ClientSessionCache"},
		{"NewListener", Func, 0, "func(inner net.Listener, config *Config) net.Listener"},
		{"NewResumptionState", Func, 21, "func(ticket []byte, state *SessionState) (*ClientSessionState, error)"},
		{"NoClientCert", Const, 0, ""},
		{"PKCS1WithSHA1", Const, 8, ""},
		{"PKCS1WithSHA256", Const, 8, ""},
		{"PKCS1WithSHA384", Const, 8, ""},
		{"PKCS1WithSHA512", Const, 8, ""},
		{"PSSWithSHA256", Const, 8, ""},
		{"PSSWithSHA384", Const, 8, ""},
		{"PSSWithSHA512", Const, 8, ""},
		{"ParseSessionState", Func, 21, "func(data []byte) (*SessionState, error)"},
		{"QUICClient", Func, 21, "func(config *QUICConfig) *QUICConn"},
		{"QUICConfig", Type, 21, ""},
		{"QUICConfig.EnableSessionEvents", Field, 23, ""},
		{"QUICConfig.TLSConfig", Field, 21, ""},
		{"QUICConn", Type, 21, ""},
		{"QUICEncryptionLevel", Type, 21, ""},
		{"QUICEncryptionLevelApplication", Const, 21, ""},
		{"QUICEncryptionLevelEarly", Const, 21, ""},
		{"QUICEncryptionLevelHandshake", Const, 21, ""},
		{"QUICEncryptionLevelInitial", Const, 21, ""},
		{"QUICErrorEvent", Const, 26, ""},
		{"QUICEvent", Type, 21, ""},
		{"QUICEvent.Data", Field, 21, ""},
		{"QUICEvent.Err", Field, 26, ""},
		{"QUICEvent.Kind", Field, 21, ""},
		{"QUICEvent.Level", Field, 21, ""},
		{"QUICEvent.SessionState", Field, 23, ""},
		{"QUICEvent.Suite", Field, 21, ""},
		{"QUICEventKind", Type, 21, ""},
		{"QUICHandshakeDone", Const, 21, ""},
		{"QUICNoEvent", Const, 21, ""},
		{"QUICRejectedEarlyData", Const, 21, ""},
		{"QUICResumeSession", Const, 23, ""},
		{"QUICServer", Func, 21, "func(config *QUICConfig) *QUICConn"},
		{"QUICSessionTicketOptions", Type, 21, ""},
		{"QUICSessionTicketOptions.EarlyData", Field, 21, ""},
		{"QUICSessionTicketOptions.Extra", Field, 23, ""},
		{"QUICSetReadSecret", Const, 21, ""},
		{"QUICSetWriteSecret", Const, 21, ""},
		{"QUICStoreSession", Const, 23, ""},
		{"QUICTransportParameters", Const, 21, ""},
		{"QUICTransportParametersRequired", Const, 21, ""},
		{"QUICWriteData", Const, 21, ""},
		{"RecordHeaderError", Type, 6, ""},
		{"RecordHeaderError.Conn", Field, 12, ""},
		{"RecordHeaderError.Msg", Field, 6, ""},
		{"RecordHeaderError.RecordHeader", Field, 6, ""},
		{"RenegotiateFreelyAsClient", Const, 7, ""},
		{"RenegotiateNever", Const, 7, ""},
		{"RenegotiateOnceAsClient", Const, 7, ""},
		{"RenegotiationSupport", Type, 7, ""},
		{"RequestClientCert", Const, 0, ""},
		{"RequireAndVerifyClientCert", Const, 0, ""},
		{"RequireAnyClientCert", Const, 0, ""},
		{"SecP256r1MLKEM768", Const, 26, ""},
		{"SecP384r1MLKEM1024", Const, 26, ""},
		{"Server", Func, 0, "func(conn net.Conn, config *Config) *Conn"},
		{"SessionState", Type, 21, ""},
		{"SessionState.EarlyData", Field, 21, ""},
		{"SessionState.Extra", Field, 21, ""},
		{"SignatureScheme", Type, 8, ""},
		{"TLS_AES_128_GCM_SHA256", Const, 12, ""},
		{"TLS_AES_256_GCM_SHA384", Const, 12, ""},
		{"TLS_CHACHA20_POLY1305_SHA256", Const, 12, ""},
		{"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA", Const, 2, ""},
		{"TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256", Const, 8, ""},
		{"TLS_ECDHE_ECDSA_WITH_AES_128_GCM_SHA256", Const, 2, ""},
		{"TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA", Const, 2, ""},
		{"TLS_ECDHE_ECDSA_WITH_AES_256_GCM_SHA384", Const, 5, ""},
		{"TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305", Const, 8, ""},
		{"TLS_ECDHE_ECDSA_WITH_CHACHA20_POLY1305_SHA256", Const, 14, ""},
		{"TLS_ECDHE_ECDSA_WITH_RC4_128_SHA", Const, 2, ""},
		{"TLS_ECDHE_RSA_WITH_3DES_EDE_CBC_SHA", Const, 0, ""},
		{"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA", Const, 0, ""},
		{"TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256", Const, 8, ""},
		{"TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256", Const, 2, ""},
		{"TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA", Const, 1, ""},
		{"TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384", Const, 5, ""},
		{"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305", Const, 8, ""},
		{"TLS_ECDHE_RSA_WITH_CHACHA20_POLY1305_SHA256", Const, 14, ""},
		{"TLS_ECDHE_RSA_WITH_RC4_128_SHA", Const, 0, ""},
		{"TLS_FALLBACK_SCSV", Const, 4, ""},
		{"TLS_RSA_WITH_3DES_EDE_CBC_SHA", Const, 0, ""},
		{"TLS_RSA_WITH_AES_128_CBC_SHA", Const, 0, ""},
		{"TLS_RSA_WITH_AES_128_CBC_SHA256", Const, 8, ""},
		{"TLS_RSA_WITH_AES_128_GCM_SHA256", Const, 6, ""},
		{"TLS_RSA_WITH_AES_256_CBC_SHA", Const, 1, ""},
		{"TLS_RSA_WITH_AES_256_GCM_SHA384", Const, 6, ""},
		{"TLS_RSA_WITH_RC4_128_SHA", Const, 0, ""},
		{"VerifyClientCertIfGiven", Const, 0, ""},
		{"VersionName", Func, 21, "func(version uint16) string"},
		{"VersionSSL30", Const, 2, ""},
		{"VersionTLS10", Const, 2, ""},
		{"VersionTLS11", Const, 2, ""},
		{"VersionTLS12", Const, 2, ""},
		{"VersionTLS13", Const, 12, ""},
		{"X25519", Const, 8, ""},
		{"X25519MLKEM768", Const, 24, ""},
		{"X509KeyPair", Func, 0, "func(certPEMBlock []byte, keyPEMBlock []byte) (Certificate, error)"},
	},
	"crypto/x509": {
		{"(*CertPool).AddCert", Method, 0, ""},
		{"(*CertPool).AddCertWithConstraint", Method, 22, ""},
		{"(*CertPool).AppendCertsFromPEM", Method, 0, ""},
		{"(*CertPool).Clone", Method, 19, ""},
		{"(*CertPool).Equal", Method, 19, ""},
		{"(*CertPool).Subjects", Method, 0, ""},
		{"(*Certificate).CheckCRLSignature", Method, 0, ""},
		{"(*Certificate).CheckSignature", Method, 0, ""},
		{"(*Certificate).CheckSignatureFrom", Method, 0, ""},
		{"(*Certificate).CreateCRL", Method, 0, ""},
		{"(*Certificate).Equal", Method, 0, ""},
		{"(*Certificate).Verify", Method, 0, ""},
		{"(*Certificate).VerifyHostname", Method, 0, ""},
		{"(*CertificateRequest).CheckSignature", Method, 5, ""},
		{"(*OID).UnmarshalBinary", Method, 23, ""},
		{"(*OID).UnmarshalText", Method, 23, ""},
		{"(*RevocationList).CheckSignatureFrom", Method, 19, ""},
		{"(CertificateInvalidError).Error", Method, 0, ""},
		{"(ConstraintViolationError).Error", Method, 0, ""},
		{"(ExtKeyUsage).OID", Method, 26, ""},
		{"(ExtKeyUsage).String", Method, 26, ""},
		{"(HostnameError).Error", Method, 0, ""},
		{"(InsecureAlgorithmError).Error", Method, 6, ""},
		{"(KeyUsage).String", Method, 26, ""},
		{"(OID).AppendBinary", Method, 24, ""},
		{"(OID).AppendText", Method, 24, ""},
		{"(OID).Equal", Method, 22, ""},
		{"(OID).EqualASN1OID", Method, 22, ""},
		{"(OID).MarshalBinary", Method, 23, ""},
		{"(OID).MarshalText", Method, 23, ""},
		{"(OID).String", Method, 22, ""},
		{"(PublicKeyAlgorithm).String", Method, 10, ""},
		{"(SignatureAlgorithm).String", Method, 6, ""},
		{"(SystemRootsError).Error", Method, 1, ""},
		{"(SystemRootsError).Unwrap", Method, 16, ""},
		{"(UnhandledCriticalExtension).Error", Method, 0, ""},
		{"(UnknownAuthorityError).Error", Method, 0, ""},
		{"CANotAuthorizedForExtKeyUsage", Const, 10, ""},
		{"CANotAuthorizedForThisName", Const, 0, ""},
		{"CertPool", Type, 0, ""},
		{"Certificate", Type, 0, ""},
		{"Certificate.AuthorityKeyId", Field, 0, ""},
		{"Certificate.BasicConstraintsValid", Field, 0, ""},
		{"Certificate.CRLDistributionPoints", Field, 2, ""},
		{"Certificate.DNSNames", Field, 0, ""},
		{"Certificate.EmailAddresses", Field, 0, ""},
		{"Certificate.ExcludedDNSDomains", Field, 9, ""},
		{"Certificate.ExcludedEmailAddresses", Field, 10, ""},
		{"Certificate.ExcludedIPRanges", Field, 10, ""},
		{"Certificate.ExcludedURIDomains", Field, 10, ""},
		{"Certificate.ExtKeyUsage", Field, 0, ""},
		{"Certificate.Extensions", Field, 2, ""},
		{"Certificate.ExtraExtensions", Field, 2, ""},
		{"Certificate.IPAddresses", Field, 1, ""},
		{"Certificate.InhibitAnyPolicy", Field, 24, ""},
		{"Certificate.InhibitAnyPolicyZero", Field, 24, ""},
		{"Certificate.InhibitPolicyMapping", Field, 24, ""},
		{"Certificate.InhibitPolicyMappingZero", Field, 24, ""},
		{"Certificate.IsCA", Field, 0, ""},
		{"Certificate.Issuer", Field, 0, ""},
		{"Certificate.IssuingCertificateURL", Field, 2, ""},
		{"Certificate.KeyUsage", Field, 0, ""},
		{"Certificate.MaxPathLen", Field, 0, ""},
		{"Certificate.MaxPathLenZero", Field, 4, ""},
		{"Certificate.NotAfter", Field, 0, ""},
		{"Certificate.NotBefore", Field, 0, ""},
		{"Certificate.OCSPServer", Field, 2, ""},
		{"Certificate.PermittedDNSDomains", Field, 0, ""},
		{"Certificate.PermittedDNSDomainsCritical", Field, 0, ""},
		{"Certificate.PermittedEmailAddresses", Field, 10, ""},
		{"Certificate.PermittedIPRanges", Field, 10, ""},
		{"Certificate.PermittedURIDomains", Field, 10, ""},
		{"Certificate.Policies", Field, 22, ""},
		{"Certificate.PolicyIdentifiers", Field, 0, ""},
		{"Certificate.PolicyMappings", Field, 24, ""},
		{"Certificate.PublicKey", Field, 0, ""},
		{"Certificate.PublicKeyAlgorithm", Field, 0, ""},
		{"Certificate.Raw", Field, 0, ""},
		{"Certificate.RawIssuer", Field, 0, ""},
		{"Certificate.RawSubject", Field, 0, ""},
		{"Certificate.RawSubjectPublicKeyInfo", Field, 0, ""},
		{"Certificate.RawTBSCertificate", Field, 0, ""},
		{"Certificate.RequireExplicitPolicy", Field, 24, ""},
		{"Certificate.RequireExplicitPolicyZero", Field, 24, ""},
		{"Certificate.SerialNumber", Field, 0, ""},
		{"Certificate.Signature", Field, 0, ""},
		{"Certificate.SignatureAlgorithm", Field, 0, ""},
		{"Certificate.Subject", Field, 0, ""},
		{"Certificate.SubjectKeyId", Field, 0, ""},
		{"Certificate.URIs", Field, 10, ""},
		{"Certificate.UnhandledCriticalExtensions", Field, 5, ""},
		{"Certificate.UnknownExtKeyUsage", Field, 0, ""},
		{"Certificate.Version", Field, 0, ""},
		{"CertificateInvalidError", Type, 0, ""},
		{"CertificateInvalidError.Cert", Field, 0, ""},
		{"CertificateInvalidError.Detail", Field, 10, ""},
		{"CertificateInvalidError.Reason", Field, 0, ""},
		{"CertificateRequest", Type, 3, ""},
		{"CertificateRequest.Attributes", Field, 3, ""},
		{"CertificateRequest.DNSNames", Field, 3, ""},
		{"CertificateRequest.EmailAddresses", Field, 3, ""},
		{"CertificateRequest.Extensions", Field, 3, ""},
		{"CertificateRequest.ExtraExtensions", Field, 3, ""},
		{"CertificateRequest.IPAddresses", Field, 3, ""},
		{"CertificateRequest.PublicKey", Field, 3, ""},
		{"CertificateRequest.PublicKeyAlgorithm", Field, 3, ""},
		{"CertificateRequest.Raw", Field, 3, ""},
		{"CertificateRequest.RawSubject", Field, 3, ""},
		{"CertificateRequest.RawSubjectPublicKeyInfo", Field, 3, ""},
		{"CertificateRequest.RawTBSCertificateRequest", Field, 3, ""},
		{"CertificateRequest.Signature", Field, 3, ""},
		{"CertificateRequest.SignatureAlgorithm", Field, 3, ""},
		{"CertificateRequest.Subject", Field, 3, ""},
		{"CertificateRequest.URIs", Field, 10, ""},
		{"CertificateRequest.Version", Field, 3, ""},
		{"ConstraintViolationError", Type, 0, ""},
		{"CreateCertificate", Func, 0, "func(rand io.Reader, template *Certificate, parent *Certificate, pub any, priv any) ([]byte, error)"},
		{"CreateCertificateRequest", Func, 3, "func(rand io.Reader, template *CertificateRequest, priv any) (csr []byte, err error)"},
		{"CreateRevocationList", Func, 15, "func(rand io.Reader, template *RevocationList, issuer *Certificate, priv crypto.Signer) ([]byte, error)"},
		{"DSA", Const, 0, ""},
		{"DSAWithSHA1", Const, 0, ""},
		{"DSAWithSHA256", Const, 0, ""},
		{"DecryptPEMBlock", Func, 1, "func(b *pem.Block, password []byte) ([]byte, error)"},
		{"ECDSA", Const, 1, ""},
		{"ECDSAWithSHA1", Const, 1, ""},
		{"ECDSAWithSHA256", Const, 1, ""},
		{"ECDSAWithSHA384", Const, 1, ""},
		{"ECDSAWithSHA512", Const, 1, ""},
		{"Ed25519", Const, 13, ""},
		{"EncryptPEMBlock", Func, 1, "func(rand io.Reader, blockType string, data []byte, password []byte, alg PEMCipher) (*pem.Block, error)"},
		{"ErrUnsupportedAlgorithm", Var, 0, ""},
		{"Expired", Const, 0, ""},
		{"ExtKeyUsage", Type, 0, ""},
		{"ExtKeyUsageAny", Const, 0, ""},
		{"ExtKeyUsageClientAuth", Const, 0, ""},
		{"ExtKeyUsageCodeSigning", Const, 0, ""},
		{"ExtKeyUsageEmailProtection", Const, 0, ""},
		{"ExtKeyUsageIPSECEndSystem", Const, 1, ""},
		{"ExtKeyUsageIPSECTunnel", Const, 1, ""},
		{"ExtKeyUsageIPSECUser", Const, 1, ""},
		{"ExtKeyUsageMicrosoftCommercialCodeSigning", Const, 10, ""},
		{"ExtKeyUsageMicrosoftKernelCodeSigning", Const, 10, ""},
		{"ExtKeyUsageMicrosoftServerGatedCrypto", Const, 1, ""},
		{"ExtKeyUsageNetscapeServerGatedCrypto", Const, 1, ""},
		{"ExtKeyUsageOCSPSigning", Const, 0, ""},
		{"ExtKeyUsageServerAuth", Const, 0, ""},
		{"ExtKeyUsageTimeStamping", Const, 0, ""},
		{"HostnameError", Type, 0, ""},
		{"HostnameError.Certificate", Field, 0, ""},
		{"HostnameError.Host", Field, 0, ""},
		{"IncompatibleUsage", Const, 1, ""},
		{"IncorrectPasswordError", Var, 1, ""},
		{"InsecureAlgorithmError", Type, 6, ""},
		{"InvalidReason", Type, 0, ""},
		{"IsEncryptedPEMBlock", Func, 1, "func(b *pem.Block) bool"},
		{"KeyUsage", Type, 0, ""},
		{"KeyUsageCRLSign", Const, 0, ""},
		{"KeyUsageCertSign", Const, 0, ""},
		{"KeyUsageContentCommitment", Const, 0, ""},
		{"KeyUsageDataEncipherment", Const, 0, ""},
		{"KeyUsageDecipherOnly", Const, 0, ""},
		{"KeyUsageDigitalSignature", Const, 0, ""},
		{"KeyUsageEncipherOnly", Const, 0, ""},
		{"KeyUsageKeyAgreement", Const, 0, ""},
		{"KeyUsageKeyEncipherment", Const, 0, ""},
		{"MD2WithRSA", Const, 0, ""},
		{"MD5WithRSA", Const, 0, ""},
		{"MarshalECPrivateKey", Func, 2, "func(key *ecdsa.PrivateKey) ([]byte, error)"},
		{"MarshalPKCS1PrivateKey", Func, 0, "func(key *rsa.PrivateKey) []byte"},
		{"MarshalPKCS1PublicKey", Func, 10, "func(key *rsa.PublicKey) []byte"},
		{"MarshalPKCS8PrivateKey", Func, 10, "func(key any) ([]byte, error)"},
		{"MarshalPKIXPublicKey", Func, 0, "func(pub any) ([]byte, error)"},
		{"NameConstraintsWithoutSANs", Const, 10, ""},
		{"NameMismatch", Const, 8, ""},
		{"NewCertPool", Func, 0, "func() *CertPool"},
		{"NoValidChains", Const, 24, ""},
		{"NotAuthorizedToSign", Const, 0, ""},
		{"OID", Type, 22, ""},
		{"OIDFromASN1OID", Func, 26, "func(asn1OID asn1.ObjectIdentifier) (OID, error)"},
		{"OIDFromInts", Func, 22, "func(oid []uint64) (OID, error)"},
		{"PEMCipher", Type, 1, ""},
		{"PEMCipher3DES", Const, 1, ""},
		{"PEMCipherAES128", Const, 1, ""},
		{"PEMCipherAES192", Const, 1, ""},
		{"PEMCipherAES256", Const, 1, ""},
		{"PEMCipherDES", Const, 1, ""},
		{"ParseCRL", Func, 0, "func(crlBytes []byte) (*pkix.CertificateList, error)"},
		{"ParseCertificate", Func, 0, "func(der []byte) (*Certificate, error)"},
		{"ParseCertificateRequest", Func, 3, "func(asn1Data []byte) (*CertificateRequest, error)"},
		{"ParseCertificates", Func, 0, "func(der []byte) ([]*Certificate, error)"},
		{"ParseDERCRL", Func, 0, "func(derBytes []byte) (*pkix.CertificateList, error)"},
		{"ParseECPrivateKey", Func, 1, "func(der []byte) (*ecdsa.PrivateKey, error)"},
		{"ParseOID", Func, 23, "func(oid string) (OID, error)"},
		{"ParsePKCS1PrivateKey", Func, 0, "func(der []byte) (*rsa.PrivateKey, error)"},
		{"ParsePKCS1PublicKey", Func, 10, "func(der []byte) (*rsa.PublicKey, error)"},
		{"ParsePKCS8PrivateKey", Func, 0, "func(der []byte) (key any, err error)"},
		{"ParsePKIXPublicKey", Func, 0, "func(derBytes []byte) (pub any, err error)"},
		{"ParseRevocationList", Func, 19, "func(der []byte) (*RevocationList, error)"},
		{"PolicyMapping", Type, 24, ""},
		{"PolicyMapping.IssuerDomainPolicy", Field, 24, ""},
		{"PolicyMapping.SubjectDomainPolicy", Field, 24, ""},
		{"PublicKeyAlgorithm", Type, 0, ""},
		{"PureEd25519", Const, 13, ""},
		{"RSA", Const, 0, ""},
		{"RevocationList", Type, 15, ""},
		{"RevocationList.AuthorityKeyId", Field, 19, ""},
		{"RevocationList.Extensions", Field, 19, ""},
		{"RevocationList.ExtraExtensions", Field, 15, ""},
		{"RevocationList.Issuer", Field, 19, ""},
		{"RevocationList.NextUpdate", Field, 15, ""},
		{"RevocationList.Number", Field, 15, ""},
		{"RevocationList.Raw", Field, 19, ""},
		{"RevocationList.RawIssuer", Field, 19, ""},
		{"RevocationList.RawTBSRevocationList", Field, 19, ""},
		{"RevocationList.RevokedCertificateEntries", Field, 21, ""},
		{"RevocationList.RevokedCertificates", Field, 15, ""},
		{"RevocationList.Signature", Field, 19, ""},
		{"RevocationList.SignatureAlgorithm", Field, 15, ""},
		{"RevocationList.ThisUpdate", Field, 15, ""},
		{"RevocationListEntry", Type, 21, ""},
		{"RevocationListEntry.Extensions", Field, 21, ""},
		{"RevocationListEntry.ExtraExtensions", Field, 21, ""},
		{"RevocationListEntry.Raw", Field, 21, ""},
		{"RevocationListEntry.ReasonCode", Field, 21, ""},
		{"RevocationListEntry.RevocationTime", Field, 21, ""},
		{"RevocationListEntry.SerialNumber", Field, 21, ""},
		{"SHA1WithRSA", Const, 0, ""},
		{"SHA256WithRSA", Const, 0, ""},
		{"SHA256WithRSAPSS", Const, 8, ""},
		{"SHA384WithRSA", Const, 0, ""},
		{"SHA384WithRSAPSS", Const, 8, ""},
		{"SHA512WithRSA", Const, 0, ""},
		{"SHA512WithRSAPSS", Const, 8, ""},
		{"SetFallbackRoots", Func, 20, "func(roots *CertPool)"},
		{"SignatureAlgorithm", Type, 0, ""},
		{"SystemCertPool", Func, 7, "func() (*CertPool, error)"},
		{"SystemRootsError", Type, 1, ""},
		{"SystemRootsError.Err", Field, 7, ""},
		{"TooManyConstraints", Const, 10, ""},
		{"TooManyIntermediates", Const, 0, ""},
		{"UnconstrainedName", Const, 10, ""},
		{"UnhandledCriticalExtension", Type, 0, ""},
		{"UnknownAuthorityError", Type, 0, ""},
		{"UnknownAuthorityError.Cert", Field, 8, ""},
		{"UnknownPublicKeyAlgorithm", Const, 0, ""},
		{"UnknownSignatureAlgorithm", Const, 0, ""},
		{"VerifyOptions", Type, 0, ""},
		{"VerifyOptions.CertificatePolicies", Field, 24, ""},
		{"VerifyOptions.CurrentTime", Field, 0, ""},
		{"VerifyOptions.DNSName", Field, 0, ""},
		{"VerifyOptions.Intermediates", Field, 0, ""},
		{"VerifyOptions.KeyUsages", Field, 1, ""},
		{"VerifyOptions.MaxConstraintComparisions", Field, 10, ""},
		{"VerifyOptions.Roots", Field, 0, ""},
	},
	"crypto/x509/pkix": {
		{"(*CertificateList).HasExpired", Method, 0, ""},
		{"(*Name).FillFromRDNSequence", Method, 0, ""},
		{"(Name).String", Method, 10, ""},
		{"(Name).ToRDNSequence", Method, 0, ""},
		{"(RDNSequence).String", Method, 10, ""},
		{"AlgorithmIdentifier", Type, 0, ""},
		{"AlgorithmIdentifier.Algorithm", Field, 0, ""},
		{"AlgorithmIdentifier.Parameters", Field, 0, ""},
		{"AttributeTypeAndValue", Type, 0, ""},
		{"AttributeTypeAndValue.Type", Field, 0, ""},
		{"AttributeTypeAndValue.Value", Field, 0, ""},
		{"AttributeTypeAndValueSET", Type, 3, ""},
		{"AttributeTypeAndValueSET.Type", Field, 3, ""},
		{"AttributeTypeAndValueSET.Value", Field, 3, ""},
		{"CertificateList", Type, 0, ""},
		{"CertificateList.SignatureAlgorithm", Field, 0, ""},
		{"CertificateList.SignatureValue", Field, 0, ""},
		{"CertificateList.TBSCertList", Field, 0, ""},
		{"Extension", Type, 0, ""},
		{"Extension.Critical", Field, 0, ""},
		{"Extension.Id", Field, 0, ""},
		{"Extension.Value", Field, 0, ""},
		{"Name", Type, 0, ""},
		{"Name.CommonName", Field, 0, ""},
		{"Name.Country", Field, 0, ""},
		{"Name.ExtraNames", Field, 5, ""},
		{"Name.Locality", Field, 0, ""},
		{"Name.Names", Field, 0, ""},
		{"Name.Organization", Field, 0, ""},
		{"Name.OrganizationalUnit", Field, 0, ""},
		{"Name.PostalCode", Field, 0, ""},
		{"Name.Province", Field, 0, ""},
		{"Name.SerialNumber", Field, 0, ""},
		{"Name.StreetAddress", Field, 0, ""},
		{"RDNSequence", Type, 0, ""},
		{"RelativeDistinguishedNameSET", Type, 0, ""},
		{"RevokedCertificate", Type, 0, ""},
		{"RevokedCertificate.Extensions", Field, 0, ""},
		{"RevokedCertificate.RevocationTime", Field, 0, ""},
		{"RevokedCertificate.SerialNumber", Field, 0, ""},
		{"TBSCertificateList", Type, 0, ""},
		{"TBSCertificateList.Extensions", Field, 0, ""},
		{"TBSCertificateList.Issuer", Field, 0, ""},
		{"TBSCertificateList.NextUpdate", Field, 0, ""},
		{"TBSCertificateList.Raw", Field, 0, ""},
		{"TBSCertificateList.RevokedCertificates", Field, 0, ""},
		{"TBSCertificateList.Signature", Field, 0, ""},
		{"TBSCertificateList.ThisUpdate", Field, 0, ""},
		{"TBSCertificateList.Version", Field, 0, ""},
	},
	"database/sql": {
		{"(*ColumnType).DatabaseTypeName", Method, 8, ""},
		{"(*ColumnType).DecimalSize", Method, 8, ""},
		{"(*ColumnType).Length", Method, 8, ""},
		{"(*ColumnType).Name", Method, 8, ""},
		{"(*ColumnType).Nullable", Method, 8, ""},
		{"(*ColumnType).ScanType", Method, 8, ""},
		{"(*Conn).BeginTx", Method, 9, ""},
		{"(*Conn).Close", Method, 9, ""},
		{"(*Conn).ExecContext", Method, 9, ""},
		{"(*Conn).PingContext", Method, 9, ""},
		{"(*Conn).PrepareContext", Method, 9, ""},
		{"(*Conn).QueryContext", Method, 9, ""},
		{"(*Conn).QueryRowContext", Method, 9, ""},
		{"(*Conn).Raw", Method, 13, ""},
		{"(*DB).Begin", Method, 0, ""},
		{"(*DB).BeginTx", Method, 8, ""},
		{"(*DB).Close", Method, 0, ""},
		{"(*DB).Conn", Method, 9, ""},
		{"(*DB).Driver", Method, 0, ""},
		{"(*DB).Exec", Method, 0, ""},
		{"(*DB).ExecContext", Method, 8, ""},
		{"(*DB).Ping", Method, 1, ""},
		{"(*DB).PingContext", Method, 8, ""},
		{"(*DB).Prepare", Method, 0, ""},
		{"(*DB).PrepareContext", Method, 8, ""},
		{"(*DB).Query", Method, 0, ""},
		{"(*DB).QueryContext", Method, 8, ""},
		{"(*DB).QueryRow", Method, 0, ""},
		{"(*DB).QueryRowContext", Method, 8, ""},
		{"(*DB).SetConnMaxIdleTime", Method, 15, ""},
		{"(*DB).SetConnMaxLifetime", Method, 6, ""},
		{"(*DB).SetMaxIdleConns", Method, 1, ""},
		{"(*DB).SetMaxOpenConns", Method, 2, ""},
		{"(*DB).Stats", Method, 5, ""},
		{"(*Null).Scan", Method, 22, ""},
		{"(*NullBool).Scan", Method, 0, ""},
		{"(*NullByte).Scan", Method, 17, ""},
		{"(*NullFloat64).Scan", Method, 0, ""},
		{"(*NullInt16).Scan", Method, 17, ""},
		{"(*NullInt32).Scan", Method, 13, ""},
		{"(*NullInt64).Scan", Method, 0, ""},
		{"(*NullString).Scan", Method, 0, ""},
		{"(*NullTime).Scan", Method, 13, ""},
		{"(*Row).Err", Method, 15, ""},
		{"(*Row).Scan", Method, 0, ""},
		{"(*Rows).Close", Method, 0, ""},
		{"(*Rows).ColumnTypes", Method, 8, ""},
		{"(*Rows).Columns", Method, 0, ""},
		{"(*Rows).Err", Method, 0, ""},
		{"(*Rows).Next", Method, 0, ""},
		{"(*Rows).NextResultSet", Method, 8, ""},
		{"(*Rows).Scan", Method, 0, ""},
		{"(*Stmt).Close", Method, 0, ""},
		{"(*Stmt).Exec", Method, 0, ""},
		{"(*Stmt).ExecContext", Method, 8, ""},
		{"(*Stmt).Query", Method, 0, ""},
		{"(*Stmt).QueryContext", Method, 8, ""},
		{"(*Stmt).QueryRow", Method, 0, ""},
		{"(*Stmt).QueryRowContext", Method, 8, ""},
		{"(*Tx).Commit", Method, 0, ""},
		{"(*Tx).Exec", Method, 0, ""},
		{"(*Tx).ExecContext", Method, 8, ""},
		{"(*Tx).Prepare", Method, 0, ""},
		{"(*Tx).PrepareContext", Method, 8, ""},
		{"(*Tx).Query", Method, 0, ""},
		{"(*Tx).QueryContext", Method, 8, ""},
		{"(*Tx).QueryRow", Method, 0, ""},
		{"(*Tx).QueryRowContext", Method, 8, ""},
		{"(*Tx).Rollback", Method, 0, ""},
		{"(*Tx).Stmt", Method, 0, ""},
		{"(*Tx).StmtContext", Method, 8, ""},
		{"(IsolationLevel).String", Method, 11, ""},
		{"(Null).Value", Method, 22, ""},
		{"(NullBool).Value", Method, 0, ""},
		{"(NullByte).Value", Method, 17, ""},
		{"(NullFloat64).Value", Method, 0, ""},
		{"(NullInt16).Value", Method, 17, ""},
		{"(NullInt32).Value", Method, 13, ""},
		{"(NullInt64).Value", Method, 0, ""},
		{"(NullString).Value", Method, 0, ""},
		{"(NullTime).Value", Method, 13, ""},
		{"(Result).LastInsertId", Method, 0, ""},
		{"(Result).RowsAffected", Method, 0, ""},
		{"(Scanner).Scan", Method, 0, ""},
		{"ColumnType", Type, 8, ""},
		{"Conn", Type, 9, ""},
		{"DB", Type, 0, ""},
		{"DBStats", Type, 5, ""},
		{"DBStats.Idle", Field, 11, ""},
		{"DBStats.InUse", Field, 11, ""},
		{"DBStats.MaxIdleClosed", Field, 11, ""},
		{"DBStats.MaxIdleTimeClosed", Field, 15, ""},
		{"DBStats.MaxLifetimeClosed", Field, 11, ""},
		{"DBStats.MaxOpenConnections", Field, 11, ""},
		{"DBStats.OpenConnections", Field, 5, ""},
		{"DBStats.WaitCount", Field, 11, ""},
		{"DBStats.WaitDuration", Field, 11, ""},
		{"Drivers", Func, 4, "func() []string"},
		{"ErrConnDone", Var, 9, ""},
		{"ErrNoRows", Var, 0, ""},
		{"ErrTxDone", Var, 0, ""},
		{"IsolationLevel", Type, 8, ""},
		{"LevelDefault", Const, 8, ""},
		{"LevelLinearizable", Const, 8, ""},
		{"LevelReadCommitted", Const, 8, ""},
		{"LevelReadUncommitted", Const, 8, ""},
		{"LevelRepeatableRead", Const, 8, ""},
		{"LevelSerializable", Const, 8, ""},
		{"LevelSnapshot", Const, 8, ""},
		{"LevelWriteCommitted", Const, 8, ""},
		{"Named", Func, 8, "func(name string, value any) NamedArg"},
		{"NamedArg", Type, 8, ""},
		{"NamedArg.Name", Field, 8, ""},
		{"NamedArg.Value", Field, 8, ""},
		{"Null", Type, 22, ""},
		{"NullBool", Type, 0, ""},
		{"NullBool.Bool", Field, 0, ""},
		{"NullBool.Valid", Field, 0, ""},
		{"NullByte", Type, 17, ""},
		{"NullByte.Byte", Field, 17, ""},
		{"NullByte.Valid", Field, 17, ""},
		{"NullFloat64", Type, 0, ""},
		{"NullFloat64.Float64", Field, 0, ""},
		{"NullFloat64.Valid", Field, 0, ""},
		{"NullInt16", Type, 17, ""},
		{"NullInt16.Int16", Field, 17, ""},
		{"NullInt16.Valid", Field, 17, ""},
		{"NullInt32", Type, 13, ""},
		{"NullInt32.Int32", Field, 13, ""},
		{"NullInt32.Valid", Field, 13, ""},
		{"NullInt64", Type, 0, ""},
		{"NullInt64.Int64", Field, 0, ""},
		{"NullInt64.Valid", Field, 0, ""},
		{"NullString", Type, 0, ""},
		{"NullString.String", Field, 0, ""},
		{"NullString.Valid", Field, 0, ""},
		{"NullTime", Type, 13, ""},
		{"NullTime.Time", Field, 13, ""},
		{"NullTime.Valid", Field, 13, ""},
		{"Open", Func, 0, "func(driverName string, dataSourceName string) (*DB, error)"},
		{"OpenDB", Func, 10, "func(c driver.Connector) *DB"},
		{"Out", Type, 9, ""},
		{"Out.Dest", Field, 9, ""},
		{"Out.In", Field, 9, ""},
		{"RawBytes", Type, 0, ""},
		{"Register", Func, 0, "func(name string, driver driver.Driver)"},
		{"Result", Type, 0, ""},
		{"Row", Type, 0, ""},
		{"Rows", Type, 0, ""},
		{"Scanner", Type, 0, ""},
		{"Stmt", Type, 0, ""},
		{"Tx", Type, 0, ""},
		{"TxOptions", Type, 8, ""},
		{"TxOptions.Isolation", Field, 8, ""},
		{"TxOptions.ReadOnly", Field, 8, ""},
	},
	"database/sql/driver": {
		{"(ColumnConverter).ColumnConverter", Method, 0, ""},
		{"(Conn).Begin", Method, 0, ""},
		{"(Conn).Close", Method, 0, ""},
		{"(Conn).Prepare", Method, 0, ""},
		{"(ConnBeginTx).BeginTx", Method, 8, ""},
		{"(ConnPrepareContext).PrepareContext", Method, 8, ""},
		{"(Connector).Connect", Method, 10, ""},
		{"(Connector).Driver", Method, 10, ""},
		{"(Driver).Open", Method, 0, ""},
		{"(DriverContext).OpenConnector", Method, 10, ""},
		{"(Execer).Exec", Method, 0, ""},
		{"(ExecerContext).ExecContext", Method, 8, ""},
		{"(NamedValueChecker).CheckNamedValue", Method, 9, ""},
		{"(NotNull).ConvertValue", Method, 0, ""},
		{"(Null).ConvertValue", Method, 0, ""},
		{"(Pinger).Ping", Method, 8, ""},
		{"(Queryer).Query", Method, 1, ""},
		{"(QueryerContext).QueryContext", Method, 8, ""},
		{"(Result).LastInsertId", Method, 0, ""},
		{"(Result).RowsAffected", Method, 0, ""},
		{"(Rows).Close", Method, 0, ""},
		{"(Rows).Columns", Method, 0, ""},
		{"(Rows).Next", Method, 0, ""},
		{"(RowsAffected).LastInsertId", Method, 0, ""},
		{"(RowsAffected).RowsAffected", Method, 0, ""},
		{"(RowsColumnTypeDatabaseTypeName).Close", Method, 8, ""},
		{"(RowsColumnTypeDatabaseTypeName).ColumnTypeDatabaseTypeName", Method, 8, ""},
		{"(RowsColumnTypeDatabaseTypeName).Columns", Method, 8, ""},
		{"(RowsColumnTypeDatabaseTypeName).Next", Method, 8, ""},
		{"(RowsColumnTypeLength).Close", Method, 8, ""},
		{"(RowsColumnTypeLength).ColumnTypeLength", Method, 8, ""},
		{"(RowsColumnTypeLength).Columns", Method, 8, ""},
		{"(RowsColumnTypeLength).Next", Method, 8, ""},
		{"(RowsColumnTypeNullable).Close", Method, 8, ""},
		{"(RowsColumnTypeNullable).ColumnTypeNullable", Method, 8, ""},
		{"(RowsColumnTypeNullable).Columns", Method, 8, ""},
		{"(RowsColumnTypeNullable).Next", Method, 8, ""},
		{"(RowsColumnTypePrecisionScale).Close", Method, 8, ""},
		{"(RowsColumnTypePrecisionScale).ColumnTypePrecisionScale", Method, 8, ""},
		{"(RowsColumnTypePrecisionScale).Columns", Method, 8, ""},
		{"(RowsColumnTypePrecisionScale).Next", Method, 8, ""},
		{"(RowsColumnTypeScanType).Close", Method, 8, ""},
		{"(RowsColumnTypeScanType).ColumnTypeScanType", Method, 8, ""},
		{"(RowsColumnTypeScanType).Columns", Method, 8, ""},
		{"(RowsColumnTypeScanType).Next", Method, 8, ""},
		{"(RowsNextResultSet).Close", Method, 8, ""},
		{"(RowsNextResultSet).Columns", Method, 8, ""},
		{"(RowsNextResultSet).HasNextResultSet", Method, 8, ""},
		{"(RowsNextResultSet).Next", Method, 8, ""},
		{"(RowsNextResultSet).NextResultSet", Method, 8, ""},
		{"(SessionResetter).ResetSession", Method, 10, ""},
		{"(Stmt).Close", Method, 0, ""},
		{"(Stmt).Exec", Method, 0, ""},
		{"(Stmt).NumInput", Method, 0, ""},
		{"(Stmt).Query", Method, 0, ""},
		{"(StmtExecContext).ExecContext", Method, 8, ""},
		{"(StmtQueryContext).QueryContext", Method, 8, ""},
		{"(Tx).Commit", Method, 0, ""},
		{"(Tx).Rollback", Method, 0, ""},
		{"(Validator).IsValid", Method, 15, ""},
		{"(ValueConverter).ConvertValue", Method, 0, ""},
		{"(Valuer).Value", Method, 0, ""},
		{"Bool", Var, 0, ""},
		{"ColumnConverter", Type, 0, ""},
		{"Conn", Type, 0, ""},
		{"ConnBeginTx", Type, 8, ""},
		{"ConnPrepareContext", Type, 8, ""},
		{"Connector", Type, 10, ""},
		{"DefaultParameterConverter", Var, 0, ""},
		{"Driver", Type, 0, ""},
		{"DriverContext", Type, 10, ""},
		{"ErrBadConn", Var, 0, ""},
		{"ErrRemoveArgument", Var, 9, ""},
		{"ErrSkip", Var, 0, ""},
		{"Execer", Type, 0, ""},
		{"ExecerContext", Type, 8, ""},
		{"Int32", Var, 0, ""},
		{"IsScanValue", Func, 0, "func(v any) bool"},
		{"IsValue", Func, 0, "func(v any) bool"},
		{"IsolationLevel", Type, 8, ""},
		{"NamedValue", Type, 8, ""},
		{"NamedValue.Name", Field, 8, ""},
		{"NamedValue.Ordinal", Field, 8, ""},
		{"NamedValue.Value", Field, 8, ""},
		{"NamedValueChecker", Type, 9, ""},
		{"NotNull", Type, 0, ""},
		{"NotNull.Converter", Field, 0, ""},
		{"Null", Type, 0, ""},
		{"Null.Converter", Field, 0, ""},
		{"Pinger", Type, 8, ""},
		{"Queryer", Type, 1, ""},
		{"QueryerContext", Type, 8, ""},
		{"Result", Type, 0, ""},
		{"ResultNoRows", Var, 0, ""},
		{"Rows", Type, 0, ""},
		{"RowsAffected", Type, 0, ""},
		{"RowsColumnTypeDatabaseTypeName", Type, 8, ""},
		{"RowsColumnTypeLength", Type, 8, ""},
		{"RowsColumnTypeNullable", Type, 8, ""},
		{"RowsColumnTypePrecisionScale", Type, 8, ""},
		{"RowsColumnTypeScanType", Type, 8, ""},
		{"RowsNextResultSet", Type, 8, ""},
		{"SessionResetter", Type, 10, ""},
		{"Stmt", Type, 0, ""},
		{"StmtExecContext", Type, 8, ""},
		{"StmtQueryContext", Type, 8, ""},
		{"String", Var, 0, ""},
		{"Tx", Type, 0, ""},
		{"TxOptions", Type, 8, ""},
		{"TxOptions.Isolation", Field, 8, ""},
		{"TxOptions.ReadOnly", Field, 8, ""},
		{"Validator", Type, 15, ""},
		{"Value", Type, 0, ""},
		{"ValueConverter", Type, 0, ""},
		{"Valuer", Type, 0, ""},
	},
	"debug/buildinfo": {
		{"BuildInfo", Type, 18, ""},
		{"Read", Func, 18, "func(r io.ReaderAt) (*BuildInfo, error)"},
		{"ReadFile", Func, 18, "func(name string) (info *BuildInfo, err error)"},
	},
	"debug/dwarf": {
		{"(*AddrType).Basic", Method, 0, ""},
		{"(*AddrType).Common", Method, 0, ""},
		{"(*AddrType).Size", Method, 0, ""},
		{"(*AddrType).String", Method, 0, ""},
		{"(*ArrayType).Common", Method, 0, ""},
		{"(*ArrayType).Size", Method, 0, ""},
		{"(*ArrayType).String", Method, 0, ""},
		{"(*BasicType).Basic", Method, 0, ""},
		{"(*BasicType).Common", Method, 0, ""},
		{"(*BasicType).Size", Method, 0, ""},
		{"(*BasicType).String", Method, 0, ""},
		{"(*BoolType).Basic", Method, 0, ""},
		{"(*BoolType).Common", Method, 0, ""},
		{"(*BoolType).Size", Method, 0, ""},
		{"(*BoolType).String", Method, 0, ""},
		{"(*CharType).Basic", Method, 0, ""},
		{"(*CharType).Common", Method, 0, ""},
		{"(*CharType).Size", Method, 0, ""},
		{"(*CharType).String", Method, 0, ""},
		{"(*CommonType).Common", Method, 0, ""},
		{"(*CommonType).Size", Method, 0, ""},
		{"(*ComplexType).Basic", Method, 0, ""},
		{"(*ComplexType).Common", Method, 0, ""},
		{"(*ComplexType).Size", Method, 0, ""},
		{"(*ComplexType).String", Method, 0, ""},
		{"(*Data).AddSection", Method, 14, ""},
		{"(*Data).AddTypes", Method, 3, ""},
		{"(*Data).LineReader", Method, 5, ""},
		{"(*Data).Ranges", Method, 7, ""},
		{"(*Data).Reader", Method, 0, ""},
		{"(*Data).Type", Method, 0, ""},
		{"(*DotDotDotType).Common", Method, 0, ""},
		{"(*DotDotDotType).Size", Method, 0, ""},
		{"(*DotDotDotType).String", Method, 0, ""},
		{"(*Entry).AttrField", Method, 5, ""},
		{"(*Entry).Val", Method, 0, ""},
		{"(*EnumType).Common", Method, 0, ""},
		{"(*EnumType).Size", Method, 0, ""},
		{"(*EnumType).String", Method, 0, ""},
		{"(*FloatType).Basic", Method, 0, ""},
		{"(*FloatType).Common", Method, 0, ""},
		{"(*FloatType).Size", Method, 0, ""},
		{"(*FloatType).String", Method, 0, ""},
		{"(*FuncType).Common", Method, 0, ""},
		{"(*FuncType).Size", Method, 0, ""},
		{"(*FuncType).String", Method, 0, ""},
		{"(*IntType).Basic", Method, 0, ""},
		{"(*IntType).Common", Method, 0, ""},
		{"(*IntType).Size", Method, 0, ""},
		{"(*IntType).String", Method, 0, ""},
		{"(*LineReader).Files", Method, 14, ""},
		{"(*LineReader).Next", Method, 5, ""},
		{"(*LineReader).Reset", Method, 5, ""},
		{"(*LineReader).Seek", Method, 5, ""},
		{"(*LineReader).SeekPC", Method, 5, ""},
		{"(*LineReader).Tell", Method, 5, ""},
		{"(*PtrType).Common", Method, 0, ""},
		{"(*PtrType).Size", Method, 0, ""},
		{"(*PtrType).String", Method, 0, ""},
		{"(*QualType).Common", Method, 0, ""},
		{"(*QualType).Size", Method, 0, ""},
		{"(*QualType).String", Method, 0, ""},
		{"(*Reader).AddressSize", Method, 5, ""},
		{"(*Reader).ByteOrder", Method, 14, ""},
		{"(*Reader).Next", Method, 0, ""},
		{"(*Reader).Seek", Method, 0, ""},
		{"(*Reader).SeekPC", Method, 7, ""},
		{"(*Reader).SkipChildren", Method, 0, ""},
		{"(*StructType).Common", Method, 0, ""},
		{"(*StructType).Defn", Method, 0, ""},
		{"(*StructType).Size", Method, 0, ""},
		{"(*StructType).String", Method, 0, ""},
		{"(*TypedefType).Common", Method, 0, ""},
		{"(*TypedefType).Size", Method, 0, ""},
		{"(*TypedefType).String", Method, 0, ""},
		{"(*UcharType).Basic", Method, 0, ""},
		{"(*UcharType).Common", Method, 0, ""},
		{"(*UcharType).Size", Method, 0, ""},
		{"(*UcharType).String", Method, 0, ""},
		{"(*UintType).Basic", Method, 0, ""},
		{"(*UintType).Common", Method, 0, ""},
		{"(*UintType).Size", Method, 0, ""},
		{"(*UintType).String", Method, 0, ""},
		{"(*UnspecifiedType).Basic", Method, 4, ""},
		{"(*UnspecifiedType).Common", Method, 4, ""},
		{"(*UnspecifiedType).Size", Method, 4, ""},
		{"(*UnspecifiedType).String", Method, 4, ""},
		{"(*UnsupportedType).Common", Method, 13, ""},
		{"(*UnsupportedType).Size", Method, 13, ""},
		{"(*UnsupportedType).String", Method, 13, ""},
		{"(*VoidType).Common", Method, 0, ""},
		{"(*VoidType).Size", Method, 0, ""},
		{"(*VoidType).String", Method, 0, ""},
		{"(Attr).GoString", Method, 0, ""},
		{"(Attr).String", Method, 0, ""},
		{"(Class).GoString", Method, 5, ""},
		{"(Class).String", Method, 5, ""},
		{"(DecodeError).Error", Method, 0, ""},
		{"(Tag).GoString", Method, 0, ""},
		{"(Tag).String", Method, 0, ""},
		{"(Type).Common", Method, 0, ""},
		{"(Type).Size", Method, 0, ""},
		{"(Type).String", Method, 0, ""},
		{"AddrType", Type, 0, ""},
		{"AddrType.BasicType", Field, 0, ""},
		{"ArrayType", Type, 0, ""},
		{"ArrayType.CommonType", Field, 0, ""},
		{"ArrayType.Count", Field, 0, ""},
		{"ArrayType.StrideBitSize", Field, 0, ""},
		{"ArrayType.Type", Field, 0, ""},
		{"Attr", Type, 0, ""},
		{"AttrAbstractOrigin", Const, 0, ""},
		{"AttrAccessibility", Const, 0, ""},
		{"AttrAddrBase", Const, 14, ""},
		{"AttrAddrClass", Const, 0, ""},
		{"AttrAlignment", Const, 14, ""},
		{"AttrAllocated", Const, 0, ""},
		{"AttrArtificial", Const, 0, ""},
		{"AttrAssociated", Const, 0, ""},
		{"AttrBaseTypes", Const, 0, ""},
		{"AttrBinaryScale", Const, 14, ""},
		{"AttrBitOffset", Const, 0, ""},
		{"AttrBitSize", Const, 0, ""},
		{"AttrByteSize", Const, 0, ""},
		{"AttrCallAllCalls", Const, 14, ""},
		{"AttrCallAllSourceCalls", Const, 14, ""},
		{"AttrCallAllTailCalls", Const, 14, ""},
		{"AttrCallColumn", Const, 0, ""},
		{"AttrCallDataLocation", Const, 14, ""},
		{"AttrCallDataValue", Const, 14, ""},
		{"AttrCallFile", Const, 0, ""},
		{"AttrCallLine", Const, 0, ""},
		{"AttrCallOrigin", Const, 14, ""},
		{"AttrCallPC", Const, 14, ""},
		{"AttrCallParameter", Const, 14, ""},
		{"AttrCallReturnPC", Const, 14, ""},
		{"AttrCallTailCall", Const, 14, ""},
		{"AttrCallTarget", Const, 14, ""},
		{"AttrCallTargetClobbered", Const, 14, ""},
		{"AttrCallValue", Const, 14, ""},
		{"AttrCalling", Const, 0, ""},
		{"AttrCommonRef", Const, 0, ""},
		{"AttrCompDir", Const, 0, ""},
		{"AttrConstExpr", Const, 14, ""},
		{"AttrConstValue", Const, 0, ""},
		{"AttrContainingType", Const, 0, ""},
		{"AttrCount", Const, 0, ""},
		{"AttrDataBitOffset", Const, 14, ""},
		{"AttrDataLocation", Const, 0, ""},
		{"AttrDataMemberLoc", Const, 0, ""},
		{"AttrDecimalScale", Const, 14, ""},
		{"AttrDecimalSign", Const, 14, ""},
		{"AttrDeclColumn", Const, 0, ""},
		{"AttrDeclFile", Const, 0, ""},
		{"AttrDeclLine", Const, 0, ""},
		{"AttrDeclaration", Const, 0, ""},
		{"AttrDefaultValue", Const, 0, ""},
		{"AttrDefaulted", Const, 14, ""},
		{"AttrDeleted", Const, 14, ""},
		{"AttrDescription", Const, 0, ""},
		{"AttrDigitCount", Const, 14, ""},
		{"AttrDiscr", Const, 0, ""},
		{"AttrDiscrList", Const, 0, ""},
		{"AttrDiscrValue", Const, 0, ""},
		{"AttrDwoName", Const, 14, ""},
		{"AttrElemental", Const, 14, ""},
		{"AttrEncoding", Const, 0, ""},
		{"AttrEndianity", Const, 14, ""},
		{"AttrEntrypc", Const, 0, ""},
		{"AttrEnumClass", Const, 14, ""},
		{"AttrExplicit", Const, 14, ""},
		{"AttrExportSymbols", Const, 14, ""},
		{"AttrExtension", Const, 0, ""},
		{"AttrExternal", Const, 0, ""},
		{"AttrFrameBase", Const, 0, ""},
		{"AttrFriend", Const, 0, ""},
		{"AttrHighpc", Const, 0, ""},
		{"AttrIdentifierCase", Const, 0, ""},
		{"AttrImport", Const, 0, ""},
		{"AttrInline", Const, 0, ""},
		{"AttrIsOptional", Const, 0, ""},
		{"AttrLanguage", Const, 0, ""},
		{"AttrLinkageName", Const, 14, ""},
		{"AttrLocation", Const, 0, ""},
		{"AttrLoclistsBase", Const, 14, ""},
		{"AttrLowerBound", Const, 0, ""},
		{"AttrLowpc", Const, 0, ""},
		{"AttrMacroInfo", Const, 0, ""},
		{"AttrMacros", Const, 14, ""},
		{"AttrMainSubprogram", Const, 14, ""},
		{"AttrMutable", Const, 14, ""},
		{"AttrName", Const, 0, ""},
		{"AttrNamelistItem", Const, 0, ""},
		{"AttrNoreturn", Const, 14, ""},
		{"AttrObjectPointer", Const, 14, ""},
		{"AttrOrdering", Const, 0, ""},
		{"AttrPictureString", Const, 14, ""},
		{"AttrPriority", Const, 0, ""},
		{"AttrProducer", Const, 0, ""},
		{"AttrPrototyped", Const, 0, ""},
		{"AttrPure", Const, 14, ""},
		{"AttrRanges", Const, 0, ""},
		{"AttrRank", Const, 14, ""},
		{"AttrRecursive", Const, 14, ""},
		{"AttrReference", Const, 14, ""},
		{"AttrReturnAddr", Const, 0, ""},
		{"AttrRnglistsBase", Const, 14, ""},
		{"AttrRvalueReference", Const, 14, ""},
		{"AttrSegment", Const, 0, ""},
		{"AttrSibling", Const, 0, ""},
		{"AttrSignature", Const, 14, ""},
		{"AttrSmall", Const, 14, ""},
		{"AttrSpecification", Const, 0, ""},
		{"AttrStartScope", Const, 0, ""},
		{"AttrStaticLink", Const, 0, ""},
		{"AttrStmtList", Const, 0, ""},
		{"AttrStrOffsetsBase", Const, 14, ""},
		{"AttrStride", Const, 0, ""},
		{"AttrStrideSize", Const, 0, ""},
		{"AttrStringLength", Const, 0, ""},
		{"AttrStringLengthBitSize", Const, 14, ""},
		{"AttrStringLengthByteSize", Const, 14, ""},
		{"AttrThreadsScaled", Const, 14, ""},
		{"AttrTrampoline", Const, 0, ""},
		{"AttrType", Const, 0, ""},
		{"AttrUpperBound", Const, 0, ""},
		{"AttrUseLocation", Const, 0, ""},
		{"AttrUseUTF8", Const, 0, ""},
		{"AttrVarParam", Const, 0, ""},
		{"AttrVirtuality", Const, 0, ""},
		{"AttrVisibility", Const, 0, ""},
		{"AttrVtableElemLoc", Const, 0, ""},
		{"BasicType", Type, 0, ""},
		{"BasicType.BitOffset", Field, 0, ""},
		{"BasicType.BitSize", Field, 0, ""},
		{"BasicType.CommonType", Field, 0, ""},
		{"BasicType.DataBitOffset", Field, 18, ""},
		{"BoolType", Type, 0, ""},
		{"BoolType.BasicType", Field, 0, ""},
		{"CharType", Type, 0, ""},
		{"CharType.BasicType", Field, 0, ""},
		{"Class", Type, 5, ""},
		{"ClassAddrPtr", Const, 14, ""},
		{"ClassAddress", Const, 5, ""},
		{"ClassBlock", Const, 5, ""},
		{"ClassConstant", Const, 5, ""},
		{"ClassExprLoc", Const, 5, ""},
		{"ClassFlag", Const, 5, ""},
		{"ClassLinePtr", Const, 5, ""},
		{"ClassLocList", Const, 14, ""},
		{"ClassLocListPtr", Const, 5, ""},
		{"ClassMacPtr", Const, 5, ""},
		{"ClassRangeListPtr", Const, 5, ""},
		{"ClassReference", Const, 5, ""},
		{"ClassReferenceAlt", Const, 5, ""},
		{"ClassReferenceSig", Const, 5, ""},
		{"ClassRngList", Const, 14, ""},
		{"ClassRngListsPtr", Const, 14, ""},
		{"ClassStrOffsetsPtr", Const, 14, ""},
		{"ClassString", Const, 5, ""},
		{"ClassStringAlt", Const, 5, ""},
		{"ClassUnknown", Const, 6, ""},
		{"CommonType", Type, 0, ""},
		{"CommonType.ByteSize", Field, 0, ""},
		{"CommonType.Name", Field, 0, ""},
		{"ComplexType", Type, 0, ""},
		{"ComplexType.BasicType", Field, 0, ""},
		{"Data", Type, 0, ""},
		{"DecodeError", Type, 0, ""},
		{"DecodeError.Err", Field, 0, ""},
		{"DecodeError.Name", Field, 0, ""},
		{"DecodeError.Offset", Field, 0, ""},
		{"DotDotDotType", Type, 0, ""},
		{"DotDotDotType.CommonType", Field, 0, ""},
		{"Entry", Type, 0, ""},
		{"Entry.Children", Field, 0, ""},
		{"Entry.Field", Field, 0, ""},
		{"Entry.Offset", Field, 0, ""},
		{"Entry.Tag", Field, 0, ""},
		{"EnumType", Type, 0, ""},
		{"EnumType.CommonType", Field, 0, ""},
		{"EnumType.EnumName", Field, 0, ""},
		{"EnumType.Val", Field, 0, ""},
		{"EnumValue", Type, 0, ""},
		{"EnumValue.Name", Field, 0, ""},
		{"EnumValue.Val", Field, 0, ""},
		{"ErrUnknownPC", Var, 5, ""},
		{"Field", Type, 0, ""},
		{"Field.Attr", Field, 0, ""},
		{"Field.Class", Field, 5, ""},
		{"Field.Val", Field, 0, ""},
		{"FloatType", Type, 0, ""},
		{"FloatType.BasicType", Field, 0, ""},
		{"FuncType", Type, 0, ""},
		{"FuncType.CommonType", Field, 0, ""},
		{"FuncType.ParamType", Field, 0, ""},
		{"FuncType.ReturnType", Field, 0, ""},
		{"IntType", Type, 0, ""},
		{"IntType.BasicType", Field, 0, ""},
		{"LineEntry", Type, 5, ""},
		{"LineEntry.Address", Field, 5, ""},
		{"LineEntry.BasicBlock", Field, 5, ""},
		{"LineEntry.Column", Field, 5, ""},
		{"LineEntry.Discriminator", Field, 5, ""},
		{"LineEntry.EndSequence", Field, 5, ""},
		{"LineEntry.EpilogueBegin", Field, 5, ""},
		{"LineEntry.File", Field, 5, ""},
		{"LineEntry.ISA", Field, 5, ""},
		{"LineEntry.IsStmt", Field, 5, ""},
		{"LineEntry.Line", Field, 5, ""},
		{"LineEntry.OpIndex", Field, 5, ""},
		{"LineEntry.PrologueEnd", Field, 5, ""},
		{"LineFile", Type, 5, ""},
		{"LineFile.Length", Field, 5, ""},
		{"LineFile.Mtime", Field, 5, ""},
		{"LineFile.Name", Field, 5, ""},
		{"LineReader", Type, 5, ""},
		{"LineReaderPos", Type, 5, ""},
		{"New", Func, 0, "func(abbrev []byte, aranges []byte, frame []byte, info []byte, line []byte, pubnames []byte, ranges []byte, str []byte) (*Data, error)"},
		{"Offset", Type, 0, ""},
		{"PtrType", Type, 0, ""},
		{"PtrType.CommonType", Field, 0, ""},
		{"PtrType.Type", Field, 0, ""},
		{"QualType", Type, 0, ""},
		{"QualType.CommonType", Field, 0, ""},
		{"QualType.Qual", Field, 0, ""},
		{"QualType.Type", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"StructField", Type, 0, ""},
		{"StructField.BitOffset", Field, 0, ""},
		{"StructField.BitSize", Field, 0, ""},
		{"StructField.ByteOffset", Field, 0, ""},
		{"StructField.ByteSize", Field, 0, ""},
		{"StructField.DataBitOffset", Field, 18, ""},
		{"StructField.Name", Field, 0, ""},
		{"StructField.Type", Field, 0, ""},
		{"StructType", Type, 0, ""},
		{"StructType.CommonType", Field, 0, ""},
		{"StructType.Field", Field, 0, ""},
		{"StructType.Incomplete", Field, 0, ""},
		{"StructType.Kind", Field, 0, ""},
		{"StructType.StructName", Field, 0, ""},
		{"Tag", Type, 0, ""},
		{"TagAccessDeclaration", Const, 0, ""},
		{"TagArrayType", Const, 0, ""},
		{"TagAtomicType", Const, 14, ""},
		{"TagBaseType", Const, 0, ""},
		{"TagCallSite", Const, 14, ""},
		{"TagCallSiteParameter", Const, 14, ""},
		{"TagCatchDwarfBlock", Const, 0, ""},
		{"TagClassType", Const, 0, ""},
		{"TagCoarrayType", Const, 14, ""},
		{"TagCommonDwarfBlock", Const, 0, ""},
		{"TagCommonInclusion", Const, 0, ""},
		{"TagCompileUnit", Const, 0, ""},
		{"TagCondition", Const, 3, ""},
		{"TagConstType", Const, 0, ""},
		{"TagConstant", Const, 0, ""},
		{"TagDwarfProcedure", Const, 0, ""},
		{"TagDynamicType", Const, 14, ""},
		{"TagEntryPoint", Const, 0, ""},
		{"TagEnumerationType", Const, 0, ""},
		{"TagEnumerator", Const, 0, ""},
		{"TagFileType", Const, 0, ""},
		{"TagFormalParameter", Const, 0, ""},
		{"TagFriend", Const, 0, ""},
		{"TagGenericSubrange", Const, 14, ""},
		{"TagImmutableType", Const, 14, ""},
		{"TagImportedDeclaration", Const, 0, ""},
		{"TagImportedModule", Const, 0, ""},
		{"TagImportedUnit", Const, 0, ""},
		{"TagInheritance", Const, 0, ""},
		{"TagInlinedSubroutine", Const, 0, ""},
		{"TagInterfaceType", Const, 0, ""},
		{"TagLabel", Const, 0, ""},
		{"TagLexDwarfBlock", Const, 0, ""},
		{"TagMember", Const, 0, ""},
		{"TagModule", Const, 0, ""},
		{"TagMutableType", Const, 0, ""},
		{"TagNamelist", Const, 0, ""},
		{"TagNamelistItem", Const, 0, ""},
		{"TagNamespace", Const, 0, ""},
		{"TagPackedType", Const, 0, ""},
		{"TagPartialUnit", Const, 0, ""},
		{"TagPointerType", Const, 0, ""},
		{"TagPtrToMemberType", Const, 0, ""},
		{"TagReferenceType", Const, 0, ""},
		{"TagRestrictType", Const, 0, ""},
		{"TagRvalueReferenceType", Const, 3, ""},
		{"TagSetType", Const, 0, ""},
		{"TagSharedType", Const, 3, ""},
		{"TagSkeletonUnit", Const, 14, ""},
		{"TagStringType", Const, 0, ""},
		{"TagStructType", Const, 0, ""},
		{"TagSubprogram", Const, 0, ""},
		{"TagSubrangeType", Const, 0, ""},
		{"TagSubroutineType", Const, 0, ""},
		{"TagTemplateAlias", Const, 3, ""},
		{"TagTemplateTypeParameter", Const, 0, ""},
		{"TagTemplateValueParameter", Const, 0, ""},
		{"TagThrownType", Const, 0, ""},
		{"TagTryDwarfBlock", Const, 0, ""},
		{"TagTypeUnit", Const, 3, ""},
		{"TagTypedef", Const, 0, ""},
		{"TagUnionType", Const, 0, ""},
		{"TagUnspecifiedParameters", Const, 0, ""},
		{"TagUnspecifiedType", Const, 0, ""},
		{"TagVariable", Const, 0, ""},
		{"TagVariant", Const, 0, ""},
		{"TagVariantPart", Const, 0, ""},
		{"TagVolatileType", Const, 0, ""},
		{"TagWithStmt", Const, 0, ""},
		{"Type", Type, 0, ""},
		{"TypedefType", Type, 0, ""},
		{"TypedefType.CommonType", Field, 0, ""},
		{"TypedefType.Type", Field, 0, ""},
		{"UcharType", Type, 0, ""},
		{"UcharType.BasicType", Field, 0, ""},
		{"UintType", Type, 0, ""},
		{"UintType.BasicType", Field, 0, ""},
		{"UnspecifiedType", Type, 4, ""},
		{"UnspecifiedType.BasicType", Field, 4, ""},
		{"UnsupportedType", Type, 13, ""},
		{"UnsupportedType.CommonType", Field, 13, ""},
		{"UnsupportedType.Tag", Field, 13, ""},
		{"VoidType", Type, 0, ""},
		{"VoidType.CommonType", Field, 0, ""},
	},
	"debug/elf": {
		{"(*File).Close", Method, 0, ""},
		{"(*File).DWARF", Method, 0, ""},
		{"(*File).DynString", Method, 1, ""},
		{"(*File).DynValue", Method, 21, ""},
		{"(*File).DynamicSymbols", Method, 4, ""},
		{"(*File).DynamicVersionNeeds", Method, 24, ""},
		{"(*File).DynamicVersions", Method, 24, ""},
		{"(*File).ImportedLibraries", Method, 0, ""},
		{"(*File).ImportedSymbols", Method, 0, ""},
		{"(*File).Section", Method, 0, ""},
		{"(*File).SectionByType", Method, 0, ""},
		{"(*File).Symbols", Method, 0, ""},
		{"(*FormatError).Error", Method, 0, ""},
		{"(*Prog).Open", Method, 0, ""},
		{"(*Section).Data", Method, 0, ""},
		{"(*Section).Open", Method, 0, ""},
		{"(Class).GoString", Method, 0, ""},
		{"(Class).String", Method, 0, ""},
		{"(CompressionType).GoString", Method, 6, ""},
		{"(CompressionType).String", Method, 6, ""},
		{"(Data).GoString", Method, 0, ""},
		{"(Data).String", Method, 0, ""},
		{"(DynFlag).GoString", Method, 0, ""},
		{"(DynFlag).String", Method, 0, ""},
		{"(DynFlag1).GoString", Method, 21, ""},
		{"(DynFlag1).String", Method, 21, ""},
		{"(DynTag).GoString", Method, 0, ""},
		{"(DynTag).String", Method, 0, ""},
		{"(Machine).GoString", Method, 0, ""},
		{"(Machine).String", Method, 0, ""},
		{"(NType).GoString", Method, 0, ""},
		{"(NType).String", Method, 0, ""},
		{"(OSABI).GoString", Method, 0, ""},
		{"(OSABI).String", Method, 0, ""},
		{"(Prog).ReadAt", Method, 0, ""},
		{"(ProgFlag).GoString", Method, 0, ""},
		{"(ProgFlag).String", Method, 0, ""},
		{"(ProgType).GoString", Method, 0, ""},
		{"(ProgType).String", Method, 0, ""},
		{"(R_386).GoString", Method, 0, ""},
		{"(R_386).String", Method, 0, ""},
		{"(R_390).GoString", Method, 7, ""},
		{"(R_390).String", Method, 7, ""},
		{"(R_AARCH64).GoString", Method, 4, ""},
		{"(R_AARCH64).String", Method, 4, ""},
		{"(R_ALPHA).GoString", Method, 0, ""},
		{"(R_ALPHA).String", Method, 0, ""},
		{"(R_ARM).GoString", Method, 0, ""},
		{"(R_ARM).String", Method, 0, ""},
		{"(R_LARCH).GoString", Method, 19, ""},
		{"(R_LARCH).String", Method, 19, ""},
		{"(R_MIPS).GoString", Method, 6, ""},
		{"(R_MIPS).String", Method, 6, ""},
		{"(R_PPC).GoString", Method, 0, ""},
		{"(R_PPC).String", Method, 0, ""},
		{"(R_PPC64).GoString", Method, 5, ""},
		{"(R_PPC64).String", Method, 5, ""},
		{"(R_RISCV).GoString", Method, 11, ""},
		{"(R_RISCV).String", Method, 11, ""},
		{"(R_SPARC).GoString", Method, 0, ""},
		{"(R_SPARC).String", Method, 0, ""},
		{"(R_X86_64).GoString", Method, 0, ""},
		{"(R_X86_64).String", Method, 0, ""},
		{"(Section).ReadAt", Method, 0, ""},
		{"(SectionFlag).GoString", Method, 0, ""},
		{"(SectionFlag).String", Method, 0, ""},
		{"(SectionIndex).GoString", Method, 0, ""},
		{"(SectionIndex).String", Method, 0, ""},
		{"(SectionType).GoString", Method, 0, ""},
		{"(SectionType).String", Method, 0, ""},
		{"(SymBind).GoString", Method, 0, ""},
		{"(SymBind).String", Method, 0, ""},
		{"(SymType).GoString", Method, 0, ""},
		{"(SymType).String", Method, 0, ""},
		{"(SymVis).GoString", Method, 0, ""},
		{"(SymVis).String", Method, 0, ""},
		{"(Type).GoString", Method, 0, ""},
		{"(Type).String", Method, 0, ""},
		{"(Version).GoString", Method, 0, ""},
		{"(Version).String", Method, 0, ""},
		{"(VersionIndex).Index", Method, 24, ""},
		{"(VersionIndex).IsHidden", Method, 24, ""},
		{"ARM_MAGIC_TRAMP_NUMBER", Const, 0, ""},
		{"COMPRESS_HIOS", Const, 6, ""},
		{"COMPRESS_HIPROC", Const, 6, ""},
		{"COMPRESS_LOOS", Const, 6, ""},
		{"COMPRESS_LOPROC", Const, 6, ""},
		{"COMPRESS_ZLIB", Const, 6, ""},
		{"COMPRESS_ZSTD", Const, 21, ""},
		{"Chdr32", Type, 6, ""},
		{"Chdr32.Addralign", Field, 6, ""},
		{"Chdr32.Size", Field, 6, ""},
		{"Chdr32.Type", Field, 6, ""},
		{"Chdr64", Type, 6, ""},
		{"Chdr64.Addralign", Field, 6, ""},
		{"Chdr64.Size", Field, 6, ""},
		{"Chdr64.Type", Field, 6, ""},
		{"Class", Type, 0, ""},
		{"CompressionType", Type, 6, ""},
		{"DF_1_CONFALT", Const, 21, ""},
		{"DF_1_DIRECT", Const, 21, ""},
		{"DF_1_DISPRELDNE", Const, 21, ""},
		{"DF_1_DISPRELPND", Const, 21, ""},
		{"DF_1_EDITED", Const, 21, ""},
		{"DF_1_ENDFILTEE", Const, 21, ""},
		{"DF_1_GLOBAL", Const, 21, ""},
		{"DF_1_GLOBAUDIT", Const, 21, ""},
		{"DF_1_GROUP", Const, 21, ""},
		{"DF_1_IGNMULDEF", Const, 21, ""},
		{"DF_1_INITFIRST", Const, 21, ""},
		{"DF_1_INTERPOSE", Const, 21, ""},
		{"DF_1_KMOD", Const, 21, ""},
		{"DF_1_LOADFLTR", Const, 21, ""},
		{"DF_1_NOCOMMON", Const, 21, ""},
		{"DF_1_NODEFLIB", Const, 21, ""},
		{"DF_1_NODELETE", Const, 21, ""},
		{"DF_1_NODIRECT", Const, 21, ""},
		{"DF_1_NODUMP", Const, 21, ""},
		{"DF_1_NOHDR", Const, 21, ""},
		{"DF_1_NOKSYMS", Const, 21, ""},
		{"DF_1_NOOPEN", Const, 21, ""},
		{"DF_1_NORELOC", Const, 21, ""},
		{"DF_1_NOW", Const, 21, ""},
		{"DF_1_ORIGIN", Const, 21, ""},
		{"DF_1_PIE", Const, 21, ""},
		{"DF_1_SINGLETON", Const, 21, ""},
		{"DF_1_STUB", Const, 21, ""},
		{"DF_1_SYMINTPOSE", Const, 21, ""},
		{"DF_1_TRANS", Const, 21, ""},
		{"DF_1_WEAKFILTER", Const, 21, ""},
		{"DF_BIND_NOW", Const, 0, ""},
		{"DF_ORIGIN", Const, 0, ""},
		{"DF_STATIC_TLS", Const, 0, ""},
		{"DF_SYMBOLIC", Const, 0, ""},
		{"DF_TEXTREL", Const, 0, ""},
		{"DT_ADDRRNGHI", Const, 16, ""},
		{"DT_ADDRRNGLO", Const, 16, ""},
		{"DT_AUDIT", Const, 16, ""},
		{"DT_AUXILIARY", Const, 16, ""},
		{"DT_BIND_NOW", Const, 0, ""},
		{"DT_CHECKSUM", Const, 16, ""},
		{"DT_CONFIG", Const, 16, ""},
		{"DT_DEBUG", Const, 0, ""},
		{"DT_DEPAUDIT", Const, 16, ""},
		{"DT_ENCODING", Const, 0, ""},
		{"DT_FEATURE", Const, 16, ""},
		{"DT_FILTER", Const, 16, ""},
		{"DT_FINI", Const, 0, ""},
		{"DT_FINI_ARRAY", Const, 0, ""},
		{"DT_FINI_ARRAYSZ", Const, 0, ""},
		{"DT_FLAGS", Const, 0, ""},
		{"DT_FLAGS_1", Const, 16, ""},
		{"DT_GNU_CONFLICT", Const, 16, ""},
		{"DT_GNU_CONFLICTSZ", Const, 16, ""},
		{"DT_GNU_HASH", Const, 16, ""},
		{"DT_GNU_LIBLIST", Const, 16, ""},
		{"DT_GNU_LIBLISTSZ", Const, 16, ""},
		{"DT_GNU_PRELINKED", Const, 16, ""},
		{"DT_HASH", Const, 0, ""},
		{"DT_HIOS", Const, 0, ""},
		{"DT_HIPROC", Const, 0, ""},
		{"DT_INIT", Const, 0, ""},
		{"DT_INIT_ARRAY", Const, 0, ""},
		{"DT_INIT_ARRAYSZ", Const, 0, ""},
		{"DT_JMPREL", Const, 0, ""},
		{"DT_LOOS", Const, 0, ""},
		{"DT_LOPROC", Const, 0, ""},
		{"DT_MIPS_AUX_DYNAMIC", Const, 16, ""},
		{"DT_MIPS_BASE_ADDRESS", Const, 16, ""},
		{"DT_MIPS_COMPACT_SIZE", Const, 16, ""},
		{"DT_MIPS_CONFLICT", Const, 16, ""},
		{"DT_MIPS_CONFLICTNO", Const, 16, ""},
		{"DT_MIPS_CXX_FLAGS", Const, 16, ""},
		{"DT_MIPS_DELTA_CLASS", Const, 16, ""},
		{"DT_MIPS_DELTA_CLASSSYM", Const, 16, ""},
		{"DT_MIPS_DELTA_CLASSSYM_NO", Const, 16, ""},
		{"DT_MIPS_DELTA_CLASS_NO", Const, 16, ""},
		{"DT_MIPS_DELTA_INSTANCE", Const, 16, ""},
		{"DT_MIPS_DELTA_INSTANCE_NO", Const, 16, ""},
		{"DT_MIPS_DELTA_RELOC", Const, 16, ""},
		{"DT_MIPS_DELTA_RELOC_NO", Const, 16, ""},
		{"DT_MIPS_DELTA_SYM", Const, 16, ""},
		{"DT_MIPS_DELTA_SYM_NO", Const, 16, ""},
		{"DT_MIPS_DYNSTR_ALIGN", Const, 16, ""},
		{"DT_MIPS_FLAGS", Const, 16, ""},
		{"DT_MIPS_GOTSYM", Const, 16, ""},
		{"DT_MIPS_GP_VALUE", Const, 16, ""},
		{"DT_MIPS_HIDDEN_GOTIDX", Const, 16, ""},
		{"DT_MIPS_HIPAGENO", Const, 16, ""},
		{"DT_MIPS_ICHECKSUM", Const, 16, ""},
		{"DT_MIPS_INTERFACE", Const, 16, ""},
		{"DT_MIPS_INTERFACE_SIZE", Const, 16, ""},
		{"DT_MIPS_IVERSION", Const, 16, ""},
		{"DT_MIPS_LIBLIST", Const, 16, ""},
		{"DT_MIPS_LIBLISTNO", Const, 16, ""},
		{"DT_MIPS_LOCALPAGE_GOTIDX", Const, 16, ""},
		{"DT_MIPS_LOCAL_GOTIDX", Const, 16, ""},
		{"DT_MIPS_LOCAL_GOTNO", Const, 16, ""},
		{"DT_MIPS_MSYM", Const, 16, ""},
		{"DT_MIPS_OPTIONS", Const, 16, ""},
		{"DT_MIPS_PERF_SUFFIX", Const, 16, ""},
		{"DT_MIPS_PIXIE_INIT", Const, 16, ""},
		{"DT_MIPS_PLTGOT", Const, 16, ""},
		{"DT_MIPS_PROTECTED_GOTIDX", Const, 16, ""},
		{"DT_MIPS_RLD_MAP", Const, 16, ""},
		{"DT_MIPS_RLD_MAP_REL", Const, 16, ""},
		{"DT_MIPS_RLD_TEXT_RESOLVE_ADDR", Const, 16, ""},
		{"DT_MIPS_RLD_VERSION", Const, 16, ""},
		{"DT_MIPS_RWPLT", Const, 16, ""},
		{"DT_MIPS_SYMBOL_LIB", Const, 16, ""},
		{"DT_MIPS_SYMTABNO", Const, 16, ""},
		{"DT_MIPS_TIME_STAMP", Const, 16, ""},
		{"DT_MIPS_UNREFEXTNO", Const, 16, ""},
		{"DT_MOVEENT", Const, 16, ""},
		{"DT_MOVESZ", Const, 16, ""},
		{"DT_MOVETAB", Const, 16, ""},
		{"DT_NEEDED", Const, 0, ""},
		{"DT_NULL", Const, 0, ""},
		{"DT_PLTGOT", Const, 0, ""},
		{"DT_PLTPAD", Const, 16, ""},
		{"DT_PLTPADSZ", Const, 16, ""},
		{"DT_PLTREL", Const, 0, ""},
		{"DT_PLTRELSZ", Const, 0, ""},
		{"DT_POSFLAG_1", Const, 16, ""},
		{"DT_PPC64_GLINK", Const, 16, ""},
		{"DT_PPC64_OPD", Const, 16, ""},
		{"DT_PPC64_OPDSZ", Const, 16, ""},
		{"DT_PPC64_OPT", Const, 16, ""},
		{"DT_PPC_GOT", Const, 16, ""},
		{"DT_PPC_OPT", Const, 16, ""},
		{"DT_PREINIT_ARRAY", Const, 0, ""},
		{"DT_PREINIT_ARRAYSZ", Const, 0, ""},
		{"DT_REL", Const, 0, ""},
		{"DT_RELA", Const, 0, ""},
		{"DT_RELACOUNT", Const, 16, ""},
		{"DT_RELAENT", Const, 0, ""},
		{"DT_RELASZ", Const, 0, ""},
		{"DT_RELCOUNT", Const, 16, ""},
		{"DT_RELENT", Const, 0, ""},
		{"DT_RELSZ", Const, 0, ""},
		{"DT_RPATH", Const, 0, ""},
		{"DT_RUNPATH", Const, 0, ""},
		{"DT_SONAME", Const, 0, ""},
		{"DT_SPARC_REGISTER", Const, 16, ""},
		{"DT_STRSZ", Const, 0, ""},
		{"DT_STRTAB", Const, 0, ""},
		{"DT_SYMBOLIC", Const, 0, ""},
		{"DT_SYMENT", Const, 0, ""},
		{"DT_SYMINENT", Const, 16, ""},
		{"DT_SYMINFO", Const, 16, ""},
		{"DT_SYMINSZ", Const, 16, ""},
		{"DT_SYMTAB", Const, 0, ""},
		{"DT_SYMTAB_SHNDX", Const, 16, ""},
		{"DT_TEXTREL", Const, 0, ""},
		{"DT_TLSDESC_GOT", Const, 16, ""},
		{"DT_TLSDESC_PLT", Const, 16, ""},
		{"DT_USED", Const, 16, ""},
		{"DT_VALRNGHI", Const, 16, ""},
		{"DT_VALRNGLO", Const, 16, ""},
		{"DT_VERDEF", Const, 16, ""},
		{"DT_VERDEFNUM", Const, 16, ""},
		{"DT_VERNEED", Const, 0, ""},
		{"DT_VERNEEDNUM", Const, 0, ""},
		{"DT_VERSYM", Const, 0, ""},
		{"Data", Type, 0, ""},
		{"Dyn32", Type, 0, ""},
		{"Dyn32.Tag", Field, 0, ""},
		{"Dyn32.Val", Field, 0, ""},
		{"Dyn64", Type, 0, ""},
		{"Dyn64.Tag", Field, 0, ""},
		{"Dyn64.Val", Field, 0, ""},
		{"DynFlag", Type, 0, ""},
		{"DynFlag1", Type, 21, ""},
		{"DynTag", Type, 0, ""},
		{"DynamicVersion", Type, 24, ""},
		{"DynamicVersion.Deps", Field, 24, ""},
		{"DynamicVersion.Flags", Field, 24, ""},
		{"DynamicVersion.Index", Field, 24, ""},
		{"DynamicVersion.Name", Field, 24, ""},
		{"DynamicVersionDep", Type, 24, ""},
		{"DynamicVersionDep.Dep", Field, 24, ""},
		{"DynamicVersionDep.Flags", Field, 24, ""},
		{"DynamicVersionDep.Index", Field, 24, ""},
		{"DynamicVersionFlag", Type, 24, ""},
		{"DynamicVersionNeed", Type, 24, ""},
		{"DynamicVersionNeed.Name", Field, 24, ""},
		{"DynamicVersionNeed.Needs", Field, 24, ""},
		{"EI_ABIVERSION", Const, 0, ""},
		{"EI_CLASS", Const, 0, ""},
		{"EI_DATA", Const, 0, ""},
		{"EI_NIDENT", Const, 0, ""},
		{"EI_OSABI", Const, 0, ""},
		{"EI_PAD", Const, 0, ""},
		{"EI_VERSION", Const, 0, ""},
		{"ELFCLASS32", Const, 0, ""},
		{"ELFCLASS64", Const, 0, ""},
		{"ELFCLASSNONE", Const, 0, ""},
		{"ELFDATA2LSB", Const, 0, ""},
		{"ELFDATA2MSB", Const, 0, ""},
		{"ELFDATANONE", Const, 0, ""},
		{"ELFMAG", Const, 0, ""},
		{"ELFOSABI_86OPEN", Const, 0, ""},
		{"ELFOSABI_AIX", Const, 0, ""},
		{"ELFOSABI_ARM", Const, 0, ""},
		{"ELFOSABI_AROS", Const, 11, ""},
		{"ELFOSABI_CLOUDABI", Const, 11, ""},
		{"ELFOSABI_FENIXOS", Const, 11, ""},
		{"ELFOSABI_FREEBSD", Const, 0, ""},
		{"ELFOSABI_HPUX", Const, 0, ""},
		{"ELFOSABI_HURD", Const, 0, ""},
		{"ELFOSABI_IRIX", Const, 0, ""},
		{"ELFOSABI_LINUX", Const, 0, ""},
		{"ELFOSABI_MODESTO", Const, 0, ""},
		{"ELFOSABI_NETBSD", Const, 0, ""},
		{"ELFOSABI_NONE", Const, 0, ""},
		{"ELFOSABI_NSK", Const, 0, ""},
		{"ELFOSABI_OPENBSD", Const, 0, ""},
		{"ELFOSABI_OPENVMS", Const, 0, ""},
		{"ELFOSABI_SOLARIS", Const, 0, ""},
		{"ELFOSABI_STANDALONE", Const, 0, ""},
		{"ELFOSABI_TRU64", Const, 0, ""},
		{"EM_386", Const, 0, ""},
		{"EM_486", Const, 0, ""},
		{"EM_56800EX", Const, 11, ""},
		{"EM_68HC05", Const, 11, ""},
		{"EM_68HC08", Const, 11, ""},
		{"EM_68HC11", Const, 11, ""},
		{"EM_68HC12", Const, 0, ""},
		{"EM_68HC16", Const, 11, ""},
		{"EM_68K", Const, 0, ""},
		{"EM_78KOR", Const, 11, ""},
		{"EM_8051", Const, 11, ""},
		{"EM_860", Const, 0, ""},
		{"EM_88K", Const, 0, ""},
		{"EM_960", Const, 0, ""},
		{"EM_AARCH64", Const, 4, ""},
		{"EM_ALPHA", Const, 0, ""},
		{"EM_ALPHA_STD", Const, 0, ""},
		{"EM_ALTERA_NIOS2", Const, 11, ""},
		{"EM_AMDGPU", Const, 11, ""},
		{"EM_ARC", Const, 0, ""},
		{"EM_ARCA", Const, 11, ""},
		{"EM_ARC_COMPACT", Const, 11, ""},
		{"EM_ARC_COMPACT2", Const, 11, ""},
		{"EM_ARM", Const, 0, ""},
		{"EM_AVR", Const, 11, ""},
		{"EM_AVR32", Const, 11, ""},
		{"EM_BA1", Const, 11, ""},
		{"EM_BA2", Const, 11, ""},
		{"EM_BLACKFIN", Const, 11, ""},
		{"EM_BPF", Const, 11, ""},
		{"EM_C166", Const, 11, ""},
		{"EM_CDP", Const, 11, ""},
		{"EM_CE", Const, 11, ""},
		{"EM_CLOUDSHIELD", Const, 11, ""},
		{"EM_COGE", Const, 11, ""},
		{"EM_COLDFIRE", Const, 0, ""},
		{"EM_COOL", Const, 11, ""},
		{"EM_COREA_1ST", Const, 11, ""},
		{"EM_COREA_2ND", Const, 11, ""},
		{"EM_CR", Const, 11, ""},
		{"EM_CR16", Const, 11, ""},
		{"EM_CRAYNV2", Const, 11, ""},
		{"EM_CRIS", Const, 11, ""},
		{"EM_CRX", Const, 11, ""},
		{"EM_CSR_KALIMBA", Const, 11, ""},
		{"EM_CUDA", Const, 11, ""},
		{"EM_CYPRESS_M8C", Const, 11, ""},
		{"EM_D10V", Const, 11, ""},
		{"EM_D30V", Const, 11, ""},
		{"EM_DSP24", Const, 11, ""},
		{"EM_DSPIC30F", Const, 11, ""},
		{"EM_DXP", Const, 11, ""},
		{"EM_ECOG1", Const, 11, ""},
		{"EM_ECOG16", Const, 11, ""},
		{"EM_ECOG1X", Const, 11, ""},
		{"EM_ECOG2", Const, 11, ""},
		{"EM_ETPU", Const, 11, ""},
		{"EM_EXCESS", Const, 11, ""},
		{"EM_F2MC16", Const, 11, ""},
		{"EM_FIREPATH", Const, 11, ""},
		{"EM_FR20", Const, 0, ""},
		{"EM_FR30", Const, 11, ""},
		{"EM_FT32", Const, 11, ""},
		{"EM_FX66", Const, 11, ""},
		{"EM_H8S", Const, 0, ""},
		{"EM_H8_300", Const, 0, ""},
		{"EM_H8_300H", Const, 0, ""},
		{"EM_H8_500", Const, 0, ""},
		{"EM_HUANY", Const, 11, ""},
		{"EM_IA_64", Const, 0, ""},
		{"EM_INTEL205", Const, 11, ""},
		{"EM_INTEL206", Const, 11, ""},
		{"EM_INTEL207", Const, 11, ""},
		{"EM_INTEL208", Const, 11, ""},
		{"EM_INTEL209", Const, 11, ""},
		{"EM_IP2K", Const, 11, ""},
		{"EM_JAVELIN", Const, 11, ""},
		{"EM_K10M", Const, 11, ""},
		{"EM_KM32", Const, 11, ""},
		{"EM_KMX16", Const, 11, ""},
		{"EM_KMX32", Const, 11, ""},
		{"EM_KMX8", Const, 11, ""},
		{"EM_KVARC", Const, 11, ""},
		{"EM_L10M", Const, 11, ""},
		{"EM_LANAI", Const, 11, ""},
		{"EM_LATTICEMICO32", Const, 11, ""},
		{"EM_LOONGARCH", Const, 19, ""},
		{"EM_M16C", Const, 11, ""},
		{"EM_M32", Const, 0, ""},
		{"EM_M32C", Const, 11, ""},
		{"EM_M32R", Const, 11, ""},
		{"EM_MANIK", Const, 11, ""},
		{"EM_MAX", Const, 11, ""},
		{"EM_MAXQ30", Const, 11, ""},
		{"EM_MCHP_PIC", Const, 11, ""},
		{"EM_MCST_ELBRUS", Const, 11, ""},
		{"EM_ME16", Const, 0, ""},
		{"EM_METAG", Const, 11, ""},
		{"EM_MICROBLAZE", Const, 11, ""},
		{"EM_MIPS", Const, 0, ""},
		{"EM_MIPS_RS3_LE", Const, 0, ""},
		{"EM_MIPS_RS4_BE", Const, 0, ""},
		{"EM_MIPS_X", Const, 0, ""},
		{"EM_MMA", Const, 0, ""},
		{"EM_MMDSP_PLUS", Const, 11, ""},
		{"EM_MMIX", Const, 11, ""},
		{"EM_MN10200", Const, 11, ""},
		{"EM_MN10300", Const, 11, ""},
		{"EM_MOXIE", Const, 11, ""},
		{"EM_MSP430", Const, 11, ""},
		{"EM_NCPU", Const, 0, ""},
		{"EM_NDR1", Const, 0, ""},
		{"EM_NDS32", Const, 11, ""},
		{"EM_NONE", Const, 0, ""},
		{"EM_NORC", Const, 11, ""},
		{"EM_NS32K", Const, 11, ""},
		{"EM_OPEN8", Const, 11, ""},
		{"EM_OPENRISC", Const, 11, ""},
		{"EM_PARISC", Const, 0, ""},
		{"EM_PCP", Const, 0, ""},
		{"EM_PDP10", Const, 11, ""},
		{"EM_PDP11", Const, 11, ""},
		{"EM_PDSP", Const, 11, ""},
		{"EM_PJ", Const, 11, ""},
		{"EM_PPC", Const, 0, ""},
		{"EM_PPC64", Const, 0, ""},
		{"EM_PRISM", Const, 11, ""},
		{"EM_QDSP6", Const, 11, ""},
		{"EM_R32C", Const, 11, ""},
		{"EM_RCE", Const, 0, ""},
		{"EM_RH32", Const, 0, ""},
		{"EM_RISCV", Const, 11, ""},
		{"EM_RL78", Const, 11, ""},
		{"EM_RS08", Const, 11, ""},
		{"EM_RX", Const, 11, ""},
		{"EM_S370", Const, 0, ""},
		{"EM_S390", Const, 0, ""},
		{"EM_SCORE7", Const, 11, ""},
		{"EM_SEP", Const, 11, ""},
		{"EM_SE_C17", Const, 11, ""},
		{"EM_SE_C33", Const, 11, ""},
		{"EM_SH", Const, 0, ""},
		{"EM_SHARC", Const, 11, ""},
		{"EM_SLE9X", Const, 11, ""},
		{"EM_SNP1K", Const, 11, ""},
		{"EM_SPARC", Const, 0, ""},
		{"EM_SPARC32PLUS", Const, 0, ""},
		{"EM_SPARCV9", Const, 0, ""},
		{"EM_ST100", Const, 0, ""},
		{"EM_ST19", Const, 11, ""},
		{"EM_ST200", Const, 11, ""},
		{"EM_ST7", Const, 11, ""},
		{"EM_ST9PLUS", Const, 11, ""},
		{"EM_STARCORE", Const, 0, ""},
		{"EM_STM8", Const, 11, ""},
		{"EM_STXP7X", Const, 11, ""},
		{"EM_SVX", Const, 11, ""},
		{"EM_TILE64", Const, 11, ""},
		{"EM_TILEGX", Const, 11, ""},
		{"EM_TILEPRO", Const, 11, ""},
		{"EM_TINYJ", Const, 0, ""},
		{"EM_TI_ARP32", Const, 11, ""},
		{"EM_TI_C2000", Const, 11, ""},
		{"EM_TI_C5500", Const, 11, ""},
		{"EM_TI_C6000", Const, 11, ""},
		{"EM_TI_PRU", Const, 11, ""},
		{"EM_TMM_GPP", Const, 11, ""},
		{"EM_TPC", Const, 11, ""},
		{"EM_TRICORE", Const, 0, ""},
		{"EM_TRIMEDIA", Const, 11, ""},
		{"EM_TSK3000", Const, 11, ""},
		{"EM_UNICORE", Const, 11, ""},
		{"EM_V800", Const, 0, ""},
		{"EM_V850", Const, 11, ""},
		{"EM_VAX", Const, 11, ""},
		{"EM_VIDEOCORE", Const, 11, ""},
		{"EM_VIDEOCORE3", Const, 11, ""},
		{"EM_VIDEOCORE5", Const, 11, ""},
		{"EM_VISIUM", Const, 11, ""},
		{"EM_VPP500", Const, 0, ""},
		{"EM_X86_64", Const, 0, ""},
		{"EM_XCORE", Const, 11, ""},
		{"EM_XGATE", Const, 11, ""},
		{"EM_XIMO16", Const, 11, ""},
		{"EM_XTENSA", Const, 11, ""},
		{"EM_Z80", Const, 11, ""},
		{"EM_ZSP", Const, 11, ""},
		{"ET_CORE", Const, 0, ""},
		{"ET_DYN", Const, 0, ""},
		{"ET_EXEC", Const, 0, ""},
		{"ET_HIOS", Const, 0, ""},
		{"ET_HIPROC", Const, 0, ""},
		{"ET_LOOS", Const, 0, ""},
		{"ET_LOPROC", Const, 0, ""},
		{"ET_NONE", Const, 0, ""},
		{"ET_REL", Const, 0, ""},
		{"EV_CURRENT", Const, 0, ""},
		{"EV_NONE", Const, 0, ""},
		{"ErrNoSymbols", Var, 4, ""},
		{"File", Type, 0, ""},
		{"File.FileHeader", Field, 0, ""},
		{"File.Progs", Field, 0, ""},
		{"File.Sections", Field, 0, ""},
		{"FileHeader", Type, 0, ""},
		{"FileHeader.ABIVersion", Field, 0, ""},
		{"FileHeader.ByteOrder", Field, 0, ""},
		{"FileHeader.Class", Field, 0, ""},
		{"FileHeader.Data", Field, 0, ""},
		{"FileHeader.Entry", Field, 1, ""},
		{"FileHeader.Machine", Field, 0, ""},
		{"FileHeader.OSABI", Field, 0, ""},
		{"FileHeader.Type", Field, 0, ""},
		{"FileHeader.Version", Field, 0, ""},
		{"FormatError", Type, 0, ""},
		{"Header32", Type, 0, ""},
		{"Header32.Ehsize", Field, 0, ""},
		{"Header32.Entry", Field, 0, ""},
		{"Header32.Flags", Field, 0, ""},
		{"Header32.Ident", Field, 0, ""},
		{"Header32.Machine", Field, 0, ""},
		{"Header32.Phentsize", Field, 0, ""},
		{"Header32.Phnum", Field, 0, ""},
		{"Header32.Phoff", Field, 0, ""},
		{"Header32.Shentsize", Field, 0, ""},
		{"Header32.Shnum", Field, 0, ""},
		{"Header32.Shoff", Field, 0, ""},
		{"Header32.Shstrndx", Field, 0, ""},
		{"Header32.Type", Field, 0, ""},
		{"Header32.Version", Field, 0, ""},
		{"Header64", Type, 0, ""},
		{"Header64.Ehsize", Field, 0, ""},
		{"Header64.Entry", Field, 0, ""},
		{"Header64.Flags", Field, 0, ""},
		{"Header64.Ident", Field, 0, ""},
		{"Header64.Machine", Field, 0, ""},
		{"Header64.Phentsize", Field, 0, ""},
		{"Header64.Phnum", Field, 0, ""},
		{"Header64.Phoff", Field, 0, ""},
		{"Header64.Shentsize", Field, 0, ""},
		{"Header64.Shnum", Field, 0, ""},
		{"Header64.Shoff", Field, 0, ""},
		{"Header64.Shstrndx", Field, 0, ""},
		{"Header64.Type", Field, 0, ""},
		{"Header64.Version", Field, 0, ""},
		{"ImportedSymbol", Type, 0, ""},
		{"ImportedSymbol.Library", Field, 0, ""},
		{"ImportedSymbol.Name", Field, 0, ""},
		{"ImportedSymbol.Version", Field, 0, ""},
		{"Machine", Type, 0, ""},
		{"NT_FPREGSET", Const, 0, ""},
		{"NT_PRPSINFO", Const, 0, ""},
		{"NT_PRSTATUS", Const, 0, ""},
		{"NType", Type, 0, ""},
		{"NewFile", Func, 0, "func(r io.ReaderAt) (*File, error)"},
		{"OSABI", Type, 0, ""},
		{"Open", Func, 0, "func(name string) (*File, error)"},
		{"PF_MASKOS", Const, 0, ""},
		{"PF_MASKPROC", Const, 0, ""},
		{"PF_R", Const, 0, ""},
		{"PF_W", Const, 0, ""},
		{"PF_X", Const, 0, ""},
		{"PT_AARCH64_ARCHEXT", Const, 16, ""},
		{"PT_AARCH64_UNWIND", Const, 16, ""},
		{"PT_ARM_ARCHEXT", Const, 16, ""},
		{"PT_ARM_EXIDX", Const, 16, ""},
		{"PT_DYNAMIC", Const, 0, ""},
		{"PT_GNU_EH_FRAME", Const, 16, ""},
		{"PT_GNU_MBIND_HI", Const, 16, ""},
		{"PT_GNU_MBIND_LO", Const, 16, ""},
		{"PT_GNU_PROPERTY", Const, 16, ""},
		{"PT_GNU_RELRO", Const, 16, ""},
		{"PT_GNU_STACK", Const, 16, ""},
		{"PT_HIOS", Const, 0, ""},
		{"PT_HIPROC", Const, 0, ""},
		{"PT_INTERP", Const, 0, ""},
		{"PT_LOAD", Const, 0, ""},
		{"PT_LOOS", Const, 0, ""},
		{"PT_LOPROC", Const, 0, ""},
		{"PT_MIPS_ABIFLAGS", Const, 16, ""},
		{"PT_MIPS_OPTIONS", Const, 16, ""},
		{"PT_MIPS_REGINFO", Const, 16, ""},
		{"PT_MIPS_RTPROC", Const, 16, ""},
		{"PT_NOTE", Const, 0, ""},
		{"PT_NULL", Const, 0, ""},
		{"PT_OPENBSD_BOOTDATA", Const, 16, ""},
		{"PT_OPENBSD_NOBTCFI", Const, 23, ""},
		{"PT_OPENBSD_RANDOMIZE", Const, 16, ""},
		{"PT_OPENBSD_WXNEEDED", Const, 16, ""},
		{"PT_PAX_FLAGS", Const, 16, ""},
		{"PT_PHDR", Const, 0, ""},
		{"PT_RISCV_ATTRIBUTES", Const, 25, ""},
		{"PT_S390_PGSTE", Const, 16, ""},
		{"PT_SHLIB", Const, 0, ""},
		{"PT_SUNWSTACK", Const, 16, ""},
		{"PT_SUNW_EH_FRAME", Const, 16, ""},
		{"PT_TLS", Const, 0, ""},
		{"Prog", Type, 0, ""},
		{"Prog.ProgHeader", Field, 0, ""},
		{"Prog.ReaderAt", Field, 0, ""},
		{"Prog32", Type, 0, ""},
		{"Prog32.Align", Field, 0, ""},
		{"Prog32.Filesz", Field, 0, ""},
		{"Prog32.Flags", Field, 0, ""},
		{"Prog32.Memsz", Field, 0, ""},
		{"Prog32.Off", Field, 0, ""},
		{"Prog32.Paddr", Field, 0, ""},
		{"Prog32.Type", Field, 0, ""},
		{"Prog32.Vaddr", Field, 0, ""},
		{"Prog64", Type, 0, ""},
		{"Prog64.Align", Field, 0, ""},
		{"Prog64.Filesz", Field, 0, ""},
		{"Prog64.Flags", Field, 0, ""},
		{"Prog64.Memsz", Field, 0, ""},
		{"Prog64.Off", Field, 0, ""},
		{"Prog64.Paddr", Field, 0, ""},
		{"Prog64.Type", Field, 0, ""},
		{"Prog64.Vaddr", Field, 0, ""},
		{"ProgFlag", Type, 0, ""},
		{"ProgHeader", Type, 0, ""},
		{"ProgHeader.Align", Field, 0, ""},
		{"ProgHeader.Filesz", Field, 0, ""},
		{"ProgHeader.Flags", Field, 0, ""},
		{"ProgHeader.Memsz", Field, 0, ""},
		{"ProgHeader.Off", Field, 0, ""},
		{"ProgHeader.Paddr", Field, 0, ""},
		{"ProgHeader.Type", Field, 0, ""},
		{"ProgHeader.Vaddr", Field, 0, ""},
		{"ProgType", Type, 0, ""},
		{"R_386", Type, 0, ""},
		{"R_386_16", Const, 10, ""},
		{"R_386_32", Const, 0, ""},
		{"R_386_32PLT", Const, 10, ""},
		{"R_386_8", Const, 10, ""},
		{"R_386_COPY", Const, 0, ""},
		{"R_386_GLOB_DAT", Const, 0, ""},
		{"R_386_GOT32", Const, 0, ""},
		{"R_386_GOT32X", Const, 10, ""},
		{"R_386_GOTOFF", Const, 0, ""},
		{"R_386_GOTPC", Const, 0, ""},
		{"R_386_IRELATIVE", Const, 10, ""},
		{"R_386_JMP_SLOT", Const, 0, ""},
		{"R_386_NONE", Const, 0, ""},
		{"R_386_PC16", Const, 10, ""},
		{"R_386_PC32", Const, 0, ""},
		{"R_386_PC8", Const, 10, ""},
		{"R_386_PLT32", Const, 0, ""},
		{"R_386_RELATIVE", Const, 0, ""},
		{"R_386_SIZE32", Const, 10, ""},
		{"R_386_TLS_DESC", Const, 10, ""},
		{"R_386_TLS_DESC_CALL", Const, 10, ""},
		{"R_386_TLS_DTPMOD32", Const, 0, ""},
		{"R_386_TLS_DTPOFF32", Const, 0, ""},
		{"R_386_TLS_GD", Const, 0, ""},
		{"R_386_TLS_GD_32", Const, 0, ""},
		{"R_386_TLS_GD_CALL", Const, 0, ""},
		{"R_386_TLS_GD_POP", Const, 0, ""},
		{"R_386_TLS_GD_PUSH", Const, 0, ""},
		{"R_386_TLS_GOTDESC", Const, 10, ""},
		{"R_386_TLS_GOTIE", Const, 0, ""},
		{"R_386_TLS_IE", Const, 0, ""},
		{"R_386_TLS_IE_32", Const, 0, ""},
		{"R_386_TLS_LDM", Const, 0, ""},
		{"R_386_TLS_LDM_32", Const, 0, ""},
		{"R_386_TLS_LDM_CALL", Const, 0, ""},
		{"R_386_TLS_LDM_POP", Const, 0, ""},
		{"R_386_TLS_LDM_PUSH", Const, 0, ""},
		{"R_386_TLS_LDO_32", Const, 0, ""},
		{"R_386_TLS_LE", Const, 0, ""},
		{"R_386_TLS_LE_32", Const, 0, ""},
		{"R_386_TLS_TPOFF", Const, 0, ""},
		{"R_386_TLS_TPOFF32", Const, 0, ""},
		{"R_390", Type, 7, ""},
		{"R_390_12", Const, 7, ""},
		{"R_390_16", Const, 7, ""},
		{"R_390_20", Const, 7, ""},
		{"R_390_32", Const, 7, ""},
		{"R_390_64", Const, 7, ""},
		{"R_390_8", Const, 7, ""},
		{"R_390_COPY", Const, 7, ""},
		{"R_390_GLOB_DAT", Const, 7, ""},
		{"R_390_GOT12", Const, 7, ""},
		{"R_390_GOT16", Const, 7, ""},
		{"R_390_GOT20", Const, 7, ""},
		{"R_390_GOT32", Const, 7, ""},
		{"R_390_GOT64", Const, 7, ""},
		{"R_390_GOTENT", Const, 7, ""},
		{"R_390_GOTOFF", Const, 7, ""},
		{"R_390_GOTOFF16", Const, 7, ""},
		{"R_390_GOTOFF64", Const, 7, ""},
		{"R_390_GOTPC", Const, 7, ""},
		{"R_390_GOTPCDBL", Const, 7, ""},
		{"R_390_GOTPLT12", Const, 7, ""},
		{"R_390_GOTPLT16", Const, 7, ""},
		{"R_390_GOTPLT20", Const, 7, ""},
		{"R_390_GOTPLT32", Const, 7, ""},
		{"R_390_GOTPLT64", Const, 7, ""},
		{"R_390_GOTPLTENT", Const, 7, ""},
		{"R_390_GOTPLTOFF16", Const, 7, ""},
		{"R_390_GOTPLTOFF32", Const, 7, ""},
		{"R_390_GOTPLTOFF64", Const, 7, ""},
		{"R_390_JMP_SLOT", Const, 7, ""},
		{"R_390_NONE", Const, 7, ""},
		{"R_390_PC16", Const, 7, ""},
		{"R_390_PC16DBL", Const, 7, ""},
		{"R_390_PC32", Const, 7, ""},
		{"R_390_PC32DBL", Const, 7, ""},
		{"R_390_PC64", Const, 7, ""},
		{"R_390_PLT16DBL", Const, 7, ""},
		{"R_390_PLT32", Const, 7, ""},
		{"R_390_PLT32DBL", Const, 7, ""},
		{"R_390_PLT64", Const, 7, ""},
		{"R_390_RELATIVE", Const, 7, ""},
		{"R_390_TLS_DTPMOD", Const, 7, ""},
		{"R_390_TLS_DTPOFF", Const, 7, ""},
		{"R_390_TLS_GD32", Const, 7, ""},
		{"R_390_TLS_GD64", Const, 7, ""},
		{"R_390_TLS_GDCALL", Const, 7, ""},
		{"R_390_TLS_GOTIE12", Const, 7, ""},
		{"R_390_TLS_GOTIE20", Const, 7, ""},
		{"R_390_TLS_GOTIE32", Const, 7, ""},
		{"R_390_TLS_GOTIE64", Const, 7, ""},
		{"R_390_TLS_IE32", Const, 7, ""},
		{"R_390_TLS_IE64", Const, 7, ""},
		{"R_390_TLS_IEENT", Const, 7, ""},
		{"R_390_TLS_LDCALL", Const, 7, ""},
		{"R_390_TLS_LDM32", Const, 7, ""},
		{"R_390_TLS_LDM64", Const, 7, ""},
		{"R_390_TLS_LDO32", Const, 7, ""},
		{"R_390_TLS_LDO64", Const, 7, ""},
		{"R_390_TLS_LE32", Const, 7, ""},
		{"R_390_TLS_LE64", Const, 7, ""},
		{"R_390_TLS_LOAD", Const, 7, ""},
		{"R_390_TLS_TPOFF", Const, 7, ""},
		{"R_AARCH64", Type, 4, ""},
		{"R_AARCH64_ABS16", Const, 4, ""},
		{"R_AARCH64_ABS32", Const, 4, ""},
		{"R_AARCH64_ABS64", Const, 4, ""},
		{"R_AARCH64_ADD_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_ADR_GOT_PAGE", Const, 4, ""},
		{"R_AARCH64_ADR_PREL_LO21", Const, 4, ""},
		{"R_AARCH64_ADR_PREL_PG_HI21", Const, 4, ""},
		{"R_AARCH64_ADR_PREL_PG_HI21_NC", Const, 4, ""},
		{"R_AARCH64_CALL26", Const, 4, ""},
		{"R_AARCH64_CONDBR19", Const, 4, ""},
		{"R_AARCH64_COPY", Const, 4, ""},
		{"R_AARCH64_GLOB_DAT", Const, 4, ""},
		{"R_AARCH64_GOT_LD_PREL19", Const, 4, ""},
		{"R_AARCH64_IRELATIVE", Const, 4, ""},
		{"R_AARCH64_JUMP26", Const, 4, ""},
		{"R_AARCH64_JUMP_SLOT", Const, 4, ""},
		{"R_AARCH64_LD64_GOTOFF_LO15", Const, 10, ""},
		{"R_AARCH64_LD64_GOTPAGE_LO15", Const, 10, ""},
		{"R_AARCH64_LD64_GOT_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LDST128_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LDST16_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LDST32_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LDST64_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LDST8_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_LD_PREL_LO19", Const, 4, ""},
		{"R_AARCH64_MOVW_SABS_G0", Const, 4, ""},
		{"R_AARCH64_MOVW_SABS_G1", Const, 4, ""},
		{"R_AARCH64_MOVW_SABS_G2", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G0", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G0_NC", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G1", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G1_NC", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G2", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G2_NC", Const, 4, ""},
		{"R_AARCH64_MOVW_UABS_G3", Const, 4, ""},
		{"R_AARCH64_NONE", Const, 4, ""},
		{"R_AARCH64_NULL", Const, 4, ""},
		{"R_AARCH64_P32_ABS16", Const, 4, ""},
		{"R_AARCH64_P32_ABS32", Const, 4, ""},
		{"R_AARCH64_P32_ADD_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_ADR_GOT_PAGE", Const, 4, ""},
		{"R_AARCH64_P32_ADR_PREL_LO21", Const, 4, ""},
		{"R_AARCH64_P32_ADR_PREL_PG_HI21", Const, 4, ""},
		{"R_AARCH64_P32_CALL26", Const, 4, ""},
		{"R_AARCH64_P32_CONDBR19", Const, 4, ""},
		{"R_AARCH64_P32_COPY", Const, 4, ""},
		{"R_AARCH64_P32_GLOB_DAT", Const, 4, ""},
		{"R_AARCH64_P32_GOT_LD_PREL19", Const, 4, ""},
		{"R_AARCH64_P32_IRELATIVE", Const, 4, ""},
		{"R_AARCH64_P32_JUMP26", Const, 4, ""},
		{"R_AARCH64_P32_JUMP_SLOT", Const, 4, ""},
		{"R_AARCH64_P32_LD32_GOT_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LDST128_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LDST16_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LDST32_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LDST64_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LDST8_ABS_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_LD_PREL_LO19", Const, 4, ""},
		{"R_AARCH64_P32_MOVW_SABS_G0", Const, 4, ""},
		{"R_AARCH64_P32_MOVW_UABS_G0", Const, 4, ""},
		{"R_AARCH64_P32_MOVW_UABS_G0_NC", Const, 4, ""},
		{"R_AARCH64_P32_MOVW_UABS_G1", Const, 4, ""},
		{"R_AARCH64_P32_PREL16", Const, 4, ""},
		{"R_AARCH64_P32_PREL32", Const, 4, ""},
		{"R_AARCH64_P32_RELATIVE", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_ADD_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_ADR_PAGE21", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_ADR_PREL21", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_CALL", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_LD32_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSDESC_LD_PREL19", Const, 4, ""},
		{"R_AARCH64_P32_TLSGD_ADD_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSGD_ADR_PAGE21", Const, 4, ""},
		{"R_AARCH64_P32_TLSIE_ADR_GOTTPREL_PAGE21", Const, 4, ""},
		{"R_AARCH64_P32_TLSIE_LD32_GOTTPREL_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSIE_LD_GOTTPREL_PREL19", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_ADD_TPREL_HI12", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_ADD_TPREL_LO12", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_ADD_TPREL_LO12_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_MOVW_TPREL_G0", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_MOVW_TPREL_G0_NC", Const, 4, ""},
		{"R_AARCH64_P32_TLSLE_MOVW_TPREL_G1", Const, 4, ""},
		{"R_AARCH64_P32_TLS_DTPMOD", Const, 4, ""},
		{"R_AARCH64_P32_TLS_DTPREL", Const, 4, ""},
		{"R_AARCH64_P32_TLS_TPREL", Const, 4, ""},
		{"R_AARCH64_P32_TSTBR14", Const, 4, ""},
		{"R_AARCH64_PREL16", Const, 4, ""},
		{"R_AARCH64_PREL32", Const, 4, ""},
		{"R_AARCH64_PREL64", Const, 4, ""},
		{"R_AARCH64_RELATIVE", Const, 4, ""},
		{"R_AARCH64_TLSDESC", Const, 4, ""},
		{"R_AARCH64_TLSDESC_ADD", Const, 4, ""},
		{"R_AARCH64_TLSDESC_ADD_LO12_NC", Const, 4, ""},
		{"R_AARCH64_TLSDESC_ADR_PAGE21", Const, 4, ""},
		{"R_AARCH64_TLSDESC_ADR_PREL21", Const, 4, ""},
		{"R_AARCH64_TLSDESC_CALL", Const, 4, ""},
		{"R_AARCH64_TLSDESC_LD64_LO12_NC", Const, 4, ""},
		{"R_AARCH64_TLSDESC_LDR", Const, 4, ""},
		{"R_AARCH64_TLSDESC_LD_PREL19", Const, 4, ""},
		{"R_AARCH64_TLSDESC_OFF_G0_NC", Const, 4, ""},
		{"R_AARCH64_TLSDESC_OFF_G1", Const, 4, ""},
		{"R_AARCH64_TLSGD_ADD_LO12_NC", Const, 4, ""},
		{"R_AARCH64_TLSGD_ADR_PAGE21", Const, 4, ""},
		{"R_AARCH64_TLSGD_ADR_PREL21", Const, 10, ""},
		{"R_AARCH64_TLSGD_MOVW_G0_NC", Const, 10, ""},
		{"R_AARCH64_TLSGD_MOVW_G1", Const, 10, ""},
		{"R_AARCH64_TLSIE_ADR_GOTTPREL_PAGE21", Const, 4, ""},
		{"R_AARCH64_TLSIE_LD64_GOTTPREL_LO12_NC", Const, 4, ""},
		{"R_AARCH64_TLSIE_LD_GOTTPREL_PREL19", Const, 4, ""},
		{"R_AARCH64_TLSIE_MOVW_GOTTPREL_G0_NC", Const, 4, ""},
		{"R_AARCH64_TLSIE_MOVW_GOTTPREL_G1", Const, 4, ""},
		{"R_AARCH64_TLSLD_ADR_PAGE21", Const, 10, ""},
		{"R_AARCH64_TLSLD_ADR_PREL21", Const, 10, ""},
		{"R_AARCH64_TLSLD_LDST128_DTPREL_LO12", Const, 10, ""},
		{"R_AARCH64_TLSLD_LDST128_DTPREL_LO12_NC", Const, 10, ""},
		{"R_AARCH64_TLSLE_ADD_TPREL_HI12", Const, 4, ""},
		{"R_AARCH64_TLSLE_ADD_TPREL_LO12", Const, 4, ""},
		{"R_AARCH64_TLSLE_ADD_TPREL_LO12_NC", Const, 4, ""},
		{"R_AARCH64_TLSLE_LDST128_TPREL_LO12", Const, 10, ""},
		{"R_AARCH64_TLSLE_LDST128_TPREL_LO12_NC", Const, 10, ""},
		{"R_AARCH64_TLSLE_MOVW_TPREL_G0", Const, 4, ""},
		{"R_AARCH64_TLSLE_MOVW_TPREL_G0_NC", Const, 4, ""},
		{"R_AARCH64_TLSLE_MOVW_TPREL_G1", Const, 4, ""},
		{"R_AARCH64_TLSLE_MOVW_TPREL_G1_NC", Const, 4, ""},
		{"R_AARCH64_TLSLE_MOVW_TPREL_G2", Const, 4, ""},
		{"R_AARCH64_TLS_DTPMOD64", Const, 4, ""},
		{"R_AARCH64_TLS_DTPREL64", Const, 4, ""},
		{"R_AARCH64_TLS_TPREL64", Const, 4, ""},
		{"R_AARCH64_TSTBR14", Const, 4, ""},
		{"R_ALPHA", Type, 0, ""},
		{"R_ALPHA_BRADDR", Const, 0, ""},
		{"R_ALPHA_COPY", Const, 0, ""},
		{"R_ALPHA_GLOB_DAT", Const, 0, ""},
		{"R_ALPHA_GPDISP", Const, 0, ""},
		{"R_ALPHA_GPREL32", Const, 0, ""},
		{"R_ALPHA_GPRELHIGH", Const, 0, ""},
		{"R_ALPHA_GPRELLOW", Const, 0, ""},
		{"R_ALPHA_GPVALUE", Const, 0, ""},
		{"R_ALPHA_HINT", Const, 0, ""},
		{"R_ALPHA_IMMED_BR_HI32", Const, 0, ""},
		{"R_ALPHA_IMMED_GP_16", Const, 0, ""},
		{"R_ALPHA_IMMED_GP_HI32", Const, 0, ""},
		{"R_ALPHA_IMMED_LO32", Const, 0, ""},
		{"R_ALPHA_IMMED_SCN_HI32", Const, 0, ""},
		{"R_ALPHA_JMP_SLOT", Const, 0, ""},
		{"R_ALPHA_LITERAL", Const, 0, ""},
		{"R_ALPHA_LITUSE", Const, 0, ""},
		{"R_ALPHA_NONE", Const, 0, ""},
		{"R_ALPHA_OP_PRSHIFT", Const, 0, ""},
		{"R_ALPHA_OP_PSUB", Const, 0, ""},
		{"R_ALPHA_OP_PUSH", Const, 0, ""},
		{"R_ALPHA_OP_STORE", Const, 0, ""},
		{"R_ALPHA_REFLONG", Const, 0, ""},
		{"R_ALPHA_REFQUAD", Const, 0, ""},
		{"R_ALPHA_RELATIVE", Const, 0, ""},
		{"R_ALPHA_SREL16", Const, 0, ""},
		{"R_ALPHA_SREL32", Const, 0, ""},
		{"R_ALPHA_SREL64", Const, 0, ""},
		{"R_ARM", Type, 0, ""},
		{"R_ARM_ABS12", Const, 0, ""},
		{"R_ARM_ABS16", Const, 0, ""},
		{"R_ARM_ABS32", Const, 0, ""},
		{"R_ARM_ABS32_NOI", Const, 10, ""},
		{"R_ARM_ABS8", Const, 0, ""},
		{"R_ARM_ALU_PCREL_15_8", Const, 10, ""},
		{"R_ARM_ALU_PCREL_23_15", Const, 10, ""},
		{"R_ARM_ALU_PCREL_7_0", Const, 10, ""},
		{"R_ARM_ALU_PC_G0", Const, 10, ""},
		{"R_ARM_ALU_PC_G0_NC", Const, 10, ""},
		{"R_ARM_ALU_PC_G1", Const, 10, ""},
		{"R_ARM_ALU_PC_G1_NC", Const, 10, ""},
		{"R_ARM_ALU_PC_G2", Const, 10, ""},
		{"R_ARM_ALU_SBREL_19_12_NC", Const, 10, ""},
		{"R_ARM_ALU_SBREL_27_20_CK", Const, 10, ""},
		{"R_ARM_ALU_SB_G0", Const, 10, ""},
		{"R_ARM_ALU_SB_G0_NC", Const, 10, ""},
		{"R_ARM_ALU_SB_G1", Const, 10, ""},
		{"R_ARM_ALU_SB_G1_NC", Const, 10, ""},
		{"R_ARM_ALU_SB_G2", Const, 10, ""},
		{"R_ARM_AMP_VCALL9", Const, 0, ""},
		{"R_ARM_BASE_ABS", Const, 10, ""},
		{"R_ARM_CALL", Const, 10, ""},
		{"R_ARM_COPY", Const, 0, ""},
		{"R_ARM_GLOB_DAT", Const, 0, ""},
		{"R_ARM_GNU_VTENTRY", Const, 0, ""},
		{"R_ARM_GNU_VTINHERIT", Const, 0, ""},
		{"R_ARM_GOT32", Const, 0, ""},
		{"R_ARM_GOTOFF", Const, 0, ""},
		{"R_ARM_GOTOFF12", Const, 10, ""},
		{"R_ARM_GOTPC", Const, 0, ""},
		{"R_ARM_GOTRELAX", Const, 10, ""},
		{"R_ARM_GOT_ABS", Const, 10, ""},
		{"R_ARM_GOT_BREL12", Const, 10, ""},
		{"R_ARM_GOT_PREL", Const, 10, ""},
		{"R_ARM_IRELATIVE", Const, 10, ""},
		{"R_ARM_JUMP24", Const, 10, ""},
		{"R_ARM_JUMP_SLOT", Const, 0, ""},
		{"R_ARM_LDC_PC_G0", Const, 10, ""},
		{"R_ARM_LDC_PC_G1", Const, 10, ""},
		{"R_ARM_LDC_PC_G2", Const, 10, ""},
		{"R_ARM_LDC_SB_G0", Const, 10, ""},
		{"R_ARM_LDC_SB_G1", Const, 10, ""},
		{"R_ARM_LDC_SB_G2", Const, 10, ""},
		{"R_ARM_LDRS_PC_G0", Const, 10, ""},
		{"R_ARM_LDRS_PC_G1", Const, 10, ""},
		{"R_ARM_LDRS_PC_G2", Const, 10, ""},
		{"R_ARM_LDRS_SB_G0", Const, 10, ""},
		{"R_ARM_LDRS_SB_G1", Const, 10, ""},
		{"R_ARM_LDRS_SB_G2", Const, 10, ""},
		{"R_ARM_LDR_PC_G1", Const, 10, ""},
		{"R_ARM_LDR_PC_G2", Const, 10, ""},
		{"R_ARM_LDR_SBREL_11_10_NC", Const, 10, ""},
		{"R_ARM_LDR_SB_G0", Const, 10, ""},
		{"R_ARM_LDR_SB_G1", Const, 10, ""},
		{"R_ARM_LDR_SB_G2", Const, 10, ""},
		{"R_ARM_ME_TOO", Const, 10, ""},
		{"R_ARM_MOVT_ABS", Const, 10, ""},
		{"R_ARM_MOVT_BREL", Const, 10, ""},
		{"R_ARM_MOVT_PREL", Const, 10, ""},
		{"R_ARM_MOVW_ABS_NC", Const, 10, ""},
		{"R_ARM_MOVW_BREL", Const, 10, ""},
		{"R_ARM_MOVW_BREL_NC", Const, 10, ""},
		{"R_ARM_MOVW_PREL_NC", Const, 10, ""},
		{"R_ARM_NONE", Const, 0, ""},
		{"R_ARM_PC13", Const, 0, ""},
		{"R_ARM_PC24", Const, 0, ""},
		{"R_ARM_PLT32", Const, 0, ""},
		{"R_ARM_PLT32_ABS", Const, 10, ""},
		{"R_ARM_PREL31", Const, 10, ""},
		{"R_ARM_PRIVATE_0", Const, 10, ""},
		{"R_ARM_PRIVATE_1", Const, 10, ""},
		{"R_ARM_PRIVATE_10", Const, 10, ""},
		{"R_ARM_PRIVATE_11", Const, 10, ""},
		{"R_ARM_PRIVATE_12", Const, 10, ""},
		{"R_ARM_PRIVATE_13", Const, 10, ""},
		{"R_ARM_PRIVATE_14", Const, 10, ""},
		{"R_ARM_PRIVATE_15", Const, 10, ""},
		{"R_ARM_PRIVATE_2", Const, 10, ""},
		{"R_ARM_PRIVATE_3", Const, 10, ""},
		{"R_ARM_PRIVATE_4", Const, 10, ""},
		{"R_ARM_PRIVATE_5", Const, 10, ""},
		{"R_ARM_PRIVATE_6", Const, 10, ""},
		{"R_ARM_PRIVATE_7", Const, 10, ""},
		{"R_ARM_PRIVATE_8", Const, 10, ""},
		{"R_ARM_PRIVATE_9", Const, 10, ""},
		{"R_ARM_RABS32", Const, 0, ""},
		{"R_ARM_RBASE", Const, 0, ""},
		{"R_ARM_REL32", Const, 0, ""},
		{"R_ARM_REL32_NOI", Const, 10, ""},
		{"R_ARM_RELATIVE", Const, 0, ""},
		{"R_ARM_RPC24", Const, 0, ""},
		{"R_ARM_RREL32", Const, 0, ""},
		{"R_ARM_RSBREL32", Const, 0, ""},
		{"R_ARM_RXPC25", Const, 10, ""},
		{"R_ARM_SBREL31", Const, 10, ""},
		{"R_ARM_SBREL32", Const, 0, ""},
		{"R_ARM_SWI24", Const, 0, ""},
		{"R_ARM_TARGET1", Const, 10, ""},
		{"R_ARM_TARGET2", Const, 10, ""},
		{"R_ARM_THM_ABS5", Const, 0, ""},
		{"R_ARM_THM_ALU_ABS_G0_NC", Const, 10, ""},
		{"R_ARM_THM_ALU_ABS_G1_NC", Const, 10, ""},
		{"R_ARM_THM_ALU_ABS_G2_NC", Const, 10, ""},
		{"R_ARM_THM_ALU_ABS_G3", Const, 10, ""},
		{"R_ARM_THM_ALU_PREL_11_0", Const, 10, ""},
		{"R_ARM_THM_GOT_BREL12", Const, 10, ""},
		{"R_ARM_THM_JUMP11", Const, 10, ""},
		{"R_ARM_THM_JUMP19", Const, 10, ""},
		{"R_ARM_THM_JUMP24", Const, 10, ""},
		{"R_ARM_THM_JUMP6", Const, 10, ""},
		{"R_ARM_THM_JUMP8", Const, 10, ""},
		{"R_ARM_THM_MOVT_ABS", Const, 10, ""},
		{"R_ARM_THM_MOVT_BREL", Const, 10, ""},
		{"R_ARM_THM_MOVT_PREL", Const, 10, ""},
		{"R_ARM_THM_MOVW_ABS_NC", Const, 10, ""},
		{"R_ARM_THM_MOVW_BREL", Const, 10, ""},
		{"R_ARM_THM_MOVW_BREL_NC", Const, 10, ""},
		{"R_ARM_THM_MOVW_PREL_NC", Const, 10, ""},
		{"R_ARM_THM_PC12", Const, 10, ""},
		{"R_ARM_THM_PC22", Const, 0, ""},
		{"R_ARM_THM_PC8", Const, 0, ""},
		{"R_ARM_THM_RPC22", Const, 0, ""},
		{"R_ARM_THM_SWI8", Const, 0, ""},
		{"R_ARM_THM_TLS_CALL", Const, 10, ""},
		{"R_ARM_THM_TLS_DESCSEQ16", Const, 10, ""},
		{"R_ARM_THM_TLS_DESCSEQ32", Const, 10, ""},
		{"R_ARM_THM_XPC22", Const, 0, ""},
		{"R_ARM_TLS_CALL", Const, 10, ""},
		{"R_ARM_TLS_DESCSEQ", Const, 10, ""},
		{"R_ARM_TLS_DTPMOD32", Const, 10, ""},
		{"R_ARM_TLS_DTPOFF32", Const, 10, ""},
		{"R_ARM_TLS_GD32", Const, 10, ""},
		{"R_ARM_TLS_GOTDESC", Const, 10, ""},
		{"R_ARM_TLS_IE12GP", Const, 10, ""},
		{"R_ARM_TLS_IE32", Const, 10, ""},
		{"R_ARM_TLS_LDM32", Const, 10, ""},
		{"R_ARM_TLS_LDO12", Const, 10, ""},
		{"R_ARM_TLS_LDO32", Const, 10, ""},
		{"R_ARM_TLS_LE12", Const, 10, ""},
		{"R_ARM_TLS_LE32", Const, 10, ""},
		{"R_ARM_TLS_TPOFF32", Const, 10, ""},
		{"R_ARM_V4BX", Const, 10, ""},
		{"R_ARM_XPC25", Const, 0, ""},
		{"R_INFO", Func, 0, "func(sym uint32, typ uint32) uint64"},
		{"R_INFO32", Func, 0, "func(sym uint32, typ uint32) uint32"},
		{"R_LARCH", Type, 19, ""},
		{"R_LARCH_32", Const, 19, ""},
		{"R_LARCH_32_PCREL", Const, 20, ""},
		{"R_LARCH_64", Const, 19, ""},
		{"R_LARCH_64_PCREL", Const, 22, ""},
		{"R_LARCH_ABS64_HI12", Const, 20, ""},
		{"R_LARCH_ABS64_LO20", Const, 20, ""},
		{"R_LARCH_ABS_HI20", Const, 20, ""},
		{"R_LARCH_ABS_LO12", Const, 20, ""},
		{"R_LARCH_ADD16", Const, 19, ""},
		{"R_LARCH_ADD24", Const, 19, ""},
		{"R_LARCH_ADD32", Const, 19, ""},
		{"R_LARCH_ADD6", Const, 22, ""},
		{"R_LARCH_ADD64", Const, 19, ""},
		{"R_LARCH_ADD8", Const, 19, ""},
		{"R_LARCH_ADD_ULEB128", Const, 22, ""},
		{"R_LARCH_ALIGN", Const, 22, ""},
		{"R_LARCH_B16", Const, 20, ""},
		{"R_LARCH_B21", Const, 20, ""},
		{"R_LARCH_B26", Const, 20, ""},
		{"R_LARCH_CALL36", Const, 26, ""},
		{"R_LARCH_CFA", Const, 22, ""},
		{"R_LARCH_COPY", Const, 19, ""},
		{"R_LARCH_DELETE", Const, 22, ""},
		{"R_LARCH_GNU_VTENTRY", Const, 20, ""},
		{"R_LARCH_GNU_VTINHERIT", Const, 20, ""},
		{"R_LARCH_GOT64_HI12", Const, 20, ""},
		{"R_LARCH_GOT64_LO20", Const, 20, ""},
		{"R_LARCH_GOT64_PC_HI12", Const, 20, ""},
		{"R_LARCH_GOT64_PC_LO20", Const, 20, ""},
		{"R_LARCH_GOT_HI20", Const, 20, ""},
		{"R_LARCH_GOT_LO12", Const, 20, ""},
		{"R_LARCH_GOT_PC_HI20", Const, 20, ""},
		{"R_LARCH_GOT_PC_LO12", Const, 20, ""},
		{"R_LARCH_IRELATIVE", Const, 19, ""},
		{"R_LARCH_JUMP_SLOT", Const, 19, ""},
		{"R_LARCH_MARK_LA", Const, 19, ""},
		{"R_LARCH_MARK_PCREL", Const, 19, ""},
		{"R_LARCH_NONE", Const, 19, ""},
		{"R_LARCH_PCALA64_HI12", Const, 20, ""},
		{"R_LARCH_PCALA64_LO20", Const, 20, ""},
		{"R_LARCH_PCALA_HI20", Const, 20, ""},
		{"R_LARCH_PCALA_LO12", Const, 20, ""},
		{"R_LARCH_PCREL20_S2", Const, 22, ""},
		{"R_LARCH_RELATIVE", Const, 19, ""},
		{"R_LARCH_RELAX", Const, 20, ""},
		{"R_LARCH_SOP_ADD", Const, 19, ""},
		{"R_LARCH_SOP_AND", Const, 19, ""},
		{"R_LARCH_SOP_ASSERT", Const, 19, ""},
		{"R_LARCH_SOP_IF_ELSE", Const, 19, ""},
		{"R_LARCH_SOP_NOT", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_0_10_10_16_S2", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_0_5_10_16_S2", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_10_12", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_10_16", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_10_16_S2", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_10_5", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_S_5_20", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_U", Const, 19, ""},
		{"R_LARCH_SOP_POP_32_U_10_12", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_ABSOLUTE", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_DUP", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_GPREL", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_PCREL", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_PLT_PCREL", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_TLS_GD", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_TLS_GOT", Const, 19, ""},
		{"R_LARCH_SOP_PUSH_TLS_TPREL", Const, 19, ""},
		{"R_LARCH_SOP_SL", Const, 19, ""},
		{"R_LARCH_SOP_SR", Const, 19, ""},
		{"R_LARCH_SOP_SUB", Const, 19, ""},
		{"R_LARCH_SUB16", Const, 19, ""},
		{"R_LARCH_SUB24", Const, 19, ""},
		{"R_LARCH_SUB32", Const, 19, ""},
		{"R_LARCH_SUB6", Const, 22, ""},
		{"R_LARCH_SUB64", Const, 19, ""},
		{"R_LARCH_SUB8", Const, 19, ""},
		{"R_LARCH_SUB_ULEB128", Const, 22, ""},
		{"R_LARCH_TLS_DESC32", Const, 26, ""},
		{"R_LARCH_TLS_DESC64", Const, 26, ""},
		{"R_LARCH_TLS_DESC64_HI12", Const, 26, ""},
		{"R_LARCH_TLS_DESC64_LO20", Const, 26, ""},
		{"R_LARCH_TLS_DESC64_PC_HI12", Const, 26, ""},
		{"R_LARCH_TLS_DESC64_PC_LO20", Const, 26, ""},
		{"R_LARCH_TLS_DESC_CALL", Const, 26, ""},
		{"R_LARCH_TLS_DESC_HI20", Const, 26, ""},
		{"R_LARCH_TLS_DESC_LD", Const, 26, ""},
		{"R_LARCH_TLS_DESC_LO12", Const, 26, ""},
		{"R_LARCH_TLS_DESC_PCREL20_S2", Const, 26, ""},
		{"R_LARCH_TLS_DESC_PC_HI20", Const, 26, ""},
		{"R_LARCH_TLS_DESC_PC_LO12", Const, 26, ""},
		{"R_LARCH_TLS_DTPMOD32", Const, 19, ""},
		{"R_LARCH_TLS_DTPMOD64", Const, 19, ""},
		{"R_LARCH_TLS_DTPREL32", Const, 19, ""},
		{"R_LARCH_TLS_DTPREL64", Const, 19, ""},
		{"R_LARCH_TLS_GD_HI20", Const, 20, ""},
		{"R_LARCH_TLS_GD_PCREL20_S2", Const, 26, ""},
		{"R_LARCH_TLS_GD_PC_HI20", Const, 20, ""},
		{"R_LARCH_TLS_IE64_HI12", Const, 20, ""},
		{"R_LARCH_TLS_IE64_LO20", Const, 20, ""},
		{"R_LARCH_TLS_IE64_PC_HI12", Const, 20, ""},
		{"R_LARCH_TLS_IE64_PC_LO20", Const, 20, ""},
		{"R_LARCH_TLS_IE_HI20", Const, 20, ""},
		{"R_LARCH_TLS_IE_LO12", Const, 20, ""},
		{"R_LARCH_TLS_IE_PC_HI20", Const, 20, ""},
		{"R_LARCH_TLS_IE_PC_LO12", Const, 20, ""},
		{"R_LARCH_TLS_LD_HI20", Const, 20, ""},
		{"R_LARCH_TLS_LD_PCREL20_S2", Const, 26, ""},
		{"R_LARCH_TLS_LD_PC_HI20", Const, 20, ""},
		{"R_LARCH_TLS_LE64_HI12", Const, 20, ""},
		{"R_LARCH_TLS_LE64_LO20", Const, 20, ""},
		{"R_LARCH_TLS_LE_ADD_R", Const, 26, ""},
		{"R_LARCH_TLS_LE_HI20", Const, 20, ""},
		{"R_LARCH_TLS_LE_HI20_R", Const, 26, ""},
		{"R_LARCH_TLS_LE_LO12", Const, 20, ""},
		{"R_LARCH_TLS_LE_LO12_R", Const, 26, ""},
		{"R_LARCH_TLS_TPREL32", Const, 19, ""},
		{"R_LARCH_TLS_TPREL64", Const, 19, ""},
		{"R_MIPS", Type, 6, ""},
		{"R_MIPS_16", Const, 6, ""},
		{"R_MIPS_26", Const, 6, ""},
		{"R_MIPS_32", Const, 6, ""},
		{"R_MIPS_64", Const, 6, ""},
		{"R_MIPS_ADD_IMMEDIATE", Const, 6, ""},
		{"R_MIPS_CALL16", Const, 6, ""},
		{"R_MIPS_CALL_HI16", Const, 6, ""},
		{"R_MIPS_CALL_LO16", Const, 6, ""},
		{"R_MIPS_DELETE", Const, 6, ""},
		{"R_MIPS_GOT16", Const, 6, ""},
		{"R_MIPS_GOT_DISP", Const, 6, ""},
		{"R_MIPS_GOT_HI16", Const, 6, ""},
		{"R_MIPS_GOT_LO16", Const, 6, ""},
		{"R_MIPS_GOT_OFST", Const, 6, ""},
		{"R_MIPS_GOT_PAGE", Const, 6, ""},
		{"R_MIPS_GPREL16", Const, 6, ""},
		{"R_MIPS_GPREL32", Const, 6, ""},
		{"R_MIPS_HI16", Const, 6, ""},
		{"R_MIPS_HIGHER", Const, 6, ""},
		{"R_MIPS_HIGHEST", Const, 6, ""},
		{"R_MIPS_INSERT_A", Const, 6, ""},
		{"R_MIPS_INSERT_B", Const, 6, ""},
		{"R_MIPS_JALR", Const, 6, ""},
		{"R_MIPS_LITERAL", Const, 6, ""},
		{"R_MIPS_LO16", Const, 6, ""},
		{"R_MIPS_NONE", Const, 6, ""},
		{"R_MIPS_PC16", Const, 6, ""},
		{"R_MIPS_PC32", Const, 22, ""},
		{"R_MIPS_PJUMP", Const, 6, ""},
		{"R_MIPS_REL16", Const, 6, ""},
		{"R_MIPS_REL32", Const, 6, ""},
		{"R_MIPS_RELGOT", Const, 6, ""},
		{"R_MIPS_SCN_DISP", Const, 6, ""},
		{"R_MIPS_SHIFT5", Const, 6, ""},
		{"R_MIPS_SHIFT6", Const, 6, ""},
		{"R_MIPS_SUB", Const, 6, ""},
		{"R_MIPS_TLS_DTPMOD32", Const, 6, ""},
		{"R_MIPS_TLS_DTPMOD64", Const, 6, ""},
		{"R_MIPS_TLS_DTPREL32", Const, 6, ""},
		{"R_MIPS_TLS_DTPREL64", Const, 6, ""},
		{"R_MIPS_TLS_DTPREL_HI16", Const, 6, ""},
		{"R_MIPS_TLS_DTPREL_LO16", Const, 6, ""},
		{"R_MIPS_TLS_GD", Const, 6, ""},
		{"R_MIPS_TLS_GOTTPREL", Const, 6, ""},
		{"R_MIPS_TLS_LDM", Const, 6, ""},
		{"R_MIPS_TLS_TPREL32", Const, 6, ""},
		{"R_MIPS_TLS_TPREL64", Const, 6, ""},
		{"R_MIPS_TLS_TPREL_HI16", Const, 6, ""},
		{"R_MIPS_TLS_TPREL_LO16", Const, 6, ""},
		{"R_PPC", Type, 0, ""},
		{"R_PPC64", Type, 5, ""},
		{"R_PPC64_ADDR14", Const, 5, ""},
		{"R_PPC64_ADDR14_BRNTAKEN", Const, 5, ""},
		{"R_PPC64_ADDR14_BRTAKEN", Const, 5, ""},
		{"R_PPC64_ADDR16", Const, 5, ""},
		{"R_PPC64_ADDR16_DS", Const, 5, ""},
		{"R_PPC64_ADDR16_HA", Const, 5, ""},
		{"R_PPC64_ADDR16_HI", Const, 5, ""},
		{"R_PPC64_ADDR16_HIGH", Const, 10, ""},
		{"R_PPC64_ADDR16_HIGHA", Const, 10, ""},
		{"R_PPC64_ADDR16_HIGHER", Const, 5, ""},
		{"R_PPC64_ADDR16_HIGHER34", Const, 20, ""},
		{"R_PPC64_ADDR16_HIGHERA", Const, 5, ""},
		{"R_PPC64_ADDR16_HIGHERA34", Const, 20, ""},
		{"R_PPC64_ADDR16_HIGHEST", Const, 5, ""},
		{"R_PPC64_ADDR16_HIGHEST34", Const, 20, ""},
		{"R_PPC64_ADDR16_HIGHESTA", Const, 5, ""},
		{"R_PPC64_ADDR16_HIGHESTA34", Const, 20, ""},
		{"R_PPC64_ADDR16_LO", Const, 5, ""},
		{"R_PPC64_ADDR16_LO_DS", Const, 5, ""},
		{"R_PPC64_ADDR24", Const, 5, ""},
		{"R_PPC64_ADDR32", Const, 5, ""},
		{"R_PPC64_ADDR64", Const, 5, ""},
		{"R_PPC64_ADDR64_LOCAL", Const, 10, ""},
		{"R_PPC64_COPY", Const, 20, ""},
		{"R_PPC64_D28", Const, 20, ""},
		{"R_PPC64_D34", Const, 20, ""},
		{"R_PPC64_D34_HA30", Const, 20, ""},
		{"R_PPC64_D34_HI30", Const, 20, ""},
		{"R_PPC64_D34_LO", Const, 20, ""},
		{"R_PPC64_DTPMOD64", Const, 5, ""},
		{"R_PPC64_DTPREL16", Const, 5, ""},
		{"R_PPC64_DTPREL16_DS", Const, 5, ""},
		{"R_PPC64_DTPREL16_HA", Const, 5, ""},
		{"R_PPC64_DTPREL16_HI", Const, 5, ""},
		{"R_PPC64_DTPREL16_HIGH", Const, 10, ""},
		{"R_PPC64_DTPREL16_HIGHA", Const, 10, ""},
		{"R_PPC64_DTPREL16_HIGHER", Const, 5, ""},
		{"R_PPC64_DTPREL16_HIGHERA", Const, 5, ""},
		{"R_PPC64_DTPREL16_HIGHEST", Const, 5, ""},
		{"R_PPC64_DTPREL16_HIGHESTA", Const, 5, ""},
		{"R_PPC64_DTPREL16_LO", Const, 5, ""},
		{"R_PPC64_DTPREL16_LO_DS", Const, 5, ""},
		{"R_PPC64_DTPREL34", Const, 20, ""},
		{"R_PPC64_DTPREL64", Const, 5, ""},
		{"R_PPC64_ENTRY", Const, 10, ""},
		{"R_PPC64_GLOB_DAT", Const, 20, ""},
		{"R_PPC64_GNU_VTENTRY", Const, 20, ""},
		{"R_PPC64_GNU_VTINHERIT", Const, 20, ""},
		{"R_PPC64_GOT16", Const, 5, ""},
		{"R_PPC64_GOT16_DS", Const, 5, ""},
		{"R_PPC64_GOT16_HA", Const, 5, ""},
		{"R_PPC64_GOT16_HI", Const, 5, ""},
		{"R_PPC64_GOT16_LO", Const, 5, ""},
		{"R_PPC64_GOT16_LO_DS", Const, 5, ""},
		{"R_PPC64_GOT_DTPREL16_DS", Const, 5, ""},
		{"R_PPC64_GOT_DTPREL16_HA", Const, 5, ""},
		{"R_PPC64_GOT_DTPREL16_HI", Const, 5, ""},
		{"R_PPC64_GOT_DTPREL16_LO_DS", Const, 5, ""},
		{"R_PPC64_GOT_DTPREL_PCREL34", Const, 20, ""},
		{"R_PPC64_GOT_PCREL34", Const, 20, ""},
		{"R_PPC64_GOT_TLSGD16", Const, 5, ""},
		{"R_PPC64_GOT_TLSGD16_HA", Const, 5, ""},
		{"R_PPC64_GOT_TLSGD16_HI", Const, 5, ""},
		{"R_PPC64_GOT_TLSGD16_LO", Const, 5, ""},
		{"R_PPC64_GOT_TLSGD_PCREL34", Const, 20, ""},
		{"R_PPC64_GOT_TLSLD16", Const, 5, ""},
		{"R_PPC64_GOT_TLSLD16_HA", Const, 5, ""},
		{"R_PPC64_GOT_TLSLD16_HI", Const, 5, ""},
		{"R_PPC64_GOT_TLSLD16_LO", Const, 5, ""},
		{"R_PPC64_GOT_TLSLD_PCREL34", Const, 20, ""},
		{"R_PPC64_GOT_TPREL16_DS", Const, 5, ""},
		{"R_PPC64_GOT_TPREL16_HA", Const, 5, ""},
		{"R_PPC64_GOT_TPREL16_HI", Const, 5, ""},
		{"R_PPC64_GOT_TPREL16_LO_DS", Const, 5, ""},
		{"R_PPC64_GOT_TPREL_PCREL34", Const, 20, ""},
		{"R_PPC64_IRELATIVE", Const, 10, ""},
		{"R_PPC64_JMP_IREL", Const, 10, ""},
		{"R_PPC64_JMP_SLOT", Const, 5, ""},
		{"R_PPC64_NONE", Const, 5, ""},
		{"R_PPC64_PCREL28", Const, 20, ""},
		{"R_PPC64_PCREL34", Const, 20, ""},
		{"R_PPC64_PCREL_OPT", Const, 20, ""},
		{"R_PPC64_PLT16_HA", Const, 20, ""},
		{"R_PPC64_PLT16_HI", Const, 20, ""},
		{"R_PPC64_PLT16_LO", Const, 20, ""},
		{"R_PPC64_PLT16_LO_DS", Const, 10, ""},
		{"R_PPC64_PLT32", Const, 20, ""},
		{"R_PPC64_PLT64", Const, 20, ""},
		{"R_PPC64_PLTCALL", Const, 20, ""},
		{"R_PPC64_PLTCALL_NOTOC", Const, 20, ""},
		{"R_PPC64_PLTGOT16", Const, 10, ""},
		{"R_PPC64_PLTGOT16_DS", Const, 10, ""},
		{"R_PPC64_PLTGOT16_HA", Const, 10, ""},
		{"R_PPC64_PLTGOT16_HI", Const, 10, ""},
		{"R_PPC64_PLTGOT16_LO", Const, 10, ""},
		{"R_PPC64_PLTGOT_LO_DS", Const, 10, ""},
		{"R_PPC64_PLTREL32", Const, 20, ""},
		{"R_PPC64_PLTREL64", Const, 20, ""},
		{"R_PPC64_PLTSEQ", Const, 20, ""},
		{"R_PPC64_PLTSEQ_NOTOC", Const, 20, ""},
		{"R_PPC64_PLT_PCREL34", Const, 20, ""},
		{"R_PPC64_PLT_PCREL34_NOTOC", Const, 20, ""},
		{"R_PPC64_REL14", Const, 5, ""},
		{"R_PPC64_REL14_BRNTAKEN", Const, 5, ""},
		{"R_PPC64_REL14_BRTAKEN", Const, 5, ""},
		{"R_PPC64_REL16", Const, 5, ""},
		{"R_PPC64_REL16DX_HA", Const, 10, ""},
		{"R_PPC64_REL16_HA", Const, 5, ""},
		{"R_PPC64_REL16_HI", Const, 5, ""},
		{"R_PPC64_REL16_HIGH", Const, 20, ""},
		{"R_PPC64_REL16_HIGHA", Const, 20, ""},
		{"R_PPC64_REL16_HIGHER", Const, 20, ""},
		{"R_PPC64_REL16_HIGHER34", Const, 20, ""},
		{"R_PPC64_REL16_HIGHERA", Const, 20, ""},
		{"R_PPC64_REL16_HIGHERA34", Const, 20, ""},
		{"R_PPC64_REL16_HIGHEST", Const, 20, ""},
		{"R_PPC64_REL16_HIGHEST34", Const, 20, ""},
		{"R_PPC64_REL16_HIGHESTA", Const, 20, ""},
		{"R_PPC64_REL16_HIGHESTA34", Const, 20, ""},
		{"R_PPC64_REL16_LO", Const, 5, ""},
		{"R_PPC64_REL24", Const, 5, ""},
		{"R_PPC64_REL24_NOTOC", Const, 10, ""},
		{"R_PPC64_REL24_P9NOTOC", Const, 21, ""},
		{"R_PPC64_REL30", Const, 20, ""},
		{"R_PPC64_REL32", Const, 5, ""},
		{"R_PPC64_REL64", Const, 5, ""},
		{"R_PPC64_RELATIVE", Const, 18, ""},
		{"R_PPC64_SECTOFF", Const, 20, ""},
		{"R_PPC64_SECTOFF_DS", Const, 10, ""},
		{"R_PPC64_SECTOFF_HA", Const, 20, ""},
		{"R_PPC64_SECTOFF_HI", Const, 20, ""},
		{"R_PPC64_SECTOFF_LO", Const, 20, ""},
		{"R_PPC64_SECTOFF_LO_DS", Const, 10, ""},
		{"R_PPC64_TLS", Const, 5, ""},
		{"R_PPC64_TLSGD", Const, 5, ""},
		{"R_PPC64_TLSLD", Const, 5, ""},
		{"R_PPC64_TOC", Const, 5, ""},
		{"R_PPC64_TOC16", Const, 5, ""},
		{"R_PPC64_TOC16_DS", Const, 5, ""},
		{"R_PPC64_TOC16_HA", Const, 5, ""},
		{"R_PPC64_TOC16_HI", Const, 5, ""},
		{"R_PPC64_TOC16_LO", Const, 5, ""},
		{"R_PPC64_TOC16_LO_DS", Const, 5, ""},
		{"R_PPC64_TOCSAVE", Const, 10, ""},
		{"R_PPC64_TPREL16", Const, 5, ""},
		{"R_PPC64_TPREL16_DS", Const, 5, ""},
		{"R_PPC64_TPREL16_HA", Const, 5, ""},
		{"R_PPC64_TPREL16_HI", Const, 5, ""},
		{"R_PPC64_TPREL16_HIGH", Const, 10, ""},
		{"R_PPC64_TPREL16_HIGHA", Const, 10, ""},
		{"R_PPC64_TPREL16_HIGHER", Const, 5, ""},
		{"R_PPC64_TPREL16_HIGHERA", Const, 5, ""},
		{"R_PPC64_TPREL16_HIGHEST", Const, 5, ""},
		{"R_PPC64_TPREL16_HIGHESTA", Const, 5, ""},
		{"R_PPC64_TPREL16_LO", Const, 5, ""},
		{"R_PPC64_TPREL16_LO_DS", Const, 5, ""},
		{"R_PPC64_TPREL34", Const, 20, ""},
		{"R_PPC64_TPREL64", Const, 5, ""},
		{"R_PPC64_UADDR16", Const, 20, ""},
		{"R_PPC64_UADDR32", Const, 20, ""},
		{"R_PPC64_UADDR64", Const, 20, ""},
		{"R_PPC_ADDR14", Const, 0, ""},
		{"R_PPC_ADDR14_BRNTAKEN", Const, 0, ""},
		{"R_PPC_ADDR14_BRTAKEN", Const, 0, ""},
		{"R_PPC_ADDR16", Const, 0, ""},
		{"R_PPC_ADDR16_HA", Const, 0, ""},
		{"R_PPC_ADDR16_HI", Const, 0, ""},
		{"R_PPC_ADDR16_LO", Const, 0, ""},
		{"R_PPC_ADDR24", Const, 0, ""},
		{"R_PPC_ADDR32", Const, 0, ""},
		{"R_PPC_COPY", Const, 0, ""},
		{"R_PPC_DTPMOD32", Const, 0, ""},
		{"R_PPC_DTPREL16", Const, 0, ""},
		{"R_PPC_DTPREL16_HA", Const, 0, ""},
		{"R_PPC_DTPREL16_HI", Const, 0, ""},
		{"R_PPC_DTPREL16_LO", Const, 0, ""},
		{"R_PPC_DTPREL32", Const, 0, ""},
		{"R_PPC_EMB_BIT_FLD", Const, 0, ""},
		{"R_PPC_EMB_MRKREF", Const, 0, ""},
		{"R_PPC_EMB_NADDR16", Const, 0, ""},
		{"R_PPC_EMB_NADDR16_HA", Const, 0, ""},
		{"R_PPC_EMB_NADDR16_HI", Const, 0, ""},
		{"R_PPC_EMB_NADDR16_LO", Const, 0, ""},
		{"R_PPC_EMB_NADDR32", Const, 0, ""},
		{"R_PPC_EMB_RELSDA", Const, 0, ""},
		{"R_PPC_EMB_RELSEC16", Const, 0, ""},
		{"R_PPC_EMB_RELST_HA", Const, 0, ""},
		{"R_PPC_EMB_RELST_HI", Const, 0, ""},
		{"R_PPC_EMB_RELST_LO", Const, 0, ""},
		{"R_PPC_EMB_SDA21", Const, 0, ""},
		{"R_PPC_EMB_SDA2I16", Const, 0, ""},
		{"R_PPC_EMB_SDA2REL", Const, 0, ""},
		{"R_PPC_EMB_SDAI16", Const, 0, ""},
		{"R_PPC_GLOB_DAT", Const, 0, ""},
		{"R_PPC_GOT16", Const, 0, ""},
		{"R_PPC_GOT16_HA", Const, 0, ""},
		{"R_PPC_GOT16_HI", Const, 0, ""},
		{"R_PPC_GOT16_LO", Const, 0, ""},
		{"R_PPC_GOT_TLSGD16", Const, 0, ""},
		{"R_PPC_GOT_TLSGD16_HA", Const, 0, ""},
		{"R_PPC_GOT_TLSGD16_HI", Const, 0, ""},
		{"R_PPC_GOT_TLSGD16_LO", Const, 0, ""},
		{"R_PPC_GOT_TLSLD16", Const, 0, ""},
		{"R_PPC_GOT_TLSLD16_HA", Const, 0, ""},
		{"R_PPC_GOT_TLSLD16_HI", Const, 0, ""},
		{"R_PPC_GOT_TLSLD16_LO", Const, 0, ""},
		{"R_PPC_GOT_TPREL16", Const, 0, ""},
		{"R_PPC_GOT_TPREL16_HA", Const, 0, ""},
		{"R_PPC_GOT_TPREL16_HI", Const, 0, ""},
		{"R_PPC_GOT_TPREL16_LO", Const, 0, ""},
		{"R_PPC_JMP_SLOT", Const, 0, ""},
		{"R_PPC_LOCAL24PC", Const, 0, ""},
		{"R_PPC_NONE", Const, 0, ""},
		{"R_PPC_PLT16_HA", Const, 0, ""},
		{"R_PPC_PLT16_HI", Const, 0, ""},
		{"R_PPC_PLT16_LO", Const, 0, ""},
		{"R_PPC_PLT32", Const, 0, ""},
		{"R_PPC_PLTREL24", Const, 0, ""},
		{"R_PPC_PLTREL32", Const, 0, ""},
		{"R_PPC_REL14", Const, 0, ""},
		{"R_PPC_REL14_BRNTAKEN", Const, 0, ""},
		{"R_PPC_REL14_BRTAKEN", Const, 0, ""},
		{"R_PPC_REL24", Const, 0, ""},
		{"R_PPC_REL32", Const, 0, ""},
		{"R_PPC_RELATIVE", Const, 0, ""},
		{"R_PPC_SDAREL16", Const, 0, ""},
		{"R_PPC_SECTOFF", Const, 0, ""},
		{"R_PPC_SECTOFF_HA", Const, 0, ""},
		{"R_PPC_SECTOFF_HI", Const, 0, ""},
		{"R_PPC_SECTOFF_LO", Const, 0, ""},
		{"R_PPC_TLS", Const, 0, ""},
		{"R_PPC_TPREL16", Const, 0, ""},
		{"R_PPC_TPREL16_HA", Const, 0, ""},
		{"R_PPC_TPREL16_HI", Const, 0, ""},
		{"R_PPC_TPREL16_LO", Const, 0, ""},
		{"R_PPC_TPREL32", Const, 0, ""},
		{"R_PPC_UADDR16", Const, 0, ""},
		{"R_PPC_UADDR32", Const, 0, ""},
		{"R_RISCV", Type, 11, ""},
		{"R_RISCV_32", Const, 11, ""},
		{"R_RISCV_32_PCREL", Const, 12, ""},
		{"R_RISCV_64", Const, 11, ""},
		{"R_RISCV_ADD16", Const, 11, ""},
		{"R_RISCV_ADD32", Const, 11, ""},
		{"R_RISCV_ADD64", Const, 11, ""},
		{"R_RISCV_ADD8", Const, 11, ""},
		{"R_RISCV_ALIGN", Const, 11, ""},
		{"R_RISCV_BRANCH", Const, 11, ""},
		{"R_RISCV_CALL", Const, 11, ""},
		{"R_RISCV_CALL_PLT", Const, 11, ""},
		{"R_RISCV_COPY", Const, 11, ""},
		{"R_RISCV_GNU_VTENTRY", Const, 11, ""},
		{"R_RISCV_GNU_VTINHERIT", Const, 11, ""},
		{"R_RISCV_GOT_HI20", Const, 11, ""},
		{"R_RISCV_GPREL_I", Const, 11, ""},
		{"R_RISCV_GPREL_S", Const, 11, ""},
		{"R_RISCV_HI20", Const, 11, ""},
		{"R_RISCV_JAL", Const, 11, ""},
		{"R_RISCV_JUMP_SLOT", Const, 11, ""},
		{"R_RISCV_LO12_I", Const, 11, ""},
		{"R_RISCV_LO12_S", Const, 11, ""},
		{"R_RISCV_NONE", Const, 11, ""},
		{"R_RISCV_PCREL_HI20", Const, 11, ""},
		{"R_RISCV_PCREL_LO12_I", Const, 11, ""},
		{"R_RISCV_PCREL_LO12_S", Const, 11, ""},
		{"R_RISCV_RELATIVE", Const, 11, ""},
		{"R_RISCV_RELAX", Const, 11, ""},
		{"R_RISCV_RVC_BRANCH", Const, 11, ""},
		{"R_RISCV_RVC_JUMP", Const, 11, ""},
		{"R_RISCV_RVC_LUI", Const, 11, ""},
		{"R_RISCV_SET16", Const, 11, ""},
		{"R_RISCV_SET32", Const, 11, ""},
		{"R_RISCV_SET6", Const, 11, ""},
		{"R_RISCV_SET8", Const, 11, ""},
		{"R_RISCV_SUB16", Const, 11, ""},
		{"R_RISCV_SUB32", Const, 11, ""},
		{"R_RISCV_SUB6", Const, 11, ""},
		{"R_RISCV_SUB64", Const, 11, ""},
		{"R_RISCV_SUB8", Const, 11, ""},
		{"R_RISCV_TLS_DTPMOD32", Const, 11, ""},
		{"R_RISCV_TLS_DTPMOD64", Const, 11, ""},
		{"R_RISCV_TLS_DTPREL32", Const, 11, ""},
		{"R_RISCV_TLS_DTPREL64", Const, 11, ""},
		{"R_RISCV_TLS_GD_HI20", Const, 11, ""},
		{"R_RISCV_TLS_GOT_HI20", Const, 11, ""},
		{"R_RISCV_TLS_TPREL32", Const, 11, ""},
		{"R_RISCV_TLS_TPREL64", Const, 11, ""},
		{"R_RISCV_TPREL_ADD", Const, 11, ""},
		{"R_RISCV_TPREL_HI20", Const, 11, ""},
		{"R_RISCV_TPREL_I", Const, 11, ""},
		{"R_RISCV_TPREL_LO12_I", Const, 11, ""},
		{"R_RISCV_TPREL_LO12_S", Const, 11, ""},
		{"R_RISCV_TPREL_S", Const, 11, ""},
		{"R_SPARC", Type, 0, ""},
		{"R_SPARC_10", Const, 0, ""},
		{"R_SPARC_11", Const, 0, ""},
		{"R_SPARC_13", Const, 0, ""},
		{"R_SPARC_16", Const, 0, ""},
		{"R_SPARC_22", Const, 0, ""},
		{"R_SPARC_32", Const, 0, ""},
		{"R_SPARC_5", Const, 0, ""},
		{"R_SPARC_6", Const, 0, ""},
		{"R_SPARC_64", Const, 0, ""},
		{"R_SPARC_7", Const, 0, ""},
		{"R_SPARC_8", Const, 0, ""},
		{"R_SPARC_COPY", Const, 0, ""},
		{"R_SPARC_DISP16", Const, 0, ""},
		{"R_SPARC_DISP32", Const, 0, ""},
		{"R_SPARC_DISP64", Const, 0, ""},
		{"R_SPARC_DISP8", Const, 0, ""},
		{"R_SPARC_GLOB_DAT", Const, 0, ""},
		{"R_SPARC_GLOB_JMP", Const, 0, ""},
		{"R_SPARC_GOT10", Const, 0, ""},
		{"R_SPARC_GOT13", Const, 0, ""},
		{"R_SPARC_GOT22", Const, 0, ""},
		{"R_SPARC_H44", Const, 0, ""},
		{"R_SPARC_HH22", Const, 0, ""},
		{"R_SPARC_HI22", Const, 0, ""},
		{"R_SPARC_HIPLT22", Const, 0, ""},
		{"R_SPARC_HIX22", Const, 0, ""},
		{"R_SPARC_HM10", Const, 0, ""},
		{"R_SPARC_JMP_SLOT", Const, 0, ""},
		{"R_SPARC_L44", Const, 0, ""},
		{"R_SPARC_LM22", Const, 0, ""},
		{"R_SPARC_LO10", Const, 0, ""},
		{"R_SPARC_LOPLT10", Const, 0, ""},
		{"R_SPARC_LOX10", Const, 0, ""},
		{"R_SPARC_M44", Const, 0, ""},
		{"R_SPARC_NONE", Const, 0, ""},
		{"R_SPARC_OLO10", Const, 0, ""},
		{"R_SPARC_PC10", Const, 0, ""},
		{"R_SPARC_PC22", Const, 0, ""},
		{"R_SPARC_PCPLT10", Const, 0, ""},
		{"R_SPARC_PCPLT22", Const, 0, ""},
		{"R_SPARC_PCPLT32", Const, 0, ""},
		{"R_SPARC_PC_HH22", Const, 0, ""},
		{"R_SPARC_PC_HM10", Const, 0, ""},
		{"R_SPARC_PC_LM22", Const, 0, ""},
		{"R_SPARC_PLT32", Const, 0, ""},
		{"R_SPARC_PLT64", Const, 0, ""},
		{"R_SPARC_REGISTER", Const, 0, ""},
		{"R_SPARC_RELATIVE", Const, 0, ""},
		{"R_SPARC_UA16", Const, 0, ""},
		{"R_SPARC_UA32", Const, 0, ""},
		{"R_SPARC_UA64", Const, 0, ""},
		{"R_SPARC_WDISP16", Const, 0, ""},
		{"R_SPARC_WDISP19", Const, 0, ""},
		{"R_SPARC_WDISP22", Const, 0, ""},
		{"R_SPARC_WDISP30", Const, 0, ""},
		{"R_SPARC_WPLT30", Const, 0, ""},
		{"R_SYM32", Func, 0, "func(info uint32) uint32"},
		{"R_SYM64", Func, 0, "func(info uint64) uint32"},
		{"R_TYPE32", Func, 0, "func(info uint32) uint32"},
		{"R_TYPE64", Func, 0, "func(info uint64) uint32"},
		{"R_X86_64", Type, 0, ""},
		{"R_X86_64_16", Const, 0, ""},
		{"R_X86_64_32", Const, 0, ""},
		{"R_X86_64_32S", Const, 0, ""},
		{"R_X86_64_64", Const, 0, ""},
		{"R_X86_64_8", Const, 0, ""},
		{"R_X86_64_COPY", Const, 0, ""},
		{"R_X86_64_DTPMOD64", Const, 0, ""},
		{"R_X86_64_DTPOFF32", Const, 0, ""},
		{"R_X86_64_DTPOFF64", Const, 0, ""},
		{"R_X86_64_GLOB_DAT", Const, 0, ""},
		{"R_X86_64_GOT32", Const, 0, ""},
		{"R_X86_64_GOT64", Const, 10, ""},
		{"R_X86_64_GOTOFF64", Const, 10, ""},
		{"R_X86_64_GOTPC32", Const, 10, ""},
		{"R_X86_64_GOTPC32_TLSDESC", Const, 10, ""},
		{"R_X86_64_GOTPC64", Const, 10, ""},
		{"R_X86_64_GOTPCREL", Const, 0, ""},
		{"R_X86_64_GOTPCREL64", Const, 10, ""},
		{"R_X86_64_GOTPCRELX", Const, 10, ""},
		{"R_X86_64_GOTPLT64", Const, 10, ""},
		{"R_X86_64_GOTTPOFF", Const, 0, ""},
		{"R_X86_64_IRELATIVE", Const, 10, ""},
		{"R_X86_64_JMP_SLOT", Const, 0, ""},
		{"R_X86_64_NONE", Const, 0, ""},
		{"R_X86_64_PC16", Const, 0, ""},
		{"R_X86_64_PC32", Const, 0, ""},
		{"R_X86_64_PC32_BND", Const, 10, ""},
		{"R_X86_64_PC64", Const, 10, ""},
		{"R_X86_64_PC8", Const, 0, ""},
		{"R_X86_64_PLT32", Const, 0, ""},
		{"R_X86_64_PLT32_BND", Const, 10, ""},
		{"R_X86_64_PLTOFF64", Const, 10, ""},
		{"R_X86_64_RELATIVE", Const, 0, ""},
		{"R_X86_64_RELATIVE64", Const, 10, ""},
		{"R_X86_64_REX_GOTPCRELX", Const, 10, ""},
		{"R_X86_64_SIZE32", Const, 10, ""},
		{"R_X86_64_SIZE64", Const, 10, ""},
		{"R_X86_64_TLSDESC", Const, 10, ""},
		{"R_X86_64_TLSDESC_CALL", Const, 10, ""},
		{"R_X86_64_TLSGD", Const, 0, ""},
		{"R_X86_64_TLSLD", Const, 0, ""},
		{"R_X86_64_TPOFF32", Const, 0, ""},
		{"R_X86_64_TPOFF64", Const, 0, ""},
		{"Rel32", Type, 0, ""},
		{"Rel32.Info", Field, 0, ""},
		{"Rel32.Off", Field, 0, ""},
		{"Rel64", Type, 0, ""},
		{"Rel64.Info", Field, 0, ""},
		{"Rel64.Off", Field, 0, ""},
		{"Rela32", Type, 0, ""},
		{"Rela32.Addend", Field, 0, ""},
		{"Rela32.Info", Field, 0, ""},
		{"Rela32.Off", Field, 0, ""},
		{"Rela64", Type, 0, ""},
		{"Rela64.Addend", Field, 0, ""},
		{"Rela64.Info", Field, 0, ""},
		{"Rela64.Off", Field, 0, ""},
		{"SHF_ALLOC", Const, 0, ""},
		{"SHF_COMPRESSED", Const, 6, ""},
		{"SHF_EXECINSTR", Const, 0, ""},
		{"SHF_GROUP", Const, 0, ""},
		{"SHF_INFO_LINK", Const, 0, ""},
		{"SHF_LINK_ORDER", Const, 0, ""},
		{"SHF_MASKOS", Const, 0, ""},
		{"SHF_MASKPROC", Const, 0, ""},
		{"SHF_MERGE", Const, 0, ""},
		{"SHF_OS_NONCONFORMING", Const, 0, ""},
		{"SHF_STRINGS", Const, 0, ""},
		{"SHF_TLS", Const, 0, ""},
		{"SHF_WRITE", Const, 0, ""},
		{"SHN_ABS", Const, 0, ""},
		{"SHN_COMMON", Const, 0, ""},
		{"SHN_HIOS", Const, 0, ""},
		{"SHN_HIPROC", Const, 0, ""},
		{"SHN_HIRESERVE", Const, 0, ""},
		{"SHN_LOOS", Const, 0, ""},
		{"SHN_LOPROC", Const, 0, ""},
		{"SHN_LORESERVE", Const, 0, ""},
		{"SHN_UNDEF", Const, 0, ""},
		{"SHN_XINDEX", Const, 0, ""},
		{"SHT_DYNAMIC", Const, 0, ""},
		{"SHT_DYNSYM", Const, 0, ""},
		{"SHT_FINI_ARRAY", Const, 0, ""},
		{"SHT_GNU_ATTRIBUTES", Const, 0, ""},
		{"SHT_GNU_HASH", Const, 0, ""},
		{"SHT_GNU_LIBLIST", Const, 0, ""},
		{"SHT_GNU_VERDEF", Const, 0, ""},
		{"SHT_GNU_VERNEED", Const, 0, ""},
		{"SHT_GNU_VERSYM", Const, 0, ""},
		{"SHT_GROUP", Const, 0, ""},
		{"SHT_HASH", Const, 0, ""},
		{"SHT_HIOS", Const, 0, ""},
		{"SHT_HIPROC", Const, 0, ""},
		{"SHT_HIUSER", Const, 0, ""},
		{"SHT_INIT_ARRAY", Const, 0, ""},
		{"SHT_LOOS", Const, 0, ""},
		{"SHT_LOPROC", Const, 0, ""},
		{"SHT_LOUSER", Const, 0, ""},
		{"SHT_MIPS_ABIFLAGS", Const, 17, ""},
		{"SHT_NOBITS", Const, 0, ""},
		{"SHT_NOTE", Const, 0, ""},
		{"SHT_NULL", Const, 0, ""},
		{"SHT_PREINIT_ARRAY", Const, 0, ""},
		{"SHT_PROGBITS", Const, 0, ""},
		{"SHT_REL", Const, 0, ""},
		{"SHT_RELA", Const, 0, ""},
		{"SHT_RISCV_ATTRIBUTES", Const, 25, ""},
		{"SHT_SHLIB", Const, 0, ""},
		{"SHT_STRTAB", Const, 0, ""},
		{"SHT_SYMTAB", Const, 0, ""},
		{"SHT_SYMTAB_SHNDX", Const, 0, ""},
		{"STB_GLOBAL", Const, 0, ""},
		{"STB_HIOS", Const, 0, ""},
		{"STB_HIPROC", Const, 0, ""},
		{"STB_LOCAL", Const, 0, ""},
		{"STB_LOOS", Const, 0, ""},
		{"STB_LOPROC", Const, 0, ""},
		{"STB_WEAK", Const, 0, ""},
		{"STT_COMMON", Const, 0, ""},
		{"STT_FILE", Const, 0, ""},
		{"STT_FUNC", Const, 0, ""},
		{"STT_GNU_IFUNC", Const, 23, ""},
		{"STT_HIOS", Const, 0, ""},
		{"STT_HIPROC", Const, 0, ""},
		{"STT_LOOS", Const, 0, ""},
		{"STT_LOPROC", Const, 0, ""},
		{"STT_NOTYPE", Const, 0, ""},
		{"STT_OBJECT", Const, 0, ""},
		{"STT_RELC", Const, 23, ""},
		{"STT_SECTION", Const, 0, ""},
		{"STT_SRELC", Const, 23, ""},
		{"STT_TLS", Const, 0, ""},
		{"STV_DEFAULT", Const, 0, ""},
		{"STV_HIDDEN", Const, 0, ""},
		{"STV_INTERNAL", Const, 0, ""},
		{"STV_PROTECTED", Const, 0, ""},
		{"ST_BIND", Func, 0, "func(info uint8) SymBind"},
		{"ST_INFO", Func, 0, "func(bind SymBind, typ SymType) uint8"},
		{"ST_TYPE", Func, 0, "func(info uint8) SymType"},
		{"ST_VISIBILITY", Func, 0, "func(other uint8) SymVis"},
		{"Section", Type, 0, ""},
		{"Section.ReaderAt", Field, 0, ""},
		{"Section.SectionHeader", Field, 0, ""},
		{"Section32", Type, 0, ""},
		{"Section32.Addr", Field, 0, ""},
		{"Section32.Addralign", Field, 0, ""},
		{"Section32.Entsize", Field, 0, ""},
		{"Section32.Flags", Field, 0, ""},
		{"Section32.Info", Field, 0, ""},
		{"Section32.Link", Field, 0, ""},
		{"Section32.Name", Field, 0, ""},
		{"Section32.Off", Field, 0, ""},
		{"Section32.Size", Field, 0, ""},
		{"Section32.Type", Field, 0, ""},
		{"Section64", Type, 0, ""},
		{"Section64.Addr", Field, 0, ""},
		{"Section64.Addralign", Field, 0, ""},
		{"Section64.Entsize", Field, 0, ""},
		{"Section64.Flags", Field, 0, ""},
		{"Section64.Info", Field, 0, ""},
		{"Section64.Link", Field, 0, ""},
		{"Section64.Name", Field, 0, ""},
		{"Section64.Off", Field, 0, ""},
		{"Section64.Size", Field, 0, ""},
		{"Section64.Type", Field, 0, ""},
		{"SectionFlag", Type, 0, ""},
		{"SectionHeader", Type, 0, ""},
		{"SectionHeader.Addr", Field, 0, ""},
		{"SectionHeader.Addralign", Field, 0, ""},
		{"SectionHeader.Entsize", Field, 0, ""},
		{"SectionHeader.FileSize", Field, 6, ""},
		{"SectionHeader.Flags", Field, 0, ""},
		{"SectionHeader.Info", Field, 0, ""},
		{"SectionHeader.Link", Field, 0, ""},
		{"SectionHeader.Name", Field, 0, ""},
		{"SectionHeader.Offset", Field, 0, ""},
		{"SectionHeader.Size", Field, 0, ""},
		{"SectionHeader.Type", Field, 0, ""},
		{"SectionIndex", Type, 0, ""},
		{"SectionType", Type, 0, ""},
		{"Sym32", Type, 0, ""},
		{"Sym32.Info", Field, 0, ""},
		{"Sym32.Name", Field, 0, ""},
		{"Sym32.Other", Field, 0, ""},
		{"Sym32.Shndx", Field, 0, ""},
		{"Sym32.Size", Field, 0, ""},
		{"Sym32.Value", Field, 0, ""},
		{"Sym32Size", Const, 0, ""},
		{"Sym64", Type, 0, ""},
		{"Sym64.Info", Field, 0, ""},
		{"Sym64.Name", Field, 0, ""},
		{"Sym64.Other", Field, 0, ""},
		{"Sym64.Shndx", Field, 0, ""},
		{"Sym64.Size", Field, 0, ""},
		{"Sym64.Value", Field, 0, ""},
		{"Sym64Size", Const, 0, ""},
		{"SymBind", Type, 0, ""},
		{"SymType", Type, 0, ""},
		{"SymVis", Type, 0, ""},
		{"Symbol", Type, 0, ""},
		{"Symbol.HasVersion", Field, 24, ""},
		{"Symbol.Info", Field, 0, ""},
		{"Symbol.Library", Field, 13, ""},
		{"Symbol.Name", Field, 0, ""},
		{"Symbol.Other", Field, 0, ""},
		{"Symbol.Section", Field, 0, ""},
		{"Symbol.Size", Field, 0, ""},
		{"Symbol.Value", Field, 0, ""},
		{"Symbol.Version", Field, 13, ""},
		{"Symbol.VersionIndex", Field, 24, ""},
		{"Type", Type, 0, ""},
		{"VER_FLG_BASE", Const, 24, ""},
		{"VER_FLG_INFO", Const, 24, ""},
		{"VER_FLG_WEAK", Const, 24, ""},
		{"Version", Type, 0, ""},
		{"VersionIndex", Type, 24, ""},
	},
	"debug/gosym": {
		{"(*DecodingError).Error", Method, 0, ""},
		{"(*LineTable).LineToPC", Method, 0, ""},
		{"(*LineTable).PCToLine", Method, 0, ""},
		{"(*Sym).BaseName", Method, 0, ""},
		{"(*Sym).PackageName", Method, 0, ""},
		{"(*Sym).ReceiverName", Method, 0, ""},
		{"(*Sym).Static", Method, 0, ""},
		{"(*Table).LineToPC", Method, 0, ""},
		{"(*Table).LookupFunc", Method, 0, ""},
		{"(*Table).LookupSym", Method, 0, ""},
		{"(*Table).PCToFunc", Method, 0, ""},
		{"(*Table).PCToLine", Method, 0, ""},
		{"(*Table).SymByAddr", Method, 0, ""},
		{"(*UnknownLineError).Error", Method, 0, ""},
		{"(Func).BaseName", Method, 0, ""},
		{"(Func).PackageName", Method, 0, ""},
		{"(Func).ReceiverName", Method, 0, ""},
		{"(Func).Static", Method, 0, ""},
		{"(UnknownFileError).Error", Method, 0, ""},
		{"DecodingError", Type, 0, ""},
		{"Func", Type, 0, ""},
		{"Func.End", Field, 0, ""},
		{"Func.Entry", Field, 0, ""},
		{"Func.FrameSize", Field, 0, ""},
		{"Func.LineTable", Field, 0, ""},
		{"Func.Locals", Field, 0, ""},
		{"Func.Obj", Field, 0, ""},
		{"Func.Params", Field, 0, ""},
		{"Func.Sym", Field, 0, ""},
		{"LineTable", Type, 0, ""},
		{"LineTable.Data", Field, 0, ""},
		{"LineTable.Line", Field, 0, ""},
		{"LineTable.PC", Field, 0, ""},
		{"NewLineTable", Func, 0, "func(data []byte, text uint64) *LineTable"},
		{"NewTable", Func, 0, "func(symtab []byte, pcln *LineTable) (*Table, error)"},
		{"Obj", Type, 0, ""},
		{"Obj.Funcs", Field, 0, ""},
		{"Obj.Paths", Field, 0, ""},
		{"Sym", Type, 0, ""},
		{"Sym.Func", Field, 0, ""},
		{"Sym.GoType", Field, 0, ""},
		{"Sym.Name", Field, 0, ""},
		{"Sym.Type", Field, 0, ""},
		{"Sym.Value", Field, 0, ""},
		{"Table", Type, 0, ""},
		{"Table.Files", Field, 0, ""},
		{"Table.Funcs", Field, 0, ""},
		{"Table.Objs", Field, 0, ""},
		{"Table.Syms", Field, 0, ""},
		{"UnknownFileError", Type, 0, ""},
		{"UnknownLineError", Type, 0, ""},
		{"UnknownLineError.File", Field, 0, ""},
		{"UnknownLineError.Line", Field, 0, ""},
	},
	"debug/macho": {
		{"(*FatFile).Close", Method, 3, ""},
		{"(*File).Close", Method, 0, ""},
		{"(*File).DWARF", Method, 0, ""},
		{"(*File).ImportedLibraries", Method, 0, ""},
		{"(*File).ImportedSymbols", Method, 0, ""},
		{"(*File).Section", Method, 0, ""},
		{"(*File).Segment", Method, 0, ""},
		{"(*FormatError).Error", Method, 0, ""},
		{"(*Section).Data", Method, 0, ""},
		{"(*Section).Open", Method, 0, ""},
		{"(*Segment).Data", Method, 0, ""},
		{"(*Segment).Open", Method, 0, ""},
		{"(Cpu).GoString", Method, 0, ""},
		{"(Cpu).String", Method, 0, ""},
		{"(Dylib).Raw", Method, 0, ""},
		{"(Dysymtab).Raw", Method, 0, ""},
		{"(FatArch).Close", Method, 3, ""},
		{"(FatArch).DWARF", Method, 3, ""},
		{"(FatArch).ImportedLibraries", Method, 3, ""},
		{"(FatArch).ImportedSymbols", Method, 3, ""},
		{"(FatArch).Section", Method, 3, ""},
		{"(FatArch).Segment", Method, 3, ""},
		{"(Load).Raw", Method, 0, ""},
		{"(LoadBytes).Raw", Method, 0, ""},
		{"(LoadCmd).GoString", Method, 0, ""},
		{"(LoadCmd).String", Method, 0, ""},
		{"(RelocTypeARM).GoString", Method, 10, ""},
		{"(RelocTypeARM).String", Method, 10, ""},
		{"(RelocTypeARM64).GoString", Method, 10, ""},
		{"(RelocTypeARM64).String", Method, 10, ""},
		{"(RelocTypeGeneric).GoString", Method, 10, ""},
		{"(RelocTypeGeneric).String", Method, 10, ""},
		{"(RelocTypeX86_64).GoString", Method, 10, ""},
		{"(RelocTypeX86_64).String", Method, 10, ""},
		{"(Rpath).Raw", Method, 10, ""},
		{"(Section).ReadAt", Method, 0, ""},
		{"(Segment).Raw", Method, 0, ""},
		{"(Segment).ReadAt", Method, 0, ""},
		{"(Symtab).Raw", Method, 0, ""},
		{"(Type).GoString", Method, 10, ""},
		{"(Type).String", Method, 10, ""},
		{"ARM64_RELOC_ADDEND", Const, 10, ""},
		{"ARM64_RELOC_BRANCH26", Const, 10, ""},
		{"ARM64_RELOC_GOT_LOAD_PAGE21", Const, 10, ""},
		{"ARM64_RELOC_GOT_LOAD_PAGEOFF12", Const, 10, ""},
		{"ARM64_RELOC_PAGE21", Const, 10, ""},
		{"ARM64_RELOC_PAGEOFF12", Const, 10, ""},
		{"ARM64_RELOC_POINTER_TO_GOT", Const, 10, ""},
		{"ARM64_RELOC_SUBTRACTOR", Const, 10, ""},
		{"ARM64_RELOC_TLVP_LOAD_PAGE21", Const, 10, ""},
		{"ARM64_RELOC_TLVP_LOAD_PAGEOFF12", Const, 10, ""},
		{"ARM64_RELOC_UNSIGNED", Const, 10, ""},
		{"ARM_RELOC_BR24", Const, 10, ""},
		{"ARM_RELOC_HALF", Const, 10, ""},
		{"ARM_RELOC_HALF_SECTDIFF", Const, 10, ""},
		{"ARM_RELOC_LOCAL_SECTDIFF", Const, 10, ""},
		{"ARM_RELOC_PAIR", Const, 10, ""},
		{"ARM_RELOC_PB_LA_PTR", Const, 10, ""},
		{"ARM_RELOC_SECTDIFF", Const, 10, ""},
		{"ARM_RELOC_VANILLA", Const, 10, ""},
		{"ARM_THUMB_32BIT_BRANCH", Const, 10, ""},
		{"ARM_THUMB_RELOC_BR22", Const, 10, ""},
		{"Cpu", Type, 0, ""},
		{"Cpu386", Const, 0, ""},
		{"CpuAmd64", Const, 0, ""},
		{"CpuArm", Const, 3, ""},
		{"CpuArm64", Const, 11, ""},
		{"CpuPpc", Const, 3, ""},
		{"CpuPpc64", Const, 3, ""},
		{"Dylib", Type, 0, ""},
		{"Dylib.CompatVersion", Field, 0, ""},
		{"Dylib.CurrentVersion", Field, 0, ""},
		{"Dylib.LoadBytes", Field, 0, ""},
		{"Dylib.Name", Field, 0, ""},
		{"Dylib.Time", Field, 0, ""},
		{"DylibCmd", Type, 0, ""},
		{"DylibCmd.Cmd", Field, 0, ""},
		{"DylibCmd.CompatVersion", Field, 0, ""},
		{"DylibCmd.CurrentVersion", Field, 0, ""},
		{"DylibCmd.Len", Field, 0, ""},
		{"DylibCmd.Name", Field, 0, ""},
		{"DylibCmd.Time", Field, 0, ""},
		{"Dysymtab", Type, 0, ""},
		{"Dysymtab.DysymtabCmd", Field, 0, ""},
		{"Dysymtab.IndirectSyms", Field, 0, ""},
		{"Dysymtab.LoadBytes", Field, 0, ""},
		{"DysymtabCmd", Type, 0, ""},
		{"DysymtabCmd.Cmd", Field, 0, ""},
		{"DysymtabCmd.Extrefsymoff", Field, 0, ""},
		{"DysymtabCmd.Extreloff", Field, 0, ""},
		{"DysymtabCmd.Iextdefsym", Field, 0, ""},
		{"DysymtabCmd.Ilocalsym", Field, 0, ""},
		{"DysymtabCmd.Indirectsymoff", Field, 0, ""},
		{"DysymtabCmd.Iundefsym", Field, 0, ""},
		{"DysymtabCmd.Len", Field, 0, ""},
		{"DysymtabCmd.Locreloff", Field, 0, ""},
		{"DysymtabCmd.Modtaboff", Field, 0, ""},
		{"DysymtabCmd.Nextdefsym", Field, 0, ""},
		{"DysymtabCmd.Nextrefsyms", Field, 0, ""},
		{"DysymtabCmd.Nextrel", Field, 0, ""},
		{"DysymtabCmd.Nindirectsyms", Field, 0, ""},
		{"DysymtabCmd.Nlocalsym", Field, 0, ""},
		{"DysymtabCmd.Nlocrel", Field, 0, ""},
		{"DysymtabCmd.Nmodtab", Field, 0, ""},
		{"DysymtabCmd.Ntoc", Field, 0, ""},
		{"DysymtabCmd.Nundefsym", Field, 0, ""},
		{"DysymtabCmd.Tocoffset", Field, 0, ""},
		{"ErrNotFat", Var, 3, ""},
		{"FatArch", Type, 3, ""},
		{"FatArch.FatArchHeader", Field, 3, ""},
		{"FatArch.File", Field, 3, ""},
		{"FatArchHeader", Type, 3, ""},
		{"FatArchHeader.Align", Field, 3, ""},
		{"FatArchHeader.Cpu", Field, 3, ""},
		{"FatArchHeader.Offset", Field, 3, ""},
		{"FatArchHeader.Size", Field, 3, ""},
		{"FatArchHeader.SubCpu", Field, 3, ""},
		{"FatFile", Type, 3, ""},
		{"FatFile.Arches", Field, 3, ""},
		{"FatFile.Magic", Field, 3, ""},
		{"File", Type, 0, ""},
		{"File.ByteOrder", Field, 0, ""},
		{"File.Dysymtab", Field, 0, ""},
		{"File.FileHeader", Field, 0, ""},
		{"File.Loads", Field, 0, ""},
		{"File.Sections", Field, 0, ""},
		{"File.Symtab", Field, 0, ""},
		{"FileHeader", Type, 0, ""},
		{"FileHeader.Cmdsz", Field, 0, ""},
		{"FileHeader.Cpu", Field, 0, ""},
		{"FileHeader.Flags", Field, 0, ""},
		{"FileHeader.Magic", Field, 0, ""},
		{"FileHeader.Ncmd", Field, 0, ""},
		{"FileHeader.SubCpu", Field, 0, ""},
		{"FileHeader.Type", Field, 0, ""},
		{"FlagAllModsBound", Const, 10, ""},
		{"FlagAllowStackExecution", Const, 10, ""},
		{"FlagAppExtensionSafe", Const, 10, ""},
		{"FlagBindAtLoad", Const, 10, ""},
		{"FlagBindsToWeak", Const, 10, ""},
		{"FlagCanonical", Const, 10, ""},
		{"FlagDeadStrippableDylib", Const, 10, ""},
		{"FlagDyldLink", Const, 10, ""},
		{"FlagForceFlat", Const, 10, ""},
		{"FlagHasTLVDescriptors", Const, 10, ""},
		{"FlagIncrLink", Const, 10, ""},
		{"FlagLazyInit", Const, 10, ""},
		{"FlagNoFixPrebinding", Const, 10, ""},
		{"FlagNoHeapExecution", Const, 10, ""},
		{"FlagNoMultiDefs", Const, 10, ""},
		{"FlagNoReexportedDylibs", Const, 10, ""},
		{"FlagNoUndefs", Const, 10, ""},
		{"FlagPIE", Const, 10, ""},
		{"FlagPrebindable", Const, 10, ""},
		{"FlagPrebound", Const, 10, ""},
		{"FlagRootSafe", Const, 10, ""},
		{"FlagSetuidSafe", Const, 10, ""},
		{"FlagSplitSegs", Const, 10, ""},
		{"FlagSubsectionsViaSymbols", Const, 10, ""},
		{"FlagTwoLevel", Const, 10, ""},
		{"FlagWeakDefines", Const, 10, ""},
		{"FormatError", Type, 0, ""},
		{"GENERIC_RELOC_LOCAL_SECTDIFF", Const, 10, ""},
		{"GENERIC_RELOC_PAIR", Const, 10, ""},
		{"GENERIC_RELOC_PB_LA_PTR", Const, 10, ""},
		{"GENERIC_RELOC_SECTDIFF", Const, 10, ""},
		{"GENERIC_RELOC_TLV", Const, 10, ""},
		{"GENERIC_RELOC_VANILLA", Const, 10, ""},
		{"Load", Type, 0, ""},
		{"LoadBytes", Type, 0, ""},
		{"LoadCmd", Type, 0, ""},
		{"LoadCmdDylib", Const, 0, ""},
		{"LoadCmdDylinker", Const, 0, ""},
		{"LoadCmdDysymtab", Const, 0, ""},
		{"LoadCmdRpath", Const, 10, ""},
		{"LoadCmdSegment", Const, 0, ""},
		{"LoadCmdSegment64", Const, 0, ""},
		{"LoadCmdSymtab", Const, 0, ""},
		{"LoadCmdThread", Const, 0, ""},
		{"LoadCmdUnixThread", Const, 0, ""},
		{"Magic32", Const, 0, ""},
		{"Magic64", Const, 0, ""},
		{"MagicFat", Const, 3, ""},
		{"NewFatFile", Func, 3, "func(r io.ReaderAt) (*FatFile, error)"},
		{"NewFile", Func, 0, "func(r io.ReaderAt) (*File, error)"},
		{"Nlist32", Type, 0, ""},
		{"Nlist32.Desc", Field, 0, ""},
		{"Nlist32.Name", Field, 0, ""},
		{"Nlist32.Sect", Field, 0, ""},
		{"Nlist32.Type", Field, 0, ""},
		{"Nlist32.Value", Field, 0, ""},
		{"Nlist64", Type, 0, ""},
		{"Nlist64.Desc", Field, 0, ""},
		{"Nlist64.Name", Field, 0, ""},
		{"Nlist64.Sect", Field, 0, ""},
		{"Nlist64.Type", Field, 0, ""},
		{"Nlist64.Value", Field, 0, ""},
		{"Open", Func, 0, "func(name string) (*File, error)"},
		{"OpenFat", Func, 3, "func(name string) (*FatFile, error)"},
		{"Regs386", Type, 0, ""},
		{"Regs386.AX", Field, 0, ""},
		{"Regs386.BP", Field, 0, ""},
		{"Regs386.BX", Field, 0, ""},
		{"Regs386.CS", Field, 0, ""},
		{"Regs386.CX", Field, 0, ""},
		{"Regs386.DI", Field, 0, ""},
		{"Regs386.DS", Field, 0, ""},
		{"Regs386.DX", Field, 0, ""},
		{"Regs386.ES", Field, 0, ""},
		{"Regs386.FLAGS", Field, 0, ""},
		{"Regs386.FS", Field, 0, ""},
		{"Regs386.GS", Field, 0, ""},
		{"Regs386.IP", Field, 0, ""},
		{"Regs386.SI", Field, 0, ""},
		{"Regs386.SP", Field, 0, ""},
		{"Regs386.SS", Field, 0, ""},
		{"RegsAMD64", Type, 0, ""},
		{"RegsAMD64.AX", Field, 0, ""},
		{"RegsAMD64.BP", Field, 0, ""},
		{"RegsAMD64.BX", Field, 0, ""},
		{"RegsAMD64.CS", Field, 0, ""},
		{"RegsAMD64.CX", Field, 0, ""},
		{"RegsAMD64.DI", Field, 0, ""},
		{"RegsAMD64.DX", Field, 0, ""},
		{"RegsAMD64.FLAGS", Field, 0, ""},
		{"RegsAMD64.FS", Field, 0, ""},
		{"RegsAMD64.GS", Field, 0, ""},
		{"RegsAMD64.IP", Field, 0, ""},
		{"RegsAMD64.R10", Field, 0, ""},
		{"RegsAMD64.R11", Field, 0, ""},
		{"RegsAMD64.R12", Field, 0, ""},
		{"RegsAMD64.R13", Field, 0, ""},
		{"RegsAMD64.R14", Field, 0, ""},
		{"RegsAMD64.R15", Field, 0, ""},
		{"RegsAMD64.R8", Field, 0, ""},
		{"RegsAMD64.R9", Field, 0, ""},
		{"RegsAMD64.SI", Field, 0, ""},
		{"RegsAMD64.SP", Field, 0, ""},
		{"Reloc", Type, 10, ""},
		{"Reloc.Addr", Field, 10, ""},
		{"Reloc.Extern", Field, 10, ""},
		{"Reloc.Len", Field, 10, ""},
		{"Reloc.Pcrel", Field, 10, ""},
		{"Reloc.Scattered", Field, 10, ""},
		{"Reloc.Type", Field, 10, ""},
		{"Reloc.Value", Field, 10, ""},
		{"RelocTypeARM", Type, 10, ""},
		{"RelocTypeARM64", Type, 10, ""},
		{"RelocTypeGeneric", Type, 10, ""},
		{"RelocTypeX86_64", Type, 10, ""},
		{"Rpath", Type, 10, ""},
		{"Rpath.LoadBytes", Field, 10, ""},
		{"Rpath.Path", Field, 10, ""},
		{"RpathCmd", Type, 10, ""},
		{"RpathCmd.Cmd", Field, 10, ""},
		{"RpathCmd.Len", Field, 10, ""},
		{"RpathCmd.Path", Field, 10, ""},
		{"Section", Type, 0, ""},
		{"Section.ReaderAt", Field, 0, ""},
		{"Section.Relocs", Field, 10, ""},
		{"Section.SectionHeader", Field, 0, ""},
		{"Section32", Type, 0, ""},
		{"Section32.Addr", Field, 0, ""},
		{"Section32.Align", Field, 0, ""},
		{"Section32.Flags", Field, 0, ""},
		{"Section32.Name", Field, 0, ""},
		{"Section32.Nreloc", Field, 0, ""},
		{"Section32.Offset", Field, 0, ""},
		{"Section32.Reloff", Field, 0, ""},
		{"Section32.Reserve1", Field, 0, ""},
		{"Section32.Reserve2", Field, 0, ""},
		{"Section32.Seg", Field, 0, ""},
		{"Section32.Size", Field, 0, ""},
		{"Section64", Type, 0, ""},
		{"Section64.Addr", Field, 0, ""},
		{"Section64.Align", Field, 0, ""},
		{"Section64.Flags", Field, 0, ""},
		{"Section64.Name", Field, 0, ""},
		{"Section64.Nreloc", Field, 0, ""},
		{"Section64.Offset", Field, 0, ""},
		{"Section64.Reloff", Field, 0, ""},
		{"Section64.Reserve1", Field, 0, ""},
		{"Section64.Reserve2", Field, 0, ""},
		{"Section64.Reserve3", Field, 0, ""},
		{"Section64.Seg", Field, 0, ""},
		{"Section64.Size", Field, 0, ""},
		{"SectionHeader", Type, 0, ""},
		{"SectionHeader.Addr", Field, 0, ""},
		{"SectionHeader.Align", Field, 0, ""},
		{"SectionHeader.Flags", Field, 0, ""},
		{"SectionHeader.Name", Field, 0, ""},
		{"SectionHeader.Nreloc", Field, 0, ""},
		{"SectionHeader.Offset", Field, 0, ""},
		{"SectionHeader.Reloff", Field, 0, ""},
		{"SectionHeader.Seg", Field, 0, ""},
		{"SectionHeader.Size", Field, 0, ""},
		{"Segment", Type, 0, ""},
		{"Segment.LoadBytes", Field, 0, ""},
		{"Segment.ReaderAt", Field, 0, ""},
		{"Segment.SegmentHeader", Field, 0, ""},
		{"Segment32", Type, 0, ""},
		{"Segment32.Addr", Field, 0, ""},
		{"Segment32.Cmd", Field, 0, ""},
		{"Segment32.Filesz", Field, 0, ""},
		{"Segment32.Flag", Field, 0, ""},
		{"Segment32.Len", Field, 0, ""},
		{"Segment32.Maxprot", Field, 0, ""},
		{"Segment32.Memsz", Field, 0, ""},
		{"Segment32.Name", Field, 0, ""},
		{"Segment32.Nsect", Field, 0, ""},
		{"Segment32.Offset", Field, 0, ""},
		{"Segment32.Prot", Field, 0, ""},
		{"Segment64", Type, 0, ""},
		{"Segment64.Addr", Field, 0, ""},
		{"Segment64.Cmd", Field, 0, ""},
		{"Segment64.Filesz", Field, 0, ""},
		{"Segment64.Flag", Field, 0, ""},
		{"Segment64.Len", Field, 0, ""},
		{"Segment64.Maxprot", Field, 0, ""},
		{"Segment64.Memsz", Field, 0, ""},
		{"Segment64.Name", Field, 0, ""},
		{"Segment64.Nsect", Field, 0, ""},
		{"Segment64.Offset", Field, 0, ""},
		{"Segment64.Prot", Field, 0, ""},
		{"SegmentHeader", Type, 0, ""},
		{"SegmentHeader.Addr", Field, 0, ""},
		{"SegmentHeader.Cmd", Field, 0, ""},
		{"SegmentHeader.Filesz", Field, 0, ""},
		{"SegmentHeader.Flag", Field, 0, ""},
		{"SegmentHeader.Len", Field, 0, ""},
		{"SegmentHeader.Maxprot", Field, 0, ""},
		{"SegmentHeader.Memsz", Field, 0, ""},
		{"SegmentHeader.Name", Field, 0, ""},
		{"SegmentHeader.Nsect", Field, 0, ""},
		{"SegmentHeader.Offset", Field, 0, ""},
		{"SegmentHeader.Prot", Field, 0, ""},
		{"Symbol", Type, 0, ""},
		{"Symbol.Desc", Field, 0, ""},
		{"Symbol.Name", Field, 0, ""},
		{"Symbol.Sect", Field, 0, ""},
		{"Symbol.Type", Field, 0, ""},
		{"Symbol.Value", Field, 0, ""},
		{"Symtab", Type, 0, ""},
		{"Symtab.LoadBytes", Field, 0, ""},
		{"Symtab.Syms", Field, 0, ""},
		{"Symtab.SymtabCmd", Field, 0, ""},
		{"SymtabCmd", Type, 0, ""},
		{"SymtabCmd.Cmd", Field, 0, ""},
		{"SymtabCmd.Len", Field, 0, ""},
		{"SymtabCmd.Nsyms", Field, 0, ""},
		{"SymtabCmd.Stroff", Field, 0, ""},
		{"SymtabCmd.Strsize", Field, 0, ""},
		{"SymtabCmd.Symoff", Field, 0, ""},
		{"Thread", Type, 0, ""},
		{"Thread.Cmd", Field, 0, ""},
		{"Thread.Data", Field, 0, ""},
		{"Thread.Len", Field, 0, ""},
		{"Thread.Type", Field, 0, ""},
		{"Type", Type, 0, ""},
		{"TypeBundle", Const, 3, ""},
		{"TypeDylib", Const, 3, ""},
		{"TypeExec", Const, 0, ""},
		{"TypeObj", Const, 0, ""},
		{"X86_64_RELOC_BRANCH", Const, 10, ""},
		{"X86_64_RELOC_GOT", Const, 10, ""},
		{"X86_64_RELOC_GOT_LOAD", Const, 10, ""},
		{"X86_64_RELOC_SIGNED", Const, 10, ""},
		{"X86_64_RELOC_SIGNED_1", Const, 10, ""},
		{"X86_64_RELOC_SIGNED_2", Const, 10, ""},
		{"X86_64_RELOC_SIGNED_4", Const, 10, ""},
		{"X86_64_RELOC_SUBTRACTOR", Const, 10, ""},
		{"X86_64_RELOC_TLV", Const, 10, ""},
		{"X86_64_RELOC_UNSIGNED", Const, 10, ""},
	},
	"debug/pe": {
		{"(*COFFSymbol).FullName", Method, 8, ""},
		{"(*File).COFFSymbolReadSectionDefAux", Method, 19, ""},
		{"(*File).Close", Method, 0, ""},
		{"(*File).DWARF", Method, 0, ""},
		{"(*File).ImportedLibraries", Method, 0, ""},
		{"(*File).ImportedSymbols", Method, 0, ""},
		{"(*File).Section", Method, 0, ""},
		{"(*FormatError).Error", Method, 0, ""},
		{"(*Section).Data", Method, 0, ""},
		{"(*Section).Open", Method, 0, ""},
		{"(Section).ReadAt", Method, 0, ""},
		{"(StringTable).String", Method, 8, ""},
		{"COFFSymbol", Type, 1, ""},
		{"COFFSymbol.Name", Field, 1, ""},
		{"COFFSymbol.NumberOfAuxSymbols", Field, 1, ""},
		{"COFFSymbol.SectionNumber", Field, 1, ""},
		{"COFFSymbol.StorageClass", Field, 1, ""},
		{"COFFSymbol.Type", Field, 1, ""},
		{"COFFSymbol.Value", Field, 1, ""},
		{"COFFSymbolAuxFormat5", Type, 19, ""},
		{"COFFSymbolAuxFormat5.Checksum", Field, 19, ""},
		{"COFFSymbolAuxFormat5.NumLineNumbers", Field, 19, ""},
		{"COFFSymbolAuxFormat5.NumRelocs", Field, 19, ""},
		{"COFFSymbolAuxFormat5.SecNum", Field, 19, ""},
		{"COFFSymbolAuxFormat5.Selection", Field, 19, ""},
		{"COFFSymbolAuxFormat5.Size", Field, 19, ""},
		{"COFFSymbolSize", Const, 1, ""},
		{"DataDirectory", Type, 3, ""},
		{"DataDirectory.Size", Field, 3, ""},
		{"DataDirectory.VirtualAddress", Field, 3, ""},
		{"File", Type, 0, ""},
		{"File.COFFSymbols", Field, 8, ""},
		{"File.FileHeader", Field, 0, ""},
		{"File.OptionalHeader", Field, 3, ""},
		{"File.Sections", Field, 0, ""},
		{"File.StringTable", Field, 8, ""},
		{"File.Symbols", Field, 1, ""},
		{"FileHeader", Type, 0, ""},
		{"FileHeader.Characteristics", Field, 0, ""},
		{"FileHeader.Machine", Field, 0, ""},
		{"FileHeader.NumberOfSections", Field, 0, ""},
		{"FileHeader.NumberOfSymbols", Field, 0, ""},
		{"FileHeader.PointerToSymbolTable", Field, 0, ""},
		{"FileHeader.SizeOfOptionalHeader", Field, 0, ""},
		{"FileHeader.TimeDateStamp", Field, 0, ""},
		{"FormatError", Type, 0, ""},
		{"IMAGE_COMDAT_SELECT_ANY", Const, 19, ""},
		{"IMAGE_COMDAT_SELECT_ASSOCIATIVE", Const, 19, ""},
		{"IMAGE_COMDAT_SELECT_EXACT_MATCH", Const, 19, ""},
		{"IMAGE_COMDAT_SELECT_LARGEST", Const, 19, ""},
		{"IMAGE_COMDAT_SELECT_NODUPLICATES", Const, 19, ""},
		{"IMAGE_COMDAT_SELECT_SAME_SIZE", Const, 19, ""},
		{"IMAGE_DIRECTORY_ENTRY_ARCHITECTURE", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_BASERELOC", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_BOUND_IMPORT", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_COM_DESCRIPTOR", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_DEBUG", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_DELAY_IMPORT", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_EXCEPTION", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_EXPORT", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_GLOBALPTR", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_IAT", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_IMPORT", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_LOAD_CONFIG", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_RESOURCE", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_SECURITY", Const, 11, ""},
		{"IMAGE_DIRECTORY_ENTRY_TLS", Const, 11, ""},
		{"IMAGE_DLLCHARACTERISTICS_APPCONTAINER", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_DYNAMIC_BASE", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_FORCE_INTEGRITY", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_GUARD_CF", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_HIGH_ENTROPY_VA", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_NO_BIND", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_NO_ISOLATION", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_NO_SEH", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_NX_COMPAT", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_TERMINAL_SERVER_AWARE", Const, 15, ""},
		{"IMAGE_DLLCHARACTERISTICS_WDM_DRIVER", Const, 15, ""},
		{"IMAGE_FILE_32BIT_MACHINE", Const, 15, ""},
		{"IMAGE_FILE_AGGRESIVE_WS_TRIM", Const, 15, ""},
		{"IMAGE_FILE_BYTES_REVERSED_HI", Const, 15, ""},
		{"IMAGE_FILE_BYTES_REVERSED_LO", Const, 15, ""},
		{"IMAGE_FILE_DEBUG_STRIPPED", Const, 15, ""},
		{"IMAGE_FILE_DLL", Const, 15, ""},
		{"IMAGE_FILE_EXECUTABLE_IMAGE", Const, 15, ""},
		{"IMAGE_FILE_LARGE_ADDRESS_AWARE", Const, 15, ""},
		{"IMAGE_FILE_LINE_NUMS_STRIPPED", Const, 15, ""},
		{"IMAGE_FILE_LOCAL_SYMS_STRIPPED", Const, 15, ""},
		{"IMAGE_FILE_MACHINE_AM33", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_AMD64", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_ARM", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_ARM64", Const, 11, ""},
		{"IMAGE_FILE_MACHINE_ARMNT", Const, 12, ""},
		{"IMAGE_FILE_MACHINE_EBC", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_I386", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_IA64", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_LOONGARCH32", Const, 19, ""},
		{"IMAGE_FILE_MACHINE_LOONGARCH64", Const, 19, ""},
		{"IMAGE_FILE_MACHINE_M32R", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_MIPS16", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_MIPSFPU", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_MIPSFPU16", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_POWERPC", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_POWERPCFP", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_R4000", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_RISCV128", Const, 20, ""},
		{"IMAGE_FILE_MACHINE_RISCV32", Const, 20, ""},
		{"IMAGE_FILE_MACHINE_RISCV64", Const, 20, ""},
		{"IMAGE_FILE_MACHINE_SH3", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_SH3DSP", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_SH4", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_SH5", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_THUMB", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_UNKNOWN", Const, 0, ""},
		{"IMAGE_FILE_MACHINE_WCEMIPSV2", Const, 0, ""},
		{"IMAGE_FILE_NET_RUN_FROM_SWAP", Const, 15, ""},
		{"IMAGE_FILE_RELOCS_STRIPPED", Const, 15, ""},
		{"IMAGE_FILE_REMOVABLE_RUN_FROM_SWAP", Const, 15, ""},
		{"IMAGE_FILE_SYSTEM", Const, 15, ""},
		{"IMAGE_FILE_UP_SYSTEM_ONLY", Const, 15, ""},
		{"IMAGE_SCN_CNT_CODE", Const, 19, ""},
		{"IMAGE_SCN_CNT_INITIALIZED_DATA", Const, 19, ""},
		{"IMAGE_SCN_CNT_UNINITIALIZED_DATA", Const, 19, ""},
		{"IMAGE_SCN_LNK_COMDAT", Const, 19, ""},
		{"IMAGE_SCN_MEM_DISCARDABLE", Const, 19, ""},
		{"IMAGE_SCN_MEM_EXECUTE", Const, 19, ""},
		{"IMAGE_SCN_MEM_READ", Const, 19, ""},
		{"IMAGE_SCN_MEM_WRITE", Const, 19, ""},
		{"IMAGE_SUBSYSTEM_EFI_APPLICATION", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_EFI_BOOT_SERVICE_DRIVER", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_EFI_ROM", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_EFI_RUNTIME_DRIVER", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_NATIVE", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_NATIVE_WINDOWS", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_OS2_CUI", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_POSIX_CUI", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_UNKNOWN", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_WINDOWS_BOOT_APPLICATION", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_WINDOWS_CE_GUI", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_WINDOWS_CUI", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_WINDOWS_GUI", Const, 15, ""},
		{"IMAGE_SUBSYSTEM_XBOX", Const, 15, ""},
		{"ImportDirectory", Type, 0, ""},
		{"ImportDirectory.FirstThunk", Field, 0, ""},
		{"ImportDirectory.ForwarderChain", Field, 0, ""},
		{"ImportDirectory.Name", Field, 0, ""},
		{"ImportDirectory.OriginalFirstThunk", Field, 0, ""},
		{"ImportDirectory.TimeDateStamp", Field, 0, ""},
		{"NewFile", Func, 0, "func(r io.ReaderAt) (*File, error)"},
		{"Open", Func, 0, "func(name string) (*File, error)"},
		{"OptionalHeader32", Type, 3, ""},
		{"OptionalHeader32.AddressOfEntryPoint", Field, 3, ""},
		{"OptionalHeader32.BaseOfCode", Field, 3, ""},
		{"OptionalHeader32.BaseOfData", Field, 3, ""},
		{"OptionalHeader32.CheckSum", Field, 3, ""},
		{"OptionalHeader32.DataDirectory", Field, 3, ""},
		{"OptionalHeader32.DllCharacteristics", Field, 3, ""},
		{"OptionalHeader32.FileAlignment", Field, 3, ""},
		{"OptionalHeader32.ImageBase", Field, 3, ""},
		{"OptionalHeader32.LoaderFlags", Field, 3, ""},
		{"OptionalHeader32.Magic", Field, 3, ""},
		{"OptionalHeader32.MajorImageVersion", Field, 3, ""},
		{"OptionalHeader32.MajorLinkerVersion", Field, 3, ""},
		{"OptionalHeader32.MajorOperatingSystemVersion", Field, 3, ""},
		{"OptionalHeader32.MajorSubsystemVersion", Field, 3, ""},
		{"OptionalHeader32.MinorImageVersion", Field, 3, ""},
		{"OptionalHeader32.MinorLinkerVersion", Field, 3, ""},
		{"OptionalHeader32.MinorOperatingSystemVersion", Field, 3, ""},
		{"OptionalHeader32.MinorSubsystemVersion", Field, 3, ""},
		{"OptionalHeader32.NumberOfRvaAndSizes", Field, 3, ""},
		{"OptionalHeader32.SectionAlignment", Field, 3, ""},
		{"OptionalHeader32.SizeOfCode", Field, 3, ""},
		{"OptionalHeader32.SizeOfHeaders", Field, 3, ""},
		{"OptionalHeader32.SizeOfHeapCommit", Field, 3, ""},
		{"OptionalHeader32.SizeOfHeapReserve", Field, 3, ""},
		{"OptionalHeader32.SizeOfImage", Field, 3, ""},
		{"OptionalHeader32.SizeOfInitializedData", Field, 3, ""},
		{"OptionalHeader32.SizeOfStackCommit", Field, 3, ""},
		{"OptionalHeader32.SizeOfStackReserve", Field, 3, ""},
		{"OptionalHeader32.SizeOfUninitializedData", Field, 3, ""},
		{"OptionalHeader32.Subsystem", Field, 3, ""},
		{"OptionalHeader32.Win32VersionValue", Field, 3, ""},
		{"OptionalHeader64", Type, 3, ""},
		{"OptionalHeader64.AddressOfEntryPoint", Field, 3, ""},
		{"OptionalHeader64.BaseOfCode", Field, 3, ""},
		{"OptionalHeader64.CheckSum", Field, 3, ""},
		{"OptionalHeader64.DataDirectory", Field, 3, ""},
		{"OptionalHeader64.DllCharacteristics", Field, 3, ""},
		{"OptionalHeader64.FileAlignment", Field, 3, ""},
		{"OptionalHeader64.ImageBase", Field, 3, ""},
		{"OptionalHeader64.LoaderFlags", Field, 3, ""},
		{"OptionalHeader64.Magic", Field, 3, ""},
		{"OptionalHeader64.MajorImageVersion", Field, 3, ""},
		{"OptionalHeader64.MajorLinkerVersion", Field, 3, ""},
		{"OptionalHeader64.MajorOperatingSystemVersion", Field, 3, ""},
		{"OptionalHeader64.MajorSubsystemVersion", Field, 3, ""},
		{"OptionalHeader64.MinorImageVersion", Field, 3, ""},
		{"OptionalHeader64.MinorLinkerVersion", Field, 3, ""},
		{"OptionalHeader64.MinorOperatingSystemVersion", Field, 3, ""},
		{"OptionalHeader64.MinorSubsystemVersion", Field, 3, ""},
		{"OptionalHeader64.NumberOfRvaAndSizes", Field, 3, ""},
		{"OptionalHeader64.SectionAlignment", Field, 3, ""},
		{"OptionalHeader64.SizeOfCode", Field, 3, ""},
		{"OptionalHeader64.SizeOfHeaders", Field, 3, ""},
		{"OptionalHeader64.SizeOfHeapCommit", Field, 3, ""},
		{"OptionalHeader64.SizeOfHeapReserve", Field, 3, ""},
		{"OptionalHeader64.SizeOfImage", Field, 3, ""},
		{"OptionalHeader64.SizeOfInitializedData", Field, 3, ""},
		{"OptionalHeader64.SizeOfStackCommit", Field, 3, ""},
		{"OptionalHeader64.SizeOfStackReserve", Field, 3, ""},
		{"OptionalHeader64.SizeOfUninitializedData", Field, 3, ""},
		{"OptionalHeader64.Subsystem", Field, 3, ""},
		{"OptionalHeader64.Win32VersionValue", Field, 3, ""},
		{"Reloc", Type, 8, ""},
		{"Reloc.SymbolTableIndex", Field, 8, ""},
		{"Reloc.Type", Field, 8, ""},
		{"Reloc.VirtualAddress", Field, 8, ""},
		{"Section", Type, 0, ""},
		{"Section.ReaderAt", Field, 0, ""},
		{"Section.Relocs", Field, 8, ""},
		{"Section.SectionHeader", Field, 0, ""},
		{"SectionHeader", Type, 0, ""},
		{"SectionHeader.Characteristics", Field, 0, ""},
		{"SectionHeader.Name", Field, 0, ""},
		{"SectionHeader.NumberOfLineNumbers", Field, 0, ""},
		{"SectionHeader.NumberOfRelocations", Field, 0, ""},
		{"SectionHeader.Offset", Field, 0, ""},
		{"SectionHeader.PointerToLineNumbers", Field, 0, ""},
		{"SectionHeader.PointerToRelocations", Field, 0, ""},
		{"SectionHeader.Size", Field, 0, ""},
		{"SectionHeader.VirtualAddress", Field, 0, ""},
		{"SectionHeader.VirtualSize", Field, 0, ""},
		{"SectionHeader32", Type, 0, ""},
		{"SectionHeader32.Characteristics", Field, 0, ""},
		{"SectionHeader32.Name", Field, 0, ""},
		{"SectionHeader32.NumberOfLineNumbers", Field, 0, ""},
		{"SectionHeader32.NumberOfRelocations", Field, 0, ""},
		{"SectionHeader32.PointerToLineNumbers", Field, 0, ""},
		{"SectionHeader32.PointerToRawData", Field, 0, ""},
		{"SectionHeader32.PointerToRelocations", Field, 0, ""},
		{"SectionHeader32.SizeOfRawData", Field, 0, ""},
		{"SectionHeader32.VirtualAddress", Field, 0, ""},
		{"SectionHeader32.VirtualSize", Field, 0, ""},
		{"StringTable", Type, 8, ""},
		{"Symbol", Type, 1, ""},
		{"Symbol.Name", Field, 1, ""},
		{"Symbol.SectionNumber", Field, 1, ""},
		{"Symbol.StorageClass", Field, 1, ""},
		{"Symbol.Type", Field, 1, ""},
		{"Symbol.Value", Field, 1, ""},
	},
	"debug/plan9obj": {
		{"(*File).Close", Method, 3, ""},
		{"(*File).Section", Method, 3, ""},
		{"(*File).Symbols", Method, 3, ""},
		{"(*Section).Data", Method, 3, ""},
		{"(*Section).Open", Method, 3, ""},
		{"(Section).ReadAt", Method, 3, ""},
		{"ErrNoSymbols", Var, 18, ""},
		{"File", Type, 3, ""},
		{"File.FileHeader", Field, 3, ""},
		{"File.Sections", Field, 3, ""},
		{"FileHeader", Type, 3, ""},
		{"FileHeader.Bss", Field, 3, ""},
		{"FileHeader.Entry", Field, 3, ""},
		{"FileHeader.HdrSize", Field, 4, ""},
		{"FileHeader.LoadAddress", Field, 4, ""},
		{"FileHeader.Magic", Field, 3, ""},
		{"FileHeader.PtrSize", Field, 3, ""},
		{"Magic386", Const, 3, ""},
		{"Magic64", Const, 3, ""},
		{"MagicAMD64", Const, 3, ""},
		{"MagicARM", Const, 3, ""},
		{"NewFile", Func, 3, "func(r io.ReaderAt) (*File, error)"},
		{"Open", Func, 3, "func(name string) (*File, error)"},
		{"Section", Type, 3, ""},
		{"Section.ReaderAt", Field, 3, ""},
		{"Section.SectionHeader", Field, 3, ""},
		{"SectionHeader", Type, 3, ""},
		{"SectionHeader.Name", Field, 3, ""},
		{"SectionHeader.Offset", Field, 3, ""},
		{"SectionHeader.Size", Field, 3, ""},
		{"Sym", Type, 3, ""},
		{"Sym.Name", Field, 3, ""},
		{"Sym.Type", Field, 3, ""},
		{"Sym.Value", Field, 3, ""},
	},
	"embed": {
		{"(FS).Open", Method, 16, ""},
		{"(FS).ReadDir", Method, 16, ""},
		{"(FS).ReadFile", Method, 16, ""},
		{"FS", Type, 16, ""},
	},
	"encoding": {
		{"(BinaryAppender).AppendBinary", Method, 24, ""},
		{"(BinaryMarshaler).MarshalBinary", Method, 2, ""},
		{"(BinaryUnmarshaler).UnmarshalBinary", Method, 2, ""},
		{"(TextAppender).AppendText", Method, 24, ""},
		{"(TextMarshaler).MarshalText", Method, 2, ""},
		{"(TextUnmarshaler).UnmarshalText", Method, 2, ""},
		{"BinaryAppender", Type, 24, ""},
		{"BinaryMarshaler", Type, 2, ""},
		{"BinaryUnmarshaler", Type, 2, ""},
		{"TextAppender", Type, 24, ""},
		{"TextMarshaler", Type, 2, ""},
		{"TextUnmarshaler", Type, 2, ""},
	},
	"encoding/ascii85": {
		{"(CorruptInputError).Error", Method, 0, ""},
		{"CorruptInputError", Type, 0, ""},
		{"Decode", Func, 0, "func(dst []byte, src []byte, flush bool) (ndst int, nsrc int, err error)"},
		{"Encode", Func, 0, "func(dst []byte, src []byte) int"},
		{"MaxEncodedLen", Func, 0, "func(n int) int"},
		{"NewDecoder", Func, 0, "func(r io.Reader) io.Reader"},
		{"NewEncoder", Func, 0, "func(w io.Writer) io.WriteCloser"},
	},
	"encoding/asn1": {
		{"(BitString).At", Method, 0, ""},
		{"(BitString).RightAlign", Method, 0, ""},
		{"(ObjectIdentifier).Equal", Method, 0, ""},
		{"(ObjectIdentifier).String", Method, 3, ""},
		{"(StructuralError).Error", Method, 0, ""},
		{"(SyntaxError).Error", Method, 0, ""},
		{"BitString", Type, 0, ""},
		{"BitString.BitLength", Field, 0, ""},
		{"BitString.Bytes", Field, 0, ""},
		{"ClassApplication", Const, 6, ""},
		{"ClassContextSpecific", Const, 6, ""},
		{"ClassPrivate", Const, 6, ""},
		{"ClassUniversal", Const, 6, ""},
		{"Enumerated", Type, 0, ""},
		{"Flag", Type, 0, ""},
		{"Marshal", Func, 0, "func(val any) ([]byte, error)"},
		{"MarshalWithParams", Func, 10, "func(val any, params string) ([]byte, error)"},
		{"NullBytes", Var, 9, ""},
		{"NullRawValue", Var, 9, ""},
		{"ObjectIdentifier", Type, 0, ""},
		{"RawContent", Type, 0, ""},
		{"RawValue", Type, 0, ""},
		{"RawValue.Bytes", Field, 0, ""},
		{"RawValue.Class", Field, 0, ""},
		{"RawValue.FullBytes", Field, 0, ""},
		{"RawValue.IsCompound", Field, 0, ""},
		{"RawValue.Tag", Field, 0, ""},
		{"StructuralError", Type, 0, ""},
		{"StructuralError.Msg", Field, 0, ""},
		{"SyntaxError", Type, 0, ""},
		{"SyntaxError.Msg", Field, 0, ""},
		{"TagBMPString", Const, 14, ""},
		{"TagBitString", Const, 6, ""},
		{"TagBoolean", Const, 6, ""},
		{"TagEnum", Const, 6, ""},
		{"TagGeneralString", Const, 6, ""},
		{"TagGeneralizedTime", Const, 6, ""},
		{"TagIA5String", Const, 6, ""},
		{"TagInteger", Const, 6, ""},
		{"TagNull", Const, 9, ""},
		{"TagNumericString", Const, 10, ""},
		{"TagOID", Const, 6, ""},
		{"TagOctetString", Const, 6, ""},
		{"TagPrintableString", Const, 6, ""},
		{"TagSequence", Const, 6, ""},
		{"TagSet", Const, 6, ""},
		{"TagT61String", Const, 6, ""},
		{"TagUTCTime", Const, 6, ""},
		{"TagUTF8String", Const, 6, ""},
		{"Unmarshal", Func, 0, "func(b []byte, val any) (rest []byte, err error)"},
		{"UnmarshalWithParams", Func, 0, "func(b []byte, val any, params string) (rest []byte, err error)"},
	},
	"encoding/base32": {
		{"(*Encoding).AppendDecode", Method, 22, ""},
		{"(*Encoding).AppendEncode", Method, 22, ""},
		{"(*Encoding).Decode", Method, 0, ""},
		{"(*Encoding).DecodeString", Method, 0, ""},
		{"(*Encoding).DecodedLen", Method, 0, ""},
		{"(*Encoding).Encode", Method, 0, ""},
		{"(*Encoding).EncodeToString", Method, 0, ""},
		{"(*Encoding).EncodedLen", Method, 0, ""},
		{"(CorruptInputError).Error", Method, 0, ""},
		{"(Encoding).WithPadding", Method, 9, ""},
		{"CorruptInputError", Type, 0, ""},
		{"Encoding", Type, 0, ""},
		{"HexEncoding", Var, 0, ""},
		{"NewDecoder", Func, 0, "func(enc *Encoding, r io.Reader) io.Reader"},
		{"NewEncoder", Func, 0, "func(enc *Encoding, w io.Writer) io.WriteCloser"},
		{"NewEncoding", Func, 0, "func(encoder string) *Encoding"},
		{"NoPadding", Const, 9, ""},
		{"StdEncoding", Var, 0, ""},
		{"StdPadding", Const, 9, ""},
	},
	"encoding/base64": {
		{"(*Encoding).AppendDecode", Method, 22, ""},
		{"(*Encoding).AppendEncode", Method, 22, ""},
		{"(*Encoding).Decode", Method, 0, ""},
		{"(*Encoding).DecodeString", Method, 0, ""},
		{"(*Encoding).DecodedLen", Method, 0, ""},
		{"(*Encoding).Encode", Method, 0, ""},
		{"(*Encoding).EncodeToString", Method, 0, ""},
		{"(*Encoding).EncodedLen", Method, 0, ""},
		{"(CorruptInputError).Error", Method, 0, ""},
		{"(Encoding).Strict", Method, 8, ""},
		{"(Encoding).WithPadding", Method, 5, ""},
		{"CorruptInputError", Type, 0, ""},
		{"Encoding", Type, 0, ""},
		{"NewDecoder", Func, 0, "func(enc *Encoding, r io.Reader) io.Reader"},
		{"NewEncoder", Func, 0, "func(enc *Encoding, w io.Writer) io.WriteCloser"},
		{"NewEncoding", Func, 0, "func(encoder string) *Encoding"},
		{"NoPadding", Const, 5, ""},
		{"RawStdEncoding", Var, 5, ""},
		{"RawURLEncoding", Var, 5, ""},
		{"StdEncoding", Var, 0, ""},
		{"StdPadding", Const, 5, ""},
		{"URLEncoding", Var, 0, ""},
	},
	"encoding/binary": {
		{"(AppendByteOrder).AppendUint16", Method, 19, ""},
		{"(AppendByteOrder).AppendUint32", Method, 19, ""},
		{"(AppendByteOrder).AppendUint64", Method, 19, ""},
		{"(AppendByteOrder).String", Method, 19, ""},
		{"(ByteOrder).PutUint16", Method, 0, ""},
		{"(ByteOrder).PutUint32", Method, 0, ""},
		{"(ByteOrder).PutUint64", Method, 0, ""},
		{"(ByteOrder).String", Method, 0, ""},
		{"(ByteOrder).Uint16", Method, 0, ""},
		{"(ByteOrder).Uint32", Method, 0, ""},
		{"(ByteOrder).Uint64", Method, 0, ""},
		{"Append", Func, 23, "func(buf []byte, order ByteOrder, data any) ([]byte, error)"},
		{"AppendByteOrder", Type, 19, ""},
		{"AppendUvarint", Func, 19, "func(buf []byte, x uint64) []byte"},
		{"AppendVarint", Func, 19, "func(buf []byte, x int64) []byte"},
		{"BigEndian", Var, 0, ""},
		{"ByteOrder", Type, 0, ""},
		{"Decode", Func, 23, "func(buf []byte, order ByteOrder, data any) (int, error)"},
		{"Encode", Func, 23, "func(buf []byte, order ByteOrder, data any) (int, error)"},
		{"LittleEndian", Var, 0, ""},
		{"MaxVarintLen16", Const, 0, ""},
		{"MaxVarintLen32", Const, 0, ""},
		{"MaxVarintLen64", Const, 0, ""},
		{"NativeEndian", Var, 21, ""},
		{"PutUvarint", Func, 0, "func(buf []byte, x uint64) int"},
		{"PutVarint", Func, 0, "func(buf []byte, x int64) int"},
		{"Read", Func, 0, "func(r io.Reader, order ByteOrder, data any) error"},
		{"ReadUvarint", Func, 0, "func(r io.ByteReader) (uint64, error)"},
		{"ReadVarint", Func, 0, "func(r io.ByteReader) (int64, error)"},
		{"Size", Func, 0, "func(v any) int"},
		{"Uvarint", Func, 0, "func(buf []byte) (uint64, int)"},
		{"Varint", Func, 0, "func(buf []byte) (int64, int)"},
		{"Write", Func, 0, "func(w io.Writer, order ByteOrder, data any) error"},
	},
	"encoding/csv": {
		{"(*ParseError).Error", Method, 0, ""},
		{"(*ParseError).Unwrap", Method, 13, ""},
		{"(*Reader).FieldPos", Method, 17, ""},
		{"(*Reader).InputOffset", Method, 19, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Reader).ReadAll", Method, 0, ""},
		{"(*Writer).Error", Method, 1, ""},
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"(*Writer).WriteAll", Method, 0, ""},
		{"ErrBareQuote", Var, 0, ""},
		{"ErrFieldCount", Var, 0, ""},
		{"ErrQuote", Var, 0, ""},
		{"ErrTrailingComma", Var, 0, ""},
		{"NewReader", Func, 0, "func(r io.Reader) *Reader"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"ParseError", Type, 0, ""},
		{"ParseError.Column", Field, 0, ""},
		{"ParseError.Err", Field, 0, ""},
		{"ParseError.Line", Field, 0, ""},
		{"ParseError.StartLine", Field, 10, ""},
		{"Reader", Type, 0, ""},
		{"Reader.Comma", Field, 0, ""},
		{"Reader.Comment", Field, 0, ""},
		{"Reader.FieldsPerRecord", Field, 0, ""},
		{"Reader.LazyQuotes", Field, 0, ""},
		{"Reader.ReuseRecord", Field, 9, ""},
		{"Reader.TrailingComma", Field, 0, ""},
		{"Reader.TrimLeadingSpace", Field, 0, ""},
		{"Writer", Type, 0, ""},
		{"Writer.Comma", Field, 0, ""},
		{"Writer.UseCRLF", Field, 0, ""},
	},
	"encoding/gob": {
		{"(*Decoder).Decode", Method, 0, ""},
		{"(*Decoder).DecodeValue", Method, 0, ""},
		{"(*Encoder).Encode", Method, 0, ""},
		{"(*Encoder).EncodeValue", Method, 0, ""},
		{"(GobDecoder).GobDecode", Method, 0, ""},
		{"(GobEncoder).GobEncode", Method, 0, ""},
		{"CommonType", Type, 0, ""},
		{"CommonType.Id", Field, 0, ""},
		{"CommonType.Name", Field, 0, ""},
		{"Decoder", Type, 0, ""},
		{"Encoder", Type, 0, ""},
		{"GobDecoder", Type, 0, ""},
		{"GobEncoder", Type, 0, ""},
		{"NewDecoder", Func, 0, "func(r io.Reader) *Decoder"},
		{"NewEncoder", Func, 0, "func(w io.Writer) *Encoder"},
		{"Register", Func, 0, "func(value any)"},
		{"RegisterName", Func, 0, "func(name string, value any)"},
	},
	"encoding/hex": {
		{"(InvalidByteError).Error", Method, 0, ""},
		{"AppendDecode", Func, 22, "func(dst []byte, src []byte) ([]byte, error)"},
		{"AppendEncode", Func, 22, "func(dst []byte, src []byte) []byte"},
		{"Decode", Func, 0, "func(dst []byte, src []byte) (int, error)"},
		{"DecodeString", Func, 0, "func(s string) ([]byte, error)"},
		{"DecodedLen", Func, 0, "func(x int) int"},
		{"Dump", Func, 0, "func(data []byte) string"},
		{"Dumper", Func, 0, "func(w io.Writer) io.WriteCloser"},
		{"Encode", Func, 0, "func(dst []byte, src []byte) int"},
		{"EncodeToString", Func, 0, "func(src []byte) string"},
		{"EncodedLen", Func, 0, "func(n int) int"},
		{"ErrLength", Var, 0, ""},
		{"InvalidByteError", Type, 0, ""},
		{"NewDecoder", Func, 10, "func(r io.Reader) io.Reader"},
		{"NewEncoder", Func, 10, "func(w io.Writer) io.Writer"},
	},
	"encoding/json": {
		{"(*Decoder).Buffered", Method, 1, ""},
		{"(*Decoder).Decode", Method, 0, ""},
		{"(*Decoder).DisallowUnknownFields", Method, 10, ""},
		{"(*Decoder).InputOffset", Method, 14, ""},
		{"(*Decoder).More", Method, 5, ""},
		{"(*Decoder).Token", Method, 5, ""},
		{"(*Decoder).UseNumber", Method, 1, ""},
		{"(*Encoder).Encode", Method, 0, ""},
		{"(*Encoder).SetEscapeHTML", Method, 7, ""},
		{"(*Encoder).SetIndent", Method, 7, ""},
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		{"Attr", Type, 0, ""},
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		{"Attr.Value", Field, 0, ""},
		{"CharData", Type, 0, ""},
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		{"(*SendStmt).Pos", Method, 0, ""},
		{"(*SliceExpr).End", Method, 0, ""},
		{"(*SliceExpr).Pos", Method, 0, ""},
		{"(*StarExpr).End", Method, 0, ""},
		{"(*StarExpr).Pos", Method, 0, ""},
		{"(*StructType).End", Method, 0, ""},
		{"(*StructType).Pos", Method, 0, ""},
		{"(*SwitchStmt).End", Method, 0, ""},
		{"(*SwitchStmt).Pos", Method, 0, ""},
		{"(*TypeAssertExpr).End", Method, 0, ""},
		{"(*TypeAssertExpr).Pos", Method, 0, ""},
		{"(*TypeSpec).End", Method, 0, ""},
		{"(*TypeSpec).Pos", Method, 0, ""},
		{"(*TypeSwitchStmt).End", Method, 0, ""},
		{"(*TypeSwitchStmt).Pos", Method, 0, ""},
		{"(*UnaryExpr).End", Method, 0, ""},
		{"(*UnaryExpr).Pos", Method, 0, ""},
		{"(*ValueSpec).End", Method, 0, ""},
		{"(*ValueSpec).Pos", Method, 0, ""},
		{"(CommentMap).Comments", Method, 1, ""},
		{"(CommentMap).Filter", Method, 1, ""},
		{"(CommentMap).String", Method, 1, ""},
		{"(CommentMap).Update", Method, 1, ""},
		{"(Decl).End", Method, 0, ""},
		{"(Decl).Pos", Method, 0, ""},
		{"(Expr).End", Method, 0, ""},
		{"(Expr).Pos", Method, 0, ""},
		{"(Node).End", Method, 0, ""},
		{"(Node).Pos", Method, 0, ""},
		{"(ObjKind).String", Method, 0, ""},
		{"(Spec).End", Method, 0, ""},
		{"(Spec).Pos", Method, 0, ""},
		{"(Stmt).End", Method, 0, ""},
		{"(Stmt).Pos", Method, 0, ""},
		{"(Visitor).Visit", Method, 0, ""},
		{"ArrayType", Type, 0, ""},
		{"ArrayType.Elt", Field, 0, ""},
		{"ArrayType.Lbrack", Field, 0, ""},
		{"ArrayType.Len", Field, 0, ""},
		{"AssignStmt", Type, 0, ""},
		{"AssignStmt.Lhs", Field, 0, ""},
		{"AssignStmt.Rhs", Field, 0, ""},
		{"AssignStmt.Tok", Field, 0, ""},
		{"AssignStmt.TokPos", Field, 0, ""},
		{"Bad", Const, 0, ""},
		{"BadDecl", Type, 0, ""},
		{"BadDecl.From", Field, 0, ""},
		{"BadDecl.To", Field, 0, ""},
		{"BadExpr", Type, 0, ""},
		{"BadExpr.From", Field, 0, ""},
		{"BadExpr.To", Field, 0, ""},
		{"BadStmt", Type, 0, ""},
		{"BadStmt.From", Field, 0, ""},
		{"BadStmt.To", Field, 0, ""},
		{"BasicLit", Type, 0, ""},
		{"BasicLit.Kind", Field, 0, ""},
		{"BasicLit.Value", Field, 0, ""},
		{"BasicLit.ValueEnd", Field, 26, ""},
		{"BasicLit.ValuePos", Field, 0, ""},
		{"BinaryExpr", Type, 0, ""},
		{"BinaryExpr.Op", Field, 0, ""},
		{"BinaryExpr.OpPos", Field, 0, ""},
		{"BinaryExpr.X", Field, 0, ""},
		{"BinaryExpr.Y", Field, 0, ""},
		{"BlockStmt", Type, 0, ""},
		{"BlockStmt.Lbrace", Field, 0, ""},
		{"BlockStmt.List", Field, 0, ""},
		{"BlockStmt.Rbrace", Field, 0, ""},
		{"BranchStmt", Type, 0, ""},
		{"BranchStmt.Label", Field, 0, ""},
		{"BranchStmt.Tok", Field, 0, ""},
		{"BranchStmt.TokPos", Field, 0, ""},
		{"CallExpr", Type, 0, ""},
		{"CallExpr.Args", Field, 0, ""},
		{"CallExpr.Ellipsis", Field, 0, ""},
		{"CallExpr.Fun", Field, 0, ""},
		{"CallExpr.Lparen", Field, 0, ""},
		{"CallExpr.Rparen", Field, 0, ""},
		{"CaseClause", Type, 0, ""},
		{"CaseClause.Body", Field, 0, ""},
		{"CaseClause.Case", Field, 0, ""},
		{"CaseClause.Colon", Field, 0, ""},
		{"CaseClause.List", Field, 0, ""},
		{"ChanDir", Type, 0, ""},
		{"ChanType", Type, 0, ""},
		{"ChanType.Arrow", Field, 1, ""},
		{"ChanType.Begin", Field, 0, ""},
		{"ChanType.Dir", Field, 0, ""},
		{"ChanType.Value", Field, 0, ""},
		{"CommClause", Type, 0, ""},
		{"CommClause.Body", Field, 0, ""},
		{"CommClause.Case", Field, 0, ""},
		{"CommClause.Colon", Field, 0, ""},
		{"CommClause.Comm", Field, 0, ""},
		{"Comment", Type, 0, ""},
		{"Comment.Slash", Field, 0, ""},
		{"Comment.Text", Field, 0, ""},
		{"CommentGroup", Type, 0, ""},
		{"CommentGroup.List", Field, 0, ""},
		{"CommentMap", Type, 1, ""},
		{"CompositeLit", Type, 0, ""},
		{"CompositeLit.Elts", Field, 0, ""},
		{"CompositeLit.Incomplete", Field, 11, ""},
		{"CompositeLit.Lbrace", Field, 0, ""},
		{"CompositeLit.Rbrace", Field, 0, ""},
		{"CompositeLit.Type", Field, 0, ""},
		{"Con", Const, 0, ""},
		{"DeclStmt", Type, 0, ""},
		{"DeclStmt.Decl", Field, 0, ""},
		{"DeferStmt", Type, 0, ""},
		{"DeferStmt.Call", Field, 0, ""},
		{"DeferStmt.Defer", Field, 0, ""},
		{"Directive", Type, 26, ""},
		{"Directive.Args", Field, 26, ""},
		{"Directive.ArgsPos", Field, 26, ""},
		{"Directive.Name", Field, 26, ""},
		{"Directive.Slash", Field, 26, ""},
		{"Directive.Tool", Field, 26, ""},
		{"DirectiveArg", Type, 26, ""},
		{"DirectiveArg.Arg", Field, 26, ""},
		{"DirectiveArg.Pos", Field, 26, ""},
		{"Ellipsis", Type, 0, ""},
		{"Ellipsis.Ellipsis", Field, 0, ""},
		{"Ellipsis.Elt", Field, 0, ""},
		{"EmptyStmt", Type, 0, ""},
		{"EmptyStmt.Implicit", Field, 5, ""},
		{"EmptyStmt.Semicolon", Field, 0, ""},
		{"ExprStmt", Type, 0, ""},
		{"ExprStmt.X", Field, 0, ""},
		{"Field", Type, 0, ""},
		{"Field.Comment", Field, 0, ""},
		{"Field.Doc", Field, 0, ""},
		{"Field.Names", Field, 0, ""},
		{"Field.Tag", Field, 0, ""},
		{"Field.Type", Field, 0, ""},
		{"FieldFilter", Type, 0, ""},
		{"FieldList", Type, 0, ""},
		{"FieldList.Closing", Field, 0, ""},
		{"FieldList.List", Field, 0, ""},
		{"FieldList.Opening", Field, 0, ""},
		{"File", Type, 0, ""},
		{"File.Comments", Field, 0, ""},
		{"File.Decls", Field, 0, ""},
		{"File.Doc", Field, 0, ""},
		{"File.FileEnd", Field, 20, ""},
		{"File.FileStart", Field, 20, ""},
		{"File.GoVersion", Field, 21, ""},
		{"File.Imports", Field, 0, ""},
		{"File.Name", Field, 0, ""},
		{"File.Package", Field, 0, ""},
		{"File.Scope", Field, 0, ""},
		{"File.Unresolved", Field, 0, ""},
		{"FileExports", Func, 0, "func(src *File) bool"},
		{"Filter", Type, 0, ""},
		{"FilterDecl", Func, 0, "func(decl Decl, f Filter) bool"},
		{"FilterFile", Func, 0, "func(src *File, f Filter) bool"},
		{"FilterFuncDuplicates", Const, 0, ""},
		{"FilterImportDuplicates", Const, 0, ""},
		{"FilterPackage", Func, 0, "func(pkg *Package, f Filter) bool"},
		{"FilterUnassociatedComments", Const, 0, ""},
		{"ForStmt", Type, 0, ""},
		{"ForStmt.Body", Field, 0, ""},
		{"ForStmt.Cond", Field, 0, ""},
		{"ForStmt.For", Field, 0, ""},
		{"ForStmt.Init", Field, 0, ""},
		{"ForStmt.Post", Field, 0, ""},
		{"Fprint", Func, 0, "func(w io.Writer, fset *token.FileSet, x any, f FieldFilter) error"},
		{"Fun", Const, 0, ""},
		{"FuncDecl", Type, 0, ""},
		{"FuncDecl.Body", Field, 0, ""},
		{"FuncDecl.Doc", Field, 0, ""},
		{"FuncDecl.Name", Field, 0, ""},
		{"FuncDecl.Recv", Field, 0, ""},
		{"FuncDecl.Type", Field, 0, ""},
		{"FuncLit", Type, 0, ""},
		{"FuncLit.Body", Field, 0, ""},
		{"FuncLit.Type", Field, 0, ""},
		{"FuncType", Type, 0, ""},
		{"FuncType.Func", Field, 0, ""},
		{"FuncType.Params", Field, 0, ""},
		{"FuncType.Results", Field, 0, ""},
		{"FuncType.TypeParams", Field, 18, ""},
		{"GenDecl", Type, 0, ""},
		{"GenDecl.Doc", Field, 0, ""},
		{"GenDecl.Lparen", Field, 0, ""},
		{"GenDecl.Rparen", Field, 0, ""},
		{"GenDecl.Specs", Field, 0, ""},
		{"GenDecl.Tok", Field, 0, ""},
		{"GenDecl.TokPos", Field, 0, ""},
		{"GoStmt", Type, 0, ""},
		{"GoStmt.Call", Field, 0, ""},
		{"GoStmt.Go", Field, 0, ""},
		{"Ident", Type, 0, ""},
		{"Ident.Name", Field, 0, ""},
		{"Ident.NamePos", Field, 0, ""},
		{"Ident.Obj", Field, 0, ""},
		{"IfStmt", Type, 0, ""},
		{"IfStmt.Body", Field, 0, ""},
		{"IfStmt.Cond", Field, 0, ""},
		{"IfStmt.Else", Field, 0, ""},
		{"IfStmt.If", Field, 0, ""},
		{"IfStmt.Init", Field, 0, ""},
		{"ImportSpec", Type, 0, ""},
		{"ImportSpec.Comment", Field, 0, ""},
		{"ImportSpec.Doc", Field, 0, ""},
		{"ImportSpec.EndPos", Field, 0, ""},
		{"ImportSpec.Name", Field, 0, ""},
		{"ImportSpec.Path", Field, 0, ""},
		{"Importer", Type, 0, ""},
		{"IncDecStmt", Type, 0, ""},
		{"IncDecStmt.Tok", Field, 0, ""},
		{"IncDecStmt.TokPos", Field, 0, ""},
		{"IncDecStmt.X", Field, 0, ""},
		{"IndexExpr", Type, 0, ""},
		{"IndexExpr.Index", Field, 0, ""},
		{"IndexExpr.Lbrack", Field, 0, ""},
		{"IndexExpr.Rbrack", Field, 0, ""},
		{"IndexExpr.X", Field, 0, ""},
		{"IndexListExpr", Type, 18, ""},
		{"IndexListExpr.Indices", Field, 18, ""},
		{"IndexListExpr.Lbrack", Field, 18, ""},
		{"IndexListExpr.Rbrack", Field, 18, ""},
		{"IndexListExpr.X", Field, 18, ""},
		{"Inspect", Func, 0, "func(node Node, f func(Node) bool)"},
		{"InterfaceType", Type, 0, ""},
		{"InterfaceType.Incomplete", Field, 0, ""},
		{"InterfaceType.Interface", Field, 0, ""},
		{"InterfaceType.Methods", Field, 0, ""},
		{"IsExported", Func, 0, "func(name string) bool"},
		{"IsGenerated", Func, 21, "func(file *File) bool"},
		{"KeyValueExpr", Type, 0, ""},
		{"KeyValueExpr.Colon", Field, 0, ""},
		{"KeyValueExpr.Key", Field, 0, ""},
		{"KeyValueExpr.Value", Field, 0, ""},
		{"LabeledStmt", Type, 0, ""},
		{"LabeledStmt.Colon", Field, 0, ""},
		{"LabeledStmt.Label", Field, 0, ""},
		{"LabeledStmt.Stmt", Field, 0, ""},
		{"Lbl", Const, 0, ""},
		{"MapType", Type, 0, ""},
		{"MapType.Key", Field, 0, ""},
		{"MapType.Map", Field, 0, ""},
		{"MapType.Value", Field, 0, ""},
		{"MergeMode", Type, 0, ""},
		{"MergePackageFiles", Func, 0, "func(pkg *Package, mode MergeMode) *File"},
		{"NewCommentMap", Func, 1, "func(fset *token.FileSet, node Node, comments []*CommentGroup) CommentMap"},
		{"NewIdent", Func, 0, "func(name string) *Ident"},
		{"NewObj", Func, 0, "func(kind ObjKind, name string) *Object"},
		{"NewPackage", Func, 0, "func(fset *token.FileSet, files map[string]*File, importer Importer, universe *Scope) (*Package, error)"},
		{"NewScope", Func, 0, "func(outer *Scope) *Scope"},
		{"Node", Type, 0, ""},
		{"NotNilFilter", Func, 0, "func(_ string, v reflect.Value) bool"},
		{"ObjKind", Type, 0, ""},
		{"Object", Type, 0, ""},
		{"Object.Data", Field, 0, ""},
		{"Object.Decl", Field, 0, ""},
		{"Object.Kind", Field, 0, ""},
		{"Object.Name", Field, 0, ""},
		{"Object.Type", Field, 0, ""},
		{"Package", Type, 0, ""},
		{"Package.Files", Field, 0, ""},
		{"Package.Imports", Field, 0, ""},
		{"Package.Name", Field, 0, ""},
		{"Package.Scope", Field, 0, ""},
		{"PackageExports", Func, 0, "func(pkg *Package) bool"},
		{"ParenExpr", Type, 0, ""},
		{"ParenExpr.Lparen", Field, 0, ""},
		{"ParenExpr.Rparen", Field, 0, ""},
		{"ParenExpr.X", Field, 0, ""},
		{"ParseDirective", Func, 26, "func(pos token.Pos, c string) (Directive, bool)"},
		{"Pkg", Const, 0, ""},
		{"Preorder", Func, 23, "func(root Node) iter.Seq[Node]"},
		{"PreorderStack", Func, 25, "func(root Node, stack []Node, f func(n Node, stack []Node) bool)"},
		{"Print", Func, 0, "func(fset *token.FileSet, x any) error"},
		{"RECV", Const, 0, ""},
		{"RangeStmt", Type, 0, ""},
		{"RangeStmt.Body", Field, 0, ""},
		{"RangeStmt.For", Field, 0, ""},
		{"RangeStmt.Key", Field, 0, ""},
		{"RangeStmt.Range", Field, 20, ""},
		{"RangeStmt.Tok", Field, 0, ""},
		{"RangeStmt.TokPos", Field, 0, ""},
		{"RangeStmt.Value", Field, 0, ""},
		{"RangeStmt.X", Field, 0, ""},
		{"ReturnStmt", Type, 0, ""},
		{"ReturnStmt.Results", Field, 0, ""},
		{"ReturnStmt.Return", Field, 0, ""},
		{"SEND", Const, 0, ""},
		{"Scope", Type, 0, ""},
		{"Scope.Objects", Field, 0, ""},
		{"Scope.Outer", Field, 0, ""},
		{"SelectStmt", Type, 0, ""},
		{"SelectStmt.Body", Field, 0, ""},
		{"SelectStmt.Select", Field, 0, ""},
		{"SelectorExpr", Type, 0, ""},
		{"SelectorExpr.Sel", Field, 0, ""},
		{"SelectorExpr.X", Field, 0, ""},
		{"SendStmt", Type, 0, ""},
		{"SendStmt.Arrow", Field, 0, ""},
		{"SendStmt.Chan", Field, 0, ""},
		{"SendStmt.Value", Field, 0, ""},
		{"SliceExpr", Type, 0, ""},
		{"SliceExpr.High", Field, 0, ""},
		{"SliceExpr.Lbrack", Field, 0, ""},
		{"SliceExpr.Low", Field, 0, ""},
		{"SliceExpr.Max", Field, 2, ""},
		{"SliceExpr.Rbrack", Field, 0, ""},
		{"SliceExpr.Slice3", Field, 2, ""},
		{"SliceExpr.X", Field, 0, ""},
		{"SortImports", Func, 0, "func(fset *token.FileSet, f *File)"},
		{"StarExpr", Type, 0, ""},
		{"StarExpr.Star", Field, 0, ""},
		{"StarExpr.X", Field, 0, ""},
		{"StructType", Type, 0, ""},
		{"StructType.Fields", Field, 0, ""},
		{"StructType.Incomplete", Field, 0, ""},
		{"StructType.Struct", Field, 0, ""},
		{"SwitchStmt", Type, 0, ""},
		{"SwitchStmt.Body", Field, 0, ""},
		{"SwitchStmt.Init", Field, 0, ""},
		{"SwitchStmt.Switch", Field, 0, ""},
		{"SwitchStmt.Tag", Field, 0, ""},
		{"Typ", Const, 0, ""},
		{"TypeAssertExpr", Type, 0, ""},
		{"TypeAssertExpr.Lparen", Field, 2, ""},
		{"TypeAssertExpr.Rparen", Field, 2, ""},
		{"TypeAssertExpr.Type", Field, 0, ""},
		{"TypeAssertExpr.X", Field, 0, ""},
		{"TypeSpec", Type, 0, ""},
		{"TypeSpec.Assign", Field, 9, ""},
		{"TypeSpec.Comment", Field, 0, ""},
		{"TypeSpec.Doc", Field, 0, ""},
		{"TypeSpec.Name", Field, 0, ""},
		{"TypeSpec.Type", Field, 0, ""},
		{"TypeSpec.TypeParams", Field, 18, ""},
		{"TypeSwitchStmt", Type, 0, ""},
		{"TypeSwitchStmt.Assign", Field, 0, ""},
		{"TypeSwitchStmt.Body", Field, 0, ""},
		{"TypeSwitchStmt.Init", Field, 0, ""},
		{"TypeSwitchStmt.Switch", Field, 0, ""},
		{"UnaryExpr", Type, 0, ""},
		{"UnaryExpr.Op", Field, 0, ""},
		{"UnaryExpr.OpPos", Field, 0, ""},
		{"UnaryExpr.X", Field, 0, ""},
		{"Unparen", Func, 22, "func(e Expr) Expr"},
		{"ValueSpec", Type, 0, ""},
		{"ValueSpec.Comment", Field, 0, ""},
		{"ValueSpec.Doc", Field, 0, ""},
		{"ValueSpec.Names", Field, 0, ""},
		{"ValueSpec.Type", Field, 0, ""},
		{"ValueSpec.Values", Field, 0, ""},
		{"Var", Const, 0, ""},
		{"Visitor", Type, 0, ""},
		{"Walk", Func, 0, "func(v Visitor, node Node)"},
	},
	"go/build": {
		{"(*Context).Import", Method, 0, ""},
		{"(*Context).ImportDir", Method, 0, ""},
		{"(*Context).MatchFile", Method, 2, ""},
		{"(*Context).SrcDirs", Method, 0, ""},
		{"(*MultiplePackageError).Error", Method, 4, ""},
		{"(*NoGoError).Error", Method, 0, ""},
		{"(*Package).IsCommand", Method, 0, ""},
		{"AllowBinary", Const, 0, ""},
		{"ArchChar", Func, 0, "func(goarch string) (string, error)"},
		{"Context", Type, 0, ""},
		{"Context.BuildTags", Field, 0, ""},
		{"Context.CgoEnabled", Field, 0, ""},
		{"Context.Compiler", Field, 0, ""},
		{"Context.Dir", Field, 14, ""},
		{"Context.GOARCH", Field, 0, ""},
		{"Context.GOOS", Field, 0, ""},
		{"Context.GOPATH", Field, 0, ""},
		{"Context.GOROOT", Field, 0, ""},
		{"Context.HasSubdir", Field, 0, ""},
		{"Context.InstallSuffix", Field, 1, ""},
		{"Context.IsAbsPath", Field, 0, ""},
		{"Context.IsDir", Field, 0, ""},
		{"Context.JoinPath", Field, 0, ""},
		{"Context.OpenFile", Field, 0, ""},
		{"Context.ReadDir", Field, 0, ""},
		{"Context.ReleaseTags", Field, 1, ""},
		{"Context.SplitPathList", Field, 0, ""},
		{"Context.ToolTags", Field, 17, ""},
		{"Context.UseAllFiles", Field, 0, ""},
		{"Default", Var, 0, ""},
		{"Directive", Type, 21, ""},
		{"Directive.Pos", Field, 21, ""},
		{"Directive.Text", Field, 21, ""},
		{"FindOnly", Const, 0, ""},
		{"IgnoreVendor", Const, 6, ""},
		{"Import", Func, 0, "func(path string, srcDir string, mode ImportMode) (*Package, error)"},
		{"ImportComment", Const, 4, ""},
		{"ImportDir", Func, 0, "func(dir string, mode ImportMode) (*Package, error)"},
		{"ImportMode", Type, 0, ""},
		{"IsLocalImport", Func, 0, "func(path string) bool"},
		{"MultiplePackageError", Type, 4, ""},
		{"MultiplePackageError.Dir", Field, 4, ""},
		{"MultiplePackageError.Files", Field, 4, ""},
		{"MultiplePackageError.Packages", Field, 4, ""},
		{"NoGoError", Type, 0, ""},
		{"NoGoError.Dir", Field, 0, ""},
		{"Package", Type, 0, ""},
		{"Package.AllTags", Field, 2, ""},
		{"Package.BinDir", Field, 0, ""},
		{"Package.BinaryOnly", Field, 7, ""},
		{"Package.CFiles", Field, 0, ""},
		{"Package.CXXFiles", Field, 2, ""},
		{"Package.CgoCFLAGS", Field, 0, ""},
		{"Package.CgoCPPFLAGS", Field, 2, ""},
		{"Package.CgoCXXFLAGS", Field, 2, ""},
		{"Package.CgoFFLAGS", Field, 7, ""},
		{"Package.CgoFiles", Field, 0, ""},
		{"Package.CgoLDFLAGS", Field, 0, ""},
		{"Package.CgoPkgConfig", Field, 0, ""},
		{"Package.ConflictDir", Field, 2, ""},
		{"Package.Dir", Field, 0, ""},
		{"Package.Directives", Field, 21, ""},
		{"Package.Doc", Field, 0, ""},
		{"Package.EmbedPatternPos", Field, 16, ""},
		{"Package.EmbedPatterns", Field, 16, ""},
		{"Package.FFiles", Field, 7, ""},
		{"Package.GoFiles", Field, 0, ""},
		{"Package.Goroot", Field, 0, ""},
		{"Package.HFiles", Field, 0, ""},
		{"Package.IgnoredGoFiles", Field, 1, ""},
		{"Package.IgnoredOtherFiles", Field, 16, ""},
		{"Package.ImportComment", Field, 4, ""},
		{"Package.ImportPath", Field, 0, ""},
		{"Package.ImportPos", Field, 0, ""},
		{"Package.Imports", Field, 0, ""},
		{"Package.InvalidGoFiles", Field, 6, ""},
		{"Package.MFiles", Field, 3, ""},
		{"Package.Name", Field, 0, ""},
		{"Package.PkgObj", Field, 0, ""},
		{"Package.PkgRoot", Field, 0, ""},
		{"Package.PkgTargetRoot", Field, 5, ""},
		{"Package.Root", Field, 0, ""},
		{"Package.SFiles", Field, 0, ""},
		{"Package.SrcRoot", Field, 0, ""},
		{"Package.SwigCXXFiles", Field, 1, ""},
		{"Package.SwigFiles", Field, 1, ""},
		{"Package.SysoFiles", Field, 0, ""},
		{"Package.TestDirectives", Field, 21, ""},
		{"Package.TestEmbedPatternPos", Field, 16, ""},
		{"Package.TestEmbedPatterns", Field, 16, ""},
		{"Package.TestGoFiles", Field, 0, ""},
		{"Package.TestImportPos", Field, 0, ""},
		{"Package.TestImports", Field, 0, ""},
		{"Package.XTestDirectives", Field, 21, ""},
		{"Package.XTestEmbedPatternPos", Field, 16, ""},
		{"Package.XTestEmbedPatterns", Field, 16, ""},
		{"Package.XTestGoFiles", Field, 0, ""},
		{"Package.XTestImportPos", Field, 0, ""},
		{"Package.XTestImports", Field, 0, ""},
		{"ToolDir", Var, 0, ""},
	},
	"go/build/constraint": {
		{"(*AndExpr).Eval", Method, 16, ""},
		{"(*AndExpr).String", Method, 16, ""},
		{"(*NotExpr).Eval", Method, 16, ""},
		{"(*NotExpr).String", Method, 16, ""},
		{"(*OrExpr).Eval", Method, 16, ""},
		{"(*OrExpr).String", Method, 16, ""},
		{"(*SyntaxError).Error", Method, 16, ""},
		{"(*TagExpr).Eval", Method, 16, ""},
		{"(*TagExpr).String", Method, 16, ""},
		{"(Expr).Eval", Method, 16, ""},
		{"(Expr).String", Method, 16, ""},
		{"AndExpr", Type, 16, ""},
		{"AndExpr.X", Field, 16, ""},
		{"AndExpr.Y", Field, 16, ""},
		{"GoVersion", Func, 21, "func(x Expr) string"},
		{"IsGoBuild", Func, 16, "func(line string) bool"},
		{"IsPlusBuild", Func, 16, "func(line string) bool"},
		{"NotExpr", Type, 16, ""},
		{"NotExpr.X", Field, 16, ""},
		{"OrExpr", Type, 16, ""},
		{"OrExpr.X", Field, 16, ""},
		{"OrExpr.Y", Field, 16, ""},
		{"Parse", Func, 16, "func(line string) (Expr, error)"},
		{"PlusBuildLines", Func, 16, "func(x Expr) ([]string, error)"},
		{"SyntaxError", Type, 16, ""},
		{"SyntaxError.Err", Field, 16, ""},
		{"SyntaxError.Offset", Field, 16, ""},
		{"TagExpr", Type, 16, ""},
		{"TagExpr.Tag", Field, 16, ""},
	},
	"go/constant": {
		{"(Kind).String", Method, 18, ""},
		{"(Value).ExactString", Method, 6, ""},
		{"(Value).Kind", Method, 5, ""},
		{"(Value).String", Method, 5, ""},
		{"BinaryOp", Func, 5, "func(x_ Value, op token.Token, y_ Value) Value"},
		{"BitLen", Func, 5, "func(x Value) int"},
		{"Bool", Const, 5, ""},
		{"BoolVal", Func, 5, "func(x Value) bool"},
		{"Bytes", Func, 5, "func(x Value) []byte"},
		{"Compare", Func, 5, "func(x_ Value, op token.Token, y_ Value) bool"},
		{"Complex", Const, 5, ""},
		{"Denom", Func, 5, "func(x Value) Value"},
		{"Float", Const, 5, ""},
		{"Float32Val", Func, 5, "func(x Value) (float32, bool)"},
		{"Float64Val", Func, 5, "func(x Value) (float64, bool)"},
		{"Imag", Func, 5, "func(x Value) Value"},
		{"Int", Const, 5, ""},
		{"Int64Val", Func, 5, "func(x Value) (int64, bool)"},
		{"Kind", Type, 5, ""},
		{"Make", Func, 13, "func(x any) Value"},
		{"MakeBool", Func, 5, "func(b bool) Value"},
		{"MakeFloat64", Func, 5, "func(x float64) Value"},
		{"MakeFromBytes", Func, 5, "func(bytes []byte) Value"},
		{"MakeFromLiteral", Func, 5, "func(lit string, tok token.Token, zero uint) Value"},
		{"MakeImag", Func, 5, "func(x Value) Value"},
		{"MakeInt64", Func, 5, "func(x int64) Value"},
		{"MakeString", Func, 5, "func(s string) Value"},
		{"MakeUint64", Func, 5, "func(x uint64) Value"},
		{"MakeUnknown", Func, 5, "func() Value"},
		{"Num", Func, 5, "func(x Value) Value"},
		{"Real", Func, 5, "func(x Value) Value"},
		{"Shift", Func, 5, "func(x Value, op token.Token, s uint) Value"},
		{"Sign", Func, 5, "func(x Value) int"},
		{"String", Const, 5, ""},
		{"StringVal", Func, 5, "func(x Value) string"},
		{"ToComplex", Func, 6, "func(x Value) Value"},
		{"ToFloat", Func, 6, "func(x Value) Value"},
		{"ToInt", Func, 6, "func(x Value) Value"},
		{"Uint64Val", Func, 5, "func(x Value) (uint64, bool)"},
		{"UnaryOp", Func, 5, "func(op token.Token, y Value, prec uint) Value"},
		{"Unknown", Const, 5, ""},
		{"Val", Func, 13, "func(x Value) any"},
	},
	"go/doc": {
		{"(*Package).Filter", Method, 0, ""},
		{"(*Package).HTML", Method, 19, ""},
		{"(*Package).Markdown", Method, 19, ""},
		{"(*Package).Parser", Method, 19, ""},
		{"(*Package).Printer", Method, 19, ""},
		{"(*Package).Synopsis", Method, 19, ""},
		{"(*Package).Text", Method, 19, ""},
		{"AllDecls", Const, 0, ""},
		{"AllMethods", Const, 0, ""},
		{"Example", Type, 0, ""},
		{"Example.Code", Field, 0, ""},
		{"Example.Comments", Field, 0, ""},
		{"Example.Doc", Field, 0, ""},
		{"Example.EmptyOutput", Field, 1, ""},
		{"Example.Name", Field, 0, ""},
		{"Example.Order", Field, 1, ""},
		{"Example.Output", Field, 0, ""},
		{"Example.Play", Field, 1, ""},
		{"Example.Suffix", Field, 14, ""},
		{"Example.Unordered", Field, 7, ""},
		{"Examples", Func, 0, "func(testFiles ...*ast.File) []*Example"},
		{"Filter", Type, 0, ""},
		{"Func", Type, 0, ""},
		{"Func.Decl", Field, 0, ""},
		{"Func.Doc", Field, 0, ""},
		{"Func.Examples", Field, 14, ""},
		{"Func.Level", Field, 0, ""},
		{"Func.Name", Field, 0, ""},
		{"Func.Orig", Field, 0, ""},
		{"Func.Recv", Field, 0, ""},
		{"IllegalPrefixes", Var, 1, ""},
		{"IsPredeclared", Func, 8, "func(s string) bool"},
		{"Mode", Type, 0, ""},
		{"New", Func, 0, "func(pkg *ast.Package, importPath string, mode Mode) *Package"},
		{"NewFromFiles", Func, 14, "func(fset *token.FileSet, files []*ast.File, importPath string, opts ...any) (*Package, error)"},
		{"Note", Type, 1, ""},
		{"Note.Body", Field, 1, ""},
		{"Note.End", Field, 1, ""},
		{"Note.Pos", Field, 1, ""},
		{"Note.UID", Field, 1, ""},
		{"Package", Type, 0, ""},
		{"Package.Bugs", Field, 0, ""},
		{"Package.Consts", Field, 0, ""},
		{"Package.Doc", Field, 0, ""},
		{"Package.Examples", Field, 14, ""},
		{"Package.Filenames", Field, 0, ""},
		{"Package.Funcs", Field, 0, ""},
		{"Package.ImportPath", Field, 0, ""},
		{"Package.Imports", Field, 0, ""},
		{"Package.Name", Field, 0, ""},
		{"Package.Notes", Field, 1, ""},
		{"Package.Types", Field, 0, ""},
		{"Package.Vars", Field, 0, ""},
		{"PreserveAST", Const, 12, ""},
		{"Synopsis", Func, 0, "func(text string) string"},
		{"ToHTML", Func, 0, "func(w io.Writer, text string, words map[string]string)"},
		{"ToText", Func, 0, "func(w io.Writer, text string, prefix string, codePrefix string, width int)"},
		{"Type", Type, 0, ""},
		{"Type.Consts", Field, 0, ""},
		{"Type.Decl", Field, 0, ""},
		{"Type.Doc", Field, 0, ""},
		{"Type.Examples", Field, 14, ""},
		{"Type.Funcs", Field, 0, ""},
		{"Type.Methods", Field, 0, ""},
		{"Type.Name", Field, 0, ""},
		{"Type.Vars", Field, 0, ""},
		{"Value", Type, 0, ""},
		{"Value.Decl", Field, 0, ""},
		{"Value.Doc", Field, 0, ""},
		{"Value.Names", Field, 0, ""},
	},
	"go/doc/comment": {
		{"(*DocLink).DefaultURL", Method, 19, ""},
		{"(*Heading).DefaultID", Method, 19, ""},
		{"(*List).BlankBefore", Method, 19, ""},
		{"(*List).BlankBetween", Method, 19, ""},
		{"(*Parser).Parse", Method, 19, ""},
		{"(*Printer).Comment", Method, 19, ""},
		{"(*Printer).HTML", Method, 19, ""},
		{"(*Printer).Markdown", Method, 19, ""},
		{"(*Printer).Text", Method, 19, ""},
		{"Code", Type, 19, ""},
		{"Code.Text", Field, 19, ""},
		{"DefaultLookupPackage", Func, 19, "func(name string) (importPath string, ok bool)"},
		{"Doc", Type, 19, ""},
		{"Doc.Content", Field, 19, ""},
		{"Doc.Links", Field, 19, ""},
		{"DocLink", Type, 19, ""},
		{"DocLink.ImportPath", Field, 19, ""},
		{"DocLink.Name", Field, 19, ""},
		{"DocLink.Recv", Field, 19, ""},
		{"DocLink.Text", Field, 19, ""},
		{"Heading", Type, 19, ""},
		{"Heading.Text", Field, 19, ""},
		{"Italic", Type, 19, ""},
		{"Link", Type, 19, ""},
		{"Link.Auto", Field, 19, ""},
		{"Link.Text", Field, 19, ""},
		{"Link.URL", Field, 19, ""},
		{"LinkDef", Type, 19, ""},
		{"LinkDef.Text", Field, 19, ""},
		{"LinkDef.URL", Field, 19, ""},
		{"LinkDef.Used", Field, 19, ""},
		{"List", Type, 19, ""},
		{"List.ForceBlankBefore", Field, 19, ""},
		{"List.ForceBlankBetween", Field, 19, ""},
		{"List.Items", Field, 19, ""},
		{"ListItem", Type, 19, ""},
		{"ListItem.Content", Field, 19, ""},
		{"ListItem.Number", Field, 19, ""},
		{"Paragraph", Type, 19, ""},
		{"Paragraph.Text", Field, 19, ""},
		{"Parser", Type, 19, ""},
		{"Parser.LookupPackage", Field, 19, ""},
		{"Parser.LookupSym", Field, 19, ""},
		{"Parser.Words", Field, 19, ""},
		{"Plain", Type, 19, ""},
		{"Printer", Type, 19, ""},
		{"Printer.DocLinkBaseURL", Field, 19, ""},
		{"Printer.DocLinkURL", Field, 19, ""},
		{"Printer.HeadingID", Field, 19, ""},
		{"Printer.HeadingLevel", Field, 19, ""},
		{"Printer.TextCodePrefix", Field, 19, ""},
		{"Printer.TextPrefix", Field, 19, ""},
		{"Printer.TextWidth", Field, 19, ""},
	},
	"go/format": {
		{"Node", Func, 1, "func(dst io.Writer, fset *token.FileSet, node any) error"},
		{"Source", Func, 1, "func(src []byte) ([]byte, error)"},
	},
	"go/importer": {
		{"Default", Func, 5, "func() types.Importer"},
		{"For", Func, 5, "func(compiler string, lookup Lookup) types.Importer"},
		{"ForCompiler", Func, 12, "func(fset *token.FileSet, compiler string, lookup Lookup) types.Importer"},
		{"Lookup", Type, 5, ""},
	},
	"go/parser": {
		{"AllErrors", Const, 1, ""},
		{"DeclarationErrors", Const, 0, ""},
		{"ImportsOnly", Const, 0, ""},
		{"Mode", Type, 0, ""},
		{"PackageClauseOnly", Const, 0, ""},
		{"ParseComments", Const, 0, ""},
		{"ParseDir", Func, 0, "func(fset *token.FileSet, path string, filter func(fs.FileInfo) bool, mode Mode) (pkgs map[string]*ast.Package, first error)"},
		{"ParseExpr", Func, 0, "func(x string) (ast.Expr, error)"},
		{"ParseExprFrom", Func, 5, "func(fset *token.FileSet, filename string, src any, mode Mode) (expr ast.Expr, err error)"},
		{"ParseFile", Func, 0, "func(fset *token.FileSet, filename string, src any, mode Mode) (f *ast.File, err error)"},
		{"SkipObjectResolution", Const, 17, ""},
		{"SpuriousErrors", Const, 0, ""},
		{"Trace", Const, 0, ""},
	},
	"go/printer": {
		{"(*Config).Fprint", Method, 0, ""},
		{"CommentedNode", Type, 0, ""},
		{"CommentedNode.Comments", Field, 0, ""},
		{"CommentedNode.Node", Field, 0, ""},
		{"Config", Type, 0, ""},
		{"Config.Indent", Field, 1, ""},
		{"Config.Mode", Field, 0, ""},
		{"Config.Tabwidth", Field, 0, ""},
		{"Fprint", Func, 0, "func(output io.Writer, fset *token.FileSet, node any) error"},
		{"Mode", Type, 0, ""},
		{"RawFormat", Const, 0, ""},
		{"SourcePos", Const, 0, ""},
		{"TabIndent", Const, 0, ""},
		{"UseSpaces", Const, 0, ""},
	},
	"go/scanner": {
		{"(*ErrorList).Add", Method, 0, ""},
		{"(*ErrorList).RemoveMultiples", Method, 0, ""},
		{"(*ErrorList).Reset", Method, 0, ""},
		{"(*Scanner).Init", Method, 0, ""},
		{"(*Scanner).Scan", Method, 0, ""},
		{"(Error).Error", Method, 0, ""},
		{"(ErrorList).Err", Method, 0, ""},
		{"(ErrorList).Error", Method, 0, ""},
		{"(ErrorList).Len", Method, 0, ""},
		{"(ErrorList).Less", Method, 0, ""},
		{"(ErrorList).Sort", Method, 0, ""},
		{"(ErrorList).Swap", Method, 0, ""},
		{"Error", Type, 0, ""},
		{"Error.Msg", Field, 0, ""},
		{"Error.Pos", Field, 0, ""},
		{"ErrorHandler", Type, 0, ""},
		{"ErrorList", Type, 0, ""},
		{"Mode", Type, 0, ""},
		{"PrintError", Func, 0, "func(w io.Writer, err error)"},
		{"ScanComments", Const, 0, ""},
		{"Scanner", Type, 0, ""},
		{"Scanner.ErrorCount", Field, 0, ""},
	},
	"go/token": {
		{"(*File).AddLine", Method, 0, ""},
		{"(*File).AddLineColumnInfo", Method, 11, ""},
		{"(*File).AddLineInfo", Method, 0, ""},
		{"(*File).Base", Method, 0, ""},
		{"(*File).End", Method, 26, ""},
		{"(*File).Line", Method, 0, ""},
		{"(*File).LineCount", Method, 0, ""},
		{"(*File).LineStart", Method, 12, ""},
		{"(*File).Lines", Method, 21, ""},
		{"(*File).MergeLine", Method, 2, ""},
		{"(*File).Name", Method, 0, ""},
		{"(*File).Offset", Method, 0, ""},
		{"(*File).Pos", Method, 0, ""},
		{"(*File).Position", Method, 0, ""},
		{"(*File).PositionFor", Method, 4, ""},
		{"(*File).SetLines", Method, 0, ""},
		{"(*File).SetLinesForContent", Method, 0, ""},
		{"(*File).Size", Method, 0, ""},
		{"(*FileSet).AddExistingFiles", Method, 25, ""},
		{"(*FileSet).AddFile", Method, 0, ""},
		{"(*FileSet).Base", Method, 0, ""},
		{"(*FileSet).File", Method, 0, ""},
		{"(*FileSet).Iterate", Method, 0, ""},
		{"(*FileSet).Position", Method, 0, ""},
		{"(*FileSet).PositionFor", Method, 4, ""},
		{"(*FileSet).Read", Method, 0, ""},
		{"(*FileSet).RemoveFile", Method, 20, ""},
		{"(*FileSet).Write", Method, 0, ""},
		{"(*Position).IsValid", Method, 0, ""},
		{"(Pos).IsValid", Method, 0, ""},
		{"(Position).String", Method, 0, ""},
		{"(Token).IsKeyword", Method, 0, ""},
		{"(Token).IsLiteral", Method, 0, ""},
		{"(Token).IsOperator", Method, 0, ""},
		{"(Token).Precedence", Method, 0, ""},
		{"(Token).String", Method, 0, ""},
		{"ADD", Const, 0, ""},
		{"ADD_ASSIGN", Const, 0, ""},
		{"AND", Const, 0, ""},
		{"AND_ASSIGN", Const, 0, ""},
		{"AND_NOT", Const, 0, ""},
		{"AND_NOT_ASSIGN", Const, 0, ""},
		{"ARROW", Const, 0, ""},
		{"ASSIGN", Const, 0, ""},
		{"BREAK", Const, 0, ""},
		{"CASE", Const, 0, ""},
		{"CHAN", Const, 0, ""},
		{"CHAR", Const, 0, ""},
		{"COLON", Const, 0, ""},
		{"COMMA", Const, 0, ""},
		{"COMMENT", Const, 0, ""},
		{"CONST", Const, 0, ""},
		{"CONTINUE", Const, 0, ""},
		{"DEC", Const, 0, ""},
		{"DEFAULT", Const, 0, ""},
		{"DEFER", Const, 0, ""},
		{"DEFINE", Const, 0, ""},
		{"ELLIPSIS", Const, 0, ""},
		{"ELSE", Const, 0, ""},
		{"EOF", Const, 0, ""},
		{"EQL", Const, 0, ""},
		{"FALLTHROUGH", Const, 0, ""},
		{"FLOAT", Const, 0, ""},
		{"FOR", Const, 0, ""},
		{"FUNC", Const, 0, ""},
		{"File", Type, 0, ""},
		{"FileSet", Type, 0, ""},
		{"GEQ", Const, 0, ""},
		{"GO", Const, 0, ""},
		{"GOTO", Const, 0, ""},
		{"GTR", Const, 0, ""},
		{"HighestPrec", Const, 0, ""},
		{"IDENT", Const, 0, ""},
		{"IF", Const, 0, ""},
		{"ILLEGAL", Const, 0, ""},
		{"IMAG", Const, 0, ""},
		{"IMPORT", Const, 0, ""},
		{"INC", Const, 0, ""},
		{"INT", Const, 0, ""},
		{"INTERFACE", Const, 0, ""},
		{"IsExported", Func, 13, "func(name string) bool"},
		{"IsIdentifier", Func, 13, "func(name string) bool"},
		{"IsKeyword", Func, 13, "func(name string) bool"},
		{"LAND", Const, 0, ""},
		{"LBRACE", Const, 0, ""},
		{"LBRACK", Const, 0, ""},
		{"LEQ", Const, 0, ""},
		{"LOR", Const, 0, ""},
		{"LPAREN", Const, 0, ""},
		{"LSS", Const, 0, ""},
		{"Lookup", Func, 0, "func(ident string) Token"},
		{"LowestPrec", Const, 0, ""},
		{"MAP", Const, 0, ""},
		{"MUL", Const, 0, ""},
		{"MUL_ASSIGN", Const, 0, ""},
		{"NEQ", Const, 0, ""},
		{"NOT", Const, 0, ""},
		{"NewFileSet", Func, 0, "func() *FileSet"},
		{"NoPos", Const, 0, ""},
		{"OR", Const, 0, ""},
		{"OR_ASSIGN", Const, 0, ""},
		{"PACKAGE", Const, 0, ""},
		{"PERIOD", Const, 0, ""},
		{"Pos", Type, 0, ""},
		{"Position", Type, 0, ""},
		{"Position.Column", Field, 0, ""},
		{"Position.Filename", Field, 0, ""},
		{"Position.Line", Field, 0, ""},
		{"Position.Offset", Field, 0, ""},
		{"QUO", Const, 0, ""},
		{"QUO_ASSIGN", Const, 0, ""},
		{"RANGE", Const, 0, ""},
		{"RBRACE", Const, 0, ""},
		{"RBRACK", Const, 0, ""},
		{"REM", Const, 0, ""},
		{"REM_ASSIGN", Const, 0, ""},
		{"RETURN", Const, 0, ""},
		{"RPAREN", Const, 0, ""},
		{"SELECT", Const, 0, ""},
		{"SEMICOLON", Const, 0, ""},
		{"SHL", Const, 0, ""},
		{"SHL_ASSIGN", Const, 0, ""},
		{"SHR", Const, 0, ""},
		{"SHR_ASSIGN", Const, 0, ""},
		{"STRING", Const, 0, ""},
		{"STRUCT", Const, 0, ""},
		{"SUB", Const, 0, ""},
		{"SUB_ASSIGN", Const, 0, ""},
		{"SWITCH", Const, 0, ""},
		{"TILDE", Const, 18, ""},
		{"TYPE", Const, 0, ""},
		{"Token", Type, 0, ""},
		{"UnaryPrec", Const, 0, ""},
		{"VAR", Const, 0, ""},
		{"XOR", Const, 0, ""},
		{"XOR_ASSIGN", Const, 0, ""},
	},
	"go/types": {
		{"(*Alias).Obj", Method, 22, ""},
		{"(*Alias).Origin", Method, 23, ""},
		{"(*Alias).Rhs", Method, 23, ""},
		{"(*Alias).SetTypeParams", Method, 23, ""},
		{"(*Alias).String", Method, 22, ""},
		{"(*Alias).TypeArgs", Method, 23, ""},
		{"(*Alias).TypeParams", Method, 23, ""},
		{"(*Alias).Underlying", Method, 22, ""},
		{"(*ArgumentError).Error", Method, 18, ""},
		{"(*ArgumentError).Unwrap", Method, 18, ""},
		{"(*Array).Elem", Method, 5, ""},
		{"(*Array).Len", Method, 5, ""},
		{"(*Array).String", Method, 5, ""},
		{"(*Array).Underlying", Method, 5, ""},
		{"(*Basic).Info", Method, 5, ""},
		{"(*Basic).Kind", Method, 5, ""},
		{"(*Basic).Name", Method, 5, ""},
		{"(*Basic).String", Method, 5, ""},
		{"(*Basic).Underlying", Method, 5, ""},
		{"(*Builtin).Exported", Method, 5, ""},
		{"(*Builtin).Id", Method, 5, ""},
		{"(*Builtin).Name", Method, 5, ""},
		{"(*Builtin).Parent", Method, 5, ""},
		{"(*Builtin).Pkg", Method, 5, ""},
		{"(*Builtin).Pos", Method, 5, ""},
		{"(*Builtin).String", Method, 5, ""},
		{"(*Builtin).Type", Method, 5, ""},
		{"(*Chan).Dir", Method, 5, ""},
		{"(*Chan).Elem", Method, 5, ""},
		{"(*Chan).String", Method, 5, ""},
		{"(*Chan).Underlying", Method, 5, ""},
		{"(*Checker).Files", Method, 5, ""},
		{"(*Config).Check", Method, 5, ""},
		{"(*Const).Exported", Method, 5, ""},
		{"(*Const).Id", Method, 5, ""},
		{"(*Const).Name", Method, 5, ""},
		{"(*Const).Parent", Method, 5, ""},
		{"(*Const).Pkg", Method, 5, ""},
		{"(*Const).Pos", Method, 5, ""},
		{"(*Const).String", Method, 5, ""},
		{"(*Const).Type", Method, 5, ""},
		{"(*Const).Val", Method, 5, ""},
		{"(*Func).Exported", Method, 5, ""},
		{"(*Func).FullName", Method, 5, ""},
		{"(*Func).Id", Method, 5, ""},
		{"(*Func).Name", Method, 5, ""},
		{"(*Func).Origin", Method, 19, ""},
		{"(*Func).Parent", Method, 5, ""},
		{"(*Func).Pkg", Method, 5, ""},
		{"(*Func).Pos", Method, 5, ""},
		{"(*Func).Scope", Method, 5, ""},
		{"(*Func).Signature", Method, 23, ""},
		{"(*Func).String", Method, 5, ""},
		{"(*Func).Type", Method, 5, ""},
		{"(*Info).ObjectOf", Method, 5, ""},
		{"(*Info).PkgNameOf", Method, 22, ""},
		{"(*Info).TypeOf", Method, 5, ""},
		{"(*Initializer).String", Method, 5, ""},
		{"(*Interface).Complete", Method, 5, ""},
		{"(*Interface).Embedded", Method, 5, ""},
		{"(*Interface).EmbeddedType", Method, 11, ""},
		{"(*Interface).EmbeddedTypes", Method, 24, ""},
		{"(*Interface).Empty", Method, 5, ""},
		{"(*Interface).ExplicitMethod", Method, 5, ""},
		{"(*Interface).ExplicitMethods", Method, 24, ""},
		{"(*Interface).IsComparable", Method, 18, ""},
		{"(*Interface).IsImplicit", Method, 18, ""},
		{"(*Interface).IsMethodSet", Method, 18, ""},
		{"(*Interface).MarkImplicit", Method, 18, ""},
		{"(*Interface).Method", Method, 5, ""},
		{"(*Interface).Methods", Method, 24, ""},
		{"(*Interface).NumEmbeddeds", Method, 5, ""},
		{"(*Interface).NumExplicitMethods", Method, 5, ""},
		{"(*Interface).NumMethods", Method, 5, ""},
		{"(*Interface).String", Method, 5, ""},
		{"(*Interface).Underlying", Method, 5, ""},
		{"(*Label).Exported", Method, 5, ""},
		{"(*Label).Id", Method, 5, ""},
		{"(*Label).Name", Method, 5, ""},
		{"(*Label).Parent", Method, 5, ""},
		{"(*Label).Pkg", Method, 5, ""},
		{"(*Label).Pos", Method, 5, ""},
		{"(*Label).String", Method, 5, ""},
		{"(*Label).Type", Method, 5, ""},
		{"(*Map).Elem", Method, 5, ""},
		{"(*Map).Key", Method, 5, ""},
		{"(*Map).String", Method, 5, ""},
		{"(*Map).Underlying", Method, 5, ""},
		{"(*MethodSet).At", Method, 5, ""},
		{"(*MethodSet).Len", Method, 5, ""},
		{"(*MethodSet).Lookup", Method, 5, ""},
		{"(*MethodSet).Methods", Method, 24, ""},
		{"(*MethodSet).String", Method, 5, ""},
		{"(*Named).AddMethod", Method, 5, ""},
		{"(*Named).Method", Method, 5, ""},
		{"(*Named).Methods", Method, 24, ""},
		{"(*Named).NumMethods", Method, 5, ""},
		{"(*Named).Obj", Method, 5, ""},
		{"(*Named).Origin", Method, 18, ""},
		{"(*Named).SetTypeParams", Method, 18, ""},
		{"(*Named).SetUnderlying", Method, 5, ""},
		{"(*Named).String", Method, 5, ""},
		{"(*Named).TypeArgs", Method, 18, ""},
		{"(*Named).TypeParams", Method, 18, ""},
		{"(*Named).Underlying", Method, 5, ""},
		{"(*Nil).Exported", Method, 5, ""},
		{"(*Nil).Id", Method, 5, ""},
		{"(*Nil).Name", Method, 5, ""},
		{"(*Nil).Parent", Method, 5, ""},
		{"(*Nil).Pkg", Method, 5, ""},
		{"(*Nil).Pos", Method, 5, ""},
		{"(*Nil).String", Method, 5, ""},
		{"(*Nil).Type", Method, 5, ""},
		{"(*Package).Complete", Method, 5, ""},
		{"(*Package).GoVersion", Method, 21, ""},
		{"(*Package).Imports", Method, 5, ""},
		{"(*Package).MarkComplete", Method, 5, ""},
		{"(*Package).Name", Method, 5, ""},
		{"(*Package).Path", Method, 5, ""},
		{"(*Package).Scope", Method, 5, ""},
		{"(*Package).SetImports", Method, 5, ""},
		{"(*Package).SetName", Method, 6, ""},
		{"(*Package).String", Method, 5, ""},
		{"(*PkgName).Exported", Method, 5, ""},
		{"(*PkgName).Id", Method, 5, ""},
		{"(*PkgName).Imported", Method, 5, ""},
		{"(*PkgName).Name", Method, 5, ""},
		{"(*PkgName).Parent", Method, 5, ""},
		{"(*PkgName).Pkg", Method, 5, ""},
		{"(*PkgName).Pos", Method, 5, ""},
		{"(*PkgName).String", Method, 5, ""},
		{"(*PkgName).Type", Method, 5, ""},
		{"(*Pointer).Elem", Method, 5, ""},
		{"(*Pointer).String", Method, 5, ""},
		{"(*Pointer).Underlying", Method, 5, ""},
		{"(*Scope).Child", Method, 5, ""},
		{"(*Scope).Children", Method, 24, ""},
		{"(*Scope).Contains", Method, 5, ""},
		{"(*Scope).End", Method, 5, ""},
		{"(*Scope).Innermost", Method, 5, ""},
		{"(*Scope).Insert", Method, 5, ""},
		{"(*Scope).Len", Method, 5, ""},
		{"(*Scope).Lookup", Method, 5, ""},
		{"(*Scope).LookupParent", Method, 5, ""},
		{"(*Scope).Names", Method, 5, ""},
		{"(*Scope).NumChildren", Method, 5, ""},
		{"(*Scope).Parent", Method, 5, ""},
		{"(*Scope).Pos", Method, 5, ""},
		{"(*Scope).String", Method, 5, ""},
		{"(*Scope).WriteTo", Method, 5, ""},
		{"(*Selection).Index", Method, 5, ""},
		{"(*Selection).Indirect", Method, 5, ""},
		{"(*Selection).Kind", Method, 5, ""},
		{"(*Selection).Obj", Method, 5, ""},
		{"(*Selection).Recv", Method, 5, ""},
		{"(*Selection).String", Method, 5, ""},
		{"(*Selection).Type", Method, 5, ""},
		{"(*Signature).Params", Method, 5, ""},
		{"(*Signature).Recv", Method, 5, ""},
		{"(*Signature).RecvTypeParams", Method, 18, ""},
		{"(*Signature).Results", Method, 5, ""},
		{"(*Signature).String", Method, 5, ""},
		{"(*Signature).TypeParams", Method, 18, ""},
		{"(*Signature).Underlying", Method, 5, ""},
		{"(*Signature).Variadic", Method, 5, ""},
		{"(*Slice).Elem", Method, 5, ""},
		{"(*Slice).String", Method, 5, ""},
		{"(*Slice).Underlying", Method, 5, ""},
		{"(*StdSizes).Alignof", Method, 5, ""},
		{"(*StdSizes).Offsetsof", Method, 5, ""},
		{"(*StdSizes).Sizeof", Method, 5, ""},
		{"(*Struct).Field", Method, 5, ""},
		{"(*Struct).Fields", Method, 24, ""},
		{"(*Struct).NumFields", Method, 5, ""},
		{"(*Struct).String", Method, 5, ""},
		{"(*Struct).Tag", Method, 5, ""},
		{"(*Struct).Underlying", Method, 5, ""},
		{"(*Term).String", Method, 18, ""},
		{"(*Term).Tilde", Method, 18, ""},
		{"(*Term).Type", Method, 18, ""},
		{"(*Tuple).At", Method, 5, ""},
		{"(*Tuple).Len", Method, 5, ""},
		{"(*Tuple).String", Method, 5, ""},
		{"(*Tuple).Underlying", Method, 5, ""},
		{"(*Tuple).Variables", Method, 24, ""},
		{"(*TypeList).At", Method, 18, ""},
		{"(*TypeList).Len", Method, 18, ""},
		{"(*TypeList).Types", Method, 24, ""},
		{"(*TypeName).Exported", Method, 5, ""},
		{"(*TypeName).Id", Method, 5, ""},
		{"(*TypeName).IsAlias", Method, 9, ""},
		{"(*TypeName).Name", Method, 5, ""},
		{"(*TypeName).Parent", Method, 5, ""},
		{"(*TypeName).Pkg", Method, 5, ""},
		{"(*TypeName).Pos", Method, 5, ""},
		{"(*TypeName).String", Method, 5, ""},
		{"(*TypeName).Type", Method, 5, ""},
		{"(*TypeParam).Constraint", Method, 18, ""},
		{"(*TypeParam).Index", Method, 18, ""},
		{"(*TypeParam).Obj", Method, 18, ""},
		{"(*TypeParam).SetConstraint", Method, 18, ""},
		{"(*TypeParam).String", Method, 18, ""},
		{"(*TypeParam).Underlying", Method, 18, ""},
		{"(*TypeParamList).At", Method, 18, ""},
		{"(*TypeParamList).Len", Method, 18, ""},
		{"(*TypeParamList).TypeParams", Method, 24, ""},
		{"(*Union).Len", Method, 18, ""},
		{"(*Union).String", Method, 18, ""},
		{"(*Union).Term", Method, 18, ""},
		{"(*Union).Terms", Method, 24, ""},
		{"(*Union).Underlying", Method, 18, ""},
		{"(*Var).Anonymous", Method, 5, ""},
		{"(*Var).Embedded", Method, 11, ""},
		{"(*Var).Exported", Method, 5, ""},
		{"(*Var).Id", Method, 5, ""},
		{"(*Var).IsField", Method, 5, ""},
		{"(*Var).Kind", Method, 25, ""},
		{"(*Var).Name", Method, 5, ""},
		{"(*Var).Origin", Method, 19, ""},
		{"(*Var).Parent", Method, 5, ""},
		{"(*Var).Pkg", Method, 5, ""},
		{"(*Var).Pos", Method, 5, ""},
		{"(*Var).SetKind", Method, 25, ""},
		{"(*Var).String", Method, 5, ""},
		{"(*Var).Type", Method, 5, ""},
		{"(Checker).ObjectOf", Method, 5, ""},
		{"(Checker).PkgNameOf", Method, 22, ""},
		{"(Checker).TypeOf", Method, 5, ""},
		{"(Error).Error", Method, 5, ""},
		{"(Importer).Import", Method, 5, ""},
		{"(ImporterFrom).Import", Method, 6, ""},
		{"(ImporterFrom).ImportFrom", Method, 6, ""},
		{"(Object).Exported", Method, 5, ""},
		{"(Object).Id", Method, 5, ""},
		{"(Object).Name", Method, 5, ""},
		{"(Object).Parent", Method, 5, ""},
		{"(Object).Pkg", Method, 5, ""},
		{"(Object).Pos", Method, 5, ""},
		{"(Object).String", Method, 5, ""},
		{"(Object).Type", Method, 5, ""},
		{"(Sizes).Alignof", Method, 5, ""},
		{"(Sizes).Offsetsof", Method, 5, ""},
		{"(Sizes).Sizeof", Method, 5, ""},
		{"(Type).String", Method, 5, ""},
		{"(Type).Underlying", Method, 5, ""},
		{"(TypeAndValue).Addressable", Method, 5, ""},
		{"(TypeAndValue).Assignable", Method, 5, ""},
		{"(TypeAndValue).HasOk", Method, 5, ""},
		{"(TypeAndValue).IsBuiltin", Method, 5, ""},
		{"(TypeAndValue).IsNil", Method, 5, ""},
		{"(TypeAndValue).IsType", Method, 5, ""},
		{"(TypeAndValue).IsValue", Method, 5, ""},
		{"(TypeAndValue).IsVoid", Method, 5, ""},
		{"(VarKind).String", Method, 25, ""},
		{"Alias", Type, 22, ""},
		{"ArgumentError", Type, 18, ""},
		{"ArgumentError.Err", Field, 18, ""},
		{"ArgumentError.Index", Field, 18, ""},
		{"Array", Type, 5, ""},
		{"AssertableTo", Func, 5, "func(V *Interface, T Type) bool"},
		{"AssignableTo", Func, 5, "func(V Type, T Type) bool"},
		{"Basic", Type, 5, ""},
		{"BasicInfo", Type, 5, ""},
		{"BasicKind", Type, 5, ""},
		{"Bool", Const, 5, ""},
		{"Builtin", Type, 5, ""},
		{"Byte", Const, 5, ""},
		{"Chan", Type, 5, ""},
		{"ChanDir", Type, 5, ""},
		{"CheckExpr", Func, 13, "func(fset *token.FileSet, pkg *Package, pos token.Pos, expr ast.Expr, info *Info) (err error)"},
		{"Checker", Type, 5, ""},
		{"Checker.Info", Field, 5, ""},
		{"Comparable", Func, 5, "func(T Type) bool"},
		{"Complex128", Const, 5, ""},
		{"Complex64", Const, 5, ""},
		{"Config", Type, 5, ""},
		{"Config.Context", Field, 18, ""},
		{"Config.DisableUnusedImportCheck", Field, 5, ""},
		{"Config.Error", Field, 5, ""},
		{"Config.FakeImportC", Field, 5, ""},
		{"Config.GoVersion", Field, 18, ""},
		{"Config.IgnoreFuncBodies", Field, 5, ""},
		{"Config.Importer", Field, 5, ""},
		{"Config.Sizes", Field, 5, ""},
		{"Const", Type, 5, ""},
		{"Context", Type, 18, ""},
		{"ConvertibleTo", Func, 5, "func(V Type, T Type) bool"},
		{"DefPredeclaredTestFuncs", Func, 5, "func()"},
		{"Default", Func, 8, "func(t Type) Type"},
		{"Error", Type, 5, ""},
		{"Error.Fset", Field, 5, ""},
		{"Error.Msg", Field, 5, ""},
		{"Error.Pos", Field, 5, ""},
		{"Error.Soft", Field, 5, ""},
		{"Eval", Func, 5, "func(fset *token.FileSet, pkg *Package, pos token.Pos, expr string) (_ TypeAndValue, err error)"},
		{"ExprString", Func, 5, "func(x ast.Expr) string"},
		{"FieldVal", Const, 5, ""},
		{"FieldVar", Const, 25, ""},
		{"Float32", Const, 5, ""},
		{"Float64", Const, 5, ""},
		{"Func", Type, 5, ""},
		{"Id", Func, 5, "func(pkg *Package, name string) string"},
		{"Identical", Func, 5, "func(x Type, y Type) bool"},
		{"IdenticalIgnoreTags", Func, 8, "func(x Type, y Type) bool"},
		{"Implements", Func, 5, "func(V Type, T *Interface) bool"},
		{"ImportMode", Type, 6, ""},
		{"Importer", Type, 5, ""},
		{"ImporterFrom", Type, 6, ""},
		{"Info", Type, 5, ""},
		{"Info.Defs", Field, 5, ""},
		{"Info.FileVersions", Field, 22, ""},
		{"Info.Implicits", Field, 5, ""},
		{"Info.InitOrder", Field, 5, ""},
		{"Info.Instances", Field, 18, ""},
		{"Info.Scopes", Field, 5, ""},
		{"Info.Selections", Field, 5, ""},
		{"Info.Types", Field, 5, ""},
		{"Info.Uses", Field, 5, ""},
		{"Initializer", Type, 5, ""},
		{"Initializer.Lhs", Field, 5, ""},
		{"Initializer.Rhs", Field, 5, ""},
		{"Instance", Type, 18, ""},
		{"Instance.Type", Field, 18, ""},
		{"Instance.TypeArgs", Field, 18, ""},
		{"Instantiate", Func, 18, "func(ctxt *Context, orig Type, targs []Type, validate bool) (Type, error)"},
		{"Int", Const, 5, ""},
		{"Int16", Const, 5, ""},
		{"Int32", Const, 5, ""},
		{"Int64", Const, 5, ""},
		{"Int8", Const, 5, ""},
		{"Interface", Type, 5, ""},
		{"Invalid", Const, 5, ""},
		{"IsBoolean", Const, 5, ""},
		{"IsComplex", Const, 5, ""},
		{"IsConstType", Const, 5, ""},
		{"IsFloat", Const, 5, ""},
		{"IsInteger", Const, 5, ""},
		{"IsInterface", Func, 5, "func(t Type) bool"},
		{"IsNumeric", Const, 5, ""},
		{"IsOrdered", Const, 5, ""},
		{"IsString", Const, 5, ""},
		{"IsUnsigned", Const, 5, ""},
		{"IsUntyped", Const, 5, ""},
		{"Label", Type, 5, ""},
		{"LocalVar", Const, 25, ""},
		{"LookupFieldOrMethod", Func, 5, "func(T Type, addressable bool, pkg *Package, name string) (obj Object, index []int, indirect bool)"},
		{"LookupSelection", Func, 25, "func(T Type, addressable bool, pkg *Package, name string) (Selection, bool)"},
		{"Map", Type, 5, ""},
		{"MethodExpr", Const, 5, ""},
		{"MethodSet", Type, 5, ""},
		{"MethodVal", Const, 5, ""},
		{"MissingMethod", Func, 5, "func(V Type, T *Interface, static bool) (method *Func, wrongType bool)"},
		{"Named", Type, 5, ""},
		{"NewAlias", Func, 22, "func(obj *TypeName, rhs Type) *Alias"},
		{"NewArray", Func, 5, "func(elem Type, len int64) *Array"},
		{"NewChan", Func, 5, "func(dir ChanDir, elem Type) *Chan"},
		{"NewChecker", Func, 5, "func(conf *Config, fset *token.FileSet, pkg *Package, info *Info) *Checker"},
		{"NewConst", Func, 5, "func(pos token.Pos, pkg *Package, name string, typ Type, val constant.Value) *Const"},
		{"NewContext", Func, 18, "func() *Context"},
		{"NewField", Func, 5, "func(pos token.Pos, pkg *Package, name string, typ Type, embedded bool) *Var"},
		{"NewFunc", Func, 5, "func(pos token.Pos, pkg *Package, name string, sig *Signature) *Func"},
		{"NewInterface", Func, 5, "func(methods []*Func, embeddeds []*Named) *Interface"},
		{"NewInterfaceType", Func, 11, "func(methods []*Func, embeddeds []Type) *Interface"},
		{"NewLabel", Func, 5, "func(pos token.Pos, pkg *Package, name string) *Label"},
		{"NewMap", Func, 5, "func(key Type, elem Type) *Map"},
		{"NewMethodSet", Func, 5, "func(T Type) *MethodSet"},
		{"NewNamed", Func, 5, "func(obj *TypeName, underlying Type, methods []*Func) *Named"},
		{"NewPackage", Func, 5, "func(path string, name string) *Package"},
		{"NewParam", Func, 5, "func(pos token.Pos, pkg *Package, name string, typ Type) *Var"},
		{"NewPkgName", Func, 5, "func(pos token.Pos, pkg *Package, name string, imported *Package) *PkgName"},
		{"NewPointer", Func, 5, "func(elem Type) *Pointer"},
		{"NewScope", Func, 5, "func(parent *Scope, pos token.Pos, end token.Pos, comment string) *Scope"},
		{"NewSignature", Func, 5, "func(recv *Var, params *Tuple, results *Tuple, variadic bool) *Signature"},
		{"NewSignatureType", Func, 18, "func(recv *Var, recvTypeParams []*TypeParam, typeParams []*TypeParam, params *Tuple, results *Tuple, variadic bool) *Signature"},
		{"NewSlice", Func, 5, "func(elem Type) *Slice"},
		{"NewStruct", Func, 5, "func(fields []*Var, tags []string) *Struct"},
		{"NewTerm", Func, 18, "func(tilde bool, typ Type) *Term"},
		{"NewTuple", Func, 5, "func(x ...*Var) *Tuple"},
		{"NewTypeName", Func, 5, "func(pos token.Pos, pkg *Package, name string, typ Type) *TypeName"},
		{"NewTypeParam", Func, 18, "func(obj *TypeName, constraint Type) *TypeParam"},
		{"NewUnion", Func, 18, "func(terms []*Term) *Union"},
		{"NewVar", Func, 5, "func(pos token.Pos, pkg *Package, name string, typ Type) *Var"},
		{"Nil", Type, 5, ""},
		{"ObjectString", Func, 5, "func(obj Object, qf Qualifier) string"},
		{"Package", Type, 5, ""},
		{"PackageVar", Const, 25, ""},
		{"ParamVar", Const, 25, ""},
		{"PkgName", Type, 5, ""},
		{"Pointer", Type, 5, ""},
		{"Qualifier", Type, 5, ""},
		{"RecvOnly", Const, 5, ""},
		{"RecvVar", Const, 25, ""},
		{"RelativeTo", Func, 5, "func(pkg *Package) Qualifier"},
		{"ResultVar", Const, 25, ""},
		{"Rune", Const, 5, ""},
		{"Satisfies", Func, 20, "func(V Type, T *Interface) bool"},
		{"Scope", Type, 5, ""},
		{"Selection", Type, 5, ""},
		{"SelectionKind", Type, 5, ""},
		{"SelectionString", Func, 5, "func(s *Selection, qf Qualifier) string"},
		{"SendOnly", Const, 5, ""},
		{"SendRecv", Const, 5, ""},
		{"Signature", Type, 5, ""},
		{"Sizes", Type, 5, ""},
		{"SizesFor", Func, 9, "func(compiler string, arch string) Sizes"},
		{"Slice", Type, 5, ""},
		{"StdSizes", Type, 5, ""},
		{"StdSizes.MaxAlign", Field, 5, ""},
		{"StdSizes.WordSize", Field, 5, ""},
		{"String", Const, 5, ""},
		{"Struct", Type, 5, ""},
		{"Term", Type, 18, ""},
		{"Tuple", Type, 5, ""},
		{"Typ", Var, 5, ""},
		{"Type", Type, 5, ""},
		{"TypeAndValue", Type, 5, ""},
		{"TypeAndValue.Type", Field, 5, ""},
		{"TypeAndValue.Value", Field, 5, ""},
		{"TypeList", Type, 18, ""},
		{"TypeName", Type, 5, ""},
		{"TypeParam", Type, 18, ""},
		{"TypeParamList", Type, 18, ""},
		{"TypeString", Func, 5, "func(typ Type, qf Qualifier) string"},
		{"Uint", Const, 5, ""},
		{"Uint16", Const, 5, ""},
		{"Uint32", Const, 5, ""},
		{"Uint64", Const, 5, ""},
		{"Uint8", Const, 5, ""},
		{"Uintptr", Const, 5, ""},
		{"Unalias", Func, 22, "func(t Type) Type"},
		{"Union", Type, 18, ""},
		{"Universe", Var, 5, ""},
		{"Unsafe", Var, 5, ""},
		{"UnsafePointer", Const, 5, ""},
		{"UntypedBool", Const, 5, ""},
		{"UntypedComplex", Const, 5, ""},
		{"UntypedFloat", Const, 5, ""},
		{"UntypedInt", Const, 5, ""},
		{"UntypedNil", Const, 5, ""},
		{"UntypedRune", Const, 5, ""},
		{"UntypedString", Const, 5, ""},
		{"Var", Type, 5, ""},
		{"VarKind", Type, 25, ""},
		{"WriteExpr", Func, 5, "func(buf *bytes.Buffer, x ast.Expr)"},
		{"WriteSignature", Func, 5, "func(buf *bytes.Buffer, sig *Signature, qf Qualifier)"},
		{"WriteType", Func, 5, "func(buf *bytes.Buffer, typ Type, qf Qualifier)"},
	},
	"go/version": {
		{"Compare", Func, 22, "func(x string, y string) int"},
		{"IsValid", Func, 22, "func(x string) bool"},
		{"Lang", Func, 22, "func(x string) string"},
	},
	"hash": {
		{"(Cloner).BlockSize", Method, 25, ""},
		{"(Cloner).Clone", Method, 25, ""},
		{"(Cloner).Reset", Method, 25, ""},
		{"(Cloner).Size", Method, 25, ""},
		{"(Cloner).Sum", Method, 25, ""},
		{"(Cloner).Write", Method, 25, ""},
		{"(Hash).BlockSize", Method, 0, ""},
		{"(Hash).Reset", Method, 0, ""},
		{"(Hash).Size", Method, 0, ""},
		{"(Hash).Sum", Method, 0, ""},
		{"(Hash).Write", Method, 0, ""},
		{"(Hash32).BlockSize", Method, 0, ""},
		{"(Hash32).Reset", Method, 0, ""},
		{"(Hash32).Size", Method, 0, ""},
		{"(Hash32).Sum", Method, 0, ""},
		{"(Hash32).Sum32", Method, 0, ""},
		{"(Hash32).Write", Method, 0, ""},
		{"(Hash64).BlockSize", Method, 0, ""},
		{"(Hash64).Reset", Method, 0, ""},
		{"(Hash64).Size", Method, 0, ""},
		{"(Hash64).Sum", Method, 0, ""},
		{"(Hash64).Sum64", Method, 0, ""},
		{"(Hash64).Write", Method, 0, ""},
		{"(XOF).BlockSize", Method, 25, ""},
		{"(XOF).Read", Method, 25, ""},
		{"(XOF).Reset", Method, 25, ""},
		{"(XOF).Write", Method, 25, ""},
		{"Cloner", Type, 25, ""},
		{"Hash", Type, 0, ""},
		{"Hash32", Type, 0, ""},
		{"Hash64", Type, 0, ""},
		{"XOF", Type, 25, ""},
	},
	"hash/adler32": {
		{"Checksum", Func, 0, "func(data []byte) uint32"},
		{"New", Func, 0, "func() hash.Hash32"},
		{"Size", Const, 0, ""},
	},
	"hash/crc32": {
		{"Castagnoli", Const, 0, ""},
		{"Checksum", Func, 0, "func(data []byte, tab *Table) uint32"},
		{"ChecksumIEEE", Func, 0, "func(data []byte) uint32"},
		{"IEEE", Const, 0, ""},
		{"IEEETable", Var, 0, ""},
		{"Koopman", Const, 0, ""},
		{"MakeTable", Func, 0, "func(poly uint32) *Table"},
		{"New", Func, 0, "func(tab *Table) hash.Hash32"},
		{"NewIEEE", Func, 0, "func() hash.Hash32"},
		{"Size", Const, 0, ""},
		{"Table", Type, 0, ""},
		{"Update", Func, 0, "func(crc uint32, tab *Table, p []byte) uint32"},
	},
	"hash/crc64": {
		{"Checksum", Func, 0, "func(data []byte, tab *Table) uint64"},
		{"ECMA", Const, 0, ""},
		{"ISO", Const, 0, ""},
		{"MakeTable", Func, 0, "func(poly uint64) *Table"},
		{"New", Func, 0, "func(tab *Table) hash.Hash64"},
		{"Size", Const, 0, ""},
		{"Table", Type, 0, ""},
		{"Update", Func, 0, "func(crc uint64, tab *Table, p []byte) uint64"},
	},
	"hash/fnv": {
		{"New128", Func, 9, "func() hash.Hash"},
		{"New128a", Func, 9, "func() hash.Hash"},
		{"New32", Func, 0, "func() hash.Hash32"},
		{"New32a", Func, 0, "func() hash.Hash32"},
		{"New64", Func, 0, "func() hash.Hash64"},
		{"New64a", Func, 0, "func() hash.Hash64"},
	},
	"hash/maphash": {
		{"(*Hash).BlockSize", Method, 14, ""},
		{"(*Hash).Clone", Method, 25, ""},
		{"(*Hash).Reset", Method, 14, ""},
		{"(*Hash).Seed", Method, 14, ""},
		{"(*Hash).SetSeed", Method, 14, ""},
		{"(*Hash).Size", Method, 14, ""},
		{"(*Hash).Sum", Method, 14, ""},
		{"(*Hash).Sum64", Method, 14, ""},
		{"(*Hash).Write", Method, 14, ""},
		{"(*Hash).WriteByte", Method, 14, ""},
		{"(*Hash).WriteString", Method, 14, ""},
		{"Bytes", Func, 19, "func(seed Seed, b []byte) uint64"},
		{"Comparable", Func, 24, "func[T comparable](seed Seed, v T) uint64"},
		{"Hash", Type, 14, ""},
		{"MakeSeed", Func, 14, "func() Seed"},
		{"Seed", Type, 14, ""},
		{"String", Func, 19, "func(seed Seed, s string) uint64"},
		{"WriteComparable", Func, 24, "func[T comparable](h *Hash, x T)"},
	},
	"html": {
		{"EscapeString", Func, 0, "func(s string) string"},
		{"UnescapeString", Func, 0, "func(s string) string"},
	},
	"html/template": {
		{"(*Error).Error", Method, 0, ""},
		{"(*Template).AddParseTree", Method, 0, ""},
		{"(*Template).Clone", Method, 0, ""},
		{"(*Template).DefinedTemplates", Method, 6, ""},
		{"(*Template).Delims", Method, 0, ""},
		{"(*Template).Execute", Method, 0, ""},
		{"(*Template).ExecuteTemplate", Method, 0, ""},
		{"(*Template).Funcs", Method, 0, ""},
		{"(*Template).Lookup", Method, 0, ""},
		{"(*Template).Name", Method, 0, ""},
		{"(*Template).New", Method, 0, ""},
		{"(*Template).Option", Method, 5, ""},
		{"(*Template).Parse", Method, 0, ""},
		{"(*Template).ParseFS", Method, 16, ""},
		{"(*Template).ParseFiles", Method, 0, ""},
		{"(*Template).ParseGlob", Method, 0, ""},
		{"(*Template).Templates", Method, 0, ""},
		{"CSS", Type, 0, ""},
		{"ErrAmbigContext", Const, 0, ""},
		{"ErrBadHTML", Const, 0, ""},
		{"ErrBranchEnd", Const, 0, ""},
		{"ErrEndContext", Const, 0, ""},
		{"ErrJSTemplate", Const, 21, ""},
		{"ErrNoSuchTemplate", Const, 0, ""},
		{"ErrOutputContext", Const, 0, ""},
		{"ErrPartialCharset", Const, 0, ""},
		{"ErrPartialEscape", Const, 0, ""},
		{"ErrPredefinedEscaper", Const, 9, ""},
		{"ErrRangeLoopReentry", Const, 0, ""},
		{"ErrSlashAmbig", Const, 0, ""},
		{"Error", Type, 0, ""},
		{"Error.Description", Field, 0, ""},
		{"Error.ErrorCode", Field, 0, ""},
		{"Error.Line", Field, 0, ""},
		{"Error.Name", Field, 0, ""},
		{"Error.Node", Field, 4, ""},
		{"ErrorCode", Type, 0, ""},
		{"FuncMap", Type, 0, ""},
		{"HTML", Type, 0, ""},
		{"HTMLAttr", Type, 0, ""},
		{"HTMLEscape", Func, 0, "func(w io.Writer, b []byte)"},
		{"HTMLEscapeString", Func, 0, "func(s string) string"},
		{"HTMLEscaper", Func, 0, "func(args ...any) string"},
		{"IsTrue", Func, 6, "func(val any) (truth bool, ok bool)"},
		{"JS", Type, 0, ""},
		{"JSEscape", Func, 0, "func(w io.Writer, b []byte)"},
		{"JSEscapeString", Func, 0, "func(s string) string"},
		{"JSEscaper", Func, 0, "func(args ...any) string"},
		{"JSStr", Type, 0, ""},
		{"Must", Func, 0, "func(t *Template, err error) *Template"},
		{"New", Func, 0, "func(name string) *Template"},
		{"OK", Const, 0, ""},
		{"ParseFS", Func, 16, "func(fs fs.FS, patterns ...string) (*Template, error)"},
		{"ParseFiles", Func, 0, "func(filenames ...string) (*Template, error)"},
		{"ParseGlob", Func, 0, "func(pattern string) (*Template, error)"},
		{"Srcset", Type, 10, ""},
		{"Template", Type, 0, ""},
		{"Template.Tree", Field, 2, ""},
		{"URL", Type, 0, ""},
		{"URLQueryEscaper", Func, 0, "func(args ...any) string"},
	},
	"image": {
		{"(*Alpha).AlphaAt", Method, 4, ""},
		{"(*Alpha).At", Method, 0, ""},
		{"(*Alpha).Bounds", Method, 0, ""},
		{"(*Alpha).ColorModel", Method, 0, ""},
		{"(*Alpha).Opaque", Method, 0, ""},
		{"(*Alpha).PixOffset", Method, 0, ""},
		{"(*Alpha).RGBA64At", Method, 17, ""},
		{"(*Alpha).Set", Method, 0, ""},
		{"(*Alpha).SetAlpha", Method, 0, ""},
		{"(*Alpha).SetRGBA64", Method, 17, ""},
		{"(*Alpha).SubImage", Method, 0, ""},
		{"(*Alpha16).Alpha16At", Method, 4, ""},
		{"(*Alpha16).At", Method, 0, ""},
		{"(*Alpha16).Bounds", Method, 0, ""},
		{"(*Alpha16).ColorModel", Method, 0, ""},
		{"(*Alpha16).Opaque", Method, 0, ""},
		{"(*Alpha16).PixOffset", Method, 0, ""},
		{"(*Alpha16).RGBA64At", Method, 17, ""},
		{"(*Alpha16).Set", Method, 0, ""},
		{"(*Alpha16).SetAlpha16", Method, 0, ""},
		{"(*Alpha16).SetRGBA64", Method, 17, ""},
		{"(*Alpha16).SubImage", Method, 0, ""},
		{"(*CMYK).At", Method, 5, ""},
		{"(*CMYK).Bounds", Method, 5, ""},
		{"(*CMYK).CMYKAt", Method, 5, ""},
		{"(*CMYK).ColorModel", Method, 5, ""},
		{"(*CMYK).Opaque", Method, 5, ""},
		{"(*CMYK).PixOffset", Method, 5, ""},
		{"(*CMYK).RGBA64At", Method, 17, ""},
		{"(*CMYK).Set", Method, 5, ""},
		{"(*CMYK).SetCMYK", Method, 5, ""},
		{"(*CMYK).SetRGBA64", Method, 17, ""},
		{"(*CMYK).SubImage", Method, 5, ""},
		{"(*Gray).At", Method, 0, ""},
		{"(*Gray).Bounds", Method, 0, ""},
		{"(*Gray).ColorModel", Method, 0, ""},
		{"(*Gray).GrayAt", Method, 4, ""},
		{"(*Gray).Opaque", Method, 0, ""},
		{"(*Gray).PixOffset", Method, 0, ""},
		{"(*Gray).RGBA64At", Method, 17, ""},
		{"(*Gray).Set", Method, 0, ""},
		{"(*Gray).SetGray", Method, 0, ""},
		{"(*Gray).SetRGBA64", Method, 17, ""},
		{"(*Gray).SubImage", Method, 0, ""},
		{"(*Gray16).At", Method, 0, ""},
		{"(*Gray16).Bounds", Method, 0, ""},
		{"(*Gray16).ColorModel", Method, 0, ""},
		{"(*Gray16).Gray16At", Method, 4, ""},
		{"(*Gray16).Opaque", Method, 0, ""},
		{"(*Gray16).PixOffset", Method, 0, ""},
		{"(*Gray16).RGBA64At", Method, 17, ""},
		{"(*Gray16).Set", Method, 0, ""},
		{"(*Gray16).SetGray16", Method, 0, ""},
		{"(*Gray16).SetRGBA64", Method, 17, ""},
		{"(*Gray16).SubImage", Method, 0, ""},
		{"(*NRGBA).At", Method, 0, ""},
		{"(*NRGBA).Bounds", Method, 0, ""},
		{"(*NRGBA).ColorModel", Method, 0, ""},
		{"(*NRGBA).NRGBAAt", Method, 4, ""},
		{"(*NRGBA).Opaque", Method, 0, ""},
		{"(*NRGBA).PixOffset", Method, 0, ""},
		{"(*NRGBA).RGBA64At", Method, 17, ""},
		{"(*NRGBA).Set", Method, 0, ""},
		{"(*NRGBA).SetNRGBA", Method, 0, ""},
		{"(*NRGBA).SetRGBA64", Method, 17, ""},
		{"(*NRGBA).SubImage", Method, 0, ""},
		{"(*NRGBA64).At", Method, 0, ""},
		{"(*NRGBA64).Bounds", Method, 0, ""},
		{"(*NRGBA64).ColorModel", Method, 0, ""},
		{"(*NRGBA64).NRGBA64At", Method, 4, ""},
		{"(*NRGBA64).Opaque", Method, 0, ""},
		{"(*NRGBA64).PixOffset", Method, 0, ""},
		{"(*NRGBA64).RGBA64At", Method, 17, ""},
		{"(*NRGBA64).Set", Method, 0, ""},
		{"(*NRGBA64).SetNRGBA64", Method, 0, ""},
		{"(*NRGBA64).SetRGBA64", Method, 17, ""},
		{"(*NRGBA64).SubImage", Method, 0, ""},
		{"(*NYCbCrA).AOffset", Method, 6, ""},
		{"(*NYCbCrA).At", Method, 6, ""},
		{"(*NYCbCrA).Bounds", Method, 6, ""},
		{"(*NYCbCrA).COffset", Method, 6, ""},
		{"(*NYCbCrA).ColorModel", Method, 6, ""},
		{"(*NYCbCrA).NYCbCrAAt", Method, 6, ""},
		{"(*NYCbCrA).Opaque", Method, 6, ""},
		{"(*NYCbCrA).RGBA64At", Method, 17, ""},
		{"(*NYCbCrA).SubImage", Method, 6, ""},
		{"(*NYCbCrA).YCbCrAt", Method, 6, ""},
		{"(*NYCbCrA).YOffset", Method, 6, ""},
		{"(*Paletted).At", Method, 0, ""},
		{"(*Paletted).Bounds", Method, 0, ""},
		{"(*Paletted).ColorIndexAt", Method, 0, ""},
		{"(*Paletted).ColorModel", Method, 0, ""},
		{"(*Paletted).Opaque", Method, 0, ""},
		{"(*Paletted).PixOffset", Method, 0, ""},
		{"(*Paletted).RGBA64At", Method, 17, ""},
		{"(*Paletted).Set", Method, 0, ""},
		{"(*Paletted).SetColorIndex", Method, 0, ""},
		{"(*Paletted).SetRGBA64", Method, 17, ""},
		{"(*Paletted).SubImage", Method, 0, ""},
		{"(*RGBA).At", Method, 0, ""},
		{"(*RGBA).Bounds", Method, 0, ""},
		{"(*RGBA).ColorModel", Method, 0, ""},
		{"(*RGBA).Opaque", Method, 0, ""},
		{"(*RGBA).PixOffset", Method, 0, ""},
		{"(*RGBA).RGBA64At", Method, 17, ""},
		{"(*RGBA).RGBAAt", Method, 4, ""},
		{"(*RGBA).Set", Method, 0, ""},
		{"(*RGBA).SetRGBA", Method, 0, ""},
		{"(*RGBA).SetRGBA64", Method, 17, ""},
		{"(*RGBA).SubImage", Method, 0, ""},
		{"(*RGBA64).At", Method, 0, ""},
		{"(*RGBA64).Bounds", Method, 0, ""},
		{"(*RGBA64).ColorModel", Method, 0, ""},
		{"(*RGBA64).Opaque", Method, 0, ""},
		{"(*RGBA64).PixOffset", Method, 0, ""},
		{"(*RGBA64).RGBA64At", Method, 4, ""},
		{"(*RGBA64).Set", Method, 0, ""},
		{"(*RGBA64).SetRGBA64", Method, 0, ""},
		{"(*RGBA64).SubImage", Method, 0, ""},
		{"(*Uniform).At", Method, 0, ""},
		{"(*Uniform).Bounds", Method, 0, ""},
		{"(*Uniform).ColorModel", Method, 0, ""},
		{"(*Uniform).Convert", Method, 0, ""},
		{"(*Uniform).Opaque", Method, 0, ""},
		{"(*Uniform).RGBA", Method, 0, ""},
		{"(*Uniform).RGBA64At", Method, 17, ""},
		{"(*YCbCr).At", Method, 0, ""},
		{"(*YCbCr).Bounds", Method, 0, ""},
		{"(*YCbCr).COffset", Method, 0, ""},
		{"(*YCbCr).ColorModel", Method, 0, ""},
		{"(*YCbCr).Opaque", Method, 0, ""},
		{"(*YCbCr).RGBA64At", Method, 17, ""},
		{"(*YCbCr).SubImage", Method, 0, ""},
		{"(*YCbCr).YCbCrAt", Method, 4, ""},
		{"(*YCbCr).YOffset", Method, 0, ""},
		{"(Image).At", Method, 0, ""},
		{"(Image).Bounds", Method, 0, ""},
		{"(Image).ColorModel", Method, 0, ""},
		{"(PalettedImage).At", Method, 0, ""},
		{"(PalettedImage).Bounds", Method, 0, ""},
		{"(PalettedImage).ColorIndexAt", Method, 0, ""},
		{"(PalettedImage).ColorModel", Method, 0, ""},
		{"(Point).Add", Method, 0, ""},
		{"(Point).Div", Method, 0, ""},
		{"(Point).Eq", Method, 0, ""},
		{"(Point).In", Method, 0, ""},
		{"(Point).Mod", Method, 0, ""},
		{"(Point).Mul", Method, 0, ""},
		{"(Point).String", Method, 0, ""},
		{"(Point).Sub", Method, 0, ""},
		{"(RGBA64Image).At", Method, 17, ""},
		{"(RGBA64Image).Bounds", Method, 17, ""},
		{"(RGBA64Image).ColorModel", Method, 17, ""},
		{"(RGBA64Image).RGBA64At", Method, 17, ""},
		{"(Rectangle).Add", Method, 0, ""},
		{"(Rectangle).At", Method, 5, ""},
		{"(Rectangle).Bounds", Method, 5, ""},
		{"(Rectangle).Canon", Method, 0, ""},
		{"(Rectangle).ColorModel", Method, 5, ""},
		{"(Rectangle).Dx", Method, 0, ""},
		{"(Rectangle).Dy", Method, 0, ""},
		{"(Rectangle).Empty", Method, 0, ""},
		{"(Rectangle).Eq", Method, 0, ""},
		{"(Rectangle).In", Method, 0, ""},
		{"(Rectangle).Inset", Method, 0, ""},
		{"(Rectangle).Intersect", Method, 0, ""},
		{"(Rectangle).Overlaps", Method, 0, ""},
		{"(Rectangle).RGBA64At", Method, 17, ""},
		{"(Rectangle).Size", Method, 0, ""},
		{"(Rectangle).String", Method, 0, ""},
		{"(Rectangle).Sub", Method, 0, ""},
		{"(Rectangle).Union", Method, 0, ""},
		{"(YCbCrSubsampleRatio).String", Method, 0, ""},
		{"Alpha", Type, 0, ""},
		{"Alpha.Pix", Field, 0, ""},
		{"Alpha.Rect", Field, 0, ""},
		{"Alpha.Stride", Field, 0, ""},
		{"Alpha16", Type, 0, ""},
		{"Alpha16.Pix", Field, 0, ""},
		{"Alpha16.Rect", Field, 0, ""},
		{"Alpha16.Stride", Field, 0, ""},
		{"Black", Var, 0, ""},
		{"CMYK", Type, 5, ""},
		{"CMYK.Pix", Field, 5, ""},
		{"CMYK.Rect", Field, 5, ""},
		{"CMYK.Stride", Field, 5, ""},
		{"Config", Type, 0, ""},
		{"Config.ColorModel", Field, 0, ""},
		{"Config.Height", Field, 0, ""},
		{"Config.Width", Field, 0, ""},
		{"Decode", Func, 0, "func(r io.Reader) (Image, string, error)"},
		{"DecodeConfig", Func, 0, "func(r io.Reader) (Config, string, error)"},
		{"ErrFormat", Var, 0, ""},
		{"Gray", Type, 0, ""},
		{"Gray.Pix", Field, 0, ""},
		{"Gray.Rect", Field, 0, ""},
		{"Gray.Stride", Field, 0, ""},
		{"Gray16", Type, 0, ""},
		{"Gray16.Pix", Field, 0, ""},
		{"Gray16.Rect", Field, 0, ""},
		{"Gray16.Stride", Field, 0, ""},
		{"Image", Type, 0, ""},
		{"NRGBA", Type, 0, ""},
		{"NRGBA.Pix", Field, 0, ""},
		{"NRGBA.Rect", Field, 0, ""},
		{"NRGBA.Stride", Field, 0, ""},
		{"NRGBA64", Type, 0, ""},
		{"NRGBA64.Pix", Field, 0, ""},
		{"NRGBA64.Rect", Field, 0, ""},
		{"NRGBA64.Stride", Field, 0, ""},
		{"NYCbCrA", Type, 6, ""},
		{"NYCbCrA.A", Field, 6, ""},
		{"NYCbCrA.AStride", Field, 6, ""},
		{"NYCbCrA.YCbCr", Field, 6, ""},
		{"NewAlpha", Func, 0, "func(r Rectangle) *Alpha"},
		{"NewAlpha16", Func, 0, "func(r Rectangle) *Alpha16"},
		{"NewCMYK", Func, 5, "func(r Rectangle) *CMYK"},
		{"NewGray", Func, 0, "func(r Rectangle) *Gray"},
		{"NewGray16", Func, 0, "func(r Rectangle) *Gray16"},
		{"NewNRGBA", Func, 0, "func(r Rectangle) *NRGBA"},
		{"NewNRGBA64", Func, 0, "func(r Rectangle) *NRGBA64"},
		{"NewNYCbCrA", Func, 6, "func(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *NYCbCrA"},
		{"NewPaletted", Func, 0, "func(r Rectangle, p color.Palette) *Paletted"},
		{"NewRGBA", Func, 0, "func(r Rectangle) *RGBA"},
		{"NewRGBA64", Func, 0, "func(r Rectangle) *RGBA64"},
		{"NewUniform", Func, 0, "func(c color.Color) *Uniform"},
		{"NewYCbCr", Func, 0, "func(r Rectangle, subsampleRatio YCbCrSubsampleRatio) *YCbCr"},
		{"Opaque", Var, 0, ""},
		{"Paletted", Type, 0, ""},
		{"Paletted.Palette", Field, 0, ""},
		{"Paletted.Pix", Field, 0, ""},
		{"Paletted.Rect", Field, 0, ""},
		{"Paletted.Stride", Field, 0, ""},
		{"PalettedImage", Type, 0, ""},
		{"Point", Type, 0, ""},
		{"Point.X", Field, 0, ""},
		{"Point.Y", Field, 0, ""},
		{"Pt", Func, 0, "func(X int, Y int) Point"},
		{"RGBA", Type, 0, ""},
		{"RGBA.Pix", Field, 0, ""},
		{"RGBA.Rect", Field, 0, ""},
		{"RGBA.Stride", Field, 0, ""},
		{"RGBA64", Type, 0, ""},
		{"RGBA64.Pix", Field, 0, ""},
		{"RGBA64.Rect", Field, 0, ""},
		{"RGBA64.Stride", Field, 0, ""},
		{"RGBA64Image", Type, 17, ""},
		{"Rect", Func, 0, "func(x0 int, y0 int, x1 int, y1 int) Rectangle"},
		{"Rectangle", Type, 0, ""},
		{"Rectangle.Max", Field, 0, ""},
		{"Rectangle.Min", Field, 0, ""},
		{"RegisterFormat", Func, 0, "func(name string, magic string, decode func(io.Reader) (Image, error), decodeConfig func(io.Reader) (Config, error))"},
		{"Transparent", Var, 0, ""},
		{"Uniform", Type, 0, ""},
		{"Uniform.C", Field, 0, ""},
		{"White", Var, 0, ""},
		{"YCbCr", Type, 0, ""},
		{"YCbCr.CStride", Field, 0, ""},
		{"YCbCr.Cb", Field, 0, ""},
		{"YCbCr.Cr", Field, 0, ""},
		{"YCbCr.Rect", Field, 0, ""},
		{"YCbCr.SubsampleRatio", Field, 0, ""},
		{"YCbCr.Y", Field, 0, ""},
		{"YCbCr.YStride", Field, 0, ""},
		{"YCbCrSubsampleRatio", Type, 0, ""},
		{"YCbCrSubsampleRatio410", Const, 5, ""},
		{"YCbCrSubsampleRatio411", Const, 5, ""},
		{"YCbCrSubsampleRatio420", Const, 0, ""},
		{"YCbCrSubsampleRatio422", Const, 0, ""},
		{"YCbCrSubsampleRatio440", Const, 1, ""},
		{"YCbCrSubsampleRatio444", Const, 0, ""},
		{"ZP", Var, 0, ""},
		{"ZR", Var, 0, ""},
	},
	"image/color": {
		{"(Alpha).RGBA", Method, 0, ""},
		{"(Alpha16).RGBA", Method, 0, ""},
		{"(CMYK).RGBA", Method, 5, ""},
		{"(Color).RGBA", Method, 0, ""},
		{"(Gray).RGBA", Method, 0, ""},
		{"(Gray16).RGBA", Method, 0, ""},
		{"(Model).Convert", Method, 0, ""},
		{"(NRGBA).RGBA", Method, 0, ""},
		{"(NRGBA64).RGBA", Method, 0, ""},
		{"(NYCbCrA).RGBA", Method, 6, ""},
		{"(Palette).Convert", Method, 0, ""},
		{"(Palette).Index", Method, 0, ""},
		{"(RGBA).RGBA", Method, 0, ""},
		{"(RGBA64).RGBA", Method, 0, ""},
		{"(YCbCr).RGBA", Method, 0, ""},
		{"Alpha", Type, 0, ""},
		{"Alpha.A", Field, 0, ""},
		{"Alpha16", Type, 0, ""},
		{"Alpha16.A", Field, 0, ""},
		{"Alpha16Model", Var, 0, ""},
		{"AlphaModel", Var, 0, ""},
		{"Black", Var, 0, ""},
		{"CMYK", Type, 5, ""},
		{"CMYK.C", Field, 5, ""},
		{"CMYK.K", Field, 5, ""},
		{"CMYK.M", Field, 5, ""},
		{"CMYK.Y", Field, 5, ""},
		{"CMYKModel", Var, 5, ""},
		{"CMYKToRGB", Func, 5, "func(c uint8, m uint8, y uint8, k uint8) (uint8, uint8, uint8)"},
		{"Color", Type, 0, ""},
		{"Gray", Type, 0, ""},
		{"Gray.Y", Field, 0, ""},
		{"Gray16", Type, 0, ""},
		{"Gray16.Y", Field, 0, ""},
		{"Gray16Model", Var, 0, ""},
		{"GrayModel", Var, 0, ""},
		{"Model", Type, 0, ""},
		{"ModelFunc", Func, 0, "func(f func(Color) Color) Model"},
		{"NRGBA", Type, 0, ""},
		{"NRGBA.A", Field, 0, ""},
		{"NRGBA.B", Field, 0, ""},
		{"NRGBA.G", Field, 0, ""},
		{"NRGBA.R", Field, 0, ""},
		{"NRGBA64", Type, 0, ""},
		{"NRGBA64.A", Field, 0, ""},
		{"NRGBA64.B", Field, 0, ""},
		{"NRGBA64.G", Field, 0, ""},
		{"NRGBA64.R", Field, 0, ""},
		{"NRGBA64Model", Var, 0, ""},
		{"NRGBAModel", Var, 0, ""},
		{"NYCbCrA", Type, 6, ""},
		{"NYCbCrA.A", Field, 6, ""},
		{"NYCbCrA.YCbCr", Field, 6, ""},
		{"NYCbCrAModel", Var, 6, ""},
		{"Opaque", Var, 0, ""},
		{"Palette", Type, 0, ""},
		{"RGBA", Type, 0, ""},
		{"RGBA.A", Field, 0, ""},
		{"RGBA.B", Field, 0, ""},
		{"RGBA.G", Field, 0, ""},
		{"RGBA.R", Field, 0, ""},
		{"RGBA64", Type, 0, ""},
		{"RGBA64.A", Field, 0, ""},
		{"RGBA64.B", Field, 0, ""},
		{"RGBA64.G", Field, 0, ""},
		{"RGBA64.R", Field, 0, ""},
		{"RGBA64Model", Var, 0, ""},
		{"RGBAModel", Var, 0, ""},
		{"RGBToCMYK", Func, 5, "func(r uint8, g uint8, b uint8) (uint8, uint8, uint8, uint8)"},
		{"RGBToYCbCr", Func, 0, "func(r uint8, g uint8, b uint8) (uint8, uint8, uint8)"},
		{"Transparent", Var, 0, ""},
		{"White", Var, 0, ""},
		{"YCbCr", Type, 0, ""},
		{"YCbCr.Cb", Field, 0, ""},
		{"YCbCr.Cr", Field, 0, ""},
		{"YCbCr.Y", Field, 0, ""},
		{"YCbCrModel", Var, 0, ""},
		{"YCbCrToRGB", Func, 0, "func(y uint8, cb uint8, cr uint8) (uint8, uint8, uint8)"},
	},
	"image/color/palette": {
		{"Plan9", Var, 2, ""},
		{"WebSafe", Var, 2, ""},
	},
	"image/draw": {
		{"(Drawer).Draw", Method, 2, ""},
		{"(Image).At", Method, 0, ""},
		{"(Image).Bounds", Method, 0, ""},
		{"(Image).ColorModel", Method, 0, ""},
		{"(Image).Set", Method, 0, ""},
		{"(Op).Draw", Method, 2, ""},
		{"(Quantizer).Quantize", Method, 2, ""},
		{"(RGBA64Image).At", Method, 17, ""},
		{"(RGBA64Image).Bounds", Method, 17, ""},
		{"(RGBA64Image).ColorModel", Method, 17, ""},
		{"(RGBA64Image).RGBA64At", Method, 17, ""},
		{"(RGBA64Image).Set", Method, 17, ""},
		{"(RGBA64Image).SetRGBA64", Method, 17, ""},
		{"Draw", Func, 0, "func(dst Image, r image.Rectangle, src image.Image, sp image.Point, op Op)"},
		{"DrawMask", Func, 0, "func(dst Image, r image.Rectangle, src image.Image, sp image.Point, mask image.Image, mp image.Point, op Op)"},
		{"Drawer", Type, 2, ""},
		{"FloydSteinberg", Var, 2, ""},
		{"Image", Type, 0, ""},
		{"Op", Type, 0, ""},
		{"Over", Const, 0, ""},
		{"Quantizer", Type, 2, ""},
		{"RGBA64Image", Type, 17, ""},
		{"Src", Const, 0, ""},
	},
	"image/gif": {
		{"Decode", Func, 0, "func(r io.Reader) (image.Image, error)"},
		{"DecodeAll", Func, 0, "func(r io.Reader) (*GIF, error)"},
		{"DecodeConfig", Func, 0, "func(r io.Reader) (image.Config, error)"},
		{"DisposalBackground", Const, 5, ""},
		{"DisposalNone", Const, 5, ""},
		{"DisposalPrevious", Const, 5, ""},
		{"Encode", Func, 2, "func(w io.Writer, m image.Image, o *Options) error"},
		{"EncodeAll", Func, 2, "func(w io.Writer, g *GIF) error"},
		{"GIF", Type, 0, ""},
		{"GIF.BackgroundIndex", Field, 5, ""},
		{"GIF.Config", Field, 5, ""},
		{"GIF.Delay", Field, 0, ""},
		{"GIF.Disposal", Field, 5, ""},
		{"GIF.Image", Field, 0, ""},
		{"GIF.LoopCount", Field, 0, ""},
		{"Options", Type, 2, ""},
		{"Options.Drawer", Field, 2, ""},
		{"Options.NumColors", Field, 2, ""},
		{"Options.Quantizer", Field, 2, ""},
	},
	"image/jpeg": {
		{"(FormatError).Error", Method, 0, ""},
		{"(Reader).Read", Method, 0, ""},
		{"(Reader).ReadByte", Method, 0, ""},
		{"(UnsupportedError).Error", Method, 0, ""},
		{"Decode", Func, 0, "func(r io.Reader) (image.Image, error)"},
		{"DecodeConfig", Func, 0, "func(r io.Reader) (image.Config, error)"},
		{"DefaultQuality", Const, 0, ""},
		{"Encode", Func, 0, "func(w io.Writer, m image.Image, o *Options) error"},
		{"FormatError", Type, 0, ""},
		{"Options", Type, 0, ""},
		{"Options.Quality", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"UnsupportedError", Type, 0, ""},
	},
	"image/png": {
		{"(*Encoder).Encode", Method, 4, ""},
		{"(EncoderBufferPool).Get", Method, 9, ""},
		{"(EncoderBufferPool).Put", Method, 9, ""},
		{"(FormatError).Error", Method, 0, ""},
		{"(UnsupportedError).Error", Method, 0, ""},
		{"BestCompression", Const, 4, ""},
		{"BestSpeed", Const, 4, ""},
		{"CompressionLevel", Type, 4, ""},
		{"Decode", Func, 0, "func(r io.Reader) (image.Image, error)"},
		{"DecodeConfig", Func, 0, "func(r io.Reader) (image.Config, error)"},
		{"DefaultCompression", Const, 4, ""},
		{"Encode", Func, 0, "func(w io.Writer, m image.Image) error"},
		{"Encoder", Type, 4, ""},
		{"Encoder.BufferPool", Field, 9, ""},
		{"Encoder.CompressionLevel", Field, 4, ""},
		{"EncoderBuffer", Type, 9, ""},
		{"EncoderBufferPool", Type, 9, ""},
		{"FormatError", Type, 0, ""},
		{"NoCompression", Const, 4, ""},
		{"UnsupportedError", Type, 0, ""},
	},
	"index/suffixarray": {
		{"(*Index).Bytes", Method, 0, ""},
		{"(*Index).FindAllIndex", Method, 0, ""},
		{"(*Index).Lookup", Method, 0, ""},
		{"(*Index).Read", Method, 0, ""},
		{"(*Index).Write", Method, 0, ""},
		{"Index", Type, 0, ""},
		{"New", Func, 0, "func(data []byte) *Index"},
	},
	"io": {
		{"(*LimitedReader).Read", Method, 0, ""},
		{"(*OffsetWriter).Seek", Method, 20, ""},
		{"(*OffsetWriter).Write", Method, 20, ""},
		{"(*OffsetWriter).WriteAt", Method, 20, ""},
		{"(*PipeReader).Close", Method, 0, ""},
		{"(*PipeReader).CloseWithError", Method, 0, ""},
		{"(*PipeReader).Read", Method, 0, ""},
		{"(*PipeWriter).Close", Method, 0, ""},
		{"(*PipeWriter).CloseWithError", Method, 0, ""},
		{"(*PipeWriter).Write", Method, 0, ""},
		{"(*SectionReader).Outer", Method, 22, ""},
		{"(*SectionReader).Read", Method, 0, ""},
		{"(*SectionReader).ReadAt", Method, 0, ""},
		{"(*SectionReader).Seek", Method, 0, ""},
		{"(*SectionReader).Size", Method, 0, ""},
		{"(ByteReader).ReadByte", Method, 0, ""},
		{"(ByteScanner).ReadByte", Method, 0, ""},
		{"(ByteScanner).UnreadByte", Method, 0, ""},
		{"(ByteWriter).WriteByte", Method, 1, ""},
		{"(Closer).Close", Method, 0, ""},
		{"(ReadCloser).Close", Method, 0, ""},
		{"(ReadCloser).Read", Method, 0, ""},
		{"(ReadSeekCloser).Close", Method, 16, ""},
		{"(ReadSeekCloser).Read", Method, 16, ""},
		{"(ReadSeekCloser).Seek", Method, 16, ""},
		{"(ReadSeeker).Read", Method, 0, ""},
		{"(ReadSeeker).Seek", Method, 0, ""},
		{"(ReadWriteCloser).Close", Method, 0, ""},
		{"(ReadWriteCloser).Read", Method, 0, ""},
		{"(ReadWriteCloser).Write", Method, 0, ""},
		{"(ReadWriteSeeker).Read", Method, 0, ""},
		{"(ReadWriteSeeker).Seek", Method, 0, ""},
		{"(ReadWriteSeeker).Write", Method, 0, ""},
		{"(ReadWriter).Read", Method, 0, ""},
		{"(ReadWriter).Write", Method, 0, ""},
		{"(Reader).Read", Method, 0, ""},
		{"(ReaderAt).ReadAt", Method, 0, ""},
		{"(ReaderFrom).ReadFrom", Method, 0, ""},
		{"(RuneReader).ReadRune", Method, 0, ""},
		{"(RuneScanner).ReadRune", Method, 0, ""},
		{"(RuneScanner).UnreadRune", Method, 0, ""},
		{"(Seeker).Seek", Method, 0, ""},
		{"(StringWriter).WriteString", Method, 12, ""},
		{"(WriteCloser).Close", Method, 0, ""},
		{"(WriteCloser).Write", Method, 0, ""},
		{"(WriteSeeker).Seek", Method, 0, ""},
		{"(WriteSeeker).Write", Method, 0, ""},
		{"(Writer).Write", Method, 0, ""},
		{"(WriterAt).WriteAt", Method, 0, ""},
		{"(WriterTo).WriteTo", Method, 0, ""},
		{"ByteReader", Type, 0, ""},
		{"ByteScanner", Type, 0, ""},
		{"ByteWriter", Type, 1, ""},
		{"Closer", Type, 0, ""},
		{"Copy", Func, 0, "func(dst Writer, src Reader) (written int64, err error)"},
		{"CopyBuffer", Func, 5, "func(dst Writer, src Reader, buf []byte) (written int64, err error)"},
		{"CopyN", Func, 0, "func(dst Writer, src Reader, n int64) (written int64, err error)"},
		{"Discard", Var, 16, ""},
		{"EOF", Var, 0, ""},
		{"ErrClosedPipe", Var, 0, ""},
		{"ErrNoProgress", Var, 1, ""},
		{"ErrShortBuffer", Var, 0, ""},
		{"ErrShortWrite", Var, 0, ""},
		{"ErrUnexpectedEOF", Var, 0, ""},
		{"LimitReader", Func, 0, "func(r Reader, n int64) Reader"},
		{"LimitedReader", Type, 0, ""},
		{"LimitedReader.N", Field, 0, ""},
		{"LimitedReader.R", Field, 0, ""},
		{"MultiReader", Func, 0, "func(readers ...Reader) Reader"},
		{"MultiWriter", Func, 0, "func(writers ...Writer) Writer"},
		{"NewOffsetWriter", Func, 20, "func(w WriterAt, off int64) *OffsetWriter"},
		{"NewSectionReader", Func, 0, "func(r ReaderAt, off int64, n int64) *SectionReader"},
		{"NopCloser", Func, 16, "func(r Reader) ReadCloser"},
		{"OffsetWriter", Type, 20, ""},
		{"Pipe", Func, 0, "func() (*PipeReader, *PipeWriter)"},
		{"PipeReader", Type, 0, ""},
		{"PipeWriter", Type, 0, ""},
		{"ReadAll", Func, 16, "func(r Reader) ([]byte, error)"},
		{"ReadAtLeast", Func, 0, "func(r Reader, buf []byte, min int) (n int, err error)"},
		{"ReadCloser", Type, 0, ""},
		{"ReadFull", Func, 0, "func(r Reader, buf []byte) (n int, err error)"},
		{"ReadSeekCloser", Type, 16, ""},
		{"ReadSeeker", Type, 0, ""},
		{"ReadWriteCloser", Type, 0, ""},
		{"ReadWriteSeeker", Type, 0, ""},
		{"ReadWriter", Type, 0, ""},
		{"Reader", Type, 0, ""},
		{"ReaderAt", Type, 0, ""},
		{"ReaderFrom", Type, 0, ""},
		{"RuneReader", Type, 0, ""},
		{"RuneScanner", Type, 0, ""},
		{"SectionReader", Type, 0, ""},
		{"SeekCurrent", Const, 7, ""},
		{"SeekEnd", Const, 7, ""},
		{"SeekStart", Const, 7, ""},
		{"Seeker", Type, 0, ""},
		{"StringWriter", Type, 12, ""},
		{"TeeReader", Func, 0, "func(r Reader, w Writer) Reader"},
		{"WriteCloser", Type, 0, ""},
		{"WriteSeeker", Type, 0, ""},
		{"WriteString", Func, 0, "func(w Writer, s string) (n int, err error)"},
		{"Writer", Type, 0, ""},
		{"WriterAt", Type, 0, ""},
		{"WriterTo", Type, 0, ""},
	},
	"io/fs": {
		{"(*PathError).Error", Method, 16, ""},
		{"(*PathError).Timeout", Method, 16, ""},
		{"(*PathError).Unwrap", Method, 16, ""},
		{"(DirEntry).Info", Method, 16, ""},
		{"(DirEntry).IsDir", Method, 16, ""},
		{"(DirEntry).Name", Method, 16, ""},
		{"(DirEntry).Type", Method, 16, ""},
		{"(FS).Open", Method, 16, ""},
		{"(File).Close", Method, 16, ""},
		{"(File).Read", Method, 16, ""},
		{"(File).Stat", Method, 16, ""},
		{"(FileInfo).IsDir", Method, 16, ""},
		{"(FileInfo).ModTime", Method, 16, ""},
		{"(FileInfo).Mode", Method, 16, ""},
		{"(FileInfo).Name", Method, 16, ""},
		{"(FileInfo).Size", Method, 16, ""},
		{"(FileInfo).Sys", Method, 16, ""},
		{"(FileMode).IsDir", Method, 16, ""},
		{"(FileMode).IsRegular", Method, 16, ""},
		{"(FileMode).Perm", Method, 16, ""},
		{"(FileMode).String", Method, 16, ""},
		{"(FileMode).Type", Method, 16, ""},
		{"(GlobFS).Glob", Method, 16, ""},
		{"(GlobFS).Open", Method, 16, ""},
		{"(ReadDirFS).Open", Method, 16, ""},
		{"(ReadDirFS).ReadDir", Method, 16, ""},
		{"(ReadDirFile).Close", Method, 16, ""},
		{"(ReadDirFile).Read", Method, 16, ""},
		{"(ReadDirFile).ReadDir", Method, 16, ""},
		{"(ReadDirFile).Stat", Method, 16, ""},
		{"(ReadFileFS).Open", Method, 16, ""},
		{"(ReadFileFS).ReadFile", Method, 16, ""},
		{"(ReadLinkFS).Lstat", Method, 25, ""},
		{"(ReadLinkFS).Open", Method, 25, ""},
		{"(ReadLinkFS).ReadLink", Method, 25, ""},
		{"(StatFS).Open", Method, 16, ""},
		{"(StatFS).Stat", Method, 16, ""},
		{"(SubFS).Open", Method, 16, ""},
		{"(SubFS).Sub", Method, 16, ""},
		{"DirEntry", Type, 16, ""},
		{"ErrClosed", Var, 16, ""},
		{"ErrExist", Var, 16, ""},
		{"ErrInvalid", Var, 16, ""},
		{"ErrNotExist", Var, 16, ""},
		{"ErrPermission", Var, 16, ""},
		{"FS", Type, 16, ""},
		{"File", Type, 16, ""},
		{"FileInfo", Type, 16, ""},
		{"FileInfoToDirEntry", Func, 17, "func(info FileInfo) DirEntry"},
		{"FileMode", Type, 16, ""},
		{"FormatDirEntry", Func, 21, "func(dir DirEntry) string"},
		{"FormatFileInfo", Func, 21, "func(info FileInfo) string"},
		{"Glob", Func, 16, "func(fsys FS, pattern string) (matches []string, err error)"},
		{"GlobFS", Type, 16, ""},
		{"Lstat", Func, 25, "func(fsys FS, name string) (FileInfo, error)"},
		{"ModeAppend", Const, 16, ""},
		{"ModeCharDevice", Const, 16, ""},
		{"ModeDevice", Const, 16, ""},
		{"ModeDir", Const, 16, ""},
		{"ModeExclusive", Const, 16, ""},
		{"ModeIrregular", Const, 16, ""},
		{"ModeNamedPipe", Const, 16, ""},
		{"ModePerm", Const, 16, ""},
		{"ModeSetgid", Const, 16, ""},
		{"ModeSetuid", Const, 16, ""},
		{"ModeSocket", Const, 16, ""},
		{"ModeSticky", Const, 16, ""},
		{"ModeSymlink", Const, 16, ""},
		{"ModeTemporary", Const, 16, ""},
		{"ModeType", Const, 16, ""},
		{"PathError", Type, 16, ""},
		{"PathError.Err", Field, 16, ""},
		{"PathError.Op", Field, 16, ""},
		{"PathError.Path", Field, 16, ""},
		{"ReadDir", Func, 16, "func(fsys FS, name string) ([]DirEntry, error)"},
		{"ReadDirFS", Type, 16, ""},
		{"ReadDirFile", Type, 16, ""},
		{"ReadFile", Func, 16, "func(fsys FS, name string) ([]byte, error)"},
		{"ReadFileFS", Type, 16, ""},
		{"ReadLink", Func, 25, "func(fsys FS, name string) (string, error)"},
		{"ReadLinkFS", Type, 25, ""},
		{"SkipAll", Var, 20, ""},
		{"SkipDir", Var, 16, ""},
		{"Stat", Func, 16, "func(fsys FS, name string) (FileInfo, error)"},
		{"StatFS", Type, 16, ""},
		{"Sub", Func, 16, "func(fsys FS, dir string) (FS, error)"},
		{"SubFS", Type, 16, ""},
		{"ValidPath", Func, 16, "func(name string) bool"},
		{"WalkDir", Func, 16, "func(fsys FS, root string, fn WalkDirFunc) error"},
		{"WalkDirFunc", Type, 16, ""},
	},
	"io/ioutil": {
		{"Discard", Var, 0, ""},
		{"NopCloser", Func, 0, "func(r io.Reader) io.ReadCloser"},
		{"ReadAll", Func, 0, "func(r io.Reader) ([]byte, error)"},
		{"ReadDir", Func, 0, "func(dirname string) ([]fs.FileInfo, error)"},
		{"ReadFile", Func, 0, "func(filename string) ([]byte, error)"},
		{"TempDir", Func, 0, "func(dir string, pattern string) (name string, err error)"},
		{"TempFile", Func, 0, "func(dir string, pattern string) (f *os.File, err error)"},
		{"WriteFile", Func, 0, "func(filename string, data []byte, perm fs.FileMode) error"},
	},
	"iter": {
		{"Pull", Func, 23, "func[V any](seq Seq[V]) (next func() (V, bool), stop func())"},
		{"Pull2", Func, 23, "func[K, V any](seq Seq2[K, V]) (next func() (K, V, bool), stop func())"},
		{"Seq", Type, 23, ""},
		{"Seq2", Type, 23, ""},
	},
	"log": {
		{"(*Logger).Fatal", Method, 0, ""},
		{"(*Logger).Fatalf", Method, 0, ""},
		{"(*Logger).Fatalln", Method, 0, ""},
		{"(*Logger).Flags", Method, 0, ""},
		{"(*Logger).Output", Method, 0, ""},
		{"(*Logger).Panic", Method, 0, ""},
		{"(*Logger).Panicf", Method, 0, ""},
		{"(*Logger).Panicln", Method, 0, ""},
		{"(*Logger).Prefix", Method, 0, ""},
		{"(*Logger).Print", Method, 0, ""},
		{"(*Logger).Printf", Method, 0, ""},
		{"(*Logger).Println", Method, 0, ""},
		{"(*Logger).SetFlags", Method, 0, ""},
		{"(*Logger).SetOutput", Method, 5, ""},
		{"(*Logger).SetPrefix", Method, 0, ""},
		{"(*Logger).Writer", Method, 12, ""},
		{"Default", Func, 16, "func() *Logger"},
		{"Fatal", Func, 0, "func(v ...any)"},
		{"Fatalf", Func, 0, "func(format string, v ...any)"},
		{"Fatalln", Func, 0, "func(v ...any)"},
		{"Flags", Func, 0, "func() int"},
		{"LUTC", Const, 5, ""},
		{"Ldate", Const, 0, ""},
		{"Llongfile", Const, 0, ""},
		{"Lmicroseconds", Const, 0, ""},
		{"Lmsgprefix", Const, 14, ""},
		{"Logger", Type, 0, ""},
		{"Lshortfile", Const, 0, ""},
		{"LstdFlags", Const, 0, ""},
		{"Ltime", Const, 0, ""},
		{"New", Func, 0, "func(out io.Writer, prefix string, flag int) *Logger"},
		{"Output", Func, 5, "func(calldepth int, s string) error"},
		{"Panic", Func, 0, "func(v ...any)"},
		{"Panicf", Func, 0, "func(format string, v ...any)"},
		{"Panicln", Func, 0, "func(v ...any)"},
		{"Prefix", Func, 0, "func() string"},
		{"Print", Func, 0, "func(v ...any)"},
		{"Printf", Func, 0, "func(format string, v ...any)"},
		{"Println", Func, 0, "func(v ...any)"},
		{"SetFlags", Func, 0, "func(flag int)"},
		{"SetOutput", Func, 0, "func(w io.Writer)"},
		{"SetPrefix", Func, 0, "func(prefix string)"},
		{"Writer", Func, 13, "func() io.Writer"},
	},
	"log/slog": {
		{"(*JSONHandler).Enabled", Method, 21, ""},
		{"(*JSONHandler).Handle", Method, 21, ""},
		{"(*JSONHandler).WithAttrs", Method, 21, ""},
		{"(*JSONHandler).WithGroup", Method, 21, ""},
		{"(*Level).UnmarshalJSON", Method, 21, ""},
		{"(*Level).UnmarshalText", Method, 21, ""},
		{"(*LevelVar).AppendText", Method, 24, ""},
		{"(*LevelVar).Level", Method, 21, ""},
		{"(*LevelVar).MarshalText", Method, 21, ""},
		{"(*LevelVar).Set", Method, 21, ""},
		{"(*LevelVar).String", Method, 21, ""},
		{"(*LevelVar).UnmarshalText", Method, 21, ""},
		{"(*Logger).Debug", Method, 21, ""},
		{"(*Logger).DebugContext", Method, 21, ""},
		{"(*Logger).Enabled", Method, 21, ""},
		{"(*Logger).Error", Method, 21, ""},
		{"(*Logger).ErrorContext", Method, 21, ""},
		{"(*Logger).Handler", Method, 21, ""},
		{"(*Logger).Info", Method, 21, ""},
		{"(*Logger).InfoContext", Method, 21, ""},
		{"(*Logger).Log", Method, 21, ""},
		{"(*Logger).LogAttrs", Method, 21, ""},
		{"(*Logger).Warn", Method, 21, ""},
		{"(*Logger).WarnContext", Method, 21, ""},
		{"(*Logger).With", Method, 21, ""},
		{"(*Logger).WithGroup", Method, 21, ""},
		{"(*MultiHandler).Enabled", Method, 26, ""},
		{"(*MultiHandler).Handle", Method, 26, ""},
		{"(*MultiHandler).WithAttrs", Method, 26, ""},
		{"(*MultiHandler).WithGroup", Method, 26, ""},
		{"(*Record).Add", Method, 21, ""},
		{"(*Record).AddAttrs", Method, 21, ""},
		{"(*TextHandler).Enabled", Method, 21, ""},
		{"(*TextHandler).Handle", Method, 21, ""},
		{"(*TextHandler).WithAttrs", Method, 21, ""},
		{"(*TextHandler).WithGroup", Method, 21, ""},
		{"(Attr).Equal", Method, 21, ""},
		{"(Attr).String", Method, 21, ""},
		{"(Handler).Enabled", Method, 21, ""},
		{"(Handler).Handle", Method, 21, ""},
		{"(Handler).WithAttrs", Method, 21, ""},
		{"(Handler).WithGroup", Method, 21, ""},
		{"(Kind).String", Method, 21, ""},
		{"(Level).AppendText", Method, 24, ""},
		{"(Level).Level", Method, 21, ""},
		{"(Level).MarshalJSON", Method, 21, ""},
		{"(Level).MarshalText", Method, 21, ""},
		{"(Level).String", Method, 21, ""},
		{"(Leveler).Level", Method, 21, ""},
		{"(LogValuer).LogValue", Method, 21, ""},
		{"(Record).Attrs", Method, 21, ""},
		{"(Record).Clone", Method, 21, ""},
		{"(Record).NumAttrs", Method, 21, ""},
		{"(Record).Source", Method, 25, ""},
		{"(Value).Any", Method, 21, ""},
		{"(Value).Bool", Method, 21, ""},
		{"(Value).Duration", Method, 21, ""},
		{"(Value).Equal", Method, 21, ""},
		{"(Value).Float64", Method, 21, ""},
		{"(Value).Group", Method, 21, ""},
		{"(Value).Int64", Method, 21, ""},
		{"(Value).Kind", Method, 21, ""},
		{"(Value).LogValuer", Method, 21, ""},
		{"(Value).Resolve", Method, 21, ""},
		{"(Value).String", Method, 21, ""},
		{"(Value).Time", Method, 21, ""},
		{"(Value).Uint64", Method, 21, ""},
		{"Any", Func, 21, "func(key string, value any) Attr"},
		{"AnyValue", Func, 21, "func(v any) Value"},
		{"Attr", Type, 21, ""},
		{"Attr.Key", Field, 21, ""},
		{"Attr.Value", Field, 21, ""},
		{"Bool", Func, 21, "func(key string, v bool) Attr"},
		{"BoolValue", Func, 21, "func(v bool) Value"},
		{"Debug", Func, 21, "func(msg string, args ...any)"},
		{"DebugContext", Func, 21, "func(ctx context.Context, msg string, args ...any)"},
		{"Default", Func, 21, "func() *Logger"},
		{"DiscardHandler", Var, 24, ""},
		{"Duration", Func, 21, "func(key string, v time.Duration) Attr"},
		{"DurationValue", Func, 21, "func(v time.Duration) Value"},
		{"Error", Func, 21, "func(msg string, args ...any)"},
		{"ErrorContext", Func, 21, "func(ctx context.Context, msg string, args ...any)"},
		{"Float64", Func, 21, "func(key string, v float64) Attr"},
		{"Float64Value", Func, 21, "func(v float64) Value"},
		{"Group", Func, 21, "func(key string, args ...any) Attr"},
		{"GroupAttrs", Func, 25, "func(key string, attrs ...Attr) Attr"},
		{"GroupValue", Func, 21, "func(as ...Attr) Value"},
		{"Handler", Type, 21, ""},
		{"HandlerOptions", Type, 21, ""},
		{"HandlerOptions.AddSource", Field, 21, ""},
		{"HandlerOptions.Level", Field, 21, ""},
		{"HandlerOptions.ReplaceAttr", Field, 21, ""},
		{"Info", Func, 21, "func(msg string, args ...any)"},
		{"InfoContext", Func, 21, "func(ctx context.Context, msg string, args ...any)"},
		{"Int", Func, 21, "func(key string, value int) Attr"},
		{"Int64", Func, 21, "func(key string, value int64) Attr"},
		{"Int64Value", Func, 21, "func(v int64) Value"},
		{"IntValue", Func, 21, "func(v int) Value"},
		{"JSONHandler", Type, 21, ""},
		{"Kind", Type, 21, ""},
		{"KindAny", Const, 21, ""},
		{"KindBool", Const, 21, ""},
		{"KindDuration", Const, 21, ""},
		{"KindFloat64", Const, 21, ""},
		{"KindGroup", Const, 21, ""},
		{"KindInt64", Const, 21, ""},
		{"KindLogValuer", Const, 21, ""},
		{"KindString", Const, 21, ""},
		{"KindTime", Const, 21, ""},
		{"KindUint64", Const, 21, ""},
		{"Level", Type, 21, ""},
		{"LevelDebug", Const, 21, ""},
		{"LevelError", Const, 21, ""},
		{"LevelInfo", Const, 21, ""},
		{"LevelKey", Const, 21, ""},
		{"LevelVar", Type, 21, ""},
		{"LevelWarn", Const, 21, ""},
		{"Leveler", Type, 21, ""},
		{"Log", Func, 21, "func(ctx context.Context, level Level, msg string, args ...any)"},
		{"LogAttrs", Func, 21, "func(ctx context.Context, level Level, msg string, attrs ...Attr)"},
		{"LogValuer", Type, 21, ""},
		{"Logger", Type, 21, ""},
		{"MessageKey", Const, 21, ""},
		{"MultiHandler", Type, 26, ""},
		{"New", Func, 21, "func(h Handler) *Logger"},
		{"NewJSONHandler", Func, 21, "func(w io.Writer, opts *HandlerOptions) *JSONHandler"},
		{"NewLogLogger", Func, 21, "func(h Handler, level Level) *log.Logger"},
		{"NewMultiHandler", Func, 26, "func(handlers ...Handler) *MultiHandler"},
		{"NewRecord", Func, 21, "func(t time.Time, level Level, msg string, pc uintptr) Record"},
		{"NewTextHandler", Func, 21, "func(w io.Writer, opts *HandlerOptions) *TextHandler"},
		{"Record", Type, 21, ""},
		{"Record.Level", Field, 21, ""},
		{"Record.Message", Field, 21, ""},
		{"Record.PC", Field, 21, ""},
		{"Record.Time", Field, 21, ""},
		{"SetDefault", Func, 21, "func(l *Logger)"},
		{"SetLogLoggerLevel", Func, 22, "func(level Level) (oldLevel Level)"},
		{"Source", Type, 21, ""},
		{"Source.File", Field, 21, ""},
		{"Source.Function", Field, 21, ""},
		{"Source.Line", Field, 21, ""},
		{"SourceKey", Const, 21, ""},
		{"String", Func, 21, "func(key string, value string) Attr"},
		{"StringValue", Func, 21, "func(value string) Value"},
		{"TextHandler", Type, 21, ""},
		{"Time", Func, 21, "func(key string, v time.Time) Attr"},
		{"TimeKey", Const, 21, ""},
		{"TimeValue", Func, 21, "func(v time.Time) Value"},
		{"Uint64", Func, 21, "func(key string, v uint64) Attr"},
		{"Uint64Value", Func, 21, "func(v uint64) Value"},
		{"Value", Type, 21, ""},
		{"Warn", Func, 21, "func(msg string, args ...any)"},
		{"WarnContext", Func, 21, "func(ctx context.Context, msg string, args ...any)"},
		{"With", Func, 21, "func(args ...any) *Logger"},
	},
	"log/syslog": {
		{"(*Writer).Alert", Method, 0, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).Crit", Method, 0, ""},
		{"(*Writer).Debug", Method, 0, ""},
		{"(*Writer).Emerg", Method, 0, ""},
		{"(*Writer).Err", Method, 0, ""},
		{"(*Writer).Info", Method, 0, ""},
		{"(*Writer).Notice", Method, 0, ""},
		{"(*Writer).Warning", Method, 0, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"Dial", Func, 0, "func(network string, raddr string, priority Priority, tag string) (*Writer, error)"},
		{"LOG_ALERT", Const, 0, ""},
		{"LOG_AUTH", Const, 1, ""},
		{"LOG_AUTHPRIV", Const, 1, ""},
		{"LOG_CRIT", Const, 0, ""},
		{"LOG_CRON", Const, 1, ""},
		{"LOG_DAEMON", Const, 1, ""},
		{"LOG_DEBUG", Const, 0, ""},
		{"LOG_EMERG", Const, 0, ""},
		{"LOG_ERR", Const, 0, ""},
		{"LOG_FTP", Const, 1, ""},
		{"LOG_INFO", Const, 0, ""},
		{"LOG_KERN", Const, 1, ""},
		{"LOG_LOCAL0", Const, 1, ""},
		{"LOG_LOCAL1", Const, 1, ""},
		{"LOG_LOCAL2", Const, 1, ""},
		{"LOG_LOCAL3", Const, 1, ""},
		{"LOG_LOCAL4", Const, 1, ""},
		{"LOG_LOCAL5", Const, 1, ""},
		{"LOG_LOCAL6", Const, 1, ""},
		{"LOG_LOCAL7", Const, 1, ""},
		{"LOG_LPR", Const, 1, ""},
		{"LOG_MAIL", Const, 1, ""},
		{"LOG_NEWS", Const, 1, ""},
		{"LOG_NOTICE", Const, 0, ""},
		{"LOG_SYSLOG", Const, 1, ""},
		{"LOG_USER", Const, 1, ""},
		{"LOG_UUCP", Const, 1, ""},
		{"LOG_WARNING", Const, 0, ""},
		{"New", Func, 0, "func(priority Priority, tag string) (*Writer, error)"},
		{"NewLogger", Func, 0, "func(p Priority, logFlag int) (*log.Logger, error)"},
		{"Priority", Type, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"maps": {
		{"All", Func, 23, "func[Map ~map[K]V, K comparable, V any](m Map) iter.Seq2[K, V]"},
		{"Clone", Func, 21, "func[M ~map[K]V, K comparable, V any](m M) M"},
		{"Collect", Func, 23, "func[K comparable, V any](seq iter.Seq2[K, V]) map[K]V"},
		{"Copy", Func, 21, "func[M1 ~map[K]V, M2 ~map[K]V, K comparable, V any](dst M1, src M2)"},
		{"DeleteFunc", Func, 21, "func[M ~map[K]V, K comparable, V any](m M, del func(K, V) bool)"},
		{"Equal", Func, 21, "func[M1, M2 ~map[K]V, K, V comparable](m1 M1, m2 M2) bool"},
		{"EqualFunc", Func, 21, "func[M1 ~map[K]V1, M2 ~map[K]V2, K comparable, V1, V2 any](m1 M1, m2 M2, eq func(V1, V2) bool) bool"},
		{"Insert", Func, 23, "func[Map ~map[K]V, K comparable, V any](m Map, seq iter.Seq2[K, V])"},
		{"Keys", Func, 23, "func[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[K]"},
		{"Values", Func, 23, "func[Map ~map[K]V, K comparable, V any](m Map) iter.Seq[V]"},
	},
	"math": {
		{"Abs", Func, 0, "func(x float64) float64"},
		{"Acos", Func, 0, "func(x float64) float64"},
		{"Acosh", Func, 0, "func(x float64) float64"},
		{"Asin", Func, 0, "func(x float64) float64"},
		{"Asinh", Func, 0, "func(x float64) float64"},
		{"Atan", Func, 0, "func(x float64) float64"},
		{"Atan2", Func, 0, "func(y float64, x float64) float64"},
		{"Atanh", Func, 0, "func(x float64) float64"},
		{"Cbrt", Func, 0, "func(x float64) float64"},
		{"Ceil", Func, 0, "func(x float64) float64"},
		{"Copysign", Func, 0, "func(f float64, sign float64) float64"},
		{"Cos", Func, 0, "func(x float64) float64"},
		{"Cosh", Func, 0, "func(x float64) float64"},
		{"Dim", Func, 0, "func(x float64, y float64) float64"},
		{"E", Const, 0, ""},
		{"Erf", Func, 0, "func(x float64) float64"},
		{"Erfc", Func, 0, "func(x float64) float64"},
		{"Erfcinv", Func, 10, "func(x float64) float64"},
		{"Erfinv", Func, 10, "func(x float64) float64"},
		{"Exp", Func, 0, "func(x float64) float64"},
		{"Exp2", Func, 0, "func(x float64) float64"},
		{"Expm1", Func, 0, "func(x float64) float64"},
		{"FMA", Func, 14, "func(x float64, y float64, z float64) float64"},
		{"Float32bits", Func, 0, "func(f float32) uint32"},
		{"Float32frombits", Func, 0, "func(b uint32) float32"},
		{"Float64bits", Func, 0, "func(f float64) uint64"},
		{"Float64frombits", Func, 0, "func(b uint64) float64"},
		{"Floor", Func, 0, "func(x float64) float64"},
		{"Frexp", Func, 0, "func(f float64) (frac float64, exp int)"},
		{"Gamma", Func, 0, "func(x float64) float64"},
		{"Hypot", Func, 0, "func(p float64, q float64) float64"},
		{"Ilogb", Func, 0, "func(x float64) int"},
		{"Inf", Func, 0, "func(sign int) float64"},
		{"IsInf", Func, 0, "func(f float64, sign int) bool"},
		{"IsNaN", Func, 0, "func(f float64) (is bool)"},
		{"J0", Func, 0, "func(x float64) float64"},
		{"J1", Func, 0, "func(x float64) float64"},
		{"Jn", Func, 0, "func(n int, x float64) float64"},
		{"Ldexp", Func, 0, "func(frac float64, exp int) float64"},
		{"Lgamma", Func, 0, "func(x float64) (lgamma float64, sign int)"},
		{"Ln10", Const, 0, ""},
		{"Ln2", Const, 0, ""},
		{"Log", Func, 0, "func(x float64) float64"},
		{"Log10", Func, 0, "func(x float64) float64"},
		{"Log10E", Const, 0, ""},
		{"Log1p", Func, 0, "func(x float64) float64"},
		{"Log2", Func, 0, "func(x float64) float64"},
		{"Log2E", Const, 0, ""},
		{"Logb", Func, 0, "func(x float64) float64"},
		{"Max", Func, 0, "func(x float64, y float64) float64"},
		{"MaxFloat32", Const, 0, ""},
		{"MaxFloat64", Const, 0, ""},
		{"MaxInt", Const, 17, ""},
		{"MaxInt16", Const, 0, ""},
		{"MaxInt32", Const, 0, ""},
		{"MaxInt64", Const, 0, ""},
		{"MaxInt8", Const, 0, ""},
		{"MaxUint", Const, 17, ""},
		{"MaxUint16", Const, 0, ""},
		{"MaxUint32", Const, 0, ""},
		{"MaxUint64", Const, 0, ""},
		{"MaxUint8", Const, 0, ""},
		{"Min", Func, 0, "func(x float64, y float64) float64"},
		{"MinInt", Const, 17, ""},
		{"MinInt16", Const, 0, ""},
		{"MinInt32", Const, 0, ""},
		{"MinInt64", Const, 0, ""},
		{"MinInt8", Const, 0, ""},
		{"Mod", Func, 0, "func(x float64, y float64) float64"},
		{"Modf", Func, 0, "func(f float64) (integer float64, fractional float64)"},
		{"NaN", Func, 0, "func() float64"},
		{"Nextafter", Func, 0, "func(x float64, y float64) (r float64)"},
		{"Nextafter32", Func, 4, "func(x float32, y float32) (r float32)"},
		{"Phi", Const, 0, ""},
		{"Pi", Const, 0, ""},
		{"Pow", Func, 0, "func(x float64, y float64) float64"},
		{"Pow10", Func, 0, "func(n int) float64"},
		{"Remainder", Func, 0, "func(x float64, y float64) float64"},
		{"Round", Func, 10, "func(x float64) float64"},
		{"RoundToEven", Func, 10, "func(x float64) float64"},
		{"Signbit", Func, 0, "func(x float64) bool"},
		{"Sin", Func, 0, "func(x float64) float64"},
		{"Sincos", Func, 0, "func(x float64) (sin float64, cos float64)"},
		{"Sinh", Func, 0, "func(x float64) float64"},
		{"SmallestNonzeroFloat32", Const, 0, ""},
		{"SmallestNonzeroFloat64", Const, 0, ""},
		{"Sqrt", Func, 0, "func(x float64) float64"},
		{"Sqrt2", Const, 0, ""},
		{"SqrtE", Const, 0, ""},
		{"SqrtPhi", Const, 0, ""},
		{"SqrtPi", Const, 0, ""},
		{"Tan", Func, 0, "func(x float64) float64"},
		{"Tanh", Func, 0, "func(x float64) float64"},
		{"Trunc", Func, 0, "func(x float64) float64"},
		{"Y0", Func, 0, "func(x float64) float64"},
		{"Y1", Func, 0, "func(x float64) float64"},
		{"Yn", Func, 0, "func(n int, x float64) float64"},
	},
	"math/big": {
		{"(*Float).Abs", Method, 5, ""},
		{"(*Float).Acc", Method, 5, ""},
		{"(*Float).Add", Method, 5, ""},
		{"(*Float).Append", Method, 5, ""},
		{"(*Float).AppendText", Method, 24, ""},
		{"(*Float).Cmp", Method, 5, ""},
		{"(*Float).Copy", Method, 5, ""},
		{"(*Float).Float32", Method, 5, ""},
		{"(*Float).Float64", Method, 5, ""},
		{"(*Float).Format", Method, 5, ""},
		{"(*Float).GobDecode", Method, 7, ""},
		{"(*Float).GobEncode", Method, 7, ""},
		{"(*Float).Int", Method, 5, ""},
		{"(*Float).Int64", Method, 5, ""},
		{"(*Float).IsInf", Method, 5, ""},
		{"(*Float).IsInt", Method, 5, ""},
		{"(*Float).MantExp", Method, 5, ""},
		{"(*Float).MarshalText", Method, 6, ""},
		{"(*Float).MinPrec", Method, 5, ""},
		{"(*Float).Mode", Method, 5, ""},
		{"(*Float).Mul", Method, 5, ""},
		{"(*Float).Neg", Method, 5, ""},
		{"(*Float).Parse", Method, 5, ""},
		{"(*Float).Prec", Method, 5, ""},
		{"(*Float).Quo", Method, 5, ""},
		{"(*Float).Rat", Method, 5, ""},
		{"(*Float).Scan", Method, 8, ""},
		{"(*Float).Set", Method, 5, ""},
		{"(*Float).SetFloat64", Method, 5, ""},
		{"(*Float).SetInf", Method, 5, ""},
		{"(*Float).SetInt", Method, 5, ""},
		{"(*Float).SetInt64", Method, 5, ""},
		{"(*Float).SetMantExp", Method, 5, ""},
		{"(*Float).SetMode", Method, 5, ""},
		{"(*Float).SetPrec", Method, 5, ""},
		{"(*Float).SetRat", Method, 5, ""},
		{"(*Float).SetString", Method, 5, ""},
		{"(*Float).SetUint64", Method, 5, ""},
		{"(*Float).Sign", Method, 5, ""},
		{"(*Float).Signbit", Method, 5, ""},
		{"(*Float).Sqrt", Method, 10, ""},
		{"(*Float).String", Method, 5, ""},
		{"(*Float).Sub", Method, 5, ""},
		{"(*Float).Text", Method, 5, ""},
		{"(*Float).Uint64", Method, 5, ""},
		{"(*Float).UnmarshalText", Method, 6, ""},
		{"(*Int).Abs", Method, 0, ""},
		{"(*Int).Add", Method, 0, ""},
		{"(*Int).And", Method, 0, ""},
		{"(*Int).AndNot", Method, 0, ""},
		{"(*Int).Append", Method, 6, ""},
		{"(*Int).AppendText", Method, 24, ""},
		{"(*Int).Binomial", Method, 0, ""},
		{"(*Int).Bit", Method, 0, ""},
		{"(*Int).BitLen", Method, 0, ""},
		{"(*Int).Bits", Method, 0, ""},
		{"(*Int).Bytes", Method, 0, ""},
		{"(*Int).Cmp", Method, 0, ""},
		{"(*Int).CmpAbs", Method, 10, ""},
		{"(*Int).Div", Method, 0, ""},
		{"(*Int).DivMod", Method, 0, ""},
		{"(*Int).Exp", Method, 0, ""},
		{"(*Int).FillBytes", Method, 15, ""},
		{"(*Int).Float64", Method, 21, ""},
		{"(*Int).Format", Method, 0, ""},
		{"(*Int).GCD", Method, 0, ""},
		{"(*Int).GobDecode", Method, 0, ""},
		{"(*Int).GobEncode", Method, 0, ""},
		{"(*Int).Int64", Method, 0, ""},
		{"(*Int).IsInt64", Method, 9, ""},
		{"(*Int).IsUint64", Method, 9, ""},
		{"(*Int).Lsh", Method, 0, ""},
		{"(*Int).MarshalJSON", Method, 1, ""},
		{"(*Int).MarshalText", Method, 3, ""},
		{"(*Int).Mod", Method, 0, ""},
		{"(*Int).ModInverse", Method, 0, ""},
		{"(*Int).ModSqrt", Method, 5, ""},
		{"(*Int).Mul", Method, 0, ""},
		{"(*Int).MulRange", Method, 0, ""},
		{"(*Int).Neg", Method, 0, ""},
		{"(*Int).Not", Method, 0, ""},
		{"(*Int).Or", Method, 0, ""},
		{"(*Int).ProbablyPrime", Method, 0, ""},
		{"(*Int).Quo", Method, 0, ""},
		{"(*Int).QuoRem", Method, 0, ""},
		{"(*Int).Rand", Method, 0, ""},
		{"(*Int).Rem", Method, 0, ""},
		{"(*Int).Rsh", Method, 0, ""},
		{"(*Int).Scan", Method, 0, ""},
		{"(*Int).Set", Method, 0, ""},
		{"(*Int).SetBit", Method, 0, ""},
		{"(*Int).SetBits", Method, 0, ""},
		{"(*Int).SetBytes", Method, 0, ""},
		{"(*Int).SetInt64", Method, 0, ""},
		{"(*Int).SetString", Method, 0, ""},
		{"(*Int).SetUint64", Method, 1, ""},
		{"(*Int).Sign", Method, 0, ""},
		{"(*Int).Sqrt", Method, 8, ""},
		{"(*Int).String", Method, 0, ""},
		{"(*Int).Sub", Method, 0, ""},
		{"(*Int).Text", Method, 6, ""},
		{"(*Int).TrailingZeroBits", Method, 13, ""},
		{"(*Int).Uint64", Method, 1, ""},
		{"(*Int).UnmarshalJSON", Method, 1, ""},
		{"(*Int).UnmarshalText", Method, 3, ""},
		{"(*Int).Xor", Method, 0, ""},
		{"(*Rat).Abs", Method, 0, ""},
		{"(*Rat).Add", Method, 0, ""},
		{"(*Rat).AppendText", Method, 24, ""},
		{"(*Rat).Cmp", Method, 0, ""},
		{"(*Rat).Denom", Method, 0, ""},
		{"(*Rat).Float32", Method, 4, ""},
		{"(*Rat).Float64", Method, 1, ""},
		{"(*Rat).FloatPrec", Method, 22, ""},
		{"(*Rat).FloatString", Method, 0, ""},
		{"(*Rat).GobDecode", Method, 0, ""},
		{"(*Rat).GobEncode", Method, 0, ""},
		{"(*Rat).Inv", Method, 0, ""},
		{"(*Rat).IsInt", Method, 0, ""},
		{"(*Rat).MarshalText", Method, 3, ""},
		{"(*Rat).Mul", Method, 0, ""},
		{"(*Rat).Neg", Method, 0, ""},
		{"(*Rat).Num", Method, 0, ""},
		{"(*Rat).Quo", Method, 0, ""},
		{"(*Rat).RatString", Method, 0, ""},
		{"(*Rat).Scan", Method, 0, ""},
		{"(*Rat).Set", Method, 0, ""},
		{"(*Rat).SetFloat64", Method, 1, ""},
		{"(*Rat).SetFrac", Method, 0, ""},
		{"(*Rat).SetFrac64", Method, 0, ""},
		{"(*Rat).SetInt", Method, 0, ""},
		{"(*Rat).SetInt64", Method, 0, ""},
		{"(*Rat).SetString", Method, 0, ""},
		{"(*Rat).SetUint64", Method, 13, ""},
		{"(*Rat).Sign", Method, 0, ""},
		{"(*Rat).String", Method, 0, ""},
		{"(*Rat).Sub", Method, 0, ""},
		{"(*Rat).UnmarshalText", Method, 3, ""},
		{"(Accuracy).String", Method, 5, ""},
		{"(ErrNaN).Error", Method, 5, ""},
		{"(RoundingMode).String", Method, 5, ""},
		{"Above", Const, 5, ""},
		{"Accuracy", Type, 5, ""},
		{"AwayFromZero", Const, 5, ""},
		{"Below", Const, 5, ""},
		{"ErrNaN", Type, 5, ""},
		{"Exact", Const, 5, ""},
		{"Float", Type, 5, ""},
		{"Int", Type, 0, ""},
		{"Jacobi", Func, 5, "func(x *Int, y *Int) int"},
		{"MaxBase", Const, 0, ""},
		{"MaxExp", Const, 5, ""},
		{"MaxPrec", Const, 5, ""},
		{"MinExp", Const, 5, ""},
		{"NewFloat", Func, 5, "func(x float64) *Float"},
		{"NewInt", Func, 0, "func(x int64) *Int"},
		{"NewRat", Func, 0, "func(a int64, b int64) *Rat"},
		{"ParseFloat", Func, 5, "func(s string, base int, prec uint, mode RoundingMode) (f *Float, b int, err error)"},
		{"Rat", Type, 0, ""},
		{"RoundingMode", Type, 5, ""},
		{"ToNearestAway", Const, 5, ""},
		{"ToNearestEven", Const, 5, ""},
		{"ToNegativeInf", Const, 5, ""},
		{"ToPositiveInf", Const, 5, ""},
		{"ToZero", Const, 5, ""},
		{"Word", Type, 0, ""},
	},
	"math/bits": {
		{"Add", Func, 12, "func(x uint, y uint, carry uint) (sum uint, carryOut uint)"},
		{"Add32", Func, 12, "func(x uint32, y uint32, carry uint32) (sum uint32, carryOut uint32)"},
		{"Add64", Func, 12, "func(x uint64, y uint64, carry uint64) (sum uint64, carryOut uint64)"},
		{"Div", Func, 12, "func(hi uint, lo uint, y uint) (quo uint, rem uint)"},
		{"Div32", Func, 12, "func(hi uint32, lo uint32, y uint32) (quo uint32, rem uint32)"},
		{"Div64", Func, 12, "func(hi uint64, lo uint64, y uint64) (quo uint64, rem uint64)"},
		{"LeadingZeros", Func, 9, "func(x uint) int"},
		{"LeadingZeros16", Func, 9, "func(x uint16) int"},
		{"LeadingZeros32", Func, 9, "func(x uint32) int"},
		{"LeadingZeros64", Func, 9, "func(x uint64) int"},
		{"LeadingZeros8", Func, 9, "func(x uint8) int"},
		{"Len", Func, 9, "func(x uint) int"},
		{"Len16", Func, 9, "func(x uint16) (n int)"},
		{"Len32", Func, 9, "func(x uint32) (n int)"},
		{"Len64", Func, 9, "func(x uint64) (n int)"},
		{"Len8", Func, 9, "func(x uint8) int"},
		{"Mul", Func, 12, "func(x uint, y uint) (hi uint, lo uint)"},
		{"Mul32", Func, 12, "func(x uint32, y uint32) (hi uint32, lo uint32)"},
		{"Mul64", Func, 12, "func(x uint64, y uint64) (hi uint64, lo uint64)"},
		{"OnesCount", Func, 9, "func(x uint) int"},
		{"OnesCount16", Func, 9, "func(x uint16) int"},
		{"OnesCount32", Func, 9, "func(x uint32) int"},
		{"OnesCount64", Func, 9, "func(x uint64) int"},
		{"OnesCount8", Func, 9, "func(x uint8) int"},
		{"Rem", Func, 14, "func(hi uint, lo uint, y uint) uint"},
		{"Rem32", Func, 14, "func(hi uint32, lo uint32, y uint32) uint32"},
		{"Rem64", Func, 14, "func(hi uint64, lo uint64, y uint64) uint64"},
		{"Reverse", Func, 9, "func(x uint) uint"},
		{"Reverse16", Func, 9, "func(x uint16) uint16"},
		{"Reverse32", Func, 9, "func(x uint32) uint32"},
		{"Reverse64", Func, 9, "func(x uint64) uint64"},
		{"Reverse8", Func, 9, "func(x uint8) uint8"},
		{"ReverseBytes", Func, 9, "func(x uint) uint"},
		{"ReverseBytes16", Func, 9, "func(x uint16) uint16"},
		{"ReverseBytes32", Func, 9, "func(x uint32) uint32"},
		{"ReverseBytes64", Func, 9, "func(x uint64) uint64"},
		{"RotateLeft", Func, 9, "func(x uint, k int) uint"},
		{"RotateLeft16", Func, 9, "func(x uint16, k int) uint16"},
		{"RotateLeft32", Func, 9, "func(x uint32, k int) uint32"},
		{"RotateLeft64", Func, 9, "func(x uint64, k int) uint64"},
		{"RotateLeft8", Func, 9, "func(x uint8, k int) uint8"},
		{"Sub", Func, 12, "func(x uint, y uint, borrow uint) (diff uint, borrowOut uint)"},
		{"Sub32", Func, 12, "func(x uint32, y uint32, borrow uint32) (diff uint32, borrowOut uint32)"},
		{"Sub64", Func, 12, "func(x uint64, y uint64, borrow uint64) (diff uint64, borrowOut uint64)"},
		{"TrailingZeros", Func, 9, "func(x uint) int"},
		{"TrailingZeros16", Func, 9, "func(x uint16) int"},
		{"TrailingZeros32", Func, 9, "func(x uint32) int"},
		{"TrailingZeros64", Func, 9, "func(x uint64) int"},
		{"TrailingZeros8", Func, 9, "func(x uint8) int"},
		{"UintSize", Const, 9, ""},
	},
	"math/cmplx": {
		{"Abs", Func, 0, "func(x complex128) float64"},
		{"Acos", Func, 0, "func(x complex128) complex128"},
		{"Acosh", Func, 0, "func(x complex128) complex128"},
		{"Asin", Func, 0, "func(x complex128) complex128"},
		{"Asinh", Func, 0, "func(x complex128) complex128"},
		{"Atan", Func, 0, "func(x complex128) complex128"},
		{"Atanh", Func, 0, "func(x complex128) complex128"},
		{"Conj", Func, 0, "func(x complex128) complex128"},
		{"Cos", Func, 0, "func(x complex128) complex128"},
		{"Cosh", Func, 0, "func(x complex128) complex128"},
		{"Cot", Func, 0, "func(x complex128) complex128"},
		{"Exp", Func, 0, "func(x complex128) complex128"},
		{"Inf", Func, 0, "func() complex128"},
		{"IsInf", Func, 0, "func(x complex128) bool"},
		{"IsNaN", Func, 0, "func(x complex128) bool"},
		{"Log", Func, 0, "func(x complex128) complex128"},
		{"Log10", Func, 0, "func(x complex128) complex128"},
		{"NaN", Func, 0, "func() complex128"},
		{"Phase", Func, 0, "func(x complex128) float64"},
		{"Polar", Func, 0, "func(x complex128) (r float64, θ float64)"},
		{"Pow", Func, 0, "func(x complex128, y complex128) complex128"},
		{"Rect", Func, 0, "func(r float64, θ float64) complex128"},
		{"Sin", Func, 0, "func(x complex128) complex128"},
		{"Sinh", Func, 0, "func(x complex128) complex128"},
		{"Sqrt", Func, 0, "func(x complex128) complex128"},
		{"Tan", Func, 0, "func(x complex128) complex128"},
		{"Tanh", Func, 0, "func(x complex128) complex128"},
	},
	"math/rand": {
		{"(*Rand).ExpFloat64", Method, 0, ""},
		{"(*Rand).Float32", Method, 0, ""},
		{"(*Rand).Float64", Method, 0, ""},
		{"(*Rand).Int", Method, 0, ""},
		{"(*Rand).Int31", Method, 0, ""},
		{"(*Rand).Int31n", Method, 0, ""},
		{"(*Rand).Int63", Method, 0, ""},
		{"(*Rand).Int63n", Method, 0, ""},
		{"(*Rand).Intn", Method, 0, ""},
		{"(*Rand).NormFloat64", Method, 0, ""},
		{"(*Rand).Perm", Method, 0, ""},
		{"(*Rand).Read", Method, 6, ""},
		{"(*Rand).Seed", Method, 0, ""},
		{"(*Rand).Shuffle", Method, 10, ""},
		{"(*Rand).Uint32", Method, 0, ""},
		{"(*Rand).Uint64", Method, 8, ""},
		{"(*Zipf).Uint64", Method, 0, ""},
		{"(Source).Int63", Method, 0, ""},
		{"(Source).Seed", Method, 0, ""},
		{"(Source64).Int63", Method, 8, ""},
		{"(Source64).Seed", Method, 8, ""},
		{"(Source64).Uint64", Method, 8, ""},
		{"ExpFloat64", Func, 0, "func() float64"},
		{"Float32", Func, 0, "func() float32"},
		{"Float64", Func, 0, "func() float64"},
		{"Int", Func, 0, "func() int"},
		{"Int31", Func, 0, "func() int32"},
		{"Int31n", Func, 0, "func(n int32) int32"},
		{"Int63", Func, 0, "func() int64"},
		{"Int63n", Func, 0, "func(n int64) int64"},
		{"Intn", Func, 0, "func(n int) int"},
		{"New", Func, 0, "func(src Source) *Rand"},
		{"NewSource", Func, 0, "func(seed int64) Source"},
		{"NewZipf", Func, 0, "func(r *Rand, s float64, v float64, imax uint64) *Zipf"},
		{"NormFloat64", Func, 0, "func() float64"},
		{"Perm", Func, 0, "func(n int) []int"},
		{"Rand", Type, 0, ""},
		{"Read", Func, 6, "func(p []byte) (n int, err error)"},
		{"Seed", Func, 0, "func(seed int64)"},
		{"Shuffle", Func, 10, "func(n int, swap func(i int, j int))"},
		{"Source", Type, 0, ""},
		{"Source64", Type, 8, ""},
		{"Uint32", Func, 0, "func() uint32"},
		{"Uint64", Func, 8, "func() uint64"},
		{"Zipf", Type, 0, ""},
	},
	"math/rand/v2": {
		{"(*ChaCha8).AppendBinary", Method, 24, ""},
		{"(*ChaCha8).MarshalBinary", Method, 22, ""},
		{"(*ChaCha8).Read", Method, 23, ""},
		{"(*ChaCha8).Seed", Method, 22, ""},
		{"(*ChaCha8).Uint64", Method, 22, ""},
		{"(*ChaCha8).UnmarshalBinary", Method, 22, ""},
		{"(*PCG).AppendBinary", Method, 24, ""},
		{"(*PCG).MarshalBinary", Method, 22, ""},
		{"(*PCG).Seed", Method, 22, ""},
		{"(*PCG).Uint64", Method, 22, ""},
		{"(*PCG).UnmarshalBinary", Method, 22, ""},
		{"(*Rand).ExpFloat64", Method, 22, ""},
		{"(*Rand).Float32", Method, 22, ""},
		{"(*Rand).Float64", Method, 22, ""},
		{"(*Rand).Int", Method, 22, ""},
		{"(*Rand).Int32", Method, 22, ""},
		{"(*Rand).Int32N", Method, 22, ""},
		{"(*Rand).Int64", Method, 22, ""},
		{"(*Rand).Int64N", Method, 22, ""},
		{"(*Rand).IntN", Method, 22, ""},
		{"(*Rand).NormFloat64", Method, 22, ""},
		{"(*Rand).Perm", Method, 22, ""},
		{"(*Rand).Shuffle", Method, 22, ""},
		{"(*Rand).Uint", Method, 23, ""},
		{"(*Rand).Uint32", Method, 22, ""},
		{"(*Rand).Uint32N", Method, 22, ""},
		{"(*Rand).Uint64", Method, 22, ""},
		{"(*Rand).Uint64N", Method, 22, ""},
		{"(*Rand).UintN", Method, 22, ""},
		{"(*Zipf).Uint64", Method, 22, ""},
		{"(Source).Uint64", Method, 22, ""},
		{"ChaCha8", Type, 22, ""},
		{"ExpFloat64", Func, 22, "func() float64"},
		{"Float32", Func, 22, "func() float32"},
		{"Float64", Func, 22, "func() float64"},
		{"Int", Func, 22, "func() int"},
		{"Int32", Func, 22, "func() int32"},
		{"Int32N", Func, 22, "func(n int32) int32"},
		{"Int64", Func, 22, "func() int64"},
		{"Int64N", Func, 22, "func(n int64) int64"},
		{"IntN", Func, 22, "func(n int) int"},
		{"N", Func, 22, "func[Int intType](n Int) Int"},
		{"New", Func, 22, "func(src Source) *Rand"},
		{"NewChaCha8", Func, 22, "func(seed [32]byte) *ChaCha8"},
		{"NewPCG", Func, 22, "func(seed1 uint64, seed2 uint64) *PCG"},
		{"NewZipf", Func, 22, "func(r *Rand, s float64, v float64, imax uint64) *Zipf"},
		{"NormFloat64", Func, 22, "func() float64"},
		{"PCG", Type, 22, ""},
		{"Perm", Func, 22, "func(n int) []int"},
		{"Rand", Type, 22, ""},
		{"Shuffle", Func, 22, "func(n int, swap func(i int, j int))"},
		{"Source", Type, 22, ""},
		{"Uint", Func, 23, "func() uint"},
		{"Uint32", Func, 22, "func() uint32"},
		{"Uint32N", Func, 22, "func(n uint32) uint32"},
		{"Uint64", Func, 22, "func() uint64"},
		{"Uint64N", Func, 22, "func(n uint64) uint64"},
		{"UintN", Func, 22, "func(n uint) uint"},
		{"Zipf", Type, 22, ""},
	},
	"mime": {
		{"(*WordDecoder).Decode", Method, 5, ""},
		{"(*WordDecoder).DecodeHeader", Method, 5, ""},
		{"(WordEncoder).Encode", Method, 5, ""},
		{"AddExtensionType", Func, 0, "func(ext string, typ string) error"},
		{"BEncoding", Const, 5, ""},
		{"ErrInvalidMediaParameter", Var, 9, ""},
		{"ExtensionsByType", Func, 5, "func(typ string) ([]string, error)"},
		{"FormatMediaType", Func, 0, "func(t string, param map[string]string) string"},
		{"ParseMediaType", Func, 0, "func(v string) (mediatype string, params map[string]string, err error)"},
		{"QEncoding", Const, 5, ""},
		{"TypeByExtension", Func, 0, "func(ext string) string"},
		{"WordDecoder", Type, 5, ""},
		{"WordDecoder.CharsetReader", Field, 5, ""},
		{"WordEncoder", Type, 5, ""},
	},
	"mime/multipart": {
		{"(*FileHeader).Open", Method, 0, ""},
		{"(*Form).RemoveAll", Method, 0, ""},
		{"(*Part).Close", Method, 0, ""},
		{"(*Part).FileName", Method, 0, ""},
		{"(*Part).FormName", Method, 0, ""},
		{"(*Part).Read", Method, 0, ""},
		{"(*Reader).NextPart", Method, 0, ""},
		{"(*Reader).NextRawPart", Method, 14, ""},
		{"(*Reader).ReadForm", Method, 0, ""},
		{"(*Writer).Boundary", Method, 0, ""},
		{"(*Writer).Close", Method, 0, ""},
		{"(*Writer).CreateFormField", Method, 0, ""},
		{"(*Writer).CreateFormFile", Method, 0, ""},
		{"(*Writer).CreatePart", Method, 0, ""},
		{"(*Writer).FormDataContentType", Method, 0, ""},
		{"(*Writer).SetBoundary", Method, 1, ""},
		{"(*Writer).WriteField", Method, 0, ""},
		{"(File).Close", Method, 0, ""},
		{"(File).Read", Method, 0, ""},
		{"(File).ReadAt", Method, 0, ""},
		{"(File).Seek", Method, 0, ""},
		{"ErrMessageTooLarge", Var, 9, ""},
		{"File", Type, 0, ""},
		{"FileContentDisposition", Func, 25, "func(fieldname string, filename string) string"},
		{"FileHeader", Type, 0, ""},
		{"FileHeader.Filename", Field, 0, ""},
		{"FileHeader.Header", Field, 0, ""},
		{"FileHeader.Size", Field, 9, ""},
		{"Form", Type, 0, ""},
		{"Form.File", Field, 0, ""},
		{"Form.Value", Field, 0, ""},
		{"NewReader", Func, 0, "func(r io.Reader, boundary string) *Reader"},
		{"NewWriter", Func, 0, "func(w io.Writer) *Writer"},
		{"Part", Type, 0, ""},
		{"Part.Header", Field, 0, ""},
		{"Reader", Type, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"mime/quotedprintable": {
		{"(*Reader).Read", Method, 5, ""},
		{"(*Writer).Close", Method, 5, ""},
		{"(*Writer).Write", Method, 5, ""},
		{"NewReader", Func, 5, "func(r io.Reader) *Reader"},
		{"NewWriter", Func, 5, "func(w io.Writer) *Writer"},
		{"Reader", Type, 5, ""},
		{"Writer", Type, 5, ""},
		{"Writer.Binary", Field, 5, ""},
	},
	"net": {
		{"(*AddrError).Error", Method, 0, ""},
		{"(*AddrError).Temporary", Method, 0, ""},
		{"(*AddrError).Timeout", Method, 0, ""},
		{"(*Buffers).Read", Method, 8, ""},
		{"(*Buffers).WriteTo", Method, 8, ""},
		{"(*DNSConfigError).Error", Method, 0, ""},
		{"(*DNSConfigError).Temporary", Method, 0, ""},
		{"(*DNSConfigError).Timeout", Method, 0, ""},
		{"(*DNSConfigError).Unwrap", Method, 13, ""},
		{"(*DNSError).Error", Method, 0, ""},
		{"(*DNSError).Temporary", Method, 0, ""},
		{"(*DNSError).Timeout", Method, 0, ""},
		{"(*DNSError).Unwrap", Method, 23, ""},
		{"(*Dialer).Dial", Method, 1, ""},
		{"(*Dialer).DialContext", Method, 7, ""},
		{"(*Dialer).DialIP", Method, 26, ""},
		{"(*Dialer).DialTCP", Method, 26, ""},
		{"(*Dialer).DialUDP", Method, 26, ""},
		{"(*Dialer).DialUnix", Method, 26, ""},
		{"(*Dialer).MultipathTCP", Method, 21, ""},
		{"(*Dialer).SetMultipathTCP", Method, 21, ""},
		{"(*IP).UnmarshalText", Method, 2, ""},
		{"(*IPAddr).Network", Method, 0, ""},
		{"(*IPAddr).String", Method, 0, ""},
		{"(*IPConn).Close", Method, 0, ""},
		{"(*IPConn).File", Method, 0, ""},
		{"(*IPConn).LocalAddr", Method, 0, ""},
		{"(*IPConn).Read", Method, 0, ""},
		{"(*IPConn).ReadFrom", Method, 0, ""},
		{"(*IPConn).ReadFromIP", Method, 0, ""},
		{"(*IPConn).ReadMsgIP", Method, 1, ""},
		{"(*IPConn).RemoteAddr", Method, 0, ""},
		{"(*IPConn).SetDeadline", Method, 0, ""},
		{"(*IPConn).SetReadBuffer", Method, 0, ""},
		{"(*IPConn).SetReadDeadline", Method, 0, ""},
		{"(*IPConn).SetWriteBuffer", Method, 0, ""},
		{"(*IPConn).SetWriteDeadline", Method, 0, ""},
		{"(*IPConn).SyscallConn", Method, 9, ""},
		{"(*IPConn).Write", Method, 0, ""},
		{"(*IPConn).WriteMsgIP", Method, 1, ""},
		{"(*IPConn).WriteTo", Method, 0, ""},
		{"(*IPConn).WriteToIP", Method, 0, ""},
		{"(*IPNet).Contains", Method, 0, ""},
		{"(*IPNet).Network", Method, 0, ""},
		{"(*IPNet).String", Method, 0, ""},
		{"(*Interface).Addrs", Method, 0, ""},
		{"(*Interface).MulticastAddrs", Method, 0, ""},
		{"(*ListenConfig).Listen", Method, 11, ""},
		{"(*ListenConfig).ListenPacket", Method, 11, ""},
		{"(*ListenConfig).MultipathTCP", Method, 21, ""},
		{"(*ListenConfig).SetMultipathTCP", Method, 21, ""},
		{"(*OpError).Error", Method, 0, ""},
		{"(*OpError).Temporary", Method, 0, ""},
		{"(*OpError).Timeout", Method, 0, ""},
		{"(*OpError).Unwrap", Method, 13, ""},
		{"(*ParseError).Error", Method, 0, ""},
		{"(*ParseError).Temporary", Method, 17, ""},
		{"(*ParseError).Timeout", Method, 17, ""},
		{"(*Resolver).LookupAddr", Method, 8, ""},
		{"(*Resolver).LookupCNAME", Method, 8, ""},
		{"(*Resolver).LookupHost", Method, 8, ""},
		{"(*Resolver).LookupIP", Method, 15, ""},
		{"(*Resolver).LookupIPAddr", Method, 8, ""},
		{"(*Resolver).LookupMX", Method, 8, ""},
		{"(*Resolver).LookupNS", Method, 8, ""},
		{"(*Resolver).LookupNetIP", Method, 18, ""},
		{"(*Resolver).LookupPort", Method, 8, ""},
		{"(*Resolver).LookupSRV", Method, 8, ""},
		{"(*Resolver).LookupTXT", Method, 8, ""},
		{"(*TCPAddr).AddrPort", Method, 18, ""},
		{"(*TCPAddr).Network", Method, 0, ""},
		{"(*TCPAddr).String", Method, 0, ""},
		{"(*TCPConn).Close", Method, 0, ""},
		{"(*TCPConn).CloseRead", Method, 0, ""},
		{"(*TCPConn).CloseWrite", Method, 0, ""},
		{"(*TCPConn).File", Method, 0, ""},
		{"(*TCPConn).LocalAddr", Method, 0, ""},
		{"(*TCPConn).MultipathTCP", Method, 21, ""},
		{"(*TCPConn).Read", Method, 0, ""},
		{"(*TCPConn).ReadFrom", Method, 0, ""},
		{"(*TCPConn).RemoteAddr", Method, 0, ""},
		{"(*TCPConn).SetDeadline", Method, 0, ""},
		{"(*TCPConn).SetKeepAlive", Method, 0, ""},
		{"(*TCPConn).SetKeepAliveConfig", Method, 23, ""},
		{"(*TCPConn).SetKeepAlivePeriod", Method, 2, ""},
		{"(*TCPConn).SetLinger", Method, 0, ""},
		{"(*TCPConn).SetNoDelay", Method, 0, ""},
		{"(*TCPConn).SetReadBuffer", Method, 0, ""},
		{"(*TCPConn).SetReadDeadline", Method, 0, ""},
		{"(*TCPConn).SetWriteBuffer", Method, 0, ""},
		{"(*TCPConn).SetWriteDeadline", Method, 0, ""},
		{"(*TCPConn).SyscallConn", Method, 9, ""},
		{"(*TCPConn).Write", Method, 0, ""},
		{"(*TCPConn).WriteTo", Method, 22, ""},
		{"(*TCPListener).Accept", Method, 0, ""},
		{"(*TCPListener).AcceptTCP", Method, 0, ""},
		{"(*TCPListener).Addr", Method, 0, ""},
		{"(*TCPListener).Close", Method, 0, ""},
		{"(*TCPListener).File", Method, 0, ""},
		{"(*TCPListener).SetDeadline", Method, 0, ""},
		{"(*TCPListener).SyscallConn", Method, 10, ""},
		{"(*UDPAddr).AddrPort", Method, 18, ""},
		{"(*UDPAddr).Network", Method, 0, ""},
		{"(*UDPAddr).String", Method, 0, ""},
		{"(*UDPConn).Close", Method, 0, ""},
		{"(*UDPConn).File", Method, 0, ""},
		{"(*UDPConn).LocalAddr", Method, 0, ""},
		{"(*UDPConn).Read", Method, 0, ""},
		{"(*UDPConn).ReadFrom", Method, 0, ""},
		{"(*UDPConn).ReadFromUDP", Method, 0, ""},
		{"(*UDPConn).ReadFromUDPAddrPort", Method, 18, ""},
		{"(*UDPConn).ReadMsgUDP", Method, 1, ""},
		{"(*UDPConn).ReadMsgUDPAddrPort", Method, 18, ""},
		{"(*UDPConn).RemoteAddr", Method, 0, ""},
		{"(*UDPConn).SetDeadline", Method, 0, ""},
		{"(*UDPConn).SetReadBuffer", Method, 0, ""},
		{"(*UDPConn).SetReadDeadline", Method, 0, ""},
		{"(*UDPConn).SetWriteBuffer", Method, 0, ""},
		{"(*UDPConn).SetWriteDeadline", Method, 0, ""},
		{"(*UDPConn).SyscallConn", Method, 9, ""},
		{"(*UDPConn).Write", Method, 0, ""},
		{"(*UDPConn).WriteMsgUDP", Method, 1, ""},
		{"(*UDPConn).WriteMsgUDPAddrPort", Method, 18, ""},
		{"(*UDPConn).WriteTo", Method, 0, ""},
		{"(*UDPConn).WriteToUDP", Method, 0, ""},
		{"(*UDPConn).WriteToUDPAddrPort", Method, 18, ""},
		{"(*UnixAddr).Network", Method, 0, ""},
		{"(*UnixAddr).String", Method, 0, ""},
		{"(*UnixConn).Close", Method, 0, ""},
		{"(*UnixConn).CloseRead", Method, 1, ""},
		{"(*UnixConn).CloseWrite", Method, 1, ""},
		{"(*UnixConn).File", Method, 0, ""},
		{"(*UnixConn).LocalAddr", Method, 0, ""},
		{"(*UnixConn).Read", Method, 0, ""},
		{"(*UnixConn).ReadFrom", Method, 0, ""},
		{"(*UnixConn).ReadFromUnix", Method, 0, ""},
		{"(*UnixConn).ReadMsgUnix", Method, 0, ""},
		{"(*UnixConn).RemoteAddr", Method, 0, ""},
		{"(*UnixConn).SetDeadline", Method, 0, ""},
		{"(*UnixConn).SetReadBuffer", Method, 0, ""},
		{"(*UnixConn).SetReadDeadline", Method, 0, ""},
		{"(*UnixConn).SetWriteBuffer", Method, 0, ""},
		{"(*UnixConn).SetWriteDeadline", Method, 0, ""},
		{"(*UnixConn).SyscallConn", Method, 9, ""},
		{"(*UnixConn).Write", Method, 0, ""},
		{"(*UnixConn).WriteMsgUnix", Method, 0, ""},
		{"(*UnixConn).WriteTo", Method, 0, ""},
		{"(*UnixConn).WriteToUnix", Method, 0, ""},
		{"(*UnixListener).Accept", Method, 0, ""},
		{"(*UnixListener).AcceptUnix", Method, 0, ""},
		{"(*UnixListener).Addr", Method, 0, ""},
		{"(*UnixListener).Close", Method, 0, ""},
		{"(*UnixListener).File", Method, 0, ""},
		{"(*UnixListener).SetDeadline", Method, 0, ""},
		{"(*UnixListener).SetUnlinkOnClose", Method, 8, ""},
		{"(*UnixListener).SyscallConn", Method, 10, ""},
		{"(Addr).Network", Method, 0, ""},
		{"(Addr).String", Method, 0, ""},
		{"(Conn).Close", Method, 0, ""},
		{"(Conn).LocalAddr", Method, 0, ""},
		{"(Conn).Read", Method, 0, ""},
		{"(Conn).RemoteAddr", Method, 0, ""},
		{"(Conn).SetDeadline", Method, 0, ""},
		{"(Conn).SetReadDeadline", Method, 0, ""},
		{"(Conn).SetWriteDeadline", Method, 0, ""},
		{"(Conn).Write", Method, 0, ""},
		{"(Error).Error", Method, 0, ""},
		{"(Error).Temporary", Method, 0, ""},
		{"(Error).Timeout", Method, 0, ""},
		{"(Flags).String", Method, 0, ""},
		{"(HardwareAddr).String", Method, 0, ""},
		{"(IP).AppendText", Method, 24, ""},
		{"(IP).DefaultMask", Method, 0, ""},
		{"(IP).Equal", Method, 0, ""},
		{"(IP).IsGlobalUnicast", Method, 0, ""},
		{"(IP).IsInterfaceLocalMulticast", Method, 0, ""},
		{"(IP).IsLinkLocalMulticast", Method, 0, ""},
		{"(IP).IsLinkLocalUnicast", Method, 0, ""},
		{"(IP).IsLoopback", Method, 0, ""},
		{"(IP).IsMulticast", Method, 0, ""},
		{"(IP).IsPrivate", Method, 17, ""},
		{"(IP).IsUnspecified", Method, 0, ""},
		{"(IP).MarshalText", Method, 2, ""},
		{"(IP).Mask", Method, 0, ""},
		{"(IP).String", Method, 0, ""},
		{"(IP).To16", Method, 0, ""},
		{"(IP).To4", Method, 0, ""},
		{"(IPMask).Size", Method, 0, ""},
		{"(IPMask).String", Method, 0, ""},
		{"(InvalidAddrError).Error", Method, 0, ""},
		{"(InvalidAddrError).Temporary", Method, 0, ""},
		{"(InvalidAddrError).Timeout", Method, 0, ""},
		{"(Listener).Accept", Method, 0, ""},
		{"(Listener).Addr", Method, 0, ""},
		{"(Listener).Close", Method, 0, ""},
		{"(PacketConn).Close", Method, 0, ""},
		{"(PacketConn).LocalAddr", Method, 0, ""},
		{"(PacketConn).ReadFrom", Method, 0, ""},
		{"(PacketConn).SetDeadline", Method, 0, ""},
		{"(PacketConn).SetReadDeadline", Method, 0, ""},
		{"(PacketConn).SetWriteDeadline", Method, 0, ""},
		{"(PacketConn).WriteTo", Method, 0, ""},
		{"(UnknownNetworkError).Error", Method, 0, ""},
		{"(UnknownNetworkError).Temporary", Method, 0, ""},
		{"(UnknownNetworkError).Timeout", Method, 0, ""},
		{"Addr", Type, 0, ""},
		{"AddrError", Type, 0, ""},
		{"AddrError.Addr", Field, 0, ""},
		{"AddrError.Err", Field, 0, ""},
		{"Buffers", Type, 8, ""},
		{"CIDRMask", Func, 0, "func(ones int, bits int) IPMask"},
		{"Conn", Type, 0, ""},
		{"DNSConfigError", Type, 0, ""},
		{"DNSConfigError.Err", Field, 0, ""},
		{"DNSError", Type, 0, ""},
		{"DNSError.Err", Field, 0, ""},
		{"DNSError.IsNotFound", Field, 13, ""},
		{"DNSError.IsTemporary", Field, 6, ""},
		{"DNSError.IsTimeout", Field, 0, ""},
		{"DNSError.Name", Field, 0, ""},
		{"DNSError.Server", Field, 0, ""},
		{"DNSError.UnwrapErr", Field, 23, ""},
		{"DefaultResolver", Var, 8, ""},
		{"Dial", Func, 0, "func(network string, address string) (Conn, error)"},
		{"DialIP", Func, 0, "func(network string, laddr *IPAddr, raddr *IPAddr) (*IPConn, error)"},
		{"DialTCP", Func, 0, "func(network string, laddr *TCPAddr, raddr *TCPAddr) (*TCPConn, error)"},
		{"DialTimeout", Func, 0, "func(network string, address string, timeout time.Duration) (Conn, error)"},
		{"DialUDP", Func, 0, "func(network string, laddr *UDPAddr, raddr *UDPAddr) (*UDPConn, error)"},
		{"DialUnix", Func, 0, "func(network string, laddr *UnixAddr, raddr *UnixAddr) (*UnixConn, error)"},
		{"Dialer", Type, 1, ""},
		{"Dialer.Cancel", Field, 6, ""},
		{"Dialer.Control", Field, 11, ""},
		{"Dialer.ControlContext", Field, 20, ""},
		{"Dialer.Deadline", Field, 1, ""},
		{"Dialer.DualStack", Field, 2, ""},
		{"Dialer.FallbackDelay", Field, 5, ""},
		{"Dialer.KeepAlive", Field, 3, ""},
		{"Dialer.KeepAliveConfig", Field, 23, ""},
		{"Dialer.LocalAddr", Field, 1, ""},
		{"Dialer.Resolver", Field, 8, ""},
		{"Dialer.Timeout", Field, 1, ""},
		{"ErrClosed", Var, 16, ""},
		{"ErrWriteToConnected", Var, 0, ""},
		{"Error", Type, 0, ""},
		{"FileConn", Func, 0, "func(f *os.File) (c Conn, err error)"},
		{"FileListener", Func, 0, "func(f *os.File) (ln Listener, err error)"},
		{"FilePacketConn", Func, 0, "func(f *os.File) (c PacketConn, err error)"},
		{"FlagBroadcast", Const, 0, ""},
		{"FlagLoopback", Const, 0, ""},
		{"FlagMulticast", Const, 0, ""},
		{"FlagPointToPoint", Const, 0, ""},
		{"FlagRunning", Const, 20, ""},
		{"FlagUp", Const, 0, ""},
		{"Flags", Type, 0, ""},
		{"HardwareAddr", Type, 0, ""},
		{"IP", Type, 0, ""},
		{"IPAddr", Type, 0, ""},
		{"IPAddr.IP", Field, 0, ""},
		{"IPAddr.Zone", Field, 1, ""},
		{"IPConn", Type, 0, ""},
		{"IPMask", Type, 0, ""},
		{"IPNet", Type, 0, ""},
		{"IPNet.IP", Field, 0, ""},
		{"IPNet.Mask", Field, 0, ""},
		{"IPv4", Func, 0, "func(a byte, b byte, c byte, d byte) IP"},
		{"IPv4Mask", Func, 0, "func(a byte, b byte, c byte, d byte) IPMask"},
		{"IPv4allrouter", Var, 0, ""},
		{"IPv4allsys", Var, 0, ""},
		{"IPv4bcast", Var, 0, ""},
		{"IPv4len", Const, 0, ""},
		{"IPv4zero", Var, 0, ""},
		{"IPv6interfacelocalallnodes", Var, 0, ""},
		{"IPv6len", Const, 0, ""},
		{"IPv6linklocalallnodes", Var, 0, ""},
		{"IPv6linklocalallrouters", Var, 0, ""},
		{"IPv6loopback", Var, 0, ""},
		{"IPv6unspecified", Var, 0, ""},
		{"IPv6zero", Var, 0, ""},
		{"Interface", Type, 0, ""},
		{"Interface.Flags", Field, 0, ""},
		{"Interface.HardwareAddr", Field, 0, ""},
		{"Interface.Index", Field, 0, ""},
		{"Interface.MTU", Field, 0, ""},
		{"Interface.Name", Field, 0, ""},
		{"InterfaceAddrs", Func, 0, "func() ([]Addr, error)"},
		{"InterfaceByIndex", Func, 0, "func(index int) (*Interface, error)"},
		{"InterfaceByName", Func, 0, "func(name string) (*Interface, error)"},
		{"Interfaces", Func, 0, "func() ([]Interface, error)"},
		{"InvalidAddrError", Type, 0, ""},
		{"JoinHostPort", Func, 0, "func(host string, port string) string"},
		{"KeepAliveConfig", Type, 23, ""},
		{"KeepAliveConfig.Count", Field, 23, ""},
		{"KeepAliveConfig.Enable", Field, 23, ""},
		{"KeepAliveConfig.Idle", Field, 23, ""},
		{"KeepAliveConfig.Interval", Field, 23, ""},
		{"Listen", Func, 0, "func(network string, address string) (Listener, error)"},
		{"ListenConfig", Type, 11, ""},
		{"ListenConfig.Control", Field, 11, ""},
		{"ListenConfig.KeepAlive", Field, 13, ""},
		{"ListenConfig.KeepAliveConfig", Field, 23, ""},
		{"ListenIP", Func, 0, "func(network string, laddr *IPAddr) (*IPConn, error)"},
		{"ListenMulticastUDP", Func, 0, "func(network string, ifi *Interface, gaddr *UDPAddr) (*UDPConn, error)"},
		{"ListenPacket", Func, 0, "func(network string, address string) (PacketConn, error)"},
		{"ListenTCP", Func, 0, "func(network string, laddr *TCPAddr) (*TCPListener, error)"},
		{"ListenUDP", Func, 0, "func(network string, laddr *UDPAddr) (*UDPConn, error)"},
		{"ListenUnix", Func, 0, "func(network string, laddr *UnixAddr) (*UnixListener, error)"},
		{"ListenUnixgram", Func, 0, "func(network string, laddr *UnixAddr) (*UnixConn, error)"},
		{"Listener", Type, 0, ""},
		{"LookupAddr", Func, 0, "func(addr string) (names []string, err error)"},
		{"LookupCNAME", Func, 0, "func(host string) (cname string, err error)"},
		{"LookupHost", Func, 0, "func(host string) (addrs []string, err error)"},
		{"LookupIP", Func, 0, "func(host string) ([]IP, error)"},
		{"LookupMX", Func, 0, "func(name string) ([]*MX, error)"},
		{"LookupNS", Func, 1, "func(name string) ([]*NS, error)"},
		{"LookupPort", Func, 0, "func(network string, service string) (port int, err error)"},
		{"LookupSRV", Func, 0, "func(service string, proto string, name string) (cname string, addrs []*SRV, err error)"},
		{"LookupTXT", Func, 0, "func(name string) ([]string, error)"},
		{"MX", Type, 0, ""},
		{"MX.Host", Field, 0, ""},
		{"MX.Pref", Field, 0, ""},
		{"NS", Type, 1, ""},
		{"NS.Host", Field, 1, ""},
		{"OpError", Type, 0, ""},
		{"OpError.Addr", Field, 0, ""},
		{"OpError.Err", Field, 0, ""},
		{"OpError.Net", Field, 0, ""},
		{"OpError.Op", Field, 0, ""},
		{"OpError.Source", Field, 5, ""},
		{"PacketConn", Type, 0, ""},
		{"ParseCIDR", Func, 0, "func(s string) (IP, *IPNet, error)"},
		{"ParseError", Type, 0, ""},
		{"ParseError.Text", Field, 0, ""},
		{"ParseError.Type", Field, 0, ""},
		{"ParseIP", Func, 0, "func(s string) IP"},
		{"ParseMAC", Func, 0, "func(s string) (hw HardwareAddr, err error)"},
		{"Pipe", Func, 0, "func() (Conn, Conn)"},
		{"ResolveIPAddr", Func, 0, "func(network string, address string) (*IPAddr, error)"},
		{"ResolveTCPAddr", Func, 0, "func(network string, address string) (*TCPAddr, error)"},
		{"ResolveUDPAddr", Func, 0, "func(network string, address string) (*UDPAddr, error)"},
		{"ResolveUnixAddr", Func, 0, "func(network string, address string) (*UnixAddr, error)"},
		{"Resolver", Type, 8, ""},
		{"Resolver.Dial", Field, 9, ""},
		{"Resolver.PreferGo", Field, 8, ""},
		{"Resolver.StrictErrors", Field, 9, ""},
		{"SRV", Type, 0, ""},
		{"SRV.Port", Field, 0, ""},
		{"SRV.Priority", Field, 0, ""},
		{"SRV.Target", Field, 0, ""},
		{"SRV.Weight", Field, 0, ""},
		{"SplitHostPort", Func, 0, "func(hostport string) (host string, port string, err error)"},
		{"TCPAddr", Type, 0, ""},
		{"TCPAddr.IP", Field, 0, ""},
		{"TCPAddr.Port", Field, 0, ""},
		{"TCPAddr.Zone", Field, 1, ""},
		{"TCPAddrFromAddrPort", Func, 18, "func(addr netip.AddrPort) *TCPAddr"},
		{"TCPConn", Type, 0, ""},
		{"TCPListener", Type, 0, ""},
		{"UDPAddr", Type, 0, ""},
		{"UDPAddr.IP", Field, 0, ""},
		{"UDPAddr.Port", Field, 0, ""},
		{"UDPAddr.Zone", Field, 1, ""},
		{"UDPAddrFromAddrPort", Func, 18, "func(addr netip.AddrPort) *UDPAddr"},
		{"UDPConn", Type, 0, ""},
		{"UnixAddr", Type, 0, ""},
		{"UnixAddr.Name", Field, 0, ""},
		{"UnixAddr.Net", Field, 0, ""},
		{"UnixConn", Type, 0, ""},
		{"UnixListener", Type, 0, ""},
		{"UnknownNetworkError", Type, 0, ""},
	},
	"net/http": {
		{"(*Client).CloseIdleConnections", Method, 12, ""},
		{"(*Client).Do", Method, 0, ""},
		{"(*Client).Get", Method, 0, ""},
		{"(*Client).Head", Method, 0, ""},
		{"(*Client).Post", Method, 0, ""},
		{"(*Client).PostForm", Method, 0, ""},
		{"(*ClientConn).Available", Method, 26, ""},
		{"(*ClientConn).Close", Method, 26, ""},
		{"(*ClientConn).Err", Method, 26, ""},
		{"(*ClientConn).InFlight", Method, 26, ""},
		{"(*ClientConn).Release", Method, 26, ""},
		{"(*ClientConn).Reserve", Method, 26, ""},
		{"(*ClientConn).RoundTrip", Method, 26, ""},
		{"(*ClientConn).SetStateHook", Method, 26, ""},
		{"(*Cookie).String", Method, 0, ""},
		{"(*Cookie).Valid", Method, 18, ""},
		{"(*CrossOriginProtection).AddInsecureBypassPattern", Method, 25, ""},
		{"(*CrossOriginProtection).AddTrustedOrigin", Method, 25, ""},
		{"(*CrossOriginProtection).Check", Method, 25, ""},
		{"(*CrossOriginProtection).Handler", Method, 25, ""},
		{"(*CrossOriginProtection).SetDenyHandler", Method, 25, ""},
		{"(*MaxBytesError).Error", Method, 19, ""},
		{"(*ProtocolError).Error", Method, 0, ""},
		{"(*ProtocolError).Is", Method, 21, ""},
		{"(*Protocols).SetHTTP1", Method, 24, ""},
		{"(*Protocols).SetHTTP2", Method, 24, ""},
		{"(*Protocols).SetUnencryptedHTTP2", Method, 24, ""},
		{"(*Request).AddCookie", Method, 0, ""},
		{"(*Request).BasicAuth", Method, 4, ""},
		{"(*Request).Clone", Method, 13, ""},
		{"(*Request).Context", Method, 7, ""},
		{"(*Request).Cookie", Method, 0, ""},
		{"(*Request).Cookies", Method, 0, ""},
		{"(*Request).CookiesNamed", Method, 23, ""},
		{"(*Request).FormFile", Method, 0, ""},
		{"(*Request).FormValue", Method, 0, ""},
		{"(*Request).MultipartReader", Method, 0, ""},
		{"(*Request).ParseForm", Method, 0, ""},
		{"(*Request).ParseMultipartForm", Method, 0, ""},
		{"(*Request).PathValue", Method, 22, ""},
		{"(*Request).PostFormValue", Method, 1, ""},
		{"(*Request).ProtoAtLeast", Method, 0, ""},
		{"(*Request).Referer", Method, 0, ""},
		{"(*Request).SetBasicAuth", Method, 0, ""},
		{"(*Request).SetPathValue", Method, 22, ""},
		{"(*Request).UserAgent", Method, 0, ""},
		{"(*Request).WithContext", Method, 7, ""},
		{"(*Request).Write", Method, 0, ""},
		{"(*Request).WriteProxy", Method, 0, ""},
		{"(*Response).Cookies", Method, 0, ""},
		{"(*Response).Location", Method, 0, ""},
		{"(*Response).ProtoAtLeast", Method, 0, ""},
		{"(*Response).Write", Method, 0, ""},
		{"(*ResponseController).EnableFullDuplex", Method, 21, ""},
		{"(*ResponseController).Flush", Method, 20, ""},
		{"(*ResponseController).Hijack", Method, 20, ""},
		{"(*ResponseController).SetReadDeadline", Method, 20, ""},
		{"(*ResponseController).SetWriteDeadline", Method, 20, ""},
		{"(*ServeMux).Handle", Method, 0, ""},
		{"(*ServeMux).HandleFunc", Method, 0, ""},
		{"(*ServeMux).Handler", Method, 1, ""},
		{"(*ServeMux).ServeHTTP", Method, 0, ""},
		{"(*Server).Close", Method, 8, ""},
		{"(*Server).ListenAndServe", Method, 0, ""},
		{"(*Server).ListenAndServeTLS", Method, 0, ""},
		{"(*Server).RegisterOnShutdown", Method, 9, ""},
		{"(*Server).Serve", Method, 0, ""},
		{"(*Server).ServeTLS", Method, 9, ""},
		{"(*Server).SetKeepAlivesEnabled", Method, 3, ""},
		{"(*Server).Shutdown", Method, 8, ""},
		{"(*Transport).CancelRequest", Method, 1, ""},
		{"(*Transport).Clone", Method, 13, ""},
		{"(*Transport).CloseIdleConnections", Method, 0, ""},
		{"(*Transport).NewClientConn", Method, 26, ""},
		{"(*Transport).RegisterProtocol", Method, 0, ""},
		{"(*Transport).RoundTrip", Method, 0, ""},
		{"(CloseNotifier).CloseNotify", Method, 1, ""},
		{"(ConnState).String", Method, 3, ""},
		{"(CookieJar).Cookies", Method, 0, ""},
		{"(CookieJar).SetCookies", Method, 0, ""},
		{"(Dir).Open", Method, 0, ""},
		{"(File).Close", Method, 0, ""},
		{"(File).Read", Method, 0, ""},
		{"(File).Readdir", Method, 0, ""},
		{"(File).Seek", Method, 0, ""},
		{"(File).Stat", Method, 0, ""},
		{"(FileSystem).Open", Method, 0, ""},
		{"(Flusher).Flush", Method, 0, ""},
		{"(Handler).ServeHTTP", Method, 0, ""},
		{"(HandlerFunc).ServeHTTP", Method, 0, ""},
		{"(Header).Add", Method, 0, ""},
		{"(Header).Clone", Method, 13, ""},
		{"(Header).Del", Method, 0, ""},
		{"(Header).Get", Method, 0, ""},
		{"(Header).Set", Method, 0, ""},
		{"(Header).Values", Method, 14, ""},
		{"(Header).Write", Method, 0, ""},
		{"(Header).WriteSubset", Method, 0, ""},
		{"(Hijacker).Hijack", Method, 0, ""},
		{"(Protocols).HTTP1", Method, 24, ""},
		{"(Protocols).HTTP2", Method, 24, ""},
		{"(Protocols).String", Method, 24, ""},
		{"(Protocols).UnencryptedHTTP2", Method, 24, ""},
		{"(Pusher).Push", Method, 8, ""},
		{"(ResponseWriter).Header", Method, 0, ""},
		{"(ResponseWriter).Write", Method, 0, ""},
		{"(ResponseWriter).WriteHeader", Method, 0, ""},
		{"(RoundTripper).RoundTrip", Method, 0, ""},
		{"AllowQuerySemicolons", Func, 17, "func(h Handler) Handler"},
		{"CanonicalHeaderKey", Func, 0, "func(s string) string"},
		{"Client", Type, 0, ""},
		{"Client.CheckRedirect", Field, 0, ""},
		{"Client.Jar", Field, 0, ""},
		{"Client.Timeout", Field, 3, ""},
		{"Client.Transport", Field, 0, ""},
		{"ClientConn", Type, 26, ""},
		{"CloseNotifier", Type, 1, ""},
		{"ConnState", Type, 3, ""},
		{"Cookie", Type, 0, ""},
		{"Cookie.Domain", Field, 0, ""},
		{"Cookie.Expires", Field, 0, ""},
		{"Cookie.HttpOnly", Field, 0, ""},
		{"Cookie.MaxAge", Field, 0, ""},
		{"Cookie.Name", Field, 0, ""},
		{"Cookie.Partitioned", Field, 23, ""},
		{"Cookie.Path", Field, 0, ""},
		{"Cookie.Quoted", Field, 23, ""},
		{"Cookie.Raw", Field, 0, ""},
		{"Cookie.RawExpires", Field, 0, ""},
		{"Cookie.SameSite", Field, 11, ""},
		{"Cookie.Secure", Field, 0, ""},
		{"Cookie.Unparsed", Field, 0, ""},
		{"Cookie.Value", Field, 0, ""},
		{"CookieJar", Type, 0, ""},
		{"CrossOriginProtection", Type, 25, ""},
		{"DefaultClient", Var, 0, ""},
		{"DefaultMaxHeaderBytes", Const, 0, ""},
		{"DefaultMaxIdleConnsPerHost", Const, 0, ""},
		{"DefaultServeMux", Var, 0, ""},
		{"DefaultTransport", Var, 0, ""},
		{"DetectContentType", Func, 0, "func(data []byte) string"},
		{"Dir", Type, 0, ""},
		{"ErrAbortHandler", Var, 8, ""},
		{"ErrBodyNotAllowed", Var, 0, ""},
		{"ErrBodyReadAfterClose", Var, 0, ""},
		{"ErrContentLength", Var, 0, ""},
		{"ErrHandlerTimeout", Var, 0, ""},
		{"ErrHeaderTooLong", Var, 0, ""},
		{"ErrHijacked", Var, 0, ""},
		{"ErrLineTooLong", Var, 0, ""},
		{"ErrMissingBoundary", Var, 0, ""},
		{"ErrMissingContentLength", Var, 0, ""},
		{"ErrMissingFile", Var, 0, ""},
		{"ErrNoCookie", Var, 0, ""},
		{"ErrNoLocation", Var, 0, ""},
		{"ErrNotMultipart", Var, 0, ""},
		{"ErrNotSupported", Var, 0, ""},
		{"ErrSchemeMismatch", Var, 21, ""},
		{"ErrServerClosed", Var, 8, ""},
		{"ErrShortBody", Var, 0, ""},
		{"ErrSkipAltProtocol", Var, 6, ""},
		{"ErrUnexpectedTrailer", Var, 0, ""},
		{"ErrUseLastResponse", Var, 7, ""},
		{"ErrWriteAfterFlush", Var, 0, ""},
		{"Error", Func, 0, "func(w ResponseWriter, error string, code int)"},
		{"FS", Func, 16, "func(fsys fs.FS) FileSystem"},
		{"File", Type, 0, ""},
		{"FileServer", Func, 0, "func(root FileSystem) Handler"},
		{"FileServerFS", Func, 22, "func(root fs.FS) Handler"},
		{"FileSystem", Type, 0, ""},
		{"Flusher", Type, 0, ""},
		{"Get", Func, 0, "func(url string) (resp *Response, err error)"},
		{"HTTP2Config", Type, 24, ""},
		{"HTTP2Config.CountError", Field, 24, ""},
		{"HTTP2Config.MaxConcurrentStreams", Field, 24, ""},
		{"HTTP2Config.MaxDecoderHeaderTableSize", Field, 24, ""},
		{"HTTP2Config.MaxEncoderHeaderTableSize", Field, 24, ""},
		{"HTTP2Config.MaxReadFrameSize", Field, 24, ""},
		{"HTTP2Config.MaxReceiveBufferPerConnection", Field, 24, ""},
		{"HTTP2Config.MaxReceiveBufferPerStream", Field, 24, ""},
		{"HTTP2Config.PermitProhibitedCipherSuites", Field, 24, ""},
		{"HTTP2Config.PingTimeout", Field, 24, ""},
		{"HTTP2Config.SendPingTimeout", Field, 24, ""},
		{"HTTP2Config.StrictMaxConcurrentRequests", Field, 26, ""},
		{"HTTP2Config.WriteByteTimeout", Field, 24, ""},
		{"Handle", Func, 0, "func(pattern string, handler Handler)"},
		{"HandleFunc", Func, 0, "func(pattern string, handler func(ResponseWriter, *Request))"},
		{"Handler", Type, 0, ""},
		{"HandlerFunc", Type, 0, ""},
		{"Head", Func, 0, "func(url string) (resp *Response, err error)"},
		{"Header", Type, 0, ""},
		{"Hijacker", Type, 0, ""},
		{"ListenAndServe", Func, 0, "func(addr string, handler Handler) error"},
		{"ListenAndServeTLS", Func, 0, "func(addr string, certFile string, keyFile string, handler Handler) error"},
		{"LocalAddrContextKey", Var, 7, ""},
		{"MaxBytesError", Type, 19, ""},
		{"MaxBytesError.Limit", Field, 19, ""},
		{"MaxBytesHandler", Func, 18, "func(h Handler, n int64) Handler"},
		{"MaxBytesReader", Func, 0, "func(w ResponseWriter, r io.ReadCloser, n int64) io.ReadCloser"},
		{"MethodConnect", Const, 6, ""},
		{"MethodDelete", Const, 6, ""},
		{"MethodGet", Const, 6, ""},
		{"MethodHead", Const, 6, ""},
		{"MethodOptions", Const, 6, ""},
		{"MethodPatch", Const, 6, ""},
		{"MethodPost", Const, 6, ""},
		{"MethodPut", Const, 6, ""},
		{"MethodTrace", Const, 6, ""},
		{"NewCrossOriginProtection", Func, 25, "func() *CrossOriginProtection"},
		{"NewFileTransport", Func, 0, "func(fs FileSystem) RoundTripper"},
		{"NewFileTransportFS", Func, 22, "func(fsys fs.FS) RoundTripper"},
		{"NewRequest", Func, 0, "func(method string, url string, body io.Reader) (*Request, error)"},
		{"NewRequestWithContext", Func, 13, "func(ctx context.Context, method string, url string, body io.Reader) (*Request, error)"},
		{"NewResponseController", Func, 20, "func(rw ResponseWriter) *ResponseController"},
		{"NewServeMux", Func, 0, "func() *ServeMux"},
		{"NoBody", Var, 8, ""},
		{"NotFound", Func, 0, "func(w ResponseWriter, r *Request)"},
		{"NotFoundHandler", Func, 0, "func() Handler"},
		{"ParseCookie", Func, 23, "func(line string) ([]*Cookie, error)"},
		{"ParseHTTPVersion", Func, 0, "func(vers string) (major int, minor int, ok bool)"},
		{"ParseSetCookie", Func, 23, "func(line string) (*Cookie, error)"},
		{"ParseTime", Func, 1, "func(text string) (t time.Time, err error)"},
		{"Post", Func, 0, "func(url string, contentType string, body io.Reader) (resp *Response, err error)"},
		{"PostForm", Func, 0, "func(url string, data url.Values) (resp *Response, err error)"},
		{"ProtocolError", Type, 0, ""},
		{"ProtocolError.ErrorString", Field, 0, ""},
		{"Protocols", Type, 24, ""},
		{"ProxyFromEnvironment", Func, 0, "func(req *Request) (*url.URL, error)"},
		{"ProxyURL", Func, 0, "func(fixedURL *url.URL) func(*Request) (*url.URL, error)"},
		{"PushOptions", Type, 8, ""},
		{"PushOptions.Header", Field, 8, ""},
		{"PushOptions.Method", Field, 8, ""},
		{"Pusher", Type, 8, ""},
		{"ReadRequest", Func, 0, "func(b *bufio.Reader) (*Request, error)"},
		{"ReadResponse", Func, 0, "func(r *bufio.Reader, req *Request) (*Response, error)"},
		{"Redirect", Func, 0, "func(w ResponseWriter, r *Request, url string, code int)"},
		{"RedirectHandler", Func, 0, "func(url string, code int) Handler"},
		{"Request", Type, 0, ""},
		{"Request.Body", Field, 0, ""},
		{"Request.Cancel", Field, 5, ""},
		{"Request.Close", Field, 0, ""},
		{"Request.ContentLength", Field, 0, ""},
		{"Request.Form", Field, 0, ""},
		{"Request.GetBody", Field, 8, ""},
		{"Request.Header", Field, 0, ""},
		{"Request.Host", Field, 0, ""},
		{"Request.Method", Field, 0, ""},
		{"Request.MultipartForm", Field, 0, ""},
		{"Request.Pattern", Field, 23, ""},
		{"Request.PostForm", Field, 1, ""},
		{"Request.Proto", Field, 0, ""},
		{"Request.ProtoMajor", Field, 0, ""},
		{"Request.ProtoMinor", Field, 0, ""},
		{"Request.RemoteAddr", Field, 0, ""},
		{"Request.RequestURI", Field, 0, ""},
		{"Request.Response", Field, 7, ""},
		{"Request.TLS", Field, 0, ""},
		{"Request.Trailer", Field, 0, ""},
		{"Request.TransferEncoding", Field, 0, ""},
		{"Request.URL", Field, 0, ""},
		{"Response", Type, 0, ""},
		{"Response.Body", Field, 0, ""},
		{"Response.Close", Field, 0, ""},
		{"Response.ContentLength", Field, 0, ""},
		{"Response.Header", Field, 0, ""},
		{"Response.Proto", Field, 0, ""},
		{"Response.ProtoMajor", Field, 0, ""},
		{"Response.ProtoMinor", Field, 0, ""},
		{"Response.Request", Field, 0, ""},
		{"Response.Status", Field, 0, ""},
		{"Response.StatusCode", Field, 0, ""},
		{"Response.TLS", Field, 3, ""},
		{"Response.Trailer", Field, 0, ""},
		{"Response.TransferEncoding", Field, 0, ""},
		{"Response.Uncompressed", Field, 7, ""},
		{"ResponseController", Type, 20, ""},
		{"ResponseWriter", Type, 0, ""},
		{"RoundTripper", Type, 0, ""},
		{"SameSite", Type, 11, ""},
		{"SameSiteDefaultMode", Const, 11, ""},
		{"SameSiteLaxMode", Const, 11, ""},
		{"SameSiteNoneMode", Const, 13, ""},
		{"SameSiteStrictMode", Const, 11, ""},
		{"Serve", Func, 0, "func(l net.Listener, handler Handler) error"},
		{"ServeContent", Func, 0, "func(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker)"},
		{"ServeFile", Func, 0, "func(w ResponseWriter, r *Request, name string)"},
		{"ServeFileFS", Func, 22, "func(w ResponseWriter, r *Request, fsys fs.FS, name string)"},
		{"ServeMux", Type, 0, ""},
		{"ServeTLS", Func, 9, "func(l net.Listener, handler Handler, certFile string, keyFile string) error"},
		{"Server", Type, 0, ""},
		{"Server.Addr", Field, 0, ""},
		{"Server.BaseContext", Field, 13, ""},
		{"Server.ConnContext", Field, 13, ""},
		{"Server.ConnState", Field, 3, ""},
		{"Server.DisableGeneralOptionsHandler", Field, 20, ""},
		{"Server.ErrorLog", Field, 3, ""},
		{"Server.HTTP2", Field, 24, ""},
		{"Server.Handler", Field, 0, ""},
		{"Server.IdleTimeout", Field, 8, ""},
		{"Server.MaxHeaderBytes", Field, 0, ""},
		{"Server.Protocols", Field, 24, ""},
		{"Server.ReadHeaderTimeout", Field, 8, ""},
		{"Server.ReadTimeout", Field, 0, ""},
		{"Server.TLSConfig", Field, 0, ""},
		{"Server.TLSNextProto", Field, 1, ""},
		{"Server.WriteTimeout", Field, 0, ""},
		{"ServerContextKey", Var, 7, ""},
		{"SetCookie", Func, 0, "func(w ResponseWriter, cookie *Cookie)"},
		{"StateActive", Const, 3, ""},
		{"StateClosed", Const, 3, ""},
		{"StateHijacked", Const, 3, ""},
		{"StateIdle", Const, 3, ""},
		{"StateNew", Const, 3, ""},
		{"StatusAccepted", Const, 0, ""},
		{"StatusAlreadyReported", Const, 7, ""},
		{"StatusBadGateway", Const, 0, ""},
		{"StatusBadRequest", Const, 0, ""},
		{"StatusConflict", Const, 0, ""},
		{"StatusContinue", Const, 0, ""},
		{"StatusCreated", Const, 0, ""},
		{"StatusEarlyHints", Const, 13, ""},
		{"StatusExpectationFailed", Const, 0, ""},
		{"StatusFailedDependency", Const, 7, ""},
		{"StatusForbidden", Const, 0, ""},
		{"StatusFound", Const, 0, ""},
		{"StatusGatewayTimeout", Const, 0, ""},
		{"StatusGone", Const, 0, ""},
		{"StatusHTTPVersionNotSupported", Const, 0, ""},
		{"StatusIMUsed", Const, 7, ""},
		{"StatusInsufficientStorage", Const, 7, ""},
		{"StatusInternalServerError", Const, 0, ""},
		{"StatusLengthRequired", Const, 0, ""},
		{"StatusLocked", Const, 7, ""},
		{"StatusLoopDetected", Const, 7, ""},
		{"StatusMethodNotAllowed", Const, 0, ""},
		{"StatusMisdirectedRequest", Const, 11, ""},
		{"StatusMovedPermanently", Const, 0, ""},
		{"StatusMultiStatus", Const, 7, ""},
		{"StatusMultipleChoices", Const, 0, ""},
		{"StatusNetworkAuthenticationRequired", Const, 6, ""},
		{"StatusNoContent", Const, 0, ""},
		{"StatusNonAuthoritativeInfo", Const, 0, ""},
		{"StatusNotAcceptable", Const, 0, ""},
		{"StatusNotExtended", Const, 7, ""},
		{"StatusNotFound", Const, 0, ""},
		{"StatusNotImplemented", Const, 0, ""},
		{"StatusNotModified", Const, 0, ""},
		{"StatusOK", Const, 0, ""},
		{"StatusPartialContent", Const, 0, ""},
		{"StatusPaymentRequired", Const, 0, ""},
		{"StatusPermanentRedirect", Const, 7, ""},
		{"StatusPreconditionFailed", Const, 0, ""},
		{"StatusPreconditionRequired", Const, 6, ""},
		{"StatusProcessing", Const, 7, ""},
		{"StatusProxyAuthRequired", Const, 0, ""},
		{"StatusRequestEntityTooLarge", Const, 0, ""},
		{"StatusRequestHeaderFieldsTooLarge", Const, 6, ""},
		{"StatusRequestTimeout", Const, 0, ""},
		{"StatusRequestURITooLong", Const, 0, ""},
		{"StatusRequestedRangeNotSatisfiable", Const, 0, ""},
		{"StatusResetContent", Const, 0, ""},
		{"StatusSeeOther", Const, 0, ""},
		{"StatusServiceUnavailable", Const, 0, ""},
		{"StatusSwitchingProtocols", Const, 0, ""},
		{"StatusTeapot", Const, 0, ""},
		{"StatusTemporaryRedirect", Const, 0, ""},
		{"StatusText", Func, 0, "func(code int) string"},
		{"StatusTooEarly", Const, 12, ""},
		{"StatusTooManyRequests", Const, 6, ""},
		{"StatusUnauthorized", Const, 0, ""},
		{"StatusUnavailableForLegalReasons", Const, 6, ""},
		{"StatusUnprocessableEntity", Const, 7, ""},
		{"StatusUnsupportedMediaType", Const, 0, ""},
		{"StatusUpgradeRequired", Const, 7, ""},
		{"StatusUseProxy", Const, 0, ""},
		{"StatusVariantAlsoNegotiates", Const, 7, ""},
		{"StripPrefix", Func, 0, "func(prefix string, h Handler) Handler"},
		{"TimeFormat", Const, 0, ""},
		{"TimeoutHandler", Func, 0, "func(h Handler, dt time.Duration, msg string) Handler"},
		{"TrailerPrefix", Const, 8, ""},
		{"Transport", Type, 0, ""},
		{"Transport.Dial", Field, 0, ""},
		{"Transport.DialContext", Field, 7, ""},
		{"Transport.DialTLS", Field, 4, ""},
		{"Transport.DialTLSContext", Field, 14, ""},
		{"Transport.DisableCompression", Field, 0, ""},
		{"Transport.DisableKeepAlives", Field, 0, ""},
		{"Transport.ExpectContinueTimeout", Field, 6, ""},
		{"Transport.ForceAttemptHTTP2", Field, 13, ""},
		{"Transport.GetProxyConnectHeader", Field, 16, ""},
		{"Transport.HTTP2", Field, 24, ""},
		{"Transport.IdleConnTimeout", Field, 7, ""},
		{"Transport.MaxConnsPerHost", Field, 11, ""},
		{"Transport.MaxIdleConns", Field, 7, ""},
		{"Transport.MaxIdleConnsPerHost", Field, 0, ""},
		{"Transport.MaxResponseHeaderBytes", Field, 7, ""},
		{"Transport.OnProxyConnectResponse", Field, 20, ""},
		{"Transport.Protocols", Field, 24, ""},
		{"Transport.Proxy", Field, 0, ""},
		{"Transport.ProxyConnectHeader", Field, 8, ""},
		{"Transport.ReadBufferSize", Field, 13, ""},
		{"Transport.ResponseHeaderTimeout", Field, 1, ""},
		{"Transport.TLSClientConfig", Field, 0, ""},
		{"Transport.TLSHandshakeTimeout", Field, 3, ""},
		{"Transport.TLSNextProto", Field, 6, ""},
		{"Transport.WriteBufferSize", Field, 13, ""},
	},
	"net/http/cgi": {
		{"(*Handler).ServeHTTP", Method, 0, ""},
		{"Handler", Type, 0, ""},
		{"Handler.Args", Field, 0, ""},
		{"Handler.Dir", Field, 0, ""},
		{"Handler.Env", Field, 0, ""},
		{"Handler.InheritEnv", Field, 0, ""},
		{"Handler.Logger", Field, 0, ""},
		{"Handler.Path", Field, 0, ""},
		{"Handler.PathLocationHandler", Field, 0, ""},
		{"Handler.Root", Field, 0, ""},
		{"Handler.Stderr", Field, 7, ""},
		{"Request", Func, 0, "func() (*http.Request, error)"},
		{"RequestFromMap", Func, 0, "func(params map[string]string) (*http.Request, error)"},
		{"Serve", Func, 0, "func(handler http.Handler) error"},
	},
	"net/http/cookiejar": {
		{"(*Jar).Cookies", Method, 1, ""},
		{"(*Jar).SetCookies", Method, 1, ""},
		{"(PublicSuffixList).PublicSuffix", Method, 1, ""},
		{"(PublicSuffixList).String", Method, 1, ""},
		{"Jar", Type, 1, ""},
		{"New", Func, 1, "func(o *Options) (*Jar, error)"},
		{"Options", Type, 1, ""},
		{"Options.PublicSuffixList", Field, 1, ""},
		{"PublicSuffixList", Type, 1, ""},
	},
	"net/http/fcgi": {
		{"ErrConnClosed", Var, 5, ""},
		{"ErrRequestAborted", Var, 5, ""},
		{"ProcessEnv", Func, 9, "func(r *http.Request) map[string]string"},
		{"Serve", Func, 0, "func(l net.Listener, handler http.Handler) error"},
	},
	"net/http/httptest": {
		{"(*ResponseRecorder).Flush", Method, 0, ""},
		{"(*ResponseRecorder).Header", Method, 0, ""},
		{"(*ResponseRecorder).Result", Method, 7, ""},
		{"(*ResponseRecorder).Write", Method, 0, ""},
		{"(*ResponseRecorder).WriteHeader", Method, 0, ""},
		{"(*ResponseRecorder).WriteString", Method, 6, ""},
		{"(*Server).Certificate", Method, 9, ""},
		{"(*Server).Client", Method, 9, ""},
		{"(*Server).Close", Method, 0, ""},
		{"(*Server).CloseClientConnections", Method, 0, ""},
		{"(*Server).Start", Method, 0, ""},
		{"(*Server).StartTLS", Method, 0, ""},
		{"DefaultRemoteAddr", Const, 0, ""},
		{"NewRecorder", Func, 0, "func() *ResponseRecorder"},
		{"NewRequest", Func, 7, "func(method string, target string, body io.Reader) *http.Request"},
		{"NewRequestWithContext", Func, 23, "func(ctx context.Context, method string, target string, body io.Reader) *http.Request"},
		{"NewServer", Func, 0, "func(handler http.Handler) *Server"},
		{"NewTLSServer", Func, 0, "func(handler http.Handler) *Server"},
		{"NewUnstartedServer", Func, 0, "func(handler http.Handler) *Server"},
		{"ResponseRecorder", Type, 0, ""},
		{"ResponseRecorder.Body", Field, 0, ""},
		{"ResponseRecorder.Code", Field, 0, ""},
		{"ResponseRecorder.Flushed", Field, 0, ""},
		{"ResponseRecorder.HeaderMap", Field, 0, ""},
		{"Server", Type, 0, ""},
		{"Server.Config", Field, 0, ""},
		{"Server.EnableHTTP2", Field, 14, ""},
		{"Server.Listener", Field, 0, ""},
		{"Server.TLS", Field, 0, ""},
		{"Server.URL", Field, 0, ""},
	},
	"net/http/httptrace": {
		{"ClientTrace", Type, 7, ""},
		{"ClientTrace.ConnectDone", Field, 7, ""},
		{"ClientTrace.ConnectStart", Field, 7, ""},
		{"ClientTrace.DNSDone", Field, 7, ""},
		{"ClientTrace.DNSStart", Field, 7, ""},
		{"ClientTrace.GetConn", Field, 7, ""},
		{"ClientTrace.Got100Continue", Field, 7, ""},
		{"ClientTrace.Got1xxResponse", Field, 11, ""},
		{"ClientTrace.GotConn", Field, 7, ""},
		{"ClientTrace.GotFirstResponseByte", Field, 7, ""},
		{"ClientTrace.PutIdleConn", Field, 7, ""},
		{"ClientTrace.TLSHandshakeDone", Field, 8, ""},
		{"ClientTrace.TLSHandshakeStart", Field, 8, ""},
		{"ClientTrace.Wait100Continue", Field, 7, ""},
		{"ClientTrace.WroteHeaderField", Field, 11, ""},
		{"ClientTrace.WroteHeaders", Field, 7, ""},
		{"ClientTrace.WroteRequest", Field, 7, ""},
		{"ContextClientTrace", Func, 7, "func(ctx context.Context) *ClientTrace"},
		{"DNSDoneInfo", Type, 7, ""},
		{"DNSDoneInfo.Addrs", Field, 7, ""},
		{"DNSDoneInfo.Coalesced", Field, 7, ""},
		{"DNSDoneInfo.Err", Field, 7, ""},
		{"DNSStartInfo", Type, 7, ""},
		{"DNSStartInfo.Host", Field, 7, ""},
		{"GotConnInfo", Type, 7, ""},
		{"GotConnInfo.Conn", Field, 7, ""},
		{"GotConnInfo.IdleTime", Field, 7, ""},
		{"GotConnInfo.Reused", Field, 7, ""},
		{"GotConnInfo.WasIdle", Field, 7, ""},
		{"WithClientTrace", Func, 7, "func(ctx context.Context, trace *ClientTrace) context.Context"},
		{"WroteRequestInfo", Type, 7, ""},
		{"WroteRequestInfo.Err", Field, 7, ""},
	},
	"net/http/httputil": {
		{"(*ClientConn).Close", Method, 0, ""},
		{"(*ClientConn).Do", Method, 0, ""},
		{"(*ClientConn).Hijack", Method, 0, ""},
		{"(*ClientConn).Pending", Method, 0, ""},
		{"(*ClientConn).Read", Method, 0, ""},
		{"(*ClientConn).Write", Method, 0, ""},
		{"(*ProxyRequest).SetURL", Method, 20, ""},
		{"(*ProxyRequest).SetXForwarded", Method, 20, ""},
		{"(*ReverseProxy).ServeHTTP", Method, 0, ""},
		{"(*ServerConn).Close", Method, 0, ""},
		{"(*ServerConn).Hijack", Method, 0, ""},
		{"(*ServerConn).Pending", Method, 0, ""},
		{"(*ServerConn).Read", Method, 0, ""},
		{"(*ServerConn).Write", Method, 0, ""},
		{"(BufferPool).Get", Method, 6, ""},
		{"(BufferPool).Put", Method, 6, ""},
		{"BufferPool", Type, 6, ""},
		{"ClientConn", Type, 0, ""},
		{"DumpRequest", Func, 0, "func(req *http.Request, body bool) ([]byte, error)"},
		{"DumpRequestOut", Func, 0, "func(req *http.Request, body bool) ([]byte, error)"},
		{"DumpResponse", Func, 0, "func(resp *http.Response, body bool) ([]byte, error)"},
		{"ErrClosed", Var, 0, ""},
		{"ErrLineTooLong", Var, 0, ""},
		{"ErrPersistEOF", Var, 0, ""},
		{"ErrPipeline", Var, 0, ""},
		{"NewChunkedReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"NewChunkedWriter", Func, 0, "func(w io.Writer) io.WriteCloser"},
		{"NewClientConn", Func, 0, "func(c net.Conn, r *bufio.Reader) *ClientConn"},
		{"NewProxyClientConn", Func, 0, "func(c net.Conn, r *bufio.Reader) *ClientConn"},
		{"NewServerConn", Func, 0, "func(c net.Conn, r *bufio.Reader) *ServerConn"},
		{"NewSingleHostReverseProxy", Func, 0, "func(target *url.URL) *ReverseProxy"},
		{"ProxyRequest", Type, 20, ""},
		{"ProxyRequest.In", Field, 20, ""},
		{"ProxyRequest.Out", Field, 20, ""},
		{"ReverseProxy", Type, 0, ""},
		{"ReverseProxy.BufferPool", Field, 6, ""},
		{"ReverseProxy.Director", Field, 0, ""},
		{"ReverseProxy.ErrorHandler", Field, 11, ""},
		{"ReverseProxy.ErrorLog", Field, 4, ""},
		{"ReverseProxy.FlushInterval", Field, 0, ""},
		{"ReverseProxy.ModifyResponse", Field, 8, ""},
		{"ReverseProxy.Rewrite", Field, 20, ""},
		{"ReverseProxy.Transport", Field, 0, ""},
		{"ServerConn", Type, 0, ""},
	},
	"net/http/pprof": {
		{"Cmdline", Func, 0, "func(w http.ResponseWriter, r *http.Request)"},
		{"Handler", Func, 0, "func(name string) http.Handler"},
		{"Index", Func, 0, "func(w http.ResponseWriter, r *http.Request)"},
		{"Profile", Func, 0, "func(w http.ResponseWriter, r *http.Request)"},
		{"Symbol", Func, 0, "func(w http.ResponseWriter, r *http.Request)"},
		{"Trace", Func, 5, "func(w http.ResponseWriter, r *http.Request)"},
	},
	"net/mail": {
		{"(*Address).String", Method, 0, ""},
		{"(*AddressParser).Parse", Method, 5, ""},
		{"(*AddressParser).ParseList", Method, 5, ""},
		{"(Header).AddressList", Method, 0, ""},
		{"(Header).Date", Method, 0, ""},
		{"(Header).Get", Method, 0, ""},
		{"Address", Type, 0, ""},
		{"Address.Address", Field, 0, ""},
		{"Address.Name", Field, 0, ""},
		{"AddressParser", Type, 5, ""},
		{"AddressParser.WordDecoder", Field, 5, ""},
		{"ErrHeaderNotPresent", Var, 0, ""},
		{"Header", Type, 0, ""},
		{"Message", Type, 0, ""},
		{"Message.Body", Field, 0, ""},
		{"Message.Header", Field, 0, ""},
		{"ParseAddress", Func, 1, "func(address string) (*Address, error)"},
		{"ParseAddressList", Func, 1, "func(list string) ([]*Address, error)"},
		{"ParseDate", Func, 8, "func(date string) (time.Time, error)"},
		{"ReadMessage", Func, 0, "func(r io.Reader) (msg *Message, err error)"},
	},
	"net/netip": {
		{"(*Addr).UnmarshalBinary", Method, 18, ""},
		{"(*Addr).UnmarshalText", Method, 18, ""},
		{"(*AddrPort).UnmarshalBinary", Method, 18, ""},
		{"(*AddrPort).UnmarshalText", Method, 18, ""},
		{"(*Prefix).UnmarshalBinary", Method, 18, ""},
		{"(*Prefix).UnmarshalText", Method, 18, ""},
		{"(Addr).AppendBinary", Method, 24, ""},
		{"(Addr).AppendText", Method, 24, ""},
		{"(Addr).AppendTo", Method, 18, ""},
		{"(Addr).As16", Method, 18, ""},
		{"(Addr).As4", Method, 18, ""},
		{"(Addr).AsSlice", Method, 18, ""},
		{"(Addr).BitLen", Method, 18, ""},
		{"(Addr).Compare", Method, 18, ""},
		{"(Addr).Is4", Method, 18, ""},
		{"(Addr).Is4In6", Method, 18, ""},
		{"(Addr).Is6", Method, 18, ""},
		{"(Addr).IsGlobalUnicast", Method, 18, ""},
		{"(Addr).IsInterfaceLocalMulticast", Method, 18, ""},
		{"(Addr).IsLinkLocalMulticast", Method, 18, ""},
		{"(Addr).IsLinkLocalUnicast", Method, 18, ""},
		{"(Addr).IsLoopback", Method, 18, ""},
		{"(Addr).IsMulticast", Method, 18, ""},
		{"(Addr).IsPrivate", Method, 18, ""},
		{"(Addr).IsUnspecified", Method, 18, ""},
		{"(Addr).IsValid", Method, 18, ""},
		{"(Addr).Less", Method, 18, ""},
		{"(Addr).MarshalBinary", Method, 18, ""},
		{"(Addr).MarshalText", Method, 18, ""},
		{"(Addr).Next", Method, 18, ""},
		{"(Addr).Prefix", Method, 18, ""},
		{"(Addr).Prev", Method, 18, ""},
		{"(Addr).String", Method, 18, ""},
		{"(Addr).StringExpanded", Method, 18, ""},
		{"(Addr).Unmap", Method, 18, ""},
		{"(Addr).WithZone", Method, 18, ""},
		{"(Addr).Zone", Method, 18, ""},
		{"(AddrPort).Addr", Method, 18, ""},
		{"(AddrPort).AppendBinary", Method, 24, ""},
		{"(AddrPort).AppendText", Method, 24, ""},
		{"(AddrPort).AppendTo", Method, 18, ""},
		{"(AddrPort).Compare", Method, 22, ""},
		{"(AddrPort).IsValid", Method, 18, ""},
		{"(AddrPort).MarshalBinary", Method, 18, ""},
		{"(AddrPort).MarshalText", Method, 18, ""},
		{"(AddrPort).Port", Method, 18, ""},
		{"(AddrPort).String", Method, 18, ""},
		{"(Prefix).Addr", Method, 18, ""},
		{"(Prefix).AppendBinary", Method, 24, ""},
		{"(Prefix).AppendText", Method, 24, ""},
		{"(Prefix).AppendTo", Method, 18, ""},
		{"(Prefix).Bits", Method, 18, ""},
		{"(Prefix).Compare", Method, 26, ""},
		{"(Prefix).Contains", Method, 18, ""},
		{"(Prefix).IsSingleIP", Method, 18, ""},
		{"(Prefix).IsValid", Method, 18, ""},
		{"(Prefix).MarshalBinary", Method, 18, ""},
		{"(Prefix).MarshalText", Method, 18, ""},
		{"(Prefix).Masked", Method, 18, ""},
		{"(Prefix).Overlaps", Method, 18, ""},
		{"(Prefix).String", Method, 18, ""},
		{"Addr", Type, 18, ""},
		{"AddrFrom16", Func, 18, "func(addr [16]byte) Addr"},
		{"AddrFrom4", Func, 18, "func(addr [4]byte) Addr"},
		{"AddrFromSlice", Func, 18, "func(slice []byte) (ip Addr, ok bool)"},
		{"AddrPort", Type, 18, ""},
		{"AddrPortFrom", Func, 18, "func(ip Addr, port uint16) AddrPort"},
		{"IPv4Unspecified", Func, 18, "func() Addr"},
		{"IPv6LinkLocalAllNodes", Func, 18, "func() Addr"},
		{"IPv6LinkLocalAllRouters", Func, 20, "func() Addr"},
		{"IPv6Loopback", Func, 20, "func() Addr"},
		{"IPv6Unspecified", Func, 18, "func() Addr"},
		{"MustParseAddr", Func, 18, "func(s string) Addr"},
		{"MustParseAddrPort", Func, 18, "func(s string) AddrPort"},
		{"MustParsePrefix", Func, 18, "func(s string) Prefix"},
		{"ParseAddr", Func, 18, "func(s string) (Addr, error)"},
		{"ParseAddrPort", Func, 18, "func(s string) (AddrPort, error)"},
		{"ParsePrefix", Func, 18, "func(s string) (Prefix, error)"},
		{"Prefix", Type, 18, ""},
		{"PrefixFrom", Func, 18, "func(ip Addr, bits int) Prefix"},
	},
	"net/rpc": {
		{"(*Client).Call", Method, 0, ""},
		{"(*Client).Close", Method, 0, ""},
		{"(*Client).Go", Method, 0, ""},
		{"(*Server).Accept", Method, 0, ""},
		{"(*Server).HandleHTTP", Method, 0, ""},
		{"(*Server).Register", Method, 0, ""},
		{"(*Server).RegisterName", Method, 0, ""},
		{"(*Server).ServeCodec", Method, 0, ""},
		{"(*Server).ServeConn", Method, 0, ""},
		{"(*Server).ServeHTTP", Method, 0, ""},
		{"(*Server).ServeRequest", Method, 0, ""},
		{"(ClientCodec).Close", Method, 0, ""},
		{"(ClientCodec).ReadResponseBody", Method, 0, ""},
		{"(ClientCodec).ReadResponseHeader", Method, 0, ""},
		{"(ClientCodec).WriteRequest", Method, 0, ""},
		{"(ServerCodec).Close", Method, 0, ""},
		{"(ServerCodec).ReadRequestBody", Method, 0, ""},
		{"(ServerCodec).ReadRequestHeader", Method, 0, ""},
		{"(ServerCodec).WriteResponse", Method, 0, ""},
		{"(ServerError).Error", Method, 0, ""},
		{"Accept", Func, 0, "func(lis net.Listener)"},
		{"Call", Type, 0, ""},
		{"Call.Args", Field, 0, ""},
		{"Call.Done", Field, 0, ""},
		{"Call.Error", Field, 0, ""},
		{"Call.Reply", Field, 0, ""},
		{"Call.ServiceMethod", Field, 0, ""},
		{"Client", Type, 0, ""},
		{"ClientCodec", Type, 0, ""},
		{"DefaultDebugPath", Const, 0, ""},
		{"DefaultRPCPath", Const, 0, ""},
		{"DefaultServer", Var, 0, ""},
		{"Dial", Func, 0, "func(network string, address string) (*Client, error)"},
		{"DialHTTP", Func, 0, "func(network string, address string) (*Client, error)"},
		{"DialHTTPPath", Func, 0, "func(network string, address string, path string) (*Client, error)"},
		{"ErrShutdown", Var, 0, ""},
		{"HandleHTTP", Func, 0, "func()"},
		{"NewClient", Func, 0, "func(conn io.ReadWriteCloser) *Client"},
		{"NewClientWithCodec", Func, 0, "func(codec ClientCodec) *Client"},
		{"NewServer", Func, 0, "func() *Server"},
		{"Register", Func, 0, "func(rcvr any) error"},
		{"RegisterName", Func, 0, "func(name string, rcvr any) error"},
		{"Request", Type, 0, ""},
		{"Request.Seq", Field, 0, ""},
		{"Request.ServiceMethod", Field, 0, ""},
		{"Response", Type, 0, ""},
		{"Response.Error", Field, 0, ""},
		{"Response.Seq", Field, 0, ""},
		{"Response.ServiceMethod", Field, 0, ""},
		{"ServeCodec", Func, 0, "func(codec ServerCodec)"},
		{"ServeConn", Func, 0, "func(conn io.ReadWriteCloser)"},
		{"ServeRequest", Func, 0, "func(codec ServerCodec) error"},
		{"Server", Type, 0, ""},
		{"ServerCodec", Type, 0, ""},
		{"ServerError", Type, 0, ""},
	},
	"net/rpc/jsonrpc": {
		{"Dial", Func, 0, "func(network string, address string) (*rpc.Client, error)"},
		{"NewClient", Func, 0, "func(conn io.ReadWriteCloser) *rpc.Client"},
		{"NewClientCodec", Func, 0, "func(conn io.ReadWriteCloser) rpc.ClientCodec"},
		{"NewServerCodec", Func, 0, "func(conn io.ReadWriteCloser) rpc.ServerCodec"},
		{"ServeConn", Func, 0, "func(conn io.ReadWriteCloser)"},
	},
	"net/smtp": {
		{"(*Client).Auth", Method, 0, ""},
		{"(*Client).Close", Method, 2, ""},
		{"(*Client).Data", Method, 0, ""},
		{"(*Client).Extension", Method, 0, ""},
		{"(*Client).Hello", Method, 1, ""},
		{"(*Client).Mail", Method, 0, ""},
		{"(*Client).Noop", Method, 10, ""},
		{"(*Client).Quit", Method, 0, ""},
		{"(*Client).Rcpt", Method, 0, ""},
		{"(*Client).Reset", Method, 0, ""},
		{"(*Client).StartTLS", Method, 0, ""},
		{"(*Client).TLSConnectionState", Method, 5, ""},
		{"(*Client).Verify", Method, 0, ""},
		{"(Auth).Next", Method, 0, ""},
		{"(Auth).Start", Method, 0, ""},
		{"Auth", Type, 0, ""},
		{"CRAMMD5Auth", Func, 0, "func(username string, secret string) Auth"},
		{"Client", Type, 0, ""},
		{"Client.Text", Field, 0, ""},
		{"Dial", Func, 0, "func(addr string) (*Client, error)"},
		{"NewClient", Func, 0, "func(conn net.Conn, host string) (*Client, error)"},
		{"PlainAuth", Func, 0, "func(identity string, username string, password string, host string) Auth"},
		{"SendMail", Func, 0, "func(addr string, a Auth, from string, to []string, msg []byte) error"},
		{"ServerInfo", Type, 0, ""},
		{"ServerInfo.Auth", Field, 0, ""},
		{"ServerInfo.Name", Field, 0, ""},
		{"ServerInfo.TLS", Field, 0, ""},
	},
	"net/textproto": {
		{"(*Conn).Close", Method, 0, ""},
		{"(*Conn).Cmd", Method, 0, ""},
		{"(*Conn).DotReader", Method, 0, ""},
		{"(*Conn).DotWriter", Method, 0, ""},
		{"(*Conn).EndRequest", Method, 0, ""},
		{"(*Conn).EndResponse", Method, 0, ""},
		{"(*Conn).Next", Method, 0, ""},
		{"(*Conn).PrintfLine", Method, 0, ""},
		{"(*Conn).ReadCodeLine", Method, 0, ""},
		{"(*Conn).ReadContinuedLine", Method, 0, ""},
		{"(*Conn).ReadContinuedLineBytes", Method, 0, ""},
		{"(*Conn).ReadDotBytes", Method, 0, ""},
		{"(*Conn).ReadDotLines", Method, 0, ""},
		{"(*Conn).ReadLine", Method, 0, ""},
		{"(*Conn).ReadLineBytes", Method, 0, ""},
		{"(*Conn).ReadMIMEHeader", Method, 0, ""},
		{"(*Conn).ReadResponse", Method, 0, ""},
		{"(*Conn).StartRequest", Method, 0, ""},
		{"(*Conn).StartResponse", Method, 0, ""},
		{"(*Error).Error", Method, 0, ""},
		{"(*Pipeline).EndRequest", Method, 0, ""},
		{"(*Pipeline).EndResponse", Method, 0, ""},
		{"(*Pipeline).Next", Method, 0, ""},
		{"(*Pipeline).StartRequest", Method, 0, ""},
		{"(*Pipeline).StartResponse", Method, 0, ""},
		{"(*Reader).DotReader", Method, 0, ""},
		{"(*Reader).ReadCodeLine", Method, 0, ""},
		{"(*Reader).ReadContinuedLine", Method, 0, ""},
		{"(*Reader).ReadContinuedLineBytes", Method, 0, ""},
		{"(*Reader).ReadDotBytes", Method, 0, ""},
		{"(*Reader).ReadDotLines", Method, 0, ""},
		{"(*Reader).ReadLine", Method, 0, ""},
		{"(*Reader).ReadLineBytes", Method, 0, ""},
		{"(*Reader).ReadMIMEHeader", Method, 0, ""},
		{"(*Reader).ReadResponse", Method, 0, ""},
		{"(*Writer).DotWriter", Method, 0, ""},
		{"(*Writer).PrintfLine", Method, 0, ""},
		{"(MIMEHeader).Add", Method, 0, ""},
		{"(MIMEHeader).Del", Method, 0, ""},
		{"(MIMEHeader).Get", Method, 0, ""},
		{"(MIMEHeader).Set", Method, 0, ""},
		{"(MIMEHeader).Values", Method, 14, ""},
		{"(ProtocolError).Error", Method, 0, ""},
		{"CanonicalMIMEHeaderKey", Func, 0, "func(s string) string"},
		{"Conn", Type, 0, ""},
		{"Conn.Pipeline", Field, 0, ""},
		{"Conn.Reader", Field, 0, ""},
		{"Conn.Writer", Field, 0, ""},
		{"Dial", Func, 0, "func(network string, addr string) (*Conn, error)"},
		{"Error", Type, 0, ""},
		{"Error.Code", Field, 0, ""},
		{"Error.Msg", Field, 0, ""},
		{"MIMEHeader", Type, 0, ""},
		{"NewConn", Func, 0, "func(conn io.ReadWriteCloser) *Conn"},
		{"NewReader", Func, 0, "func(r *bufio.Reader) *Reader"},
		{"NewWriter", Func, 0, "func(w *bufio.Writer) *Writer"},
		{"Pipeline", Type, 0, ""},
		{"ProtocolError", Type, 0, ""},
		{"Reader", Type, 0, ""},
		{"Reader.R", Field, 0, ""},
		{"TrimBytes", Func, 1, "func(b []byte) []byte"},
		{"TrimString", Func, 1, "func(s string) string"},
		{"Writer", Type, 0, ""},
		{"Writer.W", Field, 0, ""},
	},
	"net/url": {
		{"(*Error).Error", Method, 0, ""},
		{"(*Error).Temporary", Method, 6, ""},
		{"(*Error).Timeout", Method, 6, ""},
		{"(*Error).Unwrap", Method, 13, ""},
		{"(*URL).AppendBinary", Method, 24, ""},
		{"(*URL).EscapedFragment", Method, 15, ""},
		{"(*URL).EscapedPath", Method, 5, ""},
		{"(*URL).Hostname", Method, 8, ""},
		{"(*URL).IsAbs", Method, 0, ""},
		{"(*URL).JoinPath", Method, 19, ""},
		{"(*URL).MarshalBinary", Method, 8, ""},
		{"(*URL).Parse", Method, 0, ""},
		{"(*URL).Port", Method, 8, ""},
		{"(*URL).Query", Method, 0, ""},
		{"(*URL).Redacted", Method, 15, ""},
		{"(*URL).RequestURI", Method, 0, ""},
		{"(*URL).ResolveReference", Method, 0, ""},
		{"(*URL).String", Method, 0, ""},
		{"(*URL).UnmarshalBinary", Method, 8, ""},
		{"(*Userinfo).Password", Method, 0, ""},
		{"(*Userinfo).String", Method, 0, ""},
		{"(*Userinfo).Username", Method, 0, ""},
		{"(EscapeError).Error", Method, 0, ""},
		{"(InvalidHostError).Error", Method, 6, ""},
		{"(Values).Add", Method, 0, ""},
		{"(Values).Del", Method, 0, ""},
		{"(Values).Encode", Method, 0, ""},
		{"(Values).Get", Method, 0, ""},
		{"(Values).Has", Method, 17, ""},
		{"(Values).Set", Method, 0, ""},
		{"Error", Type, 0, ""},
		{"Error.Err", Field, 0, ""},
		{"Error.Op", Field, 0, ""},
		{"Error.URL", Field, 0, ""},
		{"EscapeError", Type, 0, ""},
		{"InvalidHostError", Type, 6, ""},
		{"JoinPath", Func, 19, "func(base string, elem ...string) (result string, err error)"},
		{"Parse", Func, 0, "func(rawURL string) (*URL, error)"},
		{"ParseQuery", Func, 0, "func(query string) (Values, error)"},
		{"ParseRequestURI", Func, 0, "func(rawURL string) (*URL, error)"},
		{"PathEscape", Func, 8, "func(s string) string"},
		{"PathUnescape", Func, 8, "func(s string) (string, error)"},
		{"QueryEscape", Func, 0, "func(s string) string"},
		{"QueryUnescape", Func, 0, "func(s string) (string, error)"},
		{"URL", Type, 0, ""},
		{"URL.ForceQuery", Field, 7, ""},
		{"URL.Fragment", Field, 0, ""},
		{"URL.Host", Field, 0, ""},
		{"URL.OmitHost", Field, 19, ""},
		{"URL.Opaque", Field, 0, ""},
		{"URL.Path", Field, 0, ""},
		{"URL.RawFragment", Field, 15, ""},
		{"URL.RawPath", Field, 5, ""},
		{"URL.RawQuery", Field, 0, ""},
		{"URL.Scheme", Field, 0, ""},
		{"URL.User", Field, 0, ""},
		{"User", Func, 0, "func(username string) *Userinfo"},
		{"UserPassword", Func, 0, "func(username string, password string) *Userinfo"},
		{"Userinfo", Type, 0, ""},
		{"Values", Type, 0, ""},
	},
	"os": {
		{"(*File).Chdir", Method, 0, ""},
		{"(*File).Chmod", Method, 0, ""},
		{"(*File).Chown", Method, 0, ""},
		{"(*File).Close", Method, 0, ""},
		{"(*File).Fd", Method, 0, ""},
		{"(*File).Name", Method, 0, ""},
		{"(*File).Read", Method, 0, ""},
		{"(*File).ReadAt", Method, 0, ""},
		{"(*File).ReadDir", Method, 16, ""},
		{"(*File).ReadFrom", Method, 15, ""},
		{"(*File).Readdir", Method, 0, ""},
		{"(*File).Readdirnames", Method, 0, ""},
		{"(*File).Seek", Method, 0, ""},
		{"(*File).SetDeadline", Method, 10, ""},
		{"(*File).SetReadDeadline", Method, 10, ""},
		{"(*File).SetWriteDeadline", Method, 10, ""},
		{"(*File).Stat", Method, 0, ""},
		{"(*File).Sync", Method, 0, ""},
		{"(*File).SyscallConn", Method, 12, ""},
		{"(*File).Truncate", Method, 0, ""},
		{"(*File).Write", Method, 0, ""},
		{"(*File).WriteAt", Method, 0, ""},
		{"(*File).WriteString", Method, 0, ""},
		{"(*File).WriteTo", Method, 22, ""},
		{"(*LinkError).Error", Method, 0, ""},
		{"(*LinkError).Unwrap", Method, 13, ""},
		{"(*PathError).Error", Method, 0, ""},
		{"(*PathError).Timeout", Method, 10, ""},
		{"(*PathError).Unwrap", Method, 13, ""},
		{"(*Process).Kill", Method, 0, ""},
		{"(*Process).Release", Method, 0, ""},
		{"(*Process).Signal", Method, 0, ""},
		{"(*Process).Wait", Method, 0, ""},
		{"(*Process).WithHandle", Method, 26, ""},
		{"(*ProcessState).ExitCode", Method, 12, ""},
		{"(*ProcessState).Exited", Method, 0, ""},
		{"(*ProcessState).Pid", Method, 0, ""},
		{"(*ProcessState).String", Method, 0, ""},
		{"(*ProcessState).Success", Method, 0, ""},
		{"(*ProcessState).Sys", Method, 0, ""},
		{"(*ProcessState).SysUsage", Method, 0, ""},
		{"(*ProcessState).SystemTime", Method, 0, ""},
		{"(*ProcessState).UserTime", Method, 0, ""},
		{"(*Root).Chmod", Method, 25, ""},
		{"(*Root).Chown", Method, 25, ""},
		{"(*Root).Chtimes", Method, 25, ""},
		{"(*Root).Close", Method, 24, ""},
		{"(*Root).Create", Method, 24, ""},
		{"(*Root).FS", Method, 24, ""},
		{"(*Root).Lchown", Method, 25, ""},
		{"(*Root).Link", Method, 25, ""},
		{"(*Root).Lstat", Method, 24, ""},
		{"(*Root).Mkdir", Method, 24, ""},
		{"(*Root).MkdirAll", Method, 25, ""},
		{"(*Root).Name", Method, 24, ""},
		{"(*Root).Open", Method, 24, ""},
		{"(*Root).OpenFile", Method, 24, ""},
		{"(*Root).OpenRoot", Method, 24, ""},
		{"(*Root).ReadFile", Method, 25, ""},
		{"(*Root).Readlink", Method, 25, ""},
		{"(*Root).Remove", Method, 24, ""},
		{"(*Root).RemoveAll", Method, 25, ""},
		{"(*Root).Rename", Method, 25, ""},
		{"(*Root).Stat", Method, 24, ""},
		{"(*Root).Symlink", Method, 25, ""},
		{"(*Root).WriteFile", Method, 25, ""},
		{"(*SyscallError).Error", Method, 0, ""},
		{"(*SyscallError).Timeout", Method, 10, ""},
		{"(*SyscallError).Unwrap", Method, 13, ""},
		{"(FileInfo).IsDir", Method, 0, ""},
		{"(FileInfo).ModTime", Method, 0, ""},
		{"(FileInfo).Mode", Method, 0, ""},
		{"(FileInfo).Name", Method, 0, ""},
		{"(FileInfo).Size", Method, 0, ""},
		{"(FileInfo).Sys", Method, 0, ""},
		{"(FileMode).IsDir", Method, 0, ""},
		{"(FileMode).IsRegular", Method, 1, ""},
		{"(FileMode).Perm", Method, 0, ""},
		{"(FileMode).String", Method, 0, ""},
		{"(Signal).Signal", Method, 0, ""},
		{"(Signal).String", Method, 0, ""},
		{"Args", Var, 0, ""},
		{"Chdir", Func, 0, "func(dir string) error"},
		{"Chmod", Func, 0, "func(name string, mode FileMode) error"},
		{"Chown", Func, 0, "func(name string, uid int, gid int) error"},
		{"Chtimes", Func, 0, "func(name string, atime time.Time, mtime time.Time) error"},
		{"Clearenv", Func, 0, "func()"},
		{"CopyFS", Func, 23, "func(dir string, fsys fs.FS) error"},
		{"Create", Func, 0, "func(name string) (*File, error)"},
		{"CreateTemp", Func, 16, "func(dir string, pattern string) (*File, error)"},
		{"DevNull", Const, 0, ""},
		{"DirEntry", Type, 16, ""},
		{"DirFS", Func, 16, "func(dir string) fs.FS"},
		{"Environ", Func, 0, "func() []string"},
		{"ErrClosed", Var, 8, ""},
		{"ErrDeadlineExceeded", Var, 15, ""},
		{"ErrExist", Var, 0, ""},
		{"ErrInvalid", Var, 0, ""},
		{"ErrNoDeadline", Var, 10, ""},
		{"ErrNoHandle", Var, 26, ""},
		{"ErrNotExist", Var, 0, ""},
		{"ErrPermission", Var, 0, ""},
		{"ErrProcessDone", Var, 16, ""},
		{"Executable", Func, 8, "func() (string, error)"},
		{"Exit", Func, 0, "func(code int)"},
		{"Expand", Func, 0, "func(s string, mapping func(string) string) string"},
		{"ExpandEnv", Func, 0, "func(s string) string"},
		{"File", Type, 0, ""},
		{"FileInfo", Type, 0, ""},
		{"FileMode", Type, 0, ""},
		{"FindProcess", Func, 0, "func(pid int) (*Process, error)"},
		{"Getegid", Func, 0, "func() int"},
		{"Getenv", Func, 0, "func(key string) string"},
		{"Geteuid", Func, 0, "func() int"},
		{"Getgid", Func, 0, "func() int"},
		{"Getgroups", Func, 0, "func() ([]int, error)"},
		{"Getpagesize", Func, 0, "func() int"},
		{"Getpid", Func, 0, "func() int"},
		{"Getppid", Func, 0, "func() int"},
		{"Getuid", Func, 0, "func() int"},
		{"Getwd", Func, 0, "func() (dir string, err error)"},
		{"Hostname", Func, 0, "func() (name string, err error)"},
		{"Interrupt", Var, 0, ""},
		{"IsExist", Func, 0, "func(err error) bool"},
		{"IsNotExist", Func, 0, "func(err error) bool"},
		{"IsPathSeparator", Func, 0, "func(c uint8) bool"},
		{"IsPermission", Func, 0, "func(err error) bool"},
		{"IsTimeout", Func, 10, "func(err error) bool"},
		{"Kill", Var, 0, ""},
		{"Lchown", Func, 0, "func(name string, uid int, gid int) error"},
		{"Link", Func, 0, "func(oldname string, newname string) error"},
		{"LinkError", Type, 0, ""},
		{"LinkError.Err", Field, 0, ""},
		{"LinkError.New", Field, 0, ""},
		{"LinkError.Old", Field, 0, ""},
		{"LinkError.Op", Field, 0, ""},
		{"LookupEnv", Func, 5, "func(key string) (string, bool)"},
		{"Lstat", Func, 0, "func(name string) (FileInfo, error)"},
		{"Mkdir", Func, 0, "func(name string, perm FileMode) error"},
		{"MkdirAll", Func, 0, "func(path string, perm FileMode) error"},
		{"MkdirTemp", Func, 16, "func(dir string, pattern string) (string, error)"},
		{"ModeAppend", Const, 0, ""},
		{"ModeCharDevice", Const, 0, ""},
		{"ModeDevice", Const, 0, ""},
		{"ModeDir", Const, 0, ""},
		{"ModeExclusive", Const, 0, ""},
		{"ModeIrregular", Const, 11, ""},
		{"ModeNamedPipe", Const, 0, ""},
		{"ModePerm", Const, 0, ""},
		{"ModeSetgid", Const, 0, ""},
		{"ModeSetuid", Const, 0, ""},
		{"ModeSocket", Const, 0, ""},
		{"ModeSticky", Const, 0, ""},
		{"ModeSymlink", Const, 0, ""},
		{"ModeTemporary", Const, 0, ""},
		{"ModeType", Const, 0, ""},
		{"NewFile", Func, 0, "func(fd uintptr, name string) *File"},
		{"NewSyscallError", Func, 0, "func(syscall string, err error) error"},
		{"O_APPEND", Const, 0, ""},
		{"O_CREATE", Const, 0, ""},
		{"O_EXCL", Const, 0, ""},
		{"O_RDONLY", Const, 0, ""},
		{"O_RDWR", Const, 0, ""},
		{"O_SYNC", Const, 0, ""},
		{"O_TRUNC", Const, 0, ""},
		{"O_WRONLY", Const, 0, ""},
		{"Open", Func, 0, "func(name string) (*File, error)"},
		{"OpenFile", Func, 0, "func(name string, flag int, perm FileMode) (*File, error)"},
		{"OpenInRoot", Func, 24, "func(dir string, name string) (*File, error)"},
		{"OpenRoot", Func, 24, "func(name string) (*Root, error)"},
		{"PathError", Type, 0, ""},
		{"PathError.Err", Field, 0, ""},
		{"PathError.Op", Field, 0, ""},
		{"PathError.Path", Field, 0, ""},
		{"PathListSeparator", Const, 0, ""},
		{"PathSeparator", Const, 0, ""},
		{"Pipe", Func, 0, "func() (r *File, w *File, err error)"},
		{"ProcAttr", Type, 0, ""},
		{"ProcAttr.Dir", Field, 0, ""},
		{"ProcAttr.Env", Field, 0, ""},
		{"ProcAttr.Files", Field, 0, ""},
		{"ProcAttr.Sys", Field, 0, ""},
		{"Process", Type, 0, ""},
		{"Process.Pid", Field, 0, ""},
		{"ProcessState", Type, 0, ""},
		{"ReadDir", Func, 16, "func(name string) ([]DirEntry, error)"},
		{"ReadFile", Func, 16, "func(name string) ([]byte, error)"},
		{"Readlink", Func, 0, "func(name string) (string, error)"},
		{"Remove", Func, 0, "func(name string) error"},
		{"RemoveAll", Func, 0, "func(path string) error"},
		{"Rename", Func, 0, "func(oldpath string, newpath string) error"},
		{"Root", Type, 24, ""},
		{"SEEK_CUR", Const, 0, ""},
		{"SEEK_END", Const, 0, ""},
		{"SEEK_SET", Const, 0, ""},
		{"SameFile", Func, 0, "func(fi1 FileInfo, fi2 FileInfo) bool"},
		{"Setenv", Func, 0, "func(key string, value string) error"},
		{"Signal", Type, 0, ""},
		{"StartProcess", Func, 0, "func(name string, argv []string, attr *ProcAttr) (*Process, error)"},
		{"Stat", Func, 0, "func(name string) (FileInfo, error)"},
		{"Stderr", Var, 0, ""},
		{"Stdin", Var, 0, ""},
		{"Stdout", Var, 0, ""},
		{"Symlink", Func, 0, "func(oldname string, newname string) error"},
		{"SyscallError", Type, 0, ""},
		{"SyscallError.Err", Field, 0, ""},
		{"SyscallError.Syscall", Field, 0, ""},
		{"TempDir", Func, 0, "func() string"},
		{"Truncate", Func, 0, "func(name string, size int64) error"},
		{"Unsetenv", Func, 4, "func(key string) error"},
		{"UserCacheDir", Func, 11, "func() (string, error)"},
		{"UserConfigDir", Func, 13, "func() (string, error)"},
		{"UserHomeDir", Func, 12, "func() (string, error)"},
		{"WriteFile", Func, 16, "func(name string, data []byte, perm FileMode) error"},
	},
	"os/exec": {
		{"(*Cmd).CombinedOutput", Method, 0, ""},
		{"(*Cmd).Environ", Method, 19, ""},
		{"(*Cmd).Output", Method, 0, ""},
		{"(*Cmd).Run", Method, 0, ""},
		{"(*Cmd).Start", Method, 0, ""},
		{"(*Cmd).StderrPipe", Method, 0, ""},
		{"(*Cmd).StdinPipe", Method, 0, ""},
		{"(*Cmd).StdoutPipe", Method, 0, ""},
		{"(*Cmd).String", Method, 13, ""},
		{"(*Cmd).Wait", Method, 0, ""},
		{"(*Error).Error", Method, 0, ""},
		{"(*Error).Unwrap", Method, 13, ""},
		{"(*ExitError).Error", Method, 0, ""},
		{"(ExitError).ExitCode", Method, 12, ""},
		{"(ExitError).Exited", Method, 0, ""},
		{"(ExitError).Pid", Method, 0, ""},
		{"(ExitError).String", Method, 0, ""},
		{"(ExitError).Success", Method, 0, ""},
		{"(ExitError).Sys", Method, 0, ""},
		{"(ExitError).SysUsage", Method, 0, ""},
		{"(ExitError).SystemTime", Method, 0, ""},
		{"(ExitError).UserTime", Method, 0, ""},
		{"Cmd", Type, 0, ""},
		{"Cmd.Args", Field, 0, ""},
		{"Cmd.Cancel", Field, 20, ""},
		{"Cmd.Dir", Field, 0, ""},
		{"Cmd.Env", Field, 0, ""},
		{"Cmd.Err", Field, 19, ""},
		{"Cmd.ExtraFiles", Field, 0, ""},
		{"Cmd.Path", Field, 0, ""},
		{"Cmd.Process", Field, 0, ""},
		{"Cmd.ProcessState", Field, 0, ""},
		{"Cmd.Stderr", Field, 0, ""},
		{"Cmd.Stdin", Field, 0, ""},
		{"Cmd.Stdout", Field, 0, ""},
		{"Cmd.SysProcAttr", Field, 0, ""},
		{"Cmd.WaitDelay", Field, 20, ""},
		{"Command", Func, 0, "func(name string, arg ...string) *Cmd"},
		{"CommandContext", Func, 7, "func(ctx context.Context, name string, arg ...string) *Cmd"},
		{"ErrDot", Var, 19, ""},
		{"ErrNotFound", Var, 0, ""},
		{"ErrWaitDelay", Var, 20, ""},
		{"Error", Type, 0, ""},
		{"Error.Err", Field, 0, ""},
		{"Error.Name", Field, 0, ""},
		{"ExitError", Type, 0, ""},
		{"ExitError.ProcessState", Field, 0, ""},
		{"ExitError.Stderr", Field, 6, ""},
		{"LookPath", Func, 0, "func(file string) (string, error)"},
	},
	"os/signal": {
		{"Ignore", Func, 5, "func(sig ...os.Signal)"},
		{"Ignored", Func, 11, "func(sig os.Signal) bool"},
		{"Notify", Func, 0, "func(c chan<- os.Signal, sig ...os.Signal)"},
		{"NotifyContext", Func, 16, "func(parent context.Context, signals ...os.Signal) (ctx context.Context, stop context.CancelFunc)"},
		{"Reset", Func, 5, "func(sig ...os.Signal)"},
		{"Stop", Func, 1, "func(c chan<- os.Signal)"},
	},
	"os/user": {
		{"(*User).GroupIds", Method, 7, ""},
		{"(UnknownGroupError).Error", Method, 7, ""},
		{"(UnknownGroupIdError).Error", Method, 7, ""},
		{"(UnknownUserError).Error", Method, 0, ""},
		{"(UnknownUserIdError).Error", Method, 0, ""},
		{"Current", Func, 0, "func() (*User, error)"},
		{"Group", Type, 7, ""},
		{"Group.Gid", Field, 7, ""},
		{"Group.Name", Field, 7, ""},
		{"Lookup", Func, 0, "func(username string) (*User, error)"},
		{"LookupGroup", Func, 7, "func(name string) (*Group, error)"},
		{"LookupGroupId", Func, 7, "func(gid string) (*Group, error)"},
		{"LookupId", Func, 0, "func(uid string) (*User, error)"},
		{"UnknownGroupError", Type, 7, ""},
		{"UnknownGroupIdError", Type, 7, ""},
		{"UnknownUserError", Type, 0, ""},
		{"UnknownUserIdError", Type, 0, ""},
		{"User", Type, 0, ""},
		{"User.Gid", Field, 0, ""},
		{"User.HomeDir", Field, 0, ""},
		{"User.Name", Field, 0, ""},
		{"User.Uid", Field, 0, ""},
		{"User.Username", Field, 0, ""},
	},
	"path": {
		{"Base", Func, 0, "func(path string) string"},
		{"Clean", Func, 0, "func(path string) string"},
		{"Dir", Func, 0, "func(path string) string"},
		{"ErrBadPattern", Var, 0, ""},
		{"Ext", Func, 0, "func(path string) string"},
		{"IsAbs", Func, 0, "func(path string) bool"},
		{"Join", Func, 0, "func(elem ...string) string"},
		{"Match", Func, 0, "func(pattern string, name string) (matched bool, err error)"},
		{"Split", Func, 0, "func(path string) (dir string, file string)"},
	},
	"path/filepath": {
		{"Abs", Func, 0, "func(path string) (string, error)"},
		{"Base", Func, 0, "func(path string) string"},
		{"Clean", Func, 0, "func(path string) string"},
		{"Dir", Func, 0, "func(path string) string"},
		{"ErrBadPattern", Var, 0, ""},
		{"EvalSymlinks", Func, 0, "func(path string) (string, error)"},
		{"Ext", Func, 0, "func(path string) string"},
		{"FromSlash", Func, 0, "func(path string) string"},
		{"Glob", Func, 0, "func(pattern string) (matches []string, err error)"},
		{"HasPrefix", Func, 0, "func(p string, prefix string) bool"},
		{"IsAbs", Func, 0, "func(path string) bool"},
		{"IsLocal", Func, 20, "func(path string) bool"},
		{"Join", Func, 0, "func(elem ...string) string"},
		{"ListSeparator", Const, 0, ""},
		{"Localize", Func, 23, "func(path string) (string, error)"},
		{"Match", Func, 0, "func(pattern string, name string) (matched bool, err error)"},
		{"Rel", Func, 0, "func(basePath string, targPath string) (string, error)"},
		{"Separator", Const, 0, ""},
		{"SkipAll", Var, 20, ""},
		{"SkipDir", Var, 0, ""},
		{"Split", Func, 0, "func(path string) (dir string, file string)"},
		{"SplitList", Func, 0, "func(path string) []string"},
		{"ToSlash", Func, 0, "func(path string) string"},
		{"VolumeName", Func, 0, "func(path string) string"},
		{"Walk", Func, 0, "func(root string, fn WalkFunc) error"},
		{"WalkDir", Func, 16, "func(root string, fn fs.WalkDirFunc) error"},
		{"WalkFunc", Type, 0, ""},
	},
	"plugin": {
		{"(*Plugin).Lookup", Method, 8, ""},
		{"Open", Func, 8, "func(path string) (*Plugin, error)"},
		{"Plugin", Type, 8, ""},
		{"Symbol", Type, 8, ""},
	},
	"reflect": {
		{"(*MapIter).Key", Method, 12, ""},
		{"(*MapIter).Next", Method, 12, ""},
		{"(*MapIter).Reset", Method, 18, ""},
		{"(*MapIter).Value", Method, 12, ""},
		{"(*ValueError).Error", Method, 0, ""},
		{"(ChanDir).String", Method, 0, ""},
		{"(Kind).String", Method, 0, ""},
		{"(Method).IsExported", Method, 17, ""},
		{"(StructField).IsExported", Method, 17, ""},
		{"(StructTag).Get", Method, 0, ""},
		{"(StructTag).Lookup", Method, 7, ""},
		{"(Type).Align", Method, 0, ""},
		{"(Type).AssignableTo", Method, 0, ""},
		{"(Type).Bits", Method, 0, ""},
		{"(Type).CanSeq", Method, 23, ""},
		{"(Type).CanSeq2", Method, 23, ""},
		{"(Type).ChanDir", Method, 0, ""},
		{"(Type).Comparable", Method, 4, ""},
		{"(Type).ConvertibleTo", Method, 1, ""},
		{"(Type).Elem", Method, 0, ""},
		{"(Type).Field", Method, 0, ""},
		{"(Type).FieldAlign", Method, 0, ""},
		{"(Type).FieldByIndex", Method, 0, ""},
		{"(Type).FieldByName", Method, 0, ""},
		{"(Type).FieldByNameFunc", Method, 0, ""},
		{"(Type).Fields", Method, 26, ""},
		{"(Type).Implements", Method, 0, ""},
		{"(Type).In", Method, 0, ""},
		{"(Type).Ins", Method, 26, ""},
		{"(Type).IsVariadic", Method, 0, ""},
		{"(Type).Key", Method, 0, ""},
		{"(Type).Kind", Method, 0, ""},
		{"(Type).Len", Method, 0, ""},
		{"(Type).Method", Method, 0, ""},
		{"(Type).MethodByName", Method, 0, ""},
		{"(Type).Methods", Method, 26, ""},
		{"(Type).Name", Method, 0, ""},
		{"(Type).NumField", Method, 0, ""},
		{"(Type).NumIn", Method, 0, ""},
		{"(Type).NumMethod", Method, 0, ""},
		{"(Type).NumOut", Method, 0, ""},
		{"(Type).Out", Method, 0, ""},
		{"(Type).Outs", Method, 26, ""},
		{"(Type).OverflowComplex", Method, 23, ""},
		{"(Type).OverflowFloat", Method, 23, ""},
		{"(Type).OverflowInt", Method, 23, ""},
		{"(Type).OverflowUint", Method, 23, ""},
		{"(Type).PkgPath", Method, 0, ""},
		{"(Type).Size", Method, 0, ""},
		{"(Type).String", Method, 0, ""},
		{"(Value).Addr", Method, 0, ""},
		{"(Value).Bool", Method, 0, ""},
		{"(Value).Bytes", Method, 0, ""},
		{"(Value).Call", Method, 0, ""},
		{"(Value).CallSlice", Method, 0, ""},
		{"(Value).CanAddr", Method, 0, ""},
		{"(Value).CanComplex", Method, 18, ""},
		{"(Value).CanConvert", Method, 17, ""},
		{"(Value).CanFloat", Method, 18, ""},
		{"(Value).CanInt", Method, 18, ""},
		{"(Value).CanInterface", Method, 0, ""},
		{"(Value).CanSet", Method, 0, ""},
		{"(Value).CanUint", Method, 18, ""},
		{"(Value).Cap", Method, 0, ""},
		{"(Value).Clear", Method, 21, ""},
		{"(Value).Close", Method, 0, ""},
		{"(Value).Comparable", Method, 20, ""},
		{"(Value).Complex", Method, 0, ""},
		{"(Value).Convert", Method, 1, ""},
		{"(Value).Elem", Method, 0, ""},
		{"(Value).Equal", Method, 20, ""},
		{"(Value).Field", Method, 0, ""},
		{"(Value).FieldByIndex", Method, 0, ""},
		{"(Value).FieldByIndexErr", Method, 18, ""},
		{"(Value).FieldByName", Method, 0, ""},
		{"(Value).FieldByNameFunc", Method, 0, ""},
		{"(Value).Fields", Method, 26, ""},
		{"(Value).Float", Method, 0, ""},
		{"(Value).Grow", Method, 20, ""},
		{"(Value).Index", Method, 0, ""},
		{"(Value).Int", Method, 0, ""},
		{"(Value).Interface", Method, 0, ""},
		{"(Value).InterfaceData", Method, 0, ""},
		{"(Value).IsNil", Method, 0, ""},
		{"(Value).IsValid", Method, 0, ""},
		{"(Value).IsZero", Method, 13, ""},
		{"(Value).Kind", Method, 0, ""},
		{"(Value).Len", Method, 0, ""},
		{"(Value).MapIndex", Method, 0, ""},
		{"(Value).MapKeys", Method, 0, ""},
		{"(Value).MapRange", Method, 12, ""},
		{"(Value).Method", Method, 0, ""},
		{"(Value).MethodByName", Method, 0, ""},
		{"(Value).Methods", Method, 26, ""},
		{"(Value).NumField", Method, 0, ""},
		{"(Value).NumMethod", Method, 0, ""},
		{"(Value).OverflowComplex", Method, 0, ""},
		{"(Value).OverflowFloat", Method, 0, ""},
		{"(Value).OverflowInt", Method, 0, ""},
		{"(Value).OverflowUint", Method, 0, ""},
		{"(Value).Pointer", Method, 0, ""},
		{"(Value).Recv", Method, 0, ""},
		{"(Value).Send", Method, 0, ""},
		{"(Value).Seq", Method, 23, ""},
		{"(Value).Seq2", Method, 23, ""},
		{"(Value).Set", Method, 0, ""},
		{"(Value).SetBool", Method, 0, ""},
		{"(Value).SetBytes", Method, 0, ""},
		{"(Value).SetCap", Method, 2, ""},
		{"(Value).SetComplex", Method, 0, ""},
		{"(Value).SetFloat", Method, 0, ""},
		{"(Value).SetInt", Method, 0, ""},
		{"(Value).SetIterKey", Method, 18, ""},
		{"(Value).SetIterValue", Method, 18, ""},
		{"(Value).SetLen", Method, 0, ""},
		{"(Value).SetMapIndex", Method, 0, ""},
		{"(Value).SetPointer", Method, 0, ""},
		{"(Value).SetString", Method, 0, ""},
		{"(Value).SetUint", Method, 0, ""},
		{"(Value).SetZero", Method, 20, ""},
		{"(Value).Slice", Method, 0, ""},
		{"(Value).Slice3", Method, 2, ""},
		{"(Value).String", Method, 0, ""},
		{"(Value).TryRecv", Method, 0, ""},
		{"(Value).TrySend", Method, 0, ""},
		{"(Value).Type", Method, 0, ""},
		{"(Value).Uint", Method, 0, ""},
		{"(Value).UnsafeAddr", Method, 0, ""},
		{"(Value).UnsafePointer", Method, 18, ""},
		{"Append", Func, 0, "func(s Value, x ...Value) Value"},
		{"AppendSlice", Func, 0, "func(s Value, t Value) Value"},
		{"Array", Const, 0, ""},
		{"ArrayOf", Func, 5, "func(length int, elem Type) Type"},
		{"Bool", Const, 0, ""},
		{"BothDir", Const, 0, ""},
		{"Chan", Const, 0, ""},
		{"ChanDir", Type, 0, ""},
		{"ChanOf", Func, 1, "func(dir ChanDir, t Type) Type"},
		{"Complex128", Const, 0, ""},
		{"Complex64", Const, 0, ""},
		{"Copy", Func, 0, "func(dst Value, src Value) int"},
		{"DeepEqual", Func, 0, "func(x any, y any) bool"},
		{"Float32", Const, 0, ""},
		{"Float64", Const, 0, ""},
		{"Func", Const, 0, ""},
		{"FuncOf", Func, 5, "func(in []Type, out []Type, variadic bool) Type"},
		{"Indirect", Func, 0, "func(v Value) Value"},
		{"Int", Const, 0, ""},
		{"Int16", Const, 0, ""},
		{"Int32", Const, 0, ""},
		{"Int64", Const, 0, ""},
		{"Int8", Const, 0, ""},
		{"Interface", Const, 0, ""},
		{"Invalid", Const, 0, ""},
		{"Kind", Type, 0, ""},
		{"MakeChan", Func, 0, "func(typ Type, buffer int) Value"},
		{"MakeFunc", Func, 1, "func(typ Type, fn func(args []Value) (results []Value)) Value"},
		{"MakeMap", Func, 0, "func(typ Type) Value"},
		{"MakeMapWithSize", Func, 9, "func(typ Type, n int) Value"},
		{"MakeSlice", Func, 0, "func(typ Type, len int, cap int) Value"},
		{"Map", Const, 0, ""},
		{"MapIter", Type, 12, ""},
		{"MapOf", Func, 1, "func(key Type, elem Type) Type"},
		{"Method", Type, 0, ""},
		{"Method.Func", Field, 0, ""},
		{"Method.Index", Field, 0, ""},
		{"Method.Name", Field, 0, ""},
		{"Method.PkgPath", Field, 0, ""},
		{"Method.Type", Field, 0, ""},
		{"New", Func, 0, "func(typ Type) Value"},
		{"NewAt", Func, 0, "func(typ Type, p unsafe.Pointer) Value"},
		{"Pointer", Const, 18, ""},
		{"PointerTo", Func, 18, "func(t Type) Type"},
		{"Ptr", Const, 0, ""},
		{"PtrTo", Func, 0, "func(t Type) Type"},
		{"RecvDir", Const, 0, ""},
		{"Select", Func, 1, "func(cases []SelectCase) (chosen int, recv Value, recvOK bool)"},
		{"SelectCase", Type, 1, ""},
		{"SelectCase.Chan", Field, 1, ""},
		{"SelectCase.Dir", Field, 1, ""},
		{"SelectCase.Send", Field, 1, ""},
		{"SelectDefault", Const, 1, ""},
		{"SelectDir", Type, 1, ""},
		{"SelectRecv", Const, 1, ""},
		{"SelectSend", Const, 1, ""},
		{"SendDir", Const, 0, ""},
		{"Slice", Const, 0, ""},
		{"SliceAt", Func, 23, "func(typ Type, p unsafe.Pointer, n int) Value"},
		{"SliceHeader", Type, 0, ""},
		{"SliceHeader.Cap", Field, 0, ""},
		{"SliceHeader.Data", Field, 0, ""},
		{"SliceHeader.Len", Field, 0, ""},
		{"SliceOf", Func, 1, "func(t Type) Type"},
		{"String", Const, 0, ""},
		{"StringHeader", Type, 0, ""},
		{"StringHeader.Data", Field, 0, ""},
		{"StringHeader.Len", Field, 0, ""},
		{"Struct", Const, 0, ""},
		{"StructField", Type, 0, ""},
		{"StructField.Anonymous", Field, 0, ""},
		{"StructField.Index", Field, 0, ""},
		{"StructField.Name", Field, 0, ""},
		{"StructField.Offset", Field, 0, ""},
		{"StructField.PkgPath", Field, 0, ""},
		{"StructField.Tag", Field, 0, ""},
		{"StructField.Type", Field, 0, ""},
		{"StructOf", Func, 7, "func(fields []StructField) Type"},
		{"StructTag", Type, 0, ""},
		{"Swapper", Func, 8, "func(slice any) func(i int, j int)"},
		{"TypeAssert", Func, 25, "func[T any](v Value) (T, bool)"},
		{"TypeFor", Func, 22, "func[T any]() Type"},
		{"TypeOf", Func, 0, "func(i any) Type"},
		{"Uint", Const, 0, ""},
		{"Uint16", Const, 0, ""},
		{"Uint32", Const, 0, ""},
		{"Uint64", Const, 0, ""},
		{"Uint8", Const, 0, ""},
		{"Uintptr", Const, 0, ""},
		{"UnsafePointer", Const, 0, ""},
		{"Value", Type, 0, ""},
		{"ValueError", Type, 0, ""},
		{"ValueError.Kind", Field, 0, ""},
		{"ValueError.Method", Field, 0, ""},
		{"ValueOf", Func, 0, "func(i any) Value"},
		{"VisibleFields", Func, 17, "func(t Type) []StructField"},
		{"Zero", Func, 0, "func(typ Type) Value"},
	},
	"regexp": {
		{"(*Regexp).AppendText", Method, 24, ""},
		{"(*Regexp).Copy", Method, 6, ""},
		{"(*Regexp).Expand", Method, 0, ""},
		{"(*Regexp).ExpandString", Method, 0, ""},
		{"(*Regexp).Find", Method, 0, ""},
		{"(*Regexp).FindAll", Method, 0, ""},
		{"(*Regexp).FindAllIndex", Method, 0, ""},
		{"(*Regexp).FindAllString", Method, 0, ""},
		{"(*Regexp).FindAllStringIndex", Method, 0, ""},
		{"(*Regexp).FindAllStringSubmatch", Method, 0, ""},
		{"(*Regexp).FindAllStringSubmatchIndex", Method, 0, ""},
		{"(*Regexp).FindAllSubmatch", Method, 0, ""},
		{"(*Regexp).FindAllSubmatchIndex", Method, 0, ""},
		{"(*Regexp).FindIndex", Method, 0, ""},
		{"(*Regexp).FindReaderIndex", Method, 0, ""},
		{"(*Regexp).FindReaderSubmatchIndex", Method, 0, ""},
		{"(*Regexp).FindString", Method, 0, ""},
		{"(*Regexp).FindStringIndex", Method, 0, ""},
		{"(*Regexp).FindStringSubmatch", Method, 0, ""},
		{"(*Regexp).FindStringSubmatchIndex", Method, 0, ""},
		{"(*Regexp).FindSubmatch", Method, 0, ""},
		{"(*Regexp).FindSubmatchIndex", Method, 0, ""},
		{"(*Regexp).LiteralPrefix", Method, 0, ""},
		{"(*Regexp).Longest", Method, 1, ""},
		{"(*Regexp).MarshalText", Method, 21, ""},
		{"(*Regexp).Match", Method, 0, ""},
		{"(*Regexp).MatchReader", Method, 0, ""},
		{"(*Regexp).MatchString", Method, 0, ""},
		{"(*Regexp).NumSubexp", Method, 0, ""},
		{"(*Regexp).ReplaceAll", Method, 0, ""},
		{"(*Regexp).ReplaceAllFunc", Method, 0, ""},
		{"(*Regexp).ReplaceAllLiteral", Method, 0, ""},
		{"(*Regexp).ReplaceAllLiteralString", Method, 0, ""},
		{"(*Regexp).ReplaceAllString", Method, 0, ""},
		{"(*Regexp).ReplaceAllStringFunc", Method, 0, ""},
		{"(*Regexp).Split", Method, 1, ""},
		{"(*Regexp).String", Method, 0, ""},
		{"(*Regexp).SubexpIndex", Method, 15, ""},
		{"(*Regexp).SubexpNames", Method, 0, ""},
		{"(*Regexp).UnmarshalText", Method, 21, ""},
		{"Compile", Func, 0, "func(expr string) (*Regexp, error)"},
		{"CompilePOSIX", Func, 0, "func(expr string) (*Regexp, error)"},
		{"Match", Func, 0, "func(pattern string, b []byte) (matched bool, err error)"},
		{"MatchReader", Func, 0, "func(pattern string, r io.RuneReader) (matched bool, err error)"},
		{"MatchString", Func, 0, "func(pattern string, s string) (matched bool, err error)"},
		{"MustCompile", Func, 0, "func(str string) *Regexp"},
		{"MustCompilePOSIX", Func, 0, "func(str string) *Regexp"},
		{"QuoteMeta", Func, 0, "func(s string) string"},
		{"Regexp", Type, 0, ""},
	},
	"regexp/syntax": {
		{"(*Error).Error", Method, 0, ""},
		{"(*Inst).MatchEmptyWidth", Method, 0, ""},
		{"(*Inst).MatchRune", Method, 0, ""},
		{"(*Inst).MatchRunePos", Method, 3, ""},
		{"(*Inst).String", Method, 0, ""},
		{"(*Prog).Prefix", Method, 0, ""},
		{"(*Prog).StartCond", Method, 0, ""},
		{"(*Prog).String", Method, 0, ""},
		{"(*Regexp).CapNames", Method, 0, ""},
		{"(*Regexp).Equal", Method, 0, ""},
		{"(*Regexp).MaxCap", Method, 0, ""},
		{"(*Regexp).Simplify", Method, 0, ""},
		{"(*Regexp).String", Method, 0, ""},
		{"(ErrorCode).String", Method, 0, ""},
		{"(InstOp).String", Method, 3, ""},
		{"(Op).String", Method, 11, ""},
		{"ClassNL", Const, 0, ""},
		{"Compile", Func, 0, "func(re *Regexp) (*Prog, error)"},
		{"DotNL", Const, 0, ""},
		{"EmptyBeginLine", Const, 0, ""},
		{"EmptyBeginText", Const, 0, ""},
		{"EmptyEndLine", Const, 0, ""},
		{"EmptyEndText", Const, 0, ""},
		{"EmptyNoWordBoundary", Const, 0, ""},
		{"EmptyOp", Type, 0, ""},
		{"EmptyOpContext", Func, 0, "func(r1 rune, r2 rune) EmptyOp"},
		{"EmptyWordBoundary", Const, 0, ""},
		{"ErrInternalError", Const, 0, ""},
		{"ErrInvalidCharClass", Const, 0, ""},
		{"ErrInvalidCharRange", Const, 0, ""},
		{"ErrInvalidEscape", Const, 0, ""},
		{"ErrInvalidNamedCapture", Const, 0, ""},
		{"ErrInvalidPerlOp", Const, 0, ""},
		{"ErrInvalidRepeatOp", Const, 0, ""},
		{"ErrInvalidRepeatSize", Const, 0, ""},
		{"ErrInvalidUTF8", Const, 0, ""},
		{"ErrLarge", Const, 20, ""},
		{"ErrMissingBracket", Const, 0, ""},
		{"ErrMissingParen", Const, 0, ""},
		{"ErrMissingRepeatArgument", Const, 0, ""},
		{"ErrNestingDepth", Const, 19, ""},
		{"ErrTrailingBackslash", Const, 0, ""},
		{"ErrUnexpectedParen", Const, 1, ""},
		{"Error", Type, 0, ""},
		{"Error.Code", Field, 0, ""},
		{"Error.Expr", Field, 0, ""},
		{"ErrorCode", Type, 0, ""},
		{"Flags", Type, 0, ""},
		{"FoldCase", Const, 0, ""},
		{"Inst", Type, 0, ""},
		{"Inst.Arg", Field, 0, ""},
		{"Inst.Op", Field, 0, ""},
		{"Inst.Out", Field, 0, ""},
		{"Inst.Rune", Field, 0, ""},
		{"InstAlt", Const, 0, ""},
		{"InstAltMatch", Const, 0, ""},
		{"InstCapture", Const, 0, ""},
		{"InstEmptyWidth", Const, 0, ""},
		{"InstFail", Const, 0, ""},
		{"InstMatch", Const, 0, ""},
		{"InstNop", Const, 0, ""},
		{"InstOp", Type, 0, ""},
		{"InstRune", Const, 0, ""},
		{"InstRune1", Const, 0, ""},
		{"InstRuneAny", Const, 0, ""},
		{"InstRuneAnyNotNL", Const, 0, ""},
		{"IsWordChar", Func, 0, "func(r rune) bool"},
		{"Literal", Const, 0, ""},
		{"MatchNL", Const, 0, ""},
		{"NonGreedy", Const, 0, ""},
		{"OneLine", Const, 0, ""},
		{"Op", Type, 0, ""},
		{"OpAlternate", Const, 0, ""},
		{"OpAnyChar", Const, 0, ""},
		{"OpAnyCharNotNL", Const, 0, ""},
		{"OpBeginLine", Const, 0, ""},
		{"OpBeginText", Const, 0, ""},
		{"OpCapture", Const, 0, ""},
		{"OpCharClass", Const, 0, ""},
		{"OpConcat", Const, 0, ""},
		{"OpEmptyMatch", Const, 0, ""},
		{"OpEndLine", Const, 0, ""},
		{"OpEndText", Const, 0, ""},
		{"OpLiteral", Const, 0, ""},
		{"OpNoMatch", Const, 0, ""},
		{"OpNoWordBoundary", Const, 0, ""},
		{"OpPlus", Const, 0, ""},
		{"OpQuest", Const, 0, ""},
		{"OpRepeat", Const, 0, ""},
		{"OpStar", Const, 0, ""},
		{"OpWordBoundary", Const, 0, ""},
		{"POSIX", Const, 0, ""},
		{"Parse", Func, 0, "func(s string, flags Flags) (*Regexp, error)"},
		{"Perl", Const, 0, ""},
		{"PerlX", Const, 0, ""},
		{"Prog", Type, 0, ""},
		{"Prog.Inst", Field, 0, ""},
		{"Prog.NumCap", Field, 0, ""},
		{"Prog.Start", Field, 0, ""},
		{"Regexp", Type, 0, ""},
		{"Regexp.Cap", Field, 0, ""},
		{"Regexp.Flags", Field, 0, ""},
		{"Regexp.Max", Field, 0, ""},
		{"Regexp.Min", Field, 0, ""},
		{"Regexp.Name", Field, 0, ""},
		{"Regexp.Op", Field, 0, ""},
		{"Regexp.Rune", Field, 0, ""},
		{"Regexp.Rune0", Field, 0, ""},
		{"Regexp.Sub", Field, 0, ""},
		{"Regexp.Sub0", Field, 0, ""},
		{"Simple", Const, 0, ""},
		{"UnicodeGroups", Const, 0, ""},
		{"WasDollar", Const, 0, ""},
	},
	"runtime": {
		{"(*BlockProfileRecord).Stack", Method, 1, ""},
		{"(*Frames).Next", Method, 7, ""},
		{"(*Func).Entry", Method, 0, ""},
		{"(*Func).FileLine", Method, 0, ""},
		{"(*Func).Name", Method, 0, ""},
		{"(*MemProfileRecord).InUseBytes", Method, 0, ""},
		{"(*MemProfileRecord).InUseObjects", Method, 0, ""},
		{"(*MemProfileRecord).Stack", Method, 0, ""},
		{"(*PanicNilError).Error", Method, 21, ""},
		{"(*PanicNilError).RuntimeError", Method, 21, ""},
		{"(*Pinner).Pin", Method, 21, ""},
		{"(*Pinner).Unpin", Method, 21, ""},
		{"(*StackRecord).Stack", Method, 0, ""},
		{"(*TypeAssertionError).Error", Method, 0, ""},
		{"(*TypeAssertionError).RuntimeError", Method, 0, ""},
		{"(Cleanup).Stop", Method, 24, ""},
		{"(Error).Error", Method, 0, ""},
		{"(Error).RuntimeError", Method, 0, ""},
		{"AddCleanup", Func, 24, "func[T, S any](ptr *T, cleanup func(S), arg S) Cleanup"},
		{"BlockProfile", Func, 1, "func(p []BlockProfileRecord) (n int, ok bool)"},
		{"BlockProfileRecord", Type, 1, ""},
		{"BlockProfileRecord.Count", Field, 1, ""},
		{"BlockProfileRecord.Cycles", Field, 1, ""},
		{"BlockProfileRecord.StackRecord", Field, 1, ""},
		{"Breakpoint", Func, 0, "func()"},
		{"CPUProfile", Func, 0, "func() []byte"},
		{"Caller", Func, 0, "func(skip int) (pc uintptr, file string, line int, ok bool)"},
		{"Callers", Func, 0, "func(skip int, pc []uintptr) int"},
		{"CallersFrames", Func, 7, "func(callers []uintptr) *Frames"},
		{"Cleanup", Type, 24, ""},
		{"Compiler", Const, 0, ""},
		{"Error", Type, 0, ""},
		{"Frame", Type, 7, ""},
		{"Frame.Entry", Field, 7, ""},
		{"Frame.File", Field, 7, ""},
		{"Frame.Func", Field, 7, ""},
		{"Frame.Function", Field, 7, ""},
		{"Frame.Line", Field, 7, ""},
		{"Frame.PC", Field, 7, ""},
		{"Frames", Type, 7, ""},
		{"Func", Type, 0, ""},
		{"FuncForPC", Func, 0, "func(pc uintptr) *Func"},
		{"GC", Func, 0, "func()"},
		{"GOARCH", Const, 0, ""},
		{"GOMAXPROCS", Func, 0, "func(n int) int"},
		{"GOOS", Const, 0, ""},
		{"GOROOT", Func, 0, "func() string"},
		{"Goexit", Func, 0, "func()"},
		{"GoroutineProfile", Func, 0, "func(p []StackRecord) (n int, ok bool)"},
		{"Gosched", Func, 0, "func()"},
		{"KeepAlive", Func, 7, "func(x any)"},
		{"LockOSThread", Func, 0, "func()"},
		{"MemProfile", Func, 0, "func(p []MemProfileRecord, inuseZero bool) (n int, ok bool)"},
		{"MemProfileRate", Var, 0, ""},
		{"MemProfileRecord", Type, 0, ""},
		{"MemProfileRecord.AllocBytes", Field, 0, ""},
		{"MemProfileRecord.AllocObjects", Field, 0, ""},
		{"MemProfileRecord.FreeBytes", Field, 0, ""},
		{"MemProfileRecord.FreeObjects", Field, 0, ""},
		{"MemProfileRecord.Stack0", Field, 0, ""},
		{"MemStats", Type, 0, ""},
		{"MemStats.Alloc", Field, 0, ""},
		{"MemStats.BuckHashSys", Field, 0, ""},
		{"MemStats.BySize", Field, 0, ""},
		{"MemStats.DebugGC", Field, 0, ""},
		{"MemStats.EnableGC", Field, 0, ""},
		{"MemStats.Frees", Field, 0, ""},
		{"MemStats.GCCPUFraction", Field, 5, ""},
		{"MemStats.GCSys", Field, 2, ""},
		{"MemStats.HeapAlloc", Field, 0, ""},
		{"MemStats.HeapIdle", Field, 0, ""},
		{"MemStats.HeapInuse", Field, 0, ""},
		{"MemStats.HeapObjects", Field, 0, ""},
		{"MemStats.HeapReleased", Field, 0, ""},
		{"MemStats.HeapSys", Field, 0, ""},
		{"MemStats.LastGC", Field, 0, ""},
		{"MemStats.Lookups", Field, 0, ""},
		{"MemStats.MCacheInuse", Field, 0, ""},
		{"MemStats.MCacheSys", Field, 0, ""},
		{"MemStats.MSpanInuse", Field, 0, ""},
		{"MemStats.MSpanSys", Field, 0, ""},
		{"MemStats.Mallocs", Field, 0, ""},
		{"MemStats.NextGC", Field, 0, ""},
		{"MemStats.NumForcedGC", Field, 8, ""},
		{"MemStats.NumGC", Field, 0, ""},
		{"MemStats.OtherSys", Field, 2, ""},
		{"MemStats.PauseEnd", Field, 4, ""},
		{"MemStats.PauseNs", Field, 0, ""},
		{"MemStats.PauseTotalNs", Field, 0, ""},
		{"MemStats.StackInuse", Field, 0, ""},
		{"MemStats.StackSys", Field, 0, ""},
		{"MemStats.Sys", Field, 0, ""},
		{"MemStats.TotalAlloc", Field, 0, ""},
		{"MutexProfile", Func, 8, "func(p []BlockProfileRecord) (n int, ok bool)"},
		{"NumCPU", Func, 0, "func() int"},
		{"NumCgoCall", Func, 0, "func() int64"},
		{"NumGoroutine", Func, 0, "func() int"},
		{"PanicNilError", Type, 21, ""},
		{"Pinner", Type, 21, ""},
		{"ReadMemStats", Func, 0, "func(m *MemStats)"},
		{"ReadTrace", Func, 5, "func() (buf []byte)"},
		{"SetBlockProfileRate", Func, 1, "func(rate int)"},
		{"SetCPUProfileRate", Func, 0, "func(hz int)"},
		{"SetCgoTraceback", Func, 7, "func(version int, traceback unsafe.Pointer, context unsafe.Pointer, symbolizer unsafe.Pointer)"},
		{"SetDefaultGOMAXPROCS", Func, 25, "func()"},
		{"SetFinalizer", Func, 0, "func(obj any, finalizer any)"},
		{"SetMutexProfileFraction", Func, 8, "func(rate int) int"},
		{"Stack", Func, 0, "func(buf []byte, all bool) int"},
		{"StackRecord", Type, 0, ""},
		{"StackRecord.Stack0", Field, 0, ""},
		{"StartTrace", Func, 5, "func() error"},
		{"StopTrace", Func, 5, "func()"},
		{"ThreadCreateProfile", Func, 0, "func(p []StackRecord) (n int, ok bool)"},
		{"TypeAssertionError", Type, 0, ""},
		{"UnlockOSThread", Func, 0, "func()"},
		{"Version", Func, 0, "func() string"},
	},
	"runtime/cgo": {
		{"(Handle).Delete", Method, 17, ""},
		{"(Handle).Value", Method, 17, ""},
		{"Handle", Type, 17, ""},
		{"Incomplete", Type, 20, ""},
		{"NewHandle", Func, 17, ""},
	},
	"runtime/coverage": {
		{"ClearCounters", Func, 20, "func() error"},
		{"WriteCounters", Func, 20, "func(w io.Writer) error"},
		{"WriteCountersDir", Func, 20, "func(dir string) error"},
		{"WriteMeta", Func, 20, "func(w io.Writer) error"},
		{"WriteMetaDir", Func, 20, "func(dir string) error"},
	},
	"runtime/debug": {
		{"(*BuildInfo).String", Method, 18, ""},
		{"BuildInfo", Type, 12, ""},
		{"BuildInfo.Deps", Field, 12, ""},
		{"BuildInfo.GoVersion", Field, 18, ""},
		{"BuildInfo.Main", Field, 12, ""},
		{"BuildInfo.Path", Field, 12, ""},
		{"BuildInfo.Settings", Field, 18, ""},
		{"BuildSetting", Type, 18, ""},
		{"BuildSetting.Key", Field, 18, ""},
		{"BuildSetting.Value", Field, 18, ""},
		{"CrashOptions", Type, 23, ""},
		{"FreeOSMemory", Func, 1, "func()"},
		{"GCStats", Type, 1, ""},
		{"GCStats.LastGC", Field, 1, ""},
		{"GCStats.NumGC", Field, 1, ""},
		{"GCStats.Pause", Field, 1, ""},
		{"GCStats.PauseEnd", Field, 4, ""},
		{"GCStats.PauseQuantiles", Field, 1, ""},
		{"GCStats.PauseTotal", Field, 1, ""},
		{"Module", Type, 12, ""},
		{"Module.Path", Field, 12, ""},
		{"Module.Replace", Field, 12, ""},
		{"Module.Sum", Field, 12, ""},
		{"Module.Version", Field, 12, ""},
		{"ParseBuildInfo", Func, 18, "func(data string) (bi *BuildInfo, err error)"},
		{"PrintStack", Func, 0, "func()"},
		{"ReadBuildInfo", Func, 12, "func() (info *BuildInfo, ok bool)"},
		{"ReadGCStats", Func, 1, "func(stats *GCStats)"},
		{"SetCrashOutput", Func, 23, "func(f *os.File, opts CrashOptions) error"},
		{"SetGCPercent", Func, 1, "func(percent int) int"},
		{"SetMaxStack", Func, 2, "func(bytes int) int"},
		{"SetMaxThreads", Func, 2, "func(threads int) int"},
		{"SetMemoryLimit", Func, 19, "func(limit int64) int64"},
		{"SetPanicOnFault", Func, 3, "func(enabled bool) bool"},
		{"SetTraceback", Func, 6, "func(level string)"},
		{"Stack", Func, 0, "func() []byte"},
		{"WriteHeapDump", Func, 3, "func(fd uintptr)"},
	},
	"runtime/metrics": {
		{"(Value).Float64", Method, 16, ""},
		{"(Value).Float64Histogram", Method, 16, ""},
		{"(Value).Kind", Method, 16, ""},
		{"(Value).Uint64", Method, 16, ""},
		{"All", Func, 16, "func() []Description"},
		{"Description", Type, 16, ""},
		{"Description.Cumulative", Field, 16, ""},
		{"Description.Description", Field, 16, ""},
		{"Description.Kind", Field, 16, ""},
		{"Description.Name", Field, 16, ""},
		{"Float64Histogram", Type, 16, ""},
		{"Float64Histogram.Buckets", Field, 16, ""},
		{"Float64Histogram.Counts", Field, 16, ""},
		{"KindBad", Const, 16, ""},
		{"KindFloat64", Const, 16, ""},
		{"KindFloat64Histogram", Const, 16, ""},
		{"KindUint64", Const, 16, ""},
		{"Read", Func, 16, "func(m []Sample)"},
		{"Sample", Type, 16, ""},
		{"Sample.Name", Field, 16, ""},
		{"Sample.Value", Field, 16, ""},
		{"Value", Type, 16, ""},
		{"ValueKind", Type, 16, ""},
	},
	"runtime/pprof": {
		{"(*Profile).Add", Method, 0, ""},
		{"(*Profile).Count", Method, 0, ""},
		{"(*Profile).Name", Method, 0, ""},
		{"(*Profile).Remove", Method, 0, ""},
		{"(*Profile).WriteTo", Method, 0, ""},
		{"Do", Func, 9, "func(ctx context.Context, labels LabelSet, f func(context.Context))"},
		{"ForLabels", Func, 9, "func(ctx context.Context, f func(key string, value string) bool)"},
		{"Label", Func, 9, "func(ctx context.Context, key string) (string, bool)"},
		{"LabelSet", Type, 9, ""},
		{"Labels", Func, 9, "func(args ...string) LabelSet"},
		{"Lookup", Func, 0, "func(name string) *Profile"},
		{"NewProfile", Func, 0, "func(name string) *Profile"},
		{"Profile", Type, 0, ""},
		{"Profiles", Func, 0, "func() []*Profile"},
		{"SetGoroutineLabels", Func, 9, "func(ctx context.Context)"},
		{"StartCPUProfile", Func, 0, "func(w io.Writer) error"},
		{"StopCPUProfile", Func, 0, "func()"},
		{"WithLabels", Func, 9, "func(ctx context.Context, labels LabelSet) context.Context"},
		{"WriteHeapProfile", Func, 0, "func(w io.Writer) error"},
	},
	"runtime/trace": {
		{"(*FlightRecorder).Enabled", Method, 25, ""},
		{"(*FlightRecorder).Start", Method, 25, ""},
		{"(*FlightRecorder).Stop", Method, 25, ""},
		{"(*FlightRecorder).WriteTo", Method, 25, ""},
		{"(*Region).End", Method, 11, ""},
		{"(*Task).End", Method, 11, ""},
		{"FlightRecorder", Type, 25, ""},
		{"FlightRecorderConfig", Type, 25, ""},
		{"FlightRecorderConfig.MaxBytes", Field, 25, ""},
		{"FlightRecorderConfig.MinAge", Field, 25, ""},
		{"IsEnabled", Func, 11, "func() bool"},
		{"Log", Func, 11, "func(ctx context.Context, category string, message string)"},
		{"Logf", Func, 11, "func(ctx context.Context, category string, format string, args ...any)"},
		{"NewFlightRecorder", Func, 25, "func(cfg FlightRecorderConfig) *FlightRecorder"},
		{"NewTask", Func, 11, "func(pctx context.Context, taskType string) (ctx context.Context, task *Task)"},
		{"Region", Type, 11, ""},
		{"Start", Func, 5, "func(w io.Writer) error"},
		{"StartRegion", Func, 11, "func(ctx context.Context, regionType string) *Region"},
		{"Stop", Func, 5, "func()"},
		{"Task", Type, 11, ""},
		{"WithRegion", Func, 11, "func(ctx context.Context, regionType string, fn func())"},
	},
	"slices": {
		{"All", Func, 23, "func[Slice ~[]E, E any](s Slice) iter.Seq2[int, E]"},
		{"AppendSeq", Func, 23, "func[Slice ~[]E, E any](s Slice, seq iter.Seq[E]) Slice"},
		{"Backward", Func, 23, "func[Slice ~[]E, E any](s Slice) iter.Seq2[int, E]"},
		{"BinarySearch", Func, 21, "func[S ~[]E, E cmp.Ordered](x S, target E) (int, bool)"},
		{"BinarySearchFunc", Func, 21, "func[S ~[]E, E, T any](x S, target T, cmp func(E, T) int) (int, bool)"},
		{"Chunk", Func, 23, "func[Slice ~[]E, E any](s Slice, n int) iter.Seq[Slice]"},
		{"Clip", Func, 21, "func[S ~[]E, E any](s S) S"},
		{"Clone", Func, 21, "func[S ~[]E, E any](s S) S"},
		{"Collect", Func, 23, "func[E any](seq iter.Seq[E]) []E"},
		{"Compact", Func, 21, "func[S ~[]E, E comparable](s S) S"},
		{"CompactFunc", Func, 21, "func[S ~[]E, E any](s S, eq func(E, E) bool) S"},
		{"Compare", Func, 21, "func[S ~[]E, E cmp.Ordered](s1 S, s2 S) int"},
		{"CompareFunc", Func, 21, "func[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, cmp func(E1, E2) int) int"},
		{"Concat", Func, 22, "func[S ~[]E, E any](slices ...S) S"},
		{"Contains", Func, 21, "func[S ~[]E, E comparable](s S, v E) bool"},
		{"ContainsFunc", Func, 21, "func[S ~[]E, E any](s S, f func(E) bool) bool"},
		{"Delete", Func, 21, "func[S ~[]E, E any](s S, i int, j int) S"},
		{"DeleteFunc", Func, 21, "func[S ~[]E, E any](s S, del func(E) bool) S"},
		{"Equal", Func, 21, "func[S ~[]E, E comparable](s1 S, s2 S) bool"},
		{"EqualFunc", Func, 21, "func[S1 ~[]E1, S2 ~[]E2, E1, E2 any](s1 S1, s2 S2, eq func(E1, E2) bool) bool"},
		{"Grow", Func, 21, "func[S ~[]E, E any](s S, n int) S"},
		{"Index", Func, 21, "func[S ~[]E, E comparable](s S, v E) int"},
		{"IndexFunc", Func, 21, "func[S ~[]E, E any](s S, f func(E) bool) int"},
		{"Insert", Func, 21, "func[S ~[]E, E any](s S, i int, v ...E) S"},
		{"IsSorted", Func, 21, "func[S ~[]E, E cmp.Ordered](x S) bool"},
		{"IsSortedFunc", Func, 21, "func[S ~[]E, E any](x S, cmp func(a E, b E) int) bool"},
		{"Max", Func, 21, "func[S ~[]E, E cmp.Ordered](x S) E"},
		{"MaxFunc", Func, 21, "func[S ~[]E, E any](x S, cmp func(a E, b E) int) E"},
		{"Min", Func, 21, "func[S ~[]E, E cmp.Ordered](x S) E"},
		{"MinFunc", Func, 21, "func[S ~[]E, E any](x S, cmp func(a E, b E) int) E"},
		{"Repeat", Func, 23, "func[S ~[]E, E any](x S, count int) S"},
		{"Replace", Func, 21, "func[S ~[]E, E any](s S, i int, j int, v ...E) S"},
		{"Reverse", Func, 21, "func[S ~[]E, E any](s S)"},
		{"Sort", Func, 21, "func[S ~[]E, E cmp.Ordered](x S)"},
		{"SortFunc", Func, 21, "func[S ~[]E, E any](x S, cmp func(a E, b E) int)"},
		{"SortStableFunc", Func, 21, "func[S ~[]E, E any](x S, cmp func(a E, b E) int)"},
		{"Sorted", Func, 23, "func[E cmp.Ordered](seq iter.Seq[E]) []E"},
		{"SortedFunc", Func, 23, "func[E any](seq iter.Seq[E], cmp func(E, E) int) []E"},
		{"SortedStableFunc", Func, 23, "func[E any](seq iter.Seq[E], cmp func(E, E) int) []E"},
		{"Values", Func, 23, "func[Slice ~[]E, E any](s Slice) iter.Seq[E]"},
	},
	"sort": {
		{"(Float64Slice).Len", Method, 0, ""},
		{"(Float64Slice).Less", Method, 0, ""},
		{"(Float64Slice).Search", Method, 0, ""},
		{"(Float64Slice).Sort", Method, 0, ""},
		{"(Float64Slice).Swap", Method, 0, ""},
		{"(IntSlice).Len", Method, 0, ""},
		{"(IntSlice).Less", Method, 0, ""},
		{"(IntSlice).Search", Method, 0, ""},
		{"(IntSlice).Sort", Method, 0, ""},
		{"(IntSlice).Swap", Method, 0, ""},
		{"(Interface).Len", Method, 0, ""},
		{"(Interface).Less", Method, 0, ""},
		{"(Interface).Swap", Method, 0, ""},
		{"(StringSlice).Len", Method, 0, ""},
		{"(StringSlice).Less", Method, 0, ""},
		{"(StringSlice).Search", Method, 0, ""},
		{"(StringSlice).Sort", Method, 0, ""},
		{"(StringSlice).Swap", Method, 0, ""},
		{"Find", Func, 19, "func(n int, cmp func(int) int) (i int, found bool)"},
		{"Float64Slice", Type, 0, ""},
		{"Float64s", Func, 0, "func(x []float64)"},
		{"Float64sAreSorted", Func, 0, "func(x []float64) bool"},
		{"IntSlice", Type, 0, ""},
		{"Interface", Type, 0, ""},
		{"Ints", Func, 0, "func(x []int)"},
		{"IntsAreSorted", Func, 0, "func(x []int) bool"},
		{"IsSorted", Func, 0, "func(data Interface) bool"},
		{"Reverse", Func, 1, "func(data Interface) Interface"},
		{"Search", Func, 0, "func(n int, f func(int) bool) int"},
		{"SearchFloat64s", Func, 0, "func(a []float64, x float64) int"},
		{"SearchInts", Func, 0, "func(a []int, x int) int"},
		{"SearchStrings", Func, 0, "func(a []string, x string) int"},
		{"Slice", Func, 8, "func(x any, less func(i int, j int) bool)"},
		{"SliceIsSorted", Func, 8, "func(x any, less func(i int, j int) bool) bool"},
		{"SliceStable", Func, 8, "func(x any, less func(i int, j int) bool)"},
		{"Sort", Func, 0, "func(data Interface)"},
		{"Stable", Func, 2, "func(data Interface)"},
		{"StringSlice", Type, 0, ""},
		{"Strings", Func, 0, "func(x []string)"},
		{"StringsAreSorted", Func, 0, "func(x []string) bool"},
	},
	"strconv": {
		{"(*NumError).Error", Method, 0, ""},
		{"(*NumError).Unwrap", Method, 14, ""},
		{"AppendBool", Func, 0, "func(dst []byte, b bool) []byte"},
		{"AppendFloat", Func, 0, "func(dst []byte, f float64, fmt byte, prec int, bitSize int) []byte"},
		{"AppendInt", Func, 0, "func(dst []byte, i int64, base int) []byte"},
		{"AppendQuote", Func, 0, "func(dst []byte, s string) []byte"},
		{"AppendQuoteRune", Func, 0, "func(dst []byte, r rune) []byte"},
		{"AppendQuoteRuneToASCII", Func, 0, "func(dst []byte, r rune) []byte"},
		{"AppendQuoteRuneToGraphic", Func, 6, "func(dst []byte, r rune) []byte"},
		{"AppendQuoteToASCII", Func, 0, "func(dst []byte, s string) []byte"},
		{"AppendQuoteToGraphic", Func, 6, "func(dst []byte, s string) []byte"},
		{"AppendUint", Func, 0, "func(dst []byte, i uint64, base int) []byte"},
		{"Atoi", Func, 0, "func(s string) (int, error)"},
		{"CanBackquote", Func, 0, "func(s string) bool"},
		{"ErrRange", Var, 0, ""},
		{"ErrSyntax", Var, 0, ""},
		{"FormatBool", Func, 0, "func(b bool) string"},
		{"FormatComplex", Func, 15, "func(c complex128, fmt byte, prec int, bitSize int) string"},
		{"FormatFloat", Func, 0, "func(f float64, fmt byte, prec int, bitSize int) string"},
		{"FormatInt", Func, 0, "func(i int64, base int) string"},
		{"FormatUint", Func, 0, "func(i uint64, base int) string"},
		{"IntSize", Const, 0, ""},
		{"IsGraphic", Func, 6, "func(r rune) bool"},
		{"IsPrint", Func, 0, "func(r rune) bool"},
		{"Itoa", Func, 0, "func(i int) string"},
		{"NumError", Type, 0, ""},
		{"NumError.Err", Field, 0, ""},
		{"NumError.Func", Field, 0, ""},
		{"NumError.Num", Field, 0, ""},
		{"ParseBool", Func, 0, "func(str string) (bool, error)"},
		{"ParseComplex", Func, 15, "func(s string, bitSize int) (complex128, error)"},
		{"ParseFloat", Func, 0, "func(s string, bitSize int) (float64, error)"},
		{"ParseInt", Func, 0, "func(s string, base int, bitSize int) (i int64, err error)"},
		{"ParseUint", Func, 0, "func(s string, base int, bitSize int) (uint64, error)"},
		{"Quote", Func, 0, "func(s string) string"},
		{"QuoteRune", Func, 0, "func(r rune) string"},
		{"QuoteRuneToASCII", Func, 0, "func(r rune) string"},
		{"QuoteRuneToGraphic", Func, 6, "func(r rune) string"},
		{"QuoteToASCII", Func, 0, "func(s string) string"},
		{"QuoteToGraphic", Func, 6, "func(s string) string"},
		{"QuotedPrefix", Func, 17, "func(s string) (string, error)"},
		{"Unquote", Func, 0, "func(s string) (string, error)"},
		{"UnquoteChar", Func, 0, "func(s string, quote byte) (value rune, multibyte bool, tail string, err error)"},
	},
	"strings": {
		{"(*Builder).Cap", Method, 12, ""},
		{"(*Builder).Grow", Method, 10, ""},
		{"(*Builder).Len", Method, 10, ""},
		{"(*Builder).Reset", Method, 10, ""},
		{"(*Builder).String", Method, 10, ""},
		{"(*Builder).Write", Method, 10, ""},
		{"(*Builder).WriteByte", Method, 10, ""},
		{"(*Builder).WriteRune", Method, 10, ""},
		{"(*Builder).WriteString", Method, 10, ""},
		{"(*Reader).Len", Method, 0, ""},
		{"(*Reader).Read", Method, 0, ""},
		{"(*Reader).ReadAt", Method, 0, ""},
		{"(*Reader).ReadByte", Method, 0, ""},
		{"(*Reader).ReadRune", Method, 0, ""},
		{"(*Reader).Reset", Method, 7, ""},
		{"(*Reader).Seek", Method, 0, ""},
		{"(*Reader).Size", Method, 5, ""},
		{"(*Reader).UnreadByte", Method, 0, ""},
		{"(*Reader).UnreadRune", Method, 0, ""},
		{"(*Reader).WriteTo", Method, 1, ""},
		{"(*Replacer).Replace", Method, 0, ""},
		{"(*Replacer).WriteString", Method, 0, ""},
		{"Builder", Type, 10, ""},
		{"Clone", Func, 18, "func(s string) string"},
		{"Compare", Func, 5, "func(a string, b string) int"},
		{"Contains", Func, 0, "func(s string, substr string) bool"},
		{"ContainsAny", Func, 0, "func(s string, chars string) bool"},
		{"ContainsFunc", Func, 21, "func(s string, f func(rune) bool) bool"},
		{"ContainsRune", Func, 0, "func(s string, r rune) bool"},
		{"Count", Func, 0, "func(s string, substr string) int"},
		{"Cut", Func, 18, "func(s string, sep string) (before string, after string, found bool)"},
		{"CutPrefix", Func, 20, "func(s string, prefix string) (after string, found bool)"},
		{"CutSuffix", Func, 20, "func(s string, suffix string) (before string, found bool)"},
		{"EqualFold", Func, 0, "func(s string, t string) bool"},
		{"Fields", Func, 0, "func(s string) []string"},
		{"FieldsFunc", Func, 0, "func(s string, f func(rune) bool) []string"},
		{"FieldsFuncSeq", Func, 24, "func(s string, f func(rune) bool) iter.Seq[string]"},
		{"FieldsSeq", Func, 24, "func(s string) iter.Seq[string]"},
		{"HasPrefix", Func, 0, "func(s string, prefix string) bool"},
		{"HasSuffix", Func, 0, "func(s string, suffix string) bool"},
		{"Index", Func, 0, "func(s string, substr string) int"},
		{"IndexAny", Func, 0, "func(s string, chars string) int"},
		{"IndexByte", Func, 2, "func(s string, c byte) int"},
		{"IndexFunc", Func, 0, "func(s string, f func(rune) bool) int"},
		{"IndexRune", Func, 0, "func(s string, r rune) int"},
		{"Join", Func, 0, "func(elems []string, sep string) string"},
		{"LastIndex", Func, 0, "func(s string, substr string) int"},
		{"LastIndexAny", Func, 0, "func(s string, chars string) int"},
		{"LastIndexByte", Func, 5, "func(s string, c byte) int"},
		{"LastIndexFunc", Func, 0, "func(s string, f func(rune) bool) int"},
		{"Lines", Func, 24, "func(s string) iter.Seq[string]"},
		{"Map", Func, 0, "func(mapping func(rune) rune, s string) string"},
		{"NewReader", Func, 0, "func(s string) *Reader"},
		{"NewReplacer", Func, 0, "func(oldnew ...string) *Replacer"},
		{"Reader", Type, 0, ""},
		{"Repeat", Func, 0, "func(s string, count int) string"},
		{"Replace", Func, 0, "func(s string, old string, new string, n int) string"},
		{"ReplaceAll", Func, 12, "func(s string, old string, new string) string"},
		{"Replacer", Type, 0, ""},
		{"Split", Func, 0, "func(s string, sep string) []string"},
		{"SplitAfter", Func, 0, "func(s string, sep string) []string"},
		{"SplitAfterN", Func, 0, "func(s string, sep string, n int) []string"},
		{"SplitAfterSeq", Func, 24, "func(s string, sep string) iter.Seq[string]"},
		{"SplitN", Func, 0, "func(s string, sep string, n int) []string"},
		{"SplitSeq", Func, 24, "func(s string, sep string) iter.Seq[string]"},
		{"Title", Func, 0, "func(s string) string"},
		{"ToLower", Func, 0, "func(s string) string"},
		{"ToLowerSpecial", Func, 0, "func(c unicode.SpecialCase, s string) string"},
		{"ToTitle", Func, 0, "func(s string) string"},
		{"ToTitleSpecial", Func, 0, "func(c unicode.SpecialCase, s string) string"},
		{"ToUpper", Func, 0, "func(s string) string"},
		{"ToUpperSpecial", Func, 0, "func(c unicode.SpecialCase, s string) string"},
		{"ToValidUTF8", Func, 13, "func(s string, replacement string) string"},
		{"Trim", Func, 0, "func(s string, cutset string) string"},
		{"TrimFunc", Func, 0, "func(s string, f func(rune) bool) string"},
		{"TrimLeft", Func, 0, "func(s string, cutset string) string"},
		{"TrimLeftFunc", Func, 0, "func(s string, f func(rune) bool) string"},
		{"TrimPrefix", Func, 1, "func(s string, prefix string) string"},
		{"TrimRight", Func, 0, "func(s string, cutset string) string"},
		{"TrimRightFunc", Func, 0, "func(s string, f func(rune) bool) string"},
		{"TrimSpace", Func, 0, "func(s string) string"},
		{"TrimSuffix", Func, 1, "func(s string, suffix string) string"},
	},
	"structs": {
		{"HostLayout", Type, 23, ""},
	},
	"sync": {
		{"(*Cond).Broadcast", Method, 0, ""},
		{"(*Cond).Signal", Method, 0, ""},
		{"(*Cond).Wait", Method, 0, ""},
		{"(*Map).Clear", Method, 23, ""},
		{"(*Map).CompareAndDelete", Method, 20, ""},
		{"(*Map).CompareAndSwap", Method, 20, ""},
		{"(*Map).Delete", Method, 9, ""},
		{"(*Map).Load", Method, 9, ""},
		{"(*Map).LoadAndDelete", Method, 15, ""},
		{"(*Map).LoadOrStore", Method, 9, ""},
		{"(*Map).Range", Method, 9, ""},
		{"(*Map).Store", Method, 9, ""},
		{"(*Map).Swap", Method, 20, ""},
		{"(*Mutex).Lock", Method, 0, ""},
		{"(*Mutex).TryLock", Method, 18, ""},
		{"(*Mutex).Unlock", Method, 0, ""},
		{"(*Once).Do", Method, 0, ""},
		{"(*Pool).Get", Method, 3, ""},
		{"(*Pool).Put", Method, 3, ""},
		{"(*RWMutex).Lock", Method, 0, ""},
		{"(*RWMutex).RLock", Method, 0, ""},
		{"(*RWMutex).RLocker", Method, 0, ""},
		{"(*RWMutex).RUnlock", Method, 0, ""},
		{"(*RWMutex).TryLock", Method, 18, ""},
		{"(*RWMutex).TryRLock", Method, 18, ""},
		{"(*RWMutex).Unlock", Method, 0, ""},
		{"(*WaitGroup).Add", Method, 0, ""},
		{"(*WaitGroup).Done", Method, 0, ""},
		{"(*WaitGroup).Go", Method, 25, ""},
		{"(*WaitGroup).Wait", Method, 0, ""},
		{"(Locker).Lock", Method, 0, ""},
		{"(Locker).Unlock", Method, 0, ""},
		{"Cond", Type, 0, ""},
		{"Cond.L", Field, 0, ""},
		{"Locker", Type, 0, ""},
		{"Map", Type, 9, ""},
		{"Mutex", Type, 0, ""},
		{"NewCond", Func, 0, "func(l Locker) *Cond"},
		{"Once", Type, 0, ""},
		{"OnceFunc", Func, 21, "func(f func()) func()"},
		{"OnceValue", Func, 21, "func[T any](f func() T) func() T"},
		{"OnceValues", Func, 21, "func[T1, T2 any](f func() (T1, T2)) func() (T1, T2)"},
		{"Pool", Type, 3, ""},
		{"Pool.New", Field, 3, ""},
		{"RWMutex", Type, 0, ""},
		{"WaitGroup", Type, 0, ""},
	},
	"sync/atomic": {
		{"(*Bool).CompareAndSwap", Method, 19, ""},
		{"(*Bool).Load", Method, 19, ""},
		{"(*Bool).Store", Method, 19, ""},
		{"(*Bool).Swap", Method, 19, ""},
		{"(*Int32).Add", Method, 19, ""},
		{"(*Int32).And", Method, 23, ""},
		{"(*Int32).CompareAndSwap", Method, 19, ""},
		{"(*Int32).Load", Method, 19, ""},
		{"(*Int32).Or", Method, 23, ""},
		{"(*Int32).Store", Method, 19, ""},
		{"(*Int32).Swap", Method, 19, ""},
		{"(*Int64).Add", Method, 19, ""},
		{"(*Int64).And", Method, 23, ""},
		{"(*Int64).CompareAndSwap", Method, 19, ""},
		{"(*Int64).Load", Method, 19, ""},
		{"(*Int64).Or", Method, 23, ""},
		{"(*Int64).Store", Method, 19, ""},
		{"(*Int64).Swap", Method, 19, ""},
		{"(*Pointer).CompareAndSwap", Method, 19, ""},
		{"(*Pointer).Load", Method, 19, ""},
		{"(*Pointer).Store", Method, 19, ""},
		{"(*Pointer).Swap", Method, 19, ""},
		{"(*Uint32).Add", Method, 19, ""},
		{"(*Uint32).And", Method, 23, ""},
		{"(*Uint32).CompareAndSwap", Method, 19, ""},
		{"(*Uint32).Load", Method, 19, ""},
		{"(*Uint32).Or", Method, 23, ""},
		{"(*Uint32).Store", Method, 19, ""},
		{"(*Uint32).Swap", Method, 19, ""},
		{"(*Uint64).Add", Method, 19, ""},
		{"(*Uint64).And", Method, 23, ""},
		{"(*Uint64).CompareAndSwap", Method, 19, ""},
		{"(*Uint64).Load", Method, 19, ""},
		{"(*Uint64).Or", Method, 23, ""},
		{"(*Uint64).Store", Method, 19, ""},
		{"(*Uint64).Swap", Method, 19, ""},
		{"(*Uintptr).Add", Method, 19, ""},
		{"(*Uintptr).And", Method, 23, ""},
		{"(*Uintptr).CompareAndSwap", Method, 19, ""},
		{"(*Uintptr).Load", Method, 19, ""},
		{"(*Uintptr).Or", Method, 23, ""},
		{"(*Uintptr).Store", Method, 19, ""},
		{"(*Uintptr).Swap", Method, 19, ""},
		{"(*Value).CompareAndSwap", Method, 17, ""},
		{"(*Value).Load", Method, 4, ""},
		{"(*Value).Store", Method, 4, ""},
		{"(*Value).Swap", Method, 17, ""},
		{"AddInt32", Func, 0, "func(addr *int32, delta int32) (new int32)"},
		{"AddInt64", Func, 0, "func(addr *int64, delta int64) (new int64)"},
		{"AddUint32", Func, 0, "func(addr *uint32, delta uint32) (new uint32)"},
		{"AddUint64", Func, 0, "func(addr *uint64, delta uint64) (new uint64)"},
		{"AddUintptr", Func, 0, "func(addr *uintptr, delta uintptr) (new uintptr)"},
		{"AndInt32", Func, 23, "func(addr *int32, mask int32) (old int32)"},
		{"AndInt64", Func, 23, "func(addr *int64, mask int64) (old int64)"},
		{"AndUint32", Func, 23, "func(addr *uint32, mask uint32) (old uint32)"},
		{"AndUint64", Func, 23, "func(addr *uint64, mask uint64) (old uint64)"},
		{"AndUintptr", Func, 23, "func(addr *uintptr, mask uintptr) (old uintptr)"},
		{"Bool", Type, 19, ""},
		{"CompareAndSwapInt32", Func, 0, "func(addr *int32, old int32, new int32) (swapped bool)"},
		{"CompareAndSwapInt64", Func, 0, "func(addr *int64, old int64, new int64) (swapped bool)"},
		{"CompareAndSwapPointer", Func, 0, "func(addr *unsafe.Pointer, old unsafe.Pointer, new unsafe.Pointer) (swapped bool)"},
		{"CompareAndSwapUint32", Func, 0, "func(addr *uint32, old uint32, new uint32) (swapped bool)"},
		{"CompareAndSwapUint64", Func, 0, "func(addr *uint64, old uint64, new uint64) (swapped bool)"},
		{"CompareAndSwapUintptr", Func, 0, "func(addr *uintptr, old uintptr, new uintptr) (swapped bool)"},
		{"Int32", Type, 19, ""},
		{"Int64", Type, 19, ""},
		{"LoadInt32", Func, 0, "func(addr *int32) (val int32)"},
		{"LoadInt64", Func, 0, "func(addr *int64) (val int64)"},
		{"LoadPointer", Func, 0, "func(addr *unsafe.Pointer) (val unsafe.Pointer)"},
		{"LoadUint32", Func, 0, "func(addr *uint32) (val uint32)"},
		{"LoadUint64", Func, 0, "func(addr *uint64) (val uint64)"},
		{"LoadUintptr", Func, 0, "func(addr *uintptr) (val uintptr)"},
		{"OrInt32", Func, 23, "func(addr *int32, mask int32) (old int32)"},
		{"OrInt64", Func, 23, "func(addr *int64, mask int64) (old int64)"},
		{"OrUint32", Func, 23, "func(addr *uint32, mask uint32) (old uint32)"},
		{"OrUint64", Func, 23, "func(addr *uint64, mask uint64) (old uint64)"},
		{"OrUintptr", Func, 23, "func(addr *uintptr, mask uintptr) (old uintptr)"},
		{"Pointer", Type, 19, ""},
		{"StoreInt32", Func, 0, "func(addr *int32, val int32)"},
		{"StoreInt64", Func, 0, "func(addr *int64, val int64)"},
		{"StorePointer", Func, 0, "func(addr *unsafe.Pointer, val unsafe.Pointer)"},
		{"StoreUint32", Func, 0, "func(addr *uint32, val uint32)"},
		{"StoreUint64", Func, 0, "func(addr *uint64, val uint64)"},
		{"StoreUintptr", Func, 0, "func(addr *uintptr, val uintptr)"},
		{"SwapInt32", Func, 2, "func(addr *int32, new int32) (old int32)"},
		{"SwapInt64", Func, 2, "func(addr *int64, new int64) (old int64)"},
		{"SwapPointer", Func, 2, "func(addr *unsafe.Pointer, new unsafe.Pointer) (old unsafe.Pointer)"},
		{"SwapUint32", Func, 2, "func(addr *uint32, new uint32) (old uint32)"},
		{"SwapUint64", Func, 2, "func(addr *uint64, new uint64) (old uint64)"},
		{"SwapUintptr", Func, 2, "func(addr *uintptr, new uintptr) (old uintptr)"},
		{"Uint32", Type, 19, ""},
		{"Uint64", Type, 19, ""},
		{"Uintptr", Type, 19, ""},
		{"Value", Type, 4, ""},
	},
	"syscall": {
		{"(*Cmsghdr).SetLen", Method, 0, ""},
		{"(*DLL).FindProc", Method, 0, ""},
		{"(*DLL).MustFindProc", Method, 0, ""},
		{"(*DLL).Release", Method, 0, ""},
		{"(*DLLError).Error", Method, 0, ""},
		{"(*DLLError).Unwrap", Method, 16, ""},
		{"(*Filetime).Nanoseconds", Method, 0, ""},
		{"(*Iovec).SetLen", Method, 0, ""},
		{"(*LazyDLL).Handle", Method, 0, ""},
		{"(*LazyDLL).Load", Method, 0, ""},
		{"(*LazyDLL).NewProc", Method, 0, ""},
		{"(*LazyProc).Addr", Method, 0, ""},
		{"(*LazyProc).Call", Method, 0, ""},
		{"(*LazyProc).Find", Method, 0, ""},
		{"(*Msghdr).SetControllen", Method, 0, ""},
		{"(*Proc).Addr", Method, 0, ""},
		{"(*Proc).Call", Method, 0, ""},
		{"(*PtraceRegs).PC", Method, 0, ""},
		{"(*PtraceRegs).SetPC", Method, 0, ""},
		{"(*RawSockaddrAny).Sockaddr", Method, 0, ""},
		{"(*SID).Copy", Method, 0, ""},
		{"(*SID).Len", Method, 0, ""},
		{"(*SID).LookupAccount", Method, 0, ""},
		{"(*SID).String", Method, 0, ""},
		{"(*Timespec).Nano", Method, 0, ""},
		{"(*Timespec).Unix", Method, 0, ""},
		{"(*Timeval).Nano", Method, 0, ""},
		{"(*Timeval).Nanoseconds", Method, 0, ""},
		{"(*Timeval).Unix", Method, 0, ""},
		{"(Conn).SyscallConn", Method, 9, ""},
		{"(Errno).Error", Method, 0, ""},
		{"(Errno).Is", Method, 13, ""},
		{"(Errno).Temporary", Method, 0, ""},
		{"(Errno).Timeout", Method, 0, ""},
		{"(RawConn).Control", Method, 9, ""},
		{"(RawConn).Read", Method, 9, ""},
		{"(RawConn).Write", Method, 9, ""},
		{"(Signal).Signal", Method, 0, ""},
		{"(Signal).String", Method, 0, ""},
		{"(Token).Close", Method, 0, ""},
		{"(Token).GetTokenPrimaryGroup", Method, 0, ""},
		{"(Token).GetTokenUser", Method, 0, ""},
		{"(Token).GetUserProfileDirectory", Method, 0, ""},
		{"(WaitStatus).Continued", Method, 0, ""},
		{"(WaitStatus).CoreDump", Method, 0, ""},
		{"(WaitStatus).ExitStatus", Method, 0, ""},
		{"(WaitStatus).Exited", Method, 0, ""},
		{"(WaitStatus).Signal", Method, 0, ""},
		{"(WaitStatus).Signaled", Method, 0, ""},
		{"(WaitStatus).StopSignal", Method, 0, ""},
		{"(WaitStatus).Stopped", Method, 0, ""},
		{"(WaitStatus).TrapCause", Method, 0, ""},
		{"AF_ALG", Const, 0, ""},
		{"AF_APPLETALK", Const, 0, ""},
		{"AF_ARP", Const, 0, ""},
		{"AF_ASH", Const, 0, ""},
		{"AF_ATM", Const, 0, ""},
		{"AF_ATMPVC", Const, 0, ""},
		{"AF_ATMSVC", Const, 0, ""},
		{"AF_AX25", Const, 0, ""},
		{"AF_BLUETOOTH", Const, 0, ""},
		{"AF_BRIDGE", Const, 0, ""},
		{"AF_CAIF", Const, 0, ""},
		{"AF_CAN", Const, 0, ""},
		{"AF_CCITT", Const, 0, ""},
		{"AF_CHAOS", Const, 0, ""},
		{"AF_CNT", Const, 0, ""},
		{"AF_COIP", Const, 0, ""},
		{"AF_DATAKIT", Const, 0, ""},
		{"AF_DECnet", Const, 0, ""},
		{"AF_DLI", Const, 0, ""},
		{"AF_E164", Const, 0, ""},
		{"AF_ECMA", Const, 0, ""},
		{"AF_ECONET", Const, 0, ""},
		{"AF_ENCAP", Const, 1, ""},
		{"AF_FILE", Const, 0, ""},
		{"AF_HYLINK", Const, 0, ""},
		{"AF_IEEE80211", Const, 0, ""},
		{"AF_IEEE802154", Const, 0, ""},
		{"AF_IMPLINK", Const, 0, ""},
		{"AF_INET", Const, 0, ""},
		{"AF_INET6", Const, 0, ""},
		{"AF_INET6_SDP", Const, 3, ""},
		{"AF_INET_SDP", Const, 3, ""},
		{"AF_IPX", Const, 0, ""},
		{"AF_IRDA", Const, 0, ""},
		{"AF_ISDN", Const, 0, ""},
		{"AF_ISO", Const, 0, ""},
		{"AF_IUCV", Const, 0, ""},
		{"AF_KEY", Const, 0, ""},
		{"AF_LAT", Const, 0, ""},
		{"AF_LINK", Const, 0, ""},
		{"AF_LLC", Const, 0, ""},
		{"AF_LOCAL", Const, 0, ""},
		{"AF_MAX", Const, 0, ""},
		{"AF_MPLS", Const, 1, ""},
		{"AF_NATM", Const, 0, ""},
		{"AF_NDRV", Const, 0, ""},
		{"AF_NETBEUI", Const, 0, ""},
		{"AF_NETBIOS", Const, 0, ""},
		{"AF_NETGRAPH", Const, 0, ""},
		{"AF_NETLINK", Const, 0, ""},
		{"AF_NETROM", Const, 0, ""},
		{"AF_NS", Const, 0, ""},
		{"AF_OROUTE", Const, 1, ""},
		{"AF_OSI", Const, 0, ""},
		{"AF_PACKET", Const, 0, ""},
		{"AF_PHONET", Const, 0, ""},
		{"AF_PPP", Const, 0, ""},
		{"AF_PPPOX", Const, 0, ""},
		{"AF_PUP", Const, 0, ""},
		{"AF_RDS", Const, 0, ""},
		{"AF_RESERVED_36", Const, 0, ""},
		{"AF_ROSE", Const, 0, ""},
		{"AF_ROUTE", Const, 0, ""},
		{"AF_RXRPC", Const, 0, ""},
		{"AF_SCLUSTER", Const, 0, ""},
		{"AF_SECURITY", Const, 0, ""},
		{"AF_SIP", Const, 0, ""},
		{"AF_SLOW", Const, 0, ""},
		{"AF_SNA", Const, 0, ""},
		{"AF_SYSTEM", Const, 0, ""},
		{"AF_TIPC", Const, 0, ""},
		{"AF_UNIX", Const, 0, ""},
		{"AF_UNSPEC", Const, 0, ""},
		{"AF_UTUN", Const, 16, ""},
		{"AF_VENDOR00", Const, 0, ""},
		{"AF_VENDOR01", Const, 0, ""},
		{"AF_VENDOR02", Const, 0, ""},
		{"AF_VENDOR03", Const, 0, ""},
		{"AF_VENDOR04", Const, 0, ""},
		{"AF_VENDOR05", Const, 0, ""},
		{"AF_VENDOR06", Const, 0, ""},
		{"AF_VENDOR07", Const, 0, ""},
		{"AF_VENDOR08", Const, 0, ""},
		{"AF_VENDOR09", Const, 0, ""},
		{"AF_VENDOR10", Const, 0, ""},
		{"AF_VENDOR11", Const, 0, ""},
		{"AF_VENDOR12", Const, 0, ""},
		{"AF_VENDOR13", Const, 0, ""},
		{"AF_VENDOR14", Const, 0, ""},
		{"AF_VENDOR15", Const, 0, ""},
		{"AF_VENDOR16", Const, 0, ""},
		{"AF_VENDOR17", Const, 0, ""},
		{"AF_VENDOR18", Const, 0, ""},
		{"AF_VENDOR19", Const, 0, ""},
		{"AF_VENDOR20", Const, 0, ""},
		{"AF_VENDOR21", Const, 0, ""},
		{"AF_VENDOR22", Const, 0, ""},
		{"AF_VENDOR23", Const, 0, ""},
		{"AF_VENDOR24", Const, 0, ""},
		{"AF_VENDOR25", Const, 0, ""},
		{"AF_VENDOR26", Const, 0, ""},
		{"AF_VENDOR27", Const, 0, ""},
		{"AF_VENDOR28", Const, 0, ""},
		{"AF_VENDOR29", Const, 0, ""},
		{"AF_VENDOR30", Const, 0, ""},
		{"AF_VENDOR31", Const, 0, ""},
		{"AF_VENDOR32", Const, 0, ""},
		{"AF_VENDOR33", Const, 0, ""},
		{"AF_VENDOR34", Const, 0, ""},
		{"AF_VENDOR35", Const, 0, ""},
		{"AF_VENDOR36", Const, 0, ""},
		{"AF_VENDOR37", Const, 0, ""},
		{"AF_VENDOR38", Const, 0, ""},
		{"AF_VENDOR39", Const, 0, ""},
		{"AF_VENDOR40", Const, 0, ""},
		{"AF_VENDOR41", Const, 0, ""},
		{"AF_VENDOR42", Const, 0, ""},
		{"AF_VENDOR43", Const, 0, ""},
		{"AF_VENDOR44", Const, 0, ""},
		{"AF_VENDOR45", Const, 0, ""},
		{"AF_VENDOR46", Const, 0, ""},
		{"AF_VENDOR47", Const, 0, ""},
		{"AF_WANPIPE", Const, 0, ""},
		{"AF_X25", Const, 0, ""},
		{"AI_CANONNAME", Const, 1, ""},
		{"AI_NUMERICHOST", Const, 1, ""},
		{"AI_PASSIVE", Const, 1, ""},
		{"APPLICATION_ERROR", Const, 0, ""},
		{"ARPHRD_ADAPT", Const, 0, ""},
		{"ARPHRD_APPLETLK", Const, 0, ""},
		{"ARPHRD_ARCNET", Const, 0, ""},
		{"ARPHRD_ASH", Const, 0, ""},
		{"ARPHRD_ATM", Const, 0, ""},
		{"ARPHRD_AX25", Const, 0, ""},
		{"ARPHRD_BIF", Const, 0, ""},
		{"ARPHRD_CHAOS", Const, 0, ""},
		{"ARPHRD_CISCO", Const, 0, ""},
		{"ARPHRD_CSLIP", Const, 0, ""},
		{"ARPHRD_CSLIP6", Const, 0, ""},
		{"ARPHRD_DDCMP", Const, 0, ""},
		{"ARPHRD_DLCI", Const, 0, ""},
		{"ARPHRD_ECONET", Const, 0, ""},
		{"ARPHRD_EETHER", Const, 0, ""},
		{"ARPHRD_ETHER", Const, 0, ""},
		{"ARPHRD_EUI64", Const, 0, ""},
		{"ARPHRD_FCAL", Const, 0, ""},
		{"ARPHRD_FCFABRIC", Const, 0, ""},
		{"ARPHRD_FCPL", Const, 0, ""},
		{"ARPHRD_FCPP", Const, 0, ""},
		{"ARPHRD_FDDI", Const, 0, ""},
		{"ARPHRD_FRAD", Const, 0, ""},
		{"ARPHRD_FRELAY", Const, 1, ""},
		{"ARPHRD_HDLC", Const, 0, ""},
		{"ARPHRD_HIPPI", Const, 0, ""},
		{"ARPHRD_HWX25", Const, 0, ""},
		{"ARPHRD_IEEE1394", Const, 0, ""},
		{"ARPHRD_IEEE802", Const, 0, ""},
		{"ARPHRD_IEEE80211", Const, 0, ""},
		{"ARPHRD_IEEE80211_PRISM", Const, 0, ""},
		{"ARPHRD_IEEE80211_RADIOTAP", Const, 0, ""},
		{"ARPHRD_IEEE802154", Const, 0, ""},
		{"ARPHRD_IEEE802154_PHY", Const, 0, ""},
		{"ARPHRD_IEEE802_TR", Const, 0, ""},
		{"ARPHRD_INFINIBAND", Const, 0, ""},
		{"ARPHRD_IPDDP", Const, 0, ""},
		{"ARPHRD_IPGRE", Const, 0, ""},
		{"ARPHRD_IRDA", Const, 0, ""},
		{"ARPHRD_LAPB", Const, 0, ""},
		{"ARPHRD_LOCALTLK", Const, 0, ""},
		{"ARPHRD_LOOPBACK", Const, 0, ""},
		{"ARPHRD_METRICOM", Const, 0, ""},
		{"ARPHRD_NETROM", Const, 0, ""},
		{"ARPHRD_NONE", Const, 0, ""},
		{"ARPHRD_PIMREG", Const, 0, ""},
		{"ARPHRD_PPP", Const, 0, ""},
		{"ARPHRD_PRONET", Const, 0, ""},
		{"ARPHRD_RAWHDLC", Const, 0, ""},
		{"ARPHRD_ROSE", Const, 0, ""},
		{"ARPHRD_RSRVD", Const, 0, ""},
		{"ARPHRD_SIT", Const, 0, ""},
		{"ARPHRD_SKIP", Const, 0, ""},
		{"ARPHRD_SLIP", Const, 0, ""},
		{"ARPHRD_SLIP6", Const, 0, ""},
		{"ARPHRD_STRIP", Const, 1, ""},
		{"ARPHRD_TUNNEL", Const, 0, ""},
		{"ARPHRD_TUNNEL6", Const, 0, ""},
		{"ARPHRD_VOID", Const, 0, ""},
		{"ARPHRD_X25", Const, 0, ""},
		{"AUTHTYPE_CLIENT", Const, 0, ""},
		{"AUTHTYPE_SERVER", Const, 0, ""},
		{"Accept", Func, 0, "func(fd int) (nfd int, sa Sockaddr, err error)"},
		{"Accept4", Func, 1, "func(fd int, flags int) (nfd int, sa Sockaddr, err error)"},
		{"AcceptEx", Func, 0, ""},
		{"Access", Func, 0, "func(path string, mode uint32) (err error)"},
		{"Acct", Func, 0, "func(path string) (err error)"},
		{"AddrinfoW", Type, 1, ""},
		{"AddrinfoW.Addr", Field, 1, ""},
		{"AddrinfoW.Addrlen", Field, 1, ""},
		{"AddrinfoW.Canonname", Field, 1, ""},
		{"AddrinfoW.Family", Field, 1, ""},
		{"AddrinfoW.Flags", Field, 1, ""},
		{"AddrinfoW.Next", Field, 1, ""},
		{"AddrinfoW.Protocol", Field, 1, ""},
		{"AddrinfoW.Socktype", Field, 1, ""},
		{"Adjtime", Func, 0, ""},
		{"Adjtimex", Func, 0, "func(buf *Timex) (state int, err error)"},
		{"AllThreadsSyscall", Func, 16, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"AllThreadsSyscall6", Func, 16, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr, a4 uintptr, a5 uintptr, a6 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"AttachLsf", Func, 0, "func(fd int, i []SockFilter) error"},
		{"B0", Const, 0, ""},
		{"B1000000", Const, 0, ""},
		{"B110", Const, 0, ""},
		{"B115200", Const, 0, ""},
		{"B1152000", Const, 0, ""},
		{"B1200", Const, 0, ""},
		{"B134", Const, 0, ""},
		{"B14400", Const, 1, ""},
		{"B150", Const, 0, ""},
		{"B1500000", Const, 0, ""},
		{"B1800", Const, 0, ""},
		{"B19200", Const, 0, ""},
		{"B200", Const, 0, ""},
		{"B2000000", Const, 0, ""},
		{"B230400", Const, 0, ""},
		{"B2400", Const, 0, ""},
		{"B2500000", Const, 0, ""},
		{"B28800", Const, 1, ""},
		{"B300", Const, 0, ""},
		{"B3000000", Const, 0, ""},
		{"B3500000", Const, 0, ""},
		{"B38400", Const, 0, ""},
		{"B4000000", Const, 0, ""},
		{"B460800", Const, 0, ""},
		{"B4800", Const, 0, ""},
		{"B50", Const, 0, ""},
		{"B500000", Const, 0, ""},
		{"B57600", Const, 0, ""},
		{"B576000", Const, 0, ""},
		{"B600", Const, 0, ""},
		{"B7200", Const, 1, ""},
		{"B75", Const, 0, ""},
		{"B76800", Const, 1, ""},
		{"B921600", Const, 0, ""},
		{"B9600", Const, 0, ""},
		{"BASE_PROTOCOL", Const, 2, ""},
		{"BIOCFEEDBACK", Const, 0, ""},
		{"BIOCFLUSH", Const, 0, ""},
		{"BIOCGBLEN", Const, 0, ""},
		{"BIOCGDIRECTION", Const, 0, ""},
		{"BIOCGDIRFILT", Const, 1, ""},
		{"BIOCGDLT", Const, 0, ""},
		{"BIOCGDLTLIST", Const, 0, ""},
		{"BIOCGETBUFMODE", Const, 0, ""},
		{"BIOCGETIF", Const, 0, ""},
		{"BIOCGETZMAX", Const, 0, ""},
		{"BIOCGFEEDBACK", Const, 1, ""},
		{"BIOCGFILDROP", Const, 1, ""},
		{"BIOCGHDRCMPLT", Const, 0, ""},
		{"BIOCGRSIG", Const, 0, ""},
		{"BIOCGRTIMEOUT", Const, 0, ""},
		{"BIOCGSEESENT", Const, 0, ""},
		{"BIOCGSTATS", Const, 0, ""},
		{"BIOCGSTATSOLD", Const, 1, ""},
		{"BIOCGTSTAMP", Const, 1, ""},
		{"BIOCIMMEDIATE", Const, 0, ""},
		{"BIOCLOCK", Const, 0, ""},
		{"BIOCPROMISC", Const, 0, ""},
		{"BIOCROTZBUF", Const, 0, ""},
		{"BIOCSBLEN", Const, 0, ""},
		{"BIOCSDIRECTION", Const, 0, ""},
		{"BIOCSDIRFILT", Const, 1, ""},
		{"BIOCSDLT", Const, 0, ""},
		{"BIOCSETBUFMODE", Const, 0, ""},
		{"BIOCSETF", Const, 0, ""},
		{"BIOCSETFNR", Const, 0, ""},
		{"BIOCSETIF", Const, 0, ""},
		{"BIOCSETWF", Const, 0, ""},
		{"BIOCSETZBUF", Const, 0, ""},
		{"BIOCSFEEDBACK", Const, 1, ""},
		{"BIOCSFILDROP", Const, 1, ""},
		{"BIOCSHDRCMPLT", Const, 0, ""},
		{"BIOCSRSIG", Const, 0, ""},
		{"BIOCSRTIMEOUT", Const, 0, ""},
		{"BIOCSSEESENT", Const, 0, ""},
		{"BIOCSTCPF", Const, 1, ""},
		{"BIOCSTSTAMP", Const, 1, ""},
		{"BIOCSUDPF", Const, 1, ""},
		{"BIOCVERSION", Const, 0, ""},
		{"BPF_A", Const, 0, ""},
		{"BPF_ABS", Const, 0, ""},
		{"BPF_ADD", Const, 0, ""},
		{"BPF_ALIGNMENT", Const, 0, ""},
		{"BPF_ALIGNMENT32", Const, 1, ""},
		{"BPF_ALU", Const, 0, ""},
		{"BPF_AND", Const, 0, ""},
		{"BPF_B", Const, 0, ""},
		{"BPF_BUFMODE_BUFFER", Const, 0, ""},
		{"BPF_BUFMODE_ZBUF", Const, 0, ""},
		{"BPF_DFLTBUFSIZE", Const, 1, ""},
		{"BPF_DIRECTION_IN", Const, 1, ""},
		{"BPF_DIRECTION_OUT", Const, 1, ""},
		{"BPF_DIV", Const, 0, ""},
		{"BPF_H", Const, 0, ""},
		{"BPF_IMM", Const, 0, ""},
		{"BPF_IND", Const, 0, ""},
		{"BPF_JA", Const, 0, ""},
		{"BPF_JEQ", Const, 0, ""},
		{"BPF_JGE", Const, 0, ""},
		{"BPF_JGT", Const, 0, ""},
		{"BPF_JMP", Const, 0, ""},
		{"BPF_JSET", Const, 0, ""},
		{"BPF_K", Const, 0, ""},
		{"BPF_LD", Const, 0, ""},
		{"BPF_LDX", Const, 0, ""},
		{"BPF_LEN", Const, 0, ""},
		{"BPF_LSH", Const, 0, ""},
		{"BPF_MAJOR_VERSION", Const, 0, ""},
		{"BPF_MAXBUFSIZE", Const, 0, ""},
		{"BPF_MAXINSNS", Const, 0, ""},
		{"BPF_MEM", Const, 0, ""},
		{"BPF_MEMWORDS", Const, 0, ""},
		{"BPF_MINBUFSIZE", Const, 0, ""},
		{"BPF_MINOR_VERSION", Const, 0, ""},
		{"BPF_MISC", Const, 0, ""},
		{"BPF_MSH", Const, 0, ""},
		{"BPF_MUL", Const, 0, ""},
		{"BPF_NEG", Const, 0, ""},
		{"BPF_OR", Const, 0, ""},
		{"BPF_RELEASE", Const, 0, ""},
		{"BPF_RET", Const, 0, ""},
		{"BPF_RSH", Const, 0, ""},
		{"BPF_ST", Const, 0, ""},
		{"BPF_STX", Const, 0, ""},
		{"BPF_SUB", Const, 0, ""},
		{"BPF_TAX", Const, 0, ""},
		{"BPF_TXA", Const, 0, ""},
		{"BPF_T_BINTIME", Const, 1, ""},
		{"BPF_T_BINTIME_FAST", Const, 1, ""},
		{"BPF_T_BINTIME_MONOTONIC", Const, 1, ""},
		{"BPF_T_BINTIME_MONOTONIC_FAST", Const, 1, ""},
		{"BPF_T_FAST", Const, 1, ""},
		{"BPF_T_FLAG_MASK", Const, 1, ""},
		{"BPF_T_FORMAT_MASK", Const, 1, ""},
		{"BPF_T_MICROTIME", Const, 1, ""},
		{"BPF_T_MICROTIME_FAST", Const, 1, ""},
		{"BPF_T_MICROTIME_MONOTONIC", Const, 1, ""},
		{"BPF_T_MICROTIME_MONOTONIC_FAST", Const, 1, ""},
		{"BPF_T_MONOTONIC", Const, 1, ""},
		{"BPF_T_MONOTONIC_FAST", Const, 1, ""},
		{"BPF_T_NANOTIME", Const, 1, ""},
		{"BPF_T_NANOTIME_FAST", Const, 1, ""},
		{"BPF_T_NANOTIME_MONOTONIC", Const, 1, ""},
		{"BPF_T_NANOTIME_MONOTONIC_FAST", Const, 1, ""},
		{"BPF_T_NONE", Const, 1, ""},
		{"BPF_T_NORMAL", Const, 1, ""},
		{"BPF_W", Const, 0, ""},
		{"BPF_X", Const, 0, ""},
		{"BRKINT", Const, 0, ""},
		{"Bind", Func, 0, "func(fd int, sa Sockaddr) (err error)"},
		{"BindToDevice", Func, 0, "func(fd int, device string) (err error)"},
		{"BpfBuflen", Func, 0, ""},
		{"BpfDatalink", Func, 0, ""},
		{"BpfHdr", Type, 0, ""},
		{"BpfHdr.Caplen", Field, 0, ""},
		{"BpfHdr.Datalen", Field, 0, ""},
		{"BpfHdr.Hdrlen", Field, 0, ""},
		{"BpfHdr.Pad_cgo_0", Field, 0, ""},
		{"BpfHdr.Tstamp", Field, 0, ""},
		{"BpfHeadercmpl", Func, 0, ""},
		{"BpfInsn", Type, 0, ""},
		{"BpfInsn.Code", Field, 0, ""},
		{"BpfInsn.Jf", Field, 0, ""},
		{"BpfInsn.Jt", Field, 0, ""},
		{"BpfInsn.K", Field, 0, ""},
		{"BpfInterface", Func, 0, ""},
		{"BpfJump", Func, 0, ""},
		{"BpfProgram", Type, 0, ""},
		{"BpfProgram.Insns", Field, 0, ""},
		{"BpfProgram.Len", Field, 0, ""},
		{"BpfProgram.Pad_cgo_0", Field, 0, ""},
		{"BpfStat", Type, 0, ""},
		{"BpfStat.Capt", Field, 2, ""},
		{"BpfStat.Drop", Field, 0, ""},
		{"BpfStat.Padding", Field, 2, ""},
		{"BpfStat.Recv", Field, 0, ""},
		{"BpfStats", Func, 0, ""},
		{"BpfStmt", Func, 0, ""},
		{"BpfTimeout", Func, 0, ""},
		{"BpfTimeval", Type, 2, ""},
		{"BpfTimeval.Sec", Field, 2, ""},
		{"BpfTimeval.Usec", Field, 2, ""},
		{"BpfVersion", Type, 0, ""},
		{"BpfVersion.Major", Field, 0, ""},
		{"BpfVersion.Minor", Field, 0, ""},
		{"BpfZbuf", Type, 0, ""},
		{"BpfZbuf.Bufa", Field, 0, ""},
		{"BpfZbuf.Bufb", Field, 0, ""},
		{"BpfZbuf.Buflen", Field, 0, ""},
		{"BpfZbufHeader", Type, 0, ""},
		{"BpfZbufHeader.Kernel_gen", Field, 0, ""},
		{"BpfZbufHeader.Kernel_len", Field, 0, ""},
		{"BpfZbufHeader.User_gen", Field, 0, ""},
		{"BpfZbufHeader.X_bzh_pad", Field, 0, ""},
		{"ByHandleFileInformation", Type, 0, ""},
		{"ByHandleFileInformation.CreationTime", Field, 0, ""},
		{"ByHandleFileInformation.FileAttributes", Field, 0, ""},
		{"ByHandleFileInformation.FileIndexHigh", Field, 0, ""},
		{"ByHandleFileInformation.FileIndexLow", Field, 0, ""},
		{"ByHandleFileInformation.FileSizeHigh", Field, 0, ""},
		{"ByHandleFileInformation.FileSizeLow", Field, 0, ""},
		{"ByHandleFileInformation.LastAccessTime", Field, 0, ""},
		{"ByHandleFileInformation.LastWriteTime", Field, 0, ""},
		{"ByHandleFileInformation.NumberOfLinks", Field, 0, ""},
		{"ByHandleFileInformation.VolumeSerialNumber", Field, 0, ""},
		{"BytePtrFromString", Func, 1, "func(s string) (*byte, error)"},
		{"ByteSliceFromString", Func, 1, "func(s string) ([]byte, error)"},
		{"CCR0_FLUSH", Const, 1, ""},
		{"CERT_CHAIN_POLICY_AUTHENTICODE", Const, 0, ""},
		{"CERT_CHAIN_POLICY_AUTHENTICODE_TS", Const, 0, ""},
		{"CERT_CHAIN_POLICY_BASE", Const, 0, ""},
		{"CERT_CHAIN_POLICY_BASIC_CONSTRAINTS", Const, 0, ""},
		{"CERT_CHAIN_POLICY_EV", Const, 0, ""},
		{"CERT_CHAIN_POLICY_MICROSOFT_ROOT", Const, 0, ""},
		{"CERT_CHAIN_POLICY_NT_AUTH", Const, 0, ""},
		{"CERT_CHAIN_POLICY_SSL", Const, 0, ""},
		{"CERT_E_CN_NO_MATCH", Const, 0, ""},
		{"CERT_E_EXPIRED", Const, 0, ""},
		{"CERT_E_PURPOSE", Const, 0, ""},
		{"CERT_E_ROLE", Const, 0, ""},
		{"CERT_E_UNTRUSTEDROOT", Const, 0, ""},
		{"CERT_STORE_ADD_ALWAYS", Const, 0, ""},
		{"CERT_STORE_DEFER_CLOSE_UNTIL_LAST_FREE_FLAG", Const, 0, ""},
		{"CERT_STORE_PROV_MEMORY", Const, 0, ""},
		{"CERT_TRUST_HAS_EXCLUDED_NAME_CONSTRAINT", Const, 0, ""},
		{"CERT_TRUST_HAS_NOT_DEFINED_NAME_CONSTRAINT", Const, 0, ""},
		{"CERT_TRUST_HAS_NOT_PERMITTED_NAME_CONSTRAINT", Const, 0, ""},
		{"CERT_TRUST_HAS_NOT_SUPPORTED_CRITICAL_EXT", Const, 0, ""},
		{"CERT_TRUST_HAS_NOT_SUPPORTED_NAME_CONSTRAINT", Const, 0, ""},
		{"CERT_TRUST_INVALID_BASIC_CONSTRAINTS", Const, 0, ""},
		{"CERT_TRUST_INVALID_EXTENSION", Const, 0, ""},
		{"CERT_TRUST_INVALID_NAME_CONSTRAINTS", Const, 0, ""},
		{"CERT_TRUST_INVALID_POLICY_CONSTRAINTS", Const, 0, ""},
		{"CERT_TRUST_IS_CYCLIC", Const, 0, ""},
		{"CERT_TRUST_IS_EXPLICIT_DISTRUST", Const, 0, ""},
		{"CERT_TRUST_IS_NOT_SIGNATURE_VALID", Const, 0, ""},
		{"CERT_TRUST_IS_NOT_TIME_VALID", Const, 0, ""},
		{"CERT_TRUST_IS_NOT_VALID_FOR_USAGE", Const, 0, ""},
		{"CERT_TRUST_IS_OFFLINE_REVOCATION", Const, 0, ""},
		{"CERT_TRUST_IS_REVOKED", Const, 0, ""},
		{"CERT_TRUST_IS_UNTRUSTED_ROOT", Const, 0, ""},
		{"CERT_TRUST_NO_ERROR", Const, 0, ""},
		{"CERT_TRUST_NO_ISSUANCE_CHAIN_POLICY", Const, 0, ""},
		{"CERT_TRUST_REVOCATION_STATUS_UNKNOWN", Const, 0, ""},
		{"CFLUSH", Const, 1, ""},
		{"CLOCAL", Const, 0, ""},
		{"CLONE_CHILD_CLEARTID", Const, 2, ""},
		{"CLONE_CHILD_SETTID", Const, 2, ""},
		{"CLONE_CLEAR_SIGHAND", Const, 20, ""},
		{"CLONE_CSIGNAL", Const, 3, ""},
		{"CLONE_DETACHED", Const, 2, ""},
		{"CLONE_FILES", Const, 2, ""},
		{"CLONE_FS", Const, 2, ""},
		{"CLONE_INTO_CGROUP", Const, 20, ""},
		{"CLONE_IO", Const, 2, ""},
		{"CLONE_NEWCGROUP", Const, 20, ""},
		{"CLONE_NEWIPC", Const, 2, ""},
		{"CLONE_NEWNET", Const, 2, ""},
		{"CLONE_NEWNS", Const, 2, ""},
		{"CLONE_NEWPID", Const, 2, ""},
		{"CLONE_NEWTIME", Const, 20, ""},
		{"CLONE_NEWUSER", Const, 2, ""},
		{"CLONE_NEWUTS", Const, 2, ""},
		{"CLONE_PARENT", Const, 2, ""},
		{"CLONE_PARENT_SETTID", Const, 2, ""},
		{"CLONE_PID", Const, 3, ""},
		{"CLONE_PIDFD", Const, 20, ""},
		{"CLONE_PTRACE", Const, 2, ""},
		{"CLONE_SETTLS", Const, 2, ""},
		{"CLONE_SIGHAND", Const, 2, ""},
		{"CLONE_SYSVSEM", Const, 2, ""},
		{"CLONE_THREAD", Const, 2, ""},
		{"CLONE_UNTRACED", Const, 2, ""},
		{"CLONE_VFORK", Const, 2, ""},
		{"CLONE_VM", Const, 2, ""},
		{"CPUID_CFLUSH", Const, 1, ""},
		{"CREAD", Const, 0, ""},
		{"CREATE_ALWAYS", Const, 0, ""},
		{"CREATE_NEW", Const, 0, ""},
		{"CREATE_NEW_PROCESS_GROUP", Const, 1, ""},
		{"CREATE_UNICODE_ENVIRONMENT", Const, 0, ""},
		{"CRYPT_DEFAULT_CONTAINER_OPTIONAL", Const, 0, ""},
		{"CRYPT_DELETEKEYSET", Const, 0, ""},
		{"CRYPT_MACHINE_KEYSET", Const, 0, ""},
		{"CRYPT_NEWKEYSET", Const, 0, ""},
		{"CRYPT_SILENT", Const, 0, ""},
		{"CRYPT_VERIFYCONTEXT", Const, 0, ""},
		{"CS5", Const, 0, ""},
		{"CS6", Const, 0, ""},
		{"CS7", Const, 0, ""},
		{"CS8", Const, 0, ""},
		{"CSIZE", Const, 0, ""},
		{"CSTART", Const, 1, ""},
		{"CSTATUS", Const, 1, ""},
		{"CSTOP", Const, 1, ""},
		{"CSTOPB", Const, 0, ""},
		{"CSUSP", Const, 1, ""},
		{"CTL_MAXNAME", Const, 0, ""},
		{"CTL_NET", Const, 0, ""},
		{"CTL_QUERY", Const, 1, ""},
		{"CTRL_BREAK_EVENT", Const, 1, ""},
		{"CTRL_CLOSE_EVENT", Const, 14, ""},
		{"CTRL_C_EVENT", Const, 1, ""},
		{"CTRL_LOGOFF_EVENT", Const, 14, ""},
		{"CTRL_SHUTDOWN_EVENT", Const, 14, ""},
		{"CancelIo", Func, 0, ""},
		{"CancelIoEx", Func, 1, ""},
		{"CertAddCertificateContextToStore", Func, 0, ""},
		{"CertChainContext", Type, 0, ""},
		{"CertChainContext.ChainCount", Field, 0, ""},
		{"CertChainContext.Chains", Field, 0, ""},
		{"CertChainContext.HasRevocationFreshnessTime", Field, 0, ""},
		{"CertChainContext.LowerQualityChainCount", Field, 0, ""},
		{"CertChainContext.LowerQualityChains", Field, 0, ""},
		{"CertChainContext.RevocationFreshnessTime", Field, 0, ""},
		{"CertChainContext.Size", Field, 0, ""},
		{"CertChainContext.TrustStatus", Field, 0, ""},
		{"CertChainElement", Type, 0, ""},
		{"CertChainElement.ApplicationUsage", Field, 0, ""},
		{"CertChainElement.CertContext", Field, 0, ""},
		{"CertChainElement.ExtendedErrorInfo", Field, 0, ""},
		{"CertChainElement.IssuanceUsage", Field, 0, ""},
		{"CertChainElement.RevocationInfo", Field, 0, ""},
		{"CertChainElement.Size", Field, 0, ""},
		{"CertChainElement.TrustStatus", Field, 0, ""},
		{"CertChainPara", Type, 0, ""},
		{"CertChainPara.CacheResync", Field, 0, ""},
		{"CertChainPara.CheckRevocationFreshnessTime", Field, 0, ""},
		{"CertChainPara.RequestedUsage", Field, 0, ""},
		{"CertChainPara.RequstedIssuancePolicy", Field, 0, ""},
		{"CertChainPara.RevocationFreshnessTime", Field, 0, ""},
		{"CertChainPara.Size", Field, 0, ""},
		{"CertChainPara.URLRetrievalTimeout", Field, 0, ""},
		{"CertChainPolicyPara", Type, 0, ""},
		{"CertChainPolicyPara.ExtraPolicyPara", Field, 0, ""},
		{"CertChainPolicyPara.Flags", Field, 0, ""},
		{"CertChainPolicyPara.Size", Field, 0, ""},
		{"CertChainPolicyStatus", Type, 0, ""},
		{"CertChainPolicyStatus.ChainIndex", Field, 0, ""},
		{"CertChainPolicyStatus.ElementIndex", Field, 0, ""},
		{"CertChainPolicyStatus.Error", Field, 0, ""},
		{"CertChainPolicyStatus.ExtraPolicyStatus", Field, 0, ""},
		{"CertChainPolicyStatus.Size", Field, 0, ""},
		{"CertCloseStore", Func, 0, ""},
		{"CertContext", Type, 0, ""},
		{"CertContext.CertInfo", Field, 0, ""},
		{"CertContext.EncodedCert", Field, 0, ""},
		{"CertContext.EncodingType", Field, 0, ""},
		{"CertContext.Length", Field, 0, ""},
		{"CertContext.Store", Field, 0, ""},
		{"CertCreateCertificateContext", Func, 0, ""},
		{"CertEnhKeyUsage", Type, 0, ""},
		{"CertEnhKeyUsage.Length", Field, 0, ""},
		{"CertEnhKeyUsage.UsageIdentifiers", Field, 0, ""},
		{"CertEnumCertificatesInStore", Func, 0, ""},
		{"CertFreeCertificateChain", Func, 0, ""},
		{"CertFreeCertificateContext", Func, 0, ""},
		{"CertGetCertificateChain", Func, 0, ""},
		{"CertInfo", Type, 11, ""},
		{"CertOpenStore", Func, 0, ""},
		{"CertOpenSystemStore", Func, 0, ""},
		{"CertRevocationCrlInfo", Type, 11, ""},
		{"CertRevocationInfo", Type, 0, ""},
		{"CertRevocationInfo.CrlInfo", Field, 0, ""},
		{"CertRevocationInfo.FreshnessTime", Field, 0, ""},
		{"CertRevocationInfo.HasFreshnessTime", Field, 0, ""},
		{"CertRevocationInfo.OidSpecificInfo", Field, 0, ""},
		{"CertRevocationInfo.RevocationOid", Field, 0, ""},
		{"CertRevocationInfo.RevocationResult", Field, 0, ""},
		{"CertRevocationInfo.Size", Field, 0, ""},
		{"CertSimpleChain", Type, 0, ""},
		{"CertSimpleChain.Elements", Field, 0, ""},
		{"CertSimpleChain.HasRevocationFreshnessTime", Field, 0, ""},
		{"CertSimpleChain.NumElements", Field, 0, ""},
		{"CertSimpleChain.RevocationFreshnessTime", Field, 0, ""},
		{"CertSimpleChain.Size", Field, 0, ""},
		{"CertSimpleChain.TrustListInfo", Field, 0, ""},
		{"CertSimpleChain.TrustStatus", Field, 0, ""},
		{"CertTrustListInfo", Type, 11, ""},
		{"CertTrustStatus", Type, 0, ""},
		{"CertTrustStatus.ErrorStatus", Field, 0, ""},
		{"CertTrustStatus.InfoStatus", Field, 0, ""},
		{"CertUsageMatch", Type, 0, ""},
		{"CertUsageMatch.Type", Field, 0, ""},
		{"CertUsageMatch.Usage", Field, 0, ""},
		{"CertVerifyCertificateChainPolicy", Func, 0, ""},
		{"Chdir", Func, 0, "func(path string) (err error)"},
		{"CheckBpfVersion", Func, 0, ""},
		{"Chflags", Func, 0, ""},
		{"Chmod", Func, 0, "func(path string, mode uint32) (err error)"},
		{"Chown", Func, 0, "func(path string, uid int, gid int) (err error)"},
		{"Chroot", Func, 0, "func(path string) (err error)"},
		{"Clearenv", Func, 0, "func()"},
		{"Close", Func, 0, "func(fd int) (err error)"},
		{"CloseHandle", Func, 0, ""},
		{"CloseOnExec", Func, 0, "func(fd int)"},
		{"Closesocket", Func, 0, ""},
		{"CmsgLen", Func, 0, "func(datalen int) int"},
		{"CmsgSpace", Func, 0, "func(datalen int) int"},
		{"Cmsghdr", Type, 0, ""},
		{"Cmsghdr.Len", Field, 0, ""},
		{"Cmsghdr.Level", Field, 0, ""},
		{"Cmsghdr.Type", Field, 0, ""},
		{"Cmsghdr.X__cmsg_data", Field, 0, ""},
		{"CommandLineToArgv", Func, 0, ""},
		{"ComputerName", Func, 0, ""},
		{"Conn", Type, 9, ""},
		{"Connect", Func, 0, "func(fd int, sa Sockaddr) (err error)"},
		{"ConnectEx", Func, 1, ""},
		{"ConvertSidToStringSid", Func, 0, ""},
		{"ConvertStringSidToSid", Func, 0, ""},
		{"CopySid", Func, 0, ""},
		{"Creat", Func, 0, "func(path string, mode uint32) (fd int, err error)"},
		{"CreateDirectory", Func, 0, ""},
		{"CreateFile", Func, 0, ""},
		{"CreateFileMapping", Func, 0, ""},
		{"CreateHardLink", Func, 4, ""},
		{"CreateIoCompletionPort", Func, 0, ""},
		{"CreatePipe", Func, 0, ""},
		{"CreateProcess", Func, 0, ""},
		{"CreateProcessAsUser", Func, 10, ""},
		{"CreateSymbolicLink", Func, 4, ""},
		{"CreateToolhelp32Snapshot", Func, 4, ""},
		{"Credential", Type, 0, ""},
		{"Credential.Gid", Field, 0, ""},
		{"Credential.Groups", Field, 0, ""},
		{"Credential.NoSetGroups", Field, 9, ""},
		{"Credential.Uid", Field, 0, ""},
		{"CryptAcquireContext", Func, 0, ""},
		{"CryptGenRandom", Func, 0, ""},
		{"CryptReleaseContext", Func, 0, ""},
		{"DIOCBSFLUSH", Const, 1, ""},
		{"DIOCOSFPFLUSH", Const, 1, ""},
		{"DLL", Type, 0, ""},
		{"DLL.Handle", Field, 0, ""},
		{"DLL.Name", Field, 0, ""},
		{"DLLError", Type, 0, ""},
		{"DLLError.Err", Field, 0, ""},
		{"DLLError.Msg", Field, 0, ""},
		{"DLLError.ObjName", Field, 0, ""},
		{"DLT_A429", Const, 0, ""},
		{"DLT_A653_ICM", Const, 0, ""},
		{"DLT_AIRONET_HEADER", Const, 0, ""},
		{"DLT_AOS", Const, 1, ""},
		{"DLT_APPLE_IP_OVER_IEEE1394", Const, 0, ""},
		{"DLT_ARCNET", Const, 0, ""},
		{"DLT_ARCNET_LINUX", Const, 0, ""},
		{"DLT_ATM_CLIP", Const, 0, ""},
		{"DLT_ATM_RFC1483", Const, 0, ""},
		{"DLT_AURORA", Const, 0, ""},
		{"DLT_AX25", Const, 0, ""},
		{"DLT_AX25_KISS", Const, 0, ""},
		{"DLT_BACNET_MS_TP", Const, 0, ""},
		{"DLT_BLUETOOTH_HCI_H4", Const, 0, ""},
		{"DLT_BLUETOOTH_HCI_H4_WITH_PHDR", Const, 0, ""},
		{"DLT_CAN20B", Const, 0, ""},
		{"DLT_CAN_SOCKETCAN", Const, 1, ""},
		{"DLT_CHAOS", Const, 0, ""},
		{"DLT_CHDLC", Const, 0, ""},
		{"DLT_CISCO_IOS", Const, 0, ""},
		{"DLT_C_HDLC", Const, 0, ""},
		{"DLT_C_HDLC_WITH_DIR", Const, 0, ""},
		{"DLT_DBUS", Const, 1, ""},
		{"DLT_DECT", Const, 1, ""},
		{"DLT_DOCSIS", Const, 0, ""},
		{"DLT_DVB_CI", Const, 1, ""},
		{"DLT_ECONET", Const, 0, ""},
		{"DLT_EN10MB", Const, 0, ""},
		{"DLT_EN3MB", Const, 0, ""},
		{"DLT_ENC", Const, 0, ""},
		{"DLT_ERF", Const, 0, ""},
		{"DLT_ERF_ETH", Const, 0, ""},
		{"DLT_ERF_POS", Const, 0, ""},
		{"DLT_FC_2", Const, 1, ""},
		{"DLT_FC_2_WITH_FRAME_DELIMS", Const, 1, ""},
		{"DLT_FDDI", Const, 0, ""},
		{"DLT_FLEXRAY", Const, 0, ""},
		{"DLT_FRELAY", Const, 0, ""},
		{"DLT_FRELAY_WITH_DIR", Const, 0, ""},
		{"DLT_GCOM_SERIAL", Const, 0, ""},
		{"DLT_GCOM_T1E1", Const, 0, ""},
		{"DLT_GPF_F", Const, 0, ""},
		{"DLT_GPF_T", Const, 0, ""},
		{"DLT_GPRS_LLC", Const, 0, ""},
		{"DLT_GSMTAP_ABIS", Const, 1, ""},
		{"DLT_GSMTAP_UM", Const, 1, ""},
		{"DLT_HDLC", Const, 1, ""},
		{"DLT_HHDLC", Const, 0, ""},
		{"DLT_HIPPI", Const, 1, ""},
		{"DLT_IBM_SN", Const, 0, ""},
		{"DLT_IBM_SP", Const, 0, ""},
		{"DLT_IEEE802", Const, 0, ""},
		{"DLT_IEEE802_11", Const, 0, ""},
		{"DLT_IEEE802_11_RADIO", Const, 0, ""},
		{"DLT_IEEE802_11_RADIO_AVS", Const, 0, ""},
		{"DLT_IEEE802_15_4", Const, 0, ""},
		{"DLT_IEEE802_15_4_LINUX", Const, 0, ""},
		{"DLT_IEEE802_15_4_NOFCS", Const, 1, ""},
		{"DLT_IEEE802_15_4_NONASK_PHY", Const, 0, ""},
		{"DLT_IEEE802_16_MAC_CPS", Const, 0, ""},
		{"DLT_IEEE802_16_MAC_CPS_RADIO", Const, 0, ""},
		{"DLT_IPFILTER", Const, 0, ""},
		{"DLT_IPMB", Const, 0, ""},
		{"DLT_IPMB_LINUX", Const, 0, ""},
		{"DLT_IPNET", Const, 1, ""},
		{"DLT_IPOIB", Const, 1, ""},
		{"DLT_IPV4", Const, 1, ""},
		{"DLT_IPV6", Const, 1, ""},
		{"DLT_IP_OVER_FC", Const, 0, ""},
		{"DLT_JUNIPER_ATM1", Const, 0, ""},
		{"DLT_JUNIPER_ATM2", Const, 0, ""},
		{"DLT_JUNIPER_ATM_CEMIC", Const, 1, ""},
		{"DLT_JUNIPER_CHDLC", Const, 0, ""},
		{"DLT_JUNIPER_ES", Const, 0, ""},
		{"DLT_JUNIPER_ETHER", Const, 0, ""},
		{"DLT_JUNIPER_FIBRECHANNEL", Const, 1, ""},
		{"DLT_JUNIPER_FRELAY", Const, 0, ""},
		{"DLT_JUNIPER_GGSN", Const, 0, ""},
		{"DLT_JUNIPER_ISM", Const, 0, ""},
		{"DLT_JUNIPER_MFR", Const, 0, ""},
		{"DLT_JUNIPER_MLFR", Const, 0, ""},
		{"DLT_JUNIPER_MLPPP", Const, 0, ""},
		{"DLT_JUNIPER_MONITOR", Const, 0, ""},
		{"DLT_JUNIPER_PIC_PEER", Const, 0, ""},
		{"DLT_JUNIPER_PPP", Const, 0, ""},
		{"DLT_JUNIPER_PPPOE", Const, 0, ""},
		{"DLT_JUNIPER_PPPOE_ATM", Const, 0, ""},
		{"DLT_JUNIPER_SERVICES", Const, 0, ""},
		{"DLT_JUNIPER_SRX_E2E", Const, 1, ""},
		{"DLT_JUNIPER_ST", Const, 0, ""},
		{"DLT_JUNIPER_VP", Const, 0, ""},
		{"DLT_JUNIPER_VS", Const, 1, ""},
		{"DLT_LAPB_WITH_DIR", Const, 0, ""},
		{"DLT_LAPD", Const, 0, ""},
		{"DLT_LIN", Const, 0, ""},
		{"DLT_LINUX_EVDEV", Const, 1, ""},
		{"DLT_LINUX_IRDA", Const, 0, ""},
		{"DLT_LINUX_LAPD", Const, 0, ""},
		{"DLT_LINUX_PPP_WITHDIRECTION", Const, 0, ""},
		{"DLT_LINUX_SLL", Const, 0, ""},
		{"DLT_LOOP", Const, 0, ""},
		{"DLT_LTALK", Const, 0, ""},
		{"DLT_MATCHING_MAX", Const, 1, ""},
		{"DLT_MATCHING_MIN", Const, 1, ""},
		{"DLT_MFR", Const, 0, ""},
		{"DLT_MOST", Const, 0, ""},
		{"DLT_MPEG_2_TS", Const, 1, ""},
		{"DLT_MPLS", Const, 1, ""},
		{"DLT_MTP2", Const, 0, ""},
		{"DLT_MTP2_WITH_PHDR", Const, 0, ""},
		{"DLT_MTP3", Const, 0, ""},
		{"DLT_MUX27010", Const, 1, ""},
		{"DLT_NETANALYZER", Const, 1, ""},
		{"DLT_NETANALYZER_TRANSPARENT", Const, 1, ""},
		{"DLT_NFC_LLCP", Const, 1, ""},
		{"DLT_NFLOG", Const, 1, ""},
		{"DLT_NG40", Const, 1, ""},
		{"DLT_NULL", Const, 0, ""},
		{"DLT_PCI_EXP", Const, 0, ""},
		{"DLT_PFLOG", Const, 0, ""},
		{"DLT_PFSYNC", Const, 0, ""},
		{"DLT_PPI", Const, 0, ""},
		{"DLT_PPP", Const, 0, ""},
		{"DLT_PPP_BSDOS", Const, 0, ""},
		{"DLT_PPP_ETHER", Const, 0, ""},
		{"DLT_PPP_PPPD", Const, 0, ""},
		{"DLT_PPP_SERIAL", Const, 0, ""},
		{"DLT_PPP_WITH_DIR", Const, 0, ""},
		{"DLT_PPP_WITH_DIRECTION", Const, 0, ""},
		{"DLT_PRISM_HEADER", Const, 0, ""},
		{"DLT_PRONET", Const, 0, ""},
		{"DLT_RAIF1", Const, 0, ""},
		{"DLT_RAW", Const, 0, ""},
		{"DLT_RAWAF_MASK", Const, 1, ""},
		{"DLT_RIO", Const, 0, ""},
		{"DLT_SCCP", Const, 0, ""},
		{"DLT_SITA", Const, 0, ""},
		{"DLT_SLIP", Const, 0, ""},
		{"DLT_SLIP_BSDOS", Const, 0, ""},
		{"DLT_STANAG_5066_D_PDU", Const, 1, ""},
		{"DLT_SUNATM", Const, 0, ""},
		{"DLT_SYMANTEC_FIREWALL", Const, 0, ""},
		{"DLT_TZSP", Const, 0, ""},
		{"DLT_USB", Const, 0, ""},
		{"DLT_USB_LINUX", Const, 0, ""},
		{"DLT_USB_LINUX_MMAPPED", Const, 1, ""},
		{"DLT_USER0", Const, 0, ""},
		{"DLT_USER1", Const, 0, ""},
		{"DLT_USER10", Const, 0, ""},
		{"DLT_USER11", Const, 0, ""},
		{"DLT_USER12", Const, 0, ""},
		{"DLT_USER13", Const, 0, ""},
		{"DLT_USER14", Const, 0, ""},
		{"DLT_USER15", Const, 0, ""},
		{"DLT_USER2", Const, 0, ""},
		{"DLT_USER3", Const, 0, ""},
		{"DLT_USER4", Const, 0, ""},
		{"DLT_USER5", Const, 0, ""},
		{"DLT_USER6", Const, 0, ""},
		{"DLT_USER7", Const, 0, ""},
		{"DLT_USER8", Const, 0, ""},
		{"DLT_USER9", Const, 0, ""},
		{"DLT_WIHART", Const, 1, ""},
		{"DLT_X2E_SERIAL", Const, 0, ""},
		{"DLT_X2E_XORAYA", Const, 0, ""},
		{"DNSMXData", Type, 0, ""},
		{"DNSMXData.NameExchange", Field, 0, ""},
		{"DNSMXData.Pad", Field, 0, ""},
		{"DNSMXData.Preference", Field, 0, ""},
		{"DNSPTRData", Type, 0, ""},
		{"DNSPTRData.Host", Field, 0, ""},
		{"DNSRecord", Type, 0, ""},
		{"DNSRecord.Data", Field, 0, ""},
		{"DNSRecord.Dw", Field, 0, ""},
		{"DNSRecord.Length", Field, 0, ""},
		{"DNSRecord.Name", Field, 0, ""},
		{"DNSRecord.Next", Field, 0, ""},
		{"DNSRecord.Reserved", Field, 0, ""},
		{"DNSRecord.Ttl", Field, 0, ""},
		{"DNSRecord.Type", Field, 0, ""},
		{"DNSSRVData", Type, 0, ""},
		{"DNSSRVData.Pad", Field, 0, ""},
		{"DNSSRVData.Port", Field, 0, ""},
		{"DNSSRVData.Priority", Field, 0, ""},
		{"DNSSRVData.Target", Field, 0, ""},
		{"DNSSRVData.Weight", Field, 0, ""},
		{"DNSTXTData", Type, 0, ""},
		{"DNSTXTData.StringArray", Field, 0, ""},
		{"DNSTXTData.StringCount", Field, 0, ""},
		{"DNS_INFO_NO_RECORDS", Const, 4, ""},
		{"DNS_TYPE_A", Const, 0, ""},
		{"DNS_TYPE_A6", Const, 0, ""},
		{"DNS_TYPE_AAAA", Const, 0, ""},
		{"DNS_TYPE_ADDRS", Const, 0, ""},
		{"DNS_TYPE_AFSDB", Const, 0, ""},
		{"DNS_TYPE_ALL", Const, 0, ""},
		{"DNS_TYPE_ANY", Const, 0, ""},
		{"DNS_TYPE_ATMA", Const, 0, ""},
		{"DNS_TYPE_AXFR", Const, 0, ""},
		{"DNS_TYPE_CERT", Const, 0, ""},
		{"DNS_TYPE_CNAME", Const, 0, ""},
		{"DNS_TYPE_DHCID", Const, 0, ""},
		{"DNS_TYPE_DNAME", Const, 0, ""},
		{"DNS_TYPE_DNSKEY", Const, 0, ""},
		{"DNS_TYPE_DS", Const, 0, ""},
		{"DNS_TYPE_EID", Const, 0, ""},
		{"DNS_TYPE_GID", Const, 0, ""},
		{"DNS_TYPE_GPOS", Const, 0, ""},
		{"DNS_TYPE_HINFO", Const, 0, ""},
		{"DNS_TYPE_ISDN", Const, 0, ""},
		{"DNS_TYPE_IXFR", Const, 0, ""},
		{"DNS_TYPE_KEY", Const, 0, ""},
		{"DNS_TYPE_KX", Const, 0, ""},
		{"DNS_TYPE_LOC", Const, 0, ""},
		{"DNS_TYPE_MAILA", Const, 0, ""},
		{"DNS_TYPE_MAILB", Const, 0, ""},
		{"DNS_TYPE_MB", Const, 0, ""},
		{"DNS_TYPE_MD", Const, 0, ""},
		{"DNS_TYPE_MF", Const, 0, ""},
		{"DNS_TYPE_MG", Const, 0, ""},
		{"DNS_TYPE_MINFO", Const, 0, ""},
		{"DNS_TYPE_MR", Const, 0, ""},
		{"DNS_TYPE_MX", Const, 0, ""},
		{"DNS_TYPE_NAPTR", Const, 0, ""},
		{"DNS_TYPE_NBSTAT", Const, 0, ""},
		{"DNS_TYPE_NIMLOC", Const, 0, ""},
		{"DNS_TYPE_NS", Const, 0, ""},
		{"DNS_TYPE_NSAP", Const, 0, ""},
		{"DNS_TYPE_NSAPPTR", Const, 0, ""},
		{"DNS_TYPE_NSEC", Const, 0, ""},
		{"DNS_TYPE_NULL", Const, 0, ""},
		{"DNS_TYPE_NXT", Const, 0, ""},
		{"DNS_TYPE_OPT", Const, 0, ""},
		{"DNS_TYPE_PTR", Const, 0, ""},
		{"DNS_TYPE_PX", Const, 0, ""},
		{"DNS_TYPE_RP", Const, 0, ""},
		{"DNS_TYPE_RRSIG", Const, 0, ""},
		{"DNS_TYPE_RT", Const, 0, ""},
		{"DNS_TYPE_SIG", Const, 0, ""},
		{"DNS_TYPE_SINK", Const, 0, ""},
		{"DNS_TYPE_SOA", Const, 0, ""},
		{"DNS_TYPE_SRV", Const, 0, ""},
		{"DNS_TYPE_TEXT", Const, 0, ""},
		{"DNS_TYPE_TKEY", Const, 0, ""},
		{"DNS_TYPE_TSIG", Const, 0, ""},
		{"DNS_TYPE_UID", Const, 0, ""},
		{"DNS_TYPE_UINFO", Const, 0, ""},
		{"DNS_TYPE_UNSPEC", Const, 0, ""},
		{"DNS_TYPE_WINS", Const, 0, ""},
		{"DNS_TYPE_WINSR", Const, 0, ""},
		{"DNS_TYPE_WKS", Const, 0, ""},
		{"DNS_TYPE_X25", Const, 0, ""},
		{"DT_BLK", Const, 0, ""},
		{"DT_CHR", Const, 0, ""},
		{"DT_DIR", Const, 0, ""},
		{"DT_FIFO", Const, 0, ""},
		{"DT_LNK", Const, 0, ""},
		{"DT_REG", Const, 0, ""},
		{"DT_SOCK", Const, 0, ""},
		{"DT_UNKNOWN", Const, 0, ""},
		{"DT_WHT", Const, 0, ""},
		{"DUPLICATE_CLOSE_SOURCE", Const, 0, ""},
		{"DUPLICATE_SAME_ACCESS", Const, 0, ""},
		{"DeleteFile", Func, 0, ""},
		{"DetachLsf", Func, 0, "func(fd int) error"},
		{"DeviceIoControl", Func, 4, ""},
		{"Dirent", Type, 0, ""},
		{"Dirent.Fileno", Field, 0, ""},
		{"Dirent.Ino", Field, 0, ""},
		{"Dirent.Name", Field, 0, ""},
		{"Dirent.Namlen", Field, 0, ""},
		{"Dirent.Off", Field, 0, ""},
		{"Dirent.Pad0", Field, 12, ""},
		{"Dirent.Pad1", Field, 12, ""},
		{"Dirent.Pad_cgo_0", Field, 0, ""},
		{"Dirent.Reclen", Field, 0, ""},
		{"Dirent.Seekoff", Field, 0, ""},
		{"Dirent.Type", Field, 0, ""},
		{"Dirent.X__d_padding", Field, 3, ""},
		{"DnsNameCompare", Func, 4, ""},
		{"DnsQuery", Func, 0, ""},
		{"DnsRecordListFree", Func, 0, ""},
		{"DnsSectionAdditional", Const, 4, ""},
		{"DnsSectionAnswer", Const, 4, ""},
		{"DnsSectionAuthority", Const, 4, ""},
		{"DnsSectionQuestion", Const, 4, ""},
		{"Dup", Func, 0, "func(oldfd int) (fd int, err error)"},
		{"Dup2", Func, 0, "func(oldfd int, newfd int) (err error)"},
		{"Dup3", Func, 2, "func(oldfd int, newfd int, flags int) (err error)"},
		{"DuplicateHandle", Func, 0, ""},
		{"E2BIG", Const, 0, ""},
		{"EACCES", Const, 0, ""},
		{"EADDRINUSE", Const, 0, ""},
		{"EADDRNOTAVAIL", Const, 0, ""},
		{"EADV", Const, 0, ""},
		{"EAFNOSUPPORT", Const, 0, ""},
		{"EAGAIN", Const, 0, ""},
		{"EALREADY", Const, 0, ""},
		{"EAUTH", Const, 0, ""},
		{"EBADARCH", Const, 0, ""},
		{"EBADE", Const, 0, ""},
		{"EBADEXEC", Const, 0, ""},
		{"EBADF", Const, 0, ""},
		{"EBADFD", Const, 0, ""},
		{"EBADMACHO", Const, 0, ""},
		{"EBADMSG", Const, 0, ""},
		{"EBADR", Const, 0, ""},
		{"EBADRPC", Const, 0, ""},
		{"EBADRQC", Const, 0, ""},
		{"EBADSLT", Const, 0, ""},
		{"EBFONT", Const, 0, ""},
		{"EBUSY", Const, 0, ""},
		{"ECANCELED", Const, 0, ""},
		{"ECAPMODE", Const, 1, ""},
		{"ECHILD", Const, 0, ""},
		{"ECHO", Const, 0, ""},
		{"ECHOCTL", Const, 0, ""},
		{"ECHOE", Const, 0, ""},
		{"ECHOK", Const, 0, ""},
		{"ECHOKE", Const, 0, ""},
		{"ECHONL", Const, 0, ""},
		{"ECHOPRT", Const, 0, ""},
		{"ECHRNG", Const, 0, ""},
		{"ECOMM", Const, 0, ""},
		{"ECONNABORTED", Const, 0, ""},
		{"ECONNREFUSED", Const, 0, ""},
		{"ECONNRESET", Const, 0, ""},
		{"EDEADLK", Const, 0, ""},
		{"EDEADLOCK", Const, 0, ""},
		{"EDESTADDRREQ", Const, 0, ""},
		{"EDEVERR", Const, 0, ""},
		{"EDOM", Const, 0, ""},
		{"EDOOFUS", Const, 0, ""},
		{"EDOTDOT", Const, 0, ""},
		{"EDQUOT", Const, 0, ""},
		{"EEXIST", Const, 0, ""},
		{"EFAULT", Const, 0, ""},
		{"EFBIG", Const, 0, ""},
		{"EFER_LMA", Const, 1, ""},
		{"EFER_LME", Const, 1, ""},
		{"EFER_NXE", Const, 1, ""},
		{"EFER_SCE", Const, 1, ""},
		{"EFTYPE", Const, 0, ""},
		{"EHOSTDOWN", Const, 0, ""},
		{"EHOSTUNREACH", Const, 0, ""},
		{"EHWPOISON", Const, 0, ""},
		{"EIDRM", Const, 0, ""},
		{"EILSEQ", Const, 0, ""},
		{"EINPROGRESS", Const, 0, ""},
		{"EINTR", Const, 0, ""},
		{"EINVAL", Const, 0, ""},
		{"EIO", Const, 0, ""},
		{"EIPSEC", Const, 1, ""},
		{"EISCONN", Const, 0, ""},
		{"EISDIR", Const, 0, ""},
		{"EISNAM", Const, 0, ""},
		{"EKEYEXPIRED", Const, 0, ""},
		{"EKEYREJECTED", Const, 0, ""},
		{"EKEYREVOKED", Const, 0, ""},
		{"EL2HLT", Const, 0, ""},
		{"EL2NSYNC", Const, 0, ""},
		{"EL3HLT", Const, 0, ""},
		{"EL3RST", Const, 0, ""},
		{"ELAST", Const, 0, ""},
		{"ELF_NGREG", Const, 0, ""},
		{"ELF_PRARGSZ", Const, 0, ""},
		{"ELIBACC", Const, 0, ""},
		{"ELIBBAD", Const, 0, ""},
		{"ELIBEXEC", Const, 0, ""},
		{"ELIBMAX", Const, 0, ""},
		{"ELIBSCN", Const, 0, ""},
		{"ELNRNG", Const, 0, ""},
		{"ELOOP", Const, 0, ""},
		{"EMEDIUMTYPE", Const, 0, ""},
		{"EMFILE", Const, 0, ""},
		{"EMLINK", Const, 0, ""},
		{"EMSGSIZE", Const, 0, ""},
		{"EMT_TAGOVF", Const, 1, ""},
		{"EMULTIHOP", Const, 0, ""},
		{"EMUL_ENABLED", Const, 1, ""},
		{"EMUL_LINUX", Const, 1, ""},
		{"EMUL_LINUX32", Const, 1, ""},
		{"EMUL_MAXID", Const, 1, ""},
		{"EMUL_NATIVE", Const, 1, ""},
		{"ENAMETOOLONG", Const, 0, ""},
		{"ENAVAIL", Const, 0, ""},
		{"ENDRUNDISC", Const, 1, ""},
		{"ENEEDAUTH", Const, 0, ""},
		{"ENETDOWN", Const, 0, ""},
		{"ENETRESET", Const, 0, ""},
		{"ENETUNREACH", Const, 0, ""},
		{"ENFILE", Const, 0, ""},
		{"ENOANO", Const, 0, ""},
		{"ENOATTR", Const, 0, ""},
		{"ENOBUFS", Const, 0, ""},
		{"ENOCSI", Const, 0, ""},
		{"ENODATA", Const, 0, ""},
		{"ENODEV", Const, 0, ""},
		{"ENOENT", Const, 0, ""},
		{"ENOEXEC", Const, 0, ""},
		{"ENOKEY", Const, 0, ""},
		{"ENOLCK", Const, 0, ""},
		{"ENOLINK", Const, 0, ""},
		{"ENOMEDIUM", Const, 0, ""},
		{"ENOMEM", Const, 0, ""},
		{"ENOMSG", Const, 0, ""},
		{"ENONET", Const, 0, ""},
		{"ENOPKG", Const, 0, ""},
		{"ENOPOLICY", Const, 0, ""},
		{"ENOPROTOOPT", Const, 0, ""},
		{"ENOSPC", Const, 0, ""},
		{"ENOSR", Const, 0, ""},
		{"ENOSTR", Const, 0, ""},
		{"ENOSYS", Const, 0, ""},
		{"ENOTBLK", Const, 0, ""},
		{"ENOTCAPABLE", Const, 0, ""},
		{"ENOTCONN", Const, 0, ""},
		{"ENOTDIR", Const, 0, ""},
		{"ENOTEMPTY", Const, 0, ""},
		{"ENOTNAM", Const, 0, ""},
		{"ENOTRECOVERABLE", Const, 0, ""},
		{"ENOTSOCK", Const, 0, ""},
		{"ENOTSUP", Const, 0, ""},
		{"ENOTTY", Const, 0, ""},
		{"ENOTUNIQ", Const, 0, ""},
		{"ENXIO", Const, 0, ""},
		{"EN_SW_CTL_INF", Const, 1, ""},
		{"EN_SW_CTL_PREC", Const, 1, ""},
		{"EN_SW_CTL_ROUND", Const, 1, ""},
		{"EN_SW_DATACHAIN", Const, 1, ""},
		{"EN_SW_DENORM", Const, 1, ""},
		{"EN_SW_INVOP", Const, 1, ""},
		{"EN_SW_OVERFLOW", Const, 1, ""},
		{"EN_SW_PRECLOSS", Const, 1, ""},
		{"EN_SW_UNDERFLOW", Const, 1, ""},
		{"EN_SW_ZERODIV", Const, 1, ""},
		{"EOPNOTSUPP", Const, 0, ""},
		{"EOVERFLOW", Const, 0, ""},
		{"EOWNERDEAD", Const, 0, ""},
		{"EPERM", Const, 0, ""},
		{"EPFNOSUPPORT", Const, 0, ""},
		{"EPIPE", Const, 0, ""},
		{"EPOLLERR", Const, 0, ""},
		{"EPOLLET", Const, 0, ""},
		{"EPOLLHUP", Const, 0, ""},
		{"EPOLLIN", Const, 0, ""},
		{"EPOLLMSG", Const, 0, ""},
		{"EPOLLONESHOT", Const, 0, ""},
		{"EPOLLOUT", Const, 0, ""},
		{"EPOLLPRI", Const, 0, ""},
		{"EPOLLRDBAND", Const, 0, ""},
		{"EPOLLRDHUP", Const, 0, ""},
		{"EPOLLRDNORM", Const, 0, ""},
		{"EPOLLWRBAND", Const, 0, ""},
		{"EPOLLWRNORM", Const, 0, ""},
		{"EPOLL_CLOEXEC", Const, 0, ""},
		{"EPOLL_CTL_ADD", Const, 0, ""},
		{"EPOLL_CTL_DEL", Const, 0, ""},
		{"EPOLL_CTL_MOD", Const, 0, ""},
		{"EPOLL_NONBLOCK", Const, 0, ""},
		{"EPROCLIM", Const, 0, ""},
		{"EPROCUNAVAIL", Const, 0, ""},
		{"EPROGMISMATCH", Const, 0, ""},
		{"EPROGUNAVAIL", Const, 0, ""},
		{"EPROTO", Const, 0, ""},
		{"EPROTONOSUPPORT", Const, 0, ""},
		{"EPROTOTYPE", Const, 0, ""},
		{"EPWROFF", Const, 0, ""},
		{"EQFULL", Const, 16, ""},
		{"ERANGE", Const, 0, ""},
		{"EREMCHG", Const, 0, ""},
		{"EREMOTE", Const, 0, ""},
		{"EREMOTEIO", Const, 0, ""},
		{"ERESTART", Const, 0, ""},
		{"ERFKILL", Const, 0, ""},
		{"EROFS", Const, 0, ""},
		{"ERPCMISMATCH", Const, 0, ""},
		{"ERROR_ACCESS_DENIED", Const, 0, ""},
		{"ERROR_ALREADY_EXISTS", Const, 0, ""},
		{"ERROR_BROKEN_PIPE", Const, 0, ""},
		{"ERROR_BUFFER_OVERFLOW", Const, 0, ""},
		{"ERROR_DIR_NOT_EMPTY", Const, 8, ""},
		{"ERROR_ENVVAR_NOT_FOUND", Const, 0, ""},
		{"ERROR_FILE_EXISTS", Const, 0, ""},
		{"ERROR_FILE_NOT_FOUND", Const, 0, ""},
		{"ERROR_HANDLE_EOF", Const, 2, ""},
		{"ERROR_INSUFFICIENT_BUFFER", Const, 0, ""},
		{"ERROR_IO_PENDING", Const, 0, ""},
		{"ERROR_MOD_NOT_FOUND", Const, 0, ""},
		{"ERROR_MORE_DATA", Const, 3, ""},
		{"ERROR_NETNAME_DELETED", Const, 3, ""},
		{"ERROR_NOT_FOUND", Const, 1, ""},
		{"ERROR_NO_MORE_FILES", Const, 0, ""},
		{"ERROR_OPERATION_ABORTED", Const, 0, ""},
		{"ERROR_PATH_NOT_FOUND", Const, 0, ""},
		{"ERROR_PRIVILEGE_NOT_HELD", Const, 4, ""},
		{"ERROR_PROC_NOT_FOUND", Const, 0, ""},
		{"ESHLIBVERS", Const, 0, ""},
		{"ESHUTDOWN", Const, 0, ""},
		{"ESOCKTNOSUPPORT", Const, 0, ""},
		{"ESPIPE", Const, 0, ""},
		{"ESRCH", Const, 0, ""},
		{"ESRMNT", Const, 0, ""},
		{"ESTALE", Const, 0, ""},
		{"ESTRPIPE", Const, 0, ""},
		{"ETHERCAP_JUMBO_MTU", Const, 1, ""},
		{"ETHERCAP_VLAN_HWTAGGING", Const, 1, ""},
		{"ETHERCAP_VLAN_MTU", Const, 1, ""},
		{"ETHERMIN", Const, 1, ""},
		{"ETHERMTU", Const, 1, ""},
		{"ETHERMTU_JUMBO", Const, 1, ""},
		{"ETHERTYPE_8023", Const, 1, ""},
		{"ETHERTYPE_AARP", Const, 1, ""},
		{"ETHERTYPE_ACCTON", Const, 1, ""},
		{"ETHERTYPE_AEONIC", Const, 1, ""},
		{"ETHERTYPE_ALPHA", Const, 1, ""},
		{"ETHERTYPE_AMBER", Const, 1, ""},
		{"ETHERTYPE_AMOEBA", Const, 1, ""},
		{"ETHERTYPE_AOE", Const, 1, ""},
		{"ETHERTYPE_APOLLO", Const, 1, ""},
		{"ETHERTYPE_APOLLODOMAIN", Const, 1, ""},
		{"ETHERTYPE_APPLETALK", Const, 1, ""},
		{"ETHERTYPE_APPLITEK", Const, 1, ""},
		{"ETHERTYPE_ARGONAUT", Const, 1, ""},
		{"ETHERTYPE_ARP", Const, 1, ""},
		{"ETHERTYPE_AT", Const, 1, ""},
		{"ETHERTYPE_ATALK", Const, 1, ""},
		{"ETHERTYPE_ATOMIC", Const, 1, ""},
		{"ETHERTYPE_ATT", Const, 1, ""},
		{"ETHERTYPE_ATTSTANFORD", Const, 1, ""},
		{"ETHERTYPE_AUTOPHON", Const, 1, ""},
		{"ETHERTYPE_AXIS", Const, 1, ""},
		{"ETHERTYPE_BCLOOP", Const, 1, ""},
		{"ETHERTYPE_BOFL", Const, 1, ""},
		{"ETHERTYPE_CABLETRON", Const, 1, ""},
		{"ETHERTYPE_CHAOS", Const, 1, ""},
		{"ETHERTYPE_COMDESIGN", Const, 1, ""},
		{"ETHERTYPE_COMPUGRAPHIC", Const, 1, ""},
		{"ETHERTYPE_COUNTERPOINT", Const, 1, ""},
		{"ETHERTYPE_CRONUS", Const, 1, ""},
		{"ETHERTYPE_CRONUSVLN", Const, 1, ""},
		{"ETHERTYPE_DCA", Const, 1, ""},
		{"ETHERTYPE_DDE", Const, 1, ""},
		{"ETHERTYPE_DEBNI", Const, 1, ""},
		{"ETHERTYPE_DECAM", Const, 1, ""},
		{"ETHERTYPE_DECCUST", Const, 1, ""},
		{"ETHERTYPE_DECDIAG", Const, 1, ""},
		{"ETHERTYPE_DECDNS", Const, 1, ""},
		{"ETHERTYPE_DECDTS", Const, 1, ""},
		{"ETHERTYPE_DECEXPER", Const, 1, ""},
		{"ETHERTYPE_DECLAST", Const, 1, ""},
		{"ETHERTYPE_DECLTM", Const, 1, ""},
		{"ETHERTYPE_DECMUMPS", Const, 1, ""},
		{"ETHERTYPE_DECNETBIOS", Const, 1, ""},
		{"ETHERTYPE_DELTACON", Const, 1, ""},
		{"ETHERTYPE_DIDDLE", Const, 1, ""},
		{"ETHERTYPE_DLOG1", Const, 1, ""},
		{"ETHERTYPE_DLOG2", Const, 1, ""},
		{"ETHERTYPE_DN", Const, 1, ""},
		{"ETHERTYPE_DOGFIGHT", Const, 1, ""},
		{"ETHERTYPE_DSMD", Const, 1, ""},
		{"ETHERTYPE_ECMA", Const, 1, ""},
		{"ETHERTYPE_ENCRYPT", Const, 1, ""},
		{"ETHERTYPE_ES", Const, 1, ""},
		{"ETHERTYPE_EXCELAN", Const, 1, ""},
		{"ETHERTYPE_EXPERDATA", Const, 1, ""},
		{"ETHERTYPE_FLIP", Const, 1, ""},
		{"ETHERTYPE_FLOWCONTROL", Const, 1, ""},
		{"ETHERTYPE_FRARP", Const, 1, ""},
		{"ETHERTYPE_GENDYN", Const, 1, ""},
		{"ETHERTYPE_HAYES", Const, 1, ""},
		{"ETHERTYPE_HIPPI_FP", Const, 1, ""},
		{"ETHERTYPE_HITACHI", Const, 1, ""},
		{"ETHERTYPE_HP", Const, 1, ""},
		{"ETHERTYPE_IEEEPUP", Const, 1, ""},
		{"ETHERTYPE_IEEEPUPAT", Const, 1, ""},
		{"ETHERTYPE_IMLBL", Const, 1, ""},
		{"ETHERTYPE_IMLBLDIAG", Const, 1, ""},
		{"ETHERTYPE_IP", Const, 1, ""},
		{"ETHERTYPE_IPAS", Const, 1, ""},
		{"ETHERTYPE_IPV6", Const, 1, ""},
		{"ETHERTYPE_IPX", Const, 1, ""},
		{"ETHERTYPE_IPXNEW", Const, 1, ""},
		{"ETHERTYPE_KALPANA", Const, 1, ""},
		{"ETHERTYPE_LANBRIDGE", Const, 1, ""},
		{"ETHERTYPE_LANPROBE", Const, 1, ""},
		{"ETHERTYPE_LAT", Const, 1, ""},
		{"ETHERTYPE_LBACK", Const, 1, ""},
		{"ETHERTYPE_LITTLE", Const, 1, ""},
		{"ETHERTYPE_LLDP", Const, 1, ""},
		{"ETHERTYPE_LOGICRAFT", Const, 1, ""},
		{"ETHERTYPE_LOOPBACK", Const, 1, ""},
		{"ETHERTYPE_MATRA", Const, 1, ""},
		{"ETHERTYPE_MAX", Const, 1, ""},
		{"ETHERTYPE_MERIT", Const, 1, ""},
		{"ETHERTYPE_MICP", Const, 1, ""},
		{"ETHERTYPE_MOPDL", Const, 1, ""},
		{"ETHERTYPE_MOPRC", Const, 1, ""},
		{"ETHERTYPE_MOTOROLA", Const, 1, ""},
		{"ETHERTYPE_MPLS", Const, 1, ""},
		{"ETHERTYPE_MPLS_MCAST", Const, 1, ""},
		{"ETHERTYPE_MUMPS", Const, 1, ""},
		{"ETHERTYPE_NBPCC", Const, 1, ""},
		{"ETHERTYPE_NBPCLAIM", Const, 1, ""},
		{"ETHERTYPE_NBPCLREQ", Const, 1, ""},
		{"ETHERTYPE_NBPCLRSP", Const, 1, ""},
		{"ETHERTYPE_NBPCREQ", Const, 1, ""},
		{"ETHERTYPE_NBPCRSP", Const, 1, ""},
		{"ETHERTYPE_NBPDG", Const, 1, ""},
		{"ETHERTYPE_NBPDGB", Const, 1, ""},
		{"ETHERTYPE_NBPDLTE", Const, 1, ""},
		{"ETHERTYPE_NBPRAR", Const, 1, ""},
		{"ETHERTYPE_NBPRAS", Const, 1, ""},
		{"ETHERTYPE_NBPRST", Const, 1, ""},
		{"ETHERTYPE_NBPSCD", Const, 1, ""},
		{"ETHERTYPE_NBPVCD", Const, 1, ""},
		{"ETHERTYPE_NBS", Const, 1, ""},
		{"ETHERTYPE_NCD", Const, 1, ""},
		{"ETHERTYPE_NESTAR", Const, 1, ""},
		{"ETHERTYPE_NETBEUI", Const, 1, ""},
		{"ETHERTYPE_NOVELL", Const, 1, ""},
		{"ETHERTYPE_NS", Const, 1, ""},
		{"ETHERTYPE_NSAT", Const, 1, ""},
		{"ETHERTYPE_NSCOMPAT", Const, 1, ""},
		{"ETHERTYPE_NTRAILER", Const, 1, ""},
		{"ETHERTYPE_OS9", Const, 1, ""},
		{"ETHERTYPE_OS9NET", Const, 1, ""},
		{"ETHERTYPE_PACER", Const, 1, ""},
		{"ETHERTYPE_PAE", Const, 1, ""},
		{"ETHERTYPE_PCS", Const, 1, ""},
		{"ETHERTYPE_PLANNING", Const, 1, ""},
		{"ETHERTYPE_PPP", Const, 1, ""},
		{"ETHERTYPE_PPPOE", Const, 1, ""},
		{"ETHERTYPE_PPPOEDISC", Const, 1, ""},
		{"ETHERTYPE_PRIMENTS", Const, 1, ""},
		{"ETHERTYPE_PUP", Const, 1, ""},
		{"ETHERTYPE_PUPAT", Const, 1, ""},
		{"ETHERTYPE_QINQ", Const, 1, ""},
		{"ETHERTYPE_RACAL", Const, 1, ""},
		{"ETHERTYPE_RATIONAL", Const, 1, ""},
		{"ETHERTYPE_RAWFR", Const, 1, ""},
		{"ETHERTYPE_RCL", Const, 1, ""},
		{"ETHERTYPE_RDP", Const, 1, ""},
		{"ETHERTYPE_RETIX", Const, 1, ""},
		{"ETHERTYPE_REVARP", Const, 1, ""},
		{"ETHERTYPE_SCA", Const, 1, ""},
		{"ETHERTYPE_SECTRA", Const, 1, ""},
		{"ETHERTYPE_SECUREDATA", Const, 1, ""},
		{"ETHERTYPE_SGITW", Const, 1, ""},
		{"ETHERTYPE_SG_BOUNCE", Const, 1, ""},
		{"ETHERTYPE_SG_DIAG", Const, 1, ""},
		{"ETHERTYPE_SG_NETGAMES", Const, 1, ""},
		{"ETHERTYPE_SG_RESV", Const, 1, ""},
		{"ETHERTYPE_SIMNET", Const, 1, ""},
		{"ETHERTYPE_SLOW", Const, 1, ""},
		{"ETHERTYPE_SLOWPROTOCOLS", Const, 1, ""},
		{"ETHERTYPE_SNA", Const, 1, ""},
		{"ETHERTYPE_SNMP", Const, 1, ""},
		{"ETHERTYPE_SONIX", Const, 1, ""},
		{"ETHERTYPE_SPIDER", Const, 1, ""},
		{"ETHERTYPE_SPRITE", Const, 1, ""},
		{"ETHERTYPE_STP", Const, 1, ""},
		{"ETHERTYPE_TALARIS", Const, 1, ""},
		{"ETHERTYPE_TALARISMC", Const, 1, ""},
		{"ETHERTYPE_TCPCOMP", Const, 1, ""},
		{"ETHERTYPE_TCPSM", Const, 1, ""},
		{"ETHERTYPE_TEC", Const, 1, ""},
		{"ETHERTYPE_TIGAN", Const, 1, ""},
		{"ETHERTYPE_TRAIL", Const, 1, ""},
		{"ETHERTYPE_TRANSETHER", Const, 1, ""},
		{"ETHERTYPE_TYMSHARE", Const, 1, ""},
		{"ETHERTYPE_UBBST", Const, 1, ""},
		{"ETHERTYPE_UBDEBUG", Const, 1, ""},
		{"ETHERTYPE_UBDIAGLOOP", Const, 1, ""},
		{"ETHERTYPE_UBDL", Const, 1, ""},
		{"ETHERTYPE_UBNIU", Const, 1, ""},
		{"ETHERTYPE_UBNMC", Const, 1, ""},
		{"ETHERTYPE_VALID", Const, 1, ""},
		{"ETHERTYPE_VARIAN", Const, 1, ""},
		{"ETHERTYPE_VAXELN", Const, 1, ""},
		{"ETHERTYPE_VEECO", Const, 1, ""},
		{"ETHERTYPE_VEXP", Const, 1, ""},
		{"ETHERTYPE_VGLAB", Const, 1, ""},
		{"ETHERTYPE_VINES", Const, 1, ""},
		{"ETHERTYPE_VINESECHO", Const, 1, ""},
		{"ETHERTYPE_VINESLOOP", Const, 1, ""},
		{"ETHERTYPE_VITAL", Const, 1, ""},
		{"ETHERTYPE_VLAN", Const, 1, ""},
		{"ETHERTYPE_VLTLMAN", Const, 1, ""},
		{"ETHERTYPE_VPROD", Const, 1, ""},
		{"ETHERTYPE_VURESERVED", Const, 1, ""},
		{"ETHERTYPE_WATERLOO", Const, 1, ""},
		{"ETHERTYPE_WELLFLEET", Const, 1, ""},
		{"ETHERTYPE_X25", Const, 1, ""},
		{"ETHERTYPE_X75", Const, 1, ""},
		{"ETHERTYPE_XNSSM", Const, 1, ""},
		{"ETHERTYPE_XTP", Const, 1, ""},
		{"ETHER_ADDR_LEN", Const, 1, ""},
		{"ETHER_ALIGN", Const, 1, ""},
		{"ETHER_CRC_LEN", Const, 1, ""},
		{"ETHER_CRC_POLY_BE", Const, 1, ""},
		{"ETHER_CRC_POLY_LE", Const, 1, ""},
		{"ETHER_HDR_LEN", Const, 1, ""},
		{"ETHER_MAX_DIX_LEN", Const, 1, ""},
		{"ETHER_MAX_LEN", Const, 1, ""},
		{"ETHER_MAX_LEN_JUMBO", Const, 1, ""},
		{"ETHER_MIN_LEN", Const, 1, ""},
		{"ETHER_PPPOE_ENCAP_LEN", Const, 1, ""},
		{"ETHER_TYPE_LEN", Const, 1, ""},
		{"ETHER_VLAN_ENCAP_LEN", Const, 1, ""},
		{"ETH_P_1588", Const, 0, ""},
		{"ETH_P_8021Q", Const, 0, ""},
		{"ETH_P_802_2", Const, 0, ""},
		{"ETH_P_802_3", Const, 0, ""},
		{"ETH_P_AARP", Const, 0, ""},
		{"ETH_P_ALL", Const, 0, ""},
		{"ETH_P_AOE", Const, 0, ""},
		{"ETH_P_ARCNET", Const, 0, ""},
		{"ETH_P_ARP", Const, 0, ""},
		{"ETH_P_ATALK", Const, 0, ""},
		{"ETH_P_ATMFATE", Const, 0, ""},
		{"ETH_P_ATMMPOA", Const, 0, ""},
		{"ETH_P_AX25", Const, 0, ""},
		{"ETH_P_BPQ", Const, 0, ""},
		{"ETH_P_CAIF", Const, 0, ""},
		{"ETH_P_CAN", Const, 0, ""},
		{"ETH_P_CONTROL", Const, 0, ""},
		{"ETH_P_CUST", Const, 0, ""},
		{"ETH_P_DDCMP", Const, 0, ""},
		{"ETH_P_DEC", Const, 0, ""},
		{"ETH_P_DIAG", Const, 0, ""},
		{"ETH_P_DNA_DL", Const, 0, ""},
		{"ETH_P_DNA_RC", Const, 0, ""},
		{"ETH_P_DNA_RT", Const, 0, ""},
		{"ETH_P_DSA", Const, 0, ""},
		{"ETH_P_ECONET", Const, 0, ""},
		{"ETH_P_EDSA", Const, 0, ""},
		{"ETH_P_FCOE", Const, 0, ""},
		{"ETH_P_FIP", Const, 0, ""},
		{"ETH_P_HDLC", Const, 0, ""},
		{"ETH_P_IEEE802154", Const, 0, ""},
		{"ETH_P_IEEEPUP", Const, 0, ""},
		{"ETH_P_IEEEPUPAT", Const, 0, ""},
		{"ETH_P_IP", Const, 0, ""},
		{"ETH_P_IPV6", Const, 0, ""},
		{"ETH_P_IPX", Const, 0, ""},
		{"ETH_P_IRDA", Const, 0, ""},
		{"ETH_P_LAT", Const, 0, ""},
		{"ETH_P_LINK_CTL", Const, 0, ""},
		{"ETH_P_LOCALTALK", Const, 0, ""},
		{"ETH_P_LOOP", Const, 0, ""},
		{"ETH_P_MOBITEX", Const, 0, ""},
		{"ETH_P_MPLS_MC", Const, 0, ""},
		{"ETH_P_MPLS_UC", Const, 0, ""},
		{"ETH_P_PAE", Const, 0, ""},
		{"ETH_P_PAUSE", Const, 0, ""},
		{"ETH_P_PHONET", Const, 0, ""},
		{"ETH_P_PPPTALK", Const, 0, ""},
		{"ETH_P_PPP_DISC", Const, 0, ""},
		{"ETH_P_PPP_MP", Const, 0, ""},
		{"ETH_P_PPP_SES", Const, 0, ""},
		{"ETH_P_PUP", Const, 0, ""},
		{"ETH_P_PUPAT", Const, 0, ""},
		{"ETH_P_RARP", Const, 0, ""},
		{"ETH_P_SCA", Const, 0, ""},
		{"ETH_P_SLOW", Const, 0, ""},
		{"ETH_P_SNAP", Const, 0, ""},
		{"ETH_P_TEB", Const, 0, ""},
		{"ETH_P_TIPC", Const, 0, ""},
		{"ETH_P_TRAILER", Const, 0, ""},
		{"ETH_P_TR_802_2", Const, 0, ""},
		{"ETH_P_WAN_PPP", Const, 0, ""},
		{"ETH_P_WCCP", Const, 0, ""},
		{"ETH_P_X25", Const, 0, ""},
		{"ETIME", Const, 0, ""},
		{"ETIMEDOUT", Const, 0, ""},
		{"ETOOMANYREFS", Const, 0, ""},
		{"ETXTBSY", Const, 0, ""},
		{"EUCLEAN", Const, 0, ""},
		{"EUNATCH", Const, 0, ""},
		{"EUSERS", Const, 0, ""},
		{"EVFILT_AIO", Const, 0, ""},
		{"EVFILT_FS", Const, 0, ""},
		{"EVFILT_LIO", Const, 0, ""},
		{"EVFILT_MACHPORT", Const, 0, ""},
		{"EVFILT_PROC", Const, 0, ""},
		{"EVFILT_READ", Const, 0, ""},
		{"EVFILT_SIGNAL", Const, 0, ""},
		{"EVFILT_SYSCOUNT", Const, 0, ""},
		{"EVFILT_THREADMARKER", Const, 0, ""},
		{"EVFILT_TIMER", Const, 0, ""},
		{"EVFILT_USER", Const, 0, ""},
		{"EVFILT_VM", Const, 0, ""},
		{"EVFILT_VNODE", Const, 0, ""},
		{"EVFILT_WRITE", Const, 0, ""},
		{"EV_ADD", Const, 0, ""},
		{"EV_CLEAR", Const, 0, ""},
		{"EV_DELETE", Const, 0, ""},
		{"EV_DISABLE", Const, 0, ""},
		{"EV_DISPATCH", Const, 0, ""},
		{"EV_DROP", Const, 3, ""},
		{"EV_ENABLE", Const, 0, ""},
		{"EV_EOF", Const, 0, ""},
		{"EV_ERROR", Const, 0, ""},
		{"EV_FLAG0", Const, 0, ""},
		{"EV_FLAG1", Const, 0, ""},
		{"EV_ONESHOT", Const, 0, ""},
		{"EV_OOBAND", Const, 0, ""},
		{"EV_POLL", Const, 0, ""},
		{"EV_RECEIPT", Const, 0, ""},
		{"EV_SYSFLAGS", Const, 0, ""},
		{"EWINDOWS", Const, 0, ""},
		{"EWOULDBLOCK", Const, 0, ""},
		{"EXDEV", Const, 0, ""},
		{"EXFULL", Const, 0, ""},
		{"EXTA", Const, 0, ""},
		{"EXTB", Const, 0, ""},
		{"EXTPROC", Const, 0, ""},
		{"Environ", Func, 0, "func() []string"},
		{"EpollCreate", Func, 0, "func(size int) (fd int, err error)"},
		{"EpollCreate1", Func, 0, "func(flag int) (fd int, err error)"},
		{"EpollCtl", Func, 0, "func(epfd int, op int, fd int, event *EpollEvent) (err error)"},
		{"EpollEvent", Type, 0, ""},
		{"EpollEvent.Events", Field, 0, ""},
		{"EpollEvent.Fd", Field, 0, ""},
		{"EpollEvent.Pad", Field, 0, ""},
		{"EpollEvent.PadFd", Field, 0, ""},
		{"EpollWait", Func, 0, "func(epfd int, events []EpollEvent, msec int) (n int, err error)"},
		{"Errno", Type, 0, ""},
		{"EscapeArg", Func, 0, ""},
		{"Exchangedata", Func, 0, ""},
		{"Exec", Func, 0, "func(argv0 string, argv []string, envv []string) (err error)"},
		{"Exit", Func, 0, "func(code int)"},
		{"ExitProcess", Func, 0, ""},
		{"FD_CLOEXEC", Const, 0, ""},
		{"FD_SETSIZE", Const, 0, ""},
		{"FILE_ACTION_ADDED", Const, 0, ""},
		{"FILE_ACTION_MODIFIED", Const, 0, ""},
		{"FILE_ACTION_REMOVED", Const, 0, ""},
		{"FILE_ACTION_RENAMED_NEW_NAME", Const, 0, ""},
		{"FILE_ACTION_RENAMED_OLD_NAME", Const, 0, ""},
		{"FILE_APPEND_DATA", Const, 0, ""},
		{"FILE_ATTRIBUTE_ARCHIVE", Const, 0, ""},
		{"FILE_ATTRIBUTE_DIRECTORY", Const, 0, ""},
		{"FILE_ATTRIBUTE_HIDDEN", Const, 0, ""},
		{"FILE_ATTRIBUTE_NORMAL", Const, 0, ""},
		{"FILE_ATTRIBUTE_READONLY", Const, 0, ""},
		{"FILE_ATTRIBUTE_REPARSE_POINT", Const, 4, ""},
		{"FILE_ATTRIBUTE_SYSTEM", Const, 0, ""},
		{"FILE_BEGIN", Const, 0, ""},
		{"FILE_CURRENT", Const, 0, ""},
		{"FILE_END", Const, 0, ""},
		{"FILE_FLAG_BACKUP_SEMANTICS", Const, 0, ""},
		{"FILE_FLAG_OPEN_REPARSE_POINT", Const, 4, ""},
		{"FILE_FLAG_OVERLAPPED", Const, 0, ""},
		{"FILE_LIST_DIRECTORY", Const, 0, ""},
		{"FILE_MAP_COPY", Const, 0, ""},
		{"FILE_MAP_EXECUTE", Const, 0, ""},
		{"FILE_MAP_READ", Const, 0, ""},
		{"FILE_MAP_WRITE", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_ATTRIBUTES", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_CREATION", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_DIR_NAME", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_FILE_NAME", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_LAST_ACCESS", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_LAST_WRITE", Const, 0, ""},
		{"FILE_NOTIFY_CHANGE_SIZE", Const, 0, ""},
		{"FILE_SHARE_DELETE", Const, 0, ""},
		{"FILE_SHARE_READ", Const, 0, ""},
		{"FILE_SHARE_WRITE", Const, 0, ""},
		{"FILE_SKIP_COMPLETION_PORT_ON_SUCCESS", Const, 2, ""},
		{"FILE_SKIP_SET_EVENT_ON_HANDLE", Const, 2, ""},
		{"FILE_TYPE_CHAR", Const, 0, ""},
		{"FILE_TYPE_DISK", Const, 0, ""},
		{"FILE_TYPE_PIPE", Const, 0, ""},
		{"FILE_TYPE_REMOTE", Const, 0, ""},
		{"FILE_TYPE_UNKNOWN", Const, 0, ""},
		{"FILE_WRITE_ATTRIBUTES", Const, 0, ""},
		{"FLUSHO", Const, 0, ""},
		{"FORMAT_MESSAGE_ALLOCATE_BUFFER", Const, 0, ""},
		{"FORMAT_MESSAGE_ARGUMENT_ARRAY", Const, 0, ""},
		{"FORMAT_MESSAGE_FROM_HMODULE", Const, 0, ""},
		{"FORMAT_MESSAGE_FROM_STRING", Const, 0, ""},
		{"FORMAT_MESSAGE_FROM_SYSTEM", Const, 0, ""},
		{"FORMAT_MESSAGE_IGNORE_INSERTS", Const, 0, ""},
		{"FORMAT_MESSAGE_MAX_WIDTH_MASK", Const, 0, ""},
		{"FSCTL_GET_REPARSE_POINT", Const, 4, ""},
		{"F_ADDFILESIGS", Const, 0, ""},
		{"F_ADDSIGS", Const, 0, ""},
		{"F_ALLOCATEALL", Const, 0, ""},
		{"F_ALLOCATECONTIG", Const, 0, ""},
		{"F_CANCEL", Const, 0, ""},
		{"F_CHKCLEAN", Const, 0, ""},
		{"F_CLOSEM", Const, 1, ""},
		{"F_DUP2FD", Const, 0, ""},
		{"F_DUP2FD_CLOEXEC", Const, 1, ""},
		{"F_DUPFD", Const, 0, ""},
		{"F_DUPFD_CLOEXEC", Const, 0, ""},
		{"F_EXLCK", Const, 0, ""},
		{"F_FINDSIGS", Const, 16, ""},
		{"F_FLUSH_DATA", Const, 0, ""},
		{"F_FREEZE_FS", Const, 0, ""},
		{"F_FSCTL", Const, 1, ""},
		{"F_FSDIRMASK", Const, 1, ""},
		{"F_FSIN", Const, 1, ""},
		{"F_FSINOUT", Const, 1, ""},
		{"F_FSOUT", Const, 1, ""},
		{"F_FSPRIV", Const, 1, ""},
		{"F_FSVOID", Const, 1, ""},
		{"F_FULLFSYNC", Const, 0, ""},
		{"F_GETCODEDIR", Const, 16, ""},
		{"F_GETFD", Const, 0, ""},
		{"F_GETFL", Const, 0, ""},
		{"F_GETLEASE", Const, 0, ""},
		{"F_GETLK", Const, 0, ""},
		{"F_GETLK64", Const, 0, ""},
		{"F_GETLKPID", Const, 0, ""},
		{"F_GETNOSIGPIPE", Const, 0, ""},
		{"F_GETOWN", Const, 0, ""},
		{"F_GETOWN_EX", Const, 0, ""},
		{"F_GETPATH", Const, 0, ""},
		{"F_GETPATH_MTMINFO", Const, 0, ""},
		{"F_GETPIPE_SZ", Const, 0, ""},
		{"F_GETPROTECTIONCLASS", Const, 0, ""},
		{"F_GETPROTECTIONLEVEL", Const, 16, ""},
		{"F_GETSIG", Const, 0, ""},
		{"F_GLOBAL_NOCACHE", Const, 0, ""},
		{"F_LOCK", Const, 0, ""},
		{"F_LOG2PHYS", Const, 0, ""},
		{"F_LOG2PHYS_EXT", Const, 0, ""},
		{"F_MARKDEPENDENCY", Const, 0, ""},
		{"F_MAXFD", Const, 1, ""},
		{"F_NOCACHE", Const, 0, ""},
		{"F_NODIRECT", Const, 0, ""},
		{"F_NOTIFY", Const, 0, ""},
		{"F_OGETLK", Const, 0, ""},
		{"F_OK", Const, 0, ""},
		{"F_OSETLK", Const, 0, ""},
		{"F_OSETLKW", Const, 0, ""},
		{"F_PARAM_MASK", Const, 1, ""},
		{"F_PARAM_MAX", Const, 1, ""},
		{"F_PATHPKG_CHECK", Const, 0, ""},
		{"F_PEOFPOSMODE", Const, 0, ""},
		{"F_PREALLOCATE", Const, 0, ""},
		{"F_RDADVISE", Const, 0, ""},
		{"F_RDAHEAD", Const, 0, ""},
		{"F_RDLCK", Const, 0, ""},
		{"F_READAHEAD", Const, 0, ""},
		{"F_READBOOTSTRAP", Const, 0, ""},
		{"F_SETBACKINGSTORE", Const, 0, ""},
		{"F_SETFD", Const, 0, ""},
		{"F_SETFL", Const, 0, ""},
		{"F_SETLEASE", Const, 0, ""},
		{"F_SETLK", Const, 0, ""},
		{"F_SETLK64", Const, 0, ""},
		{"F_SETLKW", Const, 0, ""},
		{"F_SETLKW64", Const, 0, ""},
		{"F_SETLKWTIMEOUT", Const, 16, ""},
		{"F_SETLK_REMOTE", Const, 0, ""},
		{"F_SETNOSIGPIPE", Const, 0, ""},
		{"F_SETOWN", Const, 0, ""},
		{"F_SETOWN_EX", Const, 0, ""},
		{"F_SETPIPE_SZ", Const, 0, ""},
		{"F_SETPROTECTIONCLASS", Const, 0, ""},
		{"F_SETSIG", Const, 0, ""},
		{"F_SETSIZE", Const, 0, ""},
		{"F_SHLCK", Const, 0, ""},
		{"F_SINGLE_WRITER", Const, 16, ""},
		{"F_TEST", Const, 0, ""},
		{"F_THAW_FS", Const, 0, ""},
		{"F_TLOCK", Const, 0, ""},
		{"F_TRANSCODEKEY", Const, 16, ""},
		{"F_ULOCK", Const, 0, ""},
		{"F_UNLCK", Const, 0, ""},
		{"F_UNLCKSYS", Const, 0, ""},
		{"F_VOLPOSMODE", Const, 0, ""},
		{"F_WRITEBOOTSTRAP", Const, 0, ""},
		{"F_WRLCK", Const, 0, ""},
		{"Faccessat", Func, 0, "func(dirfd int, path string, mode uint32, flags int) (err error)"},
		{"Fallocate", Func, 0, "func(fd int, mode uint32, off int64, len int64) (err error)"},
		{"Fbootstraptransfer_t", Type, 0, ""},
		{"Fbootstraptransfer_t.Buffer", Field, 0, ""},
		{"Fbootstraptransfer_t.Length", Field, 0, ""},
		{"Fbootstraptransfer_t.Offset", Field, 0, ""},
		{"Fchdir", Func, 0, "func(fd int) (err error)"},
		{"Fchflags", Func, 0, ""},
		{"Fchmod", Func, 0, "func(fd int, mode uint32) (err error)"},
		{"Fchmodat", Func, 0, "func(dirfd int, path string, mode uint32, flags int) error"},
		{"Fchown", Func, 0, "func(fd int, uid int, gid int) (err error)"},
		{"Fchownat", Func, 0, "func(dirfd int, path string, uid int, gid int, flags int) (err error)"},
		{"FcntlFlock", Func, 3, "func(fd uintptr, cmd int, lk *Flock_t) error"},
		{"FdSet", Type, 0, ""},
		{"FdSet.Bits", Field, 0, ""},
		{"FdSet.X__fds_bits", Field, 0, ""},
		{"Fdatasync", Func, 0, "func(fd int) (err error)"},
		{"FileNotifyInformation", Type, 0, ""},
		{"FileNotifyInformation.Action", Field, 0, ""},
		{"FileNotifyInformation.FileName", Field, 0, ""},
		{"FileNotifyInformation.FileNameLength", Field, 0, ""},
		{"FileNotifyInformation.NextEntryOffset", Field, 0, ""},
		{"Filetime", Type, 0, ""},
		{"Filetime.HighDateTime", Field, 0, ""},
		{"Filetime.LowDateTime", Field, 0, ""},
		{"FindClose", Func, 0, ""},
		{"FindFirstFile", Func, 0, ""},
		{"FindNextFile", Func, 0, ""},
		{"Flock", Func, 0, "func(fd int, how int) (err error)"},
		{"Flock_t", Type, 0, ""},
		{"Flock_t.Len", Field, 0, ""},
		{"Flock_t.Pad_cgo_0", Field, 0, ""},
		{"Flock_t.Pad_cgo_1", Field, 3, ""},
		{"Flock_t.Pid", Field, 0, ""},
		{"Flock_t.Start", Field, 0, ""},
		{"Flock_t.Sysid", Field, 0, ""},
		{"Flock_t.Type", Field, 0, ""},
		{"Flock_t.Whence", Field, 0, ""},
		{"FlushBpf", Func, 0, ""},
		{"FlushFileBuffers", Func, 0, ""},
		{"FlushViewOfFile", Func, 0, ""},
		{"ForkExec", Func, 0, "func(argv0 string, argv []string, attr *ProcAttr) (pid int, err error)"},
		{"ForkLock", Var, 0, ""},
		{"FormatMessage", Func, 0, ""},
		{"Fpathconf", Func, 0, ""},
		{"FreeAddrInfoW", Func, 1, ""},
		{"FreeEnvironmentStrings", Func, 0, ""},
		{"FreeLibrary", Func, 0, ""},
		{"Fsid", Type, 0, ""},
		{"Fsid.Val", Field, 0, ""},
		{"Fsid.X__fsid_val", Field, 2, ""},
		{"Fsid.X__val", Field, 0, ""},
		{"Fstat", Func, 0, "func(fd int, stat *Stat_t) (err error)"},
		{"Fstatat", Func, 12, ""},
		{"Fstatfs", Func, 0, "func(fd int, buf *Statfs_t) (err error)"},
		{"Fstore_t", Type, 0, ""},
		{"Fstore_t.Bytesalloc", Field, 0, ""},
		{"Fstore_t.Flags", Field, 0, ""},
		{"Fstore_t.Length", Field, 0, ""},
		{"Fstore_t.Offset", Field, 0, ""},
		{"Fstore_t.Posmode", Field, 0, ""},
		{"Fsync", Func, 0, "func(fd int) (err error)"},
		{"Ftruncate", Func, 0, "func(fd int, length int64) (err error)"},
		{"FullPath", Func, 4, ""},
		{"Futimes", Func, 0, "func(fd int, tv []Timeval) (err error)"},
		{"Futimesat", Func, 0, "func(dirfd int, path string, tv []Timeval) (err error)"},
		{"GENERIC_ALL", Const, 0, ""},
		{"GENERIC_EXECUTE", Const, 0, ""},
		{"GENERIC_READ", Const, 0, ""},
		{"GENERIC_WRITE", Const, 0, ""},
		{"GUID", Type, 1, ""},
		{"GUID.Data1", Field, 1, ""},
		{"GUID.Data2", Field, 1, ""},
		{"GUID.Data3", Field, 1, ""},
		{"GUID.Data4", Field, 1, ""},
		{"GetAcceptExSockaddrs", Func, 0, ""},
		{"GetAdaptersInfo", Func, 0, ""},
		{"GetAddrInfoW", Func, 1, ""},
		{"GetCommandLine", Func, 0, ""},
		{"GetComputerName", Func, 0, ""},
		{"GetConsoleMode", Func, 1, ""},
		{"GetCurrentDirectory", Func, 0, ""},
		{"GetCurrentProcess", Func, 0, ""},
		{"GetEnvironmentStrings", Func, 0, ""},
		{"GetEnvironmentVariable", Func, 0, ""},
		{"GetExitCodeProcess", Func, 0, ""},
		{"GetFileAttributes", Func, 0, ""},
		{"GetFileAttributesEx", Func, 0, ""},
		{"GetFileExInfoStandard", Const, 0, ""},
		{"GetFileExMaxInfoLevel", Const, 0, ""},
		{"GetFileInformationByHandle", Func, 0, ""},
		{"GetFileType", Func, 0, ""},
		{"GetFullPathName", Func, 0, ""},
		{"GetHostByName", Func, 0, ""},
		{"GetIfEntry", Func, 0, ""},
		{"GetLastError", Func, 0, ""},
		{"GetLengthSid", Func, 0, ""},
		{"GetLongPathName", Func, 0, ""},
		{"GetProcAddress", Func, 0, ""},
		{"GetProcessTimes", Func, 0, ""},
		{"GetProtoByName", Func, 0, ""},
		{"GetQueuedCompletionStatus", Func, 0, ""},
		{"GetServByName", Func, 0, ""},
		{"GetShortPathName", Func, 0, ""},
		{"GetStartupInfo", Func, 0, ""},
		{"GetStdHandle", Func, 0, ""},
		{"GetSystemTimeAsFileTime", Func, 0, ""},
		{"GetTempPath", Func, 0, ""},
		{"GetTimeZoneInformation", Func, 0, ""},
		{"GetTokenInformation", Func, 0, ""},
		{"GetUserNameEx", Func, 0, ""},
		{"GetUserProfileDirectory", Func, 0, ""},
		{"GetVersion", Func, 0, ""},
		{"Getcwd", Func, 0, "func(buf []byte) (n int, err error)"},
		{"Getdents", Func, 0, "func(fd int, buf []byte) (n int, err error)"},
		{"Getdirentries", Func, 0, ""},
		{"Getdtablesize", Func, 0, ""},
		{"Getegid", Func, 0, "func() (egid int)"},
		{"Getenv", Func, 0, "func(key string) (value string, found bool)"},
		{"Geteuid", Func, 0, "func() (euid int)"},
		{"Getfsstat", Func, 0, ""},
		{"Getgid", Func, 0, "func() (gid int)"},
		{"Getgroups", Func, 0, "func() (gids []int, err error)"},
		{"Getpagesize", Func, 0, "func() int"},
		{"Getpeername", Func, 0, "func(fd int) (sa Sockaddr, err error)"},
		{"Getpgid", Func, 0, "func(pid int) (pgid int, err error)"},
		{"Getpgrp", Func, 0, "func() (pid int)"},
		{"Getpid", Func, 0, "func() (pid int)"},
		{"Getppid", Func, 0, "func() (ppid int)"},
		{"Getpriority", Func, 0, "func(which int, who int) (prio int, err error)"},
		{"Getrlimit", Func, 0, "func(resource int, rlim *Rlimit) (err error)"},
		{"Getrusage", Func, 0, "func(who int, rusage *Rusage) (err error)"},
		{"Getsid", Func, 0, ""},
		{"Getsockname", Func, 0, "func(fd int) (sa Sockaddr, err error)"},
		{"Getsockopt", Func, 1, ""},
		{"GetsockoptByte", Func, 0, ""},
		{"GetsockoptICMPv6Filter", Func, 2, "func(fd int, level int, opt int) (*ICMPv6Filter, error)"},
		{"GetsockoptIPMreq", Func, 0, "func(fd int, level int, opt int) (*IPMreq, error)"},
		{"GetsockoptIPMreqn", Func, 0, "func(fd int, level int, opt int) (*IPMreqn, error)"},
		{"GetsockoptIPv6MTUInfo", Func, 2, "func(fd int, level int, opt int) (*IPv6MTUInfo, error)"},
		{"GetsockoptIPv6Mreq", Func, 0, "func(fd int, level int, opt int) (*IPv6Mreq, error)"},
		{"GetsockoptInet4Addr", Func, 0, "func(fd int, level int, opt int) (value [4]byte, err error)"},
		{"GetsockoptInt", Func, 0, "func(fd int, level int, opt int) (value int, err error)"},
		{"GetsockoptUcred", Func, 1, "func(fd int, level int, opt int) (*Ucred, error)"},
		{"Gettid", Func, 0, "func() (tid int)"},
		{"Gettimeofday", Func, 0, "func(tv *Timeval) (err error)"},
		{"Getuid", Func, 0, "func() (uid int)"},
		{"Getwd", Func, 0, "func() (wd string, err error)"},
		{"Getxattr", Func, 1, "func(path string, attr string, dest []byte) (sz int, err error)"},
		{"HANDLE_FLAG_INHERIT", Const, 0, ""},
		{"HKEY_CLASSES_ROOT", Const, 0, ""},
		{"HKEY_CURRENT_CONFIG", Const, 0, ""},
		{"HKEY_CURRENT_USER", Const, 0, ""},
		{"HKEY_DYN_DATA", Const, 0, ""},
		{"HKEY_LOCAL_MACHINE", Const, 0, ""},
		{"HKEY_PERFORMANCE_DATA", Const, 0, ""},
		{"HKEY_USERS", Const, 0, ""},
		{"HUPCL", Const, 0, ""},
		{"Handle", Type, 0, ""},
		{"Hostent", Type, 0, ""},
		{"Hostent.AddrList", Field, 0, ""},
		{"Hostent.AddrType", Field, 0, ""},
		{"Hostent.Aliases", Field, 0, ""},
		{"Hostent.Length", Field, 0, ""},
		{"Hostent.Name", Field, 0, ""},
		{"ICANON", Const, 0, ""},
		{"ICMP6_FILTER", Const, 2, ""},
		{"ICMPV6_FILTER", Const, 2, ""},
		{"ICMPv6Filter", Type, 2, ""},
		{"ICMPv6Filter.Data", Field, 2, ""},
		{"ICMPv6Filter.Filt", Field, 2, ""},
		{"ICRNL", Const, 0, ""},
		{"IEXTEN", Const, 0, ""},
		{"IFAN_ARRIVAL", Const, 1, ""},
		{"IFAN_DEPARTURE", Const, 1, ""},
		{"IFA_ADDRESS", Const, 0, ""},
		{"IFA_ANYCAST", Const, 0, ""},
		{"IFA_BROADCAST", Const, 0, ""},
		{"IFA_CACHEINFO", Const, 0, ""},
		{"IFA_F_DADFAILED", Const, 0, ""},
		{"IFA_F_DEPRECATED", Const, 0, ""},
		{"IFA_F_HOMEADDRESS", Const, 0, ""},
		{"IFA_F_NODAD", Const, 0, ""},
		{"IFA_F_OPTIMISTIC", Const, 0, ""},
		{"IFA_F_PERMANENT", Const, 0, ""},
		{"IFA_F_SECONDARY", Const, 0, ""},
		{"IFA_F_TEMPORARY", Const, 0, ""},
		{"IFA_F_TENTATIVE", Const, 0, ""},
		{"IFA_LABEL", Const, 0, ""},
		{"IFA_LOCAL", Const, 0, ""},
		{"IFA_MAX", Const, 0, ""},
		{"IFA_MULTICAST", Const, 0, ""},
		{"IFA_ROUTE", Const, 1, ""},
		{"IFA_UNSPEC", Const, 0, ""},
		{"IFF_ALLMULTI", Const, 0, ""},
		{"IFF_ALTPHYS", Const, 0, ""},
		{"IFF_AUTOMEDIA", Const, 0, ""},
		{"IFF_BROADCAST", Const, 0, ""},
		{"IFF_CANTCHANGE", Const, 0, ""},
		{"IFF_CANTCONFIG", Const, 1, ""},
		{"IFF_DEBUG", Const, 0, ""},
		{"IFF_DRV_OACTIVE", Const, 0, ""},
		{"IFF_DRV_RUNNING", Const, 0, ""},
		{"IFF_DYING", Const, 0, ""},
		{"IFF_DYNAMIC", Const, 0, ""},
		{"IFF_LINK0", Const, 0, ""},
		{"IFF_LINK1", Const, 0, ""},
		{"IFF_LINK2", Const, 0, ""},
		{"IFF_LOOPBACK", Const, 0, ""},
		{"IFF_MASTER", Const, 0, ""},
		{"IFF_MONITOR", Const, 0, ""},
		{"IFF_MULTICAST", Const, 0, ""},
		{"IFF_NOARP", Const, 0, ""},
		{"IFF_NOTRAILERS", Const, 0, ""},
		{"IFF_NO_PI", Const, 0, ""},
		{"IFF_OACTIVE", Const, 0, ""},
		{"IFF_ONE_QUEUE", Const, 0, ""},
		{"IFF_POINTOPOINT", Const, 0, ""},
		{"IFF_POINTTOPOINT", Const, 0, ""},
		{"IFF_PORTSEL", Const, 0, ""},
		{"IFF_PPROMISC", Const, 0, ""},
		{"IFF_PROMISC", Const, 0, ""},
		{"IFF_RENAMING", Const, 0, ""},
		{"IFF_RUNNING", Const, 0, ""},
		{"IFF_SIMPLEX", Const, 0, ""},
		{"IFF_SLAVE", Const, 0, ""},
		{"IFF_SMART", Const, 0, ""},
		{"IFF_STATICARP", Const, 0, ""},
		{"IFF_TAP", Const, 0, ""},
		{"IFF_TUN", Const, 0, ""},
		{"IFF_TUN_EXCL", Const, 0, ""},
		{"IFF_UP", Const, 0, ""},
		{"IFF_VNET_HDR", Const, 0, ""},
		{"IFLA_ADDRESS", Const, 0, ""},
		{"IFLA_BROADCAST", Const, 0, ""},
		{"IFLA_COST", Const, 0, ""},
		{"IFLA_IFALIAS", Const, 0, ""},
		{"IFLA_IFNAME", Const, 0, ""},
		{"IFLA_LINK", Const, 0, ""},
		{"IFLA_LINKINFO", Const, 0, ""},
		{"IFLA_LINKMODE", Const, 0, ""},
		{"IFLA_MAP", Const, 0, ""},
		{"IFLA_MASTER", Const, 0, ""},
		{"IFLA_MAX", Const, 0, ""},
		{"IFLA_MTU", Const, 0, ""},
		{"IFLA_NET_NS_PID", Const, 0, ""},
		{"IFLA_OPERSTATE", Const, 0, ""},
		{"IFLA_PRIORITY", Const, 0, ""},
		{"IFLA_PROTINFO", Const, 0, ""},
		{"IFLA_QDISC", Const, 0, ""},
		{"IFLA_STATS", Const, 0, ""},
		{"IFLA_TXQLEN", Const, 0, ""},
		{"IFLA_UNSPEC", Const, 0, ""},
		{"IFLA_WEIGHT", Const, 0, ""},
		{"IFLA_WIRELESS", Const, 0, ""},
		{"IFNAMSIZ", Const, 0, ""},
		{"IFT_1822", Const, 0, ""},
		{"IFT_A12MPPSWITCH", Const, 0, ""},
		{"IFT_AAL2", Const, 0, ""},
		{"IFT_AAL5", Const, 0, ""},
		{"IFT_ADSL", Const, 0, ""},
		{"IFT_AFLANE8023", Const, 0, ""},
		{"IFT_AFLANE8025", Const, 0, ""},
		{"IFT_ARAP", Const, 0, ""},
		{"IFT_ARCNET", Const, 0, ""},
		{"IFT_ARCNETPLUS", Const, 0, ""},
		{"IFT_ASYNC", Const, 0, ""},
		{"IFT_ATM", Const, 0, ""},
		{"IFT_ATMDXI", Const, 0, ""},
		{"IFT_ATMFUNI", Const, 0, ""},
		{"IFT_ATMIMA", Const, 0, ""},
		{"IFT_ATMLOGICAL", Const, 0, ""},
		{"IFT_ATMRADIO", Const, 0, ""},
		{"IFT_ATMSUBINTERFACE", Const, 0, ""},
		{"IFT_ATMVCIENDPT", Const, 0, ""},
		{"IFT_ATMVIRTUAL", Const, 0, ""},
		{"IFT_BGPPOLICYACCOUNTING", Const, 0, ""},
		{"IFT_BLUETOOTH", Const, 1, ""},
		{"IFT_BRIDGE", Const, 0, ""},
		{"IFT_BSC", Const, 0, ""},
		{"IFT_CARP", Const, 0, ""},
		{"IFT_CCTEMUL", Const, 0, ""},
		{"IFT_CELLULAR", Const, 0, ""},
		{"IFT_CEPT", Const, 0, ""},
		{"IFT_CES", Const, 0, ""},
		{"IFT_CHANNEL", Const, 0, ""},
		{"IFT_CNR", Const, 0, ""},
		{"IFT_COFFEE", Const, 0, ""},
		{"IFT_COMPOSITELINK", Const, 0, ""},
		{"IFT_DCN", Const, 0, ""},
		{"IFT_DIGITALPOWERLINE", Const, 0, ""},
		{"IFT_DIGITALWRAPPEROVERHEADCHANNEL", Const, 0, ""},
		{"IFT_DLSW", Const, 0, ""},
		{"IFT_DOCSCABLEDOWNSTREAM", Const, 0, ""},
		{"IFT_DOCSCABLEMACLAYER", Const, 0, ""},
		{"IFT_DOCSCABLEUPSTREAM", Const, 0, ""},
		{"IFT_DOCSCABLEUPSTREAMCHANNEL", Const, 1, ""},
		{"IFT_DS0", Const, 0, ""},
		{"IFT_DS0BUNDLE", Const, 0, ""},
		{"IFT_DS1FDL", Const, 0, ""},
		{"IFT_DS3", Const, 0, ""},
		{"IFT_DTM", Const, 0, ""},
		{"IFT_DUMMY", Const, 1, ""},
		{"IFT_DVBASILN", Const, 0, ""},
		{"IFT_DVBASIOUT", Const, 0, ""},
		{"IFT_DVBRCCDOWNSTREAM", Const, 0, ""},
		{"IFT_DVBRCCMACLAYER", Const, 0, ""},
		{"IFT_DVBRCCUPSTREAM", Const, 0, ""},
		{"IFT_ECONET", Const, 1, ""},
		{"IFT_ENC", Const, 0, ""},
		{"IFT_EON", Const, 0, ""},
		{"IFT_EPLRS", Const, 0, ""},
		{"IFT_ESCON", Const, 0, ""},
		{"IFT_ETHER", Const, 0, ""},
		{"IFT_FAITH", Const, 0, ""},
		{"IFT_FAST", Const, 0, ""},
		{"IFT_FASTETHER", Const, 0, ""},
		{"IFT_FASTETHERFX", Const, 0, ""},
		{"IFT_FDDI", Const, 0, ""},
		{"IFT_FIBRECHANNEL", Const, 0, ""},
		{"IFT_FRAMERELAYINTERCONNECT", Const, 0, ""},
		{"IFT_FRAMERELAYMPI", Const, 0, ""},
		{"IFT_FRDLCIENDPT", Const, 0, ""},
		{"IFT_FRELAY", Const, 0, ""},
		{"IFT_FRELAYDCE", Const, 0, ""},
		{"IFT_FRF16MFRBUNDLE", Const, 0, ""},
		{"IFT_FRFORWARD", Const, 0, ""},
		{"IFT_G703AT2MB", Const, 0, ""},
		{"IFT_G703AT64K", Const, 0, ""},
		{"IFT_GIF", Const, 0, ""},
		{"IFT_GIGABITETHERNET", Const, 0, ""},
		{"IFT_GR303IDT", Const, 0, ""},
		{"IFT_GR303RDT", Const, 0, ""},
		{"IFT_H323GATEKEEPER", Const, 0, ""},
		{"IFT_H323PROXY", Const, 0, ""},
		{"IFT_HDH1822", Const, 0, ""},
		{"IFT_HDLC", Const, 0, ""},
		{"IFT_HDSL2", Const, 0, ""},
		{"IFT_HIPERLAN2", Const, 0, ""},
		{"IFT_HIPPI", Const, 0, ""},
		{"IFT_HIPPIINTERFACE", Const, 0, ""},
		{"IFT_HOSTPAD", Const, 0, ""},
		{"IFT_HSSI", Const, 0, ""},
		{"IFT_HY", Const, 0, ""},
		{"IFT_IBM370PARCHAN", Const, 0, ""},
		{"IFT_IDSL", Const, 0, ""},
		{"IFT_IEEE1394", Const, 0, ""},
		{"IFT_IEEE80211", Const, 0, ""},
		{"IFT_IEEE80212", Const, 0, ""},
		{"IFT_IEEE8023ADLAG", Const, 0, ""},
		{"IFT_IFGSN", Const, 0, ""},
		{"IFT_IMT", Const, 0, ""},
		{"IFT_INFINIBAND", Const, 1, ""},
		{"IFT_INTERLEAVE", Const, 0, ""},
		{"IFT_IP", Const, 0, ""},
		{"IFT_IPFORWARD", Const, 0, ""},
		{"IFT_IPOVERATM", Const, 0, ""},
		{"IFT_IPOVERCDLC", Const, 0, ""},
		{"IFT_IPOVERCLAW", Const, 0, ""},
		{"IFT_IPSWITCH", Const, 0, ""},
		{"IFT_IPXIP", Const, 0, ""},
		{"IFT_ISDN", Const, 0, ""},
		{"IFT_ISDNBASIC", Const, 0, ""},
		{"IFT_ISDNPRIMARY", Const, 0, ""},
		{"IFT_ISDNS", Const, 0, ""},
		{"IFT_ISDNU", Const, 0, ""},
		{"IFT_ISO88022LLC", Const, 0, ""},
		{"IFT_ISO88023", Const, 0, ""},
		{"IFT_ISO88024", Const, 0, ""},
		{"IFT_ISO88025", Const, 0, ""},
		{"IFT_ISO88025CRFPINT", Const, 0, ""},
		{"IFT_ISO88025DTR", Const, 0, ""},
		{"IFT_ISO88025FIBER", Const, 0, ""},
		{"IFT_ISO88026", Const, 0, ""},
		{"IFT_ISUP", Const, 0, ""},
		{"IFT_L2VLAN", Const, 0, ""},
		{"IFT_L3IPVLAN", Const, 0, ""},
		{"IFT_L3IPXVLAN", Const, 0, ""},
		{"IFT_LAPB", Const, 0, ""},
		{"IFT_LAPD", Const, 0, ""},
		{"IFT_LAPF", Const, 0, ""},
		{"IFT_LINEGROUP", Const, 1, ""},
		{"IFT_LOCALTALK", Const, 0, ""},
		{"IFT_LOOP", Const, 0, ""},
		{"IFT_MEDIAMAILOVERIP", Const, 0, ""},
		{"IFT_MFSIGLINK", Const, 0, ""},
		{"IFT_MIOX25", Const, 0, ""},
		{"IFT_MODEM", Const, 0, ""},
		{"IFT_MPC", Const, 0, ""},
		{"IFT_MPLS", Const, 0, ""},
		{"IFT_MPLSTUNNEL", Const, 0, ""},
		{"IFT_MSDSL", Const, 0, ""},
		{"IFT_MVL", Const, 0, ""},
		{"IFT_MYRINET", Const, 0, ""},
		{"IFT_NFAS", Const, 0, ""},
		{"IFT_NSIP", Const, 0, ""},
		{"IFT_OPTICALCHANNEL", Const, 0, ""},
		{"IFT_OPTICALTRANSPORT", Const, 0, ""},
		{"IFT_OTHER", Const, 0, ""},
		{"IFT_P10", Const, 0, ""},
		{"IFT_P80", Const, 0, ""},
		{"IFT_PARA", Const, 0, ""},
		{"IFT_PDP", Const, 0, ""},
		{"IFT_PFLOG", Const, 0, ""},
		{"IFT_PFLOW", Const, 1, ""},
		{"IFT_PFSYNC", Const, 0, ""},
		{"IFT_PLC", Const, 0, ""},
		{"IFT_PON155", Const, 1, ""},
		{"IFT_PON622", Const, 1, ""},
		{"IFT_POS", Const, 0, ""},
		{"IFT_PPP", Const, 0, ""},
		{"IFT_PPPMULTILINKBUNDLE", Const, 0, ""},
		{"IFT_PROPATM", Const, 1, ""},
		{"IFT_PROPBWAP2MP", Const, 0, ""},
		{"IFT_PROPCNLS", Const, 0, ""},
		{"IFT_PROPDOCSWIRELESSDOWNSTREAM", Const, 0, ""},
		{"IFT_PROPDOCSWIRELESSMACLAYER", Const, 0, ""},
		{"IFT_PROPDOCSWIRELESSUPSTREAM", Const, 0, ""},
		{"IFT_PROPMUX", Const, 0, ""},
		{"IFT_PROPVIRTUAL", Const, 0, ""},
		{"IFT_PROPWIRELESSP2P", Const, 0, ""},
		{"IFT_PTPSERIAL", Const, 0, ""},
		{"IFT_PVC", Const, 0, ""},
		{"IFT_Q2931", Const, 1, ""},
		{"IFT_QLLC", Const, 0, ""},
		{"IFT_RADIOMAC", Const, 0, ""},
		{"IFT_RADSL", Const, 0, ""},
		{"IFT_REACHDSL", Const, 0, ""},
		{"IFT_RFC1483", Const, 0, ""},
		{"IFT_RS232", Const, 0, ""},
		{"IFT_RSRB", Const, 0, ""},
		{"IFT_SDLC", Const, 0, ""},
		{"IFT_SDSL", Const, 0, ""},
		{"IFT_SHDSL", Const, 0, ""},
		{"IFT_SIP", Const, 0, ""},
		{"IFT_SIPSIG", Const, 1, ""},
		{"IFT_SIPTG", Const, 1, ""},
		{"IFT_SLIP", Const, 0, ""},
		{"IFT_SMDSDXI", Const, 0, ""},
		{"IFT_SMDSICIP", Const, 0, ""},
		{"IFT_SONET", Const, 0, ""},
		{"IFT_SONETOVERHEADCHANNEL", Const, 0, ""},
		{"IFT_SONETPATH", Const, 0, ""},
		{"IFT_SONETVT", Const, 0, ""},
		{"IFT_SRP", Const, 0, ""},
		{"IFT_SS7SIGLINK", Const, 0, ""},
		{"IFT_STACKTOSTACK", Const, 0, ""},
		{"IFT_STARLAN", Const, 0, ""},
		{"IFT_STF", Const, 0, ""},
		{"IFT_T1", Const, 0, ""},
		{"IFT_TDLC", Const, 0, ""},
		{"IFT_TELINK", Const, 1, ""},
		{"IFT_TERMPAD", Const, 0, ""},
		{"IFT_TR008", Const, 0, ""},
		{"IFT_TRANSPHDLC", Const, 0, ""},
		{"IFT_TUNNEL", Const, 0, ""},
		{"IFT_ULTRA", Const, 0, ""},
		{"IFT_USB", Const, 0, ""},
		{"IFT_V11", Const, 0, ""},
		{"IFT_V35", Const, 0, ""},
		{"IFT_V36", Const, 0, ""},
		{"IFT_V37", Const, 0, ""},
		{"IFT_VDSL", Const, 0, ""},
		{"IFT_VIRTUALIPADDRESS", Const, 0, ""},
		{"IFT_VIRTUALTG", Const, 1, ""},
		{"IFT_VOICEDID", Const, 1, ""},
		{"IFT_VOICEEM", Const, 0, ""},
		{"IFT_VOICEEMFGD", Const, 1, ""},
		{"IFT_VOICEENCAP", Const, 0, ""},
		{"IFT_VOICEFGDEANA", Const, 1, ""},
		{"IFT_VOICEFXO", Const, 0, ""},
		{"IFT_VOICEFXS", Const, 0, ""},
		{"IFT_VOICEOVERATM", Const, 0, ""},
		{"IFT_VOICEOVERCABLE", Const, 1, ""},
		{"IFT_VOICEOVERFRAMERELAY", Const, 0, ""},
		{"IFT_VOICEOVERIP", Const, 0, ""},
		{"IFT_X213", Const, 0, ""},
		{"IFT_X25", Const, 0, ""},
		{"IFT_X25DDN", Const, 0, ""},
		{"IFT_X25HUNTGROUP", Const, 0, ""},
		{"IFT_X25MLP", Const, 0, ""},
		{"IFT_X25PLE", Const, 0, ""},
		{"IFT_XETHER", Const, 0, ""},
		{"IGNBRK", Const, 0, ""},
		{"IGNCR", Const, 0, ""},
		{"IGNORE", Const, 0, ""},
		{"IGNPAR", Const, 0, ""},
		{"IMAXBEL", Const, 0, ""},
		{"INFINITE", Const, 0, ""},
		{"INLCR", Const, 0, ""},
		{"INPCK", Const, 0, ""},
		{"INVALID_FILE_ATTRIBUTES", Const, 0, ""},
		{"IN_ACCESS", Const, 0, ""},
		{"IN_ALL_EVENTS", Const, 0, ""},
		{"IN_ATTRIB", Const, 0, ""},
		{"IN_CLASSA_HOST", Const, 0, ""},
		{"IN_CLASSA_MAX", Const, 0, ""},
		{"IN_CLASSA_NET", Const, 0, ""},
		{"IN_CLASSA_NSHIFT", Const, 0, ""},
		{"IN_CLASSB_HOST", Const, 0, ""},
		{"IN_CLASSB_MAX", Const, 0, ""},
		{"IN_CLASSB_NET", Const, 0, ""},
		{"IN_CLASSB_NSHIFT", Const, 0, ""},
		{"IN_CLASSC_HOST", Const, 0, ""},
		{"IN_CLASSC_NET", Const, 0, ""},
		{"IN_CLASSC_NSHIFT", Const, 0, ""},
		{"IN_CLASSD_HOST", Const, 0, ""},
		{"IN_CLASSD_NET", Const, 0, ""},
		{"IN_CLASSD_NSHIFT", Const, 0, ""},
		{"IN_CLOEXEC", Const, 0, ""},
		{"IN_CLOSE", Const, 0, ""},
		{"IN_CLOSE_NOWRITE", Const, 0, ""},
		{"IN_CLOSE_WRITE", Const, 0, ""},
		{"IN_CREATE", Const, 0, ""},
		{"IN_DELETE", Const, 0, ""},
		{"IN_DELETE_SELF", Const, 0, ""},
		{"IN_DONT_FOLLOW", Const, 0, ""},
		{"IN_EXCL_UNLINK", Const, 0, ""},
		{"IN_IGNORED", Const, 0, ""},
		{"IN_ISDIR", Const, 0, ""},
		{"IN_LINKLOCALNETNUM", Const, 0, ""},
		{"IN_LOOPBACKNET", Const, 0, ""},
		{"IN_MASK_ADD", Const, 0, ""},
		{"IN_MODIFY", Const, 0, ""},
		{"IN_MOVE", Const, 0, ""},
		{"IN_MOVED_FROM", Const, 0, ""},
		{"IN_MOVED_TO", Const, 0, ""},
		{"IN_MOVE_SELF", Const, 0, ""},
		{"IN_NONBLOCK", Const, 0, ""},
		{"IN_ONESHOT", Const, 0, ""},
		{"IN_ONLYDIR", Const, 0, ""},
		{"IN_OPEN", Const, 0, ""},
		{"IN_Q_OVERFLOW", Const, 0, ""},
		{"IN_RFC3021_HOST", Const, 1, ""},
		{"IN_RFC3021_MASK", Const, 1, ""},
		{"IN_RFC3021_NET", Const, 1, ""},
		{"IN_RFC3021_NSHIFT", Const, 1, ""},
		{"IN_UNMOUNT", Const, 0, ""},
		{"IOC_IN", Const, 1, ""},
		{"IOC_INOUT", Const, 1, ""},
		{"IOC_OUT", Const, 1, ""},
		{"IOC_VENDOR", Const, 3, ""},
		{"IOC_WS2", Const, 1, ""},
		{"IO_REPARSE_TAG_SYMLINK", Const, 4, ""},
		{"IPMreq", Type, 0, ""},
		{"IPMreq.Interface", Field, 0, ""},
		{"IPMreq.Multiaddr", Field, 0, ""},
		{"IPMreqn", Type, 0, ""},
		{"IPMreqn.Address", Field, 0, ""},
		{"IPMreqn.Ifindex", Field, 0, ""},
		{"IPMreqn.Multiaddr", Field, 0, ""},
		{"IPPROTO_3PC", Const, 0, ""},
		{"IPPROTO_ADFS", Const, 0, ""},
		{"IPPROTO_AH", Const, 0, ""},
		{"IPPROTO_AHIP", Const, 0, ""},
		{"IPPROTO_APES", Const, 0, ""},
		{"IPPROTO_ARGUS", Const, 0, ""},
		{"IPPROTO_AX25", Const, 0, ""},
		{"IPPROTO_BHA", Const, 0, ""},
		{"IPPROTO_BLT", Const, 0, ""},
		{"IPPROTO_BRSATMON", Const, 0, ""},
		{"IPPROTO_CARP", Const, 0, ""},
		{"IPPROTO_CFTP", Const, 0, ""},
		{"IPPROTO_CHAOS", Const, 0, ""},
		{"IPPROTO_CMTP", Const, 0, ""},
		{"IPPROTO_COMP", Const, 0, ""},
		{"IPPROTO_CPHB", Const, 0, ""},
		{"IPPROTO_CPNX", Const, 0, ""},
		{"IPPROTO_DCCP", Const, 0, ""},
		{"IPPROTO_DDP", Const, 0, ""},
		{"IPPROTO_DGP", Const, 0, ""},
		{"IPPROTO_DIVERT", Const, 0, ""},
		{"IPPROTO_DIVERT_INIT", Const, 3, ""},
		{"IPPROTO_DIVERT_RESP", Const, 3, ""},
		{"IPPROTO_DONE", Const, 0, ""},
		{"IPPROTO_DSTOPTS", Const, 0, ""},
		{"IPPROTO_EGP", Const, 0, ""},
		{"IPPROTO_EMCON", Const, 0, ""},
		{"IPPROTO_ENCAP", Const, 0, ""},
		{"IPPROTO_EON", Const, 0, ""},
		{"IPPROTO_ESP", Const, 0, ""},
		{"IPPROTO_ETHERIP", Const, 0, ""},
		{"IPPROTO_FRAGMENT", Const, 0, ""},
		{"IPPROTO_GGP", Const, 0, ""},
		{"IPPROTO_GMTP", Const, 0, ""},
		{"IPPROTO_GRE", Const, 0, ""},
		{"IPPROTO_HELLO", Const, 0, ""},
		{"IPPROTO_HMP", Const, 0, ""},
		{"IPPROTO_HOPOPTS", Const, 0, ""},
		{"IPPROTO_ICMP", Const, 0, ""},
		{"IPPROTO_ICMPV6", Const, 0, ""},
		{"IPPROTO_IDP", Const, 0, ""},
		{"IPPROTO_IDPR", Const, 0, ""},
		{"IPPROTO_IDRP", Const, 0, ""},
		{"IPPROTO_IGMP", Const, 0, ""},
		{"IPPROTO_IGP", Const, 0, ""},
		{"IPPROTO_IGRP", Const, 0, ""},
		{"IPPROTO_IL", Const, 0, ""},
		{"IPPROTO_INLSP", Const, 0, ""},
		{"IPPROTO_INP", Const, 0, ""},
		{"IPPROTO_IP", Const, 0, ""},
		{"IPPROTO_IPCOMP", Const, 0, ""},
		{"IPPROTO_IPCV", Const, 0, ""},
		{"IPPROTO_IPEIP", Const, 0, ""},
		{"IPPROTO_IPIP", Const, 0, ""},
		{"IPPROTO_IPPC", Const, 0, ""},
		{"IPPROTO_IPV4", Const, 0, ""},
		{"IPPROTO_IPV6", Const, 0, ""},
		{"IPPROTO_IPV6_ICMP", Const, 1, ""},
		{"IPPROTO_IRTP", Const, 0, ""},
		{"IPPROTO_KRYPTOLAN", Const, 0, ""},
		{"IPPROTO_LARP", Const, 0, ""},
		{"IPPROTO_LEAF1", Const, 0, ""},
		{"IPPROTO_LEAF2", Const, 0, ""},
		{"IPPROTO_MAX", Const, 0, ""},
		{"IPPROTO_MAXID", Const, 0, ""},
		{"IPPROTO_MEAS", Const, 0, ""},
		{"IPPROTO_MH", Const, 1, ""},
		{"IPPROTO_MHRP", Const, 0, ""},
		{"IPPROTO_MICP", Const, 0, ""},
		{"IPPROTO_MOBILE", Const, 0, ""},
		{"IPPROTO_MPLS", Const, 1, ""},
		{"IPPROTO_MTP", Const, 0, ""},
		{"IPPROTO_MUX", Const, 0, ""},
		{"IPPROTO_ND", Const, 0, ""},
		{"IPPROTO_NHRP", Const, 0, ""},
		{"IPPROTO_NONE", Const, 0, ""},
		{"IPPROTO_NSP", Const, 0, ""},
		{"IPPROTO_NVPII", Const, 0, ""},
		{"IPPROTO_OLD_DIVERT", Const, 0, ""},
		{"IPPROTO_OSPFIGP", Const, 0, ""},
		{"IPPROTO_PFSYNC", Const, 0, ""},
		{"IPPROTO_PGM", Const, 0, ""},
		{"IPPROTO_PIGP", Const, 0, ""},
		{"IPPROTO_PIM", Const, 0, ""},
		{"IPPROTO_PRM", Const, 0, ""},
		{"IPPROTO_PUP", Const, 0, ""},
		{"IPPROTO_PVP", Const, 0, ""},
		{"IPPROTO_RAW", Const, 0, ""},
		{"IPPROTO_RCCMON", Const, 0, ""},
		{"IPPROTO_RDP", Const, 0, ""},
		{"IPPROTO_ROUTING", Const, 0, ""},
		{"IPPROTO_RSVP", Const, 0, ""},
		{"IPPROTO_RVD", Const, 0, ""},
		{"IPPROTO_SATEXPAK", Const, 0, ""},
		{"IPPROTO_SATMON", Const, 0, ""},
		{"IPPROTO_SCCSP", Const, 0, ""},
		{"IPPROTO_SCTP", Const, 0, ""},
		{"IPPROTO_SDRP", Const, 0, ""},
		{"IPPROTO_SEND", Const, 1, ""},
		{"IPPROTO_SEP", Const, 0, ""},
		{"IPPROTO_SKIP", Const, 0, ""},
		{"IPPROTO_SPACER", Const, 0, ""},
		{"IPPROTO_SRPC", Const, 0, ""},
		{"IPPROTO_ST", Const, 0, ""},
		{"IPPROTO_SVMTP", Const, 0, ""},
		{"IPPROTO_SWIPE", Const, 0, ""},
		{"IPPROTO_TCF", Const, 0, ""},
		{"IPPROTO_TCP", Const, 0, ""},
		{"IPPROTO_TLSP", Const, 0, ""},
		{"IPPROTO_TP", Const, 0, ""},
		{"IPPROTO_TPXX", Const, 0, ""},
		{"IPPROTO_TRUNK1", Const, 0, ""},
		{"IPPROTO_TRUNK2", Const, 0, ""},
		{"IPPROTO_TTP", Const, 0, ""},
		{"IPPROTO_UDP", Const, 0, ""},
		{"IPPROTO_UDPLITE", Const, 0, ""},
		{"IPPROTO_VINES", Const, 0, ""},
		{"IPPROTO_VISA", Const, 0, ""},
		{"IPPROTO_VMTP", Const, 0, ""},
		{"IPPROTO_VRRP", Const, 1, ""},
		{"IPPROTO_WBEXPAK", Const, 0, ""},
		{"IPPROTO_WBMON", Const, 0, ""},
		{"IPPROTO_WSN", Const, 0, ""},
		{"IPPROTO_XNET", Const, 0, ""},
		{"IPPROTO_XTP", Const, 0, ""},
		{"IPV6_2292DSTOPTS", Const, 0, ""},
		{"IPV6_2292HOPLIMIT", Const, 0, ""},
		{"IPV6_2292HOPOPTS", Const, 0, ""},
		{"IPV6_2292NEXTHOP", Const, 0, ""},
		{"IPV6_2292PKTINFO", Const, 0, ""},
		{"IPV6_2292PKTOPTIONS", Const, 0, ""},
		{"IPV6_2292RTHDR", Const, 0, ""},
		{"IPV6_ADDRFORM", Const, 0, ""},
		{"IPV6_ADD_MEMBERSHIP", Const, 0, ""},
		{"IPV6_AUTHHDR", Const, 0, ""},
		{"IPV6_AUTH_LEVEL", Const, 1, ""},
		{"IPV6_AUTOFLOWLABEL", Const, 0, ""},
		{"IPV6_BINDANY", Const, 0, ""},
		{"IPV6_BINDV6ONLY", Const, 0, ""},
		{"IPV6_BOUND_IF", Const, 0, ""},
		{"IPV6_CHECKSUM", Const, 0, ""},
		{"IPV6_DEFAULT_MULTICAST_HOPS", Const, 0, ""},
		{"IPV6_DEFAULT_MULTICAST_LOOP", Const, 0, ""},
		{"IPV6_DEFHLIM", Const, 0, ""},
		{"IPV6_DONTFRAG", Const, 0, ""},
		{"IPV6_DROP_MEMBERSHIP", Const, 0, ""},
		{"IPV6_DSTOPTS", Const, 0, ""},
		{"IPV6_ESP_NETWORK_LEVEL", Const, 1, ""},
		{"IPV6_ESP_TRANS_LEVEL", Const, 1, ""},
		{"IPV6_FAITH", Const, 0, ""},
		{"IPV6_FLOWINFO_MASK", Const, 0, ""},
		{"IPV6_FLOWLABEL_MASK", Const, 0, ""},
		{"IPV6_FRAGTTL", Const, 0, ""},
		{"IPV6_FW_ADD", Const, 0, ""},
		{"IPV6_FW_DEL", Const, 0, ""},
		{"IPV6_FW_FLUSH", Const, 0, ""},
		{"IPV6_FW_GET", Const, 0, ""},
		{"IPV6_FW_ZERO", Const, 0, ""},
		{"IPV6_HLIMDEC", Const, 0, ""},
		{"IPV6_HOPLIMIT", Const, 0, ""},
		{"IPV6_HOPOPTS", Const, 0, ""},
		{"IPV6_IPCOMP_LEVEL", Const, 1, ""},
		{"IPV6_IPSEC_POLICY", Const, 0, ""},
		{"IPV6_JOIN_ANYCAST", Const, 0, ""},
		{"IPV6_JOIN_GROUP", Const, 0, ""},
		{"IPV6_LEAVE_ANYCAST", Const, 0, ""},
		{"IPV6_LEAVE_GROUP", Const, 0, ""},
		{"IPV6_MAXHLIM", Const, 0, ""},
		{"IPV6_MAXOPTHDR", Const, 0, ""},
		{"IPV6_MAXPACKET", Const, 0, ""},
		{"IPV6_MAX_GROUP_SRC_FILTER", Const, 0, ""},
		{"IPV6_MAX_MEMBERSHIPS", Const, 0, ""},
		{"IPV6_MAX_SOCK_SRC_FILTER", Const, 0, ""},
		{"IPV6_MIN_MEMBERSHIPS", Const, 0, ""},
		{"IPV6_MMTU", Const, 0, ""},
		{"IPV6_MSFILTER", Const, 0, ""},
		{"IPV6_MTU", Const, 0, ""},
		{"IPV6_MTU_DISCOVER", Const, 0, ""},
		{"IPV6_MULTICAST_HOPS", Const, 0, ""},
		{"IPV6_MULTICAST_IF", Const, 0, ""},
		{"IPV6_MULTICAST_LOOP", Const, 0, ""},
		{"IPV6_NEXTHOP", Const, 0, ""},
		{"IPV6_OPTIONS", Const, 1, ""},
		{"IPV6_PATHMTU", Const, 0, ""},
		{"IPV6_PIPEX", Const, 1, ""},
		{"IPV6_PKTINFO", Const, 0, ""},
		{"IPV6_PMTUDISC_DO", Const, 0, ""},
		{"IPV6_PMTUDISC_DONT", Const, 0, ""},
		{"IPV6_PMTUDISC_PROBE", Const, 0, ""},
		{"IPV6_PMTUDISC_WANT", Const, 0, ""},
		{"IPV6_PORTRANGE", Const, 0, ""},
		{"IPV6_PORTRANGE_DEFAULT", Const, 0, ""},
		{"IPV6_PORTRANGE_HIGH", Const, 0, ""},
		{"IPV6_PORTRANGE_LOW", Const, 0, ""},
		{"IPV6_PREFER_TEMPADDR", Const, 0, ""},
		{"IPV6_RECVDSTOPTS", Const, 0, ""},
		{"IPV6_RECVDSTPORT", Const, 3, ""},
		{"IPV6_RECVERR", Const, 0, ""},
		{"IPV6_RECVHOPLIMIT", Const, 0, ""},
		{"IPV6_RECVHOPOPTS", Const, 0, ""},
		{"IPV6_RECVPATHMTU", Const, 0, ""},
		{"IPV6_RECVPKTINFO", Const, 0, ""},
		{"IPV6_RECVRTHDR", Const, 0, ""},
		{"IPV6_RECVTCLASS", Const, 0, ""},
		{"IPV6_ROUTER_ALERT", Const, 0, ""},
		{"IPV6_RTABLE", Const, 1, ""},
		{"IPV6_RTHDR", Const, 0, ""},
		{"IPV6_RTHDRDSTOPTS", Const, 0, ""},
		{"IPV6_RTHDR_LOOSE", Const, 0, ""},
		{"IPV6_RTHDR_STRICT", Const, 0, ""},
		{"IPV6_RTHDR_TYPE_0", Const, 0, ""},
		{"IPV6_RXDSTOPTS", Const, 0, ""},
		{"IPV6_RXHOPOPTS", Const, 0, ""},
		{"IPV6_SOCKOPT_RESERVED1", Const, 0, ""},
		{"IPV6_TCLASS", Const, 0, ""},
		{"IPV6_UNICAST_HOPS", Const, 0, ""},
		{"IPV6_USE_MIN_MTU", Const, 0, ""},
		{"IPV6_V6ONLY", Const, 0, ""},
		{"IPV6_VERSION", Const, 0, ""},
		{"IPV6_VERSION_MASK", Const, 0, ""},
		{"IPV6_XFRM_POLICY", Const, 0, ""},
		{"IP_ADD_MEMBERSHIP", Const, 0, ""},
		{"IP_ADD_SOURCE_MEMBERSHIP", Const, 0, ""},
		{"IP_AUTH_LEVEL", Const, 1, ""},
		{"IP_BINDANY", Const, 0, ""},
		{"IP_BLOCK_SOURCE", Const, 0, ""},
		{"IP_BOUND_IF", Const, 0, ""},
		{"IP_DEFAULT_MULTICAST_LOOP", Const, 0, ""},
		{"IP_DEFAULT_MULTICAST_TTL", Const, 0, ""},
		{"IP_DF", Const, 0, ""},
		{"IP_DIVERTFL", Const, 3, ""},
		{"IP_DONTFRAG", Const, 0, ""},
		{"IP_DROP_MEMBERSHIP", Const, 0, ""},
		{"IP_DROP_SOURCE_MEMBERSHIP", Const, 0, ""},
		{"IP_DUMMYNET3", Const, 0, ""},
		{"IP_DUMMYNET_CONFIGURE", Const, 0, ""},
		{"IP_DUMMYNET_DEL", Const, 0, ""},
		{"IP_DUMMYNET_FLUSH", Const, 0, ""},
		{"IP_DUMMYNET_GET", Const, 0, ""},
		{"IP_EF", Const, 1, ""},
		{"IP_ERRORMTU", Const, 1, ""},
		{"IP_ESP_NETWORK_LEVEL", Const, 1, ""},
		{"IP_ESP_TRANS_LEVEL", Const, 1, ""},
		{"IP_FAITH", Const, 0, ""},
		{"IP_FREEBIND", Const, 0, ""},
		{"IP_FW3", Const, 0, ""},
		{"IP_FW_ADD", Const, 0, ""},
		{"IP_FW_DEL", Const, 0, ""},
		{"IP_FW_FLUSH", Const, 0, ""},
		{"IP_FW_GET", Const, 0, ""},
		{"IP_FW_NAT_CFG", Const, 0, ""},
		{"IP_FW_NAT_DEL", Const, 0, ""},
		{"IP_FW_NAT_GET_CONFIG", Const, 0, ""},
		{"IP_FW_NAT_GET_LOG", Const, 0, ""},
		{"IP_FW_RESETLOG", Const, 0, ""},
		{"IP_FW_TABLE_ADD", Const, 0, ""},
		{"IP_FW_TABLE_DEL", Const, 0, ""},
		{"IP_FW_TABLE_FLUSH", Const, 0, ""},
		{"IP_FW_TABLE_GETSIZE", Const, 0, ""},
		{"IP_FW_TABLE_LIST", Const, 0, ""},
		{"IP_FW_ZERO", Const, 0, ""},
		{"IP_HDRINCL", Const, 0, ""},
		{"IP_IPCOMP_LEVEL", Const, 1, ""},
		{"IP_IPSECFLOWINFO", Const, 1, ""},
		{"IP_IPSEC_LOCAL_AUTH", Const, 1, ""},
		{"IP_IPSEC_LOCAL_CRED", Const, 1, ""},
		{"IP_IPSEC_LOCAL_ID", Const, 1, ""},
		{"IP_IPSEC_POLICY", Const, 0, ""},
		{"IP_IPSEC_REMOTE_AUTH", Const, 1, ""},
		{"IP_IPSEC_REMOTE_CRED", Const, 1, ""},
		{"IP_IPSEC_REMOTE_ID", Const, 1, ""},
		{"IP_MAXPACKET", Const, 0, ""},
		{"IP_MAX_GROUP_SRC_FILTER", Const, 0, ""},
		{"IP_MAX_MEMBERSHIPS", Const, 0, ""},
		{"IP_MAX_SOCK_MUTE_FILTER", Const, 0, ""},
		{"IP_MAX_SOCK_SRC_FILTER", Const, 0, ""},
		{"IP_MAX_SOURCE_FILTER", Const, 0, ""},
		{"IP_MF", Const, 0, ""},
		{"IP_MINFRAGSIZE", Const, 1, ""},
		{"IP_MINTTL", Const, 0, ""},
		{"IP_MIN_MEMBERSHIPS", Const, 0, ""},
		{"IP_MSFILTER", Const, 0, ""},
		{"IP_MSS", Const, 0, ""},
		{"IP_MTU", Const, 0, ""},
		{"IP_MTU_DISCOVER", Const, 0, ""},
		{"IP_MULTICAST_IF", Const, 0, ""},
		{"IP_MULTICAST_IFINDEX", Const, 0, ""},
		{"IP_MULTICAST_LOOP", Const, 0, ""},
		{"IP_MULTICAST_TTL", Const, 0, ""},
		{"IP_MULTICAST_VIF", Const, 0, ""},
		{"IP_NAT__XXX", Const, 0, ""},
		{"IP_OFFMASK", Const, 0, ""},
		{"IP_OLD_FW_ADD", Const, 0, ""},
		{"IP_OLD_FW_DEL", Const, 0, ""},
		{"IP_OLD_FW_FLUSH", Const, 0, ""},
		{"IP_OLD_FW_GET", Const, 0, ""},
		{"IP_OLD_FW_RESETLOG", Const, 0, ""},
		{"IP_OLD_FW_ZERO", Const, 0, ""},
		{"IP_ONESBCAST", Const, 0, ""},
		{"IP_OPTIONS", Const, 0, ""},
		{"IP_ORIGDSTADDR", Const, 0, ""},
		{"IP_PASSSEC", Const, 0, ""},
		{"IP_PIPEX", Const, 1, ""},
		{"IP_PKTINFO", Const, 0, ""},
		{"IP_PKTOPTIONS", Const, 0, ""},
		{"IP_PMTUDISC", Const, 0, ""},
		{"IP_PMTUDISC_DO", Const, 0, ""},
		{"IP_PMTUDISC_DONT", Const, 0, ""},
		{"IP_PMTUDISC_PROBE", Const, 0, ""},
		{"IP_PMTUDISC_WANT", Const, 0, ""},
		{"IP_PORTRANGE", Const, 0, ""},
		{"IP_PORTRANGE_DEFAULT", Const, 0, ""},
		{"IP_PORTRANGE_HIGH", Const, 0, ""},
		{"IP_PORTRANGE_LOW", Const, 0, ""},
		{"IP_RECVDSTADDR", Const, 0, ""},
		{"IP_RECVDSTPORT", Const, 1, ""},
		{"IP_RECVERR", Const, 0, ""},
		{"IP_RECVIF", Const, 0, ""},
		{"IP_RECVOPTS", Const, 0, ""},
		{"IP_RECVORIGDSTADDR", Const, 0, ""},
		{"IP_RECVPKTINFO", Const, 0, ""},
		{"IP_RECVRETOPTS", Const, 0, ""},
		{"IP_RECVRTABLE", Const, 1, ""},
		{"IP_RECVTOS", Const, 0, ""},
		{"IP_RECVTTL", Const, 0, ""},
		{"IP_RETOPTS", Const, 0, ""},
		{"IP_RF", Const, 0, ""},
		{"IP_ROUTER_ALERT", Const, 0, ""},
		{"IP_RSVP_OFF", Const, 0, ""},
		{"IP_RSVP_ON", Const, 0, ""},
		{"IP_RSVP_VIF_OFF", Const, 0, ""},
		{"IP_RSVP_VIF_ON", Const, 0, ""},
		{"IP_RTABLE", Const, 1, ""},
		{"IP_SENDSRCADDR", Const, 0, ""},
		{"IP_STRIPHDR", Const, 0, ""},
		{"IP_TOS", Const, 0, ""},
		{"IP_TRAFFIC_MGT_BACKGROUND", Const, 0, ""},
		{"IP_TRANSPARENT", Const, 0, ""},
		{"IP_TTL", Const, 0, ""},
		{"IP_UNBLOCK_SOURCE", Const, 0, ""},
		{"IP_XFRM_POLICY", Const, 0, ""},
		{"IPv6MTUInfo", Type, 2, ""},
		{"IPv6MTUInfo.Addr", Field, 2, ""},
		{"IPv6MTUInfo.Mtu", Field, 2, ""},
		{"IPv6Mreq", Type, 0, ""},
		{"IPv6Mreq.Interface", Field, 0, ""},
		{"IPv6Mreq.Multiaddr", Field, 0, ""},
		{"ISIG", Const, 0, ""},
		{"ISTRIP", Const, 0, ""},
		{"IUCLC", Const, 0, ""},
		{"IUTF8", Const, 0, ""},
		{"IXANY", Const, 0, ""},
		{"IXOFF", Const, 0, ""},
		{"IXON", Const, 0, ""},
		{"IfAddrmsg", Type, 0, ""},
		{"IfAddrmsg.Family", Field, 0, ""},
		{"IfAddrmsg.Flags", Field, 0, ""},
		{"IfAddrmsg.Index", Field, 0, ""},
		{"IfAddrmsg.Prefixlen", Field, 0, ""},
		{"IfAddrmsg.Scope", Field, 0, ""},
		{"IfAnnounceMsghdr", Type, 1, ""},
		{"IfAnnounceMsghdr.Hdrlen", Field, 2, ""},
		{"IfAnnounceMsghdr.Index", Field, 1, ""},
		{"IfAnnounceMsghdr.Msglen", Field, 1, ""},
		{"IfAnnounceMsghdr.Name", Field, 1, ""},
		{"IfAnnounceMsghdr.Type", Field, 1, ""},
		{"IfAnnounceMsghdr.Version", Field, 1, ""},
		{"IfAnnounceMsghdr.What", Field, 1, ""},
		{"IfData", Type, 0, ""},
		{"IfData.Addrlen", Field, 0, ""},
		{"IfData.Baudrate", Field, 0, ""},
		{"IfData.Capabilities", Field, 2, ""},
		{"IfData.Collisions", Field, 0, ""},
		{"IfData.Datalen", Field, 0, ""},
		{"IfData.Epoch", Field, 0, ""},
		{"IfData.Hdrlen", Field, 0, ""},
		{"IfData.Hwassist", Field, 0, ""},
		{"IfData.Ibytes", Field, 0, ""},
		{"IfData.Ierrors", Field, 0, ""},
		{"IfData.Imcasts", Field, 0, ""},
		{"IfData.Ipackets", Field, 0, ""},
		{"IfData.Iqdrops", Field, 0, ""},
		{"IfData.Lastchange", Field, 0, ""},
		{"IfData.Link_state", Field, 0, ""},
		{"IfData.Mclpool", Field, 2, ""},
		{"IfData.Metric", Field, 0, ""},
		{"IfData.Mtu", Field, 0, ""},
		{"IfData.Noproto", Field, 0, ""},
		{"IfData.Obytes", Field, 0, ""},
		{"IfData.Oerrors", Field, 0, ""},
		{"IfData.Omcasts", Field, 0, ""},
		{"IfData.Opackets", Field, 0, ""},
		{"IfData.Pad", Field, 2, ""},
		{"IfData.Pad_cgo_0", Field, 2, ""},
		{"IfData.Pad_cgo_1", Field, 2, ""},
		{"IfData.Physical", Field, 0, ""},
		{"IfData.Recvquota", Field, 0, ""},
		{"IfData.Recvtiming", Field, 0, ""},
		{"IfData.Reserved1", Field, 0, ""},
		{"IfData.Reserved2", Field, 0, ""},
		{"IfData.Spare_char1", Field, 0, ""},
		{"IfData.Spare_char2", Field, 0, ""},
		{"IfData.Type", Field, 0, ""},
		{"IfData.Typelen", Field, 0, ""},
		{"IfData.Unused1", Field, 0, ""},
		{"IfData.Unused2", Field, 0, ""},
		{"IfData.Xmitquota", Field, 0, ""},
		{"IfData.Xmittiming", Field, 0, ""},
		{"IfInfomsg", Type, 0, ""},
		{"IfInfomsg.Change", Field, 0, ""},
		{"IfInfomsg.Family", Field, 0, ""},
		{"IfInfomsg.Flags", Field, 0, ""},
		{"IfInfomsg.Index", Field, 0, ""},
		{"IfInfomsg.Type", Field, 0, ""},
		{"IfInfomsg.X__ifi_pad", Field, 0, ""},
		{"IfMsghdr", Type, 0, ""},
		{"IfMsghdr.Addrs", Field, 0, ""},
		{"IfMsghdr.Data", Field, 0, ""},
		{"IfMsghdr.Flags", Field, 0, ""},
		{"IfMsghdr.Hdrlen", Field, 2, ""},
		{"IfMsghdr.Index", Field, 0, ""},
		{"IfMsghdr.Msglen", Field, 0, ""},
		{"IfMsghdr.Pad1", Field, 2, ""},
		{"IfMsghdr.Pad2", Field, 2, ""},
		{"IfMsghdr.Pad_cgo_0", Field, 0, ""},
		{"IfMsghdr.Pad_cgo_1", Field, 2, ""},
		{"IfMsghdr.Tableid", Field, 2, ""},
		{"IfMsghdr.Type", Field, 0, ""},
		{"IfMsghdr.Version", Field, 0, ""},
		{"IfMsghdr.Xflags", Field, 2, ""},
		{"IfaMsghdr", Type, 0, ""},
		{"IfaMsghdr.Addrs", Field, 0, ""},
		{"IfaMsghdr.Flags", Field, 0, ""},
		{"IfaMsghdr.Hdrlen", Field, 2, ""},
		{"IfaMsghdr.Index", Field, 0, ""},
		{"IfaMsghdr.Metric", Field, 0, ""},
		{"IfaMsghdr.Msglen", Field, 0, ""},
		{"IfaMsghdr.Pad1", Field, 2, ""},
		{"IfaMsghdr.Pad2", Field, 2, ""},
		{"IfaMsghdr.Pad_cgo_0", Field, 0, ""},
		{"IfaMsghdr.Tableid", Field, 2, ""},
		{"IfaMsghdr.Type", Field, 0, ""},
		{"IfaMsghdr.Version", Field, 0, ""},
		{"IfmaMsghdr", Type, 0, ""},
		{"IfmaMsghdr.Addrs", Field, 0, ""},
		{"IfmaMsghdr.Flags", Field, 0, ""},
		{"IfmaMsghdr.Index", Field, 0, ""},
		{"IfmaMsghdr.Msglen", Field, 0, ""},
		{"IfmaMsghdr.Pad_cgo_0", Field, 0, ""},
		{"IfmaMsghdr.Type", Field, 0, ""},
		{"IfmaMsghdr.Version", Field, 0, ""},
		{"IfmaMsghdr2", Type, 0, ""},
		{"IfmaMsghdr2.Addrs", Field, 0, ""},
		{"IfmaMsghdr2.Flags", Field, 0, ""},
		{"IfmaMsghdr2.Index", Field, 0, ""},
		{"IfmaMsghdr2.Msglen", Field, 0, ""},
		{"IfmaMsghdr2.Pad_cgo_0", Field, 0, ""},
		{"IfmaMsghdr2.Refcount", Field, 0, ""},
		{"IfmaMsghdr2.Type", Field, 0, ""},
		{"IfmaMsghdr2.Version", Field, 0, ""},
		{"ImplementsGetwd", Const, 0, ""},
		{"Inet4Pktinfo", Type, 0, ""},
		{"Inet4Pktinfo.Addr", Field, 0, ""},
		{"Inet4Pktinfo.Ifindex", Field, 0, ""},
		{"Inet4Pktinfo.Spec_dst", Field, 0, ""},
		{"Inet6Pktinfo", Type, 0, ""},
		{"Inet6Pktinfo.Addr", Field, 0, ""},
		{"Inet6Pktinfo.Ifindex", Field, 0, ""},
		{"InotifyAddWatch", Func, 0, "func(fd int, pathname string, mask uint32) (watchdesc int, err error)"},
		{"InotifyEvent", Type, 0, ""},
		{"InotifyEvent.Cookie", Field, 0, ""},
		{"InotifyEvent.Len", Field, 0, ""},
		{"InotifyEvent.Mask", Field, 0, ""},
		{"InotifyEvent.Name", Field, 0, ""},
		{"InotifyEvent.Wd", Field, 0, ""},
		{"InotifyInit", Func, 0, "func() (fd int, err error)"},
		{"InotifyInit1", Func, 0, "func(flags int) (fd int, err error)"},
		{"InotifyRmWatch", Func, 0, "func(fd int, watchdesc uint32) (success int, err error)"},
		{"InterfaceAddrMessage", Type, 0, ""},
		{"InterfaceAddrMessage.Data", Field, 0, ""},
		{"InterfaceAddrMessage.Header", Field, 0, ""},
		{"InterfaceAnnounceMessage", Type, 1, ""},
		{"InterfaceAnnounceMessage.Header", Field, 1, ""},
		{"InterfaceInfo", Type, 0, ""},
		{"InterfaceInfo.Address", Field, 0, ""},
		{"InterfaceInfo.BroadcastAddress", Field, 0, ""},
		{"InterfaceInfo.Flags", Field, 0, ""},
		{"InterfaceInfo.Netmask", Field, 0, ""},
		{"InterfaceMessage", Type, 0, ""},
		{"InterfaceMessage.Data", Field, 0, ""},
		{"InterfaceMessage.Header", Field, 0, ""},
		{"InterfaceMulticastAddrMessage", Type, 0, ""},
		{"InterfaceMulticastAddrMessage.Data", Field, 0, ""},
		{"InterfaceMulticastAddrMessage.Header", Field, 0, ""},
		{"InvalidHandle", Const, 0, ""},
		{"Ioperm", Func, 0, "func(from int, num int, on int) (err error)"},
		{"Iopl", Func, 0, "func(level int) (err error)"},
		{"Iovec", Type, 0, ""},
		{"Iovec.Base", Field, 0, ""},
		{"Iovec.Len", Field, 0, ""},
		{"IpAdapterInfo", Type, 0, ""},
		{"IpAdapterInfo.AdapterName", Field, 0, ""},
		{"IpAdapterInfo.Address", Field, 0, ""},
		{"IpAdapterInfo.AddressLength", Field, 0, ""},
		{"IpAdapterInfo.ComboIndex", Field, 0, ""},
		{"IpAdapterInfo.CurrentIpAddress", Field, 0, ""},
		{"IpAdapterInfo.Description", Field, 0, ""},
		{"IpAdapterInfo.DhcpEnabled", Field, 0, ""},
		{"IpAdapterInfo.DhcpServer", Field, 0, ""},
		{"IpAdapterInfo.GatewayList", Field, 0, ""},
		{"IpAdapterInfo.HaveWins", Field, 0, ""},
		{"IpAdapterInfo.Index", Field, 0, ""},
		{"IpAdapterInfo.IpAddressList", Field, 0, ""},
		{"IpAdapterInfo.LeaseExpires", Field, 0, ""},
		{"IpAdapterInfo.LeaseObtained", Field, 0, ""},
		{"IpAdapterInfo.Next", Field, 0, ""},
		{"IpAdapterInfo.PrimaryWinsServer", Field, 0, ""},
		{"IpAdapterInfo.SecondaryWinsServer", Field, 0, ""},
		{"IpAdapterInfo.Type", Field, 0, ""},
		{"IpAddrString", Type, 0, ""},
		{"IpAddrString.Context", Field, 0, ""},
		{"IpAddrString.IpAddress", Field, 0, ""},
		{"IpAddrString.IpMask", Field, 0, ""},
		{"IpAddrString.Next", Field, 0, ""},
		{"IpAddressString", Type, 0, ""},
		{"IpAddressString.String", Field, 0, ""},
		{"IpMaskString", Type, 0, ""},
		{"IpMaskString.String", Field, 2, ""},
		{"Issetugid", Func, 0, ""},
		{"KEY_ALL_ACCESS", Const, 0, ""},
		{"KEY_CREATE_LINK", Const, 0, ""},
		{"KEY_CREATE_SUB_KEY", Const, 0, ""},
		{"KEY_ENUMERATE_SUB_KEYS", Const, 0, ""},
		{"KEY_EXECUTE", Const, 0, ""},
		{"KEY_NOTIFY", Const, 0, ""},
		{"KEY_QUERY_VALUE", Const, 0, ""},
		{"KEY_READ", Const, 0, ""},
		{"KEY_SET_VALUE", Const, 0, ""},
		{"KEY_WOW64_32KEY", Const, 0, ""},
		{"KEY_WOW64_64KEY", Const, 0, ""},
		{"KEY_WRITE", Const, 0, ""},
		{"Kevent", Func, 0, ""},
		{"Kevent_t", Type, 0, ""},
		{"Kevent_t.Data", Field, 0, ""},
		{"Kevent_t.Fflags", Field, 0, ""},
		{"Kevent_t.Filter", Field, 0, ""},
		{"Kevent_t.Flags", Field, 0, ""},
		{"Kevent_t.Ident", Field, 0, ""},
		{"Kevent_t.Pad_cgo_0", Field, 2, ""},
		{"Kevent_t.Udata", Field, 0, ""},
		{"Kill", Func, 0, "func(pid int, sig Signal) (err error)"},
		{"Klogctl", Func, 0, "func(typ int, buf []byte) (n int, err error)"},
		{"Kqueue", Func, 0, ""},
		{"LANG_ENGLISH", Const, 0, ""},
		{"LAYERED_PROTOCOL", Const, 2, ""},
		{"LCNT_OVERLOAD_FLUSH", Const, 1, ""},
		{"LINUX_REBOOT_CMD_CAD_OFF", Const, 0, ""},
		{"LINUX_REBOOT_CMD_CAD_ON", Const, 0, ""},
		{"LINUX_REBOOT_CMD_HALT", Const, 0, ""},
		{"LINUX_REBOOT_CMD_KEXEC", Const, 0, ""},
		{"LINUX_REBOOT_CMD_POWER_OFF", Const, 0, ""},
		{"LINUX_REBOOT_CMD_RESTART", Const, 0, ""},
		{"LINUX_REBOOT_CMD_RESTART2", Const, 0, ""},
		{"LINUX_REBOOT_CMD_SW_SUSPEND", Const, 0, ""},
		{"LINUX_REBOOT_MAGIC1", Const, 0, ""},
		{"LINUX_REBOOT_MAGIC2", Const, 0, ""},
		{"LOCK_EX", Const, 0, ""},
		{"LOCK_NB", Const, 0, ""},
		{"LOCK_SH", Const, 0, ""},
		{"LOCK_UN", Const, 0, ""},
		{"LazyDLL", Type, 0, ""},
		{"LazyDLL.Name", Field, 0, ""},
		{"LazyProc", Type, 0, ""},
		{"LazyProc.Name", Field, 0, ""},
		{"Lchown", Func, 0, "func(path string, uid int, gid int) (err error)"},
		{"Linger", Type, 0, ""},
		{"Linger.Linger", Field, 0, ""},
		{"Linger.Onoff", Field, 0, ""},
		{"Link", Func, 0, "func(oldpath string, newpath string) (err error)"},
		{"Listen", Func, 0, "func(s int, n int) (err error)"},
		{"Listxattr", Func, 1, "func(path string, dest []byte) (sz int, err error)"},
		{"LoadCancelIoEx", Func, 1, ""},
		{"LoadConnectEx", Func, 1, ""},
		{"LoadCreateSymbolicLink", Func, 4, ""},
		{"LoadDLL", Func, 0, ""},
		{"LoadGetAddrInfo", Func, 1, ""},
		{"LoadLibrary", Func, 0, ""},
		{"LoadSetFileCompletionNotificationModes", Func, 2, ""},
		{"LocalFree", Func, 0, ""},
		{"Log2phys_t", Type, 0, ""},
		{"Log2phys_t.Contigbytes", Field, 0, ""},
		{"Log2phys_t.Devoffset", Field, 0, ""},
		{"Log2phys_t.Flags", Field, 0, ""},
		{"LookupAccountName", Func, 0, ""},
		{"LookupAccountSid", Func, 0, ""},
		{"LookupSID", Func, 0, ""},
		{"LsfJump", Func, 0, "func(code int, k int, jt int, jf int) *SockFilter"},
		{"LsfSocket", Func, 0, "func(ifindex int, proto int) (int, error)"},
		{"LsfStmt", Func, 0, "func(code int, k int) *SockFilter"},
		{"Lstat", Func, 0, "func(path string, stat *Stat_t) (err error)"},
		{"MADV_AUTOSYNC", Const, 1, ""},
		{"MADV_CAN_REUSE", Const, 0, ""},
		{"MADV_CORE", Const, 1, ""},
		{"MADV_DOFORK", Const, 0, ""},
		{"MADV_DONTFORK", Const, 0, ""},
		{"MADV_DONTNEED", Const, 0, ""},
		{"MADV_FREE", Const, 0, ""},
		{"MADV_FREE_REUSABLE", Const, 0, ""},
		{"MADV_FREE_REUSE", Const, 0, ""},
		{"MADV_HUGEPAGE", Const, 0, ""},
		{"MADV_HWPOISON", Const, 0, ""},
		{"MADV_MERGEABLE", Const, 0, ""},
		{"MADV_NOCORE", Const, 1, ""},
		{"MADV_NOHUGEPAGE", Const, 0, ""},
		{"MADV_NORMAL", Const, 0, ""},
		{"MADV_NOSYNC", Const, 1, ""},
		{"MADV_PROTECT", Const, 1, ""},
		{"MADV_RANDOM", Const, 0, ""},
		{"MADV_REMOVE", Const, 0, ""},
		{"MADV_SEQUENTIAL", Const, 0, ""},
		{"MADV_SPACEAVAIL", Const, 3, ""},
		{"MADV_UNMERGEABLE", Const, 0, ""},
		{"MADV_WILLNEED", Const, 0, ""},
		{"MADV_ZERO_WIRED_PAGES", Const, 0, ""},
		{"MAP_32BIT", Const, 0, ""},
		{"MAP_ALIGNED_SUPER", Const, 3, ""},
		{"MAP_ALIGNMENT_16MB", Const, 3, ""},
		{"MAP_ALIGNMENT_1TB", Const, 3, ""},
		{"MAP_ALIGNMENT_256TB", Const, 3, ""},
		{"MAP_ALIGNMENT_4GB", Const, 3, ""},
		{"MAP_ALIGNMENT_64KB", Const, 3, ""},
		{"MAP_ALIGNMENT_64PB", Const, 3, ""},
		{"MAP_ALIGNMENT_MASK", Const, 3, ""},
		{"MAP_ALIGNMENT_SHIFT", Const, 3, ""},
		{"MAP_ANON", Const, 0, ""},
		{"MAP_ANONYMOUS", Const, 0, ""},
		{"MAP_COPY", Const, 0, ""},
		{"MAP_DENYWRITE", Const, 0, ""},
		{"MAP_EXECUTABLE", Const, 0, ""},
		{"MAP_FILE", Const, 0, ""},
		{"MAP_FIXED", Const, 0, ""},
		{"MAP_FLAGMASK", Const, 3, ""},
		{"MAP_GROWSDOWN", Const, 0, ""},
		{"MAP_HASSEMAPHORE", Const, 0, ""},
		{"MAP_HUGETLB", Const, 0, ""},
		{"MAP_INHERIT", Const, 3, ""},
		{"MAP_INHERIT_COPY", Const, 3, ""},
		{"MAP_INHERIT_DEFAULT", Const, 3, ""},
		{"MAP_INHERIT_DONATE_COPY", Const, 3, ""},
		{"MAP_INHERIT_NONE", Const, 3, ""},
		{"MAP_INHERIT_SHARE", Const, 3, ""},
		{"MAP_JIT", Const, 0, ""},
		{"MAP_LOCKED", Const, 0, ""},
		{"MAP_NOCACHE", Const, 0, ""},
		{"MAP_NOCORE", Const, 1, ""},
		{"MAP_NOEXTEND", Const, 0, ""},
		{"MAP_NONBLOCK", Const, 0, ""},
		{"MAP_NORESERVE", Const, 0, ""},
		{"MAP_NOSYNC", Const, 1, ""},
		{"MAP_POPULATE", Const, 0, ""},
		{"MAP_PREFAULT_READ", Const, 1, ""},
		{"MAP_PRIVATE", Const, 0, ""},
		{"MAP_RENAME", Const, 0, ""},
		{"MAP_RESERVED0080", Const, 0, ""},
		{"MAP_RESERVED0100", Const, 1, ""},
		{"MAP_SHARED", Const, 0, ""},
		{"MAP_STACK", Const, 0, ""},
		{"MAP_TRYFIXED", Const, 3, ""},
		{"MAP_TYPE", Const, 0, ""},
		{"MAP_WIRED", Const, 3, ""},
		{"MAXIMUM_REPARSE_DATA_BUFFER_SIZE", Const, 4, ""},
		{"MAXLEN_IFDESCR", Const, 0, ""},
		{"MAXLEN_PHYSADDR", Const, 0, ""},
		{"MAX_ADAPTER_ADDRESS_LENGTH", Const, 0, ""},
		{"MAX_ADAPTER_DESCRIPTION_LENGTH", Const, 0, ""},
		{"MAX_ADAPTER_NAME_LENGTH", Const, 0, ""},
		{"MAX_COMPUTERNAME_LENGTH", Const, 0, ""},
		{"MAX_INTERFACE_NAME_LEN", Const, 0, ""},
		{"MAX_LONG_PATH", Const, 0, ""},
		{"MAX_PATH", Const, 0, ""},
		{"MAX_PROTOCOL_CHAIN", Const, 2, ""},
		{"MCL_CURRENT", Const, 0, ""},
		{"MCL_FUTURE", Const, 0, ""},
		{"MNT_DETACH", Const, 0, ""},
		{"MNT_EXPIRE", Const, 0, ""},
		{"MNT_FORCE", Const, 0, ""},
		{"MSG_BCAST", Const, 1, ""},
		{"MSG_CMSG_CLOEXEC", Const, 0, ""},
		{"MSG_COMPAT", Const, 0, ""},
		{"MSG_CONFIRM", Const, 0, ""},
		{"MSG_CONTROLMBUF", Const, 1, ""},
		{"MSG_CTRUNC", Const, 0, ""},
		{"MSG_DONTROUTE", Const, 0, ""},
		{"MSG_DONTWAIT", Const, 0, ""},
		{"MSG_EOF", Const, 0, ""},
		{"MSG_EOR", Const, 0, ""},
		{"MSG_ERRQUEUE", Const, 0, ""},
		{"MSG_FASTOPEN", Const, 1, ""},
		{"MSG_FIN", Const, 0, ""},
		{"MSG_FLUSH", Const, 0, ""},
		{"MSG_HAVEMORE", Const, 0, ""},
		{"MSG_HOLD", Const, 0, ""},
		{"MSG_IOVUSRSPACE", Const, 1, ""},
		{"MSG_LENUSRSPACE", Const, 1, ""},
		{"MSG_MCAST", Const, 1, ""},
		{"MSG_MORE", Const, 0, ""},
		{"MSG_NAMEMBUF", Const, 1, ""},
		{"MSG_NBIO", Const, 0, ""},
		{"MSG_NEEDSA", Const, 0, ""},
		{"MSG_NOSIGNAL", Const, 0, ""},
		{"MSG_NOTIFICATION", Const, 0, ""},
		{"MSG_OOB", Const, 0, ""},
		{"MSG_PEEK", Const, 0, ""},
		{"MSG_PROXY", Const, 0, ""},
		{"MSG_RCVMORE", Const, 0, ""},
		{"MSG_RST", Const, 0, ""},
		{"MSG_SEND", Const, 0, ""},
		{"MSG_SYN", Const, 0, ""},
		{"MSG_TRUNC", Const, 0, ""},
		{"MSG_TRYHARD", Const, 0, ""},
		{"MSG_USERFLAGS", Const, 1, ""},
		{"MSG_WAITALL", Const, 0, ""},
		{"MSG_WAITFORONE", Const, 0, ""},
		{"MSG_WAITSTREAM", Const, 0, ""},
		{"MS_ACTIVE", Const, 0, ""},
		{"MS_ASYNC", Const, 0, ""},
		{"MS_BIND", Const, 0, ""},
		{"MS_DEACTIVATE", Const, 0, ""},
		{"MS_DIRSYNC", Const, 0, ""},
		{"MS_INVALIDATE", Const, 0, ""},
		{"MS_I_VERSION", Const, 0, ""},
		{"MS_KERNMOUNT", Const, 0, ""},
		{"MS_KILLPAGES", Const, 0, ""},
		{"MS_MANDLOCK", Const, 0, ""},
		{"MS_MGC_MSK", Const, 0, ""},
		{"MS_MGC_VAL", Const, 0, ""},
		{"MS_MOVE", Const, 0, ""},
		{"MS_NOATIME", Const, 0, ""},
		{"MS_NODEV", Const, 0, ""},
		{"MS_NODIRATIME", Const, 0, ""},
		{"MS_NOEXEC", Const, 0, ""},
		{"MS_NOSUID", Const, 0, ""},
		{"MS_NOUSER", Const, 0, ""},
		{"MS_POSIXACL", Const, 0, ""},
		{"MS_PRIVATE", Const, 0, ""},
		{"MS_RDONLY", Const, 0, ""},
		{"MS_REC", Const, 0, ""},
		{"MS_RELATIME", Const, 0, ""},
		{"MS_REMOUNT", Const, 0, ""},
		{"MS_RMT_MASK", Const, 0, ""},
		{"MS_SHARED", Const, 0, ""},
		{"MS_SILENT", Const, 0, ""},
		{"MS_SLAVE", Const, 0, ""},
		{"MS_STRICTATIME", Const, 0, ""},
		{"MS_SYNC", Const, 0, ""},
		{"MS_SYNCHRONOUS", Const, 0, ""},
		{"MS_UNBINDABLE", Const, 0, ""},
		{"Madvise", Func, 0, "func(b []byte, advice int) (err error)"},
		{"MapViewOfFile", Func, 0, ""},
		{"MaxTokenInfoClass", Const, 0, ""},
		{"Mclpool", Type, 2, ""},
		{"Mclpool.Alive", Field, 2, ""},
		{"Mclpool.Cwm", Field, 2, ""},
		{"Mclpool.Grown", Field, 2, ""},
		{"Mclpool.Hwm", Field, 2, ""},
		{"Mclpool.Lwm", Field, 2, ""},
		{"MibIfRow", Type, 0, ""},
		{"MibIfRow.AdminStatus", Field, 0, ""},
		{"MibIfRow.Descr", Field, 0, ""},
		{"MibIfRow.DescrLen", Field, 0, ""},
		{"MibIfRow.InDiscards", Field, 0, ""},
		{"MibIfRow.InErrors", Field, 0, ""},
		{"MibIfRow.InNUcastPkts", Field, 0, ""},
		{"MibIfRow.InOctets", Field, 0, ""},
		{"MibIfRow.InUcastPkts", Field, 0, ""},
		{"MibIfRow.InUnknownProtos", Field, 0, ""},
		{"MibIfRow.Index", Field, 0, ""},
		{"MibIfRow.LastChange", Field, 0, ""},
		{"MibIfRow.Mtu", Field, 0, ""},
		{"MibIfRow.Name", Field, 0, ""},
		{"MibIfRow.OperStatus", Field, 0, ""},
		{"MibIfRow.OutDiscards", Field, 0, ""},
		{"MibIfRow.OutErrors", Field, 0, ""},
		{"MibIfRow.OutNUcastPkts", Field, 0, ""},
		{"MibIfRow.OutOctets", Field, 0, ""},
		{"MibIfRow.OutQLen", Field, 0, ""},
		{"MibIfRow.OutUcastPkts", Field, 0, ""},
		{"MibIfRow.PhysAddr", Field, 0, ""},
		{"MibIfRow.PhysAddrLen", Field, 0, ""},
		{"MibIfRow.Speed", Field, 0, ""},
		{"MibIfRow.Type", Field, 0, ""},
		{"Mkdir", Func, 0, "func(path string, mode uint32) (err error)"},
		{"Mkdirat", Func, 0, "func(dirfd int, path string, mode uint32) (err error)"},
		{"Mkfifo", Func, 0, "func(path string, mode uint32) (err error)"},
		{"Mknod", Func, 0, "func(path string, mode uint32, dev int) (err error)"},
		{"Mknodat", Func, 0, "func(dirfd int, path string, mode uint32, dev int) (err error)"},
		{"Mlock", Func, 0, "func(b []byte) (err error)"},
		{"Mlockall", Func, 0, "func(flags int) (err error)"},
		{"Mmap", Func, 0, "func(fd int, offset int64, length int, prot int, flags int) (data []byte, err error)"},
		{"Mount", Func, 0, "func(source string, target string, fstype string, flags uintptr, data string) (err error)"},
		{"MoveFile", Func, 0, ""},
		{"Mprotect", Func, 0, "func(b []byte, prot int) (err error)"},
		{"Msghdr", Type, 0, ""},
		{"Msghdr.Control", Field, 0, ""},
		{"Msghdr.Controllen", Field, 0, ""},
		{"Msghdr.Flags", Field, 0, ""},
		{"Msghdr.Iov", Field, 0, ""},
		{"Msghdr.Iovlen", Field, 0, ""},
		{"Msghdr.Name", Field, 0, ""},
		{"Msghdr.Namelen", Field, 0, ""},
		{"Msghdr.Pad_cgo_0", Field, 0, ""},
		{"Msghdr.Pad_cgo_1", Field, 0, ""},
		{"Munlock", Func, 0, "func(b []byte) (err error)"},
		{"Munlockall", Func, 0, "func() (err error)"},
		{"Munmap", Func, 0, "func(b []byte) (err error)"},
		{"MustLoadDLL", Func, 0, ""},
		{"NAME_MAX", Const, 0, ""},
		{"NETLINK_ADD_MEMBERSHIP", Const, 0, ""},
		{"NETLINK_AUDIT", Const, 0, ""},
		{"NETLINK_BROADCAST_ERROR", Const, 0, ""},
		{"NETLINK_CONNECTOR", Const, 0, ""},
		{"NETLINK_DNRTMSG", Const, 0, ""},
		{"NETLINK_DROP_MEMBERSHIP", Const, 0, ""},
		{"NETLINK_ECRYPTFS", Const, 0, ""},
		{"NETLINK_FIB_LOOKUP", Const, 0, ""},
		{"NETLINK_FIREWALL", Const, 0, ""},
		{"NETLINK_GENERIC", Const, 0, ""},
		{"NETLINK_INET_DIAG", Const, 0, ""},
		{"NETLINK_IP6_FW", Const, 0, ""},
		{"NETLINK_ISCSI", Const, 0, ""},
		{"NETLINK_KOBJECT_UEVENT", Const, 0, ""},
		{"NETLINK_NETFILTER", Const, 0, ""},
		{"NETLINK_NFLOG", Const, 0, ""},
		{"NETLINK_NO_ENOBUFS", Const, 0, ""},
		{"NETLINK_PKTINFO", Const, 0, ""},
		{"NETLINK_RDMA", Const, 0, ""},
		{"NETLINK_ROUTE", Const, 0, ""},
		{"NETLINK_SCSITRANSPORT", Const, 0, ""},
		{"NETLINK_SELINUX", Const, 0, ""},
		{"NETLINK_UNUSED", Const, 0, ""},
		{"NETLINK_USERSOCK", Const, 0, ""},
		{"NETLINK_XFRM", Const, 0, ""},
		{"NET_RT_DUMP", Const, 0, ""},
		{"NET_RT_DUMP2", Const, 0, ""},
		{"NET_RT_FLAGS", Const, 0, ""},
		{"NET_RT_IFLIST", Const, 0, ""},
		{"NET_RT_IFLIST2", Const, 0, ""},
		{"NET_RT_IFLISTL", Const, 1, ""},
		{"NET_RT_IFMALIST", Const, 0, ""},
		{"NET_RT_MAXID", Const, 0, ""},
		{"NET_RT_OIFLIST", Const, 1, ""},
		{"NET_RT_OOIFLIST", Const, 1, ""},
		{"NET_RT_STAT", Const, 0, ""},
		{"NET_RT_STATS", Const, 1, ""},
		{"NET_RT_TABLE", Const, 1, ""},
		{"NET_RT_TRASH", Const, 0, ""},
		{"NLA_ALIGNTO", Const, 0, ""},
		{"NLA_F_NESTED", Const, 0, ""},
		{"NLA_F_NET_BYTEORDER", Const, 0, ""},
		{"NLA_HDRLEN", Const, 0, ""},
		{"NLMSG_ALIGNTO", Const, 0, ""},
		{"NLMSG_DONE", Const, 0, ""},
		{"NLMSG_ERROR", Const, 0, ""},
		{"NLMSG_HDRLEN", Const, 0, ""},
		{"NLMSG_MIN_TYPE", Const, 0, ""},
		{"NLMSG_NOOP", Const, 0, ""},
		{"NLMSG_OVERRUN", Const, 0, ""},
		{"NLM_F_ACK", Const, 0, ""},
		{"NLM_F_APPEND", Const, 0, ""},
		{"NLM_F_ATOMIC", Const, 0, ""},
		{"NLM_F_CREATE", Const, 0, ""},
		{"NLM_F_DUMP", Const, 0, ""},
		{"NLM_F_ECHO", Const, 0, ""},
		{"NLM_F_EXCL", Const, 0, ""},
		{"NLM_F_MATCH", Const, 0, ""},
		{"NLM_F_MULTI", Const, 0, ""},
		{"NLM_F_REPLACE", Const, 0, ""},
		{"NLM_F_REQUEST", Const, 0, ""},
		{"NLM_F_ROOT", Const, 0, ""},
		{"NOFLSH", Const, 0, ""},
		{"NOTE_ABSOLUTE", Const, 0, ""},
		{"NOTE_ATTRIB", Const, 0, ""},
		{"NOTE_BACKGROUND", Const, 16, ""},
		{"NOTE_CHILD", Const, 0, ""},
		{"NOTE_CRITICAL", Const, 16, ""},
		{"NOTE_DELETE", Const, 0, ""},
		{"NOTE_EOF", Const, 1, ""},
		{"NOTE_EXEC", Const, 0, ""},
		{"NOTE_EXIT", Const, 0, ""},
		{"NOTE_EXITSTATUS", Const, 0, ""},
		{"NOTE_EXIT_CSERROR", Const, 16, ""},
		{"NOTE_EXIT_DECRYPTFAIL", Const, 16, ""},
		{"NOTE_EXIT_DETAIL", Const, 16, ""},
		{"NOTE_EXIT_DETAIL_MASK", Const, 16, ""},
		{"NOTE_EXIT_MEMORY", Const, 16, ""},
		{"NOTE_EXIT_REPARENTED", Const, 16, ""},
		{"NOTE_EXTEND", Const, 0, ""},
		{"NOTE_FFAND", Const, 0, ""},
		{"NOTE_FFCOPY", Const, 0, ""},
		{"NOTE_FFCTRLMASK", Const, 0, ""},
		{"NOTE_FFLAGSMASK", Const, 0, ""},
		{"NOTE_FFNOP", Const, 0, ""},
		{"NOTE_FFOR", Const, 0, ""},
		{"NOTE_FORK", Const, 0, ""},
		{"NOTE_LEEWAY", Const, 16, ""},
		{"NOTE_LINK", Const, 0, ""},
		{"NOTE_LOWAT", Const, 0, ""},
		{"NOTE_NONE", Const, 0, ""},
		{"NOTE_NSECONDS", Const, 0, ""},
		{"NOTE_PCTRLMASK", Const, 0, ""},
		{"NOTE_PDATAMASK", Const, 0, ""},
		{"NOTE_REAP", Const, 0, ""},
		{"NOTE_RENAME", Const, 0, ""},
		{"NOTE_RESOURCEEND", Const, 0, ""},
		{"NOTE_REVOKE", Const, 0, ""},
		{"NOTE_SECONDS", Const, 0, ""},
		{"NOTE_SIGNAL", Const, 0, ""},
		{"NOTE_TRACK", Const, 0, ""},
		{"NOTE_TRACKERR", Const, 0, ""},
		{"NOTE_TRIGGER", Const, 0, ""},
		{"NOTE_TRUNCATE", Const, 1, ""},
		{"NOTE_USECONDS", Const, 0, ""},
		{"NOTE_VM_ERROR", Const, 0, ""},
		{"NOTE_VM_PRESSURE", Const, 0, ""},
		{"NOTE_VM_PRESSURE_SUDDEN_TERMINATE", Const, 0, ""},
		{"NOTE_VM_PRESSURE_TERMINATE", Const, 0, ""},
		{"NOTE_WRITE", Const, 0, ""},
		{"NameCanonical", Const, 0, ""},
		{"NameCanonicalEx", Const, 0, ""},
		{"NameDisplay", Const, 0, ""},
		{"NameDnsDomain", Const, 0, ""},
		{"NameFullyQualifiedDN", Const, 0, ""},
		{"NameSamCompatible", Const, 0, ""},
		{"NameServicePrincipal", Const, 0, ""},
		{"NameUniqueId", Const, 0, ""},
		{"NameUnknown", Const, 0, ""},
		{"NameUserPrincipal", Const, 0, ""},
		{"Nanosleep", Func, 0, "func(time *Timespec, leftover *Timespec) (err error)"},
		{"NetApiBufferFree", Func, 0, ""},
		{"NetGetJoinInformation", Func, 2, ""},
		{"NetSetupDomainName", Const, 2, ""},
		{"NetSetupUnjoined", Const, 2, ""},
		{"NetSetupUnknownStatus", Const, 2, ""},
		{"NetSetupWorkgroupName", Const, 2, ""},
		{"NetUserGetInfo", Func, 0, ""},
		{"NetlinkMessage", Type, 0, ""},
		{"NetlinkMessage.Data", Field, 0, ""},
		{"NetlinkMessage.Header", Field, 0, ""},
		{"NetlinkRIB", Func, 0, "func(proto int, family int) ([]byte, error)"},
		{"NetlinkRouteAttr", Type, 0, ""},
		{"NetlinkRouteAttr.Attr", Field, 0, ""},
		{"NetlinkRouteAttr.Value", Field, 0, ""},
		{"NetlinkRouteRequest", Type, 0, ""},
		{"NetlinkRouteRequest.Data", Field, 0, ""},
		{"NetlinkRouteRequest.Header", Field, 0, ""},
		{"NewCallback", Func, 0, ""},
		{"NewCallbackCDecl", Func, 3, ""},
		{"NewLazyDLL", Func, 0, ""},
		{"NlAttr", Type, 0, ""},
		{"NlAttr.Len", Field, 0, ""},
		{"NlAttr.Type", Field, 0, ""},
		{"NlMsgerr", Type, 0, ""},
		{"NlMsgerr.Error", Field, 0, ""},
		{"NlMsgerr.Msg", Field, 0, ""},
		{"NlMsghdr", Type, 0, ""},
		{"NlMsghdr.Flags", Field, 0, ""},
		{"NlMsghdr.Len", Field, 0, ""},
		{"NlMsghdr.Pid", Field, 0, ""},
		{"NlMsghdr.Seq", Field, 0, ""},
		{"NlMsghdr.Type", Field, 0, ""},
		{"NsecToFiletime", Func, 0, ""},
		{"NsecToTimespec", Func, 0, "func(nsec int64) Timespec"},
		{"NsecToTimeval", Func, 0, "func(nsec int64) Timeval"},
		{"Ntohs", Func, 0, ""},
		{"OCRNL", Const, 0, ""},
		{"OFDEL", Const, 0, ""},
		{"OFILL", Const, 0, ""},
		{"OFIOGETBMAP", Const, 1, ""},
		{"OID_PKIX_KP_SERVER_AUTH", Var, 0, ""},
		{"OID_SERVER_GATED_CRYPTO", Var, 0, ""},
		{"OID_SGC_NETSCAPE", Var, 0, ""},
		{"OLCUC", Const, 0, ""},
		{"ONLCR", Const, 0, ""},
		{"ONLRET", Const, 0, ""},
		{"ONOCR", Const, 0, ""},
		{"ONOEOT", Const, 1, ""},
		{"OPEN_ALWAYS", Const, 0, ""},
		{"OPEN_EXISTING", Const, 0, ""},
		{"OPOST", Const, 0, ""},
		{"O_ACCMODE", Const, 0, ""},
		{"O_ALERT", Const, 0, ""},
		{"O_ALT_IO", Const, 1, ""},
		{"O_APPEND", Const, 0, ""},
		{"O_ASYNC", Const, 0, ""},
		{"O_CLOEXEC", Const, 0, ""},
		{"O_CREAT", Const, 0, ""},
		{"O_DIRECT", Const, 0, ""},
		{"O_DIRECTORY", Const, 0, ""},
		{"O_DP_GETRAWENCRYPTED", Const, 16, ""},
		{"O_DSYNC", Const, 0, ""},
		{"O_EVTONLY", Const, 0, ""},
		{"O_EXCL", Const, 0, ""},
		{"O_EXEC", Const, 0, ""},
		{"O_EXLOCK", Const, 0, ""},
		{"O_FSYNC", Const, 0, ""},
		{"O_LARGEFILE", Const, 0, ""},
		{"O_NDELAY", Const, 0, ""},
		{"O_NOATIME", Const, 0, ""},
		{"O_NOCTTY", Const, 0, ""},
		{"O_NOFOLLOW", Const, 0, ""},
		{"O_NONBLOCK", Const, 0, ""},
		{"O_NOSIGPIPE", Const, 1, ""},
		{"O_POPUP", Const, 0, ""},
		{"O_RDONLY", Const, 0, ""},
		{"O_RDWR", Const, 0, ""},
		{"O_RSYNC", Const, 0, ""},
		{"O_SHLOCK", Const, 0, ""},
		{"O_SYMLINK", Const, 0, ""},
		{"O_SYNC", Const, 0, ""},
		{"O_TRUNC", Const, 0, ""},
		{"O_TTY_INIT", Const, 0, ""},
		{"O_WRONLY", Const, 0, ""},
		{"Open", Func, 0, "func(path string, mode int, perm uint32) (fd int, err error)"},
		{"OpenCurrentProcessToken", Func, 0, ""},
		{"OpenProcess", Func, 0, ""},
		{"OpenProcessToken", Func, 0, ""},
		{"Openat", Func, 0, "func(dirfd int, path string, flags int, mode uint32) (fd int, err error)"},
		{"Overlapped", Type, 0, ""},
		{"Overlapped.HEvent", Field, 0, ""},
		{"Overlapped.Internal", Field, 0, ""},
		{"Overlapped.InternalHigh", Field, 0, ""},
		{"Overlapped.Offset", Field, 0, ""},
		{"Overlapped.OffsetHigh", Field, 0, ""},
		{"PACKET_ADD_MEMBERSHIP", Const, 0, ""},
		{"PACKET_BROADCAST", Const, 0, ""},
		{"PACKET_DROP_MEMBERSHIP", Const, 0, ""},
		{"PACKET_FASTROUTE", Const, 0, ""},
		{"PACKET_HOST", Const, 0, ""},
		{"PACKET_LOOPBACK", Const, 0, ""},
		{"PACKET_MR_ALLMULTI", Const, 0, ""},
		{"PACKET_MR_MULTICAST", Const, 0, ""},
		{"PACKET_MR_PROMISC", Const, 0, ""},
		{"PACKET_MULTICAST", Const, 0, ""},
		{"PACKET_OTHERHOST", Const, 0, ""},
		{"PACKET_OUTGOING", Const, 0, ""},
		{"PACKET_RECV_OUTPUT", Const, 0, ""},
		{"PACKET_RX_RING", Const, 0, ""},
		{"PACKET_STATISTICS", Const, 0, ""},
		{"PAGE_EXECUTE_READ", Const, 0, ""},
		{"PAGE_EXECUTE_READWRITE", Const, 0, ""},
		{"PAGE_EXECUTE_WRITECOPY", Const, 0, ""},
		{"PAGE_READONLY", Const, 0, ""},
		{"PAGE_READWRITE", Const, 0, ""},
		{"PAGE_WRITECOPY", Const, 0, ""},
		{"PARENB", Const, 0, ""},
		{"PARMRK", Const, 0, ""},
		{"PARODD", Const, 0, ""},
		{"PENDIN", Const, 0, ""},
		{"PFL_HIDDEN", Const, 2, ""},
		{"PFL_MATCHES_PROTOCOL_ZERO", Const, 2, ""},
		{"PFL_MULTIPLE_PROTO_ENTRIES", Const, 2, ""},
		{"PFL_NETWORKDIRECT_PROVIDER", Const, 2, ""},
		{"PFL_RECOMMENDED_PROTO_ENTRY", Const, 2, ""},
		{"PF_FLUSH", Const, 1, ""},
		{"PKCS_7_ASN_ENCODING", Const, 0, ""},
		{"PMC5_PIPELINE_FLUSH", Const, 1, ""},
		{"PRIO_PGRP", Const, 2, ""},
		{"PRIO_PROCESS", Const, 2, ""},
		{"PRIO_USER", Const, 2, ""},
		{"PRI_IOFLUSH", Const, 1, ""},
		{"PROCESS_QUERY_INFORMATION", Const, 0, ""},
		{"PROCESS_TERMINATE", Const, 2, ""},
		{"PROT_EXEC", Const, 0, ""},
		{"PROT_GROWSDOWN", Const, 0, ""},
		{"PROT_GROWSUP", Const, 0, ""},
		{"PROT_NONE", Const, 0, ""},
		{"PROT_READ", Const, 0, ""},
		{"PROT_WRITE", Const, 0, ""},
		{"PROV_DH_SCHANNEL", Const, 0, ""},
		{"PROV_DSS", Const, 0, ""},
		{"PROV_DSS_DH", Const, 0, ""},
		{"PROV_EC_ECDSA_FULL", Const, 0, ""},
		{"PROV_EC_ECDSA_SIG", Const, 0, ""},
		{"PROV_EC_ECNRA_FULL", Const, 0, ""},
		{"PROV_EC_ECNRA_SIG", Const, 0, ""},
		{"PROV_FORTEZZA", Const, 0, ""},
		{"PROV_INTEL_SEC", Const, 0, ""},
		{"PROV_MS_EXCHANGE", Const, 0, ""},
		{"PROV_REPLACE_OWF", Const, 0, ""},
		{"PROV_RNG", Const, 0, ""},
		{"PROV_RSA_AES", Const, 0, ""},
		{"PROV_RSA_FULL", Const, 0, ""},
		{"PROV_RSA_SCHANNEL", Const, 0, ""},
		{"PROV_RSA_SIG", Const, 0, ""},
		{"PROV_SPYRUS_LYNKS", Const, 0, ""},
		{"PROV_SSL", Const, 0, ""},
		{"PR_CAPBSET_DROP", Const, 0, ""},
		{"PR_CAPBSET_READ", Const, 0, ""},
		{"PR_CLEAR_SECCOMP_FILTER", Const, 0, ""},
		{"PR_ENDIAN_BIG", Const, 0, ""},
		{"PR_ENDIAN_LITTLE", Const, 0, ""},
		{"PR_ENDIAN_PPC_LITTLE", Const, 0, ""},
		{"PR_FPEMU_NOPRINT", Const, 0, ""},
		{"PR_FPEMU_SIGFPE", Const, 0, ""},
		{"PR_FP_EXC_ASYNC", Const, 0, ""},
		{"PR_FP_EXC_DISABLED", Const, 0, ""},
		{"PR_FP_EXC_DIV", Const, 0, ""},
		{"PR_FP_EXC_INV", Const, 0, ""},
		{"PR_FP_EXC_NONRECOV", Const, 0, ""},
		{"PR_FP_EXC_OVF", Const, 0, ""},
		{"PR_FP_EXC_PRECISE", Const, 0, ""},
		{"PR_FP_EXC_RES", Const, 0, ""},
		{"PR_FP_EXC_SW_ENABLE", Const, 0, ""},
		{"PR_FP_EXC_UND", Const, 0, ""},
		{"PR_GET_DUMPABLE", Const, 0, ""},
		{"PR_GET_ENDIAN", Const, 0, ""},
		{"PR_GET_FPEMU", Const, 0, ""},
		{"PR_GET_FPEXC", Const, 0, ""},
		{"PR_GET_KEEPCAPS", Const, 0, ""},
		{"PR_GET_NAME", Const, 0, ""},
		{"PR_GET_PDEATHSIG", Const, 0, ""},
		{"PR_GET_SECCOMP", Const, 0, ""},
		{"PR_GET_SECCOMP_FILTER", Const, 0, ""},
		{"PR_GET_SECUREBITS", Const, 0, ""},
		{"PR_GET_TIMERSLACK", Const, 0, ""},
		{"PR_GET_TIMING", Const, 0, ""},
		{"PR_GET_TSC", Const, 0, ""},
		{"PR_GET_UNALIGN", Const, 0, ""},
		{"PR_MCE_KILL", Const, 0, ""},
		{"PR_MCE_KILL_CLEAR", Const, 0, ""},
		{"PR_MCE_KILL_DEFAULT", Const, 0, ""},
		{"PR_MCE_KILL_EARLY", Const, 0, ""},
		{"PR_MCE_KILL_GET", Const, 0, ""},
		{"PR_MCE_KILL_LATE", Const, 0, ""},
		{"PR_MCE_KILL_SET", Const, 0, ""},
		{"PR_SECCOMP_FILTER_EVENT", Const, 0, ""},
		{"PR_SECCOMP_FILTER_SYSCALL", Const, 0, ""},
		{"PR_SET_DUMPABLE", Const, 0, ""},
		{"PR_SET_ENDIAN", Const, 0, ""},
		{"PR_SET_FPEMU", Const, 0, ""},
		{"PR_SET_FPEXC", Const, 0, ""},
		{"PR_SET_KEEPCAPS", Const, 0, ""},
		{"PR_SET_NAME", Const, 0, ""},
		{"PR_SET_PDEATHSIG", Const, 0, ""},
		{"PR_SET_PTRACER", Const, 0, ""},
		{"PR_SET_SECCOMP", Const, 0, ""},
		{"PR_SET_SECCOMP_FILTER", Const, 0, ""},
		{"PR_SET_SECUREBITS", Const, 0, ""},
		{"PR_SET_TIMERSLACK", Const, 0, ""},
		{"PR_SET_TIMING", Const, 0, ""},
		{"PR_SET_TSC", Const, 0, ""},
		{"PR_SET_UNALIGN", Const, 0, ""},
		{"PR_TASK_PERF_EVENTS_DISABLE", Const, 0, ""},
		{"PR_TASK_PERF_EVENTS_ENABLE", Const, 0, ""},
		{"PR_TIMING_STATISTICAL", Const, 0, ""},
		{"PR_TIMING_TIMESTAMP", Const, 0, ""},
		{"PR_TSC_ENABLE", Const, 0, ""},
		{"PR_TSC_SIGSEGV", Const, 0, ""},
		{"PR_UNALIGN_NOPRINT", Const, 0, ""},
		{"PR_UNALIGN_SIGBUS", Const, 0, ""},
		{"PTRACE_ARCH_PRCTL", Const, 0, ""},
		{"PTRACE_ATTACH", Const, 0, ""},
		{"PTRACE_CONT", Const, 0, ""},
		{"PTRACE_DETACH", Const, 0, ""},
		{"PTRACE_EVENT_CLONE", Const, 0, ""},
		{"PTRACE_EVENT_EXEC", Const, 0, ""},
		{"PTRACE_EVENT_EXIT", Const, 0, ""},
		{"PTRACE_EVENT_FORK", Const, 0, ""},
		{"PTRACE_EVENT_VFORK", Const, 0, ""},
		{"PTRACE_EVENT_VFORK_DONE", Const, 0, ""},
		{"PTRACE_GETCRUNCHREGS", Const, 0, ""},
		{"PTRACE_GETEVENTMSG", Const, 0, ""},
		{"PTRACE_GETFPREGS", Const, 0, ""},
		{"PTRACE_GETFPXREGS", Const, 0, ""},
		{"PTRACE_GETHBPREGS", Const, 0, ""},
		{"PTRACE_GETREGS", Const, 0, ""},
		{"PTRACE_GETREGSET", Const, 0, ""},
		{"PTRACE_GETSIGINFO", Const, 0, ""},
		{"PTRACE_GETVFPREGS", Const, 0, ""},
		{"PTRACE_GETWMMXREGS", Const, 0, ""},
		{"PTRACE_GET_THREAD_AREA", Const, 0, ""},
		{"PTRACE_KILL", Const, 0, ""},
		{"PTRACE_OLDSETOPTIONS", Const, 0, ""},
		{"PTRACE_O_MASK", Const, 0, ""},
		{"PTRACE_O_TRACECLONE", Const, 0, ""},
		{"PTRACE_O_TRACEEXEC", Const, 0, ""},
		{"PTRACE_O_TRACEEXIT", Const, 0, ""},
		{"PTRACE_O_TRACEFORK", Const, 0, ""},
		{"PTRACE_O_TRACESYSGOOD", Const, 0, ""},
		{"PTRACE_O_TRACEVFORK", Const, 0, ""},
		{"PTRACE_O_TRACEVFORKDONE", Const, 0, ""},
		{"PTRACE_PEEKDATA", Const, 0, ""},
		{"PTRACE_PEEKTEXT", Const, 0, ""},
		{"PTRACE_PEEKUSR", Const, 0, ""},
		{"PTRACE_POKEDATA", Const, 0, ""},
		{"PTRACE_POKETEXT", Const, 0, ""},
		{"PTRACE_POKEUSR", Const, 0, ""},
		{"PTRACE_SETCRUNCHREGS", Const, 0, ""},
		{"PTRACE_SETFPREGS", Const, 0, ""},
		{"PTRACE_SETFPXREGS", Const, 0, ""},
		{"PTRACE_SETHBPREGS", Const, 0, ""},
		{"PTRACE_SETOPTIONS", Const, 0, ""},
		{"PTRACE_SETREGS", Const, 0, ""},
		{"PTRACE_SETREGSET", Const, 0, ""},
		{"PTRACE_SETSIGINFO", Const, 0, ""},
		{"PTRACE_SETVFPREGS", Const, 0, ""},
		{"PTRACE_SETWMMXREGS", Const, 0, ""},
		{"PTRACE_SET_SYSCALL", Const, 0, ""},
		{"PTRACE_SET_THREAD_AREA", Const, 0, ""},
		{"PTRACE_SINGLEBLOCK", Const, 0, ""},
		{"PTRACE_SINGLESTEP", Const, 0, ""},
		{"PTRACE_SYSCALL", Const, 0, ""},
		{"PTRACE_SYSEMU", Const, 0, ""},
		{"PTRACE_SYSEMU_SINGLESTEP", Const, 0, ""},
		{"PTRACE_TRACEME", Const, 0, ""},
		{"PT_ATTACH", Const, 0, ""},
		{"PT_ATTACHEXC", Const, 0, ""},
		{"PT_CONTINUE", Const, 0, ""},
		{"PT_DATA_ADDR", Const, 0, ""},
		{"PT_DENY_ATTACH", Const, 0, ""},
		{"PT_DETACH", Const, 0, ""},
		{"PT_FIRSTMACH", Const, 0, ""},
		{"PT_FORCEQUOTA", Const, 0, ""},
		{"PT_KILL", Const, 0, ""},
		{"PT_MASK", Const, 1, ""},
		{"PT_READ_D", Const, 0, ""},
		{"PT_READ_I", Const, 0, ""},
		{"PT_READ_U", Const, 0, ""},
		{"PT_SIGEXC", Const, 0, ""},
		{"PT_STEP", Const, 0, ""},
		{"PT_TEXT_ADDR", Const, 0, ""},
		{"PT_TEXT_END_ADDR", Const, 0, ""},
		{"PT_THUPDATE", Const, 0, ""},
		{"PT_TRACE_ME", Const, 0, ""},
		{"PT_WRITE_D", Const, 0, ""},
		{"PT_WRITE_I", Const, 0, ""},
		{"PT_WRITE_U", Const, 0, ""},
		{"ParseDirent", Func, 0, "func(buf []byte, max int, names []string) (consumed int, count int, newnames []string)"},
		{"ParseNetlinkMessage", Func, 0, "func(b []byte) ([]NetlinkMessage, error)"},
		{"ParseNetlinkRouteAttr", Func, 0, "func(m *NetlinkMessage) ([]NetlinkRouteAttr, error)"},
		{"ParseRoutingMessage", Func, 0, ""},
		{"ParseRoutingSockaddr", Func, 0, ""},
		{"ParseSocketControlMessage", Func, 0, "func(b []byte) ([]SocketControlMessage, error)"},
		{"ParseUnixCredentials", Func, 0, "func(m *SocketControlMessage) (*Ucred, error)"},
		{"ParseUnixRights", Func, 0, "func(m *SocketControlMessage) ([]int, error)"},
		{"PathMax", Const, 0, ""},
		{"Pathconf", Func, 0, ""},
		{"Pause", Func, 0, "func() (err error)"},
		{"Pipe", Func, 0, "func(p []int) error"},
		{"Pipe2", Func, 1, "func(p []int, flags int) error"},
		{"PivotRoot", Func, 0, "func(newroot string, putold string) (err error)"},
		{"Pointer", Type, 11, ""},
		{"PostQueuedCompletionStatus", Func, 0, ""},
		{"Pread", Func, 0, "func(fd int, p []byte, offset int64) (n int, err error)"},
		{"Proc", Type, 0, ""},
		{"Proc.Dll", Field, 0, ""},
		{"Proc.Name", Field, 0, ""},
		{"ProcAttr", Type, 0, ""},
		{"ProcAttr.Dir", Field, 0, ""},
		{"ProcAttr.Env", Field, 0, ""},
		{"ProcAttr.Files", Field, 0, ""},
		{"ProcAttr.Sys", Field, 0, ""},
		{"Process32First", Func, 4, ""},
		{"Process32Next", Func, 4, ""},
		{"ProcessEntry32", Type, 4, ""},
		{"ProcessEntry32.DefaultHeapID", Field, 4, ""},
		{"ProcessEntry32.ExeFile", Field, 4, ""},
		{"ProcessEntry32.Flags", Field, 4, ""},
		{"ProcessEntry32.ModuleID", Field, 4, ""},
		{"ProcessEntry32.ParentProcessID", Field, 4, ""},
		{"ProcessEntry32.PriClassBase", Field, 4, ""},
		{"ProcessEntry32.ProcessID", Field, 4, ""},
		{"ProcessEntry32.Size", Field, 4, ""},
		{"ProcessEntry32.Threads", Field, 4, ""},
		{"ProcessEntry32.Usage", Field, 4, ""},
		{"ProcessInformation", Type, 0, ""},
		{"ProcessInformation.Process", Field, 0, ""},
		{"ProcessInformation.ProcessId", Field, 0, ""},
		{"ProcessInformation.Thread", Field, 0, ""},
		{"ProcessInformation.ThreadId", Field, 0, ""},
		{"Protoent", Type, 0, ""},
		{"Protoent.Aliases", Field, 0, ""},
		{"Protoent.Name", Field, 0, ""},
		{"Protoent.Proto", Field, 0, ""},
		{"PtraceAttach", Func, 0, "func(pid int) (err error)"},
		{"PtraceCont", Func, 0, "func(pid int, signal int) (err error)"},
		{"PtraceDetach", Func, 0, "func(pid int) (err error)"},
		{"PtraceGetEventMsg", Func, 0, "func(pid int) (msg uint, err error)"},
		{"PtraceGetRegs", Func, 0, "func(pid int, regsout *PtraceRegs) (err error)"},
		{"PtracePeekData", Func, 0, "func(pid int, addr uintptr, out []byte) (count int, err error)"},
		{"PtracePeekText", Func, 0, "func(pid int, addr uintptr, out []byte) (count int, err error)"},
		{"PtracePokeData", Func, 0, "func(pid int, addr uintptr, data []byte) (count int, err error)"},
		{"PtracePokeText", Func, 0, "func(pid int, addr uintptr, data []byte) (count int, err error)"},
		{"PtraceRegs", Type, 0, ""},
		{"PtraceRegs.Cs", Field, 0, ""},
		{"PtraceRegs.Ds", Field, 0, ""},
		{"PtraceRegs.Eax", Field, 0, ""},
		{"PtraceRegs.Ebp", Field, 0, ""},
		{"PtraceRegs.Ebx", Field, 0, ""},
		{"PtraceRegs.Ecx", Field, 0, ""},
		{"PtraceRegs.Edi", Field, 0, ""},
		{"PtraceRegs.Edx", Field, 0, ""},
		{"PtraceRegs.Eflags", Field, 0, ""},
		{"PtraceRegs.Eip", Field, 0, ""},
		{"PtraceRegs.Es", Field, 0, ""},
		{"PtraceRegs.Esi", Field, 0, ""},
		{"PtraceRegs.Esp", Field, 0, ""},
		{"PtraceRegs.Fs", Field, 0, ""},
		{"PtraceRegs.Fs_base", Field, 0, ""},
		{"PtraceRegs.Gs", Field, 0, ""},
		{"PtraceRegs.Gs_base", Field, 0, ""},
		{"PtraceRegs.Orig_eax", Field, 0, ""},
		{"PtraceRegs.Orig_rax", Field, 0, ""},
		{"PtraceRegs.R10", Field, 0, ""},
		{"PtraceRegs.R11", Field, 0, ""},
		{"PtraceRegs.R12", Field, 0, ""},
		{"PtraceRegs.R13", Field, 0, ""},
		{"PtraceRegs.R14", Field, 0, ""},
		{"PtraceRegs.R15", Field, 0, ""},
		{"PtraceRegs.R8", Field, 0, ""},
		{"PtraceRegs.R9", Field, 0, ""},
		{"PtraceRegs.Rax", Field, 0, ""},
		{"PtraceRegs.Rbp", Field, 0, ""},
		{"PtraceRegs.Rbx", Field, 0, ""},
		{"PtraceRegs.Rcx", Field, 0, ""},
		{"PtraceRegs.Rdi", Field, 0, ""},
		{"PtraceRegs.Rdx", Field, 0, ""},
		{"PtraceRegs.Rip", Field, 0, ""},
		{"PtraceRegs.Rsi", Field, 0, ""},
		{"PtraceRegs.Rsp", Field, 0, ""},
		{"PtraceRegs.Ss", Field, 0, ""},
		{"PtraceRegs.Uregs", Field, 0, ""},
		{"PtraceRegs.Xcs", Field, 0, ""},
		{"PtraceRegs.Xds", Field, 0, ""},
		{"PtraceRegs.Xes", Field, 0, ""},
		{"PtraceRegs.Xfs", Field, 0, ""},
		{"PtraceRegs.Xgs", Field, 0, ""},
		{"PtraceRegs.Xss", Field, 0, ""},
		{"PtraceSetOptions", Func, 0, "func(pid int, options int) (err error)"},
		{"PtraceSetRegs", Func, 0, "func(pid int, regs *PtraceRegs) (err error)"},
		{"PtraceSingleStep", Func, 0, "func(pid int) (err error)"},
		{"PtraceSyscall", Func, 1, "func(pid int, signal int) (err error)"},
		{"Pwrite", Func, 0, "func(fd int, p []byte, offset int64) (n int, err error)"},
		{"REG_BINARY", Const, 0, ""},
		{"REG_DWORD", Const, 0, ""},
		{"REG_DWORD_BIG_ENDIAN", Const, 0, ""},
		{"REG_DWORD_LITTLE_ENDIAN", Const, 0, ""},
		{"REG_EXPAND_SZ", Const, 0, ""},
		{"REG_FULL_RESOURCE_DESCRIPTOR", Const, 0, ""},
		{"REG_LINK", Const, 0, ""},
		{"REG_MULTI_SZ", Const, 0, ""},
		{"REG_NONE", Const, 0, ""},
		{"REG_QWORD", Const, 0, ""},
		{"REG_QWORD_LITTLE_ENDIAN", Const, 0, ""},
		{"REG_RESOURCE_LIST", Const, 0, ""},
		{"REG_RESOURCE_REQUIREMENTS_LIST", Const, 0, ""},
		{"REG_SZ", Const, 0, ""},
		{"RLIMIT_AS", Const, 0, ""},
		{"RLIMIT_CORE", Const, 0, ""},
		{"RLIMIT_CPU", Const, 0, ""},
		{"RLIMIT_CPU_USAGE_MONITOR", Const, 16, ""},
		{"RLIMIT_DATA", Const, 0, ""},
		{"RLIMIT_FSIZE", Const, 0, ""},
		{"RLIMIT_NOFILE", Const, 0, ""},
		{"RLIMIT_STACK", Const, 0, ""},
		{"RLIM_INFINITY", Const, 0, ""},
		{"RTAX_ADVMSS", Const, 0, ""},
		{"RTAX_AUTHOR", Const, 0, ""},
		{"RTAX_BRD", Const, 0, ""},
		{"RTAX_CWND", Const, 0, ""},
		{"RTAX_DST", Const, 0, ""},
		{"RTAX_FEATURES", Const, 0, ""},
		{"RTAX_FEATURE_ALLFRAG", Const, 0, ""},
		{"RTAX_FEATURE_ECN", Const, 0, ""},
		{"RTAX_FEATURE_SACK", Const, 0, ""},
		{"RTAX_FEATURE_TIMESTAMP", Const, 0, ""},
		{"RTAX_GATEWAY", Const, 0, ""},
		{"RTAX_GENMASK", Const, 0, ""},
		{"RTAX_HOPLIMIT", Const, 0, ""},
		{"RTAX_IFA", Const, 0, ""},
		{"RTAX_IFP", Const, 0, ""},
		{"RTAX_INITCWND", Const, 0, ""},
		{"RTAX_INITRWND", Const, 0, ""},
		{"RTAX_LABEL", Const, 1, ""},
		{"RTAX_LOCK", Const, 0, ""},
		{"RTAX_MAX", Const, 0, ""},
		{"RTAX_MTU", Const, 0, ""},
		{"RTAX_NETMASK", Const, 0, ""},
		{"RTAX_REORDERING", Const, 0, ""},
		{"RTAX_RTO_MIN", Const, 0, ""},
		{"RTAX_RTT", Const, 0, ""},
		{"RTAX_RTTVAR", Const, 0, ""},
		{"RTAX_SRC", Const, 1, ""},
		{"RTAX_SRCMASK", Const, 1, ""},
		{"RTAX_SSTHRESH", Const, 0, ""},
		{"RTAX_TAG", Const, 1, ""},
		{"RTAX_UNSPEC", Const, 0, ""},
		{"RTAX_WINDOW", Const, 0, ""},
		{"RTA_ALIGNTO", Const, 0, ""},
		{"RTA_AUTHOR", Const, 0, ""},
		{"RTA_BRD", Const, 0, ""},
		{"RTA_CACHEINFO", Const, 0, ""},
		{"RTA_DST", Const, 0, ""},
		{"RTA_FLOW", Const, 0, ""},
		{"RTA_GATEWAY", Const, 0, ""},
		{"RTA_GENMASK", Const, 0, ""},
		{"RTA_IFA", Const, 0, ""},
		{"RTA_IFP", Const, 0, ""},
		{"RTA_IIF", Const, 0, ""},
		{"RTA_LABEL", Const, 1, ""},
		{"RTA_MAX", Const, 0, ""},
		{"RTA_METRICS", Const, 0, ""},
		{"RTA_MULTIPATH", Const, 0, ""},
		{"RTA_NETMASK", Const, 0, ""},
		{"RTA_OIF", Const, 0, ""},
		{"RTA_PREFSRC", Const, 0, ""},
		{"RTA_PRIORITY", Const, 0, ""},
		{"RTA_SRC", Const, 0, ""},
		{"RTA_SRCMASK", Const, 1, ""},
		{"RTA_TABLE", Const, 0, ""},
		{"RTA_TAG", Const, 1, ""},
		{"RTA_UNSPEC", Const, 0, ""},
		{"RTCF_DIRECTSRC", Const, 0, ""},
		{"RTCF_DOREDIRECT", Const, 0, ""},
		{"RTCF_LOG", Const, 0, ""},
		{"RTCF_MASQ", Const, 0, ""},
		{"RTCF_NAT", Const, 0, ""},
		{"RTCF_VALVE", Const, 0, ""},
		{"RTF_ADDRCLASSMASK", Const, 0, ""},
		{"RTF_ADDRCONF", Const, 0, ""},
		{"RTF_ALLONLINK", Const, 0, ""},
		{"RTF_ANNOUNCE", Const, 1, ""},
		{"RTF_BLACKHOLE", Const, 0, ""},
		{"RTF_BROADCAST", Const, 0, ""},
		{"RTF_CACHE", Const, 0, ""},
		{"RTF_CLONED", Const, 1, ""},
		{"RTF_CLONING", Const, 0, ""},
		{"RTF_CONDEMNED", Const, 0, ""},
		{"RTF_DEFAULT", Const, 0, ""},
		{"RTF_DELCLONE", Const, 0, ""},
		{"RTF_DONE", Const, 0, ""},
		{"RTF_DYNAMIC", Const, 0, ""},
		{"RTF_FLOW", Const, 0, ""},
		{"RTF_FMASK", Const, 0, ""},
		{"RTF_GATEWAY", Const, 0, ""},
		{"RTF_GWFLAG_COMPAT", Const, 3, ""},
		{"RTF_HOST", Const, 0, ""},
		{"RTF_IFREF", Const, 0, ""},
		{"RTF_IFSCOPE", Const, 0, ""},
		{"RTF_INTERFACE", Const, 0, ""},
		{"RTF_IRTT", Const, 0, ""},
		{"RTF_LINKRT", Const, 0, ""},
		{"RTF_LLDATA", Const, 0, ""},
		{"RTF_LLINFO", Const, 0, ""},
		{"RTF_LOCAL", Const, 0, ""},
		{"RTF_MASK", Const, 1, ""},
		{"RTF_MODIFIED", Const, 0, ""},
		{"RTF_MPATH", Const, 1, ""},
		{"RTF_MPLS", Const, 1, ""},
		{"RTF_MSS", Const, 0, ""},
		{"RTF_MTU", Const, 0, ""},
		{"RTF_MULTICAST", Const, 0, ""},
		{"RTF_NAT", Const, 0, ""},
		{"RTF_NOFORWARD", Const, 0, ""},
		{"RTF_NONEXTHOP", Const, 0, ""},
		{"RTF_NOPMTUDISC", Const, 0, ""},
		{"RTF_PERMANENT_ARP", Const, 1, ""},
		{"RTF_PINNED", Const, 0, ""},
		{"RTF_POLICY", Const, 0, ""},
		{"RTF_PRCLONING", Const, 0, ""},
		{"RTF_PROTO1", Const, 0, ""},
		{"RTF_PROTO2", Const, 0, ""},
		{"RTF_PROTO3", Const, 0, ""},
		{"RTF_PROXY", Const, 16, ""},
		{"RTF_REINSTATE", Const, 0, ""},
		{"RTF_REJECT", Const, 0, ""},
		{"RTF_RNH_LOCKED", Const, 0, ""},
		{"RTF_ROUTER", Const, 16, ""},
		{"RTF_SOURCE", Const, 1, ""},
		{"RTF_SRC", Const, 1, ""},
		{"RTF_STATIC", Const, 0, ""},
		{"RTF_STICKY", Const, 0, ""},
		{"RTF_THROW", Const, 0, ""},
		{"RTF_TUNNEL", Const, 1, ""},
		{"RTF_UP", Const, 0, ""},
		{"RTF_USETRAILERS", Const, 1, ""},
		{"RTF_WASCLONED", Const, 0, ""},
		{"RTF_WINDOW", Const, 0, ""},
		{"RTF_XRESOLVE", Const, 0, ""},
		{"RTM_ADD", Const, 0, ""},
		{"RTM_BASE", Const, 0, ""},
		{"RTM_CHANGE", Const, 0, ""},
		{"RTM_CHGADDR", Const, 1, ""},
		{"RTM_DELACTION", Const, 0, ""},
		{"RTM_DELADDR", Const, 0, ""},
		{"RTM_DELADDRLABEL", Const, 0, ""},
		{"RTM_DELETE", Const, 0, ""},
		{"RTM_DELLINK", Const, 0, ""},
		{"RTM_DELMADDR", Const, 0, ""},
		{"RTM_DELNEIGH", Const, 0, ""},
		{"RTM_DELQDISC", Const, 0, ""},
		{"RTM_DELROUTE", Const, 0, ""},
		{"RTM_DELRULE", Const, 0, ""},
		{"RTM_DELTCLASS", Const, 0, ""},
		{"RTM_DELTFILTER", Const, 0, ""},
		{"RTM_DESYNC", Const, 1, ""},
		{"RTM_F_CLONED", Const, 0, ""},
		{"RTM_F_EQUALIZE", Const, 0, ""},
		{"RTM_F_NOTIFY", Const, 0, ""},
		{"RTM_F_PREFIX", Const, 0, ""},
		{"RTM_GET", Const, 0, ""},
		{"RTM_GET2", Const, 0, ""},
		{"RTM_GETACTION", Const, 0, ""},
		{"RTM_GETADDR", Const, 0, ""},
		{"RTM_GETADDRLABEL", Const, 0, ""},
		{"RTM_GETANYCAST", Const, 0, ""},
		{"RTM_GETDCB", Const, 0, ""},
		{"RTM_GETLINK", Const, 0, ""},
		{"RTM_GETMULTICAST", Const, 0, ""},
		{"RTM_GETNEIGH", Const, 0, ""},
		{"RTM_GETNEIGHTBL", Const, 0, ""},
		{"RTM_GETQDISC", Const, 0, ""},
		{"RTM_GETROUTE", Const, 0, ""},
		{"RTM_GETRULE", Const, 0, ""},
		{"RTM_GETTCLASS", Const, 0, ""},
		{"RTM_GETTFILTER", Const, 0, ""},
		{"RTM_IEEE80211", Const, 0, ""},
		{"RTM_IFANNOUNCE", Const, 0, ""},
		{"RTM_IFINFO", Const, 0, ""},
		{"RTM_IFINFO2", Const, 0, ""},
		{"RTM_LLINFO_UPD", Const, 1, ""},
		{"RTM_LOCK", Const, 0, ""},
		{"RTM_LOSING", Const, 0, ""},
		{"RTM_MAX", Const, 0, ""},
		{"RTM_MAXSIZE", Const, 1, ""},
		{"RTM_MISS", Const, 0, ""},
		{"RTM_NEWACTION", Const, 0, ""},
		{"RTM_NEWADDR", Const, 0, ""},
		{"RTM_NEWADDRLABEL", Const, 0, ""},
		{"RTM_NEWLINK", Const, 0, ""},
		{"RTM_NEWMADDR", Const, 0, ""},
		{"RTM_NEWMADDR2", Const, 0, ""},
		{"RTM_NEWNDUSEROPT", Const, 0, ""},
		{"RTM_NEWNEIGH", Const, 0, ""},
		{"RTM_NEWNEIGHTBL", Const, 0, ""},
		{"RTM_NEWPREFIX", Const, 0, ""},
		{"RTM_NEWQDISC", Const, 0, ""},
		{"RTM_NEWROUTE", Const, 0, ""},
		{"RTM_NEWRULE", Const, 0, ""},
		{"RTM_NEWTCLASS", Const, 0, ""},
		{"RTM_NEWTFILTER", Const, 0, ""},
		{"RTM_NR_FAMILIES", Const, 0, ""},
		{"RTM_NR_MSGTYPES", Const, 0, ""},
		{"RTM_OIFINFO", Const, 1, ""},
		{"RTM_OLDADD", Const, 0, ""},
		{"RTM_OLDDEL", Const, 0, ""},
		{"RTM_OOIFINFO", Const, 1, ""},
		{"RTM_REDIRECT", Const, 0, ""},
		{"RTM_RESOLVE", Const, 0, ""},
		{"RTM_RTTUNIT", Const, 0, ""},
		{"RTM_SETDCB", Const, 0, ""},
		{"RTM_SETGATE", Const, 1, ""},
		{"RTM_SETLINK", Const, 0, ""},
		{"RTM_SETNEIGHTBL", Const, 0, ""},
		{"RTM_VERSION", Const, 0, ""},
		{"RTNH_ALIGNTO", Const, 0, ""},
		{"RTNH_F_DEAD", Const, 0, ""},
		{"RTNH_F_ONLINK", Const, 0, ""},
		{"RTNH_F_PERVASIVE", Const, 0, ""},
		{"RTNLGRP_IPV4_IFADDR", Const, 1, ""},
		{"RTNLGRP_IPV4_MROUTE", Const, 1, ""},
		{"RTNLGRP_IPV4_ROUTE", Const, 1, ""},
		{"RTNLGRP_IPV4_RULE", Const, 1, ""},
		{"RTNLGRP_IPV6_IFADDR", Const, 1, ""},
		{"RTNLGRP_IPV6_IFINFO", Const, 1, ""},
		{"RTNLGRP_IPV6_MROUTE", Const, 1, ""},
		{"RTNLGRP_IPV6_PREFIX", Const, 1, ""},
		{"RTNLGRP_IPV6_ROUTE", Const, 1, ""},
		{"RTNLGRP_IPV6_RULE", Const, 1, ""},
		{"RTNLGRP_LINK", Const, 1, ""},
		{"RTNLGRP_ND_USEROPT", Const, 1, ""},
		{"RTNLGRP_NEIGH", Const, 1, ""},
		{"RTNLGRP_NONE", Const, 1, ""},
		{"RTNLGRP_NOTIFY", Const, 1, ""},
		{"RTNLGRP_TC", Const, 1, ""},
		{"RTN_ANYCAST", Const, 0, ""},
		{"RTN_BLACKHOLE", Const, 0, ""},
		{"RTN_BROADCAST", Const, 0, ""},
		{"RTN_LOCAL", Const, 0, ""},
		{"RTN_MAX", Const, 0, ""},
		{"RTN_MULTICAST", Const, 0, ""},
		{"RTN_NAT", Const, 0, ""},
		{"RTN_PROHIBIT", Const, 0, ""},
		{"RTN_THROW", Const, 0, ""},
		{"RTN_UNICAST", Const, 0, ""},
		{"RTN_UNREACHABLE", Const, 0, ""},
		{"RTN_UNSPEC", Const, 0, ""},
		{"RTN_XRESOLVE", Const, 0, ""},
		{"RTPROT_BIRD", Const, 0, ""},
		{"RTPROT_BOOT", Const, 0, ""},
		{"RTPROT_DHCP", Const, 0, ""},
		{"RTPROT_DNROUTED", Const, 0, ""},
		{"RTPROT_GATED", Const, 0, ""},
		{"RTPROT_KERNEL", Const, 0, ""},
		{"RTPROT_MRT", Const, 0, ""},
		{"RTPROT_NTK", Const, 0, ""},
		{"RTPROT_RA", Const, 0, ""},
		{"RTPROT_REDIRECT", Const, 0, ""},
		{"RTPROT_STATIC", Const, 0, ""},
		{"RTPROT_UNSPEC", Const, 0, ""},
		{"RTPROT_XORP", Const, 0, ""},
		{"RTPROT_ZEBRA", Const, 0, ""},
		{"RTV_EXPIRE", Const, 0, ""},
		{"RTV_HOPCOUNT", Const, 0, ""},
		{"RTV_MTU", Const, 0, ""},
		{"RTV_RPIPE", Const, 0, ""},
		{"RTV_RTT", Const, 0, ""},
		{"RTV_RTTVAR", Const, 0, ""},
		{"RTV_SPIPE", Const, 0, ""},
		{"RTV_SSTHRESH", Const, 0, ""},
		{"RTV_WEIGHT", Const, 0, ""},
		{"RT_CACHING_CONTEXT", Const, 1, ""},
		{"RT_CLASS_DEFAULT", Const, 0, ""},
		{"RT_CLASS_LOCAL", Const, 0, ""},
		{"RT_CLASS_MAIN", Const, 0, ""},
		{"RT_CLASS_MAX", Const, 0, ""},
		{"RT_CLASS_UNSPEC", Const, 0, ""},
		{"RT_DEFAULT_FIB", Const, 1, ""},
		{"RT_NORTREF", Const, 1, ""},
		{"RT_SCOPE_HOST", Const, 0, ""},
		{"RT_SCOPE_LINK", Const, 0, ""},
		{"RT_SCOPE_NOWHERE", Const, 0, ""},
		{"RT_SCOPE_SITE", Const, 0, ""},
		{"RT_SCOPE_UNIVERSE", Const, 0, ""},
		{"RT_TABLEID_MAX", Const, 1, ""},
		{"RT_TABLE_COMPAT", Const, 0, ""},
		{"RT_TABLE_DEFAULT", Const, 0, ""},
		{"RT_TABLE_LOCAL", Const, 0, ""},
		{"RT_TABLE_MAIN", Const, 0, ""},
		{"RT_TABLE_MAX", Const, 0, ""},
		{"RT_TABLE_UNSPEC", Const, 0, ""},
		{"RUSAGE_CHILDREN", Const, 0, ""},
		{"RUSAGE_SELF", Const, 0, ""},
		{"RUSAGE_THREAD", Const, 0, ""},
		{"Radvisory_t", Type, 0, ""},
		{"Radvisory_t.Count", Field, 0, ""},
		{"Radvisory_t.Offset", Field, 0, ""},
		{"Radvisory_t.Pad_cgo_0", Field, 0, ""},
		{"RawConn", Type, 9, ""},
		{"RawSockaddr", Type, 0, ""},
		{"RawSockaddr.Data", Field, 0, ""},
		{"RawSockaddr.Family", Field, 0, ""},
		{"RawSockaddr.Len", Field, 0, ""},
		{"RawSockaddrAny", Type, 0, ""},
		{"RawSockaddrAny.Addr", Field, 0, ""},
		{"RawSockaddrAny.Pad", Field, 0, ""},
		{"RawSockaddrDatalink", Type, 0, ""},
		{"RawSockaddrDatalink.Alen", Field, 0, ""},
		{"RawSockaddrDatalink.Data", Field, 0, ""},
		{"RawSockaddrDatalink.Family", Field, 0, ""},
		{"RawSockaddrDatalink.Index", Field, 0, ""},
		{"RawSockaddrDatalink.Len", Field, 0, ""},
		{"RawSockaddrDatalink.Nlen", Field, 0, ""},
		{"RawSockaddrDatalink.Pad_cgo_0", Field, 2, ""},
		{"RawSockaddrDatalink.Slen", Field, 0, ""},
		{"RawSockaddrDatalink.Type", Field, 0, ""},
		{"RawSockaddrInet4", Type, 0, ""},
		{"RawSockaddrInet4.Addr", Field, 0, ""},
		{"RawSockaddrInet4.Family", Field, 0, ""},
		{"RawSockaddrInet4.Len", Field, 0, ""},
		{"RawSockaddrInet4.Port", Field, 0, ""},
		{"RawSockaddrInet4.Zero", Field, 0, ""},
		{"RawSockaddrInet6", Type, 0, ""},
		{"RawSockaddrInet6.Addr", Field, 0, ""},
		{"RawSockaddrInet6.Family", Field, 0, ""},
		{"RawSockaddrInet6.Flowinfo", Field, 0, ""},
		{"RawSockaddrInet6.Len", Field, 0, ""},
		{"RawSockaddrInet6.Port", Field, 0, ""},
		{"RawSockaddrInet6.Scope_id", Field, 0, ""},
		{"RawSockaddrLinklayer", Type, 0, ""},
		{"RawSockaddrLinklayer.Addr", Field, 0, ""},
		{"RawSockaddrLinklayer.Family", Field, 0, ""},
		{"RawSockaddrLinklayer.Halen", Field, 0, ""},
		{"RawSockaddrLinklayer.Hatype", Field, 0, ""},
		{"RawSockaddrLinklayer.Ifindex", Field, 0, ""},
		{"RawSockaddrLinklayer.Pkttype", Field, 0, ""},
		{"RawSockaddrLinklayer.Protocol", Field, 0, ""},
		{"RawSockaddrNetlink", Type, 0, ""},
		{"RawSockaddrNetlink.Family", Field, 0, ""},
		{"RawSockaddrNetlink.Groups", Field, 0, ""},
		{"RawSockaddrNetlink.Pad", Field, 0, ""},
		{"RawSockaddrNetlink.Pid", Field, 0, ""},
		{"RawSockaddrUnix", Type, 0, ""},
		{"RawSockaddrUnix.Family", Field, 0, ""},
		{"RawSockaddrUnix.Len", Field, 0, ""},
		{"RawSockaddrUnix.Pad_cgo_0", Field, 2, ""},
		{"RawSockaddrUnix.Path", Field, 0, ""},
		{"RawSyscall", Func, 0, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"RawSyscall6", Func, 0, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr, a4 uintptr, a5 uintptr, a6 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"Read", Func, 0, "func(fd int, p []byte) (n int, err error)"},
		{"ReadConsole", Func, 1, ""},
		{"ReadDirectoryChanges", Func, 0, ""},
		{"ReadDirent", Func, 0, "func(fd int, buf []byte) (n int, err error)"},
		{"ReadFile", Func, 0, ""},
		{"Readlink", Func, 0, "func(path string, buf []byte) (n int, err error)"},
		{"Reboot", Func, 0, "func(cmd int) (err error)"},
		{"Recvfrom", Func, 0, "func(fd int, p []byte, flags int) (n int, from Sockaddr, err error)"},
		{"Recvmsg", Func, 0, "func(fd int, p []byte, oob []byte, flags int) (n int, oobn int, recvflags int, from Sockaddr, err error)"},
		{"RegCloseKey", Func, 0, ""},
		{"RegEnumKeyEx", Func, 0, ""},
		{"RegOpenKeyEx", Func, 0, ""},
		{"RegQueryInfoKey", Func, 0, ""},
		{"RegQueryValueEx", Func, 0, ""},
		{"RemoveDirectory", Func, 0, ""},
		{"Removexattr", Func, 1, "func(path string, attr string) (err error)"},
		{"Rename", Func, 0, "func(oldpath string, newpath string) (err error)"},
		{"Renameat", Func, 0, "func(olddirfd int, oldpath string, newdirfd int, newpath string) (err error)"},
		{"Revoke", Func, 0, ""},
		{"Rlimit", Type, 0, ""},
		{"Rlimit.Cur", Field, 0, ""},
		{"Rlimit.Max", Field, 0, ""},
		{"Rmdir", Func, 0, "func(path string) error"},
		{"RouteMessage", Type, 0, ""},
		{"RouteMessage.Data", Field, 0, ""},
		{"RouteMessage.Header", Field, 0, ""},
		{"RouteRIB", Func, 0, ""},
		{"RoutingMessage", Type, 14, ""},
		{"RtAttr", Type, 0, ""},
		{"RtAttr.Len", Field, 0, ""},
		{"RtAttr.Type", Field, 0, ""},
		{"RtGenmsg", Type, 0, ""},
		{"RtGenmsg.Family", Field, 0, ""},
		{"RtMetrics", Type, 0, ""},
		{"RtMetrics.Expire", Field, 0, ""},
		{"RtMetrics.Filler", Field, 0, ""},
		{"RtMetrics.Hopcount", Field, 0, ""},
		{"RtMetrics.Locks", Field, 0, ""},
		{"RtMetrics.Mtu", Field, 0, ""},
		{"RtMetrics.Pad", Field, 3, ""},
		{"RtMetrics.Pksent", Field, 0, ""},
		{"RtMetrics.Recvpipe", Field, 0, ""},
		{"RtMetrics.Refcnt", Field, 2, ""},
		{"RtMetrics.Rtt", Field, 0, ""},
		{"RtMetrics.Rttvar", Field, 0, ""},
		{"RtMetrics.Sendpipe", Field, 0, ""},
		{"RtMetrics.Ssthresh", Field, 0, ""},
		{"RtMetrics.Weight", Field, 0, ""},
		{"RtMsg", Type, 0, ""},
		{"RtMsg.Dst_len", Field, 0, ""},
		{"RtMsg.Family", Field, 0, ""},
		{"RtMsg.Flags", Field, 0, ""},
		{"RtMsg.Protocol", Field, 0, ""},
		{"RtMsg.Scope", Field, 0, ""},
		{"RtMsg.Src_len", Field, 0, ""},
		{"RtMsg.Table", Field, 0, ""},
		{"RtMsg.Tos", Field, 0, ""},
		{"RtMsg.Type", Field, 0, ""},
		{"RtMsghdr", Type, 0, ""},
		{"RtMsghdr.Addrs", Field, 0, ""},
		{"RtMsghdr.Errno", Field, 0, ""},
		{"RtMsghdr.Flags", Field, 0, ""},
		{"RtMsghdr.Fmask", Field, 0, ""},
		{"RtMsghdr.Hdrlen", Field, 2, ""},
		{"RtMsghdr.Index", Field, 0, ""},
		{"RtMsghdr.Inits", Field, 0, ""},
		{"RtMsghdr.Mpls", Field, 2, ""},
		{"RtMsghdr.Msglen", Field, 0, ""},
		{"RtMsghdr.Pad_cgo_0", Field, 0, ""},
		{"RtMsghdr.Pad_cgo_1", Field, 2, ""},
		{"RtMsghdr.Pid", Field, 0, ""},
		{"RtMsghdr.Priority", Field, 2, ""},
		{"RtMsghdr.Rmx", Field, 0, ""},
		{"RtMsghdr.Seq", Field, 0, ""},
		{"RtMsghdr.Tableid", Field, 2, ""},
		{"RtMsghdr.Type", Field, 0, ""},
		{"RtMsghdr.Use", Field, 0, ""},
		{"RtMsghdr.Version", Field, 0, ""},
		{"RtNexthop", Type, 0, ""},
		{"RtNexthop.Flags", Field, 0, ""},
		{"RtNexthop.Hops", Field, 0, ""},
		{"RtNexthop.Ifindex", Field, 0, ""},
		{"RtNexthop.Len", Field, 0, ""},
		{"Rusage", Type, 0, ""},
		{"Rusage.CreationTime", Field, 0, ""},
		{"Rusage.ExitTime", Field, 0, ""},
		{"Rusage.Idrss", Field, 0, ""},
		{"Rusage.Inblock", Field, 0, ""},
		{"Rusage.Isrss", Field, 0, ""},
		{"Rusage.Ixrss", Field, 0, ""},
		{"Rusage.KernelTime", Field, 0, ""},
		{"Rusage.Majflt", Field, 0, ""},
		{"Rusage.Maxrss", Field, 0, ""},
		{"Rusage.Minflt", Field, 0, ""},
		{"Rusage.Msgrcv", Field, 0, ""},
		{"Rusage.Msgsnd", Field, 0, ""},
		{"Rusage.Nivcsw", Field, 0, ""},
		{"Rusage.Nsignals", Field, 0, ""},
		{"Rusage.Nswap", Field, 0, ""},
		{"Rusage.Nvcsw", Field, 0, ""},
		{"Rusage.Oublock", Field, 0, ""},
		{"Rusage.Stime", Field, 0, ""},
		{"Rusage.UserTime", Field, 0, ""},
		{"Rusage.Utime", Field, 0, ""},
		{"SCM_BINTIME", Const, 0, ""},
		{"SCM_CREDENTIALS", Const, 0, ""},
		{"SCM_CREDS", Const, 0, ""},
		{"SCM_RIGHTS", Const, 0, ""},
		{"SCM_TIMESTAMP", Const, 0, ""},
		{"SCM_TIMESTAMPING", Const, 0, ""},
		{"SCM_TIMESTAMPNS", Const, 0, ""},
		{"SCM_TIMESTAMP_MONOTONIC", Const, 0, ""},
		{"SHUT_RD", Const, 0, ""},
		{"SHUT_RDWR", Const, 0, ""},
		{"SHUT_WR", Const, 0, ""},
		{"SID", Type, 0, ""},
		{"SIDAndAttributes", Type, 0, ""},
		{"SIDAndAttributes.Attributes", Field, 0, ""},
		{"SIDAndAttributes.Sid", Field, 0, ""},
		{"SIGABRT", Const, 0, ""},
		{"SIGALRM", Const, 0, ""},
		{"SIGBUS", Const, 0, ""},
		{"SIGCHLD", Const, 0, ""},
		{"SIGCLD", Const, 0, ""},
		{"SIGCONT", Const, 0, ""},
		{"SIGEMT", Const, 0, ""},
		{"SIGFPE", Const, 0, ""},
		{"SIGHUP", Const, 0, ""},
		{"SIGILL", Const, 0, ""},
		{"SIGINFO", Const, 0, ""},
		{"SIGINT", Const, 0, ""},
		{"SIGIO", Const, 0, ""},
		{"SIGIOT", Const, 0, ""},
		{"SIGKILL", Const, 0, ""},
		{"SIGLIBRT", Const, 1, ""},
		{"SIGLWP", Const, 0, ""},
		{"SIGPIPE", Const, 0, ""},
		{"SIGPOLL", Const, 0, ""},
		{"SIGPROF", Const, 0, ""},
		{"SIGPWR", Const, 0, ""},
		{"SIGQUIT", Const, 0, ""},
		{"SIGSEGV", Const, 0, ""},
		{"SIGSTKFLT", Const, 0, ""},
		{"SIGSTOP", Const, 0, ""},
		{"SIGSYS", Const, 0, ""},
		{"SIGTERM", Const, 0, ""},
		{"SIGTHR", Const, 0, ""},
		{"SIGTRAP", Const, 0, ""},
		{"SIGTSTP", Const, 0, ""},
		{"SIGTTIN", Const, 0, ""},
		{"SIGTTOU", Const, 0, ""},
		{"SIGUNUSED", Const, 0, ""},
		{"SIGURG", Const, 0, ""},
		{"SIGUSR1", Const, 0, ""},
		{"SIGUSR2", Const, 0, ""},
		{"SIGVTALRM", Const, 0, ""},
		{"SIGWINCH", Const, 0, ""},
		{"SIGXCPU", Const, 0, ""},
		{"SIGXFSZ", Const, 0, ""},
		{"SIOCADDDLCI", Const, 0, ""},
		{"SIOCADDMULTI", Const, 0, ""},
		{"SIOCADDRT", Const, 0, ""},
		{"SIOCAIFADDR", Const, 0, ""},
		{"SIOCAIFGROUP", Const, 0, ""},
		{"SIOCALIFADDR", Const, 0, ""},
		{"SIOCARPIPLL", Const, 0, ""},
		{"SIOCATMARK", Const, 0, ""},
		{"SIOCAUTOADDR", Const, 0, ""},
		{"SIOCAUTONETMASK", Const, 0, ""},
		{"SIOCBRDGADD", Const, 1, ""},
		{"SIOCBRDGADDS", Const, 1, ""},
		{"SIOCBRDGARL", Const, 1, ""},
		{"SIOCBRDGDADDR", Const, 1, ""},
		{"SIOCBRDGDEL", Const, 1, ""},
		{"SIOCBRDGDELS", Const, 1, ""},
		{"SIOCBRDGFLUSH", Const, 1, ""},
		{"SIOCBRDGFRL", Const, 1, ""},
		{"SIOCBRDGGCACHE", Const, 1, ""},
		{"SIOCBRDGGFD", Const, 1, ""},
		{"SIOCBRDGGHT", Const, 1, ""},
		{"SIOCBRDGGIFFLGS", Const, 1, ""},
		{"SIOCBRDGGMA", Const, 1, ""},
		{"SIOCBRDGGPARAM", Const, 1, ""},
		{"SIOCBRDGGPRI", Const, 1, ""},
		{"SIOCBRDGGRL", Const, 1, ""},
		{"SIOCBRDGGSIFS", Const, 1, ""},
		{"SIOCBRDGGTO", Const, 1, ""},
		{"SIOCBRDGIFS", Const, 1, ""},
		{"SIOCBRDGRTS", Const, 1, ""},
		{"SIOCBRDGSADDR", Const, 1, ""},
		{"SIOCBRDGSCACHE", Const, 1, ""},
		{"SIOCBRDGSFD", Const, 1, ""},
		{"SIOCBRDGSHT", Const, 1, ""},
		{"SIOCBRDGSIFCOST", Const, 1, ""},
		{"SIOCBRDGSIFFLGS", Const, 1, ""},
		{"SIOCBRDGSIFPRIO", Const, 1, ""},
		{"SIOCBRDGSMA", Const, 1, ""},
		{"SIOCBRDGSPRI", Const, 1, ""},
		{"SIOCBRDGSPROTO", Const, 1, ""},
		{"SIOCBRDGSTO", Const, 1, ""},
		{"SIOCBRDGSTXHC", Const, 1, ""},
		{"SIOCDARP", Const, 0, ""},
		{"SIOCDELDLCI", Const, 0, ""},
		{"SIOCDELMULTI", Const, 0, ""},
		{"SIOCDELRT", Const, 0, ""},
		{"SIOCDEVPRIVATE", Const, 0, ""},
		{"SIOCDIFADDR", Const, 0, ""},
		{"SIOCDIFGROUP", Const, 0, ""},
		{"SIOCDIFPHYADDR", Const, 0, ""},
		{"SIOCDLIFADDR", Const, 0, ""},
		{"SIOCDRARP", Const, 0, ""},
		{"SIOCGARP", Const, 0, ""},
		{"SIOCGDRVSPEC", Const, 0, ""},
		{"SIOCGETKALIVE", Const, 1, ""},
		{"SIOCGETLABEL", Const, 1, ""},
		{"SIOCGETPFLOW", Const, 1, ""},
		{"SIOCGETPFSYNC", Const, 1, ""},
		{"SIOCGETSGCNT", Const, 0, ""},
		{"SIOCGETVIFCNT", Const, 0, ""},
		{"SIOCGETVLAN", Const, 0, ""},
		{"SIOCGHIWAT", Const, 0, ""},
		{"SIOCGIFADDR", Const, 0, ""},
		{"SIOCGIFADDRPREF", Const, 1, ""},
		{"SIOCGIFALIAS", Const, 1, ""},
		{"SIOCGIFALTMTU", Const, 0, ""},
		{"SIOCGIFASYNCMAP", Const, 0, ""},
		{"SIOCGIFBOND", Const, 0, ""},
		{"SIOCGIFBR", Const, 0, ""},
		{"SIOCGIFBRDADDR", Const, 0, ""},
		{"SIOCGIFCAP", Const, 0, ""},
		{"SIOCGIFCONF", Const, 0, ""},
		{"SIOCGIFCOUNT", Const, 0, ""},
		{"SIOCGIFDATA", Const, 1, ""},
		{"SIOCGIFDESCR", Const, 0, ""},
		{"SIOCGIFDEVMTU", Const, 0, ""},
		{"SIOCGIFDLT", Const, 1, ""},
		{"SIOCGIFDSTADDR", Const, 0, ""},
		{"SIOCGIFENCAP", Const, 0, ""},
		{"SIOCGIFFIB", Const, 1, ""},
		{"SIOCGIFFLAGS", Const, 0, ""},
		{"SIOCGIFGATTR", Const, 1, ""},
		{"SIOCGIFGENERIC", Const, 0, ""},
		{"SIOCGIFGMEMB", Const, 0, ""},
		{"SIOCGIFGROUP", Const, 0, ""},
		{"SIOCGIFHARDMTU", Const, 3, ""},
		{"SIOCGIFHWADDR", Const, 0, ""},
		{"SIOCGIFINDEX", Const, 0, ""},
		{"SIOCGIFKPI", Const, 0, ""},
		{"SIOCGIFMAC", Const, 0, ""},
		{"SIOCGIFMAP", Const, 0, ""},
		{"SIOCGIFMEDIA", Const, 0, ""},
		{"SIOCGIFMEM", Const, 0, ""},
		{"SIOCGIFMETRIC", Const, 0, ""},
		{"SIOCGIFMTU", Const, 0, ""},
		{"SIOCGIFNAME", Const, 0, ""},
		{"SIOCGIFNETMASK", Const, 0, ""},
		{"SIOCGIFPDSTADDR", Const, 0, ""},
		{"SIOCGIFPFLAGS", Const, 0, ""},
		{"SIOCGIFPHYS", Const, 0, ""},
		{"SIOCGIFPRIORITY", Const, 1, ""},
		{"SIOCGIFPSRCADDR", Const, 0, ""},
		{"SIOCGIFRDOMAIN", Const, 1, ""},
		{"SIOCGIFRTLABEL", Const, 1, ""},
		{"SIOCGIFSLAVE", Const, 0, ""},
		{"SIOCGIFSTATUS", Const, 0, ""},
		{"SIOCGIFTIMESLOT", Const, 1, ""},
		{"SIOCGIFTXQLEN", Const, 0, ""},
		{"SIOCGIFVLAN", Const, 0, ""},
		{"SIOCGIFWAKEFLAGS", Const, 0, ""},
		{"SIOCGIFXFLAGS", Const, 1, ""},
		{"SIOCGLIFADDR", Const, 0, ""},
		{"SIOCGLIFPHYADDR", Const, 0, ""},
		{"SIOCGLIFPHYRTABLE", Const, 1, ""},
		{"SIOCGLIFPHYTTL", Const, 3, ""},
		{"SIOCGLINKSTR", Const, 1, ""},
		{"SIOCGLOWAT", Const, 0, ""},
		{"SIOCGPGRP", Const, 0, ""},
		{"SIOCGPRIVATE_0", Const, 0, ""},
		{"SIOCGPRIVATE_1", Const, 0, ""},
		{"SIOCGRARP", Const, 0, ""},
		{"SIOCGSPPPPARAMS", Const, 3, ""},
		{"SIOCGSTAMP", Const, 0, ""},
		{"SIOCGSTAMPNS", Const, 0, ""},
		{"SIOCGVH", Const, 1, ""},
		{"SIOCGVNETID", Const, 3, ""},
		{"SIOCIFCREATE", Const, 0, ""},
		{"SIOCIFCREATE2", Const, 0, ""},
		{"SIOCIFDESTROY", Const, 0, ""},
		{"SIOCIFGCLONERS", Const, 0, ""},
		{"SIOCINITIFADDR", Const, 1, ""},
		{"SIOCPROTOPRIVATE", Const, 0, ""},
		{"SIOCRSLVMULTI", Const, 0, ""},
		{"SIOCRTMSG", Const, 0, ""},
		{"SIOCSARP", Const, 0, ""},
		{"SIOCSDRVSPEC", Const, 0, ""},
		{"SIOCSETKALIVE", Const, 1, ""},
		{"SIOCSETLABEL", Const, 1, ""},
		{"SIOCSETPFLOW", Const, 1, ""},
		{"SIOCSETPFSYNC", Const, 1, ""},
		{"SIOCSETVLAN", Const, 0, ""},
		{"SIOCSHIWAT", Const, 0, ""},
		{"SIOCSIFADDR", Const, 0, ""},
		{"SIOCSIFADDRPREF", Const, 1, ""},
		{"SIOCSIFALTMTU", Const, 0, ""},
		{"SIOCSIFASYNCMAP", Const, 0, ""},
		{"SIOCSIFBOND", Const, 0, ""},
		{"SIOCSIFBR", Const, 0, ""},
		{"SIOCSIFBRDADDR", Const, 0, ""},
		{"SIOCSIFCAP", Const, 0, ""},
		{"SIOCSIFDESCR", Const, 0, ""},
		{"SIOCSIFDSTADDR", Const, 0, ""},
		{"SIOCSIFENCAP", Const, 0, ""},
		{"SIOCSIFFIB", Const, 1, ""},
		{"SIOCSIFFLAGS", Const, 0, ""},
		{"SIOCSIFGATTR", Const, 1, ""},
		{"SIOCSIFGENERIC", Const, 0, ""},
		{"SIOCSIFHWADDR", Const, 0, ""},
		{"SIOCSIFHWBROADCAST", Const, 0, ""},
		{"SIOCSIFKPI", Const, 0, ""},
		{"SIOCSIFLINK", Const, 0, ""},
		{"SIOCSIFLLADDR", Const, 0, ""},
		{"SIOCSIFMAC", Const, 0, ""},
		{"SIOCSIFMAP", Const, 0, ""},
		{"SIOCSIFMEDIA", Const, 0, ""},
		{"SIOCSIFMEM", Const, 0, ""},
		{"SIOCSIFMETRIC", Const, 0, ""},
		{"SIOCSIFMTU", Const, 0, ""},
		{"SIOCSIFNAME", Const, 0, ""},
		{"SIOCSIFNETMASK", Const, 0, ""},
		{"SIOCSIFPFLAGS", Const, 0, ""},
		{"SIOCSIFPHYADDR", Const, 0, ""},
		{"SIOCSIFPHYS", Const, 0, ""},
		{"SIOCSIFPRIORITY", Const, 1, ""},
		{"SIOCSIFRDOMAIN", Const, 1, ""},
		{"SIOCSIFRTLABEL", Const, 1, ""},
		{"SIOCSIFRVNET", Const, 0, ""},
		{"SIOCSIFSLAVE", Const, 0, ""},
		{"SIOCSIFTIMESLOT", Const, 1, ""},
		{"SIOCSIFTXQLEN", Const, 0, ""},
		{"SIOCSIFVLAN", Const, 0, ""},
		{"SIOCSIFVNET", Const, 0, ""},
		{"SIOCSIFXFLAGS", Const, 1, ""},
		{"SIOCSLIFPHYADDR", Const, 0, ""},
		{"SIOCSLIFPHYRTABLE", Const, 1, ""},
		{"SIOCSLIFPHYTTL", Const, 3, ""},
		{"SIOCSLINKSTR", Const, 1, ""},
		{"SIOCSLOWAT", Const, 0, ""},
		{"SIOCSPGRP", Const, 0, ""},
		{"SIOCSRARP", Const, 0, ""},
		{"SIOCSSPPPPARAMS", Const, 3, ""},
		{"SIOCSVH", Const, 1, ""},
		{"SIOCSVNETID", Const, 3, ""},
		{"SIOCZIFDATA", Const, 1, ""},
		{"SIO_GET_EXTENSION_FUNCTION_POINTER", Const, 1, ""},
		{"SIO_GET_INTERFACE_LIST", Const, 0, ""},
		{"SIO_KEEPALIVE_VALS", Const, 3, ""},
		{"SIO_UDP_CONNRESET", Const, 4, ""},
		{"SOCK_CLOEXEC", Const, 0, ""},
		{"SOCK_DCCP", Const, 0, ""},
		{"SOCK_DGRAM", Const, 0, ""},
		{"SOCK_FLAGS_MASK", Const, 1, ""},
		{"SOCK_MAXADDRLEN", Const, 0, ""},
		{"SOCK_NONBLOCK", Const, 0, ""},
		{"SOCK_NOSIGPIPE", Const, 1, ""},
		{"SOCK_PACKET", Const, 0, ""},
		{"SOCK_RAW", Const, 0, ""},
		{"SOCK_RDM", Const, 0, ""},
		{"SOCK_SEQPACKET", Const, 0, ""},
		{"SOCK_STREAM", Const, 0, ""},
		{"SOL_AAL", Const, 0, ""},
		{"SOL_ATM", Const, 0, ""},
		{"SOL_DECNET", Const, 0, ""},
		{"SOL_ICMPV6", Const, 0, ""},
		{"SOL_IP", Const, 0, ""},
		{"SOL_IPV6", Const, 0, ""},
		{"SOL_IRDA", Const, 0, ""},
		{"SOL_PACKET", Const, 0, ""},
		{"SOL_RAW", Const, 0, ""},
		{"SOL_SOCKET", Const, 0, ""},
		{"SOL_TCP", Const, 0, ""},
		{"SOL_X25", Const, 0, ""},
		{"SOMAXCONN", Const, 0, ""},
		{"SO_ACCEPTCONN", Const, 0, ""},
		{"SO_ACCEPTFILTER", Const, 0, ""},
		{"SO_ATTACH_FILTER", Const, 0, ""},
		{"SO_BINDANY", Const, 1, ""},
		{"SO_BINDTODEVICE", Const, 0, ""},
		{"SO_BINTIME", Const, 0, ""},
		{"SO_BROADCAST", Const, 0, ""},
		{"SO_BSDCOMPAT", Const, 0, ""},
		{"SO_DEBUG", Const, 0, ""},
		{"SO_DETACH_FILTER", Const, 0, ""},
		{"SO_DOMAIN", Const, 0, ""},
		{"SO_DONTROUTE", Const, 0, ""},
		{"SO_DONTTRUNC", Const, 0, ""},
		{"SO_ERROR", Const, 0, ""},
		{"SO_KEEPALIVE", Const, 0, ""},
		{"SO_LABEL", Const, 0, ""},
		{"SO_LINGER", Const, 0, ""},
		{"SO_LINGER_SEC", Const, 0, ""},
		{"SO_LISTENINCQLEN", Const, 0, ""},
		{"SO_LISTENQLEN", Const, 0, ""},
		{"SO_LISTENQLIMIT", Const, 0, ""},
		{"SO_MARK", Const, 0, ""},
		{"SO_NETPROC", Const, 1, ""},
		{"SO_NKE", Const, 0, ""},
		{"SO_NOADDRERR", Const, 0, ""},
		{"SO_NOHEADER", Const, 1, ""},
		{"SO_NOSIGPIPE", Const, 0, ""},
		{"SO_NOTIFYCONFLICT", Const, 0, ""},
		{"SO_NO_CHECK", Const, 0, ""},
		{"SO_NO_DDP", Const, 0, ""},
		{"SO_NO_OFFLOAD", Const, 0, ""},
		{"SO_NP_EXTENSIONS", Const, 0, ""},
		{"SO_NREAD", Const, 0, ""},
		{"SO_NUMRCVPKT", Const, 16, ""},
		{"SO_NWRITE", Const, 0, ""},
		{"SO_OOBINLINE", Const, 0, ""},
		{"SO_OVERFLOWED", Const, 1, ""},
		{"SO_PASSCRED", Const, 0, ""},
		{"SO_PASSSEC", Const, 0, ""},
		{"SO_PEERCRED", Const, 0, ""},
		{"SO_PEERLABEL", Const, 0, ""},
		{"SO_PEERNAME", Const, 0, ""},
		{"SO_PEERSEC", Const, 0, ""},
		{"SO_PRIORITY", Const, 0, ""},
		{"SO_PROTOCOL", Const, 0, ""},
		{"SO_PROTOTYPE", Const, 1, ""},
		{"SO_RANDOMPORT", Const, 0, ""},
		{"SO_RCVBUF", Const, 0, ""},
		{"SO_RCVBUFFORCE", Const, 0, ""},
		{"SO_RCVLOWAT", Const, 0, ""},
		{"SO_RCVTIMEO", Const, 0, ""},
		{"SO_RESTRICTIONS", Const, 0, ""},
		{"SO_RESTRICT_DENYIN", Const, 0, ""},
		{"SO_RESTRICT_DENYOUT", Const, 0, ""},
		{"SO_RESTRICT_DENYSET", Const, 0, ""},
		{"SO_REUSEADDR", Const, 0, ""},
		{"SO_REUSEPORT", Const, 0, ""},
		{"SO_REUSESHAREUID", Const, 0, ""},
		{"SO_RTABLE", Const, 1, ""},
		{"SO_RXQ_OVFL", Const, 0, ""},
		{"SO_SECURITY_AUTHENTICATION", Const, 0, ""},
		{"SO_SECURITY_ENCRYPTION_NETWORK", Const, 0, ""},
		{"SO_SECURITY_ENCRYPTION_TRANSPORT", Const, 0, ""},
		{"SO_SETFIB", Const, 0, ""},
		{"SO_SNDBUF", Const, 0, ""},
		{"SO_SNDBUFFORCE", Const, 0, ""},
		{"SO_SNDLOWAT", Const, 0, ""},
		{"SO_SNDTIMEO", Const, 0, ""},
		{"SO_SPLICE", Const, 1, ""},
		{"SO_TIMESTAMP", Const, 0, ""},
		{"SO_TIMESTAMPING", Const, 0, ""},
		{"SO_TIMESTAMPNS", Const, 0, ""},
		{"SO_TIMESTAMP_MONOTONIC", Const, 0, ""},
		{"SO_TYPE", Const, 0, ""},
		{"SO_UPCALLCLOSEWAIT", Const, 0, ""},
		{"SO_UPDATE_ACCEPT_CONTEXT", Const, 0, ""},
		{"SO_UPDATE_CONNECT_CONTEXT", Const, 1, ""},
		{"SO_USELOOPBACK", Const, 0, ""},
		{"SO_USER_COOKIE", Const, 1, ""},
		{"SO_VENDOR", Const, 3, ""},
		{"SO_WANTMORE", Const, 0, ""},
		{"SO_WANTOOBFLAG", Const, 0, ""},
		{"SSLExtraCertChainPolicyPara", Type, 0, ""},
		{"SSLExtraCertChainPolicyPara.AuthType", Field, 0, ""},
		{"SSLExtraCertChainPolicyPara.Checks", Field, 0, ""},
		{"SSLExtraCertChainPolicyPara.ServerName", Field, 0, ""},
		{"SSLExtraCertChainPolicyPara.Size", Field, 0, ""},
		{"STANDARD_RIGHTS_ALL", Const, 0, ""},
		{"STANDARD_RIGHTS_EXECUTE", Const, 0, ""},
		{"STANDARD_RIGHTS_READ", Const, 0, ""},
		{"STANDARD_RIGHTS_REQUIRED", Const, 0, ""},
		{"STANDARD_RIGHTS_WRITE", Const, 0, ""},
		{"STARTF_USESHOWWINDOW", Const, 0, ""},
		{"STARTF_USESTDHANDLES", Const, 0, ""},
		{"STD_ERROR_HANDLE", Const, 0, ""},
		{"STD_INPUT_HANDLE", Const, 0, ""},
		{"STD_OUTPUT_HANDLE", Const, 0, ""},
		{"SUBLANG_ENGLISH_US", Const, 0, ""},
		{"SW_FORCEMINIMIZE", Const, 0, ""},
		{"SW_HIDE", Const, 0, ""},
		{"SW_MAXIMIZE", Const, 0, ""},
		{"SW_MINIMIZE", Const, 0, ""},
		{"SW_NORMAL", Const, 0, ""},
		{"SW_RESTORE", Const, 0, ""},
		{"SW_SHOW", Const, 0, ""},
		{"SW_SHOWDEFAULT", Const, 0, ""},
		{"SW_SHOWMAXIMIZED", Const, 0, ""},
		{"SW_SHOWMINIMIZED", Const, 0, ""},
		{"SW_SHOWMINNOACTIVE", Const, 0, ""},
		{"SW_SHOWNA", Const, 0, ""},
		{"SW_SHOWNOACTIVATE", Const, 0, ""},
		{"SW_SHOWNORMAL", Const, 0, ""},
		{"SYMBOLIC_LINK_FLAG_DIRECTORY", Const, 4, ""},
		{"SYNCHRONIZE", Const, 0, ""},
		{"SYSCTL_VERSION", Const, 1, ""},
		{"SYSCTL_VERS_0", Const, 1, ""},
		{"SYSCTL_VERS_1", Const, 1, ""},
		{"SYSCTL_VERS_MASK", Const, 1, ""},
		{"SYS_ABORT2", Const, 0, ""},
		{"SYS_ACCEPT", Const, 0, ""},
		{"SYS_ACCEPT4", Const, 0, ""},
		{"SYS_ACCEPT_NOCANCEL", Const, 0, ""},
		{"SYS_ACCESS", Const, 0, ""},
		{"SYS_ACCESS_EXTENDED", Const, 0, ""},
		{"SYS_ACCT", Const, 0, ""},
		{"SYS_ADD_KEY", Const, 0, ""},
		{"SYS_ADD_PROFIL", Const, 0, ""},
		{"SYS_ADJFREQ", Const, 1, ""},
		{"SYS_ADJTIME", Const, 0, ""},
		{"SYS_ADJTIMEX", Const, 0, ""},
		{"SYS_AFS_SYSCALL", Const, 0, ""},
		{"SYS_AIO_CANCEL", Const, 0, ""},
		{"SYS_AIO_ERROR", Const, 0, ""},
		{"SYS_AIO_FSYNC", Const, 0, ""},
		{"SYS_AIO_MLOCK", Const, 14, ""},
		{"SYS_AIO_READ", Const, 0, ""},
		{"SYS_AIO_RETURN", Const, 0, ""},
		{"SYS_AIO_SUSPEND", Const, 0, ""},
		{"SYS_AIO_SUSPEND_NOCANCEL", Const, 0, ""},
		{"SYS_AIO_WAITCOMPLETE", Const, 14, ""},
		{"SYS_AIO_WRITE", Const, 0, ""},
		{"SYS_ALARM", Const, 0, ""},
		{"SYS_ARCH_PRCTL", Const, 0, ""},
		{"SYS_ARM_FADVISE64_64", Const, 0, ""},
		{"SYS_ARM_SYNC_FILE_RANGE", Const, 0, ""},
		{"SYS_ATGETMSG", Const, 0, ""},
		{"SYS_ATPGETREQ", Const, 0, ""},
		{"SYS_ATPGETRSP", Const, 0, ""},
		{"SYS_ATPSNDREQ", Const, 0, ""},
		{"SYS_ATPSNDRSP", Const, 0, ""},
		{"SYS_ATPUTMSG", Const, 0, ""},
		{"SYS_ATSOCKET", Const, 0, ""},
		{"SYS_AUDIT", Const, 0, ""},
		{"SYS_AUDITCTL", Const, 0, ""},
		{"SYS_AUDITON", Const, 0, ""},
		{"SYS_AUDIT_SESSION_JOIN", Const, 0, ""},
		{"SYS_AUDIT_SESSION_PORT", Const, 0, ""},
		{"SYS_AUDIT_SESSION_SELF", Const, 0, ""},
		{"SYS_BDFLUSH", Const, 0, ""},
		{"SYS_BIND", Const, 0, ""},
		{"SYS_BINDAT", Const, 3, ""},
		{"SYS_BREAK", Const, 0, ""},
		{"SYS_BRK", Const, 0, ""},
		{"SYS_BSDTHREAD_CREATE", Const, 0, ""},
		{"SYS_BSDTHREAD_REGISTER", Const, 0, ""},
		{"SYS_BSDTHREAD_TERMINATE", Const, 0, ""},
		{"SYS_CAPGET", Const, 0, ""},
		{"SYS_CAPSET", Const, 0, ""},
		{"SYS_CAP_ENTER", Const, 0, ""},
		{"SYS_CAP_FCNTLS_GET", Const, 1, ""},
		{"SYS_CAP_FCNTLS_LIMIT", Const, 1, ""},
		{"SYS_CAP_GETMODE", Const, 0, ""},
		{"SYS_CAP_GETRIGHTS", Const, 0, ""},
		{"SYS_CAP_IOCTLS_GET", Const, 1, ""},
		{"SYS_CAP_IOCTLS_LIMIT", Const, 1, ""},
		{"SYS_CAP_NEW", Const, 0, ""},
		{"SYS_CAP_RIGHTS_GET", Const, 1, ""},
		{"SYS_CAP_RIGHTS_LIMIT", Const, 1, ""},
		{"SYS_CHDIR", Const, 0, ""},
		{"SYS_CHFLAGS", Const, 0, ""},
		{"SYS_CHFLAGSAT", Const, 3, ""},
		{"SYS_CHMOD", Const, 0, ""},
		{"SYS_CHMOD_EXTENDED", Const, 0, ""},
		{"SYS_CHOWN", Const, 0, ""},
		{"SYS_CHOWN32", Const, 0, ""},
		{"SYS_CHROOT", Const, 0, ""},
		{"SYS_CHUD", Const, 0, ""},
		{"SYS_CLOCK_ADJTIME", Const, 0, ""},
		{"SYS_CLOCK_GETCPUCLOCKID2", Const, 1, ""},
		{"SYS_CLOCK_GETRES", Const, 0, ""},
		{"SYS_CLOCK_GETTIME", Const, 0, ""},
		{"SYS_CLOCK_NANOSLEEP", Const, 0, ""},
		{"SYS_CLOCK_SETTIME", Const, 0, ""},
		{"SYS_CLONE", Const, 0, ""},
		{"SYS_CLOSE", Const, 0, ""},
		{"SYS_CLOSEFROM", Const, 0, ""},
		{"SYS_CLOSE_NOCANCEL", Const, 0, ""},
		{"SYS_CONNECT", Const, 0, ""},
		{"SYS_CONNECTAT", Const, 3, ""},
		{"SYS_CONNECT_NOCANCEL", Const, 0, ""},
		{"SYS_COPYFILE", Const, 0, ""},
		{"SYS_CPUSET", Const, 0, ""},
		{"SYS_CPUSET_GETAFFINITY", Const, 0, ""},
		{"SYS_CPUSET_GETID", Const, 0, ""},
		{"SYS_CPUSET_SETAFFINITY", Const, 0, ""},
		{"SYS_CPUSET_SETID", Const, 0, ""},
		{"SYS_CREAT", Const, 0, ""},
		{"SYS_CREATE_MODULE", Const, 0, ""},
		{"SYS_CSOPS", Const, 0, ""},
		{"SYS_CSOPS_AUDITTOKEN", Const, 16, ""},
		{"SYS_DELETE", Const, 0, ""},
		{"SYS_DELETE_MODULE", Const, 0, ""},
		{"SYS_DUP", Const, 0, ""},
		{"SYS_DUP2", Const, 0, ""},
		{"SYS_DUP3", Const, 0, ""},
		{"SYS_EACCESS", Const, 0, ""},
		{"SYS_EPOLL_CREATE", Const, 0, ""},
		{"SYS_EPOLL_CREATE1", Const, 0, ""},
		{"SYS_EPOLL_CTL", Const, 0, ""},
		{"SYS_EPOLL_CTL_OLD", Const, 0, ""},
		{"SYS_EPOLL_PWAIT", Const, 0, ""},
		{"SYS_EPOLL_WAIT", Const, 0, ""},
		{"SYS_EPOLL_WAIT_OLD", Const, 0, ""},
		{"SYS_EVENTFD", Const, 0, ""},
		{"SYS_EVENTFD2", Const, 0, ""},
		{"SYS_EXCHANGEDATA", Const, 0, ""},
		{"SYS_EXECVE", Const, 0, ""},
		{"SYS_EXIT", Const, 0, ""},
		{"SYS_EXIT_GROUP", Const, 0, ""},
		{"SYS_EXTATTRCTL", Const, 0, ""},
		{"SYS_EXTATTR_DELETE_FD", Const, 0, ""},
		{"SYS_EXTATTR_DELETE_FILE", Const, 0, ""},
		{"SYS_EXTATTR_DELETE_LINK", Const, 0, ""},
		{"SYS_EXTATTR_GET_FD", Const, 0, ""},
		{"SYS_EXTATTR_GET_FILE", Const, 0, ""},
		{"SYS_EXTATTR_GET_LINK", Const, 0, ""},
		{"SYS_EXTATTR_LIST_FD", Const, 0, ""},
		{"SYS_EXTATTR_LIST_FILE", Const, 0, ""},
		{"SYS_EXTATTR_LIST_LINK", Const, 0, ""},
		{"SYS_EXTATTR_SET_FD", Const, 0, ""},
		{"SYS_EXTATTR_SET_FILE", Const, 0, ""},
		{"SYS_EXTATTR_SET_LINK", Const, 0, ""},
		{"SYS_FACCESSAT", Const, 0, ""},
		{"SYS_FADVISE64", Const, 0, ""},
		{"SYS_FADVISE64_64", Const, 0, ""},
		{"SYS_FALLOCATE", Const, 0, ""},
		{"SYS_FANOTIFY_INIT", Const, 0, ""},
		{"SYS_FANOTIFY_MARK", Const, 0, ""},
		{"SYS_FCHDIR", Const, 0, ""},
		{"SYS_FCHFLAGS", Const, 0, ""},
		{"SYS_FCHMOD", Const, 0, ""},
		{"SYS_FCHMODAT", Const, 0, ""},
		{"SYS_FCHMOD_EXTENDED", Const, 0, ""},
		{"SYS_FCHOWN", Const, 0, ""},
		{"SYS_FCHOWN32", Const, 0, ""},
		{"SYS_FCHOWNAT", Const, 0, ""},
		{"SYS_FCHROOT", Const, 1, ""},
		{"SYS_FCNTL", Const, 0, ""},
		{"SYS_FCNTL64", Const, 0, ""},
		{"SYS_FCNTL_NOCANCEL", Const, 0, ""},
		{"SYS_FDATASYNC", Const, 0, ""},
		{"SYS_FEXECVE", Const, 0, ""},
		{"SYS_FFCLOCK_GETCOUNTER", Const, 0, ""},
		{"SYS_FFCLOCK_GETESTIMATE", Const, 0, ""},
		{"SYS_FFCLOCK_SETESTIMATE", Const, 0, ""},
		{"SYS_FFSCTL", Const, 0, ""},
		{"SYS_FGETATTRLIST", Const, 0, ""},
		{"SYS_FGETXATTR", Const, 0, ""},
		{"SYS_FHOPEN", Const, 0, ""},
		{"SYS_FHSTAT", Const, 0, ""},
		{"SYS_FHSTATFS", Const, 0, ""},
		{"SYS_FILEPORT_MAKEFD", Const, 0, ""},
		{"SYS_FILEPORT_MAKEPORT", Const, 0, ""},
		{"SYS_FKTRACE", Const, 1, ""},
		{"SYS_FLISTXATTR", Const, 0, ""},
		{"SYS_FLOCK", Const, 0, ""},
		{"SYS_FORK", Const, 0, ""},
		{"SYS_FPATHCONF", Const, 0, ""},
		{"SYS_FREEBSD6_FTRUNCATE", Const, 0, ""},
		{"SYS_FREEBSD6_LSEEK", Const, 0, ""},
		{"SYS_FREEBSD6_MMAP", Const, 0, ""},
		{"SYS_FREEBSD6_PREAD", Const, 0, ""},
		{"SYS_FREEBSD6_PWRITE", Const, 0, ""},
		{"SYS_FREEBSD6_TRUNCATE", Const, 0, ""},
		{"SYS_FREMOVEXATTR", Const, 0, ""},
		{"SYS_FSCTL", Const, 0, ""},
		{"SYS_FSETATTRLIST", Const, 0, ""},
		{"SYS_FSETXATTR", Const, 0, ""},
		{"SYS_FSGETPATH", Const, 0, ""},
		{"SYS_FSTAT", Const, 0, ""},
		{"SYS_FSTAT64", Const, 0, ""},
		{"SYS_FSTAT64_EXTENDED", Const, 0, ""},
		{"SYS_FSTATAT", Const, 0, ""},
		{"SYS_FSTATAT64", Const, 0, ""},
		{"SYS_FSTATFS", Const, 0, ""},
		{"SYS_FSTATFS64", Const, 0, ""},
		{"SYS_FSTATV", Const, 0, ""},
		{"SYS_FSTATVFS1", Const, 1, ""},
		{"SYS_FSTAT_EXTENDED", Const, 0, ""},
		{"SYS_FSYNC", Const, 0, ""},
		{"SYS_FSYNC_NOCANCEL", Const, 0, ""},
		{"SYS_FSYNC_RANGE", Const, 1, ""},
		{"SYS_FTIME", Const, 0, ""},
		{"SYS_FTRUNCATE", Const, 0, ""},
		{"SYS_FTRUNCATE64", Const, 0, ""},
		{"SYS_FUTEX", Const, 0, ""},
		{"SYS_FUTIMENS", Const, 1, ""},
		{"SYS_FUTIMES", Const, 0, ""},
		{"SYS_FUTIMESAT", Const, 0, ""},
		{"SYS_GETATTRLIST", Const, 0, ""},
		{"SYS_GETAUDIT", Const, 0, ""},
		{"SYS_GETAUDIT_ADDR", Const, 0, ""},
		{"SYS_GETAUID", Const, 0, ""},
		{"SYS_GETCONTEXT", Const, 0, ""},
		{"SYS_GETCPU", Const, 0, ""},
		{"SYS_GETCWD", Const, 0, ""},
		{"SYS_GETDENTS", Const, 0, ""},
		{"SYS_GETDENTS64", Const, 0, ""},
		{"SYS_GETDIRENTRIES", Const, 0, ""},
		{"SYS_GETDIRENTRIES64", Const, 0, ""},
		{"SYS_GETDIRENTRIESATTR", Const, 0, ""},
		{"SYS_GETDTABLECOUNT", Const, 1, ""},
		{"SYS_GETDTABLESIZE", Const, 0, ""},
		{"SYS_GETEGID", Const, 0, ""},
		{"SYS_GETEGID32", Const, 0, ""},
		{"SYS_GETEUID", Const, 0, ""},
		{"SYS_GETEUID32", Const, 0, ""},
		{"SYS_GETFH", Const, 0, ""},
		{"SYS_GETFSSTAT", Const, 0, ""},
		{"SYS_GETFSSTAT64", Const, 0, ""},
		{"SYS_GETGID", Const, 0, ""},
		{"SYS_GETGID32", Const, 0, ""},
		{"SYS_GETGROUPS", Const, 0, ""},
		{"SYS_GETGROUPS32", Const, 0, ""},
		{"SYS_GETHOSTUUID", Const, 0, ""},
		{"SYS_GETITIMER", Const, 0, ""},
		{"SYS_GETLCID", Const, 0, ""},
		{"SYS_GETLOGIN", Const, 0, ""},
		{"SYS_GETLOGINCLASS", Const, 0, ""},
		{"SYS_GETPEERNAME", Const, 0, ""},
		{"SYS_GETPGID", Const, 0, ""},
		{"SYS_GETPGRP", Const, 0, ""},
		{"SYS_GETPID", Const, 0, ""},
		{"SYS_GETPMSG", Const, 0, ""},
		{"SYS_GETPPID", Const, 0, ""},
		{"SYS_GETPRIORITY", Const, 0, ""},
		{"SYS_GETRESGID", Const, 0, ""},
		{"SYS_GETRESGID32", Const, 0, ""},
		{"SYS_GETRESUID", Const, 0, ""},
		{"SYS_GETRESUID32", Const, 0, ""},
		{"SYS_GETRLIMIT", Const, 0, ""},
		{"SYS_GETRTABLE", Const, 1, ""},
		{"SYS_GETRUSAGE", Const, 0, ""},
		{"SYS_GETSGROUPS", Const, 0, ""},
		{"SYS_GETSID", Const, 0, ""},
		{"SYS_GETSOCKNAME", Const, 0, ""},
		{"SYS_GETSOCKOPT", Const, 0, ""},
		{"SYS_GETTHRID", Const, 1, ""},
		{"SYS_GETTID", Const, 0, ""},
		{"SYS_GETTIMEOFDAY", Const, 0, ""},
		{"SYS_GETUID", Const, 0, ""},
		{"SYS_GETUID32", Const, 0, ""},
		{"SYS_GETVFSSTAT", Const, 1, ""},
		{"SYS_GETWGROUPS", Const, 0, ""},
		{"SYS_GETXATTR", Const, 0, ""},
		{"SYS_GET_KERNEL_SYMS", Const, 0, ""},
		{"SYS_GET_MEMPOLICY", Const, 0, ""},
		{"SYS_GET_ROBUST_LIST", Const, 0, ""},
		{"SYS_GET_THREAD_AREA", Const, 0, ""},
		{"SYS_GSSD_SYSCALL", Const, 14, ""},
		{"SYS_GTTY", Const, 0, ""},
		{"SYS_IDENTITYSVC", Const, 0, ""},
		{"SYS_IDLE", Const, 0, ""},
		{"SYS_INITGROUPS", Const, 0, ""},
		{"SYS_INIT_MODULE", Const, 0, ""},
		{"SYS_INOTIFY_ADD_WATCH", Const, 0, ""},
		{"SYS_INOTIFY_INIT", Const, 0, ""},
		{"SYS_INOTIFY_INIT1", Const, 0, ""},
		{"SYS_INOTIFY_RM_WATCH", Const, 0, ""},
		{"SYS_IOCTL", Const, 0, ""},
		{"SYS_IOPERM", Const, 0, ""},
		{"SYS_IOPL", Const, 0, ""},
		{"SYS_IOPOLICYSYS", Const, 0, ""},
		{"SYS_IOPRIO_GET", Const, 0, ""},
		{"SYS_IOPRIO_SET", Const, 0, ""},
		{"SYS_IO_CANCEL", Const, 0, ""},
		{"SYS_IO_DESTROY", Const, 0, ""},
		{"SYS_IO_GETEVENTS", Const, 0, ""},
		{"SYS_IO_SETUP", Const, 0, ""},
		{"SYS_IO_SUBMIT", Const, 0, ""},
		{"SYS_IPC", Const, 0, ""},
		{"SYS_ISSETUGID", Const, 0, ""},
		{"SYS_JAIL", Const, 0, ""},
		{"SYS_JAIL_ATTACH", Const, 0, ""},
		{"SYS_JAIL_GET", Const, 0, ""},
		{"SYS_JAIL_REMOVE", Const, 0, ""},
		{"SYS_JAIL_SET", Const, 0, ""},
		{"SYS_KAS_INFO", Const, 16, ""},
		{"SYS_KDEBUG_TRACE", Const, 0, ""},
		{"SYS_KENV", Const, 0, ""},
		{"SYS_KEVENT", Const, 0, ""},
		{"SYS_KEVENT64", Const, 0, ""},
		{"SYS_KEXEC_LOAD", Const, 0, ""},
		{"SYS_KEYCTL", Const, 0, ""},
		{"SYS_KILL", Const, 0, ""},
		{"SYS_KLDFIND", Const, 0, ""},
		{"SYS_KLDFIRSTMOD", Const, 0, ""},
		{"SYS_KLDLOAD", Const, 0, ""},
		{"SYS_KLDNEXT", Const, 0, ""},
		{"SYS_KLDSTAT", Const, 0, ""},
		{"SYS_KLDSYM", Const, 0, ""},
		{"SYS_KLDUNLOAD", Const, 0, ""},
		{"SYS_KLDUNLOADF", Const, 0, ""},
		{"SYS_KMQ_NOTIFY", Const, 14, ""},
		{"SYS_KMQ_OPEN", Const, 14, ""},
		{"SYS_KMQ_SETATTR", Const, 14, ""},
		{"SYS_KMQ_TIMEDRECEIVE", Const, 14, ""},
		{"SYS_KMQ_TIMEDSEND", Const, 14, ""},
		{"SYS_KMQ_UNLINK", Const, 14, ""},
		{"SYS_KQUEUE", Const, 0, ""},
		{"SYS_KQUEUE1", Const, 1, ""},
		{"SYS_KSEM_CLOSE", Const, 14, ""},
		{"SYS_KSEM_DESTROY", Const, 14, ""},
		{"SYS_KSEM_GETVALUE", Const, 14, ""},
		{"SYS_KSEM_INIT", Const, 14, ""},
		{"SYS_KSEM_OPEN", Const, 14, ""},
		{"SYS_KSEM_POST", Const, 14, ""},
		{"SYS_KSEM_TIMEDWAIT", Const, 14, ""},
		{"SYS_KSEM_TRYWAIT", Const, 14, ""},
		{"SYS_KSEM_UNLINK", Const, 14, ""},
		{"SYS_KSEM_WAIT", Const, 14, ""},
		{"SYS_KTIMER_CREATE", Const, 0, ""},
		{"SYS_KTIMER_DELETE", Const, 0, ""},
		{"SYS_KTIMER_GETOVERRUN", Const, 0, ""},
		{"SYS_KTIMER_GETTIME", Const, 0, ""},
		{"SYS_KTIMER_SETTIME", Const, 0, ""},
		{"SYS_KTRACE", Const, 0, ""},
		{"SYS_LCHFLAGS", Const, 0, ""},
		{"SYS_LCHMOD", Const, 0, ""},
		{"SYS_LCHOWN", Const, 0, ""},
		{"SYS_LCHOWN32", Const, 0, ""},
		{"SYS_LEDGER", Const, 16, ""},
		{"SYS_LGETFH", Const, 0, ""},
		{"SYS_LGETXATTR", Const, 0, ""},
		{"SYS_LINK", Const, 0, ""},
		{"SYS_LINKAT", Const, 0, ""},
		{"SYS_LIO_LISTIO", Const, 0, ""},
		{"SYS_LISTEN", Const, 0, ""},
		{"SYS_LISTXATTR", Const, 0, ""},
		{"SYS_LLISTXATTR", Const, 0, ""},
		{"SYS_LOCK", Const, 0, ""},
		{"SYS_LOOKUP_DCOOKIE", Const, 0, ""},
		{"SYS_LPATHCONF", Const, 0, ""},
		{"SYS_LREMOVEXATTR", Const, 0, ""},
		{"SYS_LSEEK", Const, 0, ""},
		{"SYS_LSETXATTR", Const, 0, ""},
		{"SYS_LSTAT", Const, 0, ""},
		{"SYS_LSTAT64", Const, 0, ""},
		{"SYS_LSTAT64_EXTENDED", Const, 0, ""},
		{"SYS_LSTATV", Const, 0, ""},
		{"SYS_LSTAT_EXTENDED", Const, 0, ""},
		{"SYS_LUTIMES", Const, 0, ""},
		{"SYS_MAC_SYSCALL", Const, 0, ""},
		{"SYS_MADVISE", Const, 0, ""},
		{"SYS_MADVISE1", Const, 0, ""},
		{"SYS_MAXSYSCALL", Const, 0, ""},
		{"SYS_MBIND", Const, 0, ""},
		{"SYS_MIGRATE_PAGES", Const, 0, ""},
		{"SYS_MINCORE", Const, 0, ""},
		{"SYS_MINHERIT", Const, 0, ""},
		{"SYS_MKCOMPLEX", Const, 0, ""},
		{"SYS_MKDIR", Const, 0, ""},
		{"SYS_MKDIRAT", Const, 0, ""},
		{"SYS_MKDIR_EXTENDED", Const, 0, ""},
		{"SYS_MKFIFO", Const, 0, ""},
		{"SYS_MKFIFOAT", Const, 0, ""},
		{"SYS_MKFIFO_EXTENDED", Const, 0, ""},
		{"SYS_MKNOD", Const, 0, ""},
		{"SYS_MKNODAT", Const, 0, ""},
		{"SYS_MLOCK", Const, 0, ""},
		{"SYS_MLOCKALL", Const, 0, ""},
		{"SYS_MMAP", Const, 0, ""},
		{"SYS_MMAP2", Const, 0, ""},
		{"SYS_MODCTL", Const, 1, ""},
		{"SYS_MODFIND", Const, 0, ""},
		{"SYS_MODFNEXT", Const, 0, ""},
		{"SYS_MODIFY_LDT", Const, 0, ""},
		{"SYS_MODNEXT", Const, 0, ""},
		{"SYS_MODSTAT", Const, 0, ""},
		{"SYS_MODWATCH", Const, 0, ""},
		{"SYS_MOUNT", Const, 0, ""},
		{"SYS_MOVE_PAGES", Const, 0, ""},
		{"SYS_MPROTECT", Const, 0, ""},
		{"SYS_MPX", Const, 0, ""},
		{"SYS_MQUERY", Const, 1, ""},
		{"SYS_MQ_GETSETATTR", Const, 0, ""},
		{"SYS_MQ_NOTIFY", Const, 0, ""},
		{"SYS_MQ_OPEN", Const, 0, ""},
		{"SYS_MQ_TIMEDRECEIVE", Const, 0, ""},
		{"SYS_MQ_TIMEDSEND", Const, 0, ""},
		{"SYS_MQ_UNLINK", Const, 0, ""},
		{"SYS_MREMAP", Const, 0, ""},
		{"SYS_MSGCTL", Const, 0, ""},
		{"SYS_MSGGET", Const, 0, ""},
		{"SYS_MSGRCV", Const, 0, ""},
		{"SYS_MSGRCV_NOCANCEL", Const, 0, ""},
		{"SYS_MSGSND", Const, 0, ""},
		{"SYS_MSGSND_NOCANCEL", Const, 0, ""},
		{"SYS_MSGSYS", Const, 0, ""},
		{"SYS_MSYNC", Const, 0, ""},
		{"SYS_MSYNC_NOCANCEL", Const, 0, ""},
		{"SYS_MUNLOCK", Const, 0, ""},
		{"SYS_MUNLOCKALL", Const, 0, ""},
		{"SYS_MUNMAP", Const, 0, ""},
		{"SYS_NAME_TO_HANDLE_AT", Const, 0, ""},
		{"SYS_NANOSLEEP", Const, 0, ""},
		{"SYS_NEWFSTATAT", Const, 0, ""},
		{"SYS_NFSCLNT", Const, 0, ""},
		{"SYS_NFSSERVCTL", Const, 0, ""},
		{"SYS_NFSSVC", Const, 0, ""},
		{"SYS_NFSTAT", Const, 0, ""},
		{"SYS_NICE", Const, 0, ""},
		{"SYS_NLM_SYSCALL", Const, 14, ""},
		{"SYS_NLSTAT", Const, 0, ""},
		{"SYS_NMOUNT", Const, 0, ""},
		{"SYS_NSTAT", Const, 0, ""},
		{"SYS_NTP_ADJTIME", Const, 0, ""},
		{"SYS_NTP_GETTIME", Const, 0, ""},
		{"SYS_NUMA_GETAFFINITY", Const, 14, ""},
		{"SYS_NUMA_SETAFFINITY", Const, 14, ""},
		{"SYS_OABI_SYSCALL_BASE", Const, 0, ""},
		{"SYS_OBREAK", Const, 0, ""},
		{"SYS_OLDFSTAT", Const, 0, ""},
		{"SYS_OLDLSTAT", Const, 0, ""},
		{"SYS_OLDOLDUNAME", Const, 0, ""},
		{"SYS_OLDSTAT", Const, 0, ""},
		{"SYS_OLDUNAME", Const, 0, ""},
		{"SYS_OPEN", Const, 0, ""},
		{"SYS_OPENAT", Const, 0, ""},
		{"SYS_OPENBSD_POLL", Const, 0, ""},
		{"SYS_OPEN_BY_HANDLE_AT", Const, 0, ""},
		{"SYS_OPEN_DPROTECTED_NP", Const, 16, ""},
		{"SYS_OPEN_EXTENDED", Const, 0, ""},
		{"SYS_OPEN_NOCANCEL", Const, 0, ""},
		{"SYS_OVADVISE", Const, 0, ""},
		{"SYS_PACCEPT", Const, 1, ""},
		{"SYS_PATHCONF", Const, 0, ""},
		{"SYS_PAUSE", Const, 0, ""},
		{"SYS_PCICONFIG_IOBASE", Const, 0, ""},
		{"SYS_PCICONFIG_READ", Const, 0, ""},
		{"SYS_PCICONFIG_WRITE", Const, 0, ""},
		{"SYS_PDFORK", Const, 0, ""},
		{"SYS_PDGETPID", Const, 0, ""},
		{"SYS_PDKILL", Const, 0, ""},
		{"SYS_PERF_EVENT_OPEN", Const, 0, ""},
		{"SYS_PERSONALITY", Const, 0, ""},
		{"SYS_PID_HIBERNATE", Const, 0, ""},
		{"SYS_PID_RESUME", Const, 0, ""},
		{"SYS_PID_SHUTDOWN_SOCKETS", Const, 0, ""},
		{"SYS_PID_SUSPEND", Const, 0, ""},
		{"SYS_PIPE", Const, 0, ""},
		{"SYS_PIPE2", Const, 0, ""},
		{"SYS_PIVOT_ROOT", Const, 0, ""},
		{"SYS_PMC_CONTROL", Const, 1, ""},
		{"SYS_PMC_GET_INFO", Const, 1, ""},
		{"SYS_POLL", Const, 0, ""},
		{"SYS_POLLTS", Const, 1, ""},
		{"SYS_POLL_NOCANCEL", Const, 0, ""},
		{"SYS_POSIX_FADVISE", Const, 0, ""},
		{"SYS_POSIX_FALLOCATE", Const, 0, ""},
		{"SYS_POSIX_OPENPT", Const, 0, ""},
		{"SYS_POSIX_SPAWN", Const, 0, ""},
		{"SYS_PPOLL", Const, 0, ""},
		{"SYS_PRCTL", Const, 0, ""},
		{"SYS_PREAD", Const, 0, ""},
		{"SYS_PREAD64", Const, 0, ""},
		{"SYS_PREADV", Const, 0, ""},
		{"SYS_PREAD_NOCANCEL", Const, 0, ""},
		{"SYS_PRLIMIT64", Const, 0, ""},
		{"SYS_PROCCTL", Const, 3, ""},
		{"SYS_PROCESS_POLICY", Const, 0, ""},
		{"SYS_PROCESS_VM_READV", Const, 0, ""},
		{"SYS_PROCESS_VM_WRITEV", Const, 0, ""},
		{"SYS_PROC_INFO", Const, 0, ""},
		{"SYS_PROF", Const, 0, ""},
		{"SYS_PROFIL", Const, 0, ""},
		{"SYS_PSELECT", Const, 0, ""},
		{"SYS_PSELECT6", Const, 0, ""},
		{"SYS_PSET_ASSIGN", Const, 1, ""},
		{"SYS_PSET_CREATE", Const, 1, ""},
		{"SYS_PSET_DESTROY", Const, 1, ""},
		{"SYS_PSYNCH_CVBROAD", Const, 0, ""},
		{"SYS_PSYNCH_CVCLRPREPOST", Const, 0, ""},
		{"SYS_PSYNCH_CVSIGNAL", Const, 0, ""},
		{"SYS_PSYNCH_CVWAIT", Const, 0, ""},
		{"SYS_PSYNCH_MUTEXDROP", Const, 0, ""},
		{"SYS_PSYNCH_MUTEXWAIT", Const, 0, ""},
		{"SYS_PSYNCH_RW_DOWNGRADE", Const, 0, ""},
		{"SYS_PSYNCH_RW_LONGRDLOCK", Const, 0, ""},
		{"SYS_PSYNCH_RW_RDLOCK", Const, 0, ""},
		{"SYS_PSYNCH_RW_UNLOCK", Const, 0, ""},
		{"SYS_PSYNCH_RW_UNLOCK2", Const, 0, ""},
		{"SYS_PSYNCH_RW_UPGRADE", Const, 0, ""},
		{"SYS_PSYNCH_RW_WRLOCK", Const, 0, ""},
		{"SYS_PSYNCH_RW_YIELDWRLOCK", Const, 0, ""},
		{"SYS_PTRACE", Const, 0, ""},
		{"SYS_PUTPMSG", Const, 0, ""},
		{"SYS_PWRITE", Const, 0, ""},
		{"SYS_PWRITE64", Const, 0, ""},
		{"SYS_PWRITEV", Const, 0, ""},
		{"SYS_PWRITE_NOCANCEL", Const, 0, ""},
		{"SYS_QUERY_MODULE", Const, 0, ""},
		{"SYS_QUOTACTL", Const, 0, ""},
		{"SYS_RASCTL", Const, 1, ""},
		{"SYS_RCTL_ADD_RULE", Const, 0, ""},
		{"SYS_RCTL_GET_LIMITS", Const, 0, ""},
		{"SYS_RCTL_GET_RACCT", Const, 0, ""},
		{"SYS_RCTL_GET_RULES", Const, 0, ""},
		{"SYS_RCTL_REMOVE_RULE", Const, 0, ""},
		{"SYS_READ", Const, 0, ""},
		{"SYS_READAHEAD", Const, 0, ""},
		{"SYS_READDIR", Const, 0, ""},
		{"SYS_READLINK", Const, 0, ""},
		{"SYS_READLINKAT", Const, 0, ""},
		{"SYS_READV", Const, 0, ""},
		{"SYS_READV_NOCANCEL", Const, 0, ""},
		{"SYS_READ_NOCANCEL", Const, 0, ""},
		{"SYS_REBOOT", Const, 0, ""},
		{"SYS_RECV", Const, 0, ""},
		{"SYS_RECVFROM", Const, 0, ""},
		{"SYS_RECVFROM_NOCANCEL", Const, 0, ""},
		{"SYS_RECVMMSG", Const, 0, ""},
		{"SYS_RECVMSG", Const, 0, ""},
		{"SYS_RECVMSG_NOCANCEL", Const, 0, ""},
		{"SYS_REMAP_FILE_PAGES", Const, 0, ""},
		{"SYS_REMOVEXATTR", Const, 0, ""},
		{"SYS_RENAME", Const, 0, ""},
		{"SYS_RENAMEAT", Const, 0, ""},
		{"SYS_REQUEST_KEY", Const, 0, ""},
		{"SYS_RESTART_SYSCALL", Const, 0, ""},
		{"SYS_REVOKE", Const, 0, ""},
		{"SYS_RFORK", Const, 0, ""},
		{"SYS_RMDIR", Const, 0, ""},
		{"SYS_RTPRIO", Const, 0, ""},
		{"SYS_RTPRIO_THREAD", Const, 0, ""},
		{"SYS_RT_SIGACTION", Const, 0, ""},
		{"SYS_RT_SIGPENDING", Const, 0, ""},
		{"SYS_RT_SIGPROCMASK", Const, 0, ""},
		{"SYS_RT_SIGQUEUEINFO", Const, 0, ""},
		{"SYS_RT_SIGRETURN", Const, 0, ""},
		{"SYS_RT_SIGSUSPEND", Const, 0, ""},
		{"SYS_RT_SIGTIMEDWAIT", Const, 0, ""},
		{"SYS_RT_TGSIGQUEUEINFO", Const, 0, ""},
		{"SYS_SBRK", Const, 0, ""},
		{"SYS_SCHED_GETAFFINITY", Const, 0, ""},
		{"SYS_SCHED_GETPARAM", Const, 0, ""},
		{"SYS_SCHED_GETSCHEDULER", Const, 0, ""},
		{"SYS_SCHED_GET_PRIORITY_MAX", Const, 0, ""},
		{"SYS_SCHED_GET_PRIORITY_MIN", Const, 0, ""},
		{"SYS_SCHED_RR_GET_INTERVAL", Const, 0, ""},
		{"SYS_SCHED_SETAFFINITY", Const, 0, ""},
		{"SYS_SCHED_SETPARAM", Const, 0, ""},
		{"SYS_SCHED_SETSCHEDULER", Const, 0, ""},
		{"SYS_SCHED_YIELD", Const, 0, ""},
		{"SYS_SCTP_GENERIC_RECVMSG", Const, 0, ""},
		{"SYS_SCTP_GENERIC_SENDMSG", Const, 0, ""},
		{"SYS_SCTP_GENERIC_SENDMSG_IOV", Const, 0, ""},
		{"SYS_SCTP_PEELOFF", Const, 0, ""},
		{"SYS_SEARCHFS", Const, 0, ""},
		{"SYS_SECURITY", Const, 0, ""},
		{"SYS_SELECT", Const, 0, ""},
		{"SYS_SELECT_NOCANCEL", Const, 0, ""},
		{"SYS_SEMCONFIG", Const, 1, ""},
		{"SYS_SEMCTL", Const, 0, ""},
		{"SYS_SEMGET", Const, 0, ""},
		{"SYS_SEMOP", Const, 0, ""},
		{"SYS_SEMSYS", Const, 0, ""},
		{"SYS_SEMTIMEDOP", Const, 0, ""},
		{"SYS_SEM_CLOSE", Const, 0, ""},
		{"SYS_SEM_DESTROY", Const, 0, ""},
		{"SYS_SEM_GETVALUE", Const, 0, ""},
		{"SYS_SEM_INIT", Const, 0, ""},
		{"SYS_SEM_OPEN", Const, 0, ""},
		{"SYS_SEM_POST", Const, 0, ""},
		{"SYS_SEM_TRYWAIT", Const, 0, ""},
		{"SYS_SEM_UNLINK", Const, 0, ""},
		{"SYS_SEM_WAIT", Const, 0, ""},
		{"SYS_SEM_WAIT_NOCANCEL", Const, 0, ""},
		{"SYS_SEND", Const, 0, ""},
		{"SYS_SENDFILE", Const, 0, ""},
		{"SYS_SENDFILE64", Const, 0, ""},
		{"SYS_SENDMMSG", Const, 0, ""},
		{"SYS_SENDMSG", Const, 0, ""},
		{"SYS_SENDMSG_NOCANCEL", Const, 0, ""},
		{"SYS_SENDTO", Const, 0, ""},
		{"SYS_SENDTO_NOCANCEL", Const, 0, ""},
		{"SYS_SETATTRLIST", Const, 0, ""},
		{"SYS_SETAUDIT", Const, 0, ""},
		{"SYS_SETAUDIT_ADDR", Const, 0, ""},
		{"SYS_SETAUID", Const, 0, ""},
		{"SYS_SETCONTEXT", Const, 0, ""},
		{"SYS_SETDOMAINNAME", Const, 0, ""},
		{"SYS_SETEGID", Const, 0, ""},
		{"SYS_SETEUID", Const, 0, ""},
		{"SYS_SETFIB", Const, 0, ""},
		{"SYS_SETFSGID", Const, 0, ""},
		{"SYS_SETFSGID32", Const, 0, ""},
		{"SYS_SETFSUID", Const, 0, ""},
		{"SYS_SETFSUID32", Const, 0, ""},
		{"SYS_SETGID", Const, 0, ""},
		{"SYS_SETGID32", Const, 0, ""},
		{"SYS_SETGROUPS", Const, 0, ""},
		{"SYS_SETGROUPS32", Const, 0, ""},
		{"SYS_SETHOSTNAME", Const, 0, ""},
		{"SYS_SETITIMER", Const, 0, ""},
		{"SYS_SETLCID", Const, 0, ""},
		{"SYS_SETLOGIN", Const, 0, ""},
		{"SYS_SETLOGINCLASS", Const, 0, ""},
		{"SYS_SETNS", Const, 0, ""},
		{"SYS_SETPGID", Const, 0, ""},
		{"SYS_SETPRIORITY", Const, 0, ""},
		{"SYS_SETPRIVEXEC", Const, 0, ""},
		{"SYS_SETREGID", Const, 0, ""},
		{"SYS_SETREGID32", Const, 0, ""},
		{"SYS_SETRESGID", Const, 0, ""},
		{"SYS_SETRESGID32", Const, 0, ""},
		{"SYS_SETRESUID", Const, 0, ""},
		{"SYS_SETRESUID32", Const, 0, ""},
		{"SYS_SETREUID", Const, 0, ""},
		{"SYS_SETREUID32", Const, 0, ""},
		{"SYS_SETRLIMIT", Const, 0, ""},
		{"SYS_SETRTABLE", Const, 1, ""},
		{"SYS_SETSGROUPS", Const, 0, ""},
		{"SYS_SETSID", Const, 0, ""},
		{"SYS_SETSOCKOPT", Const, 0, ""},
		{"SYS_SETTID", Const, 0, ""},
		{"SYS_SETTID_WITH_PID", Const, 0, ""},
		{"SYS_SETTIMEOFDAY", Const, 0, ""},
		{"SYS_SETUID", Const, 0, ""},
		{"SYS_SETUID32", Const, 0, ""},
		{"SYS_SETWGROUPS", Const, 0, ""},
		{"SYS_SETXATTR", Const, 0, ""},
		{"SYS_SET_MEMPOLICY", Const, 0, ""},
		{"SYS_SET_ROBUST_LIST", Const, 0, ""},
		{"SYS_SET_THREAD_AREA", Const, 0, ""},
		{"SYS_SET_TID_ADDRESS", Const, 0, ""},
		{"SYS_SGETMASK", Const, 0, ""},
		{"SYS_SHARED_REGION_CHECK_NP", Const, 0, ""},
		{"SYS_SHARED_REGION_MAP_AND_SLIDE_NP", Const, 0, ""},
		{"SYS_SHMAT", Const, 0, ""},
		{"SYS_SHMCTL", Const, 0, ""},
		{"SYS_SHMDT", Const, 0, ""},
		{"SYS_SHMGET", Const, 0, ""},
		{"SYS_SHMSYS", Const, 0, ""},
		{"SYS_SHM_OPEN", Const, 0, ""},
		{"SYS_SHM_UNLINK", Const, 0, ""},
		{"SYS_SHUTDOWN", Const, 0, ""},
		{"SYS_SIGACTION", Const, 0, ""},
		{"SYS_SIGALTSTACK", Const, 0, ""},
		{"SYS_SIGNAL", Const, 0, ""},
		{"SYS_SIGNALFD", Const, 0, ""},
		{"SYS_SIGNALFD4", Const, 0, ""},
		{"SYS_SIGPENDING", Const, 0, ""},
		{"SYS_SIGPROCMASK", Const, 0, ""},
		{"SYS_SIGQUEUE", Const, 0, ""},
		{"SYS_SIGQUEUEINFO", Const, 1, ""},
		{"SYS_SIGRETURN", Const, 0, ""},
		{"SYS_SIGSUSPEND", Const, 0, ""},
		{"SYS_SIGSUSPEND_NOCANCEL", Const, 0, ""},
		{"SYS_SIGTIMEDWAIT", Const, 0, ""},
		{"SYS_SIGWAIT", Const, 0, ""},
		{"SYS_SIGWAITINFO", Const, 0, ""},
		{"SYS_SOCKET", Const, 0, ""},
		{"SYS_SOCKETCALL", Const, 0, ""},
		{"SYS_SOCKETPAIR", Const, 0, ""},
		{"SYS_SPLICE", Const, 0, ""},
		{"SYS_SSETMASK", Const, 0, ""},
		{"SYS_SSTK", Const, 0, ""},
		{"SYS_STACK_SNAPSHOT", Const, 0, ""},
		{"SYS_STAT", Const, 0, ""},
		{"SYS_STAT64", Const, 0, ""},
		{"SYS_STAT64_EXTENDED", Const, 0, ""},
		{"SYS_STATFS", Const, 0, ""},
		{"SYS_STATFS64", Const, 0, ""},
		{"SYS_STATV", Const, 0, ""},
		{"SYS_STATVFS1", Const, 1, ""},
		{"SYS_STAT_EXTENDED", Const, 0, ""},
		{"SYS_STIME", Const, 0, ""},
		{"SYS_STTY", Const, 0, ""},
		{"SYS_SWAPCONTEXT", Const, 0, ""},
		{"SYS_SWAPCTL", Const, 1, ""},
		{"SYS_SWAPOFF", Const, 0, ""},
		{"SYS_SWAPON", Const, 0, ""},
		{"SYS_SYMLINK", Const, 0, ""},
		{"SYS_SYMLINKAT", Const, 0, ""},
		{"SYS_SYNC", Const, 0, ""},
		{"SYS_SYNCFS", Const, 0, ""},
		{"SYS_SYNC_FILE_RANGE", Const, 0, ""},
		{"SYS_SYSARCH", Const, 0, ""},
		{"SYS_SYSCALL", Const, 0, ""},
		{"SYS_SYSCALL_BASE", Const, 0, ""},
		{"SYS_SYSFS", Const, 0, ""},
		{"SYS_SYSINFO", Const, 0, ""},
		{"SYS_SYSLOG", Const, 0, ""},
		{"SYS_TEE", Const, 0, ""},
		{"SYS_TGKILL", Const, 0, ""},
		{"SYS_THREAD_SELFID", Const, 0, ""},
		{"SYS_THR_CREATE", Const, 0, ""},
		{"SYS_THR_EXIT", Const, 0, ""},
		{"SYS_THR_KILL", Const, 0, ""},
		{"SYS_THR_KILL2", Const, 0, ""},
		{"SYS_THR_NEW", Const, 0, ""},
		{"SYS_THR_SELF", Const, 0, ""},
		{"SYS_THR_SET_NAME", Const, 0, ""},
		{"SYS_THR_SUSPEND", Const, 0, ""},
		{"SYS_THR_WAKE", Const, 0, ""},
		{"SYS_TIME", Const, 0, ""},
		{"SYS_TIMERFD_CREATE", Const, 0, ""},
		{"SYS_TIMERFD_GETTIME", Const, 0, ""},
		{"SYS_TIMERFD_SETTIME", Const, 0, ""},
		{"SYS_TIMER_CREATE", Const, 0, ""},
		{"SYS_TIMER_DELETE", Const, 0, ""},
		{"SYS_TIMER_GETOVERRUN", Const, 0, ""},
		{"SYS_TIMER_GETTIME", Const, 0, ""},
		{"SYS_TIMER_SETTIME", Const, 0, ""},
		{"SYS_TIMES", Const, 0, ""},
		{"SYS_TKILL", Const, 0, ""},
		{"SYS_TRUNCATE", Const, 0, ""},
		{"SYS_TRUNCATE64", Const, 0, ""},
		{"SYS_TUXCALL", Const, 0, ""},
		{"SYS_UGETRLIMIT", Const, 0, ""},
		{"SYS_ULIMIT", Const, 0, ""},
		{"SYS_UMASK", Const, 0, ""},
		{"SYS_UMASK_EXTENDED", Const, 0, ""},
		{"SYS_UMOUNT", Const, 0, ""},
		{"SYS_UMOUNT2", Const, 0, ""},
		{"SYS_UNAME", Const, 0, ""},
		{"SYS_UNDELETE", Const, 0, ""},
		{"SYS_UNLINK", Const, 0, ""},
		{"SYS_UNLINKAT", Const, 0, ""},
		{"SYS_UNMOUNT", Const, 0, ""},
		{"SYS_UNSHARE", Const, 0, ""},
		{"SYS_USELIB", Const, 0, ""},
		{"SYS_USTAT", Const, 0, ""},
		{"SYS_UTIME", Const, 0, ""},
		{"SYS_UTIMENSAT", Const, 0, ""},
		{"SYS_UTIMES", Const, 0, ""},
		{"SYS_UTRACE", Const, 0, ""},
		{"SYS_UUIDGEN", Const, 0, ""},
		{"SYS_VADVISE", Const, 1, ""},
		{"SYS_VFORK", Const, 0, ""},
		{"SYS_VHANGUP", Const, 0, ""},
		{"SYS_VM86", Const, 0, ""},
		{"SYS_VM86OLD", Const, 0, ""},
		{"SYS_VMSPLICE", Const, 0, ""},
		{"SYS_VM_PRESSURE_MONITOR", Const, 0, ""},
		{"SYS_VSERVER", Const, 0, ""},
		{"SYS_WAIT4", Const, 0, ""},
		{"SYS_WAIT4_NOCANCEL", Const, 0, ""},
		{"SYS_WAIT6", Const, 1, ""},
		{"SYS_WAITEVENT", Const, 0, ""},
		{"SYS_WAITID", Const, 0, ""},
		{"SYS_WAITID_NOCANCEL", Const, 0, ""},
		{"SYS_WAITPID", Const, 0, ""},
		{"SYS_WATCHEVENT", Const, 0, ""},
		{"SYS_WORKQ_KERNRETURN", Const, 0, ""},
		{"SYS_WORKQ_OPEN", Const, 0, ""},
		{"SYS_WRITE", Const, 0, ""},
		{"SYS_WRITEV", Const, 0, ""},
		{"SYS_WRITEV_NOCANCEL", Const, 0, ""},
		{"SYS_WRITE_NOCANCEL", Const, 0, ""},
		{"SYS_YIELD", Const, 0, ""},
		{"SYS__LLSEEK", Const, 0, ""},
		{"SYS__LWP_CONTINUE", Const, 1, ""},
		{"SYS__LWP_CREATE", Const, 1, ""},
		{"SYS__LWP_CTL", Const, 1, ""},
		{"SYS__LWP_DETACH", Const, 1, ""},
		{"SYS__LWP_EXIT", Const, 1, ""},
		{"SYS__LWP_GETNAME", Const, 1, ""},
		{"SYS__LWP_GETPRIVATE", Const, 1, ""},
		{"SYS__LWP_KILL", Const, 1, ""},
		{"SYS__LWP_PARK", Const, 1, ""},
		{"SYS__LWP_SELF", Const, 1, ""},
		{"SYS__LWP_SETNAME", Const, 1, ""},
		{"SYS__LWP_SETPRIVATE", Const, 1, ""},
		{"SYS__LWP_SUSPEND", Const, 1, ""},
		{"SYS__LWP_UNPARK", Const, 1, ""},
		{"SYS__LWP_UNPARK_ALL", Const, 1, ""},
		{"SYS__LWP_WAIT", Const, 1, ""},
		{"SYS__LWP_WAKEUP", Const, 1, ""},
		{"SYS__NEWSELECT", Const, 0, ""},
		{"SYS__PSET_BIND", Const, 1, ""},
		{"SYS__SCHED_GETAFFINITY", Const, 1, ""},
		{"SYS__SCHED_GETPARAM", Const, 1, ""},
		{"SYS__SCHED_SETAFFINITY", Const, 1, ""},
		{"SYS__SCHED_SETPARAM", Const, 1, ""},
		{"SYS__SYSCTL", Const, 0, ""},
		{"SYS__UMTX_LOCK", Const, 0, ""},
		{"SYS__UMTX_OP", Const, 0, ""},
		{"SYS__UMTX_UNLOCK", Const, 0, ""},
		{"SYS___ACL_ACLCHECK_FD", Const, 0, ""},
		{"SYS___ACL_ACLCHECK_FILE", Const, 0, ""},
		{"SYS___ACL_ACLCHECK_LINK", Const, 0, ""},
		{"SYS___ACL_DELETE_FD", Const, 0, ""},
		{"SYS___ACL_DELETE_FILE", Const, 0, ""},
		{"SYS___ACL_DELETE_LINK", Const, 0, ""},
		{"SYS___ACL_GET_FD", Const, 0, ""},
		{"SYS___ACL_GET_FILE", Const, 0, ""},
		{"SYS___ACL_GET_LINK", Const, 0, ""},
		{"SYS___ACL_SET_FD", Const, 0, ""},
		{"SYS___ACL_SET_FILE", Const, 0, ""},
		{"SYS___ACL_SET_LINK", Const, 0, ""},
		{"SYS___CAP_RIGHTS_GET", Const, 14, ""},
		{"SYS___CLONE", Const, 1, ""},
		{"SYS___DISABLE_THREADSIGNAL", Const, 0, ""},
		{"SYS___GETCWD", Const, 0, ""},
		{"SYS___GETLOGIN", Const, 1, ""},
		{"SYS___GET_TCB", Const, 1, ""},
		{"SYS___MAC_EXECVE", Const, 0, ""},
		{"SYS___MAC_GETFSSTAT", Const, 0, ""},
		{"SYS___MAC_GET_FD", Const, 0, ""},
		{"SYS___MAC_GET_FILE", Const, 0, ""},
		{"SYS___MAC_GET_LCID", Const, 0, ""},
		{"SYS___MAC_GET_LCTX", Const, 0, ""},
		{"SYS___MAC_GET_LINK", Const, 0, ""},
		{"SYS___MAC_GET_MOUNT", Const, 0, ""},
		{"SYS___MAC_GET_PID", Const, 0, ""},
		{"SYS___MAC_GET_PROC", Const, 0, ""},
		{"SYS___MAC_MOUNT", Const, 0, ""},
		{"SYS___MAC_SET_FD", Const, 0, ""},
		{"SYS___MAC_SET_FILE", Const, 0, ""},
		{"SYS___MAC_SET_LCTX", Const, 0, ""},
		{"SYS___MAC_SET_LINK", Const, 0, ""},
		{"SYS___MAC_SET_PROC", Const, 0, ""},
		{"SYS___MAC_SYSCALL", Const, 0, ""},
		{"SYS___OLD_SEMWAIT_SIGNAL", Const, 0, ""},
		{"SYS___OLD_SEMWAIT_SIGNAL_NOCANCEL", Const, 0, ""},
		{"SYS___POSIX_CHOWN", Const, 1, ""},
		{"SYS___POSIX_FCHOWN", Const, 1, ""},
		{"SYS___POSIX_LCHOWN", Const, 1, ""},
		{"SYS___POSIX_RENAME", Const, 1, ""},
		{"SYS___PTHREAD_CANCELED", Const, 0, ""},
		{"SYS___PTHREAD_CHDIR", Const, 0, ""},
		{"SYS___PTHREAD_FCHDIR", Const, 0, ""},
		{"SYS___PTHREAD_KILL", Const, 0, ""},
		{"SYS___PTHREAD_MARKCANCEL", Const, 0, ""},
		{"SYS___PTHREAD_SIGMASK", Const, 0, ""},
		{"SYS___QUOTACTL", Const, 1, ""},
		{"SYS___SEMCTL", Const, 1, ""},
		{"SYS___SEMWAIT_SIGNAL", Const, 0, ""},
		{"SYS___SEMWAIT_SIGNAL_NOCANCEL", Const, 0, ""},
		{"SYS___SETLOGIN", Const, 1, ""},
		{"SYS___SETUGID", Const, 0, ""},
		{"SYS___SET_TCB", Const, 1, ""},
		{"SYS___SIGACTION_SIGTRAMP", Const, 1, ""},
		{"SYS___SIGTIMEDWAIT", Const, 1, ""},
		{"SYS___SIGWAIT", Const, 0, ""},
		{"SYS___SIGWAIT_NOCANCEL", Const, 0, ""},
		{"SYS___SYSCTL", Const, 0, ""},
		{"SYS___TFORK", Const, 1, ""},
		{"SYS___THREXIT", Const, 1, ""},
		{"SYS___THRSIGDIVERT", Const, 1, ""},
		{"SYS___THRSLEEP", Const, 1, ""},
		{"SYS___THRWAKEUP", Const, 1, ""},
		{"S_ARCH1", Const, 1, ""},
		{"S_ARCH2", Const, 1, ""},
		{"S_BLKSIZE", Const, 0, ""},
		{"S_IEXEC", Const, 0, ""},
		{"S_IFBLK", Const, 0, ""},
		{"S_IFCHR", Const, 0, ""},
		{"S_IFDIR", Const, 0, ""},
		{"S_IFIFO", Const, 0, ""},
		{"S_IFLNK", Const, 0, ""},
		{"S_IFMT", Const, 0, ""},
		{"S_IFREG", Const, 0, ""},
		{"S_IFSOCK", Const, 0, ""},
		{"S_IFWHT", Const, 0, ""},
		{"S_IREAD", Const, 0, ""},
		{"S_IRGRP", Const, 0, ""},
		{"S_IROTH", Const, 0, ""},
		{"S_IRUSR", Const, 0, ""},
		{"S_IRWXG", Const, 0, ""},
		{"S_IRWXO", Const, 0, ""},
		{"S_IRWXU", Const, 0, ""},
		{"S_ISGID", Const, 0, ""},
		{"S_ISTXT", Const, 0, ""},
		{"S_ISUID", Const, 0, ""},
		{"S_ISVTX", Const, 0, ""},
		{"S_IWGRP", Const, 0, ""},
		{"S_IWOTH", Const, 0, ""},
		{"S_IWRITE", Const, 0, ""},
		{"S_IWUSR", Const, 0, ""},
		{"S_IXGRP", Const, 0, ""},
		{"S_IXOTH", Const, 0, ""},
		{"S_IXUSR", Const, 0, ""},
		{"S_LOGIN_SET", Const, 1, ""},
		{"SecurityAttributes", Type, 0, ""},
		{"SecurityAttributes.InheritHandle", Field, 0, ""},
		{"SecurityAttributes.Length", Field, 0, ""},
		{"SecurityAttributes.SecurityDescriptor", Field, 0, ""},
		{"Seek", Func, 0, "func(fd int, offset int64, whence int) (off int64, err error)"},
		{"Select", Func, 0, "func(nfd int, r *FdSet, w *FdSet, e *FdSet, timeout *Timeval) (n int, err error)"},
		{"Sendfile", Func, 0, "func(outfd int, infd int, offset *int64, count int) (written int, err error)"},
		{"Sendmsg", Func, 0, "func(fd int, p []byte, oob []byte, to Sockaddr, flags int) (err error)"},
		{"SendmsgN", Func, 3, "func(fd int, p []byte, oob []byte, to Sockaddr, flags int) (n int, err error)"},
		{"Sendto", Func, 0, "func(fd int, p []byte, flags int, to Sockaddr) (err error)"},
		{"Servent", Type, 0, ""},
		{"Servent.Aliases", Field, 0, ""},
		{"Servent.Name", Field, 0, ""},
		{"Servent.Port", Field, 0, ""},
		{"Servent.Proto", Field, 0, ""},
		{"SetBpf", Func, 0, ""},
		{"SetBpfBuflen", Func, 0, ""},
		{"SetBpfDatalink", Func, 0, ""},
		{"SetBpfHeadercmpl", Func, 0, ""},
		{"SetBpfImmediate", Func, 0, ""},
		{"SetBpfInterface", Func, 0, ""},
		{"SetBpfPromisc", Func, 0, ""},
		{"SetBpfTimeout", Func, 0, ""},
		{"SetCurrentDirectory", Func, 0, ""},
		{"SetEndOfFile", Func, 0, ""},
		{"SetEnvironmentVariable", Func, 0, ""},
		{"SetFileAttributes", Func, 0, ""},
		{"SetFileCompletionNotificationModes", Func, 2, ""},
		{"SetFilePointer", Func, 0, ""},
		{"SetFileTime", Func, 0, ""},
		{"SetHandleInformation", Func, 0, ""},
		{"SetKevent", Func, 0, ""},
		{"SetLsfPromisc", Func, 0, "func(name string, m bool) error"},
		{"SetNonblock", Func, 0, "func(fd int, nonblocking bool) (err error)"},
		{"Setdomainname", Func, 0, "func(p []byte) (err error)"},
		{"Setegid", Func, 0, "func(egid int) (err error)"},
		{"Setenv", Func, 0, "func(key string, value string) error"},
		{"Seteuid", Func, 0, "func(euid int) (err error)"},
		{"Setfsgid", Func, 0, "func(gid int) (err error)"},
		{"Setfsuid", Func, 0, "func(uid int) (err error)"},
		{"Setgid", Func, 0, "func(gid int) (err error)"},
		{"Setgroups", Func, 0, "func(gids []int) (err error)"},
		{"Sethostname", Func, 0, "func(p []byte) (err error)"},
		{"Setlogin", Func, 0, ""},
		{"Setpgid", Func, 0, "func(pid int, pgid int) (err error)"},
		{"Setpriority", Func, 0, "func(which int, who int, prio int) (err error)"},
		{"Setprivexec", Func, 0, ""},
		{"Setregid", Func, 0, "func(rgid int, egid int) (err error)"},
		{"Setresgid", Func, 0, "func(rgid int, egid int, sgid int) (err error)"},
		{"Setresuid", Func, 0, "func(ruid int, euid int, suid int) (err error)"},
		{"Setreuid", Func, 0, "func(ruid int, euid int) (err error)"},
		{"Setrlimit", Func, 0, "func(resource int, rlim *Rlimit) error"},
		{"Setsid", Func, 0, "func() (pid int, err error)"},
		{"Setsockopt", Func, 0, ""},
		{"SetsockoptByte", Func, 0, "func(fd int, level int, opt int, value byte) (err error)"},
		{"SetsockoptICMPv6Filter", Func, 2, "func(fd int, level int, opt int, filter *ICMPv6Filter) error"},
		{"SetsockoptIPMreq", Func, 0, "func(fd int, level int, opt int, mreq *IPMreq) (err error)"},
		{"SetsockoptIPMreqn", Func, 0, "func(fd int, level int, opt int, mreq *IPMreqn) (err error)"},
		{"SetsockoptIPv6Mreq", Func, 0, "func(fd int, level int, opt int, mreq *IPv6Mreq) (err error)"},
		{"SetsockoptInet4Addr", Func, 0, "func(fd int, level int, opt int, value [4]byte) (err error)"},
		{"SetsockoptInt", Func, 0, "func(fd int, level int, opt int, value int) (err error)"},
		{"SetsockoptLinger", Func, 0, "func(fd int, level int, opt int, l *Linger) (err error)"},
		{"SetsockoptString", Func, 0, "func(fd int, level int, opt int, s string) (err error)"},
		{"SetsockoptTimeval", Func, 0, "func(fd int, level int, opt int, tv *Timeval) (err error)"},
		{"Settimeofday", Func, 0, "func(tv *Timeval) (err error)"},
		{"Setuid", Func, 0, "func(uid int) (err error)"},
		{"Setxattr", Func, 1, "func(path string, attr string, data []byte, flags int) (err error)"},
		{"Shutdown", Func, 0, "func(fd int, how int) (err error)"},
		{"SidTypeAlias", Const, 0, ""},
		{"SidTypeComputer", Const, 0, ""},
		{"SidTypeDeletedAccount", Const, 0, ""},
		{"SidTypeDomain", Const, 0, ""},
		{"SidTypeGroup", Const, 0, ""},
		{"SidTypeInvalid", Const, 0, ""},
		{"SidTypeLabel", Const, 0, ""},
		{"SidTypeUnknown", Const, 0, ""},
		{"SidTypeUser", Const, 0, ""},
		{"SidTypeWellKnownGroup", Const, 0, ""},
		{"Signal", Type, 0, ""},
		{"SizeofBpfHdr", Const, 0, ""},
		{"SizeofBpfInsn", Const, 0, ""},
		{"SizeofBpfProgram", Const, 0, ""},
		{"SizeofBpfStat", Const, 0, ""},
		{"SizeofBpfVersion", Const, 0, ""},
		{"SizeofBpfZbuf", Const, 0, ""},
		{"SizeofBpfZbufHeader", Const, 0, ""},
		{"SizeofCmsghdr", Const, 0, ""},
		{"SizeofICMPv6Filter", Const, 2, ""},
		{"SizeofIPMreq", Const, 0, ""},
		{"SizeofIPMreqn", Const, 0, ""},
		{"SizeofIPv6MTUInfo", Const, 2, ""},
		{"SizeofIPv6Mreq", Const, 0, ""},
		{"SizeofIfAddrmsg", Const, 0, ""},
		{"SizeofIfAnnounceMsghdr", Const, 1, ""},
		{"SizeofIfData", Const, 0, ""},
		{"SizeofIfInfomsg", Const, 0, ""},
		{"SizeofIfMsghdr", Const, 0, ""},
		{"SizeofIfaMsghdr", Const, 0, ""},
		{"SizeofIfmaMsghdr", Const, 0, ""},
		{"SizeofIfmaMsghdr2", Const, 0, ""},
		{"SizeofInet4Pktinfo", Const, 0, ""},
		{"SizeofInet6Pktinfo", Const, 0, ""},
		{"SizeofInotifyEvent", Const, 0, ""},
		{"SizeofLinger", Const, 0, ""},
		{"SizeofMsghdr", Const, 0, ""},
		{"SizeofNlAttr", Const, 0, ""},
		{"SizeofNlMsgerr", Const, 0, ""},
		{"SizeofNlMsghdr", Const, 0, ""},
		{"SizeofRtAttr", Const, 0, ""},
		{"SizeofRtGenmsg", Const, 0, ""},
		{"SizeofRtMetrics", Const, 0, ""},
		{"SizeofRtMsg", Const, 0, ""},
		{"SizeofRtMsghdr", Const, 0, ""},
		{"SizeofRtNexthop", Const, 0, ""},
		{"SizeofSockFilter", Const, 0, ""},
		{"SizeofSockFprog", Const, 0, ""},
		{"SizeofSockaddrAny", Const, 0, ""},
		{"SizeofSockaddrDatalink", Const, 0, ""},
		{"SizeofSockaddrInet4", Const, 0, ""},
		{"SizeofSockaddrInet6", Const, 0, ""},
		{"SizeofSockaddrLinklayer", Const, 0, ""},
		{"SizeofSockaddrNetlink", Const, 0, ""},
		{"SizeofSockaddrUnix", Const, 0, ""},
		{"SizeofTCPInfo", Const, 1, ""},
		{"SizeofUcred", Const, 0, ""},
		{"SlicePtrFromStrings", Func, 1, "func(ss []string) ([]*byte, error)"},
		{"SockFilter", Type, 0, ""},
		{"SockFilter.Code", Field, 0, ""},
		{"SockFilter.Jf", Field, 0, ""},
		{"SockFilter.Jt", Field, 0, ""},
		{"SockFilter.K", Field, 0, ""},
		{"SockFprog", Type, 0, ""},
		{"SockFprog.Filter", Field, 0, ""},
		{"SockFprog.Len", Field, 0, ""},
		{"SockFprog.Pad_cgo_0", Field, 0, ""},
		{"SockaddrDatalink", Type, 0, ""},
		{"SockaddrDatalink.Alen", Field, 0, ""},
		{"SockaddrDatalink.Data", Field, 0, ""},
		{"SockaddrDatalink.Family", Field, 0, ""},
		{"SockaddrDatalink.Index", Field, 0, ""},
		{"SockaddrDatalink.Len", Field, 0, ""},
		{"SockaddrDatalink.Nlen", Field, 0, ""},
		{"SockaddrDatalink.Slen", Field, 0, ""},
		{"SockaddrDatalink.Type", Field, 0, ""},
		{"SockaddrGen", Type, 0, ""},
		{"SockaddrInet4", Type, 0, ""},
		{"SockaddrInet4.Addr", Field, 0, ""},
		{"SockaddrInet4.Port", Field, 0, ""},
		{"SockaddrInet6", Type, 0, ""},
		{"SockaddrInet6.Addr", Field, 0, ""},
		{"SockaddrInet6.Port", Field, 0, ""},
		{"SockaddrInet6.ZoneId", Field, 0, ""},
		{"SockaddrLinklayer", Type, 0, ""},
		{"SockaddrLinklayer.Addr", Field, 0, ""},
		{"SockaddrLinklayer.Halen", Field, 0, ""},
		{"SockaddrLinklayer.Hatype", Field, 0, ""},
		{"SockaddrLinklayer.Ifindex", Field, 0, ""},
		{"SockaddrLinklayer.Pkttype", Field, 0, ""},
		{"SockaddrLinklayer.Protocol", Field, 0, ""},
		{"SockaddrNetlink", Type, 0, ""},
		{"SockaddrNetlink.Family", Field, 0, ""},
		{"SockaddrNetlink.Groups", Field, 0, ""},
		{"SockaddrNetlink.Pad", Field, 0, ""},
		{"SockaddrNetlink.Pid", Field, 0, ""},
		{"SockaddrUnix", Type, 0, ""},
		{"SockaddrUnix.Name", Field, 0, ""},
		{"Socket", Func, 0, "func(domain int, typ int, proto int) (fd int, err error)"},
		{"SocketControlMessage", Type, 0, ""},
		{"SocketControlMessage.Data", Field, 0, ""},
		{"SocketControlMessage.Header", Field, 0, ""},
		{"SocketDisableIPv6", Var, 0, ""},
		{"Socketpair", Func, 0, "func(domain int, typ int, proto int) (fd [2]int, err error)"},
		{"Splice", Func, 0, "func(rfd int, roff *int64, wfd int, woff *int64, len int, flags int) (n int64, err error)"},
		{"StartProcess", Func, 0, "func(argv0 string, argv []string, attr *ProcAttr) (pid int, handle uintptr, err error)"},
		{"StartupInfo", Type, 0, ""},
		{"StartupInfo.Cb", Field, 0, ""},
		{"StartupInfo.Desktop", Field, 0, ""},
		{"StartupInfo.FillAttribute", Field, 0, ""},
		{"StartupInfo.Flags", Field, 0, ""},
		{"StartupInfo.ShowWindow", Field, 0, ""},
		{"StartupInfo.StdErr", Field, 0, ""},
		{"StartupInfo.StdInput", Field, 0, ""},
		{"StartupInfo.StdOutput", Field, 0, ""},
		{"StartupInfo.Title", Field, 0, ""},
		{"StartupInfo.X", Field, 0, ""},
		{"StartupInfo.XCountChars", Field, 0, ""},
		{"StartupInfo.XSize", Field, 0, ""},
		{"StartupInfo.Y", Field, 0, ""},
		{"StartupInfo.YCountChars", Field, 0, ""},
		{"StartupInfo.YSize", Field, 0, ""},
		{"Stat", Func, 0, "func(path string, stat *Stat_t) (err error)"},
		{"Stat_t", Type, 0, ""},
		{"Stat_t.Atim", Field, 0, ""},
		{"Stat_t.Atim_ext", Field, 12, ""},
		{"Stat_t.Atimespec", Field, 0, ""},
		{"Stat_t.Birthtimespec", Field, 0, ""},
		{"Stat_t.Blksize", Field, 0, ""},
		{"Stat_t.Blocks", Field, 0, ""},
		{"Stat_t.Btim_ext", Field, 12, ""},
		{"Stat_t.Ctim", Field, 0, ""},
		{"Stat_t.Ctim_ext", Field, 12, ""},
		{"Stat_t.Ctimespec", Field, 0, ""},
		{"Stat_t.Dev", Field, 0, ""},
		{"Stat_t.Flags", Field, 0, ""},
		{"Stat_t.Gen", Field, 0, ""},
		{"Stat_t.Gid", Field, 0, ""},
		{"Stat_t.Ino", Field, 0, ""},
		{"Stat_t.Lspare", Field, 0, ""},
		{"Stat_t.Lspare0", Field, 2, ""},
		{"Stat_t.Lspare1", Field, 2, ""},
		{"Stat_t.Mode", Field, 0, ""},
		{"Stat_t.Mtim", Field, 0, ""},
		{"Stat_t.Mtim_ext", Field, 12, ""},
		{"Stat_t.Mtimespec", Field, 0, ""},
		{"Stat_t.Nlink", Field, 0, ""},
		{"Stat_t.Pad_cgo_0", Field, 0, ""},
		{"Stat_t.Pad_cgo_1", Field, 0, ""},
		{"Stat_t.Pad_cgo_2", Field, 0, ""},
		{"Stat_t.Padding0", Field, 12, ""},
		{"Stat_t.Padding1", Field, 12, ""},
		{"Stat_t.Qspare", Field, 0, ""},
		{"Stat_t.Rdev", Field, 0, ""},
		{"Stat_t.Size", Field, 0, ""},
		{"Stat_t.Spare", Field, 2, ""},
		{"Stat_t.Uid", Field, 0, ""},
		{"Stat_t.X__pad0", Field, 0, ""},
		{"Stat_t.X__pad1", Field, 0, ""},
		{"Stat_t.X__pad2", Field, 0, ""},
		{"Stat_t.X__st_birthtim", Field, 2, ""},
		{"Stat_t.X__st_ino", Field, 0, ""},
		{"Stat_t.X__unused", Field, 0, ""},
		{"Statfs", Func, 0, "func(path string, buf *Statfs_t) (err error)"},
		{"Statfs_t", Type, 0, ""},
		{"Statfs_t.Asyncreads", Field, 0, ""},
		{"Statfs_t.Asyncwrites", Field, 0, ""},
		{"Statfs_t.Bavail", Field, 0, ""},
		{"Statfs_t.Bfree", Field, 0, ""},
		{"Statfs_t.Blocks", Field, 0, ""},
		{"Statfs_t.Bsize", Field, 0, ""},
		{"Statfs_t.Charspare", Field, 0, ""},
		{"Statfs_t.F_asyncreads", Field, 2, ""},
		{"Statfs_t.F_asyncwrites", Field, 2, ""},
		{"Statfs_t.F_bavail", Field, 2, ""},
		{"Statfs_t.F_bfree", Field, 2, ""},
		{"Statfs_t.F_blocks", Field, 2, ""},
		{"Statfs_t.F_bsize", Field, 2, ""},
		{"Statfs_t.F_ctime", Field, 2, ""},
		{"Statfs_t.F_favail", Field, 2, ""},
		{"Statfs_t.F_ffree", Field, 2, ""},
		{"Statfs_t.F_files", Field, 2, ""},
		{"Statfs_t.F_flags", Field, 2, ""},
		{"Statfs_t.F_fsid", Field, 2, ""},
		{"Statfs_t.F_fstypename", Field, 2, ""},
		{"Statfs_t.F_iosize", Field, 2, ""},
		{"Statfs_t.F_mntfromname", Field, 2, ""},
		{"Statfs_t.F_mntfromspec", Field, 3, ""},
		{"Statfs_t.F_mntonname", Field, 2, ""},
		{"Statfs_t.F_namemax", Field, 2, ""},
		{"Statfs_t.F_owner", Field, 2, ""},
		{"Statfs_t.F_spare", Field, 2, ""},
		{"Statfs_t.F_syncreads", Field, 2, ""},
		{"Statfs_t.F_syncwrites", Field, 2, ""},
		{"Statfs_t.Ffree", Field, 0, ""},
		{"Statfs_t.Files", Field, 0, ""},
		{"Statfs_t.Flags", Field, 0, ""},
		{"Statfs_t.Frsize", Field, 0, ""},
		{"Statfs_t.Fsid", Field, 0, ""},
		{"Statfs_t.Fssubtype", Field, 0, ""},
		{"Statfs_t.Fstypename", Field, 0, ""},
		{"Statfs_t.Iosize", Field, 0, ""},
		{"Statfs_t.Mntfromname", Field, 0, ""},
		{"Statfs_t.Mntonname", Field, 0, ""},
		{"Statfs_t.Mount_info", Field, 2, ""},
		{"Statfs_t.Namelen", Field, 0, ""},
		{"Statfs_t.Namemax", Field, 0, ""},
		{"Statfs_t.Owner", Field, 0, ""},
		{"Statfs_t.Pad_cgo_0", Field, 0, ""},
		{"Statfs_t.Pad_cgo_1", Field, 2, ""},
		{"Statfs_t.Reserved", Field, 0, ""},
		{"Statfs_t.Spare", Field, 0, ""},
		{"Statfs_t.Syncreads", Field, 0, ""},
		{"Statfs_t.Syncwrites", Field, 0, ""},
		{"Statfs_t.Type", Field, 0, ""},
		{"Statfs_t.Version", Field, 0, ""},
		{"Stderr", Var, 0, ""},
		{"Stdin", Var, 0, ""},
		{"Stdout", Var, 0, ""},
		{"StringBytePtr", Func, 0, "func(s string) *byte"},
		{"StringByteSlice", Func, 0, "func(s string) []byte"},
		{"StringSlicePtr", Func, 0, "func(ss []string) []*byte"},
		{"StringToSid", Func, 0, ""},
		{"StringToUTF16", Func, 0, ""},
		{"StringToUTF16Ptr", Func, 0, ""},
		{"Symlink", Func, 0, "func(oldpath string, newpath string) (err error)"},
		{"Sync", Func, 0, "func()"},
		{"SyncFileRange", Func, 0, "func(fd int, off int64, n int64, flags int) (err error)"},
		{"SysProcAttr", Type, 0, ""},
		{"SysProcAttr.AdditionalInheritedHandles", Field, 17, ""},
		{"SysProcAttr.AmbientCaps", Field, 9, ""},
		{"SysProcAttr.CgroupFD", Field, 20, ""},
		{"SysProcAttr.Chroot", Field, 0, ""},
		{"SysProcAttr.Cloneflags", Field, 2, ""},
		{"SysProcAttr.CmdLine", Field, 0, ""},
		{"SysProcAttr.CreationFlags", Field, 1, ""},
		{"SysProcAttr.Credential", Field, 0, ""},
		{"SysProcAttr.Ctty", Field, 1, ""},
		{"SysProcAttr.Foreground", Field, 5, ""},
		{"SysProcAttr.GidMappings", Field, 4, ""},
		{"SysProcAttr.GidMappingsEnableSetgroups", Field, 5, ""},
		{"SysProcAttr.HideWindow", Field, 0, ""},
		{"SysProcAttr.Jail", Field, 21, ""},
		{"SysProcAttr.NoInheritHandles", Field, 16, ""},
		{"SysProcAttr.Noctty", Field, 0, ""},
		{"SysProcAttr.ParentProcess", Field, 17, ""},
		{"SysProcAttr.Pdeathsig", Field, 0, ""},
		{"SysProcAttr.Pgid", Field, 5, ""},
		{"SysProcAttr.PidFD", Field, 22, ""},
		{"SysProcAttr.ProcessAttributes", Field, 13, ""},
		{"SysProcAttr.Ptrace", Field, 0, ""},
		{"SysProcAttr.Setctty", Field, 0, ""},
		{"SysProcAttr.Setpgid", Field, 0, ""},
		{"SysProcAttr.Setsid", Field, 0, ""},
		{"SysProcAttr.ThreadAttributes", Field, 13, ""},
		{"SysProcAttr.Token", Field, 10, ""},
		{"SysProcAttr.UidMappings", Field, 4, ""},
		{"SysProcAttr.Unshareflags", Field, 7, ""},
		{"SysProcAttr.UseCgroupFD", Field, 20, ""},
		{"SysProcIDMap", Type, 4, ""},
		{"SysProcIDMap.ContainerID", Field, 4, ""},
		{"SysProcIDMap.HostID", Field, 4, ""},
		{"SysProcIDMap.Size", Field, 4, ""},
		{"Syscall", Func, 0, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"Syscall12", Func, 0, ""},
		{"Syscall15", Func, 0, ""},
		{"Syscall18", Func, 12, ""},
		{"Syscall6", Func, 0, "func(trap uintptr, a1 uintptr, a2 uintptr, a3 uintptr, a4 uintptr, a5 uintptr, a6 uintptr) (r1 uintptr, r2 uintptr, err Errno)"},
		{"Syscall9", Func, 0, ""},
		{"SyscallN", Func, 18, ""},
		{"Sysctl", Func, 0, ""},
		{"SysctlUint32", Func, 0, ""},
		{"Sysctlnode", Type, 2, ""},
		{"Sysctlnode.Flags", Field, 2, ""},
		{"Sysctlnode.Name", Field, 2, ""},
		{"Sysctlnode.Num", Field, 2, ""},
		{"Sysctlnode.Un", Field, 2, ""},
		{"Sysctlnode.Ver", Field, 2, ""},
		{"Sysctlnode.X__rsvd", Field, 2, ""},
		{"Sysctlnode.X_sysctl_desc", Field, 2, ""},
		{"Sysctlnode.X_sysctl_func", Field, 2, ""},
		{"Sysctlnode.X_sysctl_parent", Field, 2, ""},
		{"Sysctlnode.X_sysctl_size", Field, 2, ""},
		{"Sysinfo", Func, 0, "func(info *Sysinfo_t) (err error)"},
		{"Sysinfo_t", Type, 0, ""},
		{"Sysinfo_t.Bufferram", Field, 0, ""},
		{"Sysinfo_t.Freehigh", Field, 0, ""},
		{"Sysinfo_t.Freeram", Field, 0, ""},
		{"Sysinfo_t.Freeswap", Field, 0, ""},
		{"Sysinfo_t.Loads", Field, 0, ""},
		{"Sysinfo_t.Pad", Field, 0, ""},
		{"Sysinfo_t.Pad_cgo_0", Field, 0, ""},
		{"Sysinfo_t.Pad_cgo_1", Field, 0, ""},
		{"Sysinfo_t.Procs", Field, 0, ""},
		{"Sysinfo_t.Sharedram", Field, 0, ""},
		{"Sysinfo_t.Totalhigh", Field, 0, ""},
		{"Sysinfo_t.Totalram", Field, 0, ""},
		{"Sysinfo_t.Totalswap", Field, 0, ""},
		{"Sysinfo_t.Unit", Field, 0, ""},
		{"Sysinfo_t.Uptime", Field, 0, ""},
		{"Sysinfo_t.X_f", Field, 0, ""},
		{"Systemtime", Type, 0, ""},
		{"Systemtime.Day", Field, 0, ""},
		{"Systemtime.DayOfWeek", Field, 0, ""},
		{"Systemtime.Hour", Field, 0, ""},
		{"Systemtime.Milliseconds", Field, 0, ""},
		{"Systemtime.Minute", Field, 0, ""},
		{"Systemtime.Month", Field, 0, ""},
		{"Systemtime.Second", Field, 0, ""},
		{"Systemtime.Year", Field, 0, ""},
		{"TCGETS", Const, 0, ""},
		{"TCIFLUSH", Const, 1, ""},
		{"TCIOFLUSH", Const, 1, ""},
		{"TCOFLUSH", Const, 1, ""},
		{"TCPInfo", Type, 1, ""},
		{"TCPInfo.Advmss", Field, 1, ""},
		{"TCPInfo.Ato", Field, 1, ""},
		{"TCPInfo.Backoff", Field, 1, ""},
		{"TCPInfo.Ca_state", Field, 1, ""},
		{"TCPInfo.Fackets", Field, 1, ""},
		{"TCPInfo.Last_ack_recv", Field, 1, ""},
		{"TCPInfo.Last_ack_sent", Field, 1, ""},
		{"TCPInfo.Last_data_recv", Field, 1, ""},
		{"TCPInfo.Last_data_sent", Field, 1, ""},
		{"TCPInfo.Lost", Field, 1, ""},
		{"TCPInfo.Options", Field, 1, ""},
		{"TCPInfo.Pad_cgo_0", Field, 1, ""},
		{"TCPInfo.Pmtu", Field, 1, ""},
		{"TCPInfo.Probes", Field, 1, ""},
		{"TCPInfo.Rcv_mss", Field, 1, ""},
		{"TCPInfo.Rcv_rtt", Field, 1, ""},
		{"TCPInfo.Rcv_space", Field, 1, ""},
		{"TCPInfo.Rcv_ssthresh", Field, 1, ""},
		{"TCPInfo.Reordering", Field, 1, ""},
		{"TCPInfo.Retrans", Field, 1, ""},
		{"TCPInfo.Retransmits", Field, 1, ""},
		{"TCPInfo.Rto", Field, 1, ""},
		{"TCPInfo.Rtt", Field, 1, ""},
		{"TCPInfo.Rttvar", Field, 1, ""},
		{"TCPInfo.Sacked", Field, 1, ""},
		{"TCPInfo.Snd_cwnd", Field, 1, ""},
		{"TCPInfo.Snd_mss", Field, 1, ""},
		{"TCPInfo.Snd_ssthresh", Field, 1, ""},
		{"TCPInfo.State", Field, 1, ""},
		{"TCPInfo.Total_retrans", Field, 1, ""},
		{"TCPInfo.Unacked", Field, 1, ""},
		{"TCPKeepalive", Type, 3, ""},
		{"TCPKeepalive.Interval", Field, 3, ""},
		{"TCPKeepalive.OnOff", Field, 3, ""},
		{"TCPKeepalive.Time", Field, 3, ""},
		{"TCP_CA_NAME_MAX", Const, 0, ""},
		{"TCP_CONGCTL", Const, 1, ""},
		{"TCP_CONGESTION", Const, 0, ""},
		{"TCP_CONNECTIONTIMEOUT", Const, 0, ""},
		{"TCP_CORK", Const, 0, ""},
		{"TCP_DEFER_ACCEPT", Const, 0, ""},
		{"TCP_ENABLE_ECN", Const, 16, ""},
		{"TCP_INFO", Const, 0, ""},
		{"TCP_KEEPALIVE", Const, 0, ""},
		{"TCP_KEEPCNT", Const, 0, ""},
		{"TCP_KEEPIDLE", Const, 0, ""},
		{"TCP_KEEPINIT", Const, 1, ""},
		{"TCP_KEEPINTVL", Const, 0, ""},
		{"TCP_LINGER2", Const, 0, ""},
		{"TCP_MAXBURST", Const, 0, ""},
		{"TCP_MAXHLEN", Const, 0, ""},
		{"TCP_MAXOLEN", Const, 0, ""},
		{"TCP_MAXSEG", Const, 0, ""},
		{"TCP_MAXWIN", Const, 0, ""},
		{"TCP_MAX_SACK", Const, 0, ""},
		{"TCP_MAX_WINSHIFT", Const, 0, ""},
		{"TCP_MD5SIG", Const, 0, ""},
		{"TCP_MD5SIG_MAXKEYLEN", Const, 0, ""},
		{"TCP_MINMSS", Const, 0, ""},
		{"TCP_MINMSSOVERLOAD", Const, 0, ""},
		{"TCP_MSS", Const, 0, ""},
		{"TCP_NODELAY", Const, 0, ""},
		{"TCP_NOOPT", Const, 0, ""},
		{"TCP_NOPUSH", Const, 0, ""},
		{"TCP_NOTSENT_LOWAT", Const, 16, ""},
		{"TCP_NSTATES", Const, 1, ""},
		{"TCP_QUICKACK", Const, 0, ""},
		{"TCP_RXT_CONNDROPTIME", Const, 0, ""},
		{"TCP_RXT_FINDROP", Const, 0, ""},
		{"TCP_SACK_ENABLE", Const, 1, ""},
		{"TCP_SENDMOREACKS", Const, 16, ""},
		{"TCP_SYNCNT", Const, 0, ""},
		{"TCP_VENDOR", Const, 3, ""},
		{"TCP_WINDOW_CLAMP", Const, 0, ""},
		{"TCSAFLUSH", Const, 1, ""},
		{"TCSETS", Const, 0, ""},
		{"TF_DISCONNECT", Const, 0, ""},
		{"TF_REUSE_SOCKET", Const, 0, ""},
		{"TF_USE_DEFAULT_WORKER", Const, 0, ""},
		{"TF_USE_KERNEL_APC", Const, 0, ""},
		{"TF_USE_SYSTEM_THREAD", Const, 0, ""},
		{"TF_WRITE_BEHIND", Const, 0, ""},
		{"TH32CS_INHERIT", Const, 4, ""},
		{"TH32CS_SNAPALL", Const, 4, ""},
		{"TH32CS_SNAPHEAPLIST", Const, 4, ""},
		{"TH32CS_SNAPMODULE", Const, 4, ""},
		{"TH32CS_SNAPMODULE32", Const, 4, ""},
		{"TH32CS_SNAPPROCESS", Const, 4, ""},
		{"TH32CS_SNAPTHREAD", Const, 4, ""},
		{"TIME_ZONE_ID_DAYLIGHT", Const, 0, ""},
		{"TIME_ZONE_ID_STANDARD", Const, 0, ""},
		{"TIME_ZONE_ID_UNKNOWN", Const, 0, ""},
		{"TIOCCBRK", Const, 0, ""},
		{"TIOCCDTR", Const, 0, ""},
		{"TIOCCONS", Const, 0, ""},
		{"TIOCDCDTIMESTAMP", Const, 0, ""},
		{"TIOCDRAIN", Const, 0, ""},
		{"TIOCDSIMICROCODE", Const, 0, ""},
		{"TIOCEXCL", Const, 0, ""},
		{"TIOCEXT", Const, 0, ""},
		{"TIOCFLAG_CDTRCTS", Const, 1, ""},
		{"TIOCFLAG_CLOCAL", Const, 1, ""},
		{"TIOCFLAG_CRTSCTS", Const, 1, ""},
		{"TIOCFLAG_MDMBUF", Const, 1, ""},
		{"TIOCFLAG_PPS", Const, 1, ""},
		{"TIOCFLAG_SOFTCAR", Const, 1, ""},
		{"TIOCFLUSH", Const, 0, ""},
		{"TIOCGDEV", Const, 0, ""},
		{"TIOCGDRAINWAIT", Const, 0, ""},
		{"TIOCGETA", Const, 0, ""},
		{"TIOCGETD", Const, 0, ""},
		{"TIOCGFLAGS", Const, 1, ""},
		{"TIOCGICOUNT", Const, 0, ""},
		{"TIOCGLCKTRMIOS", Const, 0, ""},
		{"TIOCGLINED", Const, 1, ""},
		{"TIOCGPGRP", Const, 0, ""},
		{"TIOCGPTN", Const, 0, ""},
		{"TIOCGQSIZE", Const, 1, ""},
		{"TIOCGRANTPT", Const, 1, ""},
		{"TIOCGRS485", Const, 0, ""},
		{"TIOCGSERIAL", Const, 0, ""},
		{"TIOCGSID", Const, 0, ""},
		{"TIOCGSIZE", Const, 1, ""},
		{"TIOCGSOFTCAR", Const, 0, ""},
		{"TIOCGTSTAMP", Const, 1, ""},
		{"TIOCGWINSZ", Const, 0, ""},
		{"TIOCINQ", Const, 0, ""},
		{"TIOCIXOFF", Const, 0, ""},
		{"TIOCIXON", Const, 0, ""},
		{"TIOCLINUX", Const, 0, ""},
		{"TIOCMBIC", Const, 0, ""},
		{"TIOCMBIS", Const, 0, ""},
		{"TIOCMGDTRWAIT", Const, 0, ""},
		{"TIOCMGET", Const, 0, ""},
		{"TIOCMIWAIT", Const, 0, ""},
		{"TIOCMODG", Const, 0, ""},
		{"TIOCMODS", Const, 0, ""},
		{"TIOCMSDTRWAIT", Const, 0, ""},
		{"TIOCMSET", Const, 0, ""},
		{"TIOCM_CAR", Const, 0, ""},
		{"TIOCM_CD", Const, 0, ""},
		{"TIOCM_CTS", Const, 0, ""},
		{"TIOCM_DCD", Const, 0, ""},
		{"TIOCM_DSR", Const, 0, ""},
		{"TIOCM_DTR", Const, 0, ""},
		{"TIOCM_LE", Const, 0, ""},
		{"TIOCM_RI", Const, 0, ""},
		{"TIOCM_RNG", Const, 0, ""},
		{"TIOCM_RTS", Const, 0, ""},
		{"TIOCM_SR", Const, 0, ""},
		{"TIOCM_ST", Const, 0, ""},
		{"TIOCNOTTY", Const, 0, ""},
		{"TIOCNXCL", Const, 0, ""},
		{"TIOCOUTQ", Const, 0, ""},
		{"TIOCPKT", Const, 0, ""},
		{"TIOCPKT_DATA", Const, 0, ""},
		{"TIOCPKT_DOSTOP", Const, 0, ""},
		{"TIOCPKT_FLUSHREAD", Const, 0, ""},
		{"TIOCPKT_FLUSHWRITE", Const, 0, ""},
		{"TIOCPKT_IOCTL", Const, 0, ""},
		{"TIOCPKT_NOSTOP", Const, 0, ""},
		{"TIOCPKT_START", Const, 0, ""},
		{"TIOCPKT_STOP", Const, 0, ""},
		{"TIOCPTMASTER", Const, 0, ""},
		{"TIOCPTMGET", Const, 1, ""},
		{"TIOCPTSNAME", Const, 1, ""},
		{"TIOCPTYGNAME", Const, 0, ""},
		{"TIOCPTYGRANT", Const, 0, ""},
		{"TIOCPTYUNLK", Const, 0, ""},
		{"TIOCRCVFRAME", Const, 1, ""},
		{"TIOCREMOTE", Const, 0, ""},
		{"TIOCSBRK", Const, 0, ""},
		{"TIOCSCONS", Const, 0, ""},
		{"TIOCSCTTY", Const, 0, ""},
		{"TIOCSDRAINWAIT", Const, 0, ""},
		{"TIOCSDTR", Const, 0, ""},
		{"TIOCSERCONFIG", Const, 0, ""},
		{"TIOCSERGETLSR", Const, 0, ""},
		{"TIOCSERGETMULTI", Const, 0, ""},
		{"TIOCSERGSTRUCT", Const, 0, ""},
		{"TIOCSERGWILD", Const, 0, ""},
		{"TIOCSERSETMULTI", Const, 0, ""},
		{"TIOCSERSWILD", Const, 0, ""},
		{"TIOCSER_TEMT", Const, 0, ""},
		{"TIOCSETA", Const, 0, ""},
		{"TIOCSETAF", Const, 0, ""},
		{"TIOCSETAW", Const, 0, ""},
		{"TIOCSETD", Const, 0, ""},
		{"TIOCSFLAGS", Const, 1, ""},
		{"TIOCSIG", Const, 0, ""},
		{"TIOCSLCKTRMIOS", Const, 0, ""},
		{"TIOCSLINED", Const, 1, ""},
		{"TIOCSPGRP", Const, 0, ""},
		{"TIOCSPTLCK", Const, 0, ""},
		{"TIOCSQSIZE", Const, 1, ""},
		{"TIOCSRS485", Const, 0, ""},
		{"TIOCSSERIAL", Const, 0, ""},
		{"TIOCSSIZE", Const, 1, ""},
		{"TIOCSSOFTCAR", Const, 0, ""},
		{"TIOCSTART", Const, 0, ""},
		{"TIOCSTAT", Const, 0, ""},
		{"TIOCSTI", Const, 0, ""},
		{"TIOCSTOP", Const, 0, ""},
		{"TIOCSTSTAMP", Const, 1, ""},
		{"TIOCSWINSZ", Const, 0, ""},
		{"TIOCTIMESTAMP", Const, 0, ""},
		{"TIOCUCNTL", Const, 0, ""},
		{"TIOCVHANGUP", Const, 0, ""},
		{"TIOCXMTFRAME", Const, 1, ""},
		{"TOKEN_ADJUST_DEFAULT", Const, 0, ""},
		{"TOKEN_ADJUST_GROUPS", Const, 0, ""},
		{"TOKEN_ADJUST_PRIVILEGES", Const, 0, ""},
		{"TOKEN_ADJUST_SESSIONID", Const, 11, ""},
		{"TOKEN_ALL_ACCESS", Const, 0, ""},
		{"TOKEN_ASSIGN_PRIMARY", Const, 0, ""},
		{"TOKEN_DUPLICATE", Const, 0, ""},
		{"TOKEN_EXECUTE", Const, 0, ""},
		{"TOKEN_IMPERSONATE", Const, 0, ""},
		{"TOKEN_QUERY", Const, 0, ""},
		{"TOKEN_QUERY_SOURCE", Const, 0, ""},
		{"TOKEN_READ", Const, 0, ""},
		{"TOKEN_WRITE", Const, 0, ""},
		{"TOSTOP", Const, 0, ""},
		{"TRUNCATE_EXISTING", Const, 0, ""},
		{"TUNATTACHFILTER", Const, 0, ""},
		{"TUNDETACHFILTER", Const, 0, ""},
		{"TUNGETFEATURES", Const, 0, ""},
		{"TUNGETIFF", Const, 0, ""},
		{"TUNGETSNDBUF", Const, 0, ""},
		{"TUNGETVNETHDRSZ", Const, 0, ""},
		{"TUNSETDEBUG", Const, 0, ""},
		{"TUNSETGROUP", Const, 0, ""},
		{"TUNSETIFF", Const, 0, ""},
		{"TUNSETLINK", Const, 0, ""},
		{"TUNSETNOCSUM", Const, 0, ""},
		{"TUNSETOFFLOAD", Const, 0, ""},
		{"TUNSETOWNER", Const, 0, ""},
		{"TUNSETPERSIST", Const, 0, ""},
		{"TUNSETSNDBUF", Const, 0, ""},
		{"TUNSETTXFILTER", Const, 0, ""},
		{"TUNSETVNETHDRSZ", Const, 0, ""},
		{"Tee", Func, 0, "func(rfd int, wfd int, len int, flags int) (n int64, err error)"},
		{"TerminateProcess", Func, 0, ""},
		{"Termios", Type, 0, ""},
		{"Termios.Cc", Field, 0, ""},
		{"Termios.Cflag", Field, 0, ""},
		{"Termios.Iflag", Field, 0, ""},
		{"Termios.Ispeed", Field, 0, ""},
		{"Termios.Lflag", Field, 0, ""},
		{"Termios.Line", Field, 0, ""},
		{"Termios.Oflag", Field, 0, ""},
		{"Termios.Ospeed", Field, 0, ""},
		{"Termios.Pad_cgo_0", Field, 0, ""},
		{"Tgkill", Func, 0, "func(tgid int, tid int, sig Signal) (err error)"},
		{"Time", Func, 0, "func(t *Time_t) (tt Time_t, err error)"},
		{"Time_t", Type, 0, ""},
		{"Times", Func, 0, "func(tms *Tms) (ticks uintptr, err error)"},
		{"Timespec", Type, 0, ""},
		{"Timespec.Nsec", Field, 0, ""},
		{"Timespec.Pad_cgo_0", Field, 2, ""},
		{"Timespec.Sec", Field, 0, ""},
		{"TimespecToNsec", Func, 0, "func(ts Timespec) int64"},
		{"Timeval", Type, 0, ""},
		{"Timeval.Pad_cgo_0", Field, 0, ""},
		{"Timeval.Sec", Field, 0, ""},
		{"Timeval.Usec", Field, 0, ""},
		{"Timeval32", Type, 0, ""},
		{"Timeval32.Sec", Field, 0, ""},
		{"Timeval32.Usec", Field, 0, ""},
		{"TimevalToNsec", Func, 0, "func(tv Timeval) int64"},
		{"Timex", Type, 0, ""},
		{"Timex.Calcnt", Field, 0, ""},
		{"Timex.Constant", Field, 0, ""},
		{"Timex.Errcnt", Field, 0, ""},
		{"Timex.Esterror", Field, 0, ""},
		{"Timex.Freq", Field, 0, ""},
		{"Timex.Jitcnt", Field, 0, ""},
		{"Timex.Jitter", Field, 0, ""},
		{"Timex.Maxerror", Field, 0, ""},
		{"Timex.Modes", Field, 0, ""},
		{"Timex.Offset", Field, 0, ""},
		{"Timex.Pad_cgo_0", Field, 0, ""},
		{"Timex.Pad_cgo_1", Field, 0, ""},
		{"Timex.Pad_cgo_2", Field, 0, ""},
		{"Timex.Pad_cgo_3", Field, 0, ""},
		{"Timex.Ppsfreq", Field, 0, ""},
		{"Timex.Precision", Field, 0, ""},
		{"Timex.Shift", Field, 0, ""},
		{"Timex.Stabil", Field, 0, ""},
		{"Timex.Status", Field, 0, ""},
		{"Timex.Stbcnt", Field, 0, ""},
		{"Timex.Tai", Field, 0, ""},
		{"Timex.Tick", Field, 0, ""},
		{"Timex.Time", Field, 0, ""},
		{"Timex.Tolerance", Field, 0, ""},
		{"Timezoneinformation", Type, 0, ""},
		{"Timezoneinformation.Bias", Field, 0, ""},
		{"Timezoneinformation.DaylightBias", Field, 0, ""},
		{"Timezoneinformation.DaylightDate", Field, 0, ""},
		{"Timezoneinformation.DaylightName", Field, 0, ""},
		{"Timezoneinformation.StandardBias", Field, 0, ""},
		{"Timezoneinformation.StandardDate", Field, 0, ""},
		{"Timezoneinformation.StandardName", Field, 0, ""},
		{"Tms", Type, 0, ""},
		{"Tms.Cstime", Field, 0, ""},
		{"Tms.Cutime", Field, 0, ""},
		{"Tms.Stime", Field, 0, ""},
		{"Tms.Utime", Field, 0, ""},
		{"Token", Type, 0, ""},
		{"TokenAccessInformation", Const, 0, ""},
		{"TokenAuditPolicy", Const, 0, ""},
		{"TokenDefaultDacl", Const, 0, ""},
		{"TokenElevation", Const, 0, ""},
		{"TokenElevationType", Const, 0, ""},
		{"TokenGroups", Const, 0, ""},
		{"TokenGroupsAndPrivileges", Const, 0, ""},
		{"TokenHasRestrictions", Const, 0, ""},
		{"TokenImpersonationLevel", Const, 0, ""},
		{"TokenIntegrityLevel", Const, 0, ""},
		{"TokenLinkedToken", Const, 0, ""},
		{"TokenLogonSid", Const, 0, ""},
		{"TokenMandatoryPolicy", Const, 0, ""},
		{"TokenOrigin", Const, 0, ""},
		{"TokenOwner", Const, 0, ""},
		{"TokenPrimaryGroup", Const, 0, ""},
		{"TokenPrivileges", Const, 0, ""},
		{"TokenRestrictedSids", Const, 0, ""},
		{"TokenSandBoxInert", Const, 0, ""},
		{"TokenSessionId", Const, 0, ""},
		{"TokenSessionReference", Const, 0, ""},
		{"TokenSource", Const, 0, ""},
		{"TokenStatistics", Const, 0, ""},
		{"TokenType", Const, 0, ""},
		{"TokenUIAccess", Const, 0, ""},
		{"TokenUser", Const, 0, ""},
		{"TokenVirtualizationAllowed", Const, 0, ""},
		{"TokenVirtualizationEnabled", Const, 0, ""},
		{"Tokenprimarygroup", Type, 0, ""},
		{"Tokenprimarygroup.PrimaryGroup", Field, 0, ""},
		{"Tokenuser", Type, 0, ""},
		{"Tokenuser.User", Field, 0, ""},
		{"TranslateAccountName", Func, 0, ""},
		{"TranslateName", Func, 0, ""},
		{"TransmitFile", Func, 0, ""},
		{"TransmitFileBuffers", Type, 0, ""},
		{"TransmitFileBuffers.Head", Field, 0, ""},
		{"TransmitFileBuffers.HeadLength", Field, 0, ""},
		{"TransmitFileBuffers.Tail", Field, 0, ""},
		{"TransmitFileBuffers.TailLength", Field, 0, ""},
		{"Truncate", Func, 0, "func(path string, length int64) (err error)"},
		{"UNIX_PATH_MAX", Const, 12, ""},
		{"USAGE_MATCH_TYPE_AND", Const, 0, ""},
		{"USAGE_MATCH_TYPE_OR", Const, 0, ""},
		{"UTF16FromString", Func, 1, ""},
		{"UTF16PtrFromString", Func, 1, ""},
		{"UTF16ToString", Func, 0, ""},
		{"Ucred", Type, 0, ""},
		{"Ucred.Gid", Field, 0, ""},
		{"Ucred.Pid", Field, 0, ""},
		{"Ucred.Uid", Field, 0, ""},
		{"Umask", Func, 0, "func(mask int) (oldmask int)"},
		{"Uname", Func, 0, "func(buf *Utsname) (err error)"},
		{"Undelete", Func, 0, ""},
		{"UnixCredentials", Func, 0, "func(ucred *Ucred) []byte"},
		{"UnixRights", Func, 0, "func(fds ...int) []byte"},
		{"Unlink", Func, 0, "func(path string) error"},
		{"Unlinkat", Func, 0, "func(dirfd int, path string) error"},
		{"UnmapViewOfFile", Func, 0, ""},
		{"Unmount", Func, 0, "func(target string, flags int) (err error)"},
		{"Unsetenv", Func, 4, "func(key string) error"},
		{"Unshare", Func, 0, "func(flags int) (err error)"},
		{"UserInfo10", Type, 0, ""},
		{"UserInfo10.Comment", Field, 0, ""},
		{"UserInfo10.FullName", Field, 0, ""},
		{"UserInfo10.Name", Field, 0, ""},
		{"UserInfo10.UsrComment", Field, 0, ""},
		{"Ustat", Func, 0, "func(dev int, ubuf *Ustat_t) (err error)"},
		{"Ustat_t", Type, 0, ""},
		{"Ustat_t.Fname", Field, 0, ""},
		{"Ustat_t.Fpack", Field, 0, ""},
		{"Ustat_t.Pad_cgo_0", Field, 0, ""},
		{"Ustat_t.Pad_cgo_1", Field, 0, ""},
		{"Ustat_t.Tfree", Field, 0, ""},
		{"Ustat_t.Tinode", Field, 0, ""},
		{"Utimbuf", Type, 0, ""},
		{"Utimbuf.Actime", Field, 0, ""},
		{"Utimbuf.Modtime", Field, 0, ""},
		{"Utime", Func, 0, "func(path string, buf *Utimbuf) (err error)"},
		{"Utimes", Func, 0, "func(path string, tv []Timeval) (err error)"},
		{"UtimesNano", Func, 1, "func(path string, ts []Timespec) (err error)"},
		{"Utsname", Type, 0, ""},
		{"Utsname.Domainname", Field, 0, ""},
		{"Utsname.Machine", Field, 0, ""},
		{"Utsname.Nodename", Field, 0, ""},
		{"Utsname.Release", Field, 0, ""},
		{"Utsname.Sysname", Field, 0, ""},
		{"Utsname.Version", Field, 0, ""},
		{"VDISCARD", Const, 0, ""},
		{"VDSUSP", Const, 1, ""},
		{"VEOF", Const, 0, ""},
		{"VEOL", Const, 0, ""},
		{"VEOL2", Const, 0, ""},
		{"VERASE", Const, 0, ""},
		{"VERASE2", Const, 1, ""},
		{"VINTR", Const, 0, ""},
		{"VKILL", Const, 0, ""},
		{"VLNEXT", Const, 0, ""},
		{"VMIN", Const, 0, ""},
		{"VQUIT", Const, 0, ""},
		{"VREPRINT", Const, 0, ""},
		{"VSTART", Const, 0, ""},
		{"VSTATUS", Const, 1, ""},
		{"VSTOP", Const, 0, ""},
		{"VSUSP", Const, 0, ""},
		{"VSWTC", Const, 0, ""},
		{"VT0", Const, 1, ""},
		{"VT1", Const, 1, ""},
		{"VTDLY", Const, 1, ""},
		{"VTIME", Const, 0, ""},
		{"VWERASE", Const, 0, ""},
		{"VirtualLock", Func, 0, ""},
		{"VirtualUnlock", Func, 0, ""},
		{"WAIT_ABANDONED", Const, 0, ""},
		{"WAIT_FAILED", Const, 0, ""},
		{"WAIT_OBJECT_0", Const, 0, ""},
		{"WAIT_TIMEOUT", Const, 0, ""},
		{"WALL", Const, 0, ""},
		{"WALLSIG", Const, 1, ""},
		{"WALTSIG", Const, 1, ""},
		{"WCLONE", Const, 0, ""},
		{"WCONTINUED", Const, 0, ""},
		{"WCOREFLAG", Const, 0, ""},
		{"WEXITED", Const, 0, ""},
		{"WLINUXCLONE", Const, 0, ""},
		{"WNOHANG", Const, 0, ""},
		{"WNOTHREAD", Const, 0, ""},
		{"WNOWAIT", Const, 0, ""},
		{"WNOZOMBIE", Const, 1, ""},
		{"WOPTSCHECKED", Const, 1, ""},
		{"WORDSIZE", Const, 0, ""},
		{"WSABuf", Type, 0, ""},
		{"WSABuf.Buf", Field, 0, ""},
		{"WSABuf.Len", Field, 0, ""},
		{"WSACleanup", Func, 0, ""},
		{"WSADESCRIPTION_LEN", Const, 0, ""},
		{"WSAData", Type, 0, ""},
		{"WSAData.Description", Field, 0, ""},
		{"WSAData.HighVersion", Field, 0, ""},
		{"WSAData.MaxSockets", Field, 0, ""},
		{"WSAData.MaxUdpDg", Field, 0, ""},
		{"WSAData.SystemStatus", Field, 0, ""},
		{"WSAData.VendorInfo", Field, 0, ""},
		{"WSAData.Version", Field, 0, ""},
		{"WSAEACCES", Const, 2, ""},
		{"WSAECONNABORTED", Const, 9, ""},
		{"WSAECONNRESET", Const, 3, ""},
		{"WSAENOPROTOOPT", Const, 23, ""},
		{"WSAEnumProtocols", Func, 2, ""},
		{"WSAID_CONNECTEX", Var, 1, ""},
		{"WSAIoctl", Func, 0, ""},
		{"WSAPROTOCOL_LEN", Const, 2, ""},
		{"WSAProtocolChain", Type, 2, ""},
		{"WSAProtocolChain.ChainEntries", Field, 2, ""},
		{"WSAProtocolChain.ChainLen", Field, 2, ""},
		{"WSAProtocolInfo", Type, 2, ""},
		{"WSAProtocolInfo.AddressFamily", Field, 2, ""},
		{"WSAProtocolInfo.CatalogEntryId", Field, 2, ""},
		{"WSAProtocolInfo.MaxSockAddr", Field, 2, ""},
		{"WSAProtocolInfo.MessageSize", Field, 2, ""},
		{"WSAProtocolInfo.MinSockAddr", Field, 2, ""},
		{"WSAProtocolInfo.NetworkByteOrder", Field, 2, ""},
		{"WSAProtocolInfo.Protocol", Field, 2, ""},
		{"WSAProtocolInfo.ProtocolChain", Field, 2, ""},
		{"WSAProtocolInfo.ProtocolMaxOffset", Field, 2, ""},
		{"WSAProtocolInfo.ProtocolName", Field, 2, ""},
		{"WSAProtocolInfo.ProviderFlags", Field, 2, ""},
		{"WSAProtocolInfo.ProviderId", Field, 2, ""},
		{"WSAProtocolInfo.ProviderReserved", Field, 2, ""},
		{"WSAProtocolInfo.SecurityScheme", Field, 2, ""},
		{"WSAProtocolInfo.ServiceFlags1", Field, 2, ""},
		{"WSAProtocolInfo.ServiceFlags2", Field, 2, ""},
		{"WSAProtocolInfo.ServiceFlags3", Field, 2, ""},
		{"WSAProtocolInfo.ServiceFlags4", Field, 2, ""},
		{"WSAProtocolInfo.SocketType", Field, 2, ""},
		{"WSAProtocolInfo.Version", Field, 2, ""},
		{"WSARecv", Func, 0, ""},
		{"WSARecvFrom", Func, 0, ""},
		{"WSASYS_STATUS_LEN", Const, 0, ""},
		{"WSASend", Func, 0, ""},
		{"WSASendTo", Func, 0, ""},
		{"WSASendto", Func, 0, ""},
		{"WSAStartup", Func, 0, ""},
		{"WSTOPPED", Const, 0, ""},
		{"WTRAPPED", Const, 1, ""},
		{"WUNTRACED", Const, 0, ""},
		{"Wait4", Func, 0, "func(pid int, wstatus *WaitStatus, options int, rusage *Rusage) (wpid int, err error)"},
		{"WaitForSingleObject", Func, 0, ""},
		{"WaitStatus", Type, 0, ""},
		{"WaitStatus.ExitCode", Field, 0, ""},
		{"Win32FileAttributeData", Type, 0, ""},
		{"Win32FileAttributeData.CreationTime", Field, 0, ""},
		{"Win32FileAttributeData.FileAttributes", Field, 0, ""},
		{"Win32FileAttributeData.FileSizeHigh", Field, 0, ""},
		{"Win32FileAttributeData.FileSizeLow", Field, 0, ""},
		{"Win32FileAttributeData.LastAccessTime", Field, 0, ""},
		{"Win32FileAttributeData.LastWriteTime", Field, 0, ""},
		{"Win32finddata", Type, 0, ""},
		{"Win32finddata.AlternateFileName", Field, 0, ""},
		{"Win32finddata.CreationTime", Field, 0, ""},
		{"Win32finddata.FileAttributes", Field, 0, ""},
		{"Win32finddata.FileName", Field, 0, ""},
		{"Win32finddata.FileSizeHigh", Field, 0, ""},
		{"Win32finddata.FileSizeLow", Field, 0, ""},
		{"Win32finddata.LastAccessTime", Field, 0, ""},
		{"Win32finddata.LastWriteTime", Field, 0, ""},
		{"Win32finddata.Reserved0", Field, 0, ""},
		{"Win32finddata.Reserved1", Field, 0, ""},
		{"Write", Func, 0, "func(fd int, p []byte) (n int, err error)"},
		{"WriteConsole", Func, 1, ""},
		{"WriteFile", Func, 0, ""},
		{"X509_ASN_ENCODING", Const, 0, ""},
		{"XCASE", Const, 0, ""},
		{"XP1_CONNECTIONLESS", Const, 2, ""},
		{"XP1_CONNECT_DATA", Const, 2, ""},
		{"XP1_DISCONNECT_DATA", Const, 2, ""},
		{"XP1_EXPEDITED_DATA", Const, 2, ""},
		{"XP1_GRACEFUL_CLOSE", Const, 2, ""},
		{"XP1_GUARANTEED_DELIVERY", Const, 2, ""},
		{"XP1_GUARANTEED_ORDER", Const, 2, ""},
		{"XP1_IFS_HANDLES", Const, 2, ""},
		{"XP1_MESSAGE_ORIENTED", Const, 2, ""},
		{"XP1_MULTIPOINT_CONTROL_PLANE", Const, 2, ""},
		{"XP1_MULTIPOINT_DATA_PLANE", Const, 2, ""},
		{"XP1_PARTIAL_MESSAGE", Const, 2, ""},
		{"XP1_PSEUDO_STREAM", Const, 2, ""},
		{"XP1_QOS_SUPPORTED", Const, 2, ""},
		{"XP1_SAN_SUPPORT_SDP", Const, 2, ""},
		{"XP1_SUPPORT_BROADCAST", Const, 2, ""},
		{"XP1_SUPPORT_MULTIPOINT", Const, 2, ""},
		{"XP1_UNI_RECV", Const, 2, ""},
		{"XP1_UNI_SEND", Const, 2, ""},
	},
	"syscall/js": {
		{"CopyBytesToGo", Func, 0, ""},
		{"CopyBytesToJS", Func, 0, ""},
		{"Error", Type, 0, ""},
		{"Func", Type, 0, ""},
		{"FuncOf", Func, 0, ""},
		{"Global", Func, 0, ""},
		{"Null", Func, 0, ""},
		{"Type", Type, 0, ""},
		{"TypeBoolean", Const, 0, ""},
		{"TypeFunction", Const, 0, ""},
		{"TypeNull", Const, 0, ""},
		{"TypeNumber", Const, 0, ""},
		{"TypeObject", Const, 0, ""},
		{"TypeString", Const, 0, ""},
		{"TypeSymbol", Const, 0, ""},
		{"TypeUndefined", Const, 0, ""},
		{"Undefined", Func, 0, ""},
		{"Value", Type, 0, ""},
		{"ValueError", Type, 0, ""},
		{"ValueOf", Func, 0, ""},
	},
	"testing": {
		{"(*B).ArtifactDir", Method, 26, ""},
		{"(*B).Attr", Method, 25, ""},
		{"(*B).Chdir", Method, 24, ""},
		{"(*B).Cleanup", Method, 14, ""},
		{"(*B).Context", Method, 24, ""},
		{"(*B).Elapsed", Method, 20, ""},
		{"(*B).Error", Method, 0, ""},
		{"(*B).Errorf", Method, 0, ""},
		{"(*B).Fail", Method, 0, ""},
		{"(*B).FailNow", Method, 0, ""},
		{"(*B).Failed", Method, 0, ""},
		{"(*B).Fatal", Method, 0, ""},
		{"(*B).Fatalf", Method, 0, ""},
		{"(*B).Helper", Method, 9, ""},
		{"(*B).Log", Method, 0, ""},
		{"(*B).Logf", Method, 0, ""},
		{"(*B).Loop", Method, 24, ""},
		{"(*B).Name", Method, 8, ""},
		{"(*B).Output", Method, 25, ""},
		{"(*B).ReportAllocs", Method, 1, ""},
		{"(*B).ReportMetric", Method, 13, ""},
		{"(*B).ResetTimer", Method, 0, ""},
		{"(*B).Run", Method, 7, ""},
		{"(*B).RunParallel", Method, 3, ""},
		{"(*B).SetBytes", Method, 0, ""},
		{"(*B).SetParallelism", Method, 3, ""},
		{"(*B).Setenv", Method, 17, ""},
		{"(*B).Skip", Method, 1, ""},
		{"(*B).SkipNow", Method, 1, ""},
		{"(*B).Skipf", Method, 1, ""},
		{"(*B).Skipped", Method, 1, ""},
		{"(*B).StartTimer", Method, 0, ""},
		{"(*B).StopTimer", Method, 0, ""},
		{"(*B).TempDir", Method, 15, ""},
		{"(*F).Add", Method, 18, ""},
		{"(*F).ArtifactDir", Method, 26, ""},
		{"(*F).Attr", Method, 25, ""},
		{"(*F).Chdir", Method, 24, ""},
		{"(*F).Cleanup", Method, 18, ""},
		{"(*F).Context", Method, 24, ""},
		{"(*F).Error", Method, 18, ""},
		{"(*F).Errorf", Method, 18, ""},
		{"(*F).Fail", Method, 18, ""},
		{"(*F).FailNow", Method, 18, ""},
		{"(*F).Failed", Method, 18, ""},
		{"(*F).Fatal", Method, 18, ""},
		{"(*F).Fatalf", Method, 18, ""},
		{"(*F).Fuzz", Method, 18, ""},
		{"(*F).Helper", Method, 18, ""},
		{"(*F).Log", Method, 18, ""},
		{"(*F).Logf", Method, 18, ""},
		{"(*F).Name", Method, 18, ""},
		{"(*F).Output", Method, 25, ""},
		{"(*F).Setenv", Method, 18, ""},
		{"(*F).Skip", Method, 18, ""},
		{"(*F).SkipNow", Method, 18, ""},
		{"(*F).Skipf", Method, 18, ""},
		{"(*F).Skipped", Method, 18, ""},
		{"(*F).TempDir", Method, 18, ""},
		{"(*M).Run", Method, 4, ""},
		{"(*PB).Next", Method, 3, ""},
		{"(*T).ArtifactDir", Method, 26, ""},
		{"(*T).Attr", Method, 25, ""},
		{"(*T).Chdir", Method, 24, ""},
		{"(*T).Cleanup", Method, 14, ""},
		{"(*T).Context", Method, 24, ""},
		{"(*T).Deadline", Method, 15, ""},
		{"(*T).Error", Method, 0, ""},
		{"(*T).Errorf", Method, 0, ""},
		{"(*T).Fail", Method, 0, ""},
		{"(*T).FailNow", Method, 0, ""},
		{"(*T).Failed", Method, 0, ""},
		{"(*T).Fatal", Method, 0, ""},
		{"(*T).Fatalf", Method, 0, ""},
		{"(*T).Helper", Method, 9, ""},
		{"(*T).Log", Method, 0, ""},
		{"(*T).Logf", Method, 0, ""},
		{"(*T).Name", Method, 8, ""},
		{"(*T).Output", Method, 25, ""},
		{"(*T).Parallel", Method, 0, ""},
		{"(*T).Run", Method, 7, ""},
		{"(*T).Setenv", Method, 17, ""},
		{"(*T).Skip", Method, 1, ""},
		{"(*T).SkipNow", Method, 1, ""},
		{"(*T).Skipf", Method, 1, ""},
		{"(*T).Skipped", Method, 1, ""},
		{"(*T).TempDir", Method, 15, ""},
		{"(BenchmarkResult).AllocedBytesPerOp", Method, 1, ""},
		{"(BenchmarkResult).AllocsPerOp", Method, 1, ""},
		{"(BenchmarkResult).MemString", Method, 1, ""},
		{"(BenchmarkResult).NsPerOp", Method, 0, ""},
		{"(BenchmarkResult).String", Method, 0, ""},
		{"(TB).ArtifactDir", Method, 26, ""},
		{"(TB).Attr", Method, 25, ""},
		{"(TB).Chdir", Method, 24, ""},
		{"(TB).Cleanup", Method, 14, ""},
		{"(TB).Context", Method, 24, ""},
		{"(TB).Error", Method, 2, ""},
		{"(TB).Errorf", Method, 2, ""},
		{"(TB).Fail", Method, 2, ""},
		{"(TB).FailNow", Method, 2, ""},
		{"(TB).Failed", Method, 2, ""},
		{"(TB).Fatal", Method, 2, ""},
		{"(TB).Fatalf", Method, 2, ""},
		{"(TB).Helper", Method, 9, ""},
		{"(TB).Log", Method, 2, ""},
		{"(TB).Logf", Method, 2, ""},
		{"(TB).Name", Method, 8, ""},
		{"(TB).Output", Method, 25, ""},
		{"(TB).Setenv", Method, 17, ""},
		{"(TB).Skip", Method, 2, ""},
		{"(TB).SkipNow", Method, 2, ""},
		{"(TB).Skipf", Method, 2, ""},
		{"(TB).Skipped", Method, 2, ""},
		{"(TB).TempDir", Method, 15, ""},
		{"AllocsPerRun", Func, 1, "func(runs int, f func()) (avg float64)"},
		{"B", Type, 0, ""},
		{"B.N", Field, 0, ""},
		{"Benchmark", Func, 0, "func(f func(b *B)) BenchmarkResult"},
		{"BenchmarkResult", Type, 0, ""},
		{"BenchmarkResult.Bytes", Field, 0, ""},
		{"BenchmarkResult.Extra", Field, 13, ""},
		{"BenchmarkResult.MemAllocs", Field, 1, ""},
		{"BenchmarkResult.MemBytes", Field, 1, ""},
		{"BenchmarkResult.N", Field, 0, ""},
		{"BenchmarkResult.T", Field, 0, ""},
		{"Cover", Type, 2, ""},
		{"Cover.Blocks", Field, 2, ""},
		{"Cover.Counters", Field, 2, ""},
		{"Cover.CoveredPackages", Field, 2, ""},
		{"Cover.Mode", Field, 2, ""},
		{"CoverBlock", Type, 2, ""},
		{"CoverBlock.Col0", Field, 2, ""},
		{"CoverBlock.Col1", Field, 2, ""},
		{"CoverBlock.Line0", Field, 2, ""},
		{"CoverBlock.Line1", Field, 2, ""},
		{"CoverBlock.Stmts", Field, 2, ""},
		{"CoverMode", Func, 8, "func() string"},
		{"Coverage", Func, 4, "func() float64"},
		{"F", Type, 18, ""},
		{"Init", Func, 13, "func()"},
		{"InternalBenchmark", Type, 0, ""},
		{"InternalBenchmark.F", Field, 0, ""},
		{"InternalBenchmark.Name", Field, 0, ""},
		{"InternalExample", Type, 0, ""},
		{"InternalExample.F", Field, 0, ""},
		{"InternalExample.Name", Field, 0, ""},
		{"InternalExample.Output", Field, 0, ""},
		{"InternalExample.Unordered", Field, 7, ""},
		{"InternalFuzzTarget", Type, 18, ""},
		{"InternalFuzzTarget.Fn", Field, 18, ""},
		{"InternalFuzzTarget.Name", Field, 18, ""},
		{"InternalTest", Type, 0, ""},
		{"InternalTest.F", Field, 0, ""},
		{"InternalTest.Name", Field, 0, ""},
		{"M", Type, 4, ""},
		{"Main", Func, 0, "func(matchString func(pat string, str string) (bool, error), tests []InternalTest, benchmarks []InternalBenchmark, examples []InternalExample)"},
		{"MainStart", Func, 4, "func(deps testDeps, tests []InternalTest, benchmarks []InternalBenchmark, fuzzTargets []InternalFuzzTarget, examples []InternalExample) *M"},
		{"PB", Type, 3, ""},
		{"RegisterCover", Func, 2, "func(c Cover)"},
		{"RunBenchmarks", Func, 0, "func(matchString func(pat string, str string) (bool, error), benchmarks []InternalBenchmark)"},
		{"RunExamples", Func, 0, "func(matchString func(pat string, str string) (bool, error), examples []InternalExample) (ok bool)"},
		{"RunTests", Func, 0, "func(matchString func(pat string, str string) (bool, error), tests []InternalTest) (ok bool)"},
		{"Short", Func, 0, "func() bool"},
		{"T", Type, 0, ""},
		{"Testing", Func, 21, "func() bool"},
		{"Verbose", Func, 1, "func() bool"},
	},
	"testing/cryptotest": {
		{"SetGlobalRandom", Func, 26, "func(t *testing.T, seed uint64)"},
	},
	"testing/fstest": {
		{"(MapFS).Glob", Method, 16, ""},
		{"(MapFS).Lstat", Method, 25, ""},
		{"(MapFS).Open", Method, 16, ""},
		{"(MapFS).ReadDir", Method, 16, ""},
		{"(MapFS).ReadFile", Method, 16, ""},
		{"(MapFS).ReadLink", Method, 25, ""},
		{"(MapFS).Stat", Method, 16, ""},
		{"(MapFS).Sub", Method, 16, ""},
		{"MapFS", Type, 16, ""},
		{"MapFile", Type, 16, ""},
		{"MapFile.Data", Field, 16, ""},
		{"MapFile.ModTime", Field, 16, ""},
		{"MapFile.Mode", Field, 16, ""},
		{"MapFile.Sys", Field, 16, ""},
		{"TestFS", Func, 16, "func(fsys fs.FS, expected ...string) error"},
	},
	"testing/iotest": {
		{"DataErrReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"ErrReader", Func, 16, "func(err error) io.Reader"},
		{"ErrTimeout", Var, 0, ""},
		{"HalfReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"NewReadLogger", Func, 0, "func(prefix string, r io.Reader) io.Reader"},
		{"NewWriteLogger", Func, 0, "func(prefix string, w io.Writer) io.Writer"},
		{"OneByteReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"TestReader", Func, 16, "func(r io.Reader, content []byte) error"},
		{"TimeoutReader", Func, 0, "func(r io.Reader) io.Reader"},
		{"TruncateWriter", Func, 0, "func(w io.Writer, n int64) io.Writer"},
	},
	"testing/quick": {
		{"(*CheckEqualError).Error", Method, 0, ""},
		{"(*CheckError).Error", Method, 0, ""},
		{"(Generator).Generate", Method, 0, ""},
		{"(SetupError).Error", Method, 0, ""},
		{"Check", Func, 0, "func(f any, config *Config) error"},
		{"CheckEqual", Func, 0, "func(f any, g any, config *Config) error"},
		{"CheckEqualError", Type, 0, ""},
		{"CheckEqualError.CheckError", Field, 0, ""},
		{"CheckEqualError.Out1", Field, 0, ""},
		{"CheckEqualError.Out2", Field, 0, ""},
		{"CheckError", Type, 0, ""},
		{"CheckError.Count", Field, 0, ""},
		{"CheckError.In", Field, 0, ""},
		{"Config", Type, 0, ""},
		{"Config.MaxCount", Field, 0, ""},
		{"Config.MaxCountScale", Field, 0, ""},
		{"Config.Rand", Field, 0, ""},
		{"Config.Values", Field, 0, ""},
		{"Generator", Type, 0, ""},
		{"SetupError", Type, 0, ""},
		{"Value", Func, 0, "func(t reflect.Type, rand *rand.Rand) (value reflect.Value, ok bool)"},
	},
	"testing/slogtest": {
		{"Run", Func, 22, "func(t *testing.T, newHandler func(*testing.T) slog.Handler, result func(*testing.T) map[string]any)"},
		{"TestHandler", Func, 21, "func(h slog.Handler, results func() []map[string]any) error"},
	},
	"testing/synctest": {
		{"Test", Func, 25, "func(t *testing.T, f func(*testing.T))"},
		{"Wait", Func, 25, "func()"},
	},
	"text/scanner": {
		{"(*Position).IsValid", Method, 0, ""},
		{"(*Scanner).Init", Method, 0, ""},
		{"(*Scanner).IsValid", Method, 0, ""},
		{"(*Scanner).Next", Method, 0, ""},
		{"(*Scanner).Peek", Method, 0, ""},
		{"(*Scanner).Pos", Method, 0, ""},
		{"(*Scanner).Scan", Method, 0, ""},
		{"(*Scanner).TokenText", Method, 0, ""},
		{"(Position).String", Method, 0, ""},
		{"(Scanner).String", Method, 0, ""},
		{"Char", Const, 0, ""},
		{"Comment", Const, 0, ""},
		{"EOF", Const, 0, ""},
		{"Float", Const, 0, ""},
		{"GoTokens", Const, 0, ""},
		{"GoWhitespace", Const, 0, ""},
		{"Ident", Const, 0, ""},
		{"Int", Const, 0, ""},
		{"Position", Type, 0, ""},
		{"Position.Column", Field, 0, ""},
		{"Position.Filename", Field, 0, ""},
		{"Position.Line", Field, 0, ""},
		{"Position.Offset", Field, 0, ""},
		{"RawString", Const, 0, ""},
		{"ScanChars", Const, 0, ""},
		{"ScanComments", Const, 0, ""},
		{"ScanFloats", Const, 0, ""},
		{"ScanIdents", Const, 0, ""},
		{"ScanInts", Const, 0, ""},
		{"ScanRawStrings", Const, 0, ""},
		{"ScanStrings", Const, 0, ""},
		{"Scanner", Type, 0, ""},
		{"Scanner.Error", Field, 0, ""},
		{"Scanner.ErrorCount", Field, 0, ""},
		{"Scanner.IsIdentRune", Field, 4, ""},
		{"Scanner.Mode", Field, 0, ""},
		{"Scanner.Position", Field, 0, ""},
		{"Scanner.Whitespace", Field, 0, ""},
		{"SkipComments", Const, 0, ""},
		{"String", Const, 0, ""},
		{"TokenString", Func, 0, "func(tok rune) string"},
	},
	"text/tabwriter": {
		{"(*Writer).Flush", Method, 0, ""},
		{"(*Writer).Init", Method, 0, ""},
		{"(*Writer).Write", Method, 0, ""},
		{"AlignRight", Const, 0, ""},
		{"Debug", Const, 0, ""},
		{"DiscardEmptyColumns", Const, 0, ""},
		{"Escape", Const, 0, ""},
		{"FilterHTML", Const, 0, ""},
		{"NewWriter", Func, 0, "func(output io.Writer, minwidth int, tabwidth int, padding int, padchar byte, flags uint) *Writer"},
		{"StripEscape", Const, 0, ""},
		{"TabIndent", Const, 0, ""},
		{"Writer", Type, 0, ""},
	},
	"text/template": {
		{"(*Template).AddParseTree", Method, 0, ""},
		{"(*Template).Clone", Method, 0, ""},
		{"(*Template).DefinedTemplates", Method, 5, ""},
		{"(*Template).Delims", Method, 0, ""},
		{"(*Template).Execute", Method, 0, ""},
		{"(*Template).ExecuteTemplate", Method, 0, ""},
		{"(*Template).Funcs", Method, 0, ""},
		{"(*Template).Lookup", Method, 0, ""},
		{"(*Template).Name", Method, 0, ""},
		{"(*Template).New", Method, 0, ""},
		{"(*Template).Option", Method, 5, ""},
		{"(*Template).Parse", Method, 0, ""},
		{"(*Template).ParseFS", Method, 16, ""},
		{"(*Template).ParseFiles", Method, 0, ""},
		{"(*Template).ParseGlob", Method, 0, ""},
		{"(*Template).Templates", Method, 0, ""},
		{"(ExecError).Error", Method, 6, ""},
		{"(ExecError).Unwrap", Method, 13, ""},
		{"(Template).Copy", Method, 2, ""},
		{"(Template).ErrorContext", Method, 1, ""},
		{"ExecError", Type, 6, ""},
		{"ExecError.Err", Field, 6, ""},
		{"ExecError.Name", Field, 6, ""},
		{"FuncMap", Type, 0, ""},
		{"HTMLEscape", Func, 0, "func(w io.Writer, b []byte)"},
		{"HTMLEscapeString", Func, 0, "func(s string) string"},
		{"HTMLEscaper", Func, 0, "func(args ...any) string"},
		{"IsTrue", Func, 6, "func(val any) (truth bool, ok bool)"},
		{"JSEscape", Func, 0, "func(w io.Writer, b []byte)"},
		{"JSEscapeString", Func, 0, "func(s string) string"},
		{"JSEscaper", Func, 0, "func(args ...any) string"},
		{"Must", Func, 0, "func(t *Template, err error) *Template"},
		{"New", Func, 0, "func(name string) *Template"},
		{"ParseFS", Func, 16, "func(fsys fs.FS, patterns ...string) (*Template, error)"},
		{"ParseFiles", Func, 0, "func(filenames ...string) (*Template, error)"},
		{"ParseGlob", Func, 0, "func(pattern string) (*Template, error)"},
		{"Template", Type, 0, ""},
		{"Template.Tree", Field, 0, ""},
		{"URLQueryEscaper", Func, 0, "func(args ...any) string"},
	},
	"text/template/parse": {
		{"(*ActionNode).Copy", Method, 0, ""},
		{"(*ActionNode).String", Method, 0, ""},
		{"(*BoolNode).Copy", Method, 0, ""},
		{"(*BoolNode).String", Method, 0, ""},
		{"(*BranchNode).Copy", Method, 4, ""},
		{"(*BranchNode).String", Method, 0, ""},
		{"(*BreakNode).Copy", Method, 18, ""},
		{"(*BreakNode).String", Method, 18, ""},
		{"(*ChainNode).Add", Method, 1, ""},
		{"(*ChainNode).Copy", Method, 1, ""},
		{"(*ChainNode).String", Method, 1, ""},
		{"(*CommandNode).Copy", Method, 0, ""},
		{"(*CommandNode).String", Method, 0, ""},
		{"(*CommentNode).Copy", Method, 16, ""},
		{"(*CommentNode).String", Method, 16, ""},
		{"(*ContinueNode).Copy", Method, 18, ""},
		{"(*ContinueNode).String", Method, 18, ""},
		{"(*DotNode).Copy", Method, 0, ""},
		{"(*DotNode).String", Method, 0, ""},
		{"(*DotNode).Type", Method, 0, ""},
		{"(*FieldNode).Copy", Method, 0, ""},
		{"(*FieldNode).String", Method, 0, ""},
		{"(*IdentifierNode).Copy", Method, 0, ""},
		{"(*IdentifierNode).SetPos", Method, 1, ""},
		{"(*IdentifierNode).SetTree", Method, 4, ""},
		{"(*IdentifierNode).String", Method, 0, ""},
		{"(*IfNode).Copy", Method, 0, ""},
		{"(*IfNode).String", Method, 0, ""},
		{"(*ListNode).Copy", Method, 0, ""},
		{"(*ListNode).CopyList", Method, 0, ""},
		{"(*ListNode).String", Method, 0, ""},
		{"(*NilNode).Copy", Method, 1, ""},
		{"(*NilNode).String", Method, 1, ""},
		{"(*NilNode).Type", Method, 1, ""},
		{"(*NumberNode).Copy", Method, 0, ""},
		{"(*NumberNode).String", Method, 0, ""},
		{"(*PipeNode).Copy", Method, 0, ""},
		{"(*PipeNode).CopyPipe", Method, 0, ""},
		{"(*PipeNode).String", Method, 0, ""},
		{"(*RangeNode).Copy", Method, 0, ""},
		{"(*RangeNode).String", Method, 0, ""},
		{"(*StringNode).Copy", Method, 0, ""},
		{"(*StringNode).String", Method, 0, ""},
		{"(*TemplateNode).Copy", Method, 0, ""},
		{"(*TemplateNode).String", Method, 0, ""},
		{"(*TextNode).Copy", Method, 0, ""},
		{"(*TextNode).String", Method, 0, ""},
		{"(*Tree).Copy", Method, 2, ""},
		{"(*Tree).ErrorContext", Method, 1, ""},
		{"(*Tree).Parse", Method, 0, ""},
		{"(*VariableNode).Copy", Method, 0, ""},
		{"(*VariableNode).String", Method, 0, ""},
		{"(*WithNode).Copy", Method, 0, ""},
		{"(*WithNode).String", Method, 0, ""},
		{"(ActionNode).Position", Method, 1, ""},
		{"(ActionNode).Type", Method, 0, ""},
		{"(BoolNode).Position", Method, 1, ""},
		{"(BoolNode).Type", Method, 0, ""},
		{"(BranchNode).Position", Method, 1, ""},
		{"(BranchNode).Type", Method, 0, ""},
		{"(BreakNode).Position", Method, 18, ""},
		{"(BreakNode).Type", Method, 18, ""},
		{"(ChainNode).Position", Method, 1, ""},
		{"(ChainNode).Type", Method, 1, ""},
		{"(CommandNode).Position", Method, 1, ""},
		{"(CommandNode).Type", Method, 0, ""},
		{"(CommentNode).Position", Method, 16, ""},
		{"(CommentNode).Type", Method, 16, ""},
		{"(ContinueNode).Position", Method, 18, ""},
		{"(ContinueNode).Type", Method, 18, ""},
		{"(DotNode).Position", Method, 1, ""},
		{"(FieldNode).Position", Method, 1, ""},
		{"(FieldNode).Type", Method, 0, ""},
		{"(IdentifierNode).Position", Method, 1, ""},
		{"(IdentifierNode).Type", Method, 0, ""},
		{"(IfNode).Position", Method, 1, ""},
		{"(IfNode).Type", Method, 0, ""},
		{"(ListNode).Position", Method, 1, ""},
		{"(ListNode).Type", Method, 0, ""},
		{"(NilNode).Position", Method, 1, ""},
		{"(Node).Copy", Method, 0, ""},
		{"(Node).Position", Method, 1, ""},
		{"(Node).String", Method, 0, ""},
		{"(Node).Type", Method, 0, ""},
		{"(NodeType).Type", Method, 0, ""},
		{"(NumberNode).Position", Method, 1, ""},
		{"(NumberNode).Type", Method, 0, ""},
		{"(PipeNode).Position", Method, 1, ""},
		{"(PipeNode).Type", Method, 0, ""},
		{"(Pos).Position", Method, 1, ""},
		{"(RangeNode).Position", Method, 1, ""},
		{"(RangeNode).Type", Method, 0, ""},
		{"(StringNode).Position", Method, 1, ""},
		{"(StringNode).Type", Method, 0, ""},
		{"(TemplateNode).Position", Method, 1, ""},
		{"(TemplateNode).Type", Method, 0, ""},
		{"(TextNode).Position", Method, 1, ""},
		{"(TextNode).Type", Method, 0, ""},
		{"(VariableNode).Position", Method, 1, ""},
		{"(VariableNode).Type", Method, 0, ""},
		{"(WithNode).Position", Method, 1, ""},
		{"(WithNode).Type", Method, 0, ""},
		{"ActionNode", Type, 0, ""},
		{"ActionNode.Line", Field, 0, ""},
		{"ActionNode.NodeType", Field, 0, ""},
		{"ActionNode.Pipe", Field, 0, ""},
		{"ActionNode.Pos", Field, 1, ""},
		{"BoolNode", Type, 0, ""},
		{"BoolNode.NodeType", Field, 0, ""},
		{"BoolNode.Pos", Field, 1, ""},
		{"BoolNode.True", Field, 0, ""},
		{"BranchNode", Type, 0, ""},
		{"BranchNode.ElseList", Field, 0, ""},
		{"BranchNode.Line", Field, 0, ""},
		{"BranchNode.List", Field, 0, ""},
		{"BranchNode.NodeType", Field, 0, ""},
		{"BranchNode.Pipe", Field, 0, ""},
		{"BranchNode.Pos", Field, 1, ""},
		{"BreakNode", Type, 18, ""},
		{"BreakNode.Line", Field, 18, ""},
		{"BreakNode.NodeType", Field, 18, ""},
		{"BreakNode.Pos", Field, 18, ""},
		{"ChainNode", Type, 1, ""},
		{"ChainNode.Field", Field, 1, ""},
		{"ChainNode.Node", Field, 1, ""},
		{"ChainNode.NodeType", Field, 1, ""},
		{"ChainNode.Pos", Field, 1, ""},
		{"CommandNode", Type, 0, ""},
		{"CommandNode.Args", Field, 0, ""},
		{"CommandNode.NodeType", Field, 0, ""},
		{"CommandNode.Pos", Field, 1, ""},
		{"CommentNode", Type, 16, ""},
		{"CommentNode.NodeType", Field, 16, ""},
		{"CommentNode.Pos", Field, 16, ""},
		{"CommentNode.Text", Field, 16, ""},
		{"ContinueNode", Type, 18, ""},
		{"ContinueNode.Line", Field, 18, ""},
		{"ContinueNode.NodeType", Field, 18, ""},
		{"ContinueNode.Pos", Field, 18, ""},
		{"DotNode", Type, 0, ""},
		{"DotNode.NodeType", Field, 4, ""},
		{"DotNode.Pos", Field, 1, ""},
		{"FieldNode", Type, 0, ""},
		{"FieldNode.Ident", Field, 0, ""},
		{"FieldNode.NodeType", Field, 0, ""},
		{"FieldNode.Pos", Field, 1, ""},
		{"IdentifierNode", Type, 0, ""},
		{"IdentifierNode.Ident", Field, 0, ""},
		{"IdentifierNode.NodeType", Field, 0, ""},
		{"IdentifierNode.Pos", Field, 1, ""},
		{"IfNode", Type, 0, ""},
		{"IfNode.BranchNode", Field, 0, ""},
		{"IsEmptyTree", Func, 0, "func(n Node) bool"},
		{"ListNode", Type, 0, ""},
		{"ListNode.NodeType", Field, 0, ""},
		{"ListNode.Nodes", Field, 0, ""},
		{"ListNode.Pos", Field, 1, ""},
		{"Mode", Type, 16, ""},
		{"New", Func, 0, "func(name string, funcs ...map[string]any) *Tree"},
		{"NewIdentifier", Func, 0, "func(ident string) *IdentifierNode"},
		{"NilNode", Type, 1, ""},
		{"NilNode.NodeType", Field, 4, ""},
		{"NilNode.Pos", Field, 1, ""},
		{"Node", Type, 0, ""},
		{"NodeAction", Const, 0, ""},
		{"NodeBool", Const, 0, ""},
		{"NodeBreak", Const, 18, ""},
		{"NodeChain", Const, 1, ""},
		{"NodeCommand", Const, 0, ""},
		{"NodeComment", Const, 16, ""},
		{"NodeContinue", Const, 18, ""},
		{"NodeDot", Const, 0, ""},
		{"NodeField", Const, 0, ""},
		{"NodeIdentifier", Const, 0, ""},
		{"NodeIf", Const, 0, ""},
		{"NodeList", Const, 0, ""},
		{"NodeNil", Const, 1, ""},
		{"NodeNumber", Const, 0, ""},
		{"NodePipe", Const, 0, ""},
		{"NodeRange", Const, 0, ""},
		{"NodeString", Const, 0, ""},
		{"NodeTemplate", Const, 0, ""},
		{"NodeText", Const, 0, ""},
		{"NodeType", Type, 0, ""},
		{"NodeVariable", Const, 0, ""},
		{"NodeWith", Const, 0, ""},
		{"NumberNode", Type, 0, ""},
		{"NumberNode.Complex128", Field, 0, ""},
		{"NumberNode.Float64", Field, 0, ""},
		{"NumberNode.Int64", Field, 0, ""},
		{"NumberNode.IsComplex", Field, 0, ""},
		{"NumberNode.IsFloat", Field, 0, ""},
		{"NumberNode.IsInt", Field, 0, ""},
		{"NumberNode.IsUint", Field, 0, ""},
		{"NumberNode.NodeType", Field, 0, ""},
		{"NumberNode.Pos", Field, 1, ""},
		{"NumberNode.Text", Field, 0, ""},
		{"NumberNode.Uint64", Field, 0, ""},
		{"Parse", Func, 0, "func(name string, text string, leftDelim string, rightDelim string, funcs ...map[string]any) (map[string]*Tree, error)"},
		{"ParseComments", Const, 16, ""},
		{"PipeNode", Type, 0, ""},
		{"PipeNode.Cmds", Field, 0, ""},
		{"PipeNode.Decl", Field, 0, ""},
		{"PipeNode.IsAssign", Field, 11, ""},
		{"PipeNode.Line", Field, 0, ""},
		{"PipeNode.NodeType", Field, 0, ""},
		{"PipeNode.Pos", Field, 1, ""},
		{"Pos", Type, 1, ""},
		{"RangeNode", Type, 0, ""},
		{"RangeNode.BranchNode", Field, 0, ""},
		{"SkipFuncCheck", Const, 17, ""},
		{"StringNode", Type, 0, ""},
		{"StringNode.NodeType", Field, 0, ""},
		{"StringNode.Pos", Field, 1, ""},
		{"StringNode.Quoted", Field, 0, ""},
		{"StringNode.Text", Field, 0, ""},
		{"TemplateNode", Type, 0, ""},
		{"TemplateNode.Line", Field, 0, ""},
		{"TemplateNode.Name", Field, 0, ""},
		{"TemplateNode.NodeType", Field, 0, ""},
		{"TemplateNode.Pipe", Field, 0, ""},
		{"TemplateNode.Pos", Field, 1, ""},
		{"TextNode", Type, 0, ""},
		{"TextNode.NodeType", Field, 0, ""},
		{"TextNode.Pos", Field, 1, ""},
		{"TextNode.Text", Field, 0, ""},
		{"Tree", Type, 0, ""},
		{"Tree.Mode", Field, 16, ""},
		{"Tree.Name", Field, 0, ""},
		{"Tree.ParseName", Field, 1, ""},
		{"Tree.Root", Field, 0, ""},
		{"VariableNode", Type, 0, ""},
		{"VariableNode.Ident", Field, 0, ""},
		{"VariableNode.NodeType", Field, 0, ""},
		{"VariableNode.Pos", Field, 1, ""},
		{"WithNode", Type, 0, ""},
		{"WithNode.BranchNode", Field, 0, ""},
	},
	"time": {
		{"(*Location).String", Method, 0, ""},
		{"(*ParseError).Error", Method, 0, ""},
		{"(*Ticker).Reset", Method, 15, ""},
		{"(*Ticker).Stop", Method, 0, ""},
		{"(*Time).GobDecode", Method, 0, ""},
		{"(*Time).UnmarshalBinary", Method, 2, ""},
		{"(*Time).UnmarshalJSON", Method, 0, ""},
		{"(*Time).UnmarshalText", Method, 2, ""},
		{"(*Timer).Reset", Method, 1, ""},
		{"(*Timer).Stop", Method, 0, ""},
		{"(Duration).Abs", Method, 19, ""},
		{"(Duration).Hours", Method, 0, ""},
		{"(Duration).Microseconds", Method, 13, ""},
		{"(Duration).Milliseconds", Method, 13, ""},
		{"(Duration).Minutes", Method, 0, ""},
		{"(Duration).Nanoseconds", Method, 0, ""},
		{"(Duration).Round", Method, 9, ""},
		{"(Duration).Seconds", Method, 0, ""},
		{"(Duration).String", Method, 0, ""},
		{"(Duration).Truncate", Method, 9, ""},
		{"(Month).String", Method, 0, ""},
		{"(Time).Add", Method, 0, ""},
		{"(Time).AddDate", Method, 0, ""},
		{"(Time).After", Method, 0, ""},
		{"(Time).AppendBinary", Method, 24, ""},
		{"(Time).AppendFormat", Method, 5, ""},
		{"(Time).AppendText", Method, 24, ""},
		{"(Time).Before", Method, 0, ""},
		{"(Time).Clock", Method, 0, ""},
		{"(Time).Compare", Method, 20, ""},
		{"(Time).Date", Method, 0, ""},
		{"(Time).Day", Method, 0, ""},
		{"(Time).Equal", Method, 0, ""},
		{"(Time).Format", Method, 0, ""},
		{"(Time).GoString", Method, 17, ""},
		{"(Time).GobEncode", Method, 0, ""},
		{"(Time).Hour", Method, 0, ""},
		{"(Time).ISOWeek", Method, 0, ""},
		{"(Time).In", Method, 0, ""},
		{"(Time).IsDST", Method, 17, ""},
		{"(Time).IsZero", Method, 0, ""},
		{"(Time).Local", Method, 0, ""},
		{"(Time).Location", Method, 0, ""},
		{"(Time).MarshalBinary", Method, 2, ""},
		{"(Time).MarshalJSON", Method, 0, ""},
		{"(Time).MarshalText", Method, 2, ""},
		{"(Time).Minute", Method, 0, ""},
		{"(Time).Month", Method, 0, ""},
		{"(Time).Nanosecond", Method, 0, ""},
		{"(Time).Round", Method, 1, ""},
		{"(Time).Second", Method, 0, ""},
		{"(Time).String", Method, 0, ""},
		{"(Time).Sub", Method, 0, ""},
		{"(Time).Truncate", Method, 1, ""},
		{"(Time).UTC", Method, 0, ""},
		{"(Time).Unix", Method, 0, ""},
		{"(Time).UnixMicro", Method, 17, ""},
		{"(Time).UnixMilli", Method, 17, ""},
		{"(Time).UnixNano", Method, 0, ""},
		{"(Time).Weekday", Method, 0, ""},
		{"(Time).Year", Method, 0, ""},
		{"(Time).YearDay", Method, 1, ""},
		{"(Time).Zone", Method, 0, ""},
		{"(Time).ZoneBounds", Method, 19, ""},
		{"(Weekday).String", Method, 0, ""},
		{"ANSIC", Const, 0, ""},
		{"After", Func, 0, "func(d Duration) <-chan Time"},
		{"AfterFunc", Func, 0, "func(d Duration, f func()) *Timer"},
		{"April", Const, 0, ""},
		{"August", Const, 0, ""},
		{"Date", Func, 0, "func(year int, month Month, day int, hour int, min int, sec int, nsec int, loc *Location) Time"},
		{"DateOnly", Const, 20, ""},
		{"DateTime", Const, 20, ""},
		{"December", Const, 0, ""},
		{"Duration", Type, 0, ""},
		{"February", Const, 0, ""},
		{"FixedZone", Func, 0, "func(name string, offset int) *Location"},
		{"Friday", Const, 0, ""},
		{"Hour", Const, 0, ""},
		{"January", Const, 0, ""},
		{"July", Const, 0, ""},
		{"June", Const, 0, ""},
		{"Kitchen", Const, 0, ""},
		{"Layout", Const, 17, ""},
		{"LoadLocation", Func, 0, "func(name string) (*Location, error)"},
		{"LoadLocationFromTZData", Func, 10, "func(name string, data []byte) (*Location, error)"},
		{"Local", Var, 0, ""},
		{"Location", Type, 0, ""},
		{"March", Const, 0, ""},
		{"May", Const, 0, ""},
		{"Microsecond", Const, 0, ""},
		{"Millisecond", Const, 0, ""},
		{"Minute", Const, 0, ""},
		{"Monday", Const, 0, ""},
		{"Month", Type, 0, ""},
		{"Nanosecond", Const, 0, ""},
		{"NewTicker", Func, 0, "func(d Duration) *Ticker"},
		{"NewTimer", Func, 0, "func(d Duration) *Timer"},
		{"November", Const, 0, ""},
		{"Now", Func, 0, "func() Time"},
		{"October", Const, 0, ""},
		{"Parse", Func, 0, "func(layout string, value string) (Time, error)"},
		{"ParseDuration", Func, 0, "func(s string) (Duration, error)"},
		{"ParseError", Type, 0, ""},
		{"ParseError.Layout", Field, 0, ""},
		{"ParseError.LayoutElem", Field, 0, ""},
		{"ParseError.Message", Field, 0, ""},
		{"ParseError.Value", Field, 0, ""},
		{"ParseError.ValueElem", Field, 0, ""},
		{"ParseInLocation", Func, 1, "func(layout string, value string, loc *Location) (Time, error)"},
		{"RFC1123", Const, 0, ""},
		{"RFC1123Z", Const, 0, ""},
		{"RFC3339", Const, 0, ""},
		{"RFC3339Nano", Const, 0, ""},
		{"RFC822", Const, 0, ""},
		{"RFC822Z", Const, 0, ""},
		{"RFC850", Const, 0, ""},
		{"RubyDate", Const, 0, ""},
		{"Saturday", Const, 0, ""},
		{"Second", Const, 0, ""},
		{"September", Const, 0, ""},
		{"Since", Func, 0, "func(t Time) Duration"},
		{"Sleep", Func, 0, "func(d Duration)"},
		{"Stamp", Const, 0, ""},
		{"StampMicro", Const, 0, ""},
		{"StampMilli", Const, 0, ""},
		{"StampNano", Const, 0, ""},
		{"Sunday", Const, 0, ""},
		{"Thursday", Const, 0, ""},
		{"Tick", Func, 0, "func(d Duration) <-chan Time"},
		{"Ticker", Type, 0, ""},
		{"Ticker.C", Field, 0, ""},
		{"Time", Type, 0, ""},
		{"TimeOnly", Const, 20, ""},
		{"Timer", Type, 0, ""},
		{"Timer.C", Field, 0, ""},
		{"Tuesday", Const, 0, ""},
		{"UTC", Var, 0, ""},
		{"Unix", Func, 0, "func(sec int64, nsec int64) Time"},
		{"UnixDate", Const, 0, ""},
		{"UnixMicro", Func, 17, "func(usec int64) Time"},
		{"UnixMilli", Func, 17, "func(msec int64) Time"},
		{"Until", Func, 8, "func(t Time) Duration"},
		{"Wednesday", Const, 0, ""},
		{"Weekday", Type, 0, ""},
	},
	"unicode": {
		{"(SpecialCase).ToLower", Method, 0, ""},
		{"(SpecialCase).ToTitle", Method, 0, ""},
		{"(SpecialCase).ToUpper", Method, 0, ""},
		{"ASCII_Hex_Digit", Var, 0, ""},
		{"Adlam", Var, 7, ""},
		{"Ahom", Var, 5, ""},
		{"Anatolian_Hieroglyphs", Var, 5, ""},
		{"Arabic", Var, 0, ""},
		{"Armenian", Var, 0, ""},
		{"Avestan", Var, 0, ""},
		{"AzeriCase", Var, 0, ""},
		{"Balinese", Var, 0, ""},
		{"Bamum", Var, 0, ""},
		{"Bassa_Vah", Var, 4, ""},
		{"Batak", Var, 0, ""},
		{"Bengali", Var, 0, ""},
		{"Bhaiksuki", Var, 7, ""},
		{"Bidi_Control", Var, 0, ""},
		{"Bopomofo", Var, 0, ""},
		{"Brahmi", Var, 0, ""},
		{"Braille", Var, 0, ""},
		{"Buginese", Var, 0, ""},
		{"Buhid", Var, 0, ""},
		{"C", Var, 0, ""},
		{"Canadian_Aboriginal", Var, 0, ""},
		{"Carian", Var, 0, ""},
		{"CaseRange", Type, 0, ""},
		{"CaseRange.Delta", Field, 0, ""},
		{"CaseRange.Hi", Field, 0, ""},
		{"CaseRange.Lo", Field, 0, ""},
		{"CaseRanges", Var, 0, ""},
		{"Categories", Var, 0, ""},
		{"CategoryAliases", Var, 25, ""},
		{"Caucasian_Albanian", Var, 4, ""},
		{"Cc", Var, 0, ""},
		{"Cf", Var, 0, ""},
		{"Chakma", Var, 1, ""},
		{"Cham", Var, 0, ""},
		{"Cherokee", Var, 0, ""},
		{"Chorasmian", Var, 16, ""},
		{"Cn", Var, 25, ""},
		{"Co", Var, 0, ""},
		{"Common", Var, 0, ""},
		{"Coptic", Var, 0, ""},
		{"Cs", Var, 0, ""},
		{"Cuneiform", Var, 0, ""},
		{"Cypriot", Var, 0, ""},
		{"Cypro_Minoan", Var, 21, ""},
		{"Cyrillic", Var, 0, ""},
		{"Dash", Var, 0, ""},
		{"Deprecated", Var, 0, ""},
		{"Deseret", Var, 0, ""},
		{"Devanagari", Var, 0, ""},
		{"Diacritic", Var, 0, ""},
		{"Digit", Var, 0, ""},
		{"Dives_Akuru", Var, 16, ""},
		{"Dogra", Var, 13, ""},
		{"Duployan", Var, 4, ""},
		{"Egyptian_Hieroglyphs", Var, 0, ""},
		{"Elbasan", Var, 4, ""},
		{"Elymaic", Var, 14, ""},
		{"Ethiopic", Var, 0, ""},
		{"Extender", Var, 0, ""},
		{"FoldCategory", Var, 0, ""},
		{"FoldScript", Var, 0, ""},
		{"Georgian", Var, 0, ""},
		{"Glagolitic", Var, 0, ""},
		{"Gothic", Var, 0, ""},
		{"Grantha", Var, 4, ""},
		{"GraphicRanges", Var, 0, ""},
		{"Greek", Var, 0, ""},
		{"Gujarati", Var, 0, ""},
		{"Gunjala_Gondi", Var, 13, ""},
		{"Gurmukhi", Var, 0, ""},
		{"Han", Var, 0, ""},
		{"Hangul", Var, 0, ""},
		{"Hanifi_Rohingya", Var, 13, ""},
		{"Hanunoo", Var, 0, ""},
		{"Hatran", Var, 5, ""},
		{"Hebrew", Var, 0, ""},
		{"Hex_Digit", Var, 0, ""},
		{"Hiragana", Var, 0, ""},
		{"Hyphen", Var, 0, ""},
		{"IDS_Binary_Operator", Var, 0, ""},
		{"IDS_Trinary_Operator", Var, 0, ""},
		{"Ideographic", Var, 0, ""},
		{"Imperial_Aramaic", Var, 0, ""},
		{"In", Func, 2, "func(r rune, ranges ...*RangeTable) bool"},
		{"Inherited", Var, 0, ""},
		{"Inscriptional_Pahlavi", Var, 0, ""},
		{"Inscriptional_Parthian", Var, 0, ""},
		{"Is", Func, 0, "func(rangeTab *RangeTable, r rune) bool"},
		{"IsControl", Func, 0, "func(r rune) bool"},
		{"IsDigit", Func, 0, "func(r rune) bool"},
		{"IsGraphic", Func, 0, "func(r rune) bool"},
		{"IsLetter", Func, 0, "func(r rune) bool"},
		{"IsLower", Func, 0, "func(r rune) bool"},
		{"IsMark", Func, 0, "func(r rune) bool"},
		{"IsNumber", Func, 0, "func(r rune) bool"},
		{"IsOneOf", Func, 0, "func(ranges []*RangeTable, r rune) bool"},
		{"IsPrint", Func, 0, "func(r rune) bool"},
		{"IsPunct", Func, 0, "func(r rune) bool"},
		{"IsSpace", Func, 0, "func(r rune) bool"},
		{"IsSymbol", Func, 0, "func(r rune) bool"},
		{"IsTitle", Func, 0, "func(r rune) bool"},
		{"IsUpper", Func, 0, "func(r rune) bool"},
		{"Javanese", Var, 0, ""},
		{"Join_Control", Var, 0, ""},
		{"Kaithi", Var, 0, ""},
		{"Kannada", Var, 0, ""},
		{"Katakana", Var, 0, ""},
		{"Kawi", Var, 21, ""},
		{"Kayah_Li", Var, 0, ""},
		{"Kharoshthi", Var, 0, ""},
		{"Khitan_Small_Script", Var, 16, ""},
		{"Khmer", Var, 0, ""},
		{"Khojki", Var, 4, ""},
		{"Khudawadi", Var, 4, ""},
		{"L", Var, 0, ""},
		{"LC", Var, 25, ""},
		{"Lao", Var, 0, ""},
		{"Latin", Var, 0, ""},
		{"Lepcha", Var, 0, ""},
		{"Letter", Var, 0, ""},
		{"Limbu", Var, 0, ""},
		{"Linear_A", Var, 4, ""},
		{"Linear_B", Var, 0, ""},
		{"Lisu", Var, 0, ""},
		{"Ll", Var, 0, ""},
		{"Lm", Var, 0, ""},
		{"Lo", Var, 0, ""},
		{"Logical_Order_Exception", Var, 0, ""},
		{"Lower", Var, 0, ""},
		{"LowerCase", Const, 0, ""},
		{"Lt", Var, 0, ""},
		{"Lu", Var, 0, ""},
		{"Lycian", Var, 0, ""},
		{"Lydian", Var, 0, ""},
		{"M", Var, 0, ""},
		{"Mahajani", Var, 4, ""},
		{"Makasar", Var, 13, ""},
		{"Malayalam", Var, 0, ""},
		{"Mandaic", Var, 0, ""},
		{"Manichaean", Var, 4, ""},
		{"Marchen", Var, 7, ""},
		{"Mark", Var, 0, ""},
		{"Masaram_Gondi", Var, 10, ""},
		{"MaxASCII", Const, 0, ""},
		{"MaxCase", Const, 0, ""},
		{"MaxLatin1", Const, 0, ""},
		{"MaxRune", Const, 0, ""},
		{"Mc", Var, 0, ""},
		{"Me", Var, 0, ""},
		{"Medefaidrin", Var, 13, ""},
		{"Meetei_Mayek", Var, 0, ""},
		{"Mende_Kikakui", Var, 4, ""},
		{"Meroitic_Cursive", Var, 1, ""},
		{"Meroitic_Hieroglyphs", Var, 1, ""},
		{"Miao", Var, 1, ""},
		{"Mn", Var, 0, ""},
		{"Modi", Var, 4, ""},
		{"Mongolian", Var, 0, ""},
		{"Mro", Var, 4, ""},
		{"Multani", Var, 5, ""},
		{"Myanmar", Var, 0, ""},
		{"N", Var, 0, ""},
		{"Nabataean", Var, 4, ""},
		{"Nag_Mundari", Var, 21, ""},
		{"Nandinagari", Var, 14, ""},
		{"Nd", Var, 0, ""},
		{"New_Tai_Lue", Var, 0, ""},
		{"Newa", Var, 7, ""},
		{"Nko", Var, 0, ""},
		{"Nl", Var, 0, ""},
		{"No", Var, 0, ""},
		{"Noncharacter_Code_Point", Var, 0, ""},
		{"Number", Var, 0, ""},
		{"Nushu", Var, 10, ""},
		{"Nyiakeng_Puachue_Hmong", Var, 14, ""},
		{"Ogham", Var, 0, ""},
		{"Ol_Chiki", Var, 0, ""},
		{"Old_Hungarian", Var, 5, ""},
		{"Old_Italic", Var, 0, ""},
		{"Old_North_Arabian", Var, 4, ""},
		{"Old_Permic", Var, 4, ""},
		{"Old_Persian", Var, 0, ""},
		{"Old_Sogdian", Var, 13, ""},
		{"Old_South_Arabian", Var, 0, ""},
		{"Old_Turkic", Var, 0, ""},
		{"Old_Uyghur", Var, 21, ""},
		{"Oriya", Var, 0, ""},
		{"Osage", Var, 7, ""},
		{"Osmanya", Var, 0, ""},
		{"Other", Var, 0, ""},
		{"Other_Alphabetic", Var, 0, ""},
		{"Other_Default_Ignorable_Code_Point", Var, 0, ""},
		{"Other_Grapheme_Extend", Var, 0, ""},
		{"Other_ID_Continue", Var, 0, ""},
		{"Other_ID_Start", Var, 0, ""},
		{"Other_Lowercase", Var, 0, ""},
		{"Other_Math", Var, 0, ""},
		{"Other_Uppercase", Var, 0, ""},
		{"P", Var, 0, ""},
		{"Pahawh_Hmong", Var, 4, ""},
		{"Palmyrene", Var, 4, ""},
		{"Pattern_Syntax", Var, 0, ""},
		{"Pattern_White_Space", Var, 0, ""},
		{"Pau_Cin_Hau", Var, 4, ""},
		{"Pc", Var, 0, ""},
		{"Pd", Var, 0, ""},
		{"Pe", Var, 0, ""},
		{"Pf", Var, 0, ""},
		{"Phags_Pa", Var, 0, ""},
		{"Phoenician", Var, 0, ""},
		{"Pi", Var, 0, ""},
		{"Po", Var, 0, ""},
		{"Prepended_Concatenation_Mark", Var, 7, ""},
		{"PrintRanges", Var, 0, ""},
		{"Properties", Var, 0, ""},
		{"Ps", Var, 0, ""},
		{"Psalter_Pahlavi", Var, 4, ""},
		{"Punct", Var, 0, ""},
		{"Quotation_Mark", Var, 0, ""},
		{"Radical", Var, 0, ""},
		{"Range16", Type, 0, ""},
		{"Range16.Hi", Field, 0, ""},
		{"Range16.Lo", Field, 0, ""},
		{"Range16.Stride", Field, 0, ""},
		{"Range32", Type, 0, ""},
		{"Range32.Hi", Field, 0, ""},
		{"Range32.Lo", Field, 0, ""},
		{"Range32.Stride", Field, 0, ""},
		{"RangeTable", Type, 0, ""},
		{"RangeTable.LatinOffset", Field, 1, ""},
		{"RangeTable.R16", Field, 0, ""},
		{"RangeTable.R32", Field, 0, ""},
		{"Regional_Indicator", Var, 10, ""},
		{"Rejang", Var, 0, ""},
		{"ReplacementChar", Const, 0, ""},
		{"Runic", Var, 0, ""},
		{"S", Var, 0, ""},
		{"STerm", Var, 0, ""},
		{"Samaritan", Var, 0, ""},
		{"Saurashtra", Var, 0, ""},
		{"Sc", Var, 0, ""},
		{"Scripts", Var, 0, ""},
		{"Sentence_Terminal", Var, 7, ""},
		{"Sharada", Var, 1, ""},
		{"Shavian", Var, 0, ""},
		{"Siddham", Var, 4, ""},
		{"SignWriting", Var, 5, ""},
		{"SimpleFold", Func, 0, "func(r rune) rune"},
		{"Sinhala", Var, 0, ""},
		{"Sk", Var, 0, ""},
		{"Sm", Var, 0, ""},
		{"So", Var, 0, ""},
		{"Soft_Dotted", Var, 0, ""},
		{"Sogdian", Var, 13, ""},
		{"Sora_Sompeng", Var, 1, ""},
		{"Soyombo", Var, 10, ""},
		{"Space", Var, 0, ""},
		{"SpecialCase", Type, 0, ""},
		{"Sundanese", Var, 0, ""},
		{"Syloti_Nagri", Var, 0, ""},
		{"Symbol", Var, 0, ""},
		{"Syriac", Var, 0, ""},
		{"Tagalog", Var, 0, ""},
		{"Tagbanwa", Var, 0, ""},
		{"Tai_Le", Var, 0, ""},
		{"Tai_Tham", Var, 0, ""},
		{"Tai_Viet", Var, 0, ""},
		{"Takri", Var, 1, ""},
		{"Tamil", Var, 0, ""},
		{"Tangsa", Var, 21, ""},
		{"Tangut", Var, 7, ""},
		{"Telugu", Var, 0, ""},
		{"Terminal_Punctuation", Var, 0, ""},
		{"Thaana", Var, 0, ""},
		{"Thai", Var, 0, ""},
		{"Tibetan", Var, 0, ""},
		{"Tifinagh", Var, 0, ""},
		{"Tirhuta", Var, 4, ""},
		{"Title", Var, 0, ""},
		{"TitleCase", Const, 0, ""},
		{"To", Func, 0, "func(_case int, r rune) rune"},
		{"ToLower", Func, 0, "func(r rune) rune"},
		{"ToTitle", Func, 0, "func(r rune) rune"},
		{"ToUpper", Func, 0, "func(r rune) rune"},
		{"Toto", Var, 21, ""},
		{"TurkishCase", Var, 0, ""},
		{"Ugaritic", Var, 0, ""},
		{"Unified_Ideograph", Var, 0, ""},
		{"Upper", Var, 0, ""},
		{"UpperCase", Const, 0, ""},
		{"UpperLower", Const, 0, ""},
		{"Vai", Var, 0, ""},
		{"Variation_Selector", Var, 0, ""},
		{"Version", Const, 0, ""},
		{"Vithkuqi", Var, 21, ""},
		{"Wancho", Var, 14, ""},
		{"Warang_Citi", Var, 4, ""},
		{"White_Space", Var, 0, ""},
		{"Yezidi", Var, 16, ""},
		{"Yi", Var, 0, ""},
		{"Z", Var, 0, ""},
		{"Zanabazar_Square", Var, 10, ""},
		{"Zl", Var, 0, ""},
		{"Zp", Var, 0, ""},
		{"Zs", Var, 0, ""},
	},
	"unicode/utf16": {
		{"AppendRune", Func, 20, "func(a []uint16, r rune) []uint16"},
		{"Decode", Func, 0, "func(s []uint16) []rune"},
		{"DecodeRune", Func, 0, "func(r1 rune, r2 rune) rune"},
		{"Encode", Func, 0, "func(s []rune) []uint16"},
		{"EncodeRune", Func, 0, "func(r rune) (r1 rune, r2 rune)"},
		{"IsSurrogate", Func, 0, "func(r rune) bool"},
		{"RuneLen", Func, 23, "func(r rune) int"},
	},
	"unicode/utf8": {
		{"AppendRune", Func, 18, "func(p []byte, r rune) []byte"},
		{"DecodeLastRune", Func, 0, "func(p []byte) (r rune, size int)"},
		{"DecodeLastRuneInString", Func, 0, "func(s string) (r rune, size int)"},
		{"DecodeRune", Func, 0, "func(p []byte) (r rune, size int)"},
		{"DecodeRuneInString", Func, 0, "func(s string) (r rune, size int)"},
		{"EncodeRune", Func, 0, "func(p []byte, r rune) int"},
		{"FullRune", Func, 0, "func(p []byte) bool"},
		{"FullRuneInString", Func, 0, "func(s string) bool"},
		{"MaxRune", Const, 0, ""},
		{"RuneCount", Func, 0, "func(p []byte) int"},
		{"RuneCountInString", Func, 0, "func(s string) (n int)"},
		{"RuneError", Const, 0, ""},
		{"RuneLen", Func, 0, "func(r rune) int"},
		{"RuneSelf", Const, 0, ""},
		{"RuneStart", Func, 0, "func(b byte) bool"},
		{"UTFMax", Const, 0, ""},
		{"Valid", Func, 0, "func(p []byte) bool"},
		{"ValidRune", Func, 1, "func(r rune) bool"},
		{"ValidString", Func, 0, "func(s string) bool"},
	},
	"unique": {
		{"(Handle).Value", Method, 23, ""},
		{"Handle", Type, 23, ""},
		{"Make", Func, 23, "func[T comparable](value T) Handle[T]"},
	},
	"unsafe": {
		{"Add", Func, 0, ""},
		{"Alignof", Func, 0, ""},
		{"Offsetof", Func, 0, ""},
		{"Pointer", Type, 0, ""},
		{"Sizeof", Func, 0, ""},
		{"Slice", Func, 0, ""},
		{"SliceData", Func, 0, ""},
		{"String", Func, 0, ""},
		{"StringData", Func, 0, ""},
	},
	"weak": {
		{"(Pointer).Value", Method, 24, ""},
		{"Make", Func, 24, "func[T any](ptr *T) Pointer[T]"},
		{"Pointer", Type, 24, ""},
	},
}


================================================
FILE: internal/stdlib/stdlib.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:generate go run generate.go

// Package stdlib provides a table of all exported symbols in the
// standard library, along with the version at which they first
// appeared. It also provides the import graph of std packages.
package stdlib

import (
	"fmt"
	"strings"
)

type Symbol struct {
	Name    string
	Kind    Kind
	Version Version // Go version that first included the symbol
	// Signature provides the type of a function (defined only for Kind=Func).
	// Imported types are denoted as pkg.T; pkg is not fully qualified.
	// TODO(adonovan): use an unambiguous encoding that is parseable.
	//
	// Example2:
	//    func[M ~map[K]V, K comparable, V any](m M) M
	//    func(fi fs.FileInfo, link string) (*Header, error)
	Signature string // if Kind == stdlib.Func
}

// A Kind indicates the kind of a symbol:
// function, variable, constant, type, and so on.
type Kind int8

const (
	Invalid Kind = iota // Example name:
	Type                // "Buffer"
	Func                // "Println"
	Var                 // "EOF"
	Const               // "Pi"
	Field               // "Point.X"
	Method              // "(*Buffer).Grow" or "(Reader).Read"
)

func (kind Kind) String() string {
	return [...]string{
		Invalid: "invalid",
		Type:    "type",
		Func:    "func",
		Var:     "var",
		Const:   "const",
		Field:   "field",
		Method:  "method",
	}[kind]
}

// A Version represents a version of Go of the form "go1.%d".
type Version int8

// String returns a version string of the form "go1.23", without allocating.
func (v Version) String() string { return versions[v] }

var versions [30]string // (increase constant as needed)

func init() {
	for i := range versions {
		versions[i] = fmt.Sprintf("go1.%d", i)
	}
}

// HasPackage reports whether the specified package path is part of
// the standard library's public API.
func HasPackage(path string) bool {
	_, ok := PackageSymbols[path]
	return ok
}

// SplitField splits the field symbol name into type and field
// components. It must be called only on Field symbols.
//
// Example: "File.Package" -> ("File", "Package")
func (sym *Symbol) SplitField() (typename, name string) {
	if sym.Kind != Field {
		panic("not a field")
	}
	typename, name, _ = strings.Cut(sym.Name, ".")
	return
}

// SplitMethod splits the method symbol name into pointer, receiver,
// and method components. It must be called only on Method symbols.
//
// Example: "(*Buffer).Grow" -> (true, "Buffer", "Grow")
func (sym *Symbol) SplitMethod() (ptr bool, recv, name string) {
	if sym.Kind != Method {
		panic("not a method")
	}
	recv, name, _ = strings.Cut(sym.Name, ".")
	recv = recv[len("(") : len(recv)-len(")")]
	ptr = recv[0] == '*'
	if ptr {
		recv = recv[len("*"):]
	}
	return
}


================================================
FILE: internal/stdlib/testdata/nethttp.deps
================================================
internal/goarch
unsafe
internal/abi
internal/unsafeheader
internal/cpu
internal/bytealg
internal/byteorder
internal/chacha8rand
internal/coverage/rtcov
internal/godebugs
internal/goexperiment
internal/goos
internal/profilerecord
internal/runtime/atomic
internal/runtime/syscall/linux
math/bits
internal/strconv
internal/runtime/cgroup
internal/runtime/exithook
internal/runtime/gc
internal/runtime/sys
internal/runtime/gc/scan
internal/asan
internal/msan
internal/race
internal/runtime/math
internal/runtime/maps
internal/runtime/pprof/label
internal/stringslite
internal/trace/tracev2
runtime
internal/reflectlite
errors
sync/atomic
internal/sync
internal/synctest
sync
io
iter
unicode
unicode/utf8
bytes
strings
bufio
cmp
math
strconv
reflect
slices
internal/fmtsort
internal/oserror
path
internal/bisect
internal/godebug
syscall
time
io/fs
internal/filepathlite
internal/syscall/unix
internal/poll
internal/syscall/execenv
internal/testlog
os
fmt
sort
compress/flate
encoding/binary
hash
hash/crc32
compress/gzip
container/list
context
crypto
crypto/internal/fips140deps/godebug
crypto/internal/fips140
crypto/internal/fips140/alias
crypto/internal/fips140deps/byteorder
crypto/internal/fips140deps/cpu
crypto/internal/impl
crypto/internal/fips140/sha256
crypto/internal/constanttime
crypto/internal/fips140/subtle
crypto/internal/fips140/sha3
crypto/internal/fips140/sha512
crypto/internal/fips140/hmac
crypto/internal/fips140/check
crypto/internal/fips140/aes
crypto/internal/fips140deps/time
crypto/internal/entropy/v1.0.0
crypto/internal/sysrand
crypto/internal/fips140/drbg
crypto/internal/fips140/aes/gcm
crypto/fips140
crypto/internal/fips140only
crypto/subtle
crypto/cipher
crypto/internal/boring/sig
crypto/internal/boring
math/rand/v2
crypto/internal/randutil
crypto/internal/rand
math/rand
math/big
crypto/rand
crypto/aes
crypto/des
crypto/internal/fips140/nistec/fiat
crypto/internal/fips140/nistec
crypto/internal/fips140/ecdh
crypto/internal/fips140/edwards25519/field
crypto/ecdh
crypto/elliptic
crypto/internal/boring/bbig
crypto/internal/fips140/bigmod
crypto/internal/fips140/ecdsa
weak
crypto/internal/fips140cache
crypto/sha3
crypto/internal/fips140hash
crypto/sha512
internal/saferio
unicode/utf16
encoding/asn1
vendor/golang.org/x/crypto/cryptobyte/asn1
vendor/golang.org/x/crypto/cryptobyte
crypto/ecdsa
crypto/internal/fips140/edwards25519
crypto/internal/fips140/ed25519
crypto/ed25519
crypto/internal/fips140/hkdf
crypto/hkdf
crypto/hmac
crypto/internal/fips140/mlkem
crypto/mlkem
crypto/sha256
vendor/golang.org/x/crypto/internal/alias
vendor/golang.org/x/crypto/chacha20
vendor/golang.org/x/crypto/internal/poly1305
vendor/golang.org/x/sys/cpu
vendor/golang.org/x/crypto/chacha20poly1305
crypto/hpke
crypto/internal/fips140/tls12
crypto/internal/fips140/tls13
crypto/md5
crypto/rc4
crypto/internal/fips140/rsa
crypto/rsa
crypto/sha1
crypto/tls/internal/fips140tls
crypto/dsa
encoding/hex
crypto/x509/pkix
encoding/base64
encoding/pem
maps
vendor/golang.org/x/net/dns/dnsmessage
internal/nettrace
internal/singleflight
unique
net/netip
net
net/url
path/filepath
crypto/x509
crypto/tls
vendor/golang.org/x/text/transform
log/internal
log
vendor/golang.org/x/text/unicode/bidi
vendor/golang.org/x/text/secure/bidirule
vendor/golang.org/x/text/unicode/norm
vendor/golang.org/x/net/idna
net/textproto
vendor/golang.org/x/net/http/httpguts
vendor/golang.org/x/net/http/httpproxy
vendor/golang.org/x/net/http2/hpack
mime
mime/quotedprintable
mime/multipart
net/http/httptrace
net/http/internal
net/http/internal/ascii
net/http/internal/httpcommon
net/http


================================================
FILE: internal/stdlib/testdata/nethttp.imports
================================================
bufio
bytes
compress/flate
compress/gzip
container/list
context
crypto/rand
crypto/tls
encoding/base64
encoding/binary
errors
fmt
vendor/golang.org/x/net/http/httpguts
vendor/golang.org/x/net/http/httpproxy
vendor/golang.org/x/net/http2/hpack
vendor/golang.org/x/net/idna
internal/godebug
io
io/fs
log
maps
math
math/bits
math/rand
mime
mime/multipart
net
net/http/httptrace
net/http/internal
net/http/internal/ascii
net/http/internal/httpcommon
net/textproto
net/url
os
path
path/filepath
reflect
runtime
slices
sort
strconv
strings
sync
sync/atomic
time
unicode
unicode/utf8
unsafe


================================================
FILE: internal/testenv/exec.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testenv

import (
	"context"
	"flag"
	"os"
	"os/exec"
	"reflect"
	"runtime"
	"strconv"
	"sync"
	"testing"
	"time"
)

// HasExec reports whether the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
func HasExec() bool {
	switch runtime.GOOS {
	case "aix",
		"android",
		"darwin",
		"dragonfly",
		"freebsd",
		"illumos",
		"linux",
		"netbsd",
		"openbsd",
		"plan9",
		"solaris",
		"windows":
		// Known OS that isn't ios or wasm; assume that exec works.
		return true

	case "ios", "js", "wasip1":
		// ios has an exec syscall but on real iOS devices it might return a
		// permission error. In an emulated environment (such as a Corellium host)
		// it might succeed, so try it and find out.
		//
		// As of 2023-04-19 wasip1 and js don't have exec syscalls at all, but we
		// may as well use the same path so that this branch can be tested without
		// an ios environment.
		fallthrough

	default:
		tryExecOnce.Do(func() {
			exe, err := os.Executable()
			if err != nil {
				return
			}
			if flag.Lookup("test.list") == nil {
				// We found the executable, but we don't know how to run it in a way
				// that should succeed without side-effects. Just forget it.
				return
			}
			// We know that a test executable exists and can run, because we're
			// running it now. Use it to check for overall exec support, but be sure
			// to remove any environment variables that might trigger non-default
			// behavior in a custom TestMain.
			cmd := exec.Command(exe, "-test.list=^$")
			cmd.Env = []string{}
			if err := cmd.Run(); err == nil {
				tryExecOk = true
			}
		})
		return tryExecOk
	}
}

var (
	tryExecOnce sync.Once
	tryExecOk   bool
)

// NeedsExec checks that the current system can start new processes
// using os.StartProcess or (more commonly) exec.Command.
// If not, NeedsExec calls t.Skip with an explanation.
func NeedsExec(t testing.TB) {
	if !HasExec() {
		t.Skipf("skipping test: cannot exec subprocess on %s/%s", runtime.GOOS, runtime.GOARCH)
	}
}

// CommandContext is like exec.CommandContext, but:
//   - skips t if the platform does not support os/exec,
//   - if supported, sends SIGQUIT instead of SIGKILL in its Cancel function
//   - if the test has a deadline, adds a Context timeout and (if supported) WaitDelay
//     for an arbitrary grace period before the test's deadline expires,
//   - if Cmd has the Cancel field, fails the test if the command is canceled
//     due to the test's deadline, and
//   - sets a Cleanup function that verifies that the test did not leak a subprocess.
func CommandContext(t testing.TB, ctx context.Context, name string, args ...string) *exec.Cmd {
	t.Helper()
	NeedsExec(t)

	var (
		cancelCtx   context.CancelFunc
		gracePeriod time.Duration // unlimited unless the test has a deadline (to allow for interactive debugging)
	)

	if td, ok := Deadline(t); ok {
		// Start with a minimum grace period, just long enough to consume the
		// output of a reasonable program after it terminates.
		gracePeriod = 100 * time.Millisecond
		if s := os.Getenv("GO_TEST_TIMEOUT_SCALE"); s != "" {
			scale, err := strconv.Atoi(s)
			if err != nil {
				t.Fatalf("invalid GO_TEST_TIMEOUT_SCALE: %v", err)
			}
			gracePeriod *= time.Duration(scale)
		}

		// If time allows, increase the termination grace period to 5% of the
		// test's remaining time.
		testTimeout := time.Until(td)
		if gp := testTimeout / 20; gp > gracePeriod {
			gracePeriod = gp
		}

		// When we run commands that execute subprocesses, we want to reserve two
		// grace periods to clean up: one for the delay between the first
		// termination signal being sent (via the Cancel callback when the Context
		// expires) and the process being forcibly terminated (via the WaitDelay
		// field), and a second one for the delay between the process being
		// terminated and the test logging its output for debugging.
		//
		// (We want to ensure that the test process itself has enough time to
		// log the output before it is also terminated.)
		cmdTimeout := testTimeout - 2*gracePeriod

		if cd, ok := ctx.Deadline(); !ok || time.Until(cd) > cmdTimeout {
			// Either ctx doesn't have a deadline, or its deadline would expire
			// after (or too close before) the test has already timed out.
			// Add a shorter timeout so that the test will produce useful output.
			ctx, cancelCtx = context.WithTimeout(ctx, cmdTimeout)
		}
	}

	cmd := exec.CommandContext(ctx, name, args...)

	// Use reflection to set the Cancel and WaitDelay fields, if present.
	// TODO(bcmills): When we no longer support Go versions below 1.20,
	// remove the use of reflect and assume that the fields are always present.
	rc := reflect.ValueOf(cmd).Elem()

	if rCancel := rc.FieldByName("Cancel"); rCancel.IsValid() {
		rCancel.Set(reflect.ValueOf(func() error {
			if cancelCtx != nil && ctx.Err() == context.DeadlineExceeded {
				// The command timed out due to running too close to the test's deadline
				// (because we specifically set a shorter Context deadline for that
				// above). There is no way the test did that intentionally — it's too
				// close to the wire! — so mark it as a test failure. That way, if the
				// test expects the command to fail for some other reason, it doesn't
				// have to distinguish between that reason and a timeout.
				t.Errorf("test timed out while running command: %v", cmd)
			} else {
				// The command is being terminated due to ctx being canceled, but
				// apparently not due to an explicit test deadline that we added.
				// Log that information in case it is useful for diagnosing a failure,
				// but don't actually fail the test because of it.
				t.Logf("%v: terminating command: %v", ctx.Err(), cmd)
			}
			return cmd.Process.Signal(Sigquit)
		}))
	}

	if rWaitDelay := rc.FieldByName("WaitDelay"); rWaitDelay.IsValid() {
		rWaitDelay.Set(reflect.ValueOf(gracePeriod))
	}

	t.Cleanup(func() {
		if cancelCtx != nil {
			cancelCtx()
		}
		if cmd.Process != nil && cmd.ProcessState == nil {
			t.Errorf("command was started, but test did not wait for it to complete: %v", cmd)
		}
	})

	return cmd
}

// Command is like exec.Command, but applies the same changes as
// testenv.CommandContext (with a default Context).
func Command(t testing.TB, name string, args ...string) *exec.Cmd {
	t.Helper()
	return CommandContext(t, context.Background(), name, args...)
}


================================================
FILE: internal/testenv/testenv.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testenv contains helper functions for skipping tests
// based on which tools are present in the environment.
package testenv

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"go/build"
	"log"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"runtime/debug"
	"strings"
	"sync"
	"testing"
	"time"

	"golang.org/x/mod/modfile"
	"golang.org/x/tools/internal/gocommand"
)

// packageMainIsDevel reports whether the module containing package main
// is a development version (if module information is available).
func packageMainIsDevel() bool {
	info, ok := debug.ReadBuildInfo()
	if !ok {
		// Most test binaries currently lack build info, but this should become more
		// permissive once https://golang.org/issue/33976 is fixed.
		return true
	}

	// Note: info.Main.Version describes the version of the module containing
	// package main, not the version of “the main module”.
	// See https://golang.org/issue/33975.
	return info.Main.Version == "(devel)"
}

var checkGoBuild struct {
	once sync.Once
	err  error
}

// HasTool reports an error if the required tool is not available in PATH.
//
// For certain tools, it checks that the tool executable is correct.
func HasTool(tool string) error {
	if tool == "cgo" {
		enabled, err := cgoEnabled(false)
		if err != nil {
			return fmt.Errorf("checking cgo: %v", err)
		}
		if !enabled {
			return fmt.Errorf("cgo not enabled")
		}
		return nil
	}

	_, err := exec.LookPath(tool)
	if err != nil {
		return err
	}

	switch tool {
	case "patch":
		// check that the patch tools supports the -o argument
		temp, err := os.CreateTemp("", "patch-test")
		if err != nil {
			return err
		}
		temp.Close()
		defer os.Remove(temp.Name())
		cmd := exec.Command(tool, "-o", temp.Name())
		if err := cmd.Run(); err != nil {
			return err
		}

	case "go":
		checkGoBuild.once.Do(func() {
			if runtime.GOROOT() != "" {
				// Ensure that the 'go' command found by exec.LookPath is from the correct
				// GOROOT. Otherwise, 'some/path/go test ./...' will test against some
				// version of the 'go' binary other than 'some/path/go', which is almost
				// certainly not what the user intended.
				out, err := exec.Command(tool, "env", "GOROOT").Output()
				if err != nil {
					if exit, ok := err.(*exec.ExitError); ok && len(exit.Stderr) > 0 {
						err = fmt.Errorf("%w\nstderr:\n%s)", err, exit.Stderr)
					}
					checkGoBuild.err = err
					return
				}
				GOROOT := strings.TrimSpace(string(out))
				if GOROOT != runtime.GOROOT() {
					checkGoBuild.err = fmt.Errorf("'go env GOROOT' does not match runtime.GOROOT:\n\tgo env: %s\n\tGOROOT: %s", GOROOT, runtime.GOROOT())
					return
				}
			}

			dir, err := os.MkdirTemp("", "testenv-*")
			if err != nil {
				checkGoBuild.err = err
				return
			}
			defer os.RemoveAll(dir)

			mainGo := filepath.Join(dir, "main.go")
			if err := os.WriteFile(mainGo, []byte("package main\nfunc main() {}\n"), 0644); err != nil {
				checkGoBuild.err = err
				return
			}
			cmd := exec.Command("go", "build", "-o", os.DevNull, mainGo)
			cmd.Dir = dir
			if out, err := cmd.CombinedOutput(); err != nil {
				if len(out) > 0 {
					checkGoBuild.err = fmt.Errorf("%v: %v\n%s", cmd, err, out)
				} else {
					checkGoBuild.err = fmt.Errorf("%v: %v", cmd, err)
				}
			}
		})
		if checkGoBuild.err != nil {
			return checkGoBuild.err
		}

	case "diff":
		// Check that diff is the GNU or Apple version, needed for the -u argument and
		// to report missing newlines at the end of files.
		out, err := exec.Command(tool, "-version").Output()
		if err != nil {
			out, _ = exec.Command(tool, "--version").Output()
			if bytes.Contains(out, []byte("Apple diff")) {
				return nil
			}
			return err
		}
		if !bytes.Contains(out, []byte("GNU diffutils")) {
			return fmt.Errorf("diff is not the GNU version")
		}
	}

	return nil
}

func cgoEnabled(bypassEnvironment bool) (bool, error) {
	cmd := exec.Command("go", "env", "CGO_ENABLED")
	if bypassEnvironment {
		cmd.Env = append(os.Environ(), "CGO_ENABLED=")
	}
	out, err := cmd.Output()
	if err != nil {
		if exit, ok := err.(*exec.ExitError); ok && len(exit.Stderr) > 0 {
			err = fmt.Errorf("%w\nstderr:\n%s", err, exit.Stderr)
		}
		return false, err
	}
	enabled := strings.TrimSpace(string(out))
	return enabled == "1", nil
}

func allowMissingTool(tool string) bool {
	switch runtime.GOOS {
	case "aix", "darwin", "dragonfly", "freebsd", "illumos", "linux", "netbsd", "openbsd", "plan9", "solaris", "windows":
		// Known non-mobile OS. Expect a reasonably complete environment.
	default:
		return true
	}

	switch tool {
	case "cgo":
		if strings.HasSuffix(os.Getenv("GO_BUILDER_NAME"), "-nocgo") {
			// Explicitly disabled on -nocgo builders.
			return true
		}
		if enabled, err := cgoEnabled(true); err == nil && !enabled {
			// No platform support.
			return true
		}
	case "go":
		if os.Getenv("GO_BUILDER_NAME") == "illumos-amd64-joyent" {
			// Work around a misconfigured builder (see https://golang.org/issue/33950).
			return true
		}
	case "diff":
		if os.Getenv("GO_BUILDER_NAME") != "" {
			return true
		}
	case "patch":
		if os.Getenv("GO_BUILDER_NAME") != "" {
			return true
		}
	}

	// If a developer is actively working on this test, we expect them to have all
	// of its dependencies installed. However, if it's just a dependency of some
	// other module (for example, being run via 'go test all'), we should be more
	// tolerant of unusual environments.
	return !packageMainIsDevel()
}

// NeedsTool skips t if the named tool is not present in the path.
// As a special case, "cgo" means "go" is present and can compile cgo programs.
func NeedsTool(t testing.TB, tool string) {
	err := HasTool(tool)
	if err == nil {
		return
	}

	t.Helper()
	if allowMissingTool(tool) {
		// TODO(adonovan): if we skip because of (e.g.)
		// mismatched go env GOROOT and runtime.GOROOT, don't
		// we risk some users not getting the coverage they expect?
		// bcmills notes: this shouldn't be a concern as of CL 404134 (Go 1.19).
		// We could probably safely get rid of that GOPATH consistency
		// check entirely at this point.
		t.Skipf("skipping because %s tool not available: %v", tool, err)
	} else {
		t.Fatalf("%s tool not available: %v", tool, err)
	}
}

// NeedsGoPackages skips t if the go/packages driver (or 'go' tool) implied by
// the current process environment is not present in the path.
func NeedsGoPackages(t testing.TB) {
	t.Helper()

	tool := os.Getenv("GOPACKAGESDRIVER")
	switch tool {
	case "off":
		// "off" forces go/packages to use the go command.
		tool = "go"
	case "":
		if _, err := exec.LookPath("gopackagesdriver"); err == nil {
			tool = "gopackagesdriver"
		} else {
			tool = "go"
		}
	}

	NeedsTool(t, tool)
}

// NeedsGoPackagesEnv skips t if the go/packages driver (or 'go' tool) implied
// by env is not present in the path.
func NeedsGoPackagesEnv(t testing.TB, env []string) {
	t.Helper()

	for _, v := range env {
		if after, ok := strings.CutPrefix(v, "GOPACKAGESDRIVER="); ok {
			tool := after
			if tool == "off" {
				NeedsTool(t, "go")
			} else {
				NeedsTool(t, tool)
			}
			return
		}
	}

	NeedsGoPackages(t)
}

// NeedsGoBuild skips t if the current system can't build programs with “go build”
// and then run them with os.StartProcess or exec.Command.
// Android doesn't have the userspace go build needs to run,
// and js/wasm doesn't support running subprocesses.
func NeedsGoBuild(t testing.TB) {
	t.Helper()

	// This logic was derived from internal/testing.HasGoBuild and
	// may need to be updated as that function evolves.

	NeedsTool(t, "go")
}

// NeedsDefaultImporter skips t if the test uses the default importer,
// returned by [go/importer.Default].
func NeedsDefaultImporter(t testing.TB) {
	t.Helper()
	// The default importer may call `go list`
	// (in src/internal/exportdata/exportdata.go:lookupGorootExport),
	// so check for the go tool.
	NeedsTool(t, "go")
}

// ExitIfSmallMachine emits a helpful diagnostic and calls os.Exit(0) if the
// current machine is a builder known to have scarce resources.
//
// It should be called from within a TestMain function.
func ExitIfSmallMachine() {
	switch b := os.Getenv("GO_BUILDER_NAME"); b {
	case "linux-arm-scaleway":
		// "linux-arm" was renamed to "linux-arm-scaleway" in CL 303230.
		fmt.Fprintln(os.Stderr, "skipping test: linux-arm-scaleway builder lacks sufficient memory (https://golang.org/issue/32834)")
	case "plan9-arm":
		fmt.Fprintln(os.Stderr, "skipping test: plan9-arm builder lacks sufficient memory (https://golang.org/issue/38772)")
	case "netbsd-arm-bsiegert", "netbsd-arm64-bsiegert":
		// As of 2021-06-02, these builders are running with GO_TEST_TIMEOUT_SCALE=10,
		// and there is only one of each. We shouldn't waste those scarce resources
		// running very slow tests.
		fmt.Fprintf(os.Stderr, "skipping test: %s builder is very slow\n", b)
	case "dragonfly-amd64":
		// As of 2021-11-02, this builder is running with GO_TEST_TIMEOUT_SCALE=2,
		// and seems to have unusually slow disk performance.
		fmt.Fprintln(os.Stderr, "skipping test: dragonfly-amd64 has slow disk (https://golang.org/issue/45216)")
	case "linux-riscv64-unmatched":
		// As of 2021-11-03, this builder is empirically not fast enough to run
		// gopls tests. Ideally we should make the tests faster in short mode
		// and/or fix them to not assume arbitrary deadlines.
		// For now, we'll skip them instead.
		fmt.Fprintf(os.Stderr, "skipping test: %s builder is too slow (https://golang.org/issue/49321)\n", b)
	default:
		switch runtime.GOOS {
		case "android", "ios":
			fmt.Fprintf(os.Stderr, "skipping test: assuming that %s is resource-constrained\n", runtime.GOOS)
		default:
			return
		}
	}
	os.Exit(0)
}

// Go1Point returns the x in Go 1.x.
func Go1Point() int {
	for i := len(build.Default.ReleaseTags) - 1; i >= 0; i-- {
		var version int
		if _, err := fmt.Sscanf(build.Default.ReleaseTags[i], "go1.%d", &version); err != nil {
			continue
		}
		return version
	}
	panic("bad release tags")
}

// NeedsGoCommand1Point skips t if the ambient go command version in the PATH
// of the current process is older than 1.x.
//
// NeedsGoCommand1Point memoizes the result of running the go command, so
// should be called after all mutations of PATH.
func NeedsGoCommand1Point(t testing.TB, x int) {
	NeedsTool(t, "go")
	go1point, err := goCommand1Point()
	if err != nil {
		panic(fmt.Sprintf("unable to determine go version: %v", err))
	}
	if go1point < x {
		t.Helper()
		t.Skipf("go command is version 1.%d, older than required 1.%d", go1point, x)
	}
}

var (
	goCommand1PointOnce sync.Once
	goCommand1Point_    int
	goCommand1PointErr  error
)

func goCommand1Point() (int, error) {
	goCommand1PointOnce.Do(func() {
		goCommand1Point_, goCommand1PointErr = gocommand.GoVersion(context.Background(), gocommand.Invocation{}, new(gocommand.Runner))
	})
	return goCommand1Point_, goCommand1PointErr
}

// NeedsGo1Point skips t if the Go version used to run the test is older than
// 1.x.
func NeedsGo1Point(t testing.TB, x int) {
	if Go1Point() < x {
		t.Helper()
		t.Skipf("running Go version %q is version 1.%d, older than required 1.%d", runtime.Version(), Go1Point(), x)
	}
}

// SkipAfterGoCommand1Point skips t if the ambient go command version in the PATH of
// the current process is newer than 1.x.
//
// SkipAfterGoCommand1Point memoizes the result of running the go command, so
// should be called after any mutation of PATH.
func SkipAfterGoCommand1Point(t testing.TB, x int) {
	NeedsTool(t, "go")
	go1point, err := goCommand1Point()
	if err != nil {
		panic(fmt.Sprintf("unable to determine go version: %v", err))
	}
	if go1point > x {
		t.Helper()
		t.Skipf("go command is version 1.%d, newer than maximum 1.%d", go1point, x)
	}
}

// SkipAfterGo1Point skips t if the Go version used to run the test is newer than
// 1.x.
func SkipAfterGo1Point(t testing.TB, x int) {
	if Go1Point() > x {
		t.Helper()
		t.Skipf("running Go version %q is version 1.%d, newer than maximum 1.%d", runtime.Version(), Go1Point(), x)
	}
}

// NeedsLocalhostNet skips t if networking does not work for ports opened
// with "localhost".
func NeedsLocalhostNet(t testing.TB) {
	switch runtime.GOOS {
	case "js", "wasip1":
		t.Skipf(`Listening on "localhost" fails on %s; see https://go.dev/issue/59718`, runtime.GOOS)
	}
}

// Deadline returns the deadline of t, if known,
// using the Deadline method added in Go 1.15.
func Deadline(t testing.TB) (time.Time, bool) {
	td, ok := t.(interface {
		Deadline() (time.Time, bool)
	})
	if !ok {
		return time.Time{}, false
	}
	return td.Deadline()
}

var (
	gorootOnce sync.Once
	gorootPath string
	gorootErr  error
)

func findGOROOT() (string, error) {
	gorootOnce.Do(func() {
		gorootPath = runtime.GOROOT()
		if gorootPath != "" {
			// If runtime.GOROOT() is non-empty, assume that it is valid. (It might
			// not be: for example, the user may have explicitly set GOROOT
			// to the wrong directory.)
			return
		}

		cmd := exec.Command("go", "env", "GOROOT")
		out, err := cmd.Output()
		if err != nil {
			gorootErr = fmt.Errorf("%v: %v", cmd, err)
		}
		gorootPath = strings.TrimSpace(string(out))
	})

	return gorootPath, gorootErr
}

// GOROOT reports the path to the directory containing the root of the Go
// project source tree. This is normally equivalent to runtime.GOROOT, but
// works even if the test binary was built with -trimpath.
//
// If GOROOT cannot be found, GOROOT skips t if t is non-nil,
// or panics otherwise.
func GOROOT(t testing.TB) string {
	path, err := findGOROOT()
	if err != nil {
		if t == nil {
			panic(err)
		}
		t.Helper()
		t.Skip(err)
	}
	return path
}

// NeedsLocalXTools skips t if the golang.org/x/tools module is replaced and
// its replacement directory does not exist (or does not contain the module).
func NeedsLocalXTools(t testing.TB) {
	t.Helper()

	NeedsTool(t, "go")

	cmd := Command(t, "go", "list", "-f", "{{with .Replace}}{{.Dir}}{{end}}", "-m", "golang.org/x/tools")
	out, err := cmd.Output()
	if err != nil {
		if ee, ok := err.(*exec.ExitError); ok && len(ee.Stderr) > 0 {
			t.Skipf("skipping test: %v: %v\n%s", cmd, err, ee.Stderr)
		}
		t.Skipf("skipping test: %v: %v", cmd, err)
	}

	dir := string(bytes.TrimSpace(out))
	if dir == "" {
		// No replacement directory, and (since we didn't set -e) no error either.
		// Maybe x/tools isn't replaced at all (as in a gopls release, or when
		// using a go.work file that includes the x/tools module).
		return
	}

	// We found the directory where x/tools would exist if we're in a clone of the
	// repo. Is it there? (If not, we're probably in the module cache instead.)
	modFilePath := filepath.Join(dir, "go.mod")
	b, err := os.ReadFile(modFilePath)
	if err != nil {
		t.Skipf("skipping test: x/tools replacement not found: %v", err)
	}
	modulePath := modfile.ModulePath(b)

	if want := "golang.org/x/tools"; modulePath != want {
		t.Skipf("skipping test: %s module path is %q, not %q", modFilePath, modulePath, want)
	}
}

// NeedsGoExperiment skips t if the current process environment does not
// have a GOEXPERIMENT flag set.
func NeedsGoExperiment(t testing.TB, flag string) {
	t.Helper()

	goexp := os.Getenv("GOEXPERIMENT")
	set := false
	for f := range strings.SplitSeq(goexp, ",") {
		if f == "" {
			continue
		}
		if f == "none" {
			// GOEXPERIMENT=none disables all experiment flags.
			set = false
			break
		}
		val := true
		if strings.HasPrefix(f, "no") {
			f, val = f[2:], false
		}
		if f == flag {
			set = val
		}
	}
	if !set {
		t.Skipf("skipping test: flag %q is not set in GOEXPERIMENT=%q", flag, goexp)
	}
}

// NeedsGOROOTDir skips the test if GOROOT/dir does not exist, and GOROOT is a
// released version of Go (=has a VERSION file). Some GOROOT directories are
// removed by cmd/distpack.
//
// See also golang/go#70081.
func NeedsGOROOTDir(t *testing.T, dir string) {
	gorootTest := filepath.Join(GOROOT(t), dir)
	if _, err := os.Stat(gorootTest); os.IsNotExist(err) {
		if _, err := os.Stat(filepath.Join(GOROOT(t), "VERSION")); err == nil {
			t.Skipf("skipping: GOROOT/%s not present", dir)
		}
	}
}

// RedirectStderr causes os.Stderr (and the global logger) to be
// temporarily replaced so that writes to it are sent to t.Log.
// It is restored at test cleanup.
func RedirectStderr(t testing.TB) {
	t.Setenv("RedirectStderr", "") // side effect: assert t.Parallel wasn't called

	// TODO(adonovan): if https://go.dev/issue/59928 is accepted,
	// simply set w = t.Output() and dispense with the pipe.
	r, w, err := os.Pipe()
	if err != nil {
		t.Fatalf("pipe: %v", err)
	}
	done := make(chan struct{})
	go func() {
		for sc := bufio.NewScanner(r); sc.Scan(); {
			t.Log(sc.Text())
		}
		r.Close()
		close(done)
	}()

	// Also do the same for the global logger.
	savedWriter, savedPrefix, savedFlags := log.Writer(), log.Prefix(), log.Flags()
	log.SetPrefix("log: ")
	log.SetOutput(w)
	log.SetFlags(0)

	oldStderr := os.Stderr
	os.Stderr = w
	t.Cleanup(func() {
		w.Close() // ignore error
		os.Stderr = oldStderr

		log.SetOutput(savedWriter)
		log.SetPrefix(savedPrefix)
		log.SetFlags(savedFlags)

		// Don't let test finish before final t.Log.
		<-done
	})
}


================================================
FILE: internal/testenv/testenv_notunix.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !(unix || aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris)

package testenv

import "os"

// Sigquit is the signal to send to kill a hanging subprocess.
// On Unix we send SIGQUIT, but on non-Unix we only have os.Kill.
var Sigquit = os.Kill


================================================
FILE: internal/testenv/testenv_unix.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build unix || aix || darwin || dragonfly || freebsd || linux || netbsd || openbsd || solaris

package testenv

import "syscall"

// Sigquit is the signal to send to kill a hanging subprocess.
// Send SIGQUIT to get a stack trace.
var Sigquit = syscall.SIGQUIT


================================================
FILE: internal/testfiles/testdata/somefile.txt
================================================
A file to try to load.

================================================
FILE: internal/testfiles/testdata/versions/go.mod.test
================================================
// File is versions/go.mod after expansion with TestDir()

module golang.org/fake/versions

go 1.22


================================================
FILE: internal/testfiles/testdata/versions/mod.go
================================================
// The file will be go1.22 from the go.mod.

package versions // want "mod.go@go1.22"


================================================
FILE: internal/testfiles/testdata/versions/post.go
================================================
//go:build go1.23

package versions // want "post.go@go1.23"


================================================
FILE: internal/testfiles/testdata/versions/pre.go
================================================
//go:build go1.21

package versions // want "pre.go@go1.21"


================================================
FILE: internal/testfiles/testdata/versions/sub.test/sub.go.test
================================================
package sub // want "sub.go@go1.22"


================================================
FILE: internal/testfiles/testfiles.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package testfiles provides utilities for writing Go tests with files
// in testdata.
package testfiles

import (
	"io/fs"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/txtar"
)

// CopyToTmp copies the files and directories in src to a new temporary testing
// directory dst, and returns dst on success.
//
// After copying the files, it processes each of the 'old,new,' rename
// directives in order. Each rename directive moves the relative path "old"
// to the relative path "new" within the directory.
//
// Renaming allows tests to hide files whose names have
// special meaning, such as "go.mod" files or "testdata" directories
// from the go command, or ill-formed Go source files from gofmt.
//
// For example if we copy the directory testdata:
//
//	testdata/
//	    go.mod.test
//	    a/a.go
//	    b/b.go
//
// with the rename "go.mod.test,go.mod", the resulting files will be:
//
//	dst/
//	    go.mod
//	    a/a.go
//	    b/b.go
func CopyToTmp(t testing.TB, src fs.FS, rename ...string) string {
	dstdir := t.TempDir()

	if err := os.CopyFS(dstdir, src); err != nil {
		t.Fatal(err)
	}
	for _, r := range rename {
		old, new, found := strings.Cut(r, ",")
		if !found {
			t.Fatalf("rename directive %q does not contain delimiter %q", r, ",")
		}
		oldpath := filepath.Join(dstdir, old)
		newpath := filepath.Join(dstdir, new)
		if err := os.Rename(oldpath, newpath); err != nil {
			t.Fatal(err)
		}
	}

	return dstdir
}

// ExtractTxtarFileToTmp read a txtar archive on a given path,
// extracts it to a temporary directory, and returns the
// temporary directory.
func ExtractTxtarFileToTmp(t testing.TB, file string) string {
	ar, err := txtar.ParseFile(file)
	if err != nil {
		t.Fatal(err)
	}

	fs, err := txtar.FS(ar)
	if err != nil {
		t.Fatal(err)
	}
	return CopyToTmp(t, fs)
}

// LoadPackages loads typed syntax for all packages that match the
// patterns, interpreted relative to the archive root.
//
// The packages must be error-free.
func LoadPackages(t testing.TB, ar *txtar.Archive, patterns ...string) []*packages.Package {
	testenv.NeedsGoPackages(t)

	fs, err := txtar.FS(ar)
	if err != nil {
		t.Fatal(err)
	}
	dir := CopyToTmp(t, fs)

	cfg := &packages.Config{
		Mode: packages.NeedSyntax |
			packages.NeedTypesInfo |
			packages.NeedDeps |
			packages.NeedName |
			packages.NeedFiles |
			packages.NeedImports |
			packages.NeedCompiledGoFiles |
			packages.NeedTypes,
		Dir: dir,
		Env: append(os.Environ(),
			"GO111MODULES=on",
			"GOPATH=",
			"GOWORK=off",
			"GOPROXY=off"),
	}
	pkgs, err := packages.Load(cfg, patterns...)
	if err != nil {
		t.Fatal(err)
	}
	if num := packages.PrintErrors(pkgs); num > 0 {
		t.Fatalf("packages contained %d errors", num)
	}
	return pkgs
}


================================================
FILE: internal/testfiles/testfiles_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package testfiles_test

import (
	"fmt"
	"os"
	"path/filepath"
	"testing"

	"golang.org/x/tools/go/analysis"
	"golang.org/x/tools/go/analysis/analysistest"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/internal/versions"
	"golang.org/x/tools/txtar"
)

func TestTestDir(t *testing.T) {
	testenv.NeedsGo1Point(t, 23)

	// Files are initially {go.mod.test,sub.test/sub.go.test}.
	fs := os.DirFS(filepath.Join(analysistest.TestData(), "versions"))
	tmpdir := testfiles.CopyToTmp(t, fs,
		"go.mod.test,go.mod",                // After: {go.mod,sub.test/sub.go.test}
		"sub.test/sub.go.test,sub.test/abc", // After: {go.mod,sub.test/abc}
		"sub.test,sub",                      // After: {go.mod,sub/abc}
		"sub/abc,sub/sub.go",                // After: {go.mod,sub/sub.go}
	)

	filever := &analysis.Analyzer{
		Name: "filever",
		Doc:  "reports file go versions",
		Run: func(pass *analysis.Pass) (any, error) {
			for _, file := range pass.Files {
				ver := versions.FileVersion(pass.TypesInfo, file)
				name := filepath.Base(pass.Fset.Position(file.Package).Filename)
				pass.Reportf(file.Package, "%s@%s", name, ver)
			}
			return nil, nil
		},
	}
	res := analysistest.Run(t, tmpdir, filever, "golang.org/fake/versions", "golang.org/fake/versions/sub")
	got := 0
	for _, r := range res {
		got += len(r.Diagnostics)
	}

	if want := 4; got != want {
		t.Errorf("Got %d diagnostics. wanted %d", got, want)
	}
}

func TestTestDirErrors(t *testing.T) {
	const input = `
-- one.txt --
one
`
	// Files are initially {go.mod.test,sub.test/sub.go.test}.
	fs, err := txtar.FS(txtar.Parse([]byte(input)))
	if err != nil {
		t.Fatal(err)
	}

	directive := "no comma to split on"
	intercept := &fatalIntercept{t, nil}
	func() {
		defer func() { // swallow panics from fatalIntercept.Fatal
			if r := recover(); r != intercept {
				panic(r)
			}
		}()
		testfiles.CopyToTmp(intercept, fs, directive)
	}()

	got := fmt.Sprint(intercept.fatalfs)
	want := `[rename directive "no comma to split on" does not contain delimiter ","]`
	if got != want {
		t.Errorf("CopyToTmp(%q) had the Fatal messages %q. wanted %q", directive, got, want)
	}
}

// helper for TestTestDirErrors
type fatalIntercept struct {
	testing.TB
	fatalfs []string
}

func (i *fatalIntercept) Fatalf(format string, args ...any) {
	i.fatalfs = append(i.fatalfs, fmt.Sprintf(format, args...))
	// Do not mark the test as failing, but fail early.
	panic(i)
}


================================================
FILE: internal/tool/tool.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package tool is a harness for writing Go tools.
package tool

import (
	"context"
	"flag"
	"fmt"
	"log"
	"os"
	"reflect"
	"runtime"
	"runtime/pprof"
	"runtime/trace"
	"strings"
	"time"
)

// This file is a harness for writing your main function.
// The original version of the file is in golang.org/x/tools/internal/tool.
//
// It adds a method to the Application type
//     Main(name, usage string, args []string)
// which should normally be invoked from a true main as follows:
//     func main() {
//       (&Application{}).Main("myapp", "non-flag-command-line-arg-help", os.Args[1:])
//     }
// It recursively scans the application object for fields with a tag containing
//     `flag:"flagnames" help:"short help text"`
// uses all those fields to build command line flags. It will split flagnames on
// commas and add a flag per name.
// It expects the Application type to have a method
//     Run(context.Context, args...string) error
// which it invokes only after all command line flag processing has been finished.
// If Run returns an error, the error will be printed to stderr and the
// application will quit with a non zero exit status.

// Profile can be embedded in your application struct to automatically
// add command line arguments and handling for the common profiling methods.
type Profile struct {
	CPU    string `flag:"profile.cpu" help:"write CPU profile to this file"`
	Memory string `flag:"profile.mem" help:"write memory profile to this file"`
	Alloc  string `flag:"profile.alloc" help:"write alloc profile to this file"`
	Trace  string `flag:"profile.trace" help:"write trace log to this file"`
	Block  string `flag:"profile.block" help:"write block profile to this file"`
}

// Application is the interface that must be satisfied by an object passed to Main.
type Application interface {
	// Name returns the application's name. It is used in help and error messages.
	Name() string
	// Most of the help usage is automatically generated, this string should only
	// describe the contents of non flag arguments.
	Usage() string
	// ShortHelp returns the one line overview of the command.
	ShortHelp() string
	// DetailedHelp should print a detailed help message. It will only ever be shown
	// when the ShortHelp is also printed, so there is no need to duplicate
	// anything from there.
	// It is passed the flag set so it can print the default values of the flags.
	// It should use the flag sets configured Output to write the help to.
	DetailedHelp(*flag.FlagSet)
	// Run is invoked after all flag processing, and inside the profiling and
	// error handling harness.
	Run(ctx context.Context, args ...string) error
}

type SubCommand interface {
	Parent() string
}

// This is the type returned by CommandLineErrorf, which causes the outer main
// to trigger printing of the command line help.
type commandLineError string

func (e commandLineError) Error() string { return string(e) }

// CommandLineErrorf is like fmt.Errorf except that it returns a value that
// triggers printing of the command line help.
// In general you should use this when generating command line validation errors.
func CommandLineErrorf(message string, args ...any) error {
	return commandLineError(fmt.Sprintf(message, args...))
}

// Main should be invoked directly by main function.
// It will only return if there was no error.  If an error
// was encountered it is printed to standard error and the
// application exits with an exit code of 2.
func Main(ctx context.Context, app Application, args []string) {
	s := flag.NewFlagSet(app.Name(), flag.ExitOnError)
	if err := Run(ctx, s, app, args); err != nil {
		fmt.Fprintf(s.Output(), "%s: %v\n", app.Name(), err)
		if _, printHelp := err.(commandLineError); printHelp {
			// TODO(adonovan): refine this. It causes
			// any command-line error to result in the full
			// usage message, which typically obscures
			// the actual error.
			s.Usage()
		}
		os.Exit(2)
	}
}

// Run is the inner loop for Main; invoked by Main, recursively by
// Run, and by various tests.  It runs the application and returns an
// error.
func Run(ctx context.Context, s *flag.FlagSet, app Application, args []string) (resultErr error) {
	s.Usage = func() {
		if app.ShortHelp() != "" {
			fmt.Fprintf(s.Output(), "%s\n\nUsage:\n  ", app.ShortHelp())
			if sub, ok := app.(SubCommand); ok && sub.Parent() != "" {
				fmt.Fprintf(s.Output(), "%s [flags] %s", sub.Parent(), app.Name())
			} else {
				fmt.Fprintf(s.Output(), "%s [flags]", app.Name())
			}
			if usage := app.Usage(); usage != "" {
				fmt.Fprintf(s.Output(), " %s", usage)
			}
			fmt.Fprint(s.Output(), "\n")
		}
		app.DetailedHelp(s)
	}
	p := addFlags(s, reflect.StructField{}, reflect.ValueOf(app))
	if err := s.Parse(args); err != nil {
		return err
	}

	if p != nil && p.CPU != "" {
		f, err := os.Create(p.CPU)
		if err != nil {
			return err
		}
		if err := pprof.StartCPUProfile(f); err != nil {
			f.Close() // ignore error
			return err
		}
		defer func() {
			pprof.StopCPUProfile()
			if closeErr := f.Close(); resultErr == nil {
				resultErr = closeErr
			}
		}()
	}

	if p != nil && p.Trace != "" {
		f, err := os.Create(p.Trace)
		if err != nil {
			return err
		}
		if err := trace.Start(f); err != nil {
			f.Close() // ignore error
			return err
		}
		defer func() {
			trace.Stop()
			if closeErr := f.Close(); resultErr == nil {
				resultErr = closeErr
			}
			log.Printf("To view the trace, run:\n$ go tool trace view %s", p.Trace)
		}()
	}

	if p != nil && p.Memory != "" {
		f, err := os.Create(p.Memory)
		if err != nil {
			return err
		}
		defer func() {
			runtime.GC() // get up-to-date statistics
			if err := pprof.WriteHeapProfile(f); err != nil {
				log.Printf("Writing memory profile: %v", err)
			}
			if err := f.Close(); err != nil {
				log.Printf("Closing memory profile: %v", err)
			}
		}()
	}

	if p != nil && p.Alloc != "" {
		f, err := os.Create(p.Alloc)
		if err != nil {
			return err
		}
		defer func() {
			if err := pprof.Lookup("allocs").WriteTo(f, 0); err != nil {
				log.Printf("Writing alloc profile: %v", err)
			}
			if err := f.Close(); err != nil {
				log.Printf("Closing alloc profile: %v", err)
			}
		}()
	}

	if p != nil && p.Block != "" {
		f, err := os.Create(p.Block)
		if err != nil {
			return err
		}
		runtime.SetBlockProfileRate(1) // record all blocking events
		defer func() {
			if err := pprof.Lookup("block").WriteTo(f, 0); err != nil {
				log.Printf("Writing block profile: %v", err)
			}
			if err := f.Close(); err != nil {
				log.Printf("Closing block profile: %v", err)
			}
		}()
	}

	return app.Run(ctx, s.Args()...)
}

// addFlags scans fields of structs recursively to find things with flag tags
// and add them to the flag set.
func addFlags(f *flag.FlagSet, field reflect.StructField, value reflect.Value) *Profile {
	// is it a field we are allowed to reflect on?
	if field.PkgPath != "" {
		return nil
	}
	// now see if is actually a flag
	flagNames, isFlag := field.Tag.Lookup("flag")
	help := field.Tag.Get("help")
	if isFlag {
		nameList := strings.Split(flagNames, ",")
		// add the main flag
		addFlag(f, value, nameList[0], help)
		if len(nameList) > 1 {
			// and now add any aliases using the same flag value
			fv := f.Lookup(nameList[0]).Value
			for _, flagName := range nameList[1:] {
				f.Var(fv, flagName, help)
			}
		}
		return nil
	}
	// not a flag, but it might be a struct with flags in it
	value = resolve(value.Elem())
	if value.Kind() != reflect.Struct {
		return nil
	}

	// TODO(adonovan): there's no need for this special treatment of Profile:
	// The caller can use f.Lookup("profile.cpu") etc instead.
	p, _ := value.Addr().Interface().(*Profile)
	// go through all the fields of the struct
	for i := 0; i < value.Type().NumField(); i++ {
		child := value.Type().Field(i)
		v := value.Field(i)
		// make sure we have a pointer
		if v.Kind() != reflect.Pointer {
			v = v.Addr()
		}
		// check if that field is a flag or contains flags
		if fp := addFlags(f, child, v); fp != nil {
			p = fp
		}
	}
	return p
}

func addFlag(f *flag.FlagSet, value reflect.Value, flagName string, help string) {
	switch v := value.Interface().(type) {
	case flag.Value:
		f.Var(v, flagName, help)
	case *bool:
		f.BoolVar(v, flagName, *v, help)
	case *time.Duration:
		f.DurationVar(v, flagName, *v, help)
	case *float64:
		f.Float64Var(v, flagName, *v, help)
	case *int64:
		f.Int64Var(v, flagName, *v, help)
	case *int:
		f.IntVar(v, flagName, *v, help)
	case *string:
		f.StringVar(v, flagName, *v, help)
	case *uint:
		f.UintVar(v, flagName, *v, help)
	case *uint64:
		f.Uint64Var(v, flagName, *v, help)
	default:
		log.Fatalf("field %q of type %T is not assignable to flag.Value", flagName, v)
	}
}

func resolve(v reflect.Value) reflect.Value {
	for {
		switch v.Kind() {
		case reflect.Interface, reflect.Pointer:
			v = v.Elem()
		default:
			return v
		}
	}
}


================================================
FILE: internal/typeparams/common.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typeparams contains common utilities for writing tools that
// interact with generic Go code, as introduced with Go 1.18. It
// supplements the standard library APIs. Notably, the StructuralTerms
// API computes a minimal representation of the structural
// restrictions on a type parameter.
//
// An external version of these APIs is available in the
// golang.org/x/exp/typeparams module.
package typeparams

import (
	"go/ast"
	"go/token"
	"go/types"
)

// UnpackIndexExpr extracts data from AST nodes that represent index
// expressions.
//
// For an ast.IndexExpr, the resulting indices slice will contain exactly one
// index expression. For an ast.IndexListExpr (go1.18+), it may have a variable
// number of index expressions.
//
// For nodes that don't represent index expressions, the first return value of
// UnpackIndexExpr will be nil.
func UnpackIndexExpr(n ast.Node) (x ast.Expr, lbrack token.Pos, indices []ast.Expr, rbrack token.Pos) {
	switch e := n.(type) {
	case *ast.IndexExpr:
		return e.X, e.Lbrack, []ast.Expr{e.Index}, e.Rbrack
	case *ast.IndexListExpr:
		return e.X, e.Lbrack, e.Indices, e.Rbrack
	}
	return nil, token.NoPos, nil, token.NoPos
}

// PackIndexExpr returns an *ast.IndexExpr or *ast.IndexListExpr, depending on
// the cardinality of indices. Calling PackIndexExpr with len(indices) == 0
// will panic.
func PackIndexExpr(x ast.Expr, lbrack token.Pos, indices []ast.Expr, rbrack token.Pos) ast.Expr {
	switch len(indices) {
	case 0:
		panic("empty indices")
	case 1:
		return &ast.IndexExpr{
			X:      x,
			Lbrack: lbrack,
			Index:  indices[0],
			Rbrack: rbrack,
		}
	default:
		return &ast.IndexListExpr{
			X:       x,
			Lbrack:  lbrack,
			Indices: indices,
			Rbrack:  rbrack,
		}
	}
}

// IsTypeParam reports whether t is a type parameter (or an alias of one).
func IsTypeParam(t types.Type) bool {
	_, ok := types.Unalias(t).(*types.TypeParam)
	return ok
}


================================================
FILE: internal/typeparams/common_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	. "golang.org/x/tools/internal/typeparams"
)

func TestGetIndexExprData(t *testing.T) {
	x := &ast.Ident{}
	i := &ast.Ident{}

	want := &ast.IndexListExpr{X: x, Lbrack: 1, Indices: []ast.Expr{i}, Rbrack: 2}
	tests := map[ast.Node]bool{
		&ast.IndexExpr{X: x, Lbrack: 1, Index: i, Rbrack: 2}: true,
		want:         true,
		&ast.Ident{}: false,
	}

	for n, isIndexExpr := range tests {
		X, lbrack, indices, rbrack := UnpackIndexExpr(n)
		if got := X != nil; got != isIndexExpr {
			t.Errorf("UnpackIndexExpr(%v) = %v, _, _, _; want nil: %t", n, x, !isIndexExpr)
		}
		if X == nil {
			continue
		}
		if X != x || lbrack != 1 || indices[0] != i || rbrack != 2 {
			t.Errorf("UnpackIndexExprData(%v) = %v, %v, %v, %v; want %+v", n, x, lbrack, indices, rbrack, want)
		}
	}
}

func TestFuncOriginRecursive(t *testing.T) {
	src := `package p

type N[A any] int

func (r N[B]) m() { r.m(); r.n() }

func (r *N[C]) n() { }
`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	info := types.Info{
		Defs: make(map[*ast.Ident]types.Object),
		Uses: make(map[*ast.Ident]types.Object),
	}
	var conf types.Config
	if _, err := conf.Check("p", fset, []*ast.File{f}, &info); err != nil {
		t.Fatal(err)
	}

	// Collect objects from types.Info.
	var m, n *types.Func   // the 'origin' methods in Info.Defs
	var mm, mn *types.Func // the methods used in the body of m

	for _, decl := range f.Decls {
		fdecl, ok := decl.(*ast.FuncDecl)
		if !ok {
			continue
		}
		def := info.Defs[fdecl.Name].(*types.Func)
		switch fdecl.Name.Name {
		case "m":
			m = def
			ast.Inspect(fdecl.Body, func(n ast.Node) bool {
				if call, ok := n.(*ast.CallExpr); ok {
					sel := call.Fun.(*ast.SelectorExpr)
					use := info.Uses[sel.Sel].(*types.Func)
					switch sel.Sel.Name {
					case "m":
						mm = use
					case "n":
						mn = use
					}
				}
				return true
			})
		case "n":
			n = def
		}
	}

	tests := []struct {
		name        string
		input, want *types.Func
	}{
		{"declared m", m, m},
		{"declared n", n, n},
		{"used m", mm, m},
		{"used n", mn, n},
	}

	for _, test := range tests {
		if got := test.input.Origin(); got != test.want {
			t.Errorf("Origin(%q) = %v, want %v", test.name, test.input, test.want)
		}
	}
}

func TestFuncOriginUses(t *testing.T) {

	tests := []string{
		`type T interface { m() }; func _(t T) { t.m() }`,
		`type T[P any] interface { m() P }; func _[A any](t T[A]) { t.m() }`,
		`type T[P any] interface { m() P }; func _(t T[int]) { t.m() }`,
		`type T[P any] int; func (r T[A]) m() { r.m() }`,
		`type T[P any] int; func (r *T[A]) m() { r.m() }`,
		`type T[P any] int; func (r *T[A]) m() {}; func _(t T[int]) { t.m() }`,
		`type T[P any] int; func (r *T[A]) m() {}; func _[A any](t T[A]) { t.m() }`,
	}

	for _, src := range tests {
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "p.go", "package p; "+src, 0)
		if err != nil {
			t.Fatal(err)
		}
		info := types.Info{
			Uses: make(map[*ast.Ident]types.Object),
		}
		var conf types.Config
		pkg, err := conf.Check("p", fset, []*ast.File{f}, &info)
		if err != nil {
			t.Fatal(err)
		}

		// Look up func T.m.
		T := pkg.Scope().Lookup("T").Type()
		obj, _, _ := types.LookupFieldOrMethod(T, true, pkg, "m")
		m := obj.(*types.Func)

		// Assert that the origin of each t.m() call is p.T.m.
		ast.Inspect(f, func(n ast.Node) bool {
			if call, ok := n.(*ast.CallExpr); ok {
				sel := call.Fun.(*ast.SelectorExpr)
				use := info.Uses[sel.Sel].(*types.Func)
				orig := use.Origin()
				if orig != m {
					t.Errorf("%s:\nUses[%v] = %v, want %v", src, types.ExprString(sel), use, m)
				}
			}
			return true
		})
	}
}

// Issue #60628 was a crash in gopls caused by inconsistency (#60634) between
// LookupFieldOrMethod and NewFileSet for methods with an illegal
// *T receiver type, where T itself is a pointer.
// This is a regression test for the workaround in the (now deleted) OriginMethod.
func TestFuncOrigin60628(t *testing.T) {
	const src = `package p; type T[P any] *int; func (r *T[A]) f() {}`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}

	// Expect type error: "invalid receiver type T[A] (pointer or interface type)".
	info := types.Info{
		Uses: make(map[*ast.Ident]types.Object),
	}
	var conf types.Config
	pkg, _ := conf.Check("p", fset, []*ast.File{f}, &info) // error expected
	if pkg == nil {
		t.Fatal("no package")
	}

	// Look up methodset of *T.
	T := pkg.Scope().Lookup("T").Type()
	mset := types.NewMethodSet(types.NewPointer(T))
	if mset.Len() == 0 {
		t.Errorf("NewMethodSet(*T) is empty")
	}
	for sel := range mset.Methods() {
		m := sel.Obj().(*types.Func)

		// TODO(adonovan): check the consistency property required to fix #60634.
		if false {
			m2, _, _ := types.LookupFieldOrMethod(T, true, m.Pkg(), m.Name())
			if m2 != m {
				t.Errorf("LookupFieldOrMethod(%v, indirect=true, %v) = %v, want %v",
					T, m, m2, m)
			}
		}

		// Check the workaround.
		if m.Origin() == nil {
			t.Errorf("Origin(%v) = nil", m)
		}
	}
}


================================================
FILE: internal/typeparams/copytermlist.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build ignore

// copytermlist.go copies the term list algorithm from GOROOT/src/go/types.

package main

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/parser"
	"go/token"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
)

func main() {
	if err := doCopy(); err != nil {
		fmt.Fprintf(os.Stderr, "error copying from go/types: %v", err)
		os.Exit(1)
	}
}

func doCopy() error {
	dir := filepath.Join(runtime.GOROOT(), "src", "go", "types")
	for _, name := range []string{"typeterm.go", "termlist.go"} {
		path := filepath.Join(dir, name)
		fset := token.NewFileSet()
		file, err := parser.ParseFile(fset, path, nil, parser.ParseComments)
		if err != nil {
			return err
		}
		file.Name.Name = "typeparams"
		file.Doc = &ast.CommentGroup{List: []*ast.Comment{{Text: "DO NOT MODIFY"}}}
		var needImport bool
		selectorType := reflect.TypeOf((*ast.SelectorExpr)(nil))
		astutil.Apply(file, func(c *astutil.Cursor) bool {
			if id, _ := c.Node().(*ast.Ident); id != nil {
				// Check if this ident should be qualified with types. For simplicity,
				// assume the copied files do not themselves contain any exported
				// symbols.

				// As a simple heuristic, just verify that the ident may be replaced by
				// a selector.
				if !token.IsExported(id.Name) {
					return false
				}
				v := reflect.TypeOf(c.Parent()).Elem() // ast nodes are all pointers
				field, ok := v.FieldByName(c.Name())
				if !ok {
					panic("missing field")
				}
				t := field.Type
				if c.Index() > 0 { // => t is a slice
					t = t.Elem()
				}
				if !selectorType.AssignableTo(t) {
					return false
				}
				needImport = true
				c.Replace(&ast.SelectorExpr{
					X:   &ast.Ident{NamePos: id.NamePos, Name: "types"},
					Sel: &ast.Ident{NamePos: id.NamePos, Name: id.Name, Obj: id.Obj},
				})
			}
			return true
		}, nil)
		if needImport {
			astutil.AddImport(fset, file, "go/types")
		}

		var b bytes.Buffer
		if err := format.Node(&b, fset, file); err != nil {
			return err
		}

		// Hack in the 'generated' byline.
		content := b.String()
		header := "// Code generated by copytermlist.go DO NOT EDIT.\n\npackage typeparams"
		content = strings.Replace(content, "package typeparams", header, 1)

		if err := os.WriteFile(name, []byte(content), 0644); err != nil {
			return err
		}
	}
	return nil
}


================================================
FILE: internal/typeparams/coretype.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"fmt"
	"go/types"
)

// CoreType returns the core type of T or nil if T does not have a core type.
//
// See https://go.dev/ref/spec#Core_types for the definition of a core type.
func CoreType(T types.Type) types.Type {
	U := T.Underlying()
	if _, ok := U.(*types.Interface); !ok {
		return U // for non-interface types,
	}

	terms, err := NormalTerms(U)
	if len(terms) == 0 || err != nil {
		// len(terms) -> empty type set of interface.
		// err != nil => U is invalid, exceeds complexity bounds, or has an empty type set.
		return nil // no core type.
	}

	U = terms[0].Type().Underlying()
	var identical int // i in [0,identical) => Identical(U, terms[i].Type().Underlying())
	for identical = 1; identical < len(terms); identical++ {
		if !types.Identical(U, terms[identical].Type().Underlying()) {
			break
		}
	}

	if identical == len(terms) {
		// https://go.dev/ref/spec#Core_types
		// "There is a single type U which is the underlying type of all types in the type set of T"
		return U
	}
	ch, ok := U.(*types.Chan)
	if !ok {
		return nil // no core type as identical < len(terms) and U is not a channel.
	}
	// https://go.dev/ref/spec#Core_types
	// "the type chan E if T contains only bidirectional channels, or the type chan<- E or
	// <-chan E depending on the direction of the directional channels present."
	for chans := identical; chans < len(terms); chans++ {
		curr, ok := terms[chans].Type().Underlying().(*types.Chan)
		if !ok {
			return nil
		}
		if !types.Identical(ch.Elem(), curr.Elem()) {
			return nil // channel elements are not identical.
		}
		if ch.Dir() == types.SendRecv {
			// ch is bidirectional. We can safely always use curr's direction.
			ch = curr
		} else if curr.Dir() != types.SendRecv && ch.Dir() != curr.Dir() {
			// ch and curr are not bidirectional and not the same direction.
			return nil
		}
	}
	return ch
}

// NormalTerms returns a slice of terms representing the normalized structural
// type restrictions of a type, if any.
//
// For all types other than *types.TypeParam, *types.Interface, and
// *types.Union, this is just a single term with Tilde() == false and
// Type() == typ. For *types.TypeParam, *types.Interface, and *types.Union, see
// below.
//
// Structural type restrictions of a type parameter are created via
// non-interface types embedded in its constraint interface (directly, or via a
// chain of interface embeddings). For example, in the declaration type
// T[P interface{~int; m()}] int the structural restriction of the type
// parameter P is ~int.
//
// With interface embedding and unions, the specification of structural type
// restrictions may be arbitrarily complex. For example, consider the
// following:
//
//	type A interface{ ~string|~[]byte }
//
//	type B interface{ int|string }
//
//	type C interface { ~string|~int }
//
//	type T[P interface{ A|B; C }] int
//
// In this example, the structural type restriction of P is ~string|int: A|B
// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int,
// which when intersected with C (~string|~int) yields ~string|int.
//
// NormalTerms computes these expansions and reductions, producing a
// "normalized" form of the embeddings. A structural restriction is normalized
// if it is a single union containing no interface terms, and is minimal in the
// sense that removing any term changes the set of types satisfying the
// constraint. It is left as a proof for the reader that, modulo sorting, there
// is exactly one such normalized form.
//
// Because the minimal representation always takes this form, NormalTerms
// returns a slice of tilde terms corresponding to the terms of the union in
// the normalized structural restriction. An error is returned if the type is
// invalid, exceeds complexity bounds, or has an empty type set. In the latter
// case, NormalTerms returns ErrEmptyTypeSet.
//
// NormalTerms makes no guarantees about the order of terms, except that it
// is deterministic.
func NormalTerms(T types.Type) ([]*types.Term, error) {
	// typeSetOf(T) == typeSetOf(Unalias(T))
	typ := types.Unalias(T)
	if named, ok := typ.(*types.Named); ok {
		typ = named.Underlying()
	}
	switch typ := typ.(type) {
	case *types.TypeParam:
		return StructuralTerms(typ)
	case *types.Union:
		return UnionTermSet(typ)
	case *types.Interface:
		return InterfaceTermSet(typ)
	default:
		return []*types.Term{types.NewTerm(false, T)}, nil
	}
}

// Deref returns the type of the variable pointed to by t,
// if t's core type is a pointer; otherwise it returns t.
//
// Do not assume that Deref(T)==T implies T is not a pointer:
// consider "type T *T", for example.
//
// TODO(adonovan): ideally this would live in typesinternal, but that
// creates an import cycle. Move there when we melt this package down.
func Deref(t types.Type) types.Type {
	if ptr, ok := CoreType(t).(*types.Pointer); ok {
		return ptr.Elem()
	}
	return t
}

// MustDeref returns the type of the variable pointed to by t.
// It panics if t's core type is not a pointer.
//
// TODO(adonovan): ideally this would live in typesinternal, but that
// creates an import cycle. Move there when we melt this package down.
func MustDeref(t types.Type) types.Type {
	if ptr, ok := CoreType(t).(*types.Pointer); ok {
		return ptr.Elem()
	}
	panic(fmt.Sprintf("%v is not a pointer", t))
}


================================================
FILE: internal/typeparams/coretype_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/typeparams"
)

func TestCoreType(t *testing.T) {
	const source = `
	package P

	type Named int

	type A any
	type B interface{~int}
	type C interface{int}
	type D interface{Named}
	type E interface{~int|interface{Named}}
	type F interface{~int|~float32}
	type G interface{chan int|interface{chan int}}
	type H interface{chan int|chan float32}
	type I interface{chan<- int|chan int}
	type J interface{chan int|chan<- int}
	type K interface{<-chan int|chan int}
	type L interface{chan int|<-chan int}
	type M interface{chan int|chan Named}
	type N interface{<-chan int|chan<- int}
	type O interface{chan int|bool}
	type P struct{ Named }
	type Q interface{ Foo() }
	type R interface{ Foo() ; Named }
	type S interface{ Foo() ; ~int }

	type T interface{chan int|interface{chan int}|<-chan int}
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		expr string // type expression of Named type
		want string // expected core type (or "<nil>" if none)
	}{
		{"Named", "int"},         // Underlying type is not interface.
		{"A", "<nil>"},           // Interface has no terms.
		{"B", "int"},             // Tilde term.
		{"C", "int"},             // Non-tilde term.
		{"D", "int"},             // Named term.
		{"E", "int"},             // Identical underlying types.
		{"F", "<nil>"},           // Differing underlying types.
		{"G", "chan int"},        // Identical Element types.
		{"H", "<nil>"},           // Element type int has differing underlying type to float32.
		{"I", "chan<- int"},      // SendRecv followed by SendOnly
		{"J", "chan<- int"},      // SendOnly followed by SendRecv
		{"K", "<-chan int"},      // RecvOnly followed by SendRecv
		{"L", "<-chan int"},      // SendRecv followed by RecvOnly
		{"M", "<nil>"},           // Element type int is not *identical* to Named.
		{"N", "<nil>"},           // Differing channel directions
		{"O", "<nil>"},           // A channel followed by a non-channel.
		{"P", "struct{P.Named}"}, // Embedded type.
		{"Q", "<nil>"},           // interface type with no terms and functions
		{"R", "int"},             // interface type with both terms and functions.
		{"S", "int"},             // interface type with a tilde term
		{"T", "<-chan int"},      // Prefix of 2 terms that are identical before switching to channel.
	} {
		// Eval() expr for its type.
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Fatalf("Eval(%s) failed: %v", test.expr, err)
		}

		ct := typeparams.CoreType(tv.Type)
		var got string
		if ct == nil {
			got = "<nil>"
		} else {
			got = ct.String()
		}
		if got != test.want {
			t.Errorf("CoreType(%s) = %v, want %v", test.expr, got, test.want)
		}
	}
}


================================================
FILE: internal/typeparams/free.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"go/types"
)

// Free is a memoization of the set of free type parameters within a
// type. It makes a sequence of calls to [Free.Has] for overlapping
// types more efficient. The zero value is ready for use.
//
// NOTE: Adapted from go/types/infer.go. If it is later exported, factor.
type Free struct {
	seen map[types.Type]bool
}

// Has reports whether the specified type has a free type parameter.
func (w *Free) Has(typ types.Type) (res bool) {
	// detect cycles
	if x, ok := w.seen[typ]; ok {
		return x
	}
	if w.seen == nil {
		w.seen = make(map[types.Type]bool)
	}
	w.seen[typ] = false
	defer func() {
		w.seen[typ] = res
	}()

	switch t := typ.(type) {
	case nil, *types.Basic: // TODO(gri) should nil be handled here?
		break

	case *types.Alias:
		if t.TypeParams().Len() > t.TypeArgs().Len() {
			return true // This is an uninstantiated Alias.
		}
		// The expansion of an alias can have free type parameters,
		// whether or not the alias itself has type parameters:
		//
		//   func _[K comparable]() {
		//     type Set      = map[K]bool // free(Set)      = {K}
		//     type MapTo[V] = map[K]V    // free(Map[foo]) = {V}
		//   }
		//
		// So, we must Unalias.
		return w.Has(types.Unalias(t))

	case *types.Array:
		return w.Has(t.Elem())

	case *types.Slice:
		return w.Has(t.Elem())

	case *types.Struct:
		for i, n := 0, t.NumFields(); i < n; i++ {
			if w.Has(t.Field(i).Type()) {
				return true
			}
		}

	case *types.Pointer:
		return w.Has(t.Elem())

	case *types.Tuple:
		n := t.Len()
		for i := range n {
			if w.Has(t.At(i).Type()) {
				return true
			}
		}

	case *types.Signature:
		// t.tparams may not be nil if we are looking at a signature
		// of a generic function type (or an interface method) that is
		// part of the type we're testing. We don't care about these type
		// parameters.
		// Similarly, the receiver of a method may declare (rather than
		// use) type parameters, we don't care about those either.
		// Thus, we only need to look at the input and result parameters.
		return w.Has(t.Params()) || w.Has(t.Results())

	case *types.Interface:
		for i, n := 0, t.NumMethods(); i < n; i++ {
			if w.Has(t.Method(i).Type()) {
				return true
			}
		}
		terms, err := InterfaceTermSet(t)
		if err != nil {
			return false // ill typed
		}
		for _, term := range terms {
			if w.Has(term.Type()) {
				return true
			}
		}

	case *types.Map:
		return w.Has(t.Key()) || w.Has(t.Elem())

	case *types.Chan:
		return w.Has(t.Elem())

	case *types.Named:
		args := t.TypeArgs()
		if params := t.TypeParams(); params.Len() > args.Len() {
			return true // this is an uninstantiated named type.
		}
		for i, n := 0, args.Len(); i < n; i++ {
			if w.Has(args.At(i)) {
				return true
			}
		}
		return w.Has(t.Underlying()) // recurse for types local to parameterized functions

	case *types.TypeParam:
		return true

	default:
		panic(t) // unreachable
	}

	return false
}


================================================
FILE: internal/typeparams/free_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/testenv"
)

func TestFree(t *testing.T) {
	const source = `
package P
type A int
func (A) f()
func (*A) g()

type fer interface { f() }

func Apply[T fer](x T) T {
	x.f()
	return x
}

type V[T any] []T
func (v *V[T]) Push(x T) { *v = append(*v, x) }
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		expr string // type expression
		want bool   // expected value
	}{
		{"A", false},
		{"*A", false},
		{"error", false},
		{"*error", false},
		{"struct{A}", false},
		{"*struct{A}", false},
		{"fer", false},
		{"Apply", true},
		{"Apply[A]", false},
		{"V", true},
		{"V[A]", false},
		{"*V[A]", false},
		{"(*V[A]).Push", false},
	} {
		tv, err := types.Eval(fset, pkg, 0, test.expr)
		if err != nil {
			t.Errorf("Eval(%s) failed: %v", test.expr, err)
		}

		if got := new(Free).Has(tv.Type); got != test.want {
			t.Logf("Eval(%s) returned the type %s", test.expr, tv.Type)
			t.Errorf("isParameterized(%s) = %v, want %v", test.expr, got, test.want)
		}
	}
}

func TestFree124(t *testing.T) {
	testenv.NeedsGo1Point(t, 24)
	const source = `
package P

func Within[T any]() {
	type p[V []T] = int

	type q[V any] = T

	var end int // end provides a position to test at.
	_ = end
}
`

	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	var conf types.Config
	pkg, err := conf.Check("P", fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err)
	}

	for _, test := range []struct {
		expr string // type expression
		want bool   // expected value
	}{
		{"p", true},       // not an instantiation
		{"p[[]T]", false}, // is an instantiation
		{"q[int]", true},
	} {
		pos := pkg.Scope().Lookup("Within").(*types.Func).Scope().Lookup("end").Pos()
		tv, err := types.Eval(fset, pkg, pos, test.expr)
		if err != nil {
			t.Errorf("Eval(%s) failed: %v", test.expr, err)
		}

		if got := new(Free).Has(tv.Type); got != test.want {
			t.Logf("Eval(%s) returned the type %s", test.expr, tv.Type)
			t.Errorf("isParameterized(%s) = %v, want %v", test.expr, got, test.want)
		}
	}
}


================================================
FILE: internal/typeparams/genericfeatures/features.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// The genericfeatures package provides utilities for detecting usage of
// generic programming in Go packages.
package genericfeatures

import (
	"go/ast"
	"go/types"
	"strings"

	"golang.org/x/tools/go/ast/inspector"
)

// Features is a set of flags reporting which features of generic Go code a
// package uses, or 0.
type Features int

const (
	// GenericTypeDecls indicates whether the package declares types with type
	// parameters.
	GenericTypeDecls Features = 1 << iota

	// GenericFuncDecls indicates whether the package declares functions with
	// type parameters.
	GenericFuncDecls

	// EmbeddedTypeSets indicates whether the package declares interfaces that
	// contain structural type restrictions, i.e. are not fully described by
	// their method sets.
	EmbeddedTypeSets

	// TypeInstantiation indicates whether the package instantiates any generic
	// types.
	TypeInstantiation

	// FuncInstantiation indicates whether the package instantiates any generic
	// functions.
	FuncInstantiation
)

func (f Features) String() string {
	var feats []string
	if f&GenericTypeDecls != 0 {
		feats = append(feats, "typeDecl")
	}
	if f&GenericFuncDecls != 0 {
		feats = append(feats, "funcDecl")
	}
	if f&EmbeddedTypeSets != 0 {
		feats = append(feats, "typeSet")
	}
	if f&TypeInstantiation != 0 {
		feats = append(feats, "typeInstance")
	}
	if f&FuncInstantiation != 0 {
		feats = append(feats, "funcInstance")
	}
	return "features{" + strings.Join(feats, ",") + "}"
}

// ForPackage computes which generic features are used directly by the
// package being analyzed.
func ForPackage(inspect *inspector.Inspector, info *types.Info) Features {
	nodeFilter := []ast.Node{
		(*ast.FuncType)(nil),
		(*ast.InterfaceType)(nil),
		(*ast.ImportSpec)(nil),
		(*ast.TypeSpec)(nil),
	}

	var direct Features

	inspect.Preorder(nodeFilter, func(node ast.Node) {
		switch n := node.(type) {
		case *ast.FuncType:
			if tparams := n.TypeParams; tparams != nil {
				direct |= GenericFuncDecls
			}
		case *ast.InterfaceType:
			tv := info.Types[n] // may be zero
			if iface, _ := tv.Type.(*types.Interface); iface != nil && !iface.IsMethodSet() {
				direct |= EmbeddedTypeSets
			}
		case *ast.TypeSpec:
			if tparams := n.TypeParams; tparams != nil {
				direct |= GenericTypeDecls
			}
		}
	})

	for _, inst := range info.Instances {
		switch types.Unalias(inst.Type).(type) {
		case *types.Named:
			direct |= TypeInstantiation
		case *types.Signature:
			direct |= FuncInstantiation
		}
	}
	return direct
}


================================================
FILE: internal/typeparams/normalize.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams

import (
	"errors"
	"fmt"
	"go/types"
	"os"
	"strings"
)

//go:generate go run copytermlist.go

const debug = false

var ErrEmptyTypeSet = errors.New("empty type set")

// StructuralTerms returns a slice of terms representing the normalized
// structural type restrictions of a type parameter, if any.
//
// Structural type restrictions of a type parameter are created via
// non-interface types embedded in its constraint interface (directly, or via a
// chain of interface embeddings). For example, in the declaration
//
//	type T[P interface{~int; m()}] int
//
// the structural restriction of the type parameter P is ~int.
//
// With interface embedding and unions, the specification of structural type
// restrictions may be arbitrarily complex. For example, consider the
// following:
//
//	type A interface{ ~string|~[]byte }
//
//	type B interface{ int|string }
//
//	type C interface { ~string|~int }
//
//	type T[P interface{ A|B; C }] int
//
// In this example, the structural type restriction of P is ~string|int: A|B
// expands to ~string|~[]byte|int|string, which reduces to ~string|~[]byte|int,
// which when intersected with C (~string|~int) yields ~string|int.
//
// StructuralTerms computes these expansions and reductions, producing a
// "normalized" form of the embeddings. A structural restriction is normalized
// if it is a single union containing no interface terms, and is minimal in the
// sense that removing any term changes the set of types satisfying the
// constraint. It is left as a proof for the reader that, modulo sorting, there
// is exactly one such normalized form.
//
// Because the minimal representation always takes this form, StructuralTerms
// returns a slice of tilde terms corresponding to the terms of the union in
// the normalized structural restriction. An error is returned if the
// constraint interface is invalid, exceeds complexity bounds, or has an empty
// type set. In the latter case, StructuralTerms returns ErrEmptyTypeSet.
//
// StructuralTerms makes no guarantees about the order of terms, except that it
// is deterministic.
func StructuralTerms(tparam *types.TypeParam) ([]*types.Term, error) {
	constraint := tparam.Constraint()
	if constraint == nil {
		return nil, fmt.Errorf("%s has nil constraint", tparam)
	}
	iface, _ := constraint.Underlying().(*types.Interface)
	if iface == nil {
		return nil, fmt.Errorf("constraint is %T, not *types.Interface", constraint.Underlying())
	}
	return InterfaceTermSet(iface)
}

// InterfaceTermSet computes the normalized terms for a constraint interface,
// returning an error if the term set cannot be computed or is empty. In the
// latter case, the error will be ErrEmptyTypeSet.
//
// See the documentation of StructuralTerms for more information on
// normalization.
func InterfaceTermSet(iface *types.Interface) ([]*types.Term, error) {
	return computeTermSet(iface)
}

// UnionTermSet computes the normalized terms for a union, returning an error
// if the term set cannot be computed or is empty. In the latter case, the
// error will be ErrEmptyTypeSet.
//
// See the documentation of StructuralTerms for more information on
// normalization.
func UnionTermSet(union *types.Union) ([]*types.Term, error) {
	return computeTermSet(union)
}

func computeTermSet(typ types.Type) ([]*types.Term, error) {
	tset, err := computeTermSetInternal(typ, make(map[types.Type]*termSet), 0)
	if err != nil {
		return nil, err
	}
	if tset.terms.isEmpty() {
		return nil, ErrEmptyTypeSet
	}
	if tset.terms.isAll() {
		return nil, nil
	}
	var terms []*types.Term
	for _, term := range tset.terms {
		terms = append(terms, types.NewTerm(term.tilde, term.typ))
	}
	return terms, nil
}

// A termSet holds the normalized set of terms for a given type.
//
// The name termSet is intentionally distinct from 'type set': a type set is
// all types that implement a type (and includes method restrictions), whereas
// a term set just represents the structural restrictions on a type.
type termSet struct {
	complete bool
	terms    termlist
}

func indentf(depth int, format string, args ...any) {
	fmt.Fprintf(os.Stderr, strings.Repeat(".", depth)+format+"\n", args...)
}

func computeTermSetInternal(t types.Type, seen map[types.Type]*termSet, depth int) (res *termSet, err error) {
	if t == nil {
		panic("nil type")
	}

	if debug {
		indentf(depth, "%s", t.String())
		defer func() {
			if err != nil {
				indentf(depth, "=> %s", err)
			} else {
				indentf(depth, "=> %s", res.terms.String())
			}
		}()
	}

	const maxTermCount = 100
	if tset, ok := seen[t]; ok {
		if !tset.complete {
			return nil, fmt.Errorf("cycle detected in the declaration of %s", t)
		}
		return tset, nil
	}

	// Mark the current type as seen to avoid infinite recursion.
	tset := new(termSet)
	defer func() {
		tset.complete = true
	}()
	seen[t] = tset

	switch u := t.Underlying().(type) {
	case *types.Interface:
		// The term set of an interface is the intersection of the term sets of its
		// embedded types.
		tset.terms = allTermlist
		for embedded := range u.EmbeddedTypes() {
			if _, ok := embedded.Underlying().(*types.TypeParam); ok {
				return nil, fmt.Errorf("invalid embedded type %T", embedded)
			}
			tset2, err := computeTermSetInternal(embedded, seen, depth+1)
			if err != nil {
				return nil, err
			}
			tset.terms = tset.terms.intersect(tset2.terms)
		}
	case *types.Union:
		// The term set of a union is the union of term sets of its terms.
		tset.terms = nil
		for t := range u.Terms() {
			var terms termlist
			switch t.Type().Underlying().(type) {
			case *types.Interface:
				tset2, err := computeTermSetInternal(t.Type(), seen, depth+1)
				if err != nil {
					return nil, err
				}
				terms = tset2.terms
			case *types.TypeParam, *types.Union:
				// A stand-alone type parameter or union is not permitted as union
				// term.
				return nil, fmt.Errorf("invalid union term %T", t)
			default:
				if t.Type() == types.Typ[types.Invalid] {
					continue
				}
				terms = termlist{{t.Tilde(), t.Type()}}
			}
			tset.terms = tset.terms.union(terms)
			if len(tset.terms) > maxTermCount {
				return nil, fmt.Errorf("exceeded max term count %d", maxTermCount)
			}
		}
	case *types.TypeParam:
		panic("unreachable")
	default:
		// For all other types, the term set is just a single non-tilde term
		// holding the type itself.
		if u != types.Typ[types.Invalid] {
			tset.terms = termlist{{false, t}}
		}
	}
	return tset, nil
}

// under is a facade for the go/types internal function of the same name. It is
// used by typeterm.go.
func under(t types.Type) types.Type {
	return t.Underlying()
}


================================================
FILE: internal/typeparams/normalize_test.go
================================================
// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeparams_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"regexp"
	"strings"
	"testing"

	. "golang.org/x/tools/internal/typeparams"
)

func TestStructuralTerms(t *testing.T) {
	// In the following tests, src must define a type T with (at least) one type
	// parameter. We will compute the structural terms of the first type
	// parameter.
	tests := []struct {
		src       string
		want      string
		wantError string
	}{
		{"package emptyinterface0; type T[P interface{}] int", "all", ""},
		{"package emptyinterface1; type T[P interface{ int | interface{} }] int", "all", ""},
		{"package singleton; type T[P interface{ int }] int", "int", ""},
		{"package under; type T[P interface{~int}] int", "~int", ""},
		{"package superset; type T[P interface{ ~int | int }] int", "~int", ""},
		{"package overlap; type T[P interface{ ~int; int }] int", "int", ""},
		{"package emptyintersection; type T[P interface{ ~int; string }] int", "", "empty type set"},

		{"package embedded0; type T[P interface{ I }] int; type I interface { int }", "int", ""},
		{"package embedded1; type T[P interface{ I | string }] int; type I interface{ int | ~string }", "int ?\\| ?~string", ""},
		{"package embedded2; type T[P interface{ I; string }] int; type I interface{ int | ~string }", "string", ""},

		{"package named; type T[P C] int; type C interface{ ~int|int }", "~int", ""},
		{`// package example is taken from the docstring for StructuralTerms
package example

type A interface{ ~string|~[]byte }

type B interface{ int|string }

type C interface { ~string|~int }

type T[P interface{ A|B; C }] int
`, "~string ?\\| ?int", ""},
	}

	for _, test := range tests {
		fset := token.NewFileSet()
		f, err := parser.ParseFile(fset, "p.go", test.src, 0)
		if err != nil {
			t.Fatal(err)
		}
		t.Run(f.Name.Name, func(t *testing.T) {
			conf := types.Config{
				Error: func(error) {}, // keep going on errors
			}
			pkg, err := conf.Check("", fset, []*ast.File{f}, nil)
			if err != nil {
				t.Logf("types.Config.Check: %v", err)
				// keep going on type checker errors: we want to assert on behavior of
				// invalid code as well.
			}
			obj := pkg.Scope().Lookup("T")
			if obj == nil {
				t.Fatal("type T not found")
			}
			T := obj.Type().(*types.Named).TypeParams().At(0)
			terms, err := StructuralTerms(T)
			if test.wantError != "" {
				if err == nil {
					t.Fatalf("StructuralTerms(%s): nil error, want %q", T, test.wantError)
				}
				if !strings.Contains(err.Error(), test.wantError) {
					t.Errorf("StructuralTerms(%s): err = %q, want %q", T, err, test.wantError)
				}
				return
			}
			if err != nil {
				t.Fatal(err)
			}
			var got string
			if len(terms) == 0 {
				got = "all"
			} else {
				qual := types.RelativeTo(pkg)
				got = types.TypeString(types.NewUnion(terms), qual)
			}
			want := regexp.MustCompile(test.want)
			if !want.MatchString(got) {
				t.Errorf("StructuralTerms(%s) = %q, want %q", T, got, test.want)
			}
		})
	}
}


================================================
FILE: internal/typeparams/termlist.go
================================================
// Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
// Source: ../../cmd/compile/internal/types2/termlist.go

// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copytermlist.go DO NOT EDIT.

package typeparams

import (
	"go/types"
	"strings"
)

// A termlist represents the type set represented by the union
// t1 ∪ y2 ∪ ... tn of the type sets of the terms t1 to tn.
// A termlist is in normal form if all terms are disjoint.
// termlist operations don't require the operands to be in
// normal form.
type termlist []*term

// allTermlist represents the set of all types.
// It is in normal form.
var allTermlist = termlist{new(term)}

// termSep is the separator used between individual terms.
const termSep = " | "

// String prints the termlist exactly (without normalization).
func (xl termlist) String() string {
	if len(xl) == 0 {
		return "∅"
	}
	var buf strings.Builder
	for i, x := range xl {
		if i > 0 {
			buf.WriteString(termSep)
		}
		buf.WriteString(x.String())
	}
	return buf.String()
}

// isEmpty reports whether the termlist xl represents the empty set of types.
func (xl termlist) isEmpty() bool {
	// If there's a non-nil term, the entire list is not empty.
	// If the termlist is in normal form, this requires at most
	// one iteration.
	for _, x := range xl {
		if x != nil {
			return false
		}
	}
	return true
}

// isAll reports whether the termlist xl represents the set of all types.
func (xl termlist) isAll() bool {
	// If there's a 𝓤 term, the entire list is 𝓤.
	// If the termlist is in normal form, this requires at most
	// one iteration.
	for _, x := range xl {
		if x != nil && x.typ == nil {
			return true
		}
	}
	return false
}

// norm returns the normal form of xl.
func (xl termlist) norm() termlist {
	// Quadratic algorithm, but good enough for now.
	// TODO(gri) fix asymptotic performance
	used := make([]bool, len(xl))
	var rl termlist
	for i, xi := range xl {
		if xi == nil || used[i] {
			continue
		}
		for j := i + 1; j < len(xl); j++ {
			xj := xl[j]
			if xj == nil || used[j] {
				continue
			}
			if u1, u2 := xi.union(xj); u2 == nil {
				// If we encounter a 𝓤 term, the entire list is 𝓤.
				// Exit early.
				// (Note that this is not just an optimization;
				// if we continue, we may end up with a 𝓤 term
				// and other terms and the result would not be
				// in normal form.)
				if u1.typ == nil {
					return allTermlist
				}
				xi = u1
				used[j] = true // xj is now unioned into xi - ignore it in future iterations
			}
		}
		rl = append(rl, xi)
	}
	return rl
}

// union returns the union xl ∪ yl.
func (xl termlist) union(yl termlist) termlist {
	return append(xl, yl...).norm()
}

// intersect returns the intersection xl ∩ yl.
func (xl termlist) intersect(yl termlist) termlist {
	if xl.isEmpty() || yl.isEmpty() {
		return nil
	}

	// Quadratic algorithm, but good enough for now.
	// TODO(gri) fix asymptotic performance
	var rl termlist
	for _, x := range xl {
		for _, y := range yl {
			if r := x.intersect(y); r != nil {
				rl = append(rl, r)
			}
		}
	}
	return rl.norm()
}

// equal reports whether xl and yl represent the same type set.
func (xl termlist) equal(yl termlist) bool {
	// TODO(gri) this should be more efficient
	return xl.subsetOf(yl) && yl.subsetOf(xl)
}

// includes reports whether t ∈ xl.
func (xl termlist) includes(t types.Type) bool {
	for _, x := range xl {
		if x.includes(t) {
			return true
		}
	}
	return false
}

// supersetOf reports whether y ⊆ xl.
func (xl termlist) supersetOf(y *term) bool {
	for _, x := range xl {
		if y.subsetOf(x) {
			return true
		}
	}
	return false
}

// subsetOf reports whether xl ⊆ yl.
func (xl termlist) subsetOf(yl termlist) bool {
	if yl.isEmpty() {
		return xl.isEmpty()
	}

	// each term x of xl must be a subset of yl
	for _, x := range xl {
		if !yl.supersetOf(x) {
			return false // x is not a subset yl
		}
	}
	return true
}


================================================
FILE: internal/typeparams/typeterm.go
================================================
// Code generated by "go test -run=Generate -write=all"; DO NOT EDIT.
// Source: ../../cmd/compile/internal/types2/typeterm.go

// Copyright 2021 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Code generated by copytermlist.go DO NOT EDIT.

package typeparams

import "go/types"

// A term describes elementary type sets:
//
//	 ∅:  (*term)(nil)     == ∅                      // set of no types (empty set)
//	 𝓤:  &term{}          == 𝓤                      // set of all types (𝓤niverse)
//	 T:  &term{false, T}  == {T}                    // set of type T
//	~t:  &term{true, t}   == {t' | under(t') == t}  // set of types with underlying type t
type term struct {
	tilde bool // valid if typ != nil
	typ   types.Type
}

func (x *term) String() string {
	switch {
	case x == nil:
		return "∅"
	case x.typ == nil:
		return "𝓤"
	case x.tilde:
		return "~" + x.typ.String()
	default:
		return x.typ.String()
	}
}

// equal reports whether x and y represent the same type set.
func (x *term) equal(y *term) bool {
	// easy cases
	switch {
	case x == nil || y == nil:
		return x == y
	case x.typ == nil || y.typ == nil:
		return x.typ == y.typ
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	return x.tilde == y.tilde && types.Identical(x.typ, y.typ)
}

// union returns the union x ∪ y: zero, one, or two non-nil terms.
func (x *term) union(y *term) (_, _ *term) {
	// easy cases
	switch {
	case x == nil && y == nil:
		return nil, nil // ∅ ∪ ∅ == ∅
	case x == nil:
		return y, nil // ∅ ∪ y == y
	case y == nil:
		return x, nil // x ∪ ∅ == x
	case x.typ == nil:
		return x, nil // 𝓤 ∪ y == 𝓤
	case y.typ == nil:
		return y, nil // x ∪ 𝓤 == 𝓤
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return x, y // x ∪ y == (x, y) if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ∪ ~t == ~t
	// ~t ∪  T == ~t
	//  T ∪ ~t == ~t
	//  T ∪  T ==  T
	if x.tilde || !y.tilde {
		return x, nil
	}
	return y, nil
}

// intersect returns the intersection x ∩ y.
func (x *term) intersect(y *term) *term {
	// easy cases
	switch {
	case x == nil || y == nil:
		return nil // ∅ ∩ y == ∅ and ∩ ∅ == ∅
	case x.typ == nil:
		return y // 𝓤 ∩ y == y
	case y.typ == nil:
		return x // x ∩ 𝓤 == x
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return nil // x ∩ y == ∅ if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ∩ ~t == ~t
	// ~t ∩  T ==  T
	//  T ∩ ~t ==  T
	//  T ∩  T ==  T
	if !x.tilde || y.tilde {
		return x
	}
	return y
}

// includes reports whether t ∈ x.
func (x *term) includes(t types.Type) bool {
	// easy cases
	switch {
	case x == nil:
		return false // t ∈ ∅ == false
	case x.typ == nil:
		return true // t ∈ 𝓤 == true
	}
	// ∅ ⊂ x ⊂ 𝓤

	u := t
	if x.tilde {
		u = under(u)
	}
	return types.Identical(x.typ, u)
}

// subsetOf reports whether x ⊆ y.
func (x *term) subsetOf(y *term) bool {
	// easy cases
	switch {
	case x == nil:
		return true // ∅ ⊆ y == true
	case y == nil:
		return false // x ⊆ ∅ == false since x != ∅
	case y.typ == nil:
		return true // x ⊆ 𝓤 == true
	case x.typ == nil:
		return false // 𝓤 ⊆ y == false since y != 𝓤
	}
	// ∅ ⊂ x, y ⊂ 𝓤

	if x.disjoint(y) {
		return false // x ⊆ y == false if x ∩ y == ∅
	}
	// x.typ == y.typ

	// ~t ⊆ ~t == true
	// ~t ⊆ T == false
	//  T ⊆ ~t == true
	//  T ⊆  T == true
	return !x.tilde || y.tilde
}

// disjoint reports whether x ∩ y == ∅.
// x.typ and y.typ must not be nil.
func (x *term) disjoint(y *term) bool {
	if debug && (x.typ == nil || y.typ == nil) {
		panic("invalid argument(s)")
	}
	ux := x.typ
	if y.tilde {
		ux = under(ux)
	}
	uy := y.typ
	if x.tilde {
		uy = under(uy)
	}
	return !types.Identical(ux, uy)
}


================================================
FILE: internal/typesinternal/classify_call.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"fmt"
	"go/ast"
	"go/types"
	_ "unsafe" // for go:linkname hack
)

// CallKind describes the function position of an [*ast.CallExpr].
type CallKind int

const (
	CallStatic     CallKind = iota // static call to known function
	CallInterface                  // dynamic call through an interface method
	CallDynamic                    // dynamic call of a func value
	CallBuiltin                    // call to a builtin function
	CallConversion                 // a conversion (not a call)
)

var callKindNames = []string{
	"CallStatic",
	"CallInterface",
	"CallDynamic",
	"CallBuiltin",
	"CallConversion",
}

func (k CallKind) String() string {
	if i := int(k); i >= 0 && i < len(callKindNames) {
		return callKindNames[i]
	}
	return fmt.Sprintf("typeutil.CallKind(%d)", k)
}

// ClassifyCall classifies the function position of a call expression ([*ast.CallExpr]).
// It distinguishes among true function calls, calls to builtins, and type conversions,
// and further classifies function calls as static calls (where the function is known),
// dynamic interface calls, and other dynamic calls.
//
// For the declarations:
//
//	func f() {}
//	func g[T any]() {}
//	var v func()
//	var s []func()
//	type I interface { M() }
//	var i I
//
// ClassifyCall returns the following:
//
//	f()           CallStatic
//	g[int]()      CallStatic
//	i.M()         CallInterface
//	min(1, 2)     CallBuiltin
//	v()           CallDynamic
//	s[0]()        CallDynamic
//	int(x)        CallConversion
//	[]byte("")    CallConversion
func ClassifyCall(info *types.Info, call *ast.CallExpr) CallKind {
	if info.Types == nil {
		panic("ClassifyCall: info.Types is nil")
	}
	tv := info.Types[call.Fun]
	if tv.IsType() {
		return CallConversion
	}
	if tv.IsBuiltin() {
		return CallBuiltin
	}
	obj := info.Uses[UsedIdent(info, call.Fun)]
	// Classify the call by the type of the object, if any.
	switch obj := obj.(type) {
	case *types.Func:
		if interfaceMethod(obj) {
			return CallInterface
		}
		return CallStatic
	default:
		return CallDynamic
	}
}

// UsedIdent returns the identifier such that info.Uses[UsedIdent(info, e)]
// is the [types.Object] used by e, if any.
//
// If e is one of various forms of reference:
//
//	f, c, v, T           lexical reference
//	pkg.X                qualified identifier
//	f[T] or pkg.F[K,V]   instantiations of the above kinds
//	expr.f               field or method value selector
//	T.f                  method expression selector
//
// UsedIdent returns the identifier whose is associated value in [types.Info.Uses]
// is the object to which it refers.
//
// For the declarations:
//
//	func F[T any] {...}
//	type I interface { M() }
//	var (
//	  x int
//	  s struct { f  int }
//	  a []int
//	  i I
//	)
//
// UsedIdent returns the following:
//
//	Expr          UsedIdent
//	x             x
//	s.f           f
//	F[int]        F
//	i.M           M
//	I.M           M
//	min           min
//	int           int
//	1             nil
//	a[0]          nil
//	[]byte        nil
//
// Note: if e is an instantiated function or method, UsedIdent returns
// the corresponding generic function or method on the generic type.
func UsedIdent(info *types.Info, e ast.Expr) *ast.Ident {
	return usedIdent(info, e)
}

//go:linkname usedIdent golang.org/x/tools/go/types/typeutil.usedIdent
func usedIdent(info *types.Info, e ast.Expr) *ast.Ident

//go:linkname interfaceMethod golang.org/x/tools/go/types/typeutil.interfaceMethod
func interfaceMethod(f *types.Func) bool


================================================
FILE: internal/typesinternal/classify_call_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal_test

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/format"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	ti "golang.org/x/tools/internal/typesinternal"
)

func TestClassifyCallAndUsed(t *testing.T) {
	const src = `
		package p

		func g(int)

		type A[T any] *T

		func F[T any](T) {}

		type S struct{ f func(int) }
		func (S) g(int)

		type I interface{ m(int) }

		var (
			z S
			a struct{b struct{c S}}
			f = g
			m map[int]func()
			n []func()
			p *int
		)

		func tests[T int]() {
			var zt T

			g(1)
			f(1)
			println()
			z.g(1)       // a concrete method
			a.b.c.g(1)   // same
			S.g(z, 1)    // method expression
			z.f(1)       // struct field
			I(nil).m(1)  // interface method, then type conversion (preorder traversal)
			m[0]()       // a map
			n[0]()       // a slice
			F[int](1)    // instantiated function
			F[T](zt)     // generic function
			func() {}()  // function literal
			_=[]byte("") // type expression
			_=A[int](p)  // instantiated type
			_=T(1)       // type param
			// parenthesized forms
			(z.g)(1)
			(z).g(1)


			// A[T](1)   // generic type: illegal
		}
	`

	fset := token.NewFileSet()
	cfg := &types.Config{
		Error:    func(err error) { t.Fatal(err) },
		Importer: importer.Default(),
	}
	info := ti.NewTypesInfo()
	// parse
	f, err := parser.ParseFile(fset, "classify.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}

	// type-check
	pkg, err := cfg.Check(f.Name.Name, fset, []*ast.File{f}, info)
	if err != nil {
		t.Fatal(err)
	}

	lookup := func(sym string) types.Object {
		return pkg.Scope().Lookup(sym)
	}

	member := func(sym, fieldOrMethod string) types.Object {
		obj, _, _ := types.LookupFieldOrMethod(lookup(sym).Type(), false, pkg, fieldOrMethod)
		return obj
	}

	printlnObj := types.Universe.Lookup("println")

	typeParam := lookup("tests").Type().(*types.Signature).TypeParams().At(0).Obj()

	// Expected Calls are in the order of CallExprs at the end of src, above.
	wants := []struct {
		kind    ti.CallKind
		usedObj types.Object // the object obtained from the result of UsedIdent
	}{
		{ti.CallStatic, lookup("g")},         // g
		{ti.CallDynamic, lookup("f")},        // f
		{ti.CallBuiltin, printlnObj},         // println
		{ti.CallStatic, member("S", "g")},    // z.g
		{ti.CallStatic, member("S", "g")},    // a.b.c.g
		{ti.CallStatic, member("S", "g")},    // S.g(z, 1)
		{ti.CallDynamic, member("z", "f")},   // z.f
		{ti.CallInterface, member("I", "m")}, // I(nil).m
		{ti.CallConversion, lookup("I")},     // I(nil)
		{ti.CallDynamic, nil},                // m[0]
		{ti.CallDynamic, nil},                // n[0]
		{ti.CallStatic, lookup("F")},         // F[int]
		{ti.CallStatic, lookup("F")},         // F[T]
		{ti.CallDynamic, nil},                // f(){}
		{ti.CallConversion, nil},             // []byte
		{ti.CallConversion, lookup("A")},     // A[int]
		{ti.CallConversion, typeParam},       // T
		{ti.CallStatic, member("S", "g")},    // (z.g)
		{ti.CallStatic, member("S", "g")},    // (z).g
	}

	i := 0
	ast.Inspect(f, func(n ast.Node) bool {
		if call, ok := n.(*ast.CallExpr); ok {
			if i >= len(wants) {
				t.Fatal("more calls than wants")
			}
			var buf bytes.Buffer
			if err := format.Node(&buf, fset, n); err != nil {
				t.Fatal(err)
			}
			prefix := fmt.Sprintf("%s (#%d)", buf.String(), i)

			gotKind := ti.ClassifyCall(info, call)
			want := wants[i]

			if gotKind != want.kind {
				t.Errorf("%s kind: got %s, want %s", prefix, gotKind, want.kind)
			}

			w := want.usedObj
			if g := info.Uses[ti.UsedIdent(info, call.Fun)]; g != w {
				t.Errorf("%s used obj: got %v (%[2]T), want %v", prefix, g, w)
			}
			i++
		}
		return true
	})
	if i != len(wants) {
		t.Fatal("more wants than calls")
	}
}


================================================
FILE: internal/typesinternal/element.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"fmt"
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
)

// ForEachElement calls f for type T and each type reachable from its
// type through reflection. It does this by recursively stripping off
// type constructors; in addition, for each named type N, the type *N
// is added to the result as it may have additional methods.
//
// The caller must provide an initially empty set used to de-duplicate
// identical types, potentially across multiple calls to ForEachElement.
// (Its final value holds all the elements seen, matching the arguments
// passed to f.)
//
// TODO(adonovan): share/harmonize with go/callgraph/rta.
func ForEachElement(rtypes *typeutil.Map, msets *typeutil.MethodSetCache, T types.Type, f func(types.Type)) {
	var visit func(T types.Type, skip bool)
	visit = func(T types.Type, skip bool) {
		if !skip {
			if seen, _ := rtypes.Set(T, true).(bool); seen {
				return // de-dup
			}

			f(T) // notify caller of new element type
		}

		// Recursion over signatures of each method.
		tmset := msets.MethodSet(T)
		for method := range tmset.Methods() {
			sig := method.Type().(*types.Signature)
			// It is tempting to call visit(sig, false)
			// but, as noted in golang.org/cl/65450043,
			// the Signature.Recv field is ignored by
			// types.Identical and typeutil.Map, which
			// is confusing at best.
			//
			// More importantly, the true signature rtype
			// reachable from a method using reflection
			// has no receiver but an extra ordinary parameter.
			// For the Read method of io.Reader we want:
			//   func(Reader, []byte) (int, error)
			// but here sig is:
			//   func([]byte) (int, error)
			// with .Recv = Reader (though it is hard to
			// notice because it doesn't affect Signature.String
			// or types.Identical).
			//
			// TODO(adonovan): construct and visit the correct
			// non-method signature with an extra parameter
			// (though since unnamed func types have no methods
			// there is essentially no actual demand for this).
			//
			// TODO(adonovan): document whether or not it is
			// safe to skip non-exported methods (as RTA does).
			visit(sig.Params(), true)  // skip the Tuple
			visit(sig.Results(), true) // skip the Tuple
		}

		switch T := T.(type) {
		case *types.Alias:
			visit(types.Unalias(T), skip) // emulates the pre-Alias behavior

		case *types.Basic:
			// nop

		case *types.Interface:
			// nop---handled by recursion over method set.

		case *types.Pointer:
			visit(T.Elem(), false)

		case *types.Slice:
			visit(T.Elem(), false)

		case *types.Chan:
			visit(T.Elem(), false)

		case *types.Map:
			visit(T.Key(), false)
			visit(T.Elem(), false)

		case *types.Signature:
			if T.Recv() != nil {
				panic(fmt.Sprintf("Signature %s has Recv %s", T, T.Recv()))
			}
			visit(T.Params(), true)  // skip the Tuple
			visit(T.Results(), true) // skip the Tuple

		case *types.Named:
			// A pointer-to-named type can be derived from a named
			// type via reflection.  It may have methods too.
			visit(types.NewPointer(T), false)

			// Consider 'type T struct{S}' where S has methods.
			// Reflection provides no way to get from T to struct{S},
			// only to S, so the method set of struct{S} is unwanted,
			// so set 'skip' flag during recursion.
			visit(T.Underlying(), true) // skip the unnamed type

		case *types.Array:
			visit(T.Elem(), false)

		case *types.Struct:
			for i, n := 0, T.NumFields(); i < n; i++ {
				// TODO(adonovan): document whether or not
				// it is safe to skip non-exported fields.
				visit(T.Field(i).Type(), false)
			}

		case *types.Tuple:
			for i, n := 0, T.Len(); i < n; i++ {
				visit(T.At(i).Type(), false)
			}

		case *types.TypeParam, *types.Union:
			// forEachReachable must not be called on parameterized types.
			panic(T)

		default:
			panic(T)
		}
	}
	visit(T, false)
}


================================================
FILE: internal/typesinternal/element_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"maps"
	"slices"
	"strings"
	"testing"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

const elementSrc = `
package p

type A = int

type B = *map[chan int][]func() [2]bool

type C = T

type T struct{ x int }
func (T) method() uint
func (*T) ptrmethod() complex128

type D = A

type E = struct{ x int }

type F = func(int8, int16) (int32, int64)

type G = struct { U }

type U struct{}
func (U) method() uint32

`

func TestForEachElement(t *testing.T) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "a.go", elementSrc, 0)
	if err != nil {
		t.Fatal(err) // parse error
	}
	var config types.Config
	pkg, err := config.Check(f.Name.Name, fset, []*ast.File{f}, nil)
	if err != nil {
		t.Fatal(err) // type error
	}

	tests := []struct {
		name string   // name of a type alias whose RHS type's elements to compute
		want []string // strings of types that are/are not elements (! => not)
	}{
		// simple type
		{"A", []string{"int"}},

		// compound type
		{"B", []string{
			"*map[chan int][]func() [2]bool",
			"map[chan int][]func() [2]bool",
			"chan int",
			"int",
			"[]func() [2]bool",
			"func() [2]bool",
			"[2]bool",
			"bool",
		}},

		// defined struct type with methods, incl. pointer methods.
		// Observe that it descends into the field type, but
		// the result does not include the struct type itself.
		// (This follows the Go toolchain behavior, and finesses the need
		// to create wrapper methods for that struct type.)
		{"C", []string{"T", "*T", "int", "uint", "complex128", "!struct{x int}"}},

		// alias type
		{"D", []string{"int"}},

		// struct type not beneath a defined type
		{"E", []string{"struct{x int}", "int"}},

		// signature types: the params/results tuples
		// are traversed but not included.
		{"F", []string{"func(int8, int16) (int32, int64)",
			"int8", "int16", "int32", "int64"}},

		// struct with embedded field that has methods
		{"G", []string{"*U", "struct{U}", "uint32", "U"}},
	}
	var msets typeutil.MethodSetCache
	for _, test := range tests {
		tname, ok := pkg.Scope().Lookup(test.name).(*types.TypeName)
		if !ok {
			t.Errorf("no such type %q", test.name)
			continue
		}
		T := types.Unalias(tname.Type())

		toStr := func(T types.Type) string {
			return types.TypeString(T, func(*types.Package) string { return "" })
		}

		got := make(map[string]bool)
		set := new(typeutil.Map)  // for de-duping
		set2 := new(typeutil.Map) // for consistency check
		typesinternal.ForEachElement(set, &msets, T, func(elem types.Type) {
			got[toStr(elem)] = true
			set2.Set(elem, true)
		})

		// Assert that set==set2, meaning f(x) was
		// called for each x in the de-duping map.
		if set.Len() != set2.Len() {
			t.Errorf("ForEachElement called f %d times yet de-dup set has %d elements",
				set2.Len(), set.Len())
		} else {
			set.Iterate(func(key types.Type, _ any) {
				if set2.At(key) == nil {
					t.Errorf("ForEachElement did not call f(%v)", key)
				}
			})
		}

		// Assert than all expected (and no unexpected) elements were found.
		fail := false
		for _, typstr := range test.want {
			found := got[typstr]
			typstr, unwanted := strings.CutPrefix(typstr, "!")
			if found && unwanted {
				fail = true
				t.Errorf("ForEachElement(%s): unwanted element %q", T, typstr)
			} else if !found && !unwanted {
				fail = true
				t.Errorf("ForEachElement(%s): element %q not found", T, typstr)
			}
		}
		if fail {
			t.Logf("got elements:\n%s", strings.Join(slices.Sorted(maps.Keys(got)), "\n"))
		}
	}
}


================================================
FILE: internal/typesinternal/errorcode.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

//go:generate stringer -type=ErrorCode

type ErrorCode int

// This file defines the error codes that can be produced during type-checking.
// Collectively, these codes provide an identifier that may be used to
// implement special handling for certain types of errors.
//
// Error codes should be fine-grained enough that the exact nature of the error
// can be easily determined, but coarse enough that they are not an
// implementation detail of the type checking algorithm. As a rule-of-thumb,
// errors should be considered equivalent if there is a theoretical refactoring
// of the type checker in which they are emitted in exactly one place. For
// example, the type checker emits different error messages for "too many
// arguments" and "too few arguments", but one can imagine an alternative type
// checker where this check instead just emits a single "wrong number of
// arguments", so these errors should have the same code.
//
// Error code names should be as brief as possible while retaining accuracy and
// distinctiveness. In most cases names should start with an adjective
// describing the nature of the error (e.g. "invalid", "unused", "misplaced"),
// and end with a noun identifying the relevant language object. For example,
// "DuplicateDecl" or "InvalidSliceExpr". For brevity, naming follows the
// convention that "bad" implies a problem with syntax, and "invalid" implies a
// problem with types.

const (
	// InvalidSyntaxTree occurs if an invalid syntax tree is provided
	// to the type checker. It should never happen.
	InvalidSyntaxTree ErrorCode = -1
)

const (
	_ ErrorCode = iota

	// Test is reserved for errors that only apply while in self-test mode.
	Test

	/* package names */

	// BlankPkgName occurs when a package name is the blank identifier "_".
	//
	// Per the spec:
	//  "The PackageName must not be the blank identifier."
	BlankPkgName

	// MismatchedPkgName occurs when a file's package name doesn't match the
	// package name already established by other files.
	MismatchedPkgName

	// InvalidPkgUse occurs when a package identifier is used outside of a
	// selector expression.
	//
	// Example:
	//  import "fmt"
	//
	//  var _ = fmt
	InvalidPkgUse

	/* imports */

	// BadImportPath occurs when an import path is not valid.
	BadImportPath

	// BrokenImport occurs when importing a package fails.
	//
	// Example:
	//  import "amissingpackage"
	BrokenImport

	// ImportCRenamed occurs when the special import "C" is renamed. "C" is a
	// pseudo-package, and must not be renamed.
	//
	// Example:
	//  import _ "C"
	ImportCRenamed

	// UnusedImport occurs when an import is unused.
	//
	// Example:
	//  import "fmt"
	//
	//  func main() {}
	UnusedImport

	/* initialization */

	// InvalidInitCycle occurs when an invalid cycle is detected within the
	// initialization graph.
	//
	// Example:
	//  var x int = f()
	//
	//  func f() int { return x }
	InvalidInitCycle

	/* decls */

	// DuplicateDecl occurs when an identifier is declared multiple times.
	//
	// Example:
	//  var x = 1
	//  var x = 2
	DuplicateDecl

	// InvalidDeclCycle occurs when a declaration cycle is not valid.
	//
	// Example:
	//  import "unsafe"
	//
	//  type T struct {
	//  	a [n]int
	//  }
	//
	//  var n = unsafe.Sizeof(T{})
	InvalidDeclCycle

	// InvalidTypeCycle occurs when a cycle in type definitions results in a
	// type that is not well-defined.
	//
	// Example:
	//  import "unsafe"
	//
	//  type T [unsafe.Sizeof(T{})]int
	InvalidTypeCycle

	/* decls > const */

	// InvalidConstInit occurs when a const declaration has a non-constant
	// initializer.
	//
	// Example:
	//  var x int
	//  const _ = x
	InvalidConstInit

	// InvalidConstVal occurs when a const value cannot be converted to its
	// target type.
	//
	// TODO(findleyr): this error code and example are not very clear. Consider
	// removing it.
	//
	// Example:
	//  const _ = 1 << "hello"
	InvalidConstVal

	// InvalidConstType occurs when the underlying type in a const declaration
	// is not a valid constant type.
	//
	// Example:
	//  const c *int = 4
	InvalidConstType

	/* decls > var (+ other variable assignment codes) */

	// UntypedNilUse occurs when the predeclared (untyped) value nil is used to
	// initialize a variable declared without an explicit type.
	//
	// Example:
	//  var x = nil
	UntypedNilUse

	// WrongAssignCount occurs when the number of values on the right-hand side
	// of an assignment or initialization expression does not match the number
	// of variables on the left-hand side.
	//
	// Example:
	//  var x = 1, 2
	WrongAssignCount

	// UnassignableOperand occurs when the left-hand side of an assignment is
	// not assignable.
	//
	// Example:
	//  func f() {
	//  	const c = 1
	//  	c = 2
	//  }
	UnassignableOperand

	// NoNewVar occurs when a short variable declaration (':=') does not declare
	// new variables.
	//
	// Example:
	//  func f() {
	//  	x := 1
	//  	x := 2
	//  }
	NoNewVar

	// MultiValAssignOp occurs when an assignment operation (+=, *=, etc) does
	// not have single-valued left-hand or right-hand side.
	//
	// Per the spec:
	//  "In assignment operations, both the left- and right-hand expression lists
	//  must contain exactly one single-valued expression"
	//
	// Example:
	//  func f() int {
	//  	x, y := 1, 2
	//  	x, y += 1
	//  	return x + y
	//  }
	MultiValAssignOp

	// InvalidIfaceAssign occurs when a value of type T is used as an
	// interface, but T does not implement a method of the expected interface.
	//
	// Example:
	//  type I interface {
	//  	f()
	//  }
	//
	//  type T int
	//
	//  var x I = T(1)
	InvalidIfaceAssign

	// InvalidChanAssign occurs when a chan assignment is invalid.
	//
	// Per the spec, a value x is assignable to a channel type T if:
	//  "x is a bidirectional channel value, T is a channel type, x's type V and
	//  T have identical element types, and at least one of V or T is not a
	//  defined type."
	//
	// Example:
	//  type T1 chan int
	//  type T2 chan int
	//
	//  var x T1
	//  // Invalid assignment because both types are named
	//  var _ T2 = x
	InvalidChanAssign

	// IncompatibleAssign occurs when the type of the right-hand side expression
	// in an assignment cannot be assigned to the type of the variable being
	// assigned.
	//
	// Example:
	//  var x []int
	//  var _ int = x
	IncompatibleAssign

	// UnaddressableFieldAssign occurs when trying to assign to a struct field
	// in a map value.
	//
	// Example:
	//  func f() {
	//  	m := make(map[string]struct{i int})
	//  	m["foo"].i = 42
	//  }
	UnaddressableFieldAssign

	/* decls > type (+ other type expression codes) */

	// NotAType occurs when the identifier used as the underlying type in a type
	// declaration or the right-hand side of a type alias does not denote a type.
	//
	// Example:
	//  var S = 2
	//
	//  type T S
	NotAType

	// InvalidArrayLen occurs when an array length is not a constant value.
	//
	// Example:
	//  var n = 3
	//  var _ = [n]int{}
	InvalidArrayLen

	// BlankIfaceMethod occurs when a method name is '_'.
	//
	// Per the spec:
	//  "The name of each explicitly specified method must be unique and not
	//  blank."
	//
	// Example:
	//  type T interface {
	//  	_(int)
	//  }
	BlankIfaceMethod

	// IncomparableMapKey occurs when a map key type does not support the == and
	// != operators.
	//
	// Per the spec:
	//  "The comparison operators == and != must be fully defined for operands of
	//  the key type; thus the key type must not be a function, map, or slice."
	//
	// Example:
	//  var x map[T]int
	//
	//  type T []int
	IncomparableMapKey

	// InvalidIfaceEmbed occurs when a non-interface type is embedded in an
	// interface.
	//
	// Example:
	//  type T struct {}
	//
	//  func (T) m()
	//
	//  type I interface {
	//  	T
	//  }
	InvalidIfaceEmbed

	// InvalidPtrEmbed occurs when an embedded field is of the pointer form *T,
	// and T itself is itself a pointer, an unsafe.Pointer, or an interface.
	//
	// Per the spec:
	//  "An embedded field must be specified as a type name T or as a pointer to
	//  a non-interface type name *T, and T itself may not be a pointer type."
	//
	// Example:
	//  type T *int
	//
	//  type S struct {
	//  	*T
	//  }
	InvalidPtrEmbed

	/* decls > func and method */

	// BadRecv occurs when a method declaration does not have exactly one
	// receiver parameter.
	//
	// Example:
	//  func () _() {}
	BadRecv

	// InvalidRecv occurs when a receiver type expression is not of the form T
	// or *T, or T is a pointer type.
	//
	// Example:
	//  type T struct {}
	//
	//  func (**T) m() {}
	InvalidRecv

	// DuplicateFieldAndMethod occurs when an identifier appears as both a field
	// and method name.
	//
	// Example:
	//  type T struct {
	//  	m int
	//  }
	//
	//  func (T) m() {}
	DuplicateFieldAndMethod

	// DuplicateMethod occurs when two methods on the same receiver type have
	// the same name.
	//
	// Example:
	//  type T struct {}
	//  func (T) m() {}
	//  func (T) m(i int) int { return i }
	DuplicateMethod

	/* decls > special */

	// InvalidBlank occurs when a blank identifier is used as a value or type.
	//
	// Per the spec:
	//  "The blank identifier may appear as an operand only on the left-hand side
	//  of an assignment."
	//
	// Example:
	//  var x = _
	InvalidBlank

	// InvalidIota occurs when the predeclared identifier iota is used outside
	// of a constant declaration.
	//
	// Example:
	//  var x = iota
	InvalidIota

	// MissingInitBody occurs when an init function is missing its body.
	//
	// Example:
	//  func init()
	MissingInitBody

	// InvalidInitSig occurs when an init function declares parameters or
	// results.
	//
	// Example:
	//  func init() int { return 1 }
	InvalidInitSig

	// InvalidInitDecl occurs when init is declared as anything other than a
	// function.
	//
	// Example:
	//  var init = 1
	InvalidInitDecl

	// InvalidMainDecl occurs when main is declared as anything other than a
	// function, in a main package.
	InvalidMainDecl

	/* exprs */

	// TooManyValues occurs when a function returns too many values for the
	// expression context in which it is used.
	//
	// Example:
	//  func ReturnTwo() (int, int) {
	//  	return 1, 2
	//  }
	//
	//  var x = ReturnTwo()
	TooManyValues

	// NotAnExpr occurs when a type expression is used where a value expression
	// is expected.
	//
	// Example:
	//  type T struct {}
	//
	//  func f() {
	//  	T
	//  }
	NotAnExpr

	/* exprs > const */

	// TruncatedFloat occurs when a float constant is truncated to an integer
	// value.
	//
	// Example:
	//  var _ int = 98.6
	TruncatedFloat

	// NumericOverflow occurs when a numeric constant overflows its target type.
	//
	// Example:
	//  var x int8 = 1000
	NumericOverflow

	/* exprs > operation */

	// UndefinedOp occurs when an operator is not defined for the type(s) used
	// in an operation.
	//
	// Example:
	//  var c = "a" - "b"
	UndefinedOp

	// MismatchedTypes occurs when operand types are incompatible in a binary
	// operation.
	//
	// Example:
	//  var a = "hello"
	//  var b = 1
	//  var c = a - b
	MismatchedTypes

	// DivByZero occurs when a division operation is provable at compile
	// time to be a division by zero.
	//
	// Example:
	//  const divisor = 0
	//  var x int = 1/divisor
	DivByZero

	// NonNumericIncDec occurs when an increment or decrement operator is
	// applied to a non-numeric value.
	//
	// Example:
	//  func f() {
	//  	var c = "c"
	//  	c++
	//  }
	NonNumericIncDec

	/* exprs > ptr */

	// UnaddressableOperand occurs when the & operator is applied to an
	// unaddressable expression.
	//
	// Example:
	//  var x = &1
	UnaddressableOperand

	// InvalidIndirection occurs when a non-pointer value is indirected via the
	// '*' operator.
	//
	// Example:
	//  var x int
	//  var y = *x
	InvalidIndirection

	/* exprs > [] */

	// NonIndexableOperand occurs when an index operation is applied to a value
	// that cannot be indexed.
	//
	// Example:
	//  var x = 1
	//  var y = x[1]
	NonIndexableOperand

	// InvalidIndex occurs when an index argument is not of integer type,
	// negative, or out-of-bounds.
	//
	// Example:
	//  var s = [...]int{1,2,3}
	//  var x = s[5]
	//
	// Example:
	//  var s = []int{1,2,3}
	//  var _ = s[-1]
	//
	// Example:
	//  var s = []int{1,2,3}
	//  var i string
	//  var _ = s[i]
	InvalidIndex

	// SwappedSliceIndices occurs when constant indices in a slice expression
	// are decreasing in value.
	//
	// Example:
	//  var _ = []int{1,2,3}[2:1]
	SwappedSliceIndices

	/* operators > slice */

	// NonSliceableOperand occurs when a slice operation is applied to a value
	// whose type is not sliceable, or is unaddressable.
	//
	// Example:
	//  var x = [...]int{1, 2, 3}[:1]
	//
	// Example:
	//  var x = 1
	//  var y = 1[:1]
	NonSliceableOperand

	// InvalidSliceExpr occurs when a three-index slice expression (a[x:y:z]) is
	// applied to a string.
	//
	// Example:
	//  var s = "hello"
	//  var x = s[1:2:3]
	InvalidSliceExpr

	/* exprs > shift */

	// InvalidShiftCount occurs when the right-hand side of a shift operation is
	// either non-integer, negative, or too large.
	//
	// Example:
	//  var (
	//  	x string
	//  	y int = 1 << x
	//  )
	InvalidShiftCount

	// InvalidShiftOperand occurs when the shifted operand is not an integer.
	//
	// Example:
	//  var s = "hello"
	//  var x = s << 2
	InvalidShiftOperand

	/* exprs > chan */

	// InvalidReceive occurs when there is a channel receive from a value that
	// is either not a channel, or is a send-only channel.
	//
	// Example:
	//  func f() {
	//  	var x = 1
	//  	<-x
	//  }
	InvalidReceive

	// InvalidSend occurs when there is a channel send to a value that is not a
	// channel, or is a receive-only channel.
	//
	// Example:
	//  func f() {
	//  	var x = 1
	//  	x <- "hello!"
	//  }
	InvalidSend

	/* exprs > literal */

	// DuplicateLitKey occurs when an index is duplicated in a slice, array, or
	// map literal.
	//
	// Example:
	//  var _ = []int{0:1, 0:2}
	//
	// Example:
	//  var _ = map[string]int{"a": 1, "a": 2}
	DuplicateLitKey

	// MissingLitKey occurs when a map literal is missing a key expression.
	//
	// Example:
	//  var _ = map[string]int{1}
	MissingLitKey

	// InvalidLitIndex occurs when the key in a key-value element of a slice or
	// array literal is not an integer constant.
	//
	// Example:
	//  var i = 0
	//  var x = []string{i: "world"}
	InvalidLitIndex

	// OversizeArrayLit occurs when an array literal exceeds its length.
	//
	// Example:
	//  var _ = [2]int{1,2,3}
	OversizeArrayLit

	// MixedStructLit occurs when a struct literal contains a mix of positional
	// and named elements.
	//
	// Example:
	//  var _ = struct{i, j int}{i: 1, 2}
	MixedStructLit

	// InvalidStructLit occurs when a positional struct literal has an incorrect
	// number of values.
	//
	// Example:
	//  var _ = struct{i, j int}{1,2,3}
	InvalidStructLit

	// MissingLitField occurs when a struct literal refers to a field that does
	// not exist on the struct type.
	//
	// Example:
	//  var _ = struct{i int}{j: 2}
	MissingLitField

	// DuplicateLitField occurs when a struct literal contains duplicated
	// fields.
	//
	// Example:
	//  var _ = struct{i int}{i: 1, i: 2}
	DuplicateLitField

	// UnexportedLitField occurs when a positional struct literal implicitly
	// assigns an unexported field of an imported type.
	UnexportedLitField

	// InvalidLitField occurs when a field name is not a valid identifier.
	//
	// Example:
	//  var _ = struct{i int}{1: 1}
	InvalidLitField

	// UntypedLit occurs when a composite literal omits a required type
	// identifier.
	//
	// Example:
	//  type outer struct{
	//  	inner struct { i int }
	//  }
	//
	//  var _ = outer{inner: {1}}
	UntypedLit

	// InvalidLit occurs when a composite literal expression does not match its
	// type.
	//
	// Example:
	//  type P *struct{
	//  	x int
	//  }
	//  var _ = P {}
	InvalidLit

	/* exprs > selector */

	// AmbiguousSelector occurs when a selector is ambiguous.
	//
	// Example:
	//  type E1 struct { i int }
	//  type E2 struct { i int }
	//  type T struct { E1; E2 }
	//
	//  var x T
	//  var _ = x.i
	AmbiguousSelector

	// UndeclaredImportedName occurs when a package-qualified identifier is
	// undeclared by the imported package.
	//
	// Example:
	//  import "go/types"
	//
	//  var _ = types.NotAnActualIdentifier
	UndeclaredImportedName

	// UnexportedName occurs when a selector refers to an unexported identifier
	// of an imported package.
	//
	// Example:
	//  import "reflect"
	//
	//  type _ reflect.flag
	UnexportedName

	// UndeclaredName occurs when an identifier is not declared in the current
	// scope.
	//
	// Example:
	//  var x T
	UndeclaredName

	// MissingFieldOrMethod occurs when a selector references a field or method
	// that does not exist.
	//
	// Example:
	//  type T struct {}
	//
	//  var x = T{}.f
	MissingFieldOrMethod

	/* exprs > ... */

	// BadDotDotDotSyntax occurs when a "..." occurs in a context where it is
	// not valid.
	//
	// Example:
	//  var _ = map[int][...]int{0: {}}
	BadDotDotDotSyntax

	// NonVariadicDotDotDot occurs when a "..." is used on the final argument to
	// a non-variadic function.
	//
	// Example:
	//  func printArgs(s []string) {
	//  	for _, a := range s {
	//  		println(a)
	//  	}
	//  }
	//
	//  func f() {
	//  	s := []string{"a", "b", "c"}
	//  	printArgs(s...)
	//  }
	NonVariadicDotDotDot

	// MisplacedDotDotDot occurs when a "..." is used somewhere other than the
	// final argument to a function call.
	//
	// Example:
	//  func printArgs(args ...int) {
	//  	for _, a := range args {
	//  		println(a)
	//  	}
	//  }
	//
	//  func f() {
	//  	a := []int{1,2,3}
	//  	printArgs(0, a...)
	//  }
	MisplacedDotDotDot

	// InvalidDotDotDotOperand occurs when a "..." operator is applied to a
	// single-valued operand.
	//
	// Example:
	//  func printArgs(args ...int) {
	//  	for _, a := range args {
	//  		println(a)
	//  	}
	//  }
	//
	//  func f() {
	//  	a := 1
	//  	printArgs(a...)
	//  }
	//
	// Example:
	//  func args() (int, int) {
	//  	return 1, 2
	//  }
	//
	//  func printArgs(args ...int) {
	//  	for _, a := range args {
	//  		println(a)
	//  	}
	//  }
	//
	//  func g() {
	//  	printArgs(args()...)
	//  }
	InvalidDotDotDotOperand

	// InvalidDotDotDot occurs when a "..." is used in a non-variadic built-in
	// function.
	//
	// Example:
	//  var s = []int{1, 2, 3}
	//  var l = len(s...)
	InvalidDotDotDot

	/* exprs > built-in */

	// UncalledBuiltin occurs when a built-in function is used as a
	// function-valued expression, instead of being called.
	//
	// Per the spec:
	//  "The built-in functions do not have standard Go types, so they can only
	//  appear in call expressions; they cannot be used as function values."
	//
	// Example:
	//  var _ = copy
	UncalledBuiltin

	// InvalidAppend occurs when append is called with a first argument that is
	// not a slice.
	//
	// Example:
	//  var _ = append(1, 2)
	InvalidAppend

	// InvalidCap occurs when an argument to the cap built-in function is not of
	// supported type.
	//
	// See https://golang.org/ref/spec#Length_and_capacity for information on
	// which underlying types are supported as arguments to cap and len.
	//
	// Example:
	//  var s = 2
	//  var x = cap(s)
	InvalidCap

	// InvalidClose occurs when close(...) is called with an argument that is
	// not of channel type, or that is a receive-only channel.
	//
	// Example:
	//  func f() {
	//  	var x int
	//  	close(x)
	//  }
	InvalidClose

	// InvalidCopy occurs when the arguments are not of slice type or do not
	// have compatible type.
	//
	// See https://golang.org/ref/spec#Appending_and_copying_slices for more
	// information on the type requirements for the copy built-in.
	//
	// Example:
	//  func f() {
	//  	var x []int
	//  	y := []int64{1,2,3}
	//  	copy(x, y)
	//  }
	InvalidCopy

	// InvalidComplex occurs when the complex built-in function is called with
	// arguments with incompatible types.
	//
	// Example:
	//  var _ = complex(float32(1), float64(2))
	InvalidComplex

	// InvalidDelete occurs when the delete built-in function is called with a
	// first argument that is not a map.
	//
	// Example:
	//  func f() {
	//  	m := "hello"
	//  	delete(m, "e")
	//  }
	InvalidDelete

	// InvalidImag occurs when the imag built-in function is called with an
	// argument that does not have complex type.
	//
	// Example:
	//  var _ = imag(int(1))
	InvalidImag

	// InvalidLen occurs when an argument to the len built-in function is not of
	// supported type.
	//
	// See https://golang.org/ref/spec#Length_and_capacity for information on
	// which underlying types are supported as arguments to cap and len.
	//
	// Example:
	//  var s = 2
	//  var x = len(s)
	InvalidLen

	// SwappedMakeArgs occurs when make is called with three arguments, and its
	// length argument is larger than its capacity argument.
	//
	// Example:
	//  var x = make([]int, 3, 2)
	SwappedMakeArgs

	// InvalidMake occurs when make is called with an unsupported type argument.
	//
	// See https://golang.org/ref/spec#Making_slices_maps_and_channels for
	// information on the types that may be created using make.
	//
	// Example:
	//  var x = make(int)
	InvalidMake

	// InvalidReal occurs when the real built-in function is called with an
	// argument that does not have complex type.
	//
	// Example:
	//  var _ = real(int(1))
	InvalidReal

	/* exprs > assertion */

	// InvalidAssert occurs when a type assertion is applied to a
	// value that is not of interface type.
	//
	// Example:
	//  var x = 1
	//  var _ = x.(float64)
	InvalidAssert

	// ImpossibleAssert occurs for a type assertion x.(T) when the value x of
	// interface cannot have dynamic type T, due to a missing or mismatching
	// method on T.
	//
	// Example:
	//  type T int
	//
	//  func (t *T) m() int { return int(*t) }
	//
	//  type I interface { m() int }
	//
	//  var x I
	//  var _ = x.(T)
	ImpossibleAssert

	/* exprs > conversion */

	// InvalidConversion occurs when the argument type cannot be converted to the
	// target.
	//
	// See https://golang.org/ref/spec#Conversions for the rules of
	// convertibility.
	//
	// Example:
	//  var x float64
	//  var _ = string(x)
	InvalidConversion

	// InvalidUntypedConversion occurs when there is no valid implicit
	// conversion from an untyped value satisfying the type constraints of the
	// context in which it is used.
	//
	// Example:
	//  var _ = 1 + ""
	InvalidUntypedConversion

	/* offsetof */

	// BadOffsetofSyntax occurs when unsafe.Offsetof is called with an argument
	// that is not a selector expression.
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.Offsetof(x)
	BadOffsetofSyntax

	// InvalidOffsetof occurs when unsafe.Offsetof is called with a method
	// selector, rather than a field selector, or when the field is embedded via
	// a pointer.
	//
	// Per the spec:
	//
	//  "If f is an embedded field, it must be reachable without pointer
	//  indirections through fields of the struct. "
	//
	// Example:
	//  import "unsafe"
	//
	//  type T struct { f int }
	//  type S struct { *T }
	//  var s S
	//  var _ = unsafe.Offsetof(s.f)
	//
	// Example:
	//  import "unsafe"
	//
	//  type S struct{}
	//
	//  func (S) m() {}
	//
	//  var s S
	//  var _ = unsafe.Offsetof(s.m)
	InvalidOffsetof

	/* control flow > scope */

	// UnusedExpr occurs when a side-effect free expression is used as a
	// statement. Such a statement has no effect.
	//
	// Example:
	//  func f(i int) {
	//  	i*i
	//  }
	UnusedExpr

	// UnusedVar occurs when a variable is declared but unused.
	//
	// Example:
	//  func f() {
	//  	x := 1
	//  }
	UnusedVar

	// MissingReturn occurs when a function with results is missing a return
	// statement.
	//
	// Example:
	//  func f() int {}
	MissingReturn

	// WrongResultCount occurs when a return statement returns an incorrect
	// number of values.
	//
	// Example:
	//  func ReturnOne() int {
	//  	return 1, 2
	//  }
	WrongResultCount

	// OutOfScopeResult occurs when the name of a value implicitly returned by
	// an empty return statement is shadowed in a nested scope.
	//
	// Example:
	//  func factor(n int) (i int) {
	//  	for i := 2; i < n; i++ {
	//  		if n%i == 0 {
	//  			return
	//  		}
	//  	}
	//  	return 0
	//  }
	OutOfScopeResult

	/* control flow > if */

	// InvalidCond occurs when an if condition is not a boolean expression.
	//
	// Example:
	//  func checkReturn(i int) {
	//  	if i {
	//  		panic("non-zero return")
	//  	}
	//  }
	InvalidCond

	/* control flow > for */

	// InvalidPostDecl occurs when there is a declaration in a for-loop post
	// statement.
	//
	// Example:
	//  func f() {
	//  	for i := 0; i < 10; j := 0 {}
	//  }
	InvalidPostDecl

	// InvalidChanRange occurs when a send-only channel used in a range
	// expression.
	//
	// Example:
	//  func sum(c chan<- int) {
	//  	s := 0
	//  	for i := range c {
	//  		s += i
	//  	}
	//  }
	InvalidChanRange

	// InvalidIterVar occurs when two iteration variables are used while ranging
	// over a channel.
	//
	// Example:
	//  func f(c chan int) {
	//  	for k, v := range c {
	//  		println(k, v)
	//  	}
	//  }
	InvalidIterVar

	// InvalidRangeExpr occurs when the type of a range expression is not array,
	// slice, string, map, or channel.
	//
	// Example:
	//  func f(i int) {
	//  	for j := range i {
	//  		println(j)
	//  	}
	//  }
	InvalidRangeExpr

	/* control flow > switch */

	// MisplacedBreak occurs when a break statement is not within a for, switch,
	// or select statement of the innermost function definition.
	//
	// Example:
	//  func f() {
	//  	break
	//  }
	MisplacedBreak

	// MisplacedContinue occurs when a continue statement is not within a for
	// loop of the innermost function definition.
	//
	// Example:
	//  func sumeven(n int) int {
	//  	proceed := func() {
	//  		continue
	//  	}
	//  	sum := 0
	//  	for i := 1; i <= n; i++ {
	//  		if i % 2 != 0 {
	//  			proceed()
	//  		}
	//  		sum += i
	//  	}
	//  	return sum
	//  }
	MisplacedContinue

	// MisplacedFallthrough occurs when a fallthrough statement is not within an
	// expression switch.
	//
	// Example:
	//  func typename(i interface{}) string {
	//  	switch i.(type) {
	//  	case int64:
	//  		fallthrough
	//  	case int:
	//  		return "int"
	//  	}
	//  	return "unsupported"
	//  }
	MisplacedFallthrough

	// DuplicateCase occurs when a type or expression switch has duplicate
	// cases.
	//
	// Example:
	//  func printInt(i int) {
	//  	switch i {
	//  	case 1:
	//  		println("one")
	//  	case 1:
	//  		println("One")
	//  	}
	//  }
	DuplicateCase

	// DuplicateDefault occurs when a type or expression switch has multiple
	// default clauses.
	//
	// Example:
	//  func printInt(i int) {
	//  	switch i {
	//  	case 1:
	//  		println("one")
	//  	default:
	//  		println("One")
	//  	default:
	//  		println("1")
	//  	}
	//  }
	DuplicateDefault

	// BadTypeKeyword occurs when a .(type) expression is used anywhere other
	// than a type switch.
	//
	// Example:
	//  type I interface {
	//  	m()
	//  }
	//  var t I
	//  var _ = t.(type)
	BadTypeKeyword

	// InvalidTypeSwitch occurs when .(type) is used on an expression that is
	// not of interface type.
	//
	// Example:
	//  func f(i int) {
	//  	switch x := i.(type) {}
	//  }
	InvalidTypeSwitch

	// InvalidExprSwitch occurs when a switch expression is not comparable.
	//
	// Example:
	//  func _() {
	//  	var a struct{ _ func() }
	//  	switch a /* ERROR cannot switch on a */ {
	//  	}
	//  }
	InvalidExprSwitch

	/* control flow > select */

	// InvalidSelectCase occurs when a select case is not a channel send or
	// receive.
	//
	// Example:
	//  func checkChan(c <-chan int) bool {
	//  	select {
	//  	case c:
	//  		return true
	//  	default:
	//  		return false
	//  	}
	//  }
	InvalidSelectCase

	/* control flow > labels and jumps */

	// UndeclaredLabel occurs when an undeclared label is jumped to.
	//
	// Example:
	//  func f() {
	//  	goto L
	//  }
	UndeclaredLabel

	// DuplicateLabel occurs when a label is declared more than once.
	//
	// Example:
	//  func f() int {
	//  L:
	//  L:
	//  	return 1
	//  }
	DuplicateLabel

	// MisplacedLabel occurs when a break or continue label is not on a for,
	// switch, or select statement.
	//
	// Example:
	//  func f() {
	//  L:
	//  	a := []int{1,2,3}
	//  	for _, e := range a {
	//  		if e > 10 {
	//  			break L
	//  		}
	//  		println(a)
	//  	}
	//  }
	MisplacedLabel

	// UnusedLabel occurs when a label is declared but not used.
	//
	// Example:
	//  func f() {
	//  L:
	//  }
	UnusedLabel

	// JumpOverDecl occurs when a label jumps over a variable declaration.
	//
	// Example:
	//  func f() int {
	//  	goto L
	//  	x := 2
	//  L:
	//  	x++
	//  	return x
	//  }
	JumpOverDecl

	// JumpIntoBlock occurs when a forward jump goes to a label inside a nested
	// block.
	//
	// Example:
	//  func f(x int) {
	//  	goto L
	//  	if x > 0 {
	//  	L:
	//  		print("inside block")
	//  	}
	// }
	JumpIntoBlock

	/* control flow > calls */

	// InvalidMethodExpr occurs when a pointer method is called but the argument
	// is not addressable.
	//
	// Example:
	//  type T struct {}
	//
	//  func (*T) m() int { return 1 }
	//
	//  var _ = T.m(T{})
	InvalidMethodExpr

	// WrongArgCount occurs when too few or too many arguments are passed by a
	// function call.
	//
	// Example:
	//  func f(i int) {}
	//  var x = f()
	WrongArgCount

	// InvalidCall occurs when an expression is called that is not of function
	// type.
	//
	// Example:
	//  var x = "x"
	//  var y = x()
	InvalidCall

	/* control flow > suspended */

	// UnusedResults occurs when a restricted expression-only built-in function
	// is suspended via go or defer. Such a suspension discards the results of
	// these side-effect free built-in functions, and therefore is ineffectual.
	//
	// Example:
	//  func f(a []int) int {
	//  	defer len(a)
	//  	return i
	//  }
	UnusedResults

	// InvalidDefer occurs when a deferred expression is not a function call,
	// for example if the expression is a type conversion.
	//
	// Example:
	//  func f(i int) int {
	//  	defer int32(i)
	//  	return i
	//  }
	InvalidDefer

	// InvalidGo occurs when a go expression is not a function call, for example
	// if the expression is a type conversion.
	//
	// Example:
	//  func f(i int) int {
	//  	go int32(i)
	//  	return i
	//  }
	InvalidGo

	// All codes below were added in Go 1.17.

	/* decl */

	// BadDecl occurs when a declaration has invalid syntax.
	BadDecl

	// RepeatedDecl occurs when an identifier occurs more than once on the left
	// hand side of a short variable declaration.
	//
	// Example:
	//  func _() {
	//  	x, y, y := 1, 2, 3
	//  }
	RepeatedDecl

	/* unsafe */

	// InvalidUnsafeAdd occurs when unsafe.Add is called with a
	// length argument that is not of integer type.
	//
	// Example:
	//  import "unsafe"
	//
	//  var p unsafe.Pointer
	//  var _ = unsafe.Add(p, float64(1))
	InvalidUnsafeAdd

	// InvalidUnsafeSlice occurs when unsafe.Slice is called with a
	// pointer argument that is not of pointer type or a length argument
	// that is not of integer type, negative, or out of bounds.
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.Slice(x, 1)
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.Slice(&x, float64(1))
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.Slice(&x, -1)
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.Slice(&x, uint64(1) << 63)
	InvalidUnsafeSlice

	// All codes below were added in Go 1.18.

	/* features */

	// UnsupportedFeature occurs when a language feature is used that is not
	// supported at this Go version.
	UnsupportedFeature

	/* type params */

	// NotAGenericType occurs when a non-generic type is used where a generic
	// type is expected: in type or function instantiation.
	//
	// Example:
	//  type T int
	//
	//  var _ T[int]
	NotAGenericType

	// WrongTypeArgCount occurs when a type or function is instantiated with an
	// incorrect number of type arguments, including when a generic type or
	// function is used without instantiation.
	//
	// Errors involving failed type inference are assigned other error codes.
	//
	// Example:
	//  type T[p any] int
	//
	//  var _ T[int, string]
	//
	// Example:
	//  func f[T any]() {}
	//
	//  var x = f
	WrongTypeArgCount

	// CannotInferTypeArgs occurs when type or function type argument inference
	// fails to infer all type arguments.
	//
	// Example:
	//  func f[T any]() {}
	//
	//  func _() {
	//  	f()
	//  }
	//
	// Example:
	//   type N[P, Q any] struct{}
	//
	//   var _ N[int]
	CannotInferTypeArgs

	// InvalidTypeArg occurs when a type argument does not satisfy its
	// corresponding type parameter constraints.
	//
	// Example:
	//  type T[P ~int] struct{}
	//
	//  var _ T[string]
	InvalidTypeArg // arguments? InferenceFailed

	// InvalidInstanceCycle occurs when an invalid cycle is detected
	// within the instantiation graph.
	//
	// Example:
	//  func f[T any]() { f[*T]() }
	InvalidInstanceCycle

	// InvalidUnion occurs when an embedded union or approximation element is
	// not valid.
	//
	// Example:
	//  type _ interface {
	//   	~int | interface{ m() }
	//  }
	InvalidUnion

	// MisplacedConstraintIface occurs when a constraint-type interface is used
	// outside of constraint position.
	//
	// Example:
	//   type I interface { ~int }
	//
	//   var _ I
	MisplacedConstraintIface

	// InvalidMethodTypeParams occurs when methods have type parameters.
	//
	// It cannot be encountered with an AST parsed using go/parser.
	InvalidMethodTypeParams

	// MisplacedTypeParam occurs when a type parameter is used in a place where
	// it is not permitted.
	//
	// Example:
	//  type T[P any] P
	//
	// Example:
	//  type T[P any] struct{ *P }
	MisplacedTypeParam

	// InvalidUnsafeSliceData occurs when unsafe.SliceData is called with
	// an argument that is not of slice type. It also occurs if it is used
	// in a package compiled for a language version before go1.20.
	//
	// Example:
	//  import "unsafe"
	//
	//  var x int
	//  var _ = unsafe.SliceData(x)
	InvalidUnsafeSliceData

	// InvalidUnsafeString occurs when unsafe.String is called with
	// a length argument that is not of integer type, negative, or
	// out of bounds. It also occurs if it is used in a package
	// compiled for a language version before go1.20.
	//
	// Example:
	//  import "unsafe"
	//
	//  var b [10]byte
	//  var _ = unsafe.String(&b[0], -1)
	InvalidUnsafeString

	// InvalidUnsafeStringData occurs if it is used in a package
	// compiled for a language version before go1.20.
	_ // not used anymore

)


================================================
FILE: internal/typesinternal/errorcode_string.go
================================================
// Code generated by "stringer -type=ErrorCode"; DO NOT EDIT.

package typesinternal

import "strconv"

func _() {
	// An "invalid array index" compiler error signifies that the constant values have changed.
	// Re-run the stringer command to generate them again.
	var x [1]struct{}
	_ = x[InvalidSyntaxTree - -1]
	_ = x[Test-1]
	_ = x[BlankPkgName-2]
	_ = x[MismatchedPkgName-3]
	_ = x[InvalidPkgUse-4]
	_ = x[BadImportPath-5]
	_ = x[BrokenImport-6]
	_ = x[ImportCRenamed-7]
	_ = x[UnusedImport-8]
	_ = x[InvalidInitCycle-9]
	_ = x[DuplicateDecl-10]
	_ = x[InvalidDeclCycle-11]
	_ = x[InvalidTypeCycle-12]
	_ = x[InvalidConstInit-13]
	_ = x[InvalidConstVal-14]
	_ = x[InvalidConstType-15]
	_ = x[UntypedNilUse-16]
	_ = x[WrongAssignCount-17]
	_ = x[UnassignableOperand-18]
	_ = x[NoNewVar-19]
	_ = x[MultiValAssignOp-20]
	_ = x[InvalidIfaceAssign-21]
	_ = x[InvalidChanAssign-22]
	_ = x[IncompatibleAssign-23]
	_ = x[UnaddressableFieldAssign-24]
	_ = x[NotAType-25]
	_ = x[InvalidArrayLen-26]
	_ = x[BlankIfaceMethod-27]
	_ = x[IncomparableMapKey-28]
	_ = x[InvalidIfaceEmbed-29]
	_ = x[InvalidPtrEmbed-30]
	_ = x[BadRecv-31]
	_ = x[InvalidRecv-32]
	_ = x[DuplicateFieldAndMethod-33]
	_ = x[DuplicateMethod-34]
	_ = x[InvalidBlank-35]
	_ = x[InvalidIota-36]
	_ = x[MissingInitBody-37]
	_ = x[InvalidInitSig-38]
	_ = x[InvalidInitDecl-39]
	_ = x[InvalidMainDecl-40]
	_ = x[TooManyValues-41]
	_ = x[NotAnExpr-42]
	_ = x[TruncatedFloat-43]
	_ = x[NumericOverflow-44]
	_ = x[UndefinedOp-45]
	_ = x[MismatchedTypes-46]
	_ = x[DivByZero-47]
	_ = x[NonNumericIncDec-48]
	_ = x[UnaddressableOperand-49]
	_ = x[InvalidIndirection-50]
	_ = x[NonIndexableOperand-51]
	_ = x[InvalidIndex-52]
	_ = x[SwappedSliceIndices-53]
	_ = x[NonSliceableOperand-54]
	_ = x[InvalidSliceExpr-55]
	_ = x[InvalidShiftCount-56]
	_ = x[InvalidShiftOperand-57]
	_ = x[InvalidReceive-58]
	_ = x[InvalidSend-59]
	_ = x[DuplicateLitKey-60]
	_ = x[MissingLitKey-61]
	_ = x[InvalidLitIndex-62]
	_ = x[OversizeArrayLit-63]
	_ = x[MixedStructLit-64]
	_ = x[InvalidStructLit-65]
	_ = x[MissingLitField-66]
	_ = x[DuplicateLitField-67]
	_ = x[UnexportedLitField-68]
	_ = x[InvalidLitField-69]
	_ = x[UntypedLit-70]
	_ = x[InvalidLit-71]
	_ = x[AmbiguousSelector-72]
	_ = x[UndeclaredImportedName-73]
	_ = x[UnexportedName-74]
	_ = x[UndeclaredName-75]
	_ = x[MissingFieldOrMethod-76]
	_ = x[BadDotDotDotSyntax-77]
	_ = x[NonVariadicDotDotDot-78]
	_ = x[MisplacedDotDotDot-79]
	_ = x[InvalidDotDotDotOperand-80]
	_ = x[InvalidDotDotDot-81]
	_ = x[UncalledBuiltin-82]
	_ = x[InvalidAppend-83]
	_ = x[InvalidCap-84]
	_ = x[InvalidClose-85]
	_ = x[InvalidCopy-86]
	_ = x[InvalidComplex-87]
	_ = x[InvalidDelete-88]
	_ = x[InvalidImag-89]
	_ = x[InvalidLen-90]
	_ = x[SwappedMakeArgs-91]
	_ = x[InvalidMake-92]
	_ = x[InvalidReal-93]
	_ = x[InvalidAssert-94]
	_ = x[ImpossibleAssert-95]
	_ = x[InvalidConversion-96]
	_ = x[InvalidUntypedConversion-97]
	_ = x[BadOffsetofSyntax-98]
	_ = x[InvalidOffsetof-99]
	_ = x[UnusedExpr-100]
	_ = x[UnusedVar-101]
	_ = x[MissingReturn-102]
	_ = x[WrongResultCount-103]
	_ = x[OutOfScopeResult-104]
	_ = x[InvalidCond-105]
	_ = x[InvalidPostDecl-106]
	_ = x[InvalidChanRange-107]
	_ = x[InvalidIterVar-108]
	_ = x[InvalidRangeExpr-109]
	_ = x[MisplacedBreak-110]
	_ = x[MisplacedContinue-111]
	_ = x[MisplacedFallthrough-112]
	_ = x[DuplicateCase-113]
	_ = x[DuplicateDefault-114]
	_ = x[BadTypeKeyword-115]
	_ = x[InvalidTypeSwitch-116]
	_ = x[InvalidExprSwitch-117]
	_ = x[InvalidSelectCase-118]
	_ = x[UndeclaredLabel-119]
	_ = x[DuplicateLabel-120]
	_ = x[MisplacedLabel-121]
	_ = x[UnusedLabel-122]
	_ = x[JumpOverDecl-123]
	_ = x[JumpIntoBlock-124]
	_ = x[InvalidMethodExpr-125]
	_ = x[WrongArgCount-126]
	_ = x[InvalidCall-127]
	_ = x[UnusedResults-128]
	_ = x[InvalidDefer-129]
	_ = x[InvalidGo-130]
	_ = x[BadDecl-131]
	_ = x[RepeatedDecl-132]
	_ = x[InvalidUnsafeAdd-133]
	_ = x[InvalidUnsafeSlice-134]
	_ = x[UnsupportedFeature-135]
	_ = x[NotAGenericType-136]
	_ = x[WrongTypeArgCount-137]
	_ = x[CannotInferTypeArgs-138]
	_ = x[InvalidTypeArg-139]
	_ = x[InvalidInstanceCycle-140]
	_ = x[InvalidUnion-141]
	_ = x[MisplacedConstraintIface-142]
	_ = x[InvalidMethodTypeParams-143]
	_ = x[MisplacedTypeParam-144]
	_ = x[InvalidUnsafeSliceData-145]
	_ = x[InvalidUnsafeString-146]
}

const (
	_ErrorCode_name_0 = "InvalidSyntaxTree"
	_ErrorCode_name_1 = "TestBlankPkgNameMismatchedPkgNameInvalidPkgUseBadImportPathBrokenImportImportCRenamedUnusedImportInvalidInitCycleDuplicateDeclInvalidDeclCycleInvalidTypeCycleInvalidConstInitInvalidConstValInvalidConstTypeUntypedNilUseWrongAssignCountUnassignableOperandNoNewVarMultiValAssignOpInvalidIfaceAssignInvalidChanAssignIncompatibleAssignUnaddressableFieldAssignNotATypeInvalidArrayLenBlankIfaceMethodIncomparableMapKeyInvalidIfaceEmbedInvalidPtrEmbedBadRecvInvalidRecvDuplicateFieldAndMethodDuplicateMethodInvalidBlankInvalidIotaMissingInitBodyInvalidInitSigInvalidInitDeclInvalidMainDeclTooManyValuesNotAnExprTruncatedFloatNumericOverflowUndefinedOpMismatchedTypesDivByZeroNonNumericIncDecUnaddressableOperandInvalidIndirectionNonIndexableOperandInvalidIndexSwappedSliceIndicesNonSliceableOperandInvalidSliceExprInvalidShiftCountInvalidShiftOperandInvalidReceiveInvalidSendDuplicateLitKeyMissingLitKeyInvalidLitIndexOversizeArrayLitMixedStructLitInvalidStructLitMissingLitFieldDuplicateLitFieldUnexportedLitFieldInvalidLitFieldUntypedLitInvalidLitAmbiguousSelectorUndeclaredImportedNameUnexportedNameUndeclaredNameMissingFieldOrMethodBadDotDotDotSyntaxNonVariadicDotDotDotMisplacedDotDotDotInvalidDotDotDotOperandInvalidDotDotDotUncalledBuiltinInvalidAppendInvalidCapInvalidCloseInvalidCopyInvalidComplexInvalidDeleteInvalidImagInvalidLenSwappedMakeArgsInvalidMakeInvalidRealInvalidAssertImpossibleAssertInvalidConversionInvalidUntypedConversionBadOffsetofSyntaxInvalidOffsetofUnusedExprUnusedVarMissingReturnWrongResultCountOutOfScopeResultInvalidCondInvalidPostDeclInvalidChanRangeInvalidIterVarInvalidRangeExprMisplacedBreakMisplacedContinueMisplacedFallthroughDuplicateCaseDuplicateDefaultBadTypeKeywordInvalidTypeSwitchInvalidExprSwitchInvalidSelectCaseUndeclaredLabelDuplicateLabelMisplacedLabelUnusedLabelJumpOverDeclJumpIntoBlockInvalidMethodExprWrongArgCountInvalidCallUnusedResultsInvalidDeferInvalidGoBadDeclRepeatedDeclInvalidUnsafeAddInvalidUnsafeSliceUnsupportedFeatureNotAGenericTypeWrongTypeArgCountCannotInferTypeArgsInvalidTypeArgInvalidInstanceCycleInvalidUnionMisplacedConstraintIfaceInvalidMethodTypeParamsMisplacedTypeParamInvalidUnsafeSliceDataInvalidUnsafeString"
)

var (
	_ErrorCode_index_1 = [...]uint16{0, 4, 16, 33, 46, 59, 71, 85, 97, 113, 126, 142, 158, 174, 189, 205, 218, 234, 253, 261, 277, 295, 312, 330, 354, 362, 377, 393, 411, 428, 443, 450, 461, 484, 499, 511, 522, 537, 551, 566, 581, 594, 603, 617, 632, 643, 658, 667, 683, 703, 721, 740, 752, 771, 790, 806, 823, 842, 856, 867, 882, 895, 910, 926, 940, 956, 971, 988, 1006, 1021, 1031, 1041, 1058, 1080, 1094, 1108, 1128, 1146, 1166, 1184, 1207, 1223, 1238, 1251, 1261, 1273, 1284, 1298, 1311, 1322, 1332, 1347, 1358, 1369, 1382, 1398, 1415, 1439, 1456, 1471, 1481, 1490, 1503, 1519, 1535, 1546, 1561, 1577, 1591, 1607, 1621, 1638, 1658, 1671, 1687, 1701, 1718, 1735, 1752, 1767, 1781, 1795, 1806, 1818, 1831, 1848, 1861, 1872, 1885, 1897, 1906, 1913, 1925, 1941, 1959, 1977, 1992, 2009, 2028, 2042, 2062, 2074, 2098, 2121, 2139, 2161, 2180}
)

func (i ErrorCode) String() string {
	switch {
	case i == -1:
		return _ErrorCode_name_0
	case 1 <= i && i <= 146:
		i -= 1
		return _ErrorCode_name_1[_ErrorCode_index_1[i]:_ErrorCode_index_1[i+1]]
	default:
		return "ErrorCode(" + strconv.FormatInt(int64(i), 10) + ")"
	}
}


================================================
FILE: internal/typesinternal/errorcode_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal_test

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/parser"
	"go/token"
	"go/types"
	"path/filepath"
	"runtime"
	"sort"
	"strings"
	"testing"
)

func TestErrorCodes(t *testing.T) {
	t.Skip("unskip this test to verify the correctness of errorcode.go for the current Go version")

	// For older go versions, this file was src/go/types/errorcodes.go.
	stdPath := filepath.Join(runtime.GOROOT(), "src", "internal", "types", "errors", "codes.go")
	stdCodes, err := loadCodes(stdPath)
	if err != nil {
		t.Fatalf("loading std codes: %v", err)
	}

	localPath := "errorcode.go"
	localCodes, err := loadCodes(localPath)
	if err != nil {
		t.Fatalf("loading local codes: %v", err)
	}

	// Verify that all std codes are present, with the correct value.
	type codeVal struct {
		Name  string
		Value int64
	}
	var byValue []codeVal
	for k, v := range stdCodes {
		byValue = append(byValue, codeVal{k, v})
	}
	sort.Slice(byValue, func(i, j int) bool {
		return byValue[i].Value < byValue[j].Value
	})

	localLookup := make(map[int64]string)
	for k, v := range localCodes {
		if _, ok := localLookup[v]; ok {
			t.Errorf("duplicate error code value %d", v)
		}
		localLookup[v] = k
	}

	for _, std := range byValue {
		local, ok := localCodes[std.Name]
		if !ok {
			if v, ok := localLookup[std.Value]; ok {
				t.Errorf("Missing code for %s (code %d is %s)", std.Name, std.Value, v)
			} else {
				t.Errorf("Missing code for %s", std.Name)
			}
		}
		if local != std.Value {
			t.Errorf("Mismatching value for %s: got %d, but stdlib has %d", std.Name, local, std.Value)
		}
	}
}

// loadCodes loads all constant values found in filepath.
//
// The given file must type-check cleanly as a standalone file.
func loadCodes(filepath string) (map[string]int64, error) {
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, filepath, nil, 0)
	if err != nil {
		return nil, err
	}
	var config types.Config
	pkg, err := config.Check("p", fset, []*ast.File{f}, nil)
	if err != nil {
		return nil, err
	}

	codes := make(map[string]int64)
	for _, name := range pkg.Scope().Names() {
		obj := pkg.Scope().Lookup(name)
		c, ok := obj.(*types.Const)
		if !ok {
			continue
		}
		name := strings.TrimPrefix(name, "_") // compatibility with earlier go versions
		codes[name], ok = constant.Int64Val(c.Val())
		if !ok {
			return nil, fmt.Errorf("non integral value %v for %s", c.Val(), name)
		}
	}
	if len(codes) < 100 {
		return nil, fmt.Errorf("sanity check: got %d codes but expected at least 100", len(codes))
	}
	return codes, nil
}


================================================
FILE: internal/typesinternal/fx.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"go/ast"
	"go/token"
	"go/types"
)

// NoEffects reports whether the expression has no side effects, i.e., it
// does not modify the memory state. This function is conservative: it may
// return false even when the expression has no effect.
func NoEffects(info *types.Info, expr ast.Expr) bool {
	noEffects := true
	ast.Inspect(expr, func(n ast.Node) bool {
		switch v := n.(type) {
		case nil, *ast.Ident, *ast.BasicLit, *ast.BinaryExpr, *ast.ParenExpr,
			*ast.SelectorExpr, *ast.IndexExpr, *ast.SliceExpr, *ast.TypeAssertExpr,
			*ast.StarExpr, *ast.CompositeLit,
			// non-expressions that may appear within expressions
			*ast.KeyValueExpr,
			*ast.FieldList,
			*ast.Field,
			*ast.Ellipsis,
			*ast.IndexListExpr:
			// No effect.

		case *ast.ArrayType,
			*ast.StructType,
			*ast.ChanType,
			*ast.FuncType,
			*ast.MapType,
			*ast.InterfaceType:
			// Type syntax: no effects, recursively.
			// Prune descent.
			return false

		case *ast.UnaryExpr:
			// Channel send <-ch has effects.
			if v.Op == token.ARROW {
				noEffects = false
			}

		case *ast.CallExpr:
			// Type conversion has no effects.
			if !info.Types[v.Fun].IsType() {
				if CallsPureBuiltin(info, v) {
					// A call such as len(e) has no effects of its
					// own, though the subexpression e might.
				} else {
					noEffects = false
				}
			}

		case *ast.FuncLit:
			// A FuncLit has no effects, but do not descend into it.
			return false

		default:
			// All other expressions have effects
			noEffects = false
		}

		return noEffects
	})
	return noEffects
}

// CallsPureBuiltin reports whether call is a call of a built-in
// function that is a pure computation over its operands (analogous to
// a + operator). Because it does not depend on program state, it may
// be evaluated at any point--though not necessarily at multiple
// points (consider new, make).
func CallsPureBuiltin(info *types.Info, call *ast.CallExpr) bool {
	if id, ok := ast.Unparen(call.Fun).(*ast.Ident); ok {
		if b, ok := info.ObjectOf(id).(*types.Builtin); ok {
			switch b.Name() {
			case "len", "cap", "complex", "imag", "real", "make", "new", "max", "min":
				return true
			}
			// Not: append clear close copy delete panic print println recover
		}
	}
	return false
}


================================================
FILE: internal/typesinternal/fx_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/typesinternal"
)

func TestNoEffects(t *testing.T) {
	src := `package p

type T int

type G[P any] int

func _() {
	var x int
	_ = T(x)
	_ = G[int](x)
}
`
	fset := token.NewFileSet()
	file, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err)
	}
	var conf types.Config
	info := &types.Info{
		Types: make(map[ast.Expr]types.TypeAndValue),
	}
	_, err = conf.Check("", fset, []*ast.File{file}, info)
	if err != nil {
		t.Fatal(err)
	}
	ast.Inspect(file, func(node ast.Node) bool {
		call, ok := node.(*ast.CallExpr)
		if !ok {
			return true
		}
		if !typesinternal.NoEffects(info, call) {
			t.Errorf("NoEffects(%s) = false", types.ExprString(call))
		}
		return true
	})
}


================================================
FILE: internal/typesinternal/isnamed.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"go/types"
	"slices"
)

// IsTypeNamed reports whether t is (or is an alias for) a
// package-level defined type with the given package path and one of
// the given names. It returns false if t is nil.
//
// This function avoids allocating the concatenation of "pkg.Name",
// which is important for the performance of syntax matching.
func IsTypeNamed(t types.Type, pkgPath string, names ...string) bool {
	if named, ok := types.Unalias(t).(*types.Named); ok {
		tname := named.Obj()
		return tname != nil &&
			IsPackageLevel(tname) &&
			tname.Pkg().Path() == pkgPath &&
			slices.Contains(names, tname.Name())
	}
	return false
}

// IsPointerToNamed reports whether t is (or is an alias for) a pointer to a
// package-level defined type with the given package path and one of the given
// names. It returns false if t is not a pointer type.
func IsPointerToNamed(t types.Type, pkgPath string, names ...string) bool {
	r := Unpointer(t)
	if r == t {
		return false
	}
	return IsTypeNamed(r, pkgPath, names...)
}

// IsFunctionNamed reports whether obj is a package-level function
// defined in the given package and has one of the given names.
// It returns false if obj is nil.
//
// This function avoids allocating the concatenation of "pkg.Name",
// which is important for the performance of syntax matching.
func IsFunctionNamed(obj types.Object, pkgPath string, names ...string) bool {
	f, ok := obj.(*types.Func)
	return ok &&
		IsPackageLevel(obj) &&
		f.Pkg().Path() == pkgPath &&
		f.Signature().Recv() == nil &&
		slices.Contains(names, f.Name())
}

// IsMethodNamed reports whether obj is a method defined on a
// package-level type with the given package and type name, and has
// one of the given names. It returns false if obj is nil.
//
// This function avoids allocating the concatenation of "pkg.TypeName.Name",
// which is important for the performance of syntax matching.
func IsMethodNamed(obj types.Object, pkgPath string, typeName string, names ...string) bool {
	if fn, ok := obj.(*types.Func); ok {
		if recv := fn.Signature().Recv(); recv != nil {
			_, T := ReceiverNamed(recv)
			return T != nil &&
				IsTypeNamed(T, pkgPath, typeName) &&
				slices.Contains(names, fn.Name())
		}
	}
	return false
}


================================================
FILE: internal/typesinternal/qualifier.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"go/ast"
	"go/types"
	"strconv"
)

// FileQualifier returns a [types.Qualifier] function that qualifies
// imported symbols appropriately based on the import environment of a given
// file.
// If the same package is imported multiple times, the last appearance is
// recorded.
//
// TODO(adonovan): this function ignores the effect of shadowing. It
// should accept a [token.Pos] and a [types.Info] and compute only the
// set of imports that are not shadowed at that point, analogous to
// [analysis.AddImport]. It could also compute (as a side
// effect) the set of additional imports required to ensure that there
// is an accessible import for each necessary package, making it
// converge even more closely with AddImport.
func FileQualifier(f *ast.File, pkg *types.Package) types.Qualifier {
	// Construct mapping of import paths to their defined names.
	// It is only necessary to look at renaming imports.
	imports := make(map[string]string)
	for _, imp := range f.Imports {
		if imp.Name != nil && imp.Name.Name != "_" {
			path, _ := strconv.Unquote(imp.Path.Value)
			imports[path] = imp.Name.Name
		}
	}

	// Define qualifier to replace full package paths with names of the imports.
	return func(p *types.Package) string {
		if p == nil || p == pkg {
			return ""
		}

		if name, ok := imports[p.Path()]; ok {
			if name == "." {
				return ""
			} else {
				return name
			}
		}

		// If there is no local renaming, fall back to the package name.
		return p.Name()
	}
}


================================================
FILE: internal/typesinternal/recv.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"go/types"
)

// ReceiverNamed returns the named type (if any) associated with the
// type of recv, which may be of the form N or *N, or aliases thereof.
// It also reports whether a Pointer was present.
//
// The named result may be nil if recv is from a method on an
// anonymous interface or struct types or in ill-typed code.
func ReceiverNamed(recv *types.Var) (isPtr bool, named *types.Named) {
	t := recv.Type()
	if ptr, ok := types.Unalias(t).(*types.Pointer); ok {
		isPtr = true
		t = ptr.Elem()
	}
	named, _ = types.Unalias(t).(*types.Named)
	return
}

// Unpointer returns T given *T or an alias thereof.
// For all other types it is the identity function.
// It does not look at underlying types.
// The result may be an alias.
//
// Use this function to strip off the optional pointer on a receiver
// in a field or method selection, without losing the named type
// (which is needed to compute the method set).
//
// See also [typeparams.MustDeref], which removes one level of
// indirection from the type, regardless of named types (analogous to
// a LOAD instruction).
func Unpointer(t types.Type) types.Type {
	if ptr, ok := types.Unalias(t).(*types.Pointer); ok {
		return ptr.Elem()
	}
	return t
}


================================================
FILE: internal/typesinternal/toonew.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"go/types"

	"golang.org/x/tools/internal/stdlib"
	"golang.org/x/tools/internal/versions"
)

// TooNewStdSymbols computes the set of package-level symbols
// exported by pkg that are not available at the specified version.
// The result maps each symbol to its minimum version.
//
// The pkg is allowed to contain type errors.
func TooNewStdSymbols(pkg *types.Package, version string) map[types.Object]string {
	disallowed := make(map[types.Object]string)

	// Pass 1: package-level symbols.
	symbols := stdlib.PackageSymbols[pkg.Path()]
	for _, sym := range symbols {
		symver := sym.Version.String()
		if versions.Before(version, symver) {
			switch sym.Kind {
			case stdlib.Func, stdlib.Var, stdlib.Const, stdlib.Type:
				disallowed[pkg.Scope().Lookup(sym.Name)] = symver
			}
		}
	}

	// Pass 2: fields and methods.
	//
	// We allow fields and methods if their associated type is
	// disallowed, as otherwise we would report false positives
	// for compatibility shims. Consider:
	//
	//   //go:build go1.22
	//   type T struct { F std.Real } // correct new API
	//
	//   //go:build !go1.22
	//   type T struct { F fake } // shim
	//   type fake struct { ... }
	//   func (fake) M () {}
	//
	// These alternative declarations of T use either the std.Real
	// type, introduced in go1.22, or a fake type, for the field
	// F. (The fakery could be arbitrarily deep, involving more
	// nested fields and methods than are shown here.) Clients
	// that use the compatibility shim T will compile with any
	// version of go, whether older or newer than go1.22, but only
	// the newer version will use the std.Real implementation.
	//
	// Now consider a reference to method M in new(T).F.M() in a
	// module that requires a minimum of go1.21. The analysis may
	// occur using a version of Go higher than 1.21, selecting the
	// first version of T, so the method M is Real.M. This would
	// spuriously cause the analyzer to report a reference to a
	// too-new symbol even though this expression compiles just
	// fine (with the fake implementation) using go1.21.
	for _, sym := range symbols {
		symVersion := sym.Version.String()
		if !versions.Before(version, symVersion) {
			continue // allowed
		}

		var obj types.Object
		switch sym.Kind {
		case stdlib.Field:
			typename, name := sym.SplitField()
			if t := pkg.Scope().Lookup(typename); t != nil && disallowed[t] == "" {
				obj, _, _ = types.LookupFieldOrMethod(t.Type(), false, pkg, name)
			}

		case stdlib.Method:
			ptr, recvname, name := sym.SplitMethod()
			if t := pkg.Scope().Lookup(recvname); t != nil && disallowed[t] == "" {
				obj, _, _ = types.LookupFieldOrMethod(t.Type(), ptr, pkg, name)
			}
		}
		if obj != nil {
			disallowed[obj] = symVersion
		}
	}

	return disallowed
}


================================================
FILE: internal/typesinternal/typeindex/typeindex.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typeindex provides an [Index] of type information for a
// package, allowing efficient lookup of, say, whether a given symbol
// is referenced and, if so, where from; or of the [inspector.Cursor] for
// the declaration of a particular [types.Object] symbol.
package typeindex

import (
	"encoding/binary"
	"go/ast"
	"go/types"
	"iter"

	"golang.org/x/tools/go/ast/edge"
	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typesinternal"
)

// New constructs an Index for the package of type-annotated syntax
//
// TODO(adonovan): accept a FileSet too?
// We regret not requiring one in inspector.New.
func New(inspect *inspector.Inspector, pkg *types.Package, info *types.Info) *Index {
	ix := &Index{
		inspect:  inspect,
		info:     info,
		packages: make(map[string]*types.Package),
		def:      make(map[types.Object]inspector.Cursor),
		uses:     make(map[types.Object]*uses),
	}

	addPackage := func(pkg2 *types.Package) {
		if pkg2 != nil && pkg2 != pkg {
			ix.packages[pkg2.Path()] = pkg2
		}
	}

	for cur := range inspect.Root().Preorder((*ast.ImportSpec)(nil), (*ast.Ident)(nil)) {
		switch n := cur.Node().(type) {
		case *ast.ImportSpec:
			// Index direct imports, including blank ones.
			if pkgname := info.PkgNameOf(n); pkgname != nil {
				addPackage(pkgname.Imported())
			}

		case *ast.Ident:
			// Index all defining and using identifiers.
			if obj := info.Defs[n]; obj != nil {
				ix.def[obj] = cur
			}

			if obj := info.Uses[n]; obj != nil {
				// Index indirect dependencies (via fields and methods).
				if !typesinternal.IsPackageLevel(obj) {
					addPackage(obj.Pkg())
				}

				for {
					us, ok := ix.uses[obj]
					if !ok {
						us = &uses{}
						us.code = us.initial[:0]
						ix.uses[obj] = us
					}
					delta := cur.Index() - us.last
					if delta < 0 {
						panic("non-monotonic")
					}
					us.code = binary.AppendUvarint(us.code, uint64(delta))
					us.last = cur.Index()

					// If n is a selection of a field or method of an instantiated
					// type, also record a use of the generic field or method.
					obj, ok = objectOrigin(obj)
					if !ok {
						break
					}
				}
			}
		}
	}
	return ix
}

// objectOrigin returns the generic object for obj if it is a field or
// method of an instantied type; zero otherwise.
//
// (This operation is appropriate only for selections.
// Lexically resolved references always resolve to the generic.
// Although Named and Alias types also use Origin to express
// an instance/generic distinction, that's in the domain
// of Types; their TypeName objects always refer to the generic.)
func objectOrigin(obj types.Object) (types.Object, bool) {
	var origin types.Object
	switch obj := obj.(type) {
	case *types.Func:
		if obj.Signature().Recv() != nil {
			origin = obj.Origin() // G[int].method -> G[T].method
		}
	case *types.Var:
		if obj.IsField() {
			origin = obj.Origin() // G[int].field  -> G[T].field
		}
	}
	if origin != nil && origin != obj {
		return origin, true
	}
	return nil, false
}

// An Index holds an index mapping [types.Object] symbols to their syntax.
// In effect, it is the inverse of [types.Info].
type Index struct {
	inspect  *inspector.Inspector
	info     *types.Info
	packages map[string]*types.Package         // packages of all symbols referenced from this package
	def      map[types.Object]inspector.Cursor // Cursor of *ast.Ident that defines the Object
	uses     map[types.Object]*uses            // Cursors of *ast.Idents that use the Object
}

// A uses holds the list of Cursors of Idents that use a given symbol.
//
// The Uses map of [types.Info] is substantial, so it pays to compress
// its inverse mapping here, both in space and in CPU due to reduced
// allocation. A Cursor is 2 words; a Cursor.Index is 4 bytes; but
// since Cursors are naturally delivered in ascending order, we can
// use varint-encoded deltas at a cost of only ~1.7-2.2 bytes per use.
//
// Many variables have only one or two uses, so their encoded uses may
// fit in the 4 bytes of initial, saving further CPU and space
// essentially for free since the struct's size class is 4 words.
type uses struct {
	code    []byte  // varint-encoded deltas of successive Cursor.Index values
	last    int32   // most recent Cursor.Index value; used during encoding
	initial [4]byte // use slack in size class as initial space for code
}

// Uses returns the sequence of Cursors of [*ast.Ident]s in this package
// that refer to obj. If obj is nil, the sequence is empty.
//
// Uses, unlike the Uses field of [types.Info], records additional
// entries mapping fields and methods of generic types to references
// through their corresponding instantiated objects.
func (ix *Index) Uses(obj types.Object) iter.Seq[inspector.Cursor] {
	return func(yield func(inspector.Cursor) bool) {
		if uses := ix.uses[obj]; uses != nil {
			var last int32
			for code := uses.code; len(code) > 0; {
				delta, n := binary.Uvarint(code)
				last += int32(delta)
				if !yield(ix.inspect.At(last)) {
					return
				}
				code = code[n:]
			}
		}
	}
}

// Used reports whether any of the specified objects are used, in
// other words, obj != nil && Uses(obj) is non-empty for some obj in objs.
//
// (This treatment of nil allows Used to be called directly on the
// result of [Index.Object] so that analyzers can conveniently skip
// packages that don't use a symbol of interest.)
func (ix *Index) Used(objs ...types.Object) bool {
	for _, obj := range objs {
		if obj != nil && ix.uses[obj] != nil {
			return true
		}
	}
	return false
}

// Def returns the Cursor of the [*ast.Ident] in this package
// that declares the specified object, if any.
func (ix *Index) Def(obj types.Object) (inspector.Cursor, bool) {
	cur, ok := ix.def[obj]
	return cur, ok
}

// Package returns the package of the specified path,
// or nil if it is not referenced from this package.
func (ix *Index) Package(path string) *types.Package {
	return ix.packages[path]
}

// Object returns the package-level symbol name within the package of
// the specified path, or nil if the package or symbol does not exist
// or is not visible from this package.
func (ix *Index) Object(path, name string) types.Object {
	if pkg := ix.Package(path); pkg != nil {
		return pkg.Scope().Lookup(name)
	}
	return nil
}

// Selection returns the named method or field belonging to the
// package-level type returned by Object(path, typename).
func (ix *Index) Selection(path, typename, name string) types.Object {
	if obj := ix.Object(path, typename); obj != nil {
		if tname, ok := obj.(*types.TypeName); ok {
			obj, _, _ := types.LookupFieldOrMethod(tname.Type(), true, obj.Pkg(), name)
			return obj
		}
	}
	return nil
}

// Calls returns the sequence of cursors for *ast.CallExpr nodes that
// call the specified callee, as defined by [typeutil.Callee].
// If callee is nil, the sequence is empty.
func (ix *Index) Calls(callee types.Object) iter.Seq[inspector.Cursor] {
	return func(yield func(inspector.Cursor) bool) {
		for cur := range ix.Uses(callee) {
			ek := cur.ParentEdgeKind()

			// The call may be of the form f() or x.f(),
			// optionally with parens; ascend from f to call.
			//
			// It is tempting but wrong to use the first
			// CallExpr ancestor: we have to make sure the
			// ident is in the CallExpr.Fun position, otherwise
			// f(f, f) would have two spurious matches.
			// Avoiding Enclosing is also significantly faster.

			// inverse unparen: f -> (f)
			for ek == edge.ParenExpr_X {
				cur = cur.Parent()
				ek = cur.ParentEdgeKind()
			}

			// ascend selector: f -> x.f
			if ek == edge.SelectorExpr_Sel {
				cur = cur.Parent()
				ek = cur.ParentEdgeKind()
			}

			// inverse unparen again
			for ek == edge.ParenExpr_X {
				cur = cur.Parent()
				ek = cur.ParentEdgeKind()
			}

			// ascend from f or x.f to call
			if ek == edge.CallExpr_Fun {
				curCall := cur.Parent()
				call := curCall.Node().(*ast.CallExpr)
				if typeutil.Callee(ix.info, call) == callee {
					if !yield(curCall) {
						return
					}
				}
			}
		}
	}
}


================================================
FILE: internal/typesinternal/typeindex/typeindex_test.go
================================================
// Copyright 2025 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typeindex_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"slices"
	"testing"

	"golang.org/x/tools/go/ast/inspector"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/typesinternal/typeindex"
)

func TestIndex(t *testing.T) {
	testenv.NeedsGoPackages(t)
	var (
		pkg        = loadNetHTTP(t)
		inspect    = inspector.New(pkg.Syntax)
		index      = typeindex.New(inspect, pkg.Types, pkg.TypesInfo)
		fmtSprintf = index.Object("fmt", "Sprintf")
	)

	// Gather calls and uses of fmt.Sprintf in net/http.
	var (
		wantUses  []*ast.Ident
		wantCalls []*ast.CallExpr
	)
	for n := range inspect.PreorderSeq((*ast.CallExpr)(nil), (*ast.Ident)(nil)) {
		switch n := n.(type) {
		case *ast.CallExpr:
			if typeutil.Callee(pkg.TypesInfo, n) == fmtSprintf {
				wantCalls = append(wantCalls, n)
			}
		case *ast.Ident:
			if pkg.TypesInfo.Uses[n] == fmtSprintf {
				wantUses = append(wantUses, n)
			}
		}
	}
	// sanity check (expect about 60 of each)
	if wantUses == nil || wantCalls == nil {
		t.Fatalf("no calls or uses of fmt.Sprintf in net/http")
	}

	var (
		gotUses  []*ast.Ident
		gotCalls []*ast.CallExpr
	)
	for curId := range index.Uses(fmtSprintf) {
		gotUses = append(gotUses, curId.Node().(*ast.Ident))
	}
	for curCall := range index.Calls(fmtSprintf) {
		gotCalls = append(gotCalls, curCall.Node().(*ast.CallExpr))
	}

	if !slices.Equal(gotUses, wantUses) {
		t.Errorf("index.Uses(fmt.Sprintf) = %v, want %v", gotUses, wantUses)
	}
	if !slices.Equal(gotCalls, wantCalls) {
		t.Errorf("index.Calls(fmt.Sprintf) = %v, want %v", gotCalls, wantCalls)
	}
}

func loadNetHTTP(tb testing.TB) *packages.Package {
	cfg := &packages.Config{Mode: packages.LoadSyntax}
	pkgs, err := packages.Load(cfg, "net/http")
	if err != nil {
		tb.Fatal(err)
	}
	return pkgs[0]
}

func BenchmarkIndex(b *testing.B) {
	// Load net/http, a large package, and find calls to net.Dial.
	//
	// There is currently exactly one, which provides an extreme
	// demonstration of the performance advantage of the Index.
	//
	// Index construction costs approximately 7x the cursor
	// traversal, so it breaks even when it replaces 7 passes.
	// The cost of index lookup is approximately zero.
	pkg := loadNetHTTP(b)

	// Build the Inspector (~2.8ms).
	var inspect *inspector.Inspector
	b.Run("inspector.New", func(b *testing.B) {
		for b.Loop() {
			inspect = inspector.New(pkg.Syntax)
		}
	})

	// Build the Index (~6.6ms).
	var index *typeindex.Index
	b.Run("typeindex.New", func(b *testing.B) {
		b.ReportAllocs() // 2.48MB/op
		for b.Loop() {
			index = typeindex.New(inspect, pkg.Types, pkg.TypesInfo)
		}
	})

	target := index.Object("net", "Dial")

	var countA, countB, countC int

	// unoptimized inspect implementation (~1.6ms, 1x)
	b.Run("inspect", func(b *testing.B) {
		for b.Loop() {
			countA = 0
			for _, file := range pkg.Syntax {
				ast.Inspect(file, func(n ast.Node) bool {
					if call, ok := n.(*ast.CallExpr); ok {
						if typeutil.Callee(pkg.TypesInfo, call) == target {
							countA++
						}
					}
					return true
				})
			}
		}
	})
	if countA == 0 {
		b.Errorf("target %v not found", target)
	}

	// unoptimized cursor implementation (~390us, 4x faster)
	b.Run("cursor", func(b *testing.B) {
		for b.Loop() {
			countB = 0
			for curCall := range inspect.Root().Preorder((*ast.CallExpr)(nil)) {
				call := curCall.Node().(*ast.CallExpr)
				if typeutil.Callee(pkg.TypesInfo, call) == target {
					countB++
				}
			}
		}
	})

	// indexed implementation (~120ns, >10,000x faster)
	b.Run("index", func(b *testing.B) {
		for b.Loop() {
			countC = 0
			for range index.Calls(target) {
				countC++
			}
		}
	})

	if countA != countB || countA != countC {
		b.Fatalf("inconsistent results (inspect=%d, cursor=%d, index=%d)", countA, countB, countC)
	}
}

// TestOrigin checks that index.Uses on field or method of a generic
// type reports references to its instantiations.
// Lexical references (to functions, types, and aliases) always
// resolve to the generic; there is no Origin distinction.
func TestOrigin(t *testing.T) {
	// Each nonblank declared name must have at least one use.
	for _, src := range []string{
		`
package alias
type A[T any] = *T
var _ A[int]`,
		`
package localalias
func _[T any]() {
	type A[U any] = *U
	var _ A[T]
}`,
		`
package named
type Named[_ any] int
var _ Named[int]`,
		`
package localnamed
func _[T any]() {
	type N[U any] struct { f U }
	_ = N[T]{}.f
}`,
		`
package field
type Named[T any] struct { field T }
var _ = Named[int]{}.field`,
		`
package function
func F[T any](T) {}
var _ = F[int]`,
		`
package method
type Named[_ any] int
func (Named[T]) method(T) {}
var _ = Named[int].method`,
		`
package uninstantiatedmethod
type Named[_ any] int
func (Named[_]) f() {}
func (Named[T]) g() { Named[T](0).f() }
func (n Named[_]) _() { n.g() }`,
	} {
		// parse
		fset := token.NewFileSet()
		f, _ := parser.ParseFile(fset, "", src, parser.PackageClauseOnly)
		t.Run(f.Name.Name, func(t *testing.T) {
			f, _ := parser.ParseFile(fset, "", src, 0)
			files := []*ast.File{f}

			// typecheck
			info := &types.Info{
				Defs: make(map[*ast.Ident]types.Object),
				Uses: make(map[*ast.Ident]types.Object),
			}
			pkg, err := new(types.Config).Check(f.Name.Name, fset, files, info)
			if err != nil {
				t.Fatal(err)
			}

			// index
			var (
				inspect = inspector.New(files)
				index   = typeindex.New(inspect, pkg, info)
			)

			// check Def/Uses of all objects
			for id := range inspect.PreorderSeq((*ast.Ident)(nil)) {
				id := id.(*ast.Ident)
				if obj := info.Defs[id]; obj != nil && id.Name != "_" {
					t.Logf("%T %s @ %s", obj, id.Name, fset.Position(id.Pos()))

					// check Def
					if curDef, ok := index.Def(obj); !ok {
						t.Errorf("- index.Def missing")
					} else if curDef.Node() != id {
						t.Errorf("- index.Def wrong: @%s", fset.Position(curDef.Node().Pos()))
					}

					// check Uses is nonempty
					ok := false
					for use := range index.Uses(obj) {
						t.Logf("- index.Use at %s", fset.Position(use.Node().Pos()))
						ok = true
					}
					if !ok {
						t.Errorf("- no index.Uses")
					}
				}
			}
		})
	}
}


================================================
FILE: internal/typesinternal/types.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package typesinternal provides helpful operators for dealing with
// go/types:
//
//   - operators for querying typed syntax trees (e.g. [Imports], [IsFunctionNamed]);
//   - functions for converting types to strings or syntax (e.g. [TypeExpr], FileQualifier]);
//   - helpers for working with the [go/types] API (e.g. [NewTypesInfo]);
//   - access to internal go/types APIs that are not yet
//     exported (e.g. [SetUsesCgo], [ErrorCodeStartEnd], [VarKind]); and
//   - common algorithms related to types (e.g. [TooNewStdSymbols]).
//
// See also:
//   - [golang.org/x/tools/internal/astutil], for operations on untyped syntax;
//   - [golang.org/x/tools/internal/analysisinernal], for helpers for analyzers;
//   - [golang.org/x/tools/internal/refactor], for operators to compute text edits.
package typesinternal

import (
	"go/ast"
	"go/token"
	"go/types"
	"reflect"

	"golang.org/x/tools/go/ast/inspector"
)

func SetUsesCgo(conf *types.Config) bool {
	v := reflect.ValueOf(conf).Elem()

	f := v.FieldByName("go115UsesCgo")
	if !f.IsValid() {
		f = v.FieldByName("UsesCgo")
		if !f.IsValid() {
			return false
		}
	}

	*(*bool)(f.Addr().UnsafePointer()) = true

	return true
}

// ErrorCodeStartEnd extracts additional information from types.Error values
// generated by Go version 1.16 and later: the error code, start position, and
// end position. If all positions are valid, start <= err.Pos <= end.
//
// If the data could not be read, the final result parameter will be false.
//
// TODO(adonovan): eliminate start/end when proposal #71803 is accepted.
func ErrorCodeStartEnd(err types.Error) (code ErrorCode, start, end token.Pos, ok bool) {
	var data [3]int
	// By coincidence all of these fields are ints, which simplifies things.
	v := reflect.ValueOf(err)
	for i, name := range []string{"go116code", "go116start", "go116end"} {
		f := v.FieldByName(name)
		if !f.IsValid() {
			return 0, 0, 0, false
		}
		data[i] = int(f.Int())
	}
	return ErrorCode(data[0]), token.Pos(data[1]), token.Pos(data[2]), true
}

// NameRelativeTo returns a types.Qualifier that qualifies members of
// all packages other than pkg, using only the package name.
// (By contrast, [types.RelativeTo] uses the complete package path,
// which is often excessive.)
//
// If pkg is nil, it is equivalent to [*types.Package.Name].
//
// TODO(adonovan): all uses of this with TypeString should be
// eliminated when https://go.dev/issues/75604 is resolved.
func NameRelativeTo(pkg *types.Package) types.Qualifier {
	return func(other *types.Package) string {
		if pkg != nil && pkg == other {
			return "" // same package; unqualified
		}
		return other.Name()
	}
}

// TypeNameFor returns the type name symbol for the specified type, if
// it is a [*types.Alias], [*types.Named], [*types.TypeParam], or a
// [*types.Basic] representing a type.
//
// For all other types, and for Basic types representing a builtin,
// constant, or nil, it returns nil. Be careful not to convert the
// resulting nil pointer to a [types.Object]!
//
// If t is the type of a constant, it may be an "untyped" type, which
// has no TypeName. To access the name of such types (e.g. "untyped
// int"), use [types.Basic.Name].
func TypeNameFor(t types.Type) *types.TypeName {
	switch t := t.(type) {
	case *types.Alias:
		return t.Obj()
	case *types.Named:
		return t.Obj()
	case *types.TypeParam:
		return t.Obj()
	case *types.Basic:
		// See issues #71886 and #66890 for some history.
		if tname, ok := types.Universe.Lookup(t.Name()).(*types.TypeName); ok {
			return tname
		}
	}
	return nil
}

// A NamedOrAlias is a [types.Type] that is named (as
// defined by the spec) and capable of bearing type parameters: it
// abstracts aliases ([types.Alias]) and defined types
// ([types.Named]).
//
// Every type declared by an explicit "type" declaration is a
// NamedOrAlias. (Built-in type symbols may additionally
// have type [types.Basic], which is not a NamedOrAlias,
// though the spec regards them as "named"; see [TypeNameFor].)
//
// NamedOrAlias cannot expose the Origin method, because
// [types.Alias.Origin] and [types.Named.Origin] have different
// (covariant) result types; use [Origin] instead.
type NamedOrAlias interface {
	types.Type
	Obj() *types.TypeName
	TypeArgs() *types.TypeList
	TypeParams() *types.TypeParamList
	SetTypeParams(tparams []*types.TypeParam)
}

var (
	_ NamedOrAlias = (*types.Alias)(nil)
	_ NamedOrAlias = (*types.Named)(nil)
)

// Origin returns the generic type of the Named or Alias type t if it
// is instantiated, otherwise it returns t.
func Origin(t NamedOrAlias) NamedOrAlias {
	switch t := t.(type) {
	case *types.Alias:
		return t.Origin()
	case *types.Named:
		return t.Origin()
	}
	return t
}

// IsPackageLevel reports whether obj is a package-level symbol.
func IsPackageLevel(obj types.Object) bool {
	return obj.Pkg() != nil && obj.Parent() == obj.Pkg().Scope()
}

// NewTypesInfo returns a *types.Info with all maps populated.
func NewTypesInfo() *types.Info {
	return &types.Info{
		Types:        map[ast.Expr]types.TypeAndValue{},
		Instances:    map[*ast.Ident]types.Instance{},
		Defs:         map[*ast.Ident]types.Object{},
		Uses:         map[*ast.Ident]types.Object{},
		Implicits:    map[ast.Node]types.Object{},
		Selections:   map[*ast.SelectorExpr]*types.Selection{},
		Scopes:       map[ast.Node]*types.Scope{},
		FileVersions: map[*ast.File]string{},
	}
}

// EnclosingScope returns the innermost block logically enclosing the cursor.
func EnclosingScope(info *types.Info, cur inspector.Cursor) *types.Scope {
	for cur := range cur.Enclosing() {
		n := cur.Node()
		// A function's Scope is associated with its FuncType.
		switch f := n.(type) {
		case *ast.FuncDecl:
			n = f.Type
		case *ast.FuncLit:
			n = f.Type
		}
		if b := info.Scopes[n]; b != nil {
			return b
		}
	}
	panic("no Scope for *ast.File")
}

// Imports reports whether path is imported by pkg.
func Imports(pkg *types.Package, path string) bool {
	for _, imp := range pkg.Imports() {
		if imp.Path() == path {
			return true
		}
	}
	return false
}


================================================
FILE: internal/typesinternal/varkind.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build go1.25

package typesinternal

import "go/types"

type VarKind = types.VarKind

const (
	PackageVar = types.PackageVar
	LocalVar   = types.LocalVar
	RecvVar    = types.RecvVar
	ParamVar   = types.ParamVar
	ResultVar  = types.ResultVar
	FieldVar   = types.FieldVar
)

func GetVarKind(v *types.Var) VarKind       { return v.Kind() }
func SetVarKind(v *types.Var, kind VarKind) { v.SetKind(kind) }


================================================
FILE: internal/typesinternal/varkind_go124.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !go1.25

package typesinternal

import "go/types"

type VarKind uint8

const (
	_          VarKind = iota // (not meaningful)
	PackageVar                // a package-level variable
	LocalVar                  // a local variable
	RecvVar                   // a method receiver variable
	ParamVar                  // a function parameter variable
	ResultVar                 // a function result variable
	FieldVar                  // a struct field
)

func (kind VarKind) String() string {
	return [...]string{
		0:          "VarKind(0)",
		PackageVar: "PackageVar",
		LocalVar:   "LocalVar",
		RecvVar:    "RecvVar",
		ParamVar:   "ParamVar",
		ResultVar:  "ResultVar",
		FieldVar:   "FieldVar",
	}[kind]
}

// GetVarKind returns an invalid VarKind.
func GetVarKind(v *types.Var) VarKind { return 0 }

// SetVarKind has no effect.
func SetVarKind(v *types.Var, kind VarKind) {}


================================================
FILE: internal/typesinternal/zerovalue.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"strings"
)

// ZeroString returns the string representation of the zero value for any type t.
// The boolean result indicates whether the type is or contains an invalid type
// or a non-basic (constraint) interface type.
//
// Even for invalid input types, ZeroString may return a partially correct
// string representation. The caller should use the returned isValid boolean
// to determine the validity of the expression.
//
// When assigning to a wider type (such as 'any'), it's the caller's
// responsibility to handle any necessary type conversions.
//
// This string can be used on the right-hand side of an assignment where the
// left-hand side has that explicit type.
// References to named types are qualified by an appropriate (optional)
// qualifier function.
// Exception: This does not apply to tuples. Their string representation is
// informational only and cannot be used in an assignment.
//
// See [ZeroExpr] for a variant that returns an [ast.Expr].
func ZeroString(t types.Type, qual types.Qualifier) (_ string, isValid bool) {
	switch t := t.(type) {
	case *types.Basic:
		switch {
		case t.Info()&types.IsBoolean != 0:
			return "false", true
		case t.Info()&types.IsNumeric != 0:
			return "0", true
		case t.Info()&types.IsString != 0:
			return `""`, true
		case t.Kind() == types.UnsafePointer:
			fallthrough
		case t.Kind() == types.UntypedNil:
			return "nil", true
		case t.Kind() == types.Invalid:
			return "invalid", false
		default:
			panic(fmt.Sprintf("ZeroString for unexpected type %v", t))
		}

	case *types.Pointer, *types.Slice, *types.Chan, *types.Map, *types.Signature:
		return "nil", true

	case *types.Interface:
		if !t.IsMethodSet() {
			return "invalid", false
		}
		return "nil", true

	case *types.Named:
		switch under := t.Underlying().(type) {
		case *types.Struct, *types.Array:
			return types.TypeString(t, qual) + "{}", true
		default:
			return ZeroString(under, qual)
		}

	case *types.Alias:
		switch t.Underlying().(type) {
		case *types.Struct, *types.Array:
			return types.TypeString(t, qual) + "{}", true
		default:
			// A type parameter can have alias but alias type's underlying type
			// can never be a type parameter.
			// Use types.Unalias to preserve the info of type parameter instead
			// of call Underlying() going right through and get the underlying
			// type of the type parameter which is always an interface.
			return ZeroString(types.Unalias(t), qual)
		}

	case *types.Array, *types.Struct:
		return types.TypeString(t, qual) + "{}", true

	case *types.TypeParam:
		// Assumes func new is not shadowed.
		return "*new(" + types.TypeString(t, qual) + ")", true

	case *types.Tuple:
		// Tuples are not normal values.
		// We are currently format as "(t[0], ..., t[n])". Could be something else.
		isValid := true
		components := make([]string, t.Len())
		for i := 0; i < t.Len(); i++ {
			comp, ok := ZeroString(t.At(i).Type(), qual)

			components[i] = comp
			isValid = isValid && ok
		}
		return "(" + strings.Join(components, ", ") + ")", isValid

	case *types.Union:
		// Variables of these types cannot be created, so it makes
		// no sense to ask for their zero value.
		panic(fmt.Sprintf("invalid type for a variable: %v", t))

	default:
		panic(t) // unreachable.
	}
}

// ZeroExpr returns the ast.Expr representation of the zero value for any type t.
// The boolean result indicates whether the type is or contains an invalid type
// or a non-basic (constraint) interface type.
//
// Even for invalid input types, ZeroExpr may return a partially correct ast.Expr
// representation. The caller should use the returned isValid boolean to determine
// the validity of the expression.
//
// This function is designed for types suitable for variables and should not be
// used with Tuple or Union types.References to named types are qualified by an
// appropriate (optional) qualifier function.
//
// See [ZeroString] for a variant that returns a string.
func ZeroExpr(t types.Type, qual types.Qualifier) (_ ast.Expr, isValid bool) {
	switch t := t.(type) {
	case *types.Basic:
		switch {
		case t.Info()&types.IsBoolean != 0:
			return &ast.Ident{Name: "false"}, true
		case t.Info()&types.IsNumeric != 0:
			return &ast.BasicLit{Kind: token.INT, Value: "0"}, true
		case t.Info()&types.IsString != 0:
			return &ast.BasicLit{Kind: token.STRING, Value: `""`}, true
		case t.Kind() == types.UnsafePointer:
			fallthrough
		case t.Kind() == types.UntypedNil:
			return ast.NewIdent("nil"), true
		case t.Kind() == types.Invalid:
			return &ast.BasicLit{Kind: token.STRING, Value: `"invalid"`}, false
		default:
			panic(fmt.Sprintf("ZeroExpr for unexpected type %v", t))
		}

	case *types.Pointer, *types.Slice, *types.Chan, *types.Map, *types.Signature:
		return ast.NewIdent("nil"), true

	case *types.Interface:
		if !t.IsMethodSet() {
			return &ast.BasicLit{Kind: token.STRING, Value: `"invalid"`}, false
		}
		return ast.NewIdent("nil"), true

	case *types.Named:
		switch under := t.Underlying().(type) {
		case *types.Struct, *types.Array:
			return &ast.CompositeLit{
				Type: TypeExpr(t, qual),
			}, true
		default:
			return ZeroExpr(under, qual)
		}

	case *types.Alias:
		switch t.Underlying().(type) {
		case *types.Struct, *types.Array:
			return &ast.CompositeLit{
				Type: TypeExpr(t, qual),
			}, true
		default:
			return ZeroExpr(types.Unalias(t), qual)
		}

	case *types.Array, *types.Struct:
		return &ast.CompositeLit{
			Type: TypeExpr(t, qual),
		}, true

	case *types.TypeParam:
		return &ast.StarExpr{ // *new(T)
			X: &ast.CallExpr{
				// Assumes func new is not shadowed.
				Fun: ast.NewIdent("new"),
				Args: []ast.Expr{
					ast.NewIdent(t.Obj().Name()),
				},
			},
		}, true

	case *types.Tuple:
		// Unlike ZeroString, there is no ast.Expr can express tuple by
		// "(t[0], ..., t[n])".
		panic(fmt.Sprintf("invalid type for a variable: %v", t))

	case *types.Union:
		// Variables of these types cannot be created, so it makes
		// no sense to ask for their zero value.
		panic(fmt.Sprintf("invalid type for a variable: %v", t))

	default:
		panic(t) // unreachable.
	}
}

// TypeExpr returns syntax for the specified type. References to named types
// are qualified by an appropriate (optional) qualifier function.
// It may panic for types such as Tuple or Union.
//
// See also https://go.dev/issues/75604, which will provide a robust
// Type-to-valid-Go-syntax formatter.
func TypeExpr(t types.Type, qual types.Qualifier) ast.Expr {
	switch t := t.(type) {
	case *types.Basic:
		switch t.Kind() {
		case types.UnsafePointer:
			return &ast.SelectorExpr{X: ast.NewIdent(qual(types.NewPackage("unsafe", "unsafe"))), Sel: ast.NewIdent("Pointer")}
		default:
			return ast.NewIdent(t.Name())
		}

	case *types.Pointer:
		return &ast.UnaryExpr{
			Op: token.MUL,
			X:  TypeExpr(t.Elem(), qual),
		}

	case *types.Array:
		return &ast.ArrayType{
			Len: &ast.BasicLit{
				Kind:  token.INT,
				Value: fmt.Sprintf("%d", t.Len()),
			},
			Elt: TypeExpr(t.Elem(), qual),
		}

	case *types.Slice:
		return &ast.ArrayType{
			Elt: TypeExpr(t.Elem(), qual),
		}

	case *types.Map:
		return &ast.MapType{
			Key:   TypeExpr(t.Key(), qual),
			Value: TypeExpr(t.Elem(), qual),
		}

	case *types.Chan:
		dir := ast.ChanDir(t.Dir())
		if t.Dir() == types.SendRecv {
			dir = ast.SEND | ast.RECV
		}
		return &ast.ChanType{
			Dir:   dir,
			Value: TypeExpr(t.Elem(), qual),
		}

	case *types.Signature:
		var params []*ast.Field
		for v := range t.Params().Variables() {
			params = append(params, &ast.Field{
				Type: TypeExpr(v.Type(), qual),
				Names: []*ast.Ident{
					{
						Name: v.Name(),
					},
				},
			})
		}
		if t.Variadic() {
			last := params[len(params)-1]
			last.Type = &ast.Ellipsis{Elt: last.Type.(*ast.ArrayType).Elt}
		}
		var returns []*ast.Field
		for v := range t.Results().Variables() {
			returns = append(returns, &ast.Field{
				Type: TypeExpr(v.Type(), qual),
			})
		}
		return &ast.FuncType{
			Params: &ast.FieldList{
				List: params,
			},
			Results: &ast.FieldList{
				List: returns,
			},
		}

	case *types.TypeParam:
		pkgName := qual(t.Obj().Pkg())
		if pkgName == "" || t.Obj().Pkg() == nil {
			return ast.NewIdent(t.Obj().Name())
		}
		return &ast.SelectorExpr{
			X:   ast.NewIdent(pkgName),
			Sel: ast.NewIdent(t.Obj().Name()),
		}

	// types.TypeParam also implements interface NamedOrAlias. To differentiate,
	// case TypeParam need to be present before case NamedOrAlias.
	// TODO(hxjiang): remove this comment once TypeArgs() is added to interface
	// NamedOrAlias.
	case NamedOrAlias:
		var expr ast.Expr = ast.NewIdent(t.Obj().Name())
		if pkgName := qual(t.Obj().Pkg()); pkgName != "." && pkgName != "" {
			expr = &ast.SelectorExpr{
				X:   ast.NewIdent(pkgName),
				Sel: expr.(*ast.Ident),
			}
		}

		// TODO(hxjiang): call t.TypeArgs after adding method TypeArgs() to
		// typesinternal.NamedOrAlias.
		if hasTypeArgs, ok := t.(interface{ TypeArgs() *types.TypeList }); ok {
			if typeArgs := hasTypeArgs.TypeArgs(); typeArgs != nil && typeArgs.Len() > 0 {
				var indices []ast.Expr
				for t0 := range typeArgs.Types() {
					indices = append(indices, TypeExpr(t0, qual))
				}
				expr = &ast.IndexListExpr{
					X:       expr,
					Indices: indices,
				}
			}
		}

		return expr

	case *types.Struct:
		return ast.NewIdent(t.String())

	case *types.Interface:
		return ast.NewIdent(t.String())

	case *types.Union:
		if t.Len() == 0 {
			panic("Union type should have at least one term")
		}
		// Same as go/ast, the return expression will put last term in the
		// Y field at topmost level of BinaryExpr.
		// For union of type "float32 | float64 | int64", the structure looks
		// similar to:
		// {
		// 	X: {
		// 		X: float32,
		// 		Op: |
		// 		Y: float64,
		// 	}
		// 	Op: |,
		// 	Y: int64,
		// }
		var union ast.Expr
		for i := range t.Len() {
			term := t.Term(i)
			termExpr := TypeExpr(term.Type(), qual)
			if term.Tilde() {
				termExpr = &ast.UnaryExpr{
					Op: token.TILDE,
					X:  termExpr,
				}
			}
			if i == 0 {
				union = termExpr
			} else {
				union = &ast.BinaryExpr{
					X:  union,
					Op: token.OR,
					Y:  termExpr,
				}
			}
		}
		return union

	case *types.Tuple:
		panic("invalid input type types.Tuple")

	default:
		panic("unreachable")
	}
}


================================================
FILE: internal/typesinternal/zerovalue_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package typesinternal_test

import (
	"bytes"
	"go/ast"
	"go/parser"
	"go/printer"
	"go/token"
	"go/types"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/typesinternal"
)

func TestZeroValue(t *testing.T) {
	if testenv.Go1Point() == 23 {
		testenv.NeedsGoExperiment(t, "aliastypeparams")
	}

	// This test only reference types/functions defined within the same package.
	// We can safely drop the package name when encountered.
	qual := types.Qualifier(func(p *types.Package) string {
		return ""
	})
	src := `
package main

type foo struct{
	bar string
}

type aliasFoo = foo

type namedInt int
type namedString string
type namedBool bool
type namedPointer *foo
type namedSlice []foo
type namedInterface interface{ Error() string }
type namedChan chan int
type namedMap map[string]foo
type namedSignature func(string) string
type namedStruct struct{ bar string }
type namedArray [3]foo
type namedAlias aliasFoo

type aliasInt = int
type aliasString = string
type aliasBool = bool
type aliasPointer = *foo
type aliasSlice = []foo
type aliasInterface = interface{ Error() string }
type aliasChan = chan int
type aliasMap = map[string]foo
type aliasSignature = func(string) string
type aliasStruct = struct{ bar string }
type aliasArray = [3]foo
type aliasNamed = foo

func _[T any]() {
	type aliasTypeParam = T

	type aliasWithTypeParam[u any] = struct {
		x u
		y T
	}
	type aliasWithTypeParams[u, q any] = struct {
		x u
		y q
		z T
	}

	type namedWithTypeParam[u any] struct {
		x u
		y T
	}
	type namedWithTypeParams[u, q any] struct{
		x u
		y q
		z T
	}
	var (
		_ int // 0
		_ bool // false
		_ string // ""

		_ *foo // nil
		_ []string // nil
		_ []foo // nil
		_ interface{ Error() string } // nil
		_ chan foo // nil
		_ map[string]foo // nil
		_ func(string) string // nil

		_ namedInt // 0
		_ namedString // ""
		_ namedBool // false
		_ namedSlice // nil
		_ namedInterface // nil
		_ namedChan // nil
		_ namedMap// nil
		_ namedSignature // nil
		_ namedStruct // namedStruct{}
		_ namedArray // namedArray{}
		_ namedAlias // namedAlias{}

		_ aliasInt // 0
		_ aliasString // ""
		_ aliasBool // false
		_ aliasSlice // nil
		_ aliasInterface // nil
		_ aliasChan // nil
		_ aliasMap// nil
		_ aliasSignature // nil
		_ aliasStruct // aliasStruct{}
		_ aliasArray // aliasArray{}
		_ aliasNamed // aliasNamed{}

		_ [4]string // [4]string{}
		_ [5]foo // [5]foo{}
		_ foo // foo{}
		_ struct{f foo} // struct{f foo}{}

		_ T // *new(T)
		_ *T // nil

		_ aliasTypeParam // *new(T)
		_ *aliasTypeParam // nil

		_ aliasWithTypeParam[int] // aliasWithTypeParam[int]{}
		_ aliasWithTypeParams[int, string] // aliasWithTypeParams[int, string]{}

		_ namedWithTypeParam[int] // namedWithTypeParam[int]{}
		_ namedWithTypeParams[int, string] // namedWithTypeParams[int, string]{}
	)
}
`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, parser.ParseComments)
	if err != nil {
		t.Fatalf("parse file error %v on file source:\n%s\n", err, src)
	}
	info := &types.Info{
		Types: make(map[ast.Expr]types.TypeAndValue),
		Defs:  make(map[*ast.Ident]types.Object),
		Uses:  make(map[*ast.Ident]types.Object),
	}
	var conf types.Config
	pkg, err := conf.Check("", fset, []*ast.File{f}, info)
	if err != nil {
		t.Fatalf("type check error %v on file source:\n%s\n", err, src)
	}

	fun, ok := f.Decls[len(f.Decls)-1].(*ast.FuncDecl)
	if !ok {
		t.Fatalf("the last decl of the file is not FuncDecl")
	}

	decl, ok := fun.Body.List[len(fun.Body.List)-1].(*ast.DeclStmt).Decl.(*ast.GenDecl)
	if !ok {
		t.Fatalf("the last statement of the function is not GenDecl")
	}

	for _, spec := range decl.Specs {
		s, ok := spec.(*ast.ValueSpec)
		if !ok {
			t.Fatalf("%s: got %T, want ValueSpec", fset.Position(spec.Pos()), spec)
		}
		want := strings.TrimSpace(s.Comment.Text())

		typ := info.TypeOf(s.Type)
		got, _ := typesinternal.ZeroString(typ, qual)
		if got != want {
			t.Errorf("%s: ZeroString() = %q, want zero value %q", fset.Position(spec.Pos()), got, want)
		}

		zeroExpr, _ := typesinternal.ZeroExpr(typ, typesinternal.FileQualifier(f, pkg))
		var bytes bytes.Buffer
		printer.Fprint(&bytes, fset, zeroExpr)
		got = bytes.String()
		if got != want {
			t.Errorf("%s: ZeroExpr() = %q, want zero value %q", fset.Position(spec.Pos()), got, want)
		}
	}
}


================================================
FILE: internal/versions/features.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package versions

// This file contains predicates for working with file versions to
// decide when a tool should consider a language feature enabled.

// named constants, to avoid misspelling
const (
	Go1_17 = "go1.17"
	Go1_18 = "go1.18"
	Go1_19 = "go1.19"
	Go1_20 = "go1.20"
	Go1_21 = "go1.21"
	Go1_22 = "go1.22"
	Go1_23 = "go1.23"
	Go1_24 = "go1.24"
	Go1_25 = "go1.25"
	Go1_26 = "go1.26"
)

// Future is an invalid unknown Go version sometime in the future.
// Do not use directly with Compare.
const Future = ""

// AtLeast reports whether the file version v comes after a Go release.
//
// Use this predicate to enable a behavior once a certain Go release
// has happened (and stays enabled in the future).
func AtLeast(v, release string) bool {
	if v == Future {
		return true // an unknown future version is always after y.
	}
	return Compare(Lang(v), Lang(release)) >= 0
}

// Before reports whether the file version v is strictly before a Go release.
//
// Use this predicate to disable a behavior once a certain Go release
// has happened (and stays enabled in the future).
func Before(v, release string) bool {
	if v == Future {
		return false // an unknown future version happens after y.
	}
	return Compare(Lang(v), Lang(release)) < 0
}


================================================
FILE: internal/versions/gover.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This is a fork of internal/gover for use by x/tools until
// go1.21 and earlier are no longer supported by x/tools.

package versions

import "strings"

// A gover is a parsed Go gover: major[.Minor[.Patch]][kind[pre]]
// The numbers are the original decimal strings to avoid integer overflows
// and since there is very little actual math. (Probably overflow doesn't matter in practice,
// but at the time this code was written, there was an existing test that used
// go1.99999999999, which does not fit in an int on 32-bit platforms.
// The "big decimal" representation avoids the problem entirely.)
type gover struct {
	major string // decimal
	minor string // decimal or ""
	patch string // decimal or ""
	kind  string // "", "alpha", "beta", "rc"
	pre   string // decimal or ""
}

// compare returns -1, 0, or +1 depending on whether
// x < y, x == y, or x > y, interpreted as toolchain versions.
// The versions x and y must not begin with a "go" prefix: just "1.21" not "go1.21".
// Malformed versions compare less than well-formed versions and equal to each other.
// The language version "1.21" compares less than the release candidate and eventual releases "1.21rc1" and "1.21.0".
func compare(x, y string) int {
	vx := parse(x)
	vy := parse(y)

	if c := cmpInt(vx.major, vy.major); c != 0 {
		return c
	}
	if c := cmpInt(vx.minor, vy.minor); c != 0 {
		return c
	}
	if c := cmpInt(vx.patch, vy.patch); c != 0 {
		return c
	}
	if c := strings.Compare(vx.kind, vy.kind); c != 0 { // "" < alpha < beta < rc
		return c
	}
	if c := cmpInt(vx.pre, vy.pre); c != 0 {
		return c
	}
	return 0
}

// lang returns the Go language version. For example, lang("1.2.3") == "1.2".
func lang(x string) string {
	v := parse(x)
	if v.minor == "" || v.major == "1" && v.minor == "0" {
		return v.major
	}
	return v.major + "." + v.minor
}

// isValid reports whether the version x is valid.
func isValid(x string) bool {
	return parse(x) != gover{}
}

// parse parses the Go version string x into a version.
// It returns the zero version if x is malformed.
func parse(x string) gover {
	var v gover

	// Parse major version.
	var ok bool
	v.major, x, ok = cutInt(x)
	if !ok {
		return gover{}
	}
	if x == "" {
		// Interpret "1" as "1.0.0".
		v.minor = "0"
		v.patch = "0"
		return v
	}

	// Parse . before minor version.
	if x[0] != '.' {
		return gover{}
	}

	// Parse minor version.
	v.minor, x, ok = cutInt(x[1:])
	if !ok {
		return gover{}
	}
	if x == "" {
		// Patch missing is same as "0" for older versions.
		// Starting in Go 1.21, patch missing is different from explicit .0.
		if cmpInt(v.minor, "21") < 0 {
			v.patch = "0"
		}
		return v
	}

	// Parse patch if present.
	if x[0] == '.' {
		v.patch, x, ok = cutInt(x[1:])
		if !ok || x != "" {
			// Note that we are disallowing prereleases (alpha, beta, rc) for patch releases here (x != "").
			// Allowing them would be a bit confusing because we already have:
			//	1.21 < 1.21rc1
			// But a prerelease of a patch would have the opposite effect:
			//	1.21.3rc1 < 1.21.3
			// We've never needed them before, so let's not start now.
			return gover{}
		}
		return v
	}

	// Parse prerelease.
	i := 0
	for i < len(x) && (x[i] < '0' || '9' < x[i]) {
		if x[i] < 'a' || 'z' < x[i] {
			return gover{}
		}
		i++
	}
	if i == 0 {
		return gover{}
	}
	v.kind, x = x[:i], x[i:]
	if x == "" {
		return v
	}
	v.pre, x, ok = cutInt(x)
	if !ok || x != "" {
		return gover{}
	}

	return v
}

// cutInt scans the leading decimal number at the start of x to an integer
// and returns that value and the rest of the string.
func cutInt(x string) (n, rest string, ok bool) {
	i := 0
	for i < len(x) && '0' <= x[i] && x[i] <= '9' {
		i++
	}
	if i == 0 || x[0] == '0' && i != 1 { // no digits or unnecessary leading zero
		return "", "", false
	}
	return x[:i], x[i:], true
}

// cmpInt returns cmp.Compare(x, y) interpreting x and y as decimal numbers.
// (Copied from golang.org/x/mod/semver's compareInt.)
func cmpInt(x, y string) int {
	if x == y {
		return 0
	}
	if len(x) < len(y) {
		return -1
	}
	if len(x) > len(y) {
		return +1
	}
	if x < y {
		return -1
	} else {
		return +1
	}
}


================================================
FILE: internal/versions/types.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package versions

import (
	"go/ast"
	"go/types"
)

// FileVersion returns a file's Go version.
// The reported version is an unknown Future version if a
// version cannot be determined.
func FileVersion(info *types.Info, file *ast.File) string {
	// In tools built with Go >= 1.22, the Go version of a file
	// follow a cascades of sources:
	// 1) types.Info.FileVersion, which follows the cascade:
	//   1.a) file version (ast.File.GoVersion),
	//   1.b) the package version (types.Config.GoVersion), or
	// 2) is some unknown Future version.
	//
	// File versions require a valid package version to be provided to types
	// in Config.GoVersion. Config.GoVersion is either from the package's module
	// or the toolchain (go run). This value should be provided by go/packages
	// or unitchecker.Config.GoVersion.
	if v := info.FileVersions[file]; IsValid(v) {
		return v
	}
	// Note: we could instead return runtime.Version() [if valid].
	// This would act as a max version on what a tool can support.
	return Future
}


================================================
FILE: internal/versions/types_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package versions_test

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"strings"
	"testing"

	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/versions"
)

var contents = map[string]string{
	"gobuild122.go": `
//go:build go1.22
package p
`,
	"gobuild121.go": `
//go:build go1.21
package p
`,
	"gobuild120.go": `
//go:build go1.20
package p
`,
	"gobuild119.go": `
//go:build go1.19
package p
`,
	"noversion.go": `
package p
`,
}

func Test(t *testing.T) {
	testenv.NeedsGo1Point(t, 23) // TODO(#69749): Allow on 1.22 if a fix for #69749 is submitted.

	for _, item := range []struct {
		goversion string
		pversion  string
		tests     []fileTest
	}{
		{
			"", "", []fileTest{
				{"noversion.go", ""},
				{"gobuild119.go", "go1.21"},
				{"gobuild120.go", "go1.21"},
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
		{
			"go1.20", "go1.20", []fileTest{
				{"noversion.go", "go1.20"},
				{"gobuild119.go", "go1.21"},
				{"gobuild120.go", "go1.21"},
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
		{
			"go1.21", "go1.21", []fileTest{
				{"noversion.go", "go1.21"},
				{"gobuild119.go", "go1.21"},
				{"gobuild120.go", "go1.21"},
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
		{
			"go1.22", "go1.22", []fileTest{
				{"noversion.go", "go1.22"},
				{"gobuild119.go", "go1.21"},
				{"gobuild120.go", "go1.21"},
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
	} {
		name := fmt.Sprintf("types.Config{GoVersion:%q}", item.goversion)
		t.Run(name, func(t *testing.T) {
			testFiles(t, item.goversion, item.pversion, item.tests)
		})
	}
}

func TestToolchain122(t *testing.T) {
	// TestToolchain122 tests the 1.22 toolchain for the FileVersion it returns.
	// These results are at the moment unique to 1.22. So test it with distinct
	// expectations.

	// TODO(#69749): Remove requirement if a fix for #69749 is submitted.
	if testenv.Go1Point() != 22 {
		t.Skip("Expectations are only for 1.22 toolchain")
	}

	for _, item := range []struct {
		goversion string
		pversion  string
		tests     []fileTest
	}{
		{
			"", "", []fileTest{
				{"noversion.go", ""},
				{"gobuild119.go", ""},  // differs
				{"gobuild120.go", ""},  // differs
				{"gobuild121.go", ""},  // differs
				{"gobuild122.go", ""}}, // differs
		},
		{
			"go1.20", "go1.20", []fileTest{
				{"noversion.go", "go1.20"},
				{"gobuild119.go", "go1.20"}, // differs
				{"gobuild120.go", "go1.20"}, // differs
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
		{
			"go1.21", "go1.21", []fileTest{
				{"noversion.go", "go1.21"},
				{"gobuild119.go", "go1.19"}, // differs
				{"gobuild120.go", "go1.20"}, // differs
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
		{
			"go1.22", "go1.22", []fileTest{
				{"noversion.go", "go1.22"},
				{"gobuild119.go", "go1.19"}, // differs
				{"gobuild120.go", "go1.20"}, // differs
				{"gobuild121.go", "go1.21"},
				{"gobuild122.go", "go1.22"}},
		},
	} {
		name := fmt.Sprintf("types.Config{GoVersion:%q}", item.goversion)
		t.Run(name, func(t *testing.T) {
			testFiles(t, item.goversion, item.pversion, item.tests)
		})
	}
}

type fileTest struct {
	fname string
	want  string
}

func testFiles(t *testing.T, goversion string, pversion string, tests []fileTest) {

	fset := token.NewFileSet()
	files := make([]*ast.File, len(tests))
	for i, test := range tests {
		files[i] = parse(t, fset, test.fname, contents[test.fname])
	}
	pkg, info, err := typeCheck(fset, files, goversion)
	if err != nil {
		t.Fatal(err)
	}
	if got, want := pkg.GoVersion(), pversion; versions.Compare(got, want) != 0 {
		t.Errorf("GoVersion()=%q. expected %q", got, want)
	}
	if got := versions.FileVersion(info, nil); got != "" {
		t.Errorf(`FileVersions(nil)=%q. expected ""`, got)
	}
	for i, test := range tests {
		if got, want := versions.FileVersion(info, files[i]), test.want; got != want {
			t.Errorf("FileVersions(%s)=%q. expected %q", test.fname, got, want)
		}
	}
}

func TestTooNew(t *testing.T) {
	testenv.NeedsGo1Point(t, 23) // TODO(#69749): Allow on 1.22 if a fix for #69749 is submitted.

	const contents = `
	//go:build go1.99
	package p
	`

	for _, goversion := range []string{
		"",
		"go1.22",
	} {
		name := fmt.Sprintf("types.Config{GoVersion:%q}", goversion)
		t.Run(name, func(t *testing.T) {
			fset := token.NewFileSet()
			files := []*ast.File{parse(t, fset, "p.go", contents)}
			_, _, err := typeCheck(fset, files, goversion)
			if err == nil {
				t.Fatal("Expected an error from a using a TooNew file version")
			}
			got := err.Error()
			want := "file requires newer Go version go1.99"
			if !strings.Contains(got, want) {
				t.Errorf("Error message %q did not include %q", got, want)
			}
		})
	}
}

func parse(t *testing.T, fset *token.FileSet, name, src string) *ast.File {
	file, err := parser.ParseFile(fset, name, src, 0)
	if err != nil {
		t.Fatal(err)
	}
	return file
}

func typeCheck(fset *token.FileSet, files []*ast.File, goversion string) (*types.Package, *types.Info, error) {
	conf := types.Config{
		Importer:  importer.Default(),
		GoVersion: goversion,
	}
	info := types.Info{
		FileVersions: make(map[*ast.File]string),
	}
	pkg, err := conf.Check("", fset, files, &info)
	return pkg, &info, err
}


================================================
FILE: internal/versions/versions.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package versions

import (
	"strings"
)

// Note: If we use build tags to use go/versions when go >=1.22,
// we run into go.dev/issue/53737. Under some operations users would see an
// import of "go/versions" even if they would not compile the file.
// For example, during `go get -u ./...` (go.dev/issue/64490) we do not try to include
// For this reason, this library just a clone of go/versions for the moment.

// Lang returns the Go language version for version x.
// If x is not a valid version, Lang returns the empty string.
// For example:
//
//	Lang("go1.21rc2") = "go1.21"
//	Lang("go1.21.2") = "go1.21"
//	Lang("go1.21") = "go1.21"
//	Lang("go1") = "go1"
//	Lang("bad") = ""
//	Lang("1.21") = ""
func Lang(x string) string {
	v := lang(stripGo(x))
	if v == "" {
		return ""
	}
	return x[:2+len(v)] // "go"+v without allocation
}

// Compare returns -1, 0, or +1 depending on whether
// x < y, x == y, or x > y, interpreted as Go versions.
// The versions x and y must begin with a "go" prefix: "go1.21" not "1.21".
// Invalid versions, including the empty string, compare less than
// valid versions and equal to each other.
// The language version "go1.21" compares less than the
// release candidate and eventual releases "go1.21rc1" and "go1.21.0".
// Custom toolchain suffixes are ignored during comparison:
// "go1.21.0" and "go1.21.0-bigcorp" are equal.
func Compare(x, y string) int { return compare(stripGo(x), stripGo(y)) }

// IsValid reports whether the version x is valid.
func IsValid(x string) bool { return isValid(stripGo(x)) }

// stripGo converts from a "go1.21" version to a "1.21" version.
// If v does not start with "go", stripGo returns the empty string (a known invalid version).
func stripGo(v string) string {
	v, _, _ = strings.Cut(v, "-") // strip -bigcorp suffix.
	if len(v) < 2 || v[:2] != "go" {
		return ""
	}
	return v[2:]
}


================================================
FILE: internal/versions/versions_test.go
================================================
// Copyright 2023 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package versions_test

import (
	"go/ast"
	"go/parser"
	"go/token"
	"go/types"
	"testing"

	"golang.org/x/tools/internal/versions"
)

func TestIsValid(t *testing.T) {
	// valid versions
	for _, x := range []string{
		"go1.21",
		"go1.21.2",
		"go1.21rc",
		"go1.21rc2",
		"go0.0", // ??
		"go1",
		"go2",
		"go1.20.0-bigcorp",
	} {
		if !versions.IsValid(x) {
			t.Errorf("expected versions.IsValid(%q) to hold", x)
		}
	}

	// invalid versions
	for _, x := range []string{
		"",
		"bad",
		"1.21",
		"v1.21",
		"go",
		"goAA",
		"go2_3",
		"go1.BB",
		"go1.21.",
		"go1.21.2_2",
		"go1.21rc_2",
		"go1.21rc2_",
		"go1.600+auto",
	} {
		if versions.IsValid(x) {
			t.Errorf("expected versions.IsValid(%q) to not hold", x)
		}
	}
}

func TestVersionComparisons(t *testing.T) {
	for _, item := range []struct {
		x, y string
		want int
	}{
		// All comparisons of go2, go1.21.2, go1.21rc2, go1.21rc, go1, go0.0, "", bad
		{"go2", "go2", 0},
		{"go2", "go1.21.2", +1},
		{"go2", "go1.21rc2", +1},
		{"go2", "go1.21rc", +1},
		{"go2", "go1.21", +1},
		{"go2", "go1", +1},
		{"go2", "go0.0", +1},
		{"go2", "", +1},
		{"go2", "bad", +1},
		{"go1.21.2", "go1.21.2", 0},
		{"go1.21.2", "go1.21rc2", +1},
		{"go1.21.2", "go1.21rc", +1},
		{"go1.21.2", "go1.21", +1},
		{"go1.21.2", "go1", +1},
		{"go1.21.2", "go0.0", +1},
		{"go1.21.2", "", +1},
		{"go1.21.2", "bad", +1},
		{"go1.21rc2", "go1.21rc2", 0},
		{"go1.21rc2", "go1.21rc", +1},
		{"go1.21rc2", "go1.21", +1},
		{"go1.21rc2", "go1", +1},
		{"go1.21rc2", "go0.0", +1},
		{"go1.21rc2", "", +1},
		{"go1.21rc2", "bad", +1},
		{"go1.21rc", "go1.21rc", 0},
		{"go1.21rc", "go1.21", +1},
		{"go1.21rc", "go1", +1},
		{"go1.21rc", "go0.0", +1},
		{"go1.21rc", "", +1},
		{"go1.21rc", "bad", +1},
		{"go1.21", "go1.21", 0},
		{"go1.21", "go1", +1},
		{"go1.21", "go0.0", +1},
		{"go1.21", "", +1},
		{"go1.21", "bad", +1},
		{"go1", "go1", 0},
		{"go1", "go0.0", +1},
		{"go1", "", +1},
		{"go1", "bad", +1},
		{"go0.0", "go0.0", 0},
		{"go0.0", "", +1},
		{"go0.0", "bad", +1},
		{"", "", 0},
		{"", "bad", 0},
		{"bad", "bad", 0},
		// Other tests.
		{"go1.20", "go1.20.0-bigcorp", 0},
		{"go1.21", "go1.21.0-bigcorp", -1},  // Starting in Go 1.21, patch missing is different from explicit .0.
		{"go1.21.0", "go1.21.0-bigcorp", 0}, // Starting in Go 1.21, patch missing is different from explicit .0.
		{"go1.19rc1", "go1.19", -1},
	} {
		got := versions.Compare(item.x, item.y)
		if got != item.want {
			t.Errorf("versions.Compare(%q, %q)=%d. expected %d", item.x, item.y, got, item.want)
		}
		reverse := versions.Compare(item.y, item.x)
		if reverse != -got {
			t.Errorf("versions.Compare(%q, %q)=%d. expected %d", item.y, item.x, reverse, -got)
		}
	}
}

func TestLang(t *testing.T) {
	for _, item := range []struct {
		x    string
		want string
	}{
		// valid
		{"go1.21rc2", "go1.21"},
		{"go1.21.2", "go1.21"},
		{"go1.21", "go1.21"},
		{"go1", "go1"},
		// invalid
		{"bad", ""},
		{"1.21", ""},
	} {
		if got := versions.Lang(item.x); got != item.want {
			t.Errorf("versions.Lang(%q)=%q. expected %q", item.x, got, item.want)
		}
	}

}

func TestKnown(t *testing.T) {
	for _, v := range [...]string{
		versions.Go1_18,
		versions.Go1_19,
		versions.Go1_20,
		versions.Go1_21,
		versions.Go1_22,
	} {
		if !versions.IsValid(v) {
			t.Errorf("Expected known version %q to be valid.", v)
		}
		if v != versions.Lang(v) {
			t.Errorf("Expected known version %q == Lang(%q).", v, versions.Lang(v))
		}
	}
}

func TestAtLeast(t *testing.T) {
	for _, item := range [...]struct {
		v, release string
		want       bool
	}{
		{versions.Future, versions.Go1_22, true},
		{versions.Go1_22, versions.Go1_22, true},
		{"go1.21", versions.Go1_22, false},
		{"invalid", versions.Go1_22, false},
	} {
		if got := versions.AtLeast(item.v, item.release); got != item.want {
			t.Errorf("AtLeast(%q, %q)=%v. wanted %v", item.v, item.release, got, item.want)
		}
	}
}

func TestBefore(t *testing.T) {
	for _, item := range [...]struct {
		v, release string
		want       bool
	}{
		{versions.Future, versions.Go1_22, false},
		{versions.Go1_22, versions.Go1_22, false},
		{"go1.21", versions.Go1_22, true},
		{"invalid", versions.Go1_22, true}, // invalid < Go1_22
	} {
		if got := versions.Before(item.v, item.release); got != item.want {
			t.Errorf("Before(%q, %q)=%v. wanted %v", item.v, item.release, got, item.want)
		}
	}
}

func TestFileVersions(t *testing.T) {
	const source = `
	package P
	`
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "hello.go", source, 0)
	if err != nil {
		t.Fatal(err)
	}

	for _, conf := range []types.Config{
		{GoVersion: versions.Go1_22},
		{}, // GoVersion is unset.
	} {
		info := &types.Info{
			FileVersions: make(map[*ast.File]string),
		}

		_, err = conf.Check("P", fset, []*ast.File{f}, info)
		if err != nil {
			t.Fatal(err)
		}

		v := versions.FileVersion(info, f)
		if !versions.AtLeast(v, versions.Go1_22) {
			t.Errorf("versions.AtLeast(%q, %q) expected to hold", v, versions.Go1_22)
		}

		if versions.Before(v, versions.Go1_22) {
			t.Errorf("versions.AtLeast(%q, %q) expected to be false", v, versions.Go1_22)
		}

		if conf.GoVersion == "" && v != versions.Future {
			t.Error("Expected the FileVersion to be the Future when conf.GoVersion is unset")
		}
	}
}


================================================
FILE: internal/xcontext/xcontext.go
================================================
// Copyright 2019 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package xcontext is a package to offer the extra functionality we need
// from contexts that is not available from the standard context package.
package xcontext

import (
	"context"
	"time"
)

// Detach returns a context that keeps all the values of its parent context
// but detaches from the cancellation and error handling.
func Detach(ctx context.Context) context.Context { return detachedContext{ctx} }

type detachedContext struct{ parent context.Context }

func (v detachedContext) Deadline() (time.Time, bool) { return time.Time{}, false }
func (v detachedContext) Done() <-chan struct{}       { return nil }
func (v detachedContext) Err() error                  { return nil }
func (v detachedContext) Value(key any) any           { return v.parent.Value(key) }


================================================
FILE: playground/playground.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package playground registers an HTTP handler at "/compile" that
// proxies requests to the golang.org playground service.
// This package may be used unaltered on App Engine Standard with Go 1.11+ runtime.
package playground // import "golang.org/x/tools/playground"

import (
	"bytes"
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"time"
)

const baseURL = "https://play.golang.org"

func init() {
	http.Handle("/compile", Proxy())
}

// Proxy returns a handler that can be registered on /compile to proxy requests to the Go playground.
//
// This package already contains a func init that does:
//
//	func init() {
//		http.Handle("/compile", Proxy())
//	}
//
// Proxy may be useful for servers that use HTTP muxes other than the default mux.
func Proxy() http.Handler {
	return http.HandlerFunc(bounce)
}

func bounce(w http.ResponseWriter, r *http.Request) {
	b := new(bytes.Buffer)
	if err := passThru(b, r); err != nil {
		http.Error(w, "500 Internal Server Error", http.StatusInternalServerError)
		log.Println(err)
		return
	}
	io.Copy(w, b)
}

func passThru(w io.Writer, req *http.Request) error {
	defer req.Body.Close()
	url := baseURL + req.URL.Path
	ctx, cancel := context.WithTimeout(req.Context(), 60*time.Second)
	defer cancel()
	r, err := post(ctx, url, req.Header.Get("Content-Type"), req.Body)
	if err != nil {
		return fmt.Errorf("making POST request: %v", err)
	}
	defer r.Body.Close()
	if _, err := io.Copy(w, r.Body); err != nil {
		return fmt.Errorf("copying response Body: %v", err)
	}
	return nil
}

func post(ctx context.Context, url, contentType string, body io.Reader) (*http.Response, error) {
	req, err := http.NewRequest(http.MethodPost, url, body)
	if err != nil {
		return nil, fmt.Errorf("http.NewRequest: %v", err)
	}
	req.Header.Set("Content-Type", contentType)
	return http.DefaultClient.Do(req.WithContext(ctx))
}


================================================
FILE: playground/socket/socket.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

//go:build !appengine

// Package socket implements a WebSocket-based playground backend.
// Clients connect to a websocket handler and send run/kill commands, and
// the server sends the output and exit status of the running processes.
// Multiple clients running multiple processes may be served concurrently.
// The wire format is JSON and is described by the Message type.
//
// This will not run on App Engine as WebSockets are not supported there.
package socket // import "golang.org/x/tools/playground/socket"

import (
	"bytes"
	"encoding/json"
	"errors"
	"go/parser"
	"go/token"
	"io"
	"log"
	"net"
	"net/http"
	"net/url"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"slices"
	"strings"
	"time"
	"unicode/utf8"

	"golang.org/x/net/websocket"
	"golang.org/x/tools/txtar"
)

// RunScripts specifies whether the socket handler should execute shell scripts
// (snippets that start with a shebang).
var RunScripts = true

// Environ provides an environment when a binary, such as the go tool, is
// invoked.
var Environ func() []string = os.Environ

const (
	// The maximum number of messages to send per session (avoid flooding).
	msgLimit = 1000

	// Batch messages sent in this interval and send as a single message.
	msgDelay = 10 * time.Millisecond
)

// Message is the wire format for the websocket connection to the browser.
// It is used for both sending output messages and receiving commands, as
// distinguished by the Kind field.
type Message struct {
	Id      string // client-provided unique id for the process
	Kind    string // in: "run", "kill" out: "stdout", "stderr", "end"
	Body    string
	Options *Options `json:",omitempty"`
}

// Options specify additional message options.
type Options struct {
	Race bool // use -race flag when building code (for "run" only)
}

// NewHandler returns a websocket server which checks the origin of requests.
func NewHandler(origin *url.URL) websocket.Server {
	return websocket.Server{
		Config:    websocket.Config{Origin: origin},
		Handshake: handshake,
		Handler:   websocket.Handler(socketHandler),
	}
}

// handshake checks the origin of a request during the websocket handshake.
func handshake(c *websocket.Config, req *http.Request) error {
	o, err := websocket.Origin(c, req)
	if err != nil {
		log.Println("bad websocket origin:", err)
		return websocket.ErrBadWebSocketOrigin
	}
	_, port, err := net.SplitHostPort(c.Origin.Host)
	if err != nil {
		log.Println("bad websocket origin:", err)
		return websocket.ErrBadWebSocketOrigin
	}
	ok := c.Origin.Scheme == o.Scheme && (c.Origin.Host == o.Host || c.Origin.Host == net.JoinHostPort(o.Host, port))
	if !ok {
		log.Println("bad websocket origin:", o)
		return websocket.ErrBadWebSocketOrigin
	}
	log.Println("accepting connection from:", req.RemoteAddr)
	return nil
}

// socketHandler handles the websocket connection for a given present session.
// It handles transcoding Messages to and from JSON format, and starting
// and killing processes.
func socketHandler(c *websocket.Conn) {
	in, out := make(chan *Message), make(chan *Message)
	errc := make(chan error, 1)

	// Decode messages from client and send to the in channel.
	go func() {
		dec := json.NewDecoder(c)
		for {
			var m Message
			if err := dec.Decode(&m); err != nil {
				errc <- err
				return
			}
			in <- &m
		}
	}()

	// Receive messages from the out channel and encode to the client.
	go func() {
		enc := json.NewEncoder(c)
		for m := range out {
			if err := enc.Encode(m); err != nil {
				errc <- err
				return
			}
		}
	}()
	defer close(out)

	// Start and kill processes and handle errors.
	proc := make(map[string]*process)
	for {
		select {
		case m := <-in:
			switch m.Kind {
			case "run":
				log.Println("running snippet from:", c.Request().RemoteAddr)
				proc[m.Id].Kill()
				proc[m.Id] = startProcess(m.Id, m.Body, out, m.Options)
			case "kill":
				proc[m.Id].Kill()
			}
		case err := <-errc:
			if err != io.EOF {
				// A encode or decode has failed; bail.
				log.Println(err)
			}
			// Shut down any running processes.
			for _, p := range proc {
				p.Kill()
			}
			return
		}
	}
}

// process represents a running process.
type process struct {
	out  chan<- *Message
	done chan struct{} // closed when wait completes
	run  *exec.Cmd
	path string
}

// startProcess builds and runs the given program, sending its output
// and end event as Messages on the provided channel.
func startProcess(id, body string, dest chan<- *Message, opt *Options) *process {
	var (
		done = make(chan struct{})
		out  = make(chan *Message)
		p    = &process{out: out, done: done}
	)
	go func() {
		defer close(done)
		for m := range buffer(limiter(out, p), time.After) {
			m.Id = id
			dest <- m
		}
	}()
	var err error
	if path, args := shebang(body); path != "" {
		if RunScripts {
			err = p.startProcess(path, args, body)
		} else {
			err = errors.New("script execution is not allowed")
		}
	} else {
		err = p.start(body, opt)
	}
	if err != nil {
		p.end(err)
		return nil
	}
	go func() {
		p.end(p.run.Wait())
	}()
	return p
}

// end sends an "end" message to the client, containing the process id and the
// given error value. It also removes the binary, if present.
func (p *process) end(err error) {
	if p.path != "" {
		defer os.RemoveAll(p.path)
	}
	m := &Message{Kind: "end"}
	if err != nil {
		m.Body = err.Error()
	}
	p.out <- m
	close(p.out)
}

// A killer provides a mechanism to terminate a process.
// The Kill method returns only once the process has exited.
type killer interface {
	Kill()
}

// limiter returns a channel that wraps the given channel.
// It receives Messages from the given channel and sends them to the returned
// channel until it passes msgLimit messages, at which point it will kill the
// process and pass only the "end" message.
// When the given channel is closed, or when the "end" message is received,
// it closes the returned channel.
func limiter(in <-chan *Message, p killer) <-chan *Message {
	out := make(chan *Message)
	go func() {
		defer close(out)
		n := 0
		for m := range in {
			switch {
			case n < msgLimit || m.Kind == "end":
				out <- m
				if m.Kind == "end" {
					return
				}
			case n == msgLimit:
				// Kill in a goroutine as Kill will not return
				// until the process' output has been
				// processed, and we're doing that in this loop.
				go p.Kill()
			default:
				continue // don't increment
			}
			n++
		}
	}()
	return out
}

// buffer returns a channel that wraps the given channel. It receives messages
// from the given channel and sends them to the returned channel.
// Message bodies are gathered over the period msgDelay and coalesced into a
// single Message before they are passed on. Messages of the same kind are
// coalesced; when a message of a different kind is received, any buffered
// messages are flushed. When the given channel is closed, buffer flushes the
// remaining buffered messages and closes the returned channel.
// The timeAfter func should be time.After. It exists for testing.
func buffer(in <-chan *Message, timeAfter func(time.Duration) <-chan time.Time) <-chan *Message {
	out := make(chan *Message)
	go func() {
		defer close(out)
		var (
			tc    <-chan time.Time
			buf   []byte
			kind  string
			flush = func() {
				if len(buf) == 0 {
					return
				}
				out <- &Message{Kind: kind, Body: safeString(buf)}
				buf = buf[:0] // recycle buffer
				kind = ""
			}
		)
		for {
			select {
			case m, ok := <-in:
				if !ok {
					flush()
					return
				}
				if m.Kind == "end" {
					flush()
					out <- m
					return
				}
				if kind != m.Kind {
					flush()
					kind = m.Kind
					if tc == nil {
						tc = timeAfter(msgDelay)
					}
				}
				buf = append(buf, m.Body...)
			case <-tc:
				flush()
				tc = nil
			}
		}
	}()
	return out
}

// Kill stops the process if it is running and waits for it to exit.
func (p *process) Kill() {
	if p == nil || p.run == nil {
		return
	}
	p.run.Process.Kill()
	<-p.done // block until process exits
}

// shebang looks for a shebang ('#!') at the beginning of the passed string.
// If found, it returns the path and args after the shebang.
// args includes the command as args[0].
func shebang(body string) (path string, args []string) {
	body = strings.TrimSpace(body)
	if !strings.HasPrefix(body, "#!") {
		return "", nil
	}
	if i := strings.Index(body, "\n"); i >= 0 {
		body = body[:i]
	}
	fs := strings.Fields(body[2:])
	return fs[0], fs
}

// startProcess starts a given program given its path and passing the given body
// to the command standard input.
func (p *process) startProcess(path string, args []string, body string) error {
	cmd := &exec.Cmd{
		Path:   path,
		Args:   args,
		Stdin:  strings.NewReader(body),
		Stdout: &messageWriter{kind: "stdout", out: p.out},
		Stderr: &messageWriter{kind: "stderr", out: p.out},
	}
	if err := cmd.Start(); err != nil {
		return err
	}
	p.run = cmd
	return nil
}

// start builds and starts the given program, sending its output to p.out,
// and stores the running *exec.Cmd in the run field.
func (p *process) start(body string, opt *Options) error {
	// We "go build" and then exec the binary so that the
	// resultant *exec.Cmd is a handle to the user's program
	// (rather than the go tool process).
	// This makes Kill work.

	path, err := os.MkdirTemp("", "present-")
	if err != nil {
		return err
	}
	p.path = path // to be removed by p.end

	out := "prog"
	if runtime.GOOS == "windows" {
		out = "prog.exe"
	}
	bin := filepath.Join(path, out)

	// write body to x.go files
	a := txtar.Parse([]byte(body))
	if len(a.Comment) != 0 {
		a.Files = append(a.Files, txtar.File{Name: "prog.go", Data: a.Comment})
		a.Comment = nil
	}
	hasModfile := false
	for _, f := range a.Files {
		err = os.WriteFile(filepath.Join(path, f.Name), f.Data, 0666)
		if err != nil {
			return err
		}
		if f.Name == "go.mod" {
			hasModfile = true
		}
	}

	// build x.go, creating x
	args := []string{"go", "build", "-tags", "OMIT"}
	if opt != nil && opt.Race {
		p.out <- &Message{
			Kind: "stderr",
			Body: "Running with race detector.\n",
		}
		args = append(args, "-race")
	}
	args = append(args, "-o", bin)
	cmd := p.cmd(path, args...)
	if !hasModfile {
		cmd.Env = append(cmd.Env, "GO111MODULE=off")
	}
	cmd.Stdout = cmd.Stderr // send compiler output to stderr
	if err := cmd.Run(); err != nil {
		return err
	}

	// run x
	if isNacl() {
		cmd, err = p.naclCmd(bin)
		if err != nil {
			return err
		}
	} else {
		cmd = p.cmd("", bin)
	}
	if opt != nil && opt.Race {
		cmd.Env = append(cmd.Env, "GOMAXPROCS=2")
	}
	if err := cmd.Start(); err != nil {
		// If we failed to exec, that might be because they built
		// a non-main package instead of an executable.
		// Check and report that.
		if name, err := packageName(body); err == nil && name != "main" {
			return errors.New(`executable programs must use "package main"`)
		}
		return err
	}
	p.run = cmd
	return nil
}

// cmd builds an *exec.Cmd that writes its standard output and error to the
// process' output channel.
func (p *process) cmd(dir string, args ...string) *exec.Cmd {
	cmd := exec.Command(args[0], args[1:]...)
	cmd.Dir = dir
	cmd.Env = Environ()
	cmd.Stdout = &messageWriter{kind: "stdout", out: p.out}
	cmd.Stderr = &messageWriter{kind: "stderr", out: p.out}
	return cmd
}

func isNacl() bool {
	return slices.Contains(append(Environ(), os.Environ()...), "GOOS=nacl")
}

// naclCmd returns an *exec.Cmd that executes bin under native client.
func (p *process) naclCmd(bin string) (*exec.Cmd, error) {
	pwd, err := os.Getwd()
	if err != nil {
		return nil, err
	}
	var args []string
	env := []string{
		"NACLENV_GOOS=" + runtime.GOOS,
		"NACLENV_GOROOT=/go",
		"NACLENV_NACLPWD=" + strings.Replace(pwd, runtime.GOROOT(), "/go", 1),
	}
	switch runtime.GOARCH {
	case "amd64":
		env = append(env, "NACLENV_GOARCH=amd64p32")
		args = []string{"sel_ldr_x86_64"}
	case "386":
		env = append(env, "NACLENV_GOARCH=386")
		args = []string{"sel_ldr_x86_32"}
	case "arm":
		env = append(env, "NACLENV_GOARCH=arm")
		selLdr, err := exec.LookPath("sel_ldr_arm")
		if err != nil {
			return nil, err
		}
		args = []string{"nacl_helper_bootstrap_arm", selLdr, "--reserved_at_zero=0xXXXXXXXXXXXXXXXX"}
	default:
		return nil, errors.New("native client does not support GOARCH=" + runtime.GOARCH)
	}

	cmd := p.cmd("", append(args, "-l", "/dev/null", "-S", "-e", bin)...)
	cmd.Env = append(cmd.Env, env...)

	return cmd, nil
}

func packageName(body string) (string, error) {
	f, err := parser.ParseFile(token.NewFileSet(), "prog.go",
		strings.NewReader(body), parser.PackageClauseOnly)
	if err != nil {
		return "", err
	}
	return f.Name.String(), nil
}

// messageWriter is an io.Writer that converts all writes to Message sends on
// the out channel with the specified id and kind.
type messageWriter struct {
	kind string
	out  chan<- *Message
}

func (w *messageWriter) Write(b []byte) (n int, err error) {
	w.out <- &Message{Kind: w.kind, Body: safeString(b)}
	return len(b), nil
}

// safeString returns b as a valid UTF-8 string.
func safeString(b []byte) string {
	if utf8.Valid(b) {
		return string(b)
	}
	var buf bytes.Buffer
	for len(b) > 0 {
		r, size := utf8.DecodeRune(b)
		b = b[size:]
		buf.WriteRune(r)
	}
	return buf.String()
}


================================================
FILE: playground/socket/socket_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package socket

import (
	"testing"
	"time"
)

func TestBuffer(t *testing.T) {
	afterChan := make(chan time.Time)
	ch := make(chan *Message)
	go func() {
		ch <- &Message{Kind: "err", Body: "a"}
		ch <- &Message{Kind: "err", Body: "b"}
		ch <- &Message{Kind: "out", Body: "1"}
		ch <- &Message{Kind: "out", Body: "2"}
		afterChan <- time.Time{} // value itself doesn't matter
		ch <- &Message{Kind: "out", Body: "3"}
		ch <- &Message{Kind: "out", Body: "4"}
		close(ch)
	}()

	var ms []*Message
	timeAfter := func(d time.Duration) <-chan time.Time {
		return afterChan
	}
	for m := range buffer(ch, timeAfter) {
		ms = append(ms, m)
	}
	if len(ms) != 3 {
		t.Fatalf("got %v messages, want 3", len(ms))
	}
	if g, w := ms[0].Body, "ab"; g != w {
		t.Errorf("message 0 body = %q, want %q", g, w)
	}
	if g, w := ms[1].Body, "12"; g != w {
		t.Errorf("message 1 body = %q, want %q", g, w)
	}
	if g, w := ms[2].Body, "34"; g != w {
		t.Errorf("message 2 body = %q, want %q", g, w)
	}
}

type killRecorder chan struct{}

func (k killRecorder) Kill() { close(k) }

func TestLimiter(t *testing.T) {
	ch := make(chan *Message)
	go func() {
		var m Message
		for range msgLimit + 10 {
			ch <- &m
		}
		ch <- &Message{Kind: "end"}
	}()

	kr := make(killRecorder)
	n := 0
	for m := range limiter(ch, kr) {
		n++
		if n > msgLimit && m.Kind != "end" {
			t.Errorf("received non-end message after limit")
		}
	}
	if n != msgLimit+1 {
		t.Errorf("received %v messages, want %v", n, msgLimit+1)
	}
	<-kr
}


================================================
FILE: present/args.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"errors"
	"regexp"
	"strconv"
	"unicode/utf8"
)

// This file is stolen from go/src/cmd/godoc/codewalk.go.
// It's an evaluator for the file address syntax implemented by acme and sam,
// but using Go-native regular expressions.
// To keep things reasonably close, this version uses (?m:re) for all user-provided
// regular expressions. That is the only change to the code from codewalk.go.
// See http://9p.io/sys/doc/sam/sam.html Table II for details on the syntax.

// addrToByteRange evaluates the given address starting at offset start in data.
// It returns the lo and hi byte offset of the matched region within data.
func addrToByteRange(addr string, start int, data []byte) (lo, hi int, err error) {
	if addr == "" {
		lo, hi = start, len(data)
		return
	}
	var (
		dir        byte
		prevc      byte
		charOffset bool
	)
	lo = start
	hi = start
	for addr != "" && err == nil {
		c := addr[0]
		switch c {
		default:
			err = errors.New("invalid address syntax near " + string(c))
		case ',':
			if len(addr) == 1 {
				hi = len(data)
			} else {
				_, hi, err = addrToByteRange(addr[1:], hi, data)
			}
			return

		case '+', '-':
			if prevc == '+' || prevc == '-' {
				lo, hi, err = addrNumber(data, lo, hi, prevc, 1, charOffset)
			}
			dir = c

		case '$':
			lo = len(data)
			hi = len(data)
			if len(addr) > 1 {
				dir = '+'
			}

		case '#':
			charOffset = true

		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			var i int
			for i = 1; i < len(addr); i++ {
				if addr[i] < '0' || addr[i] > '9' {
					break
				}
			}
			var n int
			n, err = strconv.Atoi(addr[0:i])
			if err != nil {
				break
			}
			lo, hi, err = addrNumber(data, lo, hi, dir, n, charOffset)
			dir = 0
			charOffset = false
			prevc = c
			addr = addr[i:]
			continue

		case '/':
			var i, j int
		Regexp:
			for i = 1; i < len(addr); i++ {
				switch addr[i] {
				case '\\':
					i++
				case '/':
					j = i + 1
					break Regexp
				}
			}
			if j == 0 {
				j = i
			}
			pattern := addr[1:i]
			lo, hi, err = addrRegexp(data, hi, dir, pattern)
			prevc = c
			addr = addr[j:]
			continue
		}
		prevc = c
		addr = addr[1:]
	}

	if err == nil && dir != 0 {
		lo, hi, err = addrNumber(data, lo, hi, dir, 1, charOffset)
	}
	if err != nil {
		return 0, 0, err
	}
	return lo, hi, nil
}

// addrNumber applies the given dir, n, and charOffset to the address lo, hi.
// dir is '+' or '-', n is the count, and charOffset is true if the syntax
// used was #n.  Applying +n (or +#n) means to advance n lines
// (or characters) after hi.  Applying -n (or -#n) means to back up n lines
// (or characters) before lo.
// The return value is the new lo, hi.
func addrNumber(data []byte, lo, hi int, dir byte, n int, charOffset bool) (int, int, error) {
	switch dir {
	case 0:
		lo = 0
		hi = 0
		fallthrough

	case '+':
		if charOffset {
			pos := hi
			for ; n > 0 && pos < len(data); n-- {
				_, size := utf8.DecodeRune(data[pos:])
				pos += size
			}
			if n == 0 {
				return pos, pos, nil
			}
			break
		}
		// find next beginning of line
		if hi > 0 {
			for hi < len(data) && data[hi-1] != '\n' {
				hi++
			}
		}
		lo = hi
		if n == 0 {
			return lo, hi, nil
		}
		for ; hi < len(data); hi++ {
			if data[hi] != '\n' {
				continue
			}
			switch n--; n {
			case 1:
				lo = hi + 1
			case 0:
				return lo, hi + 1, nil
			}
		}

	case '-':
		if charOffset {
			// Scan backward for bytes that are not UTF-8 continuation bytes.
			pos := lo
			for ; pos > 0 && n > 0; pos-- {
				if data[pos]&0xc0 != 0x80 {
					n--
				}
			}
			if n == 0 {
				return pos, pos, nil
			}
			break
		}
		// find earlier beginning of line
		for lo > 0 && data[lo-1] != '\n' {
			lo--
		}
		hi = lo
		if n == 0 {
			return lo, hi, nil
		}
		for ; lo >= 0; lo-- {
			if lo > 0 && data[lo-1] != '\n' {
				continue
			}
			switch n--; n {
			case 1:
				hi = lo
			case 0:
				return lo, hi, nil
			}
		}
	}

	return 0, 0, errors.New("address out of range")
}

// addrRegexp searches for pattern in the given direction starting at lo, hi.
// The direction dir is '+' (search forward from hi) or '-' (search backward from lo).
// Backward searches are unimplemented.
func addrRegexp(data []byte, hi int, dir byte, pattern string) (int, int, error) {
	// We want ^ and $ to work as in sam/acme, so use ?m.
	re, err := regexp.Compile("(?m:" + pattern + ")")
	if err != nil {
		return 0, 0, err
	}
	if dir == '-' {
		// Could implement reverse search using binary search
		// through file, but that seems like overkill.
		return 0, 0, errors.New("reverse search not implemented")
	}
	m := re.FindIndex(data[hi:])
	if len(m) > 0 {
		m[0] += hi
		m[1] += hi
	} else if hi > 0 {
		// No match.  Wrap to beginning of data.
		m = re.FindIndex(data)
	}
	if len(m) == 0 {
		return 0, 0, errors.New("no match for " + pattern)
	}
	return m[0], m[1], nil
}


================================================
FILE: present/caption.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import "strings"

func init() {
	Register("caption", parseCaption)
}

type Caption struct {
	Cmd  string // original command from present source
	Text string
}

func (c Caption) PresentCmd() string   { return c.Cmd }
func (c Caption) TemplateName() string { return "caption" }

func parseCaption(_ *Context, _ string, _ int, cmd string) (Elem, error) {
	text := strings.TrimSpace(strings.TrimPrefix(cmd, ".caption"))
	return Caption{cmd, text}, nil
}


================================================
FILE: present/code.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"bufio"
	"bytes"
	"fmt"
	"html/template"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
)

// PlayEnabled specifies whether runnable playground snippets should be
// displayed in the present user interface.
var PlayEnabled = false

// TODO(adg): replace the PlayEnabled flag with something less spaghetti-like.
// Instead this will probably be determined by a template execution Context
// value that contains various global metadata required when rendering
// templates.

// NotesEnabled specifies whether presenter notes should be displayed in the
// present user interface.
var NotesEnabled = false

func init() {
	Register("code", parseCode)
	Register("play", parseCode)
}

type Code struct {
	Cmd      string // original command from present source
	Text     template.HTML
	Play     bool   // runnable code
	Edit     bool   // editable code
	FileName string // file name
	Ext      string // file extension
	Raw      []byte // content of the file
}

func (c Code) PresentCmd() string   { return c.Cmd }
func (c Code) TemplateName() string { return "code" }

// The input line is a .code or .play entry with a file name and an optional HLfoo marker on the end.
// Anything between the file and HL (if any) is an address expression, which we treat as a string here.
// We pick off the HL first, for easy parsing.
var (
	highlightRE = regexp.MustCompile(`\s+HL([a-zA-Z0-9_]+)?$`)
	hlCommentRE = regexp.MustCompile(`(.+) // HL(.*)$`)
	codeRE      = regexp.MustCompile(`\.(code|play)\s+((?:(?:-edit|-numbers)\s+)*)([^\s]+)(?:\s+(.*))?$`)
)

// parseCode parses a code present directive. Its syntax:
//
//	.code [-numbers] [-edit] <filename> [address] [highlight]
//
// The directive may also be ".play" if the snippet is executable.
func parseCode(ctx *Context, sourceFile string, sourceLine int, cmd string) (Elem, error) {
	cmd = strings.TrimSpace(cmd)
	origCmd := cmd

	// Pull off the HL, if any, from the end of the input line.
	highlight := ""
	if hl := highlightRE.FindStringSubmatchIndex(cmd); len(hl) == 4 {
		if hl[2] < 0 || hl[3] < 0 {
			return nil, fmt.Errorf("%s:%d invalid highlight syntax", sourceFile, sourceLine)
		}
		highlight = cmd[hl[2]:hl[3]]
		cmd = cmd[:hl[2]-2]
	}

	// Parse the remaining command line.
	// Arguments:
	// args[0]: whole match
	// args[1]:  .code/.play
	// args[2]: flags ("-edit -numbers")
	// args[3]: file name
	// args[4]: optional address
	args := codeRE.FindStringSubmatch(cmd)
	if len(args) != 5 {
		return nil, fmt.Errorf("%s:%d: syntax error for .code/.play invocation", sourceFile, sourceLine)
	}
	command, flags, file, addr := args[1], args[2], args[3], strings.TrimSpace(args[4])
	play := command == "play" && PlayEnabled

	// Read in code file and (optionally) match address.
	filename := filepath.Join(filepath.Dir(sourceFile), file)
	textBytes, err := ctx.ReadFile(filename)
	if err != nil {
		return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
	}
	lo, hi, err := addrToByteRange(addr, 0, textBytes)
	if err != nil {
		return nil, fmt.Errorf("%s:%d: %v", sourceFile, sourceLine, err)
	}
	if lo > hi {
		// The search in addrToByteRange can wrap around so we might
		// end up with the range ending before its starting point
		hi, lo = lo, hi
	}

	// Acme pattern matches can stop mid-line,
	// so run to end of line in both directions if not at line start/end.
	for lo > 0 && textBytes[lo-1] != '\n' {
		lo--
	}
	if hi > 0 {
		for hi < len(textBytes) && textBytes[hi-1] != '\n' {
			hi++
		}
	}

	lines := codeLines(textBytes, lo, hi)

	data := &codeTemplateData{
		Lines:   formatLines(lines, highlight),
		Edit:    strings.Contains(flags, "-edit"),
		Numbers: strings.Contains(flags, "-numbers"),
	}

	// Include before and after in a hidden span for playground code.
	if play {
		data.Prefix = textBytes[:lo]
		data.Suffix = textBytes[hi:]
	}

	var buf bytes.Buffer
	if err := codeTemplate.Execute(&buf, data); err != nil {
		return nil, err
	}
	return Code{
		Cmd:      origCmd,
		Text:     template.HTML(buf.String()),
		Play:     play,
		Edit:     data.Edit,
		FileName: filepath.Base(filename),
		Ext:      filepath.Ext(filename),
		Raw:      rawCode(lines),
	}, nil
}

// formatLines returns a new slice of codeLine with the given lines
// replacing tabs with spaces and adding highlighting where needed.
func formatLines(lines []codeLine, highlight string) []codeLine {
	formatted := make([]codeLine, len(lines))
	for i, line := range lines {
		// Replace tabs with spaces, which work better in HTML.
		line.L = strings.Replace(line.L, "\t", "    ", -1)

		// Highlight lines that end with "// HL[highlight]"
		// and strip the magic comment.
		if m := hlCommentRE.FindStringSubmatch(line.L); m != nil {
			line.L = m[1]
			line.HL = m[2] == highlight
		}

		formatted[i] = line
	}
	return formatted
}

// rawCode returns the code represented by the given codeLines without any kind
// of formatting.
func rawCode(lines []codeLine) []byte {
	b := new(bytes.Buffer)
	for _, line := range lines {
		b.WriteString(line.L)
		b.WriteByte('\n')
	}
	return b.Bytes()
}

type codeTemplateData struct {
	Lines          []codeLine
	Prefix, Suffix []byte
	Edit, Numbers  bool
}

var leadingSpaceRE = regexp.MustCompile(`^[ \t]*`)

var codeTemplate = template.Must(template.New("code").Funcs(template.FuncMap{
	"trimSpace":    strings.TrimSpace,
	"leadingSpace": leadingSpaceRE.FindString,
}).Parse(codeTemplateHTML))

const codeTemplateHTML = `
{{with .Prefix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}

<pre{{if .Edit}} contenteditable="true" spellcheck="false"{{end}}{{if .Numbers}} class="numbers"{{end}}>{{/*
	*/}}{{range .Lines}}<span num="{{.N}}">{{/*
	*/}}{{if .HL}}{{leadingSpace .L}}<b>{{trimSpace .L}}</b>{{/*
	*/}}{{else}}{{.L}}{{end}}{{/*
*/}}</span>
{{end}}</pre>
{{with .Suffix}}<pre style="display: none"><span>{{printf "%s" .}}</span></pre>{{end -}}
`

// codeLine represents a line of code extracted from a source file.
type codeLine struct {
	L  string // The line of code.
	N  int    // The line number from the source file.
	HL bool   // Whether the line should be highlighted.
}

// codeLines takes a source file and returns the lines that
// span the byte range specified by start and end.
// It discards lines that end in "OMIT".
func codeLines(src []byte, start, end int) (lines []codeLine) {
	startLine := 1
	for i, b := range src {
		if i == start {
			break
		}
		if b == '\n' {
			startLine++
		}
	}
	s := bufio.NewScanner(bytes.NewReader(src[start:end]))
	for n := startLine; s.Scan(); n++ {
		l := s.Text()
		if strings.HasSuffix(l, "OMIT") {
			continue
		}
		lines = append(lines, codeLine{L: l, N: n})
	}
	// Trim leading and trailing blank lines.
	for len(lines) > 0 && len(lines[0].L) == 0 {
		lines = lines[1:]
	}
	for len(lines) > 0 && len(lines[len(lines)-1].L) == 0 {
		lines = lines[:len(lines)-1]
	}
	return
}

func parseArgs(name string, line int, args []string) (res []any, err error) {
	res = make([]any, len(args))
	for i, v := range args {
		if len(v) == 0 {
			return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
		}
		switch v[0] {
		case '0', '1', '2', '3', '4', '5', '6', '7', '8', '9':
			n, err := strconv.Atoi(v)
			if err != nil {
				return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
			}
			res[i] = n
		case '/':
			if len(v) < 2 || v[len(v)-1] != '/' {
				return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
			}
			res[i] = v
		case '$':
			res[i] = "$"
		case '_':
			if len(v) == 1 {
				// Do nothing; "_" indicates an intentionally empty parameter.
				break
			}
			fallthrough
		default:
			return nil, fmt.Errorf("%s:%d bad code argument %q", name, line, v)
		}
	}
	return
}


================================================
FILE: present/code_test.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"html/template"
	"strings"
	"testing"
)

func TestParseCode(t *testing.T) {
	// Enable play but revert the change at the end.
	defer func(play bool) { PlayEnabled = play }(PlayEnabled)
	PlayEnabled = true

	helloTest := []byte(`
package main

import "fmt"

func main() {
	fmt.Println("hello, test")
}
`)
	helloTestHTML := template.HTML(`
<pre><span num="2">package main</span>
<span num="3"></span>
<span num="4">import &#34;fmt&#34;</span>
<span num="5"></span>
<span num="6">func main() {</span>
<span num="7">    fmt.Println(&#34;hello, test&#34;)</span>
<span num="8">}</span>
</pre>
`)
	helloTestHL := []byte(`
package main

import "fmt" // HLimport

func main() { // HLfunc
	fmt.Println("hello, test") // HL
}
`)
	highlight := func(h template.HTML, s string) template.HTML {
		return template.HTML(strings.Replace(string(h), s, "<b>"+s+"</b>", -1))
	}
	read := func(b []byte, err error) func(string) ([]byte, error) {
		return func(string) ([]byte, error) { return b, err }
	}

	tests := []struct {
		name       string
		readFile   func(string) ([]byte, error)
		sourceFile string
		cmd        string
		err        string
		Code
	}{
		{
			name:       "all code, no play",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Raw:      helloTest,
				Text:     helloTestHTML,
			},
		},
		{
			name:       "all code, play",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".play main.go",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Play:     true,
				Raw:      helloTest,
				Text:     helloTestHTML,
			},
		},
		{
			name:       "all code, highlighted",
			readFile:   read(helloTestHL, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Raw:      helloTestHL,
				Text:     highlight(helloTestHTML, "fmt.Println(&#34;hello, test&#34;)"),
			},
		},
		{
			name:       "highlight only func",
			readFile:   read(helloTestHL, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go HLfunc",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Play:     false,
				Raw:      []byte("package main\n\nimport \"fmt\" // HLimport\n\nfunc main() { // HLfunc\n\tfmt.Println(\"hello, test\") // HL\n}"),
				Text:     highlight(helloTestHTML, "func main() {"),
			},
		},
		{
			name:       "bad highlight syntax",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go HL",
			err:        "invalid highlight syntax",
		},
		{
			name:       "error reading file",
			readFile:   read(nil, fmt.Errorf("nope")),
			sourceFile: "main.go",
			cmd:        ".code main.go",
			err:        "main.go:0: nope",
		},
		{
			name:       "from func main to the end",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go /func main/,",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Play:     false,
				Raw:      []byte("func main() {\n\tfmt.Println(\"hello, test\")\n}"),
				Text:     "<pre><span num=\"6\">func main() {</span>\n<span num=\"7\">    fmt.Println(&#34;hello, test&#34;)</span>\n<span num=\"8\">}</span>\n</pre>",
			},
		},
		{
			name:       "just func main",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go /func main/",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Play:     false,
				Raw:      []byte("func main() {"),
				Text:     "<pre><span num=\"6\">func main() {</span>\n</pre>",
			},
		},
		{
			name:       "bad address",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code main.go /function main/",
			err:        "main.go:0: no match for function main",
		},
		{
			name:       "all code with numbers",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code -numbers main.go",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Raw:      helloTest,
				// Replacing the first "<pre>"
				Text: "<pre class=\"numbers\">" + helloTestHTML[6:],
			},
		},
		{
			name:       "all code editable",
			readFile:   read(helloTest, nil),
			sourceFile: "main.go",
			cmd:        ".code -edit main.go",
			Code: Code{
				Ext:      ".go",
				FileName: "main.go",
				Raw:      helloTest,
				Text:     "<pre contenteditable=\"true\" spellcheck=\"false\">" + helloTestHTML[6:],
			},
		},
	}

	trimHTML := func(t template.HTML) string { return strings.TrimSpace(string(t)) }
	trimBytes := func(b []byte) string { return strings.TrimSpace(string(b)) }

	for _, tt := range tests {
		ctx := &Context{tt.readFile}
		e, err := parseCode(ctx, tt.sourceFile, 0, tt.cmd)
		if err != nil {
			if tt.err == "" {
				t.Errorf("%s: unexpected error %v", tt.name, err)
			} else if !strings.Contains(err.Error(), tt.err) {
				t.Errorf("%s: expected error %s; got %v", tt.name, tt.err, err)
			}
			continue
		}
		if tt.err != "" {
			t.Errorf("%s: expected error %s; but got none", tt.name, tt.err)
			continue
		}
		c, ok := e.(Code)
		if !ok {
			t.Errorf("%s: expected a Code value; got %T", tt.name, e)
			continue
		}
		if c.FileName != tt.FileName {
			t.Errorf("%s: expected FileName %s; got %s", tt.name, tt.FileName, c.FileName)
		}
		if c.Ext != tt.Ext {
			t.Errorf("%s: expected Ext %s; got %s", tt.name, tt.Ext, c.Ext)
		}
		if c.Play != tt.Play {
			t.Errorf("%s: expected Play %v; got %v", tt.name, tt.Play, c.Play)
		}
		if got, wants := trimBytes(c.Raw), trimBytes(tt.Raw); got != wants {
			t.Errorf("%s: expected Raw \n%q\n; got \n%q\n", tt.name, wants, got)
		}
		if got, wants := trimHTML(c.Text), trimHTML(tt.Text); got != wants {
			t.Errorf("%s: expected Text \n%q\n; got \n%q\n", tt.name, wants, got)
		}
	}
}


================================================
FILE: present/doc.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

/*
Package present implements parsing and rendering of present files,
which can be slide presentations as in golang.org/x/tools/cmd/present
or articles as in golang.org/x/blog (the Go blog).

# File Format

Present files begin with a header giving the title of the document
and other metadata, which looks like:

	# Title of document
	Subtitle of document
	15:04 2 Jan 2006
	Tags: foo, bar, baz
	Summary: This is a great document you want to read.
	OldURL: former-path-for-this-doc

The "# " prefix before the title indicates that this is
a Markdown-enabled present file: it uses
Markdown for text markup in the body of the file.
If the "# " prefix is missing, the file uses
legacy present markup, described below.

The date line may be written without a time:

	2 Jan 2006

In this case, the time will be interpreted as 10am UTC on that date.

The tags line is a comma-separated list of tags that may be used to categorize
the document.

The summary line gives a short summary used in blog feeds.

The old URL line, which may be repeated, gives an older (perhaps relative) URL
for this document.
A server might use these to generate appropriate redirects.

Only the title is required;
the subtitle, date, tags, summary, and old URL lines are optional.
In Markdown-enabled present, the summary defaults to being empty.
In legacy present, the summary defaults to the first paragraph of text.

After the header come zero or more author blocks, like this:

	Author Name
	Job title, Company
	joe@example.com
	https://url/
	@twitter_name

The first line of the author block is conventionally the author name.
Otherwise, the author section may contain a mixture of text, twitter names, and links.
For slide presentations, only the plain text lines will be displayed on the
first slide.

If multiple author blocks are listed, each new block must be preceded
by its own blank line.

After the author blocks come the presentation slides or article sections,
which can in turn have subsections.
In Markdown-enabled present files, each slide or section begins with a "##" header line,
subsections begin with a "###" header line, and so on.
In legacy present files, each slide or section begins with a "*" header line,
subsections begin with a "**" header line, and so on.

In addition to the marked-up text in a section (or subsection),
a present file can contain present command invocations, each of which begins
with a dot, as in:

	.code x.go /^func main/,/^}/
	.play y.go
	.image image.jpg
	.background image.jpg
	.iframe https://foo
	.link https://foo label
	.html file.html
	.caption _Gopher_ by [[https://instagram.com/reneefrench][Renee French]]

Other than the commands, the text in a section is interpreted
either as Markdown or as legacy present markup.

# Markdown Syntax

Markdown typically means the generic name for a family of similar markup languages.
The specific variant used in present is CommonMark.
See https://commonmark.org/help/tutorial/ for a quick tutorial.

In Markdown-enabled present,
section headings can end in {#name} to set the HTML anchor ID for the heading to "name".

Lines beginning with "//" (outside of code blocks, of course)
are treated as present comments and have no effect.

Lines beginning with ": " are treated as speaker notes, described below.

Example:

	# Title of Talk

	My Name
	9 Mar 2020
	me@example.com

	## Title of Slide or Section (must begin with ##)

	Some Text

	### Subsection {#anchor}

	- bullets
	- more bullets
	- a bullet continued
	  on the next line

	#### Sub-subsection

	Some More text

		Preformatted text (code block)
		is indented (by one tab, or four spaces)

	Further Text, including command invocations.

	## Section 2: Example formatting {#fmt}

	Formatting:

	_italic_
	// A comment that is completely ignored.
	: Speaker notes.
	**bold**
	`program`
	Markup—_especially italic text_—can easily be overused.
	_Why use scoped\_ptr_? Use plain **\*ptr** instead.

	Visit [the Go home page](https://golang.org/).

# Legacy Present Syntax

Compared to Markdown,
in legacy present
slides/sections use "*" instead of "##",
whole-line comments begin with "#" instead of "//",
bullet lists can only contain single (possibly wrapped) text lines,
and the font styling and link syntaxes are subtly different.

Example:

	Title of Talk

	My Name
	1 Jan 2013
	me@example.com

	* Title of Slide or Section (must begin with *)

	Some Text

	** Subsection

	- bullets
	- more bullets
	- a bullet continued
	  on the next line (indented at least one space)

	*** Sub-subsection

	Some More text

	  Preformatted text (code block)
	  is indented (however you like)

	Further Text, including command invocations.

	* Section 2: Example formatting

	Formatting:

	_italic_
	*bold*
	`program`
	Markup—_especially_italic_text_—can easily be overused.
	_Why_use_scoped__ptr_? Use plain ***ptr* instead.

	Visit [[https://golang.org][the Go home page]].

Within the input for plain text or lists, text bracketed by font
markers will be presented in italic, bold, or program font.
Marker characters are _ (italic), * (bold) and ` (program font).
An opening marker must be preceded by a space or punctuation
character or else be at start of a line; similarly, a closing
marker must be followed by a space or punctuation character or
else be at the end of a line. Unmatched markers appear as plain text.
There must be no spaces between markers. Within marked text,
a single marker character becomes a space and a doubled single
marker quotes the marker character.

Links can be included in any text with either explicit labels
or the URL itself as the label. For example:

	[[url][label]]
	[[url]]

# Command Invocations

A number of special commands are available through invocations
in the input text. Each such invocation contains a period as the
first character on the line, followed immediately by the name of
the function, followed by any arguments. A typical invocation might
be

	.play demo.go /^func show/,/^}/

(except that the ".play" must be at the beginning of the line and
not be indented as in this comment.)

Here follows a description of the functions:

code:

Injects program source into the output by extracting code from files
and injecting them as HTML-escaped <pre> blocks.  The argument is
a file name followed by an optional address that specifies what
section of the file to display. The address syntax is similar in
its simplest form to that of ed, but comes from sam and is more
general. See

	https://plan9.io/sys/doc/sam/sam.html Table II

for full details. The displayed block is always rounded out to a
full line at both ends.

If no pattern is present, the entire file is displayed.

Any line in the program that ends with the four characters

	OMIT

is deleted from the source before inclusion, making it easy
to write things like

	.code test.go /START OMIT/,/END OMIT/

to find snippets like this

	tedious_code = boring_function()
	// START OMIT
	interesting_code = fascinating_function()
	// END OMIT

and see only this:

	interesting_code = fascinating_function()

Also, inside the displayed text a line that ends

	// HL

will be highlighted in the display. A highlighting mark may have a
suffix word, such as

	// HLxxx

Such highlights are enabled only if the code invocation ends with
"HL" followed by the word:

	.code test.go /^type Foo/,/^}/ HLxxx

The .code function may take one or more flags immediately preceding
the filename. This command shows test.go in an editable text area:

	.code -edit test.go

This command shows test.go with line numbers:

	.code -numbers test.go

play:

The function "play" is the same as "code" but puts a button
on the displayed source so the program can be run from the browser.
Although only the selected text is shown, all the source is included
in the HTML output so it can be presented to the compiler.

link:

Create a hyperlink. The syntax is 1 or 2 space-separated arguments.
The first argument is always the HTTP URL.  If there is a second
argument, it is the text label to display for this link.

	.link https://golang.org golang.org

image:

The template uses the function "image" to inject picture files.

The syntax is simple: 1 or 3 space-separated arguments.
The first argument is always the file name.
If there are more arguments, they are the height and width;
both must be present, or substituted with an underscore.
Replacing a dimension argument with the underscore parameter
preserves the aspect ratio of the image when scaling.

	.image images/betsy.jpg 100 200
	.image images/janet.jpg _ 300

video:

The template uses the function "video" to inject video files.

The syntax is simple: 2 or 4 space-separated arguments.
The first argument is always the file name.
The second argument is always the file content-type.
If there are more arguments, they are the height and width;
both must be present, or substituted with an underscore.
Replacing a dimension argument with the underscore parameter
preserves the aspect ratio of the video when scaling.

	.video videos/evangeline.mp4 video/mp4 400 600

	.video videos/mabel.ogg video/ogg 500 _

background:

The template uses the function "background" to set the background image for
a slide.  The only argument is the file name of the image.

	.background images/susan.jpg

caption:

The template uses the function "caption" to inject figure captions.

The text after ".caption" is embedded in a figcaption element after
processing styling and links as in standard text lines.

	.caption _Gopher_ by [[https://instagram.com/reneefrench][Renee French]]

iframe:

The function "iframe" injects iframes (pages inside pages).
Its syntax is the same as that of image.

html:

The function html includes the contents of the specified file as
unescaped HTML. This is useful for including custom HTML elements
that cannot be created using only the slide format.
It is your responsibility to make sure the included HTML is valid and safe.

	.html file.html

# Presenter Notes

Lines that begin with ": " are treated as presenter notes,
in both Markdown and legacy present syntax.
By default, presenter notes are collected but ignored.

When running the present command with -notes,
typing 'N' in your browser displaying your slides
will create a second window displaying the notes.
The second window is completely synced with the main
window, except that presenter notes are only visible in the second window.

Notes may appear anywhere within the slide text. For example:

	## Title of slide

	Some text.

	: Presenter notes (first paragraph)

	Some more text.

	: Presenter notes (subsequent paragraph(s))
*/
package present // import "golang.org/x/tools/present"


================================================
FILE: present/html.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"errors"
	"html/template"
	"path/filepath"
	"strings"
)

func init() {
	Register("html", parseHTML)
}

func parseHTML(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
	p := strings.Fields(text)
	if len(p) != 2 {
		return nil, errors.New("invalid .html args")
	}
	name := filepath.Join(filepath.Dir(fileName), p[1])
	b, err := ctx.ReadFile(name)
	if err != nil {
		return nil, err
	}
	return HTML{text, template.HTML(b)}, nil
}

type HTML struct {
	Cmd string // original command from present source
	template.HTML
}

func (s HTML) PresentCmd() string   { return s.Cmd }
func (s HTML) TemplateName() string { return "html" }


================================================
FILE: present/iframe.go
================================================
// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"strings"
)

func init() {
	Register("iframe", parseIframe)
}

type Iframe struct {
	Cmd    string // original command from present source
	URL    string
	Width  int
	Height int
}

func (i Iframe) PresentCmd() string   { return i.Cmd }
func (i Iframe) TemplateName() string { return "iframe" }

func parseIframe(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
	args := strings.Fields(text)
	if len(args) < 2 {
		return nil, fmt.Errorf("incorrect iframe invocation: %q", text)
	}
	i := Iframe{Cmd: text, URL: args[1]}
	a, err := parseArgs(fileName, lineno, args[2:])
	if err != nil {
		return nil, err
	}
	switch len(a) {
	case 0:
		// no size parameters
	case 2:
		if v, ok := a[0].(int); ok {
			i.Height = v
		}
		if v, ok := a[1].(int); ok {
			i.Width = v
		}
	default:
		return nil, fmt.Errorf("incorrect iframe invocation: %q", text)
	}
	return i, nil
}


================================================
FILE: present/image.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"strings"
)

func init() {
	Register("image", parseImage)
}

type Image struct {
	Cmd    string // original command from present source
	URL    string
	Width  int
	Height int
}

func (i Image) PresentCmd() string   { return i.Cmd }
func (i Image) TemplateName() string { return "image" }

func parseImage(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
	args := strings.Fields(text)
	if len(args) < 2 {
		return nil, fmt.Errorf("incorrect image invocation: %q", text)
	}
	img := Image{Cmd: text, URL: args[1]}
	a, err := parseArgs(fileName, lineno, args[2:])
	if err != nil {
		return nil, err
	}
	switch len(a) {
	case 0:
		// no size parameters
	case 2:
		// If a parameter is empty (underscore) or invalid
		// leave the field set to zero. The "image" action
		// template will then omit that img tag attribute and
		// the browser will calculate the value to preserve
		// the aspect ratio.
		if v, ok := a[0].(int); ok {
			img.Height = v
		}
		if v, ok := a[1].(int); ok {
			img.Width = v
		}
	default:
		return nil, fmt.Errorf("incorrect image invocation: %q", text)
	}
	return img, nil
}


================================================
FILE: present/link.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"log"
	"net/url"
	"strings"
)

func init() {
	Register("link", parseLink)
}

type Link struct {
	Cmd   string // original command from present source
	URL   *url.URL
	Label string
}

func (l Link) PresentCmd() string   { return l.Cmd }
func (l Link) TemplateName() string { return "link" }

func parseLink(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
	args := strings.Fields(text)
	if len(args) < 2 {
		return nil, fmt.Errorf("link element must have at least 2 arguments")
	}
	url, err := url.Parse(args[1])
	if err != nil {
		return nil, err
	}
	label := ""
	if len(args) > 2 {
		label = strings.Join(args[2:], " ")
	} else {
		scheme := url.Scheme + "://"
		if url.Scheme == "mailto" {
			scheme = "mailto:"
		}
		label = strings.Replace(url.String(), scheme, "", 1)
	}
	return Link{text, url, label}, nil
}

func renderLink(href, text string) string {
	text = font(text)
	if text == "" {
		text = href
	}
	// Open links in new window only when their url is absolute.
	target := "_blank"
	if u, err := url.Parse(href); err != nil {
		log.Println("renderLink parsing url:", err)
	} else if !u.IsAbs() || u.Scheme == "javascript" {
		target = "_self"
	}

	return fmt.Sprintf(`<a href="%s" target="%s">%s</a>`, href, target, text)
}

// parseInlineLink parses an inline link at the start of s, and returns
// a rendered HTML link and the total length of the raw inline link.
// If no inline link is present, it returns all zeroes.
func parseInlineLink(s string) (link string, length int) {
	if !strings.HasPrefix(s, "[[") {
		return
	}
	end := strings.Index(s, "]]")
	if end == -1 {
		return
	}
	urlEnd := strings.Index(s, "]")
	rawURL := s[2:urlEnd]
	const badURLChars = `<>"{}|\^[] ` + "`" // per RFC2396 section 2.4.3
	if strings.ContainsAny(rawURL, badURLChars) {
		return
	}
	if urlEnd == end {
		simpleURL := ""
		url, err := url.Parse(rawURL)
		if err == nil {
			// If the URL is http://foo.com, drop the http://
			// In other words, render [[http://golang.org]] as:
			//   <a href="http://golang.org">golang.org</a>
			if after, ok := strings.CutPrefix(rawURL, url.Scheme+"://"); ok {
				simpleURL = after
			} else if after, ok := strings.CutPrefix(rawURL, url.Scheme+":"); ok {
				simpleURL = after
			}
		}
		return renderLink(rawURL, simpleURL), end + 2
	}
	if s[urlEnd:urlEnd+2] != "][" {
		return
	}
	text := s[urlEnd+2 : end]
	return renderLink(rawURL, text), end + 2
}


================================================
FILE: present/link_test.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import "testing"

func TestInlineParsing(t *testing.T) {
	var tests = []struct {
		in     string
		link   string
		text   string
		length int
	}{
		{"[[http://golang.org]]", "http://golang.org", "golang.org", 21},
		{"[[http://golang.org][]]", "http://golang.org", "http://golang.org", 23},
		{"[[http://golang.org]] this is ignored", "http://golang.org", "golang.org", 21},
		{"[[http://golang.org][link]]", "http://golang.org", "link", 27},
		{"[[http://golang.org][two words]]", "http://golang.org", "two words", 32},
		{"[[http://golang.org][*link*]]", "http://golang.org", "<b>link</b>", 29},
		{"[[http://bad[url]]", "", "", 0},
		{"[[http://golang.org][a [[link]] ]]", "http://golang.org", "a [[link", 31},
		{"[[http:// *spaces* .com]]", "", "", 0},
		{"[[http://bad`char.com]]", "", "", 0},
		{" [[http://google.com]]", "", "", 0},
		{"[[mailto:gopher@golang.org][Gopher]]", "mailto:gopher@golang.org", "Gopher", 36},
		{"[[mailto:gopher@golang.org]]", "mailto:gopher@golang.org", "gopher@golang.org", 28},
	}

	for i, test := range tests {
		link, length := parseInlineLink(test.in)
		if length == 0 && test.length == 0 {
			continue
		}
		if a := renderLink(test.link, test.text); length != test.length || link != a {
			t.Errorf("#%d: parseInlineLink(%q):\ngot\t%q, %d\nwant\t%q, %d", i, test.in, link, length, a, test.length)
		}
	}
}


================================================
FILE: present/parse.go
================================================
// Copyright 2011 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"bufio"
	"bytes"
	"errors"
	"fmt"
	"html/template"
	"io"
	"log"
	"net/url"
	"os"
	"regexp"
	"slices"
	"strings"
	"time"
	"unicode"
	"unicode/utf8"

	"github.com/yuin/goldmark"
	"github.com/yuin/goldmark/ast"
	"github.com/yuin/goldmark/renderer/html"
	"github.com/yuin/goldmark/text"
)

var (
	parsers = make(map[string]ParseFunc)
	funcs   = template.FuncMap{}
)

// Template returns an empty template with the action functions in its FuncMap.
func Template() *template.Template {
	return template.New("").Funcs(funcs)
}

// Render renders the doc to the given writer using the provided template.
func (d *Doc) Render(w io.Writer, t *template.Template) error {
	data := struct {
		*Doc
		Template     *template.Template
		PlayEnabled  bool
		NotesEnabled bool
	}{d, t, PlayEnabled, NotesEnabled}
	return t.ExecuteTemplate(w, "root", data)
}

// Render renders the section to the given writer using the provided template.
func (s *Section) Render(w io.Writer, t *template.Template) error {
	data := struct {
		*Section
		Template    *template.Template
		PlayEnabled bool
	}{s, t, PlayEnabled}
	return t.ExecuteTemplate(w, "section", data)
}

type ParseFunc func(ctx *Context, fileName string, lineNumber int, inputLine string) (Elem, error)

// Register binds the named action, which does not begin with a period, to the
// specified parser to be invoked when the name, with a period, appears in the
// present input text.
func Register(name string, parser ParseFunc) {
	if len(name) == 0 || name[0] == ';' {
		panic("bad name in Register: " + name)
	}
	parsers["."+name] = parser
}

// Doc represents an entire document.
type Doc struct {
	Title      string
	Subtitle   string
	Summary    string
	Time       time.Time
	Authors    []Author
	TitleNotes []string
	Sections   []Section
	Tags       []string
	OldURL     []string
}

// Author represents the person who wrote and/or is presenting the document.
type Author struct {
	Elem []Elem
}

// TextElem returns the first text elements of the author details.
// This is used to display the author' name, job title, and company
// without the contact details.
func (p *Author) TextElem() (elems []Elem) {
	for _, el := range p.Elem {
		if _, ok := el.(Text); !ok {
			break
		}
		elems = append(elems, el)
	}
	return
}

// Section represents a section of a document (such as a presentation slide)
// comprising a title and a list of elements.
type Section struct {
	Number  []int
	Title   string
	ID      string // HTML anchor ID
	Elem    []Elem
	Notes   []string
	Classes []string
	Styles  []string
}

// HTMLAttributes for the section
func (s Section) HTMLAttributes() template.HTMLAttr {
	if len(s.Classes) == 0 && len(s.Styles) == 0 {
		return ""
	}

	var class string
	if len(s.Classes) > 0 {
		class = fmt.Sprintf(`class=%q`, strings.Join(s.Classes, " "))
	}
	var style string
	if len(s.Styles) > 0 {
		style = fmt.Sprintf(`style=%q`, strings.Join(s.Styles, " "))
	}
	return template.HTMLAttr(strings.Join([]string{class, style}, " "))
}

// Sections contained within the section.
func (s Section) Sections() (sections []Section) {
	for _, e := range s.Elem {
		if section, ok := e.(Section); ok {
			sections = append(sections, section)
		}
	}
	return
}

// Level returns the level of the given section.
// The document title is level 1, main section 2, etc.
func (s Section) Level() int {
	return len(s.Number) + 1
}

// FormattedNumber returns a string containing the concatenation of the
// numbers identifying a Section.
func (s Section) FormattedNumber() string {
	b := &bytes.Buffer{}
	for _, n := range s.Number {
		fmt.Fprintf(b, "%v.", n)
	}
	return b.String()
}

func (s Section) TemplateName() string { return "section" }

// Elem defines the interface for a present element. That is, something that
// can provide the name of the template used to render the element.
type Elem interface {
	TemplateName() string
}

// renderElem implements the elem template function, used to render
// sub-templates.
func renderElem(t *template.Template, e Elem) (template.HTML, error) {
	var data any = e
	if s, ok := e.(Section); ok {
		data = struct {
			Section
			Template *template.Template
		}{s, t}
	}
	return execTemplate(t, e.TemplateName(), data)
}

// pageNum derives a page number from a section.
func pageNum(s Section, offset int) int {
	if len(s.Number) == 0 {
		return offset
	}
	return s.Number[0] + offset
}

func init() {
	funcs["elem"] = renderElem
	funcs["pagenum"] = pageNum
}

// execTemplate is a helper to execute a template and return the output as a
// template.HTML value.
func execTemplate(t *template.Template, name string, data any) (template.HTML, error) {
	b := new(bytes.Buffer)
	err := t.ExecuteTemplate(b, name, data)
	if err != nil {
		return "", err
	}
	return template.HTML(b.String()), nil
}

// Text represents an optionally preformatted paragraph.
type Text struct {
	Lines []string
	Pre   bool
	Raw   string // original text, for Pre==true
}

func (t Text) TemplateName() string { return "text" }

// List represents a bulleted list.
type List struct {
	Bullet []string
}

func (l List) TemplateName() string { return "list" }

// Lines is a helper for parsing line-based input.
type Lines struct {
	line    int // 0 indexed, so has 1-indexed number of last line returned
	text    []string
	comment string
}

func readLines(r io.Reader) (*Lines, error) {
	var lines []string
	s := bufio.NewScanner(r)
	for s.Scan() {
		lines = append(lines, s.Text())
	}
	if err := s.Err(); err != nil {
		return nil, err
	}
	return &Lines{0, lines, "#"}, nil
}

func (l *Lines) next() (text string, ok bool) {
	for {
		current := l.line
		l.line++
		if current >= len(l.text) {
			return "", false
		}
		text = l.text[current]
		// Lines starting with l.comment are comments.
		if l.comment == "" || !strings.HasPrefix(text, l.comment) {
			ok = true
			break
		}
	}
	return
}

func (l *Lines) back() {
	l.line--
}

func (l *Lines) nextNonEmpty() (text string, ok bool) {
	for {
		text, ok = l.next()
		if !ok {
			return
		}
		if len(text) > 0 {
			break
		}
	}
	return
}

// A Context specifies the supporting context for parsing a presentation.
type Context struct {
	// ReadFile reads the file named by filename and returns the contents.
	ReadFile func(filename string) ([]byte, error)
}

// ParseMode represents flags for the Parse function.
type ParseMode int

const (
	// If set, parse only the title and subtitle.
	TitlesOnly ParseMode = 1
)

// Parse parses a document from r.
func (ctx *Context) Parse(r io.Reader, name string, mode ParseMode) (*Doc, error) {
	doc := new(Doc)
	lines, err := readLines(r)
	if err != nil {
		return nil, err
	}

	// Detect Markdown-enabled vs legacy present file.
	// Markdown-enabled files have a title line beginning with "# "
	// (like preprocessed C files of yore).
	isMarkdown := false
	for i := lines.line; i < len(lines.text); i++ {
		line := lines.text[i]
		if line == "" {
			continue
		}
		isMarkdown = strings.HasPrefix(line, "# ")
		break
	}

	sectionPrefix := "*"
	if isMarkdown {
		sectionPrefix = "##"
		lines.comment = "//"
	}

	for i := lines.line; i < len(lines.text); i++ {
		if strings.HasPrefix(lines.text[i], sectionPrefix) {
			break
		}

		if isSpeakerNote(lines.text[i]) {
			doc.TitleNotes = append(doc.TitleNotes, trimSpeakerNote(lines.text[i]))
		}
	}

	err = parseHeader(doc, isMarkdown, lines)
	if err != nil {
		return nil, err
	}
	if mode&TitlesOnly != 0 {
		return doc, nil
	}

	// Authors
	if doc.Authors, err = parseAuthors(name, sectionPrefix, lines); err != nil {
		return nil, err
	}

	// Sections
	if doc.Sections, err = parseSections(ctx, name, sectionPrefix, lines, []int{}); err != nil {
		return nil, err
	}

	return doc, nil
}

// Parse parses a document from r. Parse reads assets used by the presentation
// from the file system using os.ReadFile.
func Parse(r io.Reader, name string, mode ParseMode) (*Doc, error) {
	ctx := Context{ReadFile: os.ReadFile}
	return ctx.Parse(r, name, mode)
}

// isHeading matches any section heading.
var (
	isHeadingLegacy   = regexp.MustCompile(`^\*+( |$)`)
	isHeadingMarkdown = regexp.MustCompile(`^\#+( |$)`)
)

// lesserHeading returns true if text is a heading of a lesser or equal level
// than that denoted by prefix.
func lesserHeading(isHeading *regexp.Regexp, text, prefix string) bool {
	return isHeading.MatchString(text) && !strings.HasPrefix(text, prefix+prefix[:1])
}

// parseSections parses Sections from lines for the section level indicated by
// number (a nil number indicates the top level).
func parseSections(ctx *Context, name, prefix string, lines *Lines, number []int) ([]Section, error) {
	isMarkdown := prefix[0] == '#'
	isHeading := isHeadingLegacy
	if isMarkdown {
		isHeading = isHeadingMarkdown
	}
	var sections []Section
	for i := 1; ; i++ {
		// Next non-empty line is title.
		text, ok := lines.nextNonEmpty()
		for ok && text == "" {
			text, ok = lines.next()
		}
		if !ok {
			break
		}
		if text != prefix && !strings.HasPrefix(text, prefix+" ") {
			lines.back()
			break
		}
		// Markdown sections can end in {#id} to set the HTML anchor for the section.
		// This is nicer than the default #TOC_1_2-style anchor.
		title := strings.TrimSpace(text[len(prefix):])
		id := ""
		if isMarkdown && strings.HasSuffix(title, "}") {
			j := strings.LastIndex(title, "{#")
			if j >= 0 {
				id = title[j+2 : len(title)-1]
				title = strings.TrimSpace(title[:j])
			}
		}
		section := Section{
			Number: append(slices.Clone(number), i),
			Title:  title,
			ID:     id,
		}
		text, ok = lines.nextNonEmpty()
		for ok && !lesserHeading(isHeading, text, prefix) {
			var e Elem
			r, _ := utf8.DecodeRuneInString(text)
			switch {
			case !isMarkdown && unicode.IsSpace(r):
				i := strings.IndexFunc(text, func(r rune) bool {
					return !unicode.IsSpace(r)
				})
				if i < 0 {
					break
				}
				indent := text[:i]
				var s []string
				for ok && (strings.HasPrefix(text, indent) || text == "") {
					if text != "" {
						text = text[i:]
					}
					s = append(s, text)
					text, ok = lines.next()
				}
				lines.back()
				pre := strings.Join(s, "\n")
				raw := pre
				pre = strings.Replace(pre, "\t", "    ", -1) // browsers treat tabs badly
				pre = strings.TrimRightFunc(pre, unicode.IsSpace)
				e = Text{Lines: []string{pre}, Pre: true, Raw: raw}
			case !isMarkdown && strings.HasPrefix(text, "- "):
				var b []string
				for {
					if strings.HasPrefix(text, "- ") {
						b = append(b, text[2:])
					} else if len(b) > 0 && strings.HasPrefix(text, " ") {
						b[len(b)-1] += "\n" + strings.TrimSpace(text)
					} else {
						break
					}
					if text, ok = lines.next(); !ok {
						break
					}
				}
				lines.back()
				e = List{Bullet: b}
			case isSpeakerNote(text):
				section.Notes = append(section.Notes, trimSpeakerNote(text))
			case strings.HasPrefix(text, prefix+prefix[:1]+" ") || text == prefix+prefix[:1]:
				lines.back()
				subsecs, err := parseSections(ctx, name, prefix+prefix[:1], lines, section.Number)
				if err != nil {
					return nil, err
				}
				for _, ss := range subsecs {
					section.Elem = append(section.Elem, ss)
				}
			case strings.HasPrefix(text, prefix+prefix[:1]):
				return nil, fmt.Errorf("%s:%d: badly nested section inside %s: %s", name, lines.line, prefix, text)
			case strings.HasPrefix(text, "."):
				args := strings.Fields(text)
				if args[0] == ".background" {
					section.Classes = append(section.Classes, "background")
					section.Styles = append(section.Styles, "background-image: url('"+args[1]+"')")
					break
				}
				parser := parsers[args[0]]
				if parser == nil {
					return nil, fmt.Errorf("%s:%d: unknown command %q", name, lines.line, text)
				}
				t, err := parser(ctx, name, lines.line, text)
				if err != nil {
					return nil, err
				}
				e = t

			case isMarkdown:
				// Collect Markdown lines, including blank lines and indented text.
				var block []string
				endLine, endBlock := lines.line-1, -1 // end is last non-empty line
				for ok {
					trim := strings.TrimSpace(text)
					if trim != "" {
						// Command breaks text block.
						// Section heading breaks text block in markdown.
						if text[0] == '.' || text[0] == '#' || isSpeakerNote(text) {
							break
						}
						if strings.HasPrefix(text, `\.`) { // Backslash escapes initial period.
							text = text[1:]
						}
						endLine, endBlock = lines.line, len(block)
					}
					block = append(block, text)
					text, ok = lines.next()
				}
				block = block[:endBlock+1]
				lines.line = endLine + 1
				if len(block) == 0 {
					break
				}

				// Replace all leading tabs with 4 spaces,
				// which render better in code blocks.
				// CommonMark defines that for parsing the structure of the file
				// a tab is equivalent to 4 spaces, so this change won't
				// affect the later parsing at all.
				// An alternative would be to apply this to code blocks after parsing,
				// at the same time that we update <a> targets, but that turns out
				// to be quite difficult to modify in the AST.
				for i, line := range block {
					if len(line) > 0 && line[0] == '\t' {
						short := strings.TrimLeft(line, "\t")
						line = strings.Repeat("    ", len(line)-len(short)) + short
						block[i] = line
					}
				}
				html, err := renderMarkdown([]byte(strings.Join(block, "\n")))
				if err != nil {
					return nil, err
				}
				e = HTML{HTML: html}

			default:
				// Collect text lines.
				var block []string
				for ok && strings.TrimSpace(text) != "" {
					// Command breaks text block.
					// Section heading breaks text block in markdown.
					if text[0] == '.' || isSpeakerNote(text) {
						lines.back()
						break
					}
					if strings.HasPrefix(text, `\.`) { // Backslash escapes initial period.
						text = text[1:]
					}
					block = append(block, text)
					text, ok = lines.next()
				}
				if len(block) == 0 {
					break
				}
				e = Text{Lines: block}
			}
			if e != nil {
				section.Elem = append(section.Elem, e)
			}
			text, ok = lines.nextNonEmpty()
		}
		if isHeading.MatchString(text) {
			lines.back()
		}
		sections = append(sections, section)
	}

	if len(sections) == 0 {
		return nil, fmt.Errorf("%s:%d: unexpected line: %s", name, lines.line+1, lines.text[lines.line])
	}
	return sections, nil
}

func parseHeader(doc *Doc, isMarkdown bool, lines *Lines) error {
	var ok bool
	// First non-empty line starts header.
	doc.Title, ok = lines.nextNonEmpty()
	if !ok {
		return errors.New("unexpected EOF; expected title")
	}
	if isMarkdown {
		doc.Title = strings.TrimSpace(strings.TrimPrefix(doc.Title, "#"))
	}

	for {
		text, ok := lines.next()
		if !ok {
			return errors.New("unexpected EOF")
		}
		if text == "" {
			break
		}
		if isSpeakerNote(text) {
			continue
		}
		if strings.HasPrefix(text, "Tags:") {
			tags := strings.Split(text[len("Tags:"):], ",")
			for i := range tags {
				tags[i] = strings.TrimSpace(tags[i])
			}
			doc.Tags = append(doc.Tags, tags...)
		} else if strings.HasPrefix(text, "Summary:") {
			doc.Summary = strings.TrimSpace(text[len("Summary:"):])
		} else if strings.HasPrefix(text, "OldURL:") {
			doc.OldURL = append(doc.OldURL, strings.TrimSpace(text[len("OldURL:"):]))
		} else if t, ok := parseTime(text); ok {
			doc.Time = t
		} else if doc.Subtitle == "" {
			doc.Subtitle = text
		} else {
			return fmt.Errorf("unexpected header line: %q", text)
		}
	}
	return nil
}

func parseAuthors(name, sectionPrefix string, lines *Lines) (authors []Author, err error) {
	// This grammar demarcates authors with blanks.

	// Skip blank lines.
	if _, ok := lines.nextNonEmpty(); !ok {
		return nil, errors.New("unexpected EOF")
	}
	lines.back()

	var a *Author
	for {
		text, ok := lines.next()
		if !ok {
			return nil, errors.New("unexpected EOF")
		}

		// If we find a section heading, we're done.
		if strings.HasPrefix(text, sectionPrefix) {
			lines.back()
			break
		}

		if isSpeakerNote(text) {
			continue
		}

		// If we encounter a blank we're done with this author.
		if a != nil && len(text) == 0 {
			authors = append(authors, *a)
			a = nil
			continue
		}
		if a == nil {
			a = new(Author)
		}

		// Parse the line. Those that
		// - begin with @ are twitter names,
		// - contain slashes are links, or
		// - contain an @ symbol are an email address.
		// The rest is just text.
		var el Elem
		switch {
		case strings.HasPrefix(text, "@"):
			el = parseAuthorURL(name, "http://twitter.com/"+text[1:])
		case strings.Contains(text, ":"):
			el = parseAuthorURL(name, text)
		case strings.Contains(text, "@"):
			el = parseAuthorURL(name, "mailto:"+text)
		}
		if l, ok := el.(Link); ok {
			l.Label = text
			el = l
		}
		if el == nil {
			el = Text{Lines: []string{text}}
		}
		a.Elem = append(a.Elem, el)
	}
	if a != nil {
		authors = append(authors, *a)
	}
	return authors, nil
}

func parseAuthorURL(name, text string) Elem {
	u, err := url.Parse(text)
	if err != nil {
		log.Printf("parsing %s author block: invalid URL %q: %v", name, text, err)
		return nil
	}
	return Link{URL: u}
}

func parseTime(text string) (t time.Time, ok bool) {
	t, err := time.Parse("15:04 2 Jan 2006", text)
	if err == nil {
		return t, true
	}
	t, err = time.Parse("2 Jan 2006", text)
	if err == nil {
		// at 11am UTC it is the same date everywhere
		t = t.Add(time.Hour * 11)
		return t, true
	}
	return time.Time{}, false
}

func isSpeakerNote(s string) bool {
	return strings.HasPrefix(s, ": ") || s == ":"
}

func trimSpeakerNote(s string) string {
	if s == ":" {
		return ""
	}
	return strings.TrimPrefix(s, ": ")
}

func renderMarkdown(input []byte) (template.HTML, error) {
	md := goldmark.New(goldmark.WithRendererOptions(html.WithUnsafe()))
	reader := text.NewReader(input)
	doc := md.Parser().Parse(reader)
	fixupMarkdown(doc)
	var b strings.Builder
	if err := md.Renderer().Render(&b, input, doc); err != nil {
		return "", err
	}
	return template.HTML(b.String()), nil
}

func fixupMarkdown(n ast.Node) {
	ast.Walk(n, func(n ast.Node, entering bool) (ast.WalkStatus, error) {
		if entering {
			switch n := n.(type) {
			case *ast.Link:
				n.SetAttributeString("target", []byte("_blank"))
				// https://developers.google.com/web/tools/lighthouse/audits/noopener
				n.SetAttributeString("rel", []byte("noopener"))
			}
		}
		return ast.WalkContinue, nil
	})
}


================================================
FILE: present/parse_test.go
================================================
// Copyright 2020 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"bytes"
	"fmt"
	"html/template"
	"os"
	"os/exec"
	"path/filepath"
	"runtime"
	"testing"
)

func TestTestdata(t *testing.T) {
	tmpl := template.Must(Template().Parse(testTmpl))
	filesP, err := filepath.Glob("testdata/*.p")
	if err != nil {
		t.Fatal(err)
	}
	filesMD, err := filepath.Glob("testdata/*.md")
	if err != nil {
		t.Fatal(err)
	}
	files := append(filesP, filesMD...)
	for _, file := range files {
		name := filepath.Base(file)
		if name == "README" {
			continue
		}
		t.Run(name, func(t *testing.T) {
			data, err := os.ReadFile(file)
			if err != nil {
				t.Fatalf("%s: %v", file, err)
			}
			marker := []byte("\n---\n")
			i := bytes.Index(data, marker)
			if i < 0 {
				t.Fatalf("%s: cannot find --- marker in input", file)
			}
			input, html := data[:i+1], data[i+len(marker):]
			doc, err := Parse(bytes.NewReader(input), name, 0)
			if err != nil {
				t.Fatalf("%s: %v", file, err)
			}
			var buf bytes.Buffer
			if err := doc.Render(&buf, tmpl); err != nil {
				t.Fatalf("%s: %v", file, err)
			}
			if !bytes.Equal(buf.Bytes(), html) {
				diffText, err := diff("present-test-", "want", html, "have", buf.Bytes())
				if err != nil {
					t.Fatalf("%s: diff: %v", file, err)
				}
				t.Errorf("%s: incorrect html:\n%s", file, diffText)
			}
		})
	}
}

func diff(prefix string, name1 string, b1 []byte, name2 string, b2 []byte) ([]byte, error) {
	f1, err := writeTempFile(prefix, b1)
	if err != nil {
		return nil, err
	}
	defer os.Remove(f1)

	f2, err := writeTempFile(prefix, b2)
	if err != nil {
		return nil, err
	}
	defer os.Remove(f2)

	cmd := "diff"
	if runtime.GOOS == "plan9" {
		cmd = "/bin/ape/diff"
	}

	data, err := exec.Command(cmd, "-u", f1, f2).Output()
	if len(data) > 0 {
		// diff exits with a non-zero status when the files don't match.
		// Ignore that failure as long as we get output.
		err = nil
	} else if exit, ok := err.(*exec.ExitError); ok && len(exit.Stderr) > 0 {
		err = fmt.Errorf("%w\nstderr:\n%s)", err, exit.Stderr)
	}

	data = bytes.Replace(data, []byte(f1), []byte(name1), -1)
	data = bytes.Replace(data, []byte(f2), []byte(name2), -1)

	return data, err
}

func writeTempFile(prefix string, data []byte) (string, error) {
	file, err := os.CreateTemp("", prefix)
	if err != nil {
		return "", err
	}
	_, err = file.Write(data)
	if err1 := file.Close(); err == nil {
		err = err1
	}
	if err != nil {
		os.Remove(file.Name())
		return "", err
	}
	return file.Name(), nil
}

var testTmpl = `
{{define "root" -}}
<h1>{{.Title}}</h1>
{{with .Subtitle}}<h2>{{.}}</h2>
{{end -}}
{{range .Authors}}<author>
{{range .Elem}}{{elem $.Template .}}{{end}}</author>
{{end -}}
{{range .Sections}}<section>{{elem $.Template .}}</section>
{{end -}}
{{end}}

{{define "newline"}}{{/* No automatic line break. Paragraphs are free-form. */}}
{{end}}

{{define "section"}}
{{if .Title}}<h2 id="TOC_{{.FormattedNumber}}">{{.Title}}</h2>
{{end -}}
{{range .Elem}}{{elem $.Template .}}{{end}}
{{- end}}

{{define "list" -}}
<ul>
{{range .Bullet -}}
<li>{{style .}}</li>
{{end -}}
</ul>
{{end}}

{{define "text" -}}
{{if .Pre -}}
<pre>{{range .Lines}}{{.}}{{end}}</pre>
{{else -}}
<p>{{range $i, $l := .Lines}}{{if $i}}{{template "newline"}}{{end}}{{style $l}}{{end}}</p>
{{end -}}
{{end}}

{{define "code" -}}
{{if .Play -}}
<div class="playground">{{.Text}}</div>
{{else -}}
<div class="code">{{.Text}}</div>
{{end -}}
{{end}}

{{define "image" -}}
<img src="{{.URL}}"{{with .Height}} height="{{.}}"{{end}}{{with .Width}} width="{{.}}"{{end}} alt="">
{{end}}

{{define "caption" -}}
<figcaption>{{style .Text}}</figcaption>
{{end}}

{{define "iframe" -}}
<iframe src="{{.URL}}"{{with .Height}} height="{{.}}"{{end}}{{with .Width}} width="{{.}}"{{end}}></iframe>
{{end}}

{{define "link" -}}
<p class="link"><a href="{{.URL}}">{{style .Label}}</a></p>
{{end}}

{{define "html" -}}{{.HTML}}{{end}}
`


================================================
FILE: present/style.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"bytes"
	"html"
	"html/template"
	"strings"
	"unicode"
	"unicode/utf8"
)

/*
	Fonts are demarcated by an initial and final char bracketing a
	space-delimited word, plus possibly some terminal punctuation.
	The chars are
		_ for italic
		* for bold
		` (back quote) for fixed width.
	Inner appearances of the char become spaces. For instance,
		_this_is_italic_!
	becomes
		<i>this is italic</i>!
*/

func init() {
	funcs["style"] = Style
}

// Style returns s with HTML entities escaped and font indicators turned into
// HTML font tags.
func Style(s string) template.HTML {
	return template.HTML(font(html.EscapeString(s)))
}

// font returns s with font indicators turned into HTML font tags.
func font(s string) string {
	if !strings.ContainsAny(s, "[`_*") {
		return s
	}
	words := split(s)
	var b bytes.Buffer
Word:
	for w, word := range words {
		if len(word) < 2 {
			continue Word
		}
		if link, _ := parseInlineLink(word); link != "" {
			words[w] = link
			continue Word
		}
		const marker = "_*`"
		// Initial punctuation is OK but must be peeled off.
		first := strings.IndexAny(word, marker)
		if first == -1 {
			continue Word
		}
		// Opening marker must be at the beginning of the token or else preceded by punctuation.
		if first != 0 {
			r, _ := utf8.DecodeLastRuneInString(word[:first])
			if !unicode.IsPunct(r) {
				continue Word
			}
		}
		open, word := word[:first], word[first:]
		char := word[0] // ASCII is OK.
		close := ""
		switch char {
		default:
			continue Word
		case '_':
			open += "<i>"
			close = "</i>"
		case '*':
			open += "<b>"
			close = "</b>"
		case '`':
			open += "<code>"
			close = "</code>"
		}
		// Closing marker must be at the end of the token or else followed by punctuation.
		last := strings.LastIndex(word, word[:1])
		if last == 0 {
			continue Word
		}
		if last+1 != len(word) {
			r, _ := utf8.DecodeRuneInString(word[last+1:])
			if !unicode.IsPunct(r) {
				continue Word
			}
		}
		head, tail := word[:last+1], word[last+1:]
		b.Reset()
		b.WriteString(open)
		var wid int
		for i := 1; i < len(head)-1; i += wid {
			var r rune
			r, wid = utf8.DecodeRuneInString(head[i:])
			if r != rune(char) {
				// Ordinary character.
				b.WriteRune(r)
				continue
			}
			if head[i+1] != char {
				// Inner char becomes space.
				b.WriteRune(' ')
				continue
			}
			// Doubled char becomes real char.
			// Not worth worrying about "_x__".
			b.WriteByte(char)
			wid++ // Consumed two chars, both ASCII.
		}
		b.WriteString(close) // Write closing tag.
		b.WriteString(tail)  // Restore trailing punctuation.
		words[w] = b.String()
	}
	return strings.Join(words, "")
}

// split is like strings.Fields but also returns the runs of spaces
// and treats inline links as distinct words.
func split(s string) []string {
	var (
		words = make([]string, 0, 10)
		start = 0
	)

	// appendWord appends the string s[start:end] to the words slice.
	// If the word contains the beginning of a link, the non-link portion
	// of the word and the entire link are appended as separate words,
	// and the start index is advanced to the end of the link.
	appendWord := func(end int) {
		if j := strings.Index(s[start:end], "[["); j > -1 {
			if _, l := parseInlineLink(s[start+j:]); l > 0 {
				// Append portion before link, if any.
				if j > 0 {
					words = append(words, s[start:start+j])
				}
				// Append link itself.
				words = append(words, s[start+j:start+j+l])
				// Advance start index to end of link.
				start = start + j + l
				return
			}
		}
		// No link; just add the word.
		words = append(words, s[start:end])
		start = end
	}

	wasSpace := false
	for i, r := range s {
		isSpace := unicode.IsSpace(r)
		if i > start && isSpace != wasSpace {
			appendWord(i)
		}
		wasSpace = isSpace
	}
	for start < len(s) {
		appendWord(len(s))
	}
	return words
}


================================================
FILE: present/style_test.go
================================================
// Copyright 2012 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"reflect"
	"testing"
)

func TestSplit(t *testing.T) {
	var tests = []struct {
		in  string
		out []string
	}{
		{"", []string{}},
		{" ", []string{" "}},
		{"abc", []string{"abc"}},
		{"abc def", []string{"abc", " ", "def"}},
		{"abc def ", []string{"abc", " ", "def", " "}},
		{"hey [[http://golang.org][Gophers]] around",
			[]string{"hey", " ", "[[http://golang.org][Gophers]]", " ", "around"}},
		{"A [[http://golang.org/doc][two words]] link",
			[]string{"A", " ", "[[http://golang.org/doc][two words]]", " ", "link"}},
		{"Visit [[http://golang.org/doc]] now",
			[]string{"Visit", " ", "[[http://golang.org/doc]]", " ", "now"}},
		{"not [[http://golang.org/doc][a [[link]] ]] around",
			[]string{"not", " ", "[[http://golang.org/doc][a [[link]]", " ", "]]", " ", "around"}},
		{"[[http://golang.org][foo bar]]",
			[]string{"[[http://golang.org][foo bar]]"}},
		{"ends with [[http://golang.org][link]]",
			[]string{"ends", " ", "with", " ", "[[http://golang.org][link]]"}},
		{"my talk ([[http://talks.golang.org/][slides here]])",
			[]string{"my", " ", "talk", " ", "(", "[[http://talks.golang.org/][slides here]]", ")"}},
	}
	for _, test := range tests {
		out := split(test.in)
		if !reflect.DeepEqual(out, test.out) {
			t.Errorf("split(%q):\ngot\t%q\nwant\t%q", test.in, out, test.out)
		}
	}
}

func TestFont(t *testing.T) {
	var tests = []struct {
		in  string
		out string
	}{
		{"", ""},
		{" ", " "},
		{"\tx", "\tx"},
		{"_a_", "<i>a</i>"},
		{"*a*", "<b>a</b>"},
		{"`a`", "<code>a</code>"},
		{"_a_b_", "<i>a b</i>"},
		{"_a__b_", "<i>a_b</i>"},
		{"_a___b_", "<i>a_ b</i>"},
		{"*a**b*?", "<b>a*b</b>?"},
		{"_a_<>_b_.", "<i>a <> b</i>."},
		{"(_a_)", "(<i>a</i>)"},
		{"((_a_), _b_, _c_).", "((<i>a</i>), <i>b</i>, <i>c</i>)."},
		{"(_a)", "(_a)"},
		{"(_a)", "(_a)"},
		{"_Why_use_scoped__ptr_? Use plain ***ptr* instead.", "<i>Why use scoped_ptr</i>? Use plain <b>*ptr</b> instead."},
		{"_hey_ [[http://golang.org][*Gophers*]] *around*",
			`<i>hey</i> <a href="http://golang.org" target="_blank"><b>Gophers</b></a> <b>around</b>`},
		{"_hey_ [[http://golang.org][so _many_ *Gophers*]] *around*",
			`<i>hey</i> <a href="http://golang.org" target="_blank">so <i>many</i> <b>Gophers</b></a> <b>around</b>`},
		{"Visit [[http://golang.org]] now",
			`Visit <a href="http://golang.org" target="_blank">golang.org</a> now`},
		{"my talk ([[http://talks.golang.org/][slides here]])",
			`my talk (<a href="http://talks.golang.org/" target="_blank">slides here</a>)`},
		{"Markup—_especially_italic_text_—can easily be overused.",
			`Markup—<i>especially italic text</i>—can easily be overused.`},
		{"`go`get`'s codebase", // ascii U+0027 ' before s
			`<code>go get</code>'s codebase`},
		{"`go`get`’s codebase", // unicode right single quote U+2019 ’ before s
			`<code>go get</code>’s codebase`},
		{"a_variable_name",
			`a_variable_name`},
	}
	for _, test := range tests {
		out := font(test.in)
		if out != test.out {
			t.Errorf("font(%q):\ngot\t%q\nwant\t%q", test.in, out, test.out)
		}
	}
}

func TestStyle(t *testing.T) {
	var tests = []struct {
		in  string
		out string
	}{
		{"", ""},
		{" ", " "},
		{"\tx", "\tx"},
		{"_a_", "<i>a</i>"},
		{"*a*", "<b>a</b>"},
		{"`a`", "<code>a</code>"},
		{"_a_b_", "<i>a b</i>"},
		{"_a__b_", "<i>a_b</i>"},
		{"_a___b_", "<i>a_ b</i>"},
		{"*a**b*?", "<b>a*b</b>?"},
		{"_a_<>_b_.", "<i>a &lt;&gt; b</i>."},
		{"(_a_<>_b_)", "(<i>a &lt;&gt; b</i>)"},
		{"((_a_), _b_, _c_).", "((<i>a</i>), <i>b</i>, <i>c</i>)."},
		{"(_a)", "(_a)"},
	}
	for _, test := range tests {
		out := string(Style(test.in))
		if out != test.out {
			t.Errorf("style(%q):\ngot\t%q\nwant\t%q", test.in, out, test.out)
		}
	}
}

func ExampleStyle() {
	const s = "*Gophers* are _clearly_ > *cats*!"
	fmt.Println(Style(s))
	// Output: <b>Gophers</b> are <i>clearly</i> &gt; <b>cats</b>!
}


================================================
FILE: present/testdata/README
================================================
This directory contains test data for present's TestTestdata.
Each file named *.p or *.md is expected to contain a present
article, then a --- line, then the HTML output for that article.

By convention, testdata files with a .p extension use legacy present
syntax, while testdata file with a .md extension use Markdown.
This is only a convention: the Markdown syntax must still begi
with "# " to be recognized as Markdown by the present parser.

Other files in this directory are supporting files for the articles.


================================================
FILE: present/testdata/basic.md
================================================
# Title
Subtitle

Name

## Heading

Text
on two lines.

More text.

---
<h1>Title</h1>
<h2>Subtitle</h2>
<author>
<p>Name</p>
</author>
<section>
<h2 id="TOC_1.">Heading</h2>
<p>Text
on two lines.</p>
<p>More text.</p>
</section>


================================================
FILE: present/testdata/basic.p
================================================
Title
Subtitle

Name

* Heading

Text
on two lines.

More text.

---
<h1>Title</h1>
<h2>Subtitle</h2>
<author>
<p>Name</p>
</author>
<section>
<h2 id="TOC_1.">Heading</h2>
<p>Text
on two lines.</p>
<p>More text.</p>
</section>


================================================
FILE: present/testdata/code.md
================================================
# Code

##

Code:

.code testdata/code.txt

Snippet:

.code testdata/code.txt /Snippet/

Highlight:

.code testdata/code.txt HL1

---
<h1>Code</h1>
<section>
<p>Code:</p>
<div class="code">
<pre><span num="1">code file</span>
<span num="2">Snippet</span>
<span num="3">important</span>
</pre>
</div>
<p>Snippet:</p>
<div class="code">
<pre><span num="2">Snippet</span>
</pre>
</div>
<p>Highlight:</p>
<div class="code">
<pre><span num="1">code file</span>
<span num="2">Snippet</span>
<span num="3"><b>important</b></span>
</pre>
</div>
</section>


================================================
FILE: present/testdata/code.p
================================================
Code

*

Code:

.code testdata/code.txt

Snippet:

.code testdata/code.txt /Snippet/

Highlight:

.code testdata/code.txt HL1

---
<h1>Code</h1>
<section>
<p>Code:</p>
<div class="code">
<pre><span num="1">code file</span>
<span num="2">Snippet</span>
<span num="3">important</span>
</pre>
</div>
<p>Snippet:</p>
<div class="code">
<pre><span num="2">Snippet</span>
</pre>
</div>
<p>Highlight:</p>
<div class="code">
<pre><span num="1">code file</span>
<span num="2">Snippet</span>
<span num="3"><b>important</b></span>
</pre>
</div>
</section>


================================================
FILE: present/testdata/code.txt
================================================
code file
Snippet
important // HL1


================================================
FILE: present/testdata/list.md
================================================
# List

##

- Item 1
 on two lines.
- Item 2.
- Item 3.

- Item 4 in list despite preceding blank line.
- Item 5.

---
<h1>List</h1>
<section>
<ul>
<li>
<p>Item 1
on two lines.</p>
</li>
<li>
<p>Item 2.</p>
</li>
<li>
<p>Item 3.</p>
</li>
<li>
<p>Item 4 in list despite preceding blank line.</p>
</li>
<li>
<p>Item 5.</p>
</li>
</ul>
</section>


================================================
FILE: present/testdata/list.p
================================================
List

*

- Item 1
 on two lines.
- Item 2.
- Item 3.

- Item 1 in new list.
- Item 2.

---
<h1>List</h1>
<section>
<ul>
<li>Item 1
on two lines.</li>
<li>Item 2.</li>
<li>Item 3.</li>
</ul>
<ul>
<li>Item 1 in new list.</li>
<li>Item 2.</li>
</ul>
</section>


================================================
FILE: present/testdata/media.html
================================================
<!-- media.html -->


================================================
FILE: present/testdata/media.md
================================================
# Media

##

.image gopher.jpg _ 100
.caption A gopher.

.iframe https://golang.org/

.link https://golang.org/ The Gopher's home.

.html testdata/media.html

---
<h1>Media</h1>
<section>
<img src="gopher.jpg" width="100" alt="">
<figcaption>A gopher.</figcaption>
<iframe src="https://golang.org/"></iframe>
<p class="link"><a href="https://golang.org/">The Gopher&#39;s home.</a></p>
<!-- media.html -->
</section>


================================================
FILE: present/testdata/media.p
================================================
Media

*

The Gopher
.image gopher.jpg _ 100
.caption A gopher.

.iframe https://golang.org/

.link https://golang.org/ The Gopher's home.

.html testdata/media.html

---
<h1>Media</h1>
<section>
<p>The Gopher</p>
<img src="gopher.jpg" width="100" alt="">
<figcaption>A gopher.</figcaption>
<iframe src="https://golang.org/"></iframe>
<p class="link"><a href="https://golang.org/">The Gopher&#39;s home.</a></p>
<!-- media.html -->
</section>


================================================
FILE: present/testdata/pre.md
================================================
# Pre

##

Pre with tab:

	code block
	on two lines

Text with space:

 now a text block
 on two lines

Pre with blank line:

	before

	after

EOF

---
<h1>Pre</h1>
<section>
<p>Pre with tab:</p>
<pre><code>code block
on two lines
</code></pre>
<p>Text with space:</p>
<p>now a text block
on two lines</p>
<p>Pre with blank line:</p>
<pre><code>before

after
</code></pre>
<p>EOF</p>
</section>


================================================
FILE: present/testdata/pre.p
================================================
Pre

*

Pre with tab:

	code block
	on two lines

Pre with space:

 code block
 on two lines

Pre with blank line:

	before

	after

EOF

---
<h1>Pre</h1>
<section>
<p>Pre with tab:</p>
<pre>code block
on two lines</pre>
<p>Pre with space:</p>
<pre>code block
on two lines</pre>
<p>Pre with blank line:</p>
<pre>before

after</pre>
<p>EOF</p>
</section>


================================================
FILE: present/video.go
================================================
// Copyright 2016 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package present

import (
	"fmt"
	"strings"
)

func init() {
	Register("video", parseVideo)
}

type Video struct {
	Cmd        string // original command from present source
	URL        string
	SourceType string
	Width      int
	Height     int
}

func (v Video) PresentCmd() string   { return v.Cmd }
func (v Video) TemplateName() string { return "video" }

func parseVideo(ctx *Context, fileName string, lineno int, text string) (Elem, error) {
	args := strings.Fields(text)
	if len(args) < 3 {
		return nil, fmt.Errorf("incorrect video invocation: %q", text)
	}
	vid := Video{Cmd: text, URL: args[1], SourceType: args[2]}
	a, err := parseArgs(fileName, lineno, args[3:])
	if err != nil {
		return nil, err
	}
	switch len(a) {
	case 0:
		// no size parameters
	case 2:
		// If a parameter is empty (underscore) or invalid
		// leave the field set to zero. The "video" action
		// template will then omit that vid tag attribute and
		// the browser will calculate the value to preserve
		// the aspect ratio.
		if v, ok := a[0].(int); ok {
			vid.Height = v
		}
		if v, ok := a[1].(int); ok {
			vid.Width = v
		}
	default:
		return nil, fmt.Errorf("incorrect video invocation: %q", text)
	}
	return vid, nil
}


================================================
FILE: refactor/README
================================================
golang.org/x/tools/refactor: libraries for refactoring tools.


================================================
FILE: refactor/eg/eg.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package eg implements the example-based refactoring tool whose
// command-line is defined in golang.org/x/tools/cmd/eg.
package eg // import "golang.org/x/tools/refactor/eg"

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/format"
	"go/printer"
	"go/token"
	"go/types"
	"maps"
	"os"
)

const Help = `
This tool implements example-based refactoring of expressions.

The transformation is specified as a Go file defining two functions,
'before' and 'after', of identical types.  Each function body consists
of a single statement: either a return statement with a single
(possibly multi-valued) expression, or an expression statement.  The
'before' expression specifies a pattern and the 'after' expression its
replacement.

	package P
 	import ( "errors"; "fmt" )
 	func before(s string) error { return fmt.Errorf("%s", s) }
 	func after(s string)  error { return errors.New(s) }

The expression statement form is useful when the expression has no
result, for example:

 	func before(msg string) { log.Fatalf("%s", msg) }
 	func after(msg string)  { log.Fatal(msg) }

The parameters of both functions are wildcards that may match any
expression assignable to that type.  If the pattern contains multiple
occurrences of the same parameter, each must match the same expression
in the input for the pattern to match.  If the replacement contains
multiple occurrences of the same parameter, the expression will be
duplicated, possibly changing the side-effects.

The tool analyses all Go code in the packages specified by the
arguments, replacing all occurrences of the pattern with the
substitution.

So, the transform above would change this input:
	err := fmt.Errorf("%s", "error: " + msg)
to this output:
	err := errors.New("error: " + msg)

Identifiers, including qualified identifiers (p.X) are considered to
match only if they denote the same object.  This allows correct
matching even in the presence of dot imports, named imports and
locally shadowed package names in the input program.

Matching of type syntax is semantic, not syntactic: type syntax in the
pattern matches type syntax in the input if the types are identical.
Thus, func(x int) matches func(y int).

This tool was inspired by other example-based refactoring tools,
'gofmt -r' for Go and Refaster for Java.


LIMITATIONS
===========

EXPRESSIVENESS

Only refactorings that replace one expression with another, regardless
of the expression's context, may be expressed.  Refactoring arbitrary
statements (or sequences of statements) is a less well-defined problem
and is less amenable to this approach.

A pattern that contains a function literal (and hence statements)
never matches.

There is no way to generalize over related types, e.g. to express that
a wildcard may have any integer type, for example.

It is not possible to replace an expression by one of a different
type, even in contexts where this is legal, such as x in fmt.Print(x).

The struct literals T{x} and T{K: x} cannot both be matched by a single
template.


SAFETY

Verifying that a transformation does not introduce type errors is very
complex in the general case.  An innocuous-looking replacement of one
constant by another (e.g. 1 to 2) may cause type errors relating to
array types and indices, for example.  The tool performs only very
superficial checks of type preservation.


IMPORTS

Although the matching algorithm is fully aware of scoping rules, the
replacement algorithm is not, so the replacement code may contain
incorrect identifier syntax for imported objects if there are dot
imports, named imports or locally shadowed package names in the input
program.

Imports are added as needed, but they are not removed as needed.
Run 'goimports' on the modified file for now.

Dot imports are forbidden in the template.


TIPS
====

Sometimes a little creativity is required to implement the desired
migration.  This section lists a few tips and tricks.

To remove the final parameter from a function, temporarily change the
function signature so that the final parameter is variadic, as this
allows legal calls both with and without the argument.  Then use eg to
remove the final argument from all callers, and remove the variadic
parameter by hand.  The reverse process can be used to add a final
parameter.

To add or remove parameters other than the final one, you must do it in
stages: (1) declare a variant function f' with a different name and the
desired parameters; (2) use eg to transform calls to f into calls to f',
changing the arguments as needed; (3) change the declaration of f to
match f'; (4) use eg to rename f' to f in all calls; (5) delete f'.
`

// TODO(adonovan): expand upon the above documentation as an HTML page.

// A Transformer represents a single example-based transformation.
type Transformer struct {
	fset           *token.FileSet
	verbose        bool
	info           *types.Info // combined type info for template/input/output ASTs
	seenInfos      map[*types.Info]bool
	wildcards      map[*types.Var]bool                // set of parameters in func before()
	env            map[string]ast.Expr                // maps parameter name to wildcard binding
	importedObjs   map[types.Object]*ast.SelectorExpr // objects imported by after().
	before, after  ast.Expr
	afterStmts     []ast.Stmt
	allowWildcards bool

	// Working state of Transform():
	nsubsts    int            // number of substitutions made
	currentPkg *types.Package // package of current call
}

// NewTransformer returns a transformer based on the specified template,
// a single-file package containing "before" and "after" functions as
// described in the package documentation.
// tmplInfo is the type information for tmplFile.
func NewTransformer(fset *token.FileSet, tmplPkg *types.Package, tmplFile *ast.File, tmplInfo *types.Info, verbose bool) (*Transformer, error) {
	// These maps are required by types.Info.TypeOf.
	if tmplInfo.Types == nil || tmplInfo.Defs == nil || tmplInfo.Uses == nil {
		return nil, errors.New("eg.NewTransformer: types.Info argument missing one of Types, Defs or Uses")
	}
	// Check the template.
	beforeSig := funcSig(tmplPkg, "before")
	if beforeSig == nil {
		return nil, fmt.Errorf("no 'before' func found in template")
	}
	afterSig := funcSig(tmplPkg, "after")
	if afterSig == nil {
		return nil, fmt.Errorf("no 'after' func found in template")
	}

	// TODO(adonovan): should we also check the names of the params match?
	if !types.Identical(afterSig, beforeSig) {
		return nil, fmt.Errorf("before %s and after %s functions have different signatures",
			beforeSig, afterSig)
	}

	for _, imp := range tmplFile.Imports {
		if imp.Name != nil && imp.Name.Name == "." {
			// Dot imports are currently forbidden.  We
			// make the simplifying assumption that all
			// imports are regular, without local renames.
			return nil, fmt.Errorf("dot-import (of %s) in template", imp.Path.Value)
		}
	}
	var beforeDecl, afterDecl *ast.FuncDecl
	for _, decl := range tmplFile.Decls {
		if decl, ok := decl.(*ast.FuncDecl); ok {
			switch decl.Name.Name {
			case "before":
				beforeDecl = decl
			case "after":
				afterDecl = decl
			}
		}
	}

	before, err := soleExpr(beforeDecl)
	if err != nil {
		return nil, fmt.Errorf("before: %s", err)
	}
	afterStmts, after, err := stmtAndExpr(afterDecl)
	if err != nil {
		return nil, fmt.Errorf("after: %s", err)
	}

	wildcards := make(map[*types.Var]bool)
	for v := range beforeSig.Params().Variables() {
		wildcards[v] = true
	}

	// checkExprTypes returns an error if Tb (type of before()) is not
	// safe to replace with Ta (type of after()).
	//
	// Only superficial checks are performed, and they may result in both
	// false positives and negatives.
	//
	// Ideally, we would only require that the replacement be assignable
	// to the context of a specific pattern occurrence, but the type
	// checker doesn't record that information and it's complex to deduce.
	// A Go type cannot capture all the constraints of a given expression
	// context, which may include the size, constness, signedness,
	// namedness or constructor of its type, and even the specific value
	// of the replacement.  (Consider the rule that array literal keys
	// must be unique.)  So we cannot hope to prove the safety of a
	// transformation in general.
	Tb := tmplInfo.TypeOf(before)
	Ta := tmplInfo.TypeOf(after)
	if types.AssignableTo(Tb, Ta) {
		// safe: replacement is assignable to pattern.
	} else if tuple, ok := Tb.(*types.Tuple); ok && tuple.Len() == 0 {
		// safe: pattern has void type (must appear in an ExprStmt).
	} else {
		return nil, fmt.Errorf("%s is not a safe replacement for %s", Ta, Tb)
	}

	tr := &Transformer{
		fset:           fset,
		verbose:        verbose,
		wildcards:      wildcards,
		allowWildcards: true,
		seenInfos:      make(map[*types.Info]bool),
		importedObjs:   make(map[types.Object]*ast.SelectorExpr),
		before:         before,
		after:          after,
		afterStmts:     afterStmts,
	}

	// Combine type info from the template and input packages, and
	// type info for the synthesized ASTs too.  This saves us
	// having to book-keep where each ast.Node originated as we
	// construct the resulting hybrid AST.
	tr.info = &types.Info{
		Types:      make(map[ast.Expr]types.TypeAndValue),
		Defs:       make(map[*ast.Ident]types.Object),
		Uses:       make(map[*ast.Ident]types.Object),
		Selections: make(map[*ast.SelectorExpr]*types.Selection),
	}
	mergeTypeInfo(tr.info, tmplInfo)

	// Compute set of imported objects required by after().
	// TODO(adonovan): reject dot-imports in pattern
	ast.Inspect(after, func(n ast.Node) bool {
		if n, ok := n.(*ast.SelectorExpr); ok {
			if _, ok := tr.info.Selections[n]; !ok {
				// qualified ident
				obj := tr.info.Uses[n.Sel]
				tr.importedObjs[obj] = n
				return false // prune
			}
		}
		return true // recur
	})

	return tr, nil
}

// WriteAST is a convenience function that writes AST f to the specified file.
func WriteAST(fset *token.FileSet, filename string, f *ast.File) (err error) {
	fh, err := os.Create(filename)
	if err != nil {
		return err
	}

	defer func() {
		if err2 := fh.Close(); err != nil {
			err = err2 // prefer earlier error
		}
	}()
	return format.Node(fh, fset, f)
}

// -- utilities --------------------------------------------------------

// funcSig returns the signature of the specified package-level function.
func funcSig(pkg *types.Package, name string) *types.Signature {
	if f, ok := pkg.Scope().Lookup(name).(*types.Func); ok {
		return f.Type().(*types.Signature)
	}
	return nil
}

// soleExpr returns the sole expression in the before/after template function.
func soleExpr(fn *ast.FuncDecl) (ast.Expr, error) {
	if fn.Body == nil {
		return nil, fmt.Errorf("no body")
	}
	if len(fn.Body.List) != 1 {
		return nil, fmt.Errorf("must contain a single statement")
	}
	switch stmt := fn.Body.List[0].(type) {
	case *ast.ReturnStmt:
		if len(stmt.Results) != 1 {
			return nil, fmt.Errorf("return statement must have a single operand")
		}
		return stmt.Results[0], nil

	case *ast.ExprStmt:
		return stmt.X, nil
	}

	return nil, fmt.Errorf("must contain a single return or expression statement")
}

// stmtAndExpr returns the expression in the last return statement as well as the preceding lines.
func stmtAndExpr(fn *ast.FuncDecl) ([]ast.Stmt, ast.Expr, error) {
	if fn.Body == nil {
		return nil, nil, fmt.Errorf("no body")
	}

	n := len(fn.Body.List)
	if n == 0 {
		return nil, nil, fmt.Errorf("must contain at least one statement")
	}

	stmts, last := fn.Body.List[:n-1], fn.Body.List[n-1]

	switch last := last.(type) {
	case *ast.ReturnStmt:
		if len(last.Results) != 1 {
			return nil, nil, fmt.Errorf("return statement must have a single operand")
		}
		return stmts, last.Results[0], nil

	case *ast.ExprStmt:
		return stmts, last.X, nil
	}

	return nil, nil, fmt.Errorf("must end with a single return or expression statement")
}

// mergeTypeInfo adds type info from src to dst.
func mergeTypeInfo(dst, src *types.Info) {
	maps.Copy(dst.Types, src.Types)
	maps.Copy(dst.Defs, src.Defs)
	maps.Copy(dst.Uses, src.Uses)
	maps.Copy(dst.Selections, src.Selections)
}

// (debugging only)
func astString(fset *token.FileSet, n ast.Node) string {
	var buf bytes.Buffer
	printer.Fprint(&buf, fset, n)
	return buf.String()
}


================================================
FILE: refactor/eg/eg_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// No testdata on Android.

//go:build !android

package eg_test

import (
	"bytes"
	"flag"
	"fmt"
	"go/constant"
	"go/format"
	"go/types"
	"os"
	"path/filepath"
	"runtime"
	"strings"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/tools/go/packages"
	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/internal/testfiles"
	"golang.org/x/tools/refactor/eg"
	"golang.org/x/tools/txtar"
)

// TODO(adonovan): more tests:
// - of command-line tool
// - of all parts of syntax
// - of applying a template to a package it imports:
//   the replacement syntax should use unqualified names for its objects.

var (
	updateFlag  = flag.Bool("update", false, "update the golden files")
	verboseFlag = flag.Bool("verbose", false, "show matcher information")
)

func Test(t *testing.T) {
	testenv.NeedsGoPackages(t)

	switch runtime.GOOS {
	case "windows":
		t.Skipf("skipping test on %q (no /usr/bin/diff)", runtime.GOOS)
	}

	// Each txtar defines a package example.com/template and zero
	// or more input packages example.com/in/... on which to apply
	// it. The outputs are compared with the corresponding files
	// in example.com/out/...
	for _, filename := range []string{
		"testdata/a.txtar",
		"testdata/b.txtar",
		"testdata/c.txtar",
		"testdata/d.txtar",
		"testdata/e.txtar",
		"testdata/f.txtar",
		"testdata/g.txtar",
		"testdata/h.txtar",
		"testdata/i.txtar",
		"testdata/j.txtar",
		"testdata/bad_type.txtar",
		"testdata/no_before.txtar",
		"testdata/no_after_return.txtar",
		"testdata/type_mismatch.txtar",
		"testdata/expr_type_mismatch.txtar",
	} {
		t.Run(filename, func(t *testing.T) {
			// Extract and load packages from test archive.
			dir := testfiles.ExtractTxtarFileToTmp(t, filename)
			cfg := packages.Config{
				Mode: packages.LoadAllSyntax,
				Dir:  dir,
			}
			pkgs, err := packages.Load(&cfg, "example.com/template", "example.com/in/...")
			if err != nil {
				t.Fatal(err)
			}
			if packages.PrintErrors(pkgs) > 0 {
				t.Fatal("Load: there were errors")
			}

			// Find and compile the template.
			var template *packages.Package
			var inputs []*packages.Package
			for _, pkg := range pkgs {
				if pkg.Types.Name() == "template" {
					template = pkg
				} else {
					inputs = append(inputs, pkg)
				}
			}
			if template == nil {
				t.Fatal("no template package")
			}
			shouldFail, _ := template.Types.Scope().Lookup("shouldFail").(*types.Const)
			xform, err := eg.NewTransformer(template.Fset, template.Types, template.Syntax[0], template.TypesInfo, *verboseFlag)
			if err != nil {
				if shouldFail == nil {
					t.Errorf("NewTransformer(%s): %s", filename, err)
				} else if want := constant.StringVal(shouldFail.Val()); !strings.Contains(normalizeAny(err.Error()), want) {
					t.Errorf("NewTransformer(%s): got error %q, want error %q", filename, err, want)
				}
			} else if shouldFail != nil {
				t.Errorf("NewTransformer(%s) succeeded unexpectedly; want error %q",
					filename, shouldFail.Val())
			}

			// Apply template to each input package.
			updated := make(map[string][]byte)
			for _, pkg := range inputs {
				for _, file := range pkg.Syntax {
					filename, err := filepath.Rel(dir, pkg.Fset.File(file.FileStart).Name())
					if err != nil {
						t.Fatalf("can't relativize filename: %v", err)
					}

					// Apply the transform and reformat.
					n := xform.Transform(pkg.TypesInfo, pkg.Types, file)
					if n == 0 {
						t.Fatalf("%s: no replacements", filename)
					}
					var got []byte
					{
						var out bytes.Buffer
						format.Node(&out, pkg.Fset, file) // ignore error
						got = out.Bytes()
					}

					// Compare formatted output with out/<filename>
					// Errors here are not fatal, so we can proceed to -update.
					outfile := strings.Replace(filename, "in", "out", 1)
					updated[outfile] = got
					want, err := os.ReadFile(filepath.Join(dir, outfile))
					if err != nil {
						t.Errorf("can't read output file: %v", err)
					} else if diff := cmp.Diff(want, got); diff != "" {
						t.Errorf("Unexpected output:\n%s\n\ngot %s:\n%s\n\nwant %s:\n%s",
							diff,
							filename, got, outfile, want)
					}
				}
			}

			// -update: replace the .txtar.
			if *updateFlag {
				ar, err := txtar.ParseFile(filename)
				if err != nil {
					t.Fatal(err)
				}

				var new bytes.Buffer
				new.Write(ar.Comment)
				for _, file := range ar.Files {
					data, ok := updated[file.Name]
					if !ok {
						data = file.Data
					}
					fmt.Fprintf(&new, "-- %s --\n%s", file.Name, data)
				}
				t.Logf("Updating %s...", filename)
				os.Remove(filename + ".bak")         // ignore error
				os.Rename(filename, filename+".bak") // ignore error
				if err := os.WriteFile(filename, new.Bytes(), 0666); err != nil {
					t.Fatal(err)
				}
			}
		})
	}
}

// normalizeAny replaces occurrences of interface{} with any, for consistent
// output.
func normalizeAny(s string) string {
	return strings.ReplaceAll(s, "interface{}", "any")
}


================================================
FILE: refactor/eg/match.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package eg

import (
	"fmt"
	"go/ast"
	"go/constant"
	"go/token"
	"go/types"
	"log"
	"os"
	"reflect"
)

// matchExpr reports whether pattern x matches y.
//
// If tr.allowWildcards, Idents in x that refer to parameters are
// treated as wildcards, and match any y that is assignable to the
// parameter type; matchExpr records this correspondence in tr.env.
// Otherwise, matchExpr simply reports whether the two trees are
// equivalent.
//
// A wildcard appearing more than once in the pattern must
// consistently match the same tree.
func (tr *Transformer) matchExpr(x, y ast.Expr) bool {
	if x == nil && y == nil {
		return true
	}
	if x == nil || y == nil {
		return false
	}
	x = ast.Unparen(x)
	y = ast.Unparen(y)

	// Is x a wildcard?  (a reference to a 'before' parameter)
	if xobj, ok := tr.wildcardObj(x); ok {
		return tr.matchWildcard(xobj, y)
	}

	// Object identifiers (including pkg-qualified ones)
	// are handled semantically, not syntactically.
	xobj := isRef(x, tr.info)
	yobj := isRef(y, tr.info)
	if xobj != nil {
		return xobj == yobj
	}
	if yobj != nil {
		return false
	}

	// TODO(adonovan): audit: we cannot assume these ast.Exprs
	// contain non-nil pointers.  e.g. ImportSpec.Name may be a
	// nil *ast.Ident.

	if reflect.TypeOf(x) != reflect.TypeOf(y) {
		return false
	}
	switch x := x.(type) {
	case *ast.Ident:
		log.Fatalf("unexpected Ident: %s", astString(tr.fset, x))

	case *ast.BasicLit:
		y := y.(*ast.BasicLit)
		xval := constant.MakeFromLiteral(x.Value, x.Kind, 0)
		yval := constant.MakeFromLiteral(y.Value, y.Kind, 0)
		return constant.Compare(xval, token.EQL, yval)

	case *ast.FuncLit:
		// func literals (and thus statement syntax) never match.
		return false

	case *ast.CompositeLit:
		y := y.(*ast.CompositeLit)
		return (x.Type == nil) == (y.Type == nil) &&
			(x.Type == nil || tr.matchType(x.Type, y.Type)) &&
			tr.matchExprs(x.Elts, y.Elts)

	case *ast.SelectorExpr:
		y := y.(*ast.SelectorExpr)
		return tr.matchSelectorExpr(x, y) &&
			tr.info.Selections[x].Obj() == tr.info.Selections[y].Obj()

	case *ast.IndexExpr:
		y := y.(*ast.IndexExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Index, y.Index)

	case *ast.SliceExpr:
		y := y.(*ast.SliceExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Low, y.Low) &&
			tr.matchExpr(x.High, y.High) &&
			tr.matchExpr(x.Max, y.Max) &&
			x.Slice3 == y.Slice3

	case *ast.TypeAssertExpr:
		y := y.(*ast.TypeAssertExpr)
		return tr.matchExpr(x.X, y.X) &&
			tr.matchType(x.Type, y.Type)

	case *ast.CallExpr:
		y := y.(*ast.CallExpr)
		match := tr.matchExpr // function call
		if tr.info.Types[x.Fun].IsType() {
			match = tr.matchType // type conversion
		}
		return x.Ellipsis.IsValid() == y.Ellipsis.IsValid() &&
			match(x.Fun, y.Fun) &&
			tr.matchExprs(x.Args, y.Args)

	case *ast.StarExpr:
		y := y.(*ast.StarExpr)
		return tr.matchExpr(x.X, y.X)

	case *ast.UnaryExpr:
		y := y.(*ast.UnaryExpr)
		return x.Op == y.Op &&
			tr.matchExpr(x.X, y.X)

	case *ast.BinaryExpr:
		y := y.(*ast.BinaryExpr)
		return x.Op == y.Op &&
			tr.matchExpr(x.X, y.X) &&
			tr.matchExpr(x.Y, y.Y)

	case *ast.KeyValueExpr:
		y := y.(*ast.KeyValueExpr)
		return tr.matchExpr(x.Key, y.Key) &&
			tr.matchExpr(x.Value, y.Value)
	}

	panic(fmt.Sprintf("unhandled AST node type: %T", x))
}

func (tr *Transformer) matchExprs(xx, yy []ast.Expr) bool {
	if len(xx) != len(yy) {
		return false
	}
	for i := range xx {
		if !tr.matchExpr(xx[i], yy[i]) {
			return false
		}
	}
	return true
}

// matchType reports whether the two type ASTs denote identical types.
func (tr *Transformer) matchType(x, y ast.Expr) bool {
	tx := tr.info.Types[x].Type
	ty := tr.info.Types[y].Type
	return types.Identical(tx, ty)
}

func (tr *Transformer) wildcardObj(x ast.Expr) (*types.Var, bool) {
	if x, ok := x.(*ast.Ident); ok && x != nil && tr.allowWildcards {
		if xobj, ok := tr.info.Uses[x].(*types.Var); ok && tr.wildcards[xobj] {
			return xobj, true
		}
	}
	return nil, false
}

func (tr *Transformer) matchSelectorExpr(x, y *ast.SelectorExpr) bool {
	if xobj, ok := tr.wildcardObj(x.X); ok {
		field := x.Sel.Name
		yt := tr.info.TypeOf(y.X)
		o, _, _ := types.LookupFieldOrMethod(yt, true, tr.currentPkg, field)
		if o != nil {
			tr.env[xobj.Name()] = y.X // record binding
			return true
		}
	}
	return tr.matchExpr(x.X, y.X)
}

func (tr *Transformer) matchWildcard(xobj *types.Var, y ast.Expr) bool {
	name := xobj.Name()

	if tr.verbose {
		fmt.Fprintf(os.Stderr, "%s: wildcard %s -> %s?: ",
			tr.fset.Position(y.Pos()), name, astString(tr.fset, y))
	}

	// Check that y is assignable to the declared type of the param.
	yt := tr.info.TypeOf(y)
	if yt == nil {
		// y has no type.
		// Perhaps it is an *ast.Ellipsis in [...]T{}, or
		// an *ast.KeyValueExpr in T{k: v}.
		// Clearly these pseudo-expressions cannot match a
		// wildcard, but it would nice if we had a way to ignore
		// the difference between T{v} and T{k:v} for structs.
		return false
	}
	if !types.AssignableTo(yt, xobj.Type()) {
		if tr.verbose {
			fmt.Fprintf(os.Stderr, "%s not assignable to %s\n", yt, xobj.Type())
		}
		return false
	}

	// A wildcard matches any expression.
	// If it appears multiple times in the pattern, it must match
	// the same expression each time.
	if old, ok := tr.env[name]; ok {
		// found existing binding
		tr.allowWildcards = false
		r := tr.matchExpr(old, y)
		if tr.verbose {
			fmt.Fprintf(os.Stderr, "%t secondary match, primary was %s\n",
				r, astString(tr.fset, old))
		}
		tr.allowWildcards = true
		return r
	}

	if tr.verbose {
		fmt.Fprintf(os.Stderr, "primary match\n")
	}

	tr.env[name] = y // record binding
	return true
}

// -- utilities --------------------------------------------------------

// isRef returns the object referred to by this (possibly qualified)
// identifier, or nil if the node is not a referring identifier.
func isRef(n ast.Node, info *types.Info) types.Object {
	switch n := n.(type) {
	case *ast.Ident:
		return info.Uses[n]

	case *ast.SelectorExpr:
		if _, ok := info.Selections[n]; !ok {
			// qualified ident
			return info.Uses[n.Sel]
		}
	}
	return nil
}


================================================
FILE: refactor/eg/rewrite.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package eg

// This file defines the AST rewriting pass.
// Most of it was plundered directly from
// $GOROOT/src/cmd/gofmt/rewrite.go (after convergent evolution).

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"
	"os"
	"reflect"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/tools/go/ast/astutil"
)

// transformItem takes a reflect.Value representing a variable of type ast.Node
// transforms its child elements recursively with apply, and then transforms the
// actual element if it contains an expression.
func (tr *Transformer) transformItem(rv reflect.Value) (reflect.Value, bool, map[string]ast.Expr) {
	// don't bother if val is invalid to start with
	if !rv.IsValid() {
		return reflect.Value{}, false, nil
	}

	rv, changed, newEnv := tr.apply(tr.transformItem, rv)

	e := rvToExpr(rv)
	if e == nil {
		return rv, changed, newEnv
	}

	savedEnv := tr.env
	tr.env = make(map[string]ast.Expr) // inefficient!  Use a slice of k/v pairs

	if tr.matchExpr(tr.before, e) {
		if tr.verbose {
			fmt.Fprintf(os.Stderr, "%s matches %s",
				astString(tr.fset, tr.before), astString(tr.fset, e))
			if len(tr.env) > 0 {
				fmt.Fprintf(os.Stderr, " with:")
				for name, ast := range tr.env {
					fmt.Fprintf(os.Stderr, " %s->%s",
						name, astString(tr.fset, ast))
				}
			}
			fmt.Fprintf(os.Stderr, "\n")
		}
		tr.nsubsts++

		// Clone the replacement tree, performing parameter substitution.
		// We update all positions to n.Pos() to aid comment placement.
		rv = tr.subst(tr.env, reflect.ValueOf(tr.after),
			reflect.ValueOf(e.Pos()))
		changed = true
		newEnv = tr.env
	}
	tr.env = savedEnv

	return rv, changed, newEnv
}

// Transform applies the transformation to the specified parsed file,
// whose type information is supplied in info, and returns the number
// of replacements that were made.
//
// It mutates the AST in place (the identity of the root node is
// unchanged), and may add nodes for which no type information is
// available in info.
//
// Derived from rewriteFile in $GOROOT/src/cmd/gofmt/rewrite.go.
func (tr *Transformer) Transform(info *types.Info, pkg *types.Package, file *ast.File) int {
	if !tr.seenInfos[info] {
		tr.seenInfos[info] = true
		mergeTypeInfo(tr.info, info)
	}
	tr.currentPkg = pkg
	tr.nsubsts = 0

	if tr.verbose {
		fmt.Fprintf(os.Stderr, "before: %s\n", astString(tr.fset, tr.before))
		fmt.Fprintf(os.Stderr, "after: %s\n", astString(tr.fset, tr.after))
		fmt.Fprintf(os.Stderr, "afterStmts: %s\n", tr.afterStmts)
	}

	o, changed, _ := tr.apply(tr.transformItem, reflect.ValueOf(file))
	if changed {
		panic("BUG")
	}
	file2 := o.Interface().(*ast.File)

	// By construction, the root node is unchanged.
	if file != file2 {
		panic("BUG")
	}

	// Add any necessary imports.
	// TODO(adonovan): remove no-longer needed imports too.
	if tr.nsubsts > 0 {
		pkgs := make(map[string]*types.Package)
		for obj := range tr.importedObjs {
			pkgs[obj.Pkg().Path()] = obj.Pkg()
		}

		for _, imp := range file.Imports {
			path, _ := strconv.Unquote(imp.Path.Value)
			delete(pkgs, path)
		}
		delete(pkgs, pkg.Path()) // don't import self

		// NB: AddImport may completely replace the AST!
		// It thus renders info and tr.info no longer relevant to file.
		var paths []string
		for path := range pkgs {
			paths = append(paths, path)
		}
		sort.Strings(paths)
		for _, path := range paths {
			astutil.AddImport(tr.fset, file, path)
		}
	}

	tr.currentPkg = nil

	return tr.nsubsts
}

// setValue is a wrapper for x.SetValue(y); it protects
// the caller from panics if x cannot be changed to y.
func setValue(x, y reflect.Value) {
	// don't bother if y is invalid to start with
	if !y.IsValid() {
		return
	}
	defer func() {
		if x := recover(); x != nil {
			if s, ok := x.(string); ok &&
				(strings.Contains(s, "type mismatch") || strings.Contains(s, "not assignable")) {
				// x cannot be set to y - ignore this rewrite
				return
			}
			panic(x)
		}
	}()
	x.Set(y)
}

// Values/types for special cases.
var (
	objectPtrNil = reflect.ValueOf((*ast.Object)(nil))
	scopePtrNil  = reflect.ValueOf((*ast.Scope)(nil))

	identType        = reflect.TypeFor[*ast.Ident]()
	selectorExprType = reflect.TypeFor[*ast.SelectorExpr]()
	objectPtrType    = reflect.TypeFor[*ast.Object]()
	statementType    = reflect.TypeFor[ast.Stmt]()
	positionType     = reflect.TypeFor[token.Pos]()
	scopePtrType     = reflect.TypeFor[*ast.Scope]()
)

// apply replaces each AST field x in val with f(x), returning val.
// To avoid extra conversions, f operates on the reflect.Value form.
// f takes a reflect.Value representing the variable to modify of type ast.Node.
// It returns a reflect.Value containing the transformed value of type ast.Node,
// whether any change was made, and a map of identifiers to ast.Expr (so we can
// do contextually correct substitutions in the parent statements).
func (tr *Transformer) apply(f func(reflect.Value) (reflect.Value, bool, map[string]ast.Expr), val reflect.Value) (reflect.Value, bool, map[string]ast.Expr) {
	if !val.IsValid() {
		return reflect.Value{}, false, nil
	}

	// *ast.Objects introduce cycles and are likely incorrect after
	// rewrite; don't follow them but replace with nil instead
	if val.Type() == objectPtrType {
		return objectPtrNil, false, nil
	}

	// similarly for scopes: they are likely incorrect after a rewrite;
	// replace them with nil
	if val.Type() == scopePtrType {
		return scopePtrNil, false, nil
	}

	switch v := reflect.Indirect(val); v.Kind() {
	case reflect.Slice:
		// no possible rewriting of statements.
		if v.Type().Elem() != statementType {
			changed := false
			var envp map[string]ast.Expr
			for i := 0; i < v.Len(); i++ {
				e := v.Index(i)
				o, localchanged, env := f(e)
				if localchanged {
					changed = true
					// we clobber envp here,
					// which means if we have two successive
					// replacements inside the same statement
					// we will only generate the setup for one of them.
					envp = env
				}
				setValue(e, o)
			}
			return val, changed, envp
		}

		// statements are rewritten.
		var out []ast.Stmt
		for i := 0; i < v.Len(); i++ {
			e := v.Index(i)
			o, changed, env := f(e)
			if changed {
				for _, s := range tr.afterStmts {
					t := tr.subst(env, reflect.ValueOf(s), reflect.Value{}).Interface()
					out = append(out, t.(ast.Stmt))
				}
			}
			setValue(e, o)
			out = append(out, e.Interface().(ast.Stmt))
		}
		return reflect.ValueOf(out), false, nil
	case reflect.Struct:
		changed := false
		var envp map[string]ast.Expr
		for i := 0; i < v.NumField(); i++ {
			e := v.Field(i)
			o, localchanged, env := f(e)
			if localchanged {
				changed = true
				envp = env
			}
			setValue(e, o)
		}
		return val, changed, envp
	case reflect.Interface:
		e := v.Elem()
		o, changed, env := f(e)
		setValue(v, o)
		return val, changed, env
	}
	return val, false, nil
}

// subst returns a copy of (replacement) pattern with values from env
// substituted in place of wildcards and pos used as the position of
// tokens from the pattern. If env == nil, subst returns a copy of
// pattern and doesn't change the line number information.
func (tr *Transformer) subst(env map[string]ast.Expr, pattern, pos reflect.Value) reflect.Value {
	if !pattern.IsValid() {
		return reflect.Value{}
	}

	// *ast.Objects introduce cycles and are likely incorrect after
	// rewrite; don't follow them but replace with nil instead
	if pattern.Type() == objectPtrType {
		return objectPtrNil
	}

	// similarly for scopes: they are likely incorrect after a rewrite;
	// replace them with nil
	if pattern.Type() == scopePtrType {
		return scopePtrNil
	}

	// Wildcard gets replaced with map value.
	if env != nil && pattern.Type() == identType {
		id := pattern.Interface().(*ast.Ident)
		if old, ok := env[id.Name]; ok {
			return tr.subst(nil, reflect.ValueOf(old), reflect.Value{})
		}
	}

	// Emit qualified identifiers in the pattern by appropriate
	// (possibly qualified) identifier in the input.
	//
	// The template cannot contain dot imports, so all identifiers
	// for imported objects are explicitly qualified.
	//
	// We assume (unsoundly) that there are no dot or named
	// imports in the input code, nor are any imported package
	// names shadowed, so the usual normal qualified identifier
	// syntax may be used.
	// TODO(adonovan): fix: avoid this assumption.
	//
	// A refactoring may be applied to a package referenced by the
	// template.  Objects belonging to the current package are
	// denoted by unqualified identifiers.
	//
	if tr.importedObjs != nil && pattern.Type() == selectorExprType {
		obj := isRef(pattern.Interface().(*ast.SelectorExpr), tr.info)
		if obj != nil {
			if sel, ok := tr.importedObjs[obj]; ok {
				var id ast.Expr
				if obj.Pkg() == tr.currentPkg {
					id = sel.Sel // unqualified
				} else {
					id = sel // pkg-qualified
				}

				// Return a clone of id.
				saved := tr.importedObjs
				tr.importedObjs = nil // break cycle
				r := tr.subst(nil, reflect.ValueOf(id), pos)
				tr.importedObjs = saved
				return r
			}
		}
	}

	if pos.IsValid() && pattern.Type() == positionType {
		// use new position only if old position was valid in the first place
		if old := pattern.Interface().(token.Pos); !old.IsValid() {
			return pattern
		}
		return pos
	}

	// Otherwise copy.
	switch p := pattern; p.Kind() {
	case reflect.Slice:
		v := reflect.MakeSlice(p.Type(), p.Len(), p.Len())
		for i := 0; i < p.Len(); i++ {
			v.Index(i).Set(tr.subst(env, p.Index(i), pos))
		}
		return v

	case reflect.Struct:
		v := reflect.New(p.Type()).Elem()
		for i := 0; i < p.NumField(); i++ {
			v.Field(i).Set(tr.subst(env, p.Field(i), pos))
		}
		return v

	case reflect.Pointer:
		v := reflect.New(p.Type()).Elem()
		if elem := p.Elem(); elem.IsValid() {
			v.Set(tr.subst(env, elem, pos).Addr())
		}

		// Duplicate type information for duplicated ast.Expr.
		// All ast.Node implementations are *structs,
		// so this case catches them all.
		if e := rvToExpr(v); e != nil {
			updateTypeInfo(tr.info, e, p.Interface().(ast.Expr))
		}
		return v

	case reflect.Interface:
		v := reflect.New(p.Type()).Elem()
		if elem := p.Elem(); elem.IsValid() {
			v.Set(tr.subst(env, elem, pos))
		}
		return v
	}

	return pattern
}

// -- utilities -------------------------------------------------------

func rvToExpr(rv reflect.Value) ast.Expr {
	if rv.CanInterface() {
		if e, ok := rv.Interface().(ast.Expr); ok {
			return e
		}
	}
	return nil
}

// updateTypeInfo duplicates type information for the existing AST old
// so that it also applies to duplicated AST new.
func updateTypeInfo(info *types.Info, new, old ast.Expr) {
	switch new := new.(type) {
	case *ast.Ident:
		orig := old.(*ast.Ident)
		if obj, ok := info.Defs[orig]; ok {
			info.Defs[new] = obj
		}
		if obj, ok := info.Uses[orig]; ok {
			info.Uses[new] = obj
		}

	case *ast.SelectorExpr:
		orig := old.(*ast.SelectorExpr)
		if sel, ok := info.Selections[orig]; ok {
			info.Selections[new] = sel
		}
	}

	if tv, ok := info.Types[old]; ok {
		info.Types[new] = tv
	}
}


================================================
FILE: refactor/eg/testdata/a.txtar
================================================


-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Basic test of type-aware expression refactoring.

import (
	"errors"
	"fmt"
)

func before(s string) error { return fmt.Errorf("%s", s) }
func after(s string) error  { return errors.New(s) }

-- in/a1/a1.go --
package a1

import (
	. "fmt"
	myfmt "fmt"
	"os"
	"strings"
)

func example(n int) {
	x := "foo" + strings.Repeat("\t", n)
	// Match, despite named import.
	myfmt.Errorf("%s", x)

	// Match, despite dot import.
	Errorf("%s", x)

	// Match: multiple matches in same function are possible.
	myfmt.Errorf("%s", x)

	// No match: wildcarded operand has the wrong type.
	myfmt.Errorf("%s", 3)

	// No match: function operand doesn't match.
	myfmt.Printf("%s", x)

	// No match again, dot import.
	Printf("%s", x)

	// Match.
	myfmt.Fprint(os.Stderr, myfmt.Errorf("%s", x+"foo"))

	// No match: though this literally matches the template,
	// fmt doesn't resolve to a package here.
	var fmt struct{ Errorf func(string, string) }
	fmt.Errorf("%s", x)

	// Recursive matching:

	// Match: both matches are well-typed, so both succeed.
	myfmt.Errorf("%s", myfmt.Errorf("%s", x+"foo").Error())

	// Outer match succeeds, inner doesn't: 3 has wrong type.
	myfmt.Errorf("%s", myfmt.Errorf("%s", 3).Error())

	// Inner match succeeds, outer doesn't: the inner replacement
	// has the wrong type (error not string).
	myfmt.Errorf("%s", myfmt.Errorf("%s", x+"foo"))
}

-- out/a1/a1.go --
package a1

import (
	"errors"
	. "fmt"
	myfmt "fmt"
	"os"
	"strings"
)

func example(n int) {
	x := "foo" + strings.Repeat("\t", n)
	// Match, despite named import.
	errors.New(x)

	// Match, despite dot import.
	errors.New(x)

	// Match: multiple matches in same function are possible.
	errors.New(x)

	// No match: wildcarded operand has the wrong type.
	myfmt.Errorf("%s", 3)

	// No match: function operand doesn't match.
	myfmt.Printf("%s", x)

	// No match again, dot import.
	Printf("%s", x)

	// Match.
	myfmt.Fprint(os.Stderr, errors.New(x+"foo"))

	// No match: though this literally matches the template,
	// fmt doesn't resolve to a package here.
	var fmt struct{ Errorf func(string, string) }
	fmt.Errorf("%s", x)

	// Recursive matching:

	// Match: both matches are well-typed, so both succeed.
	errors.New(errors.New(x + "foo").Error())

	// Outer match succeeds, inner doesn't: 3 has wrong type.
	errors.New(myfmt.Errorf("%s", 3).Error())

	// Inner match succeeds, outer doesn't: the inner replacement
	// has the wrong type (error not string).
	myfmt.Errorf("%s", errors.New(x+"foo"))
}
-- a2/a2.go --
package a2

// This refactoring causes addition of "errors" import.
// TODO(adonovan): fix: it should also remove "fmt".

import myfmt "fmt"

func example(n int) {
	myfmt.Errorf("%s", "")
}

-- out/a2/a2.go --
package a2

// This refactoring causes addition of "errors" import.
// TODO(adonovan): fix: it should also remove "fmt".

import (
	"errors"
	myfmt "fmt"
)

func example(n int) {
	errors.New("")
}


================================================
FILE: refactor/eg/testdata/b.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Basic test of expression refactoring.
// (Types are not important in this case; it could be done with gofmt -r.)

import "time"

func before(t time.Time) time.Duration { return time.Now().Sub(t) }
func after(t time.Time) time.Duration  { return time.Since(t) }

-- in/b1/b1.go --
package b1

import "time"

var startup = time.Now()

func example() time.Duration {
	before := time.Now()
	time.Sleep(1)
	return time.Now().Sub(before)
}

func msSinceStartup() int64 {
	return int64(time.Now().Sub(startup) / time.Millisecond)
}

-- out/b1/b1.go --
package b1

import "time"

var startup = time.Now()

func example() time.Duration {
	before := time.Now()
	time.Sleep(1)
	return time.Since(before)
}

func msSinceStartup() int64 {
	return int64(time.Since(startup) / time.Millisecond)
}


================================================
FILE: refactor/eg/testdata/bad_type.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Test in which replacement has a different type.

const shouldFail = "int is not a safe replacement for string"

func before() interface{} { return "three" }
func after() interface{}  { return 3 }


================================================
FILE: refactor/eg/testdata/c.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Test of repeated use of wildcard in pattern.

// NB: multiple patterns would be required to handle variants such as
// s[:len(s)], s[x:len(s)], etc, since a wildcard can't match nothing at all.
// TODO(adonovan): support multiple templates in a single pass.

func before(s string) string { return s[:len(s)] }
func after(s string) string  { return s }

-- in/c1/c1.go --
package C1

import "strings"

func example() {
	x := "foo"
	println(x[:len(x)])

	// Match, but the transformation is not sound w.r.t. possible side effects.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 3))])

	// No match, since second use of wildcard doesn't match first.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])

	// Recursive match demonstrating bottom-up rewrite:
	// only after the inner replacement occurs does the outer syntax match.
	println((x[:len(x)])[:len(x[:len(x)])])
	// -> (x[:len(x)])
	// -> x
}

-- out/c1/c1.go --
package C1

import "strings"

func example() {
	x := "foo"
	println(x)

	// Match, but the transformation is not sound w.r.t. possible side effects.
	println(strings.Repeat("*", 3))

	// No match, since second use of wildcard doesn't match first.
	println(strings.Repeat("*", 3)[:len(strings.Repeat("*", 2))])

	// Recursive match demonstrating bottom-up rewrite:
	// only after the inner replacement occurs does the outer syntax match.
	println(x)
	// -> (x[:len(x)])
	// -> x
}


================================================
FILE: refactor/eg/testdata/d.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import "fmt"

// Test of semantic (not syntactic) matching of basic literals.

func before() (int, error) { return fmt.Println(123, "a") }
func after() (int, error)  { return fmt.Println(456, "!") }

-- in/d1/d1.go --
package d1

import "fmt"

func example() {
	fmt.Println(123, "a")         // match
	fmt.Println(0x7b, `a`)        // match
	fmt.Println(0173, "\x61")     // match
	fmt.Println(100+20+3, "a"+"") // no match: constant expressions, but not basic literals
}

-- out/d1/d1.go --
package d1

import "fmt"

func example() {
	fmt.Println(456, "!")         // match
	fmt.Println(456, "!")         // match
	fmt.Println(456, "!")         // match
	fmt.Println(100+20+3, "a"+"") // no match: constant expressions, but not basic literals
}


================================================
FILE: refactor/eg/testdata/e.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import (
	"fmt"
	"log"
	"os"
)

// Replace call to void function by call to non-void function.

func before(x interface{}) { log.Fatal(x) }
func after(x interface{})  { fmt.Fprintf(os.Stderr, "warning: %v", x) }

-- in/e1/e1.go --
package e1

import "log"

func example() {
	log.Fatal("oops") // match
}

-- out/e1/e1.go --
package e1

import (
	"fmt"
	"log"
	"os"
)

func example() {
	fmt.Fprintf(os.Stderr, "warning: %v", "oops") // match
}


================================================
FILE: refactor/eg/testdata/expr_type_mismatch.txtar
================================================


-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import (
	"crypto/x509"
	"fmt"
)

// This test demonstrates a false negative: according to the language
// rules this replacement should be ok, but types.Assignable doesn't work
// in the expected way (elementwise assignability) for tuples.
// Perhaps that's even a type-checker bug?
const shouldFail = "(n int, err error) is not a safe replacement for (key any, err error)"

func before() (interface{}, error) { return x509.ParsePKCS8PrivateKey(nil) }
func after() (interface{}, error)  { return fmt.Print() }


================================================
FILE: refactor/eg/testdata/f.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

// Test

import "sync"

func before(s sync.RWMutex) { s.Lock() }
func after(s sync.RWMutex)  { s.RLock() }

-- in/f1/f1.go --
package F1

import "sync"

func example(n int) {
	var x struct {
		mutex sync.RWMutex
	}

	var y struct {
		sync.RWMutex
	}

	type l struct {
		sync.RWMutex
	}

	var z struct {
		l
	}

	var a struct {
		*l
	}

	var b struct{ Lock func() }

	// Match
	x.mutex.Lock()

	// Match
	y.Lock()

	// Match indirect
	z.Lock()

	// Should be no match however currently matches due to:
	// https://golang.org/issue/8584
	// Will start failing when this is fixed then just change golden to
	// No match pointer indirect
	// a.Lock()
	a.Lock()

	// No match
	b.Lock()
}

-- out/f1/f1.go --
package F1

import "sync"

func example(n int) {
	var x struct {
		mutex sync.RWMutex
	}

	var y struct {
		sync.RWMutex
	}

	type l struct {
		sync.RWMutex
	}

	var z struct {
		l
	}

	var a struct {
		*l
	}

	var b struct{ Lock func() }

	// Match
	x.mutex.RLock()

	// Match
	y.RLock()

	// Match indirect
	z.RLock()

	// Should be no match however currently matches due to:
	// https://golang.org/issue/8584
	// Will start failing when this is fixed then just change golden to
	// No match pointer indirect
	// a.Lock()
	a.RLock()

	// No match
	b.Lock()
}


================================================
FILE: refactor/eg/testdata/g.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import (
	"go/ast" // defines many unencapsulated structs
	"go/token"
)

func before(from, to token.Pos) ast.BadExpr { return ast.BadExpr{From: from, To: to} }
func after(from, to token.Pos) ast.BadExpr  { return ast.BadExpr{from, to} }

-- in/g1/g1.go --
package g1

import "go/ast"

func example() {
	_ = ast.BadExpr{From: 123, To: 456} // match
	_ = ast.BadExpr{123, 456}           // no match
	_ = ast.BadExpr{From: 123}          // no match
	_ = ast.BadExpr{To: 456}            // no match
}

-- out/g1/g1.go --
package g1

import "go/ast"

func example() {
	_ = ast.BadExpr{123, 456}  // match
	_ = ast.BadExpr{123, 456}  // no match
	_ = ast.BadExpr{From: 123} // no match
	_ = ast.BadExpr{To: 456}   // no match
}


================================================
FILE: refactor/eg/testdata/h.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import (
	"go/ast" // defines many unencapsulated structs
	"go/token"
)

func before(from, to token.Pos) ast.BadExpr { return ast.BadExpr{from, to} }
func after(from, to token.Pos) ast.BadExpr  { return ast.BadExpr{From: from, To: to} }

-- in/h1/h1.go --
package h1

import "go/ast"

func example() {
	_ = ast.BadExpr{From: 123, To: 456} // no match
	_ = ast.BadExpr{123, 456}           // match
	_ = ast.BadExpr{From: 123}          // no match
	_ = ast.BadExpr{To: 456}            // no match
}

-- out/h1/h1.go --
package h1

import "go/ast"

func example() {
	_ = ast.BadExpr{From: 123, To: 456} // no match
	_ = ast.BadExpr{From: 123, To: 456} // match
	_ = ast.BadExpr{From: 123}          // no match
	_ = ast.BadExpr{To: 456}            // no match
}


================================================
FILE: refactor/eg/testdata/i.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import (
	"errors"
	"fmt"
)

func before(s string) error { return fmt.Errorf("%s", s) }
func after(s string) error {
	n := fmt.Sprintf("error - %s", s)
	return errors.New(n)
}

-- in/i1/i1.go --
package i1

import "fmt"

func example() {
	_ = fmt.Errorf("%s", "foo")
}

-- out/i1/i1.go --
package i1

import (
	"errors"
	"fmt"
)

func example() {

	n := fmt.Sprintf("error - %s", "foo")
	_ = errors.New(n)
}


================================================
FILE: refactor/eg/testdata/j.txtar
================================================

-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

import ()

func before(x int) int { return x + x + x }
func after(x int) int {
	temp := x + x
	return temp + x
}

-- in/j1/j1.go --
package j1

import "fmt"

func example() {
	temp := 5
	fmt.Print(temp + temp + temp)
}

-- out/j1/j1.go --
package j1

import "fmt"

func example() {
	temp := 5
	temp := temp + temp
	fmt.Print(temp + temp)
}


================================================
FILE: refactor/eg/testdata/no_after_return.txtar
================================================


-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

func before() int { return 0 }
func after() int  { println(); return 0 }


================================================
FILE: refactor/eg/testdata/no_before.txtar
================================================


-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

const shouldFail = "no 'before' func found in template"

func Before() {}


================================================
FILE: refactor/eg/testdata/type_mismatch.txtar
================================================


-- go.mod --
module example.com
go 1.18

-- template/template.go --
package template

const shouldFail = "different signatures"

func before() int   { return 0 }
func after() string { return "" }


================================================
FILE: refactor/importgraph/graph.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package importgraph computes the forward and reverse import
// dependency graphs for all packages in a Go workspace.
package importgraph // import "golang.org/x/tools/refactor/importgraph"

import (
	"go/build"
	"sync"

	"golang.org/x/tools/go/buildutil"
)

// A Graph is an import dependency graph, either forward or reverse.
//
// The graph maps each node (a package import path) to the set of its
// successors in the graph.  For a forward graph, this is the set of
// imported packages (prerequisites); for a reverse graph, it is the set
// of importing packages (clients).
//
// Graph construction inspects all imports in each package's directory,
// including those in _test.go files, so the resulting graph may be cyclic.
type Graph map[string]map[string]bool

func (g Graph) addEdge(from, to string) {
	edges := g[from]
	if edges == nil {
		edges = make(map[string]bool)
		g[from] = edges
	}
	edges[to] = true
}

// Search returns all the nodes of the graph reachable from
// any of the specified roots, by following edges forwards.
// Relationally, this is the reflexive transitive closure.
func (g Graph) Search(roots ...string) map[string]bool {
	seen := make(map[string]bool)
	var visit func(x string)
	visit = func(x string) {
		if !seen[x] {
			seen[x] = true
			for y := range g[x] {
				visit(y)
			}
		}
	}
	for _, root := range roots {
		visit(root)
	}
	return seen
}

// Build scans the specified Go workspace and builds the forward and
// reverse import dependency graphs for all its packages.
// It also returns a mapping from canonical import paths to errors for packages
// whose loading was not entirely successful.
// A package may appear in the graph and in the errors mapping.
// All package paths are canonical and may contain "/vendor/".
func Build(ctxt *build.Context) (forward, reverse Graph, errors map[string]error) {
	type importEdge struct {
		from, to string
	}
	type pathError struct {
		path string
		err  error
	}

	ch := make(chan any)

	go func() {
		sema := make(chan int, 20) // I/O concurrency limiting semaphore
		var wg sync.WaitGroup
		buildutil.ForEachPackage(ctxt, func(path string, err error) {
			if err != nil {
				ch <- pathError{path, err}
				return
			}

			wg.Add(1)
			go func() {
				defer wg.Done()

				sema <- 1
				bp, err := ctxt.Import(path, "", 0)
				<-sema

				if err != nil {
					if _, ok := err.(*build.NoGoError); ok {
						// empty directory is not an error
					} else {
						ch <- pathError{path, err}
					}
					// Even in error cases, Import usually returns a package.
				}

				// absolutize resolves an import path relative
				// to the current package bp.
				// The absolute form may contain "vendor".
				//
				// The vendoring feature slows down Build by 3×.
				// Here are timings from a 1400 package workspace:
				//    1100ms: current code (with vendor check)
				//     880ms: with a nonblocking cache around ctxt.IsDir
				//     840ms: nonblocking cache with duplicate suppression
				//     340ms: original code (no vendor check)
				// TODO(adonovan): optimize, somehow.
				memo := make(map[string]string)
				absolutize := func(path string) string {
					canon, ok := memo[path]
					if !ok {
						sema <- 1
						bp2, _ := ctxt.Import(path, bp.Dir, build.FindOnly)
						<-sema

						if bp2 != nil {
							canon = bp2.ImportPath
						} else {
							canon = path
						}
						memo[path] = canon
					}
					return canon
				}

				if bp != nil {
					for _, imp := range bp.Imports {
						ch <- importEdge{path, absolutize(imp)}
					}
					for _, imp := range bp.TestImports {
						ch <- importEdge{path, absolutize(imp)}
					}
					for _, imp := range bp.XTestImports {
						ch <- importEdge{path, absolutize(imp)}
					}
				}

			}()
		})
		wg.Wait()
		close(ch)
	}()

	forward = make(Graph)
	reverse = make(Graph)

	for e := range ch {
		switch e := e.(type) {
		case pathError:
			if errors == nil {
				errors = make(map[string]error)
			}
			errors[e.path] = e.err

		case importEdge:
			if e.to == "C" {
				continue // "C" is fake
			}
			forward.addEdge(e.from, e.to)
			reverse.addEdge(e.to, e.from)
		}
	}

	return forward, reverse, errors
}


================================================
FILE: refactor/importgraph/graph_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Incomplete std lib sources on Android.

//go:build !android

package importgraph_test

import (
	"fmt"
	"go/build"
	"os"
	"sort"
	"strings"
	"testing"

	"golang.org/x/tools/internal/packagestest"
	"golang.org/x/tools/refactor/importgraph"

	_ "crypto/hmac" // just for test, below
)

const this = "golang.org/x/tools/refactor/importgraph"

func TestBuild(t *testing.T) {
	exported := packagestest.Export(t, packagestest.GOPATH, []packagestest.Module{
		{Name: "golang.org/x/tools/refactor/importgraph", Files: packagestest.MustCopyFileTree(".")}})
	defer exported.Cleanup()

	var gopath string
	for _, env := range exported.Config.Env {
		eq := strings.Index(env, "=")
		if eq == 0 {
			// We sometimes see keys with a single leading "=" in the environment on Windows.
			// TODO(#49886): What is the correct way to parse them in general?
			eq = strings.Index(env[1:], "=") + 1
		}
		if eq < 0 {
			t.Fatalf("invalid variable in exported.Config.Env: %q", env)
		}
		k := env[:eq]
		v := env[eq+1:]
		if k == "GOPATH" {
			gopath = v
		}

		if os.Getenv(k) == v {
			continue
		}
		defer func(prev string, prevOK bool) {
			if !prevOK {
				if err := os.Unsetenv(k); err != nil {
					t.Fatal(err)
				}
			} else {
				if err := os.Setenv(k, prev); err != nil {
					t.Fatal(err)
				}
			}
		}(os.LookupEnv(k))

		if err := os.Setenv(k, v); err != nil {
			t.Fatal(err)
		}
		t.Logf("%s=%s", k, v)
	}
	if gopath == "" {
		t.Fatal("Failed to fish GOPATH out of env: ", exported.Config.Env)
	}

	var buildContext = build.Default
	buildContext.GOPATH = gopath
	buildContext.Dir = exported.Config.Dir

	forward, reverse, errs := importgraph.Build(&buildContext)
	for path, err := range errs {
		t.Errorf("%s: %s", path, err)
	}
	if t.Failed() {
		return
	}

	// Log the complete graph before the errors, so that the errors are near the
	// end of the log (where we expect them to be).
	nodePrinted := map[string]bool{}
	printNode := func(direction string, from string) {
		key := fmt.Sprintf("%s[%q]", direction, from)
		if nodePrinted[key] {
			return
		}
		nodePrinted[key] = true

		var g importgraph.Graph
		switch direction {
		case "forward":
			g = forward
		case "reverse":
			g = reverse
		default:
			t.Helper()
			t.Fatalf("bad direction: %q", direction)
		}

		t.Log(key)
		var pkgs []string
		for pkg := range g[from] {
			pkgs = append(pkgs, pkg)
		}
		sort.Strings(pkgs)
		for _, pkg := range pkgs {
			t.Logf("\t%s", pkg)
		}
	}

	if testing.Verbose() {
		printNode("forward", this)
		printNode("reverse", this)
	}

	// Test direct edges.
	// We throw in crypto/hmac to prove that external test files
	// (such as this one) are inspected.
	for _, p := range []string{"go/build", "testing", "crypto/hmac"} {
		if !forward[this][p] {
			printNode("forward", this)
			t.Errorf("forward[%q][%q] not found", this, p)
		}
		if !reverse[p][this] {
			printNode("reverse", p)
			t.Errorf("reverse[%q][%q] not found", p, this)
		}
	}

	// Test non-existent direct edges
	for _, p := range []string{"errors", "reflect"} {
		if forward[this][p] {
			printNode("forward", this)
			t.Errorf("unexpected: forward[%q][%q] found", this, p)
		}
		if reverse[p][this] {
			printNode("reverse", p)
			t.Errorf("unexpected: reverse[%q][%q] found", p, this)
		}
	}

	// Test Search is reflexive.
	if !forward.Search(this)[this] {
		printNode("forward", this)
		t.Errorf("irreflexive: forward.Search(importgraph)[importgraph] not found")
	}
	if !reverse.Search(this)[this] {
		printNode("reverse", this)
		t.Errorf("irreflexive: reverse.Search(importgraph)[importgraph] not found")
	}

	// Test Search is transitive.  (There is no direct edge to these packages.)
	for _, p := range []string{"errors", "reflect", "unsafe"} {
		if !forward.Search(this)[p] {
			printNode("forward", this)
			t.Errorf("intransitive: forward.Search(importgraph)[%s] not found", p)
		}
		if !reverse.Search(p)[this] {
			printNode("reverse", p)
			t.Errorf("intransitive: reverse.Search(%s)[importgraph] not found", p)
		}
	}

	// Test strongly-connected components.  Because A's external
	// test package can depend on B, and vice versa, most of the
	// standard libraries are mutually dependent when their external
	// tests are considered.
	//
	// For any nodes x, y in the same SCC, y appears in the results
	// of both forward and reverse searches starting from x
	if !forward.Search("fmt")["io"] ||
		!forward.Search("io")["fmt"] ||
		!reverse.Search("fmt")["io"] ||
		!reverse.Search("io")["fmt"] {
		printNode("forward", "fmt")
		printNode("forward", "io")
		printNode("reverse", "fmt")
		printNode("reverse", "io")
		t.Errorf("fmt and io are not mutually reachable despite being in the same SCC")
	}
}


================================================
FILE: refactor/rename/check.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rename

// This file defines the safety checks for each kind of renaming.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/internal/typeparams"
	"golang.org/x/tools/internal/typesinternal"
	"golang.org/x/tools/refactor/satisfy"
)

// errorf reports an error (e.g. conflict) and prevents file modification.
func (r *renamer) errorf(pos token.Pos, format string, args ...any) {
	r.hadConflicts = true
	reportError(r.iprog.Fset.Position(pos), fmt.Sprintf(format, args...))
}

// check performs safety checks of the renaming of the 'from' object to r.to.
func (r *renamer) check(from types.Object) {
	if r.objsToUpdate[from] {
		return
	}
	r.objsToUpdate[from] = true

	// NB: order of conditions is important.
	if from_, ok := from.(*types.PkgName); ok {
		r.checkInFileBlock(from_)
	} else if from_, ok := from.(*types.Label); ok {
		r.checkLabel(from_)
	} else if typesinternal.IsPackageLevel(from) {
		r.checkInPackageBlock(from)
	} else if v, ok := from.(*types.Var); ok && v.IsField() {
		r.checkStructField(v)
	} else if f, ok := from.(*types.Func); ok && recv(f) != nil {
		r.checkMethod(f)
	} else if isLocal(from) {
		r.checkInLocalScope(from)
	} else {
		r.errorf(from.Pos(), "unexpected %s object %q (please report a bug)\n",
			objectKind(from), from)
	}
}

// checkInFileBlock performs safety checks for renames of objects in the file block,
// i.e. imported package names.
func (r *renamer) checkInFileBlock(from *types.PkgName) {
	// Check import name is not "init".
	if r.to == "init" {
		r.errorf(from.Pos(), "%q is not a valid imported package name", r.to)
	}

	// Check for conflicts between file and package block.
	if prev := from.Pkg().Scope().Lookup(r.to); prev != nil {
		r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
			objectKind(from), from.Name(), r.to)
		r.errorf(prev.Pos(), "\twith this package member %s",
			objectKind(prev))
		return // since checkInPackageBlock would report redundant errors
	}

	// Check for conflicts in lexical scope.
	r.checkInLexicalScope(from, r.packages[from.Pkg()])

	// Finally, modify ImportSpec syntax to add or remove the Name as needed.
	info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
	if from.Imported().Name() == r.to {
		// ImportSpec.Name not needed
		path[1].(*ast.ImportSpec).Name = nil
	} else {
		// ImportSpec.Name needed
		if spec := path[1].(*ast.ImportSpec); spec.Name == nil {
			spec.Name = &ast.Ident{NamePos: spec.Path.Pos(), Name: r.to}
			info.Defs[spec.Name] = from
		}
	}
}

// checkInPackageBlock performs safety checks for renames of
// func/var/const/type objects in the package block.
func (r *renamer) checkInPackageBlock(from types.Object) {
	// Check that there are no references to the name from another
	// package if the renaming would make it unexported.
	if ast.IsExported(from.Name()) && !ast.IsExported(r.to) {
		for pkg, info := range r.packages {
			if pkg == from.Pkg() {
				continue
			}
			if id := someUse(info, from); id != nil &&
				!r.checkExport(id, pkg, from) {
				break
			}
		}
	}

	info := r.packages[from.Pkg()]

	// Check that in the package block, "init" is a function, and never referenced.
	if r.to == "init" {
		kind := objectKind(from)
		if kind == "func" {
			// Reject if intra-package references to it exist.
			for id, obj := range info.Uses {
				if obj == from {
					r.errorf(from.Pos(),
						"renaming this func %q to %q would make it a package initializer",
						from.Name(), r.to)
					r.errorf(id.Pos(), "\tbut references to it exist")
					break
				}
			}
		} else {
			r.errorf(from.Pos(), "you cannot have a %s at package level named %q",
				kind, r.to)
		}
	}

	// Check for conflicts between package block and all file blocks.
	for _, f := range info.Files {
		fileScope := info.Info.Scopes[f]
		b, prev := fileScope.LookupParent(r.to, token.NoPos)
		if b == fileScope {
			r.errorf(from.Pos(), "renaming this %s %q to %q would conflict",
				objectKind(from), from.Name(), r.to)
			r.errorf(prev.Pos(), "\twith this %s",
				objectKind(prev))
			return // since checkInPackageBlock would report redundant errors
		}
	}

	// Check for conflicts in lexical scope.
	if from.Exported() {
		for _, info := range r.packages {
			r.checkInLexicalScope(from, info)
		}
	} else {
		r.checkInLexicalScope(from, info)
	}
}

func (r *renamer) checkInLocalScope(from types.Object) {
	info := r.packages[from.Pkg()]

	// Is this object an implicit local var for a type switch?
	// Each case has its own var, whose position is the decl of y,
	// but Ident in that decl does not appear in the Uses map.
	//
	//   switch y := x.(type) {	 // Defs[Ident(y)] is undefined
	//   case int:    print(y)       // Implicits[CaseClause(int)]    = Var(y_int)
	//   case string: print(y)       // Implicits[CaseClause(string)] = Var(y_string)
	//   }
	//
	var isCaseVar bool
	for syntax, obj := range info.Implicits {
		if _, ok := syntax.(*ast.CaseClause); ok && obj.Pos() == from.Pos() {
			isCaseVar = true
			r.check(obj)
		}
	}

	r.checkInLexicalScope(from, info)

	// Finally, if this was a type switch, change the variable y.
	if isCaseVar {
		_, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
		path[0].(*ast.Ident).Name = r.to // path is [Ident AssignStmt TypeSwitchStmt...]
	}
}

// checkInLexicalScope performs safety checks that a renaming does not
// change the lexical reference structure of the specified package.
//
// For objects in lexical scope, there are three kinds of conflicts:
// same-, sub-, and super-block conflicts.  We will illustrate all three
// using this example:
//
//	var x int
//	var z int
//
//	func f(y int) {
//		print(x)
//		print(y)
//	}
//
// Renaming x to z encounters a SAME-BLOCK CONFLICT, because an object
// with the new name already exists, defined in the same lexical block
// as the old object.
//
// Renaming x to y encounters a SUB-BLOCK CONFLICT, because there exists
// a reference to x from within (what would become) a hole in its scope.
// The definition of y in an (inner) sub-block would cast a shadow in
// the scope of the renamed variable.
//
// Renaming y to x encounters a SUPER-BLOCK CONFLICT.  This is the
// converse situation: there is an existing definition of the new name
// (x) in an (enclosing) super-block, and the renaming would create a
// hole in its scope, within which there exist references to it.  The
// new name casts a shadow in scope of the existing definition of x in
// the super-block.
//
// Removing the old name (and all references to it) is always safe, and
// requires no checks.
func (r *renamer) checkInLexicalScope(from types.Object, info *loader.PackageInfo) {
	b := from.Parent() // the block defining the 'from' object
	if b != nil {
		toBlock, to := b.LookupParent(r.to, from.Parent().End())
		if toBlock == b {
			// same-block conflict
			r.errorf(from.Pos(), "renaming this %s %q to %q",
				objectKind(from), from.Name(), r.to)
			r.errorf(to.Pos(), "\tconflicts with %s in same block",
				objectKind(to))
			return
		} else if toBlock != nil {
			// Check for super-block conflict.
			// The name r.to is defined in a superblock.
			// Is that name referenced from within this block?
			forEachLexicalRef(info, to, func(id *ast.Ident, block *types.Scope) bool {
				_, obj := lexicalLookup(block, from.Name(), id.Pos())
				if obj == from {
					// super-block conflict
					r.errorf(from.Pos(), "renaming this %s %q to %q",
						objectKind(from), from.Name(), r.to)
					r.errorf(id.Pos(), "\twould shadow this reference")
					r.errorf(to.Pos(), "\tto the %s declared here",
						objectKind(to))
					return false // stop
				}
				return true
			})
		}
	}

	// Check for sub-block conflict.
	// Is there an intervening definition of r.to between
	// the block defining 'from' and some reference to it?
	forEachLexicalRef(info, from, func(id *ast.Ident, block *types.Scope) bool {
		// Find the block that defines the found reference.
		// It may be an ancestor.
		fromBlock, _ := lexicalLookup(block, from.Name(), id.Pos())

		// See what r.to would resolve to in the same scope.
		toBlock, to := lexicalLookup(block, r.to, id.Pos())
		if to != nil {
			// sub-block conflict
			if deeper(toBlock, fromBlock) {
				r.errorf(from.Pos(), "renaming this %s %q to %q",
					objectKind(from), from.Name(), r.to)
				r.errorf(id.Pos(), "\twould cause this reference to become shadowed")
				r.errorf(to.Pos(), "\tby this intervening %s definition",
					objectKind(to))
				return false // stop
			}
		}
		return true
	})

	// Renaming a type that is used as an embedded field
	// requires renaming the field too. e.g.
	// 	type T int // if we rename this to U..
	// 	var s struct {T}
	// 	print(s.T) // ...this must change too
	if _, ok := from.(*types.TypeName); ok {
		for id, obj := range info.Uses {
			if obj == from {
				if field := info.Defs[id]; field != nil {
					r.check(field)
				}
			}
		}
	}
}

// lexicalLookup is like (*types.Scope).LookupParent but respects the
// environment visible at pos.  It assumes the relative position
// information is correct with each file.
func lexicalLookup(block *types.Scope, name string, pos token.Pos) (*types.Scope, types.Object) {
	for b := block; b != nil; b = b.Parent() {
		obj := b.Lookup(name)
		// The scope of a package-level object is the entire package,
		// so ignore pos in that case.
		// No analogous clause is needed for file-level objects
		// since no reference can appear before an import decl.
		if obj != nil && (b == obj.Pkg().Scope() || obj.Pos() < pos) {
			return b, obj
		}
	}
	return nil, nil
}

// deeper reports whether block x is lexically deeper than y.
func deeper(x, y *types.Scope) bool {
	if x == y || x == nil {
		return false
	} else if y == nil {
		return true
	} else {
		return deeper(x.Parent(), y.Parent())
	}
}

// forEachLexicalRef calls fn(id, block) for each identifier id in package
// info that is a reference to obj in lexical scope.  block is the
// lexical block enclosing the reference.  If fn returns false the
// iteration is terminated and findLexicalRefs returns false.
func forEachLexicalRef(info *loader.PackageInfo, obj types.Object, fn func(id *ast.Ident, block *types.Scope) bool) bool {
	ok := true

	var visit func(n ast.Node, stack []ast.Node) bool
	visit = func(n ast.Node, stack []ast.Node) bool {
		if !ok {
			return false // bail out
		}
		switch n := n.(type) {
		case *ast.Ident:
			if info.Uses[n] == obj {
				block := enclosingBlock(&info.Info, stack)
				if !fn(n, block) {
					ok = false
				}
			}
			return false

		case *ast.SelectorExpr:
			// don't visit n.Sel
			ast.PreorderStack(n.X, stack, visit)
			return false // don't descend

		case *ast.CompositeLit:
			// Handle recursion ourselves for struct literals
			// so we don't visit field identifiers.
			tv := info.Types[n]
			if is[*types.Struct](typeparams.CoreType(typeparams.Deref(tv.Type))) {
				if n.Type != nil {
					ast.PreorderStack(n.Type, stack, visit)
				}
				for _, elt := range n.Elts {
					if kv, ok := elt.(*ast.KeyValueExpr); ok {
						ast.PreorderStack(kv.Value, stack, visit)
					} else {
						ast.PreorderStack(elt, stack, visit)
					}
				}
				return false // don't descend
			}
		}
		return true
	}

	for _, f := range info.Files {
		ast.PreorderStack(f, nil, visit)
		if !ok {
			break
		}
	}
	return ok
}

// enclosingBlock returns the innermost block enclosing the specified
// AST node, specified in the form of a path from the root of the file,
// [file...n].
func enclosingBlock(info *types.Info, stack []ast.Node) *types.Scope {
	for i := range stack {
		n := stack[len(stack)-1-i]
		// For some reason, go/types always associates a
		// function's scope with its FuncType.
		// TODO(adonovan): feature or a bug?
		switch f := n.(type) {
		case *ast.FuncDecl:
			n = f.Type
		case *ast.FuncLit:
			n = f.Type
		}
		if b := info.Scopes[n]; b != nil {
			return b
		}
	}
	panic("no Scope for *ast.File")
}

func (r *renamer) checkLabel(label *types.Label) {
	// Check there are no identical labels in the function's label block.
	// (Label blocks don't nest, so this is easy.)
	if prev := label.Parent().Lookup(r.to); prev != nil {
		r.errorf(label.Pos(), "renaming this label %q to %q", label.Name(), prev.Name())
		r.errorf(prev.Pos(), "\twould conflict with this one")
	}
}

// checkStructField checks that the field renaming will not cause
// conflicts at its declaration, or ambiguity or changes to any selection.
func (r *renamer) checkStructField(from *types.Var) {
	// Check that the struct declaration is free of field conflicts,
	// and field/method conflicts.

	// go/types offers no easy way to get from a field (or interface
	// method) to its declaring struct (or interface), so we must
	// ascend the AST.
	info, path, _ := r.iprog.PathEnclosingInterval(from.Pos(), from.Pos())
	// path matches this pattern:
	// [Ident SelectorExpr? StarExpr? Field FieldList StructType ParenExpr* ... File]

	// Ascend to FieldList.
	var i int
	for {
		if _, ok := path[i].(*ast.FieldList); ok {
			break
		}
		i++
	}
	i++
	tStruct := path[i].(*ast.StructType)
	i++
	// Ascend past parens (unlikely).
	for {
		_, ok := path[i].(*ast.ParenExpr)
		if !ok {
			break
		}
		i++
	}
	if spec, ok := path[i].(*ast.TypeSpec); ok && !spec.Assign.IsValid() {
		// This struct is also a defined type.
		// We must check for direct (non-promoted) field/field
		// and method/field conflicts.
		named := info.Defs[spec.Name].Type()
		prev, indices, _ := types.LookupFieldOrMethod(named, true, info.Pkg, r.to)
		if len(indices) == 1 {
			r.errorf(from.Pos(), "renaming this field %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this %s",
				objectKind(prev))
			return // skip checkSelections to avoid redundant errors
		}
	} else {
		// This struct is not a defined type. (It may be an alias.)
		// We need only check for direct (non-promoted) field/field conflicts.
		T := info.Types[tStruct].Type.Underlying().(*types.Struct)
		for field := range T.Fields() {
			if prev := field; prev.Name() == r.to {
				r.errorf(from.Pos(), "renaming this field %q to %q",
					from.Name(), r.to)
				r.errorf(prev.Pos(), "\twould conflict with this field")
				return // skip checkSelections to avoid redundant errors
			}
		}
	}

	// Renaming an anonymous field requires renaming the TypeName too. e.g.
	// 	print(s.T)       // if we rename T to U,
	// 	type T int       // this and
	// 	var s struct {T} // this must change too.
	if from.Anonymous() {
		// A TypeParam cannot appear as an anonymous field.
		if t, ok := typesinternal.Unpointer(from.Type()).(hasTypeName); ok {
			r.check(t.Obj())
		}
	}

	// Check integrity of existing (field and method) selections.
	r.checkSelections(from)
}

// hasTypeName abstracts the named types, *types.{Named,Alias,TypeParam}.
type hasTypeName interface{ Obj() *types.TypeName }

// checkSelections checks that all uses and selections that resolve to
// the specified object would continue to do so after the renaming.
func (r *renamer) checkSelections(from types.Object) {
	for pkg, info := range r.packages {
		if id := someUse(info, from); id != nil {
			if !r.checkExport(id, pkg, from) {
				return
			}
		}

		for syntax, sel := range info.Selections {
			// There may be extant selections of only the old
			// name or only the new name, so we must check both.
			// (If neither, the renaming is sound.)
			//
			// In both cases, we wish to compare the lengths
			// of the implicit field path (Selection.Index)
			// to see if the renaming would change it.
			//
			// If a selection that resolves to 'from', when renamed,
			// would yield a path of the same or shorter length,
			// this indicates ambiguity or a changed referent,
			// analogous to same- or sub-block lexical conflict.
			//
			// If a selection using the name 'to' would
			// yield a path of the same or shorter length,
			// this indicates ambiguity or shadowing,
			// analogous to same- or super-block lexical conflict.

			// TODO(adonovan): fix: derive from Types[syntax.X].Mode
			// TODO(adonovan): test with pointer, value, addressable value.
			isAddressable := true

			if sel.Obj() == from {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), r.to); obj != nil {
					// Renaming this existing selection of
					// 'from' may block access to an existing
					// type member named 'to'.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue // no ambiguity
					}
					r.selectionConflict(from, delta, syntax, obj)
					return
				}

			} else if sel.Obj().Name() == r.to {
				if obj, indices, _ := types.LookupFieldOrMethod(sel.Recv(), isAddressable, from.Pkg(), from.Name()); obj == from {
					// Renaming 'from' may cause this existing
					// selection of the name 'to' to change
					// its meaning.
					delta := len(indices) - len(sel.Index())
					if delta > 0 {
						continue //  no ambiguity
					}
					r.selectionConflict(from, -delta, syntax, sel.Obj())
					return
				}
			}
		}
	}
}

func (r *renamer) selectionConflict(from types.Object, delta int, syntax *ast.SelectorExpr, obj types.Object) {
	r.errorf(from.Pos(), "renaming this %s %q to %q",
		objectKind(from), from.Name(), r.to)

	switch {
	case delta < 0:
		// analogous to sub-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould change the referent of this selection")
		r.errorf(obj.Pos(), "\tof this %s", objectKind(obj))
	case delta == 0:
		// analogous to same-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould make this reference ambiguous")
		r.errorf(obj.Pos(), "\twith this %s", objectKind(obj))
	case delta > 0:
		// analogous to super-block conflict
		r.errorf(syntax.Sel.Pos(),
			"\twould shadow this selection")
		r.errorf(obj.Pos(), "\tof the %s declared here",
			objectKind(obj))
	}
}

// checkMethod performs safety checks for renaming a method.
// There are three hazards:
//   - declaration conflicts
//   - selection ambiguity/changes
//   - entailed renamings of assignable concrete/interface types.
//
// We reject renamings initiated at concrete methods if it would
// change the assignability relation.  For renamings of abstract
// methods, we rename all methods transitively coupled to it via
// assignability.
func (r *renamer) checkMethod(from *types.Func) {
	// e.g. error.Error
	if from.Pkg() == nil {
		r.errorf(from.Pos(), "you cannot rename built-in method %s", from)
		return
	}

	// ASSIGNABILITY: We reject renamings of concrete methods that
	// would break a 'satisfy' constraint; but renamings of abstract
	// methods are allowed to proceed, and we rename affected
	// concrete and abstract methods as necessary.  It is the
	// initial method that determines the policy.

	// Check for conflict at point of declaration.
	// Check to ensure preservation of assignability requirements.
	R := recv(from).Type()
	if types.IsInterface(R) {
		// Abstract method

		// declaration
		prev, _, _ := types.LookupFieldOrMethod(R, false, from.Pkg(), r.to)
		if prev != nil {
			r.errorf(from.Pos(), "renaming this interface method %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this method")
			return
		}

		// Check all interfaces that embed this one for
		// declaration conflicts too.
		for _, info := range r.packages {
			// Start with named interface types (better errors)
			for _, obj := range info.Defs {
				if obj, ok := obj.(*types.TypeName); ok && types.IsInterface(obj.Type()) {
					f, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), from.Name())
					if f == nil {
						continue
					}
					t, _, _ := types.LookupFieldOrMethod(
						obj.Type(), false, from.Pkg(), r.to)
					if t == nil {
						continue
					}
					r.errorf(from.Pos(), "renaming this interface method %q to %q",
						from.Name(), r.to)
					r.errorf(t.Pos(), "\twould conflict with this method")
					r.errorf(obj.Pos(), "\tin named interface type %q", obj.Name())
				}
			}

			// Now look at all literal interface types (includes named ones again).
			for e, tv := range info.Types {
				if e, ok := e.(*ast.InterfaceType); ok {
					_ = e
					_ = tv.Type.(*types.Interface)
					// TODO(adonovan): implement same check as above.
				}
			}
		}

		// assignability
		//
		// Find the set of concrete or abstract methods directly
		// coupled to abstract method 'from' by some
		// satisfy.Constraint, and rename them too.
		for key := range r.satisfy() {
			// key = (lhs, rhs) where lhs is always an interface.

			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
			if lsel == nil {
				continue
			}
			rmethods := r.msets.MethodSet(key.RHS)
			rsel := rmethods.Lookup(from.Pkg(), from.Name())
			if rsel == nil {
				continue
			}

			// If both sides have a method of this name,
			// and one of them is m, the other must be coupled.
			var coupled *types.Func
			switch from {
			case lsel.Obj():
				coupled = rsel.Obj().(*types.Func)
			case rsel.Obj():
				coupled = lsel.Obj().(*types.Func)
			default:
				continue
			}

			// We must treat concrete-to-interface
			// constraints like an implicit selection C.f of
			// each interface method I.f, and check that the
			// renaming leaves the selection unchanged and
			// unambiguous.
			//
			// Fun fact: the implicit selection of C.f
			// 	type I interface{f()}
			// 	type C struct{I}
			// 	func (C) g()
			//      var _ I = C{} // here
			// yields abstract method I.f.  This can make error
			// messages less than obvious.
			//
			if !types.IsInterface(key.RHS) {
				// The logic below was derived from checkSelections.

				rtosel := rmethods.Lookup(from.Pkg(), r.to)
				if rtosel != nil {
					rto := rtosel.Obj().(*types.Func)
					delta := len(rsel.Index()) - len(rtosel.Index())
					if delta < 0 {
						continue // no ambiguity
					}

					// TODO(adonovan): record the constraint's position.
					keyPos := token.NoPos

					r.errorf(from.Pos(), "renaming this method %q to %q",
						from.Name(), r.to)
					if delta == 0 {
						// analogous to same-block conflict
						r.errorf(keyPos, "\twould make the %s method of %s invoked via interface %s ambiguous",
							r.to, key.RHS, key.LHS)
						r.errorf(rto.Pos(), "\twith (%s).%s",
							recv(rto).Type(), r.to)
					} else {
						// analogous to super-block conflict
						r.errorf(keyPos, "\twould change the %s method of %s invoked via interface %s",
							r.to, key.RHS, key.LHS)
						r.errorf(coupled.Pos(), "\tfrom (%s).%s",
							recv(coupled).Type(), r.to)
						r.errorf(rto.Pos(), "\tto (%s).%s",
							recv(rto).Type(), r.to)
					}
					return // one error is enough
				}
			}

			if !r.changeMethods {
				// This should be unreachable.
				r.errorf(from.Pos(), "internal error: during renaming of abstract method %s", from)
				r.errorf(coupled.Pos(), "\tchangedMethods=false, coupled method=%s", coupled)
				r.errorf(from.Pos(), "\tPlease file a bug report")
				return
			}

			// Rename the coupled method to preserve assignability.
			r.check(coupled)
		}
	} else {
		// Concrete method

		// declaration
		prev, indices, _ := types.LookupFieldOrMethod(R, true, from.Pkg(), r.to)
		if prev != nil && len(indices) == 1 {
			r.errorf(from.Pos(), "renaming this method %q to %q",
				from.Name(), r.to)
			r.errorf(prev.Pos(), "\twould conflict with this %s",
				objectKind(prev))
			return
		}

		// assignability
		//
		// Find the set of abstract methods coupled to concrete
		// method 'from' by some satisfy.Constraint, and rename
		// them too.
		//
		// Coupling may be indirect, e.g. I.f <-> C.f via type D.
		//
		// 	type I interface {f()}
		//	type C int
		//	type (C) f()
		//	type D struct{C}
		//	var _ I = D{}
		//
		for key := range r.satisfy() {
			// key = (lhs, rhs) where lhs is always an interface.
			if types.IsInterface(key.RHS) {
				continue
			}
			rsel := r.msets.MethodSet(key.RHS).Lookup(from.Pkg(), from.Name())
			if rsel == nil || rsel.Obj() != from {
				continue // rhs does not have the method
			}
			lsel := r.msets.MethodSet(key.LHS).Lookup(from.Pkg(), from.Name())
			if lsel == nil {
				continue
			}
			imeth := lsel.Obj().(*types.Func)

			// imeth is the abstract method (e.g. I.f)
			// and key.RHS is the concrete coupling type (e.g. D).
			if !r.changeMethods {
				r.errorf(from.Pos(), "renaming this method %q to %q",
					from.Name(), r.to)
				var pos token.Pos
				var iface string

				I := recv(imeth).Type()
				if named, ok := I.(hasTypeName); ok { // *Named or *Alias
					pos = named.Obj().Pos()
					iface = "interface " + named.Obj().Name()
				} else {
					pos = from.Pos()
					iface = I.String()
				}
				r.errorf(pos, "\twould make %s no longer assignable to %s",
					key.RHS, iface)
				r.errorf(imeth.Pos(), "\t(rename %s.%s if you intend to change both types)",
					I, from.Name())
				return // one error is enough
			}

			// Rename the coupled interface method to preserve assignability.
			r.check(imeth)
		}
	}

	// Check integrity of existing (field and method) selections.
	// We skip this if there were errors above, to avoid redundant errors.
	r.checkSelections(from)
}

func (r *renamer) checkExport(id *ast.Ident, pkg *types.Package, from types.Object) bool {
	// Reject cross-package references if r.to is unexported.
	// (Such references may be qualified identifiers or field/method
	// selections.)
	if !ast.IsExported(r.to) && pkg != from.Pkg() {
		r.errorf(from.Pos(),
			"renaming this %s %q to %q would make it unexported",
			objectKind(from), from.Name(), r.to)
		r.errorf(id.Pos(), "\tbreaking references from packages such as %q",
			pkg.Path())
		return false
	}
	return true
}

// satisfy returns the set of interface satisfaction constraints.
func (r *renamer) satisfy() map[satisfy.Constraint]bool {
	if r.satisfyConstraints == nil {
		// Compute on demand: it's expensive.
		var f satisfy.Finder
		for _, info := range r.packages {
			f.Find(&info.Info, info.Files)
		}
		r.satisfyConstraints = f.Result
	}
	return r.satisfyConstraints
}

// -- helpers ----------------------------------------------------------

// recv returns the method's receiver.
func recv(meth *types.Func) *types.Var {
	return meth.Signature().Recv()
}

// someUse returns an arbitrary use of obj within info.
func someUse(info *loader.PackageInfo, obj types.Object) *ast.Ident {
	for id, o := range info.Uses {
		if o == obj {
			return id
		}
	}
	return nil
}


================================================
FILE: refactor/rename/mvpkg.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file contains the implementation of the 'gomvpkg' command
// whose main function is in golang.org/x/tools/cmd/gomvpkg.

package rename

// TODO(matloob):
// - think about what happens if the package is moving across version control systems.
// - dot imports are not supported. Make sure it's clearly documented.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/format"
	"go/token"
	"log"
	"os"
	"os/exec"
	"path"
	"path/filepath"
	"regexp"
	"runtime"
	"strconv"
	"strings"
	"text/template"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/refactor/importgraph"
)

// Move, given a package path and a destination package path, will try
// to move the given package to the new path. The Move function will
// first check for any conflicts preventing the move, such as a
// package already existing at the destination package path. If the
// move can proceed, it builds an import graph to find all imports of
// the packages whose paths need to be renamed. This includes uses of
// the subpackages of the package to be moved as those packages will
// also need to be moved. It then renames all imports to point to the
// new paths, and then moves the packages to their new paths.
func Move(ctxt *build.Context, from, to, moveTmpl string) error {
	srcDir, err := srcDir(ctxt, from)
	if err != nil {
		return err
	}

	// This should be the only place in the program that constructs
	// file paths.
	fromDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(from))
	toDir := buildutil.JoinPath(ctxt, srcDir, filepath.FromSlash(to))
	toParent := filepath.Dir(toDir)
	if !buildutil.IsDir(ctxt, toParent) {
		return fmt.Errorf("parent directory does not exist for path %s", toDir)
	}

	// Build the import graph and figure out which packages to update.
	_, rev, errors := importgraph.Build(ctxt)
	if len(errors) > 0 {
		// With a large GOPATH tree, errors are inevitable.
		// Report them but proceed.
		fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
		for path, err := range errors {
			fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
		}
	}

	// Determine the affected packages---the set of packages whose import
	// statements need updating.
	affectedPackages := map[string]bool{from: true}
	destinations := make(map[string]string) // maps old import path to new import path
	for pkg := range subpackages(ctxt, srcDir, from) {
		for r := range rev[pkg] {
			affectedPackages[r] = true
		}
		destinations[pkg] = strings.Replace(pkg, from, to, 1)
	}

	// Load all the affected packages.
	iprog, err := loadProgram(ctxt, affectedPackages)
	if err != nil {
		return err
	}

	// Prepare the move command, if one was supplied.
	var cmd string
	if moveTmpl != "" {
		if cmd, err = moveCmd(moveTmpl, fromDir, toDir); err != nil {
			return err
		}
	}

	m := mover{
		ctxt:             ctxt,
		rev:              rev,
		iprog:            iprog,
		from:             from,
		to:               to,
		fromDir:          fromDir,
		toDir:            toDir,
		affectedPackages: affectedPackages,
		destinations:     destinations,
		cmd:              cmd,
	}

	if err := m.checkValid(); err != nil {
		return err
	}

	m.move()

	return nil
}

// srcDir returns the absolute path of the srcdir containing pkg.
func srcDir(ctxt *build.Context, pkg string) (string, error) {
	for _, srcDir := range ctxt.SrcDirs() {
		path := buildutil.JoinPath(ctxt, srcDir, pkg)
		if buildutil.IsDir(ctxt, path) {
			return srcDir, nil
		}
	}
	return "", fmt.Errorf("src dir not found for package: %s", pkg)
}

// subpackages returns the set of packages in the given srcDir whose
// import path equals to root, or has "root/" as the prefix.
func subpackages(ctxt *build.Context, srcDir string, root string) map[string]bool {
	var subs = make(map[string]bool)
	buildutil.ForEachPackage(ctxt, func(pkg string, err error) {
		if err != nil {
			log.Fatalf("unexpected error in ForEachPackage: %v", err)
		}

		// Only process the package root, or a sub-package of it.
		if !(strings.HasPrefix(pkg, root) &&
			(len(pkg) == len(root) || pkg[len(root)] == '/')) {
			return
		}

		p, err := ctxt.Import(pkg, "", build.FindOnly)
		if err != nil {
			log.Fatalf("unexpected: package %s can not be located by build context: %s", pkg, err)
		}
		if p.SrcRoot == "" {
			log.Fatalf("unexpected: could not determine srcDir for package %s: %s", pkg, err)
		}
		if p.SrcRoot != srcDir {
			return
		}

		subs[pkg] = true
	})
	return subs
}

type mover struct {
	// iprog contains all packages whose contents need to be updated
	// with new package names or import paths.
	iprog *loader.Program
	ctxt  *build.Context
	// rev is the reverse import graph.
	rev importgraph.Graph
	// from and to are the source and destination import
	// paths. fromDir and toDir are the source and destination
	// absolute paths that package source files will be moved between.
	from, to, fromDir, toDir string
	// affectedPackages is the set of all packages whose contents need
	// to be updated to reflect new package names or import paths.
	affectedPackages map[string]bool
	// destinations maps each subpackage to be moved to its
	// destination path.
	destinations map[string]string
	// cmd, if not empty, will be executed to move fromDir to toDir.
	cmd string
}

func (m *mover) checkValid() error {
	const prefix = "invalid move destination"

	match, err := regexp.MatchString("^[_\\pL][_\\pL\\p{Nd}]*$", path.Base(m.to))
	if err != nil {
		panic("regexp.MatchString failed")
	}
	if !match {
		return fmt.Errorf("%s: %s; gomvpkg does not support move destinations "+
			"whose base names are not valid go identifiers", prefix, m.to)
	}

	if buildutil.FileExists(m.ctxt, m.toDir) {
		return fmt.Errorf("%s: %s conflicts with file %s", prefix, m.to, m.toDir)
	}
	if buildutil.IsDir(m.ctxt, m.toDir) {
		return fmt.Errorf("%s: %s conflicts with directory %s", prefix, m.to, m.toDir)
	}

	for _, toSubPkg := range m.destinations {
		if _, err := m.ctxt.Import(toSubPkg, "", build.FindOnly); err == nil {
			return fmt.Errorf("%s: %s; package or subpackage %s already exists",
				prefix, m.to, toSubPkg)
		}
	}

	return nil
}

// moveCmd produces the version control move command used to move fromDir to toDir by
// executing the given template.
func moveCmd(moveTmpl, fromDir, toDir string) (string, error) {
	tmpl, err := template.New("movecmd").Parse(moveTmpl)
	if err != nil {
		return "", err
	}

	var buf bytes.Buffer
	err = tmpl.Execute(&buf, struct {
		Src string
		Dst string
	}{fromDir, toDir})
	return buf.String(), err
}

func (m *mover) move() error {
	filesToUpdate := make(map[*ast.File]bool)

	// Change the moved package's "package" declaration to its new base name.
	pkg, ok := m.iprog.Imported[m.from]
	if !ok {
		log.Fatalf("unexpected: package %s is not in import map", m.from)
	}
	newName := filepath.Base(m.to)
	for _, f := range pkg.Files {
		// Update all import comments.
		for _, cg := range f.Comments {
			c := cg.List[0]
			if c.Slash >= f.Name.End() &&
				sameLine(m.iprog.Fset, c.Slash, f.Name.End()) &&
				(f.Decls == nil || c.Slash < f.Decls[0].Pos()) {
				if strings.HasPrefix(c.Text, `// import "`) {
					c.Text = `// import "` + m.to + `"`
					break
				}
				if strings.HasPrefix(c.Text, `/* import "`) {
					c.Text = `/* import "` + m.to + `" */`
					break
				}
			}
		}
		f.Name.Name = newName // change package decl
		filesToUpdate[f] = true
	}

	// Look through the external test packages (m.iprog.Created contains the external test packages).
	for _, info := range m.iprog.Created {
		// Change the "package" declaration of the external test package.
		if info.Pkg.Path() == m.from+"_test" {
			for _, f := range info.Files {
				f.Name.Name = newName + "_test" // change package decl
				filesToUpdate[f] = true
			}
		}

		// Mark all the loaded external test packages, which import the "from" package,
		// as affected packages and update the imports.
		for _, imp := range info.Pkg.Imports() {
			if imp.Path() == m.from {
				m.affectedPackages[info.Pkg.Path()] = true
				m.iprog.Imported[info.Pkg.Path()] = info
				if err := importName(m.iprog, info, m.from, path.Base(m.from), newName); err != nil {
					return err
				}
			}
		}
	}

	// Update imports of that package to use the new import name.
	// None of the subpackages will change their name---only the from package
	// itself will.
	for p := range m.rev[m.from] {
		if err := importName(m.iprog, m.iprog.Imported[p], m.from, path.Base(m.from), newName); err != nil {
			return err
		}
	}

	// Update import paths for all imports by affected packages.
	for ap := range m.affectedPackages {
		info, ok := m.iprog.Imported[ap]
		if !ok {
			log.Fatalf("unexpected: package %s is not in import map", ap)
		}
		for _, f := range info.Files {
			for _, imp := range f.Imports {
				importPath, _ := strconv.Unquote(imp.Path.Value)
				if newPath, ok := m.destinations[importPath]; ok {
					imp.Path.Value = strconv.Quote(newPath)

					oldName := path.Base(importPath)
					if imp.Name != nil {
						oldName = imp.Name.Name
					}

					newName := path.Base(newPath)
					if imp.Name == nil && oldName != newName {
						imp.Name = ast.NewIdent(oldName)
					} else if imp.Name == nil || imp.Name.Name == newName {
						imp.Name = nil
					}
					filesToUpdate[f] = true
				}
			}
		}
	}

	for f := range filesToUpdate {
		var buf bytes.Buffer
		if err := format.Node(&buf, m.iprog.Fset, f); err != nil {
			log.Printf("failed to pretty-print syntax tree: %v", err)
			continue
		}
		tokenFile := m.iprog.Fset.File(f.FileStart)
		writeFile(tokenFile.Name(), buf.Bytes())
	}

	// Move the directories.
	// If either the fromDir or toDir are contained under version control it is
	// the user's responsibility to provide a custom move command that updates
	// version control to reflect the move.
	// TODO(matloob): If the parent directory of toDir does not exist, create it.
	//      For now, it's required that it does exist.

	if m.cmd != "" {
		// TODO(matloob): Verify that the windows and plan9 cases are correct.
		var cmd *exec.Cmd
		switch runtime.GOOS {
		case "windows":
			cmd = exec.Command("cmd", "/c", m.cmd)
		case "plan9":
			cmd = exec.Command("rc", "-c", m.cmd)
		default:
			cmd = exec.Command("sh", "-c", m.cmd)
		}
		cmd.Stderr = os.Stderr
		cmd.Stdout = os.Stdout
		if err := cmd.Run(); err != nil {
			return fmt.Errorf("version control system's move command failed: %v", err)
		}

		return nil
	}

	return moveDirectory(m.fromDir, m.toDir)
}

// sameLine reports whether two positions in the same file are on the same line.
func sameLine(fset *token.FileSet, x, y token.Pos) bool {
	return fset.Position(x).Line == fset.Position(y).Line
}

var moveDirectory = func(from, to string) error {
	return os.Rename(from, to)
}


================================================
FILE: refactor/rename/mvpkg_test.go
================================================
// Copyright 2015 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rename

import (
	"fmt"
	"go/build"
	"go/token"
	"io"
	"path/filepath"
	"reflect"
	"regexp"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
)

func TestErrors(t *testing.T) {
	tests := []struct {
		ctxt     *build.Context
		from, to string
		want     string // regexp to match error, or "OK"
	}{
		// Simple example.
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"bar": {`package bar`},
				"main": {`package main

import "foo"

var _ foo.T
`},
			}),
			from: "foo", to: "bar",
			want: `invalid move destination: bar conflicts with directory .go.src.bar`,
		},
		// Subpackage already exists.
		{
			ctxt: fakeContext(map[string][]string{
				"foo":     {`package foo; type T int`},
				"foo/sub": {`package sub`},
				"bar/sub": {`package sub`},
				"main": {`package main

import "foo"

var _ foo.T
`},
			}),
			from: "foo", to: "bar",
			want: "invalid move destination: bar; package or subpackage bar/sub already exists",
		},
		// Invalid base name.
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

var _ foo.T
`},
			}),
			from: "foo", to: "bar-v2.0",
			want: "invalid move destination: bar-v2.0; gomvpkg does not " +
				"support move destinations whose base names are not valid " +
				"go identifiers",
		},
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {``},
				"bar": {`package bar`},
			}),
			from: "foo", to: "bar",
			want: `no initial packages were loaded`,
		},
	}

	for _, test := range tests {
		ctxt := test.ctxt

		got := make(map[string]string)
		writeFile = func(filename string, content []byte) error {
			got[filename] = string(content)
			return nil
		}
		moveDirectory = func(from, to string) error {
			for path, contents := range got {
				if strings.HasPrefix(path, from) {
					newPath := strings.Replace(path, from, to, 1)
					delete(got, path)
					got[newPath] = contents
				}
			}
			return nil
		}

		err := Move(ctxt, test.from, test.to, "")
		prefix := fmt.Sprintf("-from %q -to %q", test.from, test.to)
		if err == nil {
			t.Errorf("%s: nil error. Expected error: %s", prefix, test.want)
			continue
		}
		matched, err2 := regexp.MatchString(test.want, err.Error())
		if err2 != nil {
			t.Errorf("regexp.MatchString failed %s", err2)
			continue
		}
		if !matched {
			t.Errorf("%s: conflict does not match expectation:\n"+
				"Error: %q\n"+
				"Pattern: %q",
				prefix, err.Error(), test.want)
		}
	}
}

func TestMoves(t *testing.T) {
	tests := []struct {
		ctxt         *build.Context
		from, to     string
		want         map[string]string
		wantWarnings []string
	}{
		// Simple example.
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

var _ foo.T
`},
			}),
			from: "foo", to: "bar",
			want: map[string]string{
				"/go/src/main/0.go": `package main

import "bar"

var _ bar.T
`,
				"/go/src/bar/0.go": `package bar

type T int
`,
			},
		},

		// Example with subpackage.
		{
			ctxt: fakeContext(map[string][]string{
				"foo":     {`package foo; type T int`},
				"foo/sub": {`package sub; type T int`},
				"main": {`package main

import "foo"
import "foo/sub"

var _ foo.T
var _ sub.T
`},
			}),
			from: "foo", to: "bar",
			want: map[string]string{
				"/go/src/main/0.go": `package main

import "bar"
import "bar/sub"

var _ bar.T
var _ sub.T
`,
				"/go/src/bar/0.go": `package bar

type T int
`,
				"/go/src/bar/sub/0.go": `package sub; type T int`,
			},
		},

		// References into subpackages
		{
			ctxt: fakeContext(map[string][]string{
				"foo":   {`package foo; import "foo/a"; var _ a.T`},
				"foo/a": {`package a; type T int`},
				"foo/b": {`package b; import "foo/a"; var _ a.T`},
			}),
			from: "foo", to: "bar",
			want: map[string]string{
				"/go/src/bar/0.go": `package bar

import "bar/a"

var _ a.T
`,
				"/go/src/bar/a/0.go": `package a; type T int`,
				"/go/src/bar/b/0.go": `package b

import "bar/a"

var _ a.T
`,
			},
		},

		// References into subpackages where directories have overlapped names
		{
			ctxt: fakeContext(map[string][]string{
				"foo":    {},
				"foo/a":  {`package a`},
				"foo/aa": {`package bar`},
				"foo/c":  {`package c; import _ "foo/bar";`},
			}),
			from: "foo/a", to: "foo/spam",
			want: map[string]string{
				"/go/src/foo/spam/0.go": `package spam
`,
				"/go/src/foo/aa/0.go": `package bar`,
				"/go/src/foo/c/0.go":  `package c; import _ "foo/bar";`,
			},
		},

		// External test packages
		{
			ctxt: buildutil.FakeContext(map[string]map[string]string{
				"foo": {
					"0.go":      `package foo; type T int`,
					"0_test.go": `package foo_test; import "foo"; var _ foo.T`,
				},
				"baz": {
					"0_test.go": `package baz_test; import "foo"; var _ foo.T`,
				},
			}),
			from: "foo", to: "bar",
			want: map[string]string{
				"/go/src/bar/0.go": `package bar

type T int
`,
				"/go/src/bar/0_test.go": `package bar_test

import "bar"

var _ bar.T
`,
				"/go/src/baz/0_test.go": `package baz_test

import "bar"

var _ bar.T
`,
			},
		},
		// package import comments
		{
			ctxt: fakeContext(map[string][]string{"foo": {`package foo // import "baz"`}}),
			from: "foo", to: "bar",
			want: map[string]string{"/go/src/bar/0.go": `package bar // import "bar"
`},
		},
		{
			ctxt: fakeContext(map[string][]string{"foo": {`package foo /* import "baz" */`}}),
			from: "foo", to: "bar",
			want: map[string]string{"/go/src/bar/0.go": `package bar /* import "bar" */
`},
		},
		{
			ctxt: fakeContext(map[string][]string{"foo": {`package foo       // import "baz"`}}),
			from: "foo", to: "bar",
			want: map[string]string{"/go/src/bar/0.go": `package bar // import "bar"
`},
		},
		{
			ctxt: fakeContext(map[string][]string{"foo": {`package foo
// import " this is not an import comment`}}),
			from: "foo", to: "bar",
			want: map[string]string{"/go/src/bar/0.go": `package bar

// import " this is not an import comment
`},
		},
		{
			ctxt: fakeContext(map[string][]string{"foo": {`package foo
/* import " this is not an import comment */`}}),
			from: "foo", to: "bar",
			want: map[string]string{"/go/src/bar/0.go": `package bar

/* import " this is not an import comment */
`},
		},
		// Import name conflict generates a warning, not an error.
		{
			ctxt: fakeContext(map[string][]string{
				"x": {},
				"a": {`package a; type A int`},
				"b": {`package b; type B int`},
				"conflict": {`package conflict

import "a"
import "b"
var _ a.A
var _ b.B
`},
				"ok": {`package ok
import "b"
var _ b.B
`},
			}),
			from: "b", to: "x/a",
			want: map[string]string{
				"/go/src/a/0.go": `package a; type A int`,
				"/go/src/ok/0.go": `package ok

import "x/a"

var _ a.B
`,
				"/go/src/conflict/0.go": `package conflict

import "a"
import "x/a"

var _ a.A
var _ b.B
`,
				"/go/src/x/a/0.go": `package a

type B int
`,
			},
			wantWarnings: []string{
				`/go/src/conflict/0.go:4:8: renaming this imported package name "b" to "a"`,
				`/go/src/conflict/0.go:3:8: 	conflicts with imported package name in same block`,
				`/go/src/conflict/0.go:3:8: skipping update of this file`,
			},
		},
		// Rename with same base name.
		{
			ctxt: fakeContext(map[string][]string{
				"x": {},
				"y": {},
				"x/foo": {`package foo

type T int
`},
				"main": {`package main; import "x/foo"; var _ foo.T`},
			}),
			from: "x/foo", to: "y/foo",
			want: map[string]string{
				"/go/src/y/foo/0.go": `package foo

type T int
`,
				"/go/src/main/0.go": `package main

import "y/foo"

var _ foo.T
`,
			},
		},
	}

	for _, test := range tests {
		ctxt := test.ctxt

		got := make(map[string]string)
		// Populate got with starting file set. rewriteFile and moveDirectory
		// will mutate got to produce resulting file set.
		buildutil.ForEachPackage(ctxt, func(importPath string, err error) {
			if err != nil {
				return
			}
			path := filepath.Join("/go/src", importPath, "0.go")
			if !buildutil.FileExists(ctxt, path) {
				return
			}
			f, err := ctxt.OpenFile(path)
			if err != nil {
				t.Errorf("unexpected error opening file: %s", err)
				return
			}
			bytes, err := io.ReadAll(f)
			f.Close()
			if err != nil {
				t.Errorf("unexpected error reading file: %s", err)
				return
			}
			got[path] = string(bytes)
		})
		var warnings []string
		reportError = func(posn token.Position, message string) {
			warning := fmt.Sprintf("%s:%d:%d: %s",
				filepath.ToSlash(posn.Filename), // for MS Windows
				posn.Line,
				posn.Column,
				message)
			warnings = append(warnings, warning)

		}
		writeFile = func(filename string, content []byte) error {
			got[filename] = string(content)
			return nil
		}
		moveDirectory = func(from, to string) error {
			for path, contents := range got {
				if !(strings.HasPrefix(path, from) &&
					(len(path) == len(from) || path[len(from)] == filepath.Separator)) {
					continue
				}
				newPath := strings.Replace(path, from, to, 1)
				delete(got, path)
				got[newPath] = contents
			}
			return nil
		}

		err := Move(ctxt, test.from, test.to, "")
		prefix := fmt.Sprintf("-from %q -to %q", test.from, test.to)
		if err != nil {
			t.Errorf("%s: unexpected error: %s", prefix, err)
			continue
		}

		if !reflect.DeepEqual(warnings, test.wantWarnings) {
			t.Errorf("%s: unexpected warnings:\n%s\nwant:\n%s",
				prefix,
				strings.Join(warnings, "\n"),
				strings.Join(test.wantWarnings, "\n"))
		}

		for file, wantContent := range test.want {
			k := filepath.FromSlash(file)
			gotContent, ok := got[k]
			delete(got, k)
			if !ok {
				// TODO(matloob): some testcases might have files that won't be
				// rewritten
				t.Errorf("%s: file %s not rewritten", prefix, file)
				continue
			}
			if gotContent != wantContent {
				t.Errorf("%s: rewritten file %s does not match expectation; got <<<%s>>>\n"+
					"want <<<%s>>>", prefix, file, gotContent, wantContent)
			}
		}
		// got should now be empty
		for file := range got {
			t.Errorf("%s: unexpected rewrite of file %s", prefix, file)
		}
	}
}


================================================
FILE: refactor/rename/rename.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package rename contains the obsolete implementation of the deleted
// golang.org/x/tools/cmd/gorename. This logic has not worked properly
// since the advent of Go modules, and should be deleted too.
//
// Use gopls instead, either via the Rename LSP method or the "gopls
// rename" subcommand.
package rename

import (
	"bytes"
	"errors"
	"fmt"
	"go/ast"
	"go/build"
	"go/format"
	"go/parser"
	"go/token"
	"go/types"
	"io"
	"log"
	"os"
	"os/exec"
	"path"
	"regexp"
	"sort"
	"strconv"
	"strings"

	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/refactor/importgraph"
	"golang.org/x/tools/refactor/satisfy"
)

const Usage = `gorename: precise type-safe renaming of identifiers in Go source code.

Usage:

 gorename (-from <spec> | -offset <file>:#<byte-offset>) -to <name> [-force]

You must specify the object (named entity) to rename using the -offset
or -from flag.  Exactly one must be specified.

Flags:

-offset    specifies the filename and byte offset of an identifier to rename.
           This form is intended for use by text editors.

-from      specifies the object to rename using a query notation;
           This form is intended for interactive use at the command line.
           A legal -from query has one of the following forms:

  "encoding/json".Decoder.Decode        method of package-level named type
  (*"encoding/json".Decoder).Decode     ditto, alternative syntax
  "encoding/json".Decoder.buf           field of package-level named struct type
  "encoding/json".HTMLEscape            package member (const, func, var, type)
  "encoding/json".Decoder.Decode::x     local object x within a method
  "encoding/json".HTMLEscape::x         local object x within a function
  "encoding/json"::x                    object x anywhere within a package
  json.go::x                            object x within file json.go

           Double-quotes must be escaped when writing a shell command.
           Quotes may be omitted for single-segment import paths such as "fmt".

           For methods, the parens and '*' on the receiver type are both
           optional.

           It is an error if one of the ::x queries matches multiple
           objects.

-to        the new name.

-force     causes the renaming to proceed even if conflicts were reported.
           The resulting program may be ill-formed, or experience a change
           in behaviour.

           WARNING: this flag may even cause the renaming tool to crash.
           (In due course this bug will be fixed by moving certain
           analyses into the type-checker.)

-d         display diffs instead of rewriting files

-v         enables verbose logging.

gorename automatically computes the set of packages that might be
affected.  For a local renaming, this is just the package specified by
-from or -offset, but for a potentially exported name, gorename scans
the workspace ($GOROOT and $GOPATH).

gorename rejects renamings of concrete methods that would change the
assignability relation between types and interfaces. If the interface
change was intentional, initiate the renaming at the interface method.

gorename rejects any renaming that would create a conflict at the point
of declaration, or a reference conflict (ambiguity or shadowing), or
anything else that could cause the resulting program not to compile.


Examples:

$ gorename -offset file.go:#123 -to foo

  Rename the object whose identifier is at byte offset 123 within file file.go.

$ gorename -from '"bytes".Buffer.Len' -to Size

  Rename the "Len" method of the *bytes.Buffer type to "Size".
`

// ---- TODO ----

// Correctness:
// - handle dot imports correctly
// - document limitations (reflection, 'implements' algorithm).
// - sketch a proof of exhaustiveness.

// Features:
// - support running on packages specified as *.go files on the command line
// - support running on programs containing errors (loader.Config.AllowErrors)
// - allow users to specify a scope other than "global" (to avoid being
//   stuck by neglected packages in $GOPATH that don't build).
// - support renaming the package clause (no object)
// - support renaming an import path (no ident or object)
//   (requires filesystem + SCM updates).
// - detect and reject edits to autogenerated files (cgo, protobufs)
//   and optionally $GOROOT packages.
// - report all conflicts, or at least all qualitatively distinct ones.
//   Sometimes we stop to avoid redundancy, but
//   it may give a disproportionate sense of safety in -force mode.
// - support renaming all instances of a pattern, e.g.
//   all receiver vars of a given type,
//   all local variables of a given type,
//   all PkgNames for a given package.
// - emit JSON output for other editors and tools.

var (
	// Force enables patching of the source files even if conflicts were reported.
	// The resulting program may be ill-formed.
	// It may even cause gorename to crash.  TODO(adonovan): fix that.
	Force bool

	// Diff causes the tool to display diffs instead of rewriting files.
	Diff bool

	// DiffCmd specifies the diff command used by the -d feature.
	// (The command must accept a -u flag and two filename arguments.)
	DiffCmd = "diff"

	// ConflictError is returned by Main when it aborts the renaming due to conflicts.
	// (It is distinguished because the interesting errors are the conflicts themselves.)
	ConflictError = errors.New("renaming aborted due to conflicts")

	// Verbose enables extra logging.
	Verbose bool
)

var stdout io.Writer = os.Stdout

type renamer struct {
	iprog              *loader.Program
	objsToUpdate       map[types.Object]bool
	hadConflicts       bool
	from, to           string
	satisfyConstraints map[satisfy.Constraint]bool
	packages           map[*types.Package]*loader.PackageInfo // subset of iprog.AllPackages to inspect
	msets              typeutil.MethodSetCache
	changeMethods      bool
}

var reportError = func(posn token.Position, message string) {
	fmt.Fprintf(os.Stderr, "%s: %s\n", posn, message)
}

// importName renames imports of fromPath within the package specified by info.
// If fromName is not empty, importName renames only imports as fromName.
// If the renaming would lead to a conflict, the file is left unchanged.
func importName(iprog *loader.Program, info *loader.PackageInfo, fromPath, fromName, to string) error {
	if fromName == to {
		return nil // no-op (e.g. rename x/foo to y/foo)
	}
	for _, f := range info.Files {
		var from types.Object
		for _, imp := range f.Imports {
			importPath, _ := strconv.Unquote(imp.Path.Value)
			importName := path.Base(importPath)
			if imp.Name != nil {
				importName = imp.Name.Name
			}
			if importPath == fromPath && (fromName == "" || importName == fromName) {
				from = info.Implicits[imp]
				break
			}
		}
		if from == nil {
			continue
		}
		r := renamer{
			iprog:        iprog,
			objsToUpdate: make(map[types.Object]bool),
			to:           to,
			packages:     map[*types.Package]*loader.PackageInfo{info.Pkg: info},
		}
		r.check(from)
		if r.hadConflicts {
			reportError(iprog.Fset.Position(f.Imports[0].Pos()),
				"skipping update of this file")
			continue // ignore errors; leave the existing name
		}
		if err := r.update(); err != nil {
			return err
		}
	}
	return nil
}

func Main(ctxt *build.Context, offsetFlag, fromFlag, to string) error {
	// -- Parse the -from or -offset specifier ----------------------------

	if (offsetFlag == "") == (fromFlag == "") {
		return fmt.Errorf("exactly one of the -from and -offset flags must be specified")
	}

	if !isValidIdentifier(to) {
		return fmt.Errorf("-to %q: not a valid identifier", to)
	}

	if Diff {
		defer func(saved func(string, []byte) error) { writeFile = saved }(writeFile)
		writeFile = diff
	}

	var spec *spec
	var err error
	if fromFlag != "" {
		spec, err = parseFromFlag(ctxt, fromFlag)
	} else {
		spec, err = parseOffsetFlag(ctxt, offsetFlag)
	}
	if err != nil {
		return err
	}

	if spec.fromName == to {
		return fmt.Errorf("the old and new names are the same: %s", to)
	}

	// -- Load the program consisting of the initial package  -------------

	iprog, err := loadProgram(ctxt, map[string]bool{spec.pkg: true})
	if err != nil {
		return err
	}

	fromObjects, err := findFromObjects(iprog, spec)
	if err != nil {
		return err
	}

	// -- Load a larger program, for global renamings ---------------------

	if requiresGlobalRename(fromObjects, to) {
		// For a local refactoring, we needn't load more
		// packages, but if the renaming affects the package's
		// API, we must load all packages that depend on the
		// package defining the object, plus their tests.

		if Verbose {
			log.Print("Potentially global renaming; scanning workspace...")
		}

		// Scan the workspace and build the import graph.
		_, rev, errors := importgraph.Build(ctxt)
		if len(errors) > 0 {
			// With a large GOPATH tree, errors are inevitable.
			// Report them but proceed.
			fmt.Fprintf(os.Stderr, "While scanning Go workspace:\n")
			for path, err := range errors {
				fmt.Fprintf(os.Stderr, "Package %q: %s.\n", path, err)
			}
		}

		// Enumerate the set of potentially affected packages.
		affectedPackages := make(map[string]bool)
		for _, obj := range fromObjects {
			// External test packages are never imported,
			// so they will never appear in the graph.
			for path := range rev.Search(obj.Pkg().Path()) {
				affectedPackages[path] = true
			}
		}

		// TODO(adonovan): allow the user to specify the scope,
		// or -ignore patterns?  Computing the scope when we
		// don't (yet) support inputs containing errors can make
		// the tool rather brittle.

		// Re-load the larger program.
		iprog, err = loadProgram(ctxt, affectedPackages)
		if err != nil {
			return err
		}

		fromObjects, err = findFromObjects(iprog, spec)
		if err != nil {
			return err
		}
	}

	// -- Do the renaming -------------------------------------------------

	r := renamer{
		iprog:        iprog,
		objsToUpdate: make(map[types.Object]bool),
		from:         spec.fromName,
		to:           to,
		packages:     make(map[*types.Package]*loader.PackageInfo),
	}

	// A renaming initiated at an interface method indicates the
	// intention to rename abstract and concrete methods as needed
	// to preserve assignability.
	for _, obj := range fromObjects {
		if obj, ok := obj.(*types.Func); ok {
			recv := obj.Signature().Recv()
			if recv != nil && types.IsInterface(recv.Type()) {
				r.changeMethods = true
				break
			}
		}
	}

	// Only the initially imported packages (iprog.Imported) and
	// their external tests (iprog.Created) should be inspected or
	// modified, as only they have type-checked function bodies.
	// The rest are just dependencies, needed only for package-level
	// type information.
	for _, info := range iprog.Imported {
		r.packages[info.Pkg] = info
	}
	for _, info := range iprog.Created { // (tests)
		r.packages[info.Pkg] = info
	}

	for _, from := range fromObjects {
		r.check(from)
	}
	if r.hadConflicts && !Force {
		return ConflictError
	}
	return r.update()
}

// loadProgram loads the specified set of packages (plus their tests)
// and all their dependencies, from source, through the specified build
// context.  Only packages in pkgs will have their functions bodies typechecked.
func loadProgram(ctxt *build.Context, pkgs map[string]bool) (*loader.Program, error) {
	conf := loader.Config{
		Build:      ctxt,
		ParserMode: parser.ParseComments,

		// TODO(adonovan): enable this.  Requires making a lot of code more robust!
		AllowErrors: false,
	}
	// Optimization: don't type-check the bodies of functions in our
	// dependencies, since we only need exported package members.
	conf.TypeCheckFuncBodies = func(p string) bool {
		return pkgs[p] || pkgs[strings.TrimSuffix(p, "_test")]
	}

	if Verbose {
		var list []string
		for pkg := range pkgs {
			list = append(list, pkg)
		}
		sort.Strings(list)
		for _, pkg := range list {
			log.Printf("Loading package: %s", pkg)
		}
	}

	for pkg := range pkgs {
		conf.ImportWithTests(pkg)
	}

	// Ideally we would just return conf.Load() here, but go/types
	// reports certain "soft" errors that gc does not (Go issue 14596).
	// As a workaround, we set AllowErrors=true and then duplicate
	// the loader's error checking but allow soft errors.
	// It would be nice if the loader API permitted "AllowErrors: soft".
	conf.AllowErrors = true
	prog, err := conf.Load()
	if err != nil {
		return nil, err
	}

	var errpkgs []string
	// Report hard errors in indirectly imported packages.
	for _, info := range prog.AllPackages {
		if containsHardErrors(info.Errors) {
			errpkgs = append(errpkgs, info.Pkg.Path())
		}
	}
	if errpkgs != nil {
		var more string
		if len(errpkgs) > 3 {
			more = fmt.Sprintf(" and %d more", len(errpkgs)-3)
			errpkgs = errpkgs[:3]
		}
		return nil, fmt.Errorf("couldn't load packages due to errors: %s%s",
			strings.Join(errpkgs, ", "), more)
	}
	return prog, nil
}

func containsHardErrors(errors []error) bool {
	for _, err := range errors {
		if err, ok := err.(types.Error); ok && err.Soft {
			continue
		}
		return true
	}
	return false
}

// requiresGlobalRename reports whether this renaming could potentially
// affect other packages in the Go workspace.
func requiresGlobalRename(fromObjects []types.Object, to string) bool {
	var tfm bool
	for _, from := range fromObjects {
		if from.Exported() {
			return true
		}
		switch objectKind(from) {
		case "type", "field", "method":
			tfm = true
		}
	}
	if ast.IsExported(to) && tfm {
		// A global renaming may be necessary even if we're
		// exporting a previous unexported name, since if it's
		// the name of a type, field or method, this could
		// change selections in other packages.
		// (We include "type" in this list because a type
		// used as an embedded struct field entails a field
		// renaming.)
		return true
	}
	return false
}

// update updates the input files.
func (r *renamer) update() error {
	// We use token.File, not filename, since a file may appear to
	// belong to multiple packages and be parsed more than once.
	// token.File captures this distinction; filename does not.

	var nidents int
	var filesToUpdate = make(map[*token.File]bool)
	docRegexp := regexp.MustCompile(`\b` + r.from + `\b`)
	for _, info := range r.packages {
		// Mutate the ASTs and note the filenames.
		for id, obj := range info.Defs {
			if r.objsToUpdate[obj] {
				nidents++
				id.Name = r.to
				filesToUpdate[r.iprog.Fset.File(id.Pos())] = true
				// Perform the rename in doc comments too.
				if doc := r.docComment(id); doc != nil {
					for _, comment := range doc.List {
						comment.Text = docRegexp.ReplaceAllString(comment.Text, r.to)
					}
				}
			}
		}

		for id, obj := range info.Uses {
			if r.objsToUpdate[obj] {
				nidents++
				id.Name = r.to
				filesToUpdate[r.iprog.Fset.File(id.Pos())] = true
			}
		}
	}

	// Renaming not supported if cgo files are affected.
	var generatedFileNames []string
	for _, info := range r.packages {
		for _, f := range info.Files {
			tokenFile := r.iprog.Fset.File(f.FileStart)
			if filesToUpdate[tokenFile] && ast.IsGenerated(f) {
				generatedFileNames = append(generatedFileNames, tokenFile.Name())
			}
		}
	}
	if !Force && len(generatedFileNames) > 0 {
		return fmt.Errorf("refusing to modify generated file%s containing DO NOT EDIT marker: %v", plural(len(generatedFileNames)), generatedFileNames)
	}

	// Write affected files.
	var nerrs, npkgs int
	for _, info := range r.packages {
		first := true
		for _, f := range info.Files {
			tokenFile := r.iprog.Fset.File(f.FileStart)
			if filesToUpdate[tokenFile] {
				if first {
					npkgs++
					first = false
					if Verbose {
						log.Printf("Updating package %s", info.Pkg.Path())
					}
				}

				filename := tokenFile.Name()
				var buf bytes.Buffer
				if err := format.Node(&buf, r.iprog.Fset, f); err != nil {
					log.Printf("failed to pretty-print syntax tree: %v", err)
					nerrs++
					continue
				}
				if err := writeFile(filename, buf.Bytes()); err != nil {
					log.Print(err)
					nerrs++
				}
			}
		}
	}
	if !Diff {
		fmt.Printf("Renamed %d occurrence%s in %d file%s in %d package%s.\n",
			nidents, plural(nidents),
			len(filesToUpdate), plural(len(filesToUpdate)),
			npkgs, plural(npkgs))
	}
	if nerrs > 0 {
		return fmt.Errorf("failed to rewrite %d file%s", nerrs, plural(nerrs))
	}
	return nil
}

// docComment returns the doc for an identifier.
func (r *renamer) docComment(id *ast.Ident) *ast.CommentGroup {
	_, nodes, _ := r.iprog.PathEnclosingInterval(id.Pos(), id.End())
	for _, node := range nodes {
		switch decl := node.(type) {
		case *ast.FuncDecl:
			return decl.Doc
		case *ast.Field:
			return decl.Doc
		case *ast.GenDecl:
			return decl.Doc
		// For {Type,Value}Spec, if the doc on the spec is absent,
		// search for the enclosing GenDecl
		case *ast.TypeSpec:
			if decl.Doc != nil {
				return decl.Doc
			}
		case *ast.ValueSpec:
			if decl.Doc != nil {
				return decl.Doc
			}
		case *ast.Ident:
		default:
			return nil
		}
	}
	return nil
}

func plural(n int) string {
	if n != 1 {
		return "s"
	}
	return ""
}

// writeFile is a seam for testing and for the -d flag.
var writeFile = reallyWriteFile

func reallyWriteFile(filename string, content []byte) error {
	return os.WriteFile(filename, content, 0644)
}

func diff(filename string, content []byte) error {
	renamed := fmt.Sprintf("%s.%d.renamed", filename, os.Getpid())
	if err := os.WriteFile(renamed, content, 0644); err != nil {
		return err
	}
	defer os.Remove(renamed)

	diff, err := exec.Command(DiffCmd, "-u", filename, renamed).Output()
	if len(diff) > 0 {
		// diff exits with a non-zero status when the files don't match.
		// Ignore that failure as long as we get output.
		stdout.Write(diff)
		return nil
	}
	if err != nil {
		if exit, ok := err.(*exec.ExitError); ok && len(exit.Stderr) > 0 {
			err = fmt.Errorf("%w\nstderr:\n%s", err, exit.Stderr)
		}
		return fmt.Errorf("computing diff: %v", err)
	}
	return nil
}


================================================
FILE: refactor/rename/rename_test.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rename

import (
	"bytes"
	"fmt"
	"go/build"
	"go/token"
	"os"
	"os/exec"
	"path/filepath"
	"regexp"
	"runtime"
	"strings"
	"testing"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/internal/testenv"
)

// TODO(adonovan): test reported source positions, somehow.

func TestConflicts(t *testing.T) {
	defer func(savedWriteFile func(string, []byte) error, savedReportError func(token.Position, string)) {
		writeFile = savedWriteFile
		reportError = savedReportError
	}(writeFile, reportError)
	writeFile = func(string, []byte) error { return nil }

	var ctxt *build.Context
	for _, test := range []struct {
		ctxt             *build.Context // nil => use previous
		offset, from, to string         // values of the -offset/-from and -to flags
		want             string         // regexp to match conflict errors, or "OK"
	}{
		// init() checks
		{
			ctxt: fakeContext(map[string][]string{
				"fmt": {`package fmt; type Stringer interface { String() }`},
				"main": {`
package main

import foo "fmt"

var v foo.Stringer

func f() { v.String(); f() }
`,
					`package main; var w int`},
			}),
			from: "main.v", to: "init",
			want: `you cannot have a var at package level named "init"`,
		},
		{
			from: "main.f", to: "init",
			want: `renaming this func "f" to "init" would make it a package initializer.*` +
				`but references to it exist`,
		},
		{
			from: "/go/src/main/0.go::foo", to: "init",
			want: `"init" is not a valid imported package name`,
		},

		// Export checks
		{
			from: "fmt.Stringer", to: "stringer",
			want: `renaming this type "Stringer" to "stringer" would make it unexported.*` +
				`breaking references from packages such as "main"`,
		},
		{
			from: "(fmt.Stringer).String", to: "string",
			want: `renaming this method "String" to "string" would make it unexported.*` +
				`breaking references from packages such as "main"`,
		},

		// Lexical scope checks
		{
			// file/package conflict, same file
			from: "main.v", to: "foo",
			want: `renaming this var "v" to "foo" would conflict.*` +
				`with this imported package name`,
		},
		{
			// file/package conflict, same file
			from: "main::foo", to: "v",
			want: `renaming this imported package name "foo" to "v" would conflict.*` +
				`with this package member var`,
		},
		{
			// file/package conflict, different files
			from: "main.w", to: "foo",
			want: `renaming this var "w" to "foo" would conflict.*` +
				`with this imported package name`,
		},
		{
			// file/package conflict, different files
			from: "main::foo", to: "w",
			want: `renaming this imported package name "foo" to "w" would conflict.*` +
				`with this package member var`,
		},
		{
			ctxt: main(`
package main

var x, z int

func f(y int) {
	print(x)
	print(y)
}

func g(w int) {
	print(x)
	x := 1
	print(x)
}`),
			from: "main.x", to: "y",
			want: `renaming this var "x" to "y".*` +
				`would cause this reference to become shadowed.*` +
				`by this intervening var definition`,
		},
		{
			from: "main.g::x", to: "w",
			want: `renaming this var "x" to "w".*` +
				`conflicts with var in same block`,
		},
		{
			from: "main.f::y", to: "x",
			want: `renaming this var "y" to "x".*` +
				`would shadow this reference.*` +
				`to the var declared here`,
		},
		{
			from: "main.g::w", to: "x",
			want: `renaming this var "w" to "x".*` +
				`conflicts with var in same block`,
		},
		{
			from: "main.z", to: "y", want: "OK",
		},

		// Label checks
		{
			ctxt: main(`
package main

func f() {
foo:
	goto foo
bar:
	goto bar
	func(x int) {
	wiz:
		goto wiz
	}(0)
}
`),
			from: "main.f::foo", to: "bar",
			want: `renaming this label "foo" to "bar".*` +
				`would conflict with this one`,
		},
		{
			from: "main.f::foo", to: "wiz", want: "OK",
		},
		{
			from: "main.f::wiz", to: "x", want: "OK",
		},
		{
			from: "main.f::x", to: "wiz", want: "OK",
		},
		{
			from: "main.f::wiz", to: "foo", want: "OK",
		},

		// Struct fields
		{
			ctxt: main(`
package main

type U struct { u int }
type V struct { v int }

func (V) x() {}

type W (struct {
	U
	V
	w int
})

func f() {
	var w W
	print(w.u) // NB: there is no selection of w.v
	var _ struct { yy, zz int }
}
`),
			// field/field conflict in named struct declaration
			from: "(main.W).U", to: "w",
			want: `renaming this field "U" to "w".*` +
				`would conflict with this field`,
		},
		{
			// rename type used as embedded field
			// => rename field
			// => field/field conflict
			// This is an entailed renaming;
			// it would be nice if we checked source positions.
			from: "main.U", to: "w",
			want: `renaming this field "U" to "w".*` +
				`would conflict with this field`,
		},
		{
			// field/field conflict in unnamed struct declaration
			from: "main.f::zz", to: "yy",
			want: `renaming this field "zz" to "yy".*` +
				`would conflict with this field`,
		},

		// Now we test both directions of (u,v) (u,w) (v,w) (u,x) (v,x).
		// Too bad we don't test position info...
		{
			// field/field ambiguity at same promotion level ('from' selection)
			from: "(main.U).u", to: "v",
			want: `renaming this field "u" to "v".*` +
				`would make this reference ambiguous.*` +
				`with this field`,
		},
		{
			// field/field ambiguity at same promotion level ('to' selection)
			from: "(main.V).v", to: "u",
			want: `renaming this field "v" to "u".*` +
				`would make this reference ambiguous.*` +
				`with this field`,
		},
		{
			// field/method conflict at different promotion level ('from' selection)
			from: "(main.U).u", to: "w",
			want: `renaming this field "u" to "w".*` +
				`would change the referent of this selection.*` +
				`of this field`,
		},
		{
			// field/field shadowing at different promotion levels ('to' selection)
			from: "(main.W).w", to: "u",
			want: `renaming this field "w" to "u".*` +
				`would shadow this selection.*` +
				`of the field declared here`,
		},
		{
			from: "(main.V).v", to: "w",
			want: "OK", // since no selections are made ambiguous
		},
		{
			from: "(main.W).w", to: "v",
			want: "OK", // since no selections are made ambiguous
		},
		{
			// field/method ambiguity at same promotion level ('from' selection)
			from: "(main.U).u", to: "x",
			want: `renaming this field "u" to "x".*` +
				`would make this reference ambiguous.*` +
				`with this method`,
		},
		{
			// field/field ambiguity at same promotion level ('to' selection)
			from: "(main.V).x", to: "u",
			want: `renaming this method "x" to "u".*` +
				`would make this reference ambiguous.*` +
				`with this field`,
		},
		{
			// field/method conflict at named struct declaration
			from: "(main.V).v", to: "x",
			want: `renaming this field "v" to "x".*` +
				`would conflict with this method`,
		},
		{
			// field/method conflict at named struct declaration
			from: "(main.V).x", to: "v",
			want: `renaming this method "x" to "v".*` +
				`would conflict with this field`,
		},

		// Methods
		{
			ctxt: main(`
package main
type C int
func (C) f()
func (C) g()
type D int
func (*D) f()
func (*D) g()
type I interface { f(); g() }
type J interface { I; h() }
var _ I = new(D)
var _ interface {f()} = C(0)
`),
			from: "(main.I).f", to: "g",
			want: `renaming this interface method "f" to "g".*` +
				`would conflict with this method`,
		},
		{
			from: `("main".I).f`, to: "h", // NB: exercises quoted import paths too
			want: `renaming this interface method "f" to "h".*` +
				`would conflict with this method.*` +
				`in named interface type "J"`,
		},
		{
			// type J interface { h; h() } is not a conflict, amusingly.
			from: "main.I", to: "h",
			want: `OK`,
		},
		{
			from: "(main.J).h", to: "f",
			want: `renaming this interface method "h" to "f".*` +
				`would conflict with this method`,
		},
		{
			from: "(main.C).f", to: "e",
			want: `renaming this method "f" to "e".*` +
				`would make main.C no longer assignable to interface{f..}.*` +
				`(rename interface{f..}.f if you intend to change both types)`,
		},
		{
			from: "(main.D).g", to: "e",
			want: `renaming this method "g" to "e".*` +
				`would make \*main.D no longer assignable to interface I.*` +
				`(rename main.I.g if you intend to change both types)`,
		},
		{
			from: "(main.I).f", to: "e",
			want: `OK`,
		},
		// Indirect C/I method coupling via another concrete type D.
		{
			ctxt: main(`
package main
type I interface { f() }
type C int
func (C) f()
type D struct{C}
var _ I = D{}
`),
			from: "(main.C).f", to: "F",
			want: `renaming this method "f" to "F".*` +
				`would make main.D no longer assignable to interface I.*` +
				`(rename main.I.f if you intend to change both types)`,
		},
		// Renaming causes promoted method to become shadowed; C no longer satisfies I.
		{
			ctxt: main(`
package main
type I interface { f() }
type C struct { I }
func (C) g() int
var _ I = C{}
`),
			from: "main.I.f", to: "g",
			want: `renaming this method "f" to "g".*` +
				`would change the g method of main.C invoked via interface main.I.*` +
				`from \(main.I\).g.*` +
				`to \(main.C\).g`,
		},
		// Renaming causes promoted method to become ambiguous; C no longer satisfies I.
		{
			ctxt: main(`
package main
type I interface{f()}
type C int
func (C) f()
type D int
func (D) g()
type E struct{C;D}
var _ I = E{}
`),
			from: "main.I.f", to: "g",
			want: `renaming this method "f" to "g".*` +
				`would make the g method of main.E invoked via interface main.I ambiguous.*` +
				`with \(main.D\).g`,
		},
	} {
		var conflicts []string
		reportError = func(posn token.Position, message string) {
			conflicts = append(conflicts, message)
		}
		if test.ctxt != nil {
			ctxt = test.ctxt
		}
		err := Main(ctxt, test.offset, test.from, test.to)
		var prefix string
		if test.offset == "" {
			prefix = fmt.Sprintf("-from %q -to %q", test.from, test.to)
		} else {
			prefix = fmt.Sprintf("-offset %q -to %q", test.offset, test.to)
		}
		if err == ConflictError {
			got := strings.Join(conflicts, "\n")
			if false {
				t.Logf("%s: %s", prefix, got)
			}
			pattern := "(?s:" + test.want + ")" // enable multi-line matching
			if !regexp.MustCompile(pattern).MatchString(got) {
				t.Errorf("%s: conflict does not match pattern:\n"+
					"Conflict:\t%s\n"+
					"Pattern: %s",
					prefix, got, test.want)
			}
		} else if err != nil {
			t.Errorf("%s: unexpected error: %s", prefix, err)
		} else if test.want != "OK" {
			t.Errorf("%s: unexpected success, want conflicts matching:\n%s",
				prefix, test.want)
		}
	}
}

func TestInvalidIdentifiers(t *testing.T) {
	ctxt := fakeContext(map[string][]string{
		"main": {`
package main

func f() { }
`}})

	for _, test := range []struct {
		from, to string // values of the -offset/-from and -to flags
		want     string // expected error message
	}{
		{
			from: "main.f", to: "_",
			want: `-to "_": not a valid identifier`,
		},
		{
			from: "main.f", to: "123",
			want: `-to "123": not a valid identifier`,
		},
		{
			from: "main.f", to: "for",
			want: `-to "for": not a valid identifier`,
		},
		{
			from: "switch", to: "v",
			want: `-from "switch": invalid expression`,
		},
	} {
		err := Main(ctxt, "", test.from, test.to)
		prefix := fmt.Sprintf("-from %q -to %q", test.from, test.to)
		if err == nil {
			t.Errorf("%s: expected error %q", prefix, test.want)
		} else if err.Error() != test.want {
			t.Errorf("%s: unexpected error\nwant: %s\n got: %s", prefix, test.want, err.Error())
		}
	}
}

func TestRewrites(t *testing.T) {
	defer func(savedWriteFile func(string, []byte) error) {
		writeFile = savedWriteFile
	}(writeFile)

	var ctxt *build.Context
	for _, test := range []struct {
		ctxt             *build.Context    // nil => use previous
		offset, from, to string            // values of the -from/-offset and -to flags
		want             map[string]string // contents of updated files
		alias            bool              // requires materialized aliases
	}{
		// Elimination of renaming import.
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import foo2 "foo"

var _ foo2.T
`},
			}),
			from: "main::foo2", to: "foo",
			want: map[string]string{
				"/go/src/main/0.go": `package main

import "foo"

var _ foo.T
`,
			},
		},
		// Introduction of renaming import.
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

var _ foo.T
`},
			}),
			offset: "/go/src/main/0.go:#36", to: "foo2", // the "foo" in foo.T
			want: map[string]string{
				"/go/src/main/0.go": `package main

import foo2 "foo"

var _ foo2.T
`,
			},
		},
		// Renaming of package-level member.
		{
			from: "foo.T", to: "U",
			want: map[string]string{
				"/go/src/main/0.go": `package main

import "foo"

var _ foo.U
`,
				"/go/src/foo/0.go": `package foo

type U int
`,
			},
		},
		// Rename package-level func plus doc
		{
			ctxt: main(`package main

// Foo is a no-op.
// Calling Foo does nothing.
func Foo() {
}
`),
			from: "main.Foo", to: "FooBar",
			want: map[string]string{
				"/go/src/main/0.go": `package main

// FooBar is a no-op.
// Calling FooBar does nothing.
func FooBar() {
}
`,
			},
		},
		// Rename method plus doc
		{
			ctxt: main(`package main

type Foo struct{}

// Bar does nothing.
func (Foo) Bar() {
}
`),
			from: "main.Foo.Bar", to: "Baz",
			want: map[string]string{
				"/go/src/main/0.go": `package main

type Foo struct{}

// Baz does nothing.
func (Foo) Baz() {
}
`,
			},
		},
		// Rename type spec plus doc
		{
			ctxt: main(`package main

type (
	// Test but not Testing.
	Test struct{}
)
`),
			from: "main.Test", to: "Type",
			want: map[string]string{
				"/go/src/main/0.go": `package main

type (
	// Type but not Testing.
	Type struct{}
)
`,
			},
		},
		// Rename type in gen decl plus doc
		{
			ctxt: main(`package main

// T is a test type.
type T struct{}
`),
			from: "main.T", to: "Type",
			want: map[string]string{
				"/go/src/main/0.go": `package main

// Type is a test type.
type Type struct{}
`,
			},
		},
		// Rename value spec with doc
		{
			ctxt: main(`package main

const (
	// C is the speed of light.
	C = 2.998e8
)
`),
			from: "main.C", to: "Lightspeed",
			want: map[string]string{
				"/go/src/main/0.go": `package main

const (
	// Lightspeed is the speed of light.
	Lightspeed = 2.998e8
)
`,
			},
		},
		// Rename value inside gen decl with doc
		{
			ctxt: main(`package main

var out *string
`),
			from: "main.out", to: "discard",
			want: map[string]string{
				"/go/src/main/0.go": `package main

var discard *string
`,
			},
		},
		// Rename field plus doc
		{
			ctxt: main(`package main

type Struct struct {
	// Field is a struct field.
	Field string
}
`),
			from: "main.Struct.Field", to: "Foo",
			want: map[string]string{
				"/go/src/main/0.go": `package main

type Struct struct {
	// Foo is a struct field.
	Foo string
}
`,
			},
		},
		// Label renamings.
		{
			ctxt: main(`package main
func f() {
loop:
	loop := 0
	go func() {
	loop:
		goto loop
	}()
	loop++
	goto loop
}
`),
			offset: "/go/src/main/0.go:#25", to: "loop2", // def of outer label "loop"
			want: map[string]string{
				"/go/src/main/0.go": `package main

func f() {
loop2:
	loop := 0
	go func() {
	loop:
		goto loop
	}()
	loop++
	goto loop2
}
`,
			},
		},
		{
			offset: "/go/src/main/0.go:#70", to: "loop2", // ref to inner label "loop"
			want: map[string]string{
				"/go/src/main/0.go": `package main

func f() {
loop:
	loop := 0
	go func() {
	loop2:
		goto loop2
	}()
	loop++
	goto loop
}
`,
			},
		},
		// Renaming of type used as embedded field.
		{
			ctxt: main(`package main

type T int
type U struct { T }

var _ = U{}.T
`),
			from: "main.T", to: "T2",
			want: map[string]string{
				"/go/src/main/0.go": `package main

type T2 int
type U struct{ T2 }

var _ = U{}.T2
`,
			},
		},
		// Renaming of embedded field.
		{
			ctxt: main(`package main

type T int
type U struct { T }

var _ = U{}.T
`),
			offset: "/go/src/main/0.go:#58", to: "T2", // T in "U{}.T"
			want: map[string]string{
				"/go/src/main/0.go": `package main

type T2 int
type U struct{ T2 }

var _ = U{}.T2
`,
			},
		},
		// Renaming of pointer embedded field.
		{
			ctxt: main(`package main

type T int
type U struct { *T }

var _ = U{}.T
`),
			offset: "/go/src/main/0.go:#59", to: "T2", // T in "U{}.T"
			want: map[string]string{
				"/go/src/main/0.go": `package main

type T2 int
type U struct{ *T2 }

var _ = U{}.T2
`,
			},
		},
		// Renaming of embedded field alias.
		{
			alias: true,
			ctxt: main(`package main

type T int
type A = T
type U struct{ A }

var _ = U{}.A
var a A
`),
			offset: "/go/src/main/0.go:#68", to: "A2", // A in "U{}.A"
			want: map[string]string{
				"/go/src/main/0.go": `package main

type T int
type A2 = T
type U struct{ A2 }

var _ = U{}.A2
var a A2
`,
			},
		},
		// Renaming of embedded field pointer to alias.
		{
			alias: true,
			ctxt: main(`package main

type T int
type A = T
type U struct{ *A }

var _ = U{}.A
var a A
`),
			offset: "/go/src/main/0.go:#69", to: "A2", // A in "U{}.A"
			want: map[string]string{
				"/go/src/main/0.go": `package main

type T int
type A2 = T
type U struct{ *A2 }

var _ = U{}.A2
var a A2
`,
			},
		},
		// Renaming of alias
		{
			ctxt: main(`package main

type A = int

func _() A {
	return A(0)
}
`),
			offset: "/go/src/main/0.go:#49", to: "A2", // A in "A(0)"
			want: map[string]string{
				"/go/src/main/0.go": `package main

type A2 = int

func _() A2 {
	return A2(0)
}
`,
			},
		},

		// Lexical scope tests.
		{
			ctxt: main(`package main

var y int

func f() {
	print(y)
	y := ""
	print(y)
}
`),
			from: "main.y", to: "x",
			want: map[string]string{
				"/go/src/main/0.go": `package main

var x int

func f() {
	print(x)
	y := ""
	print(y)
}
`,
			},
		},
		{
			from: "main.f::y", to: "x",
			want: map[string]string{
				"/go/src/main/0.go": `package main

var y int

func f() {
	print(y)
	x := ""
	print(x)
}
`,
			},
		},
		// Renaming of typeswitch vars (a corner case).
		{
			ctxt: main(`package main

func f(z interface{}) {
	switch y := z.(type) {
	case int:
		print(y)
	default:
		print(y)
	}
}
`),
			offset: "/go/src/main/0.go:#46", to: "x", // def of y
			want: map[string]string{
				"/go/src/main/0.go": `package main

func f(z interface{}) {
	switch x := z.(type) {
	case int:
		print(x)
	default:
		print(x)
	}
}
`},
		},
		{
			offset: "/go/src/main/0.go:#81", to: "x", // ref of y in case int
			want: map[string]string{
				"/go/src/main/0.go": `package main

func f(z interface{}) {
	switch x := z.(type) {
	case int:
		print(x)
	default:
		print(x)
	}
}
`},
		},
		{
			offset: "/go/src/main/0.go:#102", to: "x", // ref of y in default case
			want: map[string]string{
				"/go/src/main/0.go": `package main

func f(z interface{}) {
	switch x := z.(type) {
	case int:
		print(x)
	default:
		print(x)
	}
}
`},
		},

		// Renaming of embedded field that is a qualified reference.
		// (Regression test for bug 8924.)
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

type _ struct{ *foo.T }
`},
			}),
			offset: "/go/src/main/0.go:#48", to: "U", // the "T" in *foo.T
			want: map[string]string{
				"/go/src/foo/0.go": `package foo

type U int
`,
				"/go/src/main/0.go": `package main

import "foo"

type _ struct{ *foo.U }
`,
			},
		},

		// Renaming of embedded field that is a qualified reference with the '-from' flag.
		// (Regression test for bug 12038.)
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

type V struct{ *foo.T }
`},
			}),
			from: "(main.V).T", to: "U", // the "T" in *foo.T
			want: map[string]string{
				"/go/src/foo/0.go": `package foo

type U int
`,
				"/go/src/main/0.go": `package main

import "foo"

type V struct{ *foo.U }
`,
			},
		},
		{
			ctxt: fakeContext(map[string][]string{
				"foo": {`package foo; type T int`},
				"main": {`package main

import "foo"

type V struct{ foo.T }
`},
			}),
			from: "(main.V).T", to: "U", // the "T" in *foo.T
			want: map[string]string{
				"/go/src/foo/0.go": `package foo

type U int
`,
				"/go/src/main/0.go": `package main

import "foo"

type V struct{ foo.U }
`,
			},
		},

		// Interface method renaming.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`
package main
type I interface {
	f()
}
type J interface { f(); g() }
type A int
func (A) f()
type B int
func (B) f()
func (B) g()
type C int
func (C) f()
func (C) g()
var _, _ I = A(0), B(0)
var _, _ J = B(0), C(0)
`,
				},
			}),
			offset: "/go/src/main/0.go:#34", to: "F", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	F()
}
type J interface {
	F()
	g()
}
type A int

func (A) F()

type B int

func (B) F()
func (B) g()

type C int

func (C) F()
func (C) g()

var _, _ I = A(0), B(0)
var _, _ J = B(0), C(0)
`,
			},
		},
		{
			offset: "/go/src/main/0.go:#59", to: "F", // abstract method J.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	F()
}
type J interface {
	F()
	g()
}
type A int

func (A) F()

type B int

func (B) F()
func (B) g()

type C int

func (C) F()
func (C) g()

var _, _ I = A(0), B(0)
var _, _ J = B(0), C(0)
`,
			},
		},
		{
			offset: "/go/src/main/0.go:#64", to: "G", // abstract method J.g
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	f()
}
type J interface {
	f()
	G()
}
type A int

func (A) f()

type B int

func (B) f()
func (B) G()

type C int

func (C) f()
func (C) G()

var _, _ I = A(0), B(0)
var _, _ J = B(0), C(0)
`,
			},
		},
		// Indirect coupling of I.f to C.f from D->I assignment and anonymous field of D.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`
package main
type I interface {
	f()
}
type C int
func (C) f()
type D struct{C}
var _ I = D{}
`,
				},
			}),
			offset: "/go/src/main/0.go:#34", to: "F", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	F()
}
type C int

func (C) F()

type D struct{ C }

var _ I = D{}
`,
			},
		},
		// Interface embedded in struct.  No conflict if C need not satisfy I.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`
package main
type I interface {
	f()
}
type C struct{I}
func (C) g() int
var _ int = C{}.g()
`,
				},
			}),
			offset: "/go/src/main/0.go:#34", to: "g", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	g()
}
type C struct{ I }

func (C) g() int

var _ int = C{}.g()
`,
			},
		},
		// A type assertion causes method coupling iff signatures match.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`package main
type I interface{
	f()
}
type J interface{
	f()
}
var _ = I(nil).(J)
`,
				},
			}),
			offset: "/go/src/main/0.go:#32", to: "g", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	g()
}
type J interface {
	g()
}

var _ = I(nil).(J)
`,
			},
		},
		// Impossible type assertion: no method coupling.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`package main
type I interface{
	f()
}
type J interface{
	f()int
}
var _ = I(nil).(J)
`,
				},
			}),
			offset: "/go/src/main/0.go:#32", to: "g", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	g()
}
type J interface {
	f() int
}

var _ = I(nil).(J)
`,
			},
		},
		// Impossible type assertion: no method coupling C.f<->J.f.
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`package main
type I interface{
	f()
}
type C int
func (C) f()
type J interface{
	f()int
}
var _ = I(C(0)).(J)
`,
				},
			}),
			offset: "/go/src/main/0.go:#32", to: "g", // abstract method I.f
			want: map[string]string{
				"/go/src/main/0.go": `package main

type I interface {
	g()
}
type C int

func (C) g()

type J interface {
	f() int
}

var _ = I(C(0)).(J)
`,
			},
		},
		// Progress after "soft" type errors (Go issue 14596).
		{
			ctxt: fakeContext(map[string][]string{
				"main": {`package main

func main() {
	var unused, x int
	print(x)
}
`,
				},
			}),
			offset: "/go/src/main/0.go:#54", to: "y", // var x
			want: map[string]string{
				"/go/src/main/0.go": `package main

func main() {
	var unused, y int
	print(y)
}
`,
			},
		},
	} {
		if test.ctxt != nil {
			ctxt = test.ctxt
		}

		got := make(map[string]string)
		writeFile = func(filename string, content []byte) error {
			got[filepath.ToSlash(filename)] = string(content)
			return nil
		}

		err := Main(ctxt, test.offset, test.from, test.to)
		var prefix string
		if test.offset == "" {
			prefix = fmt.Sprintf("-from %q -to %q", test.from, test.to)
		} else {
			prefix = fmt.Sprintf("-offset %q -to %q", test.offset, test.to)
		}
		if err != nil {
			t.Errorf("%s: unexpected error: %s", prefix, err)
			continue
		}

		for file, wantContent := range test.want {
			gotContent, ok := got[file]
			delete(got, file)
			if !ok {
				t.Errorf("%s: file %s not rewritten", prefix, file)
				continue
			}
			if gotContent != wantContent {
				t.Errorf("%s: rewritten file %s does not match expectation; got <<<%s>>>\n"+
					"want <<<%s>>>", prefix, file, gotContent, wantContent)
			}
		}
		// got should now be empty
		for file := range got {
			t.Errorf("%s: unexpected rewrite of file %s", prefix, file)
		}
	}
}

func TestDiff(t *testing.T) {
	switch runtime.GOOS {
	case "windows":
		if os.Getenv("GO_BUILDER_NAME") != "" {
			if _, err := exec.LookPath(DiffCmd); err != nil {
				t.Skipf("diff tool non-existent for %s on builders", runtime.GOOS)
			}
		}
	case "plan9":
		t.Skipf("plan9 diff tool doesn't support -u flag")
	}
	testenv.NeedsTool(t, DiffCmd)
	testenv.NeedsTool(t, "go") // to locate the package to be renamed

	defer func() {
		Diff = false
		stdout = os.Stdout
	}()
	Diff = true
	stdout = new(bytes.Buffer)

	// Set up a fake GOPATH in a temporary directory,
	// and ensure we're in GOPATH mode.
	tmpdir, err := os.MkdirTemp("", "TestDiff")
	if err != nil {
		t.Fatal(err)
	}
	defer os.RemoveAll(tmpdir)
	buildCtx := build.Default
	buildCtx.GOPATH = tmpdir

	pkgDir := filepath.Join(tmpdir, "src", "example.com", "rename")
	if err := os.MkdirAll(pkgDir, 0777); err != nil {
		t.Fatal(err)
	}

	prevWD, err := os.Getwd()
	if err != nil {
		t.Fatal(err)
	}
	defer os.Chdir(prevWD)

	if err := os.Chdir(pkgDir); err != nil {
		t.Fatal(err)
	}

	const modFile = `module example.com/rename

go 1.15
`
	if err := os.WriteFile(filepath.Join(pkgDir, "go.mod"), []byte(modFile), 0644); err != nil {
		t.Fatal(err)
	}

	const goFile = `package rename

func justHereForTestingDiff() {
	justHereForTestingDiff()
}
`
	if err := os.WriteFile(filepath.Join(pkgDir, "rename_test.go"), []byte(goFile), 0644); err != nil {
		t.Fatal(err)
	}

	if err := Main(&buildCtx, "", `"example.com/rename".justHereForTestingDiff`, "Foo"); err != nil {
		t.Fatal(err)
	}

	// NB: there are tabs in the string literal!
	if !strings.Contains(stdout.(fmt.Stringer).String(), `
-func justHereForTestingDiff() {
-	justHereForTestingDiff()
+func Foo() {
+	Foo()
 }
`) {
		t.Errorf("unexpected diff:\n<<%s>>", stdout)
	}
}

// ---------------------------------------------------------------------

// Simplifying wrapper around buildutil.FakeContext for packages whose
// filenames are sequentially numbered (%d.go).  pkgs maps a package
// import path to its list of file contents.
func fakeContext(pkgs map[string][]string) *build.Context {
	pkgs2 := make(map[string]map[string]string)
	for path, files := range pkgs {
		filemap := make(map[string]string)
		for i, contents := range files {
			filemap[fmt.Sprintf("%d.go", i)] = contents
		}
		pkgs2[path] = filemap
	}
	return buildutil.FakeContext(pkgs2)
}

// helper for single-file main packages with no imports.
func main(content string) *build.Context {
	return fakeContext(map[string][]string{"main": {content}})
}


================================================
FILE: refactor/rename/spec.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rename

// This file contains logic related to specifying a renaming: parsing of
// the flags as a form of query, and finding the object(s) it denotes.
// See Usage for flag details.

import (
	"bytes"
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/token"
	"go/types"
	"log"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"golang.org/x/tools/go/buildutil"
	"golang.org/x/tools/go/loader"
	"golang.org/x/tools/internal/typesinternal"
)

// A spec specifies an entity to rename.
//
// It is populated from an -offset flag or -from query;
// see Usage for the allowed -from query forms.
type spec struct {
	// pkg is the package containing the position
	// specified by the -from or -offset flag.
	// If filename == "", our search for the 'from' entity
	// is restricted to this package.
	pkg string

	// The original name of the entity being renamed.
	// If the query had a ::from component, this is that;
	// otherwise it's the last segment, e.g.
	//   (encoding/json.Decoder).from
	//   encoding/json.from
	fromName string

	// -- The remaining fields are private to this file.  All are optional. --

	// The query's ::x suffix, if any.
	searchFor string

	// e.g. "Decoder" in "(encoding/json.Decoder).fieldOrMethod"
	//                or "encoding/json.Decoder
	pkgMember string

	// e.g. fieldOrMethod in "(encoding/json.Decoder).fieldOrMethod"
	typeMember string

	// Restricts the query to this file.
	// Implied by -from="file.go::x" and -offset flags.
	filename string

	// Byte offset of the 'from' identifier within the file named 'filename'.
	// -offset mode only.
	offset int
}

// parseFromFlag interprets the "-from" flag value as a renaming specification.
// See Usage in rename.go for valid formats.
func parseFromFlag(ctxt *build.Context, fromFlag string) (*spec, error) {
	var spec spec
	var main string // sans "::x" suffix
	switch parts := strings.Split(fromFlag, "::"); len(parts) {
	case 1:
		main = parts[0]
	case 2:
		main = parts[0]
		spec.searchFor = parts[1]
		if parts[1] == "" {
			// error
		}
	default:
		return nil, fmt.Errorf("-from %q: invalid identifier specification (see -help for formats)", fromFlag)
	}

	if strings.HasSuffix(main, ".go") {
		// main is "filename.go"
		if spec.searchFor == "" {
			return nil, fmt.Errorf("-from: filename %q must have a ::name suffix", main)
		}
		spec.filename = main
		if !buildutil.FileExists(ctxt, spec.filename) {
			return nil, fmt.Errorf("no such file: %s", spec.filename)
		}

		bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename)
		if err != nil {
			return nil, err
		}
		spec.pkg = bp.ImportPath

	} else {
		// main is one of:
		//  "importpath"
		//  "importpath".member
		//  (*"importpath".type).fieldormethod           (parens and star optional)
		if err := parseObjectSpec(&spec, main); err != nil {
			return nil, err
		}
	}

	if spec.searchFor != "" {
		spec.fromName = spec.searchFor
	}

	cwd, err := os.Getwd()
	if err != nil {
		return nil, err
	}

	// Sanitize the package.
	bp, err := ctxt.Import(spec.pkg, cwd, build.FindOnly)
	if err != nil {
		return nil, fmt.Errorf("can't find package %q", spec.pkg)
	}
	spec.pkg = bp.ImportPath

	if !isValidIdentifier(spec.fromName) {
		return nil, fmt.Errorf("-from: invalid identifier %q", spec.fromName)
	}

	if Verbose {
		log.Printf("-from spec: %+v", spec)
	}

	return &spec, nil
}

// parseObjectSpec parses main as one of the non-filename forms of
// object specification.
func parseObjectSpec(spec *spec, main string) error {
	// Parse main as a Go expression, albeit a strange one.
	e, _ := parser.ParseExpr(main)

	if pkg := parseImportPath(e); pkg != "" {
		// e.g. bytes or "encoding/json": a package
		spec.pkg = pkg
		if spec.searchFor == "" {
			return fmt.Errorf("-from %q: package import path %q must have a ::name suffix",
				main, main)
		}
		return nil
	}

	if e, ok := e.(*ast.SelectorExpr); ok {
		x := ast.Unparen(e.X)

		// Strip off star constructor, if any.
		if star, ok := x.(*ast.StarExpr); ok {
			x = star.X
		}

		if pkg := parseImportPath(x); pkg != "" {
			// package member e.g. "encoding/json".HTMLEscape
			spec.pkg = pkg              // e.g. "encoding/json"
			spec.pkgMember = e.Sel.Name // e.g. "HTMLEscape"
			spec.fromName = e.Sel.Name
			return nil
		}

		if x, ok := x.(*ast.SelectorExpr); ok {
			// field/method of type e.g. ("encoding/json".Decoder).Decode
			y := ast.Unparen(x.X)
			if pkg := parseImportPath(y); pkg != "" {
				spec.pkg = pkg               // e.g. "encoding/json"
				spec.pkgMember = x.Sel.Name  // e.g. "Decoder"
				spec.typeMember = e.Sel.Name // e.g. "Decode"
				spec.fromName = e.Sel.Name
				return nil
			}
		}
	}

	return fmt.Errorf("-from %q: invalid expression", main)
}

// parseImportPath returns the import path of the package denoted by e.
// Any import path may be represented as a string literal;
// single-segment import paths (e.g. "bytes") may also be represented as
// ast.Ident.  parseImportPath returns "" for all other expressions.
func parseImportPath(e ast.Expr) string {
	switch e := e.(type) {
	case *ast.Ident:
		return e.Name // e.g. bytes

	case *ast.BasicLit:
		if e.Kind == token.STRING {
			pkgname, _ := strconv.Unquote(e.Value)
			return pkgname // e.g. "encoding/json"
		}
	}
	return ""
}

// parseOffsetFlag interprets the "-offset" flag value as a renaming specification.
func parseOffsetFlag(ctxt *build.Context, offsetFlag string) (*spec, error) {
	var spec spec
	// Validate -offset, e.g. file.go:#123
	parts := strings.Split(offsetFlag, ":#")
	if len(parts) != 2 {
		return nil, fmt.Errorf("-offset %q: invalid offset specification", offsetFlag)
	}

	spec.filename = parts[0]
	if !buildutil.FileExists(ctxt, spec.filename) {
		return nil, fmt.Errorf("no such file: %s", spec.filename)
	}

	bp, err := buildutil.ContainingPackage(ctxt, wd, spec.filename)
	if err != nil {
		return nil, err
	}
	spec.pkg = bp.ImportPath

	for _, r := range parts[1] {
		if !isDigit(r) {
			return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag)
		}
	}
	spec.offset, err = strconv.Atoi(parts[1])
	if err != nil {
		return nil, fmt.Errorf("-offset %q: non-numeric offset", offsetFlag)
	}

	// Parse the file and check there's an identifier at that offset.
	fset := token.NewFileSet()
	f, err := buildutil.ParseFile(fset, ctxt, nil, wd, spec.filename, parser.ParseComments)
	if err != nil {
		return nil, fmt.Errorf("-offset %q: cannot parse file: %s", offsetFlag, err)
	}

	id := identAtOffset(fset, f, spec.offset)
	if id == nil {
		return nil, fmt.Errorf("-offset %q: no identifier at this position", offsetFlag)
	}

	spec.fromName = id.Name

	return &spec, nil
}

var wd = func() string {
	wd, err := os.Getwd()
	if err != nil {
		panic("cannot get working directory: " + err.Error())
	}
	return wd
}()

// For source trees built with 'go build', the -from or -offset
// spec identifies exactly one initial 'from' object to rename,
// but certain proprietary build systems allow a single file to
// appear in multiple packages (e.g. the test package contains a
// copy of its library), so there may be multiple objects for
// the same source entity.

func findFromObjects(iprog *loader.Program, spec *spec) ([]types.Object, error) {
	if spec.filename != "" {
		return findFromObjectsInFile(iprog, spec)
	}

	// Search for objects defined in specified package.

	// TODO(adonovan): the iprog.ImportMap has an entry {"main": ...}
	// for main packages, even though that's not an import path.
	// Seems like a bug.
	//
	// pkg := iprog.ImportMap[spec.pkg]
	// if pkg == nil {
	// 	return fmt.Errorf("cannot find package %s", spec.pkg) // can't happen?
	// }
	// info := iprog.AllPackages[pkg]

	// Workaround: lookup by value.
	var info *loader.PackageInfo
	var pkg *types.Package
	for pkg, info = range iprog.AllPackages {
		if pkg.Path() == spec.pkg {
			break
		}
	}
	if info == nil {
		return nil, fmt.Errorf("package %q was not loaded", spec.pkg)
	}

	objects, err := findObjects(info, spec)
	if err != nil {
		return nil, err
	}
	if len(objects) > 1 {
		// ambiguous "*" scope query
		return nil, ambiguityError(iprog.Fset, objects)
	}
	return objects, nil
}

func findFromObjectsInFile(iprog *loader.Program, spec *spec) ([]types.Object, error) {
	var fromObjects []types.Object
	for _, info := range iprog.AllPackages {
		// restrict to specified filename
		// NB: under certain proprietary build systems, a given
		// filename may appear in multiple packages.
		for _, f := range info.Files {
			thisFile := iprog.Fset.File(f.FileStart)
			if !sameFile(thisFile.Name(), spec.filename) {
				continue
			}
			// This package contains the query file.

			if spec.offset != 0 {
				// We cannot refactor generated files since position information is invalidated.
				if ast.IsGenerated(f) {
					return nil, fmt.Errorf("cannot rename identifiers in generated file containing DO NOT EDIT marker: %s", thisFile.Name())
				}

				// Search for a specific ident by file/offset.
				id := identAtOffset(iprog.Fset, f, spec.offset)
				if id == nil {
					// can't happen?
					return nil, fmt.Errorf("identifier not found")
				}
				obj := info.Uses[id]
				if obj == nil {
					obj = info.Defs[id]
					if obj == nil {
						// Ident without Object.

						// Package clause?
						pos := thisFile.Pos(spec.offset)
						_, path, _ := iprog.PathEnclosingInterval(pos, pos)
						if len(path) == 2 { // [Ident File]
							// TODO(adonovan): support this case.
							return nil, fmt.Errorf("cannot rename %q: renaming package clauses is not yet supported",
								path[1].(*ast.File).Name.Name)
						}

						// Implicit y in "switch y := x.(type) {"?
						if obj := typeSwitchVar(&info.Info, path); obj != nil {
							return []types.Object{obj}, nil
						}

						// Probably a type error.
						return nil, fmt.Errorf("cannot find object for %q", id.Name)
					}
				}
				if obj.Pkg() == nil {
					return nil, fmt.Errorf("cannot rename predeclared identifiers (%s)", obj)

				}

				fromObjects = append(fromObjects, obj)
			} else {
				// do a package-wide query
				objects, err := findObjects(info, spec)
				if err != nil {
					return nil, err
				}

				// filter results: only objects defined in thisFile
				var filtered []types.Object
				for _, obj := range objects {
					if iprog.Fset.File(obj.Pos()) == thisFile {
						filtered = append(filtered, obj)
					}
				}
				if len(filtered) == 0 {
					return nil, fmt.Errorf("no object %q declared in file %s",
						spec.fromName, spec.filename)
				} else if len(filtered) > 1 {
					return nil, ambiguityError(iprog.Fset, filtered)
				}
				fromObjects = append(fromObjects, filtered[0])
			}
			break
		}
	}
	if len(fromObjects) == 0 {
		// can't happen?
		return nil, fmt.Errorf("file %s was not part of the loaded program", spec.filename)
	}
	return fromObjects, nil
}

func typeSwitchVar(info *types.Info, path []ast.Node) types.Object {
	if len(path) > 3 {
		// [Ident AssignStmt TypeSwitchStmt...]
		if sw, ok := path[2].(*ast.TypeSwitchStmt); ok {
			// choose the first case.
			if len(sw.Body.List) > 0 {
				obj := info.Implicits[sw.Body.List[0].(*ast.CaseClause)]
				if obj != nil {
					return obj
				}
			}
		}
	}
	return nil
}

// On success, findObjects returns the list of objects named
// spec.fromName matching the spec.  On success, the result has exactly
// one element unless spec.searchFor!="", in which case it has at least one
// element.
func findObjects(info *loader.PackageInfo, spec *spec) ([]types.Object, error) {
	if spec.pkgMember == "" {
		if spec.searchFor == "" {
			panic(spec)
		}
		objects := searchDefs(&info.Info, spec.searchFor)
		if objects == nil {
			return nil, fmt.Errorf("no object %q declared in package %q",
				spec.searchFor, info.Pkg.Path())
		}
		return objects, nil
	}

	pkgMember := info.Pkg.Scope().Lookup(spec.pkgMember)
	if pkgMember == nil {
		return nil, fmt.Errorf("package %q has no member %q",
			info.Pkg.Path(), spec.pkgMember)
	}

	var searchFunc *types.Func
	if spec.typeMember == "" {
		// package member
		if spec.searchFor == "" {
			return []types.Object{pkgMember}, nil
		}

		// Search within pkgMember, which must be a function.
		searchFunc, _ = pkgMember.(*types.Func)
		if searchFunc == nil {
			return nil, fmt.Errorf("cannot search for %q within %s %q",
				spec.searchFor, objectKind(pkgMember), pkgMember)
		}
	} else {
		// field/method of type
		// e.g. (encoding/json.Decoder).Decode
		// or ::x within it.

		tName, _ := pkgMember.(*types.TypeName)
		if tName == nil {
			return nil, fmt.Errorf("%s.%s is a %s, not a type",
				info.Pkg.Path(), pkgMember.Name(), objectKind(pkgMember))
		}

		// search within named type.
		obj, _, _ := types.LookupFieldOrMethod(tName.Type(), true, info.Pkg, spec.typeMember)
		if obj == nil {
			return nil, fmt.Errorf("cannot find field or method %q of %s.%s",
				spec.typeMember, info.Pkg.Path(), tName.Name())
		}

		if spec.searchFor == "" {
			// If it is an embedded field (*Named or *Alias),
			// return the type of the field.
			if v, ok := obj.(*types.Var); ok && v.Anonymous() {
				if t, ok := typesinternal.Unpointer(v.Type()).(hasTypeName); ok {
					return []types.Object{t.Obj()}, nil
				}
			}
			return []types.Object{obj}, nil
		}

		searchFunc, _ = obj.(*types.Func)
		if searchFunc == nil {
			return nil, fmt.Errorf("cannot search for local name %q within %s (%s.%s).%s; need a function",
				spec.searchFor, objectKind(obj), info.Pkg.Path(), tName.Name(),
				obj.Name())
		}
		if types.IsInterface(tName.Type()) {
			return nil, fmt.Errorf("cannot search for local name %q within abstract method (%s.%s).%s",
				spec.searchFor, info.Pkg.Path(), tName.Name(), searchFunc.Name())
		}
	}

	// -- search within function or method --

	decl := funcDecl(info, searchFunc)
	if decl == nil {
		return nil, fmt.Errorf("cannot find syntax for %s", searchFunc) // can't happen?
	}

	var objects []types.Object
	for _, obj := range searchDefs(&info.Info, spec.searchFor) {
		// We use positions, not scopes, to determine whether
		// the obj is within searchFunc.  This is clumsy, but the
		// alternative, using the types.Scope tree, doesn't
		// account for non-lexical objects like fields and
		// interface methods.
		if decl.Pos() <= obj.Pos() && obj.Pos() < decl.End() && obj != searchFunc {
			objects = append(objects, obj)
		}
	}
	if objects == nil {
		return nil, fmt.Errorf("no local definition of %q within %s",
			spec.searchFor, searchFunc)
	}
	return objects, nil
}

func funcDecl(info *loader.PackageInfo, fn *types.Func) *ast.FuncDecl {
	for _, f := range info.Files {
		for _, d := range f.Decls {
			if d, ok := d.(*ast.FuncDecl); ok && info.Defs[d.Name] == fn {
				return d
			}
		}
	}
	return nil
}

func searchDefs(info *types.Info, name string) []types.Object {
	var objects []types.Object
	for id, obj := range info.Defs {
		if obj == nil {
			// e.g. blank ident.
			// TODO(adonovan): but also implicit y in
			//    switch y := x.(type)
			// Needs some thought.
			continue
		}
		if id.Name == name {
			objects = append(objects, obj)
		}
	}
	return objects
}

func identAtOffset(fset *token.FileSet, f *ast.File, offset int) *ast.Ident {
	var found *ast.Ident
	ast.Inspect(f, func(n ast.Node) bool {
		if id, ok := n.(*ast.Ident); ok {
			idpos := fset.Position(id.Pos()).Offset
			if idpos <= offset && offset < idpos+len(id.Name) {
				found = id
			}
		}
		return found == nil // keep traversing only until found
	})
	return found
}

// ambiguityError returns an error describing an ambiguous "*" scope query.
func ambiguityError(fset *token.FileSet, objects []types.Object) error {
	var buf bytes.Buffer
	for i, obj := range objects {
		if i > 0 {
			buf.WriteString(", ")
		}
		posn := fset.Position(obj.Pos())
		fmt.Fprintf(&buf, "%s at %s:%d:%d",
			objectKind(obj), filepath.Base(posn.Filename), posn.Line, posn.Column)
	}
	return fmt.Errorf("ambiguous specifier %s matches %s",
		objects[0].Name(), buf.String())
}


================================================
FILE: refactor/rename/util.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package rename

import (
	"go/token"
	"go/types"
	"os"
	"path/filepath"
	"reflect"
	"runtime"
	"strings"
	"unicode"
)

func objectKind(obj types.Object) string {
	switch obj := obj.(type) {
	case *types.PkgName:
		return "imported package name"
	case *types.TypeName: // defined type | alias | type parameter
		return "type"
	case *types.Var:
		if obj.IsField() {
			return "field"
		}
	case *types.Func:
		if obj.Signature().Recv() != nil {
			return "method"
		}
	}
	// label, func, var, const
	return strings.ToLower(strings.TrimPrefix(reflect.TypeOf(obj).String(), "*types."))
}

// NB: for renamings, blank is not considered valid.
func isValidIdentifier(id string) bool {
	if id == "" || id == "_" {
		return false
	}
	for i, r := range id {
		if !isLetter(r) && (i == 0 || !isDigit(r)) {
			return false
		}
	}
	return token.Lookup(id) == token.IDENT
}

// isLocal reports whether obj is local to some function.
// Precondition: not a struct field or interface method.
func isLocal(obj types.Object) bool {
	// [... 5=stmt 4=func 3=file 2=pkg 1=universe]
	var depth int
	for scope := obj.Parent(); scope != nil; scope = scope.Parent() {
		depth++
	}
	return depth >= 4
}

// -- Plundered from go/scanner: ---------------------------------------

func isLetter(ch rune) bool {
	return 'a' <= ch && ch <= 'z' || 'A' <= ch && ch <= 'Z' || ch == '_' || ch >= 0x80 && unicode.IsLetter(ch)
}

func isDigit(ch rune) bool {
	return '0' <= ch && ch <= '9' || ch >= 0x80 && unicode.IsDigit(ch)
}

// -- Plundered from golang.org/x/tools/cmd/guru -----------------

// sameFile returns true if x and y have the same basename and denote
// the same file.
func sameFile(x, y string) bool {
	if runtime.GOOS == "windows" {
		x = filepath.ToSlash(x)
		y = filepath.ToSlash(y)
	}
	if x == y {
		return true
	}
	if filepath.Base(x) == filepath.Base(y) { // (optimisation)
		if xi, err := os.Stat(x); err == nil {
			if yi, err := os.Stat(y); err == nil {
				return os.SameFile(xi, yi)
			}
		}
	}
	return false
}

func is[T any](x any) bool {
	_, ok := x.(T)
	return ok
}


================================================
FILE: refactor/satisfy/find.go
================================================
// Copyright 2014 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package satisfy inspects the type-checked ASTs of Go packages and
// reports the set of discovered type constraints of the form (lhs, rhs
// Type) where lhs is a non-trivial interface, rhs satisfies this
// interface, and this fact is necessary for the package to be
// well-typed.
//
// It requires well-typed inputs.
package satisfy // import "golang.org/x/tools/refactor/satisfy"

// NOTES:
//
// We don't care about numeric conversions, so we don't descend into
// types or constant expressions.  This is unsound because
// constant expressions can contain arbitrary statements, e.g.
//   const x = len([1]func(){func() {
//     ...
//   }})
//
// Assignability conversions are possible in the following places:
// - in assignments y = x, y := x, var y = x.
// - from call argument types to formal parameter types
// - in append and delete calls
// - from return operands to result parameter types
// - in composite literal T{k:v}, from k and v to T's field/element/key type
// - in map[key] from key to the map's key type
// - in comparisons x==y and switch x { case y: }.
// - in explicit conversions T(x)
// - in sends ch <- x, from x to the channel element type
// - in type assertions x.(T) and switch x.(type) { case T: }
//
// The results of this pass provide information equivalent to the
// ssa.MakeInterface and ssa.ChangeInterface instructions.

import (
	"fmt"
	"go/ast"
	"go/token"
	"go/types"

	"golang.org/x/tools/go/types/typeutil"
	"golang.org/x/tools/internal/typeparams"
)

// A Constraint records the fact that the RHS type does and must
// satisfy the LHS type, which is an interface.
// The names are suggestive of an assignment statement LHS = RHS.
//
// The constraint is implicitly universally quantified over any type
// parameters appearing within the two types.
type Constraint struct {
	LHS, RHS types.Type
}

// A Finder inspects the type-checked ASTs of Go packages and
// accumulates the set of type constraints (x, y) such that x is
// assignable to y, y is an interface, and both x and y have methods.
//
// In other words, it returns the subset of the "implements" relation
// that is checked during compilation of a package.  Refactoring tools
// will need to preserve at least this part of the relation to ensure
// continued compilation.
type Finder struct {
	Result    map[Constraint]bool
	msetcache typeutil.MethodSetCache

	// per-Find state
	info *types.Info
	sig  *types.Signature
}

// Find inspects a single package, populating Result with its pairs of
// constrained types.
//
// The result is non-canonical and thus may contain duplicates (but this
// tends to preserves names of interface types better).
//
// The package must be free of type errors, and
// info.{Defs,Uses,Selections,Types} must have been populated by the
// type-checker.
func (f *Finder) Find(info *types.Info, files []*ast.File) {
	if info.Defs == nil || info.Uses == nil || info.Selections == nil || info.Types == nil {
		panic("Finder.Find: one of info.{Defs,Uses,Selections.Types} is not populated")
	}
	if f.Result == nil {
		f.Result = make(map[Constraint]bool)
	}

	f.info = info
	for _, file := range files {
		for _, d := range file.Decls {
			switch d := d.(type) {
			case *ast.GenDecl:
				if d.Tok == token.VAR { // ignore consts
					for _, spec := range d.Specs {
						f.valueSpec(spec.(*ast.ValueSpec))
					}
				}

			case *ast.FuncDecl:
				if d.Body != nil {
					f.sig = f.info.Defs[d.Name].Type().(*types.Signature)
					f.stmt(d.Body)
					f.sig = nil
				}
			}
		}
	}
	f.info = nil
}

var (
	tInvalid     = types.Typ[types.Invalid]
	tUntypedBool = types.Typ[types.UntypedBool]
	tUntypedNil  = types.Typ[types.UntypedNil]
)

// exprN visits an expression in a multi-value context.
func (f *Finder) exprN(e ast.Expr) types.Type {
	typ := f.info.Types[e].Type.(*types.Tuple)
	switch e := e.(type) {
	case *ast.ParenExpr:
		return f.exprN(e.X)

	case *ast.CallExpr:
		// x, err := f(args)
		sig := typeparams.CoreType(f.expr(e.Fun)).(*types.Signature)
		f.call(sig, e.Args)

	case *ast.IndexExpr:
		// y, ok := x[i]
		x := f.expr(e.X)
		f.assign(f.expr(e.Index), typeparams.CoreType(x).(*types.Map).Key())

	case *ast.TypeAssertExpr:
		// y, ok := x.(T)
		f.typeAssert(f.expr(e.X), typ.At(0).Type())

	case *ast.UnaryExpr: // must be receive <-
		// y, ok := <-x
		f.expr(e.X)

	default:
		panic(e)
	}
	return typ
}

func (f *Finder) call(sig *types.Signature, args []ast.Expr) {
	if len(args) == 0 {
		return
	}

	// Ellipsis call?  e.g. f(x, y, z...)
	if _, ok := args[len(args)-1].(*ast.Ellipsis); ok {
		for i, arg := range args {
			// The final arg is a slice, and so is the final param.
			f.assign(sig.Params().At(i).Type(), f.expr(arg))
		}
		return
	}

	var argtypes []types.Type

	// Gather the effective actual parameter types.
	if tuple, ok := f.info.Types[args[0]].Type.(*types.Tuple); ok {
		// f(g()) call where g has multiple results?
		f.expr(args[0])
		// unpack the tuple
		for v := range tuple.Variables() {
			argtypes = append(argtypes, v.Type())
		}
	} else {
		for _, arg := range args {
			argtypes = append(argtypes, f.expr(arg))
		}
	}

	// Assign the actuals to the formals.
	if !sig.Variadic() {
		for i, argtype := range argtypes {
			f.assign(sig.Params().At(i).Type(), argtype)
		}
	} else {
		// The first n-1 parameters are assigned normally.
		nnormals := sig.Params().Len() - 1
		for i, argtype := range argtypes[:nnormals] {
			f.assign(sig.Params().At(i).Type(), argtype)
		}
		// Remaining args are assigned to elements of varargs slice.
		tElem := sig.Params().At(nnormals).Type().(*types.Slice).Elem()
		for i := nnormals; i < len(argtypes); i++ {
			f.assign(tElem, argtypes[i])
		}
	}
}

// builtin visits the arguments of a builtin type with signature sig.
func (f *Finder) builtin(obj *types.Builtin, sig *types.Signature, args []ast.Expr) {
	switch obj.Name() {
	case "make", "new":
		for i, arg := range args {
			if i == 0 && f.info.Types[arg].IsType() {
				continue // skip the type operand
			}
			f.expr(arg)
		}

	case "append":
		s := f.expr(args[0])
		if _, ok := args[len(args)-1].(*ast.Ellipsis); ok && len(args) == 2 {
			// append(x, y...)   including append([]byte, "foo"...)
			f.expr(args[1])
		} else {
			// append(x, y, z)
			tElem := typeparams.CoreType(s).(*types.Slice).Elem()
			for _, arg := range args[1:] {
				f.assign(tElem, f.expr(arg))
			}
		}

	case "delete":
		m := f.expr(args[0])
		k := f.expr(args[1])
		f.assign(typeparams.CoreType(m).(*types.Map).Key(), k)

	default:
		// ordinary call
		f.call(sig, args)
	}
}

func (f *Finder) extract(tuple types.Type, i int) types.Type {
	if tuple, ok := tuple.(*types.Tuple); ok && i < tuple.Len() {
		return tuple.At(i).Type()
	}
	return tInvalid
}

func (f *Finder) valueSpec(spec *ast.ValueSpec) {
	var T types.Type
	if spec.Type != nil {
		T = f.info.Types[spec.Type].Type
	}
	switch len(spec.Values) {
	case len(spec.Names): // e.g. var x, y = f(), g()
		for _, value := range spec.Values {
			v := f.expr(value)
			if T != nil {
				f.assign(T, v)
			}
		}

	case 1: // e.g. var x, y = f()
		tuple := f.exprN(spec.Values[0])
		for i := range spec.Names {
			if T != nil {
				f.assign(T, f.extract(tuple, i))
			}
		}
	}
}

// assign records pairs of distinct types that are related by
// assignability, where the left-hand side is an interface and both
// sides have methods.
//
// It should be called for all assignability checks, type assertions,
// explicit conversions and comparisons between two types, unless the
// types are uninteresting (e.g. lhs is a concrete type, or the empty
// interface; rhs has no methods).
func (f *Finder) assign(lhs, rhs types.Type) {
	if types.Identical(lhs, rhs) {
		return
	}
	if !types.IsInterface(lhs) {
		return
	}

	if f.msetcache.MethodSet(lhs).Len() == 0 {
		return
	}
	if f.msetcache.MethodSet(rhs).Len() == 0 {
		return
	}
	// record the pair
	f.Result[Constraint{lhs, rhs}] = true
}

// typeAssert must be called for each type assertion x.(T) where x has
// interface type I.
func (f *Finder) typeAssert(I, T types.Type) {
	// Type assertions are slightly subtle, because they are allowed
	// to be "impossible", e.g.
	//
	// 	var x interface{f()}
	//	_ = x.(interface{f()int}) // legal
	//
	// (In hindsight, the language spec should probably not have
	// allowed this, but it's too late to fix now.)
	//
	// This means that a type assert from I to T isn't exactly a
	// constraint that T is assignable to I, but for a refactoring
	// tool it is a conditional constraint that, if T is assignable
	// to I before a refactoring, it should remain so after.

	if types.AssignableTo(T, I) {
		f.assign(I, T)
	}
}

// compare must be called for each comparison x==y.
func (f *Finder) compare(x, y types.Type) {
	if types.AssignableTo(x, y) {
		f.assign(y, x)
	} else if types.AssignableTo(y, x) {
		f.assign(x, y)
	}
}

// expr visits a true expression (not a type or defining ident)
// and returns its type.
func (f *Finder) expr(e ast.Expr) types.Type {
	tv := f.info.Types[e]
	if tv.Value != nil {
		return tv.Type // prune the descent for constants
	}

	// tv.Type may be nil for an ast.Ident.

	switch e := e.(type) {
	case *ast.BadExpr, *ast.BasicLit:
		// no-op

	case *ast.Ident:
		// (referring idents only)
		if obj, ok := f.info.Uses[e]; ok {
			return obj.Type()
		}
		if e.Name == "_" { // e.g. "for _ = range x"
			return tInvalid
		}
		panic("undefined ident: " + e.Name)

	case *ast.Ellipsis:
		if e.Elt != nil {
			f.expr(e.Elt)
		}

	case *ast.FuncLit:
		saved := f.sig
		f.sig = tv.Type.(*types.Signature)
		f.stmt(e.Body)
		f.sig = saved

	case *ast.CompositeLit:
		switch T := typeparams.CoreType(typeparams.Deref(tv.Type)).(type) {
		case *types.Struct:
			for i, elem := range e.Elts {
				if kv, ok := elem.(*ast.KeyValueExpr); ok {
					f.assign(f.info.Uses[kv.Key.(*ast.Ident)].Type(), f.expr(kv.Value))
				} else {
					f.assign(T.Field(i).Type(), f.expr(elem))
				}
			}

		case *types.Map:
			for _, elem := range e.Elts {
				elem := elem.(*ast.KeyValueExpr)
				f.assign(T.Key(), f.expr(elem.Key))
				f.assign(T.Elem(), f.expr(elem.Value))
			}

		case *types.Array, *types.Slice:
			tElem := T.(interface {
				Elem() types.Type
			}).Elem()
			for _, elem := range e.Elts {
				if kv, ok := elem.(*ast.KeyValueExpr); ok {
					// ignore the key
					f.assign(tElem, f.expr(kv.Value))
				} else {
					f.assign(tElem, f.expr(elem))
				}
			}

		default:
			panic(fmt.Sprintf("unexpected composite literal type %T: %v", tv.Type, tv.Type.String()))
		}

	case *ast.ParenExpr:
		f.expr(e.X)

	case *ast.SelectorExpr:
		if seln, ok := f.info.Selections[e]; ok {
			// If e.X is a type (e.g., e is interface{ m() }.m), don't visit it.
			if seln.Kind() != types.MethodExpr {
				f.expr(e.X)
			}
		} else {
			return f.info.Uses[e.Sel].Type() // qualified identifier
		}

	case *ast.IndexExpr:
		if instance(f.info, e.X) {
			// f[T] or C[T] -- generic instantiation
		} else {
			// x[i] or m[k] -- index or lookup operation
			x := f.expr(e.X)
			i := f.expr(e.Index)
			if ux, ok := typeparams.CoreType(x).(*types.Map); ok {
				f.assign(ux.Key(), i)
			}
		}

	case *ast.IndexListExpr:
		// f[X, Y] -- generic instantiation

	case *ast.SliceExpr:
		f.expr(e.X)
		if e.Low != nil {
			f.expr(e.Low)
		}
		if e.High != nil {
			f.expr(e.High)
		}
		if e.Max != nil {
			f.expr(e.Max)
		}

	case *ast.TypeAssertExpr:
		x := f.expr(e.X)
		f.typeAssert(x, f.info.Types[e.Type].Type)

	case *ast.CallExpr:
		if tvFun := f.info.Types[e.Fun]; tvFun.IsType() {
			// conversion
			arg0 := f.expr(e.Args[0])
			f.assign(tvFun.Type, arg0)
		} else {
			// function call

			// unsafe call. Treat calls to functions in unsafe like ordinary calls,
			// except that their signature cannot be determined by their func obj.
			// Without this special handling, f.expr(e.Fun) would fail below.
			if s, ok := ast.Unparen(e.Fun).(*ast.SelectorExpr); ok {
				if obj, ok := f.info.Uses[s.Sel].(*types.Builtin); ok && obj.Pkg().Path() == "unsafe" {
					sig := f.info.Types[e.Fun].Type.(*types.Signature)
					f.call(sig, e.Args)
					return tv.Type
				}
			}

			// builtin call
			if id, ok := ast.Unparen(e.Fun).(*ast.Ident); ok {
				if obj, ok := f.info.Uses[id].(*types.Builtin); ok {
					sig := f.info.Types[id].Type.(*types.Signature)
					f.builtin(obj, sig, e.Args)
					return tv.Type
				}
			}

			// ordinary call
			f.call(typeparams.CoreType(f.expr(e.Fun)).(*types.Signature), e.Args)
		}

	case *ast.StarExpr:
		f.expr(e.X)

	case *ast.UnaryExpr:
		f.expr(e.X)

	case *ast.BinaryExpr:
		x := f.expr(e.X)
		y := f.expr(e.Y)
		if e.Op == token.EQL || e.Op == token.NEQ {
			f.compare(x, y)
		}

	case *ast.KeyValueExpr:
		f.expr(e.Key)
		f.expr(e.Value)

	case *ast.ArrayType,
		*ast.StructType,
		*ast.FuncType,
		*ast.InterfaceType,
		*ast.MapType,
		*ast.ChanType:
		panic(e)
	}

	if tv.Type == nil {
		panic(fmt.Sprintf("no type for %T", e))
	}

	return tv.Type
}

func (f *Finder) stmt(s ast.Stmt) {
	switch s := s.(type) {
	case *ast.BadStmt,
		*ast.EmptyStmt,
		*ast.BranchStmt:
		// no-op

	case *ast.DeclStmt:
		d := s.Decl.(*ast.GenDecl)
		if d.Tok == token.VAR { // ignore consts
			for _, spec := range d.Specs {
				f.valueSpec(spec.(*ast.ValueSpec))
			}
		}

	case *ast.LabeledStmt:
		f.stmt(s.Stmt)

	case *ast.ExprStmt:
		f.expr(s.X)

	case *ast.SendStmt:
		ch := f.expr(s.Chan)
		val := f.expr(s.Value)
		f.assign(typeparams.CoreType(ch).(*types.Chan).Elem(), val)

	case *ast.IncDecStmt:
		f.expr(s.X)

	case *ast.AssignStmt:
		switch s.Tok {
		case token.ASSIGN, token.DEFINE:
			// y := x   or   y = x
			var rhsTuple types.Type
			if len(s.Lhs) != len(s.Rhs) {
				rhsTuple = f.exprN(s.Rhs[0])
			}
			for i := range s.Lhs {
				var lhs, rhs types.Type
				if rhsTuple == nil {
					rhs = f.expr(s.Rhs[i]) // 1:1 assignment
				} else {
					rhs = f.extract(rhsTuple, i) // n:1 assignment
				}

				if id, ok := s.Lhs[i].(*ast.Ident); ok {
					if id.Name != "_" {
						if obj, ok := f.info.Defs[id]; ok {
							lhs = obj.Type() // definition
						}
					}
				}
				if lhs == nil {
					lhs = f.expr(s.Lhs[i]) // assignment
				}
				f.assign(lhs, rhs)
			}

		default:
			// y op= x
			f.expr(s.Lhs[0])
			f.expr(s.Rhs[0])
		}

	case *ast.GoStmt:
		f.expr(s.Call)

	case *ast.DeferStmt:
		f.expr(s.Call)

	case *ast.ReturnStmt:
		formals := f.sig.Results()
		switch len(s.Results) {
		case formals.Len(): // 1:1
			for i, result := range s.Results {
				f.assign(formals.At(i).Type(), f.expr(result))
			}

		case 1: // n:1
			tuple := f.exprN(s.Results[0])
			for i := 0; i < formals.Len(); i++ {
				f.assign(formals.At(i).Type(), f.extract(tuple, i))
			}
		}

	case *ast.SelectStmt:
		f.stmt(s.Body)

	case *ast.BlockStmt:
		for _, s := range s.List {
			f.stmt(s)
		}

	case *ast.IfStmt:
		if s.Init != nil {
			f.stmt(s.Init)
		}
		f.expr(s.Cond)
		f.stmt(s.Body)
		if s.Else != nil {
			f.stmt(s.Else)
		}

	case *ast.SwitchStmt:
		if s.Init != nil {
			f.stmt(s.Init)
		}
		var tag types.Type = tUntypedBool
		if s.Tag != nil {
			tag = f.expr(s.Tag)
		}
		for _, cc := range s.Body.List {
			cc := cc.(*ast.CaseClause)
			for _, cond := range cc.List {
				f.compare(tag, f.info.Types[cond].Type)
			}
			for _, s := range cc.Body {
				f.stmt(s)
			}
		}

	case *ast.TypeSwitchStmt:
		if s.Init != nil {
			f.stmt(s.Init)
		}
		var I types.Type
		switch ass := s.Assign.(type) {
		case *ast.ExprStmt: // x.(type)
			I = f.expr(ast.Unparen(ass.X).(*ast.TypeAssertExpr).X)
		case *ast.AssignStmt: // y := x.(type)
			I = f.expr(ast.Unparen(ass.Rhs[0]).(*ast.TypeAssertExpr).X)
		}
		for _, cc := range s.Body.List {
			cc := cc.(*ast.CaseClause)
			for _, cond := range cc.List {
				tCase := f.info.Types[cond].Type
				if tCase != tUntypedNil {
					f.typeAssert(I, tCase)
				}
			}
			for _, s := range cc.Body {
				f.stmt(s)
			}
		}

	case *ast.CommClause:
		if s.Comm != nil {
			f.stmt(s.Comm)
		}
		for _, s := range s.Body {
			f.stmt(s)
		}

	case *ast.ForStmt:
		if s.Init != nil {
			f.stmt(s.Init)
		}
		if s.Cond != nil {
			f.expr(s.Cond)
		}
		if s.Post != nil {
			f.stmt(s.Post)
		}
		f.stmt(s.Body)

	case *ast.RangeStmt:
		x := f.expr(s.X)
		// No conversions are involved when Tok==DEFINE.
		if s.Tok == token.ASSIGN {
			if s.Key != nil {
				k := f.expr(s.Key)
				var xelem types.Type
				// Keys of array, *array, slice, string aren't interesting
				// since the RHS key type is just an int.
				switch ux := typeparams.CoreType(x).(type) {
				case *types.Chan:
					xelem = ux.Elem()
				case *types.Map:
					xelem = ux.Key()
				}
				if xelem != nil {
					f.assign(k, xelem)
				}
			}
			if s.Value != nil {
				val := f.expr(s.Value)
				var xelem types.Type
				// Values of type strings aren't interesting because
				// the RHS value type is just a rune.
				switch ux := typeparams.CoreType(x).(type) {
				case *types.Array:
					xelem = ux.Elem()
				case *types.Map:
					xelem = ux.Elem()
				case *types.Pointer: // *array
					xelem = typeparams.CoreType(typeparams.Deref(ux)).(*types.Array).Elem()
				case *types.Slice:
					xelem = ux.Elem()
				}
				if xelem != nil {
					f.assign(val, xelem)
				}
			}
		}
		f.stmt(s.Body)

	default:
		panic(s)
	}
}

// -- Plundered from golang.org/x/tools/go/ssa -----------------

func instance(info *types.Info, expr ast.Expr) bool {
	var id *ast.Ident
	switch x := expr.(type) {
	case *ast.Ident:
		id = x
	case *ast.SelectorExpr:
		id = x.Sel
	default:
		return false
	}
	_, ok := info.Instances[id]
	return ok
}


================================================
FILE: refactor/satisfy/find_test.go
================================================
// Copyright 2022 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package satisfy_test

import (
	"fmt"
	"go/ast"
	"go/importer"
	"go/parser"
	"go/token"
	"go/types"
	"reflect"
	"sort"
	"testing"

	"golang.org/x/tools/internal/testenv"
	"golang.org/x/tools/refactor/satisfy"
)

// This test exercises various operations on core types of type parameters.
// (It also provides pretty decent coverage of the non-generic operations.)
func TestGenericCoreOperations(t *testing.T) {
	const src = `package foo

import "unsafe"

type I interface { f() }

type impl struct{}
func (impl) f() {}

// A big pile of single-serving types that implement I.
type A struct{impl}
type B struct{impl}
type C struct{impl}
type D struct{impl}
type E struct{impl}
type F struct{impl}
type G struct{impl}
type H struct{impl}
type J struct{impl}
type K struct{impl}
type L struct{impl}
type M struct{impl}
type N struct{impl}
type O struct{impl}
type P struct{impl}
type Q struct{impl}
type R struct{impl}
type S struct{impl}
type T struct{impl}
type U struct{impl}
type V struct{impl}
type W struct{impl}
type X struct{impl}

type Generic[T any] struct{impl}
func (Generic[T]) g(T) {}

type GI[T any] interface{
	g(T)
}

func _[Slice interface{ []I }](s Slice) Slice {
	s[0] = L{} // I <- L
	return append(s, A{}) // I <- A
}

func _[Func interface{ func(I) B }](fn Func) {
	b := fn(C{}) // I <- C
	var _ I = b // I <- B
}

func _[Chan interface{ chan D }](ch Chan) {
	var i I
	for i = range ch {} // I <- D
	_ = i
}

func _[Chan interface{ chan E }](ch Chan) {
	var _ I = <-ch // I <- E
}

func _[Chan interface{ chan I }](ch Chan) {
	ch <- F{} // I <- F
}

func _[Map interface{ map[G]H }](m Map) {
	var k, v I
	for k, v = range m {} // I <- G, I <- H
	_, _ = k, v
}

func _[Map interface{ map[I]K }](m Map) {
	var _ I = m[J{}] // I <- J, I <- K
	delete(m, R{}) // I <- R
	_, _ = m[J{}]
}

func _[Array interface{ [1]I }](a Array) {
	a[0] = M{} // I <- M
}

func _[Array interface{ [1]N }](a Array) {
	var _ I = a[0] // I <- N
}

func _[Array interface{ [1]O }](a Array) {
	var v I
	for _, v = range a {} // I <- O
	_ = v
}

func _[ArrayPtr interface{ *[1]P }](a ArrayPtr) {
	var v I
	for _, v = range a {} // I <- P
	_ = v
}

func _[Slice interface{ []Q }](s Slice) {
	var v I
	for _, v = range s {} // I <- Q
	_ = v
}

func _[Func interface{ func() (S, bool) }](fn Func) {
	var i I
	i, _ = fn() // I <- S
	_ = i
}

func _() I {
	var _ I = T{} // I <- T
	var _ I = Generic[T]{} // I <- Generic[T]
	var _ I = Generic[string]{} // I <- Generic[string]
	return U{} // I <- U
}

var _ GI[string] = Generic[string]{} //  GI[string] <- Generic[string]

// universally quantified constraints:
// the type parameter may appear on the left, the right, or both sides.

func  _[T any](g Generic[T]) GI[T] {
	return g // GI[T] <- Generic[T]
}

func  _[T any]() {
	type GI2[T any] interface{ g(string) }
	var _ GI2[T] = Generic[string]{} // GI2[T] <- Generic[string]
}

type Gen2[T any] struct{}
func (f Gen2[T]) g(string) { global = f } // GI[string] <- Gen2[T]

var global GI[string]

func _() {
	var x [3]V
	// golang/go#56227: the finder should visit calls in the unsafe package.
	_ = unsafe.Slice(&x[0], func() int { var _ I = x[0]; return 3 }()) // I <- V
}

func _[P ~struct{F I}]() {
	_ = P{W{}}
	_ = P{F: X{}}
}

// golang/go#77625: don't panic on a method expression of an anonymous interface.
var _ = interface{ m() }.m
`
	got := constraints(t, src)
	want := []string{
		"p.GI2[T] <- p.Generic[string]", // implicitly "forall T" quantified
		"p.GI[T] <- p.Generic[T]",       // implicitly "forall T" quantified
		"p.GI[string] <- p.Gen2[T]",     // implicitly "forall T" quantified
		"p.GI[string] <- p.Generic[string]",
		"p.I <- p.A",
		"p.I <- p.B",
		"p.I <- p.C",
		"p.I <- p.D",
		"p.I <- p.E",
		"p.I <- p.F",
		"p.I <- p.G",
		"p.I <- p.Generic[p.T]",
		"p.I <- p.Generic[string]",
		"p.I <- p.H",
		"p.I <- p.J",
		"p.I <- p.K",
		"p.I <- p.L",
		"p.I <- p.M",
		"p.I <- p.N",
		"p.I <- p.O",
		"p.I <- p.P",
		"p.I <- p.Q",
		"p.I <- p.R",
		"p.I <- p.S",
		"p.I <- p.T",
		"p.I <- p.U",
		"p.I <- p.V",
		"p.I <- p.W",
		"p.I <- p.X",
	}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("found unexpected constraints: got %s, want %s", got, want)
	}
}

func TestNewExpr(t *testing.T) {
	testenv.NeedsGo1Point(t, 26)
	const src = `package p

type I interface{ f() }
type C int
func (C) f() {}

var _ I = new(C(123))
`
	got := constraints(t, src)
	want := []string{
		"p.I <- *p.C",
	}
	if !reflect.DeepEqual(got, want) {
		t.Fatalf("found unexpected constraints: got %s, want %s", got, want)
	}
}

func constraints(t *testing.T, src string) []string {
	// parse
	fset := token.NewFileSet()
	f, err := parser.ParseFile(fset, "p.go", src, 0)
	if err != nil {
		t.Fatal(err) // parse error
	}
	files := []*ast.File{f}

	// type-check
	info := &types.Info{
		Types:        make(map[ast.Expr]types.TypeAndValue),
		Defs:         make(map[*ast.Ident]types.Object),
		Uses:         make(map[*ast.Ident]types.Object),
		Implicits:    make(map[ast.Node]types.Object),
		Instances:    make(map[*ast.Ident]types.Instance),
		Scopes:       make(map[ast.Node]*types.Scope),
		Selections:   make(map[*ast.SelectorExpr]*types.Selection),
		FileVersions: make(map[*ast.File]string),
	}
	conf := types.Config{
		Importer: importer.Default(),
	}
	if _, err := conf.Check("p", fset, files, info); err != nil {
		t.Fatal(err) // type error
	}

	// gather constraints
	var finder satisfy.Finder
	finder.Find(info, files)
	var constraints []string
	for c := range finder.Result {
		constraints = append(constraints, fmt.Sprintf("%v <- %v", c.LHS, c.RHS))
	}
	sort.Strings(constraints)
	return constraints
}


================================================
FILE: txtar/archive.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// Package txtar implements a trivial text-based file archive format.
//
// The goals for the format are:
//
//   - be trivial enough to create and edit by hand.
//   - be able to store trees of text files describing go command test cases.
//   - diff nicely in git history and code reviews.
//
// Non-goals include being a completely general archive format,
// storing binary data, storing file modes, storing special files like
// symbolic links, and so on.
//
// # Txtar format
//
// A txtar archive is zero or more comment lines and then a sequence of file entries.
// Each file entry begins with a file marker line of the form "-- FILENAME --"
// and is followed by zero or more file content lines making up the file data.
// The comment or file content ends at the next file marker line.
// The file marker line must begin with the three-byte sequence "-- "
// and end with the three-byte sequence " --", but the enclosed
// file name can be surrounding by additional white space,
// all of which is stripped.
//
// If the txtar file is missing a trailing newline on the final line,
// parsers should consider a final newline to be present anyway.
//
// There are no possible syntax errors in a txtar archive.
package txtar

import (
	"bytes"
	"fmt"
	"os"
	"strings"
)

// An Archive is a collection of files.
type Archive struct {
	Comment []byte
	Files   []File
}

// A File is a single file in an archive.
type File struct {
	Name string // name of file ("foo/bar.txt")
	Data []byte // text content of file
}

// Format returns the serialized form of an Archive.
// It is assumed that the Archive data structure is well-formed:
// a.Comment and all a.File[i].Data contain no file marker lines,
// and all a.File[i].Name is non-empty.
func Format(a *Archive) []byte {
	var buf bytes.Buffer
	buf.Write(fixNL(a.Comment))
	for _, f := range a.Files {
		fmt.Fprintf(&buf, "-- %s --\n", f.Name)
		buf.Write(fixNL(f.Data))
	}
	return buf.Bytes()
}

// ParseFile parses the named file as an archive.
func ParseFile(file string) (*Archive, error) {
	data, err := os.ReadFile(file)
	if err != nil {
		return nil, err
	}
	return Parse(data), nil
}

// Parse parses the serialized form of an Archive.
// The returned Archive holds slices of data.
func Parse(data []byte) *Archive {
	a := new(Archive)
	var name string
	a.Comment, name, data = findFileMarker(data)
	for name != "" {
		f := File{name, nil}
		f.Data, name, data = findFileMarker(data)
		a.Files = append(a.Files, f)
	}
	return a
}

var (
	newlineMarker = []byte("\n-- ")
	marker        = []byte("-- ")
	markerEnd     = []byte(" --")
)

// findFileMarker finds the next file marker in data,
// extracts the file name, and returns the data before the marker,
// the file name, and the data after the marker.
// If there is no next marker, findFileMarker returns before = fixNL(data), name = "", after = nil.
func findFileMarker(data []byte) (before []byte, name string, after []byte) {
	var i int
	for {
		if name, after = isMarker(data[i:]); name != "" {
			return data[:i], name, after
		}
		j := bytes.Index(data[i:], newlineMarker)
		if j < 0 {
			return fixNL(data), "", nil
		}
		i += j + 1 // positioned at start of new possible marker
	}
}

// isMarker checks whether data begins with a file marker line.
// If so, it returns the name from the line and the data after the line.
// Otherwise it returns name == "" with an unspecified after.
func isMarker(data []byte) (name string, after []byte) {
	if !bytes.HasPrefix(data, marker) {
		return "", nil
	}
	if i := bytes.IndexByte(data, '\n'); i >= 0 {
		data, after = data[:i], data[i+1:]
		if data[i-1] == '\r' { // handle \r\n line ending
			data = data[:i-1]
		}
	}
	if !(bytes.HasSuffix(data, markerEnd) && len(data) >= len(marker)+len(markerEnd)) {
		return "", nil
	}
	return strings.TrimSpace(string(data[len(marker) : len(data)-len(markerEnd)])), after
}

// If data is empty or ends in \n, fixNL returns data.
// Otherwise fixNL returns a new slice consisting of data with a final \n added.
func fixNL(data []byte) []byte {
	if len(data) == 0 || data[len(data)-1] == '\n' {
		return data
	}
	d := make([]byte, len(data)+1)
	copy(d, data)
	d[len(data)] = '\n'
	return d
}


================================================
FILE: txtar/archive_test.go
================================================
// Copyright 2018 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package txtar

import (
	"bytes"
	"fmt"
	"reflect"
	"testing"
)

func TestParse(t *testing.T) {
	var tests = []struct {
		name   string
		text   string
		parsed *Archive
	}{
		{
			name: "basic",
			text: `comment1
comment2
-- file1 --
File 1 text.
-- foo ---
More file 1 text.
-- file 2 --
File 2 text.
-- empty --
-- noNL --
hello world
-- empty filename line --
some content
-- --`,
			parsed: &Archive{
				Comment: []byte("comment1\ncomment2\n"),
				Files: []File{
					{"file1", []byte("File 1 text.\n-- foo ---\nMore file 1 text.\n")},
					{"file 2", []byte("File 2 text.\n")},
					{"empty", []byte{}},
					{"noNL", []byte("hello world\n")},
					{"empty filename line", []byte("some content\n-- --\n")},
				},
			},
		},
		{
			name: "crlf",
			text: "comment\r\n-- file --\r\ndata\r\n",
			parsed: &Archive{
				Comment: []byte("comment\r\n"),
				Files:   []File{{"file", []byte("data\r\n")}},
			},
		},
		{
			name: "utf8 and comment",
			text: `# This is a test comment
-- hello.txt --
Hello
-- unicode.txt --
Go语言
`,
			parsed: &Archive{
				Comment: []byte("# This is a test comment\n"),
				Files: []File{
					{"hello.txt", []byte("Hello\n")},
					{"unicode.txt", []byte("Go语言\n")},
				},
			},
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			a := Parse([]byte(tt.text))
			if !reflect.DeepEqual(a, tt.parsed) {
				t.Fatalf("Parse: wrong output:\nhave:\n%s\nwant:\n%s", shortArchive(a), shortArchive(tt.parsed))
			}
			text := Format(a)
			a = Parse(text)
			if !reflect.DeepEqual(a, tt.parsed) {
				t.Fatalf("Parse after Format: wrong output:\nhave:\n%s\nwant:\n%s", shortArchive(a), shortArchive(tt.parsed))
			}
		})
	}
}

func TestFormat(t *testing.T) {
	var tests = []struct {
		name   string
		input  *Archive
		wanted string
	}{
		{
			name: "basic",
			input: &Archive{
				Comment: []byte("comment1\ncomment2\n"),
				Files: []File{
					{"file1", []byte("File 1 text.\n-- foo ---\nMore file 1 text.\n")},
					{"file 2", []byte("File 2 text.\n")},
					{"empty", []byte{}},
					{"noNL", []byte("hello world")},
				},
			},
			wanted: `comment1
comment2
-- file1 --
File 1 text.
-- foo ---
More file 1 text.
-- file 2 --
File 2 text.
-- empty --
-- noNL --
hello world
`,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := Format(tt.input)
			if string(result) != tt.wanted {
				t.Errorf("Wrong output. \nGot:\n%s\nWant:\n%s\n", string(result), tt.wanted)
			}
		})
	}
}

func shortArchive(a *Archive) string {
	var buf bytes.Buffer
	fmt.Fprintf(&buf, "comment: %q\n", a.Comment)
	for _, f := range a.Files {
		fmt.Fprintf(&buf, "file %q: %q\n", f.Name, f.Data)
	}
	return buf.String()
}


================================================
FILE: txtar/fs.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package txtar

import (
	"errors"
	"fmt"
	"io"
	"io/fs"
	"path"
	"slices"
	"time"
)

// FS returns the file system form of an Archive.
// It returns an error if any of the file names in the archive
// are not valid file system names.
// The archive must not be modified while the FS is in use.
//
// If the file system detects that it has been modified, calls to the
// file system return an ErrModified error.
func FS(a *Archive) (fs.FS, error) {
	// Create a filesystem with a root directory.
	root := &node{fileinfo: fileinfo{path: ".", mode: readOnlyDir}}
	fsys := &filesystem{a, map[string]*node{root.path: root}}

	if err := initFiles(fsys); err != nil {
		return nil, fmt.Errorf("cannot create fs.FS from txtar.Archive: %s", err)
	}
	return fsys, nil
}

const (
	readOnly    fs.FileMode = 0o444 // read only mode
	readOnlyDir             = readOnly | fs.ModeDir
)

// ErrModified indicates that file system returned by FS
// noticed that the underlying archive has been modified
// since the call to FS. Detection of modification is best effort,
// to help diagnose misuse of the API, and is not guaranteed.
var ErrModified error = errors.New("txtar.Archive has been modified during txtar.FS")

// A filesystem is a simple in-memory file system for txtar archives,
// represented as a map from valid path names to information about the
// files or directories they represent.
//
// File system operations are read only. Modifications to the underlying
// *Archive may race. To help prevent this, the filesystem tries
// to detect modification during Open and return ErrModified if it
// is able to detect a modification.
type filesystem struct {
	ar    *Archive
	nodes map[string]*node
}

// node is a file or directory in the tree of a filesystem.
type node struct {
	fileinfo               // fs.FileInfo and fs.DirEntry implementation
	idx      int           // index into ar.Files (for files)
	entries  []fs.DirEntry // subdirectories and files (for directories)
}

var _ fs.FS = (*filesystem)(nil)
var _ fs.DirEntry = (*node)(nil)

// initFiles initializes fsys from fsys.ar.Files. Returns an error if there are any
// invalid file names or collisions between file or directories.
func initFiles(fsys *filesystem) error {
	for idx, file := range fsys.ar.Files {
		name := file.Name
		if !fs.ValidPath(name) {
			return fmt.Errorf("file %q is an invalid path", name)
		}

		n := &node{idx: idx, fileinfo: fileinfo{path: name, size: len(file.Data), mode: readOnly}}
		if err := insert(fsys, n); err != nil {
			return err
		}
	}
	return nil
}

// insert adds node n as an entry to its parent directory within the filesystem.
func insert(fsys *filesystem, n *node) error {
	if m := fsys.nodes[n.path]; m != nil {
		return fmt.Errorf("duplicate path %q", n.path)
	}
	fsys.nodes[n.path] = n

	// fsys.nodes contains "." to prevent infinite loops.
	parent, err := directory(fsys, path.Dir(n.path))
	if err != nil {
		return err
	}
	parent.entries = append(parent.entries, n)
	return nil
}

// directory returns the directory node with the path dir and lazily-creates it
// if it does not exist.
func directory(fsys *filesystem, dir string) (*node, error) {
	if m := fsys.nodes[dir]; m != nil && m.IsDir() {
		return m, nil // pre-existing directory
	}

	n := &node{fileinfo: fileinfo{path: dir, mode: readOnlyDir}}
	if err := insert(fsys, n); err != nil {
		return nil, err
	}
	return n, nil
}

// dataOf returns the data associated with the file t.
// May return ErrModified if fsys.ar has been modified.
func dataOf(fsys *filesystem, n *node) ([]byte, error) {
	if n.idx >= len(fsys.ar.Files) {
		return nil, ErrModified
	}

	f := fsys.ar.Files[n.idx]
	if f.Name != n.path || len(f.Data) != n.size {
		return nil, ErrModified
	}
	return f.Data, nil
}

func (fsys *filesystem) Open(name string) (fs.File, error) {
	if !fs.ValidPath(name) {
		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrInvalid}
	}

	n := fsys.nodes[name]
	switch {
	case n == nil:
		return nil, &fs.PathError{Op: "open", Path: name, Err: fs.ErrNotExist}
	case n.IsDir():
		return &openDir{fileinfo: n.fileinfo, entries: n.entries}, nil
	default:
		data, err := dataOf(fsys, n)
		if err != nil {
			return nil, err
		}
		return &openFile{fileinfo: n.fileinfo, data: data}, nil
	}
}

func (fsys *filesystem) ReadFile(name string) ([]byte, error) {
	file, err := fsys.Open(name)
	if err != nil {
		return nil, err
	}
	if file, ok := file.(*openFile); ok {
		return slices.Clone(file.data), nil
	}
	return nil, &fs.PathError{Op: "read", Path: name, Err: fs.ErrInvalid}
}

// A fileinfo implements fs.FileInfo and fs.DirEntry for a given archive file.
type fileinfo struct {
	path string // unique path to the file or directory within a filesystem
	size int
	mode fs.FileMode
}

var _ fs.FileInfo = (*fileinfo)(nil)
var _ fs.DirEntry = (*fileinfo)(nil)

func (i *fileinfo) Name() string               { return path.Base(i.path) }
func (i *fileinfo) Size() int64                { return int64(i.size) }
func (i *fileinfo) Mode() fs.FileMode          { return i.mode }
func (i *fileinfo) Type() fs.FileMode          { return i.mode.Type() }
func (i *fileinfo) ModTime() time.Time         { return time.Time{} }
func (i *fileinfo) IsDir() bool                { return i.mode&fs.ModeDir != 0 }
func (i *fileinfo) Sys() any                   { return nil }
func (i *fileinfo) Info() (fs.FileInfo, error) { return i, nil }

// An openFile is a regular (non-directory) fs.File open for reading.
type openFile struct {
	fileinfo
	data   []byte
	offset int64
}

var _ fs.File = (*openFile)(nil)

func (f *openFile) Stat() (fs.FileInfo, error) { return &f.fileinfo, nil }
func (f *openFile) Close() error               { return nil }
func (f *openFile) Read(b []byte) (int, error) {
	if f.offset >= int64(len(f.data)) {
		return 0, io.EOF
	}
	if f.offset < 0 {
		return 0, &fs.PathError{Op: "read", Path: f.path, Err: fs.ErrInvalid}
	}
	n := copy(b, f.data[f.offset:])
	f.offset += int64(n)
	return n, nil
}

func (f *openFile) Seek(offset int64, whence int) (int64, error) {
	switch whence {
	case 0:
		// offset += 0
	case 1:
		offset += f.offset
	case 2:
		offset += int64(len(f.data))
	}
	if offset < 0 || offset > int64(len(f.data)) {
		return 0, &fs.PathError{Op: "seek", Path: f.path, Err: fs.ErrInvalid}
	}
	f.offset = offset
	return offset, nil
}

func (f *openFile) ReadAt(b []byte, offset int64) (int, error) {
	if offset < 0 || offset > int64(len(f.data)) {
		return 0, &fs.PathError{Op: "read", Path: f.path, Err: fs.ErrInvalid}
	}
	n := copy(b, f.data[offset:])
	if n < len(b) {
		return n, io.EOF
	}
	return n, nil
}

// A openDir is a directory fs.File (so also an fs.ReadDirFile) open for reading.
type openDir struct {
	fileinfo
	entries []fs.DirEntry
	offset  int
}

var _ fs.ReadDirFile = (*openDir)(nil)

func (d *openDir) Stat() (fs.FileInfo, error) { return &d.fileinfo, nil }
func (d *openDir) Close() error               { return nil }
func (d *openDir) Read(b []byte) (int, error) {
	return 0, &fs.PathError{Op: "read", Path: d.path, Err: fs.ErrInvalid}
}

func (d *openDir) ReadDir(count int) ([]fs.DirEntry, error) {
	n := len(d.entries) - d.offset
	if n == 0 && count > 0 {
		return nil, io.EOF
	}
	if count > 0 && n > count {
		n = count
	}
	list := make([]fs.DirEntry, n)
	copy(list, d.entries[d.offset:d.offset+n])
	d.offset += n
	return list, nil
}


================================================
FILE: txtar/fs_test.go
================================================
// Copyright 2024 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package txtar_test

import (
	"io/fs"
	"strings"
	"testing"
	"testing/fstest"

	"golang.org/x/tools/txtar"
)

func TestFS(t *testing.T) {
	var fstestcases = []struct {
		name, input, files string
	}{
		{
			name:  "empty",
			input: ``,
			files: "",
		},
		{
			name: "one",
			input: `
-- one.txt --
one
`,
			files: "one.txt",
		},
		{
			name: "two",
			input: `
-- one.txt --
one
-- two.txt --
two
`,
			files: "one.txt two.txt",
		},
		{
			name: "subdirectories",
			input: `
-- one.txt --
one
-- 2/two.txt --
two
-- 2/3/three.txt --
three
-- 4/four.txt --
four
`,
			files: "one.txt 2/two.txt 2/3/three.txt 4/four.txt",
		},
	}

	for _, tc := range fstestcases {
		t.Run(tc.name, func(t *testing.T) {
			a := txtar.Parse([]byte(tc.input))
			fsys, err := txtar.FS(a)
			if err != nil {
				t.Fatal(err)
			}

			files := strings.Fields(tc.files)
			if err := fstest.TestFS(fsys, files...); err != nil {
				t.Fatal(err)
			}

			for _, f := range a.Files {
				b, err := fs.ReadFile(fsys, f.Name)
				if err != nil {
					t.Errorf("ReadFile(%q) failed with error: %v", f.Name, err)
				}
				if got, want := string(b), string(f.Data); got != want {
					t.Errorf("ReadFile(%q) = %q; want %q", f.Name, got, want)
				}
			}
		})
	}
}

func TestInvalid(t *testing.T) {
	invalidtestcases := []struct {
		name, want string
		input      string
	}{
		{"unclean file names", "invalid path", `
-- 1/../one.txt --
one
-- 2/sub/../two.txt --
two
`},
		{"duplicate name", `cannot create fs.FS from txtar.Archive: duplicate path "1/2/one.txt"`, `
-- 1/2/one.txt --
one
-- 1/2/one.txt --
two
`},
		{"file conflicts with directory", `duplicate path "1/2"`, `
-- 1/2 --
one
-- 1/2/one.txt --
two
`},
	}

	for _, tc := range invalidtestcases {
		t.Run(tc.name, func(t *testing.T) {
			a := txtar.Parse([]byte(tc.input))
			_, err := txtar.FS(a)
			if err == nil {
				t.Fatal("txtar.FS(...) succeeded; expected an error")
			}
			if got := err.Error(); !strings.Contains(got, tc.want) || tc.want == "" {
				t.Errorf("txtar.FS(...) got error %q; want %q", got, tc.want)
			}
		})
	}
}

func TestModified(t *testing.T) {
	const input = `
-- one.txt --
one
`
	for _, mod := range []func(a *txtar.Archive){
		func(a *txtar.Archive) { a.Files[0].Data = []byte("other") },
		func(a *txtar.Archive) { a.Files[0].Name = "other" },
		func(a *txtar.Archive) { a.Files = nil },
	} {
		a := txtar.Parse([]byte(input))
		if n := len(a.Files); n != 1 {
			t.Fatalf("txtar.Parse(%q) got %d files; expected 1", input, n)
		}

		fsys, err := txtar.FS(a)
		if err != nil {
			t.Fatal(err)
		}

		// Confirm we can open "one.txt".
		_, err = fsys.Open("one.txt")
		if err != nil {
			t.Fatal(err)
		}
		// Modify a to get ErrModified when opening "one.txt".
		mod(a)

		_, err = fsys.Open("one.txt")
		if err != txtar.ErrModified {
			t.Errorf("Open(%q) got error %s; want ErrModified", "one.txt", err)
		}
	}
}

func TestReadFile(t *testing.T) {
	const input = `
-- 1/one.txt --
one
`
	a := txtar.Parse([]byte(input))
	fsys, err := txtar.FS(a)
	if err != nil {
		t.Fatal(err)
	}
	readfs := fsys.(fs.ReadFileFS)
	_, err = readfs.ReadFile("1")
	if err == nil {
		t.Errorf("ReadFile(%q) succeeded; expected an error when reading a directory", "1")
	}

	content, err := readfs.ReadFile("1/one.txt")
	if err != nil {
		t.Fatal(err)
	}
	want := "one\n"
	if got := string(content); want != got {
		t.Errorf("ReadFile(%q) = %q; want %q", "1/one.txt", got, want)
	}
}